Science.gov

Sample records for allowable operating temperature

  1. Determination of allowable fluid temperature during start-up operation of outlet header under the assumption of constant and temperature-dependent material properties

    NASA Astrophysics Data System (ADS)

    Rząsa, Dariusz; Duda, Piotr

    2013-09-01

    Modern supercritical power plants operate at very high temperatures and pressures. Thus the construction elements are subjected to both high thermal and mechanical loads. As a result high stresses in those components are created. In order to operate safely, it is important to monitor stresses, especially during start-up and shut-down processes. The maximum stresses in the construction elements should not exceed the allowable stresses that are defined according to boiler regulations. It is important to find optimum operating parameters, that can assure safe heating and cooling processes. The optimum parameters define temperature and pressure histories that can keep the highest stresses within allowable limit and reduce operation time as much as possible. In this paper a new numerical method for determining optimum working fluid parameters is presented. In this method, properties of steel can be assumed as constant or temperature dependent. The constant value is taken usually at the average temperature of the operation cycle. For both cases optimal parameters are determined. Based on these parameters start-up operations for both cases are conducted. During entire processes stresses in the heated element are monitored. The results obtained are compared with German boiler regulations - Technische Regeln fur Dampfkessel 301.

  2. 30 CFR 206.160 - Operating allowances.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 30 Mineral Resources 2 2010-07-01 2010-07-01 false Operating allowances. 206.160 Section 206.160 Mineral Resources MINERALS MANAGEMENT SERVICE, DEPARTMENT OF THE INTERIOR MINERALS REVENUE MANAGEMENT PRODUCT VALUATION Federal Gas § 206.160 Operating allowances. Notwithstanding any other provisions...

  3. 30 CFR 1206.160 - Operating allowances.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... Mineral Resources OFFICE OF SURFACE MINING RECLAMATION AND ENFORCEMENT, DEPARTMENT OF THE INTERIOR Natural Resources Revenue PRODUCT VALUATION Federal Gas § 1206.160 Operating allowances. Notwithstanding any other provisions in these regulations, an operating allowance may be used for the purpose of computing...

  4. 30 CFR 1206.160 - Operating allowances.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... Mineral Resources OFFICE OF NATURAL RESOURCES REVENUE, DEPARTMENT OF THE INTERIOR NATURAL RESOURCES REVENUE PRODUCT VALUATION Federal Gas § 1206.160 Operating allowances. Notwithstanding any other provisions in these regulations, an operating allowance may be used for the purpose of computing...

  5. Allowance trading: Market operations and regulatory response

    SciTech Connect

    Bailey, K.A.; South, D.W.; McDermott, K.A.

    1992-12-31

    The use of the SO{sub 2} allowance system as defined by Title IV of the 1990 Clean Air Act Amendments offers utilities greater compliance flexibility than EPA technology standards, State Implementation Plan (SEP) performance standards, or EPA bubble/offset strategies. Traditional methods at best offered the utility the ability to trade emissions between different units at a particular plant. The SO{sub 2} emissions trading system advocated under Title IV will allow a utility to trade emissions across its utility system, and/or trade emissions between utilities to take advantage of interfirm control cost differences. The use of transferable emission allowances offers utilities greater flexibility in the choice of how to control emissions: the choices include fuel switching, flue gas scrubbing, environmental dispatch, repowering, and even the choice not to control emissions [as long as the New Source Performance Standards (NSPS) and Prevention of Significant Deterioration (PSD) requirements are met]. The added flexibility allows utilities to choose the least cost manner of compliance with Title IV requirements. It is hoped (intended) that pollution control cost-minimization by individual utilities will in turn reduce the cost of controlling SO{sub 2} for the electric utility industry in aggregate. In addition, through the use of NO{sub x} emission averaging, the utility would average NO{sub x} emissions from different point sources in order to comply with the prescribed emission standard.

  6. Allowance trading: Market operations and regulatory response

    SciTech Connect

    Bailey, K.A.; South, D.W.; McDermott, K.A.

    1992-01-01

    The use of the SO[sub 2] allowance system as defined by Title IV of the 1990 Clean Air Act Amendments offers utilities greater compliance flexibility than EPA technology standards, State Implementation Plan (SEP) performance standards, or EPA bubble/offset strategies. Traditional methods at best offered the utility the ability to trade emissions between different units at a particular plant. The SO[sub 2] emissions trading system advocated under Title IV will allow a utility to trade emissions across its utility system, and/or trade emissions between utilities to take advantage of interfirm control cost differences. The use of transferable emission allowances offers utilities greater flexibility in the choice of how to control emissions: the choices include fuel switching, flue gas scrubbing, environmental dispatch, repowering, and even the choice not to control emissions [as long as the New Source Performance Standards (NSPS) and Prevention of Significant Deterioration (PSD) requirements are met]. The added flexibility allows utilities to choose the least cost manner of compliance with Title IV requirements. It is hoped (intended) that pollution control cost-minimization by individual utilities will in turn reduce the cost of controlling SO[sub 2] for the electric utility industry in aggregate. In addition, through the use of NO[sub x] emission averaging, the utility would average NO[sub x] emissions from different point sources in order to comply with the prescribed emission standard.

  7. 30 CFR 206.120 - How are operating allowances determined?

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 30 Mineral Resources 2 2010-07-01 2010-07-01 false How are operating allowances determined? 206.120 Section 206.120 Mineral Resources MINERALS MANAGEMENT SERVICE, DEPARTMENT OF THE INTERIOR MINERALS REVENUE MANAGEMENT PRODUCT VALUATION Federal Oil § 206.120 How are operating allowances determined?...

  8. 30 CFR 1206.120 - How are operating allowances determined?

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 30 Mineral Resources 3 2014-07-01 2014-07-01 false How are operating allowances determined? 1206.120 Section 1206.120 Mineral Resources OFFICE OF NATURAL RESOURCES REVENUE, DEPARTMENT OF THE INTERIOR NATURAL RESOURCES REVENUE PRODUCT VALUATION Federal Oil § 1206.120 How are operating allowances...

  9. 30 CFR 1206.120 - How are operating allowances determined?

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 30 Mineral Resources 3 2012-07-01 2012-07-01 false How are operating allowances determined? 1206.120 Section 1206.120 Mineral Resources OFFICE OF NATURAL RESOURCES REVENUE, DEPARTMENT OF THE INTERIOR NATURAL RESOURCES REVENUE PRODUCT VALUATION Federal Oil § 1206.120 How are operating allowances...

  10. 30 CFR 1206.120 - How are operating allowances determined?

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 30 Mineral Resources 3 2013-07-01 2013-07-01 false How are operating allowances determined? 1206.120 Section 1206.120 Mineral Resources OFFICE OF NATURAL RESOURCES REVENUE, DEPARTMENT OF THE INTERIOR NATURAL RESOURCES REVENUE PRODUCT VALUATION Federal Oil § 1206.120 How are operating allowances...

  11. 49 CFR 174.86 - Maximum allowable operating speed.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 2 2012-10-01 2012-10-01 false Maximum allowable operating speed. 174.86 Section 174.86 Transportation Other Regulations Relating to Transportation PIPELINE AND HAZARDOUS MATERIALS SAFETY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION HAZARDOUS MATERIALS REGULATIONS CARRIAGE BY...

  12. 49 CFR 174.86 - Maximum allowable operating speed.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... Handling of Placarded Rail Cars, Transport Vehicles and Freight Containers § 174.86 Maximum allowable operating speed. (a) For molten metals and molten glass shipped in packagings other than those prescribed in...) for shipments by rail. (b) For trains transporting any loaded, placarded tank cars containing...

  13. 49 CFR 174.86 - Maximum allowable operating speed.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... Handling of Placarded Rail Cars, Transport Vehicles and Freight Containers § 174.86 Maximum allowable operating speed. (a) For molten metals and molten glass shipped in packagings other than those prescribed in...) for shipments by rail. (b) For trains transporting any loaded, placarded tank cars containing...

  14. 30 CFR 1206.120 - How are operating allowances determined?

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 30 Mineral Resources 3 2011-07-01 2011-07-01 false How are operating allowances determined? 1206.120 Section 1206.120 Mineral Resources OFFICE OF SURFACE MINING RECLAMATION AND ENFORCEMENT, DEPARTMENT OF THE INTERIOR Natural Resources Revenue PRODUCT VALUATION Federal Oil § 1206.120 How...

  15. Temperature-Operated Valve

    NASA Technical Reports Server (NTRS)

    Morrison, Andrew D.

    1994-01-01

    Bimetallic valve stem positions orifice at end of inner pipe orifice so liquid flows to outlet when temperature lies within small range of preset value. If liquid too cold or too hot, orifices misaligned and liquid returned to source. Such as in shower, valve prevents outflow of dangerously hot or uncomfortably cold water.

  16. A Review & Assessment of Current Operating Conditions Allowable Stresses in ASME Section III Subsection NH

    SciTech Connect

    R. W. Swindeman

    2009-12-14

    The current operating condition allowable stresses provided in ASME Section III, Subsection NH were reviewed for consistency with the criteria used to establish the stress allowables and with the allowable stresses provided in ASME Section II, Part D. It was found that the S{sub o} values in ASME III-NH were consistent with the S values in ASME IID for the five materials of interest. However, it was found that 0.80 S{sub r} was less than S{sub o} for some temperatures for four of the materials. Only values for alloy 800H appeared to be consistent with the criteria on which S{sub o} values are established. With the intent of undertaking a more detailed evaluation of issues related to the allowable stresses in ASME III-NH, the availabilities of databases for the five materials were reviewed and augmented databases were assembled.

  17. 77 FR 75699 - Pipeline Safety: Reporting of Exceedances of Maximum Allowable Operating Pressure

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-12-21

    ... Allowable Operating Pressure AGENCY: Pipeline and Hazardous Materials Safety Administration (PHMSA); DOT... owners and operators of gas transmission pipelines that if the pipeline pressure exceeds maximum allowable operating pressure (MAOP) plus the build-up allowed for operation of pressure-limiting or...

  18. 49 CFR 192.619 - Maximum allowable operating pressure: Steel or plastic pipelines.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 3 2014-10-01 2014-10-01 false Maximum allowable operating pressure: Steel or... Operations § 192.619 Maximum allowable operating pressure: Steel or plastic pipelines. (a) No person may operate a segment of steel or plastic pipeline at a pressure that exceeds a maximum allowable...

  19. 49 CFR 192.619 - Maximum allowable operating pressure: Steel or plastic pipelines.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 3 2012-10-01 2012-10-01 false Maximum allowable operating pressure: Steel or... Operations § 192.619 Maximum allowable operating pressure: Steel or plastic pipelines. (a) No person may operate a segment of steel or plastic pipeline at a pressure that exceeds a maximum allowable...

  20. 49 CFR 192.619 - Maximum allowable operating pressure: Steel or plastic pipelines.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 3 2010-10-01 2010-10-01 false Maximum allowable operating pressure: Steel or... Operations § 192.619 Maximum allowable operating pressure: Steel or plastic pipelines. (a) No person may operate a segment of steel or plastic pipeline at a pressure that exceeds a maximum allowable...

  1. 49 CFR 192.619 - Maximum allowable operating pressure: Steel or plastic pipelines.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 3 2011-10-01 2011-10-01 false Maximum allowable operating pressure: Steel or... Operations § 192.619 Maximum allowable operating pressure: Steel or plastic pipelines. (a) No person may operate a segment of steel or plastic pipeline at a pressure that exceeds a maximum allowable...

  2. 49 CFR 192.619 - Maximum allowable operating pressure: Steel or plastic pipelines.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 3 2013-10-01 2013-10-01 false Maximum allowable operating pressure: Steel or... Operations § 192.619 Maximum allowable operating pressure: Steel or plastic pipelines. (a) No person may operate a segment of steel or plastic pipeline at a pressure that exceeds a maximum allowable...

  3. 46 CFR 54.05-30 - Allowable stress values at low temperatures.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 2 2010-10-01 2010-10-01 false Allowable stress values at low temperatures. 54.05-30... PRESSURE VESSELS Toughness Tests § 54.05-30 Allowable stress values at low temperatures. (a) The Coast... nonferrous materials at low temperature for the purpose of establishing allowable stress values for...

  4. 46 CFR 54.05-30 - Allowable stress values at low temperatures.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 2 2012-10-01 2012-10-01 false Allowable stress values at low temperatures. 54.05-30... PRESSURE VESSELS Toughness Tests § 54.05-30 Allowable stress values at low temperatures. (a) The Coast... nonferrous materials at low temperature for the purpose of establishing allowable stress values for...

  5. 46 CFR 54.05-30 - Allowable stress values at low temperatures.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 2 2011-10-01 2011-10-01 false Allowable stress values at low temperatures. 54.05-30... PRESSURE VESSELS Toughness Tests § 54.05-30 Allowable stress values at low temperatures. (a) The Coast... nonferrous materials at low temperature for the purpose of establishing allowable stress values for...

  6. 46 CFR 54.05-30 - Allowable stress values at low temperatures.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 2 2014-10-01 2014-10-01 false Allowable stress values at low temperatures. 54.05-30... PRESSURE VESSELS Toughness Tests § 54.05-30 Allowable stress values at low temperatures. (a) The Coast... nonferrous materials at low temperature for the purpose of establishing allowable stress values for...

  7. 46 CFR 54.05-30 - Allowable stress values at low temperatures.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 2 2013-10-01 2013-10-01 false Allowable stress values at low temperatures. 54.05-30... PRESSURE VESSELS Toughness Tests § 54.05-30 Allowable stress values at low temperatures. (a) The Coast... nonferrous materials at low temperature for the purpose of establishing allowable stress values for...

  8. 49 CFR 192.623 - Maximum and minimum allowable operating pressure; Low-pressure distribution systems.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 3 2013-10-01 2013-10-01 false Maximum and minimum allowable operating pressure; Low-pressure distribution systems. 192.623 Section 192.623 Transportation Other Regulations Relating... SAFETY STANDARDS Operations § 192.623 Maximum and minimum allowable operating pressure;...

  9. 49 CFR 192.621 - Maximum allowable operating pressure: High-pressure distribution systems.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 3 2013-10-01 2013-10-01 false Maximum allowable operating pressure: High-pressure distribution systems. 192.621 Section 192.621 Transportation Other Regulations Relating to... STANDARDS Operations § 192.621 Maximum allowable operating pressure: High-pressure distribution systems....

  10. 49 CFR 192.621 - Maximum allowable operating pressure: High-pressure distribution systems.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... STANDARDS Operations § 192.621 Maximum allowable operating pressure: High-pressure distribution systems. (a) No person may operate a segment of a high pressure distribution system at a pressure that exceeds the... segment of a distribution system otherwise designed to operate at over 60 p.s.i. (414 kPa) gage,...

  11. Temperature Oscillations in Loop Heat Pipe Operation

    NASA Technical Reports Server (NTRS)

    Ku, Jentung; Ottenstein, Laura; Kobel, Mark; Rogers, Paul; Kaya, Tarik; Paquin, Krista C. (Technical Monitor)

    2000-01-01

    Loop heat pipes (LHPs) are versatile two-phase heat transfer devices that have gained increasing acceptance for space and terrestrial applications. The operating temperature of an LHP is a function of its operating conditions. The LHP usually reaches a steady operating temperature for a given heat load and sink temperature. The operating temperature will change when the heat load and/or the sink temperature changes, but eventually reaches another steady state in most cases. Under certain conditions, however, the loop operating temperature never really reaches a true steady state, but instead becomes oscillatory. This paper discusses the temperature oscillation phenomenon using test data from a miniature LHP.

  12. 49 CFR 192.623 - Maximum and minimum allowable operating pressure; Low-pressure distribution systems.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... distribution systems. (a) No person may operate a low-pressure distribution system at a pressure high enough to...) No person may operate a low pressure distribution system at a pressure lower than the minimum... 49 Transportation 3 2010-10-01 2010-10-01 false Maximum and minimum allowable operating...

  13. 40 CFR 73.80 - Operation of allowance reserve program for conservation and renewable energy.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... for conservation and renewable energy. 73.80 Section 73.80 Protection of Environment ENVIRONMENTAL... and Renewable Energy Reserve § 73.80 Operation of allowance reserve program for conservation and renewable energy. (a) General. The Administrator will allocate allowances from the Conservation...

  14. 40 CFR 73.80 - Operation of allowance reserve program for conservation and renewable energy.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... for conservation and renewable energy. 73.80 Section 73.80 Protection of Environment ENVIRONMENTAL... and Renewable Energy Reserve § 73.80 Operation of allowance reserve program for conservation and renewable energy. (a) General. The Administrator will allocate allowances from the Conservation...

  15. 40 CFR 73.80 - Operation of allowance reserve program for conservation and renewable energy.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... for conservation and renewable energy. 73.80 Section 73.80 Protection of Environment ENVIRONMENTAL... and Renewable Energy Reserve § 73.80 Operation of allowance reserve program for conservation and renewable energy. (a) General. The Administrator will allocate allowances from the Conservation...

  16. 40 CFR 73.80 - Operation of allowance reserve program for conservation and renewable energy.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... for conservation and renewable energy. 73.80 Section 73.80 Protection of Environment ENVIRONMENTAL... and Renewable Energy Reserve § 73.80 Operation of allowance reserve program for conservation and renewable energy. (a) General. The Administrator will allocate allowances from the Conservation...

  17. 40 CFR 73.80 - Operation of allowance reserve program for conservation and renewable energy.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... for conservation and renewable energy. 73.80 Section 73.80 Protection of Environment ENVIRONMENTAL... and Renewable Energy Reserve § 73.80 Operation of allowance reserve program for conservation and renewable energy. (a) General. The Administrator will allocate allowances from the Conservation...

  18. 49 CFR 192.620 - Alternative maximum allowable operating pressure for certain steel pipelines.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... for certain steel pipelines. 192.620 Section 192.620 Transportation Other Regulations Relating to... STANDARDS Operations § 192.620 Alternative maximum allowable operating pressure for certain steel pipelines..., 2, or 3 location; (2) The pipeline segment is constructed of steel pipe meeting the...

  19. 49 CFR 192.620 - Alternative maximum allowable operating pressure for certain steel pipelines.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... for certain steel pipelines. 192.620 Section 192.620 Transportation Other Regulations Relating to... STANDARDS Operations § 192.620 Alternative maximum allowable operating pressure for certain steel pipelines..., 2, or 3 location; (2) The pipeline segment is constructed of steel pipe meeting the...

  20. 49 CFR 192.620 - Alternative maximum allowable operating pressure for certain steel pipelines.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... for certain steel pipelines. 192.620 Section 192.620 Transportation Other Regulations Relating to... STANDARDS Operations § 192.620 Alternative maximum allowable operating pressure for certain steel pipelines..., 2, or 3 location; (2) The pipeline segment is constructed of steel pipe meeting the...

  1. 49 CFR 192.620 - Alternative maximum allowable operating pressure for certain steel pipelines.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... for certain steel pipelines. 192.620 Section 192.620 Transportation Other Regulations Relating to... STANDARDS Operations § 192.620 Alternative maximum allowable operating pressure for certain steel pipelines..., 2, or 3 location; (2) The pipeline segment is constructed of steel pipe meeting the...

  2. 49 CFR 192.620 - Alternative maximum allowable operating pressure for certain steel pipelines.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... for certain steel pipelines. 192.620 Section 192.620 Transportation Other Regulations Relating to... STANDARDS Operations § 192.620 Alternative maximum allowable operating pressure for certain steel pipelines..., 2, or 3 location; (2) The pipeline segment is constructed of steel pipe meeting the...

  3. Improved high operating temperature MCT MWIR modules

    NASA Astrophysics Data System (ADS)

    Lutz, H.; Breiter, R.; Figgemeier, H.; Schallenberg, T.; Schirmacher, W.; Wollrab, R.

    2014-06-01

    High operating temperature (HOT) IR-detectors are a key factor to size, weight and power (SWaP) reduced IR-systems. Such systems are essential to provide infantrymen with low-weight handheld systems with increased battery lifetimes or most compact clip-on weapon sights in combination with high electro-optical performance offered by cooled IR-technology. AIM's MCT standard n-on-p technology with vacancy doping has been optimized over many years resulting in MWIR-detectors with excellent electro-optical performance up to operating temperatures of ~120K. In the last years the effort has been intensified to improve this standard technology by introducing extrinsic doping with Gold as an acceptor. As a consequence the dark current could considerably be suppressed and allows for operation at ~140K with good e/o performance. More detailed investigations showed that limitation for HOT > 140K is explained by consequences from rising dark current rather than from defective pixel level. Recently, several crucial parameters were identified showing great promise for further optimization of HOT-performance. Among those, p-type concentration could successfully be reduced from the mid 1016 / cm3 to the lower 1015/ cm3 range. Since AIM is one of the leading manufacturers of split linear cryocoolers, an increase in operating temperature will directly lead to IR-modules with improved SWaP characteristics by making use of the miniature members of its SX cooler family with single piston and balancer technology. The paper will present recent progress in the development of HOT MWIR-detector arrays at AIM and show electro-optical performance data in comparison to focal plane arrays produced in the standard technology.

  4. Lower operating temperatures oxidize VOCs

    SciTech Connect

    Chen, J.

    1996-12-01

    Regenerative catalytic oxidation (RCO) is a new volatile organic compound (VOC) abatement technology that is gaining acceptance in plants where energy costs are high and hours of operation are long. By combining the features of thermal and catalytic oxidation, RCO technology provides an efficient and cost-effective solution to air pollution problems in a variety of industries where hours of operation reach 4,000 annually, and the challenge is growing to reduce energy and operating costs, yet comply with increasingly stringent VOC control regulations. These may include: printed circuit board fabrication (laminate manufacturing), printing (lithography and flexography), coating (cans, coils and fabrics), forest products (production of woods ranging from plywood to medium- and high-density fiberboard) and automotive OEM (spray-paint booths) and component manufacturing (parts spray-painting, resin components, adhesive components, miscellaneous metalworking applications).

  5. 49 CFR 192.328 - Additional construction requirements for steel pipe using alternative maximum allowable operating...

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 3 2014-10-01 2014-10-01 false Additional construction requirements for steel pipe using alternative maximum allowable operating pressure. 192.328 Section 192.328 Transportation... Lines and Mains § 192.328 Additional construction requirements for steel pipe using alternative...

  6. 49 CFR 192.328 - Additional construction requirements for steel pipe using alternative maximum allowable operating...

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 3 2012-10-01 2012-10-01 false Additional construction requirements for steel pipe using alternative maximum allowable operating pressure. 192.328 Section 192.328 Transportation... Lines and Mains § 192.328 Additional construction requirements for steel pipe using alternative...

  7. 49 CFR 192.328 - Additional construction requirements for steel pipe using alternative maximum allowable operating...

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 3 2011-10-01 2011-10-01 false Additional construction requirements for steel pipe using alternative maximum allowable operating pressure. 192.328 Section 192.328 Transportation... Lines and Mains § 192.328 Additional construction requirements for steel pipe using alternative...

  8. Temperature and Pressure Sensors Based on Spin-Allowed Broadband Luminescence of Doped Orthorhombic Perovskite Structures

    NASA Technical Reports Server (NTRS)

    Eldridge, Jeffrey I. (Inventor); Chambers, Matthew D. (Inventor)

    2014-01-01

    Systems and methods that are capable of measuring pressure or temperature based on luminescence are discussed herein. These systems and methods are based on spin-allowed broadband luminescence of sensors with orthorhombic perovskite structures of rare earth aluminates doped with chromium or similar transition metals, such as chromium-doped gadolinium aluminate. Luminescence from these sensors can be measured to determine at least one of temperature or pressure, based on either the intense luminescence of these sensors, even at high temperatures, or low temperature techniques discussed herein.

  9. 14 CFR 25.1527 - Ambient air temperature and operating altitude.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 14 Aeronautics and Space 1 2012-01-01 2012-01-01 false Ambient air temperature and operating... Information Operating Limitations § 25.1527 Ambient air temperature and operating altitude. The extremes of the ambient air temperature and operating altitude for which operation is allowed, as limited...

  10. 14 CFR 25.1527 - Ambient air temperature and operating altitude.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 14 Aeronautics and Space 1 2014-01-01 2014-01-01 false Ambient air temperature and operating... Information Operating Limitations § 25.1527 Ambient air temperature and operating altitude. The extremes of the ambient air temperature and operating altitude for which operation is allowed, as limited...

  11. 14 CFR 25.1527 - Ambient air temperature and operating altitude.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 14 Aeronautics and Space 1 2013-01-01 2013-01-01 false Ambient air temperature and operating... Information Operating Limitations § 25.1527 Ambient air temperature and operating altitude. The extremes of the ambient air temperature and operating altitude for which operation is allowed, as limited...

  12. 14 CFR 25.1527 - Ambient air temperature and operating altitude.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Ambient air temperature and operating... Information Operating Limitations § 25.1527 Ambient air temperature and operating altitude. The extremes of the ambient air temperature and operating altitude for which operation is allowed, as limited...

  13. 14 CFR 25.1527 - Ambient air temperature and operating altitude.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Ambient air temperature and operating... Information Operating Limitations § 25.1527 Ambient air temperature and operating altitude. The extremes of the ambient air temperature and operating altitude for which operation is allowed, as limited...

  14. Determination of design allowable strength properties of elevated-temperature alloys. Part 1: Coated columbium alloys

    NASA Technical Reports Server (NTRS)

    Favor, R. J.; Maykuth, D. J.; Bartlett, E. S.; Mindlin, H.

    1972-01-01

    A program to determine the characteristics of two coated columbium alloy systems for spacecraft structures is discussed. The alloy was evaluated as coated base material, coated butt-welded material, and material thermal/pressure cycled prior to testing up to 30 cycles. Evaluation was by means of tensile tests covering the temperature range to 2400 F. Design allowables were computed and are presented as tables of data. The summary includes a room temperature property table, effect of temperature curves, and typical stress-strain curves.

  15. Passive components for high temperature operation

    NASA Technical Reports Server (NTRS)

    Raymond, L. S.; Clark, D. R.; Black, D. O.; Hamilton, D. J.; Kerwin, W.

    1981-01-01

    The development of resistors, capacitors, and interconnect metalizations utilizing a low pressure chemical vapor deposition (LPCVD) process is described. The LPCVD process allows the passive components to be fabricated at temperatures higher than their highest operating temperatures. The deposition of thin films by LPCVD is accomplished by reacting one or more gases on the surface of a heated substrate. The substrates to be coated are placed on a graphite susceptor and then loaded into the center of a quartz reaction tube. The RF power is applied to the coil on the outside of the reaction tube which in turn is coupled into the graphite susceptor causing it to heat. Pressures of several torr or less are typical, with carrier flow rates of 0.1 to 2.0 liters/min. Nitrogen, hydrogen, and helium are typical carrier gases. These are controlled with mass flow controllers and the pressure is continuously monitored with a capacitive manometer. Materials selection and device testing are also discussed.

  16. Extreme operative temperatures are better descriptors of the thermal environment than mean temperatures.

    PubMed

    Camacho, Agustín; Trefaut Rodrigues, Miguel; Navas, Carlos

    2015-01-01

    In ecological studies of thermal biology the thermal environment is most frequently described using the mean or other measures of central tendency in environmental temperatures. However, this procedure may hide biologically relevant thermal variation for ectotherms, potentially misleading interpretations. Extremes of operative temperatures (EOT) can help with this problem by bracketing the thermal environment of focal animals. Within this paper, we quantify how mean operative temperatures relate to the range of simultaneously available operative temperatures (a measure of error). We also show how EOT: 1) detect more thermal differences among microsites than measures of central tendency, like the mean OT, 2) allow inferring on microsite use by ectothermic animals, and 3) clarify the relationships between field operative temperatures and temperatures measured at weather stations (WS). To do that, we explored operative temperatures measured at four sites of the Brazilian Caatingas and their correspondent nearest weather stations. We found that the daily mean OT can hide temperature ranges of 41 °C simultaneously available at our study sites. In addition, EOT detected more thermal differences among microsites than central quantiles. We also show how EOT allow inferring about microsite use of ectothermic animals in a given site. Finally, the daily maximum temperature and the daily temperature range measured at WSs predicted well the minimum available field OT at localities many kilometers away. Based on our results, we recommend the use of EOT, instead of mean OT, in thermal ecology studies.

  17. Experimental Generation of Squeezed Cat States with an Operation Allowing Iterative Growth

    NASA Astrophysics Data System (ADS)

    Etesse, Jean; Bouillard, Martin; Kanseri, Bhaskar; Tualle-Brouri, Rosa

    2015-05-01

    We present what is, to our knowledge, the first implementation of a "cat breeding" operation, which allows an iterative growth of cat states. We thus report the experimental generation of a squeezed cat state from two single photon Fock states, which can be seen as cat states with zero amplitude. These Fock states are mixed on a symmetrical beam splitter, and the generation is heralded by a homodyne measurement in one of the two output arms. The output state has a fidelity of 61% with an even squeezed cat state of amplitude α =1.63 . This hybrid operation opens up new prospects in quantum optics, as the protocol depicted here can be iterated in order to produce new kinds of mesoscopic states.

  18. Experimental generation of squeezed cat States with an operation allowing iterative growth.

    PubMed

    Etesse, Jean; Bouillard, Martin; Kanseri, Bhaskar; Tualle-Brouri, Rosa

    2015-05-15

    We present what is, to our knowledge, the first implementation of a "cat breeding" operation, which allows an iterative growth of cat states. We thus report the experimental generation of a squeezed cat state from two single photon Fock states, which can be seen as cat states with zero amplitude. These Fock states are mixed on a symmetrical beam splitter, and the generation is heralded by a homodyne measurement in one of the two output arms. The output state has a fidelity of 61% with an even squeezed cat state of amplitude α=1.63. This hybrid operation opens up new prospects in quantum optics, as the protocol depicted here can be iterated in order to produce new kinds of mesoscopic states.

  19. Electronics Demonstrated for Low- Temperature Operation

    NASA Technical Reports Server (NTRS)

    Patterson, Richard L.; Hammond, Ahmad; Gerber, Scott S.

    2000-01-01

    The operation of electronic systems at cryogenic temperatures is anticipated for many NASA spacecraft, such as planetary explorers and deep space probes. For example, an unheated interplanetary probe launched to explore the rings of Saturn would experience an average temperature near Saturn of about 183 C. Electronics capable of low-temperature operation in the harsh deep space environment also would help improve circuit performance, increase system efficiency, and reduce payload development and launch costs. An ongoing research and development program on low-temperature electronics at the NASA Glenn Research Center at Lewis Field is focusing on the design of efficient power systems that can survive and exploit the advantages of low-temperature environments. The targeted systems, which are mission driven, include converters, inverters, controls, digital circuits, and special-purpose circuits. Initial development efforts successfully demonstrated the low-temperature operation and cold-restart of several direct-current/direct-current (dc/dc) converters based on different types of circuit design, some with superconducting inductors. The table lists some of these dc/dc converters with their properties, and the photograph shows a high-voltage, high-power dc/dc converter designed for an ion propulsion system for low-temperature operation. The development efforts of advanced electronic systems and the supporting technologies for low-temperature operation are being carried out in-house and through collaboration with other Government agencies, industry, and academia. The Low Temperature Electronics Program supports missions and development programs at NASA s Jet Propulsion Laboratory and Goddard Space Flight Center. The developed technologies will be transferred to commercial end users for applications such as satellite infrared sensors and medical diagnostic equipment.

  20. The effect of maximum-allowable payload temperature on the mass of a multimegawatt space-based platform

    SciTech Connect

    Dobranich, D.

    1987-08-01

    Calculations were performed to determine the mass of a space-based platform as a function of the maximum-allowed operating temperature of the electrical equipment within the platform payload. Two computer programs were used in conjunction to perform these calculations. The first program was used to determine the mass of the platform reactor, shield, and power conversion system. The second program was used to determine the mass of the main and secondary radiators of the platform. The main radiator removes the waste heat associated with the power conversion system and the secondary radiator removes the waste heat associated with the platform payload. These calculations were performed for both Brayton and Rankine cycle platforms with two different types of payload cooling systems: a pumped-loop system (a heat exchanger with a liquid coolant) and a refrigerator system. The results indicate that increases in the maximum-allowed payload temperature offer significant platform mass savings for both the Brayton and Rankine cycle platforms with either the pumped-loop or refrigerator payload cooling systems. Therefore, with respect to platform mass, the development of high temperature electrical equipment would be advantageous. 3 refs., 24 figs., 7 tabs.

  1. 33 CFR 159.119 - Operability test; temperature range.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 33 Navigation and Navigable Waters 2 2012-07-01 2012-07-01 false Operability test; temperature... Operability test; temperature range. The device must operate in an ambient temperature of 5 °C with inlet operating fluid temperature varying from 2 °C to 32 °C and in an ambient temperature of 50 °C with...

  2. 33 CFR 159.119 - Operability test; temperature range.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 33 Navigation and Navigable Waters 2 2011-07-01 2011-07-01 false Operability test; temperature... Operability test; temperature range. The device must operate in an ambient temperature of 5 °C with inlet operating fluid temperature varying from 2 °C to 32 °C and in an ambient temperature of 50 °C with...

  3. 33 CFR 159.119 - Operability test; temperature range.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 33 Navigation and Navigable Waters 2 2014-07-01 2014-07-01 false Operability test; temperature... Operability test; temperature range. The device must operate in an ambient temperature of 5 °C with inlet operating fluid temperature varying from 2 °C to 32 °C and in an ambient temperature of 50 °C with...

  4. 33 CFR 159.119 - Operability test; temperature range.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 33 Navigation and Navigable Waters 2 2010-07-01 2010-07-01 false Operability test; temperature... Operability test; temperature range. The device must operate in an ambient temperature of 5 °C with inlet operating fluid temperature varying from 2 °C to 32 °C and in an ambient temperature of 50 °C with...

  5. 33 CFR 159.119 - Operability test; temperature range.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 33 Navigation and Navigable Waters 2 2013-07-01 2013-07-01 false Operability test; temperature... Operability test; temperature range. The device must operate in an ambient temperature of 5 °C with inlet operating fluid temperature varying from 2 °C to 32 °C and in an ambient temperature of 50 °C with...

  6. Allowing variance may enlarge the safe operating space for exploited ecosystems

    PubMed Central

    Carpenter, Stephen R.; Brock, William A.; Folke, Carl; van Nes, Egbert H.; Scheffer, Marten

    2015-01-01

    Variable flows of food, water, or other ecosystem services complicate planning. Management strategies that decrease variability and increase predictability may therefore be preferred. However, actions to decrease variance over short timescales (2–4 y), when applied continuously, may lead to long-term ecosystem changes with adverse consequences. We investigated the effects of managing short-term variance in three well-understood models of ecosystem services: lake eutrophication, harvest of a wild population, and yield of domestic herbivores on a rangeland. In all cases, actions to decrease variance can increase the risk of crossing critical ecosystem thresholds, resulting in less desirable ecosystem states. Managing to decrease short-term variance creates ecosystem fragility by changing the boundaries of safe operating spaces, suppressing information needed for adaptive management, cancelling signals of declining resilience, and removing pressures that may build tolerance of stress. Thus, the management of variance interacts strongly and inseparably with the management of resilience. By allowing for variation, learning, and flexibility while observing change, managers can detect opportunities and problems as they develop while sustaining the capacity to deal with them. PMID:26438857

  7. New Waste Calciner High Temperature Operation

    SciTech Connect

    Swenson, M.C.

    2000-09-01

    A new Calciner flowsheet has been developed to process the sodium-bearing waste (SBW) in the INTEC Tank Farm. The new flowsheet increases the normal Calciner operating temperature from 500 C to 600 C. At the elevated temperature, sodium in the waste forms stable aluminates, instead of nitrates that melt at calcining temperatures. From March through May 2000, the new high-temperature flowsheet was tested in the New Waste Calcining Facility (NWCF) Calciner. Specific test criteria for various Calciner systems (feed, fuel, quench, off-gas, etc.) were established to evaluate the long-term operability of the high-temperature flowsheet. This report compares in detail the Calciner process data with the test criteria. The Calciner systems met or exceeded all test criteria. The new flowsheet is a visible, long-term method of calcining SBW. Implementation of the flowsheet will significantly increase the calcining rate of SBW and reduce the amount of calcine produced by reducing the amount of chemical additives to the Calciner. This will help meet the future waste processing milestones and regulatory needs such as emptying the Tank Farm.

  8. 49 CFR 192.621 - Maximum allowable operating pressure: High-pressure distribution systems.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... cast iron pipe in which there are unreinforced bell and spigot joints. (4) The pressure limits to which..., particularly known corrosion and the actual operating pressures. (b) No person may operate a segment...

  9. 49 CFR 192.621 - Maximum allowable operating pressure: High-pressure distribution systems.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... cast iron pipe in which there are unreinforced bell and spigot joints. (4) The pressure limits to which..., particularly known corrosion and the actual operating pressures. (b) No person may operate a segment...

  10. 49 CFR 192.621 - Maximum allowable operating pressure: High-pressure distribution systems.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... cast iron pipe in which there are unreinforced bell and spigot joints. (4) The pressure limits to which..., particularly known corrosion and the actual operating pressures. (b) No person may operate a segment...

  11. Wide-Temperature-Range Integrated Operational Amplifier

    NASA Technical Reports Server (NTRS)

    Mojarradi, Mohammad; Levanas, Greg; Chen, Yuan; Kolawa, Elizabeth; Cozy, Raymond; Blalock, Benjamin; Greenwell, Robert; Terry, Stephen

    2007-01-01

    A document discusses a silicon-on-insulator (SOI) complementary metal oxide/semiconductor (CMOS) integrated- circuit operational amplifier to be replicated and incorporated into sensor and actuator systems of Mars-explorer robots. This amplifier is designed to function at a supply potential less than or equal to 5.5 V, at any temperature from -180 to +120 C. The design is implemented on a commercial radiation-hard SOI CMOS process rated for a supply potential of less than or equal to 3.6 V and temperatures from -55 to +110 C. The design incorporates several innovations to achieve this, the main ones being the following: NMOS transistor channel lengths below 1 m are generally not used because research showed that this change could reduce the adverse effect of hot carrier injection on the lifetimes of transistors at low temperatures. To enable the amplifier to withstand the 5.5-V supply potential, a circuit topology including cascade devices, clamping devices, and dynamic voltage biasing was adopted so that no individual transistor would be exposed to more than 3.6 V. To minimize undesired variations in performance over the temperature range, the transistors in the amplifier are biased by circuitry that maintains a constant inversion coefficient over the temperature range.

  12. Electronics for Low-Temperature Space Operation Being Evaluated

    NASA Technical Reports Server (NTRS)

    Patterson, Richard L.; Hammoud, Ahmad

    2001-01-01

    Electronic components and systems capable of low-temperature operation are needed for many future NASA missions where it is desirable to have smaller, lighter, and cheaper (unheated) spacecraft. These missions include Mars (-20 to -120 C) orbiters, landers, and rovers; Europa (-150 C) oceanic exploratory probes and instrumentation; Saturn (-183 C) and Pluto (-229 C) interplanetary probes. At the present, most electronic equipment can operate down to only -55 C. It would be very desirable to have electronic components that expand the operating temperature range down to -233 C. The successful development of these low-temperature components will eventually allow space probes and onboard electronics to operate in very cold environments (out as far as the planet Pluto). As a result, radioisotope heating units, which are used presently to keep space electronics near room temperature, will be reduced in number or eliminated. The new cold electronics will make spacecraft design and operation simpler, more flexible, more reliable, lighter, and cheaper. Researchers at the NASA Glenn Research Center are evaluating potential commercial off-the- shelf devices and are developing new electronic components that will tolerate operation at low temperatures down to -233 C. This work is being carried out mainly inhouse and also through university grants and commercial contracts. The components include analog-to-digital converters, semiconductor switches, capacitors, dielectric and packaging material, and batteries. For example, the effect of low temperature on the capacitance of three different types of capacitors is shown in the graph. Using these advanced components, system products will be developed, including dc/dc converters, battery charge/discharge management systems, digital control electronics, transducers, and sensor instrumentation.

  13. Implementation of the NETOS (Network Operating System) Operated System in Ada with Modifications to Allow Variable Length Messages

    DTIC Science & Technology

    1988-12-01

    length array of type BYTE. This allowed for easy manipulation of bytes to frames to packets to messages. The hard typing of Ada had to be overcome as there...Fortunately, Janus/Ada had a library package, DOSCALL, which provided low-level I/O 3 routines. A type BSTRING was defined to allow a variable

  14. Linear optics only allows every possible quantum operation for one photon or one port

    NASA Astrophysics Data System (ADS)

    Moyano-Fernández, Julio José; Garcia-Escartin, Juan Carlos

    2017-01-01

    We study the evolution of the quantum state of n photons in m different modes when they go through a lossless linear optical system. We show that there are quantum evolution operators U that cannot be built with linear optics alone unless the number of photons or the number of modes is equal to one. The evolution for single photons can be controlled with the known realization of any unitary proved by Reck, Zeilinger, Bernstein and Bertani. The evolution for a single mode corresponds to the trivial evolution in a phase shifter. We analyze these two cases and prove that any other combination of the number of photons and modes produces a Hilbert state too large for the linear optics system to give any desired evolution.

  15. 42 CFR 84.98 - Tests during low temperature operation.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 42 Public Health 1 2011-10-01 2011-10-01 false Tests during low temperature operation. 84.98...-Contained Breathing Apparatus § 84.98 Tests during low temperature operation. (a) The applicant shall specify the minimum temperature for safe operation and two persons will perform the tests described...

  16. 42 CFR 84.98 - Tests during low temperature operation.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 42 Public Health 1 2010-10-01 2010-10-01 false Tests during low temperature operation. 84.98...-Contained Breathing Apparatus § 84.98 Tests during low temperature operation. (a) The applicant shall specify the minimum temperature for safe operation and two persons will perform the tests described...

  17. 42 CFR 84.98 - Tests during low temperature operation.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 42 Public Health 1 2012-10-01 2012-10-01 false Tests during low temperature operation. 84.98...-Contained Breathing Apparatus § 84.98 Tests during low temperature operation. (a) The applicant shall specify the minimum temperature for safe operation and two persons will perform the tests described...

  18. 42 CFR 84.98 - Tests during low temperature operation.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 42 Public Health 1 2014-10-01 2014-10-01 false Tests during low temperature operation. 84.98...-Contained Breathing Apparatus § 84.98 Tests during low temperature operation. (a) The applicant shall specify the minimum temperature for safe operation and two persons will perform the tests described...

  19. 42 CFR 84.98 - Tests during low temperature operation.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 42 Public Health 1 2013-10-01 2013-10-01 false Tests during low temperature operation. 84.98...-Contained Breathing Apparatus § 84.98 Tests during low temperature operation. (a) The applicant shall specify the minimum temperature for safe operation and two persons will perform the tests described...

  20. Surface chemistry allows for abiotic precipitation of dolomite at low temperature

    NASA Astrophysics Data System (ADS)

    Roberts, Jennifer A.; Kenward, Paul A.; Fowle, David A.; Goldstein, Robert H.; González, Luis A.; Moore, David S.

    2013-09-01

    Although the mineral dolomite is abundant in ancient low-temperature sedimentary systems, it is scarce in modern systems below 50 °C. Chemical mechanism(s) enhancing its formation remain an enigma because abiotic dolomite has been challenging to synthesize at low temperature in laboratory settings. Microbial enhancement of dolomite precipitation at low temperature has been reported; however, it is still unclear exactly how microorganisms influence reaction kinetics. Here we document the abiotic synthesis of low-temperature dolomite in laboratory experiments and constrain possible mechanisms for dolomite formation. Ancient and modern seawater solution compositions, with identical pH and pCO2, were used to precipitate an ordered, stoichiometric dolomite phase at 30 °C in as few as 20 d. Mg-rich phases nucleate exclusively on carboxylated polystyrene spheres along with calcite, whereas aragonite forms in solution via homogeneous nucleation. We infer that Mg ions are complexed and dewatered by surface-bound carboxyl groups, thus decreasing the energy required for carbonation. These results indicate that natural surfaces, including organic matter and microbial biomass, possessing a high density of carboxyl groups may be a mechanism by which ordered dolomite nuclei form. Although environments rich in organic matter may be of interest, our data suggest that sharp biogeochemical interfaces that promote microbial death, as well as those with high salinity may, in part, control carboxyl-group density on organic carbon surfaces, consistent with origin of dolomites from microbial biofilms, as well as hypersaline and mixing zone environments.

  1. Surface chemistry allows for abiotic precipitation of dolomite at low temperature.

    PubMed

    Roberts, Jennifer A; Kenward, Paul A; Fowle, David A; Goldstein, Robert H; González, Luis A; Moore, David S

    2013-09-03

    Although the mineral dolomite is abundant in ancient low-temperature sedimentary systems, it is scarce in modern systems below 50 °C. Chemical mechanism(s) enhancing its formation remain an enigma because abiotic dolomite has been challenging to synthesize at low temperature in laboratory settings. Microbial enhancement of dolomite precipitation at low temperature has been reported; however, it is still unclear exactly how microorganisms influence reaction kinetics. Here we document the abiotic synthesis of low-temperature dolomite in laboratory experiments and constrain possible mechanisms for dolomite formation. Ancient and modern seawater solution compositions, with identical pH and pCO2, were used to precipitate an ordered, stoichiometric dolomite phase at 30 °C in as few as 20 d. Mg-rich phases nucleate exclusively on carboxylated polystyrene spheres along with calcite, whereas aragonite forms in solution via homogeneous nucleation. We infer that Mg ions are complexed and dewatered by surface-bound carboxyl groups, thus decreasing the energy required for carbonation. These results indicate that natural surfaces, including organic matter and microbial biomass, possessing a high density of carboxyl groups may be a mechanism by which ordered dolomite nuclei form. Although environments rich in organic matter may be of interest, our data suggest that sharp biogeochemical interfaces that promote microbial death, as well as those with high salinity may, in part, control carboxyl-group density on organic carbon surfaces, consistent with origin of dolomites from microbial biofilms, as well as hypersaline and mixing zone environments.

  2. Final Report-- A Novel Storage Method for Concentrating Solar Power Plants Allowing Storage at High Temperature

    SciTech Connect

    Morris, Jeffrey F.

    2014-09-29

    The main objective of the proposed work was the development and testing of a storage method that has the potential to fundamentally change the solar thermal industry. The development of a mathematical model that describes the phenomena involved in the heat storage and recovery was also a main objective of this work. Therefore, the goal was to prepare a design package allowing reliable scale-up and optimization of design.

  3. 49 CFR 192.611 - Change in class location: Confirmation or revision of maximum allowable operating pressure.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... of maximum allowable operating pressure. (a) If the hoop stress corresponding to the established... locations. The corresponding hoop stress may not exceed 72 percent of the SMYS of the pipe in Class 2... pressure per § 192.620, the corresponding hoop stress may not exceed 80 percent of the SMYS of the pipe...

  4. 49 CFR 192.611 - Change in class location: Confirmation or revision of maximum allowable operating pressure.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... of maximum allowable operating pressure. (a) If the hoop stress corresponding to the established... locations. The corresponding hoop stress may not exceed 72 percent of the SMYS of the pipe in Class 2... pressure per § 192.620, the corresponding hoop stress may not exceed 80 percent of the SMYS of the pipe...

  5. Surface chemistry allows for abiotic precipitation of dolomite at low temperature

    PubMed Central

    Roberts, Jennifer A.; Kenward, Paul A.; Fowle, David A.; Goldstein, Robert H.; González, Luis A.; Moore, David S.

    2013-01-01

    Although the mineral dolomite is abundant in ancient low-temperature sedimentary systems, it is scarce in modern systems below 50 °C. Chemical mechanism(s) enhancing its formation remain an enigma because abiotic dolomite has been challenging to synthesize at low temperature in laboratory settings. Microbial enhancement of dolomite precipitation at low temperature has been reported; however, it is still unclear exactly how microorganisms influence reaction kinetics. Here we document the abiotic synthesis of low-temperature dolomite in laboratory experiments and constrain possible mechanisms for dolomite formation. Ancient and modern seawater solution compositions, with identical pH and pCO2, were used to precipitate an ordered, stoichiometric dolomite phase at 30 °C in as few as 20 d. Mg-rich phases nucleate exclusively on carboxylated polystyrene spheres along with calcite, whereas aragonite forms in solution via homogeneous nucleation. We infer that Mg ions are complexed and dewatered by surface-bound carboxyl groups, thus decreasing the energy required for carbonation. These results indicate that natural surfaces, including organic matter and microbial biomass, possessing a high density of carboxyl groups may be a mechanism by which ordered dolomite nuclei form. Although environments rich in organic matter may be of interest, our data suggest that sharp biogeochemical interfaces that promote microbial death, as well as those with high salinity may, in part, control carboxyl-group density on organic carbon surfaces, consistent with origin of dolomites from microbial biofilms, as well as hypersaline and mixing zone environments. PMID:23964124

  6. Determining Solar-Cell Operating Temperature

    NASA Technical Reports Server (NTRS)

    Griffith, J. S.; Rathod, M. S.; Paslaski, J. S.

    1983-01-01

    Laboratory test measures effect of windspeed and wind directon. Series of tests shows solar-photovoltaic cell temperature extremely sensitive to windspeed, moderately sensitive to wind direction, and rather insensitive to ambient temperature.

  7. Two-barrier stability that allows low-power operation in current-induced domain-wall motion.

    PubMed

    Kim, Kab-Jin; Hiramatsu, Ryo; Koyama, Tomohiro; Ueda, Kohei; Yoshimura, Yoko; Chiba, Daichi; Kobayashi, Kensuke; Nakatani, Yoshinobu; Fukami, Shunsuke; Yamanouchi, Michihiko; Ohno, Hideo; Kohno, Hiroshi; Tatara, Gen; Ono, Teruo

    2013-01-01

    Energy barriers in magnetization reversal dynamics have long been of interest because the barrier height determines the thermal stability of devices as well as the threshold force triggering their dynamics. Especially in memory and logic applications, there is a dilemma between the thermal stability of bit data and the operation power of devices, because larger energy barriers for higher thermal stability inevitably lead to larger magnetic fields (or currents) for operation. Here we show that this is not the case for current-induced magnetic domain-wall motion induced by adiabatic spin-transfer torque. By quantifying domain-wall depinning energy barriers by magnetic field and current, we find that there exist two different pinning barriers, extrinsic and intrinsic energy barriers, which govern the thermal stability and threshold current, respectively. This unique two-barrier system allows low-power operation with high thermal stability, which is impossible in conventional single-barrier systems.

  8. Two-barrier stability that allows low-power operation in current-induced domain-wall motion

    NASA Astrophysics Data System (ADS)

    Kim, Kab-Jin; Hiramatsu, Ryo; Koyama, Tomohiro; Ueda, Kohei; Yoshimura, Yoko; Chiba, Daichi; Kobayashi, Kensuke; Nakatani, Yoshinobu; Fukami, Shunsuke; Yamanouchi, Michihiko; Ohno, Hideo; Kohno, Hiroshi; Tatara, Gen; Ono, Teruo

    2013-06-01

    Energy barriers in magnetization reversal dynamics have long been of interest because the barrier height determines the thermal stability of devices as well as the threshold force triggering their dynamics. Especially in memory and logic applications, there is a dilemma between the thermal stability of bit data and the operation power of devices, because larger energy barriers for higher thermal stability inevitably lead to larger magnetic fields (or currents) for operation. Here we show that this is not the case for current-induced magnetic domain-wall motion induced by adiabatic spin-transfer torque. By quantifying domain-wall depinning energy barriers by magnetic field and current, we find that there exist two different pinning barriers, extrinsic and intrinsic energy barriers, which govern the thermal stability and threshold current, respectively. This unique two-barrier system allows low-power operation with high thermal stability, which is impossible in conventional single-barrier systems.

  9. Wide-temperature integrated operational amplifier

    NASA Technical Reports Server (NTRS)

    Mojarradi, Mohammad (Inventor); Levanas, Greg (Inventor); Chen, Yuan (Inventor); Cozy, Raymond S. (Inventor); Greenwell, Robert (Inventor); Terry, Stephen (Inventor); Blalock, Benjamin J. (Inventor)

    2009-01-01

    The present invention relates to a reference current circuit. The reference circuit comprises a low-level current bias circuit, a voltage proportional-to-absolute temperature generator for creating a proportional-to-absolute temperature voltage (VPTAT), and a MOSFET-based constant-IC regulator circuit. The MOSFET-based constant-IC regulator circuit includes a constant-IC input and constant-IC output. The constant-IC input is electrically connected with the VPTAT generator such that the voltage proportional-to-absolute temperature is the input into the constant-IC regulator circuit. Thus the constant-IC output maintains the constant-IC ratio across any temperature range.

  10. Nanoscale temperature mapping in operating microelectronic devices

    DOE PAGES

    Mecklenburg, Matthew; Hubbard, William A.; White, E. R.; ...

    2015-02-05

    We report that modern microelectronic devices have nanoscale features that dissipate power nonuniformly, but fundamental physical limits frustrate efforts to detect the resulting temperature gradients. Contact thermometers disturb the temperature of a small system, while radiation thermometers struggle to beat the diffraction limit. Exploiting the same physics as Fahrenheit’s glass-bulb thermometer, we mapped the thermal expansion of Joule-heated, 80-nanometer-thick aluminum wires by precisely measuring changes in density. With a scanning transmission electron microscope (STEM) and electron energy loss spectroscopy (EELS), we quantified the local density via the energy of aluminum’s bulk plasmon. Rescaling density to temperature yields maps with amore » statistical precision of 3 kelvin/hertz₋1/2, an accuracy of 10%, and nanometer-scale resolution. Lastly, many common metals and semiconductors have sufficiently sharp plasmon resonances to serve as their own thermometers.« less

  11. Nanoscale temperature mapping in operating microelectronic devices

    SciTech Connect

    Mecklenburg, Matthew; Hubbard, William A.; White, E. R.; Dhall, Rohan; Cronin, Stephen B.; Aloni, Shaul; Regan, B. C.

    2015-02-05

    We report that modern microelectronic devices have nanoscale features that dissipate power nonuniformly, but fundamental physical limits frustrate efforts to detect the resulting temperature gradients. Contact thermometers disturb the temperature of a small system, while radiation thermometers struggle to beat the diffraction limit. Exploiting the same physics as Fahrenheit’s glass-bulb thermometer, we mapped the thermal expansion of Joule-heated, 80-nanometer-thick aluminum wires by precisely measuring changes in density. With a scanning transmission electron microscope (STEM) and electron energy loss spectroscopy (EELS), we quantified the local density via the energy of aluminum’s bulk plasmon. Rescaling density to temperature yields maps with a statistical precision of 3 kelvin/hertz₋1/2, an accuracy of 10%, and nanometer-scale resolution. Lastly, many common metals and semiconductors have sufficiently sharp plasmon resonances to serve as their own thermometers.

  12. Temperature Sensing Above 1000 C Using Cr-Doped GdAlO3 Spin-Allowed Broadband Luminescence

    NASA Technical Reports Server (NTRS)

    Eldridge, Jeffrey I.; Chambers, Matthew D.

    2012-01-01

    Cr-doped GdAlO3 (Cr:GdAlO3) is shown to produce remarkably high-intensity spin-allowed broadband luminescence with sufficiently long decay times to make effective luminescence-decay-time based temperature measurements above 1000 C. This phosphor is therefore an attractive alternative to the much lower luminescence intensity rare-earth-doped thermographic phosphors that are typically utilized at these elevated temperatures. In particular, Cr:GdAlO3 will be preferred over rare-earth-doped phosphors, such as Dy:YAG, at temperatures up to 1200 C for intensity-starved situations when the much lower emission intensity from rare-earth-doped phosphors is insufficient for accurate temperature measurements in the presence of significant radiation background. While transition-metal-doped phosphors such as Cr:Al2O3 (ruby) are known to exhibit high luminescence intensity at low dopant concentrations, quenching due to nonradiative decay pathways competing with the (sup 2)E to (sup 4)A(sub 2) radiative transition (R line) has typically restricted their use for temperature sensing to below 600 C. Thermal quenching of the broadband (sup 4)T(sub 2) to (sup 4)A(sub 2) radiative transition from Cr:GdAlO3, however, is delayed until much higher temperatures (above 1000 C). This spin-allowed broadband emission persists to high temperatures because the lower-lying (sup 2)E energy level acts as a reservoir to thermally populate the higher shorter-lived (sup 4)T(sub 2) energy level and because the activation energy for nonradiative crossover relaxation from the (sup 4)T(sub 2) level to the (sup 4)A(sub 2) ground state is high. The strong crystal field associated with the tight bonding of the AlO6 octahedra in the GdAlO3 perovskite structure is responsible for this behavior.

  13. Short communication: calf body temperature following chemical disbudding with sedation: effects of milk allowance and supplemental heat.

    PubMed

    Vasseur, E; Rushen, J; de Passillé, A M

    2014-01-01

    The use of caustic paste combined with a sedative is one of the least painful methods for disbudding. It is recommended to disbud at as early as 5d of age. However, the sedative xylazine reportedly causes a decrease in core temperature. Furthermore, young calves do not thermoregulate efficiently. We investigated the effects of disbudding calves at 5d of age using caustic paste and xylazine sedation on body temperature, activity, and milk intake of 46 individually housed 5-d-old calves in a 2×2 factorial design, with milk fed at 4.5L/d (low-fed calves) versus 9L/d (high-fed calves), with or without a heat lamp. Body temperature, calf activity (standing time), and barn temperature were monitored continuously using automatic data loggers on the day of, before the day of, and the day after disbudding. All calves were injected intramuscularly with 0.25mL of 2mg/mL xylazine 20min before disbudding (dose: 0.12±0.003mL/kg of BW). We found that the body temperature of 5-d-old calves decreased immediately after the injection of the sedative xylazine. The body temperature of calves decreased 0.9±0.09°C and it took 3.8±0.32h to climb back to the preinjection body temperature. Calves that were fed the lower amount of milk, received a higher dose of xylazine (mL/kg BW), or were disbudded in a colder environment were more affected by body temperature variations (lower and longest decrease in body temperature and higher magnitude). Calf activity recovery followed the pattern of body temperature recovery. Milk allowance and supplemental heat did not help enhance recovery during the 6h following the procedure. The disbudding procedure did not affect milk intake but calves with less body temperature decrease or kept in a warmer environment drank more milk following disbudding. Low-fed calves were overall more affected by the procedure than high-fed calves during the disbudding day and the following day (greater decrease in body temperature and drank less in the colder

  14. Verilog-A Device Models for Cryogenic Temperature Operation of Bulk Silicon CMOS Devices

    NASA Technical Reports Server (NTRS)

    Akturk, Akin; Potbhare, Siddharth; Goldsman, Neil; Holloway, Michael

    2012-01-01

    Verilog-A based cryogenic bulk CMOS (complementary metal oxide semiconductor) compact models are built for state-of-the-art silicon CMOS processes. These models accurately predict device operation at cryogenic temperatures down to 4 K. The models are compatible with commercial circuit simulators. The models extend the standard BSIM4 [Berkeley Short-channel IGFET (insulated-gate field-effect transistor ) Model] type compact models by re-parameterizing existing equations, as well as adding new equations that capture the physics of device operation at cryogenic temperatures. These models will allow circuit designers to create optimized, reliable, and robust circuits operating at cryogenic temperatures.

  15. Operation of an opamp at liquid helium temperature.

    NASA Astrophysics Data System (ADS)

    Ng, K.-W.

    1994-02-01

    The stray capacitance between long wires in a cryogenics systems will slow down measurement rate, and also introduce unnecessary noise pick up. It is necessary to install the preamplifier as close to the signal source as possible to diminish the capacitive coupling effects. The most commonly used semiconducting device for this purpose is the MOSFET, which can function at liquid helium temperatures. Under special operation procedures, an all MOSFET operational amplifier can also be operated at liquid helium temperature. The use of opamp will simplify the construction of more complicated circuitry for low temperature applications.

  16. System for controlling the operating temperature of a fuel cell

    DOEpatents

    Fabis, Thomas R.; Makiel, Joseph M.; Veyo, Stephen E.

    2006-06-06

    A method and system are provided for improved control of the operating temperature of a fuel cell (32) utilizing an improved temperature control system (30) that varies the flow rate of inlet air entering the fuel cell (32) in response to changes in the operating temperature of the fuel cell (32). Consistent with the invention an improved temperature control system (30) is provided that includes a controller (37) that receives an indication of the temperature of the inlet air from a temperature sensor (39) and varies the heat output by at least one heat source (34, 36) to maintain the temperature of the inlet air at a set-point T.sub.inset. The controller (37) also receives an indication of the operating temperature of the fuel cell (32) and varies the flow output by an adjustable air mover (33), within a predetermined range around a set-point F.sub.set, in order to maintain the operating temperature of the fuel cell (32) at a set-point T.sub.opset.

  17. Improvement of the operation rate of medical temperature measuring devices

    NASA Astrophysics Data System (ADS)

    Hotra, O.; Boyko, O.; Zyska, T.

    2014-08-01

    A method of reducing measuring time of temperature measurements of biological objects based on preheating the resistance temperature detector (RTD) up to the temperature close to the temperature to be measured, is proposed. It has been found that at the same measuring time, the preheating allows to decrease the measurement error by a factor of 5 to 45 over the temperature range of 35-41°С. The measurement time is reduced by 1.6-4 times over this range, keeping the same value of the measurement error.

  18. 47 CFR 90.1432 - Conditions for waiver to allow limited and temporary wideband operations in the 700 MHz public...

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... temporary wideband operations in the 700 MHz public safety spectrum. 90.1432 Section 90.1432... and temporary wideband operations in the 700 MHz public safety spectrum. (a) Wideband operations in the 700 MHz Public Safety spectrum. Wideband operations are prohibited in the public safety...

  19. 47 CFR 90.1432 - Conditions for waiver to allow limited and temporary wideband operations in the 700 MHz public...

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... temporary wideband operations in the 700 MHz public safety spectrum. 90.1432 Section 90.1432... and temporary wideband operations in the 700 MHz public safety spectrum. (a) Wideband operations in the 700 MHz Public Safety spectrum. Wideband operations are prohibited in the public safety...

  20. 47 CFR 90.1432 - Conditions for waiver to allow limited and temporary wideband operations in the 700 MHz public...

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... temporary wideband operations in the 700 MHz public safety spectrum. 90.1432 Section 90.1432... and temporary wideband operations in the 700 MHz public safety spectrum. (a) Wideband operations in the 700 MHz Public Safety spectrum. Wideband operations are prohibited in the public safety...

  1. Improved Wide Operating Temperature Range of Li-Ion Cells

    NASA Technical Reports Server (NTRS)

    Smart, Marshall C.; Bugga, Ratnakumar V.

    2013-01-01

    Future NASA missions aimed at exploring the Moon, Mars, and the outer planets require rechargeable batteries that can operate over a wide temperature range (-60 to +60 C) to satisfy the requirements of various applications including landers, rovers, penetrators, CEV, CLV, etc. This work addresses the need for robust rechargeable batteries that can operate well over a wide temperature range. The Department of Energy (DoE) has identified a number of technical barriers associated with the development of Liion rechargeable batteries for PHEVs. For this reason, DoE has interest in the development of advanced electrolytes that will improve performance over a wide range of temperatures, and lead to long life characteristics (5,000 cycles over a 10-year life span). There is also interest in improving the high-voltage stability of these candidate electrolyte systems to enable the operation of up to 5 V with high specific energy cathode materials. Currently, the state-of-the-art lithium-ion system has been demonstrated to operate over a wide range of temperatures (-40 to +40 C); however, the rate capability at the lower temperatures is very poor. In addition, the low-temperature performance typically deteriorates rapidly upon being exposed to high temperatures. A number of electrolyte formulations were developed that incorporate the use of electrolyte additives to improve the high-temperature resilience, low-temperature power capability, and life characteristics of methyl propionate (MP)-based electrolyte solutions. These electrolyte additives include mono-fluoroethylene carbonate (FEC), lithium oxalate, vinylene carbonate (VC), and lithium bis(oxalate borate) (LiBOB), which have previously been shown to result in improved high-temperature resilience of all carbonate-based electrolytes. These MP-based electrolytes with additives have been shown to have improved performance in experiments with MCMB-LiNiCoAlO2 cells.

  2. Low Temperature Operation of a Switching Power Converter

    NASA Technical Reports Server (NTRS)

    Anglada-Sanchez, Carlos R.; Perez-Feliciano, David; Ray, Biswajit

    1997-01-01

    The low temperature operation of a 48 W, 50 kHz, 36/12 V pulse width modulated (PWM) buck de-de power converter designed with standard commercially available components and devices is reported. The efficiency of the converter increased from 85.6% at room temperature (300 K) to 92.0% at liquid nitrogen temperature (77 K). The variation of power MOSFET, diode rectifier, and output filter inductor loss with temperature is discussed. Relevant current, voltage. and power waveforms are also included.

  3. A Proton Channel Allows a Hydrogen Oxidation Catalyst to Operate at a Moderate Overpotential with Water Acting as a Base

    SciTech Connect

    Lense, Sheri J.; Dutta, Arnab; Roberts, John A.; Shaw, Wendy J.

    2014-01-25

    Proton channels facilitate the movement of protons over large distances and are critical in many reactions, from controlling proton delivery in metalloenzymes[1] to moving protons through PEM fuel cells.[2] Hydrogenases are enzymes that use proton channels to deliver protons to or from the enzyme active site to achieve high rates of hydrogen production and oxidation at low overpotentials.[3] The [Ni(PR2NR’2)2]2+ series of complexes, which are functional mimics of the [FeFe]-hydrogenase active site, utilize pendant amines to move the proton to or from the Ni, resulting in some of the fastest synthetic catalysts for hydrogen production and oxidation reported.[4] While intramolecular proton movement has been shown to be facile,[5] deprotonation of hydrogen oxidation catalysts can be a slow step for catalysis.[6] Additionally, a stable H2 adduct (endo-endo) is formed which, if bypassed, could contribute to an overall enhanced rate (Figure 1). A proton channel may aid in addressing these outstanding issues, and the well-studied nature of these catalysts allows them to serve as a platform to investigate the role of a proton channel in solving these problems. To this end we added a second proton relay to this complex, which we demonstrate serves two purposes: we show that the second proton relay facilitates rapid proton transfer, altering the kinetic products formed following H2 addition, and avoiding the low energy endo-endo intermediate. It also aids in lowering the overpotential at which the catalyst operates using water as a base, demonstrating the multi-functional role of a proton channel in molecular catalysts, and possibly in enzymes. This work was supported by the US Department of Energy, Early Career Research Program, Basic Energy Sciences, Chemical Sciences, Geosciences & Biosciences Division and by the Center for Molecular Electrocatalysis, an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Basic Energy Sciences

  4. Dynamic modeling of temperature change in outdoor operated tubular photobioreactors.

    PubMed

    Androga, Dominic Deo; Uyar, Basar; Koku, Harun; Eroglu, Inci

    2017-04-06

    In this study, a one-dimensional transient model was developed to analyze the temperature variation of tubular photobioreactors operated outdoors and the validity of the model was tested by comparing the predictions of the model with the experimental data. The model included the effects of convection and radiative heat exchange on the reactor temperature throughout the day. The temperatures in the reactors increased with increasing solar radiation and air temperatures, and the predicted reactor temperatures corresponded well to the measured experimental values. The heat transferred to the reactor was mainly through radiation: the radiative heat absorbed by the reactor medium, ground radiation, air radiation, and solar (direct and diffuse) radiation, while heat loss was mainly through the heat transfer to the cooling water and forced convection. The amount of heat transferred by reflected radiation and metabolic activities of the bacteria and pump work was negligible. Counter-current cooling was more effective in controlling reactor temperature than co-current cooling. The model developed identifies major heat transfer mechanisms in outdoor operated tubular photobioreactors, and accurately predicts temperature changes in these systems. This is useful in determining cooling duty under transient conditions and scaling up photobioreactors. The photobioreactor design and the thermal modeling were carried out and experimental results obtained for the case study of photofermentative hydrogen production by Rhodobacter capsulatus, but the approach is applicable to photobiological systems that are to be operated under outdoor conditions with significant cooling demands.

  5. Liquid Nitrogen Temperature Operation of a Switching Power Converter

    NASA Technical Reports Server (NTRS)

    Ray, Biswajit; Gerber, Scott S.; Patterson, Richard L.; Myers, Ira T.

    1995-01-01

    The performance of a 42/28 V, 175 W, 50 kHz pulse-width modulated buck dc/dc switching power converter at liquid nitrogen temperature (LNT) is compared with room temperature operation. The power circuit as well as the control circuit of the converter, designed with commercially available components, were operated at LNT and resulted in a slight improvement in converter efficiency. The improvement in power MOSFET operation was offset by deteriorating performance of the output diode rectifier at LNT. Performance of the converter could be further improved at low temperatures by using only power MOSFET's as switches. The use of a resonant topology will further improve the circuit performance by reducing the switching noise and loss.

  6. Nylon coil actuator operating temperature range and stiffness

    NASA Astrophysics Data System (ADS)

    Kianzad, Soheil; Pandit, Milind; Bahi, Addie; Rafie Ravandi, Ali; Ko, Frank; Spinks, Geoffrey M.; Madden, John D. W.

    2015-04-01

    Components in automotive and aerospace applications require a wide temperature range of operation. Newly discovered thermally active Baughman muscle potentially provides affordable and viable solutions for driving mechanical devices by heating them from room temperature, but little is known about their operation below room temperature. We study the mechanical behavior of nylon coil actuators by testing elastic modulus and by investigating tensile stroke as a function of temperature. Loads that range from 35 MPa to 155 MPa were applied. For the nylon used and the coiling conditions, active thermal contraction totals 19.5 % when the temperature is raised from -40 °C to 160 °C. The thermal contraction observed from -40 °C to 20°C is only ~2 %, whereas between 100 and 160 °C the contraction is 10 %. A marked increase in thermal contraction is occurs in the vicinity of the glass transition temperature (~ 45°C). The elastic modulus drops as temperature increases, from ~155 MPa at - 40 °C to 35 MPa at 200 °C. Interestingly the drop in active contraction with increasing load is small and much less than might be expected given the temperature dependence of modulus.

  7. The Effect of Operating Temperature on De-pressurized Conduction Cooldown for a High Temperature Reactor

    SciTech Connect

    Mays, Brian E.; Woaye-Hune, Antony; Simoneau, Jan-Patrice; Gabeloteau, Thierry; Lefort, Frederic; Haque, Hamidul; Lommers, Lewis

    2004-07-01

    Passive decay heat removal through conduction and radiation (i.e., conduction cooldown) is a key feature of the high temperature reactor (HTR) designs currently being developed. Several evaluations of conduction cooldown performance have been performed previously for current HTR designs with core outlet temperatures of around 850 degrees Celsius. However, additional work is required to assess the impact of adopting alternate operating conditions, such as those of the Generation IV Very High Temperature Reactor (VHTR) concept (e.g., 1000 degrees Celsius outlet temperature). This study examines the effect of reactor operating temperature on de-pressurized conduction cooldown results. Numerical simulations of a de-pressurized conduction cooldown event for a prismatic block HTR are performed using STAR-CD{sup R}, a commercially available computational-fluid dynamics/ heat-transfer code. In parallel, calculations are performed using THERMIX, a code used in the German HTR program. These calculations first are performed for a design based on the Gas Turbine-Modular Helium Reactor (GT-MHR) configuration with an outlet temperature of 850 degrees Celsius. The calculations then are extended to VHTR operating conditions to assess the thermal consequences of higher outlet temperatures, and potentially lower inlet temperatures, on the fuel and reactor vessel. Increasing the outlet temperature to VHTR conditions (approximately 1000 degrees Celsius) results in a relatively small increase in the peak fuel temperature. A more significant effect results from changing the inlet temperature, since this change affects a much larger volume of graphite in the reactor. In all cases, changes in the operating temperature primarily influence only the early phases of the transient. The long-term behavior-governed by the quasi-steady-state balance of the decay heat power, the geometry, and the heat transport properties of the system-is less sensitive to such changes. Therefore, the significance

  8. Modeling Shasta Dam operations to regulate temperatures for Chinook salmon under extreme climate and climate change

    NASA Astrophysics Data System (ADS)

    Dai, A.; Saito, L.; Sapin, J. R.; Rajagopalan, B.; Hanna, R. B.; Kauneckis, D. L.

    2014-12-01

    Chinook salmon populations have declined significantly after the construction of Shasta Dam on the Sacramento River in 1945 prevented them from spawning in the cold waters upstream. In 1994, the winter-run Chinook were listed under the Endangered Species Act and 3 years later the US Bureau of Reclamation began operating a temperature control device (TCD) on the dam that allows for selective withdrawal for downstream temperature control to promote salmon spawning while also maximizing power generation. However, dam operators are responsible to other interests that depend on the reservoir for water such as agriculture, municipalities, industry, and recreation. An increase in temperatures due to climate change may place additional strain on the ability of dam operations to maintain spawning habitat for salmon downstream of the dam. We examined the capability of Shasta Dam to regulate downstream temperatures under extreme climates and climate change by using stochastically generated streamflow, stream temperature, and weather inputs with a two-dimensional CE-QUAL-W2 model under several operational options. Operation performance was evaluated using degree days and cold pool volume (volume of water below a temperature threshold). Model results indicated that a generalized operations release schedule, in which release elevations varied over the year to match downstream temperature targets, performed best overall in meeting temperature targets while preserving cold pool volume. Releasing all water out the bottom throughout the year tended to meet temperature targets at the expense of depleting the cold pool, and releasing all water out uppermost gates preserved the cold pool, but released water that was too warm during the critical spawning period. With higher air temperatures due to climate change, both degree day and cold pool volume metrics were worse than baseline conditions, which suggests that Chinook salmon may be more negatively affected under climate change.

  9. 980nm diode laser pump modules operating at high temperature

    NASA Astrophysics Data System (ADS)

    Campbell, Jenna; Semenic, Tadej; Leisher, Paul; Bhunia, Avijit; Mashanovitch, Milan; Renner, Daniel

    2016-03-01

    Existing thermal management technologies for diode laser pumps place a significant load on the size, weight and power consumption of High Power Solid State and Fiber Laser systems, thus making current laser systems very large, heavy, and inefficient in many important practical applications. This problem is being addressed by the team formed by Freedom Photonics and Teledyne Scientific through the development of novel high power laser chip array architectures that can operate with high efficiency when cooled with coolants at temperatures higher than 50 degrees Celsius and also the development of an advanced thermal management system for efficient heat extraction from the laser chip array. This paper will present experimental results for the optical, electrical and thermal characteristics of 980 nm diode laser pump modules operating effectively with liquid coolant at temperatures above 50 degrees Celsius, showing a very small change in performance as the operating temperature increases from 20 to 50 degrees Celsius. These pump modules can achieve output power of many Watts per array lasing element with an operating Wall-Plug-Efficiency (WPE) of >55% at elevated coolant temperatures. The paper will also discuss the technical approach that has enabled this high level of pump module performance and opportunities for further improvement.

  10. High Operating Temperature Liquid Metal Heat Transfer Fluids (Fact Sheet)

    SciTech Connect

    Not Available

    2012-12-01

    The University of California, Los Angeles, the University of California, Berkeley, and Yale University is one of the 2012 SunShot CSP R&D awardees for their Multidisciplinary University Research Initiative (MURI): High Operating Temperature (HOT) Fluids. This fact sheet explains the motivation, description, and impact of the project.

  11. Temperature dependences of mechanisms responsible for the water-vapor continuum absorption. I. Far wings of allowed lines.

    PubMed

    Ma, Q; Tipping, R H; Leforestier, C

    2008-03-28

    It is well known that the water-vapor continuum plays an important role in the radiative balance in the Earth's atmosphere. This was first discovered by Elsasser almost 70 years ago, and since that time there has been a large body of work, both experimental and theoretical, on this topic. It has been experimentally shown that for ambient atmospheric conditions, the continuum absorption scales quadratically with the H(2)O number density and has a strong, negative temperature dependence (T dependence). Over the years, there have been three different theoretical mechanisms postulated: Far wings of allowed transitions, water dimers, and collision-induced absorption. Despite the improvements in experimental data, at present there is no consensus on which mechanism is primarily responsible for the absorption. The first mechanism proposed was the accumulation of the far-wing absorption of the strong allowed transitions. Later, absorption by water dimers was proposed and this mechanism provides a qualitative explanation for the strong, negative T dependence. Recently, some atmospheric modelers have proposed that collision-induced absorption is one of the major contributors. However, based on improvements in the theoretical calculation of accurate far-wing line shapes, ab initio dimer calculations, and theoretical collision-induced absorptions, it is now generally accepted that the dominant mechanism for the absorption in the infrared (IR) windows is that due to the far wings. Whether this is true for other spectral regions is not presently established. Although all these three mechanisms have a negative T dependence, their T dependences will be characterized by individual features. To analyze the characteristics of the latter will enable one to assess their roles with more certainty. In this paper, we present a detailed study of the T dependence of the far-wing absorption mechanism. We will then compare our theoretical calculations with the most recent and accurate

  12. Solid oxide fuel cell operable over wide temperature range

    DOEpatents

    Baozhen, Li; Ruka, Roswell J.; Singhal, Subhash C.

    2001-01-01

    Solid oxide fuel cells having improved low-temperature operation are disclosed. In one embodiment, an interfacial layer of terbia-stabilized zirconia is located between the air electrode and electrolyte of the solid oxide fuel cell. The interfacial layer provides a barrier which controls interaction between the air electrode and electrolyte. The interfacial layer also reduces polarization loss through the reduction of the air electrode/electrolyte interfacial electrical resistance. In another embodiment, the solid oxide fuel cell comprises a scandia-stabilized zirconia electrolyte having high electrical conductivity. The scandia-stabilized zirconia electrolyte may be provided as a very thin layer in order to reduce resistance. The scandia-stabilized electrolyte is preferably used in combination with the terbia-stabilized interfacial layer. The solid oxide fuel cells are operable over wider temperature ranges and wider temperature gradients in comparison with conventional fuel cells.

  13. Compassionate Allowances

    MedlinePlus

    Skip to content Social Security Search Menu Languages Sign in / up Compassionate Allowances Featured Items Compassionate Allowances Conditions CAL conditions are selected using information received ...

  14. Evaluation of Silicon-on-Insulator HTOP-01 Operational Amplifier for Wide Temperature Operation

    NASA Technical Reports Server (NTRS)

    Patterson, Richard; Hammoud, Ahmad; Elbuluk, Malik

    2008-01-01

    Electronics capable of operation under extreme temperatures are required in many of NASA space exploration missions. Aerospace and military applications, as well as some terrestrial industries constitute environments where electronic systems are anticipated to be exposed to extreme temperatures and wide-range thermal swings. Electronics that are able to withstand and operate efficiently in such harsh environments would simplify, if not eliminate, traditional thermal control elements and their associated structures for proper ambient operation. As a result, overall system mass would be reduced, design would be simplified, and reliability would be improved. Electronic parts that are built utilizing silicon-on-insulator (SOI) technology are known to offer better radiation-tolerance compared to their conventional silicon counterparts, provide faster switching, and consume less power. They also exhibit reduced leakage current and, thus, they are often tailored for high temperature operation. These attributes make SOI-based devices suitable for use in harsh environments where extreme temperatures and wide thermal swings are anticipated. A new operational amplifier, based on silicon-on-insulator technology and geared for high temperature well-logging applications, was recently introduced by Honeywell Corporation. This HTOP-01 dual precision operational amplifier is a low power device, operates on a single supply, and has an internal oscillator and an external clocking option [1]. It is rated for operation from -55 C to +225 C with a maximum output current capability of 50 mA. The amplifier chip is designed as a 14-pin, hermetically-sealed device in a ceramic package. Table I shows some of the device manufacturer s specifications.

  15. Amplifier circuit operable over a wide temperature range

    DOEpatents

    Kelly, Ronald D.; Cannon, William L.

    1979-01-01

    An amplifier circuit having stable performance characteristics over a wide temperature range from approximately 0.degree. C up to as high as approximately 500.degree. C, such as might be encountered in a geothermal borehole. The amplifier utilizes ceramic vacuum tubes connected in directly coupled differential amplifier pairs having a common power supply and a cathode follower output stage. In an alternate embodiment, for operation up to 500.degree. C, positive and negative power supplies are utilized to provide improved gain characteristics, and all electrical connections are made by welding. Resistor elements in this version of the invention are specially heat treated to improve their stability with temperature.

  16. Method of low temperature operation of an electrochemical cell array

    DOEpatents

    Singh, Prabhakar; Ruka, Roswell J.; Bratton, Raymond J.

    1994-01-01

    In the method of operating an electrochemical cell generator apparatus containing a generator chamber (20) containing an array of cells (12) having interior and exterior electrodes with solid electrolyte between the electrodes, where a hot gas (F) contacts the outside of the cells (12) and the generating chamber normally operates at over 850.degree. C., where N.sub.2 gas is fed to contact the interior electrode of the cells (12) in any case when the generating chamber (20) temperature drops for whatever reason to within the range of from 550.degree. C. to 800.degree. C., to eliminate cracking within the cells (12).

  17. Method of low temperature operation of an electrochemical cell array

    DOEpatents

    Singh, P.; Ruka, R.J.; Bratton, R.J.

    1994-04-26

    A method is described for operating an electrochemical cell generator apparatus containing a generator chamber containing an array of cells having interior and exterior electrodes with solid electrolyte between the electrodes, where a hot gas contacts the outside of the cells and the generating chamber normally operates at over 850 C, where N[sub 2] gas is fed to contact the interior electrode of the cells in any case when the generating chamber temperature drops for whatever reason to within the range of from 550 C to 800 C, to eliminate cracking within the cells. 2 figures.

  18. Small-Scale Mechanical Testing on Proton Beam-Irradiated 304 SS from Room Temperature to Reactor Operation Temperature

    NASA Astrophysics Data System (ADS)

    Vo, H.; Reichardt, A.; Howard, C.; Abad, M. D.; Kaoumi, D.; Chou, P.; Hosemann, P.

    2015-12-01

    Austenitic stainless steels are common structural components in light water reactors. Because reactor components are subjected to harsh conditions such as high operating temperatures and neutron radiation, they can undergo irradiation-induced embrittlement and related failure, which compromises reliable operation. Small-scale mechanical testing has seen widespread use as a testing method for both ion- and reactor-irradiated materials because it allows access to the mechanical properties of the ion beam-irradiated region, and for safe handling of a small amount of activated material. In this study, nanoindentation and microcompression testing were performed on unirradiated and 10 dpa proton-irradiated 304 SS, from 25°C to 300°C. Increases in yield stress (YS), critical resolved shear stress (CRSS) and hardness ( H) were seen in the irradiated region relative to the unirradiated region. Relationships between H, YS, and CRSS of irradiated and unirradiated materials are discussed over this temperature range.

  19. 42 CFR 413.139 - Depreciation: Optional allowance for depreciation based on a percentage of operating costs.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... is determined. (c) Application. If a provider has inadequate historical cost records for pre-1966... either has no historical cost records or has incomplete records, the determination of historical cost may... based on a percentage of operating costs. 413.139 Section 413.139 Public Health CENTERS FOR...

  20. Performance of High Temperature Operational Amplifier, Type LM2904WH, under Extreme Temperatures

    NASA Technical Reports Server (NTRS)

    Patterson, Richard; Hammoud, Ahmad; Elbuluk, Malik

    2008-01-01

    Operation of electronic parts and circuits under extreme temperatures is anticipated in NASA space exploration missions as well as terrestrial applications. Exposure of electronics to extreme temperatures and wide-range thermal swings greatly affects their performance via induced changes in the semiconductor material properties, packaging and interconnects, or due to incompatibility issues between interfaces that result from thermal expansion/contraction mismatch. Electronics that are designed to withstand operation and perform efficiently in extreme temperatures would mitigate risks for failure due to thermal stresses and, therefore, improve system reliability. In addition, they contribute to reducing system size and weight, simplifying its design, and reducing development cost through the elimination of otherwise required thermal control elements for proper ambient operation. A large DC voltage gain (100 dB) operational amplifier with a maximum junction temperature of 150 C was recently introduced by STMicroelectronics [1]. This LM2904WH chip comes in a plastic package and is designed specifically for automotive and industrial control systems. It operates from a single power supply over a wide range of voltages, and it consists of two independent, high gain, internally frequency compensated operational amplifiers. Table I shows some of the device manufacturer s specifications.

  1. Performance of Wide Operating Temperature Range Electrolytes in Quallion Prototype Li-Ion Cells

    NASA Technical Reports Server (NTRS)

    Smart, M. C.; Ratnakumar, B. V.; Tomcsi, M. R.; Nagata, M.; Visco, V.; Tsukamoto, H.

    2010-01-01

    For a number of applications, there is a continued interest in the development of rechargeable lithium-based batteries that can effectively operate over a wide temperature range (i.e., -40 to +70 deg C). These applications include powering future planetary rovers for NASA, enabling the next generation of automotive batteries for DOE, and supporting many DOD applications. Li-ion technology has been demonstrated to have good performance over a reasonably wide temperature range with many systems; however, there is still a desire to improve the low temperature rate capacity as well as the high temperature resilience. In the current study, we would like to present recent results obtained with prototype Li-Ion cells (manufactured by Quallion, LLC) which include various wide operating temperature range electrolytes developed by both JPL and Quallion. To demonstrate the viability of the technology, a number of performance tests were carried out, including: (a) discharge rate characterization over a wide temperature range (down to -60 deg C) using various rates (up to 20C rates), (b) discharge rate characterization at low temperatures with low temperature charging, (c) variable temperature cycling over a wide temperature range (-40 to +70 deg C), and (d) cycling at high temperature (50 deg C). As will be discussed, impressive rate capability was observed at low temperatures with many systems, as well as good resilience to high temperature cycling. To augment the performance testing on the prototype cells, a number of experimental three electrodes cells were fabricated (including Li reference electrodes) to allow the determination of the lithium kinetics of the respective electrodes and interfacial properties as a function of temperatures.

  2. Temperature mapping of operating nanoscale devices by scanning probe thermometry

    NASA Astrophysics Data System (ADS)

    Menges, Fabian; Mensch, Philipp; Schmid, Heinz; Riel, Heike; Stemmer, Andreas; Gotsmann, Bernd

    2016-03-01

    Imaging temperature fields at the nanoscale is a central challenge in various areas of science and technology. Nanoscopic hotspots, such as those observed in integrated circuits or plasmonic nanostructures, can be used to modify the local properties of matter, govern physical processes, activate chemical reactions and trigger biological mechanisms in living organisms. The development of high-resolution thermometry techniques is essential for understanding local thermal non-equilibrium processes during the operation of numerous nanoscale devices. Here we present a technique to map temperature fields using a scanning thermal microscope. Our method permits the elimination of tip-sample contact-related artefacts, a major hurdle that so far has limited the use of scanning probe microscopy for nanoscale thermometry. We map local Peltier effects at the metal-semiconductor contacts to an indium arsenide nanowire and self-heating of a metal interconnect with 7 mK and sub-10 nm spatial temperature resolution.

  3. Temperature mapping of operating nanoscale devices by scanning probe thermometry

    PubMed Central

    Menges, Fabian; Mensch, Philipp; Schmid, Heinz; Riel, Heike; Stemmer, Andreas; Gotsmann, Bernd

    2016-01-01

    Imaging temperature fields at the nanoscale is a central challenge in various areas of science and technology. Nanoscopic hotspots, such as those observed in integrated circuits or plasmonic nanostructures, can be used to modify the local properties of matter, govern physical processes, activate chemical reactions and trigger biological mechanisms in living organisms. The development of high-resolution thermometry techniques is essential for understanding local thermal non-equilibrium processes during the operation of numerous nanoscale devices. Here we present a technique to map temperature fields using a scanning thermal microscope. Our method permits the elimination of tip–sample contact-related artefacts, a major hurdle that so far has limited the use of scanning probe microscopy for nanoscale thermometry. We map local Peltier effects at the metal–semiconductor contacts to an indium arsenide nanowire and self-heating of a metal interconnect with 7 mK and sub-10 nm spatial temperature resolution. PMID:26936427

  4. Progress report on the design of a varying temperature irradiation experiment for operation in HFIR

    SciTech Connect

    Qualls, A.L.; Muroga, T.

    1997-04-01

    The purpose of this experiment is to determine effects of temperature variation during irradiation on microstructure and mechanical properties of potential fusion reactor structural materials. A varying temperature irradiation experiment is being performed under the framework of the Japan-USA Program of Irradiation Tests for fusion Research (JUPITER) to study the effects of temperature variation on the microstructure and mechanical properties of candidate fusion reactor structural materials. An irradiation capsule has been designed for operation in the High Flux Isotope Reactor at Oak Ridge National Laboratory that will allow four sets of metallurgical test specimens to be irradiated to exposure levels ranging from 5 to 10 dpa. Two sets of specimens will be irradiated at constant temperature of 500{degrees}C and 350{degrees}C. Matching specimen sets will be irradiated to similar exposure levels, with 10% of the exposure to occur at reduced temperatures of 300{degrees}C and 200{degrees}C.

  5. Effect of Temperature on the Aging rate of Li Ion Battery Operating above Room Temperature

    PubMed Central

    Leng, Feng; Tan, Cher Ming; Pecht, Michael

    2015-01-01

    Temperature is known to have a significant impact on the performance, safety, and cycle lifetime of lithium-ion batteries (LiB). However, the comprehensive effects of temperature on the cyclic aging rate of LiB have yet to be found. We use an electrochemistry-based model (ECBE) here to measure the effects on the aging behavior of cycled LiB operating within the temperature range of 25 °C to 55 °C. The increasing degradation rate of the maximum charge storage of LiB during cycling at elevated temperature is found to relate mainly to the degradations at the electrodes, and that the degradation of LCO cathode is larger than graphite anode at elevated temperature. In particular, the formation and modification of the surface films on the electrodes as well as structural/phase changes of the LCO electrode, as reported in the literatures, are found to be the main contributors to the increasing degradation rate of the maximum charge storage of LiB with temperature for the specific operating temperature range. Larger increases in the Warburg elements and cell impedance are also found with cycling at higher temperature, but they do not seriously affect the state of health (SoH) of LiB as shown in this work. PMID:26245922

  6. Effect of Temperature on the Aging rate of Li Ion Battery Operating above Room Temperature.

    PubMed

    Leng, Feng; Tan, Cher Ming; Pecht, Michael

    2015-08-06

    Temperature is known to have a significant impact on the performance, safety, and cycle lifetime of lithium-ion batteries (LiB). However, the comprehensive effects of temperature on the cyclic aging rate of LiB have yet to be found. We use an electrochemistry-based model (ECBE) here to measure the effects on the aging behavior of cycled LiB operating within the temperature range of 25 °C to 55 °C. The increasing degradation rate of the maximum charge storage of LiB during cycling at elevated temperature is found to relate mainly to the degradations at the electrodes, and that the degradation of LCO cathode is larger than graphite anode at elevated temperature. In particular, the formation and modification of the surface films on the electrodes as well as structural/phase changes of the LCO electrode, as reported in the literatures, are found to be the main contributors to the increasing degradation rate of the maximum charge storage of LiB with temperature for the specific operating temperature range. Larger increases in the Warburg elements and cell impedance are also found with cycling at higher temperature, but they do not seriously affect the state of health (SoH) of LiB as shown in this work.

  7. Temperature dependent operation of PSAPD-based compact gamma camera for SPECT imaging

    PubMed Central

    Kim, Sangtaek; McClish, Mickel; Alhassen, Fares; Seo, Youngho; Shah, Kanai S.; Gould, Robert G.

    2011-01-01

    We investigated the dependence of image quality on the temperature of a position sensitive avalanche photodiode (PSAPD)-based small animal single photon emission computed tomography (SPECT) gamma camera with a CsI:Tl scintillator. Currently, nitrogen gas cooling is preferred to operate PSAPDs in order to minimize the dark current shot noise. Being able to operate a PSAPD at a relatively high temperature (e.g., 5 °C) would allow a more compact and simple cooling system for the PSAPD. In our investigation, the temperature of the PSAPD was controlled by varying the flow of cold nitrogen gas through the PSAPD module and varied from −40 °C to 20 °C. Three experiments were performed to demonstrate the performance variation over this temperature range. The point spread function (PSF) of the gamma camera was measured at various temperatures, showing variation of full-width-half-maximum (FWHM) of the PSF. In addition, a 99mTc-pertechnetate (140 keV) flood source was imaged and the visibility of the scintillator segmentation (16×16 array, 8 mm × 8 mm area, 400 μm pixel size) at different temperatures was evaluated. Comparison of image quality was made at −25 °C and 5 °C using a mouse heart phantom filled with an aqueous solution of 99mTc-pertechnetate and imaged using a 0.5 mm pinhole collimator made of tungsten. The reconstructed image quality of the mouse heart phantom at 5 °C degraded in comparision to the reconstructed image quality at −25 °C. However, the defect and structure of the mouse heart phantom were clearly observed, showing the feasibility of operating PSAPDs for SPECT imaging at 5 °C, a temperature that would not need the nitrogen cooling. All PSAPD evaluations were conducted with an applied bias voltage that allowed the highest gain at a given temperature. PMID:24465051

  8. 40 CFR 63.1185 - How do I establish the average operating temperature of an incinerator?

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... operating temperature of an incinerator? 63.1185 Section 63.1185 Protection of Environment ENVIRONMENTAL... operating temperature of an incinerator? (a) During the performance test, you must establish the average operating temperature of an incinerator as follows: (1) Continuously measure the operating temperature...

  9. 40 CFR 63.1185 - How do I establish the average operating temperature of an incinerator?

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... operating temperature of an incinerator? 63.1185 Section 63.1185 Protection of Environment ENVIRONMENTAL... operating temperature of an incinerator? (a) During the performance test, you must establish the average operating temperature of an incinerator as follows: (1) Continuously measure the operating temperature...

  10. 40 CFR 63.1185 - How do I establish the average operating temperature of an incinerator?

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... operating temperature of an incinerator? 63.1185 Section 63.1185 Protection of Environment ENVIRONMENTAL... operating temperature of an incinerator? (a) During the performance test, you must establish the average operating temperature of an incinerator as follows: (1) Continuously measure the operating temperature...

  11. 40 CFR 63.1185 - How do I establish the average operating temperature of an incinerator?

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... operating temperature of an incinerator? 63.1185 Section 63.1185 Protection of Environment ENVIRONMENTAL... operating temperature of an incinerator? (a) During the performance test, you must establish the average operating temperature of an incinerator as follows: (1) Continuously measure the operating temperature...

  12. 40 CFR 63.1185 - How do I establish the average operating temperature of an incinerator?

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... operating temperature of an incinerator? 63.1185 Section 63.1185 Protection of Environment ENVIRONMENTAL... operating temperature of an incinerator? (a) During the performance test, you must establish the average operating temperature of an incinerator as follows: (1) Continuously measure the operating temperature...

  13. SY-101 Rapid Transfer Project Low Temperature Operations Review and Recommendations to Support Lower Temperature Limits

    SciTech Connect

    HICKMAN, G.L.

    2000-01-10

    The lower temperature limit for the 241 SY-101 RAPID transfer project is currently set at 20 F Based on the analysis and recommendations in this document this limit can be lowered to 0 F. Analysis of all structures systems and components (SSCs) indicate that a reduction in operating temperature may be achieved with minor modifications to field-installed equipment. Following implementation of these changes it is recommended that the system requirements be amended to specify a temperature range for transfer or back dilute evolutions of 0 F to 100 F.

  14. Li/CFx Cells Optimized for Low-Temperature Operation

    NASA Technical Reports Server (NTRS)

    Smart, Marshall C.; Whitacre, Jay F.; Bugga, Ratnakumar V.; Prakash, G. K. Surya; Bhalla, Pooja; Smith, Kiah

    2009-01-01

    Some developments reported in prior NASA Tech Briefs articles on primary electrochemical power cells containing lithium anodes and fluorinated carbonaceous (CFx) cathodes have been combined to yield a product line of cells optimized for relatively-high-current operation at low temperatures at which commercial lithium-based cells become useless. These developments have involved modifications of the chemistry of commercial Li/CFx cells and batteries, which are not suitable for high-current and low-temperature applications because they are current-limited and their maximum discharge rates decrease with decreasing temperature. One of two developments that constitute the present combination is, itself, a combination of developments: (1) the use of sub-fluorinated carbonaceous (CFx wherein x<1) cathode material, (2) making the cathodes thinner than in most commercial units, and (3) using non-aqueous electrolytes formulated especially to enhance low-temperature performance. This combination of developments was described in more detail in High-Energy-Density, Low- Temperature Li/CFx Primary Cells (NPO-43219), NASA Tech Briefs, Vol. 31, No. 7 (July 2007), page 43. The other development included in the present combination is the use of an anion receptor as an electrolyte additive, as described in the immediately preceding article, "Additive for Low-Temperature Operation of Li-(CF)n Cells" (NPO- 43579). A typical cell according to the present combination of developments contains an anion-receptor additive solvated in an electrolyte that comprises LiBF4 dissolved at a concentration of 0.5 M in a mixture of four volume parts of 1,2 dimethoxyethane with one volume part of propylene carbonate. The proportion, x, of fluorine in the cathode in such a cell lies between 0.5 and 0.9. The best of such cells fabricated to date have exhibited discharge capacities as large as 0.6 A h per gram at a temperature of 50 C when discharged at a rate of C/5 (where C is the magnitude of the

  15. Infrared negative luminescent devices and higher operating temperature detectors

    NASA Astrophysics Data System (ADS)

    Nash, G. R.; Gordon, N. T.; Hall, D. J.; Ashby, M. K.; Little, J. C.; Masterton, G.; Hails, J. E.; Giess, J.; Haworth, L.; Emeny, M. T.; Ashley, T.

    2004-01-01

    Infrared LEDs and negative luminescent devices, where less light is emitted than in equilibrium, have been attracting an increasing amount of interest recently. They have a variety of applications, including as a ‘source’ of IR radiation for gas sensing; radiation shielding for, and non-uniformity correction of, high sensitivity staring infrared detectors; and dynamic infrared scene projection. Similarly, infrared (IR) detectors are used in arrays for thermal imaging and, discretely, in applications such as gas sensing. Multi-layer heterostructure epitaxy enables the growth of both types of device using designs in which the electronic processes can be precisely controlled and techniques such as carrier exclusion and extraction can be implemented. This enables detectors to be made which offer good performance at higher than normal operating temperatures, and efficient negative luminescent devices to be made which simulate a range of effective temperatures whilst operating uncooled. In both cases, however, additional performance benefits can be achieved by integrating optical concentrators around the diodes to reduce the volume of semiconductor material, and so minimise the thermally activated generation-recombination processes which compete with radiative mechanisms. The integrated concentrators are in the form of Winston cones, which can be formed using an iterative dry etch process involving methane/hydrogen and oxygen. We present results on negative luminescence in the mid- and long-IR wavebands, from devices made from indium antimonide and mercury cadmium telluride, where the aim is sizes greater than 1 cm×1 cm. We also discuss progress on, and the potential for, operating temperature and/or sensitivity improvement of detectors, where very high-performance imaging is anticipated from systems which require no mechanical cooling.

  16. Infrared negative luminescent devices and higher operating temperature detectors

    NASA Astrophysics Data System (ADS)

    Nash, Geoff R.; Gordon, Neil T.; Hall, David J.; Little, J. Chris; Masterton, G.; Hails, J. E.; Giess, J.; Haworth, L.; Emeny, Martin T.; Ashley, Tim

    2004-02-01

    Infrared LEDs and negative luminescent devices, where less light is emitted than in equilibrium, have been attracting an increasing amount of interest recently. They have a variety of applications, including as a ‘source" of IR radiation for gas sensing; radiation shielding for and non-uniformity correction of high sensitivity starring infrared detectors; and dynamic infrared scene projection. Similarly, IR detectors are used in arrays for thermal imaging and, discretely, in applications such as gas sensing. Multi-layer heterostructure epitaxy enables the growth of both types of device using designs in which the electronic processes can be precisely controlled and techniques such as carrier exclusion and extraction can be implemented. This enables detectors to be made which offer good performance at higher than normal operating temperatures, and efficient negative luminescent devices to be made which simulate a range of effective temperatures whilst operating uncooled. In both cases, however, additional performance benefits can be achieved by integrating optical concentrators around the diodes to reduce the volume of semiconductor material, and so minimise the thermally activated generation-recombination processes which compete with radiative mechanisms. The integrated concentrators are in the form of Winston cones, which can be formed using an iterative dry etch process involving methane/hydrogen and oxygen. We will present results on negative luminescence in the mid and long IR wavebands, from devices made from indium antimonide and mercury cadmium telluride, where the aim is sizes greater than 1cm x 1cm. We will also discuss progress on, and the potential for, operating temperature and/or sensitivity improvement of detectors, where very higher performance imaging is anticipated from systems which require no mechanical cooling.

  17. Infrared Negative Luminescent Devices and Higher Operating Temperature Detectors

    NASA Astrophysics Data System (ADS)

    Ashley, Tim

    2003-03-01

    Infrared LEDs and negative luminescent devices, where less light is emitted than in equilibrium, have been attracting an increasing amount of interest recently. They have a variety of applications, including as a source' of IR radiation for gas sensing; radiation shielding for and non-uniformity correction of high sensitivity starring infrared detectors; and dynamic infrared scene projection. Similarly, IR detectors are used in arrays for thermal imaging and, discretely, in applications such as gas sensing. Multi-layer heterostructure epitaxy enables the growth of both types of device using designs in which the electronic processes can be precisely controlled and techniques such as carrier exclusion and extraction can be implemented. This enables detectors to be made which offer good performance at higher than normal operating temperatures, and efficient negative luminescent devices to be made which simulate a range of effective temperatures whilst operating uncooled. In both cases, however, additional performance benefits can be achieved by integrating optical concentrators around the diodes to reduce the volume of semiconductor material, and so minimise the thermally activated generation-recombination processes which compete with radiative mechanisms. The integrated concentrators are in the form of Winston cones, which can be formed using an iterative dry etch process involving methane/hydrogen and oxygen. We will present results on negative luminescence in the mid and long IR wavebands, from devices made from indium antimonide and mercury cadmium telluride, where the aim is sizes greater than 1cm x 1cm. We will also discuss progress on, and the potential for, operating temperature and/or sensitivity improvement of detectors, where very high performance imaging is anticipated from systems which require no mechanical cooling.

  18. Operation and design selection of high temperature superconducting magnetic bearings

    NASA Astrophysics Data System (ADS)

    Werfel, F. N.; Floegel-Delor, U.; Riedel, T.; Rothfeld, R.; Wippich, D.; Goebel, B.

    2004-10-01

    Axial and radial high temperature superconducting (HTS) magnetic bearings are evaluated by their parameters. Journal bearings possess advantages over thrust bearings. High magnetic gradients in a multi-pole permanent magnet (PM) configuration, the surrounding melt textured YBCO stator and adequate designs are the key features for increasing the overall bearing stiffness. The gap distance between rotor and stator determines the specific forces and has a strong impact on the PM rotor design. We report on the designing, building and measuring of a 200 mm prototype 100 kg HTS bearing with an encapsulated and thermally insulated melt textured YBCO ring stator. The encapsulation requires a magnetically large-gap (4-5 mm) operation but reduces the cryogenic effort substantially. The bearing requires 3 l of LN2 for cooling down, and about 0.2 l LN2 h-1 under operation. This is a dramatic improvement of the efficiency and in the practical usage of HTS magnetic bearings.

  19. Mathematical modeling of forest canopy ignition by the Tunguska meteorite with allowance for the dual temperature of the medium

    SciTech Connect

    Grishin, A.M.; Perminov, V.A. )

    1992-12-01

    The ignition of the forest canopy during the Tunguska event is examined by using a mathematical model of forest fires. The dimensions of the ignition zone for fixed explosion energies are determined for different parameters of the forest canopy. Based on mathematical experiments, the explosion energy that agrees best with the available data is determined. The temperature fields and the velocities and concentrations of the gas phase components are determined for different points in time. 8 refs.

  20. High performance shape memory effect in nitinol wire for actuators with increased operating temperature range

    NASA Astrophysics Data System (ADS)

    Casati, Riccardo; Biffi, Carlo Alberto; Vedani, Maurizio; Tuissi, Ausonio

    2014-07-01

    In this research, the high performance shape memory effect (HP-SME) is experimented on a shape memory NiTi wire, with austenite finish temperature higher than room temperature. The HP-SME consists in the thermal cycling of stress induced martensite and it allows achieving mechanical work higher than that produced by conventional shape memory actuators based on the heating/cooling of detwinned martensite. The Nitinol wire was able to recover about 5.5% of deformation under a stress of 600 MPa and to withstand about 5000 cycles before failure. HP-SME path increased the operating temperature of the shape memory actuator wire. Functioning temperatures higher than 100°C was reached.

  1. Towards an operational soil temperature product for Norway

    NASA Astrophysics Data System (ADS)

    Etzelmüller, B.; Westermann, S.; Gisnås, K.; Schuler, T.

    2012-12-01

    In this century, thawing of permafrost is expected to occur in large areas due to climate change, which may become a trigger for climatic feedback mechanisms on the local to global scale. While it is not feasible to cover the vast permafrost areas by ground-based monitoring of soil temperatures in boreholes, wealth of novel multi-sensor-multi-source data could be exploited to assess the thermal ground conditions on large scales. In Norway, a wide range of permafrost conditions occurs - from mountain permafrost over organic-rich wetlands to high-arctic permafrost in Svalbard. Furthermore, gridded data sets from various sources are available so that it is a well-suited test region to evaluate and benchmark the performance of various modeling approaches. While soil temperatures can be modeled using Fourier's law of heat conduction, it is crucial to drive such models by accurate time series of the key input variables at suitable spatial and temporal resolutions. For soil thermal models, these are land surface temperature, snow depth and soil and snow thermal properties. We present a framework for transient and distributed modeling the ground thermal regime in Norway, CryoGRID 2.0. In the model, the subsurface heat flow is treated in terms of 1D heat conduction using the land or snow surface temperature as upper boundary condition. The model features a dynamical representation of the snow cover and explicitly accounts for the heat flux through the snow pack. The model is driven by operationally gridded data of daily air temperature and snow depth available at http://senorge.no. These datasets are available from 1957 to present-day at a spatial resolution of 1 km. The spatial distributions of ground thermal properties (e.g. thermal conductivity) and surface cover are derived from geological maps, borehole measurements and remote sensing data. We present model runs from South Norway highlighting the capacity of the approach to simulate permafrost distribution and duration

  2. Geostationary Operational Environmental Satellite (GOES) Gyro Temperature Model

    NASA Technical Reports Server (NTRS)

    Rowe, J. N.; Noonan, C. H.; Garrick, J.

    1996-01-01

    The geostationary Operational Environmental Satellite (GOES) 1/M series of spacecraft are geostationary weather satellites that use the latest in weather imaging technology. The inertial reference unit package onboard consists of three gyroscopes measuring angular velocity along each of the spacecraft's body axes. This digital integrating rate assembly (DIRA) is calibrated and used to maintain spacecraft attitude during orbital delta-V maneuvers. During the early orbit support of GOES-8 (April 1994), the gyro drift rate biases exhibited a large dependency on gyro temperature. This complicated the calibration and introduced errors into the attitude during delta-V maneuvers. Following GOES-8, a model of the DIRA temperature and drift rate bias variation was developed for GOES-9 (May 1995). This model was used to project a value of the DIRA bias to use during the orbital delta-V maneuvers based on the bias change observed as the DIRA warmed up during the calibration. The model also optimizes the yaw reorientation necessary to achieve the correct delta-V pointing attitude. As a result, a higher accuracy was achieved on GOES-9 leading to more efficient delta-V maneuvers and a propellant savings. This paper summarizes the: Data observed on GOES-8 and the complications it caused in calibration; DIRA temperature/drift rate model; Application and results of the model on GOES-9 support.

  3. Refractive Secondary Solar Concentrator Demonstrated High-Temperature Operation

    NASA Technical Reports Server (NTRS)

    Wong, Wayne A.

    2002-01-01

    Space applications that utilize solar thermal energy--such as electric power conversion systems, thermal propulsion systems, and furnaces--require highly efficient solar concentration systems. The NASA Glenn Research Center is developing the refractive secondary concentrator, which uses refraction and total internal reflection to efficiently concentrate and direct solar energy. When used in combination with advanced lightweight primary concentrators, such as inflatable thin films, the refractive secondary concentrator enables very high system concentration ratios and very high temperatures. Last year, Glenn successfully demonstrated a secondary concentrator throughput efficiency of 87 percent, with a projected efficiency of 93 percent using an antireflective coating. Building on this achievement, Glenn recently successfully demonstrated high-temperature operation of the secondary concentrator when it was used to heat a rhenium receiver to 2330 F. The high-temperature demonstration of the concentrator was conducted in Glenn's 68-ft long Tank 6 thermal vacuum facility equipped with a solar simulator. The facility has a rigid panel primary concentrator that was used to concentrate the light from the solar simulator onto the refractive secondary concentrator. NASA Marshall Space Flight Center provided a rhenium cavity, part of a solar thermal propulsion engine, to serve as the high-temperature receiver. The prototype refractive secondary concentrator, measuring 3.5 in. in diameter and 11.2 in. long, is made of single-crystal sapphire. A water-cooled splash shield absorbs spillage light outside of the 3.5-in. concentrator aperture. Multilayer foil insulation composed of tungsten, molybdenum, and niobium is used to minimize heat loss from the hightemperature receiver. A liquid-cooled canister calorimeter is used to measure the heat loss through the multilayer foil insulation.

  4. New constant-temperature operating mode for graphite calorimeter at LNE-LNHB

    NASA Astrophysics Data System (ADS)

    Daures, J.; Ostrowsky, A.

    2005-09-01

    The realization of the unit of absorbed dose at LNE-LNHB is based on calorimetry with the present GR8 graphite calorimeter. For this reason the calorimetric technique must be maintained, developed and improved in the laboratory. The usual quasi-adiabatic operating mode at LNHB is based on the thermal feedback between the core (sensitive element) and the jacket (adjacent body). When a core-jacket temperature difference is detected, a commercially available analogue PID (Proportional, Integral, Derivative) controller sends to the jacket an amount of electrical power to reduce this difference. Nevertheless, the core and jacket temperatures increase with irradiations and electrical calibrations whereas the surrounding is maintained at a fixed temperature to shield against the room temperature variations. At radiotherapy dose rates, fewer than ten measurements, or electrical calibrations, per day can be performed. This paper describes the new constant-temperature operating mode which has been implemented recently to improve flexibility in use and, to some extent, accuracy. The core and the jacket temperatures are maintained at fixed temperatures. A steady state is achieved without irradiation. Then, under irradiation, the electrical power needed to maintain the assigned temperature in the core is reduced by the amount of heat generated by ionizing radiation. The difference between these electrical powers, without and with irradiation, gives the mean absorbed dose rate to the core. The quality of this electrical power substitution measurement is strongly dependent upon the quality of the core and jacket thermal control. The core temperature is maintained at the set value using a digital PID regulator developed at the laboratory with LabView software on PC for this purpose. This regulator is versatile and particularly well suited for calorimetry purposes. Measurements in a cobalt-60 beam have shown no significant difference (<0.09%) between the two operating modes, with

  5. High Temperature Electrolysis Pressurized Experiment Design, Operation, and Results

    SciTech Connect

    J.E. O'Brien; X. Zhang; G.K. Housley; K. DeWall; L. Moore-McAteer

    2012-09-01

    A new facility has been developed at the Idaho National Laboratory for pressurized testing of solid oxide electrolysis stacks. Pressurized operation is envisioned for large-scale hydrogen production plants, yielding higher overall efficiencies when the hydrogen product is to be delivered at elevated pressure for tank storage or pipelines. Pressurized operation also supports higher mass flow rates of the process gases with smaller components. The test stand can accommodate planar cells with dimensions up to 8.5 cm x 8.5 cm and stacks of up to 25 cells. It is also suitable for testing other cell and stack geometries including tubular cells. The pressure boundary for these tests is a water-cooled spool-piece pressure vessel designed for operation up to 5 MPa. Pressurized operation of a ten-cell internally manifolded solid oxide electrolysis stack has been successfully demonstrated up 1.5 MPa. The stack is internally manifolded and operates in cross-flow with an inverted-U flow pattern. Feed-throughs for gas inlets/outlets, power, and instrumentation are all located in the bottom flange. The entire spool piece, with the exception of the bottom flange, can be lifted to allow access to the internal furnace and test fixture. Lifting is accomplished with a motorized threaded drive mechanism attached to a rigid structural frame. Stack mechanical compression is accomplished using springs that are located inside of the pressure boundary, but outside of the hot zone. Initial stack heatup and performance characterization occurs at ambient pressure followed by lowering and sealing of the pressure vessel and subsequent pressurization. Pressure equalization between the anode and cathode sides of the cells and the stack surroundings is ensured by combining all of the process gases downstream of the stack. Steady pressure is maintained by means of a backpressure regulator and a digital pressure controller. A full description of the pressurized test apparatus is provided in this

  6. Operational forecasting of daily temperatures in the Valencia Region. Part I: maximum temperatures in summer.

    NASA Astrophysics Data System (ADS)

    Gómez, I.; Estrela, M.

    2009-09-01

    Extreme temperature events have a great impact on human society. Knowledge of summer maximum temperatures is very useful for both the general public and organisations whose workers have to operate in the open, e.g. railways, roadways, tourism, etc. Moreover, summer maximum daily temperatures are considered a parameter of interest and concern since persistent heat-waves can affect areas as diverse as public health, energy consumption, etc. Thus, an accurate forecasting of these temperatures could help to predict heat-wave conditions and permit the implementation of strategies aimed at minimizing the negative effects that high temperatures have on human health. The aim of this work is to evaluate the skill of the RAMS model in determining daily maximum temperatures during summer over the Valencia Region. For this, we have used the real-time configuration of this model currently running at the CEAM Foundation. To carry out the model verification process, we have analysed not only the global behaviour of the model for the whole Valencia Region, but also its behaviour for the individual stations distributed within this area. The study has been performed for the summer forecast period of 1 June - 30 September, 2007. The results obtained are encouraging and indicate a good agreement between the observed and simulated maximum temperatures. Moreover, the model captures quite well the temperatures in the extreme heat episodes. Acknowledgement. This work was supported by "GRACCIE" (CSD2007-00067, Programa Consolider-Ingenio 2010), by the Spanish Ministerio de Educación y Ciencia, contract number CGL2005-03386/CLI, and by the Regional Government of Valencia Conselleria de Sanitat, contract "Simulación de las olas de calor e invasiones de frío y su regionalización en la Comunidad Valenciana" ("Heat wave and cold invasion simulation and their regionalization at Valencia Region"). The CEAM Foundation is supported by the Generalitat Valenciana and BANCAIXA (Valencia, Spain).

  7. Operational forecasting of daily temperatures in the Valencia Region. Part II: minimum temperatures in winter.

    NASA Astrophysics Data System (ADS)

    Gómez, I.; Estrela, M.

    2009-09-01

    Extreme temperature events have a great impact on human society. Knowledge of minimum temperatures during winter is very useful for both the general public and organisations whose workers have to operate in the open, e.g. railways, roadways, tourism, etc. Moreover, winter minimum temperatures are considered a parameter of interest and concern since persistent cold-waves can affect areas as diverse as public health, energy consumption, etc. Thus, an accurate forecasting of these temperatures could help to predict cold-wave conditions and permit the implementation of strategies aimed at minimizing the negative effects that low temperatures have on human health. The aim of this work is to evaluate the skill of the RAMS model in determining daily minimum temperatures during winter over the Valencia Region. For this, we have used the real-time configuration of this model currently running at the CEAM Foundation. To carry out the model verification process, we have analysed not only the global behaviour of the model for the whole Valencia Region, but also its behaviour for the individual stations distributed within this area. The study has been performed for the winter forecast period from 1 December 2007 - 31 March 2008. The results obtained are encouraging and indicate a good agreement between the observed and simulated minimum temperatures. Moreover, the model captures quite well the temperatures in the extreme cold episodes. Acknowledgement. This work was supported by "GRACCIE" (CSD2007-00067, Programa Consolider-Ingenio 2010), by the Spanish Ministerio de Educación y Ciencia, contract number CGL2005-03386/CLI, and by the Regional Government of Valencia Conselleria de Sanitat, contract "Simulación de las olas de calor e invasiones de frío y su regionalización en la Comunidad Valenciana" ("Heat wave and cold invasion simulation and their regionalization at Valencia Region"). The CEAM Foundation is supported by the Generalitat Valenciana and BANCAIXA (Valencia

  8. Numerical study of high-power semiconductor lasers for operation at sub-zero temperatures

    NASA Astrophysics Data System (ADS)

    Hasler, K. H.; Frevert, C.; Crump, P.; Erbert, G.; Wenzel, H.

    2017-04-01

    We present results on the impact of the Al-content in the waveguide structure on the electro-optical characteristics of 9xx nm, GaAs-based high-power lasers operated at room (300 K) and at sub-zero (200 K) heat sink temperatures. Experimentally a strong improvement of conversion efficiency and output power has been found if the lasers are cooled down. Numerical simulations using a software tool which solves the thermo-dynamic based drift-diffusion equations are able to reproduce the experimental findings. The reasons for the improved performance at lower temperatures are the enhancement of the modal gain and the reduced accumulation of electrons in the p-confinement layers resulting in a reduction of the leakage current. The latter allows the realization of lasers with a reduced Al content having a smaller series resistance and thus further enlarged conversion efficiency at sub-zero temperatures.

  9. Welding stainless steels for structures operating at liquid helium temperature

    SciTech Connect

    Witherell, C.E.

    1980-04-18

    Superconducting magnets for fusion energy reactors require massive monolithic stainless steel weldments which must operate at extremely low temperatures under stresses approaching 100 ksi (700 MPa). A three-year study was conducted to determine the feasibility of producing heavy-section welds having usable levels of strength and toughness at 4.2/sup 0/K for fabrication of these structures in Type 304LN plate. Seven welding processes were evaluated. Test weldments in full-thickness plate were made under severe restraint to simulate that of actual structures. Type 316L filler metal was used for most welds. Welds deposited under some conditions and which solidify as primary austenite have exhibited intergranular embrittlement at 4.2/sup 0/K. This is believed to be associated with grain boundary metal carbides or carbonitrides precipitated during reheating of already deposited beads by subsequent passes. Weld deposits which solidify as primary delta ferrite appear immune. Through use of fully austenitic filler metals of low nitrogen content under controlled shielded metal arc welding conditions, and through use of filler metals solidifying as primary delta ferrite where only minimum residuals remain to room temperature, welds of Type 316L composition have been made with 4.2K yield strength matching that of Type 304LN plate and acceptable levels of soundness, ductility and toughness.

  10. Reduced group delay dispersion in quantum dot passively mode-locked lasers operating at elevated temperature

    NASA Astrophysics Data System (ADS)

    Mee, J. K.; Raghunathan, R.; Murrell, D.; Braga, A.; Li, Y.; Lester, L. F.

    2014-09-01

    A detailed study of the pulse characteristics emitted from a monolithic Quantum Dot (QD) passively Mode-Locked Laser (MLL) has been performed using a state-of-the-art Frequency Resolved Optical Gating (FROG) pulse measurement system. While traditionally the time-domain pulse characteristics of semiconductor MLLs have been studied using digital sampling oscilloscope or intensity autocorrelation techniques, the FROG measurements allow for simultaneous characterization of time and frequency, which has been shown to be necessary and sufficient for true determination of mode-locked stability. In this paper, FROG pulse measurements are presented on a two-section QD MLL operating over wide temperature excursions. The FROG measurement allows for extraction of the temporal and spectral intensity and phase profiles from which the Group Delay Dispersion (GDD) can be determined. The magnitude of the GDD is found to decrease from 16.1 to 3.5 ps/nm when the temperature is increased from 20 to 50 oC, mirroring the trend of pulse width reduction at elevated temperature, which has been shown to correlate strongly with reduced unsaturated absorption. The possibility to further optimize pulse generation via intra-cavity dispersion compensation in a novel three-section MLL design is also examined, and shows strong potential toward providing valuable insight into the optimal cavity designs and operating parameters for QD MLLs.

  11. Operating temperatures of open-rack installed photovoltaic inverters

    SciTech Connect

    Zhang, Z.; Wang, L.; Kurtz, S.; Wu, J.; Quan, P.; Sorensen, R.; Liu, S.; Bai, J. B.; Zhu, Z. W.

    2016-11-01

    This paper presents a model for evaluating the heat-sink and component temperatures of open-rack installed photovoltaic inverters. These temperatures can be used for predicting inverter reliability. Inverter heat-sink temperatures were measured for inverters connected to three grid-connected PV (photovoltaic) test systems in Golden, Colorado, US. A model is proposed for calculating the inverter heat-sink temperature based on the ambient temperature, the ratio of the consumed power to the rated power of the inverter, and the measured wind speed. To verify and study this model, more than one year of inverter DC/AC power, irradiance, wind speed, and heat sink temperature rise data were collected and analyzed. The model is shown to be accurate in predicting average inverter temperatures, but will require further refinement for prediction of transient temperatures.

  12. Graft copolymer-based lithium-ion battery for high-temperature operation

    NASA Astrophysics Data System (ADS)

    Hu, Qichao; Osswald, Sebastian; Daniel, Reece; Zhu, Yan; Wesel, Steven; Ortiz, Luis; Sadoway, Donald R.

    The use of conventional lithium-ion batteries in high temperature applications (>50 °C) is currently inhibited by the high reactivity and volatility of liquid electrolytes. Solvent-free, solid-state polymer electrolytes allow for safe and stable operation of lithium-ion batteries, even at elevated temperatures. Recent advances in polymer synthesis have led to the development of novel materials that exhibit solid-like mechanical behavior while providing the ionic conductivities approaching that of liquid electrolytes. Here we report the successful charge and discharge cycling of a graft copolymer electrolyte (GCE)-based lithium-ion battery at temperatures up to 120 °C. The GCE consists of poly(oxyethylene) methacrylate-g-poly(dimethyl siloxane) (POEM-g-PDMS) doped with lithium triflate. Using electrochemical impedance spectroscopy (EIS), we analyze the temperature stability and cycling behavior of GCE-based lithium-ion batteries comprised of a LiFePO 4 cathode, a metallic lithium anode, and an electrolyte consisting of a 20-μm-thick layer of lithium triflate-doped POEM-g-PDMS. Our results demonstrate the great potential of GCE-based Li-ion batteries for high-temperature applications.

  13. Faraday isolator stably operating in a wide temperature range

    NASA Astrophysics Data System (ADS)

    Mironov, E. A.; Voitovich, A. V.; Palashov, O. V.

    2016-03-01

    A method of stabilizing Faraday isolator characteristics at varying temperatures is proposed in this letter. The method is based on the use of a magnetic system with an inhomogeneous magnetic field and a magneto-optical element holder made of a material with a high value of thermal expansion coefficient. Changing the rotation angle of the polarization plane of radiation caused by the temperature variation of the magneto-optical element and the temperature dependence of its Verdet constant is compensated by its shifting in the magnetic field. The developed device demonstrates an isolation ratio of more than 40 dB at a temperature range of 25 °C. Estimates show the possibility of providing an isolation ratio of more than 45 dB in a temperature range of 60 °C.

  14. Loop Heat Pipe Operation Using Heat Source Temperature for Set Point Control

    NASA Technical Reports Server (NTRS)

    Ku, Jentung; Paiva, Kleber; Mantelli, Marcia

    2011-01-01

    Loop heat pipes (LHPs) have been used for thermal control of several NASA and commercial orbiting spacecraft. The LHP operating temperature is governed by the saturation temperature of its compensation chamber (CC). Most LHPs use the CC temperature for feedback control of its operating temperature. There exists a thermal resistance between the heat source to be cooled by the LHP and the LHP's CC. Even if the CC set point temperature is controlled precisely, the heat source temperature will still vary with its heat output. For most applications, controlling the heat source temperature is of most interest. A logical question to ask is: "Can the heat source temperature be used for feedback control of the LHP operation?" A test program has been implemented to answer the above question. Objective is to investigate the LHP performance using the CC temperature and the heat source temperature for feedback control

  15. Significant increase in wavelength, power, and temperature operating envelopes for semiconductor laser diode bars for solid-state lasers

    NASA Astrophysics Data System (ADS)

    Haden, J.; Plano, B.; Major, J.; Harnagel, G.; Endriz, J.

    Attention is given to the substantial increase in the performance envelope of AlGaAs base semiconductor laser diode array bars (QCW bars) that are available to designers of diode pumped solid-state lasers. Reliable QCW bar performance includes operation to 100 W/cm with greater than 10 exp 9 pulse life, 65 C operation, and 780 to 980 nm wavelength availability (60 W/cm). Consideration is also given to 247-W QCW operation. At Nd:YAG, YLF wavelengths (798-807 nm), significant improvements have been achieved in allowable operating temperature (to 65 C) and operating power (to 100 W). These improvements offer the opportunity for the design of high-efficiency solid-state laser systems that need to operate in relatively severe environments.

  16. Primary and Secondary Lithium Batteries Capable of Operating at Low Temperatures for Planetary Exploration

    NASA Technical Reports Server (NTRS)

    Smart, M. C.; Ratnakumar, B. V.; West, W. C.; Brandon, E. J.

    2011-01-01

    Objectives and Approach: (1) Develop advanced Li ]ion electrolytes that enable cell operation over a wide temperature range (i.e., -60 to +60 C). Improve the high temperature stability and lifetime characteristics of wide operating temperature electrolytes. (2) Define the performance limitations at low and high temperature extremes, as well as, life limiting processes. (3) Demonstrate the performance of advanced electrolytes in large capacity prototype cells.

  17. Extreme High and Low Temperature Operation of the Silicon-On-Insulator Type CHT-OPA Operational Amplifier

    NASA Technical Reports Server (NTRS)

    Patterson, Richard; Hammoud, Ahmad; Elbuluk, Malik

    2008-01-01

    A new operational amplifier chip based on silicon-on-insulator technology was evaluated for potential use in extreme temperature environments. The CHT-OPA device is a low power, precision operational amplifier with rail-to-rail output swing capability, and it is rated for operation between -55 C and +225 C. A unity gain inverting circuit was constructed utilizing the CHT-OPA chip and a few passive components. The circuit was evaluated in the temperature range from -190 C to +200 C in terms of signal gain and phase shift, and supply current. The investigations were carried out to determine suitability of this device for use in space exploration missions and aeronautic applications under wide temperature incursion. Re-restart capability at extreme temperatures, i.e. power switched on while the device was soaked at extreme temperatures, was also investigated. In addition, the effects of thermal cycling under a wide temperature range on the operation of this high performance amplifier were determined. The results from this work indicate that this silicon-on-insulator amplifier chip maintained very good operation between +200 C and -190 C. The limited thermal cycling had no effect on the performance of the amplifier, and it was able to re-start at both -190 C and +200 C. In addition, no physical degradation or packaging damage was introduced due to either extreme temperature exposure or thermal cycling. The good performance demonstrated by this silicon-on-insulator operational amplifier renders it a potential candidate for use in space exploration missions or other environments under extreme temperatures. Additional and more comprehensive characterization is, however, required to establish the reliability and suitability of such devices for long term use in extreme temperature applications.

  18. Numerical simulation of proton exchange membrane fuel cells at high operating temperature

    NASA Astrophysics Data System (ADS)

    Peng, Jie; Lee, Seung Jae

    A three-dimensional, single-phase, non-isothermal numerical model for proton exchange membrane (PEM) fuel cell at high operating temperature (T ≥ 393 K) was developed and implemented into a computational fluid dynamic (CFD) code. The model accounts for convective and diffusive transport and allows predicting the concentration of species. The heat generated from electrochemical reactions, entropic heat and ohmic heat arising from the electrolyte ionic resistance were considered. The heat transport model was coupled with the electrochemical and mass transport models. The product water was assumed to be vaporous and treated as ideal gas. Water transportation across the membrane was ignored because of its low water electro-osmosis drag force in the polymer polybenzimidazole (PBI) membrane. The results show that the thermal effects strongly affect the fuel cell performance. The current density increases with the increasing of operating temperature. In addition, numerical prediction reveals that the width and distribution of gas channel and current collector land area are key optimization parameters for the cell performance improvement.

  19. Low-temperature operation of a Buck DC/DC converter

    NASA Technical Reports Server (NTRS)

    Ray, Biswajit; Gerber, Scott S.; Patterson, Richard L.; Myers, Ira T.

    1995-01-01

    Low-temperature (77 K) operation of a 42/28 V, 175 W, 50 kHz PWM Buck DC/DC converter designed with commercially available components is reported. Overall, the converter losses decreased at 77 K compared to room temperature operation. A full-load efficiency of 97 percent was recorded at liquid-nitrogen temperature, compared to 95.8 percent at room temperature. Power MOSFET operation improved significantly where as the output rectifier operation deteriorated at low-temperature. The performance of the output filter inductor and capacitor did not change significantly at 77 K compared to room temperature performance. It is possible to achieve high-density and high efficiency power conversion at low-temperatures due to improved electronic, electrical and thermal properties of materials.

  20. High accuracy magnetic field sensors with wide operation temperature range

    NASA Astrophysics Data System (ADS)

    Vasil'evskii, I. S.; Vinichenko, A. N.; Rubakin, D. I.; Bolshakova, I. A.; Kargin, N. I.

    2016-10-01

    n+InAs(Si) epitaxial thin films heavily doped by silicon and Hall effect magnetic field sensors based on this structures have been fabricated and studied. We have demonstrated the successful formation of highly doped InAs thin films (∼100 nm) with the different intermediate layer arrangement and appropriate electron mobility values. Hall sensors performance parameters have been measured in wide temperature range. Obtained sensitivity varied from 1 to 40 Ω/T, while the best linearity and lower temperature coefficient have been found in the higher doped samples with lower electron mobility. We attribute this to the electron system degeneracy and decreased phonon contribution to electron mobility and resistance.

  1. Lithium Batteries and Supercapacitors Capable of Operating at Low Temperatures for Planetary Exploration

    NASA Technical Reports Server (NTRS)

    Smart, M. C.; Ratnakumar, B. V.; West, W. C.; Brandon, E. J.

    2012-01-01

    Demonstrated improved performance with wide operating temperature electrolytes containing ester co - solvents (i.e., methyl propionate and ethyl butyrate) in a number of prototype cells: center dot Successfully scaled up low temperature technology to 12 Ah size prismatic Li - ion cells (Quallion, LCC), and demonstrated good performance down to - 60 o C. center dot Demonstrated wide operating temperature range performance ( - 60 o to +60 o C) in A123 Systems LiFePO 4 - based lithium - ion cells containing methyl butyrate - based low temperature electrolytes. These systems were also demonstrated to have excellent cycle life performance at ambient temperatures, as well as the ability to be cycled up to high temperatures.

  2. Electrolytes for Wide Operating Temperature Lithium-Ion Cells

    NASA Technical Reports Server (NTRS)

    Smart, Marshall C. (Inventor); Bugga, Ratnakumar V. (Inventor)

    2016-01-01

    Provided herein are electrolytes for lithium-ion electrochemical cells, electrochemical cells employing the electrolytes, methods of making the electrochemical cells and methods of using the electrochemical cells over a wide temperature range. Included are electrolyte compositions comprising a lithium salt, a cyclic carbonate, a non-cyclic carbonate, and a linear ester and optionally comprising one or more additives.

  3. Low threshold interband cascade lasers operating above room temperature

    NASA Technical Reports Server (NTRS)

    Hill, C. J.; Yang, B.; Yang, R. Q.

    2003-01-01

    Mid-IR type-II interband cascade lasers were demonstrated in pulsed mode at temperatures up to 325 K and in continuous mode up to 200 K. At 80 K, the threshold current density was 8.9 A/cm2 and a cw outpout power of 140 mW/facet was obtained.

  4. Silicon solar cell monitors high temperature furnace operation

    NASA Technical Reports Server (NTRS)

    Zellner, G. J.

    1968-01-01

    Silicon solar cell, attached to each viewpoint, monitors that incandescent emission from the hot interior of a furnace without interfering with the test assembly or optical pyrometry during the test. This technique can provide continuous indication of hot spots or provide warning of excessive temperatures in cooler regions.

  5. Operational experience with room temperature continuous wave accelerator structures

    NASA Astrophysics Data System (ADS)

    Alimov, A. S.; Ishkhanov, B. S.; Piskarev, I. M.; Shvedunov, V. I.; Tiunov, A. V.

    1993-05-01

    The paper reports the results of the computer simulation of parameters of the on-axis coupled accelerator structure for the continuous wave racetrack microtron. The operational experience with the accelerating sections on the basis of the on-axis coupled structure is described.

  6. Electromagnetic power absorption and temperature changes due to brain machine interface operation.

    PubMed

    Ibrahim, Tamer S; Abraham, Doney; Rennaker, Robert L

    2007-05-01

    To fully understand neural function, chronic neural recordings must be made simultaneously from 10s or 100s of neurons. To accomplish this goal, several groups are developing brain machine interfaces. For these devices to be viable for chronic human use, it is likely that they will need to be operated and powered externally via a radiofrequency (RF) source. However, RF exposure can result in tissue heating and is regulated by the FDA/FCC. This paper provides an initial estimate of the amount of tissue heating and specific absorption rate (SAR) associated with the operation of a brain-machine interface (BMI). The operation of a brain machine interface was evaluated in an 18-tissue anatomically detailed human head mesh using simulations of electromagnetics and bio-heat phenomena. The simulations were conducted with a single chip, as well as with eight chips, placed on the surface of the human brain and each powered at four frequencies (13.6 MHz, 1.0 GHz, 2.4 GHz, and 5.8 GHz). The simulated chips consist of a wire antenna on a silicon chip covered by a Teflon dura patch. SAR values were calculated using the finite-difference time-domain method and used to predict peak temperature changes caused by electromagnetic absorption in the head using two-dimensional bio-heat equation. Results due to SAR alone show increased heating at higher frequencies, with a peak temperature change at 5.8 GHz of approximately 0.018 degrees C in the single-chip configuration and 0.06 degrees C in the eight-chip configuration with 10 mW of power absorption (in the human head) per chip. In addition, temperature elevations due to power dissipation in the chip(s) were studied. Results show that for the neural tissue, maximum temperature rises of 3.34 degrees C in the single-chip configuration and 7.72 degrees C in the eight-chip configuration were observed for 10 mW dissipation in each chip. Finally, the maximum power dissipation allowable in each chip before a 1.0 degrees C temperature

  7. Impacts of operation of CVP regulating reservoirs on water temperature

    SciTech Connect

    Vail, L.W.

    1996-06-01

    The Western Area Power Administration (Western) markets and transmits electric power throughout 15 western states. Western's Sierra Nevada Customer Service Region (Sierra Nevada Region) markets approximately 1,480 megawatts (MW) of firm power (and 100 MW of seasonal peaking capacity) from the Central Valley Project (CVP) and other sources and markets available nonfirm power from the Washoe Project. Western's mission is to sell and deliver electricity generated from CVP powerplants. The hydroelectric facilities of the CVP are operated by the Bureau of Reclamation (Reclamation). Reclamation manages and releases water in accordance with the various acts authorizing specific projects and with enabling legislation. Western's capacity and energy sales must be in conformance with the laws that govern its sale of electrical power. Further, Western's hydropower operations at each facility must comply with minimum and maximum flows and other constraints set by Reclamation, the U.S. Fish and Wildlife Service, or other agencies, acting in accord with law or policy.

  8. Electrolytes for Use in High Energy Lithium-Ion Batteries with Wide Operating Temperature Range

    NASA Technical Reports Server (NTRS)

    Smart, Marshall C.; Ratnakumar, B. V.; West, W. C.; Whitcanack, L. D.; Huang, C.; Soler, J.; Krause, F. C.

    2011-01-01

    Objectives of this work are: (1) Develop advanced Li -ion electrolytes that enable cell operation over a wide temperature range (i.e., -30 to +60C). (2) Improve the high temperature stability and lifetime characteristics of wide operating temperature electrolytes. (3) Improve the high voltage stability of these candidate electrolytes systems to enable operation up to 5V with high specific energy cathode materials. (4) Define the performance limitations at low and high temperature extremes, as well as, life limiting processes. (5) Demonstrate the performance of advanced electrolytes in large capacity prototype cells.

  9. Loop Heat Pipe Operation Using Heat Source Temperature for Set Point Control

    NASA Technical Reports Server (NTRS)

    Ku, Jentung; Paiva, Kleber; Mantelli, Marcia

    2011-01-01

    The LHP operating temperature is governed by the saturation temperature of its reservoir. Controlling the reservoir saturation temperature is commonly accomplished by cold biasing the reservoir and using electrical heaters to provide the required control power. Using this method, the loop operating temperature can be controlled within +/- 0.5K. However, because of the thermal resistance that exists between the heat source and the LHP evaporator, the heat source temperature will vary with its heat output even if LHP operating temperature is kept constant. Since maintaining a constant heat source temperature is of most interest, a question often raised is whether the heat source temperature can be used for LHP set point temperature control. A test program with a miniature LHP has been carried out to investigate the effects on the LHP operation when the control temperature sensor is placed on the heat source instead of the reservoir. In these tests, the LHP reservoir is cold-biased and is heated by a control heater. Tests results show that it is feasible to use the heat source temperature for feedback control of the LHP operation. Using this method, the heat source temperature can be maintained within a tight range for moderate and high powers. At low powers, however, temperature oscillations may occur due to interactions among the reservoir control heater power, the heat source mass, and the heat output from the heat source. In addition, the heat source temperature could temporarily deviate from its set point during fast thermal transients. The implication is that more sophisticated feedback control algorithms need to be implemented for LHP transient operation when the heat source temperature is used for feedback control.

  10. Operation of silicon single photon avalanche diodes at cryogenic temperature.

    PubMed

    Rech, Ivan; Labanca, Ivan; Armellini, Giacomo; Gulinatti, Angelo; Ghioni, Massimo; Cova, Sergio

    2007-06-01

    This article reports a complete characterization of single photon avalanche diodes (SPADs) at temperatures down to 120 K. We show that deep cooling of the device by means of a compact liquid-nitrogen Dewar brings several advantages, such as extremely low dark counting rates (down to 1 counts/s), better time resolution, and higher quantum efficiency in the visible range. By using a special current pick-off circuit, we achieved a time resolution of 20 ps full width at half maximum at 120 K for a 50 mum diameter SPAD. Afterpulsing effects are avoided by using a sufficiently long hold-off time (microseconds).

  11. Scheduling field operations as a function of temperature, soil moisture, and available resources

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Scheduling field operations in SWAT can be done by specifying fixed dates or by using the heat unit index, which considers temperature constraints. However, soil moisture and labor requirements can also limit the ability of farm operators to perform field operations at the optimal time. The SWAT2012...

  12. High-Operating-Temperature Barrier Infrared Detector with Tailorable Cutoff Wavelength

    NASA Technical Reports Server (NTRS)

    Ting, David Z.; Hill, Cory, J.; Soibel, Alexander; Bandara, Sumith V.; Gunapala, Sarath D.

    2011-01-01

    A mid-wavelength infrared (MWIR) barrier photodetector is capable of operating at higher temperature than the prevailing MWIR detectors based on InSb. The standard high-operating-temperature barrier infrared detector (HOT-BIRD) is made with an InAsSb infrared absorber that is lattice-matched to a GaSb substrate, and has a cutoff wavelength of approximately 4 microns. To increase the versatility and utility of the HOT-BIRD, it is implemented with IR absorber materials with customizable cutoff wavelengths. The HOT-BIRD can be built with the quaternary alloy GaInAsSb as the absorber, GaAlSbAs as the barrier, on a lattice-matching GaSb substrate. The cutoff wavelength of the GaInAsSb can be tailored by adjusting the alloy composition. To build a HOT-BIRD requires a matching pair of absorber and barrier materials with the following properties: (1) their valence band edges must be approximately the same to allow unimpeded hole flow, while their conduction band edges should have a large difference to form an electron barrier; and (2) the absorber and the barrier must be respectively lattice-matched and closely lattice-matched to the substrate to ensure high material quality and low defect density. To make a HOT-BIRD with cutoff wavelength shorter than 4 microns, a GaInAsSb quaternary alloy was used as the absorber, and a matching GaAlSbAs quaternary alloy as the barrier. By changing the alloy composition, the band gap of the quaternary alloy absorber can be continuously adjusted with cutoff wavelength ranging from 4 microns down to the short wavelength infrared (SWIR). By carefully choosing the alloy composition of the barrier, a HOT-BIRD structure can be formed. With this method, a HOT-BIRD can be made with continuously tailorable cutoff wavelengths from 4 microns down to the SWIR. The HOT-BIRD detector technology is suitable for making very-large-format MWIR/SWIR focal plane arrays that can be operated by passive cooling from low Earth orbit. High-operating temperature

  13. Liquid temperature determination in a seasonal heat storage at joint operation with a solar collector and thermal energy consumer

    SciTech Connect

    Sivoraksha, V.E.; Zolotko, K.E.; Markov, V.L.; Petrov, B.E.; Lyagushyn, S.F.

    1998-07-01

    Usual solar thermal systems include a solar collector providing solar power conversion into the thermal form and a heat storage accumulating thermal energy, the great capacity of storage systems allows heating and hot water supply during the cold season. The joint operation of the solar collector and a seasonal heat storage has a cyclic mode day by day. The following operation scheme is analyzed in the paper: in night liquid (water) does not circulate; after sunrise the solar collector is warmed up and after its temperature reaching the temperature of water in the thermal energy storage TTS circulation is switched on and thermal power is transferred to the heat storage; after midday water temperature in the solar collector decreases and circulation stops when it becomes equal to the heat storage temperature. TTS increase results in the reduction of the duration of the joint operation of the solar collector and the energy storage and in the decrease of the heat power input. A functional connection between the daily input of power from the solar collector and an average temperature in the heat storage is of importance for technological calculations. The moments of the beginning and end of circulation and daily heat input from the solar collector are determined under the assumption of the sinusoidal law of solar radiation coming in the day-time. Then the heat balance equation is solved for the whole power system with taking into account power consumption and heat losses. The polynomial approximation for the dependence of heat input upon heat carrier temperature permits obtaining an analytical solution for the seasonal behavior of the liquid temperature in the thermal energy storage. The obtained dependence of TTS upon time allows calculation of this parameter with admissible accuracy at the stage of the project development proceeding from the performance of the solar collector and heat storage and from the averaged meteorological data.

  14. Miniature cryocooler developments for high operating temperatures at Thales Cryogenics

    NASA Astrophysics Data System (ADS)

    Arts, R.; Martin, J.-Y.; Willems, D.; Seguineau, C.; Van Acker, S.; Mullié, J. C.; Göbel, A.; Tops, M.; Le Bordays, J.; Etchanchu, T.; Benschop, A. A. J.

    2015-05-01

    In recent years there has been a drive towards miniaturized cooled IDCA solutions for low-power, low-mass, low-size products (SWaP). To support this drive, coolers are developed optimized for high-temperature, low heat load dewar-detector assemblies. In this paper, Thales Cryogenics development activities supporting SWaP are presented. Design choices are discussed and compared to various key requirements. Trade-off analysis results are presented on drive voltage, cold finger definition (length, material, diameter and sealing concept), and other interface considerations, including cold finger definition. In parallel with linear and rotary cooler options, designs for small-size high-efficiency drive electronics based on state-of-the-art architectures are presented.

  15. Small CO2 Sensors Operate at Lower Temperature

    NASA Technical Reports Server (NTRS)

    Hunter, Gary W.; Xu, Jennifer C.

    2009-01-01

    Solid-electrolyte-based amperometric sensors for measuring concentrations of CO2 in air are being developed for use in detection of fires, environmental monitoring, and other applications where liquid-based electrochemical cells are problematic. These sensors are small (sizes of the order of a millimeter), are robust, are amenable to batch fabrication at relatively low cost, and exhibit short response times (seconds) and wide detection ranges. A sensor of this type at a previous stage of development included a solid electrolyte of Na3Zr2Si2PO12 deposited mainly between interdigitated Pt electrodes on an alumina substrate, all overcoated with an auxiliary solid electrolyte of (Na2CO3:BaCO3 in a molar ratio of 1:1.7). It was necessary to heat this device to a temperature as high as 600 C to obtain the desired sensitivity and rapid response. Heating sensors increases the power consumption of the sensor system and complicates the use of the sensor in some applications. Thus, decreasing a sensor s power consumption while maintaining its performance is a technical goal of ongoing development.

  16. DYNAMIC RESPONSE OF STREAM TEMPERATURES TO BOUNDARY AND INFLOW PERTURBATION DUE TO RESERVOIR OPERATIONS

    SciTech Connect

    Khangaonkar, Tarang P.; Yang, Zhaoqing

    2008-05-01

    Dams and reservoir operations modify natural stream behaviour and affect the downstream characteristics such as mean temperatures and diurnal temperature amplitudes. Managing phase effects due to reservoir operation and the associated amplification of daily maximum temperatures in the downstream reaches remains a challenge. An analytical approach derived from a one-dimensional heat advection and dispersion equation with surface heating in the form of equilibrium temperature was developed to examine the potential for restoration of natural stream temperatures. The analytical model was validated with observed temperature data collected in the Clackamas River, Oregon, and was used to highlight key downstream temperature behaviour characteristics. Mean stream temperatures below the dam are relatively stable and upon deviating from natural stream mean temperatures, return asymptotically to their natural state. In contrast, the amplitudes of daily temperature variation are highly sensitive to the phase differences induced by the dam and could nearly double in natural amplitude within the first 24 h. The analysis showed that restoring average stream temperatures to natural levels through structural and operational modifications at the dam may not be sufficient as phase-induced temperatures maximums would continue to persist

  17. High-power QCW arrays for operation over wide temperature extremes

    NASA Astrophysics Data System (ADS)

    Feeler, Ryan; Junghans, Jeremy; Stephens, Ed

    2009-02-01

    A family of laser diode arrays has been developed for QCW operation in adverse environmental conditions. The arrays contain expansion-matched heatsinks, hard solder, and are built using a process that minimizes the packaging-induced strain on the laser diode bars. The arrays are rated for operation at 200 Watts/bar under normal operating conditions. This work contains test results for these arrays when run under a variety of harsh operating conditions. The conditions were chosen to mimic those required by many military and aerospace laser programs. Life test results are presented over a range of operating temperatures common to military specifications (-40 °C to + 70 °C) at a power level of approximately 215 Watts/bar. The arrays experienced no measurable degradation over the course of the life test. Operation at the temperature extremes did not introduce any additional detectable failure mechanisms. Also presented are results of characterization and reliability tests conducted at cryogenic temperatures. Diode arrays have been subjected to repeated cycles in rapid succession between room temperature and 77 K with temperature ramp rates up to 100 K/minute. Pre- and post- thermal cycle P-I-V data are compared. The results demonstrate the suitability of these arrays for operation at cryogenic temperatures.

  18. Effect of External Pressure Drop on Loop Heat Pipe Operating Temperature

    NASA Technical Reports Server (NTRS)

    Jentung, Ku; Ottenstein, Laura; Rogers, Paul; Cheung, Kwok; Obenschain, Arthur F. (Technical Monitor)

    2002-01-01

    This paper discusses the effect of the pressure drop on the operating temperature in a loop heat pipe (LHP). Because the evaporator and the compensation chamber (CC) both contain two-phase fluid, a thermodynamic constraint exists between the temperature difference and the pressure drop for these two components. As the pressure drop increases, so will the temperature difference. The temperature difference in turn causes an increase of the heat leak from the evaporator to the CC, resulting in a higher CC temperature. Furthermore, the heat leak strongly depends on the vapor void fraction inside the evaporator core. Tests were conducted by installing a valve on the vapor line so as to vary the pressure drop, and by charging the LHP with various amounts of fluid. Test results verify that the LHP operating temperature increases with an increasing differential pressure, and the temperature increase is a strong function of the fluid inventory in the loop.

  19. Promotion of Flowering by Apple Latent Spherical Virus Vector and Virus Elimination at High Temperature Allow Accelerated Breeding of Apple and Pear

    PubMed Central

    Yamagishi, Norioko; Li, Chunjiang; Yoshikawa, Nobuyuki

    2016-01-01

    Plant viral vectors are superior tools for genetic manipulation, allowing rapid induction or suppression of expression of a target gene in plants. This is a particularly effective technology for use in breeding fruit trees, which are difficult to manipulate using recombinant DNA technologies. We reported previously that if apple seed embryos (cotyledons) are infected with an Apple latent spherical virus (ALSV) vector (ALSV-AtFT/MdTFL1) concurrently expressing the Arabidopsis thaliana florigen (AtFT) gene and suppressing the expression of the apple MdTFL1-1 gene, the period prior to initial flowering (generally lasts 5–12 years) will be reduced to about 2 months. In this study, we examined whether or not ALSV vector technology can be used to promote flowering in pear, which undergoes a very long juvenile period (germination to flowering) similar to that of apple. The MdTFL1 sequence in ALSV-AtFT/MdTFL1 was replaced with a portion of the pear PcTFL1-1 gene. The resulting virus (ALSV-AtFT/PcTFL1) and ALSV-AtFT/MdTFL1 were used individually for inoculation to pear cotyledons immediately after germination in two inoculation groups. Those inoculated with ALSV-AtFT/MdTFL1 and ALSV-AtFT/PcTFL1 then initiated flower bud formation starting one to 3 months after inoculation, and subsequently exhibited continuous flowering and fruition by pollination. Conversely, Japanese pear exhibited extremely low systemic infection rates when inoculated with ALSV-AtFT/MdTFL1, and failed to exhibit any induction of flowering. We also developed a simple method for eliminating ALSV vectors from infected plants. An evaluation of the method for eliminating the ALSV vectors from infected apple and pear seedlings revealed that a 4-week high-temperature (37°C) incubation of ALSV-infected apples and pears disabled the movement of ALSV to new growing tissues. This demonstrates that only high-temperature treatment can easily eliminate ALSV from infected fruit trees. A method combining the

  20. Conductor and associated hardware impacts during high temperature operations: Issues and problems. Final report

    SciTech Connect

    Shan, L.; Douglass, D.

    1997-12-01

    This report summarizes the results of a sensitivity study of high temperature conductor sag. Relevant calculations were performed using suitable sag-tension computer programs to quantify the sensitivity and range of possible errors related to the common conductor parameters which affect calculated high temperature sag (e.g., conductor creep, loading history, effect of ruling span design, interaction of steel and aluminum, differences in installation and manufacturing temperatures, radial temperatures, etc.). Additionally, it addresses the factors that cause errors in the calculation of high temperature sag for overhead transmission lines and suggests future development work in the area of high temperature operation. This report also discusses issues related to the life of conductors and hardware operated at elevated temperatures. Based on the results of this preliminary study, recommendations are provided for improving the ability to predict the performance of conductors and hardware operated at high temperature. This information is useful to utility engineers when designing new power lines or evaluating existing lines for high temperature operation.

  1. HTCAP-1: a program for calcuating operating temperatures in HFIR target irradiation experiments

    SciTech Connect

    Kania, M.J.; Howard A.M.

    1980-06-01

    The thermal modeling code, HTCAP-1, calculates in-reactor operating temperatures of fueled specimens contained in the High Flux Isotope Reactor (HFIR) target irradiation experiments (HT-series). Temperature calculations are made for loose particle and bonded fuel rod specimens. Maximum particle surface temperatures are calculated for the loose particles and centerline and surface temperatures for the fuel rods. Three computational models are employed to determine fission heat generation rates, capsule heat transfer analysis, and specimen temperatures. This report is also intended to be a users' manual, and the application of HTCAP-1 to the HT-34 irradiation capsule is presented.

  2. Low Frequency High Amplitude Temperature Oscillations in Loop Heat Pipe Operation

    NASA Technical Reports Server (NTRS)

    Ku, Jentung; Rodriguez, Jose

    2003-01-01

    This paper presents viewgraphs on the low frequency high amplitude temperature oscillations observed in loop heat pipe operations. The topics include: 1) Proposed Theory; 2) Test Loop and Test Results; and 3) Effects of Various Parameters. The author also presents a short summary on the conditiions that must be met in order to sustain a low frequency high amplitude temperature oscillation.

  3. Temperature Compensated Sapphire Resonator for Ultrastable Oscillator Operating at Temperatures Near 77 Deg Kelvin

    NASA Technical Reports Server (NTRS)

    Dick, G. John (Inventor); Santiago, David G. (Inventor)

    1999-01-01

    A sapphire resonator for an ultrastable oscillator capable of substantial performance improvements over the best available crystal quartz oscillators in a compact cryogenic package is based on a compensation mechanism enabled by the difference between copper and sapphire thermal expansion coefficients for so tuning the resonator as to cancel the temperature variation of the sapphire's dielectric constant. The sapphire resonator consists of a sapphire ring separated into two parts with webs on the outer end of each to form two re-entrant parts which are separated by a copper post. The re-entrant parts are bonded to the post by indium solder for good thermal conductivity between parts of that subassembly which is supported on the base plate of a closed copper cylinder (rf shielding casing) by a thin stainless steel cylinder. A unit for temperature control is placed in the stainless steel cylinder and is connected to the subassembly of re-entrant parts and copper post by a layer of indium for good thermal conduction. In normal use, the rf shielding casing is placed in a vacuum tank which is in turn placed in a thermos flask of liquid nitrogen. The temperature regulator is controlled from outside the thermos flask to a temperature in a range of about 40K to 150K, such as 87K for the WGH-811, mode of resonance in response to microwave energy inserted into the rf shielding casing through a port from an outside source.

  4. On the operation of silicon photomultipliers at temperatures of 1-4 kelvin

    NASA Astrophysics Data System (ADS)

    Achenbach, P.; Biroth, M.; Downie, E.; Thomas, A.

    2016-07-01

    SiPM operation at cryogenic temperatures fails for many common devices. A particular type from Zecotek with deep channels in the silicon substrate instead of quenching resistors was tested at liquid helium temperature. Two similar types were thoroughly characterized from room temperature down to liquid nitrogen temperature by illuminating them with low light levels. At cryogenic temperatures the SiPMs show an unchanged rise-time and a fast recovery time, practically no after-pulses, and exhibit no increased cross-talk probability. Charge collection spectra were measured to extract the pixel gain and its variation, both comparable to room temperature at the same over-voltage. The quenching resistance was decreased at cryogenic temperature. It was found possible to use the characterized devices at temperatures of 1-4 K for the read-out of a target at the Mainz Microtron in Germany.

  5. Hybrid sulfur cycle operation for high-temperature gas-cooled reactors

    DOEpatents

    Gorensek, Maximilian B

    2015-02-17

    A hybrid sulfur (HyS) cycle process for the production of hydrogen is provided. The process uses a proton exchange membrane (PEM) SO.sub.2-depolarized electrolyzer (SDE) for the low-temperature, electrochemical reaction step and a bayonet reactor for the high-temperature decomposition step The process can be operated at lower temperature and pressure ranges while still providing an overall energy efficient cycle process.

  6. Designing Nanoscale Precipitates in Novel Cobalt-based Superalloys to Improve Creep Resistance and Operating Temperature

    SciTech Connect

    Dunand, David C.; Seidman, David N.; Wolverton, Christopher; Saal, James E.; Bocchini, Peter J.; Sauza, Daniel J.

    2014-10-01

    High-temperature structural alloys for aerospace and energy applications have long been dominated by Ni-base superalloys, whose strength and creep resistance can be attributed to microstructures consisting of a large volume fraction of ordered (L12) γ'-precipitates embedded in a disordered’(f.c.c.) γ-matrix. These alloys exhibit excellent mechanical behavior and thermal stability, but after decades of incremental improvement are nearing the theoretical limit of their operating temperatures. Conventional Co-base superalloys are solid-solution or carbide strengthened; although they see industrial use, these alloys are restricted to lower-stress applications because the absence of an ordered intermetallic phase places an upper limit on their mechanical performance. In 2006, a γ+γ' microstructure with ordered precipitates analogous to (L12) Ni3Al was first identified in the Co-Al-W ternary system, allowing, for the first time, the development of Co-base alloys with the potential to meet or even exceed the elevated-temperature performance of their Ni-base counterparts. The potential design space for these alloys is complex: the most advanced Ni-base superalloys may contain as many as 8-10 minor alloying additions, each with a specified purpose such as raising the γ' solvus temperature or improving creep strength. Our work has focused on assessing the effects of alloying additions on microstructure and mechanical behavior of γ'-strengthened Co-base alloys in an effort to lay the foundations for understanding this emerging alloy system. Investigation of the size, morphology, and composition of γ' and other relevant phases is investigated utilizing scanning electron microscopy (SEM) and 3-D picosecond ultraviolet local electrode atom probe tomography (APT). Microhardness, compressive yield stress at ambient and elevated temperatures, and compressive high-temperature creep measurements are employed to extract mechanical behavior

  7. High Temperature Electrolysis 4 kW Experiment Design, Operation, and Results

    SciTech Connect

    J.E. O'Brien; X. Zhang; K. DeWall; L. Moore-McAteer; G. Tao

    2012-09-01

    This report provides results of long-term stack testing completed in the new high-temperature steam electrolysis multi-kW test facility recently developed at INL. The report includes detailed descriptions of the piping layout, steam generation and delivery system, test fixture, heat recuperation system, hot zone, instrumentation, and operating conditions. This facility has provided a demonstration of high-temperature steam electrolysis operation at the 4 kW scale with advanced cell and stack technology. This successful large-scale demonstration of high-temperature steam electrolysis will help to advance the technology toward near-term commercialization.

  8. The Effective Lifetime of ACSR Full Tension Splice Connector Operated at Higher Temperature

    SciTech Connect

    Wang, Jy-An John; Lara-Curzio, Edgar; King Jr, Thomas J; Graziano, Joe; Chan, John; Goodwin, Tip

    2009-01-01

    This paper is to address the issues related to integrity of ACSR full tension splice connectors operated at high temperatures. A protocol of integrating analytical and experimental approaches to evaluate the integrity of a full tension single-stage splice connector (SSC) assembly during service at high operating temperature was developed. Based on the developed protocol the effective lifetime evaluation was demonstrated with ACSR Drake conductor SSC systems. The investigation indicates that thermal cycling temperature and frequency, conductor cable tension loading, and the compressive residual stress field within a SSC system have significant impact on the SSC integrity and the associated effective lifetime.

  9. Operation of SOI P-Channel Field Effect Transistors, CHT-PMOS30, under Extreme Temperatures

    NASA Technical Reports Server (NTRS)

    Patterson, Richard; Hammoud, Ahmad

    2009-01-01

    Electronic systems are required to operate under extreme temperatures in NASA planetary exploration and deep space missions. Electronics on-board spacecraft must also tolerate thermal cycling between extreme temperatures. Thermal management means are usually included in today s spacecraft systems to provide adequate temperature for proper operation of the electronics. These measures, which may include heating elements, heat pipes, radiators, etc., however add to the complexity in the design of the system, increases its cost and weight, and affects its performance and reliability. Electronic parts and circuits capable of withstanding and operating under extreme temperatures would reflect in improvement in system s efficiency, reducing cost, and improving overall reliability. Semiconductor chips based on silicon-on-insulator (SOI) technology are designed mainly for high temperature applications and find extensive use in terrestrial well-logging fields. Their inherent design offers advantages over silicon devices in terms of reduced leakage currents, less power consumption, faster switching speeds, and good radiation tolerance. Little is known, however, about their performance at cryogenic temperatures and under wide thermal swings. Experimental investigation on the operation of SOI, N-channel field effect transistors under wide temperature range was reported earlier [1]. This work examines the performance of P-channel devices of these SOI transistors. The electronic part investigated in this work comprised of a Cissoid s CHT-PMOS30, high temperature P-channel MOSFET (metal-oxide semiconductor field-effect transistor) device [2]. This high voltage, medium-power transistor is designed for geothermal well logging applications, aerospace and avionics, and automotive industry, and is specified for operation in the temperature range of -55 C to +225 C. Table I shows some specifications of this transistor [2]. The CHT-PMOS30 device was characterized at various temperatures

  10. High Operating Temperature Midwave Quantum Dot Barrier Infrared Detector (QD-BIRD)

    NASA Technical Reports Server (NTRS)

    Ting, David Z.; Soibel, Alexander; Hill, Cory J.; Keo, Sam A.; Mumolo, Jason M.; Gunapala, Sarath D.

    2012-01-01

    The nBn or XBn barrier infrared detector has the advantage of reduced dark current resulting from suppressed Shockley-Read-Hall (SRH) recombination and surface leakage. High performance detectors and focal plane arrays (FPAs) based on InAsSb absorber lattice matched to GaSb substrate, with a matching AlAsSb unipolar electron barrier, have been demonstrated. The band gap of lattice-matched InAsSb yields a detector cutoff wavelength of approximately 4.2 ??m when operating at 150K. We report results on extending the cutoff wavelength of midwave barrier infrared detectors by incorporating self-assembled InSb quantum dots into the active area of the detector. Using this approach, we were able to extend the detector cutoff wavelength to 6 ?m, allowing the coverage of the full midwave infrared (MWIR) transmission window. The quantum dot barrier infrared detector (QD-BIRD) shows infrared response at temperatures up to 225 K.

  11. Comparison of rechargeable versus battery-operated insulin pumps: temperature fluctuations.

    PubMed

    Vereshchetin, Paul; McCann, Thomas W; Ojha, Navdeep; Venugopalan, Ramakrishna; Levy, Brian L

    2016-01-01

    The role of continuous subcutaneous insulin infusion (insulin pumps) has become increasingly important in diabetes management, and many different types of these systems are currently available. This exploratory study focused on the reported heating issues that lithium-ion battery-powered pumps may have during charging compared with battery-operated pumps. It was found that pump temperature increased by 6.4°C during a long charging cycle of a lithiumion battery-operated pump under ambient temperatures. In an environmental-chamber kept at 35°C, the pump temperature increased by 4.4°C, which indicates that the pump temperature was above that of the recommended safety limit for insulin storage of 37°C. When designing new pumps, and when using currently available rechargeable pumps in warmer climates, the implications of these temperature increases should be taken into consideration. Future studies should also further examine insulin quality after charging.

  12. Comparison of rechargeable versus battery-operated insulin pumps: temperature fluctuations

    PubMed Central

    Vereshchetin, Paul; McCann, Thomas W; Ojha, Navdeep; Venugopalan, Ramakrishna; Levy, Brian L

    2016-01-01

    The role of continuous subcutaneous insulin infusion (insulin pumps) has become increasingly important in diabetes management, and many different types of these systems are currently available. This exploratory study focused on the reported heating issues that lithium-ion battery-powered pumps may have during charging compared with battery-operated pumps. It was found that pump temperature increased by 6.4°C during a long charging cycle of a lithiumion battery-operated pump under ambient temperatures. In an environmental-chamber kept at 35°C, the pump temperature increased by 4.4°C, which indicates that the pump temperature was above that of the recommended safety limit for insulin storage of 37°C. When designing new pumps, and when using currently available rechargeable pumps in warmer climates, the implications of these temperature increases should be taken into consideration. Future studies should also further examine insulin quality after charging. PMID:27789976

  13. Operative environmental temperatures and basking behavior of the turtle Pseudemys scripta

    SciTech Connect

    Crawford, K.M.; Spotila, J.R.; Standora, E.A.

    1983-01-01

    Operative environmental temperatures (T/sub e/, an index of the thermal environment) were measured for basking Pseudemys scripta in South Carolina. Operative environmental temperatures were good predictors of the basking behavior of P. scripta. Turtles in this study generally did not bask unless T/sub e/ was 28/sup 0/C (preferred body temperature) or higher. This demonstrated that basking was not a random behavior in respect to T/sub e/, and implicated thermoregulation as a major factor eliciting basking behavior. Operative environmental temperature was positively related to short-wave and total solar radiation as well as to air and substrate temperature. Substrate temperature was the best single predictor of T/sub e/. A multiple regression equation (T/sub e/ = 0.005R + 0.103T/sub a/ - 1.16 log V + 0.932T/sub s/ - 2.54, r/sup 2/ = .90, where R = total radiation in watts per square metre, T/sub a/ = air temperature in degrees Celsius, V = wind speed in metres per second, and T/sub s/ = substrate temperature in degrees Celsius) defines the relationship of T/sub e/ to microclimate variables. Movement of the sun through the day results in spatial variation in T/sub e/'s available to turtles and influences their location and basking behavior.

  14. Electrolytes for Use in High Energy Lithium-ion Batteries with Wide Operating Temperature Range

    NASA Technical Reports Server (NTRS)

    Smart, Marshall C.; Ratnakumar, B. V.; West, W. C.; Whitcanack, L. D.; Huang, C.; Soler, J.; Krause, F. C.

    2012-01-01

    Met programmatic milestones for program. Demonstrated improved performance with wide operating temperature electrolytes containing ester co-solvents (i.e., methyl butyrate) containing electrolyte additives in A123 prototype cells: Previously demonstrated excellent low temperature performance, including 11C rates at -30 C and the ability to perform well down to -60 C. Excellent cycle life at room temperature has been displayed, with over 5,000 cycles being demonstrated. Good high temperature cycle life performance has also been achieved. Demonstrated improved performance with methyl propionate-containing electrolytes in large capacity prototype cells: Demonstrated the wide operating temperature range capability in large cells (12 Ah), successfully scaling up technology from 0.25 Ah size cells. Demonstrated improved performance at low temperature and good cycle life at 40 C with methyl propionate-based electrolyte containing increasing FEC content and the use of LiBOB as an additive. Utilized three-electrode cells to investigate the electrochemical characteristics of high voltage systems coupled with wide operating temperature range electrolytes: From Tafel polarization measurements on each electrode, it is evident the NMC-based cathode displays poor lithium kinetics (being the limiting electrode). The MB-based formulations containing LiBOB delivered the best rate capability at low temperature, which is attributed to improved cathode kinetics. Whereas, the use of lithium oxalate as an additive lead to the highest reversible capacity and lower irreversible losses.

  15. Low Frequency High Amplitude Temperature Oscillations in Loop Heat Pipe Operation

    NASA Technical Reports Server (NTRS)

    Ku, Jentung; Rodriquez, Jose; Simpson, Alda D. (Technical Monitor)

    2003-01-01

    This paper presents a theory that explains low frequency, high amplitude temperature oscillations in loop heat pipe (LHP) operation. Oscillations of the CC temperature with amplitudes on the order of tens of degrees Kelvin and periods on the order of hours have been observed in some LHPs during ambient testing. There are presently no satisfactory explanations for such a phenomenon in the literature. It is well-known that the operating temperature of an LHP with a single evaporator is governed by the compensation chamber (CC) temperature, which in turn is a function of the evaporator heat load, sink temperature, and ambient temperature. As the operating condition changes, the CC temperature will change during the transient but eventually reach a new steady temperature. Under certain conditions, however, the LHP never really reaches a true steady state, but instead displays an oscillatory behavior. The proposed new theory describes why low frequency, high amplitude oscillations may occur when the LHP has a low evaporator power, a low heat sink temperature (below ambient temperature), and a large thermal mass attached to the evaporator. When this condition prevails, there are some complex interactions between the CC, condenser, thermal mass and ambient. The temperature oscillation is a result of the large movement of the vapor front inside the condenser, which is caused by a change in the net evaporator power modulated by the large thermal mass through its interaction with the sink and CC. The theory agrees very well with previously published test data. Effects of various parameters on the amplitude and frequency of the temperature oscillation are also discussed.

  16. 40 CFR Table 7 to Subpart Wwww of... - Options Allowing Use of the Same Resin Across Different Operations That Use the Same Resin Type

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... . . . 1. CR/HS resins, centrifugal casting 1,2 a. CR/HS mechanical 3 48.0 b. CR/HS filament application 48... centrifugal casting 1,2 38.5 6. non-CR/HS resins, centrifugal casting 1,2 non-CR/HS manual 37.5 7. tooling... 45.9 1 If the centrifugal casting operation blows heated air through the molds, then 95...

  17. 40 CFR Table 7 to Subpart Wwww of... - Options Allowing Use of the Same Resin Across Different Operations That Use the Same Resin Type

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... . . . is . . . 1. CR/HS resins, centrifugal casting 1,2 a. CR/HS mechanical 3 48.0 b. CR/HS filament... centrifugal casting 1,2 38.5 6. non-CR/HS resins, centrifugal casting 1,2 non-CR/HS manual 37.5 7. tooling... 45.9 1 If the centrifugal casting operation blows heated air through the molds, then 95...

  18. 40 CFR Table 7 to Subpart Wwww of... - Options Allowing Use of the Same Resin Across Different Operations That Use the Same Resin Type

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... . . . is . . . 1. CR/HS resins, centrifugal casting 1 2 a. CR/HS mechanical 3 48.0 b. CR/HS filament... centrifugal casting 1 2 38.5 6. non-CR/HS resins, centrifugal casting 1 2 non-CR/HS manual 37.5 7. tooling... 45.9 1 If the centrifugal casting operation blows heated air through the molds, then 95...

  19. 40 CFR Table 7 to Subpart Wwww of... - Options Allowing Use of the Same Resin Across Different Operations That Use the Same Resin Type

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... . . . 1. CR/HS resins, centrifugal casting 1,2 a. CR/HS mechanical 3 48.0 b. CR/HS filament application 48... centrifugal casting 1,2 38.5 6. non-CR/HS resins, centrifugal casting 1,2 non-CR/HS manual 37.5 7. tooling... 45.9 1 If the centrifugal casting operation blows heated air through the molds, then 95...

  20. 40 CFR Table 7 to Subpart Wwww of... - Options Allowing Use of the Same Resin Across Different Operations That Use the Same Resin Type

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... . . . is . . . 1. CR/HS resins, centrifugal casting 1,2 a. CR/HS mechanical 3 48.0 b. CR/HS filament... centrifugal casting 1,2 38.5 6. non-CR/HS resins, centrifugal casting 1,2 non-CR/HS manual 37.5 7. tooling... 45.9 1 If the centrifugal casting operation blows heated air through the molds, then 95...

  1. Water temperature effects from simulated dam operations and structures in the Middle Fork Willamette River, western Oregon

    USGS Publications Warehouse

    Buccola, Norman L.; Turner, Daniel F.; Rounds, Stewart A.

    2016-09-14

    to the following conclusions:The existing outlets at Lookout Point Dam, because of the range of depths, allow for greater temperature control than the two existing outlets at Hills Creek Dam that are relatively deep.Temperature control at HCR through operational scenarios generally was minimal near Hills Creek Dam, but improved downstream toward the head of LOP when decreased release rates held HCR at a low lake elevation year-round.Inflows from unregulated streams between HCR and LOP helped to dilute the effects of HCR and achieve more natural stream temperatures before the MFWR entered LOP.The relative benefit of any particular scenario depended on the location in the MFWR system used to assess the potential change, with most scenarios involving changes to Hills Creek Dam being less effective with increasing downstream distance, such as downstream of DEX.To achieve as much temperature control as the most successful structural scenarios, which were able to resemble without-dam conditions for part of the year, most operational scenarios had to be free of any power-generation requirements at Lookout Point Dam.Downstream of DEX, scenarios incorporating a hypothetical floating outlet at either HCR or LOP resulted in similar temperatures, with both scenarios causing a delay in the estimated spring Chinook egg emergence by about 9–10 days compared to base-case temperature-management scenarios.

  2. Characterization and calibration of Raman based distributed temperature sensing system for 600°C operation

    NASA Astrophysics Data System (ADS)

    Mandal, Sudeep; Dekate, Sachin; Lee, Boon K.; Guida, Renato; Mondanos, Michael; Yeo, Jackson; Goranson, Marc

    2015-05-01

    Fiber optic distributed temperature sensing based on Raman scattering of light in optical fibers has become a very attractive solution for distributed temperature sensing (DTS) applications. The Raman scattered signal is independent of strain within the fiber, enabling simple packaging solutions for fiber optic temperature sensors while simultaneously improving accuracy and robustness of temperature measurements due to the lack of strain-induced errors in these measurements. Furthermore, the Raman scattered signal increases in magnitude at higher fiber temperatures, resulting in an improved SNR for high temperature measurements. Most Raman DTS instruments and fiber sensors are designed for operation up to approximately 300˚C. We will present our work in demonstrating high temperature calibration of a Raman DTS system using both Ge doped and pure silica core multi-mode optical fiber. We will demonstrate the tradeoffs involved in using each type of fiber for high temperature measurements. In addition, we will describe the challenges of measuring large temperature ranges (0 - 600˚C) with a single DTS interrogator and will demonstrate the need to customize the interrogator electronics and detector response in order to achieve reliable and repeatable high temperature measurements across a wide temperature range.

  3. Operating Temperatures of a Sodium-Cooled Exhaust Valve as Measured by a Thermocouple

    NASA Technical Reports Server (NTRS)

    Sanders, J C; Wilsted, H D; Mulcahy, B A

    1943-01-01

    Report presents the results of a thermocouple installed in the crown of a sodium-cooled exhaust valve. The valve was tested in an air-cooled engine cylinder and valve temperatures under various engine operating conditions were determined. A temperature of 1337 degrees F. was observed at a fuel-air ratio of 0.064, a brake mean effective pressure of 179 pounds per square inch, and an engine speed of 2000 r.p.m. Fuel-air ratio was found to have a large influence on valve temperature, but cooling-air pressure and variation in spark advance had little effect. An increase in engine power by change of speed or mean effective pressure increased the valve temperature. It was found that the temperature of the rear-spark-plug bushing was not a satisfactory indication of the temperature of the exhaust valve.

  4. Operating Temperatures of a Sodium-Cooled Exhaust Valve as Measured by a Thermocouple

    NASA Technical Reports Server (NTRS)

    Sanders, J. C.; Wilsted, H. D.; Mulcahy, B. A.

    1943-01-01

    A thermocouple was installed in the crown of a sodium-cooled exhaust valve. The valve was then tested in an air-cooled engine cylinder and valve temperatures under various engine operating conditions were determined. A temperature of 1337 F was observed at a fuel-air ratio of 0.064, a brake mean effective pressure of 179 pounds per square inch, and an engine speed of 2000 rpm. Fuel-air ratio was found to have a large influence on valve temperature, but cooling-air pressure and variation in spark advance had little effect. An increase in engine power by change of speed or mean effective pressure increased the valve temperature. It was found that the temperature of the rear spark-plug bushing was not a satisfactory indication of the temperature of the exhaust valve.

  5. 46 CFR 54.10-5 - Maximum allowable working pressure (reproduces UG-98).

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... section VIII of the ASME Boiler and Pressure Vessel Code, together with the effect of any combination of... operating temperature, using for each temperature the applicable allowable stress value. Note: Table...

  6. Correlation between defect transition levels and thermoelectric operational temperature of doped CrSi2

    NASA Astrophysics Data System (ADS)

    Singh, Abhishek; Pandey, Tribhuwan

    2014-03-01

    The performance of a thermoelectric material is quantified by figure of merit ZT. The challenge in achieving high ZT value requires simultaneously high thermopower, high electrical conductivity and low thermal conductivity at optimal carrier concentration. So far doping is the most versatile approach used for modifying thermoelectric properties. Previous studies have shown that doping can significantly improve the thermoelectric performance, however the tuning the operating temperature of a thermoelectric device is a main issue. Using first principles density functional theory, we report for CrSi2, a linear relationship between thermodynamic charge state transition levels of defects and temperature at which thermopower peaks. We show for doped CrSi2 that the peak of thermopower occurs at the temperature Tm, which corresponds to the position of defect transition level. Therefore, by modifying the defect transition level, a thermoelectric material with a given operational temperature can be designed. The authors thankfully acknowledge support from ADA under NpMASS.

  7. Improved cycling behavior of ZEBRA battery operated at intermediate temperature of 175 °C

    SciTech Connect

    Li, Guosheng; Lu, Xiaochuan; Kim, Jin Y.; Lemmon, John P.; Sprenkle, Vincent L.

    2014-03-01

    Operation of the sodium-nickel chloride battery at temperatures below 200°C reduces cell degradation and improves cyclability. One of the main technical issues with operating this battery at intermediate temperatures such as 175°C is the poor wettability of molten sodium on β”-alumina solid electrolyte (BASE), which causes reduced active area and limits charging. In order to overcome the poor wettability of molten sodium on BASE at 175°C, a Pt grid was applied on the anode side of the BASE using a screen printing technique. Cells with their active area increased by metallized BASEs exhibited deeper charging and stable cycling behavior.

  8. Improved cycling behavior of ZEBRA battery operated at intermediate temperature of 175 °C

    NASA Astrophysics Data System (ADS)

    Li, Guosheng; Lu, Xiaochuan; Kim, Jin Y.; Lemmon, John P.; Sprenkle, Vincent L.

    2014-03-01

    Operation of the sodium-nickel chloride battery at temperatures below 200 °C reduces cell degradation and improves cyclability. One of the main technical issues with operating this battery at intermediate temperatures such as 175 °C is the poor wettability of molten sodium on β″-alumina solid electrolyte (BASE), which causes reduced active area and limits charging. In order to overcome the poor wettability of molten sodium on BASE at 175 °C, a Pt grid was applied on the anode side of the BASE using a screen printing technique. Cells with their active area increased by metallized BASEs exhibited deeper charging and stable cycling behavior.

  9. Imaging of Flame Temperature in a Combustion Chamber of Diesel Engine at Transient Operation

    NASA Astrophysics Data System (ADS)

    Kosaka, Hidenori; Sumi, Nariaki

    In this study, the flame temperature is visualized in a newly designed optical access diesel engine in order to investigate the mechanism of soot emission at transient operation mode. This single cylinder diesel engine has hydraulic variable valve system and an optical access window instead of an exhaust valve. Optical access window has cleaned by the laser cleaning technique in which the soot on the window is vaporized by the Nd:YAG laser incident. Using this optical engine, high speed photographs of flame were taken under transient operation, and flame temperature was analyzed by two color pyrometry.

  10. Stability of a Crystal Oscillator, Type Si530, Inside and Beyond its Specified Operating Temperature Range

    NASA Technical Reports Server (NTRS)

    Patterson, Richard L.; Hammoud, Ahmad

    2011-01-01

    Data acquisition and control systems depend on timing signals for proper operation and required accuracy. These clocked signals are typically provided by some form of an oscillator set to produce a repetitive, defined signal at a given frequency. Crystal oscillators are commonly used because they are less expensive, smaller, and more reliable than other types of oscillators. Because of the inherent characteristics of the crystal, the oscillators exhibit excellent frequency stability within the specified range of operational temperature. In some cases, however, some compensation techniques are adopted to further improve the thermal stability of a crystal oscillator. Very limited data exist on the performance and reliability of commercial-off-the-shelf (COTS) crystal oscillators at temperatures beyond the manufacturer's specified operating temperature range. This information is very crucial if any of these parts were to be used in circuits designed for use in space exploration missions where extreme temperature swings and thermal cycling are encountered. This report presents the results of the work obtained on the operation of Silicon Laboratories crystal oscillator, type Si530, under specified and extreme ambient temperatures.

  11. EHL Transition Temperature Measurements on a Geostationary Operational Environmental Satellite (GOES) Filter Wheel Bearing

    NASA Technical Reports Server (NTRS)

    Jansen, Mark J.; Jones, William R., Jr.; Pepper, Stephen V.; Predmore, Roamer E.; Shogrin, Bradley A.

    2001-01-01

    The elastohydrodynamic lubrication (EHL) transition temperature was measured for a Geostationary Operational Environmental Satellite (GOES) sounder filter wheel bearing in a vacuum tribometer. Conditions included both an 89 N (20 lb.) hard and soft load, 600 rpm, temperatures between 23 C (73 F) and 85 C (185 F), and a vacuum of approximately 1.3 x 10(exp -5) Pa. Elastohydrodynamic to mixed lubrication started to occur at approximately 70 C (158 F).

  12. Nanoscopic voltage distribution of operating cascade laser devices in cryogenic temperature.

    PubMed

    Dhar, R S; Ban, D

    2016-06-01

    A nanoscopic exploratory measurement technique to measure voltage distribution across an operating semiconductor device in cryogenic temperature has been developed and established. The cross-section surface of the terahertz (THz) quantum cascade laser (QCL) has been measured that resolves the voltage distribution at nanometer scales. The electric field dissemination across the active region of the device has been attained under the device's lasing conditions at cryogenic temperature of 77 K.

  13. Defining the Operational Conditions for High Temperature Polymer Fuel Cells in Naval Environments

    DTIC Science & Technology

    2008-12-31

    benefits of both Proton Exchange Membrane Fuel Cells (PEMFCs) and phosphoric acid fuel cell technologies: a solid polymer electrolyte, the PBI ...PEMFC and phosphoric acid fuel cell technologies: a solid polymer electrolyte, the PBI membrane, but with higher temperature (160°C) operation. PBI ...high-temperature polymer fuel cell is emerging, based on phosphoric- acid -doped polybenzimidazole ( PBI ) membranes. PBI technology combines some of the

  14. Effects of operating conditions on performance of high-temperature polymer electrolyte water electrolyzer

    NASA Astrophysics Data System (ADS)

    Li, Hua; Inada, Akiko; Fujigaya, Tsuyohiko; Nakajima, Hironori; Sasaki, Kazunari; Ito, Kohei

    2016-06-01

    Effects of operating conditions of a high-temperature polymer electrolyte water electrolyzer (HT-PEWE) on the electrolysis voltage are evaluated, and the optimal conditions for a high performance are revealed. A HT-PEWE unit cell with a 4-cm2 electrode consisting of Nafion117-based catalyst-coated membrane with IrO2 and Pt/C as the oxygen and hydrogen evolution catalysts is fabricated, and its electrolysis voltage and high-frequency resistance are assessed. The cell temperature and pressure are controlled at 80-130 °C and 0.1-0.5 MPa, respectively. It is observed that increasing the temperature at a constant pressure of 0.1 MPa does not increase the ohmic overvoltage of the cell; however, it does increase the concentration overvoltage. It is also found that the increase in the overvoltage resulting from the rise in the temperature can be suppressed by elevating the pressure. When operating the cell at a temperature of 100 °C, pressure greater than 0.1 MPa suppresses the overvoltage, and so does pressures greater than 0.3 MPa at 130 °C. This behavior suggests that keeping the water in a liquid water phase by increasing the pressure is critical for operating PEWEs at high temperatures.

  15. A Rapid Method for Optimizing Running Temperature of Electrophoresis through Repetitive On-Chip CE Operations

    PubMed Central

    Kaneda, Shohei; Ono, Koichi; Fukuba, Tatsuhiro; Nojima, Takahiko; Yamamoto, Takatoki; Fujii, Teruo

    2011-01-01

    In this paper, a rapid and simple method to determine the optimal temperature conditions for denaturant electrophoresis using a temperature-controlled on-chip capillary electrophoresis (CE) device is presented. Since on-chip CE operations including sample loading, injection and separation are carried out just by switching the electric field, we can repeat consecutive run-to-run CE operations on a single on-chip CE device by programming the voltage sequences. By utilizing the high-speed separation and the repeatability of the on-chip CE, a series of electrophoretic operations with different running temperatures can be implemented. Using separations of reaction products of single-stranded DNA (ssDNA) with a peptide nucleic acid (PNA) oligomer, the effectiveness of the presented method to determine the optimal temperature conditions required to discriminate a single-base substitution (SBS) between two different ssDNAs is demonstrated. It is shown that a single run for one temperature condition can be executed within 4 min, and the optimal temperature to discriminate the SBS could be successfully found using the present method. PMID:21845077

  16. A combined experimental and numerical approach for the control and monitoring of the SPES target during operation at high temperature

    NASA Astrophysics Data System (ADS)

    Ballan, Michele; Manzolaro, Mattia; Meneghetti, Giovanni; Andrighetto, Alberto; Monetti, Alberto; Bisoffi, Giovanni; Prete, Gianfranco

    2016-06-01

    The SPES project at INFN-LNL aims at the production of neutron-rich Radioactive Ion Beams (RIBs) using the ISOL (Isotope Separation On Line) technique. A 40 MeV 200 μA proton beam will directly impinge a uranium carbide target, generating approximately 1013 fissions per second. The target system is installed under vacuum inside a water-cooled chamber, and have to maintain high working temperatures, close to 2000 °C. During operation the proton beam provides the heating power required to keep the target at the desired temperature level. As a consequence, its characteristics have to be strictly controlled in order to avoid undesired overheating. According to the original design of the control system, the proton beam can be suddenly interrupted in case of out of range vacuum or cooling water flow levels. With the aim to improve the reliability of the control system a set of temperature sensors has been installed close to the target. Their types and installation positions were defined taking into consideration the detailed information coming from a dedicated thermal-electric model that allowed to investigate the most critical and inaccessible target hot-spots. This work is focused on the definition and experimental validation of the aforementioned numerical model. Its results were used to appropriately install two type C thermocouples, a PT100 thermo-resistance and a residual primary beam current detector. In addition the numerical model will be used for the definition of appropriate thresholds for each installed temperature sensor, since it allows to define a relationship between the locally measured values with the overall calculated temperature field. In case of over temperatures the monitoring system will send warning signals or in case interrupt the proton beam.

  17. The effect of operating temperature on open, multimegawatt space power systems

    SciTech Connect

    Edenburn, M.W.

    1987-01-01

    This study addresses reactor powered and combustion powered multimegawatt, burst mode, space power systems to evaluate the effect turbine inlet temperature will have on their performance and mass. Both systems will provide power to space based antiballistic missile weapons that require hydrogen for cooling, and both use this hydrogen coolant as a working fluid or as a fuel for power generation. The quantity of hydrogen needed for weapon cooling increases as the weapon's cooling load increases and as weapon coolant outlet temperature decreases. Also, the hydrogen needed by the turbines in both power systems increases as turbine inlet temperature decreases. When weapon cooling loads are above 40% to 50% of weapon power and weapon coolant outlet temperature is below 300 K to 400 K, the weapon needs more hydrogen than the turbine in either the reactor or combustion powered systems using turbine inlet temperatures consistent with current material technology. There is therefore very little system mass reduction to be gained by operating a burst mode power system at a turbine inlet temperature above present material temperature limits unless the weapon's cooling load is below 40% to 50% or coolant outlet temperature is above 300 K to 400 K. Furthermore, the combustion system's mass increases as turbine inlet temperature increases because oxygen inventory increases with increased turbine inlet temperature.

  18. Temperature dependence of resonance characteristics of silicon resonators and thermal stability improvement by differential operation method

    NASA Astrophysics Data System (ADS)

    Sana, Amrita Kumar; Jun, Maeda; Yokoyama, Shuhei; Amemiya, Yoshiteru; Yokoyama, Shin

    2017-04-01

    In this paper, we describe the mechanism and solution for dominating temperature effects on refractive-index-based Si optical resonator sensors such as ring resonator and photonic crystal resonator sensors. The temperature change affects the silicon refractive index and also the resonator mechanical shape. As a result, it is reported that the refractive index change is marked, whereas the mechanical deformation effect is negligible. We also demonstrated that the differential operation is effective for suppressing the temperature effect for Si ring resonator sensors.

  19. Optical properties and electronic requirements for low-temperature operation of yellow semiconductor LEDs

    NASA Astrophysics Data System (ADS)

    Lee, Susanne M.; Mueller, Eduard K.; Van de Workeen, Brian C.; Mueller, Otward M.

    2001-05-01

    In such LED applications as lighting, it is desirable to have the highest light output for the lowest power consumption. This paper investigates the optical properties and electronic requirements of a commercially available yellow LED as a function of temperature from ambient to liquid nitrogen temperatures. It was found that the illuminance increased by almost an order of magnitude, producing much higher light output at the same diode current. However, the operating voltage increased, increasing the overall power consumption slightly. The efficiency (light-watt output to electrical watts consumed) of the LED, though, improved by a factor of more than three. This, combined with the enhanced light output, compensates for the small increase in power consumption and added cooling costs. These improvements further translate into a comparable increase in the lifetime of the LEDs. In general, each ten-degree reduction in temperature corresponds to a doubling of the lifetime of semiconductor devices. It was also found that the maximum operating current increased significantly at liquid nitrogen temperatures over that at ambient temperatures. Lastly, the emitted wavelength range shifted to shorter values in addition to the significant increase in brightness. Thus, a yellow- colored LED at room temperature gave off a much brighter yellow-green-white color at liquid nitrogen temperatures.

  20. Validation of a weather forecast model at radiance level against satellite observations allowing quantification of temperature, humidity, and cloud-related biases

    NASA Astrophysics Data System (ADS)

    Bani Shahabadi, Maziar; Huang, Yi; Garand, Louis; Heilliette, Sylvain; Yang, Ping

    2016-09-01

    An established radiative transfer model (RTM) is adapted for simulating all-sky infrared radiance spectra from the Canadian Global Environmental Multiscale (GEM) model in order to validate its forecasts at the radiance level against Atmospheric InfraRed Sounder (AIRS) observations. Synthetic spectra are generated for 2 months from short-term (3-9 h) GEM forecasts. The RTM uses a monthly climatological land surface emissivity/reflectivity atlas. An updated ice particle optical property library was introduced for cloudy radiance calculations. Forward model brightness temperature (BT) biases are assessed to be of the order of ˜1 K for both clear-sky and overcast conditions. To quantify GEM forecast meteorological variables biases, spectral sensitivity kernels are generated and used to attribute radiance biases to surface and atmospheric temperatures, atmospheric humidity, and clouds biases. The kernel method, supplemented with retrieved profiles based on AIRS observations in collocation with a microwave sounder, achieves good closure in explaining clear-sky radiance biases, which are attributed mostly to surface temperature and upper tropospheric water vapor biases. Cloudy-sky radiance biases are dominated by cloud-induced radiance biases. Prominent GEM biases are identified as: (1) too low surface temperature over land, causing about -5 K bias in the atmospheric window region; (2) too high upper tropospheric water vapor, inducing about -3 K bias in the water vapor absorption band; (3) too few high clouds in the convective regions, generating about +10 K bias in window band and about +6 K bias in the water vapor band.

  1. High-Operating-Temperature Direct Ink Writing of Mesoscale Eutectic Architectures.

    PubMed

    Boley, J William; Chaudhary, Kundan; Ober, Thomas J; Khorasaninejad, Mohammadreza; Chen, Wei Ting; Hanson, Erik; Kulkarni, Ashish; Oh, Jaewon; Kim, Jinwoo; Aagesen, Larry K; Zhu, Alexander Y; Capasso, Federico; Thornton, Katsuyo; Braun, Paul V; Lewis, Jennifer A

    2017-02-01

    High-operating-temperature direct ink writing (HOT-DIW) of mesoscale architectures that are composed of eutectic silver chloride-potassium chloride. The molten ink undergoes directional solidification upon printing on a cold substrate. The lamellar spacing of the printed features can be varied between approximately 100 nm and 2 µm, enabling the manipulation of light in the visible and infrared range.

  2. Ice formation in PEM fuel cells operated isothermally at sub-freezing temperatures

    SciTech Connect

    Mukundan, Rangachary; Luhan, Roger W; Davey, John R; Spendelow, Jacob S; Borup, Rodney L; Hussey, Daniel S; Jacobson, David L; Arif, Muhammad

    2009-01-01

    The effect of MEA and GDL structure and composition on the performance of single-PEM fuel cells operated isothermally at subfreezing temperatures is presented. The cell performance and durability are not only dependent on the MEA/GDL materials used but also on their interfaces. When a cell is operated isothermally at sub-freezing temperatures in constant current mode, the water formation due to the current density initially hydrates the membrane/ionomer and then forms ice in the catalyst layer/GDL. An increase in high frequency resistance was also observed in certain MEAs where there is a possibility of ice formation between the catalyst layer and GDL leading to a loss in contact area. The total water/ice holding capacity for any MEA was lower at lower temperatures and higher current densities. The durability of MEAs subjected to multiple isothermal starts was better for LANL prepared MEAs as compared to commercial MEAs, and cloth GDLs when compared to paper GDLs. The ice formation was monitored using high-resolution neutron radiography and was found to be concentrated near the cathode catalyst layer. However, there was significant ice formation in the GDLs especially at the higher temperature ({approx} -10 C) and lower current density (0.02 A/cm{sup 2}) operations. These results are consistent with the longer-term durability observations that show more severe degradation at the lower temperatures.

  3. A simple, battery-operated, temperature-controlled cuvette for respiration measurements.

    PubMed

    Hubbard, R M; Ryan, M G; Lukens, D L

    1995-03-01

    We designed a simple, portable, battery-operated, temperature-controlled cuvette to measure respiration of small samples of plant tissue in the field. The cuvette is built around a peltier cell and is controlled with a data logger. The cuvette maintained sample temperature within 0.5 degrees C over a temperature range of 5 to 45 degrees C and operated for 6-8 h from a 12 V 105 ampere-hour "deep-cycle" battery. Based on measurements with this cuvette, we found that, at 15 degrees C, CO(2) efflux from dark respiration of white pine (Pinus strobus L.) foliage was 40% greater during the day than at night.

  4. Thermal disconnect for high-temperature batteries

    DOEpatents

    Jungst, Rudolph George; Armijo, James Rudolph; Frear, Darrel Richard

    2000-01-01

    A new type of high temperature thermal disconnect has been developed to protect electrical and mechanical equipment from damage caused by operation at extreme temperatures. These thermal disconnects allow continuous operation at temperatures ranging from 250.degree. C. to 450.degree. C., while rapidly terminating operation at temperatures 50.degree. C. to 150.degree. C. higher than the continuous operating temperature.

  5. Multi-color tunneling quantum dot infrared photodetectors operating at room temperature

    NASA Astrophysics Data System (ADS)

    Ariyawansa, G.; Perera, A. G. U.; Su, X. H.; Chakrabarti, S.; Bhattacharya, P.

    2007-04-01

    Quantum dot structures designed for multi-color infrared detection and high temperature (or room temperature) operation are demonstrated. A novel approach, tunneling quantum dot (T-QD), was successfully demonstrated with a detector that can be operated at room temperature due to the reduction of the dark current by blocking barriers incorporated into the structure. Photoexcited carriers are selectively collected from InGaAs quantum dots by resonant tunneling, while the dark current is blocked by AlGaAs/InGaAs tunneling barriers placed in the structure. A two-color tunneling-quantum dot infrared photodetector (T-QDIP) with photoresponse peaks at 6 μm and 17 μm operating at room temperature will be discussed. Furthermore, the idea can be used to develop terahertz T-QD detectors operating at high temperatures. Successful results obtained for a T-QDIP designed for THz operations are presented. Another approach, bi-layer quantum dot, uses two layers of InAs quantum dots (QDs) with different sizes separated by a thin GaAs layer. The detector response was observed at three distinct wavelengths in short-, mid-, and far-infrared regions (5.6, 8.0, and 23.0 μm). Based on theoretical calculations, photoluminescence and infrared spectral measurements, the 5.6 and 23.0 μm peaks are connected to the states in smaller QDs in the structure. The narrow peaks emphasize the uniform size distribution of QDs grown by molecular beam epitaxy. These detectors can be employed in numerous applications such as environmental monitoring, spectroscopy, medical diagnosis, battlefield-imaging, space astronomy applications, mine detection, and remote-sensing.

  6. EFFECT OF GEOMETRY AND OPERATING PARAMETERS ON SIMULATED SOFC STACK TEMPERATURE UNIFORMITY

    SciTech Connect

    Koeppel, Brian J.; Lai, Canhai; Khaleel, Mohammad A.

    2011-08-10

    A uniform temperature field is desirable in the solid oxide fuel cell stack to avoid local hot regions that contribute to material degradation, thermal stresses, and differences in electrochemical performance. Various geometric and operational design changes were simulated by numerical modeling of co-flow and counter-flow multi-cell stacks, and the effects on stack maximum temperature, stack temperature difference, and maximum cell temperature difference were characterized. The results showed that 40-60% on-cell steam reforming of methane and a reduced reforming rate of 25-50% of the nominal rate was beneficial for a more uniform temperature field. Fuel exhaust recycling up to 30% was shown to be advantageous for reforming fuels and co-flow stacks with hydrogen fuel, but counter-flow stacks with hydrogen fuel showed higher temperature differences. Cells with large aspect ratios showed a more uniform temperature response due to either the strong influence of the inlet gas temperatures or the greater thermal exchange with the furnace boundary condition. Improved lateral heat spreading with thicker interconnects was demonstrated, but greater improvements towards a uniform thermal field for the same amount of interconnect mass could be achieved using thicker heat spreader plates appropriately distributed along the stack height.

  7. Improved operation of graded-channel SOI nMOSFETs down to liquid helium temperature

    NASA Astrophysics Data System (ADS)

    Pavanello, Marcelo Antonio; de Souza, Michelly; Ribeiro, Thales Augusto; Martino, João Antonio; Flandre, Denis

    2016-11-01

    This paper presents the operation of Graded-Channel (GC) Silicon-On-Insulator (SOI) nMOSFETs at low temperatures down to liquid helium temperature in comparison to standard uniformly doped transistors. Devices from two different technologies have been measured and show that the mobility increase rate with temperature for GC SOI transistors is similar to uniformly doped devices for temperatures down to 90 K. However, at liquid helium temperature the rate of mobility increase is larger in GC SOI than in standard devices because of the different mobility scattering mechanisms. The analog properties of GC SOI devices have been investigated down to 4.16 K and show that because of its better transconductance and output conductance, an intrinsic voltage gain improvement with temperature is also obtained for devices in the whole studied temperature range. GC devices are also capable of reducing the impact ionization due to the high electric field in the drain region, increasing the drain breakdown voltage of fully-depleted SOI MOSFETs at any studied temperature and the kink voltage at 4.16 K.

  8. High-Operating Temperature HgCdTe: A Vision for the Near Future

    NASA Astrophysics Data System (ADS)

    Lee, D.; Carmody, M.; Piquette, E.; Dreiske, P.; Chen, A.; Yulius, A.; Edwall, D.; Bhargava, S.; Zandian, M.; Tennant, W. E.

    2016-09-01

    We review recent advances in the HgCdTe material quality and detector performance achieved at Teledyne using molecular beam epitaxy growth and the double-layer planar hetero-junction (DLPH) detector architecture. By using an un-doped, fully depleted absorber, Teledyne's DLPH architecture can be extended for use in high operating temperatures and other applications. We assess the potential achievable performance for long wavelength infrared (LWIR) hetero-junction p-lightly-doped n or p-intrinsic- n (p-i-n) detectors based on recently reported results for 10.7 μm cutoff 1 K × 1 K focal plane arrays (FPAs) tested at temperatures down to 30 K. Variable temperature dark current measurements show that any Shockley-Read-Hall currents in the depletion region of these devices have lifetimes that are reproducibly greater than 100 ms. Under the assumption of comparable lifetimes at higher temperatures, it is predicted that fully-depleted background radiation-limited performance can be expected for 10- μm cutoff detectors from room temperature to well below liquid nitrogen temperatures, with room-temperature dark current nearly 400 times lower than predicted by Rule 07. The hetero-junction p-i-n diode is shown to have numerous other significant potential advantages including minimal or no passivation requirements for pBn-like processing, low 1/ f noise, compatibility with small pixel pitch while maintaining high modulation transfer function, low crosstalk and good quantum efficiency. By appropriate design of the FPA dewar shielding, analysis shows that dark current can theoretically be further reduced below the thermal equilibrium radiative limit. Modeling shows that background radiation-limited LWIR HgCdTe operating with f/1 optics has the potential to operate within √2 of background-limited performance at 215 K. By reducing the background radiation by 2/3 using novel shielding methods, operation with a single-stage thermo-electric-cooler may be possible. If the

  9. Mixing it up in the Makassar Strait: Seasonal Reconstructions from Corals of Sea Surface Temperature and Salinity Allow for Records of Source Water Mixing in the Makassar Strait

    NASA Astrophysics Data System (ADS)

    Murty, S. A.; Goodkin, N.; Halide, H.; Natawidjaja, D. H.; Suwargadi, B. W.; Suprinhanto, I.; Prayudi, D.

    2015-12-01

    The Indonesian seas provide a maze of passages through which relatively warm and fresh water flows from the equatorial Pacific to the Indian Ocean forming the Indonesian Throughflow (ITF). As it flows, the ITF provides a transport pathway affecting heat and buoyancy fluxes throughout the region, interacting with both the Asian monsoon and the El Niño Southern Oscillation (ENSO). The present and past behavior of the ITF is therefore one of the keys to understanding regional and global climate variability. Past ITF behavior has been previously recorded in massive coral colonies, which serve as continuous, high-resolution climate archives because of their high linear extension rates and annual banding pattern. Here we present Sr/Ca-SST and δ18O-SSS calibrations from three Porites spp. coral colonies located in the southern Makassar Strait, through which roughly 75-80% of all ITF waters flow. At interannual timescales, we find that in all three corals Sr/Ca significantly (all p-values<0.05) correlates with sea surface temperature (SST) during the SE monsoon from July to September, while δ18O is correlated with sea surface salinity (SSS) during the NW monsoon from December to March (all p-values<0.05). HADI SST and SODA SSS instrumental temperature-salinity diagrams from our coral sites indicate that the southern Makassar Strait is a region of surface seawater mixing between end member water masses of the ITF during the SE monsoon. During the NW monsoon, however, end members of the South China Sea Throughflow (SCSTF) instead mix in the surface waters. The strength of our interannual calibrations suggests that it may be possible to reconstruct the ITF and SCSTF surface mixing patterns during their respective monsoon seasons. To preliminarily assess this, we present 150-year seasonally resolved records of Sr/Ca and δ18O to reconstruct surface water mixing in the southern Makassar Strait.

  10. Study of the operation temperature in the spin-exchange relaxation free magnetometer

    SciTech Connect

    Fang, Jiancheng; Li, Rujie Duan, Lihong; Chen, Yao; Quan, Wei

    2015-07-15

    We study the influence of the cell temperature on the sensitivity of the spin-exchange relaxation free (SERF) magnetometer and analyze the possibility of operating at a low temperature. Utilizing a 25 × 25 × 25 mm{sup 3} Cs vapor cell with a heating temperature of 85 {sup ∘}C, which is almost half of the value of potassium, we obtain a linewidth of 1.37 Hz and achieve a magnetic field sensitivity of 55 fT/Hz{sup 1/2} in a single channel. Theoretical analysis shows that fundamental sensitivity limits of this device with an active volume of 1 cm{sup 3} could approach 1 fT/Hz{sup 1/2}. Taking advantage of the higher saturated vapor pressure, SERF magnetometer based on Cs opens up the possibility for low cost and portable sensors and is particularly appropriate for lower temperature applications.

  11. Study of the operation temperature in the spin-exchange relaxation free magnetometer.

    PubMed

    Fang, Jiancheng; Li, Rujie; Duan, Lihong; Chen, Yao; Quan, Wei

    2015-07-01

    We study the influence of the cell temperature on the sensitivity of the spin-exchange relaxation free (SERF) magnetometer and analyze the possibility of operating at a low temperature. Utilizing a 25 × 25 × 25 mm(3) Cs vapor cell with a heating temperature of 85 °C, which is almost half of the value of potassium, we obtain a linewidth of 1.37 Hz and achieve a magnetic field sensitivity of 55 fT/Hz(1/2) in a single channel. Theoretical analysis shows that fundamental sensitivity limits of this device with an active volume of 1 cm(3) could approach 1 fT/Hz(1/2). Taking advantage of the higher saturated vapor pressure, SERF magnetometer based on Cs opens up the possibility for low cost and portable sensors and is particularly appropriate for lower temperature applications.

  12. Room temperature operation of GaSb-based resonant tunneling diodes by prewell injection

    NASA Astrophysics Data System (ADS)

    Pfenning, Andreas; Knebl, Georg; Hartmann, Fabian; Weih, Robert; Bader, Andreas; Emmerling, Monika; Kamp, Martin; Höfling, Sven; Worschech, Lukas

    2017-01-01

    We present room temperature resonant tunneling of GaSb/AlAsSb double barrier resonant tunneling diodes with pseudomorphically grown prewell emitter structures comprising the ternary compound semiconductors GaInSb and GaAsSb. At room temperature, resonant tunneling is absent for diode structures without prewell emitters. The incorporation of Ga0.84In0.16Sb and GaAs0.05Sb0.95 prewell emitters leads to room temperature resonant tunneling with peak-to-valley current ratios of 1.45 and 1.36 , respectively. The room temperature operation is attributed to the enhanced Γ-L-valley energy separation and consequently depopulation of L-valley states in the conduction band of the ternary compound emitter prewell with respect to bulk GaSb.

  13. Investigation of high temperature operation of proton exchange membrane fuel cells

    NASA Astrophysics Data System (ADS)

    Adjemian, Kevork Tro

    Proton exchange membrane fuel cells (PEMFCs) have garnered much attention in the media over the past years as they can provide a clean, environmentally friendly alternative to internal combustion engines. PEMFCs also have the flexibility to operate on many different types of fuels, thereby diminishing our reliance on foreign oil. PEMFCs, however, suffer from many drawbacks which need to be overcome before mass production becomes viable. One drawback is the expense of the fuel cell system, costing several times more than existing technologies. Another problem is that if the fuel cell is running on reformed fuels, trace amounts of carbon monoxide (10 ppm) in the hydrogen gas stream will completely poison the anode electrocatalyst, killing the PEMFC. Also, as a lot of waste heat is generated, a very elaborate cooling system needs to be used, making the overall system more expensive and complex. A possible solution to both the carbon monoxide poisoning and thermal management of a PEMFC is to elevate its operating temperature above 100°C. Unfortunately, current state-of-the-art electrolytes used in PEMFCs, i.e. Nafion 115, rely on water for the conduction of protons and by elevating the temperature, water loss occurs due to evaporation resulting in inadequate PEMFC performance. This thesis delves into the modification of Nafion and similar electrolytes to permit PEMFC operation above 100°C. This was accomplished by impregnating the pores of the Nafion with hydrophilic inorganic materials-silicon oxide via sol-gel processing and various inorganic particles. By performing these modifications to the various electrolytes, several composite membranes performed exceptionally well at an operating temperature of 130°C and demonstrated carbon monoxide tolerance of up to 500 ppm. In addition, a theory on how these materials help improve the water management characteristics of Nafion was developed, laying the foundation for the development of a completely novel membrane to

  14. S∧4 Reactor: Operating Lifetime and Estimates of Temperature and Burnup Reactivity Coefficients

    NASA Astrophysics Data System (ADS)

    King, Jeffrey C.; El-Genk, Mohamed S.

    2006-01-01

    The S∧4 reactor has a sectored, Mo-14%Re solid core for avoidance of single point failures in reactor cooling and Closed Brayton Cycle (CBC) energy conversion. The reactor is loaded with UN fuel, cooled with a He-Xe gas mixture at ~1200 K and operates at steady thermal power of 550 kW. Following a launch abort accident, the axial and radial BeO reflectors easily disassemble upon impact so that the bare reactor is subcriticial when submerged in wet sand or seawater and the core voids are filled with seawater. Spectral Shift Absorber (SSA) additives have been shown to increase the UN fuel enrichment and significantly reduce the total mass of the reactor. This paper investigates the effects of SSA additions on the temperature and burnup reactivity coefficients and the operational lifetime of the S∧4 reactor. SSAs slightly decrease the temperature reactivity feedback coefficient, but significantly increase the operating lifetime by decreasing the burnup reactivity coefficient. With no SSAs, fuel enrichment is only 58.5 wt% and the estimated operating lifetime is the shortest (7.6 years) with the highest temperature and burnup reactivity feedback coefficients (-0.2709 ¢/K and -1.3470 $/atom%). With europium-151 and gadolinium-155 additions, the enrichment (91.5 and 94 wt%) and operating lifetime (9.9 and 9.8 years) of the S∧4 reactor are the highest while the temperature and burnup reactivity coefficients (-0.2382 and -0.2447 ¢/K -0.9073 and 0.8502 $/atom%) are the lowest.

  15. Metabolic response to air temperature and wind in day-old mallards and a standard operative temperature scale.

    PubMed

    Bakken, G S; Reynolds, P S; Kenow, K P; Korschgen, C E; Boysen, A F

    1999-01-01

    Most duckling mortality occurs during the week following hatching and is often associated with cold, windy, wet weather and scattering of the brood. We estimated the thermoregulatory demands imposed by cold, windy weather on isolated 1-d-old mallard (Anas platyrhynchos) ducklings resting in cover. We measured O2 consumption and evaporative water loss at air temperatures from 5 degrees to 25 degrees C and wind speeds of 0.1, 0.2, 0.5, and 1.0 m/s. Metabolic heat production increased as wind increased or temperature decreased but was less sensitive to wind than that of either adult passerines or small mammals. Evaporative heat loss ranged from 5% to 17% of heat production. Evaporative heat loss and the ratio of evaporative heat loss to metabolic heat production was significantly lower in rest phase. These data were used to define a standard operative temperature (Tes) scale for night or heavy overcast conditions. An increase of wind speed from 0.1 to 1 m/s decreased Tes by 3 degrees -5 degrees C.

  16. Metabolic response to air temperature and wind in day-old mallards and a standard operative temperature scale

    USGS Publications Warehouse

    Bakken, G.S.; Reynolds, P.S.; Kenow, K.P.; Korschgen, C.E.; Boysen, A.F.

    1999-01-01

    Most duckling mortality occurs during the week following hatching and is often associated with cold, windy, wet weather and scattering of the brood. We estimated the thermoregulatory demands imposed by cold, windy weather on isolated 1-d-old mallard (Anas platyrhynchos) ducklings resting in cover. We measured O-2 consumption and evaporative water loss at air temperatures from 5 degrees to 25 degrees C and wind speeds of 0.1, 0.2, 0.5, and 1.0 mis. Metabolic heat production increased as wind increased or temperature decreased but was less sensitive to wind than that of either adult passerines or small mammals. Evaporative heat loss ranged from 5% to 17% of heat production. Evaporative heal loss and the ratio of evaporative heat loss to metabolic heat production was significantly lower in rest phase. These data were used to define a standard operative temperature (T-es) scale for night or heavy overcast conditions. An increase of wind speed from 0.1 to 1 mis decreased T-es by 3 degrees-5 degrees C.

  17. Assessment of SOI AND Gate, Type CHT-7408, for Operation in Extreme Temperature Environments

    NASA Technical Reports Server (NTRS)

    Patterson, Richard; Hammoud, Ahmad; Dones, Keishla Rivera

    2009-01-01

    Electronic parts based on silicon-on-insulator (SOI) technology are finding widespread applications due to their ability to operate in harsh environments and the benefits they offer as compared to their silicon counterparts. Due to their construction, they are tailored for high temperature operation and show good tolerance to radiation events. In addition, their inherent design lessens the formation of parasitic junctions, thereby reducing leakage currents, decreasing power consumption, and enhancing speed. These devices are typically rated in temperature capability from -55 C to about +225 C, and their characteristics over this temperature range are documented in data sheets. Since electronics in some of NASA space exploration missions are required to operate under extreme temperature conditions, both cold and hot, their characteristic behavior within the full temperature spectrum must be determined to establish suitability for use in space applications. The effects of extreme temperature exposure on the performance of a new commercial-off-the-shelf (COTS) SOI AND gate device were evaluated in this work. The high temperature, quad 2-inputs AND gate device, which was recently introduced by CISSOID, is fabricated using a CMOS SOI process. Some of the specifications of the CHT-7408 chip are listed in a table. By supplying a constant DC voltage to one gate input and a 10 kHz square wave into the other associated gate input, the chip was evaluated in terms of output response, output rise (t(sub r)) and fall times (tf), and propagation delays (using a 50% level between input and output during low to high (tPLH) and high to low (tPHL) transitions). The supply current of the gate circuit was also obtained. These parameters were recorded at various test temperatures between -195 C and +250 C using a Sun Systems environmental chamber programmed at a temperature rate of change of 10 C/min. In addition, the effects of thermal cycling on this chip were determined by exposing

  18. High-temperature operation of broadband bidirectional terahertz quantum-cascade lasers

    PubMed Central

    Khanal, Sudeep; Gao, Liang; Zhao, Le; Reno, John L.; Kumar, Sushil

    2016-01-01

    Terahertz quantum cascade lasers (QCLs) with a broadband gain medium could play an important role for sensing and spectroscopy since then distributed-feedback schemes could be utilized to produce laser arrays on a single semiconductor chip with wide spectral coverage. QCLs can be designed to emit at two different frequencies when biased with opposing electrical polarities. Here, terahertz QCLs with bidirectional operation are developed to achieve broadband lasing from the same semiconductor chip. A three-well design scheme with shallow-well GaAs/Al0.10Ga0.90As superlattices is developed to achieve high-temperature operation for bidirectional QCLs. It is shown that shallow-well heterostructures lead to optimal quantum-transport in the superlattice for bidirectional operation compared to the prevalent GaAs/Al0.15Ga0.85As material system. Broadband lasing in the frequency range of 3.1–3.7 THz is demonstrated for one QCL design, which achieves maximum operating temperatures of 147 K and 128 K respectively in opposing polarities. Dual-color lasing with large frequency separation is demonstrated for a second QCL, that emits at ~3.7 THz and operates up to 121 K in one polarity, and at ~2.7 THz up to 105 K in the opposing polarity. These are the highest operating temperatures achieved for broadband terahertz QCLs at the respective emission frequencies, and could lead to commercial development of broadband terahertz laser arrays. PMID:27615416

  19. High-temperature operation of broadband bidirectional terahertz quantum-cascade lasers

    SciTech Connect

    Khanal, Sudeep; Gao, Liang; Zhao, Le; Reno, John L.; Kumar, Sushil

    2016-09-12

    Terahertz quantum cascade lasers (QCLs) with a broadband gain medium could play an important role for sensing and spectroscopy since then distributed-feedback schemes could be utilized to produce laser arrays on a single semiconductor chip with wide spectral coverage. QCLs can be designed to emit at two different frequencies when biased with opposing electrical polarities. Here, we develop terahertz QCLs with bidirectional operation to achieve broadband lasing from the same semiconductor chip. A three-well design scheme with shallow-well GaAs/Al0.10Ga0.90As superlattices is developed to achieve high-temperature operation for bidirectional QCLs. It is shown that shallow-well heterostructures lead to optimal quantum-transport in the superlattice for bidirectional operation compared to the prevalent GaAs/Al0.15Ga0.85As material system. Furthermore, broadband lasing in the frequency range of 3.1–3.7 THz is demonstrated for one QCL design, which achieves maximum operating temperatures of 147 K and 128 K respectively in opposing polarities. Dual-color lasing with large frequency separation is demonstrated for a second QCL, that emits at ~3.7 THz and operates up to 121 K in one polarity, and at ~2.7 THz up to 105 K in the opposing polarity. Finally, these are the highest operating temperatures achieved for broadband terahertz QCLs at the respective emission frequencies, and could lead to commercial development of broadband terahertz laser arrays.

  20. High-temperature operation of broadband bidirectional terahertz quantum-cascade lasers

    DOE PAGES

    Khanal, Sudeep; Gao, Liang; Zhao, Le; ...

    2016-09-12

    Terahertz quantum cascade lasers (QCLs) with a broadband gain medium could play an important role for sensing and spectroscopy since then distributed-feedback schemes could be utilized to produce laser arrays on a single semiconductor chip with wide spectral coverage. QCLs can be designed to emit at two different frequencies when biased with opposing electrical polarities. Here, we develop terahertz QCLs with bidirectional operation to achieve broadband lasing from the same semiconductor chip. A three-well design scheme with shallow-well GaAs/Al0.10Ga0.90As superlattices is developed to achieve high-temperature operation for bidirectional QCLs. It is shown that shallow-well heterostructures lead to optimal quantum-transport inmore » the superlattice for bidirectional operation compared to the prevalent GaAs/Al0.15Ga0.85As material system. Furthermore, broadband lasing in the frequency range of 3.1–3.7 THz is demonstrated for one QCL design, which achieves maximum operating temperatures of 147 K and 128 K respectively in opposing polarities. Dual-color lasing with large frequency separation is demonstrated for a second QCL, that emits at ~3.7 THz and operates up to 121 K in one polarity, and at ~2.7 THz up to 105 K in the opposing polarity. Finally, these are the highest operating temperatures achieved for broadband terahertz QCLs at the respective emission frequencies, and could lead to commercial development of broadband terahertz laser arrays.« less

  1. High-temperature operation of broadband bidirectional terahertz quantum-cascade lasers

    NASA Astrophysics Data System (ADS)

    Khanal, Sudeep; Gao, Liang; Zhao, Le; Reno, John L.; Kumar, Sushil

    2016-09-01

    Terahertz quantum cascade lasers (QCLs) with a broadband gain medium could play an important role for sensing and spectroscopy since then distributed-feedback schemes could be utilized to produce laser arrays on a single semiconductor chip with wide spectral coverage. QCLs can be designed to emit at two different frequencies when biased with opposing electrical polarities. Here, terahertz QCLs with bidirectional operation are developed to achieve broadband lasing from the same semiconductor chip. A three-well design scheme with shallow-well GaAs/Al0.10Ga0.90As superlattices is developed to achieve high-temperature operation for bidirectional QCLs. It is shown that shallow-well heterostructures lead to optimal quantum-transport in the superlattice for bidirectional operation compared to the prevalent GaAs/Al0.15Ga0.85As material system. Broadband lasing in the frequency range of 3.1–3.7 THz is demonstrated for one QCL design, which achieves maximum operating temperatures of 147 K and 128 K respectively in opposing polarities. Dual-color lasing with large frequency separation is demonstrated for a second QCL, that emits at ~3.7 THz and operates up to 121 K in one polarity, and at ~2.7 THz up to 105 K in the opposing polarity. These are the highest operating temperatures achieved for broadband terahertz QCLs at the respective emission frequencies, and could lead to commercial development of broadband terahertz laser arrays.

  2. Influence of gadolinium doping on the structure and defects of ceria under fuel cell operating temperature

    SciTech Connect

    Acharya, S. A. Gaikwad, V. M.; Sathe, V.; Kulkarni, S. K.

    2014-03-17

    Correlation between atomic positional shift, oxygen vacancy defects, and oxide ion conductivity in doped ceria system has been established in the gadolinium doped ceria system from X-ray diffraction (XRD) and Raman spectroscopy study at operating temperature (300–600 °C) of Intermediate Temperature Solid Oxide Fuel Cell (IT-SOFC). High temperature XRD data are used to quantify atomic positional shift from mean position with temperature. The Raman spectroscopy study shows additional vibration modes related to ordering of defect spaces (Gd{sub Ce}{sup ′}−V{sub o}{sup ••}){sup *} and (2Gd{sub Ce}{sup ′}−V{sub o}{sup ••}){sup x} generated due to association of oxygen vacancies and reduced cerium or dopant cations site (Gd{sup 3+}), which disappear at 450 °C; indicating oxygen vacancies dissociation from the defect complex. The experimental evidences of cation-anion positional shifting and oxygen vacancies dissociation from defect complex in the IT-SOFC operating temperature are discussed to correlate with activation energy for ionic conductivity.

  3. Operation of a Giant Magnetoresistive (GMR) Digital Isolator, Type IL510, Under Extreme Temperatures

    NASA Technical Reports Server (NTRS)

    Patterson, Richard; Hammoud, Ahmad; Panko, Scott

    2010-01-01

    A relatively new type of signal isolation based on Giant Magnetoresistive (GMR) technology was investigated for potential use in harsh temperature environments. Operational characteristics of the 2Mbps single channel, IL510-Series commercial-off-the-shelf (COTS) digital isolator chip was obtained under extreme temperature exposure and thermal cycling in the range of -190 C to +120 C. The isolator was evaluated in terms of its output signal delivery and stability, output rise (t(sub r)) and fall times (t(sub f)), and propagation delays at 50% level between input and output during low to high (t(sub PLH)) and high to low (t(sub PHL)) transitions. The device performed very well throughout the entire test temperature range as no significant changes occurred either in its function or in its output signal timing characteristics. The limited thermal cycling, which comprised of 12 cycles between -190 C and +120 C, also had no influence on its performance. In addition, the device packaging underwent no structural damage due to the extreme temperature exposure. These preliminary results indicate that this semiconductor chip has the potential for use in a temperature range that extends beyond its specified regime. Additional and more comprehensive testing, however, is required to establish its operation and reliability and to determine its suitability for long-term use in space exploration missions.

  4. The Lifetime Estimate for ACSR Single-Stage Splice Connector Operating at Higher Temperatures

    SciTech Connect

    Wang, Jy-An John; Graziano, Joe; Chan, John

    2011-01-01

    This paper is the continuation of Part I effort to develop a protocol of integrating analytical and experimental approaches to evaluate the integrity of a full tension single-stage splice connector (SSC) assembly during service at high operating temperature.1The Part II efforts are mainly focused on the thermal mechanical testing, thermal-cycling simulation and its impact on the effective lifetime of the SSC system. The investigation indicates that thermal cycling temperature and frequency, conductor cable tension loading, and the compressive residual stress field within a SSC system have significant impact on the SSC integrity and the associated effective lifetime.

  5. Frequency characteristics of an inherently stable Nd:YAG laser operated at liquid helium temperature

    SciTech Connect

    Scholz, Matthias; Kovalchuk, Evgeny; Peters, Achim

    2009-07-10

    We report on frequency measurements of a free-running Nd:YAG laser operating at temperatures down to 6.5 K using a femtosecond laser frequency comb. Due to lower thermal expansion and thermo-optic effects as well as reduced electron-phonon interactions in Nd:YAG at cryogenic temperatures, a laser frequency stability on the order of 10{sup -11} at {tau} < or = 30s has been achieved. Within a one-week measurement period, absolute frequency deviations were lower than 1.85 MHz. This is up to a 100-fold improvement of frequency stability compared to any existing free-running solid-state laser.

  6. Operational and theoretical temperature considerations in a Penning surface plasma source

    NASA Astrophysics Data System (ADS)

    Faircloth, D. C.; Lawrie, S. R.; Pereira Da Costa, H.; Dudnikov, V.

    2015-04-01

    A fully detailed 3D thermal model of the ISIS Penning surface plasma source is developed in ANSYS. The proportion of discharge power applied to the anode and cathode is varied until the simulation matches the operational temperature observations. The range of possible thermal contact resistances are modelled, which gives an estimation that between 67% and 85% of the discharge power goes to the cathode. Transient models show the electrode surface temperature rise during the discharge pulse for a range of duty cycles. The implications of these measurements are discussed and a mechanism for governing cesium coverage proposed. The requirements for the design of a high current long pulse source are stated.

  7. Method for producing ceramic composition having low friction coefficient at high operating temperatures

    DOEpatents

    Lankford, Jr., James

    1988-01-01

    A method for producing a stable ceramic composition having a surface with a low friction coefficient and high wear resistance at high operating temperatures. A first deposition of a thin film of a metal ion is made upon the surface of the ceramic composition and then a first ion implantation of at least a portion of the metal ion is made into the near surface region of the composition. The implantation mixes the metal ion and the ceramic composition to form a near surface composite. The near surface composite is then oxidized sufficiently at high oxidizing temperatures to form an oxide gradient layer in the surface of the ceramic composition.

  8. Operational and theoretical temperature considerations in a Penning surface plasma source

    SciTech Connect

    Faircloth, D. C. Lawrie, S. R.; Pereira Da Costa, H.; Dudnikov, V.

    2015-04-08

    A fully detailed 3D thermal model of the ISIS Penning surface plasma source is developed in ANSYS. The proportion of discharge power applied to the anode and cathode is varied until the simulation matches the operational temperature observations. The range of possible thermal contact resistances are modelled, which gives an estimation that between 67% and 85% of the discharge power goes to the cathode. Transient models show the electrode surface temperature rise during the discharge pulse for a range of duty cycles. The implications of these measurements are discussed and a mechanism for governing cesium coverage proposed. The requirements for the design of a high current long pulse source are stated.

  9. Room temperature operational single electron transistor fabricated by focused ion beam deposition

    NASA Astrophysics Data System (ADS)

    Karre, P. Santosh Kumar; Bergstrom, Paul L.; Mallick, Govind; Karna, Shashi P.

    2007-07-01

    We present the fabrication and room temperature operation of single electron transistors using 8nm tungsten islands deposited by focused ion beam deposition technique. The tunnel junctions are fabricated using oxidation of tungsten in peracetic acid. Clear Coulomb oscillations, showing charging and discharging of the nanoislands, are seen at room temperature. The device consists of an array of tunnel junctions; the tunnel resistance of individual tunnel junction of the device is calculated to be as high as 25.13GΩ. The effective capacitance of the array of tunnel junctions was found to be 0.499aF, giving a charging energy of 160.6meV.

  10. An Experimental Study of the Operating Temperature in a Loop Heat Pipe with Two Evaporators and Two Condensers

    NASA Technical Reports Server (NTRS)

    Ku, Jentung; Birur, Gaj; Powers, Edward I. (Technical Monitor)

    2001-01-01

    This paper presents a comprehensive experimental study of the loop operating temperature in a loop heat pipe (LHP) which has two parallel evaporators and two parallel condensers. In a single evaporator LHP, it is well known that the loop operating temperature is a function of the heat load, the sink temperature and the ambient temperature. The objective of the present study emphasizes on the stability of the loop operating temperature and parameters that affects the loop operation. Tests results show that the loop operating temperature is a function of the total system heat load, sink temperature, ambient temperature, and beat load distribution between the two evaporators. Under most conditions, only one compensation chamber (CC) contains two-phase fluid and controls the loop operating temperature, and the other CC is completely filled with liquid. Moreover, as the test condition changes, control of the loop operating temperature often shifted from one CC to another. In spite of complex interactions between various components, the test loop has demonstrated very robust operation even during fast transients.

  11. General information for operation of the high-temperature electromagnetic containerless vacuum induction furnace

    SciTech Connect

    Hahs, C.A.; Fox, R.J.

    1994-06-01

    The High-Temperature Electromagnetic Containerless Vacuum Induction Furnace was developed at Oak Ridge National Laboratory for the National Aeronautics and Space Administration (NASA), Marshall Space Flight Center, Alabama. The high-efficiency radio-frequency system developed for the conceptual design of the Modular Electromagnetic Levitator was created to evaluate this hardware on the KC135 microgravity airplane operated by NASA. Near-future KC135 flights are being planned to levitate, melt, and undercool 5-mm samples of niobium. General information on the operation of this hardware is included.

  12. A simple microfluidic Coriolis effect flowmeter for operation at high pressure and high temperature.

    PubMed

    Harrison, Christopher; Jundt, Jacques

    2016-08-01

    We describe a microfluidic Coriolis effect flowmeter that is simple to assemble, operates at elevated temperature and pressure, and can be operated with a lock-in amplifier. The sensor has a flow rate sensitivity greater than 2° of phase shift per 1 g/min of mass flow and is benchmarked with flow rates ranging from 0.05 to 2.0 g/min. The internal volume is 15 μl and uses off-the-shelf optical components to measure the tube motion. We demonstrate that fluid density can be calculated from the frequency of the resonating element with proper calibration.

  13. A simple microfluidic Coriolis effect flowmeter for operation at high pressure and high temperature

    NASA Astrophysics Data System (ADS)

    Harrison, Christopher; Jundt, Jacques

    2016-08-01

    We describe a microfluidic Coriolis effect flowmeter that is simple to assemble, operates at elevated temperature and pressure, and can be operated with a lock-in amplifier. The sensor has a flow rate sensitivity greater than 2° of phase shift per 1 g/min of mass flow and is benchmarked with flow rates ranging from 0.05 to 2.0 g/min. The internal volume is 15 μl and uses off-the-shelf optical components to measure the tube motion. We demonstrate that fluid density can be calculated from the frequency of the resonating element with proper calibration.

  14. Comparison of Temperature-Index Snowmelt Models for Use within an Operational Water Quality Model.

    PubMed

    Watson, Brett M; Putz, Gordon

    2014-01-01

    The accurate prediction of snowmelt runoff is a critical component of integrated hydrological and water quality models in regions where snowfall constitutes a significant portion of the annual precipitation. In cold regions, the accumulation of a snowpack and the subsequent spring snowmelt generally constitutes a major proportion of the annual water yield. Furthermore, the snowmelt runoff transports significant quantities of sediment and nutrients to receiving streams and strongly influences downstream water quality. Temperature-index models are commonly used in operational hydrological and water quality models to predict snowmelt runoff. Due to their simplicity, computational efficiency, low data requirements, and ability to consistently achieve good results, numerous temperature-index models of varying complexity have been developed in the past few decades. The objective of this study was to determine how temperature-index models of varying complexity would affect the performance of the water quality model SWAT (a modified version of SWAT that was developed for watersheds dominated by boreal forest) for predicting runoff. Temperature-index models used by several operational hydrological models were incorporated into SWAT. Model performance was tested on five watersheds on the Canadian Boreal Plain whose hydrologic response is dominated by snowmelt runoff. The results of this study indicate that simpler temperature-index models can perform as well as more complex temperature-index models for predicting runoff from the study watersheds. The outcome of this study has important implications because the incorporation of simpler temperature-index snowmelt models into hydrological and water quality models can lead to a reduction in the number of parameters that need to be optimized without sacrificing predictive accuracy.

  15. The Integrity of ACSR Full Tension Single-Stage Splice Connector at Higher Operation Temperature

    SciTech Connect

    Wang, Jy-An John; Lara-Curzio, Edgar; King Jr, Thomas J

    2008-10-01

    Due to increases in power demand and limited investment in new infrastructure, existing overhead power transmission lines often need to operate at temperatures higher than those used for the original design criteria. This has led to the accelerated aging and degradation of splice connectors. It is manifested by the formation of hot-spots that have been revealed by infrared imaging during inspection. The implications of connector aging is two-fold: (1) significant increases in resistivity of the splice connector (i.e., less efficient transmission of electricity) and (2) significant reductions in the connector clamping strength, which could ultimately result in separation of the power transmission line at the joint. Therefore, the splice connector appears to be the weakest link in electric power transmission lines. This report presents a protocol for integrating analytical and experimental approaches to evaluate the integrity of full tension single-stage splice connector assemblies and the associated effective lifetime at high operating temperature.

  16. High-Performing, Low-Temperature-Operating, Long-Lifetime Aerospace Lubricants

    NASA Technical Reports Server (NTRS)

    Joshi, Prakash

    2015-01-01

    Long-duration space exploration will require spacecraft systems that can operate effectively over several years with minimal or no maintenance. Aerospace lubricants are key components of spacecraft systems. Physical Sciences Inc., has synthesized and characterized novel ionic liquids for use in aerospace lubricants that contribute to decreased viscosity, friction, and wear in aerospace systems. The resulting formulations offer low vapor pressure and outgassing properties and thermal stability up to 250 C. They are effective for use at temperatures as low as -70 C and provide long-term operational stability in aerospace systems. In Phase II, the company scaled several new ionic liquids and evaluated a novel formulation in a NASA testbed. The resulting lubricant compounds will offer lower volatility, decreased corrosion, and better tribological characteristics than standard liquid lubricants, particularly at lower temperatures.

  17. Improved cycling behavior of ZEBRA battery operated at intermediate temperature of 175°C

    SciTech Connect

    Li, Guosheng; Lu, Xiaochuan; Kim, Jin Yong; Lemmon, John P.; Sprenkle, Vincent L.

    2014-03-01

    Operation of sodium-nickel chloride battery at temperatures lower than 200°C reduces cell degradation and improves the cyclability. One of the main technical issues in terms of operating this battery at intermediate temperatures such as 175°C is the poor wettability of molten sodium on β”-alumina solid electrolyte (BASE) causing reduced active area and limited charging . In order to overcome the problem related to poor wettability of Na melt on BASE at 175°C, Pt grid was applied on the anode side of BASE using a screen printing technique. Deeper charging and improved cycling behavior was observed on the cells with metalized BASEs due to extended active area.

  18. High-density magnetoresistive random access memory operating at ultralow voltage at room temperature

    PubMed Central

    Hu, Jia-Mian; Li, Zheng; Chen, Long-Qing; Nan, Ce-Wen

    2011-01-01

    The main bottlenecks limiting the practical applications of current magnetoresistive random access memory (MRAM) technology are its low storage density and high writing energy consumption. Although a number of proposals have been reported for voltage-controlled memory device in recent years, none of them simultaneously satisfy the important device attributes: high storage capacity, low power consumption and room temperature operation. Here we present, using phase-field simulations, a simple and new pathway towards high-performance MRAMs that display significant improvements over existing MRAM technologies or proposed concepts. The proposed nanoscale MRAM device simultaneously exhibits ultrahigh storage capacity of up to 88 Gb inch−2, ultralow power dissipation as low as 0.16 fJ per bit and room temperature high-speed operation below 10 ns. PMID:22109527

  19. Characterization and temperature dependence of PAH emissions from a simulated rubber combustion operation.

    PubMed

    Jacobs, B W; Billings, C E

    1985-10-01

    The operation investigated uses two induction furnaces for removal of rubber from tracked-vehicle treads. A laboratory-scale simulation of the field operation was employed to generate emissions at 399 degrees C (750 degrees F) and 677 degrees C (1250 degrees F), and emission samples were collected using glass fiber filters and Tenax as the sampling media. Sampling and analytical methods were developed and evaluated with 10 representative polynuclear aromatic hydrocarbons (PAH). High-pressure liquid chromatography (HPLC) and gas chromatography/mass spectrometry (GC/MS) were used to characterize emissions. The PAH were profiled as subsets and graphically displayed as micrograms (micrograms) of emissions per kilogram of rubber and as percentages of total emissions. In each subset, relative amounts of PAH were found to be related to combustion temperatures. Identical coal tar pitch volatiles (CTPV) exposures to emissions generated at the two temperatures studied would result in a 178-fold difference in exposure to carcinogenic PAH.

  20. Operation of the Airmodus A11 nano Condensation Nucleus Counter at various inlet pressures and various operation temperatures, and design of a new inlet system

    NASA Astrophysics Data System (ADS)

    Kangasluoma, Juha; Franchin, Alessandro; Duplissy, Jonahtan; Ahonen, Lauri; Korhonen, Frans; Attoui, Michel; Mikkilä, Jyri; Lehtipalo, Katrianne; Vanhanen, Joonas; Kulmala, Markku; Petäjä, Tuukka

    2016-07-01

    Measuring sub-3 nm particles outside of controlled laboratory conditions is a challenging task, as many of the instruments are operated at their limits and are subject to changing ambient conditions. In this study, we advance the current understanding of the operation of the Airmodus A11 nano Condensation Nucleus Counter (nCNC), which consists of an A10 Particle Size Magnifier (PSM) and an A20 Condensation Particle Counter (CPC). The effect of the inlet line pressure on the measured particle concentration was measured, and two separate regions inside the A10, where supersaturation of working fluid can take place, were identified. The possibility of varying the lower cut-off diameter of the nCNC was investigated; by scanning the growth tube temperature, the range of the lower cut-off was extended from 1-2.5 to 1-6 nm. Here we present a new inlet system, which allows automated measurement of the background concentration of homogeneously nucleated droplets, minimizes the diffusion losses in the sampling line and is equipped with an electrostatic filter to remove ions smaller than approximately 4.5 nm. Finally, our view of the guidelines for the optimal use of the Airmodus nCNC is provided.

  1. Performance and durability of PEM fuel cells operated at sub-freezing temperatures

    SciTech Connect

    Mukundan, Rangachary; Davey, John R; Lujan, Roger W; Spendelow, Jacob S

    2008-01-01

    The durability of polymer electrolyte membrane (PEM) fuel cells operated at sub-freezing temperatures has received increasing attention in recent years. The Department of Energy's PEM fuel cell stack technical targets for the year 2010 include unassisted start-up from -40 {sup o}C and startup from -20 {sup o}C ambient in as low as 30 seconds with < 5 MJ energy consumption. Moreover, the sub-freezing operations should not have any impact on acieving other technical targets including 5000 hours durability. The effect of MEA preparation on the performance of single-PEM fuel cells operated at sub-freezing temperatures is presented. The cell performance and durability are dependent on the MEA and are probably influenced by the porosity of the catalyst layers. When a cell is operated isothermally at -10 {sup o}C in constant current mode, the voltage gradually decreases over time and eventually drops to zero. AC impedance analysis indicated that the rate of voltage loss is initially due to an increase in the charge transfer resistance and is gradual. After a period, the rate of decay accelerates rapidly due to mass transport limitations at the catalyst and/or gas diffusion layers. The high frequency resistance also increases over time during the isothermal operation at sub-freezing temperatures and was a function of the initial membrane water content. LANL prepared MEAs showed very little loss in the catalyst surface area with multiple sub-freezing operations, whereas the commercial MEAs exhibited significant loss in cathode surface area with the anode being unaffected. These results indicate that catalyst layer ice formation is influenced strongly by the MEA and is responsible for the long-term degradation of fuel cells operated at sub-freezing temperatures. This ice formation was monitored using neutron radiography and was found to be concentrated near cell edges at the flow field turns. The water distribution also indicated that ice may be forming mainly in the GDLs at

  2. Effect of operating temperature on the HWB model for solar-collector design

    NASA Astrophysics Data System (ADS)

    Huang, H.; Howell, J. R.

    1983-02-01

    The Hottel-Whillier-Bliss (HWB) Model for the thermal efficiency of a flat plate solar collector plots as a straight line in an esa/sub c/ approx. (T/sub f,in/ - T/sub a/)/g/sub s/ coordinate system under the following assumptions: (1) the effect of the thermal capacity in the collector is negligible; (2) F/sub R/, U/sub L/ are constant in the range of operating temperature. These assumptions simplify the model and make it convenient to use. Because of the intermittance of insulation and the variation of ambient temperature and wind speed, the thermal capacity of the collector may affect the transient efficiency of the collector. In addition, the values of F/sub R/ and U/sub L/ are actually not constant and cause deviation of the efficiency curve from a straight line. The concern is with the deviation of the confidence level for a specific operating range. The effect of operating temperature of the values of F/sub R/ and U/sub L/ is discussed.

  3. Extreme Temperature Operation of a 10 MHz Silicon Oscillator Type STCL1100

    NASA Technical Reports Server (NTRS)

    Patterson, Richard L.; Hammoud, Ahmad

    2008-01-01

    The performance of STMicroelectronics 10 MHz silicon oscillator was evaluated under exposure to extreme temperatures. The oscillator was characterized in terms of its output frequency stability, output signal rise and fall times, duty cycle, and supply current. The effects of thermal cycling and re-start capability at extreme low and high temperatures were also investigated. The silicon oscillator chip operated well with good stability in its output frequency over the temperature region of -50 C to +130 C, a range that by far exceeded its recommended specified boundaries of -20 C to +85 C. In addition, this chip, which is a low-cost oscillator designed for use in applications where great accuracy is not required, continued to function at cryogenic temperatures as low as - 195 C but at the expense of drop in its output frequency. The STCL1100 silicon oscillator was also able to re-start at both -195 C and +130 C, and it exhibited no change in performance due to the thermal cycling. In addition, no physical damage was observed in the packaging material due to extreme temperature exposure and thermal cycling. Therefore, it can be concluded that this device could potentially be used in space exploration missions under extreme temperature conditions in microprocessor and other applications where tight clock accuracy is not critical. In addition to the aforementioned screening evaluation, additional testing, however, is required to fully establish the reliability of these devices and to determine their suitability for long-term use.

  4. Dynamical modelling of an activated sludge system of a petrochemical plant operating at high temperatures.

    PubMed

    Maqueda, M A M; Martinez, Sergio A; Narváez, D; Rodriguez, Miriam G; Aguilar, Ricardo; Herrero, Victor M

    2006-01-01

    The Mexican petrochemical industry, Morelos S.A. de C.V., is one of the biggest and more important petroleum industries in Mexico and Latin America. It has an activated sludge system to treat its wastewater flow, which is approximately 7,000 m3/d. The wastewater contains volatile organic carbon substances classified as toxics. The old surface aeration system was changed for fine bubble diffusers; however, one major drawback of the new aeration system is that the temperature in the bioreactor has increased due to the compression of the air, which at the compressor exit reaches 85 degrees C. This effect results in the temperature in the bioreactor attaining 32 degrees C during the fall, whereas in the spring and summer, the bioreactor temperature reaches higher values than 40 degrees C. The high temperatures reduce the microorganism activity and cause a higher volatilisation rate of volatile compounds, among other effects, which affect the performance of the biological treatment. This work was performed to obtain a better modelling of the wastewater treatment from the petrochemical industry. The model describes the effect of the temperature on the performance of the biological treatment. The model was obtained from tests that were carried out in laboratory reactors with 14 L capacity, which were operated at different temperatures (from 30 to 45 degrees C), with the same wastewater and conditions as the actual system.

  5. Wide-temperature range operation supercapacitors from nanostructured activated carbon fabric

    NASA Astrophysics Data System (ADS)

    Hung, Kaihsuan; Masarapu, Charan; Ko, Tsehao; Wei, Bingqing

    Electrochemical power sources that offer high energy and power densities and, can also withstand a harsh temperature range have become extremely desirable in applications ranging from civilian portable electronic devices to military weapons. In this report, we demonstrated a wide temperature withstanding supercapacitor which can be operated from 100 °C to -40 °C within a voltage window from -2 V to 2 V. The performance of the supercapacitor coin cells, assembled with nanostructured activated carbon fabric (ACF) as the electrode material and 1 M tetraethylammonium tetrafluoroborate (TEABF 4) in polypropylene carbonate (PC) solution as the electrolyte, was systematically studied within the set temperature window. The ACF supercapacitor yielded ideal rectangular shapes in cyclic voltammograms within 0-100 °C with an average mass capacitance of 90 F g -1 and, 60 F g -1 at -25 °C. The capacitance was still over 20 F g -1 at the extremely low temperature of -40 °C. Another exciting feature of the ACF supercapacitors was that they resumed their room temperature capacitance when cooled from 100 °C and defrosted from -40 °C, demonstrating an excellent repeatability and stability. The charge-discharge behavior of the ACF supercapacitors showed long-cycle stability at extreme temperatures. These high electrochemical performances make this type of supercapacitors very promising in many practical applications.

  6. Enhancement of magnetoelectric operating temperature in compressed Cr2O3 under hydrostatic pressure

    NASA Astrophysics Data System (ADS)

    Kota, Yohei; Yoshimori, Yusuke; Imamura, Hiroshi; Kimura, Tsuyoshi

    2017-01-01

    The effect of hydrostatic pressure on structure and magnetism was investigated by a combined theoretical and experimental study for Cr2O3 showing the linear magnetoelectric effect below the Néel temperature TN ≈ 307 K. Based on first-principles calculations and Monte-Carlo simulations, we predicted that TN linearly increases with increasing applied pressure P with the slope of (1/TN)(dTN/dP) = +1.9 × 10-2 GPa-1. This theoretical prediction was qualitatively verified by our experimental observation about the pressure dependence of TN, which was detected by measurements of dielectric constant through the magnetoelectric coupling [(1/TN)(dTN/dP) = +1.6 × 10-2 GPa-1]. These results provide an effective way to enhance magnetoelectric operating temperature in the rare room-temperature magnetoelectric, Cr2O3.

  7. A novel NO2 gas sensor based on Hall effect operating at room temperature

    NASA Astrophysics Data System (ADS)

    Lin, J. Y.; Xie, W. M.; He, X. L.; Wang, H. C.

    2016-09-01

    Tungsten trioxide nanoparticles were obtained by a simple thermal oxidation approach. The structural and morphological properties of these nanoparticles are investigated using XRD, SEM and TEM. A WO3 thick film was deposited on the four Au electrodes to be a WO3 Hall effect sensor. The sensor was tested between magnetic field in a plastic test chamber. Room-temperature nitrogen dioxide sensing characteristics of Hall effect sensor were studied for various concentration levels of nitrogen dioxide at dry air and humidity conditions. A typical room-temperature response of 3.27 was achieved at 40 ppm of NO2 with a response and recovery times of 36 and 45 s, respectively. NO2 gas sensing mechanism of Hall effect sensor was also studied. The room-temperature operation, with the low deposition cost of the sensor, suggests suitability for developing a low-power cost-effective nitrogen dioxide sensor.

  8. Electrolytes for Low-Temperature Operation of Li-CFx Cells

    NASA Technical Reports Server (NTRS)

    Smart, Marshall C.; Whitacre, Jay F.; Bugga, Ratnakumar V.; Prakash, G. K. Surya; Bhalla, Pooja; Smith, Kiah

    2009-01-01

    A report describes a study of electrolyte compositions selected as candidates for improving the low-temperature performances of primary electrochemical cells that contain lithium anodes and fluorinated carbonaceous (CFx) cathodes. This study complements the developments reported in Additive for Low-Temperature Operation of Li-(CF)n Cells (NPO- 43579) and Li/CFx Cells Optimized for Low-Temperature Operation (NPO- 43585), which appear elsewhere in this issue of NASA Tech Briefs. Similar to lithium-based electrolytes described in several previous NASA Tech Briefs articles, each of these electrolytes consisted of a lithium salt dissolved in a nonaqueous solvent mixture. Each such mixture consisted of two or more of the following ingredients: propylene carbonate (PC); 1,2-dimethoxyethane (DME); trifluoropropylene carbonate; bis(2,2,2-trifluoroethyl) ether; diethyl carbonate; dimethyl carbonate; and ethyl methyl carbonate. The report describes the physical and chemical principles underlying the selection of the compositions (which were not optimized) and presents results of preliminary tests made to determine effects of the compositions upon the low-temperature capabilities of Li-CFx cells, relative to a baseline composition of LiBF4 at a concentration of 1.0 M in a solvent comprising equal volume parts of PC and DME.

  9. Hydrazine Operations at Near-Freezing Temperatures During the Ulysses Extended Mission

    NASA Astrophysics Data System (ADS)

    McGarry, A.; Castro, F.; Hodges, M.

    2004-10-01

    The Ulysses mission was recently extended for the third time to March 2008. This extension will require Ulysses to operate far beyond its intended design lifetime at very low power and thermal margins. As a result, it will enter the coldest part of its orbit, as it returns from aphelion at Jupiter distance, with parts of the Reaction Control System (RCS) pipework containing the hydrazine propellant already at near-freezing temperatures. With limited telemetry, no simulator and only a thermal model optimized for the prime mission case, the operations team faces many challenges to avoid freezing of propellant in the RCS, and the hazardous consequences which would result. This paper gives an overview and operational history of the Ulysses monopropellant pressurized hydrazine RCS, describes techniques for detecting possible indications of hydrazine freezing, and potential contingency strategies should partial freezing occur.

  10. Active Control of the Operating Temperature in a Loop Heat Pipe with Two Evaporators and Two Condensers

    NASA Technical Reports Server (NTRS)

    Ku, Jentung; Birur, Gaj; Powers, Edward I. (Technical Monitor)

    2001-01-01

    The operating temperature of a loop heat pipe (LHP) with multiple evaporators is a function of the total heat load, heat load distribution among evaporators, condenser temperature and ambient temperature. Because of the many variables involved, the operating temperature also showed more hystereses than an LHP with a single evaporator. Tight temperature control can be achieved by controlling its compensation chamber (CC) temperatures at the desired set point. This paper describes a test program on active control of the operating temperature in an LHP with two evaporators and two condensers. Temperature control was achieved by heating one or both CC's. Tests performed included start-up, power cycle, sink temperature cycle, CC temperature cycle, and capillary limit. Test results show that, regardless one or two CC's were heated to the set point temperature, one of CC's was always flooded with liquid. The loop could operate successfully at the desired set point temperature under most conditions, including some fast transients. At low heat loads, however, the CC temperature could suddenly increase above the set point temperature, possibly due to a sudden change of the vapor content inside the evaporator core.

  11. Integrated pressure and temperature sensor with high immunity against external disturbance for flexible endoscope operation

    NASA Astrophysics Data System (ADS)

    Maeda, Yusaku; Maeda, Kohei; Kobara, Hideki; Mori, Hirohito; Takao, Hidekuni

    2017-04-01

    In this study, an integrated pressure and temperature sensor device for a flexible endoscope with long-term stability in in vivo environments was developed and demonstrated. The sensor, which is embedded in the thin wall of the disposable endoscope hood, is intended for use in endoscopic surgery. The device surface is coated with a Cr layer to prevent photoelectronic generation induced by the strong light of the endoscope. The integrated temperature sensor allows compensation for the effect of the temperature drift on a pressure signal. The fabricated device pressure resolution is 0.4 mmHg; the corresponding pressure error is 3.2 mmHg. The packaged device was used in a surgical simulation in an animal experiment. Pressure and temperature monitoring was achieved even in a pH 1 acid solution. The device enables intraluminal pressure and temperature measurements of the stomach, which facilitate the maintenance of internal stomach conditions. The applicability of the sensor was successfully demonstrated in animal experiments.

  12. High temperature operation In1-xAlxSb infrared focal plane

    NASA Astrophysics Data System (ADS)

    Lyu, Yanqiu; Si, Junjie; Cao, Xiancun; Zhang, Liang; Peng, Zhenyu; Ding, Jiaxin; Yao, Guansheng; Zhang, Xiaolei; Reobrazhenskiy, Valeriy

    2016-05-01

    A high temperature operation mid-wavelength 128×128 infrared focal plane arrays (FPA) based on low Al component In1-xAlxSb was presented in this work. InAlSb materials were grown on InSb (100) substrates using MBE technology, which was confirmed by XRD and AFM analyses. We have designed and grown two structures with and without barrier. The pixel of the detector had a conventional PIN structure with a size of 50μmx50μm. The device fabrication process consisted of mesa etching, passivation, metallization and flip-chip hybridization with readout integrated circuit (ROIC), epoxy backfill, lap and polish. Diode resistance, imaging, NETD and operability results are presented for a progression of structures that reduce the diode leakage current as the temperature is raised above 80K. These include addition of a thin region of InAlSb to reduce p-contact leakage current, and construction of the whole device from InAlSb to reduce thermal generation in the active region of the detector. An increase in temperature to 110K, whilst maintaining full 80K performance, is achieved. The I-V curves were measured at different temperature. Quantum efficiency, pixel operability, non-uniformity, and the mean NETD values of the FPAs were measured at 110K. This gives the prospect of significant benefits for the cooling systems, including, for example, use of argon in Joule-Thomson coolers or an increase in the life and/or decrease in the cost, power consumption and cool-down time of Stirling engines by several tens of percent.

  13. Impact of Radiation Hardness and Operating Temperatures of Silicon Carbide Electronics on Space Power System Mass

    NASA Technical Reports Server (NTRS)

    Juhasz, Albert J.; Tew, Roy C.; Schwarze, Gene E.

    1998-01-01

    The effect of silicon carbide (SiC) electronics operating temperatures on Power Management and Distribution (PMAD), or Power Conditioning (PC), subsystem radiator size and mass requirements was evaluated for three power output levels (100 kW(e) , 1 MW(e), and 10 MW(e)) for near term technology ( i.e. 1500 K turbine inlet temperature) Closed Cycle Gas Turbine (CCGT) power systems with a High Temperature Gas Reactor (HTGR) heat source. The study was conducted for assumed PC radiator temperatures ranging from 370 to 845 K and for three scenarios of electrical energy to heat conversion levels which needed to be rejected to space by means of the PC radiator. In addition, during part of the study the radiation hardness of the PC electronics was varied at a fixed separation distance to estimate its effect on the mass of the instrument rated reactor shadow shield. With both the PC radiator and the conical shadow shield representing major components of the overall power system the influence of the above on total power system mass was also determined. As expected, results show that the greatest actual mass savings achieved by the use of SiC electronics occur with high capacity power systems. Moreover, raising the PC radiator temperature above 600 K yields only small additional system mass savings. The effect of increased radiation hardness on total system mass is to reduce system mass by virtue of lowering the shield mass.

  14. Operation results of the first commercial PFBC plant with high temperature ceramic filters

    SciTech Connect

    Kaneko, S.; Suga, N.

    1998-07-01

    Trial operation is now successfully underway at Tomato-Atsuma Unit No. 3 of Hokkaido Electric Power Co. (HEPCO) in Japan. This newly built 85 MWe unit is an innovative PFBC plant, which is the first commercial PFBC in Japan, and equipped with full capacity ceramic filters operated at 850 C. The high temperature ceramic filter effectively removes dusts in the hot gas and the dust loading at gas turbine inlet is much less than that of two-stage cyclones, minimizing the cost and time of gas turbine maintenance. The PFBC plant is composed of a pressurized fluidized-bed boiler, cyclones, ceramic filters, a gas turbine, a steam turbine, etc. and all of the equipment were manufactured and supplied by Mitsubishi Heavy Industries, Ltd. (MHI). Joint R and D program between HEPCO and MHI started 7 years ago, based on their own private funding and without any financial supports from public sectors, studying the optimum design of the first commercial PFBC aiming at environmental and economical advantages. And now fruitful results have been achieved. The commercial operation will start in March 1998 or earlier. Several troubles had been experienced during initial trial operation stage including pressure drop increase in ceramic filters. All these problems were solved one by one by the joint efforts of HEPCO and MHO. Load rejection tests, load swing tests, and automatic power control tests were successfully done in the spring of 1997. And tests with various kinds of coals are scheduled before the commercial operation.

  15. Operating experience with the southwire 30-meter high-temperature superconducting power cable

    NASA Astrophysics Data System (ADS)

    Stovall, J. P.; Lue, J. W.; Demko, J. A.; Fisher, P. W.; Gouge, M. J.; Hawsey, R. A.; Armstrong, J. W.; Hughey, R. L.; Lindsay, D. T.; Roden, M. L.; Sinha, U. K.; Tolbert, J. C.

    2002-05-01

    Southwire Company is operating a high-temperature superconducting (HTS) cable system at its corporate headquarters. The 30-m long, 3-phase cable system is powering three Southwire manufacturing plants and is rated at 12.4-kV, 1250-A, 60-Hz. Cooling is provided by a pressurized liquid nitrogen system operating at 70-80 K. The cables were energized on January 5, 2000 for on-line testing and operation and in April 2000 were placed into extended service. As of June 1, 2001, the HTS cables have provided 100% of the customer load for 8000 hours. The cryogenic system has been in continuous operation since November 1999. The HTS cable system has not been the cause of any power outages to the average 20 MW industrial load served by the cable. The cable has been exposed to short-circuit currents caused by load-side faults without damage. Based upon field measurements described herein, the cable critical current-a key performance parameter-remains the same and has not been affected by the hours of real-world operation, further proving the viability of this promising technology.

  16. A New Operational Snow Retrieval Algorithm Applied to Historical AMSR-E Brightness Temperatures

    NASA Technical Reports Server (NTRS)

    Tedesco, Marco; Jeyaratnam, Jeyavinoth

    2016-01-01

    Snow is a key element of the water and energy cycles and the knowledge of spatio-temporal distribution of snow depth and snow water equivalent (SWE) is fundamental for hydrological and climatological applications. SWE and snow depth estimates can be obtained from spaceborne microwave brightness temperatures at global scale and high temporal resolution (daily). In this regard, the data recorded by the Advanced Microwave Scanning Radiometer-Earth Orbiting System (EOS) (AMSR-E) onboard the National Aeronautics and Space Administration's (NASA) AQUA spacecraft have been used to generate operational estimates of SWE and snow depth, complementing estimates generated with other microwave sensors flying on other platforms. In this study, we report the results concerning the development and assessment of a new operational algorithm applied to historical AMSR-E data. The new algorithm here proposed makes use of climatological data, electromagnetic modeling and artificial neural networks for estimating snow depth as well as a spatio-temporal dynamic density scheme to convert snow depth to SWE. The outputs of the new algorithm are compared with those of the current AMSR-E operational algorithm as well as in-situ measurements and other operational snow products, specifically the Canadian Meteorological Center (CMC) and GlobSnow datasets. Our results show that the AMSR-E algorithm here proposed generally performs better than the operational one and addresses some major issues identified in the spatial distribution of snow depth fields associated with the evolution of effective grain size.

  17. Simulating potential structural and operational changes for Detroit Dam on the North Santiam River, Oregon, for downstream temperature management

    USGS Publications Warehouse

    Buccola, Norman L.; Rounds, Stewart A.; Sullivan, Annett B.; Risley, John C.

    2012-01-01

    achievement of downstream temperature goals requires that releases of warm water near the surface of the lake and cold water below the thermocline are both possible with the available dam outlets during spring, summer, and autumn. This constraint can be met to some extent with existing outlets, but only if access to the spillway is extended into autumn by keeping the lake level higher than called for by the current rule curve (the typical target water-surface elevation throughout the year). If new outlets are considered, a variable-elevation outlet such as a sliding gate structure, or a floating outlet in combination with a fixed-elevation outlet at sufficient depth to access cold water, is likely to work well in terms of accessing a range of water temperatures and achieving downstream temperature targets. Furthermore, model results indicate that it is important to release warm water from near the lake surface during midsummer. If not released downstream, the warm water will build up at the top of the lake as a result of solar energy inputs and the thermocline will deepen, potentially causing warm water to reach the depth of deeper fixed-elevation outlets in autumn, particularly when the lake level is drawn down to make room for flood storage. Delaying the drawdown in autumn can help to keep the thermocline above such outlets and preserve access to cold water. Although it is important to generate hydropower at Detroit Dam, minimum power-production requirements limit the ability of dam operators to meet downstream temperature targets with existing outlet structures. The location of the power penstocks below the thermocline in spring and most of summer causes the release of more cool water during summer than is optimal. Reducing the power-production constraint allows the temperature target to be met more frequently, but at the cost of less power generation. Finally, running the Detroit Dam, Big Cliff Dam, and North Santiam and Santiam River models in series allows dam operators

  18. Performance of MEMS Silicon Oscillator, ASFLM1, under Wide Operating Temperature Range

    NASA Technical Reports Server (NTRS)

    Patterson, Richard L.; Hammoud, Ahmad

    2008-01-01

    Over the last few years, MEMS (Micro-Electro-Mechanical Systems) resonator-based oscillators began to be offered as commercial-off-the-shelf (COTS) parts by a few companies [1-2]. These quartz-free, miniature silicon devices could compete with the traditional crystal oscillators in providing the timing (clock function) for many digital and analog electronic circuits. They provide stable output frequency, offer great tolerance to shock and vibration, and are immune to electro-static discharge [1-2]. In addition, they are encapsulated in compact lead-free packages, cover a wide frequency range (1 MHz to 125 MHz), and are specified, depending on the grade, for extended temperature operation from -40 C to +85 C. The small size of the MEMS oscillators along with their reliability and thermal stability make them candidates for use in space exploration missions. Limited data, however, exist on the performance and reliability of these devices under operation in applications where extreme temperatures or thermal cycling swings, which are typical of space missions, are encountered. This report presents the results of the work obtained on the evaluation of an ABRACON Corporation MEMS silicon oscillator chip, type ASFLM1, under extreme temperatures.

  19. High Operating Temperature and Low Power Consumption Boron Nitride Nanosheets Based Broadband UV Photodetector.

    PubMed

    Rivera, Manuel; Velázquez, Rafael; Aldalbahi, Ali; Zhou, Andrew F; Feng, Peter

    2017-03-03

    We extend our work on the use of digitally controlled pulsed laser plasma deposition (PLPD) technique to synthesize high quality, 2-dimensional single crystalline boron nitride nanosheets (BNNSs) at a low substrate temperature for applications in high-performance deep UV photodetectors. The obtained sample consists of a large amount of BNNSs partially overlapping one another with random orientations. Each sheet is composed of a few (from 2 to 10) stacked atomic layers exhibiting high transparency due to its highly ordered hBN crystallinity. Deep UV detectors based on the obtained BNNSs were designed, fabricated, and tested. The bias and temperature effects on the photocurrent strength and the signal-to-noise ratio have been carefully characterized and discussed. A significant shift in the cut off wavelength of the BNNSs based photodetectors was observed suggesting a band gap reduction as a result of the BNNSs' collective structure. The newly designed photodetector presented exceptional properties: a high sensitivity to weak intensities of radiation in both UVC and UVB range while remaining visible-blind, and a high signal-to-noise ratio operation even at temperatures as high as 400 °C. In addition, the BNNSs based photodetector exhibited potential for self-powered operation.

  20. High operation temperature mid-wavelength interband cascade infrared photodetectors grown on InAs substrate

    NASA Astrophysics Data System (ADS)

    Zhou, Yi; Chen, Jianxin; Xu, Zhicheng; He, Li

    2016-05-01

    In recent years, interband cascade detectors (ICIP) based on typer-II superlattice have shown great performance potential at high operation temperature. In this paper, we report our studies on mid-infrared interband cascade photodetectors first grown on InAs substrate. We examined the photo-generated carriers' transport in ICIP structures by comparing three detectors grown on InAs substrate. The 2-stages ICIP device has demonstrated a high quantum efficiency around 20% at room temperature. The dark current density of the 2-stages ICIP device at -0.05V is as low as 1 nA at 80K, 1 mA at 150K, which is comparable to the state of art PIN superlattice photodetectors with similar cutoff wavelength. The Johnson-noise limited D* reaches 1.64×1014cm.Hz1/2/W at 3.65 μm and 80K, and 4.1×1010cm.Hz1/2/W at 3.8 μm and 200K. The 300 K background limited infrared performance (BLIP) operation temperature is estimated to be over 140 K.

  1. High Operating Temperature and Low Power Consumption Boron Nitride Nanosheets Based Broadband UV Photodetector

    PubMed Central

    Rivera, Manuel; Velázquez, Rafael; Aldalbahi, Ali; Zhou, Andrew F.; Feng, Peter

    2017-01-01

    We extend our work on the use of digitally controlled pulsed laser plasma deposition (PLPD) technique to synthesize high quality, 2-dimensional single crystalline boron nitride nanosheets (BNNSs) at a low substrate temperature for applications in high-performance deep UV photodetectors. The obtained sample consists of a large amount of BNNSs partially overlapping one another with random orientations. Each sheet is composed of a few (from 2 to 10) stacked atomic layers exhibiting high transparency due to its highly ordered hBN crystallinity. Deep UV detectors based on the obtained BNNSs were designed, fabricated, and tested. The bias and temperature effects on the photocurrent strength and the signal-to-noise ratio have been carefully characterized and discussed. A significant shift in the cut off wavelength of the BNNSs based photodetectors was observed suggesting a band gap reduction as a result of the BNNSs’ collective structure. The newly designed photodetector presented exceptional properties: a high sensitivity to weak intensities of radiation in both UVC and UVB range while remaining visible-blind, and a high signal-to-noise ratio operation even at temperatures as high as 400 °C. In addition, the BNNSs based photodetector exhibited potential for self-powered operation. PMID:28256507

  2. High Operating Temperature and Low Power Consumption Boron Nitride Nanosheets Based Broadband UV Photodetector

    NASA Astrophysics Data System (ADS)

    Rivera, Manuel; Velázquez, Rafael; Aldalbahi, Ali; Zhou, Andrew F.; Feng, Peter

    2017-03-01

    We extend our work on the use of digitally controlled pulsed laser plasma deposition (PLPD) technique to synthesize high quality, 2-dimensional single crystalline boron nitride nanosheets (BNNSs) at a low substrate temperature for applications in high-performance deep UV photodetectors. The obtained sample consists of a large amount of BNNSs partially overlapping one another with random orientations. Each sheet is composed of a few (from 2 to 10) stacked atomic layers exhibiting high transparency due to its highly ordered hBN crystallinity. Deep UV detectors based on the obtained BNNSs were designed, fabricated, and tested. The bias and temperature effects on the photocurrent strength and the signal-to-noise ratio have been carefully characterized and discussed. A significant shift in the cut off wavelength of the BNNSs based photodetectors was observed suggesting a band gap reduction as a result of the BNNSs’ collective structure. The newly designed photodetector presented exceptional properties: a high sensitivity to weak intensities of radiation in both UVC and UVB range while remaining visible-blind, and a high signal-to-noise ratio operation even at temperatures as high as 400 °C. In addition, the BNNSs based photodetector exhibited potential for self-powered operation.

  3. Above room temperature continuous wave operation of a broad-area quantum-cascade laser

    NASA Astrophysics Data System (ADS)

    Semtsiv, M. P.; Masselink, W. T.

    2016-11-01

    We describe the design and implementation of a broad-area (w ≈ 30 μm) quantum-cascade laser operating in a continuous wave mode up to heat-sink temperatures beyond +100 °C. The room-temperature emission wavelength is 4.6 μm. The temperature gradient in the active region of such a wide laser stripe is essentially perpendicular to the epitaxial layers and the resulting steady-state active region temperature offset scales approximately with the square of the number of cascades. With only 10 cascades in the active region, the threshold electrical power density in the current quantum-cascade laser in the continuous-wave mode is as low as Vth × Ith = 3.8 V × 0.9 kA/cm2 = 3.4 kW/cm2 at room temperature for 2 mm-long two-side high-reflectivity coated laser stripe. A 4 mm-long one-side high-reflectivity coated laser stripe delivers in continuous-wave mode above 0.6 W at +20 °C and above 1.3 W at -27 °C (cooled with a single-stage Peltier element). A 2 mm-long two-side high-reflectivity coated laser stripe demonstrates continuous-wave lasing up to at least +102 °C (375 K). The thermal conductance, Gth, ranges between 235 W/K cm2 and 140 W/K cm2 for temperatures between -33 °C and +102 °C. This demonstration opens the route for continuous-wave power scaling of quantum-cascade lasers via broad-area laser ridges.

  4. Positive bias temperature instability of SiC-MOSFETs induced by gate-switching operation

    NASA Astrophysics Data System (ADS)

    Murakami, Eiichi; Furuichi, Takahiro; Takeshita, Tatsuya; Oda, Kazuhiro

    2017-04-01

    Despite the advances in SiC-MOSFET technology in recent years, high-temperature stability remains a significant issue. In this work, we examine the positive bias temperature instability of SiC-MOSFETs induced by gate-switching operation (AC-PBTI). The dependence of the threshold voltage shift (ΔV th) on the duty-cycle of gate pulses (1 kHz) is measured, which shows a strong dependence on the gate off-voltage V gs(OFF). When using V gs(OFF) = ‑5 V, ΔV th becomes negligible even in a 90% duty cycle, which is practically informative for power circuit applications. The trap–detrap model for Si is used to explain this marked behavior. Finally, by considering the band bending at V gs(OFF), we propose the interface-state-assisted detrapping mechanism as one possible explanation for this behavior.

  5. Extending the operating temperature, wavelength and frequency response of HgCdTe heterodyne detectors

    NASA Technical Reports Server (NTRS)

    Spears, D. L.

    1980-01-01

    Near ideal optical heterodyne performance was obtained at GHz IF frequencies in the 10 micrometer wavelength region with liquid nitrogen cooled HgCdTe photodiodes. Heterodyne NEP's as low as 2.7 x 10 to the minus 20th power W/Hz at 100MHz, 5.4 x 10 to the minus 20th power W/Hz at 1.5 GHz, and 9.4 x 19 to the minus 20th power W/Hz at 3 GHz were achieved. Various physical phenomena which occur within a photodiode and affect heterodyne operation were examined in order to assess the feasibility of extending the operating temperature, wavelength, and frequency response of these HgCdTe photomixers.

  6. Room-temperature operation of a titanium supersaturated silicon-based infrared photodetector

    NASA Astrophysics Data System (ADS)

    García-Hemme, E.; García-Hernansanz, R.; Olea, J.; Pastor, D.; del Prado, A.; Mártil, I.; González-Díaz, G.

    2014-05-01

    We report room-temperature operation of 1 × 1 cm2 infrared photoconductive photodetectors based on silicon supersaturated with titanium. We have fabricated these Si-based infrared photodetectors devices by means of ion implantation followed by a pulsed laser melting process. A high sub-band gap responsivity of 34 mV W-1 has been obtained operating at the useful telecommunication applications wavelength of 1.55 μm (0.8 eV). The sub-band gap responsivity shows a cut-off frequency as high as 1.9 kHz. These Si-based devices exhibit a non-previous reported specific detectivity of 1.7 × 104 cm Hz1/2 W-1 at 660 Hz, under a 1.55 μm wavelength light. This work shows the potential of Ti supersaturated Si as a fully CMOS-compatible material for the infrared photodetection technology.

  7. Rolling contact fatigue behavior of heat resistant bearing steels at high operational temperatures

    SciTech Connect

    Boehmer, H.J.; Hirsch, T.; Streit, E.

    1998-12-31

    An approach was made to estimate the endurance limit in rolling contact fatigue in dependence of the operational conditions for the bearing steels M50 (AMS 6491), M50 NiL (AMS 6278) and the nitrogen-alloyed Cronidur 30 (AMS 5898) by investigating the changes in the residual stress profiles after 5 million cycles of overrolling. Real main shaft bearings with a pitch diameter of 168 mm have been tested. To simulate the heat generated in the turbine engines even under boundary operational conditions oil inlet temperatures between 80 and 210 C have been applied, the rotational speed has been varied between 2,500 and 14,000 r/min and the interference fit has been changed to produce different hoop stress levels.

  8. Operation results of the first commercial PFBC plant with high temperature ceramic filters

    SciTech Connect

    Suga, Nobuyuki; Ishioka, Hidekazu; Ohnishi, Takashi; Kaneko, Shozo; Kinoshita, Masaaki; Hyakutake, Yoshinori

    1998-07-01

    A variety of tests were finished in Unit No. 3 of Tomatoh-Atsuma Power Station, the first commercial PFBC combined cycle unit for utility power generation in Japan, proving the superiority in environmental performance and stable operability. In December, 1997 efficiency test was carried out and commercial operation will start in March 9, 1998. The success in high temperature ceramic filters, will contribute to the establishment of advanced clean coal technologies. Reflecting the results obtained in this first commercial PFBC unit, MHI is finalizing the design of larger size PFBC unit. And along with the development of IGCC, MHI is now developing an advanced PFBC POSEIDON aiming at even better efficiency and environmental performance.

  9. A room-temperature semiconductor spaser operating near 1.5 μm.

    PubMed

    Flynn, R A; Kim, C S; Vurgaftman, I; Kim, M; Meyer, J R; Mäkinen, A J; Bussmann, K; Cheng, L; Choa, F-S; Long, J P

    2011-04-25

    Room temperature spasing of surface plasmon polaritons at 1.46 μm wavelength has been demonstrated by sandwiching a gold-film plasmonic waveguide between optically pumped InGaAs quantum-well gain media. The spaser exhibits gain narrowing, the expected transverse-magnetic polarization, and mirror feedback provided by cleaved facets in a 1-mm long cavity fabricated with a flip-chip approach. The 1.06-μm pump-threshold of ~60 kW/cm2 is in good agreement with calculations. The architecture is readily adaptable to all-electrical operation on an integrated microchip.

  10. A high-temperature gas-and-steam turbine plant operating on combined fuel

    NASA Astrophysics Data System (ADS)

    Klimenko, A. V.; Milman, O. O.; Shifrin, B. A.

    2015-11-01

    A high-temperature gas-steam turbine plant (GSTP) for ultrasupercritical steam conditions is proposed based on an analysis of prospects for the development of power engineering around the world and in Russia up to 2040. The performance indicators of a GSTP using steam from a coal-fired boiler with a temperature of 560-620°C with its superheating to 1000-1500°C by firing natural gas with oxygen in a mixingtype steam superheater are analyzed. The thermal process circuit and design of a GSTP for a capacity of 25 MW with the high- and intermediate-pressure high-temperature parts with the total efficiency equal to 51.7% and the natural gas utilization efficiency equal to 64-68% are developed. The principles of designing and the design arrangement of a 300 MW GSTP are developed. The effect of economic parameters (the level and ratio of prices for solid fuel and gas, and capital investments) on the net cost of electric energy is determined. The net cost of electric energy produced by the GSTP is lower than that produced by modern combined-cycle power plants in a wide variation range of these parameters. The components of a high-temperature GSTP the development of which determines the main features of such installations are pointed out: a chamber for combusting natural gas and oxygen in a mixture with steam, a vacuum device for condensing steam with a high content of nondensables, and a control system. The possibility of using domestically available gas turbine technologies for developing the GSTP's intermediate-pressure high-temperature part is pointed out. In regard of its environmental characteristics, the GSTP is more advantageous as compared with modern condensing power plants: it allows a flow of concentrated carbon dioxide to be obtained at its outlet, which can be reclaimed; in addition, this plant requires half as much consumption of fresh water.

  11. Assessment of Operation of EMK21 MEMS Silicon Oscillator Over Wide Temperature Range

    NASA Technical Reports Server (NTRS)

    Patterson, Richard L.; Hammoud, Ahmad

    2009-01-01

    Electronic control systems, data-acquisition instrumentation, and microprocessors require accurate timing signals for proper operation. Traditionally, ceramic resonators and crystal oscillators provided this clock function for the majority of these systems. Over the last few years, MEMS (Micro-Electro-Mechanical Systems) resonator-based oscillators began to surface as commercial-off-the-shelf (COTS) parts by a few companies. These quartz-free, miniature silicon devices could easily replace the traditional crystal oscillators in providing the timing/clock function for many digital and analog circuits. They are reported to provide stable output frequency, offer great tolerance to shock and vibration, and are immune to electro-static discharge [ 1-2]. In addition, they are encapsulated in compact lead-free packages and cover a wide frequency range (1 MHz to 125 MHz). The small size of the MEMS oscillators along with their thermal stability make them ideal candidates for use in space exploration missions. Limited data, however, exist on the performance and reliability of these devices under operation in applications where extreme temperatures or thermal cycling swings, which are typical of space missions, are encountered. This report presents the results of the work obtained on the evaluation of an Ecliptek Corporation MEMS silicon oscillator chip under extreme temperatures.

  12. Low temperature operated NiO-SnO2 heterostructured SO2 gas sensor

    NASA Astrophysics Data System (ADS)

    Tyagi, Punit; Sharma, Anjali; Tomar, Monika; Gupta, Vinay

    2016-04-01

    Sulfur dioxide (SO2) is among the most toxic gas released by the industries which is extremely dangerous for human health. In the present communication, an attempt has been made for the detection of SO2 gas (500 ppm) with the help of SnO2 thin film based gas sensor. A low sensing response of 1.3 is obtained for sputtered SnO2 thin films based sensors at a high operating temperature of 220 °C. To improve the sensing response, different heterostructured sensors are developed by incorporating other metal oxide thin films (PdO, MgO, NiO, V2O5) over SnO2 thin film surface. Sensing response studies of different sensors towards SO2 gas (500 ppm) are presented in the present report. Among all the prepared sensors NiO-SnO2 hetero-structure sensor is showing highest sensing response (˜8) at a comparatively lower operating temperature (140 °C). Possible sensing mechanism for NiO-SnO2 heterostructured sensor has also been discussed in the present report.

  13. Interface stability of electrode/Bi-containing relaxor ferroelectric oxide for high-temperature operational capacitor

    NASA Astrophysics Data System (ADS)

    Nagata, Takahiro; Kumaragurubaran, Somu; Tsunekawa, Yoshifumi; Yamashita, Yoshiyuki; Ueda, Shigenori; Takahashi, Kenichiro; Ri, Sung-Gi; Suzuki, Setsu; Oh, Seungjun; Chikyow, Toyohiro

    2016-06-01

    The interface stability between electrodes (Pt, TaC, TiC, and RuO2) and a Bi-containing relaxor ferroelectric oxide, BaTiO3-Bi(Mg2/3Nb1/3)O3 (BT-BMN), applied to a high-temperature operational capacitor was investigated by hard X-ray photoelectron spectroscopy. All the electrodes showed electron filling at the Fermi level after annealing at 400 °C. However, Pt and TaC indicated electrical property degradations due to the thick intermediate layer formation and defect formation of the BT-BMN layer relating to the Bi diffusion into the electrodes. In contrast, TiC inhibited the Bi diffusion and did not show any change in the band alignment after annealing. Furthermore, RuO2 eliminated the defect formation in BT-BMN and showed no change in the band alignment although the Bi diffusion was also observed. These results suggest that the TiC/RuO2/BT-BMN stack structure is a potential candidate for the high-temperature operational capacitor.

  14. High-temperature passive direct methanol fuel cells operating with concentrated fuels

    NASA Astrophysics Data System (ADS)

    Zhao, Xuxin; Yuan, Wenxiang; Wu, Qixing; Sun, Hongyuan; Luo, Zhongkuan; Fu, Huide

    2015-01-01

    Conventionally, passive direct methanol fuel cells (DMFC) are fed with diluted methanol solutions and can hardly be operated at elevated temperatures (>120 °C) because the ionic conductivity of Nafion-type proton exchange membranes depends strongly on water content. Such a system design would limit its energy density and power density in mobile applications. In this communication, a passive vapor feed DMFC capable of operating with concentrated fuels at high temperatures is reported. The passive DMFC proposed in this work consists of a fuel reservoir, a perforated silicone sheet, a vapor chamber, two current collectors and a membrane electrode assembly (MEA) based on a phosphoric acid doped polybenzimidazole (PBI) membrane. The experimental results reveal that the methanol crossover through a PBI membrane is substantially low when compared with the Nafion membranes and the PBI-based passive DMFC can yield a peak power density of 37.2 mW cm-2 and 22.1 mW cm-2 at 180 °C when 16 M methanol solutions and neat methanol are used respectively. In addition, the 132 h discharge test indicates that the performance of this new DMFC is quite stable and no obvious performance degradation is observed after activation, showing its promising applications in portable power sources.

  15. Modelling and operation of sub-miniature constant temperature hot-wire anemometry

    NASA Astrophysics Data System (ADS)

    Samie, M.; Watmuff, J. H.; Van Buren, T.; Hutchins, N.; Marusic, I.; Hultmark, M.; Smits, A. J.

    2016-12-01

    High-Reynolds number flows are very common in technological applications and in nature, and hot-wire anemometry is the preferred method for measuring the time-series of fluctuating velocity in such flows. However, measurement of very high-Reynolds number flows requires hot-wires with higher temporal and spatial resolution than is available with conventional probes. Much effort has therefore been devoted to decreasing the size of the hot-wire probes and this has led to associated challenges with operation. It is this latter operation problem which is the focus of this paper. To this end, an existing theoretical model of constant-temperature hot-wire anemometers (Perry 1982 Hot-Wire Anemometry (New York: Oxford University Press), Watmuff 1995 Exp. Therm. Fluid Sci. 11 117-34) is applied, and its accuracy is tested for the first time by comparison to measurements using an in-house constant temperature anemometer (CTA) for both conventional 5~μ m-diameter wires and sub-miniature hot-wires. With the aid of this model, we propose modifications to the CTA design and demonstrate successful operation of the CTA with the Princeton nano-scale thermal anemometry probe (NSTAP) (Bailey et al 2010 J. Fluid Mech. 663 160-79). It is also shown that the transfer function obtained from the model can be utilized to estimate the true frequency response and cut-off frequency of a hot-wire-CTA system to the velocity fluctuations, which is essential in accurate measurements of energy spectrum and higher order statistics of turbulent flows.

  16. 46 CFR 54.10-5 - Maximum allowable working pressure (reproduces UG-98).

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... ENGINEERING PRESSURE VESSELS Inspection, Reports, and Stamping § 54.10-5 Maximum allowable working pressure...) that are likely to occur, or the designated coincident operating temperature, excluding any...

  17. High-temperature operation of 640 nm wavelength high-power laser diode arrays

    NASA Astrophysics Data System (ADS)

    Imanishi, Daisuke

    2017-03-01

    We realized the fabrication of a red semiconductor laser array with high optical power and reliability using an AlGaInP-based compound semiconductor. To obtain a high optical output, the semiconductor laser requires high-quality quantum wells. In this work, we improved quantum well layer abruptness by applying high-temperature growth condition to quantum wells. We obtained a very high optical power of 20.1 W with a wavelength of 644 nm under this growth condition using magnesium as a dopant for a p-type layer. As a results, we achieved a high characteristic temperature of 68 K and a high electrical-to-optical (E–O) conversion efficiency 37% at 15 W optical output. When the laser lifetime at a temperature of 35 °C and an optical output power of 6.6 W for operation is defined as the time when the output power decreases to 50%, which is usually used for defining the lifetime of ultra high-pressure (UHP) lamps in projection display, we can estimate the lifetime of this laser to be longer than 10000 h or more.

  18. Binary and ternary Po-containing molecules relevant for LBE cooled reactors at operating temperature

    NASA Astrophysics Data System (ADS)

    Van Yperen-De Deyne, Andy; Rijpstra, Kim; Waroquier, Michel; Van Speybroeck, Veronique; Cottenier, Stefaan

    2015-03-01

    Quantum-chemical calculations at several levels of theory were used to assess the stability at different temperatures of a set of 13 binary and ternary Po-containing molecules that could possibly be formed in an environment with lead, bismuth, oxygen and water. The conclusions are that especially PoPb, PbPoO and PoOH and to a lesser extent Po2 and PoO are stable. These small molecules are therefore likely to be found near the Lead-Bismuth eutectic (LBE) coolant at operational temperatures in a heavy liquid metal cooled fission reactor. In contrast, Po3 and PoBi are unlikely to be present under the assumed conditions. Several stability criteria, such as the dissociation into free atoms or into molecular fragments at realistic Po-concentrations or in the thermodynamic limit are discussed at different temperatures. The results obtained with a medium level of theory (Density Functional Theory, PBE0 with relativistic effective core potentials) show good qualitative correspondence with calculations performed at a much higher level of theory (Multi Reference Configuration Interaction, with spin-orbit coupling and scalar relativistic Hamiltonian).

  19. Effect of operating parameters and reactor structure on moderate temperature dry desulfurization.

    PubMed

    Zhang, Jie; You, Changfu; Qi, Haiying; Hou, Bo; Chen, Changhe; Xu, Xuchang

    2006-07-01

    A moderate temperature dry desulfurization process at 600-800 degrees C was studied in a pilot-scale circulating fluidized bed flue gas desulfurization (CFB-FGD) experimental facility. The desulfurization efficiency was investigated for various operating parameters, such as bed temperature, CO2 concentration, and solids concentration. In addition, structural improvements in key parts of the CFB-FGD system, i.e., the cyclone separator and the distributor, were made to improve the desulfurization efficiency and flow resistance. The experimental results show that the desulfurization efficiency increased rapidly with increasing temperature above 600 degrees C due to enhanced gas diffusion and the shift of the equilibrium for the carbonate reaction. The sorbent sulfated gradually after quick carbonation of the sorbent with a long particle residence time necessary to realize a high desulfurization ratio. A reduced solids concentration in the bed reduced the particle residence time and the desulfurization efficiency. A single-stage cyclone separator produced no improvement in the desulfurization efficiency compared with a two-stage cyclone separator. Compared with a wind cap distributor, a large hole distributor reduced the flow resistance which reduced the desulfurization efficiency due to the reduced bed pressure drop and worsened bed fluidization. The desulfurization efficiency can be improved by increasing the collection efficiency of fine particles to prolong their residence time and by improving the solids concentration distribution to increase the gas-solid contact surface area.

  20. Potassium ion channels operated by receptor stimulation can be activated simply by raising temperature.

    PubMed

    Tamazawa, Y; Matsumoto, M; Kudo, A; Sasaki, K

    1991-01-01

    Application of either dopamine (DA), acetylcholine (ACh), or histamine (HA) to the identified ganglion cells of Aplysia elicits a K(+)-dependent slow hyperpolarization. When temperature of the bathing solution was raised from 22 to 32 degrees C, these cells were also hyperpolarized with a marked increase in K+ conductance. The warm- and transmitter-induced current responses recorded under voltage clamp were not blocked by either 1 mM Ba2+ or 10 mM TEA. Intracellularly injected guanosine 5'-O-(2-thiodiphosphate) (GDP beta S) depressed both warm- and transmitter-induced K+ responses immediately after the injection. Intracellular application of guanosine 5'-O-(3-thiotriphosphate) (GTP gamma S) caused a gradual, irreversible increase in K+ conductance of the plasma membrane and occluded both responses. Transmitter-induced response markedly decreased when the temperature was raised from 22 to 32 degrees C, suggesting that the response to transmitter was occluded during the warm-induced response. These results suggested that the G-protein regulating the receptor-operated K+ channels could be activated simply by raising temperature.

  1. Experimental design, operation, and results of a 4 kW high temperature steam electrolysis experiment

    NASA Astrophysics Data System (ADS)

    Zhang, Xiaoyu; O'Brien, James E.; Tao, Greg; Zhou, Can; Housley, Gregory K.

    2015-11-01

    High temperature steam electrolysis (HTSE) is a promising technology for large-scale hydrogen production. However, research on HTSE performance above the kW level is limited. This paper presents the results of 4 kW HTSE long-term test completed in a multi-kW test facility recently developed at the Idaho National Laboratory (INL). The 4 kW HTSE unit consisted of two solid oxide electrolysis stacks electrically connected in parallel, each of which included 40 electrode-supported planar cells. A current density of 0.41 A cm-2 was used for the long-term operating at a constant current mode, resulting in a theoretical hydrogen production rate about 23 slpm. A demonstration of 830 h stable operation was achieved with a degradation rate of 3.1% per 1000 h. The paper also includes detailed descriptions of the piping layout, steam generation and delivery system, test fixture, heat recuperation system, hot zone, instrumentation, and operating conditions. This successful demonstration of multi-kW scale HTSE unit will help to advance the technology toward near-term commercialization.

  2. 49 CFR 266.11 - Allowable costs.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 4 2010-10-01 2010-10-01 false Allowable costs. 266.11 Section 266.11... TRANSPORTATION ACT § 266.11 Allowable costs. Allowable costs include only the following costs which are properly allocable to the work performed: Planning and program operation costs which are allowed under...

  3. The Integrity of ACSR Full Tension Splice Connector at Higher Operation Temperature

    SciTech Connect

    Wang, Jy-An John; Lara-Curzio, Edgar; King Jr, Thomas J; Graziano, Joe; Chan, John

    2007-01-01

    Due to the increase in power demand and limited investment in new infrastructure, existing overhead power transmission lines often need to operate at temperatures higher than those used for the original design criteria. This has led to the accelerated aging and degradation of splice connectors, which have been manifested by the formation of hot-spots that have been revealed by infrared imaging during inspection. The implications of connector aging is two-fold: (1) significant increase in resistivity of the splice connector (i.e., less efficient transmission of electricity) and (2) significant reduction in the connector clamping strength, which could ultimately result in separation of the power transmission line at the joint. Therefore, the splice connector appears to be the weakest link in the electric power transmission lines. This paper presents a protocol for integrating analytical and experimental approaches to evaluate the integrity of a full tension single-stage splice connector assembly.

  4. The calibration and operation of a constant-temperature crossed-wire probe in supersonic flow

    NASA Technical Reports Server (NTRS)

    Fernando, E. M.; Donovan, J. F.; Smits, A. J.

    1987-01-01

    The calibration and operation of a constant-temperature crossed-wire probe in supersonic flow is considered. Crossed-wire probes offer considerable advantages over single, inclined wires: the kinematic shear stress can be derived from a single point measurement; the rms quantities can be derived from the same measurement, and the instantaneous quantities can be obtained as a continuous function of time. However, using a crossed-wire probe in supersonic flow is subject to the following practical difficulties: the problem of flow interference, where the shock waves from one wire and its supports interfere with the flow over the other wire; the necessity for high frequency response to resolve the spectral content, and the sensitivity of the results to small changes in the calibration constants. In the present contribution, each of these problems is addressed. Practical solutions are suggested, and some encouraging results are presented.

  5. Effect of Operating Temperature on Structure Properties of TICX Nanoparticle Coating Applied by Pacvd

    NASA Astrophysics Data System (ADS)

    Shanaghi, Ali; Sabour Rouhaghdam, Ali Reza; Ahangarani, Shahrokh; Moradi, Hadi; Mohammadi, Ali

    Titanium carbide (TiC) is a widely used hard coating to improve the wear resistance and lifetime of tools because of its outstanding properties such as high melting point, high hardness, corrosion resistance and abrasion resistance. These properties were drastically improved by using nanotechnology. So in this project, TiCx was applied on hot-working die steel (H11) by Plasma CVD (PACVD). The effect of operating temperatures on TiCx structure properties have been studies by typical and advanced analyses methods such as SEM, XRD, FTIR and Raman. The best properties of TiCx nanoparticle, such as nanostructure, mechanical properties and chemical properties, were obtained at 480 °C.

  6. Thermal insulation for high temperature microwave sintering operations and method thereof

    DOEpatents

    Holcombe, C.E.; Dykes, N.L.; Morrow, M.S.

    1995-09-12

    Superior microwave transparent thermal insulations for high temperature microwave sintering operations were prepared. One embodiment of the thermal insulation comprises granules of boron nitride coated with a very thin layer of glassy carbon made by preparing a glassy carbon precursor and blending it with boron nitride powder to form a mixture. The blended mixture is granulated to form a grit which is dried and heated to form the granules of boron nitride coated with a glassy carbon. Alternatively, grains of glassy carbon are coated with boron nitride by blending a mixture of a slurry comprising boron nitride, boric acid binder, and methyl alcohol with glassy carbon grains to form a blended mixture. The blended mixture is dried to form grains of glassy carbon coated with boron nitride. In addition, a physical mixture of boron nitride powder and glassy carbon grains has also been shown to be an excellent thermal insulation material for microwave processing and sintering. 1 fig.

  7. Method of preparing thermal insulation for high temperature microwave sintering operations

    DOEpatents

    Holcombe, C.E.; Dykes, N.L.; Morrow, M.S.

    1996-07-16

    Superior microwave transparent thermal insulations for high temperature microwave sintering operations were prepared. One embodiment of the thermal insulation comprises granules of boron nitride coated with a very thin layer of glassy carbon made by preparing a glassy carbon precursor and blending it with boron nitride powder to form a mixture. The blended mixture is granulated to form a grit which is dried and heated to form the granules of boron nitride coated with a glassy carbon. Alternatively, grains of glassy carbon are coated with boron nitride by blending a mixture of a slurry comprising boron nitride, boric acid binder, and methyl alcohol with glassy carbon grains to form a blended mixture. The blended mixture is dried to form grains of glassy carbon coated with boron nitride. In addition, a physical mixture of boron nitride powder and glassy carbon grains has also been shown to be an excellent thermal insulation material for microwave processing and sintering. 1 fig.

  8. Thermal insulation for high temperature microwave sintering operations and method thereof

    DOEpatents

    Holcombe, Cressie E.; Dykes, Norman L.; Morrow, Marvin S.

    1995-01-01

    Superior microwave transparent thermal insulations for high temperature microwave sintering operations were prepared. One embodiment of the thermal insulation comprises granules of boron nitride coated with a very thin layer of glassy carbon made by preparing a glassy carbon precursor and blending it with boron nitride powder to form a mixture. The blended mixture is granulated to form a grit which is dried and heated to form the granules of boron nitride coated with a glassy carbon. Alternatively, grains of glassy carbon are coated with boron nitride by blending a mixture of a slurry comprising boron nitride, boric acid binder, and methyl alcohol with glassy carbon grains to form a blended mixture. The blended mixture is dried to form grains of glassy carbon coated with boron nitride. In addition, a physical mixture of boron nitride powder and glassy carbon grains has also been shown to be an excellent thermal insulation material for microwave processing and sintering.

  9. Method of preparing thermal insulation for high temperature microwave sintering operations

    DOEpatents

    Holcombe, Cressie E.; Dykes, Norman L.; Morrow, Marvin S.

    1996-01-01

    Superior microwave transparent thermal insulations for high temperature microwave sintering operations were prepared. One embodiment of the thermal insulation comprises granules of boron nitride coated with a very thin layer of glassy carbon made by preparing a glassy carbon precursor and blending it with boron nitride powder to form a mixture. The blended mixture is granulated to form a grit which is dried and heated to form the granules of boron nitride coated with a glassy carbon. Alternatively, grains of glassy carbon are coated with boron nitride by blending a mixture of a slurry comprising boron nitride, boric acid binder, and methyl alcohol with glassy carbon grains to form a blended mixture. The blended mixture is dried to form grains of glassy carbon coated with boron nitride. In addition, a physical mixture of boron nitride powder and glassy carbon grains has also been shown to be an excellent thermal insulation material for microwave processing and sintering.

  10. A room temperature operating cryogenic cell for in vivo monitoring of dry snow metamorphism by X-ray microtomography

    NASA Astrophysics Data System (ADS)

    Calonne, N.; Flin, F.; Lesaffre, B.; Dufour, A.; Roulle, J.; Puglièse, P.; Philip, A.; Lahoucine, F.; Rolland du Roscoat, S.; Geindreau, C.

    2013-12-01

    Three-dimensional (3D) images of snow offer the possibility of studying snow metamorphism at the grain scale by analysing the time evolution of its complex microstructure. Such images are also particularly useful for providing physical effective properties of snow arising in macroscopic models. In the last 15 years, several experiments have been developed in order to get 3D images of snow by X-ray microtomography. Up to now, two different approaches have been used: a static and an in vivo approach. The static method consists in imaging a snow sample whose structural evolution has been stopped by impregnation and/or very cold temperature conditions. The sample is placed in a cryogenic cell that can operate at the ambient temperature of the tomograph room (e.g. Brzoska et al., 1999, Coléou et al., 2001). The in vivo technique uses a non impregnated sample which continues to undergo structural evolutions and is put in a cell that controls the temperature conditions at the boundaries of the sample. This kind of cell requires a cold environnement and the whole tomographic acquisition process takes place in a cold room (e.g. Schneebeli and Sokratov, 2004, Pinzer and Schneebeli, 2009). The 2nd approach has the major advantage to provide the time evolution of the microstructure of a same snow sample but requires a dedicated cold-room tomographic scanner, whereas the static method can be used with any tomographic scanner operating at ambient conditions. We developed a new in vivo cryogenic cell which benefits from the advantages of each of the above methods: it (1) allows to follow the evolution of the same sample with time and (2) is usable with a wide panel of tomographic scanners provided with large cabin sizes, which has many advantages in terms of speed, resolution, and availability of new technologies. The thermal insulation between the snow sample and the outside is ensured by a double wall vacuum system of thermal conductivity of about 0.0015 Wm-1K-1. An air

  11. 46 CFR 54.25-15 - Low temperature operation-high alloy steels (modifies UHA-23(b) and UHA-51).

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 2 2013-10-01 2013-10-01 false Low temperature operation-high alloy steels (modifies... (CONTINUED) MARINE ENGINEERING PRESSURE VESSELS Construction With Carbon, Alloy, and Heat Treated Steels § 54.25-15 Low temperature operation—high alloy steels (modifies UHA-23(b) and UHA-51). (a)...

  12. 46 CFR 54.25-20 - Low temperature operation-ferritic steels with properties enhanced by heat treatment (modifies...

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 2 2013-10-01 2013-10-01 false Low temperature operation-ferritic steels with... VESSELS Construction With Carbon, Alloy, and Heat Treated Steels § 54.25-20 Low temperature operation—ferritic steels with properties enhanced by heat treatment (modifies UHT-5(c), UHT-6, UHT-23, and...

  13. 46 CFR 54.25-15 - Low temperature operation-high alloy steels (modifies UHA-23(b) and UHA-51).

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 2 2011-10-01 2011-10-01 false Low temperature operation-high alloy steels (modifies... (CONTINUED) MARINE ENGINEERING PRESSURE VESSELS Construction With Carbon, Alloy, and Heat Treated Steels § 54.25-15 Low temperature operation—high alloy steels (modifies UHA-23(b) and UHA-51). (a)...

  14. 46 CFR 54.25-15 - Low temperature operation-high alloy steels (modifies UHA-23(b) and UHA-51).

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 2 2014-10-01 2014-10-01 false Low temperature operation-high alloy steels (modifies... (CONTINUED) MARINE ENGINEERING PRESSURE VESSELS Construction With Carbon, Alloy, and Heat Treated Steels § 54.25-15 Low temperature operation—high alloy steels (modifies UHA-23(b) and UHA-51). (a)...

  15. 46 CFR 54.25-20 - Low temperature operation-ferritic steels with properties enhanced by heat treatment (modifies...

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 2 2011-10-01 2011-10-01 false Low temperature operation-ferritic steels with... VESSELS Construction With Carbon, Alloy, and Heat Treated Steels § 54.25-20 Low temperature operation—ferritic steels with properties enhanced by heat treatment (modifies UHT-5(c), UHT-6, UHT-23, and...

  16. 46 CFR 54.25-10 - Low temperature operation-ferritic steels (replaces UCS-65 through UCS-67).

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 2 2011-10-01 2011-10-01 false Low temperature operation-ferritic steels (replaces UCS... (CONTINUED) MARINE ENGINEERING PRESSURE VESSELS Construction With Carbon, Alloy, and Heat Treated Steels § 54.25-10 Low temperature operation—ferritic steels (replaces UCS-65 through UCS-67). (a) Scope. (1)...

  17. 46 CFR 54.25-20 - Low temperature operation-ferritic steels with properties enhanced by heat treatment (modifies...

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 2 2010-10-01 2010-10-01 false Low temperature operation-ferritic steels with... VESSELS Construction With Carbon, Alloy, and Heat Treated Steels § 54.25-20 Low temperature operation—ferritic steels with properties enhanced by heat treatment (modifies UHT-5(c), UHT-6, UHT-23, and...

  18. 46 CFR 54.25-10 - Low temperature operation-ferritic steels (replaces UCS-65 through UCS-67).

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 2 2010-10-01 2010-10-01 false Low temperature operation-ferritic steels (replaces UCS... (CONTINUED) MARINE ENGINEERING PRESSURE VESSELS Construction With Carbon, Alloy, and Heat Treated Steels § 54.25-10 Low temperature operation—ferritic steels (replaces UCS-65 through UCS-67). (a) Scope. (1)...

  19. 46 CFR 54.25-15 - Low temperature operation-high alloy steels (modifies UHA-23(b) and UHA-51).

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 2 2012-10-01 2012-10-01 false Low temperature operation-high alloy steels (modifies... (CONTINUED) MARINE ENGINEERING PRESSURE VESSELS Construction With Carbon, Alloy, and Heat Treated Steels § 54.25-15 Low temperature operation—high alloy steels (modifies UHA-23(b) and UHA-51). (a)...

  20. 46 CFR 54.25-20 - Low temperature operation-ferritic steels with properties enhanced by heat treatment (modifies...

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 2 2012-10-01 2012-10-01 false Low temperature operation-ferritic steels with... VESSELS Construction With Carbon, Alloy, and Heat Treated Steels § 54.25-20 Low temperature operation—ferritic steels with properties enhanced by heat treatment (modifies UHT-5(c), UHT-6, UHT-23, and...

  1. 46 CFR 54.25-10 - Low temperature operation-ferritic steels (replaces UCS-65 through UCS-67).

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 2 2014-10-01 2014-10-01 false Low temperature operation-ferritic steels (replaces UCS... (CONTINUED) MARINE ENGINEERING PRESSURE VESSELS Construction With Carbon, Alloy, and Heat Treated Steels § 54.25-10 Low temperature operation—ferritic steels (replaces UCS-65 through UCS-67). (a) Scope. (1)...

  2. 46 CFR 54.25-10 - Low temperature operation-ferritic steels (replaces UCS-65 through UCS-67).

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 2 2013-10-01 2013-10-01 false Low temperature operation-ferritic steels (replaces UCS... (CONTINUED) MARINE ENGINEERING PRESSURE VESSELS Construction With Carbon, Alloy, and Heat Treated Steels § 54.25-10 Low temperature operation—ferritic steels (replaces UCS-65 through UCS-67). (a) Scope. (1)...

  3. 46 CFR 54.25-15 - Low temperature operation-high alloy steels (modifies UHA-23(b) and UHA-51).

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 2 2010-10-01 2010-10-01 false Low temperature operation-high alloy steels (modifies... (CONTINUED) MARINE ENGINEERING PRESSURE VESSELS Construction With Carbon, Alloy, and Heat Treated Steels § 54.25-15 Low temperature operation—high alloy steels (modifies UHA-23(b) and UHA-51). (a)...

  4. 46 CFR 54.25-10 - Low temperature operation-ferritic steels (replaces UCS-65 through UCS-67).

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 2 2012-10-01 2012-10-01 false Low temperature operation-ferritic steels (replaces UCS... (CONTINUED) MARINE ENGINEERING PRESSURE VESSELS Construction With Carbon, Alloy, and Heat Treated Steels § 54.25-10 Low temperature operation—ferritic steels (replaces UCS-65 through UCS-67). (a) Scope. (1)...

  5. 46 CFR 54.25-20 - Low temperature operation-ferritic steels with properties enhanced by heat treatment (modifies...

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 2 2014-10-01 2014-10-01 false Low temperature operation-ferritic steels with... VESSELS Construction With Carbon, Alloy, and Heat Treated Steels § 54.25-20 Low temperature operation—ferritic steels with properties enhanced by heat treatment (modifies UHT-5(c), UHT-6, UHT-23, and...

  6. Short-wavelength interband cascade infrared photodetectors operating above room temperature

    DOE PAGES

    Lotfi, Hossein; Li, Lu; Lei, Lin; ...

    2016-01-13

    High temperature operation (250–340 K) of short-wavelength interband cascade infrared photodetectors (ICIPs) with InAs/GaSb/Al0.2In0.8Sb/GaSb superlattice absorbers has been demonstrated with a 50% cutoff wavelength of 2.9 μm at 300 K. Two ICIP structures, one with two and the other with three stages, were designed and grown to explore this multiple-stage architecture. At λ = 2.1 μm, the two- and three-stage ICIPs had Johnson-noise-limited detectivities of 5.1 × 109 and 5.8 ×109 cm Hz1/2/W, respectively, at 300 K. The better device performance of the three-stage ICIP over the two-stage ICIP confirmed the advantage of more stages for this cascade architecture. Furthermore,more » an Arrhenius activation energy of 450 meV is extracted for the bulk resistance-area product, which indicates the dominance of the diffusion current at these high temperatures.« less

  7. Short-wavelength interband cascade infrared photodetectors operating above room temperature

    SciTech Connect

    Lotfi, Hossein; Li, Lu; Lei, Lin; Jiang, Yuchao; Yang, Rui Q.; Klem, John F.; Johnson, Matthew B.

    2016-01-13

    High temperature operation (250–340 K) of short-wavelength interband cascade infrared photodetectors (ICIPs) with InAs/GaSb/Al0.2In0.8Sb/GaSb superlattice absorbers has been demonstrated with a 50% cutoff wavelength of 2.9 μm at 300 K. Two ICIP structures, one with two and the other with three stages, were designed and grown to explore this multiple-stage architecture. At λ = 2.1 μm, the two- and three-stage ICIPs had Johnson-noise-limited detectivities of 5.1 × 109 and 5.8 ×109 cm Hz1/2/W, respectively, at 300 K. The better device performance of the three-stage ICIP over the two-stage ICIP confirmed the advantage of more stages for this cascade architecture. Furthermore, an Arrhenius activation energy of 450 meV is extracted for the bulk resistance-area product, which indicates the dominance of the diffusion current at these high temperatures.

  8. Vital roles of nano silica in synthetic based mud for high temperature drilling operation

    NASA Astrophysics Data System (ADS)

    Yusof, Muhammad Aslam Md; Hanafi, Nor Hazimastura

    2015-07-01

    At high temperature drilling, chemicals degradation occurs which reduce the effectiveness of the drilling fluid. There is a potential that by using nano sized particles which have thermal stability up to 2500°F to be used as a stabilizer to withstand the harsh condition. Therefore, this project aims to identify the performance of synthetic-based mud (SBM) with nano silica for high temperature drilling operation. A conventional SBM performance has been compared with additional percentages of nano silica. 20% and 40% of nano silica out of fluid loss weight has been added into the SBM and analyzed the rheological properties and other drilling fluid properties. The conventional SBM formulation has lost some amount of weighting material or solids in the mud and has been replaced by lighter and smaller size of nanoparticles. It has reduced the rheological properties of the mud but the gelation formed by nano silica material has given higher gel strength. Also, nano silica potentially plugs the porous media, resulted in lower filtration loss measurement and thinner mud cake ranged 20% to 50% respectively.

  9. Feasibility study of SiGHT: a novel ultra low background photosensor for low temperature operation

    NASA Astrophysics Data System (ADS)

    Wang, Y.; Fan, A.; Fiorillo, G.; Galbiati, C.; Guan, M. Y.; Korga, G.; Pantic, E.; Razeto, A.; Renshaw, A.; Rossi, B.; Suvorov, Y.; Wang, H.; Yang, C. G.

    2017-02-01

    Rare event search experiments, such as those searching for dark matter and observations of neutrinoless double beta decay, require ultra low levels of radioactive background for unmistakable identification. In order to reduce the radioactive background of detectors used in these types of event searches, low background photosensors are required, as the physical size of these detectors become increasing larger, and hence the number of such photosensors used also increases rapidly. Considering that most dark matter and neutrinoless double beta decay experiments are turning towards using noble liquids as the target choice, liquid xenon and liquid argon for instance, photosensors that can work well at cryogenic temperatures are required, 165 K and 87 K for liquid xenon and liquid argon, respectively. The Silicon Geiger Hybrid Tube (SiGHT) is a novel photosensor designed specifically for use in ultra low background experiments operating at cryogenic temperatures. It is based on the proven photocathode plus silicon photomultiplier (SiPM) hybrid technology and consists of very few other, but also ultra radio-pure, materials like fused silica and silicon for the SiPM. The introduction of the SiGHT concept, as well as a feasibility study for its production, is reported in this paper.

  10. Monolithically integrated mid-IR interband cascade laser and photodetector operating at room temperature

    NASA Astrophysics Data System (ADS)

    Lotfi, Hossein; Li, Lu; Shazzad Rassel, S. M.; Yang, Rui Q.; Corrége, Cédric J.; Johnson, Matthew B.; Larson, Preston R.; Gupta, James A.

    2016-10-01

    We report on the demonstration of a monolithically integrated mid-IR interband cascade (IC) laser and photodetector operating at room temperature. The base structure for the integrated laser and detector is a six-stage type-I IC laser with GaInAsSb quantum well active regions. The laser/detector pair was defined using focused ion beam milling. The laser section lased in cw mode with an emission wavelength of ˜3.1 μm at 20 °C and top-illuminated photodetectors fabricated from the same wafer had Johnson-noise-limited detectivity of 1.05 × 109 cm Hz1/2/W at this wavelength and temperature. Under the same condition, the detectivity for the edge illumination configuration for the monolithically integrated laser/photodetector pairs is projected to be as high as 1.85 × 1010 cm Hz1/2/W, as supported by experimentally observed high photocurrent and open-circuit voltage. These high performance characteristics for monolithically integrated IC devices show great prospects for on-chip integration of mid-IR photonic devices for miniaturized sensors and on-chip optical communication systems.

  11. Operation and Improvement of Liquid Nitrogen Pumps with Radial High- Temperature Superconductor Bearings

    NASA Astrophysics Data System (ADS)

    Lin, Q. X.; Jiang, D. H.; Deng, Z. G.; Ma, G. T.; Zheng, J.; Wang, W. J.; Shin, D. I.; Gu, X.; Lin, N.; Shao, M. L.

    2015-09-01

    This paper reviews the advantages of replacing the mechanical bearings of low-temperature pumps by radial high- temperature superconductor (HTS) bearings. Radial HTS bearings have the advantage of being non-abrasive, so that the working life is increased significantly. In this article, two types of liquid nitrogen pump with radial HTS bearings are proposed. To reduce heat leakage, one pump uses a permanent magnet (PM) coupling and the other uses a long hollow pipe coupling. Successful stable operation of these two pumps means that radial HTS bearings have the potential to be applied in liquid nitrogen pumps. Test results show that the flow rate is influenced mainly by rotational speed but not by the coupling component. Further designs of the two types of pump for practical applications are described, and their characteristics are analyzed: the pump with a PM coupling has lower heat leakage, whereas the pump with a long hollow pipe coupling can solve the force creep problem of the HTS bearing. The design of the pump with a long hollow pipe coupling is based on the pump that is already in practical use, and therefore has greater feasibility for practical applications. Finally, improvements of the liquid nitrogen pump by improving the structure of the pump and the performance of the radial HTS bearing are discussed.

  12. Design and performance of a rugged standard operative temperature thermometer for avian studies

    USGS Publications Warehouse

    Bakken, G.S.; Boysen, A.F.; Korschgen, C.E.; Kenow, K.P.; Lima, S.L.

    2001-01-01

    The lack of a truly satisfactory sensor which can characterize the thermal environment at the spatial scale experienced by small endotherms has hindered study of their thermoregulatory behavior. We describe a general design for a rugged, easily constructed sensor to measure standard operative temperature, Tes. We present specific designs for adult dark-eyed juncos (Junco hyemalis) and hatchling mallards (Anas platyrhynchos). Sensor response was stable and repeatable (??1.4%) over the course of several months. Over the range of conditions for which validation data were available (variable air temperature and wind with negligible net radiation), sensors predicted the mean net heat production of live animals to within ??0.023W (equivalent to ??1??C at Tes= 15??C). The main limit on accuracy was scatter in the data on metabolism and evaporative water loss in live animals. These sensors are far more rugged and easily constructed than the heated taxidermic mounts previously used to measure Tes. These characteristics facilitate the use of significant numbers of sensors in thermal mapping studies of endotherms. ?? 2001 Elsevier Science Ltd. All rights reserved.

  13. Preliminary operational results of the low temperature solar industrial process heat field tests

    NASA Astrophysics Data System (ADS)

    Kutscher, C. F.; Davenport, R. L.

    1980-06-01

    Six solar industrial process heat field tests have been in operation for a year or more, three are hot water systems and three are hot air systems. All are low temperature projects (process heat at temperatures below 212 F). Performance results gathered by each contractor's data acquisition system are presented and project costs and problems encountered are summarized. Flat plate, evaluated tube, and line focus collectors are all represented with collector array areas ranging from 2500 to 21,000 sq ft. Collector array efficiencies ranged form 12% to 36% with net system efficiencies from 8% to 33%. Low efficiencies are attributable in some cases to high thermal losses and, for the two projects using air collectors, are due in part to high parasitic power consumptions. Problems included industrial effluents on collectors, glazing and absorber surface failures, excessive thermal losses, freezing and overheating, control problems, and data acquisition system failure. With design and data acquisition costs excluded, costs of the projects ranged from $25/sq ft to $87/ sq ft and $499/(MBtu/yr) to $1537/(MBtu/yr).

  14. Effect of operating parameters and reactor structure on moderate temperature dry desulfurization

    SciTech Connect

    Jie Zhang; Changfu You; Haiying Qi; Bo Hou; Changhe Chen; Xuchang Xu

    2006-07-01

    A moderate temperature dry desulfurization process at 600-800 C was studied in a pilot-scale circulating fluidized bed flue gas desulfurization (CFB-FGD) experimental facility. The desulfurization efficiency was investigated for various operating parameters. Structural improvements in key parts of the CFB-FGD system, i.e., the cyclone separator and the distributor, were made to improve the desulfurization efficiency and flow resistance. The experimental results show that the desulfurization efficiency increased rapidly with increasing temperature above 600 C due to enhanced gas diffusion and the shift of the equilibrium for the carbonate reaction. The sorbent sulfated gradually after quick carbonation of the sorbent with a long particle residence time necessary to realize a high desulfurization ratio. A reduced solids concentration in the bed reduced the particle residence time and the desulfurization efficiency. A single-stage cyclone separator produced no improvement in the desulfurization efficiency compared with a two-stage cyclone separator. Compared with a wind cap distributor, a large hole distributor reduced the flow resistance which reduced the desulfurization efficiency due to the reduced bed pressure drop and worsened bed fluidization. The desulfurization efficiency can be improved by increasing the collection efficiency of fine particles to prolong their residence time and by improving the solids concentration distribution to increase the gas-solid contact surface area. 16 refs., 9 figs.

  15. Diagnostics comparing sea surface temperature feedbacks from operational hurricane forecasts to observations

    NASA Astrophysics Data System (ADS)

    Lloyd, Ian D.; Marchok, Timothy; Vecchi, Gabriel A.

    2011-04-01

    This paper examines the ability of recent versions of the Geophysical Fluid Dynamics Laboratory Operational Hurricane Forecast Model (GHM) to reproduce the observed relationship between hurricane intensity and hurricane-induced Sea Surface Temperature (SST) cooling. The analysis was performed by taking a Lagrangian composite of all hurricanes in the North Atlantic from 1998-2009 in observations and 2005-2009 for the GHM. A marked improvement in the intensity-SST relationship for the GHM compared to observations was found between the years 2005 and 2006-2009 due to the introduction of warm-core eddies, a representation of the loop current, and changes to the drag coefficient parameterization for bulk turbulent flux computation. A Conceptual Hurricane Intensity Model illustrates the essential steady-state characteristics of the intensity-SST relationship and is explained by two coupled equations for the atmosphere and ocean. The conceptual model qualitatively matches observations and the 2006-2009 period in the GHM, and presents supporting evidence for the conclusion that weaker upper oceanic thermal stratification in the Gulf of Mexico, caused by the introduction of the loop current and warm core eddies, is crucial to explaining the observed SST-intensity pattern. The diagnostics proposed by the conceptual model offer an independent set of metrics for comparing operational hurricane forecast models to observations.

  16. Computer-Aided Design of Materials for use under High Temperature Operating Condition

    SciTech Connect

    Rajagopal, K. R.; Rao, I. J.

    2010-01-31

    The procedures in place for producing materials in order to optimize their performance with respect to creep characteristics, oxidation resistance, elevation of melting point, thermal and electrical conductivity and other thermal and electrical properties are essentially trial and error experimentation that tend to be tremendously time consuming and expensive. A computational approach has been developed that can replace the trial and error procedures in order that one can efficiently design and engineer materials based on the application in question can lead to enhanced performance of the material, significant decrease in costs and cut down the time necessary to produce such materials. The work has relevance to the design and manufacture of turbine blades operating at high operating temperature, development of armor and missiles heads; corrosion resistant tanks and containers, better conductors of electricity, and the numerous other applications that are envisaged for specially structured nanocrystalline solids. A robust thermodynamic framework is developed within which the computational approach is developed. The procedure takes into account microstructural features such as the dislocation density, lattice mismatch, stacking faults, volume fractions of inclusions, interfacial area, etc. A robust model for single crystal superalloys that takes into account the microstructure of the alloy within the context of a continuum model is developed. Having developed the model, we then implement in a computational scheme using the software ABAQUS/STANDARD. The results of the simulation are compared against experimental data in realistic geometries.

  17. Wide Operating Temperature Range Electrolytes for High Voltage and High Specific Energy Li-Ion Cells

    NASA Technical Reports Server (NTRS)

    Smart, M. C.; Hwang, C.; Krause, F. C.; Soler, J.; West, W. C.; Ratnakumar, B. V.; Amine, K.

    2012-01-01

    A number of electrolyte formulations that have been designed to operate over a wide temperature range have been investigated in conjunction with layered-layered metal oxide cathode materials developed at Argonne. In this study, we have evaluated a number of electrolytes in Li-ion cells consisting of Conoco Phillips A12 graphite anodes and Toda HE5050 Li(1.2)Ni(0.15)Co(0.10)Mn(0.55)O2 cathodes. The electrolytes studied consisted of LiPF6 in carbonate-based electrolytes that contain ester co-solvents with various solid electrolyte interphase (SEI) promoting additives, many of which have been demonstrated to perform well in 4V systems. More specifically, we have investigated the performance of a number of methyl butyrate (MB) containing electrolytes (i.e., LiPF6 in ethylene carbonate (EC) + ethyl methyl carbonate (EMC) + MB (20:20:60 v/v %) that contain various additives, including vinylene carbonate, lithium oxalate, and lithium bis(oxalato)borate (LiBOB). When these systems were evaluated at various rates at low temperatures, the methyl butyrate-based electrolytes resulted in improved rate capability compared to cells with all carbonate-based formulations. It was also ascertained that the slow cathode kinetics govern the generally poor rate capability at low temperature in contrast to traditionally used LiNi(0.80)Co(0.15)Al(0.05)O2-based systems, rather than being influenced strongly by the electrolyte type.

  18. Temperature Effects of Point Sources, Riparian Shading, and Dam Operations on the Willamette River, Oregon

    USGS Publications Warehouse

    Rounds, Stewart A.

    2007-01-01

    Water temperature is an important factor influencing the migration, rearing, and spawning of several important fish species in rivers of the Pacific Northwest. To protect these fish populations and to fulfill its responsibilities under the Federal Clean Water Act, the Oregon Department of Environmental Quality set a water temperature Total Maximum Daily Load (TMDL) in 2006 for the Willamette River and the lower reaches of its largest tributaries in northwestern Oregon. As a result, the thermal discharges of the largest point sources of heat to the Willamette River now are limited at certain times of the year, riparian vegetation has been targeted for restoration, and upstream dams are recognized as important influences on downstream temperatures. Many of the prescribed point-source heat-load allocations are sufficiently restrictive that management agencies may need to expend considerable resources to meet those allocations. Trading heat allocations among point-source dischargers may be a more economical and efficient means of meeting the cumulative point-source temperature limits set by the TMDL. The cumulative nature of these limits, however, precludes simple one-to-one trades of heat from one point source to another; a more detailed spatial analysis is needed. In this investigation, the flow and temperature models that formed the basis of the Willamette temperature TMDL were used to determine a spatially indexed 'heating signature' for each of the modeled point sources, and those signatures then were combined into a user-friendly, spreadsheet-based screening tool. The Willamette River Point-Source Heat-Trading Tool allows the user to increase or decrease the heating signature of each source and thereby evaluate the effects of a wide range of potential point-source heat trades. The predictions of the Trading Tool were verified by running the Willamette flow and temperature models under four different trading scenarios, and the predictions typically were accurate

  19. Effects of Operating Temperature on Droplet Casting of Flexible Polymer/Multi-Walled Carbon Nanotube Composite Gas Sensors

    PubMed Central

    Chiou, Jin-Chern; Wu, Chin-Cheng; Huang, Yu-Chieh; Chang, Shih-Cheng; Lin, Tse-Mei

    2016-01-01

    This study examined the performance of a flexible polymer/multi-walled carbon nanotube (MWCNT) composite sensor array as a function of operating temperature. The response magnitudes of a cost-effective flexible gas sensor array equipped with a heater were measured with respect to five different operating temperatures (room temperature, 40 °C, 50 °C, 60 °C, and 70 °C) via impedance spectrum measurement and sensing response experiments. The selected polymers that were droplet cast to coat a MWCNT conductive layer to form two-layer polymer/MWCNT composite sensing films included ethyl cellulose (EC), polyethylene oxide (PEO), and polyvinylpyrrolidone (PVP). Electrical characterization of impedance, sensing response magnitude, and scanning electron microscope (SEM) morphology of each type of polymer/MWCNT composite film was performed at different operating temperatures. With respect to ethanol, the response magnitude of the sensor decreased with increasing operating temperatures. The results indicated that the higher operating temperature could reduce the response and influence the sensitivity of the polymer/MWCNT gas sensor array. The morphology of polymer/MWCNT composite films revealed that there were changes in the porous film after volatile organic compound (VOC) testing. PMID:28025507

  20. Derivation and evaluation of land surface temperature from the geostationary operational environmental satellite series

    NASA Astrophysics Data System (ADS)

    Fang, Li

    The Geostationary Operational Environmental Satellites (GOES) have been continuously monitoring the earth surface since 1970, providing valuable and intensive data from a very broad range of wavelengths, day and night. The National Oceanic and Atmospheric Administration's (NOAA's) National Environmental Satellite, Data, and Information Service (NESDIS) is currently operating GOES-15 and GOES-13. The design of the GOES series is now heading to the 4 th generation. GOES-R, as a representative of the new generation of the GOES series, is scheduled to be launched in 2015 with higher spatial and temporal resolution images and full-time soundings. These frequent observations provided by GOES Image make them attractive for deriving information on the diurnal land surface temperature (LST) cycle and diurnal temperature range (DTR). These parameters are of great value for research on the Earth's diurnal variability and climate change. Accurate derivation of satellite-based LSTs from thermal infrared data has long been an interesting and challenging research area. To better support the research on climate change, the generation of consistent GOES LST products for both GOES-East and GOES-West from operational dataset as well as historical archive is in great demand. The derivation of GOES LST products and the evaluation of proposed retrieval methods are two major objectives of this study. Literature relevant to satellite-based LST retrieval techniques was reviewed. Specifically, the evolution of two LST algorithm families and LST retrieval methods for geostationary satellites were summarized in this dissertation. Literature relevant to the evaluation of satellite-based LSTs was also reviewed. All the existing methods are a valuable reference to develop the GOES LST product. The primary objective of this dissertation is the development of models for deriving consistent GOES LSTs with high spatial and high temporal coverage. Proper LST retrieval algorithms were studied

  1. High Speed, High Temperature, Fault Tolerant Operation of a Combination Magnetic-Hydrostatic Bearing Rotor Support System for Turbomachinery

    NASA Technical Reports Server (NTRS)

    Jansen, Mark; Montague, Gerald; Provenza, Andrew; Palazzolo, Alan

    2004-01-01

    Closed loop operation of a single, high temperature magnetic radial bearing to 30,000 RPM (2.25 million DN) and 540 C (1000 F) is discussed. Also, high temperature, fault tolerant operation for the three axis system is examined. A novel, hydrostatic backup bearing system was employed to attain high speed, high temperature, lubrication free support of the entire rotor system. The hydrostatic bearings were made of a high lubricity material and acted as journal-type backup bearings. New, high temperature displacement sensors were successfully employed to monitor shaft position throughout the entire temperature range and are described in this paper. Control of the system was accomplished through a stand alone, high speed computer controller and it was used to run both the fault-tolerant PID and active vibration control algorithms.

  2. New approach of gravity wave detection in mesopause temperatures operating an array of airglow spectrometers

    NASA Astrophysics Data System (ADS)

    Wachter, Paul; Schmidt, Carsten; Wüst, Sabine; Bittner, Michael

    2014-05-01

    GRIPS (Ground based Infrared P-branch Spectrometer) airglow measurements allow the derivation of kinetic temperature in the mesopause region averaged over a field of view of some 10km x 10km. In 2011, three identical GRIPS instruments were setup at Oberpfaffenhofen (11.28°E, 48.09°N), Germany, in a way that their fields of view form an equilateral triangle shape in the mesopause with a horizontal dimension of approximately 70km. Using this setup, GRIPS time series cannot only be analyzed with respect to gravity wave periods, but also spatial wave parameters can be derived. Based on the results of the harmonic analysis the horizontal wavelength, phase speed and the direction of propagation were determined for gravity wave events from February to July 2011. We present distinct relationships between periods, amplitudes, phase speeds and wavelengths, which were identified in this dataset. Further data analysis of the derived wave parameters show preferred directions of propagation and suggest seasonal variations of the wave characteristics. The presentation will be concluded by the introduction of a measurement setup relying on one GRIPS instrument which is equipped with a variably adjustable mirror optic. The capability to scan multiple fields of view during nightly measurements will offer longer-term investigations of mesopause gravity waves.

  3. A High-Sensitivity Gas Sensor Toward Methanol Using ZnO Microrods: Effect of Operating Temperature

    NASA Astrophysics Data System (ADS)

    Sinha, M.; Mahapatra, R.; Mondal, B.; Ghosh, R.

    2017-04-01

    In the present work, zinc oxide (ZnO) microrods with the average diameter of 350 nm have been synthesized on fluorine doped tin oxide (FTO) substrate using a hydrothermal reaction process at a low temperature of 90°C. The methanol gas sensing behaviour of as-synthesized ZnO microrods have been studied at different operating temperatures (100-300°C). The gas sensing results show that the ZnO microrods exhibit excellent sensitivity, selectivity, and stability toward methanol gas at 300°C. The as-grown ZnO microrods sensor also shows the good sensitivity for methanol even at a low operating temperature of 100°C. The ultra-high sensitivity of 4.41 × 104% [gas sensitivity, S g = ( I g - I a)/ I a × 100%] and 5.11 × 102% to 100 ppm methanol gas at a temperature of 300°C and 100°C, respectively, has been observed. A fast response time of 200 ms and 270 ms as well as a recovery time of 120 ms and 1330 ms to methanol gas have also been found at an operating temperature of 300°C and 100°C, respectively. The response and recovery time decreases with increasing operation temperature of the sensor.

  4. Variation of ADM1 by using temperature-phased anaerobic digestion (TPAD) operation.

    PubMed

    Lee, Myung-Yeol; Suh, Chang-Won; Ahn, Yong-Tae; Shin, Hang-Sik

    2009-06-01

    The objective of the study was to examine the application of the Anaerobic Digestion Model No. 1 (ADM1) developed by the IWA task group for mathematical modelling of anaerobic process. Lab-scale temperature-phased anaerobic digestion (TPAD) process were operated continuously, and were fed with co-substrate composed of dog food and flour. The model platform implemented in the simulation was a derivative of the ADM1. Sensitivity analysis showed that k(m.process) (maximum specific uptake rate) and K(S.process) (half saturation value) had high sensitivities to model components. Important parameters including maximum uptake rate for propionate utilisers (k(m.pro)) and half saturation constant for acetate utilisers (K(S.ac)) in the thermophilic digester and maximum uptake rate for acetate utilisers (k(m.ac)) in the mesophilic digester were estimated using iterative methods, which optimized the parameters with experimental results. Simulation with estimated parameters showed good agreement with experimental results in the case of methane production, uptake of acetate, soluble chemical oxygen demand (SCOD) and total chemical oxygen demand (TCOD). Under these conditions, the model predicted reasonably well the dynamic behavior of the TPAD process for verifying the model.

  5. OSI-SAF operational NPP/VIIRS sea surface temperature chain

    NASA Astrophysics Data System (ADS)

    Le Borgne, Pierre; Legendre, Gérard; Marsouin, Anne; Péré, Sonia; Roquet, Hervé

    2013-06-01

    Data of the Visible Infrared Imaging Radiometer Suite (VIIRS) onboard Suomi National Polar-orbiting Partnership (NPP) have been acquired at Centre de Météorologie Spatiale (CMS) in Lannion (Brittany) in direct readout mode since April 2012. CMS is committed to produce sea surface temperature (SST) products from VIIRS data twice a day over an area covering North-East Atlantic and the Mediterranean Sea in the framework of the EUMETSAT Ocean and Sea Ice Satellite Application Facility (OSI-SAF). A cloud mask has been developed and cloud mask control techniques have been implemented. SST algorithms have been defined, as well as quality level attribution rules. Since mid October 2012 a VIIRS SST chain, similar to that used for processing METOP AVHRR has been run in a preoperational mode. The corresponding bias and standard deviation against drifting buoy measurements (mid October 2012 to mid March 2013) are -0.05 and 0.37 K for nighttime and -0.13 and 0.46 K for daytime, respectively. VIIRS derived SST production is expected operational by mid 2013. The OSI-SAF VIIRS derived SST products are compliant with the Group for High Resolution SST (GHRSST) GDS V2.0 format.

  6. The optimal operating temperature of the collector of an irreversible solar-driven refrigerator

    NASA Astrophysics Data System (ADS)

    Lin, Guoxing; Yan, Zijun

    1999-01-01

    A universal irreversible solar-driven refrigerator model is presented, in which not only the irreversibility of heat conduction but also the irreversibilities resulting from the friction, eddies and other irreversible effects inside the working fluid are considered. On the basis of this model and the linear heat-loss model of a solar collector, one of the important parameters, called the optimal operating temperature of the collector of a solar-driven refrigerator, is derived by using the finite-time thermodynamic theory. From the result, the maximum overall coefficient of performance of the refrigerator is determined and some significant problems are discussed. The results obtained here are quite realistic and universal, insofar as all the corresponding results derived by using the reversible and endoreversible models and the model considering only the internal irreversibility cycle can be deduced from them. Thus, they may provide some new theoretical bases for further exploitation of solar-driven refrigerators. Furthermore, some shortcoming in the related literature are pointed out.

  7. Single-ion polymer electrolyte membranes enable lithium-ion batteries with a broad operating temperature range.

    PubMed

    Cai, Weiwei; Zhang, Yunfeng; Li, Jing; Sun, Yubao; Cheng, Hansong

    2014-04-01

    Conductive processes involving lithium ions are analyzed in detail from a mechanistic perspective, and demonstrate that single ion polymeric electrolyte (SIPE) membranes can be used in lithium-ion batteries with a wide operating temperature range (25-80 °C) through systematic optimization of electrodes and electrode/electrolyte interfaces, in sharp contrast to other batteries equipped with SIPE membranes that display appreciable operability only at elevated temperatures (>60 °C). The performance is comparable to that of batteries using liquid electrolyte of inorganic salt, and the batteries exhibit excellent cycle life and rate performance. This significant widening of battery operation temperatures coupled with the inherent flexibility and robustness of the SIPE membranes makes it possible to develop thin and flexible Li-ion batteries for a broad range of applications.

  8. Operations

    ERIC Educational Resources Information Center

    Wilkins, Jesse L. M.; Norton, Anderson; Boyce, Steven J.

    2013-01-01

    Previous research has documented schemes and operations that undergird students' understanding of fractions. This prior research was based, in large part, on small-group teaching experiments. However, written assessments are needed in order for teachers and researchers to assess students' ways of operating on a whole-class scale. In this study,…

  9. Time-resolved nature of exhaust gas emissions and piston wall temperature under transient operation in a small diesel engine

    SciTech Connect

    Reksowardojo, I.K.; Ogawa, Hideyuki; Miyamoto, Noboru; Enomoto, Yoshiteru; Kitamura, Toru

    1996-09-01

    Diesel combustion and exhaust gas emissions under transient operation (when fuel amounts abruptly increased) were investigated under a wide range of operating conditions with a newly developed gas sampling system. The relation between gas emissions and piston wall temperatures was also investigated. The results indicated that after the start of acceleration NOx, THC and smoke showed transient behaviors before reaching the steady state condition. Of the three gases, THC was most affected by piston wall temperature; its concentration decreased as the wall temperature increased throughout the acceleration except immediately after the start of acceleration. The number of cycles, at which gas concentrations reach the steady-state value after the start of acceleration, were about 1.2 times the cycle constant of the piston wall temperature for THC, and 2.3 times for smoke.

  10. Temperature-programmed technique accompanied with high-throughput methodology for rapidly searching the optimal operating temperature of MOX gas sensors.

    PubMed

    Zhang, Guozhu; Xie, Changsheng; Zhang, Shunping; Zhao, Jianwei; Lei, Tao; Zeng, Dawen

    2014-09-08

    A combinatorial high-throughput temperature-programmed method to obtain the optimal operating temperature (OOT) of gas sensor materials is demonstrated here for the first time. A material library consisting of SnO2, ZnO, WO3, and In2O3 sensor films was fabricated by screen printing. Temperature-dependent conductivity curves were obtained by scanning this gas sensor library from 300 to 700 K in different atmospheres (dry air, formaldehyde, carbon monoxide, nitrogen dioxide, toluene and ammonia), giving the OOT of each sensor formulation as a function of the carrier and analyte gases. A comparative study of the temperature-programmed method and a conventional method showed good agreement in measured OOT.

  11. R&D on an Ultra-Thin Composite Membrane for High-Temperature Operation in PEMFC. Final Report

    SciTech Connect

    Yuh, C.-Y.

    2003-10-06

    FuelCell Energy developed a novel high-temperature proton exchange membrane for PEM fuel cells for building applications. The laboratory PEM fuel cell successfully operated at 100-400{supdegree}C and low relative humidity to improve CO tolerance, mitigate water and thermal management challenges, and reduce membrane cost. The developed high-temperature membrane has successfully completed 500h 120C endurance testing.

  12. Multi-cycle operation of enhanced biological phosphorus removal (EBPR) with different carbon sources under high temperature.

    PubMed

    Shen, Nan; Chen, Yun; Zhou, Yan

    2017-05-01

    Many studies reported that it is challenging to apply enhanced biological phosphorus removal (EBPR) process at high temperature. Glycogen accumulating organisms (GAOs) could easily gain their dominance over poly-phosphate accumulating organisms (PAOs) when the operating temperature was in the range of 25 °C-30 °C. However, a few successful EBPR processes operated at high temperature have been reported recently. This study aimed to have an in-depth understanding on the impact of feeding strategy and carbon source types on EBPR performance in tropical climate. P-removal performance of two EBPR systems was monitored through tracking effluent quality and cyclic studies. The results confirmed that EBPR was successfully obtained and maintained at high temperature with a multi-cycle strategy. More stable performance was observed with acetate as the sole carbon source compared to propionate. Stoichiometric ratios of phosphorus and carbon transformation during both anaerobic and aerobic phases were higher at high temperature than low temperature (20±1 °C) except anaerobic PHA/C ratios within most of the sub-cycles. Furthermore, the fractions of PHA and glycogen in biomass were lower compared with one-cycle pulse feed operation. The microbial community structure was more stable in acetate-fed sequencing batch reactor (C2-SBR) than that in propionate-fed reactor (C3-SBR). Accumulibacter Clade IIC was found to be highly abundant in both reactors.

  13. Effect of operating temperatures on the microbial community profiles in a high cell density hybrid anaerobic bioreactor.

    PubMed

    Kundu, Kankana; Sharma, Shilpi; Sreekrishnan, T R

    2012-08-01

    Lack of knowledge about the microbial consortia involved in wastewater treatment at different operating temperatures, is a major reason for failure of anaerobic reactors in field applications. Present study was undertaken to correlate performance of hybrid anaerobic reactors operating at different temperatures (37, 45 and 55 °C) to structures of archaeal and bacterial communities involved. Self-immobilized granules were developed in the reactors continuously fed with synthetic wastewater (10,000 mg COD l(-1)) and operated at an organic loading rate of 2.22 kg COD m(-3) day(-1) and hydraulic retention time of 5 days. The reactor operated at 37 °C showed the best performance as well as the most diverse microbial community revealed by PCR-denaturing gradient gel electrophoresis analysis using 16S rRNA gene amplicons. Sequences derived from reactors operating at higher temperatures revealed presence of different methanogens, but lesser diversity caused a drop in COD degradation capability of the system indicating successful operation at low loading conditions.

  14. Implications of the temperature dependence of Nd:YAG spectroscopic values for low temperature laser operation at 946 nm

    NASA Astrophysics Data System (ADS)

    Yoon, S. J.; Mackenzie, J. I.

    2014-05-01

    We present our measurements of the key spectroscopic properties over the temperature range of 77 K to 450 K for Nd3+ ions doped in Y3Al5O12 (YAG). From room to liquid nitrogen temperature (LNT), the peak absorption cross section around 808 nm increased by almost 3 times, in conjunction the bandwidth of this absorption line reduced by the same factor. At LNT the peak of the absorption line was blue shifted by 0.25 nm with respect to that at 300 K. The fluorescence spectrum between 850 nm - 1450 nm was measured, from which the emission cross sections for the three main transitions were calculated. One note of particular interest for the dominant emission wavelengths around 1064nm and 1061nm (4F3/2 --> 4I11/2) was the switch in their relative strength below 170K, and at LNT the 1061 nm line has almost twice the cross section as at 1064nm.. The fluorescence and lifetime of the upper laser level (4F3/2) was measured and the effective emission cross section determined by the Fuchtbauer-Ladenburg (F-L) method. The effective emission cross section for 946 nm (R1 --> Z5) increased by more than two times over the 300 K to 77 K range. A numerical fit for the temperature dependent emission cross section at 946 nm and 1064 nm and also calculated absorption coefficient at 808 nm pump diode laser have also obtained from the measured spectroscopic data.

  15. The influence of operating temperature on the efficiency of a combined heat and power fuel cell plant

    NASA Astrophysics Data System (ADS)

    Au, S. F.; McPhail, S. J.; Woudstra, N.; Hemmes, K.

    It is generally accepted that the ideal operating temperature of a molten carbonate fuel cell (MCFC) is 650 °C. Nevertheless, when waste heat utilization in the form of an expander and steam production cycle is introduced in the system, another temperature level might prove more productive. This article is a first attempt to the optimization of MCFC operating temperatures of a MCFC system by presenting a case study in which the efficiency of a combined heat and power (CHP) plant is analyzed. The fuel cell plant under investigation is designed around a 250 kW-class MCFC fuelled by natural gas, which is externally reformed by a heat exchange reformer (HER). The operating temperature of the MCFC is varied over a temperature range between 600 and 700 °C while keeping the rest of the system the same as far as possible. Changes in energetic efficiency are given and the causes of these changes are further analyzed. Furthermore, the exergetic efficiencies of the system and the distribution of exergy losses in the system are given. Flowsheet calculations show that there is little dependency on the temperature in the first order. Both the net electrical performance and the overall exergetic performance show a maximum at approximately 675 °C, with an electrical efficiency of 51.9% (LHV), and an exergy efficiency of 58.7%. The overall thermal efficiency of this CHP plant increases from 87.1% at 600 °C to 88.9% at 700 °C. Overall, the change in performance is small in this typical range of MCFC operating temperature.

  16. Prediction of air temperature in the aircraft cabin under different operational conditions

    NASA Astrophysics Data System (ADS)

    Volavý, F.; Fišer, J.; Nöske, I.

    2013-04-01

    This paper deals with the prediction of the air temperature in the aircraft cabin by means of Computational Fluid Dynamics. The simulations are performed on the CFD model which is based on geometry and cabin interior arrangement of the Flight Test Facility (FTF) located at Fraunhofer IBP, Germany. The experimental test flights under three different cabin temperatures were done in FTF and the various data were gathered during these flights. Air temperature in the cabin was measured on probes located near feet, torso and head of each passenger and also surface temperature and air temperature distributed from inlets were measured. The data were firstly analysed in order to obtain boundary conditions for cabin surfaces and inlets. Then the results of air temperature from the simulations were compared with measured data. The suitability and accuracy of the CFD approach for temperature prediction is discussed.

  17. Influence of hydrogen temperature on the stability of a rocket engine combustor operated with hydrogen and oxygen

    NASA Astrophysics Data System (ADS)

    Gröning, Stefan; Hardi, Justin; Suslov, Dmitry; Oschwald, Michael

    2017-03-01

    Since the late 1960s, low hydrogen injection temperature is known to have a destabilising effect on rocket engines with the propellant combination hydrogen/oxygen. Self-excited combustion instabilities of the first tangential mode have been found recently in a research rocket combustor operated with the propellant combination hydrogen/oxygen with a hydrogen temperature of 95 K. A hydrogen temperature ramping experiment has been performed with this research combustor to analyse the impact of hydrogen temperature on the self-excited combustion instabilities. The temperature was varied between 40 and 135 K. Contrary to past results found in literature, the combustor was found to be stable at low hydrogen temperatures while increased oscillation amplitudes of the first tangential mode were found at higher temperatures of around 100 K and above, which is consistent with previous observations of instabilities in this combustor. Further analysis shows that hydrogen temperature has a strong impact on the combustion chamber resonance frequencies. By varying the hydrogen injection temperature, the frequency of the first tangential mode is shifted to coincide with the second longitudinal resonance frequency of the liquid oxygen injector. Excitation of combustion chamber pressure oscillations was observed during such events.

  18. Temperature effects on particulate emissions from DPF-equipped diesel trucks operating on conventional and biodiesel fuels

    EPA Science Inventory

    Two diesel trucks equipped with a particulate filter (DPF) were tested at two ambient temperatures (70oF and 20oF), fuels (ultra low sulfur diesel (ULSD) and biodiesel (B20)) and operating loads (a heavy and light weight). The test procedure included three driving cycles, a cold ...

  19. Animal Thermoregulation and the Operative Environmental (Equivalent) Temperature. Physical Processes in Terrestrial and Aquatic Ecosystems, Transport Process.

    ERIC Educational Resources Information Center

    Stevenson, R. D.

    These materials were designed to be used by life science students for instruction in the application of physical theory to ecosystem operation. Most modules contain computer programs which are built around a particular application of a physical process. Thermoregulation is defined as the ability of an organism to modify its body temperature. This…

  20. AuPd/polyaniline as the anode in an ethylene glycol microfluidic fuel cell operated at room temperature.

    PubMed

    Arjona, N; Palacios, A; Moreno-Zuria, A; Guerra-Balcázar, M; Ledesma-García, J; Arriaga, L G

    2014-08-04

    AuPd/polyaniline was used for the first time, for ethylene glycol (EG) electrooxidation in a novel microfluidic fuel cell (MFC) operated at room temperature. The device exhibits high electrocatalytic performance and stability for the conversion of cheap and fully available EG as fuel.

  1. Performance comparison of long and short-side chain perfluorosulfonic membranes for high temperature polymer electrolyte membrane fuel cell operation

    NASA Astrophysics Data System (ADS)

    Stassi, A.; Gatto, I.; Passalacqua, E.; Antonucci, V.; Arico, A. S.; Merlo, L.; Oldani, C.; Pagano, E.

    A new Aquivion™ E79-03S short-side chain perfluorosulfonic membrane with a thickness of 30 μm (dry form) and an equivalent weight (EW) of 790 g/equiv recently developed by Solvay-Solexis for high-temperature operation was tested in a pressurised (3 bar abs.) polymer electrolyte membrane (PEM) single cell at a temperature of 130 °C. For comparison, a standard Nafion™ membrane (EW 1100 g/equiv) of similar thickness (50 μm) was investigated under similar operating conditions. Both membranes were tested for high temperature operation in conjunction with an in-house prepared carbon supported Pt electrocatalyst. The electrocatalyst consisted of nanosized Pt particles (particle size ∼2 nm) dispersed on a high surface area carbon black. The electrochemical tests showed better performance for the Aquivion™ membrane as compared to Nafion™ with promising properties for high temperature PEM fuel cell applications. Beside the higher open circuit voltage and lower ohmic constraints, a higher electrocatalytic activity was observed at high temperature for the electrocatalyst-Aquivion™ ionomer interface indicating a better catalyst utilization.

  2. State of the art of AIM LWIR and VLWIR MCT 2D focal plane detector arrays for higher operating temperatures

    NASA Astrophysics Data System (ADS)

    Figgemeier, H.; Hanna, S.; Eich, D.; Mahlein, K.-M.; Fick, W.; Schirmacher, W.; Thöt, R.

    2016-05-01

    In this paper AIM presents its latest results on both n-on-p and p-on-n low dark current planar MCT photodiode technology LWIR and VLWIR two-dimensional focal plane detector arrays with a cut-off wavelength >11μm at 80K and a 640x512 pixel format at a 20μm pitch. Thermal dark currents significantly reduced as compared to `Tennant's Rule 07' at a yet good detection efficiency >60% as well as results from NETD and photo response performance characterization are presented. The demonstrated detector performance paces the way for a new generation of higher operating temperature LWIR MCT FPAs with a <30mK NETD up to a 110K detector operating temperature and with good operability.

  3. Internal temperature measurement of an ytterbium doped material under laser operation.

    PubMed

    Petit, J; Viana, B; Goldner, Ph

    2011-01-17

    Temperature of the pumped volume of an ytterbium doped material has been measured while laser action is taking place. This is achieved by recording green emissions at 530 and 550 nm from Er3+ impurities. These emissions result from energy transfer upconversion processes between Yb3+ and Er3+. Experiments performed on a Yb3+:CaGdAlO4 crystal show the effect of pump power and laser wavelength on the sample internal temperature. Temperature variation along the sample length has also been measured. This method can complement data obtained by thermal cameras which can only access surface temperatures in most laser materials.

  4. Effect of low air velocities on thermal homeostasis and comfort during exercise at space station operational temperature and humidity

    NASA Technical Reports Server (NTRS)

    Beumer, Ronald J.

    1989-01-01

    The effectiveness of different low air velocities in maintaining thermal comfort and homeostasis during exercise at space station operational temperature and humidity was investigated. Five male subjects exercised on a treadmill for successive ten minute periods at 60, 71, and 83 percent of maximum oxygen consumption at each of four air velocities, 30, 50, 80, and 120 ft/min, at 22 C and 62 percent relative humidity. No consistent trends or statistically significant differences between air velocities were found in body weight loss, sweat accumulation, or changes in rectal, skin, and body temperatures. Occurrence of the smallest body weight loss at 120 ft/min, the largest sweat accumulation at 30 ft/min, and the smallest rise in rectal temperature and the greatest drop in skin temperature at 120 ft/min all suggested more efficient evaporative cooling at the highest velocity. Heat storage at all velocities was evidenced by increased rectal and body temperatures; skin temperatures declined or increased only slightly. Body and rectal temperature increases corresponded with increased perception of warmth and slight thermal discomfort as exercise progressed. At all air velocities, mean thermal perception never exceeded warm and mean discomfort, greatest at 30 ft/min, was categorized at worst as uncomfortable; sensation of thermal neutrality and comfort returned rapidly after cessation of exercise. Suggestions for further elucidation of the effects of low air velocities on thermal comfort and homeostasis include larger numbers of subjects, more extensive skin temperature measurements and more rigorous analysis of the data from this study.

  5. Sensitive Infrared Photodetectors: Optimized Electron Kinetics for Room-Temperature Operation

    DTIC Science & Technology

    2010-12-20

    photoelectron lifetime (the capture time of photoelectrons) and improve the device responsivity, photoconductive gain, and sensitivity. Combining QD...parameter for improving the efficiency of room-temperature semiconductor optoelectronic devices, such as mid- and far infrared detectors, solar cells... improving the room- temperature optoelectronic devices due to expected slow relaxation between discrete QD levels. These expectations were based on the

  6. Dirac point and transconductance of top-gated graphene field-effect transistors operating at elevated temperature

    SciTech Connect

    Hopf, T.; Vassilevski, K. V. Escobedo-Cousin, E.; King, P. J.; Wright, N. G.; O'Neill, A. G.; Horsfall, A. B.; Goss, J. P.; Wells, G. H.; Hunt, M. R. C.

    2014-10-21

    Top-gated graphene field-effect transistors (GFETs) have been fabricated using bilayer epitaxial graphene grown on the Si-face of 4H-SiC substrates by thermal decomposition of silicon carbide in high vacuum. Graphene films were characterized by Raman spectroscopy, Atomic Force Microscopy, Scanning Tunnelling Microscopy, and Hall measurements to estimate graphene thickness, morphology, and charge transport properties. A 27 nm thick Al₂O₃ gate dielectric was grown by atomic layer deposition with an e-beam evaporated Al seed layer. Electrical characterization of the GFETs has been performed at operating temperatures up to 100 °C limited by deterioration of the gate dielectric performance at higher temperatures. Devices displayed stable operation with the gate oxide dielectric strength exceeding 4.5 MV/cm at 100 °C. Significant shifting of the charge neutrality point and an increase of the peak transconductance were observed in the GFETs as the operating temperature was elevated from room temperature to 100 °C.

  7. Biohydrogen production from kitchen based vegetable waste: effect of pyrolysis temperature and time on catalysed and non-catalysed operation.

    PubMed

    Agarwal, Manu; Tardio, James; Mohan, S Venkata

    2013-02-01

    Pyrolysis of kitchen based vegetable waste (KVW) was studied in a designed packed bed reactor. The effect of process parameters like temperature, time and catalyst on bio-gas yield and its composition was studied. The total bio-gas yield was found to be maximum with non-catalysed operation (260ml/g) at 1073K (180min). Higher hydrogen (H(2)) yield with non-catalysed operation (32.68%) was observed at 1073K (180min) while with catalysed operation the requisite temperature (873K) and time (120min) reduced with both silica gel (33.34%) and sand (41.82%) thus, saving energy input. Methane (CH(4)) yield was found to be highest (4.44times than non-catalysed and 1.42 with silica gel) in presence of sand (71.485ml/g) at medium temperature (873K) and time (60min). The catalyst operation reduced the carbondioxide (CO(2)) share from 47.29% to 41.30% (silica gel catalysed) and 21.91% (sand catalysed) at 873K.

  8. Heat and fuel coupled operation of a high temperature polymer electrolyte fuel cell with a heat exchanger methanol steam reformer

    NASA Astrophysics Data System (ADS)

    Schuller, G.; Vázquez, F. Vidal; Waiblinger, W.; Auvinen, S.; Ribeirinha, P.

    2017-04-01

    In this work a methanol steam reforming (MSR) reactor has been operated thermally coupled to a high temperature polymer electrolyte fuel cell stack (HT-PEMFC) utilizing its waste heat. The operating temperature of the coupled system was 180 °C which is significantly lower than the conventional operating temperature of the MSR process which is around 250 °C. A newly designed heat exchanger reformer has been developed by VTT (Technical Research Center of Finland LTD) and was equipped with commercially available CuO/ZnO/Al2O3 (BASF RP-60) catalyst. The liquid cooled, 165 cm2, 12-cell stack used for the measurements was supplied by Serenergy A/S. The off-heat from the electrochemical fuel cell reaction was transferred to the reforming reactor using triethylene glycol (TEG) as heat transfer fluid. The system was operated up to 0.4 A cm-2 generating an electrical power output of 427 Wel. A total stack waste heat utilization of 86.4% was achieved. It has been shown that it is possible to transfer sufficient heat from the fuel cell stack to the liquid circuit in order to provide the needed amount for vaporizing and reforming of the methanol-water-mixture. Furthermore a set of recommendations is given for future system design considerations.

  9. Effect of lubricant jet location on spiral bevel gear operating temperatures

    NASA Technical Reports Server (NTRS)

    Handschuh, Robert F.

    1992-01-01

    An experimental study was conducted to determine the effect of lubricant jet location on spiral bevel gear bulk temperatures. Transient surface temperatures were also measured. Tests were conducted on aircraft quality spiral bevel gears in a closed loop test facility. Thermocoupled pinions and an infrared microscope were used to collect the pertinent data. A single fan jet lubricated the test gears. Lubricant flow rate (lubricant jet pressure) and applied torque were also varied. The results showed that jet placement had a significant effect on the gear bulk temperatures.

  10. Effect of lubricant jet location on spiral bevel gear operating temperatures

    NASA Astrophysics Data System (ADS)

    Handschuh, Robert F.

    1992-04-01

    An experimental study was conducted to determine the effect of lubricant jet location on spiral bevel gear bulk temperatures. Transient surface temperatures were also measured. Tests were conducted on aircraft quality spiral bevel gears in a closed loop test facility. Thermocoupled pinions and an infrared microscope were used to collect the pertinent data. A single fan jet lubricated the test gears. Lubricant flow rate (lubricant jet pressure) and applied torque were also varied. The results showed that jet placement had a significant effect on the gear bulk temperatures.

  11. The low temperature differential Stirling engine with working fluid operated on critical condition

    SciTech Connect

    Naso, V.; Dong, W.; Lucentini, M.; Capata, R.

    1998-07-01

    The research and development of low temperature differential Stirling engine has a great potential market since a lot of thermal energy at low temperature can supply it and the cost of this kind of engine is lower than general Stirling engine. The characteristics of low compression ratio and low differential temperature Stirling engine may be satisfied with working fluid compressed on critical conditions. By combining two phase heat transfer with forced convective flow in compression space and through the regenerator in the engine, a new heat transfer coefficient emerges capable of absorbing and releasing high heat fluxes without the corresponding low temperature increase. The current analysis focuses on the study of Stirling engines with working fluid compressed on critical conditions, thus at two-phase heat transfer in compression space and regenerator of the engine under forced convective flow conditions.

  12. EVALUATION OF ROTARY KILN INCINERATOR OPERATION AT LOW TO MODERATE TEMPERATURE CONDITIONS VOLUME 1. TECHNICAL RESULTS

    EPA Science Inventory

    A test program was performed at the Environmental Protection Agency Incineration Research Facility to study the effectiveness of incineration at low-to-moderate temperatures in decontaminating soils containing organic compounds with different volatilities (boiling points). The da...

  13. A study on positive-feedback configuration of a bipolar SiC high temperature operational amplifier

    NASA Astrophysics Data System (ADS)

    Kargarrazi, Saleh; Lanni, Luigia; Zetterling, Carl-Mikael

    2016-02-01

    This paper reports on the design and implementation of an integrated operational amplifier in bipolar SiC, and elaborates on its operation in positive-feedback configuration.The opamp is studied in different feedback setups: closed-loop compensated amplifier, comparator with hysteresis (Schmitt trigger), and as a relaxation oscillator. Measurement results suggest a stable closed-loop opamp with ∼40 dB gain, a Schmitt trigger with constant threshold levels over a wide temperature range, and a relaxation oscillator tested up to 540 kHz. All the setups were tested from 25 °C up to 500 °C.

  14. EVALUATION OF ROTARY KILN INCINERATOR OPERATION AT LOW TO MODERATE TEMPERATURE CONDITIONS VOLUME 2. APPENDICES

    EPA Science Inventory

    A test program was performed at the Environmental Protection Agency Incineration Research Facility to study the effectiveness of incineration at low-to-moderate volatilities (boiling points). The data in the Appendix contain: incinerator operating data, laboratory analyses, sampl...

  15. High temperature solar power tower plants - Concept considerations and operational criteria

    NASA Astrophysics Data System (ADS)

    Cefaratti, C.; Gretz, J.

    Conceptual considerations and operational criteria are described for central receiver/distributed heliostat reflector solar power plants, based on experience gained to date with Eurelios, a European Economic Community 1 MW powerplant now under construction in Italy. This installation is described with respect to economic, material, operational and performance requirements, which indicate that there are as yet few grounds for optimism regarding the large-scale implementation of such technology.

  16. Li-Ion Batteries for Space Applications: High Specific Energy and Wide-Operating Temperature

    NASA Technical Reports Server (NTRS)

    Smart, Marshall; Whitacre, Jay; West, William; Manthiram, A.; Prakash, G. K. S; Bugga, Ratnakumar

    2006-01-01

    Compared to the conventional Ni-Co oxides (with or without AI additions), the NMC (1/3:1/3:1/3) cathode provides marginal improvement in specific capacity. However, some of the formulations based on the solid solutions of layered Li2Mn03 and LiM02 (M = Mn0.5Ni0.5} have shown capacities as high as 250 mAh/g, combined with high cell voltages (4.5 V) and with the likelihood of enhanced thermal stability. Multi-component electrolytes with low EC-proportions and selected co-solvents provide significant improvement in the low temperature performance, down to -60 C, combined with the non-flammable attribute from the co-solvents. The NMC cathode shows good compatibility with the carbonate-based low temperature electrolytes. Impressive performances have been realized at low temperatures of <= 30 C. Electrolytes with high salt concentration and high EC content fare well at room temperatures, while the formulations with low EC content and low salt concentration are preferred at low temperatures. DPA studies reveal increased SEI growth on the electrodes, especially anode, upon irradiation. Performance of low temperature electrolytes in prototype cells corroborate the findings from laboratory cells.

  17. Air conditioner operation behaviour based on students' skin temperature in a classroom.

    PubMed

    Song, Gook-Sup; Lim, Jae-Han; Ahn, Tae-Kyung

    2012-01-01

    A total of 25 college students participated in a study to determine when they would use an air conditioner during a lecture in a university classroom. The ambient temperature and relative humidity were measured 75 cm above the floor every minute. Skin temperatures were measured every minute at seven points, according to the recommendation of Hardy and Dubois. The average clothing insulation value (CLO) of subjects was 0.53 ± 0.07 CLO. The mean air velocity in the classroom was 0.13 ± 0.028 m/s. When the subjects turned the air conditioner both on and off, the average ambient temperatures, relative humidity and mean skin temperatures were 27.4 and 23.7 °C (p = 0.000), 40.9 and 40.0% (p = 0.528) and 32.7 and 32.2 °C (p = 0.024), respectively. When the status of the air conditioner was changed, the differences of skin temperatures in core body parts (head, abdomen and thigh) were not statistically significant. However, in the extremities (mid-lower arm, hand, shin and instep), the differences were statistically significant. Subjects preferred a fluctuating environment to a constant temperature condition. We found that a changing environment does not affect classroom study.

  18. Investigation of poly(o-anisidine)-SnO2 nanocomposites for fabrication of low temperature operative liquefied petroleum gas sensor

    NASA Astrophysics Data System (ADS)

    Patil, Dewyani; Kolhe, Kishor; Potdar, Hari S.; Patil, Pradip

    2011-12-01

    Poly(o-anisidine)-tin oxide (POA-SnO2) nanocomposites has been investigated for the fabrication of low temperature operative (100 °C) liquefied petroleum gas (LPG) sensor. The POA-SnO2 nanocomposites have been synthesized through an in situ chemical polymerization of o-anisidine in presence of SnO2 nanoparticles. The POA-SnO2 nanocomposite shows better LPG sensing properties than that of pure POA. The nanocomposite with 50 wt. % SnO2 exhibits an excellent LPG sensing characteristics at the operating temperature of 100 °C such as higher relative gas response (˜23.47% to 3.4% of LPG), extremely rapid response (˜6 s), fast recovery (˜33 s), good reproducibility, and remarkable selectivity. The application of POA-SnO2 nanocomposites for fabrication of the LPG sensor was demonstrated.

  19. Dynamic gas temperature measurement system. Volume 2: Operation and program manual

    NASA Technical Reports Server (NTRS)

    Purpura, P. T.

    1983-01-01

    The hot section technology (HOST) dynamic gas temperature measurement system computer program acquires data from two type B thermocouples of different diameters. The analysis method determines the in situ value of an aerodynamic parameter T, containing the heat transfer coefficient from the transfer function of the two thermocouples. This aerodynamic parameter is used to compute a fequency response spectrum and compensate the dynamic portion of the signal of the smaller thermocouple. The calculations for the aerodynamic parameter and the data compensation technique are discussed. Compensated data are presented in either the time or frequency domain, time domain data as dynamic temperature vs time, or frequency domain data.

  20. Air Ambient-Operated pNIPAM-Based Flexible Actuators Stimulated by Human Body Temperature and Sunlight.

    PubMed

    Yamamoto, Yuki; Kanao, Kenichiro; Arie, Takayuki; Akita, Seiji; Takei, Kuniharu

    2015-05-27

    Harnessing a natural power source such as the human body temperature or sunlight should realize ultimate low-power devices. In particular, macroscale and flexible actuators that do not require an artificial power source have tremendous potential. Here we propose and demonstrate electrically powerless polymer-based actuators operated at ambient conditions using a packaging technique in which the stimulating power source is produced by heat from the human body or sunlight. The actuating angle, force, and reliability are discussed as functions of temperature and exposure to sunlight. Furthermore, a wearable device platform and a smart curtain actuated by the temperature of human skin and sunlight, respectively, are demonstrated as the first proof-of-concepts. These nature-powered actuators should realize a new class of ultimate low-power devices.

  1. Cs vapor microcells with Ne-He buffer gas mixture for high operation-temperature miniature atomic clocks.

    PubMed

    Kroemer, E; Abdel Hafiz, M; Maurice, V; Fouilland, B; Gorecki, C; Boudot, R

    2015-07-13

    We report on the characterization of Cs vapor microfabricated cells filled with a Ne-He buffer gas mixture using coherent population trapping (CPT) spectroscopy. The temperature dependence of the Cs clock frequency is found to be canceled at the first order around a so-called inversion temperature higher than 80°C whose value depends on the buffer gas partial pressure ratio. This buffer gas mixture could be well-adapted for the development of miniature atomic clocks devoted to be used in specific applications such as defense and avionic systems with high operating temperature environment (typically higher than 85°C). This solution suggests an alternative to buffer gas mixtures generally used in optically-pumped vapor cell atomic clocks.

  2. The electrolyte challenge for a direct methanol-air polymer electrolyte fuel cell operating at temperatures up to 200 C

    NASA Technical Reports Server (NTRS)

    Savinell, Robert; Yeager, Ernest; Tryk, Donald; Landau, Uziel; Wainright, Jesse; Gervasio, Dominic; Cahan, Boris; Litt, Morton; Rogers, Charles; Scherson, Daniel

    1993-01-01

    Novel polymer electrolytes are being evaluated for use in a direct methanol-air fuel cell operating at temperatures in excess of 100 C. The evaluation includes tests of thermal stability, ionic conductivity, and vapor transport characteristics. The preliminary results obtained to date indicate that a high temperature polymer electrolyte fuel cell is feasible. For example, Nafion 117 when equilibrated with phosphoric acid has a conductivity of at least 0.4 Omega(exp -1)cm(exp -1) at temperatures up to 200 C in the presence of 400 torr of water vapor and methanol vapor cross over equivalent to 1 mA/cm(exp 2) under a one atmosphere methanol pressure differential at 135 C. Novel polymers are also showing similar encouraging results. The flexibility to modify and optimize the properties by custom synthesis of these novel polymers presents an exciting opportunity to develop an efficient and compact methanol fuel cell.

  3. Ultrasensitive Room-Temperature Operable Gas Sensors Using p-Type Na:ZnO Nanoflowers for Diabetes Detection.

    PubMed

    Jaisutti, Rawat; Lee, Minkyung; Kim, Jaeyoung; Choi, Seungbeom; Ha, Tae-Jun; Kim, Jaekyun; Kim, Hyoungsub; Park, Sung Kyu; Kim, Yong-Hoon

    2017-03-15

    Ultrasensitive room-temperature operable gas sensors utilizing the photocatalytic activity of Na-doped p-type ZnO (Na:ZnO) nanoflowers (NFs) are demonstrated as a promising candidate for diabetes detection. The flowerlike Na:ZnO nanoparticles possessing ultrathin hierarchical nanosheets were synthesized by a facile solution route at a low processing temperature of 40 °C. It was found that the Na element acting as a p-type dopant was successfully incorporated in the ZnO lattice. On the basis of the synthesized p-type Na:ZnO NFs, room-temperature operable chemiresistive-type gas sensors were realized, activated by ultraviolet (UV) illumination. The Na:ZnO NF gas sensors exhibited high gas response (S of 3.35) and fast response time (∼18 s) and recovery time (∼63 s) to acetone gas (100 ppm, UV intensity of 5 mW cm(-2)), and furthermore, subppm level (0.2 ppm) detection was achieved at room temperature, which enables the diagnosis of various diseases including diabetes from exhaled breath.

  4. Stress Evaluation while Prolonged Driving Operation Using the Facial Skin Temperature

    NASA Astrophysics Data System (ADS)

    Asano, Hirotoshi; Muto, Takumi; Ide, Hideto

    There is a relation to the accident of a car and the physiological and psychological state of a driver. The stress may lead to the fall of a fatigue or attentiveness. Therefore, it is an important subject from viewpoint such as accident prevention to evaluate the mental state of a driver. The study aimed at the development of a quantitative instrumentation technology of the stress when a subject is driving for a long time. First of all, we measured the physiological and psychological stress of a driver. The facial skin temperature and ventricular rate that was driver's physiological amount were measured and compared it with visual analog scale of the subjective amount. It was able to be obtaining of the high correlation in facial skin temperature and visual analog scale from the outcome of the experiment. Therefore, the possibility of appreciable of driver's stress at a facial skin temperature was shown. As a result of the experiment, we showed a possibility that facial skin temperature could evaluate long driving stress.

  5. Numerical Simulations of Evaporating Sprays in High Pressure and Temperature Operating Conditions (Engine Combustion Network [ECN])

    DTIC Science & Technology

    2014-05-01

    Modeling for Surrogate Fuels (LLNL-CONF-404514). In the 7th COMODIA International Conference on Modeling and Diagnostics for Advanced Engine Systems...diesel engine operating conditions. The objective of this report is to demonstrate the modeling capability of a recently adopted 3D-Computational Fluid...6 3.3 Spray Modeling

  6. Soft metal plating enables hard metal seal to operate successfully in low temperature, high pressure environment

    NASA Technical Reports Server (NTRS)

    Lamvermeyer, D. J.

    1967-01-01

    Soft metal plating of hard metal lip seal enables successful operation of seal in a cryogenic fluid line under high pressure. The seal is coated with a thin film of 24 carat gold on the lip area to provide antigall and seal properties.

  7. Evaluation of rotary kiln incinerator operation at low-to-moderate temperature conditions. Volume 2. Appendices

    SciTech Connect

    Lee, J.; Fournier, D.; King, C.; Venkatesh, S.; Goldman, C.

    1996-09-01

    A test program was performed at the Environmental Protection Agency Incineration Research Facility to study the effectiveness of incineration at low-to-moderate volatilities (boiling points). The data in the Appendix contain: incinerator operating data, laboratory analyses, sample train worksheets, and data analysis worksheets.

  8. Single Temperature Liquefaction process at different operating pHs to improve ethanol production from Indian rice and corn feedstock.

    PubMed

    Gohel, V; Ranganathan, K; Duan, G

    2016-10-13

    Conventional grain ethanol manufacturing is a high-temperature energy-intensive process comprising of multiple-unit operations when combined with lower ethanol recovery results in higher production cost. In liquefaction, jet cooking accounts for significant energy cost, while strong acid or base used for pH adjustment presents a safety hazard. A need is felt for sustainable ethanol manufacturing process that is less hazardous, consumes lower energy, and operates in a low pH range of 4.50-5.50. A single temperature liquefaction (STL) process that could efficiently operate at lower liquefaction temperature over a pH range of 4.50-5.50 was developed using rice and corn feedstock. Ethanol recovery witnessed at pH 4.5, 5.0, and 5.5 are 481.2 ± 1.5, 492.4 ± 1.5, and 493.6 ± 1.5 L MT(-1) rice, respectively. Similarly, ethanol recovery witnessed at pH 4.5, 5.0, and 5.5 are 404.6 ± 1.3, 413.9 ± 0.8, and 412.4 ± 1.8 L MT(-1) corn, respectively. The improvement in ethanol recovery is attributed to higher starch conversion by alpha-amylase even at pH as low as 4.50. Thus, the STL process operated at pH lower than 5.20 is poised to enhance sustainability by offering dual advantage of energy as well as chemical saving.

  9. The First Air-Temperature Measurements for the Purposes of Battlefield Operations?.

    NASA Astrophysics Data System (ADS)

    Lindgré, S.; Neumann, J.

    1986-03-01

    Close to the end of the severe winter 1808/09, a Russian force crossed the ice-bound Gulf of Bothnia from Finland to Sweden with the purpose of forcing Sweden to desist from taking sides with Great Britain against Napoléon. General major von Berg, one of the commanders of the force, took meteorological observations, including air-temperature measurements, during the crossing, a record of which he left behind in a journal. These air-temperature measurements appear to be the first of their kind in the history of land-based military forces.In the discussion of the meteorological conditions of the above-mentioned harsh winter, use is made of unpublished meteorological measurements at Umcaå, Sweden, and at Ylitomio (Över-Torneå), Finland. The latter were conducted by Johan Portin, a pioneer of meteorological observations near the Arctic Circle.

  10. Non-contact passive temperature measuring system and method of operation using micro-mechanical sensors

    SciTech Connect

    2000-04-18

    A non-contact infrared thermometer measures target temperatures remotely without requiring the ratio of the target size to the target distance to the thermometer. A collection means collects and focuses target IR radiation on an IR detector. The detector measures thermal energy of the target over a spectrum using micromechanical sensors. A processor means calculates the collected thermal energy in at least two different spectral regions using a first algorithm in program form and further calculates the ratio of the thermal energy in the at least two different spectral regions to obtain the target temperature independent of the target size, distance to the target and emissivity using a second algorithm in program form.

  11. Non-contact passive temperature measuring system and method of operation using micro-mechanical sensors

    DOEpatents

    Thundat, Thomas G.; Oden, Patrick I.; Datskos, Panagiotis G.

    2000-01-01

    A non-contact infrared thermometer measures target temperatures remotely without requiring the ratio of the target size to the target distance to the thermometer. A collection means collects and focusses target IR radiation on an IR detector. The detector measures thermal energy of the target over a spectrum using micromechanical sensors. A processor means calculates the collected thermal energy in at least two different spectral regions using a first algorithm in program form and further calculates the ratio of the thermal energy in the at least two different spectral regions to obtain the target temperature independent of the target size, distance to the target and emissivity using a second algorithm in program form.

  12. Preliminary operational results of the low temperature-solar industrial-process-heat field tests

    NASA Astrophysics Data System (ADS)

    Kutscher, C. F.; Davenport, R. L.

    1981-06-01

    Three hot water systems and four hot air systems are evaluated. All are low-temperature projects (process heat at temperatures below 212O F). Performance results, project costs, and problems encountered are summarized. Flat-plate, evacuated-tube, and line-focus collectors are all represented in the program, with collector array areas ranging from 2500 to 21,000 sq ft. Collector array efficiencies ranged from 12% to 36% with net system efficiences from 8% to 33%. Low efficiencies are attributable in some cases to high thermal losses and, for the two projects using air collectors, are due in part to high parasitic power consumption. Problems have included industrial effluents on collectors, glazing and absorber surface failures, excessive thermal losses, freezing and overheating, control problems, and data acquisition system failure. With design and data acquisition costs excluded costs of the projects ranged from $25/sq ft to $87/sq ft and $499/MBtu/yr to $1537/MBtu/yr.

  13. High Precision Piezoelectric Linear Motors for Operations at Cryogenic Temperatures and Vacuum

    NASA Technical Reports Server (NTRS)

    Wong, D.; Carman, G.; Stam, M.; Bar-Cohen, Y.; Sen, A.; Henry, P.; Bearman, G.; Moacanin, J.

    1995-01-01

    The Jet Propulsion Laboratory evaluated the use of an electromechanical device for optically positioning a mirror system during the pre-project phase of the Pluto-Fast-Flyby (PFF) mission. The device under consideration was a piezoelectric driven linear motor functionally dependent upon a time varying electric field which induces displacements ranging from submicrons to millimeters with positioning accuracy within nanometers. Using a control package, the mirror system provides image motion compensation and mosaicking capabilities. While this device offers unique advantages, there were concerns pertaining to its operational capabilities for the PFF mission. The issues include irradiation effects and thermal concerns. A literature study indicated that irradiation effects will not significantly impact the linear motor's operational characteristics. On the other hand, thermal concerns necessitated an in depth study.

  14. Accurate ampacity determination: Temperature-Sag Model for operational real time ratings

    SciTech Connect

    Seppa, T.O.

    1995-07-01

    This report presents a method for determining transmission line ratings based on the relationship between the conductor`s temperature and its sag. The method is based on the Ruling Span principle and the use of transmission line tension monitoring systems. The report also presents a method of accurately calibrating the final sag of the conductor and determining the actual Ruling Span length of the line sections between deadend structures. Main error sources for two other real time methods are also examined.

  15. US Army Test and Evaluation Command Test Operations Procedure ’Temperature-Measuring Devices’

    DTIC Science & Technology

    1982-11-30

    to 20150 C (i0850 to 36590 F). 3.12.2 Crayons , Pellets, Paints. Mineral mixtures of definite melting tempera- tures are available commercially in the...temperature-measuring devices discussed thus far are limited to measurements below a few thoLusand degrees Fahrenheit, since the materials employed would melt ...require no specific technical knowledge: 1) pyrometric cones, 2) crayons , pellets, and paints, and 3) color indicators. 3.12.1 Pyrometric Cones. These are

  16. Temperature-dependent spectroscopy and microchip laser operation of Nd:KGd(WO4)2

    NASA Astrophysics Data System (ADS)

    Loiko, P.; Yoon, S. J.; Serres, J. M.; Mateos, X.; Beecher, S. J.; Birch, R. B.; Savitski, V. G.; Kemp, A. J.; Yumashev, K.; Griebner, U.; Petrov, V.; Aguiló, M.; Díaz, F.; Mackenzie, J. I.

    2016-08-01

    High-resolution absorption and stimulated-emission cross-section spectra are presented for monoclinic Nd:KGd(WO4)2 (Nd:KGW) laser crystals in the temperature range 77-450 K. At room-temperature, the maximum stimulated emission cross-section is σSE = 21.4 × 10-20 cm2 at 1067.3 nm, for light polarization E || Nm. The lifetime of the 4F3/2 state of Nd3+ in KGW is practically temperature independent at 115 ± 5 μs. Measurement of the energy transfer upconversion parameter for a 3 at.% Nd:KGW crystal proved that this was significantly smaller than for alternative hosts, ∼2.5 × 10-17 cm3/s. When cut along the Ng optical indicatrix axis, the Nd:KGW crystal was configured as a microchip laser, generating ∼4 W of continuous-wave output at 1067 nm with a slope efficiency of 61% under diode-pumping. Using a highly-doped (10 at.%) Nd:KGW crystal, the slope efficiency reached 71% and 74% when pumped with a laser diode and a Ti:Sapphire laser, respectively. The concept of an ultrathin (250 μm) Nd:KGW microchip laser sandwiched between two synthetic diamond heat-spreaders is demonstrated.

  17. Discriminating among different tea leaves using an operating temperature-modulated tin oxide gas sensor

    NASA Astrophysics Data System (ADS)

    Rastkhadiv, Ali; Jenabi, Amin; Souri, Asma

    2016-03-01

    We report distinguishing different types of tea leaves from each other based on their aroma using a thermal shock-induced generic tin oxide gas sensor. The sensor used in this work consists of a microheater and a tin oxide pellet, both connected to outside circuitry with noble metal contacts. The heater is powered with a series of narrow high magnitude voltage impulses of predetermined thermal impacts adjusted to produce step-like temperature rises of different magnitudes on the gas sensitive pellet. The sensor is exposed to aromas collected from various types of tea leaves at different concentrations. Within 4.5 s, nine 500 ms-wide voltage pulses, each as high as 9.3 V in magnitude, are applied to the microheater. Each pulse causes a step-like temperature jump on the pellet temperature. The transient responses recorded for different tea leaves look different even after amplitude normalization. The sensor profiles are recorded, digitized, and compared with the database of previous experiences. A heuristically defined high dimensional feature vector is automatically generated for each analyte. Classifications are graphically achieved in a 3-D feature space after applying principle component analysis for dimension reduction.

  18. Temperature Control and Noise Reduction in our Compact ADR System for TES Microcalorimeter Operation

    NASA Astrophysics Data System (ADS)

    Hishi, U.; Fujimoto, R.; Kamiya, K.; Kotake, M.; Ito, H.; Kaido, T.; Tanaka, K.; Hattori, K.

    2016-08-01

    We have been developing a compact adiabatic demagnetization refrigerator, keeping ground application and future missions in mind. A salt pill fabricated in-house, a superconducting magnet with a passive magnetic shield around it, and a mechanical heat switch are mounted in a dedicated helium cryostat. The detector stage temperature is regulated by PID control of the magnet current, with a dI/dt term added to compensate the temperature rise due to parasitic heat. The temperature fluctuation of the detector stage is 1-2 \\upmu Krms, and the hold time was extended by about 15 % thanks to the dI/dt term. Bundle shields of the harnesses between the cryostat and the analog electronics boxes were connected to the chassis at both ends, and the analog electronics boxes were grounded to the cryostat through the bundle shields. This reduced the readout noise to 16 pA/√{Hz} in the 10-60 kHz range. Using this system, an energy resolution of 3.8 ± 0.2 eV (FWHM) was achieved at 5.9 keV.

  19. Room temperature Dy:YLF laser operation at 4.34 micron

    NASA Technical Reports Server (NTRS)

    Barnes, Norman P.; Allen, Roger E.

    1991-01-01

    A Dy:YLF laser operating on the 6H11/2 to 6H13/2 transition at 4.34 micron and using a laser pumping scheme is reported. This pumping scheme is necessitated by the short upper-laser-level lifetime and the small effective stimulated-emission cross section. A suitable laser for this application is the Er:YLF laser operating at 1.73 micron. A simple model that approximates Dy:YLF laser performance well is presented. Results on laser performance, including a determination of the slope efficiency and threshold as a function of the output mirror reflectivity and a correlation of the pulse length with the laser output energy, are reported. Overall laser efficiency is found to be limited primarily by the ratio of the pump wavelength to laser output wavelength and the terminated four-level laser operation. Spectroscopic results, including the measurement of the absorption spectra and the lifetimes of both the upper- and lower-laser manifolds, are given.

  20. Design modification for the modular helium reactor for higher temperature operation and reliability studies for nuclear hydrogen production processes

    NASA Astrophysics Data System (ADS)

    Reza, S. M. Mohsin

    Design options have been evaluated for the Modular Helium Reactor (MHR) for higher temperature operation. An alternative configuration for the MHR coolant inlet flow path is developed to reduce the peak vessel temperature (PVT). The coolant inlet path is shifted from the annular path between reactor core barrel and vessel wall through the permanent side reflector (PSR). The number and dimensions of coolant holes are varied to optimize the pressure drop, the inlet velocity, and the percentage of graphite removed from the PSR to create this inlet path. With the removal of ˜10% of the graphite from PSR the PVT is reduced from 541°C to 421°C. A new design for the graphite block core has been evaluated and optimized to reduce the inlet coolant temperature with the aim of further reduction of PVT. The dimensions and number of fuel rods and coolant holes, and the triangular pitch have been changed and optimized. Different packing fractions for the new core design have been used to conserve the number of fuel particles. Thermal properties for the fuel elements are calculated and incorporated into these analyses. The inlet temperature, mass flow and bypass flow are optimized to limit the peak fuel temperature (PFT) within an acceptable range. Using both of these modifications together, the PVT is reduced to ˜350°C while keeping the outlet temperature at 950°C and maintaining the PFT within acceptable limits. The vessel and fuel temperatures during low pressure conduction cooldown and high pressure conduction cooldown transients are found to be well below the design limits. The reliability and availability studies for coupled nuclear hydrogen production processes based on the sulfur iodine thermochemical process and high temperature electrolysis process have been accomplished. The fault tree models for both these processes are developed. Using information obtained on system configuration, component failure probability, component repair time and system operating modes

  1. Operation of the Airmodus A11 nano Condensation Nucleus Counter at various inlet pressures, various operation temperatures and design of a new inlet system

    NASA Astrophysics Data System (ADS)

    Kangasluoma, J.; Franchin, A.; Duplissy, J.; Ahonen, L.; Korhonen, F.; Attoui, M.; Mikkilä, J.; Lehtipalo, K.; Vanhanen, J.; Kulmala, M.; Petäjä, T.

    2015-08-01

    Measuring sub-3 nm particles outside of controlled laboratory conditions is a challenging task, as many of the instruments are operated at their limits and are subjected to changing ambient conditions. In this study, we advance the current understanding on the operation of Airmodus A11 nano Condensation Nucleus Counter (nCNC), which consists of a A10 Particle Size Magnifier (PSM) and A20 condensation particle counter (CPC). We explore the effect of the inlet line pressure on the measured particle concentration. We identify two different regions inside the instrument where supersaturation of working fluid can take place. We show the possibility of varying the cut-off of the instrument from 1 to 6 nm, a wider size range than the one usually covered by the PSM. We also present a new inlet system, which allows automated measurements of the background, minimizes the diffusion losses in the sampling line and is equipped with an electrostatic filter to remove ions. Finally, our view of the guidelines for optimal use of the Airmodus nCNC are provided.

  2. High temperature electrolyte supported Ni-GDC/YSZ/LSM SOFC operation on two-stage Viking gasifier product gas

    NASA Astrophysics Data System (ADS)

    Hofmann, Ph.; Schweiger, A.; Fryda, L.; Panopoulos, K. D.; Hohenwarter, U.; Bentzen, J. D.; Ouweltjes, J. P.; Ahrenfeldt, J.; Henriksen, U.; Kakaras, E.

    This paper presents the results from a 150 h test of a commercial high temperature single planar solid oxide fuel cell (SOFC) operating on wood gas from the Viking two-stage fixed-bed downdraft gasifier, which produces an almost tar-free gas, that was further cleaned for particulates, sulphur and tar traces. The chosen SOFC was electrolyte supported with a nickel/gadolinium-doped cerium oxide (Ni-GDC) anode, known for its carbon deposition resistance. Through humidification the steam to carbon ratio (S/C) was adjusted to 0.5, which results in a thermodynamically carbon free condition at the SOFC operating temperature T = 850 °C. The cell operated with a fuel utilisation factor (U f) around 30% and a current density of 260 mA cm -2 resulting in an average power density of 207 mW cm -2. Throughout the duration of the test, only a minor cell overpotential increase of 10 mV was observed. Nevertheless, the V- j (voltage-current density) curves on H 2/N 2 before and after the wood gas test proved identical. Extensive SEM/EDS examination of the cell's anode showed that there was neither carbon deposition nor significant shifts in the anode microstructure or contamination when compared to an identical cell tested on H 2/N 2 only.

  3. Neoplasms treatment by diode laser with and without real time temperature control on operation zone

    NASA Astrophysics Data System (ADS)

    Belikov, Andrey V.; Gelfond, Mark L.; Shatilova, Ksenia V.; Sosenkova, Svetlana A.; Lazareva, Anastasia A.; Semyashkina, Yulia V.

    2016-04-01

    Results of nevus, papilloma, dermatofibroma, and basal cell skin cancer in vivo removal by a 980+/-10 nm diode laser with "blackened" tip operating in continuous (CW) mode and automatic power control (APC) mode are presented. The collateral damage width and width of graze wound area around the collateral damage area were demonstrated. The total damage area width was calculated as sum of collateral damage width and graze wound area width. The mean width of total damage area reached 1.538+/-0.254 mm for patient group with nevus removing by 980 nm diode laser operating in CW mode, papilloma - 0.586+/-0.453 mm, dermatofibroma - 1.568+/-0.437 mm, and basal cell skin cancer - 1.603+/-0.613 mm. The mean width of total damage area reached 1.201+/-0.292 mm for patient group with nevus removing by 980 nm diode laser operating in APC mode, papilloma - 0.413+/-0.418 mm, dermatofibroma - 1.240+/-0.546 mm, and basal cell skin cancer - 1.204+/-0.517 mm. It was found that using APC mode decreases the total damage area width at removing of these nosological neoplasms of human skin, and decreases the width of graze wound area at removing of nevus and basal cell skin cancer. At the first time, the dynamic of output laser power and thermal signal during laser removal of nevus in CW and APC mode is presented. It was determined that output laser power during nevus removal for APC mode was 1.6+/-0.05 W and for CW mode - 14.0+/-0.1 W. This difference can explain the decrease of the total damage area width and width of graze wound area for APC mode in comparison with CW mode.

  4. High-mobility low-temperature ZnO transistors with low-voltage operation

    NASA Astrophysics Data System (ADS)

    Bong, Hyojin; Lee, Wi Hyoung; Lee, Dong Yun; Kim, Beom Joon; Cho, Jeong Ho; Cho, Kilwon

    2010-05-01

    Low voltage high mobility n-type thin film transistors (TFTs) based on sol-gel processed zinc oxide (ZnO) were fabricated using a high capacitance ion gel gate dielectric. The ion gel gated solution-processed ZnO TFTs were found to exhibit excellent electrical properties. TFT carrier mobilities were 13 cm2/V s, ON/OFF current ratios were 105, regardless of the sintering temperature used for the preparation of the ZnO thin films. Ion gel gated ZnO TFTs are successfully demonstrated on plastic substrates for the large area flexible electronics.

  5. Method to Measure Total Noise Temperature of a Wireless Receiver During Operation

    NASA Technical Reports Server (NTRS)

    Young, Lawrence E.; Esterhuizen, Stephan; Turbiner, Dmitry

    2013-01-01

    A method has been developed to measure the total effective noise power in a GPS receiver, including contributions from the system temperature, the antenna temperature, interference, lossy components, etc. A known level of noise is periodically injected before the preamplifier during normal tracking, with a switch set to a very low duty cycle, so that there is insignificant signal loss for the GPS signals being tracked. Alternately, a signal of known power may be injected. The coupling port is fed with a switch that can be controlled from the receiver s digital processing section. The switch can connect the coupling port to a noise or signal source at a known power level. The combined system noise is measured, and nearly continuous noise calibrations are made. The effect from injected noise/signals on the performance of the GPS receiver can be less than 0.01 dB of SNR loss. Minimal additional components are required. The GPS receiver is used to measure the SNRs required to solve for the noise level. Because this measurement is referenced to the preamplifier input, it is insensitive to variations in the receiver gain.

  6. Polarization characteristics of a low catalyst loading PEM water electrolyzer operating at elevated temperature

    NASA Astrophysics Data System (ADS)

    Lee, Byung-Seok; Park, Hee-Young; Choi, Insoo; Cho, Min Kyung; Kim, Hyoung-Juhn; Yoo, Sung Jong; Henkensmeier, Dirk; Kim, Jin Young; Nam, Suk Woo; Park, Sehkyu; Lee, Kwan-Young; Jang, Jong Hyun

    2016-03-01

    The effect of temperature and pressure, and diffusion layer thickness is assessed on performance of a proton exchange membrane water electrolyzers (PEMWEs) with an ultralow iridium oxide (IrO2) loading (0.1 mg cm-2) anode prepared by electrodeposition and a Pt/C catalyzed cathode with a Pt loading of 0.4 mg cm-2. Increasing pressure to 2.5 bar at 120 °C enhances the water electrolysis current, so the anode electrodeposited with 0.1 mg cm-2 IrO2 gives a current density of 1.79 A cm-2 at 1.6 V, which is comparable to the conventional powder-type IrO2 electrode with 2.0 mg cm-2 at a temperature of 120 °C and pressure of 2.5 bar. The major factors for cell performances are rationalized in terms of overpotentials, water flow rates and thickness of diffusion layers, based on polarization behavior and ac-impedance response.

  7. Operating Range for High Temperature Borosilicate Waste Glasses: (Simulated Hanford Enveloped)

    SciTech Connect

    Mohammad, J.; Ramsey, W. G.; Toghiani, R. K.

    2003-02-24

    The following results are a part of an independent thesis study conducted at Diagnostic Instrumentation and Analysis Laboratory-Mississippi State University. A series of small-scale borosilicate glass melts from high-level waste simulant were produced with waste loadings ranging from 20% to 55% (by mass). Crushed glass was allowed to react in an aqueous environment under static conditions for 7 days. The data obtained from the chemical analysis of the leachate solutions were used to test the durability of the resulting glasses. Studies were performed to determine the qualitative effects of increasing the B2O3 content on the overall waste glass leaching behavior. Structural changes in a glass arising due to B2O3 were detected indirectly by its chemical durability, which is a strong function of composition and structure. Modeling was performed to predict glass durability quantitatively in an aqueous environment as a direct function of oxide composition.

  8. Correlation of Exhaust-Valve Temperatures with Engine Operating Conditions and Valve Design in an Air-Cooled Cylinder

    NASA Technical Reports Server (NTRS)

    Zipkin, M A; Sanders, J C

    1945-01-01

    A semiempirical equation correlating exhaust-valve temperatures with engine operating conditions and exhaust-valve design has been developed. The correlation is based on the theory correlating engine and cooling variables developed in a previous NACA report. In addition to the parameters ordinarily used in the correlating equation, a term is included in the equation that is a measure of the resistance of the complex heat-flow paths between the crown of the exhaust valve and a point on the outside surface of the cylinder head. A means for comparing exhaust valves of different designs with respect to cooling is consequently provided. The necessary empirical constants included in the equation were determined from engine investigations of a large air-cooled cylinder. Tests of several valve designs showed that the calculated and experimentally determined exhaust-valve temperatures were in good agreement.

  9. Effects of temperature and operation parameters on the galvanic corrosion of Cu coupled to Au in organic solderability preservatives process

    NASA Astrophysics Data System (ADS)

    Oh, SeKwon; Kim, YoungJun; Jung, KiMin; Kim, JongSoo; Shon, MinYoung; Kwon, HyukSang

    2017-03-01

    In this work, we quantitatively examined the effects of temperature and operation parameters such as anode (Cu) to cathode (Au) area ratio, stirring speed, and Cu ion concentration on the galvanic corrosion kinetics of Cu coupled to Au (icouple ( Cu-Au)) on print circuit board in organic solderability preservative (OSP) soft etching solution. With the increase of temperature, galvanic corrosion rate (icouple ( Cu-Au) was increased; however, the degree of galvanic corrosion rate (icouple ( Cu-Au) - icorr (Cu)) was decreased owing to the lower activation energy of Cu coupled to Au, than that of Cu alone. With the increase of area ratio (cathode/anode), stirring speed of the system, icouple ( Cu-Au) was increased by the increase of cathodic reaction kinetics. And icouple ( Cu-Au) was decreased by the increase of the Cu-ion concentration in the OSP soft etching solution.

  10. Effects of temperature and operation parameters on the galvanic corrosion of Cu coupled to Au in organic solderability preservatives process

    NASA Astrophysics Data System (ADS)

    Oh, SeKwon; Kim, YoungJun; Jung, KiMin; Kim, JongSoo; Shon, MinYoung; Kwon, HyukSang

    2017-02-01

    In this work, we quantitatively examined the effects of temperature and operation parameters such as anode (Cu) to cathode (Au) area ratio, stirring speed, and Cu ion concentration on the galvanic corrosion kinetics of Cu coupled to Au (icouple (Cu-Au)) on print circuit board in organic solderability preservative (OSP) soft etching solution. With the increase of temperature, galvanic corrosion rate (icouple (Cu-Au) was increased; however, the degree of galvanic corrosion rate (icouple (Cu-Au) - icorr (Cu)) was decreased owing to the lower activation energy of Cu coupled to Au, than that of Cu alone. With the increase of area ratio (cathode/anode), stirring speed of the system, icouple (Cu-Au) was increased by the increase of cathodic reaction kinetics. And icouple (Cu-Au) was decreased by the increase of the Cu-ion concentration in the OSP soft etching solution.

  11. Assessment of body mapping sportswear using a manikin operated in constant temperature mode and thermoregulatory model control mode

    NASA Astrophysics Data System (ADS)

    Wang, Faming; Del Ferraro, Simona; Molinaro, Vincenzo; Morrissey, Matthew; Rossi, René

    2014-09-01

    Regional sweating patterns and body surface temperature differences exist between genders. Traditional sportswear made from one material and/or one fabric structure has a limited ability to provide athletes sufficient local wear comfort. Body mapping sportswear consists of one piece of multiple knit structure fabric or of different fabric pieces that may provide athletes better wear comfort. In this study, the `modular' body mapping sportswear was designed and subsequently assessed on a `Newton' type sweating manikin that operated in both constant temperature mode and thermophysiological model control mode. The performance of the modular body mapping sportswear kit and commercial products were also compared. The results demonstrated that such a modular body mapping sportswear kit can meet multiple wear/thermal comfort requirements in various environmental conditions. All body mapping clothing (BMC) presented limited global thermophysiological benefits for the wearers. Nevertheless, BMC showed evident improvements in adjusting local body heat exchanges and local thermal sensations.

  12. Assessment of body mapping sportswear using a manikin operated in constant temperature mode and thermoregulatory model control mode.

    PubMed

    Wang, Faming; Del Ferraro, Simona; Molinaro, Vincenzo; Morrissey, Matthew; Rossi, René

    2014-09-01

    Regional sweating patterns and body surface temperature differences exist between genders. Traditional sportswear made from one material and/or one fabric structure has a limited ability to provide athletes sufficient local wear comfort. Body mapping sportswear consists of one piece of multiple knit structure fabric or of different fabric pieces that may provide athletes better wear comfort. In this study, the 'modular' body mapping sportswear was designed and subsequently assessed on a 'Newton' type sweating manikin that operated in both constant temperature mode and thermophysiological model control mode. The performance of the modular body mapping sportswear kit and commercial products were also compared. The results demonstrated that such a modular body mapping sportswear kit can meet multiple wear/thermal comfort requirements in various environmental conditions. All body mapping clothing (BMC) presented limited global thermophysiological benefits for the wearers. Nevertheless, BMC showed evident improvements in adjusting local body heat exchanges and local thermal sensations.

  13. Maximum allowable heat flux for a submerged horizontal tube bundle

    SciTech Connect

    McEligot, D.M.

    1995-08-14

    For application to industrial heating of large pools by immersed heat exchangers, the socalled maximum allowable (or {open_quotes}critical{close_quotes}) heat flux is studied for unconfined tube bundles aligned horizontally in a pool without forced flow. In general, we are considering boiling after the pool reaches its saturation temperature rather than sub-cooled pool boiling which should occur during early stages of transient operation. A combination of literature review and simple approximate analysis has been used. To date our main conclusion is that estimates of q inch chf are highly uncertain for this configuration.

  14. Performance Evaluation of Conventional Sb-based Multiquantum Well Lasers operating above 3μm at Room Temperature

    NASA Astrophysics Data System (ADS)

    Kadri, A.; Zitouni, K.; Rouillard, Y.; Christol, P.

    We present the results of a theoretical performance evaluation of conventional type I Sb-based Quinary Multiple Quantum Well Lasers operating in cw at λ>3μm at Room Temperature. In this purpose, we use a k.P band structure model to calculate the optical properties of these new Quinary Sb-based heterostructures. Our calculations show that for optimized laser structures emitting near 3.3μm, modal gain value GmodalM =50cm-1 and threshold current densities Jth = 2-3 kA/cm2 are expected. Thanks to the valence band offset enhancement, hole lifetime are shown to increase by one order of magnitude in Quinary laser with respect to Quaternary counterpart. Our results show that this kind of Quinary Sb-based type I laser structures are quite convenient for cw RT Laser operation at λ>3μm.

  15. Implications of Graphite Radiation Damage on the Neutronic, Operational, and Safety Aspects of Very High Temperature Reactors

    SciTech Connect

    Hawari, Ayman I

    2011-08-30

    In both the prismatic and pebble bed designs of Very High Temperature Reactors (VHTR), the graphite moderator is expected to reach exposure levels of 1021 to 1022 n/cm2 over the lifetime of the reactor. This exposure results in damage to the graphite structure. In this work, molecular dynamic and ab initio molecular static calculations will be used to: 1) simulate radiation damage in graphite under various irradiation and temperature conditions, 2) generate the thermal neutron scattering cross sections for damaged graphite, and 3) examine the resulting microstructure to identify damage formations that may produce the high-temperature Wigner effect. The impact of damage on the neutronic, operational and safety behavior of the reactor will be assessed using reactor physics calculations. In addition, tests will be performed on irradiated graphite samples to search for the high-temperature Wigner effect, and phonon density of states measurements will be conducted to quantify the effect on thermal neutron scattering cross sections using these samples.

  16. Submilliampere continuous-wave room-temperature lasing operation of a GaAs mushroom structure surface-emitting laser

    SciTech Connect

    Yang, Y.J.; Dziura, T.G.; Wang, S.C. ); Hsin, W.; Wang, S. Electronics Research Laboratory, University of California, Berkeley, California 94720 )

    1990-05-07

    We report a GaAs mushroom structure surface-emitting laser at 900 nm with submilliampere (0.2--0.5 mA) threshold under room-temperature cw operation for the first time. The very low threshold current was achieved on devices which consisted of a 2--4 {mu}m diameter active region formed by chemical selective etching, and sandwiched between two Al{sub 0.05}Ga{sub 0.95} As/ Al{sub 0.53}Ga{sub 0.47} As distributed Bragg reflectors of very high reflectivity (98--99%) grown by metalorganic chemical vapor deposition.

  17. Optimization of 3-junction inverted metamorphic solar cells for high-temperature and high-concentration operation

    NASA Astrophysics Data System (ADS)

    Geisz, John F.; Duda, Anna; France, Ryan M.; Friedman, Daniel J.; Garcia, Ivan; Olavarria, Waldo; Olson, Jerry M.; Steiner, Myles A.; Ward, J. Scott; Young, Michelle

    2012-10-01

    Four different band gap combinations of triple-junction inverted metamorphic solar cells are characterized as a function of temperature and concentration up to 120°C and ˜1000 suns. We demonstrate that the standard 1.82/1.40/1.00 eV combination is an excellent choice for typical operating conditions of 1000 suns and 75°C. Improved metal grids and thermal management in such a cell has achieved 42.6% efficiency at 327 suns and 40.9% at 1093 suns at 25°C.

  18. Experimental design, operation, and results of a 4 kW high temperature steam electrolysis experiment

    SciTech Connect

    Zhang, Xiaoyu; O'Brien, James E.; Tao, Greg; Zhou, Can; Housley, Gregory K.

    2015-08-06

    High temperature steam electrolysis (HTSE) is a promising technology for large-scale hydrogen production. However, research on HTSE performance above the kW level is limited. This paper presents the results of 4 kW HTSE long-term test completed in a multi-kW test facility recently developed at the Idaho National Laboratory (INL). The 4 kW HTSE unit included two solid oxide electrolysis stacks operating in parallel, each of which included 40 electrode-supported planar cells. A current density of 0.41 A/cm2 was used for the long-term operation, resulting in a hydrogen production rate about 25 slpm. A demonstration of 920 hours stable operation was achieved. The paper also includes detailed descriptions of the piping layout, steam generation and delivery system, test fixture, heat recuperation system, hot zone, instrumentation, and operating conditions. As a result, this successful demonstration of multi-kW scale HTSE unit will help to advance the technology toward near-term commercialization.

  19. Experimental design, operation, and results of a 4 kW high temperature steam electrolysis experiment

    DOE PAGES

    Zhang, Xiaoyu; O'Brien, James E.; Tao, Greg; ...

    2015-08-06

    High temperature steam electrolysis (HTSE) is a promising technology for large-scale hydrogen production. However, research on HTSE performance above the kW level is limited. This paper presents the results of 4 kW HTSE long-term test completed in a multi-kW test facility recently developed at the Idaho National Laboratory (INL). The 4 kW HTSE unit included two solid oxide electrolysis stacks operating in parallel, each of which included 40 electrode-supported planar cells. A current density of 0.41 A/cm2 was used for the long-term operation, resulting in a hydrogen production rate about 25 slpm. A demonstration of 920 hours stable operation wasmore » achieved. The paper also includes detailed descriptions of the piping layout, steam generation and delivery system, test fixture, heat recuperation system, hot zone, instrumentation, and operating conditions. As a result, this successful demonstration of multi-kW scale HTSE unit will help to advance the technology toward near-term commercialization.« less

  20. Synthesis and properties of aluminum-based composite materials for high operating temperatures

    NASA Astrophysics Data System (ADS)

    Vorozhtsov, Sergey; Khrustalyov, Anton; Kulkov, Sergey

    2016-11-01

    Aluminum-based composite materials reinforced with ceramic particles are of great practical interest due to their potentially high physical and mechanical properties. In this work, Al-Al4C3 composites are obtained by a hot-pressing method. Introduction of nanodiamonds into aluminum nanopowder in the amount 10 wt % leads to the formation of 15 wt % of aluminum carbide during hot pressing. It is found that composite materials with the diamond content of 10 wt % in the initial powder mixture have the microhardness 150 HV whilst the similarly hot-pressed aluminum powder without reinforcing particles shows a hardness of 75 HV. The mechanical properties of an Al-Al4C3 composite material at elevated test temperatures exceed those of commercial casting aluminum alloys.

  1. Design, operation, and housing of an ultrastable, low temperature, ultrahigh vacuum scanning tunneling microscope

    NASA Astrophysics Data System (ADS)

    Ferris, J. H.; Kushmerick, J. G.; Johnson, J. A.; Yoshikawa Youngquist, M. G.; Kessinger, R. B.; Kingsbury, H. F.; Weiss, P. S.

    1998-07-01

    We have designed and constructed a low temperature, ultrahigh vacuum scanning tunneling microscope (STM), taking extreme measures to isolate the microscope from acoustic, vibrational, and electronic noise. We combined a 4 K STM with line-of-sight dosing to enable one to position the crystal surface in front of an impinging molecular beam as in scattering experiments. Due to the mechanical stability of the instrument and the minimal thermal drift associated with working at 4 K we are able to locate and to image repeatedly isolated adsorbates and atomic-scale structures, such as step edges, for extended periods days. The instrument has been designed for the topographic and spectroscopic characterization of atoms and molecules on metal and semiconductor surfaces, for the investigation of the mechanism by which the STM images adsorbates on surfaces, and for inelastic electron tunneling spectroscopy of single molecules.

  2. High-Temperature (1000 F) Magnetic Thrust Bearing Test Rig Completed and Operational

    NASA Technical Reports Server (NTRS)

    Montague, Gerald T.

    2005-01-01

    Large axial loads are induced on the rolling element bearings of a gas turbine. To extend bearing life, designers use pneumatic balance pistons to reduce the axial load on the bearings. A magnetic thrust bearing could replace the balance pistons to further reduce the axial load. To investigate this option, the U.S. Army Research Laboratory, the NASA Glenn Research Center, and Texas A&M University designed and fabricated a 7-in.- diameter magnetic thrust bearing to operate at 1000 F and 30,000 rpm, with a 1000-lb load capacity. This research was funded through a NASA Space Technology Transfer Act with Allison Advance Development Company under the Ultra-Efficient Engine Technology (UEET) Intelligent Propulsion Systems Foundation Technology project.

  3. Method to Measure Total Noise Temperature of a Wireless Receiver During Operation

    NASA Technical Reports Server (NTRS)

    Young, Lawrence E. (Inventor); Turbiner, Dmitry (Inventor); Esterhuizen, Stephan X. (Inventor)

    2014-01-01

    An electromagnetic signal receiver and methods for determining the noise level and signal power in a signal of interest while the receiver is operating. In some embodiments, the signal of interest is a GPS signal. The receiver includes a noise source that provides a noise signal of known power during intervals while the signal of interest is observed. By measuring a signal-to-noise ratio for the signal of interest and the noise power in the signal of interest, the noise level and signal power of the signal of interest can be computed. Various methods of making the measurements and computing the power of the signal of interest are described. Applications of the system and method are described.

  4. Evaluation of Fairchild's Gate Drive Optocoupler, Type FOD3150, Under Wide Temperature Operation

    NASA Technical Reports Server (NTRS)

    Patterson, Richard; Hammoud, Adhad; Panko, Scott

    2010-01-01

    An optocoupler is a semiconductor device that is used to transfer a signal between different parts of a circuit that need to be electrically isolated from one another - for example, where a high voltage is to be switched with a low voltage control signal. Optocouplers often can be used in place of relays. These optocouplers utilize an infrared LED (light emitting diode) and a photodetector such as a silicon controlled rectifier or photosensitive silicon diode for the transfer of the electronic signal between components of a circuit by means of a short optical transmission channel. For maximum coupling, the wave-length responses of the LED and the detector should be very similar. In switch-mode power supply applications, optocouplers offer advantages over transformers by virtue of simpler circuit design, reduced weight, and DC coupling capability. The effects of extreme temperature exposure and thermal cycling on the performance of a commercial-off-the-shelf (COTS) optocoupler, Fairchild FOD3150, were evaluated in this work. This 1.0 A output current, high noise immunity gate drive optocoupler utilizes an aluminum gallium arsenide (AlGaAs) LED, is capable of driving most 800V/20A IGBT/MOSFETs, and is suited for fast switching in motor control inverter applications and high performance power systems. Some of the specifications of the isolator chip are listed. The device was evaluated in terms of output response, output rise (t(sub r)) and fall times (t(sub f)), and propagation delays (using a 50% level between input and output during low to high (t(sub PLH)) and high to low (t(sub PLH)) transitions). The output supply current was also obtained. These parameters were recorded at various test temperatures between -190 C and +110 C.

  5. A Simple Technique for Creating Regional Composites of Sea Surface Temperature from MODIS for Use in Operational Mesoscale NWP

    NASA Technical Reports Server (NTRS)

    Knievel, Jason C.; Rife, Daran L.; Grim, Joseph A.; Hahmann, Andrea N.; Hacker, Joshua P.; Ge, Ming; Fisher, Henry H.

    2010-01-01

    This paper describes a simple technique for creating regional, high-resolution, daytime and nighttime composites of sea surface temperature (SST) for use in operational numerical weather prediction (NWP). The composites are based on observations from NASA s Moderate Resolution Imaging Spectroradiometer (MODIS) aboard Aqua and Terra. The data used typically are available nearly in real time, are applicable anywhere on the globe, and are capable of roughly representing the diurnal cycle in SST. The composites resolution is much higher than that of many other standard SST products used for operational NWP, including the low- and high-resolution Real-Time Global (RTG) analyses. The difference in resolution is key because several studies have shown that highly resolved SSTs are important for driving the air sea interactions that shape patterns of static stability, vertical and horizontal wind shear, and divergence in the planetary boundary layer. The MODIS-based composites are compared to in situ observations from buoys and other platforms operated by the National Data Buoy Center (NDBC) off the coasts of New England, the mid-Atlantic, and Florida. Mean differences, mean absolute differences, and root-mean-square differences between the composites and the NDBC observations are all within tenths of a degree of those calculated between RTG analyses and the NDBC observations. This is true whether or not one accounts for the mean offset between the skin temperatures of the MODIS dataset and the bulk temperatures of the NDBC observations and RTG analyses. Near the coast, the MODIS-based composites tend to agree more with NDBC observations than do the RTG analyses. The opposite is true away from the coast. All of these differences in point-wise comparisons among the SST datasets are small compared to the 61.08C accuracy of the NDBC SST sensors. Because skin-temperature variations from land to water so strongly affect the development and life cycle of the sea breeze, this

  6. Lead iodide X-ray and gamma-ray spectrometers for room and high temperature operation

    SciTech Connect

    Hermon, H.; James, R.B.; Cross, E.

    1997-02-01

    In this study, we report on the results of the investigation of lead iodide material properties. The effectiveness of zone refining purification methods on the material purity is determined by ICP-MS and ICP-OES and correlated to the electrical and physical material properties. We show that this zone refining method is very efficient in removing impurities from lead iodide and we also determine the segregation coefficient for some of these impurities. Triple axis x- ray diffraction (TAD) analysis has been used to determine the crystalline perfection of the lead iodide after applying various cutting, etching, and fabrication methods. The soft lead iodide crystal was found to be damaged when cleaved by a razor blade, but by using a diamond wheel saw, followed by etching, the crystallinity of the material was improved, as observed by TAD. Low temperature photoluminescence also indicates an improvement in the material properties of the purified lead iodide. Electrical properties of lead iodide such as carrier mobility, were calculated based on carrier- phonon scattering. The results for the electrical properties were in good agreement with the experimental data.

  7. Monolithically integrated mid-infrared sensor using narrow mode operation and temperature feedback

    SciTech Connect

    Ristanic, Daniela; Schwarz, Benedikt Reininger, Peter; Detz, Hermann; Zederbauer, Tobias; Andrews, Aaron Maxwell; Schrenk, Werner; Strasser, Gottfried

    2015-01-26

    A method to improve the sensitivity and selectivity of a monolithically integrated mid-infrared sensor using a distributed feedback laser (DFB) is presented in this paper. The sensor is based on a quantum cascade laser/detector system built from the same epitaxial structure and with the same fabrication approach. The devices are connected via a dielectric-loaded surface plasmon polariton waveguide with a twofold function: it provides high light coupling efficiency and a strong interaction of the light with the environment (e.g., a surrounding fluid). The weakly coupled DFB quantum cascade laser emits narrow mode light with a FWHM of 2 cm{sup −1} at 1586 cm{sup −1}. The room temperature laser threshold current density is 3 kA∕cm{sup 2} and a pulsed output power of around 200 mW was measured. With the superior laser noise performance, due to narrow mode emission and the compensation of thermal fluctuations, the lower limit of detection was expanded by one order of magnitude to the 10 ppm range.

  8. Construction and Operation of an Internal Coil Device, RT-1, with a High-Temperature Superconductor

    NASA Astrophysics Data System (ADS)

    Ogawa, Yuichi; Yoshida, Zensho; Morikawa, Junji; Saito, Haruhiko; Watanabe, Sho; Yano, Yoshihisa; Mizumaki, Shoichi; Tosaka, Taizo

    An internal coil device called Ring Trap-1 (RT-1) has been constructed to explore an innovative concept for a high-beta plasma based on a new relaxation theory. A high-temperature superconductor (HTS) Bi-2223 tape is employed for the internal coil of RT-1. The coil is cooled to 20 K with helium gas supplied by G-M refrigerators, and charged to a magnetomotive force of 250 kA using an external power supply. For these cooling and charging methods, we have developed several innovative techniques such as a demountable transfer tube system, persistent current switch, detachable electrode, and others. In addition, we have paid much attention to the deterioration of the HTS tape during the fabrication of the internal coil. As a result, we have demonstrated that the decay of the persistent current of the internal coil is ˜1% during 8 h. The internal coil is lifted with a levitation coil located at the upper region of the vacuum vessel. The coil position monitored with laser sensors is feedback controlled through the regulation of the levitation coil current. Stable levitation for a few hours has been demonstrated for various plasma experiments.

  9. Test Plan for Long-Term Operation of a Ten-Cell High Temperature Electrolysis Stack

    SciTech Connect

    James E. O'Brien; Carl M. Stoots; J. Stephen Herring

    2008-07-01

    This document defines a test plan for a long-term (2500 Hour) test of a ten-cell high-temperature electrolysis stack to be performed at INL during FY09 under the Nuclear Hydrogen Initiative. This test was originally planned for FY08, but was removed from our work scope as a result of the severe budget cuts in the FY08 NHI Program. The purpose of this test is to evaluate stack performance degradation over a relatively long time period and to attempt to identify some of the degradation mechanisms via post-test examination. This test will be performed using a planar ten-cell Ceramatec stack, with each cell having dimensions of 10 cm × 10 cm. The specific makeup of the stack will be based on the results of a series of shorter duration ten-cell stack tests being performed during FY08, funded by NGNP. This series of tests was aimed at evaluating stack performance with different interconnect materials and coatings and with or without brazed edge rails. The best performing stack from the FY08 series, in which five different interconnect/coating/edge rail combinations were tested, will be selected for the FY09 long-term test described herein.

  10. Iron overload detection in rats by means of a susceptometer operating at room temperature

    NASA Astrophysics Data System (ADS)

    Marinelli, M.; Gianesin, B.; Avignolo, C.; Minganti, V.; Parodi, S.

    2008-12-01

    Biosusceptometry is a non-invasive procedure for determination of iron overload in a human body; it is essentially an assessment of the diamagnetic (water) and paramagnetic (iron) properties of tissues. We measured in vivo iron overload in the liver region of 12 rats by a room temperature susceptometer. The rats had been injected with sub-toxic doses of iron dextran. A quantitative relationship has been observed between the measurements and the number of treatments. The assessment of iron overload requires evaluating the magnetic signal corresponding to the same rat ideally without the overload. This background value was extrapolated on the basis of the signal measured in control rats versus body weight (R2 = 0.73). The mean iron overload values for the treated rats, obtained after each iron injection, were significantly different from the means of the corresponding control rats (p < 0.01). The in vivo measurements have been complemented by chemical analysis on excised livers and other organs (R2 = 0.89). The magnetic moment of iron atoms in liver tissues was measured to be 3.6 Bohr magneton. Evaluation of the background signal is the limit to the measure; the error corresponds to about 30 mg (1 SD) of iron while the instrument sensitivity is more than a factor of 10 better.

  11. 40 CFR 35.2025 - Allowance and advance of allowance.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... facilities planning and design of the project and Step 7 agreements will include an allowance for facility planning in accordance with appendix B of this subpart. (b) Advance of allowance to potential grant... grant applicants for facilities planning and project design. (2) The State may request that the right...

  12. Polymer Nanodot-Hybridized Alkyl Silicon Oxide Nanostructures for Organic Memory Transistors with Outstanding High-Temperature Operation Stability

    PubMed Central

    Lee, Chulyeon; Seo, Jooyeok; Kim, Jeongnam; Jeong, Jaehoon; Han, Hyemi; Kim, Hwajeong; Kim, Youngkyoo

    2016-01-01

    Organic memory devices (OMDs) are becoming more important as a core component in flexible electronics era because of their huge potentials for ultrathin, lightweight and flexible plastic memory modules. In particular, transistor-type OMDs (TOMDs) have been gradually spotlighted due to their structural advantages possessing both memory and driving functions in single devices. Although a variety of TOMDs have been developed by introducing various materials, less attention has been paid to the stable operation at high temperatures. Here we demonstrate that the polymer nanodot-embedded alkyl silicon oxide (ASiO) hybrid materials, which are prepared by sol-gel and thermal cross-linking reactions between poly(4-vinylphenol) (PVP) and vinyltriethoxysilane, can deliver low-voltage (1~5 V) TOMDs with outstanding operation stability (>4700 cycles) at high temperatures (150 °C). The efficient low-voltage memory function is enabled by the embedded PVP nanodots with particular lattice nanostructures, while the high thermal stability is achieved by the cross-linked ASiO network structures. PMID:27703187

  13. Anomalous effects of temperature and UV illumination on the operation of AlGaN/GaN MODFET

    NASA Astrophysics Data System (ADS)

    Valizadeh, Pouya; Alekseev, Egor; Pavlidis, Dimitris; Yun, Feng; Morkoç, Hadis

    2006-02-01

    The impact of high temperature rapid thermal annealing (RTA) on the mode of operation of AlGaN/GaN modulation doped field effect transistors (MODFETs) is reported. It is observed that annealing at high temperatures is capable of turning the normally depletion-mode (D-mode) characteristics of an AlGaN/GaN MODFET, towards that of an enhancement-mode (E-mode). This change is shown to be partly reversible through UV illumination. These results support the arguments on the extensive role of deep surface states on the operation of AlGaN/GaN MODFETs. According to this variation of characteristics, fabrication and characterization of close to E-mode AlGaN/GaN MODFETs are reported, using MBE grown material on sapphire. The devices demonstrate maximum extrinsic gate transconductance of 180 mS/mm. Unity current gain cutoff frequency ( fT) of 5 GHz and maximum oscillation frequency ( fmax) of 14 GHz were measured.

  14. Polymer Nanodot-Hybridized Alkyl Silicon Oxide Nanostructures for Organic Memory Transistors with Outstanding High-Temperature Operation Stability

    NASA Astrophysics Data System (ADS)

    Lee, Chulyeon; Seo, Jooyeok; Kim, Jeongnam; Jeong, Jaehoon; Han, Hyemi; Kim, Hwajeong; Kim, Youngkyoo

    2016-10-01

    Organic memory devices (OMDs) are becoming more important as a core component in flexible electronics era because of their huge potentials for ultrathin, lightweight and flexible plastic memory modules. In particular, transistor-type OMDs (TOMDs) have been gradually spotlighted due to their structural advantages possessing both memory and driving functions in single devices. Although a variety of TOMDs have been developed by introducing various materials, less attention has been paid to the stable operation at high temperatures. Here we demonstrate that the polymer nanodot-embedded alkyl silicon oxide (ASiO) hybrid materials, which are prepared by sol-gel and thermal cross-linking reactions between poly(4-vinylphenol) (PVP) and vinyltriethoxysilane, can deliver low-voltage (1~5 V) TOMDs with outstanding operation stability (>4700 cycles) at high temperatures (150 °C). The efficient low-voltage memory function is enabled by the embedded PVP nanodots with particular lattice nanostructures, while the high thermal stability is achieved by the cross-linked ASiO network structures.

  15. Polymer Nanodot-Hybridized Alkyl Silicon Oxide Nanostructures for Organic Memory Transistors with Outstanding High-Temperature Operation Stability.

    PubMed

    Lee, Chulyeon; Seo, Jooyeok; Kim, Jeongnam; Jeong, Jaehoon; Han, Hyemi; Kim, Hwajeong; Kim, Youngkyoo

    2016-10-05

    Organic memory devices (OMDs) are becoming more important as a core component in flexible electronics era because of their huge potentials for ultrathin, lightweight and flexible plastic memory modules. In particular, transistor-type OMDs (TOMDs) have been gradually spotlighted due to their structural advantages possessing both memory and driving functions in single devices. Although a variety of TOMDs have been developed by introducing various materials, less attention has been paid to the stable operation at high temperatures. Here we demonstrate that the polymer nanodot-embedded alkyl silicon oxide (ASiO) hybrid materials, which are prepared by sol-gel and thermal cross-linking reactions between poly(4-vinylphenol) (PVP) and vinyltriethoxysilane, can deliver low-voltage (1~5 V) TOMDs with outstanding operation stability (>4700 cycles) at high temperatures (150 °C). The efficient low-voltage memory function is enabled by the embedded PVP nanodots with particular lattice nanostructures, while the high thermal stability is achieved by the cross-linked ASiO network structures.

  16. The measurement of phase equilibria for process streams at operating temperatures and the implications for the CRE liquefaction project

    SciTech Connect

    Waller, A.; Walton, S.T.

    1994-12-31

    CRE operates the Liquid Solvent Extraction process at its pilot plant in North Wales, UK. The process involves feeding pulverised coal, slurried with a solvent, to a digester in which much of the coal is dissolved. Filtration removes residual solids. The coal solution is fed to an ebulliating bed hydrocracker, together with hydrogen at 200 bar at 425{degrees}C. The catalytic reaction adds hydrogen to the coal solution which is distilled to recover solvent and yield a product. The vessels and pipework are externally heated to ensure that liquids can be pumped but temperatures arc not high enough to initiate regressive reactions with consequent formation of carbonaceous solids. However, coal derived liquids are complex mixtures of hydrocarbons which are not soluble in all proportions at all temperatures. Precipitation may occur, leading to blockages in process lines and equipment with subsequent interruption to plant operation. Coal liquids can be regarded simply as a three component system comprising pitch (material with a boiling point >450{degrees}C), saturated hydrocarbon (saturates) having a boiling point <450{degrees}C and distillate solvent, the remainder of the material boiling below 450{degrees}C. Coal solution, of which LSE recycle solvent is a particular case, is a mixture of these three components. A study was undertaken to examine the quantity and nature of precipitates formed from coal solutions of various compositions, with a view to preventing plant shutdowns caused by blocked lines.

  17. Study on the reversible capacity loss of layered oxide cathode during low-temperature operation

    NASA Astrophysics Data System (ADS)

    Li, Yiyang; Qian, Kun; He, Yan-Bing; Kaneti, Yusuf Valentino; Liu, Dongqing; Luo, Dan; Li, Hai; Li, Baohua; Kang, Feiyu

    2017-02-01

    In this study, commercial Li(Ni1/3Co1/3Mn1/3)O2/graphite (NCM/C) lithium-ion batteries were cycled at -10 °C under different current rates ranging from 0.2 C to 1C. Electrochemical measurements and post-mortem analysis were performed to identify the root causes of the degradation in the electrochemical performance of the cells. The results reveal that apart from the increase of lithium plating on the anode, there is a considerable and abnormal capacity loss on the NCM cathode with the increase in current rate. The different degradation mechanisms including the loss of lithium inventory (LLI) and the specific capacity loss of NCM material (LAM) during cycling at -10 °C were analyzed quantitatively. It is shown that the evolution trend of LLI with the increase in current rate (8.6%, 35.0%, 55.8% for 0.2 C, 0.5 C and 1 C respectively) corresponds closely to that of the capacity loss of the full-cells (8.6%, 45.5%, 63.6% for 0.2 C, 0.5 C and 1 C, respectively), which is different to the trend of LAM (7.2%, 8.8%, 22.3% for 0.2 C, 0.5 C and 1 C, respectively). Further analysis by XRD and HR-TEM clearly indicates that the crystallinity of the hexagonal layered structure of NCM was greatly impaired after low-temperature cycling at -10 °C, and spinel phase can be observed among the layered structure.

  18. Additive for Low-Temperature Operation of Li-(CF)n Cells

    NASA Technical Reports Server (NTRS)

    West, William; Whitacre, Jay

    2009-01-01

    Some progress has been reported in continuing research on the use of anion-receptor compounds as electrolyte additives to increase the sustainable rates of discharge and, hence, the discharge capacities, of lithium-poly(carbon monofluoride) [Li-(CF)n, where n >1] primary electrochemical power cells. Some results of this research at a prior stage were summarized in Increasing Discharge Capacities of Li(CF)n Cells (NPO-42346), NASA Tech Briefs, Vol. 32, No. 2 (February 2008), page 37. A major difference between the present and previously reported results is that now there is some additional focus on improving performance at temperatures from ambient down to as low as 40 C. To recapitulate from the cited prior article: During the discharge of a Li-(CF)n cell, one of the electrochemical reactions causes LiF to precipitate at the cathode. LiF is almost completely insoluble in most non-aqueous solvents, including those used in the electrolyte solutions of Li- (CF)n cells. LiF is electrochemically inactive and can block the desired transport of electrons at the cathode, and, hence, the precipitation of LiF can form an ever-thickening film on the cathode that limits the rate of discharge. An anion-receptor electrolyte additive helps to increase the discharge capacity in two ways: It renders LiF somewhat soluble in the non-aqueous electrolyte solution, thereby delaying precipitation until a high concentration of LiF in solution has been reached. When precipitation occurs, it promotes the formation of large LiF grains that do not conformally coat the cathode. The net effect is to reduce the blockage caused by precipitation of LiF, thereby maintaining a greater degree of access of electrolyte to the cathode and greater electronic conductivity.

  19. 42 CFR 417.534 - Allowable costs.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... typical “provider” costs, and costs (such as marketing, enrollment, membership, and operation of the HMO... principles applicable to provider costs, as set forth in § 417.536. (2) The allowability of other costs is determined in accordance with principles set forth in §§ 417.538 through 417.550. (3) Costs for...

  20. 29 CFR 15.41 - Allowable claims.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... Arising Out of the Operation of the Job Corps § 15.41 Allowable claims. (a)(1) A claim for damage to persons or property arising out of an act or omission of a student enrolled in the Job Corps may...

  1. Enhancing Nitrification at Low Temperature with Zeolite in a Mining Operations Retention Pond

    PubMed Central

    Miazga-Rodriguez, Misha; Han, Sukkyun; Yakiwchuk, Brian; Wei, Kai; English, Colleen; Bourn, Steven; Bohnert, Seth; Stein, Lisa Y.

    2012-01-01

    Ammonium nitrate explosives are used in mining operations at Diavik Diamond Mines Inc. in the Northwest Territories, Canada. Residual nitrogen is washed into the mine pit and piped to a nearby retention pond where its removal is accomplished by microbial activity prior to a final water treatment step and release into the sub-Arctic lake, Lac de Gras. Microbial removal of ammonium in the retention pond is rapid during the brief ice-free summer, but often slows under ice cover that persists up to 9 months of the year. The aluminosilicate mineral zeolite was tested as an additive to retention pond water to increase rates of ammonium removal at 4°C. Water samples were collected across the length of the retention pond monthly over a year. The structure of the microbial community (bacteria, archaea, and eukarya), as determined by denaturing gradient gel electrophoresis of PCR-amplified small subunit ribosomal RNA genes, was more stable during cold months than during July–September, when there was a marked phytoplankton bloom. Of the ammonia-oxidizing community, only bacterial amoA genes were consistently detected. Zeolite (10 g) was added to retention pond water (100 mL) amended with 5 mM ammonium and incubated at 12°C to encourage development of a nitrifying biofilm. The biofilm community was composed of different amoA phylotypes from those identified in gene clone libraries of native water samples. Zeolite biofilm was added to fresh water samples collected at different times of the year, resulting in a significant increase in laboratory measurements of potential nitrification activity at 4°C. A significant positive correlation between the amount of zeolite biofilm and potential nitrification activity was observed; rates were unaffected in incubations containing 1–20 mM ammonium. Addition of zeolite to retention ponds in cold environments could effectively increase nitrification rates year-round by concentrating active nitrifying biomass. PMID:22866052

  2. Impact of contact resistance on the electrical properties of MoS2 transistors at practical operating temperatures

    PubMed Central

    Fisichella, Gabriele; Piazza, Aurora; Di Franco, Salvatore; Greco, Giuseppe; Agnello, Simonpietro; Roccaforte, Fabrizio

    2017-01-01

    Molybdenum disulphide (MoS2) is currently regarded as a promising material for the next generation of electronic and optoelectronic devices. However, several issues need to be addressed to fully exploit its potential for field effect transistor (FET) applications. In this context, the contact resistance, R C, associated with the Schottky barrier between source/drain metals and MoS2 currently represents one of the main limiting factors for suitable device performance. Furthermore, to gain a deeper understanding of MoS2 FETs under practical operating conditions, it is necessary to investigate the temperature dependence of the main electrical parameters, such as the field effect mobility (μ) and the threshold voltage (V th). This paper reports a detailed electrical characterization of back-gated multilayer MoS2 transistors with Ni source/drain contacts at temperatures from T = 298 to 373 K, i.e., the expected range for transistor operation in circuits/systems, considering heating effects due to inefficient power dissipation. From the analysis of the transfer characteristics (I D−V G) in the subthreshold regime, the Schottky barrier height (ΦB ≈ 0.18 eV) associated with the Ni/MoS2 contact was evaluated. The resulting contact resistance in the on-state (electron accumulation in the channel) was also determined and it was found to increase with T as R C proportional to T 3.1. The contribution of R C to the extraction of μ and V th was evaluated, showing a more than 10% underestimation of μ when the effect of R C is neglected, whereas the effect on V th is less significant. The temperature dependence of μ and V th was also investigated. A decrease of μ proportional to 1/T α with α = 1.4 ± 0.3 was found, indicating scattering by optical phonons as the main limiting mechanism for mobility above room temperature. The value of V th showed a large negative shift (about 6 V) increasing the temperature from 298 to 373 K, which was explained in terms of electron

  3. Constant temperature molecular dynamics of a protein in water by high-order decomposition of the Liouville operator

    NASA Astrophysics Data System (ADS)

    Ishida, Hisashi; Kidera, Akinori

    1998-08-01

    Among algorithms that are used to solve the equations of motion, the symplectic integrator (SI) has the advantage of conserving the phase space volume and ensuring a stable simulation. However, incorporating the explicit formula of the SI in a molecular simulation is feasible only for the systems whose Hamiltonian is described by K(p)+V(q), where the kinetic energy K and the potential energy V depend only on momenta p and coordinates q, respectively. Due to this limitation, explicit SI integrators cannot directly be applied to the Nosé-Hoover equations of motion for the constant temperature molecular dynamics (MD) simulation. In this article, by applying the formula of the decomposition of the exponential Liouville operator to the Nosé-Hoover equations, we have obtained a series of integrators for the constant temperature simulation which have the correct form of the Jacobian of the Nosé-Hoover equations. The systems examined here are liquid water and a protein in water. From the results of the constant temperature simulations, where several variations of the integrators were employed, we show that a combination of the Suzuki's second order formula and the fourth order symplectic integrator of Calvo and Sanz-Serna generates a trajectory of much higher accuracy than the nonsymplectic Gear predictor-corrector method for a given amount of CPU time.

  4. Advantages of laser-acoustical leak testing for construction and operation of low-temperature installations and superconducting experiments

    NASA Astrophysics Data System (ADS)

    Herz, W.

    2002-09-01

    At the Institute of Technical Physics of the Research Center Karlsruhe, superconducting magnets for nuclear fusion applications have been tested in the vacuum tank TOSKA for more than 20 years. A crucial test parameter of the magnet coils (mass up to 120 metric tons) as well as of the peripheral components, such as current leads (up to 80 kA), helium refrigerators (2 kW), and low-temperature transfer lines (length approx200 m), is their vacuum tightness at operating conditions (minimum temperature approx2 K, maximum refrigerant pressure 25 bar). Because the final tests at cryotemperature are costly and time consuming, intermediate tests at room temperature have already been performed at the stages of manufacturing, certification, and assembling, and prior to cooldown. So far, these tightness tests have been performed with probe gas helium employing a conventional mass spectrometer leak detector, whereby the smallest detectable leakage is limited by the He partial pressure in the surrounding air. Therefore, a new technique of leak measurement was investigated using the probe gas sulfur hexafluoride SF6, which does not occur in natural air, and which can be sensitively detected by a laser-acoustical leak detector. The obtained experimental results reveal the substantial advantages of the new method with respect to detection sensitivity, testing expenditure, and costs. The results can be transferred to tightness tests in other fields of technology. copyright 2002 American Vacuum Society.

  5. A new sensor for ammonia based on cyanidin-sensitized titanium dioxide film operating at room temperature.

    PubMed

    Huang, Xiao-wei; Zou, Xiao-bo; Shi, Ji-yong; Zhao, Jie-wen; Li, Yanxiao; Hao, Limin; Zhang, Jianchun

    2013-07-17

    Design and fabrication of an ammonia sensor operating at room temperature based on pigment-sensitized TiO2 films was described. TiO2 was prepared by sol-gel method and deposited on glass slides containing gold electrodes. Then, the film immersed in a 2.5×10(-4)M ethanol solution of cyanidin to absorb the pigment. The hybrid organic-inorganic formed film here can detect ammonia reversibly at room temperature. The relative change resistance of the films at a potential difference of 1.5V is determined when the films are exposed to atmospheres containing ammonia vapors with concentrations over the range 10-50 ppm. The relative change resistance, S, of the films increased almost linearly with increasing concentrations of ammonia (r=0.92). The response time to increasing concentrations of the ammonia is about 180-220 s, and the corresponding values for decreasing concentrations 240-270 s. At low humidity, ammonia could be ionized by the cyanidin on the TiO2 film and thereby decrease in the proton concentration at the surface. Consequently, more positively charged holes at the surface of the TiO2 have to be extracted to neutralize the adsorbed cyanidin and water film. The resistance response to ammonia of the sensors was nearly independent on temperature from 10 to 50°C. These results are not actually as good as those reported in the literature, but this preliminary work proposes simpler and cheaper processes to realize NH3 sensor for room temperature applications.

  6. Room temperature operating InAsSb-based photovoltaic infrared sensors grown by metalorganic vapor phase epitaxy

    NASA Astrophysics Data System (ADS)

    Hasegawa, Ryosuke; Yoshikawa, Akira; Morishita, Tomohiro; Moriyasu, Yoshitaka; Nagase, Kazuhiro; Kuze, Naohiro

    2017-04-01

    We have developed InAsxSb1-x-based photovoltaic infrared sensors (PVS) for room temperature operation by metalorganic vapor phase epitaxy (MOVPE). To obtain high performance, we improved the crystallinity of the InAs0.12Sb0.88 absorber layer and utilized a Ga0.33In0.67Sb electron barrier layer. An investigation of InAs0.12Sb0.88 growth conditions using a high-quality InSb buffer layer showed that we were able to obtain the smallest full-width at half-maximum (FWHM) of the X-ray diffraction omega rocking curve, 560 arcsec, for a growth temperature of 520°C for a 1 μm thick layer. Moreover, we successfully grew a Ga0.33In0.67Sb barrier layer coherently on an InAs0.12Sb0.88 absorber layer, which is the first report of GayIn1-ySb growth on Sb-rich InAsxSb1-x. An InAsxSb1-x PVS with a responsivity at wavelengths of 8-12 μm was obtained, and estimated detectivity peak at room temperature was approximately 7×107 cm Hz1/2 W-1, which is 1.3 times higher than without a Ga0.33In0.67Sb electron barrier. These results demonstrate that our InAsxSb1-x PVS is a promising device for the 8-12 μm wavelength range at room temperature.

  7. Preliminary Investigation of Molybdenum Disulfide-air-mist Lubrication for Roller Bearings Operating to DN Values of 1 x 10(exp 6) and Ball Bearings Operating to Temperatures of 1000 F

    NASA Technical Reports Server (NTRS)

    Macks, E F; Nemeth, Z N; Anderson, W J

    1951-01-01

    The effectiveness of molybdenum disulfide MoS2 as a bearing lubricant was determined at high temperature and at high speeds. A 1-inch-bore ball bearing operated at temperatures to 1000 F, a speed of 1725 rpm, and a thrust load of 20 pounds when lubricated only with MoS2-air mist. A 75-millimeter-bore cageless roller bearing, provided with a MoS2-syrup coating before operation, operated at DN values to 1 x 10(exp 6) with a load of 368 pounds.

  8. Low threshold laser operation at room temperature in GaAs/(Al,Ga)As structures grown directly on (100)Si

    SciTech Connect

    Fischer, R.; Kopp, W.; Morkoc, H.; Pion, M.; Specht, A.; Burkhart, G.; Appelman, H.; McGougan, D.; Rice, R.

    1986-05-19

    We report the room-temperature pulsed operation of GaAs/(Al,Ga)As double heterojunction laser structures grown directly on (100)Si. Current thresholds of as low as 170 mA in 10-..mu..m-wide stripe lasers have been achieved at 280 K. Power output as high as 44 mW per facet was also obtained. Assuming no current spreading, the corresponding current threshold density is 6.9 kA/cm/sup 2/. Slope efficiencies and T/sub 0/ values of 0.18 W/A and 165 K, respectively, have also been obtained. These results are directly attributable to the reduction of dislocations by choosing growth conditions and step density on the surface.

  9. Failure Mechanisms and Color Stability in Light-Emitting Diodes during Operation in High- Temperature Environments in Presence of Contamination

    SciTech Connect

    Lall, Pradeep; Zhang, Hao; Davis, J Lynn

    2015-05-26

    The energy efficiency of light-emitting diode (LED) technology compared to incandescent light bulbs has triggered an increased focus on solid state luminaries for a variety of lighting applications. Solid-state lighting (SSL) utilizes LEDs, for illumination through the process of electroluminescence instead of heating a wire filament as seen with traditional lighting. The fundamental differences in the construction of LED and the incandescent lamp results in different failure modes including lumen degradation, chromaticity shift and drift in the correlated color temperature. The use of LED-based products for safety-critical and harsh environment applications necessitates the characterization of the failure mechanisms and modes. In this paper, failure mechanisms and color stability has been studied for commercially available vertical structured thin film LED (VLED) under harsh environment conditions with and without the presence of contaminants. The VLED used for the study was mounted on a ceramic starboard in order to connect it to the current source. Contamination sources studied include operation in the vicinity of vulcanized rubber and adhesive epoxies in the presence of temperature and humidity. Performance of the VLEDs has been quantified using the measured luminous flux and color shift of the VLEDs subjected to both thermal and humidity stresses under a forward current bias of 350 mA. Results indicate that contamination can result in pre-mature luminous flux degradation and color shift in LEDs.

  10. Single Event Transient Analysis of an SOI Operational Amplifier for Use in Low-Temperature Martian Exploration

    NASA Technical Reports Server (NTRS)

    Laird, Jamie S.; Scheik, Leif; Vizkelethy, Gyorgy; Mojarradi, Mohammad M; Chen, Yuan; Miyahira, Tetsuo; Blalock, Benjamin; Greenwell, Robert; Doyle, Barney

    2006-01-01

    The next generation of Martian rover#s to be launched by JPL are to examine polar regions where temperatures are extremely low and the absence of an earth-like atmosphere results in high levels of cosmic radiation at ground level. Cosmic rays lead to a plethora of radiation effects including Single Event Transients (SET) which can severely degrade microelectronic functionality. As such, a radiation-hardened, temperature compensated CMOS Single-On-Insulator (SOI) Operational Amplifier has been designed for JPL by the University of Tennessee and fabricated by Honeywell using the SOI V process. SOI technology has been shownto be far less sensitive to transient effects than both bulk and epilayer Si. Broad beam heavy-ion tests at the University of Texas A&M using Kr and Xebeams of energy 25MeV/amu were performed to ascertain the duration and severity of the SET for the op-amp configured for a low and high gain application. However, some ambiguity regarding the location of transient formation required the use of a focused MeV ion microbeam. A 36MeV O6(+) microbeam. the Sandia National Laboratory (SNL) was used to image and verify regions of particular concern. This is a viewgraph presentation

  11. Wearable system-on-a-chip radiometer for remote temperature sensing and its application to the safeguard of emergency operators.

    PubMed

    Fonte, A; Alimenti, F; Zito, D; Neri, B; De Rossi, D; Lanatà, A; Tognetti, A

    2007-01-01

    The remote sensing and the detection of events that may represent a danger for human beings have become more and more important thanks to the latest advances of the technology. A microwave radiometer is a sensor capable to detect a fire or an abnormal increase of the internal temperature of the human body (hyperthermia), or an onset of a cancer, or even meteorological phenomena (forest fires, pollution release, ice formation on road pavement). In this paper, the overview of a wearable low-cost low-power system-on-a-chip (SoaC) 13 GHz passive microwave radiometer in CMOS 90 nm technology is presented. In particular, we focused on its application to the fire detection for civil safeguard. In detail, this sensor has been thought to be inserted into the fireman jacket in order to help the fireman in the detection of a hidden fire behind a door or a wall. The simulation results obtained by Ptolemy system simulation have confirmed the feasibility of such a SoaC microwave radiometer in a low-cost standard silicon technology for temperature remote sensing and, in particular, for its application to the safeguard of emergency operators.

  12. Material characterisation and preliminary mechanical design for the HL-LHC shielded beam screens operating at cryogenic temperatures.

    NASA Astrophysics Data System (ADS)

    Garion, C.; Dufay-Chanat, L.; Koettig, T.; Machiocha, W.; Morrone, M.

    2015-12-01

    The High Luminosity LHC project (HL-LHC) aims at increasing the luminosity (rate of collisions) in the Large Hadron Collider (LHC) experiments by a factor of 10 beyond the original design value (from 300 to 3000 fb-1). It relies on new superconducting magnets, installed close to the interaction points, equipped with new beam screen. This component has to ensure the vacuum performance together with shielding the cold mass from physics debris and screening the cold bore cryogenic system from beam induced heating. The beam screen operates in the range 40-60 K whereas the magnet cold bore temperature is 1.9 K. A tungsten-based material is used to absorb the energy of particles. In this paper, measurements of the mechanical and physical properties of such tungsten material are shown at room and cryogenic temperature. In addition, the design and the thermal mechanical behaviour of the beam screen assembly are presented also. They include the heat transfer from the tungsten absorbers to the cooling pipes and the supporting system that has to minimise the heat inleak into the cold mass. The behaviour during a magnet quench is also presented.

  13. Modeling of temperature and turbidity in a natural lake and a reservoir connected by pumped-storage operations

    NASA Astrophysics Data System (ADS)

    Bonalumi, Matteo; Anselmetti, Flavio S.; Wüest, Alfred; Schmid, Martin

    2012-08-01

    Pumped-storage (PS) systems are used to store electric energy as potential energy for release during peak demand. We investigate the impacts of a planned 1000 MW PS scheme connecting Lago Bianco with Lago di Poschiavo (Switzerland) on temperature and particle mass concentration in both basins. The upper (turbid) basin is a reservoir receiving large amounts of fine particles from the partially glaciated watershed, while the lower basin is a much clearer natural lake. Stratification, temperature and particle concentrations in the two basins were simulated with and without PS for four different hydrological conditions and 27 years of meteorological forcing using the software CE-QUAL-W2. The simulations showed that the PS operations lead to an increase in temperature in both basins during most of the year. The increase is most pronounced (up to 4°C) in the upper hypolimnion of the natural lake toward the end of summer stratification and is partially due to frictional losses in the penstocks, pumps and turbines. The remainder of the warming is from intense coupling to the atmosphere while water resides in the shallower upper reservoir. These impacts are most pronounced during warm and dry years, when the upper reservoir is strongly heated and the effects are least concealed by floods. The exchange of water between the two basins relocates particles from the upper reservoir to the lower lake, where they accumulate during summer in the upper hypolimnion (10 to 20 mg L-1) but also to some extent decrease light availability in the trophic surface layer.

  14. Improved Wide Operating Temperature Range of LiNiCoAiO2-based Li-ion Cells with Methyl Propionate-based Electrolytes

    NASA Technical Reports Server (NTRS)

    Smart, Marshall C.; Tomcsi, Michael R.; Hwang, C.; Whitcanack, L. D.; Bugga, Ratnakumar V.; Nagata, Mikito; Visco, Vince; Tsukamoto, Hisashi

    2012-01-01

    Demonstration of wide operating temperature range Li-ion electrolytes Methyl propionate-based wide operating temperature range electrolytes were demonstrated to provide dramatic improvement of the low temperature capability of Quallion prototype Li-ion cells (MCMB-LiNiCoAlO2). Some formulations were observed to deliver over 60% of the room temperature capacity using a 5C rate at - 40oC !! Represents over a 4-fold improvement over the baseline electrolyte system. Demonstrated operational capability of a number of systems over a wide temperature range (-40 to +70 C) Demonstrated reasonably good long term cycle life performance at high temperature (i.e., at +40deg and +50 C) A number of formulations containing electrolytes additives (i.e., FEC, VC, LiBOB, and lithium oxalate) have been shown to have enhanced lithium kinetics at low temperature and promising high temperature resilience. Demonstrated good performance in larger capacity (12 Ah) Quallion Li-ion cells with methyl propionate-based electrolytes. Current efforts focused upon performing life studies and the impact upon low temperature capability.

  15. Effects of dam operation on the endangered Júcar nase, Parachondrostoma arrigonis, related to mesohabitats, microhabitat availability and water temperature regime, in the river Cabriel (Spain)

    NASA Astrophysics Data System (ADS)

    Martinez-Capel, Francisco; Costa, Rui; Muñoz-Mas, Rafael; Diego Alcaraz-Hernandez, Juan; Hernandez-Mascarell, Aina

    2010-05-01

    The presence of large dams affects habitat availability, often regarded as the primary factor that limits population and community recovery in rivers. Physical habitat is often targeted in restoration, but there is often a paucity of useful information. Habitat degradation has reduced the complexity and connectivity of the Mediterranean streams in Spain. These changes have diminished the historical range of the endangered Júcar nase, Parachondrostoma arrigonis (Steindachner, 1866), isolated the populations of this species, and probably contributed to its risk of extinction. In the Júcar River basin (Spain), where this fish is endemic, the populations are mainly restricted to the river Cabriel, which is fragmented in two segments by the large dam of Contreras. In this river, 3 main lines of research were developed from 2006 to 2008, i.e., microhabitat suitability, mesohabitat suitability, and water temperature, in order to relate such kind of variables with the flow regime. The main goal of the research project, funded by the Spanish Ministry of Environment, was to detect the main reasons of the species decline, and to propose dam operation improvements to contribute to the recovery of the species. The flow and water temperature regimes were also studied in the river Cabriel, upstream and downstream the large dam of Contreras. During the three years of study, below the dam it was observed a small and not significant variation in the proportions of slow and fast habitats; the regulated flow regime was pointed out as the main reason of such variations. At the microhabitat scale, optimal ranges for average depth and velocity were defined; these data allowed us to develop an estimation of weighted useable area under natural and regulated conditions. The Júcar nase were found majorly at depths no greater than 1,15 meters with slow water velocities. It was possible to observe a clear alteration of the flow and water temperature regime below the dam, due to the cold

  16. 49 CFR 174.86 - Maximum allowable operating speed.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 174.86 Transportation Other Regulations Relating to Transportation PIPELINE AND HAZARDOUS MATERIALS SAFETY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION HAZARDOUS MATERIALS REGULATIONS CARRIAGE BY RAIL Handling of Placarded Rail Cars, Transport Vehicles and Freight Containers § 174.86 Maximum...

  17. 49 CFR 174.86 - Maximum allowable operating speed.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 174.86 Transportation Other Regulations Relating to Transportation PIPELINE AND HAZARDOUS MATERIALS SAFETY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION HAZARDOUS MATERIALS REGULATIONS CARRIAGE BY RAIL Handling of Placarded Rail Cars, Transport Vehicles and Freight Containers § 174.86 Maximum...

  18. High 400 °C operation temperature blue spectrum concentration solar junction in GaInN/GaN

    SciTech Connect

    Zhao, Liang; Detchprohm, Theeradetch; Wetzel, Christian

    2014-12-15

    Transparent wide gap junctions suitable as high temperature, high flux topping cells have been achieved in GaInN/GaN by metal-organic vapor phase epitaxy. In structures of 25 quantum wells (QWs) under AM1.5G illumination, an open circuit voltage of 2.1 V is achieved. Of the photons absorbed in the limited spectral range of <450 nm, 64.2% are converted to electrons collected at the contacts under zero bias. At a fill factor of 45%, they account for a power conversion efficiency of38.6%. Under concentration, the maximum output power density per sun increases from 0.49 mW/cm{sup 2} to 0.51 mW/cm{sup 2} at 40 suns and then falls 0.42 mW/cm{sup 2} at 150 suns. Under external heating, a maximum of 0.59 mW/cm{sup 2} is reached at 250 °C. Even at 400 °C, the device is fully operational and exceeds room temperature performance. A defect analysis suggests that significantly higher fill factors and extension into longer wavelength ranges are possible with further development. The results prove GaInN/GaN QW solar junctions a viable and rugged topping cell for concentrator photovoltaics with minimal cooling requirements. By capturing the short range spectrum, they reduce the thermal load to any conventional cells stacked behind.

  19. Single Spatial-Mode Room-Temperature-Operated 3.0 to 3.4 micrometer Diode Lasers

    NASA Technical Reports Server (NTRS)

    Frez, Clifford F.; Soibel, Alexander; Belenky, Gregory; Shterengas, Leon; Kipshidze, Gela

    2010-01-01

    Compact, highly efficient, 3.0 to 3.4 m light emitters are in demand for spectroscopic analysis and identification of chemical substances (including methane and formaldehyde), infrared countermeasures technologies, and development of advanced infrared scene projectors. The need for these light emitters can be currently addressed either by bulky solid-state light emitters with limited power conversion efficiency, or cooled Interband Cascade (IC) semiconductor lasers. Researchers here have developed a breakthrough approach to fabrication of diode mid-IR lasers that have several advantages over IC lasers used for the Mars 2009 mission. This breakthrough is due to a novel design utilizing the strain-engineered quantum-well (QW) active region and quinternary barriers, and due to optimization of device material composition and growth conditions (growth temperatures and rates). However, in their present form, these GaSb-based laser diodes cannot be directly used as a part of sensor systems. The device spectrum is too broad to perform spectroscopic analysis of gas species, and operating currents and voltages are too high. In the current work, the emitters were fabricated as narrow-ridge waveguide index-guided lasers rather than broad stripe-gain guided multimode Fabry-Perot (FP) lasers as was done previously. These narrow-ridge waveguide mid-IR lasers exhibit much lower power consumptions, and can operate in a single spatial mode that is necessary for demonstration of single-mode distributed feedback (DBF) devices for spectroscopic applications. These lasers will enable a new generation of compact, tunable diode laser spectrometers with lower power consumption, reduced complexity, and significantly reduced development costs. These lasers can be used for the detection of HCN, C2H2, methane, and ethane.

  20. Optimization of a Radiative Transfer Forward Operator for Simulating SMOS Brightness Temperatures over the Upper Mississippi Basin, USA

    NASA Technical Reports Server (NTRS)

    Lievens, H.; Verhoest, N. E. C.; Martens, B.; VanDenBerg, M. J.; Bitar, A. Al; Tomer, S. Kumar; Merlin, O.; Cabot, F.; Kerr, Y.; DeLannoy, G. J. M.; Drusch, M.; Hendricks-Franssen, H.-J.; Vereecken, H.; Pan, M.; Wood, E. F.; Dumedah, G.; Walker, J. P.; Pauwels, V. R. N.

    2014-01-01

    The Soil Moisture and Ocean Salinity (SMOS) satellite mission is routinely providing global multi-angular observations of brightness temperature (TB) at both horizontal and vertical polarization with a 3-day repeat period. The assimilation of such data into a land surface model (LSM) may improve the skill of operational flood forecasts through an improved estimation of soil moisture (SM). To accommodate for the direct assimilation of the SMOS TB data, the LSM needs to be coupled with a radiative transfer model (RTM), serving as a forward operator for the simulation of multi-angular and multi-polarization top of atmosphere TBs. This study investigates the use of the Variable Infiltration Capacity (VIC) LSM coupled with the Community Microwave Emission Modelling platform (CMEM) for simulating SMOS TB observations over the Upper Mississippi basin, USA. For a period of 2 years (2010-2011), a comparison between SMOS TBs and simulations with literature-based RTM parameters reveals a basin averaged bias of 30K. Therefore, time series of SMOS TB observations are used to investigate ways for mitigating these large biases. Specifically, the study demonstrates the impact of the LSM soil moisture climatology in the magnitude of TB biases. After CDF matching the SM climatology of the LSM to SMOS retrievals, the average bias decreases from 30K to less than 5K. Further improvements can be made through calibration of RTM parameters related to the modeling of surface roughness and vegetation. Consequently, it can be concluded that SM rescaling and RTM optimization are efficient means for mitigating biases and form a necessary preparatory step for data assimilation.

  1. Fail-Safe Operation of a High-Temperature Magnetic Bearing Investigated for Gas Turbine Engine Applications

    NASA Technical Reports Server (NTRS)

    Choi, Benjamin B.; Montague, Gerald T.

    2002-01-01

    The Structural Mechanics and Dynamics Branch at the NASA Glenn Research Center has developed a three-axis high-temperature magnetic bearing suspension rig to enhance the safety of the bearing system up to 1000 F. This test rig can accommodate thrust and radial bearings up to a 22.84 cm (9 in.) diameter with a maximum axial loading of 22.25 kN (5000 lb) and a maximum radial loading up to 4.45 kN (1000 lb). The test facility was set up to test magnetic bearings under high-temperature (1100 F) and high-speed (20,000 rpm) conditions. The magnetic bearing is located at the center of gravity of the rotor between two high-temperature grease-packed mechanical ball bearings. The drive-end duplex angular contact ball bearing, which is in full contact, acts as a moment release and provides axial stability. The outboard end ball bearing has a 0.015-in. radial clearance between the rotor to act as a backup bearing and to compensate for axial thermal expansion. There is a 0.020-in. radial air gap between the stator pole and the rotor. The stator was wrapped with three 1-kW band heaters to create a localized hot section; the mechanical ball bearings were outside this section. Eight threaded rods supported the stator. These incorporated a plunger and Bellville washers to compensate for radial thermal expansion and provide rotor-to-stator alignment. The stator was instrumented with thermocouples and a current sensor for each coil. Eight air-cooled position sensors were mounted outside the hot section to monitor the rotor. Another sensor monitored this rotation of the outboard backup bearing. Ground fault circuit interrupts were incorporated into all power amplifier loops for personnel safety. All instrumentation was monitored and recorded on a LabView-based data acquisition system. Currently, this 12-pole heteropolar magnetic bearing has 13 thermal cycles and over 26 hr of operation at 1000 F.

  2. Effect of refrigerant flow control on the performance variation of a variable-speed heat pump operating at low outdoor temperature

    SciTech Connect

    Kim, B.H.; O'Neal, D.L.

    1999-07-01

    An experimental study was conducted to investigate the effect of electronic flow control on the performance of a variable speed heat pump typically operating in both cooling and heating mode. For this purpose, cooling and heating capacity, EER and refrigerant mass flow rate were measured as functions of compressor speed, length of capillary tube (or valve opening of the electronic valve), refrigerant charge, and outdoor temperature. From the experimental results, it was found that performance enhancement due to the electronic flow control became more significant as the operating conditions (evaporating temperature and compressor speed) deviated from the standard condition at which capacity and EER were rated for the given capillary tube.

  3. 30 CFR 1206.259 - Determination of washing allowances.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... allowance by reporting it as a separate line entry on the Form MMS-4430. (2) In conducting reviews and... washing allowance by reporting it as a separate line entry on the Form MMS-4430. When necessary or...) which are an integral part of the wash plant. (i) Allowable operating expenses include:...

  4. Operation of a New Half-Bridge Gate Driver for Enhancement - Mode GaN FETs, Type LM5113, Over a Wide Temperature Range

    NASA Technical Reports Server (NTRS)

    Patterson, Richard; Hammoud, Ahmad

    2011-01-01

    A new commercial-off-the-shelf (COTS) gate driver designed to drive both the high-side and the low-side enhancement-mode GaN FETs, National Semiconductor's type LM5113, was evaluated for operation at temperatures beyond its recommended specified limits of -40 C to +125 C. The effects of limited thermal cycling under the extended test temperature, which ranged from -194 C to +150 C, on the operation of this chip as well as restart capability at the extreme cryogenic and hot temperatures were also investigated. The driver circuit was able to maintain good operation throughout the entire test regime between -194 C and +150 C without undergoing any major changes in its outputs signals and characteristics. The limited thermal cycling performed on the device also had no effect on its performance, and the driver chip was able to successfully restart at each of the extreme temperatures of -194 C and +150 C. The plastic packaging of this device was also not affected by either the short extreme temperature exposure or the limited thermal cycling. These preliminary results indicate that this new commercial-off-the-shelf (COTS) halfbridge eGaN FET driver integrated circuit has the potential for use in space exploration missions under extreme temperature environments. Further testing is planned under long-term cycling to assess the reliability of these parts and to determine their suitability for extended use in the harsh environments of space.

  5. Effects of 2-m air temperature assimilation and a new near-surface observation operator on the NCEP Gridpoint statistical-interpolation system

    NASA Astrophysics Data System (ADS)

    Lee, Seung-Jae; Parrish, David F.; Park, Sei-Young; Wu, Wan-Shu; Greybush, Steven J.; Lee, Woo-Jin; Lord, Steven J.

    2011-08-01

    In this study, we assimilate 2-m air temperature data with the National Centers for Environmental Prediction (NCEP) regional Gridpoint Statistical Interpolation (GSI) using the WRF-NMM model forecast as a first guess. Single time analysis experiments are conducted to test the impact of 2-m air temperature data on the analysis system and the results are compared with the control run without using 2-m air temperature data. The effort is focused on understanding the characteristics of observation innovations of the 2-m air temperature data. Modifications to background errors and a simple test of nonlinear quality control are also considered. The incorporation of a comprehensive near-surface observation operator based on Monin-Obukhov similarity theory is described and tested for possible operational use with the NCEP regional GSI system. The results from this new forward operator are compared with those from the existing simple forward operator. According to the results, mesonet 2-m temperature data were found to have a considerable amount of outliers compared with other 2-m temperature data. The nighttime western and central US domains indicated a model warm bias. Stations with large innovations are distributed uniformly in the nighttime western and central domains, while they are mainly located in the large cities in the daytime eastern domain. The statistical analysis of observation innovations showed that introduction of the new forward model can reduce root-mean-square errors in observation increment statistics. The results of a short assimilation experiment indicate that the new forward operator can be employed as a short-term strategy for near-surface data assimilation in the NCEP.

  6. Room-temperature operation of npn- AlGaInAs/InP multiple quantum well transistor laser emitting at 1.3-µm wavelength.

    PubMed

    Shirao, Mizuki; Sato, Takashi; Sato, Noriaki; Nishiyama, Nobuhiko; Arai, Shigehisa

    2012-02-13

    Room-temperature pulsed operation of a 1.3-µm wavelength transistor laser (TL), consisting of a buried heterostructure (BH) with an npn configuration and an AlGaInAs/InP multiple-quantum-well (MQW) active region, was successfully attained. A threshold base current of 18 mA (threshold emitter current of 150 mA) was obtained with a stripe width of 1.3 µm and a cavity length of 500 µm. The transistor activity as well as the lasing operation were achieved at the same time, which is essential for the high-speed operation of TLs.

  7. Vietnam recommended dietary allowances 2007.

    PubMed

    Khan, Nguyen Cong; Hoan, Pham Van

    2008-01-01

    It has been well acknowledged that Vietnam is undergoing a nutrition transition. With a rapid change in the country's reform and economic growth, food supply at the macronutrient level has improved. Changes of the Vietnamese diet include significantly more foods of animal origin, and an increase of fat/oils, and ripe fruits. Consequently, nutritional problems in Vietnam now include not only malnutrition but also overweight/obesity, metabolic syndrome and other chronic diseases related to nutrition and lifestyles. The recognition of these shifts, which is also associated with morbidity and mortality, was a major factor in the need to review and update the Recommended Dietary Allowances (RDA) for the Vietnamese population. This revised RDA established an important science-based tool for evaluation of nutrition adequacy, for teaching, and for scientific communications within Vietnam. It is expected that the 2007 Vietnam RDA and its conversion to food-based dietary guidelines will facilitate education to the public, as well as the policy implementation of programs for prevention of non-communicable chronic diseases and addressing the double burden of both under and over nutrition.

  8. Continuous-wave operation of InAsSb/InP quantum - dot lasers near 2 (mu)m at room temperature

    NASA Technical Reports Server (NTRS)

    Qiu, Yueming; Uhl, David; Keo, Sam

    2004-01-01

    InAsSb quantum-dot lasers near 2 pm were demonstrated in cw operation at room temperature with a threshold current density of below 1 kA/cm, output power of 3 mW/facet and a differential quantum efficiency of 13%.

  9. Transient simulation of coolant peak temperature due to prolonged fan and/or water pump operation after the vehicle is keyed-off

    NASA Astrophysics Data System (ADS)

    Pang, Suh Chyn; Masjuki, Haji Hassan; Kalam, Md. Abul; Hazrat, Md. Ali

    2014-01-01

    Automotive designers should design a robust engine cooling system which works well in both normal and severe driving conditions. When vehicles are keyed-off suddenly after some distance of hill-climbing driving, the coolant temperature tends to increase drastically. This is because heat soak in the engine could not be transferred away in a timely manner, as both the water pump and cooling fan stop working after the vehicle is keyed-off. In this research, we aimed to visualize the coolant temperature trend over time before and after the vehicles were keyed-off. In order to prevent coolant temperature from exceeding its boiling point and jeopardizing engine life, a numerical model was further tested with prolonged fan and/or water pump operation after keying-off. One dimensional thermal-fluid simulation was exploited to model the vehicle's cooling system. The behaviour of engine heat, air flow, and coolant flow over time were varied to observe the corresponding transient coolant temperatures. The robustness of this model was proven by validation with industry field test data. The numerical results provided sensible insights into the proposed solution. In short, prolonging fan operation for 500 s and prolonging both fan and water pump operation for 300 s could reduce coolant peak temperature efficiently. The physical implementation plan and benefits yielded from implementation of the electrical fan and electrical water pump are discussed.

  10. A magnetosensitive thin-film silicon Hall-type field-effect transistor with operating temperature range expanded up to 350°C

    NASA Astrophysics Data System (ADS)

    Leonov, A. V.; Malykh, A. A.; Mordkovich, V. N.; Pavlyuk, M. I.

    2016-01-01

    We describe a magnetosensitive device consisting of a combination of a thin-film Si transistor with built-in conducting channel (fabricated by the silicon-on-insulator technology) and a Hall-type sensor (HS). The transistor has a double-gate field control system of the metal-insulator-semiconductor-insulator-metal type and operates in the regime of carrier accumulation in the channel at partial depletion of adjacent regions of the Si film. It is established that the device can operate at temperatures up to about 350°C, which is 160-180°C higher than the maximum operating temperature of HSs based on bulk Si crystals and comparable with HSs based on wide-bandgap semiconductors.

  11. Relaxor ferroelectric-based electrocaloric polymer nanocomposites with a broad operating temperature range and high cooling energy.

    PubMed

    Li, Qi; Zhang, Guangzu; Zhang, Xiaoshan; Jiang, Shenglin; Zeng, Yike; Wang, Qing

    2015-04-01

    Electrocaloric nanocomposites simultaneously derive high electrocaloric strength from inorganic inclusions and high dielectric strength from the polymer matrix to display a pronounced electrocaloric effect (ECE). By designing the inorganic filler and polymer matrix, which are both relaxor ferroelectrics with the ambient-temperature phase transition and minimized hysteresis, a large ECE becomes accessible with high cooling efficiency over a broad temperature range at and near room temperature.

  12. Experimental Investigation of an Air-Cooled Turbine Operating in a Turbojet Engine at Turbine Inlet Temperatures up to 2500 F

    NASA Technical Reports Server (NTRS)

    Cochran, Reeves P.; Dengler, Robert P.

    1961-01-01

    An experimental investigation was made of an air-cooled turbine at average turbine inlet temperatures up to 2500 F. A modified production-model 12-stage axial-flow-compressor turbojet engine operating in a static sea-level stand was used as the test vehicle. The modifications to the engine consisted of the substitution of special combustor and turbine assemblies and double-walled exhaust ducting for the standard parts of the engine. All of these special parts were air-cooled to withstand the high operating temperatures of the investigation. The air-cooled turbine stator and rotor blades were of the corrugated-insert type. Leading-edge tip caps were installed on the rotor blades to improve leading-edge cooling by diverting the discharge of coolant to regions of lower gas pressure toward the trailing edge of the blade tip. Caps varying in length from 0.15- to 0.55-chord length were used in an attempt to determine the optimum cap length for this blade. The engine was operated over a range of average turbine inlet temperatures from about 1600 to about 2500 F, and a range of average coolant-flow ratios of 0.012 to 0.065. Temperatures of the air-cooled turbine rotor blades were measured at all test conditions by the use of thermocouples and temperature-indicating paints. The results of the investigation indicated that this type of blade is feasible for operation in turbojet engines at the average turbine inlet temperatures and stress levels tested(maximums of 2500 F and 24,000 psi, respectively). An average one-third-span blade temperature of 1300 F could be maintained on 0.35-chord tip cap blades with an average coolant-flow ratio of about 0.022 when the average turbine inlet temperature was 2500 F and cooling-air temperature was about 260 F. All of the leading-edge tip cap lengths improved the cooling of the leading-edge region of the blades, particularly at low average coolant-flow ratios. At high gas temperatures, such parts as the turbine stator and the combustor

  13. Insights on the High-Temperature Operational Limits of ZrO2-Y2O3 TBCs Manufactured via Air Plasma Spray

    NASA Astrophysics Data System (ADS)

    Lima, Rogerio S.; Marple, Basil R.

    2017-02-01

    The effective high-temperature operation limit of a ZrO2-7-8 wt.%Y2O3 (YSZ) thermal barrier coating (TBC) manufactured via air plasma spray (APS) is considered to be 1300 °C. This is related to the metastable tetragonal t'-phase formed during the rapid quenching of the YSZ particles during spraying. The t'-phase transforms into the equilibrium tetragonal and cubic phases at temperatures ≥ 1300 °C, which can lead to the formation of the monoclinic phase of YSZ upon cooling to room temperature. This formation of the monoclinic phase is accompanied by a volume expansion that leads to TBC failure due to extensive micro-cracking. To further investigate this limitation, an APS YSZ TBC was sprayed on a CMSX-4 substrate. By using a thermal (laser) gradient cyclic testing, a temperature gradient was generated across the TBC/substrate system. The YSZ T-front and substrate backside T-back temperature levels were 1500 and 1000 °C, respectively. In cycle conditions (5-min or 1-h hot and 2-min cool), no TBC failure has been observed. This behavior was partially attributed to the unexpected absence of the monoclinic phase of the YSZ in the cycled coatings. Although preliminary, these results are promising regarding increasing the effective high-temperature operational limits of APS YSZ TBCs.

  14. Insights on the High-Temperature Operational Limits of ZrO2-Y2O3 TBCs Manufactured via Air Plasma Spray

    NASA Astrophysics Data System (ADS)

    Lima, Rogerio S.; Marple, Basil R.

    2017-03-01

    The effective high-temperature operation limit of a ZrO2-7-8 wt.%Y2O3 (YSZ) thermal barrier coating (TBC) manufactured via air plasma spray (APS) is considered to be 1300 °C. This is related to the metastable tetragonal t'-phase formed during the rapid quenching of the YSZ particles during spraying. The t'-phase transforms into the equilibrium tetragonal and cubic phases at temperatures ≥ 1300 °C, which can lead to the formation of the monoclinic phase of YSZ upon cooling to room temperature. This formation of the monoclinic phase is accompanied by a volume expansion that leads to TBC failure due to extensive micro-cracking. To further investigate this limitation, an APS YSZ TBC was sprayed on a CMSX-4 substrate. By using a thermal (laser) gradient cyclic testing, a temperature gradient was generated across the TBC/substrate system. The YSZ T- front and substrate backside T- back temperature levels were 1500 and 1000 °C, respectively. In cycle conditions (5-min or 1-h hot and 2-min cool), no TBC failure has been observed. This behavior was partially attributed to the unexpected absence of the monoclinic phase of the YSZ in the cycled coatings. Although preliminary, these results are promising regarding increasing the effective high-temperature operational limits of APS YSZ TBCs.

  15. Growth and Study of Novel 3-4 m Antimonide III-V Diode Lasers Operating at Room Temperature (Hole Well Laser)

    DTIC Science & Technology

    2006-04-01

    BEP ) for Ga deduced from RHEED oscillations. A typical RHEED oscillations record for Gallium is represented in Figure 3.1. Each osc These...oscillations are observed at ifferent temperatures of cells (which corresponds to different Ga BEP ) allowing the realizat...6,0x10-7 7,0x10-7 8,0x10-7 0,4 0,6 0,8 1,0 V =1,23173*106*P -0,00167Ga Ga V G a(m l/s ec ) BEP (Torr) valve. Then, the valve opening allows to change

  16. Development and evaluation of magnetic and electrical materials capable of operating in the 800 to 1600 F temperature range

    NASA Technical Reports Server (NTRS)

    Kueser, P. E.; Toth, J. W.

    1973-01-01

    The results are summarized of a research program on electrical materials for advanced space electric power systems. The areas investigated included improved high-temperature magnetic materials, high-temperature capacitor materials, ceramic-to-metal bore-seal technology, and simulated-space environmental testing of electric-power system components

  17. Parameters for Quantitative Comparison of Two-, Three-, and Four-level Laser Media, Operating Wavelengths, and Temperatures

    DTIC Science & Technology

    2010-08-01

    for Er3+, Nd3+, Yb3+, and Ho3+ in YAG, as a function of temperature. 15. SUBJECT TERMS Erbium lasers, holmium lasers, laser physics, neodymium...Nd, Yb, and Ho in YAG, as a function of temperature. Index Terms—Erbium lasers, holmium lasers, laser physics, neodymium lasers, quasi-four

  18. Fiber-optic flow sensors for high-temperature environment operation up to 800°C.

    PubMed

    Chen, Rongzhang; Yan, Aidong; Wang, Qingqing; Chen, Kevin P

    2014-07-01

    This Letter presents an all-optical high-temperature flow sensor based on hot-wire anemometry. High-attenuation fibers (HAFs) were used as the heating elements. High-temperature-stable regenerated fiber Bragg gratings were inscribed in HAFs and in standard telecom fibers as temperature sensors. Using in-fiber light as both the heating power source and the interrogation light source, regenerative fiber Bragg grating sensors were used to gauge the heat transfer from an optically powered heating element induced by the gas flow. Reliable gas flow measurements were demonstrated between 0.066  m/s and 0.66  m/s from the room temperature to 800°C. This Letter presents a compact, low-cost, and multiflexible approach to measure gas flow for high-temperature harsh environments.

  19. Silicon solar cell development and radiation effects study for low temperature and low illumination intensity operation, volume 2

    NASA Technical Reports Server (NTRS)

    Kirkpatrick, A. R.

    1972-01-01

    The results are presented of a study to determine the effect of in-situ proton irradiation upon low temperature, low intensity performance of several cell types. The cell types were selected in an attempt to distinguish variations in temperature-dependent radiation resistance which could be attributed to the n-p or p-n structure, diffused or implanted junctions, crucible grown or float-zone type base material, and high or low base resistivity. The results indicate that while expected variations of performance occur at room temperature, all cell types degrade more or less similarly at lower temperatures with normalized degradation becoming increasingly rapid as temperature is reduced. Recommendations for an optimized cell for Jupiter probe use are included along with a definition of the testing required on these cells to insure good performance characteristics.

  20. Room-temperature continuous operation of InAsSb quantum-dot lasers near 2 mu m based on (100) InP substrate

    NASA Technical Reports Server (NTRS)

    Qui, Y.; Uhl, D.; Keo, S.

    2003-01-01

    Single-stack InAsSb self-assembled quantum-dot lasers based on (001) InP substrate have been grown by metalorganic vapor-phase epitaxy. The narrow ridge waveguide lasers lased at wavelengths near 2 mu m up to 25 degrees C in continuous-wave operation. At room temperature, a differential quantum efficiency of 13 percent is obtained and the maximum output optical power reaches 3 mW per facet with a threshold current density of 730 A/cm(sup 2). With increasing temperature the emission wavelength is extremely temperature stable, and a very low wavelength temperature sensitivity of 0.05 nm/degrees C is measured, which is even lower than that caused by the refractive index change.

  1. Calibration of catalyst temperature in automotive engines over coldstart operation in the presence of different random noises and uncertainty: Implementation of generalized Gaussian process regression machine

    NASA Astrophysics Data System (ADS)

    Azad, Nasser L.; Mozaffari, Ahmad

    2015-12-01

    The main scope of the current study is to develop a systematic stochastic model to capture the undesired uncertainty and random noises on the key parameters affecting the catalyst temperature over the coldstart operation of automotive engine systems. In the recent years, a number of articles have been published which aim at the modeling and analysis of automotive engines' behavior during coldstart operations by using regression modeling methods. Regarding highly nonlinear and uncertain nature of the coldstart operation, calibration of the engine system's variables, for instance the catalyst temperature, is deemed to be an intricate task, and it is unlikely to develop an exact physics-based nonlinear model. This encourages automotive engineers to take advantage of knowledge-based modeling tools and regression approaches. However, there exist rare reports which propose an efficient tool for coping with the uncertainty associated with the collected database. Here, the authors introduce a random noise to experimentally derived data and simulate an uncertain database as a representative of the engine system's behavior over coldstart operations. Then, by using a Gaussian process regression machine (GPRM), a reliable model is used for the sake of analysis of the engine's behavior. The simulation results attest the efficacy of GPRM for the considered case study. The research outcomes confirm that it is possible to develop a practical calibration tool which can be reliably used for modeling the catalyst temperature.

  2. High-speed highly temperature stable 980 nm VCSELs operating at 25 Gb/s at up to 85 °C for short reach optical interconnects

    NASA Astrophysics Data System (ADS)

    Mutig, Alex; Lott, James A.; Blokhin, Sergey A.; Moser, Philip; Wolf, Philip; Hofmann, Werner; Nadtochiy, Alexey M.; Bimberg, Dieter

    2011-03-01

    The progressive penetration of optical communication links into traditional copper interconnect markets greatly expands the applications of vertical cavity surface emitting lasers (VCSELs) for the next-generation of board-to-board, moduleto- module, chip-to-chip, and on-chip optical interconnects. Stability of the VCSEL parameters at high temperatures is indispensable for such applications, since these lasers typically reside directly on or near integrated circuit chips. Here we present 980 nm oxide-confined VCSELs operating error-free at bit rates up to 25 Gbit/s at temperatures as high as 85 °C without adjustment of the drive current and peak-to-peak modulation voltage. The driver design is therefore simplified and the power consumption of the driver electronics is lowered, reducing the production and operational costs. Small and large signal modulation experiments at various temperatures from 20 up to 85 °C for lasers with different oxide aperture diameters are presented in order to analyze the physical processes controlling the performance of the VCSELs. Temperature insensitive maximum -3 dB bandwidths of around 13-15 GHz for VCSELs with aperture diameters of 10 μm and corresponding parasitic cut-off frequencies exceeding 22 GHz are observed. Presented results demonstrate the suitability of our VCSELs for practical high speed and high temperature stable short-reach optical links.

  3. 30 CFR 1206.57 - Determination of transportation allowances.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... equipment) which are an integral part of the transportation system. (i) Allowable operating expenses include... either a straight-line depreciation method based on the life of equipment or on the life of the...

  4. 40 CFR 264.113 - Closure; time allowed for closure.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... Administrator may allow an owner or operator to receive only non-hazardous wastes in a landfill, land treatment... corrective action program, compile all ground-water monitoring data, and evaluate the effect of the...

  5. 40 CFR 265.113 - Closure; time allowed for closure.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... Regional Administrator may allow an owner or operator to receive non-hazardous wastes in a landfill, land... corrective action program, compile all ground-water monitoring data, and evaluate the effect of the...

  6. 40 CFR 265.113 - Closure; time allowed for closure.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... Regional Administrator may allow an owner or operator to receive non-hazardous wastes in a landfill, land... corrective action program, compile all ground-water monitoring data, and evaluate the effect of the...

  7. 40 CFR 265.113 - Closure; time allowed for closure.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... Regional Administrator may allow an owner or operator to receive non-hazardous wastes in a landfill, land... corrective action program, compile all ground-water monitoring data, and evaluate the effect of the...

  8. 40 CFR 264.113 - Closure; time allowed for closure.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... Administrator may allow an owner or operator to receive only non-hazardous wastes in a landfill, land treatment... corrective action program, compile all ground-water monitoring data, and evaluate the effect of the...

  9. 40 CFR 264.113 - Closure; time allowed for closure.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... Administrator may allow an owner or operator to receive only non-hazardous wastes in a landfill, land treatment... corrective action program, compile all ground-water monitoring data, and evaluate the effect of the...

  10. 40 CFR 264.113 - Closure; time allowed for closure.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... Administrator may allow an owner or operator to receive only non-hazardous wastes in a landfill, land treatment... corrective action program, compile all ground-water monitoring data, and evaluate the effect of the...

  11. Inactivation of a 25.5 µm Enterococcus faecalis biofilm by a room-temperature, battery-operated, handheld air plasma jet

    NASA Astrophysics Data System (ADS)

    Pei, X.; Lu, X.; Liu, J.; Liu, D.; Yang, Y.; Ostrikov, K.; Chu, Paul K.; Pan, Y.

    2012-04-01

    Effective biofilm inactivation using a handheld, mobile plasma jet powered by a 12 V dc battery and operated in open air without any external gas supply is reported. This cold, room-temperature plasma is produced in self-repetitive nanosecond discharges with current pulses of ˜100 ns duration, current peak amplitude of ˜6 mA and repetition rate of ˜20 kHz. It is shown that the reactive plasma species penetrate to the bottom layer of a 25.5 µm-thick Enterococcus faecalis biofilm and produce a strong bactericidal effect. This is the thickest reported biofilm inactivated using room-temperature air plasmas.

  12. Optimization of solar cells for air mass zero operation and a study of solar cells at high temperatures, phase 2

    NASA Technical Reports Server (NTRS)

    Hovel, H.; Woodall, J. M.

    1976-01-01

    Crystal growth procedures, fabrication techniques, and theoretical analysis were developed in order to make GaAlAs-GaAs solar cell structures which exhibit high performance at air mass 0 illumination and high temperature conditions.

  13. 40 CFR Table 2 to Subpart Sssss of... - Operating Limits

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... operating temperature at the inlet of the catalyst bed of the oxidizer at or above the minimum allowable... activity level of the catalyst at least every 12 months. 7. Each affected batch process unit For each batch..., maintain the hourly average operating temperature at the inlet of the catalyst bed at or above the...

  14. 40 CFR Table 2 to Subpart Sssss of... - Operating Limits

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... operating temperature at the inlet of the catalyst bed of the oxidizer at or above the minimum allowable... activity level of the catalyst at least every 12 months. 7. Each affected batch process unit For each batch..., maintain the hourly average operating temperature at the inlet of the catalyst bed at or above the...

  15. 40 CFR Table 2 to Subpart Sssss of... - Operating Limits

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... operating temperature at the inlet of the catalyst bed of the oxidizer at or above the minimum allowable... activity level of the catalyst at least every 12 months. 7. Each affected batch process unit For each batch..., maintain the hourly average operating temperature at the inlet of the catalyst bed at or above the...

  16. Thermal dynamic in hyporheic zone response to river temperatures formed by reservoir operations in Xinanjiang River, China

    NASA Astrophysics Data System (ADS)

    Chen, X.; Zhao, J.; Chen, L.; Tao, X.; Zhao, Z.

    2012-12-01

    Understanding heat fluxes through hyporheic zones (HZ) becomes increasingly important as anthropogenic influences and changing climate alter river thermal regimes. The HZ directly interacts with river thermal regimes by storing and releasing heat over a range of timescales. Alteration of HZ can lead to shifts in aquatic species composition and changes in biogeochemical processes. In this study we examine a reach of the Xinanjiang, China downstream of the Xinanjiang Dam. The Xinanjiang Dam introduces a low temperature water (LTW) region to the downstream of a length of 23 km and an area of 9.9 km2, which greatly changes the downstream thermal regime. However, how and to what extent the LTW in stream affect the HZ temperature distribution and, ulteriorly, the full range of the river ecosystem are still not completely understood. We quantify hyporheic exchange and heat transport induced by LTW by field experiments and numerical simulations for coupled groundwater flow and heat transport. Both surface and subsurface water temperature are measured in a study region for model validation. The hydraulic head and water temperature along the water-aquifer interface are considered as the input boundaries for groundwater models. The upwelling water with short streamline paths shows the same temperature pattern as surface water but the temperature of water that comes out from the deep subsurface zones rises much higher and shows a relatively lower variation. However, with the continuing exchange of surface LTW and groundwater, the low temperature spreads over the entire domain. Detailed field characterization and groundwater modeling indicate residence times of hyporheic flux can vary from hours to months. A significant implication is that the LTW released from upstream reservoir contributes to the downstream temperature field and potential degradation of habitats in hyporheic zones.

  17. Investigating the origin of efficiency droop by profiling the temperature across the multi-quantum well of an operating light-emitting diode

    SciTech Connect

    Jung, Euihan; Hwang, Gwangseok; Chung, Jaehun; Kwon, Ohmyoung; Han, Jaecheon; Moon, Yong-Tae; Seong, Tae-Yeon

    2015-01-26

    Performance degradation resulting from efficiency droop during high-power operation is a critical problem in the development of high-efficiency light-emitting diodes (LEDs). In order to resolve the efficiency droop and increase the external quantum efficiency of LEDs, the droop's origin should be identified first. To experimentally investigate the cause of efficiency droop, we used null-point scanning thermal microscopy to quantitatively profile the temperature distribution on the cross section of the epi-layers of an operating GaN-based vertical LED with nanoscale spatial resolution at four different current densities. The movement of temperature peak towards the p-GaN side as the current density increases suggests that more heat is generated by leakage current than by Auger recombination. We therefore suspect that at higher current densities, current leakage becomes the dominant cause of the droop problem.

  18. Ionometric determination of fluorides at low temperatures

    SciTech Connect

    Kostyukova, I.S.; Ennan, A.A.; Dzerzhko, E.K.; Leivikova, A.A.

    1995-12-01

    A method for determining fluoride ions in solution at low temperatures using a solid-contact fluorine-selective electrode (FSE) has been developed. The effect of temperature (60 to -15{degrees}C) on the calibration slope, potential equilibrium time, and operational stability is studied; the effect of an organic additive (cryoprotector) on the calibration slope is also studied. The temperature relationships obtained for the solid-contact FSEs allow appropriate corrections to be applied to the operational algorithm of the {open_quotes}Ftoring{close_quotes} hand-held semiautomatic HF gas analyzer for the operational temperature range of -16 to 60{degrees}C.

  19. 30 CFR 1206.458 - Determination of washing allowances.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... installation of capital equipment) which are an integral part of the wash plant. (i) Allowable operating.... (A) To compute depreciation, the lessee may elect to use either a straight-line depreciation method... reporting period. (4) Washing allowances must be reported as a separate line on the Form MMS-4430,...

  20. Direct use of low temperature geothermal water by Aquafarms International, Inc. for freshwater aquaculture (prawns and associated species). An operations and maintenance manual

    SciTech Connect

    Broughton, R.; Price, M.; Price, V.; Grajcer, D.

    1984-04-01

    In connection with an ongoing commercial aquaculture project in the Coachella Valley, California; a twelve month prawn growout demonstration project was conducted. This project began in August, 1979 and involved the use of low temperature (85/sup 0/F) geothermal waters to raise freshwater prawns, Macrobrachium rosenbergii (deMan), in earthen ponds. The following publication is an operations and maintenance guide which may by useful for those interested in conducting similar enterprises.