National Library of Energy BETA

Sample records for front disc brakes

  1. Brake System Modeling, Control And Integrated Brake/throttle Switching Phase I

    E-Print Network [OSTI]

    Hedrick, Karl; Et. al.,

    1997-01-01

    and vacuum chambers, the intake manifold, the secondary brake line at the master cylinder and the front brake on the same hydraulic

  2. A diagnostic system for air brakes in commercial vehicles 

    E-Print Network [OSTI]

    Coimbatore Subramanian, Shankar Ram

    2007-09-17

    ............. 14 4 The S-cam foundation brake ....................... 15 5 A schematic of the drum brake ..................... 16 6 A schematic of the experimental setup ................. 24 7 A sectional view of the treadle valve .................. 26 8 A layout... the disc brake and the drum brake. In this dissertation, the main focus will be restricted to air brake systems that use S-cam drum foundation brakes. A. Background and motivation The safety of vehicles operating on the road depends amongst other things...

  3. Gravity brake

    DOE Patents [OSTI]

    Lujan, Richard E. (Santa Fe, NM)

    2001-01-01

    A mechanical gravity brake that prevents hoisted loads within a shaft from free-falling when a loss of hoisting force occurs. A loss of hoist lifting force may occur in a number of situations, for example if a hoist cable were to break, the brakes were to fail on a winch, or the hoist mechanism itself were to fail. Under normal hoisting conditions, the gravity brake of the invention is subject to an upward lifting force from the hoist and a downward pulling force from a suspended load. If the lifting force should suddenly cease, the loss of differential forces on the gravity brake in free-fall is translated to extend a set of brakes against the walls of the shaft to stop the free fall descent of the gravity brake and attached load.

  4. Braking system

    DOE Patents [OSTI]

    Norgren, D.U.

    1982-09-23

    A balanced braking system comprising a plurality of braking assemblies located about a member to be braked. Each of the braking assemblies consists of a spring biased piston of a first material fitted into a body of a different material which has a greater contraction upon cooling than the piston material. The piston is provided with a recessed head portion over which is positioned a diaphragm and forming a space therebetween to which is connected a pressurized fluid supply. The diaphragm is controlled by the fluid in the space to contact or withdraw from the member to be braked. A cooling means causes the body within which the piston is fitted to contract more than the piston, producing a tight shrink fit therebetween. The braking system is particularly applicable for selectively braking an arbor of an electron microscope which immobilizes, for example, a vertically adjustable low temperature specimen holder during observation. The system provides balanced braking forces which can be easily removed and re-established with minimal disturbance to arbor location.

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

    E-Print Network [OSTI]

    Ramaratham, Srivatsan

    2008-10-10

    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 to maintenance. Brake defects such as leaks are a major... and schematic of operation. . . . . . . . . . . . . 7 3 A typical drum brake assembly. . . . . . . . . . . . . . . . . . . . . . 8 4 Front and rear brake chambers. . . . . . . . . . . . . . . . . . . . . . 8 5 Automatic slack adjuster construction...

  6. Hybrid: Braking

    Alternative Fuels and Advanced Vehicles Data Center [Office of Energy Efficiency and Renewable Energy (EERE)]

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page on Google Bookmark EERE: Alternative Fuels Data Center Home Page on Delicious Rank EERE: Alternative Fuels Data Center HomeVehicle Replacement VouchersBraking

  7. Full Hybrid: Braking

    Alternative Fuels and Advanced Vehicles Data Center [Office of Energy Efficiency and Renewable Energy (EERE)]

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page on Google Bookmark EERE: Alternative Fuels Data Center Home Page on Delicious Rank EERE: Alternative Fuels Data Center HomeVehicle Replacement VouchersBraking button highlighted Stopped

  8. Combined hydraulic and regenerative braking system

    DOE Patents [OSTI]

    Venkataperumal, Rama R. (Troy, MI); Mericle, Gerald E. (Mount Clemens, MI)

    1981-06-02

    A combined hydraulic and regenerative braking system and method for an electric vehicle, with the braking system being responsive to the applied hydraulic pressure in a brake line to control the braking of the vehicle to be completely hydraulic up to a first level of brake line pressure, to be partially hydraulic at a constant braking force and partially regenerative at a linearly increasing braking force from the first level of applied brake line pressure to a higher second level of brake line pressure, to be partially hydraulic at a linearly increasing braking force and partially regenerative at a linearly decreasing braking force from the second level of applied line pressure to a third and higher level of applied line pressure, and to be completely hydraulic at a linearly increasing braking force from the third level to all higher applied levels of line pressure.

  9. Regenerative braking device

    DOE Patents [OSTI]

    Hoppie, Lyle O. (Birmingham, MI)

    1982-01-12

    Disclosed are several embodiments of a regenerative braking device for an automotive vehicle. The device includes a plurality of rubber rollers (24, 26) mounted for rotation between an input shaft (14) connectable to the vehicle drivetrain and an output shaft (16) which is drivingly connected to the input shaft by a variable ratio transmission (20). When the transmission ratio is such that the input shaft rotates faster than the output shaft, the rubber rollers are torsionally stressed to accumulate energy, thereby slowing the vehicle. When the transmission ratio is such that the output shaft rotates faster than the input shaft, the rubber rollers are torsionally relaxed to deliver accumulated energy, thereby accelerating or driving the vehicle.

  10. Variable ratio regenerative braking device

    DOE Patents [OSTI]

    Hoppie, Lyle O. (Birmingham, MI)

    1981-12-15

    Disclosed is a regenerative braking device (10) for an automotive vehicle. The device includes an energy storage assembly (12) having a plurality of rubber rollers (26, 28) mounted for rotation between an input shaft (36) and an output shaft (42), clutches (38, 46) and brakes (40, 48) associated with each shaft, and a continuously variable transmission (22) connectable to a vehicle drivetrain and to the input and output shafts by the respective clutches. The rubber rollers are torsionally stressed to accumulate energy from the vehicle when the input shaft is clutched to the transmission while the brake on the output shaft is applied, and are torsionally relaxed to deliver energy to the vehicle when the output shaft is clutched to the transmission while the brake on the input shaft is applied. The transmission ratio is varied to control the rate of energy accumulation and delivery for a given rotational speed of the vehicle drivetrain.

  11. Turbulent drag reduction through oscillating discs

    E-Print Network [OSTI]

    Wise, Daniel J

    2014-01-01

    The changes of a turbulent channel flow subjected to oscillations of wall flush-mounted rigid discs are studied by means of direct numerical simulations. The Reynolds number is $R_\\tau$=$180$, based on the friction velocity of the stationary-wall case and the half channel height. The primary effect of the wall forcing is the sustained reduction of wall-shear stress, which reaches a maximum of 20%. A parametric study on the disc diameter, maximum tip velocity, and oscillation period is presented, with the aim to identify the optimal parameters which guarantee maximum drag reduction and maximum net energy saving, computed by taking into account the power spent to actuate the discs. This may be positive and reaches 6%. The Rosenblat viscous pump flow is used to predict the power spent for disc motion in the turbulent channel flow and to estimate localized and transient regions over the disc surface subjected to the turbulent regenerative braking effect, for which the wall turbulence exerts work on the discs. The...

  12. Brake Defect Causation and Abatement Study (BDCAS)

    E-Print Network [OSTI]

    cost with proper re- pairs being made the first time and reduction in out-of-service vehicles #12; corrective actions and validate true abatement of initial out-of- service causation the FMCSA began the BDCAS brake efficiency data as new brakes are burnished; and where possible, collect brake efficiency data

  13. Commercial Motor Vehicle Brake Assessment Tools

    E-Print Network [OSTI]

    Commercial Motor Vehicle Brake Assessment Tools Commercial Motor Vehicle Roadside Technology to deceleration in g's ­ Passing score: BE43.5 · Enforcement tool for only 3 years. · Based solely on brake Brake Research · CMVRTC research built on these enforcement tools ­ Correlation Study ­ Level-1 / PBBT

  14. Brake blending strategy for a hybrid vehicle

    DOE Patents [OSTI]

    Boberg, Evan S. (Hazel Park, MI)

    2000-12-05

    A hybrid electric powertrain system is provided including a transmission for driving a pair of wheels of a vehicle and a heat engine and an electric motor/generator coupled to the transmission. A friction brake system is provided for applying a braking torque to said vehicle. A controller unit generates control signals to the electric motor/generator and the friction brake system for controllably braking the vehicle in response to a drivers brake command. The controller unit determines and amount of regenerative torque available and compares this value to a determined amount of brake torque requested for determining the control signals to the electric motor/generator and the friction brake system.

  15. Commercial Motor Vehicle Brake-Related Research

    E-Print Network [OSTI]

    Commercial Motor Vehicle Brake-Related Research Commercial Motor Vehicle Roadside Technology Corridor Safety Technology Showcase October 14, 2010 Commercial Motor Vehicle Roadside Technology Corridor

  16. Multidisciplinary design optimization of an automotive magnetorheological brake design

    E-Print Network [OSTI]

    Park, Edward

    Multidisciplinary design optimization of an automotive magnetorheological brake design Edward J to the elec- tromagnet. Key issues involved in the initial design of the automotive MR brake are presented: Magnetorheological fluid; Automotive brake; Finite element analysis; Computational fluid dynamics; Multidisciplinary

  17. Svendborg Brakes | Open Energy Information

    Open Energy Info (EERE)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page on Google Bookmark EERE: Alternative Fuels Data Center Home Page on QA:QA J-E-1 SECTION J APPENDIX E LIST OFAMERICA'SHeavyAgencyTendo New Energy EquipmentSvendborg Brakes Jump to:

  18. 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

  19. Turbine disc sealing assembly

    DOE Patents [OSTI]

    Diakunchak, Ihor S.

    2013-03-05

    A disc seal assembly for use in a turbine engine. The disc seal assembly includes a plurality of outwardly extending sealing flange members that define a plurality of fluid pockets. The sealing flange members define a labyrinth flow path therebetween to limit leakage between a hot gas path and a disc cavity in the turbine engine.

  20. An engine air-brake integration study

    E-Print Network [OSTI]

    Mulchandani, Hiten

    2011-01-01

    The feasibility of operating an engine air-brake (EAB) integrated with a pylon duct bifurcation in a realistic aircraft engine environment has been analyzed. The EAB uses variable exit guide vanes downstream of a high ...

  1. Method and apparatus for wind turbine braking

    DOE Patents [OSTI]

    Barbu, Corneliu (Laguna Hills, CA); Teichmann, Ralph (Nishkayuna, NY); Avagliano, Aaron (Houston, TX); Kammer, Leonardo Cesar (Niskayuna, NY); Pierce, Kirk Gee (Simpsonville, SC); Pesetsky, David Samuel (Greenville, SC); Gauchel, Peter (Muenster, DE)

    2009-02-10

    A method for braking a wind turbine including at least one rotor blade coupled to a rotor. The method includes selectively controlling an angle of pitch of the at least one rotor blade with respect to a wind direction based on a design parameter of a component of the wind turbine to facilitate reducing a force induced into the wind turbine component as a result of braking.

  2. Contactless magnetic brake for automotive applications 

    E-Print Network [OSTI]

    Gay, Sebastien Emmanuel

    2009-05-15

    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...

  3. CMV Brake Wear and Performance Test Little is known about the brake

    E-Print Network [OSTI]

    inspections were due to brake defects. Additionally, brake maintenance and repair present a significant cost as part of an 18-month Field Operational Test. Parameters Being Measured The PBBT machine uses in Data, Statistical Analysis Geo-Spatial Information Tools Defense Transportation Energy Policy Analysis

  4. Adaptive controller for regenerative and friction braking system

    DOE Patents [OSTI]

    Davis, Roy I. (Ypsilanti, MI)

    1990-01-01

    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.

  5. Adaptive controller for regenerative and friction braking system

    DOE Patents [OSTI]

    Davis, R.I.

    1990-10-16

    A regenerative and friction braking system for a vehicle having one or more road wheels 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 road wheels 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 road wheels of the vehicle without skidding or slipping will not be exceeded. 8 figs.

  6. Electric vehicle regenerative antiskid braking and traction control system

    DOE Patents [OSTI]

    Cikanek, S.R.

    1995-09-12

    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 hydraulic 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. 10 figs.

  7. Electric vehicle regenerative antiskid braking and traction control system

    DOE Patents [OSTI]

    Cikanek, Susan R. (Wixom, MI)

    1995-01-01

    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.

  8. Design Restrictions Ground clearance Brake components cannot contact

    E-Print Network [OSTI]

    Provancher, William

    of Mechanical Engineering, University of Utah Test Results Heat Test ­ apply pressure to the rotating brake. The truck and brake must be strong but not heavy. · Temperature ­ The brake will generate a lot of heat. The epoxy, wheels and bearings must all be able to withstand high heat. · Testing of Realistic Conditions

  9. Engine brake control in automatic transmission

    SciTech Connect (OSTI)

    Hayasaki, K.; Sugano, K.

    1988-09-13

    This patent describes an engine braking control for a transmission for an automotive vehicle having an engine, the transmission including an input member drivingly coupled to the engine and an output member subject to load from driving wheels of the automotive vehicle, the transmission also including a first rotary member, a second rotary member, a hydraulically operated clutch selectively establishing a drive connection between the first rotary member and the second rotary member, and a one-way clutch arranged in parallel to the hydraulically operated clutch such that when the hydraulically operated clutch is released, the one-way clutch transmits forward torque from the first rotary member to the second rotary member, but interrupts transmission of revers torque to the first rotary member from the second rotary member, the engine braking control comprising: means for providing an engine braking command fluid pressure signal when demanded by a vehicle operator; a valve means for normally discharging hydraulic fluid from the hydraulically operated clutch to deactivate the hydraulically operated clutch, the valve means being fluidly connected to the hydraulically operated clutch, the engine braking command fluid pressure signal providing means and a drain port. The valve means including a valve spool having a first position where the hydraulically operated clutch is allowed to communicate with the drain port to permit discharge of hydraulic fluid therefrom and thus the hydraulically operated clutch is caused to be deactivated and a second position where the hydraulically operated clutch is disconnected from the drain port and allowed to communicate with the engine braking command fluid pressure signal.

  10. Hybrid Braking System for Non-Drive Axles | Department of Energy

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

    Braking System for Non-Drive Axles Hybrid Braking System for Non-Drive Axles A hybrid braking system is designed to conserve diesel fuel (or alternative fuels) by using...

  11. Braking system for use with an arbor of a microscope

    DOE Patents [OSTI]

    Norgren, Duane U. (Orinda, CA)

    1984-01-01

    A balanced braking system comprising a plurality of braking assemblies located about a member to be braked. Each of the braking assemblies consists of a spring biased piston of a first material fitted into a body of a different material which has a greater contraction upon cooling than the piston material. The piston is provided with a recessed head portion over which is positioned a diaphragm and forming a space therebetween to which is connected a pressurized fluid supply. The diaphragm is controlled by the fluid in the space to contact or withdraw from the member to be braked. A cooling device causes the body within which the piston is fitted to contract more than the piston, producing a tight shrink fit therebetween. The braking system is particularly applicable for selectively braking an arbor of an electron microscope which immobilizes, for example, a vertically adjustable low temperature specimen holder during observation. The system provides balanced braking forces which can be easily removed and re-established with minimal disturbance to arbor location.

  12. Development of Diagnostic Algorithms for Air Brakes in Trucks 

    E-Print Network [OSTI]

    Dhar, Sandeep

    2011-10-21

    In this dissertation, we focus on development of algorithms for estimating the severity of air leakage and for predicting the out-of-adjustment of pushrod in an air brake system of heavy commercial vehicles. The leakage of air from the brake system...

  13. A pressure control scheme for air brakes in commercial vehicles 

    E-Print Network [OSTI]

    Bowlin, Christopher Leland

    2007-04-25

    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...

  14. Enclosed rotary disc air pulser

    DOE Patents [OSTI]

    Olson, A. L. (Idaho Falls, ID); Batcheller, Tom A. (Idaho Falls, ID); Rindfleisch, J. A. (Arco, ID); Morgan, John M. (Arco, ID)

    1989-01-01

    An enclosed rotary disc air pulser for use with a solvent extraction pulse olumn includes a housing having inlet, exhaust and pulse leg ports, a shaft mounted in the housing and adapted for axial rotation therein, first and second disc members secured to the shaft within the housing in spaced relation to each other to define a chamber therebetween, the chamber being in communication with the pulse leg port, the first disc member located adjacent the inlet port, the second disc member being located adjacent the exhaust port, each disc member having a milled out portion, the disc members positioned on the shaft so that as the shaft rotates, the milled out portions permit alternative cyclical communication between the inlet port and the chamber and the exhaust port and the chamber.

  15. Front Burner- Issue 14

    Broader source: Energy.gov [DOE]

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

  16. Front Burner- Issue 15

    Broader source: Energy.gov [DOE]

    The Cybersecurity Front Burner Issue No. 15 addresses the DOE eSCRM Program and Secure Online Shopping.

  17. Airbus A320 Braking as Predicate-Action Peter B. Ladkin

    E-Print Network [OSTI]

    Ladkin, Peter B.

    to interest us and others in the design of the A320 braking system [FI.93a, FI.93b, FI.93c]. This paper]. The Braking System Design of the A320. The braking system design of the A320 is described in the A320 Flight). The brakes and anti-skid system are described in [FCOM, 1.32.30: Landing Gear: Brakes and Anti

  18. Regenerative braking on bicycles to power LED safety flashers

    E-Print Network [OSTI]

    Collier, Ian M

    2005-01-01

    This work develops a method for capturing some of the kinetic energy ordinarily lost during braking on bicycles to power LED safety flashers. The system is designed to eliminate: (a) battery changing in popular LED flashers, ...

  19. Front Burner- Issue 18

    Broader source: Energy.gov [DOE]

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

  20. Front Burner- Issue 13

    Broader source: Energy.gov [DOE]

    The Cybersecurity Front Burner Issue No. 13 contained a message from the Associate Chief Information Officer (ACIO) for Cybersecurity as well as a listing of recommended cybersecurity practices.

  1. Disc Manufacturing, Inc. A QUIXOTE COMPANY

    E-Print Network [OSTI]

    Gupta, Varun

    Disc Manufacturing, Inc. A QUIXOTE COMPANY Introduction to ISO 9660, what it is, how it is implemented, and how it has been extended. Clayton Summers Copyright © 1993 by Disc Manufacturing, Inc. All rights reserved. #12;WHO IS DMI? Disc Manufacturing, Inc. (DMI) manufactures all compact disc formats (i

  2. Magnetorotational instability in protoplanetary discs

    E-Print Network [OSTI]

    Raquel Salmeron; Mark Wardle

    2004-08-24

    We investigate the linear growth and vertical structure of the magnetorotational instability (MRI) in weakly ionised, stratified accretion discs. The magnetic field is initially vertical and dust grains are assumed to have settled towards the midplane, so charges are carried by electrons and ions only. Solutions are obtained at representative radial locations from the central protostar for different choices of the initial magnetic field strength, sources of ionisation, and disc surface density. The MRI is active over a wide range of magnetic field strengths and fluid conditions in low conductivity discs. For the minimum-mass solar nebula model, incorporating cosmic ray ionisation, perturbations grow at 1 AU for B < 8 G. For a significant subset of these strengths (0.2 - 5 G), the growth rate is of order the ideal MHD rate (0.75 Omega). Similarly, when cosmic rays are assumed to be excluded from the disc by the winds emitted by the magnetically active protostar, unstable modes grow at this radius for B less than about 2 G. This study shows that, despite the low magnetic coupling, the magnetic field is dynamically important for a large range of fluid conditions and field strengths in protostellar discs. Hall diffusion largely determines the structure and growth rate of these perturbations for all studied radii. At radii of order 1 AU, in particular, it is crucial to incorporate the full conductivity tensor in studies of the dynamics of astrophysical discs. (Abridged)

  3. Kinematic Detection of the Galactic Nuclear Disc

    E-Print Network [OSTI]

    Schönrich, Ralph; Sale, Stuart E

    2015-01-01

    We report the detection of the Galactic nuclear disc in line-of-sight kinematics of stars, measured with infrared spectroscopy from APOGEE. The nuclear disc is found to have a rotation velocity V ~ 120km/s comparable to the gas disc. The current data suggest that this disc is kinematically quite cold and has a small vertical extent of order 50pc. The stellar kinematics suggest a truncation radius of the stellar disc at a galactocentric radius R ~ 150pc, and provide tentative evidence for an overdensity at the position of the ring found in the molecular gas disc.

  4. Design considerations for an automotive magnetorheological brake Kerem Karakoc, Edward J. Park *, Afzal Suleman

    E-Print Network [OSTI]

    Park, Edward

    Design considerations for an automotive magnetorheological brake Kerem Karakoc, Edward J. Park *, Afzal Suleman Department of Mechanical Engineering, University of Victoria, P.O. Box 3055, STN CSC February 2008 Available online xxxx Keywords: Mechatronic design Magnetorheological fluid Automotive brake

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

    E-Print Network [OSTI]

    Vilayannur Natarajan, Shankar

    2005-08-29

    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...

  6. Fuzzy logic electric vehicle regenerative antiskid braking and traction control system

    DOE Patents [OSTI]

    Cikanek, S.R.

    1994-10-25

    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. 123 figs.

  7. Fuzzy logic electric vehicle regenerative antiskid braking and traction control system

    DOE Patents [OSTI]

    Cikanek, Susan R. (Wixom, MI)

    1994-01-01

    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.

  8. Braking the Gas in the beta Pictoris Disk

    E-Print Network [OSTI]

    Fern'andez, R; Wu, Y; Brandeker, Alexis; Fern\\'andez, Rodrigo

    2006-01-01

    (Abridged) The main sequence star beta Pictoris hosts the best studied circumstellar disk to date. Nonetheless, a long-standing puzzle has been around since the detection of metallic gas in the disk: radiation pressure from the star should blow the gas away, yet the observed motion is consistent with Keplerian rotation. In this work we search for braking mechanisms that can resolve this discrepancy. We find that all species affected by radiation force are heavily ionized and dynamically coupled into a single fluid by Coulomb collisions, reducing the radiation force on species feeling the strongest acceleration. For a gas of solar composition, the resulting total radiation force still exceeds gravity, while a gas of enhanced carbon abundance could be self-braking. We also explore two other braking agents: collisions with dust grains and neutral gas. Grains surrounding beta Pic are photoelectrically charged to a positive electrostatic potential. If a significant fraction of the grains are carbonaceous (10% in t...

  9. Regenerative braking device with rotationally mounted energy storage means

    DOE Patents [OSTI]

    Hoppie, Lyle O. (Birmingham, MI)

    1982-03-16

    A regenerative braking device for an automotive vehicle includes an energy storage assembly (12) having a plurality of rubber rollers (26, 28) mounted for rotation between an input shaft (30) and an output shaft (32), clutches (50, 56) and brakes (52, 58) associated with each shaft, and a continuously variable transmission (22) connectable to a vehicle drivetrain and to the input and output shafts by the respective clutches. In a second embodiment the clutches and brakes are dispensed with and the variable ratio transmission is connected directly across the input and output shafts. In both embodiments the rubber rollers are torsionally stressed to accumulate energy from the vehicle when the input shaft rotates faster or relative to the output shaft and are torsionally relaxed to deliver energy to the vehicle when the output shaft rotates faster or relative to the input shaft.

  10. Aalborg Universitet Disturbance Control of the Hydraulic Brake in a Wind Turbine

    E-Print Network [OSTI]

    Yang, Zhenyu

    Aalborg Universitet Disturbance Control of the Hydraulic Brake in a Wind Turbine Jepsen, Frank Brake in a Wind Turbine. In Energy Conference and Exhibition (EnergyCon), 2010 IEEE International . (pp from vbn.aau.dk on: juli 07, 2015 #12;Disturbance Control of the Hydraulic Brake in a Wind Turbine

  11. The Chinese brake fern (Pteris vittata L.), native to China, is widely naturalized in

    E-Print Network [OSTI]

    Ma, Lena

    The Chinese brake fern (Pteris vittata L.), native to China, is widely naturalized in many areas and anatomical aspects of Chinese brake fern (Pteris vittata; Pteridaceae) Bhaskar Bondada1, Cong Tu, and Lena Ma-0290, U.S.A.; e-mail: lqma@ifas.ufl.edu). Sur- face structure and anatomical aspects of Chinese brake fern

  12. Regenerative Braking for an Electric Vehicle Using Ultracapacitors and a Buck-Boost Converter

    E-Print Network [OSTI]

    Catholic University of Chile (Universidad Católica de Chile)

    Regenerative Braking for an Electric Vehicle Using Ultracapacitors and a Buck-Boost Converter Juan situation (regenerative braking), the battery voltage goes up, and then the control needs to activate regenerative braking can be avoided #12;with the help of ultracapacitors. Besides, ultracapacitors allow

  13. Emission Factor for Antimony in Brake Abrasion Dusts as One of the

    E-Print Network [OSTI]

    Short, Daniel

    112-8551, Japan, and Akebono Brake Industry, Co., Ltd., 5-4-71 Higashi, Hanyu, Saitama 348-8509, Japan, and shape distributions, automotive brake abrasion dusts were suspected as one of the important sources factor that originates from automotive braking in order to quantitatively evaluate the contribution

  14. Tyre curve estimation in slip-controlled braking

    E-Print Network [OSTI]

    Miller, Jonathan I.; Cebon, David

    2015-06-09

    identifying a Kalman filter observer for vehicle handling dynamics. IMECHE Part D – J. of Auto. Eng. 2006; 220: 1063–1072. 27. Yi J et al. Emergency braking control with an observer-based dynamic tire/road friction model and wheel angular velocity... also used by Shim et al.15, and Hong et al.16 Unsal and Kachroo17 compared an EKF with a sliding mode observer to estimate vehicle velocity, using this estimated velocity with a nominal slip-friction curve to determine the braking force. The authors...

  15. Magnetorotational instability in protoplanetary discs

    E-Print Network [OSTI]

    Salmeron, Roberto Aureliano; Salmeron, Raquel; Wardle, Mark

    2004-01-01

    We investigate the linear growth and vertical structure of the magnetorotational instability (MRI) in weakly ionised, stratified accretion discs. The magnetic field is initially vertical and dust grains are assumed to have settled towards the midplane, so charges are carried by electrons and ions only. Solutions are obtained at representative radial locations from the central protostar for different choices of the initial magnetic field strength, sources of ionisation, and disc surface density. The MRI is active over a wide range of magnetic field strengths and fluid conditions in low conductivity discs. For the minimum-mass solar nebula model, incorporating cosmic ray ionisation, perturbations grow at 1 AU for B < 8 G. For a significant subset of these strengths (0.2 - 5 G), the growth rate is of order the ideal MHD rate (0.75 Omega). Similarly, when cosmic rays are assumed to be excluded from the disc by the winds emitted by the magnetically active protostar, unstable modes grow at this radius for B less...

  16. Braking index of isolated pulsars: open questions and ways forward

    E-Print Network [OSTI]

    Hamil, Oliver

    2015-01-01

    Isolated pulsars are rotating neutron stars with accurately measured angular velocities $\\Omega$, and their time derivatives which show unambiguously that the pulsars are slowing down. Although the exact mechanism of the spin-down is a question of debate, the commonly accepted view is that it arises either through emission of magnetic dipole radiation (MDR) from a rotating magnetized body, through emission of a relativistic particle wind, or via higher order magnetic multipole or gravitational quadrupole radiation. The calculated energy loss by a rotating pulsar is model dependent and leads to the power law $\\dot{\\Omega}$ = -K $\\Omega^{\\rm n}$ where $n$ is called the braking index. The theoretical value for braking index is $n = 1, 3, 5$ for wind, MDR, quadrupole radiation respectively. The accepted view is that pulsar braking is strongly dominated by MDR. Highly precise observations of isolated pulsars yield braking index values in the range $1 < n < 2.8$ which are consistently less than the value pred...

  17. Active Pedestrian Safety by Automatic Braking and Evasive Steering

    E-Print Network [OSTI]

    Gavrila, Dariu M.

    1 Active Pedestrian Safety by Automatic Braking and Evasive Steering C. Keller, T. Dang, H. Fritz of crashes. This paper presents a novel active pedestrian safety system, which combines sensing, situation two complementary approaches for added robustness: motion-based object detection and pedestrian

  18. Heavy and Overweight Vehicle Brake Testing: Five-Axle Combination Tractor-Flatbed Final Report

    SciTech Connect (OSTI)

    Lascurain, Mary Beth; Capps, Gary J; Franzese, Oscar

    2013-10-01

    The Federal Motor Carrier Safety Administration, in coordination with the Federal Highway Administration, sponsored the Heavy and Overweight Vehicle Brake Testing (HOVBT) program in order to provide information about the effect of gross vehicle weight (GVW) on braking performance. Because the Federal Motor Carrier Safety Regulations limit the number of braking system defects that may exist for a vehicle to be allowed to operate on the roadways, the examination of the effect of brake defects on brake performance for increased loads is also relevant. The HOVBT program seeks to provide relevant information to policy makers responsible for establishing load limits, beginning with providing test data for a combination tractor/trailer. This testing was conducted on a five-axle combination vehicle with tractor brakes meeting the Reduced Stopping Distance requirement rulemaking. This report provides a summary of the testing activities, the results of various analyses of the data, and recommendations for future research. Following a complete brake rebuild, instrumentation, and brake burnish, stopping tests were performed from 20 and 40 mph with various brake application pressures (15 psi, 25 psi, 35 psi, 45 psi, 55 psi, and full system pressure). These tests were conducted for various brake conditions at the following GVWs: 60,000, 80,000, 91,000, 97,000, 106,000, and 116,000 lb. The 80,000-lb GVWs included both balanced and unbalanced loads. The condition of the braking system was also varied. To introduce these defects, brakes (none, forward drive axle, or rear trailer axle) were made inoperative. In addition to the stopping tests, performance-based brake tests were conducted for the various loading and brake conditions. Analysis of the stopping test data showed the stopping distance to increase with load (as expected) and also showed that more braking force was generated by the drive axle brakes than the trailer axle brakes. The constant-pressure stopping test data revealed a linear relationship between brake application pressure and was used to develop an algorithm to normalize stopping data for weight and initial speed.

  19. RESEARCH FRONT CSIRO PUBLISHING Foreword

    E-Print Network [OSTI]

    Short, Daniel

    it is now being used extensively in industry[3] and for items such as car brake linings[4] and in fire to organisms is not well understood. Antimony is a global contaminant and there is an urgent need to improve of analytical procedures for measuring trace contaminants in water, sediment and biota. He is also director

  20. Energy Efficiency in Heavy Vehicle Tires, Drivetrains, and Braking Systems

    SciTech Connect (OSTI)

    Peter J. Blau

    2000-04-26

    This document was prepared to support the primary goals of the Department of Energy, Office of Heavy Vehicle Technologies. These were recently stated as follows: ''Develop by 2004 the enabling technologies for a class 7-8 truck with a fuel efficiency of 10 mpg (at 65 mph) which will meet prevailing emission standards. For Class 3-6 trucks operating on an urban driving cycle, develop by 2004 commercially viable vehicles that achieve at least double the fuel economy of comparable current vehicles (1999), and as a research goal, reduce criteria pollutants to 30% below EPA standards. Develop by 2004 the diesel engine enabling technologies to support large-scale industry dieselization of Class 1 and 2 trucks, achieving a 35 % fuel efficiency improvement over comparable gasoline-fueled trucks, while meeting applicable emissions standards.'' The enabling technologies for improving the fuel efficiency of trucks, include not only engine technologies but also technologies involved with lowering the rolling resistance of tires, reducing vehicle aerodynamic drag, improving thermal management, and reducing parasitic frictional losses in drive train components. Opportunities also exist for making better use of the energy that might ordinarily be dissipated during vehicle braking. Braking systems must be included in this evaluation since safety in truck operations is vital, and braking requirements are greater for vehicles having lowered resistance to rolling. The Office of Heavy Vehicle Technologies has initiated a program to improve the aerodynamics of heavy vehicles through wind tunnel testing, computational modeling, and on-road evaluations. That activity is described in a separate multi-year plan; therefore, emphasis in this document will be on tires, drive trains, and braking systems. Recent, dramatic fluctuations in diesel fuel prices have emphasized the importance of effecting savings in truck fuel economy by implementing new component designs and materials.

  1. Braking the Gas in the beta Pictoris Disk

    E-Print Network [OSTI]

    Rodrigo Fernández; Alexis Brandeker; Yanqin Wu

    2006-01-11

    (Abridged) The main sequence star beta Pictoris hosts the best studied circumstellar disk to date. Nonetheless, a long-standing puzzle has been around since the detection of metallic gas in the disk: radiation pressure from the star should blow the gas away, yet the observed motion is consistent with Keplerian rotation. In this work we search for braking mechanisms that can resolve this discrepancy. We find that all species affected by radiation force are heavily ionized and dynamically coupled into a single fluid by Coulomb collisions, reducing the radiation force on species feeling the strongest acceleration. For a gas of solar composition, the resulting total radiation force still exceeds gravity, while a gas of enhanced carbon abundance could be self-braking. We also explore two other braking agents: collisions with dust grains and neutral gas. Grains surrounding beta Pic are photoelectrically charged to a positive electrostatic potential. If a significant fraction of the grains are carbonaceous (10% in the midplane and larger at higher altitudes), ions can be slowed down to satisfy the observed velocity constraints. For neutral gas to brake the coupled ion fluid, we find the minimum required mass to be $\\approx$ 0.03 $M_\\earth$, consistent with observed upper limits of the hydrogen column density, and substantially reduced relative to previous estimates. Our results favor a scenario in which metallic gas is generated by grain evaporation in the disk, perhaps during grain-grain collisions. We exclude a primordial origin for the gas, but cannot rule out the possibility of its production by falling evaporating bodies near the star. We discuss the implications of this work for observations of gas in other debris disks.

  2. The Roles of Discs for Planetary Systems

    E-Print Network [OSTI]

    Li-Chin Yeh; Ing-Guey Jiang

    2007-01-29

    It is known that the discs are detected for some of the extra-solar planetary systems. It is also likely that there was a disc mixing with planets and small bodies while our Solar System was forming. From our recent results, we conclude that the discs play two roles: the gravity makes planetary systems more chaotic and the drag makes planetary systems more resonant.

  3. SPINDOWN OF ISOLATED NEUTRON STARS: GRAVITATIONAL WAVES OR MAGNETIC BRAKING?

    SciTech Connect (OSTI)

    Staff, Jan E.; Jaikumar, Prashanth; Chan, Vincent; Ouyed, Rachid

    2012-05-20

    We study the spindown of isolated neutron stars from initially rapid rotation rates, driven by two factors: (1) gravitational wave emission due to r-modes and (2) magnetic braking. In the context of isolated neutron stars, we present the first study including self-consistently the magnetic damping of r-modes in the spin evolution. We track the spin evolution employing the RNS code, which accounts for the rotating structure of neutron stars for various equations of state. We find that, despite the strong damping due to the magnetic field, r-modes alter the braking rate from pure magnetic braking for B {<=} 10{sup 13} G. For realistic values of the saturation amplitude {alpha}{sub sat}, the r-mode can also decrease the time to reach the threshold central density for quark deconfinement. Within a phenomenological model, we assess the gravitational waveform that would result from r-mode-driven spindown of a magnetized neutron star. To contrast with the persistent signal during the spindown phase, we also present a preliminary estimate of the transient gravitational wave signal from an explosive quark-hadron phase transition, which can be a signal for the deconfinement of quarks inside neutron stars.

  4. Real-Time Dynamic Brake Assessment Proof of Concept Final Report

    SciTech Connect (OSTI)

    Lascurain, Mary Beth [ORNL; Franzese, Oscar [ORNL; Capps, Gary J [ORNL

    2011-11-01

    This proof-of-concept research was performed to explore the feasibility of using real-world braking data from commercial motor vehicles to make a diagnosis of brake condition similar to that of the performance-based brake tester (PBBT). This was done by determining the relationship between pressure and brake force (P-BF), compensating for the gross vehicle weight (GVW). The nature of this P-BF relationship (e.g., low braking force for a given brake application pressure) may indicate brake system problems. In order to determine the relationship between brake force and brake application pressure, a few key parameters of duty cycle information were collected. Because braking events are often brief, spanning only a few seconds, a sample rate of 10 Hz was needed. The algorithm under development required brake application pressure and speed (from which deceleration was calculated). Accurate weight estimation was also needed to properly derive the braking force from the deceleration. In order to ensure that braking force was the predominant factor in deceleration for the segments of data used in analysis, the data was screened for grade as well. Also, the analysis needed to be based on pressures above the crack pressure. The crack pressure is the pressure below which the individual brakes are not applied due the nature of the mechanical system. This value, which may vary somewhat from one wheel end to another, is approximately 10 psi. Therefore, only pressures 15 psi and above were used in the analysis. The Department of Energy s Medium Truck Duty Cycle research has indicated that under the real-world circumstances of the test vehicle brake pressures of up to approximately 30 psi can be expected. Several different types of data were collected during the testing task of this project. Constant-pressure stopping tests were conducted at several combinations of brake application pressure (15, 20, 25, and 30 psi), load conditions (moderately and fully laden), and speeds (20 and 30 mph). Data was collected at 10 Hz. Standard and stepped-pressure performance-based brake tests with brake pressure transducers were performed for each loading condition. The stepped-pressure test included the constant-pressure intervals of brake application at 15, 20, 25, and 30 psi. The PBBT data files included 10 Hz streaming data collected during the testing of each axle. Two weeks of real-world duty cycle (driving and braking) data was also collected at 10 Hz. Initial analysis of the data revealed that the data collected in the field (i.e., day-to-day operations) provided the same information as that obtained from the controlled tests. Analysis of the data collected revealed a strong linear relationship between brake application pressure and deceleration for given GVWs. As anticipated, initial speed was not found to be a significant factor in the deceleration-pressure relationship, unlike GVW. The positive results obtained from this proof of concept test point to the need for further research to expand this concept. A second phase should include testing over a wider range of speeds and include medium brake application pressures in addition to the low pressures tested in this research. Testing on multiple vehicles would also be of value. This future phase should involve testing to determine how degradation of braking performance affects the pressure-deceleration relationship.

  5. ARM - Front Page

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantity ofkandz-cm11 Comments? WeDatastreamstps DocumentationAtlanticENAField Participants Campaign Details News FieldgovFront Page

  6. Are Low Surface Brightness Discs Young?

    E-Print Network [OSTI]

    Paolo Padoan; Raul Jimenez; Vincenzo Antonuccio-Delogu

    1996-09-12

    We reconsider the problem of the age of the stellar discs of late-type Low Surface Brightness (LSB) galaxies by making use of a new IMF recently derived from numerical fluid dynamical simulations (Padoan, Nordlund and Jones, 1997). While a Miller-Scalo IMF cannot adequately describe the photometric properties of LSBs, when we apply the new Padoan et al. (1997) IMF to a simple exponential disc model with parameters appropriate to LSBs, we get excellent fits of the colors and color gradients. We then conclude that: a) The star formation history of LSB disc galaxies can be described by an initial burst of a few times $10^7$ yr followed by a quiescent period with only sporadic star formation; b) LSBs' discs are not young. The age of the LSB disc galaxies for which colors have been measured are all larger than about 10 Gyr$.

  7. Tachyon cosmology, supernovae data and the Big Brake singularity

    E-Print Network [OSTI]

    Z. Keresztes; L. Á. Gergely; V. Gorini; U. Moschella; A. Yu. Kamenshchik

    2009-04-21

    We compare the existing observational data on type Ia Supernovae with the evolutions of the universe predicted by a one-parameter family of tachyon models which we have introduced recently in paper \\cite{we-tach}. Among the set of the trajectories of the model which are compatible with the data there is a consistent subset for which the universe ends up in a new type of soft cosmological singularity dubbed Big Brake. This opens up yet another scenario for the future history of the universe besides the one predicted by the standard $\\Lambda$CDM model.

  8. Adaptive Torque Control of Electro-Rheological Fluid Brakes Used in Active Knee Rehabilitation Devices

    E-Print Network [OSTI]

    Mavroidis, Constantinos

    1 Adaptive Torque Control of Electro-Rheological Fluid Brakes Used in Active Knee Rehabilitation-rheological fluid (ERF) based variable resistance brakes that are used in compact and portable rehabilitation Control, Actuators for Rehabilitation Robotics I. INTRODUCTION Electro-rheological fluids (ERFs

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

    E-Print Network [OSTI]

    Coimbatore Subramanian, Shankar

    2004-09-30

    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...

  10. On The Use of Eddy Current Brakes as Tunable, Fast Turn-On Viscous Dampers For Haptic Rendering

    E-Print Network [OSTI]

    Hayward, Vincent

    On The Use of Eddy Current Brakes as Tunable, Fast Turn-On Viscous Dampers For Haptic RenderingGill University, Montr´eal, Canada ABSTRACT We describe the use of eddy current brakes as fast turn-on, tunable, linear dampers for haptic rendering using a prototype haptic device outfitted with eddy current brakes

  11. A nonextensive view of the stellar braking indices

    E-Print Network [OSTI]

    de Freitas, D B; Soares, B B; Silva, J R P

    2015-01-01

    The present work is based on a description for the angular mometum loss rate due to magnetic braking for main-sequence stars on the relationship between stellar rotation and age. In general, this loss rate denoted by $\\mathrm dJ/\\mathrm dt$ depends on angular velocity $\\Omega$ in the form $\\mathrm dJ/\\mathrm dt\\propto\\Omega^{q}$, where $q$ is a parameter extracted from nonextensive statistical mechanics. Already, in context of stellar rotation, this parameter is greater than unity and it is directly related to the braking index. For $q$ equal to unity, the scenario of saturation of the magnetic field is recovered, otherwise $q$ indicates an unsaturated field. This new approach have been proposed and investigated by de Freitas \\& De Medeiros for unsaturated field stars. In present work, we propose a nonextensive approach for the stellar rotational evolution based on the Reiners \\& Mohanthy model. In this sense, we developed a nonextensive version of Reiners \\& Mohanthy torque and also compare this ...

  12. Magnetic Field Amplification via Protostellar Disc Dynamos

    E-Print Network [OSTI]

    Dyda, Sergei; Ustyugova, Galina V; Koldoba, Alexander V; Wasserman, Ira

    2015-01-01

    We model the generation of a magnetic field in a protostellar disc using an \\alpha-dynamo and perform axisymmetric magnetohydrodynamics (MHD) simulations of a T Tauri star. We find that for small values of the dimensionless dynamo parameter $\\alpha_d$ the poloidal field grows exponentially at a rate ${\\sigma} \\propto {\\Omega}_K \\sqrt{\\alpha_d}$ , before saturating to a value $\\propto \\sqrt{\\alpha_d}$ . The dynamo excites dipole and octupole modes, but quadrupole modes are suppressed, because of the symmetries of the seed field. Initial seed fields too weak to launch MHD outflows are found to grow sufficiently to launch winds with observationally relevant mass fluxes of order $10^{-9} M_{\\odot}/\\rm{yr}$ for T Tauri stars. For large values of $\\alpha_d$ magnetic loops are generated over the entire disc. These quickly come to dominate the disc dynamics and cause the disc to break up due to the magnetic pressure.

  13. Slug pellet spreading: the double-disc performances available with a single disc spreader

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    1 Slug pellet spreading: the double-disc performances available with a single disc spreader D for slug pellets application. The principal aim of this paper is to show the chosen way to reach spreading pellets 1 Introduction In France, slugs are considered as a harmful destroyer for crops. Their activities

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

    E-Print Network [OSTI]

    Picha, Dale Louis

    1994-01-01

    ) in 1940, incorporates two components into geometric design, a perception-response time (PRT) component and a braking distance component. Because of the importance of sight distance on highways, previous research has questioned the assumptions of these two...

  15. Injection Timing Effects on Brake Fuel Conversion Efficiency and Engine System's Respones 

    E-Print Network [OSTI]

    McLean, James Elliott

    2011-10-21

    Societal concerns on combustion-based fuel consumption are ever-increasing. With respect to internal combustion engines, this translates to a need to increase brake fuel conversion efficiency (BFCE). Diesel engines are a relatively efficient...

  16. A study of factors affecting foot movement time in a braking maneuver 

    E-Print Network [OSTI]

    Berman, Andrea Helene

    1994-01-01

    The nature of foot movement time (MT) in an actual braking maneuver and in a stationary vehicle was investigated regarding the effects of age and gender of the driver and nature of the stimulus to which the driver was ...

  17. Combined fast valving and braking resistor application to improve transient stability 

    E-Print Network [OSTI]

    Chen, Jen-Yeu Thomas

    1982-01-01

    COMBINED FAST VALVING AND BRAKING RESISTOR APPLICATION TO IMPROVE TRANSIENT STABILITY A Thesis by Submitted to the Graduate College of' Texas A&M University in Partial fulfillment of the requirement for the degree of MASTER OF SCIENCE May... 1982 Major Subjecta Electrical Engineering COMBINED FAST VALVING AND BRAKING RESISTOR APPLICATION TO IMPROVE TRANSIENT STABILITY A Thesis by Approved as to style and content by& herman oY mm ee ad of' De tment Member May 1982 ABSTRACT...

  18. Disc valve for sampling erosive process streams

    DOE Patents [OSTI]

    Mrochek, J.E.; Dinsmore, S.R.; Chandler, E.W.

    1986-01-07

    A four-port disc valve is described for sampling erosive, high temperature process streams. A rotatable disc defining opposed first and second sampling cavities rotates between fired faceplates defining flow passageways positioned to be alternatively in axial alignment with the first and second cavities. Silicon carbide inserts and liners composed of [alpha] silicon carbide are provided in the faceplates and in the sampling cavities to limit erosion while providing lubricity for a smooth and precise operation when used under harsh process conditions. 1 fig.

  19. On Jentzsch sets of functions analytic in the unit disc

    E-Print Network [OSTI]

    2015-10-14

    On Jentzsch sets of functions analytic in the. unit disc. Alexandre Eremenko. Sometime 1993. Dear Lee: Let f be an analytic function in the unit disc U = {z : |z|

  20. Braking index of isolated uniformly rotating magnetized pulsars

    E-Print Network [OSTI]

    Hamil, Oliver; Urbanec, Martin; Urbancova, Gabriela

    2015-01-01

    Isolated pulsars are rotating neutron stars with accurately measured angular velocities $\\Omega$, and their time derivatives which show unambiguously that the pulsars are slowing down. Although the exact mechanism of the spin-down is a question of debate in detail, the commonly accepted view is that it arises through emission of magnetic dipole radiation (MDR) from a rotating magnetized body. Other processes, including the emission of gravitational radiation, and of relativistic particles (pulsar wind), are also being considered. The calculated energy loss by a rotating pulsar with a constant moment of inertia is assumed proportional to a model dependent power of $\\Omega$. This relation leads to the power law $\\dot{\\Omega}$ = -K $\\Omega^{\\rm n}$ where $n$ is called the braking index. The MDR model predicts $n$ exactly equal to 3. Selected observations of isolated pulsars provide rather precise values of $n$, individually accurate to a few percent or better, in the range 1$ <$ n $ < $ 2.8, which is consi...

  1. Disc valve for sampling erosive process streams

    DOE Patents [OSTI]

    Mrochek, J.E.; Dinsmore, S.R.; Chandler, E.W.

    1984-08-16

    This is a patent for a disc-type, four-port sampling valve for service with erosive high temperature process streams. Inserts and liners of ..cap alpha..-silicon carbide respectively, in the faceplates and in the sampling cavities, limit erosion while providing lubricity for a smooth and precise operation. 1 fig.

  2. Ocean fronts trigger high latitude phytoplankton blooms

    E-Print Network [OSTI]

    Taylor, John R.

    Density fronts are ubiquitous features of the upper ocean. Here, numerical simulations show that restratification at fronts inhibits vertical mixing, triggering phytoplankton blooms in low-light conditions. The stability ...

  3. Cosmic-ray propagation at small scale: a support for protostellar disc formation

    E-Print Network [OSTI]

    Padovani, Marco; Hennebelle, Patrick; Commercon, Benoît; Joos, Marc

    2015-01-01

    As long as magnetic fields remain frozen into the gas, the magnetic braking prevents the formation of protostellar discs. This condition is subordinate to the ionisation fraction characterising the inmost parts of a collapsing cloud. The ionisation level is established by the number and the energy of the cosmic rays able to reach these regions. Adopting the method developed in our previous studies, we computed how cosmic rays are attenuated as a function of column density and magnetic field strength. We applied our formalism to low- and high-mass star formation models obtained by numerical simulations of gravitational collapse that include rotation and turbulence. In general, we found that the decoupling between gas and magnetic fields, condition allowing the collapse to go ahead, occurs only when the cosmic-ray attenuation is taken into account with respect to a calculation in which the cosmic-ray ionisation rate is kept constant. We also found that the extent of the decoupling zone also depends on the dust ...

  4. Broad reprocessed Balmer emission from warped accretion discs

    E-Print Network [OSTI]

    Sheng-Miao Wu; Ting-Gui Wang; Xiao-Bo Dong

    2008-07-11

    Double peaked broad emission lines in active galactic nuclei are generally considered to be formed in an accretion disc. In this paper, we compute the profiles of reprocessing emission lines from a relativistic, warped accretion disc around a black hole in order to explore the possibility that certain asymmetries in the double-peaked emission line profile which can not be explained by a circular Keplerian disc may be induced by disc warping. The disc warping also provides a solution for the energy budget in the emission line region because it increases the solid angle of the outer disc portion subtended to the inner portion of the disc. We adopted a parametrized disc geometry and a central point-like source of ionizing radiation to capture the main characteristics of the emission line profile from such discs. We find that the ratio between the blue and red peaks of the line profiles becoming less than unity can be naturally predicted by a twisted warped disc, and a third peak can be produced in some cases. We show that disc warping can reproduce the main features of multi-peaked line profiles of four active galactic nuclei from the Sloan Digital Sky Survey.

  5. Operations & Maintenance Best Practices Guide: Front Matter

    Broader source: Energy.gov [DOE]

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

  6. The Front End Fermi National Accelerator Lab

    E-Print Network [OSTI]

    McDonald, Kirk

    The Front End MAP Review Fermi National Accelerator Lab August 24-26, 2010 Harold G. Kirk Brookhaven National Laboratory #12;August 2426, 2010 MAP ReviewFront End Harold G. Kirk ReviewFront End Harold G. Kirk 3 The Muon Collider/Neutrino Factory

  7. Testing thermal reprocessing in AGN accretion discs

    E-Print Network [OSTI]

    E. M. Cackett; K. Horne; H. Winkler

    2007-06-11

    The thermal reprocessing hypothesis in AGN, where EUV/X-ray photons are reprocessed by the accretion disc into optical/UV photons, predicts wavelength-dependent time delays between the optical continuum at different wavelengths. Recent photometric monitoring by Sergeev et al. has shown that the time-delay is observed in 14 AGN, and generally seen to increase with increasing wavelength, as predicted in the reprocessing scenario. We fit the observed time delays and optical spectral energy distribution using a disc reprocessing model. The model delivers estimates for the nuclear reddening, the product of black hole mass times accretion rate, and the distance to each object. However, the distances at face value give H_0 = 44 +/- 5 km/s/Mpc - a factor of 1.6 smaller than generally accepted. We discuss the implications of this on the reprocessing model.

  8. Initial results using Eddy Current Brakes as Fast Turn-on, Programmable Physical Dampers for Haptic Rendering

    E-Print Network [OSTI]

    Hayward, Vincent

    Initial results using Eddy Current Brakes as Fast Turn-on, Programmable Physical Dampers for Haptic Machines McGill University, Montr´eal, Qu´ebec, Canada ABSTRACT We demonstrate the use of eddy current propose an alternate method to create damping in a haptic interface that uses eddy current brakes. 2 EDDY

  9. Energy-Saving Control of an Unstable Valve with a MR Brake QingHui Yuan and Perry Y. Li

    E-Print Network [OSTI]

    Li, Perry Y.

    as a brake does not imply heat reduction. In this paper, we propose a new type of actuator in which a dual lead to heat reduction. In [6], we use a dual-solenoid actuator and design a controller to minimizeEnergy-Saving Control of an Unstable Valve with a MR Brake QingHui Yuan and Perry Y. Li Abstract

  10. REPORT on the TRUCK BRAKE LINING WORKSHOP and FLEET OPERATORS' SURVEY

    SciTech Connect (OSTI)

    Blau, P.J.

    2003-02-03

    The report summarizes what transpired during brake linings-related workshop held at the Fall 2003 meeting of the Technology and Maintenance Council (TMC) in Charlotte, NC. The title of the workshop was ''Developing a Useful Friction Material Rating System''. It was organized by a team consisting of Peter Blau (Oak Ridge National Laboratory), Jim Britell (National Highway Traffic Safety Administration), and Jim Lawrence (Motor and Equipment Manufacturers Association). The workshop was held under the auspices of TMC Task Force S6 (Chassis), chaired by Joseph Stianche (Sanderson Farms, Inc.). Six invited speakers during the morning session provided varied perspectives on testing and rating aftermarket automotive and truck brake linings. They were: James R. Clark, Chief Engineer, Foundation Brakes and Wheel Equipment, Dana Corporation, Spicer Heavy Axle and Brake Division; Charles W. Greening, Jr, President, Greening Test Labs; Tim Duncan, General Manager, Link Testing Services;Dennis J. McNichol, President, Dennis NationaLease; Jim Fajerski, Business Manager, OE Sales and Applications Engineering, Federal Mogul Corporation; and Peter J. Blau, Senior Materials Development Engineer, Oak Ridge National Laboratory. The afternoon break-out sessions addressed nine questions concerning such issues as: ''Should the federal government regulate aftermarket lining quality?''; ''How many operators use RP 628, and if so, what's good or bad about it?''; and ''Would there be any value to you of a vocation-specific rating system?'' The opinions of each discussion group, consisting of 7-9 participants, were reported and consolidated in summary findings on each question. Some questions produced a greater degree of agreement than others. In general, the industry seems eager for more information that would allow those who are responsible for maintaining truck brakes to make better, more informed choices on aftermarket linings. A written fleet operator survey was also conducted during the TMC meeting. Twenty-one responses were received, spanning fleet sizes between 12 and 170,000 vehicles. Responses are summarized in a series of tables separated into responses from small (100 or fewer powered vehicles), medium (101-1000 vehicles), and large fleets (>1000 vehicles). The vast majority of fleets do their own brake maintenance, relying primarily on experience and lining manufactures to select aftermarket linings. At least half of the responders are familiar to some extent with TMC Recommended Practice 628 on brake linings, but most do not use this source of test data as the sole criterion to select linings. Significant shortfalls in the applicability of TMC RP 628 to certain types of brake systems were noted.

  11. System for lubrication of a brake air compressor associated with a turbocharged internal combustion engine

    SciTech Connect (OSTI)

    Spencer, J.C.

    1992-10-13

    This patent describes a system for use with a vehicle which includes a turbocharged internal combustion engine having a lubricating system wherein lubricating oil from an engine oil reservoir is circulated within the engine and also to and from an associated brake system air compressor which supplies compressed air for operation of the vehicle air braking system. This patent describes improvement in passing supercharged air to an oil crankcase of the air compressor to cause lubricating oil to drain therefrom and return to the engine oil reservoir.

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

    E-Print Network [OSTI]

    Kroeger, Timothy H

    2013-09-19

    The brake torque of a direct-injection diesel engine is known to plateau over a range of injection timings. Injection timing affects the engine’s ignition delay and the fractions of fuel which burn in premixed and diffusion modes. Therefore...

  13. Goddard Earth Sciences Data and Information Services Center (GES DISC) http://disc.gsfc.nasa.gov

    E-Print Network [OSTI]

    ://disc.gsfc.nasa.gov NASA Goddard Space Flight Center Code 610.2 Greenbelt, MD 20771 USA README Document for A Multi-Sensor products that now include quality flags. Updated all products with DOI metadata. Gerald Manipon #12;Table

  14. Galactic disc warps due to intergalactic accretion flows onto the disc

    E-Print Network [OSTI]

    M. Lopez-Corredoira; J. Betancort-Rijo; J. E. Beckman

    2007-06-11

    The accretion of the intergalactic medium onto the gaseous disc is used to explain the generation of galactic warps. A cup-shaped distortion is expected, due to the transmission of the linear momentum; but, this effect is small for most incident inflow angles and the predominant effect turns out to be the transmission of angular momentum, i.e. a torque giving an integral-sign shaped warp. The torque produced by a flow of velocity ~100 km/s and baryon density ~10^{-25} kg/m^3, which is within the possible values for the intergalactic medium, is enough to generate the observed warps and this mechanism offers quite a plausible explanation. The inferred rate of infall of matter, ~1 M_sun/yr, to the Galactic disc that this theory predicts agrees with the quantitative predictions of chemical evolution resolving key issues, notably the G-dwarf problem. Sanchez-Salcedo (2006) suggests that this mechanism is not plausible because it would produce a dependence of the scaleheight of the disc with the Galactocentric azimuth in the outer disc, but rather than being an objection this is another argument in favour of the mechanism because this dependence is actually observed in our Galaxy.

  15. 1995-2006 Tsinghua Tongfang Optical Disc Co., Ltd. All rights reserved. 1995-2006 Tsinghua Tongfang Optical Disc Co., Ltd. All rights reserved.

    E-Print Network [OSTI]

    Chen, Jiquan

    © 1995-2006 Tsinghua Tongfang Optical Disc Co., Ltd. All rights reserved. #12;© 1995-2006 Tsinghua Tongfang Optical Disc Co., Ltd. All rights reserved. #12;© 1995-2006 Tsinghua Tongfang Optical Disc Co., Ltd. All rights reserved. #12;© 1995-2006 Tsinghua Tongfang Optical Disc Co., Ltd. All rights reserved

  16. 1995-2006 Tsinghua Tongfang Optical Disc Co., Ltd. All rights reserved. 1995-2006 Tsinghua Tongfang Optical Disc Co., Ltd. All rights reserved.

    E-Print Network [OSTI]

    Zhang, Ke-Min

    © 1995-2006 Tsinghua Tongfang Optical Disc Co., Ltd. All rights reserved. #12;© 1995-2006 Tsinghua Tongfang Optical Disc Co., Ltd. All rights reserved. #12;© 1995-2006 Tsinghua Tongfang Optical Disc Co., Ltd. All rights reserved. #12;© 1995-2006 Tsinghua Tongfang Optical Disc Co., Ltd. All rights reserved

  17. 1995-2004 Tsinghua Tongfang Optical Disc Co., Ltd. All rights reserved. 1995-2004 Tsinghua Tongfang Optical Disc Co., Ltd. All rights reserved.

    E-Print Network [OSTI]

    Qian, Weihong

    © 1995-2004 Tsinghua Tongfang Optical Disc Co., Ltd. All rights reserved. #12;© 1995-2004 Tsinghua Tongfang Optical Disc Co., Ltd. All rights reserved. #12;© 1995-2004 Tsinghua Tongfang Optical Disc Co., Ltd. All rights reserved. #12;© 1995-2004 Tsinghua Tongfang Optical Disc Co., Ltd. All rights reserved

  18. 1995-2004 Tsinghua Tongfang Optical Disc Co., Ltd. All rights reserved. 1995-2004 Tsinghua Tongfang Optical Disc Co., Ltd. All rights reserved.

    E-Print Network [OSTI]

    Zhang, Meirong

    © 1995-2004 Tsinghua Tongfang Optical Disc Co., Ltd. All rights reserved. #12;© 1995-2004 Tsinghua Tongfang Optical Disc Co., Ltd. All rights reserved. #12;© 1995-2004 Tsinghua Tongfang Optical Disc Co., Ltd. All rights reserved. #12;© 1995-2004 Tsinghua Tongfang Optical Disc Co., Ltd. All rights reserved

  19. ORBITAL AND MASS RATIO EVOLUTION OF PROTOBINARIES DRIVEN BY MAGNETIC BRAKING

    SciTech Connect (OSTI)

    Zhao, Bo; Li, Zhi-Yun

    2013-01-20

    The majority of stars reside in multiple systems, especially binaries. The formation and early evolution of binaries is a longstanding problem in star formation that is not yet fully understood. In particular, how the magnetic field observed in star-forming cores shapes the binary characteristics remains relatively unexplored. We demonstrate numerically, using an MHD version of the ENZO AMR hydro code, that a magnetic field of the observed strength can drastically change two of the basic quantities that characterize a binary system: the orbital separation and mass ratio of the two components. Our calculations focus on the protostellar mass accretion phase, after a pair of stellar 'seeds' have already formed. We find that in dense cores magnetized to a realistic level, the angular momentum of the material accreted by the protobinary is greatly reduced by magnetic braking. Accretion of strongly braked material shrinks the protobinary separation by a large factor compared to the non-magnetic case. The magnetic braking also changes the evolution of the mass ratio of unequal-mass protobinaries by producing material of low specific angular momentum that accretes preferentially onto the more massive primary star rather than the secondary. This is in contrast with the preferential mass accretion onto the secondary previously found numerically for protobinaries accreting from an unmagnetized envelope, which tends to drive the mass ratio toward unity. In addition, the magnetic field greatly modifies the morphology and dynamics of the protobinary accretion flow. It suppresses the traditional circumstellar and circumbinary disks that feed the protobinary in the non-magnetic case; the binary is fed instead by a fast collapsing pseudodisk whose rotation is strongly braked. The magnetic braking-driven inward migration of binaries from their birth locations may be constrained by high-resolution observations of the orbital distribution of deeply embedded protobinaries, especially with ALMA and JVLA.

  20. FrontYard *** UpstairsLand

    E-Print Network [OSTI]

    Rosenthal, Jeffrey S.

    Kitchen log[2] Dining Vegetable Embankment RiverShall OutsidePen InsidePen button FrontBarn Windmill [3

  1. Helices in the wake of precipitation fronts

    E-Print Network [OSTI]

    Shibi Thomas; Istvan Lagzi; Ferenc Molnar Jr; Zoltan Racz

    2013-08-30

    A theoretical study of the emergence of helices in the wake of precipitation fronts is presented. The precipitation dynamics is described by the Cahn-Hilliard equation and the fronts are obtained by quenching the system into a linearly unstable state. Confining the process onto the surface of a cylinder and using the pulled-front formalism, our analytical calculations show that there are front solutions that propagate into the unstable state and leave behind a helical structure. We find that helical patterns emerge only if the radius of the cylinder R is larger than a critical value R>R_c, in agreement with recent experiments.

  2. Dynamo-generated turbulence and out ows from accretion discs

    E-Print Network [OSTI]

    Brandenburg, Axel

    kinetic and magnetic energies, and, subsequently, into heat via ohmic and viscous heating. Both in the Sun, DK-2100 Copenhagen  , Denmark Local hydromagnetic simulations of accretion-disc turbulence currently which to draw energy. One such example is in the context of accretion discs (Brandenburg et al. 1995

  3. Type II Migration: Varying Planet Mass and Disc Viscosity

    E-Print Network [OSTI]

    Richard G. Edgar

    2008-07-03

    This paper continues an earlier study of giant planet migration, examining the effect of planet mass and disc viscosity on the migration rate. We find that the migration rate of a gap-opening planet varies systematically with the planet's mass, as predicted in our earlier work. However, the variation with disc viscosity appears to be much weaker than expected.

  4. The age of Taurus - environmental effects on disc lifetimes

    E-Print Network [OSTI]

    Rees, Jon M; Bell, C P M; Jeffries, R D; Naylor, Tim

    2015-01-01

    Using semi-empirical isochrones, we find the age of the Taurus star-forming region to be 3-4 Myr. Comparing the disc fraction in Taurus to young massive clusters suggests discs survive longer in this low density environment. We also present a method of photometrically de-reddening young stars using $iZJH$ data.

  5. Front End G4beamline simulation update Front End G4beamline simulation update

    E-Print Network [OSTI]

    McDonald, Kirk

    1 Front End G4beamline simulation update Front End G4beamline simulation update Pavel Snopok University of California Riverside September 14, 2010 #12;2 Front End G4beamline simulation update More yields per incident proton. Energy deposition study in G4beamline is underway. All numerical results

  6. Hipparcos and the Age of the Galactic Disc

    E-Print Network [OSTI]

    Raul Jimenez; Chris Flynn

    1997-09-22

    We have used the Hipparcos satellite colour magnitude diagram to determine the age of the Galactic disc. We first measure the metallicities of Hipparcos giants using DDO photometry (H{\\o}g & Flynn 1997). With accurate metallicities and distances we compute the minimum age of the Galactic disc as $11\\pm1$ Gyr using the colour of the reddest clump stars as a function of metallicity. In conjunction with the new ages derived for Globular Clusters using the same method (Jimenez et al 1996) we show that any delay between the formation of the halo and the disc was only 2-3 Gyr. Since disc galaxies may have been detected to redshifts as high as $z=3.15$ (Lu, Sargent and Barlow 1997) an age for our own Galactic disc of 11 Gyr favours open or non-zero $\\Lambda$ cosmological models. We show that a Reimers mass-loss law is sufficient to explain the morphology of the red clump.

  7. Light front distribution of the chiral condensate

    E-Print Network [OSTI]

    Lei Chang; Craig D. Roberts; Sebastian M. Schmidt

    2013-09-19

    The pseudoscalar projection of the pion's Poincare'-covariant Bethe-Salpeter amplitude onto the light-front may be understood to provide the probability distribution of the chiral condensate within the pion. Unlike the parton distribution amplitudes usually considered and as befitting a collective effect, this condensate distribution receives contributions from all Fock space components of the pion's light-front wave-function. We compute this condensate distribution using the Dyson-Schwinger equation (DSE) framework and show the result to be a model-independent feature of quantum chromodynamics (QCD). Our analysis establishes that this condensate is concentrated in the neighbourhood of the boundaries of the distribution's domain of support. It thereby confirms the dominant role played by many-particle Fock states within the pion's light-front wave function in generating the chiral condensate on the light-front and verifies that light-front longitudinal zero modes do not play a material role in that process.

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

    E-Print Network [OSTI]

    Hopkins, Jennifer Susan

    1995-01-01

    This simulator experiment is a preliminary study examining the effects of different auditory signals on braking force and reaction time in a rear-end collision warning system. A driving simulator was built in which subjects operated a computer...

  9. Galactic disc warps due to intergalactic accretion flows onto the disc

    E-Print Network [OSTI]

    López-Corredoira, M; Beckman, J E

    2007-01-01

    The accretion of the intergalactic medium onto the gaseous disc is used to explain the generation of galactic warps. A cup-shaped distortion is expected, due to the transmission of the linear momentum; but, this effect is small for most incident inflow angles and the predominant effect turns out to be the transmission of angular momentum, i.e. a torque giving an integral-sign shaped warp. The torque produced by a flow of velocity ~100 km/s and baryon density ~10^{-25} kg/m^3, which is within the possible values for the intergalactic medium, is enough to generate the observed warps and this mechanism offers quite a plausible explanation. The inferred rate of infall of matter, ~1 M_sun/yr, to the Galactic disc that this theory predicts agrees with the quantitative predictions of chemical evolution resolving key issues, notably the G-dwarf problem. Sanchez-Salcedo (2006) suggests that this mechanism is not plausible because it would produce a dependence of the scaleheight of the disc with the Galactocentric azim...

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

    E-Print Network [OSTI]

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

    2014-10-23

    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.

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

    SciTech Connect (OSTI)

    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)

    2013-09-01

    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.

  12. Back Cover Front Cover Office of Continuing

    E-Print Network [OSTI]

    Goodman, Robert M.

    Back Cover Front Cover Office of Continuing Professional Education 2012­2013 Professional Landscape of Golf Course Irrigation Systems (p. 13) · Basics of Turf Management (p. 21) · Turfgrass Establishment (p

  13. ZERO SETS OF POLYNOMIALS UNIVALENT IN THE UNIT DISC

    E-Print Network [OSTI]

    Hartmann, Frederick

    ZERO SETS OF POLYNOMIALS UNIVALENT IN THE UNIT DISC ALAN GLUCHOFF AND FREDERICK HARTMANN 1 AND FREDERICK HARTMANN amount of turning of the image curve allowed), and a condition eventually known as close

  14. Instabilities in Circumstellar Discs Charles F. Gammie 1

    E-Print Network [OSTI]

    Gammie, Charles F.

    . Observation gives only broad constraints in the form of timescales for disc dispersal (e.g. Strom 1994 in the last few years, detailed below. The shear stress is often characterized via a dimensionless ff = W r

  15. Light front Casimir effect at finite temperature

    E-Print Network [OSTI]

    P. L. M. Rodrigues; Silvana Perez; Danilo T. Alves; Van Sérgio Alves; Charles R. Silva

    2015-01-06

    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 conditions imposed at fixed light front times manifests in the thermal part of the energy and entropy, showing that in the classical limit the Casimir entropy decreases linearly with the temperature (not becoming independent of the temperature as expected), and also that the Kirchhoff theorem is not respected.

  16. Angular momentum of disc galaxies with a lognormal density distribution

    E-Print Network [OSTI]

    Marr, John Herbert

    2015-01-01

    Whilst most galaxy properties scale with galaxy mass, similar scaling relations for angular momentum are harder to demonstrate. A lognormal (LN) density distribution for disc mass provides a good overall fit to the observational data for disc rotation curves for a wide variety of galaxy types and luminosities. In this paper, the total angular momentum J and energy $\\vert{}$E$\\vert{}$ were computed for 38 disc galaxies from the published rotation curves and plotted against the derived disc masses, with best fit slopes of 1.683$\\pm{}$0.018 and 1.643$\\pm{}$0.038 respectively, using a theoretical model with a LN density profile. The derived mean disc spin parameter was $\\lambda{}$=0.423$\\pm{}$0.014. Using the rotation curve parameters V$_{max}$ and R$_{max}$ as surrogates for the virial velocity and radius, the virial mass estimator $M_{disc}\\propto{}R_{max}V_{max}^2$ was also generated, with a log-log slope of 1.024$\\pm{}$0.014 for the 38 galaxies, and a proportionality constant ${\\lambda{}}^*=1.47\\pm{}0.20\\time...

  17. The migration of gas giant planets in gravitationally unstable discs

    E-Print Network [OSTI]

    Stamatellos, Dimitris

    2015-01-01

    Planets form in the discs of gas and dust that surround young stars. It is not known whether gas giant planets on wide orbits form the same way as Jupiter or by fragmentation of gravitationally unstable discs. Here we show that a giant planet, which has formed in the outer regions of a protostellar disc, initially migrates fast towards the central star (migration timescale ~10,000 yr) while accreting gas from the disc. However, in contrast with previous studies, we find that the planet eventually opens up a gap in the disc and the migration is essentially halted. At the same time, accretion-powered radiative feedback from the planet, significantly limits its mass growth, keeping it within the planetary mass regime (i.e. below the deuterium burning limit) at least for the initial stages of disc evolution. Giant planets may therefore be able to survive on wide orbits despite their initial fast inward migration, shaping the environment in which terrestrial planets that may harbour life form.

  18. Developments on the CENS Structural Health Monitoring Front

    E-Print Network [OSTI]

    2009-01-01

    on the CENS Structural Health Monitoring Front D. Skolnik,Introduction: Structural Health Monitoring (SHM) Systems

  19. Developments on the CENS Structural Health Monitoring Front

    E-Print Network [OSTI]

    2007-01-01

    on the CENS Structural Health Monitoring Front D. Skolnik,Introduction: Structural Health Monitoring (SHM) Systems

  20. QCD and Light-Front Dynamics

    SciTech Connect (OSTI)

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

    2011-01-10

    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.

  1. Concave Accretion Discs and X-ray Reprocessing

    E-Print Network [OSTI]

    Eric G. Blackman

    1999-03-16

    Spectra of Seyfert Is are commonly modelled as emission from an X-ray illuminated flat accretion disc orbiting a central black hole. This provides both a reprocessed and direct component of the X-ray emission as required by observations of individual objects and possibly a fraction of the cosmological X-ray background. There is some observational motivation to at least consider the role that an effectively concave disc surface might play: (1) a reprocessed fraction $\\gsim 1/2$ in some Seyferts and possibly in the X-ray background, and (2) the commonality of a sharp iron line peak for Seyferts at 6.4KeV despite a dependence of peak location on inclination angle for flat disc models. Here it is shown that a concave disc may not only provide a larger total fraction of reprocessed photons, but can also reprocess a much larger fraction of photons in its outer regions when compared to a flat disc. This reduces the sensitivity of the 6.4KeV peak location to the inner disc inclination angle because the outer regions are less affected by Doppler and gravitational effects. If the X-ray source is isotropic, the reprocessed fraction is directly determined by the concavity. If the X-ray source is anisotropic, the location of iron line peak can still be determined by concavity but the total reflected fraction need not be as large as for the isotropic emitter case. The geometric calculations herein are applicable to general accretion disc systems illuminated from the center.

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

    SciTech Connect (OSTI)

    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

    1998-01-01

    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.

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

    DOE Patents [OSTI]

    Rau, Scott James

    2013-01-29

    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.

  4. Gap formation and stability in non-isothermal protoplanetary discs

    E-Print Network [OSTI]

    Les, Robert

    2015-01-01

    Several observations of transition discs show lopsided dust-distributions. A potential explanation is the formation of a large-scale vortex acting as a dust-trap at the edge of a gap opened by a giant planet. Numerical models of gap-edge vortices have thus far employed locally isothermal discs, but the theory of this vortex-forming or `Rossby wave' instability was originally developed for adiabatic discs. We generalise the study of planetary gap stability to non-isothermal discs using customised numerical simulations of disc-planet systems where the planet opens an unstable gap. We include in the energy equation a simple cooling function with cooling timescale $t_c=\\beta\\Omega_k^{-1}$, where $\\Omega_k$ is the Keplerian frequency, and examine the effect of $\\beta$ on the stability of gap edges and vortex lifetimes. We find increasing $\\beta$ lowers the growth rate of non-axisymmetric perturbations, and the dominant azimuthal wavenumber $m$ decreases. We find a quasi-steady state consisting of one large-scale, ...

  5. Silicate features in Galactic and extragalactic post-AGB discs

    E-Print Network [OSTI]

    Gielen, C; Van Winckel, H; Evans, T Lloyd; Woods, P M; Kemper, F; Marengo, M; Meixner, M; Sloan, G C; Tielens, A G G M

    2011-01-01

    Aims. In this paper we study the Spitzer and TIMMI2 infrared spectra of post-AGB disc sources, both in the Galaxy and the LMC. Using the observed infrared spectra we determine the mineralogy and dust parameters of the discs, and look for possible differences between the Galactic and extragalactic sources. Methods. Modelling the full spectral range observed allows us to determine the dust species present in the disc and different physical parameters such as grain sizes, dust abundance ratios, and the dust and continuum temperatures. Results. We find that all the discs are dominated by emission features of crystalline and amorphous silicate dust. Only a few sample sources show features due to CO2 gas or carbonaceous molecules such as PAHs and C60 fullerenes. Our analysis shows that dust grain processing in these discs is strong, resulting in large average grain sizes and a very high crystallinity fraction. However, we do not find any correlations between the derived dust parameters and properties of the central...

  6. Generation of galactic disc warps due to intergalactic accretion flows onto the disc

    E-Print Network [OSTI]

    M. Lopez-Corredoira; J. Betancort-Rijo; J. E. Beckman

    2002-02-07

    A new method is developed to calculate the amplitude of the galactic warps generated by a torque due to external forces. This takes into account that the warp is produced as a reorientation of the different rings which constitute the disc in order to compensate the differential precession generated by the external force, yielding a uniform asymptotic precession for all rings. Application of this method to gravitational tidal forces in the Milky Way due to the Magellanic Clouds leads to a very low amplitude of the warp. If the force were due to an extragalactic magnetic field, its intensity would have to be very high, to generate the observed warps. An alternative hypothesis is explored: the accretion of the intergalactic medium over the disk. A cup-shaped distortion is expected, due to the transmission of the linear momentum; but, this effect is small and the predominant effect turns out to be the transmission of angular momentum, i.e. a torque giving an integral-sign shape warp. The torque produced by a flow of velocity ~100 km/s and baryon density \\~10^{-25} kg/m^3 is enough to generate the observed warps and this mechanism offers quite a plausible explanation. First, because this order of accretion rate is inferred from other processes observed in the Galaxy, notably its chemical evolution. The inferred rate of infall of matter, ~1 solar-mass/yr, to the Galactic disc that this theory predicts agrees with the quantitative predictions of this chemical evolution resolving key issues, notably the G-dwarf problem. Second, because the required density of the intergalactic medium is within the range of values compatible with observation. By this mechanism, we can explain the warp phenomenon in terms of intergalactic accretion flows onto the disk of the galaxy.

  7. Density waves in the shearing sheet III. Disc heating

    E-Print Network [OSTI]

    B. Fuchs

    2001-04-25

    The problem of dynamical heating of galactic discs by spiral density waves is discussed using the shearing sheet model. The secular evolution of the disc is described quantitatively by a diffusion equation for the distribution function of stars in the space spanned by integrals of motion of the stars, in particular the radial action integral and an integral related to the angular momentum. Specifically, disc heating by a succession of transient, `swing amplified' density waves is studied. It is shown that such density waves lead predominantly to diffusion of stars in radial action space. The stochastical changes of angular momenta of the stars and the corresponding stochastic changes of the guiding centre radii of the stellar orbits induced by this process are much smaller.

  8. Energy deposition update Front End phone meeting

    E-Print Network [OSTI]

    McDonald, Kirk

    Energy deposition update P. Snopok Front End phone meeting March 31, 2015 #12;MARS · Modified geometry is strongly desired · Energy change is via RF kick at the center of the cavity ­ MARS invokes in ICOOL/G4beamline · How thick the beampipe and shielding around (if any) should be ­ energy deposition

  9. ibm.com/redbooks Front cover

    E-Print Network [OSTI]

    Westall, James M.

    ibm.com/redbooks Front cover IBM XIV Storage System: Architecture, Implementation, and Usage Organization IBM XIV Storage System: Architecture, Implementation, and Usage September 2009 SG24-7659-01 #12 with IBM Corp. Second Edition (September 2009) This edition applies to Version 10, Release 1, of the XIV

  10. ibm.com/redbooks Front cover

    E-Print Network [OSTI]

    Hickman, Mark

    ibm.com/redbooks Front cover IBM System Blue Gene Solution: Application Development Gary L. Mullen Organization IBM System Blue Gene Solution: Application Development June 2007 SG24-7179-04 #12;© Copyright Restricted Rights -- Use, duplication or disclosure restricted by GSA ADP Schedule Contract with IBM Corp

  11. Does the thermal disc instability operate in active galactic nuclei?

    E-Print Network [OSTI]

    L. Burderi; A. R. King; E. Szuszkiewicz

    1998-03-19

    We examine all possible stationary, optically thick, geometrically thin accretion disc models relevant for active galactic nuclei (AGN) and identify the physical regimes in which they are stable against the thermal-viscous hydrogen ionization instability. Self-gravity and irradiation effects are included. We find that most if not all AGN discs are unstable. Observed AGN therefore represent the outburst state, although some or all quasars could constitute a steady population having markedly higher fuelling rates than other AGN. It has important implications for the AGN mass supply and for the presence of supermassive black holes in nearby spirals.

  12. Experimental investigation of magnetic anisotropy in spin vortex discs

    SciTech Connect (OSTI)

    Garraud, N. Arnold, D. P.

    2014-05-07

    We present experimental 2D vector vibrating sample magnetometer measurements to demonstrate the shape anisotropy effects occurring in micrometer-diameter supermalloy spin vortex discs. Measurements made for different disc sizes and orientations confirm the out-of-plane susceptibility is several orders of magnitude smaller than the in-plane susceptibility. These results validate with a high certitude that spin vortices with high diameter to thickness ratio retain in-plane-only magnetization, even when subjected to fields in the out-of-plane direction. These results contribute to further computational simulations of the dynamics of spin vortex structures in colloidal suspensions where external fields may be applied in any arbitrary direction.

  13. On the fate of the Antarctic Slope Front and the origin of the Weddell Front

    E-Print Network [OSTI]

    Naveira Garabato, Alberto

    Oceanography: Physical: Fronts and jets; 4532 Oceanography: Physical: General circulation; 4536 Oceanography: Physical: Hydrography; 4207 Oceanography: General: Arctic and Antarctic oceanography; 4223 Oceanography: General: Descriptive and regional oceanography; KEYWORDS: topographic interaction, Weddell Scotia

  14. Hybrid: Braking

    Alternative Fuels and Advanced Vehicles Data Center [Office of Energy Efficiency and Renewable Energy (EERE)]

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page on Google Bookmark EERE: Alternative Fuels Data Center Home Page on Delicious Rank EERE: Alternative Fuels Data Center Home PageBlenderBusiness Case for E85CaliforniaCleanUNITEDNREL

  15. Hybrid: Braking

    Alternative Fuels and Advanced Vehicles Data Center [Office of Energy Efficiency and Renewable Energy (EERE)]

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page on Google Bookmark EERE: Alternative Fuels Data Center Home Page on Delicious Rank EERE: Alternative Fuels Data Center Home PageBlenderBusiness Case for E85CaliforniaCleanUNITEDNRELButton

  16. Uncertainty-Enabled Design of a Rocket Sled Track Switch Drs. Jordan E. Massad and Matthew R. Brake

    E-Print Network [OSTI]

    Uncertainty-Enabled Design of a Rocket Sled Track Switch Drs. Jordan E. Massad and Matthew R. Brake Sandia National Laboratories, New Mexico Rocket sled tracks provide a dynamically rich environment acceleration profile, the switch closes to complete a circuit for instrument activation. Preliminary tests

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

    E-Print Network [OSTI]

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

    2010-01-01

    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 ...

  18. Energy-Saving Control of an Unstable Valve with a MR Brake QingHui Yuan and Perry Y. Li

    E-Print Network [OSTI]

    Li, Perry Y.

    Energy-Saving Control of an Unstable Valve with a MR Brake QingHui Yuan and Perry Y. Li Abstract controller is then developed to achieve position tracking and energy-saving. Simulation verifies that using. INTRODUCTION Energy-saving is an important issue in fluid power indus- try. The research of energy efficiency

  19. A laboratory plasma experiment for studying magnetic dynamics of accretion discs and jets

    E-Print Network [OSTI]

    Hsu, Scott

    A laboratory plasma experiment for studying magnetic dynamics of accretion discs and jets S. C. Hsu into the magnetic dynamics of accretion discs and jets. A high-speed multiple-frame CCD camera reveals images of the formation and helical instability of a collimated plasma, similar to MHD models of disc jets, and also

  20. Front-end electronics and trigger systems - status and challenges

    E-Print Network [OSTI]

    Spieler, Helmuth G

    2008-01-01

    of the 12th Workshop on Electronics For LHC and Future19-24, 2007 Front-end electronics and trigger systems –about a revolution in front-end electronics for large- scale

  1. Developments on the CENS Structural Health Monitoring Front (SEI 2)

    E-Print Network [OSTI]

    2006-01-01

    on the CENS Structural Health Monitoring Front M. Kohler, J.framework for structural health monitoring (SHM). hea lth

  2. ALMA observations of the kinematics and chemistry of disc formation

    E-Print Network [OSTI]

    Lindberg, Johan E; Brinch, Christian; Haugbølle, Troels; Bergin, Edwin A; Harsono, Daniel; Persson, Magnus V; Visser, Ruud; Yamamoto, Satoshi

    2014-01-01

    Context: The R CrA cloud hosts a handful of Class 0/I low-mass young stellar objects. The chemistry and physics at scales $>500$ AU in this cloud are dominated by the irradiation from the nearby Herbig Be star R CrA. The luminous large-scale emission makes it necessary to use high-resolution spectral imaging to study the chemistry and dynamics of the inner envelopes and discs of the protostars. Aims: We aim to better understand the structure of the inner regions of these protostars and in particular the interplay between the chemistry and the presence of discs. Methods: Using Atacama Large Millimeter/submillimeter Array (ALMA) high-resolution spectral imaging interferometry observations, we study the molecular line and dust continuum emission at submillimetre wavelengths. Results: We detect dust continuum emission from four circumstellar discs around Class 0/I objects within the R CrA cloud. Towards IRS7B we detect C$^{17}$O emission showing a rotation curve consistent with a Keplerian disc with a well-define...

  3. NIHAO III: The constant disc gas mass conspiracy

    E-Print Network [OSTI]

    Stinson, G S; Wang, L; Macciò, A V; Herpich, J; Bradford, J D; Quinn, T R; Wadsley, J; Keller, B

    2015-01-01

    We show that the cool gas masses of galactic discs reach a steady state that lasts many Gyr after their last major merger in cosmological hydrodynamic simulations. The mass of disc gas, M$_{\\rm gas}$, depends upon a galaxy halo's spin and virial mass, but not upon stellar feedback. Halos with low spin have high star formation efficiency and lower disc gas mass. Similarly, lower stellar feedback leads to more star formation so the gas mass ends up nearly the same irregardless of stellar feedback strength. Even considering spin, the M$_{\\rm gas}$ relation with halo mass, M$_{200}$ only shows a factor of 3 scatter. The M$_{\\rm gas}$--M$_{200}$ relation show a break at M$_{200}$=$2\\times10^{11}$ M$_\\odot$ that corresponds to an observed break in the M$_{\\rm gas}$--M$_\\star$ relation. The constant disc mass stems from a shared halo gas density profile in all the simulated galaxies. In their outer regions, the profiles are isothermal. Where the profile rises above $n=10^{-3}$ cm$^{-3}$, the gas readily cools and th...

  4. Fast migration of low-mass planets in radiative discs

    E-Print Network [OSTI]

    Pierens, Arnaud

    2015-01-01

    Low-mass planets are known to undergo Type I migration and this process must have played a key role during the evolution of planetary systems. Analytical formulae for the disc torque have been derived assuming that the planet evolves on a fixed circular orbit. However, recent work has shown that in isothermal discs, a migrating protoplanet may also experience dynamical corotation torques that scale with the planet drift rate. The aim of this study is to examine whether dynamical corotation torques can also affect the migration of low-mass planets in non-isothermal discs. We performed 2D radiative hydrodynamical simulations to examine the orbital evolution outcome of migrating protoplanets as a function of disc mass. We find that a protoplanet can enter a fast migration regime when it migrates in the direction set by the entropy-related horseshoe drag and when the Toomre stability parameter is less than a threshold value below which the horseshoe region contracts into a tadpole-like region. In that case, an un...

  5. The dust grain size - stellar luminosity trend in debris discs

    E-Print Network [OSTI]

    Pawellek, Nicole

    2015-01-01

    The cross section of material in debris discs is thought to be dominated by the smallest grains that can still stay in bound orbits despite the repelling action of stellar radiation pressure. Thus the minimum (and typical) grain size $s_\\text{min}$ is expected to be close to the radiation pressure blowout size $s_\\text{blow}$. Yet a recent analysis of a sample of Herschel-resolved debris discs showed the ratio $s_\\text{min}/s_\\text{blow}$ to systematically decrease with the stellar luminosity from about ten for solar-type stars to nearly unity in the discs around the most luminous A-type stars. Here we explore this trend in more detail, checking how significant it is and seeking to find possible explanations. We show that the trend is robust to variation of the composition and porosity of dust particles. For any assumed grain properties and stellar parameters, we suggest a recipe of how to estimate the "true" radius of a spatially unresolved debris disc, based solely on its spectral energy distribution. The r...

  6. Integrated Optic Disc and Cup Segmentation with Deep Learning

    E-Print Network [OSTI]

    Stephan, Frank

    - exaggerated inputs emphasizing disc pallor without blood vessel obstruction, as well as the degree of vessel challenging cases for manual inspection. Tests on two large real-world databases, including the publicly on predicting glaucoma from other retinal image characteristics such as vessel distribution [1], FFT

  7. Tracking the Salt Front Page 1 Name __________________________________________ Date____________________

    E-Print Network [OSTI]

    Lance, Veronica P.

    , moving the salt front inland. Scientists track the salt front using Hudson River Miles, abbreviated HRM, is HRM 0. The George Washington Bridge is at HRM 12, the city of Kingston at HRM 91. Ocean tides reach the Federal Dam in Troy at HRM 153. Using the graph "Hudson River Salt Front: Average Location by Month

  8. MAGNETIC BRAKING FORMULATION FOR SUN-LIKE STARS: DEPENDENCE ON DIPOLE FIELD STRENGTH AND ROTATION RATE

    SciTech Connect (OSTI)

    Matt, Sean P.; Pinsonneault, Marc H.; Greene, Thomas P. E-mail: kmac@ucar.edu E-mail: thomas.p.greene@nasa.gov

    2012-08-01

    We use two-dimensional axisymmetric magnetohydrodynamic simulations to compute steady-state solutions for solar-like stellar winds from rotating stars with dipolar magnetic fields. Our parameter study includes 50 simulations covering a wide range of relative magnetic field strengths and rotation rates, extending from the slow- and approaching the fast-magnetic-rotator regimes. Using the simulations to compute the angular momentum loss, we derive a semi-analytic formulation for the external torque on the star that fits all of the simulations to a precision of a few percent. This formula provides a simple method for computing the magnetic braking of Sun-like stars due to magnetized stellar winds, which properly includes the dependence on the strength of the magnetic field, mass loss rate, stellar radius, surface gravity, and spin rate, and which is valid for both slow and fast rotators.

  9. Light-front chiral effective field theory

    SciTech Connect (OSTI)

    Mathiot, J.-F. [Laboratoire de Physique Corpusculaire (France)] [Laboratoire de Physique Corpusculaire (France); Tsirova, N. A., E-mail: ntsirova@ssu.samara.ru [Samara State University (Russian Federation)

    2013-11-15

    We propose a general framework to calculate the nonperturbative structure of relativistic bound state systems. The state vector of the bound state is calculated in the covariant formulation of light-front dynamics. In this scheme, the state vector is defined on the light front of general position {omega} {center_dot} x = 0, where {omega} is an arbitrary light-like four-vector. This enables a strict control of any violation of rotational invariance. The state vector is then decomposed in Fock components. Our formalism is applied to the description of the nucleon properties at low energy, in chiral perturbation theory. We also show that the use of a recently proposed regularization scheme, the so-called Taylor-Lagrange regularization scheme, is very adequate in order to treat divergences in this nonperturbative framework.

  10. Front contact solar cell with formed emitter

    SciTech Connect (OSTI)

    Cousins, Peter John

    2014-11-04

    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.

  11. Front contact solar cell with formed emitter

    DOE Patents [OSTI]

    Cousins, Peter John (Menlo Park, CA)

    2012-07-17

    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.

  12. Pentan isomers compound flame front structure

    SciTech Connect (OSTI)

    Mansurov, Z.A.; Mironenko, A.W.; Bodikov, D.U.; Rachmetkaliev, K.N.

    1995-08-13

    The fuels (hexane, pentane, diethyl ether) and conditions investigated in this study are relevant to engine knock in spark- ignition engines. A review is provided of the field of low temperature hydrocarbon oxidation. Studies were made of radical and stable intermediate distribution in the front of cool flames: Maximum concentrations of H atoms and peroxy radicals were observed in the luminous zone of the cool flame front. Peroxy radicals appear before the luminous zone at 430 K due to diffusion. H atoms were found in cool flames of butane and hexane. H atoms diffuses from the luminous zone to the side of the fresh mixture, and they penetrate into the fresh mixture to a small depth. Extension of action sphear of peroxy radicals in the fresh mixture is much greater than that of H atoms due to their small activity and high concentrations.

  13. Front-lighted shadowgraphic method and apparatus

    SciTech Connect (OSTI)

    Not Available

    1982-02-11

    High contrast silhouette images of a substantially opaque object are obtained using front illumination techniques. The object is frontally illuminated by light of a first polarization. A frontal surface of the object reflects the incident light to an observation station. The polarization of incident light bypassing the object and incident on a background is changed. The background light is reflected to the observation station, and the intensity of one of the two, differently polarized, reflected images is substantially reduced with respect to the other. Apparatus for carrying out the method includes a first polarizer for polarizing frontally incident illuminating light, a second polarizer behind the object and a reflective surface behind the second polarizer. A polarization analyzer, located in front of the object, is used to extinguish one of the two reflected images. Apparatus for carrying out the invention in instruments having a polarized light source and a polarization analyzer includes a combination of a polarizing material, for contacting a rear surface of the object, and a reflective surface provided adjacent the rear surface of the polarizing material. The combination is applied to the rear surface of the object. Back-surface mirrors of pleochroic substrates, applied to thin film physical vapor-deposited electronic circuit elements, enable front lighted shadow-graphic imaging of the elements.

  14. Migration of massive black hole binaries in self--gravitating accretion discs: Retrograde versus prograde

    E-Print Network [OSTI]

    Constanze Roedig; Alberto Sesana

    2013-07-24

    We study the interplay between mass transfer, accretion and gravitational torques onto a black hole binary migrating in a self-gravitating, retrograde circumbinary disc. A direct comparison with an identical prograde disc shows that: (i) because of the absence of resonances, the cavity size is a factor a(1+e) smaller for retrograde discs; (ii) nonetheless the shrinkage of a circular binary semi--major axis, a, is identical in both cases; (iii) a circular binary in a retrograde disc remains circular while eccentric binaries grow more eccentric. For non-circular binaries, we measure the orbital decay rates and the eccentricity growth rates to be exponential as long as the binary orbits in the plane of its disc. Additionally, for these co-planar systems, we find that interaction (~ non--zero torque) stems only from the cavity edge plus a(1+e) in the disc, i.e. for dynamical purposes, the disc can be treated as a annulus of small radial extent. We find that simple 'dust' models in which the binary- disc interaction is purely gravitational can account for all main numerical results, both for prograde and retrograde discs. Furthermore, we discuss the possibility of an instability occurring for highly eccentric binaries causing it to leave the disc plane, secularly tilt and converge to a prograde system. Our results suggest that there are two stable configurations for binaries in self-gravitating discs: the special circular retrograde case and an eccentric (e~ 0.6) prograde configuration as a stable attractor.

  15. An alternative approach to viscosity in an accretion disc

    E-Print Network [OSTI]

    R. G. Edgar

    2006-10-02

    Purely hydrodynamic numerical experiments into the evolution of astrophysical discs typically include some sort of viscosity in order to cause accretion. In this paper, we demonstrate an alternative method of implementing viscous forces, with extremely good angular momentum conservation properties. The method is based on altering the cell fluxes, rather than incorporating a viscous force. We test this method on the classical `ring spreading' problem, and demonstrate angular momentum conservation at the $10^{-8}$ level.

  16. Bay Front Biomass Facility | Open Energy Information

    Open Energy Info (EERE)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page on Google Bookmark EERE: Alternative Fuels Data Center Home Page on QA:QA J-E-1 SECTION J APPENDIX ECoop IncIowaWisconsin: EnergyYorkColorado StateWind ProjectVillage,BatonFront Biomass

  17. FRONT BURNER - ISSUE 19 | Department of Energy

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

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page on Google Bookmark EERE: Alternative Fuels Data Center Home Page on Delicious Rank EERE:FinancingPetroleum12, 2015Executive Order14, 2011 CX-006821:forEnergyADVANCEDTO: Ex parteFRONT

  18. A Complete Relativistic Ionized Accretion Disc in Cygnus X-1

    E-Print Network [OSTI]

    A. J. Young; A. C. Fabian; R. R. Ross; Y. Tanaka

    2001-03-14

    The galactic black hole candidate Cygnus X-1 is observed to be in one of two X-ray spectral states; either the low/hard (low soft X-ray flux and a flat power law tail) or high/soft (high blackbody-like soft X-ray flux and a steep power law tail) state. The physical origin of these two states is unclear. We present here a model of an ionized accretion disc, the spectrum of which is blurred by relativistic effects, and fit it to the ASCA, Ginga and EXOSAT data of Cygnus X-1 in both spectral states. We confirm that relativistic blurring provides a much better fit to the low/hard state data and, contrary to some previous results, find the data of both states to be consistent with an ionized thin accretion disc with a reflected fraction of unity extending to the innermost stable circular orbit around the black hole. Our model is an alternative to those which, in the low/hard state, require the accretion disc to be truncated at a few tens of Schwarzschild radii, within which there is a Thomson-thin, hot accretion flow. We suggest a mechanism that may cause the changes in spectral state.

  19. Methanol Along the Path from Envelope to Protoplanetary Disc

    E-Print Network [OSTI]

    Drozdovskaya, Maria N; Visser, Ruud; Harsono, Daniel; van Dishoeck, Ewine F

    2014-01-01

    Interstellar methanol is considered to be a parent species of larger, more complex organic molecules. A physicochemical simulation of infalling parcels of matter is performed for a low-mass star-forming system to trace the chemical evolution from cloud to disc. An axisymmetric 2D semi-analytic model generates the time-dependent density and velocity distributions, and full continuum radiative transfer is performed to calculate the dust temperature and the UV radiation field at each position as a function of time. A comprehensive gas-grain chemical network is employed to compute the chemical abundances along infall trajectories. Two physical scenarios are studied, one in which the dominant disc growth mechanism is viscous spreading, and another in which continuous infall of matter prevails. The results show that the infall path influences the abundance of methanol entering each type of disc, ranging from complete loss of methanol to an enhancement by a factor of > 1 relative to the prestellar phase. Critical ch...

  20. Fronts and fluctuations at a critical surface

    E-Print Network [OSTI]

    Haim Weissmann; Nadav M. Shnerb; David A. Kessler

    2015-08-14

    The properties of a front between two different phases in the presence of a smoothly inhomogeneous external field that takes its critical value at the crossing point is analyzed. Two generic scenarios are studied. In the first, the system admits a bistable solution and the external field governs the rate in which one phase invades the other. The second mechanism corresponds to a second order transition that, in the case of reactive systems, takes the form of a transcritical bifurcation at the crossing point. We solve for the front shape and its response to external white noise, showing that static properties and also some of the dynamics features cannot distinguish between the two scenarios. The only reliable indicator turns out to be the fluctuation statistics. These take a Gaussian form in the bifurcation case and a double-peak shape in a bistable system. The results of a recent analysis of the morphogenesis process in Drosophila embryos are reanalyzed and we show, in contrast with the interpretation suggested by Krotov et. al., that the plausible underlying dynamics is bistable and not bifurcational.

  1. Front-runners in plant-microbe interactions.

    E-Print Network [OSTI]

    Ronald, Pamela C; Shirasu, Ken

    2012-01-01

    Front-runners in plant–microbe interactions Editorialwww.sciencedirect.com Plants and microbes, abundant in thedetermine if the associated microbes are friends or foes,

  2. Light-front representation of chiral dynamics in peripheral transverse...

    Office of Scientific and Technical Information (OSTI)

    for the peripheral transverse densities as overlap integrals of chiral light-front wave functions, describing the transition of the initial nucleon to soft pion-nucleon...

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

    SciTech Connect (OSTI)

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

    2012-02-16

    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.

  4. Webinar: Testing Oxygen Reduction Reaction Activity with the Rotating Disc Electrode Technique

    Broader source: Energy.gov [DOE]

    Video recording of the Fuel Cell Technologies Office webinar, Testing Oxygen Reduction Reaction Activity with the Rotating Disc Electrode Technique, originally presented on March 12, 2013.

  5. The spectra of accretion discs in low-mass X-ray binaries

    E-Print Network [OSTI]

    R. R. Ross; A. C. Fabian

    1995-11-14

    We present self-consistent models for the radiative transfer in Shakura-Sunyaev accretion discs in bright low-mass X-ray binaries (LMXB). Our calculations include the full effects of incoherent Compton scattering and the vertical temperature structure within the disc, as well as the effects of Doppler blurring and gravitational redshift. We find that the observed X-ray spectra are well fit by exponentially cutoff power-law models. The difference between the observed total spectrum and our calculated disc spectrum should reveal the spectrum of the disc/neutron star boundary layer and other emitting regions considered to be present in LMXB.

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

    DOE Patents [OSTI]

    Cousins, Peter John

    2012-06-26

    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.

  7. 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

  8. Combustion fronts in porous media with two layers Steve Schecter

    E-Print Network [OSTI]

    Schecter, Stephen

    Combustion fronts in porous media with two layers layer 1 layer 2 Steve Schecter North Carolina Subject: Propagation of a combustion front through a porous medium with two parallel layers having different properties. · Each layer admits a traveling combustion wave. · The layers are coupled by heat

  9. Mean stream coordinates structure of the Subantarctic Front: Temperature, salinity,

    E-Print Network [OSTI]

    Luther, Douglas S.

    . The cross-stream structure of along-stream velocity is very nearly symmetric about the jet axisMean stream coordinates structure of the Subantarctic Front: Temperature, salinity, and absolute southwest of Tasmania, at the Subantarctic Front (SAF), is estimated by a stream coordinates analysis

  10. Front velocity in models with quadratic autocatalysis Vladimir K. Vanaga)

    E-Print Network [OSTI]

    Epstein, Irving R.

    Front velocity in models with quadratic autocatalysis Vladimir K. Vanaga) and Irving R. Epstein reaction­diffusion models based on the Oregonator model of the Belousov­Zhabotinsky reaction. Each system the dependence of the front velocity on the diffusion coefficients of X and R, the interconversion rates

  11. NUMERICAL SOLUTION OF THE POLYMER SYSTEM BY FRONT TRACKING

    E-Print Network [OSTI]

    , models two­phase, three­component polymer flooding in an oil reservoir. Two examples are presented, where. Key words and phrases. Front tracking, nonstrictly hyperbolic systems, polymer flooding, dimensionalNUMERICAL SOLUTION OF THE POLYMER SYSTEM BY FRONT TRACKING V. HAUGSE, K. H. KARLSEN, K.--A. LIE

  12. Tidal Dwarf Galaxies: Disc Formation at z=0

    E-Print Network [OSTI]

    Lelli, Federico; Brinks, Elias; McGaugh, Stacy S

    2015-01-01

    Collisional debris around interacting and post-interacting galaxies often display condensations of gas and young stars that can potentially form gravitationally bound objects: Tidal Dwarf Galaxies (TDGs). We summarise recent results on TDGs, which are originally published in Lelli et al. (2015, A&A). We study a sample of six TDGs around three different interacting systems, using high-resolution HI observations from the Very Large Array. We find that the HI emission associated to TDGs can be described by rotating disc models. These discs, however, would have undergone less than one orbit since the time of the TDG formation, raising the question of whether they are in dynamical equilibrium. Assuming that TDGs are in dynamical equilibrium, we find that the ratio of dynamical mass to baryonic mass is consistent with one, implying that TDGs are devoid of dark matter. This is in line with the results of numerical simulations where tidal forces effectively segregate dark matter in the halo from baryonic matter i...

  13. Gas and dust hydrodynamical simulations of massive lopsided transition discs - I. Gas distribution

    E-Print Network [OSTI]

    Zhu, Zhaohuan

    2015-01-01

    Motivated by lopsided structures observed in some massive transition discs, we have carried out 2D numerical simulations to study vortex structure in massive discs, including the effects of disc self-gravity and the indirect force which is due to the displacement of the central star from the barycenter of the system by the lopsided structure. When only the indirect force is included, we confirm the finding by Mittal & Chiang (2015) that the vortex becomes stronger and can be more than two pressure scale heights wide, as long as the disc-to-star mass ratio is >1%. Such wide vortices can excite strong density waves in the disc and therefore migrate inwards rapidly. However, when disc self-gravity is also considered in simulations, self-gravity plays a more prominent role on the vortex structure. We confirm that when the disc Toomre Q parameter is smaller than pi/(2h), where h is the disc's aspect ratio, the vortices are significantly weakened and their inward migration slows down dramatically. Most importan...

  14. TO APPEAR IN MICCAI 2008. Lumbar Disc Localization and Labeling with a

    E-Print Network [OSTI]

    Corso, Jason J.

    ] and recent [2] studies have suggested a need for repeatable quantitative inter- vertebral disc degeneration fragments of disc material to press on the nerve roots in the spinal column. In the clinic, a radiolo- gist, with possible bending of the spinal column (scoliosis) and missing or additional verte- brae [3]. In Figure 1

  15. ACCEPTED AUTHORS' DRAFT, THE FINAL VERSION TO APPEAR IN THE IEEE/ASME TRANSACTIONS ON MECHATRONICS, VOL. 13, NO. 6, 669677, 2008. 1 Eddy Current Brakes for Haptic Interfaces

    E-Print Network [OSTI]

    Hayward, Vincent

    , VOL. 13, NO. 6, 669­677, 2008. 1 Eddy Current Brakes for Haptic Interfaces: Design, Identification describe the design of an eddy current brake for use as programmable viscous damper for haptic interfaces actuators for haptic interfaces. We overview the governing physical relationships, and describe design

  16. On the fragility of nuclear stellar discs against galaxy mergers: surviving photometric and kinematic signatures of nuclear discs

    E-Print Network [OSTI]

    Sarzi, M; Dotti, M

    2015-01-01

    Nuclear stellar discs (NSDs) can help to constrain the assembly history of their host galaxies, as long as we can assume them to be fragile structures that are disrupted during merger events. In this work we investigate the fragility of NSDs by means of N-body simulations reproducing the last phases of a galaxy encounter, when the nuclear regions of the two galaxies merge. For this, we exposed a NSD set in the gravitational potential of the bulge and supermassive black hole of a primary galaxy to the impact of the supermassive black hole from a secondary galaxy. We explored merger events of different mass ratios, from major mergers with a 1:1 mass ratio to intermediate and minor interactions with 1:5 and 1:10 ratios, while considering various impact geometries. We analyse the end results of such mergers from different viewing angles and looked for possible photometric and kinematic signatures of the presence of a disc in the remnant surface density and velocity maps, while adopting detection limits from real ...

  17. Electron g-2 in Light-front Quantization

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

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

    2014-10-01

    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%.

  18. LARGE-SCALE CORONAL PROPAGATING FRONTS IN SOLAR ERUPTIONS AS...

    Office of Scientific and Technical Information (OSTI)

    LARGE-SCALE CORONAL PROPAGATING FRONTS IN SOLAR ERUPTIONS AS OBSERVED BY THE ATMOSPHERIC IMAGING ASSEMBLY ON BOARD THE SOLAR DYNAMICS OBSERVATORY-AN ENSEMBLE STUDY Re-direct...

  19. RF CMOS UWB transmitter and receiver front-end design 

    E-Print Network [OSTI]

    Miao, Meng

    2009-05-15

    The low-cost low-power complementary metal-oxide semiconductor (CMOS) ultra wideband (UWB) transmitter and receiver front-ends based on impulse technology were developed. The CMOS UWB pulse generator with frequency-band ...

  20. The Active Wave-front Sampling based 3D endoscope

    E-Print Network [OSTI]

    Prakash, Hemanth

    2007-01-01

    This thesis investigates the potential of Active Wave-front Sampling (AWS) for real time quantified 3D endoscopy. AWS is a technique by which phase information from an aperture area of a lens is obtained by sampling ...

  1. Global optimization of silicon photovoltaic cell front coatings

    E-Print Network [OSTI]

    Ghebrebrhan, Michael

    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, ...

  2. Home Front as Warfront: African American World War I Drama

    E-Print Network [OSTI]

    Egging, Anna Katherine

    2010-08-31

    This dissertation recovers little-known African American World War I plays that blur the boundary between the home front and warfront. I argue that with this focus, the plays wage their own war for African American citizenship ...

  3. Speed-up of combustion fronts in shear flows

    E-Print Network [OSTI]

    Hamel, Francois

    2011-01-01

    This paper is concerned with the analysis of speed-up of reaction-diffusion-advection traveling fronts in infinite cylinders with periodic boundary conditions. The advection is a shear flow with a large amplitude and the reaction is nonnegative, with either positive or zero ignition temperature. The unique or minimal speeds of the traveling fronts are proved to be asymptotically linear in the flow amplitude as the latter goes to infinity, solving an open problem from \\cite{b}. The asymptotic growth rate is characterized explicitly as the unique or minimal speed of traveling fronts for a limiting degenerate problem, and the convergence of the regular traveling fronts to the degenerate ones is proved for positive ignition temperatures under an additional H{\\"{o}}rmander-type condition on the flow.

  4. Phase front patterns in shape memory alloy strips

    SciTech Connect (OSTI)

    Lagoudas, D.C.; Howard, S.D. [Texas A& M Univ., TX (United States)

    1995-12-31

    Uniaxial thermomechanical tests of Shape Memory Alloy (SMA) Nitinol strips, below the austenitic start temperature, have shown the formation of multiple phase front patterns forming at approximately 45 degrees angle with respect to the applied load. These phase fronts, that separate self-accommodating martensitic variants from detwinned martensite, propagate along the specimen in the direction of applied load, until fully detwinned martensite is developed. Similar patterns of martensitic-austenitic phase fronts occur when the temperature is raised above austenitic finish, and uniaxial loading is applied to the strip specimens. An experimental study of this phenomenon, together with some preliminary modelling results will be presented. In contrast to the above uniform loading case, experimental results and numerical simulations for the propagation of a phase transformation front, induced by an imposed temperature gradient, will also be presented.

  5. Carbon Emissions from Smouldering Peat in Shallow and Strong Fronts 

    E-Print Network [OSTI]

    Rein, Guillermo; Cohen, Simon; Simeoni, Albert

    2009-01-01

    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 ...

  6. Liberation of specific angular momentum through radiation and scattering in relativistic black-hole accretion discs

    E-Print Network [OSTI]

    Adam R. H. Stevens

    2015-07-16

    A key component of explaining the array of galaxies observed in the Universe is the feedback of active galactic nuclei, each powered by a massive black hole's accretion disc. For accretion to occur, angular momentum must be lost by that which is accreted. Electromagnetic radiation must offer some respite in this regard, the contribution for which is quantified in this paper, using solely general relativity, under the thin-disc regime. Herein, I calculate extremised situations where photons are entirely responsible for energy removal in the disc and then extend and relate this to the standard relativistic accretion disc outlined by Novikov & Thorne, which includes internal angular-momentum transport. While there is potential for the contribution of angular-momentum removal from photons to be >~1% out to ~10^4 Schwarzschild radii if the disc is irradiated and maximally liberated of angular momentum through inverse Compton scattering, it is more likely of order 10^2 Schwarzschild radii if thermal emission from the disc itself is stronger. The effect of radiation/scattering is stronger near the horizons of fast-spinning black holes, but, ultimately, other mechanisms must drive angular-momentum liberation/transport in accretion discs.

  7. Meson structure in light-front holographic QCD

    E-Print Network [OSTI]

    Rohit Swarnkar; Dipankar Chakrabarti

    2015-07-06

    We consider the light-front holographic QCD with the light-front wave functions for mesons, modified for massive quarks. We evaluate the wave functions, distribution amplitudes, and form factors for $\\pi$, $\\rho$, $K$, and $J/\\psi$ mesons and photon-to-meson transition form factors for $\\pi$, $\\eta$, and $\\eta^\\prime$. The results are compared with the experimental data, wherever available.

  8. A study of the contrast of a submerged disc using Monte Carlo techniques 

    E-Print Network [OSTI]

    Hagan, Donald Frank

    1980-01-01

    in the simulation of lioht interactions within the Earth's ocean system. Using the Monte Carlo computer program the contrast of a Secchi disc and its ocean background was calculated. A Secchi disc 1s a horizontal disc in the ocean that is v1ewed from the surface... of samples which requires more computation time. Before the advent of high speed computers, the Monte Carlo Method was generally useless because of the massive amount of computation it required. The Monte Carlo Method is fairly simple in application...

  9. A viscous-convective instability in laminar Keplerian thin discs. II. Anelastic approximation

    E-Print Network [OSTI]

    Shakura, N

    2015-01-01

    Using the anelastic approximation of linearised hydrodynamic equations, we investigate the development of axially symmetric small perturbations in thin Keplerian discs. The sixth-order dispersion equation is derived and numerically solved for different values of relevant physical parameters (viscosity, heat conductivity, disc semi-thickness and vertical structure). The analysis reveals the appearance of two overstable modes which split out from the classical Rayleigh inertial modes in a wide range of the parameters in both ionized and neutral gases. These modes have a viscous-convective nature and can serve as a seed for turbulence in astrophysical discs even in the absence of magnetic fields.

  10. 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]

    Carpick, Robert W.

    Hydraulic Drivetrain and Regenerative Braking Team 13: Andrew Brown, Karan Desai, Andrew Mc Pressure Reservior Filter Variable Vane Pump Motor/Pump Hydraulic Accumulators Solenoid Valve Relief Valve Suction Line Since their development in 2006, hydraulic drivetrain systems have gained considerable

  11. Finite element analysis of the effect of up-armouring on the off-road braking and sharp-turn performance

    E-Print Network [OSTI]

    Grujicic, Mica

    Finite element analysis of the effect of up-armouring on the off-road braking and sharp-mobility multi-purpose wheeled vehicle, off-road vehicle performance, finite element modelling and simulations revision for publication on 15 June 2009. DOI: 10.1243/09544070JAUTO1187 Abstract: A comprehensive finite

  12. Low voltage supply system for the very front end readout electronics of the CMS electromagnetic calorimeter

    E-Print Network [OSTI]

    Lustermann, W; Denes, P; Djambazov, L; Dröge, M; Faure, J L; Iliev, Bozhidar Z; Nanov, I; Raykov, P; Shivarov, N

    1999-01-01

    Low voltage supply system for the very front end readout electronics of the CMS electromagnetic calorimeter

  13. Frontal circulation induced by up-front and coastal downwelling winds

    E-Print Network [OSTI]

    consequences to vertical exchanges of tracers and water masses. Keywords Ocean fronts . Wind-front interactionFrontal circulation induced by up-front and coastal downwelling winds Yu-Lin Chang & Lie-Yauw Oey-shelf and depth) circula- tion by downwelling wind in the presence of a prograding front (with isopycnals

  14. INSTABILITY OF MAGNETIZED IONIZATION FRONTS SURROUNDING H II REGIONS

    SciTech Connect (OSTI)

    Kim, Jeong-Gyu; Kim, Woong-Tae, E-mail: jgkim@astro.snu.ac.kr, E-mail: wkim@astro.snu.ac.kr [Center for the Exploration of the Origin of the Universe (CEOU), Astronomy Program, Department of Physics and Astronomy, Seoul National University, Seoul 151-742 (Korea, Republic of)

    2014-12-20

    An ionization front (IF) surrounding an H II region is a sharp interface where a cold neutral gas makes the transition to a warm ionized phase by absorbing UV photons from central stars. We investigate the instability of a plane-parallel D-type IF threaded by parallel magnetic fields, by neglecting the effects of recombination within the ionized gas. We find that weak D-type IFs always have the post-IF magnetosonic Mach number M{sub M2}?1. For such fronts, magnetic fields increase the maximum propagation speed of the IFs, while reducing the expansion factor ? by a factor of 1 + 1/(2?{sub 1}) compared to the unmagnetized case, with ?{sub 1} denoting the plasma beta in the pre-IF region. IFs become unstable to distortional perturbations owing to gas expansion across the fronts, exactly analogous to the Darrieus-Landau instability of ablation fronts in terrestrial flames. The growth rate of the IF instability is proportional linearly to the perturbation wavenumber, as well as the upstream flow speed, and approximately to ?{sup 1/2}. The IF instability is stabilized by gas compressibility and becomes completely quenched when the front is D-critical. The instability is also stabilized by magnetic pressure when the perturbations propagate in the direction perpendicular to the fields. When the perturbations propagate in the direction parallel to the fields, on the other hand, it is magnetic tension that reduces the growth rate, completely suppressing the instability when M{sub M2}{sup 2}<2/(2?{sub 1}?1). When the front experiences an acceleration, the IF instability cooperates with the Rayleigh-Taylor instability to make the front more unstable.

  15. Evolution of Accretion Discs around a Kerr Black Hole using Extended Magnetohydrodynamics

    E-Print Network [OSTI]

    Foucart, Francois; Gammie, Charles F; Quataert, Eliot

    2015-01-01

    Black holes accreting well below the Eddington rate are believed to have geometrically thick, optically thin, rotationally supported accretion discs in which the Coulomb mean free path is large compared to $GM/c^2$. In such an environment, the disc evolution may differ significantly from ideal magnetohydrodynamic predictions. We present non-ideal global axisymmetric simulations of geometrically thick discs around a rotating black hole. The simulations are carried out using a new code ${\\rm\\it grim}$, which evolves a covariant extended magnetohydrodynamics model derived by treating non-ideal effects as a perturbation of ideal magnetohydrodynamics. Non-ideal effects are modeled through heat conduction along magnetic field lines, and a difference between the pressure parallel and perpendicular to the field lines. The model relies on an effective collisionality in the disc from wave-particle scattering and velocity-space (mirror and firehose) instabilities. We find that the pressure anisotropy grows to match the ...

  16. The gas metallicity gradient and the star formation activity of disc galaxies

    E-Print Network [OSTI]

    Tissera, Patricia B; Sillero, Emanuel; Vilchez, Jose M

    2015-01-01

    We study oxygen abundance profiles of the gaseous disc components in simulated galaxies in a hierarchical universe. We analyse the disc metallicity gradients in relation to the stellar masses and star formation rates of the simulated galaxies. We find a trend for galaxies with low stellar masses to have steeper metallicity gradients than galaxies with high stellar masses at z ~0. We also detect that the gas-phase metallicity slopes and the specific star formation rate (sSFR) of our simulated disc galaxies are consistent with recently reported observations at z ~0. Simulated galaxies with high stellar masses reproduce the observed relationship at all analysed redshifts and have an increasing contribution of discs with positive metallicity slopes with increasing redshift. Simulated galaxies with low stellar masses a have larger fraction of negative metallicity gradients with increasing redshift. Simulated galaxies with positive or very negative metallicity slopes exhibit disturbed morphologies and/or have a clo...

  17. NDE1 in the DISC1 pathway: interactions of schizophrenia-related proteins 

    E-Print Network [OSTI]

    Bradshaw, Nicholas James

    2009-01-01

    The Disrupted-In-Schizophrenia 1 (DISC1) gene is one of the most established risk genes for psychiatric illness currently being studied, having originally been identified as being directly disrupted by a balanced chromosomal ...

  18. A collagen-GAG matrix for the growth of intervertebral disc tissue

    E-Print Network [OSTI]

    Hastreiter, Dawn (Dawn Marie), 1973-

    2002-01-01

    Intervertebral disc (IVD) degeneration and herniation is a significant problem, more so in the aviation field. The IVD also changes during spaceflight. Current treatments for IVD problems can have unfavorable long-term ...

  19. The pseudo-photosphere model for the continuum emission of gaseous discs

    E-Print Network [OSTI]

    Vieira, Rodrigo G; Bjorkman, Jon E

    2015-01-01

    We investigate the continuum emission of viscous decretion discs around Be stars in this paper. The results obtained from non-LTE (local thermodynamic equilibrium) radiative transfer models show two regimes in the disc surface brightness profile: an inner optically thick region, which behaves as a pseudo-photosphere with a wavelength-dependent size, and an optically thin tenuous outer part, which contributes with about a third of the total flux. The isophotal shape of the surface brightness is well described by elliptical contours with an axial ratio $b/a=\\cos i$ for inclinations $iemission of gaseous discs. It provides fluxes and spectral slopes at the infrared within an accuracy of $10\\%$ and $5\\%$, respectively, when compared to the numerical results. The model indicates that the infrared spectral slope is mainly determined by both the density radial slope and the disc flaring exponent, being practic...

  20. Global models of planetary system formation in radiatively-inefficient protoplanetary discs

    E-Print Network [OSTI]

    Hellary, Phil

    2011-01-01

    (Abridged) We present the results of N-body simulations of planetary systems formation in radiatively-inefficient disc models, where positive corotation torques may counter the rapid inward migration of low mass planets driven by Lindblad torques. The aim of this work is to examine the nature of planetary systems that arise from oligarchic growth in such discs. We adapt the commonly-used Mercury-6 symplectic integrator by including simple prescriptions for planetary migration (types I and II), planetary atmospheres that enhance the probability of planetesimal accretion by protoplanets, gas accretion onto forming planetary cores, and gas disc dispersal. We perform a suite of simulations for a variety of disc models with power-law surface density and tempera- ture profiles, with a focus on models in which unsaturated corotation torques can drive outward migration of protoplanets. In some models we account for the quenching of corotation torques that arises when planetary orbits become eccentric. Approximately h...

  1. Reprocessed emission from warped accretion discs with application to X-ray iron line profiles

    E-Print Network [OSTI]

    Sean A. Hartnoll; Eric G. Blackman

    1999-08-25

    Flourescent iron line profiles currently provide the best diagnostic for active galactic nuclei (AGN) engine geometries. Here we construct a method for calculating the relativistic iron line profile from an arbitrarily warped accretion disc, illuminated from above and below by hard X-ray sources. This substantially generalises previous calculations of reprocessing by accretion discs by including non-axisymmetric effects. We include a relativistic treatment of shadowing by ray-tracing photon paths along Schwarzchild geodesics. We apply this method to two classes of warped discs, and generate a selection of resulting line profiles. New profile features include the possibility of sharper red, and softer blue fall-offs, a time varying line profile if the warp precesses about the disc, and some differences between `twisted' and `twist-free' warps. We discuss some qualitative implications of the line profiles in the context of Type I and II Seyfert AGN.

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

    SciTech Connect (OSTI)

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

    1995-11-01

    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.

  3. Gravitational instabilities in a protosolar-like disc I: dynamics and chemistry

    E-Print Network [OSTI]

    Evans, M G; Boley, A C; Caselli, P; Durisen, R H; Hartquist, T W; Rawlings, J M C

    2015-01-01

    To date, most simulations of the chemistry in protoplanetary discs have used 1+1D or 2D axisymmetric $\\alpha$-disc models to determine chemical compositions within young systems. This assumption is inappropriate for non-axisymmetric, gravitationally unstable discs, which may be a significant stage in early protoplanetary disc evolution. Using 3D radiative hydrodynamics, we have modelled the physical and chemical evolution of a 0.17 M$_{\\odot}$ self-gravitating disc over a period of 2000 yr. The 0.8 M$_{\\odot}$ central protostar is likely to evolve into a solar-like star, and hence this Class 0 or early Class I young stellar object may be analogous to our early Solar System. Shocks driven by gravitational instabilities enhance the desorption rates, which dominate the changes in gas-phase fractional abundances for most species. We find that at the end of the simulation, a number of species distinctly trace the spiral structure of our relatively low-mass disc, particularly CN. We compare our simulation to that o...

  4. Searching for the metal-weak thick disc in the solar neighbourhood

    E-Print Network [OSTI]

    Bacham E. Reddy; David L. Lambert

    2008-09-05

    An abundance analysis is presented of 60 metal-poor stars drawn from catalogues of nearby stars provided by Ariyanto et al. (2005) and Schuster et al. (2006). In an attempt to isolate a sample of metal-weak thick disc stars, we applied the kinematic criteria $V_{\\rm rot} \\geq 100$ km s$^{-1}$, $|U_{LSR}| \\leq 140$ km s$^{-1}$, and $|W_{LSR}| \\leq 100$ km s$^{-1}$. Fourteen stars satisfying these criteria and having [Fe/H] $\\leq -1.0$ are included in the sample of 60 stars. Eight of the 14 have [Fe/H] $\\geq -1.3$ and may be simply thick disc stars of slightly lower than average [Fe/H]. The other six have [Fe/H] from -1.3 to -2.3 and are either metal-weak thick disc stars or halo stars with kinematics mimicking those of the thick disc. The sample of 60 stars is completed by eight thick disc stars, 20 stars of a hybrid nature (halo or thick disc stars), and 18 stars with kinematics distinctive of the halo.

  5. One-armed spirals in locally isothermal, radially structured self-gravitating discs

    E-Print Network [OSTI]

    Lin, Min-Kai

    2015-01-01

    We describe a new mechanism that leads to the destabilisation of non-axisymmetric waves in astrophysical discs with an imposed radial temperature gradient. This might apply, for example, to the outer parts of protoplanetary discs. We use linear density wave theory to show that non-axisymmetric perturbations generally do not conserve their angular momentum in the presence of a forced temperature gradient. This implies an exchange of angular momentum between linear perturbations and the background disc. In particular, when the disturbance is a low-frequency trailing wave and the disc temperature decreases outwards, this interaction is unstable and leads to the growth of the wave. We demonstrate this phenomenon through numerical hydrodynamic simulations of locally isothermal discs in 2D using the FARGO code and in 3D with the ZEUS-MP and PLUTO codes. We consider radially structured discs with a self-gravitating region which remains stable in the absence of a temperature gradient. However, when a temperature grad...

  6. The young nuclear stellar disc in the SB0 galaxy NGC 1023

    E-Print Network [OSTI]

    Corsini, E M; Pastorello, N; Bontà, E Dalla; Pizzella, A; Portaluri, E

    2015-01-01

    Small kinematically-decoupled stellar discs with scalelengths of a few tens of parsec are known to reside in the centre of galaxies. Different mechanisms have been proposed to explain how they form, including gas dissipation and merging of globular clusters. Using archival Hubble Space Telescope imaging and ground-based integral-field spectroscopy, we investigated the structure and stellar populations of the nuclear stellar disc hosted in the interacting SB0 galaxy NGC 1023. The stars of the nuclear disc are remarkably younger and more metal rich with respect to the host bulge. These findings support a scenario in which the nuclear disc is the end result of star formation in metal enriched gas piled up in the galaxy centre. The gas can be of either internal or external origin, i.e. from either the main disc of NGC 1023 or the nearby satellite galaxy NGC 1023A. The dissipationless formation of the nuclear disc from already formed stars, through the migration and accretion of star clusters into the galactic cen...

  7. Scaling of Quench Front and Entrainment-Related Phenomena

    SciTech Connect (OSTI)

    Aumiller, D. L.; Hourser, R. J.; Holowach, M. J.; Hochreiter, L. E.; Cheung, F-B.

    2002-04-01

    The scaling of thermal hydraulic systems is of great importance in the development of experiments in laboratory-scale test facilities that are used to replicate the response of full-size prototypical designs. One particular phenomenon that is of interest in experimental modeling is the quench front that develops during the reflood phase in a PWR (Pressurized Water Reactor) following a large-break LOCA (Loss of Coolant Accident). The purpose of this study is to develop a scaling methodology such that the prototypical quench front related phenomena can be preserved in a laboratory-scale test facility which may have material, geometrical, fluid, and flow differences as compared to the prototypical case. A mass and energy balance on a Lagrangian quench front control volume along with temporal scaling methods are utilized in developing the quench front scaling groups for a phenomena-specific second-tier scaling analysis. A sample calculation is presented comparing the quench front scaling groups calculated for a prototypical Westinghouse 17 x 17 PWR fuel design and that of the geometry and material configuration used in the FLECHT SEASET series of experiments.

  8. Emergent Mesoscale Phenomena in Magnetized Accretion Disc Turbulence

    E-Print Network [OSTI]

    Simon, Jacob B; Armitage, Philip J

    2012-01-01

    We study how the structure and variability of magnetohydrodynamic (MHD) turbulence in accretion discs converge with domain size. Our results are based on a series of vertically stratified local simulations, computed using the Athena code, that have fixed spatial resolution, but varying radial and azimuthal extent (from \\Delta R = 0.5H to 16H, where H is the vertical scale height). We show that elementary local diagnostics of the turbulence, including the Shakura-Sunyaev {\\alpha} parameter, the ratio of Maxwell stress to magnetic energy, and the ratio of magnetic to fluid stresses, converge to within the precision of our measurements for spatial domains of radial size Lx \\geq 2H. We obtain {\\alpha} = 0.02-0.03, consistent with recent results. Very small domains (Lx = 0.5H) return anomalous results, independent of spatial resolution. The convergence with domain size is only valid for a limited set of diagnostics: larger spatial domains admit the emergence of dynamically important mesoscale structures. In our la...

  9. An Evolutionary Sequence of Expanding Hydrogen Shells in Galaxy Discs

    E-Print Network [OSTI]

    M. Relano; J. E. Beckman; O. Daigle; C. Carignan

    2007-03-16

    Large HI shells, with diameters of hundreds of pc and expansion velocities of 10-20kms-1 are well observed features of local gas rich galaxies. These shells could well be predicted as a result of the impact of OB associations on the ISM, but doubt has been cast on this scenario by the apparent absence of OB stars close to the centres of a large fraction of these shells in recent observations of the SMC. Using Fabry-Perot scanned Halpha emission line mapping of nearby galaxy discs we have detected, in all the HII regions where the observations yield sufficient angular resolution and S:N ratio, dominant Halpha shells with radii a few tens of pc, expanding at velocities of 50-100kms-1. We have applied a simple dynamically consistent framework in which we can extrapolate the properties of the observed Halpha shells to a few 10^7yr after the formation of the OB stars. The framework includes the dynamical inputs of both winds and SNe on the surrounding ISM. The results give quantitative statistical support to the hypothesis that the Halpha emitting shells are generic progenitors of the HI shells. During the time taken for an expanding shell to reach the size of a typical HI shell, the OB association may well lose its most luminous stars so the absence of such stars near the centres of many of the HI shells is well explained in this scenario.

  10. Methods for enhancing mapping of thermal fronts in oil recovery

    DOE Patents [OSTI]

    Lee, D.O.; Montoya, P.C.; Wayland, J.R. Jr.

    1984-03-30

    A method for enhancing the resistivity contrasts of a thermal front in an oil recovery production field as measured by the controlled source audio frequency magnetotelluric (CSAMT) technique is disclosed. This method includes the steps of: (1) preparing a CSAMT-determined topological resistivity map of the production field; (2) introducing a solution of a dopant material into the production field at a concentration effective to alter the resistivity associated with the thermal front; said dopant material having a high cation exchange capacity which might be selected from the group consisting of montmorillonite, illite, and chlorite clays; said material being soluble in the conate water of the production field; (3) preparing a CSAMT-determined topological resistivity map of the production field while said dopant material is moving therethrough; and (4) mathematically comparing the maps from step (1) and step (3) to determine the location of the thermal front. This method is effective with the steam flood, fire flood and water flood techniques.

  11. Methods for enhancing mapping of thermal fronts in oil recovery

    DOE Patents [OSTI]

    Lee, David O. (Albuquerque, NM); Montoya, Paul C. (Albuquerque, NM); Wayland, Jr., James R. (Albuquerque, NM)

    1987-01-01

    A method for enhancing the resistivity contrasts of a thermal front in an oil recovery production field as measured by the CSAMT technique is disclosed. This method includes the steps of: (a) preparing a CSAMT-determined topological resistivity map of the production field; (b) introducing a solution of a dopant material into the production field at a concentration effective to alter the resistivity associated with the thermal front; said dopant material having a high cation exchange capacity which might be selected from the group consisting of montmorillonite, illite, and chlorite clays; said material being soluble in the connate water of the production field; (c) preparing a CSAMT-determined topological resistivity map of the production field while said dopant material is moving therethrough; and (d) mathematically comparing the maps from step (a) and step (c) to determine the location of the thermal front. This method is effective with the steam flood, fire flood and water flood techniques.

  12. Acoustic wave front conjugation in a three-phase media

    E-Print Network [OSTI]

    Pushkina, N I

    2015-01-01

    Acoustic wave front reversal is studied in a sandy marine sediment that contains air bubbles in its fluid fraction. The considered phase conjugation is a four-wave nonlinear parametric sound interaction process caused by nonlinear bubble oscillations which are known to be dominant in acoustic nonlinear interactions in three-phase marine sediments. Two various mechanisms of phase conjugation are studied. One of them is based on the stimulated Raman-type sound scattering on resonance bubble oscillations. The second one is associated with sound interactions with bubble oscillations which frequencies are far from resonance bubble frequencies. Nonlinear equations to solve the wave-front conjugation problem are derived, expressions for acoustic wave amplitudes with a reversed wave front are obtained and compared for various frequencies of the excited bubble oscillations.

  13. Acoustic wave front reversal in a three-phase media

    E-Print Network [OSTI]

    N. I. Pushkina

    2015-03-05

    Acoustic wave front conjugation is studied in a sandy marine sediment that contains air bubbles in its fluid fraction. The considered phase conjugation is a four-wave nonlinear parametric sound interaction process caused by nonlinear bubble oscillations which are known to be dominant in acoustic nonlinear interactions in three-phase marine sediments. Two various mechanisms of phase conjugation are studied. One of them is based on the stimulated Raman-type sound scattering on resonance bubble oscillations. The second one is associated with sound interactions with bubble oscillations which frequencies are far from resonance bubble frequencies. Nonlinear equations to solve the wave-front conjugation problem are derived, expressions for acoustic wave amplitudes with a reversed wave front are obtained and compared for various frequencies of the excited bubble oscillations.

  14. Light-Front Holographic QCD and Emerging Confinement

    E-Print Network [OSTI]

    Stanley J. Brodsky; Guy F. de Teramond; Hans Gunter Dosch; Joshua Erlich

    2015-02-13

    In this report we explore the remarkable connections between light-front dynamics, its holographic mapping to gravity in a higher-dimensional anti-de Sitter (AdS) space, and conformal quantum mechanics. This approach provides new insights into the origin of a fundamental mass scale and the physics underlying confinement dynamics in QCD in the limit of massless quarks. The result is a relativistic light-front wave equation for arbitrary spin with an effective confinement potential derived from a conformal action and its embedding in AdS space. This equation allows for the computation of essential features of hadron spectra in terms of a single scale. The light-front holographic methods described here gives a precise interpretation of holographic variables and quantities in AdS in terms of light-front variables and quantum numbers. This leads to a relation between the AdS wave functions and the boost-invariant light-front wave functions describing the internal structure of hadronic bound states in physical space-time. The pion is massless in the chiral limit and the excitation spectra of relativistic light-quark meson and baryon bound states lie on linear Regge trajectories with identical slopes in the radial and orbital quantum numbers. In the light-front holographic approach described here currents are expressed as an infinite sum of poles, and form factors as a product of poles. At large $q^2$ the form factor incorporates the correct power-law fall-off for hard scattering independent of the specific dynamics and is dictated by the twist. At low $q^2$ the form factor leads to vector dominance. The approach is also extended to include small quark masses. We briefly review in this report other holographic approaches to QCD, in particular top-down and bottom-up models based on chiral symmetry breaking. We also include a discussion of open problems and future applications.

  15. Light-front holographic QCD and emerging confinement

    SciTech Connect (OSTI)

    Brodsky, Stanley J.; de Téramond, Guy F.; Dosch, Hans Günter; Erlich, Joshua

    2015-05-21

    In this study we explore the remarkable connections between light-front dynamics, its holographic mapping to gravity in a higher-dimensional anti-de Sitter (AdS) space, and conformal quantum mechanics. This approach provides new insights into the origin of a fundamental mass scale and the physics underlying confinement dynamics in QCD in the limit of massless quarks. The result is a relativistic light-front wave equation for arbitrary spin with an effective confinement potential derived from a conformal action and its embedding in AdS space. This equation allows for the computation of essential features of hadron spectra in terms of a single scale. The light-front holographic methods described here give a precise interpretation of holographic variables and quantities in AdS space in terms of light-front variables and quantum numbers. This leads to a relation between the AdS wave functions and the boost-invariant light-front wave functions describing the internal structure of hadronic bound-states in physical spacetime. The pion is massless in the chiral limit and the excitation spectra of relativistic light-quark meson and baryon bound states lie on linear Regge trajectories with identical slopes in the radial and orbital quantum numbers. In the light-front holographic approach described here currents are expressed as an infinite sum of poles, and form factors as a product of poles. At large q2 the form factor incorporates the correct power-law fall-off for hard scattering independent of the specific dynamics and is dictated by the twist. At low q2 the form factor leads to vector dominance. The approach is also extended to include small quark masses. We briefly review in this report other holographic approaches to QCD, in particular top-down and bottom-up models based on chiral symmetry breaking. We also include a discussion of open problems and future applications.

  16. Light-front holographic QCD and emerging confinement

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Brodsky, Stanley J.; de Téramond, Guy F.; Dosch, Hans Günter; Erlich, Joshua

    2015-05-21

    In this study we explore the remarkable connections between light-front dynamics, its holographic mapping to gravity in a higher-dimensional anti-de Sitter (AdS) space, and conformal quantum mechanics. This approach provides new insights into the origin of a fundamental mass scale and the physics underlying confinement dynamics in QCD in the limit of massless quarks. The result is a relativistic light-front wave equation for arbitrary spin with an effective confinement potential derived from a conformal action and its embedding in AdS space. This equation allows for the computation of essential features of hadron spectra in terms of a single scale. Themore »light-front holographic methods described here give a precise interpretation of holographic variables and quantities in AdS space in terms of light-front variables and quantum numbers. This leads to a relation between the AdS wave functions and the boost-invariant light-front wave functions describing the internal structure of hadronic bound-states in physical spacetime. The pion is massless in the chiral limit and the excitation spectra of relativistic light-quark meson and baryon bound states lie on linear Regge trajectories with identical slopes in the radial and orbital quantum numbers. In the light-front holographic approach described here currents are expressed as an infinite sum of poles, and form factors as a product of poles. At large q2 the form factor incorporates the correct power-law fall-off for hard scattering independent of the specific dynamics and is dictated by the twist. At low q2 the form factor leads to vector dominance. The approach is also extended to include small quark masses. We briefly review in this report other holographic approaches to QCD, in particular top-down and bottom-up models based on chiral symmetry breaking. We also include a discussion of open problems and future applications.« less

  17. Development of RF CMOS receiver front-ends for ultrawideband 

    E-Print Network [OSTI]

    Guan, Xin

    2009-05-15

    .5dB and a noise figure of 3.3-4.5dB from 3-9.5GHz, while only consuming 9mW power. Based on the distributed amplifier and resistive shunt-feedback amplifier designs, two UWB RF front-ends are developed. One is a distributed LNA-Mixer. Unlike...

  18. On the propagation of a coupled saturation and pressure front

    SciTech Connect (OSTI)

    Vasco, D. W.

    2010-12-01

    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.

  19. Propagating front in an excited granular layer W. Losert,1

    E-Print Network [OSTI]

    Gollub, Jerry P.

    that produces a rapid transition. We measure the front velocity as a function of the applied acceleration and the mechanisms of transitions between phases are of great interest. Although there are no attractive a triggered phase transition that transforms a quiescent disordered phase to an excited granu- lar gas via

  20. Acceleration at shock fronts. Lecture 2 D. B. MELROSE

    E-Print Network [OSTI]

    Melrose, Don

    Fiiica #12;upstream downstream shock Fig. 1.- The changes in fluid velocity and magnetic field across. The upstream magnetic field is at an angle to n,and this changes to $2 in the downstream region. equal front is at rest, with the upstream plasma flowing into it at a velocity ul and the downstream plasma

  1. ON THE FRONT COVER Kristen Barnes | Fifth year

    E-Print Network [OSTI]

    Acton, Scott

    Moul | Third year Sheridan Fuller | Third year Harry Whelchel | Fourth year ON THE BACK COVER Lukef a c t b o ok2012 #12;ON THE FRONT COVER Kristen Barnes | Fifth year Darren Daniels | First year William R. Richardson | Third year Alyson Richardson | Third year Chris Bergin | First year Shakye Jones

  2. Flame front tracking by laser induced fluorescence spectroscopy and advanced

    E-Print Network [OSTI]

    Hamarneh, Ghassan

    surface characteristics in turbulent premixed propane/air combustion," Combustion and Flame 120(4), 407 References and links 1. J. Warnatz, U. Maas, and R.W. Dibble, Combustion - physical and chemical fundamentals, "Characterization of flame front surfaces in turbulent premixed methane/air combustion," Combustion and Flame 101

  3. 1 1999 Rational Software Corporation The View from the Front

    E-Print Network [OSTI]

    Demurjian, Steven A.

    1 ©1999 Rational Software Corporation 3/7/99 R UML The View from the Front James Rumbaugh 9 March 1999 Rational Software Corporation #12; 2 ©1999 Rational Software Corporation 3/7/99 R Evolution Start 1/95 UML 1.3 RTF report 4/99 OMG feedback #12; 3 ©1999 Rational Software Corporation 3/7/99 R UML

  4. Travel Reimbursement Request Form Submit to: Front Desk

    E-Print Network [OSTI]

    Rose, Michael R.

    Travel Reimbursement Request Form Submit to: Front Desk Department of Pharmaceutial Sciences 147 expenses) If travel time does not include overnight stay (between 7AM - 8PM), the traveler should not claim before 11 AM and arrival after 2 PM; dinner - departure before 5 PM. PM and arrival after 7 PM NOTE

  5. Travel Reimbursement Request Form Submit to: Front Desk

    E-Print Network [OSTI]

    Loudon, Catherine

    Travel Reimbursement Request Form Submit to: Front Desk Department of Pharmaceutical Sciences 147 : Maximum: $71.00 (Itemize meal expenses) If travel time does not include overnight stay (between 7AM - 8PM; lunch - departure before 11 AM and arrival after 2 PM; dinner - departure before 5 PM. PM and arrival

  6. Shielded RF Lattice for the Muon Front End Chris Rogers,

    E-Print Network [OSTI]

    McDonald, Kirk

    Shielded RF Lattice for the Muon Front End Chris Rogers, Accelerator Science and Technology Centre (ASTeC), Rutherford Appleton Laboratory #12; Shielded RF Lattice I wanted to remind folks a lot of slides apologies I've tried to break it up a bit #12; Part 1 Shielded Lattice Baseline

  7. Revealing the accretion disc corona in Mrk 335 with multi-epoch X-ray spectroscopy

    E-Print Network [OSTI]

    Keek, L

    2015-01-01

    Active galactic nuclei host an accretion disc with an X-ray producing corona around a supermassive black hole. In bright sources, such as the Seyfert 1 galaxy Mrk 335, reflection of the coronal emission off the accretion disc has been observed. Reflection produces spectral features such as an Fe K$\\alpha$ emission line, which allow for properties of the inner accretion disc and the corona to be constrained. We perform a multi-epoch spectral analysis of all XMM-Newton, Suzaku, and NuSTAR observations of Mrk 335, and we optimize our fitting procedure to unveil correlations between the Eddington ratio and the spectral parameters. We find that the disc's ionization parameter correlates strongly with the Eddington ratio: the inner disc is more strongly ionized at higher flux. The slope of the correlation is less steep than previously predicted. Furthermore, the cut-off of the power-law spectrum increases in energy with the Eddington ratio, whereas the reflection fraction exhibits a decrease. We interpret this beha...

  8. Accretion Disc Turbulence and the X-Ray Power Spectra of Black Hole High States

    E-Print Network [OSTI]

    Michael A. Nowak; Robert V. Wagoner

    1994-10-06

    The high state of black hole candidates is characterized by a quasi- thermal emission component at $kT \\sim 1$ keV. In addition, this state tends to have very low variability which indicates that it is relatively stable, at least on {\\it short} time scales. Most models of the high state imply that the bulk of the emission comes from an optically thick accretion disc; therefore, this state may be an excellent laboratory for testing our ideas about the physics of accretion discs. In this work we consider the implications of assuming that accretion disc viscosity arises from some form of turbulence. Specifically, we consider the simple case of three dimensional hydrodynamic turbulence. It is found that the coupling of such turbulence to acoustic modes in the disc can alter the disc emission. We calculate the amplitude and frequencies of this modulation, and we express our results in terms of the X-ray power spectral density. We compare our calculations with observations of the black hole candidate GS 1124-683, and show that for certain parameters we can reproduce some of the high frequency power. We then briefly explore mechanisms for producing the low frequency power, and note the difficulty that a single variability mechanism has in reproducing the full range of observed variability. In addition, we outline ways in which future spacecraft missions -- such as USA and XTE -- can further constrain our model, especially at frequencies above $\\sim 10^2$ Hz.

  9. Formation of S0 galaxies through mergers. V. Antitruncated stellar discs resulting from major mergers

    E-Print Network [OSTI]

    Borlaff, Alejandro; Rodríguez-Pérez, Cristina; Querejeta, Miguel; Tapia, Trinidad; Pérez-González, Pablo G; Zamorano, Jaime; Gallego, Jesús; Beckman, John

    2014-01-01

    Lenticular galaxies (S0s) are more likely to host antitruncated (Type-III) stellar discs than galaxies of later Hubble types. Major mergers are popularly considered too violent mechanisms to form these breaks. We have investigated whether major mergers can result into S0-like remnants with realistic antitruncated stellar discs or not. We have analysed 67 relaxed S0 and E/S0 remnants resulting from dissipative N-body simulations of major mergers from the GalMer database. We have simulated realistic R-band surface brightness profiles of the remnants to identify those with antitruncated stellar discs. Their inner and outer discs and the breaks are quantitatively characterized to compare with real data. Nearly 70% of our S0-like remnants are antitruncated, meaning that major mergers that result in S0s have a high probability of producing Type-III stellar discs. Our remnants lie on top of the extrapolations of the observational trends (towards brighter magnitudes and higher break radii) in several photometric diag...

  10. Scattered light images of spiral arms in marginally gravitationally unstable discs with an embedded planet

    E-Print Network [OSTI]

    Pohl, A; Benisty, M; Ataiee, S; Juhasz, A; Dullemond, C P; Van Boekel, R; Henning, T

    2015-01-01

    Scattered light images of transition discs in the near-infrared often show non-axisymmetric structures in the form of wide-open spiral arms in addition to their characteristic low-opacity inner gap region. We study self-gravitating discs and investigate the influence of gravitational instability on the shape and contrast of spiral arms induced by planet-disc interactions. Two-dimensional non-isothermal hydrodynamical simulations including viscous heating and a cooling prescription are combined with three-dimensional dust continuum radiative transfer models for direct comparison to observations. We find that the resulting contrast between the spirals and the surrounding disc in scattered light is by far higher for pressure scale height variations, i.e. thermal perturbations, than for pure surface density variations. Self-gravity effects suppress any vortex modes and tend to reduce the opening angle of planet-induced spirals, making them more tightly wound. If the disc is only marginally gravitationally stable ...

  11. On the migration of two planets in a disc and the formation of mean motion resonances

    E-Print Network [OSTI]

    Migaszewski, Cezary

    2015-01-01

    We study the dynamics of a system of two super-Earths embedded in a protoplanetary disc. Depending on the disc parameters, planets' masses and positions in the disc, the migration of a planet can be inward or outward and the migration of a two-planet system can be convergent or divergent. The convergent migration means that the period ratio P2/P1 decreases in time. In such a case mean motion resonance (MMR) can be formed when the period ratio reaches a resonant value of a first order MMR (p+1)/p, where p is a small integer. When the divergent migration occurs, P2/P1 increases in time and a system initially close to MMR moves away from the resonance. We build a simple model of an irradiated viscous disc and use analytical prescriptions for the planet-disc interactions. We performed 3500 simulations of the migration of two-planet systems with various masses and initial orbits. We found that approximately half of the systems end up as configurations involved in one of the first order MMRs such as 2:1, 3:2, 4:3 a...

  12. We Brake for Mars Hi! My name is Mike Meacham. I'm an engineer here at the Jet Propulsion Laboratory and

    E-Print Network [OSTI]

    Waliser, Duane E.

    We Brake for Mars Hi! My name is Mike Meacham. I'm an engineer here at the Jet Propulsion a really big parachute. To make these large parachutes you have to test them before you go. You need a way've got to test big here on Earth. You got to be a little crazy sometimes if you want to do crazy things

  13. Singular front formation in a model for quasigeostrophic flow Peter Constantin

    E-Print Network [OSTI]

    Tabak, Esteban G.

    Singular front formation in a model for quasigeostrophic flow Peter Constantin Department of Mathematics, University of Chicago, Chicago, Illinois 60637 Andrew J. Majda Department of Mathematics, whether it predicts the formation of sharp fronts associated with boundaries between air masses

  14. Designing and Testing a New Shack-Hartmann High Bandwidth Two-Dimensional Wave front Sensor

    E-Print Network [OSTI]

    Gordeyev, Stanislav

    Designing and Testing a New Shack-Hartmann High Bandwidth Two-Dimensional Wave front Sensor Shaddy Dame, Notre Dame, IN 46656 A novel Shack-Hartmann high bandwidth two-dimensional wave front sensor

  15. Modified Anti-de-Sitter Metric, Light-Front Quantized QCD, and...

    Office of Scientific and Technical Information (OSTI)

    Modified Anti-de-Sitter Metric, Light-Front Quantized QCD, and Conformal Quantum Mechanics Citation Details In-Document Search Title: Modified Anti-de-Sitter Metric, Light-Front...

  16. Magnetic Turbulence and Thermodynamics in the Inner Region of Protoplanetary Discs

    E-Print Network [OSTI]

    Hirose, Shigenobu

    2015-01-01

    Using radiation magnetohydrodynamics simulations with realistic opacities and equation of state, and zero net magnetic flux, we have explored thermodynamics in the inner part of protoplanetary discs where magnetic turbulence is expected. The thermal equilibrium curve consists of the upper, lower, and middle branches. The upper (lower) branch corresponds to hot (cool) and optically very (moderately) thick discs, respectively, while the middle branch is characterized by convective energy transport near the midplane. Convection is also the major energy transport process near the low surface density end of the upper branch. There, convective motion is fast with Mach numbers reaching $\\gtrsim 0.01$, and enhances both magnetic turbulence and cooling, raising the ratio of vertically-integrated shear stress to vertically-integrated pressure by a factor of several. This convectively enhanced ratio seems a robust feature in accretion discs having an ionization transition. We have also examined causes of the S-shaped th...

  17. Evolution of Accretion Discs around a Kerr Black Hole using Extended Magnetohydrodynamics

    E-Print Network [OSTI]

    Francois Foucart; Mani Chandra; Charles F. Gammie; Eliot Quataert

    2015-11-13

    Black holes accreting well below the Eddington rate are believed to have geometrically thick, optically thin, rotationally supported accretion discs in which the Coulomb mean free path is large compared to $GM/c^2$. In such an environment, the disc evolution may differ significantly from ideal magnetohydrodynamic predictions. We present non-ideal global axisymmetric simulations of geometrically thick discs around a rotating black hole. The simulations are carried out using a new code ${\\rm\\it grim}$, which evolves a covariant extended magnetohydrodynamics model derived by treating non-ideal effects as a perturbation of ideal magnetohydrodynamics. Non-ideal effects are modeled through heat conduction along magnetic field lines, and a difference between the pressure parallel and perpendicular to the field lines. The model relies on an effective collisionality in the disc from wave-particle scattering and velocity-space (mirror and firehose) instabilities. We find that the pressure anisotropy grows to match the magnetic pressure, at which point it saturates due to the mirror instability. The pressure anisotropy produces outward angular momentum transport with a magnitude comparable to that of MHD turbulence in the disc, and a significant increase in the temperature in the wall of the jet. We also find that, at least in our axisymmetric simulations, conduction has a small effect on the disc evolution because (1) the heat flux is constrained to be parallel to the field and the field is close to perpendicular to temperature gradients, and (2) the heat flux is choked by an increase in effective collisionality associated with the mirror instability.

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

    E-Print Network [OSTI]

    Chen, .Dake

    winds at sharp oceanic fronts, suggesting a potentially important role played by local airAir-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

  19. Rapid uplift of nonmethane hydrocarbons in a cold front over central Europe

    E-Print Network [OSTI]

    Arnold, Steve

    Rapid uplift of nonmethane hydrocarbons in a cold front over central Europe R. M. Purvis,1 A. C of a cold front, a rapid uplift of reactive carbon from the boundary layer to the mid free troposphere, convection Citation: Purvis, R. M., et al., Rapid uplift of nonmethane hydrocarbons in a cold front over

  20. Wave-front generation of Zernike polynomial modes with a micromachined membrane

    E-Print Network [OSTI]

    Fainman, Yeshaiahu

    Wave-front generation of Zernike polynomial modes with a micromachined membrane deformable mirror the characteristics of a 37-channel micromachined membrane deformable mirror for wave-front generation. We demonstrate wave-front generation of the first 20 Zernike polynomial modes, using an iterative algorithm to adjust

  1. W.C. Heraeus GmbH and its activities regarding large grain Niobium Discs

    SciTech Connect (OSTI)

    Spaniol, Bernd

    2007-08-09

    W.C. Heraeus is one of the leading companies in the field of precious and refractory metals. The refractory metals activities have been started in 1940. W.C. Heraeus is one of the qualified suppliers for high pure Niobium for the use in high-frequency-super-conducting cavities. The latest activities in that field are the development of a stable Electron-Beam-Melting and reliable cutting processes to produce large grain Niobium discs directly cut from the Ingot in an industrial scale. The first cavities out of these discs have been tested and are showing excellent magnetic properties.

  2. Application of object oriented programming techniques in front end computers

    SciTech Connect (OSTI)

    Skelly, J.F. [Brookhaven National Lab., Upton, NY (United States). AGS Dept.

    1997-11-01

    The Standard Model for accelerator control systems describes two levels of computers, often called Console Level Computers (CLCs) and Front End Computers (FECs), joined by a network. The Front End Computer (FEC) environment imposes special demands on software, beyond real time performance and robustness. FEC software must manage a diverse inventory of devices with individualistic timing requirements and hardware interfaces. It must implement network services which export device access to the control system at large, interpreting a uniform network communications protocol into the specific control requirements of the individual devices. Object oriented languages provide programming techniques which neatly address these challenges, and also offer benefits in terms of maintainability and flexibility. Applications are discussed which exhibit the use of inheritance, multiple inheritance and inheritance trees, and polymorphism to address the needs of FEC software.

  3. The Gaia-ESO Survey: a quiescent Milky Way with no significant dark/stellar accreted disc

    E-Print Network [OSTI]

    Ruchti, G R; Feltzing, S; Serenelli, A M; McMillan, P; Lind, K; Bensby, T; Bergemann, M; Asplund, M; Vallenari, A; Flaccomio, E; Pancino, E; Korn, A J; Recio-Blanco, A; Bayo, A; Carraro, G; Costado, M T; Damiani, F; Heiter, U; Hourihane, A; Jofre, P; Kordopatis, G; Lardo, C; de Laverny, P; Monaco, L; Morbidelli, L; Sbordone, L; Worley, C C; Zaggia, S

    2015-01-01

    According to our current cosmological model, galaxies like the Milky Way are expected to experience many mergers over their lifetimes. The most massive of the merging galaxies will be dragged towards the disc-plane, depositing stars and dark matter into an accreted disc structure. In this work, we utilize the chemo-dynamical template developed in Ruchti et al. to hunt for accreted stars. We apply the template to a sample of 4,675 stars in the third internal data release from the Gaia-ESO Spectroscopic Survey. We find a significant component of accreted halo stars, but find no evidence of an accreted disc component. This suggests that the Milky Way has had a rather quiescent merger history since its disc formed some 8-10 billion years ago and therefore possesses no significant dark matter disc.

  4. Light Front Quantization with the Light Cone Gauge

    E-Print Network [OSTI]

    D. G. C. McKeon; Chenguang Zhao

    2015-10-07

    The Dirac procedure for dealing with constraints is applied to the quantization of gauge theories on the light front. The light cone gauge is used in conjunction with the first class constraints that arise and the resulting Dirac brackets are found. These gauge conditions are not used to eliminate degrees of freedom from the action prior to applying the Dirac constraint procedure. This approach is illustrated by considering Yang-Mills theory and the superparticle in a 2 + 1 dimensional target space.

  5. A turnstile mechanism for fronts propagating in fluid flows

    E-Print Network [OSTI]

    John R. Mahoney; Kevin A. Mitchell

    2013-05-22

    We consider the propagation of fronts in a periodically driven flowing medium. It is shown that the progress of fronts in these systems may be mediated by a turnstile mechanism akin to that found in chaotic advection. We first define the modified ("active") turnstile lobes according to the evolution of point sources across a transport boundary. We then show that the lobe boundaries may be constructed from stable and unstable \\emph{burning invariant manifolds}---one-way barriers to front propagation analogous to traditional invariant manifolds for passive advection. Because the burning invariant manifolds (BIMs) are one-dimensional curves in a three-dimensional ($xy\\theta$) phase space, their projection into $xy$-space exhibits several key differences from their advective counterparts: (lobe) areas are not preserved, BIMs may self-intersect, and an intersection between stable and unstable BIMs does not map to another such intersection. These differences must be accommodated in the correct construction of the new turnstile. As an application, we consider a lobe-based treatment protocol for protecting an ocean bay from an invading algae bloom.

  6. The effects of a magnetic field on planetary migration in laminar and turbulent discs

    E-Print Network [OSTI]

    Comins, M L; Koldoba, A V; Ustyugova, G V; Lovelace, R V E

    2015-01-01

    We investigate the migration of low-mass planets ($5 M_{\\oplus}$ and $20 M_{\\oplus}$) in accretion discs threaded with a magnetic field using 2D MHD code in polar coordinates. We observed that, in the case of a strong azimuthal magnetic field where the plasma parameter is $\\beta\\sim 1-2$, density waves at the magnetic resonances exert a positive torque on the planet and may slow down or reverse its migration. However, when the magnetic field is weaker (i.e., the plasma parameter $\\beta$ is relatively large), then non-axisymmetric density waves excited by the planet lead to growth of the radial component of the field and, subsequently, to development of the magneto-rotational instability, such that the disc becomes turbulent. Migration in a turbulent disc is stochastic, and the migration direction may change as such. To understand migration in a turbulent disc, both the interaction between a planet and individual turbulent cells, as well as the interaction between a planet and ordered density waves, have been ...

  7. Pressure-driven outflow and magneto-centrifugal wind from a dynamo active disc

    E-Print Network [OSTI]

    Dobler, Wolfgang

    Pressure-driven outflow and magneto-centrifugal wind from a dynamo active disc Wolfgang Dobler1 outflow near the rotation axis and a centrifugally driven uncollimated wind in the outer parts. The jet be launched and collimated by centrifugal and magnetic forces. This idea has been further developed

  8. Boundary uniqueness theorems for functions whose integrals over hyperbolic discs vanish

    SciTech Connect (OSTI)

    Ochakovskaya, Oksana A

    2013-02-28

    Sharp conditions are found describing the admissible rate of decrease of a nontrivial function whose integrals over all hyperbolic discs with fixed radius vanish. For the first time, the boundary behaviour of the function is investigated in a neighbourhood of a single point on the boundary of the domain of definition. Bibliography: 17 titles.

  9. Copyright 1996, American Institute of Aeronautics and Astronautics, Inc. AIAA Meeting Papers on Disc, January 1996

    E-Print Network [OSTI]

    Texas at Arlington, University of

    as a deflagration. The pulse detonation wave engine utilizes combustion at supersonic velocities by detonation waves on Disc, January 1996 A9618308, AIAA Paper 96-0346 Experimental investigation of a multi-cycle pulsed at the University of Texas at Arlington has been modified to run in a multi-cycle mode as a Pulse Detonation Engine

  10. 2D-Zernike polynomials and coherent state quantization of the unit disc

    E-Print Network [OSTI]

    K. Thirulogasanthar; Nasser Saad; G. Honnouvo

    2015-01-07

    Using the orthonormality of the 2D-Zernike polynomials, reproducing kernels, reproducing kernel Hilbert spaces, and ensuring coherent states attained. With the aid of the so-obtained coherent states, the complex unit disc is quantized. Associated upper symbols, lower symbols and related generalized Berezin transforms also obtained. A number of necessary summation formulas for the 2D-Zernike polynomials proved.

  11. DiSC: Benchmarking Secure Chip DBMS Nicolas Anciaux, Luc Bouganim, Philippe Pucheral, and Patrick Valduriez

    E-Print Network [OSTI]

    DiSC: Benchmarking Secure Chip DBMS Nicolas Anciaux, Luc Bouganim, Philippe Pucheral, and Patrick irrelevant. The main problem faced by secure chip DBMS designers is to be able to assess various design choices and trade-offs for different applications. Our solution is to use a benchmark for secure chip DBMS

  12. Searching for signatures of planet formation in stars with circumstellar debris discs

    E-Print Network [OSTI]

    Maldonado, J; Villaver, E; Montesinos, B; Mora, A

    2015-01-01

    (Abridged) Tentative correlations between the presence of dusty debris discs and low-mass planets have been presented. In parallel, detailed chemical abundance studies have reported different trends between samples of planet and non-planet hosts. We determine in a homogeneous way the metallicity, and abundances of a sample of 251 stars including stars with known debris discs, with debris discs and planets, and only with planets. Stars with debris discs and planets have the same [Fe/H] behaviour as stars hosting planets, and they also show a similar -Tc trend. Different behaviour in the -Tc trend is found between the samples of stars without planets and the samples of planet hosts. In particular, when considering only refractory elements, negative slopes are shown in cool giant planet hosts, whilst positive ones are shown in stars hosting low-mass planets. Stars hosting exclusively close-in giant planets show higher metallicities and positive -Tc slope. A search for correlations between the -Tc slopes and the ...

  13. Resonant Trapping in the Galactic Disc and Halo and its Relation with Moving Groups

    E-Print Network [OSTI]

    Moreno, Edmundo; Schuster, William

    2015-01-01

    With the use of a detailed Milky Way nonaxisymmetric potential, observationally and dynamically constrained, the e?ects of the bar and the spiral arms in the Galaxy are studied in the disc and in the stellar halo. Especially the trapping of stars in the disc and Galactic halo by resonances on the Galactic plane, induced by the Galactic bar, has been analysed in detail. To this purpose, a new method is presented to delineate the trapping regions using empirical diagrams of some orbital properties obtained in the Galactic potential. In these diagrams we plot in the inertial Galactic frame a characteristic orbital energy versus a characteristic orbital angular momentum, or versus the orbital Jacobi constant in the reference frame of the bar, when this is the only nonaxisymmetric component in the Galactic potential. With these diagrams some trapping regions are obtained in the disc and halo using a sample of disc stars and halo stars in the solar neighbourhood. We compute several families of periodic orbits on th...

  14. Gas dynamics in tidal dwarf galaxies: disc formation at z=0

    E-Print Network [OSTI]

    Lelli, F; Brinks, E; Bournaud, F; McGaugh, S S; Lisenfeld, U; Weilbacher, P M; Boquien, M; Revaz, Y; Braine, J; Koribalski, B S; Belles, P -E

    2015-01-01

    Tidal dwarf galaxies (TDGs) are recycled objects that form within the collisional debris of interacting/merging galaxies. They are expected to be devoid of non-baryonic dark matter, since they can form only from dissipative material ejected from the discs of the progenitor galaxies. We investigate the gas dynamics in a sample of six bona-fide TDGs around three interacting and post-interacting systems: NGC 4694, NGC 5291, and NGC 7252 ("Atoms for Peace"). For NGC 4694 and NGC 5291 we analyse existing HI data from the Very Large Array (VLA), while for NGC 7252 we present new HI observations from the Jansky VLA together with long-slit and integral-field optical spectroscopy. For all six TDGs, the HI emission can be described by rotating disc models. These HI discs, however, have undergone less than a full rotation since the time of the interaction/merger event, raising the question of whether they are in dynamical equilibrium. Assuming that these discs are in equilibrium, the inferred dynamical masses are consis...

  15. MSC response to pH levels found in degenerating intervertebral discs

    SciTech Connect (OSTI)

    Wuertz, Karin [School of Engineering, University of Vermont, Burlington, Vermont (United States); Spine Research Group, Competence Center for Applied Biotechnology and Molecular Medicine, University of Zurich, Zurich (Switzerland)], E-mail: wuertz@cabmm.uzh.ch; Godburn, Karolyn; Iatridis, James C. [School of Engineering, University of Vermont, Burlington, Vermont (United States)

    2009-02-20

    Painful degenerative disc disease is a major health problem and for successful tissue regeneration, MSCs must endure and thrive in a harsh disc microenvironment that includes matrix acidity as a critical factor. MSCs were isolated from bone marrow of Sprague-Dawley rats from two different age groups (<1 month, n = 6 and 4-5 months, n = 6) and cultured under four different pH conditions representative of the healthy, mildly or severely degenerated intervertebral disc (pH 7.4, 7.1, 6.8, and 6.5) for 5 days. Acidity caused an inhibition of aggrecan, collagen-1, and TIMP-3 expression, as well as a decrease in proliferation and viability and was associated with a change in cell morphology. Ageing had generally minor effects but young MSCs maintained greater mRNA expression levels. As acidic pH levels are typical of increasingly degenerated discs, our findings demonstrate the importance of early interventions and predifferentiation when planning to use MSCs for reparative treatments.

  16. Anisotropic radiation from accretion disc-coronae in active galactic nuclei

    E-Print Network [OSTI]

    Xu, Ya-Di

    2015-01-01

    In the unification scheme of active galactic nuclei (AGN), Seyfert 1s and Seyfert 2s are intrinsically same, but they are viewed at different angles. However, the Fe K\\alpha emission line luminosity of Seyfert 1s was found in average to be about twice of that of Seyfert 2s at given X-ray continuum luminosity in the previous work (Ricci et al. 2014). We construct an accretion disc-corona model, in which a fraction of energy dissipated in the disc is extracted to heat the corona above the disc. The radiation transfer equation containing Compton scattering processes is an integro-differential equation, which is solved numerically for the corona with a parallel plane geometry. We find that the specific intensity of X-ray radiation from the corona changes little with the viewing angle \\theta when \\theta is small (nearly face-on), and it is sensitive to \\theta if the viewing angle is large (\\theta> 40 degrees). The radiation from the cold disc, mostly in infrared/optical/UV bands, is almost proportional to cos\\thet...

  17. Magnetic field structure and torque in accretion discs around millisecond pulsars

    E-Print Network [OSTI]

    Naso, L; Miller, J C

    2013-01-01

    Millisecond pulsars are rather weakly-magnetized neutron stars which are thought to have been spun up by disc accretion, with magnetic linkage between the star and the disc playing a key role. Their spin history depends sensitively on details of the magnetic field structure, but idealized models from the 1980s and 1990s are still commonly used for calculating the magnetic field components. This paper is the third in a series presenting results from a step-by-step analysis which we are making of the problem, starting with very simple models and then progressively including additional features one at a time, with the aim of gaining new insights into the mechanisms involved. In our first two papers, the magnetic field structure in the disc was calculated for a standard Shakura and Sunyaev model, by solving the magnetic induction equation numerically in the stationary limit within the kinematic approximation; here we consider a more general velocity field in the disc, including backflow. We find that the profiles...

  18. Effects of scattering and dust grain size on the temperature structure of protoplanetary discs: A three-layer approach

    E-Print Network [OSTI]

    Akio K. Inoue; Akinori Oka; Taishi Nakamoto

    2008-12-03

    The temperature in the optically thick interior of protoplanetary discs is essential for the interpretation of millimeter observations of the discs, for the vertical structure of the discs, for models of the disc evolution and the planet formation, and for the chemistry in the discs. Since large icy grains have a large albedo even in the infrared, the effect of scattering of the diffuse radiation in the discs on the interior temperature should be examined. We have performed a series of numerical radiation transfer simulations including isotropic scattering by grains with various typical sizes for the diffuse radiation as well as for the incident stellar radiation. We also have developed an analytic model including isotropic scattering to understand the physics concealed in the numerical results. With the analytic model, we have shown that the standard two-layer approach is valid only for grey opacity (i.e. grain size $\\ga10$ \\micron) even without scattering. A three-layer interpretation is required for grain size $\\la10$ \\micron. When the grain size is 0.1--10 \\micron, the numerical simulations show that isotropic scattering reduces the temperature of the disc interior. This reduction is nicely explained by the analytic three-layer model as a result of the energy loss by scatterings of the incident stellar radiation and of the warm diffuse radiation in the disc atmosphere. For grain size $\\ga10$ \\micron (i.e. grey scattering), the numerical simulations show that isotropic scattering does not affect the interior temperature. This is nicely explained by the analytic two-layer model; the energy loss by scattering in the disc atmosphere is exactly offset by the "green-house effect" due to scattering of the cold diffuse radiation in the interior.

  19. Phase-Front Solutions and Instabilities in Forced Oscillations Christian Elphick,1 Aric Hagberg,2 and Ehud Meron3

    E-Print Network [OSTI]

    Hagberg, Aric

    ], the ferrocyanide-iodate-sulfite reaction [15, 16], and catalytic surface reactions [17]. Stationary -fronts exist

  20. Energy Loss at Propagating Jamming Fronts in Granular Gas Clusters

    E-Print Network [OSTI]

    Justin C. Burton; Peter Y. Lu; Sidney R. Nagel

    2013-10-15

    We explore the initial moments of impact between two dense granular clusters in a two-dimensional geometry. The particles are composed of solid CO$_{2}$ and are levitated on a hot surface. Upon collision, the propagation of a dynamic "jamming front" produces a distinct regime for energy dissipation in a granular gas in which the translational kinetic energy decreases by over 90%. Experiments and associated simulations show that the initial loss of kinetic energy obeys a power law in time, $\\Delta E=-Kt^{3/2}$, a form that can be predicted from kinetic arguments.

  1. APPLICATION OF OBJECT ORIENTED PROGRAMMING TECHNIQUES IN FRONT END COMPUTERS.

    SciTech Connect (OSTI)

    SKELLY,J.F.

    1997-11-03

    The Front End Computer (FEC) environment imposes special demands on software, beyond real time performance and robustness. FEC software must manage a diverse inventory of devices with individualistic timing requirements and hardware interfaces. It must implement network services which export device access to the control system at large, interpreting a uniform network communications protocol into the specific control requirements of the individual devices. Object oriented languages provide programming techniques which neatly address these challenges, and also offer benefits in terms of maintainability and flexibility. Applications are discussed which exhibit the use of inheritance, multiple inheritance and inheritance trees, and polymorphism to address the needs of FEC software.

  2. Front-end utility rate updates | OpenEI Community

    Open Energy Info (EERE)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page on Google Bookmark EERE: Alternative Fuels Data Center Home Page on QA:QA J-E-1 SECTION J APPENDIX E LISTStar2-0057-EA Jump to:ofEnia SpAFlex FuelsEnergyInc| Open EnergyFront-end utility

  3. Mn abundances in the stars of the Galactic disc with metallicities -1.0 < [Fe/H] < 0.3

    E-Print Network [OSTI]

    Mishenina, T; Pignatari, M; Thielemann, F -K; Korotin, S A

    2015-01-01

    In this work we present and discuss the observations of the Mn abundances for 247 FGK dwarfs, located in the Galactic disc with metallicity -1supernovae. We confirm the basel...

  4. AN EMPIRICAL FORMULA FOR THE DISTRIBUTION FUNCTION OF A THIN EXPONENTIAL DISC

    SciTech Connect (OSTI)

    Sharma, Sanjib; Bland-Hawthorn, Joss [Sydney Institute for Astronomy, School of Physics, University of Sydney, NSW 2006 (Australia)

    2013-08-20

    An empirical formula for a Shu distribution function that reproduces a thin disc with exponential surface density to good accuracy is presented. The formula has two free parameters that specify the functional form of the velocity dispersion. Conventionally, this requires the use of an iterative algorithm to produce the correct solution, which is computationally taxing for applications like Markov Chain Monte Carlo model fitting. The formula has been shown to work for flat, rising, and falling rotation curves. Application of this methodology to one of the Dehnen distribution functions is also shown. Finally, an extension of this formula to reproduce velocity dispersion profiles that are an exponential function of radius is also presented. Our empirical formula should greatly aid the efficient comparison of disc models with large stellar surveys or N-body simulations.

  5. Method and system for assigning a confidence metric for automated determination of optic disc location

    DOE Patents [OSTI]

    Karnowski, Thomas P. (Knoxville, TN); Tobin, Jr., Kenneth W. (Harriman, TN); Muthusamy Govindasamy, Vijaya Priya (Knoxville, TN); Chaum, Edward (Memphis, TN)

    2012-07-10

    A method for assigning a confidence metric for automated determination of optic disc location that includes analyzing a retinal image and determining at least two sets of coordinates locating an optic disc in the retinal image. The sets of coordinates can be determined using first and second image analysis techniques that are different from one another. An accuracy parameter can be calculated and compared to a primary risk cut-off value. A high confidence level can be assigned to the retinal image if the accuracy parameter is less than the primary risk cut-off value and a low confidence level can be assigned to the retinal image if the accuracy parameter is greater than the primary risk cut-off value. The primary risk cut-off value being selected to represent an acceptable risk of misdiagnosis of a disease having retinal manifestations by the automated technique.

  6. Circumstellar discs in X/gamma-ray binaries: first results from the Echelle spectrograph

    E-Print Network [OSTI]

    Zamanov, R; Martí, J

    2015-01-01

    Here we report our first spectral observations of Be/X-ray and gamma-ray binaries obtained with the new Echelle spectrograph of the National Astronomical Observatory Rozhen. For four objects (LSI+61303, gamma Cas, MWC 148, 4U 2206+54), we report the parameters and estimate the sizes of their circumstellar discs using different emission lines (H-alpha, H-beta, H-gamma, HeI and FeII). For MWC 148, we find that the compact object goes deeply through the disc. The flank inflections of H-alpha can be connected with inner ring formed at the periastron passage or radiation transfer effects. We point out an intriguing similarity between the optical emission lines of the $\\gamma$-ray binary MWC 148 and the well known Be star $\\gamma$ Cas.

  7. A counter-rotating tilted gas disc in the peanut galaxy NGC~128

    E-Print Network [OSTI]

    Eric Emsellem; Robin Arsenault

    1997-01-15

    We have obtained $V$, $R_c$, $I_c$ HRCAM images and TIGER spectrography of the central region of the peanut galaxy NGC~128. The colour images reveal the presence of a red disc tilted by about 26 degres with respect to the major-axis of the galaxy. This tilted disc is made of dust and gas, as revealed by the 2D TIGER map of the ionized gas distribution. The TIGER stellar and gas velocity fields show that the angular momentum vectors of the stellar and gaseous components are reversed. We therefore suggest that the gas orbits belong to the so-called anomalous family, which is evidence for a tumbling triaxial potential (a bar) associated with the peanut morphology. The bar formation has very probably been triggered through the interaction with its nearby companion NGC~127, from which the dissipative component is being accreted along retrograde orbits.

  8. Reprocessing of X-rays in the outer accretion disc of the black hole binary XTE J1817--330

    E-Print Network [OSTI]

    Marek Gierlinski; Chris Done; Kim Page

    2008-11-06

    We build a simple model of the optical/UV emission from irradiation of the outer disc by the inner disc and coronal emission in black hole binaries. We apply this to the broadband Swift data from the outburst of the black hole binary XTE J1817--330 to confirm previous results that the optical/UV emission in the soft state is consistent with a reprocessing a constant fraction of the bolometric X-ray luminosity. However, this is very surprising as the disc temperature drops by more than a factor 3 in the soft state, which should produce a marked change in the reprocessing efficiency. The easiest way to match the observed constant reprocessed fraction is for the disc skin to be highly ionized (as suggested 30 years ago by van Paradijs), so that the bulk of the disc flux is reflected and only the hardest X-rays heat the disc. The constant reprocessed fraction also favours direct illumination of the disc over a scattering origin as the optical depth/solid angle of any scattering material (wind/corona) over the disc should decrease as the source luminosity declines. By contrast, the reprocessed fraction increases very significantly (by a factor ~6) as the source enters the hard state. This dramatic change is not evident from X-ray/UV flux correlations as it is masked by bandpass effects. However, it does not necessarily signal a change in emission e.g. the emergence of the jet dominating the optical/UV flux as the reflection albedo must change with the dramatic change in spectral shape.

  9. Nuclear Physics on the Light Front - a new old way to do an old new problem

    E-Print Network [OSTI]

    Gerald A. Miller

    1999-08-10

    A brief introduction to light front techniques is presented. This is followed by a review of recent attempts to perform realistic, relativistic nuclear physics with those techniques.

  10. Higher-order differencing for phase-front propagation in geothermal systems

    E-Print Network [OSTI]

    Oldenburg, Curtis; Pruess, Karsten

    1998-01-01

    FRONT PROPAGATION IN GEOTHERMAL SYSTEMS Curtis M. Oldenburgreinjection in geothermal systems. The numerical simulationcases that can arise in geothermal systems where saturation

  11. Women of Color and Minorities on the Home front during World War II

    E-Print Network [OSTI]

    Sanders-Pinto, Camille

    2015-01-01

    and Minorities on the Home front during World War II ByCamille Sanders-Pinto During World War II minority women

  12. Time series analysis of Adaptive Optics wave-front sensor telemetry...

    Office of Scientific and Technical Information (OSTI)

    for each subaperture are available. The primary problem is performance comparison of alternative wave-front sensing algorithms. Using direct comparison of data in open loop and...

  13. AMBER/VLTI high spectral resolution observations of the Br$\\gamma$ emitting region in HD 98922. A compact disc wind launched from the inner disc region

    E-Print Network [OSTI]

    Garatti, A Caratti o; Lopez, R Garcia; Kraus, S; Schertl, D; Grinin, V P; Weigelt, G; Hofmann, K -H; Massi, F; Lagarde, S; Vannier, M; Malbet, F

    2015-01-01

    We analyse the main physical parameters and the circumstellar environment of the young Herbig Be star HD 98922. We present AMBER/VLTI high spectral resolution (R =12000) interferometric observations across the Br$\\gamma$ line, accompanied by UVES high-resolution spectroscopy and SINFONI-AO assisted near-infrared integral field spectroscopic data. To interpret our observations, we develop a magneto-centrifugally driven disc-wind model. Our analysis of the UVES spectrum shows that HD 98922 is a young (~5x10^5 yr) Herbig Be star (SpT=B9V), located at a distance of 440(+60-50) pc, with a mass accretion rate of ~9+/-3x10^(-7) M_sun yr^(-1). SINFONI K-band AO-assisted imaging shows a spatially resolved circumstellar disc-like region (~140 AU in diameter) with asymmetric brightness distribution. Our AMBER/VLTI UT observations indicate that the Br$\\gamma$ emitting region (radius ~0.31+/-0.04 AU) is smaller than the continuum emitting region (inner dust radius ~0.7+/-0.2 AU), showing significant non-zero V-shaped diff...

  14. Analytical modeling of a new disc permanent magnet linear synchronous machine for electric vehicles

    SciTech Connect (OSTI)

    Liu, C.T.; Chen, J.W.; Su, K.S.

    1999-09-01

    This paper develops an analytical approach based on a qd0 reference frame model to analyze dynamic and steady state characteristics of disc permanent magnet linear synchronous machines (DPMLSMs). The established compact mathematical model can be more easily employed to analyze the system behavior and to design the controller. Superiority in operational electromagnetic characteristics of the proposed DPMLSM for electric vehicle (EV) applications is verified by both numerical simulations and experimental investigations.

  15. The excitation of spiral density waves through turbulent fluctuations in accretion discs I: WKBJ theory

    E-Print Network [OSTI]

    T. Heinemann; J. C. B. Papaloizou

    2009-04-30

    We study and elucidate the mechanism of spiral density wave excitation in a differentially rotating turbulent flow. We formulate a set of wave equations with sources that are only non-zero in the presence of turbulent fluctuations. We solve these in a shearing box domain using a WKBJ method. It is found that, for a particular azimuthal wave length, the wave excitation occurs through a sequence of regularly spaced swings during which the wave changes from leading to trailing form. This is a generic process that is expected to occur in shearing discs with turbulence. Trailing waves of equal amplitude propagating in opposite directions are produced, both of which produce an outward angular momentum flux that we give expressions for as functions of the disc parameters and azimuthal wave length. By solving the wave amplitude equations numerically we justify the WKBJ approach for a Keplerian rotation law for all parameter regimes of interest. In order to quantify the wave excitation completely the important wave source terms need to be specified. Assuming conditions of weak nonlinearity, these can be identified and are associated with a quantity related to the potential vorticity, being the only survivors in the linear regime. Under the additional assumption that the source has a flat power spectrum at long azimuthal wave lengths, the optimal azimuthal wave length produced is found to be determined solely by the WKBJ response and is estimated to be 2 pi H, with H being the nominal disc scale height.

  16. Photometric scaling relations of antitruncated stellar discs in S0-Scd galaxies

    E-Print Network [OSTI]

    Eliche-Moral, M Carmen; Beckman, John E; Gutierrez, Leonel

    2015-01-01

    It has been recently found that the characteristic photometric parameters of antitruncated discs in S0 galaxies follow tight scaling relations. We investigate if similar scaling relations are satisfied by galaxies of other morphological types. We have analysed the trends in several photometric planes relating the characteristic surface brightness and scalelengths of the breaks and the inner and outer discs of local antitruncated S0-Scd galaxies, using published data and fits performed to the surface brightness profiles of two samples of Type-III galaxies in the R and Spitzer 3.6 microns bands. We have performed linear fits to the correlations followed by different galaxy types in each plane, as well as several statistical tests to determine their significance. We have found that: 1) the antitruncated discs of all galaxy types from Sa to Scd obey tight scaling relations both in R and 3.6 microns, as observed in S0s; 2) the majority of these correlations are significant accounting for the numbers of the availab...

  17. Constraints on a planetary origin for the gap in GM Aurigae's protoplanetary disc

    E-Print Network [OSTI]

    W. K. M. Rice; Kenneth Wood; P. J. Armitage; B. A. Whitney; J. E. Bjorkman

    2003-02-11

    The unusual spectral energy distribution (SED) of the classical T Tauri star GM Aurigae provides evidence for the presence of an inner disc hole extending to several au. Using a combination of hydrodynamical simulations and Monte Carlo radiative transport, we investigate whether the observed SED is consistent with the inner hole being created and maintained by an orbiting planet. We show that an ~ 2 M_Jupiter planet, orbiting at 2.5 au in a disc with mass 0.047 M_sun and radius 300 au, provides a good match both to the SED and to CO observations which constrain the velocity field in the disc. A range of planet masses is allowed by current data, but could in principle be distinguished with further observations between 3 and ~ 20 microns. Future high precision astrometric instruments should also be able to detect the motion of the central star due to an orbiting Jupiter mass planet. We argue that the small number of T Tauri stars with SEDs resembling that of GM Aur is broadly consistent with the expected statistics of embedded migrating planets.

  18. X-ray irradiation in XTE J1817-330 and the inner radius of the truncated disc in the hard state

    E-Print Network [OSTI]

    Marek Gierlinski; Chris Done; Kim Page

    2008-05-07

    The key aspect of the very successful truncated disc model for the low/hard X-ray spectral state in black hole binaries is that the geometrically thin disc recedes back from the last stable orbit at the transition to this state. This has recently been challenged by direct observations of the low/hard state disc from CCD data. We reanalyze the Swift and RXTE campaign covering the 2006 outburst of XTE J1817-330 and show that these data actually strongly support the truncated disc model as the transition spectra unambiguously show that the disc begins to recede as the source leaves the disc dominated soft state. The disc radius inferred for the proper low/hard state is less clear-cut, but we show that the effect of irradiation from the energetically dominant hot plasma leads to an underestimate of the disc radius by a factor of 2-3 in this state. This may also produce the soft excess reported in some hard-state spectra. The inferred radius becomes still larger when the potential difference in stress at the inner boundary, increased colour temperature correction from incomplete thermalization of the irradiation, and loss of observable disc photons from Comptonization in the hot plasma are taken into account. We conclude that the inner disc radius in XTE J1817-330 in the low/hard spectral state is at least 6-8 times that seen in the disc dominated high/soft state, and that recession of the inner disc is the trigger for the soft--hard state transition, as predicted by the truncated disc models.

  19. Nonlocal competition and logistic growth: patterns, defects and fronts

    E-Print Network [OSTI]

    Yosef E. Maruvka; Nadav M. Shnerb

    2005-06-22

    Logistic growth of diffusing reactants on spatial domains with long range competition is studied. The bifurcations cascade involved in the transition from the homogenous state to a spatially modulated stable solution is presented, and a distinction is made between a modulated phase, dominated by single or few wavenumbers, and the spiky phase, where localized colonies are separated by depleted region. The characteristic defects in the periodic structure are presented for each phase, together with the invasion dynamics in case of local initiation. It is shown that the basic length scale that controls the bifurcation is the width of the Fisher front, and that the total population grows as this width decreases. A mix of analytic results and extensive numerical simulations yields a comprehensive examination of the possible phases for logistic growth in the presence of nonlocal competition.

  20. High-Level Information An Approach for Integrating Front-End and Back-End Compilers

    E-Print Network [OSTI]

    Li, Zhiyuan

    High-Level Information ­ An Approach for Integrating Front-End and Back-End Compilers Sangyeun Cho-end and back-end compilers by passing front-end information to the back-end compiler. Importing this information into an existing back- end leverages the state-of-the-art analysis and transforma- tion

  1. GLOBAL OPTIMIZATION OF THE MUON COLLIDER/NEUTRINO FACTORY FRONT END

    E-Print Network [OSTI]

    McDonald, Kirk

    GLOBAL OPTIMIZATION OF THE MUON COLLIDER/NEUTRINO FACTORY FRONT END HISHAM SAYED BROOKHAVEN MEETING 10 September 2013 #12;GLOBALLY OPTIMIZING MUON TARGET & FRONT END 9/10/13 2 in bunches #12;INTRODUCTION & LAYOUT Ã? High performance Optimization Tools on NERSC Ã? Target: Ã?

  2. Are mesoscale eddies in shelf seas formed by baroclinic instability of tidal fronts?

    E-Print Network [OSTI]

    Williams, Ric

    Are mesoscale eddies in shelf seas formed by baroclinic instability of tidal fronts? G. Badin,1 R; accepted 23 July 2009; published 27 October 2009. [1] The formation of eddies along tidal fronts signals are dampened by air-sea interaction and eroded by wind and tidal mixing. High-resolution CTD

  3. SCIPP-04/03 Characterization the Front-End electronics in order to

    E-Print Network [OSTI]

    California at Santa Cruz, University of

    SCIPP-04/03 Characterization the Front-End electronics in order to Calibrate the PTSM Completed by-End electronics of the PTSM, data was collected on the gain of the system. This was done using known quantities a value known as Time Over Threshold (TOT). The TOT is measured by the PTSM Front-End (FE) electronics

  4. Title of Dissertation: NONLINEAR DYNAMICS OF EXTENDED SYSTEMS: CHAOS FRONTS, RARE INTENSE EVENTS,

    E-Print Network [OSTI]

    Anlage, Steven

    ABSTRACT Title of Dissertation: NONLINEAR DYNAMICS OF EXTENDED SYSTEMS: CHAOS FRONTS, RARE INTENSE Edward Ott Department of Physics We investigate the nonlinear dynamics of three extended systems: chaos considered as nodes and actors as links. #12;NONLINEAR DYNAMICS OF EXTENDED SYSTEMS: CHAOS FRONTS, RARE

  5. Historical Fire Regimes in Ponderosa Pine Forests of the Colorado Front Range, and

    E-Print Network [OSTI]

    Historical Fire Regimes in Ponderosa Pine Forests of the Colorado Front Range, and Recommendations scientific understanding of historical fire regimes in the forested landscapes of Colorado's Front Range and the Colorado-Wyoming border. This article focuses on forests in which ponderosa pine is a dominant or co

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

    E-Print Network [OSTI]

    Gohm, Alexander

    in Inn and Wipp Valley Temperature slope profile Doppler wind lidar in Wipp Valley #12;6 of 13 Case study study Wipp Valley: AWS network Pot. Temp. and Wind ­ Hovmoeller diagram Strong and warm foehn in the lower Wipp Valley Western Inn-Valley gust front enters Wipp Valley Cold front propagates southward

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

    E-Print Network [OSTI]

    Schultz, David

    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

  8. A Comprehensive Energy Model and Energy-Quality Evaluation of Wireless Transceiver Front-Ends

    E-Print Network [OSTI]

    Kambhampati, Subbarao

    1 A Comprehensive Energy Model and Energy-Quality Evaluation of Wireless Transceiver Front-Ends Y and a multi-user CDMA based system with respect to RF front end energy consumption and communication quality section of a wireless transceiver consumes more energy than the digital part. For better understanding

  9. APPLICATIONS OF FRONT TRACKING TO THE SIMULATION OF RESIN TRANSFER MOLDING

    E-Print Network [OSTI]

    New York at Stoney Brook, State University of

    APPLICATIONS OF FRONT TRACKING TO THE SIMULATION OF RESIN TRANSFER MOLDING Yu Song 1 2 Department: Computers & Mathematics with applications Abstract Resin Transfer Molding, as a method for the manufacture enhance product quality. Key words. resin transfer molding, composite materials, front tracking

  10. Finding the Salt Front: Page 1 Saltwater fish like flounder move up

    E-Print Network [OSTI]

    Lance, Veronica P.

    upriver, which is 20-50 mg/L. The salt front's location is given in Hudson River Miles (abbreviated HRM). Hudson River Miles start at Manhattan's southern tip. This spot, called the Battery, is HRM 0. Going north, Yonkers is at HRM 18, Poughkeepsie at HRM 75. The salt front moves with the tides, weather

  11. Persistence of zero velocity fronts in reaction diffusion systems Lorenz Kramer

    E-Print Network [OSTI]

    Gottwald, Georg A.

    Persistence of zero velocity fronts in reaction diffusion systems Lorenz Kramer Physikalisches; accepted for publication 15 June 2000 Steady, nonpropagating, fronts in reaction diffusion systems usually velocity may become zero only at isolated values where the Maxwell condition is satisfied, for potential

  12. FRONT SPEEDS IN THE VANISHING DIFFUSION LIMIT FOR REACTION-DIFFUSION-CONVECTION EQUATIONS

    E-Print Network [OSTI]

    Mascia, Corrado

    velocity. This convergence also yields a reaction- independent sufficient condition for the minimalFRONT SPEEDS IN THE VANISHING DIFFUSION LIMIT FOR REACTION-DIFFUSION-CONVECTION EQUATIONS E.C.M. CROOKS AND C. MASCIA Abstract. Travelling fronts for scalar balance laws with monostable reaction

  13. Three universality classes for reaction fronts in disordered flows Severine Atis,1

    E-Print Network [OSTI]

    Wiese, Kay Jörg

    flow, the chemical reaction produces traveling waves with velocity V0 inside the medium. An additionalThree universality classes for reaction fronts in disordered flows S´everine Atis,1 Awadhesh Kumar-sustained reaction fronts in a disordered medium subject to an external flow display self-affine roughening, pinning

  14. Wave Front Interaction Model of Stabilized Propagating Wave Segments Vladimir S. Zykov1

    E-Print Network [OSTI]

    Showalter, Kenneth

    Wave Front Interaction Model of Stabilized Propagating Wave Segments Vladimir S. Zykov1 and Kenneth; published 14 February 2005) A wave front interaction model is developed to describe the relationship between excitability and the size and shape of stabilized wave segments in a broad class of weakly excitable media

  15. Observed low frequency variability of the Brazil Current front Gustavo Jorge Goni,1

    E-Print Network [OSTI]

    of the Brazil Current front. Trends of eddy kinetic energy, sea height anomaly, sea surface temperature and windObserved low frequency variability of the Brazil Current front Gustavo Jorge Goni,1 Francis Bringas; published 29 October 2011. [1] The Brazil Current is a weak western boundary current, the southwest

  16. PHYSICAL REVIEW E 87, 012901 (2013) Pinning-depinning transition of fronts between standing waves

    E-Print Network [OSTI]

    Gavilan, Marcel G. Clerc

    2013-01-01

    PHYSICAL REVIEW E 87, 012901 (2013) Pinning-depinning transition of fronts between standing waves behaviors of fronts connecting standing waves, such as the locking phenomenon, pinning-depinning transitions between standing waves. In the driven pendulum chain, using a Galerkin expansion we characterize

  17. MESOSCALE ANALYSIS OF A CAROLINA COASTAL FRONT SETHU RAMAN, NEERAJA C. REDDY and DEVDUTTA S. NIYOGI

    E-Print Network [OSTI]

    Niyogi, Dev

    MESOSCALE ANALYSIS OF A CAROLINA COASTAL FRONT SETHU RAMAN, NEERAJA C. REDDY and DEVDUTTA S. NIYOGI the shore. Key words: GALE, Coastal front, Atmospheric boundary layer, Gulf Stream, Mesoscale analysis turbulent heat fluxes. These strong gradients in heat fluxes enhance mesoscale circulation

  18. Coarsening of precipitation patterns in a moving reaction-diffusion front A. Volford,1

    E-Print Network [OSTI]

    Rácz, Zoltán

    Coarsening of precipitation patterns in a moving reaction-diffusion front A. Volford,1 I. Lagzi,2 November 2009 Precipitation patterns emerging in a two-dimensional moving front are investigated on the example of NaOH diffusing into a gel containing AlCl3. The time evolution of the precipitate Al OH 3 can

  19. PHYSICAL REVIEW E 88, 022141 (2013) Helices in the wake of precipitation fronts

    E-Print Network [OSTI]

    Rácz, Zoltán

    2013-01-01

    PHYSICAL REVIEW E 88, 022141 (2013) Helices in the wake of precipitation fronts Shibi Thomas,1 of the emergence of helices in the wake of precipitation fronts is presented. The precipitation dynamics studies [7,8] in which helical precipitation patterns were observed in the wake of moving reaction

  20. Effect of Initial Disturbance on The Detonation Front Structure of a Narrow Duct

    E-Print Network [OSTI]

    Dou, Hua-Shu

    2010-01-01

    The effect of an initial disturbance on the detonation front structure in a narrow duct is studied by three-dimensional numerical simulation. The numerical method used includes a high resolution fifth-order weighted essentially non-oscillatory scheme for spatial discretization, coupled with a third order total variation diminishing Runge-Kutta time stepping method. Two types of disturbances are used for the initial perturbation. One is a random disturbance which is imposed on the whole area of the detonation front, and the other is a symmetrical disturbance imposed within a band along the diagonal direction on the front. The results show that the two types of disturbances lead to different processes. For the random disturbance, the detonation front evolves into a stable spinning detonation. For the symmetrical diagonal disturbance, the detonation front displays a diagonal pattern at an early stage, but this pattern is unstable. It breaks down after a short while and it finally evolves into a spinning detonati...

  1. The AdS/CFT Correspondence and Light-Front QCD

    E-Print Network [OSTI]

    Stanley J. Brodsky; Guy F. de Teramond

    2008-10-10

    We identify an invariant light-front coordinate $\\zeta$ which allows the separation of 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 Schrodinger equation for QCD which determines the eigenspectrum and the light-front wavefunctions of hadrons for general spin and orbital angular momentum. This frame-independent light-front wave equation is equivalent to the equations of motion which describe the propagation of spin-$J$ modes on anti-de Sitter (AdS) space. Light-front holography is a remarkable feature of AdS/CFT: it 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. In principle, the model can be systematically improved by diagonalizing the full QCD light-front Hamiltonian on the AdS/QCD basis. Quark and gluon hadronization can be computed at the amplitude level by convoluting the off-shell $T$ matrix calculated from the QCD light-front Hamiltonian with the hadronic light-front wavefunctions. We also note the distinction between static observables such as the probability distributions computed from the square of the light-front wavefunctions versus dynamical observables such as the structure functions and the leading-twist single-spin asymmetries measured in deep inelastic scattering which include the effects of initial and final-state interactions.

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

    E-Print Network [OSTI]

    Powell, Johnna, 1980-

    2009-01-01

    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 ...

  3. Equatorial scattering and the structure of the broad-line region in Seyfert nuclei: evidence for a rotating disc

    E-Print Network [OSTI]

    J. E. Smith; A. Robinson; S. Young; D. J. Axon; Elizabeth A. Corbett

    2005-01-28

    We present detailed scattering models confirming that distinctive variations in polarization across the broad Halpha line, which are observed in a significant fraction of Seyfert 1 galaxies, can be understood in terms of a rotating line-emitting disc surrounded by a co-planar scattering region (the equatorial scattering region). The predicted polarization properties are: averaged over wavelength, the position angle of polarization is aligned with the projected disc rotation axis and hence also with the radio source axis; (ii) the polarization PA rotates across the line profile, reaching equal but opposite (relative to the continuum PA) rotations in the blue and red wings; (iii) the degree of polarization peaks in the line wings and passes through a minimum in the line core. We identify 11 objects which exhibit these features to different degrees. In order to reproduce the large amplitude PA rotations observed in some cases, the scattering region must closely surround the emission disc and the latter must itself be a relatively narrow annulus -- presumably the Halpha-emitting zone of a larger accretion disc. Asymmetries in the polarization spectra may be attributable to several possible causes, including bulk radial infall in the equatorial scattering region, or contamination by polar scattered light. The broad Halpha lines do not, in general, exhibit double-peaked profiles, suggesting that a second Halpha-emitting component of the broad-line region is present, in addition to the disc.

  4. The Gaia-ESO Survey: New constraints on the Galactic disc velocity dispersion and its chemical dependencies

    E-Print Network [OSTI]

    Guiglion, G; de Laverny, P; Kordopatis, G; Hill, V; Mikolaitis, Š; Minchev, I; Chiappini, C; Wyse, R F G; Gilmore, G; Randich, S; Feltzing, S; Bensby, T; Flaccomio, E; Koposov, S E; Pancino, E; Bayo, A; Costado, M T; Franciosini, E; Hourihane, A; Jofré, P; Lardo, C; Lewis, J; Lind, K; Magrini, L; Morbidelli, L; Sacco, G G; Ruchti, G; Worley, C C; Zaggia, S

    2015-01-01

    Understanding the history and the evolution of the Milky Way disc is one of the main goals of modern astrophysics. We study the velocity dispersion behaviour of Galactic disc stars as a function of the [Mg/Fe] ratio, which can be used as a proxy of relative age. This key relation is essential to constrain the formation mechanisms of the disc stellar populations as well as the cooling processes. We used the recommended parameters and chemical abundances of 7800 FGK Milky Way field stars from the second internal data release of the Gaia-ESO Survey. These stars were observed with the GIRAFFE spectrograph, and cover a large spatial volume (6+0.2dex. First, the velocity dispersion increases with [Mg/Fe] at all [Fe/H] ratios for the thin-disc stars, and then it decreases for the thick-disc at the highest [Mg/Fe] abundances. Similar trends are observed within the errors for the azimuthal velocity dispersion, while a continuous increase with [Mg/Fe] is observed for the vertical velocity dispersion. The velocity dispe...

  5. Inhibition of slug front corrosion in multiphase flow conditions

    SciTech Connect (OSTI)

    Chen, H.J.; Jepson, W.P.

    1998-12-31

    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.

  6. Double parton correlations in Light-Front constituent quark model

    E-Print Network [OSTI]

    Matteo Rinaldi; Sergio Scopetta; Marco Traini; Vicente Vento

    2014-12-09

    Double parton distribution functions (dPDF) represent a tool to explore the 3D proton structure. They can be measured in high energy proton-proton and proton nucleus collisions and encode information on how partons inside a proton are correlated among each other. dPFDs are studied here in the valence quark region, by means of a constituent quark model, where two particle correlations are present without any additional prescription. This framework allows to understand the dynamical origin of the correlations and to clarify which, among the features of the results, are model independent. Use will be made of a relativistic light-front scheme, able to overcome some drawbacks of the previous calculation. Transverse momentum correlations, due to the exact treatment of the boosts, are predicted and analyzed. The role of spin correlations is also shown. Due to the covariance of the approach, some symmetries of the dPDFs are seen unambigously. For the valence sector, the study of the QCD evolution of the model results, which can be performed safely thanks to the property of good support, has been also completed.

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

    E-Print Network [OSTI]

    Stanley J. Brodsky; Guy F. de Teramond

    2009-09-22

    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 Schr\\"odinger 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.

  8. Tidal front affects the size of prey used by a top marine predator, the short-tailed shearwater (Puffinus tenuirostris)

    E-Print Network [OSTI]

    Tidal front affects the size of prey used by a top marine predator, the short-tailed shearwater densities of small euphausiids were associated with a tidal front on the north side of Akutan Pass. At most sites elsewhere in the Bering Sea, away from tidal fronts, shearwaters selected larger (14.2­20.1 mm

  9. Abundance gradients in low surface brightness spirals: clues on the origin of common gradients in galactic discs

    E-Print Network [OSTI]

    Bresolin, Fabio

    2015-01-01

    We acquired spectra of 141 HII regions in ten late-type low surface brightness galaxies (LSBGs). The analysis of the chemical abundances obtained from the nebular emission lines shows that metallicity gradients are a common feature of LSBGs, contrary to previous claims concerning the absence of such gradients in this class of galaxies. The average slope, when expressed in units of the isophotal radius, is found to be significantly shallower in comparison to galaxies of high surface brightness. This result can be attributed to the reduced surface brightness range measured across their discs, when combined with a universal surface mass density-metallicity relation. With a similar argument we explain the common abundance gradient observed in high surface brightness galaxy (HSBG) discs and its approximate dispersion. This conclusion is reinforced by our result that LSBGs share the same common abundance gradient with HSBGs, when the slope is expressed in terms of the exponential disc scale length.

  10. Travelling fronts of the CO oxidation on Pd(111) with coverage-dependent diffusion

    SciTech Connect (OSTI)

    Cisternas, Jaime, E-mail: jecisternas@miuandes.cl [Facultad de Ingeniería y Ciencias Aplicadas, Universidad de los Andes, Monseñor Alvaro del Portillo 12455, Las Condes, Santiago (Chile); Karpitschka, Stefan [Physics of Fluids, University of Twente, Drienerlolaan 5, 7522 NB Enschede (Netherlands); Wehner, Stefan [Institut für Integrierte Naturwissenschaften - Physik, Universität Koblenz-Landau, 56070 Koblenz (Germany)

    2014-10-28

    In this work, we study a surface reaction on Pd(111) crystals under ultra-high-vacuum conditions that can be modeled by two coupled reaction-diffusion equations. In the bistable regime, the reaction exhibits travelling fronts that can be observed experimentally using photo electron emission microscopy. The spatial profile of the fronts reveals a coverage-dependent diffusivity for one of the species. We propose a method to solve the nonlinear eigenvalue problem and compute the direction and the speed of the fronts based on a geometrical construction in phase-space. This method successfully captures the dependence of the speed on control parameters and diffusivities.

  11. A new approach to front-­?end electronics interfacing in the ATLAS experiment

    E-Print Network [OSTI]

    Borga, Andrea; The ATLAS collaboration; Lanni, Francesco; Lehmann Miotto, Giovanna; Levinson, Lorne; Narevicius, Julia; Roich, Alexander; Schreuder, Frans Philip; Schumacher, J\\"orn; Vandelli, Wainer; Vermeulen, Jos; Ryu, Soo; Zhang, Jinlong; Anderson, John Thomas; Boterenbrood, Hendrik; Chen, Kai; Chen, Hucheng; Drake, Gary; Donszelmann, Mark; Francis, David

    2015-01-01

    For new detector and trigger systems to be installed in the ATLAS experiment after LHC Run 2 a new approach will be followed for front-end electronics interfacing. The FELIX (Front-End Link eXchange) system will interface to links connecting to front-end detector and trigger electronics instead of the RODs (ReadOut Drivers) currently used. FELIX will function as a gateway to a commodity switched network built using standard technology (either Ethernet or Infiniband). In the paper the new approach will be described and results of the demonstrator program currently in progress will be presented.

  12. The Spatially-Resolved Star Formation History of the M31 Outer Disc

    E-Print Network [OSTI]

    Bernard, Edouard J; Chapman, Scott C; Ibata, Rodrigo A; Irwin, Mike J; Lewis, Geraint F; McConnachie, Alan W

    2015-01-01

    We present deep Hubble Space Telescope Advanced Camera for Surveys observations of the stellar populations in two fields lying at 20 and 23 kpc from the centre of M31 along the south-west semi-major axis. These data enable the construction of colour-magnitude diagrams reaching the oldest main-sequence turn-offs (~13 Gyr) which, when combined with another field at 25 kpc from our previous work, we use to derive the first precision constraints on the spatially-resolved star formation history of the M31 disc. The star formation rates exhibit temporal as well as field-to-field variations, but are generally always within a factor of two of their time average. There is no evidence of inside-out growth over the radial range probed. We find a median age of ~7.5 Gyr, indicating that roughly half of the stellar mass in the M31 outer disc was formed before z ~ 1. We also find that the age-metallicity relations (AMRs) are smoothly increasing from [Fe/H]~-0.4 to solar metallicity between 10 and 3 Gyr ago, contrary to the ...

  13. Powerful quasar outflow in a massive disc galaxy at $z \\sim 5$

    E-Print Network [OSTI]

    Curtis, Michael

    2015-01-01

    There is growing observational evidence of high-redshift quasars launching energetic, fast outflows, but the effects that these have on their host galaxies is poorly understood. We employ the moving-mesh code AREPO to study the feedback from a quasar that has grown to $\\sim 10^9 M_\\odot$ by $z \\sim 5$ and the impact that this has on its host galaxy. Our simulations use a super-Lagrangian refinement technique to increase the accuracy with which the interface of the quasar-driven wind and the surrounding gas is resolved. We find that the feedback injected in these simulations is less efficient at removing gas from the galaxy than in previous work using the same feedback strength, and that this leads to the growth of a massive, rotationally supported, star-forming disc, co-existing with a powerful quasar-driven outflow. The properties of our host galaxy, including the kinematical structure of the gaseous disc and of the outflow, are in good agreement with current observations. Upcoming ALMA and JWST observations...

  14. Inner disc rearrangement revealed by dramatic brightness variations in the young star PV Cep

    E-Print Network [OSTI]

    Kun, M; Moór, A; Kóspál, Á; Ábrahám, P; Apai, D; Kiss, Z T; Klagyivik, P; Magakian, T Yu; Mez\\Ho, Gy; Movsessian, T A; Pál, A; Rácz, M; Rogers, J

    2011-01-01

    Young Sun-like stars at the beginning of the pre-main sequence (PMS) evolution are surrounded by accretion discs and remnant protostellar envelopes. Photometric and spectroscopic variations of these stars are driven by interactions of the star with the disc. Time scales and wavelength dependence of the variability carry information on the physical mechanisms behind these interactions. We conducted multi-epoch, multi-wavelength study of PV Cep, a strongly variable, accreting PMS star. By combining our own observations from 2004-2010 with archival and literature data, we show that PV Cep started a spectacular fading in 2005, reaching an I_C-band amplitude of 4 mag. Analysis of variation of the optical and infrared fluxes, colour indices, and emission line fluxes suggests that the photometric decline in 2005-2009 resulted from an interplay between variable accretion and circumstellar extinction: since the central luminosity of the system is dominated by accretion, a modest drop in the accretion rate could induce...

  15. IEEE TRANSACTIONS ON MEDICAL IMAGING, VOL. 30, NO. 1, JANUARY 2011 1 Labeling of Lumbar Discs Using Both Pixel-and

    E-Print Network [OSTI]

    Chaudhary, Vipin

    structure detection and la- beling is a necessary step for various analysis tasks of the vertebral column of anal- ysis of the vertebral column structures such as disc size, disc shape, and water content.2047403 core requirement for the diagnosis of the vertebral column as a whole and for anatomical structures

  16. This page does not print. Please use front-and-back

    E-Print Network [OSTI]

    Duchowski, Andrew T.

    This page does not print. Please use front-and-back cover layout at end of file. #12;Craig Mahaffey's astonishing to realize that the same basic knowledge used to conserve a historic submarine can be applied

  17. The effects of laminar mixing on reaction fronts and patterns I. Introduction

    E-Print Network [OSTI]

    Solomon, Tom

    The effects of laminar mixing on reaction fronts and patterns I. Introduction A wide variety scales that are often smaller than a micron. For small Re, the flow is laminar; in this situation

  18. Vehicle Technologies Office Merit Review 2015: Magnesium-Intensive Front End Sub-Structure Development

    Broader source: Energy.gov [DOE]

    Presentation given by USAMP at 2015 DOE Hydrogen and Fuel Cells Program and Vehicle Technologies Office Annual Merit Review and Peer Evaluation Meeting about magnesium-intensive front end sub...

  19. Dynamic stabilization of Rayleigh-Taylor instability: Experiments with Newtonian fluids as surrogates for ablation fronts

    SciTech Connect (OSTI)

    Rodriguez Prieto, G.; Piriz, A. R.; Lopez Cela, J. J. [E.T.S.I. Industriales and Instituto de Investigaciones Energeticas (INEI), Universidad de Castilla-La Mancha, 13071 Ciudad Real (Spain); Tahir, N. A. [GSI Helmholtzzentrum fuer Schwerionenforschung, Planckstrasse 1, 64291 Darmstadt (Germany)

    2013-01-15

    A previous theory on dynamic stabilization of Rayleigh-Taylor instability at interfaces between Newtonian fluids is reformulated in order to make evident the analogy of this problem with the related one on dynamic stabilization of ablation fronts in the framework of inertial confinement fusion. Explicit analytical expressions are obtained for the boundaries of the dynamically stable region which turns out to be completely analogue to the stability charts obtained for the case of ablation fronts. These results allow proposing experiments with Newtonian fluids as surrogates for studying the case of ablation fronts. Experiments with Newtonian fluids are presented which demonstrate the validity of the theoretical approach and encourage to pursue experimental research on ablation fronts to settle the feasibility of dynamic stabilization in the inertial confinement fusion scenario.

  20. Modified Anti-de-Sitter Metric, Light-Front Quantized QCD, and...

    Office of Scientific and Technical Information (OSTI)

    Modified Anti-de-Sitter Metric, Light-Front Quantized QCD, and Conformal Quantum Mechanics Dosch, Hans Gunter; U. Heidelberg, ITP; Brodsky, Stanley J.; SLAC; de Teramond, Guy F.;...

  1. Toto the Robot Figure 1. Toto, front view. Figure 2. Toto, rear view.

    E-Print Network [OSTI]

    Indiana University

    Toto the Robot Figure 1. Toto, front view. Figure 2. Toto, rear view. Toto the Robot was created so a robot, helps account for his lack of verbal charm. Second, some younger children may recognize in Toto

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

    E-Print Network [OSTI]

    Stefanopoulou, Anna

    Nitrogen Front Evolution in Purged Polymer Electrolyte Membrane Fuel Cell with Dead-Ended Anode plugging of the channels, and flooding of the gas diffusion layer. The observation of each phenomenon

  3. Front Solutions for Bistable Differential-Difference Equations with Inhomogeneous Diffusion

    E-Print Network [OSTI]

    Humphries, A. R.; Moore, Brian E.; Van Vleck, Erik

    2011-08-09

    We consider a bistable differential-difference equation with inhomogeneous diffusion. Employing a piecewise linear nonlinearity, often referred to as McKean's caricature of the cubic, we construct front solutions which ...

  4. Low-Cost Differential Front-End for Doppler Radar Vital Sign Monitoring

    E-Print Network [OSTI]

    Fletcher, Richard Ribon

    We present a differential front end design for improving the performance of short-range low-cost Doppler radars for vital sign detection with application to automotive driver safety systems, health monitoring, and security ...

  5. The Gaia-ESO Survey: Characterisation of the [alpha/Fe] sequences in the Milky Way discs

    E-Print Network [OSTI]

    Kordopatis, G; Gilmore, G; Recio-Blanco, A; de Laverny, P; Hill, V; Adibekyan, V; Heiter, U; Minchev, I; Famaey, B; Bensby, T; Feltzing, S; Guiglion, G; Korn, A J; Mikolaitis, S; Vallenari, A; Bayo, A; Carraro, G; Flaccomio, E; Franciosini, E; Hourihane, A; Jofre, P; Koposov, S E; Lardo, C; Lewis, J; Lind, K; Magrini, L; Morbidelli, L; Pancino, E; Randich, S; Sacco, G G; Worley, C C; Zaggia, S

    2015-01-01

    We investigate, using the Gaia-ESO Survey internal Data-Release 2, the properties of the double sequence of the Milky Way discs (defined chemically as the high-alpha and low-alpha populations), and discuss their compatibility with discs defined by other means such as metallicity, kinematics or positions. This investigation uses two different approaches: in velocity space for stars located in the extended Solar neighbourhood, and in chemical space for stars at different ranges of Galactocentric radii and heights from the plane. The separation we find in velocity space allows us to investigate, in a novel manner, the extent in metallicity of each of the two sequences, identifying them with the two discs, without making any assumption about the shape of their metallicity distribution functions. Then, using the separation in chemical space, we characterise the spatial variation of the slopes of the [alpha/Fe] - [Fe/H] sequences for the thick and thin discs and the way in which the relative proportions of the two ...

  6. Doppler-imaging of the planetary debris disc at the white dwarf SDSS J122859.93+104032.9

    E-Print Network [OSTI]

    Manser, Christopher J; Marsh, Thomas R; Veras, Dimitri; Koester, Detlev; Breedt, Elmé; Pala, Anna F; Parsons, Steven G; Southworth, John

    2015-01-01

    Debris discs which orbit white dwarfs are signatures of remnant planetary systems. We present twelve years of optical spectroscopy of the metal-polluted white dwarf SDSS J1228+1040, which shows a steady variation in the morphology of the 8600 {\\AA} Ca II triplet line profiles from the gaseous component of its debris disc. We identify additional emission lines of O I, Mg I, Mg II, Fe II and Ca II in the deep co-added spectra. These emission features (including Ca H & K) exhibit a wide range in strength and morphology with respect to each other and to the Ca II triplet, indicating different intensity distributions of these ionic species within the disc. Using Doppler tomography we show that the evolution of the Ca II triplet profile can be interpreted as the precession of a fixed emission pattern with a period in the range 24-30 years. The Ca II line profiles vary on time-scales that are broadly consistent with general relativistic precession of the debris disc.

  7. Data Min Knowl Disc (2011) 23:169214 DOI 10.1007/s10618-010-0202-x

    E-Print Network [OSTI]

    Antwerpen, Universiteit

    2011-01-01

    Data Min Knowl Disc (2011) 23:169­214 DOI 10.1007/s10618-010-0202-x KRIMP: mining itemsets access at Springerlink.com Abstract One of the major problems in pattern mining is the explosionM, Department of Mathematics and Computer Science, Faculty of Science, University of Antwerp, Antwerp, Belgium

  8. Line Ratio Diagnostics along the Disc of Two Edge-on Lentic-ular Galaxies, NGC 4710 and NGC 5866

    E-Print Network [OSTI]

    Bureau, Martin

    . Topal, M. Bureau (University of Oxford, United Kingdom), T. A. Davis (ESO, Germany), L. M. Young (New. The unique X-shape (two-component velocity distributions indicating a nuclear disc and inner ring) position as a function of projected radius along the velocity components. We study the gas physical conditions of a two

  9. Semi-flexible gas-insulated transmission line using sandwiched discs for intermittent flexing joints

    DOE Patents [OSTI]

    Kommineni, Prasad R. (Westboro, MA)

    1983-02-15

    A gas-insulated transmission line includes an outer sheath, an inner conductor, an insulating gas electrically insulating the inner conductor from the outer sheath, and insulating supports insulatably supporting the inner conductor within the outer sheath. The inner conductor is provided with flexibility by the use of main conductor sections which are joined together through a conductor hub section and flexible flexing elements. Stress shields are provided to control the electric field at the locations of the conductor hub sections where the insulating supports are contacting the inner conductor. The flexing elements are formed by sandwiching together, by fusing, a pair of thin hollow discs which are fixedly secured to both the main conductor sections and the conductor hub section.

  10. Semi-flexible gas-insulated transmission line using sandwiched discs for intermittent flexing joints

    DOE Patents [OSTI]

    Kommineni, P.R.

    1983-02-15

    A gas-insulated transmission line includes an outer sheath, an inner conductor, an insulating gas electrically insulating the inner conductor from the outer sheath, and insulating supports insulatably supporting the inner conductor within the outer sheath. The inner conductor is provided with flexibility by the use of main conductor sections which are joined together through a conductor hub section and flexible flexing elements. Stress shields are provided to control the electric field at the locations of the conductor hub sections where the insulating supports are contacting the inner conductor. The flexing elements are formed by sandwiching together, by fusing, a pair of thin hollow discs which are fixedly secured to both the main conductor sections and the conductor hub section. 4 figs.

  11. The orbital poles of Milky Way satellite galaxies: a rotationally supported disc-of-satellites

    E-Print Network [OSTI]

    Manuel Metz; Pavel Kroupa; Noam I. Libeskind

    2008-02-26

    Available proper motion measurements of Milky Way (MW) satellite galaxies are used to calculate their orbital poles and projected uncertainties. These are compared to a set of recent cold dark-matter (CDM) simulations, tailored specifically to solve the MW satellite problem. We show that the CDM satellite orbital poles are fully consistent with being drawn from a random distribution, while the MW satellite orbital poles indicate that the disc-of-satellites of the Milky Way is rotationally supported. Furthermore, the bootstrapping analysis of the spatial distribution of theoretical CDM satellites also shows that they are consistent with being randomly drawn. The theoretical CDM satellite population thus shows a significantly different orbital and spatial distribution than the MW satellites, most probably indicating that the majority of the latter are of tidal origin rather than being DM dominated sub-structures. A statistic is presented that can be used to test a possible correlation of satellite galaxy orbits with their spatial distribution.

  12. AdS/QCD and Applications of Light-Front Holography

    SciTech Connect (OSTI)

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

    2012-02-16

    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.

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

    DOE Patents [OSTI]

    Battiste, Richard L. (Oak Ridge, TN)

    2007-12-25

    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.

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

    DOE Patents [OSTI]

    Battiste, Richard L

    2013-12-31

    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 th emold space through the openings, the fluid experiencing a dynamic fluid front while filling the mold space with a fluid; and characterizing temporal-spatial properties of the dynamic fluid front by monitoring a termperature 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 th emold 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.

  15. Deep Chandra observation and numerical studies of the nearest cluster cold front in the sky

    E-Print Network [OSTI]

    Werner, N; Zhuravleva, I; Ichinohe, Y; Simionescu, A; Allen, S W; Markevitch, M; Fabian, A C; Keshet, U; Roediger, E; Ruszkowski, M; Sanders, J S

    2015-01-01

    We present the results of a very deep (500 ks) Chandra observation, along with tailored numerical simulations, of the nearest, best resolved cluster cold front in the sky, which lies 90 kpc (19 arcmin) to the northwest of M 87. The northern part of the front appears the sharpest, with a width smaller than 2.5 kpc (1.5 Coulomb mean free paths; at 99 per cent confidence). Everywhere along the front, the temperature discontinuity is narrower than 4-8 kpc and the metallicity gradient is narrower than 6 kpc, indicating that diffusion, conduction and mixing are suppressed across the interface. Such transport processes can be naturally suppressed by magnetic fields aligned with the cold front. However, the northwestern part of the cold front is observed to have a nonzero width. The broadening is consistent with the presence of Kelvin-Helmholtz instabilities (KHI) on length scales of a few kpc. Based on comparison with simulations, the presence of KHI would imply that the effective viscosity of the intra-cluster medi...

  16. Two: Standing in Front of the California Ballot-Box Train: The Present and Past of Ballot-Box Budgeting

    E-Print Network [OSTI]

    Mitchell, Daniel J.B.; Hirsch, Werner Z.

    2006-01-01

    STANDING IN FRONT OF THE CALIFORNIA BALLOT TRAIN: THEdecline of the Governor’s standing in various polls. Thethe Paterno case. 87 Standing in the background were

  17. Apparatus and method for phase fronts based on superluminal polarization current

    DOE Patents [OSTI]

    Singleton, John (Los Alamos, NM); Ardavan, Houshang (Cambridge, GB); Ardavan, Arzhang (Cambridge, GB)

    2012-02-28

    An apparatus and method for a radiation source involving phase fronts emanating from an accelerated, oscillating polarization current whose distribution pattern moves superluminally (that is, faster than light in vacuo). Theoretical predictions and experimental measurements using an existing prototype superluminal source show that the phase fronts from such a source can be made to be very complex. Consequently, it will be very difficult for an aircraft imaged by such a radiation to detect where this radiation has come from. Moreover, the complexity of the phase fronts makes it almost impossible for electronics on an aircraft to synthesize a rogue reflection. A simple directional antenna and timing system should, on the other hand, be sufficient for the radar operators to locate the aircraft, given knowledge of their own source's speed and modulation pattern.

  18. Granular front formation in free-surface flow of concentrated suspensions

    E-Print Network [OSTI]

    Leonardi, A; Wittel, F K; Kaitna, R; Mendoza, M; Wu, W; Herrmann, H J

    2015-01-01

    Granular fronts are a common yet unexplained phenomenon emerging during the gravity driven free-surface flow of concentrated suspensions. They are usually believed to be the result of fluid convection in combination with particle size segregation. However, suspensions composed of uniformly sized particles also develop a granular front. Within a large rotating drum, a stationary recirculating avalanche is generated. The flowing material is a mixture of a visco-plastic fluid obtained from a kaolin-water dispersion, with spherical ceramic particles denser than the fluid. The goal is to mimic the composition of many common granular-fluid materials, like fresh concrete or debris flow. In these materials, granular and fluid phases have the natural tendency to segregate due to particle settling. However, through the shearing caused by the rotation of the drum, a reorganization of the phases is induced, leading to the formation of a granular front. By tuning the material properties and the drum velocity, it is possib...

  19. A Model for Tracking Fronts of Stress-Induced Permeability Enhancement

    E-Print Network [OSTI]

    K. C. Lewis; Satish Karra; Sharad Kelkar

    2013-05-15

    Using an analogy to the classical Stefan problem, we construct evolution equations for the fluid pore pressure on both sides of a propagating stress-induced damage front. Closed form expressions are derived for the position of the damage front as a function of time for the cases of thermally-induced damage as well as damage induced by over-pressure. We derive expressions for the flow rate during constant pressure fluid injection from the surface corresponding to a spherically shaped subsurface damage front. Finally, our model results suggest an interpretation of field data obtained during constant pressure fluid injection over the course of 16 days at an injection site near Desert Peak, NV.

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

    SciTech Connect (OSTI)

    Brett Carlsen; Emily Tavrides; Erich Schneider

    2010-08-01

    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.

  1. On the movement of a liquid front in an unsaturated, fractured porous medium, Part 1

    SciTech Connect (OSTI)

    Nitao, J.J.; Buscheck, T.A.

    1989-06-01

    The primary aim of this paper is to present approximate analytical solutions of the fracture flow which gives the position of the liquid fracture front as a function of time. These solutions demonstrate that the liquid movement in the fracture can be classified into distinctive time periods, or flow regimes. It is also shown that when plotted versus time using a log-log scale, the liquid fracture front position asymptotically approaches a series of line segments. Two-dimensional numerical simulations were run utilizing input data applicable to the densely welded, fractured tuff found at Yucca Mountain in order to confirm these observations. 19 refs., 15 figs., 8 tabs.

  2. A new approach to front-end electronics interfacing in the ATLAS experiment

    E-Print Network [OSTI]

    Anderson, John Thomas; The ATLAS collaboration; Boterenbrood, Hendrik; Chen, Hucheng; Chen, Kai; Drake, Gary; Donszelmann, Mark; Francis, David; Gorini, Benedetto; Lanni, Francesco; Lehmann Miotto, Giovanna; Levinson, Lorne; Narevicius, Julia; Roich, Alexander; Ryu, Soo; Schreuder, Frans Philip; Schumacher, J\\"orn; Vandelli, Wainer; Vermeulen, Jos; Wu, Weihao; Zhang, Jinlong

    2015-01-01

    For new detector and trigger systems to be installed in the ATLAS experiment after LHC Run 2, a new approach will be followed for Front-End electronics interfacing. The FELIX (Front-End LInk eXchange) system will function as gateway connecting: on one side to detector and trigger electronics links, as well as providing timing and trigger (TTC) information; and on the other side a commodity switched network built using standard technology (either Ethernet or Infiniband). The new approach is described in this paper, and results achieved so far are presented.

  3. Eddy conductivity in and near dry cold fronts in the layer, 70 to 1270 feet 

    E-Print Network [OSTI]

    Conlan, Edward Francis

    1965-01-01

    EDDY CONDUCTIVITY IN AND NEAR DRY COLD FRONTS IN THE LAYER, 70 TO 1270 FEET A Thesis By EDWARD FRANCIS CONLAN Captain, USAF Submitted to the Graduate College of Texas A&M University in partial fulfillment of the requirements for the degree... of MASTER OF SCIENCE January 1965 Major Subject: METEOROLOGY EDDY CONDUCTIVITY IN AND NEAR DRY COLD FRONTS IN THE LAYER) 70 TO 1270 FEET A Thesis By EDWARD FRANCIS CONLAN Captain, USAF Approved as to style and content by: i J 8~. . c6~h arrmanf o...

  4. Standing spin-wave mode structure and linewidth in partially disordered hexagonal arrays of perpendicularly magnetized sub-micron Permalloy discs

    SciTech Connect (OSTI)

    Ross, N. Kostylev, M.; Stamps, R. L.

    2014-09-21

    Standing spin wave mode frequencies and linewidths in partially disordered perpendicular magnetized arrays of sub-micron Permalloy discs are measured using broadband ferromagnetic resonance and compared to analytical results from a single, isolated disc. The measured mode structure qualitatively reproduces the structure expected from the theory. Fitted demagnetizing parameters decrease with increasing array disorder. The frequency difference between the first and second radial modes is found to be higher in the measured array systems than predicted by theory for an isolated disc. The relative frequencies between successive spin wave modes are unaffected by reduction of the long-range ordering of discs in the array. An increase in standing spin wave resonance linewidth at low applied magnetic fields is observed and grows more severe with increased array disorder.

  5. The Influence of a Kinematically Cold Young Component on Disc-Halo Decompositions in Spiral Galaxies: Insights from Solar Neighbourhood K-giants

    E-Print Network [OSTI]

    Aniyan, S; Gerhard, O E; Arnaboldi, M; Flynn, C

    2015-01-01

    In decomposing the HI rotation curves of disc galaxies, it is necessary to break a degeneracy between the gravitational fields of the disc and the dark halo by estimating the disc surface density. This is done by combining measurements of the vertical velocity dispersion of the disc with the disc scale height. The vertical velocity dispersion of the discs is measured from absorption lines (near the V-band) of near-face-on spiral galaxies, with the light coming from a mixed population of giants of all ages. However, the scale heights for these galaxies are estimated statistically from near-IR surface photometry of edge-on galaxies. The scale height estimate is therefore dominated by a population of older (> 2 Gyr) red giants. In this paper, we demonstrate the importance of measuring the velocity dispersion for the same older population of stars that is used to estimate the vertical scale height. We present an analysis of the vertical kinematics of K-giants in the solar vicinity. We find the vertical velocity d...

  6. The Origin of UV-optical Variability in AGN and Test of Disc Models: XMM-Newton and ground based observations of NGC4395

    E-Print Network [OSTI]

    McHardy, Ian; Peterson, Brad; Bieryla, Allyson; Chand, Hum; Elvis, Martin; Emmanoulopoulos, Dimitrios; Falco, Emilio; Gandhi, Poshak; Kaspi, Shai; Latham, David; Lira, Paulina; McCully, Curtis; Netzer, Hagai; Uemura, Makoto

    2016-01-01

    The origin of short timescale (weeks/months) variability of AGN, whether due to intrinsic disc variations or reprocessing of X-ray emission by a surrounding accretion disc, has been a puzzle for many years. However recently a number of observational programmes, particularly of NGC5548 with Swift, have shown that the UV/optical variations lag behind the X-ray variations in a manner strongly supportive of X-ray reprocessing. Somewhat surprisingly the implied size of the accretion disc is ~3x greater than expected from a standard, smooth, Shakura-Sunyaev thin disc model. Although the difference may be explained by a clumpy accretion disc, it is not clear whether the difference will occur in all AGN or whether it may change as, eg, a function of black hole mass, accretion rate or disc temperature. Measurements of interband lags for most AGN require long timescale monitoring, which is hard to arrange. However for low mass (solar mass) AGN, the combination of XMM-Newton EPIC (X-rays) with the optical ...

  7. Automated Kinematic Modelling of Warped Galaxy Discs in Large Hi Surveys: 3D Tilted Ring Fitting of HI Emission Cubes

    E-Print Network [OSTI]

    Kamphuis, P; Oh, S- H; Spekkens, K; Urbancic, N; Serra, P; Koribalski, B S; Dettmar, R -J

    2015-01-01

    Kinematical parameterisations of disc galaxies, employing emission line observations, are indispensable tools for studying the formation and evolution of galaxies. Future large-scale HI surveys will resolve the discs of many thousands of galaxies, allowing a statistical analysis of their disc and halo kinematics, mass distribution and dark matter content. Here we present an automated procedure which fits tilted-ring models to Hi data cubes of individual, well-resolved galaxies. The method builds on the 3D Tilted Ring Fitting Code (TiRiFiC) and is called FAT (Fully Automated TiRiFiC). To assess the accuracy of the code we apply it to a set of 52 artificial galaxies and 25 real galaxies from the Local Volume HI Survey (LVHIS). Using LVHIS data, we compare our 3D modelling to the 2D modelling methods DiskFit and rotcur. A conservative result is that FAT accurately models the kinematics and the morphologies of galaxies with an extent of eight beams across the major axis in the inclination range 20$^{\\circ}$-90$^{...

  8. 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]

    Giovanni Santostasi

    2008-07-16

    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.

  9. Classical T Tauri stars: magnetic fields, coronae, and star-disc interactions

    E-Print Network [OSTI]

    Johnstone, C P; Gregory, S G; Donati, J -F; Hussain, G

    2013-01-01

    The magnetic fields of young stars set their coronal properties and control their spin evolution via the star-disc interaction and outflows. Using 14 magnetic maps of 10 classical T Tauri stars (CTTSs) we investigate their closed X-ray emitting coronae, their open wind-bearing magnetic fields, and the geometry of magnetospheric accretion flows. The magnetic fields of all the CTTSs are multipolar. Stars with simpler (more dipolar) large-scale magnetic fields have stronger fields, are slower rotators, and have larger X-ray emitting coronae compared to stars with more complex large-scale magnetic fields. The field complexity controls the distribution of open and closed field regions across the stellar surface, and strongly influences the location and shapes of accretion hot spots. However, the higher order field components are of secondary importance in determining the total unsigned open magnetic flux, which depends mainly on the strength of the dipole component and the stellar surface area. Likewise, the dipol...

  10. Pinning and mode-locking of reaction fronts by vortices Garrett M. O'Malley, Matthew S. Paoletti 1

    E-Print Network [OSTI]

    Solomon, Tom

    not understood, even for well-ordered, laminar flows. In many cases, transport in a fluid flow is diffusive­diffusion (RD) limit with no fluid flows, the speed at which a reaction front propagates was predicted involved in the reaction [7,11]. The effects of fluid flows on front behavior, however, is still

  11. Chemical Reaction Fronts in Ordered and Disordered Cellular Flows with Opposing Winds M. E. Schwartz* and T. H. Solomon

    E-Print Network [OSTI]

    Ligare, Martin

    simply propagates at its reaction-diffusion (no flow) velocity minus the wind speed. If the same wind-dependent flows as well. In the absence of fluid flows, a front propagates with a reaction-diffusion (RD) velocityChemical Reaction Fronts in Ordered and Disordered Cellular Flows with Opposing Winds M. E

  12. Sensitivity of Mesoscale Gravity Waves to the Baroclinicity of Jet-Front Systems SHUGUANG WANG AND FUQING ZHANG

    E-Print Network [OSTI]

    Sensitivity of Mesoscale Gravity Waves to the Baroclinicity of Jet-Front Systems SHUGUANG WANG of mesoscale gravity waves to the baroclinicity of the background jet-front systems by simulating different life cycles of baroclinic waves with a high-resolution mesoscale model. Four simulations are made

  13. 41On the Water Front I Dr. Peter H. Gleick and Ms. Meena Palaniappan Palaniappan

    E-Print Network [OSTI]

    by a growing competition for water, increasing ecological degradation associated with human extraction of water41On the Water Front I Dr. Peter H. Gleick and Ms. Meena Palaniappan Ms. Meena Palaniappan Director, International Water and Communities Initiative Pacific Institute for Studies in Development, Environment

  14. Stable or unstable wetting fronts in water repellent soils effect of antecedent soil moisture content

    E-Print Network [OSTI]

    Walter, M.Todd

    contents during the experiment, which caused the soil to be wettable instead of water repellent. The waterStable or unstable wetting fronts in water repellent soils ± effect of antecedent soil moisture content Coen J. Ritsemaa,* , John L. Nieberb , Louis W. Dekkera , T.S. Steenhuisc a DLO Winand Staring

  15. Green radio despite "Dirty RF" front-end Myriam Ariaudo*1

    E-Print Network [OSTI]

    Fijalkow, Inbar

    design, which reduces the chip area and the number of components (Green #12;design) or facilitate. Concerning the RF part, designing a Green radio first consists in the improvement of efficiency. It is well front-end imperfections can participate in the design of Green radio. Some of these corrections enable

  16. Light-Like Noncommutativity, Light-Front Quantization and New Light on UV/IR Mixing

    E-Print Network [OSTI]

    M. M. Sheikh-Jabbari; A. Tureanu

    2010-10-02

    We revisit the problem of quantizing field theories on noncommutative Moyal spacetime with \\emph{light-like} noncommutativity. To tackle the issues arising from noncommuting and hence nonlocal time, we argue that for this case light-front quantization procedure should be employed. In this appropriate quantization scheme we perform the non-planar loop analysis for the light-like noncommutative field theories. One of the important and peculiar features of light-front quantization is that the UV cutoff of the light-cone Hamiltonian manifests itself as an IR cutoff for the light-cone momentum, $p^+$. Due to this feature, the naive results of covariant quantization for the light-like case allude to the absence of the UV/IR mixing in the light-front quantization. However, by a careful analysis of non-planar loop integrals we show that this is not the case and the UV/IR mixing persists. In addition, we argue in favour of the perturbative unitarity of light-like noncommutative field theories in the light-front quantization scheme.

  17. Correction to "Precursor activation and substorm expansion associated with observations of a dipolarization front by Thermal

    E-Print Network [OSTI]

    California at Berkeley, University of

    Correction to "Precursor activation and substorm expansion associated with observations of a dipolarization front by Thermal Emission Imaging System (THEMIS)" C. L. Tang, V. Angelopoulos, A. Runov, C. T, K. H. Fornacon, and Z. Y. Li (2010), Correction to "Precursor activation and substorm expansion

  18. Stability of negative ionization fronts: Regularization by electric screening? Manuel Arrayas1,2

    E-Print Network [OSTI]

    Ebert, Ute

    investigate how transversal Fourier modes of a planar ionization front are regularized by the electric the formation of cusps. The nature of this regularization has to be derived from the underlying gas discharge physics; it recently has been a subject of debate 13,14 . We argue that one regular- ization mechanism

  19. Granular front formation in free-surface flow of concentrated suspensions

    E-Print Network [OSTI]

    A. Leonardi; M. Cabrera; F. K. Wittel; R. Kaitna; M. Mendoza; W. Wu; H. J. Herrmann

    2015-02-19

    Granular fronts are a common yet unexplained phenomenon emerging during the gravity driven free-surface flow of concentrated suspensions. They are usually believed to be the result of fluid convection in combination with particle size segregation. However, suspensions composed of uniformly sized particles also develop a granular front. Within a large rotating drum, a stationary recirculating avalanche is generated. The flowing material is a mixture of a visco-plastic fluid obtained from a kaolin-water dispersion, with spherical ceramic particles denser than the fluid. The goal is to mimic the composition of many common granular-fluid materials, like fresh concrete or debris flow. In these materials, granular and fluid phases have the natural tendency to segregate due to particle settling. However, through the shearing caused by the rotation of the drum, a reorganization of the phases is induced, leading to the formation of a granular front. By tuning the material properties and the drum velocity, it is possible to control this phenomenon. The setting is reproduced in a numerical environment, where the fluid is solved by a Lattice-Boltzmann Method, and the particles are explicitly represented using the Discrete Element Method. The simulations confirm the findings of the experiments, and provide insight into the internal mechanisms. Comparing the time-scale of particle settling with the one of particle recirculation, a non-dimensional number is defined, and is found to be effective in predicting the formation of a granular front.

  20. An analytical approach to initiation of propagating fronts I. Idris and V. N. Biktashev

    E-Print Network [OSTI]

    Biktashev, Vadim N.

    situations as self­ heating in metals and superconductors, phase transitions, combustion and other chemical, but an above­threshold per­ turbation can create a propagating pulse wave of finite length and duration, in the wake of which the system returns to the resting state. The front of an excitable pulse is often

  1. An analytical approach to initiation of propagating fronts I. Idris and V. N. Biktashev

    E-Print Network [OSTI]

    Biktashev, Vadim N.

    situations as self- heating in metals and superconductors, phase transitions, combustion and other chemical, but an above-threshold per- turbation can create a propagating pulse wave of finite length and duration, in the wake of which the system returns to the resting state. The front of an excitable pulse is often

  2. Hierarchical Modelling of Automotive Sensor Front-Ends For Structural Diagnosis of Aging Faults

    E-Print Network [OSTI]

    Wieringa, Roel

    functions previously handled purely mechanical. In addition hybrid and pure electrical cars are emerging are hybrid and electrical cars. The automotive semiconductor elec- tronics market amounted to 19.5 billion for the development of dependable analogue/mixed-signal car front-ends, by interfacing aging models between different

  3. Photo-isomerization fronts in dye-doped nematic liquid crystals

    E-Print Network [OSTI]

    Gavilan, Marcel G. Clerc

    Photo-isomerization fronts in dye-doped nematic liquid crystals V. Odent,1, * M. G. Clerc,1 C study of the photo-isomerization dynamics in dye-doped nematic crystals is reported, which shows that and thus induc- ing a photo-controlled optical aperture. The optical intensity and temperature fields

  4. Measurement of freezing point depression of water in glass capillaries and the associated ice front shape

    E-Print Network [OSTI]

    Wan, Richard G.

    Measurement of freezing point depression of water in glass capillaries and the associated ice front Variations of the Kelvin equation W. Thomson, Philos. Mag. 42, 448 1871 to describe the freezing point. The capillary freezing point depression for glass tubes with radii of 87 m­3 m was successfully measured

  5. Export of Asian pollution during two cold front episodes of the TRACE-P experiment

    E-Print Network [OSTI]

    Palmer, Paul

    Export of Asian pollution during two cold front episodes of the TRACE-P experiment C. Mari how these cyclonic systems have impacted the export of pollution out of the Asian continent. We of pollution are met during flight 13 (i.e., the occurrences of the warm conveyor belt near the source regions

  6. Nucleon and flavor form factors in a light front quark model in AdS/QCD

    E-Print Network [OSTI]

    Dipankar Chakrabarti; Chandan Mondal

    2013-12-05

    Using the light front wave functions for the nucleons in a quark model in AdS/QCD, we calculate the nucleon electromagnetic form factors. The flavor decompositions of the nucleon form factors are calculated from the GPDs in this model. We show that the nucleon form factors and their flavor decompositions calculated in AdS/QCD are in agreement with experimental data.

  7. Dynamical evolution of RayleighTaylor and RichtmyerMeshkov mixing fronts Baolian Cheng

    E-Print Network [OSTI]

    New York at Stoney Brook, State University of

    derive an analytic solution for the dynamic evolution of mixing fronts driven by constant acceleration system produce buoyancy and shear driven instabilities at an interface between distinct fluids #1 Rayleigh­Taylor #RT# and impulsive acceleration Richtmyer­Meshkov instabilities, from a simple physics

  8. Pulse-front tilt created in misaligned dispersionless optical systems and correct interferometric

    E-Print Network [OSTI]

    Dreischuh, Alexander

    Pulse-front tilt created in misaligned dispersionless optical systems and correct interferometric-temporal distortions of ultrashort laser pulses. Special attention is given to the possible creation of a pulse of the ultrashort pulses in the presence of an arbitrary PFT . Key words: spatio-temporal distortion, dispersionless

  9. InertiaGravity Waves Spontaneously Generated by Jets and Fronts. Part I: Different Baroclinic Life Cycles

    E-Print Network [OSTI]

    Plougonven, Riwal

    Inertia­Gravity Waves Spontaneously Generated by Jets and Fronts. Part I: Different Baroclinic Life the initial zonal jet. The wave generation depends strongly on the details of the baroclinic wave of waves being generated. These studies agree with evi- dence from observations [e.g., the key role of jet

  10. Why are there stationary EIT wave fronts Chen, P. F. a

    E-Print Network [OSTI]

    Chen, P. F.

    -8471, Japan Abstract EIT waves are often observed to be propagating EUV enhancements followed by an expanding in the framework of our model where "EIT waves" are supposed to be generated by successive opening of the fieldWhy are there stationary EIT wave fronts Chen, P. F. a , C. Fang a , K. Shibata b a

  11. Turbulent premixed flame front dynamics and implications for limits of flamelet hypothesis

    E-Print Network [OSTI]

    Gülder, Ömer L.

    of methane­air and propane­air stabilized on a Bunsen-type burner were studied to investigate the dynamics. The equivalence ratio was varied from 0.6 (0.7 for propane) to stoichiometric. The flame front data were obtained The Combustion Institute. Published by Elsevier Inc. All rights reserved. Keywords: Turbulent premixed flames

  12. Coherent States and Spontaneous Symmetry Breaking in Light Front Scalar Field Theory

    SciTech Connect (OSTI)

    Vary, J.P.; Chakrabarti, D.; Harindranath, A.; Lloyd, R.; Martinovic, L.; Spence, J.R.; /Iowa State U.

    2005-12-14

    Recently developed nuclear many-body techniques provide novel results when applied to constituent quark models and to light-front scalar field theory. We show how spontaneous symmetry breaking arises and is consistent with a coherent state ansatz in a variational treatment. The kink and the kink-antikink topological features are identified and the onset of symmetry restoration is demonstrated.

  13. Bloch-Front Turbulence in a Periodically Forced Belousov-Zhabotinsky Reaction Bradley Marts,1

    E-Print Network [OSTI]

    Meron, Ehud

    , Los Alamos, New Mexico 87545, USA 3 Department of Solar Energy and Environmental Physics, BIDR, Ben involving continual events of spiral-vortex nucleation and destruction. Using the amplitude equation for forced oscillatory systems and the normal form equations for a curved front line, we identify

  14. Sensitivity of mesoscale gravity waves to the baroclinicity of jet-front systems 

    E-Print Network [OSTI]

    Wang, Shuguang

    2006-04-12

    To investigate the generation of mesoscale gravity waves from upper-tropospheric jet-front systems, five different life cycles of baroclinic waves are simulated with a high-resolution mesoscale model (MM5 with 10-km grid spacing). The baroclinicity...

  15. Rapid uplift of nonmethane hydrocarbons in a cold front over central Europe

    E-Print Network [OSTI]

    Hoskins, Brian

    Rapid uplift of nonmethane hydrocarbons in a cold front over central Europe R. M. Purvis,1 A. C of 21 C2­C7 nonmethane hydrocarbons (NMHCs) has been determined in planetary boundary layer (PBL between the PBL and FT was observed for all short and medium lifetime hydrocarbons (e.g., average iso

  16. Local waiting time fluctuations along a randomly pinned crack front Knut Jrgen Maly,1

    E-Print Network [OSTI]

    Toussaint, Renaud

    that the fracture front dynamics is governed by local and irregular avalanches with very large size and velocity a characteristic length scale of disorder Ld 15µm, the avalanche clusters become anisotropic, and the scaling- ting contact lines [13­15], where elasticity and disorder compete to shape the interface. In order

  17. Local Waiting Time Fluctuations along a Randomly Pinned Crack Front Knut Jrgen Maly,1

    E-Print Network [OSTI]

    Schmittbuhl, Jean

    is followed using a high resolution fast camera. We show that the fracture front dynamics is governed by local:7 0:1. Above a characteristic length scale of disorder Ld 15 m, the avalanche clusters become elas- ticity and disorder compete to shape the interface. In order to shed some light

  18. The Influence of an SST Front on a Heavy Rainfall Event Over Coastal Taiwan During

    E-Print Network [OSTI]

    Johnson, Richard H.

    1 The Influence of an SST Front on a Heavy Rainfall Event Over Coastal Taiwan During TiMREX Michael-lived heavy precipitation area was observed along the southwest coast of Taiwan3 from 13-18 June 2008 during in the sea surface temperature (SST) off the southwest coast of8 Taiwan existed during the rainfall event

  19. A NOTE ON FRONT TRACKING AND THE EQUIVALENCE BETWEEN VISCOSITY SOLUTIONS OF HAMILTON-JACOBI EQUATIONS

    E-Print Network [OSTI]

    A NOTE ON FRONT TRACKING AND THE EQUIVALENCE BETWEEN VISCOSITY SOLUTIONS OF HAMILTON-JACOBI solution of the Hamilton-Jacobi equation u t + H(ux ) = 0. In our proof we work directly with the de#12 conservation laws to Hamilton-Jacobi equations and derive some of its properties. 1. Introduction It is well

  20. Tracking the Salt Front: Teacher's Section Page 1 Hudson River Estuary Program

    E-Print Network [OSTI]

    Lance, Veronica P.

    on each tide cycle. The front's location is given in Hudson River Miles (HRM), starting at the southern tip of Manhattan. This spot, called The Battery, is HRM 0. Ocean tides influence the Hudson north to the Federal Dam at Troy (HRM 153). Activity: 1. In preparation for this lesson, have students do the ELA

  1. Steady-state propagation speed of rupture fronts along 1D frictional interfaces

    E-Print Network [OSTI]

    Amundsen, David Skålid; Thøgersen, Kjetil; Katzav, Eytan; Malthe-Sørenssen, Anders; Scheibert, Julien

    2015-01-01

    The rupture of dry frictional interfaces occurs through the propagation of fronts breaking the contacts at the interface. Recent experiments have shown that the velocities of these rupture fronts range from quasi-static velocities proportional to the external loading rate to velocities larger than the shear wave speed. The way system parameters influence front speed is still poorly understood. Here we study steady-state rupture propagation in a 1D spring-block model of an extended frictional interface, for various friction laws. With the classical Amontons--Coulomb friction law, we derive a closed-form expression for the steady-state rupture velocity as a function of the interfacial shear stress just prior to rupture. We then consider an additional shear stiffness of the interface and show that the softer the interface, the slower the rupture fronts. We provide an approximate closed form expression for this effect. We finally show that adding a bulk viscosity on the relative motion of blocks accelerates stead...

  2. Propagation in a kinetic reaction-transport equation: travelling waves and accelerating fronts

    E-Print Network [OSTI]

    Calvez, Vincent

    describes particles moving according to a velocity-jump process, and proliferating thanks to a reaction termPropagation in a kinetic reaction-transport equation: travelling waves and accelerating fronts the existence and stability of travelling wave solutions of a kinetic reaction- transport equation. The model

  3. Nonuniform reaction rate distribution for the generalized Fisher equation: Ignition ahead of the reaction front

    E-Print Network [OSTI]

    Fedotov, Sergei

    equation involving diffusion transport with a finite velocity and a spatially nonuniform reaction rate. WeNonuniform reaction rate distribution for the generalized Fisher equation: Ignition ahead of the reaction front Sergei Fedotov* Department of Mathematics, UMIST, Manchester M60 1QD, United Kingdom

  4. Front speed enhancement in cellular flows Institute of Physics, Potsdam University, 14415 Potsdam, Germany

    E-Print Network [OSTI]

    Cencini, Massimo

    .g., in combustion. However, many features can be understood by neglecting the back-reaction on the velocity field flows in three different regimes: slow reaction, fast reaction and geometrical optics limit. It is well speed as a function of the stirring intensity, U. For slow reaction, the front propagates with a speed

  5. Front propagation in a kinetic reaction-transport equation Emeric Bouin

    E-Print Network [OSTI]

    Boyer, Edmond

    according to a velocity-jump process, and proliferating thanks to a reaction term of monostable typeFront propagation in a kinetic reaction-transport equation Emeric Bouin , Vincent Calvez wave solutions of a kinetic reaction- transport equation. The model describes particles moving

  6. Snapshot Day 10/17/14 Data (Salt Front RM 65.3)

    E-Print Network [OSTI]

    Lance, Veronica P.

    Snapshot Day 10/17/14 Data (Salt Front RM 65.3) RIVER MILE 53 Garrison Landing Park Cathy Bakker, Hudson Highlands Land Trust Kevin Keegan, Garrison Union Free School 7th graders 27 students, 6 adults 41 22 57 N ­ 73 36 93 W Location: Garrison Landing Park, Garrison, Putnam County, NY Area: Waterfront

  7. Continuous Planning With Winding Constraints Using Optimal Heuristic-Driven Front Propagation

    E-Print Network [OSTI]

    LaValle, Steven M.

    Continuous Planning With Winding Constraints Using Optimal Heuristic-Driven Front Propagation the winding-constrained optimal feedback navigation problem. Given the start and the goal positions and the winding con- straints, the solution to this problem is a feedback vector field such that, when integrated

  8. Physical model of back line-contact front-junction solar cells Andres Cuevas

    E-Print Network [OSTI]

    electron-collector region is made by thermal dif- fusion of phosphorus, and the localized metal contactsPhysical model of back line-contact front-junction solar cells Andres Cuevas Citation: J. Appl-junction solar cells Andres Cuevasa) Research School of Engineering, The Australian National University, Canberra

  9. Do Debris Flows Pose a Hazard to Mountain-Front Property in Metropolitan Phoenix, Arizona?

    E-Print Network [OSTI]

    Dorn, Ron

    Do Debris Flows Pose a Hazard to Mountain-Front Property in Metropolitan Phoenix, Arizona? Ronald I by growing suburbs of metropoli- tan Phoenix, Arizona, including on steep slopes above large single hazard in Phoenix and perhaps other grow- ing cities in the desert Southwest. Key Words: debris flow

  10. A Framework for Machine Vision based on Neuro-Mimetic Front End Processing and Clustering

    E-Print Network [OSTI]

    Madhow, Upamanyu

    A Framework for Machine Vision based on Neuro-Mimetic Front End Processing and Clustering Emre") convolutional nets [1], [2], [3], [4], which loosely mimic the natural hierarchy of visual processing. Neuro, including retinal ganglion cells (RGCs) and the lateral geniculate nucleus (LGN), along with the simple

  11. Polymer Motors: Pushing out the Front and Pulling up the Back

    E-Print Network [OSTI]

    Oster, George

    Polymer Motors: Pushing out the Front and Pulling up the Back Alex Mogilner1 and George Oster2 and disassembly of polymers. We review the mechanisms of pushing and pulling by actin and microtubule filaments and the organizational principles of actin networks. We show how these polymer force generators are used

  12. Ocean fronts in the Southern California Current System and their role in structuring zooplankton distributions, diel vertical migration, and size composition

    E-Print Network [OSTI]

    Powell, Jesse Russell

    California Current System. California Cooperative Oceanicsystem. Oceanic fronts, particularly within boundary currentCalifornia Current System. California Cooperative Oceanic

  13. Global morphology and physical relations between the stars, gas and dust in the disc and arms of M100

    E-Print Network [OSTI]

    J. H. Knapen; J. E. Beckman

    1996-07-04

    We study star formation processes in the disc of the weakly barred grand design spiral galaxy M100 (NGC 4321) from a variety of images tracing recent massive star formation, old and young stars, dust, and neutral hydrogen. Differences between arm and interarm regions are specifically studied by decomposing the images into arm and non-arm zones. We find from a comparison of the morphology in H$\\alpha$, HI and dust that while the first two are coincident over most of the disc, they are offset from the dust lanes especially along the inner parts of the spiral arms: a picture which is indicative of a density wave shock moving through the arms. HI is formed near the young massive stars as a result of photo-dissociation. From radial profiles we find that in the region of the star-forming spiral arms the exponential scale lengths for H$\\alpha$, blue and near-infrared light, and 21 cm radio continuum are equal within the fitting errors. The scale lengths for the interarm region are also equal for all these tracers, but the arm scale lengths are significantly longer. This points to a common origin of the profiles in star formation, with little or no influence from radial population gradients or dust in the disc of this galaxy. The longer arm scale lengths are equivalent to an outwardly increasing arm-interarm contrast. We argue that the radial profiles of radio continuum and HI, as well as CO, are also directly regulated by star formation, and discuss the possible implications of this result for the interpretation of observed CO intensities in and outside spiral arms. We discuss the radial atomic hydrogen profile in some detail. Its almost perfectly flat shape in the region of the star-forming spiral arms may be explained by photodissociation and recombination processes in the presence of a limited

  14. Method of fabricating conductive electrodes on the front and backside of a thin film structure

    DOE Patents [OSTI]

    Tabada, Phillipe J. (Roseville, CA); Tabada, legal representative, Melody (Roseville, CA); Pannu, Satinderpall S. (Pleasanton, CA)

    2011-05-22

    A method of fabricating a thin film device having conductive front and backside electrodes or contacts. Top-side cavities are first formed on a first dielectric layer, followed by the deposition of a metal layer on the first dielectric layer to fill the cavities. Defined metal structures are etched from the metal layer to include the cavity-filled metal, followed by depositing a second dielectric layer over the metal structures. Additional levels of defined metal structures may be formed in a similar manner with vias connecting metal structures between levels. After a final dielectric layer is deposited, a top surface of a metal structure of an uppermost metal layer is exposed through the final dielectric layer to form a front-side electrode, and a bottom surface of a cavity-filled portion of a metal structure of a lowermost metal layer is also exposed through the first dielectric layer to form a back-side electrode.

  15. SiPM and front-end electronics development for Cherenkov light detection

    E-Print Network [OSTI]

    Ambrosi, G; Bissaldi, E; Ferri, A; Giordano, F; Gola, A; Ionica, M; Paoletti, R; Piemonte, C; Paternoster, G; Simone, D; Vagelli, V; Zappala, G; Zorzi, N

    2015-01-01

    The Italian Institute of Nuclear Physics (INFN) is involved in the development of a demonstrator for a SiPM-based camera for the Cherenkov Telescope Array (CTA) experiment, with a pixel size of 6$\\times$6 mm$^2$. The camera houses about two thousands electronics channels and is both light and compact. In this framework, a R&D program for the development of SiPMs suitable for Cherenkov light detection (so called NUV SiPMs) is ongoing. Different photosensors have been produced at Fondazione Bruno Kessler (FBK), with different micro-cell dimensions and fill factors, in different geometrical arrangements. At the same time, INFN is developing front-end electronics based on the waveform sampling technique optimized for the new NUV SiPM. Measurements on 1$\\times$1 mm$^2$, 3$\\times$3 mm$^2$, and 6$\\times$6 mm$^2$ NUV SiPMs coupled to the front-end electronics are presented

  16. Superconformal Baryon-Meson Symmetry and Light-Front Holographic QCD

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Dosch, Hans Guenter; de Teramond, Guy F.; Brodsky, Stanley J.

    2015-04-10

    We construct an effective QCD light-front Hamiltonian for both mesons and baryons in the chiral limit based on the generalized supercharges of a superconformal graded algebra. The superconformal construction is shown to be equivalent to a semi-classical approximation to light-front QCD and its embedding in AdS space. The specific breaking of conformal invariance inside the graded algebra uniquely determines the effective confinement potential. The generalized supercharges connect the baryon and meson spectra to each other in a remarkable manner. In particular, the ?/b1 Regge trajectory is identified as the superpartner of the nucleon trajectory. However, the lowest-lying state on thismore »trajectory, the ?-meson is massless in the chiral limit and has no supersymmetric partner.« less

  17. Soil water content dependent wetting front characteristics in sands T.W.J. Bautersa

    E-Print Network [OSTI]

    Walter, M.Todd

    Soil water content dependent wetting front characteristics in sands T.W.J. Bautersa , D.A. Di 94305, USA Received 2 April 1999; accepted 13 August 1999 Abstract The initial soil water content into a 20/30 sand with initial volumetric water contents of 0, 0.005, 0.01, 0.015, 0.02, 0.03, 0.04 and 0

  18. Method and apparatus for generating radiation utilizing DC to AC conversion with a conductive front

    DOE Patents [OSTI]

    Dawson, John M. (Pacific Palisades, CA); Mori, Warren B. (Hermosa Beach, CA); Lai, Chih-Hsiang (So. Pasadena, CA); Katsouleas, Thomas C. (Malibu, CA)

    1998-01-01

    Method and apparatus for generating radiation of high power, variable duration and broad tunability over several orders of magnitude from a laser-ionized gas-filled capacitor array. The method and apparatus convert a DC electric field pattern into a coherent electromagnetic wave train when a relativistic ionization front passes between the capacitor plates. The frequency and duration of the radiation is controlled by the gas pressure and capacitor spacing.

  19. Clustering, fronts, and heat transfer in turbulent suspensions of heavy particles

    E-Print Network [OSTI]

    Bec, Jeremie; Krstulovic, Giorgio

    2014-01-01

    Heavy inertial particles transported by a turbulent flow are shown to concentrate in the regions where an advected passive scalar, such as temperature, displays very strong front-like discontinuities. This novel effect is responsible for extremely high levels of fluctuations for the passive field sampled by the particles that impacts the heat fluxes exchanged between the particles and the surrounding fluid. Instantaneous and averaged heat fluxes are shown to follow strongly intermittent statistics and anomalous scaling laws.

  20. Merging Cold Fronts in the Galaxy Pair NGC 7619 and NGC 7626

    E-Print Network [OSTI]

    S. W. Randall; C. Jones; R. Kraft; W. R. Forman; E. O'Sullivan

    2009-01-22

    We present results from {\\it Chandra} observations of the galaxy pair NGC 7619 and NGC 7626, the two dominant members of the Pegasus group. The X-ray images show a brightness edge associated with each galaxy, which we identify as merger cold fronts. The edges are sharp, and the axes of symmetry of the edges are roughly anti-parallel, suggesting that these galaxies are falling towards one another in the plane of the sky. The detection of merger cold fronts implies a merging subgroup scenario, since the alternative is that the galaxies are falling into a pre-existing $\\sim1$ keV halo without a dominant galaxy of its own, and such objects are not observed. We estimate the 3D velocities from the cold fronts and show that the velocity vectors are indeed most likely close to the plane of the sky, with a relative velocity of $\\sim1190\\kms$. The relative velocity is consistent with what is expected from the infall of two roughly equal mass subgroups whose total viral mass equals that of the Pegasus group. We conclude that the Pegasus cluster is currently forming from a major merger of two subgroups, dominated by NGC 7619 and NGC 7626. NGC 7626 contains a strong radio source, a core with two symmetric jets and radio lobes. Although we find no associated structure in the X-ray surface brightness map, the temperature map reveals a clump of cool gas just outside the southern lobe, presumably entrained by the lobe, and an extension of cooler gas into the lobe itself. The jet axis is parallel with the projected direction of motion of NGC 7626 (inferred from the symmetry axis of the merger cold front), and the southern leading jet is foreshortened as compared to the northern trailing one, possibly due to the additional ram pressure the forward jet encounters.

  1. Fast and slow magnetic deflagration fronts in Type I X-ray bursts

    E-Print Network [OSTI]

    Cavecchi, Yuri; Watts, Anna L; Braithwaite, Jonathan

    2015-01-01

    Type I X-ray bursts are produced by thermonuclear runaways that develop on accreting neutron stars. Once one location ignites, the flame propagates across the surface of the star. Flame propagation is fundamental in order to understand burst properties like rise time and burst oscillations. Previous work quantified the effects of rotation on the front, showing that the flame propagates as a deflagration and that the front strongly resembles a hurricane. However the effect of magnetic fields was not investigated, despite the fact that magnetic fields strong enough to have an effect on the propagating flame are expected to be present on many bursters. In this paper we show how the coupling between fluid layers introduced by an initially vertical magnetic field plays a decisive role in determining the character of the fronts that are responsible for the Type I bursts. In particular, on a star spinning at 450 Hz (typical among the bursters) we test seed magnetic fields of $10^{7} - 10^{10}$ G and find that for th...

  2. FBI Fingerprint Image Capture System High-Speed-Front-End throughput modeling

    SciTech Connect (OSTI)

    Rathke, P.M.

    1993-09-01

    The Federal Bureau of Investigation (FBI) has undertaken a major modernization effort called the Integrated Automated Fingerprint Identification System (IAFISS). This system will provide centralized identification services using automated fingerprint, subject descriptor, mugshot, and document processing. A high-speed Fingerprint Image Capture System (FICS) is under development as part of the IAFIS program. The FICS will capture digital and microfilm images of FBI fingerprint cards for input into a central database. One FICS design supports two front-end scanning subsystems, known as the High-Speed-Front-End (HSFE) and Low-Speed-Front-End, to supply image data to a common data processing subsystem. The production rate of the HSFE is critical to meeting the FBI`s fingerprint card processing schedule. A model of the HSFE has been developed to help identify the issues driving the production rate, assist in the development of component specifications, and guide the evolution of an operations plan. A description of the model development is given, the assumptions are presented, and some HSFE throughput analysis is performed.

  3. The New Front-End Electronics for the ATLAS Tile Calorimeter Phase 2 Upgrade

    E-Print Network [OSTI]

    Drake, Gary; The ATLAS collaboration

    2015-01-01

    We present the plans, design, and performance results to date ofor the new front-end electronics being developed for the Phase 2 Upgrade of the ATLAS Tile Calorimeter. The front-end electronics will be replaced to address the increase in beam energy and luminosity planned for the LHC around 2023, as well as to upgrade to faster, more modern components with higher radiation tolerance. The new electronics will operate dead-timelessly, pushing full data sets from each beam crossing to the data acquisition system that resides off-detector in the USA15 counting room. The new electronics contains five main parts: the front-end boards that connect directly to the photo-multiplier tubes; the Main Boards that digitize the data; the Daughter Boards that collect the data streams and contain the high-speed optical communication links for writing data to the data acquisition system; a programmable high voltage control system; and a new low-voltage power supply. There are different options for implementing these subcompone...

  4. Resource intensities of the front end of the nuclear fuel cycle

    SciTech Connect (OSTI)

    Schneider, E.; Phathanapirom, U.; Eggert, R.; Collins, J.

    2013-07-01

    This paper presents resource intensities, including direct and embodied energy consumption, land and water use, associated with the processes comprising the front end of the nuclear fuel cycle. These processes include uranium extraction, conversion, enrichment, fuel fabrication and depleted uranium de-conversion. To the extent feasible, these impacts are calculated based on data reported by operating facilities, with preference given to more recent data based on current technologies and regulations. All impacts are normalized per GWh of electricity produced. Uranium extraction is seen to be the most resource intensive front end process. Combined, the energy consumed by all front end processes is equal to less than 1% of the electricity produced by the uranium in a nuclear reactor. Land transformation and water withdrawals are calculated at 8.07 m{sup 2} /GWh(e) and 1.37x10{sup 5} l/GWh(e), respectively. Both are dominated by the requirements of uranium extraction, which accounts for over 70% of land use and nearly 90% of water use.

  5. Light-front representation of chiral dynamics in peripheral transverse densities

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Granados, Carlos G.; Weiss, Christian

    2015-07-31

    The nucleon's electromagnetic form factors are expressed in terms of the transverse densities of charge and magnetization at fixed light-front time. At peripheral transverse distances b = O(M_pi^{-1}) the densities are governed by chiral dynamics and can be calculated model-independently using chiral effective field theory (EFT). We represent the leading-order chiral EFT results for the peripheral transverse densities as overlap integrals of chiral light-front wave functions, describing the transition of the initial nucleon to soft pion-nucleon intermediate states and back. The new representation (a) explains the parametric order of the peripheral transverse densities; (b) establishes an inequality between the spin-independentmore »and -dependent densities; (c) exposes the role of pion orbital angular momentum in chiral dynamics; (d) reveals a large left-right asymmetry of the current in a transversely polarized nucleon and suggests a simple interpretation. The light-front representation enables a first-quantized, quantum-mechanical view of chiral dynamics that is fully relativistic and exactly equivalent to the second-quantized, field-theoretical formulation. It relates the charge and magnetization densities measured in low-energy elastic scattering to the generalized parton distributions probed in peripheral high-energy scattering processes. The method can be applied to nucleon form factors of other operators, e.g. the energy-momentum tensor.« less

  6. Light-front representation of chiral dynamics in peripheral transverse densities

    E-Print Network [OSTI]

    C. Granados; C. Weiss

    2015-03-16

    The nucleon's electromagnetic form factors are expressed in terms of the transverse densities of charge and magnetization at fixed light-front time. At peripheral transverse distances $b = O(M_\\pi^{-1})$ the densities are governed by chiral dynamics and can be calculated model-independently using chiral effective field theory (EFT). We represent the leading-order chiral EFT results for the peripheral transverse densities as overlap integrals of chiral light-front wave functions, describing the transition of the initial nucleon to soft pion-nucleon intermediate states and back. The new representation (a) explains the parametric order of the peripheral transverse densities; (b) establishes an inequality between the spin-independent and -dependent densities; (c) exposes the role of pion orbital angular momentum in chiral dynamics; (d) reveals a large left-right asymmetry of the current in a transversely polarized nucleon and suggests a simple interpretation. The light-front representation enables a first-quantized, quantum-mechanical view of chiral dynamics that is fully relativistic and exactly equivalent to the second-quantized, field-theoretical formulation. It relates the charge and magnetization densities measured in low-energy elastic scattering to the generalized parton distributions probed in peripheral high-energy scattering processes. The method can be applied to nucleon form factors of other operators, e.g. the energy-momentum tensor.

  7. An Eta-model output study of frontogenesis conditions favoring development of a troposphere-spanning front 

    E-Print Network [OSTI]

    Stewart, Jeffrey Paul

    1999-01-01

    the formation of a troposphere spanning front, tilting, confluent and shear deformation terms of the Petterssen and other applicable frontogenesis equations were evaluated utilizing numerical model output of the Eta model. The outcome of this study indicates...

  8. FPI (Islamic Defenders' Front): the Making of a Violent Islamist Movement in the New Democracy of Indonesia 

    E-Print Network [OSTI]

    Munajat

    2012-07-16

    The current study is aimed at investigating the puzzle of why FPI (Islamic Defenders' Front) has chosen to adopt violent strategies within the democratic context of Indonesia. Much of literature on social movements suggests ...

  9. 0011-9164/09/$ See front matter 2008 Elsevier B.V. All rights reserved Desalination 239 (2009) 1021

    E-Print Network [OSTI]

    2009-01-01

    0011-9164/09/$­ See front matter © 2008 Elsevier B.V. All rights reserved Desalination 239 (2009. / Desalination 239 (2009) 10­21 11 use as irrigation water, process water, or a source of potable water

  10. The Central American cold surge: an observational analysis of the deep southward penetration of North American cold fronts 

    E-Print Network [OSTI]

    Reding, Philip John

    1992-01-01

    THE CENTRAL AMERICAN COLD SURGE: AN OBSERVATIONAL ANALYSIS OF THE DEEP SOUTHWARD PENETRATION OF NORTH AMERICAN COLD FRONTS A Thesis by PHILIP JOHN REDING 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 December 1992 Major Subject: Meteorology THE CENTRAL AMERICAN COLD SURGE: AN OBSERVATIONAL ANALYSIS OF THE DEEP SOUTHWARD PENETRATION OF NORTH AMERICAN COLD FRONTS A Thesis by PHILIP...

  11. Unstructured grids in 3D and 4D for a time-dependent interface in front tracking with improved accuracy

    SciTech Connect (OSTI)

    Glimm, J.; Grove, J. W. (John W.); Li, X. L.; Li, Y. (Yingjie); Xu, Z. (Zhilang)

    2002-01-01

    Front tracking traces the dynamic evolution of an interface separating differnt materials or fluid components. In this paper, they describe three types of the grid generation methods used in the front tracking method. One is the unstructured surface grid. The second is a structured grid-based reconstruction method. The third is a time-space grid, also grid based, for a conservative tracking algorithm with improved accuracy.

  12. Satellite observations and numerical simulations of jet-front gravity waves over North America and North Atlantic Ocean 

    E-Print Network [OSTI]

    Zhang, Meng

    2008-10-10

    SIMULATIONS OF JET-FRONT GRAVITY WAVES OVER NORTH AMERICA AND NORTH ATLANTIC OCEAN A Thesis by MENG ZHANG 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 2008 Major Subject: Atmospheric Sciences SATELLITE OBSERVATIONS AND NUMERICAL SIMULATIONS OF JET-FRONT GRAVITY WAVES OVER NORTH AMERICA AND NORTH ATLANTIC OCEAN A Thesis by MENG ZHANG Submitted to the Office...

  13. [Front Matter

    E-Print Network [OSTI]

    2009-01-01

    bargaining agreement (CBA) on May 20, 2008, it spelled2 in favor of the current CBA were now opting out of it onlybonuses themselves, as well as the CBA, contain forfeiture

  14. [Front Matter

    E-Print Network [OSTI]

    2012-01-01

    agreed to in 2006 (the 2006 CBA). That night, nine currentallegedly violated the 2006 CBA, retired players fought forlawsuits and agreed to a new CBA (the 2011 CBA) without

  15. [Front Matter

    E-Print Network [OSTI]

    2007-01-01

    Calvert . The FBI in July 2006 beganor other motivations did the FBI have for suddenly beginningselective enforcement by the FBI in terms of which companies

  16. [Front Matter

    E-Print Network [OSTI]

    2008-01-01

    speech protection. Inside the FBI Inspections of Adult Movieconducted by the authors with FBI Supervisory Special AgentChuck Joyner at the FBI office in Los Angeles. Whereas the

  17. Front Matter

    E-Print Network [OSTI]

    2015-01-01

    UCLA Journal of Environmental Law and Policy is funded by:UCLA Journal of Environmental Law and Policy. All RightsUCLA Journal of Environmental Law and Policy is edited and

  18. Front Matter

    E-Print Network [OSTI]

    n/a, n/a

    2006-01-01

    by J. Shadid, USAlD, Mali \\'(IOm. 'U1 ufahamu-n. [Swahili]and will be moving back to Mali thereafter. "Umar Tall: The

  19. Section: Front

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantityBonneville Power AdministrationRobust, High-ThroughputUpcomingmagnetoresistanceand Governmentm D m r ecmswL, Attachment

  20. front cover

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantityBonneville Power AdministrationRobust,Field-effectWorkingLosThe 26th Annual Conference onDickAlThe30/03foalResolving9

  1. front cover

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantityBonneville Power AdministrationRobust,Field-effectWorkingLosThe 26th Annual Conference onDickAlThe30/03foalResolving9Preferred

  2. front cover

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantityBonneville Power AdministrationRobust,Field-effectWorkingLosThe 26th Annual Conference

  3. Front cover

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

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  4. The morphology of the Milky Way - II. Reconstructing CO maps from disc galaxies with live stellar distributions

    E-Print Network [OSTI]

    Pettitt, Alex R; Acreman, David M; Bate, Matthew R

    2015-01-01

    The arm structure of the Milky Way remains somewhat of an unknown, with observational studies hindered by our location within the Galactic disc. In the work presented here we use smoothed particle hydrodynamics (SPH) and radiative transfer to create synthetic longitude-velocity observations. Our aim is to reverse-engineer a top down map of the Galaxy by comparing synthetic longitude-velocity maps to those observed. We set up a system of N-body particles to represent the disc and bulge, allowing for dynamic creation of spiral features. Interstellar gas, and the molecular content, is evolved alongside the stellar system. A 3D-radiative transfer code is then used to compare the models to observational data. The resulting models display arm features that are a good reproduction of many of the observed emission structures of the Milky Way. These arms however are dynamic and transient, allowing for a wide range of morphologies not possible with standard density wave theory. The best fitting models are a much better...

  5. Percutaneous Transcatheter One-Step Mechanical Aortic Disc Valve Prosthesis Implantation: A Preliminary Feasibility Study in Swine

    SciTech Connect (OSTI)

    Sochman, Jan [Institute for Clinical and Experimental Medicine, Intensive Care Unit, Clinic of Cardiology (Czech Republic)], E-mail: jan.sochman@medicon.cz; Peregrin, Jan H.; Rocek, Miloslav [Institute for Clinical and Experimental Medicine, Department of Diagnostic and Interventional Radiology (Czech Republic); Timmermans, Hans A.; Pavcnik, Dusan; Roesch, Josef [Oregon Health and Sciences University, Dotter Interventional Institute (United States)

    2006-02-15

    Purpose. To evaluate the feasibility of one-step implantation of a new type of stent-based mechanical aortic disc valve prosthesis (MADVP) above and across the native aortic valve and its short-term function in swine with both functional and dysfunctional native valves. Methods. The MADVP consisted of a folding disc valve made of silicone elastomer attached to either a nitinol Z-stent (Z model) or a nitinol cross-braided stent (SX model). Implantation of 10 MADVPs (6 Z and 4 SX models) was attempted in 10 swine: 4 (2 Z and 2 SX models) with a functional native valve and 6 (4 Z and 2 SX models) with aortic regurgitation induced either by intentional valve injury or by MADVP placement across the native valve. MADVP function was observed for up to 3 hr after implantation. Results. MADVP implantation was successful in 9 swine. One animal died of induced massive regurgitation prior to implantation. Four MADVPs implanted above functioning native valves exhibited good function. In 5 swine with regurgitation, MADVP implantation corrected the induced native valve dysfunction and the device's continuous good function was observed in 4 animals. One MADVP (SX model) placed across native valve gradually migrated into the left ventricle. Conclusion. The tested MADVP can be implanted above and across the native valve in a one-step procedure and can replace the function of the regurgitating native valve. Further technical development and testing are warranted, preferably with a manufactured MADVP.

  6. Quantifying stellar radial migration in a N-body simulation: blurring, churning, and the outer regions of galaxy discs

    E-Print Network [OSTI]

    Halle, A; Haywood, M; Combes, F

    2015-01-01

    Radial stellar migration in galactic discs has drawn a lot of attention in studies of galactic dynamics and chemical evolution, but remains a dynamical phenomenon that needs to be fully quantified. In this work, using a Tree-SPH simulation of a Sb-type disc galaxy, we quantify the effects of blurring (epicyclic excursions) and churning (change of guiding radius). We quantify migration (either blurring or churning) both in terms of flux (the number of migrators passing at a given radius), and by estimating the population of migrators at a given radius at the end of the simulation compared to non-migrators, but also by giving the distance over which the migration is effective at all radii. We confirm that the corotation of the bar is the main source of migrators by churning in a bar-dominated galaxy, its intensity being directly linked to the episode of strong bar, in the first 1-3 Gyr of the simulation. We show that within the OLR, migration is strongly dominated by churning, while blurring gains progressively...

  7. Intermittent Peel Front Dynamics and the Crackling Noise in an Adhesive Tape

    E-Print Network [OSTI]

    Jagadish Kumar; Rumi De; G. Ananthakrishna

    2008-12-01

    We report a comprehensive investigation of a model for peeling of an adhesive tape along with a nonlinear time series analysis of experimental acoustic emission signals in an effort to understand the origin of intermittent peeling of an adhesive tape and its connection to acoustic emission. The model represents the acoustic energy dissipated in terms of Rayleigh dissipation functional that depends on the local strain rate. We show that the nature of the peel front exhibits rich spatiotemporal patterns ranging from smooth, rugged and stuck-peeled configurations that depend on three parameters, namely, the ratio of inertial time scale of the tape mass to that of the roller, the dissipation coefficient and the pull velocity. The stuck-peeled configurations are reminiscent of fibrillar peel front patterns observed in experiments. We show that while the intermittent peeling is controlled by the peel force function, the model acoustic energy dissipated depends on the nature of the peel front and its dynamical evolution. Even though the acoustic energy is a fully dynamical quantity, it can be quite noisy for a certain set of parameter values suggesting the deterministic origin of acoustic emission in experiments. To verify this suggestion, we have carried out a dynamical analysis of experimental acoustic emission time series for a wide range of traction velocities. Our analysis shows an unambiguous presence of chaotic dynamics within a subinterval of pull speeds within the intermittent regime. Time series analysis of the model acoustic energy signals is also found to be chaotic within a subinterval of pull speeds.

  8. Resonant Coherent Excitation of Fast Hydrogen Atoms in Front of a LiF(001) Surface

    SciTech Connect (OSTI)

    Auth, C.; Mertens, A.; Winter, H.; Borisov, A.G.; Garcia de Abajo, F.J.

    1997-12-01

    We have scattered protons and hydrogen atoms with energies of some keV from a LiF(001) surface under a grazing angle of incidence. From the intensity of Lyman-{alpha} radiation (transition from n=2 to n=1, {lambda}=121.6 nm ) as a function of projectile energy for different azimuthal orientations of the crystal surface, we find clear evidence for a resonant coherent excitation of n=2 states of hydrogen atoms in the oscillating electric field in front of the insulator surface. {copyright} {ital 1997} {ital The American Physical Society}

  9. On the ion front of a plasma expanding into a vacuum

    SciTech Connect (OSTI)

    Allen, J. E.; University College, Oxford, Oxford OX1 4BH ; Perego, M.

    2014-03-15

    Calculations are reported on the expansion of a plasma into a vacuum, using a model of cold ions and Boltzmann electrons. The initial distribution of the ions at the edge of the plasma greatly affects the subsequent expansion. An initial abrupt drop of ion density leads to an expansion in which the abrupt drop is maintained. A finite slope, however, leads to the formation of a peak of ion density at the ion front. The subsequent behaviour may lead to wave breaking and the formation of multi-valued ion velocity distributions.

  10. Medium Corrections to the Nucleon Electroweak Observables in a Light-Front Quark Model

    SciTech Connect (OSTI)

    Araujo, W.R.B. de; Suisso, E.F.; Batista, E.F.; Carlson, B.V.; Frederico, T. [Dep. de Fisica, Instituto Tecnologico de Aeronautica, Centro Tecnico Aeroespacial, 12.228-900 Sao Jose dos Campos, Sao Paulo (Brazil)

    2004-12-02

    We study the nuclear medium effects on the proton electromagnetic form factor ratio GEp/GMp within a light-front constituent quark model with different quark spin coupling schemes and momentum components of the wave functions. We compute only effects from the quark and nucleon in-medium masses. The effective masses are obtained from a relativistic {sigma} - {omega} self-consistent mean-field approximation of the nuclear matter within a quark-meson coupling model. Our calculation describes qualitatively the recent experimental data.

  11. MERGING COLD FRONTS IN THE GALAXY PAIR NGC 7619 AND NGC 7626

    SciTech Connect (OSTI)

    Randall, S. W.; Jones, C.; Kraft, R.; Forman, W. R.; O'Sullivan, E.

    2009-05-10

    We present results from Chandra observations of the galaxy pair NGC 7619 and NGC 7626, the two dominant members of the Pegasus group. The X-ray images show a brightness edge associated with each galaxy, which we identify as merger cold fronts. The edges are sharp, and the axes of symmetry of the edges are roughly antiparallel, suggesting that these galaxies are falling toward one another in the plane of the sky. The detection of merger cold fronts in each of the two dominant member galaxies implies a merging subgroup scenario, since the alternative is that the galaxies are falling into a preexisting {approx}1 keV halo without a dominant galaxy of its own, and such objects are not observed. We estimate the three-dimensional velocities from the cold fronts and, using the observed radial velocities of the galaxies, show that the velocity vectors are indeed most likely close to the plane of the sky, with a relative velocity of {approx}1190 km s{sup -1}. The relative velocity is consistent with what is expected from the infall of two roughly equal mass subgroups whose total viral mass equals that of the Pegasus group. We conclude that the Pegasus cluster is most likely currently forming from a major merger of two subgroups, dominated by NGC 7619 and NGC 7626. NGC 7626 contains a strong radio source, consisting of a core with two symmetric jets, and radio lobes. Although we find no associated structure in the X-ray surface brightness map, the temperature map reveals a clump of cool gas just outside the southern lobe, presumably entrained by the lobe, and possibly an extension of cooler gas into the lobe itself. The jet axis is parallel with the projected direction of motion of NGC 7626 (inferred from the symmetry axis of the merger cold front), and the southern leading jet is foreshortened as compared to the northern trailing one, possibly due to the additional ram pressure encountered by the forward jet.

  12. Meso and microscale features of the lower portion of cold fronts 

    E-Print Network [OSTI]

    Beniura, Hideo

    1962-01-01

    to Fig. 1 (After Petterssen, 1961). Figure 3. Figure 4. Advancing mass of cold air (After Prandtl, 19S2), Tower network and its location relative to Dallas and Amon Carter Field. Figure 5. The sectional surface chart for 1200 GMT, 22 November 1961... the ground will usually have an upward component. Bergeron mentions the figure of 1 to 4 km above the sur'face as the lower edge of the descending air, In 1910 Schmidt studied a laboratory model of a cold front in which the analog between cold and wsxm...

  13. Segregation of a Keplerian disc and sub-Keplerian halo from a Transonic flow around a Black Hole by Viscosity and Cooling processes

    E-Print Network [OSTI]

    Giri, Kinsuk; Chakrabarti, Sandip K

    2015-01-01

    A black hole accretion is necessarily transonic. In presence of sufficiently high viscosity and cooling effects, a low-angular momentum transonic flow can become a standard Keplerian disc except close to the where hole where it must pass through the inner sonic point. However, if the viscosity is not high everywhere and cooling is not efficient everywhere, the flow cannot completely become a Keplerian disc. In this paper, we show results of rigorous numerical simulations of a transonic flow having vertically varying viscosity parameter (being highest on the equatorial plane) and optical depth dependent cooling processes to show that the flow indeed segregates into two distinct components as it approaches a black hole. The component on the equatorial plane has properties of a standard Keplerian disc, though the flow is not truncated at the inner- most stable circular orbit. This component extends till the horizon as a sub-Keplerian flow. This standard disc is found to be surrounded by a hot, low angular moment...

  14. FELIX: a High-Throughput Network Approach for Interfacing to Front End Electronics for ATLAS Upgrades

    E-Print Network [OSTI]

    Anderson, John Thomas; The ATLAS collaboration; Boterenbrood, Hendrik; Chen, Hucheng; Chen, Kai; Drake, Gary; Francis, David; Gorini, Benedetto; Lanni, Francesco; Lehmann Miotto, Giovanna; Levinson, Lorne; Narevicius, Julia; Plessl, Christian; Roich, Alexander; Ryu, Soo; Schreuder, Frans Philip; Schumacher, Jorn; Vandelli, Wainer; Vermeulen, Jos; Zhang, Jinlong

    2015-01-01

    The ATLAS experiment at CERN is planning full deployment of a new unified optical link technology for connecting detector front end electronics on the timescale of the LHC Run 4 (2025). It is estimated that roughly 8000 GBT (GigaBit Transceiver) links, with transfer rates up to 10.24~Gbps, will replace existing links used for readout, detector control and distribution of timing and trigger information. A new class of devices will be needed to interface many GBT links to the rest of the trigger, data-acquisition and detector control systems. In this paper FELIX (Front End LInk eXchange) is presented, a PC-based device to route data from and to multiple GBT links via a high-performance general purpose network capable of a total throughput up to O(20 Tbps). FELIX implies architectural changes to the ATLAS data acquisition system, such as the use of industry standard COTS components early in the DAQ chain. Additionally the design and implementation of a FELIX demonstration platform is presented, and hardware and ...

  15. Adapting wave-front algorithms to efficiently utilize systems with deep communication hierarchies

    SciTech Connect (OSTI)

    Kerbyson, Darren J; Lang, Michael; Pakin, Scott

    2009-01-01

    Large-scale systems increasingly exhibit a differential between intra-chip and inter-chip communication performance. Processor-cores on the same socket are able to communicate at lower latencies, and with higher bandwidths, than cores on different sockets either within the same node or between nodes. A key challenge is to efficiently use this communication hierarchy and hence optimize performance. We consider here the class of applications that contain wave-front processing. In these applications data can only be processed after their upstream neighbors have been processed. Similar dependencies result between processors in which communication is required to pass boundary data downstream and whose cost is typically impacted by the slowest communication channel in use. In this work we develop a novel hierarchical wave-front approach that reduces the use of slower communications in the hierarchy but at the cost of additional computation and higher use of on-chip communications. This tradeoff is explored using a performance model and an implementation on the Petascale Roadrunner system demonstrates a 27% performance improvement at full system-scale on a kernel application. The approach is generally applicable to large-scale multi-core and accelerated systems where a differential in system communication performance exists.

  16. Interferometric adaptive optics for high power laser pointing, wave-front control and phasing

    SciTech Connect (OSTI)

    Baker, K L; Stappaerts, E A; Homoelle, D C; Henesian, M A; Bliss, E S; Siders, C W; Barty, C J

    2009-01-21

    Implementing the capability to perform fast ignition experiments, as well as, radiography experiments on the National Ignition Facility (NIF) places stringent requirements on the control of each of the beam's pointing and overall wavefront quality. One quad of the NIF beams, 4 beam pairs, will be utilized for these experiments and hydrodynamic and particle-in-cell simulations indicate that for the fast ignition experiments, these beams will be required to deliver 50% (4.0 kJ) of their total energy (7.96 kJ) within a 40 {micro}m diameter spot at the end of a fast ignition cone target. This requirement implies a stringent pointing and overall phase conjugation error budget on the adaptive optics system used to correct these beam lines. The overall encircled energy requirement is more readily met by phasing of the beams in pairs but still requires high Strehl ratios, Sr, and rms tip/tilt errors of approximately one {micro}rad. To accomplish this task we have designed an interferometric adaptive optics system capable of beam pointing, high Strehl ratio and beam phasing with a single pixilated MEMS deformable mirror and interferometric wave-front sensor. We present the design of a testbed used to evaluate the performance of this wave-front sensor below along with simulations of its expected performance level.

  17. Top Ten Reasons for DEOX as a Front End to Pyroprocessing

    SciTech Connect (OSTI)

    B.R. Westphal; K.J. Bateman; S.D. Herrmann

    2007-11-01

    A front end step is being considered to augment chopping during the treatment of spent oxide fuel by pyroprocessing. The front end step, termed DEOX for its emphasis on decladding via oxidation, employs high temperatures to promote the oxidation of UO2 to U3O8 via an oxygen carrier gas. During oxidation, the spent fuel experiences a 30% increase in lattice structure volume resulting in the separation of fuel from cladding with a reduced particle size. A potential added benefit of DEOX is the removal of fission products, either via direct release from the broken fuel structure or via oxidation and volatilization by the high temperature process. Fuel element chopping is the baseline operation to prepare spent oxide fuel for an electrolytic reduction step. Typical chopping lengths range from 1 to 5 mm for both individual elements and entire assemblies. During electrolytic reduction, uranium oxide is reduced to metallic uranium via a lithium molten salt. An electrorefining step is then performed to separate a majority of the fission products from the recoverable uranium. Although DEOX is based on a low temperature oxidation cycle near 500oC, additional conditions have been tested to distinguish their effects on the process.[1] Both oxygen and air have been utilized during the oxidation portion followed by vacuum conditions to temperatures as high as 1200oC. In addition, the effects of cladding on fission product removal have also been investigated with released fuel to temperatures greater than 500oC.

  18. The Majorana low-noise low-background front-end electronics

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Abgrall, N.; Aguayo, E.; Avignone, III, F. T.; Barabash, A. S.; Bertrand, F. E.; Boswell, M.; Brudanin, V.; Busch, M.; Byram, D.; Caldwell, A. S.; et al

    2015-03-24

    The Majorana Demonstrator will search for the neutrinoless double beta decay (??(0?)) of the isotope ??Ge with a mixed array of enriched and natural germanium detectors. In view of the next generation of tonne-scale germanium-based ??(0?)-decay searches, a major goal of the Majorana Demonstrator is to demonstrate a path forward to achieving a background rate at or below 1 cnt/(ROI-t-y) in the 4 keV region of interest (ROI) around the 2039-keV Q-value of the ??Ge ??(0?)-decay. Such a requirement on the background level significantly constrains the design of the readout electronics, which is further driven by noise and energy resolutionmore »performances. We present here the low-noise low-background front-end electronics developed for the low-capacitance p-type point contact (P-PC) germanium detectors of the Majorana Demonstrator. This resistive-feedback front-end, specifically designed to have low mass, is fabricated on a radioassayed fused-silica substrate where the feedback resistor consists of a sputtered thin film of high purity amorphous germanium and the feedback capacitor is based on the capacitance between gold conductive traces.« less

  19. The Higgs oscillator on the hyperbolic plane and Light-Front Holography

    E-Print Network [OSTI]

    A. Pallares-Rivera; M. Kirchbach

    2014-11-19

    The Light Front Holographic (LFH) wave equation, which is the conformal scalar equation on the plane, is revisited from the perspective of the supersymmetric quantum mechanics, and attention is drawn to the fact that it naturally emerges in the small hyperbolic angle approximation to the "curved" Higgs oscillator on the hyperbolic plane, i.e. on the upper part of the two-dimensional hyperboloid of two sheets, a space of constant negative curvature. Such occurs because the particle dynamics under consideration reduces to the one dimensional Schr\\"odinger equation with the second hyperbolic P\\"oschl-Teller potential, whose flat-space (small-angle) limit reduces to the conformally invariant inverse square distance plus harmonic oscillator interaction, on which LFH is based. In consequence, energies and wave functions of the LFH spectrum can be approached by the solutions of the Higgs oscillator on the hyperbolic plane in employing its curvature and the potential strength as fitting parameters. Also the proton electric charge form factor is well reproduced within this scheme by means of a Fourier-Helgason hyperbolic wave transform of the charge density. In conclusion, in the small angle approximation, the Higgs oscillator on the hyperbolic plane is demonstrated to satisfactory parallel essential outcomes of the Light Front Holographic QCD. The findings are suggestive of associating the hyperboloid curvature of the with a second scale in LFH, which then could be employed in the definition of a chemical potential.

  20. Symmetric multivariate polynomials as a basis for three-boson light-front wave functions

    E-Print Network [OSTI]

    Sophia S. Chabysheva; Blair Elliott; John R. Hiller

    2013-07-18

    We develop a polynomial basis to be used in numerical calculations of light-front Fock-space wave functions. Such wave functions typically depend on longitudinal momentum fractions that sum to unity. For three particles, this constraint limits the two remaining independent momentum fractions to a triangle, for which the three momentum fractions act as barycentric coordinates. For three identical bosons, the wave function must be symmetric with respect to all three momentum fractions. Therefore, as a basis, we construct polynomials in two variables on a triangle that are symmetric with respect to the interchange of any two barycentric coordinates. We find that, through the fifth order, the polynomial is unique at each order, and, in general, these polynomials can be constructed from products of powers of the second and third-order polynomials. The use of such a basis is illustrated in a calculation of a light-front wave function in two-dimensional phi^4 theory; the polynomial basis performs much better than the plane-wave basis used in discrete light-cone quantization.

  1. Front-end electronics and readout system for the ILD TPC

    E-Print Network [OSTI]

    Hedberg, V; Lundberg, B; Mjörnmark, U; Oskarsson, A; Österman, L; De Lentdecker, G; Yang, Y; Zhang, F

    2015-01-01

    A high resolution TPC is the main option for a central tracking detector at the future International Linear Collider (ILC). It is planned that the MPGD (Micro Pattern Gas Detector) technology will be used for the readout. A Large Prototype TPC at DESY has been used to test the performance of MPGDs in an electron beam of energies up to 6 GeV. The first step in the technology development was to demonstrate that the MPGDs are able to achieve the necessary performance set by the goals of ILC. For this ’proof of principle’ phase, the ALTRO front-end electronics from the ALICE TPC was used, modified to adapt to MPGD readout. The proof of principle has been verified and at present further improvement of the MPGD technology is going on, using the same readout electronics. The next step is the ’feasibility phase’, which aims at producing front-end electronics comparable in size (few mm2) to the readout pads of the TPC. This development work is based on the succeeding SALTRO16 chip, which combines the analogue ...

  2. The Majorana low-noise low-background front-end electronics

    SciTech Connect (OSTI)

    Abgrall, N. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Aguayo, E. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Avignone, III, F. T. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Univ. of South Carolina, Columbia, SC (United States); Barabash, A. S. [Institute for Theoretical and Experiemental Physics, Moscow (Russia); Bertrand, F. E. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Boswell, M. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Brudanin, V. [Joint Institute for Nuclear Research, Durham, NC (United States); Busch, M. [Duke Univ., Durham, NC (United States); Triangle Univ. Nuclear Lab., Durham, NC (United States); Byram, D. [Univ. of South Dakota, Vermillion, SD (United States); Caldwell, A. S. [South Dakota School of Mines and Technology, Rapid City, SD (United States); Chan, Y. -D. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Christofferson, C. D. [South Dakota School of Mines and Technology, Rapid City, SD (United States); Combs, D. C. [North Carolina State Univ., Raleigh, NC (United States); Triangle Univ. Nuclear Lab., Durham, NC (United States); Cuesta, C. [Univ. of Washington, Seattle, WA (United States); Detwiler, J. A. [Univ. of Washington, Seattle, WA (United States); Doe, P. J. [Univ. of Washington, Seattle, WA (United States); Efremenko, Yu. [Univ. of Tennessee, Knoxville, TN (United States); Egorov, V. [Joint Institute for Nuclear Research, Durham, NC (United States); Ejiri, H. [Osaka Univ., Osaka (Japan); Elliott, S. R. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Fast, J. E. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Finnerty, P. [Univ. of North Carolina, Chapel Hill, NC (United States); Triangle Univ. Nuclear Lab., Durham, NC (United States); Fraenkle, F. M. [Univ. of North Carolina, Chapel Hill, NC (United States); Triangle Univ. Nuclear Lab., Durham, NC (United States); Galindo-Uribarri, A. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Giovanetti, G. K. [Univ. of North Carolina, Chapel Hill, NC (United States); Triangle Univ. Nuclear Lab., Durham, NC (United States); Goett, J. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Green, M. P. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Gruszko, J. [Univ. of Washington, Seattle, WA (United States); Guiseppe, V. E. [Univ. of South Carolina, Columbia, SC (United States); Gusev, K. [Joint Institute for Nuclear Research, Durham, NC (United States); Hallin, A. L. [Univ. of Alberta, Edmonton, AB (Canada); Hazama, R. [Osaka Univ., Osaka (Japan); Hegai, A. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); North Carolina State Univ., Raleigh, NC (United States); Henning, R. [Univ. of North Carolina, Chapel Hill, NC (United States); Triangle Univ. Nuclear Lab., Durham, NC (United States); Hoppe, E. W. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Howard, S. [South Dakota School of Mines and Technology, Rapid City, SD (United States); Howe, M. A. [Univ. of North Carolina, Chapel Hill, NC (United States); Triangle Univ. Nuclear Lab., Durham, NC (United States); Keeter, K. J. [Black Hills State Univ., Spearfish, SD (United States); Kidd, M. F. [Tennessee Tech Univ., Cookeville, TN (United States); Kochetov, O. [Joint Institute for Nuclear Research, Durham, NC (United States); Konovalov, S. I. [Institute for Theoretical and Experiemental Physics, Moscow (Russia); Kouzes, R. T. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); LaFerriere, B. D. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Leon, J. [Univ. of Washington, Seattle, WA (United States); Leviner, L. E. [North Carolina State Univ., Raleigh, NC (United States); Triangle Univ. Nuclear Lab., Durham, NC (United States); Loach, J. C. [Shanghai Jiao Tong Univ., Shanghai (China); MacMullin, J. [Univ. of North Carolina, Chapel Hill, NC (United States); Triangle Univ. Nuclear Lab., Durham, NC (United States)

    2015-01-01

    The Majorana Demonstrator will search for the neutrinoless double beta decay (??(0?)) of the isotope ??Ge with a mixed array of enriched and natural germanium detectors. In view of the next generation of tonne-scale germanium-based ??(0?)-decay searches, a major goal of the Majorana Demonstrator is to demonstrate a path forward to achieving a background rate at or below 1 cnt/(ROI-t-y) in the 4 keV region of interest (ROI) around the 2039-keV Q-value of the ??Ge ??(0?)-decay. Such a requirement on the background level significantly constrains the design of the readout electronics, which is further driven by noise and energy resolution performances. We present here the low-noise low-background front-end electronics developed for the low-capacitance p-type point contact (P-PC) germanium detectors of the Majorana Demonstrator. This resistive-feedback front-end, specifically designed to have low mass, is fabricated on a radioassayed fused-silica substrate where the feedback resistor consists of a sputtered thin film of high purity amorphous germanium and the feedback capacitor is based on the capacitance between gold conductive traces.

  3. Evaluation of a front-end ASIC for the readout of PMTs in large dynamic range

    E-Print Network [OSTI]

    Wu, Weihao; Liang, Yu; Yu, Li; Liu, Jianfeng; Liu, Shubin; An, Qi

    2015-01-01

    The Large High Altitude Air Shower Observatory (LHAASO) project has been proposed for the survey and study of cosmic rays. In the LHAASO project, the Water Cherenkov Detector Array (WCDA) is one of major detectors for searching gamma ray sources. A Charge-to-Time Convertor (QTC) ASIC (Application Specification Integrated Circuit) fabricated in Global Foundry 0.35 {\\mu}m CMOS technology, has been developed for readout of Photomultiplier Tubes (PMTs) in the WCDA. This paper focuses on the evaluation of this front-end readout ASIC performance. Test results indicate that the time resolution is better than 400 ps and the charge resolution is better than 1% with large input signals and remains better than 15% @ 1 Photo Electron (P.E.), both beyond the application requirement. Moreover, this ASIC has a weak ambient temperature dependence, low input rate dependence and high channel-to-channel isolation.

  4. Development of a transonic front stage of an axial flow compressor for industrial gas turbines

    SciTech Connect (OSTI)

    Katoh, Y.; Ishii, H.; Tsuda, Y.; Yanagida, M. . Mechanical Engineering Research Lab.); Kashiwabara, Y. . Dept. of Mechanical Systems Engineering)

    1994-10-01

    This paper describes the aerodynamic blade design of a highly loaded three-stage compressor, which is a model compressor for the front stage of an industrial gas turbine. Test results are presented that confirm design performance. Some surge and rotating stall measurement results are also discussed. The first stator blade in this test compressor operates in the high subsonic range at the inlet. To reduce the pressure loss due to blade surface shock waves, a shock-free airfoil is designed to replace the first stator blade in an NACA-65 airfoil in a three-stage compressor. Comparison of the performance of both blades shows that the shock-free airfoil blade reduces pressure loss. This paper also presents some experimental results for MCA (multicircular arc) airfoils, which are used for first rotor blades.

  5. Review of input stages used in front end electronics for particle detectors

    E-Print Network [OSTI]

    Kaplon, J

    2015-01-01

    In this paper we present noise analysis of the input stages most commonly used in front end electronics for particle detectors. Analysis shows the calculation of the input referenced noise related to the active devices. It identifies the type, parallel or series, of the equivalent noise sources related to the input transistors, which is the important input for the further choice of the signal processing method. Moreover we calculate the input impedance of amplifiers employed in applications where the particle detector is connected to readout electronics by means of transmission line. We present schematics, small signal models,a complete set of equations, and results of the major steps of calculations for all discussed circuits.

  6. The Analog Front-end Prototype Electronics Designed for LHAASO WCDA

    E-Print Network [OSTI]

    Cong Ma; Lei Zhao; Yu-Xiang Guo; Jian-Feng Liu; Shu-Bin Liu; Qi An

    2015-04-22

    In the readout electronics of the Water Cerenkov Detector Array (WCDA) in the Large High Altitude Air Shower Observatory (LHAASO) experiment, both high-resolution charge and time measurement are required over a dynamic range from 1 photoelectron (P.E.) to 4000 P.E. The Analog Front-end (AFE) circuit is one of the crucial parts in the whole readout electronics. We designed and optimized a prototype of the AFE through parameter calculation and circuit simulation, and conducted initial electronics tests on this prototype to evaluate its performance. Test results indicate that the charge resolution is better than 1% @ 4000 P.E. and remains better than 10% @ 1 P.E., and the time resolution is better than 0.5 ns RMS, which is better than application requirement.

  7. The Analog Front-end Prototype Electronics Designed for LHAASO WCDA

    E-Print Network [OSTI]

    Ma, Cong; Guo, Yu-Xiang; Liu, Jian-Feng; Liu, Shu-Bin; An, Qi

    2015-01-01

    In the readout electronics of the Water Cerenkov Detector Array (WCDA) in the Large High Altitude Air Shower Observatory (LHAASO) experiment, both high-resolution charge and time measurement are required over a dynamic range from 1 photoelectron (P.E.) to 4000 P.E. The Analog Front-end (AFE) circuit is one of the crucial parts in the whole readout electronics. We designed and optimized a prototype of the AFE through parameter calculation and circuit simulation, and conducted initial electronics tests on this prototype to evaluate its performance. Test results indicate that the charge resolution is better than 1% @ 4000 P.E. and remains better than 10% @ 1 P.E., and the time resolution is better than 0.5 ns RMS, which is better than application requirement.

  8. Hydrodynamics of phase transition fronts and the speed of sound in the plasma

    E-Print Network [OSTI]

    Leonardo Leitao; Ariel Megevand

    2015-03-06

    The growth of bubbles in cosmological first-order phase transitions involves nontrivial hydrodynamics. For that reason, the study of the propagation of phase transition fronts often requires several approximations. A frequently used approximation consists in describing the two phases as being composed only of radiation and vacuum energy (the so-called bag equation of state). We show that, in realistic models, the speed of sound in the low-temperature phase is generally smaller than that of radiation, and we study the hydrodynamics in such a situation. We find in particular that a new kind of hydrodynamical solution may be possible, which does not arise in the bag model. We obtain analytic results for the efficiency of the transfer of latent heat to bulk motions of the plasma, as a function of the speed of sound in each phase.

  9. Finite-time barriers to front propagation in two-dimensional fluid flows

    E-Print Network [OSTI]

    Mahoney, John R

    2015-01-01

    Recent theoretical and experimental investigations have demonstrated the role of certain invariant manifolds, termed burning invariant manifolds (BIMs), as one-way dynamical barriers to reaction fronts propagating within a flowing fluid. These barriers form one-dimensional curves in a two-dimensional fluid flow. In prior studies, the fluid velocity field was required to be either time-independent or time-periodic. In the present study, we develop an approach to identify prominent one-way barriers based only on fluid velocity data over a finite time interval, which may have arbitrary time-dependence. We call such a barrier a burning Lagrangian coherent structure (bLCS) in analogy to Lagrangian coherent structures (LCSs) commonly used in passive advection. Our approach is based on the variational formulation of LCSs using curves of stationary "Lagrangian shear", introduced by Farazmand, Blazevski, and Haller [Physica D 278-279, 44 (2014)] in the context of passive advection. We numerically validate our techniqu...

  10. Evaluation of a front-end ASIC for the readout of PMTs in large dynamic range

    E-Print Network [OSTI]

    Weihao Wu; Lei Zhao; Yu Liang; Li Yu; Jianfeng Liu; Shubin Liu; Qi An

    2015-02-05

    The Large High Altitude Air Shower Observatory (LHAASO) project has been proposed for the survey and study of cosmic rays. In the LHAASO project, the Water Cherenkov Detector Array (WCDA) is one of major detectors for searching gamma ray sources. A Charge-to-Time Convertor (QTC) ASIC (Application Specification Integrated Circuit) fabricated in Global Foundry 0.35 {\\mu}m CMOS technology, has been developed for readout of Photomultiplier Tubes (PMTs) in the WCDA. This paper focuses on the evaluation of this front-end readout ASIC performance. Test results indicate that the time resolution is better than 400 ps and the charge resolution is better than 1% with large input signals and remains better than 15% @ 1 Photo Electron (P.E.), both beyond the application requirement. Moreover, this ASIC has a weak ambient temperature dependence, low input rate dependence and high channel-to-channel isolation.

  11. Measures of the environmental footprint of the front end of the nuclear fuel cycle

    SciTech Connect (OSTI)

    E. Schneider; B. Carlsen; E. Tavrides; C. van der Hoeven; U. Phathanapirom

    2013-11-01

    Previous estimates of environmental impacts associated with the front end of the nuclear fuel cycle (FEFC) have focused primarily on energy consumption and CO2 emissions. Results have varied widely. This work builds upon reports from operating facilities and other primary data sources to build a database of front end environmental impacts. This work also addresses land transformation and water withdrawals associated with the processes of the FEFC. These processes include uranium extraction, conversion, enrichment, fuel fabrication, depleted uranium disposition, and transportation. To allow summing the impacts across processes, all impacts were normalized per tonne of natural uranium mined as well as per MWh(e) of electricity produced, a more conventional unit for measuring environmental impacts that facilitates comparison with other studies. This conversion was based on mass balances and process efficiencies associated with the current once-through LWR fuel cycle. Total energy input is calculated at 8.7 x 10- 3 GJ(e)/MWh(e) of electricity and 5.9 x 10- 3 GJ(t)/MWh(e) of thermal energy. It is dominated by the energy required for uranium extraction, conversion to fluoride compound for subsequent enrichment, and enrichment. An estimate of the carbon footprint is made from the direct energy consumption at 1.7 kg CO2/MWh(e). Water use is likewise dominated by requirements of uranium extraction, totaling 154 L/MWh(e). Land use is calculated at 8 x 10- 3 m2/MWh(e), over 90% of which is due to uranium extraction. Quantified impacts are limited to those resulting from activities performed within the FEFC process facilities (i.e. within the plant gates). Energy embodied in material inputs such as process chemicals and fuel cladding is identified but not explicitly quantified in this study. Inclusion of indirect energy associated with embodied energy as well as construction and decommissioning of facilities could increase the FEFC energy intensity estimate by a factor of up to 2.

  12. Development/Demonstration of an Advanced Oxy-Fuel Front-End System

    SciTech Connect (OSTI)

    Mighton, Steven, J.

    2007-08-06

    Owens Corning and other glass manufacturers have used oxy-fuel combustion technology successfully in furnaces to reduce emissions, increase throughput, reduce fuel consumption and, depending on the costs of oxygen and fuel, reduce energy costs. The front end of a fiberglass furnace is the refractory channel system that delivers glass from the melter to the forming process. After the melter, it is the second largest user of energy in a fiberglass plant. A consortium of glass companies and suppliers, led by Owens Corning, was formed to develop and demonstrate oxy/fuel combustion technology for the front end of a fiberglass melter, to demonstrate the viability of this energy saving technology to the U.S. glass industry, as a D.O.E. sponsored project. The project goals were to reduce natural gas consumption and CO2 green house gas emissions by 65 to 70% and create net cost savings after the purchase of oxygen to achieve a project payback of less than 2 years. Project results in Jackson, TN included achieving a 56% reduction in gas consumption and CO2 emissions. A subsequent installation in Guelph ON, not impacted by unrelated operational changes in Jackson, achieved a 64% reduction. Using the more accurate 64% reduction in the payback calculation yielded a 2.2 year payback in Jackson. The installation of the demonstration combustion system saves 77,000 DT/yr of natural gas or 77 trillion Btu/yr and eliminates 4500 tons/yr of CO2 emissions. This combustion system is one of several energy and green house gas reduction technologies being adopted by Owens Corning to achieve aggressive goals relating to the company’s global facility environmental footprint.

  13. Cast Stone Oxidation Front Evaluation: Preliminary Results For Samples Exposed To Moist Air

    SciTech Connect (OSTI)

    Langton, C. A.; Almond, P. M.

    2013-11-26

    The rate of oxidation is important to the long-term performance of reducing salt waste forms because the solubility of some contaminants, e.g., technetium, is a function of oxidation state. TcO{sub 4}{sup ?} in the salt solution is reduced to Tc(IV) and has been shown to react with ingredients in the waste form to precipitate low solubility sulfide and/or oxide phases. Upon exposure to oxygen, the compounds containing Tc(IV) oxidize to the pertechnetate ion, Tc(VII)O{sub 4}{sup ?}, which is very soluble. Consequently the rate of technetium oxidation front advancement into a monolith and the technetium leaching profile as a function of depth from an exposed surface are important to waste form performance and ground water concentration predictions. An approach for measuring contaminant oxidation rate (effective contaminant specific oxidation rate) based on leaching of select contaminants of concern is described in this report. In addition, the relationship between reduction capacity and contaminant oxidation is addressed. Chromate (Cr(VI) was used as a non-radioactive surrogate for pertechnetate, Tc(VII), in Cast Stone samples prepared with 5 M Simulant. Cast Stone spiked with pertechnetate was also prepared and tested. Depth discrete subsamples spiked with Cr were cut from Cast Stone exposed to Savannah River Site (SRS) outdoor ambient temperature fluctuations and moist air. Depth discrete subsamples spiked with Tc-99 were cut from Cast Stone exposed to laboratory ambient temperature fluctuations and moist air. Similar conditions are expected to be encountered in the Cast Stone curing container. The leachability of Cr and Tc-99 and the reduction capacities, measured by the Angus-Glasser method, were determined for each subsample as a function of depth from the exposed surface. The results obtained to date were focused on continued method development and are preliminary and apply to the sample composition and curing / exposure conditions described in this report. The Cr oxidation front (depth to which soluble Cr was detected) for the Cast Stone sample exposed for 68 days to ambient outdoor temperatures and humid air (total age of sample was 131 days) was determined to be about 35 mm below the top sample surface exposed. The Tc oxidation front, depth at which Tc was insoluble, was not determined. Interpretation of the results indicates that the oxidation front is at least 38 mm below the exposed surface. The sample used for this measurement was exposed to ambient laboratory conditions and humid air for 50 days. The total age of the sample was 98 days. Technetium appears to be more easily oxidized than Cr in the Cast Stone matrix. The oxidized forms of Tc and Cr are soluble and therefore leachable. Longer exposure times are required for both the Cr and Tc spiked samples to better interpret the rate of oxidation. Tc spiked subsamples need to be taken further from the exposed surface to better define and interpret the leachable Tc profile. Finally Tc(VII) reduction to Tc(IV) appears to occur relatively fast. Results demonstrated that about 95 percent of the Tc(VII) was reduced to Tc(IV) during the setting and very early stage setting for a Cast Stone sample cured 10 days. Additional testing at longer curing times is required to determine whether additional time is required to reduce 100 % of the Tc(VII) in Cast Stone or whether the Tc loading exceeded the ability of the waste form to reduce 100 % of the Tc(VII). Additional testing is required for samples cured for longer times. Depth discrete subsampling in a nitrogen glove box is also required to determine whether the 5 percent Tc extracted from the subsamples was the result of the sampling process which took place in air. Reduction capacity measurements (per the Angus-Glasser method) performed on depth discrete samples could not be correlated with the amount of chromium or technetium leached from the depth discrete subsamples or with the oxidation front inferred from soluble chromium and technetium (i.e., effective Cr and Tc oxidation fronts). Residual reduction capacity

  14. 906 IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES, VOL. 55, NO. 5, MAY 2007 RF Front-End Passive Circuit Implementation

    E-Print Network [OSTI]

    Seo, Kwang Seok

    -End Passive Circuit Implementation Including Antenna for ZigBee Applications Chan-Sei Yoo, Member, IEEE, Joong-Sung Lee Abstract--This paper presents a front-end passive circuit module for ZigBee applications using low Terms--Antenna, balun, bandpass filter, front-end pas- sive, ZigBee. I. INTRODUCTION UBIQUITOUS

  15. Journal of Statistical Physics, Vol. 90, Nos. 5/6, 1998 We study the nucleation and growth of flame fronts in slow combustion. This

    E-Print Network [OSTI]

    Grant, Martin

    fronts in slow combustion. This is modeled by a set of reaction-diffusion equations for the temperature: Nucleation; reaction-diffusion systems; flame fronts. Nucleation, Growth, and Scaling in Slow Combustion applied to understand some aspects of slow combustion. We use a phase-field model of two coupled reaction

  16. Scroll Wave Filaments Terminate in the Back of Traveling Fronts Tamas Bansagi, Jr., Christine Palczewski, and Oliver Steinbock*

    E-Print Network [OSTI]

    Steinbock, Oliver

    Scroll Wave Filaments Terminate in the Back of Traveling Fronts Tama´s Ba´nsa´gi, Jr., Christine with the 1,4-cyclohexanedione Belousov-Zhabotinsky reaction demonstrate that three-dimensional scroll waves and the wave-termination of filaments are direct consequences of the system's anomalous dispersion relation

  17. Deep-Sea Research II 49 (2002) 58895909 Characteristics and variability of the inner front of the

    E-Print Network [OSTI]

    2002-01-01

    and Ocean Sciences, University of Alaska, P.O. Box 757220, Fairbanks, AK 99775-7220, USA Abstract The inner of nutrients in the lower layer on the middle shelf and the occurrence of sufficient wind and tidal energy to as structural or structure fronts (e.g., Schumacher et al., 1979; Coachman, 1986). Alternatively

  18. Comparison of Real World Emissions of Backhoes, Front-End Loaders, and Motor Graders for B20

    E-Print Network [OSTI]

    Frey, H. Christopher

    1 Comparison of Real World Emissions of Backhoes, Front-End Loaders, and Motor Graders for B20,500Words #12;2 Abstract Field data for in-use fuel consumption and emission rates were collected for 15 nonroad vehicles using a portable emission measurement system (PEMS). Each vehicle, including 5 backhoes

  19. PHYSICAL REVIEW E 90, 042404 (2014) Solidification in soft-core fluids: Disordered solids from fast solidification fronts

    E-Print Network [OSTI]

    Knobloch, Edgar

    2014-01-01

    the study of colloidal suspensions, because of our ability to observe and track individual colloids mechanism and in this regime we are able to determine the front speed via a marginal stability analysis. We in suspension with a confocal microscope [2]. In this paper we investigate the structure a

  20. Nature and distribution of the deformation front in the Luzon Arc-Chinese continental margin collision zone at Taiwan

    E-Print Network [OSTI]

    Lin, Andrew Tien-Shun

    collision zone at Taiwan Ho-Shing Yu Institute of Oceanography, National Taiwan University, Taipei, Taiwan front, distribution, nature, seismics, Taiwan Abstract Marine seismic reflection profiles from offshore SW Taiwan combined with onland geological data are used to investigate the distri- bution and nature

  1. The visual binary AG Tri in $\\beta$ Pictoris Association: can a debris disc cause very different rotation periods of its components?

    E-Print Network [OSTI]

    Messina, Sergio; Artemenko, Svetlana; Bailey, John I; Savushkin, Alexander; Nelson, Robert H

    2015-01-01

    We measure the photometric rotation periods of the components of multiple systems in young stellar associations to investigate the causes of the observed rotation period dispersion. We present the case of the wide binary AG Tri in the 23-Myr young beta Pictoris Association consisting of K4 + M1 dwarfs. Our multi-band, multi-season photometric monitoring allowed us to measure the rotation periods of both components P_A = 12.4d and P_B = 4.66d, to detect a prominent magnetic activity in the photosphere, likely responsible for the measured radial velocity variations, and for the first time, a flare event on the M1 component AG Tri B. We investigate either the possibility that the faster rotating component may have suffered an enhanced primordial disc dispersal, starting its PMS spin-up earlier than the slower rotating component, or the possibility that the formation of a debris disc may have prevented AG Tri A from gaining part of the angular momentum from the accreting disc.

  2. The Tully-Fisher relation and its evolution with redshift in cosmological simulations of disc galaxy formation

    E-Print Network [OSTI]

    Laura Portinari; Jesper Sommer-Larsen

    2006-11-29

    We present predictions on the evolution of the Tully-Fisher (TF) relation with redshift, based on cosmological N-body/hydrodynamical simulations of disc galaxy formation and evolution. The simulations invoke star formation and stellar feedback, chemical evolution with non-instantaneous recycling, metallicity dependent radiative cooling and effects of a meta-galactic UV field, including simplified radiative transfer. At z=0, the simulated and empirical TF relations are offset by about 0.4 magnitudes (1 sigma) in the B and I bands. The origin of these offsets is somewhat unclear, but it may not necessarily be a problem of the simulations only. As to evolution, we find a brightening of the TF relation between z=0 and z=1 of about 0.85 mag in rest-frame B band, with a non-evolving slope. The brightening we predict is intermediate between the (still quite discrepant) observational estimates. This evolution is primarily a luminosity effect, while the stellar mass TF relation shows negligible evolution. The individual galaxies do gain stellar mass between z=1 and z=0, by a 50-100%; but they also correspondingly increase their characteristic circular speed. As a consequence, individually they mainly evolve ALONG the stellar mass TF relation, while the relation as such does not show any significant evolution.

  3. An Analogue Front-End ASIC Prototype Designed For PMT Signal Readout

    E-Print Network [OSTI]

    Liu, Jianfeng; Yu, Li; Liang, Yu; Qin, Jiajun; Yang, Yunfang; Wu, Weihao; Liu, Shubin; An, Qi

    2015-01-01

    The Large High Altitude Air Shower Observatory (LHAASO) is designed for high energy gamma ray and cosmic ray detection. A Water Cherenkov Detector Array which is sensitive to gamma ray showers above a few hundred GeV is proposed to survey gamma ray sources. The WCDA consists of 3600 PhotoMultiplier Tubes (PMT) which collect the Cherenkov light produced by the shower particles in water. Both high precision time and charge measurement are required over a large dynamic range from 1 photo electron (P.E.) to 4000 P.E. Prototype of an analogue front-end Application Specific Integrated Circuit (ASIC) fabricated in Chartered 0.35 {\\mu}m CMOS technology is designed to read out PMT signal in the WCDA. This ASIC employs leading edge discrimination and RC4 shaping structure; combined with the following Time-to-Digital Converter (TDC) and Analog-to-Digital Converter (ADC), both the arrival time and charge of the PMT signal can be measured. Initial test results indicate that time resolution is better than 350 ps and charge...

  4. Electromagnetic energy conversion in downstream fronts from three dimensional kinetic reconnection

    SciTech Connect (OSTI)

    Lapenta, Giovanni [Departement Wiskunde, KU Leuven, Universiteit Leuven (Belgium)] [Departement Wiskunde, KU Leuven, Universiteit Leuven (Belgium); Goldman, Martin; Newman, David [University of Colorado, Colorado 80309 (United States)] [University of Colorado, Colorado 80309 (United States); Markidis, Stefano [High Performance Computing and Visualization (HPCViz) Department, KTH Royal Institute of Technology, Stockholm (Sweden)] [High Performance Computing and Visualization (HPCViz) Department, KTH Royal Institute of Technology, Stockholm (Sweden); Divin, Andrey [Swedish Institute of Space Physics, Uppsala (Sweden)] [Swedish Institute of Space Physics, Uppsala (Sweden)

    2014-05-15

    The electromagnetic energy equation is analyzed term by term in a 3D simulation of kinetic reconnection previously reported by Vapirev et al. [J. Geophys. Res.: Space Phys. 118, 1435 (2013)]. The evolution presents the usual 2D-like topological structures caused by an initial perturbation independent of the third dimension. However, downstream of the reconnection site, where the jetting plasma encounters the yet unperturbed pre-existing plasma, a downstream front is formed and made unstable by the strong density gradient and the unfavorable local acceleration field. The energy exchange between plasma and fields is most intense at the instability, reaching several pW/m{sup 3}, alternating between load (energy going from fields to particles) and generator (energy going from particles to fields) regions. Energy exchange is instead purely that of a load at the reconnection site itself in a region focused around the x-line and elongated along the separatrix surfaces. Poynting fluxes are generated at all energy exchange regions and travel away from the reconnection site transporting an energy signal of the order of about S?10{sup ?3}W/m{sup 2}.

  5. Asymptotic freedom in the front-form Hamiltonian for quantum chromodynamics of gluons

    E-Print Network [OSTI]

    Maria Gomez-Rocha; Stanislaw D. Glazek

    2015-05-25

    Asymptotic freedom of gluons in QCD is obtained in the leading terms of their renormalized Hamiltonian in the Fock space, instead of considering virtual Green's functions or scattering amplitudes. Namely, we calculate the three-gluon interaction term in the front-form Hamiltonian for effective gluons in the Minkowski space-time using the renormalization group procedure for effective particles (RGPEP), with a new generator. The resulting three-gluon vertex is a function of the scale parameter, $s$, that has an interpretation of the size of effective gluons. The corresponding Hamiltonian running coupling constant, $g_\\lambda$, depending on the associated momentum scale $\\lambda = 1/s$, is calculated in the series expansion in powers of $g_0 = g_{\\lambda_0}$ up to the terms of third order, assuming some small value for $g_0$ at some large $\\lambda_0$. The result exhibits the same finite sensitivity to small-$x$ regularization as the one obtained in an earlier RGPEP calculation, but the new calculation is simpler than the earlier one because of a simpler generator. This result establishes a degree of universality for pure-gauge QCD in the RGPEP.

  6. Progress on the upgrade of the CMS Hadron Calorimeter Front-End electronics

    SciTech Connect (OSTI)

    Anderson, Jake; Whitmore, Juliana; /Fermilab

    2011-11-01

    We present a scheme to upgrade the CMS HCAL front-end electronics in the second long shutdown to upgrade the LHC (LS2), which is expected to occur around 2018. The HCAL electronics upgrade is required to handle the major instantaneous luminosity increase (up to 5 * 10{sup 34} cm{sup -2} s{sup -1}) and an expected integrated luminosity of {approx}3000 fb{sup -1}. A key aspect of the HCAL upgrade is to read out longitudinal segmentation information to improve background rejection, energy resolution, and electron isolation at the L1 trigger. This paper focuses on the requirements for the new electronics and on the proposed solutions. The requirements include increased channel count, additional timing capabilities, and additional redundancy. The electronics are required to operate in a harsh environment and are constrained by the existing infrastructure. The proposed solutions span from chip level to system level. They include the development of a new ASIC ADC, the design and testing of higher speed transmitters to handle the increased data volume, the evaluation and use of circuits from other developments, evaluation of commercial FPGAs, better thermal design, and improvements in the overall readout architecture. We will report on the progress of the designs for these upgraded systems, along with performance requirements and initial design studies.

  7. Magnetic field effects on the thermonuclear combustion front of Chandrasekhar mass white dwarfs

    E-Print Network [OSTI]

    Cristian R. Ghezzi; Elisabete M. de Gouveia Dal Pino; Jorge E. Horvath

    2000-12-06

    The explosion of a type Ia supernova starts in a white dwarf as a laminar deflagration at the center of the star and soon several hydrodynamic instabilities, in particular, the Rayleigh-Taylor instability, begin to act. A cellular stationary combustion and a turbulent combustion regime are rapidly achieved by the flame and maintained up to the end of the so-called flamelet regime when the transition to detonation is believed to occur. The burning velocity at these regimes is well described by the fractal model of combustion. Using a semi-analytic approach, we describe the effect of magnetic fields on the fractalization of the front considering a white dwarf with a nearly dipolar magnetic field. We find an intrinsic asymmetry on the velocity field that may be maintained up to the free expansion phase of the remnant. Considering the strongest values inferred for a white dwarf's magnetic fields with strengths up to $10^{8}-10^{9}$ G at the surface and assuming that the field near the centre is roughly 10 times greater, asymmetries in the velocity field higher than $10-20 %$ are produced between the magnetic polar and the equatorial axis of the remnant which may be related to the asymmetries found from recent spectropolarimetric observations of very young SN Ia remnants. Dependence of the asymmetry with white dwarf composition is also analyzed.

  8. Journal of Cleaner Production 13 (2005) 1931 www.elsevier.com/locate/jclepro

    E-Print Network [OSTI]

    Short, Daniel

    2005-01-01

    as a lubricant in friction material. X-ray diffraction analysis revealed Sb in 3/3 disc brake pads (range 41 and products of service. Brake pads are true products of consumption, because they are released to biological be expec- ted to be increasingly used for cars. However, cars also contain some consumption parts

  9. Redesign and Reconstruction of the Equipment Protection Systems for the Upgrading Front Ends and Beamlines at BSRF

    SciTech Connect (OSTI)

    Xiong Shenshou; Tan Yinglei; Wu Xuehui [Beijing Synchrotron Radiation Laboratory, Institute of High Energy Physics, P. O. Box 918, Branch 2-7, Beijing 100049 (China)

    2007-01-19

    The BEPC(Beijing Electron-Positron Collider) is upgraded to be BEPCII, a two-ring Electron-Positron collider. Due to the construction of the BEPCII and upgrade of the existing front ends and beamlines, all the existing EPSs(Equipment Protection Systems) have to be redesigned and reconstructed at BSRF. All the redesigned EPSs for the upgrading front ends and beamlines are a PLC- and SCADA-based equipment protection and control and monitoring system. The EPSs are used to protect BEPCII two storage rings vacuum against vacuum failures in a beamline, as well as to protect the front-end and beamline components from being damaged by synchrotron radiation. For the high-power wiggler beam lines, a fast movable mask is used to protect the blade of a fast-closing valve from damage when the fast-closing valve is triggered to close, which does not need to dump the electron beam running in BEPCII outer ring. In addition, all redesigned PLC- based EPSs are used to communicate with the same centralized monitoring computer to monitor a variety of parameters from all PLC- based EPS systems. The monitoring computer runs the SCADA (Supervisory Control And Data Acquisition) software with its own web server. Graphical HMI interfaces are used to display a few overall views of all front-end equipment operation status and the further detailed information for each EPS in a different pop-up window. On the web services, the SCADA-based centralized monitoring system provides a web browse function, etc. The design of the reconstructed systems is described in this paper.

  10. Paper No. 150. Ray, Najm and McCoy 1 Ignition front structure in a methane-air jet.1

    E-Print Network [OSTI]

    Ray, Jaideep

    Paper No. 150. Ray, Najm and McCoy 1 Ignition front structure in a methane-air jet.1 J.Ray2 , H. N-premixed methane jet in coflow air using the GRImech1.2 chemical mechanism. Ignition is initiated in the jet mixing is formed in the rich mixture region inside the jet and is observed to propagate towards the stoichiometric

  11. Discrete Symmetries on the Light Front and a General Relation connecting Nucleon Electric Dipole and Anomalous Magnetic Moments

    SciTech Connect (OSTI)

    Brodsky, Stanley J.; /SLAC; Gardner, Susan; /Kentucky U.; Hwang, Dae Sung; /Sejong U.

    2006-01-11

    We consider the electric dipole form factor, F{sub 3}(q{sup 2}), as well as the Dirac and Pauli form factors, F{sub 1}(q{sup 2}) and F{sub 2}(q{sup 2}), of the nucleon in the light-front formalism. We derive an exact formula for F{sub 3}(q{sup 2}) to complement those known for F{sub 1}(q{sup 2}) and F{sub 2}(q{sup 2}). We derive the light-front representation of the discrete symmetry transformations and show that time-reversal- and parity-odd effects are captured by phases in the light-front wave functions. We thus determine that the contributions to F{sub 2}(q{sup 2}) and F{sub 3}(q{sup 2}), Fock-state by Fock-state, are related, independent of the fundamental mechanism through which CP violation is generated. Our relation is not specific to the nucleon, but, rather, is true of spin-1/2 systems in general, be they lepton or baryon. The empirical values of the anomalous magnetic moments, in concert with empirical bounds on the associated electric dipole moments, can better constrain theories of CP violation. In particular, we find that the neutron and proton electric dipole moments echo the isospin structure of the anomalous magnetic moments, {kappa}{sup n} {approx} -{kappa}{sup p}.

  12. Discrete symmetries on the light front and a general relation connecting the nucleon electric dipole and anomalous magnetic moments

    SciTech Connect (OSTI)

    Brodsky, Stanley J. [Stanford Linear Accelerator Center, Stanford University, Stanford, California 94309 (United States); Gardner, Susan [Department of Physics and Astronomy, University of Kentucky, Lexington, Kentucky 40506-0055 (United States); Hwang, Dae Sung [Department of Physics, Sejong University, Seoul 143-747 (Korea, Republic of)

    2006-02-01

    We consider the electric dipole form factor, F{sub 3}(q{sup 2}), as well as the Dirac and Pauli form factors, F{sub 1}(q{sup 2}) and F{sub 2}(q{sup 2}), of the nucleon in the light-front formalism. We derive an exact formula for F{sub 3}(q{sup 2}) to complement those known for F{sub 1}(q{sup 2}) and F{sub 2}(q{sup 2}). We derive the light-front representation of the discrete symmetry transformations and show that time-reversal- and parity-odd effects are captured by phases in the light-front wave functions. We thus determine that the contributions to F{sub 2}(q{sup 2}) and F{sub 3}(q{sup 2}), Fock state by Fock state, are related, independent of the fundamental mechanism through which CP violation is generated. Our relation is not specific to the nucleon, but, rather, is true of spin-1/2 systems in general, be they lepton or baryon. The empirical values of the anomalous magnetic moments, in concert with empirical bounds on the associated electric dipole moments, can better constrain theories of CP violation. In particular, we find that the neutron and proton electric dipole moments echo the isospin structure of the anomalous magnetic moments, {kappa}{sup n}{approx}-{kappa}{sup p}.

  13. Discrete Symmetries on the Light Front and a General Relation Connecting Nucleon Electric Dipole and Anomalous Magnetic Moments

    E-Print Network [OSTI]

    S. J. Brodsky; S. Gardner; D. S. Hwang

    2006-02-27

    We consider the electric dipole form factor, F_3(q^2), as well as the Dirac and Pauli form factors, F_1(q^2) and F_2(q^2), of the nucleon in the light-front formalism. We derive an exact formula for F_3(q^2) to complement those known for F_1(q^2) and F_2(q^2). We derive the light-front representation of the discrete symmetry transformations and show that time-reversal- and parity-odd effects are captured by phases in the light-front wave functions. We thus determine that the contributions to F_2(q^2) and F_3(q^2), Fock state by Fock state, are related, independent of the fundamental mechanism through which CP violation is generated. Our relation is not specific to the nucleon, but, rather, is true of spin-1/2 systems in general, be they lepton or baryon. The empirical values of the anomalous magnetic moments, in concert with empirical bounds on the associated electric dipole moments, can better constrain theories of CP violation. In particular, we find that the neutron and proton electric dipole moments echo the isospin structure of the anomalous magnetic moments, kappa^n ~ - kappa^p.

  14. Discrete Symmetries on the Light Front and a General Relation Connecting Nucleon Electric Dipole and Anomalous Magnetic Moments

    E-Print Network [OSTI]

    Brodsky, S J; Hwang, D S

    2006-01-01

    We consider the electric dipole form factor, F_3(q^2), as well as the Dirac and Pauli form factors, F_1(q^2) and F_2(q^2), of the nucleon in the light-front formalism. We derive an exact formula for F_3(q^2) to complement those known for F_1(q^2) and F_2(q^2). We derive the light-front representation of the discrete symmetry transformations and show that time-reversal- and parity-odd effects are captured by phases in the light-front wave functions. We thus determine that the contributions to F_2(q^2) and F_3(q^2), Fock-state by Fock-state, are related, independent of the fundamental mechanism through which CP violation is generated. Our relation is not specific to the nucleon, but, rather, is true of spin-1/2 systems in general, be they lepton or baryon. The empirical values of the anomalous magnetic moments, in concert with empirical bounds on the associated electric dipole moments, can better constrain theories of CP violation. In particular, we find that the neutron and proton electric dipole moments echo ...

  15. The formation of compact massive self-gravitating discs in metal-free haloes with virial temperatures of ~ 13000-30000 K

    E-Print Network [OSTI]

    John A. Regan; Martin G. Haehnelt

    2008-09-30

    We have used the hydrodynamical AMR code ENZO to investigate the dynamical evolution of the gas at the centre of dark matter haloes with virial velocities of ~ 20 - 30 kms and virial temperatures of ~ 13000-30000 K at z ~ 15 in a cosmological context. The virial temperature of the dark matter haloes is above the threshold where atomic cooling by hydrogen allows the gas to cool and collapse. We neglect cooling by molecular hydrogen and metals, as may be plausible if H_2 cooling is suppressed by a meta-galactic Lyman-Werner background or an internal source of Lyman-Werner photons, and metal enrichment has not progressed very far. The gas in the haloes becomes gravitationally unstable and develops turbulent velocities comparable to the virial velocities of the dark matter haloes. Within a few dynamical times it settles into a nearly isothermal density profile over many decades in radius losing most of its angular momentum in the process. About 0.1 - 1 % of the baryons, at the centre of the dark matter haloes, collapse into a self-gravitating, fat, ellipsoidal, centrifugally supported exponential disc with scale-length of ~ 0.075-0.27 pc and rotation velocities of 25-60 kms. We are able to follow the settling of the gas into centrifugal support and the dynamical evolution of the compact disc in each dark matter halo for a few dynamical times. The dynamical evolution of the gas at the centre of the haloes is complex. In one of the haloes the gas at the centre fragments into a triple system leading to strong tidal perturbations and eventually to the in-fall of a secondary smaller clump into the most massive primary clump. The formation of centrifugally supported self-gravitating massive discs is likely to be an important intermediary stage en route to the formation of a massive black hole seed.

  16. TRENDS in Genetics Vol.17 No.10 October 2001 http://tig.trends.com 0168-9525/01/$ see front matter 2001 Elsevier Science Ltd. All rights reserved.

    E-Print Network [OSTI]

    Bulyk, Martha L.

    TRENDS in Genetics Vol.17 No.10 October 2001 http://tig.trends.com 0168-9525/01/$ ­ see front affinity. A phage display library of Zif 268 variants was constructed where the amino acids in finger 2

  17. October 1999 1999, Elsevier Science Inc., 1040-6190/99/$see front matter PII S1040-6190(99)00074-3 77 Transmission Rights and

    E-Print Network [OSTI]

    Kammen, Daniel M.

    October 1999 © 1999, Elsevier Science Inc., 1040-6190/99/$­see front matter PII S1040 not necessarily reflect the views of any of the organizations listed above. H #12;78 © 1999, Elsevier Science Inc

  18. Volume One Disc Two

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantityBonneville Power AdministrationRobust,Field-effectWorking WithTelecentricN A CountyFeet)Vladimir Koritarov

  19. Type II Cepheids in the Milky Way disc. Chemical composition of two new W Vir stars: DD Vel and HQ Car

    E-Print Network [OSTI]

    Lemasle, B; Bono, G; François, P; Saviane, I; Yegorova, I; Genovali, K; Inno, L; Galazutdinov, G; da Silva, R

    2015-01-01

    A robust classification of Cepheids into their different sub-classes and, in particular, between classical and Type II Cepheids, is necessary to properly calibrate the period-luminosity relations and for populations studies in the Galactic disc. Type II Cepheids are, however, very diverse, and classifications based either on intrinsic (period, light curve) or external parameters (e.g., [Fe/H], |z|) do not provide a unique classification. We want to ascertain the classification of two Cepheids, HQ Car and DD Vel, that are sometimes classified as classical Cepheids and sometimes as Type II Cepheids. To achieve this goal, we examine both their chemical composition and the presence of specific features in their spectra. We find emission features in the H{\\alpha} and in the 5875.64 {\\AA} He I lines that are typical of W Vir stars. The [Na/Fe] (or [Na/Zn]) abundances are typical of thick-disc stars, while BL Her stars are Na-overabundant ([Na/Fe]>+0.5 dex). Finally, the two Cepheids show a possible (HQ Car) or prob...

  20. Uranium and its relationship to host rock mineralogy in an unoxidized roll front in the Jackson group, South Texas 

    E-Print Network [OSTI]

    Prasse, Eric Martin

    1978-01-01

    Martin Prasse, B. A. , R1ce University Chairman of Advisory Comm1ttee: Dr. Hen Huang Results of fission track study of thin sect1ons of uran1um ore show that the distr1but1on of uranium on the microscopic scale in the ore is inhomogeneous, with high... of an unoxidized roll front in the Deweesville Sandstone of the Jackson Group in Karnes County, Texas. Overall, 114 ore samples and 90 overburden samples were collected and analyzed for uran1um by delayed neutron activation. Uran1um concentration varies between...

  1. Nucleon electromagnetic form factors and electroexcitation of low lying nucleon resonances in a light-front relativistic quark model

    SciTech Connect (OSTI)

    Aznauryan Inna, Burkert Volker

    2012-05-01

    We utilize a light-front relativistic quark model (LF RQM) to predict the 3q core contribution to the electroexcitation amplitudes for the {Delta}(1232)P{sub 33}, N(1440)P{sub 11}, N(1520)D{sub 13}, and N(1535)S{sub 11} up to Q{sup 2} = 12 GeV{sup 2}. The parameters of the model have been specified via description of the nucleon electromagnetic form factors in the approach that combines 3q and pion-cloud contributions in the LF dynamics.

  2. Design of a New Switching Power Supply for the ATLAS TileCAL Front-End Electronics

    E-Print Network [OSTI]

    Drake, G; The ATLAS collaboration

    2012-01-01

    We present the design of an upgraded switching power supply for the front-end electronics of the ATLAS hadron tile calorimeter (TileCAL) at the LHC. The new design features significant improvement in noise, improved fault detection, and improved reliability, while retaining the compact size, water-cooling, output control, and monitoring features in this 300 KHz design. We discuss the steps taken to improve the design. We present the results from extensive radiation testing to qualify the design, including SEU sensitivity. We also present our reliability analysis. Production of 2400 new bricks for the detector is currently in progress, and we present preliminary results from the production checkout.

  3. Design of a New Switching Power Supply for the ATLAS TileCal Front-End Electronics

    E-Print Network [OSTI]

    Drake, Gary; The ATLAS collaboration

    2012-01-01

    We present the design of an upgraded switching power supply for the front-end electronics of the ATLAS Hadron Tile Calorimeter. The new design features significant improvement in noise, improved fault detection, and improved reliability, while retaining the compact size, water-cooling, output control, and monitoring features. We discuss the steps taken to improve the design. We present the results from extensive radiation testing to qualify the design, including SEU sensitivity. We also present our reliability analysis. Production of 2400 new bricks for the detector is in progress, and we present preliminary results from the production checkout.

  4. An Upgraded Front-End Switching Power Supply Design for the ATLAS TileCAL Detector of the LHC

    E-Print Network [OSTI]

    Drake, G; The ATLAS collaboration; De Lurgio, P; Henriques, A; Minashvili, I; Nemecek, S; Price, L; Proudfoot, J; Stanek, R

    2011-01-01

    We present the design of an upgraded switching power supply brick for the front-end electronics of the ATLAS hadron tile calorimeter (TileCAL) at the LHC. The new design features significant improvement in noise, improved fault detection, and generally a more robust design, while retaining the compact size, water-cooling, output control, and monitoring features in this 300 KHz design. We discuss the improvements to the design, and the radiation testing that we have done to qualify the design. We also present our plans for the production of 2400 new bricks for installation on the detector in 2013.

  5. Effect of Front-Side Silver Metallization on Underlying n+-p Junction in Multicrystalline Silicon Solar Cells: Preprint

    SciTech Connect (OSTI)

    Jiang, C. S.; Li, Z. G.; Moutinho, H. R.; Liang, L.; Ionkin, A.; Al-Jassim, M. M.

    2012-06-01

    We report on the effect of front-side Ag metallization on the underlying n+-p junction of multicrystalline Si solar cells. The junction quality beneath the contacts was investigated by characterizing the uniformities of the electrostatic potential and doping concentration across the junction, using scanning Kelvin probe force microscopy and scanning capacitance microscopy. We investigated cells with a commercial Ag paste (DuPont PV159) and fired at furnace setting temperatures of 800 degrees, 840 degrees, and 930 degrees C, which results in actual cell temperatures ~100 degrees C lower than the setting temperature and the three cells being under-, optimal-, and over-fired. We found that the uniformity of the junction beneath the Ag contact was significantly degraded by the over-firing, whereas the junction retained good uniformity with the optimal- and under-fire temperatures. Further, Ag crystallites with widely distributed sizes from <100 nm to several ?m were found at the Ag/Si interface of the over-fired cell. Large crystallites were imaged as protrusions into Si deeper than the junction depth. However, the junction was not broken down; instead, it was reformed on the entire front of the crystallite/Si interface. We propose a mechanism of the junction-quality degradation, based on emitter Si melting at the temperature around the Ag-Si eutectic point during firing, and subsequent recrystallization with incorporation of impurities in the Ag paste and with formation of crystallographic defects during quenching.

  6. Single Event Effect Hardness for the Front-end ASICs Applied in BGO Calorimeter of DAMPE Satellite

    E-Print Network [OSTI]

    Gao, Shan-Shan; Feng, Chang-Qing; Xi, Kai; Liu, Shu-Bin; An, Qi

    2015-01-01

    Dark Matter Particle Explorer (DAMPE) is a Chinese scientific satellite designed for cosmic ray study with a primary scientific goal of indirect search of dark matter particles. As a crucial sub-detector, BGO calorimeter measures the energy spectrum of cosmic rays in the energy range from 5 GeV to 10 TeV. In order to implement high-density front-end electronics (FEE) with the ability to measure 1848 signals from 616 photomultiplier tubes on the strictly constrained satellite platform, two kinds of 32-channel front-end ASICs, VA160 and VATA160, are customized. However, a space mission period of more than 3 years makes single event effect (SEE) a probable threat to reliability. In order to evaluate the SEE sensitivity of the chips and verify the effectiveness of mitigation methods, a series of laser-induced and heavy ion-induced SEE tests were performed. Benefiting from the single event latch-up (SEL) protection circuit for power supply, the triple module redundancy (TMR) technology for the configuration regist...

  7. MODELLING A CIRCUMSTELLAR DISC TRACED BY METHANOL MASERS. M. R. Pestalozzi, School of Physics, Astronomy and Mathematics, Univ. of Hertfordshire, AL9 10AB Hatfield, UK (michele@star.herts.ac.uk), M. Elitzur, Univ. of

    E-Print Network [OSTI]

    De Buizer, James Michael

    MODELLING A CIRCUMSTELLAR DISC TRACED BY METHANOL MASERS. M. R. Pestalozzi, School of Physics-Planck Institut f¨ur Radioastronomie, Bonn, Germany. We present the accurate modelling of one methanol maser in which many methanol masers have been detected and mark different objects (see Poster by V. Minier et al

  8. Mon. Not. R. Astron. Soc. 000, 18 (2015) Printed 18 February 2015 (MN LATEX style file v2.2) Tearing up a misaligned accretion disc with a binary companion

    E-Print Network [OSTI]

    Price, Daniel

    2015-01-01

    2 & Daniel J. Price4 1University of Ege, Department of Astronomy & Space Sciences, Bornova, 35100 the chaotic nature of AGN accretion (King & Pringle 2006, 2007). The effect on the disc in all these cases is similar. The lack of symmetry produces a torque on misaligned rings of gas which makes their orbits

  9. Operation Greenhouse: Scientific Director's report of atomic weapon tests at Eniwetok, 1951. Annex 1. 9. Air drop instrumentation. Part 3. Disc camera

    SciTech Connect (OSTI)

    Not Available

    1985-09-01

    The disc camera was designed for use to determine the growth characteristic of the fireball and so the yield. The instrument has three separate optical systems and can record three separate streak images of the fireball on a rotating glass photographic plate. The angular velocity of the photoplate at the time of exposure is determined by marker pips recorded on the photoplate. The marker generator is gated by a phototube and is turned off by a time delay. Time to minimum can be determined directly from the streaks and by the use of the scaling laws. Bhangmeter yield can also be determined. For Operation Greenhouse, two cameras were operated in phototowers. Good records were obtained on the first two shots. On the George Shot, which was a daylight test, the photocell in the fiducial marker did not function and no records were attained. The cameras were not operated on the Item Shot. The yields derived compare favorably with those from other fireball determinations.

  10. Master Thesis High torque, high impact braking

    E-Print Network [OSTI]

    Daraio, Chiara

    to add a break in each actuated joint, so it is not necesary to wasted energy during the stoped time to any sort of actuator, e.g., hidraulic, electric, . . . Even though they have been deeply studied

  11. Generalized parton distributions and transverse densities in a light-front quark-diquark model for the nucleons

    E-Print Network [OSTI]

    Chandan Mondal; Dipankar Chakrabarti

    2015-06-17

    We present a study of the generalized parton distributions for the quarks in a proton in both momentum and position spaces using the light-front wave functions of a quark-diquark model for the nucleon predicted by the soft-wall model of AdS/QCD. The results are compared with the soft-wall AdS/QCD model of proton GPDs for zero skewness. We also calculate the GPDs for nonzero skewness. We observe that the GPDs have a diffraction pattern in longitudinal position space, as seen before in other models. Then we present a comparitive study of the nucleon charge and anomalous magnetization densities in the transverse plane. Flavor decompositions of the form factors and transverse densities are also discussed.

  12. Isoperimetric inequalities for wave fronts and a generalization of Menzin's conjecture for bicycle monodromy on surfaces of constant curvature

    E-Print Network [OSTI]

    Howe, Sean; Zakharevich, Valentin

    2009-01-01

    We prove generalizations of the isoperimetric inequality for both spherical and hyperbolic wave fronts (i.e. piecewise smooth curves which may have cusps). We then discuss "bicycle curves" using the generalized isoperimetric inequalities. The euclidean model of a bicycle is a unit segment AB that can move so that it remains tangent to the trajectory of point A (the rear wheel is fixed on the bicycle frame). We extend this definition to a general Riemannian manifold, and concern ourselves in particular with bicycle curves in the hyperbolic plane H^2 and on the sphere S^2. We prove results along the lines of those proven by Levi and Tabachnikov and resolve both spherical and hyperbolic versions of Menzin's conjecture, which relates the area bounded by a curve to its associated monodromy map.

  13. Quarterly Journal of the Royal Meteorological Society Q. J. R. Meteorol. Soc. 136: 962977, April 2010 Part B Evolution and structure of a cold front in an Alpine valley as

    E-Print Network [OSTI]

    Gohm, Alexander

    is a Doppler lidar that had been operated in the Wipp Valley (Austria). The cold front approached the European part of the cold air had entered the adjacent north­south aligned Wipp Valley. Asynthesisof in the Wipp Valley was an atmospheric density current characterized by an elevated head, a front

  14. Front, left to right: Mark Handy, Tuncay Taymaz, Jean-Pierre Brun, Walter Mooney. Back, left to right: Patience Cowie, Christian Teyssier, Alain Vauchez, Kevin Furlong,

    E-Print Network [OSTI]

    Cowie, Patience

    Front, left to right: Mark Handy, Tuncay Taymaz, Jean-Pierre Brun, Walter Mooney. Back, left transitions occur? Identifying these basic questions is straightforward, but answering them is prob- lematic area in back- ground shows the large range of conditions for faulting, from nucleation and localiza

  15. Dynamical evolution of Rayleigh-Taylor and Richtmyer-Meshkov mixing fronts Physics Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545

    E-Print Network [OSTI]

    New York at Stoney Brook, State University of

    derive § an analytic solution for the dynamic evolution of mixing fronts driven by constant acceleration in a multifluid system produce buoyancy and shear driven 8 instabilities at an interface between distinct fluids 9 Rayleigh-T ¨ aylor ©RT ¨ and impulsive acceleration Richtmyer-Meshkov instabilities, from a simple physics

  16. 0045-2068/$ -see front matter 2004 Elsevier Inc. All rights reserved. doi:10.1016/j.bioorg.2004.04.002

    E-Print Network [OSTI]

    Theodorakis, Emmanuel

    0045-2068/$ - see front matter 2004 Elsevier Inc. All rights reserved. doi:10.1016/j.bioorg.2004.04.002 Bioorganic Chemistry 32 (2004) 274­289 www.elsevier.com/locate/bioorg Hydrophilic molecular rotor derivatives 22 March 2004 Available online 13 May 2004 Abstract Recent research shows high potential for some p

  17. ABSTRACT: FRANKEL K.L. & PAZZAGLIA F.J., Tectonic geomorpholo-gy, drainage basin metrics, and active mountain fronts. (IT ISSN 1724-

    E-Print Network [OSTI]

    Frankel, Kurt L.

    and deformational style in the western United States and Italy. Our study is guided by initial results obtained from United States. We attribute the higher variance to the effects of overall larger drainage basin size settings. Here we report results from test cases on five mountain fronts with variable rates of rock uplift

  18. Local waiting time fluctuations along a randomly pinned crack front Knut Jrgen Maly, 1 Stephane Santucci, 1 Jean Schmittbuhl, 2 and Renaud Toussaint 2

    E-Print Network [OSTI]

    Toussaint, Renaud

    that the fracture front dynamics is governed by local and irregular avalanches with very large size and velocity) # S -# with # = 1.7±0.1. Above a characteristic length scale of disorder Ld # 15µm, the avalanche clusters become], magnetic domain walls [12], or wet­ ting contact lines [13--15], where elasticity and disorder compete

  19. Sedimentation in theTonga forearc is dominated by the redeposition of volcaniclastic sediment from the arc volcanic front by mass flows

    E-Print Network [OSTI]

    Clift, Peter

    ABSTRACT Sedimentation in theTonga forearc is dominated by the redeposition of volcaniclastic sediment from the arc volcanic front by mass flows and turbidity currents onto the adjacent Tonga Platform, the shallow- est, flattest part of the forearc region.The greatest sediment thicknesses accumulate in debris

  20. Mechanisms for plasma and reactive ion etch-front roughening Jason T. Drotar, Y.-P. Zhao, T.-M. Lu, and G.-C. Wang

    E-Print Network [OSTI]

    Wang, Gwo-Ching

    width w induced by SF6 plasma etching of silicon surfaces increases linearly with etch time (w t1Mechanisms for plasma and reactive ion etch-front roughening Jason T. Drotar, Y.-P. Zhao, T.-M. Lu, Troy, New York 12180-3590 Received 14 April 1999; revised manuscript received 1 September 1999 Through