Measure Guideline: High Efficiency Natural Gas Furnaces

DOE Office of Scientific and Technical Information (OSTI.GOV)

Brand, L.; Rose, W.

2012-10-01

This Measure Guideline covers installation of high-efficiency gas furnaces. Topics covered include when to install a high-efficiency gas furnace as a retrofit measure, how to identify and address risks, and the steps to be used in the selection and installation process. The guideline is written for Building America practitioners and HVAC contractors and installers. It includes a compilation of information provided by manufacturers, researchers, and the Department of Energy as well as recent research results from the Partnership for Advanced Residential Retrofit (PARR) Building America team.

A low-power, high-efficiency Ka-band TWTA

NASA Astrophysics Data System (ADS)

Curren, Arthur N.; Dayton, James A., Jr.; Palmer, Raymond W.; Force, Dale A.; Tamashiro, Rodney N.; Wilson, John F.; Dombro, Louis; Harvey, Wayne L.

1992-03-01

NASA has developed a new class of Ka-band TWT amplifiers (TWTAs) which achieve their high efficiency/low power performance goals by means of an advanced dynamic velocity taper (DVT). The DVT is characterized by a continuous, nonlinear reduction in helix pitch from its initial synchronous value in the output section of the TWT to near the end of the helix. Another efficiency-maximizing feature is the inclusion of a multistage depressed collector employing oxygen-free, high-conductivity Cu electrodes treated for secondary electron emission suppression by means of ion bombardment. An efficiency of 43 percent is expected to be reached.

High Efficiency Low Global Warming Potential Compressor

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cogswell, Frederick; Verma, Parmesh

During this project UTRC designed a novel compressor for use with new low Global-Warming-Potential (GWP) refrigerants. Through two design and testing iterations, UTRC advanced the compressor technology from TRL3 to TRL5. The target application was a 5 Tons of Refrigeration (TR) capacity Roof-Top Unit (RTU), although this technology may be applied to other low-capacity systems such as residential. The prototype unit met all design goals at the ARI-A rating condition and requires high efficiency motor to meet high performance targets at the ARI-B condition. This technology may be used in high efficiency units and with seasonal energy efficiency rating (SEER)more » exceeding 20. A preliminary cost analysis estimated that there would be less than $25/kbtuh cost impact to the customer.« less

High-efficiency in situ resonant inelastic x-ray scattering (iRIXS) endstation at the Advanced Light Source

DOE PAGES

Qiao, Ruimin; Li, Qinghao; Zhuo, Zengqing; ...

2017-03-17

In this paper, an endstation with two high-efficiency soft x-ray spectrographs was developed at Beamline 8.0.1 of the Advanced Light Source, Lawrence Berkeley National Laboratory. The endstation is capable of performing soft x-ray absorption spectroscopy, emission spectroscopy, and, in particular, resonant inelastic soft x-ray scattering (RIXS). Two slit-less variable line-spacing grating spectrographs are installed at different detection geometries. The endstation covers the photon energy range from 80 to 1500 eV. For studying transition-metal oxides, the large detection energy window allows a simultaneous collection of x-ray emission spectra with energies ranging from the O K-edge to the Ni L-edge without movingmore » any mechanical components. The record-high efficiency enables the recording of comprehensive two-dimensional RIXS maps with good statistics within a short acquisition time. By virtue of the large energy window and high throughput of the spectrographs, partial fluorescence yield and inverse partial fluorescence yield signals could be obtained for all transition metal L-edges including Mn. Finally and moreover, the different geometries of these two spectrographs (parallel and perpendicular to the horizontal polarization of the beamline) provide contrasts in RIXS features with two different momentum transfers.« less

Advances in a high efficiency commercial pulse tube cooler

NASA Astrophysics Data System (ADS)

Zhang, Yibing; Li, Haibing; Wang, Xiaotao; Dai, Wei; Yang, Zhaohui; Luo, Ercang

2017-12-01

The pulse tube cryocooler has the advantage of no moving part at the cold end and offers a high reliability. To further extend its use in commercial applications, efforts are still needed to improve efficiency, reliability and cost effectiveness. This paper generalizes several key innovations in our newest cooler. The cooler consists of a moving magnet compressor with dual-opposed pistons, and a co-axial cold finger. Ambient displacers are employed to recover the expansion work to increase cooling efficiency. Inside the cold finger, the conventional flow straightener screens are replaced by a tapered throat between the cold heat exchanger and the pulse tube to strengthen its immunity to the working gas contamination as well as to simplify the manufacturing processes. The cold heat exchanger is made by copper forging process which further reduces the cost. Inside the compressor, a new gas bearing design has brought in assembling simplicity and running reliability. Besides the cooler itself, electronic controller is also important for actual application. A dual channel and dual driving mode control mechanism has been selected, which reduces the vibration to a minimum, meanwhile the cool-down speed becomes faster and run-time efficiency is higher. With these innovations, the cooler TC4189 reached a no-load temperature of 44 K and provided 15 W cooling power at 80K, with an input electric power of 244 W and a cooling water temperature of 23 ℃. The efficiency reached 16.9% of Carnot at 80 K. The whole system has a total mass of 4.3 kg.

High Efficiency Centrifugal Compressor for Rotorcraft Applications

NASA Technical Reports Server (NTRS)

Medic, Gorazd; Sharma, Om P.; Jongwook, Joo; Hardin, Larry W.; McCormick, Duane C.; Cousins, William T.; Lurie, Elizabeth A.; Shabbir, Aamir; Holley, Brian M.; Van Slooten, Paul R.

2017-01-01

A centrifugal compressor research effort conducted by United Technologies Research Center under NASA Research Announcement NNC08CB03C is documented. The objectives were to identify key technical barriers to advancing the aerodynamic performance of high-efficiency, high work factor, compact centrifugal compressor aft-stages for turboshaft engines; to acquire measurements needed to overcome the technical barriers and inform future designs; to design, fabricate, and test a new research compressor in which to acquire the requisite flow field data. A new High-Efficiency Centrifugal Compressor stage -- splittered impeller, splittered diffuser, 90 degree bend, and exit guide vanes -- with aerodynamically aggressive performance and configuration (compactness) goals were designed, fabricated, and subquently tested at the NASA Glenn Research Center.

High power disk lasers: advances and applications

NASA Astrophysics Data System (ADS)

Havrilla, David; Holzer, Marco

2011-02-01

Though the genesis of the disk laser concept dates to the early 90's, the disk laser continues to demonstrate the flexibility and the certain future of a breakthrough technology. On-going increases in power per disk, and improvements in beam quality and efficiency continue to validate the genius of the disk laser concept. As of today, the disk principle has not reached any fundamental limits regarding output power per disk or beam quality, and offers numerous advantages over other high power resonator concepts, especially over monolithic architectures. With well over 1000 high power disk lasers installations, the disk laser has proven to be a robust and reliable industrial tool. With advancements in running cost, investment cost and footprint, manufacturers continue to implement disk laser technology with more vigor than ever. This paper will explain important details of the TruDisk laser series and process relevant features of the system, like pump diode arrangement, resonator design and integrated beam guidance. In addition, advances in applications in the thick sheet area and very cost efficient high productivity applications like remote welding, remote cutting and cutting of thin sheets will be discussed.

Processing technology for high efficiency silicon solar cells

NASA Technical Reports Server (NTRS)

Spitzer, M. B.; Keavney, C. J.

1985-01-01

Recent advances in silicon solar cell processing have led to attainment of conversion efficiency approaching 20%. The basic cell design is investigated and features of greatest importance to achievement of 20% efficiency are indicated. Experiments to separately optimize high efficiency design features in test structures are discussed. The integration of these features in a high efficiency cell is examined. Ion implantation has been used to achieve optimal concentrations of emitter dopant and junction depth. The optimization reflects the trade-off between high sheet conductivity, necessary for high fill factor, and heavy doping effects, which must be minimized for high open circuit voltage. A second important aspect of the design experiments is the development of a passivation process to minimize front surface recombination velocity. The manner in which a thin SiO2 layer may be used for this purpose is indicated without increasing reflection losses, if the antireflection coating is properly designed. Details are presented of processing intended to reduce recombination at the contact/Si interface. Data on cell performance (including CZ and ribbon) and analysis of loss mechanisms are also presented.

Advanced interface modelling of n-Si/HNO3 doped graphene solar cells to identify pathways to high efficiency

NASA Astrophysics Data System (ADS)

Zhao, Jing; Ma, Fa-Jun; Ding, Ke; Zhang, Hao; Jie, Jiansheng; Ho-Baillie, Anita; Bremner, Stephen P.

2018-03-01

In graphene/silicon solar cells, it is crucial to understand the transport mechanism of the graphene/silicon interface to further improve power conversion efficiency. Until now, the transport mechanism has been predominantly simplified as an ideal Schottky junction. However, such an ideal Schottky contact is never realised experimentally. According to literature, doped graphene shows the properties of a semiconductor, therefore, it is physically more accurate to model graphene/silicon junction as a Heterojunction. In this work, HNO3-doped graphene/silicon solar cells were fabricated with the power conversion efficiency of 9.45%. Extensive characterization and first-principles calculations were carried out to establish an advanced technology computer-aided design (TCAD) model, where p-doped graphene forms a straddling heterojunction with the n-type silicon. In comparison with the simple Schottky junction models, our TCAD model paves the way for thorough investigation on the sensitivity of solar cell performance to graphene properties like electron affinity. According to the TCAD heterojunction model, the cell performance can be improved up to 22.5% after optimizations of the antireflection coatings and the rear structure, highlighting the great potentials for fabricating high efficiency graphene/silicon solar cells and other optoelectronic devices.

Final Scientific Report - Wireless and Sensing Solutions Advancing Industrial Efficiency

DOE Office of Scientific and Technical Information (OSTI.GOV)

Budampati, Rama; McBrady, Adam; Nusseibeh, Fouad

2009-09-28

The project team's goal for the Wireless and Sensing Solution Advancing Industrial Efficiency award (DE-FC36-04GO14002) was to develop, demonstrate, and test a number of leading edge technologies that could enable the emergence of wireless sensor and sampling systems for the industrial market space. This effort combined initiatives in advanced sensor development, configurable sampling and deployment platforms, and robust wireless communications to address critical obstacles in enabling enhanced industrial efficiency.

Advanced Passivation Technology and Loss Factor Minimization for High Efficiency Solar Cells.

PubMed

Park, Cheolmin; Balaji, Nagarajan; Jung, Sungwook; Choi, Jaewoo; Ju, Minkyu; Lee, Seunghwan; Kim, Jungmo; Bong, Sungjae; Chung, Sungyoun; Lee, Youn-Jung; Yi, Junsin

2015-10-01

High-efficiency Si solar cells have attracted great attention from researchers, scientists, photovoltaic (PV) industry engineers for the past few decades. With thin wafers, surface passivation becomes necessary to increase the solar cells efficiency by overcoming several induced effects due to associated crystal defects and impurities of c-Si. This paper discusses suitable passivation schemes and optimization techniques to achieve high efficiency at low cost. SiNx film was optimized with higher transmittance and reduced recombination for using as an effective antireflection and passivation layer to attain higher solar cell efficiencies. The higher band gap increased the transmittance with reduced defect states that persisted at 1.68 and 1.80 eV in SiNx films. The thermal stability of SiN (Si-rich)/SiN (N-rich) stacks was also studied. Si-rich SiN with a refractive index of 2.7 was used as a passivation layer and N-rich SiN with a refractive index of 2.1 was used for thermal stability. An implied Voc of 720 mV with a stable lifetime of 1.5 ms was obtained for the stack layer after firing. Si-N and Si-H bonding concentration was analyzed by FTIR for the correlation of thermally stable passivation mechanism. The passivation property of spin coated Al2O3 films was also investigated. An effective surface recombination velocity of 55 cm/s with a high density of negative fixed charges (Qf) on the order of 9 x 10(11) cm(-2) was detected in Al2O3 films.

High efficiency video coding for ultrasound video communication in m-health systems.

PubMed

Panayides, A; Antoniou, Z; Pattichis, M S; Pattichis, C S; Constantinides, A G

2012-01-01

Emerging high efficiency video compression methods and wider availability of wireless network infrastructure will significantly advance existing m-health applications. For medical video communications, the emerging video compression and network standards support low-delay and high-resolution video transmission, at the clinically acquired resolution and frame rates. Such advances are expected to further promote the adoption of m-health systems for remote diagnosis and emergency incidents in daily clinical practice. This paper compares the performance of the emerging high efficiency video coding (HEVC) standard to the current state-of-the-art H.264/AVC standard. The experimental evaluation, based on five atherosclerotic plaque ultrasound videos encoded at QCIF, CIF, and 4CIF resolutions demonstrates that 50% reductions in bitrate requirements is possible for equivalent clinical quality.

High efficiency IR supercontinuum generation and applications

NASA Astrophysics Data System (ADS)

Yin, Stuart (Shizhuo); Ruffin, Paul; Brantley, Christina; Edwards, Eugene; Yang, Chia-En; Luo, Claire

2010-08-01

In this paper, we have reviewed our recent works on IR supercontinuum generation (SCG) and its applications. First, we provide a brief review on the physical mechanism of the supercontinuum generation. Second, the advance of SCG in single crystal sapphire fibers is reviewed and introduced. In particular, we discussed how to fabricate thinned sapphire fiber and use it for high efficiency SCG. Finally, experimental results of chemical analysis with supercontinuum source are reviewed.

Highly Efficient Coherent Optical Memory Based on Electromagnetically Induced Transparency

NASA Astrophysics Data System (ADS)

Hsiao, Ya-Fen; Tsai, Pin-Ju; Chen, Hung-Shiue; Lin, Sheng-Xiang; Hung, Chih-Chiao; Lee, Chih-Hsi; Chen, Yi-Hsin; Chen, Yong-Fan; Yu, Ite A.; Chen, Ying-Cheng

2018-05-01

Quantum memory is an important component in the long-distance quantum communication based on the quantum repeater protocol. To outperform the direct transmission of photons with quantum repeaters, it is crucial to develop quantum memories with high fidelity, high efficiency and a long storage time. Here, we achieve a storage efficiency of 92.0 (1.5)% for a coherent optical memory based on the electromagnetically induced transparency scheme in optically dense cold atomic media. We also obtain a useful time-bandwidth product of 1200, considering only storage where the retrieval efficiency remains above 50%. Both are the best record to date in all kinds of schemes for the realization of optical memory. Our work significantly advances the pursuit of a high-performance optical memory and should have important applications in quantum information science.

Highly Efficient Coherent Optical Memory Based on Electromagnetically Induced Transparency.

PubMed

Hsiao, Ya-Fen; Tsai, Pin-Ju; Chen, Hung-Shiue; Lin, Sheng-Xiang; Hung, Chih-Chiao; Lee, Chih-Hsi; Chen, Yi-Hsin; Chen, Yong-Fan; Yu, Ite A; Chen, Ying-Cheng

2018-05-04

Quantum memory is an important component in the long-distance quantum communication based on the quantum repeater protocol. To outperform the direct transmission of photons with quantum repeaters, it is crucial to develop quantum memories with high fidelity, high efficiency and a long storage time. Here, we achieve a storage efficiency of 92.0 (1.5)% for a coherent optical memory based on the electromagnetically induced transparency scheme in optically dense cold atomic media. We also obtain a useful time-bandwidth product of 1200, considering only storage where the retrieval efficiency remains above 50%. Both are the best record to date in all kinds of schemes for the realization of optical memory. Our work significantly advances the pursuit of a high-performance optical memory and should have important applications in quantum information science.

The Global Experience of Deployment of Energy-Efficient Technologies in High-Rise Construction

NASA Astrophysics Data System (ADS)

Potienko, Natalia D.; Kuznetsova, Anna A.; Solyakova, Darya N.; Klyueva, Yulia E.

2018-03-01

The objective of this research is to examine issues related to the increasing importance of energy-efficient technologies in high-rise construction. The aim of the paper is to investigate modern approaches to building design that involve implementation of various energy-saving technologies in diverse climates and at different structural levels, including the levels of urban development, functionality, planning, construction and engineering. The research methodology is based on the comprehensive analysis of the advanced global expertise in the design and construction of energy-efficient high-rise buildings, with the examination of their positive and negative features. The research also defines the basic principles of energy-efficient architecture. Besides, it draws parallels between the climate characteristics of countries that lead in the field of energy-efficient high-rise construction, on the one hand, and the climate in Russia, on the other, which makes it possible to use the vast experience of many countries, wholly or partially. The paper also gives an analytical review of the results arrived at by implementing energy efficiency principles into high-rise architecture. The study findings determine the impact of energy-efficient technologies on high-rise architecture and planning solutions. In conclusion, the research states that, apart from aesthetic and compositional interpretation of architectural forms, an architect nowadays has to address the task of finding a synthesis between technological and architectural solutions, which requires knowledge of advanced technologies. The study findings reveal that the implementation of modern energy-efficient technologies into high-rise construction is of immediate interest and is sure to bring long-term benefits.

Method and system for advancement of a borehole using a high power laser

DOE Office of Scientific and Technical Information (OSTI.GOV)

Moxley, Joel F.; Land, Mark S.; Rinzler, Charles C.

2014-09-09

There is provided a system, apparatus and methods for the laser drilling of a borehole in the earth. There is further provided with in the systems a means for delivering high power laser energy down a deep borehole, while maintaining the high power to advance such boreholes deep into the earth and at highly efficient advancement rates, a laser bottom hole assembly, and fluid directing techniques and assemblies for removing the displaced material from the borehole.

Simple Retrofit High-Efficiency Natural Gas Water Heater Field Test

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schoenbauer, Ben

High-performance water heaters are typically more time consuming and costly to install in retrofit applications, making high performance water heaters difficult to justify economically. However, recent advancements in high performance water heaters have targeted the retrofit market, simplifying installations and reducing costs. Four high efficiency natural gas water heaters designed specifically for retrofit applications were installed in single-family homes along with detailed monitoring systems to characterize their savings potential, their installed efficiencies, and their ability to meet household demands. The water heaters tested for this project were designed to improve the cost-effectiveness and increase market penetration of high efficiency watermore » heaters in the residential retrofit market. The retrofit high efficiency water heaters achieved their goal of reducing costs, maintaining savings potential and installed efficiency of other high efficiency water heaters, and meeting the necessary capacity in order to improve cost-effectiveness. However, the improvements were not sufficient to achieve simple paybacks of less than ten years for the incremental cost compared to a minimum efficiency heater. Significant changes would be necessary to reduce the simple payback to six years or less. Annual energy savings in the range of $200 would also reduce paybacks to less than six years. These energy savings would require either significantly higher fuel costs (greater than $1.50 per therm) or very high usage (around 120 gallons per day). For current incremental costs, the water heater efficiency would need to be similar to that of a heat pump water heater to deliver a six year payback.« less

Surface Catalytic Efficiency of Advanced Carbon Carbon Candidate Thermal Protection Materials for SSTO Vehicles

NASA Technical Reports Server (NTRS)

Stewart, David A.

1996-01-01

The catalytic efficiency (atom recombination coefficients) for advanced ceramic thermal protection systems was calculated using arc-jet data. Coefficients for both oxygen and nitrogen atom recombination on the surfaces of these systems were obtained to temperatures of 1650 K. Optical and chemical stability of the candidate systems to the high energy hypersonic flow was also demonstrated during these tests.

Simple Retrofit High-Efficiency Natural Gas Water Heater Field Test

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schoenbauer, Ben

High performance water heaters are typically more time consuming and costly to install in retrofit applications, making high performance water heaters difficult to justify economically. However, recent advancements in high performance water heaters have targeted the retrofit market, simplifying installations and reducing costs. Four high efficiency natural gas water heaters designed specifically for retrofit applications were installed in single-family homes along with detailed monitoring systems to characterize their savings potential, their installed efficiencies, and their ability to meet household demands. The water heaters tested for this project were designed to improve the cost-effectiveness and increase market penetration of high efficiencymore » water heaters in the residential retrofit market. The retrofit high efficiency water heaters achieved their goal of reducing costs, maintaining savings potential and installed efficiency of other high efficiency water heaters, and meeting the necessary capacity in order to improve cost-effectiveness. However, the improvements were not sufficient to achieve simple paybacks of less than ten years for the incremental cost compared to a minimum efficiency heater. Significant changes would be necessary to reduce the simple payback to six years or less. Annual energy savings in the range of $200 would also reduce paybacks to less than six years. These energy savings would require either significantly higher fuel costs (greater than $1.50 per therm) or very high usage (around 120 gallons per day). For current incremental costs, the water heater efficiency would need to be similar to that of a heat pump water heater to deliver a six year payback.« less

Highly efficient solar-pumped Nd:YAG laser.

PubMed

Liang, Dawei; Almeida, Joana

2011-12-19

The recent progress in solar-pumped laser with Fresnel lens and Cr:Nd:YAG ceramic medium has revitalized solar laser researches, revealing a promising future for renewable reduction of magnesium from magnesium oxide. Here we show a big advance in solar laser collection efficiency by utilizing an economical Fresnel lens and a most widely used Nd:YAG single-crystal rod. The incoming solar radiation from the sun is focused by a 0.9 m diameter Fresnel lens. A dielectric totally internally reflecting secondary concentrator is employed to couple the concentrated solar radiation from the focal zone to a 4 mm diameter Nd:YAG rod within a conical pumping cavity. 12.3 W cw laser power is produced, corresponding to 19.3 W/m(2) collection efficiency, which is 2.9 times larger than the previous results with Nd:YAG single-crystal medium. Record-high slope efficiency of 3.9% is also registered. Laser beam quality is considerably improved by pumping a 3 mm diameter Nd:YAG rod.

A novel sputtered Pd mesh architecture as an advanced electrocatalyst for highly efficient hydrogen production

NASA Astrophysics Data System (ADS)

de Lucas-Consuegra, Antonio; de la Osa, Ana R.; Calcerrada, Ana B.; Linares, José J.; Horwat, David

2016-07-01

This study reports the preparation, characterization and testing of a sputtered Pd mesh-like anode as an advanced electrocatalyst for H2 production from alkaline ethanol solutions in an Alkaline Membrane Electrolyzer (AEM). Pd anodic catalyst is prepared by magnetron sputtering technique onto a microfiber carbon paper support. Scanning Electron Microscopy images reveal that the used preparation technique enables to cover the surface of the carbon microfibers exposed to the Pd target, leading to a continuous network that also maintains part of the original carbon paper macroporosity. Such novel anodic architecture (organic binder free) presents an excellent electro-chemical performance, with a maximum current density of 700 mA cm-2 at 1.3 V, and, concomitantly, a large H2 production rate with low energy requirement compared to water electrolysis. Potassium hydroxide emerges as the best electrolyte, whereas temperature exerts the expected promotional effect up to 90 °C. On the other hand, a 1 mol L-1 ethanol solution is enough to guarantee an efficient fuel supply without any mass transfer limitation. The proposed system also demonstrates to remain stable over 150 h of operation along five consecutives cycles, producing highly pure H2 (99.999%) at the cathode and potassium acetate as the main anodic product.

High Efficiency, Low Emission Refrigeration System

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fricke, Brian A.; Sharma, Vishaldeep

Supermarket refrigeration systems account for approximately 50% of supermarket energy use, placing this class of equipment among the highest energy consumers in the commercial building domain. In addition, the commonly used refrigeration system in supermarket applications is the multiplex direct expansion (DX) system, which is prone to refrigerant leaks due to its long lengths of refrigerant piping. This leakage reduces the efficiency of the system and increases the impact of the system on the environment. The high Global Warming Potential (GWP) of the hydrofluorocarbon (HFC) refrigerants commonly used in these systems, coupled with the large refrigerant charge and the highmore » refrigerant leakage rates leads to significant direct emissions of greenhouse gases into the atmosphere. Methods for reducing refrigerant leakage and energy consumption are available, but underutilized. Further work needs to be done to reduce costs of advanced system designs to improve market utilization. In addition, refrigeration system retrofits that result in reduced energy consumption are needed since the majority of applications address retrofits rather than new stores. The retrofit market is also of most concern since it involves large-volume refrigerant systems with high leak rates. Finally, alternative refrigerants for new and retrofit applications are needed to reduce emissions and reduce the impact on the environment. The objective of this Collaborative Research and Development Agreement (CRADA) between the Oak Ridge National Laboratory and Hill Phoenix is to develop a supermarket refrigeration system that reduces greenhouse gas emissions and has 25 to 30 percent lower energy consumption than existing systems. The outcomes of this project will include the design of a low emission, high efficiency commercial refrigeration system suitable for use in current U.S. supermarkets. In addition, a prototype low emission, high efficiency supermarket refrigeration system will be produced

A low-power, high-efficiency Ka-band TWTA

NASA Technical Reports Server (NTRS)

Curren, A. N.; Dayton, J. A., Jr.; Palmer, R. W.; Force, D. A.; Tamashiro, R. N.; Wilson, J. F.; Dombro, L.; Harvey, W. L.

1991-01-01

A NASA-sponsored program is described for developing a high-efficiency low-power TWTA operating at 32 GHz and meeting the requirements for the Cassini Mission to study Saturn. The required RF output power of the helix TWT is 10 watts, while the dc power from the spacecraft is limited to about 30 watts. The performance level permits the transmission to earth of all mission data. Several novel technologies are incorporated into the TWT to achieve this efficiency including an advanced dynamic velocity taper characterized by a nonlinear reduction in pitch in the output helix section and a multistage depressed collector employing copper electrodes treated for secondary electron-emission suppression. Preliminary program results are encouraging: RF output power of 10.6 watts is obtained at 14-mA beam current and 5.2-kV helix voltage with overall TWT efficiency exceeding 40 percent.

A low-power, high-efficiency Ka-band TWTA

NASA Astrophysics Data System (ADS)

Curren, A. N.; Dayton, J. A., Jr.; Palmer, R. W.; Force, D. A.; Tamashiro, R. N.; Wilson, J. F.; Dombro, L.; Harvey, W. L.

1991-11-01

A NASA-sponsored program is described for developing a high-efficiency low-power TWTA operating at 32 GHz and meeting the requirements for the Cassini Mission to study Saturn. The required RF output power of the helix TWT is 10 watts, while the dc power from the spacecraft is limited to about 30 watts. The performance level permits the transmission to earth of all mission data. Several novel technologies are incorporated into the TWT to achieve this efficiency including an advanced dynamic velocity taper characterized by a nonlinear reduction in pitch in the output helix section and a multistage depressed collector employing copper electrodes treated for secondary electron-emission suppression. Preliminary program results are encouraging: RF output power of 10.6 watts is obtained at 14-mA beam current and 5.2-kV helix voltage with overall TWT efficiency exceeding 40 percent.

Design and overall performance of four highly loaded, high speed inlet stages for an advanced high-pressure-ratio core compressor

NASA Technical Reports Server (NTRS)

Reid, L.; Moore, R. D.

1978-01-01

The detailed design and overall performances of four inlet stages for an advanced core compressor are presented. These four stages represent two levels of design total pressure ratio (1.82 and 2.05), two levels of rotor aspect ratio (1.19 and 1.63), and two levels of stator aspect ratio (1.26 and 1.78). The individual stages were tested over the stable operating flow range at 70, 90, and 100 percent of design speeds. The performances of the low aspect ratio configurations were substantially better than those of the high aspect ratio configurations. The two low aspect ratio configurations achieved peak efficiencies of 0.876 and 0.872 and corresponding stage efficiencies of 0.845 and 0.840. The high aspect ratio configurations achieved peak ratio efficiencies of 0.851 and 0.849 and corresponding stage efficiencies of 0.821 and 0.831.

Mutual physiological genetic mechanism of plant high water use efficiency and nutrition use efficiency.

PubMed

Cao, Hong-Xing; Zhang, Zheng-Bin; Xu, Ping; Chu, Li-Ye; Shao, Hong-Bo; Lu, Zhao-Hua; Liu, Jun-Hong

2007-05-15

Water deficiency and lower fertilizer utilization efficiency are major constraints of productivity and yield stability. Improvements of crop water use efficiency (WUE) and nutrient use efficiency (NUE) is becoming an important objective in crop breeding. With the introduction of new physiological and biological approaches, we can better understand the mutual genetics mechanism of high use efficiency of water and nutrient. Much work has been done in past decades mainly including the interactions between different fertilizers and water influences on root characteristics and crop growth. Fertilizer quantity and form were regulated in order to improve crop WUE. The crop WUE and NUE shared the same increment tendency during evolution process; some genes associated with WUE and NUE have been precisely located and marked on the same chromosomes, some genes related to WUE and NUE have been cloned and transferred into wheat and rice and other plants, they can enhance water and nutrient use efficiency. The proteins transporting nutrient and water were identified such as some water channel proteins. The advance on the mechanism of higher water and nutrient use efficiency in crop was reviewed in this article, and it could provide some useful information for further research on WUE and NUE in crop.

Surface nanodroplets for highly efficient liquid-liquid microextraction

NASA Astrophysics Data System (ADS)

Li, Miaosi; Lu, Ziyang; Yu, Haitao; Zhang, Xuehua

2016-11-01

Nanoscale droplets on a substrate are an essential element for a wide range of applications, such as laboratory-on-chip devices, simple and highly efficient miniaturized reactors for concentrating products, high-throughput single-bacteria or single-biomolecular analysis, encapsulation, and high-resolution imaging techniques. The solvent exchange process is a simple bottom-up approach for producing droplets at solid-liquid interfaces that are only several tens to hundreds of nanometers in height, or a few femtoliters in volume Oil nanodroplets can be produced on a substrate by solvent exchange in which a good solvent of oil is displaced by a poor solvent. Our previous work has significantly advanced understanding of the principle of solvent exchange, and the droplet size can be well-controlled by several parameters, including flow rates, flow geometry, gravitational effect and composition of solutions. In this work, we studied the microextraction effect of surface nanodroplets. Oil nanodroplets have been demonstrated to provide highly-efficient liquid-liquid microextraction of hydrophobic solute in a highly diluted solution. This effect proved the feasibility of nanodroplets as a platform for preconcentrating compounds for in situ highly sensitive microanalysis without further separation. Also the long lifetime and temporal stability of surface nanodroplets allow for some long-term extraction process and extraction without addition of stabilisers.

Advanced techniques and technology for efficient data storage, access, and transfer

NASA Technical Reports Server (NTRS)

Rice, Robert F.; Miller, Warner

1991-01-01

Advanced techniques for efficiently representing most forms of data are being implemented in practical hardware and software form through the joint efforts of three NASA centers. These techniques adapt to local statistical variations to continually provide near optimum code efficiency when representing data without error. Demonstrated in several earlier space applications, these techniques are the basis of initial NASA data compression standards specifications. Since the techniques clearly apply to most NASA science data, NASA invested in the development of both hardware and software implementations for general use. This investment includes high-speed single-chip very large scale integration (VLSI) coding and decoding modules as well as machine-transferrable software routines. The hardware chips were tested in the laboratory at data rates as high as 700 Mbits/s. A coding module's definition includes a predictive preprocessing stage and a powerful adaptive coding stage. The function of the preprocessor is to optimally process incoming data into a standard form data source that the second stage can handle.The built-in preprocessor of the VLSI coder chips is ideal for high-speed sampled data applications such as imaging and high-quality audio, but additionally, the second stage adaptive coder can be used separately with any source that can be externally preprocessed into the 'standard form'. This generic functionality assures that the applicability of these techniques and their recent high-speed implementations should be equally broad outside of NASA.

ADX: a high field, high power density, Advanced Divertor test eXperiment

NASA Astrophysics Data System (ADS)

Vieira, R.; Labombard, B.; Marmar, E.; Irby, J.; Shiraiwa, S.; Terry, J.; Wallace, G.; Whyte, D. G.; Wolfe, S.; Wukitch, S.; ADX Team

2014-10-01

The MIT PSFC and collaborators are proposing an advanced divertor experiment (ADX) - a tokamak specifically designed to address critical gaps in the world fusion research program on the pathway to FNSF/DEMO. This high field (6.5 tesla, 1.5 MA), high power density (P/S ~ 1.5 MW/m2) facility would utilize Alcator magnet technology to test innovative divertor concepts for next-step DT fusion devices (FNSF, DEMO) at reactor-level boundary plasma pressures and parallel heat flux densities while producing high performance core plasma conditions. The experimental platform would also test advanced lower hybrid current drive (LHCD) and ion-cyclotron range of frequency (ICRF) actuators and wave physics at the plasma densities and magnetic field strengths of a DEMO, with the unique ability to deploy launcher structures both on the low-magnetic-field side and the high-field side - a location where energetic plasma-material interactions can be controlled and wave physics is most favorable for efficient current drive, heating and flow drive. This innovative experiment would perform plasma science and technology R&D necessary to inform the conceptual development and accelerate the readiness-for-deployment of FNSF/DEMO - in a timely manner, on a cost-effective research platform. Supported by DE-FC02-99ER54512.

High Efficiency Space Power Systems Project Advanced Space-Rated Batteries

NASA Technical Reports Server (NTRS)

Reid, Concha M.

2011-01-01

Case Western Reserve University (CWRU) has an agreement with China National Offshore Oil Corporation New Energy Investment Company, Ltd. (CNOOC), under the United States-China EcoPartnerships Framework, to create a bi-national entity seeking to develop technically feasible and economically viable solutions to energy and environmental issues. Advanced batteries have been identified as one of the initial areas targeted for collaborations. CWRU invited NASA Glenn Research Center (GRC) personnel from the Electrochemistry Branch to CWRU to discuss various aspects of advanced battery development as they might apply to this partnership. Topics discussed included: the process for the selection of a battery chemistry; the establishment of an integrated development program; project management/technical interactions; new technology developments; and synergies between batteries for automotive and space operations. Additional collaborations between CWRU and NASA GRC's Electrochemistry Branch were also discussed.

High-Efficiency Food Production in a Renewable Energy Based Micro-Grid

NASA Technical Reports Server (NTRS)

Bubenheim, David L.

2017-01-01

Controlled Environment Agriculture (CEA) systems can be used to produce high-quality, desirable food year round, and the fresh produce can positively contribute to the health and well being of residents in communities with difficult supply logistics. While CEA has many positive outcomes for a remote community, the associated high electric demands have prohibited widespread implementation in what is typically already a fully subscribed power generation and distribution system. Recent advances in CEA technologies as well as renewable power generation, storage, and micro-grid management are increasing system efficiency and expanding the possibilities for enhancing community supporting infrastructure without increasing demands for outside supplied fuels. We will present examples of how new lighting, nutrient delivery, and energy management and control systems can enable significant increases in food production efficiency while maintaining high yields in CEA.Examples from Alaskan communities where initial incorporation of renewable power generation, energy storage and grid management techniques have already reduced diesel fuel consumption for electric generation by more than 40 and expanded grid capacity will be presented. We will discuss how renewable power generation, efficient grid management to extract maximum community service per kW, and novel energy storage approaches can expand the food production, water supply, waste treatment, sanitation and other community support services without traditional increases of consumable fuels supplied from outside the community. These capabilities offer communities with a range of choices to enhance their communities. The examples represent a synergy of technology advancement efforts to develop sustainable community support systems for future space-based human habitats and practical implementation of infrastructure components to increase efficiency and enhance health and well-being in remote communities today and tomorrow.

Energy efficiency of high-rise buildings

NASA Astrophysics Data System (ADS)

Zhigulina, Anna Yu.; Ponomarenko, Alla M.

2018-03-01

The article is devoted to analysis of tendencies and advanced technologies in the field of energy supply and energy efficiency of tall buildings, to the history of the emergence of the concept of "efficiency" and its current interpretation. Also the article show the difference of evaluation criteria of the leading rating systems LEED and BREEAM. Authors reviewed the latest technologies applied in the construction of energy efficient buildings. Methodological approach to the design of tall buildings taking into account energy efficiency needs to include the primary energy saving; to seek the possibility of production and accumulation of alternative electric energy by converting energy from the sun and wind with the help of special technical devices; the application of regenerative technologies.

Building America Case Study: Simple Retrofit High-Efficiency Natural Gas Water Heater Field Test, Minneapolis, Minnesota

DOE Office of Scientific and Technical Information (OSTI.GOV)

T. Schirber, B. Schoenbauer

High-performance water heaters are typically more time consuming and costly to install in retrofit applications, making high-performance water heaters difficult to justify economically. However, recent advancements in high-performance water heaters have targeted the retrofit market, simplifying installations and reducing costs. Four high-efficiency natural gas water heaters designed specifically for retrofit applications were installed in single-family homes along with detailed monitoring systems to characterize their savings potential, their installed efficiencies, and their ability to meet household demands.

Selectively Modulating Triplet Exciton Formation in Host Materials for Highly Efficient Blue Electrophosphorescence.

PubMed

Li, Huanhuan; Bi, Ran; Chen, Ting; Yuan, Kai; Chen, Runfeng; Tao, Ye; Zhang, Hongmei; Zheng, Chao; Huang, Wei

2016-03-23

The concept of limiting the triplet exciton formation to fundamentally alleviate triplet-involved quenching effects is introduced to construct host materials for highly efficient and stable blue phosphorescent organic light-emitting diodes (PhOLEDs). The low triplet exciton formation is realized by small triplet exciton formation fraction and rate with high binding energy and high reorganization energy of triplet exciton. Demonstrated in two analogue molecules in conventional donor-acceptor molecule structure for bipolar charge injection and transport with nearly the same frontier orbital energy levels and triplet excited energies, the new concept host material shows significantly suppressed triplet exciton formation in the host to avoid quenching effects, leading to much improved device efficiencies and stabilities. The low-voltage-driving blue PhOLED devices exhibit maximum efficiencies of 43.7 cd A(-1) for current efficiency, 32.7 lm W(-1) for power efficiency, and 20.7% for external quantum efficiency with low roll-off and remarkable relative quenching effect reduction ratio up to 41%. Our fundamental solution for preventing quenching effects of long-lived triplet excitons provides exciting opportunities for fabricating high-performance devices using the advanced host materials with intrinsically small triplet exciton formation cross section.

The Consortium of Advanced Residential Buildings (CARB) - A Building America Energy Efficient Housing Partnership

DOE Office of Scientific and Technical Information (OSTI.GOV)

Robb Aldrich; Lois Arena; Dianne Griffiths

2010-12-31

This final report summarizes the work conducted by the Consortium of Advanced Residential Buildings (CARB) (http://www.carb-swa.com/), one of the 'Building America Energy Efficient Housing Partnership' Industry Teams, for the period January 1, 2008 to December 31, 2010. The Building America Program (BAP) is part of the Department of Energy (DOE), Energy Efficiency and Renewable Energy, Building Technologies Program (BTP). The long term goal of the BAP is to develop cost effective, production ready systems in five major climate zones that will result in zero energy homes (ZEH) that produce as much energy as they use on an annual basis bymore » 2020. CARB is led by Steven Winter Associates, Inc. with Davis Energy Group, Inc. (DEG), MaGrann Associates, and Johnson Research, LLC as team members. In partnership with our numerous builders and industry partners, work was performed in three primary areas - advanced systems research, prototype home development, and technical support for communities of high performance homes. Our advanced systems research work focuses on developing a better understanding of the installed performance of advanced technology systems when integrated in a whole-house scenario. Technology systems researched included: - High-R Wall Assemblies - Non-Ducted Air-Source Heat Pumps - Low-Load HVAC Systems - Solar Thermal Water Heating - Ventilation Systems - Cold-Climate Ground and Air Source Heat Pumps - Hot/Dry Climate Air-to-Water Heat Pump - Condensing Boilers - Evaporative condensers - Water Heating CARB continued to support several prototype home projects in the design and specification phase. These projects are located in all five program climate regions and most are targeting greater than 50% source energy savings over the Building America Benchmark home. CARB provided technical support and developed builder project case studies to be included in near-term Joule Milestone reports for the following community scale projects: - SBER Overlook at

Advanced chip designs and novel cooling techniques for brightness scaling of industrial, high power diode laser bars

NASA Astrophysics Data System (ADS)

Heinemann, S.; McDougall, S. D.; Ryu, G.; Zhao, L.; Liu, X.; Holy, C.; Jiang, C.-L.; Modak, P.; Xiong, Y.; Vethake, T.; Strohmaier, S. G.; Schmidt, B.; Zimer, H.

2018-02-01

The advance of high power semiconductor diode laser technology is driven by the rapidly growing industrial laser market, with such high power solid state laser systems requiring ever more reliable diode sources with higher brightness and efficiency at lower cost. In this paper we report simulation and experimental data demonstrating most recent progress in high brightness semiconductor laser bars for industrial applications. The advancements are in three principle areas: vertical laser chip epitaxy design, lateral laser chip current injection control, and chip cooling technology. With such improvements, we demonstrate disk laser pump laser bars with output power over 250W with 60% efficiency at the operating current. Ion implantation was investigated for improved current confinement. Initial lifetime tests show excellent reliability. For direct diode applications <1 um smile and >96% polarization are additional requirements. Double sided cooling deploying hard solder and optimized laser design enable single emitter performance also for high fill factor bars and allow further power scaling to more than 350W with 65% peak efficiency with less than 8 degrees slow axis divergence and high polarization.

Highly efficient organic light-emitting diodes with a quantum dot interfacial layer.

PubMed

Ryu, Seung Yoon; Hwang, Byoung Har; Park, Ki Wan; Hwang, Hyeon Seok; Sung, Jin Woo; Baik, Hong Koo; Lee, Chang Ho; Song, Seung Yong; Lee, Jun Yeob

2009-02-11

Advanced organic light-emitting diodes (OLEDs), based on a multiple structure, were achieved in combination with a quantum dot (QD) interfacial layer. The authors used core/shell CdSe/ZnS QDs passivated with trioctylphosphine oxide (TOPO) and TOPO-free QDs as interlayers. Multiple-structure OLEDs (MOLEDs) with TOPO-free QDs showed higher device efficiency because of a well-defined interfacial monolayer formation. Additionally, the three-unit MOLED showed high performance for device efficiency with double-structured QD interfacial layers due to the enhanced charge balance and recombination probability.

High-Efficiency Solar Thermal Vacuum Demonstration Completed for Refractive Secondary Concentrator

NASA Technical Reports Server (NTRS)

Wong, Wayne A.

2001-01-01

Common to many of the space applications that utilize solar thermal energy--such as electric power conversion, thermal propulsion, and furnaces--is a need for highly efficient, solar concentration systems. An effort is underway at the NASA Glenn Research Center to develop 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, the refractive secondary concentrator enables very high system concentration ratios (10,000 to 1) and very high temperatures (>2000 K). The innovative refractive secondary concentrator offers significant advantages over all other types of secondary concentrators. The refractive secondary offers the highest throughput efficiency, provides for flux tailoring, requires no active cooling, relaxes the pointing and tracking requirements of the primary concentrator, and enables very high system concentration ratios. This technology has broad applicability to any system that requires the conversion of solar energy to heat. Glenn initiated the development of the refractive secondary concentrator in support of Shooting Star, a solar thermal propulsion flight experiment, and continued the development in support of Space Solar Power.

Summary and recent results from the NASA advanced High Speed Propeller Research Program

NASA Technical Reports Server (NTRS)

Mitchell, G. A.; Mikkelson, D. C.

1982-01-01

Advanced high-speed propellers offer large performance improvements for aircraft that cruise in the Mach 0.7 to 0.8 speed regime. The current status of the NASA research program on high-speed propeller aerodynamics, acoustics, and aeroelastics is described. Recent wind tunnel results for five 8- to 10-blade advanced models are compared with analytical predictions. Test results show that blade sweep was important in achieving net efficiencies near 80 percent at Mach 0.8 and reducing near-field cruise noise by dB. Lifting line and lifting surface aerodynamic analysis codes are under development and some initial lifting line results are compared with propeller force and probe data. Some initial laser velocimeter measurements of the flow field velocities of an 8-bladed 45 deg swept propeller are shown. Experimental aeroelastic results indicate that cascade effects and blade sweep strongly affect propeller aeroelastic characteristics. Comparisons of propeller near-field noise data with linear acoustic theory indicate that the theory adequate predicts near-field noise for subsonic tip speeds but overpredicts the noise for supersonic tip speeds. Potential large gains in propeller efficiency of 7 to 11 percent at Mach 0.8 may be possible with advanced counter-rotation propellers.

Aggregation and morphology control enables multiple cases of high-efficiency polymer solar cells

PubMed Central

Liu, Yuhang; Zhao, Jingbo; Li, Zhengke; Mu, Cheng; Hu, Huawei; Jiang, Kui; Lin, Haoran; Ade, Harald; Yan, He

2014-01-01

Although the field of polymer solar cell has seen much progress in device performance in the past few years, several limitations are holding back its further development. For instance, current high-efficiency (>9.0%) cells are restricted to material combinations that are based on limited donor polymers and only one specific fullerene acceptor. Here we report the achievement of high-performance (efficiencies up to 10.8%, fill factors up to 77%) thick-film polymer solar cells for multiple polymer:fullerene combinations via the formation of a near-ideal polymer:fullerene morphology that contains highly crystalline yet reasonably small polymer domains. This morphology is controlled by the temperature-dependent aggregation behaviour of the donor polymers and is insensitive to the choice of fullerenes. The uncovered aggregation and design rules yield three high-efficiency (>10%) donor polymers and will allow further synthetic advances and matching of both the polymer and fullerene materials, potentially leading to significantly improved performance and increased design flexibility. PMID:25382026

High Efficiency Power Combining of Ka-Band TWTs for High Data Rate Communications

NASA Technical Reports Server (NTRS)

Wintucky, E. G.; Simons, R. N.; Vaden, K. R.; Lesny, G. G.; Glass, J. L.

2006-01-01

Future NASA deep space exploration missions are expected in some cases to require telecommunication systems capable of operating at very high data rates (potentially 1 Gbps or more) for the transmission back to Earth of large volumes of scientific data, which means high frequency transmitters with large bandwidth. Among the Ka band frequencies of interest are the present 500 MHz Deep Space Network (DSN) band of 31.8 to 32.3 GHz and a broader band at 37-38 GHz allocated for space science [1]. The large distances and use of practical antenna sizes dictate the need for high transmitter power of up to 1 kW or more. High electrical efficiency is also a requirement. The approach investigated by NASA GRC is a novel wave guide power combiner architecture based on a hybrid magic-T junction for combining the power output from multiple TWTs [1,2]. This architecture was successfully demonstrated and is capable of both high efficiency (90-95%, depending on frequency) and high data rate transmission (up to 622 Mbps) in a two-way power combiner circuit for two different pairs of Ka band TWTs at two different frequency bands. One pair of TWTs, tested over a frequency range of 29.1 to 29.6 GHz, consisted of two 110-115W TWTs previously used in uplink data transmission evaluation terminals in the NASA Advanced Communications Technology Satellite (ACTS) program [1,2]. The second pair was two 100W TWTs (Boeing 999H) designed for high efficiency operation (greater than 55%) over the DSN frequency band of 31.8 to 32.3 GHz [3]. The presentation will provide a qualitative description of the wave guide circuit, results for power combining and data transmission measurements, and results of computer modeling of the magic-T and alternative hybrid junctions for improvements in efficiency and power handling capability. The power combiner results presented here are relevant not only to NASA deep space exploration missions, but also to other U.S. Government agency programs.

Advanced optical systems for ultra high energy cosmic rays detection

NASA Astrophysics Data System (ADS)

Gambicorti, L.; Pace, E.; Mazzinghi, P.

2017-11-01

A new advanced optical system is proposed and analysed in this work with the purpose to improve the photons collection efficiency of Multi-AnodePhotoMultipliers (MAPMT) detectors, which will be used to cover large focal surface of instruments dedicated to the Ultra High Energy Cosmic Rays (UHECRs, above 1019eV) and Ultra High Energy Neutrino (UHEN) detection. The employment of the advanced optical system allows to focus all photons inside the sensitive area of detectors and to improve the signal-to-noise ratios in the wavelength range of interest (300-400nm), thus coupling imaging and filtering capability. Filter is realised with a multilayer coating to reach high transparency in UV range and with a sharp cut-off outside. In this work the applications on different series of PMTs have been studied and results of simulations are shown. First prototypes have been realised. Finally, this paper proposes another class of adapters to be optically coupled on each pixel of MAPMT detector selected, consisting of non-imaging concentrators as Winston cones.

Application of an efficient hybrid scheme for aeroelastic analysis of advanced propellers

NASA Technical Reports Server (NTRS)

Srivastava, R.; Sankar, N. L.; Reddy, T. S. R.; Huff, D. L.

1989-01-01

An efficient 3-D hybrid scheme is applied for solving Euler equations to analyze advanced propellers. The scheme treats the spanwise direction semi-explicitly and the other two directions implicitly, without affecting the accuracy, as compared to a fully implicit scheme. This leads to a reduction in computer time and memory requirement. The calculated power coefficients for two advanced propellers, SR3 and SR7L, and various advanced ratios showed good correlation with experiment. Spanwise distribution of elemental power coefficient and steady pressure coefficient differences also showed good agreement with experiment. A study of the effect of structural flexibility on the performance of the advanced propellers showed that structural deformation due to centrifugal and aero loading should be included for better correlation.

Thin film CdTe based neutron detectors with high thermal neutron efficiency and gamma rejection for security applications

NASA Astrophysics Data System (ADS)

Smith, L.; Murphy, J. W.; Kim, J.; Rozhdestvenskyy, S.; Mejia, I.; Park, H.; Allee, D. R.; Quevedo-Lopez, M.; Gnade, B.

2016-12-01

Solid-state neutron detectors offer an alternative to 3He based detectors, but suffer from limited neutron efficiencies that make their use in security applications impractical. Solid-state neutron detectors based on single crystal silicon also have relatively high gamma-ray efficiencies that lead to false positives. Thin film polycrystalline CdTe based detectors require less complex processing with significantly lower gamma-ray efficiencies. Advanced geometries can also be implemented to achieve high thermal neutron efficiencies competitive with silicon based technology. This study evaluates these strategies by simulation and experimentation and demonstrates an approach to achieve >10% intrinsic efficiency with <10-6 gamma-ray efficiency.

High Temperature Solid Lubricant Materials for Heavy Duty and Advanced Heat Engines

NASA Technical Reports Server (NTRS)

Dellacorte, C.; Wood, J. C.

1994-01-01

Advanced engine designs incorporate higher mechanical and thermal loading to achieve efficiency improvements. This approach often leads to higher operating temperatures of critical sliding elements (e.g. piston ring/cylinder wall contacts and valve guides) which compromise the use of conventional and even advanced synthetic liquid lubricants. For these applications solid lubricants must be considered. Several novel solid lubricant composites and coatings designated PS/PM200 have been employed to dry and marginally oil lubricated contacts in advanced heat engines. These applications include cylinder kits of heavy duty diesels, and high temperature Stirling engines, sidewall seals of rotary engines, and various exhaust valve and exhaust component applications. This paper describes the tribological and thermophysical properties of these tribomaterials and reviews the results of applying them to engine applications. Other potential tribological materials and applications are also discussed with particular emphasis on heavy duty and advanced heat engines.

Advanced high temperature heat flux sensors

NASA Technical Reports Server (NTRS)

Atkinson, W.; Hobart, H. F.; Strange, R. R.

1983-01-01

To fully characterize advanced high temperature heat flux sensors, calibration and testing is required at full engine temperature. This required the development of unique high temperature heat flux test facilities. These facilities were developed, are in place, and are being used for advanced heat flux sensor development.

ADX: a high field, high power density, advanced divertor and RF tokamak

NASA Astrophysics Data System (ADS)

LaBombard, B.; Marmar, E.; Irby, J.; Terry, J. L.; Vieira, R.; Wallace, G.; Whyte, D. G.; Wolfe, S.; Wukitch, S.; Baek, S.; Beck, W.; Bonoli, P.; Brunner, D.; Doody, J.; Ellis, R.; Ernst, D.; Fiore, C.; Freidberg, J. P.; Golfinopoulos, T.; Granetz, R.; Greenwald, M.; Hartwig, Z. S.; Hubbard, A.; Hughes, J. W.; Hutchinson, I. H.; Kessel, C.; Kotschenreuther, M.; Leccacorvi, R.; Lin, Y.; Lipschultz, B.; Mahajan, S.; Minervini, J.; Mumgaard, R.; Nygren, R.; Parker, R.; Poli, F.; Porkolab, M.; Reinke, M. L.; Rice, J.; Rognlien, T.; Rowan, W.; Shiraiwa, S.; Terry, D.; Theiler, C.; Titus, P.; Umansky, M.; Valanju, P.; Walk, J.; White, A.; Wilson, J. R.; Wright, G.; Zweben, S. J.

2015-05-01

The MIT Plasma Science and Fusion Center and collaborators are proposing a high-performance Advanced Divertor and RF tokamak eXperiment (ADX)—a tokamak specifically designed to address critical gaps in the world fusion research programme on the pathway to next-step devices: fusion nuclear science facility (FNSF), fusion pilot plant (FPP) and/or demonstration power plant (DEMO). This high-field (⩾6.5 T, 1.5 MA), high power density facility (P/S ˜ 1.5 MW m-2) will test innovative divertor ideas, including an ‘X-point target divertor’ concept, at the required performance parameters—reactor-level boundary plasma pressures, magnetic field strengths and parallel heat flux densities entering into the divertor region—while simultaneously producing high-performance core plasma conditions that are prototypical of a reactor: equilibrated and strongly coupled electrons and ions, regimes with low or no torque, and no fuelling from external heating and current drive systems. Equally important, the experimental platform will test innovative concepts for lower hybrid current drive and ion cyclotron range of frequency actuators with the unprecedented ability to deploy launch structures both on the low-magnetic-field side and the high-magnetic-field side—the latter being a location where energetic plasma-material interactions can be controlled and favourable RF wave physics leads to efficient current drive, current profile control, heating and flow drive. This triple combination—advanced divertors, advanced RF actuators, reactor-prototypical core plasma conditions—will enable ADX to explore enhanced core confinement physics, such as made possible by reversed central shear, using only the types of external drive systems that are considered viable for a fusion power plant. Such an integrated demonstration of high-performance core-divertor operation with steady-state sustainment would pave the way towards an attractive pilot plant, as envisioned in the ARC concept

High-Efficiency Food Production in a Renewable Energy Based Micro-Grid Power System

NASA Technical Reports Server (NTRS)

Bubenheim, David; Meiners, Dennis

2016-01-01

Controlled Environment Agriculture (CEA) systems can be used to produce high-quality, desirable food year round, and the fresh produce can positively contribute to the health and well being of residents in communities with difficult supply logistics. While CEA has many positive outcomes for a remote community, the associated high electric demands have prohibited widespread implementation in what is typically already a fully subscribed power generation and distribution system. Recent advances in CEA technologies as well as renewable power generation, storage, and micro-grid management are increasing system efficiency and expanding the possibilities for enhancing community supporting infrastructure without increasing demands for outside supplied fuels. We will present examples of how new lighting, nutrient delivery, and energy management and control systems can enable significant increases in food production efficiency while maintaining high yields in CEA. Examples from Alaskan communities where initial incorporation of renewable power generation, energy storage and grid management techniques have already reduced diesel fuel consumption for electric generation by more than 40% and expanded grid capacity will be presented. We will discuss how renewable power generation, efficient grid management to extract maximum community service per kW, and novel energy storage approaches can expand the food production, water supply, waste treatment, sanitation and other community support services without traditional increases of consumable fuels supplied from outside the community. These capabilities offer communities with a range of choices to enhance their communities. The examples represent a synergy of technology advancement efforts to develop sustainable community support systems for future space-based human habitats and practical implementation of infrastructure components to increase efficiency and enhance health and well being in remote communities today and tomorrow.

Light-induced lattice expansion leads to high-efficiency perovskite solar cells.

PubMed

Tsai, Hsinhan; Asadpour, Reza; Blancon, Jean-Christophe; Stoumpos, Constantinos C; Durand, Olivier; Strzalka, Joseph W; Chen, Bo; Verduzco, Rafael; Ajayan, Pulickel M; Tretiak, Sergei; Even, Jacky; Alam, Muhammad Ashraf; Kanatzidis, Mercouri G; Nie, Wanyi; Mohite, Aditya D

2018-04-06

Light-induced structural dynamics plays a vital role in the physical properties, device performance, and stability of hybrid perovskite-based optoelectronic devices. We report that continuous light illumination leads to a uniform lattice expansion in hybrid perovskite thin films, which is critical for obtaining high-efficiency photovoltaic devices. Correlated, in situ structural and device characterizations reveal that light-induced lattice expansion benefits the performances of a mixed-cation pure-halide planar device, boosting the power conversion efficiency from 18.5 to 20.5%. The lattice expansion leads to the relaxation of local lattice strain, which lowers the energetic barriers at the perovskite-contact interfaces, thus improving the open circuit voltage and fill factor. The light-induced lattice expansion did not compromise the stability of these high-efficiency photovoltaic devices under continuous operation at full-spectrum 1-sun (100 milliwatts per square centimeter) illumination for more than 1500 hours. Copyright © 2018 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works.

More Efficient Power Conversion for EVs: Gallium-Nitride Advanced Power Semiconductor and Packaging

DOE Office of Scientific and Technical Information (OSTI.GOV)

None

2010-02-01

Broad Funding Opportunity Announcement Project: Delphi is developing power converters that are smaller and more energy efficient, reliable, and cost-effective than current power converters. Power converters rely on power transistors which act like a very precisely controlled on-off switch, controlling the electrical energy flowing through an electrical circuit. Most power transistors today use silicon (Si) semiconductors. However, Delphi is using semiconductors made with a thin layer of gallium-nitride (GaN) applied on top of the more conventional Si material. The GaN layer increases the energy efficiency of the power transistor and also enables the transistor to operate at much higher temperatures,more » voltages, and power-density levels compared to its Si counterpart. Delphi is packaging these high-performance GaN semiconductors with advanced electrical connections and a cooling system that extracts waste heat from both sides of the device to further increase the device’s efficiency and allow more electrical current to flow through it. When combined with other electronic components on a circuit board, Delphi’s GaN power transistor package will help improve the overall performance and cost-effectiveness of HEVs and EVs.« less

Wind tunnel performance results of swirl recovery vanes as tested with an advanced high speed propeller

NASA Technical Reports Server (NTRS)

Gazzaniga, John A.; Rose, Gayle E.

1992-01-01

Tests of swirl recovery vanes designed for use in conjunction with advanced high speed propellers were carried out at the NASA Lewis Research Center. The eight bladed 62.23 cm vanes were tested with a 62.23 cm SR = 7A high speed propeller in the NASA Lewis 2.44 x 1.83 m Supersonic Wind Tunnel for a Mach number range of 0.60 to 0.80. At the design operating condition for cruise of Mach 0.80 at an advance ratio of 3.26, the vane contribution to the total efficiency approached 2 percent. At lower off-design Mach numbers, the vane efficiency is even higher, approaching 4.5 percent for the Mach 0.60 condition. Use of the swirl recovery vanes essentially shifts the peak of the high speed propeller efficiency to a higher operating speed. This allows a greater degree of freedom in the selection of rpm over a wider operating range. Another unique result of the swirl recovery vane configuration is their essentially constant torque split between the propeller and the swirl vanes over a wide range of operating conditions for the design vane angle.

Metasurface integrated high energy efficient and high linearly polarized InGaN/GaN light emitting diode.

PubMed

Wang, Miao; Xu, Fuyang; Lin, Yu; Cao, Bing; Chen, Linghua; Wang, Chinhua; Wang, Jianfeng; Xu, Ke

2017-07-06

We proposed and demonstrated an integrated high energy efficient and high linearly polarized InGaN/GaN green LED grown on (0001) oriented sapphire with combined metasurface polarizing converter and polarizer system. It is different from those conventional polarized light emissions generated with plasmonic metallic grating in which at least 50% high energy loss occurs inherently due to high reflection of the transverse electric (TE) component of an electric field. A reflecting metasurface, with a two dimensional elliptic metal cylinder array (EMCA) that functions as a half-wave plate, was integrated at the bottom of a LED such that the back-reflected TE component, that is otherwise lost by a dielectric/metal bi-layered wire grids (DMBiWG) polarizer on the top emitting surface of the LED, can be converted to desired transverse magnetic (TM) polarized emission after reflecting from the metasurface. This significantly enhances the polarized light emission efficiency. Experimental results show that extraction efficiency of the polarized emission can be increased by 40% on average in a wide angle of ±60° compared to that with the naked bottom of sapphire substrate, or 20% compared to reflecting Al film on the bottom of a sapphire substrate. An extinction ratio (ER) of average value 20 dB within an angle of ±60° can be simultaneously obtained directly from an InGaN/GaN LED. Our results show the possibility of simultaneously achieving a high degree of polarization and high polarization extraction efficiency at the integrated device level. This advances the field of GaN LED toward energy efficiency, multi-functional applications in illumination, display, medicine, and light manipulation.

Advanced Boost System Developing for High EGR Applications

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sun, Harold

2012-09-30

To support industry efforts of clean and efficient internal combustion engine development for passenger and commercial applications • This program focuses on turbocharger improvement for medium and light duty diesel applications, from complete system optimization percepective to enable commercialization of advanced diesel combustion technologies, such as HCCI/LTC. • Improve combined turbocharger efficiency up to 10% or fuel economy by 3% on FTP cycle at Tier II Bin 5 emission level.

Noise impact of advanced high lift systems

NASA Technical Reports Server (NTRS)

Elmer, Kevin R.; Joshi, Mahendra C.

1995-01-01

The impact of advanced high lift systems on aircraft size, performance, direct operating cost and noise were evaluated for short-to-medium and medium-to-long range aircraft with high bypass ratio and very high bypass ratio engines. The benefit of advanced high lift systems in reducing noise was found to be less than 1 effective-perceived-noise decibel level (EPNdB) when the aircraft were sized to minimize takeoff gross weight. These aircraft did, however, have smaller wings and lower engine thrusts for the same mission than aircraft with conventional high lift systems. When the advanced high lift system was implemented without reducing wing size and simultaneously using lower flap angles that provide higher L/D at approach a cumulative noise reduction of as much as 4 EPNdB was obtained. Comparison of aircraft configurations that have similar approach speeds showed cumulative noise reduction of 2.6 EPNdB that is purely the result of incorporating advanced high lift system in the aircraft design.

Advanced Modified High Performance Synthetic Jet Actuator with Curved Chamber

NASA Technical Reports Server (NTRS)

Xu, Tian-Bing (Inventor); Su, Ji (Inventor); Jiang, Xiaoning (Inventor)

2014-01-01

The advanced modified high performance synthetic jet actuator with optimized curvature shape chamber (ASJA-M) is a synthetic jet actuator (SJA) with a lower volume reservoir or chamber. A curved chamber is used, instead of the conventional cylinder chamber, to reduce the dead volume of the jet chamber and increase the efficiency of the synthetic jet actuator. The shape of the curvature corresponds to the maximum displacement (deformation) profile of the electroactive diaphragm. The jet velocity and mass flow rate for the ASJA-M will be several times higher than conventional piezoelectric actuators.

Maximizing coupling-efficiency of high-power diode lasers utilizing hybrid assembly technology

NASA Astrophysics Data System (ADS)

Zontar, D.; Dogan, M.; Fulghum, S.; Müller, T.; Haag, S.; Brecher, C.

2015-03-01

In this paper, we present hybrid assembly technology to maximize coupling efficiency for spatially combined laser systems. High quality components, such as center-turned focusing units, as well as suitable assembly strategies are necessary to obtain highest possible output ratios. Alignment strategies are challenging tasks due to their complexity and sensitivity. Especially in low-volume production fully automated systems are economically at a disadvantage, as operator experience is often expensive. However reproducibility and quality of automatically assembled systems can be superior. Therefore automated and manual assembly techniques are combined to obtain high coupling efficiency while preserving maximum flexibility. The paper will describe necessary equipment and software to enable hybrid assembly processes. Micromanipulator technology with high step-resolution and six degrees of freedom provide a large number of possible evaluation points. Automated algorithms are necess ary to speed-up data gathering and alignment to efficiently utilize available granularity for manual assembly processes. Furthermore, an engineering environment is presented to enable rapid prototyping of automation tasks with simultaneous data ev aluation. Integration with simulation environments, e.g. Zemax, allows the verification of assembly strategies in advance. Data driven decision making ensures constant high quality, documents the assembly process and is a basis for further improvement. The hybrid assembly technology has been applied on several applications for efficiencies above 80% and will be discussed in this paper. High level coupling efficiency has been achieved with minimized assembly as a result of semi-automated alignment. This paper will focus on hybrid automation for optimizing and attaching turning mirrors and collimation lenses.

High efficiency solar cells for concentrator systems: silicon or multi-junction?

NASA Astrophysics Data System (ADS)

Slade, Alexander; Stone, Kenneth W.; Gordon, Robert; Garboushian, Vahan

2005-08-01

Amonix has become the first company to begin production of high concentration silicon solar cells where volumes are over 10 MW/year. Higher volumes are available due to the method of manufacture; Amonix solely uses semiconductor foundries for solar cell production. In the previous years of system and cell field testing, this method of manufacturing enabled Amonix to maintain a very low overhead while incurring a high cost for the solar cell. However, recent simplifications to the solar cell processing sequence resulted in cost reduction and increased yield. This new process has been tested by producing small qualities in very short time periods, enabling a simulation of high volume production. Results have included over 90% wafer yield, up to 100% die yield and world record performance (η =27.3%). This reduction in silicon solar cell cost has increased the required efficiency for multi-junction concentrator solar cells to be competitive / advantageous. Concentrator systems are emerging as a low-cost, high volume option for solar-generated electricity due to the very high utilization of the solar cell, leading to a much lower $/Watt cost of a photovoltaic system. Parallel to this is the onset of alternative solar cell technologies, such as the very high efficiency multi-junction solar cells developed at NREL over the last two decades. The relatively high cost of these type of solar cells has relegated their use to non-terrestrial applications. However, recent advancements in both multi-junction concentrator cell efficiency and their stability under high flux densities has made their large-scale terrestrial deployment significantly more viable. This paper presents Amonix's experience and testing results of both high-efficiency silicon rear-junction solar cells and multi-junction solar cells made for concentrated light operation.

[Tobacco--a highly efficient producer of vaccines].

PubMed

Budzianowski, Jaromir

2010-01-01

Along with the depreciation of tobacco as a source of nicotine-containing commercial products, the increase of its appreciation as a potential producer of recombinant therapeutical proteins can be observed. Two species of tobacco--Nicotiana tabacum L. and N. benthamiana are easily grown by well established methods of field or green-house cultivation or cell culture, yield high biomass and soluble protein content, can be easily transformed by several methods and are not food for humans or feed for animals. Expression of foreign proteins, including vaccines, can be achieved in those plants either through stable transformation of nuclear or plastid (chloroplast) genomes or by transient transformation using infection with plant virus or bacteria--Agrobacterium tumefaciens (agroinfiltration). The most advanced mode of agrofiltration termed magnifection, which combines benefits of virus and Agrobacterium and depends on using Agrobacterium with viral pro-vectors, enables high-yield and rapid expression of therapeutical proteins, even in a few days, and can be employed on an industrial scale. Expression of many antigenic proteins, which may serve as antiviral, antibacterial, antiprotozoan and anticancer vaccines, and additionally a few autoantigens designed for the treatment of autoimunogenic diseases, like diabetes, have been achieved in tobacco. To date, a vaccine against Newcastle virus disease in poultry produced by tobacco cell culture has been approved for commercial application and several other vaccines are in advanced stage of development. The possibility of a high-level production of vaccines in tobacco against pandemic influenza or anthrax and plague due to a bioterroristic attack, as well as of individualised anticancer vaccines against non-Hodgkin's lymphoma (NHL) in a much shorter period of time than by traditional methods became realistic and hence caused increased interest in tobacco as a high-efficient producer of vaccines not only of specialistic

Increased collection efficiency of LIFI high intensity electrodeless light source

NASA Astrophysics Data System (ADS)

Hafidi, Abdeslam; DeVincentis, Marc; Duelli, Markus; Gilliard, Richard

2008-02-01

Recently, RF driven electrodeless high intensity light sources have been implemented successfully in the projection display systems for HDTV and videowall applications. This paper presents advances made in the RF waveguide and electric field concentrator structures with the purpose of reducing effective arc size and increasing light collection. In addition, new optical designs are described that further improve system efficiency. The results of this work demonstrate that projection system light throughput is increased relative to previous implementations and performance is optimized for home theater and other front projector applications that maintain multi-year lifetime without re-lamping, complete spectral range, fast start times and high levels of dynamic contrast due to dimming flexibility in the light source system.

Energy Efficient Engine: High-pressure compressor test hardware detailed design report

NASA Technical Reports Server (NTRS)

Howe, David C.; Marchant, R. D.

1988-01-01

The objective of the NASA Energy Efficient Engine program is to identify and verify the technology required to achieve significant reductions in fuel consumption and operating cost for future commercial gas turbine engines. The design and analysis is documented of the high pressure compressor which was tested as part of the Pratt and Whitney effort under the Energy Efficient Engine program. This compressor was designed to produce a 14:1 pressure ratio in ten stages with an adiabatic efficiency of 88.2 percent in the flight propulsion system. The corresponding expected efficiency for the compressor component test rig is 86.5 percent. Other performance goals are a surge margin of 20 percent, a corrected flow rate of 35.2 kg/sec (77.5 lb/sec), and a life of 20,000 missions and 30,000 hours. Low loss, highly loaded airfoils are used to increase efficiency while reducing the parts count. Active clearance control and case trenches in abradable strips over the blade tips are included in the compressor component design to further increase the efficiency potential. The test rig incorporates variable geometry stator vanes in all stages to permit maximum flexibility in developing stage-to-stage matching. This provision precluded active clearance control on the rear case of the test rig. Both the component and rig designs meet or exceed design requirements with the exception of life goals, which will be achievable with planned advances in materials technology.

High-Performance Computing Data Center Water Usage Efficiency |

Science.gov Websites

cooler-an advanced dry cooler that uses refrigerant in a passive cycle to dissipate heat-was installed at efficiency-using wet cooling when it's hot and dry cooling when it's not. Learn more about NREL's partnership

A fully-implicit high-order system thermal-hydraulics model for advanced non-LWR safety analyses

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hu, Rui

An advanced system analysis tool is being developed for advanced reactor safety analysis. This paper describes the underlying physics and numerical models used in the code, including the governing equations, the stabilization schemes, the high-order spatial and temporal discretization schemes, and the Jacobian Free Newton Krylov solution method. The effects of the spatial and temporal discretization schemes are investigated. Additionally, a series of verification test problems are presented to confirm the high-order schemes. Furthermore, it is demonstrated that the developed system thermal-hydraulics model can be strictly verified with the theoretical convergence rates, and that it performs very well for amore » wide range of flow problems with high accuracy, efficiency, and minimal numerical diffusions.« less

A fully-implicit high-order system thermal-hydraulics model for advanced non-LWR safety analyses

DOE PAGES

Hu, Rui

2016-11-19

An advanced system analysis tool is being developed for advanced reactor safety analysis. This paper describes the underlying physics and numerical models used in the code, including the governing equations, the stabilization schemes, the high-order spatial and temporal discretization schemes, and the Jacobian Free Newton Krylov solution method. The effects of the spatial and temporal discretization schemes are investigated. Additionally, a series of verification test problems are presented to confirm the high-order schemes. Furthermore, it is demonstrated that the developed system thermal-hydraulics model can be strictly verified with the theoretical convergence rates, and that it performs very well for amore » wide range of flow problems with high accuracy, efficiency, and minimal numerical diffusions.« less

Advanced gearbox technology

NASA Technical Reports Server (NTRS)

Anderson, N. E.; Cedoz, R. W.; Salama, E. E.; Wagner, D. A.

1987-01-01

An advanced 13,000 HP, counterrotating (CR) gearbox was designed and successfully tested to provide a technology base for future designs of geared propfan propulsion systems for both commercial and military aircraft. The advanced technology CR gearbox was designed for high efficiency, low weight, long life, and improved maintainability. The differential planetary CR gearbox features double helical gears, double row cylindrical roller bearings integral with planet gears, tapered roller prop support bearings, and a flexible ring gear and diaphragm to provide load sharing. A new Allison propfan back-to-back gearbox test facility was constructed. Extensive rotating and stationary instrumentation was used to measure temperature, strain, vibration, deflection and efficiency under representative flight operating conditions. The tests verified smooth, efficient gearbox operation. The highly-instrumented advanced CR gearbox was successfully tested to design speed and power (13,000 HP), and to a 115 percent overspeed condition. Measured CR gearbox efficiency was 99.3 percent at the design point based on heat loss to the oil. Tests demonstrated low vibration characteristics of double helical gearing, proper gear tooth load sharing, low stress levels, and the high load capacity of the prop tapered roller bearings. Applied external prop loads did not significantly affect gearbox temperature, vibration, or stress levels. Gearbox hardware was in excellent condition after the tests with no indication of distress.

Progress of OLED devices with high efficiency at high luminance

NASA Astrophysics Data System (ADS)

Nguyen, Carmen; Ingram, Grayson; Lu, Zhenghong

2014-03-01

Organic light emitting diodes (OLEDs) have progressed significantly over the last two decades. For years, OLEDs have been promoted as the next generation technology for flat panel displays and solid-state lighting due to their potential for high energy efficiency and dynamic range of colors. Although high efficiency can readily be obtained at low brightness levels, a significant decline at high brightness is commonly observed. In this report, we will review various strategies for achieving highly efficient phosphorescent OLED devices at high luminance. Specifically, we will provide details regarding the performance and general working principles behind each strategy. We will conclude by looking at how some of these strategies can be combined to produce high efficiency white OLEDs at high brightness.

Simulation of the real efficiencies of high-efficiency silicon solar cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sachenko, A. V., E-mail: sach@isp.kiev.ua; Skrebtii, A. I.; Korkishko, R. M.

The temperature dependences of the efficiency η of high-efficiency solar cells based on silicon are calculated. It is shown that the temperature coefficient of decreasing η with increasing temperature decreases as the surface recombination rate decreases. The photoconversion efficiency of high-efficiency silicon-based solar cells operating under natural (field) conditions is simulated. Their operating temperature is determined self-consistently by simultaneously solving the photocurrent, photovoltage, and energy-balance equations. Radiative and convective cooling mechanisms are taken into account. It is shown that the operating temperature of solar cells is higher than the ambient temperature even at very high convection coefficients (~300 W/m{sup 2}more » K). Accordingly, the photoconversion efficiency in this case is lower than when the temperature of the solar cells is equal to the ambient temperature. The calculated dependences for the open-circuit voltage and the photoconversion efficiency of high-quality silicon solar cells under concentrated illumination are discussed taking into account the actual temperature of the solar cells.« less

Coherent optical memory with high storage efficiency and large fractional delay.

PubMed

Chen, Yi-Hsin; Lee, Meng-Jung; Wang, I-Chung; Du, Shengwang; Chen, Yong-Fan; Chen, Ying-Cheng; Yu, Ite A

2013-02-22

A high-storage efficiency and long-lived quantum memory for photons is an essential component in long-distance quantum communication and optical quantum computation. Here, we report a 78% storage efficiency of light pulses in a cold atomic medium based on the effect of electromagnetically induced transparency. At 50% storage efficiency, we obtain a fractional delay of 74, which is the best up-to-date record. The classical fidelity of the recalled pulse is better than 90% and nearly independent of the storage time, as confirmed by the direct measurement of phase evolution of the output light pulse with a beat-note interferometer. Such excellent phase coherence between the stored and recalled light pulses suggests that the current result may be readily applied to single photon wave packets. Our work significantly advances the technology of electromagnetically induced transparency-based optical memory and may find practical applications in long-distance quantum communication and optical quantum computation.

Coherent Optical Memory with High Storage Efficiency and Large Fractional Delay

NASA Astrophysics Data System (ADS)

Chen, Yi-Hsin; Lee, Meng-Jung; Wang, I.-Chung; Du, Shengwang; Chen, Yong-Fan; Chen, Ying-Cheng; Yu, Ite A.

2013-02-01

A high-storage efficiency and long-lived quantum memory for photons is an essential component in long-distance quantum communication and optical quantum computation. Here, we report a 78% storage efficiency of light pulses in a cold atomic medium based on the effect of electromagnetically induced transparency. At 50% storage efficiency, we obtain a fractional delay of 74, which is the best up-to-date record. The classical fidelity of the recalled pulse is better than 90% and nearly independent of the storage time, as confirmed by the direct measurement of phase evolution of the output light pulse with a beat-note interferometer. Such excellent phase coherence between the stored and recalled light pulses suggests that the current result may be readily applied to single photon wave packets. Our work significantly advances the technology of electromagnetically induced transparency-based optical memory and may find practical applications in long-distance quantum communication and optical quantum computation.

High Efficiency InP Solar Cells from Low Toxicity Tertiarybutylphosphine

NASA Technical Reports Server (NTRS)

Hoffman, Richard W., Jr.; Fatemi, Navid S.; Wilt, David M.; Jenkins, Phillip P.; Brinker, David J.; Scheiman, David A.

1994-01-01

Large scale manufacture of phosphide based semiconductor devices by organo-metallic vapor phase epitaxy (OMVPE) typically requires the use of highly toxic phosphine. Advancements in phosphine substitutes have identified tertiarybutylphosphine (TBP) as an excellent precursor for OMVPE of InP. High quality undoped and doped InP films were grown using TBP and trimethylindium. Impurity doped InP films were achieved utilizing diethylzinc and silane for p and n type respectively. 16 percent efficient solar cells under air mass zero, one sun intensity were demonstrated with Voc of 871 mV and fill factor of 82.6 percent. It was shown that TBP could replace phosphine, without adversely affecting device quality, in OMVPE deposition of InP thus significantly reducing toxic gas exposure risk.

High temperature performance of high-efficiency, multi-layer solar selective coatings for tower applications

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gray, M. H.; Tirawat, R.; Kessinger, K. A.

The roadmap to next-generation concentrating solar power plants anticipates a progression to central towers with operating temperatures in excess of 650°C. These higher temperatures are required to drive higher power-cycle efficiencies, resulting in lower cost energy. However, these conditions also place a greater burden on the materials making up the receiver. Any novel absorber material developed for next-generation receivers must be stable in air, cost effective, and survive thousands of heating and cooling cycles. The collection efficiency of a power tower plant can be increased if the energy absorbed by the receiver is maximized while the heat loss from themore » receiver to the environment is minimized. Thermal radiation losses can be significant (>7% annual energy loss) with receivers at temperatures above 650°C. We present progress toward highly efficient and durable solar selective absorbers (SSAs) intended for operating temperatures from 650°C to 1000°C. Selective efficiency (η sel) is defined as the energy retained by the absorber, accounting for both absorptance and emittance, relative to the energy incident on the surface. The low emittance layers of multilayer SSAs are binary compounds of refractory metals whose material properties indicate that coatings formed of these materials should be oxidation resistant in air to 800-1200°C. On this basis, we initially developed a solar selective coating for parabolic troughs. This development has been successfully extended to meet the absorptance and emittance objectives for the more demanding, high temperature regime. We show advancement in coating materials, processing and designs resulting in the initial attainment of target efficiencies η sel > 0.91 for proposed tower conditions. Additionally, spectral measurements show that these coatings continue to perform at targeted levels after cycling to temperatures of 1000°C in environments of nitrogen and forming gas.« less

High temperature performance of high-efficiency, multi-layer solar selective coatings for tower applications

DOE PAGES

Gray, M. H.; Tirawat, R.; Kessinger, K. A.; ...

2015-05-01

The roadmap to next-generation concentrating solar power plants anticipates a progression to central towers with operating temperatures in excess of 650°C. These higher temperatures are required to drive higher power-cycle efficiencies, resulting in lower cost energy. However, these conditions also place a greater burden on the materials making up the receiver. Any novel absorber material developed for next-generation receivers must be stable in air, cost effective, and survive thousands of heating and cooling cycles. The collection efficiency of a power tower plant can be increased if the energy absorbed by the receiver is maximized while the heat loss from themore » receiver to the environment is minimized. Thermal radiation losses can be significant (>7% annual energy loss) with receivers at temperatures above 650°C. We present progress toward highly efficient and durable solar selective absorbers (SSAs) intended for operating temperatures from 650°C to 1000°C. Selective efficiency (η sel) is defined as the energy retained by the absorber, accounting for both absorptance and emittance, relative to the energy incident on the surface. The low emittance layers of multilayer SSAs are binary compounds of refractory metals whose material properties indicate that coatings formed of these materials should be oxidation resistant in air to 800-1200°C. On this basis, we initially developed a solar selective coating for parabolic troughs. This development has been successfully extended to meet the absorptance and emittance objectives for the more demanding, high temperature regime. We show advancement in coating materials, processing and designs resulting in the initial attainment of target efficiencies η sel > 0.91 for proposed tower conditions. Additionally, spectral measurements show that these coatings continue to perform at targeted levels after cycling to temperatures of 1000°C in environments of nitrogen and forming gas.« less

A review of advanced turboprop transport aircraft

NASA Astrophysics Data System (ADS)

Lange, Roy H.

The application of advanced technologies shows the potential for significant improvement in the fuel efficiency and operating costs of future transport aircraft envisioned for operation in the 1990s time period. One of the more promising advanced technologies is embodied in an advanced turboprop concept originated by Hamilton Standard and NASA and known as the propfan. The propfan concept features a highly loaded multibladed, variable pitch propeller geared to a high pressure ratio gas turbine engine. The blades have high sweepback and advanced airfoil sections to achieve 80 percent propulsive efficiency at M=0.80 cruise speed. Aircraft system studies have shown improvements in fuel efficiency of 15-20 percent for propfan advanced transport aircraft as compared to equivalent turbofan transports. Beginning with the Lockheed C-130 and Electra turboprop aircraft, this paper presents an overview of the evolution of propfan aircraft design concepts and system studies. These system studies include possible civil and military transport applications and data on the performance, community and far-field noise characteristics and operating costs of propfan aircraft design concepts. NASA Aircraft Energy Efficiency (ACEE) program propfan projects with industry are reviewed with respect to system studies of propfan aircraft and recommended flight development programs.

High efficiency quantum cascade laser frequency comb.

PubMed

Lu, Quanyong; Wu, Donghai; Slivken, Steven; Razeghi, Manijeh

2017-03-06

An efficient mid-infrared frequency comb source is of great interest to high speed, high resolution spectroscopy and metrology. Here we demonstrate a mid-IR quantum cascade laser frequency comb with a high power output and narrow beatnote linewidth at room temperature. The active region was designed with a strong-coupling between the injector and the upper lasing level for high internal quantum efficiency and a broadband gain. The group velocity dispersion was engineered for efficient, broadband mode-locking via four wave mixing. The comb device exhibits a narrow intermode beatnote linewidth of 50.5 Hz and a maximum wall-plug efficiency of 6.5% covering a spectral coverage of 110 cm -1 at λ ~ 8 μm. The efficiency is improved by a factor of 6 compared with previous demonstrations. The high power efficiency and narrow beatnote linewidth will greatly expand the applications of quantum cascade laser frequency combs including high-precision remote sensing and spectroscopy.

High efficiency quantum cascade laser frequency comb

PubMed Central

Lu, Quanyong; Wu, Donghai; Slivken, Steven; Razeghi, Manijeh

2017-01-01

An efficient mid-infrared frequency comb source is of great interest to high speed, high resolution spectroscopy and metrology. Here we demonstrate a mid-IR quantum cascade laser frequency comb with a high power output and narrow beatnote linewidth at room temperature. The active region was designed with a strong-coupling between the injector and the upper lasing level for high internal quantum efficiency and a broadband gain. The group velocity dispersion was engineered for efficient, broadband mode-locking via four wave mixing. The comb device exhibits a narrow intermode beatnote linewidth of 50.5 Hz and a maximum wall-plug efficiency of 6.5% covering a spectral coverage of 110 cm−1 at λ ~ 8 μm. The efficiency is improved by a factor of 6 compared with previous demonstrations. The high power efficiency and narrow beatnote linewidth will greatly expand the applications of quantum cascade laser frequency combs including high-precision remote sensing and spectroscopy. PMID:28262834

Energy Efficient Engine program advanced turbofan nacelle definition study

NASA Technical Reports Server (NTRS)

Howe, David C.; Wynosky, T. A.

1985-01-01

Advanced, low drag, nacelle configurations were defined for some of the more promising propulsion systems identified in the earlier Benefit/Cost Study, to assess the benefits associated with these advanced technology nacelles and formulate programs for developing these nacelles and low volume thrust reversers/spoilers to a state of technology readiness in the early 1990's. The study results established the design feasibility of advanced technology, slim line nacelles applicable to advanced technology, high bypass ratio turbofan engines. Design feasibility was also established for two low volume thrust reverse/spoiler concepts that meet or exceed the required effectiveness for these engines. These nacelle and thrust reverse/spoiler designs were shown to be applicable in engines with takeoff thrust sizes ranging from 24,000 to 60,000 pounds. The reduced weight, drag, and cost of the advanced technology nacelle installations relative to current technology nacelles offer a mission fuel burn savings ranging from 3.0 to 4.5 percent and direct operating cost plus interest improvements from 1.6 to 2.2 percent.

ADX: A high Power Density, Advanced RF-Driven Divertor Test Tokamak for PMI studies

NASA Astrophysics Data System (ADS)

Whyte, Dennis; ADX Team

2015-11-01

The MIT PSFC and collaborators are proposing an advanced divertor experiment, ADX; a divertor test tokamak dedicated to address critical gaps in plasma-material interactions (PMI) science, and the world fusion research program, on the pathway to FNSF/DEMO. Basic ADX design features are motivated and discussed. In order to assess the widest range of advanced divertor concepts, a large fraction (>50%) of the toroidal field volume is purpose-built with innovative magnetic topology control and flexibility for assessing different surfaces, including liquids. ADX features high B-field (>6 Tesla) and high global power density (P/S ~ 1.5 MW/m2) in order to access the full range of parallel heat flux and divertor plasma pressures foreseen for reactors, while simultaneously assessing the effect of highly dissipative divertors on core plasma/pedestal. Various options for efficiently achieving high field are being assessed including the use of Alcator technology (cryogenic cooled copper) and high-temperature superconductors. The experimental platform would also explore advanced lower hybrid current drive and ion-cyclotron range of frequency actuators located at the high-field side; a location which is predicted to greatly reduce the PMI effects on the launcher while minimally perturbing the core plasma. The synergistic effects of high-field launchers with high total B on current and flow drive can thus be studied in reactor-relevant boundary plasmas.

Highly-efficient quantum memory for polarization qubits in a spatially-multiplexed cold atomic ensemble.

PubMed

Vernaz-Gris, Pierre; Huang, Kun; Cao, Mingtao; Sheremet, Alexandra S; Laurat, Julien

2018-01-25

Quantum memory for flying optical qubits is a key enabler for a wide range of applications in quantum information. A critical figure of merit is the overall storage and retrieval efficiency. So far, despite the recent achievements of efficient memories for light pulses, the storage of qubits has suffered from limited efficiency. Here we report on a quantum memory for polarization qubits that combines an average conditional fidelity above 99% and efficiency around 68%, thereby demonstrating a reversible qubit mapping where more information is retrieved than lost. The qubits are encoded with weak coherent states at the single-photon level and the memory is based on electromagnetically-induced transparency in an elongated laser-cooled ensemble of cesium atoms, spatially multiplexed for dual-rail storage. This implementation preserves high optical depth on both rails, without compromise between multiplexing and storage efficiency. Our work provides an efficient node for future tests of quantum network functionalities and advanced photonic circuits.

Determinants of High Schools' Advanced Course Offerings

ERIC Educational Resources Information Center

Iatarola, Patrice; Conger, Dylan; Long, Mark C.

2011-01-01

This article examines the factors that determine a high school's probability of offering Advanced Placement (AP) and International Baccalaureate (IB) courses. The likelihood that a school offers advanced courses, and the number of sections that it offers, is largely driven by having a critical mass of students who enter high school with…

Multi-petascale highly efficient parallel supercomputer

DOEpatents

Asaad, Sameh; Bellofatto, Ralph E.; Blocksome, Michael A.; Blumrich, Matthias A.; Boyle, Peter; Brunheroto, Jose R.; Chen, Dong; Cher, Chen -Yong; Chiu, George L.; Christ, Norman; Coteus, Paul W.; Davis, Kristan D.; Dozsa, Gabor J.; Eichenberger, Alexandre E.; Eisley, Noel A.; Ellavsky, Matthew R.; Evans, Kahn C.; Fleischer, Bruce M.; Fox, Thomas W.; Gara, Alan; Giampapa, Mark E.; Gooding, Thomas M.; Gschwind, Michael K.; Gunnels, John A.; Hall, Shawn A.; Haring, Rudolf A.; Heidelberger, Philip; Inglett, Todd A.; Knudson, Brant L.; Kopcsay, Gerard V.; Kumar, Sameer; Mamidala, Amith R.; Marcella, James A.; Megerian, Mark G.; Miller, Douglas R.; Miller, Samuel J.; Muff, Adam J.; Mundy, Michael B.; O'Brien, John K.; O'Brien, Kathryn M.; Ohmacht, Martin; Parker, Jeffrey J.; Poole, Ruth J.; Ratterman, Joseph D.; Salapura, Valentina; Satterfield, David L.; Senger, Robert M.; Smith, Brian; Steinmacher-Burow, Burkhard; Stockdell, William M.; Stunkel, Craig B.; Sugavanam, Krishnan; Sugawara, Yutaka; Takken, Todd E.; Trager, Barry M.; Van Oosten, James L.; Wait, Charles D.; Walkup, Robert E.; Watson, Alfred T.; Wisniewski, Robert W.; Wu, Peng

2015-07-14

A Multi-Petascale Highly Efficient Parallel Supercomputer of 100 petaOPS-scale computing, at decreased cost, power and footprint, and that allows for a maximum packaging density of processing nodes from an interconnect point of view. The Supercomputer exploits technological advances in VLSI that enables a computing model where many processors can be integrated into a single Application Specific Integrated Circuit (ASIC). Each ASIC computing node comprises a system-on-chip ASIC utilizing four or more processors integrated into one die, with each having full access to all system resources and enabling adaptive partitioning of the processors to functions such as compute or messaging I/O on an application by application basis, and preferably, enable adaptive partitioning of functions in accordance with various algorithmic phases within an application, or if I/O or other processors are underutilized, then can participate in computation or communication nodes are interconnected by a five dimensional torus network with DMA that optimally maximize the throughput of packet communications between nodes and minimize latency.

3D-Printed, All-in-One Evaporator for High-Efficiency Solar Steam Generation under 1 Sun Illumination.

PubMed

Li, Yiju; Gao, Tingting; Yang, Zhi; Chen, Chaoji; Luo, Wei; Song, Jianwei; Hitz, Emily; Jia, Chao; Zhou, Yubing; Liu, Boyang; Yang, Bao; Hu, Liangbing

2017-07-01

Using solar energy to generate steam is a clean and sustainable approach to addressing the issue of water shortage. The current challenge for solar steam generation is to develop easy-to-manufacture and scalable methods which can convert solar irradiation into exploitable thermal energy with high efficiency. Although various material and structure designs have been reported, high efficiency in solar steam generation usually can be achieved only at concentrated solar illumination. For the first time, 3D printing to construct an all-in-one evaporator with a concave structure for high-efficiency solar steam generation under 1 sun illumination is used. The solar-steam-generation device has a high porosity (97.3%) and efficient broadband solar absorption (>97%). The 3D-printed porous evaporator with intrinsic low thermal conductivity enables heat localization and effectively alleviates thermal dissipation to the bulk water. As a result, the 3D-printed evaporator has a high solar steam efficiency of 85.6% under 1 sun illumination (1 kW m -2 ), which is among the best compared with other reported evaporators. The all-in-one structure design using the advanced 3D printing fabrication technique offers a new approach to solar energy harvesting for high-efficiency steam generation. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

[Characteristics of phosphorus uptake and use efficiency of rice with high yield and high phosphorus use efficiency].

PubMed

Li, Li; Zhang, Xi-Zhou; Li, Tinx-Xuan; Yu, Hai-Ying; Ji, Lin; Chen, Guang-Deng

2014-07-01

A total of twenty seven middle maturing rice varieties as parent materials were divided into four types based on P use efficiency for grain yield in 2011 by field experiment with normal phosphorus (P) application. The rice variety with high yield and high P efficiency was identified by pot experiment with normal and low P applications, and the contribution rates of various P efficiencies to yield were investigated in 2012. There were significant genotype differences in yield and P efficiency of the test materials. GRLu17/AiTTP//Lu17_2 (QR20) was identified as a variety with high yield and high P efficiency, and its yields at the low and normal rates of P application were 1.96 and 1.92 times of that of Yuxiang B, respectively. The contribution rate of P accumulation to yield was greater than that of P grain production efficiency and P harvest index across field and pot experiments. The contribution rates of P accumulation and P grain production efficiency to yield were not significantly different under the normal P condition, whereas obvious differences were observed under the low P condition (66.5% and 26.6%). The minimal contribution to yield was P harvest index (11.8%). Under the normal P condition, the contribution rates of P accumulation to yield and P harvest index were the highest at the jointing-heading stage, which were 93.4% and 85.7%, respectively. In addition, the contribution rate of P accumulation to grain production efficiency was 41.8%. Under the low P condition, the maximal contribution rates of P accumulation to yield and grain production efficiency were observed at the tillering-jointing stage, which were 56.9% and 20.1% respectively. Furthermore, the contribution rate of P accumulation to P harvest index was 16.0%. The yield, P accumulation, and P harvest index of QR20 significantly increased under the normal P condition by 20.6%, 18.1% and 18.2% respectively compared with that in the low P condition. The rank of the contribution rates of P

Graphene-based Recyclable Photo-Absorbers for High-Efficiency Seawater Desalination.

PubMed

Wang, Xiangqing; Ou, Gang; Wang, Ning; Wu, Hui

2016-04-13

Today's scientific advances in water desalination dramatically increase our ability to transform seawater into fresh water. As an important source of renewable energy, solar power holds great potential to drive the desalination of seawater. Previously, solar assisted evaporation systems usually relied on highly concentrated sunlight or were not suitable to treat seawater or wastewater, severely limiting the large scale application of solar evaporation technology. Thus, a new strategy is urgently required in order to overcome these problems. In this study, we developed a solar thermal evaporation system based on reduced graphene oxide (rGO) decorated with magnetic nanoparticles (MNPs). Because this material can absorb over 95% of sunlight, we achieved high evaporation efficiency up to 70% under only 1 kW m(-2) irradiation. Moreover, it could be separated from seawater under the action of magnetic force by decorated with MNPs. Thus, this system provides an advantage of recyclability, which can significantly reduce the material consumptions. Additionally, by using photoabsorbing bulk or layer materials, the deposition of solutes offen occurs in pores of materials during seawater desalination, leading to the decrease of efficiency. However, this problem can be easily solved by using MNPs, which suggests this system can be used in not only pure water system but also high-salinity wastewater system. This study shows good prospects of graphene-based materials for seawater desalination and high-salinity wastewater treatment.

Building America Case Study: Simple Retrofit High-Efficiency Natural Gas Water Heater Field Test, Minneapolis, Minnesota

DOE Office of Scientific and Technical Information (OSTI.GOV)

High performance water heaters are typically more time consuming and costly to install in retrofit applications, making high performance water heaters difficult to justify economically. However, recent advancements in high performance water heaters have targeted the retrofit market, simplifying installations and reducing costs. Four high efficiency natural gas water heaters designed specifically for retrofit applications were installed in single-family homes along with detailed monitoring systems to characterize their savings potential, their installed efficiencies, and their ability to meet household demands. The water heaters tested for this project were designed to improve the cost-effectiveness and increase market penetration of high efficiencymore » water heaters in the residential retrofit market. The retrofit high efficiency water heaters achieved their goal of reducing costs, maintaining savings potential and installed efficiency of other high efficiency water heaters, and meeting the necessary capacity in order to improve cost-effectiveness. However, the improvements were not sufficient to achieve simple paybacks of less than ten years for the incremental cost compared to a minimum efficiency heater. Significant changes would be necessary to reduce the simple payback to six years or less. Annual energy savings in the range of $200 would also reduce paybacks to less than six years. These energy savings would require either significantly higher fuel costs (greater than $1.50 per therm) or very high usage (around 120 gallons per day). For current incremental costs, the water heater efficiency would need to be similar to that of a heat pump water heater to deliver a six year payback.« less

Highly Efficient Quantum Sieving in Porous Graphene-like Carbon Nitride for Light Isotopes Separation

NASA Astrophysics Data System (ADS)

Qu, Yuanyuan; Li, Feng; Zhou, Hongcai; Zhao, Mingwen

2016-01-01

Light isotopes separation, such as 3He/4He, H2/D2, H2/T2, etc., is crucial for various advanced technologies including isotope labeling, nuclear weapons, cryogenics and power generation. However, their nearly identical chemical properties made the separation challenging. The low productivity of the present isotopes separation approaches hinders the relevant applications. An efficient membrane with high performance for isotopes separation is quite appealing. Based on first-principles calculations, we theoretically demonstrated that highly efficient light isotopes separation, such as 3He/4He, can be reached in a porous graphene-like carbon nitride material via quantum sieving effect. Under moderate tensile strain, the quantum sieving of the carbon nitride membrane can be effectively tuned in a continuous way, leading to a temperature window with high 3He/4He selectivity and permeance acceptable for efficient isotopes harvest in industrial application. This mechanism also holds for separation of other light isotopes, such as H2/D2, H2/T2. Such tunable quantum sieving opens a promising avenue for light isotopes separation for industrial application.

High-Purity Aluminum Magnet Technology for Advanced Space Transportation Systems

NASA Technical Reports Server (NTRS)

Goodrich, R. G.; Pullam, B.; Rickle, D.; Litchford, R. J.; Robertson, G. A.; Schmidt, D. D.; Cole, John (Technical Monitor)

2001-01-01

Basic research on advanced plasma-based propulsion systems is routinely focused on plasmadynamics, performance, and efficiency aspects while relegating the development of critical enabling technologies, such as flight-weight magnets, to follow-on development work. Unfortunately, the low technology readiness levels (TRLs) associated with critical enabling technologies tend to be perceived as an indicator of high technical risk, and this, in turn, hampers the acceptance of advanced system architectures for flight development. Consequently, there is growing recognition that applied research on the critical enabling technologies needs to be conducted hand in hand with basic research activities. The development of flight-weight magnet technology, for example, is one area of applied research having broad crosscutting applications to a number of advanced propulsion system architectures. Therefore, NASA Marshall Space Flight Center, Louisiana State University (LSU), and the National High Magnetic Field Laboratory (NHMFL) have initiated an applied research project aimed at advancing the TRL of flight-weight magnets. This Technical Publication reports on the group's initial effort to demonstrate the feasibility of cryogenic high-purity aluminum magnet technology and describes the design, construction, and testing of a 6-in-diameter by 12-in-long aluminum solenoid magnet. The coil was constructed in the machine shop of the Department of Physics and Astronomy at LSU and testing was conducted in NHMFL facilities at Florida State University and at Los Alamos National Laboratory. The solenoid magnet was first wound, reinforced, potted in high thermal conductivity epoxy, and bench tested in the LSU laboratories. A cryogenic container for operation at 77 K was also constructed and mated to the solenoid. The coil was then taken to NHMFL facilities in Tallahassee, FL. where its magnetoresistance was measured in a 77 K environment under steady magnetic fields as high as 10 T. In

High-efficiency, broad band, high-damage threshold high-index gratings for femtosecond pulse compression.

PubMed

Canova, Frederico; Clady, Raphael; Chambaret, Jean-Paul; Flury, Manuel; Tonchev, Svtelen; Fechner, Renate; Parriaux, Olivier

2007-11-12

High efficiency, broad-band TE-polarization diffraction over a wavelength range centered at 800 nm is obtained by high index gratings placed on a non-corrugated mirror. More than 96% efficiency wide band top-hat diffraction efficiency spectra, as well as more than 1 J/cm(2) damage threshold under 50 fs pulses are demonstrated experimentally. This opens the way to high-efficiency Chirped Pulse Amplification for high average power laser machining by means of all-dielectric structures as well as for ultra-short high energy pulses by means of metal-dielectric structures.

High temperature, harsh environment sensors for advanced power generation systems

NASA Astrophysics Data System (ADS)

Ohodnicki, P. R.; Credle, S.; Buric, M.; Lewis, R.; Seachman, S.

2015-05-01

One mission of the Crosscutting Technology Research program at the National Energy Technology Laboratory is to develop a suite of sensors and controls technologies that will ultimately increase efficiencies of existing fossil-fuel fired power plants and enable a new generation of more efficient and lower emission power generation technologies. The program seeks to accomplish this mission through soliciting, managing, and monitoring a broad range of projects both internal and external to the laboratory which span sensor material and device development, energy harvesting and wireless telemetry methodologies, and advanced controls algorithms and approaches. A particular emphasis is placed upon harsh environment sensing for compatibility with high temperature, erosive, corrosive, and highly reducing or oxidizing environments associated with large-scale centralized power generation. An overview of the full sensors and controls portfolio is presented and a selected set of current and recent research successes and on-going projects are highlighted. A more detailed emphasis will be placed on an overview of the current research thrusts and successes of the in-house sensor material and device research efforts that have been established to support the program.

Energy efficient engine high pressure turbine test hardware detailed design report

NASA Technical Reports Server (NTRS)

Halila, E. E.; Lenahan, D. T.; Thomas, T. T.

1982-01-01

The high pressure turbine configuration for the Energy Efficient Engine is built around a two-stage design system. Moderate aerodynamic loading for both stages is used to achieve the high level of turbine efficiency. Flowpath components are designed for 18,000 hours of life, while the static and rotating structures are designed for 36,000 hours of engine operation. Both stages of turbine blades and vanes are air-cooled incorporating advanced state of the art in cooling technology. Direct solidification (DS) alloys are used for blades and one stage of vanes, and an oxide dispersion system (ODS) alloy is used for the Stage 1 nozzle airfoils. Ceramic shrouds are used as the material composition for the Stage 1 shroud. An active clearance control (ACC) system is used to control the blade tip to shroud clearances for both stages. Fan air is used to impinge on the shroud casing support rings, thereby controlling the growth rate of the shroud. This procedure allows close clearance control while minimizing blade tip to shroud rubs.

High efficiency, long life terrestrial solar panel

NASA Technical Reports Server (NTRS)

Chao, T.; Khemthong, S.; Ling, R.; Olah, S.

1977-01-01

The design of a high efficiency, long life terrestrial module was completed. It utilized 256 rectangular, high efficiency solar cells to achieve high packing density and electrical output. Tooling for the fabrication of solar cells was in house and evaluation of the cell performance was begun. Based on the power output analysis, the goal of a 13% efficiency module was achievable.

Characteristics of High- and Low-Efficiency Hospitals.

PubMed

Rosko, Michael; Wong, Herbert S; Mutter, Ryan

2017-01-01

We compared performance, operating characteristics, and market environments of low- and high-efficiency hospitals in the 37 states that supplied inpatient data to the Healthcare Cost and Utilization Project from 2006 to 2010. Hospital cost-inefficiency estimates using stochastic frontier analysis were generated. Hospitals were then grouped into the 100 most- and 100 least-efficient hospitals for subsequent analysis. Compared with the least efficient hospitals, high-efficiency hospitals tended to have lower average costs, higher labor productivity, and higher profit margins. The most efficient hospitals tended to be nonteaching, investor-owned, and members of multihospital systems. Hospitals in the high-efficiency group were located in areas with lower health maintenance organization penetration and less competition, and they had a higher share of Medicaid and Medicare admissions. Results of the analysis suggest there are opportunities for public policies to support improved efficiency in the hospital sector.

High-Performance Three-Stage Cascade Thermoelectric Devices with 20% Efficiency

NASA Astrophysics Data System (ADS)

Cook, B. A.; Chan, T. E.; Dezsi, G.; Thomas, P.; Koch, C. C.; Poon, J.; Tritt, T.; Venkatasubramanian, R.

2015-06-01

The use of advanced materials has resulted in a significant improvement in thermoelectric device conversion efficiency. Three-stage cascade devices were assembled, consisting of nano-bulk Bi2Te3-based materials on the cold side, PbTe and enhanced TAGS-85 [(AgSbTe2)15(GeTe)85] for the mid-stage, and half-Heusler alloys for the high-temperature top stage. In addition, an area aspect ratio optimization process was applied in order to account for asymmetric thermal transport down the individual n- and p-legs. The n- and p-type chalcogenide alloy materials were prepared by high-energy mechanical ball-milling and/or cryogenic ball-milling of elementary powders, with subsequent consolidation by high-pressure uniaxial hot-pressing. The low-temperature stage materials, nano-bulk Bi2Te3- x Sb x and Bi2Te3- x Se x , exhibit a unique mixture of nanoscale features that leads to an enhanced Seebeck coefficient and reduced lattice thermal conductivity, thereby achieving an average ZT of ~1.26 and ~1.7 in the 27°C to 100°C range for the n-type and p-type materials, respectively. Also, the addition of small amounts of selected rare earth elements has been shown to improve the ZT of TAGS-85 by 25%, compared with conventional or neat TAGS-85, resulting in a ZT = 1.5 at 400°C. The incorporation of these improved materials resulted in a peak device conversion efficiency of ~20% at a temperature difference of 750°C when corrected for radiation heat losses and thermal conduction losses through the lead wires. These high-efficiency results were shown to be reproducible across multiple cascade devices.

Advanced Multilayer Composite Heavy-Oxide Scintillator Detectors for High Efficiency Fast Neutron Detection

NASA Astrophysics Data System (ADS)

Ryzhikov, Vladimir D.; Naydenov, Sergei V.; Pochet, Thierry; Onyshchenko, Gennadiy M.; Piven, Leonid A.; Smith, Craig F.

2018-01-01

We have developed and evaluated a new approach to fast neutron and neutron-gamma detection based on large-area multilayer composite heterogeneous detection media consisting of dispersed granules of small-crystalline scintillators contained in a transparent organic (plastic) matrix. Layers of the composite material are alternated with layers of transparent plastic scintillator material serving as light guides. The resulting detection medium - designated as ZEBRA - serves as both an active neutron converter and a detection scintillator which is designed to detect both neutrons and gamma-quanta. The composite layers of the ZEBRA detector consist of small heavy-oxide scintillators in the form of granules of crystalline BGO, GSO, ZWO, PWO and other materials. We have produced and tested the ZEBRA detector of sizes 100x100x41 mm and greater, and determined that they have very high efficiency of fast neutron detection (up to 49% or greater), comparable to that which can be achieved by large sized heavy-oxide single crystals of about Ø40x80 cm3 volume. We have also studied the sensitivity variation to fast neutron detection by using different types of multilayer ZEBRA detectors of 100 cm2 surface area and 41 mm thickness (with a detector weight of about 1 kg) and found it to be comparable to the sensitivity of a 3He-detector representing a total cross-section of about 2000 cm2 (with a weight of detector, including its plastic moderator, of about 120 kg). The measured count rate in response to a fast neutron source of 252Cf at 2 m for the ZEBRA-GSO detector of size 100x100x41 mm3 was 2.84 cps/ng, and this count rate can be doubled by increasing the detector height (and area) up to 200x100 mm2. In summary, the ZEBRA detectors represent a new type of high efficiency and low cost solid-state neutron detector that can be used for stationary neutron/gamma portals. They may represent an interesting alternative to expensive, bulky gas counters based on 3He or 10B neutron

High efficiency laser-pumped emerald lasers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lai, S.T.

1987-09-25

Highly efficient laser operation has been achieved in emerald. In a quasi-cw laser-pumped emerald laser, 64% output slope efficiency has been measured at 768 nm, corresponding to a laser quantum yield of 76%. An output power of 1.6 W was reached at 3.6 W of pump power at 647.1 nm from a krypton laser, and was pump power limited. The emerald laser has a tuning range of 720 to 842 nm. The round trip loss excluding the excited state absorption (ESA) is 0.4%/cm. These results indicate the high laser efficiency and the high optical quality of the emerald attainable inmore » the present laser.« less

High-efficiency cavity-dumped micro-chip Yb:YAG laser

NASA Astrophysics Data System (ADS)

Nishio, M.; Maruko, A.; Inoue, M.; Takama, M.; Matsubara, S.; Okunishi, H.; Kato, K.; Kyomoto, K.; Yoshida, T.; Shimabayashi, K.; Morioka, M.; Inayoshi, S.; Yamagata, S.; Kawato, S.

2014-09-01

High-efficiency cavity-dumped ytterbium-doped yttrium aluminum garnet (Yb:YAG) laser was developed. Although the high quantum efficiency of ytterbium-doped laser materials is appropriate for high-efficiency laser oscillation, the efficiency is decreased by their quasi-three/four laser natures. High gain operation by high intensity pumping is suitable for high efficiency oscillation on the quasi-three/four lasers without extremely low temperature cooling. In our group, highest efficiency oscillations for continuous wave, nanosecond to picosecond pulse lasers were achieved at room temperature by the high gain operation in which pump intensities were beyond 100 kW/cm2.

High efficiency SPS klystron design

NASA Technical Reports Server (NTRS)

Nalos, E. J.

1980-01-01

The most likely compact configuration to realize both high efficiency and high gain (approx. 40 dB) is a 5-6 cavity design focused by an electromagnet. The basic klystron efficiency cannot be expected to exceed 70-75% without collector depression. It was estimated that the net benefit of a 5 stage collector over a 2 stage collector is between 1.5 and 3.5 kW per tube. A modulating anode is incorporated in the design to enable rapid shutoff of the beam current in case the r.f. drive should be removed.

Highly Efficient TADF Polymer Electroluminescence with Reduced Efficiency Roll-off via Interfacial Exciplex Host Strategy.

PubMed

Lin, Xingdong; Zhu, Yunhui; Zhang, Baohua; Zhao, Xiaofei; Yao, Bing; Cheng, Yanxiang; Li, Zhanguo; Qu, Yi; Xie, Zhiyuan

2018-01-10

Solution-processed organic light-emitting diodes (s-OLED) consisting of TAPC/TmPyPB interfacial exciplex host and polymer PAPTC TADF emitter are prepared, simultaneously displaying ultralow voltages (2.50/2.91/3.51/4.91 V at luminance of 1/100/1000/1000 cd m -2 ), high efficiencies (14.9%, 50.1 lm W -1 ), and extremely low roll-off rates (J 50 of 63.16 mA cm -2 , L 50 of ca. 15000 cd m -2 ). Such performance is distinctly higher than that of pure-PAPTC s-OLED. Compared to pure-PAPTC, the advanced emissive layer structure of TAPC:PAPTC/TmPyPB is unique in much higher PL quantum yield (79.5 vs 36.3%) and nearly 4-fold enhancement in k RISC of the PAPTC emitter to 1.48 × 10 7 s -1 .

Experimental Investigation and Fundamental Understanding of a Slowed UH-60A Rotor at High Advance Ratios

NASA Technical Reports Server (NTRS)

Datta, Anubhav; Yeo, Hyeonsoo; Norman, Thomas R.

2011-01-01

This paper describes and analyzes the measurements from a full-scale, slowed RPM, UH-60A rotor tested at the National Full-Scale Aerodynamics Complex 40- by 80- ft wind tunnel up to an advance ratio of 1.0. A comprehensive set of measurements, that includes performance, blade loads, hub loads and pressures/airloads makes this data set unique. The measurements reveal new and rich aeromechanical phenomena that are special to this exotic regime. These include reverse chord dynamic stall, retreating side impulse in pitch-link load, large inboard-outboard elastic twist differential, supersonic flow at low subsonic advancing tip Mach numbers, diminishing rotor forces yet dramatic build up of blade loads, and dramatic blade loads yet benign levels of vibratory hub loads. The objective of this research is the fundamental understanding of these unique aeromechanical phenomena. The intent is to provide useful knowledge for the design of high speed, high efficiency, slowed RPM rotors of the future and a challenging database for advanced analyses validation.

Self-assembly of highly efficient, broadband plasmonic absorbers for solar steam generation

PubMed Central

Zhou, Lin; Tan, Yingling; Ji, Dengxin; Zhu, Bin; Zhang, Pei; Xu, Jun; Gan, Qiaoqiang; Yu, Zongfu; Zhu, Jia

2016-01-01

The study of ideal absorbers, which can efficiently absorb light over a broad range of wavelengths, is of fundamental importance, as well as critical for many applications from solar steam generation and thermophotovoltaics to light/thermal detectors. As a result of recent advances in plasmonics, plasmonic absorbers have attracted a lot of attention. However, the performance and scalability of these absorbers, predominantly fabricated by the top-down approach, need to be further improved to enable widespread applications. We report a plasmonic absorber which can enable an average measured absorbance of ~99% across the wavelengths from 400 nm to 10 μm, the most efficient and broadband plasmonic absorber reported to date. The absorber is fabricated through self-assembly of metallic nanoparticles onto a nanoporous template by a one-step deposition process. Because of its efficient light absorption, strong field enhancement, and porous structures, which together enable not only efficient solar absorption but also significant local heating and continuous stream flow, plasmonic absorber–based solar steam generation has over 90% efficiency under solar irradiation of only 4-sun intensity (4 kW m−2). The pronounced light absorption effect coupled with the high-throughput self-assembly process could lead toward large-scale manufacturing of other nanophotonic structures and devices. PMID:27152335

Self-assembly of highly efficient, broadband plasmonic absorbers for solar steam generation.

PubMed

Zhou, Lin; Tan, Yingling; Ji, Dengxin; Zhu, Bin; Zhang, Pei; Xu, Jun; Gan, Qiaoqiang; Yu, Zongfu; Zhu, Jia

2016-04-01

The study of ideal absorbers, which can efficiently absorb light over a broad range of wavelengths, is of fundamental importance, as well as critical for many applications from solar steam generation and thermophotovoltaics to light/thermal detectors. As a result of recent advances in plasmonics, plasmonic absorbers have attracted a lot of attention. However, the performance and scalability of these absorbers, predominantly fabricated by the top-down approach, need to be further improved to enable widespread applications. We report a plasmonic absorber which can enable an average measured absorbance of ~99% across the wavelengths from 400 nm to 10 μm, the most efficient and broadband plasmonic absorber reported to date. The absorber is fabricated through self-assembly of metallic nanoparticles onto a nanoporous template by a one-step deposition process. Because of its efficient light absorption, strong field enhancement, and porous structures, which together enable not only efficient solar absorption but also significant local heating and continuous stream flow, plasmonic absorber-based solar steam generation has over 90% efficiency under solar irradiation of only 4-sun intensity (4 kW m(-2)). The pronounced light absorption effect coupled with the high-throughput self-assembly process could lead toward large-scale manufacturing of other nanophotonic structures and devices.

High-efficiency solid state power amplifier

NASA Technical Reports Server (NTRS)

Wallis, Robert E. (Inventor); Cheng, Sheng (Inventor)

2005-01-01

A high-efficiency solid state power amplifier (SSPA) for specific use in a spacecraft is provided. The SSPA has a mass of less than 850 g and includes two different X-band power amplifier sections, i.e., a lumped power amplifier with a single 11-W output and a distributed power amplifier with eight 2.75-W outputs. These two amplifier sections provide output power that is scalable from 11 to 15 watts without major design changes. Five different hybrid microcircuits, including high-efficiency Heterostructure Field Effect Transistor (HFET) amplifiers and Monolithic Microwave Integrated Circuit (MMIC) phase shifters have been developed for use within the SSPA. A highly efficient packaging approach enables the integration of a large number of hybrid circuits into the SSPA.

Ultra-high-speed variable focus optics for novel applications in advanced imaging

NASA Astrophysics Data System (ADS)

Kang, S.; Dotsenko, E.; Amrhein, D.; Theriault, C.; Arnold, C. B.

2018-02-01

With the advancement of ultra-fast manufacturing technologies, high speed imaging with high 3D resolution has become increasingly important. Here we show the use of an ultra-high-speed variable focus optical element, the TAG Lens, to enable new ways to acquire 3D information from an object. The TAG Lens uses sound to adjust the index of refraction profile in a liquid and thereby can achieve focal scanning rates greater than 100 kHz. When combined with a high-speed pulsed LED and a high-speed camera, we can exploit this phenomenon to achieve high-resolution imaging through large depths. By combining the image acquisition with digital image processing, we can extract relevant parameters such as tilt and angle information from objects in the image. Due to the high speeds at which images can be collected and processed, we believe this technique can be used as an efficient method of industrial inspection and metrology for high throughput applications.

Towards energy efficient operation of Heating, Ventilation and Air Conditioning systems via advanced supervisory control design

NASA Astrophysics Data System (ADS)

Oswiecinska, A.; Hibbs, J.; Zajic, I.; Burnham, K. J.

2015-11-01

This paper presents conceptual control solution for reliable and energy efficient operation of heating, ventilation and air conditioning (HVAC) systems used in large volume building applications, e.g. warehouse facilities or exhibition centres. Advanced two-level scalable control solution, designed to extend capabilities of the existing low-level control strategies via remote internet connection, is presented. The high-level, supervisory controller is based on Model Predictive Control (MPC) architecture, which is the state-of-the-art for indoor climate control systems. The innovative approach benefits from using passive heating and cooling control strategies for reducing the HVAC system operational costs, while ensuring that required environmental conditions are met.

Advanced scoring method of eco-efficiency in European cities.

PubMed

Moutinho, Victor; Madaleno, Mara; Robaina, Margarita; Villar, José

2018-01-01

This paper analyzes a set of selected German and French cities' performance in terms of the relative behavior of their eco-efficiencies, computed as the ratio of their gross domestic product (GDP) over their CO 2 emissions. For this analysis, eco-efficiency scores of the selected cities are computed using the data envelopment analysis (DEA) technique, taking the eco-efficiencies as outputs, and the inputs being the energy consumption, the population density, the labor productivity, the resource productivity, and the patents per inhabitant. Once DEA results are analyzed, the Malmquist productivity indexes (MPI) are used to assess the time evolution of the technical efficiency, technological efficiency, and productivity of the cities over the window periods 2000 to 2005 and 2005 to 2008. Some of the main conclusions are that (1) most of the analyzed cities seem to have suboptimal scales, being one of the causes of their inefficiency; (2) there is evidence that high GDP over CO 2 emissions does not imply high eco-efficiency scores, meaning that DEA like approaches are useful to complement more simplistic ranking procedures, pointing out potential inefficiencies at the input levels; (3) efficiencies performed worse during the period 2000-2005 than during the period 2005-2008, suggesting the possibility of corrective actions taken during or at the end of the first period but impacting only on the second period, probably due to an increasing environmental awareness of policymakers and governors; and (4) MPI analysis shows a positive technological evolution of all cities, according to the general technological evolution of the reference cities, reflecting a generalized convergence of most cities to their technological frontier and therefore an evolution in the right direction.

Secondary Heat Exchanger Design and Comparison for Advanced High Temperature Reactor

DOE Office of Scientific and Technical Information (OSTI.GOV)

Piyush Sabharwall; Ali Siahpush; Michael McKellar

2012-06-01

The goals of next generation nuclear reactors, such as the high temperature gas-cooled reactor and advance high temperature reactor (AHTR), are to increase energy efficiency in the production of electricity and provide high temperature heat for industrial processes. The efficient transfer of energy for industrial applications depends on the ability to incorporate effective heat exchangers between the nuclear heat transport system and the industrial process heat transport system. The need for efficiency, compactness, and safety challenge the boundaries of existing heat exchanger technology, giving rise to the following study. Various studies have been performed in attempts to update the secondarymore » heat exchanger that is downstream of the primary heat exchanger, mostly because its performance is strongly tied to the ability to employ more efficient conversion cycles, such as the Rankine super critical and subcritical cycles. This study considers two different types of heat exchangers—helical coiled heat exchanger and printed circuit heat exchanger—as possible options for the AHTR secondary heat exchangers with the following three different options: (1) A single heat exchanger transfers all the heat (3,400 MW(t)) from the intermediate heat transfer loop to the power conversion system or process plants; (2) Two heat exchangers share heat to transfer total heat of 3,400 MW(t) from the intermediate heat transfer loop to the power conversion system or process plants, each exchanger transfers 1,700 MW(t) with a parallel configuration; and (3) Three heat exchangers share heat to transfer total heat of 3,400 MW(t) from the intermediate heat transfer loop to the power conversion system or process plants. Each heat exchanger transfers 1,130 MW(t) with a parallel configuration. A preliminary cost comparison will be provided for all different cases along with challenges and recommendations.« less

High efficiency incandescent lighting

DOEpatents

Bermel, Peter; Ilic, Ognjen; Chan, Walker R.; Musabeyoglu, Ahmet; Cukierman, Aviv Ruben; Harradon, Michael Robert; Celanovic, Ivan; Soljacic, Marin

2014-09-02

Incandescent lighting structure. The structure includes a thermal emitter that can, but does not have to, include a first photonic crystal on its surface to tailor thermal emission coupled to, in a high-view-factor geometry, a second photonic filter selected to reflect infrared radiation back to the emitter while passing visible light. This structure is highly efficient as compared to standard incandescent light bulbs.

Correlated selection response of fiber properties measured by high volume instrument and advanced fiber information system in Upland cotton

USDA-ARS?s Scientific Manuscript database

Fiber properties measured by high volume instrument (HVI) and advanced fiber information system (AFIS) are currently being used in Upland cotton (Gossypium hirsutum L.) breeding. It would be interesting to know if selections for parameters measured by the two instrumental systems are equally effici...

Advances in indirect detector systems for ultra high-speed hard X-ray imaging with synchrotron light

NASA Astrophysics Data System (ADS)

Olbinado, M. P.; Grenzer, J.; Pradel, P.; De Resseguier, T.; Vagovic, P.; Zdora, M.-C.; Guzenko, V. A.; David, C.; Rack, A.

2018-04-01

We report on indirect X-ray detector systems for various full-field, ultra high-speed X-ray imaging methodologies, such as X-ray phase-contrast radiography, diffraction topography, grating interferometry and speckle-based imaging performed at the hard X-ray imaging beamline ID19 of the European Synchrotron—ESRF. Our work highlights the versatility of indirect X-ray detectors to multiple goals such as single synchrotron pulse isolation, multiple-frame recording up to millions frames per second, high efficiency, and high spatial resolution. Besides the technical advancements, potential applications are briefly introduced and discussed.

High Power and Efficiency Space Traveling-Wave Tube Amplifiers With Reduced Size and Mass for NASA Missions

NASA Technical Reports Server (NTRS)

Simons, Rainee N.; Wilson, Jeffrey D.; Force, Dale A.

2008-01-01

Recent advances in high power and efficiency space traveling-wave tube amplifiers (TWTAs) for NASA s space-to-Earth communications are presented in this paper. The RF power and efficiency of a new K-Band amplifier are 40 W and 50 percent and that of a new Ka-Band amplifier are 200 W and 60 percent. An important figure-of-merit, which is defined as the ratio of the RF power output to the mass (W/kg) of a TWT has improved by a factor of ten over the previous generation Ka-Band devices.

High energy efficient solid state laser sources

NASA Technical Reports Server (NTRS)

Byer, Robert L.

1989-01-01

Recent progress in the development of highly efficient coherent optical sources was reviewed. This work has focused on nonlinear frequency conversion of the highly coherent output of the non-planar ring laser oscillators developed earlier in the program, and includes high efficiency second harmonic generation and the operation of optical parametric oscillators for wavelength diversity and tunability.

High energy efficient solid state laser sources

NASA Technical Reports Server (NTRS)

Byer, Robert L.

1988-01-01

Recent progress in the development of highly efficient coherent optical sources is reviewed. This work focusses on nonlinear frequency conversion of the highly coherent output of the Non-Planar Ring Laser Oscillators developed earlier in the program, and includes high efficiency second harmonic generation and the operation of optical parametric oscillators for wavelength diversity and tunability.

Highly Efficient Nondoped Green Organic Light-Emitting Diodes with Combination of High Photoluminescence and High Exciton Utilization.

PubMed

Wang, Chu; Li, Xianglong; Pan, Yuyu; Zhang, Shitong; Yao, Liang; Bai, Qing; Li, Weijun; Lu, Ping; Yang, Bing; Su, Shijian; Ma, Yuguang

2016-02-10

Photoluminescence (PL) efficiency and exciton utilization efficiency are two key parameters to harvest high-efficiency electroluminescence (EL) in organic light-emitting diodes (OLEDs). But it is not easy to simultaneously combine these two characteristics (high PL efficiency and high exciton utilization) into a fluorescent material. In this work, an efficient combination was achieved through two concepts of hybridized local and charge-transfer (CT) state (HLCT) and "hot exciton", in which the former is responsible for high PL efficiency while the latter contributes to high exciton utilization. On the basis of a tiny chemical modification in TPA-BZP, a green-light donor-acceptor molecule, we designed and synthesized CzP-BZP with this efficeient combination of high PL efficiency of η(PL) = 75% in the solid state and maximal exciton utilization efficiency up to 48% (especially, the internal quantum efficiency of η(IQE) = 35% substantially exceed 25% of spin statistics limit) in OLED. The nondoped OLED of CzP-BZP exhibited an excellent performance: a green emission with a CIE coordinate of (0.34, 0.60), a maximum current efficiency of 23.99 cd A(-1), and a maximum external quantum efficiency (EQE, η(EQE)) of 6.95%. This combined HLCT state and "hot exciton" strategy should be a practical way to design next-generation, low-cost, high-efficiency fluorescent OLED materials.

Enabling High Efficiency Ethanol Engines

DOE Office of Scientific and Technical Information (OSTI.GOV)

Szybist, J.; Confer, K.

2011-03-01

Delphi Automotive Systems and ORNL established this CRADA to explore the potential to improve the energy efficiency of spark-ignited engines operating on ethanol-gasoline blends. By taking advantage of the fuel properties of ethanol, such as high compression ratio and high latent heat of vaporization, it is possible to increase efficiency with ethanol blends. Increasing the efficiency with ethanol-containing blends aims to remove a market barrier of reduced fuel economy with E85 fuel blends, which is currently about 30% lower than with petroleum-derived gasoline. The same or higher engine efficiency is achieved with E85, and the reduction in fuel economy ismore » due to the lower energy density of E85. By making ethanol-blends more efficient, the fuel economy gap between gasoline and E85 can be reduced. In the partnership between Delphi and ORNL, each organization brought a unique and complementary set of skills to the project. Delphi has extensive knowledge and experience in powertrain components and subsystems as well as overcoming real-world implementation barriers. ORNL has extensive knowledge and expertise in non-traditional fuels and improving engine system efficiency for the next generation of internal combustion engines. Partnering to combine these knowledge bases was essential towards making progress to reducing the fuel economy gap between gasoline and E85. ORNL and Delphi maintained strong collaboration throughout the project. Meetings were held regularly, usually on a bi-weekly basis, with additional reports, presentations, and meetings as necessary to maintain progress. Delphi provided substantial hardware support to the project by providing components for the single-cylinder engine experiments, engineering support for hardware modifications, guidance for operational strategies on engine research, and hardware support by providing a flexible multi-cylinder engine to be used for optimizing engine efficiency with ethanol-containing fuels.« less

High efficiency thermal to electric energy conversion using selective emitters and spectrally tuned solar cells

NASA Technical Reports Server (NTRS)

Chubb, Donald L.; Flood, Dennis J.; Lowe, Roland A.

1992-01-01

Thermophotovoltaic (TPV) systems are attractive possibilities for direct thermal-to-electric energy conversion, but have typically required the use of black body radiators operating at high temperatures. Recent advances in both the understanding and performance of solid rare-earth oxide selective emitters make possible the use of TPV at temperatures as low as 1500 K. Depending on the nature of parasitic losses, overall thermal-to-electric conversion efficiencies greater than 20 percent are feasible.

High Efficiency Centrifugal Compressor for Rotorcraft Applications

NASA Technical Reports Server (NTRS)

Medic, Gorazd; Sharma, Om P.; Jongwook, Joo; Hardin, Larry W.; McCormick, Duane C.; Cousins, William T.; Lurie, Elizabeth A.; Shabbir, Aamir; Holley, Brian M.; Van Slooten, Paul R.

2017-01-01

The report "High Efficiency Centrifugal Compressor for Rotorcraft Applications" documents the work conducted at UTRC under the NRA Contract NNC08CB03C, with cost share 2/3 NASA, and 1/3 UTRC, that has been extended to 4.5 years. The purpose of this effort was to identify key technical barriers to advancing the state-of-the-art of small centrifugal compressor stages; to delineate the measurements required to provide insight into the flow physics of the technical barriers; to design, fabricate, install, and test a state-of-the-art research compressor that is representative of the rear stage of an axial-centrifugal aero-engine; and to acquire detailed aerodynamic performance and research quality data to clarify flow physics and to establish detailed data sets for future application. The design activity centered on meeting the goal set outlined in the NASA solicitation-the design target was to increase efficiency at higher work factor, while also reducing the maximum diameter of the stage. To fit within the existing Small Engine Components Test Facility at NASA Glenn Research Center (GRC) and to facilitate component re-use, certain key design parameters were fixed by UTRC, including impeller tip diameter, impeller rotational speed, and impeller inlet hub and shroud radii. This report describes the design effort of the High Efficiency Centrifugal Compressor stage (HECC) and delineation of measurements, fabrication of the compressor, and the initial tests that were performed. A new High-Efficiency Centrifugal Compressor stage with a very challenging reduction in radius ratio was successfully designed, fabricated and installed at GRC. The testing was successful, with no mechanical problems and the running clearances were achieved without impeller rubs. Overall, measured pressure ratio of 4.68, work factor of 0.81, and at design exit corrected flow rate of 3 lbm/s met the target requirements. Polytropic efficiency of 85.5 percent and stall margin of 7.5 percent were

High Efficiency Centrifugal Compressor for Rotorcraft Applications

NASA Technical Reports Server (NTRS)

Medic, Gorazd; Sharma, Om P.; Jongwook, Joo; Hardin, Larry W.; McCormick, Duane C.; Cousins, William T.; Lurie, Elizabeth A.; Shabbir, Aamir; Holley, Brian M.; Van Slooten, Paul R.

2014-01-01

The report "High Efficiency Centrifugal Compressor for Rotorcraft Applications" documents the work conducted at UTRC under the NRA Contract NNC08CB03C, with cost share 2/3 NASA, and 1/3 UTRC, that has been extended to 4.5 years. The purpose of this effort was to identify key technical barriers to advancing the state-of-the-art of small centrifugal compressor stages; to delineate the measurements required to provide insight into the flow physics of the technical barriers; to design, fabricate, install, and test a state-of-the-art research compressor that is representative of the rear stage of an axial-centrifugal aero-engine; and to acquire detailed aerodynamic performance and research quality data to clarify flow physics and to establish detailed data sets for future application. The design activity centered on meeting the goal set outlined in the NASA solicitation-the design target was to increase efficiency at higher work factor, while also reducing the maximum diameter of the stage. To fit within the existing Small Engine Components Test Facility at NASA Glenn Research Center (GRC) and to facilitate component re-use, certain key design parameters were fixed by UTRC, including impeller tip diameter, impeller rotational speed, and impeller inlet hub and shroud radii. This report describes the design effort of the High Efficiency Centrifugal Compressor stage (HECC) and delineation of measurements, fabrication of the compressor, and the initial tests that were performed. A new High-Efficiency Centrifugal Compressor stage with a very challenging reduction in radius ratio was successfully designed, fabricated and installed at GRC. The testing was successful, with no mechanical problems and the running clearances were achieved without impeller rubs. Overall, measured pressure ratio of 4.68, work factor of 0.81, and at design exit corrected flow rate of 3 lbm/s met the target requirements. Polytropic efficiency of 85.5 percent and stall margin of 7.5 percent were

Innovative manufacturing technologies for low-cost, high efficiency PERC-based PV modules

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yelundur, Vijay

2017-04-19

The goal this project was to accelerate the deployment of innovative solar cell and module technologies that reduce the cost of PERC-based modules to best-in-class. New module integration technology was to be used to reduce the cost and reliance on conventional silver bus bar pastes and enhance cell efficiency. On the cell manufacturing front, the cost of PERC solar cells was to be reduced by introducing advanced metallization approaches to increase cell efficiency. These advancements will be combined with process optimization to target cell efficiencies in the range of 21 to 21.5%. This project will also explore the viability ofmore » a bifacial PERC solar cell design to enable cost savings through the use of thin silicon wafers. This project was terminated on 4/30/17 after four months of activity due financial challenges facing the recipient.« less

Requirements for high-efficiency solar cells

NASA Technical Reports Server (NTRS)

Sah, C. T.

1986-01-01

Minimum recombination and low injection level are essential for high efficiency. Twenty percent AM1 efficiency requires a dark recombination current density of 2 x 10 to the minus 13th power A/sq cm and a recombination center density of less than 10 to the 10th power /cu cm. Recombination mechanisms at thirteen locations in a conventional single crystalline silicon cell design are reviewed. Three additional recombination locations are described at grain boundaries in polycrystalline cells. Material perfection and fabrication process optimization requirements for high efficiency are outlined. Innovative device designs to reduce recombination in the bulk and interfaces of single crystalline cells and in the grain boundary of polycrystalline cells are reviewed.

Thin-film semiconductor perspective of organometal trihalide perovskite materials for high-efficiency solar cells

DOE PAGES

Xiao, Zhengguo; Yuan, Yongbo; Wang, Qi; ...

2016-02-19

Organolead trihalide perovskites (OTPs) are arising as a new generation of low-cost active materials for solar cells with efficiency rocketing from 3.5% to over 20% within only five years. From “dye” in dye sensitized solar cells to “hole conductors” and “electron conductors” in mesoscopic heterojunction solar cells, there has been a dramatic conceptual evolution on the function of OTPs in photovoltaic devices. OTPs were originally used as dyes in Gratzel cells, achieving a high efficiency above 15% which, however, did not manifest the excellent charge transport properties of OTPs. An analogy of OTPs to traditional semiconductors was drawn after themore » demonstration of highly efficient planar heterojunction structure OTP devices and the observation of their excellent bipolar transport properties with a large diffusion length exceeding 100 nm in CH 3NH 3PbI 3 (MAPbI 3) polycrystalline thin films. Here, this review aims to provide the most recent advances in the understanding of the origin of the high OTP device efficiency. Specifically we will focus on reviewing the progress in understanding 1) the characterization of fantastic optoelectronic property of OTPs, 2) the unusual defect physics that originate the optoelectronic property; 3) morphology control of the perovskite film from fabrication process and film post-treatment, and 4) device interface and charge transport layers that dramatically impact device efficiency in the OTP thin film devices; 5) photocurrent hysteresis; 6) tandem solar cells; 7) stability of the perovskite materials and solar cell devices.« less

Advanced very high resolution radiometer

NASA Technical Reports Server (NTRS)

1976-01-01

The advanced very high resolution radiometer development program is considered. The program covered the design, construction, and test of a breadboard model, engineering model, protoflight model, mechanical structural model, and a life test model. Special bench test and calibration equipment was also developed for use on the program.

High efficiency vapor-fed AMTEC system for direct conversion. Final report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Anderson, W.G.; Bland, J.J.

1997-05-23

The Alkali Metal Thermal to Electric Converter (AMTEC) is a high temperature, high efficiency system for converting thermal to electrical energy, with no moving parts. It is based on the unique properties of {beta}{double_prime}-alumina solid electrolyte (BASE), which is an excellent conductor of sodium ions, but an extremely poor conductor of electrons. When the inside of the BASE is maintained at a higher temperature and pressure, a concentration gradient is created across the BASE. Electrons and sodium atoms cannot pass through the BASE. However, the sodium atoms are ionized, and the sodium ions move through the BASE to the lowermore » potential (temperature) region. The electrons travel externally to the AMTEC cell, providing power. There are a number of potential advantages to a wick-pumped, vapor-fed AMTEC system when compared with other designs. A wick-pumped system uses capillary forces to passively return liquid to the evaporator, and to distribute the liquid in the evaporator. Since the fluid return is self-regulating, multiple BASE tubes can use a single remote condenser, potentially improving efficiency in advanced AMTEC designs. Since the system is vapor-fed, sodium vapor is supplied at a uniform temperature and flux to the BASE tube, even with non-uniform heat fluxes and temperatures at the evaporator. The primary objective of the Phase 2 program was to develop wick-pumped AMTEC cells. During the program, procedures to fabricate wicks with smaller pore sizes were developed, to allow operation of an AMTEC cell at 800 C. A revised design was made for a High-Temperature, Wick-Fed AMTEC cell. In addition to the smaller wick pore size, several other changes were made to increase the cell efficiency: (1) internal artery return of condensate; (2) high temperature electrical feedthrough; and (3) separate heat pipe for providing heat to the BASE.« less

Overview of NASA's Supersonic Cruise Efficiency - Propulsion Research

NASA Technical Reports Server (NTRS)

DeBonis, James R.

2009-01-01

The research in Supersonic Cruise Efficiency Propulsion (SCE-P) Technical Challenge area of NASA's Supersonics project is discussed. The research in SCE-P is being performed to enable efficient supersonic flight over land. Research elements in this area include: Advance Inlet Concepts, High Performance/Wider Operability Fan and Compressor, Advanced Nozzle Concepts, and Intelligent Sensors/Actuators. The research under each of these elements is briefly discussed.

Projected techno-economic improvements for advanced solar thermal power plants

NASA Technical Reports Server (NTRS)

Fujita, T.; Manvi, R.; Roschke, E. J.

1979-01-01

The projected characteristics of solar thermal power plants (with outputs up to 10 MWe) employing promising advanced technology subsystems/components are compared to current (or pre-1985) steam-Rankine systems. Improvements accruing to advanced technology development options are delineated. The improvements derived from advanced systems result primarily from achieving high efficiencies via solar collector systems which (1) capture a large portion of the available insolation and (2) concentrate this captured solar flux to attain high temperatures required for high heat engine/energy conversion performance. The most efficient solar collector systems employ two-axis tracking. Attractive systems include the central receiver/heliostat and the parabolic dish.

High Efficiency Room Air Conditioner

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bansal, Pradeep

This project was undertaken as a CRADA project between UT-Battelle and Geberal Electric Company and was funded by Department of Energy to design and develop of a high efficiency room air conditioner. A number of novel elements were investigated to improve the energy efficiency of a state-of-the-art WAC with base capacity of 10,000 BTU/h. One of the major modifications was made by downgrading its capacity from 10,000 BTU/hr to 8,000 BTU/hr by replacing the original compressor with a lower capacity (8,000 BTU/hr) but high efficiency compressor having an EER of 9.7 as compared with 9.3 of the original compressor. However,more » all heat exchangers from the original unit were retained to provide higher EER. The other subsequent major modifications included- (i) the AC fan motor was replaced by a brushless high efficiency ECM motor along with its fan housing, (ii) the capillary tube was replaced with a needle valve to better control the refrigerant flow and refrigerant set points, and (iii) the unit was tested with a drop-in environmentally friendly binary mixture of R32 (90% molar concentration)/R125 (10% molar concentration). The WAC was tested in the environmental chambers at ORNL as per the design rating conditions of AHAM/ASHRAE (Outdoor- 95F and 40%RH, Indoor- 80F, 51.5%RH). All these modifications resulted in enhancing the EER of the WAC by up to 25%.« less

AVHRR/1-FM Advanced Very High Resolution Radiometer

NASA Technical Reports Server (NTRS)

1979-01-01

The advanced very high resolution radiometer is discussed. The program covers design, construction, and test of a breadboard model, engineering model, protoflight model, mechanical/structural model, and a life test model. Special bench test and calibration equipment was developed for use on the program. The flight model program objectives were to fabricate, assemble and test four of the advanced very high resolution radiometers along with a bench cooler and collimator.

Photon-trapping microstructures enable high-speed high-efficiency silicon photodiodes

NASA Astrophysics Data System (ADS)

Gao, Yang; Cansizoglu, Hilal; Polat, Kazim G.; Ghandiparsi, Soroush; Kaya, Ahmet; Mamtaz, Hasina H.; Mayet, Ahmed S.; Wang, Yinan; Zhang, Xinzhi; Yamada, Toshishige; Devine, Ekaterina Ponizovskaya; Elrefaie, Aly F.; Wang, Shih-Yuan; Islam, M. Saif

2017-04-01

High-speed, high-efficiency photodetectors play an important role in optical communication links that are increasingly being used in data centres to handle higher volumes of data traffic and higher bandwidths, as big data and cloud computing continue to grow exponentially. Monolithic integration of optical components with signal-processing electronics on a single silicon chip is of paramount importance in the drive to reduce cost and improve performance. We report the first demonstration of micro- and nanoscale holes enabling light trapping in a silicon photodiode, which exhibits an ultrafast impulse response (full-width at half-maximum) of 30 ps and a high efficiency of more than 50%, for use in data-centre optical communications. The photodiode uses micro- and nanostructured holes to enhance, by an order of magnitude, the absorption efficiency of a thin intrinsic layer of less than 2 µm thickness and is designed for a data rate of 20 gigabits per second or higher at a wavelength of 850 nm. Further optimization can improve the efficiency to more than 70%.

Advanced Natural Gas Reciprocating Engine(s)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pike, Edward

The objective of the Cummins ARES program, in partnership with the US Department of Energy (DOE), is to develop advanced natural gas engine technologies that increase engine system efficiency at lower emissions levels while attaining lower cost of ownership. The goals of the project are to demonstrate engine system achieving 50% Brake Thermal Efficiency (BTE) in three phases, 44%, 47% and 50% (starting baseline efficiency at 36% BTE) and 0.1 g/bhp-hr NOx system out emissions (starting baseline NOx emissions at 2 – 4 g/bhp-hr NOx). Primary path towards above goals include high Brake Mean Effective Pressure (BMEP), improved closed cyclemore » efficiency, increased air handling efficiency and optimized engine subsystems. Cummins has successfully demonstrated each of the phases of this program. All targets have been achieved through application of a combined set of advanced base engine technologies and Waste Heat Recovery from Charge Air and Exhaust streams, optimized and validated on the demonstration engine and other large engines. The following architectures were selected for each Phase: Phase 1: Lean Burn Spark Ignited (SI) Key Technologies: High Efficiency Turbocharging, Higher Efficiency Combustion System. In production on the 60/91L engines. Over 500MW of ARES Phase 1 technology has been sold. Phase 2: Lean Burn Technology with Exhaust Waste Heat Recovery (WHR) System Key Technologies: Advanced Ignition System, Combustion Improvement, Integrated Waste Heat Recovery System. Base engine technologies intended for production within 2 to 3 years Phase 3: Lean Burn Technology with Exhaust and Charge Air Waste Heat Recovery System Key Technologies: Lower Friction, New Cylinder Head Designs, Improved Integrated Waste Heat Recovery System. Intended for production within 5 to 6 years Cummins is committed to the launch of next generation of large advanced NG engines based on ARES technology to be commercialized worldwide.« less

HIGH EFFICIENCY SYNGAS GENERATION

DOE Office of Scientific and Technical Information (OSTI.GOV)

Robert J. Copeland; Yevgenia Gershanovich; Brian Windecker

2005-02-01

This project investigated an efficient and low cost method of auto-thermally reforming natural gas to hydrogen and carbon monoxide. Reforming is the highest cost step in producing products such as methanol and Fisher Tropsch liquids (i.e., gas to liquids); and reducing the cost of reforming is the key to reducing the cost of these products. Steam reforming is expensive because of the high cost of the high nickel alloy reforming tubes (i.e., indirectly fired reforming tubes). Conventional auto-thermal or Partial Oxidation (POX) reforming minimizes the size and cost of the reformers and provides a near optimum mixture of CO andmore » hydrogen. However POX requires pure oxygen, which consumes power and significantly increases the cost to reforming. Our high efficiency process extracts oxygen from low-pressure air with novel oxygen sorbent and transfers the oxygen to a nickel-catalyzed reformer. The syngas is generated at process pressure (typically 20 to 40 bar) without nitrogen dilution and has a 1CO to 2H{sub 2} ratio that is near optimum for the subsequent production of Fisher-Tropsch liquid to liquids and other chemicals (i.e., Gas to Liquids, GTL). Our high process efficiency comes from the way we transfer the oxygen into the reformer. All of the components of the process, except for the oxygen sorbent, are commonly used in commercial practice. A process based on a longlived, regenerable, oxygen transfer sorbent could substantially reduce the cost of natural gas reforming to syngas. Lower cost syngas (CO + 2H{sub 2}) that is the feedstock for GTL would reduce the cost of GTL and for other commercial applications (e.g., methanol, other organic chemicals). The vast gas resources of Alaska's North Slope (ANS) offer more than 22 Tcf of gas and GTL production in this application alone, and could account for as much as 300,000 to 700,000 bpd for 20 to 30+ years. We developed a new sorbent, which is an essential part of the High Efficiency Oxygen Process (HOP). We

The Physics of Advanced High-Gain Targets for Inertial Fusion Energy

NASA Astrophysics Data System (ADS)

Perkins, L. John

2010-11-01

In ca. 2011-2012, the National Ignition Facility is poised to demonstrate fusion ignition and gain in the laboratory for the first time. This key milestone in the development of inertial confinement fusion (ICF) can be expected to engender interest in the development of inertial fusion energy (IFE) and expanded efforts on a number of advanced targets that may achieve high fusion energy gain at lower driver energies. In this tutorial talk, we will discuss the physics underlying ICF ignition and thermonuclear burn, examine the requirements for high gain, and outline candidate R&D programs that will be required to assess the performance of these target concepts under various driver systems including lasers, heavy-ions and pulsed power. Such target concepts include those operating by fast ignition, shock ignition, impact ignition, dual-density, magnetically-insulated, one- and two-sided drive, etc., some of which may have potential to burn advanced, non-DT fusion fuels. We will then delineate the role of such targets in their application to the production of high average fusion power. Here, systems studies of IFE economics suggest that we should strive for target fusion gains of around 100 at drive energies of 1MJ, together with corresponding rep-rates of up to 10Hz and driver electrical efficiencies around 15%. In future years, there may be exciting opportunities to study such ``innovative confinement concepts'' with prospects of fielding them on facilities such as NIF to obtain high fusion energy gains on a single shot basis.

Capability of Rolling Efficiency for 100M High-Speed Rails

DOE Office of Scientific and Technical Information (OSTI.GOV)

Huang, Howard

2014-03-22

OG Technologies, Inc. (OGT), along with its academic and industrial partners, proposes this CORE project for the Capability of Rolling Efficiency for 100m high-speed rails. The goal is to establish the competitive advantage, and thus the sustainability of the US-based rail manufacturers by greatly enhanced efficiency through innovative in-line metrology technology, in-depth process knowledge, and advanced process control to overcome detrimental factors such as higher labor costs that are saddling the US manufacturing sector. This Phase I project was carried out by an industrial-academia team over 9 months. The R&D team successfully completed all technical tasks and accomplished the objectivesmore » for the Phase I. In addition to the technical efforts, the introductory information of this project as well as anticipated progress was disseminated to steel mills interested in the project. The Phase I project has established the technical and commercial basis for additional development. There are needs to further completing the in-line sensing capability, deepening the capability of metamodeling, and supporting the process monitoring and control. The R&D team plans to submit a Phase II proposal based on the findings.« less

High-efficiency chiral meta-lens.

PubMed

Groever, Benedikt; Rubin, Noah A; Mueller, J P Balthasar; Devlin, Robert C; Capasso, Federico

2018-05-08

We present here a compact metasurface lens element that enables simultaneous and spatially separated imaging of light of opposite circular polarization states. The design overcomes a limitation of previous chiral lenses reliant on the traditional geometric phase approach by allowing for independent focusing of both circular polarizations without a 50% efficiency trade-off. We demonstrate circular polarization-dependent imaging at visible wavelengths with polarization contrast greater than 20dB and efficiencies as high as 70%.

High speed research system study. Advanced flight deck configuration effects

NASA Technical Reports Server (NTRS)

Swink, Jay R.; Goins, Richard T.

1992-01-01

In mid-1991 NASA contracted with industry to study the high-speed civil transport (HSCT) flight deck challenges and assess the benefits, prior to initiating their High Speed Research Program (HSRP) Phase 2 efforts, then scheduled for FY-93. The results of this nine-month effort are presented, and a number of the most significant findings for the specified advanced concepts are highlighted: (1) a no nose-droop configuration; (2) a far forward cockpit location; and (3) advanced crew monitoring and control of complex systems. The results indicate that the no nose-droop configuration is critically dependent upon the design and development of a safe, reliable, and certifiable Synthetic Vision System (SVS). The droop-nose configuration would cause significant weight, performance, and cost penalties. The far forward cockpit location, with the conventional side-by-side seating provides little economic advantage; however, a configuration with a tandem seating arrangement provides a substantial increase in either additional payload (i.e., passengers) or potential downsizing of the vehicle with resulting increases in performance efficiencies and associated reductions in emissions. Without a droop nose, forward external visibility is negated and takeoff/landing guidance and control must rely on the use of the SVS. The technologies enabling such capabilities, which de facto provides for Category 3 all-weather operations on every flight independent of weather, represent a dramatic benefits multiplier in a 2005 global ATM network: both in terms of enhanced economic viability and environmental acceptability.

Advanced Techniques for Deploying Reliable and Efficient Access Control: Application to E-healthcare.

PubMed

Jaïdi, Faouzi; Labbene-Ayachi, Faten; Bouhoula, Adel

2016-12-01

Nowadays, e-healthcare is a main advancement and upcoming technology in healthcare industry that contributes to setting up automated and efficient healthcare infrastructures. Unfortunately, several security aspects remain as main challenges towards secure and privacy-preserving e-healthcare systems. From the access control perspective, e-healthcare systems face several issues due to the necessity of defining (at the same time) rigorous and flexible access control solutions. This delicate and irregular balance between flexibility and robustness has an immediate impact on the compliance of the deployed access control policy. To address this issue, the paper defines a general framework to organize thinking about verifying, validating and monitoring the compliance of access control policies in the context of e-healthcare databases. We study the problem of the conformity of low level policies within relational databases and we particularly focus on the case of a medical-records management database defined in the context of a Medical Information System. We propose an advanced solution for deploying reliable and efficient access control policies. Our solution extends the traditional lifecycle of an access control policy and allows mainly managing the compliance of the policy. We refer to an example to illustrate the relevance of our proposal.

Theoretical study of the design and performance of a high-gain, high-extraction-efficiency FEL oscillator

DOE Office of Scientific and Technical Information (OSTI.GOV)

Goldstein, J.; Nguyen, D.C.; Sheffield, R.L.

1996-10-01

We present the results of theoretical and simulation studies of the design and performance of a new F type of FEL oscillator. This device, known by the acronym RAFEL for Regenerative Amplifier Free-Electron Laser, will be constructed in the space presently occupied by the AFEL (Advanced FEL) at Los Alamos, and will be driven by an upgraded (to higher average power) version of the present AFEL linac. In order to achieve a long-time-averaged optical output power of {approximately} 1 kW using an electron beam with an average power of {approximately} 20 kW, a rather high extraction efficiency {eta} {approximately} 5%more » is required. We have designed a 2-m-long undulator to attain this goal: the first meter is untapered and provides high gain while the second meter is linearly-tapered in magnetic field amplitude to provide high extraction efficiency in the standard K-M-R manner. Two-plane focusing and linear polarization of the undulator are assumed. Electron-beam properties from PARMEIA simulations of the AFEL accelerator were used in the design. A large saturated gain, {approximately} 500, requires a very small optical feedback to keep the device operating at steady-state. However, the large gain leads to distorted optical modes which require two- and three-dimensional simulations to adequately treat diffraction effects. This FEL will be driven by 17 MeV electrons and will operate in the 16 {mu}m spectral region.« less

US Department of Energy`s high-temperature and high-pressure particulate cleanup for advanced coal-based power systems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dennis, R.A.

1997-05-01

The availability of reliable, low-cost electricity is a cornerstone for the United States` ability to compete in the world market. The Department of Energy (DOE) projects the total consumption of electricity in the US to rise from 2.7 trillion kilowatt-hours in 1990 to 3.5 trillion in 2010. Although energy sources are diversifying, fossil fuel still produces 90 percent of the nation`s energy. Coal is our most abundant fossil fuel resource and the source of 56 percent of our electricity. It has been the fuel of choice because of its availability and low cost. A new generation of high-efficiency power systemsmore » has made it possible to continue the use of coal while still protecting the environment. Such power systems greatly reduce the pollutants associated with cola-fired plants built before the 1970s. To realize this high efficiency and superior environmental performance, advanced coal-based power systems will require gas stream cleanup under high-temperature and high-pressure (HTHP) process conditions. Presented in this paper are the HTHP particulate capture requirements for the Integrated Gasification Combined Cycle (IGCC) and Pressurized Fluidized-Bed Combustion (PFBC) power systems, the HTHP particulate cleanup systems being implemented in the PFBC and IGCC Clean Coal Technology (CCT) Projects, and the currently available particulate capture performance results.« less

Highly efficient monolithic dye-sensitized solar cells.

PubMed

Kwon, Jeong; Park, Nam-Gyu; Lee, Jun Young; Ko, Min Jae; Park, Jong Hyeok

2013-03-01

Monolithic dye-sensitized solar cells (M-DSSCs) provide an effective way to reduce the fabrication cost of general DSSCs since they do not require transparent conducting oxide substrates for the counter electrode. However, conventional monolithic devices have low efficiency because of the impediments resulting from counter electrode materials and spacer layers. Here, we demonstrate highly efficient M-DSSCs featuring a highly conductive polymer combined with macroporous polymer spacer layers. With M-DSSCs based on a PEDOT/polymer spacer layer, a power conversion efficiency of 7.73% was achieved, which is, to the best of our knowledge, the highest efficiency for M-DSSCs to date. Further, PEDOT/polymer spacer layers were applied to flexible DSSCs and their cell performance was investigated.

Technology Development for High Efficiency Optical Communications

NASA Technical Reports Server (NTRS)

Farr, William H.

2012-01-01

Deep space optical communications is a significantly more challenging operational domain than near Earth space optical communications, primarily due to effects resulting from the vastly increased range between transmitter and receiver. The NASA Game Changing Development Program Deep Space Optical Communications Project is developing four key technologies for the implementation of a high efficiency telecommunications system that will enable greater than 10X the data rate of a state-of-the-art deep space RF system (Ka-band) for similar transceiver mass and power burden on the spacecraft. These technologies are a low mass spacecraft disturbance isolation assembly, a flight qualified photon counting detector array, a high efficiency flight laser amplifier and a high efficiency photon counting detector array for the ground-based receiver.

Advanced aerodynamics. Selected NASA research

NASA Technical Reports Server (NTRS)

1981-01-01

This Conference Publication contains selected NASA papers that were presented at the Fifth Annual Status Review of the NASA Aircraft Energy Efficiency (ACEE) Energy Efficient Transport (EET) Program held at Dryden Flight Research Center in Edwards, California on September 14 to 15, 1981. These papers describe the status of several NASA in-house research activities in the areas of advanced turboprops, natural laminar flow, oscillating control surfaces, high-Reynolds-number airfoil tests, high-lift technology, and theoretical design techniques.

Advanced Wear-resistant Nanocomposites for Increased Energy Efficiency

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cook, B. A.; Harringa, J. L.; Russel, A. M.

This report summarizes the work performed by an Ames-led project team under a 4-year DOE-ITP sponsored project titled, 'Advanced Wear-resistant Nanocomposites for Increased Energy Efficiency.' The Report serves as the project deliverable for the CPS agreement number 15015. The purpose of this project was to develop and commercialize a family of lightweight, bulk composite materials that are highly resistant to degradation by erosive and abrasive wear. These materials, based on AlMgB{sub 14}, are projected to save over 30 TBtu of energy per year when fully implemented in industrial applications, with the associated environmental benefits of eliminating the burning of 1.5more » M tons/yr of coal and averting the release of 4.2 M tons/yr of CO{sub 2} into the air. This program targeted applications in the mining, drilling, machining, and dry erosion applications as key platforms for initial commercialization, which includes some of the most severe wear conditions in industry. Production-scale manufacturing of this technology has begun through a start-up company, NewTech Ceramics (NTC). This project included providing technical support to NTC in order to facilitate cost-effective mass production of the wear-resistant boride components. Resolution of issues related to processing scale-up, reduction in energy intensity during processing, and improving the quality and performance of the composites, without adding to the cost of processing were among the primary technical focus areas of this program. Compositional refinements were also investigated in order to achieve the maximum wear resistance. In addition, synthesis of large-scale, single-phase AlMgB{sub 14} powder was conducted for use as PVD sputtering targets for nanocoating applications.« less

Iridoids from Carbohydrates via Pauson-Khand Reaction: Synthesis of Advanced Highly Oxygenated Cyclopentane-Annulated Pyranosides from D-Glucal Derivatives.

PubMed

Marco-Contelles, José; Ruiz-Caro, Juliana

1999-10-29

The Pauson-Khand reaction on suitable 4-oxa-hept-1-en-6-ynes (1, 17) obtained from 3,4,6-tri-O-acetyl-D-glucal gives the cyclopentane-annulated pyranosides (2, 18) that can be efficiently and stereoselectivelly transformed into chiral, advanced, highly oxygenated intermediates (10, 16, 24) for the synthesis of iridoid aglycones.

Code TESLA for Modeling and Design of High-Power High-Efficiency Klystrons

DTIC Science & Technology

2011-03-01

CODE TESLA FOR MODELING AND DESIGN OF HIGH - POWER HIGH -EFFICIENCY KLYSTRONS * I.A. Chernyavskiy, SAIC, McLean, VA 22102, U.S.A. S.J. Cooke, B...and multiple-beam klystrons as high - power RF sources. These sources are widely used or proposed to be used in accelerators in the future. Comparison...of TESLA modelling results with experimental data for a few multiple-beam klystrons are shown. INTRODUCTION High - power and high -efficiency

High efficiency novel window air conditioner

DOE PAGES

Bansal, Pradeep

2015-07-24

This paper presents the technical development of a high efficiency window air conditioner. In order to achieve higher energy efficiency ratio (EER), the original capacity of the R410A unit was downgraded by replacing the original compressor with a lower capacity but higher EER compressor, while all heat exchangers and the chassis from the original unit were retained. The other subsequent major modifications included – the AC fan motor being replaced with a brushless high efficiency electronically commuted motor (ECM) motor, the capillary tube being replaced with a needle valve to better control the refrigerant flow and refrigerant set points, andmore » R410A being replaced with drop-in environmentally friendly binary mixture of R32 (85% molar concentration)/R125 (15% molar concentration). All these modifications resulted in significant EER enhancement of the modified unit.« less

High efficiency novel window air conditioner

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bansal, Pradeep

This paper presents the technical development of a high efficiency window air conditioner. In order to achieve higher energy efficiency ratio (EER), the original capacity of the R410A unit was downgraded by replacing the original compressor with a lower capacity but higher EER compressor, while all heat exchangers and the chassis from the original unit were retained. The other subsequent major modifications included – the AC fan motor being replaced with a brushless high efficiency electronically commuted motor (ECM) motor, the capillary tube being replaced with a needle valve to better control the refrigerant flow and refrigerant set points, andmore » R410A being replaced with drop-in environmentally friendly binary mixture of R32 (85% molar concentration)/R125 (15% molar concentration). All these modifications resulted in significant EER enhancement of the modified unit.« less

Development and characterization of high-efficiency, high-specific impulse xenon Hall thrusters

NASA Astrophysics Data System (ADS)

Hofer, Richard Robert

This dissertation presents research aimed at extending the efficient operation of 1600 s specific impulse Hall thruster technology to the 2000--3000 s range. While recent studies of commercially developed Hall thrusters demonstrated greater than 4000 s specific impulse, maximum efficiency occurred at less than 3000 s. It was hypothesized that the efficiency maximum resulted as a consequence of modern magnetic field designs, optimized for 1600 s, which were unsuitable at high-specific impulse. Motivated by the industry efforts and mission studies, the aim of this research was to develop and characterize xenon Hall thrusters capable of both high-specific impulse and high-efficiency operation. The research divided into development and characterization phases. During the development phase, the laboratory-model NASA-173M Hall thrusters were designed with plasma lens magnetic field topographies and their performance and plasma characteristics were evaluated. Experiments with the NASA-173M version 1 (v1) validated the plasma lens design by showing how changing the magnetic field topography at high-specific impulse improved efficiency. Experiments with the NASA-173M version 2 (v2) showed there was a minimum current density and optimum magnetic field topography at which efficiency monotonically increased with voltage. Between 300--1000 V, total specific impulse and total efficiency of the NASA-173Mv2 operating at 10 mg/s ranged from 1600--3400 s and 51--61%, respectively. Comparison of the thrusters showed that efficiency can be optimized for specific impulse by varying the plasma lens design. During the characterization phase, additional plasma properties of the NASA-173Mv2 were measured and a performance model was derived accounting for a multiply-charged, partially-ionized plasma. Results from the model based on experimental data showed how efficient operation at high-specific impulse was enabled through regulation of the electron current with the magnetic field. The

Advances in highly doped upconversion nanoparticles.

PubMed

Wen, Shihui; Zhou, Jiajia; Zheng, Kezhi; Bednarkiewicz, Artur; Liu, Xiaogang; Jin, Dayong

2018-06-20

Lanthanide-doped upconversion nanoparticles (UCNPs) are capable of converting near-infra-red excitation into visible and ultraviolet emission. Their unique optical properties have advanced a broad range of applications, such as fluorescent microscopy, deep-tissue bioimaging, nanomedicine, optogenetics, security labelling and volumetric display. However, the constraint of concentration quenching on upconversion luminescence has hampered the nanoscience community to develop bright UCNPs with a large number of dopants. This review surveys recent advances in developing highly doped UCNPs, highlights the strategies that bypass the concentration quenching effect, and discusses new optical properties as well as emerging applications enabled by these nanoparticles.

A high-efficiency high-power-generation system for automobiles

DOE Office of Scientific and Technical Information (OSTI.GOV)

Naidu, M.; Boules, N.; Henry, R.

This paper presents a new scheme for the efficient generation of high electric power demanded for future automobiles. The new system consists of a permanent-magnet (PM) alternator having high-energy MAGNEQUENCH (MQ) magnets and split winding and a novel electronic voltage-regulation scheme. A proof-of-concept system, capable of providing 100/250 A (idle/cruising) at 14 V, has been built and tested in the laboratory with encouraging results. This high output is provided at 15--20 percentage points higher efficiencies than conventional automotive alternators, which translates into considerable fuel economy savings. The system is 8 dB quieter and has a rotor inertia of only 2/3more » that of an equivalent production alternator, thus allowing for a belt drive without excessive slippage.« less

A high-efficiency, high power generation system for automobiles

DOE Office of Scientific and Technical Information (OSTI.GOV)

Naidu, M.; Boules, N.; Henry, R.

The paper presents a new scheme for the efficient generation of high electric power, demands for future automobiles. The new system, consists of a permanent magnet (PM) alternator having high energy MAGNEQUENCH (MQ) magnets and split winding; and a novel electronic voltage regulation scheme. A proof of concept system, capable of providing 100/250 A (idle/cruising) at 14 V, has been built and tested in the laboratory with encouraging results. This high output is provided at 15--20 percentage points higher efficiencies than conventional automotive alternators, which translates into considerable fuel economy savings. The system is 8 dB quieter and has amore » rotor inertia of only 2/3 that of an equivalent production alternator, thus allowing for a belt drive without excessive slippage.« less

Overview of Heat Addition and Efficiency Predictions for an Advanced Stirling Convertor

NASA Technical Reports Server (NTRS)

Wilson, Scott D.; Reid, Terry V.; Schifer, Nicholas A.; Briggs, Maxwell H.

2012-01-01

The U.S. Department of Energy (DOE) and Lockheed Martin Space Systems Company (LMSSC) have been developing the Advanced Stirling Radioisotope Generator (ASRG) for use as a power system for space science missions. This generator would use two high-efficiency Advanced Stirling Convertors (ASCs), developed by Sunpower Inc. and NASA Glenn Research Center (GRC). The ASCs convert thermal energy from a radioisotope heat source into electricity. As part of ground testing of these ASCs, different operating conditions are used to simulate expected mission conditions. These conditions require achieving a particular operating frequency, hot end and cold end temperatures, and specified electrical power output for a given net heat input. Microporous bulk insulation is used in the ground support test hardware to minimize the loss of thermal energy from the electric heat source to the environment. The insulation package is characterized before operation to predict how much heat will be absorbed by the convertor and how much will be lost to the environment during operation. In an effort to validate these predictions, numerous tasks have been performed, which provided a more accurate value for net heat input into the ASCs. This test and modeling effort included: (a) making thermophysical property measurements of test setup materials to provide inputs to the numerical models, (b) acquiring additional test data that was collected during convertor tests to provide numerical models with temperature profiles of the test setup via thermocouple and infrared measurements, (c) using multidimensional numerical models (computational fluid dynamics code) to predict net heat input of an operating convertor, and (d) using validation test hardware to provide direct comparison of numerical results and validate the multidimensional numerical models used to predict convertor net heat input. This effort produced high fidelity ASC net heat input predictions, which were successfully validated using

High-efficiency white OLEDs based on small molecules

NASA Astrophysics Data System (ADS)

Hatwar, Tukaram K.; Spindler, Jeffrey P.; Ricks, M. L.; Young, Ralph H.; Hamada, Yuuhiko; Saito, N.; Mameno, Kazunobu; Nishikawa, Ryuji; Takahashi, Hisakazu; Rajeswaran, G.

2004-02-01

Eastman Kodak Company and SANYO Electric Co., Ltd. recently demonstrated a 15" full-color, organic light-emitting diode display (OLED) using a high-efficiency white emitter combined with a color-filter array. Although useful for display applications, white emission from organic structures is also under consideration for other applications, such as solid-state lighting, where high efficiency and good color rendition are important. By incorporating adjacent blue and orange emitting layers in a multi-layer structure, highly efficient, stable white emission has been attained. With suitable host and dopant combinations, a luminance yield of 20 cd/A and efficiency of 8 lm/W have been achieved at a drive voltage of less than 8 volts and luminance level of 1000 cd/m2. The estimated external efficiency of this device is 6.3% and a high level of operational stability is observed. To our knowledge, this is the highest performance reported so far for white organic electroluminescent devices. We will review white OLED technology and discuss the fabrication and operating characteristics of these devices.

Ceramic applications in the advanced Stirling automotive engine

NASA Technical Reports Server (NTRS)

Tomazic, W. A.; Cairelli, J. E.

1977-01-01

The ideal cycle, its application to a practical machine, and the specific advantages of high efficiency, low emissions, multi-fuel capability, and low noise of the stirling engine are discussed. Certain portions of the Stirling engine must operate continuously at high temperature. Ceramics offer the potential of cost reduction and efficiency improvement for advanced engine applications. Potential applications for ceramics in Stirling engines, and some of the special problems pertinent to using ceramics in the Stirling engine are described. The research and technology program in ceramics which is planned to support the development of advanced Stirling engines is outlined.

High efficiency direct thermal to electric energy conversion from radioisotope decay using selective emitters and spectrally tuned solar cells

NASA Technical Reports Server (NTRS)

Chubb, Donald L.; Flood, Dennis J.; Lowe, Roland A.

1993-01-01

Thermophotovoltaic (TPV) systems are attractive possibilities for direct thermal-to-electric energy conversion, but have typically required the use of black body radiators operating at high temperatures. Recent advances in both the understanding and performance of solid rare-earth oxide selective emitters make possible the use of TPV at temperatures as low as 1200K. Both selective emitter and filter system TPV systems are feasible. However, requirements on the filter system are severe in order to attain high efficiency. A thin-film of a rare-earth oxide is one method for producing an efficient, rugged selective emitter. An efficiency of 0.14 and power density of 9.2 W/KG at 1200K is calculated for a hypothetical thin-film neodymia (Nd2O3) selective emitter TPV system that uses radioisotope decay as the thermal energy source.

The Series Connected Buck Boost Regulator Concept for High Efficiency Light Weight DC Voltage Regulation

NASA Technical Reports Server (NTRS)

Birchenough, Arthur G.

2003-01-01

Improvements in the efficiency and size of DC-DC converters have resulted from advances in components, primarily semiconductors, and improved topologies. One topology, which has shown very high potential in limited applications, is the Series Connected Boost Unit (SCBU), wherein a small DC-DC converter output is connected in series with the input bus to provide an output voltage equal to or greater than the input voltage. Since the DC-DC converter switches only a fraction of the power throughput, the overall system efficiency is very high. But this technique is limited to applications where the output is always greater than the input. The Series Connected Buck Boost Regulator (SCBBR) concept extends partial power processing technique used in the SCBU to operation when the desired output voltage is higher or lower than the input voltage, and the implementation described can even operate as a conventional buck converter to operate at very low output to input voltage ratios. This paper describes the operation and performance of an SCBBR configured as a bus voltage regulator providing 50 percent voltage regulation range, bus switching, and overload limiting, operating above 98 percent efficiency. The technique does not provide input-output isolation.

Development of Advanced Thermal and Environmental Barrier Coatings Using a High-Heat-Flux Testing Approach

NASA Technical Reports Server (NTRS)

Zhu, Dongming; Miller, Robert A.

2003-01-01

The development of low conductivity, robust thermal and environmental barrier coatings requires advanced testing techniques that can accurately and effectively evaluate coating thermal conductivity and cyclic resistance at very high surface temperatures (up to 1700 C) under large thermal gradients. In this study, a laser high-heat-flux test approach is established for evaluating advanced low conductivity, high temperature capability thermal and environmental barrier coatings under the NASA Ultra Efficient Engine Technology (UEET) program. The test approach emphasizes the real-time monitoring and assessment of the coating thermal conductivity, which initially rises under the steady-state high temperature thermal gradient test due to coating sintering, and later drops under the cyclic thermal gradient test due to coating cracking/delamination. The coating system is then evaluated based on damage accumulation and failure after the combined steady-state and cyclic thermal gradient tests. The lattice and radiation thermal conductivity of advanced ceramic coatings can also be evaluated using laser heat-flux techniques. The external radiation resistance of the coating is assessed based on the measured specimen temperature response under a laser- heated intense radiation-flux source. The coating internal radiation contribution is investigated based on the measured apparent coating conductivity increases with the coating surface test temperature under large thermal gradient test conditions. Since an increased radiation contribution is observed at these very high surface test temperatures, by varying the laser heat-flux and coating average test temperature, the complex relation between the lattice and radiation conductivity as a function of surface and interface test temperature may be derived.

Fused-core particle technology as an alternative to sub-2-microm particles to achieve high separation efficiency with low backpressure.

PubMed

Cunliffe, Jennifer M; Maloney, Todd D

2007-12-01

Fused-Core particles have recently been introduced as an alternative to using sub-2-microm particles in chromatographic separations. Fused-Core particles are composed of a 1.7 microm solid core surrounded by a 0.5 microm porous silica layer (d(p) = 2.7 microm) to reduce mass transfer and increase peak efficiency. The performance of two commercially available Fused-Core particles (Advanced Materials Technology Halo C18 and Supelco Ascentis Express C18) was compared with sub-2-microm particles from Waters, Agilent, and Thermo Scientific. Although the peak efficiencies were only approximately 80% of those obtained by the Waters Acquity particles, the 50% lower backpressure allowed columns to be coupled in series to increase peak efficiency to 92,750 plates. The low backpressure and high efficiencies of the Fused-Core particles offer a viable alternative to using sub-2-microm particles and very-high-pressure LC instrumentation.

Toward high-energy-density, high-efficiency, and moderate-temperature chip-scale thermophotovoltaics

PubMed Central

Chan, Walker R.; Bermel, Peter; Pilawa-Podgurski, Robert C. N.; Marton, Christopher H.; Jensen, Klavs F.; Senkevich, Jay J.; Joannopoulos, John D.; Soljačić, Marin; Celanovic, Ivan

2013-01-01

The challenging problem of ultra-high-energy-density, high-efficiency, and small-scale portable power generation is addressed here using a distinctive thermophotovoltaic energy conversion mechanism and chip-based system design, which we name the microthermophotovoltaic (μTPV) generator. The approach is predicted to be capable of up to 32% efficient heat-to-electricity conversion within a millimeter-scale form factor. Although considerable technological barriers need to be overcome to reach full performance, we have performed a robust experimental demonstration that validates the theoretical framework and the key system components. Even with a much-simplified μTPV system design with theoretical efficiency prediction of 2.7%, we experimentally demonstrate 2.5% efficiency. The μTPV experimental system that was built and tested comprises a silicon propane microcombustor, an integrated high-temperature photonic crystal selective thermal emitter, four 0.55-eV GaInAsSb thermophotovoltaic diodes, and an ultra-high-efficiency maximum power-point tracking power electronics converter. The system was demonstrated to operate up to 800 °C (silicon microcombustor temperature) with an input thermal power of 13.7 W, generating 344 mW of electric power over a 1-cm2 area. PMID:23440220

Diboron compound-based organic light-emitting diodes with high efficiency and reduced efficiency roll-off

NASA Astrophysics Data System (ADS)

Wu, Tien-Lin; Huang, Min-Jie; Lin, Chih-Chun; Huang, Pei-Yun; Chou, Tsu-Yu; Chen-Cheng, Ren-Wu; Lin, Hao-Wu; Liu, Rai-Shung; Cheng, Chien-Hong

2018-04-01

Organic light-emitting diodes (OLEDs) based on thermally activated delayed fluorescence (TADF) materials are promising for the realization of highly efficient light emitters. However, such devices have so far suffered from efficiency roll-off at high luminance. Here, we report the design and synthesis of two diboron-based molecules, CzDBA and tBuCzDBA, which show excellent TADF properties and yield efficient OLEDs with very low efficiency roll-off. These donor-acceptor-donor (D-A-D) type and rod-like compounds concurrently generate TADF with a photoluminescence quantum yield of 100% and an 84% horizontal dipole ratio in the thin film. A green OLED based on CzDBA exhibits a high external quantum efficiency of 37.8 ± 0.6%, a current efficiency of 139.6 ± 2.8 cd A-1 and a power efficiency of 121.6 ± 3.1 lm W-1 with an efficiency roll-off of only 0.3% at 1,000 cd m-2. The device has a peak emission wavelength of 528 nm and colour coordinates of the Commission International de ĺEclairage (CIE) of (0.31, 0.61), making it attractive for colour-display applications.

Superstructure high efficiency photovoltaics

NASA Technical Reports Server (NTRS)

Wagner, M.; So, L. C.; Leburton, J. P.

1987-01-01

A novel class of photovoltaic cascade structures is introduced which features multijunction upper subcells. These superstructure high efficiency photovoltaics (SHEP's) exhibit enhanced upper subcell spectral response because of the additional junctions which serve to reduce bulk recombination losses by decreasing the mean collection distance for photogenerated minority carriers. Two possible electrical configurations were studied and compared: a three-terminal scheme that allows both subcells to be operated at their individual maximum power points and a two-terminal configuration with an intercell ohmic contact for series interconnection. The three-terminal devices were found to be superior both in terms of beginning-of-life expectancy and radiation tolerance. Realistic simulations of three-terminal AlGaAs/GaAs SHEP's show that one sun AMO efficiencies in excess of 26 percent are possible.

A Versatile Molecular Design for High-Performance Nondoped OLEDs with ~100% Exciton Utilization and Negligible Efficiency Roll-Off.

PubMed

Liu, Huijun; Zeng, Jiajie; Guo, Jingjing; Nie, Han; Zhao, Zujin; Tang, Ben Zhong

2018-06-01

Nondoped organic light-emitting diodes (OLEDs) possess merits of higher stability and easier fabrication than doped devices. However, luminescent materials with high exciton utilization are generally unsuitable for nondoped OLEDs because of severe emission quenching and exciton annihilation in neat films. Herein, we wish to report a novel molecular design of integrating aggregation-induced delayed fluorescence (AIDF) moiety within host materials to explore efficient luminogens for nondoped OLEDs. By grafting 4-(phenoxazin-10-yl)benzoyl to common host materials, we develop a series of new luminescent materials with prominent AIDF property. Their neat films fluoresce strongly and can fully harvest both singlet and triplet excitons with suppressed exciton annihilation. Nondoped OLEDs of these AIDF luminogens exhibit excellent luminance (~100000 cd m-2), outstanding external quantum efficiencies (22.1-22.6%), negligible efficiency roll-off and improved operational stability. To the best of our knowledge, these are the most efficient nondoped OLEDs reported so far. This convenient and versatile molecular design is of high significance for the advance of nondoped OLEDs. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

High efficiency endocrine operation protocol: From design to implementation.

PubMed

Mascarella, Marco A; Lahrichi, Nadia; Cloutier, Fabienne; Kleiman, Simcha; Payne, Richard J; Rosenberg, Lawrence

2016-10-01

We developed a high efficiency endocrine operative protocol based on a mathematical programming approach, process reengineering, and value-stream mapping to increase the number of operations completed per day without increasing operating room time at a tertiary-care, academic center. Using this protocol, a case-control study of 72 patients undergoing endocrine operation during high efficiency days were age, sex, and procedure-matched to 72 patients undergoing operation during standard days. The demographic profile, operative times, and perioperative complications were noted. The average number of cases per 8-hour workday in the high efficiency and standard operating rooms were 7 and 5, respectively. Mean procedure times in both groups were similar. The turnaround time (mean ± standard deviation) in the high efficiency group was 8.5 (±2.7) minutes as compared with 15.4 (±4.9) minutes in the standard group (P < .001). Transient postoperative hypocalcemia was 6.9% (5/72) and 8.3% (6/72) for the high efficiency and standard groups, respectively (P = .99). In this study, patients undergoing high efficiency endocrine operation had similar procedure times and perioperative complications compared with the standard group. The proposed high efficiency protocol seems to better utilize operative time and decrease the backlog of patients waiting for endocrine operation in a country with a universal national health care program. Copyright © 2016 Elsevier Inc. All rights reserved.

Energy efficient engine fan component detailed design report

NASA Technical Reports Server (NTRS)

Halle, J. E.; Michael, C. J.

1981-01-01

The fan component which was designed for the energy efficient engine is an advanced high performance, single stage system and is based on technology advancements in aerodynamics and structure mechanics. Two fan components were designed, both meeting the integrated core/low spool engine efficiency goal of 84.5%. The primary configuration, envisioned for a future flight propulsion system, features a shroudless, hollow blade and offers a predicted efficiency of 87.3%. A more conventional blade was designed, as a back up, for the integrated core/low spool demonstrator engine. The alternate blade configuration has a predicted efficiency of 86.3% for the future flight propulsion system. Both fan configurations meet goals established for efficiency surge margin, structural integrity and durability.

Advanced Biology [Sahuarita High School Career Curriculum Project.

ERIC Educational Resources Information Center

Christensen, Larry

This course in advanced biology is entitled "Advanced Genetics" and is one of a series of instructional guides prepared by teachers for the Sahuarita High School (Arizona) Career Curriculum Project. It consists of seven units of study, and 15 behavioral objectives relating to these units are stated. The topics covered include a review of genetics,…

Enabling High Efficiency Nanoplasmonics with Novel Nanoantenna Architectures

PubMed Central

Cohen, Moshik; Shavit, Reuven; Zalevsky, Zeev

2015-01-01

Surface plasmon polaritons (SPPs) are propagating excitations that arise from coupling of light with collective electron oscillations. Characterized by high field intensity and nanometric dimensions, SPPs fashion rapid expansion of interest from fundamental and applicative perspectives. However, high metallic losses at optical frequencies still make nanoplasmonics impractical when high absolute efficiency is paramount, with major challenge is efficient plasmon generation in deep nanoscale. Here we introduce the Plantenna, the first reported nanodevice with the potential of addressing these limitations utilizing novel plasmonic architecture. The Plantenna has simple 2D structure, ultracompact dimensions and is fabricated on Silicon chip for future CMOS integration. We design the Plantenna to feed channel (20 nm × 20 nm) nanoplasmonic waveguides, achieving 52% coupling efficiency with Plantenna dimensions of λ3/17,000. We theoretically and experimentally show that the Plantenna enormously outperforms dipole couplers, achieving 28 dB higher efficiency with broad polarization diversity and huge local field enhancement. Our findings confirm the Plantenna as enabling device for high efficiency plasmonic technologies such as quantum nanoplasmonics, molecular strong coupling and plasmon nanolasers. PMID:26620270

Simple Motor Control Concept Results High Efficiency at High Velocities

NASA Astrophysics Data System (ADS)

Starin, Scott; Engel, Chris

2013-09-01

The need for high velocity motors in space applications for reaction wheels and detectors has stressed the limits of Brushless Permanent Magnet Motors (BPMM). Due to inherent hysteresis core losses, conventional BPMMs try to balance the need for torque verses hysteresis losses. Cong-less motors have significantly less hysteresis losses but suffer from lower efficiencies. Additionally, the inherent low inductance in cog-less motors result in high ripple currents or high switching frequencies, which lowers overall efficiency and increases performance demands on the control electronics.However, using a somewhat forgotten but fully qualified technology of Isotropic Magnet Motors (IMM), extremely high velocities may be achieved at low power input using conventional drive electronics. This paper will discuss the trade study efforts and empirical test data on a 34,000 RPM IMM.

RECENT ADVANCES IN HIGH TEMPERATURE ELECTROLYSIS AT IDAHO NATIONAL LABORATORY: STACK TESTS

DOE Office of Scientific and Technical Information (OSTI.GOV)

X, Zhang; J. E. O'Brien; R. C. O'Brien

2012-07-01

High temperature steam electrolysis is a promising technology for efficient sustainable large-scale hydrogen production. Solid oxide electrolysis cells (SOECs) are able to utilize high temperature heat and electric power from advanced high-temperature nuclear reactors or renewable sources to generate carbon-free hydrogen at large scale. However, long term durability of SOECs needs to be improved significantly before commercialization of this technology. A degradation rate of 1%/khr or lower is proposed as a threshold value for commercialization of this technology. Solid oxide electrolysis stack tests have been conducted at Idaho National Laboratory to demonstrate recent improvements in long-term durability of SOECs. Electrolytesupportedmore » and electrode-supported SOEC stacks were provided by Ceramatec Inc., Materials and Systems Research Inc. (MSRI), and Saint Gobain Advanced Materials (St. Gobain), respectively for these tests. Long-term durability tests were generally operated for a duration of 1000 hours or more. Stack tests based on technology developed at Ceramatec and MSRI have shown significant improvement in durability in the electrolysis mode. Long-term degradation rates of 3.2%/khr and 4.6%/khr were observed for MSRI and Ceramatec stacks, respectively. One recent Ceramatec stack even showed negative degradation (performance improvement) over 1900 hours of operation. A three-cell short stack provided by St. Gobain, however, showed rapid degradation in the electrolysis mode. Improvements on electrode materials, interconnect coatings, and electrolyteelectrode interface microstructures contribute to better durability of SOEC stacks.« less

Highly efficient and high-power diode-pumped femtosecond Yb:LYSO laser

NASA Astrophysics Data System (ADS)

Tian, Wenlong; Wang, Zhaohua; Zhu, Jiangfeng; Zheng, Lihe; Xu, Jun; Wei, Zhiyi

2017-04-01

A diode-pumped high-power femtosecond Yb:LYSO laser with high efficiency is demonstrated. With a semiconductor saturable absorber mirror for passive mode-locking and a Gires-Tournois interferometer mirror for intracavity dispersion compensation, stable mode-locking pulses of 297 fs duration at 1042 nm were obtained. The maximum average power of 3.07 W was realized under 5.17 W absorbed pump power, corresponding to as high as 59.4% opt-opt efficiency. The single pulse energy and peak power are about 35.5 nJ and 119.5 kW, respectively.

Advanced High-Temperature Engine Materials Technology Progresses

NASA Technical Reports Server (NTRS)

1995-01-01

The objective of the Advanced High Temperature Engine Materials Technology Program (HITEMP) is to generate technology for advanced materials and structural analysis that will increase fuel economy, improve reliability, extend life, and reduce operating costs for 21st century civil propulsion systems. The primary focus is on fan and compressor materials (polymer-matrix composites--PMC's), compressor and turbine materials (superalloys, and metal-matrix and intermetallic-matrix composites--MMC's and IMC's) and turbine materials (ceramic-matrix composites--CMC's). These advanced materials are being developed by in-house researchers and on grants and contracts. NASA considers this program to be a focused materials and structures research effort that builds on our base research programs and supports component-development projects. HITEMP is coordinated with the Advanced Subsonic Technology (AST) Program and the Department of Defense/NASA Integrated High-Performance Turbine Engine Technology (IHPTET) Program. Advanced materials and structures technologies from HITEMP may be used in these future applications. Recent technical accomplishments have not only improved the state-of-the-art but have wideranging applications to industry. A high-temperature thin-film strain gage was developed to measure both dynamic and static strain up to 1100 C (2000 F). The gage's unique feature is that it is minimally intrusive. This technology, which received a 1995 R&D 100 Award, has been transferred to AlliedSignal Engines, General Electric Company, and Ford Motor Company. Analytical models developed at the NASA Lewis Research Center were used to study Textron Specialty Materials' manufacturing process for titanium-matrix composite rings. Implementation of our recommendations on tooling and processing conditions resulted in the production of defect free rings. In the Lincoln Composites/AlliedSignal/Lewis cooperative program, a composite compressor case is being manufactured with a Lewis

High efficiency III-nitride light-emitting diodes

DOEpatents

Crawford, Mary; Koleske, Daniel; Cho, Jaehee; Zhu, Di; Noemaun, Ahmed; Schubert, Martin F; Schubert, E. Fred

2013-05-28

Tailored doping of barrier layers enables balancing of the radiative recombination among the multiple-quantum-wells in III-Nitride light-emitting diodes. This tailored doping enables more symmetric carrier transport and uniform carrier distribution which help to reduce electron leakage and thus reduce the efficiency droop in high-power III-Nitride LEDs. Mitigation of the efficiency droop in III-Nitride LEDs may enable the pervasive market penetration of solid-state-lighting technologies in high-power lighting and illumination.

Overview of the Advanced High Frequency Branch

NASA Technical Reports Server (NTRS)

Miranda, Felix A.

2015-01-01

This presentation provides an overview of the competencies, selected areas of research and technology development activities, and current external collaborative efforts of the NASA Glenn Research Center's Advanced High Frequency Branch.

High-speed civil transport - Advanced flight deck challenges

NASA Technical Reports Server (NTRS)

Swink, Jay R.; Goins, Richard T.

1992-01-01

This paper presents the results of a nine month study of the HSCT flight deck challenges and assessment of its benefits. Operational requirements are discussed and the most significant findings for specified advanced concepts are highlighted. These concepts are a no nose-droop configuration, a far forward cockpit location and advanced crew monitoring and control of complex systems. Results indicate that the no nose-droop configuration is critically dependent on the design and development of a safe, reliable and certifiable synthetic vision system (SVS). This configuration would cause significant weight, performance and cost penalties. A far forward cockpit configuration with a tandem seating arrangement allows either an increase in additional payload or potential downsizing of the vehicle leading to increased performance efficiency and reductions in emissions. The technologies enabling such capabilities, which provide for Category III all-weather opreations on every flight represent a benefit multiplier in a 20005 ATM network in terms of enhanced economic viability and environmental acceptability.

Advanced Metal-Hydrides-Based Thermal Battery: A New Generation of High Density Thermal Battery Based on Advanced Metal Hydrides

DOE Office of Scientific and Technical Information (OSTI.GOV)

None

HEATS Project: The University of Utah is developing a compact hot-and-cold thermal battery using advanced metal hydrides that could offer efficient climate control system for EVs. The team’s innovative designs of heating and cooling systems for EVs with high energy density, low-cost thermal batteries could significantly reduce the weight and eliminate the space constraint in automobiles. The thermal battery can be charged by plugging it into an electrical outlet while charging the electric battery and it produces heat and cold through a heat exchanger when discharging. The ultimate goal of the project is a climate-controlling thermal battery that can lastmore » up to 5,000 charge and discharge cycles while substantially increasing the driving range of EVs, thus reducing the drain on electric batteries.« less

Thermophotonics for ultra-high efficiency visible LEDs

NASA Astrophysics Data System (ADS)

Ram, Rajeev J.

2017-02-01

The wall-plug efficiency of modern light-emitting diodes (LEDs) has far surpassed all other forms of lighting and is expected to improve further as the lifetime cost of a luminaire is today dominated by the cost of energy. The drive towards higher efficiency inevitably opens the question about the limits of future enhancement. Here, we investigate thermoelectric pumping as a means for improving efficiency in wide-bandgap GaN based LEDs. A forward biased diode can work as a heat pump, which pumps lattice heat into the electrons injected into the active region via the Peltier effect. We experimentally demonstrate a thermally enhanced 450 nm GaN LED, in which nearly fourfold light output power is achieved at 615 K (compared to 295 K room temperature operation), with virtually no reduction in the wall-plug efficiency at bias V < ℏω/q. This result suggests the possibility of removing bulky heat sinks in high power LED products. A review of recent high-efficiency GaN LEDs suggests that Peltier thermal pumping plays a more important role in a wide range of modern LED structures that previously thought - opening a path to even higher efficiencies and lower lifetime costs for future lighting.

Development and Characterization of High-Efficiency, High-Specific Impulse Xenon Hall Thrusters

NASA Technical Reports Server (NTRS)

Hofer, Richard R.; Jacobson, David (Technical Monitor)

2004-01-01

This dissertation presents research aimed at extending the efficient operation of 1600 s specific impulse Hall thruster technology to the 2000 to 3000 s range. Motivated by previous industry efforts and mission studies, the aim of this research was to develop and characterize xenon Hall thrusters capable of both high-specific impulse and high-efficiency operation. During the development phase, the laboratory-model NASA 173M Hall thrusters were designed and their performance and plasma characteristics were evaluated. Experiments with the NASA-173M version 1 (v1) validated the plasma lens magnetic field design. Experiments with the NASA 173M version 2 (v2) showed there was a minimum current density and optimum magnetic field topography at which efficiency monotonically increased with voltage. Comparison of the thrusters showed that efficiency can be optimized for specific impulse by varying the plasma lens. During the characterization phase, additional plasma properties of the NASA 173Mv2 were measured and a performance model was derived. Results from the model and experimental data showed how efficient operation at high-specific impulse was enabled through regulation of the electron current with the magnetic field. The electron Hall parameter was approximately constant with voltage, which confirmed efficient operation can be realized only over a limited range of Hall parameters.

Advancements in high-power high-brightness laser bars and single emitters for pumping and direct diode application

NASA Astrophysics Data System (ADS)

An, Haiyan; Jiang, Ching-Long J.; Xiong, Yihan; Zhang, Qiang; Inyang, Aloysius; Felder, Jason; Lewin, Alexander; Roff, Robert; Heinemann, Stefan; Schmidt, Berthold; Treusch, Georg

2015-03-01

We have continuously optimized high fill factor bar and packaging design to increase power and efficiency for thin disc laser system pump application. On the other hand, low fill factor bars packaged on the same direct copper bonded (DCB) cooling platform are used to build multi-kilowatt direct diode laser systems. We have also optimized the single emitter designs for fiber laser pump applications. In this paper, we will give an overview of our recent advances in high power high brightness laser bars and single emitters for pumping and direct diode application. We will present 300W bar development results for our next generation thin disk laser pump source. We will also show recent improvements on slow axis beam quality of low fill factor bar and its application on performance improvement of 4-5 kW TruDiode laser system with BPP of 30 mm*mrad from a 600 μm fiber. Performance and reliability results of single emitter for multiemitter fiber laser pump source will be presented as well.

Highly efficient solid state magnetoelectric gyrators

NASA Astrophysics Data System (ADS)

Leung, Chung Ming; Zhuang, Xin; Friedrichs, Daniel; Li, Jiefang; Erickson, Robert W.; Laletin, V.; Popov, M.; Srinivasan, G.; Viehland, D.

2017-09-01

An enhancement in the power-conversion-efficiency (η) of a magneto-electric (ME) gyrator has been found by the use of Mn-substituted nickel zinc ferrite. A trilayer gyrator of Mn-doped Ni0.8Zn0.2Fe2O3 and Pb(Zr,Ti)O3 has η = 85% at low power conditions (˜20 mW/in3) and η ≥ 80% at high power conditions (˜5 W/in3). It works close to fundamental electromechanical resonance in both direct and converse modes. The value of η is by far the highest reported so far, which is due to the high mechanical quality factor (Qm) of the magnetostrictive ferrite. Such highly efficient ME gyrators with a significant power density could become important elements in power electronics, potentially replacing electromagnetic and piezoelectric transformers.

Evaluation of High-Power Solar Electric Propulsion using Advanced Ion, Hall, MPD, and PIT Thrusters for Lunar and Mars Cargo Missions

NASA Technical Reports Server (NTRS)

Frisbee, Robert H.

2006-01-01

This paper presents the results of mission analyses that expose the advantages and disadvantages of high-power (MWe-class) Solar Electric Propulsion (SEP) for Lunar and Mars Cargo missions that would support human exploration of the Moon and Mars. In these analyses, we consider SEP systems using advanced Ion thrusters (the Xenon [Xe] propellant Herakles), Hall thrusters (the Bismuth [Bi] propellant Very High Isp Thruster with Anode Layer [VHITAL], magnetoplasmadynamic (MPD) thrusters (the Lithium [Li] propellant Advanced Lithium-Fed, Applied-field Lorentz Force Accelerator (ALFA2), and pulsed inductive thruster (PIT) (the Ammonia [NH3] propellant Nuclear-PIT [NuPIT]). The analyses include comparison of the advanced-technology propulsion systems (VHITAL, ALFA2, and NuPIT) relative to state-of-theart Ion (Herakles) propulsion systems and quantify the unique benefits of the various technology options such as high power-per-thruster (and/or high power-per-thruster packaging volume), high specific impulse (Isp), high-efficiency, and tankage mass (e.g., low tankage mass due to the high density of bismuth propellant). This work is based on similar analyses for Nuclear Electric Propulsion (NEP) systems.

Highly efficient fully transparent inverted OLEDs

NASA Astrophysics Data System (ADS)

Meyer, J.; Winkler, T.; Hamwi, S.; Schmale, S.; Kröger, M.; Görrn, P.; Johannes, H.-H.; Riedl, T.; Lang, E.; Becker, D.; Dobbertin, T.; Kowalsky, W.

2007-09-01

One of the unique selling propositions of OLEDs is their potential to realize highly transparent devices over the visible spectrum. This is because organic semiconductors provide a large Stokes-Shift and low intrinsic absorption losses. Hence, new areas of applications for displays and ambient lighting become accessible, for instance, the integration of OLEDs into the windshield or the ceiling of automobiles. The main challenge in the realization of fully transparent devices is the deposition of the top electrode. ITO is commonly used as transparent bottom anode in a conventional OLED. To obtain uniform light emission over the entire viewing angle and a low series resistance, a TCO such as ITO is desirable as top contact as well. However, sputter deposition of ITO on top of organic layers causes damage induced by high energetic particles and UV radiation. We have found an efficient process to protect the organic layers against the ITO rf magnetron deposition process of ITO for an inverted OLED (IOLED). The inverted structure allows the integration of OLEDs in more powerful n-channel transistors used in active matrix backplanes. Employing the green electrophosphorescent material Ir(ppy) 3 lead to IOLED with a current efficiency of 50 cd/A and power efficiency of 24 lm/W at 100 cd/m2. The average transmittance exceeds 80 % in the visible region. The on-set voltage for light emission is lower than 3 V. In addition, by vertical stacking we achieved a very high current efficiency of more than 70 cd/A for transparent IOLED.

Noncovalent interaction-assisted drug delivery system with highly efficient uptake and release of paclitaxel for anticancer therapy.

PubMed

Wei, Yuping; Ma, Liang; Zhang, Liang; Xu, Xia

2017-01-01

An effective drug delivery system requires efficient drug uptake and release inside cancer cells. Here, we report a novel drug delivery system, in which paclitaxel (PTX) interacts with a novel cell penetrating peptide (CPP) through noncovalent interaction designed based on molecular simulations. This CPP/PTX complex confers high efficiency in delivering PTX into cancer cells not by endocytosis but by an energy-independent pathway. Once inside cells, the noncovalent interaction between PTX and the CPP may allow fast release of PTX within cells due to the direct translocation of CPP/PTX. This drug delivery system exhibits strong capacity for inhibition of tumor growth and offers a new avenue for the development of advanced drug delivery systems for anticancer therapy.

Advanced, Energy-Efficient Hybrid Membrane System for Industrial Water Reuse

DOE Office of Scientific and Technical Information (OSTI.GOV)

Toy, Lora; Choi, Young Chul; Hendren, Zachary

In the U.S. manufacturing sector, current industrial water use practices are energy-intensive and utilize and discharge high volumes of waters, rendering them not sustainable especially in light of the growing scarcity of suitable water supplies. To help address this problem, the goal of this project was to develop an advanced, cost-effective, hybrid membrane-based water treatment system that can improve the energy efficiency of industrial wastewater treatment while allowing at least 50% water reuse efficiency. This hybrid process would combine emerging Forward Osmosis (FO) and Membrane Distillation (MD) technology components into an integrated FO-MD system that can beneficially utilize low-grade wastemore » heat (i.e., T < 450 °F) in industrial facilities to produce distilled-quality product water for reuse. In this project, laboratory-, bench-, and pilot-scale experiments on the hybrid FO-MD system were conducted for industrial wastewater treatment. It was demonstrated at laboratory, bench, and pilot scales that FO-MD membrane technology can concentrate brine to very high total dissolved solids (TDS) levels (>200,000 ppm) that are at least 2.5 times higher than the TDS level to which RO can achieve. In laboratory testing, currently available FO and MD membranes were tested to select for high-performing membranes with high salt rejection and high water flux. Multiple FO membrane/draw-salt solution combinations that gave high water flux with higher than 98% salt rejection were also identified. Reverse draw-salt fluxes were observed to be much lower for divalent salts than for monovalent salts. MD membranes were identified that had 99.9+% salt rejection and water flux as high as 50-90 L/(m 2·h) for flat-sheet membranes and >20 L/(m 2·h) for hollow fibers. In bench-scale testing, a single unit of commercially available FO and MD membrane modules were evaluated for continuous, integrated operation. Using the laboratory- and bench-scale test data, numerical

High Efficiency Electron-Laser Interactions in Tapered Helical Undulators

NASA Astrophysics Data System (ADS)

Duris, Joseph Patrick

Efficient coupling of relativistic electron beams with high power radiation lies at the heart of advanced accelerator and light source research and development. The inverse free electron laser is a stable accelerator capable of harnessing very high intensity laser electric fields to efficiently transfer large powers from lasers to electron beams. In this dissertation, we first present the theoretical framework to describe the interaction, and then apply our improved understanding of the IFEL to the design and numerical study of meter-long, GeV IFELs for compact light sources. The central experimental work of the dissertation is the UCLA BNL helical inverse free electron laser experiment at the Accelerator Test Facility in Brookhaven National Laboratory which used a strongly tapered 54cm long, helical, permanent magnet undulator and a several hundred GW CO2 laser to accelerate electrons from 52 to 106MeV, setting new records for inverse free electron laser energy gain (54MeV) and average accelerating gradient (100MeV/m). The undulator design and fabrication as well as experimental diagnostics are presented. In order to improve the stability and quality of the accelerated electron beam, we redesigned the undulator for a slightly reduced output energy by modifying the magnet gap throughout the undulator, and we used this modified undulator to demonstrated capture of >25% of the injected beam without prebunching. In the study of heavily loaded GeV inverse free electron lasers, we show that a majority of the power may be transferred from a laser to the accelerated electron beam. Reversing the process to decelerate high power electron beams, a mechanism we refer to as tapering enhanced stimulated superradiant amplification, offers a clear path to high power light sources. We present studies of radiation production for a wide range of wavelengths (10mum, 13nm, and 0.3nm) using this method and discuss the design for a deceleration experiment using the same undulator used

Silicon-based highly-efficient fiber-to-waveguide coupler for high index contrast systems

NASA Astrophysics Data System (ADS)

Nguyen, Victor; Montalbo, Trisha; Manolatou, Christina; Agarwal, Anu; Hong, Ching-yin; Yasaitis, John; Kimerling, L. C.; Michel, Jurgen

2006-02-01

A coupler to efficiently transfer broadband light from a single-mode optical fiber to a single-mode high-index contrast waveguide has been fabricated on a silicon substrate. We utilized a novel coupling scheme, with a vertically asymmetric design consisting of a stepwise parabolic graded index profile combined with a horizontal taper, to simultaneously confine light in both directions. Coupling efficiency has been measured as a function of the device dimensions. The optimal coupling efficiency is achieved for structures whose length equals the focal distance of the graded index and whose input width is close to the mode field diameter of the fiber. The fabricated structure is compact, robust and highly efficient, with an insertion loss of 2.2dB at 1550nm. The coupler exhibits less than 1dB variation in coupling efficiency in the measured spectral range from 1520nmto1620nm. The lowest insertion loss of 1.9dB is measured at 1540nm. The coupler design offers highly efficient coupling for single mode waveguides of core indices up to 2.2.

Advanced general aviation engine/airframe integration study

NASA Technical Reports Server (NTRS)

Zmroczek, L. A.

1982-01-01

A comparison of the in-airframe performance and efficiency of the advanced engine concepts is presented. The results indicate that the proposed advanced engines can significantly improve the performance and economy of general aviation airplanes. The engine found to be most promising is the highly advanced version of a rotary combustion (Wankel) engine. The low weight and fuel consumption of this engine, as well as its small size, make it suited for aircraft use.

Efficient, high-power, and radially polarized fiber laser

PubMed Central

Lin, Di; Xia, Kegui; Li, Jianlang; Li, Ruxin; Ueda, Ken-ichi; Li, Guoqiang; Li, Xiaojun

2017-01-01

We demonstrate an ytterbium-doped fiber laser that emits high-power radially polarized light efficiently. In this study, a photonic crystal grating (PCG) was used as a polarization-selective output coupler, and the power of the radially polarized laser reached 2.42 W with a slope efficiency of 45.9% and a polarization purity of 96%. The results reveal that the inclusion of the PCG mirror into the fiber laser are particularly promising for generating high-power radially polarized light efficiently in view of its many important applications. PMID:20596223

Highly efficient white OLEDs for lighting applications

NASA Astrophysics Data System (ADS)

Murano, Sven; Burghart, Markus; Birnstock, Jan; Wellmann, Philipp; Vehse, Martin; Werner, Ansgar; Canzler, Tobias; Stübinger, Thomas; He, Gufeng; Pfeiffer, Martin; Boerner, Herbert

2005-10-01

The use of organic light-emitting diodes (OLEDs) for large area general lighting purposes is gaining increasing interest during the recent years. Especially small molecule based OLEDs have already shown their potential for future applications. For white light emission OLEDs, power efficiencies exceeding that of incandescent bulbs could already be demonstrated, however additional improvements are needed to further mature the technology allowing for commercial applications as general purpose illuminating sources. Ultimately the efficiencies of fluorescent tubes should be reached or even excelled, a goal which could already be achieved in the past for green OLEDs.1 In this publication the authors will present highly efficient white OLEDs based on an intentional doping of the charge carrier transport layers and the usage of different state of the art emission principles. This presentation will compare white PIN-OLEDs based on phosphorescent emitters, fluorescent emitters and stacked OLEDs. It will be demonstrated that the reduction of the operating voltage by the use of intentionally doped transport layers leads to very high power efficiencies for white OLEDs, demonstrating power efficiencies of well above 20 lm/W @ 1000 cd/m2. The color rendering properties of the emitted light is very high and CRIs between 85 and 95 are achieved, therefore the requirements for standard applications in the field of lighting applications could be clearly fulfilled. The color coordinates of the light emission can be tuned within a wide range through the implementation of minor structural changes.

High Efficiency Carbon Nanotube Thread Antennas

NASA Astrophysics Data System (ADS)

Bengio, Elie; Senic, Damir; Taylor, Lauren; Tsentalovich, Dmitri; Chen, Peiyu; Holloway, Christopher; Novotny, David; Babakhani, Aydin; Long, Christopher; Booth, James; Orloff, Nathan; Pasquali, Matteo

Although previous research has explored the underlying theory of high-frequency behavior of carbon nanotubes (CNTs) and CNT bundles for antennas, there is a gap in the literature for direct experimental measurements of radiation efficiency. Here we report a novel measurement technique to accurately characterize the radiation efficiency of quarter-wavelength monopole antennas made from CNT thread. At medical device (1 GHz) and Wi-Fi (2.4 GHz) frequencies, we measured the highest absolute values of radiation efficiency in the literature for CNT antennas, matching that of copper wire. We also report the first direct experimental observation that, contrary to metals, the radiation efficiency of the CNT thread improves significantly at higher frequencies. These results pave the way for practical applications of CNT thread antennas, particularly in the aerospace and wearable electronics industries where weight saving is a priority.

High efficiency tantalum-based ceramic composite structures

NASA Technical Reports Server (NTRS)

Stewart, David A. (Inventor); Leiser, Daniel B. (Inventor); DiFiore, Robert R. (Inventor); Katvala, Victor W. (Inventor)

2010-01-01

Tantalum-based ceramics are suitable for use in thermal protection systems. These composite structures have high efficiency surfaces (low catalytic efficiency and high emittance), thereby reducing heat flux to a spacecraft during planetary re-entry. These ceramics contain tantalum disilicide, molybdenum disilicide and borosilicate glass. The components are milled, along with a processing aid, then applied to a surface of a porous substrate, such as a fibrous silica or carbon substrate. Following application, the coating is then sintered on the substrate. The composite structure is substantially impervious to hot gas penetration and capable of surviving high heat fluxes at temperatures approaching 3000.degree. F. and above.

Advanced Electrical Materials and Components Being Developed

NASA Technical Reports Server (NTRS)

Schwarze, Gene E.

2004-01-01

All aerospace systems require power management and distribution (PMAD) between the energy and power source and the loads. The PMAD subsystem can be broadly described as the conditioning and control of unregulated power from the energy source and its transmission to a power bus for distribution to the intended loads. All power and control circuits for PMAD require electrical components for switching, energy storage, voltage-to-current transformation, filtering, regulation, protection, and isolation. Advanced electrical materials and component development technology is a key technology to increasing the power density, efficiency, reliability, and operating temperature of the PMAD. The primary means to develop advanced electrical components is to develop new and/or significantly improved electronic materials for capacitors, magnetic components, and semiconductor switches and diodes. The next important step is to develop the processing techniques to fabricate electrical and electronic components that exceed the specifications of presently available state-of-the-art components. The NASA Glenn Research Center's advanced electrical materials and component development technology task is focused on the following three areas: 1) New and/or improved dielectric materials for the development of power capacitors with increased capacitance volumetric efficiency, energy density, and operating temperature; 2) New and/or improved high-frequency, high-temperature soft magnetic materials for the development of transformers and inductors with increased power density, energy density, electrical efficiency, and operating temperature; 3) Packaged high-temperature, high-power density, high-voltage, and low-loss SiC diodes and switches.

NREL’s Advanced Analytics Research for Energy-Efficient Buildings

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kutscher, Chuck; Livingood, Bill; Wilson, Eric

At NREL, we believe in building better buildings. More importantly, high-performance buildings that can do more and be smarter than ever before. Forty percent of the total energy consumption in the United States comes from buildings. Working together, we can dramatically shrink that number. But first, it starts with the research: our observations, experiments, modeling, analysis, and more. NREL’s advanced analytics research has already proven to reduce energy use, save money, and stabilize the grid.

High efficiency magnetic bearings

NASA Technical Reports Server (NTRS)

Studer, Philip A.; Jayaraman, Chaitanya P.; Anand, Davinder K.; Kirk, James A.

1993-01-01

Research activities concerning high efficiency permanent magnet plus electromagnet (PM/EM) pancake magnetic bearings at the University of Maryland are reported. A description of the construction and working of the magnetic bearing is provided. Next, parameters needed to describe the bearing are explained. Then, methods developed for the design and testing of magnetic bearings are summarized. Finally, a new magnetic bearing which allows active torque control in the off axes directions is discussed.

Raytheon Advanced Miniature Cryocooler Characterization Testing

NASA Astrophysics Data System (ADS)

Conrad, T.; Yates, R.; Schaefer, B.; Bellis, L.; Pillar, M.; Barr, M.

2015-12-01

The Raytheon Advanced Miniature (RAM) cryocooler is a flight packaged, high frequency pulse tube cooler with an integrated surge volume and inertance tube. Its design has been fully optimized to make use of the Raytheon Advanced Regenerator, resulting in improved efficiency relative to previous Raytheon pulse tube coolers. In this paper, thermodynamic characterization data for the RAM cryocooler is presented along with details of its design specifications.

High Efficiency, Low Emissions Homogeneous Charge Compression Ignition (HCCI) Engines

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gravel, Roland; Maronde, Carl; Gehrke, Chris

2010-10-30

This is the final report of the High Efficiency Clean Combustion (HECC) Research Program for the U.S. Department of Energy. Work under this co-funded program began in August 2005 and finished in July 2010. The objective of this program was to develop and demonstrate a low emission, high thermal efficiency engine system that met 2010 EPA heavy-duty on-highway truck emissions requirements (0.2g/bhp-hr NOx, 0.14g/bhp-hr HC and 0.01g/bhp-hr PM) with a thermal efficiency of 46%. To achieve this goal, development of diesel homogenous charge compression ignition (HCCI) combustion was the chosen approach. This report summarizes the development of diesel HCCI combustionmore » and associated enabling technologies that occurred during the HECC program between August 2005 and July 2010. This program showed that although diesel HCCI with conventional US diesel fuel was not a feasible means to achieve the program objectives, the HCCI load range could be increased with a higher volatility, lower cetane number fuel, such as gasoline, if the combustion rate could be moderated to avoid excessive cylinder pressure rise rates. Given the potential efficiency and emissions benefits, continued research of combustion with low cetane number fuels and the effects of fuel distillation are recommended. The operation of diesel HCCI was only feasible at part-load due to a limited fuel injection window. A 4% fuel consumption benefit versus conventional, low-temperature combustion was realized over the achievable operating range. Several enabling technologies were developed under this program that also benefited non-HCCI combustion. The development of a 300MPa fuel injector enabled the development of extended lifted flame combustion. A design methodology for minimizing the heat transfer to jacket water, known as precision cooling, will benefit conventional combustion engines, as well as HCCI engines. An advanced combustion control system based on cylinder pressure measurements was developed. A

Concepts for high efficient white OLEDs for lighting applications

NASA Astrophysics Data System (ADS)

Hunze, A.; Krause, R.; Seidel, S.; Weiss, O.; Kozlowski, F.; Schmid, G.; Meyer, J.; Kröger, M.; Johannes, H. H.; Kowalsky, W.; Dobbertin, T.

2007-09-01

Apart from usage of organic light emitting diodes for flat panel display applications OLEDs are a potential candidate for the next solid state lighting technology. One key parameter is the development of high efficient, stable white devices. To realize this goal there are different concepts. Especially by using highly efficient phosphorescent guest molecules doped into a suitable host material high efficiency values can be obtained. We started our investigations with a single dopant and extended this to a two phosphorescent emitter approach leading to a device with a high power efficiency of more than 25 lm/W @ 1000 cd/m2. The disadvantage of full phosphorescent device setups is that esp. blue phosphorescent emitters show an insufficient long-term stability. A possibility to overcome this problem is the usage of more stable fluorescent blue dopants, whereas, due to the fact that only singlet excitons can decay radiatively, the efficiency is lower. With a concept, proposed by Sun et al.1 in 2006, it is possible to manage the recombination zone and thus the contribution from the different dopants. With this approach stable white color coordinates with sufficient current efficiency values have been achieved.

Recent advances in quantitative high throughput and high content data analysis.

PubMed

Moutsatsos, Ioannis K; Parker, Christian N

2016-01-01

High throughput screening has become a basic technique with which to explore biological systems. Advances in technology, including increased screening capacity, as well as methods that generate multiparametric readouts, are driving the need for improvements in the analysis of data sets derived from such screens. This article covers the recent advances in the analysis of high throughput screening data sets from arrayed samples, as well as the recent advances in the analysis of cell-by-cell data sets derived from image or flow cytometry application. Screening multiple genomic reagents targeting any given gene creates additional challenges and so methods that prioritize individual gene targets have been developed. The article reviews many of the open source data analysis methods that are now available and which are helping to define a consensus on the best practices to use when analyzing screening data. As data sets become larger, and more complex, the need for easily accessible data analysis tools will continue to grow. The presentation of such complex data sets, to facilitate quality control monitoring and interpretation of the results will require the development of novel visualizations. In addition, advanced statistical and machine learning algorithms that can help identify patterns, correlations and the best features in massive data sets will be required. The ease of use for these tools will be important, as they will need to be used iteratively by laboratory scientists to improve the outcomes of complex analyses.

Phase III Advanced Anodes and Cathodes Utilized in Energy Efficient Aluminum Production Cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

R.A. Christini; R.K. Dawless; S.P. Ray

2001-11-05

During Phase I of the present program, Alcoa developed a commercial cell concept that has been estimated to save 30% of the energy required for aluminum smelting. Phase ii involved the construction of a pilot facility and operation of two pilots. Phase iii of the Advanced Anodes and Cathodes Program was aimed at bench experiments to permit the resolution of certain questions to be followed by three pilot cells. All of the milestones related to materials, in particular metal purity, were attained with distinct improvements over work in previous phases of the program. NiO additions to the ceramic phase andmore » Ag additions to the Cu metal phase of the cermet improved corrosion resistance sufficiently that the bench scale pencil anodes met the purity milestones. Some excellent metal purity results have been obtained with anodes of the following composition: Further improvements in anode material composition appear to be dependent on a better understanding of oxide solubilities in molten cryolite. For that reason, work was commissioned with an outside consultant to model the MeO - cryolite systems. That work has led to a better understanding of which oxides can be used to substitute into the NiO-Fe2O3 ceramic phase to stabilize the ferrites and reduce their solubility in molten cryolite. An extensive number of vertical plate bench electrolysis cells were run to try to find conditions where high current efficiencies could be attained. TiB2-G plates were very inconsistent and led to poor wetting and drainage. Pure TiB2 did produce good current efficiencies at small overlaps (shadowing) between the anodes and cathodes. This bench work with vertical plate anodes and cathodes reinforced the importance of good cathode wetting to attain high current efficiencies. Because of those conclusions, new wetting work was commissioned and became a major component of the research during the third year of Phase III. While significant progress was made in several areas, much work

High Performance Computing Modeling Advances Accelerator Science for High-Energy Physics

DOE PAGES

Amundson, James; Macridin, Alexandru; Spentzouris, Panagiotis

2014-07-28

The development and optimization of particle accelerators are essential for advancing our understanding of the properties of matter, energy, space, and time. Particle accelerators are complex devices whose behavior involves many physical effects on multiple scales. Therefore, advanced computational tools utilizing high-performance computing are essential for accurately modeling them. In the past decade, the US Department of Energy's SciDAC program has produced accelerator-modeling tools that have been employed to tackle some of the most difficult accelerator science problems. The authors discuss the Synergia framework and its applications to high-intensity particle accelerator physics. Synergia is an accelerator simulation package capable ofmore » handling the entire spectrum of beam dynamics simulations. Our authors present Synergia's design principles and its performance on HPC platforms.« less

Prediction and design of efficient exciplex emitters for high-efficiency, thermally activated delayed-fluorescence organic light-emitting diodes.

PubMed

Liu, Xiao-Ke; Chen, Zhan; Zheng, Cai-Jun; Liu, Chuan-Lin; Lee, Chun-Sing; Li, Fan; Ou, Xue-Mei; Zhang, Xiao-Hong

2015-04-08

High-efficiency, thermally activated delayed-fluorescence organic light-emitting diodes based on exciplex emitters are demonstrated. The best device, based on a TAPC:DPTPCz emitter, shows a high external quantum efficiency of 15.4%. Strategies for predicting and designing efficient exciplex emitters are also provided. This approach allow prediction and design of efficient exciplex emitters for achieving high-efficiency organic light-emitting diodes, for future use in displays and lighting applications. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Highly active and efficient catalysts for alkoxycarbonylation of alkenes

PubMed Central

Dong, Kaiwu; Fang, Xianjie; Gülak, Samet; Franke, Robert; Spannenberg, Anke; Neumann, Helfried; Jackstell, Ralf; Beller, Matthias

2017-01-01

Carbonylation reactions of alkenes constitute the most important industrial processes in homogeneous catalysis. Despite the tremendous progress in this transformation, the development of advanced catalyst systems to improve their activity and widen the range of feedstocks continues to be essential for new practical applications. Herein a palladium catalyst based on 1,2-bis((tert-butyl(pyridin-2-yl)phosphanyl)methyl)benzene L3 (pytbpx) is rationally designed and synthesized. Application of this system allows a general alkoxycarbonylation of sterically hindered and demanding olefins including all kinds of tetra-, tri- and 1,1-disubstituted alkenes as well as natural products and pharmaceuticals to the desired esters in excellent yield. Industrially relevant bulk ethylene is functionalized with high activity (TON: >1,425,000; TOF: 44,000 h−1 for initial 18 h) and selectivity (>99%). Given its generality and efficiency, we expect this catalytic system to immediately impact both the chemical industry and research laboratories by providing a practical synthetic tool for the transformation of nearly any alkene into a versatile ester product. PMID:28120947

Creation of High Efficient Firefly Luciferase

NASA Astrophysics Data System (ADS)

Nakatsu, Toru

Firefly emits visible yellow-green light. The bioluminescence reaction is carried out by the enzyme luciferase. The bioluminescence of luciferase is widely used as an excellent tool for monitoring gene expression, the measurement of the amount of ATP and in vivo imaging. Recently a study of the cancer metastasis is carried out by in vivo luminescence imaging system, because luminescence imaging is less toxic and more useful for long-term assay than fluorescence imaging by GFP. However the luminescence is much dimmer than fluorescence. Then bioluminescence imaging in living organisms demands the high efficient luciferase which emits near infrared lights or enhances the emission intensity. Here I introduce an idea for creating the high efficient luciferase based on the crystal structure.

High efficiency carbon nanotube thread antennas

NASA Astrophysics Data System (ADS)

Amram Bengio, E.; Senic, Damir; Taylor, Lauren W.; Tsentalovich, Dmitri E.; Chen, Peiyu; Holloway, Christopher L.; Babakhani, Aydin; Long, Christian J.; Novotny, David R.; Booth, James C.; Orloff, Nathan D.; Pasquali, Matteo

2017-10-01

Although previous research has explored the underlying theory of high-frequency behavior of carbon nanotubes (CNTs) and CNT bundles for antennas, there is a gap in the literature for direct experimental measurements of radiation efficiency. These measurements are crucial for any practical application of CNT materials in wireless communication. In this letter, we report a measurement technique to accurately characterize the radiation efficiency of λ/4 monopole antennas made from the CNT thread. We measure the highest absolute values of radiation efficiency for CNT antennas of any type, matching that of copper wire. To capture the weight savings, we propose a specific radiation efficiency metric and show that these CNT antennas exceed copper's performance by over an order of magnitude at 1 GHz and 2.4 GHz. We also report direct experimental observation that, contrary to metals, the radiation efficiency of the CNT thread improves significantly at higher frequencies. These results pave the way for practical applications of CNT thread antennas, particularly in the aerospace and wearable electronics industries where weight saving is a priority.

NREL Inks Technology Agreement for High Efficiency Multijunction Solar

Science.gov Websites

) multijunction solar cells. While high-efficiency multijunction solar cells are commonly used for space Devices is excited to now be commercializing IMM solar cells for high-performance space and UAV Cells | News | NREL Inks Technology Agreement for High Efficiency Multijunction Solar Cells

High Efficiency End-Pumped Ho:Tm:YLF Disk Amplifier

NASA Technical Reports Server (NTRS)

Yu, Jirong; Singh, Upendra N.; Petros, Mulugeta; Axenson, Theresa J.; Barnes, Norman P.

1999-01-01

Space based coherent lidar for global wind measurement requires an all solid state laser system with high energy, high efficiency and narrow linewidth that operates in the eye safe region. A Q-switched, diode pumped Ho:Tm:YLF 2 micrometer laser with output energy of as much as 125 mJ at 6 Hz with an optical-to-optical efficiency of 3% has been reported. Single frequency operation of the laser was achieved by injection seeding. The design of this laser is being incorporated into NASA's SPARCLE (SPAce Readiness Coherent Lidar Experiment) wind lidar mission. Laser output energy ranging from 500 mJ to 2 J is required for an operational space coherent lidar. We previously developed a high energy Ho:Tm:YLF master oscillator and side pumped power amplifier system and demonstrated a 600-mJ single frequency pulse at a repetition rate of 10 Hz. Although the output energy is high, the optical-to-optical efficiency is only about 2%. Designing a high energy, highly efficient, conductively cooled 2-micrometer laser remains a challenge. In this paper, the preliminary result of an end-pumped amplifier that has a potential to provide a factor 3 of improvement in the system efficiency is reported.

Advanced Radioisotope Power Systems Segmented Thermoelectric Research

NASA Technical Reports Server (NTRS)

Caillat, Thierry

2004-01-01

Flight times are long; - Need power systems with >15 years life. Mass is at an absolute premium; - Need power systems with high specific power and scalability. 3 orders of magnitude reduction in solar irradiance from Earth to Pluto. Nuclear power sources preferable. The Overall objective is to develop low mass, high efficiency, low-cost Advanced Radioisotope Power System with double the Specific Power and Efficiency over state-of-the-art Radioisotope Thermoelectric Generators (RTGs).

NASA Advanced Exploration Systems: Advancements in Life Support Systems

NASA Technical Reports Server (NTRS)

Shull, Sarah A.; Schneider, Walter F.

2016-01-01

The NASA Advanced Exploration Systems (AES) Life Support Systems (LSS) project strives to develop reliable, energy-efficient, and low-mass spacecraft systems to provide environmental control and life support systems (ECLSS) critical to enabling long duration human missions beyond low Earth orbit (LEO). Highly reliable, closed-loop life support systems are among the capabilities required for the longer duration human space exploration missions assessed by NASA’s Habitability Architecture Team.

Gear systems for advanced turboprops

NASA Technical Reports Server (NTRS)

Wagner, Douglas A.

1987-01-01

A new generation of transport aircraft will be powered by efficient, advanced turboprop propulsion systems. Systems that develop 5,000 to 15,000 horsepower have been studied. Reduction gearing for these advanced propulsion systems is discussed. Allison Gas Turbine Division's experience with the 5,000 horsepower reduction gearing for the T56 engine is reviewed and the impact of that experience on advanced gear systems is considered. The reliability needs for component design and development are also considered. Allison's experience and their research serve as a basis on which to characterize future gear systems that emphasize low cost and high reliability.

Energy efficiency indicators for high electric-load buildings

DOE Office of Scientific and Technical Information (OSTI.GOV)

Aebischer, Bernard; Balmer, Markus A.; Kinney, Satkartar

2003-06-01

Energy per unit of floor area is not an adequate indicator for energy efficiency in high electric-load buildings. For two activities, restaurants and computer centres, alternative indicators for energy efficiency are discussed.

Advanced Micro Grid Energy Management Coupled with Integrated Volt/VAR Control for Improved Energy Efficiency, Energy Security, and Power Quality at DoD Installations

DTIC Science & Technology

2016-10-28

assumptions. List of Assumptions: Price of electrical energy : $0.07/kWh flat rate for energy at the base Price of peak power: $15/MW peak power...EW-201147) Advanced Micro-Grid Energy Management Coupled with Integrated Volt/VAR Control for Improved Energy Efficiency, Energy Security, and...12-C-0002 5b. GRANT NUMBER Advanced Micro-Grid Energy Management Coupled with Integrated Volt/VAR Control for Improved Energy Efficiency, Energy

Bridging the Geoscientist Workforce Gap: Advanced High School Geoscience Programs

NASA Astrophysics Data System (ADS)

Schmidt, Richard William

The purpose of this participatory action research was to create a comprehensive evaluation of advanced geoscience education in Pennsylvania public high schools and to ascertain the possible impact of this trend on student perceptions and attitudes towards the geosciences as a legitimate academic subject and possible career option. The study builds on an earlier examination of student perceptions conducted at Northern Arizona University in 2008 and 2009 but shifts the focus to high school students, a demographic not explored before in this context. The study consisted of three phases each examining a different facet of the advanced geoscience education issue. Phase 1 examined 572 public high schools in 500 school districts across Pennsylvania and evaluated the health of the state's advanced geoscience education through the use of an online survey instrument where districts identified the nature of their geoscience programs (if any). Phase 2 targeted two groups of students at one suburban Philadelphia high school with an established advanced geoscience courses and compared the attitudes and perceptions of those who had been exposed to the curricula to a similar group of students who had not. Descriptive and statistically significant trends were then identified in order to assess the impact of an advanced geoscience education. Phase 3 of the study qualitatively explored the particular attitudes and perceptions of a random sampling of the advanced geoscience study group through the use of one-on-one interviews that looked for more in-depth patterns of priorities and values when students considered such topics as course enrollment, career selection and educational priorities. The results of the study revealed that advanced geoscience coursework was available to only 8% of the state's 548,000 students, a percentage significantly below that of the other typical K-12 science fields. It also exposed several statistically significant differences between the perceptions and

Flexible Superhydrophobic and Superoleophilic MoS2 Sponge for Highly Efficient Oil-Water Separation.

PubMed

Gao, Xiaojia; Wang, Xiufeng; Ouyang, Xiaoping; Wen, Cuie

2016-06-02

Removal of oils and organic solvents from water is an important global challenge for energy conservation and environmental protection. Advanced sorbent materials with excellent sorption capacity need to be developed. Here we report on a superhydrophobic and superoleophilic MoS2 nanosheet sponge (SMS) for highly efficient separation and absorption of oils or organic solvents from water. This novel sponge exhibits excellent absorption performance through a combination of superhydrophobicity, high porosity, robust stability in harsh conditions (including flame retardance and inertness to corrosive and different temperature environments) and excellent mechanical properties. The dip-coating strategy proposed for the fabrication of the SMS, which does not require a complicated process or sophisticated equipment, is very straightforward and easy to scale up. This finding shows promise for water remediation and oil recovery.

High efficiency solar photovoltaic power module concept

NASA Technical Reports Server (NTRS)

Bekey, I.

1978-01-01

The investigation of a preliminary concept for high efficiency solar power generation in space is presented. The concept was a synergistic combination of spectral splitting, tailored bandgap cells, high concentration ratios, and cool cell areas.

MIC-SVM: Designing A Highly Efficient Support Vector Machine For Advanced Modern Multi-Core and Many-Core Architectures

DOE Office of Scientific and Technical Information (OSTI.GOV)

You, Yang; Song, Shuaiwen; Fu, Haohuan

2014-08-16

Support Vector Machine (SVM) has been widely used in data-mining and Big Data applications as modern commercial databases start to attach an increasing importance to the analytic capabilities. In recent years, SVM was adapted to the field of High Performance Computing for power/performance prediction, auto-tuning, and runtime scheduling. However, even at the risk of losing prediction accuracy due to insufficient runtime information, researchers can only afford to apply offline model training to avoid significant runtime training overhead. To address the challenges above, we designed and implemented MICSVM, a highly efficient parallel SVM for x86 based multi-core and many core architectures,more » such as the Intel Ivy Bridge CPUs and Intel Xeon Phi coprocessor (MIC).« less

Flexible, highly efficient all-polymer solar cells

PubMed Central

Kim, Taesu; Kim, Jae-Han; Kang, Tae Eui; Lee, Changyeon; Kang, Hyunbum; Shin, Minkwan; Wang, Cheng; Ma, Biwu; Jeong, Unyong; Kim, Taek-Soo; Kim, Bumjoon J.

2015-01-01

All-polymer solar cells have shown great potential as flexible and portable power generators. These devices should offer good mechanical endurance with high power-conversion efficiency for viability in commercial applications. In this work, we develop highly efficient and mechanically robust all-polymer solar cells that are based on the PBDTTTPD polymer donor and the P(NDI2HD-T) polymer acceptor. These systems exhibit high power-conversion efficiency of 6.64%. Also, the proposed all-polymer solar cells have even better performance than the control polymer-fullerene devices with phenyl-C61-butyric acid methyl ester (PCBM) as the electron acceptor (6.12%). More importantly, our all-polymer solar cells exhibit dramatically enhanced strength and flexibility compared with polymer/PCBM devices, with 60- and 470-fold improvements in elongation at break and toughness, respectively. The superior mechanical properties of all-polymer solar cells afford greater tolerance to severe deformations than conventional polymer-fullerene solar cells, making them much better candidates for applications in flexible and portable devices. PMID:26449658

Advances in High-Fidelity Multi-Physics Simulation Techniques

DTIC Science & Technology

2008-01-01

predictor - corrector method is used to advance the solution in time. 33 x (m) y (m ) 0 1 2 3.00001 0 1 2 3 4 5 40 x 50 Grid 3 Figure 17: Typical...Unclassified c . THIS PAGE Unclassified 17. LIMITATION OF ABSTRACT: SAR 18. NUMBER OF PAGES 60 Datta Gaitonde 19b. TELEPHONE...advanced parallel computing platforms. The motivation to develop high-fidelity algorithms derives from considerations in various areas of current

Pilot line report: Development of a high efficiency thin silicon solar cell

NASA Technical Reports Server (NTRS)

1978-01-01

Experimental technology advances were implemented to increase the conversion efficiency of ultrathin 2cm x 2cm cells, to demonstrate a capability for fabricating such cells at a rate of 10,000 per month, and to fabricate 200 large-area ultrathin cells to determine their feasibility of manufacture. A production rate of 10,000 50 micron m cells per month with lot average AM0 efficiencies of 11.5% was demonstrated, with peak efficiencies of 13.5% obtained. Losses in most stages of the processing were minimized, the remaining exceptions being in the photolithography and metallization steps for front contact generation and breakage handling. The 5cm x 5cm cells were fabricated with a peak yield in excess of 40% for over 10% AM0 efficiency. Greater fabrication volume is needed to fully evaluate the expected yield and efficiency levels for large cells.

Friction Stir Spot Welding of Advanced High Strength Steels

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hovanski, Yuri; Grant, Glenn J.; Santella, M. L.

Friction stir spot welding techniques were developed to successfully join several advanced high strength steels. Two distinct tool materials were evaluated to determine the effect of tool materials on the process parameters and joint properties. Welds were characterized primarily via lap shear, microhardness, and optical microscopy. Friction stir spot welds were compared to the resistance spot welds in similar strength alloys by using the AWS standard for resistance spot welding high strength steels. As further comparison, a primitive cost comparison between the two joining processes was developed, which included an evaluation of the future cost prospects of friction stir spotmore » welding in advanced high strength steels.« less

Advanced Technology Development for Stirling Convertors

NASA Technical Reports Server (NTRS)

Thieme, Lanny G.; Schreiber, Jeffrey G.

2004-01-01

A high-efficiency Stirling Radioisotope generator (SRG) for use on potential NASA space missions is being developed by the Department of Energy, Lockheed Martin, Stirling Technology Company, and NASA Glenn Research Center. GRC is also developing advanced technology for Stirling converters, aimed at substantially improving the specific power and efficiency of the converter.The status and results to date will be discussed in this paper.

Alternative Fuel and Advanced Technology Commercial Lawn Equipment (Spanish version); Clean Cities, Energy Efficiency & Renewable Energy (EERE) (in Spanish)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nelson, Erik

Powering commercial lawn equipment with alternative fuels or advanced engine technology is an effective way to reduce U.S. dependence on petroleum, reduce harmful emissions, and lessen the environmental impacts of commercial lawn mowing. Numerous alternative fuel and fuel-efficient advanced technology mowers are available. Owners turn to these mowers because they may save on fuel and maintenance costs, extend mower life, reduce fuel spillage and fuel theft, and demonstrate their commitment to sustainability.

Status and Progress of High-efficiency Silicon Solar Cells

NASA Astrophysics Data System (ADS)

Xiao, Shaoqing; Xu, Shuyan

High-efficiency Si solar cells have attracted more and more attention from researchers, scientists, engineers of photovoltaic (PV) industry for the past few decades. Many high-quality researchers and engineers in both academia and industry seek solutions to improve the cell efficiency and reduce the cost. This desire has stimulated a growing number of major research and research infrastructure programmes, and a rapidly increasing number of publications in this filed. This chapter reviews materials, devices and physics of high-efficiency Si solar cells developed over the last 20 years. In this chapter there is a fair number of topics, not only from the material viewpoint, introducing various materials that are required for high-efficiency Si solar cells, such as base materials (FZ-Si, CZ-Si, MCZ-Si and multi-Si), emitter materials (diffused emitter and deposited emitter), passivation materials (Al-back surface field, high-low junction, SiO2, SiO x , SiN x , Al2O3 and a-Si:H), and other functional materials (antireflective layer, TCO and metal electrode), but also from the device and physics point of view, elaborating on physics, cell concept, development and status of all kinds of high-efficiency Si solar cells, such as passivated emitter and rear contact (PERC), passivated emitter and rear locally diffused (PERL), passivated emitter and rear totally diffused (PERT), Pluto, interdigitated back-contacted (IBC), emitter-wrap-through (EWT), metallization-wrap-through (MWT), Heterojunction with intrinsic thin-layer (HIT) and so on. Some representative examples of high-efficiency Si solar cell materials and devices with excellent performance and competitive advantages are presented.

Thermal modeling of high efficiency AMTEC cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ivanenok, J.F. III; Sievers, R.K.; Crowley, C.J.

1995-12-31

Remotely condensed Alkali Metal Thermal to Electric Conversion (AMTEC) cells achieve high efficiency by thermally isolating the hot {beta} Alumina Solid Electrolyte (BASE) tube from the cold condensing region. In order to design high efficiency AMTEC cells the designer must understand the heat losses associated with the AMTEC process. The major parasitic heat losses are due to conduction and radiation, and significant coupling of the two mechanisms occurs. This paper describes an effort to characterize the thermal aspects of the model PL-6 AMTEC cell and apply this understanding to the design of a higher efficiency AMTEC cell, model PL-8. Twomore » parallel analyses were used to model the thermal characteristics of PL-6. The first was a lumped node model using the classical electric circuit analogy and the second was a detailed finite-difference model. The lumped node model provides high speed and reasonable accuracy, and the detailed finite-difference model provides a more accurate, as well as visual, description of the cell temperature profiles. The results of the two methods are compared to the as-measured PL-6 data. PL-6 was the first cell to use a micromachined condenser to lower the radiation losses to the condenser, and it achieved a conversion efficiency of 15% (3 W output/20 W Input) at a temperature of 1050 K.« less

High efficiency photoionization detector

DOEpatents

Anderson, David F.

1984-01-01

A high efficiency photoionization detector using tetraaminoethylenes in a gaseous state having a low ionization potential and a relative photoionization cross section which closely matches the emission spectrum of xenon gas. Imaging proportional counters are also disclosed using the novel photoionization detector of the invention. The compound of greatest interest is TMAE which comprises tetrakis(dimethylamino)ethylene which has a measured ionization potential of 5.36.+-.0.02 eV, and a vapor pressure of 0.35 torr at 20.degree. C.

A review of high-efficiency silicon solar cells

NASA Technical Reports Server (NTRS)

Rohatgi, A.

1986-01-01

Various parameters that affect solar cell efficiency were discussed. It is not understood why solar cells produced from less expensive Czochralski (Cz) silicon are less efficient than cells fabricated from more expensive float-zone (Fz) silicon. Performance characteristics were presented for recently produced, high-efficient solar cells fabricated by Westinghouse Electric Corp., Spire Corp., University of New South Wales, and Stanford University.

High probability neurotransmitter release sites represent an energy efficient design

PubMed Central

Lu, Zhongmin; Chouhan, Amit K.; Borycz, Jolanta A.; Lu, Zhiyuan; Rossano, Adam J; Brain, Keith L.; Zhou, You; Meinertzhagen, Ian A.; Macleod, Gregory T.

2016-01-01

Nerve terminals contain multiple sites specialized for the release of neurotransmitters. Release usually occurs with low probability, a design thought to confer many advantages. High probability release sites are not uncommon but their advantages are not well understood. Here we test the hypothesis that high probability release sites represent an energy efficient design. We examined release site probabilities and energy efficiency at the terminals of two glutamatergic motor neurons synapsing on the same muscle fiber in Drosophila larvae. Through electrophysiological and ultrastructural measurements we calculated release site probabilities to differ considerably between terminals (0.33 vs. 0.11). We estimated the energy required to release and recycle glutamate from the same measurements. The energy required to remove calcium and sodium ions subsequent to nerve excitation was estimated through microfluorimetric and morphological measurements. We calculated energy efficiency as the number of glutamate molecules released per ATP molecule hydrolyzed, and high probability release site terminals were found to be more efficient (0.13 vs. 0.06). Our analytical model indicates that energy efficiency is optimal (~0.15) at high release site probabilities (~0.76). As limitations in energy supply constrain neural function, high probability release sites might ameliorate such constraints by demanding less energy. Energy efficiency can be viewed as one aspect of nerve terminal function, in balance with others, because high efficiency terminals depress significantly during episodic bursts of activity. PMID:27593375

Materials-Enabled High-Efficiency (MEHE) Heavy-Duty Diesel Engines

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kass, M.; Veliz, M.

2011-09-30

The purpose of this Cooperative Research and Development Agreement (CRADA) between UTBattelle, Inc. and Caterpillar, Inc. was to improve diesel engine efficiency by incorporating advanced materials to enable higher combustion pressures and temperatures necessary for improved combustion. The project scope also included novel materials for use in advanced components and designs associated with waste-heat recovery and other concepts for improved thermal efficiency. Caterpillar initially provided ORNL with a 2004 Tier 2 C15 ACERT diesel engine (designed for on-highway use) and two 600 hp motoring dynamometers. The first year of the CRADA effort was focused on establishing a heavy-duty experimental enginemore » research cell. First year activities included procuring, installing and commissioning the cell infrastructure. Infrastructure components consisted of intake air handling system, water tower, exhaust handling system, and cell air conditioning. Other necessary infrastructure items included the fuel delivery system and bottled gas handling to support the analytical instrumentation. The second year of the CRADA focused on commissioning the dynamometer system to enable engine experimentation. In addition to the requirements associated with the dynamometer controller, the electrical system needed a power factor correction system to maintain continuity with the electrical grid. During the second year the engine was instrumented and baseline operated to confirm performance and commission the dynamometer. The engine performance was mapped and modeled according to requirements provided by Caterpillar. This activity was further supported by a Work-for-Others project from Caterpillar to evaluate a proprietary modeling system. A second Work-for-Others activity was performed to evaluate a novel turbocharger design. This project was highly successful and may lead to new turbocharger designs for Caterpillar heavy-duty diesel engines. During the third (and final) year of the

New high-efficiency silicon solar cells

NASA Technical Reports Server (NTRS)

Daud, T.; Crotty, G. T.

1985-01-01

A design for silicon solar cells was investigated as an approach to increasing the cell open-circuit voltage and efficiency for flat-plate terrestrial photovoltaic applications. This deviates from past designs, where either the entire front surface of the cell is covered by a planar junction or the surface is textured before junction formation, which results in an even greater (up to 70%) junction area. The heavily doped front region and the junction space charge region are potential areas of high recombination for generated and injected minority carriers. The design presented reduces junction area by spreading equidiameter dot junctions across the surface of the cell, spaced about a diffusion length or less from each other. Various dot diameters and spacings allowed variations in total junction area. A simplified analysis was done to obtain a first-order design optimization. Efficiencies of up to 19% can be obtained. Cell fabrication involved extra masking steps for selective junction diffusion, and made surface passivation a key element in obtaining good collection. It also involved photolithography, with line widths down to microns. A method is demonstrated for achieving potentially high open-circuit voltages and solar-cell efficiencies.

Metal–Dielectric Waveguides for High Efficiency Fluorescence Imaging

PubMed Central

Zhu, Liangfu; Zhang, Douguo; Wang, Ruxue; Wang, Pei; Ming, Hai; Badugu, Ramachandram; Du, Luping; Yuan, Xiaocong; Lakowicz, Joseph R.

2015-01-01

We demonstrate that Metal–Dielectric Waveguide structures (MDWs) with high efficiency of fluorescence coupling can be suitable as substrates for fluorescence imaging. This hybrid MDWs consists of a continuous metal film and a dielectric top layer. The optical modes sustaining inside this structure can be excited with a high numerical aperture (N.A) objective, and then focused into a virtual optical probe with high intensity, leading to efficient excitation of fluorophores deposited on top of the MDWs. The emitted fluorophores couple with the optical modes thus enabling the directional emission, which is verified by the back focal plane (BFP) imaging. These unique properties of MDWs have been adopted in a scanning laser confocal optical microscopy, and show the merit of high efficiency fluorescence imaging. MDWs can be easily fabricated by vapor deposition and/or spin coating, the silica surface of the MDWs is suitable for biomolecule tethering, and will offer new opportunities for cell biology and biophysics research. PMID:26525494

High-throughput screening with nanoimprinting 3D culture for efficient drug development by mimicking the tumor environment.

PubMed

Yoshii, Yukie; Furukawa, Takako; Waki, Atsuo; Okuyama, Hiroaki; Inoue, Masahiro; Itoh, Manabu; Zhang, Ming-Rong; Wakizaka, Hidekatsu; Sogawa, Chizuru; Kiyono, Yasushi; Yoshii, Hiroshi; Fujibayashi, Yasuhisa; Saga, Tsuneo

2015-05-01

Anti-cancer drug development typically utilizes high-throughput screening with two-dimensional (2D) cell culture. However, 2D culture induces cellular characteristics different from tumors in vivo, resulting in inefficient drug development. Here, we report an innovative high-throughput screening system using nanoimprinting 3D culture to simulate in vivo conditions, thereby facilitating efficient drug development. We demonstrated that cell line-based nanoimprinting 3D screening can more efficiently select drugs that effectively inhibit cancer growth in vivo as compared to 2D culture. Metabolic responses after treatment were assessed using positron emission tomography (PET) probes, and revealed similar characteristics between the 3D spheroids and in vivo tumors. Further, we developed an advanced method to adopt cancer cells from patient tumor tissues for high-throughput drug screening with nanoimprinting 3D culture, which we termed Cancer tissue-Originated Uniformed Spheroid Assay (COUSA). This system identified drugs that were effective in xenografts of the original patient tumors. Nanoimprinting 3D spheroids showed low permeability and formation of hypoxic regions inside, similar to in vivo tumors. Collectively, the nanoimprinting 3D culture provides easy-handling high-throughput drug screening system, which allows for efficient drug development by mimicking the tumor environment. The COUSA system could be a useful platform for drug development with patient cancer cells. Copyright © 2015 Elsevier Ltd. All rights reserved.

Wide-Band, High-Quantum-Efficiency Photodetector

NASA Technical Reports Server (NTRS)

Jackson, Deborah; Wilson, Daniel; Stern, Jeffrey

2007-01-01

A design has been proposed for a photodetector that would exhibit a high quantum efficiency (as much as 90 percent) over a wide wavelength band, which would typically be centered at a wavelength of 1.55 m. This and similar photodetectors would afford a capability for detecting single photons - a capability that is needed for research in quantum optics as well as for the practical development of secure optical communication systems for distribution of quantum cryptographic keys. The proposed photodetector would be of the hot-electron, phonon-cooled, thin-film superconductor type. The superconducting film in this device would be a meandering strip of niobium nitride. In the proposed photodetector, the quantum efficiency would be increased through incorporation of optiA design has been proposed for a photodetector that would exhibit a high quantum efficiency (as much as 90 percent) over a wide wavelength band, which would typically be centered at a wavelength of 1.55 m. This and similar photodetectors would afford a capability for detecting single photons - a capability that is needed for research in quantum optics as well as for the practical development of secure optical communication systems for distribution of quantum cryptographic keys. The proposed photodetector would be of the hot-electron, phonon-cooled, thin-film superconductor type. The superconducting film in this device would be a meandering strip of niobium nitride. In the proposed photodetector, the quantum efficiency would be increased through incorporation of opti-

Perovskite ink with wide processing window for scalable high-efficiency solar cells

DOE PAGES

Yang, Mengjin; Li, Zhen; Reese, Matthew O.; ...

2017-03-20

Perovskite solar cells have made tremendous progress using laboratory-scale spin-coating methods in the past few years owing to advances in controls of perovskite film deposition. However, devices made via scalable methods are still lagging behind state-of-the-art spin-coated devices because of the complicated nature of perovskite crystallization from a precursor state. Here we demonstrate a chlorine-containing methylammonium lead iodide precursor formulation along with solvent tuning to enable a wide precursor-processing window (up to ~8 min) and a rapid grain growth rate (as short as ~1 min). Coupled with antisolvent extraction, this precursor ink delivers high-quality perovskite films with large-scale uniformity. Themore » ink can be used by both spin-coating and blade-coating methods with indistinguishable film morphology and device performance. Using a blade-coated absorber, devices with 0.12-cm 2 and 1.2-cm 2 areas yield average efficiencies of 18.55% and 17.33%, respectively. As a result, we further demonstrate a 12.6-cm 2 four-cell module (88% geometric fill factor) with 13.3% stabilized active-area efficiency output.« less

Perovskite ink with wide processing window for scalable high-efficiency solar cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yang, Mengjin; Li, Zhen; Reese, Matthew O.

Perovskite solar cells have made tremendous progress using laboratory-scale spin-coating methods in the past few years owing to advances in controls of perovskite film deposition. However, devices made via scalable methods are still lagging behind state-of-the-art spin-coated devices because of the complicated nature of perovskite crystallization from a precursor state. Here we demonstrate a chlorine-containing methylammonium lead iodide precursor formulation along with solvent tuning to enable a wide precursor-processing window (up to ~8 min) and a rapid grain growth rate (as short as ~1 min). Coupled with antisolvent extraction, this precursor ink delivers high-quality perovskite films with large-scale uniformity. Themore » ink can be used by both spin-coating and blade-coating methods with indistinguishable film morphology and device performance. Using a blade-coated absorber, devices with 0.12-cm 2 and 1.2-cm 2 areas yield average efficiencies of 18.55% and 17.33%, respectively. As a result, we further demonstrate a 12.6-cm 2 four-cell module (88% geometric fill factor) with 13.3% stabilized active-area efficiency output.« less

Efficiency of the High Efficiency Total Absorption Spectrometer (HECTOR)

NASA Astrophysics Data System (ADS)

Sprowal, Zaire; Simon, Anna; Reingold, Craig; Spyrou, Artemis; Naqvi, Farheen; Dombos, Alexander; Palmisano, Alicia; Anderson, Tyler; Anderson, Samuel; Moylan, Shane; Seymour, Christopher; Skulski, Michael; Smith, Mallory K.; Strauss, Sabrina; Kolk, Byant Vande

2016-09-01

The p-process is a nucleosynthesis process that occurs in explosive environments such as type II and Ia supernovae and is responsible for production of heavy proton rich nuclei. Gamma rays emitted during these explosions induce several photo-disintegration reactions: (γ,n), (γ,p), and (γ , α). To study these interactions, the inverse of these reactions are measured experimentally. The High Efficiency TOtal absorption spectrometeR (HECTOR) at the University of Notre Dame was built for measuring these reactions. Standard gamma sources 60Co and 137Cs and known resonances in 27Al(p, γ)28Si reaction were used to experimentally determine HECTOR's summing efficiency. Here, the preliminary analysis will be presented and the results will be compared to the Geant4 simulation of the array. This work was supported by the National Science Foundation under the Grant Number PHYS-1614442.

Advanced gas turbine systems program

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zeh, C.M.

1995-06-01

The U.S. Department of Energy (DOE) is sponsoring a program to develop fuel-efficient gas turbine-based power systems with low emissions. DOE`s Office of Fossil Energy (DOE/FE) and Office of Energy Efficiency and Renewable Energy (DOE/EE) have initiated an 8-year program to develop high-efficiency, natural gas-fired advanced gas turbine power systems. The Advanced Turbine Systems (ATS) Program will support full-scale prototype demonstration of both industrial- and utility-scale systems that will provide commercial marketplace entries by the year 2000. When the program targets are met, power system emissions will be lower than from the best technology in use today. Efficiency of themore » utility-scale units will be greater than 60 percent on a lower heating value basis, and emissions of carbon dioxide will be reduced inversely with this increase. Industrial systems will also see an improvement of at least 15 percent in efficiency. Nitrogen oxides will be reduced by at least 10 percent, and carbon monoxide and hydrocarbon emissions will each be kept below 20 parts per million, for both utility and industrial systems.« less

High-efficiency organic glass scintillators

DOE Office of Scientific and Technical Information (OSTI.GOV)

Feng, Patrick L.; Carlson, Joseph S.

A new family of neutron/gamma discriminating scintillators is disclosed that comprises stable organic glasses that may be melt-cast into transparent monoliths. These materials have been shown to provide light yields greater than solution-grown trans-stilbene crystals and efficient PSD capabilities when combined with 0.01 to 0.05% by weight of the total composition of a wavelength-shifting fluorophore. Photoluminescence measurements reveal fluorescence quantum yields that are 2 to 5 times greater than conventional plastic or liquid scintillator matrices, which accounts for the superior light yield of these glasses. The unique combination of high scintillation light-yields, efficient neutron/gamma PSD, and straightforward scale-up via melt-castingmore » distinguishes the developed organic glasses from existing scintillators.« less

High efficiency photoionization detector

DOEpatents

Anderson, D.F.

1984-01-31

A high efficiency photoionization detector is described using tetraaminoethylenes in a gaseous state having a low ionization potential and a relative photoionization cross section which closely matches the emission spectrum of xenon gas. Imaging proportional counters are also disclosed using the novel photoionization detector of the invention. The compound of greatest interest is TMAE which comprises tetrakis(dimethylamino)ethylene which has a measured ionization potential of 5.36 [+-] 0.02 eV, and a vapor pressure of 0.35 torr at 20 C. 6 figs.

High-efficiency aperiodic two-dimensional high-contrast-grating hologram

NASA Astrophysics Data System (ADS)

Qiao, Pengfei; Zhu, Li; Chang-Hasnain, Connie J.

2016-03-01

High efficiency phase holograms are designed and implemented using aperiodic two-dimensional (2D) high-contrast gratings (HCGs). With our design algorithm and an in-house developed rigorous coupled-wave analysis (RCWA) package for periodic 2D HCGs, the structural parameters are obtained to achieve a full 360-degree phase-tuning range of the reflected or transmitted wave, while maintaining the power efficiency above 90%. For given far-field patterns or 3D objects to reconstruct, we can generate the near-field phase distribution through an iterative process. The aperiodic HCG phase plates we design for holograms are pixelated, and the local geometric parameters for each pixel to achieve desired phase alternation are extracted from our periodic HCG designs. Our aperiodic HCG holograms are simulated using the 3D finite-difference time-domain method. The simulation results confirm that the desired far-field patterns are successfully produced under illumination at the designed wavelength. The HCG holograms are implemented on the quartz wafers, using amorphous silicon as the high-index material. We propose HCG designs at both visible and infrared wavelengths, and our simulation confirms the reconstruction of 3D objects. The high-contrast gratings allow us to realize low-cost, compact, flat, and integrable holograms with sub-micrometer thicknesses.

Energy efficient engine preliminary design and integration study

NASA Technical Reports Server (NTRS)

Gray, D. E.

1978-01-01

The technology and configurational requirements of an all new 1990's energy efficient turbofan engine having a twin spool arrangement with a directly coupled fan and low-pressure turbine, a mixed exhaust nacelle, and a high 38.6:1 overall pressure ratio were studied. Major advanced technology design features required to provide the overall benefits were a high pressure ratio compression system, a thermally actuated advanced clearance control system, lightweight shroudless fan blades, a low maintenance cost one-stage high pressure turbine, a short efficient mixer and structurally integrated engine and nacelle. A conceptual design analysis was followed by integration and performance analyses of geared and direct-drive fan engines with separate or mixed exhaust nacelles to refine previously designed engine cycles. Preliminary design and more detailed engine-aircraft integration analysis were then conducted on the more promising configurations. Engine and aircraft sizing, fuel burned, and airframe noise studies on projected 1990's domestic and international aircraft produced sufficient definition of configurational and advanced technology requirements to allow immediate initiation of component technology development.

Stereotype Threat? Male and Female Students in Advanced High School Courses

NASA Astrophysics Data System (ADS)

Corra, Mamadi

Propositions of stereotype threat theory imply that the social consequences of academic distinction in advanced quantitative areas (such as math and the physical sciences) for women may promote the under representation of female students in advanced quantitative academic courses. The hypothesis that female students will be underrepresented in advanced quantitative (honors and advanced placement math and physical science) courses is tested using academic performance and enrollment data for high school students in a "Student/Parent Informed Choice" (open registration) school district in North Carolina. Results show female students to be overrepresented in both advanced verbal/writing intensive (honors and advanced placement English, foreign language, and social science) and advanced quantitative (honors and advanced placement math and physical science) courses compared to their proportion of the student body. More surprisingly, results also indicate female students (compared to male students) to be overrepresented in advanced courses compared to their proportion of high-performing students. Furthermore, as with patterns observed at the district level, additional analysis of enrollment data for the entire state reveals similar results. Taken together, the findings call into question the prevailing presumption that female students continue to be underrepresented in math and physical science courses. Instead, the changing social context within which females and males experience schooling may provide an explanation for the findings.

High-Order Dielectric Metasurfaces for High-Efficiency Polarization Beam Splitters and Optical Vortex Generators

NASA Astrophysics Data System (ADS)

Guo, Zhongyi; Zhu, Lie; Guo, Kai; Shen, Fei; Yin, Zhiping

2017-08-01

In this paper, a high-order dielectric metasurface based on silicon nanobrick array is proposed and investigated. By controlling the length and width of the nanobricks, the metasurfaces could supply two different incremental transmission phases for the X-linear-polarized (XLP) and Y-linear-polarized (YLP) light with extremely high efficiency over 88%. Based on the designed metasurface, two polarization beam splitters working in high-order diffraction modes have been designed successfully, which demonstrated a high transmitted efficiency. In addition, we have also designed two vortex-beam generators working in high-order diffraction modes to create vortex beams with the topological charges of 2 and 3. The employment of dielectric metasurfaces operating in high-order diffraction modes could pave the way for a variety of new ultra-efficient optical devices.

High-efficiency photovoltaic cells

DOEpatents

Yang, H.T.; Zehr, S.W.

1982-06-21

High efficiency solar converters comprised of a two cell, non-lattice matched, monolithic stacked semiconductor configuration using optimum pairs of cells having bandgaps in the range 1.6 to 1.7 eV and 0.95 to 1.1 eV, and a method of fabrication thereof, are disclosed. The high band gap subcells are fabricated using metal organic chemical vapor deposition (MOCVD), liquid phase epitaxy (LPE) or molecular beam epitaxy (MBE) to produce the required AlGaAs layers of optimized composition, thickness and doping to produce high performance, heteroface homojunction devices. The low bandgap subcells are similarly fabricated from AlGa(As)Sb compositions by LPE, MBE or MOCVD. These subcells are then coupled to form a monolithic structure by an appropriate bonding technique which also forms the required transparent intercell ohmic contact (IOC) between the two subcells. Improved ohmic contacts to the high bandgap semiconductor structure can be formed by vacuum evaporating to suitable metal or semiconductor materials which react during laser annealing to form a low bandgap semiconductor which provides a low contact resistance structure.

High Power Klystrons for Efficient Reliable High Power Amplifiers.

DTIC Science & Technology

1980-11-01

techniques to obtain high overall efficiency. One is second harmonic space charge bunching. This is a process whereby the fundamental and second harmonic...components of the space charge waves in the electron beam of a microwave tube are combined to produce more highly concentrated electron bunches raising the...the drift lengths to enhance the 2nd harmonic component in the space charge waves. The latter method was utilized in the VKC-7790. Computer

High-efficiency neutron detectors and methods of making same

DOEpatents

McGregor, Douglas S.; Klann, Raymond

2007-01-16

Neutron detectors, advanced detector process techniques and advanced compound film designs have greatly increased neutron-detection efficiency. One embodiment of the detectors utilizes a semiconductor wafer with a matrix of spaced cavities filled with one or more types of neutron reactive material such as ¹⁰B or ⁶LiF. The cavities are etched into both the front and back surfaces of the device such that the cavities from one side surround the cavities from the other side. The cavities may be etched via holes or etched slots or trenches. In another embodiment, the cavities are different-sized and the smaller cavities extend into the wafer from the lower surfaces of the larger cavities. In a third embodiment, multiple layers of different neutron-responsive material are formed on one or more sides of the wafer. The new devices operate at room temperature, are compact, rugged, and reliable in design.

Highly efficient organic electroluminescent diodes realized by efficient charge balance with optimized electron and hole transport layers

NASA Astrophysics Data System (ADS)

Khan, M. A.; Xu, Wei; Wei, Fuxiang; Bai, Yu; Jiang, X. Y.; Zhang, Z. L.; Zhu, W. Q.

2007-11-01

Highly efficient organic electroluminescent devices (OLEDs) were developed based on 4,7-diphenyl-1, 10-phenanthroline (BPhen) as the electron transport layer (ETL), tris-(8-hydroxyquinoline) aluminum (Alq 3) as the emission layer (EML) and N,Ń-bis-[1-naphthy(-N,Ńdiphenyl-1,1'-biphenyl-4,4'-diamine)] (NPB) as the hole transport layer (HTL). The typical device structure was glass substrate/ ITO/ NPB/ Alq 3/ BPhen/ LiF/ Al. Since BPhen possesses a considerable high electron mobility of 5×10 -4 cm 2 V -1 s -1, devices with BPhen as ETL can realize an extremely high luminous efficiency. By optimizing the thickness of both HTL and ETL, we obtained a highly efficient OLED with a current efficiency of 6.80 cd/A and luminance of 1361 cd/m 2 at a current density of 20 mA/cm 2. This dramatic improvement in the current efficiency has been explained on the principle of charge balance.

Optical signal processing for enabling high-speed, highly spectrally efficient and high capacity optical systems

NASA Astrophysics Data System (ADS)

Fazal, Muhammad Irfan

may be possible. Recently, interest has increased in exploring the spatial dimension of light to increase capacity, both in fiber as well as free-space communication channels. The orbital angular momentum (OAM) of light, carried by Laguerre-Gaussian (LG) beams have the interesting property that, in theory, an infinite number of OAMs can be transmitted; which due to its inherent orthogonality will not affect each other. Thus, in theory, one can increase the channel capacity arbitrarily. However, in practice, the device dimensions will reduce the number of OAMs used. In addition to advanced modulation formats, it is expected that optical signal processing may play a role in the future development of more efficient optical transmission systems. The hope is that performing signal processing in the optical domain may reduce optical-to-electronic conversion inefficiencies, eliminate bottlenecks and take advantage of the ultrahigh bandwidth inherent in optics. While 40 to 50 Gbit/s electronic components are the peak of commercial technology and 100 Gbit/s capable RF components are still in their infancy, optical signal processing of these high-speed data signals may provide a potential solution. Furthermore, any optical processing system or sub-system must be capable of handling the wide array of data formats and data rates that networks may employ. The work presented in this Ph.D. dissertation attempts at addressing the issue of optical processing for advanced optical modulation formats, and particularly explores the state of the art in increasing the capacity of an optical link by a combination of wavelength/phase/polarization/OAM dimensions of light. Spatial multiplexing and demultiplexing of both coherently and directly detected signals at the 100 Gbit/s Ethernet standard is addressed. The application of a continuously tunable all-optical delay for all-optical functionality like time-slot interchange at high data-rates is presented. Moreover the interplay of chirp

Resonantly pumped high efficiency Ho:YAG laser.

PubMed

Shen, Ying-Jie; Yao, Bao-Quan; Duan, Xiao-Ming; Dai, Tong-Yu; Ju, You-Lun; Wang, Yue-Zhu

2012-11-20

High-efficient CW and Q-switched Ho:YAG lasers resonantly dual-end-pumped by two diode-pumped Tm:YLF lasers at 1908 nm were investigated. A maximum slope efficiency of 74.8% in CW operation as well as a maximum output power of 58.7 W at 83.2 W incident pump power was achieved, which corresponded to an optical-to-optical conversion efficiency of 70.6%. The maximum pulse energy of 2.94 mJ was achieved, with a 31 ns FWHM pulse width and a peak power of approximately 94.7 kW.

High Efficiency mm-Wave Transmitter Array

DTIC Science & Technology

2016-09-01

SECURITY CLASSIFICATION OF: High efficiency, high power transmitters integrated in silicon at 45, 94 and 138 GHz were developed. Our approach...employs CMOS-SOI and SiGe HBT unit amplifiers, power -combined in free-space using antenna arrays to attain high power levels. In the baseline approach...the-art were made. At 45GHz, a single CMOS chip produced an RF power of 630mW, which yielded an EIRP of 1. REPORT DATE (DD-MM-YYYY) 4. TITLE AND

Bioblendstocks that Enable High Efficiency Engine Designs

DOE Office of Scientific and Technical Information (OSTI.GOV)

McCormick, Robert L.; Fioroni, Gina M.; Ratcliff, Matthew A.

2016-11-03

The past decade has seen a high level of innovation in production of biofuels from sugar, lipid, and lignocellulose feedstocks. As discussed in several talks at this workshop, ethanol blends in the E25 to E50 range could enable more highly efficient spark-ignited (SI) engines. This is because of their knock resistance properties that include not only high research octane number (RON), but also charge cooling from high heat of vaporization, and high flame speed. Emerging alcohol fuels such as isobutanol or mixed alcohols have desirable properties such as reduced gasoline blend vapor pressure, but also have lower RON than ethanol.more » These fuels may be able to achieve the same knock resistance benefits, but likely will require higher blend levels or higher RON hydrocarbon blendstocks. A group of very high RON (>150) oxygenates such as dimethyl furan, methyl anisole, and related compounds are also produced from biomass. While providing no increase in charge cooling, their very high octane numbers may provide adequate knock resistance for future highly efficient SI engines. Given this range of options for highly knock resistant fuels there appears to be a critical need for a fuel knock resistance metric that includes effects of octane number, heat of vaporization, and potentially flame speed. Emerging diesel fuels include highly branched long-chain alkanes from hydroprocessing of fats and oils, as well as sugar-derived terpenoids. These have relatively high cetane number (CN), which may have some benefits in designing more efficient CI engines. Fast pyrolysis of biomass can produce diesel boiling range streams that are high in aromatic, oxygen and acid contents. Hydroprocessing can be applied to remove oxygen and consequently reduce acidity, however there are strong economic incentives to leave up to 2 wt% oxygen in the product. This oxygen will primarily be present as low CN alkyl phenols and aryl ethers. While these have high heating value, their presence in

Highly-efficient all-dielectric Huygens' surface holograms (Conference Presentation)

NASA Astrophysics Data System (ADS)

Chong, Katie; Wang, Lei; Staude, Isabelle; James, Anthony; Dominguez, Jason; Subramania, Ganapathi; Liu, Sheng; Decker, Manuel; Neshev, Dragomir N.; Brener, Igal; Kivshar, Yuri S.

2016-04-01

Optical metasurfaces have developed as a breakthrough concept for advanced wave-front. Key to these "designer metasurfaces"[1] is that they provide full 360 degree phase coverage and that their local phase can be precisely controlled. The local control of phase, amplitude and polarization on an optically thin plane will lead to a new class of flat optical components in the areas of integrated optics, flat displays, energy harvesting and mid-infrared photonics, with increased performance and functionality. However, reflection and/or absorption losses as well as low polarization-conversion efficiencies pose a fundamental obstacle for achieving high transmission efficiencies that are required for practical applications. A promising way to overcome these limitations is the use of metamaterial Huygens' surfaces [2-4], i.e., reflection-less surfaces that can also provide full 360 degree phase coverage in transmission. Plasmonic implementations of Huygens' surfaces for microwave [2] and the mid-infrared spectral range [3], where the intrinsic losses of the metals are negligible, have been suggested, however, these designs cannot be transferred to near-infrared or even visible frequencies because of the high dissipative losses of plasmonic structures at optical frequencies. Here, we demonstrate the first holographic metasurface utilizing the concept of all-dielectric Huygens' surfaces thereby achieving record transmission efficiencies of approximately 82% at 1477nm wavelength. Our low-loss Huygens' surface is realized by two-dimensional subwavelength arrays of loss-less silicon nanodisks with both electric and magnetic dipole resonances [4]. By controlling the intrinsic properties of the resonances, i.e. their relative electric and magnetic polarizabilities, quality factors and spectral position, we can design silicon nanodisks to behave as near-ideal Huygens' particles. This allows us to realize all-dielectric Huygens' surfaces providing full 360 degree phase coverage

Advanced high temperature thermoelectrics for space power

NASA Technical Reports Server (NTRS)

Lockwood, A.; Ewell, R.; Wood, C.

1981-01-01

Preliminary results from a spacecraft system study show that an optimum hot junction temperature is in the range of 1500 K for advanced nuclear reactor technology combined with thermoelectric conversion. Advanced silicon germanium thermoelectric conversion is feasible if hot junction temperatures can be raised roughly 100 C or if gallium phosphide can be used to improve the figure of merit, but the performance is marginal. Two new classes of refractory materials, rare earth sulfides and boron-carbon alloys, are being investigated to improve the specific weight of the generator system. Preliminary data on the sulfides have shown very high figures of merit over short temperature ranges. Both n- and p-type doping have been obtained. Pure boron-carbide may extrapolate to high figure of merit at temperatures well above 1500 K but not lower temperature; n-type conduction has been reported by others, but not yet observed in the JPL program. Inadvertant impurity doping may explain the divergence of results reported.

High-efficiency crystalline silicon technology development

NASA Technical Reports Server (NTRS)

Prince, M. B.

1984-01-01

The rationale for pursuing high efficiency crystalline silicon technology research is discussed. Photovoltaic energy systems are reviewed as to their cost effectiveness and their competitiveness with other energy systems. The parameters of energy system life are listed and briefly reviewed.

A high-efficiency thermoelectric converter for space applications

DOE Office of Scientific and Technical Information (OSTI.GOV)

Metzger, J.D.; El-Genk, M.S.

1990-01-01

This paper presents a concept for using high-temperature superconducting materials in thermoelectric generators (SCTE) to produce electricity at conversion efficiencies approaching 50% of the Carrot efficiency. The SCTE generator is applicable to systems operating in temperature ranges of high-temperature superconducting materials and thus would be a low-grade converter. Operating in cryogenic temperature ranges provides the advantage of inherently increasing the limits of the Carrot efficiency. Potential applications are for systems operating in space where the ambient temperatures are in the cryogenic temperature range. The advantage of using high-temperature superconducting material in a thermoelectric converter is that it would significantly reducemore » or eliminate the Joule heating losses in a thermoelectric element. This paper investigates the system aspects and the material requirements of the SCTE converter concept, and presents a conceptual design and an application for a space power system.« less

A high-efficiency thermoelectric converter for space applications

DOE Office of Scientific and Technical Information (OSTI.GOV)

Metzger, J.D.; El-Genk, M.S.

1990-12-31

This paper presents a concept for using high-temperature superconducting materials in thermoelectric generators (SCTE) to produce electricity at conversion efficiencies approaching 50% of the Carrot efficiency. The SCTE generator is applicable to systems operating in temperature ranges of high-temperature superconducting materials and thus would be a low-grade converter. Operating in cryogenic temperature ranges provides the advantage of inherently increasing the limits of the Carrot efficiency. Potential applications are for systems operating in space where the ambient temperatures are in the cryogenic temperature range. The advantage of using high-temperature superconducting material in a thermoelectric converter is that it would significantly reducemore » or eliminate the Joule heating losses in a thermoelectric element. This paper investigates the system aspects and the material requirements of the SCTE converter concept, and presents a conceptual design and an application for a space power system.« less

Advanced Packaging Materials and Techniques for High Power TR Module: Standard Flight vs. Advanced Packaging

NASA Technical Reports Server (NTRS)

Hoffman, James Patrick; Del Castillo, Linda; Miller, Jennifer; Jenabi, Masud; Hunter, Donald; Birur, Gajanana

2011-01-01

The higher output power densities required of modern radar architectures, such as the proposed DESDynI [Deformation, Ecosystem Structure, and Dynamics of Ice] SAR [Synthetic Aperture Radar] Instrument (or DSI) require increasingly dense high power electronics. To enable these higher power densities, while maintaining or even improving hardware reliability, requires advances in integrating advanced thermal packaging technologies into radar transmit/receive (TR) modules. New materials and techniques have been studied and compared to standard technologies.

High-speed and high-efficiency travelling wave single-photon detectors embedded in nanophotonic circuits

PubMed Central

Pernice, W.H.P.; Schuck, C.; Minaeva, O.; Li, M.; Goltsman, G.N.; Sergienko, A.V.; Tang, H.X.

2012-01-01

Ultrafast, high-efficiency single-photon detectors are among the most sought-after elements in modern quantum optics and quantum communication. However, imperfect modal matching and finite photon absorption rates have usually limited their maximum attainable detection efficiency. Here we demonstrate superconducting nanowire detectors atop nanophotonic waveguides, which enable a drastic increase of the absorption length for incoming photons. This allows us to achieve high on-chip single-photon detection efficiency up to 91% at telecom wavelengths, repeatable across several fabricated chips. We also observe remarkably low dark count rates without significant compromise of the on-chip detection efficiency. The detectors are fully embedded in scalable silicon photonic circuits and provide ultrashort timing jitter of 18 ps. Exploiting this high temporal resolution, we demonstrate ballistic photon transport in silicon ring resonators. Our direct implementation of a high-performance single-photon detector on chip overcomes a major barrier in integrated quantum photonics. PMID:23271658

Charge transport in highly efficient iridium cored electrophosphorescent dendrimers

NASA Astrophysics Data System (ADS)

Markham, Jonathan P. J.; Samuel, Ifor D. W.; Lo, Shih-Chun; Burn, Paul L.; Weiter, Martin; Bässler, Heinz

2004-01-01

Electrophosphorescent dendrimers are promising materials for highly efficient light-emitting diodes. They consist of a phosphorescent core onto which dendritic groups are attached. Here, we present an investigation into the optical and electronic properties of highly efficient phosphorescent dendrimers. The effect of dendrimer structure on charge transport and optical properties is studied using temperature-dependent charge-generation-layer time-of-flight measurements and current voltage (I-V) analysis. A model is used to explain trends seen in the I-V characteristics. We demonstrate that fine tuning the mobility by chemical structure is possible in these dendrimers and show that this can lead to highly efficient bilayer dendrimer light-emitting diodes with neat emissive layers. Power efficiencies of 20 lm/W were measured for devices containing a second-generation (G2) Ir(ppy)3 dendrimer with a 1,3,5-tris(2-N-phenylbenzimidazolyl)benzene electron transport layer.

High efficiency compound semiconductor concentrator photovoltaics

NASA Technical Reports Server (NTRS)

Borden, P.; Gregory, P.; Saxena, R.; Owen, R.; Moore, O.

1980-01-01

Special emphasis was given to the high yield pilot production of packaged AlGaAs/GaAs concentrator solar cells, using organometallic VPE for materials growth, the demonstration of a concentrator module using 12 of these cells which achieved 16.4 percent conversion efficiency at 50 C coolant inlet temperature, and the demonstration of a spectral splitting converter module that achieved in excess of 20 percent efficiency. This converter employed ten silicon and ten AlGaAs cells with a dichroic filter functioning as the beam splitter. A monolithic array of AlGaAs/GaAs solar cells is described.

United by Goals: There Is No Integrated Advancement without Communications and Marketing

ERIC Educational Resources Information Center

DiConsiglio, John

2011-01-01

The idea behind integrated advancement is simple and dates back to the 1990s: A strong relationship between advancement offices conserves resources. It leads to a more efficient workforce. It portrays a highly unified message to stakeholders, including donors, alumni, local officials, and opinion leaders. In short, the entire advancement team…

High-efficiency solar cell and method for fabrication

DOEpatents

Hou, Hong Q.; Reinhardt, Kitt C.

1999-01-01

A high-efficiency 3- or 4-junction solar cell is disclosed with a theoretical AM0 energy conversion efficiency of about 40%. The solar cell includes p-n junctions formed from indium gallium arsenide nitride (InGaAsN), gallium arsenide (GaAs) and indium gallium aluminum phosphide (InGaAlP) separated by n-p tunnel junctions. An optional germanium (Ge) p-n junction can be formed in the substrate upon which the other p-n junctions are grown. The bandgap energies for each p-n junction are tailored to provide substantially equal short-circuit currents for each p-n junction, thereby eliminating current bottlenecks and improving the overall energy conversion efficiency of the solar cell. Additionally, the use of an InGaAsN p-n junction overcomes super-bandgap energy losses that are present in conventional multi-junction solar cells. A method is also disclosed for fabricating the high-efficiency 3- or 4-junction solar cell by metal-organic chemical vapor deposition (MOCVD).

Electrical efficiency and droop in MQW LEDs

NASA Astrophysics Data System (ADS)

Malyutenko, V. K.

2014-02-01

It is believed that low power conversion efficiency in commercial MQW LEDs occurs as a result of efficiency droop, current-induced dynamic degradation of the internal quantum efficiency, injection efficiency, and extraction efficiency. Broadly speaking, all these "quenching" mechanisms could be referred to as the optical losses. The vast advances of high-power InGaN and AlGaInP MQW LEDs have been achieved by addressing these losses. In contrast to these studies, in this paper we consider an alternative approach to make high-power LEDs more efficient. We identify current-induced electrical efficiency degradation (EED) as a strong limiting factor of power conversion efficiency. We found that EED is caused by current crowding followed by an increase in current-induced series resistance of a device. By decreasing the current spreading length, EED also causes the optical efficiency to degrade and stands for an important aspect of LED performance. This paper gives scientists the opportunity to look for different attributes of EED.

Overview of Advanced Turbine Systems Program

NASA Astrophysics Data System (ADS)

Webb, H. A.; Bajura, R. A.

The US Department of Energy initiated a program to develop advanced gas turbine systems to serve both central power and industrial power generation markets. The Advanced Turbine Systems (ATS) Program will lead to commercial offerings by the private sector by 2002. ATS will be developed to fire natural gas but will be adaptable to coal and biomass firing. The systems will be: highly efficient (15 percent improvement over today's best systems); environmentally superior (10 percent reduction in nitrogen oxides over today's best systems); and cost competitive (10 percent reduction in cost of electricity). The ATS Program has five elements. Innovative cycle development will lead to the demonstration of systems with advanced gas turbine cycles using current gas turbine technology. High temperature development will lead to the increased firing temperatures needed to achieve ATS Program efficiency goals. Ceramic component development/demonstration will expand the current DOE/CE program to demonstrate industrial-scale turbines with ceramic components. Technology base will support the overall program by conducting research and development (R&D) on generic technology issues. Coal application studies will adapt technology developed in the ATS program to coal-fired systems being developed in other DOE programs.

Energy efficient engine high-pressure turbine supersonic cascade technology report

NASA Technical Reports Server (NTRS)

Kopper, F. C.; Milano, R.; Davis, R. L.; Dring, R. P.; Stoeffler, R. C.

1981-01-01

The performance of two vane endwall geometries and three blade sections for the high-pressure turbine was evaluated in terms of the efficiency requirements of the Energy Efficient Engine high-pressure turbine component. The van endwall designs featured a straight wall and S-wall configuration. The blade designs included a base blade, straightback blade, and overcambered blade. Test results indicated that the S-wall vane configuration and the base blade configuration offered the most promising performance characteristics for the Energy Efficient Engine high-pressure turbine component.

Advanced Gouy phase high harmonics interferometer

NASA Astrophysics Data System (ADS)

Mustary, M. H.; Laban, D. E.; Wood, J. B. O.; Palmer, A. J.; Holdsworth, J.; Litvinyuk, I. V.; Sang, R. T.

2018-05-01

We describe an extreme ultraviolet (XUV) interferometric technique that can resolve ∼100 zeptoseconds (10‑21 s) delay between high harmonic emissions from two successive sources separated spatially along the laser propagation in a single Gaussian beam focus. Several improvements on our earlier work have been implemented in the advanced interferometer. In this paper, we report on the design, characterization and optimization of the advanced Gouy phase interferometer. Temporal coherence for both atomic argon and molecular hydrogen gases has been observed for several harmonic orders. It has been shown that phase shift of XUV pulses mainly originates from the emission time delay due to the Gouy phase in the laser focus and the observed interference is independent of the generating medium. This interferometer can be a useful tool for measuring the relative phase shift between any two gas species and for studying ultrafast dynamics of their electronic and nuclear motion.

Operational efficiency subpanel advanced mission control

NASA Technical Reports Server (NTRS)

Friedland, Peter

1990-01-01

Herein, the term mission control will be taken quite broadly to include both ground and space based operations as well as the information infrastructure necessary to support such operations. Three major technology areas related to advanced mission control are examined: (1) Intelligent Assistance for Ground-Based Mission Controllers and Space-Based Crews; (2) Autonomous Onboard Monitoring, Control and Fault Detection Isolation and Reconfiguration; and (3) Dynamic Corporate Memory Acquired, Maintained, and Utilized During the Entire Vehicle Life Cycle. The current state of the art space operations are surveyed both within NASA and externally for each of the three technology areas and major objectives are discussed from a user point of view for technology development. Ongoing NASA and other governmental programs are described. An analysis of major research issues and current holes in the program are provided. Several recommendations are presented for enhancing the technology development and insertion process to create advanced mission control environments.

A generic concept to overcome bandgap limitations for designing highly efficient multi-junction photovoltaic cells

PubMed Central

Guo, Fei; Li, Ning; Fecher, Frank W.; Gasparini, Nicola; Quiroz, Cesar Omar Ramirez; Bronnbauer, Carina; Hou, Yi; Radmilović, Vuk V.; Radmilović, Velimir R.; Spiecker, Erdmann; Forberich, Karen; Brabec, Christoph J.

2015-01-01

The multi-junction concept is the most relevant approach to overcome the Shockley–Queisser limit for single-junction photovoltaic cells. The record efficiencies of several types of solar technologies are held by series-connected tandem configurations. However, the stringent current-matching criterion presents primarily a material challenge and permanently requires developing and processing novel semiconductors with desired bandgaps and thicknesses. Here we report a generic concept to alleviate this limitation. By integrating series- and parallel-interconnections into a triple-junction configuration, we find significantly relaxed material selection and current-matching constraints. To illustrate the versatile applicability of the proposed triple-junction concept, organic and organic-inorganic hybrid triple-junction solar cells are constructed by printing methods. High fill factors up to 68% without resistive losses are achieved for both organic and hybrid triple-junction devices. Series/parallel triple-junction cells with organic, as well as perovskite-based subcells may become a key technology to further advance the efficiency roadmap of the existing photovoltaic technologies. PMID:26177808

A generic concept to overcome bandgap limitations for designing highly efficient multi-junction photovoltaic cells.

PubMed

Guo, Fei; Li, Ning; Fecher, Frank W; Gasparini, Nicola; Ramirez Quiroz, Cesar Omar; Bronnbauer, Carina; Hou, Yi; Radmilović, Vuk V; Radmilović, Velimir R; Spiecker, Erdmann; Forberich, Karen; Brabec, Christoph J

2015-07-16

The multi-junction concept is the most relevant approach to overcome the Shockley-Queisser limit for single-junction photovoltaic cells. The record efficiencies of several types of solar technologies are held by series-connected tandem configurations. However, the stringent current-matching criterion presents primarily a material challenge and permanently requires developing and processing novel semiconductors with desired bandgaps and thicknesses. Here we report a generic concept to alleviate this limitation. By integrating series- and parallel-interconnections into a triple-junction configuration, we find significantly relaxed material selection and current-matching constraints. To illustrate the versatile applicability of the proposed triple-junction concept, organic and organic-inorganic hybrid triple-junction solar cells are constructed by printing methods. High fill factors up to 68% without resistive losses are achieved for both organic and hybrid triple-junction devices. Series/parallel triple-junction cells with organic, as well as perovskite-based subcells may become a key technology to further advance the efficiency roadmap of the existing photovoltaic technologies.

Energy efficient engine: High pressure turbine uncooled rig technology report

NASA Technical Reports Server (NTRS)

Gardner, W. B.

1979-01-01

Results obtained from testing five performance builds (three vane cascades and two rotating rigs of the Energy Efficient Engine uncooled rig have established the uncooled aerodynamic efficiency of the high-pressure turbine at 91.1 percent. This efficiency level was attained by increasing the rim speed and annulus area (AN(2)), and by increasing the turbine reaction level. The increase in AN(2) resulted in a performance improvement of 1.15 percent. At the design point pressure ratio, the increased reaction level rig demonstrated an efficiency of 91.1 percent. The results of this program have verified the aerodynamic design assumptions established for the Energy Efficient Engine high-pressure turbine component.

808nm high-power high-efficiency GaAsP/GaInP laser bars

NASA Astrophysics Data System (ADS)

Wang, Ye; Yang, Ye; Qin, Li; Wang, Chao; Yao, Di; Liu, Yun; Wang, Lijun

2008-11-01

808nm high power diode lasers, which is rapidly maturing technology technically and commercially since the introduction in 1999 of complete kilowatt-scale diode laser systems, have important applications in the fields of industry and pumping solid-state lasers (DPSSL). High power and high power conversion efficiency are extremely important in diode lasers, and they could lead to new applications where space, weight and electrical power are critical. High efficiency devices generate less waste heat, which means less strain on the cooling system and more tolerance to thermal conductivity variation, a lower junction temperature and longer lifetimes. Diode lasers with Al-free materials have superior power conversion efficiency compared with conventional AlGaAs/GaAs devices because of their lower differential series resistance and higher thermal conductivity. 808nm GaAsP/GaInP broad-waveguide emitting diode laser bars with 1mm cavity length have been fabricated. The peak power can reach to 100.9W at 106.5A at quasicontinuous wave operation (200μs, 1000Hz). The maximum power conversion efficiency is 57.38%. Based on these high power laser bars, we fabricate a 1x3 arrays, the maximum power is 64.3W in continuous wave mode when the current is 25.0A. And the threshold current is 5.9A, the slope efficiency is 3.37 W/A.

Assessment of advanced technologies for high performance single-engine business airplanes

NASA Technical Reports Server (NTRS)

Kohlman, D. L.; Holmes, B. J.

1982-01-01

The prospects for significantly increasing the fuel efficiency and mission capability of single engine business aircraft through the incorporation of advanced propulsion, aerodynamics and materials technologies are explored. It is found that turbine engines cannot match the fuel economy of the heavier rotary, diesel and advanced spark reciprocating engines. The rotary engine yields the lightest and smallest aircraft for a given mission requirement, and also offers greater simplicity and a multifuel capability. Great promise is also seen in the use of composite material primary structures in conjunction with laminar flow wing surfaces, a pusher propeller and conventional wing-tail configuration. This study was conducted with the General Aviation Synthesis Program, which can furnish the most accurate mission performance calculations yet obtained.

Energy efficient transport technology: Program summary and bibliography

NASA Technical Reports Server (NTRS)

Middleton, D. B.; Bartlett, D. W.; Hood, R. V.

1985-01-01

The Energy Efficient Transport (EET) Program began in 1976 as an element of the NASA Aircraft Energy Efficiency (ACEE) Program. The EET Program and the results of various applications of advanced aerodynamics and active controls technology (ACT) as applicable to future subsonic transport aircraft are discussed. Advanced aerodynamics research areas included high aspect ratio supercritical wings, winglets, advanced high lift devices, natural laminar flow airfoils, hybrid laminar flow control, nacelle aerodynamic and inertial loads, propulsion/airframe integration (e.g., long duct nacelles) and wing and empennage surface coatings. In depth analytical/trade studies, numerous wind tunnel tests, and several flight tests were conducted. Improved computational methodology was also developed. The active control functions considered were maneuver load control, gust load alleviation, flutter mode control, angle of attack limiting, and pitch augmented stability. Current and advanced active control laws were synthesized and alternative control system architectures were developed and analyzed. Integrated application and fly by wire implementation of the active control functions were design requirements in one major subprogram. Additional EET research included interdisciplinary technology applications, integrated energy management, handling qualities investigations, reliability calculations, and economic evaluations related to fuel savings and cost of ownership of the selected improvements.

High efficiency and broadband acoustic diodes

NASA Astrophysics Data System (ADS)

Fu, Congyi; Wang, Bohan; Zhao, Tianfei; Chen, C. Q.

2018-01-01

Energy transmission efficiency and working bandwidth are the two major factors limiting the application of current acoustic diodes (ADs). This letter presents a design of high efficiency and broadband acoustic diodes composed of a nonlinear frequency converter and a linear wave filter. The converter consists of two masses connected by a bilinear spring with asymmetric tension and compression stiffness. The wave filter is a linear mass-spring lattice (sonic crystal). Both numerical simulation and experiment show that the energy transmission efficiency of the acoustic diode can be improved by as much as two orders of magnitude, reaching about 61%. Moreover, the primary working band width of the AD is about two times of the cut-off frequency of the sonic crystal filter. The cut-off frequency dependent working band of the AD implies that the developed AD can be scaled up or down from macro-scale to micro- and nano-scale.

Experimental Realization of High-Efficiency Counterfactual Computation.

PubMed

Kong, Fei; Ju, Chenyong; Huang, Pu; Wang, Pengfei; Kong, Xi; Shi, Fazhan; Jiang, Liang; Du, Jiangfeng

2015-08-21

Counterfactual computation (CFC) exemplifies the fascinating quantum process by which the result of a computation may be learned without actually running the computer. In previous experimental studies, the counterfactual efficiency is limited to below 50%. Here we report an experimental realization of the generalized CFC protocol, in which the counterfactual efficiency can break the 50% limit and even approach unity in principle. The experiment is performed with the spins of a negatively charged nitrogen-vacancy color center in diamond. Taking advantage of the quantum Zeno effect, the computer can remain in the not-running subspace due to the frequent projection by the environment, while the computation result can be revealed by final detection. The counterfactual efficiency up to 85% has been demonstrated in our experiment, which opens the possibility of many exciting applications of CFC, such as high-efficiency quantum integration and imaging.

Experimental Realization of High-Efficiency Counterfactual Computation

NASA Astrophysics Data System (ADS)

Kong, Fei; Ju, Chenyong; Huang, Pu; Wang, Pengfei; Kong, Xi; Shi, Fazhan; Jiang, Liang; Du, Jiangfeng

2015-08-01

Counterfactual computation (CFC) exemplifies the fascinating quantum process by which the result of a computation may be learned without actually running the computer. In previous experimental studies, the counterfactual efficiency is limited to below 50%. Here we report an experimental realization of the generalized CFC protocol, in which the counterfactual efficiency can break the 50% limit and even approach unity in principle. The experiment is performed with the spins of a negatively charged nitrogen-vacancy color center in diamond. Taking advantage of the quantum Zeno effect, the computer can remain in the not-running subspace due to the frequent projection by the environment, while the computation result can be revealed by final detection. The counterfactual efficiency up to 85% has been demonstrated in our experiment, which opens the possibility of many exciting applications of CFC, such as high-efficiency quantum integration and imaging.

Barriers to applying advanced high-temperature materials

NASA Astrophysics Data System (ADS)

Premkumar, M. K.

1993-01-01

During the past 25 years, aerospace engineers and material scientists have made significant technical progress toward developing next-generation aircraft. However, while advanced high-temperature materials continue to be developed, the outlook for their future application is uncertain and will depend on the ability of these materials to satisfy a more diverse market.

Aerodynamic Design Study of Advanced Multistage Axial Compressor

NASA Technical Reports Server (NTRS)

Larosiliere, Louis M.; Wood, Jerry R.; Hathaway, Michael D.; Medd, Adam J.; Dang, Thong Q.

2002-01-01

As a direct response to the need for further performance gains from current multistage axial compressors, an investigation of advanced aerodynamic design concepts that will lead to compact, high-efficiency, and wide-operability configurations is being pursued. Part I of this report describes the projected level of technical advancement relative to the state of the art and quantifies it in terms of basic aerodynamic technology elements of current design systems. A rational enhancement of these elements is shown to lead to a substantial expansion of the design and operability space. Aerodynamic design considerations for a four-stage core compressor intended to serve as a vehicle to develop, integrate, and demonstrate aerotechnology advancements are discussed. This design is biased toward high efficiency at high loading. Three-dimensional blading and spanwise tailoring of vector diagrams guided by computational fluid dynamics (CFD) are used to manage the aerodynamics of the high-loaded endwall regions. Certain deleterious flow features, such as leakage-vortex-dominated endwall flow and strong shock-boundary-layer interactions, were identified and targeted for improvement. However, the preliminary results were encouraging and the front two stages were extracted for further aerodynamic trimming using a three-dimensional inverse design method described in part II of this report. The benefits of the inverse design method are illustrated by developing an appropriate pressure-loading strategy for transonic blading and applying it to reblade the rotors in the front two stages of the four-stage configuration. Multistage CFD simulations based on the average passage formulation indicated an overall efficiency potential far exceeding current practice for the front two stages. Results of the CFD simulation at the aerodynamic design point are interrogated to identify areas requiring additional development. In spite of the significantly higher aerodynamic loadings, advanced CFD

Realization of highly efficient hexagonal boron nitride neutron detectors

DOE PAGES

Maity, A.; Doan, T. C.; Li, J.; ...

2016-08-16

Here, we report the achievement of highly efficient 10B enriched hexagonal boron nitride (h- 10BN) direct conversion neutron detectors. These detectors were realized from freestanding 4-in. diameter h- 10BN wafers 43 μm in thickness obtained from epitaxy growth and subsequent mechanical separation from sapphire substrates. Both sides of the film were subjected to ohmic contact deposition to form a simple vertical “photoconductor-type” detector. Transport measurements revealed excellent vertical transport properties including high electrical resistivity (>10 13 Ω cm) and mobility-lifetime (μτ) products. A much larger μτ product for holes compared to that of electrons along the c-axis of h- BNmore » was observed, implying that holes (electrons) behave like majority (minority) carriers in undoped h- BN. Exposure to thermal neutrons from a californium-252 ( 252Cf) source moderated by a high density polyethylene moderator reveals that 43 μm h- 10BN detectors possess 51.4% detection efficiency at a bias voltage of 400 V, which is the highest reported efficiency for any semiconductor-based neutron detector. The results point to the possibility of obtaining highly efficient, compact solid-state neutron detectors with high gamma rejection and low manufacturing and maintenance costs.« less

Optically efficient InAsSb nanowires for silicon-based mid-wavelength infrared optoelectronics.

PubMed

Zhuang, Q D; Alradhi, H; Jin, Z M; Chen, X R; Shao, J; Chen, X; Sanchez, Ana M; Cao, Y C; Liu, J Y; Yates, P; Durose, K; Jin, C J

2017-03-10

InAsSb nanowires (NWs) with a high Sb content have potential in the fabrication of advanced silicon-based optoelectronics such as infrared photondetectors/emitters and highly sensitive phototransistors, as well as in the generation of renewable electricity. However, producing optically efficient InAsSb NWs with a high Sb content remains a challenge, and optical emission is limited to 4.0 μm due to the quality of the nanowires. Here, we report, for the first time, the success of high-quality and optically efficient InAsSb NWs enabling silicon-based optoelectronics operating in entirely mid-wavelength infrared. Pure zinc-blende InAsSb NWs were realized with efficient photoluminescence emission. We obtained room-temperature photoluminescence emission in InAs NWs and successfully extended the emission wavelength in InAsSb NWs to 5.1 μm. The realization of this optically efficient InAsSb NW material paves the way to realizing next-generation devices, combining advances in III-V semiconductors and silicon.

Recent Advances in the Synthesis of High Explosive Materials

DTIC Science & Technology

2015-12-29

explosives and secondary high explosives, and the sensitivities and properties of these molecules are provided. In addition to the synthesis of such materials...This review discusses the recent advances in the syntheses of high explosive energetic materials. Syntheses of some relevant modern primary

High-power ultrasonic processing: Recent developments and prospective advances

NASA Astrophysics Data System (ADS)

Gallego-Juarez, Juan A.

2010-01-01

Although the application of ultrasonic energy to produce or to enhance a wide variety of processes have been explored since about the middle of the 20th century, only a reduced number of ultrasonic processes have been established at industrial level. However, during the last ten years the interest in ultrasonic processing has revived particularly in industrial sectors where the ultrasonic technology may represent a clean and efficient tool to improve classical existing processes or an innovation alternative for the development of new processes. Such seems to be the case of relevant sectors such as food industry, environment, pharmaceuticals and chemicals manufacture, machinery, mining, etc where power ultrasound is becoming an emerging technology for process development. The possible major problem in the application of high-intensity ultrasound on industrial processing is the design and development of efficient power ultrasonic systems (generators and reactors) capable of large scale successful operation specifically adapted to each individual process. In the area of ultrasonic processing in fluid media and more specifically in gases, the development of the steppedplate transducers and other power ge with extensive radiating surface has strongly contributed to the implementation at semi-industrial and industrial stage of several commercial applications, in sectors such as food and beverage industry (defoaming, drying, extraction, etc), environment (air cleaning, sludge filtration, etc...), machinery and process for manufacturing (textile washing, paint manufacture, etc). The development of different cavitational reactors for liquid treatment in continuous flow is helping to introduce into industry the wide potential of the area of sonochemistry. Processes such as water and effluent treatment, crystallization, soil remediation, etc have been already implemented at semi-industrial and/or industrial stage. Other single advances in sectors like mining or energy have

Space Photovoltaic Research and Technology, 1988. High Efficiency, Space Environment, and Array Technology

NASA Technical Reports Server (NTRS)

1989-01-01

The 9th Space Photovoltaic Research and Technology conference was held at the NASA Lewis Research Center from April 19 to 21, 1988. The papers and workshop summaries report remarkable progress on a wide variety of approaches in space photovoltaics, for both near and far term applications. Among the former is the recently developed high efficiency GaAs/Ge cell, which formed the focus of a workshop discussion on heteroepitaxial cells. Still aimed at the long term, but with a significant payoff in a new mission capability, are InP cells, with their potentially dramatic improvement in radiation resistance. Approaches to near term, array specific powers exceeding 130 W/kg are also reported, and advanced concentrator panel technology with the potential to achieve over 250 W/sq m is beginning to take shape.

High efficiency crystalline silicon solar cells

NASA Technical Reports Server (NTRS)

Sah, C. Tang

1986-01-01

A review of the entire research program since its inception ten years ago is given. The initial effort focused on the effects of impurities on the efficiency of silicon solar cells to provide figures of maximum allowable impurity density for efficiencies up to about 16 to 17%. Highly accurate experimental techniques were extended to characterize the recombination properties of the residual imputities in the silicon solar cell. A numerical simulator of the solar cell was also developed, using the Circuit Technique for Semiconductor Analysis. Recent effort focused on the delineation of the material and device parameters which limited the silicon efficiency to below 20% and on an investigation of cell designs to break the 20% barrier. Designs of the cell device structure and geometry can further reduce recombination losses as well as the sensitivity and criticalness of the fabrication technology required to exceed 20%. Further research is needed on the fundamental characterization of the carrier recombination properties at the chemical impurity and physical defect centers. It is shown that only single crystalline silicon cell technology can be successful in attaining efficiencies greater than 20%.

An efficient liner cooling scheme for advanced small gas turbine combustors

NASA Technical Reports Server (NTRS)

Paskin, Marc D.; Mongia, Hukam C.; Acosta, Waldo A.

1993-01-01

A joint Army/NASA program was conducted to design, fabricate, and test an advanced, small gas turbine, reverse-flow combustor utilizing a compliant metal/ceramic (CMC) wall cooling concept. The objectives of this effort were to develop a design method (basic design data base and analysis) for the CMC cooling technique and then demonstrate its application to an advanced cycle, small, reverse-flow combustor with 3000 F burner outlet temperature. The CMC concept offers significant improvements in wall cooling effectiveness resulting in a large reduction in cooling air requirements. Therefore, more air is available for control of burner outlet temperature pattern in addition to the benefits of improved efficiency, reduced emissions, and lower smoke levels. The program was divided into four tasks. Task 1 defined component materials and localized design of the composite wall structure in conjunction with development of basic design models for the analysis of flow and heat transfer through the wall. Task 2 included implementation of the selected materials and validated design models during combustor preliminary design. Detail design of the selected combustor concept and its refinement with 3D aerothermal analysis were completed in Task 3. Task 4 covered detail drawings, process development and fabrication, and a series of burner rig tests. The purpose of this paper is to provide details of the investigation into the fundamental flow and heat transfer characteristics of the CMC wall structure as well as implementation of the fundamental analysis method for full-scale combustor design.

Production technology for high efficiency ion implanted solar cells

NASA Technical Reports Server (NTRS)

Kirkpatrick, A. R.; Minnucci, J. A.; Greenwald, A. C.; Josephs, R. H.

1978-01-01

Ion implantation is being developed for high volume automated production of silicon solar cells. An implanter designed for solar cell processing and able to properly implant up to 300 4-inch wafers per hour is now operational. A machine to implant 180 sq m/hr of solar cell material has been designed. Implanted silicon solar cells with efficiencies exceeding 16% AM1 are now being produced and higher efficiencies are expected. Ion implantation and transient processing by pulsed electron beams are being integrated with electrostatic bonding to accomplish a simple method for large scale, low cost production of high efficiency solar cell arrays.

Design method of high-efficient 
LED headlamp lens.

PubMed

Chen, Fei; Wang, Kai; Qin, Zong; Wu, Dan; Luo, Xiaobing; Liu, Sheng

2010-09-27

Low optical efficiency of light-emitting diode (LED) based headlamp is one of the most important issues to obstruct applications of LEDs in headlamp. An effective high-efficient LED headlamp freeform lens design method is introduced in this paper. A low-beam lens and a high-beam lens for LED headlamp are designed according to this method. Monte Carlo ray tracing simulation results demonstrate that the LED headlamp with these two lenses can fully comply with the ECE regulation without any other lens or reflector. Moreover, optical efficiencies of both these two lenses are more than 88% in theory.

High efficiency silicon solar cell based on asymmetric nanowire.

PubMed

Ko, Myung-Dong; Rim, Taiuk; Kim, Kihyun; Meyyappan, M; Baek, Chang-Ki

2015-07-08

Improving the efficiency of solar cells through novel materials and devices is critical to realize the full potential of solar energy to meet the growing worldwide energy demands. We present here a highly efficient radial p-n junction silicon solar cell using an asymmetric nanowire structure with a shorter bottom core diameter than at the top. A maximum short circuit current density of 27.5 mA/cm(2) and an efficiency of 7.53% were realized without anti-reflection coating. Changing the silicon nanowire (SiNW) structure from conventional symmetric to asymmetric nature improves the efficiency due to increased short circuit current density. From numerical simulation and measurement of the optical characteristics, the total reflection on the sidewalls is seen to increase the light trapping path and charge carrier generation in the radial junction of the asymmetric SiNW, yielding high external quantum efficiency and short circuit current density. The proposed asymmetric structure has great potential to effectively improve the efficiency of the SiNW solar cells.

High Performance Computing Meets Energy Efficiency - Continuum Magazine |

Science.gov Websites

NREL High Performance Computing Meets Energy Efficiency High Performance Computing Meets Energy turbines. Simulation by Patrick J. Moriarty and Matthew J. Churchfield, NREL The new High Performance Computing Data Center at the National Renewable Energy Laboratory (NREL) hosts high-speed, high-volume data

Development of high-efficiency solar cells on silicon web

NASA Technical Reports Server (NTRS)

Rohatgi, A.; Meier, D. L.; Campbell, R. B.; Seidensticker, R. G.; Rai-Choudhury, P.

1985-01-01

High-efficiency dendritic cells were discussed. The influence of twin planes and heat treatment on the location and effect of trace impurities was of particular interest. Proper heat treatment often increases efficiency by causing impurities to pile up at twin planes. Oxide passivation had a beneficial effect on efficiency. A very efficient antireflective (AR) coating of zinc selenide and magnesium fluoride was designed and fabricated. An aluminum back-surface reflector was also effective.

High-Efficiency Hall Thruster Discharge Power Converter

NASA Technical Reports Server (NTRS)

Jaquish, Thomas

2015-01-01

Busek Company, Inc., is designing, building, and testing a new printed circuit board converter. The new converter consists of two series or parallel boards (slices) intended to power a high-voltage Hall accelerator (HiVHAC) thruster or other similarly sized electric propulsion devices. The converter accepts 80- to 160-V input and generates 200- to 700-V isolated output while delivering continually adjustable 300-W to 3.5-kW power. Busek built and demonstrated one board that achieved nearly 94 percent efficiency the first time it was turned on, with projected efficiency exceeding 97 percent following timing software optimization. The board has a projected specific mass of 1.2 kg/kW, achieved through high-frequency switching. In Phase II, Busek optimized to exceed 97 percent efficiency and built a second prototype in a form factor more appropriate for flight. This converter then was integrated with a set of upgraded existing boards for powering magnets and the cathode. The program culminated with integrating the entire power processing unit and testing it on a Busek thruster and on NASA's HiVHAC thruster.

High-efficiency 20 GHz traveling wave tube development for space communications

NASA Technical Reports Server (NTRS)

Aldana, S. L.; Tamashiro, R. N.

1991-01-01

A 75 watt CW high efficiency helix TWT operating at 20 GHz was developed for satellite communication systems. The purpose was to extend the performance capabilities of helix TWTs by using recent technology developments. The TWT described is a unique design because high overall efficiency is obtained with a low perveance beam. In the past, low perveance designs resulted in low beam efficiencies. However, due to recent breakthoughs in diamond rod technology and in collector electrode materials, high efficiencies can now be achieved with low perveance beams. The advantage of a low perveance beam is a reduction in space charge within the beam which translates to more efficient collector operation. In addition, this design incorporates textured graphite electrodes which further enhance collector operation by suppressing backstreaming secondaries. The diamond supported helix circuit features low RF losses, high interaction impedance, good thermal handling capability and has been designed to compensate for the low perveance beam. One more discussed tube feature is the use of a velocity taper in the output helix that achieves low signal distortion while maintaining high efficiency.

Loss mechanisms in high-efficiency solar cells: Study of material properties and high-efficiency solar-cell performance on material composition: Project tasks

NASA Technical Reports Server (NTRS)

Sah, C. T.

1985-01-01

Loss mechanisms in high-efficiency solar cells were discussed. Fundamental limitations and practical solutions were stressed. Present cell efficiency is limited by many recombination sites: emitter, base, contacts, and oxide/silicon interface. Use of polysilicon passivation was suggested. After reduction of these losses, a 25% efficient cell could be built. A floating emitter cell design was shown that had the potential of low recombination losses.

The High-Repetition-Rate Advanced Petawatt Laser System

DOE Office of Scientific and Technical Information (OSTI.GOV)

Haefner, Constantin; Jarboe, Jeff; Koubikova, Luci

2017-02-02

The High-Repetition-Rate Advanced Petawatt Laser System (HAPLS), being developed at Lawrence Livermore National Laboratory (LLNL), recently completed a significant milestone: demonstration of continuous operation of an all diode-pumped, high-energy femtosecond petawatt laser system. The system is now ready for delivery and integration at the European Extreme Light Infrastructure Beamlines facility project (ELI Beamlines) in the Czech Republic.

Advanced energy system program

NASA Astrophysics Data System (ADS)

Trester, K.

1989-02-01

The objectives of the program are to design, develop and demonstrate a natural-gas-fueled, highly recuperated, 50 kW Brayton-cycle cogeneration system for commercial, institutional, and multifamily residential applications. Marketing studies have shown that this Advanced Energy System (AES), with its many unique and cost-effective features, has the potential to offer significant reductions in annual electrical and thermal energy costs to the consumer. Specific advantages of the system that result in low cost of ownership are high electrical efficiency (30 percent, HHV), low maintenance, high reliability and long life (20 years).

High-resolution high-efficiency multilayer Fresnel zone plates for soft and hard x-rays

NASA Astrophysics Data System (ADS)

Sanli, Umut T.; Keskinbora, Kahraman; Gregorczyk, Keith; Leister, Jonas; Teeny, Nicolas; Grévent, Corinne; Knez, Mato; Schütz, Gisela

2015-09-01

X-ray microscopy enables high spatial resolutions, high penetration depths and characterization of a broad range of materials. Calculations show that nanometer range resolution is achievable in the hard X-ray regime by using Fresnel zone plates (FZPs) if certain conditions are satisfied. However, this requires, among other things, aspect ratios of several thousands. The multilayer (ML) type FZPs, having virtually unlimited aspect ratios, are strong candidates to achieve single nanometer resolutions. Our research is focused on the fabrication of ML-FZPs which encompasses deposition of multilayers over a glass fiber via the atomic layer deposition (ALD), which is subsequently sliced in the optimum thickness for the X-ray energy by a focused ion beam (FIB). We recently achieved aberration free imaging by resolving 21 nm features with an efficiency of up to 12.5 %, the highest imaging resolution achieved by an ML-FZP. We also showed efficient focusing of 7.9 keV X-rays down to 30 nm focal spot size (FWHM). For resolutions below ~10 nm, efficiencies would decrease significantly due to wave coupling effects. To compensate this effect high efficiency, low stress materials have to be researched, as lower intrinsic stresses will allow fabrication of larger FZPs with higher number of zones, leading to high light intensity at the focus. As a first step we fabricated an ML-FZP with a diameter of 62 μm, an outermost zone width of 12 nm and 452 active zones. Further strategies for fabrication of high resolution high efficiency multilayer FZPs will also be discussed.

High Quantum Efficiency OLED Lighting Systems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shiang, Joseph

The overall goal of the program was to apply improvements in light outcoupling technology to a practical large area plastic luminaire, and thus enable the product vision of an extremely thin form factor high efficiency large area light source. The target substrate was plastic and the baseline device was operating at 35 LPW at the start of the program. The target LPW of the program was a >2x improvement in the LPW efficacy and the overall amount of light to be delivered was relatively high 900 lumens. Despite the extremely difficult challenges associated with scaling up a wet solution processmore » on plastic substrates, the program was able to make substantial progress. A small molecule wet solution process was successfully implemented on plastic substrates with almost no loss in efficiency in transitioning from the laboratory scale glass to large area plastic substrates. By transitioning to a small molecule based process, the LPW entitlement increased from 35 LPW to 60 LPW. A further 10% improvement in outcoupling efficiency was demonstrated via the use of a highly reflecting cathode, which reduced absorptive loss in the OLED device. The calculated potential improvement in some cases is even larger, ~30%, and thus there is considerable room for optimism in improving the net light coupling efficacy, provided absorptive loss mechanisms are eliminated. Further improvements are possible if scattering schemes such as the silver nanowire based hard coat structure are fully developed. The wet coating processes were successfully scaled to large area plastic substrate and resulted in the construction of a 900 lumens luminaire device.« less

High-efficiency GaAs concentrator space cells

NASA Technical Reports Server (NTRS)

Werthen, J. G.; Virshup, G. F.; Macmillan, H. F.; Ford, C. W.; Hamaker, H. C.

1987-01-01

High efficiency Al sub x Ga sub 1-x As/GaAs heteroface solar concentrator cells have been developed for space applications. The cells, which were grown using metalorganic chemical vapor deposition (MOCVD), have been fabricated in both the p-n and n-p configurations. Magnesium and zinc are used as the p-type dopants, and Se is used as the n-type dopant. The space cells, which are designed for use in a Cassegrainian concentrator operating at 100 suns, AMO, have a circular illuminated area 4 mm in diameter on a 5 mm by 5 mm cell. These cells have exhibited flash-tested efficiencies as high as 23.6 percent at 28 C and 21.6 percent at 80 C.

Development of high-efficiency solar cells on silicon web

NASA Technical Reports Server (NTRS)

Meier, D. L.; Greggi, J.; Okeeffe, T. W.; Rai-Choudhury, P.

1986-01-01

Work was performed to improve web base material with a goal of obtaining solar cell efficiencies in excess of 18% (AM1). Efforts in this program are directed toward identifying carrier loss mechanisms in web silicon, eliminating or reducing these mechanisms, designing a high efficiency cell structure with the aid of numerical models, and fabricating high efficiency web solar cells. Fabrication techniques must preserve or enhance carrier lifetime in the bulk of the cell and minimize recombination of carriers at the external surfaces. Three completed cells were viewed by cross-sectional transmission electron microscopy (TEM) in order to investigate further the relation between structural defects and electrical performance of web cells. Consistent with past TEM examinations, the cell with the highest efficiency (15.0%) had no dislocations but did have 11 twin planes.

High-efficiency solar cell and method for fabrication

DOEpatents

Hou, H.Q.; Reinhardt, K.C.

1999-08-31

A high-efficiency 3- or 4-junction solar cell is disclosed with a theoretical AM0 energy conversion efficiency of about 40%. The solar cell includes p-n junctions formed from indium gallium arsenide nitride (InGaAsN), gallium arsenide (GaAs) and indium gallium aluminum phosphide (InGaAlP) separated by n-p tunnel junctions. An optional germanium (Ge) p-n junction can be formed in the substrate upon which the other p-n junctions are grown. The bandgap energies for each p-n junction are tailored to provide substantially equal short-circuit currents for each p-n junction, thereby eliminating current bottlenecks and improving the overall energy conversion efficiency of the solar cell. Additionally, the use of an InGaAsN p-n junction overcomes super-bandgap energy losses that are present in conventional multi-junction solar cells. A method is also disclosed for fabricating the high-efficiency 3- or 4-junction solar cell by metal-organic chemical vapor deposition (MOCVD). 4 figs.

Advanced IGCC/Hydrogen Gas Turbine Development

DOE Office of Scientific and Technical Information (OSTI.GOV)

York, William; Hughes, Michael; Berry, Jonathan

2015-07-30

The objective of this program was to develop the technologies required for a fuel flexible (coal derived hydrogen or syngas) gas turbine for IGCC that met DOE turbine performance goals. The overall DOE Advanced Power System goal was to conduct the research and development (R&D) necessary to produce coal-based IGCC power systems with high efficiency, near-zero emissions, and competitive capital cost. To meet this goal, the DOE Fossil Energy Turbine Program had as an interim objective of 2 to 3 percentage points improvement in combined cycle (CC) efficiency. The final goal is 3 to 5 percentage points improvement in CCmore » efficiency above the state of the art for CC turbines in IGCC applications at the time the program started. The efficiency goals were for NOx emissions of less than 2 ppm NOx (@15 % O2). As a result of the technologies developed under this program, the DOE goals were exceeded with a projected 8 point efficiency improvement. In addition, a new combustion technology was conceived of and developed to overcome the challenges of burning hydrogen and achieving the DOE’s NOx goal. This report also covers the developments under the ARRA-funded portion of the program that include gas turbine technology advancements for improvement in the efficiency, emissions, and cost performance of gas turbines for industrial applications with carbon capture and sequestration. Example applications could be cement plants, chemical plants, refineries, steel and aluminum plants, manufacturing facilities, etc. The DOE’s goal for more than 5 percentage point improvement in efficiency was met with cycle analyses performed for representative IGCC Steel Mill and IGCC Refinery applications. Technologies were developed in this program under the following areas: combustion, larger latter stage buckets, CMC and EBC, advanced materials and coatings, advanced configurations to reduce cooling, sealing and rotor purge flows, turbine aerodynamics, advanced sensors, advancements in

High extraction efficiency ultraviolet light-emitting diode

DOEpatents

Wierer, Jonathan; Montano, Ines; Allerman, Andrew A.

2015-11-24

Ultraviolet light-emitting diodes with tailored AlGaN quantum wells can achieve high extraction efficiency. For efficient bottom light extraction, parallel polarized light is preferred, because it propagates predominately perpendicular to the QW plane and into the typical and more efficient light escape cones. This is favored over perpendicular polarized light that propagates along the QW plane which requires multiple, lossy bounces before extraction. The thickness and carrier density of AlGaN QW layers have a strong influence on the valence subband structure, and the resulting optical polarization and light extraction of ultraviolet light-emitting diodes. At Al>0.3, thinner QW layers (<2.5 nm are preferred) result in light preferentially polarized parallel to the QW plane. Also, active regions consisting of six or more QWs, to reduce carrier density, and with thin barriers, to efficiently inject carriers in all the QWs, are preferred.

Modern energy efficient technologies of high-rise construction

NASA Astrophysics Data System (ADS)

Lukmanova, Inessa; Golov, Roman

2018-03-01

The paper analyzes modern energy-efficient technologies, both being applied, and only introduced into the application in the construction of high-rise residential buildings. All technologies are systematized by the authors as part of a unified model of "Arrows of Energy-Efficient Technologies", which imply performing energy-saving measures in the design, construction and operation of buildings.

High Efficiency Solar Integrated Roof Membrane Product

DOE Office of Scientific and Technical Information (OSTI.GOV)

Partyka, Eric; Shenoy, Anil

2013-05-15

This project was designed to address the Solar Energy Technology Program objective, to develop new methods to integrate photovoltaic (PV) cells or modules within a building-integrated photovoltaic (BIPV) application that will result in lower installed cost as well as higher efficiencies of the encapsulated/embedded PV module. The technology assessment and development focused on the evaluation and identification of manufacturing technologies and equipment capable of producing such low-cost, high-efficiency, flexible BIPV solar cells on single-ply roofing membranes.

High bandgap III-V alloys for high efficiency optoelectronics

DOEpatents

Alberi, Kirstin; Mascarenhas, Angelo; Wanlass, Mark

2017-01-10

High bandgap alloys for high efficiency optoelectronics are disclosed. An exemplary optoelectronic device may include a substrate, at least one Al.sub.1-xIn.sub.xP layer, and a step-grade buffer between the substrate and at least one Al.sub.1-xIn.sub.xP layer. The buffer may begin with a layer that is substantially lattice matched to GaAs, and may then incrementally increase the lattice constant in each sequential layer until a predetermined lattice constant of Al.sub.1-xIn.sub.xP is reached.

Fundamental Materials Studies for Advanced High Power Microwave and Terahertz Vacuum Electronic Radiation Sources

DTIC Science & Technology

2014-12-10

AFRL-OSR-VA-TR-2014-0359 Fundamental Materials Studies for Advanced High Power Microwave and Terahertz John Booske UNIVERSITY OF WISCONSIN SYSTEM...12-2014 Final Technical Performance Report October 1, 2011 - September 30, 2014 Fundamental Materials Studies for Advanced High Power Microwave and...emission-barrier scandate cathodes and identify related, alternative cathode materials systems for advanced vacuum electronic cathodes for high power THz

High-efficiency machining methods for aviation materials

NASA Astrophysics Data System (ADS)

Kononov, V. K.

1991-07-01

The papers contained in this volume present results of theoretical and experimental studies aimed at increasing the efficiency of cutting tools during the machining of high-temperature materials and titanium alloys. Specific topics discussed include a study of the performance of disk cutters during the machining of flexible parts of a high-temperature alloy, VZhL14N; a study of the wear resistance of cutters of hard alloys of various types; effect of a deformed electric field on the precision of the electrochemical machining of gas turbine engine components; and efficient machining of parts of composite materials. The discussion also covers the effect of the technological process structure on the residual stress distribution in the blades of gas turbine engines; modeling of the multiparameter assembly of engineering products for a specified priority of geometrical output parameters; and a study of the quality of the surface and surface layer of specimens machined by a high-temperature pulsed plasma.

High-efficiency silicon solar-cell design and practical barriers

NASA Technical Reports Server (NTRS)

Mokashi, A.

1985-01-01

A numerical evaluation technique is used to study the impact of practical barriers, such as heavy doping effects (Auger recombination, band gap narrowing), surface recombination, shadowing losses and minority-carrier lifetime (Tau), on a high efficiency silicon solar cell performance. Considering a high Tau of 1 ms, efficiency of a silicon solar cell of the hypothetical case is estimated to be around 29%. This is comparable with (detailed balance limit) maximum efficiency of a p-n junction solar cell of 30%. Value of Tau is varied from 1 second to 20 micro. Heavy doping effects, and realizable values of surface recombination velocities and shadowing, are then considered in succession and their influence on cell efficiency is evaluated and quantified. These practical barriers cause the cell efficiency to reduce from the maximum value of 29% to the experimentally achieved value of about 19%. Improvement in open circuit voltage V sub oc is required to achieve cell efficiency greater than 20%. Increased value of Tau reduces reverse saturation current and, hence, improves V sub oc. Control of surface recombination losses becomes critical at higher V sub oc. Substantial improvement in Tau and considerable reduction in surface recombination velocities is essential to achieve cell efficiencies greater than 20%.

Highly Flexible and Efficient Solar Steam Generation Device.

PubMed

Chen, Chaoji; Li, Yiju; Song, Jianwei; Yang, Zhi; Kuang, Yudi; Hitz, Emily; Jia, Chao; Gong, Amy; Jiang, Feng; Zhu, J Y; Yang, Bao; Xie, Jia; Hu, Liangbing

2017-08-01

Solar steam generation with subsequent steam recondensation has been regarded as one of the most promising techniques to utilize the abundant solar energy and sea water or other unpurified water through water purification, desalination, and distillation. Although tremendous efforts have been dedicated to developing high-efficiency solar steam generation devices, challenges remain in terms of the relatively low efficiency, complicated fabrications, high cost, and inability to scale up. Here, inspired by the water transpiration behavior of trees, the use of carbon nanotube (CNT)-modified flexible wood membrane (F-Wood/CNTs) is demonstrated as a flexible, portable, recyclable, and efficient solar steam generation device for low-cost and scalable solar steam generation applications. Benefitting from the unique structural merits of the F-Wood/CNTs membrane-a black CNT-coated hair-like surface with excellent light absorbability, wood matrix with low thermal conductivity, hierarchical micro- and nanochannels for water pumping and escaping, solar steam generation device based on the F-Wood/CNTs membrane demonstrates a high efficiency of 81% at 10 kW cm -2 , representing one of the highest values ever-reported. The nature-inspired design concept in this study is straightforward and easily scalable, representing one of the most promising solutions for renewable and portable solar energy generation and other related phase-change applications. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Parallel high-performance grid computing: capabilities and opportunities of a novel demanding service and business class allowing highest resource efficiency.

PubMed

Kepper, Nick; Ettig, Ramona; Dickmann, Frank; Stehr, Rene; Grosveld, Frank G; Wedemann, Gero; Knoch, Tobias A

2010-01-01

Especially in the life-science and the health-care sectors the huge IT requirements are imminent due to the large and complex systems to be analysed and simulated. Grid infrastructures play here a rapidly increasing role for research, diagnostics, and treatment, since they provide the necessary large-scale resources efficiently. Whereas grids were first used for huge number crunching of trivially parallelizable problems, increasingly parallel high-performance computing is required. Here, we show for the prime example of molecular dynamic simulations how the presence of large grid clusters including very fast network interconnects within grid infrastructures allows now parallel high-performance grid computing efficiently and thus combines the benefits of dedicated super-computing centres and grid infrastructures. The demands for this service class are the highest since the user group has very heterogeneous requirements: i) two to many thousands of CPUs, ii) different memory architectures, iii) huge storage capabilities, and iv) fast communication via network interconnects, are all needed in different combinations and must be considered in a highly dedicated manner to reach highest performance efficiency. Beyond, advanced and dedicated i) interaction with users, ii) the management of jobs, iii) accounting, and iv) billing, not only combines classic with parallel high-performance grid usage, but more importantly is also able to increase the efficiency of IT resource providers. Consequently, the mere "yes-we-can" becomes a huge opportunity like e.g. the life-science and health-care sectors as well as grid infrastructures by reaching higher level of resource efficiency.

High Efficiency Heat Exchanger for High Temperature and High Pressure Applications

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sienicki, James J.; Lv, Qiuping; Moisseytsev, Anton

CompRex, LLC (CompRex) specializes in the design and manufacture of compact heat exchangers and heat exchange reactors for high temperature and high pressure applications. CompRex’s proprietary compact technology not only increases heat exchange efficiency by at least 25 % but also reduces footprint by at least a factor of ten compared to traditional shell-and-tube solutions of the same capacity and by 15 to 20 % compared to other currently available Printed Circuit Heat Exchanger (PCHE) solutions. As a result, CompRex’s solution is especially suitable for Brayton cycle supercritical carbon dioxide (sCO2) systems given its high efficiency and significantly lower capitalmore » and operating expenses. CompRex has already successfully demonstrated its technology and ability to deliver with a pilot-scale compact heat exchanger that was under contract by the Naval Nuclear Laboratory for sCO2 power cycle development. The performance tested unit met or exceeded the thermal and hydraulic specifications with measured heat transfer between 95 to 98 % of maximum heat transfer and temperature and pressure drop values all consistent with the modeled values. CompRex’s vision is to commercialize its compact technology and become the leading provider for compact heat exchangers and heat exchange reactors for various applications including Brayton cycle sCO2 systems. One of the limitations of the sCO2 Brayton power cycle is the design and manufacturing of efficient heat exchangers at extreme operating conditions. Current diffusion-bonded heat exchangers have limitations on the channel size through which the fluid travels, resulting in excessive solid material per heat exchanger volume. CompRex’s design allows for more open area and shorter fluid proximity for increased heat transfer efficiency while sustaining the structural integrity needed for the application. CompRex is developing a novel improvement to its current heat exchanger design where fluids are directed to

Creating an advance-care-planning decision aid for high-risk surgery: a qualitative study.

PubMed

Schuster, Anne Lr; Aslakson, Rebecca A; Bridges, John Fp

2014-01-01

High-risk surgery patients may lose decision-making capacity as a result of surgical complications. Advance care planning prior to surgery may be beneficial, but remains controversial and is hindered by a lack of appropriate decision aids. This study sought to examine stakeholders' views on the appropriateness of using decision aids, in general, to support advance care planning among high-risk surgery populations and the design of such a decision aid. Key informants were recruited through purposive and snowball sampling. Semi-structured interviews were conducted by phone until data collected reached theoretical saturation. Key informants were asked to discuss their thoughts about advance care planning and interventions to support advance care planning, particularly for this population. Researchers took de-identified notes that were analyzed for emerging concordant, discordant, and recurrent themes using interpretative phenomenological analysis. Key informants described the importance of initiating advance care planning preoperatively, despite potential challenges present in surgical settings. In general, decision aids were viewed as an appropriate approach to support advance care planning for this population. A recipe emerged from the data that outlines tools, ingredients, and tips for success that are needed to design an advance care planning decision aid for high-risk surgical settings. Stakeholders supported incorporating advance care planning in high-risk surgical settings and endorsed the appropriateness of using decision aids to do so. Findings will inform the next stages of developing the first advance care planning decision aid for high-risk surgery patients.

A pulse-compression-ring circuit for high-efficiency electric propulsion.

PubMed

Owens, Thomas L

2008-03-01

A highly efficient, highly reliable pulsed-power system has been developed for use in high power, repetitively pulsed inductive plasma thrusters. The pulsed inductive thruster ejects plasma propellant at a high velocity using a Lorentz force developed through inductive coupling to the plasma. Having greatly increased propellant-utilization efficiency compared to chemical rockets, this type of electric propulsion system may one day propel spacecraft on long-duration deep-space missions. High system reliability and electrical efficiency are extremely important for these extended missions. In the prototype pulsed-power system described here, exceptional reliability is achieved using a pulse-compression circuit driven by both active solid-state switching and passive magnetic switching. High efficiency is achieved using a novel ring architecture that recovers unused energy in a pulse-compression system with minimal circuit loss after each impulse. As an added benefit, voltage reversal is eliminated in the ring topology, resulting in long lifetimes for energy-storage capacitors. System tests were performed using an adjustable inductive load at a voltage level of 3.3 kV, a peak current of 20 kA, and a current switching rate of 15 kA/micros.

Overview of CMC Development Activities in NASA's Ultra-Efficient Engine Technology (UEET) Program

NASA Technical Reports Server (NTRS)

Brewer, Dave

2001-01-01

The primary objective of the UEET (Ultra-Efficient Engine Technology) Program is to address two of the most critical propulsion issues: performance/efficiency and reduced emissions. High performance, low emissions engine systems will lead to significant improvement in local air quality, minimum impact on ozone depletion and level to an overall reduction in aviation contribution to global warming. The Materials and Structures for High Performance project will develop and demonstrate advanced high temperature materials to enable high-performance, high efficiency, and environmentally compatible propulsion systems.

Advanced research and technology program for advanced high pressure oxygen-hydrogen rocket propulsion

NASA Technical Reports Server (NTRS)

Marsik, S. J.; Morea, S. F.

1985-01-01

A research and technology program for advanced high pressure, oxygen-hydrogen rocket propulsion technology is presently being pursued by the National Aeronautics and Space Administration (NASA) to establish the basic discipline technologies, develop the analytical tools, and establish the data base necessary for an orderly evolution of the staged combustion reusable rocket engine. The need for the program is based on the premise that the USA will depend on the Shuttle and its derivative versions as its principal Earth-to-orbit transportation system for the next 20 to 30 yr. The program is focused in three principal areas of enhancement: (1) life extension, (2) performance, and (3) operations and diagnosis. Within the technological disciplines the efforts include: rotordynamics, structural dynamics, fluid and gas dynamics, materials fatigue/fracture/life, turbomachinery fluid mechanics, ignition/combustion processes, manufacturing/producibility/nondestructive evaluation methods and materials development/evaluation. An overview of the Advanced High Pressure Oxygen-Hydrogen Rocket Propulsion Technology Program Structure and Working Groups objectives are presented with highlights of several significant achievements.

Advanced research and technology programs for advanced high-pressure oxygen-hydrogen rocket propulsion

NASA Technical Reports Server (NTRS)

Marsik, S. J.; Morea, S. F.

1985-01-01

A research and technology program for advanced high pressure, oxygen-hydrogen rocket propulsion technology is presently being pursued by the National Aeronautics and Space Administration (NASA) to establish the basic discipline technologies, develop the analytical tools, and establish the data base necessary for an orderly evolution of the staged combustion reusable rocket engine. The need for the program is based on the premise that the USA will depend on the Shuttle and its derivative versions as its principal Earth-to-orbit transportation system for the next 20 to 30 yr. The program is focused in three principal areas of enhancement: (1) life extension, (2) performance, and (3) operations and diagnosis. Within the technological disciplines the efforts include: rotordynamics, structural dynamics, fluid and gas dynamics, materials fatigue/fracture/life, turbomachinery fluid mechanics, ignition/combustion processes, manufacturing/producibility/nondestructive evaluation methods and materials development/evaluation. An overview of the Advanced High Pressure Oxygen-Hydrogen Rocket Propulsion Technology Program Structure and Working Groups objectives are presented with highlights of several significant achievements.

Advanced research and technology programs for advanced high-pressure oxygen-hydrogen rocket propulsion

NASA Astrophysics Data System (ADS)

Marsik, S. J.; Morea, S. F.

1985-03-01

A research and technology program for advanced high pressure, oxygen-hydrogen rocket propulsion technology is presently being pursued by the National Aeronautics and Space Administration (NASA) to establish the basic discipline technologies, develop the analytical tools, and establish the data base necessary for an orderly evolution of the staged combustion reusable rocket engine. The need for the program is based on the premise that the USA will depend on the Shuttle and its derivative versions as its principal Earth-to-orbit transportation system for the next 20 to 30 yr. The program is focused in three principal areas of enhancement: (1) life extension, (2) performance, and (3) operations and diagnosis. Within the technological disciplines the efforts include: rotordynamics, structural dynamics, fluid and gas dynamics, materials fatigue/fracture/life, turbomachinery fluid mechanics, ignition/combustion processes, manufacturing/producibility/nondestructive evaluation methods and materials development/evaluation. An overview of the Advanced High Pressure Oxygen-Hydrogen Rocket Propulsion Technology Program Structure and Working Groups objectives are presented with highlights of several significant achievements.

Performance characterization of high quantum efficiency metal package photomultiplier tubes for time-of-flight and high-resolution PET applications.

PubMed

Ko, Guen Bae; Lee, Jae Sung

2015-01-01

Metal package photomultiplier tubes (PMTs) with a metal channel dynode structure have several advanced features for devising such time-of-flight (TOF) and high spatial resolution positron emission tomography (PET) detectors, thanks to their high packing density, large effective area ratio, fast time response, and position encoding capability. Here, we report on an investigation of new metal package PMTs with high quantum efficiency (QE) for high-resolution PET and TOF PET detector modules. The latest metal package PMT, the Hamamatsu R11265 series, is served with two kinds of photocathodes that have higher quantum efficiency than normal bialkali (typical QE ≈ 25%), super bialkali (SBA; QE ≈ 35%), and ultra bialkali (UBA; QE ≈ 43%). In this study, the authors evaluated the performance of the new PMTs with SBA and UBA photocathodes as a PET detector by coupling various crystal arrays. They also investigated the performance improvements of high QE, focusing in particular on a block detector coupled with a lutetium-based scintillator. A single 4 × 4 × 10 mm(3) LYSO, a 7 × 7 array of 3 × 3 × 20 mm(3) LGSO, a 9 × 9 array of 1.2 × 1.2 × 10 mm(3) LYSO, and a 6 × 6 array of 1.5 × 1.5 × 7 mm(3) LuYAP were used for evaluation. All coincidence data were acquired with a DRS4 based fast digitizer. This new PMT shows promising crystal positioning accuracy, energy and time discrimination performance for TOF, and high-resolution PET applications. The authors also found that a metal channel PMT with SBA was enough for both TOF and high-resolution application, although UBA gave a minor improvement to time resolution. However, significant performance improvement was observed in relative low light output crystals (LuYAP) coupled with UBA. The results of this study will be of value as a useful reference to select PMTs for high-performance PET detectors.

Review of status developments of high-efficiency crystalline silicon solar cells

NASA Astrophysics Data System (ADS)

Liu, Jingjing; Yao, Yao; Xiao, Shaoqing; Gu, Xiaofeng

2018-03-01

In order to further improve cell efficiency and reduce cost in achieving grid parity, a large number of PV manufacturing companies, universities and research institutes have been devoted to a variety of low-cost and high-efficiency crystalline Si solar cells. In this article, the cell structures, characteristics and efficiency progresses of several types of high-efficiency crystalline Si solar cells that have been in small scale production or are promising in mass production are presented, including passivated emitter rear cell, tunnel oxide passivated contact solar cell, interdigitated back contact cell, heterojunction with intrinsic thin-layer cell, and heterojunction solar cells with interdigitated back contacts. Both the industrialization status and future development trend of high-efficiency crystalline silicon solar cells are also pinpointed.

Efficient High-Pressure State Equations

NASA Technical Reports Server (NTRS)

Harstad, Kenneth G.; Miller, Richard S.; Bellan, Josette

1997-01-01

A method is presented for a relatively accurate, noniterative, computationally efficient calculation of high-pressure fluid-mixture equations of state, especially targeted to gas turbines and rocket engines. Pressures above I bar and temperatures above 100 K are addressed The method is based on curve fitting an effective reference state relative to departure functions formed using the Peng-Robinson cubic state equation Fit parameters for H2, O2, N2, propane, methane, n-heptane, and methanol are given.

Highly Efficient, All-Dielectric Huygens Metasurfaces

NASA Astrophysics Data System (ADS)

Ollanik, Adam; Farrar-Foley, Nick; Smith, Jake; Escarra, Matthew

Demonstration of the control of light by the introduction of abrupt phase discontinuities across a subwavelength scale has opened the doors to a new level of wavefront control. All-dielectric Huygens metasurfaces hold significant promise due to their dramatically improved efficiency over plasmonic approaches. We present the successful design, computational modeling, and experimental realization of all-dielectric transmissive Huygens metasurfaces capable of deflection efficiency >90%. Dielectric Huygens sources, taking advantage of spectrally aligned electric and magnetic dipole resonances, are capable of tunable phase delay for transmitted light with near unity efficiency of forward scattering. Using ellipsoidal cylinder nanoantennas, we are able to manipulate the phase response and engineer a metasurface with a spatially gradient phase profile. Through careful design and optimization we mitigate the effects of inter-antenna coupling. We have designed and modeled metasurfaces demonstrating anomalous refraction with very high efficiency (>80%) for wavelength bands from the UV to the near-IR. These surfaces were designed using three distinct nanoantenna materials, Si, TiO2, and GaP, to demonstrate the flexibility of the technique. Experimentally, Si nanoantennas are fabricated using a combination of electron beam lithography and ICP/RIE-etching. Metasurfaces are characterized using a goniospectrometer capable of mapping light intensity on a cylindrical shell surrounding the metasurface.

Gas-phase advanced oxidation for effective, efficient in situ control of pollution.

PubMed

Johnson, Matthew S; Nilsson, Elna J K; Svensson, Erik A; Langer, Sarka

2014-01-01

In this article, gas-phase advanced oxidation, a new method for pollution control building on the photo-oxidation and particle formation chemistry occurring in the atmosphere, is introduced and characterized. The process uses ozone and UV-C light to produce in situ radicals to oxidize pollution, generating particles that are removed by a filter; ozone is removed using a MnO2 honeycomb catalyst. This combination of in situ processes removes a wide range of pollutants with a comparatively low specific energy input. Two proof-of-concept devices were built to test and optimize the process. The laboratory prototype was built of standard ventilation duct and could treat up to 850 m(3)/h. A portable continuous-flow prototype built in an aluminum flight case was able to treat 46 m(3)/h. Removal efficiencies of >95% were observed for propane, cyclohexane, benzene, isoprene, aerosol particle mass, and ozone for concentrations in the range of 0.4-6 ppm and exposure times up to 0.5 min. The laboratory prototype generated a OH(•) concentration derived from propane reaction of (2.5 ± 0.3) × 10(10) cm(-3) at a specific energy input of 3 kJ/m(3), and the portable device generated (4.6 ± 0.4) × 10(9) cm(-3) at 10 kJ/m(3). Based on these results, in situ gas-phase advanced oxidation is a viable control strategy for most volatile organic compounds, specifically those with a OH(•) reaction rate higher than ca. 5 × 10(-13) cm(3)/s. Gas-phase advanced oxidation is able to remove compounds that react with OH and to control ozone and total particulate mass. Secondary pollution including formaldehyde and ultrafine particles might be generated, depending on the composition of the primary pollution.

14 CFR 101.25 - Operating limitations for Class 2-High Power Rockets and Class 3-Advanced High Power Rockets.

Code of Federal Regulations, 2013 CFR

2013-01-01

... Power Rockets and Class 3-Advanced High Power Rockets. 101.25 Section 101.25 Aeronautics and Space... OPERATING RULES MOORED BALLOONS, KITES, AMATEUR ROCKETS AND UNMANNED FREE BALLOONS Amateur Rockets § 101.25 Operating limitations for Class 2-High Power Rockets and Class 3-Advanced High Power Rockets. When operating...

14 CFR 101.25 - Operating limitations for Class 2-High Power Rockets and Class 3-Advanced High Power Rockets.

Code of Federal Regulations, 2012 CFR

2012-01-01

... Power Rockets and Class 3-Advanced High Power Rockets. 101.25 Section 101.25 Aeronautics and Space... OPERATING RULES MOORED BALLOONS, KITES, AMATEUR ROCKETS AND UNMANNED FREE BALLOONS Amateur Rockets § 101.25 Operating limitations for Class 2-High Power Rockets and Class 3-Advanced High Power Rockets. When operating...

14 CFR 101.25 - Operating limitations for Class 2-High Power Rockets and Class 3-Advanced High Power Rockets.

Code of Federal Regulations, 2014 CFR

2014-01-01

... Power Rockets and Class 3-Advanced High Power Rockets. 101.25 Section 101.25 Aeronautics and Space... OPERATING RULES MOORED BALLOONS, KITES, AMATEUR ROCKETS AND UNMANNED FREE BALLOONS Amateur Rockets § 101.25 Operating limitations for Class 2-High Power Rockets and Class 3-Advanced High Power Rockets. When operating...

14 CFR 101.25 - Operating limitations for Class 2-High Power Rockets and Class 3-Advanced High Power Rockets.

Code of Federal Regulations, 2010 CFR

2010-01-01

... Power Rockets and Class 3-Advanced High Power Rockets. 101.25 Section 101.25 Aeronautics and Space... OPERATING RULES MOORED BALLOONS, KITES, AMATEUR ROCKETS AND UNMANNED FREE BALLOONS Amateur Rockets § 101.25 Operating limitations for Class 2-High Power Rockets and Class 3-Advanced High Power Rockets. When operating...

14 CFR 101.25 - Operating limitations for Class 2-High Power Rockets and Class 3-Advanced High Power Rockets.

Code of Federal Regulations, 2011 CFR

2011-01-01

... Power Rockets and Class 3-Advanced High Power Rockets. 101.25 Section 101.25 Aeronautics and Space... OPERATING RULES MOORED BALLOONS, KITES, AMATEUR ROCKETS AND UNMANNED FREE BALLOONS Amateur Rockets § 101.25 Operating limitations for Class 2-High Power Rockets and Class 3-Advanced High Power Rockets. When operating...

Advanced high-temperature batteries

NASA Technical Reports Server (NTRS)

Nelson, Paul A.

1989-01-01

The promise of very high specific energy and power was not yet achieved for practical battery systems. Some recent approaches are discussed for new approaches to achieving high performance for lithium/DeS2 cells and sodium/metal chloride cells. The main problems for the development of successful LiAl/FeS2 cells were the instability of the FeS2 electrode, which has resulted in rapidly declining capacity, the lack of an internal mechanism for accommodating overcharge of a cell, thus requiring the use of external charge control on each individual cell, and the lack of a suitable current collector for the positive electrode other than expensive molybdenum sheet material. Much progress was made in solving the first two problems. Reduction of the operating temperatures to 400 C by a change in electrolyte composition has increased the expected life to 1000 cycles. Also, a lithium shuttle mechanism was demonstrated for selected electrode compositions that permits sufficient overcharge tolerance to adjust for the normally expected cell-to-cell deviation in coulombic efficiency. Sodium/sulfur batteries and sodium/metal chloride batteries have demonstrated good reliability and long cycle life. For applications where very high power is desired, new electrolyte coinfigurations would be required. Design work was carried out for the sodium/metal chloride battery that demonstrates the feasibility of achieving high specific energy and high power for large battery cells having thin-walled high-surface area electrolytes.

FOREWORD: Focus on Advanced Ceramics Focus on Advanced Ceramics

NASA Astrophysics Data System (ADS)

Ohashi, Naoki

2011-06-01

Much research has been devoted recently to developing technologies for renewable energy and improving the efficiency of the processes and devices used in industry and everyday life. Efficient solutions have been found using novel materials such as platinum and palladium-based catalysts for car exhaust systems, samarium-cobalt and neodymium-iron-boron permanent magnets for electrical motors, and so on. However, their realization has resulted in an increasing demand for rare elements and in their deficit, the development of new materials based on more abundant elements and new functionalities of traditional materials. Moreover, increasing environmental and health concerns demand substitution of toxic or hazardous substances with nature-friendly alternatives. In this context, this focus issue on advanced ceramics aims to review current trends in ceramics science and technology. It is related to the International Conference on Science and Technology of Advanced Ceramics (STAC) held annually to discuss the emerging issues in the field of ceramics. An important direction of ceramic science is the collaboration between experimental and theoretical sciences. Recent developments in density functional theory and computer technology have enabled the prediction of physical and chemical properties of ceramics, thereby assisting the design of new materials. Therefore, this focus issue includes articles devoted to theory and advanced characterization techniques. As mentioned above, the potential shortage of rare elements is becoming critical to the industry and has resulted in a Japanese government initiative called the 'Ubiquitous Element Strategy'. This focus issue also includes articles related to this strategy and to the associated topics of energy conversion, such as phosphors for high-efficiency lighting and photocatalysts for solar-energy harvesting. We hope that this focus issue will provide a timely overview of current trends and problems in ceramics science and

Highly Efficient Amplifier for Ka-Band Communications

NASA Technical Reports Server (NTRS)

1996-01-01

An amplifier developed under a Small Business Innovation Research (SBIR) contract will have applications for both satellite and terrestrial communications. This power amplifier uses an innovative series bias arrangement of active devices to achieve over 40-percent efficiency at Ka-band frequencies with an output power of 0.66 W. The amplifier is fabricated on a 2.0- by 3.8-square millimeter chip through the use of Monolithic Microwave Integrated Circuit (MMIC) technology, and it uses state-of-the-art, Pseudomorphic High-Electron-Mobility Transistor (PHEMT) devices. Although the performance of the MMIC chip depends on these high-performance devices, the real innovations here are a unique series bias scheme, which results in a high-voltage chip supply, and careful design of the on-chip planar output stage combiner. This design concept has ramifications beyond the chip itself because it opens up the possibility of operation directly from a satellite power bus (usually 28 V) without a dc-dc converter. This will dramatically increase the overall system efficiency. Conventional microwave power amplifier designs utilize many devices all connected in parallel from the bias supply. This results in a low-bias voltage, typically 5 V, and a high bias current. With this configuration, substantial I(sup 2) R losses (current squared times resistance) may arise in the system bias-distribution network. By placing the devices in a series bias configuration, the total current is reduced, leading to reduced distribution losses. Careful design of the on-chip planar output stage power combiner is also important in minimizing losses. Using these concepts, a two-stage amplifier was designed for operation at 33 GHz and fabricated in a standard MMIC foundry process with 0.20-m PHEMT devices. Using a 20-V bias supply, the amplifier achieved efficiencies of over 40 percent with an output power of 0.66 W and a 16-dB gain over a 2-GHz bandwidth centered at 33 GHz. With a 28-V bias, a power

Highly efficient special sound absorbing solutions

NASA Technical Reports Server (NTRS)

Ionescu, M.; Petre-Lazar, S.

1974-01-01

Highly efficient special sound absorbing structures with the following criteria are considered: (1) A distribution surface of the sound absorbing material greater than that of the building element on which the structure is placed; (2) The highest possible absorption coefficient in the widest possible frequency band; and (3) adaptability to different construction and aesthetic conditions.

An advanced actuator for high-performance slewing

NASA Technical Reports Server (NTRS)

Downer, James; Eisenhaure, David; Hockney, Richard

1988-01-01

A conceptual design for an advanced momentum exchange actuator for application to spacecraft slewing is described. The particular concept is a magnetically-suspended, magnetically gimballed Control Moment Gyro (CMG). A scissored pair of these devices is sized to provide the torque and angular momentum capacity required to reorient a large spacecraft through large angle maneuvers. The concept described utilizes a composite material rotor to achieve the high momentum and energy densities to minimize system mass, an advanced superconducting magnetic suspension system to minimize system weight and power consumption. The magnetic suspension system is also capable of allowing for large angle gimballing of the rotor, thus eliminating the mass and reliability penalties attendant to conventional gimbals. Descriptions of the various subelement designs are included along with the necessary system sizing formulation and material.

Advanced Materials for High Temperature, High Performance, Wide Bandgap Power Modules

NASA Astrophysics Data System (ADS)

O'Neal, Chad B.; McGee, Brad; McPherson, Brice; Stabach, Jennifer; Lollar, Richard; Liederbach, Ross; Passmore, Brandon

2016-01-01

Advanced packaging materials must be utilized to take full advantage of the benefits of the superior electrical and thermal properties of wide bandgap power devices in the development of next generation power electronics systems. In this manuscript, the use of advanced materials for key packaging processes and components in multi-chip power modules will be discussed. For example, to date, there has been significant development in silver sintering paste as a high temperature die attach material replacement for conventional solder-based attach due to the improved thermal and mechanical characteristics as well as lower processing temperatures. In order to evaluate the bond quality and performance of this material, shear strength, thermal characteristics, and void quality for a number of silver sintering paste materials were analyzed as a die attach alternative to solder. In addition, as high voltage wide bandgap devices shift from engineering samples to commercial components, passivation materials become key in preventing premature breakdown in power modules. High temperature, high dielectric strength potting materials were investigated to be used to encapsulate and passivate components internal to a power module. The breakdown voltage up to 30 kV and corresponding leakage current for these materials as a function of temperature is also presented. Lastly, high temperature plastic housing materials are important for not only discrete devices but also for power modules. As the operational temperature of the device and/or ambient temperature increases, the mechanical strength and dielectric properties are dramatically reduced. Therefore, the electrical characteristics such as breakdown voltage and leakage current as a function of temperature for housing materials are presented.

Spectral efficiency in crosstalk-impaired multi-core fiber links

NASA Astrophysics Data System (ADS)

Luís, Ruben S.; Puttnam, Benjamin J.; Rademacher, Georg; Klaus, Werner; Agrell, Erik; Awaji, Yoshinari; Wada, Naoya

2018-02-01

We review the latest advances on ultra-high throughput transmission using crosstalk-limited single-mode multicore fibers and compare these with the theoretical spectral efficiency of such systems. We relate the crosstalkimposed spectral efficiency limits with fiber parameters, such as core diameter, core pitch, and trench design. Furthermore, we investigate the potential of techniques such as direction interleaving and high-order MIMO to improve the throughput or reach of these systems when using various modulation formats.

Highly efficient light management for perovskite solar cells

NASA Astrophysics Data System (ADS)

Wang, Dong-Lin; Cui, Hui-Juan; Hou, Guo-Jiao; Zhu, Zhen-Gang; Yan, Qing-Bo; Su, Gang

2016-01-01

Organic-inorganic halide perovskite solar cells have enormous potential to impact the existing photovoltaic industry. As realizing a higher conversion efficiency of the solar cell is still the most crucial task, a great number of schemes were proposed to minimize the carrier loss by optimizing the electrical properties of the perovskite solar cells. Here, we focus on another significant aspect that is to minimize the light loss by optimizing the light management to gain a high efficiency for perovskite solar cells. In our scheme, the slotted and inverted prism structured SiO2 layers are adopted to trap more light into the solar cells, and a better transparent conducting oxide layer is employed to reduce the parasitic absorption. For such an implementation, the efficiency and the serviceable angle of the perovskite solar cell can be promoted impressively. This proposal would shed new light on developing the high-performance perovskite solar cells.

Highly efficient light management for perovskite solar cells.

PubMed

Wang, Dong-Lin; Cui, Hui-Juan; Hou, Guo-Jiao; Zhu, Zhen-Gang; Yan, Qing-Bo; Su, Gang

2016-01-06

Organic-inorganic halide perovskite solar cells have enormous potential to impact the existing photovoltaic industry. As realizing a higher conversion efficiency of the solar cell is still the most crucial task, a great number of schemes were proposed to minimize the carrier loss by optimizing the electrical properties of the perovskite solar cells. Here, we focus on another significant aspect that is to minimize the light loss by optimizing the light management to gain a high efficiency for perovskite solar cells. In our scheme, the slotted and inverted prism structured SiO2 layers are adopted to trap more light into the solar cells, and a better transparent conducting oxide layer is employed to reduce the parasitic absorption. For such an implementation, the efficiency and the serviceable angle of the perovskite solar cell can be promoted impressively. This proposal would shed new light on developing the high-performance perovskite solar cells.

Efficient biprediction decision scheme for fast high efficiency video coding encoding

NASA Astrophysics Data System (ADS)

Park, Sang-hyo; Lee, Seung-ho; Jang, Euee S.; Jun, Dongsan; Kang, Jung-Won

2016-11-01

An efficient biprediction decision scheme of high efficiency video coding (HEVC) is proposed for fast-encoding applications. For low-delay video applications, bidirectional prediction can be used to increase compression performance efficiently with previous reference frames. However, at the same time, the computational complexity of the HEVC encoder is significantly increased due to the additional biprediction search. Although a some research has attempted to reduce this complexity, whether the prediction is strongly related to both motion complexity and prediction modes in a coding unit has not yet been investigated. A method that avoids most compression-inefficient search points is proposed so that the computational complexity of the motion estimation process can be dramatically decreased. To determine if biprediction is critical, the proposed method exploits the stochastic correlation of the context of prediction units (PUs): the direction of a PU and the accuracy of a motion vector. Through experimental results, the proposed method showed that the time complexity of biprediction can be reduced to 30% on average, outperforming existing methods in view of encoding time, number of function calls, and memory access.

Advanced Motor Drives Studies

NASA Technical Reports Server (NTRS)

Ehsani, M.; Tchamdjou, A.

1997-01-01

This report presents an evaluation of advanced motor drive systems as a replacement for the hydrazine fueled APU units. The replacement technology must meet several requirements which are particular to the space applications and the Orbiter in general. Some of these requirements are high efficiency, small size, high power density. In the first part of the study several motors are compared, based on their characteristics and in light of the Orbiter requirements. The best candidate, the brushless DC is chosen because of its particularly good performance with regards to efficiency. Several power electronics drive technologies including the conventional three-phase hard switched and several soft-switched inverters are then presented. In the last part of the study, a soft-switched inverter is analyzed and compared to its conventional hard-switched counterpart. Optimal efficiency is a basic requirement for space applications and the soft-switched technology represents an unavoidable trend for the future.

Advanced Solar Panel Designs

NASA Technical Reports Server (NTRS)

Ralph, E. L.; Linder, E. B.

1995-01-01

Solar panel designs that utilize new high-efficiency solar cells and lightweight rigid panel technologies are described. The resulting designs increase the specific power (W/kg) achievable in the near-term and are well suited to meet the demands of higher performance small satellites (smallsats). Advanced solar panel designs have been developed and demonstrated on two NASA SBIR contracts at Applied Solar. The first used 19% efficient, large area (5.5 cm x 6.5 cm) GaAs/Ge solar cells with a lightweight rigid graphite epoxy isogrid substrate configuration. A 1,445 sq cm coupon was fabricated and tested to demonstrate 60 W/kg with a high potential of achieving 80 W/kg. The second panel design used new 22% efficiency, dual-junction GaInP2/GaAs/Ge solar cells combined with a lightweight aluminum core/graphite fiber mesh facesheet substrate. A 1,445 sq cm coupon was fabricated and tested to demonstrate 105 W/kg with the potential of achieving 115 W/kg.

Ultra High Power and Efficiency Space Traveling-Wave Tube Amplifier Power Combiner with Reduced Size and Mass for NASA Missions

NASA Technical Reports Server (NTRS)

Simons, Rainee N.; Wintucky, Edwin G.; Wilson, Jeffrey D.; Force, Dale A.

2009-01-01

In the 2008 International Microwave Symposium (IMS) Digest version of our paper, recent advances in high power and efficiency space traveling-wave tube amplifiers (TWTAs) for NASA s space-to-Earth communications are presented. The RF power and efficiency of a new K-Band amplifier are 40 W and 50 percent and that of a new Ka-Band amplifier are 200 W and 60 percent. An important figure-of-merit, which is defined as the ratio of the RF power output to the mass (W/kg) of a TWT, has improved by a factor of ten over the previous generation Ka-Band devices. In this extended paper, a high power, high efficiency Ka-band combiner for multiple TWTs, based on a novel hybrid magic-T waveguide circuit design, is presented. The measured combiner efficiency is as high as 90 percent. In addition, at the design frequency of 32.05 GHz, error-free uncoded BPSK/QPSK data transmission at 8 megabits per second (Mbps), which is typical for deep space communications is demonstrated. Furthermore, QPSK data transmission at 622 Mbps is demonstrated with a low bit error rate of 2.4x10(exp -8), which exceeds the deep space state-of-the-art data rate transmission capability by more than two orders of magnitude. A potential application of the TWT combiner is in deep space communication systems for planetary exploration requiring transmitter power on the order of a kilowatt or higher.

Nitrogen Use Efficiency of California Almond Orchards Using Advanced Farming Practices

NASA Astrophysics Data System (ADS)

Smart, David; Schellenberg, Daniel; Saa Silva, Sebastian; Muhammad, Saiful; Sanden, Blake; Brown, Patrick

2014-05-01

Mobilization of reactive nitrogen species (NH3, NH4+, NOx, N2O, NO2- and NO3-) is perceived as one of the foremost challenges for modern agricultural production systems. Yet information to address the question of how advanced nitrogen (N) management alters reactive N mobilization is lacking. During 2009 to 2012 we monitored spatially constrained N2O emissions and potential leachable NO3-, along with yield-N content to examine their contribution to nitrogen use efficiency (NUE, fruit-N exported/fertilizer-N applied) for a modern, high yielding almond production system. This modern production system schedules irrigation to match evapotranspiration (ETc) estimated from the Penman-Montieth calculation of a reference evapotranspiration (ETo) times a seasonal crop coefficient (Kc) which was verified using eddy covariance and surface renewal latent heat flux estimates. Split N-fertilizer applications were targeted to tree-N demand and root proliferation. These production systems demand upwards of 300 kg N ha-1. NUE was found to be nearly 80% at an N application level allowing for economic sustainability of the system (308 kg N ha-1). When mobilization of N2O and NO3- were included in the NUE assessment, these systems were still highly sustainable in terms of N applied. We also monitored production and consumption of the greenhouse gases of carbon dioxide (CO2) and methane (CH4). These systems had relatively low levels of N2O emissions with emissions of N2O as a fraction of N-fertilizer applied being consistently less than IPCC Tier 1 emissions factors, and lower than the average estimated for most continental US farming systems. The system also demonstrated a capacity for net CH4 oxidation over the course of a season that occurred mainly in the driveways between tree rows that are kept dry over the course of the season in this arid environment. Our study indicated that tight management of water resources and targeted applications of N-fertilizer resulted in net positive

Ultra-bright and highly efficient inorganic based perovskite light-emitting diodes

PubMed Central

Zhang, Liuqi; Yang, Xiaolei; Jiang, Qi; Wang, Pengyang; Yin, Zhigang; Zhang, Xingwang; Tan, Hairen; Yang, Yang (Michael); Wei, Mingyang; Sutherland, Brandon R.; Sargent, Edward H.; You, Jingbi

2017-01-01

Inorganic perovskites such as CsPbX3 (X=Cl, Br, I) have attracted attention due to their excellent thermal stability and high photoluminescence quantum efficiency. However, the electroluminescence quantum efficiency of their light-emitting diodes was <1%. We posited that this low efficiency was a result of high leakage current caused by poor perovskite morphology, high non-radiative recombination at interfaces and perovskite grain boundaries, and also charge injection imbalance. Here, we incorporated a small amount of methylammonium organic cation into the CsPbBr3 lattice and by depositing a hydrophilic and insulating polyvinyl pyrrolidine polymer atop the ZnO electron-injection layer to overcome these issues. As a result, we obtained light-emitting diodes exhibiting a high brightness of 91,000 cd m−2 and a high external quantum efficiency of 10.4% using a mixed-cation perovskite Cs0.87MA0.13PbBr3 as the emitting layer. To the best of our knowledge, this is the brightest and most-efficient green perovskite light-emitting diodes reported to date. PMID:28589960

Metallic metasurfaces for high efficient polarization conversion control in transmission mode.

PubMed

Li, Tong; Hu, Xiaobin; Chen, Huamin; Zhao, Chen; Xu, Yun; Wei, Xin; Song, Guofeng

2017-10-02

A high efficient broadband polarization converter is an important component in integrated miniaturized optical systems, but its performances is often restricted by the material structures, metallic metasurfaces for polarization control in transmission mode never achieved efficiency above 0.5. Herein, we theoretically demonstrate that metallic metasurfaces constructed by thick cross-shaped particles can realize a high efficient polarization transformation over a broadband. We investigated the resonant properties of designed matesurfaces and found that the interaction between double FP cavity resonances and double bulk magnetic resonances is the main reason to generate a high transmissivity over a broadband. In addition, through using four resonances effect and tuning the anisotropic optical response, we realized a high efficient (> 0.85) quarter-wave plate at the wavelength range from 1175nm to 1310nm and a high efficient (> 0.9) half-wave plate at the wavelength range from 1130nm to 1230nm. The proposed polarization converters may have many potential applications in integrated polarization conversion devices and optical data storage systems.

Ultra-bright and highly efficient inorganic based perovskite light-emitting diodes

NASA Astrophysics Data System (ADS)

Zhang, Liuqi; Yang, Xiaolei; Jiang, Qi; Wang, Pengyang; Yin, Zhigang; Zhang, Xingwang; Tan, Hairen; Yang, Yang (Michael); Wei, Mingyang; Sutherland, Brandon R.; Sargent, Edward H.; You, Jingbi

2017-06-01

Inorganic perovskites such as CsPbX3 (X=Cl, Br, I) have attracted attention due to their excellent thermal stability and high photoluminescence quantum efficiency. However, the electroluminescence quantum efficiency of their light-emitting diodes was <1%. We posited that this low efficiency was a result of high leakage current caused by poor perovskite morphology, high non-radiative recombination at interfaces and perovskite grain boundaries, and also charge injection imbalance. Here, we incorporated a small amount of methylammonium organic cation into the CsPbBr3 lattice and by depositing a hydrophilic and insulating polyvinyl pyrrolidine polymer atop the ZnO electron-injection layer to overcome these issues. As a result, we obtained light-emitting diodes exhibiting a high brightness of 91,000 cd m-2 and a high external quantum efficiency of 10.4% using a mixed-cation perovskite Cs0.87MA0.13PbBr3 as the emitting layer. To the best of our knowledge, this is the brightest and most-efficient green perovskite light-emitting diodes reported to date.

Experiences of High-Achieving High School Students Who Have Taken Multiple Concurrent Advanced Placement Courses

ERIC Educational Resources Information Center

Milburn, Kristine M.

2011-01-01

Problem: An increasing number of high-achieving American high school students are enrolling in multiple Advanced Placement (AP) courses. As a result, high schools face a growing need to understand the impact of taking multiple AP courses concurrently on the social-emotional lives of high-achieving students. Procedures: This phenomenological…

High power, high efficiency, continuous-wave supercontinuum generation using standard telecom fibers.

PubMed

Arun, S; Choudhury, Vishal; Balaswamy, V; Prakash, Roopa; Supradeepa, V R

2018-04-02

We demonstrate a simple module for octave spanning continuous-wave supercontinuum generation using standard telecom fiber. This module can accept any high power ytterbium-doped fiber laser as input. The input light is transferred into the anomalous dispersion region of the telecom fiber through a cascade of Raman shifts. A recently proposed Raman laser architecture with distributed feedback efficiently performs these Raman conversions. A spectrum spanning over 1000nm (>1 octave) from 880 to 1900nm is demonstrated. The average power from the supercontinuum is ~34W with a high conversion efficiency of 44%. Input wavelength agility is demonstrated with similar supercontinua over a wide input wavelength range.

High power, high efficiency, continuous-wave supercontinuum generation using standard telecom fibers

NASA Astrophysics Data System (ADS)

Arun, S.; Choudhury, Vishal; Balaswamy, V.; Prakash, Roopa; Supradeepa, V. R.

2018-04-01

We demonstrate a simple module for octave spanning continuous-wave supercontinuum generation using standard telecom fiber. This module can accept any high power Ytterbium-doped fiber laser as input. The input light is transferred into the anomalous dispersion region of the telecom fiber through a cascade of Raman shifts. A recently proposed Raman laser architecture with distributed feedback efficiently performs these Raman conversions. A spectrum spanning over 1000nm(>1 octave) from 880-1900nm is demonstrated. The average power from the supercontinuum is ~34W with a high conversion efficiency of 44%. Input wavelength agility is demonstrated with similar supercontinua over a wide input wavelength range.

High efficiency blue and white phosphorescent organic light emitting devices

NASA Astrophysics Data System (ADS)

Eom, Sang-Hyun

Organic light-emitting devices (OLEDs) have important applications in full-color flat-panel displays and as solid-state lighting sources. Achieving high efficiency deep-blue phosphorescent OLEDs (PHOLEDs) is necessary for high performance full-color displays and white light sources with a high color rendering index (CRI); however it is more challenging compared to the longer wavelength light emissions such as green and red due to the higher energy excitations for the deep-blue emitter as well as the weak photopic response of deep-blue emission. This thesis details several effective strategies to enhancing efficiencies of deep-blue PHOLEDs based on iridium(III) bis(4',6'-difluorophenylpyridinato)tetrakis(1-pyrazolyl)borate (FIr6), which are further employed to demonstrate high efficiency white OLEDs by combining the deep-blue emitter with green and red emitters. First, we have employed 1,1-bis-(di-4-tolylaminophenyl) cyclohexane (TAPC) as the hole transporting material to enhance electron and triplet exciton confinement in Fir6-based PHOLEDs, which increased external quantum efficiency up to 18 %. Second, dual-emissive-layer (D-EML) structures consisting of an N,N -dicarbazolyl-3,5-benzene (mCP) layer doped with 4 wt % FIr6 and a p-bis (triphenylsilyly)benzene (UGH2) layer doped with 25 wt % FIr6 was employed to maximize exciton generation in the emissive layer. Combined with the p-i-n device structure, high power efficiencies of (25 +/- 2) lm/W at 100 cd/m2 and (20 +/- 2) lm/W at 1000 cd/m 2 were achieved. Moreover, the peak external quantum efficiency of (20 +/- 1) % was achieved by employing tris[3-(3-pyridyl)mesityl]borane (3TPYMB) as the electron transporting material, which further improves the exciton confinement in the emissive layer. With Cs2CO3 doping in the 3TPYMB layer to greatly increase its electrical conductivity, a peak power efficiency up to (36 +/- 2) lm/W from the deep-blue PHOLED was achieved, which also maintains Commission Internationale de L

LightAssembler: fast and memory-efficient assembly algorithm for high-throughput sequencing reads.

PubMed

El-Metwally, Sara; Zakaria, Magdi; Hamza, Taher

2016-11-01

The deluge of current sequenced data has exceeded Moore's Law, more than doubling every 2 years since the next-generation sequencing (NGS) technologies were invented. Accordingly, we will able to generate more and more data with high speed at fixed cost, but lack the computational resources to store, process and analyze it. With error prone high throughput NGS reads and genomic repeats, the assembly graph contains massive amount of redundant nodes and branching edges. Most assembly pipelines require this large graph to reside in memory to start their workflows, which is intractable for mammalian genomes. Resource-efficient genome assemblers combine both the power of advanced computing techniques and innovative data structures to encode the assembly graph efficiently in a computer memory. LightAssembler is a lightweight assembly algorithm designed to be executed on a desktop machine. It uses a pair of cache oblivious Bloom filters, one holding a uniform sample of [Formula: see text]-spaced sequenced [Formula: see text]-mers and the other holding [Formula: see text]-mers classified as likely correct, using a simple statistical test. LightAssembler contains a light implementation of the graph traversal and simplification modules that achieves comparable assembly accuracy and contiguity to other competing tools. Our method reduces the memory usage by [Formula: see text] compared to the resource-efficient assemblers using benchmark datasets from GAGE and Assemblathon projects. While LightAssembler can be considered as a gap-based sequence assembler, different gap sizes result in an almost constant assembly size and genome coverage. https://github.com/SaraEl-Metwally/LightAssembler CONTACT: sarah_almetwally4@mans.edu.egSupplementary information: Supplementary data are available at Bioinformatics online. © The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

Creating an advance-care-planning decision aid for high-risk surgery: a qualitative study

PubMed Central

2014-01-01

Background High-risk surgery patients may lose decision-making capacity as a result of surgical complications. Advance care planning prior to surgery may be beneficial, but remains controversial and is hindered by a lack of appropriate decision aids. This study sought to examine stakeholders’ views on the appropriateness of using decision aids, in general, to support advance care planning among high-risk surgery populations and the design of such a decision aid. Methods Key informants were recruited through purposive and snowball sampling. Semi-structured interviews were conducted by phone until data collected reached theoretical saturation. Key informants were asked to discuss their thoughts about advance care planning and interventions to support advance care planning, particularly for this population. Researchers took de-identified notes that were analyzed for emerging concordant, discordant, and recurrent themes using interpretative phenomenological analysis. Results Key informants described the importance of initiating advance care planning preoperatively, despite potential challenges present in surgical settings. In general, decision aids were viewed as an appropriate approach to support advance care planning for this population. A recipe emerged from the data that outlines tools, ingredients, and tips for success that are needed to design an advance care planning decision aid for high-risk surgical settings. Conclusions Stakeholders supported incorporating advance care planning in high-risk surgical settings and endorsed the appropriateness of using decision aids to do so. Findings will inform the next stages of developing the first advance care planning decision aid for high-risk surgery patients. PMID:25067908

Ku-band high efficiency GaAs MMIC power amplifiers

NASA Technical Reports Server (NTRS)

Tserng, H. Q.; Witkowski, L. C.; Wurtele, M.; Saunier, Paul

1988-01-01

The development of Ku-band high efficiency GaAs MMIC power amplifiers is examined. Three amplifier modules operating over the 13 to 15 GHz frequency range are to be developed. The first MMIC is a 1 W variable power amplifier (VPA) with 35 percent efficiency. On-chip digital gain control is to be provided. The second MMIC is a medium power amplifier (MPA) with an output power goal of 1 W and 40 percent power-added efficiency. The third MMIC is a high power amplifier (HPA) with 4 W output power goal and 40 percent power-added efficiency. An output power of 0.36 W/mm with 49 percent efficiency was obtained on an ion implanted single gate MESFET at 15 GHz. On a dual gate MESFET, an output power of 0.42 W/mm with 27 percent efficiency was obtained. A mask set was designed that includes single stage, two stage, and three stage single gate amplifiers. A single stage 600 micron amplifier produced 0.4 W/mm output power with 40 percent efficiency at 14 GHz. A four stage dual gate amplifier generated 500 mW of output power with 20 dB gain at 17 GHz. A four-bit digital-to-analog converter was designed and fabricated which has an output swing of -3 V to +/- 1 V.

Advances in Experiment Design for High Performance Aircraft

NASA Technical Reports Server (NTRS)

Morelli, Engene A.

1998-01-01

A general overview and summary of recent advances in experiment design for high performance aircraft is presented, along with results from flight tests. General theoretical background is included, with some discussion of various approaches to maneuver design. Flight test examples from the F-18 High Alpha Research Vehicle (HARV) are used to illustrate applications of the theory. Input forms are compared using Cramer-Rao bounds for the standard errors of estimated model parameters. Directions for future research in experiment design for high performance aircraft are identified.

Chemical beam epitaxy for high efficiency photovoltaic devices

NASA Technical Reports Server (NTRS)

Bensaoula, A.; Freundlich, A.; Vilela, M. F.; Medelci, N.; Renaud, P.

1994-01-01

InP-based multijunction tandem solar cells show great promise for the conversion efficiency (eta) and high radiation resistance. InP and its related ternary and quanternary compound semiconductors such as InGaAs and InGaAsP offer desirable combinations for energy bandgap values which are very suitable for multijunction tandem solar cell applications. The monolithically integrated InP/In(0.53)Ga(0.47)As tandem solar cells are expected to reach efficiencies above 30 percent. Wanlass, et.al., have reported AMO efficiencies as high as 20.1% for two terminal cells fabricated using atmospheric-pressure metalorganic vapor phase epitaxy (APMOVPE). The main limitations in their technique are first related to the degradation of the intercell ohmic contact (IOC), in this case the In(0.53)Ga(0.47)As tunnel junction during the growth of the top InP subcell structure, and second to the current matching, often limited by the In(0.53)Ga(0.47)As bottom subcell. Chemical beam epitaxy (CBE) has been shown to allow the growth of high quality materials with reproducible complex compositional and doping profiles. The main advantage of CBE compared to metalorganic chemical vapor deposition (MOCVD), the most popular technique for InP-based photovoltaic device fabrication, is the ability to grow high purity epilayers at much lower temperatures (450 C - 530 C). In a recent report it was shown that cost-wise CBE is a breakthrough technology for photovoltaic (PV) solar energy progress in the energy conversion efficiency of InP-based solar cells fabricated using chemical beam epitaxy. This communication summarizes our recent results on PV devices and demonstrates the strength of this new technology.

The analysis of energy efficiency in water electrolysis under high temperature and high pressure

NASA Astrophysics Data System (ADS)

Hourng, L. W.; Tsai, T. T.; Lin, M. Y.

2017-11-01

This paper aims to analyze the energy efficiency of water electrolysis under high pressure and high temperature conditions. The effects of temperature and pressure on four different kinds of reaction mechanisms, namely, reversible voltage, activation polarization, ohmic polarization, and concentration polarization, are investigated in details. Results show that the ohmic and concentration over-potentials are increased as temperature is increased, however, the reversible and activation over-potentials are decreased as temperature is increased. Therefore, the net efficiency is enhanced as temperature is increased. The efficiency of water electrolysis at 350°C/100 bars is increased about 17%, compared with that at 80°C/1bar.

Advanced Power Electronics Components

NASA Technical Reports Server (NTRS)

Schwarze, Gene E.

2004-01-01

This paper will give a description and status of the Advanced Power Electronics Materials and Components Technology program being conducted by the NASA Glenn Research Center for future aerospace power applications. The focus of this research program is on the following: 1) New and/or significantly improved dielectric materials for the development of power capacitors with increased volumetric efficiency, energy density, and operating temperature. Materials being investigated include nanocrystalline and composite ceramic dielectrics and diamond-like carbon films; 2) New and/or significantly improved high frequency, high temperature, low loss soft magnetic materials for the development of transformers/inductors with increased power/energy density, electrical efficiency, and operating temperature. Materials being investigated include nanocrystalline and nanocomposite soft magnetic materials; 3) Packaged high temperature, high power density, high voltage, and low loss SiC diodes and switches. Development of high quality 4H- and 6H- SiC atomically smooth substrates to significantly improve device performance is a major emphasis of the SiC materials program; 4) Demonstration of high temperature (> 200 C) circuits using the components developed above.

Rotor Performance at High Advance Ratio: Theory versus Test

NASA Technical Reports Server (NTRS)

Harris, Franklin D.

2008-01-01

Five analytical tools have been used to study rotor performance at high advance ratio. One is representative of autogyro rotor theory in 1934 and four are representative of helicopter rotor theory in 2008. The five theories are measured against three sets of well documented, full-scale, isolated rotor performance experiments. The major finding of this study is that the decades spent by many rotorcraft theoreticians to improve prediction of basic rotor aerodynamic performance has paid off. This payoff, illustrated by comparing the CAMRAD II comprehensive code and Wheatley & Bailey theory to H-34 test data, shows that rational rotor lift to drag ratios are now predictable. The 1934 theory predicted L/D ratios as high as 15. CAMRAD II predictions compared well with H-34 test data having L/D ratios more on the order of 7 to 9. However, the detailed examination of the selected codes compared to H-34 test data indicates that not one of the codes can predict to engineering accuracy above an advance ratio of 0.62 the control positions and shaft angle of attack required for a given lift. There is no full-scale rotor performance data available for advance ratios above 1.0 and extrapolation of currently available data to advance ratios on the order of 2.0 is unreasonable despite the needs of future rotorcraft. Therefore, it is recommended that an overly strong full-scale rotor blade set be obtained and tested in a suitable wind tunnel to at least an advance ratio of 2.5. A tail rotor from a Sikorsky CH-53 or other large single rotor helicopter should be adequate for this exploratory experiment.

Investigation of high efficiency GaAs solar cells

NASA Technical Reports Server (NTRS)

Olsen, Larry C.; Dunham, Glen; Addis, F. W.; Huber, Dan; Linden, Kurt

1989-01-01

Investigations of basic mechanisms which limit the performance of high efficiency GaAs solar cells are discussed. P/N heteroface structures have been fabricated from MOCVD epiwafers. Typical AM1 efficiencies are in the 21 to 22 percent range, with a SERI measurement for one cell being 21.5 percent. The cells are nominally 1.5 x 1.5 cm in size. Studies have involved photoresponse, T-I-V analyses, and interpretation of data in terms of appropriate models to determine key cell parameters. Results of these studies are utilized to determine future approaches for increasing GaAs solar cell efficiencies.

An Updated Assessment of NASA Ultra-Efficient Engine Technologies

NASA Technical Reports Server (NTRS)

Tong Michael T.; Jones, Scott M.

2005-01-01

NASA's Ultra Efficient Engine Technology (UEET) project features advanced aeropropulsion technologies that include highly loaded turbomachinery, an advanced low-NOx combustor, high-temperature materials, and advanced fan containment technology. A probabilistic system assessment is performed to evaluate the impact of these technologies on aircraft CO2 (or equivalent fuel burn) and NOx reductions. A 300-passenger aircraft, with two 396-kN thrust (85,000-lb) engines is chosen for the study. The results show that a large subsonic aircraft equipped with the current UEET technology portfolio has very high probabilities of meeting the UEET minimum success criteria for CO2 reduction (-12% from the baseline) and LTO (landing and takeoff) NOx reductions (-65% relative to the 1996 International Civil Aviation Organization rule).

Cutting efficiency of diamond burs operated with electric high-speed dental handpiece on zirconia.

PubMed

Nakamura, Keisuke; Katsuda, Yusuke; Ankyu, Shuhei; Harada, Akio; Tenkumo, Taichi; Kanno, Taro; Niwano, Yoshimi; Egusa, Hiroshi; Milleding, Percy; Örtengren, Ulf

2015-10-01

Zirconia-based dental restorations are becoming used more commonly. However, limited attention has been given to the difficulties experienced, concerning cutting, in removing the restorations when needed. The aim of the present study was to compare the cutting efficiency of diamond burs, operated using an electric high-speed dental handpiece, on zirconia (Zir) with those on lithium disilicate glass-ceramic (LD) and leucite glass-ceramic (L). In addition, evaluation of the cutting efficiency of diamond burs on Zir of different thicknesses was performed. Specimens of Zir were prepared with thicknesses of 0.5, 1.0, 2.0, and 4.0 mm, and specimens of LD and L were prepared with a thickness of 1.0 mm. Cutting tests were performed using diamond burs with super coarse (SC) and coarse (C) grains. The handpiece was operated at 150,000 rpm with a cutting force of 0.9 N. The results demonstrated that cutting of Zir took about 1.5- and 7-fold longer than cutting of LD and L, respectively. The SC grains showed significantly higher cutting efficiency on Zir than the C grains. However, when the thickness of Zir increased, the cutting depth was significantly decreased. As it is suggested that cutting of zirconia is time consuming, this should be taken into consideration in advance when working with zirconia restorations. © 2015 Eur J Oral Sci.

The Energy Efficiency of High Intensity Proton Driver Concepts

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yakovlev, Vyacheslav; Grillenberger, Joachim; Kim, Sang-Ho

2017-05-01

For MW class proton driver accelerators the energy efficiency is an important aspect; the talk reviews the efficiency of different accelerator concepts including s.c./n.c. linac, rapid cycling synchrotron, cyclotron; the potential of these concepts for very high beam power is discussed.

Experimental Demonstration of a Highly Efficient Fan-out Polarization Grating

PubMed Central

Wan, Chenhao; Chen, Jian; Tang, Xiahui; Zhan, Qiwen

2016-01-01

Highly efficient fan-out elements are crucial in coherent beam combining architectures especially in coupled laser resonators where the beam passes through the fan-out element twice per round trip. Although the theoretical efficiency is usually less than 86%, the Dammann gratings are ubiquitously utilized in a variety of types of coherent beam combining systems due to the facile design and fabrication. In the current paper, we experimentally demonstrate a highly efficient fan-out polarization grating. It is the first time to our knowledge that all the three space-variant parameters of a polarization grating are simultaneously optimized to achieve the function of multi-beam splitting. Besides the high fan-out efficiency, the ability to control the polarization states of individual split beams is another advantage of this polarization grating. The novel polarization grating is promising to find applications in laser beam combining systems. PMID:28008972

Advanced Technology Spark-Ignition Aircraft Piston Engine Design Study

NASA Technical Reports Server (NTRS)

Stuckas, K. J.

1980-01-01

The advanced technology, spark ignition, aircraft piston engine design study was conducted to determine the improvements that could be made by taking advantage of technology that could reasonably be expected to be made available for an engine intended for production by January 1, 1990. Two engines were proposed to account for levels of technology considered to be moderate risk and high risk. The moderate risk technology engine is a homogeneous charge engine operating on avgas and offers a 40% improvement in transportation efficiency over present designs. The high risk technology engine, with a stratified charge combustion system using kerosene-based jet fuel, projects a 65% improvement in transportation efficiency. Technology enablement program plans are proposed herein to set a timetable for the successful integration of each item of required advanced technology into the engine design.

Streptavidin-functionalized capillary immune microreactor for highly efficient chemiluminescent immunoassay.

PubMed

Yang, Zhanjun; Zong, Chen; Ju, Huangxian; Yan, Feng

2011-11-07

A streptavidin functionalized capillary immune microreactor was designed for highly efficient flow-through chemiluminescent (CL) immunoassay. The functionalized capillary could be used as both a support for highly efficient immobilization of antibody and a flow cell for flow-through immunoassay. The functionalized inner wall and the capture process were characterized using scanning electron microscopy. Compared to conventional packed tube or thin-layer cell immunoreactor, the proposed microreactor showed remarkable properties such as lower cost, simpler fabrication, better practicality and wider dynamic range for fast CL immunoassay with good reproducibility and stability. Using α-fetoprotein as model analyte, the highly efficient CL flow-through immunoassay system showed a linear range of 3 orders of magnitude from 0.5 to 200 ng mL(-1) and a low detection limit of 0.1 ng mL(-1). The capillary immune microreactor could make up the shortcoming of conventional CL immunoreactors and provided a promising alternative for highly efficient flow-injection immunoassay. Copyright © 2011 Elsevier B.V. All rights reserved.

Development, Qualification and Production of Space Solar Cells with 30% EOL Efficiency

NASA Astrophysics Data System (ADS)

Guter, Wolfgang; Ebel, Lars; Fuhrmann, Daniel; Kostler, Wolfgang; Meusel, Matthias

2014-08-01

AZUR SPACE's latest qualified solar cell product 3G30-advanced provides a high end-of-life (EOL) efficiency of 27.8% for 5E14 (1 MeV e-/cm2) at low production costs. In order to further reduce the mass, the 3G30-advanced was thinned down to as thin as 20 μm and tested in space. Next generation solar cells must exceed the EOL efficiency of the 3G30-advanced and therefore will utilize the excess current of the Ge subcell. This can be achieved by a metamorphic cell concept. While average beginning-of-life efficiencies above 31% have already been demonstrated with upright metamorphic triple-junction cells, AZUR's next generation product will comprise a metamorphic 4- junction device targeting 30% EOL.

Raytheon advanced pulse-tube cryocoolers

NASA Astrophysics Data System (ADS)

Conrad, Ted; Yates, Ryan; Kuo, Daniel; Schaefer, Brian; Arnoult, Matt

2016-05-01

Since the 1970s, Raytheon has developed, built, tested and integrated high performance cryocoolers. Our versatile designs for single and multi-stage cryocoolers provide reliable operation for temperatures from 10 to 200 Kelvin with power levels ranging from 50 W to nearly 600 W. These cryocoolers incorporate clearance seals, flexure suspensions, hermetic housings and dynamic balancing to provide long service life and reliable operation in all relevant environments. Recently, Raytheon has developed an advanced regenerator technology capable of operating efficiently at high frequencies and outperforming traditional screen regenerators. The Raytheon Advanced Miniature (RAM-100) cryocooler, a flight packaged, high frequency, single stage pulse tube cooler with an integrated surge volume and inertance tube, has been designed for use with this regenerator. Design details and experimentally measured performance of two iterations of the RAM cryocooler are presented in this paper.

Highly efficient light management for perovskite solar cells

PubMed Central

Wang, Dong-Lin; Cui, Hui-Juan; Hou, Guo-Jiao; Zhu, Zhen-Gang; Yan, Qing-Bo; Su, Gang

2016-01-01

Organic-inorganic halide perovskite solar cells have enormous potential to impact the existing photovoltaic industry. As realizing a higher conversion efficiency of the solar cell is still the most crucial task, a great number of schemes were proposed to minimize the carrier loss by optimizing the electrical properties of the perovskite solar cells. Here, we focus on another significant aspect that is to minimize the light loss by optimizing the light management to gain a high efficiency for perovskite solar cells. In our scheme, the slotted and inverted prism structured SiO2 layers are adopted to trap more light into the solar cells, and a better transparent conducting oxide layer is employed to reduce the parasitic absorption. For such an implementation, the efficiency and the serviceable angle of the perovskite solar cell can be promoted impressively. This proposal would shed new light on developing the high-performance perovskite solar cells. PMID:26733112

Lightweight High Efficiency Electric Motors for Space Applications

NASA Technical Reports Server (NTRS)

Robertson, Glen A.; Tyler, Tony R.; Piper, P. J.

2011-01-01

Lightweight high efficiency electric motors are needed across a wide range of space applications from - thrust vector actuator control for launch and flight applications to - general vehicle, base camp habitat and experiment control for various mechanisms to - robotics for various stationary and mobile space exploration missions. QM Power?s Parallel Path Magnetic Technology Motors have slowly proven themselves to be a leading motor technology in this area; winning a NASA Phase II for "Lightweight High Efficiency Electric Motors and Actuators for Low Temperature Mobility and Robotics Applications" a US Army Phase II SBIR for "Improved Robot Actuator Motors for Medical Applications", an NSF Phase II SBIR for "Novel Low-Cost Electric Motors for Variable Speed Applications" and a DOE SBIR Phase I for "High Efficiency Commercial Refrigeration Motors" Parallel Path Magnetic Technology obtains the benefits of using permanent magnets while minimizing the historical trade-offs/limitations found in conventional permanent magnet designs. The resulting devices are smaller, lower weight, lower cost and have higher efficiency than competitive permanent magnet and non-permanent magnet designs. QM Power?s motors have been extensively tested and successfully validated by multiple commercial and aerospace customers and partners as Boeing Research and Technology. Prototypes have been made between 0.1 and 10 HP. They are also in the process of scaling motors to over 100kW with their development partners. In this paper, Parallel Path Magnetic Technology Motors will be discussed; specifically addressing their higher efficiency, higher power density, lighter weight, smaller physical size, higher low end torque, wider power zone, cooler temperatures, and greater reliability with lower cost and significant environment benefit for the same peak output power compared to typically motors. A further discussion on the inherent redundancy of these motors for space applications will be provided.

Advanced Energy Efficient Roof System

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jane Davidson

2008-09-30

Energy consumption in buildings represents 40 percent of primary U.S. energy consumption, split almost equally between residential (22%) and commercial (18%) buildings.1 Space heating (31%) and cooling (12%) account for approximately 9 quadrillion Btu. Improvements in the building envelope can have a significant impact on reducing energy consumption. Thermal losses (or gains) from the roof make up 14 percent of the building component energy load. Infiltration through the building envelope, including the roof, accounts for an additional 28 percent of the heating loads and 16 percent of the cooling loads. These figures provide a strong incentive to develop and implementmore » more energy efficient roof systems. The roof is perhaps the most challenging component of the building envelope to change for many reasons. The engineered roof truss, which has been around since 1956, is relatively low cost and is the industry standard. The roof has multiple functions. A typical wood frame home lasts a long time. Building codes vary across the country. Customer and trade acceptance of new building products and materials may impede market penetration. The energy savings of a new roof system must be balanced with other requirements such as first and life-cycle costs, durability, appearance, and ease of construction. Conventional residential roof construction utilizes closely spaced roof trusses supporting a layer of sheathing and roofing materials. Gypsum board is typically attached to the lower chord of the trusses forming the finished ceiling for the occupied space. Often in warmer climates, the HVAC system and ducts are placed in the unconditioned and otherwise unusable attic. High temperature differentials and leaky ducts result in thermal losses. Penetrations through the ceilings are notoriously difficult to seal and lead to moisture and air infiltration. These issues all contribute to greater energy use and have led builders to consider construction of a conditioned attic

Efficient High Performance Collective Communication for Distributed Memory Environments

ERIC Educational Resources Information Center

Ali, Qasim

2009-01-01

Collective communication allows efficient communication and synchronization among a collection of processes, unlike point-to-point communication that only involves a pair of communicating processes. Achieving high performance for both kernels and full-scale applications running on a distributed memory system requires an efficient implementation of…

Fundamental Aeronautics Program: Overview of Project Work in Supersonic Cruise Efficiency

NASA Technical Reports Server (NTRS)

Castner, Raymond

2011-01-01

The Supersonics Project, part of NASA?s Fundamental Aeronautics Program, contains a number of technical challenge areas which include sonic boom community response, airport noise, high altitude emissions, cruise efficiency, light weight durable engines/airframes, and integrated multi-discipline system design. This presentation provides an overview of the current (2011) activities in the supersonic cruise efficiency technical challenge, and is focused specifically on propulsion technologies. The intent is to develop and validate high-performance supersonic inlet and nozzle technologies. Additional work is planned for design and analysis tools for highly-integrated low-noise, low-boom applications. If successful, the payoffs include improved technologies and tools for optimized propulsion systems, propulsion technologies for a minimized sonic boom signature, and a balanced approach to meeting efficiency and community noise goals. In this propulsion area, the work is divided into advanced supersonic inlet concepts, advanced supersonic nozzle concepts, low fidelity computational tool development, high fidelity computational tools, and improved sensors and measurement capability. The current work in each area is summarized.

High-efficiency K-band tracking antenna feed

NASA Technical Reports Server (NTRS)

Beavin, R. L.; Simanyi, A. I.

1975-01-01

Antenna feed features high aperture efficiency of multimode near-field horn and develops tracking signals without conventional monopulse bridge. Feed assembly is relatively simple and very compact. However, feed is sensitive to cross-polarized energy which couples into orthogonal error channel.

High-concentration planar microtracking photovoltaic system exceeding 30% efficiency

NASA Astrophysics Data System (ADS)

Price, Jared S.; Grede, Alex J.; Wang, Baomin; Lipski, Michael V.; Fisher, Brent; Lee, Kyu-Tae; He, Junwen; Brulo, Gregory S.; Ma, Xiaokun; Burroughs, Scott; Rahn, Christopher D.; Nuzzo, Ralph G.; Rogers, John A.; Giebink, Noel C.

2017-08-01

Prospects for concentrating photovoltaic (CPV) power are growing as the market increasingly values high power conversion efficiency to leverage now-dominant balance of system and soft costs. This trend is particularly acute for rooftop photovoltaic power, where delivering the high efficiency of traditional CPV in the form factor of a standard rooftop photovoltaic panel could be transformative. Here, we demonstrate a fully automated planar microtracking CPV system <2 cm thick that operates at fixed tilt with a microscale triple-junction solar cell at >660× concentration ratio over a 140∘ full field of view. In outdoor testing over the course of two sunny days, the system operates automatically from sunrise to sunset, outperforming a 17%-efficient commercial silicon solar cell by generating >50% more energy per unit area per day in a direct head-to-head competition. These results support the technical feasibility of planar microtracking CPV to deliver a step change in the efficiency of rooftop solar panels at a commercially relevant concentration ratio.

Analysis of high-efficiency widely-tunable N-resonances in Cs vapor

NASA Astrophysics Data System (ADS)

Krasteva, A.; Gateva, S.; Tzvetkov, S.; Ghosh, P. N.; Sargsyan, A.; Cartaleva, S.

2018-03-01

The narrow-band coherent N-type resonance, promising for the development of advanced atomic clocks, can be considered as a type of three-photon resonance, where a two-photon Raman excitation is combined with a resonant optical pumping field. In this communication, we present an experimental study and a theoretical analysis related to three-photon, bi-chromatic excitation of Cs atomic vapor contained in an 8-mm long cell with 20 Torr of neon. If a coupling laser is fixed at a frequency that is lower by several GHz than the position of the absorption profile of the Fg = 4 set of transitions, and a probe laser is tuned over the D2 line (λ = 852 nm), a narrow high-contrast enhanced absorption N-resonance will be observed in the probe light profile, superimposed on the absorption profile of the Fg = 4 set of transitions. We present theoretical modeling aimed to clarify the processes behind the efficiency of the N-resonance preparation for different frequency positions of the coupling laser within the D2 line of Cs.

Recent advances in the design of tailored nanomaterials for efficient oxygen reduction reaction

DOE PAGES

Lv, Haifeng; Li, Dongguo; Strmcnik, Dusan; ...

2016-04-11

In the past decade, polymer electrolyte membrane fuels (PEMFCs) have been evaluated for both automotive and stationary applications. One of the main obstacles for large scale commercialization of this technology is related to the sluggish oxygen reduction reaction that takes place on the cathode side of fuel cell. Consequently, ongoing research efforts are focused on the design of cathode materials that could improve the kinetics and durability. Majority of these efforts rely on novel synthetic approaches that provide control over the structure, size, shape and composition of catalytically active materials. This article highlights the most recent advances that have beenmore » made to tailor critical parameters of the nanoscale materials in order to achieve more efficient performance of the oxygen reduction reaction (ORR).« less

Advancements in high-power diode laser stacks for defense applications

NASA Astrophysics Data System (ADS)

Pandey, Rajiv; Merchen, David; Stapleton, Dean; Patterson, Steve; Kissel, Heiko; Fassbender, Wilhlem; Biesenbach, Jens

2012-06-01

This paper reports on the latest advancements in vertical high-power diode laser stacks using micro-channel coolers, which deliver the most compact footprint, power scalability and highest power/bar of any diode laser package. We present electro-optical (E-O) data on water-cooled stacks with wavelengths ranging from 7xx nm to 9xx nm and power levels of up to 5.8kW, delivered @ 200W/bar, CW mode, and a power-conversion efficiency of >60%, with both-axis collimation on a bar-to-bar pitch of 1.78mm. Also, presented is E-O data on a compact, conductively cooled, hardsoldered, stack package based on conventional CuW and AlN materials, with bar-to-bar pitch of 1.8mm, delivering average power/bar >15W operating up to 25% duty cycle, 10ms pulses @ 45C. The water-cooled stacks can be used as pump-sources for diode-pumped alkali lasers (DPALs) or for more traditional diode-pumped solid-state lasers (DPSSL). which are power/brightness scaled for directed energy weapons applications and the conductively-cooled stacks as illuminators.

Report of high quantum efficiency photocathode at Milano

DOE Office of Scientific and Technical Information (OSTI.GOV)

Michelato, P.

R D activity on high quantum efficiency alkali antimonide photocathode is in progress at Milano, in the context of the ARES program. Inside a preliminary preparation chamber, Cs[sub 3]Sb layers with qunatum efficiency up to 9% (at [lambda]=543.5 nm) and lifetime of some days has been recently produced on copper, stainless steel and niobium, using a reproducible deposition procedure adapted to the material of the different substrata.

High-Aperture-Efficiency Horn Antenna

NASA Technical Reports Server (NTRS)

Pickens, Wesley; Hoppe, Daniel; Epp, Larry; Kahn, Abdur

2005-01-01

A horn antenna (see Figure 1) has been developed to satisfy requirements specific to its use as an essential component of a high-efficiency Ka-band amplifier: The combination of the horn antenna and an associated microstrip-patch antenna array is required to function as a spatial power divider that feeds 25 monolithic microwave integrated-circuit (MMIC) power amplifiers. The foregoing requirement translates to, among other things, a further requirement that the horn produce a uniform, vertically polarized electromagnetic field in its patches identically so that the MMICs can operate at maximum efficiency. The horn is fed from a square waveguide of 5.9436-mm-square cross section via a transition piece. The horn features cosine-tapered, dielectric-filled longitudinal corrugations in its vertical walls to create a hard boundary condition: This aspect of the horn design causes the field in the horn aperture to be substantially vertically polarized and to be nearly uniform in amplitude and phase. As used here, cosine-tapered signifies that the depth of the corrugations is a cosine function of distance along the horn. Preliminary results of finite-element simulations of performance have shown that by virtue of the cosine taper the impedance response of this horn can be expected to be better than has been achieved previously in a similar horn having linearly tapered dielectric- filled longitudinal corrugations. It is possible to create a hard boundary condition by use of a single dielectric-filled corrugation in each affected wall, but better results can be obtained with more corrugations. Simulations were performed for a one- and a three-corrugation cosine-taper design. For comparison, a simulation was also performed for a linear- taper design (see Figure 2). The three-corrugation design was chosen to minimize the cost of fabrication while still affording acceptably high performance. Future designs using more corrugations per wavelength are expected to provide better

High-efficiency fiber-to-chip grating couplers realized using an advanced CMOS-compatible silicon-on-insulator platform.

PubMed

Vermeulen, D; Selvaraja, S; Verheyen, P; Lepage, G; Bogaerts, W; Absil, P; Van Thourhout, D; Roelkens, G

2010-08-16

A new generation of Silicon-on-Insulator fiber-to-chip grating couplers which use a silicon overlay to enhance the directionality and thereby the coupling efficiency is presented. Devices are realized on a 200 mm wafer in a CMOS pilot line. The fabricated fiber couplers show a coupling efficiency of -1.6 dB and a 3 dB bandwidth of 80 nm.

Advanced sensors and instrumentation

NASA Technical Reports Server (NTRS)

Calloway, Raymond S.; Zimmerman, Joe E.; Douglas, Kevin R.; Morrison, Rusty

1990-01-01

NASA is currently investigating the readiness of Advanced Sensors and Instrumentation to meet the requirements of new initiatives in space. The following technical objectives and technologies are briefly discussed: smart and nonintrusive sensors; onboard signal and data processing; high capacity and rate adaptive data acquisition systems; onboard computing; high capacity and rate onboard storage; efficient onboard data distribution; high capacity telemetry; ground and flight test support instrumentation; power distribution; and workstations, video/lighting. The requirements for high fidelity data (accuracy, frequency, quantity, spatial resolution) in hostile environments will continue to push the technology developers and users to extend the performance of their products and to develop new generations.

Advanced high temperature materials for the energy efficient automotive Stirling engine

NASA Technical Reports Server (NTRS)

Titran, R. H.; Stephens, J. R.

1984-01-01

The Stirling Engine is under investigated jointly by the Department of Energy and NASA Lewis as an alternative to the internal combustion engine for automotive applications. The Stirling Engine is an external combustion engine that offers the advantage of high fuel economy, low emissions, low noise, and low vibrations compared to current internal combustion automotive engines. The most critical component from a materials viewpoint is the heater head consisting of the cylinders, heating tubes, and regenerator housing. Materials requirements for the heater head include compatibility with hydrogen, resistance to hydrogen permeation, high temperature oxidation/corrosion resistance and high temperature creep-rupture and fatigue properties. A continuing supporting materials research and technology program has identified the wrought alloys CG-27 and 12RN72 and the cast alloys XF-818 and NASAUT 4G-A1 as candidate replacements for the cobalt containing alloys used in current prototype engines. Based on the materials research program in support of the automotive Stirling engine it is concluded that manufacture of the engine is feasible from low cost iron-base alloys rather than the cobalt alloys rather than the cobalt alloys used in prototype engines. This paper will present results of research that led to this conclusion.

Ultra Clean 1.1MW High Efficiency Natural Gas Engine Powered System

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zurlo, James; Lueck, Steve

Dresser, Inc. (GE Energy, Waukesha gas engines) will develop, test, demonstrate, and commercialize a 1.1 Megawatt (MW) natural gas fueled combined heat and power reciprocating engine powered package. This package will feature a total efficiency > 75% and ultra low CARB permitting emissions. Our modular design will cover the 1 – 6 MW size range, and this scalable technology can be used in both smaller and larger engine powered CHP packages. To further advance one of the key advantages of reciprocating engines, the engine, generator and CHP package will be optimized for low initial and operating costs. Dresser, Inc. willmore » leverage the knowledge gained in the DOE - ARES program. Dresser, Inc. will work with commercial, regulatory, and government entities to help break down barriers to wider deployment of CHP. The outcome of this project will be a commercially successful 1.1 MW CHP package with high electrical and total efficiency that will significantly reduce emissions compared to the current central power plant paradigm. Principal objectives by phases for Budget Period 1 include: • Phase 1 – market study to determine optimum system performance, target first cost, lifecycle cost, and creation of a detailed product specification. • Phase 2 – Refinement of the Waukesha CHP system design concepts, identification of critical characteristics, initial evaluation of technical solutions, and risk mitigation plans. Background« less

Recent advances in high-throughput QCL-based infrared microspectral imaging (Conference Presentation)

NASA Astrophysics Data System (ADS)

Rowlette, Jeremy A.; Fotheringham, Edeline; Nichols, David; Weida, Miles J.; Kane, Justin; Priest, Allen; Arnone, David B.; Bird, Benjamin; Chapman, William B.; Caffey, David B.; Larson, Paul; Day, Timothy

2017-02-01

The field of infrared spectral imaging and microscopy is advancing rapidly due in large measure to the recent commercialization of the first high-throughput, high-spatial-definition quantum cascade laser (QCL) microscope. Having speed, resolution and noise performance advantages while also eliminating the need for cryogenic cooling, its introduction has established a clear path to translating the well-established diagnostic capability of infrared spectroscopy into clinical and pre-clinical histology, cytology and hematology workflows. Demand for even higher throughput while maintaining high-spectral fidelity and low-noise performance continues to drive innovation in QCL-based spectral imaging instrumentation. In this talk, we will present for the first time, recent technological advances in tunable QCL photonics which have led to an additional 10X enhancement in spectral image data collection speed while preserving the high spectral fidelity and SNR exhibited by the first generation of QCL microscopes. This new approach continues to leverage the benefits of uncooled microbolometer focal plane array cameras, which we find to be essential for ensuring both reproducibility of data across instruments and achieving the high-reliability needed in clinical applications. We will discuss the physics underlying these technological advancements as well as the new biomedical applications these advancements are enabling, including automated whole-slide infrared chemical imaging on clinically relevant timescales.

Boiling and quenching heat transfer advancement by nanoscale surface modification.

PubMed

Hu, Hong; Xu, Cheng; Zhao, Yang; Ziegler, Kirk J; Chung, J N

2017-07-21

All power production, refrigeration, and advanced electronic systems depend on efficient heat transfer mechanisms for achieving high power density and best system efficiency. Breakthrough advancement in boiling and quenching phase-change heat transfer processes by nanoscale surface texturing can lead to higher energy transfer efficiencies, substantial energy savings, and global reduction in greenhouse gas emissions. This paper reports breakthrough advancements on both fronts of boiling and quenching. The critical heat flux (CHF) in boiling and the Leidenfrost point temperature (LPT) in quenching are the bottlenecks to the heat transfer advancements. As compared to a conventional aluminum surface, the current research reports a substantial enhancement of the CHF by 112% and an increase of the LPT by 40 K using an aluminum surface with anodized aluminum oxide (AAO) nanoporous texture finish. These heat transfer enhancements imply that the power density would increase by more than 100% and the quenching efficiency would be raised by 33%. A theory that links the nucleation potential of the surface to heat transfer rates has been developed and it successfully explains the current finding by revealing that the heat transfer modification and enhancement are mainly attributed to the superhydrophilic surface property and excessive nanoscale nucleation sites created by the nanoporous surface.

Ka-Band TWT High-Efficiency Power Combiner for High-Rate Data Transmission

NASA Technical Reports Server (NTRS)

Wintucky, Edwin G.; Simons, Rainee; Vaden, Karl R.; Lesny, Gary G.; Glass, Jeffrey L.

2007-01-01

A four-port magic-T hybrid waveguide junction serves as the central component of a high-efficiency two-way power combiner circuit for transmitting a high-rate phase-modulated digital signal at a carrier frequency in the Ka-band (between 27 and 40 GHz). This power combiner was developed to satisfy a specific requirement to efficiently combine the coherent outputs of two traveling-wavetube (TWT) amplifiers that are typically characterized by power levels on the order of 100 W or more. In this application, the use of a waveguide-based power combiner (instead of a coaxial-cable- or microstrip-based power combiner, for example) is dictated by requirements for low loss, high power-handling capability, and broadband response. Combiner efficiencies were typically 90 percent or more over both the linear and saturated output power regions of operation of the TWTs . Figure 1 depicts the basic configuration of the magic-T hybrid junction. The coherent outputs of the two TWTs enter through ports 1 and 4. As a result of the orientations of the electromagnetic fields, which also provides a needed high port-to-port isolation, of these two input signals and the interior design of the magic-T junction, the input powers are divided so as to add in phase at one output port (port 2), and to be opposite in phase and hence cancel each other at the opposite coplanar output port (port 3). The net result is that the output power at port 2 is essentially double that of the output of one TWT, minus the power lost in the magic-T hybrid junction. Optimum performance as a high-efficiency power combiner thus requires a balance of both power and phase at the input ports of the magic-T. Replicas of this two-way combiner can be arranged in a binary configuration to obtain a 2n-way (where n is an integer) combiner. For example, Figure 2 illustrates the use of three two-way combiners to combine the outputs of four TWTs.

Summary of efficiency testing of standard and high-capacity high-efficiency particulate air filters subjected to simulated tornado depressurization and explosive shock waves

DOE Office of Scientific and Technical Information (OSTI.GOV)

Smith, P.R.; Gregory, W.S.

1985-04-01

Pressure transients in nuclear facility air cleaning systems can originate from natural phenomena such as tornadoes or from accident-induced explosive blast waves. This study was concerned with the effective efficiency of high-efficiency particulate air (HEPA) filters during pressure surges resulting from simulated tornado and explosion transients. The primary objective of the study was to examine filter efficiencies at pressure levels below the point of structural failure. Both standard and high-capacity 0.61-m by 0.61-m HEPA filters were evaluated, as were several 0.2-m by 0.2-m HEPA filters. For a particular manufacturer, the material release when subjected to tornado transients is the samemore » (per unit area) for both the 0.2-m by 0.2-m and the 0.61-m by 0.61-m filters. For tornado transients, the material release was on the order of micrograms per square meter. When subjecting clean HEPA filters to simulated tornado transients with aerosol entrained in the pressure pulse, all filters tested showed a degradation of filter efficiency. For explosive transients, the material release from preloaded high-capacity filters was as much as 340 g. When preloaded high-capacity filters were subjected to shock waves approximately 50% of the structural limit level, 1 to 2 mg of particulate was released.« less

Highly efficient green phosphorescent organic light emitting diodes with improved efficiency roll-off

NASA Astrophysics Data System (ADS)

Thangaraju, K.; Lee, Jonghee; Lee, Jeong-Ik; Chu, Hye Yong; Kim, Yun-Hi; Kwon, Soon-Ki

2015-06-01

A 10-nm thick 4,4',4″-tris(carbazole-9-yl)tri-phenylamine (TcTa) interlayer effectively confines triplet excitons within the emissive layer (EML) of phosphorescent organic light emitting diodes (PHOLEDs) based on green-emitting Ir(ppy)3 dopant and improves the charge balance in the EML of the device, resulting the higher device efficiencies of 61.7 cd/A, 19.7 %, and 43.2 lm/W with the maximum luminance of 75,310 cd/m2 and highly improved efficiency roll-off (22.2% at 20 mA/cm2) when compared to those (61.1 cd/A, 19.6 %, and 47.2 lm/W with a maximum luminance of 38,350 cd/m2) of the standard device with efficiency roll-off of 62.3 % at 20 mA/cm2.

Adoption of high technology medical imaging and hospital quality and efficiency: Towards a conceptual framework.

PubMed

Sandoval, Guillermo A; Brown, Adalsteinn D; Wodchis, Walter P; Anderson, Geoffrey M

2018-05-17

Measuring the value of medical imaging is challenging, in part, due to the lack of conceptual frameworks underlying potential mechanisms where value may be assessed. To address this gap, this article proposes a framework that builds on the large body of literature on quality of hospital care and the classic structure-process-outcome paradigm. The framework was also informed by the literature on adoption of technological innovations and introduces 2 distinct though related aspects of imaging technology not previously addressed specifically in the literature on quality of hospital care: adoption (a structural hospital characteristic) and use (an attribute of the process of care). The framework hypothesizes a 2-part causality where adoption is proposed to be a central, linking factor between hospital structural characteristics, market factors, and hospital outcomes (ie, quality and efficiency). The first part indicates that hospital structural characteristics and market factors influence or facilitate the adoption of high technology medical imaging within an institution. The presence of this technology, in turn, is hypothesized to improve the ability of the hospital to deliver high quality and efficient care. The second part describes this ability throughout 3 main mechanisms pointing to the importance of imaging use on patients, to the presence of staff and qualified care providers, and to some elements of organizational capacity capturing an enhanced clinical environment. The framework has the potential to assist empirical investigations of the value of adoption and use of medical imaging, and to advance understanding of the mechanisms that produce quality and efficiency in hospitals. Copyright © 2018 John Wiley & Sons, Ltd.

Development of a high efficiency thin silicon solar cell

NASA Technical Reports Server (NTRS)

Storti, G.; Culik, J.; Wrigley, C.

1980-01-01

Significant improvements in open-circuit voltage and conversion efficiency, even on relatively high bulk resistivity silicon, were achieved by using a screen-printed aluminum paste back surface field. A 4 sq cm 50 micron m thick cell was fabricated from textured 10 omega-cm silicon which had an open-circuit voltage of 595 mV and AMO conversion efficiency at 25 C of 14.3%. The best 4 sq cm 50 micron thick cell (2 omega-cm silicon) produced had an open-circuit voltage of 607 mV and an AMO conversion efficiency of 15%. Processing modifications are described which resulted in better front contact integrity and reduced breakage. These modifications were utilized in the thin cell pilot line to fabricate 4 sq cm cells with an average AMO conversion efficiency at 25 C of better than 12.5% and with lot yields as great as 51% of starts; a production rate of 10,000 cells per month was demonstrated. A pilot line was operated which produced large area (25 cm) ultra-thin cells with an average AMO conversion efficiency at 25 deg of better than 11.5% and a lot yield as high as 17%.

A metamaterial electromagnetic energy rectifying surface with high harvesting efficiency

NASA Astrophysics Data System (ADS)

Duan, Xin; Chen, Xing; Zhou, Lin

2016-12-01

A novel metamaterial rectifying surface (MRS) for electromagnetic energy capture and rectification with high harvesting efficiency is presented. It is fabricated on a three-layer printed circuit board, which comprises an array of periodic metamaterial particles in the shape of mirrored split rings, a metal ground, and integrated rectifiers employing Schottky diodes. Perfect impedance matching is engineered at two interfaces, i.e. one between free space and the surface, and the other between the metamaterial particles and the rectifiers, which are connected through optimally positioned vias. Therefore, the incident electromagnetic power is captured with almost no reflection by the metamaterial particles, then channeled maximally to the rectifiers, and finally converted to direct current efficiently. Moreover, the rectifiers are behind the metal ground, avoiding the disturbance of high power incident electromagnetic waves. Such a MRS working at 2.45 GHz is designed, manufactured and measured, achieving a harvesting efficiency up to 66.9% under an incident power density of 5 mW/cm2, compared with a simulated efficiency of 72.9%. This high harvesting efficiency makes the proposed MRS an effective receiving device in practical microwave power transmission applications.

High Quantum Efficiency Nanopillar Photodiodes Overcoming the Diffraction Limit of Light.

PubMed

Lee, Wook-Jae; Senanayake, Pradeep; Farrell, Alan C; Lin, Andrew; Hung, Chung-Hong; Huffaker, Diana L

2016-01-13

InAs1-xSbx nanowires have recently attracted interest for infrared sensing applications due to the small bandgap and high thermal conductivity. However, previous reports on nanowire-based infrared sensors required low operating temperatures in order to mitigate the high dark current and have shown poor sensitivities resulting from reduced light coupling efficiency beyond the diffraction limit. Here, InAsSb nanopillar photodiodes with high quantum efficiency are achieved by partially coating the nanopillar with metal that excites localized surface plasmon resonances, leading to quantum efficiencies of ∼29% at 2390 nm. These high quantum efficiency nanopillar photodiodes, with 180 nm diameters and 1000 nm heights, allow operation at temperatures as high as 220 K and exhibit a detection wavelength up to 3000 nm, well beyond the diffraction limit. The InAsSb nanopillars are grown on low cost GaAs (111)B substrates using an InAs buffer layer, making our device architecture a promising path toward low-cost infrared focal plane arrays with high operating temperature.

Advanced Stirling Convertor Update

NASA Astrophysics Data System (ADS)

Wood, J. Gary; Carroll, Cliff; Matejczyk, Dan; Penswick, L. B.; Soendker, E.

2006-01-01

This paper reports on the 88 We Advanced Stirling Convertor (ASC) currently being developed under Phase II of a NASA NRA program for possible use in advanced high specific power radioisotope space power systems. An early developmental unit, the Frequency Test Bed (FTB) which was built and tested in Phase I demonstrated 36% efficiency. The ASC-1 currently being developed under Phase II, uses a high temperature heater head to allow for operation at 850 °C and is expected to have an efficiency approaching 40% (based on AC electrical out) at a temperature ratio of 3.1. The final lightweight ASC-2 convertor to be developed in Phase III is expected to have a mass of approximately 1 kg. The implementation of the ASC would allow for much higher specific power radioisotope power systems, requiring significantly less radioisotope fuel than current systems. The first run of the ASC-1 occurred in September 2005, and full temperature operation was achieved in early October 2005. Presented is an update on progress on the ASC program as well as the plans for future development. Also presented are efforts being performed to ensure the ASC has the required long life already demonstrated in free-piston Stirling cryocoolers.

Advanced processing for high-bandwidth sensor systems

NASA Astrophysics Data System (ADS)

Szymanski, John J.; Blain, Phil C.; Bloch, Jeffrey J.; Brislawn, Christopher M.; Brumby, Steven P.; Cafferty, Maureen M.; Dunham, Mark E.; Frigo, Janette R.; Gokhale, Maya; Harvey, Neal R.; Kenyon, Garrett; Kim, Won-Ha; Layne, J.; Lavenier, Dominique D.; McCabe, Kevin P.; Mitchell, Melanie; Moore, Kurt R.; Perkins, Simon J.; Porter, Reid B.; Robinson, S.; Salazar, Alfonso; Theiler, James P.; Young, Aaron C.

2000-11-01

Compute performance and algorithm design are key problems of image processing and scientific computing in general. For example, imaging spectrometers are capable of producing data in hundreds of spectral bands with millions of pixels. These data sets show great promise for remote sensing applications, but require new and computationally intensive processing. The goal of the Deployable Adaptive Processing Systems (DAPS) project at Los Alamos National Laboratory is to develop advanced processing hardware and algorithms for high-bandwidth sensor applications. The project has produced electronics for processing multi- and hyper-spectral sensor data, as well as LIDAR data, while employing processing elements using a variety of technologies. The project team is currently working on reconfigurable computing technology and advanced feature extraction techniques, with an emphasis on their application to image and RF signal processing. This paper presents reconfigurable computing technology and advanced feature extraction algorithm work and their application to multi- and hyperspectral image processing. Related projects on genetic algorithms as applied to image processing will be introduced, as will the collaboration between the DAPS project and the DARPA Adaptive Computing Systems program. Further details are presented in other talks during this conference and in other conferences taking place during this symposium.

Preparation of reflective CsI photocathodes with reproducible high quantum efficiency

NASA Astrophysics Data System (ADS)

Maier-Komor, P.; Bauer, B. B.; Friese, J.; Gernhäuser, R.; Kienle, P.; Körner, H. J.; Montermann, G.; Zeitelhack, K.

1995-02-01

CsI as a solid UV-photocathode material has many promising applications in fast gaseous photon detectors. They are proposed in large area Ring Imaging CHerenkov (RICH) devices in forthcoming experiments at various high-energy particle accelerators. A high photon-to-electron conversion efficiency is a basic requirement for the successful operation of these devices. High reproducible quantum efficiencies could be achieved with CsI layers prepared by electron beam evaporation from a water-cooled copper crucible. CsI films were deposited in the thickness range of 30 to 500 μg/cm 2. Absorption coefficients and quantum efficiencies were measured in the wavelength region of 150 nm to 250 nm. The influence of various evaporation parameters on the quantum efficiency were investigated.

Highly Efficient Porphyrin-Based OPV/Perovskite Hybrid Solar Cells with Extended Photoresponse and High Fill Factor.

PubMed

Gao, Ke; Zhu, Zonglong; Xu, Bo; Jo, Sae Byeok; Kan, Yuanyuan; Peng, Xiaobin; Jen, Alex K-Y

2017-12-01

Employing a layer of bulk-heterojunction (BHJ) organic semiconductors on top of perovskite to further extend its photoresponse is considered as a simple and promising way to enhance the efficiency of perovskite-based solar cells, instead of using tandem devices or near infrared (NIR)-absorbing Sn-containing perovskites. However, the progress made from this approach is quite limited because very few such hybrid solar cells can simultaneously show high short-circuit current (J SC ) and fill factor (FF). To find an appropriate NIR-absorbing BHJ is essential for highly efficient, organic, photovoltaics (OPV)/perovskite hybrid solar cells. The materials involved in the BHJ layer not only need to have broad photoresponse to increase J SC , but also possess suitable energy levels and high mobility to afford high V OC and FF. In this work, a new porphyrin is synthesized and blended with [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) to function as an efficient BHJ for OPV/perovskite hybrid solar cells. The extended photoresponse, well-matched energy levels, and high hole mobility from optimized BHJ morphology afford a very high power conversion efficiency (PCE) (19.02%) with high V oc , J SC , and FF achieved simultaneously. This is the highest value reported so far for such hybrid devices, which demonstrates the feasibility of further improving the efficiency of perovskite devices. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Design Strategies for Ultra-high Efficiency Photovoltaics

NASA Astrophysics Data System (ADS)

Warmann, Emily Cathryn

While concentrator photovoltaic cells have shown significant improvements in efficiency in the past ten years, once these cells are integrated into concentrating optics, connected to a power conditioning system and deployed in the field, the overall module efficiency drops to only 34 to 36%. This efficiency is impressive compared to conventional flat plate modules, but it is far short of the theoretical limits for solar energy conversion. Designing a system capable of achieving ultra high efficiency of 50% or greater cannot be achieved by refinement and iteration of current design approaches. This thesis takes a systems approach to designing a photovoltaic system capable of 50% efficient performance using conventional diode-based solar cells. The effort began with an exploration of the limiting efficiency of spectrum splitting ensembles with 2 to 20 sub cells in different electrical configurations. Incorporating realistic non-ideal performance with the computationally simple detailed balance approach resulted in practical limits that are useful to identify specific cell performance requirements. This effort quantified the relative benefit of additional cells and concentration for system efficiency, which will help in designing practical optical systems. Efforts to improve the quality of the solar cells themselves focused on the development of tunable lattice constant epitaxial templates. Initially intended to enable lattice matched multijunction solar cells, these templates would enable increased flexibility in band gap selection for spectrum splitting ensembles and enhanced radiative quality relative to metamorphic growth. The III-V material family is commonly used for multijunction solar cells both for its high radiative quality and for the ease of integrating multiple band gaps into one monolithic growth. The band gap flexibility is limited by the lattice constant of available growth templates. The virtual substrate consists of a thin III-V film with the desired

High-Efficiency Microwave Power Amplifier

NASA Technical Reports Server (NTRS)

Sims, Williams H.

2005-01-01

A high-efficiency power amplifier that operates in the S band (frequencies of the order of a few gigahertz) utilizes transistors operating under class-D bias and excitation conditions. Class-D operation has been utilized at lower frequencies, but, until now, has not been exploited in the S band. Nominally, in class D operation, a transistor is switched rapidly between "on" and "off" states so that at any given instant, it sustains either high current or high voltage, but not both at the same time. In the ideal case of zero "on" resistance, infinite "off" resistance, zero inductance and capacitance, and perfect switching, the output signal would be a perfect square wave. Relative to the traditional classes A, B, and C of amplifier operation, class D offers the potential to achieve greater power efficiency. In addition, relative to class-A amplifiers, class-D amplifiers are less likely to go into oscillation. In order to design this amplifier, it was necessary to derive mathematical models of microwave power transistors for incorporation into a larger mathematical model for computational simulation of the operation of a class-D microwave amplifier. The design incorporates state-of-the-art switching techniques applicable only in the microwave frequency range. Another major novel feature is a transmission-line power splitter/combiner designed with the help of phasing techniques to enable an approximation of a square-wave signal (which is inherently a wideband signal) to propagate through what would, if designed in a more traditional manner, behave as a more severely band-limited device (see figure). The amplifier includes an input, a driver, and a final stage. Each stage contains a pair of GaAs-based field-effect transistors biased in class D. The input signal can range from -10 to +10 dBm into a 50-ohm load. The table summarizes the performances of the three stages

High power klystrons for efficient reliable high power amplifiers

NASA Astrophysics Data System (ADS)

Levin, M.

1980-11-01

This report covers the design of reliable high efficiency, high power klystrons which may be used in both existing and proposed troposcatter radio systems. High Power (10 kW) klystron designs were generated in C-band (4.4 GHz to 5.0 GHz), S-band (2.5 GHz to 2.7 GHz), and L-band or UHF frequencies (755 MHz to 985 MHz). The tubes were designed for power supply compatibility and use with a vapor/liquid phase heat exchanger. Four (4) S-band tubes were developed in the course of this program along with two (2) matching focusing solenoids and two (2) heat exchangers. These tubes use five (5) tuners with counters which are attached to the focusing solenoids. A reliability mathematical model of the tube and heat exchanger system was also generated.

Separator Decoration with Cobalt/Nitrogen Codoped Carbon for Highly Efficient Polysulfide Confinement in Lithium-Sulfur Batteries.

PubMed

Hu, Wen; Hirota, Yuichiro; Zhu, Yexin; Yoshida, Nao; Miyamoto, Manabu; Zheng, Tao; Nishiyama, Norikazu

2017-09-22

A macro-/mesoporous Co-N-C-decorated separator is proposed to confine and reutilize migrating polysulfides. Endowed with a desirable structure and synchronous lithio- and sulfiphilic chemistry, the macro-/mesoporous Co-N-C interface manipulates large polysulfide adsorption uptake, enabling good polysulfide adsorption kinetics, reversible electrocatalysis toward redox of anchored polysulfides, and facile charge transport. It significantly boosts the performance of a simple 70 wt % S/MWCNTs (MWCNTs=multi-walled carbon nanotubes) cathode, achieving high initial capacities (e.g., 1406 mAh g -1 at 0.2C, 1203 mAh g -1 at 1C), nearly 100 % Coulombic efficiencies, and high reversible capacities after cycle tests (e.g., 828.4 mAh g -1 at 1C after 100 cycles) at both low and high current rates. These results demonstrate that decorating separator with macro-/mesoporous Co-N-C paves a feasible way for developing advanced Li-S batteries. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Process and design considerations for high-efficiency solar cells

NASA Technical Reports Server (NTRS)

Rohati, A.; Rai-Choudhury, P.

1985-01-01

This paper shows that oxide surface passivation coupled with optimum multilayer anti-reflective coating can provide approx. 3% (absolute) improvement in solar cell efficiency. Use of single-layer AR coating, without passivation, gives cell efficiencies in the range of 15 to 15.5% on high-quality, 4 ohm-cm as well as 0.1 to 0.2 ohm-cm float-zone silicon. Oxide surface passivation alone raises the cell efficiency to or = 17%. An optimum double-layer AR coating on oxide-passivated cells provides an additional approx. 5 to 10% improvement over a single-layer AR-coated cell, resulting in cell efficiencies in excess of 18%. Experimentally observed improvements are supported by model calculations and an approach to or = 20% efficient cells is discussed.

Advanced Chemical Design for Efficient Lignin Bioconversion

DOE Office of Scientific and Technical Information (OSTI.GOV)

Xie, Shangxian; Sun, Qining; Pu, Yunqiao

Here, lignin depolymerization mainly involves redox reactions relying on the effective electron transfer. Even though electron mediators were previously used for delignification of paper pulp, no study has established a bioprocess to fragment and solubilize the lignin with an effective laccase–mediator system, in particular, for subsequent microbial bioconversion. Efficient lignin depolymerization was achieved by screening proper electron mediators with laccase to attain a nearly 6-fold increase of kraft lignin solubility compared to the control kraft lignin without laccase treatment. Chemical analysis suggested the release of a low molecular weight fraction of kraft lignin into the solution phase. Moreover, NMR analysismore » revealed that an efficient enzyme–mediator system can promote the lignin degradation. More importantly, the fundamental mechanisms guided the development of an efficient lignin bioconversion process, where solubilized lignin from laccase–HBT treatment served as a superior substrate for bioconversion by Rhodococcus opacus PD630. The cell growth was increased by 10 6 fold, and the lipid titer reached 1.02 g/L. Overall, the study has manifested that an efficient enzyme–mediator–microbial system can be exploited to establish a bioprocess to solubilize lignin, cleave lignin linkages, modify the structure, and produce substrates amenable to bioconversion.« less

Advanced Chemical Design for Efficient Lignin Bioconversion

DOE PAGES

Xie, Shangxian; Sun, Qining; Pu, Yunqiao; ...

2017-01-30

Here, lignin depolymerization mainly involves redox reactions relying on the effective electron transfer. Even though electron mediators were previously used for delignification of paper pulp, no study has established a bioprocess to fragment and solubilize the lignin with an effective laccase–mediator system, in particular, for subsequent microbial bioconversion. Efficient lignin depolymerization was achieved by screening proper electron mediators with laccase to attain a nearly 6-fold increase of kraft lignin solubility compared to the control kraft lignin without laccase treatment. Chemical analysis suggested the release of a low molecular weight fraction of kraft lignin into the solution phase. Moreover, NMR analysismore » revealed that an efficient enzyme–mediator system can promote the lignin degradation. More importantly, the fundamental mechanisms guided the development of an efficient lignin bioconversion process, where solubilized lignin from laccase–HBT treatment served as a superior substrate for bioconversion by Rhodococcus opacus PD630. The cell growth was increased by 10 6 fold, and the lipid titer reached 1.02 g/L. Overall, the study has manifested that an efficient enzyme–mediator–microbial system can be exploited to establish a bioprocess to solubilize lignin, cleave lignin linkages, modify the structure, and produce substrates amenable to bioconversion.« less

High Storage Efficiency and Large Fractional Delay of EIT-Based Memory

NASA Astrophysics Data System (ADS)

Chen, Yi-Hsin; Lee, Meng-Jung; Wang, I.-Chung; Du, Shengwang; Chen, Yong-Fan; Chen, Ying-Cheng; Yu, Ite

2013-05-01

In long-distance quantum communication and optical quantum computation, an efficient and long-lived quantum memory is an important component. We first experimentally demonstrated that a time-space-reversing method plus the optimum pulse shape can improve the storage efficiency (SE) of light pulses to 78% in cold media based on the effect of electromagnetically induced transparency (EIT). We obtain a large fractional delay of 74 at 50% SE, which is the best record so far. The measured classical fidelity of the recalled pulse is higher than 90% and nearly independent of the storage time, implying that the optical memory maintains excellent phase coherence. Our results suggest the current result may be readily applied to single-photon quantum states due to quantum nature of the EIT light-matter inference. This study advances the EIT-based quantum memory in practical quantum information applications.

Advanced High Pressure O2/H2 Technology

NASA Technical Reports Server (NTRS)

Morea, S. F. (Editor); Wu, S. T. (Editor)

1985-01-01

Activities in the development of advanced high pressure oxygen-hydrogen stage combustion rocket engines are reported. Particular emphasis is given to the Space Shuttle main engine. The areas of engine technology discussed include fracture and fatigue in engine components, manufacturing and producibility engineering, materials, bearing technology, structure dynamics, fluid dynamics, and instrumentation technology.

Measured impacts of high efficiency domestic clothes washers in a community

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tomlinson, J.; Rizy, T.

1998-07-01

The US market for domestic clothes washers is currently dominated by conventional vertical-axis washers that typically require approximately 40 gallons of water for each wash load. Although the current market for high efficiency clothes washers that use much less water and energy is quite small, it is growing slowly as manufacturers make machines based on tumble action, horizontal-axis designs available and as information about the performance and benefits of such machines is developed and made available to consumers. To help build awareness of these benefits and to accelerate markets for high efficiency washers, the Department of Energy (DOE), under itsmore » ENERGY STAR{reg_sign} Program and in cooperation with a major manufacturers of high efficiency washers, conducted a field evaluation of high efficiency washers using Bern, Kansas as a test bed. Baseline washing machine performance data as well as consumer washing behavior were obtained from data collected on the existing machines of more than 100 participants in this instrumented study. Following a 2-month initial study period, all conventional machines were replaced by high efficiency, tumble-action washers, and the study continued for 3 months. Based on measured data from over 20,000 loads of laundry, the impact of the washer replacement on (1) individual customers` energy and water consumption, (2) customers` laundry habits and perceptions, and (3) the community`s water supply and waste water systems were determined. The study, its findings, and how information from the experiment was used to improve national awareness of high efficiency clothes washer benefits are described in this paper.« less

NASA's Advanced Radioisotope Power Conversion Technology Development Status

NASA Technical Reports Server (NTRS)

Anderson, David J.; Sankovic, John; Wilt, David; Abelson, Robert D.; Fleurial, Jean-Pierre

2007-01-01

NASA's Advanced Radioisotope Power Systems (ARPS) project is developing the next generation of radioisotope power conversion technologies that will enable future missions that have requirements that cannot be met by either photovoltaic systems or by current radioisotope power systems (RPSs). Requirements of advanced RPSs include high efficiency and high specific power (watts/kilogram) in order to meet future mission requirements with less radioisotope fuel and lower mass so that these systems can meet requirements for a variety of future space applications, including continual operation surface missions, outer-planetary missions, and solar probe. These advances would enable a factor of 2 to 4 decrease in the amount of fuel required to generate electrical power. Advanced RPS development goals also include long-life, reliability, and scalability. This paper provides an update on the contractual efforts under the Radioisotope Power Conversion Technology (RPCT) NASA Research Announcement (NRA) for research and development of Stirling, thermoelectric, and thermophotovoltaic power conversion technologies. The paper summarizes the current RPCT NRA efforts with a brief description of the effort, a status and/or summary of the contractor's key accomplishments, a discussion of upcoming plans, and a discussion of relevant system-level benefits and implications. The paper also provides a general discussion of the benefits from the development of these advanced power conversion technologies and the eventual payoffs to future missions (discussing system benefits due to overall improvements in efficiency, specific power, etc.).

High efficiency inductive output tubes with intense annular electron beams

NASA Astrophysics Data System (ADS)

Appanam Karakkad, J.; Matthew, D.; Ray, R.; Beaudoin, B. L.; Narayan, A.; Nusinovich, G. S.; Ting, A.; Antonsen, T. M.

2017-10-01

For mobile ionospheric heaters, it is necessary to develop highly efficient RF sources capable of delivering radiation in the frequency range from 3 to 10 MHz with an average power at a megawatt level. A promising source, which is capable of offering these parameters, is a grid-less version of the inductive output tube (IOT), also known as a klystrode. In this paper, studies analyzing the efficiency of grid-less IOTs are described. The basic trade-offs needed to reach high efficiency are investigated. In particular, the trade-off between the peak current and the duration of the current micro-pulse is analyzed. A particle in the cell code is used to self-consistently calculate the distribution in axial and transverse momentum and in total electron energy from the cathode to the collector. The efficiency of IOTs with collectors of various configurations is examined. It is shown that the efficiency of IOTs can be in the 90% range even without using depressed collectors.

Advanced High-Definition Video Cameras

NASA Technical Reports Server (NTRS)

Glenn, William

2007-01-01

A product line of high-definition color video cameras, now under development, offers a superior combination of desirable characteristics, including high frame rates, high resolutions, low power consumption, and compactness. Several of the cameras feature a 3,840 2,160-pixel format with progressive scanning at 30 frames per second. The power consumption of one of these cameras is about 25 W. The size of the camera, excluding the lens assembly, is 2 by 5 by 7 in. (about 5.1 by 12.7 by 17.8 cm). The aforementioned desirable characteristics are attained at relatively low cost, largely by utilizing digital processing in advanced field-programmable gate arrays (FPGAs) to perform all of the many functions (for example, color balance and contrast adjustments) of a professional color video camera. The processing is programmed in VHDL so that application-specific integrated circuits (ASICs) can be fabricated directly from the program. ["VHDL" signifies VHSIC Hardware Description Language C, a computing language used by the United States Department of Defense for describing, designing, and simulating very-high-speed integrated circuits (VHSICs).] The image-sensor and FPGA clock frequencies in these cameras have generally been much higher than those used in video cameras designed and manufactured elsewhere. Frequently, the outputs of these cameras are converted to other video-camera formats by use of pre- and post-filters.