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Sample records for achieve highly efficient

  1. 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.

  2. Tuning charge balance in PHOLEDs with ambipolar host materials to achieve high efficiency

    SciTech Connect

    Padmaperuma, Asanga B.; Koech, Phillip K.; Cosimbescu, Lelia; Polikarpov, Evgueni; Swensen, James S.; Chopra, Neetu; So, Franky; Sapochak, Linda S.; Gaspar, Daniel J.

    2009-08-27

    The efficiency and stability of blue organic light emitting devices (OLEDs) continue to be a primary roadblock to developing organic solid state white lighting. For OLEDs to meet the high power conversion efficiency goal, they will require both close to 100% internal quantum efficiency and low operating voltage in a white light emitting device.1 It is generally accepted that such high quantum efficiency, can only be achieved with the use of organometallic phosphor doped OLEDs. Blue OLEDs are particularly important for solid state lighting. The simplest (and therefore likely the lowest cost) method of generating white light is to down convert part of the emission from a blue light source with a system of external phosphors.2 A second method of generating white light requires the superposition of the light from red, green and blue OLEDs in the correct ratio. Either of these two methods (and indeed any method of generating white light with a high color rendering index) critically depends on a high efficiency blue light component.3 A simple OLED generally consists of a hole-injecting anode, a preferentially hole transporting organic layer (HTL), an emissive layer that contains the recombination zone and ideally transports both holes and electrons, a preferentially electron-transporting layer (ETL) and an electron-injecting cathode. Color in state-of-the-art OLEDs is generated by an organometallic phosphor incorporated by co-sublimation into the emissive layer (EML).4 New materials functioning as hosts, emitters, charge transporting, and charge blocking layers have been developed along with device architectures leading to electrophosphorescent based OLEDs with high quantum efficiencies near the theoretical limit. However, the layers added to the device architecture to enable high quantum efficiencies lead to higher operating voltages and correspondingly lower power efficiencies. Achievement of target luminance power efficiencies will require new strategies for lowering

  3. Subpixel shift with Fourier transform to achieve efficient and high-quality image interpolation

    NASA Astrophysics Data System (ADS)

    Chen, Qin-Sheng; Weinhous, Martin S.

    1999-05-01

    A new approach to image interpolation is proposed. Different from the conventional scheme, the interpolation of a digital image is achieved with a sub-unity coordinate shift technique. In the approach, the original image is first shifted by sub-unity distances matching the locations where the image values need to be restored. The original and the shifted images are then interspersed together, yielding an interpolated image. High quality sub-unity image shift which is crucial to the approach is accomplished by implementing the shift theorem of Fourier transformation. It is well known that under the Nyquist sampling criterion, the most accurate image interpolation can be achieved with the interpolating function (sinc function). A major drawback is its computation efficiency. The present approach can achieve an interpolation quality as good as that with the sinc function since the sub-unity shift in Fourier domain is equivalent to shifting the sinc function in spatial domain, while the efficiency, thanks to the fast Fourier transform, is very much improved. In comparison to the conventional interpolation techniques such as linear or cubic B-spline interpolation, the interpolation accuracy is significantly enhanced. In order to compensate for the under-sampling effects in the interpolation of 3D medical images owing to a larger inter-slice distance, proper window functions were recommended. The application of the approach to 2- and 3-D CT and MRI images produced satisfactory interpolation results.

  4. Progress toward achieving high power and high efficiency semipolar LEDs and their characterization

    NASA Astrophysics Data System (ADS)

    Zhong, Hong

    Performance of current commercially available wurtzite nitride based light-emitting diodes (LEDs), grown along the polar (0001) c-plane orientation, is limited by the presence of polarization-related electric fields inside multi-quantum wells (MQWs). The discontinuities in both spontaneous and piezoelectric polarization at the heterointerfaces result in internal electric fields in the quantum wells. These electric fields cause carrier separation [quantum confined Stark effect (QCSE)] and reduce the radiative recombination rate within the quantum wells. One approach to reduce and possibly eliminate the polarization-related effects is to grow III-nitride devices on crystal planes that are inclined with respect to the c-axis, i.e., on semipolar planes. In this dissertation, metalorganic chemical vapor deposition (MOCVD) has been employed for the homoepitaxial growth of GaN based LEDs on semipolar orientations. As a consequence of growing on high-quality bulk GaN substrates, the LEDs have significantly reduced threading dislocation and stacking fault densities, resulting in remarkable improvements in EQE and output power. High efficiency semipolar (1011) violet-blue and blue LEDs have been demonstrated without any intentional effort to enhance the light extraction from those devices. Optimizations of epitaxial structures have led to increased output power and external quantum efficiency. A silicone encapsulated single quantum well blue LED with peak wavelength of 444 nm with output power of 24.3 mW, external quantum efficiency of 43% and luminous efficacy of 75 lm/W (with phosphorescent coating) at 20 mA has been demonstrated. Polarization fields in strained (1011) and (112¯2) InGaN quantum wells have been experimentally determined through bias-dependent optical studies. Our results show that the polarization field flips its direction in semipolar InGaN quantum wells with large inclination angles (i.e. around 60°). This suggests that there exists a polarization

  5. Polyaspartamide derivative nanoparticles with tunable surface charge achieve highly efficient cellular uptake and low cytotoxicity.

    PubMed

    Xu, Min; Zhao, Yuefang; Feng, Min

    2012-08-07

    Cationic nanocarrier mediated intracellular therapeutic agent delivery acts as a double-edged sword: the carriers promote cellular uptake, but interact nonspecifically and strongly with negatively charged endogenic proteins and cell membranes, which results in aggregates and high cytotoxicity. The present study was aimed at exploring zwitterionic polyaspartamide derivative nanoparticles for efficient intracellular delivery with low cytotoxicity. Poly(aspartic acid) partially grafted tetraethylenepentamine (PASP-pg-TEPA) with different isoelectric points (IEPs) was synthesized. The PASP-pg-TEPA formed zwitterionic nanoparticles with an irregular core and a well-defined shell structure in aqueous medium. Their particle size decreased from about 300 to 80 nm with an increase of the IEP from 7.5 to 9.1. The surface charge of the PASP-pg-TEPA nanoparticles could be tuned from positive to negative with a change of the pH of the medium. The nanoparticles with an IEP above 8.5 exhibited good stability under simulated physiological conditions. It was noted that the zwitterionic PASP-pg-TEPA nanoparticles displayed highly efficient cellular uptake in HeLa cells (approximately 99%) in serum-containing medium and did not adversely affect the cell viability at concentrations up to 1 mg/mL. Furthermore, thermodynamic analysis using isothermal titration calorimetry provided direct evidence that these zwitterionic nanoparticles had low binding affinities for serum protein. Therefore, the zwitterionic PASP-pg-TEPA nanoparticles could overcome limitations of cationic nanocarriers and achieve efficient intracellular delivery with low cytotoxicity.

  6. Achieving high efficiency laminated polymer solar cell with interfacial modified metallic electrode and pressure induced crystallization

    NASA Astrophysics Data System (ADS)

    Yuan, Yongbo; Bi, Yu; Huang, Jinsong

    2011-02-01

    We report efficient laminated organic photovoltaic device with efficiency approach the optimized device by regular method based on Poly(3-hexylthiophene-2,5-diyl) and [6,6]-phenyl-C61-butyric acid methyl ester (PCBM). The high efficiency is mainly attributed to the formation of a concrete polymer/metal interface mechanically and electrically by the use of electronic-glue, and using the highly conductive and flexible silver film as anode to reduce photovoltage loss and modifying its work function for efficiency hole extraction by ultraviolet/ozone treatment, and the pressure induced crystallization of PCBM.

  7. Swine herds achieve high performance by culling low lifetime efficiency sows in early parity.

    PubMed

    Takanashi, Ariko; McTaggart, Iain; Koketsu, Yuzo

    2011-11-01

    Sow lifetime performance and by-parity performance were analyzed using a 3 by 3 factorial design, comprising 3 herd productivity groups and 3 sow efficiency groups. Data was obtained from 101 Japanese herds, totaling 173,526 parity records of 34,929 sows, for the years 2001 to 2006. Sows were categorized into 3 groups based on the lower and upper 25th percentiles of the annualized lifetime pigs born alive: low lifetime efficiency sows (LE sows), intermediate lifetime efficiency sows or high lifetime efficiency sows. Herds were grouped on the basis of the upper and lower 25th percentiles of pigs weaned per mated female per year, averaged over 6 years: high-, intermediate- or low-performing herds. Mixed-effects models were used for comparisons. LE sows in high-performing herds had 57.8 fewer lifetime nonproductive days and 0.5 earlier parity at removal than those in low-performing herds (P<0.05). The number of pigs born alive of LE sows continuously decreased from parity 1 to 5, whereas those of high lifetime efficiency sows gradually increased from parity 1 to 4 before decreasing up to parity ≥ 6 (P<0.05). In conclusion, the LE sows have a performance pattern of decreasing number of pigs born alive across parity. The present study also indicates that high-performing herds culled potential LE sows earlier than the other herds.

  8. A Strategy to Achieve High-Efficiency Organolead Trihalide Perovskite Solar Cells

    NASA Astrophysics Data System (ADS)

    Andalibi, Shabnam; Rostami, Ali; Darvish, Ghafar; Moravvej-Farshi, Mohammad Kazem

    2016-11-01

    Recent theoretical and experimental reports have shown that organometal lead halide perovskite solar cells have attracted attention as a low-cost photovoltaic technology offering high power conversion efficiency. However, the photovoltaic efficiency of these materials is still limited by poor chemical and structural stability in the case of methylammonium lead triiodide and by large bandgap in the case of methylammonium lead tribromide or trichloride. To obtain high-performance devices, we have investigated the computationally optimal efficiency for these materials using the detailed-balance method and present optimal intermediate-band perovskite solar cells with high open-circuit voltage. We model different halide perovskites using density function theory calculations and study their bandgap and absorption coefficient. Based on calculation results, surprisingly Hg doping in different halide perovskites introduces a narrow partially filled intermediate band in the forbidden bandgap. We investigate electrical and optical properties of MAPb0.97Hg0.03I3, MAPb0.96Hg0.04Br3, and MAPb0.96Hg0.04Cl3 and calculate the high absorption efficiency of the different perovskite structures to create thin films suitable for photovoltaic devices.

  9. Achieving Efficiencies in Army Installations.

    DTIC Science & Technology

    2007-11-02

    34" ’■■"■" 1 USAWC STRATEGY RESEARCH PROJECT Achieving Efficiencies in Army Installations by Richard Fliss Col. Richard M. Meinhart Project...government agency. STRATEGY RESEARCH PROJECT ACHIEVING EFFICIENCIES IN ARMY INSTALLATIONS BY RICHARD FLISS DISTRIBUTION STATEMENT A: Approved...for public release. Distribution is unlimited. DTIC QUALITY INSPECTED & USAWC CLASS OF 1998 U.S. ARMY WAR COLLEGE, CARLISLE BARRACKS, PA 17013-5050

  10. Expert Meeting Report: Achieving the Best Installed Performance from High-Efficiency Residential Gas Furnaces

    SciTech Connect

    Brand, Larry

    2012-03-01

    This report describes a Building America expert meeting hosted on July 28, 2011, by the Partnership for Advanced Residential Retrofit (PARR) team. The purpose of this meeting was to identify installation practices that provide the best installed efficiency for residential gas furnaces, explain how AFUE and field efficiency can differ, and investigate the impact of installation practices on the efficiency and long-term durability of the furnace.

  11. Expert Meeting Report: Achieving the Best Installed Performance from High-Efficiency Residential Gas Furnaces

    SciTech Connect

    Brand, L.

    2012-03-01

    This report describes a Building America expert meeting hosted on July 28, 2011, by the Partnership for Advanced Residential Retrofit team. The purpose of this meeting was to identify installation practices that provide the best installed efficiency for residential gas furnaces, explain how AFUE and field efficiency can differ, and investigate the impact of installation practices on the efficiency and long-term durability of the furnace.

  12. High-Efficiency Rooftop Air Conditioners: Innovative Procurement to Achieve Advances in Technology

    SciTech Connect

    Hollomon, Brad

    2003-08-01

    The U.S. Department of Energy, Defense Logistics Agency, and Pacific Northwest National Laboratory recently conducted a technology procurement to increase the availability of energy-efficient, packaged unitary ''rooftop'' air conditioners. The procurement encouraged air conditioner manufacturers to produce equipment that exceeded US energy efficiency standards by at least 25% at a lower life-cycle cost. An outgrowth of the project, a web-based cost estimator tool is now available to help consumers determine the cost-effectiveness of purchasing energy-efficient air conditioners based on climate conditions and other factors at their own locations.

  13. Procuring High-Efficiency Air Conditioners: Harnessing Competition to Achieve Advances in Technology

    SciTech Connect

    Hollomon, J Bradford; Gordon, Kelly L.

    2002-03-01

    The Departments of Energy and Defense have joined forces to devise an innovative approach to acquiring more efficient unitary air conditioners that minimize life-cycle cost through improved technology. The resulting procurement solicitation challenges manufacturers to offer products with reduced life-cycle cost, taking into account both the initial prices of their units and the costs of their ongoing electric consumption. Competing products are evaluated according to a formula that reflects both full- and part-load efficiencies under a simulated set of time-varying climate conditions. The authors will report on the progress of the procurement, including the choice of target product based on market prospects and technology readiness, development of the technical specifications and electric consumption simulator, approaches to administrative and procedural challenges, responses from manufacturers, and plans for product promotion in the future.

  14. The hybrid progress note: semiautomating daily progress notes to achieve high-quality documentation and improve provider efficiency.

    PubMed

    Kargul, George J; Wright, Scott M; Knight, Amy M; McNichol, Mary T; Riggio, Jeffrey M

    2013-01-01

    Health care institutions are moving toward fully functional electronic medical records (EMRs) that promise improved documentation, safety, and quality of care. However, many hospitals do not yet use electronic documentation. Paper charting, including writing daily progress notes, is time-consuming and error prone. To improve the quality of documentation at their hospital, the authors introduced a highly formatted paper note template (hybrid note) that is prepopulated with data from the EMR. Inclusion of vital signs and active medications improved from 75.5% and 60% to 100% (P < .001), respectively. The use of unapproved abbreviations in the medication list decreased from 13.3% to 0% (P < .001). Prepopulating data enhances provider efficiency. Interviews of key clinician leaders also suggest that the initiative is well accepted and that documentation quality is enhanced. The hybrid progress note improves documentation and provider efficiency, promotes quality care, and initiates the development of the forthcoming electronic progress note.

  15. Experimental investigation of precision grinding oriented to achieve high process efficiency for large and middle-scale optic

    NASA Astrophysics Data System (ADS)

    Li, Ping; Jin, Tan; Guo, Zongfu; Lu, Ange; Qu, Meina

    2016-10-01

    High efficiency machining of large precision optical surfaces is a challenging task for researchers and engineers worldwide. The higher form accuracy and lower subsurface damage helps to significantly reduce the cycle time for the following polishing process, save the cost of production, and provide a strong enabling technology to support the large telescope and laser energy fusion projects. In this paper, employing an Infeed Grinding (IG) mode with a rotary table and a cup wheel, a multi stage grinding process chain, as well as precision compensation technology, a Φ300mm diameter plano mirror is ground by the Schneider Surfacing Center SCG 600 that delivers a new level of quality and accuracy when grinding such large flats. Results show a PV form error of Pt<2 μm, the surface roughness Ra<30 nm and Rz<180 nm, with subsurface damage <20 μm, and a material removal rates of up to 383.2 mm3/s.

  16. Side-Chain Fluorination: An Effective Approach to Achieving High-Performance All-Polymer Solar Cells with Efficiency Exceeding 7.

    PubMed

    Oh, Jiho; Kranthiraja, Kakaraparthi; Lee, Changyeon; Gunasekar, Kumarasamy; Kim, Seonha; Ma, Biwu; Kim, Bumjoon J; Jin, Sung-Ho

    2016-12-01

    Side-chain fluorination of polymers is demonstrated as a highly effective strategy to improve the efficiency of all-polymer solar cells from 2.93% (nonfluorinated P1) to 7.13% (fluorinated P2). This significant enhancement is achieved by synergistic improvements in open-circuit voltage, charge generation, and charge transport, as fluorination of the donor polymer optimizes the band alignment and the film morphology.

  17. 1010 Amplification and phase conjugation with high efficiency achieved by overcoming noise limitations in Brillouin two-beam coupling

    NASA Astrophysics Data System (ADS)

    Glick, Yaakov; Sternklar, Shmuel

    1995-06-01

    A model incorporating noise and pump depletion in a Brillouin amplifier (BA) predicts a fundamental limitation on attainable pump-to-signal-ratio extraction efficiency. Experimental data supporting this model are also presented. In spite of the limitation, an experimental technique is shown that results in a factor-of-7 increase in extraction efficiency. We accomplish this by noise suppressing and subsequently double passing a BA. We report an overall power efficiency of 37% and phase-conjugate amplification of 3.75 \\times 1010 for a signal input power near the noise level. This performance, which is the best to our knowledge recorded to date, is accomplished without requiring additional input energy.

  18. Novel Blue Organic Dye for Dye-Sensitized Solar Cells Achieving High Efficiency in Cobalt-Based Electrolytes and by Co-Sensitization.

    PubMed

    Hao, Yan; Saygili, Yasemin; Cong, Jiayan; Eriksson, Anna; Yang, Wenxing; Zhang, Jinbao; Polanski, Enrico; Nonomura, Kazuteru; Zakeeruddin, Shaik Mohammed; Grätzel, Michael; Hagfeldt, Anders; Boschloo, Gerrit

    2016-12-07

    Blue and green dyes as well as NIR-absorbing dyes have attracted great interest because of their excellent ability of absorbing the incident photons in the red and near-infrared range region. A novel blue D-π-A dye (Dyenamo Blue), based on the diketopyrrolopyrrole (DPP)-core, has been designed and synthesized. Assembled with the cobalt bipyridine-based electrolytes, the device with Dyenamo Blue achieved a satisfying efficiency of 7.3% under one sun (AM1.5 G). The co-sensitization strategy was further applied on this blue organic dye together with a red D-π-A dye (D35). The successful co-sensitization outperformed a panchromatic light absorption and improved the photocurrent density; this in addition to the open-circuit potential result in an efficiency of 8.7%. The extended absorption of the sensitization and the slower recombination reaction between the blue dye and TiO2 surface inhibited by the additional red sensitizer could be the two main reasons for the higher performance. In conclusion, from the results, the highly efficient cobalt-based DSSCs could be achieved with the co-sensitization between red and blue D-π-A organic dyes with a proper design, which showed us the possibility of applying this strategy for future high-performance solar cells.

  19. Highly Functional TNTs with Superb Photocatalytic, Optical, and Electronic Performance Achieving Record PV Efficiency of 10.1% for 1D-Based DSSCs.

    PubMed

    Qadir, Muhammad Bilal; Li, Yuewen; Sahito, Iftikhar Ali; Arbab, Alvira Ayoub; Sun, Kyung Chul; Mengal, Naveed; Memon, Anam Ali; Jeong, Sung Hoon

    2016-09-01

    Different nanostructures of TiO2 play an important role in the photocatalytic and photoelectronic applications. TiO2 nanotubes (TNTs) have received increasing attention for these applications due to their unique physicochemical properties. Focusing on highly functional TNTs (HF-TNTs) for photocatalytic and photoelectronic applications, this study describes the facile hydrothermal synthesis of HF-TNTs by using commercial and cheaper materials for cost-effective manufacturing. To prove the functionality and applicability, these TNTs are used as scattering structure in dye-sensitized solar cells (DSSCs). Photocatalytic, optical, Brunauer-Emmett-Teller (BET), electrochemical impedance spectrum, incident-photon-to-current efficiency, and intensity-modulated photocurrent spectroscopy/intensity-modulated photovoltage spectroscopy characterizations are proving the functionality of HF-TNTs for DSSCs. HF-TNTs show 50% higher photocatalytic degradation rate and also 68% higher dye loading ability than conventional TNTs (C-TNTs). The DSSCs having HF-TNT and its composite-based multifunctional overlayer show effective light absorption, outstanding light scattering, lower interfacial resistance, longer electron lifetime, rapid electron transfer, and improved diffusion length, and consequently, J SC , quantum efficiency, and record photoconversion efficiency of 10.1% using commercial N-719 dye is achieved, for 1D-based DSSCs. These new and highly functional TNTs will be a concrete fundamental background toward the development of more functional applications in fuel cells, dye-sensitized solar cells, Li-ion batteries, photocatalysis process, ion-exchange/adsorption process, and photoelectrochemical devices.

  20. Using interlayer step-wise triplet transfer to achieve an efficient white organic light-emitting diode with high color-stability

    SciTech Connect

    Wang, Qi; Ma, Dongge Ding, Junqiao; Wang, Lixiang; Leo, Karl; Qiao, Qiquan; Jia, Huiping; Gnade, Bruce E.

    2014-05-12

    An efficient phosphorescent white organic light emitting-diode with a red-green-blue tri-emitting-layer structure is reported. The host of the red dopant possesses a lower triplet-energy than the green dye. An interlayer step-wise triplet transfer via blue dye → green dye → red host → red dye is achieved. This mechanism allows an efficient triplet harvesting by the three dopants, thus maintaining a balanced white light and reducing energy loss. Moreover, the color stability of the device is improved significantly. The white device not only achieves a peak external quantum efficiency of 21.1 ± 0.8% and power efficiency of 37.5 ± 1.4 lm/W but shows no color shift over a wide range of voltages.

  1. Simple combination of oxidants with zero-valent-iron (ZVI) achieved very rapid and highly efficient removal of heavy metals from water.

    PubMed

    Guo, Xuejun; Yang, Zhe; Dong, Haiyang; Guan, Xiaohong; Ren, Qidong; Lv, Xiaofang; Jin, Xin

    2016-01-01

    This study, for the first time, demonstrated a continuously accelerated Fe(0) corrosion driven by common oxidants (i.e., NaClO, KMnO4 or H2O2) and thereby the rapid and efficient removal of heavy metals (HMs) by zero-valent iron (ZVI) under the experimental conditions of jar tests and column running. ZVI simply coupled with NaClO, KMnO4 or H2O2 (0.5 mM) resulted in almost complete As(V) removal within only 10 min with 1000 μg/L of initial As(V) at initial pH of 7.5(±0.1) and liquid solid ratio of 200:1. Simultaneous removal of 200 μg/L of initial Cd(II) and Hg(II) to 2.4-4.4 μg/L for Cd(II) and to 4.0-5.0 μg/L for Hg(II) were achieved within 30 min. No deterioration of HM removal was observed during the ten recycles of jar tests. The ZVI columns activated by 0.1 mM of oxidants had stably treated 40,200 (NaClO), 20,295 (KMnO4) and 40,200 (H2O2) bed volumes (BV) of HM-contaminated drinking water, but with no any indication of As breakthrough (<10 μg/L) even at short empty bed contact time (EBCT) of 8.0 min. The high efficiency of HMs removal from both the jar tests and column running implied a continuous and stable activation (overcoming of iron passivation) of Fe(0) surface by the oxidants. Via the proper increase in oxidant dosing, the ZVI/oxidant combination was applicable to treat highly As(V)-contaminated wastewater. During Fe(0) surface corrosion accelerated by oxidants, a large amount of fresh and reactive iron oxides and oxyhydroxides were continuously generated, which were responsible for the rapid and efficient removal of HMs through multiple mechanisms including adsorption and co-precipitation. A steady state of Fe(0) surface activation and HM removal enabled this simply coupled system to remove HMs with high speed, efficiency and perdurability.

  2. Bifunctional star-burst amorphous molecular materials for OLEDs: achieving highly efficient solid-state luminescence and carrier transport induced by spontaneous molecular orientation.

    PubMed

    Kim, Jun Yun; Yasuda, Takuma; Yang, Yu Seok; Adachi, Chihaya

    2013-05-21

    Bifunctional star-burst amorphous molecular materials displaying both efficient solid-state luminescence and high hole-transport properties are developed in this study. A high external electroluminescence quantum efficiency up to 5.9% is attained in OLEDs employing the developed amorphous materials. It is revealed that the spontaneous horizontal orientation of these light-emitting molecules in their molecular-condensed states leads to a remarkable enhancement of the electroluminescence efficiencies and carrier-transport properties.

  3. High Efficiency Organic Solar Cells Achieved by the Simultaneous Plasmon-Optical and Plasmon-Electrical Effects from Plasmonic Asymmetric Modes of Gold Nanostars.

    PubMed

    Ren, Xingang; Cheng, Jiaqi; Zhang, Shaoqing; Li, Xinchen; Rao, Tingke; Huo, Lijun; Hou, Jianhui; Choy, Wallace C H

    2016-10-01

    The plasmon-optical effects have been utilized to optically enhance active layer absorption in organic solar cells (OSCs). The exploited plasmonic resonances of metal nanomaterials are typically from the fundamental dipole/high-order modes with narrow spectral widths for regional OSC absorption improvement. The conventional broadband absorption enhancement (using plasmonic effects) needs linear-superposition of plasmonic resonances. In this work, through strategic incorporation of gold nanostars (Au NSs) in between hole transport layer (HTL) and active layer, the excited plasmonic asymmetric modes offer a new approach toward broadband enhancement. Remarkably, the improvement is explained by energy transfer of plasmonic asymmetric modes of Au NS. In more detail, after incorporation of Au NSs, the optical power in electron transport layer transfers to active layer for improving OSC absorption, which otherwise will become dissipation or leakage as the role of carrier transport layer is not for photon-absorption induced carrier generation. Moreover, Au NSs simultaneously deliver plasmon-electrical effects which shorten transport path length of the typically low-mobility holes and lengthen that of high-mobility electrons for better balanced carrier collection. Meanwhile, the resistance of HTL is reduced by Au NSs. Consequently, power conversion efficiency of 10.5% has been achieved through cooperatively plasmon-optical and plasmon-electrical effects of Au NSs.

  4. Achieving High Performance Perovskite Solar Cells

    NASA Astrophysics Data System (ADS)

    Yang, Yang

    2015-03-01

    Recently, metal halide perovskite based solar cell with the characteristics of rather low raw materials cost, great potential for simple process and scalable production, and extreme high power conversion efficiency (PCE), have been highlighted as one of the most competitive technologies for next generation thin film photovoltaic (PV). In UCLA, we have realized an efficient pathway to achieve high performance pervoskite solar cells, where the findings are beneficial to this unique materials/devices system. Our recent progress lies in perovskite film formation, defect passivation, transport materials design, interface engineering with respect to high performance solar cell, as well as the exploration of its applications beyond photovoltaics. These achievements include: 1) development of vapor assisted solution process (VASP) and moisture assisted solution process, which produces perovskite film with improved conformity, high crystallinity, reduced recombination rate, and the resulting high performance; 2) examination of the defects property of perovskite materials, and demonstration of a self-induced passivation approach to reduce carrier recombination; 3) interface engineering based on design of the carrier transport materials and the electrodes, in combination with high quality perovskite film, which delivers 15 ~ 20% PCEs; 4) a novel integration of bulk heterojunction to perovskite solar cell to achieve better light harvest; 5) fabrication of inverted solar cell device with high efficiency and flexibility and 6) exploration the application of perovskite materials to photodetector. Further development in film, device architecture, and interfaces will lead to continuous improved perovskite solar cells and other organic-inorganic hybrid optoelectronics.

  5. Metal-Organic Framework Photosensitized TiO2 Co-catalyst: A Facile Strategy to Achieve a High Efficiency Photocatalytic System.

    PubMed

    Xie, Ming-Hua; Shao, Rong; Xi, Xin-Guo; Hou, Gui-Hua; Guan, Rong-Feng; Dong, Peng-Yu; Zhang, Qin-Fang; Yang, Xiu-Li

    2017-03-17

    A 3D metal-organic framework (ADA-Cd=[Cd2 L2 (DMF)2 ]⋅3 H2 O where H2 L is (2E,2'E)-3,3'-(anthracene-9,10-diyl)diacrylic acid) constructed from diacrylate substituted anthracene, sharing structural characteristics with some frequently employed anthraquinone-type dye sensitizers, was introduced as an effective sensitizer for anatase TiO2 to achieve enhanced visible light photocatalytic performance. A facile mechanical mixing procedure was adopted to prepare the co-catalyst denoted as ADA-Cd/TiO2 , which showed enhanced photodegradation ability, as well as sustainability, towards several dyes under visible light irradiation. Mechanistic studies revealed that ADA-Cd acted as the antenna to harvest visible light energy, generating excited electrons, which were injected to the conduction band (CB) of TiO2 , facilitating the separation efficiency of charge carriers. As suggested by the results of control experiments, combined with the corresponding redox potential of possible oxidative species, (.) O2(-) , generated from the oxygen of ambient air at the CB of TiO2 was believed to play a dominant role over (.) OH and h(+) . UV/Vis and photoluminescence technologies were adopted to monitor the generation of (.) O2(-) and (.) OH, respectively. This work presents a facile strategy to achieve a visible light photocatalyst with enhanced catalytic activity and sustainability; the simplicity, efficiency, and stability of this strategy may provide a promising way to achieve environmental remediation.

  6. Achieving Energy Efficiency Through Real-Time Feedback

    SciTech Connect

    Nesse, Ronald J.

    2011-09-01

    Through the careful implementation of simple behavior change measures, opportunities exist to achieve strategic gains, including greater operational efficiencies, energy cost savings, greater tenant health and ensuing productivity and an improved brand value through sustainability messaging and achievement.

  7. 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.

  8. High Efficiency, Clean Combustion

    SciTech Connect

    Donald Stanton

    2010-03-31

    challenges to reduce oil consumption and greenhouse gases, meet stringent emissions regulations, provide customer value, and improve safety. The HECC program successfully reduced engine fuel consumption and greenhouse gases while providing greater customer valve. The US EPA 2010 emissions standard poses a significant challenge for developing clean diesel powertrains that meet the DoE Vehicle Technologies Multi-Year Program Plan (MYPP) for fuel efficiency improvement while remaining affordable. Along with exhaust emissions, an emphasis on heavy duty vehicle fuel efficiency is being driven by increased energy costs as well as the potential regulation of greenhouse gases. An important element of the success of meeting emissions while significantly improving efficiency is leveraging Cummins component technologies such as fuel injection equipment, aftertreatment, turbomahcinery, electronic controls, and combustion systems. Innovation in component technology coupled with system integration is enabling Cummins to move forward with the development of high efficiency clean diesel products with a long term goal of reaching a 55% peak brake thermal efficiency for the engine plus aftertreatment system. The first step in developing high efficiency clean products has been supported by the DoE co-sponsored HECC program. The objectives of the HECC program are: (1) To design and develop advanced diesel engine architectures capable of achieving US EPA 2010 emission regulations while improving the brake thermal efficiency by 10% compared to the baseline (a state of the art 2007 production diesel engine). (2) To design and develop components and subsystems (fuel systems, air handling, controls, etc) to enable construction and development of multi-cylinder engines. (3) To perform an assessment of the commercial viability of the newly developed engine technology. (4) To specify fuel properties conducive to improvements in emissions, reliability, and fuel efficiency for engines using high-efficiency

  9. Achieving extremely concentrated aqueous dispersions of graphene flakes and catalytically efficient graphene-metal nanoparticle hybrids with flavin mononucleotide as a high-performance stabilizer.

    PubMed

    Ayán-Varela, M; Paredes, J I; Guardia, L; Villar-Rodil, S; Munuera, J M; Díaz-González, M; Fernández-Sánchez, C; Martínez-Alonso, A; Tascón, J M D

    2015-05-20

    The stable dispersion of graphene flakes in an aqueous medium is highly desirable for the development of materials based on this two-dimensional carbon structure, but current production protocols that make use of a number of surfactants typically suffer from limitations regarding graphene concentration or the amount of surfactant required to colloidally stabilize the sheets. Here, we demonstrate that an innocuous and readily available derivative of vitamin B2, namely the sodium salt of flavin mononucleotide (FMNS), is a highly efficient dispersant in the preparation of aqueous dispersions of defect-free, few-layer graphene flakes. Most notably, graphene concentrations in water as high as ∼50 mg mL(-1) using low amounts of FMNS (FMNS/graphene mass ratios of about 0.04) could be attained, which facilitated the formation of free-standing graphene films displaying high electrical conductivity (∼52000 S m(-1)) without the need of carrying out thermal annealing or other types of post-treatment. The excellent performance of FMNS as a graphene dispersant could be attributed to the combined effect of strong adsorption on the sheets through the isoalloxazine moiety of the molecule and efficient colloidal stabilization provided by its negatively charged phosphate group. The FMNS-stabilized graphene sheets could be decorated with nanoparticles of several noble metals (Ag, Pd, and Pt), and the resulting hybrids exhibited a high catalytic activity in the reduction of nitroarenes and electroreduction of oxygen. Overall, the present results should expedite the processing and implementation of graphene in, e.g., conductive inks, composites, and hybrid materials with practical utility in a wide range of applications.

  10. Achieving H.264-like compression efficiency with distributed video coding

    NASA Astrophysics Data System (ADS)

    Milani, Simone; Wang, Jiajun; Ramchandran, Kannan

    2007-01-01

    Recently, a new class of distributed source coding (DSC) based video coders has been proposed to enable low-complexity encoding. However, to date, these low-complexity DSC-based video encoders have been unable to compress as efficiently as motion-compensated predictive coding based video codecs, such as H.264/AVC, due to insufficiently accurate modeling of video data. In this work, we examine achieving H.264-like high compression efficiency with a DSC-based approach without the encoding complexity constraint. The success of H.264/AVC highlights the importance of accurately modeling the highly non-stationary video data through fine-granularity motion estimation. This motivates us to deviate from the popular approach of approaching the Wyner-Ziv bound with sophisticated capacity-achieving channel codes that require long block lengths and high decoding complexity, and instead focus on accurately modeling video data. Such a DSC-based, compression-centric encoder is an important first step towards building a robust DSC-based video coding framework.

  11. Rational design of aggregation-induced emission luminogen with weak electron donor-acceptor interaction to achieve highly efficient undoped bilayer OLEDs.

    PubMed

    Chen, Long; Jiang, Yibin; Nie, Han; Hu, Rongrong; Kwok, Hoi Sing; Huang, Fei; Qin, Anjun; Zhao, Zujin; Tang, Ben Zhong

    2014-10-08

    In this work, two tailored luminogens (TPE-NB and TPE-PNPB) consisting of tetraphenylethene (TPE), diphenylamino, and dimesitylboryl as a π-conjugated linkage, electron donor, and electron acceptor, respectively, are synthesized and characterized. Their thermal stabilities, photophysical properties, solvachromism, fluorescence decays, electronic structures, electrochemical behaviors, and electroluminescence (EL) properties are investigated systematically, and the impacts of electron donor-acceptor (D-A) interaction on optoelectronic properties are discussed. Due to the presence of a TPE unit, both luminogens show aggregation-induced emission, but strong D-A interaction causes a decrease in emission efficiency and red-shifts in photoluminescence and EL emissions. The luminogen, TPE-PNPB, with a weak D-A interaction fluoresces strongly in solid film with a high fluorescence quantum yield of 94%. The trilayer OLED [ITO/NPB (60 nm)/TPE-PNPB (20 nm)/TPBi (40 nm)/LiF (1 nm)/Al (100 nm)] utilizing TPE-PNPB as a light emitter shows a peak luminance of 49 993 cd m(-2) and high EL efficiencies up to 15.7 cd A(-1), 12.9 lm W(-1), and 5.12%. The bilayer OLED [ITO/TPE-PNPB (80 nm)/TPBi (40 nm)/LiF (1 nm)/Al (100 nm)] adopting TPE-PNPB as a light emitter and hole transporter simultaneously affords even better EL efficiencies of 16.2 cd A(-1), 14.4 lm W(-1), and 5.35% in ambient air, revealing that TPE-PNPB is an eximious p-type light emitter.

  12. 10 CFR 433.7 - Water used to achieve energy efficiency. [Reserved

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 10 Energy 3 2013-01-01 2013-01-01 false Water used to achieve energy efficiency. 433.7 Section 433.7 Energy DEPARTMENT OF ENERGY ENERGY CONSERVATION ENERGY EFFICIENCY STANDARDS FOR NEW FEDERAL COMMERCIAL AND MULTI-FAMILY HIGH-RISE RESIDENTIAL BUILDINGS § 433.7 Water used to achieve energy efficiency....

  13. 10 CFR 433.7 - Water used to achieve energy efficiency. [Reserved

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 10 Energy 3 2014-01-01 2014-01-01 false Water used to achieve energy efficiency. 433.7 Section 433.7 Energy DEPARTMENT OF ENERGY ENERGY CONSERVATION ENERGY EFFICIENCY STANDARDS FOR NEW FEDERAL COMMERCIAL AND MULTI-FAMILY HIGH-RISE RESIDENTIAL BUILDINGS § 433.7 Water used to achieve energy efficiency....

  14. 10 CFR 433.7 - Water used to achieve energy efficiency. [Reserved

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 10 Energy 3 2012-01-01 2012-01-01 false Water used to achieve energy efficiency. 433.7 Section 433.7 Energy DEPARTMENT OF ENERGY ENERGY CONSERVATION ENERGY EFFICIENCY STANDARDS FOR NEW FEDERAL COMMERCIAL AND MULTI-FAMILY HIGH-RISE RESIDENTIAL BUILDINGS § 433.7 Water used to achieve energy efficiency....

  15. 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

  16. Highly efficient dye-sensitized solar cells achieved through using Pt-free Nb2O5/C composite counter electrode and iodide-free redox couples

    NASA Astrophysics Data System (ADS)

    Li, Ling; Lu, Qi; Li, Wenyan; Li, Xiaowei; Hagfeldt, Anders; Zhang, Wenming; Wu, Mingxing

    2016-03-01

    To improve the catalytic activity of Nb2O5, a composite Nb2O5/C (Nb2O5 imbedded in carbon support) is synthesized with a simple in situ method and then introduced the composite into dye-sensitized solar cells (DSCs) as a counter electrode (CE) catalyst. Based on the analysis of the cyclic voltammetry, electrochemical impedance spectroscopy, and Tafel-polarization curve measurements, the catalytic activity of the Nb2O5/C composite for the regeneration of iodide-free redox couples of polysulfide (T2/T-) and cobalt complex (Co3+/2+) is indeed enhanced significantly as compared with pure Nb2O5, because the composite electrode eliminates the particle aggregation and forms a mesoporous network structure with large pore size. The T2/T- electrolyte based DSCs with Nb2O5/C CE yields a high power conversion efficiency (PCE) of 6.11%, generating a great improvement of 63.8% as compared to the Pt CE based DSCs. In addition, the Nb2O5/C exhibits higher catalytic activity than Pt for regenerating the Co3+/2+ redox couple and the DSCs using Nb2O5/C CE shows a high PCE of 9.86%.

  17. Use of boron cluster-containing redox nanoparticles with ROS scavenging ability in boron neutron capture therapy to achieve high therapeutic efficiency and low adverse effects.

    PubMed

    Gao, Zhenyu; Horiguchi, Yukichi; Nakai, Kei; Matsumura, Akira; Suzuki, Minoru; Ono, Koji; Nagasaki, Yukio

    2016-10-01

    A boron delivery system with high therapeutic efficiency and low adverse effects is crucial for a successful boron neutron capture therapy (BNCT). In this study, we developed boron cluster-containing redox nanoparticles (BNPs) via polyion complex (PIC) formation, using a newly synthesized poly(ethylene glycol)-polyanion (PEG-polyanion, possessing a (10)B-enriched boron cluster as a side chain of one of its segments) and PEG-polycation (possessing a reactive oxygen species (ROS) scavenger as a side chain of one of its segments). The BNPs exhibited high colloidal stability, selective uptake in tumor cells, specific accumulation, and long retention in tumor tissue and ROS scavenging ability. After thermal neutron irradiation, significant suppression of tumor growth was observed in the BNP-treated group, with only 5-ppm (10)B in tumor tissues, whereas at least 20-ppm (10)B is generally required for low molecular weight (LMW) (10)B agents. In addition, increased leukocyte levels were observed in the LMW (10)B agent-treated group after thermal neutron irradiation, and not in BNP-treated group, which might be attributed to its ROS scavenging ability. No visual metastasis of tumor cells to other organs was observed 1 month after irradiation in the BNP-treated group. These results suggest that BNPs are promising for enhancing the BNCT performance.

  18. The role of the spray pyrolysed Al2O3 barrier layer in achieving high efficiency solar cells on flexible steel substrates

    NASA Astrophysics Data System (ADS)

    Gledhill, Sophie E.; Zykov, Anton; Rissom, Thorsten; Caballero, Raquel; Kaufmann, Christian A.; Fischer, Christian-Herbert; Lux-Steiner, Martha; Efimova, Varvara; Hoffmann, Volker; Oswald, Steffen

    2011-07-01

    Thin film chalcopyrite solar cells grown on light-weight, flexible steel substrates are poised to enter the photovoltaic market. To guarantee good solar cell performance, the diffusion of iron from the steel into the CIGSe absorber material must be hindered during layer deposition. A barrier layer is thus required to isolate the solar module from the metal substrate, both electronically and chemically. Ideally the barrier layer would be deposited by a cheap roll-to-roll process suitable to coat flexible steel substrates. Aluminium oxide deposited by spray pyrolysis matches the criteria. The coating is homogeneous over rough substrates allowing comparatively thin barrier layers to be utilized. In this article, solar cell results are presented contrasting the device performance made with a barrier layer to that without a barrier layer. Secondary Ion Mass spectrometry (SIMS) measurements show that the spray pyrolysed barrier layer diminishes iron diffusion to the chalcopyrite absorber layer. The role of sodium, imperative for the growth of high efficiency chalcopyrite solar cells, and how it interacts with Al2O3 is discussed.

  19. Upside-Down Solar Cell Achieves Record Efficiencies (Fact Sheet)

    SciTech Connect

    Not Available

    2010-12-01

    The inverted metamorphic multijunction (IMM) solar cell is an exercise in efficient innovation - literally, as the technology boasted the highest demonstrated efficiency for converting sunlight into electrical energy at its debut in 2005. Scientists at the National Renewable Energy Laboratory (NREL) inverted the conventional photovoltaic (PV) structure to revolutionary effect, achieving solar conversion efficiencies of 33.8% and 40.8% under one-sun and concentrated conditions, respectively.

  20. 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.

  1. Development of multilayer laminar-type diffraction gratings to achieve high diffraction efficiencies in the 1-8 keV energy region

    NASA Astrophysics Data System (ADS)

    Ishino, Masahiko; Heimann, Philip A.; Sasai, Hiroyuki; Hatayama, Masatoshi; Takenaka, Hisataka; Sano, Kazuo; Gullikson, Eric M.; Koike, Masato

    2006-09-01

    W/C and Co/SiO2 multilayer gratings have been fabricated by depositing a multilayer coating on the surface of laminar-type holographic master gratings. The diffraction efficiency was measured by reflectometers in the energy region of 0.6-8.0 keV at synchrotron radiation facilities as well as with an x-ray diffractometer at 8.05 keV. The Co/SiO2 and W/C multilayer gratings showed peak diffraction efficiencies of 0.47 and 0.38 at 6.0 and 8.0 keV, respectively. To our knowledge, the peak efficiency of the W/C multilayer grating is the highest measured with hard x rays. The diffraction efficiency of the Co/SiO2 multilayer gratings was higher than that of the W/C multilayer grating in the energy range of 2.5-6.0 keV. However, it decreased significantly in the energy above the K absorption edge of Co (7.71 keV). For the Co/SiO2 multilayer grating, the measured diffraction efficiencies agreed with the calculated curves assuming a rms roughness of ˜1 nm.

  2. 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.

  3. The Constraints of Poverty on High Achievement

    ERIC Educational Resources Information Center

    Burney, Virginia H.; Beilke, Jayne R.

    2008-01-01

    Research studies on school success often focus on the impact of discrete elements such as race, culture, ethnicity, gender, language, or school location on high achievement. The condition of poverty, however, may be the most important of all student differences in relation to high achievement; although not all schools have racial diversity, nearly…

  4. Self Regulated Learning of High Achievers

    ERIC Educational Resources Information Center

    Rathod, Ami

    2010-01-01

    The study was conducted on high achievers of Senior Secondary school. Main objectives were to identify the self regulated learners among the high achievers, to find out dominant components and characteristics operative in self regulated learners and to compare self regulated learning of learners with respect to their subject (science and non…

  5. DOD Joint Bases: Management Improvements Needed to Achieve Greater Efficiencies

    DTIC Science & Technology

    2012-11-01

    Joint Bases Realign Fort Eustis, VA, by relocating the installation management functions to Langley AFB, VA. Realign Fort Story , VA, by...the installation management functions to L·mglcy AFB, VA. Realign Fort Story , VA, by relocating the installation management functions to Commander...DOD JOINT BASES Management Improvements Needed to Achieve Greater Efficiencies Report to Congressional Addressees

  6. 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.

  7. 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.

  8. 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.

  9. Systemic Reform and Minority Student High Achievement.

    ERIC Educational Resources Information Center

    Treisman, Philip Uri; Surles, Stephanie A.

    The under-representation of African American and Hispanic American students among high achievers on standardized tests, honors graduates of most colleges, and practitioners of mathematics and science professions is well-documented. This paper explores the extent to which the current educational reform movement is achieving the goal of…

  10. Achieving Energy Efficiency in Accordance with Bioclimatic Architecture Principles

    NASA Astrophysics Data System (ADS)

    Bajcinovci, Bujar; Jerliu, Florina

    2016-12-01

    By using our natural resources, and through inefficient use of energy, we produce much waste that can be recycled as a useful resource, which further contributes to climate change. This study aims to address energy effective bioclimatic architecture principles, by which we can achieve a potential energy savings, estimated at thirty-three per cent, mainly through environmentally affordable reconstruction, resulting in low negative impact on the environment. The study presented in this paper investigated the Ulpiana neighbourhood of Prishtina City, focusing on urban design challenges, energy efficiency and air pollution issues. The research methods consist of empirical observations through the urban spatial area using a comparative method, in order to receive clearer data and information research is conducted within Ulpiana's urban blocks, shapes of architectural structures, with the objective focusing on bioclimatic features in terms of the morphology and microclimate of Ulpiana. Energy supply plays a key role in the economic development of any country, hence, bioclimatic design principles for sustainable architecture and energy efficiency, present an evolutive integrated strategy for achieving efficiency and healthier conditions for Kosovar communities. Conceptual findings indicate that with the integrated design strategy: energy efficiency, and passive bioclimatic principles will result in a bond of complex interrelation between nature, architecture, and community. The aim of this study is to promote structured organized actions to be taken in Prishtina, and Kosovo, which will result in improved energy efficiency in all sectors, and particularly in the residential housing sector.

  11. 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

  12. 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.

  13. 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.

  14. Student Perceptions of High-Achieving Classmates

    ERIC Educational Resources Information Center

    Händel, Marion; Vialle, Wilma; Ziegler, Albert

    2013-01-01

    The reported study investigated students' perceptions of their high-performing classmates in terms of intelligence, social skills, and conscientiousness in different school subjects. The school subjects for study were examined with regard to cognitive, physical, and gender-specific issues. The results show that high academic achievements in…

  15. High Stakes Testing and Student Achievement.

    ERIC Educational Resources Information Center

    Ediger, Marlow

    The effects of high stakes testing may be critical in the lives of public school students and may have many consequences for schools and teachers. There are no easy answers in measuring student achievement and in holding teachers accountable for learner progress. High stakes testing also involves responsibilities on the part of the principal who…

  16. High Achievers: 23rd Annual Survey. Attitudes and Opinions from the Nation's High Achieving Teens.

    ERIC Educational Resources Information Center

    Who's Who among American High School Students, Northbrook, IL.

    This report presents data from an annual survey of high school student leaders and high achievers. It is noted that of the nearly 700,000 high achievers featured in this edition, 5,000 students were sent the survey and 2,092 questionnaires were completed. Subjects were high school juniors and seniors selected for recognition by their principals or…

  17. 10 CFR 433.7 - Water used to achieve energy efficiency. [Reserved

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 10 Energy 3 2011-01-01 2011-01-01 false Water used to achieve energy efficiency. 433.7 Section 433.7 Energy DEPARTMENT OF ENERGY ENERGY CONSERVATION ENERGY EFFICIENCY STANDARDS FOR THE DESIGN AND CONSTRUCTION OF NEW FEDERAL COMMERCIAL AND MULTI-FAMILY HIGH-RISE RESIDENTIAL BUILDINGS § 433.7 Water used...

  18. Some methods for achieving more efficient performance of fuel assemblies

    NASA Astrophysics Data System (ADS)

    Boltenko, E. A.

    2014-07-01

    More efficient operation of reactor plant fuel assemblies can be achieved through the use of new technical solutions aimed at obtaining more uniform distribution of coolant over the fuel assembly section, more intense heat removal on convex heat-transfer surfaces, and higher values of departure from nucleate boiling ratio (DNBR). Technical solutions using which it is possible to obtain more intense heat removal on convex heat-transfer surfaces and higher DNBR values in reactor plant fuel assemblies are considered. An alternative heat removal arrangement is described using which it is possible to obtain a significantly higher power density in a reactor plant and essentially lower maximal fuel rod temperature.

  19. Reliability achievement in high technology space systems

    NASA Technical Reports Server (NTRS)

    Lindstrom, D. L.

    1981-01-01

    The production of failure-free hardware is discussed. The elements required to achieve such hardware are: technical expertise to design, analyze, and fully understand the design; use of high reliability parts and materials control in the manufacturing process; and testing to understand the system and weed out defects. The durability of the Hughes family of satellites is highlighted.

  20. Early predictors of high school mathematics achievement.

    PubMed

    Siegler, Robert S; Duncan, Greg J; Davis-Kean, Pamela E; Duckworth, Kathryn; Claessens, Amy; Engel, Mimi; Susperreguy, Maria Ines; Chen, Meichu

    2012-07-01

    Identifying the types of mathematics content knowledge that are most predictive of students' long-term learning is essential for improving both theories of mathematical development and mathematics education. To identify these types of knowledge, we examined long-term predictors of high school students' knowledge of algebra and overall mathematics achievement. Analyses of large, nationally representative, longitudinal data sets from the United States and the United Kingdom revealed that elementary school students' knowledge of fractions and of division uniquely predicts those students' knowledge of algebra and overall mathematics achievement in high school, 5 or 6 years later, even after statistically controlling for other types of mathematical knowledge, general intellectual ability, working memory, and family income and education. Implications of these findings for understanding and improving mathematics learning are discussed.

  1. Building aggressively duty-cycled platforms to achieve energy efficiency

    NASA Astrophysics Data System (ADS)

    Agarwal, Yuvraj

    Managing power consumption and improving energy efficiency is a key driver in the design of computing devices today. This is true for both battery-powered mobile devices as well as mains-powered desktop PCs and servers. In case of mobile devices, the focus of optimization is on energy efficiency to maximize battery lifetime. In case of mains-powered devices, we seek to optimize power consumption to reduce energy costs, thermal and environmental concerns. Traditionally, there are two main mechanisms to improve energy efficiency in systems: slowdown techniques that seek to reduce processor speed or radio power against the rate of work done, and shutdown techniques that seek to shut down specific components or subsystems -- such as processor, radio, memory -- to reduce power used by these components when not in use. The adverse effect of using these techniques is either reduced performance (e.g., increase in latency) and/or usability or loss of functionality. The thesis behind this dissertation is that improved energy efficiency can be achieved through system architectures that seek to design and exploit "collaboration" among heterogeneous but functionally similar subsystems. For instance, multiple radio interfaces with different power/performance characteristics can collaborate to provide an energy-efficient wireless communication subsystem. Furthermore, we show that in systems where such heterogeneity is not naturally present, we can introduce heterogeneous components to improve overall energy efficiency. We show that using collaboration, individual subsystems and even entire platforms can be shut down more aggressively to reduce energy consumption, while reducing adverse impacts on performance or usability. We have used collaboration to do energy efficient operation in several contexts. For battery powered mobile devices we show that wireless radios are the dominant power consumers, and then describe several techniques that use various heterogeneous radios present

  2. Attitudes and Opinions from the Nation's High Achieving Teens. 18th Annual Survey of High Achievers.

    ERIC Educational Resources Information Center

    Educational Communications, Inc., Lake Forest, IL.

    This document contains factsheets and news releases which cite findings from a national survey of 1,985 high achieving high school students. Factsheets describe the Who's Who Among American High School Students recognition and service program for high school students and explain the Who's Who survey. A summary report of this eighteenth annual…

  3. Gun requirements to achieve high field spheromaks

    SciTech Connect

    Fowler, T K

    1999-03-04

    It is shown that a gun similar to that in the SSPX could demonstrate the high fields required for Pulsed Spheromak reactors merely by prolonging the pulse. Important considerations are choosing the voltage to exceed ohmic losses; designing the gun to avoid wasteful short-circuiting of current within the gun; and the injection efficiency factor, f, determined by the ''sag'' in the profile of {lambda} = {mu}{sub o}j/B. Typically f = 0.75 in experiments, giving an overall efficiency > 50 % if short-circuiting is avoided. Theoretical transport models agree qualitatively with the need for a finite gradient in h to pump in helicity by current-driven tearing modes and suggest that pressure-driven resistive modes would not compete with current-driven modes during a buildup to ohmic ignition.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. Achieving High-Temperature Ferromagnetic Topological Insulator

    NASA Astrophysics Data System (ADS)

    Katmis, Ferhat

    Topological insulators (TIs) are insulating materials that display conducting surface states protected by time-reversal symmetry, wherein electron spins are locked to their momentum. This unique property opens new opportunities for creating next-generation electronic and spintronic devices, including TI-based quantum computation. Introducing ferromagnetic order into a TI system without compromising its distinctive quantum coherent features could lead to a realization of several predicted novel physical phenomena. In particular, achieving robust long-range magnetic order at the TI surface at specific locations without introducing spin scattering centers could open up new possibilities for devices. Here, we demonstrate topologically enhanced interface magnetism by coupling a ferromagnetic insulator (FMI) to a TI (Bi2Se3); this interfacial ferromagnetism persists up to room temperature, even though the FMI (EuS) is known to order ferromagnetically only at low temperatures (<17 K). The induced magnetism at the interface resulting from the large spin-orbit interaction and spin-momentum locking feature of the TI surface is found to greatly enhance the magnetic ordering (Curie) temperature of the TI/FMI bilayer system. Due to the short range nature of the ferromagnetic exchange interaction, the time-reversal symmetry is broken only near the surface of a TI, while leaving its bulk states unaffected. The topological magneto-electric response originating in such an engineered TI could allow for an efficient manipulation of the magnetization dynamics by an electric field, providing an energy efficient topological control mechanism for future spin-based technologies. Work supported by MIT MRSEC through the MRSEC Program of NSF under award number DMR-0819762, NSF Grant DMR-1207469, the ONR Grant N00014-13-1-0301, and the STC Center for Integrated Quantum Materials under NSF grant DMR-1231319.

  9. 22nd Annual Survey of High Achievers: Attitudes and Opinions from the Nation's High Achieving Teens.

    ERIC Educational Resources Information Center

    Who's Who among American High School Students, Northbrook, IL.

    This study surveyed high school students (N=1,879) who were student leaders or high achievers in the spring of 1991 for the purpose of determining their attitudes. Students were members of the junior or senior high school class during the 1990-91 academic year and were selected for recognition by their principals or guidance counselors, other…

  10. 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.

  11. Attitudes and Opinions from the Nation's High Achieving Teens: 26th Annual Survey of High Achievers.

    ERIC Educational Resources Information Center

    Who's Who among American High School Students, Lake Forest, IL.

    A national survey of 3,351 high achieving high school students (junior and senior level) was conducted. All students had A or B averages. Topics covered include lifestyles, political beliefs, violence and entertainment, education, cheating, school violence, sexual violence and date rape, peer pressure, popularity, suicide, drugs and alcohol,…

  12. Attitudes and Opinions from the Nation's High Achieving Teens. 24th Annual Survey of High Achievers.

    ERIC Educational Resources Information Center

    Who's Who among American High School Students, Lake Forest, IL.

    This survey represents information compiled by the largest national survey of adolescent leaders and high achievers. Of the 5,000 students selected demographically from "Who's Who Among American High School Students," 1,957 responded. All students surveyed had "A" or "B" averages, and 98% planned on attending college. Questions were asked about…

  13. 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.

  14. 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.

  15. Towards highly efficient water photoelectrolysis

    NASA Astrophysics Data System (ADS)

    Elavambedu Prakasam, Haripriya

    The motivation for this work was to develop an efficient and relatively inexpensive material architecture suitable for solar water splitting by photoelectrolysis. Iron (III) Oxide (hematite), has bandgap energy (˜ 2.2 eV) well suited for capturing solar spectrum, is abundant and non-toxic. However, it suffers from recombination losses due to low electron mobility and a minority carrier diffusion length of only 2--4 nm. The primary focus of this dissertation was to synthesize thin walled, self-aligned, vertically oriented nanotubular/nanoporous iron (III) oxide structures through electrochemical oxidation. The underlying hypothesis was that thin walled nanotubes would allow charge separation prior to recombination, resulting in a significant increase in the photoelectrochemical properties. Both aqueous and non-aqueous electrolytes were explored as an electrochemical oxidation solvent. Iron oxide film topologies achieved include nanopillar, nanoporous and nanoplatelet structures from aqueous electrolytes, and nanoporous and nanochannel architectures from non-aqueous electrolytes. This dissertation encompasses the first report on synthesis of nanoporous/nanochannel iron (III) oxide structures through potentiostatic anodization, as well as the use of ethylene glycol for the electrochemical oxidation of both iron and titanium. Through control of anodization parameters, including potential and anodization bath composition, excellent control over the morphology and dimensions of the synthesized iron (III) nanostructures have been achieved. As dependent upon the applied potential and electrolytic composition, diameters of the self-aligned nanopores range from 30 nm to 250 nm. The synthesized structures were crystallized in nitrogen ambient to form hematite photoanodes; a maximum photocurrent efficiency of 0.73% was obtained from nanoporous iron (III) oxide synthesized using a glycerol anodization bath. The electrochemical oxidation of titanium in fluoride ion containing

  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. High Involvement Mothers of High Achieving Children: Potential Theoretical Explanations

    ERIC Educational Resources Information Center

    Hunsaker, Scott L.

    2013-01-01

    In American society, parents who have high aspirations for the achievements of their children are often viewed by others in a negative light. Various pejoratives such as "pushy parent," "helicopter parent," "stage mother," and "soccer mom" are used in the common vernacular to describe these parents. Multiple…

  18. Thermodynamic and achievable efficiencies for solar-driven electrochemical reduction of carbon dioxide to transportation fuels

    NASA Astrophysics Data System (ADS)

    Singh, Meenesh R.; Clark, Ezra L.; Bell, Alexis T.

    2015-11-01

    Thermodynamic, achievable, and realistic efficiency limits of solar-driven electrochemical conversion of water and carbon dioxide to fuels are investigated as functions of light-absorber composition and configuration, and catalyst composition. The maximum thermodynamic efficiency at 1-sun illumination for adiabatic electrochemical synthesis of various solar fuels is in the range of 32-42%. Single-, double-, and triple-junction light absorbers are found to be optimal for electrochemical load ranges of 0-0.9 V, 0.9-1.95 V, and 1.95-3.5 V, respectively. Achievable solar-to-fuel (STF) efficiencies are determined using ideal double- and triple-junction light absorbers and the electrochemical load curves for CO2 reduction on silver and copper cathodes, and water oxidation kinetics over iridium oxide. The maximum achievable STF efficiencies for synthesis gas (H2 and CO) and Hythane (H2 and CH4) are 18.4% and 20.3%, respectively. Whereas the realistic STF efficiency of photoelectrochemical cells (PECs) can be as low as 0.8%, tandem PECs and photovoltaic (PV)-electrolyzers can operate at 7.2% under identical operating conditions. We show that the composition and energy content of solar fuels can also be adjusted by tuning the band-gaps of triple-junction light absorbers and/or the ratio of catalyst-to-PV area, and that the synthesis of liquid products and C2H4 have high profitability indices.

  19. Thermodynamic and achievable efficiencies for solar-driven electrochemical reduction of carbon dioxide to transportation fuels.

    PubMed

    Singh, Meenesh R; Clark, Ezra L; Bell, Alexis T

    2015-11-10

    Thermodynamic, achievable, and realistic efficiency limits of solar-driven electrochemical conversion of water and carbon dioxide to fuels are investigated as functions of light-absorber composition and configuration, and catalyst composition. The maximum thermodynamic efficiency at 1-sun illumination for adiabatic electrochemical synthesis of various solar fuels is in the range of 32-42%. Single-, double-, and triple-junction light absorbers are found to be optimal for electrochemical load ranges of 0-0.9 V, 0.9-1.95 V, and 1.95-3.5 V, respectively. Achievable solar-to-fuel (STF) efficiencies are determined using ideal double- and triple-junction light absorbers and the electrochemical load curves for CO2 reduction on silver and copper cathodes, and water oxidation kinetics over iridium oxide. The maximum achievable STF efficiencies for synthesis gas (H2 and CO) and Hythane (H2 and CH4) are 18.4% and 20.3%, respectively. Whereas the realistic STF efficiency of photoelectrochemical cells (PECs) can be as low as 0.8%, tandem PECs and photovoltaic (PV)-electrolyzers can operate at 7.2% under identical operating conditions. We show that the composition and energy content of solar fuels can also be adjusted by tuning the band-gaps of triple-junction light absorbers and/or the ratio of catalyst-to-PV area, and that the synthesis of liquid products and C2H4 have high profitability indices.

  20. Thermodynamic and achievable efficiencies for solar-driven electrochemical reduction of carbon dioxide to transportation fuels

    PubMed Central

    Singh, Meenesh R.; Clark, Ezra L.; Bell, Alexis T.

    2015-01-01

    Thermodynamic, achievable, and realistic efficiency limits of solar-driven electrochemical conversion of water and carbon dioxide to fuels are investigated as functions of light-absorber composition and configuration, and catalyst composition. The maximum thermodynamic efficiency at 1-sun illumination for adiabatic electrochemical synthesis of various solar fuels is in the range of 32–42%. Single-, double-, and triple-junction light absorbers are found to be optimal for electrochemical load ranges of 0–0.9 V, 0.9–1.95 V, and 1.95–3.5 V, respectively. Achievable solar-to-fuel (STF) efficiencies are determined using ideal double- and triple-junction light absorbers and the electrochemical load curves for CO2 reduction on silver and copper cathodes, and water oxidation kinetics over iridium oxide. The maximum achievable STF efficiencies for synthesis gas (H2 and CO) and Hythane (H2 and CH4) are 18.4% and 20.3%, respectively. Whereas the realistic STF efficiency of photoelectrochemical cells (PECs) can be as low as 0.8%, tandem PECs and photovoltaic (PV)-electrolyzers can operate at 7.2% under identical operating conditions. We show that the composition and energy content of solar fuels can also be adjusted by tuning the band-gaps of triple-junction light absorbers and/or the ratio of catalyst-to-PV area, and that the synthesis of liquid products and C2H4 have high profitability indices. PMID:26504215

  1. 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.

  2. 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.

  3. 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.

  4. Air Force Achieves Fuel Efficiency through Industry Best Practices

    SciTech Connect

    2012-12-01

    The U.S. Air Force’s Air Mobility Command (AMC) is changing the way it does business. It is saving energy and money through an aircraft fleet fuel-efficiency program inspired by private industry best practices and ideas resulting from the empowered fuel savings culture.

  5. 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

  6. 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.

  7. Does High School Homework Increase Academic Achievement?

    ERIC Educational Resources Information Center

    Kalenkoski, Charlene Marie; Pabilonia, Sabrina Wulff

    2017-01-01

    Although previous research has shown that homework improves students' academic achievement, the majority of these studies use data on students' homework time from retrospective questionnaires, which may be less accurate than time-diary data. We use data from the combined Child Development Supplement (CDS) and the Transition to Adulthood Survey…

  8. Factors Implicated in High Mathematics Achievement

    ERIC Educational Resources Information Center

    Forgasz, Helen J.; Hill, Janelle C.

    2013-01-01

    The most recent Program for International Student Assessment (PISA) (2009) mathematical literacy results provide evidence that in Western English-speaking countries, including Australia, the gender gap in achievement appears to be widening in favour of males. In the study reported in this article, the aim was to explore the effects of gender,…

  9. High Ability Readers and the Achievement Gap

    ERIC Educational Resources Information Center

    Hunsaker, Scott L.; Parke, Cynthia J.; Bramble, Joan G.

    2004-01-01

    To close the achievement gap, the "No Child Left Behind" law calls for all students to make appropriate yearly progress. This presumably means that progress is being made by capable readers at the same time progress is being made by struggling readers. However, there appear to be unintended effects of "No Child Left Behind"…

  10. 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

  11. Achieving improved cycle efficiency via pressure gain combustors

    SciTech Connect

    Gemmen, R.S.; Janus, M.C.; Richards, G.A.; Norton, T.S.; Rogers, W.A.

    1995-04-01

    As part of the Department of Energy`s Advanced Gas Turbine Systems Program, an investigation is being performed to evaluate ``pressure gain`` combustion systems for gas turbine applications. This paper presents experimental pressure gain and pollutant emission data from such combustion systems. Numerical predictions for certain combustor geometries are also presented. It is reported that for suitable aerovalved pulse combustor geometries studied experimentally, an overall combustor pressure gain of nearly 1 percent can be achieved. It is also shown that for one combustion system operating under typical gas turbine conditions, NO{sub x} and CO emmissions, are about 30 ppmv and 8 ppmv, respectively.

  12. 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..

  13. 10 CFR 433.7 - Water used to achieve energy efficiency. [Reserved

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 10 Energy 3 2010-01-01 2010-01-01 false Water used to achieve energy efficiency. 433.7 Section 433.7 Energy DEPARTMENT OF ENERGY ENERGY CONSERVATION ENERGY EFFICIENCY STANDARDS FOR THE DESIGN AND... achieve energy efficiency....

  14. 10 CFR 435.7 - Water used to achieve energy efficiency. [Reserved

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ...-RISE RESIDENTIAL BUILDINGS Mandatory Energy Efficiency Standards for Federal Low-Rise Residential Buildings. § 435.7 Water used to achieve energy efficiency. ... 10 Energy 3 2011-01-01 2011-01-01 false Water used to achieve energy efficiency. 435.7 Section...

  15. High-Achieving Students in the Era of NCLB

    ERIC Educational Resources Information Center

    Loveless, Tom; Parkas, Steve; Duffett, Ann

    2008-01-01

    This report contains two separate studies examining the status of high-achieving students in the No Child Left Behind (NCLB) era. Part I, An Analysis of NAEP Data, authored by Brookings Institution scholar Tom Loveless, examines achievement trends for high-achieving students (defined, like low-achieving students, by their performance on the…

  16. Achieving Pure Deep-Blue Electroluminescence with CIE y≤0.06 via a Rational Design Approach for Highly Efficient Non-Doped Solution-Processed Organic Light-Emitting Diodes.

    PubMed

    Reddy, Saripally Sudhaker; Sree, Vijaya Gopalan; Cho, Woosum; Jin, Sung-Ho

    2016-11-22

    Deep-blue fluorescent emitters with Commission Internationale de l'Eclairage (CIE) y≤0.06 are urgently needed for high-density storage, full-color displays and solid-state lighting. However, developing such emitters with high color purity and efficiency in solution-processable non-doped organic light-emitting diodes (OLEDs) remains an important challenge. Here, we present the synthesis of two new deep-blue fluorescent emitters (AFpTPI and AFmTPI) based on 10-(9,9-diethyl-9H-fluoren-2-yl)-9,9-dimethyl-9,10-dihydroacridine as a core and 1,3- and/or 1,4-phenylene-linked triphenylimidazole (TPI) analogues for non-doped solution-processable OLEDs. Their thermal, photophysical, electrochemical, and device characteristics are explored, and also strongly supported by density functional theory (DFT) study. AFpTPI and AFmTPI exhibit excellent thermal stability (≈450 °C) with high glass transition temperatures (Tg ; 141-152 °C) and deep-blue emission with high quantum yields. Specifically, the solution-processed non-doped device with AFpTPI as an emitter exhibits a maximum external quantum efficiency (EQE) of 4.56 % with CIE coordinates of (0.15, 0.06), which exactly matches the European Broadcasting Union (EBU) blue standard. In addition, AFmTPI also displays good efficiency and better color purity (EQE: 3.37 %; CIE (0.15, 0.05)). To the best of our knowledge, the present work is the first report on non-doped solution-processable OLEDs with efficiency close to 5 % and CIE y≤0.06.

  17. Barriers to Achieving Textbook Multigrid Efficiency (TME) in CFD

    NASA Technical Reports Server (NTRS)

    Brandt, Achi

    1998-01-01

    As a guide to attaining this optimal performance for general CFD problems, the table below lists every foreseen kind of computational difficulty for achieving that goal, together with the possible ways for resolving that difficulty, their current state of development, and references. Included in the table are staggered and nonstaggered, conservative and nonconservative discretizations of viscous and inviscid, incompressible and compressible flows at various Mach numbers, as well as a simple (algebraic) turbulence model and comments on chemically reacting flows. The listing of associated computational barriers involves: non-alignment of streamlines or sonic characteristics with the grids; recirculating flows; stagnation points; discretization and relaxation on and near shocks and boundaries; far-field artificial boundary conditions; small-scale singularities (meaning important features, such as the complete airplane, which are not visible on some of the coarse grids); large grid aspect ratios; boundary layer resolution; and grid adaption.

  18. 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

  19. 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.

  20. 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

  1. Improving Student Achievement: A Study of High-Poverty Schools with Higher Student Achievement Outcomes

    ERIC Educational Resources Information Center

    Butz, Stephen D.

    2012-01-01

    This research examined the education system at high-poverty schools that had significantly higher student achievement levels as compared to similar schools with lower student achievement levels. A multischool qualitative case study was conducted of the educational systems where there was a significant difference in the scores achieved on the…

  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. Achieving strategic surety for high consequence software

    SciTech Connect

    Pollock, G.M.

    1996-09-01

    A strategic surety roadmap for high consequence software systems under the High Integrity Software (HIS) Program at Sandia National Laboratories guides research in identifying methodologies to improve software surety. Selected research tracks within this roadmap are identified and described detailing current technology and outlining advancements to be pursued over the coming decade to reach HIS goals. The tracks discussed herein focus on Correctness by Design, and System Immunology{trademark}. Specific projects are discussed with greater detail given on projects involving Correct Specification via Visualization, Synthesis, & Analysis; Visualization of Abstract Objects; and Correct Implementation of Components.

  5. Norview High School: Leadership Fosters Achievment

    ERIC Educational Resources Information Center

    Principal Leadership, 2013

    2013-01-01

    Often little unsaid things demonstrate what is truly important in a school. When teachers have common planning time and all of the department chairs share a single space as they do at Norview High School in Norfolk, VA, the unmistakable message is that instructional collaboration and leadership are expected and valued. Norview, an urban,…

  6. 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%.

  7. 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.

  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. Self-Concept and Achievement Motivation of High School Students

    ERIC Educational Resources Information Center

    Lawrence, A. S. Arul; Vimala, A.

    2013-01-01

    The present study "Self-concept and Achievement Motivation of High School Students" was investigated to find the relationship between Self-concept and Achievement Motivation of High School Students. Data for the study were collected using Self-concept Questionnaire developed by Raj Kumar Saraswath (1984) and Achievement Motive Test (ACMT)…

  10. Government Efficiency and Effectiveness: Opportunities to Reduce Fragmentation, Overlap, and Duplication and Achieve Other Financial Benefits

    DTIC Science & Technology

    2015-04-14

    Other Financial Benefits Statement of Gene L. Dodaro Comptroller General of the United States Testimony Before the Committee on Oversight and...Efficiency and Effectiveness: Opportunities to Reduce Fragmentation, Overlap, and Duplication and Achieve Other Financial Benefits 5a. CONTRACT NUMBER 5b...GOVERNMENT EFFICIENCY AND EFFECTIVENESS Opportunities to Reduce Fragmentation, Overlap, and Duplication and Achieve Other Financial Benefits Why

  11. 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.

  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. Lead-Free Inverted Planar Formamidinium Tin Triiodide Perovskite Solar Cells Achieving Power Conversion Efficiencies up to 6.22%

    SciTech Connect

    Liao, Weiqiang; Zhao, Dewei; Yu, Yue; Grice, Corey R.; Wang, Changlei; Cimaroli, Alexander J.; Schulz, Philip; Meng, Weiwei; Zhu, Kai; Xiong, Ren-Gen; Yan, Yanfa

    2016-11-09

    Efficient lead (Pb)-free inverted planar formamidinium tin triiodide (FASnI3) perovskite solar cells (PVSCs) are demonstrated. Our FASnI3 PVSCs achieved average power conversion efficiencies (PCEs) of 5.41% +/- 0.46% and a maximum PCE of 6.22% under forward voltage scan. The PVSCs exhibit small photocurrent-voltage hysteresis and high reproducibility. The champion cell showed a steady-state efficiency of almost equal to 6.00% for over 100 s.

  14. Lead-Free Inverted Planar Formamidinium Tin Triiodide Perovskite Solar Cells Achieving Power Conversion Efficiencies up to 6.22.

    PubMed

    Liao, Weiqiang; Zhao, Dewei; Yu, Yue; Grice, Corey R; Wang, Changlei; Cimaroli, Alexander J; Schulz, Philip; Meng, Weiwei; Zhu, Kai; Xiong, Ren-Gen; Yan, Yanfa

    2016-11-01

    Efficient lead (Pb)-free inverted planar formamidinium tin triiodide (FASnI3 ) perovskite solar cells (PVSCs) are demonstrated. Our FASnI3 PVSCs achieved average power conversion efficiencies (PCEs) of 5.41% ± 0.46% and a maximum PCE of 6.22% under forward voltage scan. The PVSCs exhibit small photocurrent-voltage hysteresis and high reproducibility. The champion cell shows a steady-state efficiency of ≈6.00% for over 100 s.

  15. 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.

  16. Energy efficiency enhancements for semiconductors, communications, sensors and software achieved in cool silicon cluster project

    NASA Astrophysics Data System (ADS)

    Ellinger, Frank; Mikolajick, Thomas; Fettweis, Gerhard; Hentschel, Dieter; Kolodinski, Sabine; Warnecke, Helmut; Reppe, Thomas; Tzschoppe, Christoph; Dohl, Jan; Carta, Corrado; Fritsche, David; Tretter, Gregor; Wiatr, Maciej; Detlef Kronholz, Stefan; Mikalo, Ricardo Pablo; Heinrich, Harald; Paulo, Robert; Wolf, Robert; Hübner, Johannes; Waltsgott, Johannes; Meißner, Klaus; Richter, Robert; Michler, Oliver; Bausinger, Markus; Mehlich, Heiko; Hahmann, Martin; Möller, Henning; Wiemer, Maik; Holland, Hans-Jürgen; Gärtner, Roberto; Schubert, Stefan; Richter, Alexander; Strobel, Axel; Fehske, Albrecht; Cech, Sebastian; Aßmann, Uwe; Pawlak, Andreas; Schröter, Michael; Finger, Wolfgang; Schumann, Stefan; Höppner, Sebastian; Walter, Dennis; Eisenreich, Holger; Schüffny, René

    2013-07-01

    An overview about the German cluster project Cool Silicon aiming at increasing the energy efficiency for semiconductors, communications, sensors and software is presented. Examples for achievements are: 1000 times reduced gate leakage in transistors using high-fc (HKMG) materials compared to conventional poly-gate (SiON) devices at the same technology node; 700 V transistors integrated in standard 0.35 μm CMOS; solar cell efficiencies above 19% at < 200 W/m2 irradiation; 0.99 power factor, 87% efficiency and 0.088 distortion factor for dc supplies; 1 ns synchronization resolution via Ethernet; database accelerators allowing 85% energy savings for servers; adaptive software yielding energy reduction of 73% for e-Commerce applications; processors and corresponding data links with 40% and 70% energy savings, respectively, by adaption of clock frequency and supply voltage in less than 20 ns; clock generator chip with tunable frequency from 83-666 MHz and 0.62-1.6 mW dc power; 90 Gb/s on-chip link over 6 mm and efficiency of 174 fJ/mm; dynamic biasing system doubling efficiency in power amplifiers; 60 GHz BiCMOS frontends with dc power to bandwidth ratio of 0.17 mW/MHz; driver assistance systems reducing energy consumption by 10% in cars Contribution to the Topical Issue “International Semiconductor Conference Dresden-Grenoble - ISCDG 2012”, Edited by Gérard Ghibaudo, Francis Balestra and Simon Deleonibus.

  17. 10 CFR 435.7 - Water used to achieve energy efficiency. [Reserved

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 10 Energy 3 2010-01-01 2010-01-01 false Water used to achieve energy efficiency. 435.7 Section 435.7 Energy DEPARTMENT OF ENERGY ENERGY CONSERVATION ENERGY EFFICIENCY STANDARDS FOR NEW FEDERAL LOW-RISE RESIDENTIAL BUILDINGS Mandatory Energy Efficiency Standards for Federal Low-Rise...

  18. 10 CFR 435.7 - Water used to achieve energy efficiency. [Reserved

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 10 Energy 3 2014-01-01 2014-01-01 false Water used to achieve energy efficiency. 435.7 Section 435.7 Energy DEPARTMENT OF ENERGY ENERGY CONSERVATION ENERGY EFFICIENCY STANDARDS FOR NEW FEDERAL LOW-RISE RESIDENTIAL BUILDINGS Mandatory Energy Efficiency Standards for Federal Low-Rise...

  19. 10 CFR 435.7 - Water used to achieve energy efficiency. [Reserved

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 10 Energy 3 2012-01-01 2012-01-01 false Water used to achieve energy efficiency. 435.7 Section 435.7 Energy DEPARTMENT OF ENERGY ENERGY CONSERVATION ENERGY EFFICIENCY STANDARDS FOR NEW FEDERAL LOW-RISE RESIDENTIAL BUILDINGS Mandatory Energy Efficiency Standards for Federal Low-Rise...

  20. 10 CFR 435.7 - Water used to achieve energy efficiency. [Reserved

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 10 Energy 3 2013-01-01 2013-01-01 false Water used to achieve energy efficiency. 435.7 Section 435.7 Energy DEPARTMENT OF ENERGY ENERGY CONSERVATION ENERGY EFFICIENCY STANDARDS FOR NEW FEDERAL LOW-RISE RESIDENTIAL BUILDINGS Mandatory Energy Efficiency Standards for Federal Low-Rise...

  1. 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.

  2. 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.

  3. 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).

  4. Scientific Temper among Academically High and Low Achieving Adolescent Girls

    ERIC Educational Resources Information Center

    Kour, Sunmeet

    2015-01-01

    The present study was undertaken to compare the scientific temper of high and low achieving adolescent girl students. Random sampling technique was used to draw the sample from various high schools of District Srinagar. The sample for the present study consisted of 120 school going adolescent girls (60 high and 60 low achievers). Data was…

  5. 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%.

  6. 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.

  7. 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.

  8. 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.

  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 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.

  11. 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.

  12. The "Renaissance Child": High Achievement and Gender in Late Modernity

    ERIC Educational Resources Information Center

    Skelton, Christine; Francis, Becky

    2012-01-01

    This paper draws on the concept of the "Renaissance Child" to illustrate the ways in which gender influences the opportunities and possibilities of high-achieving pupils. Using data from a study of 12-13-year high-achieving boys and girls based in schools in England, the paper considers the ways in which a group of popular boys was able…

  13. 12 New England Organizations Honored for Outstanding Achievements in Energy Efficiency

    EPA Pesticide Factsheets

    EPA and the U.S. Department of Energy (DOE) are honoring 12 New England businesses and organizations for their commitment to saving energy, saving money, and protecting the environment through superior energy efficiency achievements.

  14. 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

  15. 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.

  16. 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.

  17. 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.

  18. 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…

  19. 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.

  20. 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

  1. Test-Taking Strategies of High and Low Mathematics Achievers

    ERIC Educational Resources Information Center

    Hong, Eunsook; Sas, Maggie; Sas, John C.

    2006-01-01

    The authors explored test-preparation and test-taking strategies that high school students used in algebra tests. From a pool of high school students (N = 156), 61 students participated in interviews, and of those interviewed, 26 represented those who were high achieving as well as highly interested in mathematics (n = 15) vs. those who were low…

  2. Evaluating performance of high efficiency mist eliminators

    SciTech Connect

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

    2013-07-01

    material on each element at final dP. Plots of overall filtering efficiencies for DOP (spherical aerosol) and dry surrogate (aspherical aerosols) at specified dPs were computed for each filter. Filtering efficiencies were determined as a function of particle size. Curves were also generated showing the most penetrating particle size as a function of dP. A preliminary set of tests was conducted to evaluate spray location, duration, pressure, and wash volume for in-place cleaning the interior surface (reducing dP) of the HEME element. A variety of nozzle designs were evaluated and test results demonstrated the potential to overload the HEME (saturate filter medium) resulting in very high dPs and extensive drain times. At least one combination of spray nozzle design, spray location on the surface of the element, and spray time/pressure was successful in achieving extension of operational life. (authors)

  3. Some Correlates of High School Foreign Language Achievement.

    ERIC Educational Resources Information Center

    Beanblossom, Gary F.

    This paper investigates the influences of traditional kinds of verbal and quantitative achievement and aptitude variables on high school foreign language achievement, as measured by Modern Language Association and University of Washington tests of language skills administered to entering college students. The report focuses on: (1) the sample and…

  4. Attitudes and Opinions from the Nation's High Achieving Teens: 29th Annual Survey of High Achievers.

    ERIC Educational Resources Information Center

    Who's Who among American High School Students, Lake Forest, IL.

    This report presents the 1998 statistical findings of the annual survey to determine the attitudes of national high school student leaders. Questionnaires were completed by 3,123 high school juniors and seniors, all of whom were selected for recognition in "Who's Who among American High School Students." In addition to demographic…

  5. 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.

  6. 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.

  7. Achievement Motivation Training for Potential High School Dropouts. Achievement Motivation Development Project Working Paper Number 4.

    ERIC Educational Resources Information Center

    McClelland, David C.

    This pilot project sought to determine if instruction in achievement motivation would help potential dropouts to complete their schooling. Subjects were tenth grade students in a suburban Boston high school. A one-week residential course during winter and spring vacations was taken by one group of six boys and a second group of four. Equated…

  8. Attitudes and Opinions from the Nation's High Achieving Teens: 28th Annual Survey of High Achievers.

    ERIC Educational Resources Information Center

    Who's Who among American High School Students, Lake Forest, IL.

    This report details the 28th annual study to examine the attitudes of student leaders in U.S. high schools. Participating in the survey were 3,210 adolescents, primarily 16- and 17-year-olds, who had been featured in the 1997 edition of "Who's Who Among American High School Students." The report presents demographic information on the…

  9. Attitudes and Opinions from the Nation's High Achieving Teens: 27th Annual Survey of High Achievers.

    ERIC Educational Resources Information Center

    Who's Who among American High School Students, Lake Forest, IL.

    This report details the 27th annual study to examine the attitudes of student leaders in U.S. high schools. Participating in the survey were 3,370 adolescents, primarily 16- and 17-year-olds, who had been featured in the 1996 edition of "Who's Who Among American High School Students." The report presents demographic information on the survey…

  10. 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

  11. 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.

  12. 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.

  13. 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.

  14. Attitudes and Opinions from the Nation's High Achieving Teens. 25th Annual Survey of High Achievers.

    ERIC Educational Resources Information Center

    Who's Who among American High School Students, Lake Forest, IL.

    This survey was conducted during the spring of 1994 for the purpose of determining the attitudes of student leaders in the nation's high schools. Eight thousand surveys were sent out to students, of which 3177 were returned. All students surveyed were members of the junior or senior class during the 1993-94 academic year. They were selected for…

  15. 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.

  16. What Does Quality Programming Mean for High Achieving Students?

    ERIC Educational Resources Information Center

    Samudzi, Cleo

    2008-01-01

    The Missouri Academy of Science, Mathematics and Computing (Missouri Academy) is a two-year accelerated, early-entrance-to-college, residential school that matches the level, complexity and pace of the curriculum with the readiness and motivation of high achieving high school students. The school is a part of Northwest Missouri State University…

  17. High School Employment and Academic Achievement: A Note for Educators

    ERIC Educational Resources Information Center

    Keister, Mary; Hall, Joshua

    2010-01-01

    Educators are often in a position to affect student decisions to work during the school term. This study reviews and summarizes the literature on the effect that employment during high school has on academic achievement. The available evidence suggests that part-time jobs for high school students are beneficial as long as the number of hours…

  18. High-Stakes Testing: Does It Increase Achievement?

    ERIC Educational Resources Information Center

    Nichols, Sharon L.

    2007-01-01

    I review the literature on the impact on student achievement of high-stakes testing. Its popularity as a mechanism for holding educators accountable has triggered studies to examine whether its promise to increase student learning has been fulfilled. The review concludes there is no consistent evidence to suggest high-stakes testing leads to…

  19. Brain Hemisphericity and Mathematics Achievement of High School Students

    ERIC Educational Resources Information Center

    Fernandez, Sanny F.

    2011-01-01

    This study aimed to find out the brain hemisphericity and mathematics achievement of high school students. The respondents of the study were the 168 first year high school students of Colegio de San Jose, during school year 2010-2011 who were chosen through stratified random sampling. The descriptive and interview methods of research were used in…

  20. Exploring High-Achieving Students' Images of Mathematicians

    ERIC Educational Resources Information Center

    Aguilar, Mario Sánchez; Rosas, Alejandro; Zavaleta, Juan Gabriel Molina; Romo-Vázquez, Avenilde

    2016-01-01

    The aim of this study is to describe the images that a group of high-achieving Mexican students hold of mathematicians. For this investigation, we used a research method based on the Draw-A-Scientist Test (DAST) with a sample of 63 Mexican high school students. The group of students' pictorial and written descriptions of mathematicians assisted us…

  1. 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.

  2. 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.

  3. 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.

  4. Achieving the College Dream? Examining Disparities in Access to College Information among High Achieving and Non-High Achieving Latina Students

    ERIC Educational Resources Information Center

    Kimura-Walsh, Erin; Yamamura, Erica K.; Griffin, Kimberly A.; Allen, Walter R.

    2009-01-01

    Using an Opportunity to Learn (OTL) framework, this study examines the college preparatory experiences of Latina high and non-high achievers at an urban Latina/o majority high school. Findings indicate that students relied almost exclusively on school resources to navigate their college preparation process. However, the school provided…

  5. 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

  6. 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

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. Self-Esteem and Academic Achievement of High School Students

    ERIC Educational Resources Information Center

    Moradi Sheykhjan, Tohid; Jabari, Kamran; Rajeswari, K.

    2014-01-01

    The primary purpose of this study was to determine the influence of self-esteem on academic achievement among high school students in Miandoab City of Iran. The methodology of the research is descriptive and correlation that descriptive and inferential statistics were used to analyze the data. Statistical Society includes male and female high…

  12. Comparison of Achievement of Students in High School Courses

    ERIC Educational Resources Information Center

    Troxel, Verne A.

    1970-01-01

    Compares student achievements on common objectives of CHEMS, CBA, and "Modern Chemistry high school chemistry courses. Results indicate the three couses are not equally effective in meeting their objectives. CHEMS and CBA develop a better understanding of chemistry and science, as well as develop greater ability for critical thinking. CBA…

  13. Relationship between High School Leadership Team Practices and Student Achievement

    ERIC Educational Resources Information Center

    McInnis, Timothy M.

    2009-01-01

    This study investigated if a relationship existed between student achievement in 10th grade Missouri Assessment Program mathematics and 11th grade communication arts scores in 2007 and high school leadership team perceptions of the extent to which they demonstrated leadership practices. The secondary purpose was to compare perceptional…

  14. Early College High School: Closing the Latino Achievement Gap

    ERIC Educational Resources Information Center

    Beall, Kristen Ann

    2016-01-01

    The population of United States Latino students is growing at a rapid rate but their academic achievement lags behind white and Asian students. This issue has significant consequences for the nation's economy, as the job market continues to demand more education and better skills. Early College High School programs have the potential to improve…

  15. A Hybrid Adenoviral Vector System Achieves Efficient Long-Term Gene Expression in the Liver via piggyBac Transposition

    PubMed Central

    Smith, Ryan P.; Riordan, Jesse D.; Feddersen, Charlotte R.

    2015-01-01

    Abstract Much research has gone into the development of hybrid gene delivery systems that combine the broad tropism and efficient transduction of adenoviral vectors with the ability to achieve stable expression of cargo genes. In addition to gene therapy applications, such a system has considerable advantages for studies of gene function in vivo, permitting fine-tuned genetic manipulation with higher throughput than can be achieved using standard transgenic and DNA targeting techniques. Existing strategies are limited, however, by low integration efficiencies, small cargo capacity, and/or a dependence on target cell division. The utility of this approach could be enhanced by a system that provides all of the following: (1) efficient delivery, (2) stable expression in a high percentage of target cells (whether mitotic or not), (3) large cargo capacity, (4) flexibility to use with a wide range of additional experimental conditions, and (5) simple experimental technique. Here we report the initial characterization of a hybrid system that meets these criteria by utilizing piggyBac (PB) transposition to achieve genomic integration from adenoviral vectors. We demonstrate stable expression of an adenovirus (Ad)-PB-delivered reporter gene in ∼20–40% of hepatocytes following standard tail vein injection. Its high efficiency and flexibility relative to existing hybrid adenoviral gene delivery approaches indicate a considerable potential utility of the Ad-PB system for therapeutic gene delivery and in vivo studies of gene function. PMID:25808258

  16. 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

  17. 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

  18. 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.

  19. 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.

  20. 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.

  1. High-efficiency antibody discovery achieved with multiplexed microscopy.

    PubMed

    Mettler Izquierdo, Shelley; Varela, Stephanie; Park, Minha; Collarini, Ellen J; Lu, Daniel; Pramanick, Shreya; Rucker, Joseph; Lopalco, Lucia; Etches, Rob; Harriman, William

    2016-08-01

    The analysis of secreted antibody from large and diverse populations of B cells in parallel at the clonal level can reveal desirable antibodies for diagnostic or therapeutic applications. By immobilizing B cells in microdroplets with particulate reporters, decoding and isolating them in a microscopy environment, we have recovered panels of antibodies with rare attributes to therapeutically relevant targets. The ability to screen up to 100 million cells in a single experiment can be fully leveraged by accessing primary B-cell populations from evolutionarily divergent species such as chickens.

  2. Ternary Polymer Solar Cells based on Two Acceptors and One Donor for Achieving 12.2% Efficiency.

    PubMed

    Zhao, Wenchao; Li, Sunsun; Zhang, Shaoqing; Liu, Xiaoyu; Hou, Jianhui

    2017-01-01

    Ternary polymer solar cells are fabricated based on one donor PBDB-T and two acceptors (a methyl-modified small-molecular acceptor (IT-M) and a bis-adduct of Bis[70]PCBM). A high power conversion efficiency of 12.2% can be achieved. The photovoltaic performance of the ternary polymer solar cells is not sensitive to the composition of the blend.

  3. 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.

  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 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

  6. Parent Involvement Practices of High-Achieving Elementary Science Students

    NASA Astrophysics Data System (ADS)

    Waller, Samara Susan

    This study addressed a prevalence of low achievement in science courses in an urban school district in Georgia. National leaders and educators have identified the improvement of science proficiency as critical to the future of American industry. The purpose of this study was to examine parent involvement in this school district and its contribution to the academic achievement of successful science students. Social capital theory guided this study by suggesting that students achieve best when investments are made into their academic and social development. A collective case study qualitative research design was used to interview 9 parent participants at 2 elementary schools whose children scored in the exceeds category on the Science CRCT. The research questions focused on what these parents did at home to support their children's academic achievement. Data were collected using a semi-structured interview protocol and analyzed through the categorical aggregation of transcribed interviews. Key findings revealed that the parents invested time and resources in 3 practices: communicating high expectations, supporting and developing key skills, and communicating with teachers. These findings contribute to social change at both the local and community level by creating a starting point for teachers, principals, and district leaders to reexamine the value of parent input in the educational process, and by providing data to support the revision of current parent involvement policies. Possibilities for further study building upon the findings of this study may focus on student perceptions of their parents' parenting as it relates to their science achievement.

  7. The Construction of Black High-Achiever Identities in a Predominantly White High School

    ERIC Educational Resources Information Center

    Andrews, Dorinda J. Carter

    2009-01-01

    In this article, I examine how black students construct their racial and achievement self-concepts in a predominantly white high school to enact a black achiever identity. By listening to these students talk about the importance of race and achievement to their lives, I came to understand how racialized the task of achieving was for them even…

  8. Improving science achievement at high-poverty urban middle schools

    NASA Astrophysics Data System (ADS)

    Ruby, Allen

    2006-11-01

    A large percentage of U.S. students attending high-poverty urban middle schools achieve low levels of science proficiency, posing significant challenges to their success in high school science and to national and local efforts to reform science education. Through its work in Philadelphia schools, the Center for Social Organization of Schools at Johns Hopkins University developed a teacher-support model to address variation in science curricula, lack of materials, and underprepared teachers that combined with initial low levels of proficiency block improvements in science achievement. The model includes a common science curriculum based on NSF-supported materials commercially available, ongoing teacher professional development built around day-to-day lessons, and regular in-class support of teachers by expert peer coaches. One cohort of students at three Philadelphia middle schools using the model was followed from the end of fourth grade through seventh grade. Their gains in science achievement and achievement levels were substantially greater than students at 3 matched control schools and the 23 district middle schools serving a similar student population. Under school-by-school comparisons, these results held for the two schools with adequate implementation. Using widely available materials and techniques, the model can be adopted and modified by school partners and districts.

  9. The Will to Achieve: A Phenomenological Study of the Experiences of African American High Achieving Students and Their Parents

    ERIC Educational Resources Information Center

    Spencer, Natalie Faye

    2012-01-01

    The purpose of this research study was to understand the experiences of high achieving African American students and their parents. The experiences of high achieving African American students and their parents have been missing from literature on the academic achievement of African American students. Much of the literature that has been published…

  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. Achieving High Performance on the i860 Microprocessor

    NASA Technical Reports Server (NTRS)

    Lee, King; Kutler, Paul (Technical Monitor)

    1998-01-01

    The i860 is a high performance microprocessor used in the Intel Touchstone project. This paper proposes a paradigm for programming the i860 that is modelled on the vector instructions of the Cray computers. Fortran callable assembler subroutines were written that mimic the concurrent vector instructions of the Cray. Cache takes the place of vector registers. Using this paradigm we have achieved twice the performance of compiled code on a traditional solve.

  12. 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.

  13. 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.

  14. 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.

  15. 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)

  16. 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.

  17. Device engineering of perovskite solar cells to achieve near ideal efficiency

    SciTech Connect

    Agarwal, Sumanshu E-mail: prnair@ee.iitb.ac.in; Nair, Pradeep R. E-mail: prnair@ee.iitb.ac.in

    2015-09-21

    Despite the exciting recent research on perovskite based solar cells, the design space for further optimization and the practical limits of efficiency are not well known in the community. In this letter, we address these aspects through theoretical calculations and detailed numerical simulations. Here, we first provide the detailed balance limit efficiency in the presence of radiative and Auger recombination. Then, using coupled optical and carrier transport simulations, we identify the physical mechanisms that contribute towards bias dependent carrier collection, and hence low fill factors of current perovskite based solar cells. Our detailed simulations indicate that it is indeed possible to achieve efficiencies and fill factors greater than 25% and 85%, respectively, with near ideal super-position characteristics even in the presence of Auger recombination.

  18. Device engineering of perovskite solar cells to achieve near ideal efficiency

    NASA Astrophysics Data System (ADS)

    Agarwal, Sumanshu; Nair, Pradeep R.

    2015-09-01

    Despite the exciting recent research on perovskite based solar cells, the design space for further optimization and the practical limits of efficiency are not well known in the community. In this letter, we address these aspects through theoretical calculations and detailed numerical simulations. Here, we first provide the detailed balance limit efficiency in the presence of radiative and Auger recombination. Then, using coupled optical and carrier transport simulations, we identify the physical mechanisms that contribute towards bias dependent carrier collection, and hence low fill factors of current perovskite based solar cells. Our detailed simulations indicate that it is indeed possible to achieve efficiencies and fill factors greater than 25% and 85%, respectively, with near ideal super-position characteristics even in the presence of Auger recombination.

  19. 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

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. 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

  5. Deep-ultraviolet light-emitting diodes with external quantum efficiency higher than 20% at 275 nm achieved by improving light-extraction efficiency

    NASA Astrophysics Data System (ADS)

    Takano, Takayoshi; Mino, Takuya; Sakai, Jun; Noguchi, Norimichi; Tsubaki, Kenji; Hirayama, Hideki

    2017-03-01

    Enhancing the light-extraction efficiency is the key issue for realizing highly efficient AlGaN-based ultraviolet light-emitting diodes (UV-LEDs). We introduced several features to improve the light extraction: a transparent AlGaN:Mg contact layer, a Rh mirror electrode, an AlN template on a patterned sapphire substrate, and encapsulation resin. The combination of the AlGaN:Mg contact layer and the Rh mirror electrode significantly improved the output power and the external quantum efficiency (EQE) of UV-LEDs. By introducing the aforementioned features, a maximum EQE of >20% at an emission wavelength of 275 nm and a 20-mA direct current was achieved.

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

    ERIC Educational Resources Information Center

    Milburn, Kristine M.

    2011-01-01

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

  7. 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

  8. 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.

  9. Interface Strategy To Achieve Tunable High Frequency Attenuation.

    PubMed

    Lv, Hualiang; Zhang, Haiqian; Ji, Guangbin; Xu, Zhichuan J

    2016-03-01

    Among all polarizations, the interface polarization effect is the most effective, especially at high frequency. The design of various ferrite/iron interfaces can significantly enhance the materials' dielectric loss ability at high frequency. This paper presents a simple method to generate ferrite/iron interfaces to enhance the microwave attenuation at high frequency. The ferrites were coated onto carbonyl iron and could be varied to ZnFe2O4, CoFe2O4, Fe3O4, and NiFe2O4. Due to the ferrite/iron interface inducing a stronger dielectric loss effect, all of these materials achieved broad effective frequency width at a coating layer as thin as 1.5 mm. In particular, an effective frequency width of 6.2 GHz could be gained from the Fe@NiFe2O4 composite.

  10. 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.

  11. 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.

  12. Unlocking Emergent Talent: Supporting High Achievement of Low-Income, High Ability Students

    ERIC Educational Resources Information Center

    Olszewski-Kubilius, Paula; Clarenbach, Jane

    2012-01-01

    This report takes a comprehensive look at achievement for low-income promising learners--past, present, and future. At its core, it challenges the nation to move beyond its near-singular focus of achieving minimum performance for all students, to identifying and developing the talent of all students who are capable of high achievement, including…

  13. 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

  14. 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.

  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. 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.

  17. 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.

  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. 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.

  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, 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.

  1. 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.

  2. 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.

  3. 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.

  4. An Efficient Wireless Recharging Mechanism for Achieving Perpetual Lifetime of Wireless Sensor Networks

    PubMed Central

    Yu, Hongli; Chen, Guilin; Zhao, Shenghui; Chang, Chih-Yung; Chin, Yu-Ting

    2016-01-01

    Energy recharging has received much attention in recent years. Several recharging mechanisms were proposed for achieving perpetual lifetime of a given Wireless Sensor Network (WSN). However, most of them require a mobile recharger to visit each sensor and then perform the recharging task, which increases the length of the recharging path. Another common weakness of these works is the requirement for the mobile recharger to stop at the location of each sensor. As a result, it is impossible for recharger to move with a constant speed, leading to inefficient movement. To improve the recharging efficiency, this paper takes “recharging while moving” into consideration when constructing the recharging path. We propose a Recharging Path Construction (RPC) mechanism, which enables the mobile recharger to recharge all sensors using a constant speed, aiming to minimize the length of recharging path and improve the recharging efficiency while achieving the requirement of perpetual network lifetime of a given WSN. Performance studies reveal that the proposed RPC outperforms existing proposals in terms of path length and energy utilization index, as well as visiting cycle. PMID:28025567

  5. An Efficient Wireless Recharging Mechanism for Achieving Perpetual Lifetime of Wireless Sensor Networks.

    PubMed

    Yu, Hongli; Chen, Guilin; Zhao, Shenghui; Chang, Chih-Yung; Chin, Yu-Ting

    2016-12-23

    Energy recharging has received much attention in recent years. Several recharging mechanisms were proposed for achieving perpetual lifetime of a given Wireless Sensor Network (WSN). However, most of them require a mobile recharger to visit each sensor and then perform the recharging task, which increases the length of the recharging path. Another common weakness of these works is the requirement for the mobile recharger to stop at the location of each sensor. As a result, it is impossible for recharger to move with a constant speed, leading to inefficient movement. To improve the recharging efficiency, this paper takes "recharging while moving" into consideration when constructing the recharging path. We propose a Recharging Path Construction (RPC) mechanism, which enables the mobile recharger to recharge all sensors using a constant speed, aiming to minimize the length of recharging path and improve the recharging efficiency while achieving the requirement of perpetual network lifetime of a given WSN. Performance studies reveal that the proposed RPC outperforms existing proposals in terms of path length and energy utilization index, as well as visiting cycle.

  6. 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.

  7. Achieving unusual oxidation state of matter under high pressure

    NASA Astrophysics Data System (ADS)

    Wang, Xiaoli; Lin, Haiqing; Ma, Yanming; Miao, Maosheng

    2013-03-01

    Pressure has many effects to matter including the reduction of the volume, the increase of the coordination number and the broadening of the band-widths. In the past, most of the high-pressure studies focused on structural and electronic state phase transitions. Using first principles calculations and a bias-free structural search method, we will demonstrate that high pressure can lead to high oxidation state of elements that can never be achieved under ambient condition, making high pressure technique a nice tool to explore many traditional topics in solid state and molecular chemistry. As an example, we will show that Hg can transfer the electrons in its outmost d shell to F atoms and form HgF4 molecular crystals under pressure, thereby acting as a true transition metal. Group IIB elements, including Zn, Cd, and Hg are usually defined as post-transition metals because they are commonly oxidized only to the +2 state. Their d shells are completely filled and do not participate in the formation of chemical bonds. Although the synthesis of HgF4 molecules in gas phase was reported before, the molecules show strong instabilities and dissociate. Therefore, the transition metal propensity of Hg remains an open question.

  8. Alternative Formats to Achieve More Efficient Energy Codes for Commercial Buildings

    SciTech Connect

    Conover, David R.; Rosenberg, Michael I.; Halverson, Mark A.; Taylor, Zachary T.; Makela, Eric J.

    2013-01-26

    This paper identifies and examines several formats or structures that could be used to create the next generation of more efficient energy codes and standards for commercial buildings. Pacific Northwest National Laboratory (PNNL) is funded by the U.S. Department of Energy’s Building Energy Codes Program (BECP) to provide technical support to the development of ANSI/ASHRAE/IES Standard 90.1. While the majority of PNNL’s ASHRAE Standard 90.1 support focuses on developing and evaluating new requirements, a portion of its work involves consideration of the format of energy standards. In its current working plan, the ASHRAE 90.1 committee has approved an energy goal of 50% improvement in Standard 90.1-2013 relative to Standard 90.1-2004, and will likely be considering higher improvement targets for future versions of the standard. To cost-effectively achieve the 50% goal in manner that can gain stakeholder consensus, formats other than prescriptive must be considered. Alternative formats that include reducing the reliance on prescriptive requirements may make it easier to achieve these aggressive efficiency levels in new codes and standards. The focus on energy code and standard formats is meant to explore approaches to presenting the criteria that will foster compliance, enhance verification, and stimulate innovation while saving energy in buildings. New formats may also make it easier for building designers and owners to design and build the levels of efficiency called for in the new codes and standards. This paper examines a number of potential formats and structures, including prescriptive, performance-based (with sub-formats of performance equivalency and performance targets), capacity constraint-based, and outcome-based. The paper also discusses the pros and cons of each format from the viewpoint of code users and of code enforcers.

  9. 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.

  10. Achieving high energy absorption capacity in cellular bulk metallic glasses

    PubMed Central

    Chen, S. H.; Chan, K. C.; Wu, F. F.; Xia, L.

    2015-01-01

    Cellular bulk metallic glasses (BMGs) have exhibited excellent energy-absorption performance by inheriting superior strength from the parent BMGs. However, how to achieve high energy absorption capacity in cellular BMGs is vital but mysterious. In this work, using step-by-step observations of the deformation evolution of a series of cellular BMGs, the underlying mechanisms for the remarkable energy absorption capacity have been investigated by studying two influencing key factors: the peak stress and the decay of the peak stress during the plastic-flow plateau stages. An analytical model of the peak stress has been proposed, and the predicted results agree well with the experimental data. The decay of the peak stress has been attributed to the geometry change of the macroscopic cells, the formation of shear bands in the middle of the struts, and the “work-softening” nature of BMGs. The influencing factors such as the effect of the strut thickness and the number of unit cells have also been investigated and discussed. Strategies for achieving higher energy absorption capacity in cellular BMGs have been proposed. PMID:25973781

  11. Achieving High Resolution Timer Events in Virtualized Environment

    PubMed Central

    Adamczyk, Blazej; Chydzinski, Andrzej

    2015-01-01

    Virtual Machine Monitors (VMM) have become popular in different application areas. Some applications may require to generate the timer events with high resolution and precision. This however may be challenging due to the complexity of VMMs. In this paper we focus on the timer functionality provided by five different VMMs—Xen, KVM, Qemu, VirtualBox and VMWare. Firstly, we evaluate resolutions and precisions of their timer events. Apparently, provided resolutions and precisions are far too low for some applications (e.g. networking applications with the quality of service). Then, using Xen virtualization we demonstrate the improved timer design that greatly enhances both the resolution and precision of achieved timer events. PMID:26177366

  12. Achievement of high nitrite accumulation via endogenous partial denitrification (EPD).

    PubMed

    Ji, Jiantao; Peng, Yongzhen; Wang, Bo; Wang, Shuying

    2017-01-01

    This study proposed a novel strategy for achievement of partial denitrification driven by endogenous carbon sources in an anaerobic/anoxic/aerobic activated sludge system. Results showed that in the steady-stage, the nitrate-to-nitrite transformation ratio (NTR) was kept at around 87% without nitrate in the effluent. During the anaerobic period, exogenous carbon sources was completely taken up, accompanied by the consumption of glycogen and production of polyhydroxyalkanoates (PHAs). During the anoxic period, nitrate was reduced to nitrite by using PHAs as carbon sources, followed by the replenishment of glycogen. Thus, the phenotype of denitrifying GAOs was clearly observed and endogenous partial denitrification (EPD) occurred. Furthermore, results showed the nitrate reduction was prior to the nitrite reduction in the presence of nitrate, which led to the high nitrite accumulation.

  13. Achieving ultra-high temperatures with a resistive emitter array

    NASA Astrophysics Data System (ADS)

    Danielson, Tom; Franks, Greg; Holmes, Nicholas; LaVeigne, Joe; Matis, Greg; McHugh, Steve; Norton, Dennis; Vengel, Tony; Lannon, John; Goodwin, Scott

    2016-05-01

    The rapid development of very-large format infrared detector arrays has challenged the IR scene projector community to also develop larger-format infrared emitter arrays to support the testing of systems incorporating these detectors. In addition to larger formats, many scene projector users require much higher simulated temperatures than can be generated with current technology in order to fully evaluate the performance of their systems and associated processing algorithms. Under the Ultra High Temperature (UHT) development program, Santa Barbara Infrared Inc. (SBIR) is developing a new infrared scene projector architecture capable of producing both very large format (>1024 x 1024) resistive emitter arrays and improved emitter pixel technology capable of simulating very high apparent temperatures. During earlier phases of the program, SBIR demonstrated materials with MWIR apparent temperatures in excess of 1400 K. New emitter materials have subsequently been selected to produce pixels that achieve even higher apparent temperatures. Test results from pixels fabricated using the new material set will be presented and discussed. A 'scalable' Read In Integrated Circuit (RIIC) is also being developed under the same UHT program to drive the high temperature pixels. This RIIC will utilize through-silicon via (TSV) and Quilt Packaging (QP) technologies to allow seamless tiling of multiple chips to fabricate very large arrays, and thus overcome the yield limitations inherent in large-scale integrated circuits. Results of design verification testing of the completed RIIC will be presented and discussed.

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. 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

  20. 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

  1. 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.

  2. All-polymer bulk heterojuction solar cells with 4.8% efficiency achieved by solution processing from a co-solvent.

    PubMed

    Earmme, Taeshik; Hwang, Ye-Jin; Subramaniyan, Selvam; Jenekhe, Samson A

    2014-09-17

    All-polymer solar cells with 4.8% power conversion efficiency are achieved via solution processing from a co-solvent. The observed short-circuit current density of 10.5 mA cm(-2) and external quantum efficiency of 61.3% are also the best reported in all-polymer solar cells so far. The results demonstrate that processing the active layer from a co-solvent is an important strategy in achieving highly efficient all-polymer solar cells.

  3. 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.

  4. 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

  5. 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.

  6. 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.

  7. 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%.

  8. 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.

  9. 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.

  10. How to achieve high-level expression of microbial enzymes

    PubMed Central

    Liu, Long; Yang, Haiquan; Shin, Hyun-dong; Chen, Rachel R.; Li, Jianghua; Du, Guocheng; Chen, Jian

    2013-01-01

    Microbial enzymes have been used in a large number of fields, such as chemical, agricultural and biopharmaceutical industries. The enzyme production rate and yield are the main factors to consider when choosing the appropriate expression system for the production of recombinant proteins. Recombinant enzymes have been expressed in bacteria (e.g., Escherichia coli, Bacillus and lactic acid bacteria), filamentous fungi (e.g., Aspergillus) and yeasts (e.g., Pichia pastoris). The favorable and very advantageous characteristics of these species have resulted in an increasing number of biotechnological applications. Bacterial hosts (e.g., E. coli) can be used to quickly and easily overexpress recombinant enzymes; however, bacterial systems cannot express very large proteins and proteins that require post-translational modifications. The main bacterial expression hosts, with the exception of lactic acid bacteria and filamentous fungi, can produce several toxins which are not compatible with the expression of recombinant enzymes in food and drugs. However, due to the multiplicity of the physiological impacts arising from high-level expression of genes encoding the enzymes and expression hosts, the goal of overproduction can hardly be achieved, and therefore, the yield of recombinant enzymes is limited. In this review, the recent strategies used for the high-level expression of microbial enzymes in the hosts mentioned above are summarized and the prospects are also discussed. We hope this review will contribute to the development of the enzyme-related research field. PMID:23686280

  11. Co-emergence of multi-scale cortical activities of irregular firing, oscillations and avalanches achieves cost-efficient information capacity.

    PubMed

    Yang, Dong-Ping; Zhou, Hai-Jun; Zhou, Changsong

    2017-02-01

    The brain is highly energy consuming, therefore is under strong selective pressure to achieve cost-efficiency in both cortical connectivities and activities. However, cost-efficiency as a design principle for cortical activities has been rarely studied. Especially it is not clear how cost-efficiency is related to ubiquitously observed multi-scale properties: irregular firing, oscillations and neuronal avalanches. Here we demonstrate that these prominent properties can be simultaneously observed in a generic, biologically plausible neural circuit model that captures excitation-inhibition balance and realistic dynamics of synaptic conductance. Their co-emergence achieves minimal energy cost as well as maximal energy efficiency on information capacity, when neuronal firing are coordinated and shaped by moderate synchrony to reduce otherwise redundant spikes, and the dynamical clusterings are maintained in the form of neuronal avalanches. Such cost-efficient neural dynamics can be employed as a foundation for further efficient information processing under energy constraint.

  12. Co-emergence of multi-scale cortical activities of irregular firing, oscillations and avalanches achieves cost-efficient information capacity

    PubMed Central

    Zhou, Hai-Jun; Zhou, Changsong

    2017-01-01

    The brain is highly energy consuming, therefore is under strong selective pressure to achieve cost-efficiency in both cortical connectivities and activities. However, cost-efficiency as a design principle for cortical activities has been rarely studied. Especially it is not clear how cost-efficiency is related to ubiquitously observed multi-scale properties: irregular firing, oscillations and neuronal avalanches. Here we demonstrate that these prominent properties can be simultaneously observed in a generic, biologically plausible neural circuit model that captures excitation-inhibition balance and realistic dynamics of synaptic conductance. Their co-emergence achieves minimal energy cost as well as maximal energy efficiency on information capacity, when neuronal firing are coordinated and shaped by moderate synchrony to reduce otherwise redundant spikes, and the dynamical clusterings are maintained in the form of neuronal avalanches. Such cost-efficient neural dynamics can be employed as a foundation for further efficient information processing under energy constraint. PMID:28192429

  13. 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.

  14. 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.

  15. 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.

  16. Effects of Partner's Ability on the Achievement and Conceptual Organization of High-Achieving Fifth-Grade Students.

    ERIC Educational Resources Information Center

    Carter, Glenda; Jones, M. Gail; Rua, Melissa

    2003-01-01

    Investigates high-achieving fifth-grade students' achievement gains and conceptual reorganization on convection. Features an instructional sequence of three dyadic inquiry investigations related to convection currents as well as pre- and post-assessment consisting of a multiple-choice test, a card sorting task, construction of a concept map, and…

  17. Comparison of the Level of Using Metacognitive Strategies during Study between High Achieving and Low Achieving Prospective Teachers

    ERIC Educational Resources Information Center

    Doganay, Ahmet; Demir, Ozden

    2011-01-01

    The main purpose of this study is to compare the level of using metacognitive strategies during study between high achieving and low achieving prospective classroom teachers. This study was designed as a mixed method study. Metacognitive Learning Strategies Scale developed by Namlu (2004) was used to measure the use of metacognitive strategies…

  18. Achieving high strength and high ductility in magnesium alloy using hard-plate rolling (HPR) process

    PubMed Central

    Wang, Hui–Yuan; Yu, Zhao–Peng; Zhang, Lei; Liu, Chun–Guo; Zha, Min; Wang, Cheng; Jiang, Qi–Chuan

    2015-01-01

    Magnesium alloys are highly desirable for a wide range of lightweight structural components. However, rolling Mg alloys can be difficult due to their poor plasticity, and the strong texture yielded from rolling often results in poor plate forming ability, which limits their further engineering applications. Here we report a new hard-plate rolling (HPR) route which achieves a large reduction during a single rolling pass. The Mg-9Al-1Zn (AZ91) plates processed by HPR consist of coarse grains of 30–60 μm, exhibiting a typical basal texture, fine grains of 1–5 μm and ultrafine (sub) grains of 200–500 nm, both of the latter two having a weakened texture. More importantly, the HPR was efficient in gaining a simultaneous high strength and uniform ductility, i.e., ~371 MPa and ~23%, respectively. The superior properties should be mainly attributed to the cooperation effect of the multimodal grain structure and weakened texture, where the former facilitates a strong work hardening while the latter promotes the basal slip. The HPR methodology is facile and effective, and can avoid plate cracking that is prone to occur during conventional rolling processes. This strategy is applicable to hard-to-deform materials like Mg alloys, and thus has a promising prospect for industrial application. PMID:26603776

  19. Achieving high strength and high ductility in magnesium alloy using hard-plate rolling (HPR) process

    NASA Astrophysics Data System (ADS)

    Wang, Hui–Yuan; Yu, Zhao–Peng; Zhang, Lei; Liu, Chun–Guo; Zha, Min; Wang, Cheng; Jiang, Qi–Chuan

    2015-11-01

    Magnesium alloys are highly desirable for a wide range of lightweight structural components. However, rolling Mg alloys can be difficult due to their poor plasticity, and the strong texture yielded from rolling often results in poor plate forming ability, which limits their further engineering applications. Here we report a new hard-plate rolling (HPR) route which achieves a large reduction during a single rolling pass. The Mg-9Al-1Zn (AZ91) plates processed by HPR consist of coarse grains of 30-60 μm, exhibiting a typical basal texture, fine grains of 1-5 μm and ultrafine (sub) grains of 200-500 nm, both of the latter two having a weakened texture. More importantly, the HPR was efficient in gaining a simultaneous high strength and uniform ductility, i.e., ~371 MPa and ~23%, respectively. The superior properties should be mainly attributed to the cooperation effect of the multimodal grain structure and weakened texture, where the former facilitates a strong work hardening while the latter promotes the basal slip. The HPR methodology is facile and effective, and can avoid plate cracking that is prone to occur during conventional rolling processes. This strategy is applicable to hard-to-deform materials like Mg alloys, and thus has a promising prospect for industrial application.

  20. Achieving high strength and high ductility in magnesium alloy using hard-plate rolling (HPR) process.

    PubMed

    Wang, Hui-Yuan; Yu, Zhao-Peng; Zhang, Lei; Liu, Chun-Guo; Zha, Min; Wang, Cheng; Jiang, Qi-Chuan

    2015-11-25

    Magnesium alloys are highly desirable for a wide range of lightweight structural components. However, rolling Mg alloys can be difficult due to their poor plasticity, and the strong texture yielded from rolling often results in poor plate forming ability, which limits their further engineering applications. Here we report a new hard-plate rolling (HPR) route which achieves a large reduction during a single rolling pass. The Mg-9Al-1Zn (AZ91) plates processed by HPR consist of coarse grains of 30-60 μm, exhibiting a typical basal texture, fine grains of 1-5 μm and ultrafine (sub) grains of 200-500 nm, both of the latter two having a weakened texture. More importantly, the HPR was efficient in gaining a simultaneous high strength and uniform ductility, i.e., ~371 MPa and ~23%, respectively. The superior properties should be mainly attributed to the cooperation effect of the multimodal grain structure and weakened texture, where the former facilitates a strong work hardening while the latter promotes the basal slip. The HPR methodology is facile and effective, and can avoid plate cracking that is prone to occur during conventional rolling processes. This strategy is applicable to hard-to-deform materials like Mg alloys, and thus has a promising prospect for industrial application.

  1. Advanced liquid cooling in HCPVT systems to achieve higher energy efficiencies

    NASA Astrophysics Data System (ADS)

    Zimmermann, S.; Helmers, H.; Tiwari, M. K.; Escher, W.; Paredes, S.; Neves, P.; Poulikakos, D.; Wiesenfarth, M.; Bett, A. W.; Michel, B.

    2013-09-01

    The benefits of advanced thermal packaging are demonstrated through a receiver package consisting of a monolithic interconnected module (MIM) which is directly attached to a high performance microchannel heat sink. Those packages can be applied in high-concentration photovoltaic systems and the generated heat can be used in addition to the electrical power output (CPVT systems). Thus, the total energy efficiency of the system increases significantly. A detailed exergy analysis of the receiver power output underscores the advantages of the new cooling approach.

  2. Maximum achievable efficiency in near-field coupled power-transfer systems.

    PubMed

    Zargham, Meysam; Gulak, P Glenn

    2012-06-01

    Wireless power transfer is commonly realized by means of near-field inductive coupling and is critical to many existing and emerging applications in biomedical engineering. This paper presents a closed form analytical solution for the optimum load that achieves the maximum possible power efficiency under arbitrary input impedance conditions based on the general two-port parameters of the network. The two-port approach allows one to predict the power transfer efficiency at any frequency, any type of coil geometry and through any type of media surrounding the coils. Moreover, the results are applicable to any form of passive power transfer such as provided by inductive or capacitive coupling. Our results generalize several well-known special cases. The formulation allows the design of an optimized wireless power transfer link through biological media using readily available EM simulation software. The proposed method effectively decouples the design of the inductive coupling two-port from the problem of loading and power amplifier design. Several case studies are provided for typical applications.

  3. 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.

  4. 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.

  5. Benefits of Hybrid-Electric Propulsion to Achieve 4x Increase in Cruise Efficiency for a VTOL Aircraft

    NASA Technical Reports Server (NTRS)

    Fredericks, William J.; Moore, Mark D.; Busan, Ronald C.

    2013-01-01

    Electric propulsion enables radical new vehicle concepts, particularly for Vertical Takeoff and Landing (VTOL) aircraft because of their significant mismatch between takeoff and cruise power conditions. However, electric propulsion does not merely provide the ability to normalize the power required across the phases of flight, in the way that automobiles also use hybrid electric technologies. The ability to distribute the thrust across the airframe, without mechanical complexity and with a scale-free propulsion system, is a new degree of freedom for aircraft designers. Electric propulsion is scale-free in terms of being able to achieve highly similar levels of motor power to weight and efficiency across a dramatic scaling range. Applying these combined principles of electric propulsion across a VTOL aircraft permits an improvement in aerodynamic efficiency that is approximately four times the state of the art of conventional helicopter configurations. Helicopters typically achieve a lift to drag ratio (L/D) of between 4 and 5, while the VTOL aircraft designed and developed in this research were designed to achieve an L/D of approximately 20. Fundamentally, the ability to eliminate the problem of advancing and retreating rotor blades is shown, without resorting to unacceptable prior solutions such as tail-sitters. This combination of concept and technology also enables a four times increase in range and endurance while maintaining the full VTOL and hover capability provided by a helicopter. Also important is the ability to achieve low disc-loading for low ground impingement velocities, low noise and hover power minimization (thus reducing energy consumption in VTOL phases). This combination of low noise and electric propulsion (i.e. zero emissions) will produce a much more community-friendly class of vehicles. This research provides a review of the concept brainstorming, configuration aerodynamic and mission analysis, as well as subscale prototype construction and

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. Achieving High Throughput for Data Transfer over ATM Networks

    NASA Technical Reports Server (NTRS)

    Johnson, Marjory J.; Townsend, Jeffrey N.

    1996-01-01

    File-transfer rates for ftp are often reported to be relatively slow, compared to the raw bandwidth available in emerging gigabit networks. While a major bottleneck is disk I/O, protocol issues impact performance as well. Ftp was developed and optimized for use over the TCP/IP protocol stack of the Internet. However, TCP has been shown to run inefficiently over ATM. In an effort to maximize network throughput, data-transfer protocols can be developed to run over UDP or directly over IP, rather than over TCP. If error-free transmission is required, techniques for achieving reliable transmission can be included as part of the transfer protocol. However, selected image-processing applications can tolerate a low level of errors in images that are transmitted over a network. In this paper we report on experimental work to develop a high-throughput protocol for unreliable data transfer over ATM networks. We attempt to maximize throughput by keeping the communications pipe full, but still keep packet loss under five percent. We use the Bay Area Gigabit Network Testbed as our experimental platform.

  12. Does Recreational Computer Use Affect High School Achievement?

    ERIC Educational Resources Information Center

    Bowers, Alex J.; Berland, Matthew

    2013-01-01

    Historically, the relationship between student academic achievement and use of computers for fun and video gaming has been described from a multitude of perspectives, from positive, to negative, to neutral. However, recent research has indicated that computer use and video gaming may be positively associated with achievement, yet these studies…

  13. Student Perception of Academic Achievement Factors at High School

    ERIC Educational Resources Information Center

    Bahar, Mustafa

    2016-01-01

    Measuring the quality of the "product" is elemental in education, and most studies depend on observational data about student achievement factors, focusing overwhelmingly on quantitative data namely achievement scores, school data like attendance, facilities, expenditure class size, etc. But there is little evidence of learner…

  14. High-Achieving High School Students and Not so High-Achieving College Students: A Look at Lack of Self-Control, Academic Ability, and Performance in College

    ERIC Educational Resources Information Center

    Honken, Nora B.; Ralston, Patricia A. S.

    2013-01-01

    This study investigated the relationship among lack of self-control, academic ability, and academic performance for a cohort of freshman engineering students who were, with a few exceptions, extremely high achievers in high school. Structural equation modeling analysis led to the conclusion that lack of self-control in high school, as measured by…

  15. 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%.

  16. 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.

  17. 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.

  18. 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

  19. 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.

  20. 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.

  1. 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

  2. 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.

  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. Threatened and Placed at Risk: High Achieving African American Males in Urban High Schools

    ERIC Educational Resources Information Center

    McGee, Ebony O.

    2013-01-01

    This study investigated the risk and protective factors of 11 high-achieving African American males attending 4 urban charter high schools in a Midwestern city to determine what factors account for their resilience and success in mathematics courses, and in high school more generally. This research was guided by a Phenomenological Variant of…

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. Fabrication of large-aperture, high efficiency, Fresnel diffractive membrane optic for space telescope

    NASA Astrophysics Data System (ADS)

    Zhang, Jian; Li, Mengjuan; Yin, Ganghua; Jiao, Jianchao; Liu, Zhengkun; Xu, Xiangdong; Fu, Shaojun

    2016-10-01

    Diffractive optical system can be a favorable choice for large-aperture space telescope to reduce the mass and size of image system. To meet the demand of large-aperture, high efficiency, lightweight diffractive optic for high resolution remote sensing, a 200 mm diameter, 20 μmthick, 4-level diffractive membrane fabricated is shown to have over 62% diffraction efficiency into the +1 order, with 0.051 efficiency RMS. Over 66% diffraction efficiency is achieved for a 100 mm aperture membrane, with 0.023 efficiency RMS. The membrane thickness uniformity control is discussed and 8 nm wave front error RMS is achieved in 100 mm diameter.

  11. 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.

  12. The Effect of Music Participation on Mathematical Achievement and Overall Academic Achievement of High School Students

    ERIC Educational Resources Information Center

    Cox, H. A.; Stephens, L. J.

    2006-01-01

    A study was conducted on high school students, comparing those with some music credits to those with none. No statistically significant difference was found in their mean math grade point averages (GPA) or their mean cumulative GPAs. Students were then separated into two groups based on the number of music credits. Students who had earned at least…

  13. A locally-blazed ant trail achieves efficient collective navigation despite limited information

    PubMed Central

    Fonio, Ehud; Heyman, Yael; Boczkowski, Lucas; Gelblum, Aviram; Kosowski, Adrian; Korman, Amos; Feinerman, Ofer

    2016-01-01

    Any organism faces sensory and cognitive limitations which may result in maladaptive decisions. Such limitations are prominent in the context of groups where the relevant information at the individual level may not coincide with collective requirements. Here, we study the navigational decisions exhibited by Paratrechina longicornis ants as they cooperatively transport a large food item. These decisions hinge on the perception of individuals which often restricts them from providing the group with reliable directional information. We find that, to achieve efficient navigation despite partial and even misleading information, these ants employ a locally-blazed trail. This trail significantly deviates from the classical notion of an ant trail: First, instead of systematically marking the full path, ants mark short segments originating at the load. Second, the carrying team constantly loses the guiding trail. We experimentally and theoretically show that the locally-blazed trail optimally and robustly exploits useful knowledge while avoiding the pitfalls of misleading information. DOI: http://dx.doi.org/10.7554/eLife.20185.001 PMID:27815944

  14. Spectrally beam combined fiber lasers for high power, efficiency, and brightness

    NASA Astrophysics Data System (ADS)

    Honea, Eric; Afzal, Robert S.; Savage-Leuchs, Matthias; Gitkind, Neil; Humphreys, Richard; Henrie, Jason; Brar, Khush; Jander, Don

    2013-03-01

    Spectral Beam Combining (SBC) of fiber lasers provides a simple, robust architecture for power scaling lasers to high power. With appropriate designs, power scaling beyond the single fiber limit can be achieved while maintaining near diffraction limited beam quality and high efficiency. We present experimental results where we achieved > 3 kW at an M2 = 1.35 and > 39% E-O efficiency by combining 12 individual fiber lasers into a single high brightness beam.

  15. 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.

  16. 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.

  17. Achieving high performance polymer tandem solar cells via novel materials design

    NASA Astrophysics Data System (ADS)

    Dou, Letian

    Organic photovoltaic (OPV) devices show great promise in low-cost, flexible, lightweight, and large-area energy-generation applications. Nonetheless, most of the materials designed today always suffer from the inherent disadvantage of not having a broad absorption range, and relatively low mobility, which limit the utilization of the full solar spectrum. Tandem solar cells provide an effective way to harvest a broader spectrum of solar radiation by combining two or more solar cells with different absorption bands. However, for polymer solar cells, the performance of tandem devices lags behind single-layer solar cells mainly due to the lack of suitable low-bandgap polymers (near-IR absorbing polymers). In this dissertation, in order to achieve high performance, we focus on design and synthesis of novel low bandgap polymers specifically for tandem solar cells. In Chapter 3, I demonstrate highly efficient single junction and tandem polymer solar cells featuring a spectrally matched low-bandgap conjugated polymer (PBDTT-DPP: bandgap, ˜1.44 eV). The polymer has a backbone based on alternating benzodithiophene and diketopyrrolopyrrole units. A single-layer device based on the polymer provides a power conversion efficiency of ˜6%. When the polymer is applied to tandem solar cells, a power conversion efficiency of 8.62% is achieved, which was the highest certified efficiency for a polymer solar cell. To further improve this material system, in Chapter 4, I show that the reduction of the bandgap and the enhancement of the charge transport properties of the low bandgap polymer PBDTT-DPP can be accomplished simultaneously by substituting the sulfur atoms on the DPP unit with selenium atoms. The newly designed polymer PBDTT-SeDPP (Eg = 1.38 eV) shows excellent photovoltaic performance in single junction devices with PCEs over 7% and photo-response up to 900 nm. Tandem polymer solar cells based on PBDTT-SeDPP are also demonstrated with a 9.5% PCE, which are more than 10

  18. 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.

  19. 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

  20. 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.

  1. 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%.

  2. 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.

  3. 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.

  4. Academic attainment and the high school science experiences among high-achieving African American males

    NASA Astrophysics Data System (ADS)

    Trice, Rodney Nathaniel

    This study examines the educational experiences of high achieving African American males. More specifically, it analyzes the influences on their successful navigation through high school science. Through a series of interviews, observations, questionnaires, science portfolios, and review of existing data the researcher attempted to obtain a deeper understanding of high achieving African American males and their limitations to academic attainment and high school science experiences. The investigation is limited to ten high achieving African American male science students at Woodcrest High School. Woodcrest is situated at the cross section of a suburban and rural community located in the southeastern section of the United States. Although this investigation involves African American males, all of whom are successful in school, its findings should not be generalized to this nor any other group of students. The research question that guided this study is: What are the limitations to academic attainment and the high school science experiences of high achieving African American males? The student participants expose how suspension and expulsion, special education placement, academic tracking, science instruction, and teacher expectation influence academic achievement. The role parents play, student self-concept, peer relationships, and student learning styles are also analyzed. The anthology of data rendered three overarching themes: (1) unequal access to education, (2) maintenance of unfair educational structures, and (3) authentic characterizations of African American males. Often the policies and practices set in place by school officials aid in creating hurdles to academic achievement. These policies and practices are often formed without meaningful consideration of the unintended consequences that may affect different student populations, particularly the most vulnerable. The findings from this study expose that high achieving African American males face major

  5. 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.

  6. 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

  7. Development of high-efficiency Stirling cryocoolers for high temperature superconducting motors

    NASA Astrophysics Data System (ADS)

    Nakano, K.; Yumoto, K.; Hiratsuka, Y.

    2015-12-01

    For wide spread high-temperature superconductor (HTS) devices, a cryocooler having COP of >0.1, with a compact size, light weight, high efficiency and high reliability is required. For practical use of superconductive devices, Sumitomo Heavy Industries, Ltd. (SHI) developed a high-efficiency Stirling type pulse tube cryocooler (STPC). The STPC had high reliability and low vibration. However, its efficiency was not enough to meet the demands of an HTS motor. To further improve the efficiency, we reconsidered the expander of cryocooler and developed a Stirling cryocooler (STC). Two prototype units of a compact, high-efficiency split Stirling cryocooler were designed, built and tested. With the second prototype unit, a cooling capacity of 151 W at 70 K and a minimum temperature of 33 K have been achieved with a compressor input power of 2.15 kW. Accordingly, COP of about 0.07 has been achieved. The detailed design of the prototype units and the experimental results will be reported in this paper.

  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. 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).

  10. Dominant Achievement Goals across Tracks in High School

    ERIC Educational Resources Information Center

    Scheltinga, Peter A. M.; Kuyper, Hans; Timmermans, Anneke C.; van der Werf, Greetje P. C.

    2016-01-01

    The dominant achievement goals (DAGs) of 7,008 students in the third grade of Dutch secondary education (US grade 9) were investigated, based on Elliot & McGregors' 2 × 2 framework (2001), in relation to track-level and motivational variables. We found the mastery-approach goal and the performance-approach goal, generally considered adaptive,…

  11. Charter High Schools: Closing the Achievement Gap. Innovations in Education

    ERIC Educational Resources Information Center

    US Department of Education, 2006

    2006-01-01

    The eight schools profiled in this document are serving different populations, but all of them are closing the achievement gap between low-income, minority, and special needs students and their peers. By trying out innovative new strategies, these schools are blazing a trail for others to follow. They are dispelling the myth that some students can…

  12. "Brains before "Beauty"?" High Achieving Girls, School and Gender Identities

    ERIC Educational Resources Information Center

    Skelton, Christine; Francis, Becky; Read, Barbara

    2010-01-01

    In recent years educational policy on gender and achievement has concentrated on boys' underachievement, frequently comparing it with the academic success of girls. This has encouraged a perception of girls as the "winners" of the educational stakes and assumes that they no longer experience the kinds of gender inequalities identified in…

  13. 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.

  14. Parenting Style, Perfectionism, and Creativity in High-Ability and High-Achieving Young Adults

    ERIC Educational Resources Information Center

    Miller, Angie L.; Lambert, Amber D.; Speirs Neumeister, Kristie L.

    2012-01-01

    The current study explores the potential relationships among perceived parenting style, perfectionism, and creativity in a high-ability and high-achieving young adult population. Using data from 323 honors college students at a Midwestern university, bivariate correlations suggested positive relationships between (a) permissive parenting style and…

  15. Success Despite Socioeconomics: A Case Study of a High-Achieving, High-Poverty School

    ERIC Educational Resources Information Center

    Tilley, Thomas Brent; Smith, Samuel J.; Claxton, Russell L.

    2012-01-01

    This case study of a high-achieving, high-poverty school describes the school's leadership, culture, and programs that contributed to its success. Data were collected from two surveys (the School Culture Survey and the Vanderbilt Assessment of Leadership in Education), observations at the school site, and interviews with school personnel. The…

  16. 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

  17. 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.

  18. Mathematical and numerical models to achieve high speed with special-purpose parallel processors

    SciTech Connect

    Cheng, H.S.; Wulff, W.; Mallen, A.N.

    1986-07-01

    One simulation facility that has been developed is the BNL Plant Analyzer, currently set up for BWR plant simulations at up to seven times faster than real-time process speeds. The principal hardware components of the BNL Plant Analyzer are two units of special-purpose parallel processors, the AD10 of Applied Dynamics International and a PDP-11/34 host computer. The AD10 is specifically designed for time-critical system simulations, utilizing the modern parallel processing technology with pipeline architecture. The simulator employs advanced modeling techniques and efficient integration techniques in conjunction with the parallel processors to achieve high speed performance.

  19. 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.

  20. Development of a High Efficiency Thermoelectric Unicouple for Power Generation Applications

    NASA Technical Reports Server (NTRS)

    Caillat, T.; Fleurial, J-P.; Synder, G.; Zoltan, A.; Zoltan, D.; Borshchevsky, A.

    1999-01-01

    To achieve high thermal-to-electric energy conversion efficiency, it is desirable to operate thermoelectric generator devices over large temperature gradients and also to maximize the performance of the thermoelectric materials used to build the devices.

  1. 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.

  2. 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.

  3. Development of manufacturing capability for high-concentration, high-efficiency silicon solar cells

    SciTech Connect

    Sinton, R.A.; Verlinden, P.J.; Crane, R.A.; Swanson, R.N.

    1996-10-01

    This report presents a summary of the major results from a program to develop a manufacturable, high-efficiency silicon concentrator solar cell and a cost-effective manufacturing facility. The program was jointly funded by the Electric Power Research Institute, Sandia National Laboratories through the Concentrator Initiative, and SunPower Corporation. The key achievements of the program include the demonstration of 26%-efficient silicon concentrator solar cells with design-point (20 W/cm{sup 2}) efficiencies over 25%. High-performance front-surface passivations; that were developed to achieve this result were verified to be absolutely stable against degradation by 475 days of field exposure at twice the design concentration. SunPower demonstrated pilot production of more than 1500 of these cells. This cell technology was also applied to pilot production to supply 7000 17.7-cm{sup 2} one-sun cells (3500 yielded wafers) that demonstrated exceptional quality control. The average efficiency of 21.3% for these cells approaches the peak efficiency ever demonstrated for a single small laboratory cell within 2% (absolute). Extensive cost models were developed through this program and calibrated by the pilot-production project. The production levels achieved indicate that SunPower could produce 7-10 MW of concentrator cells per year in the current facility based upon the cell performance demonstrated during the program.

  4. Achieving High Performance in AC-Field Driven Organic Light Sources

    PubMed Central

    Xu, Junwei; Carroll, David L.; Smith, Gregory M.; Dun, Chaochao; Cui, Yue

    2016-01-01

    Charge balance in organic light emitting structures is essential to simultaneously achieving high brightness and high efficiency. In DC-driven organic light emitting devices (OLEDs), this is relatively straight forward. However, in the newly emerging, capacitive, field-activated AC-driven organic devices, charge balance can be a challenge. In this work we introduce the concept of gating the compensation charge in AC-driven organic devices and demonstrate that this can result in exceptional increases in device performance. To do this we replace the insulator layer in a typical field-activated organic light emitting device with a nanostructured, wide band gap semiconductor layer. This layer acts as a gate between the emitter layer and the voltage contact. Time resolved device characterization shows that, at high-frequencies (over 40 kHz), the semiconductor layer allows for charge accumulation in the forward bias, light generating part of the AC cycle and charge compensation in the negative, quiescent part of the AC cycle. Such gated AC organic devices can achieve a non-output coupled luminance of 25,900 cd/m2 with power efficiencies that exceed both the insulator-based AC devices and OLEDs using the same emitters. This work clearly demonstrates that by realizing balanced management of charge, AC-driven organic light emitting devices may well be able to rival today’s OLEDs in performance. PMID:27063414

  5. Achieving High Performance in AC-Field Driven Organic Light Sources

    NASA Astrophysics Data System (ADS)

    Xu, Junwei; Carroll, David L.; Smith, Gregory M.; Dun, Chaochao; Cui, Yue

    2016-04-01

    Charge balance in organic light emitting structures is essential to simultaneously achieving high brightness and high efficiency. In DC-driven organic light emitting devices (OLEDs), this is relatively straight forward. However, in the newly emerging, capacitive, field-activated AC-driven organic devices, charge balance can be a challenge. In this work we introduce the concept of gating the compensation charge in AC-driven organic devices and demonstrate that this can result in exceptional increases in device performance. To do this we replace the insulator layer in a typical field-activated organic light emitting device with a nanostructured, wide band gap semiconductor layer. This layer acts as a gate between the emitter layer and the voltage contact. Time resolved device characterization shows that, at high-frequencies (over 40 kHz), the semiconductor layer allows for charge accumulation in the forward bias, light generating part of the AC cycle and charge compensation in the negative, quiescent part of the AC cycle. Such gated AC organic devices can achieve a non-output coupled luminance of 25,900 cd/m2 with power efficiencies that exceed both the insulator-based AC devices and OLEDs using the same emitters. This work clearly demonstrates that by realizing balanced management of charge, AC-driven organic light emitting devices may well be able to rival today’s OLEDs in performance.

  6. 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.

  7. 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

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. The Relationship between Self-Esteem and Academic Achievement in a Group of High, Medium, and Low Secondary Public High School Achievers.

    ERIC Educational Resources Information Center

    Thomas-Brantley, Betty J.

    This study investigated the relationship between self-esteem and academic achievement in a group of 150 high, medium, and low achievers at a large midwestern public high school. Correlating data from the Coopersmith Inventory of self-esteem with grades, cumulative grade point averages, and class rank, the study disclosed a positive correlation…

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. Optimal design study of high efficiency indium phosphide space solar cells

    NASA Technical Reports Server (NTRS)

    Jain, Raj K.; Flood, Dennis J.

    1990-01-01

    Recently indium phosphide solar cells have achieved beginning of life AMO efficiencies in excess of 19 pct. at 25 C. The high efficiency prospects along with superb radiation tolerance make indium phosphide a leading material for space power requirements. To achieve cost effectiveness, practical cell efficiencies have to be raised to near theoretical limits and thin film indium phosphide cells need to be developed. The optimal design study is described of high efficiency indium phosphide solar cells for space power applications using the PC-1D computer program. It is shown that cells with efficiencies over 22 pct. AMO at 25 C could be fabricated by achieving proper material and process parameters. It is observed that further improvements in cell material and process parameters could lead to experimental cell efficiencies near theoretical limits. The effect of various emitter and base parameters on cell performance was studied.

  19. 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

  20. Incremental Efficiency of WISC-III Factor Scores in Predicting Achievement: What Do They Tell Us?

    ERIC Educational Resources Information Center

    Glutting, Joseph J.; Youngstrom, Eric A.; Ward, Thomas; Ward, Sandra; Hale, Robert L.

    1997-01-01

    The incremental validity of factor scores from the Wechlser Intelligence Scale for Children-III (WISC-III) in predicting scores on the Wechsler Individual Achievement Test (WIAT) was studied in 283 nonreferred children and 636 referred for evaluation. The Full Scale IQ of the WISC-III was the best predictor of WIAT achievement. (SLD)

  1. Relationships among Stress, Coping, and Mental Health in High-Achieving High School Students

    ERIC Educational Resources Information Center

    Suldo, Shannon M.; Shaunessy, Elizabeth; Hardesty, Robin

    2008-01-01

    This study investigates the relationships among stress, coping, and mental health in 139 students participating in an International Baccalaureate (IB) high school diploma program. Mental health was assessed using both positive indicators (life satisfaction, academic achievement, academic self-efficacy) and negative indicators (psychopathology) of…

  2. Examining Organizational Practices That Predict Persistence among High-Achieving Black Males in High School

    ERIC Educational Resources Information Center

    Anderson, Kenneth Alonzo

    2016-01-01

    Background/Context: This article summarizes an increasing trend of antideficit Black male research in mathematics and highlights opportunities to add to the research. A review of the literature shows that antideficit researchers often examine relationships between individual traits and persistence of high-achieving Black males in mathematics.…

  3. The Strengths of High-Achieving Black High School Students in a Racially Diverse Setting

    ERIC Educational Resources Information Center

    Marsh, Kris; Chaney, Cassandra; Jones, Derrick

    2012-01-01

    Robert Hill (1972) identified strengths of Black families: strong kinship bonds, strong work orientation, adaptability of family roles, high achievement orientation, and religious orientation. Some suggest these strengths sustain the physical, emotional, social, and spiritual needs of Blacks. This study used narratives and survey data from a…

  4. 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.

  5. Relationship between High School Mathematical Achievement and Quantitative GPA

    ERIC Educational Resources Information Center

    Brown, Jennifer L.; Halpin, Glennelle; Halpin, Gerald

    2015-01-01

    The demand for STEM graduates has increased, but the number of incoming freshmen who declare a STEM major has remained stagnant. High school courses, such as calculus, can open or close the gate for students interested in careers in STEM. The purpose of this study was to determine if high school mathematics preparation was a significant…

  6. 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

  7. A 12%-efficient upgraded metallurgical grade silicon-organic heterojunction solar cell achieved by a self-purifying process.

    PubMed

    Zhang, Jie; Song, Tao; Shen, Xinlei; Yu, Xuegong; Lee, Shuit-Tong; Sun, Baoquan

    2014-11-25

    Low-quality silicon such as upgraded metallurgical-grade (UMG) silicon promises to reduce the material requirements for high-performance cost-effective photovoltaics. So far, however, UMG silicon currently exhibits the short diffusion length and serious charge recombination associated with high impurity levels, which hinders the performance of solar cells. Here, we used a metal-assisted chemical etching (MACE) method to partially upgrade the UMG silicon surface. The silicon was etched into a nanostructured one by the MACE process, associated with removing impurities on the surface. Meanwhile, nanostructured forms of UMG silicon can benefit improved light harvesting with thin substrates, which can relax the requirement of material purity for high photovoltaic performance. In order to suppress the large surface recombination due to increased surface area of nanostructured UMG silicon, a post chemical treatment was used to decrease the surface area. A solution-processed conjugated polymer of poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) was deposited on UMG silicon at low temperature (<150 °C) to form a heterojunction to avoid any impurity diffusion in the silicon substrate. By optimizing the thickness of silicon and suppressing the charge recombination at the interface between thin UMG silicon/PEDOT:PSS, we are able to achieve 12.0%-efficient organic-inorganic hybrid solar cells, which are higher than analogous UMG silicon devices. We show that the modified UMG silicon surface can increase the minority carrier lifetime because of reduced impurity and surface area. Our results suggest a design rule for an efficient silicon solar cell with low-quality silicon absorbers.

  8. 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.

  9. 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.

  10. Practically Perfect in Every Way: Can Reframing Perfectionism for High-Achieving Undergraduates Impact Academic Resilience?

    ERIC Educational Resources Information Center

    Dickinson, Mary J.; Dickinson, David A. G.

    2015-01-01

    This study focuses on a pan-disciplinary scheme that targeted high-achieving undergraduate students. Earlier research from the scheme argued that high achievers have discernibly different learning and personal development support needs. One of the most frequent self-reported challenges within this high-achieving group is perfectionism. This…

  11. High Achiever: A School Modernization Uncovers Hidden Potential.

    ERIC Educational Resources Information Center

    Babcock, Regina Raiford

    2003-01-01

    Describes the renovation of Lisle Senior High School in Lisle, Illinois, including the educational context and design goals. Includes information on the architects, suppliers, and construction team. Also includes the floor plan and photographs. (EV)

  12. 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

  13. 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

  14. 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.

  15. 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.

  16. 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

  17. Gender, Student Motivation and Academic Achievement in a Midsized Wisconsin High School

    ERIC Educational Resources Information Center

    Lutzke, Steven Ronald

    2013-01-01

    This mixed-methods study investigated relationships among gender, academic motivation and achievement in a mid-sized Wisconsin high school. A questionnaire was developed that focused on perceived ability, achievement motives and achievement goals. Interviews with teachers focused on relationships among academic motivation and gender achievement.…

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. Student Achievement Data Systems in High and Low Performing Schools

    ERIC Educational Resources Information Center

    Stachowiak, Jeannie E.

    2013-01-01

    The purpose of this study was to determine if there was a difference in how high and low performing elementary school districts use and analyze data to differentiate instruction, make changes to district/grade level curriculum, determine professional development needs, determine teacher effectiveness, and determine the use of school district…

  3. Behaviour and achievement disorders in children with high intelligence.

    PubMed

    Barchmann, H; Kinze, W

    1990-01-01

    With 6% of the patients of a childpsychiatric population using treatment a high intelligence with an IQ of over 120 was the result. This is in agreement with the results by Reinhard (1981), but is below the results by Schmidt (1977) and justifies neither the association to a higher talent as risk factor nor as protective factor in view of a potential psychic illness. 341 child-neuropsychiatric patients with hyperkinetic syndrome (55%), Enuresis (28%), reactions of adaptation (5%), specific emotional disturbances in childhood (4%), Encopresis (3%), Psychalgy (3%) and tics (2%) were studied; thereby 22 highly intelligent patients were compared with average intelligent patients. With high intelligence better performances of concentration, more reflexive style of study, better school notes and more favourable motor capabilities, less pronounced signs of anxiety and neuroticism are found, but also a poorer social adaptation and less favourable effects of treatment. Concerning the poorer chances of treatment with high intelligence however the behaviour-therapeutic concentration of our therapy has to be pointed out, which might not offer an optimal chance for development.

  4. Organizational Citizenship of Faculty and Achievement of High School Students

    ERIC Educational Resources Information Center

    DiPaola, Michael F.; Hoy, Wayne K.

    2005-01-01

    All successful organizations, including successful high schools, have employees who go beyond their formal job responsibilities and freely give of their time and energy to succeed. Organ was the first to use the phrase "organizational citizenship behavior" (OCB) to denote organizationally beneficial behavior of workers that was not prescribed but…

  5. Common Core and America's High-Achieving Students

    ERIC Educational Resources Information Center

    Plucker, Jonathan A.

    2015-01-01

    While the merit and politics of the Common Core State Standards (CCSS) have been much debated and discussed, one topic has been virtually ignored: What do the standards portend for America's high-ability students? This brief addresses that question and provides guidance for CCSS-implementing districts and schools as they seek to help these…

  6. Syllabication Skills and Reading Achievement of High School Students.

    ERIC Educational Resources Information Center

    Curry, Robert L.; Geis, Lynna

    A sample of 175 students, constituting grades 10, 11, and 12 of two high schools, was used in the validation of a new Syllabication Skills Test. On the first day, the students completed four forms of the syllabication test; on the second, they completed Survey F of the Gates-MacGinitie Reading Tests. Means and standard deviations were similar for…

  7. Technology's Achilles Heel: Achieving High-Quality Implementation

    ERIC Educational Resources Information Center

    Hall, Gene E.

    2010-01-01

    An inherent characteristic of technology education is the continual development of new technologies and creating innovative applications of already existing technologies. As exciting as these innovations can be, technology educators and school staffs are frequently challenged to accomplish high levels of implementation. The metaphor of the…

  8. Alternative High School Scheduling. Student Achievement and Behavior. Research Report.

    ERIC Educational Resources Information Center

    Pisapia, John; Westfall, Amy Lynn

    In 1995 the Metropolitan Educational Research Consortium (MERC), Richmond (Virginia) commissioned a study of alternative high school scheduling modules to determine the effects of different schedules on teaching strategies, teacher and student satisfaction, and student and school performance. This report presents results of an analysis of student…

  9. High-Achieving Schools Put Equity Front and Center

    ERIC Educational Resources Information Center

    Gleason, Sonia Caus; Gerzon, Nancy

    2014-01-01

    How does professional learning look and feel in high-poverty schools where every student makes at least one year's worth of progress every year? How do schools and leaders put all the varied components of professional learning together so that they support all students learning every day? What professional learning grounds and sustains educators…

  10. More High-Achieving Students Are Choosing Community Colleges First

    ERIC Educational Resources Information Center

    Pluviose, David

    2008-01-01

    Certainly, "Tonight Show" host Jay Leno has nurtured the perception that community colleges are a punishment for underperforming high school students by joking that community colleges aren't "real colleges." This article shows that this perception belies the reality that contemporary community colleges serve students seeking trade skills but also…

  11. Impact of learning orientation on African American children's attitudes toward high-achieving peers.

    PubMed

    Marryshow, Derrick; Hurley, Eric A; Allen, Brenda A; Tyler, Kenneth M; Boykin, A Wade

    2005-01-01

    This study examined Ogbu's widely accepted thesis that African American students reject high academic achievement because they perceive its limited utility in a world where their upward mobility is constrained by racial discrimination. Boykin's psychosocial integrity model contends that Black students value high achievement but that discrepancies between their formative cultural experiences and those imposed in school lead them to reject the modes of achievement available in classrooms. Ninety Black children completed a measure of attitudes toward students who achieve via mainstream or African American cultural values. Participants rejected the mainstream achievers and embraced the African American cultural achievers. Moreover, they expected their teachers to embrace the mainstream achievers and reject those who achieved through high-verve behavior. Results suggest that Boykin's thesis is a needed refinement to Ogbu's ideas. They indicate that Black children may reject not high achievement but some of the mainstream cultural values and behaviors on which success in mainstream classrooms is made contingent.

  12. High-power and highly efficient diode-cladding-pumped Ho3+-doped silica fiber lasers.

    PubMed

    Jackson, Stuart D; Bugge, Frank; Erbert, Götz

    2007-11-15

    We demonstrate high-power operation from a singly Ho3+-doped silica fiber laser that is cladding pumped directly with diode lasers operating at 1150 nm. Internal slope efficiencies approaching the Stokes limit were produced, and the maximum output power was 2.2W. This result was achieved using a low Ho3+-ion concentration and La3+-ion codoping, which together limit the transfer of energy between excited Ho3+ ions.

  13. 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.

  14. 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.

  15. 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.

  16. Achieving High Reliability Operations Through Multi-Program Integration

    SciTech Connect

    Holly M. Ashley; Ronald K. Farris; Robert E. Richards

    2009-04-01

    Over the last 20 years the Idaho National Laboratory (INL) has adopted a number of operations and safety-related programs which has each periodically taken its turn in the limelight. As new programs have come along there has been natural competition for resources, focus and commitment. In the last few years, the INL has made real progress in integrating all these programs and are starting to realize important synergies. Contributing to this integration are both collaborative individuals and an emerging shared vision and goal of the INL fully maturing in its high reliability operations. This goal is so powerful because the concept of high reliability operations (and the resulting organizations) is a masterful amalgam and orchestrator of the best of all the participating programs (i.e. conduct of operations, behavior based safety, human performance, voluntary protection, quality assurance, and integrated safety management). This paper is a brief recounting of the lessons learned, thus far, at the INL in bringing previously competing programs into harmony under the goal (umbrella) of seeking to perform regularly as a high reliability organization. In addition to a brief diagram-illustrated historical review, the authors will share the INL’s primary successes (things already effectively stopped or started) and the gaps yet to be bridged.

  17. 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.

  18. 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.

  19. O&M Best Practices - A Guide to Achieving Operational Efficiency (Release 2.0)

    SciTech Connect

    Sullivan, Gregory P.; Pugh, Ray; Melendez, Aldo P.; Hunt, W. D.

    2004-07-31

    This guide, sponsored by DOE's Federal Energy Management Program, highlights operations and maintenance (O&M) programs targeting energy efficiency that are estimated to save 5% to 20% on energy bills without a significant capital investment. The purpose of this guide is to provide the federal O&M energy manager and practitioner with useful information about O&M management, technologies, energy efficiency and cost-reduction approaches.

  20. From Dropout to High Achiever: An Understanding of Academic Excellence through the Ethnography of High and Low Achieving Secondary School Students.

    ERIC Educational Resources Information Center

    Cuellar, Alfredo

    This paper, a follow-up to a previous review of literature on academic excellence that synthesized information from the United States and Mexico, describes an ethnographic study of high-achieving and low-achieving Hispanic secondary school students from Calexico, California and Mexicali, Baja California Mexico. Five students for each group were…

  1. Proceedings of the Flat-plate Solar Array Project Research Forum on High-efficiency Crystalline Silicon Solar Cells

    NASA Technical Reports Server (NTRS)

    Kachare, R.

    1985-01-01

    The high-efficiency crystalline silicon solar cells research forum addressed high-efficiency concepts, surface-interface effects, bulk effects, modeling and device processing. The topics were arranged into six interactive sessions, which focused on the state-of-the-art of device structures, identification of barriers to achieve high-efficiency cells and potential ways to overcome these barriers.

  2. 975 nm high power diode lasers with high efficiency and narrow vertical far field enabled by low index quantum barriers

    NASA Astrophysics Data System (ADS)

    Crump, P.; Pietrzak, A.; Bugge, F.; Wenzel, H.; Erbert, G.; Tränkle, G.

    2010-03-01

    For optimal coupled power into fiber, high power diode lasers should operate efficiently with smallest possible vertical far field emission angle. Although waveguide and cladding layers can be designed to achieve small angles, the refractive index profile of the active region itself restricts the minimum achievable value. We show that the use of low index quantum barrier layers leads to substantially reduced far field angles, while sustaining high power conversion efficiency. 90 μm stripe lasers that use such designs have narrow vertical far field angles of 30° (95% power content), power conversion efficiency of 58% and operate reliably at 10 W output.

  3. Achieving high data reduction with integral cubic B-splines

    NASA Technical Reports Server (NTRS)

    Chou, Jin J.

    1993-01-01

    During geometry processing, tangent directions at the data points are frequently readily available from the computation process that generates the points. It is desirable to utilize this information to improve the accuracy of curve fitting and to improve data reduction. This paper presents a curve fitting method which utilizes both position and tangent direction data. This method produces G(exp 1) non-rational B-spline curves. From the examples, the method demonstrates very good data reduction rates while maintaining high accuracy in both position and tangent direction.

  4. 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

  5. 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.

  6. 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.

  7. High Achievement in Mathematics Education in India: A Report from Mumbai

    ERIC Educational Resources Information Center

    Raman, Manya

    2010-01-01

    This paper reports a study aimed at characterizing the conditions that lead to high achievement in mathematics in India. The study involved eight schools in the greater Mumbai region. The main result of the study is that the notion of high achievement itself is problematic, as reflected in the reports about mathematics achievement within and…

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

    SciTech Connect

    Gravel, Roland; Maronde, Carl; Gehrke, Chris; Fiveland, Scott

    2010-10-30

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

  9. 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.

  10. Designing and optimizing highly efficient grating for high-brightness laser based on spectral beam combining

    SciTech Connect

    Yang, Ying-Ying E-mail: yangyy@semi.ac.cn; Zhao, Ya-Ping; Wang, Li-Rong; Zhang, Ling; Lin, Xue-Chun E-mail: yangyy@semi.ac.cn

    2015-03-14

    A highly efficient nano-periodical grating is theoretically investigated for spectral beam combining (SBC) and is experimentally implemented for attaining high-brightness laser from a diode laser array. The rigorous coupled-wave analysis with the S matrix method is employed to optimize the parameters of the grating. According the optimized parameters, the grating is fabricated and plays a key role in SBC cavity. The diffraction efficiency of this grating is optimized to 95% for the output laser which is emitted from the diode laser array. The beam parameter product of 3.8 mm mrad of the diode laser array after SBC is achieved at the output power of 46.3 W. The optical-to-optical efficiency of SBC cavity is measured to be 93.5% at the maximum operating current in the experiment.

  11. Designing and optimizing highly efficient grating for high-brightness laser based on spectral beam combining

    NASA Astrophysics Data System (ADS)

    Yang, Ying-Ying; Zhao, Ya-Ping; Wang, Li-Rong; Zhang, Ling; Lin, Xue-Chun

    2015-03-01

    A highly efficient nano-periodical grating is theoretically investigated for spectral beam combining (SBC) and is experimentally implemented for attaining high-brightness laser from a diode laser array. The rigorous coupled-wave analysis with the S matrix method is employed to optimize the parameters of the grating. According the optimized parameters, the grating is fabricated and plays a key role in SBC cavity. The diffraction efficiency of this grating is optimized to 95% for the output laser which is emitted from the diode laser array. The beam parameter product of 3.8 mm mrad of the diode laser array after SBC is achieved at the output power of 46.3 W. The optical-to-optical efficiency of SBC cavity is measured to be 93.5% at the maximum operating current in the experiment.

  12. A Thorough and Efficient Education: School Funding, Student Achievement and Productivity

    ERIC Educational Resources Information Center

    Ahlgrim, Richard W.

    2010-01-01

    Many school districts are facing stagnant or reduced funding (input) concurrent with demands for improved student achievement (output). In other words, there is pressure for all schools, even those schools with student populations of low socioeconomic status, to improve academic results (accountability for output) without a directly proportionate…

  13. Finding Efficiency in the Design of Large Multisite Evaluations: Estimating Variances for Science Achievement Studies

    ERIC Educational Resources Information Center

    Westine, Carl D.

    2016-01-01

    Little is known empirically about intraclass correlations (ICCs) for multisite cluster randomized trial (MSCRT) designs, particularly in science education. In this study, ICCs suitable for science achievement studies using a three-level (students in schools in districts) MSCRT design that block on district are estimated and examined. Estimates of…

  14. 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.

  15. Rectangular Dielectric-loaded Structures for Achieving High Acceleration Gradients

    NASA Astrophysics Data System (ADS)

    Wang, Changbiao; Yakovlev, V. P.; Marshall, T. C.; LaPointe, M. A.; Hirshfield, J. L.

    2006-11-01

    Rectangular dielectric-loaded structures are described that may sustain higher acceleration gradients than conventional all-metal structures with similar apertures. One structure is a test cavity designed to ascertain the breakdown limits of dielectrics, while a second structure could be the basis for a two-beam accelerator. CVD diamond is an attractive dielectric for a high-gradient structure, since the published DC breakdown limit for CVD diamond is ˜ 2 GV/m, although the limit has never been determined for RF fields. Here we present a design of a diamond-lined test cavity to measure the breakdown limit. The designed cavity operates at 34 GHz, where with 10-MW input power it is expected to produce an ˜800 MV/m field on the diamond surface—provided breakdown is avoided. The two channel rectangular dielectric-loaded waveguide could be a two-beam accelerator structure, in which a drive beam is in one channel and an accelerated beam is in the other. The RF power produced by drive bunches in the drive channel is continuously coupled to the acceleration channel. The ratio of fields in the channels (transformer ratio) for the operating mode can be designed by adjusting the dimensions of the structure. An example of the two-channel structure is described, in which a train of five 3-nC drive bunches excites wake fields in the accelerator channel of up to 1.3 GV/m with a transformer ratio of 10 for the design mode.

  16. 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

  17. 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

  18. Black silicon solar cells with interdigitated back-contacts achieve 22.1% efficiency

    NASA Astrophysics Data System (ADS)

    Savin, Hele; Repo, Päivikki; von Gastrow, Guillaume; Ortega, Pablo; Calle, Eric; Garín, Moises; Alcubilla, Ramon

    2015-07-01

    The nanostructuring of silicon surfaces—known as black silicon—is a promising approach to eliminate front-surface reflection in photovoltaic devices without the need for a conventional antireflection coating. This might lead to both an increase in efficiency and a reduction in the manufacturing costs of solar cells. However, all previous attempts to integrate black silicon into solar cells have resulted in cell efficiencies well below 20% due to the increased charge carrier recombination at the nanostructured surface. Here, we show that a conformal alumina film can solve the issue of surface recombination in black silicon solar cells by providing excellent chemical and electrical passivation. We demonstrate that efficiencies above 22% can be reached, even in thick interdigitated back-contacted cells, where carrier transport is very sensitive to front surface passivation. This means that the surface recombination issue has truly been solved and black silicon solar cells have real potential for industrial production. Furthermore, we show that the use of black silicon can result in a 3% increase in daily energy production when compared with a reference cell with the same efficiency, due to its better angular acceptance.

  19. Black silicon solar cells with interdigitated back-contacts achieve 22.1% efficiency.

    PubMed

    Savin, Hele; Repo, Päivikki; von Gastrow, Guillaume; Ortega, Pablo; Calle, Eric; Garín, Moises; Alcubilla, Ramon

    2015-07-01

    The nanostructuring of silicon surfaces--known as black silicon--is a promising approach to eliminate front-surface reflection in photovoltaic devices without the need for a conventional antireflection coating. This might lead to both an increase in efficiency and a reduction in the manufacturing costs of solar cells. However, all previous attempts to integrate black silicon into solar cells have resulted in cell efficiencies well below 20% due to the increased charge carrier recombination at the nanostructured surface. Here, we show that a conformal alumina film can solve the issue of surface recombination in black silicon solar cells by providing excellent chemical and electrical passivation. We demonstrate that efficiencies above 22% can be reached, even in thick interdigitated back-contacted cells, where carrier transport is very sensitive to front surface passivation. This means that the surface recombination issue has truly been solved and black silicon solar cells have real potential for industrial production. Furthermore, we show that the use of black silicon can result in a 3% increase in daily energy production when compared with a reference cell with the same efficiency, due to its better angular acceptance.

  20. Efficiency of Students' Achievement Using Black/White and Color Coded Learning and Test Materials.

    ERIC Educational Resources Information Center

    Lamberski, Richard J.; Roberts, Dennis M.

    The purpose of this study was to compute and analyze descriptive indices of efficiency assessing the relative effectiveness of a verbal and visual color code applied to self-paced learning and testing materials. The sample consisted of 176 college subjects randomly assigned to one of four treatment conditions receiving black/white (B) or color…

  1. 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.

  2. 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.

  3. Analysis of highly-efficient electric residential HPWHs

    SciTech Connect

    Baxter, Van D; Murphy, Richard W; Rice, C Keith; Shen, Bo; Gao, Zhiming

    2011-09-01

    A scoping level analysis was conducted to identify electric HPWH concepts that have the potential to achieve or exceed 30% source energy savings compared to a gas tankless water heater (GTWH) representative of the type represented in version 0.9.5.2 beta of the BEopt software developed by the National Renewable Energy Laboratory. The analysis was limited to evaluation of options to improve the energy efficiency of electric HPWH product designs currently on the market in the US. The report first defines the baseline GTWH system and determines its efficiency (source-energy-based adjusted or derated EF of ~0.71). High efficiency components (compressors, pumps, fans, heat exchangers, etc.) were identified and applied to current US HPWH products and analyzed to determine the viability of reaching the target EF. The target site-based energy factor (EF) required for an electric HPWH necessary to provide 30% source energy savings compared to the GTWH baseline unit is then determined to be ~3.19.

  4. 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.

  5. 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.

  6. Identification of Energy Efficiency Opportunities through Building Data Analysis and Achieving Energy Savings through Improved Controls

    SciTech Connect

    Katipamula, Srinivas; Taasevigen, Danny J.; Koran, Bill

    2014-09-04

    This chapter will highlight analysis techniques to identify energy efficiency opportunities to improve operations and controls. A free tool, Energy Charting and Metrics (ECAM), will be used to assist in the analysis of whole-building, sub-metered, and/or data from the building automation system (BAS). Appendix A describes the features of ECAM in more depth, and also provide instructions for downloading ECAM and all resources pertaining to using ECAM.

  7. Development of compact high efficiency microstructured semiconductor neutron detectors

    NASA Astrophysics Data System (ADS)

    McGregor, D. S.; Bellinger, S. L.; Fronk, R. G.; Henson, L.; Huddleston, D.; Ochs, T.; Shultis, J. K.; Sobering, T. J.; Taylor, R. D.

    2015-11-01

    Semiconductor diode detectors coated with neutron reactive materials are generally fashioned as planar diodes coated with 10B, 6LiF, or Gd. Planar detectors coated with 10B or 6LiF are limited to less than 5% intrinsic thermal neutron detection efficiency. Detectors coated with Gd can achieve higher efficiencies, but the low-energy signatures are problematic in the presence of background radiations. Microstructured semiconductor neutron detectors (MSNDs) can now achieve a tenfold increase in neutron detection efficiency over the planar diode designs. These semiconductor neutron detectors are fashioned with a matrix of microstructured patterns etched deeply into the semiconductor substrate and, subsequently, backfilled with neutron reactive materials. Intrinsic thermal-neutron detection efficiencies exceeding 35% have been achieved with devices no thicker than 1 mm while operating on less than 5 V, now allowing for instrumentation to be realized with similar performance as 3He gas-filled detectors.

  8. 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.

  9. 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

  10. High-efficiency photovoltaics based on semiconductor nanostructures

    SciTech Connect

    Yu, Paul K.L.; Yu, Edward T.; Wang, Deli

    2011-10-31

    The objective of this project was to exploit a variety of semiconductor nanostructures, specifically semiconductor quantum wells, quantum dots, and nanowires, to achieve high power conversion efficiency in photovoltaic devices. In a thin-film device geometry, the objectives were to design, fabricate, and characterize quantum-well and quantum-dot solar cells in which scattering from metallic and/or dielectric nanostructures was employed to direct incident photons into lateral, optically confined paths within a thin (~1-3um or less) device structure. Fundamental issues concerning nonequilibrium carrier escape from quantum-confined structures, removal of thin-film devices from an epitaxial growth substrate, and coherent light trapping in thin-film photovoltaic devices were investigated. In a nanowire device geometry, the initial objectives were to engineer vertical nanowire arrays to optimize optical confinement within the nanowires, and to extend this approach to core-shell heterostructures to achieve broadspectrum absorption while maintaining high opencircuit voltages. Subsequent work extended this approach to include fabrication of nanowire photovoltaic structures on low-cost substrates.

  11. Broadband high efficiency asymmetric transmission of achiral metamaterials.

    PubMed

    Fan, Wenjun; Wang, Yanrong; Zheng, Ruqiang; Liu, Dahe; Shi, Jinwei

    2015-07-27

    Asymmetric transmission (AT) effect has attracted great interest in recent years, due to its potential application in integrated photonics from GHz to optical frequency. To realize AT effect, numerous metamaterials have been proposed, mainly based on the chirality of the structure. In this paper, we demonstrate that achiral metamaterials can also have AT effect. Furthermore, it is shown that modal conversion is more essential than chirality to achieve AT effect. In particular, we have proposed a mirror symmetric metamaterial with broadband high efficiency AT effect for circular polarization wave operating at THz region. With further optimization of the unit cell, >80% of the central frequency bandwidth and average 74.05 (maximum150) transmission ratio can be obtained. The idea demonstrated here can also be applied to other frequency regions.

  12. 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.

  13. 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.

  14. Energy-Efficient High-Performance Routers

    DTIC Science & Technology

    2012-02-01

    Mishra collaboratively researched TCAM (Ternary Content Addressable Memory) architectures for Internet packet classifiers. The objective was to develop...consumption are achieved. 15. SUBJECT TERMS TCAM (Ternary Content Addressable Memory), Internet packet classifiers 16. SECURITY CLASSIFICATION OF: 17... Internet packets are classified into different flows based on packet header fields and using a table of rules in which each rule is of the form (F,A

  15. Energy-Level Modulation of Small-Molecule Electron Acceptors to Achieve over 12% Efficiency in Polymer Solar Cells.

    PubMed

    Li, Sunsun; Ye, Long; Zhao, Wenchao; Zhang, Shaoqing; Mukherjee, Subhrangsu; Ade, Harald; Hou, Jianhui

    2016-11-01

    Fine energy-level modulations of small-molecule acceptors (SMAs) are realized via subtle chemical modifications on strong electron-withdrawing end-groups. The two new SMAs (IT-M and IT-DM) end-capped by methyl-modified dicycanovinylindan-1-one exhibit upshifted lowest unoccupied molecular orbital (LUMO) levels, and hence higher open-circuit voltages can be observed in the corresponding devices. Finally, a top power conversion efficiency of 12.05% is achieved.

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

    NASA Astrophysics Data System (ADS)

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

    2016-12-01

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

  17. Formal Operational Precocity and Achievement in Biology among Some Nigerian High School Students.

    ERIC Educational Resources Information Center

    Ehindero, Olusola Joseph

    1979-01-01

    Compares the performances on a battery of six Piagetian tasks of 80 Nigerian high school students classified as high and low achievers in biology. The relationship between performance of very bright biology students (high achievers) and intellectual precocity is also investigated. (HM)

  18. The Chinese High School Student's Stress in the School and Academic Achievement

    ERIC Educational Resources Information Center

    Liu, Yangyang; Lu, Zuhong

    2011-01-01

    In a sample of 466 Chinese high school students, we examined the relationships between Chinese high school students' stress in the school and their academic achievements. Regression mixture modelling identified two different classes of the effects of Chinese high school students' stress on their academic achievements. One class contained 87% of…

  19. Beyond Academic Reputation: Factors that Influence the College of First Choice for High Achieving Students

    ERIC Educational Resources Information Center

    Schoenherr, Holly J.

    2009-01-01

    Studies that have investigated college choice factors for high-achieving students repeatedly cite academic reputation as one of the top indicators of choice but have not indicated why some high-achieving students choose to attend universities with a less prestigious reputation than the more highly prestigious options available to them. The purpose…

  20. Does High School Facility Quality Affect Student Achievement? A Two-Level Hierarchical Linear Model

    ERIC Educational Resources Information Center

    Bowers, Alex J.; Urick, Angela

    2011-01-01

    The purpose of this study is to isolate the independent effects of high school facility quality on student achievement using a large, nationally representative U.S. database of student achievement and school facility quality. Prior research on linking school facility quality to student achievement has been mixed. Studies that relate overall…

  1. 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.

  2. The Effects of Web-Based/Non-Web-Based Problem-Solving Instruction and High/Low Achievement on Students' Problem-Solving Ability and Biology Achievement

    ERIC Educational Resources Information Center

    Yu, Wen-Feng; She, Hsiao-Ching; Lee, Yu-Mei

    2010-01-01

    This study investigates the effects of two factors: the mode of problem-solving instruction (i.e. Web-based versus non-Web-based) and the level of academic achievement (i.e. high achievers versus low achievers) on students' problem-solving ability and biology achievement. A quasi-experimental design was used, in which the experimental group…

  3. 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.

  4. Efficient Method of Achieving Agreements between Individuals and Organizations about RFID Privacy

    NASA Astrophysics Data System (ADS)

    Cha, Shi-Cho

    This work presents novel technical and legal approaches that address privacy concerns for personal data in RFID systems. In recent years, to minimize the conflict between convenience and the privacy risk of RFID systems, organizations have been requested to disclose their policies regarding RFID activities, obtain customer consent, and adopt appropriate mechanisms to enforce these policies. However, current research on RFID typically focuses on enforcement mechanisms to protect personal data stored in RFID tags and prevent organizations from tracking user activity through information emitted by specific RFID tags. A missing piece is how organizations can obtain customers' consent efficiently and flexibly. This study recommends that organizations obtain licenses automatically or semi-automatically before collecting personal data via RFID technologies rather than deal with written consents. Such digitalized and standard licenses can be checked automatically to ensure that collection and use of personal data is based on user consent. While individuals can easily control who has licenses and license content, the proposed framework provides an efficient and flexible way to overcome the deficiencies in current privacy protection technologies for RFID systems.

  5. 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.

  6. More Doesn't Mean Better: Larger High Schools and More Courses Do Not Boost Student Achievement in Iowa High Schools

    ERIC Educational Resources Information Center

    Johnson, Jerry

    2006-01-01

    In March 2005, Governor Tom Vilsack and a committee of 12 legislators endorsed proposals intended to "make Iowa's public schools more efficient and improve achievement." Among the proposals was one calling for an education commission that would recommend to the 2007 Legislature a minimum school district and high school size. In light of…

  7. A new high school science program and its effect on student achievement in mathematics and science

    NASA Astrophysics Data System (ADS)

    Goodman, Robert

    Student achievement in mathematics and science is a high educational priority worldwide. The American educational system is not meeting its objectives for these subjects: our students are performing below international standards. The problem is endemic, leading to the conclusion that it is structural. During the last seven years, I have led the creation and implementation of a program whose aim is to address this problem. The structure of this program stresses horizontal and vertical curriculum articulations in order to increase curriculum efficiency and meaningfulness to students. My first aim, in conducting this study, was to determine the program's effectiveness. Since this was a long term program created in a real world environment it would be difficult to use experimental or quasi-experimental analysis. However, I was able to develop a plausible argument for the effectiveness of the program by using two measures to create a baseline for student aptitude and three measures to determine student achievement. Together these showed that the school's students, while typical of those in New Jersey, achieved very positive results in mathematic and science. The likelihood that the new program was responsible for this was enhanced by the fact that the verbal and mathematical aptitudes of the students were comparable, but their achievement in areas outside mathematic and science were not exceptional. My second aim was to provide documentation so that the program could be replicated at other schools. This included the scope and sequence of the mathematics and science courses; the curricula of the physics courses; an explanation the pedagogical approach used in the physics courses, and sample chapters of a textbook being written to support the first year physic course. Whiles those documents supply a snapshot of the current state of the program; they are probably insufficient to replicate it. This would also require an understanding of the program's rationale. Towards this

  8. Metering Best Practices, A Guide to Achieving Utility Resource Efficiency, Release 2.0

    SciTech Connect

    Sullivan, Greg; Hunt, W. D.; Pugh, Ray; Sandusky, William F.; Koehler, Theresa M.; Boyd, Brian K.

    2011-08-31

    This release is an update and expansion of the information provided in Release 1.0 of the Metering Best Practice Guide that was issued in October 2007. This release, as was the previous release, was developed under the direction of the U.S. Department of Energy's Federal Energy Management Program (FEMP). The mission of FEMP is to facilitate the Federal Government's implementation of sound cost-effective energy management and investment practices to enhance the nation's energy security and environmental stewardship. Each of these activities is directly related to achieving requirements set forth in the Energy Policy Acts of 1992 and 2005, the Energy Independence and Security Act (EISA) of 2007, and the goals that have been established in Executive Orders 13423 and 13514 - and also those practices that are inherent in sound management of Federal financial and personnel resources.

  9. Survey of light sources for image display systems to achieve brightness with efficient energy

    NASA Astrophysics Data System (ADS)

    Cheng, Dah Yu; Chen, Li-Min

    1995-04-01

    This paper will review the currently available light sources, and also introduces a new, patented compound orthogonal parabolic reflector to be integrated with the light source, which focuses a relatively large light source into a very small point. The reflector creates a nearly ideal intense point source for all next generation image display systems. The proposed system is not limited by the radiation source whether it is a short arc lamp or a long tungsten filament lamp. Our technologies take the finite size of radiation sources into account to address the common problem for all reflector lamp systems, i.e., intensity and uniformity (dark hole). Successful examples will be shown on how to make the efficient intense light source match the requirements of LCD and DMD display systems. A method for reducing U.V. and I.R. radiation will also be demonstrated.

  10. Operations & Maintenance Best Practices - A Guide to Achieving Operational Efficiency (Release 3)

    SciTech Connect

    Sullivan, Greg; Pugh, Ray; Melendez, Aldo P.; Hunt, W. D.

    2010-08-04

    This guide highlights operations and maintenance programs targeting energy and water efficiency that are estimated to save 5% to 20% on energy bills without a significant capital investment. The purpose of this guide is to provide you, the Operations and Maintenance (O&M)/Energy manager and practitioner, with useful information about O&M management, technologies, energy and water efficiency, and cost-reduction approaches. To make this guide useful and to reflect your needs and concerns, the authors met with O&M and Energy managers via Federal Energy Management Program (FEMP) workshops. In addition, the authors conducted extensive literature searches and contacted numerous vendors and industry experts. The information and case studies that appear in this guide resulted from these activities. It needs to be stated at the outset that this guide is designed to provide information on effective O&M as it applies to systems and equipment typically found at Federal facilities. This guide is not designed to provide the reader with step-by-step procedures for performing O&M on any specific piece of equipment. Rather, this guide first directs the user to the manufacturer's specifications and recommendations. In no way should the recommendations in this guide be used in place of manufacturer's recommendations. The recommendations in this guide are designed to supplement those of the manufacturer, or, as is all too often the case, provide guidance for systems and equipment for which all technical documentation has been lost. As a rule, this guide will first defer to the manufacturer's recommendations on equipment operation and maintenance.

  11. High efficiency hybrid silicon nanopillar-polymer solar cells.

    PubMed

    Pudasaini, Pushpa Raj; Ruiz-Zepeda, Francisco; Sharma, Manisha; Elam, David; Ponce, Arturo; Ayon, Arturo A

    2013-10-09

    Recently, inorganic/organic hybrid solar cells have been considered as a viable alternative for low-cost photovoltaic devices because the Schottky junction between inorganic and organic materials can be formed employing low temperature processing methods. We present an efficient hybrid solar cell based on highly ordered silicon nanopillars (SiNPs) and poly(3,4-ethylene-dioxythiophene):polystyrenesulfonate (PEDOT:PSS). The proposed device is formed by spin coating the organic polymer PEDOT:PSS on a SiNP array fabricated using metal assisted electroless chemical etching process. The characteristics of the hybrid solar cells are investigated as a function of SiNP height. A maximum power conversion efficiency (PCE) of 9.65% has been achieved for an optimized SiNP array hybrid solar cell with nanopillar height of 400 nm, despite the absence of a back surface field enhancement. The effect of an ultrathin atomic layer deposition (ALD), grown aluminum oxide (Al2O3), as a passivation layer (recombination barrier) has also been studied for the enhanced electrical performance of the device. With the inclusion of the ultrathin ALD deposited Al2O3 between the SiNP array textured surface and the PEDOT:PSS layer, the PCE of the fabricated device was observed to increase to 10.56%, which is ∼10% greater than the corresponding device without the Al2O3 layer. The device described herein is considered to be promising toward the realization of a low-cost, high-efficiency inorganic/organic hybrid solar cell.

  12. Achieving High Strength and High Ductility in Friction Stir-Processed Cast Magnesium Alloy

    NASA Astrophysics Data System (ADS)

    Yuan, Wei; Panigrahi, Sushanta K.; Mishra, Rajiv S.

    2013-08-01

    Friction stir processing (FSP) is emerging as an effective tool for microstructural modification and property enhancement. As-cast AZ91 magnesium alloy was friction stir processed with one-pass and two-pass to examine the influence of processing conditions on microstructural evolution and corresponding mechanical properties. Grain refinement accompanied with development of strong basal texture was observed for both processing conditions. Ultrafine-grained (UFG) AZ91 was achieved under two-pass FSP with fine precipitates distributed on the grain boundary. The processed UFG AZ91 exhibited a high tensile strength of ~435 MPa (117 pct improvement) and tensile fracture elongation of ~23 pct. The promising combination of strength and ductility is attributed to the elimination of casting porosity, and high density of fine precipitates in an UFG structure with quite low dislocation density. The effects of grain size, precipitate, and texture on deformation behavior have been discussed.

  13. 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.

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

    PubMed

    Budzianowski, Jaromir

    2010-01-01

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

  15. An Analysis of Java Programming Behaviors, Affect, Perceptions, and Syntax Errors among Low-Achieving, Average, and High-Achieving Novice Programmers

    ERIC Educational Resources Information Center

    Rodrigo, Ma. Mercedes T.; Andallaza, Thor Collin S.; Castro, Francisco Enrique Vicente G.; Armenta, Marc Lester V.; Dy, Thomas T.; Jadud, Matthew C.

    2013-01-01

    In this article we quantitatively and qualitatively analyze a sample of novice programmer compilation log data, exploring whether (or how) low-achieving, average, and high-achieving students vary in their grasp of these introductory concepts. High-achieving students self-reported having the easiest time learning the introductory programming…

  16. Energy Efficient High-Pressure Turbine Leakage Technology Report

    NASA Technical Reports Server (NTRS)

    Gardner, W. B.

    1980-01-01

    The leakage test program was one of such supporting technology programs structured to provide guidance to the Energy Efficient Engine High Pressure Turbine Component Design Effort. Leakage reduction techniques were identified and evaluated. Test models were used to simulate component leak paths and to evaluate leakage reduction techniques. These models simulated the blade/disk attachment, the vane inner platform attachment, and the vane outer platform attachment combined with the blade outer airseal. Disk blade attachment testing indicated that leakage in this area could be reduced to very low levels by paying careful attention to the tolerances along the contact surface between the blade vibration damper and the blade platform contact surface. The aim of feather seal testing was to achieve a goal for an effective leakage gap of one mil (.001 inch) per inch of feather seal length. Results indicated that effective gaps even below the goal level were achievable by (1) maintaining close tolerances between feather seals and their slots to minimize end gaps and limit seal rotation, (2) avoiding feather seal overlap, and (3) minimizing feather seal intersections. W seals were shown to be effective leakage control devices. Wire rope, in its present state of development, was shown not to be an effective sealing concept for application to the component design.

  17. The use of ECDIS equipment to achieve an optimum value for energy efficiency operation index

    NASA Astrophysics Data System (ADS)

    Acomi, N.; Acomi, O. C.; Stanca, C.

    2015-11-01

    To reduce air pollution produced by ships, the International Maritime Organization has developed a set of technical, operational and management measures. The subject of our research addresses the operational measures for minimizing CO2 air emissions and the way how the emission value could be influenced by external factors regardless of ship-owners’ will. This study aims to analyse the air emissions for a loaded voyage leg performed by an oil tanker. The formula that allows us to calculate the predicted Energy Efficiency Operational Index involves the estimation of distance and fuel consumption, while the quantity of cargo is known. The electronic chart display and information system, ECDIS Simulation Software, will be used for adjusting the passage plan in real time, given the predicted severe environmental conditions. The distance will be determined using ECDIS, while the prediction of the fuel consumption will consider the sea trial and the vessel experience records. That way it will be possible to compare the estimated EEOI value in the case of great circle navigation in adverse weather condition with the estimated EEOI value for weather navigation.

  18. 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

  19. Efficient high-peak-power and high-repetition-rate eye-safe laser using an intracavity KTP OPO

    NASA Astrophysics Data System (ADS)

    Guo, J.; He, G. Y.; Jiao, Z. X.; Wang, B.

    2015-03-01

    An efficient high-peak-power and high-repetition-rate intracavity KTP optical parametric oscillator pumped by a Q-switched Nd:YVO4 laser is demonstrated. We achieved 1.5 W output power of 1.5 μm at 10 kHz repetition rate with the pulse duration of 6 ns. The maximum peak power of 25 kW and the maximum pulse energy of 150 μJ have been obtained. The maximum conversion efficiency of 9.5% is achieved with respect to a laser diode power of 10.5 W.

  20. High efficiency long pulse gigawatt sources of HPM radiation

    NASA Astrophysics Data System (ADS)

    Arman, M. Joseph

    1999-05-01

    The High Power Microwave (HPM) technology has advanced tremendously in the last five decades. What started out as a mere passive tool in the form of radar for detecting airborne objects during the second world war, has grown to be an active vehicle that can influence and impact its target. Progress has been made in all fronts. The peak radiated power has gone up several orders of magnitude to several gigawatts, the efficiency has grown by a wide margin, and the total energy radiated for pulsed sources has grown to several hundreds of Jules per pulse. Major obstacles still exist. The number of sources that have already achieved one gigawatt or higher is too great to cover here. In what follows, we will briefly describe the sources that have radiated one gigawatt or higher with a pulselength of 300 ns or longer, and an rms efficiency of 10% or higher. We also address the obstacles lying ahead and suggest possible means of overcoming them. The sources presented are the Relativistic Klystron Oscillator (RKO), the Magnetically Insulated Line Oscillator (MILO), and the Tapered Magnetically Insulated Line Oscillator (TMILO).

  1. Highly Efficient Small Form Factor LED Retrofit Lamp

    SciTech Connect

    Steven Allen; Fred Palmer; Ming Li

    2011-09-11

    This report summarizes work to develop a high efficiency LED-based MR16 lamp downlight at OSRAM SYLVANIA under US Department of Energy contract DE-EE0000611. A new multichip LED package, electronic driver, and reflector optic were developed for these lamps. At steady-state, the lamp luminous flux was 409 lumens (lm), luminous efficacy of 87 lumens per watt (LPW), CRI (Ra) of 87, and R9 of 85 at a correlated color temperature (CCT) of 3285K. The LED alone achieved 120 lumens per watt efficacy and 600 lumen flux output at 25 C. The driver had 90% electrical conversion efficiency while maintaining excellent power quality with power factor >0.90 at a power of only 5 watts. Compared to similar existing MR16 lamps using LED sources, these lamps had much higher efficacy and color quality. The objective of this work was to demonstrate a LED-based MR16 retrofit lamp for replacement of 35W halogen MR16 lamps having (1) luminous flux of 500 lumens, (2) luminous efficacy of 100 lumens per watt, (3) beam angle less than 40{sup o} and center beam candlepower of at least 1000 candelas, and (4) excellent color quality.

  2. Processes for producing low cost, high efficiency silicon solar cells

    DOEpatents

    Rohatgi, Ajeet; Chen, Zhizhang; Doshi, Parag

    1996-01-01

    Processes which utilize rapid thermal processing (RTP) are provided for inexpensively producing high efficiency silicon solar cells. The RTP processes preserve minority carrier bulk lifetime .tau. and permit selective adjustment of the depth of the diffused regions, including emitter and back surface field (bsf), within the silicon substrate. Silicon solar cell efficiencies of 16.9% have been achieved. In a first RTP process, an RTP step is utilized to simultaneously diffuse phosphorus and aluminum into the front and back surfaces, respectively, of a silicon substrate. Moreover, an in situ controlled cooling procedure preserves the carrier bulk lifetime .tau. and permits selective adjustment of the depth of the diffused regions. In a second RTP process, both simultaneous diffusion of the phosphorus and aluminum as well as annealing of the front and back contacts are accomplished during the RTP step. In a third RTP process, the RTP step accomplishes simultaneous diffusion of the phosphorus and aluminum, annealing of the contacts, and annealing of a double-layer antireflection/passivation coating SiN/SiO.sub.x.

  3. Depth Filters Containing Diatomite Achieve More Efficient Particle Retention than Filters Solely Containing Cellulose Fibers

    PubMed Central

    Buyel, Johannes F.; Gruchow, Hannah M.; Fischer, Rainer

    2015-01-01

    The clarification of biological feed stocks during the production of biopharmaceutical proteins is challenging when large quantities of particles must be removed, e.g., when processing crude plant extracts. Single-use depth filters are often preferred for clarification because they are simple to integrate and have a good safety profile. However, the combination of filter layers must be optimized in terms of nominal retention ratings to account for the unique particle size distribution in each feed stock. We have recently shown that predictive models can facilitate filter screening and the selection of appropriate filter layers. Here we expand our previous study by testing several filters with different retention ratings. The filters typically contain diatomite to facilitate the removal of fine particles. However, diatomite can interfere with the recovery of large biopharmaceutical molecules such as virus-like particles and aggregated proteins. Therefore, we also tested filtration devices composed solely of cellulose fibers and cohesive resin. The capacities of both filter types varied from 10 to 50 L m−2 when challenged with tobacco leaf extracts, but the filtrate turbidity was ~500-fold lower (~3.5 NTU) when diatomite filters were used. We also tested pre–coat filtration with dispersed diatomite, which achieved capacities of up to 120 L m−2 with turbidities of ~100 NTU using bulk plant extracts, and in contrast to the other depth filters did not require an upstream bag filter. Single pre-coat filtration devices can thus replace combinations of bag and depth filters to simplify the processing of plant extracts, potentially saving on time, labor and consumables. The protein concentrations of TSP, DsRed and antibody 2G12 were not affected by pre-coat filtration, indicating its general applicability during the manufacture of plant-derived biopharmaceutical proteins. PMID:26734037

  4. 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.

  5. 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.

  6. Evaluation of Small Molecules as Front Cell Donor Materials for High-Efficiency Tandem Solar Cells.

    PubMed

    Zhang, Qian; Wan, Xiangjian; Liu, Feng; Kan, Bin; Li, Miaomiao; Feng, Huanran; Zhang, Hongtao; Russell, Thomas P; Chen, Yongsheng

    2016-08-01

    Three small molecules as front cell donors for tandem cells are thoroughly evaluated and a high power conversion efficiency of 11.47% is achieved, which demonstrates that the oligomer-like small molecules offer a good choice for high-performance tandem solar cells.

  7. The Effect of the Time Management Art on Academic Achievement among High School Students in Jordan

    ERIC Educational Resources Information Center

    Al-Zoubi, Maysoon

    2016-01-01

    This study aimed at recognizing the effect of the Time Management Art on academic achievement among high school students in the Hashemite Kingdom of Jordan. The researcher employed the descriptive-analytic research to achieve the purpose of the study where he chose a sample of (2000) high school female and male students as respondents to the…

  8. Effects of a Collaborative Science Intervention on High Achieving Students' Learning Anxiety and Attitudes toward Science

    ERIC Educational Resources Information Center

    Hong, Zuway-R.

    2010-01-01

    This study investigated the effects of a collaborative science intervention on high achieving students' learning anxiety and attitudes toward science. Thirty-seven eighth-grade high achieving students (16 boys and 21 girls) were selected as an experimental group who joined a 20-week collaborative science intervention, which integrated and utilized…

  9. Individual and Longitudinal Differences among High and Low-Achieving, LD, and ADHD L2 Learners

    ERIC Educational Resources Information Center

    Sparks, Richard L.; Humbach, Nancy; Javorsky, James

    2008-01-01

    High-achieving (HA) and low-achieving (LA), learning disabled (LD), and attention deficit hyperactivity disorder (ADHD) high school students were followed over two years of L2 study and compared on measures of L1 literacy (reading and writing) in elementary school, L1 cognitive ability, L2 aptitude, oral and written L2 proficiency, and L2 word…

  10. International Note: Between-Domain Relations of Chinese High School Students' Academic Achievements

    ERIC Educational Resources Information Center

    Yangyang, Liu

    2012-01-01

    The present study examined the between-domain relations of Chinese high school students' academic achievements. In a sample of 1870 Chinese 10th grade students, the results indicated that Chinese high school students' academic achievements were correlated across nine subjects. In line with the previous Western findings, the findings suggested that…

  11. A Longitudinal Investigation of Project-Based Instruction and Student Achievement in High School Social Studies

    ERIC Educational Resources Information Center

    Summers, Emily J.; Dickinson, Gail

    2012-01-01

    This longitudinal study focused on how project-based instruction (PBI) influenced secondary social studies students' academic achievement and promoted College and Career Readiness (CCR). We explored and compared student achievement in a PBI high school versus a traditional instruction high school within the same rural school district. While…

  12. Parent-Child Relations and Psychological Adjustment among High-Achieving Chinese and European American Adolescents

    ERIC Educational Resources Information Center

    Qin, Desiree Baolian; Rak, Eniko; Rana, Meenal; Donnellan, M. Brent

    2012-01-01

    Chinese American students are often perceived as problem-free high achievers. Recent research, however, suggests that high-achieving Chinese American students can experience elevated levels of stress, especially comparing to their peers from other ethnic groups. In this paper, we examine how family dynamics may influence psychological adjustment…

  13. High-Achieving and Average Students' Reading Growth: Contrasting School and Summer Trajectories

    ERIC Educational Resources Information Center

    Rambo-Hernandez, Karen E.; McCoach, D. Betsy

    2015-01-01

    Much is unknown about how initially high-achieving students grow academically, especially given the measurement issues inherent in assessing growth for the highest performing students. This study compared initially high-achieving and average students' growth in reading (in a cohort of third-grade students from 2,000 schools) over 3 years.…

  14. Highly efficient, high speed vertical photodiodes based on few-layer MoS2

    NASA Astrophysics Data System (ADS)

    Li, Zhen; Chen, Jihan; Dhall, Rohan; Cronin, Stephen B.

    2017-03-01

    Layered transition metal dichalcogenides, such as MoS2, have recently emerged as a promising material system for electronic and optoelectronic applications. The two-dimensional nature of these materials enables facile integration for vertical device design with novel properties. Here, we report highly efficient photocurrent generation from vertical MoS2 devices fabricated using asymmetric metal contacts, exhibiting an external quantum efficiency of up to 7%. Compared to in-plane MoS2 devices, the vertical design of these devices has a much larger junction area, which is essential for achieving highly efficient photovoltaic devices. Photocurrent and photovoltage spectra are measured over the photon energy range from 1.25 to 2.5 eV, covering both the 1.8 eV direct K-point optical transition and the 1.3 eV Σ-point indirect transition in MoS2. Photocurrent peaks corresponding to both direct and indirect transitions are observed in the photocurrent spectra and exhibit different photovoltage-current characteristics. Compared to previous in-plane devices, a substantially shorter photoresponse time of 7.3 μs is achieved due to fast carrier sweeping in the vertical devices, which exhibit a -3 dB cutoff frequency of 48 kHz.

  15. 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.

  16. The Meaning High-Achieving African-American Males in an Urban High School Ascribe to Mathematics

    ERIC Educational Resources Information Center

    Thompson, LaTasha; Davis, Julius

    2013-01-01

    Many researchers, educators, administrators, policymakers and members of the general public doubt the prevalence of high-achieving African-American males in urban high schools capable of excelling in mathematics. As part of a larger study, the current study explored the educational experiences of four high-achieving African-American males…

  17. Efficient and anonymous two-factor user authentication in wireless sensor networks: achieving user anonymity with lightweight sensor computation.

    PubMed

    Nam, Junghyun; Choo, Kim-Kwang Raymond; Han, Sangchul; Kim, Moonseong; Paik, Juryon; Won, Dongho

    2015-01-01

    A smart-card-based user authentication scheme for wireless sensor networks (hereafter referred to as a SCA-WSN scheme) is designed to ensure that only users who possess both a smart card and the corresponding password are allowed to gain access to sensor data and their transmissions. Despite many research efforts in recent years, it remains a challenging task to design an efficient SCA-WSN scheme that achieves user anonymity. The majority of published SCA-WSN schemes use only lightweight cryptographic techniques (rather than public-key cryptographic techniques) for the sake of efficiency, and have been demonstrated to suffer from the inability to provide user anonymity. Some schemes employ elliptic curve cryptography for better security but require sensors with strict resource constraints to perform computationally expensive scalar-point multiplications; despite the increased computational requirements, these schemes do not provide user anonymity. In this paper, we present a new SCA-WSN scheme that not only achieves user anonymity but also is efficient in terms of the computation loads for sensors. Our scheme employs elliptic curve cryptography but restricts its use only to anonymous user-to-gateway authentication, thereby allowing sensors to perform only lightweight cryptographic operations. Our scheme also enjoys provable security in a formal model extended from the widely accepted Bellare-Pointcheval-Rogaway (2000) model to capture the user anonymity property and various SCA-WSN specific attacks (e.g., stolen smart card attacks, node capture attacks, privileged insider attacks, and stolen verifier attacks).

  18. Efficient and Anonymous Two-Factor User Authentication in Wireless Sensor Networks: Achieving User Anonymity with Lightweight Sensor Computation

    PubMed Central

    Nam, Junghyun; Choo, Kim-Kwang Raymond; Han, Sangchul; Kim, Moonseong; Paik, Juryon; Won, Dongho

    2015-01-01

    A smart-card-based user authentication scheme for wireless sensor networks (hereafter referred to as a SCA-WSN scheme) is designed to ensure that only users who possess both a smart card and the corresponding password are allowed to gain access to sensor data and their transmissions. Despite many research efforts in recent years, it remains a challenging task to design an efficient SCA-WSN scheme that achieves user anonymity. The majority of published SCA-WSN schemes use only lightweight cryptographic techniques (rather than public-key cryptographic techniques) for the sake of efficiency, and have been demonstrated to suffer from the inability to provide user anonymity. Some schemes employ elliptic curve cryptography for better security but require sensors with strict resource constraints to perform computationally expensive scalar-point multiplications; despite the increased computational requirements, these schemes do not provide user anonymity. In this paper, we present a new SCA-WSN scheme that not only achieves user anonymity but also is efficient in terms of the computation loads for sensors. Our scheme employs elliptic curve cryptography but restricts its use only to anonymous user-to-gateway authentication, thereby allowing sensors to perform only lightweight cryptographic operations. Our scheme also enjoys provable security in a formal model extended from the widely accepted Bellare-Pointcheval-Rogaway (2000) model to capture the user anonymity property and various SCA-WSN specific attacks (e.g., stolen smart card attacks, node capture attacks, privileged insider attacks, and stolen verifier attacks). PMID:25849359

  19. Efficiency of pulse high-current generator energy transfer into plasma liner energy

    NASA Astrophysics Data System (ADS)

    Oreshkin, V. I.

    2013-08-01

    The efficiency of capacitor-bank energy transfer from a high-current pulse generator into kinetic energy of a plasma liner has been analyzed. The analysis was performed using a model including the circuit equations and equations of the cylindrical shell motion. High efficiency of the energy transfer into kinetic energy of the liner is shown to be achieved only by a low-inductance generator. We considered an "ideal" liner load in which the load current is close to zero in the final of the shell compression. This load provides a high (up to 80%) efficiency of energy transfer and higher stability when compressing the liner.

  20. Efficient binning for bitmap indices on high-cardinality attributes

    SciTech Connect

    Rotem, Doron; Stockinger, Kurt; Wu, Kesheng

    2004-11-17

    Bitmap indexing is a common technique for indexing high-dimensional data in data warehouses and scientific applications. Though efficient for low-cardinality attributes, query processing can be rather costly for high-cardinality attributes due to the large storage requirements for the bitmap indices. Binning is a common technique for reducing storage costs of bitmap indices. This technique partitions the attribute values into a number of ranges, called bins, and uses bitmap vectors to represent bins (attribute ranges) rather than distinct values. Although binning may reduce storage costs, it may increase the access costs of queries that do not fall on exact bin boundaries (edge bins). For this kind of queries the original data values associated with edge bins must be accessed, in order to check them against the query constraints.In this paper we study the problem of finding optimal locations for the bin boundaries in order to minimize these access costs subject to storage constraints. We propose a dynamic programming algorithm for optimal partitioning of attribute values into bins that takes into account query access patterns as well as data distribution statistics. Mathematical analysis and experiments on real life data sets show that the optimal partitioning achieved by this algorithm can lead to a significant improvement in the access costs of bitmap indexing systems for high-cardinality attributes.

  1. 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.

  2. Highly efficient terahertz wave modulators by photo-excitation of organics/silicon bilayers

    SciTech Connect

    Yoo, Hyung Keun; Kang, Chul; Hwang, In-Wook; Yoon, Youngwoon; Lee, Kiejin; Kee, Chul-Sik; Lee, Joong Wook

    2014-07-07

    Using hybrid bilayer systems comprising a molecular organic semiconductor and silicon, we achieve optically controllable active terahertz (THz) modulators that exhibit extremely high modulation efficiencies. A modulation efficiency of 98% is achieved from thermally annealed C{sub 60}/silicon bilayers, due to the rapid photo-induced electron transfer from the excited states of the silicon onto the C{sub 60} layer. Furthermore, we demonstrate the broadband modulation of THz waves. The cut-off condition of the system that is determined by the formation of efficient charge separation by the photo-excitation is highly variable, changing the system from insulating to metallic. The phenomenon enables an extremely high modulation bandwidth and rates of electromagnetic waves of interest. The realization of near-perfect modulation efficiency in THz frequencies opens up the possibilities of utilizing active modulators for THz spectroscopy and communications.

  3. Achieving efficient protein expression in Trichoderma reesei by using strong constitutive promoters

    PubMed Central

    2012-01-01

    Backgrounds The fungus Trichoderma reesei is an important workhorse for expression of homologous or heterologous genes, and the inducible cbh1 promoter is generally used. However, constitutive expression is more preferable in some cases than inducible expression that leads to production of unwanted cellulase components. In this work, constitutive promoters of T. reesei were screened and successfully used for high level homologous expression of xylanase II. Results The transcriptional profiles of 13 key genes that participate in glucose metabolism in T. reesei were analyzed by quantitative real-time reverse-transcription polymerase chain reaction (RT-qPCR). The results indicated that the mRNA levels of pdc (encoding pyruvate decarboxylase) and eno (encoding enolase) genes were much higher than other genes under high glucose conditions. Recombinant T. reesei strains that homologously expressed xylanase II were constructed by using the promoters of the pdc and eno genes, and they respectively produced 9266 IU/ml and 8866 IU/ml of xylanase activities in the cultivation supernatant in a medium with high glucose concentration. The productivities of xylanase II were 1.61 g/L (with the pdc promoter) and 1.52 g/L (with the eno promoter), approximately accounted for 83% and 82% of the total protein secreted by T. reesei, respectively. Conclusions This work demonstrates the screening of constitutive promoters by using RT-qPCR in T. reesei, and has obtained the highest expression of recombinant xylanase II to date by using these promoters. PMID:22709462

  4. 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.

  5. Limits on Achievable Dimensional and Photon Efficiencies with Intensity-Modulation and Photon-Counting Due to Non-Ideal Photon-Counter Behavior

    NASA Technical Reports Server (NTRS)

    Moision, Bruce; Erkmen, Baris I.; Farr, William; Dolinar, Samuel J.; Birnbaum, Kevin M.

    2012-01-01

    An ideal intensity-modulated photon-counting channel can achieve unbounded photon information efficiencies (PIEs). However, a number of limitations of a physical system limit the practically achievable PIE. In this paper, we discuss several of these limitations and illustrate their impact on the channel. We show that, for the Poisson channel, noise does not strictly bound PIE, although there is an effective limit, as the dimensional information efficiency goes as e[overline] e PIE beyond a threshold PIE. Since the Holevo limit is bounded in the presence of noise, this illustrates that the Poisson approximation is invalid at large PIE for any number of noise modes. We show that a finite transmitter extinction ratio bounds the achievable PIE to a maximum that is logarithmic in the extinction ratio. We show how detector jitter limits the ability to mitigate noise in the PPM signaling framework. We illustrate a method to model detector blocking when the number of detectors is large, and illustrate mitigation of blocking with spatial spreading and altering. Finally, we illustrate the design of a high photon efficiency system using state-of-the-art photo-detectors and taking all these effects into account.

  6. Design requirements for high-efficiency high concentration ratio space solar cells

    NASA Technical Reports Server (NTRS)

    Rauschenbach, H.; Patterson, R.

    1980-01-01

    A miniaturized Cassegrainian concentrator system concept was developed for low cost, multikilowatt space solar arrays. The system imposes some requirements on solar cells which are new and different from those imposed for conventional applications. The solar cells require a circular active area of approximately 4 mm in diameter. High reliability contacts are required on both front and back surfaces. The back area must be metallurgically bonded to a heat sink. The cell should be designed to achieve the highest practical efficiency at 100 AMO suns and at 80 C. The cell design must minimize losses due to nonuniform illumination intensity and nonnormal light incidence. The primary radiation concern is the omnidirectional proton environment.

  7. High efficiency and high-energy intra-cavity beam shaping laser

    NASA Astrophysics Data System (ADS)

    Yang, Hailong; Meng, Junqing; Chen, Weibiao

    2015-09-01

    We present a technology of intra-cavity laser beam shaping with theory and experiment to obtain a flat-top-like beam with high-pulse energy. A radial birefringent element (RBE) was used in a crossed Porro prism polarization output coupling resonator to modulate the phase delay radially. The reflectively of a polarizer used as an output mirror was variable radially. A flat-top-like beam with 72.5 mJ, 11 ns at 20 Hz was achieved by a side-pumped Nd:YAG zigzag slab laser, and the optical-to-optical conversion efficiency was 17.3%.

  8. High-Efficiency Nitride-Base Photonic Crystal Light Sources

    SciTech Connect

    James Speck; Evelyn Hu; Claude Weisbuch; Yong-Seok Choi; Kelly McGroddy; Gregor Koblmuller; Elison Matioli; Elizabeth Rangel; Fabian Rol; Dobri Simeonov

    2010-01-31

    light into the active region of solar cells; increasing the efficiency of the phosphorous light conversion in white light LEDs etc. In addition to the technology of embedded PhC LEDs, we demonstrate a technique for improvement of the light extraction and emission directionality for existing flip-chip microcavity (thin) LEDs by introducing PhC grating into the top n-contact. Although, the performances of these devices in terms of increase of the extraction efficiency are not significantly superior compared to those obtained by other techniques like surface roughening, the use of PhC offers some significant advantages such as improved and controllable emission directionality and a process that is directly applicable to any material system. The PhC microcavity LEDs have also potential for industrial implementation as the fabrication process has only minor differences to that already used for flip-chip thin LEDs. Finally, we have demonstrated that achieving good electrical properties and high fabrication yield for these devices is straightforward.

  9. 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.

  10. Substrate-constituted three-liquid-phase system: a green, highly efficient and recoverable platform for interfacial enzymatic reactions.

    PubMed

    Li, Zhigang; Chen, Huayong; Wang, Weifei; Qu, Man; Tang, Qingyun; Yang, Bo; Wang, Yonghua

    2015-08-21

    Highly efficient interfacial enzymatic hydrolysis of oil was achieved in a three-liquid-phase system, wherein the substrate constituted one of the phases. The enlarged interfacial area and relieved product inhibition were responsible for the high catalytic efficiency. Convenient product isolation and the high reusability of the enzyme were also demonstrated.

  11. 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

  12. 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.

  13. An 18.2%-efficient black-silicon solar cell achieved through control of carrier recombination in nanostructures.

    PubMed

    Oh, Jihun; Yuan, Hao-Chih; Branz, Howard M

    2012-11-01

    Silicon nanowire and nanopore arrays promise to reduce manufacturing costs and increase the power conversion efficiency of photovoltaic devices. So far, however, photovoltaic cells based on nanostructured silicon exhibit lower power conversion efficiencies than conventional cells due to the enhanced photocarrier recombination associated with the nanostructures. Here, we identify and separately measure surface recombination and Auger recombination in wafer-based nanostructured silicon solar cells. By identifying the regimes of junction doping concentration in which each mechanism dominates, we were able to design and fabricate an independently confirmed 18.2%-efficient nanostructured 'black-silicon' cell that does not need the antireflection coating layer(s) normally required to reach a comparable performance level. Our results suggest design rules for efficient high-surface-area solar cells with nano- and microstructured semiconductor absorbers.

  14. A high-efficiency 59- to 64-GHz TWT for intersatellite communications

    NASA Technical Reports Server (NTRS)

    Wilson, Jeffrey D.; Ramins, Peter; Force, Dale A.; Limburg, Helen C.; Tammaru, Ivo

    1991-01-01

    The design of a 75-W, 59- to 64- GHz TWT with a predicted overall efficiency in excess of 40 percent is described. This intersatellite communications TWT, designated Model 961HA, employs a coupled-cavity slow-wave structure with a two-step velocity taper and an isotropic graphite multistage depressed collector (MDC). Because the RF efficiency of this TWT is less than 8 percent, an MDC design providing a very high collector efficiency was necessary to achieve the overall efficiency goal of 40 percent.

  15. High-efficiency quantum state transfer and quantum memory using a mechanical oscillator

    NASA Astrophysics Data System (ADS)

    Sete, Eyob A.; Eleuch, H.

    2015-03-01

    We analyze an optomechanical system that can be used to efficiently transfer a quantum state between an optical cavity and a distant mechanical oscillator coupled to a second optical cavity. We show that for a moderate mechanical Q factor it is possible to achieve a transfer efficiency of 99.4 % by using adjustable cavity damping rates and destructive interference. We also show that the quantum mechanical oscillator can be used as a quantum memory device with an efficiency of 96 % employing a pulsed optomechanical coupling. Although the mechanical dissipation slightly decreases the efficiency, its effect can be significantly reduced by designing a high-Q mechanical oscillator.

  16. 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.

  17. 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...

  18. 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...

  19. 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...

  20. 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...

  1. 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.

  2. Compact, highly efficient ytterbium doped bismuthate glass waveguide laser.

    PubMed

    Mary, R; Beecher, S J; Brown, G; Thomson, R R; Jaque, D; Ohara, S; Kar, A K

    2012-05-15

    Laser slope efficiencies close to the quantum defect limit and in excess of 78% have been obtained from an ultrafast laser inscribed buried channel waveguide fabricated in a ytterbium-doped bismuthate glass. The simultaneous achievement of low propagation losses and preservation of the fluorescence properties of ytterbium ions is the basis of the outstanding laser performance.

  3. The impact of collective teacher efficacy on student achievement in high school science

    NASA Astrophysics Data System (ADS)

    Burcham, Mark W.

    This dissertation was designed to examine the impact of collective teacher efficacy on high school science achievement by looking at relationships among collective teacher efficacy, its two constructs, group competence and group task analysis, and high school science achievement scores at four rural high schools in Northwestern North Carolina. The researcher gathered historical test data from the testing coordinator from the school system and then administered the Collective Teacher Efficacy Instrument, developed by Goddard, Hoy, and Woolfolk Hoy (2000), to 24 science teachers from the four high schools. Using this information, the researcher conducted statistical analyses to determine the relationships among collective teacher efficacy, group competence, and group task analysis as compared with the tested science curriculum (physical science, biology, chemistry, and physics). The researcher also examined which construct was the most contributing factor and examined differences in efficacy levels and student achievement levels at each high school. Analysis of the data from this study indicated collective teacher efficacy, as well as its two constructs, group competence and group task analysis, does have a positive impact on student achievement in high school science. Analysis of the data revealed group competence is the major contributing factor for student achievement in biology and group task analysis is the major contributing factor for student achievement in physical science, chemistry, and physics. Further analysis of the data in this study, also revealed that the two high schools with the highest levels of collective teacher efficacy had the highest levels of student achievement.

  4. Concentrating and spectrum splitting optical device in high efficiency CPV module with five bandgaps

    NASA Astrophysics Data System (ADS)

    Taudien, Jerker Y.; Kern, Ludwig A.

    2013-09-01

    There is a need for a high efficiency low cost solar energy conversion system. Currently, most concentrating photovoltaic (CPV) systems concentrate the solar spectrum onto triple junction cells to strive for high conversion efficiencies and low cost. Other approaches to high efficiency use spectrum splitting. Triple junction systems are limited in efficiency and spectrum splitting systems are usually too costly for mass production. The objective is to design a spectrum splitting solar concentrator, using reverse ray tracing methods, to overcome the efficiency and cost limitations of current systems by using a single low cost optical device to concentrate and split the solar spectrum onto a large number of target photovoltaic (PV) cells. Dispersive properties of standard optical materials, such as glass or plastic, are utilized to achieve the desired spectral separation. Reverse ray tracing is used to simultaneously optimize the shape of the top and bottom interfaces of the solar concentrator to achieve the desired split spectrum at the target PV cells. Additional strategies to increase system efficiency and minimize optical losses, including draft surface shading and corner rounding losses, are explored. A CPV module, including the spectrum splitting solar concentrator and five PV cells of different bandgaps, is proposed. This spectrum splitting CPV system has a calculated aggregate cell conversion efficiency that exceeds 45%, has the potential to be mass produced, and meets the need for a high efficiency low cost solar energy conversion system.

  5. Achieving High Rates and High Uniformity in Copper Chemical Mechanical Polishing

    NASA Astrophysics Data System (ADS)

    Nolan, Lucy Marjorie

    The chemical mechanical polishing of Copper (Cu-CMP) is a complex and poorly understood process. Despite this, it is widely used throughout the semiconductor and microelectronics industries, and makes up a significant portion of wafer processing costs. In these contexts, desirable polishing outcomes such as a high rate of removal from the copper surface, and high removal rate uniformity, are achieved largely by trial-and-error. In this study, the same outcomes are pursued through a systematic investigation of polishing lubrication characteristics and abrasive and oxidiser concentrations in the polishing slurry. A strong link between lubrication characteristics, quantified by the dimensionless Sommerfield number, and the uniformity of polishing is demonstrated. A mechanism for the observed relationship is proposed, based on an adaptation of hydrodynamic lubrication theory. The overall rate of removal is maximized by polishing in a slurry containing oxidiser and abrasives in a synergistic ratio. Polishing away from this ratio has additional effects on the overall quality of the surface produced. Transport of slurry across the polishing pad is investigated by using tracers; the results demonstrate that slurry usage can be reduced in many circumstances with no impact on overall polishing outcomes, reducing overall processing costs. These findings are combined to design a polishing process, with good results.

  6. Studies of basic mechanisms in high pressure gases: Applications to high efficiency high power lasers

    NASA Technical Reports Server (NTRS)

    Verdeyen, J. T.; Cherrington, B. E.; Leslie, S. G.; Millar, W. S.; Edwards, B. E.

    1976-01-01

    A high power pulsed dye laser was used to optically excite high pressure cesium-xenon mixtures and the resulting measurements are presented. A microwave discharge in rubidium at relatively high xenon pressure was achieved. Preliminary studies of cadium-rare gas mixtures are discussed and a detailed description of the entire experimental apparatus is given.

  7. New York State Superintendents and Board Presidents Attitudes on Superintendent Responsibilities in High-Achieving and Low-Achieving School Districts

    ERIC Educational Resources Information Center

    Murphy, Matthew J.

    2009-01-01

    The purpose of this study is to determine the perceptions of New York State superintendents and board presidents in high-achieving and low-achieving school districts on the six superintendent leadership responsibilities identified by Waters and Marzano (2006) and their relationship to improving student achievement: (1) creating research-relevant…

  8. Small molecule semiconductors for high-efficiency organic photovoltaics.

    PubMed

    Lin, Yuze; Li, Yongfang; Zhan, Xiaowei

    2012-06-07

    Organic photovoltaic cells (OPVs) are a promising cost-effective alternative to silicon-based solar cells, and possess light-weight, low-cost, and flexibility advantages. Significant progress has been achieved in the development of novel photovoltaic materials and device structures in the last decade. Nowadays small molecular semiconductors for OPVs have attracted considerable attention, due to their advantages over their polymer counterparts, including well-defined molecular structure, definite molecular weight, and high purity without batch to batch variations. The highest power conversion efficiencies of OPVs based on small molecular donor/fullerene acceptors or polymeric donor/fullerene acceptors are up to 6.7% and 8.3%, respectively, and meanwhile nonfullerene acceptors have also exhibited some promising results. In this review we summarize the developments in small molecular donors, acceptors (fullerene derivatives and nonfullerene molecules), and donor-acceptor dyad systems for high-performance multilayer, bulk heterojunction, and single-component OPVs. We focus on correlations of molecular chemical structures with properties, such as absorption, energy levels, charge mobilities, and photovoltaic performances. This structure-property relationship analysis may guide rational structural design and evaluation of photovoltaic materials (253 references).

  9. Highly efficient transduction of primary adult CNS and PNS neurons

    PubMed Central

    Levin, Evgeny; Diekmann, Heike; Fischer, Dietmar

    2016-01-01

    Delivery and expression of recombinant genes, a key methodology for many applications in biological research, remains a challenge especially for mature neurons. Here, we report easy, highly efficient and well tolerated transduction of adult peripheral and central neuronal populations of diverse species in culture using VSV-G pseudo-typed, recombinant baculovirus (BacMam). Transduction rates of up to 80% were reliably achieved at high multiplicity of infection without apparent neuro-cytopathic effects. Neurons could be transduced either shortly after plating or after several days in culture. Co-incubation with two different baculoviruses attained near complete co-localization of fluorescent protein expression, indicating multigene delivery. Finally, evidence for functional protein expression is provided by means of cre-mediated genetic recombination and neurite outgrowth assays. Recombinant protein was already detected within hours after transduction, thereby enabling functional readouts even in relatively short-lived neuronal cultures. Altogether, these results substantiate the usefulness of baculovirus-mediated transduction of mature neurons for future research in neuroscience. PMID:27958330

  10. 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.

  11. Highly efficient frequency conversion with bandwidth compression of quantum light

    PubMed Central

    Allgaier, Markus; Ansari, Vahid; Sansoni, Linda; Eigner, Christof; Quiring, Viktor; Ricken, Raimund; Harder, Georg; Brecht, Benjamin; Silberhorn, Christine

    2017-01-01

    Hybrid quantum networks rely on efficient interfacing of dissimilar quantum nodes, as elements based on parametric downconversion sources, quantum dots, colour centres or atoms are fundamentally different in their frequencies and bandwidths. Although pulse manipulation has been demonstrated in very different systems, to date no interface exists that provides both an efficient bandwidth compression and a substantial frequency translation at the same time. Here we demonstrate an engineered sum-frequency-conversion process in lithium niobate that achieves both goals. We convert pure photons at telecom wavelengths to the visible range while compressing the bandwidth by a factor of 7.47 under preservation of non-classical photon-number statistics. We achieve internal conversion efficiencies of 61.5%, significantly outperforming spectral filtering for bandwidth compression. Our system thus makes the connection between previously incompatible quantum systems as a step towards usable quantum networks. PMID:28134242

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

    NASA Technical Reports Server (NTRS)

    Meier, D. L.

    1986-01-01

    Achievement of higher efficiency cells by directing efforts toward identifying carrier loss mechanisms; design of cell structures; and development of processing techniques are described. Use of techniques such as deep-level transient spectroscopy (DLTS), laser-beam-induced current (LBIC), and transmission electron microscopy (TEM) indicated that dislocations in web material rather than twin planes were primarily responsible for limiting diffusion lengths in the web. Lifetimes and cell efficiencies can be improved from 19 to 120 microns, and 8 to 10.3% (no AR), respectively, by implanting hydrogen at 1500 eV and a beam current density of 2.0 mA/sq cm. Some of the processing improvements included use of a double-layer AR coating (ZnS and MgF2) and an addition of an aluminum back surface reflectors. Cells of more than 16% efficiency were achieved.

  13. Highly efficient frequency conversion with bandwidth compression of quantum light

    NASA Astrophysics Data System (ADS)

    Allgaier, Markus; Ansari, Vahid; Sansoni, Linda; Eigner, Christof; Quiring, Viktor; Ricken, Raimund; Harder, Georg; Brecht, Benjamin; Silberhorn, Christine

    2017-01-01

    Hybrid quantum networks rely on efficient interfacing of dissimilar quantum nodes, as elements based on parametric downconversion sources, quantum dots, colour centres or atoms are fundamentally different in their frequencies and bandwidths. Although pulse manipulation has been demonstrated in very different systems, to date no interface exists that provides both an efficient bandwidth compression and a substantial frequency translation at the same time. Here we demonstrate an engineered sum-frequency-conversion process in lithium niobate that achieves both goals. We convert pure photons at telecom wavelengths to the visible range while compressing the bandwidth by a factor of 7.47 under preservation of non-classical photon-number statistics. We achieve internal conversion efficiencies of 61.5%, significantly outperforming spectral filtering for bandwidth compression. Our system thus makes the connection between previously incompatible quantum systems as a step towards usable quantum networks.

  14. New III-V cell design approaches for very high efficiency

    SciTech Connect

    Lundstrom, M.S.; Melloch, M.R.; Lush, G.B.; O'Bradovich, G.J.; Young, M.P. )

    1993-01-01

    This report describes progress during the first year of a three-year project. The objective of the research is to examine new design approaches for achieving very high conversion efficiencies. The program is divided into two areas. The first centers on exploring new thin-film approaches specifically designed for III-V semiconductors. The second area centers on exploring design approaches for achieving high conversion efficiencies without requiring extremely high quality material. Research activities consisted of an experimental study of minority carrier recombination in n-type, metal-organic chemical vapor deposition (MOCVD)-deposited GaAs, an assessment of the minority carrier lifetimes in n-GaAs grown by molecular beam epitaxy, and developing a high-efficiency cell fabrication process.

  15. High density GaN/AlN quantum dots for deep UV LED with high quantum efficiency and temperature stability

    PubMed Central

    Yang, Weihuang; Li, Jinchai; Zhang, Yong; Huang, Po-Kai; Lu, Tien-Chang; Kuo, Hao-Chung; Li, Shuping; Yang, Xu; Chen, Hangyang; Liu, Dayi; Kang, Junyong

    2014-01-01

    High internal efficiency and high temperature stability ultraviolet (UV) light-emitting diodes (LEDs) at 308 nm were achieved using high density (2.5 × 109 cm−2) GaN/AlN quantum dots (QDs) grown by MOVPE. Photoluminescence shows the characteristic behaviors of QDs: nearly constant linewidth and emission energy, and linear dependence of the intensity with varying excitation power. More significantly, the radiative recombination was found to dominant from 15 to 300 K, with a high internal quantum efficiency of 62% even at room temperature. PMID:24898569

  16. 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.

  17. Workshop Summary Proceedings Document: G7 Alliance on Resource Efficiency: U.S.-hosted Workshop on the Use of Life Cycle Concepts in Supply Chain Management to Achieve Resource Efficiency

    EPA Pesticide Factsheets

    This proceedings document summarizes prepared remarks, presentations and discussions from the G7 Alliance on Resource Efficiency: U.S.-hosted Workshop on the Use of Life Cycle Concepts in Supply Chain Management to Achieve Resource Efficiency.

  18. Understanding and Reversing Underachievement, Low Achievement, and Achievement Gaps among High-Ability African American Males in Urban School Contexts

    ERIC Educational Resources Information Center

    Ford, Donna Y.; Moore, James L., III

    2013-01-01

    This article focuses on the achievement gap, with attention devoted to underachievement and low achievement among African American males in urban school contexts. More specifically, the article explains problems and issues facing or confronting these Black male students in urban education settings. A central part of this discussion is grounded in…

  19. Gender and High School Chemistry: Student Perceptions on Achievement in a Selective Setting

    ERIC Educational Resources Information Center

    Cousins, Andrew; Mills, Martin

    2015-01-01

    This paper reports on research undertaken in a middle-class Australian school. The focus of the research was on the relationship between gender and students' engagement with high school chemistry. Achievement data from many OECD [Organisation for Economic Co-operation and Development] countries suggest that middle-class girls are achieving equally…

  20. Achievement Motivation in High School: Contrasting Theoretical Models in the Classroom.

    ERIC Educational Resources Information Center

    Garcia-Celay, I. Montero; Tapia, J. Alonso

    1992-01-01

    Three models of achievement motivation in the classroom are contrasted. Results with 155 high school students suggest that the model of C. S. Dweck and E. S. Elliott offers a better explanation of the relationships among achievement motivation, attributions, emotional reactions, expectancies, and performance than do the other models. (SLD)