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Note: This page contains sample records for the topic "variable air-volume system" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
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1

Optimized Fan Control In Variable Air Volume HVAC Systems Using Static Pressure Resets: Strategy Selection and Savings Analysis.  

E-Print Network (OSTI)

??The potential of static pressure reset (SPR) control to save fan energy in variable air volume HVAC systems has been well documented. Current research has… (more)

Kimla, John

2010-01-01T23:59:59.000Z

2

Optimized Fan Control In Variable Air Volume HVAC Systems Using Static Pressure Resets: Strategy Selection and Savings Analysis  

E-Print Network (OSTI)

The potential of static pressure reset (SPR) control to save fan energy in variable air volume HVAC systems has been well documented. Current research has focused on the creation of reset strategies depending on specific system features...

Kimla, John

2010-07-14T23:59:59.000Z

3

Optimal supply air temperature with respect to energy use in a variable air volume system  

Science Journals Connector (OSTI)

In a variable air volume (VAV) system with 100% outdoor air, the cooling need in the building is satisfied with a certain air flow at a certain supply air temperature. To minimize the system energy use, an optimal supply air temperature can be set dependent on the load, specific fan power (SFP), chiller coefficient of performance, outdoor temperature and the outdoor relative humidity. The theory for an optimal supply air temperature is presented and the heating, ventilation and air-conditioning (HVAC) energy use is calculated depending on supply air temperature control strategy, average U-value of the building envelope and two outdoor climates. The analyses show that controlling the supply air temperature optimally results in a significantly lower HVAC energy use than with a constant supply air temperature. The optimal average U-value of the building envelope is in practise mostly zero.

Fredrik Engdahl; Dennis Johansson

2004-01-01T23:59:59.000Z

4

Variable Speed Drive Volumetric Tracking (VSDVT) for Airflow Control in Variable Air Volume (VAV) Systems  

E-Print Network (OSTI)

Volume Systems.? Proceedings of ACEEE 1994 Summer Study on Energy Efficiency in Buildings, Vol. 5, pp. 219-223. 3. Liu M., Zhu Y., Claridge D.E., and White E., 1997. ?Impact of Static Pressure Set Level on HVAC Energy Consumption and Indoor... Volume Systems.? Proceedings of ACEEE 1994 Summer Study on Energy Efficiency in Buildings, Vol. 5, pp. 219-223. 3. Liu M., Zhu Y., Claridge D.E., and White E., 1997. ?Impact of Static Pressure Set Level on HVAC Energy Consumption and Indoor...

Liu, M.

2002-01-01T23:59:59.000Z

5

Neuro-optimal operation of a variable air volume HVAC&R system  

Science Journals Connector (OSTI)

Low operational efficiency especially under partial load conditions and poor control are some reasons for high energy consumption of heating, ventilation, air conditioning and refrigeration (HVAC&R) systems. To improve energy efficiency, HVAC&R systems should be efficiently operated to maintain a desired indoor environment under dynamic ambient and indoor conditions. This study proposes a neural network based optimal supervisory operation strategy to find the optimal set points for chilled water supply temperature, discharge air temperature and VAV system fan static pressure such that the indoor environment is maintained with the least chiller and fan energy consumption. To achieve this objective, a dynamic system model is developed first to simulate the system behavior under different control schemes and operating conditions. A multi-layer feed forward neural network is constructed and trained in unsupervised mode to minimize the cost function which is comprised of overall energy cost and penalty cost when one or more constraints are violated. After training, the network is implemented as a supervisory controller to compute the optimal settings for the system. Simulation results show that compared to the conventional night reset operation scheme, the optimal operation scheme saves around 10% energy under full load condition and 19% energy under partial load conditions.

Min Ning; M. Zaheeruddin

2010-01-01T23:59:59.000Z

6

Improved Air Volume Control Logic for VAV Systems  

E-Print Network (OSTI)

In a VAV (variable air volume) system, the set point of the static pressure (usually measured at 213 downstream of the main supply air duct) is maintained by modulating the fan speed or inlet guide vane position. The set point of the static pressure...

Wei, G.; Claridge, D. E.; Sakuri, Y.; M. Liu

2000-01-01T23:59:59.000Z

7

CALIFORNIA ENERGY Advanced Variable Air Volume  

E-Print Network (OSTI)

on VAV airside system design. Total large office building energy savings of up to 12% are achievable and controls for commercial buildings and in performing peer reviews of mechanical designs of commercial was developed as part of the Integrated Energy Systems -- Productivity and Building Science project, a Public

8

Application of Wireless Sensor Network (WSN) Technologies in Optimal Static Pressure Reset in Variable Air Volume (VAV) System  

E-Print Network (OSTI)

Optimization of the static pressure reset is always critical in the pursuit of maximum savings of fan power and thermal energy consumption in a VAV system. This paper theoretically investigated three static pressure reset methods, i.e. VAV terminal...

Zheng, K.; Li, H.; Yang, H.

2007-01-01T23:59:59.000Z

9

Integrating VAV zone requirements with supply fan operation. [Variable Air Volume  

SciTech Connect

The use of communicating direct digital controls (DDC) with distributed intelligence offers new opportunities for energy conservation while maintaining occupant comfort in commercial buildings. Integrating control within a single DDC panel improves performance. Integrating control by communications between multiple controllers can further enhance system operation. One example is a DDC static pressure reset strategy for supply fan operation in variable air volume (VAV) supply air distribution systems. This strategy integrates the requirements of the VAV terminal units serving the building zones to minimize fan energy use. This article describes terminal unit operation, supply fan control, concurrent polling, operational data and power savings.

Warren, M.L. (ASI Controls, San Ramon, CA (United States)); Norford, L.K. (Massachusetts Inst. of Tech., Cambridge (United States))

1993-04-01T23:59:59.000Z

10

Compatible and Cost-Effective Fault Diagnostic Solutions for Air Handling Unit–Variable Air Volume and Air Handling Unit–Constant Air Volume Systems- 2014 BTO Peer Review  

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

Presenter: Jin Wen, Drexel University The goal of this project is to develop and demonstrate a library of diagnostics decision-support tools for medium-to-large-sized commercial buildings that use air handling unit (AHU) systems that can enable cost-effective diagnostics solutions (both embedded and add-on solutions) for existing buildings.

11

96 ASHRAE Transactions: Research Current duct design methods for variable air volume  

E-Print Network (OSTI)

.Hourlyairflowrequirements, part-load fan characteristics, and duct static pressure control are incorporated into the problem airflow. Fan power is also influ- enced if static pressure at the end of the longest duct line for effective, energy-efficient, and comfortable heating, ventilat- ing, and air-conditioning (HVAC) systems

12

Research on Fuzzy Regulation Strategies in the Constant Air Volume Air Conditioning System  

E-Print Network (OSTI)

Yifeng Wu Honglin Wang Doctoral Candidate Associate Professor Master Master Master Master School of Municipal & Environmental Eng, Harbin Institute of Technology Harbin P.R. China, 150090 hitbai@163.com Abstract: The energy consumption... region and the same operating strategy was adopted[1]. Wang Li analyzed the temperature control principles to achieve economical operation in CAV system, and presented improved control strategy to integrate fresh air control with indoor air...

Bai, T.; Zhang, J.; Ning, N.; Tong, K.; Wu, Y.; Wang, H.

2006-01-01T23:59:59.000Z

13

Energy Savings for Occupancy-Based Control (OBC) of Variable-Air-Volume (VAV) Systems  

SciTech Connect

This study evaluates the savings potential of occupancy based control (OBC) for large office buildings with VAV terminal boxes installed.

Zhang, Jian; Lutes, Robert G.; Liu, Guopeng; Brambley, Michael R.

2013-01-24T23:59:59.000Z

14

Room Temperature Control During Season Switchover with Single Duct Variable Air Volume System Without Reheat  

E-Print Network (OSTI)

of VAV boxes to maintain room temperature at their setpoints. The thermostat action is switched from direct acting (DA) to reverse acting (RA) when the season changes from fall to winter and vice versa from winter to spring, based on the out side air...

Liu, C.; Deng, S.; Claridge, D. E.; Turner, W. D.; Bruner, H.

2003-01-01T23:59:59.000Z

15

Improving Control of a Dual-Duct Single-Fan Variable Air Volume Systems  

E-Print Network (OSTI)

cold and hot air duct static pressure set points is presented. The paper also explores the interactions between the cold and hot deck temperatures and duct static pressures, and discusses the impact of non-ideal deck temperature settings on duct static...

Wei, G.; Martinez, J.; Minihan, T.; Brundidge, T.; Claridge, D. E.; Turner, W. D.

2003-01-01T23:59:59.000Z

16

A study on static pressure reset and instability in variable air volume HVAC systems.  

E-Print Network (OSTI)

??This project began with testing five different versions of supply duct static pressure reset strategies that fall into two general categories: Proportional plus Integral control… (more)

Housholder, Brian Wayne

2011-01-01T23:59:59.000Z

17

System dynamics based models for selecting HVAC systems for office buildings: a life cycle assessment from carbon emissions perspective.  

E-Print Network (OSTI)

??This study aims to explore the life cycle environmental impacts of typical heating ventilation and air condition (HVAC) systems including variable air volume (VAV) system,… (more)

Chen, S

2011-01-01T23:59:59.000Z

18

Automatic Control Technology in the HVAC System  

Science Journals Connector (OSTI)

In the field of VAV air-conditioning system (Variable Air Volume, VAV) control theory and practical study, the paper analyzed the methods used by the China's VAV control procedures including Static Pressure Control, Variable Pressure Control and Total ...

Ren Tao; Gao Jingmin; Jia Wenwen

2009-01-01T23:59:59.000Z

19

Impacts of Static Pressure Reset on VAV System Air Leakage, Fan Power and Thermal Energy - Part I: Theoretical Model and Simulation  

E-Print Network (OSTI)

As for a variable air volume (VAV) system, the air duct static pressure is a typical control variable maintained by modulating supply fan speed. The static pressure equals to the summation of the duct pressure loss downstream of the sensor...

Liu, M.; Feng, J.; Wang, Z.; Wu, L.; Zheng, K.; Pang, W.

2007-01-01T23:59:59.000Z

20

Commissioning and Diagnosis of VAV Air-Conditioning Systems  

E-Print Network (OSTI)

This paper presents a fault detection and diagnosis (FDD) strategy based on system knowledge, qualitative states and object-oriented statistical process control (SPC) models for typical pressure-independent variable air volume (VAV) air...

Qin, J.; Wang, S.; Chan, C.; Xiao, F.

2006-01-01T23:59:59.000Z

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


21

Wireless Demand Response Controls for HVAC Systems  

E-Print Network (OSTI)

art VAV: variable-air-volume VFD: variable frequency drivespeed command to the variable frequency drive(s) (VFDs). The

Federspiel, Clifford

2010-01-01T23:59:59.000Z

22

Design and evaluation of a prototype laboratory emission control device for use in a variable air volume, face velocity reducing system  

E-Print Network (OSTI)

by the work environment and the work practices of those using the hood. Burton complied the following table, illustrating past and current recommendations from various agencies, yet recommends 100 feet per minute [FPM] along with good work practices.... " ' ~Oi t Recommended Face Velocit FPM American National Standards Institute (ANSI), Z9. 5, 1992 80-120 American Conference of Governmental Industrial Hygienists (ACGIH) 60-100 National Institute for Occupational Safety and Health (NIOSH) 100...

Lacey, Steven Edward

2012-06-07T23:59:59.000Z

23

Variable buoyancy system metric  

E-Print Network (OSTI)

Over the past 20 years, underwater vehicle technology has undergone drastic improvements, and vehicles are quickly gaining popularity as a tool for numerous oceanographic tasks. Systems used on the vehicle to alter buoyancy, ...

Jensen, Harold Franklin

2009-01-01T23:59:59.000Z

24

Variable frequency microwave furnace system  

DOE Patents (OSTI)

A variable frequency microwave furnace system (10) designed to allow modulation of the frequency of the microwaves introduced into a furnace cavity (34) for testing or other selected applications. The variable frequency microwave furnace system (10) includes a microwave signal generator (12) or microwave voltage-controlled oscillator (14) for generating a low-power microwave signal for input to the microwave furnace. A first amplifier (18) may be provided to amplify the magnitude of the signal output from the microwave signal generator (12) or the microwave voltage-controlled oscillator (14). A second amplifier (20) is provided for processing the signal output by the first amplifier (18). The second amplifier (20) outputs the microwave signal input to the furnace cavity (34). In the preferred embodiment, the second amplifier (20) is a traveling-wave tube (TWT). A power supply (22) is provided for operation of the second amplifier (20). A directional coupler (24) is provided for detecting the direction of a signal and further directing the signal depending on the detected direction. A first power meter (30) is provided for measuring the power delivered to the microwave furnace (32). A second power meter (26) detects the magnitude of reflected power. Reflected power is dissipated in the reflected power load (28).

Bible, Don W. (Clinton, TN); Lauf, Robert J. (Oak Ridge, TN)

1994-01-01T23:59:59.000Z

25

Variable frequency microwave furnace system  

DOE Patents (OSTI)

A variable frequency microwave furnace system designed to allow modulation of the frequency of the microwaves introduced into a furnace cavity for testing or other selected applications. The variable frequency microwave furnace system includes a microwave signal generator or microwave voltage-controlled oscillator for generating a low-power microwave signal for input to the microwave furnace. A first amplifier may be provided to amplify the magnitude of the signal output from the microwave signal generator or the microwave voltage-controlled oscillator. A second amplifier is provided for processing the signal output by the first amplifier. The second amplifier outputs the microwave signal input to the furnace cavity. In the preferred embodiment, the second amplifier is a traveling-wave tube (TWT). A power supply is provided for operation of the second amplifier. A directional coupler is provided for detecting the direction of a signal and further directing the signal depending on the detected direction. A first power meter is provided for measuring the power delivered to the microwave furnace. A second power meter detects the magnitude of reflected power. Reflected power is dissipated in the reflected power load. 5 figs.

Bible, D.W.; Lauf, R.J.

1994-06-14T23:59:59.000Z

26

E-Print Network 3.0 - air volume air Sample Search Results  

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

Use Summary: pressure, and for modeling the change in system pressure as function of compressed air storage volume... important system variables such as system pressure and...

27

Development of an isothermal 2D zonal air volume model with impulse  

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

Development of an isothermal 2D zonal air volume model with impulse Development of an isothermal 2D zonal air volume model with impulse conservation Title Development of an isothermal 2D zonal air volume model with impulse conservation Publication Type Conference Paper Year of Publication 2010 Authors Victor, Norrefeldt, Thierry Stephane Nouidui, and Gunnar Gruen Conference Name Clima 2010, 10th Rehva World Congress "Sustainable Energy Use in Buildings" Conference Location Antalya, Turkey Abstract This paper presents a new approach to model air flows with a zonal model. The aim of zonal models is to perform quick simulations of the air distribution in rooms. Therefore an air volume is subdivided into several discrete zones, typically 10 to 100. The zones are connected with flow elements computing the amount of air exchanged between them. In terms of complexity and needed computational time zonal models are a compromise between CFDcalculations and the approximation of perfect mixing. In our approach the air flow velocity is used as property of the zones. Thus the distinction between normal zones and jet or plume influenced zones becomes obsolete. The model is implemented in the object oriented and equation based language Modelica. A drawback of the new formulation is that the calculated flow pattern depends on the discretization. Nevertheless, the results show that the new zonal model performs well and is a useful extension to existing models.

28

Variable pressure power cycle and control system  

DOE Patents (OSTI)

A variable pressure power cycle and control system that is adjustable to a variable heat source is disclosed. The power cycle adjusts itself to the heat source so that a minimal temperature difference is maintained between the heat source fluid and the power cycle working fluid, thereby substantially matching the thermodynamic envelope of the power cycle to the thermodynamic envelope of the heat source. Adjustments are made by sensing the inlet temperature of the heat source fluid and then setting a superheated vapor temperature and pressure to achieve a minimum temperature difference between the heat source fluid and the working fluid.

Goldsberry, Fred L. (Spring, TX)

1984-11-27T23:59:59.000Z

29

Supply Fan Control for Constant Air Volume Air Handling Units  

E-Print Network (OSTI)

Since terminal boxes do not have a modulation damper in constant volume (CV) air handling unit (AHU) systems, zone reheat coils have to be modulated to maintain the space temperature with constant supply airflow. This conventional control sequence...

Cho, Y.; Wang, G.; Liu, M.

2007-01-01T23:59:59.000Z

30

Development of models for series and parallel fan variable air volume terminal units  

E-Print Network (OSTI)

for the series and parallel units, with coefficients varying by size and manufacturer. Statistical modeling utilized SAS software (2002). Fan power and airflow data were collected at downstream static pressures over a range from 0.1 to 0.5 in. w.g. (25 to 125 Pa...

Furr, James C., Jr

2007-09-17T23:59:59.000Z

31

Procedure and Application for Determining the Cold Deck and Hot Deck Airflow in a Dual-Duct System  

E-Print Network (OSTI)

This paper introduces an innovative method to determine the cold and hot airflow through a dual-duct variable air volume (VAV) system. The actual building load can be identified based on the calculated airflow and temperature for both the cold...

Liu, G.; Mingsheng, L.

2006-01-01T23:59:59.000Z

32

Empowering Variable Renewables: Options for Flexible Electricity Systems |  

Open Energy Info (EERE)

Empowering Variable Renewables: Options for Flexible Electricity Systems Empowering Variable Renewables: Options for Flexible Electricity Systems Jump to: navigation, search Tool Summary LAUNCH TOOL Name: Empowering Variable Renewables: Options for Flexible Electricity Systems Agency/Company /Organization: International Energy Agency Sector: Energy Focus Area: Renewable Energy Topics: Market analysis, Technology characterizations Resource Type: Publications Website: www.iea.org/g8/2008/Empowering_Variable_Renewables.pdf Empowering Variable Renewables: Options for Flexible Electricity Systems Screenshot References: Empowering Variable Renewables: Options for Flexible Electricity Systems[1] Summary "Increasing the share of renewables in energy portfolios is a key tool in the drive to reduce anthropogenic carbon dioxide emissions, as well as

33

Experimental Study of the Circulation Air Volume of Recirculation Evaporative Cooling  

E-Print Network (OSTI)

ICEBO2006, Shenzhen, China HVAC Technologies for Energy Efficiency, Vol. IV-11-3 Experimental Study of the Circulation Air Volume of Recirculation Evaporative Cooling 1 Jun Xiong ZeHua Liu Chao Wang GuoJie Chen Bachelor Senior.... Pre-design and design tools for evapora- tive cooling[J]. ASHRAE Transaction: Symposia. 2001.Vol. 107 part1: 501-510. [5] LiangShi Ding, JianJun Wang, MingJian Jiang. Investigations of the thermal performance of in- direct evaporative plate heat...

Xiong, J.; Liu, Z.; Wang, C.; Chen, G.

2006-01-01T23:59:59.000Z

34

Implementation of the Laboratory Air Handling Unit Systems (LAHU)  

E-Print Network (OSTI)

Implementation of the Laboratory Air Handling Unit Systems (LAHU) Y. Cui Graduate Student Energy Systems Laboratory University of Nebraska-Lincoln Omaha, NE, USA M. Liu, Ph.D., P.E. Associate Professor Energy Systems Laboratory...-around coils [18, 19], the variable air volume (VAV) fume hoods [8-16] and the usage-based control devices (UBC) [17]. These measures have effectively reduced the cooling energy, preheat energy and fan power consumption, and sometime, improved indoor...

Cui, Y.; Liu, M.; Conger, K.

2003-01-01T23:59:59.000Z

35

ASSESSMENT OF VARIABLE EFFECTS OF SYSTEMS WITH DEMAND RESPONSE RESOURCES  

E-Print Network (OSTI)

ASSESSMENT OF VARIABLE EFFECTS OF SYSTEMS WITH DEMAND RESPONSE RESOURCES BY ANUPAMA SUNIL KOWLI B of consumers - called demand response resources (DRRs) - whose role has become increasingly important

Gross, George

36

Comparison of energy efficiency between variable refrigerant flow systems and ground source heat pump systems  

E-Print Network (OSTI)

Comparison of energy efficiency between variable refrigeranttheir superior energy efficiency. The variable refrigerantfew studies reporting the energy efficiency of VRF systems

Hong, Tainzhen

2010-01-01T23:59:59.000Z

37

Quantifying the Variable Effects of Systems with Demand Response Resources  

E-Print Network (OSTI)

Quantifying the Variable Effects of Systems with Demand Response Resources Anupama Kowli and George in the electricity industry. In particular, there is a new class of consumers, called demand response resources (DRRs

Gross, George

38

Variable emissivity laser thermal control system  

DOE Patents (OSTI)

A laser thermal control system for a metal vapor laser maintains the wall mperature of the laser at a desired level by changing the effective emissivity of the water cooling jacket. This capability increases the overall efficiency of the laser.

Milner, Joseph R. (Livermore, CA)

1994-01-01T23:59:59.000Z

39

Commercial thermal distribution systems, Final report for CIEE/CEC  

E-Print Network (OSTI)

air-volume HVAC systems, static pressures across theIn VAY HVAC systems, the static pressures may likely changefor the Static Pressure Analysis Tool are: • HVAC schedule

Xu, T.

2011-01-01T23:59:59.000Z

40

Strategies and Decision Support Systems for Integrating Variable Energy  

Open Energy Info (EERE)

Strategies and Decision Support Systems for Integrating Variable Energy Strategies and Decision Support Systems for Integrating Variable Energy Resources in Control Centers for Reliable Grid Operations: Global Best Practices, Examples of Excellence and Lessons Learned Jump to: navigation, search Tool Summary LAUNCH TOOL Name: Strategies and Decision Support Systems for Integrating Variable Energy Resources in Control Centers for Reliable Grid Operations: Global Best Practices, Examples of Excellence and Lessons Learned Agency/Company /Organization: United States Department of Energy Sector: Climate, Energy Focus Area: Renewable Energy, Grid Assessment and Integration, Wind Topics: Best Practices Resource Type: Lessons learned/best practices, Publications, Technical report Website: www1.eere.energy.gov/wind/pdfs/doe_wind_integration_report.pdf

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


41

Control Humidity With Single-Duct, Single-Zone, Constant Air Volume System  

E-Print Network (OSTI)

for the AHLJ after Adjusted Conditions I I Return Fan: off; Return Damper: closed; Outside Air Damper: closed (signal) I 7- 14-99 9:44 AM AHU Dimensions Total Air Flow (CW Average Velocity (FPM) Temperature ("F) Humidity (% RH) Dew Point (OF... (FPM) Humidity (% RH) 1 83.0 -... r------ L -/ Dew Point (OF) Static Pressure supply 24" x 24" 4450 1180 Outside Air N/ A 2490 N/ A Mix Air 20" x 36" 4530 1091 T~mnrmt~w~ (OF) I 67.6 1 73.0 I 72.1 I 85.7 I . - 62.9 10.75 Return Air...

Chen, H.; Deng, S.; Bruner, H. L.; Claridge, D. E.

2000-01-01T23:59:59.000Z

42

High efficiency pool filtering systems utilising variable frequency drives  

Science Journals Connector (OSTI)

Over 1 year, private swimming pools in Australia will typically consume 1680 GWh of electricity, producing 2130 kt of CO2. Redesigning a pool's filtration system and using it more efficiently can reduce the energy use, and hence the CO2 production, by a significant amount. This paper describes experimental measurements carried out on a new design of pool pump system. Initial experiments using a variable frequency drive (VFD) with a standard, single phase pump/motor system have achieved energy savings of 40%. Utilising a VFD and a three phase pump/motor energy savings of 61% have been achieved, without degrading the system performance.

Z. Hameiri; T. Spooner; A.B. Sproul

2009-01-01T23:59:59.000Z

43

Managing variability in the IO performance of petascale storage systems.  

SciTech Connect

Significant challenges exist for achieving peak or even consistent levels of performance when using IO systems at scale. They stem from sharing IO system resources across the processes of single large-scale applications and/or multiple simultaneous programs causing internal and external interference, which in turn, causes substantial reductions in IO performance. This paper presents interference effects measurements for two different file systems at multiple supercomputing sites. These measurements motivate developing a 'managed' IO approach using adaptive algorithms varying the IO system workload based on current levels and use areas. An implementation of these methods deployed for the shared, general scratch storage system on Oak Ridge National Laboratory machines achieves higher overall performance and less variability in both a typical usage environment and with artificially introduced levels of 'noise'. The latter serving to clearly delineate and illustrate potential problems arising from shared system usage and the advantages derived from actively managing it.

Wolf, Matthew; Zheng, Fang; Klasky, Scott; Schwan, Karsten; Oldfield, Ron A.; Lofstead, Gerald Fredrick, II; Liu, Qing; Kordenbrock, Todd

2010-11-01T23:59:59.000Z

44

6 - Control systems for AC variable speed drives  

Science Journals Connector (OSTI)

Publisher Summary This chapter explores the control system, embodied in the control circuits. The simplest method of providing auxiliary power to the converter control circuits is from an auxiliary transformer connected to the mains. The primary need for current feedback in general purpose variable speed drives (VSDs) is inverter switching device protection. Various disadvantages of the vector controlled AC drive as compared to a DC drive are discussed in the chapter. The strategy of an AC vector control drive is to calculate the individual current vectors to eventually enable separate control of the flux current and the torque current under all speed and load conditions. The power circuit for a vector converter is almost identical to that used by a variable voltage variable frequency (VVVF) drive. High accuracy motor current feedback is also necessary to provide control of motor torque. DC bus current feedback is suitable for switching device protection and current limiting in most AC VSDs. Analog speed transducers are increasingly being replaced by digital devices, which are more compatible with modern digital control systems.

Malcolm Barnes

2003-01-01T23:59:59.000Z

45

Variable structure control of linear time-delay uncertain singular system  

Science Journals Connector (OSTI)

Synthesis and designing of variable structure controller for time-delay singular uncertain system are studied. Firstly, the system is decomposed into two low dimensional subsystems. Secondly, switching function and variable structure controller are ... Keywords: VSC, controller design, singular systems, switching function, time delay, uncertain systems, variable structure control

Jifeng Guo; Cunchen Gao

2009-04-01T23:59:59.000Z

46

Best Practices for Energy Efficient Cleanrooms Efficient HVAC Systems: Variable-Speed-Drive Chillers  

E-Print Network (OSTI)

LBNL-58636 Best Practices for Energy Efficient Cleanrooms Efficient HVAC Systems: Variable Efficient Cleanrooms Efficient HVAC Water Systems: Variable-Speed-Drive Chillers Tengfang Xu Contents HVAC.................................................................................................................................... 6 #12;HVAC Water Systems Variable-Speed-Drive Chillers Summary Cleanroom energy benchmarking data

47

Continuously proportional variable geometry turbocharger system and method of control  

SciTech Connect

This patent describes a system for performing closed loop control of a variable geometry turbocharger (VGT) utilized in an internal combustion engine. It comprises VGT actuator means for changing the geometric configuration of the VGT in response to an actuator control signal; sensor means for detecting selected engine operating parameters including a VGT actuator parameter and an engine intake manifold parameter, and generating output signals representative thereof; means for outputting a target VGT actuator parameter value and a target intake manifold parameter valve based on the values of selected sensor means output signals; means for determining whether the engine is in a steady state or a transient state of operation based on the values of selected sensor means output signals; and means for developing an actuator control signal based on one of the target parameter values as a function of the determined engine operating state.

Younessi, R.; Rini, G.T.

1992-06-23T23:59:59.000Z

48

Electromagnetic variable degrees of freedom actuator systems and methods  

DOE Patents (OSTI)

The present invention provides a variable reluctance actuator system and method that can be adapted for simultaneous rotation and translation of a moving element by applying a normal-direction magnetic flux on the moving element. In a beneficial example arrangement, the moving element includes a swing arm that carries a cutting tool at a set radius from an axis of rotation so as to produce a rotary fast tool servo that provides a tool motion in a direction substantially parallel to the surface-normal of a workpiece at the point of contact between the cutting tool and workpiece. An actuator rotates a swing arm such that a cutting tool moves toward and away from a mounted rotating workpiece in a controlled manner in order to machine the workpiece. Position sensors provide rotation and displacement information for a swing arm to a control system. A control system commands and coordinates motion of the fast tool servo with the motion of a spindle, rotating table, cross-feed slide, and in feed slide of a precision lathe.

Montesanti, Richard C. (Pleasanton, CA); Trumper, David L. (Plaistow, NH); Kirtley, Jr., James L. (Brookline, MA)

2009-02-17T23:59:59.000Z

49

Kinematic Reduction and Planning using Symmetry for a Variable Inertia Mechanical System  

E-Print Network (OSTI)

reduction [11][7] using the system's symmetry for a simple mechanical system called the Yaw model (see FigKinematic Reduction and Planning using Symmetry for a Variable Inertia Mechanical System Ravi present controllability results and kinematic reduction for a variable inertia mechanical system. We show

50

Sliding Mode Power Control of Variable Speed Wind Energy Conversion Systems  

E-Print Network (OSTI)

Sliding Mode Power Control of Variable Speed Wind Energy Conversion Systems B. Beltran, T. Ahmed power generation in variable speed wind energy conversion systems (VS-WECS). These systems have two variations. Index Terms--Wind energy conversion system, power generation control, sliding mode control

Boyer, Edmond

51

High Temperature Variable Conductance Heat Pipes for Radioisotope Stirling Systems  

SciTech Connect

In a Stirling radioisotope system, heat must continually be removed from the GPHS modules, to maintain the GPHS modules and surrounding insulation at acceptable temperatures. Normally, the Stirling converter provides this cooling. If the Stirling engine stops in the current system, the insulation is designed to spoil, preventing damage to the GPHS, but also ending the mission. An alkali-metal Variable Conductance Heat Pipe (VCHP) is under development to allow multiple stops and restarts of the Stirling engine. The status of the ongoing effort in developing this technology is presented in this paper. An earlier, preliminary design had a radiator outside the Advanced Stirling Radioisotope Generator (ASRG) casing, used NaK as the working fluid, and had the reservoir located on the cold side adapter flange. The revised design has an internal radiator inside the casing, with the reservoir embedded inside the insulation. A large set of advantages are offered by this new design. In addition to reducing the overall size and mass of the VCHP, simplicity, compactness and easiness in assembling the VCHP with the ASRG are significantly enhanced. Also, the permanently elevated temperatures of the entire VCHP allows the change of the working fluid from a binary compound (NaK) to single compound (Na). The latter, by its properties, allows higher performance and further mass reduction of the system. Preliminary design and analysis shows an acceptable peak temperature of the ASRG case of 140 deg. C while the heat losses caused by the addition of the VCHP are 1.8 W.

Tarau, Calin; Walker, Kara L.; Anderson, William G. [Advanced Cooling Technologies, Inc. 1046 New Holland Ave. Lancaster, PA 17601 (United States)

2009-03-16T23:59:59.000Z

52

Compact, electro-hydraulic, variable valve actuation system providing variable lift, timing and duration to enable high efficiency engine combustion control  

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

Discusses development of advanced variable valve actuation system to enable high efficiency combustion highlighting advances to improving system packaging while reducing cost

53

Energy Efficient Control of a Boosting System with Multiple Variable-Speed Pumps in Parallel  

E-Print Network (OSTI)

with multiple variable-speed pumps in parallel is to minimize the pump system energy consumption by controlEnergy Efficient Control of a Boosting System with Multiple Variable-Speed Pumps in Parallel Zhenyu. The experimental results show a huge potential to improve the energy efficiency of multi-pump systems using

Yang, Zhenyu

54

Analysis and Simulation of Mechanical Trains Driven by Variable Frequency Drive Systems.  

E-Print Network (OSTI)

??Induction motors and Variable Frequency Drives (VFDs) are widely used in industry to drive machinery trains. However, some mechanical trains driven by VFD-motor systems have… (more)

Han, Xu

2012-01-01T23:59:59.000Z

55

Production-Intent Lost-Motion Variable Valve Actuation Systems  

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

Variable valve actuation with on/off IEGR pre-bump is an enabling technology for HCCI, PCCI, LTC and other advanced combustion techniques, and designs for production-intent equipment have been developed

56

System and method of modulating electrical signals using photoconductive wide bandgap semiconductors as variable resistors  

DOE Patents (OSTI)

A system and method for producing modulated electrical signals. The system uses a variable resistor having a photoconductive wide bandgap semiconductor material construction whose conduction response to changes in amplitude of incident radiation is substantially linear throughout a non-saturation region to enable operation in non-avalanche mode. The system also includes a modulated radiation source, such as a modulated laser, for producing amplitude-modulated radiation with which to direct upon the variable resistor and modulate its conduction response. A voltage source and an output port, are both operably connected to the variable resistor so that an electrical signal may be produced at the output port by way of the variable resistor, either generated by activation of the variable resistor or propagating through the variable resistor. In this manner, the electrical signal is modulated by the variable resistor so as to have a waveform substantially similar to the amplitude-modulated radiation.

Harris, John Richardson; Caporaso, George J; Sampayan, Stephen E

2013-10-22T23:59:59.000Z

57

Variable Speed Drive (VSD) Applications in Dual-Duct Constant Volume Systems  

E-Print Network (OSTI)

Models have been developed for static pressure and potential supply fan energy savings by using variable speed drive (VSD) in dual-duct constant volume systems. Experiments have been performed using a full size dual-duct constant volume system...

Joo, I.; Liu, M.; Conger, K.; Wang, G.

2002-01-01T23:59:59.000Z

58

Control system and method for a power delivery system having a continuously variable ratio transmission  

DOE Patents (OSTI)

A control system and method for a power delivery system, such as in an automotive vehicle, having an engine coupled to a continuously variable ratio transmission (CVT). Totally independent control of engine and transmission enable the engine to precisely follow a desired operating characteristic, such as the ideal operating line for minimum fuel consumption. CVT ratio is controlled as a function of commanded power or torque and measured load, while engine fuel requirements (e.g., throttle position) are strictly a function of measured engine speed. Fuel requirements are therefore precisely adjusted in accordance with the ideal characteristic for any load placed on the engine.

Frank, Andrew A. (1034 Hillside Ave., Madison, WI 53705)

1984-01-01T23:59:59.000Z

59

AUTOMATIC VARIABLE VENTILATION CONTROL SYSTEMS BASED ON AIR QUALITY DETECTION  

E-Print Network (OSTI)

Control Systems Based on Air Quality Detection Isaac Turiel,HVAC CONTROL SYSTEM BASED ON AIR QUALITY SENSING To Zl)(lecontrol systems based on air quality detection Isaac Turiel,

Turiel, Isaac

2011-01-01T23:59:59.000Z

60

CIP methods for hyperbolic system with variable and discontinuous coefficient  

E-Print Network (OSTI)

We propose a multi-moment method for one-dimensional hyperbolic equations with smooth coefficient and piecewise constant coefficient. The method is entirely based on the backward characteristic method and uses the solution and its derivative as unknowns and cubic Hermite interpolation for each computational cell. The exact update formula for solution and its derivative is derived and used for an efficient time integration. At points of discontinuity of wave speed we define a piecewise cubic Hermite interpolation based on immersed interface method. The method is extended to the one-dimensional Maxwell's equations with variable material properties.

Ito, Kazufumi

2011-01-01T23:59:59.000Z

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


61

Numerical Analysis of a Cold Air Distribution System  

E-Print Network (OSTI)

Cold air distribution systems may reduce the operating energy consumption of air-conditioned air supply system and improve the outside air volume percentages and indoor air quality. However, indoor temperature patterns and velocity field are easily...

Zhu, L.; Li, R.; Yuan, D.

2006-01-01T23:59:59.000Z

62

A Method to Study the Effect of Renewable Resource Variability on Power System Dynamics  

E-Print Network (OSTI)

1 A Method to Study the Effect of Renewable Resource Variability on Power System Dynamics Yu reliance on renewable resources, such as wind or solar. It is well known that the integration proposes a set-theoretic method to assess the effect of variability associated with renewable-based elec

Liberzon, Daniel

63

Demonstration of a Variable Phase Turbine Power System for Low...  

Office of Environmental Management (EM)

turbine geothermal ORC system A Revolutionary Hybrid Thermodynamic Cycle for Bianary Geothermal Power Free Flow Energy (TRL 1 2 3 Component) - Design and Development of a...

64

Multifinger Penetration Rate and ROC Variability for Automatic Fingerprint Identification Systems  

Science Journals Connector (OSTI)

AFIS system design and performance is heavily impacted by data correlations and error rate variability both within and across individual fingerprint ... and left hands, as well as experimental penetration and bin...

James L. Wayman

2004-01-01T23:59:59.000Z

65

Analysis and Simulation of Mechanical Trains Driven by Variable Frequency Drive Systems  

E-Print Network (OSTI)

Induction motors and Variable Frequency Drives (VFDs) are widely used in industry to drive machinery trains. However, some mechanical trains driven by VFD-motor systems have encountered torsional vibration problems. This vibration can induce large...

Han, Xu

2012-02-14T23:59:59.000Z

66

Entanglement criteria and nonlocality for multimode continuous-variable systems RID B-8901-2008  

E-Print Network (OSTI)

We demonstrate how to efficiently derive a broad class of inequalities for entanglement detection in multimode continuous variable systems. The separability conditions are established from partial transposition (PT) in combination with several...

Sun, Qingqing; Nha, Hyunchul; Zubairy, M. Suhail

2009-01-01T23:59:59.000Z

67

Impact of the Variable Refrigerant Volume Air Conditioning System on Building Energy Efficiency  

E-Print Network (OSTI)

The application of the variable refrigerant volume multi-zone air conditioning systems has met with mixed results since the publication of the Design Standard for Energy Efficiency of Public Buildings. This paper analyzes the characteristics...

Zhu, H.

2006-01-01T23:59:59.000Z

68

Variable geometry exhaust manifold turbocharging system for an 8-cylinder marine diesel engine  

Science Journals Connector (OSTI)

The variable geometry exhaust manifold (VGEM) turbocharging system can realize the switch between two charging modes by the switching valve, and it can give a good performance both at the high load operation and ...

Lei Shi; Shaoming Wang; Kangyao Deng; Yi Cui

2012-06-01T23:59:59.000Z

69

Understanding Variability and Uncertainty of Photovoltaics for Integration with the Electric Power System  

E-Print Network (OSTI)

area of photovoltaic and other clean energy technologies.Energy recently hosted a day-long public workshop on the variability of photovoltaic (photovoltaic power plants into the utility system. Nicholas Miller is Director, Energy

Mills, Andrew

2010-01-01T23:59:59.000Z

70

Two-Stage Variable Compression Ratio (VCR) System to Increase Efficiency in Gasoline Powertrains  

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

Presents two-stage variable compression ratio mechanism realized by varying the connecting rod length, description of the system layout, working principle and expected fuel savings benefits when used in current and future gasoline engine concepts

71

Method and system to estimate variables in an integrated gasification combined cycle (IGCC) plant  

DOE Patents (OSTI)

System and method to estimate variables in an integrated gasification combined cycle (IGCC) plant are provided. The system includes a sensor suite to measure respective plant input and output variables. An extended Kalman filter (EKF) receives sensed plant input variables and includes a dynamic model to generate a plurality of plant state estimates and a covariance matrix for the state estimates. A preemptive-constraining processor is configured to preemptively constrain the state estimates and covariance matrix to be free of constraint violations. A measurement-correction processor may be configured to correct constrained state estimates and a constrained covariance matrix based on processing of sensed plant output variables. The measurement-correction processor is coupled to update the dynamic model with corrected state estimates and a corrected covariance matrix. The updated dynamic model may be configured to estimate values for at least one plant variable not originally sensed by the sensor suite.

Kumar, Aditya; Shi, Ruijie; Dokucu, Mustafa

2013-09-17T23:59:59.000Z

72

System for throttling and compensation for variable feedstock properties  

DOE Patents (OSTI)

Apparatus is shown for adjusting the feed rate of pulverized feed material into a pressurized container. The apparatus also has utility for compensating for variations in the permeability of the feed material. A rotor that includes sprues with provision for controlling the pressure distribution along the sprues is located within the pressurized container. The rotor hub is connected to a drive means and a material supply means which extend through the wall of the container. A line for controlling pressure along the sprues by gas injection is connected to a chamber between sections of the sprue for controlling gas pressure at that point. The gas pressure control line is connected to a pressurized gas source and a control system external to the rotor.

Meyer, John W. (Palo Alto, CA)

1981-01-01T23:59:59.000Z

73

The RenewElec Project: Variable Renewable Energy and the Power System  

SciTech Connect

Variable energy resources, such as wind power, now produce about 4% of U.S. electricity. They can play a significantly expanded role if the U.S. adopts a systems approach that considers affordability, security and reliability. Reaching a 20-30% renewable portfolio standard goal is possible, but not without changes in the management and regulation of the power system, including accurately assessing and preparing for the operational effects of renewable generation. The RenewElec project will help the nation make the transition to the use of significant amounts of electric generation from variable and intermittent sources of renewable power.

Apt, Jay

2014-02-14T23:59:59.000Z

74

Application of multi-variable control for automatic frequency controller of HVDC transmission system  

SciTech Connect

In an HVDC transmission system that links two ac power systems, the automatic frequency controller (AFC) calculates power to be interchanged between the two ac systems according to their frequencies thereby improving the frequency characteristics of the two power systems. This paper introduces a newly developed dc AFC system, which applies a multi-variable control to the dc system-based frequency control. It is capable of controlling the frequencies of the two ac systems optimally while maintaining their stability. This system was developed for one of Japan's HVDC transmission facilities and produced good results in a combined test using a power system simulator. The field installation will be completed in March 1993, when the AFC system will enter service.

Sanpei, Masatoshi (Electric Power Development Co., Tokyo (Japan)); Kakehi, Atsuyuki; Takeda, Hideo (Toshiba Corp., Tokyo (Japan))

1994-04-01T23:59:59.000Z

75

Impact of Wind Generation Variability on Voltage Profile of Radial Power Systems  

Science Journals Connector (OSTI)

This paper provides the results of a study conducted to assess the impacts of the "wind generation variability" on the voltage profile in a small-scale radial power system. The power network has been modeled using one of the well-known simulation programs ... Keywords: Wind Generation, Voltage Profile, Power Grids, Voltage Impacts, Minimum Singular Value, SSV index

M. O. Alruwaili; M. Y. Vaziri; S. Vadhva; S. Vaziri

2013-04-01T23:59:59.000Z

76

Global Sensitivity Analysis: a tool to analyse LCA variability of energy systems  

E-Print Network (OSTI)

Global Sensitivity Analysis: a tool to analyse LCA variability of energy systems Pierryves Padey1 been widely assessed over the past decades, in particular with the LCA approach. Several literature makers to consider LCA as an inconclusive method [2]. Improving the understanding of the LCA results

Paris-Sud XI, Université de

77

Modelled and observed variability of the atmospheric circulation the Peruvian Current System: 2000-2005  

E-Print Network (OSTI)

on the characteristics of the local equatorward atmospheric circulation. Resolving the mesoscale variability of the heat Mesoscale Model (MM5) and Weather Research and Forecasting (WRF) that were run over the Peruvian Current System (PCS) [0N-19°S; 83°W-68°W] from November 2000- October 2005. Wind data as derived from

78

Boussinesq systems in two space dimensions over a variable bottom for the generation and propagation of tsunami waves  

E-Print Network (OSTI)

Boussinesq systems in two space dimensions over a variable bottom for the generation.R.T.H., P.O. Box 1527, 71110 Heraklion, Greece Abstract Considered here are Boussinesq systems of equations of surface water wave theory over a variable bottom. A simplified such Boussinesq system is derived

Paris-Sud XI, Université de

79

Investigation on multi-variable decoupled temperature control system for enamelling machine with heated air circulation  

SciTech Connect

A lots of problems may occur frequently when controlling the temperature of the enamelling machine oven in the real industrial process, such as multi-variable coupled problem. an experimental rig with triple inputs and triple outputs was devised and a simulation modeling was established accordingly in this study,. the temperature control system based on the feedforward compensation algorithm was proposed. Experimental results have shown that the system is of high efficiency, good stability and promising application.

Li, Yang; Qin, Le; Zou, Shipeng; Long, Shijun [School of Information Engineering, Guangdong University of Technology, Guangzhou, 510006 (China)

2014-04-11T23:59:59.000Z

80

Performance of thermal distribution systems in large commercial buildings  

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

Performance of thermal distribution systems in large commercial buildings Performance of thermal distribution systems in large commercial buildings Title Performance of thermal distribution systems in large commercial buildings Publication Type Journal Article LBNL Report Number LBNL-44331 Year of Publication 2002 Authors Xu, Tengfang T., François Rémi Carrié, Darryl J. Dickerhoff, William J. Fisk, Jennifer A. McWilliams, Duo Wang, and Mark P. Modera Journal Energy and Buildings Volume 34 Start Page Chapter Pagination 215-226 Abstract This paper presents major findings of a field study on the performance of five thermal distribution systems in four large commercial buildings. The five systems studied are typical single-duct or dual-duct constant air volume (CAV) systems and variable air volume (VAV) systems, each of which serves an office building or a retail building with floor area over 2,000 m2. The air leakage from ducts are reported in terms of effective leakage area (ELA) at 25 Pa reference pressure, the ASHRAE-defined duct leakage class, and air leakage ratios. The specific ELAs ranged from 0.7 to 12.9 cm2 per m2 of duct surface area, and from 0.1 to 7.7 cm2 per square meter of floor area served. The leakage classes ranged from 34 to 757 for the five systems and systems sections tested. The air leakage ratios are estimated to be up to one-third of the fan- supplied airflow in the constant-air-volume systems. The specific ELAs and leakage classes indicate that air leakage in large commercial duct systems varies significantly from system to system, and from system section to system section even within the same thermal distribution system. The duct systems measured are much leakier than the ductwork specified as "unsealed ducts" by ASHRAE. Energy losses from supply ducts by conduction (including convection and radiation) are found to be significant, on the scale similar to the losses induced by air leakage in the duct systems. The energy losses induced by leakage and conduction suggest that there are significant energy-savings potentials from duct-sealing and insulation practice in large commercial buildings

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


81

Variable interval time/temperature (VITT) defrost-control-system evaluation  

SciTech Connect

Two variable-interval-time/temperature (VITT) heat pump defrost control systems are analyzed to determine if systems manufactured by Honeywell and Ranco qualify for credit for heat pumps with demand defrost control. The operation of the systems is described. VITT controls are not demand defrost control systems but utilize demand defrost control as backup systems in most Ranco models and all Honeywell models. The evaluations and results, intended to provide DOE information in making its determinations regarding credits for the control systems are discussed. The evaluation methodology utilizes a modified version of the Heat Pump Seasonal Performance Model (HPSPM) and the important modifications are discussed in Appendix A. Appendix B contains a detailed listing and discussion of the HPSPM output. (MCW)

None

1980-08-12T23:59:59.000Z

82

HVAC systems in the current stock of U. S. K-12 schools. Final report, May 91-Mar 92  

SciTech Connect

The report summarizes information on heating, ventilating, and air-conditioning (HVAC) systems commonly found in U.S. school buildings and the effect that operating these systems has on indoor radon levels. The report describes the ability of various HVAC systems to pressurize and ventilate classroom spaces, how they operate, and how they are controlled. Some information is given to compare systems from the standpoint of energy use, cost, and their ability to maintain stable levels of static pressure in classrooms and/or to adequately ventilate the spaces. There do not appear to be any well defined trends in types of HVAC systems involved in current school building construction and modification. Systems looked at include those using reheat and/or mixing, unit ventilators (UVs), and two-fan, dual-duct variable air volume (VAV) systems.

Parker, J.D.

1992-07-01T23:59:59.000Z

83

Quantum hacking of a continuous-variable quantum-key-distribution system using a wavelength attack  

Science Journals Connector (OSTI)

The security proofs of continuous-variable quantum key distribution are based on the assumptions that the eavesdropper can neither act on the local oscillator nor control Bob's beam splitter. These assumptions may be invalid in practice due to potential imperfections in the implementations of such protocols. In this paper, we consider the problem of transmitting the local oscillator in a public channel and propose a wavelength attack which allows the eavesdropper to control the intensity transmission of Bob's beam splitter by switching the wavelength of the input light. Specifically we target continuous-variable quantum key distribution systems that use the heterodyne detection protocol using either direct or reverse reconciliation. Our attack is proved to be feasible and renders all of the final keys shared between the legitimate parties insecure, even if they have monitored the intensity of the local oscillator. To prevent our attack on commercial systems, a simple wavelength filter should be randomly added before performing monitoring detection.

Jing-Zheng Huang; Christian Weedbrook; Zhen-Qiang Yin; Shuang Wang; Hong-Wei Li; Wei Chen; Guang-Can Guo; Zheng-Fu Han

2013-06-24T23:59:59.000Z

84

Quantum Hacking on Continuous-Variable Quantum Key Distribution System using a Wavelength Attack  

E-Print Network (OSTI)

The security proofs of continuous-variable quantum key distribution are based on the assumptions that the eavesdropper can neither act on the local oscillator nor control Bob's beam splitter. These assumptions may be invalid in practice due to potential imperfections in the implementations of such protocols. In this paper, we consider the problem of transmitting the local oscillator in a public channel and propose a wavelength attack which can allow the eavesdropper to control the intensity transmission of Bob's beam splitter by switching the wavelength of the input light. Specifically we target continuous-variable quantum key distribution systems that use the heterodyne detection protocol using either direct or reverse reconciliation. Our attack is proved to be feasible and renders all of the final key shared between the legitimate parties insecure, even if they have monitored the intensity of the local oscillator. To prevent our attack on commercial systems, a simple wavelength filter should be added before performing the monitoring detection.

Jing-Zheng Huang; Christian Weedbrook; Zhen-Qiang Yin; Shuang Wang; Hong-Wei Li; Wei Chen; Guang-Can Guo; Zheng-Fu Han

2013-02-01T23:59:59.000Z

85

Demonstration of a Variable Phase Turbine Power System for Low Temperature Geothermal Resources  

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

Project objectives: Demonstrate a 1 megawatt Variable Phase Turbine and Variable Phase Cycle with low temperature brine.

86

Connecting Atlantic temperature variability and biological cycling in two earth system models  

Science Journals Connector (OSTI)

Abstract Connections between the interdecadal variability in North Atlantic temperatures and biological cycling have been widely hypothesized. However, it is unclear whether such connections are due to small changes in basin-averaged temperatures indicated by the Atlantic Multidecadal Oscillation (AMO) Index, or whether both biological cycling and the AMO index are causally linked to changes in the Atlantic Meridional Overturning Circulation (AMOC). We examine interdecadal variability in the annual and month-by-month diatom biomass in two Earth System Models with the same formulations of atmospheric, land, sea ice and ocean biogeochemical dynamics but different formulations of ocean physics and thus different AMOC structures and variability. In the isopycnal-layered ESM2G, strong interdecadal changes in surface salinity associated with changes in AMOC produce spatially heterogeneous variability in convection, nutrient supply and thus diatom biomass. These changes also produce changes in ice cover, shortwave absorption and temperature and hence the AMO Index. Off West Greenland, these changes are consistent with observed changes in fisheries and support climate as a causal driver. In the level-coordinate ESM2M, nutrient supply is much higher and interdecadal changes in diatom biomass are much smaller in amplitude and not strongly linked to the AMO index.

Anand Gnanadesikan; John P. Dunne; Rym Msadek

2014-01-01T23:59:59.000Z

87

Variable Structure Control of a Doubly Fed Induction Generator for Wind Energy Conversion Systems  

Science Journals Connector (OSTI)

Abstract This paper presents the powers control of a variable speed wind turbine (WT) device based on a doubly fed induction generator (DFIG). Indeed, to increase the efficiency of the WT system, a robust variable structure control has been applied. DFIG has been previously presented in several works with diverse control diagrams using generally conventional PI controllers. Nevertheless, this type of controllers does not sufficiently handle some of WT resource characteristics such as wind fluctuations effects. Indeed, these can reduce WT performances. Furthermore, DFIG parameter variations should be accounted for. In this context, this paper proposes a high-order sliding mode to control the WT DFIG. Simulation results show that the proposed approach presents attractive features such as chattering-free behavior, good response to speed variations and robustness against machine parameter variations compared to the conventional first order sliding mode technique and even fuzzy sliding mode one.

E. Bounadja; A. Djahbar; Z. Boudjema

2014-01-01T23:59:59.000Z

88

Comparison of energy efficiency between variable refrigerant flow systems and ground source heat pump systems  

E-Print Network (OSTI)

tool for geothermal water loop heat pump systems, 9thInternational IEA Heat Pump Conference, Zürich, Switzerland,Performance of ground source heat pump system in a near-zero

Hong, Tainzhen

2010-01-01T23:59:59.000Z

89

Demonstration of a Variable Phase Turbine Power System for Low Temperature Geothermal Resources  

SciTech Connect

A variable phase turbine assembly will be designed and manufactured having a turbine, operable with transcritical, two-phase or vapor flow, and a generator – on the same shaft supported by process lubricated bearings. The assembly will be hermetically sealed and the generator cooled by the refrigerant. A compact plate-fin heat exchanger or tube and shell heat exchanger will be used to transfer heat from the geothermal fluid to the refrigerant. The demonstration turbine will be operated separately with two-phase flow and with vapor flow to demonstrate performance and applicability to the entire range of low temperature geothermal resources. The vapor leaving the turbine is condensed in a plate-fin refrigerant condenser. The heat exchanger, variable phase turbine assembly and condenser are all mounted on single skids to enable factory assembly and checkout and minimize installation costs. The system will be demonstrated using low temperature (237F) well flow from an existing large geothermal field. The net power generated, 1 megawatt, will be fed into the existing power system at the demonstration site. The system will demonstrate reliable generation of inexpensive power from low temperature resources. The system will be designed for mass manufacturing and factory assembly and should cost less than $1,200/kWe installed, when manufactured in large quantities. The estimated cost of power for 300F resources is predicted to be less than 5 cents/kWh. This should enable a substantial increase in power generated from low temperature geothermal resources.

Hays, Lance G

2014-07-07T23:59:59.000Z

90

The Coordinated Control of a Central Air Conditioning System Based on Variable Chilled Water Temperature and Variable Chilled Water Flow  

E-Print Network (OSTI)

At present, regulation of water flow by means of pump frequency conversion is one of the major methods for power-saving in central air conditioning systems. In this article, optimization regulation for central air conditioning system on the basis...

Liu, J.; Mai, Y.; Liu, X.

2006-01-01T23:59:59.000Z

91

Comparison of energy efficiency between variable refrigerant flow systems and ground source heat pump systems  

E-Print Network (OSTI)

as other types of air source heat pumps, VRF systems needconventional packaged air source heat pumps. Typical GSHPis basically an air source heat pump), especially when the

Hong, Tainzhen

2010-01-01T23:59:59.000Z

92

Airflow regulation in variable-speed systems for residential HVAC applications  

SciTech Connect

In the majority of heating, ventilating, and air-conditioning (HVAC) systems, air is the final medium for adding or extracting heat from or to the space to be air conditioned. Air is heated by passing it over a heat transfer device called a coil, which is a heat exchanger with air on the outside and the primary heating/cooling medium (water, steam, electricity, refrigerant, etc.) on the inside. One of the major factors determining heat transfer is the airflow rate, which can be controlled by mechanical means or by controlling the speed of the fan. Centrifugal fans driven by single-speed induction motors traditionally have been used in the JVAC industry but have an airflow characteristic that depends on the static pressure seen by the system. Variable-speed systems are starting to emerge as a strong alternative to traditional systems because of their ability to match the demand of the air-conditioned space, resulting in higher efficiencies and higher comfort. System efficiency can be improved by constraining the range of airflows provided by the fan or blower system in response to system pressure, that is, by controlling the airflow over the heat exchanger. This paper presents a method to regulate airflow independent of the static pressure and without the need for airflow sensors.

Becerra, R.C.; Beifus, B.L. [General Electric Co., Fort Wayne, IN (United States)

1996-11-01T23:59:59.000Z

93

Temporal and spatial variability of wind resources in the United States as derived from the Climate Forecast System Reanalysis  

Science Journals Connector (OSTI)

This study examines the spatial and temporal variability of wind speed at 80 m above ground (the average hub height of most modern wind turbines) in the contiguous United States using Climate Forecast System Reanalysis (CFSR) data from 1979 to ...

Lejiang Yu; Shiyuan Zhong; Xindi Bian; Warren E. Heilman

94

A nuclear wind/solar oil-shale system for variable electricity and liquid fuels production  

SciTech Connect

The recoverable reserves of oil shale in the United States exceed the total quantity of oil produced to date worldwide. Oil shale contains no oil, rather it contains kerogen which when heated decomposes into oil, gases, and a carbon char. The energy required to heat the kerogen-containing rock to produce the oil is about a quarter of the energy value of the recovered products. If fossil fuels are burned to supply this energy, the greenhouse gas releases are large relative to producing gasoline and diesel from crude oil. The oil shale can be heated underground with steam from nuclear reactors leaving the carbon char underground - a form of carbon sequestration. Because the thermal conductivity of the oil shale is low, the heating process takes months to years. This process characteristic in a system where the reactor dominates the capital costs creates the option to operate the nuclear reactor at base load while providing variable electricity to meet peak electricity demand and heat for the shale oil at times of low electricity demand. This, in turn, may enable the large scale use of renewables such as wind and solar for electricity production because the base-load nuclear plants can provide lower-cost variable backup electricity. Nuclear shale oil may reduce the greenhouse gas releases from using gasoline and diesel in half relative to gasoline and diesel produced from conventional oil. The variable electricity replaces electricity that would have been produced by fossil plants. The carbon credits from replacing fossil fuels for variable electricity production, if assigned to shale oil production, results in a carbon footprint from burning gasoline or diesel from shale oil that may half that of conventional crude oil. The U.S. imports about 10 million barrels of oil per day at a cost of a billion dollars per day. It would require about 200 GW of high-temperature nuclear heat to recover this quantity of shale oil - about two-thirds the thermal output of existing nuclear reactors in the United States. With the added variable electricity production to enable renewables, additional nuclear capacity would be required. (authors)

Forsberg, C. [Massachusetts Inst. of Technology, 77 Massachusetts Ave., Cambridge, MA 012139 (United States)

2012-07-01T23:59:59.000Z

95

Optimal control for variable-speed wind generation systems using General Regression Neural Network  

Science Journals Connector (OSTI)

Abstract An induction generator (IG) speed drive with the application of an optimal controller and a proposed General Regression Neural Network (GRNN) controller is introduced in this paper. Grid connected wind energy conversion system (WECS) present interesting control demands, due to the intrinsic nonlinear characteristic of wind mills and electric generators. The GRNN with adaptive ant colony optimization (AACO) torque compensation is feed-forward to increase the robustness of the wind driven induction generator system. An optimal control loop for the wind power system is designed. The optimality of the whole system is defined in relation with the trade-off between the wind energy conversion maximization and the minimization of the induction generator torque variation that is responsible for the frequency fluctuations. This is achieved by using a combined optimization criterion, resulting in a LQ tracking problem with an infinite horizon and a measurable exogenous variable (wind speed). The proposed controller is designed to drive the turbine speed to extract maximum power from the wind and adjust to the power regulation.

Chih-Ming Hong; Fu-Sheng Cheng; Chiung-Hsing Chen

2014-01-01T23:59:59.000Z

96

Probabilistic Approach to Quantifying the Contribution of Variable Generation and Transmission to System Reliability: Preprint  

SciTech Connect

The increasing electrical load served by variable generation (VG), such as wind and solar energy, in the United States and many other countries has stimulated an interesting line of research to better quantify the capacity value of these resources. Methods applied traditionally to thermal units based on their average outage rates do not apply to VG because of their uncertain and non-dispatchable nature. The North American Electric Reliability Corporation's Integration of Variable Generation Task Force recently released a report that highlighted the need to develop and benchmark underlying loss-of-load expectation and related metrics that reasonably and fairly calculate the contribution to planning reserves, or capacity value, of solar and wind power. As the fraction of generation coming from VG becomes more significant, their estimated capacity value will have a larger impact on system planning. In this paper, we provide a method to include VG in traditional probabilistic-based adequacy methods. This method has been implemented in the Renewable Energy Probabilistic Resource Assessment tool developed at the National Renewable Energy Laboratory. Through an example based on the U.S. Western Interconnection, this method is applied to assess the effect that transmission can have on resource adequacy. We also analyze the interactions between available transmission and capacity value for VG.

Ibanez, E.; Milligan, M.

2012-09-01T23:59:59.000Z

97

Validation of a new control system for Elekta accelerators facilitating continuously variable dose rate  

SciTech Connect

Purpose: Elekta accelerators controlled by the current clinically used accelerator control system, Desktop 7.01 (D7), uses binned variable dose rate (BVDR) for volumetric modulated arc therapy (VMAT). The next version of the treatment control system (Integrity) supports continuously variable dose rate (CVDR) as well as BVDR. Using CVDR opposed to BVDR for VMAT has the potential of reducing the treatment time but may lead to lower dosimetric accuracy due to faster moving accelerator parts. Using D7 and a test version of Integrity, differences in ability to control the accelerator, treatment efficiency, and dosimetric accuracy between the two systems were investigated. Methods: Single parameter tests were designed to expose differences in the way the two systems control the movements of the accelerator. In these tests, either the jaws, multi leaf collimators (MLCs), or gantry moved at constant speed while the dose rate was changed in discrete steps. The positional errors of the moving component and dose rate were recorded using the control systems with a sampling frequency of 4 Hz. The clinical applicability of Integrity was tested using 15 clinically used VMAT plans (5 prostate, 5 H and N, and 5 lung) generated by the SmartArc algorithm in PINNACLE. The treatment time was measured from beam-on to beam-off and the accuracy of the dose delivery was assessed by comparing DELTA4 measurements and PINNACLE calculated doses using gamma evaluation. Results: The single parameter tests showed that Integrity had an improved feedback between gantry motion and dose rate at the slight expense of MLC control compared to D7. The single parameter test did not reveal any significant differences in the control of either jaws or backup jaws between the two systems. These differences in gantry and MLC control together with the use of CVDR gives a smoother Integrity VMAT delivery compared to D7 with less abrupt changes in accelerator motion. Gamma evaluation (2% of 2 Gy and 2 mm) of the calculated doses and DELTA4 measured doses corrected for systematic errors showed an average pass rate of more than 97.8% for both D7, Integrity BVDR, and Integrity CVDR deliveries. Direct comparisons between the measured doses using strict gamma criteria of 0.5% and 0.5 mm showed excellent agreement between D7 and Integrity delivered doses with average pass rates above 95.7%. Finally, the Integrity control system resulted in a significant 35% (55 {+-} 13 s) reduction in treatment time, on average. Conclusions: Single parameter tests showed that the two control systems differed in their feedback loops between MLC, gantry, and dose rate. These differences made the VMAT deliveries more smooth using the new Integrity treatment control system, compared to the current Desktop 7.01. Together with the use of CVDR, which results in less abrupt changes in dose rate, this further increases the smoothness of the delivery. The use of CVDR for VMAT with the Integrity desktop results in a significant reduction in treatment time compared to BVDR with an average reduction of 35%. This decrease in delivery time was achieved without compromising the dosimetric accuracy.

Bertelsen, Anders; Lorenzen, Ebbe L.; Brink, Carsten [Institute of Clinical Research, University of Southern Denmark, Odense DK-5000, Denmark and Laboratory of Radiation Physics, Odense University Hospital, Odense DK-5000 (Denmark)

2011-08-15T23:59:59.000Z

98

Understanding Variability and Uncertainty of Photovoltaics for Integration with the Electric Power System  

E-Print Network (OSTI)

variability of photovoltaic (PV) plants to avoid unnecessaryhowever, occurs within PV plants. The degree of smoothingof photovoltaic (PV) plants. The workshop brought together

Mills, Andrew

2010-01-01T23:59:59.000Z

99

The systemic velocities of four long-period cataclysmic variable stars  

E-Print Network (OSTI)

Although a large number of orbital periods of cataclysmic variable stars (CVs) have been measured, comparison of period and luminosity distributions with evolutionary theory is affected by strong selection effects. A test has been discovered which is independent of these selection effects and is based upon the kinematics of CVs (Kolb & Stehle, 1996). If the standard models of evolution are correct then long-period (P_orb > 5 hrs) CVs should be typically less than 1.5 Gyr old, and their line-of-sight velocity dispersion ($\\sigma_\\gamma$) should be small. We present results from a pilot study which indicate that this postulate is indeed true. Four long-period dwarf novae (EM Cyg, V426 Oph, SS Cyg and AH Her) were observed over a complete orbit, in order that accurate radial velocities be obtained. We find values of -1.7, 5.4, 15.4 and 1.8 km/s with uncertainties of order 3 km/s, referred to the dynamical Local Standard of Rest (LSR), leading to a dispersion of ~ 8 km/s. Calculation of a 95 per cent confidence interval gives the result 4 < \\sigma_\\gamma < 28 km/s compared to a prediction of 15 km/s. We also have an improved determination of mass donor spectral type, K_2 and q for the four systems.

R. C. North; T. R. Marsh; U. Kolb; V. S. Dhillon; C. K. J. Moran

2002-01-31T23:59:59.000Z

100

Modeling without categorical variables : a mixed-integer nonlinear program for the optimization of thermal insulation systems.  

SciTech Connect

Optimal design applications are often modeled by using categorical variables to express discrete design decisions, such as material types. A disadvantage of using categorical variables is the lack of continuous relaxations, which precludes the use of modern integer programming techniques. We show how to express categorical variables with standard integer modeling techniques, and we illustrate this approach on a load-bearing thermal insulation system. The system consists of a number of insulators of different materials and intercepts that minimize the heat flow from a hot surface to a cold surface. Our new model allows us to employ black-box modeling languages and solvers and illustrates the interplay between integer and nonlinear modeling techniques. We present numerical experience that illustrates the advantage of the standard integer model.

Abhishek, K.; Leyffer, S.; Linderoth, J. T.; Mathematics and Computer Science; Lehigh Univ.

2010-06-01T23:59:59.000Z

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


101

The pulsation, temperatures and metallicities of Mira and semiregular variables in different stellar systems  

Science Journals Connector (OSTI)

......extension observed in the red, and the combined data...ZA I Large-amplitude red variables. In the present...excluded are supergiant red variables. 1996RAS Royal...licity dependence (Wood 1990), although no evidence...present paper reinvesti- gates this relation, and it......

M. W. Feast

1996-01-01T23:59:59.000Z

102

Module Development and Simulation of the Variable Refrigerant Flow Air Conditioning System under Cooling Conditions in Energyplus  

E-Print Network (OSTI)

As a high-efficiency air conditioning scheme, the variable refrigerant flow (VRF) air-conditioning system is finding its way into medium-sized office buildings. Based on a generic dynamic building energy simulation environment, EnergyPlus, a new...

Zhou, Y.; Wu, J.; Wang, R.; Shiochi, S.

2006-01-01T23:59:59.000Z

103

Energy-Saving Design for Pressure Difference Control in Variable Flow Air Conditioning Systems  

E-Print Network (OSTI)

Zhang Senior Engineer Postgraduate Wuhan Architectural Design Institute, Wuhan, China, 430014 Chenyh918@263.net Abstract: This paper analyzes energy-saving design for pressure-difference control in a variable flow air...

Chen, Y.; Zhang, Z.

2006-01-01T23:59:59.000Z

104

Mechanisms of Decadal Arctic Climate Variability in the Community Climate System Model, Version 2 (CCSM2)  

Science Journals Connector (OSTI)

Several mechanisms have been proposed to explain natural climate variability in the Arctic. These include processes related to the influence of the North Atlantic Oscillation/Arctic Oscillation (NAO/AO), anticyclonic/cyclonic regimes, changes in ...

Hugues Goosse; Marika M. Holland

2005-09-01T23:59:59.000Z

105

Tests with a line-commutated converter as a variable inductive load on the Bonneville Power Administration transmission system  

SciTech Connect

A twelve-pulse, line-commutated converter, with a steady-state rating of 2.5 kV and 5.5 kA, formerly used for charging and discharging a superconducting magnet, was reconfigured as a static reactive power load. Tests staged at the Tacoma, WA, substation of the Bonneville Power Administration (BPA) revealed that the converter could be used as a variable inductive load, provided a stable current controller was installed. The unit was modulated as a variable VAR load following a sinusoidal VAR demand signal with an amplitude up to 14.8 MVAR. The total losses at maximum VAR output were 370 kW. This paper explains the necessary modifications of the converter to operate as a variable reactive load. Measured current waveshapes are analyzed. The effects of such a load on the BPA transmission system are presented.

Boenig, H.J.; Hauer, J.F.; Nielsen, R.G.

1986-01-01T23:59:59.000Z

106

Ota City : characterizing output variability from 553 homes with residential PV systems on a distribution feeder.  

SciTech Connect

This report describes in-depth analysis of photovoltaic (PV) output variability in a high-penetration residential PV installation in the Pal Town neighborhood of Ota City, Japan. Pal Town is a unique test bed of high-penetration PV deployment. A total of 553 homes (approximately 80% of the neighborhood) have grid-connected PV totaling over 2 MW, and all are on a common distribution line. Power output at each house and irradiance at several locations were measured once per second in 2006 and 2007. Analysis of the Ota City data allowed for detailed characterization of distributed PV output variability and a better understanding of how variability scales spatially and temporally. For a highly variable test day, extreme power ramp rates (defined as the 99th percentile) were found to initially decrease with an increase in the number of houses at all timescales, but the reduction became negligible after a certain number of houses. Wavelet analysis resolved the variability reduction due to geographic diversity at various timescales, and the effect of geographic smoothing was found to be much more significant at shorter timescales.

Stein, Joshua S.; Miyamoto, Yusuke (Kandenko, Ibaraki, Japan); Nakashima, Eichi (Kandenko, Ibaraki, Japan); Lave, Matthew

2011-11-01T23:59:59.000Z

107

Orbital and stochastic far-ultraviolet variability in the nova-like system V3885 Sgr  

Science Journals Connector (OSTI)

......line depth and velocity changes as a function...V3885 Sgr|stars: mass-loss|novae...variables|stars: winds, outflows| 1INTRODUCTION...sign marks the velocity of the mass gainer, and the...The gaps in the velocity maps correspond to the......

R. K. Prinja; K. S. Long; M. T. Richards; D. K. Witherick; L. W. Peck

2012-02-01T23:59:59.000Z

108

Interannual variability in chlorophyll concentrations in the Humboldt and California Current Systems  

E-Print Network (OSTI)

are explored through correlations to local upwelling anomalies and three indices of Pacific Ocean basin the Southern California Bight and off Peru, where circulation and/or chlorophyll phenology differ from on this relatively well docu- mented seasonality is strong interannual variability imposed from basin

Thomas, Andrew

109

Performance Variability  

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

Variability Variability of Highly Parallel Architectures William T.C. Kramer 1 and Clint Ryan 2 1 Department of Computing Sciences, University of California at Berkeley and the National Energy Research Scientific Computing Center, Lawrence Berkeley National Laboratory 2 Department of Computing Sciences, University of California at Berkeley Abstract. The design and evaluation of high performance computers has concentrated on increasing computational speed for applications. This performance is often measured on a well configured dedicated sys- tem to show the best case. In the real environment, resources are not always dedicated to a single task, and systems run tasks that may influ- ence each other, so run times vary, sometimes to an unreasonably large extent. This paper explores the amount of variation seen across four large distributed memory systems in a systematic manner. It then

110

Response of piping system with semi-active variable friction dampers under tri-directional seismic excitation  

Science Journals Connector (OSTI)

Seismic loads on piping system due to earthquakes can cause excessive vibrations, which can lead to serious instability resulting in damage or complete failure. In this paper, semi-active variable friction dampers (SAVFDs) have been studied to mitigate seismic response and vibration control of piping system used in the process industries, fossil and fissile fuel power plant. A study is also conducted on the performance of control due to variation in gain multiplier (?) in the present control law, which plays an important role in the present control algorithm of the damper. The effectiveness of the SAVFD in terms of reduction in the responses, namely, displacements, accelerations and base shear of the piping system is investigated by comparing uncontrolled responses under four artificial earthquake motions with increasing amplitudes. The analytical results demonstrate that the SAVFDs under particular optimum parameters are very effective and practically implementable for the seismic response mitigation, vibration control and seismic requalification of piping systems.

Praveen Kumar; R.S. Jangid; G.R. Reddy

2013-01-01T23:59:59.000Z

111

The method of dynamic projection operators in the theory of hyperbolic systems of partial differential equations with variable coefficients  

E-Print Network (OSTI)

We consider a generalization of the projecting operators method for the case of Cauchy problem for systems of 1D evolution differential equations of first order with variable coefficients. It is supposed that the coefficients dependence on the only variable x is weak, that is described by a small parameter introduction. Such problem corresponds, for example, to the case of wave propagation in a weakly inhomogeneous medium. As an example, we specify the problem to adiabatic acoustics. For the Cauchy problem, to fix unidirectional modes, the projection operators are constructed. The method of successive approximations (perturbation theory) is developed and based on pseudodifferential operators theory. The application of these projection operators allows to obtain approximate evolution equations corresponding to the separated directed waves.

Sergey Leble; Irina Vereshchagina

2014-03-30T23:59:59.000Z

112

Two-Dimensional Hybrid Spatial Audio Systems with User Variable Controls of Sound Source Attributes  

Science Journals Connector (OSTI)

This paper presents two novel hybrid spatial audio systems demonstrated for use in two-dimensional ... further creative freedom to a composer, sound engineer or sound designer. The systems are principally ... bas...

Martin J. Morrell; Joshua D. Reiss

2013-01-01T23:59:59.000Z

113

Variable current-voltage TPV device for use in a thermophotovoltaic energy conversion system  

DOE Patents (OSTI)

A front-side or back-side illuminated variable current-voltage thermophotovoltaic device comprises a support substrate; isolation layers disposed on the support substrate; a plurality of cells disposed on the isolation layers, each of the cells including a base layer and an emitter layer; an insulating member disposed between each of the cells configured to isolate each cell from adjacent cells; an ohmic contact configured to connect each cell to another cell in series; and a spectral control device disposed on top of the cells and/or on the bottom surface of the support substrate.

Charache, Greg W. (Clifton Park, NY); Baldasaro, Paul F. (Clifton Park, NY); Campbell, Brian C. (Scotia, NY)

2000-01-01T23:59:59.000Z

114

Coping with Variability in Model-Based Systems Engineering: An Experience in Green Energy  

E-Print Network (OSTI)

ML, a leading MBSE language, for developing a product line of wind turbine systems used for the generationML and how it has been applied to an ongoing project on wind turbine systems for the generation {strujillo, xmendialdua, jdesosa}@ikerlan.es 2 Alstom Wind Power. Barcelona, Spain {jose

Egyed, Alexander

115

An Adaptive Vision System for Tracking Soccer Players from Variable Camera Settings  

E-Print Network (OSTI)

of soccer players taped on video. The system per- forms well in a multitude of application scenarios because these submodules is adding to both the reliability and the efficiency of the overall system. 1 Introduction The automatic observation of team-sport games is gaining increased attention for dif- ferent reasons

Cremers, Daniel

116

Solar Cooling Using Variable Geometry Ejectors Centre for Sustainable Energy Systems  

E-Print Network (OSTI)

electrically driven heat pumps to be deployed to locations such as houses where a steady source of heat may pumps were other notable benefits. Heat pump cooling systems dominate the air-conditioning market to consider solar heat driven cooling systems, most prominently since the 1990s. The Ejector Heat Pump

117

Energy Efficient Single Stack Exhaust Fan Systems (E3S3F)  

E-Print Network (OSTI)

This paper first investigates the fan energy performance of a constant air volume exhaust system. Two single stack energy efficient exhaust fan systems (E3S3F) are presented. The E3S3F-I has the static pressure sensor located at the inlet...

Wang, G.; Liu, M.

2001-01-01T23:59:59.000Z

118

Real-time variable rate Pix® application system using a plant height sensor  

E-Print Network (OSTI)

The objective of this study was to develop a chemical application system that could measure plant size, determine the optimum chemical rate to apply and control that application. A plant height sensor, the MEPRT growth relationship software...

Beck, Andy Dwayne

2012-06-07T23:59:59.000Z

119

Variable-Speed Wind Generator System with Maximum Output Power Control  

Science Journals Connector (OSTI)

To achieve maximum output power from wind generator systems, the rotational speed of wind generators should be adjusted in real time according to natural wind speed. This chapter pays attention to an optimum rota...

Yoko Amano

2013-01-01T23:59:59.000Z

120

A Simple and Quick Chilled Water Loop Balancing for Variable Flow System  

E-Print Network (OSTI)

. It was built in 1995 with a modem EMCS control for the HVAC systems. The building was mostly occupied in late 1996. The whole complex primarily consists of outpatient clinic rooms, pharmacy, nuclear medicine, ICUs, CCUs, surgical areas, inpatient beds... the building owner, facility engineers or HVAC operators more opportunities to run the chilled water system more efficiently. Generally, the pump speeds are controlled by the EMCS or a stand-alone controller to maintain the differential pressure setpoints...

Zhu, Y.; Batten, T.; Turner, W. D.; Claridge, D. E.; Liu, M.

2000-01-01T23:59:59.000Z

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


121

Long-term electricity demand forecasting for power system planning using economic, demographic and climatic variables  

Science Journals Connector (OSTI)

The stochastic planning of power production overcomes the drawback of deterministic models by accounting for uncertainties in the parameters. Such planning accounts for demand uncertainties by using scenario sets and probability distributions. However, in previous literature, different scenarios were developed by either assigning arbitrary values or assuming certain percentages above or below a deterministic demand. Using forecasting techniques, reliable demand data can be obtained and inputted to the scenario set. This article focuses on the long-term forecasting of electricity demand using autoregressive, simple linear and multiple linear regression models. The resulting models using different forecasting techniques are compared through a number of statistical measures and the most accurate model was selected. Using Ontario's electricity demand as a case study, the annual energy, peak load and base load demand were forecasted up to the year 2025. In order to generate different scenarios, different ranges in the economic, demographic and climatic variables were used. [Received 16 October 2007; Revised 31 May 2008; Revised 25 October 2008; Accepted 1 November 2008

F. Chui; A. Elkamel; R. Surit; E. Croiset; P.L. Douglas

2009-01-01T23:59:59.000Z

122

Predicting the Effects of Short-Term Photovoltaic Variability on Power System Frequency for Systems with Integrated Energy Storage.  

E-Print Network (OSTI)

?? The percentage of electricity supplied by photovoltaic (PV) generators is steadily rising in power systems worldwide. This rise in PV penetration may lead to… (more)

Traube, Joshua White

2014-01-01T23:59:59.000Z

123

Development of a variable controlled inertia charging system for naturally aspirated diesel engines in heavy duty trucks  

Science Journals Connector (OSTI)

An idea for controlling the inertia charging effect of diesel engines have been developed. Although the conventional inertia charging system can provide an effect in a narrow driving range, the new concept covers the whole range of engine speeds and load conditions. The Hino EK100 naturally aspirated 13.3 dmł engine equipped with this variable controlled inertia charging system could meet the 1983 Japanese exhaust emission regulation (intensified to 470ppm of NOx on 6 Mode from the original value of 770ppm in 1974) while giving an improved fuel economy. This 199 kw engine is applied to the Hino heavy duty truck named the 'New Super Dolphin (Econo Diesel)'. One of the measures to offset the deterioration of engine performance caused by the reduction of exhaust gas emissions is to improve the combustion characteristics by increasing the excess air ratio. Although inertia charging can provide more excess air for the engine, this system has to have come fixed factors such as tuned pipe length and diameter etc. So the resonance zone is also fixed within a narrow engine speed range. And, moreover, out of such range, the air quantity has been reduced below that experienced without inertia charging. Thus variable control of the inertia charging with a mechanism to change the tuned pipe length is considered for this system. The intake air quantity is thus controlled to improve engine performance over a wide speed range at both full load and partial load. The engine can get a higher brake mean effective pressure of 0.90 MPa at peak torque and also improve fuel consumption even at partial load by reduced intake air quantity for minimizing gas exchange loss.

N. Eguchi; T. Kubodera; T. Otani; K. Usami

1986-01-01T23:59:59.000Z

124

Sensible and Latent Cooling Load Control Using Centrally-Ducted, Variable-Capacity Space Conditioning Systems in Low Sensible Load Environments  

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

Sensible and Latent Cooling Load Control Using Centrally-Ducted, Variable-Capacity Space Conditioning Systems in Low Sensible Load Environments James Cummings BA-PIRC; Florida Solar Energy Center Presented at BA Summer Meeting, July 26, 2012 The gist of my message * Fixed capacity AC systems generally provide good RH control in typical residences. * In low-load homes, they may be less effective in achieving good RH control. * On the other hand, variable capacity AC systems have several characteristics which can provide improved RH control in homes. - Both Nordyne and Carrier have variable capacity units, varying from about 40% to 100% of nominal full capacity. - What is variable capacity? -- condenser fan, compressor speed, and AHU fan speed. The gist, continued

125

Modelling repairable system reliability with explanatory variables and repair and maintenance actions  

Science Journals Connector (OSTI)

......However, in general, in RMs...overhaul of an engine (a midlife...used with diesel engines...g. from diesel engines, such as...is a quite general model, and...analysis of diesel engine failure data...systems with general repair......

Diederik Lugtigheid; agan Banjevic; Andrew K. S. Jardine

2004-04-01T23:59:59.000Z

126

Northwest Open Automated Demand Response Technology Demonstration Project  

E-Print Network (OSTI)

Air Volume VFD – Variable Frequency Drive XML – Extensiblepressure reset, variable frequency drive (VFD) position

Kiliccote, Sila

2010-01-01T23:59:59.000Z

127

The Effect of Pressure Difference Control on Hydraulic Stability in a Variable Flow Air Conditioning System  

E-Print Network (OSTI)

analysis is shown in table 3. Tab.3 Calculation results of direct return system terminal control j i 1 2 3 4 5 Yi 1 0 1 1 1 1 0 2 0.965 0 1 1 1 0.009 3 0.841 0.863 0 1 1 0.074 4 0.873 0.900 0.955 0 1 0.068 5 0.797 0.821 0.872 0.913 0 0.149 j... analysis is shown in table 3. Tab.3 Calculation results of direct return system terminal control j i 1 2 3 4 5 Yi 1 0 1 1 1 1 0 2 0.965 0 1 1 1 0.009 3 0.841 0.863 0 1 1 0.074 4 0.873 0.900 0.955 0 1 0.068 5 0.797 0.821 0.872 0.913 0 0.149 j...

Zhang, Z.; Fu, Y.; Chen, Y.

2006-01-01T23:59:59.000Z

128

Sub-Hour Solar Data for Power System Modeling From Static Spatial Variability Analysis: Preprint  

SciTech Connect

High penetration renewable integration studies need high quality solar power data with spatial-temporal correlations that are representative of a real system. This paper will summarize the research relating sequential point-source sub-hour global horizontal irradiance (GHI) values to static, spatially distributed GHI values. This research led to the development of an algorithm for generating coherent sub-hour datasets that span distances ranging from 10 km to 4,000 km. The algorithm, in brief, generates synthetic GHI values at an interval of one-minute, for a specific location, using SUNY/Clean Power Research, satellite-derived, hourly irradiance values for the nearest grid cell to that location and grid cells within 40 km.

Hummon, M.; Ibanez, E.; Brinkman, G.; Lew, D.

2012-12-01T23:59:59.000Z

129

Duct Leakage Impacts on VAV System Performance in Large Commercial  

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

Duct Leakage Impacts on VAV System Performance in Large Commercial Duct Leakage Impacts on VAV System Performance in Large Commercial Buildings Title Duct Leakage Impacts on VAV System Performance in Large Commercial Buildings Publication Type Report LBNL Report Number LBNL-53605 Year of Publication 2003 Authors Wray, Craig P., and Nance Matson Abstract The purpose of this study is to evaluate the variability of duct leakage impacts on air distribution system performance for typical large commercial buildings in California. Specifically, a hybrid DOE-2/TRNSYS sequential simulation approach was used to model the energy use of a low-pressure terminal-reheat variable-air-volume (VAV) HVAC system with six duct leakage configurations (tight to leaky) in nine prototypical large office buildings (representing three construction eras in three California climates where these types of buildings are common). Combined fan power for the variable-speed-controlled supply and return fans at design conditions was assumed to be 0.8 W/cfm. The VAV system that we simulated had perfectly insulated ducts, and maintained constant static pressure in the ducts upstream of the VAV boxes and a constant supply air temperature at the air-handler. Further evaluations of duct leakage impacts should be carried out in the future after methodologies are developed to deal with duct surface heat transfer effects, to deal with airflows entering VAV boxes from ceiling return plenums (e.g., to model parallel fan-powered VAV boxes), and to deal with static pressure reset and supply air temperature reset strategies.

130

Variable oxygen/nitrogen enriched intake air system for internal combustion engine applications  

DOE Patents (OSTI)

An air supply control system for selectively supplying ambient air, oxygen enriched air and nitrogen enriched air to an intake of an internal combustion engine includes an air mixing chamber that is in fluid communication with the air intake. At least a portion of the ambient air flowing to the mixing chamber is selectively diverted through a secondary path that includes a selectively permeable air separating membrane device due a differential pressure established across the air separating membrane. The permeable membrane device separates a portion of the nitrogen in the ambient air so that oxygen enriched air (permeate) and nitrogen enriched air (retentate) are produced. The oxygen enriched air and the nitrogen enriched air can be selectively supplied to the mixing chamber or expelled to atmosphere. Alternatively, a portion of the nitrogen enriched air can be supplied through another control valve to a monatomic-nitrogen plasma generator device so that atomic nitrogen produced from the nitrogen enriched air can be then injected into the exhaust of the engine. The oxygen enriched air or the nitrogen enriched air becomes mixed with the ambient air in the mixing chamber and then the mixed air is supplied to the intake of the engine. As a result, the air being supplied to the intake of the engine can be regulated with respect to the concentration of oxygen and/or nitrogen.

Poola, Ramesh B. (Woodridge, IL); Sekar, Ramanujam R. (Naperville, IL); Cole, Roger L. (Elmhurst, IL)

1997-01-01T23:59:59.000Z

131

A fuzzy logic supervisor for active and reactive power control of a variable speed wind energy conversion system associated to a flywheel storage system  

Science Journals Connector (OSTI)

In this paper, we propose a Wind Energy Conversion System (WECS) at variable speed using a Doubly Fed Induction Generator (DFIG) controlled on the rotor side through converters. A Flywheel Energy Storage System (FESS) is connected to the studied wind generator at the DC bus in order to evaluate its capacity to participate to the ancillary services. We study the improvement of the active and reactive power quality produced by the wind generator and its effect on the load voltage regulation connected to the wind generator. For that, a fuzzy logic supervisor is established to control the FESS operation and the DC bus voltage in order to smooth the active power fluctuations due to the random wind speed variations. A control law is also described to smooth the reactive power at the connection node to the grid.

Lilia Jerbi; Lotfi Krichen; Abderrazak Ouali

2009-01-01T23:59:59.000Z

132

Air-Side Energy Use Calculations for Four HVAC Systems: Dual Duct Constant Volume (DDCAV), Dual Duct Variable Volume (DDVAV), Constant Volume with Reheat (CAVRH), Variable Volume with Reheat (VAVRH), Four Pipe Fan Coil Unit (FC), Four Pipe Induction Unit (FI), and Single Zone (SZ) Systems, Revised June 2002  

E-Print Network (OSTI)

(CAVRH), and variable volume with reheat (VAVRH), four pipe fan coil unit (FC), four pipe induction unit (FI), and a single zone air conditioning system (SZ). These calculations are presented in spreadsheets that include a running commentary so...

Haberl, J. S.; Bou-Saada, T. E.; Saman, N. F.

2001-01-01T23:59:59.000Z

133

Variable Refrigerant Flow Systems  

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134

Abstract--Heart rate variability (HRV) is frequently used to measure autonomic nervous system (ANS) activity. However,  

E-Print Network (OSTI)

1 of 4 Abstract--Heart rate variability (HRV) is frequently used to measure autonomic nervous frequency (HF) ratio with little change in mean heart rate. Results suggest that nicotine affects both components may yield erroneous results. Keywords--Autonomic regulation, heart rate variability, Lomb

135

A computer simulation appraisal of non-residential low energy cooling systems in California  

SciTech Connect

An appraisal of the potential performance of different Low Energy Cooling (LEC) systems in nonresidential buildings in California is being conducted using computer simulation. The paper presents results from the first phase of the study, which addressed the systems that can be modeled, with the DOE-2.1E simulation program. The following LEC technologies were simulated as variants of a conventional variable-air-volume system with vapor compression cooling and mixing ventilation in the occupied spaces: Air-side indirect and indirect/direct evaporative pre-cooling. Cool beams. Displacement ventilation. Results are presented for four populous climates, represented by Oakland, Sacramento, Pasadena and San Diego. The greatest energy savings are obtained from a combination of displacement ventilation and air-side indirect/direct evaporative pre-cooling. Cool beam systems have the lowest peak demand but do not reduce energy consumption significantly because the reduction in fan energy is offse t by a reduction in air-side free cooling. Overall, the results indicate significant opportunities for LEC technologies to reduce energy consumption and demand in nonresidential new construction and retrofit.

Bourassa, Norman; Haves, Philip; Huang, Joe

2002-05-17T23:59:59.000Z

136

Wavelet based artificial neural network applied for energy efficiency enhancement of decoupled HVAC system  

Science Journals Connector (OSTI)

Control methodologies could lower energy demand and consumption of heating, ventilating and air conditioning (HVAC) systems and, simultaneously, achieve better comfort conditions. However, the application of classical controllers is unsatisfactory as HVAC systems are non-linear and the control variables such as temperature and relative humidity (RH) inside the thermal zone are coupled. The objective of this study is to develop and simulate a wavelet-based artificial neural network (WNN) for self tuning of a proportional-derivative (PD) controller for a decoupled bi-linear HVAC system with variable air volume and variable water flow responsible for controlling temperature and RH of a thermal zone, where thermal comfort and energy consumption of the system are evaluated. To achieve the objective, a WNN is used in series with an infinite impulse response (IIR) filter for faster and more accurate identification of system dynamics, as needed for on-line use and off-line batch mode training. The WNN-IIR algorithm is used for self-tuning of two PD controllers for temperature and RH. The simulation results show that the WNN-IIR controller performance is superior, as compared with classical PD controller. The enhancement in efficiency of the HVAC system is accomplished due to substantially lower consumption of energy during the transient operation, when the gain coefficients of PD controllers are tuned in an adaptive manner, as the steady state setpoints for temperature and RH are better reached in a shorter period of time. The multi-zone analyses are suggested for future work.

G. Jahedi; M.M. Ardehali

2012-01-01T23:59:59.000Z

137

Field demonstration of optimized variable speed compressor and condenser fan control for commercial refrigeration systems. Final report  

SciTech Connect

The demonstration project discussed in this report consisted of two separate programs intended to examine methods of implementing variable-frequency drives (VFDs) to increase the efficiency of supermarket refrigeration racks. The first program examined the optimum control strategy for minimizing the power consumption of medium-temperature parallel compressor racks driven by VFDs. The second program, aimed at developing the optimum control strategy for variable-speed control of supermarket condenser fans.

NONE

1997-11-01T23:59:59.000Z

138

Modelica-based Modeling and Simulation to Support Research and Development in Building Energy and Control Systems  

SciTech Connect

Traditional building simulation programs possess attributes that make them difficult to use for the design and analysis of building energy and control systems and for the support of model-based research and development of systems that may not already be implemented in these programs. This article presents characteristic features of such applications, and it shows how equation-based object-oriented modelling can meet requirements that arise in such applications. Next, the implementation of an open-source component model library for building energy systems is presented. The library has been developed using the equation-based object-oriented Modelica modelling language. Technical challenges of modelling and simulating such systems are discussed. Research needs are presented to make this technology accessible to user groups that have more stringent requirements with respect to the numerical robustness of simulation than a research community may have. Two examples are presented in which models from the here described library were used. The first example describes the design of a controller for a nonlinear model of a heating coil using model reduction and frequency domain analysis. The second example describes the tuning of control parameters for a static pressure reset controller of a variable air volume flow system. The tuning has been done by solving a non-convex optimization problem that minimizes fan energy subject to state constraints.

Wetter, Michael

2009-02-12T23:59:59.000Z

139

Commissioning of A Large Office Building in Texas - A Case Study  

E-Print Network (OSTI)

Control System) programming and operation, and the installation of automatic chiller isolation valves, in addition to calibration and repair of building VAV (Variable Air Volume) boxes. In the case study building, four air-cooled chillers and two chilled...

Deng, S.; Turner, W. D.; Liu, M.

2000-01-01T23:59:59.000Z

140

Innovative, Cost Effective and Energy Efficient Desgin for New Construction at a Texas High School  

E-Print Network (OSTI)

, which includes innovative dual-duct Variable Air Volume (VAV) systems for cooling and pre-treated ventilation air delivery integrated with occupancy sensors and digital controls, and optimized HVAC controls for dynamic balancing of air and hydronic sides...

Khan, S.; Bible, M.

2013-01-01T23:59:59.000Z

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


141

Case Study: The Effective Use of an Extensive Logical rule Based Data Analytics Approach in Establishing Root Cause of Performance Issues in Widespread Deployments of Unitary Space Air Conditioning Units  

E-Print Network (OSTI)

Today a significant percentage of office spaces are air conditioned using widely deployed unitary systems, either Fan Coil Units (FCU) or Variable Air Volume (VAV) boxes, to achieve high degrees of air conditioned zonal control. However establishing...

Brady, N.

2013-01-01T23:59:59.000Z

142

Variable susceptance excitation control for dynamic performance improvement of a stand-alone wind turbine induction generator system  

Science Journals Connector (OSTI)

Isolated wind farms employ simple squirrel cage induction generators driven by variable speed wind turbines. Lacking control capability, such generation can contribute very little to network support. Wind turbines mostly do not take part in voltage and frequency control and if a disturbance occurs, the turbines may be disconnected and reconnected when normal operation has been resumed. From operation viewpoint, this is definitely not acceptable. A primary reason for the rigidity of operation is the lack of excitation adaptation under variable wind conditions. This article proposes incorporation of a variable capacitance controller at the generator terminal which will automatically adjust the needed excitation. Further improvement of transient profile of the stand-alone wind turbine generator has been proposed through inclusion of additional stabilising control. Simulation studies show that the proposed excitation controller with additional PID circuit provides very good transient profile following reasonable input torque variations.

A.H.M.A. Rahim; M. Ahsanul Alam

2009-01-01T23:59:59.000Z

143

Optimal Operation of Variable Speed Pumping System in China’s Eastern Route Project of S?to?N Water Diversion Project  

Science Journals Connector (OSTI)

A dynamic planning model for optimizing operation of variable speed pumping system aiming at minimum power consumption was proposed to achieve economic operation. The No. 4 Jiangdu Pumping Station a source pumping station in China’s Eastern Route of South?to?North Water Diversion Project is taken as a study case. Since the sump water level of Jiangdu Pumping Station is affected by the tide of Yangtze River the daily?average heads of the pumping system varies yearly from 3.8m to 7.8m and the tide level difference in one day up to 1.2m. Comparisons of operation electricity cost between optimized variable speed and fixed speed operations of pumping system were made. When the full load operation mode is adopted whether or not electricity prices in peak?valley periods are considered the benefits of variable speed operation cannot compensate the energy consumption of the VFD. And when the pumping system operates in part load and the peak?valley electricity prices are considered the pumping system should cease operation or lower its rotational speed in peak load hours since the electricity price are much higher and to the contrary the pumping system should raise its rotational speed in valley load hours to pump more water. The computed results show that if the pumping system operates in 80% or 60% loads the energy consumption cost of specified volume of water will save 14.01% and 26.69% averagely by means of optimal variable speed operation and the investment on VFD will be paid back in 2 or 3 years. However if the pumping system operates in 80% or 60% loads and the energy cost is calculated in non peak?valley electricity price the repayment will be lengthened up to 18 years. In China’s S?to?N Water Diversion Project when the market operation and peak?valley electricity prices are taken into effect to supply water and regulate water levels in regulation reservoirs as Hongzehu Lake Luomahu Lake etc. the economic operation of water?diversion pumping stations will be vital and the adoption of VFDs to achieve optimal operation may be a good choice.

Jilin Cheng; Lihua Zhang; Rentian Zhang; Yi Gong; Honggeng Zhu; Dongsheng Deng; Xuesong Feng; Jinxian Qiu

2010-01-01T23:59:59.000Z

144

Effects of variable renewable power on a country-scale electricity system: High penetration of hydro power plants and wind farms in electricity generation  

Science Journals Connector (OSTI)

The present article analyses the effects caused by variable power. The analysis concerns a country-scale electricity system with a relatively high penetration of seasonally variable hydro power plants and wind farms in the total electricity generation in 2030. For this purpose, the Latvian electricity system was chosen as an appropriate case study, as around half of its electricity is already generated from hydro power and numerous wind farm installations are planned for 2030. Results indicate that in such systems high renewable power variations occur between seasons causing a high probability of power deficit in the winter and power surplus in the spring. Based on the results, the wind farms' influence on the power deficit and surplus occurrences are discussed in detail. Wind farm generation decreases the probability of the electricity system being in power deficit, but increases the probability of the system being in power surplus. In the latter situation, the maximum value of power surplus increases since it is enhanced by the wind farm generation. Probability equations to express these changes are provided.

Arturs Purvins; Ioulia T. Papaioannou; Irina Oleinikova; Evangelos Tzimas

2012-01-01T23:59:59.000Z

145

Demand Response Opportunities and Enabling Technologies for Data Centers: Findings From Field Studies  

E-Print Network (OSTI)

units, and variable frequency drives (VFD). When globalVariable Air Volume Variable Frequency Drive Western Area

Ghatikar, Girish

2014-01-01T23:59:59.000Z

146

Demand Shifting with Thermal Mass in Large Commercial Buildings in a California Hot Climate Zone  

E-Print Network (OSTI)

are equipped with variable frequency drives (VFD). There areVariable air volume Variable frequency drive Whole Building

Xu, Peng

2010-01-01T23:59:59.000Z

147

Theoretical model for evaluation of variable frequency drive for cooling water pumps in sea water based once through condenser cooling water systems  

Science Journals Connector (OSTI)

In sea water based once through cooling water system for power plants, sea water is pumped through the condenser and the return hot water is let back to sea. The cooling water pumps (CWP) in power plants generally operate at constant speed, pumping variable quantities of water depending on the tide level in the sea. The variable flow causes variation in condenser back pressure resulting in changes in the turbine cycle heat rate. If the pump speed is controlled using a variable frequency drive (VFD) to maintain design flow irrespective of the tide level, the CWP power consumption can be reduced compared to the case with constant speed CWP. However, the turbine cycle heat rate benefit that could have accrued at tide levels above the pre defined level (for fixing the CWP head) with constant speed CWP would have to be sacrificed. This paper provides a theoretical model with a typical case study to establish viability of providing VFD for \\{CWPs\\} in power plants with sea water based once through condenser cooling water system.

R. Harish; E.E. Subhramanyan; R. Madhavan; S. Vidyanand

2010-01-01T23:59:59.000Z

148

Dynamic Analysis of Hybrid Energy Systems under Flexible Operation and Variable Renewable Generation -- Part I: Dynamic Performance Analysis and Part II: Dynamic Cost  

SciTech Connect

Dynamic analysis of hybrid energy systems (HES) under flexible operation and variable renewable generation is considered in order to better understand various challenges and opportunities associated with the high system variability arising from the integration of renewable energy into the power grid. Unique consequences are addressed by devising advanced HES solutions in which multiple forms of energy commodities, such as electricity and chemical products, may be exchanged. Dynamic models of various unit operations are developed and integrated within two different HES options. One HES option, termed traditional, produces electricity only and consists of a primary heat generator (PHG) (e.g., a small modular reactor), a steam turbine generator, a wind farm, and a battery storage. The other HES option, termed advanced, includes not only the components present in the traditional option but also a chemical plant complex to repurpose excess energy for non-electricity services, such as for the production of chemical goods (e.g., transportation fuel). In either case, a given HES is connected to the power grid at a point of common coupling and requested to deliver a certain electricity generation profile as dictated by a regional power grid operator based on a predicted demand curve. Dynamic analysis of these highly-coupled HES are performed to identify their key dynamical properties and limitations and to prescribe solutions for best managing and mitigating the high variability introduced from incorporating renewable energy into the energy mix. A comparative dynamic cost analysis is also conducted to determine best HES options. The cost function includes a set of metrics for computing fixed costs, such as fixed operations and maintenance (O&M) and overnight capital costs, and also variable operational costs, such as cost of variability, variable O&M cost, and cost of environmental impact, together with revenues. Assuming different options for implementing PHG (e.g., natural gas, coal, nuclear), preliminary results identify the level of renewable penetration at which a given advanced HES option (e.g., a nuclear hybrid) becomes increasingly more economical than a traditional electricity-only generation solution. Conditions are also revealed under which carbon resources may be better utilized as carbon sources for chemical production rather than as combustion material for electricity generation.

Humberto E. Garcia; Amit Mohanty; Wen-Chiao Lin; Robert S. Cherry

2013-04-01T23:59:59.000Z

149

Evaluation of autonomic nervous system by salivary alpha-amylase level and heart rate variability in patients with schizophrenia  

Science Journals Connector (OSTI)

Several researches indicate that autonomic nervous system (ANS) dysfunction in patients with schizophrenia. Recently, salivary alpha-amylase (sAA) has been employed as a...

Masa Ieda; Tsuyoshi Miyaoka; Rei Wake…

2014-02-01T23:59:59.000Z

150

Research on Variable Parameter Set in Complex Multi-Domain Physical System and Its Repeatedly Simulating Arithmetic  

Science Journals Connector (OSTI)

As a unified modeling simulation language for complex multi-domain physical system, now Modelica is getting more and more attention, and...

Renwang Li; YiZhong Wu; Liang Gao…

2009-01-01T23:59:59.000Z

151

Assessment of Risk in a Production System with the Use of the FMEA Analysis and Linguistic Variables  

Science Journals Connector (OSTI)

The paper describes a method for analysing and assessing the risk in production systems. A process of ore transportation process with the use of a belt conveyor was used as an example. Ishikawa diagram was used t...

Anna Burduk

2012-01-01T23:59:59.000Z

152

Variability in natural gas fuel composition and its effects on the performance of catalytic combustion systems. Final report for period September 18, 1998 - September 17, 2000  

SciTech Connect

Natural gas is composed primarily of methane with small amounts of higher hydrocarbons and diluents, which vary by region and over time. Compositions of natural gas from domestic and worldwide sources were surveyed with respect to content of higher hydrocarbons and diluents. The survey showed slight compositional variability between most of the gases, with a small fraction of them containing significantly larger contents of higher hydrocarbons than the mean. As gas-fired turbines will be used for power generation all over the world, they will need to tolerate operation with fuels with a wide variety of compositions, particularly with respect to the concentration of higher hydrocarbons and diluents. Subscale catalytic combustion modules typical of those used in gas turbine power generation with ultra low emissions of pollutants were tested in a subscale test system with natural gas alone and with added known levels of hydrocarbon compounds and diluents. The range of compositions tested contained the range observed in the survey. Test results were used to calculate the effect of composition on catalyst performance. The compositional variability is of little consequence to the catalyst for most of the gases in the survey, including nearly all of the gases delivered in the U.S. To accommodate the remaining gases, the catalyst inlet temperature must be lowered to maintain combustor durability. These results support commercial acceptance of catalytic combustion systems for use in natural gas fired turbines in distributed power generation with ultra low NO{sub x} emissions.

Ginter, David; Simchick, Chuck; Schlatter, Jim

2002-03-01T23:59:59.000Z

153

Integrability aspects with optical solitons of a generalized variable-coefficient N-coupled higher order nonlinear Schroedinger system from inhomogeneous optical fibers  

SciTech Connect

For describing the long-distance communication and manufacturing problems of N fields propagation in inhomogeneous optical fibers, we consider a generalized variable-coefficient N-coupled nonlinear Schroedinger system with higher order effects such as the third-order dispersion, self-steepening and self-frequency shift. Using the Painleve singularity structure analysis, we obtain two cases for this system to admit the Painleve property. Then for case (1) we derive the optical dark solitons via solving the Hirota bilinear equations; and based on the obtained (2N+1)x(2N+1) Lax pair, we construct the Darboux transformation to obtain the optical bright solitons (including the multisoliton profiles) for case (2). Finally, the features of optical solitons (both dark and bright ones) in inhomogeneous optical fibers are analyzed and graphically discussed.

Lue Xing; Li Juan; Zhang Haiqiang; Xu Tao; Li Lili [School of Science, Beijing University of Posts and Telecommunications, P.O. Box 49, Beijing 100876 (China); Tian Bo [School of Science, Beijing University of Posts and Telecommunications, P.O. Box 49, Beijing 100876 (China); State Key Laboratory of Software Development Environment, Beijing University of Aeronautics and Astronautics, Beijing 100191 (China); Key Laboratory of Information Photonics and Optical Communications (BUPT), Ministry of Education, Beijing University of Posts and Telecommunications, P.O. Box 128, Beijing 100876 (China)

2010-04-15T23:59:59.000Z

154

Simulation study on lignite-fired power system integrated with flue gas drying and waste heat recovery – Performances under variable power loads coupled with off-design parameters  

Science Journals Connector (OSTI)

Abstract Lignite is a kind of low rank coal with high moisture content and low net heating value, which is mainly used for electric power generation. However, the thermal efficiency of power plants firing lignite directly is very low. Pre-drying is a proactive option, dehydrating raw lignite to raise its heating value, to improve the power plant thermal efficiency. A pre-dried lignite-fired power system integrated with boiler flue gas drying and waste heat recovery was proposed in this paper. The plant thermal efficiency could be improved by 1.51% at benchmark condition due to pre-drying and waste heat recovery. The main system performances under variable power loads were simulated and analyzed. Simulation results show that the improvement of plant thermal efficiency reduced to 1.36% at 50% full load. Moreover, the influences of drying system off-design parameters were simulated coupled with power loads. The variation tendencies of main system parameters were obtained. The influence of pre-drying degree (including moisture content of pre-dried lignite and raw lignite) on the plant thermal efficiency diminishes gradually with the decreasing power load. The dryer thermal efficiency and dryer exhaust temperature are also main factors and the influences on system parameters have been quantitatively analyzed.

Xiaoqu Han; Ming Liu; Jinshi Wang; Junjie Yan; Jiping Liu; Feng Xiao

2014-01-01T23:59:59.000Z

155

Plug-in hybrid electric vehicles as a way to maximize the integration of variable renewable energy in power systems: The case of wind generation in northeastern Brazil  

Science Journals Connector (OSTI)

Several studies have proposed different tools for analyzing the integration of variable renewable energy into power grids. This study applies an optimization tool to model the expansion of the electric power system in northeastern Brazil, enabling the most efficient dispatch of the variable output of the wind farms that will be built in the region over the next 20 years. The expected combined expansion of wind generation with conventional inflexible generation facilities, such as nuclear plants and run-of-the-river hydropower plants, poses risks of future mismatch between supply and demand in northeastern Brazil. Therefore, this article evaluates the possibility of using a fleet of plug-in hybrid electric vehicles (PHEVs) to regularize possible energy imbalances. Findings indicate that a dedicated fleet of 500 thousand \\{PHEVs\\} in 2015, and a further 1.5 million in 2030, could be recharged overnight to take advantage of the surplus power generated by wind farms. To avoid the initial costs of smart grids, this article suggests, as a first step, the use of a governmental PHEV fleet that allows fleet managers to control battery charging times. Finally, the study demonstrates the advantages of optimizing simultaneously the power and transport sectors to test the strategy suggested here.

Bruno Soares M.C. Borba; Alexandre Szklo; Roberto Schaeffer

2012-01-01T23:59:59.000Z

156

Variable Definitions  

Gasoline and Diesel Fuel Update (EIA)

Data System CSV File Documentation Data System CSV File Documentation Energy Source Tables This document explains the contents of the comma-separated value (CSV) files by energy source located on the State Energy Data System (SEDS) web page at http://www.eia.gov/state/seds/seds-data-fuel.cfm. There is a CSV file for the most recent year's data for each energy source as shown in the HTML and PDF data tables. In some cases there is one data file for two tables. The first record in each file contains the column headings. The first data field is the state code (2 characters), followed by the data identifier (5-character mnemonic code, or MSN), and then the estimates for the latest year. Detailed descriptions of the state codes, data identifiers, and units are listed in the latter part of this documentation.

157

VARIABLE AND EXTREME IRRADIATION CONDITIONS IN THE EARLY SOLAR SYSTEM INFERRED FROM THE INITIAL ABUNDANCE OF {sup 10}Be IN ISHEYEVO CAIs  

SciTech Connect

A search for short-lived {sup 10}Be in 21 calcium-aluminum-rich inclusions (CAIs) from Isheyevo, a rare CB/CH chondrite, showed that only 5 CAIs had {sup 10}B/{sup 11}B ratios higher than chondritic correlating with the elemental ratio {sup 9}Be/{sup 11}B, suggestive of in situ decay of this key short-lived radionuclide. The initial ({sup 10}Be/{sup 9}Be){sub 0} ratios vary between {approx}10{sup -3} and {approx}10{sup -2} for CAI 411. The initial ratio of CAI 411 is one order of magnitude higher than the highest ratio found in CV3 CAIs, suggesting that the more likely origin of CAI 411 {sup 10}Be is early solar system irradiation. The low ({sup 26}Al/{sup 27}Al){sub 0} [{<=} 8.9 Multiplication-Sign 10{sup -7}] with which CAI 411 formed indicates that it was exposed to gradual flares with a proton fluence of a few 10{sup 19} protons cm{sup -2}, during the earliest phases of the solar system, possibly the infrared class 0. The irradiation conditions for other CAIs are less well constrained, with calculated fluences ranging between a few 10{sup 19} and 10{sup 20} protons cm{sup -2}. The variable and extreme value of the initial {sup 10}Be/{sup 9}Be ratios in carbonaceous chondrite CAIs is the reflection of the variable and extreme magnetic activity in young stars observed in the X-ray domain.

Gounelle, Matthieu [Laboratoire de Mineralogie et de Cosmochimie du Museum, CNRS and Museum National d'Histoire Naturelle, UMR 7202, CP52, 57 rue Cuvier, F-75005 Paris (France); Chaussidon, Marc; Rollion-Bard, Claire, E-mail: gounelle@mnhn.fr [Centre de Recherches Petrographiques et Geochimiques, CRPG-CNRS, BP 20, F-54501 Vandoeuvre-les-Nancy Cedex (France)

2013-02-01T23:59:59.000Z

158

Strategy Guideline: Compact Air Distribution Systems  

SciTech Connect

This Strategy Guideline discusses the benefits and challenges of using a compact air distribution system to handle the reduced loads and reduced air volume needed to condition the space within an energy efficient home. Traditional systems sized by 'rule of thumb' (i.e., 1 ton of cooling per 400 ft2 of floor space) that 'wash' the exterior walls with conditioned air from floor registers cannot provide appropriate air mixing and moisture removal in low-load homes. A compact air distribution system locates the HVAC equipment centrally with shorter ducts run to interior walls, and ceiling supply outlets throw the air toward the exterior walls along the ceiling plane; alternatively, high sidewall supply outlets throw the air toward the exterior walls. Potential drawbacks include resistance from installing contractors or code officials who are unfamiliar with compact air distribution systems, as well as a lack of availability of low-cost high sidewall or ceiling supply outlets to meet the low air volumes with good throw characteristics. The decision criteria for a compact air distribution system must be determined early in the whole-house design process, considering both supply and return air design. However, careful installation of a compact air distribution system can result in lower material costs from smaller equipment, shorter duct runs, and fewer outlets; increased installation efficiencies, including ease of fitting the system into conditioned space; lower loads on a better balanced HVAC system, and overall improved energy efficiency of the home.

Burdick, A.

2013-06-01T23:59:59.000Z

159

Duct leakage impacts on VAV system performance in California large commercial buildings  

SciTech Connect

The purpose of this study is to evaluate the variability of duct leakage impacts on air distribution system performance for typical large commercial buildings in California. Specifically, a hybrid DOE-2/TRNSYS sequential simulation approach was used to model the energy use of a low-pressure terminal-reheat variable-air-volume (VAV) HVAC system with six duct leakage configurations (tight to leaky) in nine prototypical large office buildings (representing three construction eras in three California climates where these types of buildings are common). Combined fan power for the variable-speed-controlled supply and return fans at design conditions was assumed to be 0.8 W/cfm. Based on our analyses of the 54 simulation cases, the increase in annual fan energy is estimated to be 40 to 50% for a system with a total leakage of 19% at design conditions compared to a tight system with 5% leakage. Annual cooling plant energy also increases by about 7 to 10%, but reheat energy decreases (about 3 to 10%). In combination, the increase in total annual HVAC site energy is 2 to 14%. The total HVAC site energy use includes supply and return fan electricity consumption, chiller and cooling tower electricity consumption, boiler electricity consumption, and boiler natural gas consumption. Using year 2000 average commercial sector energy prices for California ($0.0986/kWh and $7.71/Million Btu), the energy increases result in 9 to 18% ($7,400 to $9,500) increases in HVAC system annual operating costs. Normalized by duct surface area, the increases in annual operating costs are 0.14 to 0.18 $/ft{sup 2}. Using a suggested one-time duct sealing cost of $0.20 per square foot of duct surface area, these results indicate that sealing leaky ducts in VAV systems has a simple payback period of about 1.3 years. Even with total leakage rates as low as 10%, duct sealing is still cost effective. This suggests that duct sealing should be considered at least for VAV systems with 10% or more total duct leakage. The VAV system that we simulated had perfectly insulated ducts, and maintained constant static pressure in the ducts upstream of the VAV boxes and a constant supply air temperature at the airhandler. Further evaluations of duct leakage impacts should be carried out in the future after methodologies are developed to deal with duct surface heat transfer effects, to deal with airflows entering VAV boxes from ceiling return plenums (e.g., to model parallel fan-powered VAV boxes), and to deal with static pressure reset and supply air temperature reset strategies.

Wray, Craig P.; Matson, Nance E.

2003-10-01T23:59:59.000Z

160

Renewable variable speed hybrid system   

E-Print Network (OSTI)

At present many remote and Island communities rely solely on diesel powered generators to provide electricity. Diesel fuel is both expensive and polluting and the constant speed operation of the diesel engine is inefficient. ...

Stott, Paul Anthony

2010-01-01T23:59:59.000Z

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


161

Operating Reserves and Variable Generation  

SciTech Connect

This report tries to first generalize the requirements of the power system as it relates to the needs of operating reserves. It also includes a survey of operating reserves and how they are managed internationally in system operations today and then how new studies and research are proposing they may be managed in the future with higher penetrations of variable generation.

Ela, E.; Milligan, M.; Kirby, B.

2011-08-01T23:59:59.000Z

162

A theoretical study of a special detonation regime of operation of a pulse detonation device with a variable cross section detonation combustion chamber and a valveless supply system  

Science Journals Connector (OSTI)

The results of a theoretical study of the special detonation regime that arises in a pulse detonation device with a variable cross section combustion ... location of the diaphragm. Since the pulse detonation devi...

L. G. Gvozdeva; D. I. Baklanov; I. N. Ryzhkina…

2009-06-01T23:59:59.000Z

163

Atmospheric Carbon Dioxide Variability in the Community Earth System Model: Evaluation and Transient Dynamics during the Twentieth and Twenty-First Centuries  

Science Journals Connector (OSTI)

Changes in atmospheric CO2 variability during the twenty-first century may provide insight about ecosystem responses to climate change and have implications for the design of carbon monitoring programs. This paper describes changes in the three-...

Gretchen Keppel-Aleks; James T. Randerson; Keith Lindsay; Britton B. Stephens; J. Keith Moore; Scott C. Doney; Peter E. Thornton; Natalie M. Mahowald; Forrest M. Hoffman; Colm Sweeney; Pieter P. Tans; Paul O. Wennberg; Steven C. Wofsy

2013-07-01T23:59:59.000Z

164

The Community Earth System Model (CESM) Large Ensemble Project: A Community Resource for Studying Climate Change in the Presence of Internal Climate Variability  

Science Journals Connector (OSTI)

While internal climate variability is known to affect climate projections, its influence is often underappreciated and confused with model error. Why? In general, modeling centers contribute a small number of realizations to international climate ...

J. E. Kay; C. Deser; A. Phillips; A. Mai; C. Hannay; G. Strand; J. M. Arblaster; S. C. Bates; G. Danabasoglu; J. Edwards; M. Holland; P. Kushner; J.-F. Lamarque; D. Lawrence; K. Lindsay; A. Middleton; E. Munoz; R. Neale; K. Oleson; L. Polvani; M. Vertenstein

165

Energy performance of air distribution systems part II: room air stratification full scale testing  

E-Print Network (OSTI)

and are connected to a fan coil unit by flexible ductwork asvariable air volume fan coil units typically used in

Webster, Tom; Lukaschek, Wolfgang; Dickeroff, Darryl; Bauman, Fred

2007-01-01T23:59:59.000Z

166

Atmospheric Carbon Dioxide Variability in the Community Earth System Model: Evaluation and Transient Dynamics during the Twentieth and Twenty-First Centuries  

E-Print Network (OSTI)

in the Community Earth System Model: Evaluation andpredictions from CMIP5 Earth system models and comparisonusing the Community Earth System Model–Biogeochemistry (

2013-01-01T23:59:59.000Z

167

Variable Temperature Scanning Probe Microscope | EMSL  

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

EMSL's ultra-high vacuum, variable-temperature scanning probe microscope system, or UHV VT SPM, is a state-of-the-art surface science tool comprising multiple complementary...

168

The! Community! Earth! System! Model! (CESM)! Large! Ensemble! Project:! A! Community!3! Resource!for!Studying!Climate!Change!in!the!Presence!of!Internal!Climate!Variability!4!  

E-Print Network (OSTI)

!1! !2! The! Community! Earth! System! Model! (CESM)! Large! Ensemble! Project:! A! Community!3!Earth!System!Model!(CESM)!community!designed!the!CESM!Large!Ensemble!39! (CESMWLE)!with!the!explicit

Kay, Jennifer

169

Variable trim compressor – a new approach to variable compressor geometry  

Science Journals Connector (OSTI)

ABSTRACT Variable compressor geometry can be employed irrespective of the combustion process selected. It provides the capability of improving response behavior, reducing fuel consumption or cutting exhaust emissions from exhaust-gas turbocharged engines. Previous concepts on variable compressor geometries have been based on using inlet guide vanes to impart a swirl motion to the air that is fed to the compressor with the ultimate aim of enhancing the angle at which the flow of air enters the blade channel. This paper shows an inlet guide configuration that is based on a different operating principle. The inlet guide assembly shown here is designed in a way that minimizes any pressure losses even at high flow rates. Numerical studies were carried out using CFD to test the system's sensitivity. Based on these studies, a rigid conical element was then produced and the potential for increasing efficiency (up to 7% points) and shifting the surge line (up to 33%) verified on a turbocharger test bench. Finally, a design configuration is presented for a variable system.

P. Grigoriadis; S. Müller; A. Benz; M. Sens

2012-01-01T23:59:59.000Z

170

Investigations into the effects of environmental and physical variables on the growth of natural and transplanted populations of Ruppia maritima L. s.l. in the Galveston Bay System, Texas  

E-Print Network (OSTI)

was there at the end. ACKNOWLEGMENTS I would like to thank the staff at the Brazoria National Wildlife Refuge (Ron Brisbee and Mike Lange) for allowing me access the National Wildlife Refuge sites. I would also like to thank Dr. Jim Webb's undergraduate students... INTO THE EFFECTS OF VARIOUS ENVIRONMENTAL AND PHYSICAL VARIABLES ON THE GROWTH OF NATURAL POPULATIONS OF RtJPPIA MARITIMA L. S. L. IN THE GALVESTON BAY SYSTEM 5 Introduction . . . 5 Site Descriptions 6 Materials and Methods . 15 Sampling Station...

Schubert, William James

2012-06-07T23:59:59.000Z

171

Chapter Seven - Variable speed drives  

Science Journals Connector (OSTI)

Publisher Summary The electromechanical controllers are a kind of variable speed drives (VSDs) that are obsolete but are still in use because when a motor and a drive is combined, they become a power drive system (PDS). There are two ways of varying the speed of an induction motor, either by varying the motor slip or by varying the supply frequency. The preferred practice for electrical speed variation is to change the supply frequency with a variable frequency drive (VFD). Many other designs also have been developed. However, except the specialized applications, few are still in operation. A number of motor and drive manufacturers are now producing the integrated motor/VFD units. These units consist of a motor and a specially designed VFD, produced as a single package, with the VFD unit mounted variously on the top, side, or end of the motor.

Europump; Hydraulic Institute

2005-01-01T23:59:59.000Z

172

STATE OF CALIFORNIA FAN POWER CONSUMPTION  

E-Print Network (OSTI)

STATE OF CALIFORNIA FAN POWER CONSUMPTION CEC-MECH-4C (Revised 08/09) CALIFORNIA ENERGY COMMISSION FAN POWER CONSUMPTION MECH-4C PROJECT NAME: DATE: NOTE: Provide one copy of this worksheet for each Systems or Variable Air Volume (VAV) Systems when using the Prescriptive Approach. See Power Consumption

173

Energy conservation measures in an institutional building by dynamic simulation using designbuilder  

Science Journals Connector (OSTI)

In this study, various energy conservation measures (ECMs) on heating, ventilating and air conditioning (HVAC) and lighting systems for a 4-storied building in subtropical (hot and humid climate) Central Queensland, Australia are evaluated using the ... Keywords: designbuilder, energy conservation measures, energy efficient lighting and day light control, energy simulation, hot-humid climate, variable air volume system

M. M. Rahman; M. G. Rasul; M. M. K. Khan

2008-02-01T23:59:59.000Z

174

Variable Frequency Drives  

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

How BPA Supports VFDs Rebates are available from your utility for Variable Frequency Drives on pumps 20hp or greater and storage fans.. Energy savings from VFDs vary and can...

175

Advanced Variable Speed Air-Source Integrated Heat Pump | Department...  

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

Integrated Heat Pump prototype system and field test site near Knoxville, TN Credit: Oak Ridge National Lab Advanced variable-speed Air Source Integrated Heat Pump prototype...

176

Variable Frequency Pump Drives  

E-Print Network (OSTI)

-frequency electric motor drive. What is happenin9 with variable frequency driven pun,ps is a classical illustration that evolution in technical products takes place not only because of changes in the processes served by these products, or because of innovations...-pole 3550 rpm squirrel caqe induction motor became available in the early 1930s that high pressure pumps operating at that speed could be buil t. And now, in the 1980s, the development of the solid-state, variable frequency electric motor drive...

Karassik, I. J.; Petraccaro, L. L.; McGuire, J. T.

177

--No Title--  

Annual Energy Outlook 2012 (EIA)

Variable Air-Volume System ... 2,369 47.2 29.2 19.7 37.9 83.8 17.5 0.35 7.37 Economizer Cycle ... 2,242 46.9 30.4 18.9 41.8 85.7 16.4 0.34 7.30 HVAC...

178

Integrating Variable Renewable Energy: Challenges and Solutions  

SciTech Connect

In the U.S., a number of utilities are adopting higher penetrations of renewables, driven in part by state policies. While power systems have been designed to handle the variable nature of loads, the additional supply-side variability and uncertainty can pose new challenges for utilities and system operators. However, a variety of operational and technical solutions exist to help integrate higher penetrations of wind and solar generation. This paper explores renewable energy integration challenges and mitigation strategies that have been implemented in the U.S. and internationally, including forecasting, demand response, flexible generation, larger balancing areas or balancing area cooperation, and operational practices such as fast scheduling and dispatch.

Bird, L.; Milligan, M.; Lew, D.

2013-09-01T23:59:59.000Z

179

Momentum Map and Action-Angle Variables for Nambu Dynamics  

E-Print Network (OSTI)

Momentum map is a reduction procedure that reduces the dimension of a Hamiltonian system to the lower ones. It is shown that behavior of the action-angle variables under the momentum map generates the new action-angle variables for the reduced system considered as a Nambu structure. The symmetrical top is given as an illustration.

A. Tegmen

2005-08-29T23:59:59.000Z

180

Variable depth core sampler  

DOE Patents (OSTI)

A variable depth core sampler apparatus comprising a first circular hole saw member, having longitudinal sections that collapses to form a point and capture a sample, and a second circular hole saw member residing inside said first hole saw member to support the longitudinal sections of said first hole saw member and prevent them from collapsing to form a point. The second hole saw member may be raised and lowered inside said first hole saw member.

Bourgeois, Peter M. (Hamburg, NY); Reger, Robert J. (Grand Island, NY)

1996-01-01T23:59:59.000Z

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


181

Variable laser attenuator  

DOE Patents (OSTI)

The disclosure relates to low loss, high power variable attenuators comprising one or more transmissive and/or reflective multilayer dielectric filters. The attenuator is particularly suitable to use with unpolarized lasers such as excimer lasers. Beam attenuation is a function of beam polarization and the angle of incidence between the beam and the filter and is controlled by adjusting the angle of incidence the beam makes to the filter or filters. Filters are selected in accordance with beam wavelength. 9 figs.

Foltyn, S.R.

1987-05-29T23:59:59.000Z

182

Variable depth core sampler  

DOE Patents (OSTI)

A variable depth core sampler apparatus is described comprising a first circular hole saw member, having longitudinal sections that collapses to form a point and capture a sample, and a second circular hole saw member residing inside said first hole saw member to support the longitudinal sections of said first hole saw member and prevent them from collapsing to form a point. The second hole saw member may be raised and lowered inside said first hole saw member. 7 figs.

Bourgeois, P.M.; Reger, R.J.

1996-02-20T23:59:59.000Z

183

Measuring spatial variability in soil characteristics  

DOE Patents (OSTI)

The present invention provides systems and methods for measuring a load force associated with pulling a farm implement through soil that is used to generate a spatially variable map that represents the spatial variability of the physical characteristics of the soil. An instrumented hitch pin configured to measure a load force is provided that measures the load force generated by a farm implement when the farm implement is connected with a tractor and pulled through or across soil. Each time a load force is measured, a global positioning system identifies the location of the measurement. This data is stored and analyzed to generate a spatially variable map of the soil. This map is representative of the physical characteristics of the soil, which are inferred from the magnitude of the load force.

Hoskinson, Reed L. (Rigby, ID); Svoboda, John M. (Idaho Falls, ID); Sawyer, J. Wayne (Hampton, VA); Hess, John R. (Ashton, ID); Hess, J. Richard (Idaho Falls, ID)

2002-01-01T23:59:59.000Z

184

Initial testing of a variable-stroke Stirling engine  

SciTech Connect

In support of the US Department of Energy's Stirling Engine Highway Vehicle Systems Program, NASA Lewis Research Center is evaluating variable-stroke control for Stirling engines. The engine being tested is the Advenco Stirling engine; this engine was manufactured by Philips Research Laboratories of the Netherlands and uses a variable-angle swash-plate drive to achieve variable stroke operation. This report describes the engine, presents initial steady-state test data taken at Lewis, and describes a major drive system failure and subsequent modifications. Computer simulation results are presented to show potential part-load efficiency gains with variable-stroke control.

Thieme, L.G.

1985-02-01T23:59:59.000Z

185

Variability viewpoint to describe reference architectures  

Science Journals Connector (OSTI)

Reference architectures have emerged as a special type of software architecture that achieves well-recognized understanding of specific domains. Their purpose is therefore to be a guidance for the development, standardization, and evolution of systems ... Keywords: architecture description, reference architecture, variability

Milena Guessi; Flavio Oquendo; Elisa Yumi Nakagawa

2014-04-01T23:59:59.000Z

186

Investigations into the effects of environmental and physical variables on the growth of natural and transplanted populations of Ruppia maritima L. s.l. in the Galveston Bay System, Texas.  

E-Print Network (OSTI)

??The effects of sixteen environmental and physical variables on the growth of six natural populations and on the establishment and growth of transplanted populations of… (more)

Schubert, William James

2012-01-01T23:59:59.000Z

187

NERC Presentation: Accommodating High Levels of Variable Generation,  

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

NERC Presentation: Accommodating High Levels of Variable NERC Presentation: Accommodating High Levels of Variable Generation, October 29, 2010 NERC Presentation: Accommodating High Levels of Variable Generation, October 29, 2010 North American Electric Reliability Corporation (NERC) presentation to the Electricity Advisory Committee, October 29, 2010, on accommodating high levels of variable electricity eneration. Variable resources are types of electric power generation that rely on an uncontrolled, "variable" fuel (e.g. wind, sunlight, waves, tidal forces, and some types of rivers) to generate electricity. Most renewablesfall into this category. Reliably integrating these resources into the bulk power system will require significant changes to traditional methods used for system planning and operation. Ongoing efforts brought together by NERC and its stakeholders

188

Orthogonal coordinate systems and separation of variables  

E-Print Network (OSTI)

(u-iv), which, together with equations (2-1), leads to tbe transformation [ei +' 1 + eI -' l] 1 I f (u+iv) - f (u- iv)j 1 2i ! W ~ Then ? = ? Lf'(u+iv) + f'(u-iv)] 3x 1 au 2L du 2i ~ = ? [f ' (u+iv) ? f ' (u-iv)] Qv lr 9 0 8 z 3u ? = ? Lf ' (u...+iv) - f ' (u-iv)] ax i r Qv 2 Sv 2L = ? L f ' (u+iv ) + f ' (u-iv)] 1 I = 0 az 8v ? = 0 Bx Qw a c)w 1 ~ dz = Qw Squaring the ab ove equations and substituting into equations (1-4), we find the scale factors to be h = h = f'(u+~v) f'(u-xv) hs...

Gibbs, Sam Gavin

2012-06-07T23:59:59.000Z

189

The Variable Structure Systems and Cognition  

E-Print Network (OSTI)

Intent ActionApprox. Plan Application New Goal Measured Results Experience Model Refinement Correction Ford Escape Hybrid Regeneration #12;Fuel Economy Hybrid Monthly Fuel Economy Miles Driven Friction

Haykin, Simon

190

PHP: Constructs and Variables Introduction  

E-Print Network (OSTI)

PHP: Constructs and Variables Introduction This document describes: 1. the syntax and types of variables, 2. PHP control structures (i.e., conditionals and loops), 3. mixed-mode processing, 4. how to use one script from within another, 5. how to define and use functions, 6. global variables in PHP, 7

Vander Zanden, Brad

191

Variable Refrigerant Flow HVAC  

E-Print Network (OSTI)

Conference, San Antonio, Texas Dec. 16-18 What do they know that we don’t know? Japan 90% Over 7 Million Systems China 86% Over 17 Million Systems Europe 81% Over 7 Million Systems USA 4% .5 Million Systems ESL-KT-13-12-33 CATEE 2013: Clean Air Through...-source VRF IEER 11.5 - 17.7 19.6 9.7 10.3 10.9 10.5 IPLV - 14.2 - - SCHE - - 18.6 N/A Energy Efficiency - commercial EER ESL-KT-13-12-33 CATEE 2013: Clean Air Through Energy Efficiency Conference, San Antonio, Texas Dec. 16-18 More Comfort & Quiet ? 4 ton...

Jones, S.

2013-01-01T23:59:59.000Z

192

Present and Future Modes of Low Frequency Climate Variability  

SciTech Connect

This project addressed area (1) of the FOA, “Interaction of Climate Change and Low Frequency Modes of Natural Climate Variability”. Our overarching objective is to detect, describe and understand the changes in low frequency variability between model simulations of the preindustrial climate and simulations of a doubled CO2 climate. The deliverables are a set of papers providing a dynamical characterization of interannual, decadal, and multidecadal variability in coupled models with attention to the changes in this low frequency variability between pre-industrial concentrations of greenhouse gases and a doubling of atmospheric concentrations of CO2. The principle mode of analysis, singular vector decomposition, is designed to advance our physical, mechanistic understanding. This study will include external natural variability due to solar and volcanic aerosol variations as well as variability internal to the climate system. An important byproduct is a set of analysis tools for estimating global singular vector structures from the archived output of model simulations.

Cane, Mark A.

2014-02-20T23:59:59.000Z

193

Monitoring variability of multivariate processes  

Science Journals Connector (OSTI)

The paper focuses on determining changes in process variability of multivariate processes. The problem is compounded by the fact that any of the elements in the variance-covariance matrix of variables could change, leading to a change in the process variability. While it may not be feasible to maintain individual control charts for each element of the variance-covariance matrix, some aggregate measure of the variability criteria could be monitored to initially determine if a change has occurred in the process variability. A couple of aggregate measures are proposed and the performance of these suggested measures is explored through a simulation procedure. Compared to the traditional method, which monitors the determinant of the variance-covariance matrix, these alternatives perform well. The performance measure used is the mean time to first detection of a change in the process variability.

Amitava Mitra; Mark Clark

2014-01-01T23:59:59.000Z

194

Interannual Atmospheric Variability Affects Continental Ice Sheet Simulations on Millennial Time Scales  

Science Journals Connector (OSTI)

To inform the ongoing development of earth system models that aim to incorporate interactive ice, the potential impact of interannual variability associated with synoptic variability and El Nińo–Southern Oscillation (ENSO) at the Last Glacial ...

Michael S. Pritchard; Andrew B. G. Bush; Shawn J. Marshall

2008-11-01T23:59:59.000Z

195

Variable Row Spacing of Irrigated Cotton.  

E-Print Network (OSTI)

B-1 lr August 19; aria ble Row Spacing of Irrigated Cotton I as A&M University Texas Agricultural Experiment Station . H. 0. Kunkel, Acting Director, College Station, Texa! Summary Six years' research in the Trans-Pecos area with "variable... row spacing" (VRS), new irrigated cotton row-spacing patterns, is reported. The new system consists of alternate close and ~ricle spaced rows, with narrow irrigation furrows between the close row spacings only. The wide spac- ings serve as dry...

Longenecker, D. E.; Thaxton, E. L. Jr.; Hefner, J. J.; Lyerly, P. J.

1970-01-01T23:59:59.000Z

196

HVAC's Variable Refrigerant Flow (VRF) Technology  

E-Print Network (OSTI)

1 Comfort by Design Steve Jones Commercial Sales Manager for Mitsubishi Southwest Business Unit HVAC?s Variable Refrigerant Flow (VRF) Technology HVAC Industry Overview HVAC Market Dollar Volume $18 Billion Source:;NABH Research....2M Systems Ductless is a small percent of the U.S. HVAC market but current building and energy usage trends indicate a large growth opportunity Determining the Proper Application Worldwide Usage-Opportunity Window Unitary Chillers...

Jones, S.

2012-01-01T23:59:59.000Z

197

Intensive Variables & Nanostructuring in Magnetostructural Materials  

SciTech Connect

Over the course of this project, fundamental inquiry was carried out to investigate, understand and predict the effects of intensive variables, including the structural scale, on magnetostructural phase transitions in the model system of equiatomic FeRh. These transitions comprise simultaneous magnetic and structural phase changes that have their origins in very strong orbital-lattice coupling and thus may be driven by a plurality of effects.

Lewis, Laura

2014-08-13T23:59:59.000Z

198

Selection automatique de variables pertinentes  

E-Print Network (OSTI)

S´election automatique de variables pertinentes Vers la d´ecouverte de nouvelles modalit´es sensori-motrices corr´elations entre ses variables sensori-motrices afin d'apprendre `a r´esoudre sa t^ache d

Boyer, Edmond

199

CX-001530: Categorical Exclusion Determination | Department of...  

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

on existing structures); JJC Day Room Variable Air Volume (VAV) Retrofit; Central Library Air Handler Replacement; Library Heating, Ventilating, and Air Conditioning (HVAC)...

200

Globally competitive variable-speed wind turbines  

SciTech Connect

This paper focuses on the design issues which must be addressed if variable-speed wind turbines are to compete in the global marketplace. The paper examines how component-specific design decisions must be made on a system level if an optimized system is to be the result. The relationships among the blades, the generator and the utility interface are considered in detail, using the conceptual design of a 12 kW variable-speed wind turbine (the AOC 8/12) as a running example. The turbine is based on a direct-drive variable-reluctance generator (VRG), a single- or three-phase utility interface as appropriate, and a three-bladed rotor with fixed pitch. A preliminary turbine specification is provided, along with candidate power-speed curves and annual energy output. This paper documents the continuing development and commercialization of this technology which is being taken from the proof-of-concept stage and is now headed for field testing.

Torrey, D.A. [Rensselaer Polytechnic Institute, Troy, NY (United States); Childs, S.E.; Johnson, B.; Carter, J. [Atlantic Orient Corp., Norwich, VT (United States)

1995-12-31T23:59:59.000Z

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


201

Flex Fuel Vehicle Systems  

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

& Variable Advanced Management Injection Injection Sensors Control Units Fuel Supply & Plastic Parts Control Transmission Engineering Gasoline Systems GSENS, GSENS-NA System...

202

Gas for Balancing of Variable Power Generation; Gas för balansering av varierande elproduktion.  

E-Print Network (OSTI)

?? With the increasing share of variable renewable generation, balancing electric powersystems could become a major concern for system operators because of their variableand hardly… (more)

Bortot, Baptiste

2014-01-01T23:59:59.000Z

203

E-Print Network 3.0 - antibody variable fragment Sample Search...  

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

of A random variables drawn from the distribution G, A being the size of the antibody library. The probability... How the immune system generates diversity: Pathogen space...

204

Market Characteristics for Efficient Integration of Variable Generation in the Western Interconnection  

SciTech Connect

The overriding purpose of this report is to establish the physical requirements of a power system that can accommodate high levels of variable generation.

Milligan, M.; Kirby, B.

2010-08-01T23:59:59.000Z

205

Market Designs for High Levels of Variable Generation: Preprint  

SciTech Connect

Variable renewable generation is increasing in penetration in modern power systems, leading to higher variability in the supply and price of electricity as well as lower average spot prices. This raises new challenges, particularly in ensuring sufficient capacity and flexibility from conventional technologies. Because the fixed costs and lifetimes of electricity generation investments are significant, designing markets and regulations that ensure the efficient integration of renewable generation is a significant challenge. This papers reviews the state of play of market designs for high levels of variable generation in the United States and Europe and considers new developments in both regions.

Milligan, M.; Holttinen, H.; Kiviluoma, J.; Orths, A.; Lynch, M.; Soder, L.

2014-10-01T23:59:59.000Z

206

Advanced Variable Speed Air-Source Integrated Heat Pump  

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

variable speed air-source variable speed air-source integrated heat pump (AS-IHP) - CRADA Van D. Baxter Oak Ridge National Laboratory vdb@ornl.gov; 865-574-2104 April 3, 2013 Development of advanced HVAC/WH system options for efficient residential or small commercial buildings, new const. or retrofit * ET R&D project in support of DOE/BTO Goal of 50% Reduction in Building Energy Use by 2030 IHP concept - all HVAC & WH services integrated into

207

Advanced Variable Speed Air-Source Integrated Heat Pump  

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

variable speed air-source variable speed air-source integrated heat pump (AS-IHP) - CRADA Van D. Baxter Oak Ridge National Laboratory vdb@ornl.gov; 865-574-2104 April 3, 2013 Development of advanced HVAC/WH system options for efficient residential or small commercial buildings, new const. or retrofit * ET R&D project in support of DOE/BTO Goal of 50% Reduction in Building Energy Use by 2030 IHP concept - all HVAC & WH services integrated into

208

A thermodynamics based analysis of exergy destruction in vapor compression cycle systems.  

E-Print Network (OSTI)

??In the last few decades, vapor-compression cycle systems (VCSs) have undergone many advances in actuation, allowing for variable aperture valves, variable speed compressors, and variable… (more)

Kania, Megan

2013-01-01T23:59:59.000Z

209

Reading with fixed and variable character pitch  

Science Journals Connector (OSTI)

We compared the effects of fixed and variable (proportional) spacing on reading speeds and found variable pitch to yield better performance at medium and large character sizes and...

Arditi, Aries; Knoblauch, Kenneth; Grunwald, Ilana

1990-01-01T23:59:59.000Z

210

Cosmological models with variable constants  

E-Print Network (OSTI)

The behavior of the constants, G,c,h,a,e,m and Lambda, considering them as variable, in the framework of a flat cosmological model with FRW symmetries described by a bulk viscous fluid and considering mechanisms of adiabatic matter creation are investigated. Within two models; one with radiation predominance and another of matter predominance, this behavior are studied.

J. A. Belinchon

1999-07-01T23:59:59.000Z

211

Free piston variable-stroke linear-alternator generator  

DOE Patents (OSTI)

A free-piston variable stroke linear-alternator AC power generator for a combustion engine is described. An alternator mechanism and oscillator system generates AC current. The oscillation system includes two oscillation devices each having a combustion cylinder and a flying turnbuckle. The flying turnbuckle moves in accordance with the oscillation device. The alternator system is a linear alternator coupled between the two oscillation devices by a slotted connecting rod. 8 figs.

Haaland, C.M.

1998-12-15T23:59:59.000Z

212

Exploring the Variable Sky with the Sloan Digital Sky Survey  

E-Print Network (OSTI)

We quantify the variability of faint unresolved optical sources using a catalog based on multiple SDSS imaging observations. The catalog covers SDSS Stripe 82, and contains 58 million photometric observations in the SDSS ugriz system for 1.4 million unresolved sources. In each photometric bandpass we compute various low-order lightcurve statistics and use them to select and study variable sources. We find that 2% of unresolved optical sources brighter than g=20.5 appear variable at the 0.05 mag level (rms) simultaneously in the g and r bands. The majority (2/3) of these variable sources are low-redshift (<2) quasars, although they represent only 2% of all sources in the adopted flux-limited sample. We find that at least 90% of quasars are variable at the 0.03 mag level (rms) and confirm that variability is as good a method for finding low-redshift quasars as is the UV excess color selection (at high Galactic latitudes). We analyze the distribution of lightcurve skewness for quasars and find that is centered on zero. We find that about 1/4 of the variable stars are RR Lyrae stars, and that only 0.5% of stars from the main stellar locus are variable at the 0.05 mag level. The distribution of lightcurve skewness in the g-r vs. u-g color-color diagram on the main stellar locus is found to be bimodal (with one mode consistent with Algol-like behavior). Using over six hundred RR Lyrae stars, we demonstrate rich halo substructure out to distances of 100 kpc. We extrapolate these results to expected performance by the Large Synoptic Survey Telescope and estimate that it will obtain well-sampled 2% accurate, multi-color lightcurves for ~2 million low-redshift quasars, and will discover at least 50 million variable stars.

Branimir Sesar; Zeljko Ivezic; Robert H. Lupton; Mario Juric; James E. Gunn; Gillian R. Knapp; Nathan De Lee; J. Allyn Smith; Gajus Miknaitis; Huan Lin; Douglas Tucker; Mamoru Doi; Masayuki Tanaka; Masataka Fukugita; Jon Holtzman; Steve Kent; Brian Yanny; David Schlegel; Douglas Finkbeiner; Nikhil Padmanabhan; Constance M. Rockosi; Nicholas Bond; Brian Lee; Chris Stoughton; Sebastian Jester; Hugh Harris; Paul Harding; Jon Brinkmann; Donald P. Schneider; Donald York; Michael W. Richmond; Daniel Vanden Berk

2007-04-04T23:59:59.000Z

213

MID-INFRARED SPECTRAL VARIABILITY ATLAS OF YOUNG STELLAR OBJECTS  

SciTech Connect

Optical and near-infrared variability is a well-known property of young stellar objects. However, a growing number of recent studies claim that a considerable fraction of them also exhibit mid-infrared flux changes. With the aim of studying and interpreting variability on a decadal timescale, here we present a mid-infrared spectral atlas containing observations of 68 low- and intermediate-mass young stellar objects. The atlas consists of 2.5-11.6 {mu}m low-resolution spectra obtained with the ISOPHOT-S instrument on board the Infrared Space Observatory (ISO) between 1996 and 1998, as well as 5.2-14.5 {mu}m low-resolution spectra obtained with the Infrared Spectrograph instrument on board the Spitzer Space Telescope between 2004 and 2007. The observations were retrieved from the ISO and Spitzer archives and were post-processed interactively by our own routines. For those 47 objects where multi-epoch spectra were available, we analyze mid-infrared spectral variability on annual and/or decadal timescales. We identify 37 variable candidate sources. Many stars show wavelength-independent flux changes, possibly due to variable accretion rates. In several systems, all exhibiting 10 {mu}m silicate emission, the variability of the 6-8 {mu}m continuum, and the silicate feature exhibit different amplitudes. A possible explanation is variable shadowing of the silicate-emitting region by an inner disk structure of changing height or extra silicate emission from dust clouds in the disk atmosphere. Our results suggest that mid-infrared variability, in particular, the wavelength-dependent changes, is more ubiquitous than was known before. Interpreting this variability is a new possibility for exploring the structure of the disk and its dynamical processes.

Kospal, A. [Leiden Observatory, Leiden University, P.O. Box 9513, 2300 RA, Leiden (Netherlands); Abraham, P.; Kun, M.; Moor, A. [Konkoly Observatory, Research Centre for Astronomy and Earth Sciences, Hungarian Academy of Sciences, P.O. Box 67, 1525 Budapest (Hungary); Acosta-Pulido, J. A. [Instituto de Astrofisica de Canarias, Via Lactea s/n, 38200 La Laguna, Tenerife (Spain); Dullemond, C. P. [Institut fuer Theoretische Astrophysik, Zentrum fuer Astronomie der Universitaet Heidelberg, Albert-Ueberle-Str. 2, 69120 Heidelberg (Germany); Henning, Th.; Leinert, Ch. [Max-Planck-Institut fuer Astronomie, Koenigstuhl 17, 69117 Heidelberg (Germany); Turner, N. J., E-mail: akospal@rssd.esa.int [Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109 (United States)

2012-08-01T23:59:59.000Z

214

The Value of a Variable Resolution Approach to Numerical Weather Prediction  

Science Journals Connector (OSTI)

It is shown that a numerical weather prediction system with variable resolution, higher in the early forecast range and lower afterward, provides more skilful forecasts than a system with constant resolution. Results indicate that the advantage ...

Roberto Buizza

2010-04-01T23:59:59.000Z

215

Massive Variability Surveys from Venezuela  

E-Print Network (OSTI)

At the Venezuela National Astronomical Observatory we are carrying out variability surveys spanning many hundreds of square degrees near the celestial equator, using an 8k x 8k CCD Mosaic Camera optimized for drift-scanning on a 1m Schmidt telescope. Among the initial efforts was a project to obtain the first moderately deep, homogeneous sample of young stars over an area of ~180sqr.deg. encompassing the entire Orion OB1 association, one of the nearest and most active regions of star formation. The results show that variability is a powerful technique to identify pre-main sequence populations, specially in sparse areas devoid of gas and dust. We are currently developing a massive database, equipped with web-based data mining tools, that will make our data and results available to the astronomical community.

Cesar Briceno

2003-04-03T23:59:59.000Z

216

Variable frequency microwave heating apparatus  

DOE Patents (OSTI)

A variable frequency microwave heating apparatus (10) designed to allow modulation of the frequency of the microwaves introduced into a multi-mode microwave cavity (34) for testing or other selected applications. The variable frequency microwave heating apparatus (10) includes a microwave signal generator (12) and a high-power microwave amplifier (20) or a high-power microwave oscillator (14). A power supply (22) is provided for operation of the high-power microwave oscillator (14) or microwave amplifier (20). A directional coupler (24) is provided for detecting the direction and amplitude of signals incident upon and reflected from the microwave cavity (34). A first power meter (30) is provided for measuring the power delivered to the microwave furnace (32). A second power meter (26) detects the magnitude of reflected power. Reflected power is dissipated in the reflected power load (28).

Bible, Don W. (Clinton, TN); Lauf, Robert J. (Oak Ridge, TN); Johnson, Arvid C. (Lake in the Hills, IL); Thigpen, Larry T. (Angier, NC)

1999-01-01T23:59:59.000Z

217

Review of Probability Random Variable  

E-Print Network (OSTI)

at close 4) Height of wheel going over a rocky road #12;3 Random Variable Non-examples 1) `Heads' or `Tails' on coin 2) Red or Black ball from urn But we can make these into RV's Basic Idea ­ don't know · Temperature · Wheel height #12;5 Given Continuous RV X... What is the probability that X = x0 ? Oddity : P

Fowler, Mark

218

On Target: A Complicated and Successful Energy Retrofit Program  

E-Print Network (OSTI)

, using single effect absorption chillers, a 2-pipe hydronic exterior zone system with nearly 600 air induction units, and "state of the art" variable air volume (VAV) technology was installed in the North and South buildings in 1949. During mid 1960.... The plant then consisted of four absorption chillers of 1367 tons on a primary chillwater loop with seven separate secondary loops serving the various zones in the Park St., West, North, and South buildings, and approximately 1700 tons of cooling tower...

Kimball, M. A.

1996-01-01T23:59:59.000Z

219

IMPROVED BOUSSINESQ-TYPE EQUATIONS FOR HIGHLY-VARIABLE DEPTH  

E-Print Network (OSTI)

IMPROVED BOUSSINESQ-TYPE EQUATIONS FOR HIGHLY-VARIABLE DEPTH JUAN CARLOS MU~NOZ GRAJALES AND ANDR´E NACHBIN Abstract. Intermediate depth, Boussinesq-type modeling is used to generalize previously known are extended from the analysis of KdV-type models to include the improved Boussinesq systems in contrast

Nachbin, André

220

Essential Terrestrial Variable data workflows for distributed water resources modeling  

Science Journals Connector (OSTI)

This paper discusses a prototype infrastructure, HydroTerre, that provides researchers, educators and resource managers with seamless access to geospatial/geotemporal data for supporting physics-based numerical models. The prototype defines the supporting ... Keywords: Data workflow, Distributed hydrologic model, Essential Terrestrial Variables, Geographic information systems, HydroTerre, PIHM, Web services

Lorne Leonard; Christopher J. Duffy

2013-12-01T23:59:59.000Z

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


221

Best Practices for Energy Efficient Cleanrooms: Variable Speed Pumping  

E-Print Network (OSTI)

efficiency of chilled water and condenser pumps, along with chiller efficiency and cooling tower efficiency, operate, and control water-pumping systems to achieve high efficiency and to lower life-cycle costsLBNL-58637 Best Practices for Energy Efficient Cleanrooms: Variable Speed Pumping Tengfang Xu June

222

HEART RATE VARIABILITY AS DETERMINISM WITH JUMP STOCHASTIC PARAMETERS  

E-Print Network (OSTI)

HEART RATE VARIABILITY AS DETERMINISM WITH JUMP STOCHASTIC PARAMETERS JIONGXUAN ZHENG, JOE SKUFCA, AND ERIK BOLLT§ Abstract. We use measured heart rate information (RR intervals) to develop a one with persistence which causes the heart rate and rhythm system to wander about a bifurcation point. We propose

Bollt, Erik

223

Variable-energy drift-tube linear accelerator  

DOE Patents (OSTI)

A linear accelerator system includes a plurality of post-coupled drift-tubes wherein each post coupler is bistably positionable to either of two positions which result in different field distributions. With binary control over a plurality of post couplers, a significant accumlative effect in the resulting field distribution is achieved yielding a variable-energy drift-tube linear accelerator.

Swenson, Donald A. (Los Alamos, NM); Boyd, Jr., Thomas J. (Los Alamos, NM); Potter, James M. (Los Alamos, NM); Stovall, James E. (Los Alamos, NM)

1984-01-01T23:59:59.000Z

224

Eclipsing Binaries in the OGLE Variable Star Catalogs.V. Long-Period Beta Lyrae-type Systems in the Small Magellanic Cloud and the PLC-beta Relation  

E-Print Network (OSTI)

Thirty eight long-period (P>10 days), apparently contact binary stars discovered by the OGLE-II project in the SMC appear to be Beta Lyrae-type systems with ellipsoidal variations of the cool components dominating over eclipse effects in the systemic light variations and in the total luminosity. A new period-luminosity- color (PLC) relation has been established for these systems; we call it the PLC-beta relation, to distinguish it from the Cepheid relation. Two versions of the PLC-beta relation - based on the (B-V)0 or (V-I)0 color indices - have been calibrated for 33 systems with (V-I)0>0.25 spanning the orbital period range of 11 to 181 days. The relations can provide maximum-light, absolute-magnitude estimates accurate to epsilon-M_V~0.35 mag. within the approximate range -3PLC-beta relation can offer an auxiliary and entirely independent method of distance determination to nearby stellar systems rich in massive stars. The sample of the long-period Beta Lyrae systems in the SMC analyzed in this paper is currently the best defined and uniform known sequence of such binaries.

Slavek M. Rucinski; Carla Maceroni

2000-06-16T23:59:59.000Z

225

Variable pressure operation: An assessment  

SciTech Connect

This report summarizes the benefits, drawbacks, and technical issues of variable pressure operation (VPO) retrofit. Under VPO, turbine throttle pressure is reduced at low loads. This operating mode offers several significant advantages for units that cycle or operate at low loads for extended periods. Information used in the report was assembled from published sources, from major equipment manufacturers, and from utilities operating units under VPO in the US, Europe and Japan. The report also contains statistics of VPO use in this country and abroad. Design features of new units using VPO in Europe and Japan are presented to identify potential directions for future US designs incorporating VPO.

Kimel, E.; Kemeny, P.; Bierman, E.; Lagomarsino, J.; Clarke, D. (Burns and Roe, Inc., Oradell, NJ (USA))

1990-03-01T23:59:59.000Z

226

Mass Market Demand Response and Variable Generation Integration Issues: A Scoping Study  

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

Mass Market Demand Response and Mass Market Demand Response and Mass Market Demand Response and Mass Market Demand Response and Variable Generation Integration Issues: Variable Generation Integration Issues: Variable Generation Integration Issues: Variable Generation Integration Issues: A Scoping Study A Scoping Study Peter Cappers, Andrew Mills, Charles Goldman, Ryan Wiser, Joseph H. Eto Report Summary October 2011 Energy Analysis Department  Electricity Markets and Policy Group 1 1 Presentation Overview Presentation Overview  Objectives and Approach  Variable Generation Resources and the Bulk Power System  Demand Response Opportunities  Demand Response as a Strategy to Integrate p gy g Variable Generation Resources  Comparison of Various Strategies to Integrate Variable Generation  Conclusions Energy Analysis Department  Electricity Markets and Policy Group

227

Advanced Variable Speed Air-Source Integrated Heat Pumps Research Project |  

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

Advanced Variable Speed Air-Source Advanced Variable Speed Air-Source Integrated Heat Pumps Research Project Advanced Variable Speed Air-Source Integrated Heat Pumps Research Project The U.S. Department of Energy is currently conducting research into advanced variable speed air-source integrated heat pumps (AS-IHPs). Project Description This project seeks to develop AS-IHP products for the larger air-source system market. Development focuses on a fully variable capacity or variable speed AS-IHP option. Project Partners Research is being undertaken through a cooperative research and development agreement (CRADA) between the Department of Energy, Oak Ridge National Laboratory, and a CRADA partner. Project Goals The goal of this project is the development of a fully variable-speed version of an AS-IHP product that can provide heating, ventilation, and air

228

A group bridge approach for variable selection  

Science Journals Connector (OSTI)

......group bridge approach for variable...Actuarial Science, University...Department of Management Science, University...group bridge approach that is capable...group bridge approach for variable...Actuarial Science, University...Department of Management Science......

Jian Huang; Shuange Ma; Huiliang Xie; Cun-Hui Zhang

2009-06-01T23:59:59.000Z

229

Variable Average Absolute Percent Differences  

U.S. Energy Information Administration (EIA) Indexed Site

Variable Variable Average Absolute Percent Differences Percent of Projections Over- Estimated Gross Domestic Product Real Gross Domestic Product (Average Cumulative Growth)* (Table 2) 1.0 42.6 Petroleum Imported Refiner Acquisition Cost of Crude Oil (Constant $) (Table 3a) 35.2 18.6 Imported Refiner Acquisition Cost of Crude Oil (Nominal $) (Table 3b) 34.7 19.7 Total Petroleum Consumption (Table 4) 6.2 66.5 Crude Oil Production (Table 5) 6.0 59.6 Petroleum Net Imports (Table 6) 13.3 67.0 Natural Gas Natural Gas Wellhead Prices (Constant $) (Table 7a) 30.7 26.1 Natural Gas Wellhead Prices (Nominal $) (Table 7b) 30.0 27.1 Total Natural Gas Consumption (Table 8) 7.8 70.2 Natural Gas Production (Table 9) 7.1 66.0 Natural Gas Net Imports (Table 10) 29.3 69.7 Coal Coal Prices to Electric Generating Plants (Constant $)** (Table 11a)

230

Instantaneous Measurement of Nonlocal Variables Lev Vaidman  

E-Print Network (OSTI)

Instantaneous Measurement of Nonlocal Variables Lev Vaidman 1 School of Physics and Astronomy variables related to two or more separate sites can be measured instantaneously, except for a finite time of the measurement. It is a verification measurement: it yields reliably the eigenvalues of the nonlocal variables

Vaidman, Lev

231

Integration of Variable Generation and Cost-Causation (Fact Sheet)  

SciTech Connect

Variable renewable energy generation sources, such as wind and solar energy, provide benefits such as reduced environmental impact, zero fuel consumption, and low and stable costs. Advances in both technologies can reduce capital costs and provide significant control capabilities. However, their variability and uncertainty - which change with weather conditions, time of day, and season - can cause an increase in power system operating costs compared to a fully controllable power plant. Although a number of studies have assessed integration costs, calculating them correctly is challenging because it is difficult to accurately develop a baseline scenario without variable generation that properly accounts for the energy value. It is also difficult to appropriately allocate costs given the complex, nonlinear interactions between resources and loads.

Not Available

2012-09-01T23:59:59.000Z

232

GD 552: a cataclysmic variable with a brown dwarf companion?  

E-Print Network (OSTI)

GD 552 is a high proper motion star with the strong, double-peaked emission lines characteristic of the dwarf nova class of cataclysmic variable star, and yet no outburst has been detected during the past 12 years of monitoring. We present spectroscopy taken with the aim of detecting emission from the mass donor in this system. We fail to do so at a level which allows us to rule out the presence of a near-main-sequence star donor. Given GD 552's orbital period of 103 minutes, this suggests that it is either a system that has evolved through the ~80-minute orbital period minimum of cataclysmic variable stars and now has a brown dwarf mass donor, or that has formed with a brown dwarf donor in the first place. This model explains the low observed orbital velocity of the white dwarf and GD 552's low luminosity. It is also consistent with the absence of outbursts from the system.

E. Unda-Sanzana; T. R. Marsh; B. T. Gansicke; P. F. L. Maxted; L. Morales-Rueda; V. S. Dhillon; T. D. Thoroughgood; E. Tremou; C. A. Watson; R. Hinojosa-Goni

2008-06-30T23:59:59.000Z

233

Variable White Dwarf Data Tables  

SciTech Connect

Below, I give a brief explanation of the information in these tables. In all cases, I list the WD {number_sign}, either from the catalog of McCook {ampersand} Sion (1987) or determined by me from the epoch 1950 coordinates. Next, I list the most commonly used name (or alias), then I list the variable star designation if it is available. If not, I list the constellation name and a V** or?? depending on what the last designated variable star for that constellation is. I present epoch 2000 coordinates for all of the stars, which I precessed from the 1950 ones in most cases. I do not include proper motion effects; this is negligible for all except the largest proper motion DAV stars, such as L 19-2, BPM 37093, B 808, and G 29-38. Even in these cases, the error is no more than 30` in declination and 2 s in right ascension. I culled effective temperatures from the latest work (listed under each table); they are now much more homogeneous than before. I pulled the magnitude estimates from the appropriate paper, and they are mean values integrated over several cycles. The amplitude given is for the height of a typical pulse in the light curve. The periods correspond the dominant ones found in the light curve. In some cases, there is a band of power in a given period range, or the light curve is very complex, and I indicate this in the table. In the references, I generally list the paper with the most comprehensive pulsation analysis for the star in question. In some cases, there is more than one good reference, and I list them as well.

Bradley, P. A.

1997-12-31T23:59:59.000Z

234

The Impacts of Wind Speed Trends and Long-term Variability in Relation to Hydroelectric  

E-Print Network (OSTI)

The Impacts of Wind Speed Trends and Long- term Variability in Relation to Hydroelectric Reservoir and Long-term Variability in Relation to Hydroelectric Reservoir Inflows on Wind Power in the Pacific through diversification. In hydroelectric dominated systems, like the PNW, the benefits of wind power can

Kohfeld, Karen

235

Thermodynamics of the Universe Filled with Perfect Fluid Having Variable Equation of State  

E-Print Network (OSTI)

We study the thermodynamics of the universe containing perfect fluid with equation of state $p=\\omega\\rho,\\omega$ is variable. Here we choose $\\omega$ to be a function of the red shift variable $z$ and four different choices of $\\omega$ has been investigated. Also the laws of thermodynamics are examined considering the universe bounded by the horizon (apparent) as a thermodynamical system.

Nairwita Mazumder; Subenoy Chakraborty

2009-07-16T23:59:59.000Z

236

ESTIMATION OF EXHAUST MANIFOLD PRESSURE IN TURBOCHARGED GASOLINE ENGINES WITH VARIABLE VALVE TIMING  

E-Print Network (OSTI)

ESTIMATION OF EXHAUST MANIFOLD PRESSURE IN TURBOCHARGED GASOLINE ENGINES WITH VARIABLE VALVE TIMING in turbocharged gasoline engines with variable valve timing requires knowledge of exhaust mani- fold pressure, Pe control systems for gasoline engines rely heavily on feedforward air-fuel ratio (A/F) control to meet

Grizzle, Jessy W.

237

Glossary | Building Energy Codes Program  

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

Balancing, Air Balancing, Air Adjusting air flow rates through air distribution system devices, such as fans and diffusers, by manually adjusting the position of dampers, splitter vanes, extractors, etc., or by using automatic control devices, such as constant air volume or variable air volume boxes. Balancing, Hydronic Adjusting water flow rates through hydronic distribution system devices, such as pumps and coils, by manually adjusting the position valves, or by using automatic control devices, such as automatic flow control valves. Ballast A device used in conjunction with an electric-discharge lamp to cause the lamp to start and operate under the proper circuit conditions of voltage, current, wave form, electrode heat, etc. Basement Wall Basement walls that enclose heated spaces are part of the building

238

Variability of Load and Net Load in Case of Large Scale Distributed Wind Power  

SciTech Connect

Large scale wind power production and its variability is one of the major inputs to wind integration studies. This paper analyses measured data from large scale wind power production. Comparisons of variability are made across several variables: time scale (10-60 minute ramp rates), number of wind farms, and simulated vs. modeled data. Ramp rates for Wind power production, Load (total system load) and Net load (load minus wind power production) demonstrate how wind power increases the net load variability. Wind power will also change the timing of daily ramps.

Holttinen, H.; Kiviluoma, J.; Estanqueiro, A.; Gomez-Lazaro, E.; Rawn, B.; Dobschinski, J.; Meibom, P.; Lannoye, E.; Aigner, T.; Wan, Y. H.; Milligan, M.

2011-01-01T23:59:59.000Z

239

Variable-amplitude oscillatory shear response of amorphous materials  

E-Print Network (OSTI)

Variable-amplitude oscillatory shear tests are emerging as powerful tools to investigate and quantify the nonlinear rheology of amorphous solids, complex fluids and biological materials. Quite a few recent experimental and atomistic simulation studies demonstrated that at low shear amplitudes, an amorphous solid settles into an amplitude- and initial conditions-dependent dissipative limit cycle, in which back-and-forth localized particle rearrangements periodically bring the system to the same state. At sufficiently large shear amplitudes, the amorphous system loses memory of the initial conditions, exhibits chaotic particle motions accompanied by diffusive behavior and settles into a stochastic steady-state. The two regimes are separated by a transition amplitude, possibly characterized by some critical-like features. Here we argue that these observations support some of the physical assumptions embodied in the nonequilibrium thermodynamic, internal-variables based, Shear-Transformation-Zone model of amorphous visco-plasticity; most notably that "flow defects" in amorphous solids are characterized by internal states between which they can make transitions, and that structural evolution is driven by dissipation associated with plastic deformation. We present a rather extensive theoretical analysis of the thermodynamic Shear-Transformation-Zone model for a variable-amplitude oscillatory shear protocol, highlighting its success in accounting for various experimental and simulational observations, as well as its limitations. Our results offer a continuum-level theoretical framework for interpreting the variable-amplitude oscillatory shear response of amorphous solids and may promote additional developments.

Nathan Perchikov; Eran Bouchbinder

2014-04-13T23:59:59.000Z

240

Variable path length spectrophotometric probe  

DOE Patents (OSTI)

A compact, variable pathlength, fiber optic probe for spectrophotometric measurements of fluids in situ. The probe comprises a probe body with a shaft having a polished end penetrating one side of the probe, a pair of optic fibers, parallel and coterminous, entering the probe opposite the reflecting shaft, and a collimating lens to direct light from one of the fibers to the reflecting surface of the shaft and to direct the reflected light to the second optic fiber. The probe body has an inlet and an outlet port to allow the liquid to enter the probe body and pass between the lens and the reflecting surface of the shaft. A linear stepper motor is connected to the shaft to cause the shaft to advance toward or away from the lens in increments so that absorption measurements can be made at each of the incremental steps. The shaft is sealed to the probe body by a bellows seal to allow freedom of movement of the shaft and yet avoid leakage from the interior of the probe.

O'Rourke, Patrick E. (157 Greenwood Dr., Martiney, GA 30907); McCarty, Jerry E. (104 Recreation Dr., Aiken, SC 29803); Haggard, Ricky A. (1144 Thornwood Drive, North Augusta, SC 29891)

1992-01-01T23:59:59.000Z

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


241

HERSCHEL OBSERVATIONS OF CATACLYSMIC VARIABLES  

SciTech Connect

We have used the PACS instrument on the Herschel Space Observatory to observe eight cataclysmic variables at 70 and 160 {mu}m. Of these eight objects, only AM Her was detected. We have combined the Herschel results with ground-based, Spitzer, and WISE observations to construct spectral energy distributions for all of the targets. For the two dwarf novae in the sample, SS Cyg and U Gem, we find that their infrared luminosities are completely dominated by their secondary stars. For the two highly magnetic 'polars' in our survey, AM Her and EF Eri, we find that their mid-infrared excesses, previously attributed to circumbinary dust emission, can be fully explained by cyclotron emission. The WISE light curves for both sources show large, orbitally modulated variations that are identically phased to their near-IR light curves. We propose that significant emission from the lowest cyclotron harmonics (n {<=} 3) is present in EF Eri and AM Her. Previously, such emission would have been presumed to be optically thick, and not provide significant orbitally modulated flux. This suggests that the accretion onto polars is more complicated than assumed in the simple models developed for these two sources. We develop a model for the near-/mid-IR light curves for WZ Sge with an L2 donor star that shows that the ellipsoidal variations from its secondary star are detected. We conclude that none of the targets surveyed have dusty circumbinary disks.

Harrison, Thomas E.; Hamilton, Ryan T. [Department of Astronomy, New Mexico State University, Box 30001, MSC 4500, Las Cruces, NM 88003-8001 (United States); Tappert, Claus [Departamento de Fisica y Astronomia, Universidad de Valparaiso, Avda. Gran Bretana 1111, Valparaiso (Chile); Hoffman, Douglas I. [Infrared Processing and Analysis Center, California Institute of Technology, Pasadena, CA 91125 (United States); Campbell, Ryan K., E-mail: tharriso@nmsu.edu, E-mail: rthamilt@nmsu.edu, E-mail: claus.tappert@uv.cl, E-mail: dhoffman@ipac.caltech.edu, E-mail: Ryan.Campbell@humobldt.edu [Department of Physics and Astronomy, Humboldt State University, 1 Harpst St., Arcata, CA 95521 (United States)

2013-01-01T23:59:59.000Z

242

Definition: Variable Peak Pricing | Open Energy Information  

Open Energy Info (EERE)

Variable Peak Pricing Variable Peak Pricing Jump to: navigation, search Dictionary.png Variable Peak Pricing Variable Peak Pricing (VPP) is a hybrid of time-of-use and real-time pricing where the different periods for pricing are defined in advance (e.g., on-peak=6 hours for summer weekday afternoon; off-peak= all other hours in the summer months), but the price established for the on-peak period varies by utility and market conditions.[1] Related Terms real-time pricing References ↑ https://www.smartgrid.gov/category/technology/variable_peak_pricing [[C LikeLike UnlikeLike You like this.Sign Up to see what your friends like. ategory: Smart Grid Definitionssmart grid,off-peak,on-peak,smart grid, |Template:BASEPAGENAME]]smart grid,off-peak,on-peak,smart grid, Retrieved from "http://en.openei.org/w/index.php?title=Definition:Variable_Peak_Pricing&oldid=50262

243

Effect of lecturing to 200 students on heart rate variability and alpha-amylase activity  

Science Journals Connector (OSTI)

The aim of this study was to examine cardiovascular [heart rate variability (HRV)] and autonomic nervous system activation (by evaluating salivary alpha-amylase activity) that occur in professors both to...P ...

Edith Filaire; Hugues Portier; Alain Massart…

2010-03-01T23:59:59.000Z

244

Experimental Verification of a Mass Measurement Device under Zero Gravity with a Prismatic Variable Stiffness Mechanism  

Science Journals Connector (OSTI)

A new method to measure the mass of an object in microgravity is proposed in this paper. The proposed method uses a new system that consists of a prismatic variable stiffness mechanism and an actuator. The obj...

Ryota Ishibashi; Ryuta Ozawa; Sadao Kawamura

2010-01-01T23:59:59.000Z

245

Direct comparison of Neural Network, Fuzzy Logic and Model Prediction Variable Structure vortex flow controllers  

E-Print Network (OSTI)

Predictive Variable Structure and Fuzzy Logic based controllers for the same benchmark problem. Evaluation criteria consist of closed-loop system performance, activity level of the VFC nozzles, ease of controller synthesis, time required to synthesize...

Joshi, Praveen Sudhakar

2012-06-07T23:59:59.000Z

246

Estimation and Control of Diesel Engine Processes Utilizing Variable Intake Valve Actuation  

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

Air handling system model for multi-cylinder variable geometry turbocharged diesel engine with cooled EGR and flexible intake valve actuation developed to capture dynamic effects of gas exchange actuators

247

Development of an infrared absorption spectroscope based on linear variable filters  

E-Print Network (OSTI)

and used as independent variables. We characterize the system on a number of performance metrics, uncovering its detection limits and resolving power. We present calibration methods to estimate the concentration of analytes in a matrix of absorbing species...

Nogueira, Felipe Guimaraes

2009-05-15T23:59:59.000Z

248

String Method with Collective variables from Normal Modes : Application to Alanine Dipeptide  

E-Print Network (OSTI)

approximation of the original system. To obtain the eigenvectors/eigen- values that are ordered according. In this paper, we present a method of semi-automatically determining collective variable set which can be used

Izaguirre, JesĂşs A.

249

Variable-Period Undulators for Synchrotron Radiation  

SciTech Connect

A new and improved undulator design is provided that enables a variable period length for the production of synchrotron radiation from both medium-energy and high energy storage rings. The variable period length is achieved using a staggered array of pole pieces made up of high permeability material, permanent magnet material, or an electromagnetic structure. The pole pieces are separated by a variable width space. The sum of the variable width space and the pole width would therefore define the period of the undulator. Features and advantages of the invention include broad photon energy tunability, constant power operation and constant brilliance operation.

Shenoy, Gopal; Lewellen, John; Shu, Deming; Vinokurov, Nikolai

2005-02-22T23:59:59.000Z

250

Multivector Functions of a Real Variable  

E-Print Network (OSTI)

This paper is an introduction to the theory of multivector functions of a real variable. The notions of limit, continuity and derivative for these objects are given. The theory of multivector functions of a real variable, even being similar to the usual theory of vector functions of a real variable, has some subtle issues which make its presentation worhtwhile.We refer in particular to the derivative rules involving exterior and Clifford products, and also to the rule for derivation of a composition of an ordinary scalar function with a multivector function of a real variable.

A. M. Moya; V. V. Fernández; W. A. Rodrigues Jr

2002-12-17T23:59:59.000Z

251

Hybrid Bayesian Networks with Linear Deterministic Variables  

E-Print Network (OSTI)

Conference (UAI-05), 2005, AUAI Press, Arlington, VA. 136 Y X Z Figure 2: A Bayesian Network Representation of the Mixed Distribution for X. this example, Y is a discrete variable with state space ? Y = {1,2,3}, Z is a real-valued variable, and X is a... conditionally deterministic variable whose condi- tional distribution is described as follows: X |{y,z} = y if y =1,2 and X |{y,z} = z if y =3. Potentials of the type described above are used in this paper to represent distributions of variables in hy- brid...

Cobb, Barry R.; Shenoy, Prakash P.

2005-07-01T23:59:59.000Z

252

Integrating Variable Renewable Energy: Challenges and Solutions  

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

Integrating Variable Renewable Energy: Challenges and Solutions L. Bird, M. Milligan, and D. Lew National Renewable Energy Laboratory Technical Report NRELTP-6A20-60451 September...

253

U-097: PHP "php_register_variable_ex()" Code Execution Vulnerability |  

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

097: PHP "php_register_variable_ex()" Code Execution 097: PHP "php_register_variable_ex()" Code Execution Vulnerability U-097: PHP "php_register_variable_ex()" Code Execution Vulnerability February 7, 2012 - 9:00am Addthis PROBLEM: PHP "php_register_variable_ex()" Code Execution Vulnerability PLATFORM: PHP 5.3.x ABSTRACT: Execution of arbitrary code via network as well as user access via network reference LINKS: PHP Security Archive SecurityTracker Alert ID: 1026631 Secunia Advisory SA47806 CVE-2012-0830 IMPACT ASSESSMENT: High Discussion: A vulnerability has been reported in PHP, which can be exploited by malicious people to compromise a vulnerable system. Impact: A remote user can send specially crafted data to trigger a memory error in php_register_variable_ex() and execute arbitrary code on the target system.

254

New Report: Integrating Variable Wind Energy into the Grid | Department of  

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

Report: Integrating Variable Wind Energy into the Grid Report: Integrating Variable Wind Energy into the Grid New Report: Integrating Variable Wind Energy into the Grid December 19, 2011 - 2:00pm Addthis The Energy Department and Alstom Grid announce the availability of a new report on integrating wind energy into the electrical grid. | Image source: The Strategies and Decision Support Systems for Integrating Variable Energy Resources in Control Centers for Reliable Grid Operations Report. The Energy Department and Alstom Grid announce the availability of a new report on integrating wind energy into the electrical grid. | Image source: The Strategies and Decision Support Systems for Integrating Variable Energy Resources in Control Centers for Reliable Grid Operations Report. Charlton I. Clark Integration Team Lead, Wind and Water Power Program

255

Envera Variable Compression Ratio Engine  

SciTech Connect

Aggressive engine downsizing, variable compression ratio and use of the Atkinson cycle are being combined to improve fuel economy by up to 40 percent relative to port fuel injected gasoline engines, while maintaining full engine power. Approach Engine downsizing is viewed by US and foreign automobile manufacturers as one of the best options for improving fuel economy. While this strategy has already demonstrated a degree of success, downsizing and fuel economy gains are currently limited. With new variable compression ratio technology however, the degree of engine downsizing and fuel economy improvement can be greatly increased. A small variable compression ratio (VCR) engine has the potential to return significantly higher vehicle fuel economy while also providing high power. Affordability and potential for near term commercialization are key attributes of the Envera VCR engine. VCR Technology To meet torque and power requirements, a smaller engine needs to do more work per stroke. This is typically accomplished by boosting the incoming charge with either a turbo or supercharger so that more energy is present in the cylinder per stroke to do the work. With current production engines the degree of engine boosting (which correlates to downsizing) is limited by detonation (combustion knock) at high boost levels. Additionally, the turbo or supercharger needs to be responsive and efficient while providing the needed boost. VCR technology eliminates the limitation of engine knock at high load levels by reducing compression ratio to {approx}9:1 (or whatever level is appropriate) when high boost pressures are needed. By reducing the compression ratio during high load demand periods there is increased volume in the cylinder at top dead center (TDC) which allows more charge (or energy) to be present in the cylinder without increasing the peak pressure. Cylinder pressure is thus kept below the level at which the engine would begin to knock. When loads on the engine are low the compression ratio can be raised (to as much as 18:1) providing high engine efficiency. It is important to recognize that for a well designed VCR engine cylinder pressure does not need to be higher than found in current production turbocharged engines. As such, there is no need for a stronger crankcase, bearings and other load bearing parts within the VCR engine. The Envera VCR mechanism uses an eccentric carrier approach to adjust engine compression ratio. The crankshaft main bearings are mounted in this eccentric carrier or 'crankshaft cradle' and pivoting the eccentric carrier 30 degrees adjusts compression ratio from 9:1 to 18:1. The eccentric carrier is made up of a casting that provides rigid support for the main bearings, and removable upper bearing caps. Oil feed to the main bearings transits through the bearing cap fastener sockets. The eccentric carrier design was chosen for its low cost and rigid support of the main bearings. A control shaft and connecting links are used to pivot the eccentric carrier. The control shaft mechanism features compression ratio lock-up at minimum and maximum compression ratio settings. The control shaft method of pivoting the eccentric carrier was selected due to its lock-up capability. The control shaft can be rotated by a hydraulic actuator or an electric motor. The engine shown in Figures 3 and 4 has a hydraulic actuator that was developed under the current program. In-line 4-cylinder engines are significantly less expensive than V engines because an entire cylinder head can be eliminated. The cost savings from eliminating cylinders and an entire cylinder head will notably offset the added cost of the VCR and supercharging. Replacing V6 and V8 engines with in-line VCR 4-cylinder engines will provide high fuel economy at low cost. Numerous enabling technologies exist which have the potential to increase engine efficiency. The greatest efficiency gains are realized when the right combination of advanced and new technologies are packaged together to provide the greatest gains at the least cost. Aggressive engine downsiz

Charles Mendler

2011-03-15T23:59:59.000Z

256

SLUDGE BATCH 7B GLASS VARIABILITY STUDY  

SciTech Connect

The Defense Waste Processing Facility (DWPF) is preparing to initiate processing Sludge Batch 7b (SB7b). In support of the upcoming processing, the Savannah River National Laboratory (SRNL) provided a recommendation to utilize Frits 418 with a 6% Na{sub 2}O addition (26 wt% Na{sub 2}O in sludge) and 702 with a 4% Na{sub 2}O addition (24 wt% Na{sub 2}O in sludge) to process SB7b. This recommendation was based on assessments of the compositional projections for SB7b available at the time from the Savannah River Remediation (SRR). To support qualification of SB7b, SRNL executed a variability study to assess the applicability of the current durability models for SB7b. The durability models were assessed over the expected composition range of SB7b, including potential caustic additions, combined with Frits 702 and 418 over a 32-40% waste loading (WL) range. Thirty four glasses were selected based on Frits 418 and 702 coupled with the sludge projections with an additional 4-6% Na{sub 2}O to reflect the potential caustic addition. Six of these glasses, based on average nominal sludge compositions including the appropriate caustic addition, were developed for both Frit 418 and Frit 702 at 32, 36 and 40% WL to provide coverage in the center of the anticipated SB7b glass region. All glasses were fabricated and characterized using chemical composition analysis, X-ray diffraction (XRD) and the Product Consistency Test (PCT). To comply with the DWPF Glass Product Control Program, a total of thirty four glasses were fabricated to assess the applicability of the current DWPF PCCS durability models. Based on the measured PCT response, all of the glasses were acceptable with respect to the Environmental Assessment (EA) benchmark glass regardless of thermal history. The NL[B] values of the SB7b variability study glasses were less than 1.99 g/L as compared to 16.695 g/L for EA. A small number of the D-optimally selected 'outer layer' extreme vertices (EV) glasses were not predictable using the current Product Composition Control System (PCCS) models for durability, but were acceptable compared to the EA glass when tested. These glasses fell outside of the lower 95% confidence band, which demonstrates conservatism in the model. A few of the glasses fell outside of the upper 95% confidence band; however, these particular glasses have normalized release values that were much lower than the values of EA and should be of no practical concern. Per the requirements of the DWPF Glass Product Control Program, the PCCS durability models have been shown to be applicable to the SB7b sludge system with a range of Na{sub 2}O concentrations blended with Frits 418 or 702. PCT results from the glasses fabricated as part of the variability study were shown to be predictable by the current DWPF PCCS models and/or acceptable with respect to the EA benchmark glass regardless of thermal history or compositional view.

Johnson, F.; Edwards, T.

2011-10-25T23:59:59.000Z

257

Distinct Modes of Internal Variability in the Global Meridional Overturning Circulation Associated with the Southern Hemisphere Westerly Winds  

Science Journals Connector (OSTI)

The internal variability of the global meridional overturning circulation (GMOC) in long-term integration of the earth system model Community Earth System Models (COSMOS) is examined in this study. Two distinct modes of the GMOC, which are closely ...

Wei Wei; Gerrit Lohmann; Mihai Dima

2012-05-01T23:59:59.000Z

258

On the Mechanism of Pacific Multidecadal Climate Variability in CCSM3: The Role of the Subpolar North Pacific Ocean  

Science Journals Connector (OSTI)

Previous analyses of the Community Climate System Model, version 3 (CCSM3) standard integration have revealed pronounced multidecadal variability in the Pacific climate system. The purpose of the present work is to investigate physical mechanism ...

Yafang Zhong; Zhengyu Liu

2009-09-01T23:59:59.000Z

259

A new framework for the simulation of equation-based models with variable structure  

Science Journals Connector (OSTI)

Many modern models contain changes that affect the structure of their underlying equation system, e.g. the breaking of mechanical devices or the switching of ideal diodes. The modeling and simulation of such systems in current equation-based languages ... Keywords: differential-algebraic equations, equation-based modeling, index reduction, variable-structure systems

Dirk Zimmer

2013-08-01T23:59:59.000Z

260

Deutsch-Jozsa algorithm for continuous variables  

E-Print Network (OSTI)

We present an idealized quantum continuous variable analog of the Deutsch-Jozsa algorithm which can be implemented on a perfect continuous variable quantum computer. Using the Fourier transformation and XOR gate appropriate for continuous spectra we show that under ideal operation to infinite precision that there is an infinite reduction in number of query calls in this scheme.

Arun K. Pati; Samuel L. Braunstein

2002-07-18T23:59:59.000Z

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


261

The Galex Ultraviolet Variability (GUVV) Catalog  

E-Print Network (OSTI)

We present Version 1.0 of the NASA Galaxy Evolution Explorer (GALEX) ultraviolet variability catalog (GUVV) that contains information on 84 time-variable and transient sources gained with simultaneous near and far ultraviolet photometric observations. These time-variable sources were serendipitously revealed in the various 1.2 degree star fields currently being surveyed by the GALEX satellite in two ultraviolet bands (NUV 1750-2750A, FUV 1350-1750A) with limiting AB magnitudes of 23-25. The largest-amplitude variable objects presently detected by GALEX are M-dwarf flare stars, which can brighten by 5-10 mag in both the NUV and FUV bands during short duration (< 500s) outbursts. Other types of large-amplitude ultraviolet variable objects include ab-type RR Lyrae stars, which can vary periodically by 2-5mag in the GALEX FUV band. This first GUVV catalog lists galactic positions and possible source identifications in order to provide the astronomical community with a list of time-variable objects that can now be repeatedly observed at other wavelengths. We expect the total number of time-variable source detections to increase as the GALEX mission progresses, such that later version numbers of the GUVV catalog will contain substantially more variable sources.

Barry Y. Welsh; Jonathan M. Wheatley; Kenneth Heafield; Mark Seibert; Stanley E. Browne; Samir Salim; R. Michael Rich; Tom A. Barlow; Luciana Bianchi; Yong-Ik Byun; Jose Donas; Karl Forster; Peter G. Friedman; Timothy M. Heckman; Patrick N. Jelinsky; Young-Wook Lee; Barry F. Madore; Roger F. Malina; D. Christopher Martin; Bruno Milliard; Patrick Morrissey; Susan G. Neff; David Schiminovich; Oswald H. W. Siegmund; Todd Small; Alex S. Szalay; Ted K. Wyder

2005-04-21T23:59:59.000Z

262

Quantum Computing and Hidden Variables Scott Aaronson #  

E-Print Network (OSTI)

Quantum Computing and Hidden Variables Scott Aaronson # Institute for Advanced Study, Princeton of a hidden variable, then we could e#ciently solve problems that are believed to be intractable even powerful than the quantum computing model. PACS numbers: 03.65.Ta, 03.65.Ud, 03.67.Lx, 02.70.­c I

Aaronson, Scott

263

Solar Dynamics Observatory/ Extreme Ultraviolet Variability Experiment  

E-Print Network (OSTI)

Solar Dynamics Observatory/ EVE Extreme Ultraviolet Variability Experiment Frequently Asked and model solar extreme ultraviolet irradiance variations due to solar flares, solar rotation, and solar and structure of the Sun. What is solar variability? Solar radiation varies on all time scales ranging from

Mojzsis, Stephen J.

264

On local-hidden-variable no-go theorems  

E-Print Network (OSTI)

The strongest attack against quantum mechanics came in 1935 in the form of a paper by Einstein, Podolsky and Rosen. It was argued that the theory of quantum mechanics could not be called a complete theory of Nature, for every element of reality is not represented in the formalism as such. The authors then put forth a proposition: we must search for a theory where, upon knowing everything about the system, including possible hidden variables, one could make precise predictions concerning elements of reality. This project was ultimatly doomed in 1964 with the work of Bell Bell, who showed that the most general local hidden variable theory could not reproduce correlations that arise in quantum mechanics. There exist mainly three forms of no-go theorems for local hidden variable theories. Although almost every physicist knows the consequences of these no-go theorems, not every physicist is aware of the distinctions between the three or even their exact definitions. Thus we will discuss here the three principal forms of no-go theorems for local hidden variable theories of Nature. We will define Bell inequalities, Bell inequalities without inequalities and pseudo-telepathy. A discussion of the similarities and differences will follow.

A. A. Methot

2005-11-07T23:59:59.000Z

265

Mass Market Demand Response and Variable Generation Integration Issues: A  

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

Mass Market Demand Response and Variable Generation Integration Issues: A Mass Market Demand Response and Variable Generation Integration Issues: A Scoping Study Title Mass Market Demand Response and Variable Generation Integration Issues: A Scoping Study Publication Type Report Refereed Designation Unknown Year of Publication 2011 Authors Cappers, Peter, Andrew D. Mills, Charles A. Goldman, Ryan H. Wiser, and Joseph H. Eto Pagination 76 Date Published 10/2011 Publisher LBNL City Berkeley Keywords demand response, electricity markets and policy group, energy analysis and environmental impacts department, renewable generation integration, smart grid Abstract The penetration of renewable generation technology (e.g., wind, solar) is expected to dramatically increase in the United States during the coming years as many states are implementing policies to expand this sector through regulation and/or legislation. It is widely understood, though, that large scale deployment of certain renewable energy sources, namely wind and solar, poses system integration challenges because of its variable and often times unpredictable production characteristics (NERC, 2009). Strategies that rely on existing thermal generation resources and improved wind and solar energy production forecasts to manage this variability are currently employed by bulk power system operators, although a host of additional options are envisioned for the near future. Demand response (DR), when properly designed, could be a viable resource for managing many of the system balancing issues associated with integrating large-scale variable generation (VG) resources (NERC, 2009). However, demand-side options would need to compete against strategies already in use or contemplated for the future to integrate larger volumes of wind and solar generation resources. Proponents of smart grid (of which Advanced Metering Infrastructure or AMI is an integral component) assert that the technologies associated with this new investment can facilitate synergies and linkages between demand-side management and bulk power system needs. For example, smart grid proponents assert that system-wide implementation of advanced metering to mass market customers (i.e., residential and small commercial customers) as part of a smart grid deployment enables a significant increase in demand response capability.1 Specifically, the implementation of AMI allows electricity consumption information to be captured, stored and utilized at a highly granular level (e.g., 15-60 minute intervals in most cases) and provides an opportunity for utilities and public policymakers to more fully engage electricity customers in better managing their own usage through time-based rates and near-real time feedback to customers on their usage patterns while also potentially improving the management of the bulk power system. At present, development of time-based rates and demand response programs and the installation of variable generation resources are moving forward largely independent of each other in state and regional regulatory and policy forums and without much regard to the complementary nature of their operational characteristics.2 By 2020, the electric power sector is expected to add ~65 million advanced meters3 (which would reach ~47% of U.S. households) as part of smart grid and AMI4 deployments (IEE, 2010) and add ~40-80 GW of wind and solar capacity (EIA, 2010). Thus, in this scoping study, we focus on a key question posed by policymakers: what role can the smart grid (and its associated enabling technology) play over the next 5-10 years in helping to integrate greater penetration of variable generation resources by providing mass market customers with greater access to demand response opportunities? There is a well-established body of research that examines variable generation integration issues as well as demand response potential, but the nexus between the two has been somewhat neglected by the industry. The studies that have been conducted are informative concerning what could be accomplished with strong broad-based support for the expansion of demand response opportunities, but typically do not discuss the many barriers that stand in the way of reaching this potential. This study examines how demand side resources could be used to integrate wind and solar resources in the bulk power system, identifies barriers that currently limit the use of demand side strategies, and suggests several factors that should be considered in assessing alternative strategies that can be employed to integrate wind and solar resources in the bulk power system. It is difficult to properly gauge the role that DR could play in managing VG integration issues in the near future without acknowledging and understanding the entities and institutions that govern the interactions between variable generation and mass market customers (see Figure ES-1). Retail entities, like load-serving entities (LSE) and aggregators of retail customers (ARC), harness the demand response opportunities of mass market customers through tariffs (and DR programs) that are approved by state regulatory agencies or local governing entities (in the case of public power). The changes in electricity consumption induced by DR as well as the changes in electricity production due to the variable nature of wind and solar generation technologies is jointly managed by bulk power system operators. Bulk power system operators function under tariffs approved by the Federal Energy Regulatory Commission (FERC) and must operate their systems in accordance with rules set by regional reliability councils. These reliability rules are derived from enforceable standards that are set by the North American Electric Reliability Corporation (NERC) and approved by federal regulators. Thus, the role that DR can play in managing VG integration issues is contingent on what opportunities state and local regulators are willing to approve and how customers' response to the DR opportunities can be integrated into the bulk power system both electrically (due to reliability rules) and financially (due to market rules).

266

Integrating Variable Renewable Energy in Electric Power Markets: Best Practices from International Experience (Fact Sheet)  

SciTech Connect

Many countries--reflecting very different geographies, markets, and power systems--are successfully managing high levels of variable renewable energy (RE) on the grid. Australia (South Australia), Denmark, Germany, Ireland, Spain, and the United States (Colorado and Texas), for example, have effectively integrated variable RE utilizing diverse approaches. Analysis of the results from these case studies reveals a wide range of mechanisms that can be used to accommodate high penetrations of variable RE (e.g., from new market designs to centralized planning). Nevertheless, the myriad approaches collectively suggest that governments can best enable variable RE grid integration by implementing best practices in five areas of intervention: lead public engagement, particularly for new transmission; coordinate and integrate planning; develop rules for market evolution that enable system flexibility; expand access to diverse resources and geographic footprint of operations; and improve system operations.

Not Available

2014-10-01T23:59:59.000Z

267

Production-Intent Lost-Motion Variable Valve Actuation Systems...  

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

& Publications Expanding Robust HCCI Operation (Delphi CRADA) Rapid Compression Machine A Key Experimental Device to Effectively Collaborate with Basic Energy Sciences...

268

Efficient Thermally Variable Cooling System | Department of Energy  

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

Directions in Engine-Efficiency and Emissions Research (DEER) Conference in Detroit, MI, September 27-30, 2010. p-07fulton.pdf More Documents & Publications CX-003867:...

269

Anisotropic high temperature superconductors as variable resistors and switches  

SciTech Connect

Several anisotropic high temperature superconductors show critical current densities which are strongly dependent on the direction of an applied external magnetic field. The resistance of a sample can change by several orders of magnitude by applying a magnetic field. The potential for using the field dependent variable resistor or switch for applications in power systems is evaluated. Test results with small samples are presented. The requirements for large scale applications are outlined. The magnetic field triggering requirement, the frequency response of the device, use in 60 Hz ac circuits and heat transfer consideration are investigated. Several application examples are discussed. Use of variable resistor as a fault current limiter, as a switching element in rectifier circuitry and as an improved dump resistor for a superconducting magnet is presented.

Boenig, H.J.; Daugherty, M.A.; Fleshler, S.; Maley, M.P.; Mueller, F.M.; Prenger, F.C.; Coulter, J.Y.

1994-12-01T23:59:59.000Z

270

Hybrid permanent magnet and variable reluctance generator  

SciTech Connect

This patent describes a hybrid electrical generator. It comprises: a permanent magnet generator having a permanent magnet rotor mounted on a shaft, the permanent magnet generator providing an output voltage over an operating range which falls in response to an increasing electrical load; a variable reluctance generator having a rotor mounted on the shaft with excitation of a stator of the variable reluctance generator being provided from the permanent magnet generator, the variable reluctance generator providing an output voltage which varies in response to an increasing electrical load over an operating range; and a voltage regulator, responsive to combined output voltages of the generators, for controlling the output voltage provided by the variable reluctance generator.

Vaidya, J.; Belanger, D.J.

1990-09-25T23:59:59.000Z

271

ENERGY STORAGE SYSTEM REQUIREMENTS FOR SHIPBOARD POWER SYSTEMS SUPPLYING PULSED POWER LOADS.  

E-Print Network (OSTI)

??Energy storage systems will likely be needed for future shipboard power systems that supply loads with high power variability such as pulsed power loads. The… (more)

Duvoor, Prashanth

2008-01-01T23:59:59.000Z

272

Buoyancy-generated variable-density turbulence  

SciTech Connect

Both a one-point (engineering) and a two-point (spectral) model are tested against numerical data. Deficiencies in these variable-density models are disucssed and modifications are suggested. Attention is restricted to turbulent interactions of two miscible, incompressible Newtonian fluids of different densities. Departures from the limits of validity of the Boussinesq approximation are examined. Results of the buoyancy-generated turbulence are compared with variable-density model predictions. 3 figs, 6 refs.

Sandoval, D.L. [Los Alamos National Lab., NM (United States)]|[Washington Univ. (United States); Clark, T.T. [Los Alamos National Lab., NM (United States); Riley, J.J. [Washington Univ. (United States)

1996-06-01T23:59:59.000Z

273

Prctica 2. Anlisi descriptiva univariable: variables qualitatives  

E-Print Network (OSTI)

nominal SEXO. Codificada de tipus "numèrica" amb valors 1 i 2. Aquests valors s'etiqueten amb: 1 `Hombre": (1) Seleccionem la variable sexo i la col·loquem al requadre de "Variables". D'aquesta manera obtenim: Frecuencias [Conjunto_de_datos1] C:\\Archivos de programa\\SPSS\\GSS93 reducido.sav Estadísticos sexo Sexo del

Castellana, NatĂ lia

274

Prctica 2. Anlisi descriptiva univariable: variables qualitatives  

E-Print Network (OSTI)

nominal SEXO. Codificada de tipus "numèrica" amb valors 1 i 2. Aquests valors s'etiqueten amb: 1 `Hombre) Seleccionem la variable sexo i la col·loquem al requadre de "Variables". D'aquesta manera obtenim la taula de Estadísticos Sexo del entrevistado 1500 0 2 Válidos Perdidos N Moda sexo Sexo del entrevistado 641 42,7 42,7 42

Castellana, NatĂ lia

275

Suppression of chaos at slow variables by rapidly mixing fast dynamics through linear energy-preserving coupling  

E-Print Network (OSTI)

Chaotic multiscale dynamical systems are common in many areas of science, one of the examples being the interaction of the low-frequency dynamics in the atmosphere with the fast turbulent weather dynamics. One of the key questions about chaotic multiscale systems is how the fast dynamics affects chaos at the slow variables, and, therefore, impacts uncertainty and predictability of the slow dynamics. Here we demonstrate that the linear slow-fast coupling with the total energy conservation property promotes the suppression of chaos at the slow variables through the rapid mixing at the fast variables, both theoretically and through numerical simulations. A suitable mathematical framework is developed, connecting the slow dynamics on the tangent subspaces to the infinite-time linear response of the mean state to a constant external forcing at the fast variables. Additionally, it is shown that the uncoupled dynamics for the slow variables may remain chaotic while the complete multiscale system loses chaos and becomes completely predictable at the slow variables through increasing chaos and turbulence at the fast variables. This result contradicts the common sense intuition, where, naturally, one would think that coupling a slow weakly chaotic system with another much faster and much stronger mixing system would result in general increase of chaos at the slow variables.

Rafail V. Abramov

2011-05-16T23:59:59.000Z

276

May 2013 PSERC Webinar: Managing Wind Variability with Self-Reserves and  

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

May 2013 PSERC Webinar: Managing Wind Variability with May 2013 PSERC Webinar: Managing Wind Variability with Self-Reserves and Responsive Demand May 2013 PSERC Webinar: Managing Wind Variability with Self-Reserves and Responsive Demand April 9, 2013 - 10:40am Addthis The DOE-funded Power Systems Engineering Research Center (PSERC) is offering a free public webinar on managing wind variability in energy production. The webinar will be held Tuesday, May 7, 2013 from 2-3 p.m. No pre-registration is necessary. Using wind power to supply up to 20%, or more, of electrical demand is increasingly popular in policy mandates, yet is relatively untested in terms of actual system and market operations. This presentation will investigate the concept of self-reserves, wherein wind generators withhold a portion of forecasted energy production, via their hour-ahead schedule,

277

U-090: RSA enVision Discloses Environment Variable Information to Remote  

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

0: RSA enVision Discloses Environment Variable Information to 0: RSA enVision Discloses Environment Variable Information to Remote Users U-090: RSA enVision Discloses Environment Variable Information to Remote Users January 27, 2012 - 6:00am Addthis PROBLEM: A vulnerability was reported in RSA enVision PLATFORM: Version(s): 4.0 prior to 4.0 SP4 P5, 4.1 prior to 4.1 P3 ABSTRACT: A remote user can view potentially sensitive data on the target system. reference LINKS: CVE-2011-4143 SecurityTracker Alert ID: 1026591 Secunia Advisory IMPACT ASSESSMENT: Medium Discussion: The security issue is caused due to the application disclosing certain environment variables containing web system setup information via the web interface. Further information about this resolution and other fixes can be found in the Release Notes associated with RSA enVision 4.1, Patch 3 and

278

The dynamics of variable-density turbulence  

SciTech Connect

The dynamics of variable-density turbulent fluids are studied by direct numerical simulation. The flow is incompressible so that acoustic waves are decoupled from the problem, and implying that density is not a thermodynamic variable. Changes in density occur due to molecular mixing. The velocity field, is in general, divergent. A pseudo-spectral numerical technique is used to solve the equations of motion. Three-dimensional simulations are performed using a grid size of 128{sup 3} grid points. Two types of problems are studied: (1) the decay of isotropic, variable-density turbulence, and (2) buoyancy-generated turbulence in a fluid with large density fluctuations. In the case of isotropic, variable-density turbulence, the overall statistical decay behavior, for the cases studied, is relatively unaffected by the presence of density variations when the initial density and velocity fields are statistically independent. The results for this case are in quantitative agreement with previous numerical and laboratory results. In this case, the initial density field has a bimodal probability density function (pdf) which evolves in time towards a Gaussian distribution. The pdf of the density field is symmetric about its mean value throughout its evolution. If the initial velocity and density fields are statistically dependent, however, the decay process is significantly affected by the density fluctuations. For the case of buoyancy-generated turbulence, variable-density departures from the Boussinesq approximation are studied. The results of the buoyancy-generated turbulence are compared with variable-density model predictions. Both a one-point (engineering) model and a two-point (spectral) model are tested against the numerical data. Some deficiencies in these variable-density models are discussed and modifications are suggested.

Sandoval, D.L.

1995-11-01T23:59:59.000Z

279

Cloud speed impact on solar variability scaling â?? Application to the wavelet variability model  

E-Print Network (OSTI)

Kleissl, J. , 2013. Deriving cloud velocity from an array ofCloud Speed Impact on Solar Variability Scaling -this work, we determine from cloud speeds. Cloud simulator

Lave, Matthew; Kleissl, Jan

2013-01-01T23:59:59.000Z

280

Variable rate spreader for real-time spot-application of granular fertilizer in wild blueberry  

Science Journals Connector (OSTI)

The commercial variable rate (VR) fertilizer spreader can change fertilizer rates in different management zones using global positioning system (GPS) guided prescription maps. The VR fertilizer spreader allows the independent control only on half of ... Keywords: Controller, Digital photography, Fertilizer, Sensing and control system, Spot-application, Wild blueberry

Hassan S. Chattha; Qamar U. Zaman; Young K. Chang; Scott Read; Arnold W. Schumann; Gordon R. Brewster; Aitazaz A. Farooque

2014-01-01T23:59:59.000Z

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


281

On the practice of dichotomization of quantitative variables  

E-Print Network (OSTI)

The authors examine the practice of dichotomization of quantitative measures, wherein relationships among variables are examined after 1 or more variables have been converted to dichotomous variables by splitting the sample ...

MacCallum, R. C.; Zhang, S.; Preacher, K. J.; Rucker, D. D.

2002-01-01T23:59:59.000Z

282

Software Enabled Virtually Variable Displacement Pumps -Theoretical and Experimental Studies  

E-Print Network (OSTI)

Software Enabled Virtually Variable Displacement Pumps - Theoretical and Experimental Studies the functional equivalent of a variable displacement pump. This approach combines a fixed displacement pump valve control, without many of the shortcomings of commercially available variable displacement pumps

Li, Perry Y.

283

The use of 'race' as a variable in biomedical research  

E-Print Network (OSTI)

be used as a variable in biomedical research but mainly toRace’ as a Variable in Biomedical Research A dissertationRace’ as a Variable in Biomedical Research…………. Manifest,

Efstathiou, Sophia

2009-01-01T23:59:59.000Z

284

Lateral Control of Heavy Vehicles for Automated Systems  

E-Print Network (OSTI)

system tracks the desired front wheel steering angle (? 1 ) exactly, then the sliding variable will asymptotically converg to a ball,

Hingwe, Pushkar; Wang, Jen-Yu; Tai, Meihua; Tomizuka, Masayoshi

2003-01-01T23:59:59.000Z

285

Preventing Quantum Hacking in Continuous Variable Quantum Key Distribution  

Science Journals Connector (OSTI)

Security loopholes have been shown for discrete-variable Quantum Key Distribution (QKD). Here, we propose and provide experimental evidence of an attack targeting a continuous-variable...

Jouguet, Paul; Diamanti, Eleni; Kunz-Jacques, Sébastien

286

Impact of Real Field Diesel Quality Variability on Engine Emissions...  

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

Real Field Diesel Quality Variability on Engine Emissions and Fuel Consumption Solutions for Onboard Optimisation Impact of Real Field Diesel Quality Variability on Engine...

287

Adaptation to Climate Variability and Change: A Guidance Manual...  

Open Energy Info (EERE)

to Climate Variability and Change: A Guidance Manual for Development Planning Jump to: navigation, search Tool Summary LAUNCH TOOL Name: Adaptation to Climate Variability and...

288

Microstructural Response of Variably Hydrated Ca-Rich Montmorillonite...  

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

Microstructural Response of Variably Hydrated Ca-Rich Montmorillonite to Supercritical CO2. Microstructural Response of Variably Hydrated Ca-Rich Montmorillonite to Supercritical...

289

Pitch-variable blazed grating consisting of freestanding silicon beams  

Science Journals Connector (OSTI)

Theoretical analysis is presented for a pitch-variable blazed grating which consists of freestanding silicon beams. The pitch-variable blazed grating is implemented by combining...

Wang, Yongjin; Kanamori, Yoshiaki; Hane, Kazuhiro

2009-01-01T23:59:59.000Z

290

Advanced Variable Speed Air-Source Integrated Heat Pump 2013...  

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

Advanced Variable Speed Air-Source Integrated Heat Pump 2013 Peer Review Advanced Variable Speed Air-Source Integrated Heat Pump 2013 Peer Review Emerging Technologies Project for...

291

Nonmonotone line search methods with variable sample size  

E-Print Network (OSTI)

The nonmonotone line search framework is embedded with a variable sample size ... the line search combines well with the variable sample size scheme as.

2014-02-17T23:59:59.000Z

292

Solutions for Interharmonics in Variable Speed Drives for LNG Plants:.  

E-Print Network (OSTI)

??Variable speed drives can cause components of any frequency known as interharmonics. Large variable speed drives in the order of tens of megawatts can replace… (more)

Verhulst, M.P.A.

2011-01-01T23:59:59.000Z

293

INSTALLATION, COMMISSIONING AND TROUBLE SHOOTING OF VARIABLE FREQUENCY DRIVE.  

E-Print Network (OSTI)

??In this thesis, the installation of variable frequency drive on board a ship is introduced briefly. In this particular study the variable frequency drive was… (more)

Kuituniemi, Santtu

2013-01-01T23:59:59.000Z

294

Control Strategies for Centrifugal Pumps with Variable Flow Rate...  

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

Control Strategies for Centrifugal Pumps with Variable Flow Rate Requirements Control Strategies for Centrifugal Pumps with Variable Flow Rate Requirements This tip sheet discusses...

295

Variable Renewable Energy: a Regulatory Roadmap (Fact Sheet)...  

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

Variable Renewable Energy: a Regulatory Roadmap Research Highlights There is not a one-size-fits-all approach to the regulation of variable renewable energy (VRE), but...

296

Estimating climatological variability of solar energy production  

Science Journals Connector (OSTI)

Abstract A method is presented for estimating the climatological variability of yearly and monthly photovoltaic power production per 1 kWp of installed power. This quantity is computed for a specified portfolio of sources on the basis of historical data. Its climatological variability is derived from a simulation of 33 years of power production with hourly time step. Underlying meteorological variables are taken from the MERRA reanalysis for the years 1979–2011. Since the MERRA reanalysis is not a traditional data source for photovoltaic power modelling, various comparisons to available and more frequently used data sources are included. The method of estimation has the advantage of wide applicability due to the global coverage of the meteorological data.

Pavel Juruš; Kryštof Eben; Jaroslav Resler; Pavel Kr?; Ivan Kasanický; Emil Pelikán; Marek Brabec; Ji?í Hošek

2013-01-01T23:59:59.000Z

297

Thermodynamics of Inhomogeneous Systems  

Science Journals Connector (OSTI)

A self-consistent thermodynamic formalism is developed for the treatment of the equilibrium of systems, some of whose parameters vary continuously from place to place. The method is specially designed for the description of transition interfaces separating two phases. The energy per unit volume is assumed to depend explicitly on the space derivatives of the molecule densities. Equilibrium conditions are obtained for the appropriate internal variables of the system, and all externally measurable intensive variables are uniquely defined by a variational procedure.

Edward W. Hart

1959-01-15T23:59:59.000Z

298

The Kelastic variable wall mining machine. Interim final report  

SciTech Connect

This machine cuts coal along a longwall face extending up to 500 feet by a rotating auger with bits. The machine also transports the coal that is cut acting as screw conveyor. By virtue of an integral shroud comprising part of the conveyor the machine is also amenable to a separation of the zones where men work from air being contaminated by dust and methane gas by the cutting action. Beginning as single intake air courses, the air separates at the working section where one split provides fresh air to the Occupied Zone (OZ) for human needs and the other split purges and carries away dust and methane from face fragmentation in the Cutting Zone (CZ). The attractiveness of the Variable Wall Mining Machine is that it addresses the limitations of current longwall mining equipment: it can consistently out-produce continuous mining machines and most longwall shearing machines. It also is amenable to configuring an environment, the dual-duct system, where the air for human breathing is separated from dust-laden ventilating air with methane mixtures. The objective of the research was to perform a mathematical and experimental study of the interrelationships of the components of the system so that a computer model could demonstrate the workings of the system in an animation program. The analysis resulted in the compilation of the parameters for three different configurations of a dual aircourse system of ventilating underground mines. In addressing the goal of an inherently safe mining system the dual-duct adaptation to the Variable Wall Mining Machine appears to offer the path to solution. The respirable dust problem is solvable; the explosive dust problem is nearly solvable; and the explosive methane problem can be greatly reduced. If installed in a highly gassy mine, the dual duct models would also be considerably less costly.

NONE

1995-11-12T23:59:59.000Z

299

The Deep Lens Survey Transient Search. I. Short Timescale and Astrometric Variability  

Science Journals Connector (OSTI)

We report on the methodology and first results from the Deep Lens Survey (DLS) transient search. We utilize image subtraction on survey data to yield all sources of optical variability down to 24th magnitude. Images are analyzed immediately after acquisition, at the telescope, and in near-real time, to allow for follow-up in the case of time-critical events. All classes of transients are posted to the World Wide Web upon detection. Our observing strategy allows sensitivity to variability over several decades in timescale. The DLS is the first survey to classify and report all types of photometric and astrometric variability detected, including solar system objects, variable stars, supernovae, and short timescale phenomena. Three unusual optical transient (OT) events were detected, flaring on 1000 s timescales. All three events were seen in the B passband, suggesting blue color indices for the phenomena. One event (OT 20020115) is determined to be from a flaring Galactic dwarf star of spectral type dM4. From the remaining two events, we find an overall rate of ? = 1.4 events deg-2 day-1 on 1000 s timescales, with a 95% confidence limit of ? R passband yields an upper 95% confidence limit on short-timescale astronomical variability in the range 19.5 R R -2 day-1. We report also on our ensemble of astrometrically variable objects, as well as an example of photometric variability with an undetected precursor.

A. C. Becker; D. M. Wittman; P. C. Boeshaar; A. Clocchiatti; I. P. Dell'Antonio; D. A. Frail; J. Halpern; V. E. Margoniner; D. Norman; J. A. Tyson; R. A. Schommer

2004-01-01T23:59:59.000Z

300

An Exploratory Study of Variability in Safety  

E-Print Network (OSTI)

An Exploratory Study of Variability in Safety Culture among Clinician types and Patient Care of the current study was to (a) examine how different types of care providers viewed the safety culture of their unit, and (b) examine the relationship between hospital safety culture and patient satisfaction

von der Heydt, RĂĽdiger

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


301

SYNTHESIS: MODELING VARIABILITY AND CONSTRAINTS Rolf Carlson  

E-Print Network (OSTI)

SYNTHESIS: MODELING VARIABILITY AND CONSTRAINTS Rolf Carlson This is a modified version. Abstract This paper discusses some important topics in current speech synthesis research. Modeling of speaker characteristics and emotions are used as a examples of new trends in the speech synthesis field

Carlson, Rolf

302

Galactic Variable Sky with EGRET and GLAST  

SciTech Connect

The characteristics of the largely-unidentified Galactic sources of gamma rays that were detected by EGRET are reviewed. Proposed source populations that may have the correct spatial, spectral, luminosity, and variability properties to be the origins of the EGRET sources are also presented. Finally, the prospects for studying Galactic gamma-ray sources with the GLAST LAT are reviewed.

Digel, S.W.; /SLAC

2006-11-28T23:59:59.000Z

303

TimeVariable Photo-Evaporation of  

E-Print Network (OSTI)

TimeVariable Photo-Evaporation of Protoplanetary Disks Henry Throop (SwRI) John Bally (U. Colorado) #12;Takeaway: Photo-evaporation alters the disk structure in essentially unpredictable ways, because for disks formed at the same time in the same cluster. #12;30 Doradus: 100+ O/B stars Photo

Throop, Henry

304

Heart Rate Variability Malvin Carl Teich  

E-Print Network (OSTI)

Heart Rate Variability Malvin Carl Teich Boston University and Columbia University http, Grasmere, UK, 2005 #12;CONGESTIVE HEART FAILURE INABILITY OF HEART TO INCREASE CARDIAC OUTPUT IN PROPORTION of breath Swelling in legs General fatigue and weakness Clinical diagnostics: Ascultate heart Carotid pulse

Teich, Malvin C.

305

The QSO variability-luminosity-redshift relation  

Science Journals Connector (OSTI)

......to test Poissonian (or 'Christmas-tree') models for QSO variability...mean B-band luminosity in the light curve and a(LB) is its standard...comparison of the UV and optical light curves of NGC 4151 and 5548...spanning 16 yr. The rest-frame light curves are between 3.2 and......

Roberto Cid Fernandes; Jr; Itziar Aretxaga; Roberto Terlevich

1996-10-11T23:59:59.000Z

306

The Sun is an active, variable,  

E-Print Network (OSTI)

The Sun is an active, variable, magnetic star with oscillations on its surface and deep within its the physical processes of the Sun-Earth connection. Visit Us on the Web: Solar Terrestrial Probes Program: http://stp.gsfc.nasa.gov For More Information, See: Sun-Earth Connection: http://sec.gsfc.nasa.gov Living With a Star: http

Christian, Eric

307

Chapter 18: Variable Frequency Drive Evaluation Protocol  

SciTech Connect

An adjustable-speed drive (ASD) includes all devices that vary the speed of a rotating load, including those that vary the motor speed and linkage devices that allow constant motor speed while varying the load speed. The Variable Frequency Drive Evaluation Protocol presented here addresses evaluation issues for variable-frequency drives (VFDs) installed on commercial and industrial motor-driven centrifugal fans and pumps for which torque varies with speed. Constant torque load applications, such as those for positive displacement pumps, are not covered by this protocol. Other ASD devices, such as magnetic drive, eddy current drives, variable belt sheave drives, or direct current motor variable voltage drives, are also not addressed. The VFD is by far the most common type of ASD hardware. With VFD speed control on a centrifugal fan or pump motor, energy use follows the affinity laws, which state that the motor electricity demand is a cubic relationship to speed under ideal conditions. Therefore, if the motor runs at 75% speed, the motor demand will ideally be reduced to 42% of full load power; however, with other losses it is about 49% of full load power.

Romberger, J.

2014-11-01T23:59:59.000Z

308

Variable Light-Cone Theory of Gravity  

E-Print Network (OSTI)

We show how to reformulate Variable Speed of Light Theories (VSLT) in a covariant fashion as Variable Light-Cone Theories (VLCT) by introducing two vierbein bundles each associated with a distinct metric. The basic gravitational action relates to one bundle while matter propagates relative to the other in a conventional way. The variability of the speed of light is represented by the variability of the matter light-cone relative to the gravitational light-cone. The two bundles are related locally by an element M, of SL(4,R). The dynamics of the field M is that of a SL(4,R)-sigma model gauged with respect to local (orthochronous) Lorentz transformations on each of the bundles. Only the ``massless'' version of the model with a single new coupling, F, that has the same dimensions as Newton's constant $G_N$, is considered in this paper. When F vanishes the theory reduces to standard General Relativity. We verify that the modified Bianchi identities of the model are consistent with the standard conservation law for the matter energy-momentum tensor in its own background metric. The implications of the model for some simple applications are examined, the Newtonian limit, the flat FRW universe and the spherically symmetric static solution.

I. T. Drummond

1999-08-20T23:59:59.000Z

309

IEEE JOURNAL OF SOLID-STATE CIRCUITS, VOL. 43, NO. 4, APRIL 2008 881 Exploring Variability and Performance  

E-Print Network (OSTI)

IEEE JOURNAL OF SOLID-STATE CIRCUITS, VOL. 43, NO. 4, APRIL 2008 881 Exploring Variability consumption of these systems ultimately limits form factor, battery life, and complexity. It is therefore

Austin, Todd M.

310

Modeling variable density effects in turbulent flames -- Some basic considerations  

SciTech Connect

The paper discusses the basic physical phenomena involved in pressure-density interactions, and presents models of pressure-velocity, pressure-scalar, baroclinic and dilatation effects for variable density low Mach-number turbulence. Their implementation in the {kappa}-{epsilon} framework is then described and their performance evaluated. The models assume that both scalar transport and turbulence generation arising from pressure-density interactions in flames are caused by the motion of large scale turbulent thermals superposed on the normal turbulence mechanism. The velocity of the thermals is related directly to the mean pressure gradient and local density differences in the flames. It is furthermore assumed that the correction for dilatation effects in the {kappa}-{epsilon} system can be determined from the constraint of conservation of the angular momentum of turbulence per unit mass. Simple corrections of the {kappa}-{epsilon} system are proposed for fast chemistry diffusion and premixed flames subject to variable pressure gradients, which offer substantial improvements in the predictions of the flames. some problems remain, particularly in predictions of turbulence in premixed flames, owing to large scale instabilities of the flames observed in the experiments.

Chomiak, J.; Nisbet, J.R. [Chalmers Univ. of Technology, Goeteborg (Sweden). Dept. of Thermo and Fluid Dynamics] [Chalmers Univ. of Technology, Goeteborg (Sweden). Dept. of Thermo and Fluid Dynamics

1995-08-01T23:59:59.000Z

311

Modeling of ECM Controlled Series Fan-powered VAV Terminal Units  

E-Print Network (OSTI)

Semi-empirical models for series fan-powered variable air volume terminal units (FPTUs) were developed based on models of the primary, plenum, fan airflow and the fan power consumption. The experimental setups and test procedures were developed...

Yin, Peng

2011-10-21T23:59:59.000Z

312

Energy Efficiency Improvement and Cost Saving Opportunities for the Pharmaceutical Industry. An ENERGY STAR Guide for Energy and Plant Managers  

E-Print Network (OSTI)

for its cooling tower water. Solar air heating. Solar airSolar air heating Building insulation Restriction of sash openings Variable-air-volume hoods Improved filtration quality and efficiency Cooling towers

Galitsky, Christina

2008-01-01T23:59:59.000Z

313

Correlated spectral variability in brown dwarfs  

E-Print Network (OSTI)

Models of brown dwarf atmospheres suggest they exhibit complex physical behaviour. Observations have shown that they are indeed dynamic, displaying small photometric variations over timescales of hours. Here I report results of infrared (0.95-1.64 micron) spectrophotometric monitoring of four field L and T dwarfs spanning timescales of 0.1-5.5 hrs, the goal being to learn more about the physical nature of this variability. Spectra are analysed differentially with respect to a simultaneously observed reference source in order to remove Earth-atmospheric variations. The variability amplitude detected is typically 2-10%, depending on the source and wavelength. I analyse the data for correlated variations between spectral indices. This approach is more robust than single band or chisq analyses, because it does not assume an amplitude for the (often uncertain) noise level (although the significance test still assumes a shape for the noise power spectrum). Three of the four targets show significant evidence for correlated variability. Some of this can be associated with specific features including Fe, FeH, VO and KI, and there is good evidence for intrinsic variability in water and possibly also methan. Yet some of this variability covers a broader spectral range which would be consistent with dust opacity variations. The underlying common cause is plausibly localized temperature or composition fluctuations caused by convection. Looking at the high signal-to-noise ratio stacked spectra we see many previously identified spectral features of L and T dwarfs, such as KI, NaI, FeH, water and methane. In particular we may have detected methane absorption at 1.3-1.4 micron in the L5 dwarf SDSS 0539-0059.

C. A. L. Bailer-Jones

2007-11-28T23:59:59.000Z

314

Costs of Solar and Wind Power Variability for Reducing CO2 Emissions  

Science Journals Connector (OSTI)

Our research differs from earlier solar PV studies because we use real power output data from operational utility-scale plants to calculate the variability and cost of variability. ... In addition, the ISO utilizes up and down regulation equivalent to the minimum and maximum deviation from qh, respectively (lower right graph). ... (9) The Docket states that ISOs may use the same rate they charge utilities for load variability in Schedule 3. FERC envisions that individual transmission utilities can apply to charge different rates as long as they “demonstrate that the per-unit cost of regulation reserve capacity is somehow different when such capacity is utilized to address system variability associated with generator resources”. ...

Colleen Lueken; Gilbert E. Cohen; Jay Apt

2012-08-09T23:59:59.000Z

315

Diagnosis of Effectiveness of HVAC System and Energy Performance of Osaka-Gas Building through Retro-Commissioning Part 1 Outline of HVAC Systems and Diagnosis of Energy Efficiency of Air Systems  

E-Print Network (OSTI)

-22b AC-22a AC-22b INV Output 97% (58.2Hz) 84% (50.4Hz) 70% (40.8Hz) Air volume at the outlet duct 87,848 m3/h 56,968 m3/h 42,635 m3/h Power consumption 70.0kW 46.8kW 20.6kW Outlet static pressure 854Pa 798Pa 802Pa 5F MD... 2013 Note 1: Circles (?) in Figure 6.1 represent operating points of the fans alone. Triangles (?) represent operating air volumes calculated based on the fan’s static pressure. Note 2: Numbers in boxes ??? represent air volume measurement...

Hatanaka,T.; Aoki,K; Matsuda, N.; Yamaha,M.; Tanaka,H.; Nakahara,N.

2014-01-01T23:59:59.000Z

316

IEEE TRANSACTIONS ON ENERGY CONVERSION, VOL. 23, NO. 2, JUNE 2008 551 Sliding Mode Power Control of Variable-Speed Wind  

E-Print Network (OSTI)

IEEE TRANSACTIONS ON ENERGY CONVERSION, VOL. 23, NO. 2, JUNE 2008 551 Sliding Mode Power Control of Variable-Speed Wind Energy Conversion Systems Brice Beltran, Tarek Ahmed-Ali, and Mohamed El Hachemi in variable-speed wind energy conversion sys- tems (VS-WECS). These systems have two operation regions de

Paris-Sud XI, Université de

317

Hyperthermic Peritoneal Perfusion System in Canines  

Science Journals Connector (OSTI)

...outlet tubing for aseptic operation. The filter system has a combined surface...variability of the biological system becomes the final determinant...evaluation of the TIFS operation has concentrated upon...control shut-down system, the relationship of...

John S. Spratt; Robert A. Adcock; William Sherrill; and S. Travathen

1980-02-01T23:59:59.000Z

318

Energy Systems Integration  

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

Systems Integration Systems Integration Ben Kroposki, PhD, PE Director, Energy Systems Integration National Renewable Energy Laboratory 2 Reducing investment risk and optimizing systems in a rapidly changing energy world * Increasing penetration of variable RE in grid * Increasing ultra high energy efficiency buildings and controllable loads * New data, information, communications and controls * Electrification of transportation and alternative fuels * Integrating energy storage (stationary and mobile) and thermal storage * Interactions between electricity/thermal/fuels/data pathways * Increasing system flexibility and intelligence Current Energy Systems Future Energy Systems Why Energy Systems Integration? 3 Energy Systems Integration Continuum Scale Appliance (Plug)

319

IEEE TRANSACTIONS ON POWER ELECTRONICS, VOL. 12, NO. 1, JANUARY 1997 87 Fuzzy Logic Based Intelligent Control of a Variable  

E-Print Network (OSTI)

system. The generation system has fuzzy logic control with vector control in the inner loops. A fuzzyIEEE TRANSACTIONS ON POWER ELECTRONICS, VOL. 12, NO. 1, JANUARY 1997 87 Fuzzy Logic Based a variable speed wind genera- tion system where fuzzy logic principles are used for efficiency optimization

Simões, Marcelo Godoy

320

The VISTA Variables in the Via Lactea survey: A first glance on stellar variability  

E-Print Network (OSTI)

VISTA Variables in the Via Lactea (VVV) is an ESO public near-infrared variability survey of the Galactic bulge and an adjacent area of the southern mid-plane. It will produce a deep atlas in the ZYJHKs filters, and a Ks-band time-series database of ~10^9 point sources, among which >~10^6 are expected to be variable. One of VVV's immediate scientific goals is to provide accurate light curves of primary distance indicators, such as RR Lyrae stars, and utilize these data to produce a 3-D map of the surveyed area and, ultimately, trace the structure of the inner Galaxy. We give, based on the first ~1.5 years of the 5-yr-long survey, an early assessment on the basic properties and the overall quality of the VVV photometric time-series, and use these data to put an estimate of the fraction of variable stellar sources.

Dekany, I; Minniti, D

2011-01-01T23:59:59.000Z

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


321

Variables Affecting Economic Development of Wind Energy  

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

Variables Affecting Economic Variables Affecting Economic Development of Wind Energy E. Lantz and S. Tegen National Renewable Energy Laboratory Presented at WINDPOWER 2008 Houston, Texas June 1-4, 2008 Conference Paper NREL/CP-500-43506 July 2008 NREL is operated by Midwest Research Institute â—Ź Battelle Contract No. DE-AC36-99-GO10337 NOTICE The submitted manuscript has been offered by an employee of the Midwest Research Institute (MRI), a contractor of the US Government under Contract No. DE-AC36-99GO10337. Accordingly, the US Government and MRI retain a nonexclusive royalty-free license to publish or reproduce the published form of this contribution, or allow others to do so, for US Government purposes. This report was prepared as an account of work sponsored by an agency of the United States government.

322

Thermodynamics in variable speed of light theories  

SciTech Connect

The perfect fluid in the context of a covariant variable speed of light theory proposed by J. Magueijo is studied. On the one hand the modified first law of thermodynamics together with a recipe to obtain equations of state are obtained. On the other hand the Newtonian limit is performed to obtain the nonrelativistic hydrostatic equilibrium equation for the theory. The results obtained are used to determine the time variation of the radius of Mercury induced by the variability of the speed of light (c), and the scalar contribution to the luminosity of white dwarfs. Using a bound for the change of that radius and combining it with an upper limit for the variation of the fine structure constant, a bound on the time variation of c is set. An independent bound is obtained from luminosity estimates for Stein 2015B.

Racker, Juan [CONICET, Centro Atomico Bariloche, Avenida Bustillo 9500 (8400), San Carlos De Bariloche (Argentina); Facultad de Ciencias Astronomicas y Geofisicas, Universidad Nacional de La Plata, Paseo del Bosque S/N (1900), La Plata (Argentina); Sisterna, Pablo [Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Mar del Plata, Funes 3350 (7600), Mar del Plata (Argentina); Vucetich, Hector [Facultad de Ciencias Astronomicas y Geofisicas, Universidad Nacional de La Plata, Paseo del Bosque S/N (1900), La Plata (Argentina)

2009-10-15T23:59:59.000Z

323

Correlated spectral variability in brown dwarfs  

E-Print Network (OSTI)

Models of brown dwarf atmospheres suggest they exhibit complex physical behaviour. Observations have shown that they are indeed dynamic, displaying small photometric variations over timescales of hours. Here I report results of infrared (0.95-1.64 micron) spectrophotometric monitoring of four field L and T dwarfs spanning timescales of 0.1-5.5 hrs, the goal being to learn more about the physical nature of this variability. Spectra are analysed differentially with respect to a simultaneously observed reference source in order to remove Earth-atmospheric variations. The variability amplitude detected is typically 2-10%, depending on the source and wavelength. I analyse the data for correlated variations between spectral indices. This approach is more robust than single band or chisq analyses, because it does not assume an amplitude for the (often uncertain) noise level (although the significance test still assumes a shape for the noise power spectrum). Three of the four targets show significant evidence for cor...

Bailer-Jones, C A L

2007-01-01T23:59:59.000Z

324

X-ray variability in M87  

E-Print Network (OSTI)

We present the evidence for X-ray variability from the core and from knot A in the M87 jet based on data from two observations with the Einstein Observatory High Resolution Imager (HRI) and three observations with the ROSAT HRI. The core intensity showed a 16% increase in 17 months ('79-'80); a 12% increase in the 3 years '92 to '95; and a 17% drop in the last half of 1995. The intensity of knot A appears to have decreased by 16% between 92Jun and 95Dec. Although the core variability is consistent with general expectations for AGN nuclei, the changes in knot A provide constraints on the x-ray emission process and geometry. Thus we predict that the x-ray morphology of knot A will differ significantly from the radio and optical structure.

D. E. Harris; J. A. Biretta; W. Junor

1996-12-05T23:59:59.000Z

325

Variable aperture collimator for high energy radiation  

DOE Patents (OSTI)

An apparatus is disclosed providing a variable aperture energy beam collimator. A plurality of beam opaque blocks are in sliding interface edge contact to form a variable aperture. The blocks may be offset at the apex angle to provide a non-equilateral aperture. A plurality of collimator block assemblies may be employed for providing a channel defining a collimated beam. Adjacent assemblies are inverted front-to-back with respect to one another for preventing noncollimated energy from emerging from the apparatus. An adjustment mechanism comprises a cable attached to at least one block and a hand wheel mechanism for operating the cable. The blocks are supported by guide rods engaging slide brackets on the blocks. The guide rods are pivotally connected at each end to intermediate actuators supported on rotatable shafts to change the shape of the aperture. A divergent collimated beam may be obtained by adjusting the apertures of adjacent stages to be unequal.

Hill, Ronald A. (Albuquerque, NM)

1984-05-22T23:59:59.000Z

326

Thermodynamics in variable speed of light theories  

E-Print Network (OSTI)

The perfect fluid in the context of a covariant variable speed of light theory proposed by J. Magueijo is studied. On the one hand the modified first law of thermodynamics together with a recipe to obtain equations of state are obtained. On the other hand the Newtonian limit is performed to obtain the nonrelativistic hydrostatic equilibrium equation for the theory. The results obtained are used to determine the time variation of the radius of Mercury induced by the variability of the speed of light ($c$), and the scalar contribution to the luminosity of white dwarfs. Using a bound for the change of that radius and combining it with an upper limit for the variation of the fine structure constant, a bound on the time variation of $c$ is set. An independent bound is obtained from luminosity estimates for Stein 2015B.

Juan Racker; Pablo Sisterna; Hector Vucetich

2007-11-06T23:59:59.000Z

327

Teleportation-Based Continuous Variable Quantum Cryptography  

E-Print Network (OSTI)

We show a continuous variable (CV) quantum key distribution (QKD) scheme based on the CV quantum teleportation of coherent states that yields a raw secret key made up of discrete variables for both Alice and Bob. This protocol preserves the efficient detection schemes of current CV technology (no single-photon detection techniques) and, at the same time, has efficient error correction and privacy amplification schemes due to its binary discrete key. In particular, it is secure for any value of the transmission efficiency of the optical line used by Alice to share entangled two-mode squeezed states with Bob (no 3 dB or 50% loss limitation characteristic of beam splitting attacks). The present CVQKD protocol works deterministically (no postselection needed) with efficient direct reconciliation techniques (no reverse reconciliation) in order to generate a secure key, even at the surprisingly 100% loss case.

F. S. Luiz; Gustavo Rigolin

2014-08-21T23:59:59.000Z

328

Buoyancy-generated variable-density turbulence  

SciTech Connect

Because of the importance of turbulence mixing in many applications, a number of turbulence mixing models have been proposed for variable- density flows. These engineering models (one- point statistical models) typically include the transport of the turbulent kinetic energy and the turbulent energy dissipation rate (i.e., k - {epsilon} models). The model presented by Besnard, Harlow, Rauenzahn and Zemach (1992) (herein referred to as BHRZ) is a one-point model intended to describe variable-density turbulent flows. Transport equations for the Reynolds stress tensor, R{sub ij}, and the turbulent energy dissipation rate, the density-velocity correlation, a{sub i}, and the density-specific volume correlation, b are derived. This model employs- techniques and concepts from incompressible, constant- density turbulence modeling and incorporates ideas from two-phase flow models. Clark and Spitz (1994) present a two-point model for variable-density turbulence. Their derivation is based on transport equations that, are based 0481 on two-point- generalizations of R{sub ij}, a{sub ij}, and b. These equations are Fourier transformed with respect to the separation distance between the two points. Transport equations are derived for R{sub ij}, a{sub i}, b. As in the one-point model, this model contains many ad-hoc assumptions and unknown model coefficients that must be determined by comparison with experimental and numerical data. However, the two-point formalism requires fewer equilibrium assumptions then does a single-point model. Our primary concern in this paper lies in the nonlinear processes of turbulence and the influence of large density variations (not within the Boussinesq limit) on these processes. To. isolate the effects of variable-density on the turbulence we restrict our flow to be incompressible, statistically homogeneous buoyancy-generated. turbulence. To our knowledge there have not been any simulations reported for this problem.

Sandoval, D.L.; Clark, T.T.; Riley, J.J.

1996-07-01T23:59:59.000Z

329

The dynamics of variable-density turbulence  

SciTech Connect

The dynamics of variable-density turbulent fluids are studied by direct numerical simulation. The flow is incompressible so that acoustic waves are decoupled from the problem, and implying that density is not a thermodynamic variable. Changes in density occur due to molecular mixing. The velocity field is, in general, divergent. A pseudo-spectral numerical technique is used to solve the equations of motion. Three-dimensional simulations are performed using a grid size of 128{sup 3} grid points. Two types of problems are studied: (1) the decay of isotropic, variable-density turbulence, and (2) buoyancy-generated turbulence in a fluid with large density fluctuations (such that the Boussinesq approximation is not valid). In the case of isotropic, variable-density turbulence, the overall statistical decay behavior, for the cases studied, is relatively unaffected by the presence of density variations when the initial density and velocity fields are statistically independent. The results for this case are in quantitative agreement with previous numerical and laboratory results. In this case, the initial density field has a bimodal probability density function (pdf) which evolves in time towards a Gaussian distribution. The pdf of the density field is symmetric about its mean value throughout its evolution. If the initial velocity and density fields are statistically dependent, however, the decay process is significantly affected by the density fluctuations. For this case, the pdf of the density becomes asymmetric about its mean value during the early stages of its evolution. It is argued that these asymmetries in the pdf of the density field are due to different entrainment rates, into the mixing region, that favor the high speed fluid.

Sandoval, D.L.

1995-11-01T23:59:59.000Z

330

Multivector Functions of a Multivector Variable  

E-Print Network (OSTI)

In this paper we develop with considerable details a theory of multivector functions of a $p$-vector variable. The concepts of limit, continuity and differentiability are rigorously studied. Several important types of derivatives for these multivector functions are introduced, as e.g., the $A$% -directional derivative (where $A$ is a $p$-vector) and the generalized concepts of curl, divergence and gradient. The derivation rules for different types of products of multivector functions and for compositon of multivector functions are proved.

A. M. Moya; V. V. Fernández; W. A. Rodrigues Jr

2002-12-18T23:59:59.000Z

331

Hidden Variables and Quantum Statistics Nature  

E-Print Network (OSTI)

It is shown that the nature of quantum statistics can be clarified by assuming the existence of a background of random gravitational fields and waves, distributed isotropically in the space. This background is responsible for correlating phases of oscillations of identical microobjects. If such a background of random gravitational fields and waves is considered as hidden variables then taking it into account leads to the Bell-type inequalities that are fairly consistent with the experimental data.

T. F. Kamalov

2007-03-14T23:59:59.000Z

332

Teleportation using continuous variable quantum cloning machine  

E-Print Network (OSTI)

We show that an unknown quantum state in phase space can be teleported via three-mode entanglement generated by continuous variable quantum cloning machine (transformation). Further, proceeding with our teleportation protocol we are able to improve the fidelity of teleportation obtained by Loock et.al. [Phys.Rev.Lett. 84, 3482(2000)]. Also we study here the entanglement between the two output copies from cloning machine.

Satyabrata Adhikari

2008-02-15T23:59:59.000Z

333

Is Salinity Variability a Benthic Disturbance?  

E-Print Network (OSTI)

include: salinity, pH, dissolved oxygen, temperature, conductivity, oxidation-reduction potential, and depth (Monatgna and Kalke 1992, 1995). Measurements were collected both at depth (0.1 m above bay bottom) and at the surface using a sonde... IS SALINITY VARIABILITY A BENTHIC DISTURBANCE? A Thesis by AMANDA D. VAN DIGGELEN Submitted to the Office of Graduate and Professional Studies of Texas A&M University and the Graduate Faculty of The Texas A&M University – Corpus...

Van Diggelen, Amanda

2014-05-07T23:59:59.000Z

334

Analysis of two basic variables of timeout  

E-Print Network (OSTI)

in reducing the rate of a designated behavior. Timeout from positive reinforcement is a behavior modification technique in which positive reinforcers are withdrawn for a period of time following a target response (White, Nielsen, and Johnson, 1972... variable (White, Nielsen, and Johnson, 1972) did not reach a decisive conclusion because of a sequencing problem in the method. The effects of three different timeout durations were investigated in a group of 20 retarded, institution- alized subjects...

Zella, William Francis

2012-06-07T23:59:59.000Z

335

SOLVING SYSTEMS OF NONLINEAR EQUATIONS WITH ...  

E-Print Network (OSTI)

Nov 2, 2006 ... an exothermic first-order irreversible reaction. When certain variables are eliminated, the model results in a system of two nonlinear equations.

2006-11-02T23:59:59.000Z

336

HIGH LEVEL WASTE SLUDGE BATCH 4 VARIABILITY STUDY  

SciTech Connect

The Defense Waste Processing Facility (DWPF) is preparing for vitrification of High Level Waste (HLW) Sludge Batch 4 (SB4) in early FY2007. To support this process, the Savannah River National Laboratory (SRNL) has provided a recommendation to utilize Frit 503 for vitrifying this sludge batch, based on the composition projection provided by the Liquid Waste Organization on June 22, 2006. Frit 418 was also recommended for possible use during the transition from SB3 to SB4. A critical step in the SB4 qualification process is to demonstrate the applicability of the durability models, which are used as part of the DWPF's process control strategy, to the glass system of interest via a variability study. A variability study is an experimentally-driven assessment of the predictability and acceptability of the quality of the vitrified waste product that is anticipated from the processing of a sludge batch. At the DWPF, the durability of the vitrified waste product is not directly measured. Instead, the durability is predicted using a set of models that relate the Product Consistency Test (PCT) response of a glass to the chemical composition of that glass. In addition, a glass sample is taken during the processing of that sludge batch, the sample is transmitted to SRNL, and the durability is measured to confirm acceptance. The objective of a variability study is to demonstrate that these models are applicable to the glass composition region anticipated during the processing of the sludge batch - in this case the Frit 503 - SB4 compositional region. The success of this demonstration allows the DWPF to confidently rely on the predictions of the durability/composition models as they are used in the control of the DWPF process.

Fox, K; Tommy Edwards, T; David Peeler, D; David Best, D; Irene Reamer, I; Phyllis Workman, P

2006-10-02T23:59:59.000Z

337

EPR-Steering measure for two-mode continuous variable states  

E-Print Network (OSTI)

Steering is a manifestation of quantum correlations that embodies the Einstein-Podolsky-Rosen (EPR) paradox. While there have been recent attempts to quantify steering, continuous variable systems remained elusive. We introduce a steering measure for two-mode continuous variable systems that is valid for arbitrary states. The measure is based on the violation of an optimized variance test for the EPR paradox, and admits a computable and experimentally friendly lower bound only depending on the second moments of the state, which reduces to a recently proposed quantifier of steerability by Gaussian measurements. We further show that Gaussian states are extremal with respect to our measure, minimizing it among all continuous variable states with fixed second moments. As a byproduct of our analysis, we generalize and relate well-known EPR-steering criteria. Finally an operational interpretation is provided, as the proposed measure is shown to quantify the optimal guaranteed key rate in semi-device independent qua...

Kogias, Ioannis

2014-01-01T23:59:59.000Z

338

EPR-Steering measure for two-mode continuous variable states  

E-Print Network (OSTI)

Steering is a manifestation of quantum correlations that embodies the Einstein-Podolsky-Rosen (EPR) paradox. While there have been recent attempts to quantify steering, continuous variable systems remained elusive. We introduce a steering measure for two-mode continuous variable systems that is valid for arbitrary states. The measure is based on the violation of an optimized variance test for the EPR paradox, and admits a computable and experimentally friendly lower bound only depending on the second moments of the state, which reduces to a recently proposed quantifier of steerability by Gaussian measurements. We further show that Gaussian states are extremal with respect to our measure, minimizing it among all continuous variable states with fixed second moments. As a byproduct of our analysis, we generalize and relate well-known EPR-steering criteria. Finally an operational interpretation is provided, as the proposed measure is shown to quantify the optimal guaranteed key rate in semi-device independent quantum key distribution.

Ioannis Kogias; Gerardo Adesso

2014-11-03T23:59:59.000Z

339

Infrared Properties of Cataclysmic Variables from 2MASS Results from the 2nd Incremental Data Release  

E-Print Network (OSTI)

Because accretion-generated luminosity dominates the radiated energy of most cataclysmic variables, they have been ``traditionally'' observed primarily at short wavelengths. Infrared observations of cataclysmic variables contribute to the understanding of key system components that are expected to radiate at these wavelengths, such as the cool outer disk, accretion stream, and secondary star. We have compiled the J, H, and Ks photometry of all cataclysmic variables located in the sky coverage of the 2 Micron All Sky Survey (2MASS) 2nd Incremental Data Release. This data comprises 251 systems with reliably identified near-IR counterparts and S/N > 10 photometry in one or more of the three near-IR bands.

Hoard, D W; Clark, L L; Bowers, T P; Bowers, Timothy P.

2001-01-01T23:59:59.000Z

340

Natural Gas Variability In California: Environmental Impacts And Device  

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

Natural Gas Variability In California: Environmental Impacts And Device Natural Gas Variability In California: Environmental Impacts And Device Performance - Experimental Evaluation Of Installed Cooking Exhaust Fan Performance Title Natural Gas Variability In California: Environmental Impacts And Device Performance - Experimental Evaluation Of Installed Cooking Exhaust Fan Performance Publication Type Report Year of Publication 2011 Authors Singer, Brett C., William W. Delp, and Michael G. Apte Publisher Lawrence Berkeley National Laboratory City Berkeley, CA Keywords energy analysis and environmental impacts department Abstract The installed performance of cooking exhaust fans was evaluated through residential field experiments conducted on a sample of 15 devices varying in design and other characteristics. The sample included two rear downdraft systems, two under-cabinet microwave over range units, three different installations of an under-cabinet model with grease screens across the bottom and no capture hood, two devices with grease screens covering the bottom of a large capture hood (one under-cabinet, one wall-mount chimney), four under-cabinet open hoods, and two open hoods with chimney mounts over islands. Performance assessment included measurement of airflow and sound levels across fan settings and experiments to quantify the contemporaneous capture efficiency for the exhaust generated by natural gas cooking burners. Capture efficiency is defined as the fraction of generated pollutants that are removed through the exhaust and thus not available for inhalation of household occupants. Capture efficiency was assessed for various configurations of burner use (e.g., single front, single back, combination of one front and one back, oven) and fan speed setting. Measured airflow rates were substantially lower than the levels noted in product literature for many of the units. This shortfall was observed for several units costing more than $1000. Capture efficiency varied widely (from < 5 percent to roughly 100 percent) across devices and across conditions for some devices. As expected, higher capture efficiencies were achieved with higher fan settings and the associated higher air flow rates. In most cases, capture efficiencies were substantially higher for rear burners than for front burners. The best and most consistent performance was observed for open hoods that covered all cooktop burners and operated at higher airflow rates. The lowest capture efficiencies were measured when a front burner was used with a rear backdraft system or with lowest fan setting for above-the-range systems that do not cover the front burners.

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


341

Variable speed wind turbine generator with zero-sequence filter  

DOE Patents (OSTI)

A variable speed wind turbine generator system to convert mechanical power into electrical power or energy and to recover the electrical power or energy in the form of three phase alternating current and return the power or energy to a utility or other load with single phase sinusoidal waveform at sixty (60) hertz and unity power factor includes an excitation controller for generating three phase commanded current, a generator, and a zero sequence filter. Each commanded current signal includes two components: a positive sequence variable frequency current signal to provide the balanced three phase excitation currents required in the stator windings of the generator to generate the rotating magnetic field needed to recover an optimum level of real power from the generator; and a zero frequency sixty (60) hertz current signal to allow the real power generated by the generator to be supplied to the utility. The positive sequence current signals are balanced three phase signals and are prevented from entering the utility by the zero sequence filter. The zero sequence current signals have zero phase displacement from each other and are prevented from entering the generator by the star connected stator windings. The zero sequence filter allows the zero sequence current signals to pass through to deliver power to the utility. 14 figs.

Muljadi, E.

1998-08-25T23:59:59.000Z

342

Variable Speed Wind Turbine Generator with Zero-sequence Filter  

DOE Patents (OSTI)

A variable speed wind turbine generator system to convert mechanical power into electrical power or energy and to recover the electrical power or energy in the form of three phase alternating current and return the power or energy to a utility or other load with single phase sinusoidal waveform at sixty (60) hertz and unity power factor includes an excitation controller for generating three phase commanded current, a generator, and a zero sequence filter. Each commanded current signal includes two components: a positive sequence variable frequency current signal to provide the balanced three phase excitation currents required in the stator windings of the generator to generate the rotating magnetic field needed to recover an optimum level of real power from the generator; and a zero frequency sixty (60) hertz current signal to allow the real power generated by the generator to be supplied to the utility. The positive sequence current signals are balanced three phase signals and are prevented from entering the utility by the zero sequence filter. The zero sequence current signals have zero phase displacement from each other and are prevented from entering the generator by the star connected stator windings. The zero sequence filter allows the zero sequence current signals to pass through to deliver power to the utility.

Muljadi, Eduard (Golden, CO)

1998-08-25T23:59:59.000Z

343

Variable speed wind turbine generator with zero-sequence filter  

DOE Patents (OSTI)

A variable speed wind turbine generator system to convert mechanical power into electrical power or energy and to recover the electrical power or energy in the form of three phase alternating current and return the power or energy to a utility or other load with single phase sinusoidal waveform at sixty (60) hertz and unity power factor includes an excitation controller for generating three phase commanded current, a generator, and a zero sequence filter. Each commanded current signal includes two components: a positive sequence variable frequency current signal to provide the balanced three phase excitation currents required in the stator windings of the generator to generate the rotating magnetic field needed to recover an optimum level of real power from the generator; and a zero frequency sixty (60) hertz current signal to allow the real power generated by the generator to be supplied to the utility. The positive sequence current signals are balanced three phase signals and are prevented from entering the utility by the zero sequence filter. The zero sequence current signals have zero phase displacement from each other and are prevented from entering the generator by the star connected stator windings. The zero sequence filter allows the zero sequence current signals to pass through to deliver power to the utility.

Muljadi, Eduard (Golden, CO)

1998-01-01T23:59:59.000Z

344

Solar Variability and Forecasting Jan Kleissl, Chi Chow, Matt Lave, Patrick Mathiesen,  

E-Print Network (OSTI)

renewables hard week: - small load - large renewables #12;Why does variability matter? Source: Andrew Mills.com/downloads/Session%205- 5_Sandia%20National%20Labs_Stein.pdf; Mills, A. et al. LBNL-2855E #12;PV Systems in San Diego Forecasting Benefits Use of state-of-art wind and solar forecasts reduces WECC operating costs by up to 14

Homes, Christopher C.

345

Increased Climate Variability Is More Visible Than Global Warming: A General  

E-Print Network (OSTI)

Increased Climate Variability Is More Visible Than Global Warming: A General System@utep.edu Abstract While global warming is a statistically confirmed long-term phenomenon, its most visible than the global warming itself. 1 Formulation of the Problem What is global warming. The term "global

Kreinovich, Vladik

346

UNDERSTANDING LCA RESULTS VARIABILITY: DEVELOPING GLOBAL SENSITIVITY ANALYSIS WITH SOBOL INDICES. A FIRST  

E-Print Network (OSTI)

UNDERSTANDING LCA RESULTS VARIABILITY: DEVELOPING GLOBAL SENSITIVITY ANALYSIS WITH SOBOL INDICES-06904 Sophia Antipolis Cedex, France Abstract LCA has been extensively used in the last few years in results of comparable systems. It somehow leads policy-makers to consider the LCA approach

Paris-Sud XI, Université de

347

Simplified Modelling and Control of a Synchronous Machine with VariableSpeed SixStep Drive  

E-Print Network (OSTI)

of electrical power flow in the machine. Cost is a driving factor in the design of such a system, and the power frequency than PWM as well. II. VARIABLE­SPEED ELECTRIC MACHINE DRIVES While the choice of driveSimplified Modelling and Control of a Synchronous Machine with Variable­Speed Six­Step Drive

Sanders, Seth

348

Integrated Analysis for the Design of Reusable TPS based on Variable Transpiration Cooling for Hypersonic Cruise  

E-Print Network (OSTI)

with the high dynamic pressure flight trajectories, generates surface temperatures for which the strength1 Integrated Analysis for the Design of Reusable TPS based on Variable Transpiration Cooling of hypersonic air-breathing vehicles presents formidable challenges. Reusable thermal protection systems (TPS

Texas at Arlington, University of

349

Ecology and the ratchet of events: Climate variability, niche dimensions, and species distributions  

E-Print Network (OSTI)

Ecology and the ratchet of events: Climate variability, niche dimensions, and species distributionsDepartment of Botany and Program in Ecology and dWyoming Water Resources Data System and Wyoming State Climate Office superimposed on anthropogenic trends. Predicting ecological and biogeographic responses to these changes

350

Energy-aware Allocation of Dynamic Variables in Partitioned Memory Architectures  

E-Print Network (OSTI)

Energy-aware Allocation of Dynamic Variables in Partitioned Memory Architectures Renato Levy This paper addresses the problem of minimizing the energy consumption by the memory subsystem in an embedded system. While significant work in the literature has addressed compiler driven energy aware allocation

Simha, Rahul

351

Time Variability of the "Quiet" Sun Observed  

Science Journals Connector (OSTI)

The Transition Region and Coronal Explorer (TRACE) observed a "quiet-Sun" region on 1999 February 17 from 02:15 UT to 3:00 UT with full resolution (05 pixel size), high cadence (125 s), and deep exposures (65 and 46 s) in the 171 Ĺ and 195 Ĺ wavelengths. We start our investigation of the time variability of "quiet-Sun" images with a detailed analysis of instrumental and nonsolar effects, such as orbital temperature variations, filtering of particle radiation spikes, spacecraft pointing drift, and solar rotation tracking. We quantify the magnitude of various noise components (photon Poisson statistics, data digitization, data compression, and readout noise) and establish an upper limit for the data noise level, above which temporal variability can safely be attributed to solar origin. We develop a pattern recognition code that extracts spatiotemporal events with significant variability, yielding a total of 3131 events in 171 Ĺ and 904 events in 195 Ĺ. We classify all 904 events detected in 195 Ĺ according to flarelike characteristics and establish a numerical flare criterion based on temporal, spatial, and dynamic cross-correlation coefficients between the two observed temperatures (0.9 and 1.4 MK). This numerical criterion matches the visual flare classification in 83% of the cases and can be used for automated flare search. Using this flare discrimination criterion we find that only 35% (and 25%) of the events detected in 171 (and 195) Ĺ represent flarelike events. The discrimination of flare events leads to a frequency distribution of peak fluxes, N(?F) ? ?F-1.83±0.07 at 195 Ĺ, which is significantly flatter than the distribution of all events. A sensitive discrimination criterion of flare events is therefore important for microflare statistics and for conclusions on their occurrence rate and efficiency for coronal heating.

Markus J. Aschwanden; Richard W. Nightingale; Ted D. Tarbell; C. J. Wolfson

2000-01-01T23:59:59.000Z

352

Impact of variable RBE on proton fractionation  

SciTech Connect

Purpose: To explore the impact of variable proton relative biological effectiveness (RBE) on dose fractionation for clinically relevant situations. A generic RBE = 1.1 is generally used for isoeffect calculations, while experimental studies showed that proton RBE varies with tissue type, dose, and linear energy transfer (LET). Methods: An analytical expression for the LET and {alpha}/{beta} dependence of the linear-quadratic (LQ) model has been used for proton simulations in parallel with the assumption of a generic RBE = 1.1. Calculations have been performed for ranges of LET values and fractionation sensitivities to describe clinically relevant cases, such as the treatment of head and neck and prostate tumors. Isoeffect calculations were compared with predictions from a generic RBE value and reported clinical results. Results: The generic RBE = 1.1 appears to be a reasonable estimate for the proton RBE of rapidly growing tissues irradiated with low LET radiation. However, the use of a variable RBE predicts larger differences for tissues with low {alpha}/{beta} (both tumor and normal) and at low doses per fraction. In some situations these differences may appear in contrast to the findings from photon studies highlighting the importance of accurate accounting for the radiobiological effectiveness of protons. Furthermore, the use of variable RBE leads to closer predictions to clinical results. Conclusions: The LET dependence of the RBE has a strong impact on the predicted effectiveness of fractionated proton radiotherapy. The magnitude of the effect is modulated by the fractionation sensitivity and the fractional dose indicating the need for accurate analyses both in the target and around it. Care should therefore be employed for changing clinical fractionation patterns or when analyzing results from clinical studies for this type of radiation.

Dasu, Alexandru; Toma-Dasu, Iuliana [Department of Radiation Physics UHL, County Council of Oestergoetland, 581 85 Linkoeping (Sweden) and Radiation Physics, Department of Medical and Health Sciences, Faculty of Health Sciences, Linkoeping University, 581 83 Linkoeping (Sweden); Medical Radiation Physics, Stockholm University and Karolinska Institute, 171 76 Stockholm (Sweden)

2013-01-15T23:59:59.000Z

353

Demand Response and Variable Generation Integration Scoping Study  

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

The Impact of City-level Permitting The Impact of City-level Permitting Processes on Residential PV Installation Prices and Development Times An Empirical Analysis of Solar Systems in California Cities Ryan Wiser and CG Dong Lawrence Berkeley National Laboratory April 2013 This analysis was funded by the Solar Energy Technologies Office, Office of Energy Efficiency and Renewable Energy of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231 Energy Analysis Department  Electricity Markets and Policy Group Presentation Overview * Questions and Objective * Literature Review * Data Sources and Processing * Variable Description and Summary * Regression Analysis Results * Interpretation and Predictions * Conclusions * Possible Future Extensions 2 Energy Analysis Department  Electricity Markets and Policy Group

354

Demand Response and Variable Generation Integration Scoping Study  

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

Market and Policy Barriers for Demand Market and Policy Barriers for Demand Response Providing Ancillary Services in U.S. Electricity Markets Peter Cappers, Jason MacDonald, Charles Goldman April 2013 Report Summary 1 Energy Analysis Department  Electricity Markets and Policy Group Presentation Overview  Objectives and Approach  Wholesale and Retail Market Environments  Market and Policy Barrier Typology  Prototypical Regional Barrier Assessment 2 Energy Analysis Department  Electricity Markets and Policy Group A Role for Demand Response to Provide Ancillary Services  Increasing penetration of renewable energy generation in U.S. electricity markets means that bulk power system operators will need to manage the variable and uncertain nature of many renewable resources

355

Variability Analysis of Complex Networks Measures based on Stochastic Distances  

E-Print Network (OSTI)

Complex networks can model the structure and dynamics of different types of systems. It has been shown that they are characterized by a set of measures. In this work, we evaluate the variability of complex networks measures face to perturbations and, for this purpose, we impose controlled perturbations and quantify their effect. We analyze theoretical models (random, small-world and scale-free) and real networks (a collaboration network and a metabolic networks) along with the shortest path length, vertex degree, local cluster coefficient and betweenness centrality measures. In such analysis, we propose the use of three stochastic quantifiers: the Kullback-Leibler divergence and the Jensen-Shannon and Hellinger distances. The sensitivity of these measures was analyzed with respect to the following perturbations: edge addition, edge removal, edge rewiring and node removal, all of them applied at different intensities. The results reveal that the evaluated measures are influenced by these perturbations. Additio...

Cabral, Raquel; Ramírez, Jaime

2014-01-01T23:59:59.000Z

356

Heart Rate Variability Analysis Using Threshold of Wavelet Package Coefficients  

E-Print Network (OSTI)

In this paper, a new efficient feature extraction method based on the adaptive threshold of wavelet package coefficients is presented. This paper especially deals with the assessment of autonomic nervous system using the background variation of the signal Heart Rate Variability HRV extracted from the wavelet package coefficients. The application of a wavelet package transform allows us to obtain a time-frequency representation of the signal, which provides better insight in the frequency distribution of the signal with time. A 6 level decomposition of HRV was achieved with db4 as mother wavelet, and the above two bands LF and HF were combined in 12 specialized frequencies sub-bands obtained in wavelet package transform. Features extracted from these coefficients can efficiently represent the characteristics of the original signal. ANOVA statistical test is used for the evaluation of proposed algorithm.

Kheder, G; Massoued, M Ben; Samet, M

2009-01-01T23:59:59.000Z

357

Method for curing polymers using variable-frequency microwave heating  

DOE Patents (OSTI)

A method for curing polymers incorporating a variable frequency microwave furnace system designed to allow modulation of the frequency of the microwaves introduced into a furnace cavity is disclosed. By varying the frequency of the microwave signal, non-uniformities within the cavity are minimized, thereby achieving a more uniform cure throughout the workpiece. A directional coupler is provided for detecting the direction of a signal and further directing the signal depending on the detected direction. A first power meter is provided for measuring the power delivered to the microwave furnace. A second power meter detects the magnitude of reflected power. The furnace cavity may be adapted to be used to cure materials defining a continuous sheet or which require compressive forces during curing. 15 figs.

Lauf, R.J.; Bible, D.W.; Paulauskas, F.L.

1998-02-24T23:59:59.000Z

358

Method for curing polymers using variable-frequency microwave heating  

DOE Patents (OSTI)

A method for curing polymers (11) incorporating a variable frequency microwave furnace system (10) designed to allow modulation of the frequency of the microwaves introduced into a furnace cavity (34). By varying the frequency of the microwave signal, non-uniformities within the cavity (34) are minimized, thereby achieving a more uniform cure throughout the workpiece (36). A directional coupler (24) is provided for detecting the direction of a signal and further directing the signal depending on the detected direction. A first power meter (30) is provided for measuring the power delivered to the microwave furnace (32). A second power meter (26) detects the magnitude of reflected power. The furnace cavity (34) may be adapted to be used to cure materials defining a continuous sheet or which require compressive forces during curing.

Lauf, Robert J. (Oak Ridge, TN); Bible, Don W. (Clinton, TN); Paulauskas, Felix L. (Oak Ridge, TN)

1998-01-01T23:59:59.000Z

359

Identification of building applications for a variable-conductance insulation  

SciTech Connect

Recent experiments have confirmed the feasibility of controllable, reversible disabling of a vacuum insulation panel, which may result in the development of energy-efficient building envelope components. These components could extend the managed energy exchange through the building envelope from about 30% (typical with fenestration systems in commercial buildings), to as much as 90% of the gross wall and roof areas. Further investigation will be required to optimized the thermal response and the magnitude of the R-value swing (from a difference between insulating and conducting insulating values of 4 to as high as a factor of 100). The potential for energy reduction by using the variable-conductance insulation in the building envelope is discussed, and other potential building applications are mentioned.

Potter, T.F. [National Renewable Energy Lab., Golden, CO (United States); Tuluca, A. [Winter (Steven) Associates, Inc., New York, NY (United States)

1992-07-01T23:59:59.000Z

360

Adhesive bonding using variable frequency microwave energy  

DOE Patents (OSTI)

Methods of facilitating the adhesive bonding of various components with variable frequency microwave energy are disclosed. The time required to cure a polymeric adhesive is decreased by placing components to be bonded via the adhesive in a microwave heating apparatus having a multimode cavity and irradiated with microwaves of varying frequencies. Methods of uniformly heating various articles having conductive fibers disposed therein are provided. Microwave energy may be selectively oriented to enter an edge portion of an article having conductive fibers therein. An edge portion of an article having conductive fibers therein may be selectively shielded from microwave energy.

Lauf, Robert J. (Oak Ridge, TN); McMillan, April D. (Knoxville, TN); Paulauskas, Felix L. (Oak Ridge, TN); Fathi, Zakaryae (Cary, NC); Wei, Jianghua (Raleigh, NC)

1998-01-01T23:59:59.000Z

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


361

Adhesive bonding using variable frequency microwave energy  

DOE Patents (OSTI)

Methods of facilitating the adhesive bonding of various components with variable frequency microwave energy are disclosed. The time required to cure a polymeric adhesive is decreased by placing components to be bonded via the adhesive in a microwave heating apparatus having a multimode cavity and irradiated with microwaves of varying frequencies. Methods of uniformly heating various articles having conductive fibers disposed therein are provided. Microwave energy may be selectively oriented to enter an edge portion of an article having conductive fibers therein. An edge portion of an article having conductive fibers therein may be selectively shielded from microwave energy. 26 figs.

Lauf, R.J.; McMillan, A.D.; Paulauskas, F.L.; Fathi, Z.; Wei, J.

1998-09-08T23:59:59.000Z

362

Adhesive bonding using variable frequency microwave energy  

DOE Patents (OSTI)

Methods of facilitating the adhesive bonding of various components with variable frequency microwave energy are disclosed. The time required to cure a polymeric adhesive is decreased by placing components to be bonded via the adhesive in a microwave heating apparatus having a multimode cavity and irradiated with microwaves of varying frequencies. Methods of uniformly heating various articles having conductive fibers disposed therein are provided. Microwave energy may be selectively oriented to enter an edge portion of an article having conductive fibers therein. An edge portion of an article having conductive fibers therein may be selectively shielded from microwave energy. 26 figs.

Lauf, R.J.; McMillan, A.D.; Paulauskas, F.L.; Fathi, Z.; Wei, J.

1998-08-25T23:59:59.000Z

363

Dynamical variables in Gauge-Translational Gravity  

E-Print Network (OSTI)

Assuming that the natural gauge group of gravity is given by the group of isometries of a given space, for a maximally symmetric space we derive a model in which gravity is essentially a gauge theory of translations. Starting from first principles we verify that a nonlinear realization of the symmetry provides the general structure of this gauge theory, leading to a simple choice of dynamical variables of the gravity field corresponding, at first order, to a diagonal matrix, whereas the non-diagonal elements contribute only to higher orders.

J. Julve; A. Tiemblo

2010-07-02T23:59:59.000Z

364

A variable parameter thermionic energy converter  

E-Print Network (OSTI)

A VARIABLE PARAMETER THERMIONIC ENERGY CONVERTER A Thesis By Bobby Joe Bragg Submitted to the Graduate School of the Texas A 8c M University in partial fulfillment of the requirement for the degree of MASTER OF SCIENCE August, 1967 Major... LIST OF FIGURES FIGURE 1. SIMPLE SCHEMATIC OF A THERMIONIC CONVERTER PAGE 2. POWER VS SPACING WITH A MINIMUM POWER POINT 3. POWER VS SPACING WITH NO MINIMUM POWER POINT 4. CONVERTER MOTIVE DIAGRAM~ O'E = 5. CONVERTER MOTIVE DIAGRAM~ 6. CONVERTER...

Bragg, Bobby Joe

1967-01-01T23:59:59.000Z

365

The future of massive variability searches  

E-Print Network (OSTI)

This is a personal review of various issues related to massive photometric and astrometric searches. A complete inventory of variable stars down to almost any magnitude limit will improve our understanding of the stellar evolution and the galactic structure. A search for detached eclipsing binaries will improve the distance scale, the value of the Hubble constant, and the age of the oldest stars. A search for supernovae will help the determination of cosmological parameters Omega and Lambda. A search for microlensing events will provide insight into the stellar mass function, dark matter, and may lead to a discovery of earth-mass planets.

Paczynski, B

1996-01-01T23:59:59.000Z

366

Crystal diffraction lens with variable focal length  

DOE Patents (OSTI)

A method and apparatus for altering the focal length of a focusing element of one of a plurality of pre-determined focal lengths by changing heat transfer within selected portions of the element by controlled quantities is disclosed. Control over heat transfer is accomplished by manipulating one or more of a number of variables, including: the amount of heat or cold applied to surfaces; type of fluids pumped through channels for heating and cooling; temperatures, directions of flow and rates of flow of fluids; and placement of channels. 19 figures.

Smither, R.K.

1991-04-02T23:59:59.000Z

367

Chi-Variable-Speed-of-Light Cosmologies  

E-Print Network (OSTI)

Variable-Speed-of-Light (VSL) cosmologies are currently attracting much interest as a possible alternative to cosmological inflation. We discuss the fundamental geometrodynamic aspects of VSL cosmologies, and provide several alternative implementations. These implementations provide a large class of VSL cosmologies that pass the zeroth-order consistency tests of being compatible with both classical Einstein gravity and low-energy particle physics. While they solve the ``kinematic'' puzzles as well as inflation does, VSL cosmologies typically do not solve the flatness problem since in their purest form no violation of the strong energy condition occurs. Nevertheless, these models are easy to unify with inflation.

Stefano Liberati; Bruce A. Bassett; Carmen Molina-Paris; Matt Visser

2000-01-27T23:59:59.000Z

368

An ultrasonic transducer transient compensator design based on a simplified Variable Structure Control algorithm  

Science Journals Connector (OSTI)

Abstract A non-linear control method, known as Variable Structure Control (VSC), is employed to reduce the duration of ultrasonic (US) transducer transients. A physically realizable system using a simplified form of the VSC algorithm is proposed for standard piezoelectric transducers and simulated. Results indicate a VSC-controlled transmitter reduces the transient duration to less than a carrier wave cycle. Applications include high capacity ultrasound communication and localization systems.

Shaodong Ma; Antony J. Wilkinson; Kevin S. Paulson

2014-01-01T23:59:59.000Z

369

Shape Changing and Accelerating Solitons in the Integrable Variable Mass Sine-Gordon Model  

SciTech Connect

The sine-Gordon model with a variable mass (VMSG) appears in many physical systems, ranging from the current through a nonuniform Josephson junction to DNA-promoter dynamics. Such models are usually nonintegrable with solutions found numerically or perturbatively. We construct a class of VMSG models, integrable at both the classical and the quantum levels with exact soliton solutions, which can accelerate and change their shape, width, and amplitude simulating realistic inhomogeneous systems at certain limits.

Kundu, Anjan [Theory Group, Saha Institute of Nuclear Physics, Calcutta (India)

2007-10-12T23:59:59.000Z

370

Intraseasonal variability in South America recorded in stable water isotopes  

E-Print Network (OSTI)

Intraseasonal variability in South America recorded in stable water isotopes Christophe Sturm,1 cores (South America) has illustrated the key role such archives can play in past climate South America, highlighting the internal atmospheric variability, as opposed to external forcing

Sturm, Christophe "Kristof"

371

Wave spectral energy variability in the northeast Peter D. Bromirski  

E-Print Network (OSTI)

Wave spectral energy variability in the northeast Pacific Peter D. Bromirski Integrative January 2005; published 8 March 2005. [1] The dominant characteristics of wave energy variability] s wave spectral energy components are considered separately. Empirical orthogonal function (EOF) analyses

Bromirski, Peter D.

372

Bayesian variable selection in clustering via dirichlet process mixture models  

E-Print Network (OSTI)

simultane- ously. I use Dirichlet process mixture models to define the cluster structure and to introduce in the model a latent binary vector to identify discriminating variables. I update the variable selection index using a Metropolis algorithm and obtain...

Kim, Sinae

2007-09-17T23:59:59.000Z

373

Atlantic Climate Variability and Predictability: A CLIVAR Perspective  

Science Journals Connector (OSTI)

Three interrelated climate phenomena are at the center of the Climate Variability and Predictability (CLIVAR) Atlantic research: tropical Atlantic variability (TAV), the North Atlantic Oscillation (NAO), and the Atlantic meridional overturning ...

J. W. Hurrell; M. Visbeck; A. Busalacchi; R. A. Clarke; T. L. Delworth; R. R. Dickson; W. E. Johns; K. P. Koltermann; Y. Kushnir; D. Marshall; C. Mauritzen; M. S. McCartney; A. Piola; C. Reason; G. Reverdin; F. Schott; R. Sutton; I. Wainer; D. Wright

2006-10-01T23:59:59.000Z

374

Integrating Variable Renewable Energy in Electric Power Markets: Best Practices from International Experience  

SciTech Connect

Many countries -- reflecting very different geographies, markets, and power systems -- are successfully managing high levels of variable renewable energy on the electric grid, including that from wind and solar energy. This study documents the diverse approaches to effective integration of variable renewable energy among six countries -- Australia (South Australia), Denmark, Germany, Ireland, Spain, and the United States (Western region-Colorado and Texas)-- and summarizes policy best practices that energy ministers and other stakeholders can pursue to ensure that electricity markets and power systems can effectively coevolve with increasing penetrations of variable renewable energy. Each country has crafted its own combination of policies, market designs, and system operations to achieve the system reliability and flexibility needed to successfully integrate renewables. Notwithstanding this diversity, the approaches taken by the countries studied all coalesce around five strategic areas: lead public engagement, particularly for new transmission; coordinate and integrate planning; develop rules for market evolution that enable system flexibility; expand access to diverse resources and geographic footprint of operations; and improve system operations. The ability to maintain a broad ecosystem perspective, to organize and make available the wealth of experiences, and to ensure a clear path from analysis to enactment should be the primary focus going forward.

Cochran, J.; Bird, L.; Heeter, J.; Arent, D. A.

2012-04-01T23:59:59.000Z

375

Robust Shot Noise Measurement for Continuous Variable Quantum Key Distribution  

E-Print Network (OSTI)

We study a practical method to monitor in real-time the behavior of a Continuous Variable Quantum Key Distribution (CVQKD) system, and especially the shot noise measurement procedure, for the presence of an eavesdropper. The amount of secret key that can be extracted from the raw statistics of a CVQKD system depends strongly on a shot noise estimate since this quantity affects in particular the computation of the excess noise (i.e. noise in excess of the shot noise) added by an eavesdropper on the quantum channel. Some powerful quantum hacking attacks rely on faking the estimated value of the shot noise to hide an intercept-and-resend eavesdropping strategy, notably by targeting the calibration of the system, the saturation of the homodyne detection device or the wavelength dependency of some optical components. We describe a new countermeasure that consists in fairly general statistical tests build on top of an existing real-time shot-noise measurement technique and show that it is able to defeat all these attacks.

Sébastien Kunz-Jacques; Paul Jouguet

2014-06-29T23:59:59.000Z

376

On adaptive grid computations of variable stars  

SciTech Connect

We show that the use of an implicit adaptive-grid technique is an efficient and up-to-date approach for the calculations of radial oscillations in variable stars. We chose as an illustrative example the radiative envelope of an RR Lyrae variable. For the hydrostatic initial model we compare the Lagrangean ratioed zoning with an adaptive-grid rezoning. We show that the adaptive-grid yields an optimal distribution of the mesh points in the sense that the relevant physical features, the H{minus} and He 1{minus}, He 2{minus} ionization zones, are well resolved. For the hydrodynamical evolution we present the full-amplitude model for both the Lagrangean and adaptive-grid computations. We perform a detailed comparison and show that the adaptive-grid method yields limit cycle solutions that are substantially improved over the Lagrangean grid model. This is due to the fact that the Lagrangean mesh sweeps through the ionization zones twice during one oscillation period, whereas the adaptive-mesh resolves them and tracks them continuously. The results are, in particular, smooth radial velocity and light curves. Beyond a physically better defined solution we also observe larger time steps for the convergence towards the limit cycle and for the evolution during one period. 12 refs., 13 figs., 5 tabs.

Cox, A.N.; Deupree, R.G.; Gehmeyr, M.

1991-01-01T23:59:59.000Z

377

Dynamical dark energy or variable cosmological parameters?  

E-Print Network (OSTI)

One of the main aims in the next generation of precision cosmology experiments will be an accurate determination of the equation of state (EOS) for the dark energy (DE). If the latter is dynamical, the resulting barotropic index \\omega should exhibit a non-trivial evolution with the redshift. Usually this is interpreted as a sign that the mechanism responsible for the DE is related to some dynamical scalar field, and in some cases this field may behave non-canonically (phantom field). Present observations seem to favor an evolving DE with a potential phantom phase near our time. In the literature there is a plethora of dynamical models trying to describe this behavior. Here we show that the simplest option, namely a model with a variable cosmological term, \\Lambda=\\Lambda(t), leads in general to a non-trivial effective EOS, with index \\omega_e, which may naturally account for these data features. We prove that in this case there is always a ``crossing'' of the \\omega_e=-1 barrier near our time. We also show how this effect is modulated (or even completely controled) by a variable Newton's constant G=G(t).

Joan Sola; Hrvoje Stefancic

2005-12-21T23:59:59.000Z

378

Variably insulating portable heater/cooler  

DOE Patents (OSTI)

A compact vacuum insulation panel comprising a chamber enclosed by two sheets of metal, glass-like spaces disposed in the chamber between the sidewalls, and a high-grade vacuum in the chamber includes apparatus and methods for enabling and disabling, or turning "on" and "off" the thermal insulating capability of the panel. One type of enabling and disabling apparatus and method includes a metal hydride for releasing hydrogen gas into the chamber in response to heat, and a hydrogen grate between the metal hydride and the chamber for selectively preventing and allowing return of the hydrogen gas to the metal hydride. Another type of enabling and disabling apparatus and method includes a variable emissivity coating on the sheets of metal in which the emissivity is controllably variable by heat or electricity. Still another type of enabling and disabling apparatus and method includes metal-to-metal contact devices that can be actuated to establish or break metal-to-metal heat paths or thermal short circuits between the metal sidewalls.

Potter, Thomas F. (Denver, CO)

1998-01-01T23:59:59.000Z

379

Variably insulating portable heater/cooler  

DOE Patents (OSTI)

A compact vacuum insulation panel is described comprising a chamber enclosed by two sheets of metal, glass-like spaces disposed in the chamber between the sidewalls, and a high-grade vacuum in the chamber includes apparatus and methods for enabling and disabling, or turning ``on`` and ``off`` the thermal insulating capability of the panel. One type of enabling and disabling apparatus and method includes a metal hydride for releasing hydrogen gas into the chamber in response to heat, and a hydrogen grate between the metal hydride and the chamber for selectively preventing and allowing return of the hydrogen gas to the metal hydride. Another type of enabling and disabling apparatus and method includes a variable emissivity coating on the sheets of metal in which the emissivity is controllably variable by heat or electricity. Still another type of enabling and disabling apparatus and method includes metal-to-metal contact devices that can be actuated to establish or break metal-to-metal heat paths or thermal short circuits between the metal sidewalls. 25 figs.

Potter, T.F.

1998-09-29T23:59:59.000Z

380

Variable Speed of Light Research Project Dave Schumann  

E-Print Network (OSTI)

Variable Speed of Light Research Project Dave Schumann Dr. Bharath Narayanan 21 September 2003 mathematics of the Variable Speed of Light (VSL) theory. In a paper titled, "A Time Varying Speed of Light of a variable speed of light in the early stages of the universe. They propose corrections to the cosmological

Zakharov, Vladimir

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


381

Unifying parameter estimation and the Deutsch-Jozsa algorithm for continuous variables  

E-Print Network (OSTI)

We reveal a close relationship between quantum metrology and the Deutsch-Jozsa algorithm on continuous variable quantum systems. We develop a general procedure, characterized by two parameters, that unifies parameter estimation and the Deutsch-Jozsa algorithm. Depending on which parameter we keep constant, the procedure implements either the parameter estimation protocol or the Deutsch-Jozsa algorithm. The parameter estimation part of the procedure attains the Heisenberg limit and is therefore optimal. Due to the use of approximate normalizable continuous variable eigenstates the Deutsch-Jozsa algorithm is probabilistic. The procedure estimates a value of an unknown parameter and solves the Deutsch-Jozsa problem without the use of any entanglement.

Marcin Zwierz; Carlos A. Pérez-Delgado; Pieter Kok

2010-08-19T23:59:59.000Z

382

Performance of convergence-based variable-gain control of optical storage drives  

Science Journals Connector (OSTI)

In this paper, a method for the performance assessment of a variable-gain control design for optical storage drives is proposed. The variable-gain strategy is used to overcome well-known linear control design trade-offs between low-frequency tracking properties and high-frequency noise sensitivity. A convergence-based control design is proposed that guarantees stability of the closed-loop system and a unique bounded steady-state response for any bounded disturbance. These favourable properties, guaranteed by virtue of convergence, allow for a unique performance evaluation of the control system. Moreover, technical conditions for convergence are derived for the variable-gain controlled system and a quantitative performance measure, taking into account both low-frequency tracking properties and high-frequency measurement noise sensitivity, is proposed. The convergence conditions together with the performance measure jointly constitute a design tool for tuning the parameters of the variable-gain controller. The resulting design is shown to outperform linear control designs.

N. van de Wouw; H.A. Pastink; M.F. Heertjes; A.V. Pavlov; H. Nijmeijer

2008-01-01T23:59:59.000Z

383

What measures climate? A variety of variables including their variability and extreme values determine climate for  

E-Print Network (OSTI)

climate zones? The sun is the ultimate power source for the climate "machine". The uneven distribution conditions. Typical variables to consider are temperature (maximum, miniumum), precipitation (includes rain, sleet, snow, hail, etc), sunlight/cloudiness, wind, humidity, ice cover, sea temperature, etc... Many

Allan, Richard P.

384

The TAOS Project Stellar Variability II. Detection of 15 Variable Stars  

SciTech Connect

The Taiwanese-American Occultation Survey (TAOS) project has collected more than a billion photometric measurements since 2005 January. These sky survey data - covering timescales from a fraction of a second to a few hundred days - are a useful source to study stellar variability. A total of 167 star fields, mostly along the ecliptic plane, have been selected for photometric monitoring with the TAOS telescopes. This paper presents our initial analysis of a search for periodic variable stars from the time-series TAOS data on one particular TAOS field, No. 151 (RA = 17{sup h} 30{sup m} 6.67{sup s}, Dec = 27 degrees, 17 minutes, 30 seconds, J2000), which had been observed over 47 epochs in 2005. A total of 81 candidate variables are identified in the 3 square degree field, with magnitudes in the range 8 < R < 16. On the basis of the periodicity and shape of the lightcurves, 32 variables, 18 of which were previously unknown, are classified as RR Lyrae, Cepheid, {delta} Scuti, SX Phonencis, semi-regular and eclipsing binaries.

Mondal, S; Lin, C C; Zhang, Z W; Alcock, C; Axelrod, T; Bianco, F B; Byun, Y I; Coehlo, N K; Cook, K H; Dave, R; Kim, D W; King, S K; Lee, T; Lehner, M J; Lin, H C; Marshall, S L; Protopapas, P; Rice, J A; Schwamb, M E; Wang, J H; Wang, S Y; Wen, C Y

2010-01-28T23:59:59.000Z

385

Variable Temperature UHV STM/AFM | EMSL  

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

a novel model early transition metal oxide system for catalysis studies—direct sublimation of... Direct Visualization of 2-Butanol Adsorption and Dissociation on...

386

The Deep Lens Survey Transient Search I : Short Timescale and Astrometric Variability  

E-Print Network (OSTI)

We report on the methodology and first results from the Deep Lens Survey transient search. We utilize image subtraction on survey data to yield all sources of optical variability down to 24th magnitude. Images are analyzed immediately after acquisition, at the telescope and in near-real time, to allow for followup in the case of time-critical events. All classes of transients are posted to the web upon detection. Our observing strategy allows sensitivity to variability over several decades in timescale. The DLS is the first survey to classify and report all types of photometric and astrometric variability detected, including solar system objects, variable stars, supernovae, and short timescale phenomena. Three unusual optical transient events were detected, flaring on thousand-second timescales. All three events were seen in the B passband, suggesting blue color indices for the phenomena. One event (OT 20020115) is determined to be from a flaring Galactic dwarf star of spectral type dM4. From the remaining two events, we find an overall rate of \\eta = 1.4 events deg-2 day-1 on thousand-second timescales, with a 95% confidence limit of \\eta < 4.3. One of these events (OT 20010326) originated from a compact precursor in the field of galaxy cluster Abell 1836, and its nature is uncertain. For the second (OT 20030305) we find strong evidence for an extended extragalactic host. A dearth of such events in the R passband yields an upper 95% confidence limit on short timescale astronomical variability between 19.5 < R < 23.4 of \\eta_R < 5.2. We report also on our ensemble of astrometrically variable objects, as well as an example of photometric variability with an undetected precursor.

A. C. Becker; D. M. Wittman; P. C. Boeshaar; A. Clocchiatti; I. P. Dell'Antonio; D. A. Frail; J. Halpern; V. E. Margoniner; D. Norman; J. A. Tyson; R. A. Schommer

2004-04-21T23:59:59.000Z

387

Variable-field permanent magnet dipole  

SciTech Connect

A new concept for a variable-field permanent-magnet dipole (VFPMD) has been designed, fabricated, and tested at Los Alamos. The VFPMD is a C-shaped sector magnet with iron poles separated by a large block of magnet material (SmCo). The central field can be continuously varied from 0.07 T to 0.3 T by moving an iron shunt closer or further away from the back of the magnet. The shunt is specially shaped to make the dependence of the dipole field strength on the shunt position as linear as possible. The dipole has a 2.8 cm high by 8 cm wide aperture with {approximately}10 cm long poles.

Barlow, D.B.; Kraus, R.H. Jr.; Meyer, R.E.

1993-10-01T23:59:59.000Z

388

Dissecting magnetar variability with Bayesian hierarchical models  

E-Print Network (OSTI)

Neutron stars are a prime laboratory for testing physical processes under conditions of strong gravity, high density, and extreme magnetic fields. Among the zoo of neutron star phenomena, magnetars stand out for their bursting behaviour, ranging from extremely bright, rare giant flares to numerous, less energetic recurrent bursts. The exact trigger and emission mechanisms for these bursts are not known; favoured models involve either a crust fracture and subsequent energy release into the magnetosphere, or explosive reconnection of magnetic field lines. In the absence of a predictive model, understanding the physical processes responsible for magnetar burst variability is difficult. Here, we develop an empirical model that decomposes magnetar bursts into a superposition of small spike-like features with a simple functional form, where the number of model components is itself part of the inference problem. The cascades of spikes that we model might be formed by avalanches of reconnection, or crust rupture afte...

Huppenkothen, D; Hogg, D W; Murray, I; Frean, M; Elenbaas, C; Watts, A L; Levin, Y; van der Horst, A J; Kouveliotou, C

2015-01-01T23:59:59.000Z

389

Improvements of the Variable Thermal Resistance  

E-Print Network (OSTI)

A flat mounting unit with electronically variable thermal resistance [1] has been presented in the last year [2]. The design was based on a Peltier cell and the appropriate control electronics and software. The device is devoted especially to the thermal characterization of packages, e.g. in dual cold plate arrangements. Although this design meets the requirements of the static measurement we are intended to improve its parameters as the settling time and dynamic thermal impedance and the range of realized thermal resistance. The new design applies the heat flux sensor developed by our team as well [3], making easier the control of the device. This development allows even the realization of negative thermal resistances.

V. Szekely; S. Torok; E. Kollar

2008-01-07T23:59:59.000Z

390

Dark matter interacts with variable vacuum energy  

E-Print Network (OSTI)

We investigate a spatially flat Friedmann-Robertson-Walker (FRW) scenario with two interacting components, dark matter and variable vacuum energy (VVE) densities, plus two decoupled components, one is a baryon term while the other behaves as a radiation component. We consider a linear interaction in the derivative dark component density. We apply the $\\chi^2$ method to the observational Hubble data for constraining the cosmological parameters and analyze the amount of dark energy in the radiation era for the model. It turns out that our model fulfills the severe bound of $\\Omega_{x}(z\\simeq 1100)survey, the future constraints achievable by Euclid and CMBPol experiments, reported for the behavior of the dark energy at early times, and fulfills the stringent bound $\\Omega_{x}(z\\simeq 10^{10})<0.04$ at $2\\sigma$ level in the big-bang nucleosynthesis epoch. We a...

G, Iván E Sánchez

2014-01-01T23:59:59.000Z

391

Modular design of biological systems  

E-Print Network (OSTI)

The focus of my research is the development of technology for building compound biological systems from simpler pieces. I designed BioScaffold parts, a family of variable regions that can be inserted into a DNA sequence ...

Norville, Julie Erin, 1980-

2012-01-01T23:59:59.000Z

392

Building Technologies Office: Advanced, Variable Speed Air-Source  

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

Advanced, Variable Advanced, Variable Speed Air-Source Integrated Heat Pumps Research Project to someone by E-mail Share Building Technologies Office: Advanced, Variable Speed Air-Source Integrated Heat Pumps Research Project on Facebook Tweet about Building Technologies Office: Advanced, Variable Speed Air-Source Integrated Heat Pumps Research Project on Twitter Bookmark Building Technologies Office: Advanced, Variable Speed Air-Source Integrated Heat Pumps Research Project on Google Bookmark Building Technologies Office: Advanced, Variable Speed Air-Source Integrated Heat Pumps Research Project on Delicious Rank Building Technologies Office: Advanced, Variable Speed Air-Source Integrated Heat Pumps Research Project on Digg Find More places to share Building Technologies Office: Advanced,

393

Periodic Flux Variability of Stars due to the Reflex Doppler Effect Induced by Planetary Companions  

E-Print Network (OSTI)

Upcoming space-based photometric satellites offer the possibility of detecting continuum flux variability at the micro-magnitude level. We show that the Doppler flux variability induced by the reflex motion of stars due to planetary companions has an amplitude of (3-alpha)K/c, where K is the reflex radial velocity amplitude and alpha is the logarithmic slope of source spectral flux in the observed frequency band. For many of the known close-in planetary systems with periods less than ~0.2 years, the periodic Doppler variability is of order a micromagnitude, and is significant relative to the variability caused by reflected light from the planetary companion. For companions with periods greater than ~0.2 years, the Doppler signal is larger than the reflected light signal. We show that the future photometric satellites should reach the sensitivity to detect this Doppler variability. In particular, the Kepler satellite should have the photon-noise sensitivity to detect at a signal-to-noise ratio > 5, all planets with minimum mass greater than 5 Jupiter masses, and periods less than 0.1 years around the 10,000 main-sequence stars with spectral types A through K and apparent magnitude V<12 in its field-of-view.

Abraham Loeb; B. Scott Gaudi

2003-03-10T23:59:59.000Z

394

Modeling and Experimental Investigation of a Variable Speed Drive Water Source Heat Pump  

Science Journals Connector (OSTI)

Accurate variable speed characteristics are needed for water source heat pumps (WSHP) to design variable speed controls to adjust refrigerant flow rates in heat pumps and air conditioners. The system capacity can then be regulated to match the compressor loads to the heating or cooling needs to improve the energy efficiency and lower energy costs. The motor and compression characteristics of WSHP were modeled to include the coupling between the motor speed and the torque characteristics and compression characteristics. An analytical model is given for a variable speed hermetic scroll compressor that describes various factors, such as the drive frequency, suction pressure, and discharge pressure as a function of the compressor speed. The model was validated experimentally using R22 and \\{R134a\\} in an experimental WSHP with variable speed control using frequency conversion. The results show that the analytical model properly describes the variable speed characteristics and provides a control strategy for adjusting the capacity of scroll compressors to match the heat pump or air conditioner operating conditions.

Zhifang Xue; Lin Shi

2010-01-01T23:59:59.000Z

395

Comparison of energy efficiency between variable refrigerant flow systems and ground source heat pump systems  

E-Print Network (OSTI)

simulation with credible software programs is a proven feasible way to get quantitative comparison of the energy

Hong, Tainzhen

2010-01-01T23:59:59.000Z

396

Comparison of energy efficiency between variable refrigerant flow systems and ground source heat pump systems  

E-Print Network (OSTI)

the current movement toward net zero energy buildings, manyThe movement towards net zero energy buildings brings

Hong, Tainzhen

2010-01-01T23:59:59.000Z

397

NERSC File Systems  

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

Systems Systems NERSC File Systems Overview NERSC file systems can be divided into two categories: local and global. Local file systems are only accessible on a single platform, providing best performance; global file systems are accessible on multiple platforms, simplifying data sharing between platforms. File systems are configured for different purposes. On each machine you have access to at least three different file system Home: Permanent, relatively small storage for data like source code, shell scripts, etc. that you want to keep. This file system is not tuned for high performance from parallel jobs. Referenced by the environment variable $HOME. Scratch: Large, high-performance file system. Place your large data files in this file system for capacity and capability computing. Data is

398

Modeling turbo-expander systems  

Science Journals Connector (OSTI)

Turbo-expander systems have long been used instead of regulators, but they have recently received attention as a driving medium for power electrical generators. These systems typically replace the regulator valves that reduce the gas pressure in gas ... Keywords: dispersed generation, turbo-expander systems, variable nozzle angle

Mehdi Taleshian Jelodar; Hasan Rastegar; Hossein Askarian Abyaneh

2013-02-01T23:59:59.000Z

399

Robust combinatorial optimization with variable budgeted uncertainty  

E-Print Network (OSTI)

system of constraints, the resulting optimization problems are of the same com- ... protecting the associated ambiguous chance constraint with the same ...... test their sample average approximation algorithm and Fortz et al (2012) use the.

2012-10-15T23:59:59.000Z

400

Plant variability and bio-fuel properties  

SciTech Connect

Thermochemically converting biomass feedstocks to fuels is one of the major thrusts of renewable energy research at the National Renewable Energy Laboratory. Among several thermochemical routes is the fast pyrolysis process which produces liquid fuels from woody and herbaceous biomass feedstocks. Because of the large variability in the composition of biomass feedstocks due to plant variety and environmental factors, it is important to assess how these variabilities affect the properties of thermochemical liquid fuels (bio-oils) produced from these resources. Similar varieties of switchgrass (Panicum virgatum L.) that were grown at three different locations and three hybrid poplar clones that were grown at one location were used in these studies. The feedstocks were pyrolyzed in a fluidized bed reactor at 500{degrees}C. The gas products were analyzed on-line and the liquid products were analyzed for elemental composition and higher heating values. Apart from small difference in the yield of char/ash, the yields of pyrolysis oils and gases were similar for switchgrass feedstocks grown at all three locations. The char/ash yields ranged from 21.1 to 22.9%; total liquids (organic liquids + water) yields ranged from 59%-60.5%; and the gas yields ranged from 11%-12% (wt). The higher heating values (HHVs) of the oils were similar (24.3-24.6 MJ/kg). For the hybrid poplar feedstocks, total liquids (65%-69%), char/ash (10%-11%), and gas yields (15.6%-17%) were similar for all three poplar clones; however, the elemental composition and the HHVs of the pyrolysis oils had statistically significant differences. The NC5260 pyrolysis oils had lower HHV (22.0{+-}0.5 MG/kg) compared to the DN clones (23.2{+-}0.3 MJ/kg). The yields of total liquids and organics for the three clones were higher than those for the switchgrass feedstocks. The gas yields for the hybrid poplar clones were higher than for the switchgrass, but had compositions similar to those of the switchgrass feedstocks.

Agblevor, F.A.; Besler-Guran, S.; Wiselogel, A.E. [National Renewable Energy Lab., Golden, CO (United States)

1995-11-01T23:59:59.000Z

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


401

Parameterization of daily solar irradiance variability  

Science Journals Connector (OSTI)

The effects of solar systems operation can be compared only under very similar weather conditions. Diagnostics of the solar systems requires unequivocal determination of solar irradiation. Development of a method for precise identification of solar radiation day time profile is needed, as the methods used so far in the cloud cover determination are not satisfactory. The paper presents two optional methods, developed by the authors, for identification of the solar radiation profile. Advantages and disadvantages of the methods are also specified.

D. Czekalski; A. Chochowski; P. Obstawski

2012-01-01T23:59:59.000Z

402

The Fuzzy Design of the Intelligent System for the Energy-Saving Lamps  

Science Journals Connector (OSTI)

In the paper, a intelligent system was proposed. It consists of variable converter and intelligent controller. Variable reactor which concludes variable reactance converter and power converter has wide applications in the soft starting, speed controlling ... Keywords: fuzzy control, variable reactor, intelligent control, power converter, Energy-Saving Lamps

Youxin Yuan; Kaihua Cui; Yiping Xiao; Tieliang Xu

2008-12-01T23:59:59.000Z

403

Dark matter interacts with variable vacuum energy  

E-Print Network (OSTI)

We investigate a spatially flat Friedmann-Robertson-Walker (FRW) scenario with two interacting components, dark matter and variable vacuum energy (VVE) densities, plus two decoupled components, one is a baryon term while the other behaves as a radiation component. We consider a linear interaction in the derivative dark component density. We apply the $\\chi^2$ method to the observational Hubble data for constraining the cosmological parameters and analyze the amount of dark energy in the radiation era for the model. It turns out that our model fulfills the severe bound of $\\Omega_{x}(z\\simeq 1100)measurements from Planck survey, the future constraints achievable by Euclid and CMBPol experiments, reported for the behavior of the dark energy at early times, and fulfills the stringent bound $\\Omega_{x}(z\\simeq 10^{10})<0.04$ at $2\\sigma$ level in the big-bang nucleosynthesis epoch. We also examine the cosmic age problem at high redshift associated with the old quasar APM 08279+5255 and estimate the age of the universe today.

Iván E. Sánchez G

2014-05-06T23:59:59.000Z

404

Carderock 2-ft Variable Pressure Cavitation Water Tunnel | Open Energy  

Open Energy Info (EERE)

2-ft Variable Pressure Cavitation Water Tunnel 2-ft Variable Pressure Cavitation Water Tunnel Jump to: navigation, search Basic Specifications Facility Name Carderock 2-ft Variable Pressure Cavitation Water Tunnel Overseeing Organization United States Naval Surface Warfare Center Hydrodynamic Testing Facility Type Tunnel Beam(m) 0.6 Depth(m) 0.6 Water Type Freshwater Cost(per day) Contact POC Special Physical Features The 2-Foot Variable Pressure Cavitation Water Tunnel is a vertical plane, closed recirculating, variable-speed, variable-pressure, open jet test section, closed jet test section, and semi-rectangular test section. Towing Capabilities Towing Capabilities None Wavemaking Capabilities Wavemaking Capabilities None Channel/Tunnel/Flume Channel/Tunnel/Flume Yes Velocity(m/s) 17 Recirculating Yes

405

Carderock 3-ft Variable Pressure Cavitation Water Tunnel | Open Energy  

Open Energy Info (EERE)

Variable Pressure Cavitation Water Tunnel Variable Pressure Cavitation Water Tunnel Jump to: navigation, search Basic Specifications Facility Name Carderock 3-ft Variable Pressure Cavitation Water Tunnel Overseeing Organization United States Naval Surface Warfare Center Hydrodynamic Testing Facility Type Tunnel Beam(m) 0.7 Depth(m) 0.7 Water Type Freshwater Cost(per day) Contact POC Special Physical Features The 3-ft Variable Pressure Cavitation Water Tunnel is a vertical plane, closed recirculating with resorber, variable-speed, variable-pressure, two interchangeable circular test sections. Towing Capabilities Towing Capabilities None Wavemaking Capabilities Wavemaking Capabilities None Channel/Tunnel/Flume Channel/Tunnel/Flume Yes Velocity(m/s) 25.8 Recirculating Yes Wind Capabilities Wind Capabilities None

406

Integrating Variable Renewable Energy in Electric Power Markets: Best Practices from International Experience, Summary for Policymakers  

SciTech Connect

Many countries -- reflecting very different geographies, markets, and power systems -- are successfully managing high levels of variable renewable energy on the electric grid, including that from wind and solar energy. This document summarizes policy best practices that energy ministers and other stakeholders can pursue to ensure that electricity markets and power systems can effectively coevolve with increasing penetrations of variable renewable energy. There is no one-size-fits-all approach; each country studied has crafted its own combination of policies, market designs, and system operations to achieve the system reliability and flexibility needed to successfully integrate renewables. Notwithstanding this diversity, the approaches taken by the countries studied all coalesce around five strategic areas: lead public engagement, particularly for new transmission; coordinate and integrate planning; develop rules for market evolution that enable system flexibility; expand access to diverse resources and geographic footprint of operations; and improve system operations. This study also emphatically underscores the value of countries sharing their experiences. The more diverse and robust the experience base from which a country can draw, the more likely that it will be able to implement an appropriate, optimized, and system-wide approach.

Cochran, J.; Bird, L.; Heeter, J.; Arent, D. A.

2012-04-01T23:59:59.000Z

407

E-Print Network 3.0 - automatic identification system Sample...  

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

Automatic2 Fingerprint Identification System (AFIS) in the 1960s. The use... -Finger Penetration Rate and ROC Variability for Automatic Fingerprint Identification Systems", in...

408

Narrow-bandwidth operation and improved beam quality of a semiconductor broad area laser in an improved variable-length external cavity.  

E-Print Network (OSTI)

??We have devised an improved collimation system for a variable-length Littman-Metcalf external cavity diode laser (ECDL), which greatly improves the quality of a broad-area laser… (more)

Coons, Ryan William

2006-01-01T23:59:59.000Z

409

Enabling High Efficiency Clean Combustion with Micro-Variable...  

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

of variable orifice fuel injector are described that will extend the operation maps of early PCCI combustion and enable dual-mode combustion over full operating maps....

410

Cebrian, Just. 2002. Variability and control of carbon consumption ...  

Science Journals Connector (OSTI)

Variability and control of carbon consumption, export, and accumulation in marine communities. Limnol. Oceanogr. 47: 11-22. Web Appendix 1. Net Primary.

2001-09-10T23:59:59.000Z

411

Habitat Variability and Complexity in the Upper San Francisco Estuary  

E-Print Network (OSTI)

can be found in the salinity gradients of Suisun Marsh (diverse habitats and gradients in salinity, depth, and othershowed a strong gradient in salinity and other variables,

Moyle, Peter B; Lund, Jay R.; Bennett, William A; Fleenor, William E.

2010-01-01T23:59:59.000Z

412

Variable Grid Method for Visualizing Uncertainty Associated with...  

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

This Return to Search Variable Grid Method for Visualizing Uncertainty Associated with Spatial Data A decision-making tool for industry,government, academia, and scientists...

413

Variable Temperature Ultra-High Vacuum Scanning Tunneling Microscope...  

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

Vacuum Scanning Tunneling Microscope The Omicron variable temperature ultra-high vacuum (UHV) scanning tunneling microscope (VTSTM) is designed to study the structure of both clean...

414

The Effect of Precipitation on Variability of Low Stratiform...  

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

areal averages of cloud radiative and microphysical properties such as over numerical weather prediction (NWP) or Global Climate Model grid cells. Neglecting this variability...

415

Variable Valve Actuation for Advanced Mode Diesel Combustion...  

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

More Documents & Publications E85 Optimized Engine through Boosting, Spray Optimized GDi, VCR and Variable Valvetrain Ignition Control for HCCI E85 Optimized Engine through...

416

Pitch and torque control of variable speed wind turbines.  

E-Print Network (OSTI)

??In this thesis the torque, speed and pitch angle control of variable speed wind turbine is investigated. In particular, it concentrates on the extraction of… (more)

Kulka, Arkadiusz

2004-01-01T23:59:59.000Z

417

Polymorphic Typing of Variables and References GEOFFREY SMITH  

E-Print Network (OSTI)

Polymorphic Typing of Variables and References GEOFFREY SMITH Florida International University reflect the views of the National Science Foundation. Authors' addresses: G. Smith, School of Computer

Smith, Geoffrey

418

ANOMALOUS LOW STATES AND LONG-TERM VARIABILITY IN THE BLACK HOLE BINARY LMC X-3  

SciTech Connect

Rossi X-ray Timing Explorer observations of the black hole binary LMC X-3 reveal an extended very low X-ray state lasting from 2003 December 13 until 2004 March 18, unprecedented both in terms of its low luminosity (>15 times fainter than ever before seen in this source) and long duration ({approx}3 times longer than a typical low/hard state excursion). During this event little to no source variability is observed on timescales of {approx}hours-weeks, and the X-ray spectrum implies an upper limit of 1.2 Multiplication-Sign 10{sup 35} erg s{sup -1}. Five years later another extended low state occurs, lasting from 2008 December 11 until 2009 June 17. This event lasts nearly twice as long as the first, and while significant variability is observed, the source remains reliably in the low/hard spectral state for the {approx}188 day duration. These episodes share some characteristics with the 'anomalous low states' in the neutron star binary Her X-1. The average period and amplitude of the variability of LMC X-3 have different values between these episodes. We characterize the long-term variability of LMC X-3 before and after the two events using conventional and nonlinear time series analysis methods, and show that, as is the case in Her X-1, the characteristic amplitude of the variability is related to its characteristic timescale. Furthermore, the relation is in the same direction in both systems. This suggests that a similar mechanism gives rise to the long-term variability, which in the case of Her X-1 is reliably modeled with a tilted, warped precessing accretion disk.

Smale, Alan P.; Boyd, Patricia T., E-mail: alan.smale@nasa.gov, E-mail: padi.boyd@nasa.gov [Astrophysics Science Division, NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States)

2012-09-10T23:59:59.000Z

419

Distribution System Research Priorities  

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

Mark McGranaghan Mark McGranaghan EPRI ELECTRICITY DISTRIBUTION SYSTEM WORKSHOP Crystal City, VA September 24, 2012 Distribution System Research Priorities 2 © 2012 Electric Power Research Institute, Inc. All rights reserved. The Power System Roadmaps start with a Vision Future Power System will require new technologies, infrastructure, and control systems 3 © 2012 Electric Power Research Institute, Inc. All rights reserved. R&D Roadmaps - Coordination is Critical Roadmaps are living documents 4 © 2012 Electric Power Research Institute, Inc. All rights reserved. Developing the next generation grid * Industry needs new technologies, communication protocols, and information management methods - More variable generation sources and controllable loads - Aging infrastructure

420

An entanglement rate for continuous variables and its application to a resonant optomechanical multimode setup  

E-Print Network (OSTI)

We introduce a general expression that quantifies the entanglement production rate in continuous variable systems in which entanglement depends on frequency. To exemplify its meaning and potential, we apply it to a four-mode optomechanical setup that enables the simultaneous up- and down-conversion of photons from a drive laser into entangled photon pairs. This setup is efficient in that both the drive and the optomechanical up- and down-conversion can be fully resonant.

Zhi Jiao Deng; Steven J. M. Habraken; Florian Marquardt

2014-06-30T23:59:59.000Z

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


421

Hybrid electromagnetic transient simulation with the state variable representation of HVDC converter plant  

SciTech Connect

The two alternative methods in current use for the transient simulation of HVdc power systems are Electromagnetic Transient Programs and State Variable Analysis. A hybrid algorithm is described in this paper which combines the two methods selecting their best features. The relative performances of conventional and hybrid algorithms are discussed. Simulation results of typical back-to back HVdc link show that the hybrid representation provides more stable, accurate and efficient solutions.

Zavahir, J.M.; Arrillaga, J.; Watson, N.R. (Univ. of Canterbury, Christchurch (New Zealand))

1993-07-01T23:59:59.000Z

422

The Discovery of Aptitude and Achievement Variables  

Science Journals Connector (OSTI)

...stressing knowledge of tools and automobile parts...clocks and operating a steam shovel to designing a...Knowledge of common tools and materiel was apparently...for inductions (seeing systems in arrangements of lines...substantial gains in the assessment of all aspects of personality...

J. P. Guilford

1947-09-26T23:59:59.000Z

423

Explosive transients: a time-variable sky  

Science Journals Connector (OSTI)

......Calculations of the amount of gas involved suggest around...least. The absorbing gas exists before the outburst...physics improves. What drives the explosion? Work on...objects, such as Supernova News, an early warning system...ambient medium provides a natural explanation for afterglow......

David Bersier; Mike Bode; Shiho Kobayashi; Carole Mundell; Iain Steele

2011-02-01T23:59:59.000Z

424

Mass Market Demand Response and Variable Generation Integration Issues: A Scoping Study  

SciTech Connect

This scoping study focuses on the policy issues inherent in the claims made by some Smart Grid proponents that the demand response potential of mass market customers which is enabled by widespread implementation of Advanced Metering Infrastructure (AMI) through the Smart Grid could be the “silver bullet” for mitigating variable generation integration issues. In terms of approach, we will: identify key issues associated with integrating large amounts of variable generation into the bulk power system; identify demand response opportunities made more readily available to mass market customers through widespread deployment of AMI systems and how they can affect the bulk power system; assess the extent to which these mass market Demand Response (DR) opportunities can mitigate Variable Generation (VG) integration issues in the near-term and what electricity market structures and regulatory practices could be changed to further expand the ability for DR to mitigate VG integration issues over the long term; and provide a qualitative comparison of DR and other approaches to mitigate VG integration issues.

Cappers, Peter; Mills, Andrew; Goldman, Charles; Wiser, Ryan; Eto, Joseph H.

2011-09-10T23:59:59.000Z

425

Variable current speed controller for eddy current motors  

DOE Patents (OSTI)

A speed control system for eddy current motors is provided in which the current to the motor from a constant frequency power source is varied by comparing the actual motor speed signal with a setpoint speed signal to control the motor speed according to the selected setpoint speed. A three-phase variable voltage autotransformer is provided for controlling the voltage from a three-phase power supply. A corresponding plurality of current control resistors is provided in series with each phase of the autotransformer output connected to inputs of a three-phase motor. Each resistor is connected in parallel with a set of normally closed contacts of plurality of relays which are operated by control logic. A logic circuit compares the selected speed with the actual motor speed obtained from a digital tachometer monitoring the motor spindle speed and operated the relays to add or substract resistance equally in each phase of the motor input to vary the motor current to control the motor at the selected speed.

Gerth, H.L.; Bailey, J.M.; Casstevens, J.M.; Dixon, J.H.; Griffith, B.O.; Igou, R.E.

1982-03-12T23:59:59.000Z

426

A CURRENT CONTROLLED VARIABLE DELAY SUPERCONDUCTING TRANSMISSION LINE  

E-Print Network (OSTI)

I I I I 1388 A CURRENT CONTROLLED VARIABLE DELAY SUPERCONDUCTING TRANSMISSION LINE S. M. Anlage, H line. The device makes use of the change in kinetic inductance of a superconducting transmission line, fabrication of transmission lines with such films provides the means for constructing a continuously variable

Anlage, Steven

427

Control of Variable Geometry Turbocharged Diesel Engines for Reduced Emissions  

E-Print Network (OSTI)

in a Diesel engine equipped with a variable geometry tur- bocharger (VGT) and an external exhaust gas INJECTION EXHAUST MANIFOLD EGR VALVE EGR COOLER AIR EXHAUST Figure 1: Schematic representation of the DieselControl of Variable Geometry Turbocharged Diesel Engines for Reduced Emissions A.G. Stefanopoulouz

Stefanopoulou, Anna

428

Rank/sparsity minimization and latent variable graphical model selection  

E-Print Network (OSTI)

Rank/sparsity minimization and latent variable graphical model selection Pablo A. Parrilo · Complication: latent variables · Rank/sparsity decomposition, and generalizations · Convex optimization cond. on other vars. 1 3 2 4 Sparse Low-rank Concentration matrix #12;Proposal for modeling · Decompose

Parrilo, Pablo A.

429

Applications of Geostatistics What is different about environmental variables  

E-Print Network (OSTI)

in spoil/tailings/surroundings ­ Similar to modeling common in mining 3. Air ­ Similar to underground water techniques from machine learning · Examples MinE 422: Modeling Environmental Variables Resources: -Some there Types of variables of interest · Contaminants/pollution · Radiation · Precipitation · Temperature

Boisvert, Jeff

430

Optimal Algorithms for Generating Discrete Random Variables with Changing Distributions  

E-Print Network (OSTI)

Optimal Algorithms for Generating Discrete Random Variables with Changing Distributions T. Hagerup arithmetic and the floor function, 3. generating a uniformly distributed real number between 0 and 1 K. Mehlhorn I. Munro Abstract We give optimal algorithms for generating discrete random variables

Mehlhorn, Kurt

431

Weaving Variability into Domain Metamodels Brice Morin1  

E-Print Network (OSTI)

greater learning curve for DSMLs stakeholders and a significant overhead in product line engineering. We should be designed, validated, implemented rapidly, at a low cost. The Soft- ware Product Line [1] (SPL variability capabilities. In particular we detail how variability is woven and how to perform product line

Paris-Sud XI, Université de

432

Instrumental Variables and the Search for Identification: From Supply and  

E-Print Network (OSTI)

and demand for flaxseed, the source of linseed oil.2 Wright noted the difficulty of obtaining estimatesInstrumental Variables and the Search for Identification: From Supply and Demand to Natural variables involved attempts to estimate demand and supply curves.1 Economists such as P.G. Wright, Henry

Ahmad, Sajjad

433

Interannual variability of photosynthesis across Africa and its attribution  

E-Print Network (OSTI)

Interannual variability of photosynthesis across Africa and its attribution Christopher A. Williams of photosynthesis across the African continent during the period 1982�2003. Acute soil water stress emerges as the primary factor driving interannual variability of photosynthesis for most of Africa. Southern savannas

Collett Jr., Jeffrey L.

434

Glossary | Building Energy Codes Program  

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

Vapor Retarder Vapor Retarder A component that retards water vapor diffusion but does not totally prevent its transmission. Vapor retarder material is usually a thin sheet or coating. However, a construction of several materials, some perhaps of substantial thickness, could also constitute a vapor retarder system. Variable Air Volume (VAV) HVAC system that controls the dry-bulb temperature within a space by varying the volumetric flow of heated or cooled supply air to the space. Variable Frequency Drive Changes the speed of the motor by changing the voltage and frequency of the electricity supplied to the motor based upon system requirements. Vent Damper A device intended for installation in the venting system of an individual, automatically operated, fossil-fuel-fired appliance in the outlet or

435

On the combination of variables in empirical scalings  

SciTech Connect

A scaling serves to determine a certain characteristic as a function of a set of variables. It is usually represented in a power-law form in which a constant factor and exponents are the scaling parameters. If there is no theoretical basis to define the values of the scaling parameters, they are determined empirically by fitting them to a certain database using the ordinary least squares regression. It was proposed for various purposes to replace individual primary variables with a combination of these variables in a power-law form when determining the scaling parameters. It is shown that the standard procedure for constructing an empirical scaling in new combined variables gives a scaling equivalent to the primary one. Without any additional modifications in the procedure for determining the scaling parameters, this way of combining the variables seems to be fruitless.

Chudnovskiy, A. N. [Russian Research Centre Kurchatov Institute, Nuclear Fusion Institute (Russian Federation)

2006-04-15T23:59:59.000Z

436

The Deep Lens Survey Transient Search I Short Timescale and Astrometric Variability  

E-Print Network (OSTI)

We report on the methodology and first results from the Deep Lens Survey transient search. We utilize image subtraction on survey data to yield all sources of optical variability down to 24th magnitude. Images are analyzed immediately after acquisition, at the telescope and in near-real time, to allow for followup in the case of time-critical events. All classes of transients are posted to the web upon detection. Our observing strategy allows sensitivity to variability over several decades in timescale. The DLS is the first survey to classify and report all types of photometric and astrometric variability detected, including solar system objects, variable stars, supernovae, and short timescale phenomena. Three unusual optical transient events were detected, flaring on thousand-second timescales. All three events were seen in the B passband, suggesting blue color indices for the phenomena. One event (OT 20020115) is determined to be from a flaring Galactic dwarf star of spectral type dM4. From the remaining tw...

Becker, A C; Boeshaar, P C; Clocchiatti, A; Dell'Antonio, I P; Frail, D A; Halpern, J; Margoniner, V E; Norman, D; Tyson, J A; Schommer, R A

2004-01-01T23:59:59.000Z

437

A Deep Catalog of Variable Stars in a 0.66deg^2 Lupus Field  

E-Print Network (OSTI)

We have conducted a wide-field photometric survey in a single 52'x52' field towards the Lupus Galactic Plane in an effort to detect transiting Hot Jupiter planets. The planet Lupus-TR-3b was identified from this work. The dataset also led to the detection of 494 field variables, all of which are new discoveries. This paper presents an overview of the project, along with the total catalog of variables, which comprises 190 eclipsing binaries (of contact, semi-contact and detached configurations), 51 miscellaneous pulsators of various types, 237 long period variables (P>=2d), 11 delta Scuti stars, 4 field RR Lyrae (3 disk and 1 halo) and 1 irregular variable. Our survey provides a complete catalog of W UMa eclipsing binaries in the field to V=18.8, which display a Gaussian period distribution of 0.277+/-0.036d. Several binary systems are likely composed of equal mass M-dwarf components and others display evidence of mass transfer. We find 17 candidate blue stragglers and one binary that has the shortest period known, 0.2009d (V=20.9). The frequency of eclipsing binaries (all types) is found to be 1.7+/-0.4x10^{-3} per star, substantially higher (by a factor of 3-10) than previously determined in the haloes of the globular clusters 47 Tuc and omega Cen. This indicates that cluster dynamics aids mass segregation and binary destruction.

David T. F. Weldrake; Daniel D. R. Bayliss

2007-11-29T23:59:59.000Z

438

Atomic filtering for hybrid continuous-variable/discrete-variable quantum optics  

E-Print Network (OSTI)

We demonstrate atomic filtering of frequency-degenerate photon pairs from a sub-threshold optical parametric oscillator (OPO). The filter, a modified Faraday anomalous dispersion optical filter (FADOF), achieves 70% peak transmission simultaneous with 57 dB out-of-band rejection and a 445 MHz transmission bandwidth. When applied to the OPO output, only the degenerate mode, containing one-mode squeezed vacuum, falls in the filter pass-band; all other modes are strongly suppressed. The high transmission preserves non-classical continuous-variable features, e.g. squeezing or non-gaussianity, while the high spectral purity allows reliable discrete-variable detection and heralding. Correlation and atomic absorption measurements indicate a spectral purity of 96% for the individual photons, and 98% for the photon pairs. These capabilities will enable generation of atom-resonant hybrid states, e.g. "Schr\\"odinger kittens" obtained by photon subtraction from squeezed vacuum, making these exotic states available for quantum networking and atomic quantum metrology applications.

Joanna A. Zieli?ska; Federica A. Beduini; Vito Giovanni Lucivero; Morgan W. Mitchell

2014-09-04T23:59:59.000Z

439

Tripartite nonlocality and continuous-variable entanglement in thermal states of trapped ions  

SciTech Connect

We study a system of three trapped ions in an anisotropic bidimensional trap. By focusing on the transverse modes of the ions, we show that the mutual ion-ion Coulomb interactions set entanglement of a genuine tripartite nature, to some extent persistent to the thermal nature of the vibronic modes. We tackle this issue by addressing a nonlocality test in the phase space of the ionic system and quantifying the genuine residual tripartite entanglement in the continuous variable state of the transverse modes.

Li Jie; Paternostro, Mauro [School of Mathematics and Physics, Queen's University, Belfast BT7 1NN (United Kingdom); Fogarty, Thomas; Busch, Thomas [Physics Department, University College Cork, Cork (Ireland); Cormick, Cecilia [Theoretische Physik, Universitaet des Saarlandes, D-66041 Saarbruecken (Germany); Goold, John [Physics Department, University College Cork, Cork (Ireland); Clarendon Laboratory, University of Oxford (United Kingdom)

2011-08-15T23:59:59.000Z

440

SPECTROSCOPY OF NEW AND POORLY KNOWN CATACLYSMIC VARIABLES IN THE KEPLER FIELD  

SciTech Connect

The NASA Kepler mission has been in science operation since 2009 May and is providing high precision, high cadence light curves of over 150,000 targets. Prior to launch, nine cataclysmic variables were known to lie within Kepler's field of view. We present spectroscopy for seven systems, four of which were newly discovered since launch. All of the stars presented herein have been observed by, or are currently being observed by, the Kepler space telescope. Three historic systems and one new candidate could not be detected at their sky position and two candidates are called into question as to their true identity.

Howell, Steve B.; Still, Martin [NASA Ames Research Center, Moffett Field, CA 94035 (United States); Everett, Mark E. [National Optical Astronomy Observatory, 950 North Cherry Avenue, Tucson, AZ 85719 (United States); Seebode, Sally A. [San Mateo High School, San Mateo, CA 94401 (United States); Szkody, Paula [Astronomy Department, University of Washington, Seattle, WA 98195 (United States); Wood, Matt [Physics and Astronomy Department, Texas A and M University-Commerce, Commerce, TX 75429 (United States); Ramsay, Gavin [Armagh Observatory, College Hill, Armagh BT61 9DG (United Kingdom); Cannizzo, John [CRESST and Astroparticle Physics Laboratory, NASA/GSFC, Greenbelt, MD 20771 (United States); Smale, Alan [NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States)

2013-04-15T23:59:59.000Z

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


441

Solar Reserve Methodology for Renewable Energy Integration Studies Based on Sub-Hourly Variability Analysis: Preprint  

SciTech Connect

Increasing penetrations of wind a solar energy are raising concerns among electric system operators because of the variability and uncertainty associated with power sources. Previous work focused on the quantification of reserves for systems with wind power. This paper presents a new methodology that allows the determination of necessary reserves for high penetrations of photovoltaic (PV) power and compares it to the wind-based methodology. The solar reserve methodology is applied to Phase 2 of the Western Wind and Solar Integration Study. A summary of the results is included.

Ibanez, E.; Brinkman, G.; Hummon, M.; Lew, D.

2012-08-01T23:59:59.000Z

442

Load sensing system  

DOE Patents (OSTI)

A load sensing system inexpensively monitors the weight and temperature of stored nuclear material for long periods of time in widely variable environments. The system can include an electrostatic load cell that encodes weight and temperature into a digital signal which is sent to a remote monitor via a coaxial cable. The same cable is used to supply the load cell with power. When multiple load cells are used, vast

Sohns, Carl W. (Oak Ridge, TN); Nodine, Robert N. (Knoxville, TN); Wallace, Steven Allen (Knoxville, TN)

1999-01-01T23:59:59.000Z

443

Metropolis Importance Sampling for Rugged Dynamical Variables  

E-Print Network (OSTI)

A funnel transformation is introduced, which acts recursively from higher towards lower temperatures. It biases the a-priori probabilities of a canonical or generalized ensemble Metropolis simulation, so that they zoom in on the global energy minimum, if a funnel exists indeed. A first, crude approximation to the full transformation, called rugged Metropolis one (RM$_1$), is tested for Met-Enkephalin. At 300$ $K the computational gain is a factor of two and, due to its simplicity, RM$_1$ is well suited to replace the conventional Metropolis updating for these kind of systems.

Bernd A. Berg

2002-09-17T23:59:59.000Z

444

Variable g value of transparent façade collectors  

Science Journals Connector (OSTI)

Transparent solar thermal collectors (TSTC) represent a new development. An adequate model is needed to predict their performance. This paper presents a collector model with an advanced calculation of the transmission of diffuse radiation and a connection to the building which allows analysis of the collector gains and of the g value, also called “solar factor”, “solar heat gain coefficient (SHGC)” or “total solar energy transmittance”. The model is implemented as a TRNSYS Type and a coupled simulation between a collector and a room is presented for different façade constructions. Façade areas with glazing and venetian blinds are simulated with a second new TRNSYS Type which introduces high modelling accuracy for façades with solar control systems. An HVAC system is presented together with a first estimate of possible reductions of primary energy. It indicates primary energy savings of about 30% by replacing opaque walls with transparent collectors. The g values prove to depend not only on the irradiation, but also on the operation of the solar collectors and vary e.g. between 0.04 and 0.21. Detailed modelling of active façades like TSTC is therefore essential for accurate predictions of the collector gain, the heating and cooling loads and the thermal comfort.

Christoph Maurer; Tilmann E. Kuhn

2012-01-01T23:59:59.000Z

445

Fuzzy Logic for Biological and Agricultural Systems  

Science Journals Connector (OSTI)

Fuzzy logic is a powerful concept for handling non-linear, time-varying, adaptive systems. It permits the use of linguistic values of variables and imprecise relationships for modeling system behavior. The paper presents an overview of fuzzy logic ... Keywords: agricultural systems, biological systems, fuzzy logic, modeling

Brian Center; Brahm P. Verma

1998-02-01T23:59:59.000Z

446

Abstract Efficiency issues of variable-capacitance micromotors are discussed in context of combined drive and motor  

E-Print Network (OSTI)

motors, electric drives, efficiency I. INTRODUCTION An active area of research for commercial of combined drive and motor interaction. It is shown that variable-capacitance motors ideally have nearly, the drive system consisting of both the motor and electronics is not ideal when considering different

Chapman, Patrick

447

A Monitoring Campaign for Luhman 16AB. I. Detection of Resolved Near-Infrared Spectroscopic Variability  

E-Print Network (OSTI)

[abbreviated] We report resolved near-infrared spectroscopic monitoring of the nearby L dwarf/T dwarf binary WISE J104915.57-531906.1AB (Luhman 16AB), as part of a broader campaign to characterize the spectral energy distribution and temporal variability of this system. A continuous 45-minute sequence of low-resolution IRTF/SpeX data spanning 0.8-2.4 micron were obtained, concurrent with combined-light optical photometry with ESO/TRAPPIST. Our spectral observations confirm the flux reversal of this binary, and we detect a wavelength-dependent decline in the relative spectral fluxes of the two components coincident with a decline in the combined-light optical brightness of the system over the course of the observation. These data are successfully modeled as a combination of brightness and color variability in the T0.5 Luhman 16B, consistent cloud variations; and no significant variability in L7.5 Luhman 16A. We estimate a peak-to-peak amplitude of 13.5% at 1.25 micron over the full lightcurve. Using a two-spot...

Burgasser, Adam J; Faherty, Jacqueline K; Radigan, Jacqueline; J., Amaury H M; Plavchan, Peter; Street, Rachel; Jehin, E; Delrez, L; Opitom, C

2014-01-01T23:59:59.000Z

448

Controls on morphological variability and role of stream power distribution pattern, Yamuna River, western India  

Science Journals Connector (OSTI)

Abstract Understanding the controls on the morphological variability of river systems constitutes one of the fundamental questions in geomorphic investigation. Channel morphology is an important indicator of river processes and is of significance for mapping the hydrology-ecologic connectivity in a river system and for predicting the future trajectory of river health in response to external forcings. This paper documents the spatial morphological variability and its natural and anthropogenic controls for the Yamuna River, a major tributary of the Ganga River, India. The Yamuna River runs through a major urban centre i.e. Delhi National Capital Region. The Yamuna River was divided into eight geomorphically distinct reaches on the basis of the assemblages of geomorphic units and the association of landscape, valley and floodplain settings. The morphological variability was analysed through stream power distribution and sediment load data at various stations. Stream power distribution of the Yamuna River basin is characterised by a non-linear pattern that was used to distinguish (a) high energy ‘natural’ upstream reaches, (b) ‘anthropogenically altered’, low energy middle stream reaches, and (c) ‘rejuvenated’ downstream reaches again with higher stream power. The relationship between stream power and channel morphology in these reaches was integrated with sediment load data to define the maximum flow efficiency (MFE) as the threshold for geomorphic transition. This analysis supports the continuity of river processes and the significance of a holistic, basin-scale approach rather than isolated local scale analysis in river studies.

Nupur Bawa; Vikrant Jain; Shashank Shekhar; Niraj Kumar; Vikas Jyani

2014-01-01T23:59:59.000Z

449

Managing solar-PV variability with geographical dispersion: An Ontario (Canada) case-study  

Science Journals Connector (OSTI)

Abstract The purpose of this article is to determine whether the geographic dispersion of solar-photovoltaic panels reduces variability in energy production. Following this, three questions are posed: 1) If geographic dispersion reduces variability, how dispersed should the panels be?; 2) What happens during peak price periods?; and 3) How are these insights affected by consideration of system-wide demand? Using measured and modelled weather data on an hourly basis from 16 locations across Ontario (Canada), hourly energy production figures for 1000 kW of solar-photovoltaic panels are generated for 2003, 2004, and 2005. Geographical dispersion of panels across multiple locations (as compared to the deployment of all panels in one location, namely, Toronto, Ontario) leads to, in particular instances, energy production profiles that have lower variability, greater total energy production, and a higher correlation value with the Ontario-wide system. Further research is needed both to isolate particularly-advantageous combinations and to broaden the investigation to consider alternative performance metrics, additional analytical techniques and land-use implications.

Ian H. Rowlands; Briana Paige Kemery; Ian Beausoleil-Morrison

2014-01-01T23:59:59.000Z

450

ENSEMBLE VARIABILITY OF NEAR-INFRARED-SELECTED ACTIVE GALACTIC NUCLEI  

SciTech Connect

We present the properties of the ensemble variability V for nearly 5000 near-infrared active galactic nuclei (AGNs) selected from the catalog of Quasars and Active Galactic Nuclei (13th Edition) and the SDSS-DR7 quasar catalog. From three near-infrared point source catalogs, namely, Two Micron All Sky Survey (2MASS), Deep Near Infrared Survey (DENIS), and UKIDSS/LAS catalogs, we extract 2MASS-DENIS and 2MASS-UKIDSS counterparts for cataloged AGNs by cross-identification between catalogs. We further select variable AGNs based on an optimal criterion for selecting the variable sources. The sample objects are divided into subsets according to whether near-infrared light originates by optical emission or by near-infrared emission in the rest frame; and we examine the correlations of the ensemble variability with the rest-frame wavelength, redshift, luminosity, and rest-frame time lag. In addition, we also examine the correlations of variability amplitude with optical variability, radio intensity, and radio-to-optical flux ratio. The rest-frame optical variability of our samples shows negative correlations with luminosity and positive correlations with rest-frame time lag (i.e., the structure function, SF), and this result is consistent with previous analyses. However, no well-known negative correlation exists between the rest-frame wavelength and optical variability. This inconsistency might be due to a biased sampling of high-redshift AGNs. Near-infrared variability in the rest frame is anticorrelated with the rest-frame wavelength, which is consistent with previous suggestions. However, correlations of near-infrared variability with luminosity and rest-frame time lag are the opposite of these correlations of the optical variability; that is, the near-infrared variability is positively correlated with luminosity but negatively correlated with the rest-frame time lag. Because these trends are qualitatively consistent with the properties of radio-loud quasars reported by some previous studies, most of our sample objects are probably radio-loud quasars. Finally, we also discuss the negative correlations seen in the near-infrared SFs.

Kouzuma, S. [School of International Liberal Studies, Chukyo University, Toyota 470-0393 (Japan); Yamaoka, H., E-mail: skouzuma@lets.chukyo-u.ac.jp, E-mail: yamaoka@phys.kyushu-u.ac.jp [Department of Physics, Kyushu University, Fukuoka 812-8581 (Japan)

2012-03-01T23:59:59.000Z

451

Parameters and variables appearing in repository-siting models  

SciTech Connect

Included in this report is a summary of data characterizing the parameters and variables appearing in repository siting models. These data cover the processes of saturates flow, unsaturated flow, surface water flow, geochemistry, heat transport, solute transport, and geomechanical response. Definitions and ranges of values are provided for equation parameters, source terms, dependent variables, boundary conditions, and initial conditions for the equations that are solved in the repository siting models. The data were compiled to help guide the selection of values of parameters and variables to be used in benchmark problems.

Mercer, J.W.; Thomas, S.D.; Ross, B.

1982-12-01T23:59:59.000Z

452

Distinguishing the effects of internal and forced atmospheric variability in climate networks  

E-Print Network (OSTI)

The fact that the Earth climate is a highly complex dynamical system is well-known. In the last few decades a lot of effort has been focused on understanding how climate phenomena in one geographical region affects the climate of other regions. Complex networks are a powerful framework for identifying climate interdependencies. To further exploit the knowledge of the links uncovered via the network analysis (for, e.g., improvements in prediction), a good understanding of the physical mechanisms underlying these links is required. Here we focus in understanding the role of atmospheric variability, and construct climate networks representing internal and forced variability. In the connectivity of these networks we assess the influence of two main indices, NINO3.4 and the North Atlantic Oscillation (NAO), by calculating the networks from time-series where these indices were linearly removed. We find that the connectivity of the forced variability network is heavily affected by ``El Ni\\~no'': removing the NINO3.4 index yields a general loss of connectivity; even teleconnections between regions far away from the equatorial Pacific ocean are lost, suggesting that these regions are not directly linked, but rather, are indirectly interconnected via ``El Ni\\~no'', particularly on interannual time scales. On the contrary, in the internal variability network (independent of sea surface temperature forcing) we find that the links are significantly affected by NAO with a maximum in intra-annual time scales. While the strongest non-local links found are those forced by the ocean, we show that there are also strong teleconnections due to internal atmospheric variability.

J. Ignacio Deza; Cristina Masoller; Marcelo Barreiro

2013-11-13T23:59:59.000Z

453

Cold Air Distribution in Office Buildings: Technology Assessment for California  

E-Print Network (OSTI)

accurate control of supply air volume and temperature willof a control strategy to reset supply air temperature at thecontrol strategies and more efficient motors and fans; (b) System-powered induction boxes; and (c) Direct supply of low temperature

Bauman, F.S.

2008-01-01T23:59:59.000Z

454

Extremes in Chaotic Dynamical Systems  

E-Print Network (OSTI)

Extremes in Chaotic Dynamical Systems Valerio Lucarini valerio.lucarini@uni-hamburg.de D. Faranda Vortragsthema Datum #12;1. Introduction 2. Classical Theory: Extreme Values for i.i.d. Variables 3. Extreme Values in Dynamical Systems: Theoretical Background 4. Numerical Algorithms for studying Extremes 5

455

Low Dose Radiation Research Program: A Variable-Energy Soft X-Ray  

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

A Variable-Energy Soft X-Ray Microprobe to Investigate Mechanisms of A Variable-Energy Soft X-Ray Microprobe to Investigate Mechanisms of the Radiation-Induced Bystander Effect. Authors: Melvyn Folkard, Borivoj Vojnovic, Giuseppe Schettino, Kirk Atkinson, Kevin M Prise, Barry D Michael Institutions: Gray Cancer Institute, PO BO Box100, Mount Vernon Hospital, Northwood, HA6 2JR, UK The Gray Cancer Institute (GCI) has pioneered the use of X-ray focussing techniques to develop systems for micro-irradiating individual cells and sub-cellular targets. Our prototype X-ray microprobe was developed alongside our existing charged-particle microbeam to address problems specific to low LET radiations, or where very precise targeting accuracy and dose delivery are required. This facility was optimised for focusing 278 eV CK X-rays; however there are a number of reasons for extending the

456

Unifying parameter estimation and the Deutsch-Jozsa algorithm for continuous variables  

SciTech Connect

We reveal a close relationship between quantum metrology and the Deutsch-Jozsa algorithm on continuous-variable quantum systems. We develop a general procedure, characterized by two parameters, that unifies parameter estimation and the Deutsch-Jozsa algorithm. Depending on which parameter we keep constant, the procedure implements either the parameter-estimation protocol or the Deutsch-Jozsa algorithm. The parameter-estimation part of the procedure attains the Heisenberg limit and is therefore optimal. Due to the use of approximate normalizable continuous-variable eigenstates, the Deutsch-Jozsa algorithm is probabilistic. The procedure estimates a value of an unknown parameter and solves the Deutsch-Jozsa problem without the use of any entanglement.

Zwierz, Marcin; Perez-Delgado, Carlos A.; Kok, Pieter [Department of Physics and Astronomy, University of Sheffield, Hounsfield Road, Sheffield S3 7RH (United Kingdom)

2010-10-15T23:59:59.000Z

457

Analysis of Cloud Variability and Sampling Errors in Surface and Satellite Mesurements  

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

Analysis of Cloud Variability and Sampling Errors in Analysis of Cloud Variability and Sampling Errors in Surface and Satellite Measurements Z. Li, M. C. Cribb, and F.-L. Chang Earth System Science Interdisciplinary Center University of Maryland College Park, Maryland A. P. Trishchenko and Y. Luo Canada Centre for Remote Sensing Ottawa, Ontario, Canada Introduction Radiation measurements have been widely employed for evaluating cloud parameterization schemes and model simulation results. As the most comprehensive program aiming to improve cloud parameteri- zation schemes, the Atmospheric Radiation Measurement (ARM) Program has an essential goal to make observations on the scale of a general circulation model gridbox, so as to define the physics underlying some of the important parameterizations in the general circulation models used in climate change

458

Adaptation to Climate Variability and Change: A Guidance Manual for  

Open Energy Info (EERE)

Adaptation to Climate Variability and Change: A Guidance Manual for Adaptation to Climate Variability and Change: A Guidance Manual for Development Planning Jump to: navigation, search Tool Summary LAUNCH TOOL Name: Adaptation to Climate Variability and Change: A Guidance Manual for Development Planning Agency/Company /Organization: United States Agency for International Development Sector: Climate, Energy, Land, Water Topics: Adaptation Resource Type: Guide/manual Website: pdf.usaid.gov/pdf_docs/PNADJ990.pdf References: Adaptation to Climate Variability and Change: A Guidance Manual for Development Planning[1] "This Adaptation Guidance Manual is the first of several tools we are developing to assist planners and stakeholders as they cope with a changing climate. As we work with Missions to apply the methods described here, we

459

The Variable Vector Countermeasure Suit for space habitation and exploration  

E-Print Network (OSTI)

The Variable Vector Countermeasure Suit (V2Suit) is a countermeasure suit for sensorimotor adaptation and musculoskeletal deconditioning in microgravity. The V2suit will consist of modules containing arrays of control ...

Vasquez, Rebecca (Rebecca Ann)

2014-01-01T23:59:59.000Z

460

Variability of the Australian Monsoon and Precipitation Trends at Darwin  

Science Journals Connector (OSTI)

An atmospheric classification for northwestern Australia is used to define periods of monsoon activity and investigate the interannual and intraseasonal variability of the Australian monsoon, as well as long-term precipitation trends at Darwin. ...

Stuart Evans; Roger Marchand; Thomas Ackerman

2014-11-01T23:59:59.000Z

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


461

Understanding Recent Eastern Horn of Africa Rainfall Variability and Change  

Science Journals Connector (OSTI)

Observations and sea surface temperature (SST)-forced ECHAM5 simulations are examined to study the seasonal cycle of eastern Africa rainfall and its SST sensitivity during 1979–2012, focusing on interannual variability and trends. The eastern Horn ...

Brant Liebmann; Martin P. Hoerling; Chris Funk; Ileana Bladé; Randall M. Dole; Dave Allured; Xiaowei Quan; Philip Pegion; Jon K. Eischeid

2014-12-01T23:59:59.000Z

462

Stochastic Estimation of Multi-Variable Human Ankle Mechanical Impedance  

E-Print Network (OSTI)

This article presents preliminary stochastic estimates of the multi-variable human ankle mechanical impedance. We employed Anklebot, a rehabilitation robot for the ankle, to provide torque perturbations. Time histories of ...

Rastgaar Aagaah, Mohammad

463

Variability of Consumer Impacts from Energy Efficiency Standards  

Science Journals Connector (OSTI)

A typical prospective analysis of the expected impact of energy efficiency standards on consumers is based on average ... been developed to characterize the variability among individual households and to calculat...

James E. McMahon; Xiaomin Liu

2001-01-01T23:59:59.000Z

464

Optimal combined wind power forecasts using exogeneous variables  

E-Print Network (OSTI)

Optimal combined wind power forecasts using exogeneous variables Fannar ¨Orn Thordarson Kongens of the thesis is combined wind power forecasts using informations from meteorological forecasts. Lyngby, January

465

Baroclinic and barotropic annular variability in the Northern Hemisphere  

Science Journals Connector (OSTI)

Large-scale variability in the Northern Hemisphere (NH) circulation can be viewed in the context of three primary types of structures: 1) teleconnection patterns; 2) a barotropic annular mode; and 3) a baroclinic annular mode. The barotropic ...

David W. J. Thompson; Ying Li

466

Are Cataclysmic Variables the Progenitors of Thermonuclear Supernovae?  

Science Journals Connector (OSTI)

In 1973, Whelan and Iben suggested that binary stars, similar in structure to Cataclysmic Variables but not called that by them, were the progenitors of SN Ia’s. Their evidence included the fact that thermonuclear

Sumner Starrfield

2003-01-01T23:59:59.000Z

467

Information criteria for variable selection under sparsity MAARTEN JANSEN  

E-Print Network (OSTI)

Information criteria for variable selection under sparsity MAARTEN JANSEN Departments of Mathematics and Computer Science, Universit´e Libre de Bruxelles B-1050 Brussels, Belgium maarten.jansen

Jansen, Maarten

468

Modeling and Estimating Current Harmonics of Variable Electronic Loads  

E-Print Network (OSTI)

This paper develops a model for relating input current harmonic content to real power consumption for variable electronic loads, specifically for loads' actively controlled inverters energized by an uncontrolled rectification ...

Wichakool, Warit

469

Variability of perceptual multistability: from brain state to individual trait  

Science Journals Connector (OSTI)

...Variability of perceptual multistability: from brain state to individual trait Andreas Kleinschmidt...multistability to demonstrate that the brain constructively interprets sensory input...is related to the context of the current brain state into which the processing of external...

2012-01-01T23:59:59.000Z

470

Reduction of tropical land region precipitation variability via transpiration  

E-Print Network (OSTI)

Tropical rainforests are known to exhibit low intraseasonal precipitation variability compared with oceanic areas with similar mean precipitation in observations and models. In the present study, the potential role of ...

Lee, Jung-Eun

471

Complete Variable-Length \\Fix-Free" Codes David Gillman  

E-Print Network (OSTI)

Complete Variable-Length \\Fix-Free" Codes David Gillman Institute for Mathematics & Its-free codes Supported by NSF grant 9212184-CCR and Darpa contract N00014-92-J-1799. Email address: gillman

Rivest, Ronald L.

472

The pathway of the interdecadal variability in the Pacific Ocean  

Science Journals Connector (OSTI)

Cases of the interdecadal variability in the Pacific Ocean and their evolution were examined in the ... of the interdecadal signals in the central North Pacific. Such signals propagated southwestward, then subduc...

Dongxiao Wang; Zhengyu Liu

2000-09-01T23:59:59.000Z

473

On the decadal and interdecadal variability in the Pacific Ocean  

Science Journals Connector (OSTI)

The Pacific decadal and interdecadal oscillation (PDO) has ... is a long-lived ENSO-like pattern of Pacific climate variability with a period of 10– ... warm (cool) SSTs in the central North Pacific are always ac...

Yang Haijun; Zhang Qiong

2003-01-01T23:59:59.000Z

474

Variable Frequency Drives: Energy Savings and Impact on Motor Performance  

E-Print Network (OSTI)

Variable frequency drives (VFDs) have found widespread application in recent years. VFDs are valued for their potential to save energy and improve processes. Reliability has improved significantly, but there are still pitfalls to be addressed...

Petro, D.

475

Conservation Theory Process Control Using Variable Frequency Drives  

E-Print Network (OSTI)

The purpose of this paper is to outline some of the economic considerations of variable frequency control and to point out possible applications in order to create greater awareness of the options available to the engineer as he develops new...

Myers, N. S.

1980-01-01T23:59:59.000Z

476

Heart rate variability in mice with coronary heart disease  

E-Print Network (OSTI)

Heart rate variability (HRV), the beat-to-beat fluctuation of the heart rate, is a non-invasive test that measures the autonomic regulation of the heart. Assessment of HRV has been shown to predict the risk of mortality ...

Zapanta, Laurence (Laurence F.)

2005-01-01T23:59:59.000Z

477

Renormalization group maps for Ising models in lattice gas variables  

E-Print Network (OSTI)

Real space renormalization group maps, e.g., the majority rule transformation, map Ising type models to Ising type models on a coarser lattice. We show that each coefficient of the renormalized Hamiltonian in the lattice gas variables depends on only a finite number of values of the renormalized Hamiltonian. We introduce a method which computes the values of the renormalized Hamiltonian with high accuracy and so computes the coefficients in the lattice gas variables with high accuracy. For the critical nearest neighbor Ising model on the square lattice with the majority rule transformation, we compute over 1,000 different coefficients in the lattice gas variable representation of the renormalized Hamiltonian and study the decay of these coefficients. We find that they decay exponentially in some sense but with a slow decay rate. We also show that the coefficients in the spin variables are sensitive to the truncation method used to compute them.

Tom Kennedy

2009-05-15T23:59:59.000Z

478

Understanding Space Weather: The Sun as a Variable Star  

Science Journals Connector (OSTI)

The American Meteorological Society has recently adopted space weather as a new core competency. This is the first in a series of papers discussing the multidisciplinary aspects of space weather. This paper concerns the physics behind solar variability, ...

Keith Strong; Julia Saba; Therese Kucera

2012-09-01T23:59:59.000Z

479

Impacts of Variability in Cellulosic Biomass Yields on Energy Security  

Science Journals Connector (OSTI)

Feedstock yield variability needs to be a central part of modeling to ensure that policy makers acknowledge risks to energy supplies and develop strategies or contingency plans that mitigate those risks. ... (1) The Renewable Fuel Standard (RFS) specified in this legislation is a liquid biofuel mandate designed in part to address energy security. ... Without an acknowledgment of variability, there is no basis upon which the emerging biofuel industry and biofuel policy makers can begin to consider and evaluate mitigation options and contingency plans. ...

Kimberley A. Mullins; H. Scott Matthews; W. Michael Griffin; Robert Anex

2014-06-18T23:59:59.000Z

480

A STATE VARIABLE DESCRIPTION OF THE RHIC RF CONTROL LOOPS.  

SciTech Connect

The beam transfer function changes during the RHIC ramp. The response of the RF control loops changes as a result. A state-variable description of the beam and the RF control loops was developed. This description was used to generate a set of feedback matrices that keeps the response of the RF control loops constant during the ramp. This paper describes the state-variable description and its use in determining the K matrices.

SCHULTHEISS,C.; BRENNAN,J.M.

2002-06-02T23:59:59.000Z

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


481

El Nińo Southern Oscillation Variability from 1871-2008  

E-Print Network (OSTI)

EL NI?O SOUTHERN OSCILLATION VARIABILITY FROM 1871-2008 A Dissertation by SULAGNA RAY Submitted to the Office of Graduate Studies of Texas A&M University in partial fulfillment of the requirements for the degree of DOCTOR..., Ping Chang Achim Stoessel Ramalingam Saravanan Head of Department, Piers Chapman December 2011 Major Subject: Oceanography iii ABSTRACT El Ni?o Southern Oscillation Variability from 1871-2008. (December 2011) Sulagna Ray, B.S.; M...

Ray, Sulagna

2012-02-14T23:59:59.000Z

482

A Multichannel, Variable?Threshold, Time?Sequence Recorder  

Science Journals Connector (OSTI)

The analysis and design of a ten?channel variable?threshold time?sequence recorder that uses TTL is presented. Channel?to?channel time resolution is ? 250 nsec and risetime is ? 6 usec for a 2?V p?p signal. Although the recorder is designed to examine the flux?jump phenomenon in large superconducting magnets it has application wherever variable?threshold time?sequencing is required.

Mark L. McKinstry

1973-01-01T23:59:59.000Z

483

Variable Renewable Energy: a Regulatory Roadmap (Fact Sheet)  

SciTech Connect

There is not a one-size-fits-all approach to the regulation of variable renewable energy (VRE), but international experience reveals many approaches that are proving successful. Drawing upon research and experiences from various international contexts, the 21st Century Power Partnership in conjunction with the Clean Energy Solutions Center and Clean Energy Regulators Initiative identified key issues and ideas that have emerged as variable deployment has grown. The Power Partnership research, published in 2014, identified four broad categories of regulatory issues.

Not Available

2014-10-01T23:59:59.000Z

484

Coefficient quantization effects in block state variable digital filters  

E-Print Network (OSTI)

COEFFICIENT QUANTIZATION EFFECTS IN BLOCK STATE VARIABLE DIGITAL FILTERS A Thesis by KAB JOO LEE Submitted to the Office of Graduate Studies of Texas ARM University in partial fulfillment of the requirements for the degree of MASTER... OF SCIENCE August 1991 Major Subject: Electrical Engineering COEFFICIENT QIJANTIZATIOU EFFECTS IN l3LOCI~ STATE VARIABLE DIGITAL FILTERS A Thesis hs IiAB JOO LEE Approved as to style and content by: WVilliam G. )3liss (Chair of Comnaittee) Norman C...

Lee, Kab Joo

2012-06-07T23:59:59.000Z

485

Variability in properties of Salado Mass Concrete  

SciTech Connect

Salado Mass Concrete (SMC) has been developed for use as a seal component in the Waste Isolation Pilot Plant. This concrete is intended to be mixed from pre-bagged materials, have an initial slump of 10 in., and remain pumpable and placeable for two hours after mixing. It is a mass concrete because it will be placed in monoliths large enough that the heat generated during cement hydration has the potential to cause thermal expansion and subsequent cracking, a phenomenon to avoid in the seal system. This report describes effects on concrete properties of changes in ratio of water to cement, batch size, and variations in characteristics of different lots of individual components of the concrete. The research demonstrates that the concrete can be prepared from laboratory-batched or pre-bagged dry materials in batches from 1.5 ft{sup 3} to 5.0 yd{sup 3}, with no chemical admixtures other than the sodium chloride added to improve bonding with the host rock, at a water-to-cement ratio ranging from 0.36 to 0.42. All batches prepared according to established procedures had adequate workability for at least 1.5 hours, and achieved or exceeded the target compressive strength of 4500 psi at 180 days after casting. Portland cement and fly ash from different lots or sources did not have a measurable effect on concrete properties, but variations in a shrinkage-compensating cement used as a component of the concrete did appear to affect workability. A low initial temperature and the water-reducing and set-retarding functions of the salt are critical to meeting target properties.

Wakeley, L.D.; Harrington, P.T. [US Army Engineer Waterways Experiment Station, Vicksburg, MS (United States); Hansen, F.D. [Sandia National Labs., Albuquerque, NM (United States)

1995-08-01T23:59:59.000Z

486

Variable Voltage Substation Electric Fire and Emergency Response  

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

Variable Voltage Substation Electric Fire and Emergency Response My question is from an emergency response perspective. You stated that it took ~ ˝ for electricians to de-energize the electrical components before firefighters were allowed in to fight the fire. This delay causes more damage to equipment and potential propagation of the fire. Is there not a “master” breaker or switch? You’ve brought up a very good point. It gave me a good opportunity to discuss this with our Facilities Department and get a better understanding of the infrastructure upgrade plans. The direct answer to your question is “Yes, but…” Yes, there are “master” breakers and switches, but we can’t control them remotely. SLAC’s AC electrical distribution system at present is manual breakers – we have not installed the infrastructure to remotely control them (except see below). We recently underwent an upgrade to our Master Substation that will allow us to remotely control some high voltage breakers in the future, but we aren’t there yet. We do recognize the value in having this capability (and more importantly, our vulnerability in NOT having it), and have begun the preliminary planning to make this happen. One issue were are working on is cyber security for the power distribution networked infrastructure. Before we install the capability to remotely control the main electrical breakers, we are planning the infrastructure with our Information Technologies organization to ensure we have a robust secure network that is protected from unauthorized access. Once the cyber security issues are addressed and funded, we’re probably 5-10 years out from having remote operation capability due to limited resources to fund and install the infrastructure. Having said the above, we do have the capability of remotely opening the VVS Secondary Main Breakers – the ones that send power to the modulator distribution breakers - from our control room. Those breakers are integral parts of our safety systems in that interlock violation causes the breakers to open and remove power to the klystrons. But everything else is manual only. That remote operation capability would not have helped us in this case, as the VVS Secondary Main Breaker was the one that fried. We needed to open the breaker upstream of the VVS. Thanks for your interest. Let me know if I can provide further information.

487

ASSOCIATING LONG-TERM {gamma}-RAY VARIABILITY WITH THE SUPERORBITAL PERIOD OF LS I +61 Degree-Sign 303  

SciTech Connect

Gamma-ray binaries are stellar systems for which the spectral energy distribution (discounting the thermal stellar emission) peaks at high energies. Detected from radio to TeV gamma rays, the {gamma}-ray binary LS I +61 Degree-Sign 303 is highly variable across all frequencies. One aspect of this system's variability is the modulation of its emission with the timescale set by the {approx}26.4960 day orbital period. Here we show that, during the time of our observations, the {gamma}-ray emission of LS I +61 Degree-Sign 303 also presents a sinusoidal variability consistent with the previously known superorbital period of 1667 days. This modulation is more prominently seen at orbital phases around apastron, whereas it does not introduce a visible change close to periastron. It is also found in the appearance and disappearance of variability at the orbital period in the power spectrum of the data. This behavior could be explained by a quasi-cyclical evolution of the equatorial outflow of the Be companion star, whose features influence the conditions for generating gamma rays. These findings open the possibility to use {gamma}-ray observations to study the outflows of massive stars in eccentric binary systems.

Ackermann, M.; Buehler, R. [Deutsches Elektronen Synchrotron DESY, D-15738 Zeuthen (Germany); Ajello, M. [Space Sciences Laboratory, 7 Gauss Way, University of California, Berkeley, CA 94720-7450 (United States); Ballet, J.; Casandjian, J. M. [Laboratoire AIM, CEA-IRFU/CNRS/Universite Paris Diderot, Service d'Astrophysique, CEA Saclay, F-91191 Gif sur Yvette (France); Barbiellini, G. [Istituto Nazionale di Fisica Nucleare, Sezione di Trieste, I-34127 Trieste (Italy); Bastieri, D.; Buson, S. [Istituto Nazionale di Fisica Nucleare, Sezione di Padova, I-35131 Padova (Italy); Bellazzini, R.; Bregeon, J. [Istituto Nazionale di Fisica Nucleare, Sezione di Pisa, I-56127 Pisa (Italy); Bonamente, E.; Cecchi, C. [Istituto Nazionale di Fisica Nucleare, Sezione di Perugia, I-06123 Perugia (Italy); Brandt, T. J. [NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Brigida, M. [Dipartimento di Fisica ''M. Merlin'' dell'Universita e del Politecnico di Bari, I-70126 Bari (Italy); Bruel, P. [Laboratoire Leprince-Ringuet, Ecole polytechnique, CNRS/IN2P3, F-91128 Palaiseau (France); Caliandro, G. A. [Institute of Space Sciences (IEEE-CSIC), Campus UAB, E-08193 Barcelona (Spain); Cameron, R. A. [W. W. Hansen Experimental Physics Laboratory, Kavli Institute for Particle Astrophysics and Cosmology, Department of Physics and SLAC National Accelerator Laboratory, Stanford University, Stanford, CA 94305 (United States); Caraveo, P. A. [INAF-Istituto di Astrofisica Spaziale e Fisica Cosmica, I-20133 Milano (Italy); Cavazzuti, E. [Agenzia Spaziale Italiana (ASI) Science Data Center, I-00044 Frascati (Roma) (Italy); Chekhtman, A., E-mail: andrea.caliandro@ieec.uab.es, E-mail: hadasch@ieec.uab.es, E-mail: dtorres@ieec.uab.es [Center for Earth Observing and Space Research, College of Science, George Mason University, Fairfax, VA 22030 (United States); and others

2013-08-20T23:59:59.000Z

488

Occupant Response to Window Control Signaling Systems  

E-Print Network (OSTI)

Air Conditioning   Fan coil units, variable refrigerant active cooling via fan coil units and radiant panels, system to perimeter fan coil units, and “open”  mode for 

Ackerly, Katherine

2012-01-01T23:59:59.000Z

489

Effect on energy use and greenhouse microclimate through fan motor control by variable frequency drives  

Science Journals Connector (OSTI)

A comparison was conducted between ON–OFF and variable frequency drive (VFD) systems to control greenhouse ventilation fans. The study aimed to determine the effect of each system on the energy consumption and resulting greenhouse microclimate. The experiments were conducted in a commercial size greenhouse in which pepper was grown. To check the performance of the fan that was controlled by a VFD system, it was installed in a test facility and operated under several rotation speeds. At each speed of rotation, the static pressure on the fan was changed and parameters, such as electricity consumption and air flow rate, were measured. Reducing the fan speed with the VFD system resulted in reductions in the air flow rate through the greenhouse and energy consumption, the latter being much more significant. The study showed that VFD control can reduce electricity consumption compared with ON–OFF operation by an amount that depends on the weather. In the present study, the average energy consumption with the VFD control system over a period of one month, was about 0.64 of that with an ON–OFF system. The average greenhouse daily air temperatures and humidity ratios obtained with each control system between 0700 and 1800 were nearly equal during that month. The results obtained in the greenhouse further show that the VFD system has a greater potential than the ON–OFF to reduce the range of amplitude variations in the air temperature and humidity ratio within the greenhouse.

Meir Teitel; Yun Zhao; Moti Barak; Eli Bar-lev; David Shmuel

2004-01-01T23:59:59.000Z

490

Combined permeable pavement and ground source heat pump systems   

E-Print Network (OSTI)

The PhD thesis focuses on the performance assessment of permeable pavement systems incorporating ground source heat pumps (GSHP). The relatively high variability of temperature in these systems allows for the survival of pathogenic organisms within...

Grabowiecki, Piotr

2010-01-01T23:59:59.000Z

491

Engineering the Interface Between Cellular Chassis and Integrated Biological Systems  

E-Print Network (OSTI)

The engineering of biological systems with predictable behavior is a challenging problem. One reason for this difficulty is that engineered biological systems are embedded within complex and variable host cells. To help ...

Canton, Bartholomew

2005-08-08T23:59:59.000Z

492

Safety equipment list for the light duty utility arm system  

SciTech Connect

The initial issue (Revision 0) of this Safety Equipment List (SEL) for the Light Duty Utility Arm (LDUA) requires an explanation for both its existence and its being what it is. All LDUA documentation leading up to creation of this SEL, and the SEL itself, is predicated on the LDUA only being approved for use in waste tanks designated as Facility Group 3, i.e., it is not approved for use in Facility Group 1 or 2 waste tanks. Facility Group 3 tanks are those in which a spontaneous or induced hydrogen gas release would be small, localized, and would not exceed 25% of the LFL when mixed with the remaining air volume in the dome space; exceeding these parameters is considered unlikely. Thus, from a NFPA flammable gas environment perspective the waste tank interior is not classified as a hazardous location. Furthermore, a hazards identification and evaluation (HNF-SD-WM-HIE-010, REV 0) performed for the LDUA system concluded that the consequences of actual LDUA system postulated accidents in Flammable Gas Facility Group 3 waste tanks would have either NO IMPACT or LOW IMPACT on the offsite public and onsite worker. Therefore, from a flammable gas perspective, there is not a rationale for classifying any of SSCs associated with the LDUA as either Safety Class (SC) or Safety Significant (SS) SSCs, which, by default, categorizes them as General Service (GS) SSCs. It follows then, based on current PHMC procedures (HNF-PRO-704 and HNF-IP-0842, Vol IV, Section 5.2) for SEL creation and content, and from a flammable gas perspective, that an SEL is NOT REQ@D HOWEVER!!! There is both a precedent and a prudency to capture all SSCS, which although GS, contribute to a Defense-In-Depth (DID) approach to the design and use of equipment in potentially flammable gas environments. This Revision 0 of the LDUA SEL has been created to capture these SSCs and they are designated as GS-DID in this document. The specific reasons for doing this are listed.

Barnes, G.A.

1998-03-02T23:59:59.000Z

493

Systems and methods for controlling energy use in a building management system using energy budgets  

DOE Patents (OSTI)

Systems and methods for limiting power consumption by a heating, ventilation, and air conditioning (HVAC) subsystem of a building are shown and described. A feedback controller is used to generate a manipulated variable based on an energy use setpoint and a measured energy use. The manipulated variable may be used for adjusting the operation of an HVAC device.

Wenzel, Michael J; Drees, Kirk H

2014-09-23T23:59:59.000Z

494

IEEE TRANSACTIONS ON INDUSTRY APPLICATIONS, VOL. 40, NO. 2, MARCH/APRIL 2004 565 Modeling and Control of a Variable-Speed  

E-Print Network (OSTI)

. The advantages of the proposed system are reduced harmonic injection to power grid, wide speed operation range. It can be directly applied to wind power generators, small-scale hydroelectric generators, stand Identifier 10.1109/TIA.2004.824504 Fig. 1. Traditional wind power generation systems. (a) Variable

Mi, Chunting "Chris"

495

Control of a 6/4 switched reluctance motor in a variable speed pumping application  

Science Journals Connector (OSTI)

An original variable-speed pumping system was developed through integrating a power converter, switched reluctance motor (SRM), centrifugal pump, and speed control strategy. A customized power converter and speed control strategy were selected, designed, and implemented to regulate the speed of the SRM-pump system. The control strategy to regulate the speed of the SRM consisted of a digital controller made with PI and phase-lead compensators in series and, simultaneously, adjusting the advanced firing angle as a function of the desired motor speed. It was experimentally demonstrated that the inverter-SRM-pump system is a good option to drive a centrifugal pump with a relatively high efficiency at all speeds.

Horacio Vasquez; Joey Parker; Timothy Haskew

2005-01-01T23:59:59.000Z

496

Chapter 8 - Advances in Market Management Solutions for Variable Energy Resources Integration  

Science Journals Connector (OSTI)

Abstract Integration of more and more Variable Energy Resources (VER) into the system has introduced new challenges to grid and market operations. This chapter first provides an overview of wholesale electricity markets and market management systems. The intermittent nature of VER’s increases the need for system ramping capability in real-time balancing market, and causes issues in long term market pricing and resource adequacy. Enhancements are being made in both market design and market analytical tools in terms of managing operational uncertainties introduced by VER integration. The rest of the chapter focuses on two areas of market enhancement. The first one is the idea to establish a ramp market in real-time balancing operation to create the right market incentives for resources to provide enough ramping energy to compensate VER volatility. The second topic is to manage short-term VER uncertainty by applying robust optimization to look-ahead unit commitment.

Xing Wang

2014-01-01T23:59:59.000Z

497

Stabilising the triple inverted pendulum by variable gain linear quadratic regulator  

Science Journals Connector (OSTI)

A variable gain linear quadratic regulator (VGLQR) for multivariable non-linear control systems is designed. This control scheme, which can be viewed as a novel gain scheduling controller, consists of linearising the non-linear system to a family of time-invariant systems about sampling points and using LQR method to obtain optimal feedback gain in every sampling interval. In addition, a fast algorithm based on Schur method for online solving the algebraic Riccati equation is discussed in detail, and a software package, which is used to solve algebraic Riccati equation at each sampling point, is developed during the present research. A triple inverted pendulum is stabilised by using the VGLQR method and the results of simulation and physical experiments are displayed. The results of experiments demonstrate that the present control scheme is of good stability and robustness.

Yongli Zhang; Zhihong Miao; Hongxing Li; Fuzhong Nian

2012-01-01T23:59:59.000Z

498

Predicting scorpion sting incidence in an endemic region using climatological variables*  

E-Print Network (OSTI)

Predicting scorpion sting incidence in an endemic region using climatological variables* G. CHOWELL in Mexico. We analysed the significance of climatological variables to predict the incidence of scorpion seasonal pattern that correlates to climatological variables. An increase in scorpion activity

Chowell, Gerardo

499

A motor drive control system for the Lidar Polarimeter  

E-Print Network (OSTI)

and Quantitative Account Gear-Train Servo Error Types. IV. DC VARIABLE SPEED MOTOR DRIVE DESIGN CONSIDERATIONS AND RFALIZATION. Introduction. 27 29 30 30 34 34 Design Consideration. The DC Power Amplifier. System Operation. Scan System Alignment... and Quantitative Account Gear-Train Servo Error Types. IV. DC VARIABLE SPEED MOTOR DRIVE DESIGN CONSIDERATIONS AND RFALIZATION. Introduction. 27 29 30 30 34 34 Design Consideration. The DC Power Amplifier. System Operation. Scan System Alignment...

Leung, Waiming

2012-06-07T23:59:59.000Z

500

Variable Emission from a Gaseous Disc around a Metal-Polluted White Dwarf  

E-Print Network (OSTI)

We present the discovery of strongly variable emission lines from a gaseous disc around the DA white dwarf SDSS J1617+1620, a star previously found to have an infrared excess indicative of a dusty debris disc formed by the tidal disruption of a rocky planetary body. Time-series spectroscopy obtained during the period 2006-2014 has shown the appearance of strong double-peaked Ca II emission lines in 2008. The lines were weak, at best, during earlier observations, and monotonically faded through the remainder of our monitoring. Our observations represent unambiguous evidence for short-term variability in the debris environment of evolved planetary systems. Possible explanations for this extraordinary variability include the impact onto the dusty disc of either a single small rocky planetesimal, or of material from a highly eccentric debris tail. The increase in flux from the emission lines is sufficient that similar events could be detected in the broadband photometry of ongoing and future large-area time domai...

Wilson, David J; Koester, Detlev; Raddi, Roberto; Breedt, Elmé; Southworth, John; Parsons, Steven G

2014-01-01T23:59:59.000Z