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Note: This page contains sample records for the topic "brakes front disk" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


1

Integrated vehicle dynamics control via coordination of active front steering and rear braking  

E-Print Network (OSTI)

front steering and rear braking in a driver- assist system for vehicle yaw control. The proposed control system aims at stabilizing the vehicle while achieving a desired yaw rate. During normal driving braking could be used for yaw rate control. An active suspension system, by controlling the wheel load

Paris-Sud XI, Université de

2

DOES MAGNETIC-FIELD-ROTATION MISALIGNMENT SOLVE THE MAGNETIC BRAKING CATASTROPHE IN PROTOSTELLAR DISK FORMATION?  

SciTech Connect

Stars form in dense cores of molecular clouds that are observed to be significantly magnetized. In the simplest case of a laminar (non-turbulent) core with the magnetic field aligned with the rotation axis, both analytic considerations and numerical simulations have shown that the formation of a large, 10{sup 2} AU scale, rotationally supported protostellar disk is suppressed by magnetic braking in the ideal MHD limit for a realistic level of core magnetization. This theoretical difficulty in forming protostellar disks is termed the ''magnetic braking catastrophe''. A possible resolution to this problem, proposed by Hennebelle and Ciardi and Joos et al., is that misalignment between the magnetic field and rotation axis may weaken the magnetic braking enough to enable disk formation. We evaluate this possibility quantitatively through numerical simulations. We confirm the basic result of Joos et al. that the misalignment is indeed conducive to disk formation. In relatively weakly magnetized cores with dimensionless mass-to-flux ratio {approx}> 4, it enabled the formation of rotationally supported disks that would otherwise be suppressed if the magnetic field and rotation axis are aligned. For more strongly magnetized cores, disk formation remains suppressed, however, even for the maximum tilt angle of 90 Degree-Sign . If dense cores are as strongly magnetized as indicated by OH Zeeman observations (with a mean dimensionless mass-to-flux ratio {approx}2), it would be difficult for the misalignment alone to enable disk formation in the majority of them. We conclude that, while beneficial to disk formation, especially for the relatively weak field case, misalignment does not completely solve the problem of catastrophic magnetic braking in general.

Li Zhiyun [Astronomy Department, University of Virginia, Charlottesville, VA (United States); Krasnopolsky, Ruben; Shang, Hsien [Academia Sinica, Theoretical Institute for Advanced Research in Astrophysics, Taipei, Taiwan (China)

2013-09-01T23:59:59.000Z

3

Hybrid: Braking  

Alternative Fuels and Advanced Vehicles Data Center (EERE)

1 1 Regenerative braking converts otherwise wasted energy from braking into electricity and stores it in the battery. In regenerative braking, the electric motor is reversed so that, instead of using electricity to turn the wheels, the rotating wheels turn the motor and create electricity. Using energy from the wheels to turn the motor slows the vehicle down. Go to next… stage graphic: vertical blue rule Main stage: See through car with battery, engine, and electric motor visible. The car is decelerating. There are arrows flowing from the front wheels to the electric motor to the battery. Main stage: See through car with battery, engine, and electric motor visible. The car is decelerating. There are arrows flowing from the front wheels to the electric motor to the battery.

4

Full Hybrid: Braking  

Alternative Fuels and Advanced Vehicles Data Center (EERE)

Braking button highlighted Stopped button Braking button highlighted Stopped button BRAKING PART 1 Regenerative braking converts otherwise wasted energy from braking into electricity and stores it in the battery. In regenerative braking, the electric motor is reversed so that, instead of using electricity to turn the wheels, the rotating wheels turn the motor and create electricity. Using energy from the wheels to turn the motor slows the vehicle down. Go to next… stage graphic: vertical blue rule Main stage: See through car with battery, engine, generator, power split device, and electric motor visible. The car is decelerating. There are arrows flowing from the front wheels to the power split device to the electric motor to the battery. Main stage: See through car with battery, engine, generator, power split device, and electric motor visible. The car is decelerating. There are arrows flowing from the front wheels to the power split device to the electric motor to the battery.

5

Why Brake-By-Wire (BBW) ? Advantages of BBW  

E-Print Network (OSTI)

Conventional Brake System http://www.conti-online.com #12;BBW Survey [ SKF (Motor + PGT +Ball Screw)] [ DELPHI (Motor + PGT +Ball Screw)] [Continental Teves (Motor + PGT + Roller Screw)] [Continental Teves installed at wheel] #12;Sectional Drawing of the Electromechanically Actuated Disk Brake From ITT Brake Pads Caliper

Yao, Bin

6

Hybrid: Braking  

Alternative Fuels and Advanced Vehicles Data Center (EERE)

2 2 If additional stopping power is needed, conventional friction brakes (e.g., disc brakes) are also applied automatically. Go back… stage graphic: vertical blue rule Main stage: See through car with battery, engine, and electric motor visible. The car is stopped at an intersection. Main stage: See through car with battery, engine, and electric motor visible. The car is stopped at an intersection. Battery: The battery stores energy generated from the gasoline engine or, during regenerative braking, from the electric motor. Since the battery helps power the vehicle, it is larger and holds much more energy than batteries used to start conventional vehicles. Main stage: See through car with battery, engine, and electric motor visible. The car is stopped at an intersection.

7

CURVED WALLS: GRAIN GROWTH, SETTLING, AND COMPOSITION PATTERNS IN T TAURI DISK DUST SUBLIMATION FRONTS  

SciTech Connect

The dust sublimation walls of disks around T Tauri stars represent a directly observable cross-section through the disk atmosphere and midplane. Their emission properties can probe the grain size distribution and composition of the innermost regions of the disk, where terrestrial planets form. Here we calculate the inner dust sublimation wall properties for four classical T Tauri stars with a narrow range of spectral types and inclination angles and a wide range of mass accretion rates to determine the extent to which the walls are radially curved. Best fits to the near- and mid-IR excesses are found for curved, two-layer walls in which the lower layer contains larger, hotter, amorphous pyroxene grains with Mg/(Mg+Fe) = 0.6 and the upper layer contains submicron, cooler, mixed amorphous olivine and forsterite grains. As the mass accretion rates decrease from 10{sup 8} to 10{sup 10} M{sub ?} yr{sup 1}, the maximum grain size in the lower layer decreases from ?3 to 0.5 ?m. We attribute this to a decrease in fragmentation and turbulent support for micron-sized grains with decreasing viscous heating. The atmosphere of these disks is depleted of dust with dust-gas mass ratios 1 10{sup 4} of the interstellar medium (ISM) value, while the midplane is enhanced to eight times the ISM value. For all accretion rates, the wall contributes at least half of the flux in the optically thin 10 ?m silicate feature. Finally, we find evidence for an iron gradient in the disk, suggestive of that found in our solar system.

McClure, M. K.; Calvet, N.; Hartmann, L.; Ingleby, L. [Department of Astronomy, The University of Michigan, 500 Church Street, 830 Dennison Building., Ann Arbor, MI 48109 (United States); D'Alessio, P. [Centro de Radioastronoma y Astrofsica, Universidad Nacional Autnoma de Mxico, 58089 Morelia, Michoacn (Mexico); Espaillat, C. [Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Sargent, B. [Center for Imaging Science and Laboratory for Multiwavelength Astrophysics, Rochester Institute of Technology, 54 Lomb Memorial Drive, Rochester, NY 14623 (United States); Watson, D. M. [Department of Physics and Astronomy, University of Rochester, Rochester, NY 14627 (United States); Hernndez, J., E-mail: melisma@umich.edu, E-mail: ncalvet@umich.edu, E-mail: lhartm@umich.edu, E-mail: lingleby@umich.edu, E-mail: p.dalessio@astrosmo.unam.mx, E-mail: cespaillat@cfa.harvard.edu, E-mail: baspci@rit.edu, E-mail: dmw@pas.rochester.edu, E-mail: hernandj@cida.ve [Centro de Investigaciones de Astronoma (CIDA), Mrida 5101-A (Venezuela, Bolivarian Republic of)

2013-10-01T23:59:59.000Z

8

Hybrid: Braking  

NLE Websites -- All DOE Office Websites (Extended Search)

Button Stopped button highlighted subbanner graphic: gray bar Button Stopped button highlighted subbanner graphic: gray bar STOPPED When the vehicle is stopped, such as at a red light, the gasoline engine and electric motor shut off automatically so that energy is not wasted in idling. The battery continues to power auxillary systems, such as the air conditioning and dashboard displays. stage graphic: vertical blue rule Main stage: See through car with battery, engine, and electric motor visible. The car is stopped at an intersection. Main stage: See through car with battery, engine, and electric motor visible. The car is stopped at an intersection. Battery: The battery stores energy generated from the gasoline engine or, during regenerative braking, from the electric motor. Since the battery helps power the vehicle, it is larger and holds much more energy than batteries used to start conventional vehicles. Main stage: See through car with battery, engine, and electric motor visible. The car is stopped at an intersection.

9

Hybrid: Braking  

Alternative Fuels and Advanced Vehicles Data Center (EERE)

Button Stopped button highlighted subbanner graphic: gray bar Button Stopped button highlighted subbanner graphic: gray bar STOPPED When the vehicle is stopped, such as at a red light, the gasoline engine and electric motor shut off automatically so that energy is not wasted in idling. The battery continues to power auxillary systems, such as the air conditioning and dashboard displays. stage graphic: vertical blue rule Main stage: See through car with battery, engine, and electric motor visible. The car is stopped at an intersection. Main stage: See through car with battery, engine, and electric motor visible. The car is stopped at an intersection. Battery: The battery stores energy generated from the gasoline engine or, during regenerative braking, from the electric motor. Since the battery helps power the vehicle, it is larger and holds much more energy than batteries used to start conventional vehicles. Main stage: See through car with battery, engine, and electric motor visible. The car is stopped at an intersection.

10

Svendborg Brakes | Open Energy Information  

Open Energy Info (EERE)

Name: Svendborg Brakes Place: Denmark Sector: Wind energy Product: Denmark-based manufacturer of braking systems for the wind industry, as well as for the oil sector....

11

WIND BRAKING OF MAGNETARS  

SciTech Connect

We explore the wind braking of magnetars considering recent observations challenging the traditional magnetar model. There is evidence for strong multipole magnetic fields in active magnetars, but the dipole field inferred from spin-down measurements may be strongly biased by particle wind. Recent observations challenging the traditional model of magnetars may be explained naturally by the wind braking scenario: (1) the supernova energies of magnetars are of normal value; (2) the non-detection in Fermi observations of magnetars; (3) the problem posed by low magnetic field soft gamma-ray repeaters; (4) the relation between magnetars and high magnetic field pulsars; and (5) a decreasing period derivative during magnetar outbursts. Transient magnetars with L{sub x}<- E-dot{sub rot} may still be magnetic dipole braking. This may explain why low luminosity magnetars are more likely to have radio emissions. A strong reduction of the dipole magnetic field is possible only when the particle wind is very collimated at the star surface. A small reduction of the dipole magnetic field may result from detailed considerations of magnetar wind luminosity. In the wind braking scenario, magnetars are neutron stars with a strong multipole field. For some sources, a strong dipole field may no longer be needed. A magnetism-powered pulsar wind nebula will be one of the consequences of wind braking. For a magnetism-powered pulsar wind nebula, we should see a correlation between the nebula luminosity and the magnetar luminosity. Under the wind braking scenario, a braking index smaller than three is expected. Future braking index measurement of a magnetar may tell us whether magnetars are wind braking or magnetic dipole braking.

Tong, H. [Xinjiang Astronomical Observatory, Chinese Academy of Sciences, Urumqi, Xinjiang 830011 (China); Xu, R. X.; Qiao, G. J. [KIAA and School of Physics, Peking University, Beijing 100871 (China); Song, L. M., E-mail: tonghao@xao.ac.cn [Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049 (China)

2013-05-10T23:59:59.000Z

12

Chapter 9 - Brake Testing  

Science Journals Connector (OSTI)

Abstract This chapter describes and explains the role and methods of experimental testing in the design and verification of brakes and their components. It starts by discussing the increasing capability of computer-based predictive techniques, which can simulate many aspects of brake operation and save time and cost compared with previous methods of experimental evaluation. Preparation, procedures, instrumentation, data acquisition and results analysis, interpretation and reporting for experimental testing ranging from whole vehicle braking performance on a test track to component performance and material thermophysical properties in the laboratory, are explained and discussed. By the end of the chapter the design and operation of test rigs including inertia dynamometers for full-size brakes, scale rigs for small-sample friction and wear measurement, machines for cyclic loading and material property measurement, etc. are described. The importance of careful preparation of the friction pair (bedding-in and burnishing) for brake performance testing and the evaluation of variability by repeat testing is emphasised.

Andrew Day

2014-01-01T23:59:59.000Z

13

Solar tracker motor having a fixed caliper and a translating caliper each with an electromagnetic brake system  

DOE Patents (OSTI)

Concepts and technologies described herein provide for an accurate and cost-effective method for rotating a solar array disk for tracking the movement of the sun. According to various aspects, a motor includes a fixed caliper and a translating caliper positioned adjacent to one another. Electromagnetically controlled brakes on the translating caliper grip the solar array disk while adjacent, but spaced apart, electromagnets on the fixed caliper and the translating caliper are energized to create an attractive force that pulls the translating caliper with the solar array disk toward the fixed caliper. After reaching the fixed caliper, brakes on the fixed caliper are engaged with the disk, brakes on the translating caliper are released from the disk, and the translating caliper is pushed back to the starting location where the process repeats until the desired rotation is completed.

Rau, Scott James

2013-01-29T23:59:59.000Z

14

Modeling of air brakes for onboard diagnostics of heavy trucks  

E-Print Network (OSTI)

declared out of service. Worn brake pads and tires, air leaks at hoses, connections, valves and brake chambers of the airbrake system along with the significant time delay in the actuation of tractor and trailer brakes degrade the vehicle braking...

Kankanala, Penchala N

2012-06-07T23:59:59.000Z

15

Innovative vibration measurement technology for brake development  

Science Journals Connector (OSTI)

Apart from working reliably and providing safety, the comfort features of brakes in vehicles these days have become very significant. The requirement of a noiseless brake system always poses an important chall...

Dipl.-Ing. Holger Marschner; Dr. rer. nat. Dirk Reckwerth

2008-02-01T23:59:59.000Z

16

Heavy Overweight Vehicle Brake Testing (HOVBT)  

E-Print Network (OSTI)

Heavy Overweight Vehicle Brake Testing (HOVBT) Oak Ridge National Laboratory managed by UT for a real-time on-board brake assessment tool. Test Overview A combination tractor-trailer will be given a complete brake rebuild prior to several tests performed at fully -laden and several overweight loading

17

6 - Engine brake performance in diesel engine system design  

Science Journals Connector (OSTI)

Abstract: This chapter provides a comprehensive theory on engine brake performance. It first discusses vehicle braking requirement and the impact on enginevehicle matching in engine brake operation, followed by a comparison between engine brakes and drivetrain retarders. It then introduces drivetrain retarders in detail including their torque and cooling characteristics. The performance characteristics of exhaust brakes and compression brakes are elaborated including their mechanisms and the interactions with valvetrain, variable valve actuation (VVA) and turbocharger. The principles of engine brake design are introduced through comprehensive simulation analysis on engine thermodynamic cycles in braking operation. A braking gas recirculation (BGR) theory is developed.

Qianfan Xin

2013-01-01T23:59:59.000Z

18

Disturbance Control of the Hydraulic Brake in a Wind Turbine  

E-Print Network (OSTI)

Disturbance Control of the Hydraulic Brake in a Wind Turbine Frank Jepsen, Anders Søborg brake in a wind turbine. Brake torque is determined by friction coefficient and clamp force; the latter brake is one1 of the two independent brake systems in a wind turbine. As a consequence of the gearing

Yang, Zhenyu

19

Wide speed range for traction motor in braking force of electric braking control system  

Science Journals Connector (OSTI)

A vehicle stopping method using an electric brake until a traction motor is stopped is studied. At the moment of vehicle stop, electric brake is changed to control mode where ... is controlled by estimating the l...

Young-Choon Kim; Moon-Taek Cho

2014-10-01T23:59:59.000Z

20

Electric Braking Control System to Secure Braking Force in the Wide Speed Range of Traction Motor  

Science Journals Connector (OSTI)

In this paper, a vehicle stopping method using an electric brake until a traction motor is stopped is studied. At the moment of vehicle stop, electric brake is changed to control mode wherein ... is controlled by...

Young-Choon Kim; Moon-Taek Cho; Ok-Hwan Kim

2014-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "brakes front disk" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


21

PREDICTING RANGES FOR PULSARS' BRAKING INDICES  

SciTech Connect

The theoretical determination of braking indices of pulsars is still an open problem. In this paper we report results of a study concerning such determination based on a modification of the canonical model, which admits that pulsars are rotating magnetic dipoles, and on data from the seven pulsars with known braking indices. In order to test the modified model, we predict ranges for the braking indices of other pulsars.

Magalhaes, Nadja S.; Miranda, Thaysa A. [Federal University of Sao Paulo, DCET, Rua Sao Nicolau 210, Diadema, SP 09913-030 (Brazil); Frajuca, Carlos, E-mail: nadjasm@gmail.com [Federal Institute of Education, Science and Technology of Sao Paulo, R. Pedro Vicente 625, Sao Paulo, SP 01109-010 (Brazil)

2012-08-10T23:59:59.000Z

22

Hybrid Braking System for Non-Drive Axles  

Energy.gov (U.S. Department of Energy (DOE))

A hybrid braking system is designed to conserve diesel fuel (or alternative fuels) by using regenerative braking, which extends hybrid technology to non-drive axles.

23

TMV Technology Capabilities Brake Stroke Monitor  

E-Print Network (OSTI)

TMV Technology Capabilities Brake Stroke Monitor Brake monitoring systems are proactive maintenance This technology allows for CMV operators to have knowledge of their steer, drive, and tandem axle group weights setup is required. Current Safety/Enforcement Technologies EOBR (electronic on-board recorder) On

24

Chapter 6 - Brake System Layout Design  

Science Journals Connector (OSTI)

Abstract This chapter brings together high-level braking system design (Chapters 3 and 4Chapter 3Chapter 4) and the design of friction brakes (Chapter 5) to complete the layout design of road vehicle braking systems. Two actuation systems are studied: hydraulic (used on passenger cars and light commercial vehicles) and pneumatic (used on heavy commercial vehicles). Other braking technologies (e.g. regenerative) and actuation systems (e.g. power hydraulic and electromechanical) are also mentioned. A four-step design procedure is presented, which includes designing the basic braking system parameters based on the vehicle configuration, specifying the brakes (size and torque capacity), designing the actuation system, and verification (legislative requirements). Examples are presented for a hydraulic system with a vacuum booster (passenger car) and a pneumatic system (articulated commercial vehicle), which illustrate the important features of achieving a good basic system configuration. In passenger cars, the importance of driver interface parameters such as pedal feel is explained, and for commercial vehicles, compatibility, load sensing, and predominance between the trailer and towing vehicle brake systems is discussed.

Andrew Day

2014-01-01T23:59:59.000Z

25

Contactless magnetic brake for automotive applications  

E-Print Network (OSTI)

CONTACTLESS MAGNETIC BRAKE FOR AUTOMOTIVE APPLICATIONS A Dissertation by SEBASTIEN EMMANUEL GAY Submitted to the Office of Graduate Studies of Texas A&M University in partial fulfillment of the requirements for the degree of DOCTOR... OF PHILOSOPHY May 2005 Major Subject: Electrical Engineering CONTACTLESS MAGNETIC BRAKE FOR AUTOMOTIVE APPLICATIONS A Dissertation by SEBASTIEN EMMANUEL GAY Submitted to Texas A&M University in partial fulfillment of the requirements...

Gay, Sebastien Emmanuel

2009-05-15T23:59:59.000Z

26

Adaptive controller for regenerative and friction braking system  

DOE Patents (OSTI)

A regenerative and friction braking system for a vehicle having one or more roadwheels driven by an electric traction motor includes a driver responsive device for producing a brake demand signal having a magnitude corresponding to the level of braking force selected by the driver and friction and regenerative brakes operatively connected with the roadwheels of the vehicle. A system according to this invention further includes control means for operating the friction and regenerative braking subsystems so that maximum brake torques sustainable by the roadwheels of the vehicle without skidding or slipping will not be exceeded.

Davis, Roy I. (Ypsilanti, MI)

1990-01-01T23:59:59.000Z

27

The braking performance of tractor-trailer combinations  

Science Journals Connector (OSTI)

Equations are derived for the maximum decelerations which can be obtained with balanced and unbalanced trailers with and without trailer brakes. The equations are used to produce graphs showing the maximum decelerations of trailers having typical dimensions, of different weights relative to the towing tractor on surfaces of different adhesion coefficients and with different types and degrees of braking on the trailers. Results measured during braking tests on tractors and trailers are given. Unbalanced trailers are shown to have a better braking performance than balanced trailers and it is therefore, recommended that trailers should be designed to carry the maximum permissible proportion of their weight on the tractor. Both over-run and power brakes on trailers are shown to provide very useful improvements in braking performance. Power brakes are preferred because of the difficulty of fitting over-run brakes on unbalanced trailers. The tractor's external hydraulics are considered to be the most convenient source of power. On-off brakes providing a fixed braking force equal to approximately 510% of the trailer maximum gross laden weight are considered to be a useful and simple means of improving existing trailers, but the development of trailer braking systems providing a braking force proportional to the tractor brake pedal force up to a maximum of approximately 2030% of the trailer maximum gross laden weight is considered to be very desirable.

M.J. Dwyer

1970-01-01T23:59:59.000Z

28

Thermal cracking in disc brakes Thomas J. Mackin *,1  

E-Print Network (OSTI)

Thermal cracking in disc brakes Thomas J. Mackin *,1 , Steven C. Noe, K.J. Ball, B.C. Bedell, D, or hub, which is connected to the wheel and axle, and an inboard and outboard braking surface

Salvaggio, Carl

29

Electric vehicle regenerative antiskid braking and traction control system  

DOE Patents (OSTI)

An antiskid braking and traction control system for an electric or hybrid vehicle having a regenerative braking system operatively connected to an electric traction motor, and a separate hydraulic braking system includes one or more sensors for monitoring present vehicle parameters and a processor, responsive to the sensors, for calculating vehicle parameters defining the vehicle behavior not directly measurable by the sensors and determining if regenerative antiskid braking control, requiring hydrualic braking control, or requiring traction control are required. The processor then employs a control strategy based on the determined vehicle state and provides command signals to a motor controller to control the operation of the electric traction motor and to a brake controller to control fluid pressure applied at each vehicle wheel to provide the appropriate regenerative antiskid braking control, hydraulic braking control, and traction control.

Cikanek, Susan R. (Wixom, MI)

1995-01-01T23:59:59.000Z

30

A diagnostic system for air brakes in commercial vehicles  

E-Print Network (OSTI)

This dissertation deals with the development of a model-based diagnostic system for air brake systems that are widely used in commercial vehicles, such as trucks, tractor-trailers, buses, etc. The performance of these brake systems is sensitive...

Coimbatore Subramanian, Shankar Ram

2007-09-17T23:59:59.000Z

31

Airborne wear particles railway research group FEM Simulation of train disc brake behavior  

E-Print Network (OSTI)

1 Airborne wear particles railway research group FEM Simulation of train disc brake behavior a modern train disc brake with brake caliper and high speed pads. During braking, a considerable amount. A model of train brake caliper Aim The overall aim of the MSc degree project is to develop a thermoelastic

Haviland, David

32

Development of Diagnostic Algorithms for Air Brakes in Trucks  

E-Print Network (OSTI)

for di erent clearances and supply pressures : : : 6 4 Modes of operation of the air brake system [19] : : : : : : : : : : : : 11 5 A simpli ed layout of air brake system for a tractor : : : : : : : : : : 15 6 S-cam foundation brake..., causing it to rotate the slack adjuster. The slack adjuster, in turn, rotates 15 Fig. 5. A simpli ed layout of air brake system for a tractor the S-cam as it is connected to the S-cam through a splined shaft. The rotational mo- tion of the S-cam pushes...

Dhar, Sandeep

2011-10-21T23:59:59.000Z

33

Measurement and control of brake pedal feel quality in automobile manufacturing  

E-Print Network (OSTI)

Customer perception of brake pedal feel quality, as related to the perception of the brake pedal feeling soft or mushy, depends on both the customer's subjective judgment of quality and the actual build quality of the brake ...

Cerilles, Jeffrey T. (Jeffrey Thomas)

2005-01-01T23:59:59.000Z

34

E-Print Network 3.0 - air brakes Sample Search Results  

NLE Websites -- All DOE Office Websites (Extended Search)

brakes to predominantly air disc brakes. Compare and contrast the impact of such conversions in Europe... Energy Efficiency in Heavy Vehicle Tires, Drivetrains, and ......

35

E-Print Network 3.0 - antilock brake systems Sample Search Results  

NLE Websites -- All DOE Office Websites (Extended Search)

such as trucks, tractor... -trailers and buses. In these brake systems, compressed air is used as the energy transmitting medium to actuate... the foundation brakes mounted...

36

E-Print Network 3.0 - anti-lock braking system Sample Search...  

NLE Websites -- All DOE Office Websites (Extended Search)

such as trucks, tractor... -trailers and buses. In these brake systems, compressed air is used as the energy transmitting medium to actuate... the foundation brakes mounted...

37

A pressure control scheme for air brakes in commercial vehicles  

E-Print Network (OSTI)

This research is focused on developing a control scheme for regulating the pressure in the brake chamber of an air brake system found in most commercial vehicles like trucks, tractor-trailers and buses. Such a control scheme can be used...

Bowlin, Christopher Leland

2007-04-25T23:59:59.000Z

38

Many applications require brakes, for instance to decelerate or to  

E-Print Network (OSTI)

surfaces in order to generate the braking torque. Typically, actuators Statically balancing A team of TU an error occurs in the process of a robotic arm. The energy consumption and actuation force of these brakes is very high. A team of TU Delft scientists developed a method to reduce the energy consumption

39

Investigation of aerodynamic braking devices for wind turbine applications  

SciTech Connect

This report documents the selection and preliminary design of a new aerodynamic braking system for use on the stall-regulated AWT-26/27 wind turbines. The goal was to identify and design a configuration that offered improvements over the existing tip brake used by Advanced Wind Turbines, Inc. (AWT). Although the design objectives and approach of this report are specific to aerodynamic braking of AWT-26/27 turbines, many of the issues addressed in this work are applicable to a wider class of turbines. The performance trends and design choices presented in this report should be of general use to wind turbine designers who are considering alternative aerodynamic braking methods. A literature search was combined with preliminary work on device sizing, loads and mechanical design. Candidate configurations were assessed on their potential for benefits in the areas of cost, weight, aerodynamic noise, reliability and performance under icing conditions. As a result, two configurations were identified for further study: the {open_quotes}spoiler-flap{close_quotes} and the {open_quotes}flip-tip.{close_quotes} Wind tunnel experiments were conducted at Wichita State University to evaluate the performance of the candidate aerodynamic brakes on an airfoil section representative of the AWT-26/27 blades. The wind tunnel data were used to predict the braking effectiveness and deployment characteristics of the candidate devices for a wide range of design parameters. The evaluation was iterative, with mechanical design and structural analysis being conducted in parallel with the braking performance studies. The preliminary estimate of the spoiler-flap system cost was $150 less than the production AWT-26/27 tip vanes. This represents a reduction of approximately 5 % in the cost of the aerodynamic braking system. In view of the preliminary nature of the design, it would be prudent to plan for contingencies in both cost and weight.

Griffin, D.A. [R. Lynette & Associates, Seattle, WA (United States)

1997-04-01T23:59:59.000Z

40

Disk filter  

DOE Patents (OSTI)

An electric disk filter provides a high efficiency at high temperature. A hollow outer filter of fibrous stainless steel forms the ground electrode. A refractory filter material is placed between the outer electrode and the inner electrically isolated high voltage electrode. Air flows through the outer filter surfaces through the electrified refractory filter media and between the high voltage electrodes and is removed from a space in the high voltage electrode.

Bergman, W.

1985-01-09T23:59:59.000Z

Note: This page contains sample records for the topic "brakes front disk" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


41

Modeling the pneumatic relay valve of an s-cam air brake  

E-Print Network (OSTI)

Statistics indicate that defects in brake system contribute significantly to fatal crashes involving commercial vehicles. Hence there is a need for developing preventive and active safety measures for assessing the performance of an air brake system...

Vilayannur Natarajan, Shankar

2005-08-29T23:59:59.000Z

42

Fuzzy logic electric vehicle regenerative antiskid braking and traction control system  

DOE Patents (OSTI)

An regenerative antiskid braking and traction control system using fuzzy logic for an electric or hybrid vehicle having a regenerative braking system operatively connected to an electric traction motor, and a separate hydraulic braking system includes sensors for monitoring present vehicle parameters and a processor, responsive to the sensors, for calculating vehicle parameters defining the vehicle behavior not directly measurable by the sensor and determining if regenerative antiskid braking control, requiring hydraulic braking control, and requiring traction control are required. The processor then employs fuzzy logic based on the determined vehicle state and provides command signals to a motor controller to control operation of the electric traction motor and to the brake controller to control fluid pressure applied at each vehicle wheel to provide the appropriate regenerative braking control, hydraulic braking control, and traction control.

Cikanek, Susan R. (Wixom, MI)

1994-01-01T23:59:59.000Z

43

Evaluation of driver braking performance to an unexpected object in the roadway  

E-Print Network (OSTI)

components, specifically whether the equation accurately reflects driver and vehicle behaviors during a braking maneuver. This research evaluated the two components of the SSD equation. Four field studies were conducted that evaluated driver braking...

Picha, Dale Louis

2012-06-07T23:59:59.000Z

44

Cybersecurity Front Burner | Department of Energy  

Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

Awareness Program Cybersecurity Front Burner Cybersecurity Front Burner Documents Available for Download November 1, 2014 FRONT BURNER - ISSUE 19 The Cybersecurity Front Burner...

45

E-Print Network 3.0 - air brake association Sample Search Results  

NLE Websites -- All DOE Office Websites (Extended Search)

... Source: Southwest Region University Transportation Center Collection: Engineering ; Energy Storage, Conversion and Utilization 2 Commercial Motor Vehicle Brake Assessment...

46

Switched reluctance motor based electromechanical brake-by-wire system  

Science Journals Connector (OSTI)

This article presents an overview of electronic braking systems using SR (Switched Reluctance) machines. The advantages presented by this structure when compared to the conventional hydraulic systems are discussed. A justification for the choice of the SRM as a valid candidate is provided, with a detailed analysis of its control structure and performance. Experimental results obtained using a digital signal processor are also presented.

S. Underwood; A. Khalil; I. Husain; H. Klode; B. Lequesne; S. Gopalakrishnan; A. Omekanda

2004-01-01T23:59:59.000Z

47

A mathematical model for air brake systems in the presence of leaks  

E-Print Network (OSTI)

model for an air brake system in the presence of leaks. Brake systems in trucks are crucial for ensuring the safety of vehicles and passengers on the roadways. Most trucks in the US are equipped with S-cam drum brake systems and they are sensitive.... Overview Air brake systems are used in heavy commercial vehicles like buses, straight trucks and combination vehicles such as tractor-trailers[1]. More than 85% of the commer- cial vehicles in the US are equipped with S-cam drum brakes[2]. Proper...

Ramaratham, Srivatsan

2008-10-10T23:59:59.000Z

48

Design and test of a wet type helium turbo-expander with an alternator as a brake  

SciTech Connect

A wet type helium turbo-expander with expected adiabatic efficiency of 70% at inlet pressure, temperature, and outlet pressure of 1.3 MPa, 6.0 K, and 0.2 MPa, respectively, has been developed. An alternator is adopted as a brake where a permanent magnet is held in the turbine shaft. And a self-acting gas bearing is used at thrust and journal bearings. An electromagnet supports thrust bearing to lift up the thrust disk when initiating operation. Design mass flow rate of the turbine is determined to be 60 g/s, corresponding to the JT mass flow rate in the existing helium liquefier/refrigerator. In the cryogenic performance test, the turbine had increased helium liquefaction rate by four times larger than the liquefaction rate without turbine operation.

Kato, T.; Miyake, A.; Kawano, K.; Hamada, K.; Hiyama, T.; Iwamoto, S.; Ebisu, H.; Tsuji, H. [Japan Atomic Energy Research Institute, Ibaraki-ken (Japan); Saji, N.; Kaneko, Y. [Ishikawajima-Harima Heavy Industries Co. Ltd., Tokyo (Japan)] [and others

1994-12-31T23:59:59.000Z

49

E-Print Network 3.0 - automatic braking Sample Search Results  

NLE Websites -- All DOE Office Websites (Extended Search)

for an Urban Electric Vehicle Summary: , Automatic Braking, Electric Vehicles, Personal Rapid Transit, Public Transit, Advanced Vehicle Control... the design modification,...

50

E-Print Network 3.0 - automotive brake materials Sample Search...  

NLE Websites -- All DOE Office Websites (Extended Search)

such as trucks, tractor... -trailers and buses. In these brake systems, compressed air is used as the energy transmitting medium to ... Source: Southwest Region University...

51

Modeling the pneumatic subsystem of a S-cam air brake system  

E-Print Network (OSTI)

The air brake system is one of the critical components in ensuring the safe operation of any commercial vehicle. This work is directed towards the development of a fault-free model of the pneumatic subsystem of the air brake system. This model can...

Coimbatore Subramanian, Shankar

2004-09-30T23:59:59.000Z

52

Vehicle yaw control via coordinated use of steering/braking systems  

E-Print Network (OSTI)

Vehicle yaw control via coordinated use of steering/braking systems M. Doumiati, O. Sename, J. Martinez, L. Dugard P. Gaspar, Z. Szabo, J. Bokor Gipsa-Lab UMR CNRS 5216, Control Systems Department with steer- ing/braking coordination task for vehicle yaw control. For steerability enhancement, only active

Paris-Sud XI, Université de

53

Fault tolerant control of automatically controlled vehicles in response to brake system failures  

E-Print Network (OSTI)

in the brake system is vital. In this thesis, nonlinear failure detection filters are used for fault detection of sensors and actuators in a class of nonlinear systems. In this thesis, the effects of brake system failures in an AHS where the vehicle steering...

Hsien, Li-Wei

2012-06-07T23:59:59.000Z

54

Plant and Environment Interactions Arsenic Accumulation in the Hyperaccumulator Chinese Brake and Its Utilization  

E-Print Network (OSTI)

in a greenhouse. At recently, however, has Chinese brake (Pteris vittata L.)harvest, the Chinese brake produced soils (0.47­7.56 mg As kg 1 ),concentration to water-soluble arsenic in soil) of 1450 and a transloca to remediate arsenic contaminated soils. schullat, 2000), soil arsenic concentration (Jiang and Singh, 1994

Ma, Lena

55

Microsoft PowerPoint - Real-Time Dynamic Brake Assessment poster.ppt [Compatibility Mode]  

NLE Websites -- All DOE Office Websites (Extended Search)

Dynamic Brake Assessment Dynamic Brake Assessment Purpose Conduct a proof-of-concept test to examine the feasibility of developing an on-board system to assess a vehicle's ability to stop based on typical low-pressure in-service braking events. Partnerships H.T. Hackney Company MGM Brakes Overview Funded through the Federal Motor Carrier Safety Administration's Vehicle and Roadside Operations Division Concept stemming from on the Department of Energy's Medium Truck Duty Cycle research as well as previous research conducted for the National Highway Transportation Safety Administration. Signals to be collected Real-time brake application pressure Vehicle speed and acceleration GPS location and grade information Vehicle weight (current load) Engine parameters such as RPM and torque To be conducted October 2010 -

56

Disk Quota Increase Request  

NLE Websites -- All DOE Office Websites (Extended Search)

Disk Disk Quota Increase Disk Quota Increase Request NERSC will consider reasonable requests for changes in disk space and inode limits. Please submit a request through the "Request Forms" section at the NERSC help portal. If you select "Hopper scratch directory" from the "File System" menu below, the quota value requested applies to the combined contents of $SCRATCH and $SCRATCH2. Please ask for the least amount of resources you need, since the sum of disk space and inodes allocated to users already exceeds system capacity. In other words, system resources would be exhausted before all users could use their existing quotas. You can find out the current quotas and usage of disk space and inodes for your home and scratch file systems with the myquota command. You can find

57

Wind turbine trailing-edge aerodynamic brake design  

SciTech Connect

This report describes the design of a centrifugally actuated aerodynamic-overspeed device for a horizontal-axis wind turbine. The device will meet the following criteria; (1) It will be effective for airfoil angles of attack 0{degrees} to 45{degrees}. (2) It will be stowed inside the blade profile prior to deployment. (3) It will be capable of offsetting the positive torque produced by the overall blade. (4) Hinge moments will be minimized to lower actuator loads and cost. (5) It will be evaluated as a potential power modulating active rotor-control system. A literature review of aerodynamic braking devices was conducted. Information from the literature review was used to conceptualize the most effective devices for subsequent testing and design. Wind-tunnel test data for several braking devices are presented in this report. Using the data for the most promising configuration, a preliminary design was developed for a MICON 65/13 wind turbine with Phoenix 7.9-m rotor blades.

Quandt, G.

1996-01-01T23:59:59.000Z

58

Glass rupture disk  

DOE Patents (OSTI)

A frangible rupture disk and mounting apparatus for use in blocking fluid flow, generally in a fluid conducting conduit such as a well casing, a well tubing string or other conduits within subterranean boreholes. The disk can also be utilized in above-surface pipes or tanks where temporary and controllable fluid blockage is required. The frangible rupture disk is made from a pre-stressed glass with controllable rupture properties wherein the strength distribution has a standard deviation less than approximately 5% from the mean strength. The frangible rupture disk has controllable operating pressures and rupture pressures.

Glass, S. Jill (Albuquerque, NM); Nicolaysen, Scott D. (Albuquerque, NM); Beauchamp, Edwin K. (Albuquerque, NM)

2002-01-01T23:59:59.000Z

59

FRONT BURNER - ISSUE 19 | Department of Energy  

Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

FRONT BURNER - ISSUE 19 FRONT BURNER - ISSUE 19 The Cybersecurity Front Burner Issue No. 19 is the campaign newsletter for the 2014 DOE NCSAM event. The newsletter addresses the...

60

Front Burner - Issue 18 | Department of Energy  

Energy Savers (EERE)

Front Burner - Issue 18 Front Burner - Issue 18 The Cybersecurity Front Burner Issue No. 18 addresses keeping kids safe on the Internet, cyber crime, and DOE Cyber awareness and...

Note: This page contains sample records for the topic "brakes front disk" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


61

The Magnetic Field in the Class 0 Protostellar Disk of L1527  

E-Print Network (OSTI)

We present subarcsecond (~0.35") resolved observations of the 1.3 mm dust polarization from the edge-on circumstellar disk around the Class 0 protostar L1527. The inferred magnetic field is consistent with a dominantly toroidal morphology; there is no significantly detected vertical poloidal component to which observations of an edge-on disk are most sensitive. This suggests that angular momentum transport in Class 0 protostars (when large amounts of material are fed down to the disk from the envelope and accreted onto the protostar) is driven mainly by magnetorotational instability rather than magnetocentrifugal winds at 50 AU scales. In addition, with the data to date there is an early, tentative trend that R>30 AU disks have so far been found in Class 0 systems with average magnetic fields on the 1000 AU scale strongly misaligned with the rotation axis. The absence of such a disk in the aligned case could be due to efficient magnetic braking that disrupts disk formation. If this is the case, this implies t...

Segura-Cox, Dominique M; Stephens, Ian W; Fernandez-Lopez, Manuel; Kwon, Woojin; Tobin, John J; Li, Zhi-Yun; Crutcher, Richard

2014-01-01T23:59:59.000Z

62

Front Burner - Issue 13 | Department of Energy  

Energy.gov (U.S. Department of Energy (DOE)) Indexed Site

3 Front Burner - Issue 13 The Cybersecurity Front Burner Issue No. 13 contained a message from the Associate Chief Information Officer (ACIO) for Cybersecurity informing readers...

63

Front Burner - Issue 14 | Department of Energy  

Energy.gov (U.S. Department of Energy (DOE)) Indexed Site

4 Front Burner - Issue 14 The Cybersecurity Front Burner Issue No. 14 addresses the 2013 National Cybersecurity Awareness Month (NCSAM) Campaign and Phishing Scams. Cybersecurity...

64

Effect of Nanoclay Reinforcement on the Friction Braking Performance of Hybrid Phenolic Friction Composites  

Science Journals Connector (OSTI)

Friction composite formulation consisting of decreasing nanoclay/lapinus fibres content, increasing graphite/aramid fibres ... is adopted for evaluating braking performance. The nanoclay content (?2.25wt.%) enha...

Tej Singh; Amar Patnaik

2013-03-01T23:59:59.000Z

65

Achieving Consistent Maximum Brake Torque with Varied Injection Timing in a DI Diesel Engine  

E-Print Network (OSTI)

, the characteristics of combustion for swept injection timings along the maximum brake torque plateau are determined. The research is conducted by varying injection timing at constant engine speed and load while measuring engine emissions and in-cylinder pressure...

Kroeger, Timothy H

2013-09-19T23:59:59.000Z

66

RO-VIBRATIONAL CO DETECTED IN THE {beta} PICTORIS CIRCUMSTELLAR DISK  

SciTech Connect

We present high-resolution near-infrared spectra of {beta} Pictoris-a nearby young star with a debris disk. Fundamental low-J CO absorption lines are detected and strict upper limits are placed on the flux of v = 2-1 low-J CO emission lines. The limit on the UV fluorescent emission flux in the v = 2-1 lines is used to place a tight constraint on the inner extent of the CO gas. Assuming H I is the primary collision partner, the sub-thermal population of the low-J v = 0 rotational levels constrains the density of the gas in the disk to n{sub H} = (2.5{sup +7.1}{sub -1.2}) x 10{sup 5} cm{sup -3}. If the distribution of hydrogen follows that of the other metals in the disk, we find that the mass of the gas in the disk is 0.17{sup +0.47}{sub -0.08} M{sub +}. We compare this mass to the gas mass necessary to brake the metals in the disk through ion-neutral reactions.

Troutman, Matthew R. [Department of Physics and Astronomy, University of Missouri-St. Louis, 8001 Natural Bridge Road, St. Louis, MO 63121 (United States); Hinkle, Kenneth H.; Najita, Joan R. [National Optical Astronomy Observatory, 950 North Cherry Avenue, Tucson, AZ 85719 (United States); Rettig, Terrence W. [Center for Astrophysics, University of Notre Dame, Notre Dame, IN 46556 (United States); Brittain, Sean D., E-mail: mtroutm@clemson.edu, E-mail: khinkle@noao.edu, E-mail: najita@noao.edu, E-mail: trettig@nd.edu, E-mail: sbritt@clemson.edu [Department of Physics and Astronomy, 118 Kinard Laboratory, Clemson University, Clemson, SC 29634 (United States)

2011-09-01T23:59:59.000Z

67

Premixed direct injection disk  

DOE Patents (OSTI)

A fuel/air mixing disk for use in a fuel/air mixing combustor assembly is provided. The disk includes a first face, a second face, and at least one fuel plenum disposed therebetween. A plurality of fuel/air mixing tubes extend through the pre-mixing disk, each mixing tube including an outer tube wall extending axially along a tube axis and in fluid communication with the at least one fuel plenum. At least a portion of the plurality of fuel/air mixing tubes further includes at least one fuel injection hole have a fuel injection hole diameter extending through said outer tube wall, the fuel injection hole having an injection angle relative to the tube axis. The invention provides good fuel air mixing with low combustion generated NOx and low flow pressure loss translating to a high gas turbine efficiency, that is durable, and resistant to flame holding and flash back.

York, William David; Ziminsky, Willy Steve; Johnson, Thomas Edward; Lacy, Benjamin; Zuo, Baifang; Uhm, Jong Ho

2013-04-23T23:59:59.000Z

68

Fuel for Galaxy Disks  

E-Print Network (OSTI)

Halo clouds have been found about the three largest galaxies of the Local Group and in the halos of nearby spirals. This suggests they are a relatively generic feature of the galaxy evolution process and a source of fuel for galaxy disks. In this review, two main sources of disk star formation fuel, satellite material and clouds condensing from the hot halo medium, are discussed and their contribution to fueling the Galaxy quantified. The origin of the halo gas of M31 and M33 is also discussed.

M. E. Putman; J. Grcevich; J. E. G. Peek

2008-03-20T23:59:59.000Z

69

Low frequency vibrations in disc brakes at high car speed. Part II: mathematical model and simulation  

Science Journals Connector (OSTI)

In the present paper, a mathematical model is constructed for judder in disc brakes at high speed. Vehicle suspension is modelled by means of finite elements. Vibration modes and frequencies are derived that can be used in the classification of modes in main and secondary based in the relative disc-calliper displacement; the finite element model is also used as well as in forced-response analysis. Brake pads are defined through the friction coefficient as a function of speed, pressure, and temperature, in light of which one may consider the various braking conditions and types of pad. Since the line of reasoning introduces equivalent-damping terms into the equations of dynamics, these equations cannot be uncoupled by means of modal transformation. Two techniques are proposed for the solution of the problem. One of these consists in an examination of the 'main-modes', while the other is based on direct integration of the quasi-uncoupled equations. A computer program has been implemented which allows the simulation of this kind of judder with different pads, brake systems and braking conditions.

R. Aviles; G. Hennequet; E. Amezua; J. Vallejo

1995-01-01T23:59:59.000Z

70

Disk Roughness and Defect Monitoring  

Science Journals Connector (OSTI)

Disk surface monitoring and certification refer to the testing and certification of a disk surface in terms of roughness and defect ... as well as the capability to accommodate a flying slider. It includes glide ...

Gang Sheng; Jizhong He; Shuanlin Duan

2013-01-01T23:59:59.000Z

71

Erasable digital audio disk system  

Science Journals Connector (OSTI)

Following the popularization of the compact disc, much attention has been paid to development of an erasable optical disk. A magnetooptical disk has proved the most useful in our...

Torazawa, Kenji; Sumi, Satoshi; Murata, Seiji; Minechika, Shigekazu; Ishii, Yasuhiro

1986-01-01T23:59:59.000Z

72

Extremal black disks in QCD  

E-Print Network (OSTI)

We argue that in the high energy QCD a true black disk wave function necessarily contains many quarks. This corresponds to necessity of non-vacuum reggeon loops in formation of a black disk. The result comes from decomposition of the black disk S-matrix in characters on group manifold.

Alexey V. Popov

2008-05-12T23:59:59.000Z

73

Compliant mechanism road bicycle brake: a rigid-body replacement case study  

SciTech Connect

The design of high-performance bicycle brakes is complicated by the competing design objectives of increased performance and low weight. But this challenge also provides a good case study to demonstrate the design of compliant mechanisms to replace current rigid-link mechanisms. This paper briefly reviews current road brake designs, demonstrates the use of rigid-body replacement synthesis to design a compliant mechanism, and illustrates the combination of compliant mechanism design tools. The resulting concept was generated from the modified dual-pivot brake design and is a partially compliant mechanism where one pin has the dual role of a joint and a mounting pin. The pseudo-rigid-body model, finite element analysis, and optimization algorithms are used to generate design dimensions, and designs are considered for both titanium and E-glass flexures. The resulting design has the potential of reducing the part count and overall weight while maintaining a performance similar to the benchmark.

Olsen, Brian M [Los Alamos National Laboratory; Howell, Larry L [NON LANL; Magleby, Spencer P [NON LANL

2011-01-19T23:59:59.000Z

74

Front Burner - Issue 16 | Department of Energy  

Energy.gov (U.S. Department of Energy (DOE)) Indexed Site

6 Front Burner - Issue 16 The Cybersecurity Front Burner Issue No. 16 addresses Malware, the Worst Passwords of 2013, and the Flat Stanley and Stop.Think.Connect. Campaign....

75

Magnesium Front End Design and Development  

Energy.gov (U.S. Department of Energy (DOE)) Indexed Site

by: Alan A. Luo and R. C. McCune Presented by: James Quinn, General Motors Unibody Architecture 3-piece Mg front end (bodyframe) USAMP AMD 603 - Magnesium Front End Design and...

76

Operations & Maintenance Best Practices Guide: Front Matter  

Energy.gov (U.S. Department of Energy (DOE))

Guide describes the front matter of the Operations and Maintenance Best Practices: a Guide to Achieving Operational Efficiency.

77

Poiseuille Advection of Chemical Reaction Fronts  

Science Journals Connector (OSTI)

Poiseuille flow between parallel plates alters the shapes and velocities of chemical reaction fronts. In the narrow-gap limit, the cubic reaction-diffusion-advection equation predicts a front-velocity correction equal to the gap-averaged fluid velocity ?. In the singular wide-gap limit, the correction equals the midgap fluid velocity 3?/2 when the flow is in the direction of propagation of the reaction front, and equals zero for adverse flow of any amplitude for which the front has a midgap cusp. Stationary fronts are possible only for adverse flow and finite gaps. Experiments are suggested.

Boyd F. Edwards

2002-08-16T23:59:59.000Z

78

front  

NLE Websites -- All DOE Office Websites (Extended Search)

Carbon Carbon Carbon Sequestration Sequestration State of the Science roadmapping future carbon sequestration R&D February 1999 A working paper for U.S. Department of Energy Office of Science Office of Fossil Energy i Carbon Sequestration DRAFT (February 1999) Dave Reichle, ORNL John Houghton, DOE Sally Benson, LBNL John Clarke, PNNL Roger Dahlman, DOE George Hendrey, BNL Howard Herzog, MIT Jennie Hunter-Cevera, LBNL Gary Jacobs, ORNL Rod Judkins, ORNL WORKING PAPER ON CARBON SEQUESTRATION SCIENCE AND TECHNOLOGY Office of Science Office of Fossil Energy U.S. Department of Energy Bob Kane, DOE Jim Ekmann, FETC Joan Ogden, Princeton Anna Palmisano, DOE Robert Socolow, Princeton John Stringer, EPRI Terry Surles, LLNL Alan Wolsky, ANL Nicholas Woodward, DOE Michael York, DOE ii DRAFT (February 1999) Carbon Sequestration

79

Genetic programming approach to predict torque and brake specific fuel consumption of a gasoline engine  

Science Journals Connector (OSTI)

This study presents genetic programming (GP) based model to predict the torque and brake specific fuel consumption a gasoline engine in terms of spark advance, throttle position and engine speed. The objective of this study is to develop an alternative robust formulations based on experimental data and to verify the use of GP for generating the formulations for gasoline engine torque and brake specific fuel consumption. Experimental studies were completed to obtain training and testing data. Of all 81 data sets, the training and testing sets consisted of randomly selected 63 and 18 sets, respectively. Considerable good performance was achieved in predicting gasoline engine torque and brake specific fuel consumption by using GP. The performance of accuracies of proposed GP models are quite satisfactory (R2=0.9878 for gasoline engine torque and R2=0.9744 for gasoline engine brake specific fuel consumption). The prediction of proposed GP models were compared to those of the neural network modeling, and strictly good agreement was observed between the two predictions. The proposed GP formulation is quite accurate, fast and practical.

Necla Togun; Sedat Baysec

2010-01-01T23:59:59.000Z

80

Real-Time Dynamic Brake Assessment Conduct a proof-of-concept  

E-Print Network (OSTI)

Real-Time Dynamic Brake Assessment Purpose Conduct a proof-of-concept test to examine the Federal Motor Carrier Safety Administration's Vehicle and Roadside Operations Division Concept stemming conducted for the National Highway Transportation Safety Administration. Signals to be collected Real

Note: This page contains sample records for the topic "brakes front disk" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


81

Dynamical Evolution of Protoplanetary Disks  

E-Print Network (OSTI)

This paper reviews the theory of protostellar debris disks. After a brief introduction to accretion disk physics, I describe coagulation models of planet formation in the outer regions of planetesimal disks. Coagulation models for the Kuiper Belt produce Pluto-sized objects on timescales of 10-40 Myr. These models yield size distributions which agree with observations of Kuiper Belt objects with red magnitudes, R = 20-27. Velocity stirring models for other debris disk systems demonstrate that 500 km or larger objects can stir the velocities of small objects up to the shattering limit needed to begin a collisional cascade.

Scott J. Kenyon

2000-10-02T23:59:59.000Z

82

Mechanically versus electro-magnetically braked cycle ergometer: performance and energy cost of the Wingate Anaerobic Test  

Science Journals Connector (OSTI)

Performance and metabolic profiles of the Wingate Anaerobic Test (WAnT) were compared between a mechanically resisted (ME) and an electro-magnetically braked (EE) cycle ergometer. Fifteen healthy subjects (24....

D. Micklewright; A. Alkhatib; R. Beneke

2006-04-01T23:59:59.000Z

83

The effectiveness of using the calculated braking current for longitudinal differential protection of 110 - 750 kV shunt reactors  

SciTech Connect

The use of the function of effective current braking of the longitudinal differential protection of shunt reactors to offset current surges, which enables the sensitivity of differential protection to be increased when there are short circuits with low damage currents, is considered. It is shown that the use of the calculated braking characteristic enables the reliability of offset protection from transients to be increased when the reactor is connected, which is accompanied by the flow of asymmetric currents containing an aperiodic component.

Vdovin, S. A. [JSC 'E and E' (Russian Federation); Shalimov, A. S. [LLC Selekt Co. (Russian Federation)

2013-05-15T23:59:59.000Z

84

Stability of cosmological detonation fronts  

E-Print Network (OSTI)

The steady state propagation of a phase transition front is classified, according to hydrodynamics, as a deflagration or a detonation, depending on its velocity with respect to the fluid. These propagation modes are further divided into three types, namely, weak, Jouguet, and strong solutions, according to their disturbance of the fluid. However, some of these hydrodynamic modes will not be realized in a phase transition. One particular cause is the presence of instabilities. In this work we study the linear stability of weak detonations, which are generally believed to be stable. After discussing in detail the weak detonation solution, we consider small perturbations of the interface and the fluid configuration. When the balance between the driving and friction forces is taken into account, it turns out that there are actually two different kinds of weak detonations, which behave very differently as functions of the parameters. We show that the branch of stronger weak detonations are unstable, except very cl...

Megevand, Ariel

2014-01-01T23:59:59.000Z

85

Nonlinear analysis of time series of vibration data from a friction brake: SSA, PCA, and MFDFA  

E-Print Network (OSTI)

We use the methodology of singular spectrum analysis (SSA), principal component analysis (PCA), and multi-fractal detrended fluctuation analysis (MFDFA), for investigating characteristics of vibration time series data from a friction brake. SSA and PCA are used to study the long time-scale characteristics of the time series. MFDFA is applied for investigating all time scales up to the smallest recorded one. It turns out that the majority of the long time-scale dynamics, that is presumably dominated by the structural dynamics of the brake system, is dominated by very few active dimensions only and can well be understood in terms of low dimensional chaotic attractors. The multi-fractal analysis shows that the fast dynamical processes originating in the friction interface are in turn truly multi-scale in nature.

Nikolay K. Vitanov; Norbert P. Hoffmann; Boris Wernitz

2014-10-23T23:59:59.000Z

86

Resonant relaxation in protoplanetary disks  

E-Print Network (OSTI)

Resonant relaxation is a novel form of two-body relaxation that arises in nearly Keplerian disks such as protoplanetary disks. Resonant relaxation does not affect the semimajor axes of the particles, but enhances relaxation of particle eccentricities and inclinations. The equilibrium state after resonant relaxation is a Rayleigh distribution, with the mean-square eccentricity and inclination inversely proportional to mass. The rate of resonant relaxation depends strongly on the precession rate of the disk. If the precession due to the disk's self-gravity is small compared to the total precession, then the relaxation is concentrated near the secular resonance between each pair of interacting bodies; on the other hand if the precession rate is dominated by the disk's self-gravity then relaxation occurs through coupling to the large-scale low-frequency m=1 normal modes of the disk. Depending on the disk properties, resonant relaxation may be either stronger or weaker than the usual non-resonant relaxation.

Scott Tremaine

1998-05-27T23:59:59.000Z

87

THE BRAKING INDEX OF PSR J1734-3333 AND THE MAGNETAR POPULATION  

SciTech Connect

PSR J1734-3333 is a radio pulsar rotating with a period P = 1.17 s and slowing down with a period derivative P-dot =2.28x10{sup -12}, the third largest among rotation-powered pulsars. These properties are midway between those of normal rotation-powered pulsars and magnetars, two populations of neutron stars that are notably different in their emission properties. Here we report on the measurement of the second period derivative of the rotation of PSR J1734-3333 and calculate a braking index n = 0.9 {+-} 0.2. This value is well below 3, the value expected for an electromagnetic braking due to a constant magnetic dipole, and indicates that this pulsar may soon have the rotational properties of a magnetar. While there are several mechanisms that could lead to such a low braking index, we discuss this observation, together with the properties exhibited by some other high- P-dot rotation-powered pulsars, and interpret it as evidence of a possible evolutionary route for magnetars through a radio-pulsar phase, supporting a unified description of the two classes of the object.

Espinoza, C. M.; Lyne, A. G. [Jodrell Bank Centre for Astrophysics, School of Physics and Astronomy, University of Manchester, Manchester M13 9PL (United Kingdom); Kramer, M. [MPI fuer Radioastronomie, Auf dem Huegel 69, 53121 Bonn (Germany); Manchester, R. N. [Australia Telescope National Facility, CSIRO Astronomy and Space Science, Epping, NSW 1710 (Australia); Kaspi, V. M., E-mail: cme@jb.man.ac.uk [Department of Physics, McGill University, Montreal, QC H3A 2T8 (Canada)

2011-11-01T23:59:59.000Z

88

Light front Casimir effect at finite temperature  

E-Print Network (OSTI)

The correct description of the standard Casimir effect for periodic boundary conditions via light front formalism implies in these conditions imposed at fixed Minkowski times [Almeida {\\it et al.} Phys. Rev. {\\bf D 87}, 065028 (2013); Chabysheva and Hiller, Phys. Rev. {\\bf D 88}, 085006 (2013)] instead of fixed light front times. The unphysical nature of this latter condition is manifested in the vacuum part by no regularization yielding a finite Casimir energy density [Lenz and Steinbacher, Phys. Rev. {\\bf D 67}, 045010 (2003)]. In the present paper, we extend this discussion and analyze the problem of the light front quantization with simultaneous presence of a thermal bath and boundary conditions. Considering both the oblique light front as well as Dirac light front coordinates, we show that the imposition of periodic boundary conditions at fixed Minkowski times recovers the expected behaviors for the energy density and Casimir entropy. We also investigate how the unphysical nature of the periodic boundary...

Rodrigues, P L M; Alves, Danilo T; Alves, Van Srgio; Silva, Charles R

2015-01-01T23:59:59.000Z

89

Design Principles of a flywheel Regenerative Braking System (f-RBS) for Formula SAE type racecar and system testing on a Virtual Test Rig modeled on MSC ADAMS  

E-Print Network (OSTI)

momentum in the industry [4]. These vehicles (BEVs and HEVS) use electric motor/generator pairs to propel themselves and to recapture braking energy (electric RBS) and the power source is the battery. The regenerative braking system uses a generator..., aerodynamic and road losses. 4. Improvised Transmission design to reduce losses. 5. Hybrid and Alternative Energy Propulsion systems e.g. the Hybrid Electric Vehicle (HEV), the Fuel Cell Vehicle (FCV). 6. Recycling Braking energy Storage and reuse...

Pochiraju, Anirudh

2012-08-31T23:59:59.000Z

90

Spinning disk for compressive imaging  

Science Journals Connector (OSTI)

We report the first, to the best of our knowledge, experimental implementation of a spinning-disk configuration for high-speed compressive image acquisition. A single rotating mask...

Shen, H; Gan, L; Newman, N; Dong, Y; Li, C; Huang, Y; Shen, Y C

2012-01-01T23:59:59.000Z

91

Stability of cosmological detonation fronts  

E-Print Network (OSTI)

The steady state propagation of a phase transition front is classified, according to hydrodynamics, as a deflagration or a detonation, depending on its velocity with respect to the fluid. These propagation modes are further divided into three types, namely, weak, Jouguet, and strong solutions, according to their disturbance of the fluid. However, some of these hydrodynamic modes will not be realized in a phase transition. One particular cause is the presence of instabilities. In this work we study the linear stability of weak detonations, which are generally believed to be stable. After discussing in detail the weak detonation solution, we consider small perturbations of the interface and the fluid configuration. When the balance between the driving and friction forces is taken into account, it turns out that there are actually two different kinds of weak detonations, which behave very differently as functions of the parameters. We show that the branch of stronger weak detonations are unstable, except very close to the Jouguet point, where our approach breaks down.

Ariel Megevand; Federico Agustin Membiela

2014-02-24T23:59:59.000Z

92

Existence and stability of curved multidimensional detonation fronts  

E-Print Network (OSTI)

Existence and stability of curved multidimensional detonation fronts N. Costanzino , H. K. Jenssen of curved detonation fronts 32 7.1 ZND fronts of strong detonations in the two most commonly studied inviscid models of combustion, the ZND (finite

93

Magnesium Front End Development (AMD 603/604/904) | Department...  

Energy.gov (U.S. Department of Energy (DOE)) Indexed Site

Magnesium Front End Development (AMD 603604904) Magnesium Front End Development (AMD 603604904) 2011 DOE Hydrogen and Fuel Cells Program, and Vehicle Technologies Program...

94

Application of Rarefied Gas Dynamics to the Head-Disk Interface in Hard Disk Drives  

E-Print Network (OSTI)

of a magnetic disk and a thermal flying height control (TFC)gration on the flying head slider at the head-disk interfaceThermal flying-height control sliders in hard disk drives

Liu, Nan

2010-01-01T23:59:59.000Z

95

Bay Front Biomass Facility | Open Energy Information  

Open Energy Info (EERE)

Front Biomass Facility Front Biomass Facility Jump to: navigation, search Name Bay Front Biomass Facility Facility Bay Front Sector Biomass Location Ashland County, Wisconsin Coordinates 46.9794969°, -90.4824892° Loading map... {"minzoom":false,"mappingservice":"googlemaps3","type":"ROADMAP","zoom":14,"types":["ROADMAP","SATELLITE","HYBRID","TERRAIN"],"geoservice":"google","maxzoom":false,"width":"600px","height":"350px","centre":false,"title":"","label":"","icon":"","visitedicon":"","lines":[],"polygons":[],"circles":[],"rectangles":[],"copycoords":false,"static":false,"wmsoverlay":"","layers":[],"controls":["pan","zoom","type","scale","streetview"],"zoomstyle":"DEFAULT","typestyle":"DEFAULT","autoinfowindows":false,"kml":[],"gkml":[],"fusiontables":[],"resizable":false,"tilt":0,"kmlrezoom":false,"poi":true,"imageoverlays":[],"markercluster":false,"searchmarkers":"","locations":[{"text":"","title":"","link":null,"lat":46.9794969,"lon":-90.4824892,"alt":0,"address":"","icon":"","group":"","inlineLabel":"","visitedicon":""}]}

96

Coniferous Forests of the Colorado Front Range  

Science Journals Connector (OSTI)

Forests along the Front Range of Colorado are exposed to elevated concentrations of ozone and other pollutants (see Chapter 3) due to emissions from the urbanized corridor stretching from Colorado Springs to D...

D. A. Graybill; D. L. Peterson

1992-01-01T23:59:59.000Z

97

Strings in plane-fronted gravitational waves  

E-Print Network (OSTI)

Brinkmann's plane-fronted gravitational waves with parallel rays --~shortly pp-waves~-- are shown to provide, under suitable conditions, exact string vacua at all orders of the sigma-model perturbation expansion.

C. Duval; Z. Horvath; P. A. Horvathy

2006-02-13T23:59:59.000Z

98

Reflectivity in shock wave fronts of xenon  

Science Journals Connector (OSTI)

New results for the reflection coefficient of shock-compressed dense xenon plasmas at pressures of 1.620 GPa and temperatures around 30?000 K are interpreted. Reflectivities typical of metallic systems are found at high densities. A consistent description of the measured reflectivities is achieved if a finite width of the shock wave front is considered. Several mechanisms to give a microscopic explanation for a finite extension of the shock front are discussed.

T Raitza; H Reinholz; G Rpke; V Mintsev; A Wierling

2006-01-01T23:59:59.000Z

99

Slow modes in Keplerian disks  

E-Print Network (OSTI)

Low-mass disks orbiting a massive body can support "slow" normal modes, in which the eigenfrequency is much less than the orbital frequency. Slow modes are lopsided, i.e., the azimuthal wavenumber m=1. We investigate the properties of slow modes, using softened self-gravity as a simple model for collective effects in the disk. We employ both the WKB approximation and numerical solutions of the linear eigenvalue equation. We find that all slow modes are stable. Discrete slow modes can be divided into two types, which we label g-modes and p-modes. The g-modes involve long leading and long trailing waves, have properties determined by the self-gravity of the disk, and are only present in narrow rings or in disks where the precession rate is dominated by an external potential. In contrast, the properties of p-modes are determined by the interplay of self-gravity and other collective effects. P-modes involve both long and short waves, and in the WKB approximation appear in degenerate leading/trailing pairs. Disks support a finite number---sometimes zero---of discrete slow modes, and a continuum of singular modes.

Scott Tremaine

2000-11-30T23:59:59.000Z

100

Dynamical Constraints on Disk Masses  

E-Print Network (OSTI)

While the total interior mass of a galaxy is reasonably well determined by a good rotation curve, the relative contributions from disk, bulge and halo are only weakly constrained by one-dimensional data. Barred galaxies are intrinsically more complicated, but provide much tighter constraints on the disk masses and support the idea that most of the mass in the inner parts of bright galaxies is in their stars. There appears to be no systematic difference in dark matter content between barred and unbarred galaxies, consistent with the theoretical result that the global stability of galaxies with dense centers does not depend on their halo fraction. The rotation curve shapes of lower luminosity and low-surface-brightness galaxies, on the other hand, indicate significant mass in the DM halo even near their centers. We find that most DM halos appear to have large cores, inconsistent with the predictions from cosmological simulations. We also show that such large-core halos can result from compression by disk infall of physically reasonable initial halos. Maximum disks, while apparently required by the data, do seem to present some puzzles; most notably they re-open the old disk-halo ``conspiracy'' issue and incorrectly predict that surface brightness should be a second parameter in the Tully-Fisher relation.

J. A. Sellwood

1999-03-11T23:59:59.000Z

Note: This page contains sample records for the topic "brakes front disk" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


101

Probability of failure of the waste hoist brake system at the Waste Isolation Pilot Plant (WIPP)  

SciTech Connect

In its most recent report on the annual probability of failure of the waste hoist brake system at the Waste Isolation Pilot Plant (WIPP), the annual failure rate is calculated to be 1.3E({minus}7)(1/yr), rounded off from 1.32E({minus}7). A calculation by the Environmental Evaluation Group (EEG) produces a result that is about 4% higher, namely 1.37E({minus}7)(1/yr). The difference is due to a minor error in the US Department of Energy (DOE) calculations in the Westinghouse 1996 report. WIPP`s hoist safety relies on a braking system consisting of a number of components including two crucial valves. The failure rate of the system needs to be recalculated periodically to accommodate new information on component failure, changes in maintenance and inspection schedules, occasional incidents such as a hoist traveling out-of-control, either up or down, and changes in the design of the brake system. This report examines DOE`s last two reports on the redesigned waste hoist system. In its calculations, the DOE has accepted one EEG recommendation and is using more current information about the component failures rates, the Nonelectronic Parts Reliability Data (NPRD). However, the DOE calculations fail to include the data uncertainties which are described in detail in the NPRD reports. The US Nuclear Regulatory Commission recommended that a system evaluation include mean estimates of component failure rates and take into account the potential uncertainties that exist so that an estimate can be made on the confidence level to be ascribed to the quantitative results. EEG has made this suggestion previously and the DOE has indicated why it does not accept the NRC recommendation. Hence, this EEG report illustrates the importance of including data uncertainty using a simple statistical example.

Greenfield, M.A. [Univ. of California, Los Angeles, CA (United States); Sargent, T.J. [Univ. of Chicago, IL (United States)]|[Stanford Univ., CA (United States). Hoover Institution

1998-01-01T23:59:59.000Z

102

Head/disk interface tribology in the nanometer regime  

E-Print Network (OSTI)

contact between flying slider and disk becomes increasinglythe highest amplitude was observed when flying on disk 3 andthe lowest when flying on disk 1. The amplitudes for the

Xu, Jianfeng

2008-01-01T23:59:59.000Z

103

Propagation and structure of planar streamer fronts  

Science Journals Connector (OSTI)

Streamers are a mode of dielectric breakdown of a gas in a strong electric field: A sharp nonlinear ionization wave propagates into a nonionized gas, leaving a nonequilibrium plasma behind. The ionization avalanche in the tip of the wave is due to free electrons being accelerated in the strong field and ionizing the gas by impact. This chain reaction deeper in the wave is suppressed by the generated free charges screening the field. Simulations of streamers show two widely separated spatial scales: the width of the charged layer where the electron density gradients and the ionization rate are very large [O(?m)], and the width of the electrically screened, finger-shaped, and ionized region [O(mm)]. We thus recently have suggested analyzing first the properties of the charge-ionization layer on the inner scale on which it is almost planar, and then understanding the streamer shape on the outer scale as the motion of an effective interface, as is done in other examples of nonequilibrium pattern formation. The first step thus is the analysis of the inner dynamics of planar streamer fronts. For these, we resolve the long-standing question about what determines the front speed, by applying the modern insights of pattern formation to the streamer equations used in the recent simulations. These include field-driven impact ionization, electron drift and diffusion, and the Poisson equation for the electric field. First, in appropriately chosen dimensionless units only one parameter remains to characterize the gas, the dimensionless electron diffusion constant D; for typical gases under normal conditions D?0.10.3. Then we determine essentially all relevant properties of planar streamer fronts. Technically, we identify the propagation of streamer fronts as an example of front propagation into unstable states. In terms of the marginal stability scenario we then find that the front approached asymptotically starting from any sufficiently localized initial condition (the ``selected front'') is the steepest uniformly translating front solution, which is physical and stable. Negatively charged fronts are selected by linear marginal stability, which allows us to derive their velocity analytically. Positively charged fronts can only propagate due to electron diffusion against the electric field; as a result their behavior is singular in the limit of D?0. For D?1, these fronts are selected by nonlinear marginal stability and we have to apply numerical methods for predicting the selected front velocity. For larger D, linear marginal stability applies and the velocity can be determined analytically. Numerical integrations of the temporal evolution of planar fronts out of localized initial conditions confirm all our analytical and numerical predictions for the selection. Finally, our general predictions for the selected front velocity and for the degree of ionization of the plasma are in semiquantitative agreement with recent numerical solutions of three-dimensional streamer propagation. This gives credence to our suggestion that the front analysis on the inner (?m) scale yields the moving boundary conditions for a moving ``streamer interface,'' whose pattern formation is governed by the evolution of the fields on the outer (mm) scale.

Ute Ebert, Wim van Saarloos, and Christiane Caroli

1997-02-01T23:59:59.000Z

104

Thermo-mechanical characterization of nano filled and fiber reinforced brake friction materials  

Science Journals Connector (OSTI)

Brake friction materials filled with multiwalled carbon nanotubes (MWCNT) and nanoclay have been fabricated and characterize for thermo-mechanical properties. Thermo gravimetric analysis (TGA) show that the stability of the friction composites increased with increase in MWCNT and nanoclay contents. Dynamic mechanical analysis (DMA) of the composite have been carried out to characterize the storage modulus (E?) loss modulus (E?) and damping factor (Tan ?) as a function of temperature. The storage and loss modulus show a maxima at lower content of MWCNT and nanoclay.

2013-01-01T23:59:59.000Z

105

Light-Front Holography and the Light-Front Schrodinger Equation  

SciTech Connect

One of the most important nonperturbative methods for solving QCD is quantization at fixed light-front time {tau} = t+z=c - Dirac's 'Front Form'. The eigenvalues of the light-front QCD Hamiltonian predict the hadron spectrum and the eigensolutions provide the light-front wavefunctions which describe hadron structure. More generally, we show that the valence Fock-state wavefunctions of the light-front QCD Hamiltonian satisfy a single-variable relativistic equation of motion, analogous to the nonrelativistic radial Schrodinger equation, with an effective confining potential U which systematically incorporates the effects of higher quark and gluon Fock states. We outline a method for computing the required potential from first principles in QCD. The holographic mapping of gravity in AdS space to QCD, quantized at fixed light-front time, yields the same light front Schrodinger equation; in fact, the soft-wall AdS/QCD approach provides a model for the light-front potential which is color-confining and reproduces well the light-hadron spectrum. One also derives via light-front holography a precise relation between the bound-state amplitudes in the fifth dimension of AdS space and the boost-invariant light-front wavefunctions describing the internal structure of hadrons in physical space-time. The elastic and transition form factors of the pion and the nucleons are found to be well described in this framework. The light-front AdS/QCD holographic approach thus gives a frame-independent first approximation of the color-confining dynamics, spectroscopy, and excitation spectra of relativistic light-quark bound states in QCD.

Brodsky, Stanley J.; de Teramond, Guy

2012-08-15T23:59:59.000Z

106

QCD and Light-Front Dynamics  

SciTech Connect

AdS/QCD, the correspondence between theories in a dilaton-modified five-dimensional anti-de Sitter space and confining field theories in physical space-time, provides a remarkable semiclassical model for hadron physics. Light-front holography allows hadronic amplitudes in the AdS fifth dimension to be mapped to frame-independent light-front wavefunctions of hadrons in physical space-time. The result is a single-variable light-front Schroedinger equation which determines the eigenspectrum and the light-front wavefunctions of hadrons for general spin and orbital angular momentum. The coordinate z in AdS space is uniquely identified with a Lorentz-invariant coordinate {zeta} which measures the separation of the constituents within a hadron at equal light-front time and determines the off-shell dynamics of the bound state wavefunctions as a function of the invariant mass of the constituents. The hadron eigenstates generally have components with different orbital angular momentum; e.g., the proton eigenstate in AdS/QCD with massless quarks has L = 0 and L = 1 light-front Fock components with equal probability. Higher Fock states with extra quark-anti quark pairs also arise. The soft-wall model also predicts the form of the nonperturbative effective coupling and its {beta}-function. The AdS/QCD model can be systematically improved by using its complete orthonormal solutions to diagonalize the full QCD light-front Hamiltonian or by applying the Lippmann-Schwinger method to systematically include QCD interaction terms. Some novel features of QCD are discussed, including the consequences of confinement for quark and gluon condensates. A method for computing the hadronization of quark and gluon jets at the amplitude level is outlined.

Brodsky, Stanley J.; de Teramond, Guy F.; /SLAC /Southern Denmark U., CP3-Origins /Costa Rica U.

2011-01-10T23:59:59.000Z

107

Curved detonation fronts in solid explosives 1 Curved detonation fronts in solid explosives#  

E-Print Network (OSTI)

Curved detonation fronts in solid explosives 1 Curved detonation fronts in solid explosives. Aslam and D. S. Stewart TAM Department# University of Illinois Urbana# IL 61801 USA Abstract# Detonation Shock Dynamics #DSD# can be used to model the e#ects that shock curvature # has on detonation speed D n

Aslam, Tariq

108

Curved detonation fronts in solid explosives 1 Curved detonation fronts in solid explosives  

E-Print Network (OSTI)

Curved detonation fronts in solid explosives 1 Curved detonation fronts in solid explosives. Aslam and D. S. Stewart TAM Department, University of Illinois Urbana, IL 61801 USA Abstract: Detonation Shock Dynamics (DSD) can be used to model the eects that shock curvature has on detonation speed Dn

Aslam, Tariq

109

Fault detection and diagnosis within a wind turbine mechanical braking system using condition monitoring  

Science Journals Connector (OSTI)

Renewable energy sources have a key role to play in the global energy mix as a means of reducing the impact of energy production on climate change. Wind energy is the most developed of all renewable energy technologies with more than 200GW of globally installed capacity as of 2011. Analyses of wind farm maintenance costs show that up to 40% of the outlay is related to unexpected component failures that lead to costly unscheduled amendments. Wind farm operators are constantly looking for new technological developments in condition monitoring that can contribute to the minimisation of wind turbine maintenance expenditure. Early fault detection through condition monitoring can help prevent major breakdowns as well as significantly decrease associated costs. Moreover it enables the optimisation of maintenance schedules, reduces downtime, increases asset availability and enhances safety and operational reliability. Faults in the braking system are of particularly concern since they can result in catastrophic failure of the wind turbine. The present study investigates online condition monitoring based on voltages and currents for mechanical wind turbine brake system fault diagnosis.

M. Entezami; S. Hillmansen; P. Weston; M.Ph. Papaelias

2012-01-01T23:59:59.000Z

110

Rotational evolution of the Crab pulsar in the wind braking model  

E-Print Network (OSTI)

The pulsar wind model is updated by considering the effect of particle density and pulsar death. It can describe both the short term and long term rotational evolution of pulsars consistently. It is applied to model the rotational evolution of the Crab pulsar. The pulsar is spun down by a combination of magnetic dipole radiation and particle wind. The parameters of the Crab pulsar, including magnetic field, inclination angle, and particle density are calculated. The particle density in acceleration region is about 10^3 times the Goldreich-Julian charge density. The lower braking index between glitches is due to a larger particle density. This may be glitch induced magnetospheric activities in normal pulsars. Evolution of braking index and the Crab pulsar in P-Pdot diagram are calculated. The Crab pulsar will evolve from magnetic dipole radiation dominated case towards particle wind dominated case. Considering the effect of pulsar "death", the Crab pulsar (and other normal pulsars) will not evolve to the clust...

Kou, F F

2015-01-01T23:59:59.000Z

111

2. Disks and the Buffer Cache 2-1 Part 2: Disks and Caching  

E-Print Network (OSTI)

2. Disks and the Buffer Cache 2-1 Part 2: Disks and Caching References: · Elmasri Implementierung. · Mark Gurry, Peter Corrigan: Oracle Performance Tuning, 2nd Edition (with disk). · Oracle 8i.com/] · Wikipedia (RAID systems): [http://en.wikipedia.org/wiki/Redundant Array of Independent Disks] · The PC Guide

Brass, Stefan

112

Effect of thermal pole tip protrusion and disk roughness on slider disk contacts  

Science Journals Connector (OSTI)

Ultra-high areal density for hard disk drives requires a stable head disk interface at a flying height lower than 8nm. At such a low flying height, small flying height variations may cause slider/disk contacts. Slider/disk contacts can also occur ...

Jianfeng Xu; James D. Kiely; Yiao-Tee Hsia; Frank E. Talke

2009-03-01T23:59:59.000Z

113

Detecting Accretion Disks in Active Galactic Nuclei  

Science Journals Connector (OSTI)

......black hole with an accretion disk was produced by Luminet (1979...how the BH and the accretion disk are seen by an observer who is flying near the hole. Images of the...temperature of the gas in the disk. We have extended the above......

Claudio Fanton; Massimo Calvani; Fernando de Felice; Andrej Cadez

1997-04-01T23:59:59.000Z

114

Friction forces on phase transition fronts  

SciTech Connect

In cosmological first-order phase transitions, the microscopic interaction of the phase transition fronts with non-equilibrium plasma particles manifests itself macroscopically as friction forces. In general, it is a nontrivial problem to compute these forces, and only two limits have been studied, namely, that of very slow walls and, more recently, ultra-relativistic walls which run away. In this paper we consider ultra-relativistic velocities and show that stationary solutions still exist when the parameters allow the existence of runaway walls. Hence, we discuss the necessary and sufficient conditions for the fronts to actually run away. We also propose a phenomenological model for the friction, which interpolates between the non-relativistic and ultra-relativistic values. Thus, the friction depends on two friction coefficients which can be calculated for specific models. We then study the velocity of phase transition fronts as a function of the friction parameters, the thermodynamic parameters, and the amount of supercooling.

Mgevand, Ariel, E-mail: megevand@mdp.edu.ar [IFIMAR (CONICETUNMdP), Departamento de Fsica, Facultad de Ciencias Exactas y Naturales, UNMdP, Den Funes 3350, (7600) Mar del Plata (Argentina)

2013-07-01T23:59:59.000Z

115

Use of an auditory signal in a rear-end collision warning system: effects on braking force and reaction time  

E-Print Network (OSTI)

driving game. Superimposed on the game screen was the image of a car which appeared to the driver to be ahead of him/her. The image enlarged in size, appearing to be a car applying its brakes. The participant was instructed to react as he would in a real...

Hopkins, Jennifer Susan

1995-01-01T23:59:59.000Z

116

CityCarControl : an electric vehicle drive-by-wire solution for distributed steering, braking and throttle control  

E-Print Network (OSTI)

In this paper, we propose CityCarControl, a system to manage the steering, braking, and throttle of a new class of intra-city electric vehicles. These vehicles have a focus on extreme light-weight and a small parking ...

Brown, Thomas B., M. Eng. Massachusetts Institute of Technology

2010-01-01T23:59:59.000Z

117

COLORADO FRONT RANGE SEISMICITY AND SEISMIC HAZARD  

E-Print Network (OSTI)

; Herrmann, 1981) and secondary oil recovery in western Colorado at the Rangely oil field (Gibbs et al. 1973COLORADO FRONT RANGE SEISMICITY AND SEISMIC HAZARD Anne F. Sheehan University of Colorado at Boulder, 2200 Colorado Avenue, Boulder, CO 80309 John D. Godchaux Trinity University, San Antonio, TX Noah

Sheehan, Anne F.

118

Quadratic and Cubic ReactionDiffusion Fronts*  

E-Print Network (OSTI)

's student, Herr cand. Meinecke, moved a wire loop along the test tube to mark the position in the cytoplasm of frog oocytes [9], where calcium-induced calcium release provides a mechanism akin to auto- catalysis in chemical systems. Front-like calcium waves have also been found to occur on the surface

Showalter, Kenneth

119

QCD and Light-Front Holography  

SciTech Connect

The soft-wall AdS/QCD model, modified by a positive-sign dilaton metric, leads to a remarkable one-parameter description of nonperturbative hadron dynamics. The model predicts a zero-mass pion for zero-mass quarks and a Regge spectrum of linear trajectories with the same slope in the leading orbital angular momentum L of hadrons and the radial quantum number N. Light-Front Holography maps the amplitudes which are functions of the fifth dimension variable z of anti-de Sitter space to a corresponding hadron theory quantized on the light front. The resulting Lorentz-invariant relativistic light-front wave equations are functions of an invariant impact variable {zeta} which measures the separation of the quark and gluonic constituents within the hadron at equal light-front time. The result is to a semi-classical frame-independent first approximation to the spectra and light-front wavefunctions of meson and baryon light-quark bound states, which in turn predict the behavior of the pion and nucleon form factors. The theory implements chiral symmetry in a novel way: the effects of chiral symmetry breaking increase as one goes toward large interquark separation, consistent with spectroscopic data, and the the hadron eigenstates generally have components with different orbital angular momentum; e.g., the proton eigenstate in AdS/QCD with massless quarks has L = 0 and L = 1 light-front Fock components with equal probability. The soft-wall model also predicts the form of the non-perturbative effective coupling {alpha}{sub s}{sup AdS} (Q) and its {beta}-function which agrees with the effective coupling {alpha}{sub g1} extracted from the Bjorken sum rule. The AdS/QCD model can be systematically improved by using its complete orthonormal solutions to diagonalize the full QCD light-front Hamiltonian or by applying the Lippmann-Schwinger method in order to systematically include the QCD interaction terms. A new perspective on quark and gluon condensates is also reviewed.

Brodsky, Stanley J.; /SLAC /Southern Denmark U., CP3-Origins; de Teramond, Guy F.; /Costa Rica U.; ,

2010-10-27T23:59:59.000Z

120

Accretion Disks and Eruptive Phenomena  

E-Print Network (OSTI)

This paper describes eruptive phenomena in pre-main sequence stars. The eruptions of FU Orionis stars have much in common with outbursts in other accreting systems, such as dwarf novae and some symbiotic stars. These common features are best understood as increases in the rate material flows through an accretion disk. The spectroscopic properties, decay of the light curves, and outflow phenomena suggest that these outbursts arise from thermal instabilities in the disk. Available data and estimates for recurrence times indicate that young stars can accrete much, perhaps all, of their mass in FU Ori accretion events. Future observations can test this notion and place better constraints on the importance of eruptive events in the early life of a low mass star.

Scott J. Kenyon

1999-04-05T23:59:59.000Z

Note: This page contains sample records for the topic "brakes front disk" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


121

Axisymmetric bending oscillations of stellar disks  

E-Print Network (OSTI)

Self-gravitating stellar disks with random motion support both exponentially growing and, in some cases, purely oscillatory axisymmetric bending modes, unlike their cold disk counterparts. A razor-thin disk with even a very small degree of random motion in the plane is both unstable and possesses a discrete spectrum of neutral modes, irrespective of the sharpness of the edge. Random motion normal to the disk plane has a stabilizing effect but at the same time allows bending waves to couple to the internal vibrations of the particles, which causes the formerly neutral modes to decay through Landau damping. Focusing first on instabilities, I here determine the degree of random motion normal to the plane needed to suppress global, axisymmetric, bending instabilities in a family of self-gravitating disks. As found previously, bending instabilities are suppressed only when the thickness exceeds that expected from a na\\"\\i ve local criterion when the degree of pressure support within the disk plane is comparable to, or exceeds, the support from rotation. A modest disk thickness is adequate for the bending stability of most disk galaxies, except perhaps near their centers. The discretization of the neutral spectrum in a zero-thickness disk is due to the existence of a turning point for bending waves in a warm disk, which is absent when the disk is cold. When the disk is given a finite thickness, the discrete neutral modes generally become strongly damped through wave-particle interactions. It is surprising therefore that I find some simulations of warm, stable disks can support (quasi-)neutral, large-scale, bending modes that decay very slowly, if at all.

J A Sellwood

1996-04-21T23:59:59.000Z

122

Quadratic cost functional for wave-front reconstruction  

Science Journals Connector (OSTI)

A quadratic cost functional for reconstruction of a high-resolution wave front from a coarse wave front is presented. The functional uses as data the position and the direction of the...

Legarda-Senz, Ricardo; Rivera, Mariano; Rodrguez-Vera, Ramn

2002-01-01T23:59:59.000Z

123

Gust Front Characteristics as Detected by Doppler Radar  

Science Journals Connector (OSTI)

Gust fronts produce low altitude wind shear that can be hazardous to aircraft operations, especially during takeoff and landing. Radar meteorologists have long been able to identify gust front signatures in Doppler radar data, but in order to use ...

Diana L. Klingle; David R. Smith; Marilyn M. Wolfson

1987-05-01T23:59:59.000Z

124

Thermally induced wave-front distortions in laser windows  

SciTech Connect

A simple analytical expression is given for wave-front distortions and birefringence due to heating in laser windows. (AIP)

Greninger, C.E.

1986-08-01T23:59:59.000Z

125

E-Print Network 3.0 - accretion disk contamination Sample Search...  

NLE Websites -- All DOE Office Websites (Extended Search)

+ accretion disk. Left panel: Disks of various accretion, inner... disk hole, and inclination properties. ... Source: Hillenbrand, Lynne - Astronomy Department, California...

126

E-Print Network 3.0 - accretion disk size Sample Search Results  

NLE Websites -- All DOE Office Websites (Extended Search)

+ accretion disk. Left panel: Disks of various accretion, inner... disk hole, and inclination properties. ... Source: Hillenbrand, Lynne - Astronomy Department, California...

127

Front Range Energy LLC | Open Energy Information  

Open Energy Info (EERE)

Energy LLC Energy LLC Jump to: navigation, search Logo: Front Range Energy LLC Name Front Range Energy LLC Address 31375 Great Western Dr Place Windsor, Colorado Zip 80550 Sector Biofuels Product Ethanol producer Website http://www.frontrangeenergy.co Coordinates 40.4605154°, -104.8565272° Loading map... {"minzoom":false,"mappingservice":"googlemaps3","type":"ROADMAP","zoom":14,"types":["ROADMAP","SATELLITE","HYBRID","TERRAIN"],"geoservice":"google","maxzoom":false,"width":"600px","height":"350px","centre":false,"title":"","label":"","icon":"","visitedicon":"","lines":[],"polygons":[],"circles":[],"rectangles":[],"copycoords":false,"static":false,"wmsoverlay":"","layers":[],"controls":["pan","zoom","type","scale","streetview"],"zoomstyle":"DEFAULT","typestyle":"DEFAULT","autoinfowindows":false,"kml":[],"gkml":[],"fusiontables":[],"resizable":false,"tilt":0,"kmlrezoom":false,"poi":true,"imageoverlays":[],"markercluster":false,"searchmarkers":"","locations":[{"text":"","title":"","link":null,"lat":40.4605154,"lon":-104.8565272,"alt":0,"address":"","icon":"","group":"","inlineLabel":"","visitedicon":""}]}

128

Front contact solar cell with formed emitter  

SciTech Connect

A bipolar solar cell includes a backside junction formed by an N-type silicon substrate and a P-type polysilicon emitter formed on the backside of the solar cell. An antireflection layer may be formed on a textured front surface of the silicon substrate. A negative polarity metal contact on the front side of the solar cell makes an electrical connection to the substrate, while a positive polarity metal contact on the backside of the solar cell makes an electrical connection to the polysilicon emitter. An external electrical circuit may be connected to the negative and positive metal contacts to be powered by the solar cell. The positive polarity metal contact may form an infrared reflecting layer with an underlying dielectric layer for increased solar radiation collection.

Cousins, Peter John

2014-11-04T23:59:59.000Z

129

Front contact solar cell with formed emitter  

DOE Patents (OSTI)

A bipolar solar cell includes a backside junction formed by an N-type silicon substrate and a P-type polysilicon emitter formed on the backside of the solar cell. An antireflection layer may be formed on a textured front surface of the silicon substrate. A negative polarity metal contact on the front side of the solar cell makes an electrical connection to the substrate, while a positive polarity metal contact on the backside of the solar cell makes an electrical connection to the polysilicon emitter. An external electrical circuit may be connected to the negative and positive metal contacts to be powered by the solar cell. The positive polarity metal contact may form an infrared reflecting layer with an underlying dielectric layer for increased solar radiation collection.

Cousins, Peter John (Menlo Park, CA)

2012-07-17T23:59:59.000Z

130

Sterrewacht Gas evolution in protoplanetary disks  

E-Print Network (OSTI)

Sterrewacht Leiden Gas evolution in protoplanetary disks W.F. Thi , E.F. van Dishoeck , G are surrounded by 10 ­10 M of gas+dust in disks with sizes of 100­400 AU. This material may form extrasolar planets. 3 Disks have also been imaged around Vega-like stars, but are thought to be gas­poor with "!#$ M

Zadelhoff, Gerd-Jan van

131

HEATING AND COOLING PROTOSTELLAR DISKS  

SciTech Connect

We examine heating and cooling in protostellar disks using three-dimensional radiation-MHD calculations of a patch of the Solar nebula at 1 AU, employing the shearing-box and flux-limited radiation diffusion approximations. The disk atmosphere is ionized by stellar X-rays, well coupled to magnetic fields, and sustains a turbulent accretion flow driven by magnetorotational instability, while the interior is resistive and magnetically dead. The turbulent layers are heated by absorbing the light from the central star and by dissipating the magnetic fields. They are optically thin to their own radiation and cool inefficiently. The optically thick interior in contrast is heated only weakly, by re-emission from the atmosphere. The interior is colder than a classical viscous model and isothermal. The magnetic fields support an extended atmosphere that absorbs the starlight 1.5 times higher than the hydrostatic viscous model. The disk thickness thus measures not the internal temperature, but the magnetic field strength. Fluctuations in the fields move the starlight-absorbing surface up and down. The height ranges between 13% and 24% of the radius over timescales of several orbits, with implications for infrared variability. The fields are buoyant, so the accretion heating occurs higher in the atmosphere than the stresses. The heating is localized around current sheets, caused by magnetorotational instability at lower elevations and by Parker instability at higher elevations. Gas in the sheets is heated above the stellar irradiation temperature, even though accretion is much less than irradiation power when volume averaged. The hot optically thin current sheets might be detectable through their line emission.

Hirose, S. [Institute for Research on Earth Evolution, Japan Agency for Marine-Earth Science and Technology, 3173-25 Showamachi, Kanazawa-ku, Yokohama, Kanagawa 236-0001 (Japan); Turner, N. J., E-mail: shirose@jamstec.go.jp, E-mail: neal.turner@jpl.nasa.gov [Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109 (United States)

2011-05-10T23:59:59.000Z

132

Dynamical Evolution of Disk Galaxies  

E-Print Network (OSTI)

Spiral patterns are important agents of galaxy evolution. In this review, I describe how the redistribution of angular momentum by recurrent transient spiral patterns causes the random speeds of stars to rise over time, metallicity gradients to be reduced, and drives large-scale turbulence in the disk, which could be important for galactic dynamos. I also outline a possible mechanism for the recurrence of spiral instabilities and supporting evidence from solar neighborhood kinematics. Finally, I confirm that cloud scattering alone would predict the local velocity ellipsoid to be flattened, contrary to long-held expectations.

J. A. Sellwood

2008-03-11T23:59:59.000Z

133

Author's personal copy What can the braking indices tell us about the nature of pulsars?  

E-Print Network (OSTI)

additional torques by particle outflow or accretion disk, changes in inclination angle or magnetic field's personal copy pole radiation and relativistic particle flow/wind (Dar, 1999; Allen and Horvath, 2000; Xu and Qiao, 2001; Wu et al., 2003; Contopoulos et al., 2006), the models with changing inclination angles (e

Xu, Ren-Xin

134

COBE's Galactic Bar and Disk  

E-Print Network (OSTI)

A model of the bar and old stellar disk of the Galaxy has been derived from the survey of the Diffuse Infrared Background Experiment (DIRBE) of the Cosmic Background Explorer at wavelengths of 1.25, 2.2, 3.5, and 4.9 microns. It agrees very well with the data, except in directions in which the near- infrared optical depth is high. Among the conclusions drawn from the model: The Sun is located approximately 16.5 pc above the midpoint of the Galactic plane. The disk has an outer edge four kpc from the Sun, and is warped like the HI layer. It has a central hole roughly the diameter of the inner edge of the "three-kiloparsec" molecular cloud ring, and within that hole lies a bright, strong, "early-type" bar, tilted approximately 14 degrees from the Sun-Galactic center line. The model has 47 free parameters. The model is discussed in detail and contour plots and images of the residuals presented.

H. T. Freudenreich

1997-08-04T23:59:59.000Z

135

Numerical and experimental investigations of the head/disk interface  

E-Print Network (OSTI)

The E?ects of Disk Morphology on Flying-Height Modulation:5 NM Flying Height Air Bearing Sliders in Hard Disk Drives.5 NM Flying Height Air Bearing Sliders in Hard Disk Drives.

Duwensee, Maik

2007-01-01T23:59:59.000Z

136

ROM Type Holographic Disk Using Computer Generated Hologram  

Science Journals Connector (OSTI)

Holographic ROM disk that can be made by the optical disk cutting method was studied. CGH was recorded on the master disk. The simulation showed that multiplex recoding became...

Yoshida, Shuhei; Sano, Takumi; Yamamoto, Manabu; Nakajima, Masahiro; Kobayashi, Toshihiro

137

VISCOSITY IN ACCRETION DISKS PAUL J. WIITA  

E-Print Network (OSTI)

VISCOSITY IN ACCRETION DISKS PAUL J. WIITA Department of Physics & Astronomy, Georgia State University Atlanta, Georgia, USA Abstract. Various proposals and prescriptions for the viscosity in accretion a solution to this difficult problem. 1. Introduction The nature of the viscosity within accretion disks

Wiita, Paul J.

138

A MODEL OF MAGNETIC BRAKING OF SOLAR ROTATION THAT SATISFIES OBSERVATIONAL CONSTRAINTS  

SciTech Connect

The model of magnetic braking of solar rotation considered by Charbonneau and MacGregor has been modified so that it is able to reproduce for the first time the rotational evolution of both the fastest and slowest rotators among solar-type stars in open clusters of different ages, without coming into conflict with other observational constraints, such as the time evolution of the atmospheric Li abundance in solar twins and the thinness of the solar tachocline. This new model assumes that rotation-driven turbulent diffusion, which is thought to amplify the viscosity and magnetic diffusivity in stellar radiative zones, is strongly anisotropic with the horizontal components of the transport coefficients strongly dominating over those in the vertical direction. Also taken into account is the poloidal field decay that helps to confine the width of the tachocline at the solar age. The model's properties are investigated by numerically solving the azimuthal components of the coupled momentum and magnetic induction equations in two dimensions using a finite element method.

Denissenkov, Pavel A., E-mail: pavel.denisenkov@gmail.co [Department of Physics and Astronomy, University of Victoria, P.O. Box 3055, Victoria, B.C., V8W 3P6 (Canada)

2010-08-10T23:59:59.000Z

139

Double-Disk Dark Matter  

Science Journals Connector (OSTI)

Abstract Based on observational tests of large scale structure and constraints on halo structure, dark matter is generally taken to be cold and essentially collisionless. On the other hand, given the large number of particles and forces in the visible world, a more complex dark sector could be a reasonable or even likely possibility. This hypothesis leads to testable consequences, perhaps portending the discovery of a rich hidden world neighboring our own. We consider a scenario that readily satisfies current bounds that we call Partially Interacting Dark Matter (PIDM). This scenario contains self-interacting dark matter, but it is not the dominant component. Even if PIDM contains only a fraction of the net dark matter density, comparable to the baryonic fraction, the subdominant components interactions can lead to interesting and potentially observable consequences. Our primary focus will be the special case of Double-Disk Dark Matter (DDDM), in which self-interactions allow the dark matter to lose enough energy to lead to dynamics similar to those in the baryonic sector. We explore a simple model in which DDDM can cool efficiently and form a disk within galaxies, and we evaluate some of the possible observational signatures. The most prominent signal of such a scenario could be an enhanced indirect detection signature with a distinctive spatial distribution. Even though subdominant, the enhanced density at the center of the galaxy and possibly throughout the plane of the galaxy (depending on precise alignment) can lead to large boost factors, and could even explain a signature as large as the 130 GeV Fermi line. Such scenarios also predict additional dark radiation degrees of freedom that could soon be detectable and would influence the interpretation of future data, such as that from Planck and from the Gaia satellite. We consider this to be the first step toward exploring a rich array of new possibilities for dark matter dynamics.

JiJi Fan; Andrey Katz; Lisa Randall; Matthew Reece

2013-01-01T23:59:59.000Z

140

MAGNETOHYDRODYNAMIC SIMULATION OF A DISK SUBJECTED TO LENSE-THIRRING PRECESSION  

SciTech Connect

When matter orbits around a central mass obliquely with respect to the mass's spin axis, the Lense-Thirring effect causes it to precess at a rate declining sharply with radius. Ever since the work of Bardeen and Petterson, it has been expected that when a fluid fills an orbiting disk, the orbital angular momentum at small radii should then align with the mass's spin. Nearly all previous work has studied this alignment under the assumption that a phenomenological 'viscosity' isotropically degrades fluid shears in accretion disks, even though it is now understood that internal stress in flat disks is due to anisotropic MHD turbulence. In this paper we report a pair of matched simulations, one in MHD and one in pure (non-viscous) HD in order to clarify the specific mechanisms of alignment. As in the previous work, we find that disk warps induce radial flows that mix angular momentum of different orientation; however, we also show that the speeds of these flows are generically transonic and are only very weakly influenced by internal stresses other than pressure. In particular, MHD turbulence does not act in a manner consistent with an isotropic viscosity. When MHD effects are present, the disk aligns, first at small radii and then at large; alignment is only partial in the HD case. We identify the specific angular momentum transport mechanisms causing alignment and show how MHD effects permit them to operate more efficiently. Last, we relate the speed at which an alignment front propagates outward (in the MHD case) to the rate at which Lense-Thirring torques deliver angular momentum at smaller radii.

Sorathia, Kareem A.; Krolik, Julian H. [Department of Physics and Astronomy, Johns Hopkins University, Baltimore, MD 21218 (United States); Hawley, John F. [Department of Astronomy, University of Virginia, Charlottesville, VA 22904 (United States)

2013-11-01T23:59:59.000Z

Note: This page contains sample records for the topic "brakes front disk" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


141

Progress on nanopatterned front electrodes for organic solar cells  

Science Journals Connector (OSTI)

We present our recent progress in the development of nanophotonic front electrodes for improved light management in organic solar cell. Experimental results and 3D electromagnetic...

Paetzold, Ulrich W; Smeets, Michael; Hadipour, Afshin; Cheyns, David

142

Subdiffusive fluctuations of pulled fronts with multiplicative noise  

Science Journals Connector (OSTI)

We study the propagation of a pulled front with multiplicative noise that is created by a local perturbation of an unstable state. Unlike a front propagating into a metastable state, where a separation of time scales for sufficiently large t creates a diffusive wandering of the front position about its mean, we predict that for so-called pulled fronts, the fluctuations are subdiffusive with root mean square wandering ?(t)?t1/4, not t1/2. The subdiffusive behavior is confirmed by numerical simulations: For t<~600, these yield an effective exponent slightly larger than 1/4.

Andrea Rocco, Ute Ebert, and Wim van Saarloos

2000-07-01T23:59:59.000Z

143

Magnesium Front End Design and Development | Department of Energy  

Energy.gov (U.S. Department of Energy (DOE)) Indexed Site

Design and Development Magnesium Front End Design and Development 2009 DOE Hydrogen Program and Vehicle Technologies Program Annual Merit Review and Peer Evaluation Meeting, May...

144

Magnesium Front End Development (AMD 603/604/904) | Department...  

Energy.gov (U.S. Department of Energy (DOE)) Indexed Site

Development (AMD 603604904) Magnesium Front End Development (AMD 603604904) 2012 DOE Hydrogen and Fuel Cells Program and Vehicle Technologies Program Annual Merit Review and...

145

Molecular Hydrogen Emission from Protoplanetary Disks  

E-Print Network (OSTI)

We have modeled self-consistently the density and temperature profiles of gas and dust in protoplanetary disks, taking into account irradiation from a central star. Making use of this physical structure, we have calculated the level populations of molecular hydrogen and the line emission from the disks. As a result, we can reproduce the observed strong line spectra of molecular hydrogen from protoplanetary disks, both in the ultraviolet (UV) and the near-infrared, but only if the central star has a strong UV excess radiation.

H. Nomura; T. J. Millar

2005-05-06T23:59:59.000Z

146

Light-Front Holography, Light-Front Wavefunctions, and Novel QCD Phenomena  

SciTech Connect

Light-Front Holography is one of the most remarkable features of the AdS/CFT correspondence. In spite of its present limitations it provides important physical insights into the nonperturbative regime of QCD and its transition to the perturbative domain. This novel framework allows hadronic amplitudes in a higher dimensional anti-de Sitter (AdS) space to be mapped to frame-independent light-front wavefunctions of hadrons in physical space-time. The model leads to an effective confining light-front QCD Hamiltonian and a single-variable light-front Schroedinger equation which determines the eigenspectrum and the light-front wavefunctions of hadrons for general spin and orbital angular momentum. The coordinate z in AdS space is uniquely identified with a Lorentz-invariant coordinate {zeta} which measures the separation of the constituents within a hadron at equal light-front time and determines the off-shell dynamics of the bound-state wavefunctions, and thus the fall-off as a function of the invariant mass of the constituents. The soft-wall holographic model modified by a positive-sign dilaton metric, leads to a remarkable one-parameter description of nonperturbative hadron dynamics - a semi-classical frame-independent first approximation to the spectra and light-front wavefunctions of meson and baryons. The model predicts a Regge spectrum of linear trajectories with the same slope in the leading orbital angular momentum L of hadrons and the radial quantum number n. The hadron eigensolutions projected on the free Fock basis provides the complete set of valence and non-valence light-front Fock state wavefunctions {Psi}{sub n/H} (x{sub i}, k{sub {perpendicular}i}, {lambda}{sub i}) which describe the hadron's momentum and spin distributions needed to compute the direct measures of hadron structure at the quark and gluon level, such as elastic and transition form factors, distribution amplitudes, structure functions, generalized parton distributions and transverse momentum distributions. The effective confining potential also creates quark-antiquark pairs from the amplitude q {yields} q{bar q}q. Thus in holographic QCD higher Fock states can have any number of extra q{bar q} pairs. We discuss the relevance of higher Fock-states for describing the detailed structure of space and time-like form factors. The AdS/QCD model can be systematically improved by using its complete orthonormal solutions to diagonalize the full QCD light-front Hamiltonian or by applying the Lippmann-Schwinger method in order to systematically include the QCD interaction terms. A new perspective on quark and gluon condensates is also obtained.

Brodsky, Stanley J.; /SLAC /Southern Denmark U., CP3-Origins; de Teramond, Guy F.; /Costa Rica U.

2012-02-16T23:59:59.000Z

147

Resolving Molecular Line Emission from Protoplanetary Disks: Observational Prospects for Disks Irradiated by Infalling Envelopes  

E-Print Network (OSTI)

Molecular line observations that could resolve protoplanetary disks of ~100 AU both spatially and kinematically would be a useful tool to unambiguously identify these disks and to determine their kinematical and physical characteristics. In this work we model the expected line emission from a protoplanetary disk irradiated by an infalling envelope, addressing the question of its detectability with subarcsecond resolution. We adopt a previously determined disk model structure that gives a continuum spectral energy distribution and a mm intensity spatial distribution that are consistent with observational constraints of HL Tau. An analysis of the capability of presently working and projected interferometers at mm and submm wavelengths shows that molecular transitions of moderate opacity at these wavelengths (e.g., C17O lines) are good candidates for detecting disk lines at subarcsecond resolution in the near future. We suggest that, in general, disks of typical Class I sources will be detectable.

Jose F. Gomez; Paola D'Alessio

1999-12-02T23:59:59.000Z

148

Resolving Molecular Line Emission from Protoplanetary Disks Observational Prospects for Disks Irradiated by Infalling Envelopes  

E-Print Network (OSTI)

Molecular line observations that could resolve protoplanetary disks of ~100 AU both spatially and kinematically would be a useful tool to unambiguously identify these disks and to determine their kinematical and physical characteristics. In this work we model the expected line emission from a protoplanetary disk irradiated by an infalling envelope, addressing the question of its detectability with subarcsecond resolution. We adopt a previously determined disk model structure that gives a continuum spectral energy distribution and a mm intensity spatial distribution that are consistent with observational constraints of HL Tau. An analysis of the capability of presently working and projected interferometers at mm and submm wavelengths shows that molecular transitions of moderate opacity at these wavelengths (e.g., C17O lines) are good candidates for detecting disk lines at subarcsecond resolution in the near future. We suggest that, in general, disks of typical Class I sources will be detectable.

Gomes, J F; Gomez, Jose F.; Alessio, Paola D'

1999-01-01T23:59:59.000Z

149

Carbon isotope fractionation in protoplanetary disks  

E-Print Network (OSTI)

We investigate the gas-phase and grain-surface chemistry in the inner 30 AU of a typical protoplanetary disk using a new model which calculates the gas temperature by solving the gas heating and cooling balance and which has an improved treatment of the UV radiation field. We discuss inner-disk chemistry in general, obtaining excellent agreement with recent observations which have probed the material in the inner regions of protoplanetary disks. We also apply our model to study the isotopic fractionation of carbon. Results show that the fractionation ratio, 12C/13C, of the system varies with radius and height in the disk. Different behaviour is seen in the fractionation of different species. We compare our results with 12C/13C ratios in the Solar System comets, and find a stark contrast, indicative of reprocessing.

Paul M. Woods; Karen Willacy

2008-12-01T23:59:59.000Z

150

Heat Transfer from a Rotating Disk  

Science Journals Connector (OSTI)

...August 1956 research-article Heat Transfer from a Rotating Disk E. C. Cobb...little has been published on the heat transfer. For laminar conditions theoretical...experimental investigation of the heat transfer for a range of conditions from...

1956-01-01T23:59:59.000Z

151

The Debris Disk Explorer: a balloon-borne coronagraph for observing debris disks  

E-Print Network (OSTI)

The Debris Disk Explorer (DDX) is a proposed balloon-borne investigation of debris disks around nearby stars. Debris disks are analogs of the Asteroid Belt (mainly rocky) and Kuiper Belt (mainly icy) in our Solar System. DDX will measure the size, shape, brightness, and color of tens of disks. These measurements will enable us to place the Solar System in context. By imaging debris disks around nearby stars, DDX will reveal the presence of perturbing planets via their influence on disk structure, and explore the physics and history of debris disks by characterizing the size and composition of disk dust. The DDX instrument is a 0.75-m diameter off-axis telescope and a coronagraph carried by a stratospheric balloon. DDX will take high-resolution, multi-wavelength images of the debris disks around tens of nearby stars. Two flights are planned; an overnight test flight within the United States followed by a month-long science flight launched from New Zealand. The long flight will fully explore the set of known de...

Roberts, Lewis C; Traub, Wesley; Unwin, Stephen; Trauger, John; Krist, John; Aldrich, Jack; Brugarolas, Paul; Stapelfeldt, Karl; Wyatt, Mark; Stuchlik, David; Lanzi, James

2013-01-01T23:59:59.000Z

152

Microsoft Word - chvs10.html  

NLE Websites -- All DOE Office Websites (Extended Search)

7 Chevrolet S-10 Electric 7 Chevrolet S-10 Electric VEHICLE SPECIFICATIONS PURPOSE-BUILT VEHICLE Base Vehicle: 1997 Chevrolet S-10 VIN: 1GCDE14H4V80003EX Seatbelt Positions: Three Standard Features: Heat Pump Climate Control System Auxillary Diesel Fuel Fired Heater (Only operates Below 40 F) Cruise Control Tilt Steering Wheel Front Wheel Drive Power Steering Power Brakes Anti-Lock Brakes Front Disk Brakes Regenerative Braking Drivers Side Air Bags AM/FM Stereo Radio Half-Bed Tonneau Cover BATTERY Manufacturer: Delphi Energy Type: Valve Regulated Lead Acid Number of Modules: 26 Weight of Module: 19 kg Weight of Pack(s): 575 kg Pack Locations: Underbody Nominal Module Voltage: 12 V Nominal System Voltage: 312 V Nominal Capacity (C/2): 48 Ah WEIGHTS Design Curb Weight: 4300 lbs

153

Front contact solar cell with formed electrically conducting layers on the front side and backside  

DOE Patents (OSTI)

A bipolar solar cell includes a backside junction formed by a silicon substrate and a first doped layer of a first dopant type on the backside of the solar cell. A second doped layer of a second dopant type makes an electrical connection to the substrate from the front side of the solar cell. A first metal contact of a first electrical polarity electrically connects to the first doped layer on the backside of the solar cell, and a second metal contact of a second electrical polarity electrically connects to the second doped layer on the front side of the solar cell. An external electrical circuit may be electrically connected to the first and second metal contacts to be powered by the solar cell.

Cousins, Peter John

2012-06-26T23:59:59.000Z

154

Investigation of the Brazil Current front variability from altimeter data  

E-Print Network (OSTI)

Investigation of the Brazil Current front variability from altimeter data Gustavo J. Goni Atlantic, Brazil Abstract. The southwestern Atlantic Ocean is characterized by the confluence of the Brazil in conjunction with a two-layer dynamical ocean scheme to monitor the Brazil Current front and to investigate its

155

Heuristically Driven Front Propagation for Fast Geodesic Extraction  

E-Print Network (OSTI)

Heuristically Driven Front Propagation for Fast Geodesic Extraction Gabriel Peyr´e Laurent D. Cohen to quickly extract geodesic paths on images and 3D meshes. We use a heuristic to drive the front propagation that is similar to the A algorithm used in artificial intelli- gence. In order to find very quickly geodesic paths

Paris-Sud XI, Université de

156

Existence and stability of curved multidimensional detonation fronts  

E-Print Network (OSTI)

Existence and stability of curved multidimensional detonation fronts N. Costanzino , H. K. Jenssen for ZND detonations was begun by J.J. Erpenbeck in [E1]. He used a normal mode analysis to define, multidimensional detonation fronts for ideal polytropic gases in both the ZND and Chapman-Jouguet models

Williams, Mark

157

Propagating solitary waves along a rapidly moving crack front  

Science Journals Connector (OSTI)

... Much recent research has focused on crack front coherence and roughening. Simplified models (mode III) of fracture as well as more general models of ... the cumulative effect of numerous asperities would be to cause a crack front to continually roughen. We point out that despite this possibility of increasing roughness, the propagating nature of ...

Eran Sharon; Gil Cohen; Jay Fineberg

2001-03-01T23:59:59.000Z

158

Description and Simulation of Gust Front Wind Field Lijuan Wanga  

E-Print Network (OSTI)

-stationarity of the wind field associated with these extreme events poses serious challenges in their modelingDescription and Simulation of Gust Front Wind Field Lijuan Wanga , Ahsan Kareemb a Nat front wind field is proposed based on the time-frequency description of the wind field. Traditionally

Kareem, Ahsan

159

Hadron collisions at ultrahigh energies: black disk or resonant disk modes?  

E-Print Network (OSTI)

The analysis of current ultrahigh energy data for hadronic total cross sections and diffractive scattering cross sections points to a steady growth of the optical density with energy for elastic scattering amplitudes in the impact parameter space, $b$. At LHC energy the profile function of the $pp$-scattering amplitude, $T(b)$, reaches the black disk limit at small $b$. Two scenarios are possible at larger energies, $\\sqrt{s}\\ga 100$ TeV. First, the profile function gets frozen in the black disk limit, $T(b)\\simeq 1$ while the radius of the black disk $R_{black\\;disk}$ is increasing with $\\sqrt s$, providing $\\sigma_{tot}\\sim \\ln^2s$, $\\sigma_{el}\\sim \\ln^2s$, $\\sigma_{inel}\\sim \\ln^2s$. In another scenario the profile function continues to grow at $\\sqrt{s}\\ga 100$ TeV approaching the maximal value, $T(b)\\simeq 2$, that means the resonant disk mode. We discuss features of the resonant disk mode when the disk radius, $R_{resonant\\;disk}\\,$, increases providing the growth of the total and elastic cross sections $\\sigma_{tot}\\sim \\ln^2s$, $\\sigma_{el}\\sim \\ln^2s$, but a more slow increase of inelastic cross section, $\\sigma_{inel}\\sim \\ln s$.

V. V. Anisovich; V. A. Nikonov; J. Nyiri

2014-08-11T23:59:59.000Z

160

Flame front geometry in premixed turbulent flames  

SciTech Connect

Experimental and numerical determinations of flame front curvature and orientation in premixed turbulent flames are presented. The experimental data is obtained from planar, cross sectional images of stagnation point flames at high Damkoehler number. A direct numerical simulation of a constant energy flow is combined with a zero-thickness, constant density flame model to provide the numerical results. The computational domain is a 32{sup 3} cube with periodic boundary conditions. The two-dimensional curvature distributions of the experiments and numerical simulations compare well at similar q{prime}/S{sub L} values with means close to zero and marked negative skewness. At higher turbulence levels the simulations show that the distributions become symmetric about zero. These features are also found in the three dimensional distributions of curvature. The simulations support assumptions which make it possible to determine the mean direction cosines from the experimental data. This leads to a reduction of 12% in the estimated flame surface area density in the middle of the flame brush. 18 refs.

Shepherd, I.G. (Lawrence Berkeley Lab., CA (United States)); Ashurst, W.T. (Sandia National Labs., Livermore, CA (United States))

1991-12-01T23:59:59.000Z

Note: This page contains sample records for the topic "brakes front disk" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


161

The Galactic thick and thin disks: differences in evolution  

E-Print Network (OSTI)

Recent observations demonstrate that the thin and thick disks of the Galaxy have different chemical abundance trends and evolution timescales. The relative abundances of $\\alpha$-elements in the thick Galactic disk are increased relative to the thin disk. Our goal is to investigate the cause of such differences in thick and thin disk abundances. We investigate the chemical evolution of the Galactic disk in the framework of the open two-zone model with gas inflow. The Galactic abundance trends for $\\alpha$-elements (Mg, Si, O) and Fe are predicted for the thin and thick Galactic disks. The star formation histories of the thin and thick disks must have been different and the gas infall must have been more intense during the thick disk evolution that the thin disk evolution.

T. V. Nykytyuk; T. V. Mishenina

2006-05-26T23:59:59.000Z

162

SciTech Connect: On the Front Lines of the Cold War Los Alamos...  

Office of Scientific and Technical Information (OSTI)

On the Front Lines of the Cold War Los Alamos 1970-1992 Citation Details In-Document Search Title: On the Front Lines of the Cold War Los Alamos 1970-1992 On the Front Lines of the...

163

E-Print Network 3.0 - accretion disk rim Sample Search Results  

NLE Websites -- All DOE Office Websites (Extended Search)

Summary: that the matter accreting through the disk is deflected along the magnetic field lines (of stellar andor disk... ): (A) the dust thermal emission from the disk inner...

164

E-Print Network 3.0 - accretion disk signatures Sample Search...  

NLE Websites -- All DOE Office Websites (Extended Search)

wind to disk accretion rates, the viscosity in the disk... Accretion Disk Evolution with Wind Infall II. Results of 3D Hydrodynamical Simulations... how the evolution and...

165

Universal Algebraic Relaxation of Fronts Propagating into an Unstable State and Implications for Moving Boundary Approximations  

Science Journals Connector (OSTI)

We analyze the relaxation of fronts propagating into unstable states. While pushed fronts relax exponentially like fronts propagating into a metastable state, pulled or linear marginal stability fronts relax algebraically. As a result, for thin fronts of this type, the standard moving boundary approximation fails. The leading relaxation terms for velocity and shape are of order 1/t and 1/t3/2. These universal terms are calculated exactly with a new systematic analysis that unifies various heuristic approaches to front propagation.

Ute Ebert and Wim van Saarloos

1998-02-23T23:59:59.000Z

166

Electron g-2 in Light-Front Quantization  

E-Print Network (OSTI)

Basis Light-front Quantization has been proposed as a nonperturbative framework for solving quantum field theory. We apply this approach to Quantum Electrodynamics and explicitly solve for the light-front wave function of a physical electron. Based on the resulting light-front wave function, we evaluate the electron anomalous magnetic moment. Nonperturbative mass renormalization is performed. Upon extrapolation to the infinite basis limit our numerical results agree with the Schwinger result obtained in perturbation theory to an accuracy of 0.06%.

Xingbo Zhao; Heli Honkanen; Pieter Maris; James P. Vary; Stanley J. Brodsky

2014-08-24T23:59:59.000Z

167

Muon capture for the front end of a muon collider  

SciTech Connect

We discuss the design of the muon capture front end for a {mu}{sup +}-{mu}{sup -} Collider. In the front end, a proton bunch on a target creates secondary pions that drift into a capture transport channel, decaying into muons. A sequence of rf cavities forms the resulting muon beams into strings of bunches of differing energies, aligns the bunches to (nearly) equal central energies, and initiates ionization cooling. The muons are then cooled and accelerated to high energy into a storage ring for high-energy high luminosity collisions. Our initial design is based on the somewhat similar front end of the International Design Study (IDS) neutrino factory.

Neuffer, D.; /Fermilab; Yoshikawa, C.; /MUONS Inc., Batavia

2011-03-01T23:59:59.000Z

168

Flying height calibration with bump disk  

Science Journals Connector (OSTI)

It is a big challenge to determine ultralow slider Flying Height (FH) accurately. The standard bump disk method is probably a reliable and acceptable method. The accuracy of the bump disk method on FH calibration depends on two key factors. One is the detection of the occurrence of slider??bump contact. The other is the understanding of the complicated slider??bump interaction process and the possible disturbance of the bumps on the slider flying performance. In this paper, the research work aiming to resolve these two key issues is reviewed. Key parameters that limit the accuracy of the bump disk method are discussed. Possible strategies to further improve the accuracy of the method are proposed.

Yansheng Ma; Bo Liu

2008-01-01T23:59:59.000Z

169

Vehicle System Dynamics, Vol. 26, No.4, October 1996, pp.301-320. Traction/Braking Force Distribution for Optimal Longitudinal  

E-Print Network (OSTI)

as the desired level of vehicle yaw motion, and the control system was designed to follow the yaw motion commandVehicle System Dynamics, Vol. 26, No.4, October 1996, pp.301-320. Traction/Braking Force in the past twenty years through the use of electronic devices. Four-wheel-steering (4WS) systems have been

Peng, Huei

170

Hydraulic Drivetrain and Regenerative Braking Team 13: Andrew Brown, Karan Desai, Andrew McGrath, Hurst Nuckols, Grant Wilson Adviser: Dr. Andrew Jackson  

E-Print Network (OSTI)

. The main components of the model include an electric motor, hydraulic pump, hydraulic motor and two 1 flow during regenerative braking Electric Motor: Provides rotational energy to the hydraulic drivetrain (% kinetic energy recovered) 24.73% Drivetrain Efficiency 67.02% Overall Efficiency 53.47% Current Electric

Carpick, Robert W.

171

Nanosecond cryogenic Yb:YAG disk laser  

Science Journals Connector (OSTI)

A cryogenic Yb:YAG disk laser is modernised to increase its average and peak power. The master oscillator unit of the laser is considerably modified so that the pulse duration decreases to several nanoseconds with the same pulse energy. A cryogenic disk laser head with a flow-through cooling system is developed. Based on two such laser heads, a new main amplifier is assembled according to an active multipass cell scheme. The total small-signal gain of cryogenic cascades is ~108.

E A Perevezentsev; I B Mukhin; I I Kuznetsov; O L Vadimova; O V Palashov

2014-01-01T23:59:59.000Z

172

Disk Mass from Large-scale Dynamics  

E-Print Network (OSTI)

The radial distribution of mass in a disk galaxy is strongly constrained by its rotation curve. The separate contributions from the individual stellar populations and dark matter (DM) are not easily disentangled, however, especially since there is generally no feature to indicate where the component dominating the central attraction switches from luminous to dark matter. Here I summarize three recent thesis projects at Rutgers University which all suggest that DM has a low density in the inner parts of bright galaxies, and that most of the mass therefore resides in the disk. In addition, I present some preliminary work on the Milky Way.

J A Sellwood

1997-11-27T23:59:59.000Z

173

Front End Loading (FEL) and Process Engineering Workflow  

E-Print Network (OSTI)

Project development for the oil refining industry is typically performed through a process called Front End Loading (FEL). In recent years, the Process and Industrial Division of Burns and McDonnell has performed several ...

Spangler, Ryan

2005-05-20T23:59:59.000Z

174

Quantitative Analysis of Reaction Front Geometry in Detonations  

E-Print Network (OSTI)

Quantitative Analysis of Reaction Front Geometry in Detonations F. Pintgen, and J.E. Shepherd Previous observations (Pintgen et al., 2003b, Pintgen, 2000) on the reaction zone struc- ture

Shepherd, Joe

175

Impacts of the Oyashio Temperature Front on the Regional Climate  

Science Journals Connector (OSTI)

Impacts of a sea surface temperature front (SSTF) in the northwestern Pacific Ocean on the large-scale summer atmospheric state in the region are examined with a regional atmospheric circulation model developed at the International Pacific ...

Mototaka Nakamura; Toru Miyama

2014-10-01T23:59:59.000Z

176

Global optimization of silicon photovoltaic cell front coatings  

E-Print Network (OSTI)

The front-coating (FC) of a solar cell controls its efficiency, determining admission of light into the absorbing material and potentially trapping light to enhance thin absorbers. Single-layer FC designs are well known, ...

Ghebrebrhan, Michael

177

Front Structure of Detonation and the Stability of Detonation  

Science Journals Connector (OSTI)

The physics of propagation of detonation waves is still a challenging topic in ... been found in experiments and 3D simulations of detonation physics, there are three types of detonation front structures. These a...

H. -S. Dou; Z. M. Hu; B. C. Khoo; C. Wang

2012-01-01T23:59:59.000Z

178

A portable MATLAB front-end for tiled microprocessors  

E-Print Network (OSTI)

Figure 1.3. The Role of MATLAB Front-end in Compilers forM. I. o. T. , 1996: Matlab teaching code. http://D. , 1999: Introduction to MATLAB. Prentice Hall PTR, Upper

Sung, Hyojin

2009-01-01T23:59:59.000Z

179

Carbon Emissions from Smouldering Peat in Shallow and Strong Fronts  

E-Print Network (OSTI)

A series of experiments of shallow and strong smouldering fronts in boreal peat have been conducted under laboratory conditions to study the CO and CO2 emissions. Peat samples of 100 mm by 100 mm in cross section and 50 ...

Rein, Guillermo; Cohen, Simon; Simeoni, Albert

2009-01-01T23:59:59.000Z

180

Magnesium-Intensive Front End Sub-Structure Development  

Energy.gov (U.S. Department of Energy (DOE)) Indexed Site

Project ID "LM077" USAMP AMP800 1 2013 DOE Merit Review Presentation Alan A. Luo General Motors Global Research and Development May 16, 2013 Magnesium-Intensive Front End...

Note: This page contains sample records for the topic "brakes front disk" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


181

Advanced integrated safeguards using front-end-triggering devices  

SciTech Connect

This report addresses potential uses of front-end-triggering devices for enhanced safeguards. Such systems incorporate video surveillance as well as radiation and other sensors. Also covered in the report are integration issues and analysis techniques.

Howell, J.A.; Whitty, W.J.

1995-12-01T23:59:59.000Z

182

Magnesium Front End Research And Development (AMD604) | Department...  

Energy.gov (U.S. Department of Energy (DOE)) Indexed Site

Research And Development (AMD604) Magnesium Front End Research And Development (AMD604) Presentation from the U.S. DOE Office of Vehicle Technologies "Mega" Merit Review 2008 on...

183

The Casimir effect in light-front quantization  

E-Print Network (OSTI)

We show that the standard result for the Casimir force between conducting plates at rest in an inertial frame can be computed in light-front quantization. This is not the same as light-front analyses where the plates are at "rest" in an infinite momentum frame. In that case, Lenz and Steinbacher have shown that the result does not agree with the standard result for plates at rest. The two important ingredients in the present analysis are a careful treatment of the boundary conditions, inspired by the work of Almeida et al. on oblique light-front coordinates, and computation of the ordinary energy density, rather than the light-front energy density.

Hiller, J R

2014-01-01T23:59:59.000Z

184

Town of Front Royal, Virginia (Utility Company) | Open Energy Information  

Open Energy Info (EERE)

Town of Front Royal, Virginia (Utility Company) Town of Front Royal, Virginia (Utility Company) Jump to: navigation, search Name Town of Front Royal Place Virginia Utility Id 6803 Utility Location Yes Ownership M NERC Location SERC Activity Distribution Yes References EIA Form EIA-861 Final Data File for 2010 - File1_a[1] LinkedIn Connections CrunchBase Profile No CrunchBase profile. Create one now! This article is a stub. You can help OpenEI by expanding it. Utility Rate Schedules Grid-background.png Commercial Commercial Dusk to Dawn Light poles Commercial Residential Residential Average Rates Residential: $0.0928/kWh Commercial: $0.0796/kWh References ↑ "EIA Form EIA-861 Final Data File for 2010 - File1_a" Retrieved from "http://en.openei.org/w/index.php?title=Town_of_Front_Royal,_Virginia_(Utility_Company)&oldid=411737"

185

The Casimir effect in light-front quantization  

E-Print Network (OSTI)

We show that the standard result for the Casimir force between conducting plates at rest in an inertial frame can be computed in light-front quantization. This is not the same as light-front analyses where the plates are at "rest" in an infinite momentum frame. In that case, Lenz and Steinbacher have shown that the result does not agree with the standard result for plates at rest. The two important ingredients in the present analysis are a careful treatment of the boundary conditions, inspired by the work of Almeida et al. on oblique light-front coordinates, and computation of the ordinary energy density, rather than the light-front energy density.

J. R. Hiller

2014-10-02T23:59:59.000Z

186

Observation of ionization fronts in low density foam targets  

SciTech Connect

Ionization fronts have been observed in low density chlorinated foam targets and low density foams confined in gold tubes using time resolved {ital K}-shell absorption spectroscopy. The front was driven by an intense pulse of soft x-rays produced by high power laser irradiation. The density and temperature profiles inferred from the radiographs provided detailed measurement of the conditions. The experimental data were compared to radiation hydrodynamics simulations and reasonable agreement was obtained. {copyright} {ital 1999 American Institute of Physics.}

Hoarty, D. [Imperial College of Science, Technology and Medicine, London (United Kingdom)] [Imperial College of Science, Technology and Medicine, London (United Kingdom); [Radiation Physics Department, AWE Aldermaston, Reading, Berkshire (United Kingdom); Willi, O.; Barringer, L.; Vickers, C. [Imperial College of Science, Technology and Medicine, London (United Kingdom)] [Imperial College of Science, Technology and Medicine, London (United Kingdom); Watt, R. [P24, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)] [P24, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Nazarov, W. [Chemistry Department, University of Dundee (United Kingdom)] [Chemistry Department, University of Dundee (United Kingdom)

1999-05-01T23:59:59.000Z

187

Heat Transfer from an Air-Cooled Rotating Disk  

Science Journals Connector (OSTI)

19 February 1974 research-article Heat Transfer from an Air-Cooled Rotating Disk J. M. Owen C...theoretical and experimental investigation into the heat transfer from a disk rotating close to a stator with a radial...

1974-01-01T23:59:59.000Z

188

Observation of Slider Landing Process in Hard Disk Drive  

Science Journals Connector (OSTI)

With the decrease in slider flying height, slider flying instability caused by sliderdisk interactions is becoming a big concern. Novel ... employed to further improve our understandings about sliderdisk intera...

Y. S. Ma; B. Liu

2005-10-01T23:59:59.000Z

189

An analysis of the annual probability of failure of the waste hoist brake system at the Waste Isolation Pilot Plant (WIPP)  

SciTech Connect

The Environmental Evaluation Group (EEG) previously analyzed the probability of a catastrophic accident in the waste hoist of the Waste Isolation Pilot Plant (WIPP) and published the results in Greenfield (1990; EEG-44) and Greenfield and Sargent (1993; EEG-53). The most significant safety element in the waste hoist is the hydraulic brake system, whose possible failure was identified in these studies as the most important contributor in accident scenarios. Westinghouse Electric Corporation, Waste Isolation Division has calculated the probability of an accident involving the brake system based on studies utilizing extensive fault tree analyses. This analysis conducted for the U.S. Department of Energy (DOE) used point estimates to describe the probability of failure and includes failure rates for the various components comprising the brake system. An additional controlling factor in the DOE calculations is the mode of operation of the brake system. This factor enters for the following reason. The basic failure rate per annum of any individual element is called the Event Probability (EP), and is expressed as the probability of failure per annum. The EP in turn is the product of two factors. One is the {open_quotes}reported{close_quotes} failure rate, usually expressed as the probability of failure per hour and the other is the expected number of hours that the element is in use, called the {open_quotes}mission time{close_quotes}. In many instances the {open_quotes}mission time{close_quotes} will be the number of operating hours of the brake system per annum. However since the operation of the waste hoist system includes regular {open_quotes}reoperational check{close_quotes} tests, the {open_quotes}mission time{close_quotes} for standby components is reduced in accordance with the specifics of the operational time table.

Greenfield, M.A. [Univ. of California, Los Angeles, CA (United States); Sargent, T.J.

1995-11-01T23:59:59.000Z

190

UNVEILING THE STRUCTURE OF PRE-TRANSITIONAL DISKS  

SciTech Connect

In the past few years, several disks with inner holes that are relatively empty of small dust grains have been detected and are known as transitional disks. Recently, Spitzer has identified a new class of 'pre-transitional disks' with gaps based on near-infrared photometry and mid-infrared spectra; these objects have an optically thick inner disk separated from an optically thick outer disk by an optically thin disk gap. A near-infrared spectrum provided the first confirmation of a gap in the pre-transitional disk of LkCa 15 by verifying that the near-infrared excess emission in this object was due to an optically thick inner disk. Here, we investigate the difference between the nature of the inner regions of transitional and pre-transitional disks using the same veiling-based technique to extract the near-infrared excess emission above the stellar photosphere. However, in this work we use detailed disk models to fit the excess continua as opposed to the simple blackbody fits previously used. We show that the near-infrared excess emission of the previously identified pre-transitional disks of LkCa 15 and UX Tau A in the Taurus cloud as well as the newly identified pre-transitional disk of ROX 44 in Ophiuchus can be fit with an inner disk wall located at the dust destruction radius. We also present detailed modeling of the broadband spectral energy distributions of these objects, taking into account the effect of shadowing by the inner disk on the outer disk, but considering the finite size of the star, unlike other recent treatments. The near-infrared excess continua of these three pre-transitional disks, which can be explained by optically thick inner disks, are significantly different from that of the transitional disks of GM Aur, whose near-infrared excess continuum can be reproduced by emission from sub-micron-sized optically thin dust, and DM Tau, whose near-infrared spectrum is consistent with a disk hole that is relatively free of small dust. The structure of pre-transitional disks may be a sign of young planets forming in these disks and future studies of pre-transitional disks will provide constraints to aid in theoretical modeling of planet formation.

Espaillat, C. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, MS-78, Cambridge, MA 02138 (United States); D'Alessio, P. [Centro de Radioastronomia y Astrofisica, Universidad Nacional Autonoma de Mexico, Morelia, Michoacan, Mexico 58089 (Mexico); Hernandez, J. [Centro de Investigaciones de Astronomia (CIDA), Merida, 5101-A (Venezuela, Bolivarian Republic of); Nagel, E. [Departamento de Astronomia, Universidad de Guanajuato, Guanajuato, Gto, Mexico 36240 (Mexico); Luhman, K. L. [Department of Astronomy and Astrophysics, Pennsylvania State University, University Park, PA 16802 (United States); Watson, D. M. [Department of Physics and Astronomy, University of Rochester, NY 14627-0171 (United States); Calvet, N.; McClure, M. [Department of Astronomy, University of Michigan, 830 Dennison Building, 500 Church Street, Ann Arbor, MI 48109 (United States); Muzerolle, J., E-mail: cespaillat@cfa.harvard.ed, E-mail: p.dalessio@crya.unam.m, E-mail: jesush@cida.v, E-mail: erick@astro.ugto.m, E-mail: kluhman@astro.psu.ed, E-mail: dmw@pas.rochester.ed, E-mail: ncalvet@umich.ed, E-mail: melisma@umich.ed, E-mail: muzerol@stsci.ed [Space Telescope Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States)

2010-07-01T23:59:59.000Z

191

Thickness Change in Molecularly Thin Lubricant Under Flying Head in Hard Disk Drives  

Science Journals Connector (OSTI)

In hard disk drives (HDDs), lubricants on disks are very important material to reduce head and disk wear. Thus, it is necessary to ... thickness to keep lubricant thickness constant on rotating disks. For this pu...

K. Yanagisawa; T. Watanabe; Y. Kawakubo; M. Yoshino

2010-10-01T23:59:59.000Z

192

MPEG-aware disk storage system  

E-Print Network (OSTI)

In the past decades the demand for systems that can process and deliver massive amount of storage has increased. Multimedia applications such as streaming audio and video require large amounts of data to be read from disk and processed for timely...

Ren, Qian

2000-01-01T23:59:59.000Z

193

DUST-DRIVEN WIND FROM DISK GALAXIES  

SciTech Connect

We study gaseous outflows from disk galaxies driven by radiation pressure on dust grains. We include the effect of bulge and dark matter halo and show that the existence of such an outflow implies a maximum value of disk mass-to-light ratio. We show that the terminal wind speed is proportional to the disk rotation speed in the limit of a cold gaseous outflow, and that in general there is a contribution from the gas sound speed. Using the mean opacity of dust grains and the evolution of the luminosity of a simple stellar population, we then show that the ratio of the wind terminal speed (v{sub {infinity}}) to the galaxy rotation speed (v{sub c}) ranges between 2 and 3 for a period of {approx}10 Myr after a burst of star formation, after which it rapidly decays. This result is independent of any free parameter and depends only on the luminosity of the stellar population and the relation between disk and dark matter halo parameters. We briefly discuss the possible implications of our results.

Sharma, Mahavir; Nath, Biman B. [Raman Research Institute, Sadashiva Nagar, Bangalore 560080 (India); Shchekinov, Yuri, E-mail: mahavir@rri.res.in, E-mail: biman@rri.res.in, E-mail: yus@sfedu.ru [Department of Physics, Southern Federal University, Rostov on Don 344090 (Russian Federation)

2011-08-01T23:59:59.000Z

194

Geodesic Disks and Clustering in a Simple Magdalene G. Borgelt  

E-Print Network (OSTI)

Geodesic Disks and Clustering in a Simple Polygon Magdalene G. Borgelt Marc van Kreveld Jun Luo.cs.uu.nl ISSN: 0924-3275 #12;Geodesic Disks and Clustering in a Simple Polygon Magdalene G. Borgelt European points lying in the interior of P. A geodesic disk GD(p, r) with center p and radius r is the set

Utrecht, Universiteit

195

Automated Design, Analysis, and Optimization of Turbomachinery Disks  

E-Print Network (OSTI)

Automated Design, Analysis, and Optimization of Turbomachinery Disks A thesis submitted of Cincinnati June 2008 Committee Chair: Dr. Mark G. Turner #12;#12;ABSTRACT Turbomachinery disks are used weight. Proper design and optimization of turbomachinery disks is an important topic that could yield

Cincinnati, University of

196

Computer Architecture Disk-based storage in computers  

E-Print Network (OSTI)

over any track! The read/write head! is attached to the end! of the arm and flies over! the disk198:211 Computer Architecture Topics: System I/O Buses #12;Disk-based storage in computers Memory Hierarchy registers! on-chip L1! cache (SRAM)! main memory! (DRAM)! local secondary storage! (local disks

Badrinath, B. R.

197

Dynamics simulation of MEMS device embedded hard disk drive systems  

Science Journals Connector (OSTI)

Currently, hard disk drives (HDD) use rotating disks to store digital data and magnetic recording heads are flying on the disk to read/write data. The recording heads are mounted on a slidersuspension assembly, which makes heads move from one ...

J. P. Yang; J. Chai; Y. Lu

2004-01-01T23:59:59.000Z

198

On the Solar System-Debris Disk Connecction  

E-Print Network (OSTI)

This paper emphasizes the connection between solar and extra-solar debris disks: how models and observations of the Solar System are helping us understand the debris disk phenomenon, and vice versa, how debris disks are helping us place our Solar System into context.

Amaya Moro-Martin

2007-12-14T23:59:59.000Z

199

Data Reconstruction from a Hard Disk Drive using Magnetic Force Microscopy  

E-Print Network (OSTI)

flying over the magnetization pattern written on the disk,disks be free of even microscopic particles, since the flying

Kanekal, Vasu

200

Photoevaporation of protostellar disks III. The appearance of photoevaporating disks around young intermediate mass stars  

E-Print Network (OSTI)

We present theoretical continuum emission spectra (SED's), isophotal maps and line profiles for several models of photoevaporating disks at different orientations with respect to the observer. The hydrodynamic evolution of these models has been the topic of the two previous papers of this series. We discuss in detail the numerical scheme used for these diagnostic radiation transfer calculations. Our results are qualitatively compared to observed ultracompact Hii-regions (UCHii's). Our conclusion is that the high fraction of ``unresolved'' UCHii's from the catalogues of Wood & Churchwell (1989) and Kurtz et al. (1994) cannot be explained by disks around massive stars. In particular, the observed infrared spectra of these objects indicate dust temperatures which are about one order of magnitude lower than expected. We suggest that disks around close companions to OB stars may be necessary to resolve this inconsistency. Alternatively, strong stellar winds and radiative acceleration could remove disk material from the immediate vicinity of luminous O stars, whereas for the lower luminosity sources considered here this will not occur. We also find that line profiles tracing the evaporated material originating from the disk are not influenced significantly by the existence of stellar winds over a wide range of wind velocities (400 - 1000 km/s). We compare our results to the bright IRAS source MWC349A. Many of its properties, especially its spatial appearance in high-resolution radio maps, can be well explained by a disk surrounding a UV luminous star with a high velocity stellar wind.

Olaf Kessel; Harold W. Yorke; Sabine Richling

1998-06-16T23:59:59.000Z

Note: This page contains sample records for the topic "brakes front disk" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


201

Why Disks Shine: the Transport of Angular Momentum in Hot, Thin Disks  

E-Print Network (OSTI)

I review recent work on the radial transport of angular momentum in ionized, Keplerian accretion disks. Proposed mechanisms include hydrodynamic and MHD local instabilities and long range effects mediated by wave transport. The most promising models incorporate the Velikhov-Chandrasekhar instability, caused by an instability of the magnetic field embedded in a differentially rotating disk. This has the important feature that the induced turbulent motions necessarily transport angular momentum outward. By contrast, convective modes may transport angular momentum in either direction. Combining the magnetic field instability with an $\\alpha-\\Omega$ dynamo driven by internal waves leads to a model in which the dimensionless viscosity scales as $(H/r)^{4/3}$. However, this model has a phenomenology which is quite different from the $\\alpha$ disk model. For example, an active disk implies some source of excitation for the internal waves. In binary systems with a mass ratio of order unity the most likely exciting mechanism is a parametric instability due to tidal forces. This implies that in systems where the accretion stream is intermittent, like MV Lyrae or TT Ari, epochs when the mass flow is absent or very small will be epochs in which the disk shrinks and becomes relatively inactive and dark. This model also implies that forced vertical mixing is important, even in convectively stable disks. I discuss various observational tests of this model and the focus of current theoretical work.

E. T. Vishniac

1993-09-28T23:59:59.000Z

202

Planetesimal formation around the snow line in MRI-driven turbulent protoplanetary disks  

E-Print Network (OSTI)

The formation of planetesimals in protoplanetary disks due to collisional sticking of smaller dust aggregates has to face at least two severe obstacles, namely the rapid loss of material due to radial inward drift and particle fragmentation due to destructive collisions. We present a scenario to circumvent these two hurdles. Our dust evolution model involves two main mechanisms. First, we consider a disk with a dead zone. In an almost laminar region close to the midplane, the relative velocities of the turbulent particles are comparatively small, which decreases the probability of destructive particle collisions. Second, turbulence is not the only source of violent relative particle velocities, because high radial drift speeds can also lead to boulder fragmentation. For this reason, we focus additionally on the snow line. Evaporation fronts can be associated with gas pressure maxima in which radial drift basically vanishes. This implies that particle fragmentation becomes even less likely. Our simulation results suggest that particles can overcome the fragmentation barrier. We find that boulders of several 100 m can form within only a few thousand years.

F. Brauer; Th. Henning; C. P. Dullemond

2008-06-10T23:59:59.000Z

203

Head wear reduction in future hard-disk drives  

Science Journals Connector (OSTI)

Head wear and head vibration due to head-disk contact are two main issues that must be resolved for the future high-density Hard Disk Drives (HDDs). To reduce head wear, disk lubricant, carbon overcoat films on head and disk surfaces, head flying characteristics and so on have been studied. In this paper, we first show the effects of several parameters on head wear, including lubricant types, their MW, and disk burnishing. Our recent results on the effects of humidity and temperature on head wear are also explained. We then explain our extended wear equation and estimate the head wear life with present technologies.

Youichi Kawakubo; Shinnichi Nakazawa; Shinnichi Kobatake

2008-01-01T23:59:59.000Z

204

The First Detailed Look at a Brown Dwarf Disk  

E-Print Network (OSTI)

The combination of mid-infrared and recent submm/mm measurements allows us to set up the first comprehensive spectral energy distribution (SED) of the circumstellar material around a young Brown Dwarf. Simple arguments suggest that the dust is distributed in the form of a disk. We compare basic models to explore the disk parameters. The modeling shows that a flat disk geometry fits well the observations. A flared disk explains the SED only if it has a puffed-up inner rim and an inner gap much larger than the dust sublimation radius. Similarities and differences with disks around T Tauri stars are discussed.

I. Pascucci; D. Apai; Th. Henning; C. P. Dullemond

2003-05-12T23:59:59.000Z

205

EXPONENTIAL GALAXY DISKS FROM STELLAR SCATTERING  

SciTech Connect

Stellar scattering off of orbiting or transient clumps is shown to lead to the formation of exponential profiles in both surface density and velocity dispersion in a two-dimensional non-self gravitating stellar disk with a fixed halo potential. The exponential forms for both nearly flat rotation curves and near-solid-body rotation curves. The exponential does not depend on initial conditions, spiral arms, bars, viscosity, star formation, or strong shear. After a rapid initial development, the exponential saturates to an approximately fixed scale length. The inner exponential in a two-component profile has a break radius comparable to the initial disk radius; the outer exponential is primarily scattered stars.

Elmegreen, Bruce G. [IBM Research Division, T.J. Watson Research Center, 1101 Kitchawan Road, Yorktown Heights, NY 10598 (United States)] [IBM Research Division, T.J. Watson Research Center, 1101 Kitchawan Road, Yorktown Heights, NY 10598 (United States); Struck, Curtis, E-mail: bge@watson.ibm.com, E-mail: curt@iastate.edu [Department of Physics and Astronomy, Iowa State University, Ames, IA 50011 (United States)] [Department of Physics and Astronomy, Iowa State University, Ames, IA 50011 (United States)

2013-10-01T23:59:59.000Z

206

Alfvenic Heating of Protostellar Accretion Disks  

E-Print Network (OSTI)

We investigate the effects of heating generated by damping of Alfven waves on protostellar accretion disks. Two mechanisms of damping are investigated, nonlinear and turbulent, which were previously studied in stellar winds (Jatenco-Pereira & Opher 1989a, b). For the nominal values studied, f=delta v/v_{A}=0.002 and F=varpi/Omega_{i}=0.1, where delta v, v_{A} and varpi are the amplitude, velocity and average frequency of the Alfven wave, respectively, and Omega_{i} is the ion cyclotron frequency, we find that viscous heating is more important than Alfven heating for small radii. When the radius is greater than 0.5 AU, Alfvenic heating is more important than viscous heating. Thus, even for the relatively small value of f=0.002, Alfvenic heating can be an important source of energy for ionizing protostellar disks, enabling angular momentum transport to occur by the Balbus-Hawley instability.

M. J. Vasconcelos; V. Jatenco-Pereira; R. Opher

1999-12-22T23:59:59.000Z

207

NETL's Supercomputer Addresses Energy Issues on Two Fronts | Department of  

Energy.gov (U.S. Department of Energy (DOE)) Indexed Site

NETL's Supercomputer Addresses Energy Issues on Two Fronts NETL's Supercomputer Addresses Energy Issues on Two Fronts NETL's Supercomputer Addresses Energy Issues on Two Fronts September 26, 2013 - 10:42am Addthis The visualization center for the SBEUC (Simulation Based Engineering User Center). Located at the Department’s National Energy Technology Laboratory in Morgantown, W. Va., the SBEUC will be powered by a high performance computer that will allow researchers to simulate phenomena that are difficult or impossible to probe experimentally. The results from simulations will become accessible through user centers that provide advanced visualization capabilities and foster collaboration among researchers. The SBEUC will be used for developing and deploying simulation tools required for overcoming energy technology barriers quickly and reliably.

208

Gray disks in perturbative Reggeon calculus  

Science Journals Connector (OSTI)

We discuss the connection between the opacity of a gray disk and its diffraction-dissociation cross section in the multichannel eikonal model which is formulated in such a way as to take account of continuum intermediate states of the projectile. The model is equivalent to Reggeon calculated to a finite order in the triple-Pomeron coupling and where the bare-Pomeron intercept exceeds unity.

G. A. Winbow

1977-07-15T23:59:59.000Z

209

Light-Front Holography and Non-Perturbative QCD  

SciTech Connect

The combination of Anti-de Sitter space (AdS) methods with light-front holography leads to a semi-classical first approximation to the spectrum and wavefunctions of meson and baryon light-quark bound states. Starting from the bound-state Hamiltonian equation of motion in QCD, we derive relativistic light-front wave equations in terms of an invariant impact variable {zeta} which measures the separation of the quark and gluonic constituents within the hadron at equal light-front time. These equations of motion in physical space-time are equivalent to the equations of motion which describe the propagation of spin-J modes in anti-de Sitter (AdS) space. Its eigenvalues give the hadronic spectrum, and its eigenmodes represent the probability distribution of the hadronic constituents at a given scale. Applications to the light meson and baryon spectra are presented. The predicted meson spectrum has a string-theory Regge form M{sup 2} = 4{kappa}{sup 2}(n + L + S = 2); i.e., the square of the eigenmass is linear in both L and n, where n counts the number of nodes of the wavefunction in the radial variable {zeta}. The space-like pion form factor is also well reproduced. One thus obtains a remarkable connection between the description of hadronic modes in AdS space and the Hamiltonian formulation of QCD in physical space-time quantized on the light-front at fixed light-front time {tau}. The model can be systematically improved by using its complete orthonormal solutions to diagonalize the full QCD light-front Hamiltonian or by applying the Lippmann-Schwinger method in order to systematically include the QCD interaction terms.

Brodsky, Stanley J.; /SLAC; de Teramond, Guy F.; /Costa Rica U.

2009-12-09T23:59:59.000Z

210

CO gas inside the protoplanetary disk cavity in HD 142527: disk structure from ALMA  

E-Print Network (OSTI)

Inner cavities and annular gaps in circumstellar disks are possible signposts of giant planet formation. The young star HD 142527 hosts a massive protoplanetary disk with a large cavity that extends up to 140 au from the central star, as seen in continuum images at infrared and millimeter wavelengths. Estimates of the survival of gas inside disk cavities are needed to discriminate between clearing scenarios. We present a spatially and spectrally resolved carbon monoxide isotopologue observations of the gas-rich disk HD 142527, in the J=2-1 line of 12CO, 13CO and C18O, obtained with the Atacama Large Millimeter Array (ALMA). We detect emission coming from inside the dust-depleted cavity in all three isotopologues. Based on our analysis of the gas in the dust cavity, the 12CO emission is optically thick, while 13CO and C18O emission are both optically thin. The total mass of residual gas inside the cavity is about 1.5-2 Jupiter masses. We model the gas with an axisymmetric disk model. Our best fit model shows t...

Perez, Sebastian; Mnard, F; Roman, P; van der Plas, G; Cieza, L; Pinte, C; Christiaens, V; Hales, A S

2014-01-01T23:59:59.000Z

211

Diamond Patterns in the Cellular Front of an Overdriven Detonation  

Science Journals Connector (OSTI)

A nonlinear integral-differential equation describing the cellular front of an overdriven detonation is obtained by an analysis carried out in the neighborhood of the instability threshold. The analysis reveals both an unusual mean streaming motion, resulting from the rotational part of the oscillatory flow, and pressure bursts generated by the crossover of cusps representative of Mach stems propagating on the detonation front. A numerical study of the nonlinear equation exhibits the diamond patterns observed in experiments. An overall physical understanding is provided.

P. Clavin and B. Denet

2002-01-10T23:59:59.000Z

212

Stability of negative ionization fronts: Regularization by electric screening?  

Science Journals Connector (OSTI)

We recently have proposed that a reduced interfacial model for streamer propagation is able to explain spontaneous branching. Such models require regularization. In the present paper we investigate how transversal Fourier modes of a planar ionization front are regularized by the electric screening length. For a fixed value of the electric field ahead of the front we calculate the dispersion relation numerically. These results guide the derivation of analytical asymptotes for arbitrary fields: for small wave-vector k, the growth rate s(k) grows linearly with k, for large k, it saturates at some positive plateau value. We give a physical interpretation of these results.

Manuel Arrays and Ute Ebert

2004-03-31T23:59:59.000Z

213

Mechanical front wheel drive tractors: a field performance study  

E-Print Network (OSTI)

are recognized for their f1nancial assistance. The John Deere product Eng1neering Center 1n Waterloo furnished technical assistance and the Dallas Branch of John Deere Company provided the mechanical front wheel dr1ve tractor. DICKEY-john Corporat1on supplied...-Cart was used to provide the same programmed load for each tractor. The 2WD tractor was ballasted with 25 percent of the total static tractor weight on the front wheels. Deere I Company recommend NFWO tractors be ballasted with 40 percent of the total static...

Babacz, William Adam

2012-06-07T23:59:59.000Z

214

Geodesic Remeshing Using Front Propagation Gabriel Peyre Laurent Cohen  

E-Print Network (OSTI)

Geodesic Remeshing Using Front Propagation Gabriel Peyr´e Laurent Cohen CMAP CEREMADE, UMR CNRS, we present a method for remeshing trian- gulated manifolds by using geodesic path calculations is automatically found. A geodesic Delaunay triangulation of the set of points is then created, using a Voronoi

Paris-Sud XI, Université de

215

FRONT CURVATURE RATE STICK MEASUREMENTS AND DETONATION SHOCK DYNAMICS CALIBRATION  

E-Print Network (OSTI)

FRONT CURVATURE RATE STICK MEASUREMENTS AND DETONATION SHOCK DYNAMICS CALIBRATION FOR PBX 9502 OVER 87545 Detonation velocities and wave shapes were measured for PBX 9502 (95 wt.% TATB, 5 wt.% Kel­F 800 and diameter effect data. For each T 0 , the simplest detonation shock dynamics model assumes that the local

Aslam, Tariq

216

FRONT CURVATURE RATE STICK MEASUREMENTS AND DETONATION SHOCK DYNAMICS CALIBRATION  

E-Print Network (OSTI)

FRONT CURVATURE RATE STICK MEASUREMENTS AND DETONATION SHOCK DYNAMICS CALIBRATION FOR PBX 9502 OVER 87545 Detonation velocities and wave shapes were measured for PBX 9502 95 wt. TATB, 5 wt. Kel-F 800 rate and diameter e ect data. For each T0, the simplest detonation shock dynamics model assumes that the local

Aslam, Tariq

217

Neutrino factory front-end: muon capture and cooling optimization  

E-Print Network (OSTI)

The neutrino factory is one of the designs proposed for a future intense neutrino beam facility. The layout discussed here focuses on the front-end of the current baseline. The challenges inherent to the cooling of muons are shown together with possible baseline optimization.

Prior, G

2010-01-01T23:59:59.000Z

218

On the propagation of a coupled saturation and pressure front  

SciTech Connect

Using an asymptotic technique, valid for a medium with smoothly varying heterogeneity, I derive an expression for the velocity of a propagating, coupled saturation and pressure front. Due to the nonlinearity of the governing equations, the velocity of the propagating front depends upon the magnitude of the saturation and pressure changes across the front in addition to the properties of the medium. Thus, the expression must be evaluated in conjunction with numerical reservoir simulation. The propagation of the two-phase front is governed by the background saturation distribution, the saturation-dependent component of the fluid mobility, the porosity, the permeability, the capillary pressure function, the medium compressibility, and the ratio of the slopes of the relative permeability curves. Numerical simulation of water injection into a porous layer saturated with a nonaqueous phase liquid indicates that two modes of propagation are important. The fastest mode of propagation is a pressure-dominated disturbance that travels through the saturated layer. This is followed, much later, by a coupled mode with a large saturation change. These two modes are also observed in a simulation using a heterogeneous porous layer. A comparison between the propagation times estimated from the results of the numerical simulation and predictions from the asymptotic expression indicates overall agreement.

Vasco, D. W.

2010-12-01T23:59:59.000Z

219

Multimaterial Front Tracking Fang Da, Christopher Batty, and Eitan Grinspun  

E-Print Network (OSTI)

.8 [Simulation and Modeling]: Types of Simulation--Animation Additional Key Words and Phrases: front tracking. Numerous additional physical and mathemat- ical applications have this same form: soap bubbles and dry the space of possible entangled mesh configurations that can arise, and topological transformations

220

Muon Front End for a Neutrino Factory and Muon Collider  

E-Print Network (OSTI)

Muon Front End for a Neutrino Factory and Muon Collider Chris Rogers, ASTeC, Rutherford Appleton Laboratory 15th January 2013 #12;High Energy Muon Facilities Growing interest in large, high energy muon facilities Neutrino Factory -> neutrino oscillations and Muon Collider -> energy frontier or Higgs factory

McDonald, Kirk

Note: This page contains sample records for the topic "brakes front disk" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


221

A FRONT TRACKING METHOD FOR TRANSITIONAL SHOCK WAVES  

E-Print Network (OSTI)

A FRONT TRACKING METHOD FOR TRANSITIONAL SHOCK WAVES HYUN­CHEOL HWANG Abstract. Non of transitional shock waves, which are dependent on the parabolic regularization of the conservation laws transitional shock waves correctly. The algorithm includes the computation of saddle­to­saddle connec­ tions

New York at Stoney Brook, State University of

222

Utility theory front to back inferring utility from agents' choices  

E-Print Network (OSTI)

Utility theory front to back ­ inferring utility from agents' choices A. M. G. Cox Dept to utility theory and consumption & investment problems. Instead of specifying an agent's utility function) and ask if it is possible to derive a utility function for which the observed behaviour is optimal. We

223

Front End Target Options K.T. McDonald  

E-Print Network (OSTI)

Front End ­ Target Options K.T. McDonald Princeton University (January 7, 2014) #12;Target System://puhep1.princeton.edu/~mcdonald/examples/accel/neuffer_ieeetns_28_2034_81.pdf Fernow et al. reviewed options in 1995: Li lenses, plasma lenses, toroidal horns, and solenoidal capture., http://puhep1

McDonald, Kirk

224

Composite polymer: Glass edge cladding for laser disks  

DOE Patents (OSTI)

Large neodymium glass laser disks for disk amplifiers such as those used in the Nova laser require an edge cladding which absorbs at 1 micrometer. This cladding prevents edge reflections from causing parasitic oscillations which would otherwise deplete the gain. Nova now utilizes volume-absorbing monolithic-glass claddings which are fused at high temperature to the disks. These perform quite well but are expensive to produce. Absorbing glass strips are adhesively bonded to the edges of polygonal disks using a bonding agent whose index of refraction matches that of both the laser and absorbing glass. Optical finishing occurs after the strips are attached. Laser disks constructed with such claddings have shown identical gain performance to the previous Nova disks and have been tested for hundreds of shots without significant degradation. 18 figs.

Powell, H.T.; Wolfe, C.A.; Campbell, J.H.; Murray, J.E.; Riley, M.O.; Lyon, R.E.; Jessop, E.S.

1987-11-02T23:59:59.000Z

225

Composite polymer-glass edge cladding for laser disks  

DOE Patents (OSTI)

Large neodymium glass laser disks for disk amplifiers such as those used in the Nova laser require an edge cladding which absorbs at 1 micrometer. This cladding prevents edge reflections from causing parasitic oscillations which would otherwise deplete the gain. Nova now utilizes volume-absorbing monolithic-glass claddings which are fused at high temperature to the disks. These perform quite well but are expensive to produce. Absorbing glass strips are adhesively bonded to the edges of polygonal disks using a bonding agent whose index of refraction matches that of both the laser and absorbing glass. Optical finishing occurs after the strips are attached. Laser disks constructed with such claddings have shown identical gain performance to the previous Nova disks and have been tested for hundreds of shots without significant degradation.

Powell, Howard T. (Livermore, CA); Riley, Michael O. (San Ramon, CA); Wolfe, Charles R. (Palo Alto, CA); Lyon, Richard E. (Livermore, CA); Campbell, John H. (Livermore, CA); Jessop, Edward S. (Tracy, CA); Murray, James E. (Livermore, CA)

1989-01-01T23:59:59.000Z

226

MOLECULAR DISK PROPERTIES IN EARLY-TYPE GALAXIES  

SciTech Connect

We study the simulated CO emission from elliptical galaxies formed in the mergers of gas-rich disk galaxies. The cold gas not consumed in the merger-driven starburst quickly resettles into a disk-like configuration. By analyzing a variety of arbitrary merger orbits that produce a range of fast- to slow-rotating remnants, we find that molecular disk formation is a fairly common consequence of gas-rich galaxy mergers. Hence, if a molecular disk is observed in an early-type merger remnant, it is likely the result of a 'wet merger' rather than a 'dry merger'. We compare the physical properties from our simulated disks (e.g., size and mass) and find reasonably good agreement with recent observations. Finally, we discuss the detectability of these disks as an aid to future observations.

Xu, X.; Walker, C. [Steward Observatory, University of Arizona, 933 N. Cherry Ave., Tucson, AZ 85721 (United States); Narayanan, D., E-mail: xxu@as.arizona.ed [Harvard-Smithsonian Center for Astrophysics, 60 Garden St. MS 51, Cambridge, MA 02138 (United States)

2010-10-01T23:59:59.000Z

227

Study of ring and ring-disk electrodes  

SciTech Connect

Rotating ring and ring-disk electrodes were modeled. The primary, secondary, and below-the-limiting current distributions for ring electrodes were computed. The ring-disk system was modeled for secondary and below-the-limiting current distributions. Mass transfer measurements in laminar, transition, and turbulent flows were made for thin rotating rings. The effect of cell walls on the potential distribution of disk electrodes was computed.

Pierini, P.E.

1981-05-01T23:59:59.000Z

228

High average power scaleable thin-disk laser  

DOE Patents (OSTI)

Using a thin disk laser gain element with an undoped cap layer enables the scaling of lasers to extremely high average output power values. Ordinarily, the power scaling of such thin disk lasers is limited by the deleterious effects of amplified spontaneous emission. By using an undoped cap layer diffusion bonded to the thin disk, the onset of amplified spontaneous emission does not occur as readily as if no cap layer is used, and much larger transverse thin disks can be effectively used as laser gain elements. This invention can be used as a high average power laser for material processing applications as well as for weapon and air defense applications.

Beach, Raymond J. (Livermore, CA); Honea, Eric C. (Sunol, CA); Bibeau, Camille (Dublin, CA); Payne, Stephen A. (Castro Valley, CA); Powell, Howard (Livermore, CA); Krupke, William F. (Pleasanton, CA); Sutton, Steven B. (Manteca, CA)

2002-01-01T23:59:59.000Z

229

Computer disk with personal information of Department of Energy...  

NLE Websites -- All DOE Office Websites (Extended Search)

Computer disk with personal information of Department of Energy's Idaho site employees lost in transit The Department of Energy's Office of Health, Safety and Security has been...

230

TIDAL DISRUPTION FLARES: THE ACCRETION DISK PHASE  

SciTech Connect

The evolution of an accretion disk, formed as a consequence of the disruption of a star by a black hole, is followed by solving numerically hydrodynamic equations. The present investigation aims to study the dependence of resulting light curves on dynamical and physical properties of such a transient disk during its existence. One of the main results derived from our simulations is that blackbody fits of X-ray data tend to overestimate the true mean disk temperature. In fact, the temperature derived from blackbody fits should be identified with the color X-ray temperature rather than the average value derived from the true temperature distribution along the disk. The time interval between the beginning of the circularization of the bound debris and the beginning of the accretion process by the black hole is determined by the viscous (or accretion) timescale, which also fixes the rising part of the resulting light curve. The luminosity peak coincides with the beginning of matter accretion by the black hole and the late evolution of the light curve depends on the evolution of the debris fallback rate. Peak bolometric luminosities are in the range 10{sup 45}-10{sup 46} erg s{sup -1}, whereas peak luminosities in soft X-rays (0.2-2.0 keV) are typically one order of magnitude lower. The typical timescale derived from our preferred models for the flare luminosity to decay by two orders of magnitude is about 3-4 yr. Predicted soft X-ray light curves reproduce quite well data on galaxies in which a variable X-ray emission possibly related to a tidal event was detected. In the cases of NGC 3599 and IC 3599, data are reproduced well by models defined by a black hole with mass {approx}10{sup 7} M{sub sun} and a disrupted star of about 1 solar mass. The X-ray variation observed in XMMSL1 is consistent with a model defined by a black hole with mass {approx}3 x 10{sup 6} M{sub sun} and a disrupted star of 1 solar mass, while that observed in the galaxy situated in the cluster A1689 is consistent with a model including a black hole of {approx}10{sup 7} M{sub sun} and a disrupted star of {approx}0.5 M{sub sun}.

Montesinos Armijo, Matias; De Freitas Pacheco, Jose A. [Observatoire de la Cote d'Azur, Laboratoire Cassiopee, Universite de Nice Sophia-Antipolis Bd de l'Observatoire, BP 4229, 06304 Nice Cedex 4 (France)

2011-08-01T23:59:59.000Z

231

ICE LINES IN CIRCUMBINARY PROTOPLANETARY DISKS  

SciTech Connect

I examine the position of the ice line in circumbinary disks heated by steady mass accretion and stellar irradiation and compare with the critical semimajor axis, interior to which planetary orbits are unstable. There is a critical binary separation, dependent on the binary parameters and disk properties, for which binaries with separations larger than this critical value have ice lines that lie interior to the boundary of stability. For an equal-mass binary comprised of 1 M{sub Sun} components, this critical separation is Almost-Equal-To 1.04 AU, and scales weakly with mass accretion rate and Rosseland mean opacity ({proportional_to}[ M-dot {kappa}{sub R}]{sup 2/9}). Assuming a steady mass accretion rate of M-dot {approx}10{sup -8} M{sub Sun} yr{sup -1} and a Rosseland mean opacity of {kappa}{sub R} {approx} 1 cm{sup 2} g{sup -1}, I show that {approx}> 80% of all binary systems with component masses M{sub *} {approx}< 2.0 M{sub Sun} have ice lines that lie interior to the critical semimajor axis. This suggests that rocky planets should not form in these systems, a prediction which can be tested by looking for planets around binaries with separations larger than the critical separation with Kepler (difficult) and with microlensing.

Clanton, Christian, E-mail: clanton@astronomy.ohio-state.edu [Department of Astronomy, Ohio State University, 140 W. 18th Ave., Columbus, OH 43210 (United States)

2013-05-01T23:59:59.000Z

232

Fisher Waves and Front Roughening in a Two-Species Invasion Model with Preemptive Competition  

E-Print Network (OSTI)

Fisher Waves and Front Roughening in a Two-Species Invasion Model with Preemptive Competition L. O study roughening of the front, using the framework of non-equilibrium interface growth. Our analysis indicates that initially flat, linear invading fronts exhibit Kardar-Parisi-Zhang (KPZ) roughening in one

Caraco, Thomas

233

Licensing Uncertain Patents: Per-Unit Royalty vs. Up-Front Fee  

E-Print Network (OSTI)

Licensing Uncertain Patents: Per-Unit Royalty vs. Up-Front Fee David Encaouay and Yassine Lefouiliz schemes are investigated: the per-unit royalty rate and the up-front fee. We provide conditions under-unit royalty scheme, the opportunity to do so does not exist under the up-front fee scheme. We also establish

Boyer, Edmond

234

Detecting research fronts in OLED field using bibliographic coupling with sliding window  

Science Journals Connector (OSTI)

Research fronts represent cutting edge studies in specific fields. One can better understand current and future development trends in the relevant field when updated with trends in research fronts. This study uses bibliographic coupling and sliding window ... Keywords: Bibliographic coupling, Citation windows, OLED, Research fronts, Sliding window

Mu-Hsuan Huang; Chia-Pin Chang

2014-03-01T23:59:59.000Z

235

Introduction Idealized Moist Jet/Front Waves Ray Tracing Momentum Flux/Forcing Conclusion Gravity Waves  

E-Print Network (OSTI)

Introduction Idealized Moist Jet/Front Waves Ray Tracing Momentum Flux/Forcing Conclusion Gravity Waves in Moist Baroclinic Jet-Front Systems Junhong Wei, Fuqing Zhang Department of Meteorology The Pennsylvania State University Tuesday 19th August, 2014 #12;Introduction Idealized Moist Jet/Front Waves Ray

Thompson, Anne

236

Adaptive Path Planning for Tracking Ocean Fronts with an Autonomous Underwater Vehicle  

E-Print Network (OSTI)

Adaptive Path Planning for Tracking Ocean Fronts with an Autonomous Underwater Vehicle Ryan N an ocean front for ecological purposes. At the high level, we envision the scenario shown in Fig. 1 front with an Autonomous Under- water Vehicle (AUV) based on predictions and/or pri- ors provided

Smith, Ryan N.

237

Nano-scale positioning, control and motion planning in hard disk drives  

E-Print Network (OSTI)

Dynamic flying height adjustment in hard disk drives throughprocessing for flying height control in hard disk drives . .for sub-3- nm flying height head-disk systems. Journal of

Boettcher, Uwe

2011-01-01T23:59:59.000Z

238

Dynamics and Stability of Thermal Flying-height Control Sliders in Hard Disk Drives  

E-Print Network (OSTI)

in ultra-low flying head-disk interfaces," Tribologyinto the gap between the flying head and disk, and they candifferent ways when flying over disks of different roughness

Zheng, Jinglin

2012-01-01T23:59:59.000Z

239

Properties of carbon overcoats and perfluoro-polyether lubricants in hard disk drives  

E-Print Network (OSTI)

stable head-disk interface at ultralow flying height," IEEElow flying sliders during contact with a lubricated disk,"for stable flying of the slider over the disk [16], [17].

Brunner, Ralf

2009-01-01T23:59:59.000Z

240

Numerical Investigation of Operational Shocks and Vibrations in Mobile Hard Disk Drives  

E-Print Network (OSTI)

Suspension Load Disk RPM Nominal Flying Height Pitch Rollwrite head and the disk is known as flying height of thefor a slider flying on top of the disk will be a negative

Rai, Rahul

2011-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "brakes front disk" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


241

Effects of diffusion on lubricant distribution under flying headon thin-film disks  

Science Journals Connector (OSTI)

Lubricants on thin-film disks have large effects on headdisk interface characteristics. They reduce head and disk wear while thick lubricant film increases friction ... in many cases. Lubricant depletion due to

K. Yanagisawa; Y. Kawakubo; M. Yoshino

2005-01-01T23:59:59.000Z

242

E-Print Network 3.0 - accretion disk properties Sample Search...  

NLE Websites -- All DOE Office Websites (Extended Search)

23 CONSTRAINTS ON ACCRETION DISK LIFETIMES Summary: accretion, inner disk hole, and inclination properties. Compared to the non-accreting no-hole pole-on disk... of various...

243

E-Print Network 3.0 - astrophysical disk models Sample Search...  

NLE Websites -- All DOE Office Websites (Extended Search)

accretion disk models. The Astrophysical... disk material to the outer disk is the X-wind model (Shu et al. 1996). The notion that young stars... of material transported to...

244

Front-end utility rate updates | OpenEI Community  

Open Energy Info (EERE)

Front-end utility rate updates Front-end utility rate updates Home > Groups > Utility Rate Rmckeel's picture Submitted by Rmckeel(297) Contributor 13 February, 2013 - 14:28 Utility Rates A few utility rate updates worth noting. We used to have a limit of 100 for results returned on the utility gateway. That has been increased, along with a few UI updates. There is now a 15em height window (sorry if that's too technical) to browse results, so all the hundreds of results don't extend the page. For the naming page however, perhaps the long list is preferred? I'm willing to tweak these heights, as well as have separate heights if it is requested for the public view and the editor view. Improvement to have results show within the block instead of outside of. Minor increase in results width on editor page.

245

Epidemic fronts in complex networks with metapopulation structure  

E-Print Network (OSTI)

Infection dynamics have been studied extensively on complex networks, yielding insight into the effects of heterogeneity in contact patterns on disease spread. Somewhat separately, metapopulations have provided a paradigm for modeling systems with spatially extended and "patchy" organization. In this paper we expand on the use of multitype networks for combining these paradigms, such that simple contagion models can include complexity in the agent interactions and multiscale structure. We first present a generalization of the Volz-Miller mean-field approximation for Susceptible-Infected-Recovered (SIR) dynamics on multitype networks. We then use this technique to study the special case of epidemic fronts propagating on a one-dimensional lattice of interconnected networks - representing a simple chain of coupled population centers - as a necessary first step in understanding how macro-scale disease spread depends on micro-scale topology. Using the formalism of front propagation into unstable states, we derive ...

Hindes, Jason; Myers, Christopher R; Schneider, David J

2013-01-01T23:59:59.000Z

246

Towards the Light Front Variables for High Energy Production Processes  

E-Print Network (OSTI)

Scale invariant presentation of inclusive spectra in terms of light front variables is proposed. The variables introduced go over to the well-known scaling variables x_F = 2p_z/sqrt(s) and x_T=2p_T/sqrt{s} in the high p_z and high p_T limits respectively. So Some surface is found in the phase space of produced pi-mesons in the inclusive reaction anti p p -> pi+- X at 22.4 GeV/c, which separates two groups of particles with significantly different characteristics. In one of these regions a naive statistical model seems to be in a good agreement with data, whereas it fails in the second region. Key words: Light front, inclusive, hadron-hadron, electron-positron, relativistic heavy ions, deep inelastic.

N. S. Amaglobeli; S. M. Esakia; V. R. Garsevanishvili; G. O. Kuratashvili; N. K. Kutsidi; R. A. Kvatadze; Yu V. Tevzadze; T. P. Topuria

1997-03-21T23:59:59.000Z

247

Towards the Light Front Variables for High Energy Production Processes  

E-Print Network (OSTI)

Scale invariant presentation of inclusive spectra in terms of light front variables is proposed. The variables introduced go over to the well-known scaling variables x_F = 2p_z/sqrt(s) and x_T=2p_T/sqrt{s} in the high p_z and high p_T limits respectively. So Some surface is found in the phase space of produced pi-mesons in the inclusive reaction anti p p -> pi+- X at 22.4 GeV/c, which separates two groups of particles with significantly different characteristics. In one of these regions a naive statistical model seems to be in a good agreement with data, whereas it fails in the second region. Key words: Light front, inclusive, hadron-hadron, electron-positron, relativistic heavy ions, deep inelastic.

Amaglobeli, N S; Garsevanishvili, V R; Kuratashvili, G O; Kutsidi, N K; Kvatadze, R A; Tevzadze, Yu V; Topuria, T P; Tevzadze, Yu V.

1998-01-01T23:59:59.000Z

248

CAPTURE OF PLANETESIMALS BY GAS DRAG FROM CIRCUMPLANETARY DISKS  

SciTech Connect

Growing giant planets have circumplanetary disks around them in the late stage of their formation if their mass is sufficiently large. We examine capture of relatively large planetesimals that are decoupled from the gas inflow, due to gas drag from a circumplanetary disk of a growing giant planet. Assuming that the structure of the circumplanetary disk is axisymmetric, and solving the three-body problem including gas drag, we perform analytic and numerical calculations for capture of planetesimals. When planetesimal random velocity is small, planetesimals approaching in the retrograde direction are more easily captured, owing to their larger velocity relative to the gas. Planetesimals with large orbital inclinations interact with the disk for a short period of time and show lower capture rates. The effect of ablation on capture rates seems insignificant, although mass loss due to ablation would be significant in the case of high random velocity. We also examine the effect of non-uniform radial distribution of planetesimals in the protoplanetary disk due to gap opening by the planet. When the random velocity of planetesimals is small, the planetesimal capture rate decreases rapidly as the half width of the gap in the planetesimal disk increases from two planetary Hill radii to three planetary Hill radii; planetesimals with low random velocities cannot approach the planet in the case of a sufficiently wide gap. Our results show that the radial distribution and random velocity of planetesimals in the protoplanetary disk are essentially important for the understanding of capture of planetesimals by circumplanetary disks.

Fujita, Tetsuya; Ohtsuki, Keiji; Suetsugu, Ryo [Department of Earth and Planetary Sciences, Kobe University, Kobe 657-8501 (Japan); Tanigawa, Takayuki [Institute of Low Temperature Science, Hokkaido University, Sapporo 060-0819 (Japan)

2013-12-01T23:59:59.000Z

249

A Normal Stellar Disk in the Galaxy Malin 1  

E-Print Network (OSTI)

Since its discovery, Malin 1 has been considered the prototype and most extreme example of the class of giant low surface brightness disk galaxies. Examination of an archival Hubble Space Telescope I-band image reveals that Malin 1 contains a normal stellar disk that was not previously recognized, having a central I-band surface brightness of mu_0 = 20.1 mag arcsec^-2 and a scale length of 4.8 kpc. Out to a radius of ~10 kpc, the structure of Malin 1 is that of a typical SB0/a galaxy. The remarkably extended, faint outer structure detected out to r~100 kpc appears to be a photometrically distinct component and not a simple extension of the inner disk. In terms of its disk scale length and central surface brightness, Malin 1 was originally found to be a very remote outlier relative to all other known disk galaxies. The presence of a disk of normal size and surface brightness in Malin 1 suggests that such extreme outliers in disk properties probably do not exist, but underscores the importance of the extended outer disk regions for a full understanding of the structure and formation of spiral galaxies.

A. J. Barth

2006-12-31T23:59:59.000Z

250

Managing hard-disk PCs in the introductory laboratory  

Science Journals Connector (OSTI)

A method is described for managing stand-alone hard-disk PCs, in an environment in which students are allowed to explore the hard disk. The system, application, and student-created files are safeguarded by management software which helps eliminate "accidental" ...

David K. Walker; David S. Tucker

1991-11-01T23:59:59.000Z

251

The gas temperature in circumstellar disks: effects of dust settling  

E-Print Network (OSTI)

The gas temperature in circumstellar disks: effects of dust settling F. Faas, G.J. van Zadelhoff, E distributions. The disk gas-temperature (T ¢¡¢£ ) is in general assumed to be equal to the dust-temperature (T¤¦¥ £ § ), due to collisions. Dust settling depends on both the gas and dust temperature. T

Zadelhoff, Gerd-Jan van

252

The Main Injector Beam Position Monitor Front-End Software  

SciTech Connect

The front-end software developed for the Main Injector (MI) BPM upgrade is described. The software is responsible for controlling a VME crate, equipped with a Motorola PowerPC board running the VxWorks operating system, a custom made timing board and up to 10 commercial digitizer boards. The complete MI BPM system is composed of 7 independent units, each collecting data from 19 to 38 BPM pickups. The MI BPM system uses several components already employed on the successful upgrade of another Fermilab machine, the Tevatron. The front-end software framework developed for the Tevatron BPM upgrade is the base for building the MI front-end software. The framework is implemented in C++ as a generic component library (GBPM) that provides an event-driven data acquisition environment. Functionality of GBPM is extended to meet MI BPM requirements, such as the ability to handle and manage data from multiple cycles; perform readout of the digitizer boards without disrupting or missing subsequent cycles; transition between closed orbit and turn-by-turn modes within a cycle, using different filter and timing configurations; and allow the definition of new cycles during normal operation.

Piccoli, Luciano; Foulkes, Stephen; Votava, Margaret; Briegel, Charles; /Fermilab

2006-05-01T23:59:59.000Z

253

Moving boundary approximation for curved streamer ionization fronts: Solvability analysis  

Science Journals Connector (OSTI)

The minimal density model for negative streamer ionization fronts is investigated. An earlier moving boundary approximation for this model consisted of a kinetic undercooling type boundary condition in a Laplacian growth problem of Hele-Shaw type. Here we derive a curvature correction to the moving boundary approximation that resembles surface tension. The calculation is based on solvability analysis with unconventional features, namely, there are three relevant zero modes of the adjoint operator, one of them diverging; furthermore, the inner-outer matching ahead of the front must be performed on a line rather than on an extended region; and the whole calculation can be performed analytically. The analysis reveals a relation between the fields ahead and behind a slowly evolving curved front, the curvature and the generated conductivity. This relation forces us to give up the ideal conductivity approximation, and we suggest to replace it by a charge neutrality approximation. This implies that the electric potential in the streamer interior is no longer constant but solves a Laplace equation; this leads to a Muskat-type problem.

Fabian Brau, Benny Davidovitch, and Ute Ebert

2008-11-21T23:59:59.000Z

254

An Eccentric Disk Model for the Nucleus of M31  

E-Print Network (OSTI)

The nucleus of M31 may be a thick eccentric disk, composed of stars traveling on nearly Keplerian orbits around a black hole or other dark compact object. This hypothesis reproduces most of the features seen in HST photometry of the center of M31; in particular the bright off-center source P1 is the apoapsis of the disk. An eccentric disk can also explain the rotation curve and asymmetric dispersion profile revealed by ground-based observations. The central object must be smaller than 1 pc so that the potential felt by the disk is nearly Keplerian. The disk eccentricity may be excited by a secular instability driven by dynamical friction from the bulge.

Scott Tremaine

1995-02-13T23:59:59.000Z

255

PROTOPLANETARY DISK STRUCTURE WITH GRAIN EVOLUTION: THE ANDES MODEL  

SciTech Connect

We present a self-consistent model of a protoplanetary disk: 'ANDES' ('AccretioN disk with Dust Evolution and Sedimentation'). ANDES is based on a flexible and extendable modular structure that includes (1) a 1+1D frequency-dependent continuum radiative transfer module, (2) a module to calculate the chemical evolution using an extended gas-grain network with UV/X-ray-driven processes and surface reactions, (3) a module to calculate the gas thermal energy balance, and (4) a 1+1D module that simulates dust grain evolution. For the first time, grain evolution and time-dependent molecular chemistry are included in a protoplanetary disk model. We find that grain growth and sedimentation of large grains onto the disk midplane lead to a dust-depleted atmosphere. Consequently, dust and gas temperatures become higher in the inner disk (R {approx}< 50 AU) and lower in the outer disk (R {approx}> 50 AU), in comparison with the disk model with pristine dust. The response of disk chemical structure to the dust growth and sedimentation is twofold. First, due to higher transparency a partly UV-shielded molecular layer is shifted closer to the dense midplane. Second, the presence of big grains in the disk midplane delays the freeze-out of volatile gas-phase species such as CO there, while in adjacent upper layers the depletion is still effective. Molecular concentrations and thus column densities of many species are enhanced in the disk model with dust evolution, e.g., CO{sub 2}, NH{sub 2}CN, HNO, H{sub 2}O, HCOOH, HCN, and CO. We also show that time-dependent chemistry is important for a proper description of gas thermal balance.

Akimkin, V.; Wiebe, D.; Pavlyuchenkov, Ya. [Institute of Astronomy of the RAS, Pyatnitskaya str. 48, Moscow (Russian Federation)] [Institute of Astronomy of the RAS, Pyatnitskaya str. 48, Moscow (Russian Federation); Zhukovska, S.; Semenov, D.; Henning, Th. [Max-Planck-Institute for Astronomy, Koenigstuhl 17, D-69117 Heidelberg (Germany)] [Max-Planck-Institute for Astronomy, Koenigstuhl 17, D-69117 Heidelberg (Germany); Vasyunin, A. [Department of Chemistry, The University of Virginia, VA (United States)] [Department of Chemistry, The University of Virginia, VA (United States); Birnstiel, T., E-mail: akimkin@inasan.ru, E-mail: dwiebe@inasan.ru, E-mail: pavyar@inasan.ru, E-mail: zhukovska@mpia.de, E-mail: semenov@mpia.de, E-mail: henning@mpia.de, E-mail: anton.vasyunin@gmail.com, E-mail: tbirnstiel@cfa.harvard.edu [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States)

2013-03-20T23:59:59.000Z

256

PAH chemistry and IR emission from circumstellar disks  

E-Print Network (OSTI)

Aims. The chemistry of, and infrared (IR) emission from, polycyclic aromatic hydrocarbons (PAHs) in disks around Herbig Ae/Be and T Tauri stars are investigated. The equilibrium distribution of the PAHs over all accessible charge/hydrogenation states depends on the size and shape of the PAHs and on the physical properties of the star and surrounding disk. Methods. A chemistry model is created to calculate this equilibrium distribution. Destruction of PAHs by ultraviolet (UV) photons, possibly in multi-photon absorption events, is taken into account. The chemistry model is coupled to a radiative transfer code to provide the physical parameters and to combine the PAH emission with the spectral energy distribution (SED) from the star+disk system. Results. Normally hydrogenated PAHs in Herbig Ae/Be disks account for most of the observed PAH emission, with neutral and positively ionized species contributing in roughly equal amounts. Close to the midplane, the PAHs are more strongly hydrogenated and negatively ionized, but these species do not contribute to the overall emission because of the low UV/optical flux deep inside the disk. PAHs of 50 carbon atoms are destroyed out to 100 AU in the disk's surface layer, and the resulting spatial extent of the emission does not agree well with observations. Rather, PAHs of about 100 carbon atoms or more are predicted to cause most of the observed emission. The emission is extended on a scale similar to that of the size of the disk. Furthermore, the emission from T Tauri disks is much weaker and concentrated more towards the central star than that from Herbig Ae/Be disks. Positively ionized PAHs are predicted to be largely absent in T Tauri disks because of the weaker radiation field.

R. Visser; V. C. Geers; C. P. Dullemond; J. -C. Augereau; K. M. Pontoppidan; E. F. van Dishoeck

2007-01-22T23:59:59.000Z

257

MHD Stellar and Disk Winds: Application to Planetary Nebulae  

E-Print Network (OSTI)

MHD winds can emanate from both stars and surrounding accretion disks. It is of interest to know how much wind power is available and which (if either) of the two rotators dominates that power. We investigate this in the context of multi-polar planetary nebulae (PNe) and proto-planetary nebulae (PPNe), for which recent observations have revealed the need for a wind power source in excess of that available from radiation driving, and a possible need for magnetic shaping. We calculate the MHD wind power from a coupled disk and star, where the former results from binary disruption. The resulting wind powers depend only on the accretion rate and stellar properties. We find that if the stellar envelope were initially slowly rotating, the disk wind would dominate throughout the evolution. If the envelope of the star were rapidly rotating, the stellar wind could initially be of comparable power to the disk wind until the stellar wind carries away the star's angular momentum. Since an initially rapidly rotating star can have its spin and magnetic axes misaligned to the disk, multi-polar outflows can result from this disk wind system. For times greater than a spin-down time, the post-AGB stellar wind is slaved to the disk for both slow and rapid initial spin cases and the disk wind luminosity dominates. We find a reasonably large parameter space where a hybrid star+disk MHD driven wind is plausible and where both or either can account for PPNe and PNe powers. We also speculate on the morphologies which may emerge from the coupled system. The coupled winds might help explain the shapes of a number of remarkable multi-shell or multi-polar nebulae. Magnetic activity such as X-ray flares may be associated with the both central star and the disk and would be a valuable diagnostic for the dynamical role of MHD processes in PNe.

Eric G. Blackman; Adam Frank; Carl Welch

2000-05-12T23:59:59.000Z

258

E-Print Network 3.0 - accretion disk flows Sample Search Results  

NLE Websites -- All DOE Office Websites (Extended Search)

39 Manuel Gdel Switzerland Summary: II Diagnoses Different Regions Rkm.com.au disk wind, photoevap. flow jet accretion columns 12;END 12;... - stellar? (Taurus) Disk...

259

E-Print Network 3.0 - accretion disks crystalline Sample Search...  

NLE Websites -- All DOE Office Websites (Extended Search)

(MIT) Collection: Physics 87 SPECTRAL ENERGY DISTRIBUTIONS OF PASSIVE T TAURI DISKS: INCLINATION Summary: --- stars: pre- main sequence --- accretion, accretion disks ---...

260

DISK CORONA INTERACTION: MECHANISM FOR THE DISK TRUNCATION AND SPECTRUM CHANGE IN LOW-LUMINOSITY ACTIVE GALACTIC NUCLEI  

SciTech Connect

The truncation of an optically thick, geometrically thin accretion disk is investigated in the context of low-luminosity AGNs (LLAGNs). We generalize the disk evaporation model used in the interpretative framework of black hole X-ray binaries by including the effect of a magnetic field in accretion disks surrounding supermassive black holes. The critical transition mass accretion rate for which the disk is truncated is found to be insensitive to magnetic effects, but its inclusion leads to a smaller truncation radius in comparison to a model without its consideration. That is, a thin viscous disk is truncated for LLAGNs at an Eddington ratio less than 0.03 for a standard viscosity parameter ({alpha} = 0.3). An increase of the viscosity parameter results in a higher critical transition mass accretion rate and a correspondingly smaller truncation distance, the latter accentuated by greater magnetic energy densities in the disk. Based on these results, the truncation radii inferred from spectral fits of LLAGNs published in the literature are consistent with the disk evaporation model. The infrared emission arising from the truncated geometrically thin accretion disks may be responsible for the red bump seen in such LLAGNs.

Taam, Ronald E. [Academia Sinica Institute of Astronomy and Astrophysics-TIARA, P.O. Box 23-141, Taipei 10617, Taiwan (China); Liu, B. F.; Yuan, W.; Qiao, E., E-mail: r-taam@northwestern.edu, E-mail: bfliu@nao.cas.cn [National Astronomical Observatories, Chinese Academy of Sciences, 20A Datun Road, Chaoyang District, Beijing 100012 (China)

2012-11-01T23:59:59.000Z

Note: This page contains sample records for the topic "brakes front disk" from the National Library of EnergyBeta (NLEBeta).
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261

Planetesimal Capture in the Disk Instability Model  

E-Print Network (OSTI)

We follow the contraction and evolution of a typical Jupiter-mass clump created by the disk instability mechanism, and compute the rate of planetesimal capture during this evolution. We show that such a clump has a slow contraction phase lasting ~3x10^5 years. By following the trajectories of planetesimals as they pass through the envelope of the protoplanet, we compute the cross-section for planetesimal capture at all stages of the protoplanet's evolution. We show that the protoplanet can capture a large fraction of the solid material in its feeding zone, which will lead to an enrichment of the protoplanet in heavy elements. The exact amount of this enrichment depends upon, but is not very sensitive to the size and random speed of the planetesimals.

Ravit Helled; Morris Podolak; Attay Kovetz

2006-06-29T23:59:59.000Z

262

The Cosmic Battery in Astrophysical Accretion Disks  

E-Print Network (OSTI)

The aberrated radiation pressure at the inner edge of the accretion disk around an astrophysical black hole imparts a relative azimuthal velocity on the electrons with respect to the ions which gives rise to a ring electric current that generates large scale poloidal magnetic field loops. This is the Cosmic Battery established by Contopoulos and Kazanas in 1998. In the present work we perform realistic numerical simulations of this important astrophysical mechanism in advection-dominated accretion flows-ADAF. We confirm the original prediction that the inner parts of the loops are continuously advected toward the central black hole and contribute to the growth of the large scale magnetic field, whereas the outer parts of the loops are continuously diffusing outward through the turbulent accretion flow. This process of inward advection of the axial field and outward diffusion of the return field proceeds all the way to equipartition, thus generating astrophysically significant magnetic fields on astrophysicall...

Contopoulos, Ioannis; Katsanikas, Matthaios

2015-01-01T23:59:59.000Z

263

TESTING CONVERGENCE FOR GLOBAL ACCRETION DISKS  

SciTech Connect

Global disk simulations provide a powerful tool for investigating accretion and the underlying magnetohydrodynamic turbulence driven by magneto-rotational instability (MRI). Using them to accurately predict quantities such as stress, accretion rate, and surface brightness profile requires that purely numerical effects, arising from both resolution and algorithm, be understood and controlled. We use the flux-conservative Athena code to conduct a series of experiments on disks having a variety of magnetic topologies to determine what constitutes adequate resolution. We develop and apply several resolution metrics: (Q{sub z} ) and (Q{sub {phi}}), the ratio of the grid zone size to the characteristic MRI wavelength, {alpha}{sub mag}, the ratio of the Maxwell stress to the magnetic pressure, and /, the ratio of radial to toroidal magnetic field energy. For the initial conditions considered here, adequate resolution is characterized by (Q{sub z} ) {>=} 15, (Q{sub {phi}}) {>=} 20, {alpha}{sub mag} Almost-Equal-To 0.45, and /{approx}0.2. These values are associated with {>=}35 zones per scaleheight H, a result consistent with shearing box simulations. Numerical algorithm is also important. Use of the Harten-Lax-van Leer-Einfeldt flux solver or second-order interpolation can significantly degrade the effective resolution compared to the Harten-Lax-van Leer discontinuities flux solver and third-order interpolation. Resolution at this standard can be achieved only with large numbers of grid zones, arranged in a fashion that matches the symmetries of the problem and the scientific goals of the simulation. Without it, however, quantitative measures important to predictions of observables are subject to large systematic errors.

Hawley, John F.; Richers, Sherwood A.; Guan Xiaoyue [Department of Astronomy, University of Virginia, P.O. Box 400325, Charlottesville, VA 22904-4325 (United States); Krolik, Julian H., E-mail: jh8h@virginia.edu, E-mail: xg3z@virginia.edu, E-mail: jhk@pha.jhu.edu [Department of Physics and Astronomy, Johns Hopkins University, Baltimore, MD 21218 (United States)

2013-08-01T23:59:59.000Z

264

DEBRIS DISKS IN KEPLER EXOPLANET SYSTEMS  

SciTech Connect

The Kepler mission recently identified 997 systems hosting candidate extrasolar planets, many of which are super-Earths. Realizing these planetary systems are candidates to host extrasolar asteroid belts, we use mid-infrared data from the Wide-field Infrared Survey Explorer (WISE) to search for emission from dust in these systems. We find excesses around eight stars, indicating the presence of warm to hot dust ({approx}100-500 K), corresponding to orbital distances of 0.1-10 AU for these solar-type stars. The strongest detection, KOI 1099, demands {approx}500 K dust interior to the orbit of its exoplanet candidate. One star, KOI 904, may host very hot dust ({approx}1200 K, corresponding to 0.02 AU). Although the fraction of these exoplanet-bearing stars with detectable warm excesses ({approx}3%) is similar to that found by Spitzer surveys of solar-type field stars, the excesses detectable in the WISE data have much higher fractional luminosities (L{sub dust}/L{sub *}) than most known debris disks, implying that the fraction with debris disks of comparable luminosity may actually be significantly higher. It is difficult to explain the presence of dust so close to the host stars, generally corresponding to dust rings at radii <0.3 AU; both the collisional and Poynting-Robertson drag timescales to remove dust from the system are hundreds of years or less at these distances. Assuming a steady state for these systems implies large mass consumption rates with these short removal timescales, meaning that the dust production mechanism in these systems must almost certainly be episodic in nature.

Lawler, S. M.; Gladman, B. [Department of Physics and Astronomy, University of British Columbia, 6244 Agricultural Road, Vancouver, BC V6T 1Z1 (Canada)

2012-06-10T23:59:59.000Z

265

Barium even-to-odd isotope abundance ratios in thick disk and thin disk stars  

E-Print Network (OSTI)

We present the Ba even-to-odd isotope abundance ratios in 25 cool dwarf stars with the metallicity [Fe/H] ranged between 0.25 and --1.35. Our method takes advantage of the hyperfine structure (HFS) affecting the \\ion{Ba}{ii} resonance line of the odd isotopes. The fractional abundance of the odd isotopes of Ba is derived from a requirement that Ba abundances from the resonance line $\\lambda 4554$ and subordinate lines $\\lambda 5853$ and $\\lambda 6496$ must be equal. The results are based on NLTE line formation and analysis of high resolution (R $\\sim60000$) high signal-to-noise (S/N $\\ge 200$) observed spectra. We find that the fraction of the odd isotopes of Ba grows toward the lower Ba abundance (or metallicity) and the mean value in the thick disk stars equals 33 $\\pm$ 4%. This indicates the higher contribution of the $r-$process to barium in the thick disk stars compared to the solar system matter. The obtained fraction increases with the [Eu/Ba] abundance ratio growth in agreement with expectations. A significant fraction of the \\emph{even} isotopes of Ba found in old Galactic stars (the thick disk stars), $\\sim67$%, is in contrast to the prediction of the "classical" model of the $s-$process and favors the value predicted by the "stellar" models of Arlandini et al. (1999) and Travaglio et al. (1999).

L. Mashonkina; G. Zhao

2006-04-10T23:59:59.000Z

266

DYNAMICAL EVOLUTION OF VISCOUS DISKS AROUND Be STARS. I. PHOTOMETRY  

SciTech Connect

Be stars possess gaseous circumstellar disks that modify in many ways the spectrum of the central B star. Furthermore, they exhibit variability at several timescales and for a large number of observables. Putting the pieces together of this dynamical behavior is not an easy task and requires a detailed understanding of the physical processes that control the temporal evolution of the observables. There is an increasing body of evidence that suggests that Be disks are well described by standard {alpha}-disk theory. This paper is the first of a series that aims at studying the possibility of inferring several disk and stellar parameters through the follow-up of various observables. Here we study the temporal evolution of the disk density for different dynamical scenarios, including the disk build-up as a result of a long and steady mass injection from the star, the disk dissipation that occurs after mass injection is turned off, as well as scenarios in which active periods are followed by periods of quiescence. For those scenarios, we investigate the temporal evolution of continuum photometric observables using a three-dimensional non-LTE radiative transfer code. We show that light curves for different wavelengths are specific of a mass loss history, inclination angle, and {alpha} viscosity parameter. The diagnostic potential of those light curves is also discussed.

Haubois, X.; Carciofi, A. C. [Instituto de Astronomia, Geofisica e Ciencias Atmosfericas, Universidade de Sao Paulo, Rua do Matao 1226, Cidade Universitaria, Sao Paulo, SP 05508-900 (Brazil); Rivinius, Th. [European Organisation for Astronomical Research in the Southern Hemisphere, Casilla 19001, Santiago 19 (Chile); Okazaki, A. T. [Faculty of Engineering, Hokkai-Gakuen University, Toyohira-ku, Sapporo 062-8605 (Japan); Bjorkman, J. E., E-mail: xhaubois@astro.iag.usp.br [Ritter Observatory, Department of Physics and Astronomy, University of Toledo, Toledo, OH 43606 (United States)

2012-09-10T23:59:59.000Z

267

WATER VAPOR IN THE PROTOPLANETARY DISK OF DG Tau  

SciTech Connect

Water is key in the evolution of protoplanetary disks and the formation of comets and icy/water planets. While high-excitation water lines originating in the hot inner disk have been detected in several T Tauri stars (TTSs), water vapor from the outer disk, where most water ice reservoirs are stored, was only reported in the nearby TTS TW Hya. We present spectrally resolved Herschel/HIFI observations of the young TTS DG Tau in the ortho- and para-water ground-state transitions at 557 and 1113 GHz. The lines show a narrow double-peaked profile, consistent with an origin in the outer disk, and are {approx}19-26 times brighter than in TW Hya. In contrast, CO and [C II] lines are dominated by emission from the envelope/outflow, which makes H{sub 2}O lines a unique tracer of the disk of DG Tau. Disk modeling with the thermo-chemical code ProDiMo indicates that the strong UV field, due to the young age and strong accretion of DG Tau, irradiates a disk upper layer at 10-90 AU from the star, heating it up to temperatures of 600 K and producing the observed bright water lines. The models suggest a disk mass of 0.015-0.1 M{sub Sun }, consistent with the estimated minimum mass of the solar nebula before planet formation, and a water reservoir of {approx}10{sup 2}-10{sup 3} Earth oceans in vapor and {approx}100 times larger in the form of ice. Hence, this detection supports the scenario of ocean delivery on terrestrial planets by the impact of icy bodies forming in the outer disk.

Podio, L.; Dougados, C.; Thi, W.-F.; Menard, F.; Pinte, C. [UJF-Grenoble 1/CNRS-INSU, Institut de Planetologie et d'Astrophysique de Grenoble (IPAG) UMR 5274, F-38041 Grenoble (France); Kamp, I.; Meijerink, R.; Spaans, M.; Aresu, G. [Kapteyn Astronomical Institute, University of Groningen, Landleven 12, 9747 AD Groningen (Netherlands); Codella, C. [INAF-Osservatorio Astrofisico di Arcetri, Largo E. Fermi 5, I-50125 Florence (Italy); Cabrit, S. [LERMA, UMR 8112 du CNRS, Observatoire de Paris, Ecole Normale Superieure, Universite Pierre et Marie Curie, Universite de Cergy-Pontoise, 61 Av. de l'Observatoire, F-75014 Paris (France); Nisini, B. [INAF-Osservatorio Astronomico di Roma, via di Frascati 33, I-00040 Monte Porzio Catone (Italy); Sandell, G. [SOFIA-USRA, NASA Ames Research Center, MS 232-12, Building N232, Rm. 146, P.O. Box 1, Moffett Field, CA 94035-0001 (United States); Williams, J. P. [Institute for Astronomy (IfA), University of Hawaii, 2680 Woodlawn Dr., Honolulu, HI 96822 (United States); Testi, L. [European Southern Observatory, Karl-Schwarzschild-Strasse 2, D-85748 Garching (Germany); Woitke, P. [SUPA, School of Physics and Astronomy, University of St. Andrews, KY16 9SS (United Kingdom)

2013-03-20T23:59:59.000Z

268

Corrections to kinetic measurements taken on a disk electrode  

SciTech Connect

Below the limiting current, the rotating disk electrode has a nonuniform current distribution. When the nonuniformities are not explicitly accounted for, errors in values of kinetic parameters determined through measurements on a disk can result. In this analysis, valid for Tafel kinetics, correction factors are obtained as a function of the dimensionless average current density.It is assumed that ohmic corrections are made by the interruption of current. The results indicate that, under certain conditions, the errors are negligible and that the disk geometry, despite its nonuniformities, is adequate for the investigation of systems characterized by Tafel kinetics.

West, A.C.; Newman, J.

1989-01-01T23:59:59.000Z

269

Characteristics of a multiple disk pump with turbulent rotor flow  

E-Print Network (OSTI)

DIRHETER IINIt tl, DISCHARGE OIANETER IINlt 3. CLEARANCE OETHEEN DISKS 0. 13636 IN. TYPE SEALJ PRCKING DISKFLO PUHP; NODEL K03 TOTRL HERO HORSEPOHER X EFFICIENCY + NPSH AVAIL V Figure 12. Performance of the 11 Disk Pump at 890 rpm (Test 2) C& C...: D. 13636 IN 111'E 5EAI. PACK(NO OISKFLD PL'. "P: HDD L 40 TOTAL HERO HDRSEPOHER X EFFICIENCY + NPSH AVAIL Y Figure 14 . Performance of the 1 1 Disk Pump at 1 790 rpm ( Tes t 1 ) CV o O C) CI O C) O \\ C CC C O I-!-W I o O O O 6 )3...

Roddy, Patrick James

1985-01-01T23:59:59.000Z

270

Front surface thermal property measurements of air plasma spray coatings  

SciTech Connect

A front-surface measurement for determining the thermal properties of thermal barrier coatings has been applied to air plasma spray coatings. The measurement is used to determine all independent thermal properties of the coating simultaneously. Furthermore, with minimal requirements placed on the sample and zero sample preparation, measurements can be made under previously impossible conditions, such as on serviceable engine parts. Previous application of this technique was limited to relatively thin coatings, where a one-dimensional heat transfer model is applied. In this paper, the influence of heat spreading on the measurement of thicker coatings is investigated with the development of a two-dimensional heat transfer model.

Bennett, Ted; Kakuda, Tyler [University of California, Santa Barbara, California 93106-5070 (United States); Kulkarni, Anand [Siemens Energy, Orlando, Florida 32826-2399 (United States)

2009-04-15T23:59:59.000Z

271

Exciton front propagation in photoexcited GaAs quantum wells  

Science Journals Connector (OSTI)

We report on the study of spatiotemporal self-organization of carriers in photoexcited GaAs quantum wells. Propagating interfaces between electron-rich and hole-rich regions are seen as expanding and collapsing exciton rings in exciton emission patterns. The interfaces preserve their integrity during expansion, remaining as sharp as in the steady state, which indicates that the dynamics is controlled by carrier transport. The front propagation velocity is measured and compared to theoretical model. The measurements of expanding and collapsing exciton rings afford a contactless method for probing the electron and hole transport.

Sen Yang, L. V. Butov, L. S. Levitov, B. D. Simons, and A. C. Gossard

2010-03-16T23:59:59.000Z

272

Pinpointing Chiral Structures with Front-Back Polarized Neutron Reflectometry  

Science Journals Connector (OSTI)

A new development in spin-polarized neutron reflectometry enables us to more fully characterize the nucleation and growth of buried domain walls in layered magnetic materials. We applied this technique to a thin-film exchange-spring magnet. After first measuring the reflectivity with the neutrons striking the front, we measure with the neutrons striking the back. Simultaneous fits are sensitive to the presence of spiral spin structures. The technique reveals previously unresolved features of field-dependent domain walls in exchange-spring systems and has sufficient generality to apply to a variety of magnetic systems.

K. V. O'Donovan; J. A. Borchers; C. F. Majkrzak; O. Hellwig; E. E. Fullerton

2002-01-25T23:59:59.000Z

273

New RPC front-end electronics for hades  

E-Print Network (OSTI)

Time-of-flight (TOF) detectors are mainly used for both particle identification and triggering. Resistive Plate Chamber (RPC) detectors are becoming widely used because of their excellent TOF capabilities and reduced cost. The new ESTRELA* RPC wall, which is being installed in the HADES detector at Darmstadt GSI, will contain 1024 RPC modules, covering an active area of around 7 m2. It has excellent TOF and good charge resolutions. Its Front-End electronics is based on a 8-layer Mother-Board providing impedance matched paths for the output signals of each of the eight 4-channel Daughter-Boards to the TDC.

Gil, Alejandro; Cabanelas, P; Daz, J; Garzn, J A; Gonzlez-Daz, D; Knig, W; Lange, J S; Marn, J; Montes, N; Skott, P; Traxler, M

2007-01-01T23:59:59.000Z

274

LARGE-SCALE CORONAL PROPAGATING FRONTS IN SOLAR ERUPTIONS AS OBSERVED BY THE ATMOSPHERIC IMAGING ASSEMBLY ON BOARD THE SOLAR DYNAMICS OBSERVATORYAN ENSEMBLE STUDY  

SciTech Connect

This paper presents a study of a large sample of global disturbances in the solar corona with characteristic propagating fronts as intensity enhancement, similar to the phenomena that have often been referred to as Extreme Ultraviolet Imaging Telescope (EIT) waves or extreme-ultraviolet (EUV) waves. Now EUV images obtained by the Atmospheric Imaging Assembly (AIA) on board the Solar Dynamics Observatory provide a significantly improved view of these large-scale coronal propagating fronts (LCPFs). Between 2010 April and 2013 January, a total of 171 LCPFs have been identified through visual inspection of AIA images in the 193 channel. Here we focus on the 138 LCPFs that are seen to propagate across the solar disk, first studying how they are associated with flares, coronal mass ejections (CMEs), and type II radio bursts. We measure the speed of the LCPF in various directions until it is clearly altered by active regions or coronal holes. The highest speed is extracted for each LCPF. It is often considerably higher than EIT waves. We do not find a pattern where faster LCPFs decelerate and slow LCPFs accelerate. Furthermore, the speeds are not strongly correlated with the flare intensity or CME magnitude, nor do they show an association with type II bursts. We do not find a good correlation either between the speeds of LCPFs and CMEs in a subset of 86 LCPFs observed by one or both of the Solar and Terrestrial Relations Observatory spacecraft as limb events.

Nitta, Nariaki V.; Schrijver, Carolus J.; Title, Alan M.; Liu, Wei [Lockheed Martin Advanced Technology Center, Dept/A021S, B/252, 3251 Hanover Street, Palo Alto, CA 94304 (United States)

2013-10-10T23:59:59.000Z

275

SmartSaver: Turning Flash Drive into a Disk Energy Saver for Mobile , Song Jiang2  

E-Print Network (OSTI)

- cies usually take conservative approaches to save disk energy, and disk energy consumption remains drive -- saving disk energy. This is achieved by using the flash drive as a standby buffer for caching to 41% of disk energy can be saved with a relatively small amount of data written to the flash drive

276

HyLog: A High Performance Approach to Managing Disk Layout  

Science Journals Connector (OSTI)

Our objective is to improve disk I/O performance in multi-disk systems supporting multiple concurrent users, such as file servers, database servers, and email servers. In such systems, many disk reads are absorbed by large in-memory buffers, and so disk ...

Wenguang Wang; Yanping Zhao; Rick Bunt

2004-03-01T23:59:59.000Z

277

HyLog: a high performance approach to managing disk layout  

Science Journals Connector (OSTI)

Our objective is to improve disk I/O performance in multi-disk systems supporting multiple concurrent users, such as file servers, database servers, and email servers. In such systems, many disk reads are absorbed by large in-memory buffers, and so disk ...

Wenguang Wang; Yanping Zhao; Rick Bunt

2004-03-01T23:59:59.000Z

278

Breaking the Disk/Halo Degeneracy with Gravitational Lensing  

E-Print Network (OSTI)

The degeneracy between the disk and the dark matter contribution to galaxy rotation curves remains an important uncertainty in our understanding of disk galaxies. Here we discuss a new method for breaking this degeneracy using gravitational lensing by spiral galaxies, and apply this method to the spiral lens B1600+434 as an example. The combined image and lens photometry constraints allow models for B1600+434 with either a nearly singular dark matter halo, or a halo with a sizable core. A maximum disk model is ruled out with high confidence. Further information, such as the circular velocity of this galaxy, will help break the degeneracies. Future studies of spiral galaxy lenses will be able to determine the relative contribution of disk, bulge, and halo to the mass in the inner parts of galaxies.

Ariyeh H. Maller; Luc Simard; Puragra Guhathakurta; Jens Hjorth; Andreas O. Jaunsen; Ricardo A. Flores; Joel R. Primack

1999-10-12T23:59:59.000Z

279

Backscattering cross section of a tilted, roughened disk  

Science Journals Connector (OSTI)

An expression is derived for the cross correlation of the electric field scattered from a roughened metallic disk to two points in the far zone. Both exponential and Gaussian surface...

Schertler, Donald J; George, Nicholas

1992-01-01T23:59:59.000Z

280

Zooming in on quasar accretion disks using chromatic microlensing  

E-Print Network (OSTI)

Observing the temperature profiles of accretion disks around black holes is a fundamental test of an important astrophysical process. However, angular resolution limitations have prevented such a measurement for distant ...

Blackburne, Jeffrey A

2009-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "brakes front disk" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


281

Data partitioning and load balancing in parallel disk systems  

Science Journals Connector (OSTI)

...Parallel disk systems provide opportunities for exploiting I/O parallelism in two possible ways, namely via inter-request and intra-request parallelism. In this paper, we discuss the main issues in performance...

Peter Scheuermann; Gerhard Weikum; Peter Zabback

1998-02-01T23:59:59.000Z

282

Modeling Disk Arrays Using Genetic Programming Evan Kirshenbaum  

E-Print Network (OSTI)

Page Mill Road Palo Alto, CA 94304 kirshenbaum@hpl.hp.com Abstract This paper describes the results to population size but not run length. 1 BACKGROUND In the past decade, enterprises have turned to disk arrays

Fernandez, Thomas

283

Modeling Adhesive Forces for Ultra Low Flying Head Disk Interfaces  

Science Journals Connector (OSTI)

This paper addresses a major issue in microtribology related to the head/disk interface (HDI) in magnetic storage. This is the issue of strong intermolecular (adhesive) forces that may be present at the interf...

Andreas A. Polycarpou

2003-01-01T23:59:59.000Z

284

Innovation incentives and competition in the hard disk drive industry  

E-Print Network (OSTI)

Firms in the hard disk drive industry are continually engaging in R & D and improving the quality of their products. We explore various determinants of the product innovation incentives for firms concerned with both their ...

Wu, Xiaohua Sherry

2011-01-01T23:59:59.000Z

285

Nanolithographically defined magnetic structures and quantum magnetic disk (invited)  

E-Print Network (OSTI)

is demonstrated along with a low-cost method for mass producing such disks. Other impacts that nanofabrication can- veloped in a cellosolve and methanol solution to form a re- sist template on the substrate. Ferromagnetic

286

Detecting planets in protoplanetary disks: A prospective study  

E-Print Network (OSTI)

We investigate the possibility to find evidence for planets in circumstellar disks by infrared and submillimeter interferometry. We present simulations of a circumstellar disk around a solar-type star with an embedded planet of 1 Jupiter mass. The three-dimensional (3D) density structure of the disk results from hydrodynamical simulations. On the basis of 3D radiative transfer simulations, images of this system were calculated. The intensity maps provide the basis for the simulation of the interferometers VLTI (equipped with the mid-infrared instrument MIDI) and ALMA. While MIDI/VLTI will not provide the possibility to distinguish between disks with or without a gap on the basis of visibility measurements, ALMA will provide the necessary basis for a direct gap detection.

S. Wolf; F. Gueth; Th. Henning; W. Kley

2002-01-12T23:59:59.000Z

287

Photophoresis in protoplanetary disks: a numerical approach  

E-Print Network (OSTI)

It is widely accepted that rocky planets form in the inner regions of protoplanetary disks (PPD) about 1 - 10 AU from the star. However, theoretical calculations show that when particles reach the size for which the radial migration is the fastest they tend to be accreted very efficiently by the star. This is known as the radial-drift barrier. We explore the photophoresis in the inner regions of PPD as a possible mechanism for preventing the accretion of solid bodies onto the star. Photophoresis is the thermal creep induced by the momentum exchange of an illuminated solid particle with the surrounding gas. Recent laboratory experiments predict that photophoresis would be able to stop the inward drift of macroscopic bodies (from 1 mm to 1 m in size). This extra force has been included in our two-fluid (gas+dust) SPH code in order to study its efficiency. We show that the conditions of pressure and temperature encountered in the inner regions of PPD result in strong dynamical effects on the dust particles due t...

Cuello, Nicolas; Gonzalez, Jean-Franois

2014-01-01T23:59:59.000Z

288

The dynamics of combustion fronts in porous media  

SciTech Connect

In this report, a method for solving this problem by treating the reaction region as a place of discontinuities in the appropriate variables, which include, for example, fluxes of heat and mass was proposed. Using a rigorous perturbation approach, similar to that used in the propagation of flames and smoldering combustion, appropriate jump conditions that relate the change in these variables across the front was derived. These conditions account for the kinetics of the reaction between the oxidant and the fuel, the changes in the morphology of the pore space and the heat and mass transfer in the reaction zone. The modeling of the problem reduces to the modeling of the dynamics of a combustion front, on the regions of either side of which transport of momentum (fluids), heat and mass, but not chemical reactions, must be considered. Properties of the two regions are coupled using the derived jump conditions. This methodology allows one to explicitly incorporate permeability heterogeneity effects in the process description, without the undue complexity of the coupled chemical reactions.

Akkutlu, I. Yucel; Yortsos, Yannis C.

2000-06-15T23:59:59.000Z

289

Large grains in the disk of CQ Tau  

E-Print Network (OSTI)

We present 7mm observations of the dusty disk surrounding the 10 Myr old 1.5 Msun pre-main-sequence star CQ Tauri obtained at the Very Large Array with 0.8 arcsecond resolution and 0.1 mJy rms sensitivity. These observations resolve the 7mm emission in approximately the north-south direction, confirming previous results obtained with lower resolution. We use a two-layer flared disk model to interpret the observed fluxes from 7mm to 1.3mm together with the resolved 7mm structure. We find that the disk radius is constrained to the range 100 to 300 AU, depending on the steepness of the disk surface density distribution. The power law index of the dust opacity coefficient, beta, is constrained to be 0.5 to 0.7. Since the models indicate that the disk is optically thin at millimeter wavelengths for radii greater than 8 AU, the contribution of an optically thick region to the emission is less than 10%. This implies that high optical depth or complex disk geometry cannot be the cause of the observed shallow millimeter spectral index. Instead, the new analysis supports the earlier suggestion that dust particles in the disk have grown to sizes as large as a few centimeters. The dust in the CQ Tauri system appears to be evolved much like that in the TW Hydra system, a well-studied pre-main-sequence star of similar age and lower mass. The survival of gas-rich disks with incomplete grain evolution at such old ages deserves further investigations.

L. Testi; A. Natta; D. S. Shepherd; D. J. Wilner

2003-03-18T23:59:59.000Z

290

STAR CLUSTER POPULATIONS IN THE OUTER DISKS OF NEARBY GALAXIES  

SciTech Connect

We present a Large Binocular Telescope imaging study that characterizes the star cluster component of nearby galaxy outer disks (beyond the optical radius R{sub 25}). Expanding on the pilot project of Herbert-Fort et al., we present deep ({approx}27.5 mag V-band point-source limiting magnitude) U- and V-band imaging of six galaxies: IC 4182, NGC 3351, NGC 4736, NGC 4826, NGC 5474, and NGC 6503. We find that the outer disk of each galaxy is populated with marginally resolved star clusters with masses {approx}10{sup 3} M{sub Sun} and ages up to {approx}1 Gyr (masses and ages are limited by the depth of our imaging and uncertainties are large given how photometry can be strongly affected by the presence or absence of a few stars in such low-mass systems), and that they are typically found out to at least 2 R{sub 25} but sometimes as far as 3-4 R{sub 25}-even beyond the apparent H I disk. The mean rate of cluster formation for 1 R{sub 25} {<=} R {<=} 1.5 R{sub 25} is at least one every {approx}2.5 Myr and the clusters are spatially correlated with the H I, most strongly with higher density gas near the periphery of the optical disk and with lower density neutral gas at the H I disk periphery. We hypothesize that the clusters near the edge of the optical disk are formed in the extension of spiral structure from the inner disk and are a fairly consistent phenomenon and that the clusters formed at the periphery of the H I disk are the result of accretion episodes.

Herbert-Fort, Stephane; Zaritsky, Dennis [Department of Astronomy/Steward Observatory, University of Arizona, 933 N Cherry Avenue, Tucson, AZ 85721 (United States); Moustakas, John [Center for Astrophysics and Space Sciences, University of California, San Diego, La Jolla, CA 92093 (United States); Di Paola, Andrea [INAF, Osservatorio Astronomico di Roma, via di Frascati 33, I-00040 Monteporzio (Italy); Pogge, Richard W. [Department of Astronomy, Ohio State University, 140 W. 18th Avenue, Columbus, OH 43210-1173 (United States); Ragazzoni, Roberto, E-mail: s.herbertfort@gmail.com, E-mail: dennis.zaritsky@gmail.com [INAF, Osservatorio Astronomico di Padova, vicolo dell'Osservatorio 5, I-35122 Padova (Italy)

2012-08-01T23:59:59.000Z

291

Apparatus and method for pressure testing closure disks  

DOE Patents (OSTI)

A method and device are described for testing the burst pressure of closure disks which provides high pressure to both sides of a disk and rapidly releases pressure from one side thereof causing a high rate of change of pressure. A hollow notched plug allows the rapid release of pressure upon rupturing. A tensile load is transmitted by a piston in combination with fluid pressure to the hollow notched plug. 5 figs.

Merten, C.W. Jr.

1992-01-21T23:59:59.000Z

292

Identification of new transitional disk candidates in Lupus with Herschel  

E-Print Network (OSTI)

New data from the Herschel Space Observatory are broadening our understanding of the physics and evolution of the outer regions of protoplanetary disks in star forming regions. In particular they prove to be useful to identify transitional disk candidates. The goals of this work are to complement the detections of disks and the identification of transitional disk candidates in the Lupus clouds with data from the Herschel Gould Belt Survey. We extracted photometry at 70, 100, 160, 250, 350 and 500 $\\mu$m of all spectroscopically confirmed Class II members previously identified in the Lupus regions and analyzed their updated spectral energy distributions. We have detected 34 young disks in Lupus in at least one Herschel band, from an initial sample of 123 known members in the observed fields. Using the criteria defined in Ribas et al. (2013) we have identified five transitional disk candidates in the region. Three of them are new to the literature. Their PACS-70 $\\mu$m fluxes are systematically higher than thos...

Bustamante, I; Ribas, ; Bouy, H; Prusti, T; Pilbratt, G L; Andr, Ph

2015-01-01T23:59:59.000Z

293

Merger Histories of Galaxy Halos and Implications for Disk Survival  

E-Print Network (OSTI)

We study the merger histories of galaxy dark matter halos using a high resolution LCDM N-body simulation. Our merger trees follow ~17,000 halos with masses M_0 = (10^11--10^13) Msun at z=0 and track accretion events involving objects as small as m = 10^10 Msun. We find that mass assembly is remarkably self-similar in m/M_0, and dominated by mergers that are ~10% of the final halo mass. While very large mergers, m > 0.4 M_0, are quite rare, sizeable accretion events, m ~ 0.1 M_0, are common. Over the last 10 Gyr, an overwhelming majority (~95%) of Milky Way-sized halos with M_0 = 10^12 Msun have accreted at least one object with greater total mass than the Milky Way disk (m > 5x10^10 Msun), and approximately 70% have accreted an object with more than twice that mass (m > 10^11 Msun). Our results raise serious concerns about the survival of thin-disk dominated galaxies within the current paradigm for galaxy formation in a CDM universe. In order to achieve a ~70% disk-dominated fraction in Milky Way-sized CDM halos, mergers involving m ~ 2x10^11 Msun objects must not destroy disks. Considering that most thick disks and bulges contain old stellar populations, the situation is even more restrictive: these mergers must not heat disks or drive gas into their centers to create young bulges.

Kyle R. Stewart; James S. Bullock; Risa H. Wechsler; Ariyeh H. Maller; Andrew R. Zentner

2007-11-30T23:59:59.000Z

294

Spin-Induced Disk Precession in Sagittarius A*  

E-Print Network (OSTI)

In Sgr A* at the Galactic center, by far the closest and easiest supermassive black hole we can study, the observational evidence is increasingly pointing to the presence of a compact, hot, magnetized disk feeding the accretor. In such low-Mach-number plasmas, forces arising, e.g., from pressure gradients in the plasma, can altogether negate the warping of disks around Kerr black holes caused by the Bardeen-Petterson effect and can lead to coherent precession of the entire disk. In this Letter, we present for the first time highly detailed 3D SPH simulations of the accretion disk evolution in Sgr A*, guided by observational constraints on its physical characteristics, and conclude that indeed the Bardeen-Petterson effect is probably absent in this source. Given what we now understand regarding the emission geometry in this object, we suggest that a ~ 50-500-day modulation in Sgr A*'s spectrum, arising from the disk precession, could be an important observational signature; perhaps the ~ 106-day period seen earlier in its radio flux, if confirmed, could be due to this process. On the other hand, if future observations do not confirm this long modulation in Sgr A*'s spectrum, this would be an indication that either the disk size or orientation is very different from current estimates, or that the black hole is not spinning at all (unlikely), or that our current understanding of how it produces its radiative output is incorrect.

Gabriel Rockefeller; Christopher L. Fryer; Fulvio Melia

2005-08-03T23:59:59.000Z

295

Moving-boundary approximation for curved streamer ionization fronts: Numerical tests  

Science Journals Connector (OSTI)

Recently a moving boundary approximation for the minimal model for negative streamer ionization fronts was extended with effects due to front curvature; this was done through a systematic solvability analysis. A central prediction of this analysis is the existence of a nonvanishing electric field in the streamer interior, whose value is proportional to the front curvature. In this paper we compare this result and other predictions of the solvability analysis with numerical simulations of the minimal model.

Fabian Brau, Alejandro Luque, Benny Davidovitch, and Ute Ebert

2009-06-26T23:59:59.000Z

296

Activation, Heating and Exposure Rates for Mo?99 Experiments with 25?Disk Targets  

SciTech Connect

An MCNPX model of the 25-disk target assembly inside the vacuum cube inside the shielded box was prepared. This was used to calculate heating and photon and neutron fluxes throughout the model. Production rates for photonuclear reaction products were calculated using the photon fluxes and ENDF/B-VII cross sections. Measured isomer to ground state yield ratios were used where available. Where not available the new correlation between spin deficit and isomer to ground state yield ratios presented at AccApp'11 was used. The photonuclear production rates and neutron fluxes were input to CINDER2008 for transmutation calculations. A cross section update file was used to supply (n,n') reactions missing from CINDER2008 libraries. Decay photon spectra produced by CINDER2008 were then used to calculate exposure rates using the MCNPX model. Two electron beam irradiations were evaluated. The first was for a thermal test at 15 MeV with 1300 {micro}A incident on one target end and the second was for a production test at 35 MeV with 350 {micro}A incident on both target ends (700 {micro}A total current on target). For the thermal test 1, 2, 3, 4, 5 and 6 h irradiation times were simulated, each followed by decay time steps out to 42 days. For the production test 6, 12, 18, 24, 30 and 36 h irradiation times were simulated followed by the same decay periods. For all simulations beam FWHMs in x and y were both assumed to be 6 mm. Simulations were run for Mo-100 enriched and natural Mo targets for both tests. It is planned that thermal test will be run for 4 h with natural target disks and production test will be run for 24 h with enriched target disks. Results for these two simulations only are presented in this report. Other results can be made available upon request. Post irradiation exposure rates were calculated at 30 cm distances from left, right, front and back of the following configurations: (1) Shielded box with everything in it (beam pipes, cooling pipes, vacuum cube, target housing weldment and target assembly), (2) Shielded box with everything in it except the target assembly, (3) Shielded box with nothing in it, (4) Target assembly taken outside of shielded box, (5) Target disks in cradle (target assembly with thermocouple weldment and flange removed), (6) Empty cradle, and (7) Target disks alone. Decay photon spectra from the CINDER2008 calculations were used as sources for the exposure rate calculations in the same model used for the flux calculations with beam on. As components were removed to simulate the seven cases considered the material compositions were changed to air and their respective sources were turned off. The MCNPX model geometry is plotted in Figure 1. The left and right detector locations for cases 1, 2 and 3 were 30 cm from the shielded box walls and 30 cm from the beam pipe openings in the left and right sides of the model (they are not in the beam line). A zoomed in plot of the target assembly alone is in Figure 2. Exposure rates for the seven cases are plotted as a function of time after irradiation in Figures 3, 4 and 5. To aid in comparison between the cases, all of these figures have been plotted using the same scale. Figures 3 and 4 are respectively the thermal and production test results for cases 1 through 6. Figure 5 includes case 7 results for both. Differences between cases 1 and 2 for both tests are not statistically significant showing that activation of components other than the target assembly, many of which are also shielding the target assembly, dominates exposure rates outside the shielded box. Case 3 shows the contribution from activation of the shield box itself. In front where shielded box wall is thickest box activation accounts for essentially all of the exposure rate outside. Differences between cases 4 and 5 are also minimal, showing that the contribution to target assembly exposure rates from the thermocouple flange and weldment are small compared to the target disks and cradle. From the numerical results the contribution is about 1%. Results for case 6, the cradle itself, are ini

Kelsey, Charles T. IV [Los Alamos National Laboratory

2012-05-09T23:59:59.000Z

297

E-Print Network 3.0 - automobile front panel Sample Search Results  

NLE Websites -- All DOE Office Websites (Extended Search)

Search Powered by Explorit Topic List Advanced Search Sample search results for: automobile front panel Page: << < 1 2 3 4 5 > >> 1 FUTURES OF AUTOMOBILE INDUSTRY AND...

298

Infinite Nuclear Matter on the Light Front: A Modern Approach to Brueckner Theory  

E-Print Network (OSTI)

Understanding an important class of experiments requires that light-front dynamics and related light cone variables k^+ and k_perp be used. If one uses k^+ as a momentum variable, the corresponding canonical spatial variable is x^-=x^0-x^3 and the time variable is x^0+x^3. This is the light front (LF) approach of Dirac. A relativistic light front formulation of nuclear dynamics is developed and applied to treating infinite nuclear matter in a method which includes the corelations of pairs of nculeons. This is light front Brueckner theory.

G. A. Miller

1999-10-19T23:59:59.000Z

299

Failure Analysis of Cap Screws in a Diesel Engine Front Gear Train  

Science Journals Connector (OSTI)

Two failures of the front gear train cap screws of a diesel engine in a marine vessel are investigated. Fractured cap screws were...

E. W. Jones; R. S. Florea; D. K. Francis

2013-08-01T23:59:59.000Z

300

Evaluating the effects of wildfire on stream processes in a Colorado front range watershed, USA  

Science Journals Connector (OSTI)

The impacts of a September 2010 wildfire on hydrologic and biogeochemical processes are being evaluated in a Colorado Front Range stream.

Sheila F. Murphy; Jeffrey H. Writer

2011-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "brakes front disk" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


301

Pion light-front wave function, parton distribution and the electromagnetic form factor  

E-Print Network (OSTI)

We derive a light-front wave function of the pion, which reproduces its valence parton distribution and a electromagnetic form factor consistent with data.

Thomas Gutsche; Valery E. Lyubovitskij; Ivan Schmidt; Alfredo Vega

2014-10-23T23:59:59.000Z

302

The speed of propagation of fronts for the reactiondiffusion ...  

E-Print Network (OSTI)

About a decade ago, in collaboration with M. Cristina Depassier we proved a variational characterization of the speed of propagation of fronts for rather general...

2007-05-18T23:59:59.000Z

303

Disks, young stars, and radio waves: the quest for forming planetary systems  

E-Print Network (OSTI)

Kant and Laplace suggested the Solar System formed from a rotating gaseous disk in the 18th century, but convincing evidence that young stars are indeed surrounded by such disks was not presented for another 200 years. As we move into the 21st century the emphasis is now on disk formation, the role of disks in star formation, and on how planets form in those disks. Radio wavelengths play a key role in these studies, currently providing some of the highest spatial resolution images of disks, along with evidence of the growth of dust grains into planetesimals. The future capabilities of EVLA and ALMA provide extremely exciting prospects for resolving disk structure and kinematics, studying disk chemistry, directly detecting proto-planets, and imaging disks in formation.

Claire J. Chandler; Debra S. Shepherd

2008-01-24T23:59:59.000Z

304

A SEMI-ANALYTICAL DESCRIPTION FOR THE FORMATION AND GRAVITATIONAL EVOLUTION OF PROTOPLANETARY DISKS  

SciTech Connect

We investigate the formation process of self-gravitating protoplanetary disks in unmagnetized molecular clouds. The angular momentum is redistributed by the action of gravitational torques in the massive disk during its early formation. We develop a simplified one-dimensional accretion disk model that takes into account the infall of gas from the envelope onto the disk and the transfer of angular momentum in the disk with an effective viscosity. First we evaluate the gas accretion rate from the cloud core onto the disk by approximately estimating the effects of gas pressure and gravity acting on the cloud core. We formulate the effective viscosity as a function of the Toomre Q parameter that measures the local gravitational stability of the rotating thin disk. We use a function for viscosity that changes sensitively with Q when the disk is gravitationally unstable. We find a strong self-regulation mechanism in the disk evolution. During the formation stage of protoplanetary disks, the evolution of the surface density does not depend on the other details of the modeling of effective viscosity, such as the prefactor of the viscosity coefficient. Next, to verify our model, we compare the time evolution of the disk calculated with our formulation with that of three-dimensional hydrodynamical simulations. The structures of the resultant disks from the one-dimensional accretion disk model agree well with those of the three-dimensional simulations. Our model is a useful tool for the further modeling of chemistry, radiative transfer, and planet formation in protoplanetary disks.

Takahashi, Sanemichi Z.; Inutsuka, Shu-ichiro [Department of Physics, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi, 464-8602 (Japan); Machida, Masahiro N., E-mail: takahashi.sanemichi@a.mbox.nagoya-u.ac.jp, E-mail: inutsuka@nagoya-u.jp, E-mail: sanemichi@tap.scphys.kyoto-u.ac.jp, E-mail: machida.masahiro.018@m.kyushu-u.ac.jp [Department of Earth and Planetary Science, Kyushu University, Higashi-ku, Fukuoka 812-8581 (Japan)

2013-06-10T23:59:59.000Z

305

MAGNETOROTATIONAL-INSTABILITY-DRIVEN ACCRETION IN PROTOPLANETARY DISKS  

SciTech Connect

Non-ideal MHD effects play an important role in the gas dynamics in protoplanetary disks (PPDs). This paper addresses the influence of non-ideal MHD effects on the magnetorotational instability (MRI) and angular momentum transport in PPDs using the most up-to-date results from numerical simulations. We perform chemistry calculations using a complex reaction network with standard prescriptions for X-ray and cosmic-ray ionizations. We first show that whether or not grains are included, the recombination time is at least one order of magnitude less than the orbital time within five disk scale heights, justifying the validity of local ionization equilibrium and strong coupling limit in PPDs. The full conductivity tensor at different disk radii and heights is evaluated, with the MRI active region determined by requiring that (1) the Ohmic Elsasser number {Lambda} be greater than 1 and (2) the ratio of gas to magnetic pressure {beta} be greater than {beta}{sub min}(Am) as identified in the recent study by Bai and Stone, where Am is the Elsasser number for ambipolar diffusion. With full flexibility as to the magnetic field strength, we provide a general framework for estimating the MRI-driven accretion rate M-dot and the magnetic field strength in the MRI active layer. We find that the MRI active layer always exists at any disk radius as long as the magnetic field in PPDs is sufficiently weak. However, the optimistically predicted M-dot in the inner disk (r = 1-10 AU) appears insufficient to account for the observed range of accretion rates in PPDs (around 10{sup -8} M{sub sun} yr{sup -1}) even in the grain-free calculation, and the presence of solar abundance sub-micron grains further reduces M-dot by one to two orders of magnitude. Moreover, we find that the predicted M-dot increases with radius in the inner disk where accretion is layered, which would lead to runaway mass accumulation if disk accretion is solely driven by the MRI. Our results suggest that stronger sources of ionization and/or additional mechanisms such as magnetized wind are needed to explain the observed accretion rates in PPDs. In contrast, our predicted M-dot is on the order of 10{sup -9} M{sub sun} yr{sup -1} in the outer disk, consistent with the observed accretion rates in transitional disks.

Bai Xuening, E-mail: xbai@astro.princeton.edu [Department of Astrophysical Sciences, Princeton University, Princeton, NJ 08544 (United States)

2011-09-20T23:59:59.000Z

306

Giant disk galaxies : Where environment trumps mass in galaxy evolution  

E-Print Network (OSTI)

We identify some of the most HI massive and fastest rotating disk galaxies in the local universe with the aim of probing the processes that drive the formation of these extreme disk galaxies. By combining data from the Cosmic Flows project, which has consistently reanalyzed archival galaxy HI profiles, and 3.6$\\mu$m photometry obtained with the Spitzer Space Telescope, with which we can measure stellar mass, we use the baryonic Tully-Fisher (BTF) relationship to explore whether these massive galaxies are distinct. We discuss several results, but the most striking is the systematic offset of the HI-massive sample above the BTF. These galaxies have both more gas and more stars in their disks than the typical disk galaxy of similar rotational velocity. The "condensed" baryon fraction, $f_C$, the fraction of the baryons in a dark matter halo that settle either as cold gas or stars into the disk, is twice as high in the HI-massive sample than typical, and almost reaches the universal baryon fraction in some cases,...

Courtois, H M; Sorce, J G; Pomarede, D

2015-01-01T23:59:59.000Z

307

Non-LTE modeling of supernova-fallback disks  

E-Print Network (OSTI)

We present a first detailed spectrum synthesis calculation of a supernova-fallback disk composed of iron. We assume a geometrically thin disk with a radial structure described by the classical alpha-disk model. The disk is represented by concentric rings radiating as plane-parallel slabs. The vertical structure and emission spectrum of each ring is computed in a fully self-consistent manner by solving the structure equations simultaneously with the radiation transfer equations under non-LTE conditions. We describe the properties of a specific disk model and discuss various effects on the emergent UV/optical spectrum. We find that strong iron-line blanketing causes broad absorption features over the whole spectral range. Limb darkening changes the spectral distribution up to a factor of four depending on the inclination angle. Consequently, such differences also occur between a blackbody spectrum and our model. The overall spectral shape is independent of the exact chemical composition as long as iron is the dominant species. A pure iron composition cannot be distinguished from silicon-burning ash. Non-LTE effects are small and restricted to few spectral features.

K. Werner; T. Nagel; T. Rauch

2006-08-24T23:59:59.000Z

308

Chemistry and line emission from evolving Herbig Ae disks  

E-Print Network (OSTI)

Aims: To calculate chemistry and gas temperature of evolving protoplanetary disks with decreasing mass or dust settling, and to explore the sensitivity of gas-phase tracers. Methods: The density and dust temperature profiles for a range of models of flaring and self-shadowed disks around a typical Herbig Ae star are used together with 2-dimensional ultraviolet (UV) radiative transfer to calculate the chemistry and gas temperature. In each model the line profiles and intensities for the fine structure lines of [O I], [C II] and [C I] and the pure rotational lines of CO, CN, HCN and HCO+ are determined. Results: The chemistry shows a strong correlation with disk mass. Molecules that are easily dissociated, like HCN, require high densities and large extinctions before they can become abundant. The products of photodissociation, like CN and C2H, become abundant in models with lower masses. Dust settling mainly affects the gas temperature, and thus high temperature tracers like the O and C+ fine structure lines. The carbon chemistry is found to be very sensitive to the adopted PAH abundance. The line ratios CO/13CO, CO/HCO+ and [O I] 63 um/146 um can be used to distinguish between disks where dust growth and settling takes place, and disks that undergo overall mass loss.

B. Jonkheid; C. P. Dullemond; M. R. Hogerheijde; E. F. van Dishoeck

2006-11-07T23:59:59.000Z

309

RELAXATION OF WARPED DISKS: THE CASE OF PURE HYDRODYNAMICS  

SciTech Connect

Orbiting disks may exhibit bends due to a misalignment between the angular momentum of the inner and outer regions of the disk. We begin a systematic simulational inquiry into the physics of warped disks with the simplest case: the relaxation of an unforced warp under pure fluid dynamics, i.e., with no internal stresses other than Reynolds stress. We focus on the nonlinear regime in which the bend rate is large compared to the disk aspect ratio. When warps are nonlinear, strong radial pressure gradients drive transonic radial motions along the disk's top and bottom surfaces that efficiently mix angular momentum. The resulting nonlinear decay rate of the warp increases with the warp rate and the warp width, but, at least in the parameter regime studied here, is independent of the sound speed. The characteristic magnitude of the associated angular momentum fluxes likewise increases with both the local warp rate and the radial range over which the warp extends; it also increases with increasing sound speed, but more slowly than linearly. The angular momentum fluxes respond to the warp rate after a delay that scales with the square root of the time for sound waves to cross the radial extent of the warp. These behaviors are at variance with a number of the assumptions commonly used in analytic models to describe linear warp dynamics.

Sorathia, Kareem A.; Krolik, Julian H. [Department of Physics and Astronomy, Johns Hopkins University, Baltimore, MD 21218 (United States); Hawley, John F. [Department of Astronomy, University of Virginia, Charlottesville, VA 22904 (United States)

2013-05-10T23:59:59.000Z

310

IMA Journal of Applied Mathematics (2002) 67, 419439 Modelling thermal front dynamics in microwave heating  

E-Print Network (OSTI)

an electric field is applied to materials with high resistivity, the dipole moments of the molecules alignIMA Journal of Applied Mathematics (2002) 67, 419­439 Modelling thermal front dynamics in microwave July 2000; revised on 6 December 2001] The formation and propagation of thermal fronts in a cylindrical

Xin, Jack

311

Conditional Simulation of a Gust-Front Wind Field Lijuan Wanga  

E-Print Network (OSTI)

Conditional Simulation of a Gust-Front Wind Field Lijuan Wanga , Ahsan Kareema a NatHaz Modeling the conditional simulation of gust-front wind velocities are presented to generate time series at locations effects on structures, the simulation of wind velocity conditional upon the availability of measured

Kareem, Ahsan

312

Silicon Solar Cells with Front Hetero-contact and Aluminum Alloy Back Junction (Poster)  

SciTech Connect

The objectives of this report are: (1) to apply industrial back Al process in efficient n-wafer cells with a-Si:H front surface passivation; and (2) to evaluate the surface recombination velocity (SRV) of the a-Si:H passivated front surface with different surface preparation procedures.

Yuan, H.-C.; Page, M. R.; Iwaniczko, E.; Xu, Y.; Roybal, L.; Wang, Q.; Branz, H. M.; Meier, D. L.

2008-05-01T23:59:59.000Z

313

Asymmetry of Columbia River tidal plume fronts David A. Jay a,  

E-Print Network (OSTI)

or northern side and mark a transition from supercritical to subcritical flow for up to 12 h after high water plume water mass. This vorticitycontrols the transition of the tidal plume front to a subcritical state plume may overlie newly upwelled waters, these fronts can mix nutrients into the plume. Symmetry would

Hickey, Barbara

314

CISC 327 -Fall 2014 ! Course Project Assignment #1 -Front End Requirements!  

E-Print Network (OSTI)

represent those requirements as a set of requirements tests. The basic idea is to analyze the requirements, and create a test case for each piece. We will study this more in class.! !Create and organize a complete set of requirements tests for the Front End of Quinterac, to test for every required behaviour (of the Front End only

Cordy, James R.

315

Nitrogen Front Evolution in Purged Polymer Electrolyte Membrane Fuel Cell with Dead-Ended Anode  

E-Print Network (OSTI)

Nitrogen Front Evolution in Purged Polymer Electrolyte Membrane Fuel Cell with Dead-Ended Anode and experimentally verify the evolution of liquid water and nitrogen fronts along the length of the anode channel in a proton exchange membrane fuel cell operating with a dead-ended anode that is fed by dry hydrogen

Stefanopoulou, Anna

316

Air-sea interaction at an oceanic front: Implications for frontogenesis and primary production  

E-Print Network (OSTI)

Air-sea interaction at an oceanic front: Implications for frontogenesis and primary production Dake a significant air-sea interaction at the shelf- break front in the East China Sea. An idealized ocean was identified in the model and its consequences were evaluated. We found that air-sea interaction, when combined

Chen, .Dake

317

A Review of Cold Fronts with Prefrontal Troughs and Wind Shifts DAVID M. SCHULTZ  

E-Print Network (OSTI)

A Review of Cold Fronts with Prefrontal Troughs and Wind Shifts DAVID M. SCHULTZ Cooperative with a pressure trough and a distinct wind shift at the surface. Many cold fronts, however, do not conform to this model--time series at a single surface station may possess a pressure trough and wind shift in the warm

Schultz, David

318

Traveling Fronts of Copper Deposition Stephanie Thouvenel-Romans, Konstantin Agladze, and Oliver Steinbock*  

E-Print Network (OSTI)

Traveling Fronts of Copper Deposition Stephanie Thouvenel-Romans, Konstantin Agladze, and Oliver for propagating fronts that mediate the electroless deposition of copper on passivated steel. Under ap- propriate is essentially independent from the copper(II) concentration in the electrolyte, which indicates

Steinbock, Oliver

319

The Interruption of Alpine Foehn by a Cold Front. Part I: Observations  

E-Print Network (OSTI)

propagation speed wf 1 m/s Inclination of the frontal surface is wf /uf 1/7.5 8° Freitag (1990 in valleys Interaction with local winds (e.g., foehn) foehn cold front Cold front in complex terrain ? ? #12 in Inn and Wipp Valley Temperature slope profile Doppler wind lidar in Wipp Valley #12;6 of 13 Case study

Gohm, Alexander

320

The Life Cycle of an Undular Bore and Its Interaction with a Shallow, Intense Cold Front  

E-Print Network (OSTI)

of the horizontal wind and a local minimum in surface pressure. Despite the conceptual appeal of the classical model of an undular bore and its associated wind shift, spawned by the passage of a shallow surface cold front over the wind shift and thermodynamic properties of the front was induced by the formation of a bore over south

Williams, Justin

Note: This page contains sample records for the topic "brakes front disk" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


321

PHYSICS RESULTS OF THE NSLS-II LINAC FRONT END TEST STAND  

SciTech Connect

The Linac Front End Test Stand (LFETS) was installed at the Source Development Laboratory (SDL) in the fall of 2011 in order to test the Linac Front End. The goal of these tests was to test the electron source against the specifications of the linac. In this report, we discuss the results of these measurements and the effect on linac performance.

Fliller R. P.; Gao, F.; Yang, X.; Rose, J.; Shaftan, T.; Piel, C

2012-05-20T23:59:59.000Z

322

Mineral paragenesis and textures associated with sandstone-hosted roll-front uranium deposits, NW China  

E-Print Network (OSTI)

, People's Republic of China c Northwest Institute of Uranium Geology, China National Nuclear CorporationMineral paragenesis and textures associated with sandstone-hosted roll-front uranium deposits, NW, Wuyiyi and Shihongtan sandstone-hosted roll-front uranium deposits, northwest China. The mineralization

Fayek, Mostafa

323

Evidence of uranium biomineralization in sandstone-hosted roll-front uranium deposits, northwestern China  

E-Print Network (OSTI)

Evidence of uranium biomineralization in sandstone-hosted roll-front uranium deposits, northwestern Available online 25 January 2005 Abstract We show evidence that the primary uranium minerals, uraninite-front uranium deposits, Xinjiang, northwestern China were biogenically precipitated and psuedomorphically

Fayek, Mostafa

324

COLD FRONTS AND GAS SLOSHING IN GALAXY CLUSTERS WITH ANISOTROPIC THERMAL CONDUCTION  

SciTech Connect

Cold fronts in cluster cool cores should be erased on short timescales by thermal conduction, unless protected by magnetic fields that are 'draped' parallel to the front surfaces, suppressing conduction perpendicular to the sloshing fronts. We present a series of MHD simulations of cold front formation in the core of a galaxy cluster with anisotropic thermal conduction, exploring a parameter space of conduction strengths parallel and perpendicular to the field lines. Including conduction has a strong effect on the temperature distribution of the core and the appearance of the cold fronts. Though magnetic field lines are draping parallel to the front surfaces, preventing conduction directly across them, the temperature jumps across the fronts are nevertheless reduced. The geometry of the field is such that the cold gas below the front surfaces can be connected to hotter regions outside via field lines along directions perpendicular to the plane of the sloshing motions and along sections of the front that are not perfectly draped. This results in the heating of this gas below the front on a timescale of a Gyr, but the sharpness of the density and temperature jumps may nevertheless be preserved. By modifying the gas density distribution below the front, conduction may indirectly aid in suppressing Kelvin-Helmholtz instabilities. If conduction along the field lines is unsuppressed, we find that the characteristic sharp jumps seen in Chandra observations of cold front clusters do not form. Therefore, the presence of cold fronts in hot clusters is in contradiction with our simulations with full Spitzer conduction. This suggests that the presence of cold fronts in hot clusters could be used to place upper limits on conduction in the bulk of the intracluster medium. Finally, the combination of sloshing and anisotropic thermal conduction can result in a larger flux of heat to the core than either process in isolation. While still not sufficient to prevent a cooling catastrophe in the very central (r {approx} 5 kpc) regions of the cool core (where something else is required, such as active galactic nucleus feedback), it reduces significantly the mass of gas that experiences a cooling catastrophe outside those small radii.

ZuHone, J. A.; Markevitch, M. [Astrophysics Science Division, Laboratory for High Energy Astrophysics, Code 662, NASA/Goddard Space Flight Center, Greenbelt, MD 20771 (United States)] [Astrophysics Science Division, Laboratory for High Energy Astrophysics, Code 662, NASA/Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Ruszkowski, M. [Department of Astronomy, University of Michigan, 500 Church Street, Ann Arbor, MI 48109 (United States)] [Department of Astronomy, University of Michigan, 500 Church Street, Ann Arbor, MI 48109 (United States); Lee, D. [The Flash Center for Computational Science, The University of Chicago, 5747 S. Ellis, Chicago, IL 60637 (United States)] [The Flash Center for Computational Science, The University of Chicago, 5747 S. Ellis, Chicago, IL 60637 (United States)

2013-01-10T23:59:59.000Z

325

PROTOSTELLAR DISK FORMATION ENABLED BY WEAK, MISALIGNED MAGNETIC FIELDS  

SciTech Connect

The gas from which stars form is magnetized, and strong magnetic fields can efficiently transport angular momentum. Most theoretical models of this phenomenon find that it should prevent formation of large (>100 AU), rotationally supported disks around most protostars, even when non-ideal magnetohydrodynamic (MHD) effects that allow the field and gas to decouple are taken into account. Using recent observations of magnetic field strengths and orientations in protostellar cores, we show that this conclusion is incorrect. The distribution of magnetic field strengths is very broad, and alignments between fields and angular momentum vectors within protostellar cores are essentially random. By combining the field strength and misalignment data with MHD simulations showing that disk formation is expected for both weak and misaligned fields, we show that these observations imply that we should expect disk fractions of {approx}10%-50% even when protostars are still deeply embedded in their parent cores, and even if the gas is governed by ideal MHD.

Krumholz, Mark R. [Department of Astronomy and Astrophysics, University of California, Santa Cruz, CA 95064 (United States); Crutcher, Richard M. [Department of Astronomy, University of Illinois at Urbana-Champaign, 1002 W Green Street, Urbana, IL 61801 (United States); Hull, Charles L. H., E-mail: mkrumhol@ucsc.edu [Astronomy Department and Radio Astronomy Laboratory, University of California, Berkeley, CA 94720-3411 (United States)

2013-04-10T23:59:59.000Z

326

A gaseous metal disk around a white dwarf  

E-Print Network (OSTI)

The destiny of planetary systems through the late evolution of their host stars is very uncertain. We report a metal-rich gas disk around a moderately hot and young white dwarf. A dynamical model of the double-peaked emission lines constrains the outer disk radius to just 1.2 solar radii. The likely origin of the disk is a tidally disrupted asteroid, which has been destabilised from its initial orbit at a distance of more than 1000 solar radii by the interaction with a relatively massive planetesimal object or a planet. The white dwarf mass of 0.77 solar masses implies that planetary systems may form around high-mass stars.

B. T. Gaensicke; T. R. Marsh; J. Southworth; A. Rebassa-Mansergas

2006-12-22T23:59:59.000Z

327

Debris Disks Around White Dwarfs: The DAZ Connection  

E-Print Network (OSTI)

We present near-infrared spectroscopic observations of 20 previously known DAZ white dwarfs obtained at the NASA Infrared Telescope Facility. Two of these white dwarfs (G29-38 and GD362) are known to display significant K-band excesses due to circumstellar debris disks. Here we report the discovery of excess K-band radiation from another DAZ white dwarf, WD0408-041 (GD56). Using spectroscopic observations, we show that the excess radiation cannot be explained by a stellar or substellar companion, and is likely to be caused by a warm debris disk. Our observations strengthen the connection between the debris disk phenomena and the observed metal abundances in cool DAZ white dwarfs. However, we do not find any excess infrared emission from the most metal rich DAZs with $T_{\\rm eff}=$ 16000 -- 20000 K. This suggests that the metal abundances in warmer DAZ white dwarfs may require another explanation.

Mukremin Kilic; Ted von Hippel; S. K. Leggett; D. E. Winget

2006-03-28T23:59:59.000Z

328

Low-mass planets in nearly inviscid disks: Numerical treatment  

E-Print Network (OSTI)

Embedded planets disturb the density structure of the ambient disk and gravitational back-reaction will induce possibly a change in the planet's orbital elements. The accurate determination of the forces acting on the planet requires careful numerical analysis. Recently, the validity of the often used fast orbital advection algorithm (FARGO) has been put into question, and special numerical resolution and stability requirements have been suggested. In this paper we study the process of planet-disk interaction for small mass planets of a few Earth masses, and reanalyze the numerical requirements to obtain converged and stable results. One focus lies on the applicability of the FARGO-algorithm. Additionally, we study the difference of two and three-dimensional simulations, compare global with local setups, as well as isothermal and adiabatic conditions. We study the influence of the planet on the disk through two- and three-dimensional hydrodynamical simulations. To strengthen our conclusions we perform a detai...

Kley, Wilhelm; Kolb, Stefan M; Benitez-Llambay, Pablo; Masset, Frederic

2012-01-01T23:59:59.000Z

329

Interferometric Detection of Planets/Gaps in Protoplanetary Disks  

E-Print Network (OSTI)

We investigate the possibility to find evidence for planets in circumstellar disks by infrared and submillimeter interferometry. Hydrodynamical simulations of a circumstellar disk around a solar-type star with an embedded planet of 1 Jupiter mass are presented. On the basis of 3D radiative transfer simulations, images of this system are calculated. These intensity maps provide the basis for the simulation of the interferometers VLTI (equipped with the mid-infrared instrument MIDI) and ALMA. While ALMA will provide the necessary basis for a direct gap and therefore indirect planet detection, MIDI/VLTI will provide the possibility to distinguish between disks with or without accretion on the central star on the basis of visibility measurements.

S. Wolf; F. Gueth; Th. Henning; W. Kley

2002-08-26T23:59:59.000Z

330

Does Dissipation in AGN Disks Couple to the Total Pressure?  

E-Print Network (OSTI)

Recent work on the transport of angular momentum in accretion disks suggests that the Velikhov-Chandrasekhar instability, in which a large scale magnetic field generates small scale eddys in a shearing environment, may be ultimately responsible for this process. Although there is considerable controversy about the origin and maintenance of this field in accretion disks, it turns out that it is possible to argue, quite generally, using scaling arguments, that this process is sensitive to the total pressure in an AGN disk, rather than the pressure contributed by gas alone. We conclude that the resolution of the conceptual difficulties implied by the presence of strong thermal and viscous instabilities in radiation pressure and electron scattering dominated does not lie in models that couple the total dissipation rate to the gas pressure alone, or to some weighted mean of the gas and radiation pressures.

E. T. Vishniac

1993-08-12T23:59:59.000Z

331

Spectral modeling of gaseous metal disks around DAZ white dwarfs  

E-Print Network (OSTI)

We report on our attempt for the first non-LTE modeling of gaseous metal disks around single DAZ white dwarfs recently discovered by Gaensicke et al. and thought to originate from a disrupted asteroid. We assume a Keplerian rotating viscous disk ring composed of calcium and hydrogen and compute the detailed vertical structure and emergent spectrum. We find that the observed infrared CaII emission triplet can be modeled with a hydrogen-deficient gas ring located at R=1.2 R_sun, inside of the tidal disruption radius, with Teff about 6000 K and a low surface mass density of about 0.3 g/cm**2. A disk having this density and reaching from the central white dwarf out to R=1.2 R_sun would have a total mass of 7 10**21 g, corresponding to an asteroid with about 160 km diameter.

K. Werner; T. Nagel; T. Rauch

2008-09-30T23:59:59.000Z

332

Testing protostellar disk formation models with ALMA observations  

E-Print Network (OSTI)

Abridged: Recent simulations have explored different ways to form accretion disks around low-mass stars. We aim to present observables to differentiate a rotationally supported disk from an infalling rotating envelope toward deeply embedded young stellar objects and infer their masses and sizes. Two 3D magnetohydrodynamics (MHD) formation simulations and 2D semi-analytical model are studied. The dust temperature structure is determined through continuum radiative transfer RADMC3D modelling. A simple temperature dependent CO abundance structure is adopted and synthetic spectrally resolved submm rotational molecular lines up to $J_{\\rm u} = 10$ are simulated. All models predict similar compact components in continuum if observed at the spatial resolutions of 0.5-1$"$ (70-140 AU) typical of the observations to date. A spatial resolution of $\\sim$14 AU and high dynamic range ($> 1000$) are required to differentiate between RSD and pseudo-disk in the continuum. The peak-position velocity diagrams indicate that the...

Harsono, Daniel; Bruderer, Simon; Li, Zhi-Yun; Jorgensen, Jes

2015-01-01T23:59:59.000Z

333

Disk Space Quota Management | Argonne Leadership Computing Facility  

NLE Websites -- All DOE Office Websites (Extended Search)

Account Information Accounts and Access FAQ Connect & Log In Using CRYPTOCards SSH Keys on Surveyor Disk Space Quota Management Allocations Decommissioning of BG/P Systems and Resources Blue Gene/Q Versus Blue Gene/P Mira/Cetus/Vesta Intrepid/Challenger/Surveyor Tukey Eureka / Gadzooks Policies Documentation Feedback Please provide feedback to help guide us as we continue to build documentation for our new computing resource. [Feedback Form] Disk Space Quota Management As you manage your project's disk space quota, it's important to remember that users you approve as to be added as project members are also added to the project's Unix Group. Unix Group members have the ability to write to the project directory and to access project data. You can manually add or remove Unix

334

Hall-effect Controlled Gas Dynamics in Protoplanetary Disks: II. Full 3D Simulations toward the Outer Disk  

E-Print Network (OSTI)

We perform 3D stratified shearing-box MHD simulations on the gas dynamics of protoplanetary disks threaded by net vertical magnetic field Bz. All three non-ideal MHD effects, Ohmic resistivity, the Hall effect and ambipolar diffusion are included in a self-consistent manner based on equilibrium chemistry. We focus on regions toward outer disk radii, from 5-60AU, where Ohmic resistivity tends to become negligible, ambipolar diffusion dominates over an extended region across disk height, and the Hall effect largely controls the dynamics near the disk midplane. We find that around R=5AU, the system launches a laminar/weakly turbulent magnetocentrifugal wind when the net vertical field Bz is not too weak, as expected. Moreover, the wind is able to achieve and maintain a configuration with reflection symmetry at disk midplane. The case with anti-aligned field polarity (Omega. Bz<0) is more susceptible to the MRI when Bz drops, leading to an outflow oscillating in radial directions and very inefficient angular m...

Bai, Xue-Ning

2014-01-01T23:59:59.000Z

335

GLLH EM Invisible Cloak With Novel Front Branching And Without Exceed Light Speed Violation  

E-Print Network (OSTI)

In this paper, we propose new Global and Local (GL) electromagnetic (EM) cloaks with distinctive class material a_{\\alpha \\beta}\\log ^\\alpha (b_{\\alpha \\beta}/h) h^\\beta (GLLH Cloak) without exceed light speed violation. The refractive index of the GLLH cloak material, $n(r)$, is large than one or equal to one. Our GLLH cloak is created by GL EM modeling and GL EM cloak inversion with searching class \\it a_{\\alpha \\beta}\\log ^\\alpha (b_{\\alpha \\beta}/h) h^\\beta. The GLLH cloaks in this paper have finite speed and have no exceed light speed? physical violations and have more advantages. The GLLH EM cloaks can be practicable by using normal materials and are available for all broad frequency band. The GL EM cloak inversion and electromagnetic integral equation for cloak are presented in this paper. The novel EM wave propagation and front branching in the GLLH cloak by GL EM modeling are presented in this paper. The EM wave front propagation in GLLH cloak is behind of the front in free space. At time steps $118 dt$, in the GLLH cloak, the wave front is curved as a crescent like and propagates slower than the light in free space. At the time step $119dt$, the EM wave inside of the GLLH cloak propagates slower than light speed, moreover, its two crescent front peaks intersect at a front branching point. At the front branching point, the front is split to two fronts. The novel front branching and crescent like wave propagation are displayed in the following figure 1, figure 2 and figures 5 -20 in this paper. All copyright and patent of the GLLH EM cloaks and GL modeling and inversion methods are reserved by authors in GL Geophysical Laboratory.

Ganquan Xie; Jianhua Li; Lee Xie; Feng Xie

2010-05-21T23:59:59.000Z

336

EFFECTS OF LOCAL DISSIPATION PROFILES ON MAGNETIZED ACCRETION DISK SPECTRA  

SciTech Connect

We present spectral calculations of non-LTE accretion disk models appropriate for high-luminosity stellar mass black hole X-ray binary systems. We first use a dissipation profile based on scaling the results of shearing box simulations of Hirose et al. to a range of annuli parameters. We simultaneously scale the effective temperature, orbital frequency, and surface density with luminosity and radius according to the standard {alpha}-model. This naturally brings increased dissipation to the disk surface layers (around the photospheres) at small radii and high luminosities. We find that the local spectrum transitions directly from a modified blackbody to a saturated Compton scattering spectrum as we increase the effective temperature and orbital frequency while decreasing midplane surface density. Next, we construct annuli models based on the parameters of a L/L{sub Edd} = 0.8 disk orbiting a 6.62 solar mass black hole using two modified dissipation profiles that explicitly put more dissipation per unit mass near the disk surface. The new dissipation profiles are qualitatively similar to the one found by Hirose et al., but produce strong near power-law spectral tails. Our models also include physically motivated magnetic acceleration support based once again on scaling the Hirose et al. results. We present three full-disk spectra, each based on one of the dissipation prescriptions. Our most aggressive dissipation profile results in a disk spectrum that is in approximate quantitative agreement with certain observations of the steep power-law spectral states from some black hole X-ray binaries.

Tao, Ted [Department of Physics, St. Mary's College of Maryland, St. Mary's City, MD 20686 (United States); Blaes, Omer [Department of Physics, University of California, Santa Barbara, CA 93106 (United States)

2013-06-10T23:59:59.000Z

337

Ejection of Supernova-Enriched Gas From Dwarf Disk Galaxies  

E-Print Network (OSTI)

We examine the efficiency with which supernova-enriched gas may be ejected from dwarf disk galaxies, using a methodology previously employed to study the self-enrichment efficiency of dwarf spheroidal systems. Unlike previous studies that focused on highly concentrated starbursts, in the current work we consider discrete supernova events spread throughout various fractions of the disk. We model disk systems having gas masses of 10^8 and 10^9 solar masses with supernova rates of 30, 300, and 3000 per Myr. The supernova events are confined to the midplane of the disk, but distributed over radii of 0, 30, and 80% of the disk radius, consistent with expectations for Type II supernovae. In agreement with earlier studies, we find that the enriched material from supernovae is largely lost when the supernovae are concentrated near the nucleus, as expected for a starburst event. In contrast, however, we find the loss of enriched material to be much less efficient when the supernovae occur over even a relatively small fraction of the disk. The difference is due to the ability of the system to relax following supernova events that occur over more extended regions. Larger physical separations also reduce the likelihood of supernovae going off within low-density "chimneys" swept out by previous supernovae. We also find that, for the most distributed systems, significant metal loss is more likely to be accompanied by significant mass loss. A comparison with theoretical predications indicates that, when undergoing self-regulated star formation, galaxies in the mass range considered shall efficiently retain the products of Type II supernovae.

P. Chris Fragile; Stephen D. Murray; Douglas N. C. Lin

2004-08-24T23:59:59.000Z

338

Modelling the formation and evolution of disk galaxies  

E-Print Network (OSTI)

Inspired by recent work on feedback in disk galaxies (Efstathiou 2000, Silk 2003) and on the angular momentum distribution in simulated gas halos (Sharma and Steinmetz 2005), a fully dynamic model of disk galaxy formation and evolution has been developed. This is used to demonstrate how observed galactic systems could have formed from halos similar to those found in simulations and applies physically motivated models of star formation and feedback to explore whether the true nature of these processes would be manifest from local and cosmological observables. This is made possible by computational integration with the galaxy formation model developed originally by the group at Durham University (Cole et al. 2000).

M. J. Stringer; A. J. Benson

2007-12-05T23:59:59.000Z

339

The Evolution of Dusty Debris Disks around Solar Type Stars  

Science Journals Connector (OSTI)

We used chromospheric activity to determine the ages of 2820 field stars. We searched these stars for excess emission at 22 ?m with the Wide-Field Infrared Survey Explorer. Such excess emission is indicative of a dusty debris disk around a star. We investigated how disk incidence trends with various stellar parameters, and how these parameters evolve with time. We found 22 ?m excesses around 98 stars (a detection rate of 3.5%). Of these 98 excess sources, 74 are presented here for the first time. We also measured the abundance of lithium in eight dusty stars in order to test our stellar age estimates.

Laura Vican; Adam Schneider

2014-01-01T23:59:59.000Z

340

Chemistry and line emission of outer protoplanetary disks  

E-Print Network (OSTI)

The structure and chemistry of protoplanetary disks depends strongly on the nature of the central star around which it has formed. The dust temperature is mainly set by the stellar luminosity, while the chemistry of the upper disk layers depends on the amount of intercepted UV and X-ray flux. We will study the differences in chemistry, thermal sturcture and line emission around Herbig Ae/Be, T Tauri stars and low mass M dwarfs. Predictions will be made for future observations with SOFIA and Herschel.

Inga Kamp; Cornelis P. Dullemond; Michiel Hogerheijde; Jesus Emilio Enriquez

2005-09-21T23:59:59.000Z

Note: This page contains sample records for the topic "brakes front disk" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


341

INJECTION OF SUPERNOVA DUST IN NEARBY PROTOPLANETARY DISKS  

SciTech Connect

The early solar system contained a number of short-lived radionuclides (SLRs) such as {sup 26}Al with half-lives <15 Myr. The one-time presence of {sup 60}Fe strongly suggests that the source of these radionuclides was a nearby supernova. In this paper, we investigate the 'aerogel' model, which hypothesizes that the solar system's SLRs were injected directly into the solar system's protoplanetary disk from a supernova within the same star-forming region. Previous work has shown that disks generally survive the impact of supernova ejecta, but also that little gaseous ejecta can be injected into the disk. The aerogel model hypothesizes that radionuclides in the ejecta condensed into micron-sized dust grains that were injected directly into the solar nebula disk. Here, we discuss the density structure of supernova ejecta and the observational support for dust condensation in the ejecta. We argue that supernova ejecta are clumpy and describe a model to quantify this clumpiness. We also argue that infrared observations may be underestimating the fraction of material that condenses into dust. Building on calculations of how supernova ejecta interact with protoplanetary disks, we calculate the efficiency with which dust grains in the ejecta are injected into a disk. We find that about 70% of material in grains roughly 0.4 {mu}m in diameter can be injected into disks. If ejecta are clumpy, the solar nebula was struck by a clump with higher-than-average {sup 26}Al and {sup 60}Fe, and these elements condensed efficiently into large grains, then the abundances of SLRs in the early solar system can be explained, even if the disk lies 2 pc from the supernova explosion. The probability that all these factors are met is low, perhaps {approx}10{sup -3}-10{sup -2}, and receiving as much {sup 26}Al and {sup 60}Fe as the solar system did may be a rare event. Still, the aerogel model remains a viable explanation for the origins of the radionuclides in the early solar system, and may be the most plausible one.

Ouellette, N. [Department of Physics, Arizona State University, P.O. Box 871504, Tempe, AZ 85287-1504 (United States); Desch, S. J.; Hester, J. J. [School of Earth and Space Exploration, Arizona State University, P.O. Box 871404, Tempe, AZ 85287-1404 (United States)

2010-03-10T23:59:59.000Z

342

Investigation of bit patterned media, thermal flying height control sliders and heat assisted magnetic recording in hard disk drives  

E-Print Network (OSTI)

experienced by sliders flying over disk coated with Z-the concept of one flying head per disk surface [22]. Theseslider when flying over textured magnetic disk media, in

Zheng, Hao

2011-01-01T23:59:59.000Z

343

Investigation of the effect of shock, vibration, surface texture and surface pattern on the dynamics of the head disk interface  

E-Print Network (OSTI)

Figure 7.8: Flying height as a function of disk speed forFigure 7.9: Flying height as a function of disk radius fortextured Flying Head Slider Bearings in Magnetic Hard Disk

Murthy, Aravind N.

2007-01-01T23:59:59.000Z

344

The missing cavities in the SEEDS polarized scattered light images of transitional protoplanetary disks: a generic disk model  

E-Print Network (OSTI)

Transitional circumstellar disks around young stellar objects have a distinctive infrared deficit around 10 microns in their Spectral Energy Distributions (SED), recently measured by the Spitzer Infrared Spectrograph (IRS), suggesting dust depletion in the inner regions. These disks have been confirmed to have giant central cavities by imaging of the submillimeter (sub-mm) continuum emission using the Submillimeter Array (SMA). However, the polarized near-infrared scattered light images for most objects in a systematic IRS/SMA cross sample, obtained by HiCIAO on the Subaru telescope, show no evidence for the cavity, in clear contrast with SMA and Spitzer observations. Radiative transfer modeling indicates that many of these scattered light images are consistent with a smooth spatial distribution for micron-sized grains, with little discontinuity in the surface density of the micron-sized grains at the cavity edge. Here we present a generic disk model that can simultaneously account for the general features in...

Dong, R; Zhu, Z; Hartmann, L; Whitney, B; Brandt, T; Muto, T; Hashimoto, J; Grady, C; Follette, K; Kuzuhara, M; Tanii, R; Itoh, Y; Thalmann, C; Wisniewski, J; Mayama, S; Janson, M; Abe, L; Brandner, W; Carson, J; Egner, S; Feldt, M; Goto, M; Guyon, O; Hayano, Y; Hayashi, M; Hayashi, S; Henning, T; Hodapp, K W; Honda, M; Inutsuka, S; Ishii, M; Iye, M; Kandori, R; Knapp, G R; Kudo, T; Kusakabe, N; Matsuo, T; McElwain, M W; Miyama, S; Morino, J -I; Moro-Martin, A; Nishimura, T; Pyo, T -S; Suto, H; Suzuki, R; Takami, M; Takato, N; Terada, H; Tomono, D; Turner, E L; Watanabe, M; Yamada, T; Takami, H; Usuda, T; Tamura, M

2012-01-01T23:59:59.000Z

345

SiGe receiver front ends and flip-chip integrated wideband antennas for millimeter-wave passive imaging  

E-Print Network (OSTI)

SiGe wideband 77-GHz and 94-GHz front end receivers with integrated antennas for passive imaging have been designed and characterized. These front end systems exhibit wideband performance with the highest gain and lowest ...

Powell, Johnna, 1980-

2009-01-01T23:59:59.000Z

346

Development of plastic front side panels for green cars  

Science Journals Connector (OSTI)

Lightweight design with thermoplastics is a robust approach in order to reduce the CO2 emission and fuel consumption. This paper reviews the role of plastics in the green concept of automobile and develops the design process for replacing steel front side panels, so called steel car fender, with plastic ones. Conceptual design, material selection, and design strategy in terms of strength, moldability, and assembility were proposed. Injection molding optimization was carried out in order to ensure the quality of the plastic fender under a certain manufacturing conditions such as the applied molding machine and auxiliary equipment. Prototype manufacturing was also implemented to verify the manufacturability and the feasibility of the development process of a plastic car fender. The weight of the plastic car fender is 1.15kg, reducing 41% compared to the steel fender. Although the production cost of the plastic fender is just slightly cheaper than that of steel one due to the high cost of the special plastic, the benefits such as lightweight, recyclability, manufacturability and design flexibility are the potential and practical application of the thermoplastic to the green automotive industry for making exterior parts.

H.S. Park; X.P. Dang; A. Roderburg; B. Nau

2013-01-01T23:59:59.000Z

347

Front-end electronics and trigger systems - status and challenges  

SciTech Connect

The past quarter century has brought about a revolution in front-end electronics for large-scale detector systems. Custom integrated circuits specifically tailored to the requirements of large detector systems have provided unprecedented performance and enabled systems that once were deemed impossible. The evolution of integrated circuit readouts in strip detectors is summarized, the present status described, and challenges posed by the sLHC and ILC are discussed. Performance requirements increase, but key considerations remain as in the past: power dissipation, material, and services. Smaller CMOS feature sizes will not provide the required electronic noise at lower power, but will improve digital power efficiency. Significant improvements appear to be practical in more efficient power distribution. Enhanced digital electronics have provided powerful trigger processors that greatly improve the trigger efficiency. In data readout systems they also improve data throughput, while reducing power requirements. Concurrently with new developments in high energy physics, detector systems for cosmology and astrophysics have made great strides. As an example, a large-scale readout for superconducting bolometer arrays is described.

Spieler, Helmuth G; Spieler, Helmuth G

2007-08-21T23:59:59.000Z

348

Inhibition of slug front corrosion in multiphase flow conditions  

SciTech Connect

Corrosion at the slug front at the bottom of a pipeline is identified as one of the worst cases of corrosion occurring in the pipeline which carries unprocessed multiphase production with a high level of CO{sub 2} gas. One objective of the study in recommending a subsea completion to shore was to determine if commercial corrosion inhibitors can control this type of corrosion using carbon steel pipeline. Thus, inhibitors which showed excellent performance in the lab using the Rotating Cylinder Electrode system (RCE) were further evaluated to confirm their performance in a flow loop simulating the test conditions predicted from the flow modeling for the proposed pipeline. The performance profile of two commercial inhibitors were determined in a 4 in. flow loop at 7O C, 100 psig CO{sub 2} partial pressure in corrosive brines with or without ethylene glycol and/or light hydrocarbon. Results showed that the carbon steel pipeline could be adequately protected at low temperature using a commercial corrosion inhibitor to meet the designed life of the pipeline. Ethylene glycol, which is used in the pipeline to prevent hydrate formation, reduces the corrosivity of the brine and gives no effect on inhibitor performance under the slug flow conditions. A good agreement in inhibitor performance was observed between the flow loop and the RCE testing. The uninhibited corrosion rate of the test brine in this study is in good agreement with the predicted value using deWaard and Williams correlation for CO{sub 2} corrosion.

Chen, H.J. [Chevron Petroleum Technology Co., La Habra, CA (United States); Jepson, W.P. [Ohio Univ., Athens, OH (United States)

1998-12-31T23:59:59.000Z

349

Characterization of the coherent noise, electromagnetic compatibility and electromagnetic interference of the ATLAS EM calorimeter Front End Board  

E-Print Network (OSTI)

Characterization of the coherent noise, electromagnetic compatibility and electromagnetic interference of the ATLAS EM calorimeter Front End Board

Chase, B E; Lanni, F; Makowiecki, D S; Radeka, V; Rescia, S; Takai, H; Bn, J; Parsons, J; Sippach, W

1999-01-01T23:59:59.000Z

350

A Novel Approximation Algorithm for Minimum Geometric Disk Cover Problem with Hexagon Tessellation  

Science Journals Connector (OSTI)

Given a set P ofn...points in the Euclidean plane, the minimum geometric disk cover (MGDC) problem is to identify a minimally sized set of congruent disks with prescribed radiusr that cover all the points in P. I...

Chi-Yu Chang; Chi-Chang Chen; Cheng-Chun Liu

2013-01-01T23:59:59.000Z

351

Room temperature and cryogenic Yb:YAG thin disk laser : single crystal and ceramic.  

E-Print Network (OSTI)

??The focus of this dissertation is to design, optimize and build an efficient high power multi kilowatt thin-disk laser system. We improve the thin-disk beam (more)

Vretenar, Natasa

2012-01-01T23:59:59.000Z

352

The flying height analysis of patterned sliders in magnetic hard disk drives  

Science Journals Connector (OSTI)

The ultra-low spacing of patterned sliders flying above a rotating disk with smooth surface in a hard disk drive is analyzed for high areal density ... slider are solved numerically to obtain the steady flying at...

W.-L. Li; S.-C. Lee; C.-W. Chen; F.-R. Tsai; M.-D. Chen

2005-01-01T23:59:59.000Z

353

Contact and temperature rise of thermal flying height control sliders in hard disk drives  

Science Journals Connector (OSTI)

Contact and interfacial temperature rise upon slider-disk contact in hard disk drives is investigated using thermal flying height control (TFC) sliders. To achieve ... increasing bias. The temperature rise during...

Liane Matthes; Uwe Boettcher; Bernhard Knigge

2012-09-01T23:59:59.000Z

354

Experimental study of sliderdisk interaction process with thermal-flying-height controlled slider  

Science Journals Connector (OSTI)

Thermal flying height (TFC) controlled slider has been introduced in hard disk drive recently. Flying height at the read/write elements of ... protrusion. Interactions between the TFC slider and disk can be very ...

Yansheng Ma; Bo Liu

2011-06-01T23:59:59.000Z

355

Dynamics of air bearing sliders flying on partially planarized bit patterned media in hard disk drives  

Science Journals Connector (OSTI)

Bit patterned media (BPM) recording is one of the promising techniques for future disk drives in order to increase the areal...2.... However, the BPM can change the topography of the disk surface and thus have an...

Liping Li; David B. Bogy

2011-06-01T23:59:59.000Z

356

E-Print Network 3.0 - accretion disk candidates Sample Search...  

NLE Websites -- All DOE Office Websites (Extended Search)

beamed bright spot on the accretion disk around the compact star. The long... the orbital inclination because the contribution of theM . accretion disk to the observed ux is...

357

E-Print Network 3.0 - accretion disk revealed Sample Search Results  

NLE Websites -- All DOE Office Websites (Extended Search)

beamed bright spot on the accretion disk around the compact star. The long... the orbital inclination because the contribution of theM . accretion disk to the observed ux is...

358

Light-Front Holography, AdS/QCD, and Hadronic Phenomena  

SciTech Connect

AdS/QCD, the correspondence between theories in a modified five-dimensional anti-de Sitter space and confining field theories in physical space-time, provides a remarkable semiclassical model for hadron physics. Light-front holography allows hadronic amplitudes in the AdS fifth dimension to be mapped to frame-independent light-front wavefunctions of hadrons in physical space-time, thus providing a relativistic description of hadrons at the amplitude level. We identify the AdS coordinate z with an invariant light-front coordinate {zeta} which separates the dynamics of quark and gluon binding from the kinematics of constituent spin and internal orbital angular momentum. The result is a single-variable light-front Schroedinger equation with a confining potential which determines the eigenspectrum and the light-front wavefunctions of hadrons for general spin and orbital angular momentum. The mapping of electromagnetic and gravitational form factors in AdS space to their corresponding expressions in light-front theory confirms this correspondence. Some novel features of QCD are discussed, including the consequences of confinement for quark and gluon condensates. The distinction between static structure functions, such as the probability distributions computed from the square of the light-front wavefunctions, versus dynamical structure functions which include the effects of rescattering, is emphasized. A new method for computing the hadronization of quark and gluon jets at the amplitude level, an event amplitude generator, is outlined.

Brodsky, Stanley J.; /SLAC; de Teramond, Guy F.; /Costa Rica U.

2009-12-09T23:59:59.000Z

359

Dynamic Transition in the Structure of an Energetic Crystal during Chemical Reactions at Shock Front Prior to Detonation  

E-Print Network (OSTI)

Front Prior to Detonation Ken-ichi Nomura, Rajiv K. Kalia, Aiichiro Nakano, and Priya Vashishta at shock fronts prior to detonation. Shock sensitivity measurements provide widely varying results that detonation is preceded by a transition from a diffuse shock front with well-ordered molecular dipoles behind

Southern California, University of

360

Fisher waves and front roughening in a two-species invasion model with preemptive competition L. O'Malley,1,  

E-Print Network (OSTI)

Fisher waves and front roughening in a two-species invasion model with preemptive competition L. O. We also study roughening of the front, using the framework of nonequilibrium interface growth. Our analysis indicates that initially flat, linear invad- ing fronts exhibit Kardar-Parisi-Zhang KPZ roughening

Rácz, Zoltán

Note: This page contains sample records for the topic "brakes front disk" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


361

Thermoplastic strengthening of a gas-turbine engine disk lock joint. Determination of the residual stresses  

Science Journals Connector (OSTI)

1. A unit has been created for investigating thermoplastic strengthening of turbine disk lock grooves on special...

B. A. Kravchenko; G. N. Gutman; L. E. Batrin; V. G. Fokin

1980-09-01T23:59:59.000Z

362

Modeling Hard-Disk Power Consumption John Zedlewski  

E-Print Network (OSTI)

, exhibit an almost insatiable demand for storage capacity. These devices have traditionally relied-limited. Recent advances in magnetic disk technology have made possible the development of high capacity, small of a note- book computer with a powerful lithium-ion battery, these levels of energy consumption are quite

Krishnamurthy, Arvind

363

General Relativistic Flux Modulations from Disk Instabilities in Sagittarius A*  

E-Print Network (OSTI)

Near-IR and X-ray flares have been detected from the supermassive black hole Sgr A* at the center of our Galaxy with a (quasi)-period of ~17-20 minutes, suggesting an emission region only a few Schwarzschild radii above the event horizon. The latest X-ray flare, detected with XMM-Newton, is notable for its detailed lightcurve, yielding not only the highest quality period thus far, but also important structure reflecting the geometry of the emitting region. Recent MHD simulations of Sgr A*'s disk have demonstrated the growth of a Rossby wave instability, that enhances the accretion rate for several hours, possibly accounting for the observed flares. In this Letter, we carry out ray-tracing calculations in a Schwarzschild metric to determine as accurately as possible the lightcurve produced by general relativistic effects during such a disruption. We find that the Rossby wave induced spiral pattern in the disk is an excellent fit to the data, implying a disk inclination angle of ~77 deg. Note, however, that if this association is correct, the observed period is not due to the underlying Keplerian motion but, rather, to the pattern speed. The favorable comparison between the observed and simulated lightcurves provides important additional evidence that the flares are produced in Sgr A*'s inner disk.

Maurizio Falanga; Fulvio Melia; Michel Tagger; Andrea Goldwurm; Guillaume Belanger

2007-05-02T23:59:59.000Z

364

A probable giant planet imaged in the Beta Pictoris disk  

E-Print Network (OSTI)

Since the discovery of its dusty disk in 1984, Beta Pictoris has become the prototype of young early-type planetary systems, and there are now various indications that a massive Jovian planet is orbiting the star at ~ 10 AU. However, no planets have been detected around this star so far. Our goal was to investigate the close environment of Beta Pic, searching for planetary companion(s). Deep adaptive-optics L'-band images of Beta Pic were recorded using the NaCo instrument at the Very Large Telescope. A faint point-like signal is detected at a projected distance of ~ 8 AU from the star, within the North-East side of the dust disk. Various tests were made to rule out with a good confidence level possible instrumental or atmospheric artifacts. The probability of a foreground or background contaminant is extremely low, based in addition on the analysis of previous deep Hubble Space Telescope images. The object L'=11.2 apparent magnitude would indicate a typical temperature of ~1500 K and a mass of ~ 8 Jovian masses. If confirmed, it could explain the main morphological and dynamical peculiarities of the Beta Pic system. The present detection is unique among A-stars by the proximity of the resolved planet to its parent star. Its closeness and location inside the Beta Pic disk suggest a formation process by core accretion or disk instabilities rather than a binary-like formation process.

A. -M. Lagrange; D. Gratadour; G. Chauvin; T. Fusco; D. Ehrenreich; D. Mouillet; G. Rousset; D. Rouan; F. Allard; E. Gendron; J. Charton; L. Mugnier; P. Rabou; J. Montri; F. Lacombe

2008-11-21T23:59:59.000Z

365

Characterization of Thermal Response Induced by Head/Disk Interaction in Current TGMR Head  

E-Print Network (OSTI)

, resulting in variations in head flying characteristics. Therefore, head- disk interaction in real disk driveCharacterization of Thermal Response Induced by Head/Disk Interaction in Current TGMR Head Suwatana with a lower areal resistance (RA) value. However, as the areal density increases, the actual flying clearance

Kovintavewat, Piya

366

STRAIN SENSING WITH PIEZOELECTRIC ZINC OXIDE THIN FILMS FOR VIBRATION SUPPRESSION IN HARD DISK DRIVES  

E-Print Network (OSTI)

was successfully obtained while the suspension was flying on a disk as in normal drive operation. PreliminarySTRAIN SENSING WITH PIEZOELECTRIC ZINC OXIDE THIN FILMS FOR VIBRATION SUPPRESSION IN HARD DISK This paper describes the integration of thin film ZnO strain sensors onto hard disk drive suspensions

Horowitz, Roberto

367

Formation of Sets and Subsets of Informative Features of Information Carriers with Magnetic Hard Disks*  

E-Print Network (OSTI)

to the substrate. The Protective Layer (PL) improves the flying of the magnetic heads above the magnetic disks Hard Disks* Ognjan Tzarnoretchki, Daniela Borissova Institute of Information Technologies, 1113 Sofia magnetic disk, new informative features are presented, which form a substantial subset of the informative

Borissova, Daniela

368

Microsoft Word - solcar95.html  

NLE Websites -- All DOE Office Websites (Extended Search)

FORCE FORCE VEHICLE SPECIFICATIONS CONVERTED VEHICLE Base Vehicle: 1995 Geo Metro VIN:2C1MR529XS6783464 Seatbelt Positions: Three Standard Features: Power Brakes Front Disk Brakes Front Wheel Drive Dual Air Bags AM/FM Stereo Radio w/Cassette Electric Heater Options as Tested: None BATTERY Manufacturer: GM Ovonic Type: 13.2EV85 Nickel Metal Hydride Number of Modules: 14 Weight of Module: 18 kg Weight of Pack(s): 254 kg Pack Locations: Undertrunk/Underhood Nominal Module Voltage: 13.2 V Nominal System Voltage: 185 V Nominal Capacity (1C): 85 Ah WEIGHTS Design Curb Weight: 2246 lbs Delivered Curb Weight: 2304 lbs Distribution F/R: 50/50 % GVWR: 2755 lbs GAWR F/R: 1432/1366 lbs Payload: 451 lbs Performance Goal: 664 lbs DIMENSIONS Wheelbase: 93.5 inches

369

Microscopic Examination of a Corrosion Front in Spent Nuclear Fuel  

SciTech Connect

Spent uranium oxide nuclear fuel hosts a variety of trace chemical constituents, many of which must be sequestered from the biosphere during fuel storage and disposal. In this paper we present synchrotron x-ray absorption spectroscopy and microscopy findings that illuminate the resultant local chemistry of neptunium and plutonium within spent uranium oxide nuclear fuel before and after corrosive alteration in an air-saturated aqueous environment. We find the plutonium and neptunium in unaltered spent fuel to have a +4 oxidation state and an environment consistent with solid-solution in the UO{sub 2} matrix. During corrosion in an air-saturated aqueous environment, the uranium matrix is converted to uranyl U(VI)O{sub 2}{sup 2+} mineral assemblage that is depleted in plutonium and neptunium relative to the parent fuel. At the corrosion front interface between intact fuel and the uranyl-mineral corrosion layer, we find evidence of a thin ({approx}20 micrometer) layer that is enriched in plutonium and neptunium within a predominantly U{sup 4+} environment. Available data for the standard reduction potentials for NpO{sup 2+}/Np{sup 4+} and UO{sub 2}{sup 2+}/U{sup 4+} couples indicate that Np(IV) may not be effectively oxidized to Np(V) at the corrosion potentials of uranium dioxide spent nuclear fuel in air-saturated aqueous solutions. Neptunium is an important radionuclide in dose contribution according to performance assessment models of the proposed U. S. repository at Yucca Mountain, Nevada. A scientific understanding of how the UO{sub 2} matrix of spent nuclear fuel impacts the oxidative dissolution and reductive precipitation of neptunium is needed to predict its behavior at the fuel surface during aqueous corrosion. Neptunium would most likely be transported as aqueous Np(V) species, but for this to occur it must first be oxidized from the Np(IV) state found within the parent spent nuclear fuel [1]. In the immediate vicinity of the spent fuel's surface the redox and nucleation behavior is likely to promote/enhance nucleation of NpO{sub 2} and Np{sub 2}O{sub 5}. Alternatively, Np may be incorporated into uranyl (UO{sub 2}{sup 2+}) alteration phases [2]. In some cases, less-soluble elements such as plutonium will be enriched near the surface of the corroding fuel [3]. We have used focused synchrotron x-rays from the MRCAT beam line at the Advanced Photon Source (APS) at Argonne National Lab to examine a specimen of spent nuclear fuel that had been subject to 10 years of corrosion testing in an environment of humid air and dripping groundwater at 90 C [4]. We find evidence of a region, approximately 20 microns in thickness, enriched in plutonium and neptunium at the corrosion front that exists between the uranyl silicate alteration mineral rind and the unaltered uranium oxide fuel (Figures 1 and 2). The uranyl silicate is itself found to be depleted in these transuranic elements relative to their abundance relative to uranium in the parent fuel. This suggests a low mobility of these components owing to a resistance to oxidize further in the presence of a UO{sub 2}{sup 2+}/U{sup 4+} couple [5].

J.A> Fortner; A.J. Kropf; R.J. Finch; J.C. Cunnane

2006-06-20T23:59:59.000Z

370

Front Vehicle Setup Information Downloadable Dynamometer Database (D  

NLE Websites -- All DOE Office Websites (Extended Search)

Chevrolet Volt- 20F Chevrolet Volt- 20F Test cell location Front Vehicle Setup Information Downloadable Dynamometer Database (D 3 )- Test Summary Sheet Vehicle architecture EREV Vehicle dynamometer Input Document date 8/7/2013 Advanced Powertrain Research Facility Test weight [lb] Target A [lb] 4000 28.66 Target B [lb/mph] Target C [lb/mph^2] -0.0132 0.0202 Revision Number 3 Notes: Test Fuel Information Fuel type EPA Tier II EEE Fuel density [g/ml] Fuel Net HV [BTU/lbm] 0.743 18490 T e s t I D [ # ] C y c l e C o l d s t a r t ( C S t ) H o t s t a r t [ H S t ] D a t e T e s t C e l l T e m p [ C ] T e s t C e l l R H [ % ] T e s t C e l l B a r o [ i n / H g ] V e h i c l e c o o l i n g f a n s p e e d : S p e e d M a t c h [ S M ] o r c o n s t a n t s p e e d [ C S ] S o l a r L a m p s [ W / m 2 ] V e i c l e C l i m a t e C o n t r o l s e t t i n g s H o o d P o s i t i o n [ U p ] o r [ C l o s e d ] W i n d o w P o s i t i o n [ C l o s e d ] o r [ D o w n ] C y c l e D i s t a n c e [ m i ] C y c l e F u

371

SHOCKS AND THERMAL CONDUCTION FRONTS IN RETRACTING RECONNECTED FLUX TUBES  

SciTech Connect

We present a model for plasma heating produced by time-dependent, spatially localized reconnection within a flare current sheet separating skewed magnetic fields. The reconnection creates flux tubes of new connectivity which subsequently retract at Alfvenic speeds from the reconnection site. Heating occurs in gas-dynamic shocks (GDSs) which develop inside these tubes. Here we present generalized thin flux tube equations for the dynamics of reconnected flux tubes, including pressure-driven parallel dynamics as well as temperature-dependent, anisotropic viscosity and thermal conductivity. The evolution of tubes embedded in a uniform, skewed magnetic field, following reconnection in a patch, is studied through numerical solutions of these equations, for solar coronal conditions. Even though viscosity and thermal conductivity are negligible in the quiet solar corona, the strong GDSs generated by compressing plasma inside reconnected flux tubes generate large velocity and temperature gradients along the tube, rendering the diffusive processes dominant. They determine the thickness of the shock that evolves up to a steady state value, although this condition may not be reached in the short times involved in a flare. For realistic solar coronal parameters, this steady state shock thickness might be as long as the entire flux tube. For strong shocks at low Prandtl numbers, typical of the solar corona, the GDS consists of an isothermal sub-shock where all the compression and cooling occur, preceded by a thermal front where the temperature increases and most of the heating occurs. We estimate the length of each of these sub-regions and the speed of their propagation.

Guidoni, S. E.; Longcope, D. W., E-mail: guidoni@physics.montana.ed [Department of Physics, Montana State University, Bozeman, MT 59717-3840 (United States)

2010-08-01T23:59:59.000Z

372

DOE Offers Conditional Loan Guarantee for Front End Nuclear Facility in  

Energy.gov (U.S. Department of Energy (DOE)) Indexed Site

DOE Offers Conditional Loan Guarantee for Front End Nuclear DOE Offers Conditional Loan Guarantee for Front End Nuclear Facility in Idaho DOE Offers Conditional Loan Guarantee for Front End Nuclear Facility in Idaho May 20, 2010 - 12:00am Addthis Washington, DC - As part of a broad effort to expand the use of nuclear power in the United States and reduce carbon pollution, U.S. Secretary of Energy Steven Chu announced today the Department's first conditional commitment for a front-end nuclear facility. The $2 billion loan guarantee will support AREVA's Eagle Rock Enrichment Facility near Idaho Falls, Idaho, which will supply uranium enrichment services for the U.S. nuclear power industry. "Increasing uranium enrichment in the United States is critical to the nation's energy and national security," said Secretary Chu. "Existing

373

On the Variability of Antarctic Circumpolar Current Fronts Inferred from 19922011 Altimetry  

Science Journals Connector (OSTI)

Antarctic Circumpolar Current (ACC) fronts, defined as water mass boundaries, have been known to respond to large-scale atmospheric variabilities, especially the Southern Hemisphere annular mode (SAM) and El NioSouthern Oscillation (ENSO). ...

Yong Sun Kim; Alejandro H. Orsi

2014-12-01T23:59:59.000Z

374

26-percent efficient point-junction concentrator solar cells with a front metal grid  

SciTech Connect

This paper reports on silicon concentrator cells with point diffusions and metal contacts on both the front and back sides. The design minimizes reflection losses by forming an inverted pyramid topography on the front surface and by shaping the metal grid lines in the form of a triangular ridge. A short-circuit current density of 39.6 mA/cm{sup 2} has been achieved even though the front grid covers 16 percent of the cell's active area of 1.56 cm{sup 2}. This, together with an open-circuit voltage of 700 mV, has led to an efficiency of 22 percent at one sun, AM1.5 global spectrum. Under direct-spectrum, 8.8-W/cm{sup 2}, concentrated light, the efficiency is 26 percent. This is the highest ever reported for a silicon cell having a front metal grid.

Cuevas, A.; Sinton, R.A.; Midkiff, N.E.; Swanson, R.M. (Stanford Univ., CA (USA). Dept. of Electrical Engineering)

1990-01-01T23:59:59.000Z

375

Dynamics of Curved Detonation Front and Critical Conditions for Detonation Initiations  

Science Journals Connector (OSTI)

The curved detonation front appears in a number of unsteady phenomena such as the diffraction of detonations, the initiation of detonation by a point energy source, by a ... propagating velocity D and the curvatu...

L. He

1997-01-01T23:59:59.000Z

376

Mechanisms of accelerated degradation in the front cells of PEMFC stacks and some mitigation strategies  

Science Journals Connector (OSTI)

The accelerated degradation in the front cells of a polymer electrolyte membrane fuel cell(PEMFC) stack seriously reduces the reliability and ... to find out the mechanisms of the accelerated degradation in the f...

Pengcheng Li; Pucheng Pei; Yongling He

2013-11-01T23:59:59.000Z

377

E-Print Network 3.0 - aps beamline front Sample Search Results  

NLE Websites -- All DOE Office Websites (Extended Search)

Page 1 of 11 Policy& Procedure : 3.1.37 Summary: The beamline front end provides the UHV transition from the APS storage ring through the ratchet wall... to the portions of the...

378

E-Print Network 3.0 - alice tpc front Sample Search Results  

NLE Websites -- All DOE Office Websites (Extended Search)

(ALICE) A.V.Khanzadeev, V.N.Nikulin, V.V.Poliakov, V.M.Samsonov Summary: in the Forward Muon Spectrometer. As mentioned above, the ALICE muon spectrometer consists of the front......

379

Autonomous detection and anticipation of jam fronts from messages propagated by inter-vehicle communication  

E-Print Network (OSTI)

In this paper, a minimalist, completely distributed freeway traffic information system is introduced. It involves an autonomous, vehicle-based jam front detection, the information transmission via inter-vehicle communication, and the forecast of the spatial position of jam fronts by reconstructing the spatiotemporal traffic situation based on the transmitted information. The whole system is simulated with an integrated traffic simulator, that is based on a realistic microscopic traffic model for longitudinal movements and lane changes. The function of its communication module has been explicitly validated by comparing the simulation results with analytical calculations. By means of simulations, we show that the algorithms for a congestion-front recognition, message transmission, and processing predict reliably the existence and position of jam fronts for vehicle equipment rates as low as 3%. A reliable mode of operation already for small market penetrations is crucial for the successful introduction of inter-...

Sch"onhof, M; Kesting, A; Helbing, D; Sch\\"onhof, Martin; Treiber, Martin; Kesting, Arne; Helbing, Dirk

2006-01-01T23:59:59.000Z

380

E-Print Network 3.0 - augmented hadronic light-front Sample Search...  

NLE Websites -- All DOE Office Websites (Extended Search)

Jagiellonski Collection: Physics 5 Vol. 32 (2001) ACTA PHYSICA POLONICA B No 12 QCD PHENOMENOLOGY AND LIGHT-FRONT Summary: of a hadrons in terms of a set of frame-independent...

Note: This page contains sample records for the topic "brakes front disk" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


381

DOE Offers Conditional Loan Guarantee for Front End Nuclear Facility in  

Energy.gov (U.S. Department of Energy (DOE)) Indexed Site

DOE Offers Conditional Loan Guarantee for Front End Nuclear DOE Offers Conditional Loan Guarantee for Front End Nuclear Facility in Idaho DOE Offers Conditional Loan Guarantee for Front End Nuclear Facility in Idaho May 20, 2010 - 12:00am Addthis Washington, DC - As part of a broad effort to expand the use of nuclear power in the United States and reduce carbon pollution, U.S. Secretary of Energy Steven Chu announced today the Department's first conditional commitment for a front-end nuclear facility. The $2 billion loan guarantee will support AREVA's Eagle Rock Enrichment Facility near Idaho Falls, Idaho, which will supply uranium enrichment services for the U.S. nuclear power industry. "Increasing uranium enrichment in the United States is critical to the nation's energy and national security," said Secretary Chu. "Existing

382

Limits on iron-dominated fallback disk in SN 1987A  

E-Print Network (OSTI)

The non-detection of a point source in SN1987A imposes an upper limit for the optical luminosity of L=2L_sun. This limits the size of a possible fallback disk around the stellar remnant. Assuming a steady-state thin disk with blackbody emission requires a disk smaller than 100,000 km if the accretion rate is at 30% of the Eddington rate (Graves et al. 2005). We have performed detailed non-LTE radiation transfer calculations to model the disk spectrum more realistically. It turns out that the observational limit on the disk extension becomes even tighter, namely 70,000 km.

K. Werner; T. Nagel; T. Rauch

2007-03-20T23:59:59.000Z

383

Non-Adiabatic Effects on Combustion Front Propagation in Porous Media: Multiplicity of Steady States  

SciTech Connect

The sustained propagation of combustion fronts in porous media is a necessary condition for the success of an in situ combustion project for oil recovery. Compared to other recovery methods, in situ combustion involves the added complexity of exothermic reactions and temperature-dependent chemical kinetics. In the presence of heat losses, the possibility of ignition and extinction (quenching) exists. In this report, we address the properties of combustion fronts propagating at a constant velocity in the presence of heat losses.

Akkutlu, I. Yucel; Yortsos, Yanis C.

2002-03-11T23:59:59.000Z

384

Self Energy Correction in Light Front QED And Coherent State Basis  

E-Print Network (OSTI)

We discuss the calculation of fermion self energy correction in Light Front QED using a coherent state basis. We show that if one uses coherent state basis instead of fock basis to calculate the transition matrix elements, the true infrared divergences in electron mass renormalization $\\delta m^2$ get canceled up to $O(e^4)$ in Light Front gauge. We have also verified this cancellation in Feynman gauge up to $O(e^2)$.

Jai D. More; Anuradha Misra

2013-09-10T23:59:59.000Z

385

THE 0.5-2.22 {mu}m SCATTERED LIGHT SPECTRUM OF THE DISK AROUND TW Hya: DETECTION OF A PARTIALLY FILLED DISK GAP AT 80 AU  

SciTech Connect

We present a 0.5-2.2 {mu}m scattered light spectrum of the circumstellar disk around TW Hya from a combination of spatially resolved Hubble Space Telescope STIS spectroscopy and NICMOS coronagraphic images of the disk. We investigate the morphology of the disk at distances >40 AU over this wide range of wavelengths, and identify the presence of a depression in surface brightness at {approx}80 AU that could be caused by a gap in the disk. Additionally, we quantify the surface brightness, azimuthal symmetry, and spectral character of the disk as a function of radius. Our analysis shows that the scattering efficiency of the dust is largely neutral to blue over the observed wavelengths. We model the disk as a steady {alpha}-disk with an ad hoc gap structure. The thermal properties of the disk are self-consistently calculated using a three-dimensional radiative transfer code that uses ray tracing to model the heating of the disk interior and scattered light images. We find a good fit to the data over a wide range of distances from the star if we use a model disk with a partially filled gap of 30% depth at 80 AU and with a self-similar truncation knee at 100 AU. The origin of the gap is unclear, but it could arise from a transition in the nature of the disk's dust composition or the presence of a planetary companion. Based on scalings to previous hydrodynamic simulations of gap-opening criteria for embedded proto-planets, we estimate that a planetary companion forming the gap could have a mass between 6 and 28 M{sub Circled-Plus }.

Debes, John H. [Space Telescope Science Institute, Baltimore, MD 21218 (United States); Jang-Condell, Hannah [University of Wyoming, Laramie, WY 82071 (United States); Weinberger, Alycia J. [Department of Terrestrial Magnetism, Carnegie Institution of Washington, Washington, DC 20015 (United States); Roberge, Aki [Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Schneider, Glenn [Steward Observatory, University of Arizona, Tuscon, AZ 85721 (United States)

2013-07-01T23:59:59.000Z

386

Galaxies that Shine: radiation-hydrodynamical simulations of disk galaxies  

E-Print Network (OSTI)

Radiation feedback is typically implemented using subgrid recipes in hydrodynamical simulations of galaxies. Very little work has so far been performed using radiation-hydrodynamics (RHD), and there is no consensus on the importance of radiation feedback in galaxy evolution. We present RHD simulations of isolated galaxy disks of different masses with a resolution of 18 pc. Besides accounting for supernova feedback, our simulations are the first galaxy-scale simulations to include RHD treatments of photo-ionisation heating and radiation pressure, from both direct optical/UV radiation and multi-scattered, re-processed infrared (IR) radiation. Photo-heating smooths and thickens the disks and suppresses star formation about as much as the inclusion of ("thermal dump") supernova feedback does. These effects decrease with galaxy mass and are mainly due to the prevention of the formation of dense clouds, as opposed to their destruction. Radiation pressure, whether from direct or IR radiation, has little effect, but ...

Rosdahl, Joakim; Teyssier, Romain; Agertz, Oscar

2015-01-01T23:59:59.000Z

387

Tribo-chemistry at the head/disk interface  

SciTech Connect

Tribo-chemical studies at the head/disk interface (HDI) were conducted on hydrogenated (CH{sub x}), nitrogenated (CN{sub x}), and cathodic-arc amorphous hard carbon disk samples coated with perfluoropolyether ZDOL and X1P/ZDOL lubricant. The studies involved drag tests with uncoated and carbon-coated Al{sub 2}O{sub 3}-TiC sliders and thermal desorption experiments in an ultra-high vacuum (UHV) tribochamber followed with a surface chemistry analysis by X-ray Photo Emission Electron Microscopy (X-PEEM) and Near Edge X-ray Absorption Fine Structure (NEXAFS) spectroscopy. The friction and catalytic decomposition mechanisms of ZDOL are described, as well as the tribo-chemical performance of cathodic-arc carbon overcoats coated with ZDOL, and data demonstrating the chemical alteration of the lubricant and carbon overcoat are also presented.

Bhatia, C.S. [SSD/IBM, San Jose, CA (United States)] [SSD/IBM, San Jose, CA (United States); Fong, W.; Chen, C.Y.; Wei, J.; Bogy, D.B. [Univ. of California, Berkeley, CA (United States). Computer Mechanics Lab.] [Univ. of California, Berkeley, CA (United States). Computer Mechanics Lab.; Anders, S.; Stammler, T. [Lawrence Berkeley National Lab., CA (United States)] [Lawrence Berkeley National Lab., CA (United States); Stoehr, J. [IBM Research Div., San Jose, CA (United States)] [IBM Research Div., San Jose, CA (United States)

1999-03-01T23:59:59.000Z

388

THE MASS DEPENDENCE BETWEEN PROTOPLANETARY DISKS AND THEIR STELLAR HOSTS  

SciTech Connect

We present a substantial extension of the millimeter (mm) wave continuum photometry catalog for circumstellar dust disks in the Taurus star-forming region, based on a new ''snapshot'' {lambda} = 1.3 mm survey with the Submillimeter Array. Combining these new data with measurements in the literature, we construct a mm-wave luminosity distribution, f(L{sub mm}), for Class II disks that is statistically complete for stellar hosts with spectral types earlier than M8.5 and has a 3{sigma} depth of roughly 3 mJy. The resulting census eliminates a longstanding selection bias against disks with late-type hosts, and thereby demonstrates that there is a strong correlation between L{sub mm} and the host spectral type. By translating the locations of individual stars in the Hertzsprung-Russell diagram into masses and ages, and adopting a simple conversion between L{sub mm} and the disk mass, M{sub d} , we confirm that this correlation corresponds to a statistically robust relationship between the masses of dust disks and the stars that host them. A Bayesian regression technique is used to characterize these relationships in the presence of measurement errors, data censoring, and significant intrinsic scatter: the best-fit results indicate a typical 1.3 mm flux density of {approx}25 mJy for 1 M{sub Sun} hosts and a power-law scaling L{sub mm}{proportional_to}M{sub *}{sup 1.5-2.0}. We suggest that a reasonable treatment of dust temperature in the conversion from L{sub mm} to M{sub d} favors an inherently linear M{sub d} {proportional_to}M{sub *} scaling, with a typical disk-to-star mass ratio of {approx}0.2%-0.6%. The measured rms dispersion around this regression curve is {+-}0.7 dex, suggesting that the combined effects of diverse evolutionary states, dust opacities, and temperatures in these disks imprint a full width at half-maximum range of a factor of {approx}40 on the inferred M{sub d} (or L{sub mm}) at any given host mass. We argue that this relationship between M{sub d} and M{sub *} likely represents the origin of the inferred correlation between giant planet frequency and host star mass in the exoplanet population, and provides some basic support for the core accretion model for planet formation. Moreover, we caution that the effects of incompleteness and selection bias must be considered in comparative studies of disk evolution, and illustrate that fact with statistical comparisons of f(L{sub mm}) between the Taurus catalog presented here and incomplete subsamples in the Ophiuchus, IC 348, and Upper Sco young clusters.

Andrews, Sean M.; Rosenfeld, Katherine A.; Kraus, Adam L.; Wilner, David J., E-mail: sandrews@cfa.harvard.edu [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States)

2013-07-10T23:59:59.000Z

389

Adaptor assembly for coupling turbine blades to rotor disks  

DOE Patents (OSTI)

An adaptor assembly for coupling a blade root of a turbine blade to a root slot of a rotor disk is described. The adaptor assembly includes a turbine blade having a blade root and an adaptor body having an adaptor root. The adaptor body defines a slot having an open end configured to receive the blade root of the turbine blade such that the adaptor root of the adaptor body and the blade root of the turbine blade are adjacent to one another when the blade root of the turbine blade is positioned within the slot. Both the adaptor root of the adaptor body and the blade root of the turbine blade are configured to be received within the root slot of the rotor disk.

Garcia-Crespo, Andres Jose; Delvaux, John McConnell

2014-09-23T23:59:59.000Z

390

Fracture toughness measurements with subsize disk compact specimens  

SciTech Connect

Special fixtures and test methods have been developed for testing small disk compact specimens (1.25 mm diam by 4.6 mm thick). Specimens of European type 316L austenitic stainless steel were irradiated to damage levels of about 3 dpa at nominal irradiation temperatures of either 90 or 250 C and tested over a temperature range from 20 to 250 C. Results show that irradiation to this dose level at these temperatures reduces the fracture toughness but the toughness remains quite high. The toughness decreases as the test temperature increases. Irradiation at 250 C is more damaging than at 90 C, causing larger decreases in the fracture toughness. The testing shows that it is possible to generate useful fracture toughness data with a small disk compact specimens.

Alexander, D.J.

1994-12-31T23:59:59.000Z

391

Kinematics of classical Cepheids in the Nuclear Stellar Disk  

E-Print Network (OSTI)

Classical Cepheids are useful tracers of the Galactic young stellar population because their distances and ages can be determined from their period-luminosity and period-age relations. In addition, the radial velocities and chemical abundance of the Cepheids can be derived from spectroscopic observations, providing further insights into the structure and evolution of the Galaxy. Here, we report the radial velocities of classical Cepheids near the Galactic Center, three of which were reported in 2011, the other reported for the first time. The velocities of these Cepheids suggest that the stars orbit within the Nuclear Stellar Disk, a group of stars and interstellar matter occupying a region of 200 pc around the Center, although the three-dimensional velocities cannot be determined until the proper motions are known. According to our simulation, these four Cepheids formed within the Nuclear Stellar Disk like younger stars and stellar clusters therein.

Matsunaga, N; Yamamoto, R; Kobayashi, N; Inno, L; Genovali, K; Bono, G; Baba, J; Fujii, M S; Kondo, S; Ikeda, Y; Hamano, S; Nishiyama, S; Nagata, T; Aoki, W; Tsujimoto, T

2014-01-01T23:59:59.000Z

392

Wet-steam erosion of steam turbine disks and shafts  

SciTech Connect

A study of wet-steam erosion of the disks and the rotor bosses or housings of turbines in thermal and nuclear power plants shows that the rate of wear does not depend on the diagrammed degree of moisture, but is determined by moisture condensing on the surfaces of the diaphragms and steam inlet components. Renovating the diaphragm seals as an assembly with condensate removal provides a manifold reduction in the erosion.

Averkina, N. V. [JSC 'NPO TsKTI' (Russian Federation); Zheleznyak, I. V. [Leningradskaya AES branch of JSC 'Kontsern Rosenergoatom' (Russian Federation); Kachuriner, Yu. Ya.; Nosovitskii, I. A.; Orlik, V. G., E-mail: orlikvg@mail.ru [JSC 'NPO TsKTI' (Russian Federation); Shishkin, V. I. [Leningradskaya AES branch of JSC 'Kontsern Rosenergoatom' (Russian Federation)

2011-01-15T23:59:59.000Z

393

Massive Pellet and Rupture Disk Testing for Disruption Mitigation Applications  

SciTech Connect

Injection of massive quantities of noble gases or D2 has proven to be effective at mitigating some of the deleterious effects of disruptions in tokamaks. Two alternative methods that might offer some advantages over the present technique for massive gas injection are shattering massive pellets and employing close-coupled rupture disks. Laboratory testing has been carried out to evaluate their feasibility. For the study of massive pellets, a pipe gun pellet injector cooled with a cryogenic refrigerator was fitted with a relatively large barrel (16.5 mm bore), and D2 and Ne pellets were made and were accelerated to speeds of ~600 and 300 m/s, respectively. Based on the successful proof-of-principle testing with the injector and a special double-impact target to shatter pellets, a similar system has been prepared and installed on DIII-D and should be ready for experiments later this year. To study the applicability of rupture disks for disruption mitigation, a simple test apparatus was assembled in the lab. Commercially available rupture disks of 1 in. nominal diameter were tested at conditions relevant for the application on tokamaks, including tests with Ar and He gases and rupture pressures of ~54 bar. Some technical and practical issues of implementing this technique on a tokamak are discussed.

Combs, Stephen Kirk [ORNL] [ORNL; Meitner, Steven J [ORNL] [ORNL; Baylor, Larry R [ORNL] [ORNL; Caughman, John B [ORNL] [ORNL; Commaux, Nicolas JC [ORNL] [ORNL; Fehling, Dan T [ORNL] [ORNL; Foust, Charles R [ORNL] [ORNL; Jernigan, Thomas C [ORNL] [ORNL; McGill, James M [ORNL] [ORNL; Parks, P. B. [General Atomics] [General Atomics; Rasmussen, David A [ORNL] [ORNL

2009-01-01T23:59:59.000Z

394

GALACTOSEISMOLOGY: DISCOVERY OF VERTICAL WAVES IN THE GALACTIC DISK  

SciTech Connect

We present evidence for a Galactic North-South asymmetry in the number density and bulk velocity of solar neighborhood stars. The number density profile, which is derived from main-sequence stars in the Sloan Digital Sky Survey, shows a (North-South)/(North+South) deficit at |z| {approx_equal} 400 pc and an excess at |z| {approx} 800 pc. The bulk velocity profile, which is derived from the Sloan Extension for Galactic Understanding and Exploration, shows a gradual trend across the Galactic midplane as well as smaller-scale features. We speculate that the North-South asymmetry, which has the appearance of a wavelike perturbation, is intrinsic to the disk. We explore the physics of this phenomenon through an analysis of the linearized Boltzmann and Poisson equations and through one-dimensional simulations. The perturbation may be excited by the passage of a satellite galaxy or dark matter subhalo through the Galactic disk, in which case we are witnessing a recent disk-heating event.

Widrow, Lawrence M. [Department of Physics, Engineering Physics, and Astronomy, Queen's University, Kingston, ON K7L 3N6 (Canada); Gardner, Susan [Department of Physics and Astronomy, University of Kentucky, Lexington, KY 40506-0055 (United States); Yanny, Brian; Dodelson, Scott [Fermi National Accelerator Laboratory, Batavia, IL 60510 (United States); Chen, Hsin-Yu [Department of Astronomy and Astrophysics, The University of Chicago, Chicago, IL 60637 (United States)

2012-05-10T23:59:59.000Z

395

The dynamical structure of HR 8799's inner debris disk  

E-Print Network (OSTI)

The HR 8799 system, with its four giant planets and two debris belts, has an architecture closely mirroring that of our Solar system where the inner, warm asteroid belt and outer, cool Edgeworth-Kuiper belt bracket the giant planets. As such, it is a valuable laboratory for examining exoplanetary dynamics and debris disk-exoplanet interactions. Whilst the outer debris belt of HR 8799 has been well resolved by previous observations, the spatial extent of the inner disk remains unknown. This leaves a significant question mark over both the location of the planetesimals responsible for producing the belt's visible dust and the physical properties of those grains. We have performed the most extensive simulations to date of the inner, unresolved debris belt around HR 8799, using UNSW Australia's Katana supercomputing facility to follow the dynamical evolution of a model inner disk comprising 300,298 particles for a period of 60 million years. These simulations have enabled the characterisation of the extent and st...

Contro, Bruna; Horner, Jonti; Marshall, Jonathan P

2015-01-01T23:59:59.000Z

396

Stationary Nonaxisymmetric Configurations of Magnetized Singular Isothermal Disks  

E-Print Network (OSTI)

Accepted.... Received...; in original form... We construct both aligned and unaligned (logarithmic spiral) stationary configurations of nonaxisymmetric magnetohydrodynamic (MHD) disks from either a full or a partial razor-thin power-law axisymmetric magnetized singular isothermal disk (MSID) that is embedded with a coplanar azimuthal magnetic field B? of a non-force-free radial scaling r?1/2 and that rotates differentially with a flat rotation curve of speed aD, where a is the isothermal sound speed and D is the dimensionless rotation parameter. Analytical solutions and stability criteria for determining D2 are derived. For aligned nonaxisymmetric MSIDs, eccentric m = 1 displacements may occur at arbitrary D2 in a full MSID but are allowed only with a2D2 = C2 A /2 in a partial MSID (CA is the Alfvn speed), while each case of |m | ? 1 gives two possible values of D2 for purely azimuthal propagations of fast and slow MHD density waves (FMDWs and SMDWs) that appear stationary in an inertial frame of reference. For disk galaxies modeled by a partial MSID resulting from a massive dark-matter halo with a flat rotation curve and a2D2 ? C2 A, stationary aligned perturbations of m = 1 are not allowed. For

Yu-qing Lou

2003-01-01T23:59:59.000Z

397

Laser illuminator and optical system for disk patterning  

SciTech Connect

Magnetic recording media are textured over areas designated for contact in order to minimize friction with data transducing heads. In fabricating a hard disk, an aluminum nickel-phosphorous substrate is polished to a specular finish. A mechanical means is then used to roughen an annular area intended to be the head contact band. An optical and mechanical system allows thousands of spots to be generated with each laser pulse, allowing the textured pattern to be rapidly generated with a low repetition rate laser and an uncomplicated mechanical system. The system uses a low power laser, a beam expander, a specially designed phase plate, a prism to deflect the beam, a lens to transmit the diffraction pattern to the far field, a mechanical means to rotate the pattern and a trigger system to fire the laser when sections of the pattern are precisely aligned. The system generates an annular segment of the desired pattern with which the total pattern is generated by rotating the optical system about its optic axis, sensing the rotational position and firing the laser as the annular segment rotates into the next appropriate position. This marking system can be integrated into a disk sputtering system for manufacturing magnetic disks, allowing for a very streamlined manufacturing process.

Hackel, L.A.; Dane, C.B.; Dixit, S.N.; Everett, M.; Honig, J.

2000-03-14T23:59:59.000Z

398

Disk-averaged Spectra & light-curves of Earth  

E-Print Network (OSTI)

We are using computer models to explore the observational sensitivity to changes in atmospheric and surface properties, and the detectability of biosignatures, in the globally averaged spectra and light-curves of the Earth. Using AIRS (Atmospheric Infrared Sounder) data, as input for atmospheric and surface properties, we have generated spatially resolved high-resolution synthetic spectra using the SMART radiative transfer model, for a variety of conditions, from the UV to the far-IR (beyond the range of current Earth-based satellite data). We have then averaged over the visible disk for a number of different viewing geometries to quantify the sensitivity to surface types and atmospheric features as a function of viewing geometry, and spatial and spectral resolution. These results have been processed with an instrument simulator to improve our understanding of the detectable characteristics of Earth-like planets as viewed by the first generation extrasolar terrestrial planet detection and characterization missions (Terrestrial Planet Finder/Darwin and Life finder). The wavelength range of our results are modelled over are applicable to both the proposed visible coronograph and mid-infrared interferometer TPF architectures. We have validated this model against disk-averaged observations by the Mars Global Surveyor Thermal Emission Spectrometer (MGS TES). This model was also used to analyze Earth-shine data for detectability of planetary characteristics and biosignatures in disk-averaged spectra.

G. Tinetti; V. S. Meadows; D. Crisp; W. Fong; N. Kiang; E. Fishbein; T. Velusamy; E. Bosc; M. Turnbull

2005-02-11T23:59:59.000Z

399

Star Cluster Populations in the Outer Disks of Nearby Galaxies  

E-Print Network (OSTI)

We present a Large Binocular Telescope (LBT) imaging study that characterizes the star cluster component of nearby galaxy outer disks (beyond the optical radius R_25). Expanding on the pilot project of Herbert-Fort et al. (2009), we present deep (~ 27.5 mag V-band point-source limiting magnitude) U- and V-band imaging of six galaxies: IC 4182, NGC 3351, NGC 4736, NGC 4826, NGC 5474, and NGC 6503. We find that the outer disk of each galaxy is populated with marginally-resolved star clusters with masses ~10^3 M_sun and ages up to ~ 1 Gyr (masses and ages are limited by the depth of our imaging and uncertainties are large given how photometry can be strongly affected by the presence or absence of a few stars in such low mass systems), and that they are typically found out to at least 2 R_25 but sometimes as far as 3 to 4 R_25- even beyond the apparent HI disk. The mean rate of cluster formation for 1 R_25<= R <= 1.5R_25 is at least one every ~2.5 Myr and the clusters are spatially correlated with the HI, m...

Herbert-Fort, Stphane; Moustakas, John; Di Paola, Andrea; Pogge, Richard W; Ragazzoni, Roberto

2012-01-01T23:59:59.000Z

400

Laser illuminator and optical system for disk patterning  

DOE Patents (OSTI)

Magnetic recording media are textured over areas designated for contact in order to minimize friction with data transducing heads. In fabricating a hard disk, an aluminum nickel-phosphorous substrate is polished to a specular finish. A mechanical means is then used to roughen an annular area intended to be the head contact band. An optical and mechanical system allows thousands of spots to be generated with each laser pulse, allowing the textured pattern to be rapidly generated with a low repetition rate laser and an uncomplicated mechanical system. The system uses a low power laser, a beam expander, a specially designed phase plate, a prism to deflect the beam, a lens to transmit the diffraction pattern to the far field, a mechanical means to rotate the pattern and a trigger system to fire the laser when sections of the pattern are precisely aligned. The system generates an annular segment of the desired pattern with which the total pattern is generated by rotating the optical system about its optic axis, sensing the rotational position and firing the laser as the annular segment rotates into the next appropriate position. This marking system can be integrated into a disk sputtering system for manufacturing magnetic disks, allowing for a very streamlined manufacturing process.

Hackel, Lloyd A. (Livermore, CA); Dane, C. Brent (Livermore, CA); Dixit, Shamasundar N. (Livermore, CA); Everett, Mathew (Pleasanton, CA); Honig, John (Livermore, CA)

2000-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "brakes front disk" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


401

AdS/QCD and Applications of Light-Front Holography  

SciTech Connect

Light-Front Holography leads to a rigorous connection between hadronic amplitudes in a higher dimensional anti-de Sitter (AdS) space and frame-independent light-front wavefunctions of hadrons in 3 + 1 physical space-time, thus providing a compelling physical interpretation of the AdS/CFT correspondence principle and AdS/QCD, a useful framework which describes the correspondence between theories in a modified AdS5 background and confining field theories in physical space-time. To a first semiclassical approximation, where quantum loops and quark masses are not included, this approach leads to a single-variable light-front Schroedinger equation which determines the eigenspectrum and the light-front wavefunctions of hadrons for general spin and orbital angular momentum. The coordinate z in AdS space is uniquely identified with a Lorentz-invariant coordinate {zeta} which measures the separation of the constituents within a hadron at equal light-front time. The internal structure of hadrons is explicitly introduced and the angular momentum of the constituents plays a key role. We give an overview of the light-front holographic approach to strongly coupled QCD. In particular, we study the photon-to-meson transition form factors (TFFs) F{sub M{gamma}}(Q{sup 2}) for {gamma}{gamma}* {yields} M using light-front holographic methods. The results for the TFFs for the {eta} and {eta}' mesons are also presented. Some novel features of QCD are discussed, including the consequences of confinement for quark and gluon condensates. A method for computing the hadronization of quark and gluon jets at the amplitude level is outlined.

Brodsky, Stanley J.; /SLAC /Southern Denmark U., CP3-Origins; Cao, Fu-Guang; /Massey U.; de Teramond, Guy F.; /Costa Rica U.

2012-02-16T23:59:59.000Z

402

Apparatus for characterizing the temporo-spatial properties of a dynamic fluid front and method thereof  

DOE Patents (OSTI)

Methods and apparatus are described for characterizing the temporal-spatial properties of a dynamic fluid front within a mold space while the mold space is being filled with fluid. A method includes providing a mold defining a mold space and having one or more openings into the mold space; heating a plurality of temperature sensors that extend into the mold space; injecting a fluid into the mold space through the openings, the fluid experiencing a dynamic fluid front while filling the mold space with the fluid; and characterizing temporal-spatial properties of the dynamic fluid front by monitoring a temperature of each of the plurality of heated temperature sensors while the mold space is being filled with the fluid. An apparatus includes a mold defining a mold space; one or more openings for introducing a fluid into the mold space and filling the mold space with the fluid, the fluid experiencing a dynamic fluid front while filling the mold space; a plurality of heated temperature sensors extending into the mold space; and a computer coupled to the plurality of heated temperature sensors for characterizing the temporal-spatial properties of the dynamic fluid front.

Battiste, Richard L. (Oak Ridge, TN)

2007-12-25T23:59:59.000Z

403

Upper and lower limits on the Crab pulsar's astrophysical parameters set from gravitational wave observations by LIGO: braking index and energy considerations  

E-Print Network (OSTI)

The Laser Interferometer Gravitational Observatory (LIGO) has recently reached the end of its fifth science run (S5), having collected more than a year worth of data. Analysis of the data is still ongoing but a positive detection of gravitational waves, while possible, is not realistically expected for most likely sources. This is particularly true for what concerns gravitational waves from known pulsars. In fact, even under the most optimistic (and not very realistic) assumption that all the pulsar's observed spin-down is due to gravitational waves, the gravitational wave strain at earth from all the known isolated pulsars (with the only notable exception of the Crab pulsar) would not be strong enough to be detectable by existing detectors. By August 2006, LIGO had produced enough data for a coherent integration capable to extract signal from noise that was weaker than the one expected from the Crab pulsar's spin-down limit. No signal was detected, but beating the spin-down limit is a considerable achievement for the LIGO Scientific Collaboration (LSC). It is customary to translate the upper limit on strain from a pulsar into a more astrophysically significant upper limit on ellipticity. Once the spin-down limit has been beaten, it is possible to release the constraint that all the spin-down is due to gravitational wave emission. A more complete model with diverse braking mechanisms can be used to set limits on several astrophysical parameters of the pulsar. This paper shows possible values of such parameters for the Crab pulsar given the current limit on gravitational waves from this neutron star.

Giovanni Santostasi

2008-07-16T23:59:59.000Z

404

DISK EVOLUTION IN THE THREE NEARBY STAR-FORMING REGIONS OF TAURUS, CHAMAELEON, AND OPHIUCHUS  

SciTech Connect

We analyze samples of Spitzer Infrared Spectrograph spectra of T Tauri stars in the Ophiuchus, Taurus, and Chamaeleon I star-forming regions, whose median ages lie in the <1-2 Myr range. The median mid-infrared spectra of objects in these three regions are similar in shape, suggesting, on average, similar disk structures. When normalized to the same stellar luminosity, the medians follow each other closely, implying comparable mid-infrared excess emission from the circumstellar disks. We use the spectral index between 13 and 31 {mu}m and the equivalent width of the 10 {mu}m silicate emission feature to identify objects whose disk configuration departs from that of a continuous, optically thick accretion disk. Transitional disks, whose steep 13-31 {mu}m spectral slope and near-IR flux deficit reveal inner disk clearing, occur with about the same frequency of a few percent in all three regions. Objects with unusually large 10 {mu}m equivalent widths are more common (20%-30%); they could reveal the presence of disk gaps filled with optically thin dust. Based on their medians and fraction of evolved disks, T Tauri stars in Taurus and Chamaeleon I are very alike. Disk evolution sets in early, since already the youngest region, the Ophiuchus core (L1688), has more settled disks with larger grains. Our results indicate that protoplanetary disks show clear signs of dust evolution at an age of a few Myr, even as early as approx1 Myr, but age is not the only factor determining the degree of evolution during the first few million years of a disk's lifetime.

Furlan, E. [NASA Astrobiology Institute, and Department of Physics and Astronomy, UCLA, 430 Portola Plaza, Los Angeles, CA 90095 (United States); Watson, Dan M.; McClure, M. K., E-mail: Elise.Furlan@jpl.nasa.go, E-mail: dmw@pas.rochester.ed, E-mail: manoj@pas.rochester.ed [Department of Physics and Astronomy, University of Rochester, Rochester, NY 14627 (United States)

2009-10-01T23:59:59.000Z

405

NEAR-INFRARED DETECTION OF A SUPER-THIN DISK IN NGC 891  

SciTech Connect

We probe the disk structure of the nearby, massive, edge-on spiral galaxy NGC 891 with subarcsecond resolution JHK{sub s}-band images covering {approx} {+-}10 kpc in radius and {+-}5 kpc in height. We measure intrinsic surface brightness (SB) profiles using realistic attenuation corrections constrained from near- and mid-infrared (Spitzer) color maps and three-dimensional Monte Carlo radiative-transfer models. In addition to the well-known thin and thick disks, a super-thin disk with 60-80 pc scale-height-comparable to the star-forming disk of the Milky Way-is visibly evident and required to fit the attenuation-corrected light distribution. Asymmetries in the super-thin disk light profile are indicative of young, hot stars producing regions of excess luminosity and bluer (attenuation-corrected) near-infrared color. To fit the inner regions of NGC 891, these disks must be truncated within {approx}3 kpc, with almost all their luminosity redistributed in a bar-like structure 50% thicker than the thin disk. There appears to be no classical bulge but rather a nuclear continuation of the super-thin disk. The super-thin, thin, thick, and bar components contribute roughly 30%, 42%, 13%, and 15% (respectively) to the total K{sub s}-band luminosity. Disk axial ratios (length/height) decrease from 30 to 3 from super-thin to thick components. Both exponential and sech{sup 2} vertical SB profiles fit the data equally well. We find that the super-thin disk is significantly brighter in the K{sub s}-band than typically assumed in integrated spectral energy distribution models of NGC 891: it appears that in these models the excess flux, likely produced by young stars in the super-thin disk, has been mistakenly attributed to the thin disk.

Schechtman-Rook, Andrew; Bershady, Matthew A., E-mail: andrew@astro.wisc.edu [Department of Astronomy, University of Wisconsin, 475 N. Charter Street, Madison, WI 53706 (United States)

2013-08-10T23:59:59.000Z

406

Measures of the Environmental Footprint of the Front End of the Nuclear Fuel Cycle  

SciTech Connect

Previous estimates of environmental impacts associated with the front end of the nuclear fuel cycle have focused primarily on energy consumption and CO2 emissions. Results have varied widely. Section 2 of this report provides a summary of historical estimates. This study revises existing empirical correlations and their underlying assumptions to fit to a more complete set of existing data. This study also addresses land transformation, water withdrawals, and occupational and public health impacts associated with the processes of the front end of the once-through nuclear fuel cycle. These processes include uranium mining, milling, refining, conversion, enrichment, and fuel fabrication. Metrics are developed to allow environmental impacts to be summed across the full set of front end processes, including transportation and disposition of the resulting depleted uranium.

Brett Carlsen; Emily Tavrides; Erich Schneider

2010-08-01T23:59:59.000Z

407

Light-front heavy-quark effective theory and heavy-meson bound states  

Science Journals Connector (OSTI)

The heavy-quark effective theory is developed on the light front. Based on this effective theory, a light-front heavy-meson bound state with definite spin and parity is constructed. Within the effective theory, the Isgur-Wise function is derived in terms of the asymptotic light-front bound state amplitudes in the limit mQ??; the result is a general expression for arbitrary recoil velocities. With the asymptotic form of the BSW amplitudes, the Isgur-Wise function is given by ?(v?v?)=1/v?v?. The slope at the zero-recoil point is ?2=-??(1)=1, in excellent agreement with the recent CLEO result of ?2=1.010.150.09.

Chi-Yee Cheung; Wei-Min Zhang; Guey-Lin Lin

1995-09-01T23:59:59.000Z

408

Detonative Propagation and Accelerative Expansion of the Crab Nebula Shock Front  

Science Journals Connector (OSTI)

The accelerative expansion of the Crab Nebulas outer envelope is a mystery in dynamics, as a conventional expanding blast wave decelerates when bumping into the surrounding interstellar medium. Here we show that the strong relativistic pulsar wind bumping into its surrounding nebula induces energy-generating processes and initiates a detonation wave that propagates outward to form the current outer edge, namely, the shock front, of the nebula. The resulting detonation wave, with a reactive downstream, then provides the needed power to maintain propagation of the shock front. Furthermore, relaxation of the curvature-induced reduction of the propagation velocity from the initial state of formation to the asymptotic, planar state of Chapman-Jouguet propagation explains the observed accelerative expansion. Potential richness in incorporating reactive fronts in the description of various astronomical phenomena is expected.

Yang Gao and Chung K. Law

2011-10-18T23:59:59.000Z

409

AdS/QCD and Light Front Holography: A New Approximation to QCD  

SciTech Connect

The combination of Anti-de Sitter space (AdS) methods with light-front holography leads to a semi-classical first approximation to the spectrum and wavefunctions of meson and baryon light-quark bound states. Starting from the bound-state Hamiltonian equation of motion in QCD, we derive relativistic light-front wave equations in terms of an invariant impact variable {zeta} which measures the separation of the quark and gluonic constituents within the hadron at equal light-front time. These equations of motion in physical space-time are equivalent to the equations of motion which describe the propagation of spin-J modes in anti-de Sitter (AdS) space. Its eigenvalues give the hadronic spectrum, and its eigenmodes represent the probability distribution of the hadronic constituents at a given scale. Applications to the light meson and baryon spectra are presented. The predicted meson spectrum has a string-theory Regge form M{sup 2} = 4{kappa}{sup 2}(n+L+S/2); i.e., the square of the eigenmass is linear in both L and n, where n counts the number of nodes of the wavefunction in the radial variable {zeta}. The space-like pion form factor is also well reproduced. One thus obtains a remarkable connection between the description of hadronic modes in AdS space and the Hamiltonian formulation of QCD in physical space-time quantized on the light-front at fixed light-front time {tau}. The model can be systematically improved by using its complete orthonormal solutions to diagonalize the full QCD light-front Hamiltonian or by applying the Lippmann-Schwinger method in order to systematically include the QCD interaction terms.

Brodsky, Stanley J.; de Teramond, Guy

2010-02-15T23:59:59.000Z

410

Compact ultrafast semiconductor disk laser: targeting GFP based nonlinear applications in living organisms  

Science Journals Connector (OSTI)

We present a portable ultrafast Semiconductor Disk Laser (SDL) (or vertical extended cavity surface emitting laserVECSELs), to be used for nonlinear microscopy. The SDL is...

Aviles-Espinosa, Rodrigo; Filippidis, George; Hamilton, Craig; Malcolm, Graeme; Weingarten, Kurt J; Sdmeyer, Thomas; Barbarin, Yohan; Keller, Ursula; Santos, Susana I C O; Artigas, David; Loza-Alvarez, Pablo

2011-01-01T23:59:59.000Z

411

Application of the Cubed-Sphere Grid to Tilted Black-Hole Accretion Disks  

SciTech Connect

In recent work we presented the first results of global general relativistic magnetohydrodynamic (GRMHD) simulations of tilted (or misaligned) accretion disks around rotating black holes. The simulated tilted disks showed dramatic differences from comparable untilted disks, such as asymmetrical accretion onto the hole through opposing 'plunging streams' and global precession of the disk powered by a torque provided by the black hole. However, those simulations used a traditional spherical-polar grid that was purposefully underresolved along the pole, which prevented us from assessing the behavior of any jets that may have been associated with the tilted disks. To address this shortcoming we have added a block-structured 'cubed-sphere' grid option to the Cosmos++ GRMHD code, which will allow us to simultaneously resolve the disk and polar regions. Here we present our implementation of this grid and the results of a small suite of validation tests intended to demonstrate that the new grid performs as expected. The most important test in this work is a comparison of identical tilted disks, one evolved using our spherical-polar grid and the other with the cubed-sphere grid. We also demonstrate an interesting dependence of the early-time evolution of our disks on their orientation with respect to the grid alignment. This dependence arises from the differing treatment of current sheets within the disks, especially whether they are aligned with symmetry planes of the grid or not.

Fragile, P C; Lindner, C C; Anninos, P; Salmonson, J D

2008-09-24T23:59:59.000Z

412

A rotating disk around the very young massive star AFGL 490  

E-Print Network (OSTI)

We observed the embedded, young 8--10 Msun star AFGL 490 at subarcsecond resolution with the Plateau de Bure Interferometer in the C17O (2--1) transition and found convincing evidence that AFGL 490 is surrounded by a rotating disk. Using two-dimensional modeling of the physical and chemical disk structure coupled to line radiative transfer, we constrain its basic parameters. We obtain a relatively high disk mass of 1 Msun and a radius of ~ 1500 AU. A plausible explanation for the apparent asymmetry of the disk morphology is given.

K. Schreyer; D. Semenov; Th. Henning; J. Forbrich

2006-01-12T23:59:59.000Z

413

E-Print Network 3.0 - accretion disk emission Sample Search Results  

NLE Websites -- All DOE Office Websites (Extended Search)

the accretion disk and the white dwarf) is irradiated and is a source of emission lines (Dhillon... lines originate primarily in an extended bright spot, with weaker emission...

414

E-Print Network 3.0 - accretion disk instability Sample Search...  

NLE Websites -- All DOE Office Websites (Extended Search)

Queen Mary, University of London Collection: Physics 29 Accretion Disk Evolution with Wind Infall II. Results of 3D Hydrodynamical Simulations with an Illustrative Application...

415

E-Print Network 3.0 - agn accretion-disk outflows Sample Search...  

NLE Websites -- All DOE Office Websites (Extended Search)

Jet NLR clouds BLR clouds 1 pc Accretion disk 12... .g., Reyolds & Nowak 2003) 2) The inclination ... Source: Evans, Daniel A. - Kavli Institute for Astrophysics and Space...

416

E-Print Network 3.0 - advection-dominated accretion disks Sample...  

NLE Websites -- All DOE Office Websites (Extended Search)

Universit Paris 7 Denis Diderot Collection: Physics 5 Accretion Disk Evolution with Wind Infall II. Results of 3D Hydrodynamical Simulations with an Illustrative Application...

417

E-Print Network 3.0 - accretion disks formed Sample Search Results  

NLE Websites -- All DOE Office Websites (Extended Search)

California Institute of Technology Collection: Physics 36 Accretion Disk Evolution With Wind Infall I. General Solution and Application to Sgr A* Summary: , slowly accreting,...

418

E-Print Network 3.0 - accretion disk structure Sample Search...  

NLE Websites -- All DOE Office Websites (Extended Search)

Physics Laboratory Collection: Plasma Physics and Fusion 27 Accretion Disk Evolution With Wind Infall I. General Solution and Application to Sgr A* Summary: and thus change the...

419

E-Print Network 3.0 - accretion disk spectra Sample Search Results  

NLE Websites -- All DOE Office Websites (Extended Search)

along the magnetic field lines (of stellar andor disk... an outflow (stellardisk wind) andor from the accreting columns. However, because of insufficient spectral......

420

E-Print Network 3.0 - agn accretion disks Sample Search Results  

NLE Websites -- All DOE Office Websites (Extended Search)

Accretion disk? (pc Rs) 12; Accretion flow surrounded by dusty torus BB... ) The inclination of the accretion ... Source: Evans, Daniel A. - Kavli Institute for...

Note: This page contains sample records for the topic "brakes front disk" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


421

The Non-Maxwellian Distribution in a Shock Front and the Anomaly of the Chromospheric Temperature  

Science Journals Connector (OSTI)

An estimate is made of the departure from the Maxwellian distribution of the particle velocities in a shock front, as a function of the shock strength. Expressions are derived for the absorption and emission coefficients (for electronic free-free transitions in a completely ionized gas) in a shock front of given strength. The results obtained are applied to resolve the apparent conflict between the two electronic temperatures of the chromosphere, as indicated by optical (30 000K from emission line widths) and radio (10 000K from centimetric radiation intensity) observations of the sun.

Hari K. Sen

1953-11-15T23:59:59.000Z

422

Transient nature of salt movement with wetting front in an unsaturated soil  

E-Print Network (OSTI)

TRANSIENT NATURE OF SALT MOVEMENT WITH WETTING FRONT IN AN UNSATURATED SOIL A Thesis bY VISHWAS VINAYAK SOMAN Submitted to the Office of Graduate Studies of Texas A&M UniversitY in partial fulfillment of the requirements for the degree... of MASTER OF SCIENCE August 1992 Major Subject: Agricultural Engineering TRANSIENT NATURE OF SALT MOVEMENT WITH WETTING FRONT IN AN UNSATURATED SOIL A Thesis VISHWAS VINAYAK SOMAN Approved as to style and content by: Marshall J. McFarland (Chair...

Soman, Vishwas Vinayak

1992-01-01T23:59:59.000Z

423

Nanoscale Graphene Disk: A Natural Functionally Graded Material --The Thermal Conductivity of Nanoscale Graphene Disk by Molecular Dynamics Simulation  

E-Print Network (OSTI)

In this letter, we investigate numerically (by non-equilibrium molecular dynamics) and analytically the thermal conductivity of nanoscale graphene disks (NGDs), and discussed the possibility to realize FGM with only one material, NGDs. We found that the NGD has a graded thermal conductivity and can be used as FGM in a large temperature range. Moreover, we show the dependent of NGDs' thermal conductivity on radius and temperature. Our study may inspire experimentalists to develop NGD based FGMs and help heat removal of hot spots on chips by graphene.

Yang, Nuo; Ma, Dengke; Lu, Tingyu; Li, Baowen

2014-01-01T23:59:59.000Z

424

REEXAMINATION OF INDUCTION HEATING OF PRIMITIVE BODIES IN PROTOPLANETARY DISKS  

SciTech Connect

We reexamine the unipolar induction mechanism for heating asteroids originally proposed in a classic series of papers by Sonett and collaborators. As originally conceived, induction heating is caused by the 'motional electric field' that appears in the frame of an asteroid immersed in a fully ionized, magnetized solar wind and drives currents through its interior. However, we point out that classical induction heating contains a subtle conceptual error, in consequence of which the electric field inside the asteroid was calculated incorrectly. The problem is that the motional electric field used by Sonett et al. is the electric field in the freely streaming plasma far from the asteroid; in fact, the motional field vanishes at the asteroid surface for realistic assumptions about the plasma density. In this paper we revisit and improve the induction heating scenario by (1) correcting the conceptual error by self-consistently calculating the electric field in and around the boundary layer at the asteroid-plasma interface; (2) considering weakly ionized plasmas consistent with current ideas about protoplanetary disks; and (3) considering more realistic scenarios that do not require a fully ionized, powerful T Tauri wind in the disk midplane. We present exemplary solutions for two highly idealized flows that show that the interior electric field can either vanish or be comparable to the fields predicted by classical induction depending on the flow geometry. We term the heating driven by these flows 'electrodynamic heating', calculate its upper limits, and compare them to heating produced by short-lived radionuclides.

Menzel, Raymond L.; Roberge, Wayne G., E-mail: menzer@rpi.edu, E-mail: roberw@rpi.edu [New York Center for Astrobiology and Department of Physics, Applied Physics and Astronomy, Rensselaer Polytechnic Institute, 110 8th Street, Troy, NY 12180 (United States)

2013-10-20T23:59:59.000Z

425

THE FREQUENCY OF DEBRIS DISKS AT WHITE DWARFS  

SciTech Connect

We present near- and mid-infrared photometry and spectroscopy from PAIRITEL, IRTF, and Spitzer of a metallicity-unbiased sample of 117 cool, hydrogen-atmosphere white dwarfs (WDs) from the Palomar-Green survey and find five with excess radiation in the infrared, translating to a 4.3{sup +2.7} {sub -1.2}% frequency of debris disks. This is slightly higher than, but consistent with the results of previous surveys. Using an initial-final mass relation, we apply this result to the progenitor stars of our sample and conclude that 1-7 M {sub Sun} stars have at least a 4.3% chance of hosting planets; an indirect probe of the intermediate-mass regime eluding conventional exoplanetary detection methods. Alternatively, we interpret this result as a limit on accretion timescales as a fraction of WD cooling ages; WDs accrete debris from several generations of disks for {approx}10 Myr. The average total mass accreted by these stars ranges from that of 200 km asteroids to Ceres-sized objects, indicating that WDs accrete moons and dwarf planets as well as solar system asteroid analogs.

Barber, Sara D.; Patterson, Adam J.; Kilic, Mukremin [Homer L. Dodge Department of Physics and Astronomy, University of Oklahoma, 440 W. Brooks St., Norman, OK 73019 (United States); Leggett, S. K. [Gemini Observatory, 670 N. A'ohoku Place, Hilo, HI 96720 (United States); Dufour, P. [Departement de Physique, Universite de Montreal, C.P. 6128, Succursale Centre-Ville, Montreal, Quebec H3C 3J7 (Canada); Bloom, J. S.; Starr, D. L., E-mail: barber@nhn.ou.edu [Department of Astronomy, University of California, Berkeley, CA 94720 (United States)

2012-11-20T23:59:59.000Z

426

Silicon Solar Cells with Front Hetero-Contact and Aluminum Alloy Back Junction: Preprint  

SciTech Connect

We prototype an alternative n-type monocrystalline silicon (c-Si) solar cell structure that utilizes an n/i-type hydrogenated amorphous silicon (a-Si:H) front hetero-contact and a back p-n junction formed by alloying aluminum (Al) with the n-type Si wafer.

Yuan, H.-C.; Page, M. R.; Iwaniczko, E.; Xu, Y.; Roybal, L.; Wang, Q.; Branz, H. M.; Meier, D. L.

2008-05-01T23:59:59.000Z

427

Average crack front velocity during subcritical fracture propagation in a heterogeneous medium  

E-Print Network (OSTI)

Average crack front velocity during subcritical fracture propagation in a heterogeneous medium relaxation tests, exploring subcritical to critical regimes. Transparency of the material (PMMA) allows kinetic crack propagation is usually referred to as sub-critical crack growth or sub- critical regime

Paris-Sud XI, Université de

428

Asymmetry of Tidal Plume Fronts in an Eastern Boundary Current Regime  

E-Print Network (OSTI)

water mass. This vorticity controls the transition of the tidal plume 2 #12;front to a subcritical state bulge, which in turn is embedded in far-field plume and coastal waters. Because of the mixing caused on its upwind or northern side) and marks a transition from supercritical to subcritical flow for 6

Jay, David

429

FORT HALL INDIAN RESERVATION PHONE (208) 239-4550 (Front Desk)  

E-Print Network (OSTI)

FORT HALL INDIAN RESERVATION PHONE (208) 239-4550 (Front Desk) or (208) 239-4551 FAX (208) 478 documents from the Shoshone Bannock Tribes point by point response (1 through 9)to ISRP review comments projects. Specific Points Technical Justification, Program Significance and consistency, and Project

430

report 2013 Front cover image: Greenough River Solar Farm, Western Australia.  

E-Print Network (OSTI)

. From jobs and investment in regional areas to solar panels, solar hot water and high efficiencyClean energy australia report 2013 #12;Front cover image: Greenough River Solar Farm, Western Australia. Courtesy of First Solar. #12;table of Contents 01 introduCtion 05 exeCutive summary 07 snapshot

Green, Donna

431

Geodesic Remeshing Using Front Propagation Gabriel Peyre (peyre@cmapx.polytechnique.fr)  

E-Print Network (OSTI)

Geodesic Remeshing Using Front Propagation Gabriel Peyr´e (peyre@cmapx.polytechnique.fr) CMAP modeling and processing that uses only fast geodesic computations. The basic building block, an intrinsic algo- rithm for computing geodesic centroidal tessellations, and a fast and robust method

Paris-Sud XI, Université de

432

Hierarchical Modelling of Automotive Sensor Front-Ends For Structural Diagnosis of Aging Faults  

E-Print Network (OSTI)

shown [2] that 41% of failures in automotive electronics could not be identified by functional diagnosisHierarchical Modelling of Automotive Sensor Front-Ends For Structural Diagnosis of Aging Faults h.g.kerkhoff@utwente.nl Abstract: The semiconductor industry for automotive applications is growing

Wieringa, Roel

433

Post-fire Erosion in the Colorado Front Range Lee H. MacDonald  

E-Print Network (OSTI)

Post-fire Erosion in the Colorado Front Range Lee H. MacDonald Department of Forest, Rangland and Watershed Stewardship Colorado State University, Fort Collins, CO 80523 Over the past few years there has been a large increase in the number of acres burned by wildfires in the western U.S. In addition

MacDonald, Lee

434

Linking drainage front morphology with gaseous diffusion in unsaturated porous media: A lattice Boltzmann study  

E-Print Network (OSTI)

porous media is analyzed using the lattice Boltzmann method LBM . Flow regimes for immiscible in a physical experiment such as a micromodel. In this study, we use the lattice Boltzmann method LBMLinking drainage front morphology with gaseous diffusion in unsaturated porous media: A lattice

Shor, Leslie McCabe

435

Lattice Boltzmann BGK simulation of non-linear sound waves: The development of a shock front  

E-Print Network (OSTI)

Lattice Boltzmann BGK simulation of non-linear sound waves: The development of a shock front J. M Boltzmann model to simulating non-linear propagative acoustic waves is considered. The lattice Boltzmann propagation at highReynolds numberis considered. These results suggest that the lattice Boltzmann model

Boyer, Edmond

436

A discontinuous Galerkin front tracking method for two-phase flows with surface tension  

E-Print Network (OSTI)

A discontinuous Galerkin front tracking method for two-phase flows with surface tension Vinh with surface tension. ? 2009 Elsevier Ltd. All rights reserved. 1. Introduction Interfaces separating regions tension. In this case, the interface separates two different fluids and the effect of surface tension re

Peraire, Jaime

437

A front-tracking algorithm for accurate representation of surface tension  

E-Print Network (OSTI)

A front-tracking algorithm for accurate representation of surface tension Stephane Popinet particularly, we focus our attention on obtaining an accurate description of the surface-tension terms and the associated pressure jump. We consider the stationary Laplace solution for a bub- ble with surface tension

Frey, Pascal

438

Toto the Robot Figure 1. Toto, front view. Figure 2. Toto, rear view.  

E-Print Network (OSTI)

Toto the Robot Figure 1. Toto, front view. Figure 2. Toto, rear view. Toto the Robot was created so in the back to allow the tape- recorder to be held inside, and the figure was spray-painted. With his metallic a robot, helps account for his lack of verbal charm. Second, some younger children may recognize in Toto

Indiana University

439

CSCI 3060U/ENGR 3980U -Winter 2013 Course Project Assignment #1 -Front End Requirements  

E-Print Network (OSTI)

and in true XP fashion represent those requirements as a set of requirements tests. Create and organize a complete set of requirements tests for the Front End of the Ticket Selling Service, to test for every required behaviour. Do not write any programs yet. Each test should be a complete test session input stream

Bradbury, Jeremy S.

440

OPTIMIZING MUON CAPTURE AND TRANSPORT FOR A NEUTRINO FACTORY/MUON COLLIDER FRONT END  

E-Print Network (OSTI)

OPTIMIZING MUON CAPTURE AND TRANSPORT FOR A NEUTRINO FACTORY/MUON COLLIDER FRONT END Hisham K In the current baseline scheme of the Neutrino Fac- tory/Muon Collider a muon beam from pion decay is pro- duced of the field along the beam, were varied to maximize the number of muons delivered to the Cooling Channel

McDonald, Kirk

Note: This page contains sample records for the topic "brakes front disk" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


441

Fronts in the Southwestern Gulf of Maine5 Nicholas W. Woods1,2  

E-Print Network (OSTI)

Autonomous Systems Laboratory,12 Physical Oceanography Department13 Woods Hole Oceanographic Institution14 15, and autonomous underwater glider observations. Density fronts are found throughout47 the southwestern GOM during inversely upon the time-integrated regional wind stress magnitude and49 the rate of river discharge

Fratantoni, David

442

ICE Professionals Limited Email: dean@theicebase.com Ph: (09) 557 1450 Front End Developer  

E-Print Network (OSTI)

ICE Professionals Limited Email: dean@theicebase.com Ph: (09) 557 1450 Front End Developer, this is the job for you. Responsibilities: Producing high quality HTML/CSS and JavaScript solutions. Providing to produce dynamic pages If you are interested in this role, send your CV and academic transcript to Dean

Sun, Jing

443

CIAO-HELLO information Centre Helpdesk, front office, person-to-person interaction  

E-Print Network (OSTI)

CIAO-HELLO information Centre Helpdesk, front office, person-to-person interaction and welcome to foreign students 5th Erasmus Staff Mobility Week 2014 Rome 23rd - 27th, June 2014 #12;CIAO-HELLO of student experience exchanges A rise in the international scenario at Sapienza Pagina 224/06/2014CIAO-HELLO

Di Pillo, Gianni

444

The Influence of Canyon Winds on Flow Fields near Colorado's Front Range  

Science Journals Connector (OSTI)

A network of sodars was operated in the late summer and fall of 1993 to monitor the occurrence of nocturnal winds from a canyon in Colorado's Front Range near the Rocky Flats Plant and to determine the influence of those winds on the flow fields ...

J. C. Doran

1996-04-01T23:59:59.000Z

445

The Energy Spectrum of Fronts: Time Evolution of Shocks in Burgers Equation  

Science Journals Connector (OSTI)

Andrews and Hoskins used semigeostrophic theory to argue that the energy spectrum of a front should decay like the ?8/3 power of the wavenumber. They note, however, that their inviscid analysis is restricted to the very moment of breaking; that ...

John P. Boyd

1992-01-01T23:59:59.000Z

446

Export of Asian pollution during two cold front episodes of the TRACE-P experiment  

E-Print Network (OSTI)

of the Asian outflow by fragmenting the pollution plume. INDEX TERMS: 0365 Atmospheric Composition and Atmospheric Dynamics: Mesoscale meteorology; KEYWORDS: warm conveyor belt, TRACE-P, pollution Citation: MariExport of Asian pollution during two cold front episodes of the TRACE-P experiment C. Mari

Palmer, Paul

447

RESEARCH ARTICLES Genetic Assessment of a White-Collared Red-Fronted  

E-Print Network (OSTI)

RESEARCH ARTICLES Genetic Assessment of a White-Collared ? Red-Fronted Lemur Hybrid Zone examined a purported lemur (Eulemur fulvus rufus ? E. albocollaris) hybrid zone at Andringitra, Madagascar. albocollaris (n = 16), E.f. rufus (n = 14), E. collaris (n = 9), and purported hybrids from Andringitra (n = 21

DeSalle, Rob

448

Anisotropy in growth-front roughening Y.-P. Zhao, G.-C. Wang, and T.-M. Lu  

E-Print Network (OSTI)

Anisotropy in growth-front roughening Y.-P. Zhao, G.-C. Wang, and T.-M. Lu Department of Physics physical processes, evaporation/condensation and surface diffusion, to describe the roughening consider the effect of growth-front roughening due to the anisotropy in surface diffusion barrier Schwoebel

Wang, Gwo-Ching

449

Dynamics and ecological consequences of avian influenza virus infection in greater white-fronted geese in their winter staging areas  

Science Journals Connector (OSTI)

...indicates the centre of a 5 km distance class. Grey bar, AI negative; black bar...of avian influenza virus infection in greater white-fronted geese in their winter...we link capture-resighting data of greater white-fronted geese Anser albifrons...

2010-01-01T23:59:59.000Z

450

DRPM: Dynamic Speed Control for Power Management in Server Class Disks Sudhanva Gurumurthi  

E-Print Network (OSTI)

[5] that power densities of data centers could grow to over 100 Watts per square foot and that the caDRPM: Dynamic Speed Control for Power Management in Server Class Disks Sudhanva Gurumurthi portion of the power budget in server environ- ments goes into the I/O subsystem - the disk array in par

Sivasubramaniam, Anand

451

Dynamic Speed Control for Server Class Disks Sudhanva Gurumurthi Anand Sivasubramaniam Mahmut Kandemir  

E-Print Network (OSTI)

been observed [5] that power densities of data centers could grow to over 100 Watts per square foot Abstract A large portion of the power budget in server environments goes into the I/O subsystem - the disk array in particular. Traditional approaches to disk power management involve completely stopping

Gurumurthi, Sudhanva

452

ApJ, accepted 16 March 1999 A 1000 AU Rotating Disk around the  

E-Print Network (OSTI)

a luminosity #24; 3 #2; 10 3 L#12; which implies the presence of a mid to early B star (Shepherd & Churchwell.16 3.82 D.S. Shepherd 1 & S. E. Kurtz 2 ABSTRACT We present evidence for a circumstellar disk around exists around the central B2 star. The disk major axis is roughly perpendicular to the out ow

Shepherd, Debra

453

The Conquest File System: Better Performance Through a Disk/Persistent-RAM Hybrid Design  

E-Print Network (OSTI)

memory, except providing large storage capacity. Unlike caching, Conquest uses memory with battery backup storage capacity is advancing at a rapid rate, the mechanical latency of disk has improved only at 15% per as persistent storage, and provides specialized and separate data paths to memory and disk. Therefore

Wang, Andy

454

Distributed Mobile Disk Cover A Building Block for Mobile Backbone Networks  

E-Print Network (OSTI)

1 Distributed Mobile Disk Cover ­ A Building Block for Mobile Backbone Networks Anand Srinivas, Gil of Mobile Backbone Networks has been recently studied by a few different approaches. An important subproblem a Geometric Disk Cover (GDC) under mobility. While from the context of static nodes and centralized solutions

Zussman, Gil

455

GRAVITATIONAL DRAG ON A POINT MASS IN HYPERSONIC MOTION WITHIN A GAUSSIAN DISK  

SciTech Connect

We develop an analytical model for the accretion and gravitational drag on a point mass that moves hypersonically in the midplane of a gaseous disk with a Gaussian vertical density stratification. Such a model is of interest for studying the interaction between a planet and a protoplanetary disk, as well as the dynamical decay of massive black holes in galactic nuclei. The model assumes that the flow is ballistic, and gives fully analytical expressions for both the accretion rate onto the point mass and the gravitational drag it suffers. The expressions are further simplified by taking the limits of a thick and of a thin disk. The results for the thick disk reduce correctly to those for a uniform density environment. We find that for a thin disk (small vertical scaleheight compared to the gravitational radius), the accretion rate is proportional to the mass of the moving object and to the surface density of the disk, while the drag force is independent of the velocity of the object. The gravitational deceleration of the hypersonic perturber in a thin disk was found to be independent of its parameters (i.e., mass or velocity) and depends only on the surface mass density of the disk. The predictions of the model are compared to the results of three-dimensional hydrodynamical simulations, with reasonable agreement.

Canto, J.; Sanchez-Salcedo, F. J. [Instituto de Astronomia, Universidad Nacional Autonoma de Mexico, Ap. 70-468, 04510 D.F. (Mexico)] [Instituto de Astronomia, Universidad Nacional Autonoma de Mexico, Ap. 70-468, 04510 D.F. (Mexico); Esquivel, A.; Raga, A. C., E-mail: jsanchez@astro.unam.mx, E-mail: esquivel@nucleares.una.mx, E-mail: raga@nucleares.unam.mx [Instituto de Ciencias Nucleares, Universidad Nacional Autonoma de Mexico, Apartado Postal 70-543, 04510 Mexico D.F. (Mexico)

2013-01-01T23:59:59.000Z

456

Accretion Disk Evolution With Wind Infall I. General Solution and Application to Sgr A*  

E-Print Network (OSTI)

The evolution of an accretion disk can be influenced significantly by the deposition of mass and angular momentum by an infalling Bondi-Hoyle wind. Such a mass influx impacts the long-term behavior of the disk by providing additional sources of viscosity and heating. In this paper, we derive and solve the disk equations when these effects are taken into account. We present a survey of models with various wind configurations and demonstrate that the disk spectrum may then differ substantially from that of a standard alpha-disk. In particular, it is likely that a wind-fed disk has a significant infrared bump due to the deposition of energy in its outer region. We apply some of the results of our calculations to the Galactic Center black hole candidate Sgr A* and show that if a fossil disk is present in this source, it must have a very low viscosity parameter (alpha<10^-4) and the Bondi-Hoyle wind must be accreting with a very high specific angular momentum to prevent it from circularizing in the inner disk region where its impact would be most noticeable.

Heino Falcke; Fulvio Melia

1996-11-12T23:59:59.000Z

457

arXiv:astro-ph/0508261v111Aug2005 THE OPACITY OF SPIRAL GALAXY DISKS  

E-Print Network (OSTI)

Figure 2 shows the stacked radial opacity profile of our entire sample of 32 HST/WFPC2 fields. FromarXiv:astro-ph/0508261v111Aug2005 THE OPACITY OF SPIRAL GALAXY DISKS Dust opacity from calibrated Abstract The opacity of foreground spiral disks can be probed from the number of distant galaxies seen

Kruit, Piet van der

458

Deep Spitzer spectroscopy of the `Flying Saucer' edge-on disk: Large grains beyond 50 AU  

E-Print Network (OSTI)

We present deep Spitzer-IRS low-resolution (lambda/Delta lambda ~ 100) 5-35 micron spectroscopy of the edge-on disk ``the Flying Saucer'' (2MASS J16281370-2431391) in the Ophiuchus molecular cloud. The spectral energy distribution exhibits the characteristic two-peak shape predicted for a circumstellar disk viewed very close to edge-on. The short-wavelength peak is entirely due to photons scattered off the surface of the disk, while the long-wavelength peak is due to thermal emission from the disk itself. The Spitzer spectrum represents the first spectroscopic detection of scattered light out to 15 micron from a bona-fide, isolated edge-on disk around a T Tauri star. The depth and the wavelength of the mid-infrared "valley" of the SED give direct constraints on the size distribution of large grains in the disk. Using a 2D continuum radiative transfer model, we find that a significant amount of 5-10 micron-sized grains is required in the surface layers of the disk at radii of 50-300 AU. The detection of relatively large grains in the upper layers implies that vertical mixing is effective, since grain growth models predict the grains would otherwise settle deep in the disk on short time scales. Additionally, we tentatively detect the 9.66 micron S(3) line of H2 and the 11.2 micron emission feature due to PAHs.

Klaus M. Pontoppidan; Karl R. Stapelfeldt; Geoffrey A. Blake; Ewine F. van Dishoeck; Cornelis P. Dullemond

2007-02-14T23:59:59.000Z

459

ZnO Nanostructures Single-Crystal Hexagonal Disks and Rings of  

E-Print Network (OSTI)

ZnO Nanostructures Single-Crystal Hexagonal Disks and Rings of ZnO: Low-Temperature, Large of Chemistry University of New Orleans New Orleans, LA 70148 (USA) Fax: (+1)504-280-6860 E-mail: fli@uno.edu Dr to ellipsoids to disks, and even much more complex shapes, by adjusting experimental parameters,[33] we can

Wang, Zhong L.

460

Dynamics of air bearing sliders flying on partially planarized bit patterned media in hard disk drives  

Science Journals Connector (OSTI)

Bit patterned media (BPM) recording is one of the promising techniques for future disk drives in order to increase the areal density above 1Tbit/in2. However, the BPM can change the topography of the disk surface and thus have an effect ...

Liping Li; David B. Bogy

2011-06-01T23:59:59.000Z

Note: This page contains sample records for the topic "brakes front disk" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


461

Structural modal interaction of a four degree of freedom bladed disk and casing model  

E-Print Network (OSTI)

Structural modal interaction of a four degree of freedom bladed disk and casing model Mathias specific interaction phenomenon that may occur in turbo- machines due to radial rub between a bladed disk requirements leading to reduced clearance between blade-tips and casing together with the rotation of the blade

Boyer, Edmond

462

Model reduction applied to multi-stage assemblies of bladed disks  

E-Print Network (OSTI)

consisted in modelling separately each stage of the assembly of bladed disks that compose the rotor of a jetModel reduction applied to multi-stage assemblies of bladed disks A. Sternch¨uss, E. Balm, France e-mail: arnaud.sternchuss@ecp.fr P. Jean, J.-P. Lombard Snecma (Safran Group) Rond-point Ren

Boyer, Edmond

463

Energy-Aware Prefetching for Parallel Disk Systems Algorithms, Models, and Evaluation  

E-Print Network (OSTI)

system grows, the energy consumed by the I/O system often becomes a large part of the total cost significantly reduce energy consumption in parallel disk systems by up to 50 percent. In addition, we of ownership [16]. Reducing the energy costs of operating these large-scale disk I/O systems often becomes one

Qin, Xiao

464

Probing the electronic structure and optical response of a graphene quantum disk supported on monolayer graphene  

E-Print Network (OSTI)

Probing the electronic structure and optical response of a graphene quantum disk supported on monolayer graphene This article has been downloaded from IOPscience. Please scroll down to see the full text.1088/0953-8984/24/31/314213 Probing the electronic structure and optical response of a graphene quantum disk supported on monolayer

Pennycook, Steve

465

HIGH-CONTRAST NEAR-INFRARED IMAGING POLARIMETRY OF THE PROTOPLANETARY DISK AROUND RY TAU  

SciTech Connect

We present near-infrared coronagraphic imaging polarimetry of RY Tau. The scattered light in the circumstellar environment was imaged at the H band at a high resolution ({approx}0.''05) for the first time, using Subaru/HiCIAO. The observed polarized intensity (PI) distribution shows a butterfly-like distribution of bright emission with an angular scale similar to the disk observed at millimeter wavelengths. This distribution is offset toward the blueshifted jet, indicating the presence of a geometrically thick disk or a remnant envelope, and therefore the earliest stage of the Class II evolutionary phase. We perform comparisons between the observed PI distribution and disk models with (1) full radiative transfer code, using the spectral energy distribution (SED) to constrain the disk parameters; and (2) monochromatic simulations of scattered light which explore a wide range of parameters space to constrain the disk and dust parameters. We show that these models cannot consistently explain the observed PI distribution, SED, and the viewing angle inferred by millimeter interferometry. We suggest that the scattered light in the near-infrared is associated with an optically thin and geometrically thick layer above the disk surface, with the surface responsible for the infrared SED. Half of the scattered light and thermal radiation in this layer illuminates the disk surface, and this process may significantly affect the thermal structure of the disk.

Takami, Michihiro; Karr, Jennifer L.; Kim, Hyosun; Chou, Mei-Yin [Institute of Astronomy and Astrophysics, Academia Sinica. P.O. Box 23-141, Taipei 10617, Taiwan (China); Hashimoto, Jun; Kandori, Ryo; Kusakabe, Nobuhiko; Kwon, Jungmi [National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588 (Japan); Wisniewski, John [H. L. Dodge Department of Physics and Astronomy, University of Oklahoma, 440 West Brooks Street, Norman, OK 73019 (United States); Henning, Thomas; Brandner, Wolfgang [Max Planck Institute for Astronomy, Koenigstuhl 17, D-69117 Heidelberg (Germany); Grady, Carol A. [Eureka Scientific, 2452 Delmer, Suite 100, Oakland, CA 96002 (United States); Hodapp, Klaus W. [Institute for Astronomy, University of Hawaii, 640 North A'ohoku Place, Hilo, HI 96720 (United States); Kudo, Tomoyuki [Subaru Telescope, 650 North A'ohoku Place, Hilo, HI 96720 (United States); Itoh, Yoichi [Nishi-Harima Astronomical Observatory, Center for Astronomy, University of Hyogo, 407-2 Nishigaichi, Sayo, Hyogo 679-5313 (Japan); Momose, Munetake [College of Science, Ibaraki University, 2-1-1 Bunkyo, Mito, Ibaraki 310-8512 (Japan); Mayama, Satoshi [The Center for the Promotion of Integrated Sciences, The Graduate University for Advanced Studies (SOKENDAI), Shonan International Village, Hayama-cho, Miura-gun, Kanagawa 240-0193 (Japan); Currie, Thayne [Department of Astronomy and Astrophysics, University of Toronto, Toronto, ON (Canada); Follette, Katherine B. [Steward Observatory, University of Arizona, 933 North Cherry Avenue, Tucson AZ 85721 (United States); Abe, Lyu, E-mail: hiro@asiaa.sinica.edu.tw [Laboratoire Lagrange (UMR 7293), Universite de Nice-Sophia Antipolis, CNRS, Observatoire de la Cote d'Azur, 28 Avenue Valrose, F-06108 Nice Cedex 2 (France); and others

2013-08-01T23:59:59.000Z

466

An evaluation of the storage systems based on network-attached disks  

E-Print Network (OSTI)

show that (a) The advantages of distributing the server's network processing workload to disks may be offset by the decreased cache hit ratios in a file system based on network-attached disks. (b) Performance can be significantly improved in a Web...

Ma, Gang

1998-01-01T23:59:59.000Z

467

Nano-compact disks with 400 Gbit/in2 storage density fabricated  

E-Print Network (OSTI)

Nano-compact disks with 400 Gbit/in2 storage density fabricated using nanoimprint lithography and read with proximal probe Peter R. Kraussa) and Stephen Y. Choub) NanoStructure Laboratory, Department for publication 30 September 1997 Nano-compact disks Nano-CDs with 400 Gbit/in2 topographical bit density nearly

468

The influence of convective heat transfer on flow stability in rotating disk chemical vapor deposition reactors  

SciTech Connect

Flow and heat transfer of NH{sub 3} and He were studied in a rotating disk system with applications to chemical vapor deposition reactors. Flow field and disk heat flux were obtained over a range of operating conditions. Comparisons of disk convective heat transfer were made to infinite rotating disk results to appraise uniformity of transport to the disk. Important operating variables include disk spin rate, disk and enclosure temperatures, flow rate, composition, pressure, and gas mixture temperature at the reactor inlet. These variables were studied over ranges of the spin Reynolds number, Re{omega}; disk mixed convection parameter, MCP{sub w}; and wall mixed convection parameter, MCP{sub w}. Results obtained for NH{sub 3} show that increasing Re{omega} from 314.5 to 3145 increases the uniformity of rotating disk heat flux and results in thinner thermal boundary layers at the disk surface. At Re{omega}=314.5, increasing MCP{sub d} to 15 leads to significant departure from the infinite disk result with nonuniform disk heat fluxes and recirculating flow patterns; flow becomes increasingly complex at larger values of MCP{sub d}. At Re{omega} of 3145, results are closer to the infinite disk for MCP{sub d} up to 15. For large negative (hot walls) and positive (cold walls) values of MCP{sub w}, flow recirculates and there is significant deviation from the infinite disk result; nonuniformities occur at both values of Re{omega}. The influence of MCP{sub w} on flow stability is increased at larger MCP{sub d} and lower Re{omega}. To determine the influence of viscosity and thermal conductivity variation with temperature, calculations were made with He and NH{sub 3}; He transport property variation is low relative to NH{sub 3}. Results show that the flow of NH{sub 3} is less stable than that of He as MCP{sub d} is increased for MCP{sub w}=0 and Re{omega}=314.5. 16 refs., 15 figs., 1 tab.

Winters, W.S.; Evans, G.H. [Sandia National Labs., Livermore, CA (United States); Grief, R. [Univ. of California, Berkeley, CA (United States). Mechanical Engineering Dept.

1997-06-01T23:59:59.000Z

469

Precession of neutrino-cooled accretion disks in gamma-ray burst engines  

E-Print Network (OSTI)

We study the precession of accretion disks in the context of gamma-ray burst inner engines. With an accretion disk model that allows for neutrino cooling, we evaluate the possible periods of disk precession and nutation due to the Lense-Thirring effect. Assuming jet ejection perpendicular to the disk midplane and a typical intrinsic time dependence for the burst, we find possible gamma-ray light curves with temporal microstructure similar to what is observed in some subsamples. We conclude that the precession and nutation of a neutrino-cooled accretion disk in the burst engine might be responsible for some events, especially those with a slow rise and a fast decay.

Matias M. Reynoso; Gustavo E. Romero; Oscar A. Sampayo

2006-07-14T23:59:59.000Z

470

Residual stress profiles for mitigating fretting fatigue in gas turbine engine disks  

Science Journals Connector (OSTI)

The driving force for fretting fatigue in engine disks is the contact stresses generated by fretting of the blade and the disk surfaces in the attachment region. This paper examines the use of different residual compressive stress profiles to counteract the undesirable effects of contact stresses and to mitigate fretting fatigue. A global finite-element analysis of the disk blade assembly is first performed. The contact pressure and shear traction at the attachment region are extracted from the FEM results and used to compute the contact stress distribution. The contact stresses are then combined with the residual stresses and the bulk stresses. The overall stress distribution is then utilized in a probabilistic crack growth model to predict the risk of disk failure for a military engine under simulated loading conditions. The results are used to identify the minimum residual stress profile for mitigating fretting fatigue in engine disks.

Kwai S. Chan; Michael P. Enright; Jonathan P. Moody; Patrick J. Golden; Ramesh Chandra; Alan C. Pentz

2010-01-01T23:59:59.000Z

471

A gap capacitance method for slider flying height measurement in near-field optical disk drives  

Science Journals Connector (OSTI)

In order to overcome the diffraction limit of conventional optical disk drives, and substantially increase data storage capacity and density, near-field optical disk drives remain to be realized. The slider of a flying pickup head in a near-field optical disk drive has to fly at a stable spacing above the disk surface. To sense the slider flying height, a gap capacitance method is developed in this study to measure capacitance variation between the pickup head and disk surface. The capacitance varying with the flying height is modulated by a Colpitts oscillator. Subsequent demodulation accounts for height variation of the flying pickup head. Measurement results of this method are verified by using a laser Doppler interferometer.

J.W. Chen; T.S. Liu

2004-01-01T23:59:59.000Z

472

Cooling a Hot Disk Around a Supermassive Black Hole by a Star  

E-Print Network (OSTI)

If a supermassive black hole resides in the centers of galaxies, there are several effects expected to be observed. It is likely that accretion disks are around the supermassive black hole. Stellar interactions with the accretion flows around the supermassive black hole play a role in that an flying-by star may cool a hot accretion disk as a result of Comptonization. It is shown that the Comptonization of the stellar emission will take place in a hot accretion disk such as the ADAFs around the supermassive black hole and become a relatively important source of the accretion disk cooling when the mass accretion rate is low, and stars are passing outer parts of the hot accretion disk. We suggest that such a stellar cooling can be observed in the radio frequency regime since synchrotron luminosity of the ADAFs depends strongly on the electron temperature and occurs much more frequently than a tidal disruption event.

Chang, H Y

2000-01-01T23:59:59.000Z

473

Cooling a Hot Disk Around a Supermassive Black Hole by a Star  

E-Print Network (OSTI)

If a supermassive black hole resides in the centers of galaxies, there are several effects expected to be observed. It is likely that accretion disks are around the supermassive black hole. Stellar interactions with the accretion flows around the supermassive black hole play a role in that an flying-by star may cool a hot accretion disk as a result of Comptonization. It is shown that the Comptonization of the stellar emission will take place in a hot accretion disk such as the ADAFs around the supermassive black hole and become a relatively important source of the accretion disk cooling when the mass accretion rate is low, and stars are passing outer parts of the hot accretion disk. We suggest that such a stellar cooling can be observed in the radio frequency regime since synchrotron luminosity of the ADAFs depends strongly on the electron temperature and occurs much more frequently than a tidal disruption event.

Heon-Young Chang

2000-12-18T23:59:59.000Z

474

Lenticular galaxy IC 719: current building of the counterrotating large-scale stellar disk  

E-Print Network (OSTI)

We have obtained and analyzed long-slit spectral data for the lenticular galaxy IC 719. In this gas-rich S0 galaxy, its large-scale gaseous disk counterrotates the global stellar disk. Moreover in the IC 719 disk we have detected a secondary stellar component corotating the ionized gas. By using emission-line intensity ratios, we have proved the gas excitation by young stars and so are claiming current star formation, most intense in a ring-like zone at the radius of 10" (1.4 kpc). The oxygen abundance of the gas in the starforming ring is about half of the solar abundance. Since the stellar disk remains dynamically cool, we conclude that smooth prolonged accretion of the external gas from a neighboring galaxy provides urrent building of the thin large-scale stellar disk.

Katkov, Ivan Yu; Afanasiev, Victor L

2013-01-01T23:59:59.000Z

475

Gas-phase CO in protoplanetary disks: a challenge for turbulent mixing  

E-Print Network (OSTI)

This is the first paper in a series where we study the influence of turbulent diffusion and advective transport on the chemical evolution of protoplanetary disks, using a 2D flared disk model and a 2D mixing gas-grain chemical code with surface reactions. A first interesting result concerns the abundance of gas-phase CO in the outer regions of protoplanetary disks. In this Letter we argue that the gas-phase CO concentration in the disk regions, where the temperature is lower than $\\sim25$ K, can be significantly enhanced due to the combined effect of vertical and radial mixing. This finding has a potential implication for the current observational data on the DM~Tau disk chemistry.

D. Semenov; D. Wiebe; Th. Henning

2006-07-02T23:59:59.000Z

476

Air Entrapment in Nanometer-Thick Lubricant Films and its Effect on Slider Flying Height in a Hard Disk Drive  

Science Journals Connector (OSTI)

Experimental data are presented, showing that the flying height of a slider in a hard disk drive can be altered by the chemical ... of the molecularly-thin lubricant film on the disk surface. It is suggested that...

B. Marchon; X. C. Guo; S. Canchi; R. H. Wang; N. Supper; J. Burns

2012-09-01T23:59:59.000Z

477

Investigation of wear resistance and lifetime of diamond-like carbon (DLC) coated glass disk in flying height measurement process  

Science Journals Connector (OSTI)

Flying height has been greatly reduced to less ... -density magnetic storage. This leads to significant disk wear especially, glass disks used in flying height measurement process. This paper reports the ... the ...

Korakoch Phetdee; Alongkorn Pimpin; Werayut Srituravanich

2011-08-01T23:59:59.000Z

478

Thin film gas lubrication characteristics of flying head slider bearings over patterned media in hard disk drives  

Science Journals Connector (OSTI)

...? This paper describes the effects of moving patterned disk surfaces on thin film gas lubrication characteristics for flying head slider bearings in magnetic hard disk drives. In order to perform the most real...

N. Tagawa; A. Mori

2003-05-01T23:59:59.000Z

479

Real-Time Parallel Disk Scheduling for VBR Video Servers Ozgur Ertu g Mahesh Kallahalla Peter J. Varman  

E-Print Network (OSTI)

the potential to alleviate this problem by providing a higher disk bandwidth. However harnessing the raw disk J. Varman Department of Electrical and Computer Engineering Rice University Houston TX 77251

Mellor-Crummey, John

480

VERTICAL STRUCTURE OF STATIONARY ACCRETION DISKS WITH A LARGE-SCALE MAGNETIC FIELD  

SciTech Connect

In earlier works we pointed out that the disk's surface layers are non-turbulent and thus highly conducting (or non-diffusive) because the hydrodynamic and/or magnetorotational instabilities are suppressed high in the disk where the magnetic and radiation pressures are larger than the plasma thermal pressure. Here, we calculate the vertical profiles of the stationary accretion flows (with radial and azimuthal components), and the profiles of the large-scale, magnetic field taking into account the turbulent viscosity and diffusivity and the fact that the turbulence vanishes at the surface of the disk. Also, here we require that the radial accretion speed be zero at the disk's surface and we assume that the ratio of the turbulent viscosity to the turbulent magnetic diffusivity is of order unity. Thus, at the disk's surface there are three boundary conditions. As a result, for a fixed dimensionless viscosity {alpha}-value, we find that there is a definite relation between the ratio R of the accretion power going into magnetic disk winds to the viscous power dissipation and the midplane plasma-{beta}, which is the ratio of the plasma to magnetic pressure in the disk. For a specific disk model with R of order unity we find that the critical value required for a stationary solution is {beta}{sub c} Almost-Equal-To 2.4r/({alpha}h), where h is the disk's half thickness. For weaker magnetic fields, {beta} > {beta}{sub c}, we argue that the poloidal field will advect outward while for {beta} < {beta}{sub c} it will advect inward. Alternatively, if the disk wind is negligible (R<<1), there are stationary solutions with {beta} >> {beta}{sub c}.

Bisnovatyi-Kogan, G. S. [Space Research Institute, Russian Academy of Sciences, Moscow (Russian Federation); Lovelace, R. V. E., E-mail: gkogan@mx.iki.rssi.ru, E-mail: RVL1@cornell.edu [Department of Astronomy, Cornell University, Ithaca, NY 14853-6801 (United States)

2012-05-10T23:59:59.000Z

Note: This page contains sample records for the topic "brakes front disk" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


481

On the aerodynamic redistribution of chondrite components in protoplanetary disks  

E-Print Network (OSTI)

Despite being all roughly of solar composition, primitive meteorites (chondrites) present a diversity in their chemical, isotopic and petrographic properties, and in particular a first-order dichotomy between carbonaceous and non-carbonaceous chondrites. We investigate here analytically the dynamics of their components (chondrules, refractory inclusions, metal/sulfide and matrix grains) in protoplanetary disks prior to their incorporation in chondrite parent bodies. We find the dynamics of the solids, subject to gas drag, to be essentially controlled by the "gas-solid decoupling parameter" $S\\equiv \\textrm{St}/\\alpha$, the ratio of the dimensionless stopping time to the turbulence parameter. The decoupling of the solid particles relative to the gas is significant when $S$ exceeds unity. $S$ is expected to increase with time and heliocentric distance. On the basis of (i) abundance of refractory inclusions (ii) proportion of matrix (iii) lithophile element abundances and (iv) oxygen isotopic composition of chon...

Jacquet, Emmanuel; Fromang, Sbastien

2012-01-01T23:59:59.000Z

482

Vibrated polar disks: spontaneous motion, binary collisions, and collective dynamics  

E-Print Network (OSTI)

We study the spontaneous motion, binary collisions, and collective dynamics of "polar disks", i.e. purpose-built particles which, when vibrated between two horizontal plates, move coherently along a direction strongly correlated to their intrinsic polarity. The motion of our particles, although nominally three-dimensional and complicated, is well accounted for by a two-dimensional persistent random walk. Their binary collisions are spatiotemporally extended events during which multiple actual collisions happen, yielding a weak average effective alignment. We show that this well-controlled, "dry active matter" system can display collective motion with orientationally-ordered regions of the order of the system size. We provide evidence of strong number density in the most ordered regimes observed. These results are discussed in the light of the limitations of our system, notably those due to the inevitable presence of walls.

Julien Deseigne; Sbastien Lonard; Olivier Dauchot; Hugues Chat

2012-01-29T23:59:59.000Z

483

Radial disk heating by more than one spiral density wave  

E-Print Network (OSTI)

We consider a differentially rotating, 2D stellar disk perturbed by two steady state spiral density waves moving at different patterns speeds. Our investigation is based on direct numerical integration of initially circular test-particle orbits. We examine a range of spiral strengths and spiral speeds and show that stars in this time dependent gravitational field can be heated (their random motions increased). This is particularly noticeable in the simultaneous propagation of a 2-armed spiral density wave near the corotation resonance (CR), and a weak 4-armed one near the inner and outer 4:1 Lindblad resonances. In simulations with 2 spiral waves moving at different pattern speeds we find: (1) the variance of the radial velocity, sigma_R^2, exceeds the sum of the variances measured from simulations with each individual pattern; (2) sigma_R^2 can grow with time throughout the entire simulation; (3) sigma_R^2 is increased over a wider range of radii compared to that seen with one spiral pattern; (4) particles diffuse radially in real space whereas they don't when only one spiral density wave is present. Near the CR with the stronger, 2-armed pattern, test particles are observed to migrate radially. These effects take place at or near resonances of both spirals so we interpret them as the result of stochastic motions. This provides a possible new mechanism for increasing the stellar velocity dispersion in galactic disks. If multiple spiral patterns are present in the Galaxy we predict that there should be large variations in the stellar velocity dispersion as a function of radius.

I. Minchev; A. C. Quillen

2005-10-28T23:59:59.000Z

484

Efficient Failure Recovery in Multi-Disk Multimedia Servers Harrick M. Vin, Prashant J. Shenoy and Sriram Rao  

E-Print Network (OSTI)

-invoked on-the-fly failure recovery process does not impose any additional load on the disk array. We also that each surviving disk would see an on-the-fly reconstruction load increase of G,1=D,1 instead of D,1=D,1Efficient Failure Recovery in Multi-Disk Multimedia Servers Harrick M. Vin, Prashant J. Shenoy

Vin, Harrick M.

485

ACCRETION OF GAS ONTO GAP-OPENING PLANETS AND CIRCUMPLANETARY FLOW STRUCTURE IN MAGNETIZED TURBULENT DISKS  

SciTech Connect

We have performed three-dimensional magnetohydrodynamical simulations of stellar accretion disks, using the PLUTO code, and studied the accretion of gas onto a Jupiter-mass planet and the structure of the circumplanetary gas flow after opening a gap in the disk. We compare our results with simulations of laminar, yet viscous disks with different levels of an {alpha}-type viscosity. In all cases, we find that the accretion flow across the surface of the Hill sphere of the planet is not spherically or azimuthally symmetric, and is predominantly restricted to the mid-plane region of the disk. Even in the turbulent case, we find no significant vertical flow of mass into the Hill sphere. The outer parts of the circumplanetary disk are shown to rotate significantly below Keplerian speed, independent of viscosity, while the circumplanetary disk density (therefore the angular momentum) increases with viscosity. For a simulation of a magnetized turbulent disk, where the global averaged alpha stress is {alpha}{sub MHD} = 10{sup -3}, we find the accretion rate onto the planet to be M-dot {approx}2 Multiplication-Sign 10{sup -6}M{sub J} yr{sup -1} for a gap surface density of 12 g cm{sup -2}. This is about a third of the accretion rate obtained in a laminar viscous simulation with equivalent {alpha} parameter.

Uribe, A. L. [University of Chicago, Chicago, IL 60637 (United States); Klahr, H.; Henning, Th., E-mail: uribe@oddjob.uchicago.edu [Max-Planck-Institut fuer Astronomie, Heidelberg (Germany)

2013-06-01T23:59:59.000Z

486

A SPITZER IRS SURVEY OF NGC 1333: INSIGHTS INTO DISK EVOLUTION FROM A VERY YOUNG CLUSTER  

SciTech Connect

We report on the {lambda} = 5-36 {mu}m Spitzer Infrared Spectrograph (IRS) spectra of 79 young stellar objects in the very young nearby cluster NGC 1333. NGC 1333's youth enables the study of early protoplanetary disk properties, such as the degree of settling and the formation of gaps and clearings. We construct spectral energy distributions (SEDs) using our IRS data as well as published photometry and classify our sample into SED classes. Using 'extinction-free' spectral indices, we determine whether the disk, envelope, or photosphere dominates the spectrum. We analyze the dereddened spectra of objects that show disk-dominated emission using spectral indices and properties of silicate features in order to study the vertical and radial structure of protoplanetary disks in NGC 1333. At least nine objects in our sample of NGC 1333 show signs of large (several AU) radial gaps or clearings in their inner disk. Disks with radial gaps in NGC 1333 show more nearly pristine silicate dust than their radially continuous counterparts. We compare properties of disks in NGC 1333 to those in three other well-studied regions, Taurus-Auriga, Ophiuchus, and Chamaeleon I, and find no difference in their degree of sedimentation and dust processing.

Arnold, L. A.; Watson, Dan M.; Kim, K. H.; Manoj, P.; Remming, I.; Sheehan, P.; Forrest, W. J.; Mamajek, E. [Department of Physics and Astronomy, University of Rochester, Rochester, NY 14627 (United States); Adame, L.; McClure, M. [Department of Astronomy, University of Michigan, 500 Church Street, Dennison Building, Ann Arbor, MI 48109 (United States); Furlan, E. [Jet Propulsion Laboratory, California Institute of Technology, Mail Stop 264-723, 4800 Oak Grove Drive, Pasadena, CA 91109 (United States); Espaillat, C. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, MS-78, Cambridge, MA 02138 (United States); Ausfeld, K.; Rapson, V. A., E-mail: laa@pas.rochester.edu, E-mail: dmw@pas.rochester.edu [Center for Imaging Science, Rochester Institute of Technology, 54 Lomb Memorial Drive, Rochester, NY 14623 (United States)

2012-08-01T23:59:59.000Z

487

Gross crack initiation and propagation in brittle thin solid and annular disks subjected to impact loading  

SciTech Connect

This paper derives from a study of grinding wheel break-up behavior due to impact. The impact fracture characteristics of circular disks of plaster of Paris with a concentric central hole were studied experimentally for three types of loading: (a) when the disks were suspended freely and loaded intensely at one point on their circumference by an explosive detonator; (b) when the disks were allowed to fall under gravity from a certain height on to a rigid base; and (c) when a disk, resting on a rigid base, was struck by a flat ended rigid body which was dropped on to it from a certain height. Quasi-static flattening tests on the disks were also carried out. The paper describes a theoretical investigation into the stress analysis of disks under impact, classifies the relevant damage sustained by them and attempts to unify the ''gross'' impact fracture patterns which arise in different modes of dynamic loading. The extent of local flattening of the quasi-statically loaded disks before fracture, is also reported. Good correlation between the theory and experimental results is obtained, especially for rings of diameter ratio (D /SUB i/ /D/sub 0/) of around 0.5.

Johnson, W.; Bai, Y.L.; Ghosh, S.K.

1984-04-01T23:59:59.000Z

488

Deep Spitzer spectroscopy of the `Flying Saucer' edge-on disk: Large grains beyond 50 AU  

E-Print Network (OSTI)

We present deep Spitzer-IRS low-resolution (lambda/Delta lambda ~ 100) 5-35 micron spectroscopy of the edge-on disk ``the Flying Saucer'' (2MASS J16281370-2431391) in the Ophiuchus molecular cloud. The spectral energy distribution exhibits the characteristic two-peak shape predicted for a circumstellar disk viewed very close to edge-on. The short-wavelength peak is entirely due to photons scattered off the surface of the disk, while the long-wavelength peak is due to thermal emission from the disk itself. The Spitzer spectrum represents the first spectroscopic detection of scattered light out to 15 micron from a bona-fide, isolated edge-on disk around a T Tauri star. The depth and the wavelength of the mid-infrared "valley" of the SED give direct constraints on the size distribution of large grains in the disk. Using a 2D continuum radiative transfer model, we find that a significant amount of 5-10 micron-sized grains is required in the surface layers of the disk at radii of 50-300 AU. The detection of relati...

Pontoppidan, K M; Blake, G A; Van Dishoeck, E F; Dullemond, C P; Pontoppidan, Klaus M.; Stapelfeldt, Karl R.; Blake, Geoffrey A.; Dishoeck, Ewine F. van; Dullemond, Cornelis P.

2007-01-01T23:59:59.000Z

489

ON THE SIZE EVOLUTION OF A GALACTIC DISK IN HIERARCHICAL MERGING OF COLD DARK MATTER HALOS  

SciTech Connect

We investigate the dynamical effects of dark matter subhalos on the structure and evolution of a galactic disk, using the semi-analytic method that includes approximated and empirical relations as achieved in detailed numerical simulations of the cold dark matter model. We calculate the upper limit for the size of a galactic disk at a specific redshift z, based on the orbital properties of subhalos characterized by their pericentric distances from the center of a host halo. We find that this possibly largest size of a disk as determined by the smallest pericentric distances of subhalos shows the characteristic properties, which are basically in agreement with an observed galactic disk at low and high z. Namely, it is found that a massive disk can have a larger size than a less massive one, because of its stability against the destruction effect of subhalos. Also, with fixed mass, the size of a galactic disk at low z can be larger than that at high z, reflecting the orbital evolution of subhalos with respect to a host halo. These results suggest that the presence and structure of a galactic disk may be dynamically limited by the interaction with dark matter substructures, especially at high z.

Hayashi, Hirohito; Chiba, Masashi [Astronomical Institute, Tohoku University, Aoba-ku, Sendai 980-8578 (Japan)

2009-09-10T23:59:59.000Z

490

On relation between rest frame and light-front descriptions of quarkonium  

E-Print Network (OSTI)

In this paper we study the relation between the light-front (infinite momentum) and rest-frame descriptions of quarkonia. While the former is more convenient for high-energy production, the latter is usually used for the evaluation of charmonium properties. In particular, we discuss the dynamics of a relativistically moving system with nonrelativistic internal motion and give relations between rest frame and light-front potentials used for the description of quarkonium states. We consider two approximations, first the small coupling regime, and next the nonperturbative small binding energy approximation. In both cases we get consistent results. Our results could be relevant for the description of final state interactions in a wide class of processes, including quarkonium production on nuclei and plasma. Moreover, they can be extended to the description of final state interactions in the production of weakly bound systems, such as for example the deuteron.

Kopeliovich, B Z; Schmidt, Ivan; Siddikov, M

2015-01-01T23:59:59.000Z

491

Wave fronts, pulses and wave trains in photoexcited superlattices behaving as excitable or oscillatory media  

E-Print Network (OSTI)

Undoped and strongly photoexcited semiconductor superlattices with field-dependent recombination behave as excitable or oscillatory media with spatially discrete nonlinear convection and diffusion. Infinitely long, dc-current-biased superlattices behaving as excitable media exhibit wave fronts with increasing or decreasing profiles, whose velocities can be calculated by means of asymptotic methods. These superlattices can also support pulses of the electric field. Pulses moving downstream with the flux of electrons can be constructed from their component wave fronts, whereas pulses advancing upstream do so slowly and experience saltatory motion: they change slowly in long intervals of time separated by fast transitions during which the pulses jump to the previous superlattice period. Photoexcited superlattices can also behave as oscillatory media and exhibit wave trains.

J. I. Arana; L. L. Bonilla; H. T. Grahn

2011-09-30T23:59:59.000Z

492

Engineering Spectral Control Using Front Surface Filters for Maximum TPV Energy Conversion System Performance  

SciTech Connect

Energy conversion efficiencies of better than 23% have been demonstrated for small scale tests of a few thermophotovoltaic (TPV) cells using front surface, tandem filters [1, 2]. The engineering challenge is to build this level of efficiency into arrays of cells that provide useful levels of energy. Variations in cell and filter performance will degrade TPV array performance. Repeated fabrication runs of several filters each provide an initial quantification of the fabrication variation for front surface, tandem filters for TPV spectral control. For three performance statistics, within-run variation was measured to be 0.7-1.4 percent, and run-to-run variation was measured to be 0.5-3.2 percent. Fabrication runs using a mask have been shown to reduce variation across interference filters from as high as 8-10 percent to less than 1.5 percent. Finally, several system design and assembly approaches are described to further reduce variation.

T Rahmlow, Jr; J Lazo-Wasem, E Gratrix; J Azarkevich; E Brown; D DePoy; D Eno; P Fourspring; J Parrington; R Mahorter; B Wernsman

2004-10-14T23:59:59.000Z

493

Engineering Spectral Control Using Front Surface Filters for Maximum TPV Energy Conversion System Performance  

SciTech Connect

Energy conversion efficiencies of better than 23% have been demonstrated for small scale tests of a few thermophotovoltaic (TPV) cells using front surface, tandem filters [1,2]. The engineering challenge is to build this level of efficiency into arrays of cells that provide useful levels of energy. Variations in cell and filter performance will degrade TPV array performance. Repeated fabrication runs of several filters each provide an initial quantification of the fabrication variation for front surface, tandem filters for TPV spectral control. For three performance statistics, within-run variation was measured to be 0.7-1.4 percent, and run-to-run variation was measured to be 0.5-3.2 percent. Fabrication runs using a mask have been shown to reduce variation across interference filters from as high 8-10 percent to less than 1.5 percent. Finally, several system design and assembly approaches are described to further reduce variation.

TD Rahmlaw, Jr; JE Lazo-Wasem; EJ Gratrix; JJ Azarkevich; EJ Brown; DM DePoy; DR Eno; PM Fourspring; JR Parrington; RG Mahorter; B Wernsman

2004-08-04T23:59:59.000Z

494

On relation between rest frame and light-front descriptions of quarkonium  

E-Print Network (OSTI)

In this paper we study the relation between the light-front (infinite momentum) and rest-frame descriptions of quarkonia. While the former is more convenient for high-energy production, the latter is usually used for the evaluation of charmonium properties. In particular, we discuss the dynamics of a relativistically moving system with nonrelativistic internal motion and give relations between rest frame and light-front potentials used for the description of quarkonium states. We consider two approximations, first the small coupling regime, and next the nonperturbative small binding energy approximation. In both cases we get consistent results. Our results could be relevant for the description of final state interactions in a wide class of processes, including quarkonium production on nuclei and plasma. Moreover, they can be extended to the description of final state interactions in the production of weakly bound systems, such as for example the deuteron.

B. Z. Kopeliovich; E. Levin; Ivan Schmidt; M. Siddikov

2015-01-07T23:59:59.000Z

495

VISCOUS ACCRETION OF A POLYTROPIC SELF-GRAVITATING DISK IN THE PRESENCE OF WIND  

SciTech Connect

Self-similar and semi-analytical solutions are found for the height-averaged equations governing the dynamical behavior of a polytropic, self-gravitating disk under the effects of winds around the nascent object. In order to describe the time evolution of the system, we adopt a radius-dependent mass loss rate, then highlight its importance on both the traditional {alpha} and innovative {beta} models of viscosity prescription. In agreement with some other studies, our solutions represent that the Toomre parameter is less than one in most regions on the {beta}-disk, which indicates that in such disks gravitational instabilities can occur at various distances from the central accretor. So, the {beta}-disk model might provide a good explanation of how the planetary systems form. The purpose of the present work is twofold: examining the structure of a disk with wind in comparison to a no-wind solution and seeing whether the adopted viscosity prescription significantly affects the dynamical behavior of the disk-wind system. We also considered the temperature distribution in our disk by a polytropic condition. The solutions imply that, under our boundary conditions, the radial velocity is larger for {alpha}-disks and increases as wind becomes stronger in both viscosity models. Also, we noticed that the disk thickness increases by amplifying the wind or adopting larger values for the polytropic exponent {gamma}. It also may globally decrease if one prescribes a {beta}-model for the viscosity. Moreover, in both viscosity models, the surface density and mass accretion rate diminish as the wind gets stronger or {gamma} increases.

Abbassi, Shahram; Nourbakhsh, Erfan [School of Physics, Damghan University, P.O. Box 36715-364, Damghan (Iran, Islamic Republic of); Shadmehri, Mohsen, E-mail: abbassi@ipm.ir, E-mail: e.nourbakhsh@mail.sbu.ac.ir, E-mail: m.shadmehri@gu.ac.ir [Department of Physics, Golestan University, Basij Square, Gorgan (Iran, Islamic Republic of)

2013-03-10T23:59:59.000Z

496

Modeling the Resolved Disk around the Class0 Protostar L1527  

Science Journals Connector (OSTI)

We present high-resolution sub/millimeter interferometric imaging of the Class0 protostar L1527 IRS (IRAS04368+2557) at ? = 870 ?m and 3.4mm from the Submillimeter Array and