Science.gov

Sample records for high efficiency fossil

  1. HIGH EFFICIENCY FOSSIL POWER PLANT (HEFPP) CONCEPTUALIZATION PROGRAM

    SciTech Connect

    J.L. Justice

    1999-03-25

    This study confirms the feasibility of a natural gas fueled, 20 MW M-C Power integrated pressurized molten carbonate fuel cell combined in a topping cycle with a gas turbine generator plant. The high efficiency fossil power plant (HEFPP) concept has a 70% efficiency on a LHV basis. The study confirms the HEFPP has a cost advantage on a cost of electricity basis over the gas turbine based combined cycle plants in the 20 MW size range. The study also identifies the areas of further development required for the fuel cell, gas turbine generator, cathode blower, inverter, and power module vessel. The HEFPP concept offers an environmentally friendly power plant with minuscule emission levels when compared with the combined cycle power plant.

  2. High efficiency, quasi-instantaneous steam expansion device utilizing fossil or nuclear fuel as the heat source

    SciTech Connect

    Claudio Filippone, Ph.D.

    1999-06-01

    Thermal-hydraulic analysis of a specially designed steam expansion device (heat cavity) was performed to prove the feasibility of steam expansions at elevated rates for power generation with higher efficiency. The steam expansion process inside the heat cavity greatly depends on the gap within which the steam expands and accelerates. This system can be seen as a miniaturized boiler integrated inside the expander where steam (or the proper fluid) is generated almost instantaneously prior to its expansion in the work-producing unit. Relatively cold water is pulsed inside the heat cavity, where the heat transferred causes the water to flash to steam, thereby increasing its specific volume by a large factor. The gap inside the heat cavity forms a special nozzle-shaped system in which the fluid expands rapidly, accelerating toward the system outlet. The expansion phenomenon is the cause of ever-increasing fluid speed inside the cavity system, eliminating the need for moving parts (pumps, valves, etc.). In fact, the subsequent velocity induced by the sudden fluid expansion causes turbulent conditions, forcing accelerating Reynolds and Nusselt numbers which, in turn, increase the convective heat transfer coefficient. When the combustion of fossil fuels constitutes the heat source, the heat cavity concept can be applied directly inside the stator of conventional turbines, thereby greatly increasing the overall system efficiency.

  3. HIGH EFFICIENCY, QUASI-INSTANTANEOUS STEAM EXPANSION DEVICE UTILIZING FOSSIL OR NUCLEAR FUEL AS THE HEAT SOURCE

    SciTech Connect

    Claudio Filippone, Ph.D.

    1999-06-01

    Thermal-hydraulic analysis of a specially designed steam expansion device (heat cavity) was performed to prove the feasibility of steam expansions at elevated rates for power generation with higher efficiency. The steam expansion process inside the heat cavity greatly depends on the gap within which the steam expands and accelerates. This system can be seen as a miniaturized boiler integrated inside the expander where steam (or the proper fluid) is generated almost instantaneously prior to its expansion in the work-producing unit. Relatively cold water is pulsed inside the heat cavity, where the heat transferred causes the water to flash to steam, thereby increasing its specific volume by a large factor. The gap inside the heat cavity forms a special nozzle-shaped system in which the fluid expands rapidly, accelerating toward the system outlet. The expansion phenomenon is the cause of ever-increasing fluid speed inside the cavity system, eliminating the need for moving parts (pumps, valves, etc.). In fact, the subsequent velocity induced by the sudden fluid expansion causes turbulent conditions, forcing accelerating Reynolds and Nusselt numbers which, in turn, increase the convective heat transfer coefficient. When the combustion of fossil fuels constitutes the heat source, the heat cavity concept can be applied directly inside the stator of conventional turbines, thereby greatly increasing the overall system efficiency.

  4. Krakow clean fossil fuels and energy efficiency project

    SciTech Connect

    Butcher, T.A.; Pierce, B.L.

    1995-12-01

    The Support for Eastern European Democracy (SEED) Act of 1989 directed the U.S. Department of Energy (DOE) to undertake an equipment assessment project aimed at developing the capability within Poland to manufacture or modify industrial-scale combustion equipment to utilize fossil fuels cleanly. This project is being implemented in the city of Krakow as the {open_quotes}Krakow Clean Fossil Fuels and Energy Efficiency Project.{close_quotes} Funding is provided through the U.S. Agency for International Development (AID). The project is being conducted in a manner that can be generalized to all of Poland and to the rest of Eastern Europe. The historic city of Krakow has a population of 750,000. Almost half of the heating energy used in Krakow is supplied by low-efficiency boilerhouses and home coal stoves. Within the town, there are more than 1,300 local boilerhouses and 100, 000 home stoves. These are collectively referred to as the {open_quotes}low emission sources{close_quotes} and they are the primary sources of particulates and hydrocarbon emissions in the city and major contributors of sulfur dioxide and carbon monoxide.

  5. Krakow clean fossil fuels and energy efficiency project

    SciTech Connect

    Pierce, B.L.; Butcher, T.A.

    1994-06-01

    Almost half of the energy used for beating in Krakow is supplied by low-efficiency boilerhouses and home coal stoves. Within the town, there are more than 1,300 boilerhouses with a total capacity of 1,071 MW, and about 100,000 home furnaces with a total capacity of about 300 MW. More than 600 boilerhouses and 60 percent of the home furnaces are situated near the city center. These facilities are referred to as ``low emission sources`` because they have low stacks. They are the primary sources of particulates and hydrocarbons in the city, and major contributors of sulfur dioxide and carbon monoxide. The Support for Eastern European Democracy (SEED) Act of 1989 directed the US Department of Energy (DOE) to undertake an equipment assessment project aimed at developing the capability within Poland to manufacture or modify industrial-scale combustion equipment to utilize fossil fuels cleanly. This project is being implemented in Krakow as the ``Krakow Clean Fossil Fuels and Energy Efficiency Project.`` Funding is provided through the US Agency for International Development (AID). The project is being conducted in a manner that can be generalized to all of Poland and to the rest of Eastern Europe.

  6. Krakow clean fossil fuels and energy efficiency project

    SciTech Connect

    Butcher, T.A.; Pierce, B.L.

    1995-11-01

    The Support for Eastern European Democracy (SEED) Act of 1989 directed the U.S. Department of Energy (DOE) to undertake an equipment assessment project aimed at developing the capability within Poland to manufacture or modify industrial-scale combustion equipment to utilize fossil fuels cleanly. This project is being implemented in the city of Krakow as the `Krakow Clean Fossil Fuels and Energy Efficiency Project.` Funding is provided through the U.S. Agency for International Development (AID). The project is being conducted in a manner that can be generalized to all of Poland and to the rest of Eastern Europe. The historic city of Krakow has a population of 750,000. Almost half of the heating energy used in Krakow is supplied by low-efficiency boilerhouses and home coal stoves. Within the town, there are more than 1,300 local boilerhouses and 100,000 home stoves. These are collectively referred to as the `low emission sources` and they are the primary sources of particulates and hydrocarbon emissions in the city and major contributors of sulfur dioxide and carbon monoxide.

  7. Krakow Clean Fossil Fuels and Energy Efficiency Program

    SciTech Connect

    Butcher, T.; Pierce, B.; Krishna, C.R.

    1992-09-01

    The Support for Eastern European Democracy (SEED) Act of 1989 directed the US Department of Energy (DOE) to undertake an equipment assessment project aimed at developing the capability within Poland to manufacture or modify industrial-scale combustion equipment to utilize fossil fuels cleanly. The project is being conducted in three phases. In Phase I, testing and analytical activities will establish the current level of emissions from existing equipment and operating practices, and will provide estimates of the costs and emission reductions of various options. Phase II consists of a series of public meetings in both Poland and the United States to present the results of Phase I activities. In Phase III, DOE will issue a solicitation for Polish/US joint ventures to perform commercial feasibility studies for the use of US technology in one or more of the areas under consideration. This report provides interim results from Phase 1.

  8. Krakow Clean Fossil Fuels and Energy Efficiency Project

    SciTech Connect

    Butcher, T.A.; Pierce, B.; Krajewski, R.; LaMontagne, J.; Kirchstetter, T.

    1992-05-01

    In Karkow, Poland almost half of the energy used for heating is supplied by local, solid-fuel-fired boilerhouses and home stoves. These facilities are referred to as the low emission sources'' and are primary contributors of particulates and hydrocarbon air pollution in the city and secondary contributors of sulfur dioxide and carbon monoxide. The Support of Eastern European Democracy Act of 1989 directed the US Department of Energy to undertake an equipment assessment project aimed at developing the capability within Poland to manufacture or modify industrial-scale combustion equipment to utilize fossil fuels cleanly. The Project is being conducted in a manner that can be generalized to all of Poland and uito the rest of Eastern Europe. The project plan includes three phases which have been developed around five specific subprojects. In Phase 1, technical and economic assessments will be made of pollution reduction options for the five subprojects. Phase 2 plans call for public meetings in the US and Poland for companies interested in forming joint ventures. Information will be available in these meetings to enable companies to identify markets and select potential partners that meet with their capabilities and interests. In Phase 3, DOE will issue a solicitation for Polish/American joint ventures to perform commercial feasibility studies for the supply of US technology applicable to one or more of the five subprojects. The selected joint venture companies would receive assistance in the form of cooperative agreements requiring at least 50% cost-sharing to perform those activities necessary to permit them to conduct business in Poland.

  9. Krakow Clean Fossil Fuels and Energy Efficiency Project

    SciTech Connect

    Butcher, T.A.; Pierce, B.; Krajewski, R.; LaMontagne, J.; Kirchstetter, T.

    1992-05-01

    In Karkow, Poland almost half of the energy used for heating is supplied by local, solid-fuel-fired boilerhouses and home stoves. These facilities are referred to as the ``low emission sources`` and are primary contributors of particulates and hydrocarbon air pollution in the city and secondary contributors of sulfur dioxide and carbon monoxide. The Support of Eastern European Democracy Act of 1989 directed the US Department of Energy to undertake an equipment assessment project aimed at developing the capability within Poland to manufacture or modify industrial-scale combustion equipment to utilize fossil fuels cleanly. The Project is being conducted in a manner that can be generalized to all of Poland and uito the rest of Eastern Europe. The project plan includes three phases which have been developed around five specific subprojects. In Phase 1, technical and economic assessments will be made of pollution reduction options for the five subprojects. Phase 2 plans call for public meetings in the US and Poland for companies interested in forming joint ventures. Information will be available in these meetings to enable companies to identify markets and select potential partners that meet with their capabilities and interests. In Phase 3, DOE will issue a solicitation for Polish/American joint ventures to perform commercial feasibility studies for the supply of US technology applicable to one or more of the five subprojects. The selected joint venture companies would receive assistance in the form of cooperative agreements requiring at least 50% cost-sharing to perform those activities necessary to permit them to conduct business in Poland.

  10. Direct Carbon Conversion: Application to the Efficient Conversion of Fossil Fuels to Electricity

    SciTech Connect

    Cooper, J F; Cherepy, N; Berry, G; Pasternak, A; Surles, T; Steinberg, M

    2001-03-07

    We introduce a concept for efficient conversion of fossil fuels to electricity that entails the decomposition of fossil-derived hydrocarbons into carbon and hydrogen, and electrochemical conversion of these fuels in separate fuel cells. Carbon/air fuel cells have the advantages of near zero entropy change and associated heat production (allowing 100% theoretical conversion efficiency). The activities of the C fuel and CO{sub 2} product are invariant, allowing constant EMF and full utilization of fuel in single pass mode of operation. System efficiency estimates were conducted for several routes involving sequential extraction of a hydrocarbon from the fossil resource by (hydro) pyrolysis followed by thermal decomposition. The total energy conversion efficiencies of the processes were estimated to be (1) 80% for direct conversion of petroleum coke; (2) 67% HHV for CH{sub 4}; (3) 72% HHV for heavy oil (modeled using properties of decane); (4) 75.5% HHV (83% LHV) for natural gas conversion with a Rankine bottoming cycle for the H{sub 2} portion; and (5) 69% HHV for conversion of low rank coals and lignite through hydrogenation and pyrolysis of the CH{sub 4} intermediate. The cost of carbon fuel is roughly $7/GJ, based on the cost of the pyrolysis step in the industrial furnace black process. Cell hardware costs are estimated to be less than $500/kW.

  11. Stable carbon isotope ratios and intrinsic water-use efficiency of Miocene fossil leaves compared to modern congeners

    SciTech Connect

    Marshall, J.D.; Zhang, J.; Rember, W.C.; Jennings, D.; Larson, P. )

    1994-06-01

    Miocene fossil leaves of forest trees were extracted from the Clarkia, Idaho fossil beds and their stable carbon isotope ratios were analyzed. Fossils had higher lignin concentrations and lower cellulose concentrations that modern leaves due to diagenesis and the HF used to extract the fossils. Therefore, [delta][sup 13]C of extracted fossil lignin was compared to that of modern lignin. Fossil lignin [delta][sup 13]C was significantly different from that of congeneric modern leaves (paired t-test, P<0.0001), but was 1.9% less negative. Gymnosperms (Metasequoia, Taxodium) were less negative than angiosperms (e.g., Magnolia, Quercus, Acer, Persea), but no difference between evergreen and deciduous species was detected. Using published estimates of the concentration and [delta][sup 13]C of atmospheric CO[sub 2] during the Miocene was estimated the CO[sub 2] partial pressure gradient across the stomata (intrinsic water-use efficiency). Intrinsic water-use efficiency was at least 70% higher during this past [open quotes]greenhouse[close quotes] period than at present.

  12. High efficiency incandescent lighting

    SciTech Connect

    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.

  13. High Efficiency Cell Development

    NASA Technical Reports Server (NTRS)

    Carbajal, B. G.

    1979-01-01

    The specific activity was to improve the tandem junction Cell (TJC) as a high efficiency solar cell. The TJC development was to be consistent with module assembly and should contribute to the overall goals of the Low-Cost Solar Array Project. During 1978, TJC efficiency improved from approximately 11 percent to approximately 16 percent (AMI). Photogenerated current densities in excess of 42 mA/sq cm were observed at AMO. Open circuit voltages as high as 0.615 V were measured at AMO. Fill factor was only 0.68 - 0.75 due to a nonoptimum metal contact design. A device model was conceived in which the solar cell is modelled as a transitor. There are virtually no interconnect or packaging factor systems and the TJC is compatible with all conventional module fabrication systems. A modification of the TJC, the Front Surface Field (FSF) cell, was also explored.

  14. High Efficiency, Clean Combustion

    SciTech Connect

    Donald Stanton

    2010-03-31

    Energy use in trucks has been increasing at a faster rate than that of automobiles within the U.S. transportation sector. According to the Energy Information Administration (EIA) Annual Energy Outlook (AEO), a 23% increase in fuel consumption for the U.S. heavy duty truck segment is expected between 2009 to 2020. The heavy duty vehicle oil consumption is projected to grow between 2009 and 2050 while light duty vehicle (LDV) fuel consumption will eventually experience a decrease. By 2050, the oil consumption rate by LDVs is anticipated to decrease below 2009 levels due to CAFE standards and biofuel use. In contrast, the heavy duty oil consumption rate is anticipated to double. The increasing trend in oil consumption for heavy trucks is linked to the vitality, security, and growth of the U.S. economy. An essential part of a stable and vibrant U.S. economy is a productive U.S. trucking industry. Studies have shown that the U.S. gross domestic product (GDP) is strongly correlated to freight transport. Over 90% of all U.S. freight tonnage is transported by diesel power and over 75% is transported by trucks. Given the vital role that the trucking industry plays in the economy, improving the efficiency of the transportation of goods was a central focus of the Cummins High Efficient Clean Combustion (HECC) program. In a commercial vehicle, the diesel engine remains the largest source of fuel efficiency loss, but remains the greatest opportunity for fuel efficiency improvements. In addition to reducing oil consumption and the dependency on foreign oil, this project will mitigate the impact on the environment by meeting US EPA 2010 emissions regulations. Innovation is a key element in sustaining a U.S. trucking industry that is competitive in global markets. Unlike passenger vehicles, the trucking industry cannot simply downsize the vehicle and still transport the freight with improved efficiency. The truck manufacturing and supporting industries are faced with numerous

  15. 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.

  16. 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.

  17. 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.

  18. Development of high temperature air combustion technology in pulverized fossil fuel fired boilers

    SciTech Connect

    Hai Zhang; Guangxi Yue; Junfu Lu; Zhen Jia; Jiangxiong Mao; Toshiro Fujimori; Toshiyuki Suko; Takashi Kiga

    2007-07-01

    High temperature air combustion (HTAC) is a promising technology for energy saving, flame stability enhancement and NOx emission reduction. In a conventional HTAC system, the combustion air is highly preheated by using the recuperative or regenerative heat exchangers. However, such a preheating process is difficult to implement for pulverized fossil fuel fired boilers. In this paper, an alternative approach is proposed. In the proposed HTAC system, a special burner, named PRP burner is introduced to fulfill the preheating process. The PRP burner has a preheating chamber with one end connected with the primary air and the other end opened to the furnace. Inside the chamber, gas recirculation is effectively established such that hot flue gases in the furnace can be introduced. Combustible mixture instead of combustion air is highly preheated by the PRP burner. A series of experiments have been conducted in an industrial scale test facility, burning low volatile petroleum coke and an anthracite coal. Stable combustion was established for burning pure petroleum coke and anthracite coal, respectively. Inside the preheating chamber, the combustible mixture was rapidly heated up to a high temperature level close to that of the hot secondary air used in the conventional HTAC system. The rapid heating of the combustible mixture in the chamber facilitates pyrolysis, volatile matter release processes for the fuel particles, suppressing ignition delay and enhancing combustion stability. Moreover, compared with the results measured in the same facility but with a conventional low NOx burner, NOx concentration at the furnace exit was at the same level when petroleum coke was burnt and 50% less when anthracite was burnt. Practicability of the HTAC technology using the proposed approach was confirmed for efficiently and cleanly burning fossil fuels. 16 refs., 10 figs., 1 tab.

  19. HIGH EFFICIENCY SYNGAS GENERATION

    SciTech Connect

    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 and 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 tested the

  20. High-efficiency CARM

    SciTech Connect

    Bratman, V.L.; Kol`chugin, B.D.; Samsonov, S.V.; Volkov, A.B.

    1995-12-31

    The Cyclotron Autoresonance Maser (CARM) is a well-known variety of FEMs. Unlike the ubitron in which electrons move in a periodical undulator field, in the CARM the particles move along helical trajectories in a uniform magnetic field. Since it is much simpler to generate strong homogeneous magnetic fields than periodical ones for a relatively low electron energy ({Brit_pounds}{le}1-3 MeV) the period of particles` trajectories in the CARM can be sufficiently smaller than in the undulator in which, moreover, the field decreases rapidly in the transverse direction. In spite of this evident advantage, the number of papers on CARM is an order less than on ubitron, which is apparently caused by the low (not more than 10 %) CARM efficiency in experiments. At the same time, ubitrons operating in two rather complicated regimes-trapping and adiabatic deceleration of particles and combined undulator and reversed guiding fields - yielded efficiencies of 34 % and 27 %, respectively. The aim of this work is to demonstrate that high efficiency can be reached even for a simplest version of the CARM. In order to reduce sensitivity to an axial velocity spread of particles, a short interaction length where electrons underwent only 4-5 cyclotron oscillations was used in this work. Like experiments, a narrow anode outlet of a field-emission electron gun cut out the {open_quotes}most rectilinear{close_quotes} near-axis part of the electron beam. Additionally, magnetic field of a small correcting coil compensated spurious electron oscillations pumped by the anode aperture. A kicker in the form of a sloping to the axis frame with current provided a control value of rotary velocity at a small additional velocity spread. A simple cavity consisting of a cylindrical waveguide section restricted by a cut-off waveguide on the cathode side and by a Bragg reflector on the collector side was used as the CARM-oscillator microwave system.

  1. High-Temperature Corrosion in Fossil Fuel Power Generation: Present and Future

    NASA Astrophysics Data System (ADS)

    Pint, B. A.

    2013-08-01

    Fossil fuels have historically represented two-thirds of all electricity generation in the United States and are projected to continue to play a similar role despite historically low projected growth rates in electricity demand and the recent dramatic shift from coal to more natural gas usage. Economic and environmental drivers will require more reliable and efficient fossil fuel generation systems in the future, likely with new system designs, higher operating temperatures, and more aggressive environments. Some of the current corrosion issues in power plants are reviewed along with research on materials solutions for systems envisioned for the near future, such as coal gasification and oxy-fired coal boilers.

  2. High Efficiency Integrated Package

    SciTech Connect

    Ibbetson, James

    2013-09-15

    Solid-state lighting based on LEDs has emerged as a superior alternative to inefficient conventional lighting, particularly incandescent. LED lighting can lead to 80 percent energy savings; can last 50,000 hours – 2-50 times longer than most bulbs; and contains no toxic lead or mercury. However, to enable mass adoption, particularly at the consumer level, the cost of LED luminaires must be reduced by an order of magnitude while achieving superior efficiency, light quality and lifetime. To become viable, energy-efficient replacement solutions must deliver system efficacies of ≥ 100 lumens per watt (LPW) with excellent color rendering (CRI > 85) at a cost that enables payback cycles of two years or less for commercial applications. This development will enable significant site energy savings as it targets commercial and retail lighting applications that are most sensitive to the lifetime operating costs with their extended operating hours per day. If costs are reduced substantially, dramatic energy savings can be realized by replacing incandescent lighting in the residential market as well. In light of these challenges, Cree proposed to develop a multi-chip integrated LED package with an output of > 1000 lumens of warm white light operating at an efficacy of at least 128 LPW with a CRI > 85. This product will serve as the light engine for replacement lamps and luminaires. At the end of the proposed program, this integrated package was to be used in a proof-of-concept lamp prototype to demonstrate the component’s viability in a common form factor. During this project Cree SBTC developed an efficient, compact warm-white LED package with an integrated remote color down-converter. Via a combination of intensive optical, electrical, and thermal optimization, a package design was obtained that met nearly all project goals. This package emitted 1295 lm under instant-on, room-temperature testing conditions, with an efficacy of 128.4 lm/W at a color temperature of ~2873

  3. Late Cretaceous Extreme Polar Warmth recorded by Vertebrate Fossils from the High Canadian Arctic

    NASA Astrophysics Data System (ADS)

    Vandermark, D.; Tarduno, J. A.; Brinkman, D.

    2006-12-01

    A vertebrate fossil assemblage from Late Cretaceous (Coniacian-Turonian, ~92 to 86 Ma) rocks on Axel Heiberg Island in the High Canadian Arctic reflects what was once a diverse community of freshwater fishes and reptiles. Paleomagnetic data indicate a paleolatitude of ~71° N for the site; the fossils are from non-migratory fauna, so they can provide insight into Late Cretaceous polar climate. The fossil assemblage includes large (> 2.4 m long) champsosaurs (extinct crocodilelike reptiles). The presence of large champsosaurs suggests a mean annual temperature > 14 °C (and perhaps as great as 25 °C). Here we summarize findings and analyses following the discovery of the fossil-bearing strata in 1996. Examination of larger fish elements, isolated teeth and SEM studies of microstructures indicates the presence of lepisosteids, amiids and teleosts (Friedman et al., 2003) Interestingly, the only other known occurrence of amiids and lepisosteids, fossil or recent, are from intervals of extreme warmth during the Tertiary. Turtles present in the assemblage include Boreralochelys axelheibergensis, a generically indeterminate eucryptodire and a trioychid (Brinkman and Tarduno, 2005). The level of turtle diversity is also comparable to mid-latitude assemblages with a mean annual paleotemperature of at least 14 °C. A large portion of the champsosaur fossil assemblage is comprised of elements from subadults. This dominance of subadults is similar to that seen from low latitude sites. Because of the sensitivity of juveniles to ice formation, the make-up of the Arctic champsosaur population further indicates that the Late Cretaceous saw an interval of extreme warmth and low seasonality. We note the temporal coincidence of these fossils with volcanism at large igneous provinces (including high Arctic volcanism) and suggest that a pulse in volcanic carbon dioxide emissions helped cause the global warmth.

  4. NOVEL GAS SENSORS FOR HIGH-TEMPERATURE FOSSIL FUEL APPLICATIONS

    SciTech Connect

    Palitha Jayaweera

    2004-05-01

    SRI is developing ceramic-based microsensors for detection of exhaust gases such as NO, NO{sub 2}, and CO in advanced combustion and gasification systems. The sensors detect the electrochemical activity of the exhaust gas species on catalytic electrodes and are designed to operate at high temperatures, elevated pressures, and corrosive environments typical of large power generation exhausts. Under this research project we are developing sensors for multiple gas detection in a single package along with data acquisition and control software and hardware. The sensor package can be easily integrated into online monitoring systems for active emission control. This report details the research activities performed from October 2003 to April 2004.

  5. NOVEL GAS SENSORS FOR HIGH-TEMPERATURE FOSSIL FUEL APPLICATIONS

    SciTech Connect

    Palitha Jayaweera

    2004-05-01

    SRI is developing ceramic-based microsensors for detection of exhaust gases such as NO, NO{sub 2}, and CO in advanced combustion and gasification systems. The sensors detect the electrochemical activity of the exhaust gas species on catalytic electrodes and are designed to operate at high temperatures, elevated pressures, and corrosive environments typical of large power generation exhausts. Under this research project we are developing sensors for multiple gas detection in a single package along with data acquisition and control software and hardware. The sensor package can be easily integrated into online monitoring systems for active emission control. This report details the research activities performed from May 2004 to October 2004 including testing of catalytic materials, sensor design and fabrication, and software development.

  6. Novel Gas Sensors for High-Temperature Fossil Fuel Applications

    SciTech Connect

    Palitha Jayaweera; Francis Tanzella

    2005-03-01

    SRI International (SRI) is developing ceramic-based microsensors to detect exhaust gases such as NO, NO{sub 2}, and CO in advanced combustion and gasification systems under this DOE NETL-sponsored research project. The sensors detect the electrochemical activity of the exhaust gas species on catalytic electrodes attached to a solid state electrolyte and are designed to operate at the high temperatures, elevated pressures, and corrosive environments typical of large power generation exhausts. The sensors can be easily integrated into online monitoring systems for active emission control. The ultimate objective is to develop sensors for multiple gas detection in a single package, along with data acquisition and control software and hardware, so that the information can be used for closed-loop control in novel advanced power generation systems. This report details the Phase I Proof-of-Concept, research activities performed from October 2003 to March 2005. SRI's research work includes synthesis of catalytic materials, sensor design and fabrication, software development, and demonstration of pulse voltammetric analysis of NO, NO{sub 2}, and CO gases on catalytic electrodes.

  7. High efficiency furnace

    SciTech Connect

    Hwang, K. S.; Koestler, D. J.

    1985-12-31

    Disclosed is a dwelling furnace having at least one clam-shell type primary heat exchanger in parallel orientation with a secondary heat exchanger, both the primary and secondary heat exchangers being vertically oriented relative to a furnace housing and parallel to the flow of air to be heated. The primary heat exchanger has a combustion chamber in the lower end thereof, and the lower end of the secondary heat exchanger exhausts into a tertiary heat exchanger oriented approximately perpendicular to the primary and secondary heat exchangers and horizontally relative to the housing, below the combustion chambers of the primary heat exchangers and below the exhaust outlet of the secondary heat exchanger. The tertiary heat exchanger includes a plurality of condensation tubes for retrieving the latent heat of condensation of the combustion gases. The furnace further comprises an induced draft blower for drawing combustion gases through the heat exchangers and inducting sufficient air to the combustion chamber of the primary heat exchanger for efficient combustion.

  8. High efficiency gas burner

    DOEpatents

    Schuetz, Mark A.

    1983-01-01

    A burner assembly provides for 100% premixing of fuel and air by drawing the air into at least one high velocity stream of fuel without power assist. Specifically, the nozzle assembly for injecting the fuel into a throat comprises a plurality of nozzles in a generally circular array. Preferably, swirl is imparted to the air/fuel mixture by angling the nozzles. The diffuser comprises a conical primary diffuser followed by a cusp diffuser.

  9. High resolution fossil fuel combustion CO2 emission fluxes for the United States

    SciTech Connect

    Gurney, Kevin R.; Mendoza, Daniel L.; Zhou, Yuyu; Fischer, Marc L.; Miller, Chris C.; Geethakumar, Sarath; de la Rue du Can, Stephane

    2009-03-19

    Quantification of fossil fuel CO{sub 2} emissions at fine space and time resolution is emerging as a critical need in carbon cycle and climate change research. As atmospheric CO{sub 2} measurements expand with the advent of a dedicated remote sensing platform and denser in situ measurements, the ability to close the carbon budget at spatial scales of {approx}100 km{sup 2} and daily time scales requires fossil fuel CO{sub 2} inventories at commensurate resolution. Additionally, the growing interest in U.S. climate change policy measures are best served by emissions that are tied to the driving processes in space and time. Here we introduce a high resolution data product (the 'Vulcan' inventory: www.purdue.edu/eas/carbon/vulcan/) that has quantified fossil fuel CO{sub 2} emissions for the contiguous U.S. at spatial scales less than 100 km{sup 2} and temporal scales as small as hours. This data product, completed for the year 2002, includes detail on combustion technology and 48 fuel types through all sectors of the U.S. economy. The Vulcan inventory is built from the decades of local/regional air pollution monitoring and complements these data with census, traffic, and digital road data sets. The Vulcan inventory shows excellent agreement with national-level Department of Energy inventories, despite the different approach taken by the DOE to quantify U.S. fossil fuel CO{sub 2} emissions. Comparison to the global 1{sup o} x 1{sup o} fossil fuel CO{sub 2} inventory, used widely by the carbon cycle and climate change community prior to the construction of the Vulcan inventory, highlights the space/time biases inherent in the population-based approach.

  10. High resolution fossil fuel combustion CO{sub 2} emission fluxes for the United States

    SciTech Connect

    Kevin R. Gurney; Daniel L. Mendoza; Yuyu Zhou; Marc L. Fischer; Chris C. Miller; Sarath Geethakumar; Stephane de la Rue du Can

    2009-07-15

    Quantification of fossil fuel CO{sub 2} emissions at fine space and time resolution is emerging as a critical need in carbon cycle and climate change research. As atmospheric CO{sub 2} measurements expand with the advent of a dedicated remote sensing platform and denser in situ measurements, the ability to close the carbon budget at spatial scales of about 100 km{sup 2} and daily time scales requires fossil fuel CO{sub 2} inventories at commensurate resolution. Additionally, the growing interest in U.S. climate change policy measures are best served by emissions that are tied to the driving processes in space and time. Here we introduce a high resolution data product (the 'Vulcan' inventory: www.purdue.edu/eas/carbon/vulcan/) that has quantified fossil fuel CO{sub 2} emissions for the contiguous U.S. at spatial scales less than 100 km{sup 2} and temporal scales as small as hours. This data product, completed for the year 2002, includes detail on combustion technology and 48 fuel types through all sectors of the U.S. economy. The Vulcan inventory is built from the decades of local/regional air pollution monitoring and complements these data with census, traffic, and digital road data sets. The Vulcan inventory shows excellent agreement with national-level Department of Energy inventories, despite the different approach taken by the DOE to quantify U.S. fossil fuel CO{sub 2} emissions. Comparison to the global 1{sup o} x 1{sup o} fossil fuel CO{sub 2} inventory, used widely by the carbon cycle and climate change community prior to the construction of the Vulcan inventory, highlights the space/time biases inherent in the population-based approach. 39 refs., 5 figs., 1 tab.

  11. High resolution fossil fuel combustion CO2 emission fluxes for the United States.

    PubMed

    Gurney, Kevin R; Mendoza, Daniel L; Zhou, Yuyu; Fischer, Marc L; Miller, Chris C; Geethakumar, Sarath; de la Rue du Can, Stephane

    2009-07-15

    Quantification of fossil fuel CO2 emissions at fine space and time resolution is emerging as a critical need in carbon cycle and climate change research. As atmospheric CO2 measurements expand with the advent of a dedicated remote sensing platform and denser in situ measurements, the ability to close the carbon budget at spatial scales of approximately 100 km2 and daily time scales requires fossil fuel CO2 inventories at commensurate resolution. Additionally, the growing interest in U.S. climate change policy measures are best served by emissions that are tied to the driving processes in space and time. Here we introduce a high resolution data product (the "Vulcan" inventory: www.purdue.edu/eas/carbon/vulcan/) that has quantified fossil fuel CO2 emissions for the contiguous U.S. at spatial scales less than 100 km2 and temporal scales as small as hours. This data product completed for the year 2002, includes detail on combustion technology and 48 fuel types through all sectors of the U.S. economy. The Vulcan inventory is built from the decades of local/regional air pollution monitoring and complements these data with census, traffic, and digital road data sets. The Vulcan inventory shows excellent agreement with national-level Department of Energy inventories, despite the different approach taken by the DOE to quantify U.S. fossil fuel CO2 emissions. Comparison to the global 1degree x 1 degree fossil fuel CO2 inventory, used widely by the carbon cycle and climate change community prior to the construction of the Vulcan inventory, highlights the space/time biases inherent in the population-based approach.

  12. High efficiency centrifugal pump

    SciTech Connect

    Nasvytis, P.J.; Jahrstorfer, G.W.

    1983-10-11

    A high speed fuel pump for a gas turnbine engine has a positively-driven shroud positioned between a main impeller and the wall of a pumping cavity to reduce impeller drag. The shroud is formed by a first disc having a boost impeller connected to its central hub portion and a second disc having a gear carried by its central hub portion. The main drive shaft assembly to which the main impeller is connected, carries a gear which meshes with gear mounted upon a shaft. The shaft also carries a gear which meshes with the gear. The gears are sized so that the shroud is driven at one-half the speed of the main impeller in order to maximize impeller drag reduction and enhance pumping capability when severe inlet conditions are present at the pump inlet.

  13. Filed-Analog Study: Efficiency of microbial fossilization in sulfate-rich playas

    NASA Astrophysics Data System (ADS)

    Glamoclija, M.; Zeidan, M.; Potochniak, S.

    2015-12-01

    The samples with the highest priority for sample return will be samples that contain potential life signatures. Sulfate-rich salts have been identified as important component of Mars sedimentary deposits, illustrating the importance of near-surface hydrological processes during the planet's history. The presence of Noachian/early Hesperian sulfate-rich deposits have been identified by the MER's Opportunity at Meridiani Planum and by MRO mission in sedimentary sequences within Gale crater, the Mars Science Laboratory landing site. White Sands National Monument, which we are using as a terrestrial analog in our study, holds active playas that may contain different sizes of water bodies during the year. Alkali Flat contains also preserved deposits of Pleistocene Lake Otero. The presence of a range of modern playas and equivalent Pleistocene deposits allows for an excellent comparison of these different extreme transitional habitats and potential of preservation of organics in an evaporitic playa setting. We have performed shallow drilling (1m) of the Lake Lucero deposits and of Lake Otero evaporitic sequence. The XRD analysis revealed that samples are mainly composed of gypsum and minor mineral phases as brushite, halite and quartz. SEM/EDS revealed the presence of amorphous phases such as halite, glauberite, magnesium chlorite salt, and diatom shells and biofilm. Biofilm is found in near surface samples, which may be attributed to microbial adaptation to desert environment and considered as one of the characteristics of modern and not fossil microbial communities. The compositional difference of salt precipitates associated with potentially geologically old biofilm and the modern counterpart are still ongoing and our findings will be presented at the conference. Further, comparison of environmental physicochemical conditions and molecular biology will be used to determine the characteristics of modern microbial habitats/deposits and to attempt to distinguish them

  14. Direct electrochemical conversion of carbon: systems for efficient conversion of fossil fuels to electricity

    SciTech Connect

    Cooper, J F; Cherepy, N; Krueger, R

    2000-08-10

    The direct electrochemical conversion of carbon involves discharge of suspensions of reactive carbon particles in a molten salt electrolyte against an oxygen (air) cathode. (Figure 1). The free energy and the enthalpy of the oxidation reaction are nearly identical. This allows theoretical efficiencies ({Delta}G(T)/{Delta}H) to approach 100% at temperatures from 500 to 800 C. Entropy heat losses are therefore negligible. The activities of the elemental carbon and of the carbon dioxide product are uniform throughout the fuel cell and constant over discharge time. This stabilizes cell EMF and allows full utilization of the carbon fuel in a single pass. Finally, the energy cost for pyrolysis of hydrocarbons is generally very low compared with that of steam reforming or water gas reactions. Direct electrochemical conversion of carbon might be compared with molten carbonate fuel cell using carbon rather than hydrogen. However, there are important differences. There is no hydrogen involved (except from trace water contamination). The mixture of molten carbonate and carbon is not highly flammable. The carbon is introduced in as a particulate, rather than as a high volume flow of hydrogen. At the relatively low rates of discharge (about 1 kA/m{sup 2}), the stoichiometric requirements for carbon dioxide by the cathodic reaction may be met by diffusion across the thin electrolyte gap. We report recent experimental work at LLNL using melt slurries of reactive carbons produced by the thermal decomposition of hydrocarbons. We have found that anodic reactivity of carbon in mixed carbonate melts depends strongly on form, structure and nano-scale disorder of the materials, which are fixed by the hydrocarbon starting material and the conditions of pyrolysis. Thus otherwise chemically pure carbons made by hydrocarbon pyrolysis show rates at fixed potentials that span an order of magnitude, while this range lies 1-2 orders of magnitude higher than the current density of graphite plate

  15. High efficiency solar cell processing

    NASA Technical Reports Server (NTRS)

    Ho, F.; Iles, P. A.

    1985-01-01

    At the time of writing, cells made by several groups are approaching 19% efficiency. General aspects of the processing required for such cells are discussed. Most processing used for high efficiency cells is derived from space-cell or concentrator cell technology, and recent advances have been obtained from improved techniques rather than from better understanding of the limiting mechanisms. Theory and modeling are fairly well developed, and adequate to guide further asymptotic increases in performance of near conventional cells. There are several competitive cell designs with promise of higher performance ( 20%) but for these designs further improvements are required. The available cell processing technology to fabricate high efficiency cells is examined.

  16. Advanced high efficiency concentrator cells

    SciTech Connect

    Gale, R. . Varian Research Center)

    1992-06-01

    This report describes research to develop the technology needed to demonstrate a monolithic, multijunction, two-terminal, concentrator solar cell with a terrestrial power conversion efficiency greater than 35%. Under three previous subcontracts, Varian developed many of the aspects of a technology needed to fabricate very high efficiency concentrator cells. The current project was aimed at exploiting the new understanding of high efficiency solar cells. Key results covered in this report are as follows. (1) A 1.93-eV AlGaAs/1.42-eV GaAs metal-interconnected cascade cell was manufactured with a one-sun efficiency at 27.6% at air mass 1.5 (AM1.5) global. (2) A 1.0eV InGaAs cell was fabricated on the reverse'' side of a low-doped GaAs substrate with a one-sun efficiency of 2.5% AM1.5 diffuse and a short-circuit current of 14.4 mA/cm{sup 2}. (3) Small-scale manufacturing of GaAs p/n concentrator cells was attempted and obtained an excellent yield of high-efficiency cells. (4) Grown-in tunnel junction cell interconnects that are transparent and thermally stable using C and Si dopants were developed. 10 refs.

  17. A Model of Carbon Capture and Storage with Demonstration of Global Warming Potential and Fossil Fuel Resource Use Efficiency

    NASA Astrophysics Data System (ADS)

    Suebsiri, Jitsopa

    Increasing greenhouse gas concentration in the atmosphere influences global climate change even though the level of impact is still unclear. Carbon dioxide capture and storage (CCS) is increasingly seen as an important component of broadly based greenhouse gas reduction measures. Although the other greenhouse gases are more potent, the sheer volume of CO 2 makes it dominant in term of its effect in the atmosphere. To understand the implications, CCS activities should be studied from a full life cycle perspective. This thesis outlines the successful achievement of the objectives of this study in conducting life cycle assessment (LCA), reviewing the carbon dioxide implications only, combining two energy systems, coal-fired electrical generations and CO2 used for enhanced oil recovery (EOR). LCA is the primary approach used in this study to create a tool for CCS environmental evaluation. The Boundary Dam Power Station (BDPS) and the Weyburn-Midale CO 2 EOR Project in Saskatchewan, Canada, are studied and adopted as case scenarios to find the potential for effective application of CCS in both energy systems. This study demonstrates two levels of retrofitting of the BDPS, retrofit of unit 3 or retrofit of all units, combined with three options for CO 2 geological storage: deep saline aquifer, CO2 EOR, and a combination of deep saline aquifer storage and CO2 EOR. Energy output is considered the product of combining these two energy resources (coal and oil). Gigajoules (GJ) are used as the fundamental unit of measurement in comparing the combined energy types. The application of this tool effectively demonstrates the results of application of a CCS system concerning global warming potential (GWP) and fossil fuel resource use efficiency. Other environmental impacts could be analyzed with this tool as well. In addition, the results demonstrate that the GWP reduction is directly related to resource use efficiency. This means the lower the GWP of CCS, the lower resource use

  18. High efficiency solar panel /HESP/

    NASA Technical Reports Server (NTRS)

    Stella, P. M.; Gay, C.; Uno, F.; Scott-Monck, J.

    1978-01-01

    A family of high efficiency, weldable silicon solar cells, incorporating nearly every feature of advanced cell technology developed in the past four years, was produced and subjected to space qualification testing. This matrix contained both field and non-field cells ranging in thickness from 0.10 mm to 0.30 mm, and in base resistivity from nominal two to one hundred ohm-cm. Initial power outputs as high as 20 mW/sq cm (14.8% AM0 efficiency) were produced by certain cell types within the matrix.

  19. High Efficiency Engine Technologies Program

    SciTech Connect

    Rich Kruiswyk

    2010-07-13

    Caterpillar's Product Development and Global Technology Division carried out a research program on waste heat recovery with support from DOE (Department of Energy) and the DOE National Energy Technology Laboratory. The objective of the program was to develop a new air management and exhaust energy recovery system that would demonstrate a minimum 10% improvement in thermal efficiency over a base heavy-duty on-highway diesel truck engine. The base engine for this program was a 2007 C15 15.2L series-turbocharged on-highway truck engine with a LPL (low-pressure loop) exhaust recirculation system. The focus of the program was on the development of high efficiency turbomachinery and a high efficiency turbocompound waste heat recovery system. The focus of each area of development was as follows: (1) For turbine stages, the focus was on investigation and development of technologies that would improve on-engine exhaust energy utilization compared to the conventional radial turbines in widespread use today. (2) For compressor stages, the focus was on investigating compressor wheel design parameters beyond the range typically utilized in production, to determine the potential efficiency benefits thereof. (3) For turbocompound, the focus was on the development of a robust bearing system that would provide higher bearing efficiencies compared to systems used in turbocompound power turbines in production. None of the turbocharger technologies investigated involved addition of moving parts, actuators, or exotic materials, thereby increasing the likelihood of a favorable cost-value tradeoff for each technology. And the turbocompound system requires less hardware addition than competing bottoming cycle technologies, making it a more attractive solution from a cost and packaging standpoint. Main outcomes of the program are as follows: (1) Two turbine technologies that demonstrated up to 6% improvement in turbine efficiency on gas stand and 1-3% improvement in thermal efficiency in

  20. Enabling High Efficiency Ethanol Engines

    SciTech Connect

    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 is 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.

  1. The Unusually High Halo Concentration of the Fossil Group NGC 6482: Evidence for Weak Adiabatic Contraction

    NASA Astrophysics Data System (ADS)

    Buote, David A.

    2017-01-01

    Although fossil galaxy systems are thought to be very old, and thus should possess above-average halo concentrations, typically fossils have unexceptional concentrations of their masses. We revisit the massive isolated elliptical galaxy/fossil group NGC 6482 for which previous X-ray studies of a modest Chandra observation obtained a very uncertain, but also possibly very high, halo concentration. We present new measurements of the hot gas surface brightness, temperature, and iron abundance using the modest Chandra observation and a previously unpublished Suzaku observation, the latter of which allows the measurements of the gas properties to be extended out to ∼ {r}2500. By constructing hydrostatic equilibrium models of the gas with separate components for the gas, the stellar mass of the large central galaxy (BCG), and the dark matter (DM), we measure {c}200=32.2+/- 7.1 and {M}200=(4.5+/- 0.6)× {10}12 {M}ȯ using a Navarro-Frenk-White (NFW) DM profile. For a halo of this mass, the measured concentration c200 exceeds the mean value (7.1) expected for relaxed ΛCDM halos by 3.5σ in terms of the observational error, and by 6σ considering the intrinsic scatter in the ΛCDM c–M relation, which situates NGC 6482 as the most extreme outlier known for a fossil system. We explored several variants of adiabatic contraction (AC) models and, while the AC models provide fits of the same quality as the uncontracted models, they do have the following advantages: (1) lower c200 that is less of an outlier in the ΛCDM c–M relation, and (2) baryon fractions ({f}{{b},200}) that agree better with the mean cosmic value. While the standard AC prescriptions yield a BCG stellar mass that is uncomfortably low compared to results from stellar population synthesis (SPS) models, a weaker AC variant that artificially shuts off cooling and star formation at z = 2 yields the same stellar mass as the uncontracted models. These are probably the reasons why our X-ray analysis prefers this

  2. High-power, high-efficiency FELs

    SciTech Connect

    Sessler, A.M.

    1989-04-01

    High power, high efficiency FELs require tapering, as the particles loose energy, so as to maintain resonance between the electromagnetic wave and the particles. They also require focusing of the particles (usually done with curved pole faces) and focusing of the electromagnetic wave (i.e. optical guiding). In addition, one must avoid transverse beam instabilities (primarily resistive wall) and longitudinal instabilities (i.e sidebands). 18 refs., 7 figs., 3 tabs.

  3. High Efficiency Room Air Conditioner

    SciTech Connect

    Bansal, Pradeep

    2015-01-01

    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, 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%.

  4. Fossil Fuel Combustion Fingerprint in High-Resolution Urban Water Vapor Isotope Measurements

    NASA Astrophysics Data System (ADS)

    Gorski, G.; Good, S. P.; Bowen, G. J.

    2014-12-01

    Increasing energy consumption and rapid urbanization have many important and poorly understood consequences for the hydrologic cycle in urban and suburban areas. Wide use of fossil fuels for transportation and heating releases isotopically distinctive water vapor that contributes to the overall water vapor budget in varying, usually unknown, concentrations. The use of long term, high resolution isotopic measurements can help determine different sources and proportions of water vapor at various time scales. We present two months of high-resolution water vapor isotope measurements coupled with CO2 concentrations and co-located meteorological observations from December 2013 - January 2014 in Salt Lake City, UT. Periods of atmospheric stagnation (cold-air inversions) show a buildup of CO2 from baseline values of 420 ppm to as high as 600 ppm and an associated decrease in water vapor deuterium-excess values from a baseline of approx. 10‰ to values as low as -10‰ (where d = δ2H - 8*δ18O, in per mil units). We suggest that the strong relationship between CO2and d during inversion periods is driven by the build-up of fossil fuel combustion-derived water vapor with very low d values (≤ -150‰). Based on our measurements of its isotopic composition, combustion-derived water vapor could contribute as much as 15% to the total water vapor budget during inversion periods. We present evidence of this effect at both the multi-day scale and the diurnal scale, where periods of increased automobile use and home heating can be identified. This study provides the first isotopic evidence that accumulation of water of combustion can be identified in boundary layer water vapor, suggests that an appreciable fraction of boundary layer vapor can be derived from combustion under certain atmospheric conditions, and indicates that the distinctive d values of combustion-derived vapor may be a useful tracer for this component of the atmospheric water budget in other urban regions.

  5. High Efficiency Germanium Immersion Gratings

    SciTech Connect

    Kuzmenko, P J; Davis, P J; Little, S L; Little, L M; Bixler, J V

    2006-05-01

    We have fabricated several germanium immersion gratings by single crystal, single point diamond flycutting on an ultra-precision lathe. Use of a dead sharp tool produces groove corners less than 0.1 micron in radius and consequently high diffraction efficiency. We measured first order efficiencies in immersion of over 80% at 10.6 micron wavelength. Wavefront error was low averaging 0.06 wave rms (at 633 nm) across the full aperture. The grating spectral response was free of ghosts down to our detection limit of 1 part in 10{sup 4}. Scatter should be low based upon the surface roughness. Measurement of the spectral line profile of a CO{sub 2} laser sets an upper bound on total integrated scatter of 0.5%.

  6. High Efficiency IMM Solar Cells

    NASA Astrophysics Data System (ADS)

    Sharps, P.; Cho, B.; Chumney, D.; Cornfeild, A.; Guzie, B.; Hazlett, D.; Lin, Y.; Mackos, C.; Patel, P.; Stan, M.; Steinfeldt, J.; Tourino, C.

    2014-08-01

    We review the status of currently available commercial multi-junction cells, review options for next generation high efficiency cell architectures, and present the latest developments on the inverted metamorphic multi- junction (IMM) solar cell. Over 20,000 IMM cells have been prototyped to date, and efficiencies of up to 37% have been measured. We present the most recent performance data, including the response to particle radiation. The IMM cell can be used in a number of rigid or flexible configurations, and considerable effort is currently focused on cell packaging and panel integration. We discuss several design options, including a "drop in" replacement for the current 29.5% ZTJ cell technology. We will also address the reliability and cost of the IMM cell.

  7. "Fossil" Forecasting.

    ERIC Educational Resources Information Center

    Brody, Michael J.; deOnis, Ann

    2001-01-01

    Presents a density study in which students calculate the density of limestone substrate to determine if the specimen contains any fossils. Explains how to make fossils and addresses national standards. (YDS)

  8. A simple, high efficiency, high resolution spectropolarimeter

    NASA Astrophysics Data System (ADS)

    Barden, Samuel C.

    2012-09-01

    A simple concept is described that uses volume phase holographic gratings as polarizing dispersers for a high efficiency, high resolution spectropolarimeter. Although the idea has previously been mentioned in the literature as possible, such a concept has not been explored in detail. Performance analysis is presented for a VPHG spectropolarimeter concept that could be utilized for both solar and night-time astronomy. Instrumental peak efficiency can approach 100% with spectral dispersions permitting R~200,000 spectral resolution with diffraction limited telescopes. The instrument has 3-channels: two dispersed image planes with orthogonal polarization and an undispersed image plane. The concept has a range of versatility where it could be configured (with appropriate half-wave plates) for slit-fed spectroscopy or without slits for snapshot/hyperspectral/tomographic spectroscopic imaging. Multiplex gratings could also be used for the simultaneous recording of two separate spectral bands or multiple instruments could be daisy chained with beam splitters for further spectral coverage.

  9. Krakow clean fossil fuels and energy efficiency program. Phase 1 report

    SciTech Connect

    Butcher, T.; Pierce, B.

    1995-06-01

    Krakow is one of the largest and oldest cities in Poland. It is situated in the south of the country on the banks of the Vistula River. From the 11th until the 17th centuries, it was the capital of Poland. Today, Krakow is a city of 750,000 residents, one of the largest centers of higher education, an important industrial center, and is of particular importance because of the number and kinds of historic buildings and sites. For this reason, Krakow was included by the UNESCO in the list of the world`s cultural heritages. For about three decades, significant air pollution has been one of Krakow`s most serious problems. Because the city is situated in the Vistula River valley, it is poorly ventilated and experiences a high concentration of air pollutants. The quality of air in Krakow is affected mainly by industry (Sendzimir Steelworks, energy industry, chemical plants), influx from the Silesian industrial region (power plants, metallurgy), transboundary pollution (Ostrava - Czech Republic), and local sources of low pollution, i.e. more than 1,000 boiler houses using solid fuels and more than 100,000 coal-fired home stoves. These local sources, with low stacks and almost no pollution-control equipment, are responsible for about 35-40% of the air pollution. This report presents phase I results of a program to reduce pollution in krakow. Phase I was to gather information on emissions and costs, and to verify assumptions on existing heating methods and alternatives.

  10. Fossil Explorers

    ERIC Educational Resources Information Center

    Moran, Sean; McLaughlin, Cheryl; MacFadden, Bruce; Jacobbe, Elizabeth; Poole, Michael

    2015-01-01

    Many young learners are fascinated with fossils, particularly charismatic forms such as dinosaurs and giant sharks. Fossils provide tangible, objective evidence of life that lived millions of years ago. They also provide a timescale of evolution not typically appreciated by young learners. Fossils and the science of paleontology can, therefore,…

  11. Marquee Fossils

    ERIC Educational Resources Information Center

    Clary, Renee; Wandersee, James

    2008-01-01

    Professors of an online graduate-level paleontology class developed the concept of marquee fossils--fossils that have one or more unique characteristics that capture the attention and direct observation of students. In the classroom, Marquee fossils integrate the geology, biology, and environmental science involved in the study of fossilized…

  12. High efficiency motor rewind study

    NASA Astrophysics Data System (ADS)

    Wallace, A. K.; Spee, R.

    1991-02-01

    The objective of performing this work was to evaluate a new technology used for rewinding electric motors. Motor performance evaluation was conducted at the motor test facility at Oregon State University. The test program consisted of comparing new high efficiency motor technology and standard rewind technology with the Unity-Plus system. The Unity-Plus configuration exhibited reduced efficiency over the complete load range compared to the other motors. Appropriately sized capacitors connected to the terminals of the conventional induction motor produced the same power factor improvement as the Unity-Plus system. Torque production and torque pulsation were very similar for all systems. The Unity-Plus configuration drew lower starting currents but the duration of the starting transient was increased. Motor temperature rise was about the same for all systems. Noise levels were about the same in all systems. Although determination of time to failure was not undertaken, the expected lifetime of the Unit-Plus system is probably less due to higher capacitor stress and higher insulation stress. The investigation concludes that a conventional induction motor with terminal capacitors is the most acceptable way of obtaining good efficiency and power factor and the Unity-Plus system cannot be recommended on the basis of any of the evaluation criteria used in this study.

  13. Fossil fuels -- future fuels

    SciTech Connect

    1998-03-01

    Fossil fuels -- coal, oil, and natural gas -- built America`s historic economic strength. Today, coal supplies more than 55% of the electricity, oil more than 97% of the transportation needs, and natural gas 24% of the primary energy used in the US. Even taking into account increased use of renewable fuels and vastly improved powerplant efficiencies, 90% of national energy needs will still be met by fossil fuels in 2020. If advanced technologies that boost efficiency and environmental performance can be successfully developed and deployed, the US can continue to depend upon its rich resources of fossil fuels.

  14. 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.

  15. Sun, Ocean, Nuclear Bombs, and Fossil Fuels: Radiocarbon Variations and Implications for High-Resolution Dating

    NASA Astrophysics Data System (ADS)

    Dutta, Koushik

    2016-06-01

    Radiocarbon, or 14C, is a radiometric dating method ideally suited for providing a chronological framework in archaeology and geosciences for timescales spanning the last 50,000 years. 14C is easily detectable in most common natural organic materials and has a half-life (5,730±40 years) relevant to these timescales. 14C produced from large-scale detonations of nuclear bombs between the 1950s and the early 1960s can be used for dating modern organic materials formed after the 1950s. Often these studies demand high-resolution chronology to resolve ages within a few decades to less than a few years. Despite developments in modern, high-precision 14C analytical methods, the applicability of 14C in high-resolution chronology is limited by short-term variations in atmospheric 14C in the past. This article reviews the roles of the principal natural drivers (e.g., solar magnetic activity and ocean circulation) and the anthropogenic perturbations (e.g., fossil fuel CO2 and 14C from nuclear and thermonuclear bombs) that are responsible for short-term 14C variations in the environment. Methods and challenges of high-resolution 14C dating are discussed.

  16. High efficiency shale oil recovery

    SciTech Connect

    Adams, C.D.

    1992-07-18

    The overall project objective is to demonstrate the high efficiency of the Adams Counter-Current shale oil recovery process. The efficiency will first be demonstrated at bench-scale, in the current phase, after which the demonstration will be extended to the operation of a small pilot plant. Thus the immediate project objective is to obtain data on oil shale retorting operations in a small batch rotary kiln that will be representative of operations in the proposed continuous process pilot plant. Although an oil shale batch sample is sealed in the batch kiln from the start until the end of the run, the process conditions for the batch are the same as the conditions that an element of oil shale would encounter in a larger continuous process kiln. For example, similar conditions of heatup rate, oxidation of the residue and cool-down prevail for the element in both systems. This batch kiln is a unit constructed in a 1987 Phase I SBIR tar sand retorting project. The kiln worked fairly well in that project; however, the need for certain modifications was observed. These modifications are now underway to simplify the operation and make the data and analysis more exact. The second quarter agenda consisted of (a) kiln modifications; (b) sample preparation; and (c) Heat Transfer calibration runs (part of proposal task number 3 -- to be completed by the end of month 7).

  17. Parameter Estimation of Fossil Oysters from High Resolution 3D Point Cloud and Image Data

    NASA Astrophysics Data System (ADS)

    Djuricic, Ana; Harzhauser, Mathias; Dorninger, Peter; Nothegger, Clemens; Mandic, Oleg; Székely, Balázs; Molnár, Gábor; Pfeifer, Norbert

    2014-05-01

    A unique fossil oyster reef was excavated at Stetten in Lower Austria, which is also the highlight of the geo-edutainment park 'Fossilienwelt Weinviertel'. It provides the rare opportunity to study the Early Miocene flora and fauna of the Central Paratethys Sea. The site presents the world's largest fossil oyster biostrome formed about 16.5 million years ago in a tropical estuary of the Korneuburg Basin. About 15,000 up to 80-cm-long shells of Crassostrea gryphoides cover a 400 m2 large area. Our project 'Smart-Geology for the World's largest fossil oyster reef' combines methods of photogrammetry, geology and paleontology to document, evaluate and quantify the shell bed. This interdisciplinary approach will be applied to test hypotheses on the genesis of the taphocenosis (e.g.: tsunami versus major storm) and to reconstruct pre- and post-event processes. Hence, we are focusing on using visualization technologies from photogrammetry in geology and paleontology in order to develop new methods for automatic and objective evaluation of 3D point clouds. These will be studied on the basis of a very dense surface reconstruction of the oyster reef. 'Smart Geology', as extension of the classic discipline, exploits massive data, automatic interpretation, and visualization. Photogrammetry provides the tools for surface acquisition and objective, automated interpretation. We also want to stress the economic aspect of using automatic shape detection in paleontology, which saves manpower and increases efficiency during the monitoring and evaluation process. Currently, there are many well known algorithms for 3D shape detection of certain objects. We are using dense 3D laser scanning data from an instrument utilizing the phase shift measuring principle, which provides accurate geometrical basis < 3 mm. However, the situation is difficult in this multiple object scenario where more than 15,000 complete or fragmentary parts of an object with random orientation are found. The goal

  18. High efficiency laser spectrum conditioner

    DOEpatents

    Greiner, Norman R.

    1980-01-01

    A high efficiency laser spectrum conditioner for generating a collinear parallel output beam containing a predetermined set of frequencies from a multifrequency laser. A diffraction grating and spherical mirror are used in combination, to disperse the various frequencies of the input laser beam and direct these frequencies along various parallel lines spatially separated from one another to an apertured mask. Selection of the desired frequencies is accomplished by placement of apertures at locations on the mask where the desired frequencies intersect the mask. A recollimated parallel output beam with the desired set of frequencies is subsequently generated utilizing a mirror and grating matched and geometrically aligned in the same manner as the input grating and mirror.

  19. High efficiency ozone generation system

    SciTech Connect

    Karlson, E.L.

    1990-01-09

    This final report entails research prepared to verify the workings and the efficiency of producing ozone with the ELK'' Ozone Generator, which operates at an elevated gas pressure of up to 20 MPA (3000 psi) and is an improvement of the corona discharge ozone generator. The increased pressure produces an increase in the density of oxygen gas fed into the generator. This, in turn, leads to an increased yield of ozone in the ozone oxygen gas mixture leaving the generator. The design of this new ozone generator incorporates a novel positioning of the dielectric to preserve its mechanical integrity at high operating pressures and also incorporates a novel heat removal technique. A large number of ozone production runs have been made at different pressures. Large populations of data such as, temperature points throughout the generator, gas flow, cooling water flow parameters, operating gas pressure, ozone concentration, and data on the dielectric cooling, have been compiled and fed into our computer. This new data indicates not only that high pressures used in a controlled fashion will produce more ozone per watt hour but also indicates what problems exist when pressures are increased, such as the generation of high temperatures not only in the area of ozone generation but within the dielectric. The data also shows the necessary residence time for maximum ozone production at a particular pressure, voltage, temperature and electrode spacing. 14 refs., 22 figs.

  20. HIGH EFFICIENCY GENERATION OF HYDROGEN FUELS USING NUCLEAR POWER

    SciTech Connect

    BROWN,LC; BESENBRUCH,GE; LENTSCH,RD; SCHULTZ,KR; FUNK,JF; PICKARD,PS; MARSHALL,AC; SHOWALTER,SK

    2003-06-01

    OAK B202 HIGH EFFICIENCY GENERATION OF HYDROGEN FUELS USING NUCLEAR POWER. Combustion of fossil fuels, used to power transportation, generate electricity, heat homes and fuel industry provides 86% of the world's energy. Drawbacks to fossil fuel utilization include limited supply, pollution, and carbon dioxide emissions. Carbon dioxide emissions, thought to be responsible for global warming, are now the subject of international treaties. Together, these drawbacks argue for the replacement of fossil fuels with a less-polluting potentially renewable primary energy such as nuclear energy. Conventional nuclear plants readily generate electric power but fossil fuels are firmly entrenched in the transportation sector. Hydrogen is an environmentally attractive transportation fuel that has the potential to displace fossil fuels. Hydrogen will be particularly advantageous when coupled with fuel cells. Fuel cells have higher efficiency than conventional battery/internal combustion engine combinations and do not produce nitrogen oxides during low-temperature operation. Contemporary hydrogen production is primarily based on fossil fuels and most specifically on natural gas. When hydrogen is produced using energy derived from fossil fuels, there is little or no environmental advantage. There is currently no large scale, cost-effective, environmentally attractive hydrogen production process available for commercialization, nor has such a process been identified. The objective of this work is to find an economically feasible process for the production of hydrogen, by nuclear means, using an advanced high-temperature nuclear reactor as the primary energy source. Hydrogen production by thermochemical water-splitting (Appendix A), a chemical process that accomplishes the decomposition of water into hydrogen and oxygen using only heat or, in the case of a hybrid thermochemical process, by a combination of heat and electrolysis, could meet these goals. Hydrogen produced from fossil

  1. High efficiency shale oil recovery

    SciTech Connect

    Adams, D.C.

    1992-01-01

    The overall project objective is to demonstrate the high efficiency of the Adams Counter-Current shale oil recovery process. The efficiency will first be demonstrated at bench-scale, in the current phase, after which the demonstration will be extended to the operation of a small pilot plant. Thus the immediate project objective is to obtain data on oil shale retorting operations in a small batch rotary kiln that will be representative of operations in the proposed continuous process pilot plant. Although a batch oil shale sample will be sealed in the batch kiln from the start until the end of the run, the process conditions for the batch will be the same as the conditions that an element of oil shale would encounter in a large continuous process kiln. For example, similar conditions of heat-up rate (20 deg F/min during the pyrolysis), oxidation of the residue and cool-down will prevail for the element in both systems. This batch kiln is a unit constructed in a 1987 Phase I SBIR tar sand retorting project. The kiln worked fairly well in that project; however, the need for certain modifications was observed. These modifications are now underway to simplify the operation and make the data and analysis more exact. The agenda for the first three months of the project consisted of the first of nine tasks and was specified as the following four items: 1. Sample acquisition and equipment alteration: Obtain seven oil shale samples, of varying grade each 10 lb or more, and samples of quartz sand. Order equipment for kiln modification. 3. Set up and modify kiln for operation, including electric heaters on the ends of the kiln. 4. Connect data logger and make other repairs and changes in rotary batch kiln.

  2. High efficiency shale oil recovery

    SciTech Connect

    Adams, D.C.

    1993-04-22

    The overall project objective is to demonstrate the high efficiency of the Adams Counter-Current shale oil recovery process. The efficiency will first be demonstrated on a small scale, in the current phase, after which the demonstration will be extended to the operation of a small pilot plant. Thus the immediate project objective is to obtain data on oil shale retorting operations in a small batch rotary kiln that will be representative of operations in the proposed continuous process pilot plant. Although an oil shale batch sample is sealed in the batch kiln from the start until the end of the run, the process conditions for the batch are the same as the conditions that an element of oil shale would encounter in a continuous process kiln. Similar chemical and physical conditions (heating, mixing, pyrolysis, oxidation) exist in both systems.The two most important data objectives in this phase of the project are to demonstrate (1) that the heat recovery projected for this project is reasonable and (2) that an oil shale kiln will run well and not plug up due to sticking and agglomeration. The following was completed this quarter. (1) Twelve pyrolysis runs were made on five different oil shales. All of the runs exhibited a complete absence of any plugging, tendency. Heat transfer for Green River oil shale in the rotary kiln was 84.6 Btu/hr/ft[sup 2]/[degrees]F, and this will provide for ample heat exchange in the Adams kiln. (2) One retorted residue sample was oxidized at 1000[degrees]F. Preliminary indications are that the ash of this run appears to have been completely oxidized. (3) Further minor equipment repairs and improvements were required during the course of the several runs.

  3. Fossilized high pressure from the Earth's deep interior: The coesite-in-diamond barometer

    PubMed Central

    Sobolev, Nikolai V.; Fursenko, Boris A.; Goryainov, Sergei V.; Shu, Jinfu; Hemley, Russell J.; Mao, Ho-kwang; Boyd, Francis R.

    2000-01-01

    Mineral inclusions in diamonds provide an important source of information about the composition of the continental lithosphere at depths exceeding 120–150 km, i.e., within the diamond stability field. Fossilized high pressures in coesite inclusions from a Venezuela diamond have been identified and measured by using laser Raman and synchrotron x-ray microanalytical techniques. Micro-Raman measurements on an intact inclusion of remnant vibrational band shifts give a high confining pressure of 3.62 (±0.18) GPa. Synchrotron single-crystal diffraction measurements of the volume compression are in accord with the Raman results and also revealed direct structural information on the state of the inclusion. In contrast to olivine and garnet inclusions, the thermoelasticity of coesite favors accurate identification of pressure preservation. Owing to the unique combination of physical properties of coesite and diamond, this “coesite-in-diamond” geobarometer is virtually independent of temperature, allowing an estimation of the initial pressure of Venezuela diamond formation of 5.5 (±0.5) GPa. PMID:11035808

  4. High Efficiency Solar Power via Separated Photo and Voltaic Pathways

    SciTech Connect

    Michael J. Naughton

    2009-02-17

    This project demonstrates a novel nanostructured solar cell architecture capable of achieving high efficiency levels that is relatively simple and inexpensive to manufacture. The high efficiency will be achieved by the novel structure that separates the path of the photons from the path of the generated charge carriers. In this way, the photon path can be long for maximum light absorption, while the path for carriers can be short for maximum electronic energy harvesting. The combination of maximum light absorption coupled with maximum carrier harvesting is the basis for the expected high efficiency. The project will develop high efficiency solar cell prototypes utilizing this unique nanostructured architecture. The project addresses the fundamental limitation inherent in all current solar cell designs, and which opens a pathway to development for high efficiency solar cells at low cost. Realizing this goal will result in a levelized cost of electricity in the range of 10¢/kWh, which would achieve the long-sought goal of making photovoltaic electricity cost competitive with fossil-fuel generated electricity without any governmental subsidies. This breakthrough would spur the already rapid growth in the photovoltaic industry to an explosive pace, with significant, widespread benefit to the national economy and the nation’s energy security. The initial target of the program is to develop single-junction solar cells using ultrathin amorphous silicon with the performance approaching that of single crystal silicon cells.

  5. High Efficiency Cascade Solar Cells

    SciTech Connect

    Shuguang Deng, Seamus Curran, Igor Vasiliev

    2010-09-28

    This report summarizes the main work performed by New Mexico State University and University of Houston on a DOE sponsored project High Efficiency Cascade Solar Cells. The main tasks of this project include materials synthesis, characterization, theoretical calculations, organic solar cell device fabrication and test. The objective of this project is to develop organic nano-electronic-based photovoltaics. Carbon nanotubes and organic conjugated polymers were used to synthesize nanocomposites as the new active semiconductor materials that were used for fabricating two device architectures: thin film coating and cascade solar cell fiber. Chemical vapor deposition technique was employed to synthesized a variety of carbon nanotubes (single-walled CNT, doubled-walled CNT, multi-walled CNT, N-doped SWCNT, DWCNT and MWCNT, and B-doped SWCNT, DWCNT and MWCNT) and a few novel carbon structures (CNT-based nanolance, nanocross and supported graphene film) that have potential applications in organic solar cells. Purification procedures were developed for removing amorphous carbons from carbon nanotubes, and a controlled oxidation method was established for partial truncation of fullerene molecules. Carbon nanotubes (DWCNT and DWCNT) were functionalized with fullerenes and dyes covalently and used to form nanocomposites with conjugated polymers. Biologically synthesized Tellurium nanotubes were used to form composite with the conjugated polymers as well, which generated the highest reported optical limiting values from composites. Several materials characterization technique including SEM/TEM, Raman, AFM, UV-vis, adsorption and EDS were employed to characterize the physical and chemical properties of the carbon nanotubes, the functionalized carbon nanotubes and the nanocomposites synthesized in this project. These techniques allowed us to have a spectroscopic and morphological control of the composite formation and to understand the materials assembled. A parallel 136-CPU

  6. Restoring Fossil Creek

    ERIC Educational Resources Information Center

    Flaccus, Kathleen; Vlieg, Julie; Marks, Jane C.; LeRoy, Carri J.

    2004-01-01

    Fossil Creek had been dammed for the past 90 years, and plans were underway to restore the stream. The creek runs through Central Arizona and flows from the high plateaus to the desert, cutting through the same formations that form the Grand Canyon. This article discusses the Fossil Creek monitoring project. In this project, students and teachers…

  7. High-resolution leaf-fossil record spanning the Cretaceous/Tertiary boundary

    USGS Publications Warehouse

    Johnson, K.R.; Nichols, D.J.; Attrep, M.; Orth, C.J.

    1989-01-01

    THEORIES that explain the extinctions characterizing the Cretaceous/Tertiary (K/T) boundary1-3 need to be tested by analyses of thoroughly sampled biotas. Palynological studies are the primary means for stratigraphic placement of the terrestrial boundary and for estimates of plant extinction4-12, but have not been combined with quantitative analyses of fossil leaves (megaflora). Megafloral studies complement palynology by representing local floras with assemblages capable of high taxonomic resolution13, but have previously lacked the sample size and stratigraphic spacing needed to resolve latest Cretaceous floral history5,14-18. We have now combined megafloral data from a 100-m-thick composite K/T boundary section in North Dakota with detailed palynological analysis. Here the boundary is marked by a 30% palynofloral extinction coincident with iridium and shocked-mineral anomalies and lies ???2 m above the highest dinosaur remains. The megaflora undergoes a 79% turnover across the boundary, and smaller changes 17- and 25-m below it. This pattern is consistent with latest Cretaceous climatic warming preceding a bolide impact. ?? 1989 Nature Publishing Group.

  8. Towards highly efficient water photoelectrolysis

    NASA Astrophysics Data System (ADS)

    Elavambedu Prakasam, Haripriya

    ethylene glycol resulted in remarkable growth characteristics of titania nanotube arrays, hexagonal closed packed up to 1 mm in length, with tube aspect ratios of approximately 10,000. For the first time, complete anodization of the starting titanium foil has been demonstrated resulting in back to back nanotube array membranes ranging from 360 mum--1 mm in length. The nanotubes exhibited growth rates of up to 15 mum/hr. A detailed study on the factors affecting the growth rate and nanotube dimensions is presented. It is suggested that faster high field ionic conduction through a thinner barrier layer is responsible for the higher growth rates observed in electrolytes containing ethylene glycol. Methods to fabricate free standing, titania nanotube array membranes ranging in thickness from 50 microm--1000 mum has also been an outcome of this dissertation. In an effort to combine the charge transport properties of titania with the light absorption properties of iron (III) oxide, films comprised of vertically oriented Ti-Fe-O nanotube arrays on FTO coated glass substrates have been successfully synthesized in ethylene glycol electrolytes. Depending upon the Fe content the bandgap of the resulting films varied from about 3.26 to 2.17 eV. The Ti-Fe oxide nanotube array films demonstrated a photocurrent of 2 mA/cm2 under global AM 1.5 illumination with a 1.2% (two-electrode) photoconversion efficiency, demonstrating a sustained, time-energy normalized hydrogen evolution rate by water splitting of 7.1 mL/W·hr in a 1 M KOH solution with a platinum counter electrode under an applied bias of 0.7 V. The Ti-Fe-O material architecture demonstrates properties useful for hydrogen generation by water photoelectrolysis and, more importantly, this dissertation demonstrates that the general nanotube-array synthesis technique can be extended to other ternary oxide compositions of interest for water photoelectrolysis.

  9. Transport realization of high resolution fossil fuel CO2 emissions in an urban domain

    NASA Astrophysics Data System (ADS)

    Zhou, Y.; Gurney, K. R.

    2010-12-01

    CO2 emissions from fossil fuel combustion are the largest net annual flux of carbon in the earth atmosphere system and energy consumption in urban environments is a major contributor to total fossil fuel CO2 emissions. Understanding how the emissions are transported in space and time, especially in urban environments and resolving contributions from individual sources of fossil-fuel CO2 emissions are an essential component of a complete reliable monitoring, reporting, and verification (MRV) system that are emerging at local, national, and international levels. As grid models are not designed to resolve concentrations on local scales, we tested the transport realization of fossil fuel CO2 emissions using the Hybrid Single Particle Lagrangian Integrated Trajectory Model (HYSPLIT) model, a commonly used transport algorithm for small domain air quality studies, in the greater Indianapolis region, USA. A typical 24-hour point, mobile, and area sources fossil fuel CO2 emissions in four seasons (spring, summer, autumn and winter) were processed from hourly emissions data and prepared at 500-meter spatial resolution for the model inputs together with other parameters. The simulation result provides a complete 4-dimensional concentration matrix transported from all sources for the urban domain which can be analyzed in order to isolate individual sources or test sampling strategies for verification at selected time periods. In addition, the urban 4-dimensional concentration matrix can be visualized in a virtual environment, which provides a powerful education and outreach platform for researchers, students, and public.

  10. Fossil Fuels.

    ERIC Educational Resources Information Center

    Crank, Ron

    This instructional unit is one of 10 developed by students on various energy-related areas that deals specifically with fossil fuels. Some topics covered are historic facts, development of fuels, history of oil production, current and future trends of the oil industry, refining fossil fuels, and environmental problems. Material in each unit may…

  11. Ediacara Fossils

    ERIC Educational Resources Information Center

    Science Teacher, 2005

    2005-01-01

    Now, a research team from Virginia Tech and Nanjing Institute of Geology and Paleontology has discovered uniquely well-preserved fossil forms from 550-million-year-old rocks of the Ediacaran Period. The research appears in the Proceedings of the National Academy of Sciences. The discovery of these unusually preserved fossils reveals unprecedented…

  12. 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.

  13. Generating clean energy at high efficiency and low cost

    NASA Astrophysics Data System (ADS)

    Chang, Yan P.

    1991-06-01

    This paper is related to thermal energy conversion with particular attention to the utilization of thermal energy from environmental fluids according to concepts in equilibrium and nonequilibrium thermodynamics. The first step is to prove that a single fluid heat source can produce useful work, so that thermal energy of environmental fluids is not at 'dead state.' An ocean thermal energy conversion (OTEC) system can be easily constructed at higher efficiency and lower cost than existing OTEC systems. An atmosphere thermal energy conversion (ATEC) system of high efficiency and low cost is more sophisticated. It requires open or closed counter-clockwise cycles comprising isothermal compressible flow with or without heat transfer. Combination of one of such ATEC System and a cyclic system, and supplementation of fossil or nuclear fission fuel as an additional heat source are discussed for particular applications.

  14. High efficiency turbine blade coatings

    SciTech Connect

    Youchison, Dennis L.; Gallis, Michail A.

    2014-06-01

    The development of advanced thermal barrier coatings (TBCs) of yttria stabilized zirconia (YSZ) that exhibit lower thermal conductivity through better control of electron beam - physical vapor deposition (EB-PVD) processing is of prime interest to both the aerospace and power industries. This report summarizes the work performed under a two-year Lab-Directed Research and Development (LDRD) project (38664) to produce lower thermal conductivity, graded-layer thermal barrier coatings for turbine blades in an effort to increase the efficiency of high temperature gas turbines. This project was sponsored by the Nuclear Fuel Cycle Investment Area. Therefore, particular importance was given to the processing of the large blades required for industrial gas turbines proposed for use in the Brayton cycle of nuclear plants powered by high temperature gas-cooled reactors (HTGRs). During this modest (~1 full-time equivalent (FTE)) project, the processing technology was developed to create graded TBCs by coupling ion beam-assisted deposition (IBAD) with substrate pivoting in the alumina-YSZ system. The Electron Beam - 1200 kW (EB-1200) PVD system was used to deposit a variety of TBC coatings with micron layered microstructures and reduced thermal conductivity below 1.5 W/m.K. The use of IBAD produced fully stoichiometric coatings at a reduced substrate temperature of 600°C and a reduced oxygen background pressure of 0.1 Pa. IBAD was also used to successfully demonstrate the transitioning of amorphous PVD-deposited alumina to the -phase alumina required as an oxygen diffusion barrier and for good adhesion to the substrate Ni2Al3 bondcoat. This process replaces the time consuming thermally grown oxide formation required before the YSZ deposition. In addition to the process technology, Direct Simulation Monte Carlo plume modeling and spectroscopic characterization of the PVD plumes were performed. The project consisted of five tasks. These included the

  15. High-precision 40Ar/39Ar ages for the Jehol fossil-bearing formations in SE China

    NASA Astrophysics Data System (ADS)

    Chang, S.; Zhang, H.; Hemming, S. R.; Fang, Y.; Mesko, G. T.

    2009-12-01

    The Jehol Biota, defined as the characteristic Eosestheria-Ephemeropsis-Lycoptera assemblage, is known to be widely distributed in East Asia. The fossils of the Jehol Biota are magnificent, exquisitely preserved and extraordinarily diverse. Since the 1990s, abundant and varied fossils, including plants, insects, salamanders, dinosaurs, pterosaurs, choristoderes, birds, mammals and freshwater invertebrates, have been discovered from the Dabeigou, Yixian and Jiufotang Formations in Inner Mongolia, and Liaoning and Hebei Provinces of NE China. Each of these Jehol fossil-bearing formations has preserved a distinct assemblage of invertebrate and vertebrate fossils. Based on major invertebrates groups, the Jehol Biota has been divided into three developing stages and a hypothesis about its distribution and spread has been proposed. There is a clear progression towards greater diversity through the three phases and it corresponds to a progressive paleogeographic expansion through time. In addition to their extensive distribution in Inner Mongolia and NE China, other strata that contain Jehol related fossils have been identified in the central and most provinces of eastern China, the Korean Peninsula, Mongolia and Siberia. However, the detailed correlation between the classic Jehol outcrops and the less-studied localities requires further work, including high-resolution ages. We are analyzing sixteen volcanic samples from Zhejiang and Anhui Provinces to establish a high-precision chronostratigraphy for the less-studied localities across SE China and adjacent regions. Our work will provide important data to test the timing and the duration of three phases of the Jehol radiation. Furthermore, the age results will allow us to understand the temporal relationship among the Jehol localities and test if the later phases of the Jehol radiation had broader geographic distributions, as inferred from existing collections.

  16. Using Fossil Shark Teeth to Illustrate Evolution and Introduce Basic Geologic Concepts in a High School Biology Classroom

    NASA Astrophysics Data System (ADS)

    Agnew, J. G.; Nunn, J. A.

    2007-12-01

    Shell Foundation sponsors a program at Louisiana State University called Shell Undergraduate Recruitment and Geoscience Education (SURGE). The purpose of SURGE is to help local high school science teachers incorporate geology into their classrooms by providing resources and training. As part of this program, a workshop for high school biology teachers was held at Louisiana State University in Baton Rouge on June 3-5, 2007. We had the teachers do a series of activities on fossil shark teeth to illustrate evolution and introduce basic earth science concepts such as geologic time, superposition, and faunal succession and provided the teachers with lesson plans and materials. As an example, one of our exercises explores the evolution of the megatoothed shark lineage leading to Carcharocles megalodon, the largest predatory shark in history with teeth up to 17 cm long. Megatoothed shark teeth make excellent evolutionary subjects because they have a good fossil record and show continuous transitions in morphology from the Eocene to Pliocene. Our activity follows the learning cycle model. We take advantage of the curiosity of sharks shared by most people, and allow students to explore the variations among different shark teeth and explain the causes of those variations. The objectives of this exercise are to have the students: 1) sort fossil shark teeth into biologically reasonable species; 2) form hypotheses about evolutionary relationships among fossil shark teeth; and 3) describe and interpret evolutionary trends in the fossil Megatoothed lineage. To do the activity, students are divided into groups of 2-3 and given a shuffled set of 72 shark tooth cards with different images of megatoothed shark teeth. They are instructed to group the shark tooth cards into separate species of sharks. After sorting the cards, students are asked to consider the evolutionary relationships among their species and arrange their species chronologically according to the species first

  17. High Energy Efficiency Air Conditioning

    SciTech Connect

    Edward McCullough; Patrick Dhooge; Jonathan Nimitz

    2003-12-31

    This project determined the performance of a new high efficiency refrigerant, Ikon B, in a residential air conditioner designed to use R-22. The refrigerant R-22, used in residential and small commercial air conditioners, is being phased out of production in developed countries beginning this year because of concerns regarding its ozone depletion potential. Although a replacement refrigerant, R-410A, is available, it operates at much higher pressure than R-22 and requires new equipment. R-22 air conditioners will continue to be in use for many years to come. Air conditioning is a large part of expensive summer peak power use in many parts of the U.S. Previous testing and computer simulations of Ikon B indicated that it would have 20 - 25% higher coefficient of performance (COP, the amount of cooling obtained per energy used) than R-22 in an air-cooled air conditioner. In this project, a typical new R-22 residential air conditioner was obtained, installed in a large environmental chamber, instrumented, and run both with its original charge of R-22 and then with Ikon B. In the environmental chamber, controlled temperature and humidity could be maintained to obtain repeatable and comparable energy use results. Tests with Ikon B included runs with and without a power controller, and an extended run for several months with subsequent analyses to check compatibility of Ikon B with the air conditioner materials and lubricant. Baseline energy use of the air conditioner with its original R-22 charge was measured at 90 deg F and 100 deg F. After changeover to Ikon B and a larger expansion orifice, energy use was measured at 90 deg F and 100 deg F. Ikon B proved to have about 19% higher COP at 90 deg F and about 26% higher COP at 100 deg F versus R-22. Ikon B had about 20% lower cooling capacity at 90 deg F and about 17% lower cooling capacity at 100 deg F versus R-22 in this system. All results over multiple runs were within 1% relative standard deviation (RSD). All of these

  18. High efficiency stationary hydrogen storage

    SciTech Connect

    Hynek, S.; Fuller, W.; Truslow, S.

    1995-09-01

    Stationary storage of hydrogen permits one to make hydrogen now and use it later. With stationary hydrogen storage, one can use excess electrical generation capacity to power an electrolyzer, and store the resultant hydrogen for later use or transshipment. One can also use stationary hydrogen as a buffer at fueling stations to accommodate non-steady fueling demand, thus permitting the hydrogen supply system (e.g., methane reformer or electrolyzer) to be sized to meet the average, rather than the peak, demand. We at ADL designed, built, and tested a stationary hydrogen storage device that thermally couples a high-temperature metal hydride to a phase change material (PCM). The PCM captures and stores the heat of the hydriding reaction as its own heat of fusion (that is, it melts), and subsequently returns that heat of fusion (by freezing) to facilitate the dehydriding reaction. A key component of this stationary hydrogen storage device is the metal hydride itself. We used nickel-coated magnesium powder (NCMP) - magnesium particles coated with a thin layer of nickel by means of chemical vapor deposition (CVD). Magnesium hydride can store a higher weight fraction of hydrogen than any other practical metal hydride, and it is less expensive than any other metal hydride. We designed and constructed an experimental NCM/PCM reactor out of 310 stainless steel in the form of a shell-and-tube heat exchanger, with the tube side packed with NCMP and the shell side filled with a eutectic mixture of NaCL, KCl, and MgCl{sub 2}. Our experimental results indicate that with proper attention to limiting thermal losses, our overall efficiency will exceed 90% (DOE goal: >75%) and our overall system cost will be only 33% (DOE goal: <50%) of the value of the delivered hydrogen. It appears that NCMP can be used to purify hydrogen streams and store hydrogen at the same time. These prospects make the NCMP/PCM reactor an attractive component in a reformer-based hydrogen fueling station.

  19. Wood anatomy reveals high theoretical hydraulic conductivity and low resistance to vessel implosion in a Cretaceous fossil forest from northern Mexico.

    PubMed

    Martínez-Cabrera, Hugo I; Estrada-Ruiz, Emilio

    2014-01-01

    The Olmos Formation (upper Campanian), with over 60 angiosperm leaf morphotypes, is Mexico's richest Cretaceous flora. Paleoclimate leaf physiognomy estimates indicate that the Olmos paleoforest grew under wet and warm conditions, similar to those present in modern tropical rainforests. Leaf surface area, tree size and climate reconstructions suggest that this was a highly productive system. Efficient carbon fixation requires hydraulic efficiency to meet the evaporative demands of the photosynthetic surface, but it comes at the expense of increased risk of drought-induced cavitation. Here we tested the hypothesis that the Olmos paleoforest had high hydraulic efficiency, but was prone to cavitation. We characterized the hydraulic properties of the Olmos paleoforest using theoretical conductivity (Ks), vessel composition (S) and vessel fraction (F), and measured drought resistance using vessel implosion resistance (t/b)h(2) and the water potential at which there is 50% loss of hydraulic conductivity (P50). We found that the Olmos paleoforest had high hydraulic efficiency, similar to that present in several extant tropical-wet or semi-deciduous forest communities. Remarkably, the fossil flora had the lowest (t/b)h(2), which, together with low median P50 (-1.9 MPa), indicate that the Olmos paleoforest species were extremely vulnerable to drought-induced cavitation. Our findings support paleoclimate inferences from leaf physiognomy and paleoclimatic models suggesting it represented a highly productive wet tropical rainforest. Our results also indicate that the Olmos Formation plants had a large range of water conduction strategies, but more restricted variation in cavitation resistance. These straightforward methods for measuring hydraulic properties, used herein for the first time, can provide useful information on the ecological strategies of paleofloras and on temporal shifts in ecological function of fossil forests chronosequences.

  20. Wood Anatomy Reveals High Theoretical Hydraulic Conductivity and Low Resistance to Vessel Implosion in a Cretaceous Fossil Forest from Northern Mexico

    PubMed Central

    Martínez-Cabrera, Hugo I.; Estrada-Ruiz, Emilio

    2014-01-01

    The Olmos Formation (upper Campanian), with over 60 angiosperm leaf morphotypes, is Mexico's richest Cretaceous flora. Paleoclimate leaf physiognomy estimates indicate that the Olmos paleoforest grew under wet and warm conditions, similar to those present in modern tropical rainforests. Leaf surface area, tree size and climate reconstructions suggest that this was a highly productive system. Efficient carbon fixation requires hydraulic efficiency to meet the evaporative demands of the photosynthetic surface, but it comes at the expense of increased risk of drought-induced cavitation. Here we tested the hypothesis that the Olmos paleoforest had high hydraulic efficiency, but was prone to cavitation. We characterized the hydraulic properties of the Olmos paleoforest using theoretical conductivity (Ks), vessel composition (S) and vessel fraction (F), and measured drought resistance using vessel implosion resistance and the water potential at which there is 50% loss of hydraulic conductivity (P50). We found that the Olmos paleoforest had high hydraulic efficiency, similar to that present in several extant tropical-wet or semi-deciduous forest communities. Remarkably, the fossil flora had the lowest , which, together with low median P50 (−1.9 MPa), indicate that the Olmos paleoforest species were extremely vulnerable to drought-induced cavitation. Our findings support paleoclimate inferences from leaf physiognomy and paleoclimatic models suggesting it represented a highly productive wet tropical rainforest. Our results also indicate that the Olmos Formation plants had a large range of water conduction strategies, but more restricted variation in cavitation resistance. These straightforward methods for measuring hydraulic properties, used herein for the first time, can provide useful information on the ecological strategies of paleofloras and on temporal shifts in ecological function of fossil forests chronosequences. PMID:25279992

  1. High efficiency ground data transmission

    NASA Technical Reports Server (NTRS)

    Dickinson, W. B.

    1973-01-01

    It is demonstrated that state-of-the-art communications technology can be implemented and reliably operated on a global basis to increase the transmission rates and efficiencies on circuits with bandwidths greater than the typical speech channel. Optimization is affected by optimum clock recovery procedures, multilevel pulse amplitude modulation, single sideband amplitude modulation, transversal filter equalizers, data scrambling, and active compensation for phase instability.

  2. High efficiency thermionic converter studies

    NASA Technical Reports Server (NTRS)

    Huffman, F. N.; Sommer, A. H.; Balestra, C. L.; Briere, T. R.; Lieb, D.; Oettinger, P. E.; Goodale, D. B.

    1977-01-01

    Research in thermionic energy conversion technology is reported. The objectives were to produce converters suitable for use in out of core space reactors, radioisotope generators, and solar satellites. The development of emitter electrodes that operate at low cesium pressure, stable low work function collector electrodes, and more efficient means of space charge neutralization were investigated to improve thermionic converter performance. Potential improvements in collector properties were noted with evaporated thin film barium oxide coatings. Experiments with cesium carbonate suggest this substance may provide optimum combinations of cesium and oxygen for thermionic conversion.

  3. High-efficiency solar concentrator

    NASA Technical Reports Server (NTRS)

    Lansing, F. L.; Dorman, J.

    1976-01-01

    A new type of solar concentrator is presented using liquid lenses and simple translational tracking mechanism. The concentrator achieves a 100:1 nominal concentration ratio and is compared in performance with a flat-plate collector having two sheets of glazing and non-selective coating. The results of the thermal analysis show that higher temperatures can be obtained with the concentrator than is possible with the non-concentrator flat-plate type. Furthermore, the thermal efficiency far exceeds that of the comparative flat-plate type for all operating conditions.

  4. High-efficiency solar concentrator

    NASA Technical Reports Server (NTRS)

    Lansing, F. L.; Dorman, J.

    1980-01-01

    A new type of solar concentrator is presented using liquid lenses and simple translational tracking mechanism. The concentrator achieves a 100:1 nominal concentration ratio and is compared in performance with a flat-plate collector having two sheets of glazing and non-selective coating. The results of the thermal analysis show that higher temperatures can be obtained with the concentrator than is possible with the non-concentrator flat-plate type. Furthermore, the thermal efficiency far exceeds that of the comparative flat-plate type for all operating conditions.

  5. High-resolution global fossil fuel CO2 emissions for 1992 to 2010 using integrated in-situ and remotely sensed data in a fossil fuel data assimilation system

    NASA Astrophysics Data System (ADS)

    Asefi-Najafabady, S.; Gurney, K. R.; Rayner, P.; Huang, J.; Song, Y.

    2012-12-01

    provide an approximate location and magnitude for fossil fuel CO2 emissions. Some emitting sectors, such as power plant emissions and heavy industry, are not coincident with where people live or lights are on. Therefore, for better accuracy, we used direct emissions information from power stations as a constraint to the FFDAS estimation. We present this new high resolution, multiyear emissions data product with analysis of the space/time patterns, trends and posterior uncertainty. We also compare the FFDAS results to the "bottom-up" high resolution fossil fuel CO2 emissions estimation generated by the Vulcan Project in the United States. Finally, we examine the sensitivity of the results to differences in the procedures used to generate the improved multiyear nightlights time series.

  6. A high resolution stratigraphic framework for the remarkable fossil cetacean assemblage of the Miocene/Pliocene Pisco Formation, Peru

    NASA Astrophysics Data System (ADS)

    Brand, Leonard; Urbina, Mario; Chadwick, Arthur; DeVries, Thomas J.; Esperante, Raul

    2011-04-01

    The Miocene/Pliocene Pisco Formation of Peru contains a rich marine vertebrate fossil record, providing a unique opportunity for the study of paleoecology and evolution, along with the sedimentological context of the fossils. The lack of a high-resolution stratigraphic framework has hampered such study. In this paper we develop the needed stratigraphy for the areas in the Pisco Formation where most of the vertebrate paleontological research is occurring. In the Ica Valley and in the vicinity of Lomas, series of lithologically or paleontologically unique marker beds were identified. These were walked out and documented with GPS technology. Measured sections connecting these marker beds provide a stratigraphic framework for the areas studied. GPS locations, maps of the marker beds on aerial photographs, and outcrop photographs allow field determination of the stratigraphic positions of study areas.

  7. 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.

  8. 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.

  9. High Performance Rh2P Electrocatalyst for Efficient Water Splitting.

    PubMed

    Duan, Haohong; Li, Dongguo; Tang, Yan; He, Yang; Fang, Ji Shu; Wang, Rongyue; Lv, Haifeng; Lopes, Pietro P; Paulikas, Arvydas P; Li, Haoyi; Mao, Scott X; Wang, Chong-Min; Markovic, Nenad M; Li, Jun; Stamenkovic, Vojislav R; Li, Yadong

    2017-03-26

    Search for active, stable and cost-efficient electrocataltysts for hydrogen production via water splitting could make substantial impact to the energy technologies that do not rely on fossil fuels. Here we report the synthesis of rhodium phosphide electrocatalyst with low metal loading in the form of nanocubes (NCs) dispersed in high surface area carbon (Rh2P/C) by a facile solvo-thermal approach. The Rh2P/C exhibit remarkable performance for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) compared to Rh/C and Pt/C catalysts. The atomic structure of the Rh2P NCs was directly observed by annular dark-field scanning transmission electron microscopy (ADF-STEM), which revealed phosphorous-rich outermost atomic layer. Combined experimental and computational studies suggest that surface phosphorous plays crucial role in determining the robust catalyst properties.

  10. Efficient high density train operations

    DOEpatents

    Gordon, Susanna P.; Evans, John A.

    2001-01-01

    The present invention provides methods for preventing low train voltages and managing interference, thereby improving the efficiency, reliability, and passenger comfort associated with commuter trains. An algorithm implementing neural network technology is used to predict low voltages before they occur. Once voltages are predicted, then multiple trains can be controlled to prevent low voltage events. Further, algorithms for managing inference are presented in the present invention. Different types of interference problems are addressed in the present invention such as "Interference. During Acceleration", "Interference Near Station Stops", and "Interference During Delay Recovery." Managing such interference avoids unnecessary brake/acceleration cycles during acceleration, immediately before station stops, and after substantial delays. Algorithms are demonstrated to avoid oscillatory brake/acceleration cycles due to interference and to smooth the trajectories of closely following trains. This is achieved by maintaining sufficient following distances to avoid unnecessary braking/accelerating. These methods generate smooth train trajectories, making for a more comfortable ride, and improve train motor reliability by avoiding unnecessary mode-changes between propulsion and braking. These algorithms can also have a favorable impact on traction power system requirements and energy consumption.

  11. High Efficiency Thermoelectric Generator: Integration

    DTIC Science & Technology

    2011-02-25

    included: − material barriers such as thermal blankets, glass bubbles and aerogels , − encapsulation with high molecular weight gases (e.g. Xenon... aerogels impregnated with radiation scattering particles (investigated at the thermoelectric group in the NASA Jet Propulsion Laboratory). Thrust

  12. A Fossil DNA Based High Resolution Record of Holocene Planktonic Taxa and Environmental Change in the Black Sea

    NASA Astrophysics Data System (ADS)

    Coolen, M. J.; Saenz, J. P.; Trowbridge, N.; Eglinton, T.

    2007-12-01

    A standard approach to study past planktonic taxa which carry information about past environments and climate variability is the microscopic determination and enumeration of microfossils. However, most planktonic taxa are soft-bodied and in cases where microfossils are absent or difficult to identify, chemical fossils (lipid biomarkers) can be used as paleoecological tools. Nevertheless, most lipids are not very specific, multiple sources are possible, or their biological source remains unknown. Recently, we and others have shown that under excellent preservation conditions, the analysis of preserved genetic signatures (fossil DNA) offers great potential to study past planktonic communities, including soft-bodied species, at the unprecedented species- and even strain-level (this work). Given the dramatic shifts in hydrography and the present anoxia that permeates most of the water column which promotes preservation of cellular materials, the Black Sea is an excellent setting to study the ancient species composition based on fossil DNA. We developed a high temporal resolution (50-100 yr) fossil DNA and lipid biomarker based stratigraphic record of planktonic community structure in the Black Sea spanning the complete Holocene development from the first post-glacial input of Mediterranean waters in the paleo-lacustrine Black Sea to the present. Preserved genetic markers for microbial communities dwelling at the surface (algal primary producers and zooplankton), the suboxic layer (marine Crenarchaeota), and the sulfidic chemocline (green sulfur bacteria) were targeted to provide information on past environmental change in the Black Sea. Specifically, we targeted markers that contributed to our understanding of past surface water temperature, salinity and stratification. Where possible, a side-by-side phylogenetic and lipid biomarker analyses was performed in order to carefully assess the validity of utilizing the former as proxies of a given biological input. As the

  13. 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.

  14. High-Efficiency Power Module

    NASA Technical Reports Server (NTRS)

    Simons, Rainee N. (Inventor); Wintucky, Edwin G. (Inventor)

    2015-01-01

    One or more embodiments of the present invention pertain to an all solid-state microwave power module. The module includes a plurality of solid-state amplifiers configured to amplify a signal using a low power stage, a medium power stage, and a high power stage. The module also includes a power conditioner configured to activate a voltage sequencer (e.g., bias controller) when power is received from a power source. The voltage sequencer is configured to sequentially apply voltage to a gate of each amplifier and sequentially apply voltage to a drain of each amplifier.

  15. High-Efficiency Power Module

    NASA Technical Reports Server (NTRS)

    Simons, Rainee N (Inventor); Wintucky, Edwin G (Inventor)

    2013-01-01

    One or more embodiments of the present invention pertain to an all solid-state microwave power module. The module includes a plurality of solid-state amplifiers configured to amplify a signal using a low power stage, a medium power stage, and a high power stage. The module also includes a power conditioner configured to activate a voltage sequencer (e.g., bias controller) when power is received from a power source. The voltage sequencer is configured to sequentially apply voltage to a gate of each amplifier and sequentially apply voltage to a drain of each amplifier.

  16. Fossil Horses

    NASA Astrophysics Data System (ADS)

    MacFadden, Bruce J.

    1994-06-01

    The family Equidae have an extensive fossil record spanning the past 58 million years, and the evolution of the horse has frequently been used as a classic example of long-term evolution. In recent years, however, there have been many important discoveries of fossil horses, and these, in conjunction with such new methods as cladistics, and techniques such as precise geochronology, have allowed us to achieve a much greater understanding of the evolution and biology of this important group. This book synthesizes the large body of data and research relevant to an understanding of fossil horses from several disciplines including biology, geology and paleontology. Using horses as the central theme, the author weaves together in the text such topics as modern geochronology, paleobiogeography, climate change, evolution and extinction, functional morphology, and population biology during the Cenozoic period. This book will be exciting reading for researchers and graduate students in vertebrate paleontology, evolution, and zoology.

  17. High Efficiency Microwave Power Amplifier (HEMPA) Design

    NASA Technical Reports Server (NTRS)

    Sims, W. Herbert

    2004-01-01

    This paper will focus on developing an exotic switching technique that enhances the DC-to-RF conversion efficiency of microwave power amplifiers. For years, switching techniques implemented in the 10 kHz to 30 MHz region have resulted in DC-to-RF conversion efficiencies of 90-95-percent. Currently amplifier conversion efficiency, in the 2-3 GHz region approaches, 10-20-percent. Using a combination of analytical modeling and hardware testing, a High Efficiency Microwave Power Amplifier was built that demonstrated conversion efficiencies four to five times higher than current state of the art.

  18. Multicolor, High Efficiency, Nanotextured LEDs

    SciTech Connect

    Jung Han; Arto Nurmikko

    2011-09-30

    We report on research results in this project which synergize advanced material science approaches with fundamental optical physics concepts pertaining to light-matter interaction, with the goal of solving seminal problems for the development of very high performance light emitting diodes (LEDs) in the blue and green for Solid State Lighting applications. Accomplishments in the duration of the contract period include (i) heteroepitaxy of nitrogen-polar LEDs on sapphire, (ii) heteroepitaxy of semipolar (11{bar 2}2) green LEDs on sapphire, (iii) synthesis of quantum-dot loaded nanoporous GaN that emits white light without phosphor conversion, (iv) demonstration of the highest quality semipolar (11{bar 2}2) GaN on sapphire using orientation-controlled epitaxy, (v) synthesis of nanoscale GaN and InGaN medium, and (vi) development of a novel liftoff process for manufacturing GaN thin-film vertical LEDs. The body of results is presented in this report shows how a solid foundation has been laid, with several noticeable accomplishments, for innovative research, consistent with the stated milestones.

  19. High Efficiency Lithium-Thionyl Chloride Cell.

    DTIC Science & Technology

    1982-04-01

    AD-Al14 672 HONEYWELL POWER SOURCES CENTER HORSHAM PA F/S 10/3 HIGH EFFICIENCY LITHIUM - THIONYL CHLORIDE CELLo(U) APR 82 N DODDAPANEN! OAAK20-81-C...CHART NATIONAl BUREAU OF STANDARDS 1963 A Research and Development Technical Report DELET-TR-81-0381-3 HIGH EFFICIENCY LITHIUM - THIONYL CHLORIDE CELL...reverse aide it necessary and Identify by block number) Thionyl chloride , lithium , high discharge rates, low temperatures, catalysis, cyclic

  20. Advanced Nanomaterials for High-Efficiency Solar Cells

    SciTech Connect

    Chen, Junhong

    2013-11-29

    Energy supply has arguably become one of the most important problems facing humankind. The exponential demand for energy is evidenced by dwindling fossil fuel supplies and record-high oil and gas prices due to global population growth and economic development. This energy shortage has significant implications to the future of our society, in addition to the greenhouse gas emission burden due to consumption of fossil fuels. Solar energy seems to be the most viable choice to meet our clean energy demand given its large scale and clean/renewable nature. However, existing methods to convert sun light into electricity are not efficient enough to become a practical alternative to fossil fuels. This DOE project aims to develop advanced hybrid nanomaterials consisting of semiconductor nanoparticles (quantum dots or QDs) supported on graphene for cost-effective solar cells with improved conversion efficiency for harvesting abundant, renewable, clean solar energy to relieve our global energy challenge. Expected outcomes of the project include new methods for low-cost manufacturing of hybrid nanostructures, systematic understanding of their properties that can be tailored for desired applications, and novel photovoltaic cells. Through this project, we have successfully synthesized a number of novel nanomaterials, including vertically-oriented graphene (VG) sheets, three-dimensional (3D) carbon nanostructures comprising few-layer graphene (FLG) sheets inherently connected with CNTs through sp{sup 2} carbons, crumpled graphene (CG)-nanocrystal hybrids, CdSe nanoparticles (NPs), CdS NPs, nanohybrids of metal nitride decorated on nitrogen-doped graphene (NG), QD-carbon nanotube (CNT) and QD-VG-CNT structures, TiO{sub 2}-CdS NPs, and reduced graphene oxide (RGO)-SnO{sub 2} NPs. We further assembled CdSe NPs onto graphene sheets and investigated physical and electronic interactions between CdSe NPs and the graphene. Finally we have demonstrated various applications of these

  1. Very High Efficiency Solar Cell Modules

    SciTech Connect

    Barnett, A.; Kirkpatrick, D.; Honsberg, C.; Moore, D.; Wanlass, M.; Emery, K.; Schwartz, R.; Carlson, D.; Bowden, S.; Aiken, D.; Gray, A.; Kurtz, S.; Kazmerski, L., et al

    2009-01-01

    The Very High Efficiency Solar Cell (VHESC) program is developing integrated optical system - PV modules for portable applications that operate at greater than 50% efficiency. We are integrating the optical design with the solar cell design, and have entered previously unoccupied design space. Our approach is driven by proven quantitative models for the solar cell design, the optical design, and the integration of these designs. Optical systems efficiency with an optical efficiency of 93% and solar cell device results under ideal dichroic splitting optics summing to 42.7 {+-} 2.5% are described.

  2. Multi Band Gap High Efficiency Converter (RAINBOW)

    NASA Technical Reports Server (NTRS)

    Bekey, I.; Lewis, C.; Phillips, W.; Shields, V.; Stella, P.

    1997-01-01

    The RAINBOW multi band gap system represents a unique combination of solar cells, concentrators and beam splitters. RAINBOW is a flexible system which can readily expand as new high efficiency components are developed.

  3. Junior High Gets Energy Efficient VAV System

    ERIC Educational Resources Information Center

    Modern Schools, 1977

    1977-01-01

    Minnesota's Isanti Junior High, designed with an energy efficient variable air volume system, is an innovative school selected for display at the 1977 Exhibition of School Architecture in Las Vegas. (Author/MLF)

  4. High efficiency flat plate solar energy collector

    SciTech Connect

    Butler, R. F.

    1985-04-30

    A concentrating flat plate collector for the high efficiency collection of solar energy. Through an arrangement of reflector elements, incoming solar radiation, either directly or after reflection from the reflector elements, impinges upon both surfaces of a collector element.

  5. 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

  6. 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.

  7. High efficiency quantum cascade laser frequency comb

    NASA Astrophysics Data System (ADS)

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

    2017-03-01

    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.

  8. Education Program on Fossil Resources Including Coal

    NASA Astrophysics Data System (ADS)

    Usami, Masahiro

    Fossil fuels including coal play a key role as crucial energies in contributing to economic development in Asia. On the other hand, its limited quantity and the environmental problems causing from its usage have become a serious global issue and a countermeasure to solve such problems is very much demanded. Along with the pursuit of sustainable development, environmentally-friendly use of highly efficient fossil resources should be therefore, accompanied. Kyushu-university‧s sophisticated research through long years of accumulated experience on the fossil resources and environmental sectors together with the advanced large-scale commercial and empirical equipments will enable us to foster cooperative research and provide internship program for the future researchers. Then, this program is executed as a consignment business from the Ministry of Economy, Trade and Industry from 2007 fiscal year to 2009 fiscal year. The lecture that uses the textbooks developed by this program is scheduled to be started a course in fiscal year 2010.

  9. Important loss mechanisms in high-efficiency solar cells

    NASA Technical Reports Server (NTRS)

    Sah, C. T.

    1984-01-01

    A study was conducted to identify loss mechanisms in high efficiency silicon solar cells. The following were considered: (1) recombination loss mechanisms; (2) high efficiency cells; (3) very high efficiency cells; and (4) ultra high efficiency cells.

  10. High-efficiency silicon solar cells

    NASA Technical Reports Server (NTRS)

    Green, M. A.; Blakers, A. W.; Shi, J.; Keller, E. M.; Wenham, S. R.

    1984-01-01

    Silicon solar cells are described which operate at energy conversion efficiencies independently measured at 18.7 percent under standard terrestrial test conditions (AM1.5, 100 mW/sq cm, 28 C). These are apparently the most efficient silicon cells fabricated to date. The high-efficiency results from a combination of high open-circuit voltage due to the careful attention paid to the passivation of the top surface of the cell, high fill factor due to the high open-circuit voltage and low parasitic resistance losses, and high short-circuit current density due to the use of shallow diffusions, a low grid coverage, and an optimized double layer antireflection coating.

  11. The future of high efficiency solar cells

    NASA Technical Reports Server (NTRS)

    Fan, J. C. C.

    1984-01-01

    Research approaches to obtain solar cell modules with 1 sun efficiencies of 20-30 percent at air mass 1 are now well understood. Such high efficiency modules should become available in the near future. It can be expected that these modules will be extensively used in terrestrial power generation, space power generation, and consumer electronics. To achieve practical module efficiencies significantly above 30 percent, it will be necessary to employ concepts other than spectral splitting, such as spectral compression and broad band detection. A major breakthrough in these areas is not anticipated at this time.

  12. High efficiency wraparound contact solar cells /HEWACS/

    NASA Technical Reports Server (NTRS)

    Gillanders, M.; Opjorden, R.

    1980-01-01

    A cell technology, producing high efficiency wrap-around contact solar cells (HEWACS), with both electrical contacts on the back and AMO conversion efficiencies of almost 15%, is presented. A flow chart indicating the baseline process sequence along with the process changes is given. Tests checking for coating delamination and contact integrity, those measuring contact strength, and thermal cycle tests, successfully demonstrated that this cell technology is ready to be moved to the pilot production stage.

  13. Efficient synthesis of highly substituted tetrahydroindazolone derivatives.

    PubMed

    Scala, Angela; Piperno, Anna; Risitano, Francesco; Cirmi, Santa; Navarra, Michele; Grassi, Giovanni

    2015-08-01

    A straightforward and efficient method for the synthesis of novel highly substituted and diversely functionalized indazolone derivatives has been developed. The transformation consists of a cyclocondensation of selected 1,3,3'-tricarbonyls with monosubstituted hydrazines. The starting β-triketones were prepared by an efficient chemo- and regioselective method under MW irradiation, exploiting the oxazolone chemistry. The reaction is easily accomplished under mild conditions and appears versatile, providing a synthetic diversification method with potential for drug-like compounds preparation.

  14. Mud fossils

    USGS Publications Warehouse

    ,

    1997-01-01

    At the close of the 18th century, the haze of fantasy and mysticism that tended to obscure the true nature of the Earth was being swept away. Careful studies by scientists showed that rocks had diverse origins. Some rock layers, containing clearly identifiable fossil remains of fish and other forms of aquatic animal and plant life, originally formed in the ocean. Other layers, consisting of sand grains winnowed clean by the pounding surf, obviously formed as beach deposits that marked the shorelines of ancient seas.

  15. 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.

  16. Highly efficient heralding of entangled single photons.

    PubMed

    Ramelow, Sven; Mech, Alexandra; Giustina, Marissa; Gröblacher, Simon; Wieczorek, Witlef; Beyer, Jörn; Lita, Adriana; Calkins, Brice; Gerrits, Thomas; Nam, Sae Woo; Zeilinger, Anton; Ursin, Rupert

    2013-03-25

    Single photons are an important prerequisite for a broad spectrum of quantum optical applications. We experimentally demonstrate a heralded single-photon source based on spontaneous parametric down-conversion in collinear bulk optics, and fiber-coupled bolometric transition-edge sensors. Without correcting for background, losses, or detection inefficiencies, we measure an overall heralding efficiency of 83%. By violating a Bell inequality, we confirm the single-photon character and high-quality entanglement of our heralded single photons which, in combination with the high heralding efficiency, are a necessary ingredient for advanced quantum communication protocols such as one-sided device-independent quantum key distribution.

  17. Advanced high efficiency wraparound contact solar cell

    NASA Technical Reports Server (NTRS)

    Scott-Monck, J. A.; Uno, F. M.; Thornhill, J. W.

    1977-01-01

    A significant advancement in the development of thin high efficiency wraparound contact silicon solar cells has been made by coupling space and terrestrial processing procedures. Although this new method for fabricating cells has not been completely reduced to practice, some of the initial cells have delivered over 20 mW/sq cm when tested at 25 C under AMO intensity. This approach not only yields high efficiency devices, but shows promise of allowing complete freedom of choice in both the location and size of the wraparound contact pad area

  18. Advanced high efficiency wraparound contact solar cell

    NASA Technical Reports Server (NTRS)

    Scott-Monck, J. A.; Uno, F. M.; Thornhill, J. W.

    1977-01-01

    A significant advancement in the development of thin high efficiency wraparound contact silicon solar cells has been made by coupling space and terrestrial processing procedures. Although this new method for fabricating cells has not been completely reduced to practice, some of the initial cells have delivered over 20 mW/sq cm when tested at 25 C under AMO intensity. This approach not only yields high efficiency devices, but shows promise of allowing complete freedom of choice in both the location and size of the wraparound contact pad area.

  19. Measure Guideline. High Efficiency Natural Gas Furnaces

    SciTech Connect

    Brand, L.; Rose, W.

    2012-10-01

    This measure guideline covers installation of high-efficiency gas furnaces, including: 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.

  20. Measure Guideline: High Efficiency Natural Gas Furnaces

    SciTech Connect

    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.

  1. Proposal for superstructure based high efficiency photovoltaics

    NASA Technical Reports Server (NTRS)

    Wagner, M.; Leburton, J. P.

    1986-01-01

    A novel class of cascade structures is proposed which features multijunction upper subcells, referred to as superstructure high-efficiency photovoltaics (SHEPs). The additional junctions enhance spectral response and improve radiation tolerance by reducing bulk recombination losses. This is important because ternary III-V alloys, which tend to have short minority-carrier diffusion lengths, are the only viable materials for the high-bandgap upper subcells required for cascade solar cells. Realistic simulations of AlGaAs SHEPs show that one-sun AM0 efficiencies in excess of 26 percent are possible.

  2. Interface modification for highly efficient organic photovoltaics

    NASA Astrophysics Data System (ADS)

    Steim, Roland; Choulis, Stelios A.; Schilinsky, Pavel; Brabec, Christoph J.

    2008-03-01

    We present highly efficient inverted polymer:fullerene bulk-heterojunction solar cells by incorporation of a nanoscale organic interfacial layer between the indium tin oxide (ITO) and the metal oxide electron-conducting layer. We demonstrate that stacking of solution-processed organic and metal oxide interfacial layers gives highly charged selective low ohmic cathodes. The incorporation of a polyoxyethylene tridecyl ether interfacial layer between ITO and solution-processed titanium oxide (TiOx) raised the power conversion efficiency of inverted organic photovoltaics to 3.6%, an improvement of around 15% in their performance over comparable devices without the organic interfacial layer.

  3. High efficiency, variable geometry, centrifugal cryogenic pump

    SciTech Connect

    Forsha, M.D.; Nichols, K.E.; Beale, C.A.

    1994-12-31

    A centrifugal cryogenic pump has been developed which has a basic design that is rugged and reliable with variable speed and variable geometry features that achieve high pump efficiency over a wide range of head-flow conditions. The pump uses a sealless design and rolling element bearings to achieve high reliability and the ruggedness to withstand liquid-vapor slugging. The pump can meet a wide range of variable head, off-design flow requirements and maintain design point efficiency by adjusting the pump speed. The pump also has features that allow the impeller and diffuser blade heights to be adjusted. The adjustable height blades were intended to enhance the pump efficiency when it is operating at constant head, off-design flow rates. For small pumps, the adjustable height blades are not recommended. For larger pumps, they could provide off-design efficiency improvements. This pump was developed for supercritical helium service, but the design is well suited to any cryogenic application where high efficiency is required over a wide range of head-flow conditions.

  4. Enhanced High Temperature Corrosion Resistance in Advanced Fossil Energy Systems by Nano-Passive Layer Formation

    SciTech Connect

    Arnold R. Marder

    2007-06-14

    Due to their excellent corrosion resistance, iron aluminum alloys are currently being considered for use as weld claddings in fossil fuel fired power plants. The susceptibility to hydrogen cracking of these alloys at higher aluminum concentrations has highlighted the need for research into the effect of chromium additions on the corrosion resistance of lower aluminum alloys. In the present work, three iron aluminum alloys were exposed to simulated coal combustion environments at 500 C and 700 C for both short (100 hours) and long (5,000 hours) isothermal durations. Scanning electron microscopy was used to analyze the corrosion products. All alloys exhibited excellent corrosion resistance in the short term tests. For longer exposures, increasing the aluminum concentration was beneficial to the corrosion resistance. The addition of chromium to the binary iron aluminum alloy prevented the formation iron sulfide and resulted in lower corrosion kinetics. A classification of the corrosion products that developed on these alloys is presented. Scanning transmission electron microscopy (STEM) of the as-corroded coupons revealed that chromium was able to form chromium sulfides only on the higher aluminum alloy, thereby preventing the formation of deleterious iron sulfides. When the aluminum concentration was too low to permit selective oxidation of only aluminum (upon initial exposure to the corrosion environment), the formation of chromium oxide alongside the aluminum oxide led to depletion of chromium beneath the oxide layer. Upon penetration of sulfur through the oxide into this depletion layer, iron sulfides (rather than chromium sulfides) were found to form on the low aluminum alloy. Thus, it was found in this work that the role of chromium on alloy corrosion resistance was strongly effected by the aluminum concentration of the alloy. STEM analysis also revealed the encapsulation of external iron sulfide products with a thin layer of aluminum oxide, which may provide a

  5. High efficiency novel window air conditioner

    SciTech Connect

    Bansal, Pradeep

    2015-01-01

    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, and 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.

  6. High efficiency novel window air conditioner

    DOE PAGES

    Bansal, Pradeep

    2015-01-01

    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

  7. 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.

  8. Trace fossils and ichnofabrics on the Lower Muschelkalk carbonate ramp (Triassic) of Germany: tool for high-resolution sequence stratigraphy

    NASA Astrophysics Data System (ADS)

    Knaust, D.

    In the German Triassic of Thuringia, the Lower Muschelkalk sequence can be subdivided by application of ichnological methods. Three ichnofacies with five ichnofabrics are described. In accordance with the lithological features, trace fossils are found to defining parasequences on the basis of a regular change of bioturbation. Furthermore, it is possible to establish deepening-upward cycles. The reconstruction of parasequences allows the establishment of a high-resolution sequence stratigraphy. The position of the maximum flooding surface can be identified in the Terebratula Member and is developed in a condensed interval. The most significant of the additional major marine flooding surfaces is found at the top of the Upper Oolith Bed, characterized by lithostratigraphy, ichnology, biostratigraphy and parasequence thickness trends.

  9. Total Summer Precipitation Estimated for the Early Eocene Arctic from High-Resolution Intra-ring Analyses of Fossil Wood

    NASA Astrophysics Data System (ADS)

    Schubert, B.; Jahren, A.

    2010-12-01

    During the Early Eocene (~53 - 54.5 Ma) Ellesmere Island was home to a forested ecosystem north of the Arctic Circle (ca. 76o N paleolatitude). Although several estimates exist for Eocene pCO2 levels, temperature, and relative humidity in Arctic environments, quantitative estimates of precipitation have been elusive. We present here a new method for estimating mean-annual precipitation levels from the amplitude of the annual shift in δ13C values seen across the rings of evergreen trees. Both temperature and precipitation affect the δ13C value of plant tissue, and a combination of these factors is recorded in bulk wood. Inspection of high-resolution δ13C profiles across tree-rings from nine evergreen species growing in ten different locations around the world revealed a strong relationship (R2 = 0.98) between the mean δ13C peak-height and the ratio of total summer precipitation (cm) to mean summer temperature (oC). Application of this relationship to nearly 700 measurements of δ13C in bulk wood from high-resolution (i.e., ~40 µm) sampling of evergreen fossil wood, in combination with temperature estimates from geochemical proxies, yielded estimates for total summer precipitation in excess of 90 cm. These conditions are considerably wetter than evergreen forests found at today's mid-latitudes (e.g., the pine forests of Siberia have ~30 cm of total summer precipitation; the spruce forests of Germany and Northern Italy have ~40 - 60 cm of total summer precipitation). We compare our results to Eocene paleoprecipitation estimates based on leaf area analysis of fossil leaves collected from similar sites and discuss the implications for global water transport.

  10. High Efficiency Solar Integrated Roof Membrane Product

    SciTech Connect

    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.

  11. A Biological Time Capsule. Fossil Fish.

    ERIC Educational Resources Information Center

    Dolph, Gary E.; Dolph, Laura L.

    1990-01-01

    Described is an activity where students prepare high-quality fossil specimens to demonstrate the theory of evolution. The technique needed for fossil removal, the geologic and paleoclimatic setting, and the fish morphology are discussed. (KR)

  12. Efficient circuit triggers high-current, high-voltage pulses

    NASA Technical Reports Server (NTRS)

    Green, E. D.

    1964-01-01

    Modified circuit uses diodes to effectively disconnect the charging resistors from the circuit during the discharge cycle. Result is an efficient parallel charging, high voltage pulse modulator with low voltage rating of components.

  13. High-Temperature High-Efficiency Solar Thermoelectric Generators

    SciTech Connect

    Baranowski, LL; Warren, EL; Toberer, ES

    2014-03-01

    Inspired by recent high-efficiency thermoelectric modules, we consider thermoelectrics for terrestrial applications in concentrated solar thermoelectric generators (STEGs). The STEG is modeled as two subsystems: a TEG, and a solar absorber that efficiently captures the concentrated sunlight and limits radiative losses from the system. The TEG subsystem is modeled using thermoelectric compatibility theory; this model does not constrain the material properties to be constant with temperature. Considering a three-stage TEG based on current record modules, this model suggests that 18% efficiency could be experimentally expected with a temperature gradient of 1000A degrees C to 100A degrees C. Achieving 15% overall STEG efficiency thus requires an absorber efficiency above 85%, and we consider two methods to achieve this: solar-selective absorbers and thermally insulating cavities. When the TEG and absorber subsystem models are combined, we expect that the STEG modeled here could achieve 15% efficiency with optical concentration between 250 and 300 suns.

  14. High-Temperature High-Efficiency Solar Thermoelectric Generators

    NASA Astrophysics Data System (ADS)

    Baranowski, Lauryn L.; Warren, Emily L.; Toberer, Eric S.

    2014-06-01

    Inspired by recent high-efficiency thermoelectric modules, we consider thermoelectrics for terrestrial applications in concentrated solar thermoelectric generators (STEGs). The STEG is modeled as two subsystems: a TEG, and a solar absorber that efficiently captures the concentrated sunlight and limits radiative losses from the system. The TEG subsystem is modeled using thermoelectric compatibility theory; this model does not constrain the material properties to be constant with temperature. Considering a three-stage TEG based on current record modules, this model suggests that 18% efficiency could be experimentally expected with a temperature gradient of 1000°C to 100°C. Achieving 15% overall STEG efficiency thus requires an absorber efficiency above 85%, and we consider two methods to achieve this: solar-selective absorbers and thermally insulating cavities. When the TEG and absorber subsystem models are combined, we expect that the STEG modeled here could achieve 15% efficiency with optical concentration between 250 and 300 suns.

  15. High Efficiency, Low Emission Refrigeration System

    SciTech Connect

    Fricke, Brian A.; Sharma, Vishaldeep

    2016-08-01

    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 high 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 for

  16. Methodologies for high efficiency perovskite solar cells

    NASA Astrophysics Data System (ADS)

    Park, Nam-Gyu

    2016-06-01

    Since the report on long-term durable solid-state perovskite solar cell in 2012, perovskite solar cells based on lead halide perovskites having organic cations such as methylammonium CH3NH3PbI3 or formamidinium HC(NH2)2PbI3 have received great attention because of superb photovoltaic performance with power conversion efficiency exceeding 22 %. In this review, emergence of perovskite solar cell is briefly introduced. Since understanding fundamentals of light absorbers is directly related to their photovoltaic performance, opto-electronic properties of organo lead halide perovskites are investigated in order to provide insight into design of higher efficiency perovskite solar cells. Since the conversion efficiency of perovskite solar cell is found to depend significantly on perovskite film quality, methodologies for fabricating high quality perovskite films are particularly emphasized, including various solution-processes and vacuum deposition method.

  17. Methodologies for high efficiency perovskite solar cells.

    PubMed

    Park, Nam-Gyu

    2016-01-01

    Since the report on long-term durable solid-state perovskite solar cell in 2012, perovskite solar cells based on lead halide perovskites having organic cations such as methylammonium CH3NH3PbI3 or formamidinium HC(NH2)2PbI3 have received great attention because of superb photovoltaic performance with power conversion efficiency exceeding 22 %. In this review, emergence of perovskite solar cell is briefly introduced. Since understanding fundamentals of light absorbers is directly related to their photovoltaic performance, opto-electronic properties of organo lead halide perovskites are investigated in order to provide insight into design of higher efficiency perovskite solar cells. Since the conversion efficiency of perovskite solar cell is found to depend significantly on perovskite film quality, methodologies for fabricating high quality perovskite films are particularly emphasized, including various solution-processes and vacuum deposition method.

  18. High-efficiency silicon concentrator cell commercialization

    SciTech Connect

    Sinton, R.A.; Swanson, R.M.

    1993-05-01

    This report summarizes the first phase of a forty-one month program to develop a commercial, high-efficiency concentrator solar cell and facility for manufacturing it. The period covered is November 1, 1990 to December 31, 1991. This is a joint program between the Electric Power Research Institute (EPRI) and Sandia National Laboratories. (This report is also published by EPRI as EPRI report number TR-102035.) During the first year of the program, SunPower accomplished the following major objectives: (1) a new solar cell fabrication facility, which is called the Cell Pilot Line (CPL), (2) a baseline concentrator cell process has been developed, and (3) a cell testing facility has been completed. Initial cell efficiencies are about 23% for the baseline process. The long-range goal is to improve this efficiency to 27%.

  19. High efficiency electrotransformation of Lactobacillus casei.

    PubMed

    Welker, Dennis L; Hughes, Joanne E; Steele, James L; Broadbent, Jeff R

    2015-01-01

    We investigated whether protocols allowing high efficiency electrotransformation of other lactic acid bacteria were applicable to five strains of Lactobacillus casei (12A, 32G, A2-362, ATCC 334 and BL23). Addition of 1% glycine or 0.9 M NaCl during cell growth, limitation of the growth of the cell cultures to OD600 0.6-0.8, pre-electroporation treatment of cells with water or with a lithium acetate (100 mM)/dithiothreitol (10 mM) solution and optimization of electroporation conditions all improved transformation efficiencies. However, the five strains varied in their responses to these treatments. Transformation efficiencies of 10(6) colony forming units μg(-1) pTRKH2 DNA and higher were obtained with three strains which is sufficient for construction of chromosomal gene knock-outs and gene replacements.

  20. Are the oldest 'fossils', fossils

    NASA Technical Reports Server (NTRS)

    Schopf, J. W.

    1976-01-01

    A comparative statistical study has been carried out on populations of modern algae, Precambrian algal microfossils, the 'organized elements' of the Orgueil carbonaceous meteorite, and the oldest microfossil-like objects now known (spheroidal bodies from the Fig Tree and Onverwacht Groups of the Swaziland Supergroup, South Africa). The distribution patterns exhibited by the more than 3000 m.y.-old Swaziland microstructures bear considerable resemblance to those of the abiotic 'organized elements' but differ rather markedly from those exhibited by younger, assuredly biogenic, populations. Based on these comparisons, it is concluded that the Swaziland spheroids could be, at least in part, of nonbiologic origin; these oldest known fossil-like microstructures should not be regarded as constituting firm evidence of Archean life.

  1. 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.

  2. High Efficiency Thermoelectric Materials and Devices

    NASA Technical Reports Server (NTRS)

    Kochergin, Vladimir (Inventor)

    2013-01-01

    Growth of thermoelectric materials in the form of quantum well super-lattices on three-dimensionally structured substrates provide the means to achieve high conversion efficiency of the thermoelectric module combined with inexpensiveness of fabrication and compatibility with large scale production. Thermoelectric devices utilizing thermoelectric materials in the form of quantum well semiconductor super-lattices grown on three-dimensionally structured substrates provide improved thermoelectric characteristics that can be used for power generation, cooling and other applications..

  3. 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.

  4. High energy efficient solid state laser sources

    NASA Technical Reports Server (NTRS)

    Byer, Robert L.

    1987-01-01

    Diode-laser-pumped solid-state laser oscillators and nonlinear processes were investigated. A new generation on nonplanar oscillator was fabricated, and it is anticipated that passive linewidths will be pushed to the kilohertz regime. A number of diode-pumped laser transitions were demonstrated in the rod configuration. Second-harmonic conversion efficiencies as high as 15% are routinely obtained in a servo-locked external resonant doubling crystal at 15 mW cw input power levels at 1064 nm.

  5. High-efficiency silicon solar cells

    NASA Technical Reports Server (NTRS)

    Olsen, L. C.

    1985-01-01

    Fabrication and characterization of high-efficiency metal insulator, n-p (MINP) cells is described. Particular attention was paid to development of measurement methods for surface recombination and density of surface states. A modified Rosier test structure was used successfully for density of surface states. Silicon oxide and silicon nitride passivants were studied. Heat treatment after plasma enhanced chemical vapor deposition (CVD) of silicon nitride was shown to be beneficial. A more optimum emitter concentration profile was modeled.

  6. High efficiency, long-life photocathodes

    NASA Astrophysics Data System (ADS)

    Ives, Lawrence; Montgomery, Eric; Jensen, Kevin; Collins, George; Marsden, David; Karimov, Rasul; Falce, Lou

    2017-03-01

    Research and development on high efficiency, robust, long-life photocathodes is in progress for accelerator, light source, and other commercial applications. The research is investigating detailed physics of photoemission and developing a computational capability to predict performance. Reservoir technology will significantly increase lifetime and allow recovery from many poisoning events. Better understanding of the physics will impact fabrication techniques to optimize performance. A production facility is under construction to provide improved photocathodes to users.

  7. Bioblendstocks that Enable High Efficiency Engine Designs

    SciTech Connect

    McCormick, Robert L.; Fioroni, Gina M.; Ratcliff, Matthew A.; Zigler, Bradley T.; Farrell, John

    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. 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 diesel fuel

  8. Micronized coal-fired retrofit system for SO{sub x} reduction - Krakow Clean Fossil Fuels and Energy Efficiency Program.

    SciTech Connect

    1996-09-30

    the project proposes to install a new TCS micronized coal-fired heating plant for the Produkcja I Hodowla Roslin Ogrodniczych (PHRO) Greenhouse Complex, Krzeszowice, Poland (about 20 miles west of Krakow). PHRO currently utilizes 14 heavy oil-fired boilers to produce heat for its greenhouse facilities and also home heating to several adjacent apartment housing complexes. The boilers currently burn a high-sulfur content heavy crude oil, called Mazute. The micronized coal fired boiler would (1) provide a significant portion of the heat for PHRO and a portion of the adjacent apartment housing complexes, (2) dramatically reduce sulfur dioxide air pollution emission, while satisfying new Polish air regulations, and (3) provide attractive savings to PHRO, based on the quantity of displaced oil.

  9. Evaluating performance of high efficiency mist eliminators

    SciTech Connect

    Waggoner, Charles A.; Parsons, Michael S.; Giffin, Paxton K.

    2013-07-01

    Processing liquid wastes frequently generates off gas streams with high humidity and liquid aerosols. Droplet laden air streams can be produced from tank mixing or sparging and processes such as reforming or evaporative volume reduction. Unfortunately these wet air streams represent a genuine threat to HEPA filters. High efficiency mist eliminators (HEME) are one option for removal of liquid aerosols with high dissolved or suspended solids content. HEMEs have been used extensively in industrial applications, however they have not seen widespread use in the nuclear industry. Filtering efficiency data along with loading curves are not readily available for these units and data that exist are not easily translated to operational parameters in liquid waste treatment plants. A specialized test stand has been developed to evaluate the performance of HEME elements under use conditions of a US DOE facility. HEME elements were tested at three volumetric flow rates using aerosols produced from an iron-rich waste surrogate. The challenge aerosol included submicron particles produced from Laskin nozzles and super micron particles produced from a hollow cone spray nozzle. Test conditions included ambient temperature and relative humidities greater than 95%. Data collected during testing HEME elements from three different manufacturers included volumetric flow rate, differential temperature across the filter housing, downstream relative humidity, and differential pressure (dP) across the filter element. Filter challenge was discontinued at three intermediate dPs and the filter to allow determining filter efficiency using dioctyl phthalate and then with dry surrogate aerosols. Filtering efficiencies of the clean HEME, the clean HEME loaded with water, and the HEME at maximum dP were also collected using the two test aerosols. Results of the testing included differential pressure vs. time loading curves for the nine elements tested along with the mass of moisture and solid

  10. Development of Nano-crystalline Doped-Ceramic Enabled Fiber Sensors for High Temperature In-Situ Monitoring of Fossil Fuel Gases

    SciTech Connect

    Xiao, Hai; Dong, Junhang; Lin, Jerry; Romero, Van

    2012-03-01

    This is a final technical report for the first project year from July 1, 2005 to Jan 31, 2012 for DoE/NETL funded project DE-FC26-05NT42439: Development of Nanocrystalline Doped-Ceramic Enabled Fiber Sensors for High Temperature In-Situ Monitoring of Fossil Fuel Gases. This report summarizes the technical progresses and achievements towards the development of novel nanocrystalline doped ceramic material-enabled optical fiber sensors for in situ and real time monitoring the gas composition of flue or hot gas streams involved in fossil-fuel based power generation and hydrogen production.

  11. Will My Fossil Float?

    ERIC Educational Resources Information Center

    Riesser, Sharon; Airey, Linda

    1993-01-01

    Explains how young students can be introduced to fossils. Suggests books to read and science activities including "Fossils to Eat" where students make fossils from peanut butter, honey, and powdered milk. (PR)

  12. 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%.

  13. High-efficiency organic electrophosphorescent devices

    NASA Astrophysics Data System (ADS)

    Thompson, Mark E.; Lamansky, Sergey; Djurovich, Peter; Murphy, Drew; Abdel-Razaq, Feras; Forrest, Stephen R.; Baldo, Marc A.; Burrows, Paul E.; Adachi, Chihaya; Zhou, Theodore X.; Michalski, Lech A.; Rajan, Kamala; Brown, Julie J.

    2001-02-01

    We have fabricated saturated red, orange, yellow and green OLEDs, utilizing phosphorescent dopants. Using phosphorescence based emitters we have eliminated the inherent 25% upper limit on emission observed for traditional fluorescence based systems. The quantum efficiencies of these devices are quite good, with measured external efficiencies > 15% and > 40 lum/W (green) in the best devices. The phosphorescent dopants in these devices are heavy metal containing molecules (i.e. Pt, and Ir), prepared as both metalloporphyrins and organometallic complexes. The high level of spin orbit coupling in these metal complexes gives efficient emission from triplet states. In addition to emission from the heavy metal dopant, it is possible to transfer the exciton energy to a fluorescent dye, by Forster energy transfer. The heavy metal dopant in this case acts as a sensitizer, utilizing both singlet and triplet excitons to efficiently pump a fluorescent dye. We discuss the important parameters in designing electrophosphorescent OLEDs as well as their strengths and limitations. Accelerated aging studies, on packaged devices, have shown that phosphorescence based OLEDs can have very long device lifetimes.

  14. 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.

  15. High Efficiency Colloidal Quantum Dot Phosphors

    SciTech Connect

    Kahen, Keith

    2013-12-31

    The project showed that non-Cd containing, InP-based nanocrystals (semiconductor materials with dimensions of ~6 nm) have high potential for enabling next-generation, nanocrystal-based, on chip phosphors for solid state lighting. Typical nanocrystals fall short of the requirements for on chip phosphors due to their loss of quantum efficiency under the operating conditions of LEDs, such as, high temperature (up to 150 °C) and high optical flux (up to 200 W/cm2). The InP-based nanocrystals invented during this project maintain high quantum efficiency (>80%) in polymer-based films under these operating conditions for emission wavelengths ranging from ~530 to 620 nm. These nanocrystals also show other desirable attributes, such as, lack of blinking (a common problem with nanocrystals which limits their performance) and no increase in the emission spectral width from room to 150 °C (emitters with narrower spectral widths enable higher efficiency LEDs). Prior to these nanocrystals, no nanocrystal system (regardless of nanocrystal type) showed this collection of properties; in fact, other nanocrystal systems are typically limited to showing only one desirable trait (such as high temperature stability) but being deficient in other properties (such as high flux stability). The project showed that one can reproducibly obtain these properties by generating a novel compositional structure inside of the nanomaterials; in addition, the project formulated an initial theoretical framework linking the compositional structure to the list of high performance optical properties. Over the course of the project, the synthetic methodology for producing the novel composition was evolved to enable the synthesis of these nanomaterials at a cost approximately equal to that required for forming typical conventional nanocrystals. Given the above results, the last major remaining step prior to scale up of the nanomaterials is to limit the oxidation of these materials during the tens of

  16. Practical high efficiency bifacial solar cells

    SciTech Connect

    Moehlecke, A.; Zanesco, I.; Luque, A.

    1994-12-31

    In this paper, the authors present a practical process to obtain bifacial solar cells. These cells are made using p{sup +}nn{sup +} structure on high-medium base resistivity, continuous emitters and with a process that maintains high bulk minority carrier lifetime. Efficiencies of 19.1% and 18.1% are achieved under standard conditions when the cell is illuminated by n{sup +}n high-low junction and when it is illuminated by P{sup +}n junction, respectively. The authors remark that the n{sup +}n high-low junction provides a higher current density and a good ratio between generated current of each face is found to be of about 103%.

  17. 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.

  18. Responses of high-elevation herbaceous plant assemblages to low glacial CO₂ concentrations revealed by fossil marmot (Marmota) teeth.

    PubMed

    McLean, Bryan S; Ward, Joy K; Polito, Michael J; Emslie, Steven D

    2014-08-01

    Atmospheric CO2 cycles of the Quaternary likely imposed major constraints on the physiology and growth of C3 plants worldwide. However, the measured record of this remains both geographically and taxonomically sparse. We present the first reconstruction of physiological responses in a late Quaternary high-elevation herbaceous plant community from the Southern Rocky Mountains, USA. We used a novel proxy-fossilized tooth enamel of yellow-bellied marmots (Marmota flaviventris)-which we developed using detailed isotopic analysis of modern individuals. Calculated C isotopic discrimination (Δ) of alpine plants was nearly 2 ‰ lower prior to the Last Glacial Maximum than at present, a response almost identical to that of nonherbaceous taxa from lower elevations. However, initial shifts in Δ aligned most closely with the onset of the late Pleistocene bipolar temperature "seesaw" rather than CO2 increase, indicating unique limitations on glacial-age high-elevation plants may have existed due to both low temperatures and low CO2. Further development of system-specific faunal proxies can help to clarify this and other plant- and ecosystem-level responses to past environmental change.

  19. HIGH-EFFICIENCY AUTONOMOUS LASER ADAPTIVE OPTICS

    SciTech Connect

    Baranec, Christoph; Riddle, Reed; Tendulkar, Shriharsh; Hogstrom, Kristina; Bui, Khanh; Dekany, Richard; Kulkarni, Shrinivas; Law, Nicholas M.; Ramaprakash, A. N.; Burse, Mahesh; Chordia, Pravin; Das, Hillol; Punnadi, Sujit

    2014-07-20

    As new large-scale astronomical surveys greatly increase the number of objects targeted and discoveries made, the requirement for efficient follow-up observations is crucial. Adaptive optics imaging, which compensates for the image-blurring effects of Earth's turbulent atmosphere, is essential for these surveys, but the scarcity, complexity and high demand of current systems limit their availability for following up large numbers of targets. To address this need, we have engineered and implemented Robo-AO, a fully autonomous laser adaptive optics and imaging system that routinely images over 200 objects per night with an acuity 10 times sharper at visible wavelengths than typically possible from the ground. By greatly improving the angular resolution, sensitivity, and efficiency of 1-3 m class telescopes, we have eliminated a major obstacle in the follow-up of the discoveries from current and future large astronomical surveys.

  20. High-efficiency Autonomous Laser Adaptive Optics

    NASA Astrophysics Data System (ADS)

    Baranec, Christoph; Riddle, Reed; Law, Nicholas M.; Ramaprakash, A. N.; Tendulkar, Shriharsh; Hogstrom, Kristina; Bui, Khanh; Burse, Mahesh; Chordia, Pravin; Das, Hillol; Dekany, Richard; Kulkarni, Shrinivas; Punnadi, Sujit

    2014-07-01

    As new large-scale astronomical surveys greatly increase the number of objects targeted and discoveries made, the requirement for efficient follow-up observations is crucial. Adaptive optics imaging, which compensates for the image-blurring effects of Earth's turbulent atmosphere, is essential for these surveys, but the scarcity, complexity and high demand of current systems limit their availability for following up large numbers of targets. To address this need, we have engineered and implemented Robo-AO, a fully autonomous laser adaptive optics and imaging system that routinely images over 200 objects per night with an acuity 10 times sharper at visible wavelengths than typically possible from the ground. By greatly improving the angular resolution, sensitivity, and efficiency of 1-3 m class telescopes, we have eliminated a major obstacle in the follow-up of the discoveries from current and future large astronomical surveys.

  1. Highly efficient Raman distributed feedback fibre lasers.

    PubMed

    Shi, Jindan; Alam, Shaif-ul; Ibsen, Morten

    2012-02-27

    We demonstrate highly efficient Raman distributed feedback (DFB) fibre lasers for the first time with up to 1.6 W of continuous wave (CW) output power. The DFB Bragg gratings are written directly into two types of commercially available passive germano-silica fibres. Two lasers of 30 cm length are pumped with up to 15 W of CW power at 1068 nm. The threshold power is ~2 W for a Raman-DFB (R-DFB) laser written in standard low-NA fibre, and only ~1 W for a laser written in a high-NA fibre, both of which oscillate in a narrow linewidth of <0.01 nm at ~1117 nm and ~1109 nm, respectively. The slope efficiencies are ~74% and ~93% with respect to absorbed pump power in the low-NA fibre and high-NA fibre respectively. Such high conversion efficiency suggests that very little energy is lost in the form of heat through inefficient energy transfer. Our results are supported by numerical simulations, and furthermore open up for the possibility of having narrow linewidth all-fibre laser sources in wavelength bands not traditionally covered by rare-earth doped silica fibres. Simulations also imply that this technology has the potential to produce even shorter R-DFB laser devices at the centimetre-level and with mW-level thresholds, if Bragg gratings formed in fibre materials with higher intrinsic Raman gain coefficient than silica are used. These materials include for example tellurite or chalcogenide glasses. Using glasses like these would also open up the possibility of having narrow linewidth fibre sources with DFB laser oscillating much further into the IR than what currently is possible with rare-earth doped silica glasses.

  2. Fossil Cores In The Kepler Data

    NASA Astrophysics Data System (ADS)

    Jackson, Brian

    Most gas giant exoplanets with orbital periods < few days are unstable against tidal decay and may be tidally disrupted before their host stars leave the main sequence. These gas giants probably contain rocky/icy cores, and so their cores will be stranded near their progenitor's Roche limit (few hours orbital period). These fossil cores will evade the Kepler mission's transit search because it is focused on periods > 0.5 days, but finding these fossil cores would provide unprecedented insights into planetary interiors and formation ? e.g., they would be a smoking gun favoring formation of gas giants via core accretion. We propose to search for and characterize fossil cores in the Kepler dataset. We will vet candidates using the Kepler photometry and auxiliary data, collect ground-based spectra of the host stars and radial-velocity (RV) and adaptive optics (AO) data to corroborate candidates. We will also constrain stellar tidal dissipation efficiencies (parameterized by Q) by determining our survey's completeness, elucidating dynamical origins and evolution of exoplanets even if we find no fossil cores. Our preliminary search has already found several dozen candidates, so the proposed survey has a high likelihood of success.

  3. Sustainability of Fossil Fuels

    NASA Astrophysics Data System (ADS)

    Lackner, K. S.

    2002-05-01

    For a sustainable world economy, energy is a bottleneck. Energy is at the basis of a modern, technological society, but unlike materials it cannot be recycled. Energy or more precisely "negentropy" (the opposite of entropy) is always consumed. Thus, one either accepts the use of large but finite resources or must stay within the limits imposed by dilute but self-renewing resources like sunlight. The challenge of sustainable energy is exacerbated by likely growth in world energy demand due to increased population and increased wealth. Most of the world still has to undergo the transition to a wealthy, stable society with the near zero population growth that characterizes a modern industrial society. This represents a huge unmet demand. If ten billion people were to consume energy like North Americans do today, world energy demand would be ten times higher. In addition, technological advances while often improving energy efficiency tend to raise energy demand by offering more opportunity for consumption. Energy consumption still increases at close to the 2.3% per year that would lead to a tenfold increase over the course of the next century. Meeting future energy demands while phasing out fossil fuels appears extremely difficult. Instead, the world needs sustainable or nearly sustainable fossil fuels. I propose the following definition of sustainable under which fossil fuels would well qualify: The use of a technology or resource is sustainable if the intended and unintended consequences will not force its abandonment within a reasonable planning horizon. Of course sustainable technologies must not be limited by resource depletion but this is only one of many concerns. Environmental impacts, excessive land use, and other constraints can equally limit the use of a technology and thus render it unsustainable. In the foreseeable future, fossil fuels are not limited by resource depletion. However, environmental concerns based on climate change and other environmental

  4. High Quantum Efficiency OLED Lighting Systems

    SciTech Connect

    Shiang, Joseph

    2011-09-30

    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 process 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.

  5. Efficient High Pressure MixtureState Equations

    NASA Technical Reports Server (NTRS)

    Harstad, K. G.; Miller, R. S.; Bellan, J.

    1996-01-01

    A method is presented for an accurate noniterative, computationally efficient calculation of high pressure fluid mixture equations of state, especially targeted to gas turbines and rocket engines. Pressures above 1 bar and temperatures above 100 K are addressed. The method is based on curve fitting an effective reference state relative to departure funcitons formed using the Peng-Robinson cubic state equation. Fit parameters for H(sub 2), O(sub 2), N(sub 2), propane, n-heptane and methanol are given.

  6. Highly Efficient Prion Transmission by Blood Transfusion

    PubMed Central

    Andréoletti, Olivier; Litaise, Claire; Simmons, Hugh; Corbière, Fabien; Lugan, Séverine; Costes, Pierrette; Schelcher, François; Vilette, Didier; Grassi, Jacques; Lacroux, Caroline

    2012-01-01

    It is now clearly established that the transfusion of blood from variant CJD (v-CJD) infected individuals can transmit the disease. Since the number of asymptomatic infected donors remains unresolved, inter-individual v-CJD transmission through blood and blood derived products is a major public health concern. Current risk assessments for transmission of v-CJD by blood and blood derived products by transfusion rely on infectious titers measured in rodent models of Transmissible Spongiform Encephalopathies (TSE) using intra-cerebral (IC) inoculation of blood components. To address the biological relevance of this approach, we compared the efficiency of TSE transmission by blood and blood components when administrated either through transfusion in sheep or by intra-cerebral inoculation (IC) in transgenic mice (tg338) over-expressing ovine PrP. Transfusion of 200 µL of blood from asymptomatic infected donor sheep transmitted prion disease with 100% efficiency thereby displaying greater virulence than the transfusion of 200 mL of normal blood spiked with brain homogenate material containing 103ID50 as measured by intracerebral inoculation of tg338 mice (ID50 IC in tg338). This was consistent with a whole blood titer greater than 103.6 ID50 IC in tg338 per mL. However, when the same blood samples were assayed by IC inoculation into tg338 the infectious titers were less than 32 ID per mL. Whereas the transfusion of crude plasma to sheep transmitted the disease with limited efficacy, White Blood Cells (WBC) displayed a similar ability to whole blood to infect recipients. Strikingly, fixation of WBC with paraformaldehyde did not affect the infectivity titer as measured in tg338 but dramatically impaired disease transmission by transfusion in sheep. These results demonstrate that TSE transmission by blood transfusion can be highly efficient and that this efficiency is more dependent on the viability of transfused cells than the level of infectivity measured by IC

  7. Development of Metal Oxide Nanostructure-based Optical Sensors for Fossil Fuel Derived Gases Measurement at High Temperature

    SciTech Connect

    Chen, Kevin P.

    2015-02-13

    operation temperature up to 750°C, first distributed chemical measurements at the record high temperature up to 700°C, first distributed pressure measurement at the record high temperature up to 800°C, and the fiber laser sensors with the record high operation temperature up to 700°C. The research performed by this program dramatically expand the functionality, adaptability, and applicability of distributed fiber optical sensors with potential applications in a number of high-temperature energy systems such as fossil-fuel power generation, high-temperature fuel cell applications, and potential for nuclear energy systems.

  8. Vacuum MOCVD fabrication of high efficience cells

    NASA Technical Reports Server (NTRS)

    Partain, L. D.; Fraas, L. M.; Mcleod, P. S.; Cape, J. A.

    1985-01-01

    Vacuum metal-organic-chemical-vapor-deposition (MOCVD) is a new fabrication process with improved safety and easier scalability due to its metal rather than glass construction and its uniform multiport gas injection system. It uses source materials more efficiently than other methods because the vacuum molecular flow conditions allow the high sticking coefficient reactants to reach the substrates as undeflected molecular beams and the hot chamber walls cause the low sticking coefficient reactants to bounce off the walls and interact with the substrates many times. This high source utilization reduces the materials costs power device and substantially decreases the amounts of toxic materials that must be handled as process effluents. The molecular beams allow precise growth control. With improved source purifications, vacuum MOCVD has provided p GaAs layers with 10-micron minority carrier diffusion lengths and GaAs and GaAsSb solar cells with 20% AMO efficiencies at 59X and 99X sunlight concentration ratios. Mechanical stacking has been identified as the quickest, most direct and logical path to stacked multiple-junction solar cells that perform better than the best single-junction devices. The mechanical stack is configured for immediate use in solar arrays and allows interconnections that improve the system end-of-life performance in space.

  9. 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.

  10. High Efficiency Targets for High Gain Inertial Confinement Fusion.

    DTIC Science & Technology

    1986-09-19

    Inertial Confinement Fusion JOHN H. GARDNER AND STEPHEN E. BODNER Laboratory for Computational Physics DTIC CD ELECTEf OCT 241986 j NU Aproedfr...81425 " 11 TITLE (include Security Classification) High Efficiency Targets for High Gain Inertial Confinement Fusion 12. PERSONAL AUTHOR(S) Gardner, John ...ArearCod) 22c OFFICE SYMBOL % John H. Gardner (202) 767-3055 Code 4040 DO FORM 1473. 84 MAR 83 APR edtion may be used until exhausted SECURITY

  11. High Efficiency, Illumination Quality OLEDs for Lighting

    SciTech Connect

    Joseph Shiang; James Cella; Kelly Chichak; Anil Duggal; Kevin Janora; Chris Heller; Gautam Parthasarathy; Jeffery Youmans; Joseph Shiang

    2008-03-31

    The goal of the program was to demonstrate a 45 lumen per watt white light device based upon the use of multiple emission colors through the use of solution processing. This performance level is a dramatic extension of the team's previous 15 LPW large area illumination device. The fundamental material system was based upon commercial polymer materials. The team was largely able to achieve these goals, and was able to deliver to DOE a 90 lumen illumination source that had an average performance of 34 LPW a 1000 cd/m{sup 2} with peak performances near 40LPW. The average color temperature is 3200K and the calculated CRI 85. The device operated at a brightness of approximately 1000cd/m{sup 2}. The use of multiple emission colors particularly red and blue, provided additional degrees of design flexibility in achieving white light, but also required the use of a multilayered structure to separate the different recombination zones and prevent interconversion of blue emission to red emission. The use of commercial materials had the advantage that improvements by the chemical manufacturers in charge transport efficiency, operating life and material purity could be rapidly incorporated without the expenditure of additional effort. The program was designed to take maximum advantage of the known characteristics of these material and proceeded in seven steps. (1) Identify the most promising materials, (2) assemble them into multi-layer structures to control excitation and transport within the OLED, (3) identify materials development needs that would optimize performance within multilayer structures, (4) build a prototype that demonstrates the potential entitlement of the novel multilayer OLED architecture (5) integrate all of the developments to find the single best materials set to implement the novel multilayer architecture, (6) further optimize the best materials set, (7) make a large area high illumination quality white OLED. A photo of the final deliverable is shown. In

  12. 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

  13. Highly efficient polarization control using subwavelength high contrast transmitarrays

    NASA Astrophysics Data System (ADS)

    Arbabi, Amir; Horie, Yu; Bagheri, Mahmood; Faraon, Andrei

    2015-02-01

    We report efficient wave plates with different retardations and orientations of fast axes realized using transmitarrays composed of a periodic arrangement of amorphous silicon elliptical cylinders on glass. We show that novel polarization devices which locally rotate the polarization by different angles while preserving the wavefront can be demonstrated using such a high contrast transmitarray. We present design, fabrication and experimental characterization results for near infrared transmissive wave retarders with efficiencies in excess of 90%, and discuss the potential applications of atwill local polarization control enabled by this technology.

  14. Novel Nanophosphors for High Efficiency Fluorescent Lamps

    SciTech Connect

    Alok Srivatava

    2007-03-31

    This is the Final Report of the Novel Nanophosphors for High Efficiency Fluorescent Lamps, Department of Energy (DOE). The overall goal of this three-year program is to develop novel hybrid phosphors by coating commercially available lamp phosphors with highly stable wide band-gap nanocrystalline phosphors (NCP). The prime technical approach is the development of NCP quantum-splitting phosphor (QSP) and ultra-violet (UV) emitting phosphors with quantum efficiencies exceeding that of the conventional phosphors at 185 nm. The novel hybrid phosphors will increase the efficiency of the fluorescent lamps by up to 32%, enabling total energy savings of 0.26 quads, the reduction in the U.S. energy bill by $6.5 billion and the reduction of the annual carbon emission by 4.1 billion kilogram. Our work started by investigating through modeling calculations the requirement for the particle size of the NCP. Our work to develop suitable nanocrystalline phosphors started with the known oxide quantum splitting and UV emitting phosphors. We demonstrated several synthesis techniques for the production of high quality nanocrystalline materials that crystallizes in the desired phase and with the desired particle size. In collaboration with our subcontractor we demonstrated the feasibility for the manufacture of NC phosphors. We also demonstrated novel techniques of coating the NCP on the surface of micron sized phosphors. Our chief achievement pertains to the successful testing of the coated hybrid phosphor systems in linear fluorescent lamps. In linear fluorescent lamp tests, we have demonstrated up to 7% increase in the efficacy of hybrid phosphors over the conventional (uncoated) phosphors. We have also demonstrated the improvement in the lumen maintenance of the coated phosphors. A hybrid phosphor system based on the commercial red emitting phosphor, Y{sub 2}O{sub 3}:Eu{sup 3+} did not show the anticipated improvement in lamp efficacy. We explored the reasons for this observation

  15. Efficient Compression of High Resolution Climate Data

    NASA Astrophysics Data System (ADS)

    Yin, J.; Schuchardt, K. L.

    2011-12-01

    resolution climate data can be massive. Those data can consume a huge amount of disk space for storage, incur significant overhead for outputting data during simulation, introduce high latency for visualization and analysis, and may even make interactive visualization and analysis impossible given the limit of the data that a conventional cluster can handle. These problems can be alleviated by with effective and efficient data compression techniques. Even though HDF5 format supports compression, previous work has mainly focused on employ traditional general purpose compression schemes such as dictionary coder and block sorting based compression scheme. Those compression schemes mainly focus on encoding repeated byte sequences efficiently and are not well suitable for compressing climate data consist mainly of distinguished float point numbers. We plan to select and customize our compression schemes according to the characteristics of high-resolution climate data. One observation on high resolution climate data is that as the resolution become higher, values of various climate variables such as temperature and pressure, become closer in nearby cells. This provides excellent opportunities for predication-based compression schemes. We have performed a preliminary estimation of compression ratios of a very simple minded predication-based compression ratio in which we compute the difference between current float point number with previous float point number and then encoding the exponent and significance part of the float point number with entropy-based compression scheme. Our results show that we can achieve higher compression ratios between 2 and 3 in lossless compression, which is significantly higher than traditional compression algorithms. We have also developed lossy compression with our techniques. We can achive orders of magnitude data reduction while ensure error bounds. Moreover, our compression scheme is much more efficient and introduces much less overhead

  16. Garnet-bearing ultramafic rocks from the Dominican Republic: Fossil mantle plume fragments in an ultra high pressure oceanic complex?

    NASA Astrophysics Data System (ADS)

    Gazel, Esteban; Abbott, Richard N.; Draper, Grenville

    2011-07-01

    Ultra high pressure (UHP) garnet-bearing ultramafic rocks from the Dominican Republic may represent the only known example where such rocks were exhumed at an ocean-ocean convergent plate boundary, and where the protolith crystallized from a UHP magma (> 3.2 GPa, > 1500 °C). This study focuses on the petrology and geochemistry of one of the ultramafic lithologies, the pegmatitic garnet-clinopyroxenite (garnet + clinopyroxene + spinel + corundum + hornblende). Three distinct types of garnet were recognized: Type-1 garnet (low Ca, high Mg) is interpreted as near magmatic (P > 3.2 GPa, > 1500 °C). Type-1‧ garnet (high Ca, low Mg) is interpreted as having formed approximately isochemically from magmatic high-Al clinopyroxene. Type-2 garnet (intermediate Ca, high Mg, and low Fe + Mn) formed together with hornblende as a result of late, low-pressure retrograde hydration. Clinopyroxene is close to diopside-hedenbergite (Mg# ~ 88) and metasomatized by arc-related fluids. Spinel and corundum occur as microinclusions in type-1 and type-1‧ garnets in the only reported natural occurrence of coexisting garnet + spinel + corundum, indicative of very high pressure. Chondrite-normalized REEs (rare earth elements) of the garnets show humped or weakly sinusoidal patterns, typically associated with garnet inclusions in diamond and garnet in kimberlite that crystallized at UHP conditions. These humped to weakly sinusoidal REE patterns developed as the result of interaction with a light REE-enriched metasomatic fluid. Partitioning of REEs between type-1‧ and type-1 garnets is consistent with the former having inherited its REEs from a high-Al clinopyroxene predecessor. The partitioning preserves a record of near-solidus temperatures (~ 1475 °C). Petrology and phase relationships independently suggest near-solidus conditions > 1500 °C (the highest temperature conditions reported in a UHP orogenic setting), providing evidence for an origin in a mantle plume. Therefore, the

  17. Tips for selecting highly efficient cyclones

    SciTech Connect

    Amrein, D.L.

    1995-05-01

    Cyclone dust collectors have been used--and misused--all over the world for more than 100 years. One reason for the misuse is a common perception among users that all cyclones are created equal--that is, as long as a cyclone resembles a cylinder with an attached cone, it will do its job. However, to maximize separation efficiency in a specific application requires a precise cyclone design, engineered to exact fit many possible variables. A well-designed cyclone, for instance, can achieve efficiencies as high s 99.9+% when operated properly within the envelope of its specifications. Nonetheless, cyclones are often used only as first-stage filters for performing crude separations, with final collections being carried out by more-costly baghouses and scrubbers. Compared with baghouses and scrubbers, cyclones have two important considerations in their favor. One, they are almost invariably safer--in terms of the potential for generating fires and explosions--than fabric filters. Second, cyclones have lower maintenance costs since there are no filter media to replace. The paper discusses the operation, design, and troubleshooting of cyclones.

  18. Highly Efficient Vector-Inversion Pulse Generators

    NASA Technical Reports Server (NTRS)

    Rose, Franklin

    2004-01-01

    Improved transmission-line pulse generators of the vector-inversion type are being developed as lightweight sources of pulsed high voltage for diverse applications, including spacecraft thrusters, portable x-ray imaging systems, impulse radar systems, and corona-discharge systems for sterilizing gases. In this development, more than the customary attention is paid to principles of operation and details of construction so as to the maximize the efficiency of the pulse-generation process while minimizing the sizes of components. An important element of this approach is segmenting a pulse generator in such a manner that the electric field in each segment is always below the threshold for electrical breakdown. One design of particular interest, a complete description of which was not available at the time of writing this article, involves two parallel-plate transmission lines that are wound on a mandrel, share a common conductor, and are switched in such a manner that the pulse generator is divided into a "fast" and a "slow" section. A major innovation in this design is the addition of ferrite to the "slow" section to reduce the size of the mandrel needed for a given efficiency.

  19. High efficiency Brayton cycles using LNG

    DOEpatents

    Morrow, Charles W.

    2006-04-18

    A modified, closed-loop Brayton cycle power conversion system that uses liquefied natural gas as the cold heat sink media. When combined with a helium gas cooled nuclear reactor, achievable efficiency can approach 68 76% (as compared to 35% for conventional steam cycle power cooled by air or water). A superheater heat exchanger can be used to exchange heat from a side-stream of hot helium gas split-off from the primary helium coolant loop to post-heat vaporized natural gas exiting from low and high-pressure coolers. The superheater raises the exit temperature of the natural gas to close to room temperature, which makes the gas more attractive to sell on the open market. An additional benefit is significantly reduced costs of a LNG revaporization plant, since the nuclear reactor provides the heat for vaporization instead of burning a portion of the LNG to provide the heat.

  20. High efficiency porphyrin sensitized mesoscopic solar cells

    NASA Astrophysics Data System (ADS)

    Giordano, Fabrizio; Yi, Chenyi; Teuscher, Joël.; Zakeeruddin, Shaik M.; Grätzel, Michael

    2014-10-01

    Dye-Sensitized Solar Cells (DSSC) represents a reliable technology, ready for the market and able to compete with silicon solar cells for specific fields of application. Porphyrin dyes allow reaching high power conversion efficiency in conjunction with cobalt redox electrolytes due to larger open circuit potentials. The bigger size of the cobalt complexes compared to standard iodide/triiodide redox couple hampers its percolation through the meso-porous TiO2 network, thus impairing the regeneration process. In case of porphyrin dyes mass transport problems in the electrolyte need to be carefully handled, due to the large size of the sensitizing molecule and the bulky cobalt complexes. Herein we report the study of structural variations on porphyrin sensitizers and their influence on the DSSC performance with cobalt based redox electrolyte.

  1. 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

  2. A High-Efficiency Superhydrophobic Plasma Separator

    PubMed Central

    Liu, Changchun; Liao, Shih-Chuan; Song, Jinzhao; Mauk, Michael G.; Li, Xuanwen; Wu, Gaoxiang; Ge, Dengteng; Greenberg, Robert M.; Yang, Shu; Bau, Haim H.

    2016-01-01

    To meet stringent limit-of-detection specifications for low abundance target molecules, a relatively large volume of plasma is needed for many blood-based clinical diagnostics. Conventional centrifugation methods for plasma separation are not suitable for on-site testing or bedside diagnostics. Here, we report a simple, yet high-efficiency, clamshell-style, superhydrophobic plasma separator that is capable of separating a relatively large volume of plasma from several hundred microliters of whole blood (finger-prick blood volume). The plasma separator consists of a superhydrophobic top cover with a separation membrane and a superhydrophobic bottom substrate. Unlike previously reported membrane-based plasma separators, the separation membrane in our device is positioned at the top of the sandwiched whole blood film to increase the membrane separation capacity and plasma yield. In addition, the device’s superhydrophobic characteristics (i) facilitates the formation of well-defined, contracted, thin blood film with a high contact angle; (ii) minimizes biomolecular adhesion to surfaces; (iii) increases blood clotting time; and (iv) reduces blood cell hemolysis. The device demonstrated a “blood in-plasma out” capability, consistently extracting 65±21.5 μL of plasma from 200 μL of whole blood in less than 10 min without electrical power. The device was used to separate plasma from Schistosoma mansoni genomic DNA-spiked whole blood with a recovery efficiency of > 84.5 ± 25.8 %. The S. mansoni genomic DNA in the separated plasma was successfully tested on our custom-made microfluidic chip by using loop mediated isothermal amplification (LAMP) method. PMID:26732765

  3. Novel High Efficient Organic Photovoltaic Materials

    NASA Technical Reports Server (NTRS)

    Sun, Sam; Haliburton, James; Wang, Yi-Qing; Fan, Zhen; Taft, Charles; Maaref, Shahin; Bailey, Sheila (Technical Monitor)

    2003-01-01

    Solar energy is a renewable, nonpolluting, and most abundant energy source for human exploration of a remote site or outer space. In order to generate appreciable electrical power in space or on the earth, it is necessary to collect sunlight from large areas and with high efficiency due to the low density of sunlight. Future organic or polymer (plastic) solar cells appear very attractive due to their unique features such as light weight, flexible shape, tunability of energy band-gaps via versatile molecular or supramolecular design, synthesis, processing and device fabrication schemes, and much lower cost on large scale industrial production. It has been predicted that supramolecular and nano-phase separated block copolymer systems containing electron rich donor blocks and electron deficient acceptor blocks may facilitate the charge carrier separation and migration due to improved electronic ultrastructure and morphology in comparison to polymer composite system. This presentation will describe our recent progress in the design, synthesis and characterization of a novel block copolymer system containing donor and acceptor blocks covalently attached. Specifically, the donor block contains an electron donating alkyloxy derivatized polyphenylenevinylene (RO-PPV), the acceptor block contains an electron withdrawing alkyl-sulfone derivatized polyphenylenevinylene (SF-PPV). The key synthetic strategy includes the synthesis of each individual block first, then couple the blocks together. While the donor block has a strong PL emission at around 560 nm, and acceptor block has a strong PL emission at around 520 nm, the PL emissions of final block copolymers are severely quenched. This verifies the expected electron transfer and charge separation due to interfaces of donor and acceptor nano phase separated blocks. The system therefore has potential for variety light harvesting applications, including high efficient photovoltaic applications.

  4. A high-efficiency superhydrophobic plasma separator.

    PubMed

    Liu, Changchun; Liao, Shih-Chuan; Song, Jinzhao; Mauk, Michael G; Li, Xuanwen; Wu, Gaoxiang; Ge, Dengteng; Greenberg, Robert M; Yang, Shu; Bau, Haim H

    2016-02-07

    To meet stringent limit-of-detection specifications for low abundance target molecules, a relatively large volume of plasma is needed for many blood-based clinical diagnostics. Conventional centrifugation methods for plasma separation are not suitable for on-site testing or bedside diagnostics. Here, we report a simple, yet high-efficiency, clamshell-style, superhydrophobic plasma separator that is capable of separating a relatively large volume of plasma from several hundred microliters of whole blood (finger-prick blood volume). The plasma separator consists of a superhydrophobic top cover with a separation membrane and a superhydrophobic bottom substrate. Unlike previously reported membrane-based plasma separators, the separation membrane in our device is positioned at the top of the sandwiched whole blood film to increase the membrane separation capacity and plasma yield. In addition, the device's superhydrophobic characteristics (i) facilitates the formation of well-defined, contracted, thin blood film with a high contact angle; (ii) minimizes biomolecular adhesion to surfaces; (iii) increases blood clotting time; and (iv) reduces blood cell hemolysis. The device demonstrated a "blood in-plasma out" capability, consistently extracting 65 ± 21.5 μL of plasma from 200 μL of whole blood in less than 10 min without electrical power. The device was used to separate plasma from Schistosoma mansoni genomic DNA-spiked whole blood with a recovery efficiency of >84.5 ± 25.8%. The S. mansoni genomic DNA in the separated plasma was successfully tested on our custom-made microfluidic chip by using loop mediated isothermal amplification (LAMP) method.

  5. Fossilization of melanosomes via sulfurization.

    PubMed

    McNamara, Maria E; van Dongen, Bart E; Lockyer, Nick P; Bull, Ian D; Orr, Patrick J

    2016-05-01

    Fossil melanin granules (melanosomes) are an important resource for inferring the evolutionary history of colour and its functions in animals. The taphonomy of melanin and melanosomes, however, is incompletely understood. In particular, the chemical processes responsible for melanosome preservation have not been investigated. As a result, the origins of sulfur-bearing compounds in fossil melanosomes are difficult to resolve. This has implications for interpretations of original colour in fossils based on potential sulfur-rich phaeomelanosomes. Here we use pyrolysis gas chromatography mass spectrometry (Py-GCMS), fourier transform infrared spectroscopy (FTIR) and time of flight secondary ion mass spectrometry (ToF-SIMS) to assess the mode of preservation of fossil microstructures, confirmed as melanosomes based on the presence of melanin, preserved in frogs from the Late Miocene Libros biota (NE Spain). Our results reveal a high abundance of organosulfur compounds and non-sulfurized fatty acid methyl esters in both the fossil tissues and host sediment; chemical signatures in the fossil tissues are inconsistent with preservation of phaeomelanin. Our results reflect preservation via the diagenetic incorporation of sulfur, i.e. sulfurization (natural vulcanization), and other polymerization processes. Organosulfur compounds and/or elevated concentrations of sulfur have been reported from melanosomes preserved in various invertebrate and vertebrate fossils and depositional settings, suggesting that preservation through sulfurization is likely to be widespread. Future studies of sulfur-rich fossil melanosomes require that the geochemistry of the host sediment is tested for evidence of sulfurization in order to constrain interpretations of potential phaeomelanosomes and thus of original integumentary colour in fossils.

  6. The penalty of a long, hot summer. Photosynthetic acclimation to high CO2 and continuous light in "living fossil" conifers.

    PubMed

    Osborne, Colin P; Beerling, David J

    2003-10-01

    Deciduous forests covered the ice-free polar regions 280 to 40 million years ago under warm "greenhouse" climates and high atmospheric pCO2. Their deciduous habit is frequently interpreted as an adaptation for minimizing carbon losses during winter, but experiments with "living fossils" in a simulated warm polar environment refute this explanation. Measured carbon losses through leaf abscission of deciduous trees are significantly greater than losses through winter respiration in evergreens, yet annual rates of primary productivity are similar in all species. Here, we investigate mechanisms underlying this apparent paradox by measuring the seasonal patterns of leaf photosynthesis (A) under pCO2 enrichment in the same trees. During spring, A increased significantly in coastal redwood (Sequoia sempervirens), dawn redwood (Metasequoia glyptostroboides), and swamp cypress (Taxodium distichum) at an elevated pCO2 of 80 Pa compared with controls at 40 Pa. However, strong acclimation in Rubisco carboxylation capacity (Vc,max) completely offset the CO2 response of A in all species by the end of 6 weeks of continuous illumination in the simulated polar summer. Further measurements demonstrated the temporary nature of acclimation, with increases in Vc,max during autumn restoring the CO2 sensitivity of A. Contrary to expectations, the acclimation of Vc,max was not always accompanied by accumulation of leaf carbohydrates, but was associated with a decline in leaf nitrogen in summer, suggesting an alteration of the balance in plant sources and sinks for carbon and nitrogen. Preliminary calculations using A indicated that winter carbon losses through deciduous leaf abscission and respiration were recovered by 10 to 25 d of canopy carbon fixation during summer, thereby explaining the productivity paradox.

  7. White LED with High Package Extraction Efficiency

    SciTech Connect

    Yi Zheng; Matthew Stough

    2008-09-30

    The goal of this project is to develop a high efficiency phosphor converting (white) Light Emitting Diode (pcLED) 1-Watt package through an increase in package extraction efficiency. A transparent/translucent monolithic phosphor is proposed to replace the powdered phosphor to reduce the scattering caused by phosphor particles. Additionally, a multi-layer thin film selectively reflecting filter is proposed between blue LED die and phosphor layer to recover inward yellow emission. At the end of the project we expect to recycle approximately 50% of the unrecovered backward light in current package construction, and develop a pcLED device with 80 lm/W{sub e} using our technology improvements and commercially available chip/package source. The success of the project will benefit luminous efficacy of white LEDs by increasing package extraction efficiency. In most phosphor-converting white LEDs, the white color is obtained by combining a blue LED die (or chip) with a powdered phosphor layer. The phosphor partially absorbs the blue light from the LED die and converts it into a broad green-yellow emission. The mixture of the transmitted blue light and green-yellow light emerging gives white light. There are two major drawbacks for current pcLEDs in terms of package extraction efficiency. The first is light scattering caused by phosphor particles. When the blue photons from the chip strike the phosphor particles, some blue light will be scattered by phosphor particles. Converted yellow emission photons are also scattered. A portion of scattered light is in the backward direction toward the die. The amount of this backward light varies and depends in part on the particle size of phosphors. The other drawback is that yellow emission from phosphor powders is isotropic. Although some backward light can be recovered by the reflector in current LED packages, there is still a portion of backward light that will be absorbed inside the package and further converted to heat. Heat

  8. Introducing Evolution to Non-Biology Majors via the Fossil Record: A Case Study from the Israeli High School System.

    ERIC Educational Resources Information Center

    Dodick, Jeff; Orion, Nir

    2003-01-01

    Discusses challenges faced in the teaching and learning of evolution. Presents a curricular program and a case study on evolutionary biology. Investigates students' conceptual knowledge after exposure to the program "From Dinosaurs to Darwin," which focuses on fossil records as evidence of evolution. (Contains 32 references.) (YDS)

  9. Novel Modified Optical Fibers for High Temperature In-Situ Miniaturized Gas Sensors in Advanced Fossil Energy Systems

    SciTech Connect

    Pickrell, Gary; Scott, Brian

    2014-06-30

    This report covers the technical progress on the program “Novel Modified Optical Fibers for High Temperature In-Situ Miniaturized Gas Sensors in Advanced Fossil Energy Systems”, funded by the National Energy Technology Laboratory of the U.S. Department of Energy, and performed by the Materials Science & Engineering and Electrical & Computer Engineering Departments at Virginia Tech, and summarizes technical progress from July 1st, 2005 –June 30th, 2014. The objective of this program was to develop novel fiber materials for high temperature gas sensors based on evanescent wave absorption in optical fibers. This project focused on two primary areas: the study of a sapphire photonic crystal fiber (SPCF) for operation at high temperature and long wavelengths, and a porous glass based fiber optic sensor for gas detection. The sapphire component of the project focused on the development of a sapphire photonic crystal fiber, modeling of the new structures, fabrication of the optimal structure, development of a long wavelength interrogation system, testing of the optical properties, and gas and temperature testing of the final sensor. The fabrication of the 6 rod SPCF gap bundle (diameter of 70μm) with a hollow core was successfully constructed with lead-in and lead-out 50μm diameter fiber along with transmission and gas detection testing. Testing of the sapphire photonic crystal fiber sensor capabilities with the developed long wavelength optical system showed the ability to detect CO2 at or below 1000ppm at temperatures up to 1000°C. Work on the porous glass sensor focused on the development of a porous clad solid core optical fiber, a hollow core waveguide, gas detection capabilities at room and high temperature, simultaneous gas species detection, suitable joining technologies for the lead-in and lead-out fibers and the porous sensor, sensor system sensitivity improvement, signal processing improvement, relationship between pore structure and fiber

  10. Tailored Materials for High Efficiency CIDI Engines

    SciTech Connect

    Grant, G.J.; Jana, S.

    2012-03-30

    The overall goal of the project, Tailored Materials for High Efficiency Compression Ignition Direct Injection (CIDI) Engines, is to enable the implementation of new combustion strategies, such as homogeneous charge compression ignition (HCCI), that have the potential to significantly increase the energy efficiency of current diesel engines and decrease fuel consumption and environmental emissions. These strategies, however, are increasing the demands on conventional engine materials, either from increases in peak cylinder pressure (PCP) or from increases in the temperature of operation. The specific objective of this project is to investigate the application of a new material processing technology, friction stir processing (FSP), to improve the thermal and mechanical properties of engine components. The concept is to modify the surfaces of conventional, low-cost engine materials. The project focused primarily on FSP in aluminum materials that are compositional analogs to the typical piston and head alloys seen in small- to mid-sized CIDI engines. Investigations have been primarily of two types over the duration of this project: (1) FSP of a cast hypoeutectic Al-Si-Mg (A356/357) alloy with no introduction of any new components, and (2) FSP of Al-Cu-Ni alloys (Alloy 339) by physically stirring-in various quantities of carbon nanotubes/nanofibers or carbon fibers. Experimental work to date on aluminum systems has shown significant increases in fatigue lifetime and stress-level performance in aluminum-silicon alloys using friction processing alone, but work to demonstrate the addition of carbon nanotubes and fibers into aluminum substrates has shown mixed results due primarily to the difficulty in achieving porosity-free, homogeneous distributions of the particulate. A limited effort to understand the effects of FSP on steel materials was also undertaken during the course of this project. Processed regions were created in high-strength, low-alloyed steels up to 0.5 in

  11. High efficiency diffusion molecular retention tumor targeting.

    PubMed

    Guo, Yanyan; Yuan, Hushan; Cho, Hoonsung; Kuruppu, Darshini; Jokivarsi, Kimmo; Agarwal, Aayush; Shah, Khalid; Josephson, Lee

    2013-01-01

    Here we introduce diffusion molecular retention (DMR) tumor targeting, a technique that employs PEG-fluorochrome shielded probes that, after a peritumoral (PT) injection, undergo slow vascular uptake and extensive interstitial diffusion, with tumor retention only through integrin molecular recognition. To demonstrate DMR, RGD (integrin binding) and RAD (control) probes were synthesized bearing DOTA (for (111) In(3+)), a NIR fluorochrome, and 5 kDa PEG that endows probes with a protein-like volume of 25 kDa and decreases non-specific interactions. With a GFP-BT-20 breast carcinoma model, tumor targeting by the DMR or i.v. methods was assessed by surface fluorescence, biodistribution of [(111)In] RGD and [(111)In] RAD probes, and whole animal SPECT. After a PT injection, both probes rapidly diffused through the normal and tumor interstitium, with retention of the RGD probe due to integrin interactions. With PT injection and the [(111)In] RGD probe, SPECT indicated a highly tumor specific uptake at 24 h post injection, with 352%ID/g tumor obtained by DMR (vs 4.14%ID/g by i.v.). The high efficiency molecular targeting of DMR employed low probe doses (e.g. 25 ng as RGD peptide), which minimizes toxicity risks and facilitates clinical translation. DMR applications include the delivery of fluorochromes for intraoperative tumor margin delineation, the delivery of radioisotopes (e.g. toxic, short range alpha emitters) for radiotherapy, or the delivery of photosensitizers to tumors accessible to light.

  12. High-Resolution pCO2 Record for the Cenomanian-Turonian OAE2 based on Fossil Plant Cuticle

    NASA Astrophysics Data System (ADS)

    Barclay, R. S.; Sageman, B. B.; McElwain, J. C.

    2008-12-01

    The Cenomanian-Turonian oceanic anoxic event 2 (OAE2) represents a major perturbation to the ocean- atmosphere-terrestrial system that lasted at least 600 ka. Marine extinction associated with OAE2 is thought to have occurred due to global marine anoxia, and increased primary production is the likely driver. However, the causal factors leading to increased production have remained poorly resolved. Recent research indicates that a pulse of submarine volcanism occurred in association with OAE2, and it has been suggested that this event led to overturn of the stratified ocean, possibly bringing P-rich deep waters to the surface. 208/204Pbinitial ratios taken from the Bonarelli horizon suggest that CO2 expelled by the volcanic event may have come from the Caribbean LIP. This is supported by a rapid negative shift in both 186/187Os and 87/86Sr isotopes just prior to OAE2, suggesting a marine source for the CO2 pulse. Some prior studies suggested that OAE2 resulted in a major drawdown of high ambient pCO2 levels. Only recently has a volcanic-sourced CO2 pulse been suggested for the event and its implications have yet to be fully explored. Two previous studies attempted to reconstruct pCO2 levels through OAE2 using geochemical proxy methods. Both studies show a decline in pCO2 at the onset of the δ13C excursion, but with decreases ranging from 140 to at least 400ppmV. Since neither study extended analyses to the interval preceding onset of the δ13C excursion it is difficult to assess the longer term trend. In addition, marine-based proxy methods contain large uncertainties that may be avoided in a non-marine proxy of pCO2, such as the stomatal frequency record of fossil plant cuticles. The stomatal based paleo-CO2 proxy relies on a genetically controlled inverse relationship between pCO2 and stomatal frequency in terrestrial plant leaves. Abundant plant cuticle is preserved in the paralic sections of the Dakota SS in SW Utah, which has been correlated to the Cenomanian

  13. 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.

  14. Novel High Efficient Organic Photovoltaic Materials

    NASA Technical Reports Server (NTRS)

    Sun, Sam; Haliburton, James; Fan, Zben; Taft, Charles; Wang, Yi-Qing; Maaref, Shahin; Mackey, Willie R. (Technical Monitor)

    2001-01-01

    In man's mission to the outer space or a remote site, the most abundant, renewable, nonpolluting, and unlimited external energy source is light. Photovoltaic (PV) materials can convert light into electrical power. In order to generate appreciable electrical power in space or on the Earth, it is necessary to collect sunlight from large areas due to the low density of sunlight, and this would be very costly using current commercially available inorganic solar cells. Future organic or polymer based solar cells seemed very attractive due to several reasons. These include lightweight, flexible shape, ultra-fast optoelectronic response time (this also makes organic PV materials attractive for developing ultra-fast photo detectors), tunability of energy band-gaps via molecular design, versatile materials synthesis and device fabrication schemes, and much lower cost on large-scale industrial production. It has been predicted that nano-phase separated block copolymer systems containing electron rich donor blocks and electron deficient acceptor blocks will facilitate the charge separation and migration due to improved electronic ultrastructure and morphology in comparison to current polymer composite photovoltaic system. This presentation will describe our recent progress in the design, synthesis and characterization of a novel donor-bridge-acceptor block copolymer system for potential high-efficient organic optoelectronic applications. Specifically, the donor block contains an electron donating alkyloxy derivatized polyphenylenevinylene, the acceptor block contains an electron withdrawing alkyl-sulfone derivatized polyphenylenevinylene, and the bridge block contains an electronically neutral non-conjugated aliphatic hydrocarbon chain. The key synthetic strategy includes the synthesis of each individual block first, then couple the blocks together. While the donor block stabilizes the holes, the acceptor block stabilizes the electrons. The bridge block is designed to hinder

  15. High efficiency waste to energy facility -- Pilot plant design

    SciTech Connect

    Orita, Norihiko; Kawahara, Yuuzou; Takahashi, Kazuyoshi; Yamauchi, Toru; Hosoda, Takuo

    1998-07-01

    Waste To Energy facilities are commonly acceptable to the environment and give benefits in two main areas: one is a hygienic waste disposal and another is waste heat energy recovery to save fossil fuel consumption. Recovered energy is used for electricity supply, and it is required to increase the efficiency of refuse to electric energy conversion, and to spread the plant construction throughout the country of Japan, by the government. The national project started in 1992, and pilot plant design details were established in 1995. The objective of the project is to get 30% of energy conversion efficiency through the measure by raising the steam temperature and pressure to 500 C and 9.8 MPa respectively. The pilot plant is operating under the design conditions, which verify the success of applied technologies. This paper describes key technologies which were used to design the refuse burning boiler, which generates the highest steam temperature and pressure steam.

  16. Selective flotation of fossil resin from western coal

    SciTech Connect

    Jensen, G.F.; Miller, J.D.

    1992-03-20

    The test program has demonstrated that: (1) technically, the new flotation technologies discovered at the University of Utah and then improved upon by Advanced Processing Technologies, Inc. provide a highly efficient means to selectively recover fossil resin from coal. The proof-of-concept continuous flotation circuit resulted in fossil resin recovery with the same separation efficiency as was obtained from laboratory bench-scale testing (more than 80% recovery at about 80% concentrate grade); and (2) economically, the selective flotation process has been shown to be sufficiently profitable to justify the development of a fossil resin industry based on this new flotation process. The proof-of-concept testing has resulted in significant interest from several coal mining companies and has sparked the desire of local and state government to establish a fossil resin industry in the Wasatch Plateau coal field. In this view, the results from the current proof-of-concept testing program have been successful. This special report provides theoretical and analytical data on some surface chemistry work pertinent to fossil resin characterization, and other efforts carried out during the past months.

  17. Proceedings of the eleventh annual conference on fossil energy materials

    SciTech Connect

    Judkins, R.R.

    1997-12-01

    The objective of the Advanced Research and Technology Development (AR and TD) Materials Program is to conduct research and development on materials for longer-term fossil energy applications as well as for generic needs of various fossil fuel technologies. These proceedings contain 34 papers organized under the following topical sections: Ceramic composites and functional materials; Ceramics, new alloys, and functional materials; and New alloys. Also included is a summary of a workshop on materials issues in low emission boilers and in high efficiency coal-fired cycles. Selected papers have been indexed separately for inclusion in the Energy Science and Technology Database.

  18. Counterfactual quantum key distribution with high efficiency

    SciTech Connect

    Sun Ying; Wen Qiaoyan

    2010-11-15

    In a counterfactual quantum key distribution scheme, a secret key can be generated merely by transmitting the split vacuum pulses of single particles. We improve the efficiency of the first quantum key distribution scheme based on the counterfactual phenomenon. This scheme not only achieves the same security level as the original one but also has higher efficiency. We also analyze how to achieve the optimal efficiency under various conditions.

  19. High efficiency crystalline silicon solar cells

    NASA Technical Reports Server (NTRS)

    Sah, C. T.

    1986-01-01

    The factors which may limit current crystalline silicon solar cells to less than 20 percent efficiency at AM 1 are investigated together with the factors which may limit the ultimate efficiency achievable. It was found that base recombination at residual defect and impurity recombination centers was the likely cause of the 20-percent efficiency barrier. Suggestions for design changes that would cut the losses due to recombinations are presented.

  20. A high-efficiency aerothermoelastic analysis method

    NASA Astrophysics Data System (ADS)

    Wan, ZhiQiang; Wang, YaoKun; Liu, YunZhen; Yang, Chao

    2014-06-01

    In this paper, a high-efficiency aerothermoelastic analysis method based on unified hypersonic lifting surface theory is established. The method adopts a two-way coupling form that couples the structure, aerodynamic force, and aerodynamic thermo and heat conduction. The aerodynamic force is first calculated based on unified hypersonic lifting surface theory, and then the Eckert reference temperature method is used to solve the temperature field, where the transient heat conduction is solved using Fourier's law, and the modal method is used for the aeroelastic correction. Finally, flutter is analyzed based on the p-k method. The aerothermoelastic behavior of a typical hypersonic low-aspect ratio wing is then analyzed, and the results indicate the following: (1) the combined effects of the aerodynamic load and thermal load both deform the wing, which would increase if the flexibility, size, and flight time of the hypersonic aircraft increase; (2) the effect of heat accumulation should be noted, and therefore, the trajectory parameters should be considered in the design of hypersonic flight vehicles to avoid hazardous conditions, such as flutter.

  1. Highly Efficient Contactless Electrical Energy Transmission System

    NASA Astrophysics Data System (ADS)

    Ayano, Hideki; Nagase, Hiroshi; Inaba, Hiromi

    This paper proposes a new concept for a contactless electrical energy transmission system for an elevator and an automated guided vehicle. The system has rechargeable batteries on the car and electrical energy is supplied at a specific place. When electric power is supplied to the car, it runs automatically and approaches the battery charger. Therefore, a comparatively large gap is needed between the primary transformer at the battery charger and the secondary transformer on the car in order to prevent damage which would be caused by a collision. In this case, a drop of the transformer coupling rate due to the large gap must be prevented. In conventional contactless electrical energy transmission technology, since electric power is received by a pick-up coil from a power line, a large-sized transformer is required. And when the distance over which the car runs is long, the copper loss of the line also increases. The developed system adopts a high frequency inverter using a soft switching method to miniaturize the transformer. The system has a coupling rate of 0.88 for a transformer gap length of 10mm and can operate at 91% efficiency.

  2. 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.

  3. Energy Efficient Graphene Based High Performance Capacitors.

    PubMed

    Bae, Joonwon; Lee, Chang-Soo; Kwon, Oh Seok

    2016-10-27

    Graphene (GRP) is an interesting class of nano-structured electronic materials for various cutting-edge applications. To date, extensive research activities have been performed on the investigation of diverse properties of GRP. The incorporation of this elegant material can be very lucrative in terms of practical applications in energy storage/conversion systems. Among various those systems, high performance electrochemical capacitors (ECs) have become popular due to the recent need for energy efficient and portable devices. Therefore, in this article, the application of GRP for capacitors is described succinctly. In particular, a concise summary on the previous research activities regarding GRP based capacitors is also covered extensively. It was revealed that a lot of secondary materials such as polymers and metal oxides have been introduced to improve the performance. Also, diverse devices have been combined with capacitors for better use. More importantly, recent patents related to the preparation and application of GRP based capacitors are also introduced briefly. This article can provide essential information for future study.

  4. High-Efficiency Klystron For Television Transmitters

    NASA Technical Reports Server (NTRS)

    Ramins, Peter; Dayton, James; Mccune, Earl, Sr.; Kosmahl, Henry

    1990-01-01

    Improved klystron designed for use as final amplifier in ultrahigh-frequency (UHF) television transmitter. New device incorporates multistage depressed collector (MSDC) of advanced design to increase efficiency by recovering, from spent electron beam, some of residual kinetic energy otherwise dissipated as heat. Concept applied to increase efficiencies of microwave communication, equipment, radar systems, and particle-beam accelerators.

  5. Highly skewed sex ratios and biased fossil deposition of moa: ancient DNA provides new insight on New Zealand's extinct megafauna

    NASA Astrophysics Data System (ADS)

    Allentoft, Morten E.; Bunce, Michael; Scofield, R. Paul; Hale, Marie L.; Holdaway, Richard N.

    2010-03-01

    Ancient DNA was isolated from the bones of 267 individuals of the extinct New Zealand moa (Aves: Dinornithiformes) from two late Holocene deposits [Pyramid Valley (PV) and Bell Hill Vineyard (BHV)] located 5.7 km apart in North Canterbury, South Island. The two sites' combined fossil record cover the last 3000 years of pre-human New Zealand and mitochondrial DNA confirmed that four species ( Dinornis robustus, Euryapteryx curtus, Emeus crassus, and Pachyornis elephantopus) were sympatric in the region. However, the relative species compositions in the two deposits differed significantly with D. robustus and E. crassus being most abundant at PV while E. curtus outnumbered the other three moa taxa combined at BHV. A subsample of 227 individuals had sufficient nuclear DNA preservation to warrant the use of molecular sexing techniques, and the analyses uncovered a remarkable excess of females in both deposits with an overall male to female ratio of 1:5.1. Among juveniles of E. curtus, the only species which was represented by a substantial fraction of juveniles, the sex ratio was not skewed (10 ♂, 10 ♀), suggesting that the observed imbalance arose as a result of differential mortality during maturation. Surprisingly, sex ratios proved significantly different between sites with a 1:2.2 ratio at BHV ( n = 90) and 1:14.2 at PV ( n = 137). Given the mobility of large ratites, and the proximity of the two fossil assemblages in space and time, these differences in taxonomic and gender composition indicate that moa biology and the local environment have affected the fossil representation dramatically and several possible explanations are offered. Apart from adding to our understanding of moa biology, these discoveries reinforce the need for caution when basing interpretation of the fossil record on material from a single site.

  6. High efficiency quasi-monochromatic infrared emitter

    NASA Astrophysics Data System (ADS)

    Brucoli, Giovanni; Bouchon, Patrick; Haïdar, Riad; Besbes, Mondher; Benisty, Henri; Greffet, Jean-Jacques

    2014-02-01

    Incandescent radiation sources are widely used as mid-infrared emitters owing to the lack of alternative for compact and low cost sources. A drawback of miniature hot systems such as membranes is their low efficiency, e.g., for battery powered systems. For targeted narrow-band applications such as gas spectroscopy, the efficiency is even lower. In this paper, we introduce design rules valid for very generic membranes demonstrating that their energy efficiency for use as incandescent infrared sources can be increased by two orders of magnitude.

  7. High efficiency quasi-monochromatic infrared emitter

    SciTech Connect

    Brucoli, Giovanni; Besbes, Mondher; Benisty, Henri Greffet, Jean-Jacques; Bouchon, Patrick; Haïdar, Riad

    2014-02-24

    Incandescent radiation sources are widely used as mid-infrared emitters owing to the lack of alternative for compact and low cost sources. A drawback of miniature hot systems such as membranes is their low efficiency, e.g., for battery powered systems. For targeted narrow-band applications such as gas spectroscopy, the efficiency is even lower. In this paper, we introduce design rules valid for very generic membranes demonstrating that their energy efficiency for use as incandescent infrared sources can be increased by two orders of magnitude.

  8. Cycles in fossil diversity

    SciTech Connect

    Rohde, Robert A.; Muller, Richard A.

    2004-10-20

    It is well-known that the diversity of life appears to fluctuate during the course the Phanerozoic, the eon during which hard shells and skeletons left abundant fossils (0-542 Ma). Using Sepkoski's compendium of the first and last stratigraphic appearances of 36380 marine genera, we report a strong 62 {+-} 3 Myr cycle, which is particularly strong in the shorter-lived genera. The five great extinctions enumerated by Raup and Sepkoski may be an aspect of this cycle. Because of the high statistical significance, we also consider contributing environmental factors and possible causes.

  9. Cycles in fossil diversity.

    PubMed

    Rohde, Robert A; Muller, Richard A

    2005-03-10

    It is well known that the diversity of life appears to fluctuate during the course of the Phanerozoic, the eon during which hard shells and skeletons left abundant fossils (0-542 million years ago). Here we show, using Sepkoski's compendium of the first and last stratigraphic appearances of 36,380 marine genera, a strong 62 +/- 3-million-year cycle, which is particularly evident in the shorter-lived genera. The five great extinctions enumerated by Raup and Sepkoski may be an aspect of this cycle. Because of the high statistical significance we also consider the contributions of environmental factors, and possible causes.

  10. High efficiency silicon solar cell review

    NASA Technical Reports Server (NTRS)

    Godlewski, M. P. (Editor)

    1975-01-01

    An overview is presented of the current research and development efforts to improve the performance of the silicon solar cell. The 24 papers presented reviewed experimental and analytic modeling work which emphasizes the improvment of conversion efficiency and the reduction of manufacturing costs. A summary is given of the round-table discussion, in which the near- and far-term directions of future efficiency improvements were discussed.

  11. A high-efficiency power cycle in which hydrogen is compressed by absorption in metal hydrides.

    PubMed

    Powell, J R; Salzano, F J; Yu, W S; Milau, J S

    1976-07-23

    A high-efficiency power cycle is proposed in which molecular hydrogen gas is used as a working fluid in a regenerative closed Brayton cycle. The hydrogen gas is compressed by an absorption-desorption cycle on metal hydride (FeTiH(x)) beds. Low-temperature solar or geothermal heat (temperature about 100 degrees C) is used for the compression process, and high-temperature fossil fuel or nuclear heat (temperature about 700 degrees C) supplies the expansion work in the turbine. Typically, about 90 percent of the high-temperature heat input is converted to electricity, while about 3 kilowatts of low-temperature heat is required per kilowatt of electrical output.

  12. High Efficiency Large Area Polysilicon Solar Cells

    NASA Technical Reports Server (NTRS)

    Johnson, S. M.; Winter, C.

    1985-01-01

    Large area (100 sq cm) polysilicon solar cells having efficiencies of up to 14.1% (100 mW/sq cm, 25 C) were fabricated and a detailed analysis was performed to identify the efficiency loss mechanisms. The 1-5 characteristics of the best cell were dominated by recombination in the quasi-neutral base due to the combination of minority carrier diffusion length and base resistivity. An analysis of the microstructural defects present in the material and their effect on the electrical properties is presented.

  13. High efficiency germanium-assisted grating coupler.

    PubMed

    Yang, Shuyu; Zhang, Yi; Baehr-Jones, Tom; Hochberg, Michael

    2014-12-15

    We propose a fiber to submicron silicon waveguide vertical coupler utilizing germanium-on-silicon gratings. The germanium is epitaxially grown on silicon in the same step for building photodetectors. Coupling efficiency based on FDTD simulation is 76% at 1.55 µm and the optical 1dB bandwidth is 40 nm.

  14. Novel Polymers for High Efficiency Renewable and Portable Power Applications

    DTIC Science & Technology

    2015-07-30

    force between the polymer and dye would result in weaker PL quenching and optoelectronic device power conversion efficiency, this experimentally...model. The results could be very useful for materials design for developing high efficiency organic and polymer based optoelectronic devices; 2) Optimum...Apr-2015 Approved for Public Release; Distribution Unlimited Final Report: Novel Polymers for High Efficiency Renewable and Portable Power

  15. Fossilized bioelectric wire - the trace fossil Trichichnus.

    PubMed

    Kędzierski, M; Uchman, A; Sawlowicz, Z; Briguglio, A

    2015-04-16

    The trace fossil Trichichnus is proposed as an indicator of fossil bioelectric bacterial activity at the oxic-anoxic interface zone of marine sediments. This fulfils the idea that such processes, commonly found in the modern realm, should be also present in the geological past. Trichichnus is an exceptional trace fossil due to its very thin diameter (mostly less than 1 mm) and common pyritic filling. It is ubiquitous in some fine-grained sediments, where it has been interpreted as a burrow formed deeper than any other trace fossils, below the redox boundary. Trichichnus, formerly referred to as deeply burrowed invertebrates, has been found as remnant of a fossilized intrasediment bacterial mat that is pyritized. As visualized in 3-D by means of X-ray computed microtomography scanner, Trichichnus forms dense filamentous fabric, which reflects that it is produced by modern large, mat-forming, sulfide-oxidizing bacteria, belonging mostly to Thioploca-related taxa, which are able to house a complex bacterial consortium. Several stages of Trichichnus formation, including filamentous, bacterial mat and its pyritization, are proposed to explain an electron exchange between oxic and suboxic/anoxic layers in the sediment. Therefore, Trichichnus can be considered a fossilized "electric wire".

  16. Fossilized bioelectric wire - the trace fossil Trichichnus

    NASA Astrophysics Data System (ADS)

    Kędzierski, M.; Uchman, A.; Sawlowicz, Z.; Briguglio, A.

    2014-12-01

    The trace fossil Trichichnus is proposed as an indicator of fossil bioelectric bacterial activity at the interface oxic - anoxic zone of marine sediments. This fulfils the idea that such processes, commonly found in the modern realm, should be also present in the geological past. Trichichnus is an exceptional trace fossil due to its very thin diameter (mostly less than 1 mm) and common pyritic filling. It is ubiquitous in some fine-grained sediments, where it has been interpreted as a burrow formed deeper than any other trace fossils, below the redox boundary. Trichichnus formerly referred to as deeply burrowed invertebrates, has been found as remnant of a fossilized intrasediment bacterial mat that is pyritized. As visualized in 3-D by means of X-ray computed microtomography scanner, Trichichnus forms dense filamentous fabric, which reflects that produced by modern large, mat-forming, sulphide-oxidizing bacteria, belonging mostly to Trichichnus-related taxa, which are able to house a complex bacterial consortium. Several stages of Trichichnus formation, including filamentous, bacterial mat and its pyritization, are proposed to explain an electron exchange between oxic and suboxic/anoxic layers in the sediment. Therefore, Trichichnus can be considered a fossilized "electric wire".

  17. Fossilized bioelectric wire - the trace fossil Trichichnus

    NASA Astrophysics Data System (ADS)

    Kędzierski, M.; Uchman, A.; Sawlowicz, Z.; Briguglio, A.

    2015-04-01

    The trace fossil Trichichnus is proposed as an indicator of fossil bioelectric bacterial activity at the oxic-anoxic interface zone of marine sediments. This fulfils the idea that such processes, commonly found in the modern realm, should be also present in the geological past. Trichichnus is an exceptional trace fossil due to its very thin diameter (mostly less than 1 mm) and common pyritic filling. It is ubiquitous in some fine-grained sediments, where it has been interpreted as a burrow formed deeper than any other trace fossils, below the redox boundary. Trichichnus, formerly referred to as deeply burrowed invertebrates, has been found as remnant of a fossilized intrasediment bacterial mat that is pyritized. As visualized in 3-D by means of X-ray computed microtomography scanner, Trichichnus forms dense filamentous fabric, which reflects that it is produced by modern large, mat-forming, sulfide-oxidizing bacteria, belonging mostly to Thioploca-related taxa, which are able to house a complex bacterial consortium. Several stages of Trichichnus formation, including filamentous, bacterial mat and its pyritization, are proposed to explain an electron exchange between oxic and suboxic/anoxic layers in the sediment. Therefore, Trichichnus can be considered a fossilized "electric wire".

  18. Energy efficiency indicators for high electric-load buildings

    SciTech Connect

    Aebischer, Bernard; Balmer, Markus A.; Kinney, Satkartar; Le Strat, Pascale; Shibata, Yoshiaki; Varone, Frederic

    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.

  19. High efficiency air cycle air conditioning system

    SciTech Connect

    Rannenberg, G. C.

    1985-11-19

    An air cycle air conditioning system is provided with regenerative heat exchangers upstream and downstream of an expansion turbine. A closedloop liquid circulatory system serially connects the two regenerative heat exchangers for regeneration without the bulk associated with air-to-air heat exchange. The liquid circulatory system may also provide heat transport to a remote sink heat exchanger and from a remote load as well as heat exchange within the sink heat exchanger and load for enhanced compactness and efficiency.

  20. High efficiency pump for space helium transfer

    NASA Technical Reports Server (NTRS)

    Hasenbein, Robert; Izenson, Michael G.; Swift, Walter L.; Sixsmith, Herbert

    1991-01-01

    A centrifugal pump was developed for the efficient and reliable transfer of liquid helium in space. The pump can be used to refill cryostats on orbiting satellites which use liquid helium for refrigeration at extremely low temperatures. The pump meets the head and flow requirements of on-orbit helium transfer: a flow rate of 800 L/hr at a head of 128 J/kg. The overall pump efficiency at the design point is 0.45. The design head and flow requirements are met with zero net positive suction head, which is the condition in an orbiting helium supply Dewar. The mass transfer efficiency calculated for a space transfer operation is 0.99. Steel ball bearings are used with gas fiber-reinforced teflon retainers to provide solid lubrication. These bearings have demonstrated the longest life in liquid helium endurance tests under simulated pumping conditions. Technology developed in the project also has application for liquid helium circulation in terrestrial facilities and for transfer of cryogenic rocket propellants in space.

  1. Uranium-series ages of fossil corals from Mallorca, Spain: The "Neotyrrhenian" high stand of the Mediterranean Sea revisited

    USGS Publications Warehouse

    Muhs, Daniel R.; Simmons, Kathleen R.; Porat, Naomi

    2015-01-01

    We analyzed corals from the Neotyrrhenian beds on Mallorca, which gave U-series ages from ~ 126 ka to ~ 118 ka. These ages are consistent with previously published amino acid data that show that the Neotyrrhenian and Eutyrrhenian deposits are not significantly different in age. A fossil molluscan fauna from the Neotyrrhenian deposits on Mallorca has a warm-water paleozoogeographic aspect, with nine southward-ranging species and four extralimital southern species. When compared with sea surface temperatures obtained from planktonic foraminifera and alkenones from ODP core 977 in the nearby Alboran Sea, the only time period that shows comparable warmth is MIS 5.5/5e, consistent with the U-series ages of corals from the Neotyrrhenian deposits. We propose that the Neotyrrhenian deposits are a beachrock facies of the same age as the Eutyrrhenian deposits. This interpretation is consistent with the differences in physical sedimentology of the two deposits, explains the U-series and amino acid data indicating the same age, is consistent with the very slight elevation difference of the Neotyrrhenian and Eutyrrhenian beds, and explains the similar, though not identical paleozoogeographic aspects of their fossil faunas.

  2. Fossil Microorganisms in Archaean

    NASA Technical Reports Server (NTRS)

    Astafleva, Marina; Hoover, Richard; Rozanov, Alexei; Vrevskiy, A.

    2006-01-01

    Ancient Archean and Proterozoic rocks are the model objects for investigation of rocks comprising astromaterials. The first of Archean fossil microorganisms from Baltic shield have been reported at the last SPIE Conference in 2005. Since this confeence biomorphic structures have been revealed in Archean rocks of Karelia. It was determined that there are 3 types of such bion structures: 1. structures found in situ, in other words microorganisms even-aged with rock matrix, that is real Archean fossils biomorphic structures, that is to say forms inhabited early formed rocks, and 3. younger than Archean-Protherozoic minerali microorganisms, that is later contamination. We made attempt to differentiate these 3 types of findings and tried to understand of burial of microorganisms. The structures belongs (from our point of view) to the first type, or real Archean, forms were under examination. Practical investigation of ancient microorganisms from Green-Stone-Belt of Northern Karelia turns to be very perspective. It shows that even in such ancient time as Archean ancient diverse world existed. Moreover probably such relatively highly organized cyanobacteria and perhaps eukaryotic formes existed in Archean world.

  3. PMMA lens with high efficiency and reliability

    NASA Astrophysics Data System (ADS)

    Matsuzaki, Ichiro; Abe, Koji; Fujita, Katsuhiro

    2013-09-01

    Polymethyl Methacrylate (PMMA) Fresnel lenses are increasingly being used in concentrated photovoltaic (CPV) systems installed outdoors and, accordingly, emphasis is being placed on the durability of such lenses with regard to light transmittance when subject to ultraviolet (UV) light and dust exposure. Accelerated testing methods for evaluating durability under UV exposure were established, allowing development of a lens material with improved UV resistance. Simultaneously, through a proprietary molding method, a Fresnel lens that boasts favorable light concentration efficiency with little deformation even after prolonged outdoor use was developed. Moreover, the lens incorporates a new hard-coat finish that possesses sand durability and UV resistance comparable to that of tempered glass.

  4. High Efficiency Thermoelectric Radioisotope Power Systems

    NASA Technical Reports Server (NTRS)

    El-Genk, Mohamed; Saber, Hamed; Caillat, Thierry

    2004-01-01

    The work performed and whose results presented in this report is a joint effort between the University of New Mexico s Institute for Space and Nuclear Power Studies (ISNPS) and the Jet Propulsion Laboratory (JPL), California Institute of Technology. In addition to the development, design, and fabrication of skutterudites and skutterudites-based segmented unicouples this effort included conducting performance tests of these unicouples for hundreds of hours to verify theoretical predictions of the conversion efficiency. The performance predictions of these unicouples are obtained using 1-D and 3-D models developed for that purpose and for estimating the actual performance and side heat losses in the tests conducted at ISNPS. In addition to the performance tests, the development of the 1-D and 3-D models and the development of Advanced Radioisotope Power systems for Beginning-Of-Life (BOM) power of 108 We are carried out at ISNPS. The materials synthesis and fabrication of the unicouples are carried out at JPL. The research conducted at ISNPS is documented in chapters 2-5 and that conducted at JP, in documented in chapter 5. An important consideration in the design and optimization of segmented thermoelectric unicouples (STUs) is determining the relative lengths, cross-section areas, and the interfacial temperatures of the segments of the different materials in the n- and p-legs. These variables are determined using a genetic algorithm (GA) in conjunction with one-dimensional analytical model of STUs that is developed in chapter 2. Results indicated that when optimized for maximum conversion efficiency, the interfacial temperatures between various segments in a STU are close to those at the intersections of the Figure-Of-Merit (FOM), ZT, curves of the thermoelectric materials of the adjacent segments. When optimizing the STUs for maximum electrical power density, however, the interfacial temperatures are different from those at the intersections of the ZT curves, but

  5. New type of transformerless high efficiency inverter

    NASA Astrophysics Data System (ADS)

    Naaijer, G. J.

    Inverter architectures are presented which allow economical ac/dc switching for solar cell array and battery power use in domestic and industrial applications. The efficiencies of currently available inverters are examined and compared with a new 2.2 kW transformerless stepped wave inverter. The inverter has low no-load losses, amounting to 200 Wh/24 hr, and features voltage steps occurring 15-30 times/sine wave period. An example is provided for an array/battery/inverter assembly with the inverter control electronics activating or disconnecting the battery subassemblies based on the total number of activated subassemblies in relation to a reference sinewave, and the need to average the battery subassembly discharge rates. A total harmonic distortion of 6 percent was observed, and the system is noted to be usable as a battery charger.

  6. Development of high efficiency neutron detectors

    SciTech Connect

    Pickrell, M.M.; Menlove, H.O.

    1993-08-01

    We have designed a novel neutron detector system using conventional {sup 3}He detector tubes and composites of polyethylene, and graphite. At this time the design consists entirely of MCNP simulations of different detector configurations and materials. These detectors are applicable to low-level passive and active neutron assay systems such as the passive add-a-source and the {sup 252}Cf shuffler. Monte Carlo simulations of these neutron detector designs achieved efficiencies of over 35% for assay chambers that can accommodate 55-gal. drums. Only slight increases in the number of detector tubes and helium pressure are required. The detectors also have reduced die-away times. Potential applications are coincident and multiplicity neutron counting for waste disposal and safeguards. We will present the general design philosophy, underlying physics, calculation mechanics, and results.

  7. High-efficiency thermoelectrics with functionalized graphene.

    PubMed

    Kim, Jeong Yun; Grossman, Jeffrey C

    2015-05-13

    Graphene superlattices made with chemical functionalization offer the possibility of tuning both the thermal and electronic properties via nanopatterning of the graphene surface. Using classical and quantum mechanical calculations, we predict that suitable chemical functionalization of graphene can introduce peaks in the density of states at the band edge that result in a large enhancement in the Seebeck coefficient, leading to an increase in the room-temperature power factor of a factor of 2 compared to pristine graphene, despite the degraded electrical conductivity. Furthermore, the presence of patterns on graphene reduces the thermal conductivity, which when taken together leads to an increase in the figure of merit for functionalized graphene by up to 2 orders of magnitude over that of pristine graphene, reaching its maximum ZT ∼ 3 at room temperature according to our calculations. These results suggest that appropriate chemical functionalization could lead to efficient graphene-based thermoelectric materials.

  8. High Efficiency Transverse D. C. Electron Beams.

    DTIC Science & Technology

    1984-10-01

    cathode er pressures is also possible, however, the electron beam be- materials. For example, copper beryllium has a high secon- comes poorly collimated as...50-50% by weight 0.6 acceptable Molybdenum-MgO 6. Graphite 0.1 low 7. Copper 0.05 very high .1 8. Copper- beryllium 98-2% 0.05 very high 9. Stainless...reached 10% of the initial value at a total energy of BEAM S HEET 725 J/cm2. Annealing of doped polysilicon and silicide films was also achieved. Fig

  9. 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.

  10. Highly efficient multimode diode-pumped Yb:KYW laser

    NASA Astrophysics Data System (ADS)

    Kuznetsov, S. A.; Pivtsov, V. S.; Semenko, A. V.; Bagayev, S. N.

    2017-01-01

    Record high differential efficiency (53.2%) and full optical efficiency (48%) for a multimode diode-pumped Yb:KYW laser have been achieved. The characteristics of the laser and methods for improving its efficiency using a distributed Bragg reflector tapered diode laser (DBR TDL) are discussed.

  11. Do alternative energy sources displace fossil fuels?

    NASA Astrophysics Data System (ADS)

    York, Richard

    2012-06-01

    A fundamental, generally implicit, assumption of the Intergovernmental Panel on Climate Change reports and many energy analysts is that each unit of energy supplied by non-fossil-fuel sources takes the place of a unit of energy supplied by fossil-fuel sources. However, owing to the complexity of economic systems and human behaviour, it is often the case that changes aimed at reducing one type of resource consumption, either through improvements in efficiency of use or by developing substitutes, do not lead to the intended outcome when net effects are considered. Here, I show that the average pattern across most nations of the world over the past fifty years is one where each unit of total national energy use from non-fossil-fuel sources displaced less than one-quarter of a unit of fossil-fuel energy use and, focusing specifically on electricity, each unit of electricity generated by non-fossil-fuel sources displaced less than one-tenth of a unit of fossil-fuel-generated electricity. These results challenge conventional thinking in that they indicate that suppressing the use of fossil fuel will require changes other than simply technical ones such as expanding non-fossil-fuel energy production.

  12. Modes of fossil preservation

    USGS Publications Warehouse

    Schopf, J.M.

    1975-01-01

    The processes of geologic preservation are important for understanding the organisms represented by fossils. Some fossil differences are due to basic differences in organization of animals and plants, but the interpretation of fossils has also tended to be influenced by modes of preservation. Four modes of preservation generally can be distinguished: (1) Cellular permineralization ("petrifaction") preserves anatomical detail, and, occasionally, even cytologic structures. (2) Coalified compression, best illustrated by structures from coal but characteristic of many plant fossils in shale, preserves anatomical details in distorted form and produces surface replicas (impressions) on enclosing matrix. (3) Authigenic preservation replicates surface form or outline (molds and casts) prior to distortion by compression and, depending on cementation and timing, may intergrade with fossils that have been subject to compression. (4) Duripartic (hard part) preservation is characteristic of fossil skeletal remains, predominantly animal. Molds, pseudomorphs, or casts may form as bulk replacements following dissolution of the original fossil material, usually by leaching. Classification of the kinds of preservation in fossils will aid in identifying the processes responsible for modifying the fossil remains of both animals and plants. ?? 1975.

  13. Preparation of highly efficient manganese catalase mimics.

    PubMed

    Triller, Michael U; Hsieh, Wen-Yuan; Pecoraro, Vincent L; Rompel, Annette; Krebs, Bernt

    2002-10-21

    The series of compounds [Mn(bpia)(mu-OAc)](2)(ClO(4))(2) (1), [Mn(2)(bpia)(2)(muO)(mu-OAc)](ClO(4))(3).CH(3)CN (2), [Mn(bpia)(mu-O)](2)(ClO(4))(2)(PF(6)).2CH(3)CN (3), [Mn(bpia)(Cl)(2)](ClO)(4) (4), and [(Mn(bpia)(Cl))(2)(mu-O)](ClO(4))(2).2CH(3)CN (5) (bpia = bis(picolyl)(N-methylimidazol-2-yl)amine) represents a structural, spectroscopic, and functional model system for manganese catalases. Compounds 3 and 5 have been synthesized from 2 via bulk electrolysis and ligand exchange, respectively. All complexes have been structurally characterized by X-ray crystallography and by UV-vis and EPR spectroscopies. The different bridging ligands including the rare mono-mu-oxo and mono-mu-oxo-mono-mu-carboxylato motifs lead to a variation of the Mn-Mn separation across the four binuclear compounds of 1.50 A (Mn(2)(II,II) = 4.128 A, Mn(2)(III,III) = 3.5326 and 3.2533 A, Mn(2)(III,IV) = 2.624 A). Complexes 1, 2, and 3 are mimics for the Mn(2)(II,II), the Mn(2)(III,III), and the Mn(2)(III,IV) oxidation states of the native enzyme. UV-vis spectra of these compounds show similarities to those of the corresponding oxidation states of manganese catalase from Thermus thermophilus and Lactobacillus plantarum. Compound 2 exhibits a rare example of a Jahn-Teller compression. While complexes 1 and 3 are efficient catalysts for the disproportionation of hydrogen peroxide and contain an N(4)O(2) donor set, 4 and 5 show no catalase activity. These complexes have an N(4)Cl(2) and N(4)OCl donor set, respectively, and serve as mimics for halide inhibited manganese catalases. Cyclovoltammetric data show that the substitution of oxygen donor atoms with chloride causes a shift of redox potentials to more positive values. To our knowledge, complex 1 is the most efficient binuclear functional manganese catalase mimic exhibiting saturation kinetics to date.

  14. 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.

  15. Efficient high-capacity steganography technique

    NASA Astrophysics Data System (ADS)

    Abdulla, Alan A.; Jassim, Sabah A.; Sellahewa, Harin

    2013-05-01

    Performance indicators characterizing modern steganographic techniques include capacity (i.e. the quantity of data that can be hidden in the cover medium), stego quality (i.e. artifacts visibility), security (i.e. undetectability), and strength or robustness (intended as the resistance against active attacks aimed to destroy the secret message). Fibonacci based embedding techniques have been researched and proposed in the literature to achieve efficient steganography in terms of capacity with respect to stego quality. In this paper, we investigated an innovative idea that extends Fibonacci-like steganography by bit-plane(s) mapping instead of bit-plane(s) replacement. Our proposed algorithm increases embedding capacity using bit-plane mapping to embed two bits of the secret message in three bits of a pixel of the cover, at the expense of a marginal loss in stego quality. While existing Fibonacci embedding algorithms do not use certain intensities of the cover for embedding due to the limitation imposed by the Zeckendorf theorem, our proposal solve this problem and make all intensity values candidates for embedding. Experimental results demonstrate that the proposed technique double the embedding capacity when compared to existing Fibonacci methods, and it is secure against statistical attacks such as RS, POV, and difference image histogram (DIH).

  16. Interfacial Engineering for Highly Efficient-Conjugated Polymer-Based Bulk Heterojunction Photovoltaic Devices

    SciTech Connect

    Alex Jen; David Ginger; Christine Luscombe; Hong Ma

    2012-04-02

    The aim of our proposal is to apply interface engineering approach to improve charge extraction, guide active layer morphology, improve materials compatibility, and ultimately allow the fabrication of high efficiency tandem cells. Specifically, we aim at developing: i. Interfacial engineering using small molecule self-assembled monolayers ii. Nanostructure engineering in OPVs using polymer brushes iii. Development of efficient light harvesting and high mobility materials for OPVs iv. Physical characterization of the nanostructured systems using electrostatic force microscopy, and conducting atomic force microscopy v. All-solution processed organic-based tandem cells using interfacial engineering to optimize the recombination layer currents vi. Theoretical modeling of charge transport in the active semiconducting layer The material development effort is guided by advanced computer modeling and surface/ interface engineering tools to allow us to obtain better understanding of the effect of electrode modifications on OPV performance for the investigation of more elaborate device structures. The materials and devices developed within this program represent a major conceptual advancement using an integrated approach combining rational molecular design, material, interface, process, and device engineering to achieve solar cells with high efficiency, stability, and the potential to be used for large-area roll-to-roll printing. This may create significant impact in lowering manufacturing cost of polymer solar cells for promoting clean renewable energy use and preventing the side effects from using fossil fuels to impact environment.

  17. High Efficiency Micromachining System Applied in Nanolithography

    NASA Astrophysics Data System (ADS)

    Chen, Xing; Lee, Dong Weon; Choi, Young Soo

    Scanning probe lithography such as direct-writing lithographic processes and nanoscratching techniques based on scanning probe microscopy have presented new micromachining methods for microelectromechanical system (MEMS). In this paper, a micromachining system for thermal scanning probe lithography is introduced, which consists of the cantilever arrays and a big stroke micro XY-stage. A large machining area and high machining speed can be realized by combining arrays of cantilevers possessing sharp tips at their top with the novel micro XY-stage which can obtain big displacements under relatively low driving voltage and in a small size. According to the above configuration, this micromachining system is provided with high throughputs and suitable for industrialization due to its MEMS-based simple fabrication process. The novel micro XY-stage applied in this system is presented in detail including the unique structure and principles, which shows an obvious improvement and distinct advantages in comparison with traditional structures. It is analyzed by mathematical model and then simulated using finite element method (FEM), it is proved to be able to practically serve the micromachining system with high capability.

  18. Biologically inspired highly efficient buoyancy engine

    NASA Astrophysics Data System (ADS)

    Akle, Barbar; Habchi, Wassim; Abdelnour, Rita; Blottman, John, III; Leo, Donald

    2012-04-01

    Undersea distributed networked sensor systems require a miniaturization of platforms and a means of both spatial and temporal persistence. One aspect of this system is the necessity to modulate sensor depth for optimal positioning and station-keeping. Current approaches involve pneumatic bladders or electrolysis; both require mechanical subsystems and consume significant power. These are not suitable for the miniaturization of sensor platforms. Presented in this study is a novel biologically inspired method that relies on ionic motion and osmotic pressures to displace a volume of water from the ocean into and out of the proposed buoyancy engine. At a constant device volume, the displaced water will alter buoyancy leading to either sinking or floating. The engine is composed of an enclosure sided on the ocean's end by a Nafion ionomer and by a flexible membrane separating the water from a gas enclosure. Two electrodes are placed one inside the enclosure and the other attached to the engine on the outside. The semi-permeable membrane Nafion allows water motion in and out of the enclosure while blocking anions from being transferred. The two electrodes generate local concentration changes of ions upon the application of an electrical field; these changes lead to osmotic pressures and hence the transfer of water through the semi-permeable membrane. Some aquatic organisms such as pelagic crustacean perform this buoyancy control using an exchange of ions through their tissue to modulate its density relative to the ambient sea water. In this paper, the authors provide an experimental proof of concept of this buoyancy engine. The efficiency of changing the engine's buoyancy is calculated and optimized as a function of electrode surface area. For example electrodes made of a 3mm diameter Ag/AgCl proved to transfer approximately 4mm3 of water consuming 4 Joules of electrical energy. The speed of displacement is optimized as a function of the surface area of the Nafion

  19. High efficiency radioisotope thermophotovoltaic prototype generator

    NASA Technical Reports Server (NTRS)

    Avery, James E.; Samaras, John E.; Fraas, Lewis M.; Ewell, Richard

    1995-01-01

    250 Watts of heat input, we expect this prototype to produce over 300 Watts of electrical energy output for a system energy conversion efficiency of over 12%. This low risk, near term design provides advances relative to present radioisotope thermophotovoltaic generators and has the additional advantage of allowing component and system development and testing to begin immediately. Improved cells and filters can easily be incorporated in this baseline system if they should become available in the future.

  20. High Efficiency, High Density Terrestrial Panel. [for solar cell modules

    NASA Technical Reports Server (NTRS)

    Wohlgemuth, J.; Wihl, M.; Rosenfield, T.

    1979-01-01

    Terrestrial panels were fabricated using rectangular cells. Packing densities in excess of 90% with panel conversion efficiencies greater than 13% were obtained. Higher density panels can be produced on a cost competitive basis with the standard salami panels.

  1. 40 CFR 761.71 - High efficiency boilers.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false High efficiency boilers. 761.71... PROHIBITIONS Storage and Disposal § 761.71 High efficiency boilers. (a) To burn mineral oil dielectric fluid containing a PCB concentration of ≥50 ppm, but boiler shall comply with the...

  2. 40 CFR 761.71 - High efficiency boilers.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false High efficiency boilers. 761.71... PROHIBITIONS Storage and Disposal § 761.71 High efficiency boilers. (a) To burn mineral oil dielectric fluid containing a PCB concentration of ≥50 ppm, but boiler shall comply with the...

  3. 40 CFR 761.71 - High efficiency boilers.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false High efficiency boilers. 761.71... PROHIBITIONS Storage and Disposal § 761.71 High efficiency boilers. (a) To burn mineral oil dielectric fluid containing a PCB concentration of ≥50 ppm, but boiler shall comply with the...

  4. 40 CFR 761.71 - High efficiency boilers.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false High efficiency boilers. 761.71... PROHIBITIONS Storage and Disposal § 761.71 High efficiency boilers. (a) To burn mineral oil dielectric fluid containing a PCB concentration of ≥50 ppm, but boiler shall comply with the...

  5. High efficiency low cost GaAs/Ge cell technology

    NASA Technical Reports Server (NTRS)

    Ho, Frank

    1990-01-01

    Viewgraphs on high efficiency low cost GaAs/Ge cell technology are presented. Topics covered include: high efficiency, low cost GaAs/Ge solar cells; advantages of Ge; comparison of typical production cells for space applications; panel level comparisons; and solar cell technology trends.

  6. HIGH EFFICIENCY DESULFURIZATION OF SYNTHESIS GAS

    SciTech Connect

    Anirban Mukherjee; Kwang-Bok Yi; Elizabeth J. Podlaha; Douglas P. Harrison

    2001-11-01

    Mixed metal oxides containing CeO{sub 2} and ZrO{sub 2} are being studied as high temperature desulfurization sorbents capable of achieving the DOE Vision 21 target of 1 ppmv of less H{sub 2}S. The research is justified by recent results in this laboratory that showed that reduced CeO{sub 2}, designated CeO{sub n} (1.5 < n < 2.0), is capable of achieving the 1 ppmv target in highly reducing gas atmospheres. The addition of ZrO{sub 2} has improved the performance of oxidation catalysts and three-way automotive catalysts containing CeO{sub 2}, and should have similar beneficial effects on CeO{sub 2} desulfurization sorbents. An electrochemical method for synthesizing CeO{sub 2}-ZrO{sub 2} has been developed and the products have been characterized by XRD and TEM during year 01. Nanocrystalline particles having a diameter of about 5 nm and containing from approximately 10 mol% to 80 mol% ZrO{sub 2} have been prepared. XRD showed the product to be a solid solution at low ZrO{sub 2} contents with a separate ZrO{sub 2} phase emerging at higher ZrO{sub 2} levels. Phase separation did not occur when the solid solutions were heat treated at 700 C. A flow reactor system constructed of quartz and teflon has been constructed, and a gas chromatograph equipped with a pulsed flame photometric detector (PFPD) suitable for measuring sub-ppmv levels of H{sub 2}S has been purchased with LSU matching funds. Preliminary desulfurization tests using commercial CeO{sub 2} and CeO{sub 2}-ZrO{sub 2} in highly reducing gas compositions has confirmed that CeO{sub 2}-ZrO{sub 2} is more effective than CeO{sub 2} in removing H{sub 2}S. At 700 C the product H{sub 2}S concentration using CeO{sub 2}-ZrO{sub 2} sorbent was near the 0.1 ppmv PFPD detection limit during the prebreakthrough period.

  7. Compact and highly efficient laser pump cavity

    DOEpatents

    Chang, Jim J.; Bass, Isaac L.; Zapata, Luis E.

    1999-01-01

    A new, compact, side-pumped laser pump cavity design which uses non-conventional optics for injection of laser-diode light into a laser pump chamber includes a plurality of elongated light concentration channels. In one embodiment, the light concentration channels are compound parabolic concentrators (CPC) which have very small exit apertures so that light will not escape from the pumping chamber and will be multiply reflected through the laser rod. This new design effectively traps the pump radiation inside the pump chamber that encloses the laser rod. It enables more uniform laser pumping and highly effective recycle of pump radiation, leading to significantly improved laser performance. This new design also effectively widens the acceptable radiation wavelength of the diodes, resulting in a more reliable laser performance with lower cost.

  8. High-elevation late Pleistocene (MIS 6-5) vertebrate faunas from the Ziegler Reservoir fossil site, Snowmass Village, Colorado

    NASA Astrophysics Data System (ADS)

    Sertich, Joseph J. W.; Stucky, Richard K.; McDonald, H. Gregory; Newton, Cody; Fisher, Daniel C.; Scott, Eric; Demboski, John R.; Lucking, Carol; McHorse, Brianna K.; Davis, Edward B.

    2014-11-01

    The vertebrate record at the Ziegler Reservoir fossil site (ZRFS) near Snowmass Village, Colorado ranges from ~ 140 to 77 ka, spanning all of Marine Oxygen Isotope Stage (MIS) 5. The site contains at least 52 taxa of macro- and microvertebrates, including one fish, three amphibian, four reptile, ten bird, and 34 mammal taxa. The most common vertebrate is Ambystoma tigrinum (tiger salamander), which is represented by > 22,000 elements representing the entire life cycle. The mastodon, Mammut americanum, is the most common mammal, and is documented by > 1800 skeletal elements making the ZRFS one of the largest accumulations of proboscidean remains in North America. Faunas at the ZRFS can be divided into two groups, a lake-margin group dating to ~ 140-100 ka that is dominated by woodland taxa, and a lake-center group dating to ~ 87-77 ka characterized by taxa favoring more open conditions. The change in faunal assemblages occurred between MIS 5c and 5a (vertebrates were absent from MIS 5b deposits), which were times of significant environmental change at the ZRFS. Furthermore, the ZRFS provides a well-dated occurrence of the extinct Bison latifrons, which has implications for the timing of the Rancholabrean Mammal Age in the region.

  9. 2250-MHz High Efficiency Microwave Power Amplifier (HEMPA)

    NASA Technical Reports Server (NTRS)

    Sims, W. Herbert; Bell, Joseph L. (Technical Monitor)

    2001-01-01

    Tnis paper will focus on developing an exotic switching technique that enhances the DC-to-RF conversion efficiency of microwave power amplifiers. For years, switching techniques implemented in the 10 kHz to 30 MHz region have resulted in DC-to-RF conversion efficiencies of 90-95-percent. Currently amplifier conversion efficiency, in the 2-3 GHz region approaches, 10-20-percent. Using a combination of analytical modeling and hardware testing, a High Efficiency Microwave Power Amplifier was built that demonstrated conversion efficiencies four to five times higher than current state of the art.

  10. High Efficiency Generation of Hydrogen Fuels using Nuclear Power Annual Report August, 2000 - July 2001

    SciTech Connect

    Brown, L.C.

    2002-11-01

    OAK B188 High Efficiency Generation of Hydrogen Fuels using Nuclear Power Annual Report August 2000 - July 2001. Currently no large scale, cost-effective, environmentally attractive hydrogen production process is available for commercialization nor has such a process been identified. Hydrogen is a promising energy carrier, which potentially could replace the fossil fuels used in the transportation sector of our economy. Carbon dioxide emissions from fossil fuel combustion are thought to be responsible for global warming. The purpose of this work is to determine the potential for efficient, cost-effective, large-scale production of hydrogen utilizing high temperature heat from an advanced nuclear power station. The benefits of this work will include the generation of a low-polluting transportable energy feedstock in an efficient method that has little or no implication for greenhouse gas emissions from a primary energy source whose availability and sources are domestically controlled. This will help to ensure energy for a future transportation/energy infrastructure that is not influenced/controlled by foreign governments. This report describes work accomplished during the second year (Phase 2) of a three year project whose objective is to ''define an economically feasible concept for production of hydrogen, by nuclear means, using an advanced high temperature nuclear reactor as the energy source.'' The emphasis of the first year (Phase 1) was to evaluate thermochemical processes which offer the potential for efficient, cost-effective, large-scale production of hydrogen from water, in which the primary energy input is high temperature heat from an advanced nuclear reactor and to select one (or, at most, three) for further detailed consideration. Phase 1 met its goals and did select one process, the sulfur-iodine process, for investigation in Phases 2 and 3. The combined goals of Phases 2 and 3 were to select the advanced nuclear reactor best suited to driving the

  11. The dilemma of fossil fuel use and global climate change

    SciTech Connect

    Judkins, R.R.; Fulkerson, W. ); Sanghvi, M.K. )

    1991-01-01

    The use of fossil fuels and relationship to climate change is discussed. As the use of fossil fuels has grown, the problems of protecting the environment and human health and safety have also grown, providing a continuing challenge to technological and managerial innovation. Today that challenge is to control atmospheric emissions from combustion, particularly those emissions that cause acidic deposition, urban pollution, and increasing concentrations of greenhouse gases. Technology for reducing acidic deposition is available and needs only to be adopted, and the remedies for urban pollution are being developed and tested. How effective or expensive these will be remains to be determined. The control of emissions of the greenhouse gas, CO{sub 2}, seems possible only be reducing the total amounts of fossil fuels used worldwide, and by substituting efficient natural gas technologies for coal. Long before physical depletion forces the transition away from fossil fuels, it is at least plausible and even likely that the greenhouse effect will impose a show-stopping constraint. If such a transition were soon to be necessary, the costs would be very high because substitute energy sources are either limited or expensive or undesirable for other reasons. Furthermore, the costs would be unevenly felt and would be more oppressive for developing nations because they would be least able to pay and, on average, their use rates of fossil fuels are growing much faster than those of many industrialized countries. It is prudent, therefore, to try to manage the use of fossil fuels as if a greenhouse constraint is an important possibility.

  12. HIGH EFFICIENCY DESULFURIZATION OF SYNTHESIS GAS

    SciTech Connect

    Kwang-Bok Yi; Anirban Mukherjee; Elizabeth J. Podlaha; Douglas P. Harrison

    2004-03-01

    Mixed metal oxides containing ceria and zirconia have been studied as high temperature desulfurization sorbents with the objective of achieving the DOE Vision 21 target of 1 ppmv or less H{sub 2}S in the product gas. The research was justified by recent results in this laboratory that showed that reduced CeO{sub 2}, designated CeOn (1.5 < n < 2.0), is capable of achieving the 1 ppmv target in highly reducing gas atmospheres. The addition of ZrO{sub 2} has improved the performance of oxidation catalysts and three-way automotive catalysts containing CeO{sub 2}, and was postulated to have similar beneficial effects on CeO{sub 2} desulfurization sorbents. An electrochemical method for synthesizing CeO{sub 2}-ZrO{sub 2} mixtures was developed and the products were characterized by XRD and TEM during year 01. Nanocrystalline particles having a diameter of about 5 nm and containing from approximately 10 mol% to 80 mol% ZrO{sub 2} were prepared. XRD analysis showed the product to be a solid solution at low ZrO{sub 2} contents with a separate ZrO{sub 2} phase emerging at higher ZrO{sub 2} levels. Unfortunately, the quantity of CeO{sub 2}-ZrO{sub 2} that could be prepared electrochemically was too small to permit desulfurization testing. Also during year 01 a laboratory-scale fixed-bed reactor was constructed for desulfurization testing. All components of the reactor and analytical systems that were exposed to low concentrations of H{sub 2}S were constructed of quartz, Teflon, or silcosteel. Reactor product gas composition as a function of time was determined using a Varian 3800 gas chromatograph equipped with a pulsed flame photometric detector (PFPD) for measuring low H{sub 2}S concentrations from approximately 0.1 to 10 ppmv, and a thermal conductivity detector (TCD) for higher concentrations of H{sub 2}S. Larger quantities of CeO{sub 2}-ZrO{sub 2} mixtures from other sources, including mixtures prepared in this laboratory using a coprecipitation procedure, were obtained

  13. HIGH EFFICIENCY DESULFURIZATION OF SYNTHESIS GAS

    SciTech Connect

    Kwang-Bok Yi; Elizabeth J. Podlaha; Douglas P. Harrison

    2003-11-01

    Mixed metal oxides containing CeO{sub 2} and ZrO{sub 2} are being studied as high temperature desulfurization sorbents capable of achieving the DOE Vision 21 target of 1 ppmv or less H{sub 2}S. The research is justified by recent results in this laboratory that showed that reduced CeO{sub 2}, designated CeOn (1.5 < n < 2.0), is capable of achieving the 1 ppmv target in highly reducing gas atmospheres. The addition of ZrO{sub 2} has improved the performance of oxidation catalysts and three-way automotive catalysts containing CeO{sub 2}, and should have similar beneficial effects on CeO{sub 2} desulfurization sorbents. An electrochemical method for synthesizing CeO{sub 2}-ZrO{sub 2} was developed and the products were characterized by XRD and TEM during year 01. Nanocrystalline particles having a diameter of about 5 nm and containing from approximately 10 mol% to 80 mol% ZrO{sub 2} were prepared. XRD analysis showed the product to be a solid solution at low ZrO{sub 2} contents with a separate ZrO{sub 2} phase emerging at higher ZrO{sub 2} levels. Unfortunately, the quantity of CeO{sub 2}-ZrO{sub 2} that could be prepared electrochemically was too small to permit full desulfurization testing. Also during year 01 a laboratory-scale fixed-bed reactor was constructed for desulfurization testing. All components of the reactor and analytical systems that may be exposed to low concentrations of H{sub 2}S are constructed of quartz, Teflon, or silcosteel. Reactor product gas composition as a function of time is determined using a Varian 3800 gas chromatograph equipped with a pulsed flame photometric detector (PFPD) for measuring low H{sub 2}S concentrations (<{approx}10 ppmv) and a thermal conductivity detector (TCD) for higher concentrations of H{sub 2}S. Larger quantities of CeO{sub 2}-ZrO{sub 2} mixtures from other sources, including mixtures prepared in this laboratory using a coprecipitation procedure, have been obtained. Much of the work during year 02 consisted of

  14. HIGH EFFICIENCY DESULFURIZATION OF SYNTHESIS GAS

    SciTech Connect

    Kwang-Bok Yi; Elizabeth J. Podlaha; Douglas P. Harrison

    2002-11-01

    Mixed metal oxides containing CeO{sub 2} and ZrO{sub 2} are being studied as high temperature desulfurization sorbents capable of achieving the DOE Vision 21 target of 1 ppmv or less H{sub 2}S. The research is justified by recent results in this laboratory that showed that reduced CeO{sub 2}, designated CeO{sub n} (1.5 < n < 2.0), is capable of achieving the 1 ppmv target in highly reducing gas atmospheres. The addition of ZrO{sub 2} has improved the performance of oxidation catalysts and three-way automotive catalysts containing CeO{sub 2}, and should have similar beneficial effects on CeO{sub 2} desulfurization sorbents. An electrochemical method for synthesizing CeO{sub 2}-ZrO{sub 2} was developed and the products were characterized by XRD and TEM during year 01. Nanocrystalline particles having a diameter of about 5 nm and containing from approximately 10 mol% to 80 mol% ZrO{sub 2} were prepared. XRD showed the product to be a solid solution at low ZrO{sub 2} contents with a separate ZrO{sub 2} phase emerging at higher ZrO{sub 2} levels. Unfortunately, the quantity of CeO{sub 2}-ZrO{sub 2} that could be prepared electrochemically was too small to permit full testing in our desulfurization reactor. Also during year 01 a laboratory-scale fixed-bed reactor was constructed for desulfurization testing. All components of the reactor and analytical systems that may be exposed to low concentrations of H{sub 2}S are constructed of quartz, Teflon, or silcosteel. Reactor product gas composition as a function of time is determined using a Varian 3800 gas chromatograph equipped with a pulsed flame photometric detector (PFPD) for measuring low H{sub 2}S concentrations ({approx}< 10 ppmv) and a thermal conductivity detector (TCD) for higher concentrations of H{sub 2}S. Larger quantities of CeO{sub 2}-ZrO{sub 2} mixtures from other sources, including mixtures prepared in this laboratory using a coprecipitation procedure, have been obtained. Characterization and desulfurization

  15. Energy efficient engine high-pressure turbine detailed design report

    NASA Technical Reports Server (NTRS)

    Thulin, R. D.; Howe, D. C.; Singer, I. D.

    1982-01-01

    The energy efficient engine high-pressure turbine is a single stage system based on technology advancements in the areas of aerodynamics, structures and materials to achieve high performance, low operating economics and durability commensurate with commercial service requirements. Low loss performance features combined with a low through-flow velocity approach results in a predicted efficiency of 88.8 for a flight propulsion system. Turbine airfoil durability goals are achieved through the use of advanced high-strength and high-temperature capability single crystal materials and effective cooling management. Overall, this design reflects a considerable extension in turbine technology that is applicable to future, energy efficient gas-turbine engines.

  16. Summary of high-efficiency solar-cell research

    NASA Technical Reports Server (NTRS)

    Kachare, R.

    1985-01-01

    High-efficiency solar-cell activities supporting efforts to achieve the DOE Five-Year Plan goals are summarized. Specific objectives are to identify and resolve key generic problems that limit cell efficiency to below theoretically predicted values and to design and fabricate cells having efficiences equal to or greater than 20% (AM1.5). Theoretical curves for various p-n junction cells were shown. The effects of practical barriers on cell efficiency was depicted along with the modeling parameters. Cell design parameters used in the analyses were described. The usefulness and present limitations of the existing modeling capabilities were presented. The historical evolution of the efficiencies of cells made from web and edge-defined film-fed growth (EFG) silicon ribbons were also described. The status of contemporary higher-efficiency technical capabilities and future activities to raise efficiencies were stated.

  17. On the Ability of Ascends to Constrain Fossil Fuel, Ocean and High Latitude Emissions: Flux Estimation Experiments

    NASA Astrophysics Data System (ADS)

    Crowell, S.; Kawa, S. R.; Hammerling, D.; Moore, B., III; Rayner, P. J.

    2014-12-01

    In Hammerling et al., 2014 (H14) the authors demonstrated a geostatistical method for mapping satellite estimates of column integrated CO2 mixing ratio, denoted XCO2, that incorporates the spatial variability in satellite-measured XCO2 as well as measurement precision. The goal of the study was to determine whether the Active Sensing of CO2 over Nights, Days and Seasons (ASCENDS) mission would be able to detect changes in XCO2 given changes in the underlying fluxes for different levels of instrument precision. Three scenarios were proposed: a flux-neutral shift in fossil fuel emissions from Europe to China (shown in the figure); a permafrost melting event; interannual variability in the Southern Oceans. The conclusions of H14 were modest but favorable for detectability in each case by ASCENDS given enough observations and sufficient precision. These signal detection experiments suggest that ASCENDS observations, together with a chemical transport model and data assimilation methodology, would be sufficient to provide quality estimates of the underlying surface fluxes, so long as the ASCENDS observations are precise enough. In this work, we present results that bridge the gap between the previous signal detection work by [Hammerling et al., 2014] and the ability of transport models to recover flux perturbations from ASCENDS observations utilizing the TM5-4DVAR data assimilation system. In particular, we will explore the space of model and observational uncertainties that will yield useful scientific information in each of the flux perturbation scenarios. This work will give a sense of the ability of ASCENDS to answer key questions about some of the foremost questions in carbon cycle science today. References: Hammerling, D., Kawa, S., Schaefer, K., and Michalak, A. (2014). Detectability of CO2 flux signals by a space-based lidar mission. Submitted.

  18. High-efficiency backlight module with two guiding modes.

    PubMed

    Li, Chang-Yi; Pan, Jui-Wen

    2014-03-10

    We propose a design for a high-efficiency backlight module that does not require a brightness enhancement film (BEF). With the high-efficiency backlight module it is possible to achieve almost the same half-luminance angle as a conventional edge-lit backlight module can achieve. The backlight system is comprised of a crisscross light guide plate (LGP) and one diffuser sheet. The crisscross LGP is composed of a LGP and optically patterned film (OPF). The backlight module allows light to be extracted through the direct guiding mode and top guiding mode, respectively. We controlled arrangement of the microstructures to increase the optical efficiency and the uniformity by two modes. Compared to the conventional edge-lit backlight module, there is a two-fold improvement in both the total optical efficiency and on-axis luminance with the high-efficiency backlight module.

  19. Development of an Improved High Efficiency Thin Solar Cell

    NASA Technical Reports Server (NTRS)

    Lindmayer, J.; Wrigley, C.; Storti, G.

    1979-01-01

    High efficiency cells (up to 14 AMO at 25 C)were fabricated from 10 - 15 ohm-cm silicon by using screen printed aluminum paste as the alloy source for the production of back surface fields. Thick consistency pastes that have been cured prior to a short heat treatment at 850 C were most effective in achieving these efficiency levels.

  20. Space solar cells: High efficiency and radiation damage

    NASA Technical Reports Server (NTRS)

    Brandhorst, H., Jr.; Bernatowicz, D. T.

    1980-01-01

    The progress and status of efforts to increase the end-of-life efficiency of solar cells for space use is assessed. High efficiency silicon solar cells, silicon solar cell radiation damage, GaAs solar cell performance and radiation damage and 30 percent devices are discussed.

  1. 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…

  2. High efficiency hydrocarbon-free resonance transition potassium laser

    NASA Astrophysics Data System (ADS)

    Zweiback, Jason; Hager, Gordon; Krupke, William F.

    2009-05-01

    We experimentally demonstrate a high efficiency potassium laser using a 0.15 nm bandwidth alexandrite laser as the pump source. The laser uses naturally occurring helium as the buffer gas. We achieve a 64% slope efficiency and a 57% optical to optical conversion. A pulsed laser model shows good agreement with the data.

  3. Radiochemical dates obtained by alpha spectrometry on fossil mollusk shell from the 5e Atlantic shoreline of the High Atlas, Morocco.

    PubMed

    Choukri, A; Hakam, O-K; Reyss, J-L; Plaziat, J-C

    2007-08-01

    The reported radiochemical results obtained on 77 samples collected from Moroccan fossil beaches assumed to be deposited during the above present sea-level high stands corresponding to 5e climatic stage, and on 12 present and Holocene samples, are discussed in order to judge the age validity. Contrary to the Holocene shells where (238)U contents are low and (234)U/(238)U are in agreement with sea-water ratio, the 5e results vary considerably irrespective of species and calcite content of samples. Because of the open-system possibility, the (230)Th/(234)U ages based on shell samples should be interpreted as minima for any studied shoreline discussed in the light of geological data and several shells analyses.

  4. High efficiency interdigitated back contact silicon solar cells

    NASA Astrophysics Data System (ADS)

    Verlinden, P.; van de Wiele, F.; Stehelin, G.; Floret, F.; David, J. P.

    Interdigitated back contact (IBC) silicon solar cells with 25.6 percent efficiency at 10 W/sq cm and 24.4 percent at 30 W/ sq cm were fabricated. The authors report on the technological process, which produces a high effective carrier lifetime in the bulk (780 microsec), and on the characterization of the cells. The front side of these cells is textured and has an efficient polka-dot floating tandem junction. IBC and point-contact (PC) cells are fabricated on the same substrate and their efficiencies are compared. The possiblity of reaching 29 percent efficiency at 300X is shown.

  5. High efficiency, low cost buried contact silicon solar cells

    SciTech Connect

    Honsberg, C.B.; Wenham, S.R.; Ebong, A.

    1994-12-31

    The buried contact (BC) technology has demonstrated both an efficiency and cost advantage over conventional screen printed solar cells. New BC structures, in particular the double sided (DS) BC cell, allow further improvements in cost and efficiency. Improvements in efficiency arise through improved rear surface passivation. Experimental results from DSBC cells using various passivation methods demonstrate that a floating junction (FJ) passivates as well as passivation schemes used with high efficiency cells. 2D analysis and experimental results both show localized defects have prevented FJ passivation from achieving its potential and that optimization of the rear doping or by bifacial operation can improve performance.

  6. High efficiency solar cell research for space applications

    NASA Technical Reports Server (NTRS)

    Flood, D. J.

    1985-01-01

    A review is given of NASA photovoltaic research with emphasis on the activities of the Lewis Research Center. High efficiency solar cell research is discussed, as well as solar arrays, multi-junction cell bandgaps, and plasmon coupling.

  7. III-V High-Efficiency Multijunction Photovoltaics (Fact Sheet)

    SciTech Connect

    Not Available

    2011-06-01

    Capabilities fact sheet that includes scope, core competencies and capabilities, and contact/web information for III-V High-Efficiency Multijunction Photovoltaics at the National Center for Photovoltaics.

  8. 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.

    1984-01-01

    The development of high efficiency solar cells on a silicon web is discussed. Heat treatment effects on web quality; the influence of twin plane lamellae, trace impurities and stress on minority carrier lifetime; and the fabrication of cells are discussed.

  9. Infrared Spectra of Fossils,

    DTIC Science & Technology

    fossil’s surface is accessible to the analyzing beams. The technique is potentially valuable for the examination of special samples of palaeontological and archaeological interest. Keywords include: Photothermal effect.

  10. Natural Product Molecular Fossils.

    PubMed

    Falk, Heinz; Wolkenstein, Klaus

    2017-01-01

    The natural products synthesized by organisms that were living a long time ago gave rise to their molecular fossils. These can consist of either the original unchanged compounds or they may undergo peripheral transformations in which their skeletons remain intact. In cases when molecular fossils can be traced to their organismic source, they are termed "geological biomarkers".This contribution describes apolar and polar molecular fossils and, in particular biomarkers, along the lines usually followed in organic chemistry textbooks, and points to their bioprecursors when available. Thus, the apolar compounds are divided in linear and branched alkanes followed by alicyclic compounds and aromatic and heterocyclic molecules, and, in particular, the geoporphyrins. The polar molecular fossils contain as functional groups or constituent units ethers, alcohols, phenols, carbonyl groups, flavonoids, quinones, and acids, or are polymers like kerogen, amber, melanin, proteins, or nucleic acids. The final sections discuss the methodology used and the fundamental processes encountered by the biomolecules described, including diagenesis, catagenesis, and metagenesis.

  11. Recent developments in high-efficiency PV cells

    SciTech Connect

    Deb, S.

    2000-05-22

    Enormous progress has been made in recent years on a number of photovoltaic (PV) materials and devices in terms of conversion efficiencies. Ultrahigh-efficiency (>30{percent}) PV cells have been fabricated from gallium arsenide (GaAs) and its ternary alloys such as gallium indium phosphide (GaInP{sub 2}). The high-efficiency GaAs-based solar cells are being produced on a commercial scale, particularly for space applications. Efficiencies in the range of 18{percent} to 24{percent} have been achieved in traditional silicon-based devices fabricated from both multicrystalline and single-crystal materials. Major advances in efficiency have also been made on various thin-film solar cells based on amorphous silicon (aSi:H), copper gallium indium diselenide (CIGS), and cadmium telluride materials. This paper gives a brief overview of the recent progress in PV cell efficiencies based on these materials and devices.

  12. Global climate change: Mitigation opportunities high efficiency large chiller technology

    SciTech Connect

    Stanga, M.V.

    1997-12-31

    This paper, comprised of presentation viewgraphs, examines the impact of high efficiency large chiller technology on world electricity consumption and carbon dioxide emissions. Background data are summarized, and sample calculations are presented. Calculations show that presently available high energy efficiency chiller technology has the ability to substantially reduce energy consumption from large chillers. If this technology is widely implemented on a global basis, it could reduce carbon dioxide emissions by 65 million tons by 2010.

  13. Evolution: Fossil Ears and Underwater Sonar.

    PubMed

    Lambert, Olivier

    2016-08-22

    A key innovation in the history of whales was the evolution of a sonar system together with high-frequency hearing. Fossils of an archaic toothed whale's inner ear bones provide clues for a stepwise emergence of underwater echolocation ability.

  14. 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.

  15. [Raman spectra of fossil dinosaurs from different regions].

    PubMed

    Yang, Qun; Wang, Yi-lin

    2007-12-01

    Raman microscopic spectra in the higher wave number region were obtained from 7 fossil dinosaurs specimens from different regions. The specimens of fossil dinosaurs are different parts of bone. The Raman spectra of fossil dinosaurs indicate the high similarity among peak positions of different fossil dinosaurs; but important differences exist in the spectral peak figures. In the wave number region of 1000-1800 cm(-1) the Raman spectra of the same bone part fossils from different regions are very similar, example similarities between spectra of Lufeing backbone head and Yua nmou backbone head; Lufeng limb bone and Wuding limb bone. There are relations between the same bone part spectra of different fossil dinosaurs. The characteristic does not relate to regions. Raman spectra of fossil dinosaurs cannot be used to distinguish fossil source, although the part of bone can be used as an indicator to narrow the range of possible geographical origins.

  16. 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.

  17. Nano- and Microstructure Engineering: An Effective Method for Creating High Efficiency Magnesium Silicide Based Thermoelectrics.

    PubMed

    Farahi, Nader; Prabhudev, Sagar; Botton, Gianluigi A; Salvador, James R; Kleinke, Holger

    2016-12-21

    Considering the effect of CO2 emission together with the depletion of fossil fuel resources on future generations, industries in particular the transportation sector are in deep need of a viable solution to follow the environmental regulation to limit the CO2 emission. Thermoelectrics may be a practical choice for recovering the waste heat, provided their conversion energy can be improved. Here, the high temperature thermoelectric properties of high purity Bi doped Mg2(Si,Sn) are presented. The samples Mg2Si1-x-ySnxBiy with x(Sn) ≥ 0.6 and y(Bi) ≥ 0.03 exhibited electrical conductivities and Seebeck coefficients of approximately 1000 Ω(-1) cm(-1) and -200 μV K(-1) at 773 K, respectively, attributable to a combination of band convergence and microstructure engineering through ball mill processing. In addition to the high electrical conductivity and Seebeck coefficient, the thermal conductivity of the solid solutions reached values below 2.5 W m(-1) K(-1) due to highly efficient phonon scattering from mass fluctuation and grain boundary effects. These properties combined for zT values of 1.4 at 773 K with an average zT of 0.9 between 400 and 773 K. The transport properties were both highly reproducible across several measurement systems and were stable with thermal cycling.

  18. Phenomena and Performance of High-Efficiency Split Spectrum Photovoltaics

    NASA Astrophysics Data System (ADS)

    Downs, Chandler

    High-efficiency photovoltaics are one of the most promising technologies for supplying sustainable energy in the near future. These technologies allow for high energy conversion efficiencies and long system lifetimes, which is becoming an increasingly profitable power generation option. One high-efficiency photovoltaic technology gaining increasing attention recent years is that of split-spectrum photovoltaics. This technology divides the incident solar spectrum on the basis of wavelength, directing each portion of the spectrum to a different cell where the light can be utilized most efficiently. In this dissertation, a number of aspects of high-efficiency photovoltaics, most notably split-spectrum photovoltaics, are examined. First, the ideal bandgap placements of the subcells of a split-spectrum photovoltaic system are calculated, specifically determined with an eye towards practical fabrication of the cells. Two viable designs are determined which improve theoretical absolute conversion efficiency by 4-5%. Next, those systems are simulated using the TCAD Sentaurus software package to project conversion efficiencies and determine additional device specifications (doping levels, layer thicknesses, etc.). These cells show comparable conversion efficiencies to high performing, full-spectrum multijunction photovoltaics in fabrication today. In the last section, a theoretical examination of semiconductor performance under high optical concentration is performed, including the prediction and characterization of various phenomena in those devices. This work aims to improve the understanding of the performance of high concentration photovoltaics, most notably split-spectrum photovoltaics. This understanding will aid in the advancement of this technology as a widespread, sustainable energy source for use worldwide, reducing greenhouse emissions and providing cheap, clean energy.

  19. Highly efficient carrier multiplication in PbS nanosheets

    PubMed Central

    Aerts, Michiel; Bielewicz, Thomas; Klinke, Christian; Grozema, Ferdinand C.; Houtepen, Arjan J.; Schins, Juleon M.; Siebbeles, Laurens D. A.

    2014-01-01

    Semiconductor nanocrystals are promising for use in cheap and highly efficient solar cells. A high efficiency can be achieved by carrier multiplication (CM), which yields multiple electron-hole pairs for a single absorbed photon. Lead chalcogenide nanocrystals are of specific interest, since their band gap can be tuned to be optimal to exploit CM in solar cells. Interestingly, for a given photon energy CM is more efficient in bulk PbS and PbSe, which has been attributed to the higher density of states. Unfortunately, these bulk materials are not useful for solar cells due to their low band gap. Here we demonstrate that two-dimensional PbS nanosheets combine the band gap of a confined system with the high CM efficiency of bulk. Interestingly, in thin PbS nanosheets virtually the entire excess photon energy above the CM threshold is used for CM, in contrast to quantum dots, nanorods and bulk lead chalcogenide materials. PMID:24781188

  20. Research on stable, high-efficiency, amorphous silicon multijunction modules

    SciTech Connect

    Catalano, A.; Bennett, M.; Chen, L.; D'Aiello, R.; Fieselmann, B.; Li, Y.; Newton, J.; Podlesny, R.; Yang, L. . Thin Film Div.)

    1992-08-01

    This report describes work to demonstrate a multijunction module with a stabilized'' efficiency (600 h, 50{degrees}C, AM1.5) of 10.5%. Triple-junction devices and modules using a-Si:H alloys with carbon and germanium were developed to meet program goals. ZnO was used to provide a high optical transmission front contact. Proof of concept was obtained for several important advances deemed to be important for obtaining high (12.5%) stabilized efficiency. They were (1) stable, high-quality a-SiC:H devices and (2) high-transmission, textured ZnO. Although these developments were not scaled up and included in modules, triple-junction module efficiencies as high as 10.85% were demonstrated. NREL measured 9.62% and 9.00% indoors and outdoors, respectively. The modules are expected to lose no more than 20% of their initial performance. 28 refs.

  1. High surface area electrode for high efficient microbial electrosynthesis

    NASA Astrophysics Data System (ADS)

    Nie, Huarong; Cui, Mengmeng; Lu, Haiyun; Zhang, Tian; Russell, Thomas; Lovley, Derek

    2012-02-01

    Microbial electrosynthesis, a process in which microorganisms directly accept electrons from an electrode to convert carbon dioxide and water into multi carbon organic compounds, affords a novel route for the generation of valuable products from electricity or even wastewater. The surface area of the electrode is critical for high production. A biocompatible, highly conductive, three-dimensional cathode was fabricated from a carbon nanotube textile composite to support the microorganism to produce acetate from carbon dioxide. The high surface area and macroscale porous structure of the intertwined CNT coated textile ?bers provides easy microbe access. The production of acetate using this cathode is 5 fold larger than that using a planar graphite electrode with the same volume. Nickel-nanowire-modified carbon electrodes, fabricated by microwave welding, increased the surface area greatly, were able to absorb more bacteria and showed a 1.5 fold increase in performance

  2. Fossil Simulation in the Classroom

    ERIC Educational Resources Information Center

    Hoehn, Robert G.

    1977-01-01

    Describes classroom science demonstrations and experiments that simulate the process of fossil formation. Lists materials, procedures and suggestions for successful activities. Includes ten student activities (coral fossils, leaf fossils, leaf scars, carbonization, etc.). Describes a fossil game in which students work in pairs. (CS)

  3. Bayesian phylogenetic estimation of fossil ages

    PubMed Central

    Drummond, Alexei J.; Stadler, Tanja

    2016-01-01

    Recent advances have allowed for both morphological fossil evidence and molecular sequences to be integrated into a single combined inference of divergence dates under the rule of Bayesian probability. In particular, the fossilized birth–death tree prior and the Lewis-Mk model of discrete morphological evolution allow for the estimation of both divergence times and phylogenetic relationships between fossil and extant taxa. We exploit this statistical framework to investigate the internal consistency of these models by producing phylogenetic estimates of the age of each fossil in turn, within two rich and well-characterized datasets of fossil and extant species (penguins and canids). We find that the estimation accuracy of fossil ages is generally high with credible intervals seldom excluding the true age and median relative error in the two datasets of 5.7% and 13.2%, respectively. The median relative standard error (RSD) was 9.2% and 7.2%, respectively, suggesting good precision, although with some outliers. In fact, in the two datasets we analyse, the phylogenetic estimate of fossil age is on average less than 2 Myr from the mid-point age of the geological strata from which it was excavated. The high level of internal consistency found in our analyses suggests that the Bayesian statistical model employed is an adequate fit for both the geological and morphological data, and provides evidence from real data that the framework used can accurately model the evolution of discrete morphological traits coded from fossil and extant taxa. We anticipate that this approach will have diverse applications beyond divergence time dating, including dating fossils that are temporally unconstrained, testing of the ‘morphological clock', and for uncovering potential model misspecification and/or data errors when controversial phylogenetic hypotheses are obtained based on combined divergence dating analyses. This article is part of the themed issue ‘Dating species divergences

  4. High Efficiency Adsorption Chillers: High Efficiency Adsorption Cooling Using Metal Organic Heat Carriers

    SciTech Connect

    2010-10-01

    BEETIT Project: PNNL is incorporating significant improvements in materials that adsorb liquids or gases to design more efficient adsorption chillers. An adsorption chiller is a type of air conditioner that is powered by heat, solar or waste heat, or combustion of natural gas. Unlike typical chillers, this type has few moving parts and uses almost no electricity to operate. PNNL is designing adsorbent materials at the molecular level with at least 3 times higher refrigerant capacity and up to 20 times faster kinetics than adsorbents used in current chillers. By using the new adsorbent, PNNL is able to create a chiller that is significantly smaller, has twice the energy efficiency, and lower costs for materials and assembly time compared to conventional adsorption chillers.

  5. A highly efficient cocaine detoxifying enzyme obtained by computational design

    PubMed Central

    Zheng, Fang; Xue, Liu; Hou, Shurong; Liu, Junjun; Zhan, Max; Yang, Wenchao; Zhan, Chang-Guo

    2014-01-01

    Compared to naturally occurring enzymes, computationally designed enzymes are usually much less efficient, with their catalytic activities being more than six orders of magnitude below the diffusion limit. Here we use a two-step computational design approach, combined with experimental work, to design a highly efficient cocaine hydrolising enzyme. We engineer E30-6 from human butyrylcholinesterase (BChE), which is specific for cocaine hydrolysis, and obtain a much higher catalytic efficiency for cocaine conversion than for conversion of the natural BChE substrate, acetylcholine (ACh). The catalytic efficiency of E30-6 for cocaine hydrolysis is comparable to that of the most efficient known naturally-occurring hydrolytic enzyme, acetylcholinesterase, the catalytic activity of which approaches the diffusion limit. We further show that E30-6 can protect mice from a subsequently administered lethal dose of cocaine, suggesting the enzyme may have therapeutic potential in the setting of cocaine detoxification or cocaine abuse. PMID:24643289

  6. 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.

  7. Selective Preservation of Fossil Ghost Fish

    NASA Astrophysics Data System (ADS)

    Meacham, Amanda

    2016-04-01

    A unique type of fossil fish preservation has been discovered in the Angelo Member (Fossil Lake) of the Green River Formation. The Angelo Member is a predominately evaporative deposit dominated by dolomite, but contains facies of fossiliferous laminated calcimicrite. Fossil fish occurring in two beds conspicuously lack bones. Fish in the lower bed are only preserved as organic material, including skin, pigments, and eyes. Fish in the upper bed have three-dimensional etching where bones once existed but also contain skin, pigments, and eyes. The top third of the upper bed often contains calcite crystals that are pseudomorphs after trona and possibly halite. Preliminary mineralogical analysis and mapping of evaporate facies suggests that this unique preservation may be related to lake geochemical conditions, such as high pH and alkalinity. To our knowledge, this is the first time this type of preservation has been observed and studied. Fossils and sediments within these beds are being studied both vertically and laterally through the one-meter thick sequence containing the fossil fish using XRD, isotopic, SEM, thin section, and total organic carbon analysis. Nine quarries, 0.5-1 meter square, were excavated for both fossils and rock samples along with 17 additional rock sample locations across an approximately 25-kilometer square region. This investigation has the capability of reconstructing the paleoenvironment and lake chemistry of Fossil Lake during the deposition of the "ghost-fish" beds and solving the mystery of the "missing bones" and the unusual process of preservation.

  8. 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.

  9. High efficiency upconversion nanophosphors for high-contrast bioimaging.

    PubMed

    Alkahtani, Masfer H; Alghannam, Fahad S; Sanchez, Carlos; Gomes, Carmen L; Liang, Hong; Hemmer, Philip R

    2016-12-02

    Upconversion nanoparticles (UCNPs) are of interest because they allow suppression of tissue autofluorescence and are therefore visible deep inside biological tissue. Compared to upconversion dyes, UCNPs have a lower pump intensity threshold, better photostability, and less toxicity. Recently, YVO4: Er(+3), Yb(+3) nanoparticles were shown to exhibit strong up-conversion luminescence with a relatively low 10 kW cm(-2) excitation intensity even in water, which makes them excellent bio-imaging candidates. Herein, we investigate their use as internal probes in insects by injecting YVO4 : Er(+3), Yb(+3) nanoparticles into fire ants as a biological model, and obtain 2D optical images with 980 nm illumination. High-contrast images with high signal-to-noise ratio are observed by detecting the up-conversion fluorescence as the excitation laser is scanned.

  10. High efficiency upconversion nanophosphors for high-contrast bioimaging

    NASA Astrophysics Data System (ADS)

    Alkahtani, Masfer H.; Alghannam, Fahad S.; Sanchez, Carlos; Gomes, Carmen L.; Liang, Hong; Hemmer, Philip R.

    2016-12-01

    Upconversion nanoparticles (UCNPs) are of interest because they allow suppression of tissue autofluorescence and are therefore visible deep inside biological tissue. Compared to upconversion dyes, UCNPs have a lower pump intensity threshold, better photostability, and less toxicity. Recently, YVO4: Er+3, Yb+3 nanoparticles were shown to exhibit strong up-conversion luminescence with a relatively low 10 kW cm-2 excitation intensity even in water, which makes them excellent bio-imaging candidates. Herein, we investigate their use as internal probes in insects by injecting YVO4 : Er+3, Yb+3 nanoparticles into fire ants as a biological model, and obtain 2D optical images with 980 nm illumination. High-contrast images with high signal-to-noise ratio are observed by detecting the up-conversion fluorescence as the excitation laser is scanned.

  11. 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

  12. Fossil group origins. VII. Galaxy substructures in fossil systems

    NASA Astrophysics Data System (ADS)

    Zarattini, S.; Girardi, M.; Aguerri, J. A. L.; Boschin, W.; Barrena, R.; del Burgo, C.; Castro-Rodriguez, N.; Corsini, E. M.; D'Onghia, E.; Kundert, A.; Méndez-Abreu, J.; Sánchez-Janssen, R.

    2016-02-01

    Context. Fossil groups (FG) are expected to be the final product of galaxy merging within galaxy groups. In simulations, they are predicted to assemble their mass at high redshift. This early formation allows for the innermost M∗ galaxies to merge into a massive central galaxy. Then, they are expected to maintain their fossil status because of the few interactions with the large-scale structure. In this context, the magnitude gap between the two brightest galaxies of the system is considered a good indicator of its dynamical status. As a consequence, the systems with the largest gaps should be dynamically relaxed. Aims: In order to examine the dynamical status of these systems, we systematically analyze, for the first time, the presence of galaxy substructures in a sample of 12 spectroscopically-confirmed fossil systems with redshift z ≤ 0.25. Methods: We apply a number of tests to investigate the substructure in fossil systems in the two-dimensional space of projected positions out to R200. Moreover, for a subsample of five systems with at least 30 spectroscopically-confirmed members we also analyze the substructure in the velocity and in the three-dimensional velocity-position spaces. Additionally, we look for signs of recent mergers in the regions around the central galaxies. Results: We find that an important fraction of fossil systems show substructure. The fraction depends critically on the adopted test, since each test is more sensitive to a particular type of substructure. Conclusions: Our interpretation of the results is that fossil systems are not, in general, as relaxed as expected from simulations. Our sample of 12 spectroscopically-confirmed fossil systems need to be extended to compute an accurate fraction, but our conclusion is that this fraction is similar to the fraction of substructure detected in nonfossil clusters. This result points out that the magnitude gap alone is not a good indicator of the dynamical status of a system. However, the

  13. High Power Klystrons for Efficient Reliable High Power Amplifiers.

    DTIC Science & Technology

    1980-11-01

    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...photographs, operating/ maintanance instructions, layout drawings/schematics and the purchase specification are included, in the above order, in

  14. 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.

  15. High-efficiency beam bending using graded photonic crystals.

    PubMed

    Oner, B B; Turduev, M; Kurt, H

    2013-05-15

    We explore beam-bending properties of graded index (GRIN) waveguide with hyperbolic secant profile. The transmission efficiency and bandwidth features are extracted for GRIN photonic crystal (PC) media composed of dielectric rods. Light guiding performance of the GRIN PC medium is analyzed for 90° and 180° waveguide bends. The finite-difference time-domain method is deployed to investigate the performance of the designed GRIN waveguides. By the help of proposed photonic configuration, bending of light is achieved with a high efficiency within a broad bandwidth, which promotes the use of GRIN PC structures for efficient light-bending purposes.

  16. 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.

  17. Development of an Improved High Efficiency Thin Silicon Solar Cell

    NASA Technical Reports Server (NTRS)

    Storti, G.; Wrigley, C.

    1979-01-01

    Breakage and front contact failure in high efficiency, textured ultrathin cells was reduced as a consequence of the introduction of process modifications. In a small production run, over one hundred ultrathin cells, having an average AMO efficiency of 13%, were fabricated from 10-25 ohm cm silicon. An in-house aluminum paste for back surface field formation was developed that resulted in cell efficiencies equivalent to those from commercial pastes. The quality of the back surface field was found to be dependent on the orientation of the silicon slice during alloying.

  18. High efficiency cw laser-pumped tunable alexandrite laser

    SciTech Connect

    Lai, S.T.; Shand, M.L.

    1983-10-01

    High efficiency cw alexandrite laser operation has been achieved. With longitudinal pumping by a krypton laser in a nearly concentric cavity, a 51% output power slope efficiency has been measured. Including the transmission at the input coupler mirror, a quantum yield of 85% has been attained above threshold. Tunability from 726 to 802 nm has also been demonstrated. The low loss and good thermal properties make alexandrite ideal for cw laser operation.

  19. Multiple Exciton Generation for Highly Efficient Solar Cells

    NASA Astrophysics Data System (ADS)

    Nozik, Arthur

    2007-03-01

    In order to utilize solar power for the production of electricity and fuel on a massive scale, it will be necessary to develop solar photon conversion systems that have an appropriate combination of high efficiency and low capital cost (/m^2). One new potential approach to high solar cell efficiency is to utilize the unique properties of semiconductor quantum dot nanostructures to control the relaxation dynamics of photogenerated carriers to produce either enhanced photocurrent through efficient multiple exciton generation (MEG) or enhanced photopotential through hot electron transport and transfer processes. To achieve these desirable effects it is necessary to understand and control the dynamics of electron relaxation, cooling, multiple exciton generation , transport, and interfacial electron transfer of the photogenerated carriers with fs to ns time resolution. We have been studying these fundamental dynamics in bulk and nanoscale semiconductors (quantum dots, quantum wires, and quantum wells) using femtosecond transient absorption, photoluminescence, and THz spectroscopy. This work will be summarized and recent advances in creating multiple excitons from a single photon will be discussed, including a unique model to explain efficient MEG based on the coherent superposition of multiple excitonic states. Various possible configurations for quantum dot solar cells that could produce ultra-high conversion efficiencies for the production of electricity, as well as for producing solar fuels (for example, hydrogen from water splitting), will be discussed, along with associated thermodynamic calculations that show the increase in the maximum theoretical gain in solar photon conversion efficiency for both electricity and fuel production.

  20. High Efficient Synthesis of Iron-based Superconductors

    NASA Astrophysics Data System (ADS)

    Fang, Ai-Hua; Huang, Fu-Qiang; Xie, Xiao-Ming; Jiang, Mian-Heng

    We have performed systematic investigations aimed at high efficient synthesis of the 1111 family iron-based superconductors. By using meta-stable reactive starting materials of LnAs and FeO, assisted by mechanical alloying and fast heating, high purity samples with Tconset greater than 50K can be made with sintering temperatures between 1433K-1073K, and sintering time from 20 min to 40 h. High purity phase with sintering temperature as low as 973K was demonstrated successfully although Tconset fall below 50K and weak grain boundary suppressed greatly the zero resistance temperature. Ultra fast microwave sintering brings the sintering time further down to 5 min. Samples prepared by the above high efficient methods typically posses submicron grain and very high upper critical field, indicating very high pinning power. Besides offering cost advantages, the developed methods may play important roles in the exploit of novel superconductors.

  1. 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

  2. Heat transparent high intensity high efficiency solar cell

    NASA Technical Reports Server (NTRS)

    Evans, J. C., Jr. (Inventor)

    1982-01-01

    An improved solar cell design is described. A surface of each solar cell has a plurality of grooves. Each groove has a vertical face and a slanted face that is covered by a reflecting metal. Light rays are reflected from the slanted face through the vertical face where they traverse a photovoltaic junction. As the light rays travel to the slanted face of an adjacent groove, they again traverse the junction. The underside of the reflecting coating directs the light rays toward the opposite surface of solar cell as they traverse the junction again. When the light rays travel through the solar cell and reach the saw toothed grooves on the under side, the process of reflection and repeatedly traversing the junction again takes place. The light rays ultimately emerge from the solar cell. These solar cells are particularly useful at very high levels of insolation because the infrared or heat radiation passes through the cells without being appreciably absorbed to heat the cell.

  3. HIGH EFFICIENCY GENERATION OF HYDROGEN FUELS USING NUCLEAR POWER FINAL RECHNICAL REPORT FOR THE PERIOD AUGUST 1, 1999 THROUGH SEPTEMBER 30, 2002 REV. 1

    SciTech Connect

    BROWN,LC; BESENBRUCH,GE; LENTSCH, RD; SCHULTZ,KR; FUNK,JF; PICKARD,PS; MARSHALL,AC; SHOWALTER,SK

    2003-12-01

    OAK-B135 Combustion of fossil fuels, used to power transportation, generate electricity, heat homes and fuel industry provides 86% of the world's energy [1-1,1-2]. Drawbacks to fossil fuel utilization include limited supply, pollution, and carbon dioxide emissions. Carbon dioxide emissions, thought to be responsible for global warming, are now the subject of international treaties [1-3,1-4]. Together, these drawbacks argue for the replacement of fossil fuels with a less-polluting potentially renewable primary energy such as nuclear energy. Conventional nuclear plants readily generate electric power but fossil fuels are firmly entrenched in the transportation sector. Hydrogen is an environmentally attractive transportation fuel that has the potential to displace fossil fuels. Hydrogen will be particularly advantageous when coupled with fuel cells. Fuel cells have higher efficiency than conventional battery/internal combustion engine combinations and do not produce nitrogen oxides during low-temperature operation. Contemporary hydrogen production is primarily based on fossil fuels and most specifically on natural gas. When hydrogen is produced using energy derived from fossil fuels, there is little or no environmental advantage. There is currently no large scale, cost-effective, environmentally attractive hydrogen production process available for commercialization, nor has such a process been identified. The objective of this work is to find an economically feasible process for the production of hydrogen, by nuclear means, using an advanced high-temperature nuclear reactor as the primary energy source. Hydrogen production by thermochemical water-splitting (Appendix A), a chemical process that accomplishes the decomposition of water into hydrogen and oxygen using only heat or, in the case of a hybrid thermochemical process, by a combination of heat and electrolysis, could meet these goals. Hydrogen produced from fossil fuels has trace contaminants (primarily carbon

  4. Low Cost, High Efficiency, High Pressure Hydrogen Storage

    SciTech Connect

    Mark Leavitt

    2010-03-31

    A technical and design evaluation was carried out to meet DOE hydrogen fuel targets for 2010. These targets consisted of a system gravimetric capacity of 2.0 kWh/kg, a system volumetric capacity of 1.5 kWh/L and a system cost of $4/kWh. In compressed hydrogen storage systems, the vast majority of the weight and volume is associated with the hydrogen storage tank. In order to meet gravimetric targets for compressed hydrogen tanks, 10,000 psi carbon resin composites were used to provide the high strength required as well as low weight. For the 10,000 psi tanks, carbon fiber is the largest portion of their cost. Quantum Technologies is a tier one hydrogen system supplier for automotive companies around the world. Over the course of the program Quantum focused on development of technology to allow the compressed hydrogen storage tank to meet DOE goals. At the start of the program in 2004 Quantum was supplying systems with a specific energy of 1.1-1.6 kWh/kg, a volumetric capacity of 1.3 kWh/L and a cost of $73/kWh. Based on the inequities between DOE targets and Quantum’s then current capabilities, focus was placed first on cost reduction and second on weight reduction. Both of these were to be accomplished without reduction of the fuel system’s performance or reliability. Three distinct areas were investigated; optimization of composite structures, development of “smart tanks” that could monitor health of tank thus allowing for lower design safety factor, and the development of “Cool Fuel” technology to allow higher density gas to be stored, thus allowing smaller/lower pressure tanks that would hold the required fuel supply. The second phase of the project deals with three additional distinct tasks focusing on composite structure optimization, liner optimization, and metal.

  5. 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.

  6. 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.

  7. High efficiency silicon solar cell based on asymmetric nanowire

    PubMed Central

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

    2015-01-01

    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/cm2 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. PMID:26152914

  8. Energy Efficient Engine high pressure turbine component test performance report

    NASA Technical Reports Server (NTRS)

    Timko, L. P.

    1984-01-01

    The high pressure turbine for the General Electric Energy Efficient Engine is a two stage design of moderate loading. Results of detailed system studies led to selection of this configuration as the most appropriate in meeting the efficiency goals of the component development program. To verify the design features of the high pressure turbine, a full scale warm air turbine test rig with cooling flows simulated was run. Prior to this testing, an annular cascade test was run to select vane unguided turn for the first stage nozzle. Results of this test showed that the base configuration exceeded the lower unguided turning configuration by 0.48 percent in vane kinetic energy efficiency. The air turbine test program, consisting of extensive mapping and cooling flow variation as well as design point evaluation, demonstrated a design point efficiency level of 90.0 percent based on the thermodynamic definition. In terms of General Electric cycle definition, this efficiency was 92.5 percent. Based on this test, it is concluded that efficiency goals for the Flight Propulsion System were met.

  9. Tunable high-efficient pulsed NH3 terahertz lasers

    NASA Astrophysics Data System (ADS)

    Jiu, Zhi-Xian; Li, Qiang; Zuo, Du-Luo; Miao, Liang; Cheng, Zu-Hai

    2012-03-01

    Experimental studies on a tunable efficient high-efficient pulsed NH3 terahertz (THz) lasers pumped by TEA CO2 lasers are presented. When NH3 is pumped by the different lines with the CO2 lasers, the generation of different terahertz radiations is discussed. The lines of the CO2 lasers are 9R(08), 9P(20), 10R(14), 10R(08), and 10R(06). To improve THz laser energy and photon conversion efficiency, different higher power of the CO2 laser can effectively improve THz laser energy and photon conversion efficiency. When the 9P(20) CO2 lasers with 9.68 J and 4.12 J pump NH3, the corresponding energy conversion efficiencies are 0.28% and 0.19%, increasing by a factor of about 1.5. The generation of terahertz radiations with energy as high as 27.29 mJ and 7.73 mJ are obtained, respectively, increasing by a factor of about 3.5. Meanwhile, for 10R(14) line, the energy conversion efficiencies increase to 8.5 times and the energy of THz lasers increase to 32 times.

  10. Tunable high-efficient pulsed NH3 terahertz lasers

    NASA Astrophysics Data System (ADS)

    Jiu, Zhi-Xian; Li, Qiang; Zuo, Du-Luo; Miao, Liang; Cheng, Zu-Hai

    2011-11-01

    Experimental studies on a tunable efficient high-efficient pulsed NH3 terahertz (THz) lasers pumped by TEA CO2 lasers are presented. When NH3 is pumped by the different lines with the CO2 lasers, the generation of different terahertz radiations is discussed. The lines of the CO2 lasers are 9R(08), 9P(20), 10R(14), 10R(08), and 10R(06). To improve THz laser energy and photon conversion efficiency, different higher power of the CO2 laser can effectively improve THz laser energy and photon conversion efficiency. When the 9P(20) CO2 lasers with 9.68 J and 4.12 J pump NH3, the corresponding energy conversion efficiencies are 0.28% and 0.19%, increasing by a factor of about 1.5. The generation of terahertz radiations with energy as high as 27.29 mJ and 7.73 mJ are obtained, respectively, increasing by a factor of about 3.5. Meanwhile, for 10R(14) line, the energy conversion efficiencies increase to 8.5 times and the energy of THz lasers increase to 32 times.

  11. The fossil Oort cloud and the dynamics beyond Neptune

    NASA Astrophysics Data System (ADS)

    Saillenfest, M.; Fouchard, M.; Tommei, G.; Valsecchi, G.

    2015-10-01

    We will present here some dynamical features of the so-called fossil Oort cloud (semi major axis between 100 and 1000 AU and perihelion beyond Neptune). This region has been considered so far as totally inert, because either the planetary perturbations or the galactic tides have an extremely weak effect. However, we will show that Kozai effect can still be efficient at very high distances from the planets, and result in high amplitude oscillations of the perihelion distance on a gigayear time-scale.

  12. A high-efficiency heat-pump fan

    NASA Astrophysics Data System (ADS)

    Wright, T.; Lackey, R. S.; Veyo, S. E.

    1983-06-01

    Efforts toward development of a high-efficiency outdoor air mover for an advanced electric heat pump are documented. The design goal was to halve the outdoor air-moving electrical power. The prototype air mover at 850 rpm delivers 3070 scfm through the prototype outdoor unit with a pressure drop through the coil of 0.09 inches of water and consumes 150 watts of electrical power. The overall air-moving efficiency is estimated at about 35 percent compared with 19 percent for the conventionally-applied heat pump fan. Although this air mover will cost twice as much as the conventional heat pump air mover, this premium cost should be recoverable in less than four years through energy savings. The sound rating (SFN) for this air mover is less than 20. Means for improving fan efficiency by 5 percentage points, motor efficiency by 2.5 points, and to further quiet the fan were identified.

  13. 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.

  14. High efficiency all-polymer tandem solar cells

    PubMed Central

    Yuan, Jianyu; Gu, Jinan; Shi, Guozheng; Sun, Jianxia; Wang, Hai-Qiao; Ma, Wanli

    2016-01-01

    In this work, we have reported for the first time an efficient all-polymer tandem cell using identical sub-cells based on P2F-DO:N2200. A high power conversion efficiency (PCE) of 6.70% was achieved, which is among the highest efficiencies for all polymer solar cells and 43% larger than the PCE of single junction cell. The largely improved device performance can be mainly attributed to the enhanced absorption of tandem cell. Meanwhile, the carrier collection in device remains efficient by optimizing the recombination layer and sub-cell film thickness. Thus tandem structure can become an easy approach to effectively boost the performance of current all polymer solar cells. PMID:27226354

  15. 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.

  16. Traversing the mountaintop: world fossil fuel production to 2050.

    PubMed

    Nehring, Richard

    2009-10-27

    During the past century, fossil fuels--petroleum liquids, natural gas and coal--were the dominant source of world energy production. From 1950 to 2005, fossil fuels provided 85-93% of all energy production. All fossil fuels grew substantially during this period, their combined growth exceeding the increase in world population. This growth, however, was irregular, providing for rapidly growing per capita production from 1950 to 1980, stable per capita production from 1980 to 2000 and rising per capita production again after 2000. During the past half century, growth in fossil fuel production was essentially limited by energy demand. During the next half century, fossil fuel production will be limited primarily by the amount and characteristics of remaining fossil fuel resources. Three possible scenarios--low, medium and high--are developed for the production of each of the fossil fuels to 2050. These scenarios differ primarily by the amount of ultimate resources estimated for each fossil fuel. Total fossil fuel production will continue to grow, but only slowly for the next 15-30 years. The subsequent peak plateau will last for 10-15 years. These production peaks are robust; none of the fossil fuels, even with highly optimistic resource estimates, is projected to keep growing beyond 2050. World fossil fuel production per capita will thus begin an irreversible decline between 2020 and 2030.

  17. 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.

  18. Realization of highly efficient hexagonal boron nitride neutron detectors

    SciTech Connect

    Maity, A.; Doan, T. C.; Li, J.; Lin, J. Y.; Jiang, H. X.

    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 (>1013 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- BN 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.

  19. 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 (>1013 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- BN wasmore » 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

  20. Realization of highly efficient hexagonal boron nitride neutron detectors

    NASA Astrophysics Data System (ADS)

    Maity, A.; Doan, T. C.; Li, J.; Lin, J. Y.; Jiang, H. X.

    2016-08-01

    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 (>1013 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-BN 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.

  1. High power, high efficiency millimeter wavelength traveling wave tubes for high rate communications from deep space

    NASA Technical Reports Server (NTRS)

    Dayton, James A., Jr.

    1991-01-01

    The high-power transmitters needed for high data rate communications from deep space will require a new class of compact, high efficiency traveling wave tubes (TWT's). Many of the recent TWT developments in the microwave frequency range are generically applicable to mm wave devices, in particular much of the technology of computer aided design, cathodes, and multistage depressed collectors. However, because TWT dimensions scale approximately with wavelength, mm wave devices will be physically much smaller with inherently more stringent fabrication tolerances and sensitivity to thermal dissipation.

  2. Evaluation of a high-efficiency, filter-bank system.

    PubMed

    Martin, Stephen B; Beamer, Bryan R; Moyer, Ernest S

    2006-04-01

    National Institute for Occupational Safety and Health (NIOSH) investigators evaluated filtration efficiencies at three U.S. Postal Service (USPS) facilities. Ventilation and filtration systems (VFSs) had been installed after the 2001 bioterrorist attacks when the USPS unknowingly processed letters laden with B. anthracis spores. The new VFS units included high-efficiency particulate air (HEPA) filters and were required by USPS contract specifications to provide an overall filtration efficiency of at least 99.97% for particles between 0.3 microm and 3.0 micro m. The USPS evaluation involved a modification of methodology used to test total filtration system efficiency in agricultural tractor cab enclosures. The modified sampling strategy not only proved effective for monitoring the total filtration system component of VFS performance but also distinguished between filtration systems performing to the high USPS performance criteria and those needing repair or replacement. The results clearly showed the importance of choosing a pair of optical particle counters that have been closely matched immediately prior to testing. The modified methodology is readily adaptable to any workplace wishing to evaluate air filtration systems, including high-efficiency systems.

  3. High efficient solar tracker based on a simple shutter structure

    NASA Astrophysics Data System (ADS)

    Chen, Jin-Jia; Liu, Te-Shu; Huang, Kuang-Lung; Lin, Po-Chih

    2013-09-01

    In many photovoltaic (PV) or sunlight-illumination systems, solar trackers are always essential to obtain high energy/flux concentration efficiency, and that would lead to increase cost and extra power consumption due to the complex structure and heavy weight of the trackers. To decrease the cost while without sacrificing efficiency, a Fresnellens concentrator incorporated with a simple and cheap shutter, which consists of high reflective mirrors instead of conventional trackers, is proposed in this paper to provide solar tracking during the daytime. Thus, the time-variant and slant-incident sunlight rays can be redirected to vertically incident upon the surface of the Fresnel lens by appropriately arranging mirrors and swinging them to the proper slant angles with respect to the orientation of sunlight. The computer simulation results show that power concentration efficiency over 90%, as compared with the efficiency of directly normal incident sunlight, can be achieved with the mirror reflectance of 0.97 and for any solar incident angle within +/-75 degrees to the normal of the Fresnel lens. To verify the feasibility and performance of the concentrator with the proposed shutter, a sunlight illumination system based on this novel structure is demonstrated. Both computer simulation and practical measurement results for the prototype of the sunlight illumination system are also given to compare with. The results prove the simple and high efficient shutter applicable to general PV or sunlight-illumination systems for solar tracking.

  4. 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.

  5. FORMALDEHYDE AND METHANOL DEUTERATION IN PROTOSTARS: FOSSILS FROM A PAST FAST HIGH-DENSITY PRE-COLLAPSE PHASE

    SciTech Connect

    Taquet, V.; Ceccarelli, C.; Kahane, C.

    2012-03-20

    Extremely high deuteration of several molecules has been observed around low-mass protostars for a decade. Among them, formaldehyde and methanol present particularly high deuteration, with observations of abundant doubly and triply deuterated forms. Both species are thought to be mainly formed on interstellar grains during the low-temperature and dense pre-collapse phase by H and D atom additions on the iced CO. We present here a theoretical study of the formaldehyde and methanol deuteration obtained with our gas-grain model, GRAINOBLE. This model takes into account the multilayer nature of the mantle and explores the robustness of the results against the uncertainties of poorly constrained chemical and surface model parameters. The comparison of the model predictions with the observations leads to two major results: (1) the observed high deuteration is obtained during the last phase of the pre-collapse stage, when the density reaches {approx}5 Multiplication-Sign 10{sup 6} cm{sup -3}, and this phase is fast, lasting only several thousands years; and (2) D and H abstraction and substitution reactions are crucial in making up the observed deuteration ratios. This work shows the power of chemical composition as a tool to reconstruct the past history of protostars.

  6. Bandgap Engineering in High-Efficiency Multijunction Concentrator Cells

    SciTech Connect

    King, R. R.; Sherif, R. A.; Kinsey, G. S.; Kurtz, S.; Fetzer, C. M.; Edmondson, K. M.; Law, D. C.; Cotal, H. L.; Krut, D. D.; Ermer, J. H.; Karam, N. H.

    2005-08-01

    This paper discusses semiconductor device research paths under investigation with the aim of reaching the milestone efficiency of 40%. A cost analysis shows that achieving very high cell efficiencies is crucial for the realization of cost-effective photovoltaics, because of the strongly leveraging effect of efficiency on module packaging and balance-of systems costs. Lattice-matched (LM) GaInP/ GaInAs/ Ge 3-junction cells have achieved the highest independently confirmed efficiency at 175 suns, 25?C, of 37.3% under the standard AM1.5D, low-AOD terrestrial spectrum. Lattice-mismatched, or metamorphic (MM), materials offer still higher potential efficiencies, if the crystal quality can be maintained. Theoretical efficiencies well over 50% are possible for a MM GaInP/ 1.17-eV GaInAs/ Ge 3-junction cell limited by radiative recombination at 500 suns. The bandgap - open circuit voltage offset, (Eg/q) - Voc, is used as a valuable theoretical and experimental tool to characterize multijunction cells with subcell bandgaps ranging from 0.7 to 2.1 eV. Experimental results are presented for prototype 6-junction cells employing an active {approx}1.1-eV dilute nitride GaInNAs subcell, with active-area efficiency greater than 23% and over 5.3 V open-circuit voltage under the 1-sun AM0 space spectrum. Such cell designs have theoretical efficiencies under the terrestrial spectrum at 500 suns concentration exceeding 55% efficiency, even for lattice-matched designs.

  7. 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.

  8. Overview of SERI's high efficiency solar cell research

    NASA Technical Reports Server (NTRS)

    Benner, J. P.; Cole, L. A.; Leboeuf, C. M.

    1985-01-01

    The bulk of the research efforts supported by the Solar Energy Research Institute (SERI) High Efficiency Concepts area has been directed towards establishing the feasibility of achieving very high efficiencies, 30% for concentrator and more than 20% for thin film flat plate, in solar cell designs which could possibly be produced competitively. The research has accomplished a great deal during the past two years. Even though the desired performance levels have not yet been demonstrated, based on the recent progress, a greater portion of the terrestrial photovoltaics community believes that these efficiencies are attainable. The program will now allocate a larger portion of resources to low cost, large area deposition technology. The program is currently shifting greater emphasis on to the study of crystal growth in order to provide the understanding and tools needed to design a large area process.

  9. 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

  10. Potential high efficiency solar cells: Applications from space photovoltaic research

    NASA Technical Reports Server (NTRS)

    Flood, D. J.

    1986-01-01

    NASA involvement in photovoltaic energy conversion research development and applications spans over two decades of continuous progress. Solar cell research and development programs conducted by the Lewis Research Center's Photovoltaic Branch have produced a sound technology base not only for the space program, but for terrestrial applications as well. The fundamental goals which have guided the NASA photovoltaic program are to improve the efficiency and lifetime, and to reduce the mass and cost of photovoltaic energy conversion devices and arrays for use in space. The major efforts in the current Lewis program are on high efficiency, single crystal GaAs planar and concentrator cells, radiation hard InP cells, and superlattice solar cells. A brief historical perspective of accomplishments in high efficiency space solar cells will be given, and current work in all of the above categories will be described. The applicability of space cell research and technology to terrestrial photovoltaics will be discussed.

  11. Highly efficient solar cells based on poly(3-butylthiophene) nanowires.

    PubMed

    Xin, Hao; Kim, Felix Sunjoo; Jenekhe, Samson A

    2008-04-23

    Poly(3-butylthiophene) (P3BT) nanowires, prepared by solution-phase self-assembly, have been used to construct highly efficient P3BT/fullerene nanocomposite solar cells. The fullerene/P3BT nanocomposite films showed an electrically bicontinuous nanoscale morphology with average field-effect hole mobilities as high as 8.0 x 10(-3) cm2/Vs due to the interconnected P3BT nanowire network revealed by TEM and AFM imaging. The power conversion efficiency of fullerene/P3BT nanowire devices was 3.0% (at 100 mW/cm2, AM1.5) in air and found to be identical with our similarly tested fullerene/poly(3-hexylthiophene) photovoltaic cells. This discovery expands the scope of promising materials and architectures for efficient bulk heterojunction solar cells.

  12. Lamellar multilayer gratings with very high diffraction efficiency

    SciTech Connect

    Martynov, V.V. |; Yakshin, A.; Agafonov, Yu.A.; Padmore, H.A.

    1997-07-01

    The authors report here the development of a hard x-ray multilayer grating that has achieved an absolute efficiency of 34% at a wavelength of 1.54{angstrom}. The W-C multilayer itself has a reflectivity of 57% and the grating has a 0th order absolute efficiency of 36%. The origin of this extraordinarily high efficiency is that the short period and highly asymmetric structure of the gratings combined with its deep grooves allows light to interact with a large number of layer pairs. This increases angular separation of the diffraction orders and reduces the multilayer bandwidth to the point where there is little or no order to order overlap in the grating structure, and hence maximum intensity can be diffracted into a selected order. This paper reports on the development of an optimized multilayer grating and some of its unique characteristics.

  13. Conceptual Design of Low-Temperature Hydrogen Production and High-Efficiency Nuclear Reactor Technology

    NASA Astrophysics Data System (ADS)

    Fukushima, Kimichika; Ogawa, Takashi

    Hydrogen, a potential alternative energy source, is produced commercially by methane (or LPG) steam reforming, a process that requires high temperatures, which are produced by burning fossil fuels. However, as this process generates large amounts of CO2, replacement of the combustion heat source with a nuclear heat source for 773-1173K processes has been proposed in order to eliminate these CO2 emissions. In this paper, a novel method of nuclear hydrogen production by reforming dimethyl ether (DME) with steam at about 573K is proposed. From a thermodynamic equilibrium analysis of DME steam reforming, the authors identified conditions that provide high hydrogen production fraction at low pressure and temperatures of about 523-573K. By setting this low-temperature hydrogen production process upstream from a turbine and nuclear reactor at about 573K, the total energy utilization efficiency according to equilibrium mass and heat balance analysis is about 50%, and it is 75%for a fast breeder reactor (FBR), where turbine is upstream of the reformer.

  14. Aestivation in the fossil record: evidence from ichnology.

    PubMed

    Hembree, Daniel I

    2010-01-01

    Aestivation is a physiological and behavioral response to high temperature or low moisture conditions. Therefore, it is typically not considered to be capable of being preserved in the fossil record. However, most aestivating organisms produce a burrow to protect themselves from the harmful environmental conditions that trigger aestivation. These structures can be preserved in the rock record as trace fossils. While trace fossils are abundant in the continental fossil record, few are definitively associated with aestivation. Interpreting aestivation behavior from fossil burrows requires a detailed examination and interpretation of the surrounding sedimentary rocks and comparisons with taxonomically and ecologically similar extant organisms. Currently, only four types of aestivation structures are recognized in the fossil record: Pleistocene earthworm chambers, Devonian to Cretaceous lungfish burrows, Permian lysorophid burrows, and Permian to Triassic dicynodont burrows. The trace fossil evidence suggests that aestivation evolved independently among continental organisms in several clades during the middle to late Paleozoic.

  15. Progress in efficiency-optimized high-power diode lasers

    NASA Astrophysics Data System (ADS)

    Pietrzak, A.; Hülsewede, R.; Zorn, M.; Hirsekorn, O.; Sebastian, J.; Meusel, J.; Hennig, P.; Crump, P.; Wenzel, H.; Knigge, S.; Maaßdorf, A.; Bugge, F.; Erbert, G.

    2013-10-01

    High-power diode lasers are highly efficient sources of optical energy for industrial and defense applications, either directly or as pump sources for solid state or fiber lasers. We review here how advances in diode laser design and device technology have enabled the performance to be continuously improved. An overview is presented of recent progress at JENOPTIK in the development of commercial diode lasers optimized for peak performance, robust high-yield manufacture and long lifetimes. These diode lasers are tailored to simultaneously operate with reduced vertical carrier leakage, low thermal and electrical resistance and low optical losses. In this way, the highest electro-optical efficiencies are sustained to high currents. For example, 940-nm bars with high fill factor are shown to deliver continuous wave (CW) output powers of 280 W with conversion efficiency of < 60%. These bars have a vertical far field angle with 95% power content of just 40°. In addition, 955-nm single emitters with 90μm stripe width deliver 12 W CW output with power conversion efficiency at the operating point of 69%. In parallel, the Ferdinand-Braun-Institut (FBH) is working to enable the next generation of high power diode lasers, by determining the key limitations to performance and by pioneering new technologies to address these limits. An overview of recent studies at the FBH will therefore also be presented. Examples will include structures with further reduced far field angles, higher lateral beam quality and increased peak power and efficiency. Prospects for further performance improvement will be discussed.

  16. Advanced fossil energy utilization

    SciTech Connect

    Shekhawat, D.; Berry, D.; Spivey, J.; Pennline, H.; Granite, E.

    2010-01-01

    This special issue of Fuel is a selection of papers presented at the symposium ‘Advanced Fossil Energy Utilization’ co-sponsored by the Fuels and Petrochemicals Division and Research and New Technology Committee in the 2009 American Institute of Chemical Engineers (AIChE) Spring National Meeting Tampa, FL, on April 26–30, 2009.

  17. Trace Fossil Analysis

    NASA Astrophysics Data System (ADS)

    Hasiotis, Stephen T.

    2009-05-01

    Today, the study of trace fossils—ichnology—is an important subdiscipline of geology at the interface of paleontology and sedimentology, mostly because of the efforts of Adolf Seilacher. His ability to synthesize various aspects of ichnology and produce a hierarchy of marine ichna and sedimentary facies has made ichnology useful worldwide in interpreting paleodiversity, rates of sedimentation, oxygenation of bottom water and sediment pore water, and depositional energy. Seilacher's book Trace Fossil Analysis provides a glimpse into the mind, methodology, and insights of the father of modern ichnology, generated from his course notes as a professor and a guest lecturer. The title sounds misleading—readers looking for up-to-date principles and approaches to trace fossil analysis in marine and continental strata will be disappointed. In his preface, however, Seilacher clearly gives direction for the use of his text: “This is a course book—meaning that it is intended to confer not knowledge, but skill.” Thus, it is not meant as a total compilation of all trace fossils, ichnotaxonomy, ichnological interpretations, applications, or the most relevant and up-to-date references. Rather, it takes the reader on a personal journey, explaining how trace fossils are understood in the context of their three-dimensional (3-D) morphology and sedimentary facies.

  18. High efficiency solar cells for laser power beaming applications

    NASA Technical Reports Server (NTRS)

    Jain, Raj K.; Landis, G. A.

    1995-01-01

    Understanding solar cell response to pulsed laser outputs is important for the evaluation of power beaming applications. The time response of high efficiency GaAs and silicon solar cells to a 25 nS monochromatic pulse input is described. The PC-1D computer code is used to analyze the cell current during and after the pulse for various conditions.

  19. Applications of ion implantation for high efficiency silicon solar cells

    NASA Technical Reports Server (NTRS)

    Minnucci, J. A.; Kirkpatrick, A. R.

    1977-01-01

    Ion implantation is utilized for the dopant introduction processes necessary to fabricate a silicon solar cell. Implantation provides a versatile powerful tool for development of high efficiency cells. Advantages and problems of implantation and the present status of developmental use of the technique for solar cells are discussed.

  20. Development of High Efficiency (14%) Solar Cell Array Module

    NASA Technical Reports Server (NTRS)

    Iles, P. A.; Khemthong, S.; Olah, S.; Sampson, W. J.; Ling, K. S.

    1979-01-01

    High efficiency solar cells required for the low cost modules was developed. The production tooling for the manufacture of the cells and modules was designed. The tooling consisted of: (1) back contact soldering machine; (2) vacuum pickup; (3) antireflective coating tooling; and (4) test fixture.

  1. Super Boiler: First Generation, Ultra-High Efficiency Firetube Boiler

    SciTech Connect

    2006-06-01

    This factsheet describes a research project whose goal is to develop and demonstrate a first-generation ultra-high-efficiency, ultra-low emissions, compact gas-fired package boiler (Super Boiler), and formulate a long-range RD&D plan for advanced boiler technology out to the year 2020.

  2. LTC1877 High Efficiency Regulator Total Ionizing Dose Test Report

    NASA Technical Reports Server (NTRS)

    Oldham, Timothy; Pellish, Jonathan; Boutte, Alvin

    2012-01-01

    This report presents total ionizing dose evaluation data for the Linear Technology Corporation LTC1877 high efficiency monolithic synchronous step-down regulator. Data sheet parameters were tracked as a function of ionizing dose up to a total of 20 krad(SiO2). Control devices were also used.

  3. High-quantum efficiency, long-lived luminescing refractory oxides

    DOEpatents

    Chen, Y.; Gonzalez, R.; Summers, G.P.

    A crystal having a high-quantum efficiency and a long period of luminescence is formed of MgO or CaO and possessing a concentration ratio of H/sup -/ ions to F centers in the range of about 0.05 to about 10.

  4. High-quantum efficiency, long-lived luminescing refractory oxides

    DOEpatents

    Chen, Yok; Gonzalez, Roberto; Summers, Geoffrey P.

    1984-01-01

    A crystal having a high-quantum efficiency and a long period of luminescence is formed of an oxide selected from the group consisting of magnesium oxide and calcium oxide and possessing a concentration ratio of H.sup.- ions to F centers in the range of about 0.05 to about 10.

  5. 40 CFR 761.71 - High efficiency boilers.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... PROHIBITIONS Storage and Disposal § 761.71 High efficiency boilers. (a) To burn mineral oil dielectric fluid... percent (on a volume basis) of the total fuel feed rate. (v) The mineral oil dielectric fluid is not fed... feeding these fluids during either start up or shut down operations). (vi) The owner or operator of...

  6. Technical and economic feasibility study of solar/fossil hybrid power systems

    NASA Technical Reports Server (NTRS)

    Bloomfield, H. S.; Calogeras, J. E.

    1977-01-01

    Results show that new hybrid systems utilizing fossil fuel augmentation of solar energy can provide significant capital and energy cost benefits when compared with solar thermal systems requiring thermal storage. These benefits accrue from a reduction of solar collection area that results from both the use of highly efficient gas and combined cycle energy conversion subsystems and elimination of the requirement for long-term energy storage subsystems. Technical feasibility and fuel savings benefits of solar hybrid retrofit to existing fossil-fired, gas and vapor cycle powerplants was confirmed; however, economic viability of steam cycle retrofit was found to be dependent on the thermodynamic and operational characteristics of the existing powerplant.

  7. Selective flotation of fossil resin from Western coal. Final report, July 1, 1990--May 25, 1992

    SciTech Connect

    Jensen, G.F.; Miller, J.D.

    1992-05-25

    The proof-of-concept test program was designed to clarify a number of concerns that have been raised by coal companies who own the valuable resin resource. First, from laboratory bench-scale flotation experiments, a froth product from cleaner flotation containing more than 80% hexane-extractable resin at higher than 80% recovery can be produced. Pilot-plant testing was initiated to demonstrate the selective flotation of fossil resin and to establish a better confidence level in the new technology. Second, pilot-plant testing was designed to evaluate the effect and impact of random variation in slurry solids concentration and feed grade on this new selective fossil resin flotation technology. The flotation performance obtained under these industrial conditions is more realistic for process evaluation. Third, more accurate operating cost data was to be obtained for economic analysis. Fourth, sufficient quantities of the fossil resin concentrate were to be produced from the test program for evaluation by potential industrial users. Fifth, and finally, optimum levels for the operating variables were to be established. Such information was required for eventual scale-up and design of a fossil resin flotation plant. The pilot-plant proof-of-concept testing of selective resinate flotation has demonstrated that: (1) technically, the new flotation technologies discovered at the University of Utah and then improved upon by Advanced Processing Technologies, Inc. provide a highly efficient means to selectively recover fossil resin from coal. The proof-of-concept continuous flotation circuit (about 0.1 tph) resulted in fossil resin recovery with the same separation efficiency as was obtained from laboratory bench-scale testing (more than 80% recovery at about 80% concentrate grade); and (2) economically, the selective flotation process has been shown to be sufficiently profitable to justify the development of a fossil resin industry based on this new flotation process.

  8. High resolution mesurements of 18O/16O ratios of present and fossil herbivores dental enamel using the ims 1270 ion microprobe

    NASA Astrophysics Data System (ADS)

    Pisapia, C.; Bentaleb, I.; Rollion-Bard, C.; Tafforeau, P.; Fontugne, M.; France-Lanord, C.

    2003-04-01

    The isotopic composition of dental enamel is used for palaeoenvironmental issues. Enamel has a striated structure. Growth striations represent daily formation of enamel and precipitate as apatite cristals in equilibrium with the body water of the animal which mainly reflects the water ingested. The isotopic composition of meteoric water is well-correlated with environmental temperature. Enamel is the most mineralised biomaterial in comparison with dentine or bone and the isotopic signal is more easily preserved during fossilization. The knowledge of δ18O of enamel authorizes reconstruction of palaeotemperatures. The aim of this project is to develop the methodology for the analysis of the isotopic composition in oxygen (δ18O) of great herbivores enamel using the ims 1270 ion microprobe. This probe enables analyses at great resolution (spots diameter : 1-10μm) more than those obtained classically (eg. 50μm maximum with micromill sampling) for such studies. As a consequence, each analysis represents a smaller period of time and authorizes a precise description of past climates. Data obtained represent the bulk isotopic oxygen composition of bioapatite (PO_43-, CO_32- and OH groups). Instrumental deviation is corrected using mesurements of sedimentary hydroxyapatite and carbonate standards of known isotopic composition and calculating the relative proportion of these groups in the enamel analyzed: δinst = %carbonates^*δinst for carbonates + %hydroxyapatite ^*δinst for hydroxyapatite. Analyses were made on molars of present (Camelus dromedarius - Capra hircus: Pakistan, Ovis aries - Bos taurus: France) and fossil (Mammuthus primigenius: Siberia, Gaindatherium: Thailand) herbivores. First results on present or sub-present teeth showed coherent data (δ18O from 3.80 ppm for the Siberian mammoth to 27.77 ppm for the pakistanian goat) and seasonal variations of the signals are visible. Comparisons between bulk composition measured with ion microprobe and carbonates

  9. Fossil energy biotechnology: A research needs assessment. Final report

    SciTech Connect

    Not Available

    1993-11-01

    The Office of Program Analysis of the US Department of Energy commissioned this study to evaluate and prioritize research needs in fossil energy biotechnology. The objectives were to identify research initiatives in biotechnology that offer timely and strategic options for the more efficient and effective uses of the Nation`s fossil resource base, particularly the early identification of new and novel applications of biotechnology for the use or conversion of domestic fossil fuels. Fossil energy biotechnology consists of a number of diverse and distinct technologies, all related by the common denominator -- biocatalysis. The expert panel organized 14 technical subjects into three interrelated biotechnology programs: (1) upgrading the fuel value of fossil fuels; (2) bioconversion of fossil feedstocks and refined products to added value chemicals; and, (3) the development of environmental management strategies to minimize and mitigate the release of toxic and hazardous petrochemical wastes.

  10. High-efficiency heteroepitaxial solar cells for space power applications

    NASA Technical Reports Server (NTRS)

    Vernon, S. M.; Tobin, S. P.; Keavney, C. J.; Wojtczuk, S. J.

    1989-01-01

    The experimental results for several technical approaches aimed at achieving highly efficient solar cells for space-power applications are reported. Efficiencies of up to 24.5 percent (170X, AM0) and 21.7 percent (1X, AM0) have been achieved with homoepitaxial GaAs p/n cells. This one-sun AM0 efficiency value is believed to be the highest reported to date. Tandem solar cells utilizing GaAs-on-Ge structures have been fabricated and shown to have efficiencies up to 21.3 percent (1X, AM0), and a GaAs-on-Si cell at 15.2 percent (1X, AM0) is reported. Homoepitaxial n/p InP cells with an efficiency of 18.8 percent (1X, AM0) are also reported. The fabrication of heteroepitaxial InP solar cells with one-sun AM0 efficiency values of 9.4 percent (on GaAs) and 7.2 percent (on Si) is described.

  11. A Cooperative Interface for Highly Efficient Lithium-Sulfur Batteries.

    PubMed

    Peng, Hong-Jie; Zhang, Ze-Wen; Huang, Jia-Qi; Zhang, Ge; Xie, Jin; Xu, Wen-Tao; Shi, Jia-Le; Chen, Xiang; Cheng, Xin-Bing; Zhang, Qiang

    2016-11-01

    A cooperative interface constructed by "lithiophilic" nitrogen-doped graphene frameworks and "sulfiphilic" nickel-iron layered double hydroxides (LDH@NG) is proposed to synergistically afford bifunctional Li and S binding to polysulfides, suppression of polysulfide shuttles, and electrocatalytic activity toward formation of lithium sulfides for high-performance lithium-sulfur batteries. LDH@NG enables high rate capability, long lifespan, and efficient stabilization of both sulfur and lithium electrodes.

  12. A high efficiency 3 kW switchmode battery charger

    NASA Technical Reports Server (NTRS)

    Latos, T. S.; Bosack, D. J.

    1982-01-01

    This paper discusses the design approach and status of a high-efficiency switchmode battery charger designed to charge a 108 V battery from the 115 Vac line. The charger contains a transformer isolated boost chopper operating at 20 kHz. The boost inductor current is programmed to follow the ac line voltage such that high power factor operation and low line distortion are obtained.

  13. Multi-wavelength high efficiency laser system for lidar applications

    NASA Astrophysics Data System (ADS)

    Willis, Christina C. C.; Culpepper, Charles; Burnham, Ralph

    2015-09-01

    Motivated by the growing need for more efficient, high output power laser transmitters, we demonstrate a multi-wavelength laser system for lidar-based applications. The demonstration is performed in two stages, proving energy scaling and nonlinear conversion independently for later combination. Energy scaling is demonstrated using a 1064 nm MOPA system which employs two novel ceramic Nd:YAG slab amplifiers, the structure of which is designed to improve the amplifier's thermal performance and energy extraction via three progressive doping stages. This structure improved the extraction efficiency by 19% over previous single-stage dopant designs. A maximum energy of 34 mJ was produced at 500 Hz with a 10.8 ns pulse duration. High efficiency non-linear conversion from 1064 nm to 452 nm is demonstrated using a KTP ring OPO with a BBO intra-cavity doubler pumped with 50 Hz, 16 ns 1064 nm pulses. The OPO generates 1571 nm signal which is frequency doubled to 756 nm by the BBO. Output 786 nm pulses are mixed with the 1064 nm pump pulses to generate 452 nm. A conversion efficiency of 17.1% was achieved, generating 3 mJ of 452 nm pulses of 7.8 ns duration. Pump power was limited by intra-cavity damage thresholds, and in future experiments we anticipate >20% conversion efficiency.

  14. 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%.

  15. Encapsulation, with high efficiency, of radioactive metal ions in liposomes.

    PubMed

    Hwang, K J; Merriam, J E; Beaumier, P L; Luk, K F

    1982-05-05

    The encapsulation of radioactive metalic cations, such as 111In3+ or 67Ga3+, in the internal aqueous compartment of liposomes can be achieved with an efficiency of about 90%. The efficient loading of a high specific activity of cations into liposomes involves the transport of 111In3+ or 67Ga3+ through the lipid bilayer to an encapsulated strong chelate, such as nitrilotriacetic acid, by 8-hydroxyquinoline, in conjunction with an efficient anion-exchange resin technique for the removal of the external cations. The efficiency of loading cations to liposomes is affected markedly by the concentration of 8-hydroxyquinoline-metal, and the presence of the chelating agents in the loading incubation mixture. However, the loading efficiency is not affected by the pH of the internal aqueous compartment of liposomes over a range of pH 5-9, the concentration of the liposomes, the method of liposomal preparation, the lamellar structure of the liposomes, and the composition of liposomes. Furthermore, the loading procedures do not appear to affect the size and the permeability of liposomes. There is a good agreement in the tissue distributions of the liposomes prepared by the present loading methods and those by the conventional method of encapsulation by sonication. Liposomes entrapping high specific activity of 67Ga3+ or 111In3+ will be useful for future studies of the in vivo kinetics of liposomes by the combined techniques of scintigraphic imaging and the gamma-ray perturbed angular correlation.

  16. Ultra-Compact High-Efficiency Luminaire for General Illumination

    SciTech Connect

    Lowes, Ted

    2012-04-08

    Cree has developed a new ultra-compact light emitting diode (LED) luminaire capable of providing high efficacy with excellent color quality that can lead to significant energy savings in today's commercial and retail applications. This success was based on an integrated development effort tailoring the LED component characteristics, optics, thermal management and driver design for the small footprint to achieve an overall system efficiency of 70%. A new LED component was designed to provide high brightness and efficacy in a form factor that allowed for a small directional beam with a luminaire housing design able to dissipate the heat effectively using a small physical envelope. A very compact, 90% efficient driver was developed to meet the system performance while not taking away any thermal mass from the heat sink. A 91% efficient secondary optics was designed to maximize efficiency while providing a smooth beam. The reliability of the new LED component was robust under accelerated testing conditions. Luminaires were assembled integrating the novel LED component, secondary optics, heat sink and driver technology to demonstrate the system improvement. Cree has successfully completed this project by developing an ultra-compact LED luminaire that provided 380 lumens at a correlated color temperature (CCT) of 2822 K and color rendering index (CRI) of 94 with an efficacy of 94 lumens per watt (LPW) when operating at 4 W input power (steady state) with an overall system efficiency of 81%. At a higher input power of 9 Watts, the lamp provided 658 lumens at 71 LPW.

  17. Traversing the mountaintop: world fossil fuel production to 2050

    PubMed Central

    Nehring, Richard

    2009-01-01

    During the past century, fossil fuels—petroleum liquids, natural gas and coal—were the dominant source of world energy production. From 1950 to 2005, fossil fuels provided 85–93% of all energy production. All fossil fuels grew substantially during this period, their combined growth exceeding the increase in world population. This growth, however, was irregular, providing for rapidly growing per capita production from 1950 to 1980, stable per capita production from 1980 to 2000 and rising per capita production again after 2000. During the past half century, growth in fossil fuel production was essentially limited by energy demand. During the next half century, fossil fuel production will be limited primarily by the amount and characteristics of remaining fossil fuel resources. Three possible scenarios—low, medium and high—are developed for the production of each of the fossil fuels to 2050. These scenarios differ primarily by the amount of ultimate resources estimated for each fossil fuel. Total fossil fuel production will continue to grow, but only slowly for the next 15–30 years. The subsequent peak plateau will last for 10–15 years. These production peaks are robust; none of the fossil fuels, even with highly optimistic resource estimates, is projected to keep growing beyond 2050. World fossil fuel production per capita will thus begin an irreversible decline between 2020 and 2030. PMID:19770156

  18. A high-elevation, multi-proxy biotic and environmental record of MIS 6-4 from the Ziegler Reservoir fossil site, Snowmass Village, Colorado, USA

    USGS Publications Warehouse

    Miller, Ian M.; Pigati, Jeffrey S.; Anderson, R. Scott; Johnson, Kirk R.; Mahan, Shannon; Ager, Thomas A.; Baker, Richard G.; Blaauw, Maarten; Bright, Jordon; Brown, Peter M.; Bryant, Bruce; Calamari, Zachary T.; Carrara, Paul E.; Michael D., Cherney; Demboski, John R.; Elias, Scott A.; Fisher, Daniel C.; Gray, Harrison J.; Haskett, Danielle R.; Honke, Jeffrey S.; Jackson, Stephen T.; Jiménez-Moreno, Gonzalo; Kline, Douglas; Leonard, Eric M.; Lifton, Nathaniel A.; Lucking, Carol; McDonald, H. Gregory; Miller, Dane M.; Muhs, Daniel R.; Nash, Stephen E.; Newton, Cody; Paces, James B.; Petrie, Lesley; Plummer, Mitchell A.; Porinchu, David F.; Rountrey, Adam N.; Scott, Eric; Sertich, Joseph J. W.; Sharpe, Saxon E.; Skipp, Gary L.; Strickland, Laura E.; Stucky, Richard K.; Thompson, Robert S.; Wilson, Jim

    2014-01-01

    In North America, terrestrial records of biodiversity and climate change that span Marine Oxygen Isotope Stage (MIS) 5 are rare. Where found, they provide insight into how the coupling of the ocean–atmosphere system is manifested in biotic and environmental records and how the biosphere responds to climate change. In 2010–2011, construction at Ziegler Reservoir near Snowmass Village, Colorado (USA) revealed a nearly continuous, lacustrine/wetland sedimentary sequence that preserved evidence of past plant communities between ~ 140 and 55 ka, including all of MIS 5. At an elevation of 2705 m, the Ziegler Reservoir fossil site also contained thousands of well-preserved bones of late Pleistocene megafauna, including mastodons, mammoths, ground sloths, horses, camels, deer, bison, black bear, coyotes, and bighorn sheep. In addition, the site contained more than 26,000 bones from at least 30 species of small animals including salamanders, otters, muskrats, minks, rabbits, beavers, frogs, lizards, snakes, fish, and birds. The combination of macro- and micro-vertebrates, invertebrates, terrestrial and aquatic plant macrofossils, a detailed pollen record, and a robust, directly dated stratigraphic framework shows that high-elevation ecosystems in the Rocky Mountains of Colorado are climatically sensitive and varied dramatically throughout MIS 5.

  19. A high-elevation, multi-proxy biotic and environmental record of MIS 6–4 from the Ziegler Reservoir fossil site, Snowmass Village, Colorado, USA

    SciTech Connect

    Ian M. Miller; Mitchell A. Plummer; Various Others

    2014-10-01

    In North America, terrestrial records of biodiversity and climate change that span Marine Oxygen Isotope Stage (MIS) 5 are rare. Where found, they provide insight into how the coupling of the ocean–atmosphere system is manifested in biotic and environmental records and how the biosphere responds to climate change. In 2010–2011, construction at Ziegler Reservoir near Snowmass Village, Colorado (USA) revealed a nearly continuous, lacustrine/wetland sedimentary sequence that preserved evidence of past plant communities between ~140 and 55 ka, including all of MIS 5. At an elevation of 2705 m, the Ziegler Reservoir fossil site also contained thousands of well-preserved bones of late Pleistocene megafauna, including mastodons, mammoths, ground sloths, horses, camels, deer, bison, black bear, coyotes, and bighorn sheep. In addition, the site contained more than 26,000 bones from at least 30 species of small animals including salamanders, otters, muskrats, minks, rabbits, beavers, frogs, lizards, snakes, fish, and birds. The combination of macro- and micro-vertebrates, invertebrates, terrestrial and aquatic plant macrofossils, a detailed pollen record, and a robust, directly dated stratigraphic framework shows that high-elevation ecosystems in the Rocky Mountains of Colorado are climatically sensitive and varied dramatically throughout MIS 5

  20. Eocene high-latitude temperature gradients over time and space based on d18O values of fossil shark teeth

    NASA Astrophysics Data System (ADS)

    Zeichner, S. S.; Kim, S.; Colman, A. S.

    2015-12-01

    Early-Mid Eocene (56.0-33.9Mya) is characterized by a temperate Antarctic climate and shallower latitudinal temperature gradients than those in present day. The warmer waters off the coast of the Antarctic Peninsula provided suitable habitats for taxa (i.e., sharks) that live today at lower latitudes. Stable isotope analysis of Eocene shark teeth provides a proxy to understand high latitude temperature gradients. However, shark ecology, in particular migration and occupation of tidal versus pelagic habitats, must be considered in the interpretation of stable isotope data. In this study, we analyze d18OPO4 values from the enameloid of Striatolamia (synonymized with Carcharias) shark teeth from the La Meseta formation (Seymour Island, Antarctica) to estimate paleotemperature in Early-Mid Eocene Antarctica, and assess the impact of ecology versus environmental signals on d18OPO4 values. We compare the ranges and offsets between our measured shark tooth d18OPO4 and published bivalve d18OCO3 values to test whether shark teeth record signals of migration across latitudinal temperature gradients, or instead reflect seasonal and long-term temporal variation across La Meseta stratigraphic units.

  1. High efficiency low cost monolithic module for SARSAT distress beacons

    NASA Technical Reports Server (NTRS)

    Petersen, Wendell C.; Siu, Daniel P.

    1992-01-01

    The program objectives were to develop a highly efficient, low cost RF module for SARSAT beacons; achieve significantly lower battery current drain, amount of heat generated, and size of battery required; utilize MMIC technology to improve efficiency, reliability, packaging, and cost; and provide a technology database for GaAs based UHF RF circuit architectures. Presented in viewgraph form are functional block diagrams of the SARSAT distress beacon and beacon RF module as well as performance goals, schematic diagrams, predicted performances, and measured performances for the phase modulator and power amplifier.

  2. High-efficiency, 200 watt, 12-gigahertz traveling wave tube

    NASA Technical Reports Server (NTRS)

    Kosmahl, H. G.; Mcnary, B. D.; Sauseng, O.

    1974-01-01

    Design and performance of a highly efficient experimental 200-watt traveling wave tube for space communications are described. The tube uses a coupled cavity slow wave structure with periodic permanent magnet focusing. A two-step velocity taper is incorporated in the slow wave structure for velocity resynchronization with the modulated beam. The spent beam is reconditioned in a refocusing section before it is collected in a novel multistage depressed collector. The collector is radiation cooled and heat insulated from the tube body. At saturation the tube provides peak output power of 240 watts with a 35-db gain and an overall maximum efficiency of 56 percent.

  3. High efficiency fuel cell/advanced turbine power cycles

    SciTech Connect

    Morehead, H.

    1995-10-19

    An outline of the Westinghouse high-efficiency fuel cell/advanced turbine power cycle is presented. The following topics are discussed: The Westinghouse SOFC pilot manufacturing facility, cell scale-up plan, pressure effects on SOFC power and efficiency, sureCell versus conventional gas turbine plants, sureCell product line for distributed power applications, 20 MW pressurized-SOFC/gas turbine power plant, 10 MW SOFC/CT power plant, sureCell plant concept design requirements, and Westinghouse SOFC market entry.

  4. High-efficiency heteroepitaxial InP solar cells

    NASA Technical Reports Server (NTRS)

    Wanlass, M. W.; Coutts, T. J.; Ward, J. S.; Emery, K. A.

    1991-01-01

    High-efficiency, thin-film InP solar cells grown heteroepitaxially on GaAs and Si single-crystal bulk substrates are being developed as a means of eliminating the problems associated with using single-crystal InP substrates. A novel device structure employing a compositionally graded Ga(x)In(1-x)As layer between the bulk substrate and the InP cell layers is used to reduce the dislocation density and improve the minority carrier properties in the InP. The structures are grown in a continuous sequence of steps using computer-controlled atmospheric pressure metalorganic vapor phase epitaxy (APMOVPE). Dislocation densities as low as 3 x 10(exp 7) sq cm and minority carrier lifetimes as high as 3.3 ns are achieved in the InP layers with this method using both GaAs or Si substrates. Structures prepared in this fashion are also completely free of microcracks. These results represent a substantial improvement in InP layer quality when compared to heteroepitaxial InP prepared using conventional techniques such as thermally cycled growth and post-growth annealing. The present work is is concerned with the fabrication and characterization of high-efficiency, thin-film InP solar cells. Both one-sun and concentrator cells were prepared for device structures grown on GaAs substrates. One-cell cells have efficiencies as high as 13.7 percent at 25 C. However, results for the concentrator cells are emphasized. The concentrator cell performance is characterized as a function of the air mass zero (AM0) solar concentration ratio and operating temperature. From these data, the temperature coefficients of the cell performance parameters are derived as a function of the concentration ratio. Under concentration, the cells exhibit a dramatic increase in efficiency and an improved temperature coefficient of efficiency. At 25 C, a peak conversion efficiency of 18.9 percent is reported. At 80 C, the peak AM0 efficiency is 15.7 percent at 75.6 suns. These are the highest efficiencies yet

  5. Highly efficient beam steering with a transparent metasurface.

    PubMed

    Wei, Zeyong; Cao, Yang; Su, Xiaopeng; Gong, Zhijie; Long, Yang; Li, Hongqiang

    2013-05-06

    We propose an ultra-thin planar metasurface with phase discontinuities for highly efficient beam steering. The effect benefits from the broadband transparency and flexible phase modulation of stacked metal/dielectric multi-layers that is perforated with coaxial annular apertures. Proof-of-principle experiments verify that an efficiency of 65% and a deflection angle of 18° at 10 GHz are achieved for the transmitted beam, which are also in good agreement with the finite-difference-method-in-time-domain (FDTD) simulations. The scheme shall be general for the design of beam-steering transmitters in all frequencies.

  6. Highly Efficient Transition Metal Nanoparticle Catalysts in Aqueous Solutions.

    PubMed

    Wang, Changlong; Ciganda, Roberto; Salmon, Lionel; Gregurec, Danijela; Irigoyen, Joseba; Moya, Sergio; Ruiz, Jaime; Astruc, Didier

    2016-02-24

    A ligand design is proposed for transition metal nanoparticle (TMNP) catalysts in aqueous solution. Thus, a tris(triazolyl)-polyethylene glycol (tris-trz-PEG) amphiphilic ligand, 2, is used for the synthesis of very small TMNPs with Fe, Co, Ni, Cu, Ru, Pd, Ag, Pt, and Au. These TMNP-2 catalysts were evaluated and compared for the model 4-nitrophenol reduction, and proved to be extremely efficient. High catalytic efficiencies involving the use of only a few ppm metal of PdNPs, RuNPs, and CuNPs were also exemplified in Suzuki-Miyaura, transfer hydrogenation, and click reactions, respectively.

  7. Development of high efficiency (14 percent) solar cell array module

    NASA Technical Reports Server (NTRS)

    Iles, P. A.; Khemthong, S.; Olah, S.; Sampson, W. J.; Ling, K. S.

    1980-01-01

    Most effort was concentrated on development of procedures to provide large area (3 in. diameter) high efficiency (16.5 percent AM1, 28 C) P+NN+ solar cells. Intensive tests with 3 in. slices gave consistently lower efficiency (13.5 percent). The problems were identified as incomplete formation of and optimum back surface field (BSF), and interaction of the BSF process and the shallow P+ junction. The problem was shown not to be caused by reduced quality of silicon near the edges of the larger slices.

  8. Efficiency and Loading Evaluation of High Efficiency Mist Eliminators (HEME) - 12003

    SciTech Connect

    Giffin, Paxton K.; Parsons, Michael S.; Waggoner, Charles A.

    2012-07-01

    High efficiency mist eliminators (HEME) are filters primarily used to remove moisture and/or liquid aerosols from an air stream. HEME elements are designed to reduce aerosol and particulate load on primary High Efficiency Particulate Air (HEPA) filters and to have a liquid particle removal efficiency of approximately 99.5% for aerosols down to sub-micron size particulates. The investigation presented here evaluates the loading capacity of the element in the absence of a water spray cleaning system. The theory is that without the cleaning system, the HEME element will suffer rapid buildup of solid aerosols, greatly reducing the particle loading capacity. Evaluation consists of challenging the element with a waste surrogate dry aerosol and di-octyl phthalate (DOP) at varying intervals of differential pressure to examine the filtering efficiency of three different element designs at three different media velocities. Also, the elements are challenged with a liquid waste surrogate using Laskin nozzles and large dispersion nozzles. These tests allow the loading capacity of the unit to be determined and the effectiveness of washing down the interior of the elements to be evaluated. (authors)

  9. High Efficiency LED Lamp for Solid-State Lighting

    SciTech Connect

    James Ibbetson

    2006-12-31

    This report contains a summary of technical achievements during a three-year project to demonstrate high efficiency, solid-state lamps based on gallium nitride/silicon carbide light-emitting diodes. Novel chip designs and fabrication processes are described for a new type of nitride light-emitting diode with the potential for very high efficiency. This work resulted in the demonstration of blue light-emitting diodes in the one watt class that achieved up to 495 mW of light output at 350 mA drive current, corresponding to quantum and wall plug efficiencies of 51% and 45%, respectively. When combined with a phosphor in Cree's 7090 XLamp package, these advanced blue-emitting devices resulted in white light-emitting diodes whose efficacy exceeded 85 lumens per watt. In addition, up to 1040 lumens at greater than 85 lumens per watt was achieved by combining multiple devices to make a compact white lamp module with high optical efficiency.

  10. High Efficiency Microwave Power Amplifier: From the Lab to Industry

    NASA Technical Reports Server (NTRS)

    Sims, William Herbert, III; Bell, Joseph L. (Technical Monitor)

    2001-01-01

    Since the beginnings of space travel, various microwave power amplifier designs have been employed. These included Class-A, -B, and -C bias arrangements. However, shared limitation of these topologies is the inherent high total consumption of input power associated with the generation of radio frequency (RF)/microwave power. The power amplifier has always been the largest drain for the limited available power on the spacecraft. Typically, the conversion efficiency of a microwave power amplifier is 10 to 20%. For a typical microwave power amplifier of 20 watts, input DC power of at least 100 watts is required. Such a large demand for input power suggests that a better method of RF/microwave power generation is required. The price paid for using a linear amplifier where high linearity is unnecessary includes higher initial and operating costs, lower DC-to-RF conversion efficiency, high power consumption, higher power dissipation and the accompanying need for higher capacity heat removal means, and an amplifier that is more prone to parasitic oscillation. The first use of a higher efficiency mode of power generation was described by Baxandall in 1959. This higher efficiency mode, Class-D, is achieved through distinct switching techniques to reduce the power losses associated with switching, conduction, and gate drive losses of a given transistor.

  11. Broadband high-efficiency dielectric metasurfaces for the visible spectrum

    PubMed Central

    Devlin, Robert C.; Khorasaninejad, Mohammadreza; Chen, Wei Ting; Oh, Jaewon; Capasso, Federico

    2016-01-01

    Metasurfaces are planar optical elements that hold promise for overcoming the limitations of refractive and conventional diffractive optics. Original dielectric metasurfaces are limited to transparency windows at infrared wavelengths because of significant optical absorption and loss at visible wavelengths. Thus, it is critical that new materials and nanofabrication techniques be developed to extend dielectric metasurfaces across the visible spectrum and to enable applications such as high numerical aperture lenses, color holograms, and wearable optics. Here, we demonstrate high performance dielectric metasurfaces in the form of holograms for red, green, and blue wavelengths with record absolute efficiency (>78%). We use atomic layer deposition of amorphous titanium dioxide with surface roughness less than 1 nm and negligible optical loss. We use a process for fabricating dielectric metasurfaces that allows us to produce anisotropic, subwavelength-spaced dielectric nanostructures with shape birefringence. This process is capable of realizing any high-efficiency metasurface optical element, e.g., metalenses and axicons. PMID:27601634

  12. Highly efficient exciplex phosphorescence from organic light-emitting diodes

    NASA Astrophysics Data System (ADS)

    Virgili, D.; Cocchi, M.; Fattori, V.; Sabatini, C.; Kalinowski, J.; Williams, J. A. G.

    2006-12-01

    The efficiency of organic exciplex light-emitting-devices (EXLEDs) can be greatly improved by introduction of a phosphorescent sensitizer with a high electronic affinity. In the electron-hole combination process at the electron donor/acceptor interface, solely singlet exciplexes are generated producing the exciplex fluorescence. A phosphor sensitizer allows the formation in the emitter bulk of triplet exciplexes, which yield highly efficient exciplex phosphorescence. As an example, we use a Pt-based phosphor (PtL 2Cl) doped into a star-burst amine hole transporting donor (m-MTDATA) and bathophenanthroline (BPT) electron-transporting acceptor system which in a bi-layer EXLED reveals an exciplex high electro-phosphorescence external quantum yield of 2.4% photon/carrier.

  13. Groove shape characteristics of echelle gratings with high diffraction efficiency

    NASA Astrophysics Data System (ADS)

    Zhang, Shanwen; Mi, Xiaotao; Zhang, Qian; Jirigalantu; Feng, Shulong; Yu, Haili; Qi, Xiangdong

    2017-03-01

    The groove shape characteristics of echelle gratings with high diffraction efficiency are investigated. Using the coordinate transformation method (C method), an r-2 aluminum echelle with 79 grooves/mm is optimized through rigorous numerical simulations and shows high diffraction efficiency of 76-81% in the high Littrow orders. A grating is found to be essentially an echelle if it contains a series of reflective facets with a specific tilt angle that are located far from the nonworking facet of the grating and have a deep groove depth; any groove shape that meets these conditions can be called an echelle grating. The underlying mechanism is analyzed phenomenologically using electromagnetic theory. The universal model proposed here, which represents a new cognitive understanding of the concept of the echelle, is ready for use in manufacturing applications and offers a new perspective for the fabrication of these gratings.

  14. Broadband high-efficiency dielectric metasurfaces for the visible spectrum.

    PubMed

    Devlin, Robert C; Khorasaninejad, Mohammadreza; Chen, Wei Ting; Oh, Jaewon; Capasso, Federico

    2016-09-20

    Metasurfaces are planar optical elements that hold promise for overcoming the limitations of refractive and conventional diffractive optics. Original dielectric metasurfaces are limited to transparency windows at infrared wavelengths because of significant optical absorption and loss at visible wavelengths. Thus, it is critical that new materials and nanofabrication techniques be developed to extend dielectric metasurfaces across the visible spectrum and to enable applications such as high numerical aperture lenses, color holograms, and wearable optics. Here, we demonstrate high performance dielectric metasurfaces in the form of holograms for red, green, and blue wavelengths with record absolute efficiency (>78%). We use atomic layer deposition of amorphous titanium dioxide with surface roughness less than 1 nm and negligible optical loss. We use a process for fabricating dielectric metasurfaces that allows us to produce anisotropic, subwavelength-spaced dielectric nanostructures with shape birefringence. This process is capable of realizing any high-efficiency metasurface optical element, e.g., metalenses and axicons.

  15. High Quality Down Lighting Luminaire with 73% Overall System Efficiency

    SciTech Connect

    Robert Harrison; Steven C. Allen; Joseph Bernier; Robert Harrison

    2010-08-31

    This report summarizes work to develop a high flux, high efficiency LED-based downlight at OSRAM SYLVANIA under US Department of Energy contract DE-FC26-08NT01582. A new high power LED and electronic driver were developed for these downlights. The LED achieved 100 lumens per watt efficacy and 1700 lumen flux output at a correlated color temperature of 3500K. The driver had 90% electrical conversion efficiency while maintaining excellent power quality with power factor >0.99, and total harmonic distortion <10%. Two styles of downlights using the LED and driver were shown to exceed the project targets for steady-state luminous efficacy and flux of 70 lumens per watt and 1300 lumens, respectively. Compared to similar existing downlights using compact fluorescent or LED sources, these downlights had much higher efficacy at nearly the same luminous flux.

  16. 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.

  17. Optically Thin Metallic Films for High-Radiative-Efficiency Plasmonics.

    PubMed

    Yang, Yi; Zhen, Bo; Hsu, Chia Wei; Miller, Owen D; Joannopoulos, John D; Soljačić, Marin

    2016-07-13

    Plasmonics enables deep-subwavelength concentration of light and has become important for fundamental studies as well as real-life applications. Two major existing platforms of plasmonics are metallic nanoparticles and metallic films. Metallic nanoparticles allow efficient coupling to far field radiation, yet their synthesis typically leads to poor material quality. Metallic films offer substantially higher quality materials, but their coupling to radiation is typically jeopardized due to the large momentum mismatch with free space. Here, we propose and theoretically investigate optically thin metallic films as an ideal platform for high-radiative-efficiency plasmonics. For far-field scattering, adding a thin high-quality metallic substrate enables a higher quality factor while maintaining the localization and tunability that the nanoparticle provides. For near-field spontaneous emission, a thin metallic substrate, of high quality or not, greatly improves the field overlap between the emitter environment and propagating surface plasmons, enabling high-Purcell (total enhancement >10(4)), high-quantum-yield (>50%) spontaneous emission, even as the gap size vanishes (3-5 nm). The enhancement has almost spatially independent efficiency and does not suffer from quenching effects that commonly exist in previous structures.

  18. Ants and the fossil record.

    PubMed

    LaPolla, John S; Dlussky, Gennady M; Perrichot, Vincent

    2013-01-01

    The dominance of ants in the terrestrial biosphere has few equals among animals today, but this was not always the case. The oldest ants appear in the fossil record 100 million years ago, but given the scarcity of their fossils, it is presumed they were relatively minor components of Mesozoic insect life. The ant fossil record consists of two primary types of fossils, each with inherent biases: as imprints in rock and as inclusions in fossilized resins (amber). New imaging technology allows ancient ant fossils to be examined in ways never before possible. This is particularly helpful because it can be difficult to distinguish true ants from non-ants in Mesozoic fossils. Fossil discoveries continue to inform our understanding of ancient ant morphological diversity, as well as provide insights into their paleobiology.

  19. A high-efficiency, low-cost aeolian sand trap

    NASA Astrophysics Data System (ADS)

    Sherman, D. J.; Swann, C.; Barron, J. D.

    2014-06-01

    We present a design for an aeolian sand trap that is based on the streamer trap concept used in sediment transport studies. The trap is inexpensive, has excellent trapping efficiency, is durable, and easy to use. It is fabricated from stainless steel that is cut and bent to form a frame to support a fine nylon mesh. Typical trap openings are 100 mm wide and 25, 50, or 100 mm high. Traps are 250 mm long, and are stackable to measure vertical characteristics of saltation. The nylon mesh has 64 μm openings that comprise 47% of the area of the material. Aerodynamic efficiency was tested in a wind tunnel, and sediment trapping efficiency evaluated in field deployments. Both evaluations support the use of this trap for short-term measurements.

  20. High-Absorption-Efficiency Superlattice Solar Cells by Excitons

    NASA Astrophysics Data System (ADS)

    Nishinaga, Jiro; Kawaharazuka, Atsushi; Onomitsu, Koji; Horikoshi, Yoshiji

    2013-11-01

    The effect of excitonic absorption on solar cell efficiency has been investigated using solar cells with AlGaAs/GaAs superlattice structures. Numerical calculations reveal that excitonic absorption considerably enhances the overall absorption of bulk GaAs. Excitonic absorption shows strong and sharp peaks at the absorption edge and in the energy region above the band gap. Absorption enhancement is also achieved in the AlGaAs/GaAs superlattice. The measured quantum efficiency spectra of the superlattice solar cells are quite similar to the calculated absorption spectra considering the excitonic effect. The superlattice solar cells are confirmed to have high absorption coefficient compared with the GaAs and AlGaAs bulk solar cells. These results suggest that the enhanced absorption by excitons can increase the quantum efficiency of solar cells. This effect is more prominent for the solar cells with small absorption layer thicknesses.

  1. 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.

  2. High Efficiency InP Solar Cells Through Nanostructuring

    NASA Astrophysics Data System (ADS)

    Goldman, Daniel; Murray, Joseph; Munday, Jeremy

    We describe high efficiency InP solar cells which utilize a periodic array of optically designed TiO2 nanocylinders. Optical and electronic simulations were performed to determine the spectrally resolved reflectivity and I-V characteristics of potential devices under AM1.5G illumination. The reflectivity of InP solar cells with these nanocylinders is found to have an average value of 2% over the visible and near-IR spectral range, which outperforms traditional antireflection coatings. Coupling between Mie scattering resonances and thin film interference effects is found to accurately describe the optical enhancement provided by the nanocylinders. These nanostructured solar cells have power conversion efficiencies greater than 23%, which is comparable to the highest quoted efficiencies for InP solar cells.

  3. Predicting high harmonic ion cyclotron heating efficiency in Tokamak plasmas.

    PubMed

    Green, D L; Berry, L A; Chen, G; Ryan, P M; Canik, J M; Jaeger, E F

    2011-09-30

    Observations of improved radio frequency (rf) heating efficiency in ITER relevant high-confinement (H-)mode plasmas on the National Spherical Tokamak Experiment are investigated by whole-device linear simulation. The steady-state rf electric field is calculated for various antenna spectra and the results examined for characteristics that correlate with observations of improved or reduced rf heating efficiency. We find that launching toroidal wave numbers that give fast-wave propagation in the scrape-off plasma excites large amplitude (∼kV m(-1)) coaxial standing modes between the confined plasma density pedestal and conducting vessel wall. Qualitative comparison with measurements of the stored plasma energy suggests that these modes are a probable cause of degraded heating efficiency.

  4. High efficiency deep-blue and white phosphorescent OLEDs

    NASA Astrophysics Data System (ADS)

    Xue, Jiangeng; Eom, Sang-Hyun; Zheng, Ying; Wrzesniewski, Edward; Chopra, Neetu; Lee, Jaewon; So, Franky

    2009-08-01

    We report studies on blue and white organic light-emitting devices (OLEDs) based on the deep-blue electrophosphorescent dye iridium(III) bis(4',6'-difluorophenylpyridinato)tetrakis(1-pyrazolyl)borate (FIr6). Using high triplet energy charge transport layers and a dual-emissive-layer structure as well as the p-i-n device structure, we have achieved external quantum efficiencies of 20% and maximum power efficiency of 36 lm/W in these deep-blue OLEDs. White OLEDs with a CRI of 79 and a maximum power efficiency of 40 lm/W were also demonstrated by incorporating red and green phosphorescent dopants together with FIr6.

  5. Micronized coal-fired retrofit system for SO{sub x} reduction Krakow clean fossil fuels and energy efficiency program. Final report

    SciTech Connect

    1997-04-01

    This report describes results of a technical, financial and environmental assessment study for a project, which would have included a new TCS micronized coal-fired heating plant for the Produkcja I Hodowla Roslin Ogrodniczych (PHRO) Greenhouse Complex; Krzeszowice, Poland. Project site is about 20 miles west of Krakow, Poland. During the project study period, PHRO utilized 14 heavy oil-fired boilers to produce heat for its greenhouse facilities and also home heating to several adjacent apartment housing complexes. The boilers burn a high-sulfur content heavy crude oil, called mazute, The project study was conducted during a period extended from March 1996 through February 1997. For size orientation, the PHRO Greenhouse complex grows a variety of vegetables and flowers for the Southern Poland marketplace. The greenhouse area under glass is very large and equivalent to approximately 50 football fields, The new micronized coal fired boiler would have: (1) provided a significant portion of the heat for PHRO and a portion of the adjacent apartment housing complexes, (2) dramatically reduced sulfur dioxide air pollution emissions, while satisfying new Polish air regulations, and (3) provided attractive savings to PHRO, based on the quantity of displaced oil.

  6. High-Efficiency Harmonically Terminated Diode and Transistor Rectifiers

    SciTech Connect

    Roberg, M; Reveyrand, T; Ramos, I; Falkenstein, EA; Popovic, Z

    2012-12-01

    This paper presents a theoretical analysis of harmonically terminated high-efficiency power rectifiers and experimental validation on a class-C single Schottky-diode rectifier and a class-F-1 GaN transistor rectifier. The theory is based on a Fourier analysis of current and voltage waveforms, which arise across the rectifying element when different harmonic terminations are presented at its terminals. An analogy to harmonically terminated power amplifier (PA) theory is discussed. From the analysis, one can obtain an optimal value for the dc load given the RF circuit design. An upper limit on rectifier efficiency is derived for each case as a function of the device on-resistance. Measured results from fundamental frequency source-pull measurement of a Schottky diode rectifier with short-circuit terminations at the second and third harmonics are presented. A maximal device rectification efficiency of 72.8% at 2.45 GHz matches the theoretical prediction. A 2.14-GHz GaN HEMT rectifier is designed based on a class-F-1 PA. The gate of the transistor is terminated in an optimal impedance for self-synchronous rectification. Measurements of conversion efficiency and output dc voltage for varying gate RF impedance, dc load, and gate bias are shown with varying input RF power at the drain. The rectifier demonstrates an efficiency of 85% for a 10-W input RF power at the transistor drain with a dc voltage of 30 V across a 98-Omega resistor.

  7. Research on stable, high-efficiency amorphous silicon multijunction modules

    SciTech Connect

    Banerjee, A.; Chen, E.; Clough, R.; Glatfelter, T.; Guha, S.; Hammond, G.; Hopson, M.; Jackett, N.; Lycette, M.; Noch, J.; Palmer, T.; Pawlikiewicz, A.; Rosenstein, I.; Ross, R.; Wolf, D.; Xu, X.; Yang, J.; Younan, K.

    1992-04-01

    This report describes the progress made during Phase 1 of research and development program to obtain high-efficiency amorphous silicon alloy multijunction modules. Using a large-area deposition system, double-and triple-junction cells were made on stainless steel substrates of over 1 ft{sup 2} area with Ag and ZnO predeposited back reflector. Modules of over 1 ft{sup 2} were produced with between 9.2% and 9.9 initial aperture-area efficiencies as measured under a USSC Spire solar simulator. Efficiencies as measured under the NREL Spire solar simulator were found to be typically 15% to 18% lower. The causes for this discrepancy are now being investigated. The modules show about 15% degradation after 600 hours of one-sun illumination at 50{degrees}C. To optimize devices for higher stabilized efficiency, a new method was developed by which the performance of single-junction cells after long-term, one-sun exposure at 50{degrees}C can be predicted by exposing cells to short-term intense light at different temperatures. This method is being used to optimize the component cells of the multijunction structure to obtain the highest light-degraded efficiency.

  8. Advanced Klystrons for High Efficiency Accelerator Systems - Final Report

    SciTech Connect

    Read, Michael; Ives, Robert Lawrence

    2014-03-26

    This program explored tailoring of RF pulses used to drive accelerator cavities. Simulations indicated that properly shaping the pulse risetime to match accelerator cavity characteristics reduced reflected power and increased total efficiency. Tailoring the pulse requires a high power, gridded, klystron to shape the risetime while also controlling the beam current. The Phase I program generated a preliminary design of a gridded electron gun for a klystron producing 5-10 MW of RF power. This required design of a segmented cathode using Controlled Porosity Reservoir cathodes to limit power deposition on the grid. The program was successful in computationally designing a gun producing a high quality electron beam with grid control. Additional analysis of pulse tailoring indicated that technique would only be useful for cavity drive pulses that were less than approximately 2-3 times the risetime. Otherwise, the efficiency gained during the risetime of the pulse became insignificant when considering the efficiency over the entire pulse. Consequently, it was determined that a Phase II program would not provide sufficient return to justify the cost. Never the less, other applications for a high power gridded gun are currently being pursued. This klystron, for example, would facilitate development inverse Comptom x-ray sources by providing a high repetition rate (10 -100 kHz) RF source.

  9. High-efficiency nanostructured window GaAs solar cells.

    PubMed

    Liang, Dong; Kang, Yangsen; Huo, Yijie; Chen, Yusi; Cui, Yi; Harris, James S

    2013-10-09

    Nanostructures have been widely used in solar cells due to their extraordinary optical properties. In most nanostructured cells, high short circuit current has been obtained due to enhanced light absorption. However, most of them suffer from lowered open circuit voltage and fill factor. One of the main challenges is formation of good junction and electrical contact. In particular, nanostructures in GaAs only have shown unsatisfactory performances (below 5% in energy conversion efficiency) which cannot match their ideal material properties and the record photovoltaic performances in industry. Here we demonstrate a completely new design for nanostructured solar cells that combines nanostructured window layer, metal mesa bar contact with small area, high quality planar junction. In this way, we not only keep the advanced optical properties of nanostructures such as broadband and wide angle antireflection, but also minimize its negative impact on electrical properties. High light absorption, efficient carrier collection, leakage elimination, and good lateral conductance can be simultaneously obtained. A nanostructured window cell using GaAs junction and AlGaAs nanocone window demonstrates 17% energy conversion efficiency and 0.982 V high open circuit voltage.

  10. 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.

  11. Efficiency Analysis of a High-Specific Impulse Hall Thruster

    NASA Technical Reports Server (NTRS)

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

    2004-01-01

    Performance and plasma measurements of the high-specific impulse NASA-173Mv2 Hall thruster were analyzed using a phenomenological performance model that accounts for a partially-ionized plasma containing multiply-charged ions. Between discharge voltages of 300 to 900 V, the results showed that although the net decrease of efficiency due to multiply-charged ions was only 1.5 to 3.0 percent, the effects of multiply-charged ions on the ion and electron currents could not be neglected. Between 300 to 900 V, the increase of the discharge current was attributed to the increasing fraction of multiply-charged ions, while the maximum deviation of the electron current from its average value was only +5/-14 percent. These findings revealed how efficient operation at high-specific impulse was enabled through the regulation of the electron current with the applied magnetic field. Between 300 to 900 V, the voltage utilization ranged from 89 to 97 percent, the mass utilization from 86 to 90 percent, and the current utilization from 77 to 81 percent. Therefore, the anode efficiency was largely determined by the current utilization. The electron Hall parameter was nearly constant with voltage, decreasing from an average of 210 at 300 V to an average of 160 between 400 to 900 V. These results confirmed our claim that efficient operation can be achieved only over a limited range of Hall parameters.

  12. 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.

  13. 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).

  14. High efficiency GaAs/Ge monolithic tandem solar cells

    NASA Technical Reports Server (NTRS)

    Tobin, S. P.; Vernon, S. M.; Bajgar, C.; Haven, V. E.; Geoffroy, L. M.; Sanfacon, M. M.; Lillington, D. R.; Hart, R. E., Jr.

    1988-01-01

    Two-terminal monolithic tandem cells consisting of a GaAs solar cell grown epitaxially on a Ge solar cell substrate are very attractive for space applications. Tandem cells of GaAs grown by metal-organic chemical vapor deposition on thin Ge were investigated to address both higher efficiency and reduced weight. Two materials growth issues associated with this heteroepitaxial system, autodoping of the GaAs layers by Ge and diffusion of Ga and As into the Ge substrate, were addressed. The latter appears to result in information of an unintentional p-n junction in the Ge. Early simulator measurements gave efficiencies as high as 21.7 percent for 4 cm2 GaAs/Ge cells, but recent high-altitude testing has given efficiencies of 18 percent. Sources of errors in simulator measurements of two-terminal tandem cells are discussed. A limiting efficiency of about 36 percent for the tandem cell at AMO was calculated. Ways to improve the performance of present cells, primarily by increasing the Isc and Voc of the Ge cell, are proposed.

  15. Test Program for High Efficiency Gas Turbine Exhaust Diffuser

    SciTech Connect

    Norris, Thomas R.

    2009-12-31

    This research relates to improving the efficiency of flow in a turbine exhaust, and thus, that of the turbine and power plant. The Phase I SBIR project demonstrated the technical viability of “strutlets” to control stalls on a model diffuser strut. Strutlets are a novel flow-improving vane concept intended to improve the efficiency of flow in turbine exhausts. Strutlets can help reduce turbine back pressure, and incrementally improve turbine efficiency, increase power, and reduce greenhouse gas emmission. The long-term goal is a 0.5 percent improvement of each item, averaged over the US gas turbine fleet. The strutlets were tested in a physical scale model of a gas turbine exhaust diffuser. The test flow passage is a straight, annular diffuser with three sets of struts. At the end of Phase 1, the ability of strutlets to keep flow attached to struts was demonstrated, but the strutlet drag was too high for a net efficiency advantage. An independently sponsored followup project did develop a highly-modified low-drag strutlet. In combination with other flow improving vanes, complicance to the stated goals was demonstrated for for simple cycle power plants, and to most of the goals for combined cycle power plants using this particular exhaust geometry. Importantly, low frequency diffuser noise was reduced by 5 dB or more, compared to the baseline. Appolicability to other diffuser geometries is yet to be demonstrated.

  16. 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-

  17. Research on stable, high efficiency amorphous silicon multijunction modules

    SciTech Connect

    Catalano, A.; Arya, R.R.; Bennett, M.; Chen, L.; D'Aiello, R.; Fieselmann, B.; Li, Y.; Newton, J.; Podlesny, R.; Wiedeman, S.; Yang, L. . Thin Film Div.)

    1992-02-01

    Improvements towards a goal of a 12.5% initial triple-junction module efficiency require the use of a wide gap top-layer for improved open circuit voltage, higher transmission from the transparent front contact and more highly transmitting doped layers. To address the first issue, there has been continued development of a-SiC:H with the utilization of several novel feedstocks to control the atomic structure of the solid. These films have transport properties superior to the best results reported for a-SiC:H. Preliminary results with devices exhibits a stability comparable to a-Si:H, while previous results with a-SiC:H have generally shown for higher rates of degradation. Module fabrication has been refined to the extent that comparable module and small area device efficiencies are readily obtained. Despite the high initial efficiencies (9%--10%) obtained in 935 cm{sup 2} modules employing devices with 4000{Angstrom} thick middle junctions, higher than expected rates of degradation were found. The cause of the anomalous degradation was traced to shunts present in the device arising from defects in the tin oxide coating. NREL degradation results of triple-junction modules showed stabilized performance of the initial efficiency for modules prepared during the period in which shunts were a problem. 20 refs.

  18. Fe-Al Weld Overlay and High Velocity Oxy-Fuel Thermal Spray Coatings for Corrosion Protection of Waterwalls in Fossil Fired Plants with Low NOx Burners

    SciTech Connect

    Regina, J.R.

    2002-02-08

    Iron-aluminum-chromium coatings were investigated to determine the best candidates for coatings of boiler tubes in Low NOx fossil fueled power plants. Ten iron-aluminum-chromium weld claddings with aluminum concentrations up to 10wt% were tested in a variety of environments to evaluate their high temperature corrosion resistance. The weld overlay claddings also contained titanium additions to investigate any beneficial effects from these ternary and quaternary alloying additions. Several High-Velocity Oxy-Fuel (HVOF) thermal spray coatings with higher aluminum concentrations were investigated as well. Gaseous corrosion testing revealed that at least 10wt%Al is required for protection in the range of environments examined. Chromium additions were beneficial in all of the environments, but additions of titanium were beneficial only in sulfur rich atmospheres. Similar results were observed when weld claddings were in contact with corrosive slag while simultaneously, exposed to the corrosive environments. An aluminum concentration of 10wt% was required to prevent large amounts of corrosion to take place. Again chromium additions were beneficial with the greatest corrosion protection occurring for welds containing both 10wt%Al and 5wt%Cr. The exposed thermal spray coatings showed either significant cracking within the coating, considerable thickness loss, or corrosion products at the coating substrate interface. Therefore, the thermal spray coatings provided the substrate very little protection. Overall, it was concluded that of the coatings studied weld overlay coatings provide superior protection in these Low NOx environments; specifically, the ternary weld composition of 10wt%Al and 5wt%Cr provided the best corrosion protection in all of the environments tested.

  19. High-efficiency silicon heterojunction solar cells: Status and perspectives

    SciTech Connect

    De Wolf, S.

    2015-04-27

    Silicon heterojunction technology (HJT) uses silicon thin-film deposition techniques to fabricate photovoltaic devices from mono-crystalline silicon wafers (c-Si). This enables energy-conversion efficiencies above 21 %, also at industrial-production level. In this presentation we review the present status of this technology and point out recent trends. We first discuss how the properties of thin hydrogenated amorphous silicon (a-Si:H) films can be exploited to fabricate passivating contacts, which is the key to high- efficiency HJT solar cells. Such contacts enable very high operating voltages, approaching the theoretical limits, and yield small temperature coefficients. With this approach, an increasing number of groups are reporting devices with conversion efficiencies well over 20 % on n-type wafers, Panasonic leading the field with 24.7 %. Exciting results have also been obtained on p-type wafers. Despite these high voltages, important efficiency gains can still be made in fill factor and optical design. This requires improved understanding of carrier transport across device interfaces and reduced parasitic absorption in HJT solar cells. For the latter, several strategies can be followed: Short- wavelength losses can be reduced by replacing the front a-Si:H films with wider-bandgap window layers, such as silicon alloys or even metal oxides. Long-wavelength losses are mitigated by introducing new high-mobility TCO’s such as hydrogenated indium oxide, and also by designing new rear reflectors. Optical shadow losses caused by the front metalisation grid are significantly reduced by replacing printed silver electrodes with fine-line plated copper contacts, leading also to possible cost advantages. The ultimate approach to minimize optical losses is the implementation of back-contacted architectures, which are completely devoid of grid shadow losses and parasitic absorption in the front layers can be minimized irrespective of electrical transport requirements. The

  20. High-efficiency silicon heterojunction solar cells: Status and perspectives

    SciTech Connect

    De Wolf, S.; Geissbuehler, J.; Loper, P.; Martin de Nicholas, S.; Seif, J.; Tomasi, A.; Ballif, C.

    2015-05-11

    Silicon heterojunction technology (HJT) uses silicon thin-film deposition techniques to fabricate photovoltaic devices from mono-crystalline silicon wafers (c-Si). This enables energy-conversion efficiencies above 21 %, also at industrial-production level. In this presentation we review the present status of this technology and point out recent trends. We first discuss how the properties of thin hydrogenated amorphous silicon (a-Si:H) films can be exploited to fabricate passivating contacts, which is the key to high- efficiency HJT solar cells. Such contacts enable very high operating voltages, approaching the theoretical limits, and yield small temperature coefficients. With this approach, an increasing number of groups are reporting devices with conversion efficiencies well over 20 % on both-sides contacted n-type cells, Panasonic leading the field with 24.7 %. Exciting results have also been obtained on p-type wafers. Despite these high voltages, important efficiency gains can still be made in fill factor and optical design. This requires improved understanding of carrier transport across device interfaces and reduced parasitic absorption in HJT solar cells. For the latter, several strategies can be followed: Short-wavelength losses can be reduced by replacing the front a-Si:H films with wider-bandgap window layers, such as silicon alloys or even metal oxides. Long- wavelength losses are mitigated by introducing new high-mobility TCO’s such as hydrogenated indium oxide, and also by designing new rear reflectors. Optical shadow losses caused by the front metallization grid are significantly reduced by replacing printed silver electrodes with fine-line plated copper contacts, leading also to possible cost advantages. The ultimate approach to minimize optical losses is the implementation of back-contacted architectures, which are completely devoid of grid shadow losses and parasitic absorption in the front layers can be minimized irrespective of electrical

  1. Stratified Diffractive Optic Approach for Creating High Efficiency Gratings

    NASA Technical Reports Server (NTRS)

    Chambers, Diana M.; Nordin, Gregory P.

    1998-01-01

    Gratings with high efficiency in a single diffracted order can be realized with both volume holographic and diffractive optical elements. However, each method has limitations that restrict the applications in which they can be used. For example, high efficiency volume holographic gratings require an appropriate combination of thickness and permittivity modulation throughout the bulk of the material. Possible combinations of those two characteristics are limited by properties of currently available materials, thus restricting the range of applications for volume holographic gratings. Efficiency of a diffractive optic grating is dependent on its approximation of an ideal analog profile using discrete features. The size of constituent features and, consequently, the number that can be used within a required grating period restricts the applications in which diffractive optic gratings can be used. These limitations imply that there are applications which cannot be addressed by either technology. In this paper we propose to address a number of applications in this category with a new method of creating high efficiency gratings which we call stratified diffractive optic gratings. In this approach diffractive optic techniques are used to create an optical structure that emulates volume grating behavior. To illustrate the stratified diffractive optic grating concept we consider a specific application, a scanner for a space-based coherent wind lidar, with requirements that would be difficult to meet by either volume holographic or diffractive optic methods. The lidar instrument design specifies a transmissive scanner element with the input beam normally incident and the exiting beam deflected at a fixed angle from the optical axis. The element will be rotated about the optical axis to produce a conical scan pattern. The wavelength of the incident beam is 2.06 microns and the required deflection angle is 30 degrees, implying a grating period of approximately 4 microns

  2. THE NATURE OF FOSSIL GALAXY GROUPS: ARE THEY REALLY FOSSILS?

    SciTech Connect

    La Barbera, F.; Sorrentino, G.; De Carvalho, R. R.; De la Rosa, I. G.; Gal, R. R.; Kohl-Moreira, J. L.

    2009-04-15

    We use SDSS-DR4 photometric and spectroscopic data out to redshift z {approx} 0.1 combined with ROSAT All Sky Survey X-ray data to produce a sample of 25 fossil groups (FGs), defined as bound systems dominated by a single, luminous elliptical galaxy with extended X-ray emission. We examine possible biases introduced by varying the parameters used to define the sample, and the main pitfalls are also discussed. The spatial density of FGs, estimated via the V/V {sub MAX} test, is 2.83 x 10{sup -6} h {sup 3} {sub 75} Mpc{sup -3} for L{sub X} > 0.89 x 10{sup 42} h {sup -2} {sub 75} erg s{sup -1} consistent with Vikhlinin et al., who examined an X-ray overluminous elliptical galaxy sample (OLEG). We compare the general properties of FGs identified here with a sample of bright field ellipticals generated from the same data set. These two samples show no differences in the distribution of neighboring faint galaxy density excess, distance from the red sequence in the color-magnitude diagram, and structural parameters such as a {sub 4} and internal color gradients. Furthermore, examination of stellar populations shows that our 25 FGs have similar ages, metallicities, and {alpha}-enhancement as the bright field ellipticals, undermining the idea that these systems represent fossils of a physical mechanism that occurred at high redshift. Our study reveals no difference between FGs and field ellipticals, suggesting that FGs might not be a distinct family of true fossils, but rather the final stage of mass assembly in the universe.

  3. The largest fossil rodent

    PubMed Central

    Rinderknecht, Andrés; Blanco, R. Ernesto

    2008-01-01

    The discovery of an exceptionally well-preserved skull permits the description of the new South American fossil species of the rodent, Josephoartigasia monesi sp. nov. (family: Dinomyidae; Rodentia: Hystricognathi: Caviomorpha). This species with estimated body mass of nearly 1000 kg is the largest yet recorded. The skull sheds new light on the anatomy of the extinct giant rodents of the Dinomyidae, which are known mostly from isolated teeth and incomplete mandible remains. The fossil derives from San José Formation, Uruguay, usually assigned to the Pliocene–Pleistocene (4–2 Myr ago), and the proposed palaeoenvironment where this rodent lived was characterized as an estuarine or deltaic system with forest communities. PMID:18198140

  4. The largest fossil rodent.

    PubMed

    Rinderknecht, Andrés; Blanco, R Ernesto

    2008-04-22

    The discovery of an exceptionally well-preserved skull permits the description of the new South American fossil species of the rodent, Josephoartigasia monesi sp. nov. (family: Dinomyidae; Rodentia: Hystricognathi: Caviomorpha). This species with estimated body mass of nearly 1000kg is the largest yet recorded. The skull sheds new light on the anatomy of the extinct giant rodents of the Dinomyidae, which are known mostly from isolated teeth and incomplete mandible remains. The fossil derives from San José Formation, Uruguay, usually assigned to the Pliocene-Pleistocene (4-2Myr ago), and the proposed palaeoenvironment where this rodent lived was characterized as an estuarine or deltaic system with forest communities.

  5. A high efficiency cloning and expression system for proteomic analysis.

    PubMed

    Ding, Xuan Z; Paulsen, Ian T; Bhattacharjee, Apurba K; Nikolich, Mikeljon P; Myers, Gary; Hoover, David L

    2006-07-01

    The recent description of the complete genomes of the two most pathogenic species of Brucella opens the way for genome-based analysis of the antigenicity of their proteins. In the present report, we describe a bench-level high-efficiency cloning and expression system (HECES) that allow expression of large numbers of Brucella proteins based on genomic sequence information. Purified proteins are produced with high efficiency in a microarray format conducive to analysis of their sero-reactivity against serum from immunized animals. This method is applicable at either small or large scale of protein processing. While it does not require robotics, the format is amenable to robotic implementation for all aspects of the process and subsequent analysis of protein characteristics. This method will allow selection of new reagents for diagnosis of brucellosis and development of vaccine against Brucella, an important zoonotic disease and biothreat agent.

  6. The high efficiency steel filters for nuclear air cleaning

    SciTech Connect

    Bergman, W.; Larsen, G.; Lopez, R.; Williams, K.; Violet, C.

    1990-08-01

    We have, in cooperation with industry, developed high-efficiency filters made from sintered stainless-steel fibers for use in several air-cleaning applications in the nuclear industry. These filters were developed to overcome the failure modes in present high-efficiency particulate air (HEPA) filters. HEPA filters are made from glass paper and glue, and they may fail when they get hot or wet and when they are overpressured. In developing our steel filters, we first evaluated the commercially available stainless-steel filter media made from sintered powder and sintered fiber. The sintered-fiber media performed much better than sintered-powder media, and the best media had the smallest fiber diameter. Using the best media, we then built prototype filters for venting compressed gases and evaluated them in our automated filter tester. 12 refs., 20 figs.

  7. 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.

  8. Development of high-efficiency solar cells on silicon web

    NASA Technical Reports Server (NTRS)

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

    1986-01-01

    Work is reported aimed at identifying and reducing sources of carrier recombination both in the starting web silicon material and in the processed cells. Cross-sectional transmission electron microscopy measurements of several web cells were made and analyzed. The effect of the heavily twinned region on cell efficiency was modeled, and the modeling results compared to measured values for processed cells. The effects of low energy, high dose hydrogen ion implantation on cell efficiency and diffusion length were examined. Cells were fabricated from web silicon known to have a high diffusion length, with a new double layer antireflection coating being applied to these cells. A new contact system, to be used with oxide passivated cells and which greatly reduces the area of contact between metal and silicon, was designed. The application of DLTS measurements to beveled samples was further investigated.

  9. Highly Efficient Perovskite Solar Cells with Tunable Structural Color

    PubMed Central

    2015-01-01

    The performance of perovskite solar cells has been progressing over the past few years and efficiency is likely to continue to increase. However, a negative aspect for the integration of perovskite solar cells in the built environment is that the color gamut available in these materials is very limited and does not cover the green-to-blue region of the visible spectrum, which has been a big selling point for organic photovoltaics. Here, we integrate a porous photonic crystal (PC) scaffold within the photoactive layer of an opaque perovskite solar cell following a bottom-up approach employing inexpensive and scalable liquid processing techniques. The photovoltaic devices presented herein show high efficiency with tunable color across the visible spectrum. This now imbues the perovskite solar cells with highly desirable properties for cladding in the built environment and encourages design of sustainable colorful buildings and iridescent electric vehicles as future power generation sources. PMID:25650872

  10. High Energy-Efficiency Retrofits to Baltimore's Row Homes

    SciTech Connect

    Chalk, J.; Johnson, A.L.; Lipscomb, L.; Wendt, R.

    1999-04-19

    The purpose of the research project is to develop high-perfommnce, energy-eflicient retrofits of existing row homes in Baltimore, Maryland. These efficiency enhancements are to optimize building envelope improvements, mechanical equipment improvements and operational improvements to the highest cost-effective level. Furthermore, this project is to investigate and demonstrate the impact of high-performance energy-efficiency retrofit improvements on row homes in the Historic East area of Baltimore. Three homes awaiting renovation are planned to receive building envelope, mechanical system, and electrical system improvements that will improve their energy petiormance. An incremental additional cost ceiling of $4000 for the energy eftlciency improvements, beyond those normally installed, has been set by the project.

  11. High-efficiency reconciliation for continuous variable quantum key distribution

    NASA Astrophysics Data System (ADS)

    Bai, Zengliang; Yang, Shenshen; Li, Yongmin

    2017-04-01

    Quantum key distribution (QKD) is the most mature application of quantum information technology. Information reconciliation is a crucial step in QKD and significantly affects the final secret key rates shared between two legitimate parties. We analyze and compare various construction methods of low-density parity-check (LDPC) codes and design high-performance irregular LDPC codes with a block length of 106. Starting from these good codes and exploiting the slice reconciliation technique based on multilevel coding and multistage decoding, we realize high-efficiency Gaussian key reconciliation with efficiency higher than 95% for signal-to-noise ratios above 1. Our demonstrated method can be readily applied in continuous variable QKD.

  12. Cryogenic performance of high-efficiency germanium immersion grating

    NASA Astrophysics Data System (ADS)

    Sarugaku, Yuki; Ikeda, Yuji; Kaji, Sayumi; Kobayashi, Naoto; Sukegawa, Takashi; Arasaki, Takayuki; Kondo, Sohei; Nakanishi, Kenshi; Yasui, Chikako; Kawakita, Hideyo

    2016-08-01

    Immersion gratings will play important roles for infrared astronomy in the next generation. We have been developing immersion gratings with a variety of kinds of materials and have succeeded in fabricating a high-efficiency germanium (Ge) immersion grating with both a reflection coating on the grating surface and an AR coating on the entrance surface. The grating will be installed in a K-, L-, and M-bands (2-5μm) high-resolution (R=80,000) spectrograph, VINROUGE, which is a prototype for the TMT MIR instrument. In this paper, we report the preliminary results on the evaluation of the Ge immersion grating. We confirmed that the peak absolute diffraction efficiency was in the range of 70-80%, which was as expected from the design, at both room and cryogenic temperatures.

  13. High resolution PET breast imager with improved detection efficiency

    DOEpatents

    Majewski, Stanislaw

    2010-06-08

    A highly efficient PET breast imager for detecting lesions in the entire breast including those located close to the patient's chest wall. The breast imager includes a ring of imaging modules surrounding the imaged breast. Each imaging module includes a slant imaging light guide inserted between a gamma radiation sensor and a photodetector. The slant light guide permits the gamma radiation sensors to be placed in close proximity to the skin of the chest wall thereby extending the sensitive region of the imager to the base of the breast. Several types of photodetectors are proposed for use in the detector modules, with compact silicon photomultipliers as the preferred choice, due to its high compactness. The geometry of the detector heads and the arrangement of the detector ring significantly reduce dead regions thereby improving detection efficiency for lesions located close to the chest wall.

  14. Highly efficient perovskite solar cells with tunable structural color.

    PubMed

    Zhang, Wei; Anaya, Miguel; Lozano, Gabriel; Calvo, Mauricio E; Johnston, Michael B; Míguez, Hernán; Snaith, Henry J

    2015-03-11

    The performance of perovskite solar cells has been progressing over the past few years and efficiency is likely to continue to increase. However, a negative aspect for the integration of perovskite solar cells in the built environment is that the color gamut available in these materials is very limited and does not cover the green-to-blue region of the visible spectrum, which has been a big selling point for organic photovoltaics. Here, we integrate a porous photonic crystal (PC) scaffold within the photoactive layer of an opaque perovskite solar cell following a bottom-up approach employing inexpensive and scalable liquid processing techniques. The photovoltaic devices presented herein show high efficiency with tunable color across the visible spectrum. This now imbues the perovskite solar cells with highly desirable properties for cladding in the built environment and encourages design of sustainable colorful buildings and iridescent electric vehicles as future power generation sources.

  15. High-Efficiency Solar Cell Concepts: Physics, Materials, and Devices

    SciTech Connect

    Mascarenhas, A.; Francoeur, S.; Seong, M. J.; Fluegel, B.; Zhang, Y.; Wanlass, M. W.

    2005-01-01

    Over the past three decades, significant progress has been made in the area of high-efficiency multijunction solar cells, with the effort primarily directed at current-matched solar cells in tandem. The key materials issues here have been obtaining semiconductors with the required bandgaps for sequential absorption of light in the solar spectrum and that are lattice matched to readily available substrates. The GaInP/GaAs/Ge cell is a striking example of success achieved in this area. Recently, several new approaches for high-efficiency solar cell design have emerged, that involve novel methods for tailoring alloy bandgaps, as well as alternate technologies for hetero-epitaxy of III-V's on Si. The advantages and difficulties expected to be encountered with each approach will be discussed, addressing both the materials issues and device physics whilst contrasting them with other fourth-generation solar cell concepts.

  16. High efficiency thin-film GaAs solar cells

    NASA Technical Reports Server (NTRS)

    Zwerdling, S.; Wang, K. L.; Yeh, Y. C. M.

    1981-01-01

    The paper demonstrates the feasibility of producing high-efficiency GaAs solar cells with high power-to-weight ratios by organic metallic chemical vapor deposition (OM-CVD) growth of thin epi-layers on suitable substrates. An AM1 conversion efficiency of 18% (14% AM0), or 17% (13% AM0) with a 5% grid coverage is achieved for a single-crystal GaAs n(+)/p cell grown by OM-CVD on a Ge wafer. Thin GaAs epi-layers OM-CVD grown can be fabricated with good crystallographic quality using a Si-substrate on which a thin Ge epi-interlayer is first deposited by CVD from GeH4 and processed for improved surface morphology

  17. Buffer layer optimization for high efficiency CIGS solar cells

    NASA Astrophysics Data System (ADS)

    Severino, N.; Bednar, N.; Adamovic, N.

    2016-10-01

    This work presents a study concerning the numerical optimization of a buffer layer for high efficiency CIGS solar cells. The dependence of the solar cell properties on the buffer layer material, the layer thickness, the type and density of defects within the same layer were numerically investigated and analysed. Promising results were obtained with alternative Cd-free buffer layers (ZnSnO, InS and ZnS) in place of the standard CdS.

  18. Novel bipolar bathophenanthroline containing hosts for highly efficient phosphorescent OLEDs.

    PubMed

    Ge, Ziyi; Hayakawa, Teruaki; Ando, Shinji; Ueda, Mitsuru; Akiike, Toshiyuki; Miyamoto, Hidetoshi; Kajita, Toru; Kakimoto, Masa-aki

    2008-02-07

    The electronic structures of eight bathophenanthroline derivatives were elucidated by DFT calculations, and four representatives of which CZBP, m-CZBP, m-TPAP, and BPABP were synthesized and employed as the hosts to afford highly efficient phosphorescent OLEDs. The calculated molecular orbital energies agree well with the experimental results, which further demonstrates that the localization of HOMO and LUMO at the respective hole- and electron-transporting moieties is desirable in bipolar molecular designs.

  19. 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.

  20. A High Efficiency Cloning and Expression System for Proteomic Analysis

    DTIC Science & Technology

    2006-03-19

    Research, Rockville, MD, USA 0 U.a . The recent description of the complete genomes of the two most pathogenic species of Brucella Received: Januarp9...level high-efficiency cloning and expression system (HECES) that Accepted: March 19, 2006 allow expression of large numbers of Brucella proteins based...method will allow selection of new reagents for diagnosis of bru- cellosis and development of vaccine against Brucella , an important zoonotic disease and

  1. Highly efficient electron vortex beams generated by nanofabricated phase holograms

    SciTech Connect

    Grillo, Vincenzo; Mafakheri, Erfan; Frabboni, Stefano

    2014-01-27

    We propose an improved type of holographic-plate suitable for the shaping of electron beams. The plate is fabricated by a focused ion beam on a silicon nitride membrane and introduces a controllable phase shift to the electron wavefunction. We adopted the optimal blazed-profile design for the phase hologram, which results in the generation of highly efficient (25%) electron vortex beams. This approach paves the route towards applications in nano-scale imaging and materials science.

  2. 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.

  3. Efficient Hole-Transporting Materials with Triazole Core for High-Efficiency Perovskite Solar Cells.

    PubMed

    Choi, Hyeju; Jo, Hyeonjun; Paek, Sanghyun; Koh, Kyungkuk; Ko, Haye Min; Lee, Jae Kwan; Ko, Jaejung

    2016-02-18

    Efficient hole-transporting materials (HTMs), TAZ-[MeOTPA]2 and TAZ-[MeOTPATh]2 incorporating two electron-rich diphenylamino side arms, through direct linkage or thiophen bridges, respectively, on the C3- and C5-positions of a 4-phenyl-1,2,4-triazole core were synthesized. These synthetic HTMs with donor-acceptor type molecular structures exhibited effective intramolecular charge transfer for improving the hole-transporting properties. The structural modification of HTMs by thiophene bridging might increase intermolecular π-π stacking in the solid state and afford a better spectral response because of their increased π-conjugation length. Perovskite-based cells using TAZ-[MeOTPA]2 and TAZ-[MeOTPATh]2 as HTMs afforded high power conversion efficiencies of 10.9 % and 14.4 %, respectively, showing a photovoltaic performance comparable to that obtained using spiro-OMeTAD. These synthetically simple and inexpensive HTMs hold promise for replacing the more expensive spiro-OMeTAD in high-efficiency perovskite solar cells.

  4. Porous Pd nanoparticles with high photothermal conversion efficiency for efficient ablation of cancer cells.

    PubMed

    Xiao, Jia-Wen; Fan, Shi-Xuan; Wang, Feng; Sun, Ling-Dong; Zheng, Xiao-Yu; Yan, Chun-Hua

    2014-04-21

    Nanoparticle (NP) mediated photothermal effect shows great potential as a noninvasive method for cancer therapy treatment, but the development of photothermal agents with high photothermal conversion efficiency, small size and good biocompatibility is still a big challenge. Herein, we report Pd NPs with a porous structure exhibiting enhanced near infrared (NIR) absorption as compared to Pd nanocubes with a similar size (almost two-fold enhancement with a molar extinction coefficient of 6.3 × 10(7) M(-1) cm(-1)), and the porous Pd NPs display monotonically rising absorbance from NIR to UV-Vis region. When dispersed in water and illuminated with an 808 nm laser, the porous Pd NPs give a photothermal conversion efficiency as high as 93.4%, which is comparable to the efficiency of Au nanorods we synthesized (98.6%). As the porous Pd NPs show broadband NIR absorption (650-1200 nm), this allows us to choose multiple laser wavelengths for photothermal therapy. In vitro photothermal heating of HeLa cells in the presence of porous Pd NPs leads to 100% cell death under 808 nm laser irradiation (8 W cm(-2), 4 min). For photothermal heating using 730 nm laser, 70% of HeLa cells were killed after 4 min irradiation at a relative low power density of 6 W cm(-2). These results demonstrated that the porous Pd nanostructure is an attractive photothermal agent for cancer therapy.

  5. Telescoping Solar Array Concept for Achieving High Packaging Efficiency

    NASA Technical Reports Server (NTRS)

    Mikulas, Martin; Pappa, Richard; Warren, Jay; Rose, Geoff

    2015-01-01

    Lightweight, high-efficiency solar arrays are required for future deep space missions using high-power Solar Electric Propulsion (SEP). Structural performance metrics for state-of-the art 30-50 kW flexible blanket arrays recently demonstrated in ground tests are approximately 40 kW/cu m packaging efficiency, 150 W/kg specific power, 0.1 Hz deployed stiffness, and 0.2 g deployed strength. Much larger arrays with up to a megawatt or more of power and improved packaging and specific power are of interest to mission planners for minimizing launch and life cycle costs of Mars exploration. A new concept referred to as the Compact Telescoping Array (CTA) with 60 kW/cu m packaging efficiency at 1 MW of power is described herein. Performance metrics as a function of array size and corresponding power level are derived analytically and validated by finite element analysis. Feasible CTA packaging and deployment approaches are also described. The CTA was developed, in part, to serve as a NASA reference solar array concept against which other proposed designs of 50-1000 kW arrays for future high-power SEP missions could be compared.

  6. Flexible, highly efficient all-polymer solar cells.

    PubMed

    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

    2015-10-09

    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.

  7. 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

  8. Fuel Cell/Turbine Ultra High Efficiency Power System

    SciTech Connect

    Hossein, Ghezel-Ayagh

    2001-11-06

    FuelCell Energy, INC. (FCE) is currently involved in the design of ultra high efficiency power plants under a cooperative agreement (DE-FC26-00NT40) managed by the National Energy Technology Laboratory (NETL) as part of the DOE's Vision 21 program. Under this project, FCE is developing a fuel cell/turbine hybrid system that integrates the atmospheric pressure Direct FuelCell{reg_sign} (DFC{reg_sign}) with an unfired Brayton cycle utilizing indirect heat recovery from the power plant. Features of the DFC/T{trademark} system include: high efficiency, minimal emissions, simplicity in design, direct reforming internal to the fuel cell, no pressurization of the fuel cell, independent operating pressure of the fuel cell and turbine, and potential cost competitiveness with existing combined cycle power plants at much smaller sizes. Objectives of the Vision 21 Program include developing power plants that will generate electricity with net efficiencies approaching 75 percent (with natural gas), while producing sulfur and nitrogen oxide emissions of less than 0.01 lb/million BTU. These goals are significant improvements over conventional power plants, which are 35-60 percent efficient and produce emissions of 0.07 to 0.3 lb/million BTU of sulfur and nitrogen oxides. The nitrogen oxide and sulfur emissions from the DFC/T system are anticipated to be better than the Vision 21 goals due to the non-combustion features of the DFC/T power plant. The expected high efficiency of the DFC/T will also result in a 40-50 percent reduction in carbon dioxide emissions compared to conventional power plants. To date, the R&D efforts have resulted in significant progress including proof-of-concept tests of a sub-scale power plant built around a state-of-the-art DFC stack integrated with a modified Capstone Model 330 Microturbine. The objectives of this effort are to investigate the integration aspects of the fuel cell and turbine and to obtain design information and operational data that will

  9. Development and evaluation of a cleanable high efficiency steel filter

    SciTech Connect

    Bergman, W.; Larsen, G.; Weber, F.; Wilson, P.; Lopez, R.; Valha, G.; Conner, J.; Garr, J.; Williams, K.; Biermann, A.; Wilson, K.; Moore, P.; Gellner, C.; Rapchun, D. ); Simon, K.; Turley, J.; Frye, L.; Monroe, D. )

    1993-01-01

    We have developed a high efficiency steel filter that can be cleaned in-situ by reverse air pulses. The filter consists of 64 pleated cylindrical filter elements packaged into a 6l0 [times] 6l0 [times] 292 mm aluminum frame and has 13.5 m[sup 2] of filter area. The filter media consists of a sintered steel fiber mat using 2 [mu]m diameter fibers. We conducted an optimization study for filter efficiency and pressure drop to determine the filter design parameters of pleat width, pleat depth, outside diameter of the cylinder, and the total number of cylinders. Several prototype cylinders were then built and evaluated in terms of filter cleaning by reverse air pulses. The results of these studies were used to build the high efficiency steel filter. We evaluated the prototype filter for efficiency and cleanability. The DOP filter certification test showed the filter has a passing efficiency of 99.99% but a failing pressure drop of 0.80 kPa at 1,700 m[sup 3]/hr. Since we were not able to achieve a pressure drop less than 0.25 kPa, the steel filter does not meet all the criteria for a HEPA filter. Filter loading and cleaning tests using AC Fine dust showed the filter could be repeatedly cleaned by reverse air pulses. The next phase of the prototype evaluation consisted of installing the unit and support housing in the exhaust duct work of a uranium grit blaster for a field evaluation at the Y-12 Plant in Oak Ridge, TN. The grit blaster is used to clean the surface of uranium parts and generates a cloud of UO[sub 2] aerosols. We used a 1,700 m[sup 3]/hr slip stream from the 10,200 m[sup 3]/hr exhaust system.

  10. Development and evaluation of a cleanable high efficiency steel filter

    SciTech Connect

    Bergman, W.; Larsen, G.; Weber, F.; Wilson, P.; Lopez, R.; Valha, G.; Conner, J.; Garr, J.; Williams, K.; Biermann, A.; Wilson, K.; Moore, P.; Gellner, C.; Rapchun, D.; Simon, K.; Turley, J.; Frye, L.; Monroe, D.

    1993-01-01

    We have developed a high efficiency steel filter that can be cleaned in-situ by reverse air pulses. The filter consists of 64 pleated cylindrical filter elements packaged into a 6l0 {times} 6l0 {times} 292 mm aluminum frame and has 13.5 m{sup 2} of filter area. The filter media consists of a sintered steel fiber mat using 2 {mu}m diameter fibers. We conducted an optimization study for filter efficiency and pressure drop to determine the filter design parameters of pleat width, pleat depth, outside diameter of the cylinder, and the total number of cylinders. Several prototype cylinders were then built and evaluated in terms of filter cleaning by reverse air pulses. The results of these studies were used to build the high efficiency steel filter. We evaluated the prototype filter for efficiency and cleanability. The DOP filter certification test showed the filter has a passing efficiency of 99.99% but a failing pressure drop of 0.80 kPa at 1,700 m{sup 3}/hr. Since we were not able to achieve a pressure drop less than 0.25 kPa, the steel filter does not meet all the criteria for a HEPA filter. Filter loading and cleaning tests using AC Fine dust showed the filter could be repeatedly cleaned by reverse air pulses. The next phase of the prototype evaluation consisted of installing the unit and support housing in the exhaust duct work of a uranium grit blaster for a field evaluation at the Y-12 Plant in Oak Ridge, TN. The grit blaster is used to clean the surface of uranium parts and generates a cloud of UO{sub 2} aerosols. We used a 1,700 m{sup 3}/hr slip stream from the 10,200 m{sup 3}/hr exhaust system.

  11. Highly Efficient Segmented p-type Thermoelectric Leg

    NASA Astrophysics Data System (ADS)

    Sadia, Yatir; Ben-Yehuda, Ohad; Gelbstein, Yaniv

    In the past years, energy demands in the entire world have been constantly increasing. This fact, coupled with the requirement for decreasing the world's dependence on fossil fuels, has given rise to the need for alternative energy sources. While no single alternative energy source can solely replace the traditional fossil fuels, the combination of several alternative power sources can greatly decrease their usage. Thermoelectricity is one way to produce such energy via the harvesting of waste heat into electricity. One common example is the automobile industry which in the past few years had been looking into the option of harvesting the waste heat created by the engine, around the exhaust pipe and in the catalytic converter. Thermoelectricity is ideal for such application since it can convert the energy directly into electric current without any moving parts, thereby extending the life cycle of the operation.

  12. High-Efficiency Absorber for Damping the Transverse Wake Fields

    SciTech Connect

    Novokhatski, A.; Seeman, J.; Weathersby, S.; /SLAC

    2007-02-28

    Transverse wake fields generated by intense beams may propagate long distances in the vacuum chamber and dissipate power in different shielded elements such as bellows, vacuum valves or vacuum pumps. Induced heating in these elements may be high enough to deteriorate vacuum conditions. We have developed a broadband water-cooled bellows-absorber to capture and damp these harmful transverse fields without impacting the longitudinal beam impedance. Experimental results at the PEP-II SLAC B-factory demonstrate high efficiency of this device. This absorber may be useful in other machines like synchrotron light sources or International Linear Collider.

  13. High efficiency, low cost thin GaAs solar cells

    NASA Technical Reports Server (NTRS)

    Fan, J. C. C.

    1982-01-01

    The feasibility of fabricating space-resistant, high efficiency, light-weight, low-cost GaAs shallow-homojunction solar cells for space application is demonstrated. This program addressed the optimal preparation of ultrathin GaAs single-crystal layers by AsCl3-GaAs-H2 and OMCVD process. Considerable progress has been made in both areas. Detailed studies on the AsCl3 process showed high-quality GaAs thin layers can be routinely grown. Later overgrowth of GaAs by OMCVD has been also observed and thin FaAs films were obtained from this process.

  14. Efficiency of nonstandard and high contact ratio involute spur gears

    NASA Technical Reports Server (NTRS)

    Anderson, N. E.; Loewenthal, S. H.

    1984-01-01

    A power loss prediction was extended to include involute spur gears of nonstandard proportions. The method is used to analyze the effects of modified addendum, tooth thickness, and gear center distance in addition to the parameters previously considered which included gear diameter, pitch, pressure angle, face width, oil viscosity, speed, and torque. Particular emphasis was placed on high contact ratio gearing (contact ratios greater than two). Despite their higher sliding velocities, high contact ratio gears are designed to levels of efficiency comparable to those of conventional gears while retaining their advantages through proper selection of gear geometry.

  15. Efficiency of nonstandard and high contact ratio involute spur gears

    NASA Technical Reports Server (NTRS)

    Anderson, N. E.; Loewenthal, S. H.

    1986-01-01

    A power loss prediction was extended to include involute spur gears of nonstandard proportions. The method is used to analyze the effects of modified addendum, tooth thickness, and gear center distance in addition to the parameters previously considered which included gear diameter, pitch, pressure angle, face width, oil viscosity, speed, and torque. Particular emphasis was placed on high contact ratio gearing (contact ratios greater than two). Despite their higher sliding velocities, high contact ratio gears are designed to levels of efficiency comparable to those of conventional gears while retaining their advantages through proper selection of gear geometry.

  16. High efficiency CIP 10-I personal inhalable aerosol sampler

    NASA Astrophysics Data System (ADS)

    Görner, P.; Wrobel, R.; Simon, X.

    2009-02-01

    The CIP 10 personal aerosol sampler was first developed by Courbon for sampling the respirable fraction of mining dust. This respirable aerosol sampler was further improved by Fabries, then selectors for sampling thoracic and inhalable aerosols were designed. Kenny et al. evaluated the particle-size dependent sampling efficiency of the inhalable version in a large-scale wind tunnel using a life-size dummy. The authors found that the overall sampling efficiency decreases more rapidly than the CEN-ISO-ACGIH target efficiency curve. Görner and Witschger measured the aspiration efficiency of the CIP 10 omni-directional inlet. They found that the aspiration efficiency was high enough for inhalable aerosol sampling. This result led to the conclusion that the low sampling efficiency is due to some internal losses of the aspirated particles before they reach the final sampling stage, namely the CIP 10 rotating filter. Based on the assumption that the inhalable particles are selected at selector aspiration level, an experimental research project was conducted to improve particle transmission to the collection stage of the sampler. Two different inhalable selectors were designed by Görner and tested in a laboratory wind tunnel. The transmission efficiency of both models was measured by Roger following an experimental protocol described by Witschger. The T-shaped air flow circuit was finally adopted to draw the aspirated particles into the final collection stage of the CIP 10. Actually, in this selector, the almost horizontally aspirated particles should be conducted vertically to the rotating cup. In two previous prototypes, particles could be deposited in certain places by inertia (where the aerosol was forced to deviate drastically) or by sedimentation (where the aerosol decelerated). The aerodynamic behaviour of the adopted solution causes the particles to accelerate radially between two horizontal plates before they enter a vertical tube. This acceleration avoids the

  17. Evaluation of Parameters for High Efficiency Transformation of Acinetobacter baumannii

    PubMed Central

    Yildirim, Suleyman; Thompson, Mitchell G.; Jacobs, Anna C.; Zurawski, Daniel V.; Kirkup, Benjamin C.

    2016-01-01

    Acinetobacter baumannii is an emerging, nosocomial pathogen that is poorly characterized due to a paucity of genetic tools and methods. While whole genome sequence data from several epidemic and environmental strains have recently become available, the functional characterization of genes is significantly lagging. Efficient transformation is one of the first steps to develop molecular tools that can be used to address these shortcomings. Here we report parameters allowing high efficiency transformation of A. baumannii. Using a multi-factorial experimental design we found that growth phase, voltage, and resistance all significantly contribute to transformation efficiency. The highest efficiency (4.3 × 108 Transformants/μg DNA) was obtained at the stationary growth phase of the bacterium (OD 6.0) using 25 ng of plasmid DNA under 100 Ohms resistance and 1.7 kV/cm voltage. The optimized electroporation parameters reported here provide a useful tool for genetic manipulation of A. baumannii. PMID:26911658

  18. IN-PLANT TESTING OF HIGH-EFFICIENCY HYDRAULIC SEPARATORS

    SciTech Connect

    G.H. Luttrell; R.Q. Honaker; R.C. Bratton; T.C. Westerfield; J.N. Kohmuench

    2006-05-22

    Hydraulic separators are commonly used for particle size classification and gravity concentration of minerals and coal. Unfortunately, the efficiency of these processes can be quite low due to poor equipment design and variations in feed consistency. To help alleviate these problems, an industry-driven R&D program has been undertaken to develop a new generation of hydraulic separators that are more efficient and less costly to operate and maintain. These units, which are commercially called the CrossFlow separator and HydroFloat separator, have the potential to improve performance (separation efficiency and throughput) and reduce operating costs (power consumption, water and reagent usage). In Phase I of this project, laboratory and pilot-scale test units were evaluated at various industrial sites in both the coal and mineral industries. Based on promising results obtained from Phase I, full-scale prototypes were purchased and installed by a major U.S. phosphate producer and a large eastern U.S. coal company. The test data obtained from these sites demonstrate that significant performance improvements can be realized through the application of these high-efficiency separators.

  19. In-Plant Testing of High-Efficiency Hydraulic Separators

    SciTech Connect

    G. H. Luttrell; R. Q. Honaker; R. C. Bratton; T. C. Westerfield; J. N. Kohmuench

    2006-06-30

    Hydraulic separators are commonly used for particle size classification and gravity concentration of minerals and coal. Unfortunately, the efficiency of these processes can be quite low due to poor equipment design and variations in feed consistency. To help alleviate these problems, an industry-driven R&D program has been undertaken to develop a new generation of hydraulic separators that are more efficient and less costly to operate and maintain. These units, which are commercially called the CrossFlow separator and HydroFloat separator, have the potential to improve performance (separation efficiency and throughput) and reduce operating costs (power consumption, water and reagent usage). In Phase I of this project, laboratory and pilot-scale test units were evaluated at various industrial sites in both the coal and mineral industries. Based on promising results obtained from Phase I, full-scale prototypes were purchased and installed by a major U.S. phosphate producer and a large eastern U.S. coal company. The test data obtained from these sites demonstrate that significant performance improvements can be realized through the application of these high-efficiency separators.

  20. A high efficiency LED driver based on optical feedback

    NASA Astrophysics Data System (ADS)

    Marti-Arbona, Edgar; Copani, Tino; Bakkaloglu, Bertan; Kiaei, Sayfe

    2014-09-01

    Light emitting diodes (LEDs) offer durability, long life, and high efficiency that make them an excellent alternative for illumination applications. The efficiency of conventional drivers suffers from losses due to the current sensing method that they employ. In this paper, the LED array itself is used as an optical sensor by periodically measuring neighboring cells' light intensity, instead of employing the commonly used series current-sense resistor. The results of this approach show that it provides accurate compensation of the LED characteristics, with less than one lumen variation in illumination, stability in color (color shift over time as low as ΔE = 0.76), and efficiency of up to 98.66%. The proposed sensor compensates for actual optical performance of the LED array and reduces aging effects compared to the approaches based in current measurement and control. The optical current-sensing method is a closed-loop feedback alternative, which improves the power efficiency of the LED driver by 3%. It maintains constant output illumination of the LED over time, and it utilizes a reduced number of components, thus extending the effective lifetime of LED-based devices.

  1. Analysis of high efficiency back point contact silicon solar cells

    NASA Astrophysics Data System (ADS)

    Luque, Antonio

    1988-01-01

    A model has been developed for the analysis of Back Point-Contact (BPC) cells under variable injection level. The analysis has been applied to an experimental cell from Stanford University to allow the extraction of the recombination parameters of this cell. While the bulk SRH recombination and the recombination in the surface and in the emitters are those expected, the Auger constant takes a higher value (2.1 × 10 -30 cm 6/s), than the one usually accepted, and in agreement with the measurements by the Stanford group, for the carrier density involved here. The analysis indicates that best efficiency results are obtained with cells with finely designed emitter dots and well passivated surfaces, made on high resistivity substrates, leading to an upper limit of efficiency obtained at 20 W/cm 2 of about 30.4%. If our technology prevents us from a fine dot delineation (below 5-10 μm) then the highest efficiency is to be expected from the more conventional Interdigitated Back Contact cells with a limit (with our fitted Auger constant) of about 30%. Finally, if the commonly accepted value of the Auger constant (3.8 × 10 -31 cm 6/s) is used this limit is obtained at 50 W/cm 2 and is of 33.1% with a strongly idealized cell. All the efficiencies are at 25°C.

  2. Recombination phenomena in high efficiency silicon solar cells

    NASA Technical Reports Server (NTRS)

    Sah, C. T.

    1985-01-01

    The dominant recombination phenomena which limit the highest efficiency attainable in silicon solar cells under terrestrial sunlight are reviewed. The ultimate achievable efficiency is limited by the two intrinsic recombination mechanisms, the interband Auger recombination and interband Radiative recombination, both of which occur in the entire cell body but principally in the base layer. It is suggested that an optimum (26%) cell design is one with lowly doped 50 to 100 micron thick base, a perfect BSF, and zero extrinsic recombination such as the thermal mechanism at recombination centers the Shockley-Read-Hall process (SRH) in the bulk, on the surface and at the interfaces. The importance of recombination at the interfaces of a high-efficiency cell is demonstrated by the ohmic contact on the back surface whose interface recombination velocity is infinite. The importance of surface and interface recombination is demonstrated by representing the auger and radiative recombination losses by effective recombination velocities. It is demonstrated that the three highest efficiency cells may all be limited by the SRH recombination losses at recombination centers in the base layer.

  3. High Efficiency CVD Graphene-lead (Pb) Cooper Pair Splitter.

    PubMed

    Borzenets, I V; Shimazaki, Y; Jones, G F; Craciun, M F; Russo, S; Yamamoto, M; Tarucha, S

    2016-03-14

    Generation and manipulation of quantum entangled electrons is an important concept in quantum mechanics, and necessary for advances in quantum information processing; but not yet established in solid state systems. A promising device is a superconductor-two quantum dots Cooper pair splitter. Early nanowire based devices, while efficient, are limited in scalability and further electron manipulation. We demonstrate an optimized, high efficiency, CVD grown graphene-based Cooper pair splitter. Our device is designed to induce superconductivity in graphene via the proximity effect, resulting in both a large superconducting gap Δ = 0.5 meV, and coherence length ξ = 200 nm. The flat nature of the device lowers parasitic capacitance, increasing charging energy EC. Our design also eases geometric restrictions and minimizes output channel separation. As a result we measure a visibility of up to 86% and a splitting efficiency of up to 62%. This will pave the way towards near unity efficiencies, long distance splitting, and post-splitting electron manipulation.

  4. Recent progress of Spectrolab high-efficiency space solar cells

    NASA Astrophysics Data System (ADS)

    Law, Daniel C.; Boisvert, J. C.; Rehder, E. M.; Chiu, P. T.; Mesropian, S.; Woo, R. L.; Liu, X. Q.; Hong, W. D.; Fetzer, C. M.; Singer, S. B.; Bhusari, D. M.; Edmondson, K. M.; Zakaria, A.; Jun, B.; Krut, D. D.; King, R. R.; Sharma, S. K.; Karam, N. H.

    2013-09-01

    Recent progress in III-V multijunction space solar cell has led to Spectrolab's GaInP/GaAs/Ge triple-junction, XTJ, cells with average 1-sun efficiency of 29% (AM0, 28°C) for cell size ranging from 59 to 72-cm2. High-efficiency inverted metamorphic (IMM) multijunction cells are developed as the next space solar cell architecture. Spectrolab's large-area IMM3J and IMM4J cells have achieved 33% and 34% 1-sun, AM0 efficiencies, respectively. The IMM3J and the IMM4J cells have both demonstrated normalized power retention of 0.86 at 5x1014 e-/cm2 fluence and 0.83 and 0.82 at 1x1015 e-/cm2 fluence post 1-MeV electron radiation, respectively. The IMM cells were further assembled into coverglass-interconnect-cell (CIC) strings and affixed to typical rigid aluminum honeycomb panels for thermal cycling characterization. Preliminary temperature cycling data of two coupons populated with IMM cell strings showed no performance degradation. Spectrolab has also developed semiconductor bonded technology (SBT) where highperformance component subcells were grown on GaAs and InP substrates separately then bonded directly to form the final multijunction cells. Large-area SBT 5-junction cells have achieved a 35.1% efficiency under 1-sun, AM0 condition.

  5. High Efficiency CVD Graphene-lead (Pb) Cooper Pair Splitter

    PubMed Central

    Borzenets, I. V.; Shimazaki, Y.; Jones, G. F.; Craciun, M. F.; Russo, S.; Yamamoto, M.; Tarucha, S.

    2016-01-01

    Generation and manipulation of quantum entangled electrons is an important concept in quantum mechanics, and necessary for advances in quantum information processing; but not yet established in solid state systems. A promising device is a superconductor-two quantum dots Cooper pair splitter. Early nanowire based devices, while efficient, are limited in scalability and further electron manipulation. We demonstrate an optimized, high efficiency, CVD grown graphene-based Cooper pair splitter. Our device is designed to induce superconductivity in graphene via the proximity effect, resulting in both a large superconducting gap Δ = 0.5 meV, and coherence length ξ = 200 nm. The flat nature of the device lowers parasitic capacitance, increasing charging energy EC. Our design also eases geometric restrictions and minimizes output channel separation. As a result we measure a visibility of up to 86% and a splitting efficiency of up to 62%. This will pave the way towards near unity efficiencies, long distance splitting, and post-splitting electron manipulation. PMID:26971450

  6. High efficiency, multiterawatt x-ray free electron lasers

    NASA Astrophysics Data System (ADS)

    Emma, C.; Fang, K.; Wu, J.; Pellegrini, C.

    2016-02-01

    In this paper we present undulator magnet tapering methods for obtaining high efficiency and multiterawatt peak powers in x-ray free electron lasers (XFELs), a key requirement for enabling 3D atomic resolution single molecule imaging and nonlinear x-ray science. The peak power and efficiency of tapered XFELs is sensitive to time dependent effects, like synchrotron sideband growth. To analyze this dependence in detail we perform a comparative numerical optimization for the undulator magnetic field tapering profile including and intentionally disabling these effects. We show that the solution for the magnetic field taper profile obtained from time independent optimization does not yield the highest extraction efficiency when time dependent effects are included. Our comparative optimization is performed for a novel undulator designed specifically to obtain TW power x-ray pulses in the shortest distance: superconducting, helical, with short period and built-in strong focusing. This design reduces the length of the breaks between modules, decreasing diffraction effects, and allows using a stronger transverse electron focusing. Both effects reduce the gain length and the overall undulator length. We determine that after a fully time dependent optimization of a 100 m long Linac coherent light source-like XFEL we can obtain a maximum efficiency of 7%, corresponding to 3.7 TW peak radiation power. Possible methods to suppress the synchrotron sidebands, and further enhance the FEL peak power, up to about 6 TW by increasing the seed power and reducing the electron beam energy spread, are also discussed.

  7. Highly Efficient Thermoresponsive Nanocomposite for Controlled Release Applications

    NASA Astrophysics Data System (ADS)

    Yassine, Omar; Zaher, Amir; Li, Er Qiang; Alfadhel, Ahmed; Perez, Jose E.; Kavaldzhiev, Mincho; Contreras, Maria F.; Thoroddsen, Sigurdur T.; Khashab, Niveen M.; Kosel, Jurgen

    2016-06-01

    Highly efficient magnetic release from nanocomposite microparticles is shown, which are made of Poly (N-isopropylacrylamide) hydrogel with embedded iron nanowires. A simple microfluidic technique was adopted to fabricate the microparticles with a high control of the nanowire concentration and in a relatively short time compared to chemical synthesis methods. The thermoresponsive microparticles were used for the remotely triggered release of Rhodamine (B). With a magnetic field of only 1 mT and 20 kHz a drug release of 6.5% and 70% was achieved in the continuous and pulsatile modes, respectively. Those release values are similar to the ones commonly obtained using superparamagnetic beads but accomplished with a magnetic field of five orders of magnitude lower power. The high efficiency is a result of the high remanent magnetization of the nanowires, which produce a large torque when exposed to a magnetic field. This causes the nanowires to vibrate, resulting in friction losses and heating. For comparison, microparticles with superparamagnetic beads were also fabricated and tested; while those worked at 73 mT and 600 kHz, no release was observed at the low field conditions. Cytotoxicity assays showed similar and high cell viability for microparticles with nanowires and beads.

  8. Highly Efficient Thermoresponsive Nanocomposite for Controlled Release Applications

    PubMed Central

    Yassine, Omar; Zaher, Amir; Li, Er Qiang; Alfadhel, Ahmed; Perez, Jose E.; Kavaldzhiev, Mincho; Contreras, Maria F.; Thoroddsen, Sigurdur T.; Khashab, Niveen M.; Kosel, Jurgen

    2016-01-01

    Highly efficient magnetic release from nanocomposite microparticles is shown, which are made of Poly (N-isopropylacrylamide) hydrogel with embedded iron nanowires. A simple microfluidic technique was adopted to fabricate the microparticles with a high control of the nanowire concentration and in a relatively short time compared to chemical synthesis methods. The thermoresponsive microparticles were used for the remotely triggered release of Rhodamine (B). With a magnetic field of only 1 mT and 20 kHz a drug release of 6.5% and 70% was achieved in the continuous and pulsatile modes, respectively. Those release values are similar to the ones commonly obtained using superparamagnetic beads but accomplished with a magnetic field of five orders of magnitude lower power. The high efficiency is a result of the high remanent magnetization of the nanowires, which produce a large torque when exposed to a magnetic field. This causes the nanowires to vibrate, resulting in friction losses and heating. For comparison, microparticles with superparamagnetic beads were also fabricated and tested; while those worked at 73 mT and 600 kHz, no release was observed at the low field conditions. Cytotoxicity assays showed similar and high cell viability for microparticles with nanowires and beads. PMID:27335342

  9. 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.

  10. A robust TALENs system for highly efficient mammalian genome editing.

    PubMed

    Feng, Yuanxi; Zhang, Siliang; Huang, Xin

    2014-01-10

    Recently, transcription activator-like effector nucleases (TALENs) have emerged as a highly effective tool for genomic editing. A pair of TALENs binds to two DNA recognition sites separated by a spacer sequence, and the dimerized FokI nucleases at the C terminal then cleave DNA in the spacer. Because of its modular design and capacity to precisely target almost any desired genomic locus, TALEN is a technology that can revolutionize the entire biomedical research field. Currently, for genomic editing in cultured cells, two plasmids encoding a pair of TALENs are co-transfected, followed by limited dilution to isolate cell colonies with the intended genomic manipulation. However, uncertain transfection efficiency becomes a bottleneck, especially in hard-to-transfect cells, reducing the overall efficiency of genome editing. We have developed a robust TALENs system in which each TALEN plasmid also encodes a fluorescence protein. Thus, cells transfected with both TALEN plasmids, a prerequisite for genomic editing, can be isolated by fluorescence-activated cell sorting. Our improved TALENs system can be applied to all cultured cells to achieve highly efficient genomic editing. Furthermore, an optimized procedure for genomic editing using TALENs is also presented. We expect our system to be widely adopted by the scientific community.

  11. Highly efficient baculovirus-mediated multigene delivery in primary cells

    PubMed Central

    Mansouri, Maysam; Bellon-Echeverria, Itxaso; Rizk, Aurélien; Ehsaei, Zahra; Cianciolo Cosentino, Chiara; Silva, Catarina S.; Xie, Ye; Boyce, Frederick M.; Davis, M. Wayne; Neuhauss, Stephan C. F.; Taylor, Verdon; Ballmer-Hofer, Kurt; Berger, Imre; Berger, Philipp

    2016-01-01

    Multigene delivery and subsequent cellular expression is emerging as a key technology required in diverse research fields including, synthetic and structural biology, cellular reprogramming and functional pharmaceutical screening. Current viral delivery systems such as retro- and adenoviruses suffer from limited DNA cargo capacity, thus impeding unrestricted multigene expression. We developed MultiPrime, a modular, non-cytotoxic, non-integrating, baculovirus-based vector system expediting highly efficient transient multigene expression from a variety of promoters. MultiPrime viruses efficiently transduce a wide range of cell types, including non-dividing primary neurons and induced-pluripotent stem cells (iPS). We show that MultiPrime can be used for reprogramming, and for genome editing and engineering by CRISPR/Cas9. Moreover, we implemented dual-host-specific cassettes enabling multiprotein expression in insect and mammalian cells using a single reagent. Our experiments establish MultiPrime as a powerful and highly efficient tool, to deliver multiple genes for a wide range of applications in primary and established mammalian cells. PMID:27143231

  12. Nonstoichiometric Adduct Approach for High-Efficiency Perovskite Solar Cells.

    PubMed

    Park, Nam-Gyu

    2017-01-03

    Since the groundbreaking report on a solid-state perovskite solar cell employing a methylammonium lead iodide-sensitized mesoporous TiO2 film and an organic hole conducting layer in 2012 by our group, the swift surge of perovskite photovoltaics opens a new paradigm in solar-cell research. As a result, ca. 1300 peer-reviewed research articles were published in 2015. In this Inorganic Chemistry Forum on Halide Perovskite, the researches with highlights of work on perovskite solar cells in my laboratory are reviewed. We have developed a size-controllable two-step spin-coating method and found that minimal nonradiative recombination in perovskite crystals could lead to high photovoltaic performance. A Lewis acid based adduct method and self-formed grain boundary process were developed for high-efficiency devices with reproducibility. A power conversion efficiency of 20.4% was achieved via grain boundary engineering based on a nonstoichiometric adduct approach. The incorporation of cesium in a formamidinium lead iodide perovskite was found to show better photostability and moisture-stability. A reduction in the dimensionality from a three-dimensitonal nanocrystal to a one-dimensional nanowire led to a hypsochromic shift of absorption and fluorescence. To enhance the charge-carrier transport and light-harvesting efficiency, a nanoarchitecture of oxide layers was proposed.

  13. Highly efficient metallic optical incouplers for quantum well infrared photodetectors

    PubMed Central

    Liu, Long; Chen, Yu; Huang, Zhong; Du, Wei; Zhan, Peng; Wang, Zhenlin

    2016-01-01

    Herein, we propose a highly efficient metallic optical incoupler for a quantum well infrared photodetector (QWIP) operating in the spectrum range of 14~16 μm, which consists of an array of metal micropatches and a periodically corrugated metallic back plate sandwiching a semiconductor active layer. By exploiting the excitations of microcavity modes and hybrid spoof surface plasmons (SSPs) modes, this optical incoupler can convert infrared radiation efficiently into the quantum wells (QWs) layer of semiconductor region with large electrical field component (Ez) normal to the plane of QWs. Our further numerical simulations for optimization indicate that by tuning microcavity mode to overlap with hybrid SSPs mode in spectrum, a coupled mode is formed, which leads to 33-fold enhanced light absorption for QWs centered at wavelength of 14.5 μm compared with isotropic absorption of QWs without any metallic microstructures, as well as a large value of coupling efficiency (η) of |Ez|2 ~ 6. This coupled mode shows a slight dispersion over ~40° and weak polarization dependence, which is quite beneficial to the high performance infrared photodetectors. PMID:27456691

  14. High-efficiency generation in a short random fiber laser

    NASA Astrophysics Data System (ADS)

    Vatnik, I. D.; Churkin, D. V.; Podivilov, E. V.; Babin, S. A.

    2014-07-01

    We demonstrate a high-efficiency random lasing in a 850 m span of a phosphosilicate fiber. Random distributed feedback owing to the Rayleigh backscattering in the fiber enables narrowband generation with output power of up to 7.3 W at the Stokes wavelength λS = 1308 nm from 11 W of the pump power at λP = 1115 nm. The laser demonstrates unique generation efficiency. Near the generation threshold, more than 2 W of output power is generated from only 0.5 W of pump power excess over the generation threshold. At high pump power, the quantum conversion efficiency defined as a ratio of generated and pump photons at the laser output exceeds 100%. It is explained by the fact that every pump photon is converted into the Stokes photon far from the output fiber end, while the Stokes photons have lower attenuation than the pump photons.

  15. Highly efficient metallic optical incouplers for quantum well infrared photodetectors

    NASA Astrophysics Data System (ADS)

    Liu, Long; Chen, Yu; Huang, Zhong; Du, Wei; Zhan, Peng; Wang, Zhenlin

    2016-07-01

    Herein, we propose a highly efficient metallic optical incoupler for a quantum well infrared photodetector (QWIP) operating in the spectrum range of 14~16 μm, which consists of an array of metal micropatches and a periodically corrugated metallic back plate sandwiching a semiconductor active layer. By exploiting the excitations of microcavity modes and hybrid spoof surface plasmons (SSPs) modes, this optical incoupler can convert infrared radiation efficiently into the quantum wells (QWs) layer of semiconductor region with large electrical field component (Ez) normal to the plane of QWs. Our further numerical simulations for optimization indicate that by tuning microcavity mode to overlap with hybrid SSPs mode in spectrum, a coupled mode is formed, which leads to 33-fold enhanced light absorption for QWs centered at wavelength of 14.5 μm compared with isotropic absorption of QWs without any metallic microstructures, as well as a large value of coupling efficiency (η) of |Ez|2 ~ 6. This coupled mode shows a slight dispersion over ~40° and weak polarization dependence, which is quite beneficial to the high performance infrared photodetectors.

  16. High efficiency diffraction grating for EUV lithography beamline monochromator

    NASA Astrophysics Data System (ADS)

    Voronov, D. L.; Warwick, T.; Gullikson, E. M.; Salmassi, F.; Naulleau, P.; Artemiev, N. A.; Lum, P.; Padmore, H. A.

    2016-09-01

    A blazed diffraction grating for the EUV lithography Beamline 12.0.1 of the Advanced Light Source has been fabricated using optical direct write lithography and anisotropic wet etching technology. A variable line spacing pattern was recorded on a photoresist layer and transferred to a hard mask layer of the grating substrate by a plasma etch. Then anisotropic wet etching was applied to shape triangular grating grooves with precise control of the ultralow blaze angle. Variation of the groove density along the grating length was measured with a Long Trace Profiler (LTP). Fourier analysis of the LTP data confirmed high groove placement accuracy of the grating. The grating coated with a Ru coating demonstrated diffraction efficiency of 69.6% in the negative first diffraction order which is close to theoretical efficiency at the wavelength of 13.5 nm. This work demonstrates an alternative approach to fabrication of highly efficient and precise x-ray diffraction gratings with ultra-low blaze angles.

  17. High-efficiency Commercial Cold Climate Heat Pump

    SciTech Connect

    Mahmoud, Ahmad M.; Cogswell, F.; Verma, P.

    2015-08-28

    United Technologies Research Center (UTRC) proposed in 2012 to design, develop and demonstrate an air-source 10TR high-efficiency commercial cold climate heat pump (CCCHP). The proposed heat pump would be scalable beyond 40TR, cost effective with a simple payback of < 3 years upon commercialization and would reduce annual electricity use for building space heating in cold climates by at least 20%. This would represent an annual savings of $2.3 billion and a 20% displacement of total greenhouse gases generated upon full commercialization. The primary objective was to develop a highly integrated system that shall meet or exceed DOE capacity and efficiency targets at key conditions and is scalable, cost-effective and simple relative to the state-of-the-art. Specifically, the goal of the project was to design, develop and demonstrate a CCCHP that exceeds DOE capacity degradation requirements at +17F and -13F conditions (0 and <15% degradation vs. 10 and 25% DOE requirements, respectively) while meeting or exceeding DOE capacity and system efficiency requirements at all other conditions.

  18. A high efficiency hybrid stirling-pulse tube cryocooler

    NASA Astrophysics Data System (ADS)

    Wang, Xiaotao; Zhang, Yibing; Li, Haibing; Dai, Wei; Chen, Shuai; Lei, Gang; Luo, Ercang

    2015-03-01

    This article presented a hybrid cryocooler which combines the room temperature displacers and the pulse tube in one system. Compared with a traditional pulse tube cryocooler, the system uses the rod-less ambient displacer to recover the expansion work from the pulse tube cold end to improve the efficiency while still keeps the advantage of the pulse tube cryocooler with no moving parts at the cold region. In the meantime, dual-opposed configurations for both the compression pistons and displacers reduce the cooler vibration to a very low level. In the experiments, a lowest no-load temperature of 38.5 K has been obtained and the cooling power at 80K was 26.4 W with an input electric power of 290 W. This leads to an efficiency of 24.2% of Carnot, marginally higher than that of an ordinary pulse tube cryocooler. The hybrid configuration herein provides a very competitive option when a high efficiency, high-reliability and robust cryocooler is desired.

  19. Solution Chemistry Engineering toward High-Efficiency Perovskite Solar Cells.

    PubMed

    Zhao, Yixin; Zhu, Kai

    2014-12-04

    Organic and inorganic hybrid perovskites (e.g., CH3NH3PbI3) have emerged as a revolutionary class of light-absorbing semiconductors that has demonstrated a rapid increase in efficiency within a few years of active research. Controlling perovskite morphology and composition has been found critical to developing high-performance perovskite solar cells. The recent development of solution chemistry engineering has led to fabrication of greater than 15-17%-efficiency solar cells by multiple groups, with the highest certified 17.9% efficiency that has significantly surpassed the best-reported perovskite solar cell by vapor-phase growth. In this Perspective, we review recent progress on solution chemistry engineering processes and various control parameters that are critical to the success of solution growth of high-quality perovskite films. We discuss the importance of understanding the impact of solution-processing parameters and perovskite film architectures on the fundamental charge carrier dynamics in perovskite solar cells. The cost and stability issues of perovskite solar cells will also be discussed.

  20. Efficient temporal and interlayer parameter prediction for weighted prediction in scalable high efficiency video coding

    NASA Astrophysics Data System (ADS)

    Tsang, Sik-Ho; Chan, Yui-Lam; Siu, Wan-Chi

    2017-01-01

    Weighted prediction (WP) is an efficient video coding tool that was introduced since the establishment of the H.264/AVC video coding standard, for compensating the temporal illumination change in motion estimation and compensation. WP parameters, including a multiplicative weight and an additive offset for each reference frame, are required to be estimated and transmitted to the decoder by slice header. These parameters cause extra bits in the coded video bitstream. High efficiency video coding (HEVC) provides WP parameter prediction to reduce the overhead. Therefore, WP parameter prediction is crucial to research works or applications, which are related to WP. Prior art has been suggested to further improve the WP parameter prediction by implicit prediction of image characteristics and derivation of parameters. By exploiting both temporal and interlayer redundancies, we propose three WP parameter prediction algorithms, enhanced implicit WP parameter, enhanced direct WP parameter derivation, and interlayer WP parameter, to further improve the coding efficiency of HEVC. Results show that our proposed algorithms can achieve up to 5.83% and 5.23% bitrate reduction compared to the conventional scalable HEVC in the base layer for SNR scalability and 2× spatial scalability, respectively.

  1. AMTEC: High efficiency static conversion for space power

    NASA Technical Reports Server (NTRS)

    Bankston, C. P.; Shirbacheh, M.

    1986-01-01

    Future manned and unmanned space missions will require reliable, high efficiency energy conversion systems. For a manned Mars mission, power levels in the range of 10 to 100 kWe will be needed. The Alkali Metal Thermoelectric Converter (AMTEC) is a direct energy conversion technology with the potential to meet these needs. The AMTEC is a thermally regenerative electrochemical device that derives its operation from the sodium ion conducting properties of beta-alumina solid electrolyte (BASE). To date, an efficiency of 19%, area power density of 1 W/sq cm, and a lifetime of 10,000 hours at high temperature were demonstrated in laboratory devices. Systems studies show that projected AMTEC systems equal or surpass the performance of other static or dynamic systems in applications of 1 kWe-1 MWe. Thus, the laboratory experiments and applications studies conducted to date have shown that the AMTEC posseses great potential. In order to bring this technology to the stage where prototype units can be built and operated, several technical issues must be addressed. These include the need for long life, high power electrodes, minimization of radiative parasitic losses, and high temperature seals. In summary, the evidence shows that if AMTEC is developed, it can play a significant role in future space power applications.

  2. Tunable C2N Membrane for High Efficient Water Desalination

    PubMed Central

    Yang, Yanmei; Li, Weifeng; Zhou, Hongcai; Zhang, Xiaoming; Zhao, Mingwen

    2016-01-01

    Water scarcity represents one of the most serious global problems of our time and challenges the advancements in desalination techniques. Although water-filtering architectures based on graphene have greatly advanced the approach to high performance desalination membranes, the controlled-generation of nanopores with particular diameter is tricky and has stunted its wide applications. Here, through molecular dynamic simulations and first-principles calculations, we propose that the recently reported graphene-like carbon nitride (g-C2N) monolayer can serve as high efficient filters for water desalination. Taking the advantages of the intrisic nanoporous structure and excellent mechanical properties of g-C2N, high water transparency and strong salt filtering capability have been demonstrated in our simulations. More importantly, the “open” and “closed” states of the g-C2N filter can be precisely regulated by tensile strain. It is found that the water permeability of g-C2N is significantly higher than that reported for graphene filters by almost one order of magnitude. In the light of the abundant family of graphene-like carbon nitride monolayered materials, our results thus offer a promising approach to the design of high efficient filteration architectures. PMID:27384666

  3. Tunable C2N Membrane for High Efficient Water Desalination.

    PubMed

    Yang, Yanmei; Li, Weifeng; Zhou, Hongcai; Zhang, Xiaoming; Zhao, Mingwen

    2016-07-07

    Water scarcity represents one of the most serious global problems of our time and challenges the advancements in desalination techniques. Although water-filtering architectures based on graphene have greatly advanced the approach to high performance desalination membranes, the controlled-generation of nanopores with particular diameter is tricky and has stunted its wide applications. Here, through molecular dynamic simulations and first-principles calculations, we propose that the recently reported graphene-like carbon nitride (g-C2N) monolayer can serve as high efficient filters for water desalination. Taking the advantages of the intrisic nanoporous structure and excellent mechanical properties of g-C2N, high water transparency and strong salt filtering capability have been demonstrated in our simulations. More importantly, the "open" and "closed" states of the g-C2N filter can be precisely regulated by tensile strain. It is found that the water permeability of g-C2N is significantly higher than that reported for graphene filters by almost one order of magnitude. In the light of the abundant family of graphene-like carbon nitride monolayered materials, our results thus offer a promising approach to the design of high efficient filteration architectures.

  4. High efficiency copper ternary thin film solar cells

    SciTech Connect

    Basol, B.M.; Kapur, V.K. )

    1991-04-01

    This report describes work to develop a high efficiency, thin film CuInSe{sub 2} solar cell using a potentially low-cost process. The technique used in this development program is a two-stage process. The two-stage process involves depositing the metallic elements of the CuInSe{sub 2} compound (i.e., Cu and In) on a substrate in the form of stacked layers, and then selenizing this stacked metallic film in an atmosphere containing Se. Early results showed that the electrodeposition/selenization technique could yield CuInSe{sub 2} films with good electrical and optical properties on small-area substrates. This report concentrates on the later half of the research effort; this portion was directed toward developing a two-stage process using evaporated Cu-In layers. The selenization technique has the potential of yielding solar cells with efficiencies in excess of 15 percent. 7 refs., 12 figs.

  5. High efficiency rare-earth emitter for thermophotovoltaic applications

    SciTech Connect

    Sakr, E. S.; Zhou, Z.; Bermel, P.

    2014-09-15

    In this work, we propose a rare-earth-based ceramic thermal emitter design that can boost thermophotovoltaic (TPV) efficiencies significantly without cold-side filters at a temperature of 1573 K (1300 °C). The proposed emitter enhances a naturally occurring rare earth transition using quality-factor matching, with a quarter-wave stack as a highly reflective back mirror, while suppressing parasitic losses via exponential chirping of a multilayer reflector transmitting only at short wavelengths. This allows the emissivity to approach the blackbody limit for wavelengths overlapping with the absorption peak of the rare-earth material, while effectively reducing the losses associated with undesirable long-wavelength emission. We obtain TPV efficiencies of 34% using this layered design, which only requires modest index contrast, making it particularly amenable to fabrication via a wide variety of techniques, including sputtering, spin-coating, and plasma-enhanced chemical vapor deposition.

  6. High efficiency silicon nanohole/organic heterojunction hybrid solar cell

    NASA Astrophysics Data System (ADS)

    Hong, Lei; Wang, Xincai; Zheng, Hongyu; He, Lining; Wang, Hao; Yu, Hongyu; Rusli

    2014-02-01

    High efficiency hybrid solar cells are fabricated based on silicon with a nanohole (SiNH) structure and poly (3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS). The SiNH structure is fabricated using electroless chemical etching with silver catalyst, and the heterojunction is formed by spin coating of PEDOT on the SiNH. The hybrid cells are optimized by varying the hole depth, and a maximum power conversion efficiency of 8.3% is achieved with a hole depth of 1 μm. The SiNH hybrid solar cell exhibits a strong antireflection and light trapping property attributed to the sub-wavelength dimension of the SiNH structure.

  7. Design, fabrication and performance of high efficiency photovoltaic modules

    NASA Technical Reports Server (NTRS)

    Nowlan, M. J.; Kreisman, W. S.; Younger, P. R.

    1981-01-01

    Design details and performance and environmental test results of newly developed high performance and reliability photovoltaic modules are presented. Efficiencies averaging 14.3% for 3040 cells were obtained by using ion implantation for cell junction and back surface field formation. 152 rectangular (6.0 cm x 4.6 cm) cells arranged with a 97% local packing density comprise the circuit assembly, and cells are wired 4 in parallel by 38 in series. The top cover of the superstrate design module is composed of tempered low-iron glass to provide transparent protection for the optical surface. Results show that this design has an encapsulation system which does not fail in the event of reverse-bias operation, and an average module efficiency of 12.2% was achieved at a 58.6W power which varied only 2% among all 20 modules.

  8. High Efficient Universal Buck Boost Solar Array Regulator SAR Module

    NASA Astrophysics Data System (ADS)

    Kimmelmann, Stefan; Knorr, Wolfgang

    2014-08-01

    The high efficient universal Buck Boost Solar Array Regulator (SAR) module concept is applicable for a wide range of input and output voltages. The single point failure tolerant SAR module contains 3 power converters for the transfer of the SAR power to the battery dominated power bus. The converters are operating parallel in a 2 out of 3 redundancy and are driven by two different controllers. The output power of one module can be adjusted up to 1KW depending on the requirements. The maximum power point tracker (MPPT) is placed on a separate small printed circuit board and can be used if no external tracker signal is delivered. Depending on the mode and load conditions an efficiency of more than 97% is achievable. The stable control performance is achieved by implementing the magnetic current sense detection. The sensed power coil current is used in Buck and Boost control mode.

  9. High efficiency >26 W diode end-pumped Alexandrite laser.

    PubMed

    Teppitaksak, Achaya; Minassian, Ara; Thomas, Gabrielle M; Damzen, Michael J

    2014-06-30

    We show for the first time that multi-ten Watt operation of an Alexandrite laser can be achieved with direct red diode-pumping and with high efficiency. An investigation of diode end-pumped Alexandrite rod lasers demonstrates continuous-wave output power in excess of 26W, more than an order of magnitude higher than previous diode end-pumping systems, and slope efficiency 49%, the highest reported for a diode-pumped Alexandrite laser. Wavelength tuning from 730 to 792nm is demonstrated using self-seeding feedback from an external grating. Q-switched laser operation based on polarization-switching to a lower gain axis of Alexandrite has produced ~mJ-pulse energy at 1kHz pulse rate in fundamental TEM(00) mode.

  10. Highly efficient electroosmotic flow through functionalized carbon nanotube membranes

    NASA Astrophysics Data System (ADS)

    Wu, Ji; Gerstandt, Karen; Majumder, Mainak; Zhan, Xin; Hinds, Bruce J.

    2011-08-01

    Carbon nanotube membranes with inner diameter ranging from 1.5-7 nm were examined for enhanced electroosmotic flow. After functionalization via electrochemical diazonium grafting and carbodiimide coupling reaction, it was found that neutral caffeine molecules can be efficiently pumped via electroosmosis. An electroosmotic velocity as high as 0.16 cm s-1 V-1 has been observed. Power efficiencies were 25-110 fold improved compared to related nanoporous materials, which has important applications in chemical separations and compact medical devices. Nearly ideal electroosmotic flow was seen in the case where the mobile cation diameter nearly matched the inner diameter of the single-walled carbon nanotube resulting in a condition of using one ion is to pump one neutral molecule at equivalent concentrations.

  11. ECC ozonesonde performance at high altitudes: Pump efficiency

    NASA Technical Reports Server (NTRS)

    Torres, A. L.

    1981-01-01

    The ECC ozonesonde sampling behavior was examined at pressures ranging from 60 to 6 hPa with the objective of evaluating uncertainties in high altitude ozone data caused by variations in pumping efficiency. The averaged pump efficiency correction curve for a 43 sample set of 3A type ECC pumps showed a 2-3% bias from the curve provided by the manufacturer. In addition, random pump to pump variations (2 sigma) + or - were 5% at 6 hPa. These values probably represent minimum errors since the pumps were from the same production batch. A seven sample set of the newer 4A type ECC pumps was examined, with similar findings as for the 3A types.

  12. High efficiency silicon nanohole/organic heterojunction hybrid solar cell

    SciTech Connect

    Hong, Lei; Wang, Xincai; Zheng, Hongyu; He, Lining; Wang, Hao; Rusli E-mail: erusli@ntu.edu.sg; Yu, Hongyu E-mail: erusli@ntu.edu.sg

    2014-02-03

    High efficiency hybrid solar cells are fabricated based on silicon with a nanohole (SiNH) structure and poly (3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS). The SiNH structure is fabricated using electroless chemical etching with silver catalyst, and the heterojunction is formed by spin coating of PEDOT on the SiNH. The hybrid cells are optimized by varying the hole depth, and a maximum power conversion efficiency of 8.3% is achieved with a hole depth of 1 μm. The SiNH hybrid solar cell exhibits a strong antireflection and light trapping property attributed to the sub-wavelength dimension of the SiNH structure.

  13. Generation of High Efficiency Longitudinally Polarized Beam using High NA Lens Axicon and Dedicated Phase Filter

    SciTech Connect

    Rajesh, K. B.; Mohankumar, R.; Prathibajanet, C. Amala; Pillai, T. V. S.; Jaroszewicz, Z.

    2011-10-20

    We propose to use pure phase filter in combination with high NA lens axicon to achieve high efficient longitudinally polarized beam with a subwavelength spot size and large depth of focus using hyper geometric Gaussian beam. Using this system, the spot size is reduced to 0.392 {lambda} and the depth of focus is increased to 7 {lambda}. The efficiency of such system is found to be 87%. This high efficient longitudinally polarized beam generated by hyper geometric Gaussian beam is useful for most of the near-field optics applications.

  14. High-efficiency multilayer-dielectric diffraction gratings

    SciTech Connect

    Perry, M.D.; Boyd, R.D.; Britten, J.A.

    1996-06-01

    The ability to produce short laser pulses of extremely high power and high irradiance, as is needed for fast ignitor research in inertial confinement fusion, places increasing demands on optical components such as amplifiers, lenses, and mirrors that must remain undamaged by the radiation. The higher refractive index in the center of an intense laser beam acts as a focusing lens. The resulting wavefront distortion, left uncorrected, eventually leads to catastrophic filamentation. Major advances in energy extraction and resulting increases in focused irradiance have been made possible by the use of chirped-pulse amplification (CPA), long used in radar applications and newly applied to optical frequencies. Optical-frequency CPA systems begin with a mode-locked oscillator that produces low-energy seed pulses with durations of ten to a few hundred femtoseconds. As a result of the classical uncertainty relation between time and frequency, these short pulses have a very broad frequency distribution. A pair of diffraction gratings (or other dispersive elements) lengthens the laser pulse and induces a time-varying frequency (or chirp). Following amplification, diffraction gratings compress the pulse back to nearly the original duration. Typically a nanojoule, femtosecond pulse is stretched by a factor of several thousand and is amplified by as much as 12 orders of magnitude before recompression. By producing the short pulse only after amplification, this technique makes possible efficient extraction of energy from a variety of broadband solid state materials. Achieving high focused irradiance from a pulse ultimately requires both high peak power and excellent beam quality. There is therefore a demand for diffraction gratings that produce a high-quality diffracted wavefront, have high diffraction efficiency, and exhibit a high threshold for laser damage.

  15. High efficiency beam splitting for H/sup -/ accelerators

    SciTech Connect

    Kramer, S.L.; Stipp, V.; Krieger, C.; Madsen, J.

    1985-01-01

    Beam splitting for high energy accelerators has typically involved a significant loss of beam and radiation. This paper reports on a new method of splitting beams for H/sup -/ accelerators. This technique uses a high intensity flash of light to strip a fraction of the H/sup -/ beam to H/sup 0/ which are then easily separated by a small bending magnet. A system using a 900-watt (average electrical power) flashlamp and a highly efficient collector will provide 10/sup -3/ to 10/sup -2/ splitting of a 50 MeV H/sup -/ beam. Results on the operation and comparisons with stripping cross sections are presented. Also discussed is the possibility for developing this system to yield a higher stripping fraction.

  16. Highly efficient nanoplasmonic SERS on cardboard packaging substrates.

    PubMed

    Araújo, Andreia; Caro, Carlos; Mendes, Manuel J; Nunes, Daniela; Fortunato, Elvira; Franco, Ricardo; Águas, Hugo; Martins, Rodrigo

    2014-10-17

    This work reports on highly efficient surface enhanced Raman spectroscopy (SERS) constructed on low-cost, fully recyclable and highly reproducible cardboard plates, which are commonly used as disposable packaging material. The active optical component is based on plasmonic silver nanoparticle structures separated from the metal surface of the cardboard by a nanoscale dielectric gap. The SERS response of the silver (Ag) nanoparticles of various shapes and sizes were systematically investigated, and a Raman enhancement factor higher than 106 for rhodamine 6G detection was achieved. The spectral matching of the plasmonic resonance for maximum Raman enhancement with the optimal local electric field enhancement produced by 60 nm-sized Ag NPs predicted by the electromagnetic simulations reinforces the outstanding results achieved. Furthermore, the nanoplasmonic SERS substrate exhibited high reproducibility and stability. The SERS signals showed that the intensity variation was less than 5%, and the SERS performance could be maintained for up to at least 6 months.

  17. Photoconductive Cathode Interlayer for Highly Efficient Inverted Polymer Solar Cells.

    PubMed

    Nian, Li; Zhang, Wenqiang; Zhu, Na; Liu, Linlin; Xie, Zengqi; Wu, Hongbin; Würthner, Frank; Ma, Yuguang

    2015-06-10

    A highly photoconductive cathode interlayer was achieved by doping a 1 wt % light absorber, such as perylene bisimide, into a ZnO thin film, which absorbs a very small amount of light but shows highly increased conductivity of 4.50 × 10(-3) S/m under sunlight. Photovoltaic devices based on this kind of photoactive cathode interlayer exhibit significantly improved device performance, which is rather insensitive to the thickness of the cathode interlayer over a broad range. Moreover, a power conversion efficiency as high as 10.5% was obtained by incorporation of our photoconductive cathode interlayer with the PTB7-Th:PC71BM active layer, which is one of the best results for single-junction polymer solar cells.

  18. A Watermarking Scheme for High Efficiency Video Coding (HEVC)

    PubMed Central

    Swati, Salahuddin; Hayat, Khizar; Shahid, Zafar

    2014-01-01

    This paper presents a high payload watermarking scheme for High Efficiency Video Coding (HEVC). HEVC is an emerging video compression standard that provides better compression performance as compared to its predecessor, i.e. H.264/AVC. Considering that HEVC may will be used in a variety of applications in the future, the proposed algorithm has a high potential of utilization in applications involving broadcast and hiding of metadata. The watermark is embedded into the Quantized Transform Coefficients (QTCs) during the encoding process. Later, during the decoding process, the embedded message can be detected and extracted completely. The experimental results show that the proposed algorithm does not significantly affect the video quality, nor does it escalate the bitrate. PMID:25144455

  19. Fossil Fuel Biomarkers in Sewage Sludges: Environmental Significance

    NASA Astrophysics Data System (ADS)

    Payet, C.; Bryselbout, C.; Morel, J.-L.; Lichtfouse, E.

    Fossil fuel biomarkers, or "molecular fossils," are specific organic substances found in coals, petroleums, and sedimentary rocks. They are formed during millions of years of sedimentary burial by geochemical alteration of biological molecules, such as cholesterol, under the effect of biodegradation, temperature, pressure, and mineral catalysis, to produce geochemically mature molecules, for example, aromatic steroids (Fig. 1). Since fossil fuel biomarkers have a very specific molecular structure betraying fossil fuel sources, such markers should be useful in assessing the fossil fuel contamination of various modern media such as soils, plants, waters, and modern sediments. Here the identification of fossil fuel biomarkers of high geothermal maturity in sewage sludges provides evidence of the contamination of sludges by petroleum products. The most likely sources of contamination are contaminated vegetal food, road dust, and soil particles carried by rain water.

  20. 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

  1. A High Efficiency Grazing Incidence Pumped X-ray Laser

    SciTech Connect

    Dunn, J; Keenan, R; Price, D F; Patel, P K; Smith, R F; Shlyaptsev, V N

    2006-08-31

    The main objective of the project is to demonstrate a proof-of-principle, new type of high efficiency, short wavelength x-ray laser source that will operate at unprecedented high repetition rates (10Hz) that could be scaled to 1kHz or higher. The development of a high average power, tabletop x-ray laser would serve to complement the wavelength range of 3rd and future 4th generation light sources, e.g. the LCLS, being developed by DOE-Basic Energy Sciences. The latter are large, expensive, central, synchrotron-based facilities while the tabletop x-ray laser is compact, high-power laser-driven, and relatively inexpensive. The demonstration of such a unique, ultra-fast source would allow us to attract funding from DOE-BES, NSF and other agencies to pursue probing of diverse materials undergoing ultrafast changes. Secondly, this capability would have a profound impact on the semiconductor industry since a coherent x-ray laser source would be ideal for ''at wavelength'' {approx}13 nm metrology and microscopy of optics and masks used in EUV lithography. The project has major technical challenges. We will perform grazing-incidence pumped laser-plasma experiments in flat or groove targets which are required to improve the pumping efficiency by ten times. Plasma density characterization using our existing unique picosecond x-ray laser interferometry of laser-irradiated targets is necessary. Simulations of optical laser propagation as well as x-ray laser production and propagation through freely expanding and confined plasma geometries are essential. The research would be conducted using the Physics Directorate Callisto and COMET high power lasers. At the end of the project, we expect to have a high-efficiency x-ray laser scheme operating below 20 nm at 10Hz with a pulse duration of {approx}2 ps. This will represent the state-of-the-art in x-ray lasers and would be a major step forward from our present picosecond laser-driven x-ray lasers. There is an added bonus of creating

  2. The design of space optical communications terminal with high efficient

    NASA Astrophysics Data System (ADS)

    Deng, Xiaoguo; Li, Gang; Jiang, Bo; Yang, Xiaoxu; Yan, Peipei

    2015-02-01

    In order to improve high-speed laser space optical communications terminal receive energy and emission energy, meet the demand of mini-type and light-type for space-based bear platform, based on multiple-reflect coaxial optical receiving antenna structure, while considering the installation difficulty, a high-efficient optical system had been designed, which aperture is off-axial, both signal-receiving sub-optical system and emission sub-optical system share a same primary optical path. By the separating light lens behind the primary optical path, the received light with little energy will be filtered and shaped and then transmitted to each detector, at the same time, by the coupling element, the high-power laser will be coupling into optical antenna, and then emitted to outside. Applied the power-detected optical system evaluate principle, the optimized off-axial optical system's efficiency had been compared with the coaxial optical system. While, analyzed the Gauss beam energy distribution by numerical theory, discussed that whether off-axis optical system can be an emission terminal, verify the feasibility of the theory of the design of the system.

  3. High efficiency pulse tube cryocoolers for aerospace applications

    NASA Astrophysics Data System (ADS)

    Dang, Haizheng

    2014-01-01

    This paper reviews the recent advances in Stirling-type pulse tube cryocoolers for aerospace applications in the author's group. Due to the special environment featuring the limited power supply and adverse rejection condition, high cooler efficiencies are emphasized and thus the approaches to realize them are stressed. The cold fingers involve three geometries, and designs and optimizations on key dimensional parameters of coaxial and in-line ones for given compressors are discussed and compared. The high performance moving-coil linear compressors are studied, and the optimizations on linear motor and flexure springs are briefly reviewed as examples of studies on the key compressor technologies. The mature single-stage coolers cover 25-200 K with the capacities varying from milliwatt levels to over 30 W, and the high efficiencies at typical temperatures such as 40 K, 60 K, 80 K and 95 K are presented. The two-stage arrangement is becoming another trend to achieve cooling below 25 K and also to simultaneously provide cooling powers at both stages. Some typical development programs are introduced and a brief overview of the data package is updated.

  4. Biodesulfurization of fossil fuels.

    PubMed

    Gray, Kevin A; Mrachko, Gregory T; Squires, Charles H

    2003-06-01

    Biotechnological techniques enabling the specific removal of sulfur from fossil fuels have been developed. In the past three years there have been important advances in the elucidation of the mechanisms of biodesulfurization; some of the most significant relate to the role of a flavin reductase, DszD, in the enzymology of desulfurization, and to the use of new tools that enable enzyme enhancement via DNA manipulation to influence both the rate and the substrate range of Dsz. Also, a clearer understanding of the unique desulfinase step in the pathway has begun to emerge.

  5. High efficiency GaP power conversion for Betavoltaic applications

    NASA Technical Reports Server (NTRS)

    Sims, Paul E.; Dinetta, Louis C.; Barnett, Allen M.

    1994-01-01

    AstroPower is developing a gallium phosphide (GaP) based energy converter optimized for radio luminescent light-based power supplies. A 'two-step' or 'indirect' process is used where a phosphor is excited by radioactive decay products to produce light that is then converted to electricity by a photovoltaic energy converter. This indirect conversion of beta-radiation to electrical energy can be realized by applying recent developments in tritium based radio luminescent (RL) light sources in combination with the high conversion efficiencies that can be achieved under low illumination with low leakage, gallium phosphide based devices. This tritium to light approach is inherently safer than battery designs that incorporate high activity radionuclides because the beta particles emitted by tritium are of low average energy and are easily stopped by a thin layer of glass. GaP layers were grown by liquid phase epitaxy and p/n junction devices were fabricated and characterized for low light intensity power conversion. AstroPower has demonstrated the feasibility of the GaP based energy converter with the following key results: 23.54 percent conversion efficiency under 968 muW/sq cm 440 nm blue light, 14.59 percent conversion efficiency for 2.85 muW/sq cm 440 nm blue light, and fabrication of working 5 V array. We have also determined that at least 20 muW/sq cm optical power is available for betavoltaic power systems. Successful developments of this device is an enabling technology for low volume, safe, high voltage, milliwatt power supplies with service lifetimes in excess of 12 years.

  6. High efficiency GaP power conversion for Betavoltaic applications

    NASA Astrophysics Data System (ADS)

    Sims, Paul E.; Dinetta, Louis C.; Barnett, Allen M.

    1994-09-01

    AstroPower is developing a gallium phosphide (GaP) based energy converter optimized for radio luminescent light-based power supplies. A 'two-step' or 'indirect' process is used where a phosphor is excited by radioactive decay products to produce light that is then converted to electricity by a photovoltaic energy converter. This indirect conversion of beta-radiation to electrical energy can be realized by applying recent developments in tritium based radio luminescent (RL) light sources in combination with the high conversion efficiencies that can be achieved under low illumination with low leakage, gallium phosphide based devices. This tritium to light approach is inherently safer than battery designs that incorporate high activity radionuclides because the beta particles emitted by tritium are of low average energy and are easily stopped by a thin layer of glass. GaP layers were grown by liquid phase epitaxy and p/n junction devices were fabricated and characterized for low light intensity power conversion. AstroPower has demonstrated the feasibility of the GaP based energy converter with the following key results: 23.54 percent conversion efficiency under 968 muW/sq cm 440 nm blue light, 14.59 percent conversion efficiency for 2.85 muW/sq cm 440 nm blue light, and fabrication of working 5 V array. We have also determined that at least 20 muW/sq cm optical power is available for betavoltaic power systems. Successful developments of this device is an enabling technology for low volume, safe, high voltage, milliwatt power supplies with service lifetimes in excess of 12 years.

  7. A Highly Efficient and Facile Approach for Fabricating Graphite Nanoplatelets

    NASA Astrophysics Data System (ADS)

    Van Thanh, Dang; Van Thien, Nguyen; Thang, Bui Hung; Van Chuc, Nguyen; Hong, Nguyen Manh; Trang, Bui Thi; Lam, Tran Dai; Huyen, Dang Thi Thu; Hong, Phan Ngoc; Minh, Phan Ngoc

    2016-05-01

    In this study, we report a highly efficient, convenient, and cost-effective technique for producing graphite nanoplatelets (GNPs) from plasma-expanded graphite oxides (PEGOs) obtained directly from low-cost, recycled graphite electrodes of used batteries, x-ray diffraction, Raman spectroscopy, and x-ray photoelectron spectroscopy confirmed the successful preparation of GNPs. Scanning electron microscopy revealed that the GNPs have lateral width from several hundreds of nanometers to 1.5 μm with an approximate thickness of 20-50 nm. These GNPs can serve as a precursor for the preparation of GNPs-based nanocomposite.

  8. Superlattices and multilayer structures for high efficiency solar cells

    NASA Technical Reports Server (NTRS)

    Wagner, M.; Leburton, J. P.

    1985-01-01

    Possible applications of superlattices to photovoltaic structures are discussed. A new concept based on doping superstructures (NIPI) can be exploited to significantly reduce recombination losses in III-V compound solar cells. A novel multijunction structure with lateral current transport is proposed. A computer simulation has been performed which shows that by optimizing the multilayer structure, short circuit current is substantially increased with minimum drop in open circuit voltage. An additional advantage of the structure is enhanced radiation tolerance. It is anticipated that this multilayer structure can be incorporated in multibandgap cells to achieve high efficiencies.

  9. Plasmonic energy nanofocusing for high-efficiency laser fusion ignition

    NASA Astrophysics Data System (ADS)

    Tanabe, Katsuaki

    2016-08-01

    We propose an efficient laser fusion ignition system consisting of metal nanoparticles or nanoshells embedded in conventional deuterated polystyrene fuel targets. The incident optical energy of the heating laser is highly concentrated around the metallic particulates randomly dispersed inside imploded targets due to the electromagnetic-field-enhancement effect by surface plasmon resonance, and thus effectively triggers nuclear-fusion chain reactions. Our preliminary calculations exhibit field enhancement factors of around 50 and 1100 for spherical Ag nanoparticles and Ag/SiO2 nanoshells, respectively, in the 1-µm band.

  10. Cascade: a high-efficiency ICF power reactor

    SciTech Connect

    Pitts, J.H.

    1985-10-31

    Cascade attains a net power-plant efficiency of 49% and its cost is competitive with high-temperature gas-cooled reactor, pressurized-water reactor, and coal-fired power plants. The Cascade reactor and blanket are made of ceramic materials and activation is 6 times less than that of the MARS Tandem Mirror Reactor operating at comparable power. Hands-on maintenance of the heat exchangers is possible one day after shutdown. Essentially all tritium is recovered in the vacuum system, with the remainder recovered from the helium power conversion loop. Tritium leakage external to the vacuum system and power conversion loop is only 0.03 Ci/d.

  11. Computing highly specific and mismatch tolerant oligomers efficiently.

    PubMed

    Yamada, Tomoyuki; Morishita, Shinichi

    2003-01-01

    The sequencing of the genomes of a variety of species and the growing databases containing expressed sequence tags (ESTs) and complementary DNAs (cDNAs) facilitate the design of highly specific oligomers for use as genomic markers, PCR primers, or DNA oligo microarrays. The first step in evaluating the specificity of short oligomers of about twenty units in length is to determine the frequencies at which the oligomers occur. However, for oligomers longer than about fifty units this is not efficient, as they usually have a frequency of only 1. A more suitable procedure is to consider the mismatch tolerance of an oligomer, that is, the minimum number of mismatches that allows a given oligomer to match a sub-sequence other than the target sequence anywhere in the genome or the EST database. However, calculating the exact value of mismatch tolerance is computationally costly and impractical. Therefore, we studied the problem of checking whether an oligomer meets the constraint that its mismatch tolerance is no less than a given threshold. Here, we present an efficient dynamic programming algorithm solution that utilizes suffix and height arrays. We demonstrated the effectiveness of this algorithm by efficiently computing a dense list of oligo-markers applicable to the human genome. Experimental results show that the algorithm runs faster than well-known Abrahamson's algorithm by orders of magnitude and is able to enumerate 63% to approximately 79% of qualified oligomers.

  12. Computing highly specific and noise-tolerant oligomers efficiently.

    PubMed

    Yamada, Tomoyuki; Morishita, Shinichi

    2004-03-01

    The sequencing of the genomes of a variety of species and the growing databases containing expressed sequence tags (ESTs) and complementary DNAs (cDNAs) facilitate the design of highly specific oligomers for use as genomic markers, PCR primers, or DNA oligo microarrays. The first step in evaluating the specificity of short oligomers of about 20 units in length is to determine the frequencies at which the oligomers occur. However, for oligomers longer than about fifty units this is not efficient, as they usually have a frequency of only 1. A more suitable procedure is to consider the mismatch tolerance of an oligomer, that is, the minimum number of mismatches that allows a given oligomer to match a substring other than the target sequence anywhere in the genome or the EST database. However, calculating the exact value of mismatch tolerance is computationally costly and impractical. Therefore, we studied the problem of checking whether an oligomer meets the constraint that its mismatch tolerance is no less than a given threshold. Here, we present an efficient dynamic programming algorithm solution that utilizes suffix and height arrays. We demonstrated the effectiveness of this algorithm by efficiently computing a dense list of numerous oligo-markers applicable to the human genome. Experimental results show that the algorithm runs faster than well-known Abrahamson's algorithm by orders of magnitude and is able to enumerate 65% approximately 76% of qualified oligomers.

  13. Commissioning of the High Efficiency Total Absorption Spectrometer (HECTOR)

    NASA Astrophysics Data System (ADS)

    Reingold, C. S.; Simon, A.; Spyrou, A.; Naqvi, F.; Dombos, A.; Palmisano, A.; Anderson, T.; Henderson, S. L.; Moylan, S.; Seymour, C.; Skulski, M. A.; Smith, M. K.; Strauss, S. Y.; Vande Kolk, B.

    2016-09-01

    P-process nucleosynthesis occurs in supernovae where the s-process seeds are present, and is responsible for the production of proton-rich nuclei. Photons from SN explosions induce characteristic (γ,n), (γ,p), and (γ , α) reactions. These reactions are typically studied via the inverse reactions. For this purpose, the High Efficiency Total Absorption Spectrometer (HECTOR), a NaI(Tl) summing detector at the University of Notre Dame, was built. The array is designed to make precision cross section measurements for (p, γ) and (α , γ) reactions. HECTOR is composed of 16 separate NaI(Tl) crystals and 32 photomultiplier tubes read by a digital data acquisition system, with gain-matching and summing done offline. The efficiency of HECTOR is about 52.7 (2.0)% for a 60Co source. The commissioning run for HECTOR was performed via measurements of known resonances in the 27Al(p, γ)28Si reaction to determine the efficiency of the array. The first results from HECTOR will be presented, as well as future plans with the array. This work was supported by the National Science Foundation under Grants No. PHY1614442 and PHY1430152 (JINA-CEE).

  14. Highly efficient entanglement swapping and teleportation at telecom wavelength.

    PubMed

    Jin, Rui-Bo; Takeoka, Masahiro; Takagi, Utako; Shimizu, Ryosuke; Sasaki, Masahide

    2015-03-20

    Entanglement swapping at telecom wavelengths is at the heart of quantum networking in optical fiber infrastructures. Although entanglement swapping has been demonstrated experimentally so far using various types of entangled photon sources both in near-infrared and telecom wavelength regions, the rate of swapping operation has been too low to be applied to practical quantum protocols, due to limited efficiency of entangled photon sources and photon detectors. Here we demonstrate drastic improvement of the efficiency at telecom wavelength by using two ultra-bright entangled photon sources and four highly efficient superconducting nanowire single photon detectors. We have attained a four-fold coincidence count rate of 108 counts per second, which is three orders higher than the previous experiments at telecom wavelengths. A raw (net) visibility in a Hong-Ou-Mandel interference between the two independent entangled sources was 73.3 ± 1.0% (85.1 ± 0.8%). We performed the teleportation and entanglement swapping, and obtained a fidelity of 76.3% in the swapping test. Our results on the coincidence count rates are comparable with the ones ever recorded in teleportation/swapping and multi-photon entanglement generation experiments at around 800 nm wavelengths. Our setup opens the way to practical implementation of device-independent quantum key distribution and its distance extension by the entanglement swapping as well as multi-photon entangled state generation in telecom band infrastructures with both space and fiber links.

  15. Features of photoconversion in highly efficient silicon solar cells

    SciTech Connect

    Sachenko, A. V.; Shkrebtii, A. I.; Korkishko, R. M.; Kostylyov, V. P.; Kulish, N. R.; Sokolovskyi, I. O.

    2015-02-15

    The photoconversion efficiency η in highly efficient silicon-based solar cells (SCs) is analyzed depending on the total surface-recombination rate S{sub s} on illuminated and rear surfaces. Solar cells based on silicon p-n junctions and α-Si:H or α-SiC:H-Si heterojunctions (so-called HIT structures) are considered in a unified approach. It is shown that a common feature of these SCs is an increased open-circuit voltage V{sub oc} associated with an additional contribution of the rear surface. Within an approach based on analysis of the physical features of photoconversion in SCs, taking into account the main recombination mechanisms, including Shockley-Read-Hall recombination, radiative recombination, surface recombination, recombination in the space-charge region, and band-to-band Auger recombination, expressions for the photoconversion efficiency of such SCs are obtained. The developed theory is compared with experiments, including those for SCs with record parameters, e.g., η = 25% and 24.7% for SCs with a p-n junction for HIT structures, respectively, under AM1.5 conditions. By comparing theory and experiment, the values of S{sub s} achieved as a result of recombination-loss minimization by various methods are determined. The results of calculations of the maximum possible value η{sub max} in silicon SCs are compared with the data of other papers. Good agreement is observed.

  16. A High Efficiency PSOFC/ATS-Gas Turbine Power System

    SciTech Connect

    W.L. Lundberg; G.A. Israelson; M.D. Moeckel; S.E. Veyo; R.A. Holmes; P.R. Zafred; J.E. King; R.E. Kothmann

    2001-02-01

    A study is described in which the conceptual design of a hybrid power system integrating a pressurized Siemens Westinghouse solid oxide fuel cell generator and the Mercury{trademark} 50 gas turbine was developed. The Mercury{trademark} 50 was designed by Solar Turbines as part of the US. Department of Energy Advanced Turbine Systems program. The focus of the study was to develop the hybrid power system concept that principally would exhibit an attractively-low cost of electricity (COE). The inherently-high efficiency of the hybrid cycle contributes directly to achieving this objective, and by employing the efficient, power-intensive Mercury{trademark} 50, with its relatively-low installed cost, the higher-cost SOFC generator can be optimally sized such that the minimum-COE objective is achieved. The system cycle is described, major system components are specified, the system installed cost and COE are estimated, and the physical arrangement of the major system components is discussed. Estimates of system power output, efficiency, and emissions at the system design point are also presented. In addition, two bottoming cycle options are described, and estimates of their effects on overall-system performance, cost, and COE are provided.

  17. Predicting high harmonic ion cyclotron heating efficiency in Tokamak plasmas

    SciTech Connect

    Green, David L; Jaeger, E. F.; Berry, Lee A; Chen, Guangye; Ryan, Philip Michael; Canik, John

    2011-01-01

    Observations of improved radio frequency (RF) heating efficiency in high-confinement (H-) mode plasmas on the National Spherical Tokamak Experiment (NSTX) are investigated by whole-device linear simulation. We present the first full-wave simulation to couple kinetic physics of the well confined core plasma to the poorly confined scrape-off plasma. The new simulation is used to scan the launched fast-wave spectrum and examine the steady-state electric wave field structure for experimental scenarios corresponding to both reduced, and improved RF heating efficiency. We find that launching toroidal wave-numbers that required for fast-wave propagation excites large amplitude (kVm 1 ) coaxial standing modes in the wave electric field between the confined plasma density pedestal and conducting vessel wall. Qualitative comparison with measurements of the stored plasma energy suggest these modes are a probable cause of degraded heating efficiency. Also, the H-mode density pedestal and fast-wave cutoff within the confined plasma allow for the excitation of whispering gallery type eigenmodes localised to the plasma edge.

  18. 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.

  19. High-efficiency shock-wave generator for extracorporeal lithotripsy.

    PubMed

    Broyer, P; Cathignol, D; Theillère, Y; Mestas, J L

    1996-09-01

    In extracorporeal lithotripsy, the electro-acoustic efficiency of electrohydraulic generators is limited by the inductance of the electrical discharge circuit. A new shock-wave generator is described that uses a coaxial discharge line enabling electro-acoustic efficiency to be greatly increased. The line is built using a para-electric ceramic with a relative dielectric constant of 1700, manufactured for use in high-voltage impulse mode. A coaxial spark gap, with minimal inductance, has been developed to obtain the triggered breakdown of the discharge line. Shock waves are created with a coaxial electrode plugged directly into the spark gap and immersed in an electrolyte of degassed saline. Electrode gap and electrolyte resistivity are adjusted to match the resistivity of the electrolyte volume between the underwater electrodes to the characteristic impedance of the line. The discharge line generates in the medium a rectangular current pulse with an amplitude of about 6000 A and a rise time of 50 ns. Compared with conventional generators, measurements of the expansive peak pressure pulse show an increase of 105% at 10 kV, 86.5% at 12 kV and 34.5% at 14 kV charging voltage. Electro-acoustic efficiency is found to be 11% instead of 5.5% for a conventional discharge circuit.

  20. High-efficiency integrated piezoelectric energy harvesting systems

    NASA Astrophysics Data System (ADS)

    Hande, Abhiman; Shah, Pradeep

    2010-04-01

    This paper describes hierarchically architectured development of an energy harvesting (EH) system that consists of micro and/or macro-scale harvesters matched to multiple components of remote wireless sensor and communication nodes. The micro-scale harvesters consist of thin-film MEMS piezoelectric cantilever arrays and power generation modules in IC-like form to allow efficient EH from vibrations. The design uses new high conversion efficiency thin-film processes combined with novel cantilever structures tuned to multiple resonant frequencies as broadband arrays. The macro-scale harvesters are used to power the collector nodes that have higher power specifications. These bulk harvesters can be integrated with efficient adaptive power management circuits that match transducer impedance and maximize power harvested from multiple scavenging sources with very low intrinsic power consumption. Texas MicroPower, Inc. is developing process based on a composition that has the highest reported energy density as compared to other commercially available bulk PZT-based sensor/actuator ceramic materials and extending it to thin-film materials and miniature conversion transducer structures. The multiform factor harvesters can be deployed for several military and commercial applications such as underground unattended sensors, sensors in oil rigs, structural health monitoring, supply chain management, and battlefield applications such as sensors on soldier apparel, equipment, and wearable electronics.