Sample records for photoelectrochemical systems final

  1. Development & Optimization of Materials and Processes for a Cost Effective Photoelectrochemical Hydrogen Production System. Final report

    SciTech Connect

    McFarland, Eric W


    The overall project objective was to apply high throughput experimentation and combinatorial methods together with novel syntheses to discover and optimize efficient, practical, and economically sustainable materials for photoelectrochemical production of bulk hydrogen from water. Automated electrochemical synthesis and photoelectrochemical screening systems were designed and constructed and used to study a variety of new photoelectrocatalytic materials. We evaluated photocatalytic performance in the dark and under illumination with or without applied bias in a high-throughput manner and did detailed evaluation on many materials. Significant attention was given to -Fe2O3 based semiconductor materials and thin films with different dopants were synthesized by co-electrodeposition techniques. Approximately 30 dopants including Al, Zn, Cu, Ni, Co, Cr, Mo, Ti, Pt, etc. were investigated. Hematite thin films doped with Al, Ti, Pt, Cr, and Mo exhibited significant improvements in efficiency for photoelectrochemical water splitting compared with undoped hematite. In several cases we collaborated with theorists who used density functional theory to help explain performance trends and suggest new materials. The best materials were investigated in detail by X-ray diffraction (XRD), scanning electron microscopy (SEM), ultraviolet-visual spectroscopy (UV-Vis), X-ray photoelectron spectroscopy (XPS). The photoelectrocatalytic performance of the thin films was evaluated and their incident photon

  2. Photoelectrochemical Hydrogen Production - Final Report

    SciTech Connect

    Miller, E.L.; Marsen, B.; Paluselli, D.; Rocheleau, R.


    The scope of this photoelectrochemical hydrogen research project is defined by multijunction photoelectrode concepts for solar-powered water splitting, with the goal of efficient, stable, and economic operation. From an initial selection of several planar photoelectrode designs, the Hybrid Photoelectrode (HPE) has been identified as the most promising candidate technology. This photoelectrode consists of a photoelectrochemical (PEC) junction and a solid-state photovoltaic (PV) junction. Immersed in aqueous electrolyte and exposed to sunlight, these two junctions provide the necessary voltage to split water into hydrogen and oxygen gas. The efficiency of the conversion process is determined by the performance of the PEC- and the PV-junctions and on their spectral match. Based on their stability and cost effectiveness, iron oxide (Fe2O3) and tungsten oxide (WO3) films have been studied and developed as candidate semiconductor materials for the PEC junction (photoanode). High-temperature synthesis methods, as reported for some high-performance metal oxides, have been found incompatible with multijunction device fabrication. A low-temperature reactive sputtering process has been developed instead. In the parameter space investigated so far, the optoelectronic properties of WO3 films were superior to those of Fe2O3 films, which showed high recombination of photo-generated carriers. For the PV-junction, amorphous-silicon-based multijunction devices have been studied. Tandem junctions were preferred over triple junctions for better stability and spectral matching with the PEC junction. Based on a tandem a-SiGe/a-SiGe device and a tungsten trioxide film, a prototype hybrid photoelectrode has been demonstrated at 0.7% solar-to-hydrogen (STH) conversion efficiency. The PEC junction performance has been identified as the most critical element for higher-efficiency devices. Research into sputter-deposited tungsten trioxide films has yielded samples with higher photocurrents of

  3. Photoelectrochemical based direct conversion systems

    SciTech Connect

    Kocha, S.; Arent, D.; Peterson, M.


    The goal of this research is to develop a stable, cost effective, photoelectrochemical based system that will split water upon illumination, producing hydrogen and oxygen directly, using sunlight as the only energy input. This type of direct conversion system combines a photovoltaic material and an electrolyzer into a single monolithic device. We report on our studies of two multifunction multiphoton photoelectrochemical devices, one based on the ternary semiconductor gallium indium phosphide, (GaInP{sub 2}), and the other one based on amorphous silicon carbide. We also report on our studies of the solid state surface treatment of GaInP{sub 2} as well as our continuing effort to develop synthetic techniques for the attachment of transition metal complexes to the surface of semiconductor electrodes. All our surface studies are directed at controlling the interface energetics and forming stable catalytic surfaces.

  4. Photoelectrochemical Water Systems for H2 Production (Presentation)

    SciTech Connect

    Turner, J. A.; Deutsch, T.; Head, J.; Vallett, P.


    This Photoelectrochemical Water Systems for Hydrogen Production presentation by the National Renewable Energy Laboratory's John Turner was given at the DOE Hydrogen Program's 2007 Annual Merit Review.

  5. Integrated photoelectrochemical cell and system having a liquid electrolyte


    Deng, Xunming; Xu, Liwei


    An integrated photoelectrochemical (PEC) cell generates hydrogen and oxygen from water while being illuminated with radiation. The PEC cell employs a liquid electrolyte, a multi-junction photovoltaic electrode, and a thin ion-exchange membrane. A PEC system and a method of making such PEC cell and PEC system are also disclosed.

  6. Photoelectrochemical based direct conversion systems for hydrogen production

    SciTech Connect

    Khaselev, O.; Bansal, A.; Kocha, S.; Turner, J.A.


    With an eye towards developing a photoelectrochemical system for hydrogen production using sunlight as the only energy input, two types of systems were studied, both involving multijunction devices. One set of cells consisted of a-Si triple junctions and the other a GaInP{sub 2}/GaAs tandem cell combination. Additional investigations were carried out on semiconductor surface modifications to move semiconductor band edges to more favorable energetic positions.

  7. Photoelectrochemical based direct conversion systems for hydrogen production

    SciTech Connect

    Kocha, S.; Peterson, M.; Arent, D.


    Photon driven, direct conversion systems consist of a light absorber and a water splitting catalyst as a monolithic system; water is split directly upon illumination. This one-step process eliminates the need to generate electricity externally and subsequently feed it to an electrolyzer. These configurations require only the piping necessary for transport of hydrogen to an external storage system or gas pipeline. This work is focused on multiphoton photoelectrochemical devices for production of hydrogen directly using sunlight and water. Two types of multijunction cells, one consisting of a-Si triple junctions and the other GaInP{sub 2}/GaAs homojunctions, were studied for the photoelectrochemical decomposition of water into hydrogen and oxygen from an aqueous electrolyte solution. To catalyze the water decomposition process, the illuminated surface of the device was modified either by addition of platinum colloids or by coating with ruthenium dioxide. These colloids have been characterized by gel electrophoresis.

  8. Novel catalysts and photoelectrochemical system for solar fuel production

    NASA Astrophysics Data System (ADS)

    Zhang, Yan

    Solar fuel production from abundant raw chemicals such as CO2 and water is highly desired as a clean renewable energy solution for the future. Developing photoelectrochemical cells is viewed as a promising approach to realize this energy conversion and storage process. Efficient and robust oxygen evolution catalyst made from non-precious materials remains a major challenge for such a system. This thesis basically consists of three parts of work, including studies on enhancing the photocatalytic oxygen evolution activity of cobalt-based spinel nanoparticles by manganese3+ substitution, in situ formation of cobalt oxide nanocubanes as highly active catalyst for photocatalytic oxygen evolution reaction, and development of a photoanode-driven photoelectrochemical cell for CO2 reduction with water. The first part of this thesis work devotes efforts in the development and study on cobalt and other transition metal oxide based oxygen evolution catalyst. Photocatalytic oxygen evolution is a critical step for solar fuel production from abundant sources. It poses a significant challenge because it requires an efficient catalyst to bridge the one-electron photon capture process with the four-electron oxygen reaction. Among all the metal oxides, Co3O4 spinel exhibits a high activity as an oxygen evolution catalyst. The results of this work demonstrate that the photocatalytic oxygen evolution activity of Co3O4 spinel can be further enhanced by substituting Co with Mn in the spinel structure. Using a facile hydrothermal approach, Co3O4 spinel nanoparticles as well as Mn-substituted and Ni-substituted Co3O4 spinel nanoparticles with a typical particle size of 5-7 nm were successfully synthesized. The morphology and crystal structures of the as-synthesized nanoparticle catalysts have been carefully examined using various structural characterization techniques, including powder x-ray diffraction (PXRD), transmission electron microscope (TEM), gas adsorption, and x-ray absorption

  9. Design of two electrode system for detection of antioxidant capacity with photoelectrochemical platform.


    Han, Dongxue; Ma, Weiguang; Wang, Lingnan; Ni, Shuang; Zhang, Nan; Wang, Wei; Dong, Xiandui; Niu, Li


    Recently, a flow photoelectrochemical cell has been first developed and applied to assay global antioxidant capacity in our group. Yet, shortcomings of liquid reference electrode such as sample contaminations from the leaking of the reference solution, mechanically fragile, temperature and light sensitivity, etc. are significant restrictions for integration and miniaturization of photoelectrochemical sensing instruments, which have greatly limited their practical applications. Bearing these problems, in this work a novel two electrode flow photoelectron-chemical system (two-EPCS) has been developed for detection of antioxidant capacity. It is noteworthy that the electrochemical modulation-free mode (detection at the potential of 0.0V) is performed, which has greatly simplified the analysis process and will result in significant simplifications of the instrument integrations. During the sample analysis, both standard antioxidants and commercial beverages were detected. Results evaluated from the two-EPCS are well agreed with those of the traditional three-EPCS at low potentials. By unloading of the reference electrode, it is of great convenience to design a novel photoelectrochemical microfluidic chip based on the two-EPCS, which has also been successfully applied for antioxidant capacity assay. It is satisfactory that comparable detection concentration range and sensitivity were accomplished by applying the microfluidic chip technique. Moreover, the two-EPCS is verified to be a universal platform which does not depend on selected optoelectronic materials but pervasive for general photocatalysts. Such a two-EPCS should be considered as a feasible alternative to the three-EPCS, which will become a promising candidate for industrial and commercial photoelectrochemical sensing instrument integrations in the future. PMID:26363494

  10. Metal-based anode for high performance bioelectrochemical systems through photo-electrochemical interaction

    NASA Astrophysics Data System (ADS)

    Liang, Yuxiang; Feng, Huajun; Shen, Dongsheng; Long, Yuyang; Li, Na; Zhou, Yuyang; Ying, Xianbin; Gu, Yuan; Wang, Yanfeng


    This paper introduces a novel composite anode that uses light to enhance current generation and accelerate biofilm formation in bioelectrochemical systems. The composite anode is composed of 316L stainless steel substrate and a nanostructured α-Fe2O3 photocatalyst (PSS). The electrode properties, current generation, and biofilm properties of the anode are investigated. In terms of photocurrent, the optimal deposition and heat-treatment times are found to be 30 min and 2 min, respectively, which result in a maximum photocurrent of 0.6 A m-2. The start-up time of the PSS is 1.2 days and the maximum current density is 2.8 A m-2, twice and 25 times that of unmodified anode, respectively. The current density of the PSS remains stable during 20 days of illumination. Confocal laser scanning microscope images show that the PSS could benefit biofilm formation, while electrochemical impedance spectroscopy indicates that the PSS reduce the charge-transfer resistance of the anode. Our findings show that photo-electrochemical interaction is a promising way to enhance the biocompatibility of metal anodes for bioelectrochemical systems.

  11. Zinc oxide nanoparticles/glucose oxidase photoelectrochemical system for the fabrication of biosensor.


    Ren, Xiangling; Chen, Dong; Meng, Xianwei; Tang, Fangqiong; Hou, Xianquan; Han, Dong; Zhang, Lin


    Nanosized semiconductor crystals can increase efficiency of photochemical reactions and greatly improve the catalytic activity of enzymes to generate novel photoelectrochemical systems. In this work, glucose oxidase (GOx)/zinc oxide (ZnO) is selected as a model system to assess the photovoltaic effect of semiconductor nanoparticles on the enzyme electrode. UV-spectrum and circular dichroism (CD) results show that the structure of GOx is preserved after conjugation with ZnO nanoparticles. The current response of the enzyme electrode containing ZnO nanoparticles increases from 0.82 to 21 microA cm(-2) in the solution of 10 mM beta-D-glucose. Furthermore, after irradiating the enzyme electrode with UV light for 2 h, the current response can be increased nearly 30% and the detection limit can be lowered about two orders compared with the catalytic reactions in the dark, which indicate that a technique to fabricate a novel photocontrolled enzyme-based biosensor may be developed. PMID:19394953

  12. Photoelectrochemical cell


    Rauh, R. David; Boudreau, Robert A.


    A photoelectrochemical cell comprising a sealed container having a light-transmitting window for admitting light into the container across a light-admitting plane, an electrolyte in the container, a photoelectrode in the container having a light-absorbing surface arranged to receive light from the window and in contact with the electrolyte, the surface having a plurality of spaced portions oblique to the plane, each portion having dimensions at least an order of magnitude larger than the maximum wavelength of incident sunlight, the total surface area of the surface being larger than the area of the plane bounded by the container, and a counter electrode in the container in contact with the electrolyte.

  13. Nanocomposite Photoelectrochemical Cells

    NASA Technical Reports Server (NTRS)

    Narayan, Sri R.; Kindler, Andrew; Whitacre, Jay F.


    Improved, solid-state photoelectrochemical cells for converting solar radiation to electricity have been proposed. (In general, photoelectrochemical cells convert incident light to electricity through electrochemical reactions.) It is predicted that in comparison with state-of-the-art photoelectrochemical cells, these cells will be found to operate with greater solar-to-electric energy-conversion efficiencies.

  14. Effect of inserted Si p-n junction on GaN-based photo-electrochemical CO2 conversion system

    NASA Astrophysics Data System (ADS)

    Yotsuhashi, Satoshi; Deguchi, Masahiro; Yamada, Yuka; Ohkawa, Kazuhiro


    We report on significantly improved GaN-based photo-electrochemical CO2 reduction system by inserting Si p-n junction. The device is introduced so as to raise the cathode potential which changes the reaction products qualitatively. It is discussed that the balance between cathode and anode reactions is essential to take the advantage of introduced device. We succeed in stoichiometric evaluation of oxygen evolution on the surface of GaN photo-electrode. When the reaction condition is optimized, we can realize the raised cathode potential, in which the chief reaction product of CO2 reduction changes from formic acid to hydrocarbons, such as methane (CH4) and ethylene (C2H4).

  15. Interplay of light transmission and catalytic exchange current in photoelectrochemical systems

    NASA Astrophysics Data System (ADS)

    Fountaine, Katherine T.; Lewerenz, Hans J.; Atwater, Harry A.


    We develop an analytic current-voltage expression for a variable junction photoelectrochemical (PEC) cell and use it to investigate and illustrate the influence of the optical and electrical properties of catalysts on the optoelectronic performance of PEC devices. Specifically, the model enables a simple, yet accurate accounting of nanostructured catalyst optical and electrical properties through incorporation of an optical transmission factor and active catalytic area factor. We demonstrate the utility of this model via the output power characteristics of an exemplary dual tandem solar cell with indium gallium phosphide and indium gallium arsenide absorbers with varying rhodium catalyst nanoparticle loading. The approach highlights the importance of considering interactions between independently optimized components for optimal PEC device design.

  16. Interplay of light transmission and catalytic exchange current in photoelectrochemical systems

    SciTech Connect

    Fountaine, Katherine T.; Lewerenz, Hans J.; Atwater, Harry A.


    We develop an analytic current-voltage expression for a variable junction photoelectrochemical (PEC) cell and use it to investigate and illustrate the influence of the optical and electrical properties of catalysts on the optoelectronic performance of PEC devices. Specifically, the model enables a simple, yet accurate accounting of nanostructured catalyst optical and electrical properties through incorporation of an optical transmission factor and active catalytic area factor. We demonstrate the utility of this model via the output power characteristics of an exemplary dual tandem solar cell with indium gallium phosphide and indium gallium arsenide absorbers with varying rhodium catalyst nanoparticle loading. The approach highlights the importance of considering interactions between independently optimized components for optimal PEC device design.

  17. A study on the effect of low energy ion beam irradiation on Au/TiO2 system for its application in photoelectrochemical splitting of water

    NASA Astrophysics Data System (ADS)

    Verma, Anuradha; Srivastav, Anupam; Sharma, Dipika; Banerjee, Anamika; Sharma, Shailja; Satsangi, Vibha Rani; Shrivastav, Rohit; Avasthi, Devesh Kumar; Dass, Sahab


    Nanostructured TiO2 thin films were deposited on indium tin oxide (ITO) substrate via sol-gel technique and were modified by plasmonic Au layer. The plasmonic Au modified TiO2 (Au/TiO2) thin films were then irradiated with 500 keV Ar2+ ion beam at different ion fluences viz. 1 × 1016, 3 × 1016 and 1 × 1017 to study the effect of nuclear energy deposition on the morphology, crystallinity, band gap, surface plasmon resonance (SPR) peak exhibited by Au particles and photoelectrochemical properties of the system. Prepared thin films were characterized by X-ray diffractometry (XRD), scanning electron microscopy (SEM), Rutherford backscattering spectrometry (RBS) measurements and UV-visible spectroscopy. The photoelectrochemical measurements revealed that both Au/TiO2 and Au/TiO2 thin film irradiated at 1 × 1016 fluence exhibits enhanced photoelectrochemical response in comparison to pristine TiO2. The film irradiated at 1 × 1016 fluence offered maximum applied bias photon-to-current efficiency (ABPE) and shows 6 times increment in photocurrent density which was attributed to more negative flat band potential, maximum decrease in band gap, high open circuit voltage (Voc) and reduced charge transfer resistance.

  18. Comparison of photoelectrochemical water oxidation activity of a synthetic photocatalyst system with photosystem II.


    Lai, Yi-Hsuan; Kato, Masaru; Mersch, Dirk; Reisner, Erwin


    This discussion describes a direct comparison of photoelectrochemical (PEC) water oxidation activity between a photosystem II (PSII)-functionalised photoanode and a synthetic nanocomposite photoanode. The semi-biological photoanode is composed of PSII from the thermophilic cyanobacterium Thermosynechococcus elongatus on a mesoporous indium tin oxide electrode (mesoITO|PSII). PSII embeds all of the required functionalities for light absorption, charge separation and water oxidation and ITO serves solely as the electron collector. The synthetic photoanode consists of a TiO(2) and NiO(x) coated nanosheet-structured WO(3) electrode (nanoWO(3)|TiO(2)|NiO(x)). The composite structure of the synthetic electrode allows mimicry of the functional key features in PSII: visible light is absorbed by WO(3), TiO(2) serves as a protection and charge separation layer and NiO(x) serves as the water oxidation electrocatalyst. MesoITO|PSII uses low energy red light, whereas nanoWO(3)|TiO(2)|NiO(x) requires high energy photons of blue-end visible and UV regions to oxidise water. The electrodes have a comparable onset potential at approximately 0.6 V vs. reversible hydrogen electrode (RHE). MesoITO|PSII reaches its saturation photocurrent at 0.84 V vs. RHE, whereas nanoWO(3)|TiO(2)NiO(x) requires more than 1.34 V vs. RHE. This suggests that mesoITO|PSII suffers from fewer limitations from charge recombination and slow water oxidation catalysis than the synthetic electrode. MesoITO|PSII displays a higher 'per active' site activity, but is less photostable and displays a much lower photocurrent per geometrical surface area and incident photon to current conversion efficiency (IPCE) than nanoWO(3)|TiO(2)|NiO(x_. PMID:25434986

  19. Photoelectrochemical hydrogen production

    SciTech Connect

    Rocheleau, R.; Misra, A.; Miller, E.


    A significant component of the US DOE Hydrogen Program is the development of a practical technology for the direct production of hydrogen using a renewable source of energy. High efficiency photoelectrochemical systems to produce hydrogen directly from water using sunlight as the energy source represent one of the technologies identified by DOE to meet this mission. Reactor modeling and experiments conducted at UH provide strong evidence that direct solar-to-hydrogen conversion efficiency greater than 10% can be expected using photoelectrodes fabricated from low-cost, multijunction (MJ) amorphous silicon solar cells. Solar-to-hydrogen conversion efficiencies as high as 7.8% have been achieved using a 10.3% efficient MJ amorphous silicon solar cell. Higher efficiency can be expected with the use of higher efficiency solar cells, further improvement of the thin film oxidation and reduction catalysts, and optimization of the solar cell for hydrogen production rather than electricity production. Hydrogen and oxygen catalysts developed under this project are very stable, exhibiting no measurable degradation in KOH after over 13,000 hours of operation. Additional research is needed to fully optimize the transparent, conducting coatings which will be needed for large area integrated arrays. To date, the best protection has been afforded by wide bandgap amorphous silicon carbide films.

  20. Photoelectrochemical hydrogen production

    SciTech Connect

    Rocheleau, R.E.; Miller, E.; Zhang, Z.


    The large-scale production of hydrogen utilizing energy provided by a renewable source to split water is one of the most ambitious long-term goals of the U.S. Department of Energy`s Hydrogen Program. Photoelectrochemical devices-direct photoconversion systems utilizing a photovoltaic-type structure coated with water-splitting catalysts-represent a promising option to meet this goal. Direct solar-to-chemical conversion efficiencies greater than 7% and photoelectrode lifetimes of up to 30 hours in 1 molar KOH have been demonstrated in our laboratory using low-cost, amorphous-silicon-based photoelectrodes. Loss analysis models indicate that the DOE`s goal of 10% solar-to-chemical conversion can be met with amorphous-silicon-based structures optimized for hydrogen production. In this report, we describe recent progress in the development of thin-film catalytic/protective coatings, improvements in photoelectrode efficiency and stability, and designs for higher efficiency and greater stability.

  1. Photoelectrochemical Solar Cells.

    ERIC Educational Resources Information Center

    McDevitt, John T.


    This introduction to photoelectrochemical (PEC) cells reviews topics pertaining to solar energy conversion and demonstrates the ease with which a working PEC cell can be prepared with n-type silicon as the photoanode and a platinum counter electrode (both immersed in ethanolic ferrocene/ferricenium solutions). Experiments using the cell are…

  2. Calibration Systems Final Report

    SciTech Connect

    Myers, Tanya L.; Broocks, Bryan T.; Phillips, Mark C.


    The Calibration Systems project at Pacific Northwest National Laboratory (PNNL) is aimed towards developing and demonstrating compact Quantum Cascade (QC) laser-based calibration systems for infrared imaging systems. These on-board systems will improve the calibration technology for passive sensors, which enable stand-off detection for the proliferation or use of weapons of mass destruction, by replacing on-board blackbodies with QC laser-based systems. This alternative technology can minimize the impact on instrument size and weight while improving the quality of instruments for a variety of missions. The potential of replacing flight blackbodies is made feasible by the high output, stability, and repeatability of the QC laser spectral radiance.

  3. Final focus system for TLC

    SciTech Connect

    Oide, K.


    A limit of the chromaticity correction for the final focus system of a TeV Linear Collider (TLC) is investigated. As the result, it becomes possible to increase the aperture of the final doublet with a small increase of the horizontal US function. The new optics design uses a final doublet of 0.5 mm half-aperture and 1.4 T pole-tip field. The length of the system is reduced from 400 m to 200 m by several optics changes. Tolerances for various machine errors with this optics are also studied. 5 refs., 7 figs., 2 tabs.

  4. New architectures for integrated photoelectrochemical systems. Final report, Sept. 1998 - Dec. 2001

    SciTech Connect

    Fox, Marye Anne


    During the three year grant period, significant progress has been made toward the accomplishment of each of the goals outlined in the original proposal. The budget proposed for the project was also expended fully, as originally projected. In accord with these objectives, we have prepared an array of new macromolecules and supramolecular aggregates in which a light-sensitive organic group initiates long range photoinduced electron transfer in this designed heterogeneous environment. In doing so, we have developed several new synthetic methodologies for accurate spatial definition of these polymeric arrays on a nanometer to micrometer scale. We have used these integrated materials to define the photophysical principles that control vectorial energy and electron migration over distances that are large compared with the dimensions of most small molecules. By attaching these same molecules to the surface of a metal or semiconductor electrode, we have obtained chemically modified surfaces that function as efficient vehicles for conversion of incident photons to chemical or electrical energy. Thus, we have investigated: (1) the synthesis and characterization of new polymeric and supramolecular arrays for directional electron transfer; (2) new techniques for optical imaging in self-assembled monolayers on metals (mostly gold); and (3) fundamental principles that govern long range electronic coupling along rigid molecular backbones.

  5. Photoelectrochemical cell/dye-sensitized solar cell tandem water splitting systems with transparent and vertically aligned quantum dot sensitized TiO2 nanorod arrays

    NASA Astrophysics Data System (ADS)

    Shin, Kahee; Yoo, Ji-Beom; Park, Jong Hyeok


    The present work reports fabrication of vertically aligned CdS sensitized TiO2 nanorod arrays grown on transparent conducting oxide substrate with high transparency as a photoanode in photoelectrochemical cell for water splitting. To realize an unassisted water splitting system, the photoanode and dye-sensitized solar cell tandem structures are tried and their electrochemical behaviors are also investigated. The hydrothermally grown TiO2 nanorod arrays followed by CdS nanoparticle decoration can improve the light absorption of long wavelength light resulting in increased photocurrent density. Two different techniques (electrodeposition and spray pyrolysis deposition) of CdS nanoparticle sensitization are carried out and their water splitting behaviors in the tandem cell are compared.

  6. Photoelectrochemical Hydrogen Production

    SciTech Connect

    Hu, Jian


    The objectives of this project, covering two phases and an additional extension phase, were the development of thin film-based hybrid photovoltaic (PV)/photoelectrochemical (PEC) devices for solar-powered water splitting. The hybrid device, comprising a low-cost photoactive material integrated with amorphous silicon (a-Si:H or a-Si in short)-based solar cells as a driver, should be able to produce hydrogen with a 5% solar-to-hydrogen conversion efficiency (STH) and be durable for at least 500 hours. Three thin film material classes were studied and developed under this program: silicon-based compounds, copper chalcopyrite-based compounds, and metal oxides. With the silicon-based compounds, more specifically the amorphous silicon carbide (a-SiC), we achieved a STH efficiency of 3.7% when the photoelectrode was coupled to an a-Si tandem solar cell, and a STH efficiency of 6.1% when using a crystalline Si PV driver. The hybrid PV/a-SiC device tested under a current bias of -3~4 mA/cm{sup 2}, exhibited a durability of up to ~800 hours in 0.25 M H{sub 2}SO{sub 4} electrolyte. Other than the PV driver, the most critical element affecting the photocurrent (and hence the STH efficiency) of the hybrid PV/a-SiC device was the surface energetics at the a-SiC/electrolyte interface. Without surface modification, the photocurrent of the hybrid PEC device was ~1 mA/cm{sup 2} or lower due to a surface barrier that limits the extraction of photogenerated carriers. We conducted an extensive search for suitable surface modification techniques/materials, of which the deposition of low work function metal nanoparticles was the most successful. Metal nanoparticles of ruthenium (Ru), tungsten (W) or titanium (Ti) led to an anodic shift in the onset potential. We have also been able to develop hybrid devices of various configurations in a monolithic fashion and optimized the current matching via altering the energy bandgap and thickness of each constituent cell. As a result, the short

  7. Nanostructured semiconductor films for photocatalysis. Photoelectrochemical behavior of SnO{sub 2}/TiO{sub 2} composite systems and its role in photocatalytic degradation of a textile azo dye

    SciTech Connect

    Vinodgopal, K.; Bedja, I.; Kamat, P.V.


    Nanostructured semiconductor films of SnO{sub 2}, TiO{sub 2}, and SnO{sub 2}/TiO{sub 2} have been employed for electrochemically assisted photocatalytic degradation of a textile azo dye naphthol blue black (NBB). The degradation rate is significantly higher for SnO{sub 2}/TiO{sub 2} composite films than SnO{sub 2} and TiO{sub 2} films alone. An effort has been made to correlate the photoelectrochemical behavior of these films to the rate of photocatalytic degradation of NBB. The enhanced degradation rate of NBB using composite semiconductor films is attributed to increased charge separation in these systems. Photoelectrochemical and photocatalytic degradation experiments carried out in both nitrogen- and oxygen-saturated solutions with an externally applied electrochemical bias provide useful information in optimizing semiconductor concentrations in a composite film. 83 refs., 9 figs., 1 tab.

  8. (Wind electric systems). Final report

    SciTech Connect

    Sencenbaugh, J.R.


    This report details the results of a demonstration project, the design and testing of a low power, high reliability wind electric system for remote, stand-alone locations. The study consisted of two basic areas. An engineering redesign of a sucessful preproduction prototype to determine best material usage in castings and manufacturing time, in addition to evaluating performance vs cost tradeoffs in design. The second stage of the program covered actual field testing of the redesigned machine in remote areas. After field testing, the machine was to undertake a final redesign to correct any weak areas found during the field evaluation period. Three machines of this design were tested throughout various regions of the United States. These units were located in Nederland, Colorado, Whidbey Island, Washington and Fort Cronkite, San Francisco, CA. The results obtained from prolonged testing were both varied and valuable. A detailed structural analysis was done during the preliminary redesign and final design stages of this program. This report is organized in chronological order.

  9. Recent advances in semiconductors for photocatalytic and photoelectrochemical water splitting.


    Hisatomi, Takashi; Kubota, Jun; Domen, Kazunari


    Photocatalytic and photoelectrochemical water splitting under irradiation by sunlight has received much attention for production of renewable hydrogen from water on a large scale. Many challenges still remain in improving energy conversion efficiency, such as utilizing longer-wavelength photons for hydrogen production, enhancing the reaction efficiency at any given wavelength, and increasing the lifetime of the semiconductor materials. This introductory review covers the fundamental aspects of photocatalytic and photoelectrochemical water splitting. Controlling the semiconducting properties of photocatalysts and photoelectrode materials is the primary concern in developing materials for solar water splitting, because they determine how much photoexcitation occurs in a semiconductor under solar illumination and how many photoexcited carriers reach the surface where water splitting takes place. Given a specific semiconductor material, surface modifications are important not only to activate the semiconductor for water splitting but also to facilitate charge separation and to upgrade the stability of the material under photoexcitation. In addition, reducing resistance loss and forming p-n junction have a significant impact on the efficiency of photoelectrochemical water splitting. Correct evaluation of the photocatalytic and photoelectrochemical activity for water splitting is becoming more important in enabling an accurate comparison of a number of studies based on different systems. In the latter part, recent advances in the water splitting reaction under visible light will be presented with a focus on non-oxide semiconductor materials to give an overview of the various problems and solutions. PMID:24413305

  10. Solar energy conversion by chloroplast photoelectrochemical cells

    NASA Astrophysics Data System (ADS)

    Bhardwaj, R.; Pan, R. L.; Gross, E. L.


    A photoelectrochemical cell based on chloroplasts which generates large photovoltages and photocurrents from solar energy is presented. The cell contains broken Type C chloroplasts placed on a filter separating compartments containing an electron acceptor and electron donor with platinum electrodes in each. Photovoltages were observed across a load resistance of 3000 ohms with either flavin mononucleotide or anthroquinone 2-sulphonate as the electron acceptor and dichlorophenol indophenol as the donor, and persisted for 1-2 hr after the light was turned off. The powers and short circuit currents obtained in the chloroplast cells are nearly equal to those obtained in cells based on isolated photosystem I particles. Finally, an efficiency of 2.3% has been measured for the chloroplast contribution to the total power in flavin mononucleotide cells.


    SciTech Connect

    Philip Holmes


    This document is the final report on the work completed on DE-FG02-95ER25238 since the start of the second renewal period: Jan 1, 2001. It supplements the annual reports submitted in 2001 and 2002. In the renewal proposal I envisaged work in three main areas: Analytical and topological tools for studying flows and maps Low dimensional models of fluid flow Models of animal locomotion and I describe the progess made on each project.

  12. Photoelectrochemical reduction of carbon dioxide using Ge doped GaN nanowire photoanodes

    NASA Astrophysics Data System (ADS)

    Wang, Yichen; AlOtaibi, Bandar; Chowdhury, Faqrul A.; Fan, Shizhao; Kibria, Md G.; Li, Lu; Li, Chao-Jun; Mi, Zetian


    We report on the direct conversion of carbon dioxide (CO2) in a photoelectrochemical cell consisting of germanium doped gallium nitride nanowire anode and copper (Cu) cathode. Various products including methane (CH4), carbon monoxide (CO), and formic acid (HCOOH) were observed under light illumination. A Faradaic efficiency of ˜10% was measured for HCOOH. Furthermore, this photoelectrochemical system showed enhanced stability for 6 h CO2 reduction reaction on low cost, large area Si substrates.

  13. Sunlight-Driven Hydrogen Formation by Membrane-Supported Photoelectrochemical Water Splitting

    SciTech Connect

    Lewis, Nathan S.


    This report describes the significant advances in the development of the polymer-supported photoelectrochemical water-splitting system that was proposed under DOE grant number DE-FG02-05ER15754. We developed Si microwire-array photoelectrodes, demonstrated control over the material and light-absorption properties of the microwire-array photoelectrodes, developed inexpensive processes for synthesizing the arrays, and doped the arrays p-type for use as photocathodes. We also developed techniques for depositing metal-nanoparticle catalysts of the hydrogen-evolution reaction (HER) on the wire arrays, investigated the stability and catalytic performance of the nanoparticles, and demonstrated that Ni-Mo alloys are promising earth-abundant catalysts of the HER. We also developed methods that allow reuse of the single-crystalline Si substrates used for microwire growth and methods of embedding the microwire photocathodes in plastic to enable large-scale processing and deployment of the technology. Furthermore we developed techniques for controlling the structure of WO3 films, and demonstrated that structural control can improve the quantum yield of photoanodes. Thus, by the conclusion of this project, we demonstrated significant advances in the development of all components of a sunlight-driven membrane-supported photoelectrochemical water-splitting system. This final report provides descriptions of some of the scientific accomplishments that were achieved under the support of this project and also provides references to the peer-reviewed publications that resulted from this effort.

  14. Experimental lithium system. Final report

    SciTech Connect

    Kolowith, R.; Berg, J.D.; Miller, W.C.


    A full-scale mockup of the Fusion Materials Irradiation Test (FMIT) Facility lithium system was built at the Hanford Engineering Development Laboratory (HEDL). This isothermal mockup, called the Experimental Lithium System (ELS), was prototypic of FMIT, excluding the accelerator and dump heat exchanger. This 3.8 m/sup 3/ lithium test loop achieved over 16,000 hours of safe and reliable operation. An extensive test program demonstrated satisfactory performance of the system components, including the HEDL-supplied electromagnetic lithium pump, the lithium jet target, the purification and characterization hardware, as well as the auxiliary argon and vacuum systems. Experience with the test loop provided important information on system operation, performance, and reliability. This report presents a complete overview of the entire Experimental Lithium System test program and also includes a summary of such areas as instrumentation, coolant chemistry, vapor/aerosol transport, and corrosion.

  15. Inventory Systems Laboratory. Final Report.

    ERIC Educational Resources Information Center

    Naddor, Eliezer

    Four computer programs to aid students in understanding inventory systems, constructing mathematical inventory models, and developing optimal decision rules are presented. The program series allows a user to set input levels, simulates the behavior of major variables in inventory systems, and provides performance measures as output. Inventory…

  16. Systems Design Orientation. Final Report.

    ERIC Educational Resources Information Center

    Oklahoma State Dept. of Institutions, Social and Rehabilitation Services, Oklahoma City.

    A 40-hour course in systems design is described. The course was developed for presentation to non-data processing management personnel whose responsibilities include utilization of data processing services. All course material is included. (Author/JY)

  17. Final Barrier: Small System Compliance

    EPA Science Inventory

    This presentation will discuss the use of point-of-use (POU) technology for small drinking water systems. Information will be provided on the USEPA regulations that allow the use of POU for compliance and the technologies that are listed as SSCT for radium and arsenic. Listing o...

  18. Special Delivery Systems. Final Report.

    ERIC Educational Resources Information Center

    Molek, Carol

    The Special Delivery Systems project developed a curriculum for students with learning disabilities (LD) in an adult basic education program. The curriculum was designed to assist and motivate the students in the educational process. Fourteen students with LD were recruited and screened. The curriculum addressed varied learning styles combined…

  19. A Titanium-Doped SiOx Passivation Layer for Greatly Enhanced Performance of a Hematite-Based Photoelectrochemical System.


    Ahn, Hyo-Jin; Yoon, Ki-Yong; Kwak, Myung-Jun; Jang, Ji-Hyun


    This study introduces an in situ fabrication of nanoporous hematite with a Ti-doped SiOx passivation layer for a high-performance water-splitting system. The nanoporous hematite with a Ti-doped SiOx layer (Ti-(SiOx /np-Fe2 O3 )) has a photocurrent density of 2.44 mA cm(-2) at 1.23 VRHE and 3.70 mA cm(-2) at 1.50 VRHE . When a cobalt phosphate co-catalyst was applied to Ti-(SiOx /np-Fe2 O3 ), the photocurrent density reached 3.19 mA cm(-2) at 1.23 VRHE with stability, which shows great potential of the use of the Ti-doped SiOx layer with a synergistic effect of decreased charge recombination, the increased number of active sites, and the reduced hole-diffusion pathway from the hematite to the electrolyte. PMID:27358249

  20. Final focus system for high intensity beams

    SciTech Connect

    Henestroza, E.; Bieniosek, F.M.; Eylon, S.; Roy, P.K.; Yu, S.S.


    The NTX experiment at the Heavy Ion Fusion Virtual National Laboratory is exploring the performance of neutralized final focus systems for high perveance heavy ion beams. The NTX final focus system produces a converging beam at the entrance to the neutralized drift section where it focuses to a small spot. The final focus lattice consists of four pulsed quadrupole magnets. The main issues are the control of emittance growth due to high order fields from magnetic multipoles and image fields. We will present experimental results from NTX on beam envelope and phase space distributions, and compare these results with particle simulations using the particle-in-cell code WARP.

  1. Stable Hematite Nanosheet Photoanodes for Enhanced Photoelectrochemical Water Splitting.


    Peerakiatkhajohn, Piangjai; Yun, Jung-Ho; Chen, Hongjun; Lyu, Miaoqiang; Butburee, Teera; Wang, Lianzhou


    A vertically grown hematite nanosheet film modified with Ag nanoparticles (NPs) and Co-Pi cocatalyst exhibits a remarkably high photocurrent density of 4.68 mA cm(-2) at 1.23 V versus RHE. The Ag NPs leads to significantly improved light harvesting and better charge transfer, while the Co-Pi facilitates a highly stable oxygen evolution process. This photoelectrode design provides more efficient photoelectrochemical systems for solar-energy conversion. PMID:27167876

  2. Photoelectrochemical cells including chalcogenophosphate photoelectrodes

    NASA Technical Reports Server (NTRS)

    Reichman, B.; Byvik, C. E. (Inventor)


    Photoelectrochemical cells employing chalcogenophosphate (MPX3) photoelectrodes are described where M is selected from the group of transition metal series of elements beginning with scandium (atomic number 21) through germanium (atomic number 32) yttrium (atomic number 39) through antimony (atomic number 51) and lanthanum (atomic number 57) through polonium (atomic number 84); P is phosphorus; and X is selected from the chalogenide series consisting of sulfur, selenium, and tellurium. These compounds have bandgaps in the desirable range from 2.0 eV to 2.2 eV for the photoelectrolysis of water and are stable when used as photoelectrodes for the same.

  3. Optimization of the NLC final focus system

    SciTech Connect

    Zimmermann, F.; Helm, R.; Irwin, J.


    An optimization scheme for final focus systems is discussed and applied to the NLC design. The optical functions at the defocusing sextupoles, the sextupole strength, and the length of the system must obey eight conditions that are imposed by the spot size increase due to higher-order aberrations, the effects of synchrotron radiation in the bending magnets, power supply ripple, magnet vibration tolerances, and the estimated orbit stability at the sextupoles. These eight conditions determine the minimum optimum length of the system. The NLC final focus design was shortened to this optimum.

  4. Comprehensive Child Welfare Information System. Final rule.



    This final rule replaces the Statewide and Tribal Automated Child Welfare Information Systems (S/TACWIS) rule with the Comprehensive Child Welfare Information System (CCWIS) rule. The rule also makes conforming amendments in rules in related requirements. This rule will assist title IV-E agencies in developing information management systems that leverage new innovations and technology in order to better serve children and families. More specifically, this final rule supports the use of cost-effective, innovative technologies to automate the collection of high-quality case management data and to promote its analysis, distribution, and use by workers, supervisors, administrators, researchers, and policy makers. PMID:27295732

  5. Photoelectrochemical molecular comb


    Thundat, Thomas G.; Ferrell, Thomas L.; Brown; Gilbert M.


    A method, system, and apparatus are provided for separating molecules, such as biomolecules. The method, system, and apparatus utilize an electrochemical cell having at least to electrodes, one electrode comprising a photo-sensitive material capable of generating a photopotential. Molecules are moved through an electrolyte medium between the at least two electrodes based upon localized photopotentials.

  6. Photoelectrochemical molecular comb


    Thundat, Thomas G.; Ferrell, Thomas L; Brown, Gilbert M.


    A method, system, and apparatus are provided for separating molecules, such as biomolecules. The method, system, and apparatus utilize an electrochemical cell having at least two electrodes, one electrode comprising a photo-sensitive material capable of generating a photopotential. Molecules are moved through an electrolyte medium between the at least two electrodes based upon localized photopotentials.

  7. Photoelectrochemical cells based on hydrogen-atom abstraction and electron-transfer reactions in solution: systems based on benzophenone, 2-propanol, trialkylamines, and methyl viologen

    SciTech Connect

    Chandrasekaran, K.; Whitten, D.G.


    This paper reports the linking of well-studied solution photoprocesses such as hydrogen-atom abstraction by triplet benzophenone from 2-propanol and electron transfer from triethylamine to triplet benzophenone to proton reduction in aqueous acid via a two-compartment photoelectrochemical cell. In each case the intermediate reduction of N,N'-dimethyl-4,4'-bipyridinium (methyl viologen, MV/sup 2 +/) provides a means for circumventing undesirable radical reactions and generating a stable carrier in high overall efficiency. The net result is reasonably efficient generation of a photocurrent concurrent with the occurrence of an endothermic reaction providing products that can in principle be recycled. An interesting aspect of this work is the finding that the overall efficiency of these cells is enhanced by the photochemical self-sensitization of MV/sup +/ in the presence of 2-propanol or triethylamine and MV/sup 2 +/.

  8. Final Report Computational Analysis of Dynamical Systems

    SciTech Connect

    Guckenheimer, John


    This is the final report for DOE Grant DE-FG02-93ER25164, initiated in 1993. This grant supported research of John Guckenheimer on computational analysis of dynamical systems. During that period, seventeen individuals received PhD degrees under the supervision of Guckenheimer and over fifty publications related to the grant were produced. This document contains copies of these publications.

  9. Photoelectrochemical hydrogen production

    SciTech Connect

    Rocheleau, R.E.; Miller, E.; Misra, A.


    The large-scale production of hydrogen utilizing energy provided by a renewable source to split water is one of the most ambitious long-term goals of the U.S. Department of Energy`s Hydrogen Program. One promising option to meet this goal is direct photoelectrolysis in which light absorbed by semiconductor-based photoelectrodes produces electrical power internally to split water into hydrogen and oxygen. Under this program, direct solar-to-chemical conversion efficiencies as high as 7.8 % have been demonstrated using low-cost, amorphous-silicon-based photoelectrodes. Detailed loss analysis models indicate that solar-to-chemical conversion greater than 10% can be achieved with amorphous-silicon-based structures optimized for hydrogen production. In this report, the authors describe the continuing progress in the development of thin-film catalytic/protective coatings, results of outdoor testing, and efforts to develop high efficiency, stable prototype systems.

  10. Quantitative photoelectrochemical detection of biological affinity reaction: biotin-avidin interaction.


    Dong, Dong; Zheng, Dong; Wang, Fu-Quan; Yang, Xi-Qiang; Wang, Na; Li, Yuan-Guang; Guo, Liang-Hong; Cheng, Jing


    Quantitative detection of a biological affinity reaction, the biotin/avidin recognition, was achieved using our newly developed photoelectrochemical analytical system. The system is based on the operation mechanism of the well-developed dye-sensitized photoelectrochemical solar cells and comprises a ruthenium tris(2,2'-bipyridine) (Ru-bipy) derivative as the photoelectrochemical signal-generating molecule, oxalate as the sacrificial electron donor, and tin oxide nanoparticle as the semiconductor electrode material. To perform the affinity reaction, avidin was immobilized on SnO(2) electrode by passive adsorption. Biotin-linked bovine serum albumin (BSA) was labeled with an NHS-ester derivative of Ru-bipy. After binding of BSA to the surface-immobilized avidin through biotin, photoelectrochemical measurement was carried out in the presence of oxalate. Anodic photocurrent was turned on and off repeatedly by control of incidental light. The action spectrum of the photocurrent resembled the absorption spectrum of Ru-bipy, proving the photocurrent was generated from the metal complex. A linear relationship between photocurrent and BSA concentration was obtained in the range of 1-100 microg/mL. This is the first case of quantitative photoelectrochemical detection of a biological affinity interaction. PMID:14719905

  11. Superlattice photoelectrodes for photoelectrochemical cells


    Nozik, Arthur J.


    A superlattice or multiple-quantum-well semiconductor is used as a photoelectrode in a photoelectrochemical process for converting solar energy into useful fuels or chemicals. The quantum minibands of the superlattice or multiple-quantum-well semiconductor effectively capture hot-charge carriers at or near their discrete quantum energies and deliver them to drive a chemical reaction in an electrolyte. The hot-charge carries can be injected into the electrolyte at or near the various discrete multiple energy levels quantum minibands, or they can be equilibrated among themselves to a hot-carrier pool and then injected into the electrolyte at one average energy that is higher than the lowest quantum band gap in the semiconductor.

  12. Light addressable photoelectrochemical cyanide sensor

    SciTech Connect

    Licht, S.; Myung, N.; Sun, Y.


    A sensor is demonstrated that is capable of spatial discrimination of cyanide with use of only a single stationary sensing element. Different spatial regions of the sensing element are light activated to reveal the solution cyanide concentration only at the point of illumination. In this light addressable photoelectrochemical (LAP) sensor the sensing element consists of an n-CdSe electrode immersed in solution, with the open-circuit potential determined under illumination. In alkaline ferro-ferri-cyanide solution, the open-circuit photopotential is highly responsive to cyanide, with a linear response of (120 mV) log [KCN]. LAP detection with a spatial resolution of {+-}1 mm for cyanide detection is demonstrated. The response is almost linear for 0.001-0.100 m cyanide with a resolution of 5 mV. 38 refs., 7 figs., 1 tab.

  13. Photoelectrochemical detection of metal ions.


    Zhao, Wei-Wei; Xu, Jing-Juan; Chen, Hong-Yuan


    Depending on the situation, metal ions may either play beneficial roles or be harmful to human health and ecosystems. Sensitive and accurate detection of metal ions is thus a critical issue in the field of analytical sciences and great efforts have been devoted to the development of various metal ion sensors. Photoelectrochemical (PEC) detection is an emerging technique for the bio/chemical detection of metal ions, and features a fast response, low cost and high sensitivity. Using representative examples, this review will first introduce the fundamentals and summarize recent progress in the PEC detection of metal ions. In addition, interesting strategies for the design of particular PEC metal ion sensors are discussed. Challenges and opportunities in this field are also presented. PMID:27297834

  14. Photoelectrochemical sensing of 4-chlorophenol based on Au/BiOCl nanocomposites.


    Yan, Pengcheng; Xu, Li; Xia, Jiexiang; Huang, Yan; Qiu, Jingxia; Xu, Qian; Zhang, Qi; Li, Huaming


    The Au/BiOCl composites have been prepared by a facile one-pot ethylene glycol (EG) assisted solvothermal reaction in the presence of ionic liquid 1-hexadecyl-3-methylimidazolium chloride ([C16mim]Cl). During the synthesis procedure, the [C16mim]Cl has been used as Cl source, solvent of this system, and dispersing agent to effectively disperse Au on the surface of BiOCl. The as-prepared samples have been systematically characterized by multiple instruments to investigate the structure, morphology, and photoelectrochemical properties. According to the photoelectrochemical data, the Au/BiOCl composites exhibit better photoelectrochemical performance toward the detection of 4-chlorophenol than that of the pure BiOCl. The photocurrent response of Au/BiOCl modified electrode is high and stable under light irradiation. The proposed Au/BiOCl modified electrode shows a wide linear response ranging from 0.16 to 20mgL(-1) with detection limit of 0.05mgL(-1). It indicates a dramatically promising application of bismuth oxyhalides in photoelectrochemical detection. It will be expected that the present study may be lightly extended to the monitor of other organic pollutants by photoelectrochemical detection of the Au/BiOCl composites. PMID:27260461

  15. DCE Bio Detection System Final Report

    SciTech Connect

    Lind, Michael A.; Batishko, Charles R.; Morgen, Gerald P.; Owsley, Stanley L.; Dunham, Glen C.; Warner, Marvin G.; Willett, Jesse A.


    The DCE (DNA Capture Element) Bio-Detection System (Biohound) was conceived, designed, built and tested by PNNL under a MIPR for the US Air Force under the technical direction of Dr. Johnathan Kiel and his team at Brooks City Base in San Antonio Texas. The project was directed toward building a measurement device to take advantage of a unique aptamer based assay developed by the Air Force for detecting biological agents. The assay uses narrow band quantum dots fluorophores, high efficiency fluorescence quenchers, magnetic micro-beads beads and selected aptamers to perform high specificity, high sensitivity detection of targeted biological materials in minutes. This final report summarizes and documents the final configuration of the system delivered to the Air Force in December 2008

  16. Multiloop Integral System Test (MIST): Final report

    SciTech Connect

    Klingenfus, J.A.; Parece, M.V.


    The multiloop integral system test (MIST) facility is part of a multiphase program started in 1983 to address small-break loss-of- coolant accidents (SBLOCAs) specific to Babcock Wilcox (B W) designed plants. MIST is sponsored by the US Nuclear Regulatory Commission, the B W Owners group, the Electric Power Research Institute, and B W. The unique features of the B W design, specifically the hot leg U-bends and steam generators, prevented the use of existing integral system data or existing integral system facilities to address the thermal-hydraulic SBLOCA questions. MIST and two other supporting facilities were specifically designed and constructed for this program, and an existing facility -- the once-through integral system (OTIS) -- was also used. Data from MIST and the other facilities will be used to benchmark the adequacy of system codes, such a RELAP5/MOD2 and TRAC-PF1, for predicting abnormal plant transients. The MIST program included funding for seven individual RELAP pre- and post-test predictions. The comparisons against data and final conclusions are the subject of this volume of the MIST Final Report. 15 refs., 227 figs., 17 tabs.

  17. MIST (multiloop integral system test) final report

    SciTech Connect

    Klingenfus, J.A.; Parece, M.V. . Engineering and Plant Services Div.)


    The multiloop integral system test (MIST) facility is part of a multiphase program started in 1983 to address small-break loss-of- coolant accidents (SBLOCAs) specific to Babcock Wilcox (B W) designed plants. MIST is sponsored by the US Nuclear Regulatory Commission, the B W Owners Group, the Electric Power Research Institute, and B W. The unique features of the B W design, specifically the hot leg U-bends and steam generators, prevented the use of existing integral system data or existing integral system facilities to address the thermal-hydraulic SBLOCA questions. MIST and two other supporting facilities were specifically designed and constructed for this program, and an existing facility --- the once-through integral system (OTIS) --- was also used. Data from MIST and the other facilities will be used to benchmark the adequacy of system codes, such as RELAP5/MOD2 and TRAC-PF1, for predicting abnormal plant transients. The MIST program included funding for seven individual RELAP pre- and post-test predictions. The comparisons against data and final conclusions are the subject of this volume of the MIST Final Report. 15 refs., 227 figs., 18 tabs.

  18. Multiple junction II-VI compound photoelectrochemical cells

    NASA Astrophysics Data System (ADS)

    Russak, Michael A.


    The application of concepts used in producing tandem solid state photovoltaic devices to photoelectrochemical cells has resulted in improved spectral response and photovoltaic output. As in solid state devices, the key to achieving good photovoltaic performance is optimization of the semiconductor properties in each part of the tandem arrangement. This has been done for the thin film CdS/CdSe/sulfide-polysulfide system with an improvement of over 15 percent in conversion efficiency being obtained. Preliminary results showing significant current enhancement by the addition of a CdSe backwall electrode to the CdTe/selenide-polyselenide system are also reported.

  19. Photosystem I - based biohybrid photoelectrochemical cells.


    Ciesielski, Peter N; Hijazi, Frederick M; Scott, Amanda M; Faulkner, Christopher J; Beard, Lisa; Emmett, Kevin; Rosenthal, Sandra J; Cliffel, David; Kane Jennings, G


    Photosynthesis is the process by which Nature coordinates a tandem of protein complexes of impressive complexity that function to harness staggering amounts of solar energy on a global scale. Advances in biochemistry and nanotechnology have provided tools to isolate and manipulate the individual components of this process, thus opening a door to a new class of highly functional and vastly abundant biological resources. Here we show how one of these components, Photosystem I (PSI), is incorporated into an electrochemical system to yield a stand-alone biohybrid photoelectrochemical cell that converts light energy into electrical energy. The cells make use of a dense multilayer of PSI complexes assembled on the surface of the cathode to produce a photocatalytic effect that generates photocurrent densities of approximately 2 microA/cm(2) at moderate light intensities. We describe the relationship between the current and voltage production of the cells and the photoinduced interactions of PSI complexes with electrochemical mediators, and show that the performance of the present device is limited by diffusional transport of the electrochemical mediators through the electrolyte. These biohybrid devices display remarkable stability, as they remain active in ambient conditions for at least 280 days. Even at bench-scale production, the materials required to fabricate the cells described in this manuscript cost approximately 10 cents per cm(2) of active electrode area. PMID:20064713

  20. Increasing Efficiency in Photoelectrochemical Hydrogen Production

    SciTech Connect

    Warren, S.; Turner, J.


    Photoelectrochemical hydrogen production promises to be a renewable, clean, and efficient way of storing the sun's energy for use in hydrogen-powered fuel cells. We use p-type Ga.51In.49P semiconductor (henceforth as GaInP2) to absorb solar energy and produce a photocurrent. When the semiconductor is immersed in water, the photocurrent can break down water into hydrogen and oxygen. However, before the GaInP2 can produce hydrogen and oxygen, the conduction band and the Fermi level of the semiconductor must overlap the water redox potentials. In an unmodified system, the conduction band and Fermi level of GaInP2 do not overlap the water redox potentials. When light shines on the semiconductor, electrons build up on the surface, shifting the bandedges and Fermi level further away from overlap of the water redox potentials. We report on surface treatments with metallated porphyrins and transition metals that suppress bandedge migration and allow bandedge overlap to occur. Coating ruthenium octaethylporphyrin carbonyl (RuOEP CO) on the GaInP2 surface shifted bandedges in the positive direction by 270 mV on average, allowing the bandedges to frequently overlap the water redox potentials. Coating the GaInP2 surface with RuCl3 catalyzed charge transfer from the semiconductor to the water, lessening bandedge migration under light irradiation. Future work will focus on the long-term surface stability of these new treatments and quantitative applications of porphyrins.

  1. Facilities management system (FMS). Final report

    SciTech Connect


    The remainder of this report provides a detailed, final status of Andersen Consulting`s participation in the FMS systems implementation project and offers suggestions for continued FMS improvements. The report presents the following topics of discussion: (1) Summary and Status of Work (2) Recommendations for Continued Success (3) Contract Deliverables and Client Satisfaction The Summary and Status of Work section presents a detailed, final status of the FMS project at the termination of Andersen`s full-time participation. This section discusses the status of each FMS sub-system and of the Andersen major project deliverables. The Recommendations section offers suggestions for continued FMS success. The topics discussed include recommendations for each of the following areas: (1) End User and Business Operations (2) AISD; Development and Computer Operations (3) Software (4) Technical Platform (5) Control Procedures The Contract Deliverables and Client Satisfaction section discusses feedback received from Johnson Controls management and FMS system users. The report also addresses Andersen`s observations from the feedback.

  2. Facilities management system (FMS). Final report

    SciTech Connect


    This report provides a detailed, final status of Andersen Consulting`s participation in the Facilities Management System (FMS) implementation project under contract with Los Alamos National Laboratory (LANL) and offers suggestions for continued FMS improvements. The report presents the following topics of discussion: (1) summary and status of work (2) recommendations for continued success (3) contract deliverables and client satisfaction. The Summary and Status of Work section presents a detailed, final status of the FMS project at the termination of Andersen`s full-time participation. This section discusses the status of each FMS sub-system and of the Andersen major project deliverables. The Recommendations section offers suggestions for continued FMS success. The topics discussed include recommendations for each of the following areas: (1) End User and Business Operations; (2) AISD; Development and Computer Operations; (3) Software; (4) Technical Platform; and (5) Control Procedures The Contract Deliverables and Client Satisfaction section discusses feedback received from Johnson Controls management and FMS system users. The report also addresses Andersen`s observations from the feedback.

  3. Jade data transcription system final report

    SciTech Connect

    Eaton, R.; Iskra, M.; McLean, J. . Advanced Technology Div.)


    The OWL sensor, which is used in conjunction with the Jade program, generates a tremendous volume of data during normal field operations. Historically, the dissemination of this data to analysts has been slowed by difficulties in transcribing to a widely readable media and format. TRW, under contract from Lawrence Livermore National Laboratory, was tasked by Defense Advanced Research Projects Agency (DARPA) with finding an improved method of transcribing the Jade experimental data. During the period of performance on this contract TRW helped to guide the development and operation of an improved transcription system. This final report summarizes the work performed, and provides a written record of information which may be helpful to future users of the newly developed data transcription system. 4 figs.

  4. Photoelectrochemical scanning droplet cell microscopy for localized photovoltaic investigations on organic semiconductors.


    Gasiorowski, Jacek; Kollender, Jan Philipp; Hingerl, Kurt; Sariciftci, Niyazi Serdar; Mardare, Andrei Ionut; Hassel, Achim Walter


    Photoelectrochemical characterization of the regioregular poly(3-hexylthiophene) (P3HT) was performed using an adapted version of a photoelectrochemical scanning droplet cell microscope (PE-SDCM). The real and imaginary parts of the dielectric function were determined using spectroscopic ellipsometry in order to identify the absorption region of the polymer. Detailed photoelectrochemical experiments were performed for the thin polymer layer contacted with 0.1 M tetrabutylammonium hexafluorophosphate dissolved in propylene carbonate as well as with an electrolyte containing a 5.4 mM ferrocene/ferrocenium redox couple. The effect of the illumination on the P3HT covered WE in contact with both the pure electrolyte and an electrolyte containing a ferrocene/ferrocenium redox couple was studied using dark/illumination sequences. The stability of the photovoltaic effect was characterized using long term current transients. Finally, the photoelectrochemical impedance spectroscopy was applied to determine the electrical properties of the P3HT in the dark and under illumination. PMID:24424428

  5. Final Report - Regulatory Considerations for Adaptive Systems

    NASA Technical Reports Server (NTRS)

    Wilkinson, Chris; Lynch, Jonathan; Bharadwaj, Raj


    This report documents the findings of a preliminary research study into new approaches to the software design assurance of adaptive systems. We suggest a methodology to overcome the software validation and verification difficulties posed by the underlying assumption of non-adaptive software in the requirementsbased- testing verification methods in RTCA/DO-178B and C. An analysis of the relevant RTCA/DO-178B and C objectives is presented showing the reasons for the difficulties that arise in showing satisfaction of the objectives and suggested additional means by which they could be satisfied. We suggest that the software design assurance problem for adaptive systems is principally one of developing correct and complete high level requirements and system level constraints that define the necessary system functional and safety properties to assure the safe use of adaptive systems. We show how analytical techniques such as model based design, mathematical modeling and formal or formal-like methods can be used to both validate the high level functional and safety requirements, establish necessary constraints and provide the verification evidence for the satisfaction of requirements and constraints that supplements conventional testing. Finally the report identifies the follow-on research topics needed to implement this methodology.

  6. Multiloop integral system test (MIST): Final report

    SciTech Connect

    Gloudemans, J.R. . Nuclear Power Div.)


    The Multiloop Integral System Test (MIST) is part of a multiphase program started in 1983 to address small-break loss-of-coolant accidents (SBLOCAs) specific to Babcock and Wilcox designed plants. MIST is sponsored by the US Nuclear Regulatory Commission, the Babcock Wilcox Owners Group, the Electric Power Research Institute, and Babcock and Wilcox. The unique features of the Babcock and Wilcox design, specifically the hot leg U-bends and steam generators, prevented the use of existing integral system data or existing integral facilities to address the thermal-hydraulic SBLOCA questions. MIST was specifically designed and constructed for this program, and an existing facility -- the Once Through Integral System (OTIS) -- was also used. Data from MIST and OTIS are used to benchmark the adequacy of system codes, such as RELAP5 and TRAC, for predicting abnormal plant transients. The MIST program is reported in 11 volumes. Volumes 2 through 8 pertain to groups of Phase 3 tests by type; Volume 9 presents inter-group comparisons; Volume 10 provides comparisons between the RELAP5/MOD2 calculations and MIST observations, and Volume 11 (with addendum) presents the later Phase 4 tests. This is Volume 1 of the MIST final report, a summary of the entire MIST program. Major topics include, Test Advisory Group (TAG) issues, facility scaling and design, test matrix, observations, comparison of RELAP5 calculations to MIST observations, and MIST versus the TAG issues. MIST generated consistent integral-system data covering a wide range of transient interactions. MIST provided insight into integral system behavior and assisted the code effort. The MIST observations addressed each of the TAG issues. 11 refs., 29 figs., 9 tabs.

  7. An ultrasensitive photoelectrochemical nucleic acid biosensor

    PubMed Central

    Gao, Zhiqiang; Tansil, Natalia C.


    A simple and ultrasensitive procedure for non-labeling detection of nucleic acids is described in this study. It is based on the photoelectrochemical detection of target nucleic acids by forming a nucleic acid/photoreporter adduct layer on an ITO electrode. The target nucleic acids were hybridized with immobilized oligonucleotide capture probes on the ITO electrode. A subsequent binding of a photoreporter—a photoactive threading bis-intercalator consisting of two N,N′-bis(3-propyl-imidazole)-1,4,5,8-naphthalene diimides (PIND) linked by a Ru(bpy)22+ (bpy = 2,2′-bipyridine) complex (PIND–Ru–PIND)—allowed for photoelectrochemical detection of the target nucleic acids. The extremely low dissociation rate of the adduct and the highly reversible photoelectrochemical response under visible light illumination (490 nm) make it possible to conduct nucleic acid detection, with a sensitivity enhancement of four orders of magnitude over voltammetry. These results demonstrate for the first time the potential of photoelectrochemical biosensors for PCR-free ultrasensitive detection of nucleic acids. PMID:16061935

  8. Apollony photonic sponge based photoelectrochemical solar cells.


    Ramiro-Manzano, Fernando; Atienzar, Pedro; Rodriguez, Isabelle; Meseguer, Francisco; Garcia, Hermenegildo; Corma, Avelino


    We have developed a quasi-fractal colloidal crystal to localize efficiently photons in a very broad optical spectral range; it has been applied to prepare dye sensitized photoelectrochemical solar (PES) cells able to harvest very efficiently photons from the ultraviolet (UV) and the visible (VIS) regions of the solar spectrum. PMID:17299626

  9. Multi-Point Combustion System: Final Report

    NASA Technical Reports Server (NTRS)

    Goeke, Jerry; Pack, Spencer; Zink, Gregory; Ryon, Jason


    A low-NOx emission combustor concept has been developed for NASA's Environmentally Responsible Aircraft (ERA) program to meet N+2 emissions goals for a 70,000 lb thrust engine application. These goals include 75 percent reduction of LTO NOx from CAEP6 standards without increasing CO, UHC, or smoke from that of current state of the art. An additional key factor in this work is to improve lean combustion stability over that of previous work performed on similar technology in the early 2000s. The purpose of this paper is to present the final report for the NASA contract. This work included the design, analysis, and test of a multi-point combustion system. All design work was based on the results of Computational Fluid Dynamics modeling with the end results tested on a medium pressure combustion rig at the UC and a medium pressure combustion rig at GRC. The theories behind the designs, results of analysis, and experimental test data will be discussed in this report. The combustion system consists of five radially staged rows of injectors, where ten small scale injectors are used in place of a single traditional nozzle. Major accomplishments of the current work include the design of a Multipoint Lean Direct Injection (MLDI) array and associated air blast and pilot fuel injectors, which is expected to meet or exceed the goal of a 75 percent reduction in LTO NOx from CAEP6 standards. This design incorporates a reduced number of injectors over previous multipoint designs, simplified and lightweight components, and a very compact combustor section. Additional outcomes of the program are validation that the design of these combustion systems can be aided by the use of Computational Fluid Dynamics to predict and reduce emissions. Furthermore, the staging of fuel through the individually controlled radially staged injector rows successfully demonstrated improved low power operability as well as improvements in emissions over previous multipoint designs. Additional comparison

  10. Electron transfer kinetics in water-splitting dye-sensitized photoelectrochemical cells

    NASA Astrophysics Data System (ADS)

    Swierk, John R.

    Water-splitting dye-sensitized photoelectrochemical (WS-DSPECs) cells utilize molecular sensitizers absorbed on mesoporous TiO2 electrodes to harvest visible light, inject photoexcited electrons into the conduction band of TiO2, and finally transfer holes across the TiO2 surface to water oxidation catalysts, which in turn oxidize water to give molecular oxygen and four protons. Within the TiO2 layer photoinjected electrons are transported to a transparent conductor back contact and from there to a dark cathode to reduce protons to molecular hydrogen. WS-DSPECs offer several advantages for alternative solar fuels systems: the use of low-cost materials, tunable molecular sensitizers, and relaxed catalytic turnover requirements to name a few. Despite these advantageous features, power conversion efficiencies in WS-DSPECs are generally low. Broadly, this thesis explores the fundamental electron transfer processes that control the efficiency of these cells. Chapter 1 presents a survey of the previous literature and individually considers each component of a WS-DSPEC (water oxidation catalyst, sensitizers, electrode materials, redox mediators, and overall system design). Chapter 2 presents a novel method of preparing a WS-DSPEC that utilizes crystalline IrO2 nanoparticles directly sintered to TiO2 as a water oxidation catalyst and describes a previously unknown electron-scavenging pathway by IrO2. Chapter 3 explores how electron trapping by and proton intercalation into TiO2 controls the photoelectrochemical performance of WS-DSPECs. Chapter 4 characterizes how electron recombination with the oxidized sensitizer and electron scavenging by the IrO 2 catalyst combine to limit the concentration of conduction band electrons and by extension photocurrent in WS-DSPECs. Chapter 5 demonstrates the use of the first totally organic sensitizers for light driven water-splitting and explores how the molecular and electronic structure of a sensitizer affects the electron transfer

  11. Final Origin of the Saturn System

    NASA Astrophysics Data System (ADS)

    Asphaug, Erik; Reufer, A.


    Saturn’s middle-sized moons (MSMs) are of diverse geology and composition, totaling 4.4% of the system mass. The rest is Titan, with more mass per planet than Jupiter’s satellites combined. Jupiter has four large satellites with 99.998% of the system mass, and no MSMs. Models to explain the discrepancy exist (e.g. Canup 2010; Mosqueira et al. 2010; Charnoz et al. 2011) but have important challenges. We introduce a new hypothesis, in which Saturn starts with a comparable family of major satellites (Ogihara and Ida 2012). These satellites underwent a final sequence of mergers, each occurring at a certain distance from Saturn. Hydrocode simulations show that galilean satellite mergers can liberate ice-rich spiral arms, mostly from the outer layers of the smaller of the accreting pair. These arms gravitate into clumps 100-1000 km diameter that resemble Saturn’s MSMs in diverse composition and other major aspects. Accordingly, a sequence of mergers (ultimately forming Titan) could leave behind populations of MSMs at a couple of formative distances, explaining their wide distribution in semimajor axis. However, MSMs on orbits that cross that of the merged body are rapidly accumulated unless scattered by resonant interactions, or circularized by mutual collisions, or both. Scattering is likely for the first mergers that take place in the presence of other resonant major satellites. Lastly, we consider that the remarkable geophysical and dynamical vigor of Titan and the MSMs might be explained if the proposed sequence of mergers happened late, triggered by impulsive giant planet migration (Morbidelli et al. 2009). The dynamical scenario requires detailed study, and we focus on analysis of the binary collisions. By analysis of the hydrocode models, we relate the provenance of the MSMs to their geophysical aspects (Thomas et al. 2010), and consider the geophysical, thermal and dynamical implications of this hypothesis for Titan’s origin.

  12. Visible light to electrical energy conversion using photoelectrochemical cells

    NASA Technical Reports Server (NTRS)

    Wrighton, Mark S. (Inventor); Ellis, Arthur B. (Inventor); Kaiser, Steven W. (Inventor)


    Sustained conversion of low energy visible or near i.r. light (>1.25 eV) to electrical energy has been obtained using wet photoelectrochemical cells where there are no net chemical changes in the system. Stabilization of n-type semi-conductor anodes of CdS, CdSe, CdTe, GaP, GaAs and InP to photoanodic dissolution is achieved by employing selected alkaline solutions of Na.sub.2 S, Na.sub.2 S/S, Na.sub.2 Se, Na.sub.2 Se/Se, Na.sub.2 Te and Na.sub.2 Te/Te as the electrolyte. The oxidation of (poly) sulfide, (poly)selenide or (poly)telluride species occurs at the irradiated anode, and reduction of polysulfide, polyselenide or polytelluride species occurs at the dark Pt cathode of the photoelectrochemical cell. Optical to electrical energy conversion efficiencies approaching 15% at selected frequencies have been observed in some cells. The wavelength for the onset of photocurrent corresponds to the band gap of the particular anode material used in the cell.

  13. LANL environmental restoration site ranking system: System description. Final report

    SciTech Connect

    Merkhofer, L.; Kann, A.; Voth, M.


    The basic structure of the LANL Environmental Restoration (ER) Site Ranking System and its use are described in this document. A related document, Instructions for Generating Inputs for the LANL ER Site Ranking System, contains detailed descriptions of the methods by which necessary inputs for the system will be generated. LANL has long recognized the need to provide a consistent basis for comparing the risks and other adverse consequences associated with the various waste problems at the Lab. The LANL ER Site Ranking System is being developed to help address this need. The specific purpose of the system is to help improve, defend, and explain prioritization decisions at the Potential Release Site (PRS) and Operable Unit (OU) level. The precise relationship of the Site Ranking System to the planning and overall budget processes is yet to be determined, as the system is still evolving. Generally speaking, the Site Ranking System will be used as a decision aid. That is, the system will be used to aid in the planning and budgetary decision-making process. It will never be used alone to make decisions. Like all models, the system can provide only a partial and approximate accounting of the factors important to budget and planning decisions. Decision makers at LANL will have to consider factors outside of the formal system when making final choices. Some of these other factors are regulatory requirements, DOE policy, and public concern. The main value of the site ranking system, therefore, is not the precise numbers it generates, but rather the general insights it provides.

  14. Dye-sensitized PS-b-P2VP-templated nickel oxide films for photoelectrochemical applications

    PubMed Central

    Massin, Julien; Bräutigam, Maximilian; Kaeffer, Nicolas; Queyriaux, Nicolas; Field, Martin J.; Schacher, Felix H.; Popp, Jürgen; Chavarot-Kerlidou, Murielle; Dietzek, Benjamin; Artero, Vincent


    Moving from homogeneous water-splitting photocatalytic systems to photoelectrochemical devices requires the preparation and evaluation of novel p-type transparent conductive photoelectrode substrates. We report here on the sensitization of polystyrene-block-poly-(2-vinylpyridine) (PS-b-P2VP) diblock copolymer-templated NiO films with an organic push–pull dye. The potential of these new templated NiO film preparations for photoelectrochemical applications is compared with NiO material templated by F108 triblock copolymers. We conclude that NiO films are promising materials for the construction of dye-sensitized photocathodes to be inserted into photoelectrochemical (PEC) cells. However, a combined effort at the interface between materials science and molecular chemistry, ideally funded within a Global Artificial Photosynthesis Project, is still needed to improve the overall performance of the photoelectrodes and progress towards economically viable PEC devices. PMID:26052420

  15. Optical signal demultiplexing and conversion in the fullerene-oligothiophene-CdS system

    NASA Astrophysics Data System (ADS)

    Lewandowska, Kornelia; Podborska, Agnieszka; Kwolek, Przemysław; Kim, Tae-Dong; Lee, Kwang-Sup; Szaciłowski, Konrad


    We report the photoelectrochemical photocurrent switching (PEPS) effect in the system based on a C60 derivatives and nanostructured cadmium sulfide. Rapid and efficient photocurrent switching upon changes of the electrode potential was observed. This process relies on the photocurrent generation by semiconducting particles and interfacial electron transfer reactions governed by the redox chemistry of fullerene derivatives (fullerene-oligothiophene dyads) with molecular oxygen as a final electron acceptor. Surprisingly, fullerene derivatives without thiophene moieties were much less efficient as CdS modifiers. These peculiar photoelectrochemical properties were applied for construction of an optoelectronic logic device.

  16. Soil classifications systems review. Final report

    SciTech Connect


    Systems used to classify soils are discussed and compared. Major types of classification systems that are reviewed include natural systems, technical systems, the FAO/UNESCO world soil map, soil survey map units, and numerical taxonomy. Natural Classification systems discussed in detail are the United States system, Soil Taxonomy, and the Russian and Canadian systems. Included in the section on technical classification systems are reviews on the AASHO and Unified (ASTM) classification systems. The review of soil classification systems was conducted to establish improved availability of accurate ground thermal conductivity and other heat transfer related properties information. These data are intended to help in the design of closed-loop ground heat exchange systems.

  17. Photoelectrochemical water splitting: silicon photocathodes for hydrogen evolution

    NASA Astrophysics Data System (ADS)

    Warren, Emily L.; Boettcher, Shannon W.; McKone, James R.; Lewis, Nathan S.


    The development of low cost, scalable, renewable energy technologies is one of today's most pressing scientific challenges. We report on progress towards the development of a photoelectrochemical water-splitting system that will use sunlight and water as the inputs to produce renewable hydrogen with oxygen as a by-product. This system is based on the design principle of incorporating two separate, photosensitive inorganic semiconductor/liquid junctions to collectively generate the 1.7-1.9 V at open circuit needed to support both the oxidation of H2O (or OH-) and the reduction of H+ (or H2O). Si microwire arrays are a promising photocathode material because the high aspect-ratio electrode architecture allows for the use of low cost, earth-abundant materials without sacrificing energy-conversion efficiency, due to the orthogonalization of light absorption and charge-carrier collection. Additionally, the high surfacearea design of the rod-based semiconductor array inherently lowers the flux of charge carriers over the rod array surface relative to the projected geometric surface of the photoelectrode, thus lowering the photocurrent density at the solid/liquid junction and thereby relaxing the demands on the activity (and cost) of any electrocatalysts. Arrays of Si microwires grown using the Vapor Liquid Solid (VLS) mechanism have been shown to have desirable electronic light absorption properties. We have demonstrated that these arrays can be coated with earth-abundant metallic catalysts and used for photoelectrochemical production of hydrogen. This development is a step towards the demonstration of a complete artificial photosynthetic system, composed of only inexpensive, earth-abundant materials, that is simultaneously efficient, durable, and scalable.

  18. Final Paper DAT Cognitive Art Therapy System

    ERIC Educational Resources Information Center

    Jacobson, Eric


    Del Giacco Art Therapy is a cognitive art therapy process that focuses on stimulating the mental sensory systems and working to stabilize the nervous system and create new neural connections in the brain. This system was created by Maureen Del Giacco, Phd. after recovering from her own traumatic brain injury and is based on extensive research of…

  19. Manzanita Hybrid Power system Project Final Report

    SciTech Connect

    Trisha Frank


    The Manzanita Indian Reservation is located in southeastern San Diego County, California. The Tribe has long recognized that the Reservation has an abundant wind resource that could be commercially utilized to its benefit, and in 1995 the Tribe established the Manzanita Renewable Energy Office. Through the U.S. Department of Energy's Tribal Energy Program the Band received funds to install a hybrid renewable power system to provide electricity to one of the tribal community buildings, the Manzanita Activities Center (MAC building). The project began September 30, 1999 and was completed March 31, 2005. The system was designed and the equipment supplied by Northern Power Systems, Inc, an engineering company with expertise in renewable hybrid system design and development. Personnel of the National Renewable Energy Laboratory provided technical assistance in system design, and continued to provide technical assistance in system monitoring. The grid-connected renewable hybrid wind/photovoltaic system provides a demonstration of a solar/wind energy hybrid power-generating project on Manzanita Tribal land. During the system design phase, the National Renewable Energy Lab estimated that the wind turbine is expected to produce 10,000-kilowatt hours per year and the solar array 2,000-kilowatt hours per year. The hybrid system was designed to provide approximately 80 percent of the electricity used annually in the MAC building. The project proposed to demonstrate that this kind of a system design would provide highly reliable renewable power for community uses.

  20. Solar heating system final design package

    NASA Technical Reports Server (NTRS)


    The system is composed of a warm air collector, a logic control unit and a universal switching and transport unit. The collector was originally conceived and designed as an integrated roof/wall system and therefore provides a dual function in the structure. The collector serves both as a solar energy conversion system and as a structural weather resistant skin. The control unit provides totally automatic control over the operation of the system. It receives input data from sensor probes in collectors, storage and living space. The logic was designed so as to make maximum use of solar energy and minimize use of conventional energy. The transport and switching unit is a high-efficiency air-handling system equipped with gear motor valves that respond to outputs from the control system. The fan unit was designed for maximum durability and efficiency in operation, and has permanently lubricated ball bearings and excellent air-handling efficiency.

  1. Flexible manufacturing system (FMS) evaluation. Final report

    SciTech Connect

    Setter, D.L.


    The applicability of the flexible manufacturing system (FMS) concept to automate machining and inspecting a family of stainless steel and aluminum hardware for electrical components has been evaluated. FMS was found to be appropriate and justifiable and a project was initiated to purchase and implement an FMS system. System specifications and procurement methodologies were developed that resulted in a conventional competitive bid procurement A proposal evaluation technique was developed consisting of 40% price, 40% technical compliance, and 20% supplier management capabilities.

  2. Instructional Support Software System. Final Report.

    ERIC Educational Resources Information Center

    McDonnell Douglas Astronautics Co. - East, St. Louis, MO.

    This report describes the development of the Instructional Support System (ISS), a large-scale, computer-based training system that supports both computer-assisted instruction and computer-managed instruction. Written in the Ada programming language, the ISS software package is designed to be machine independent. It is also grouped into functional…

  3. General Training System; GENTRAS. Final Report.

    ERIC Educational Resources Information Center

    International Business Machines Corp., Gaithersburg, MD. Federal Systems Div.

    GENTRAS (General Training System) is a computer-based training model for the Marine Corps which makes use of a systems approach. The model defines the skill levels applicable for career growth and classifies and defines the training needed for this growth. It also provides a training cost subsystem which will provide a more efficient means of…


    ERIC Educational Resources Information Center



  5. Nanostructured hematite for photoelectrochemical water splitting

    NASA Astrophysics Data System (ADS)

    Ling, Yichuan

    Solar water splitting is an environmentally friendly reaction of producing hydrogen gas. Since Honda and Fujishima first demonstrated solar water splitting in 1972 by using semiconductor titanium dioxide (TiO2) as photoanode in a photoelectrochemical (PEC) cell, extensive efforts have been invested into improving the solar-to-hydrogen (STH) conversion efficiency and lower the production cost of photoelectrochemical devices. In the last few years, hematite (alpha-Fe2O3) nanostructures have been extensively studied as photoanodes for PEC water splitting. Although nanostructured hematite can improve its photoelectrochemical water splitting performance to some extent, by increasing active sites for water oxidation and shortening photogenerated hole path length to semiconductor/electrolyte interface, the photoactivity of pristine hematite nanostructures is still limited by a number of factors, such as poor electrical conductivities and slow oxygen evolution reaction kinetics. Previous studies have shown that tin (Sn) as an n-type dopant can substantially enhance the photoactivity of hematite photoanodes by modifying their optical and electrical properties. In this thesis, I will first demonstrate an unintentional Sn-doping method via high temperature annealing of hematite nanowires grown on fluorine-doped tin oxide (FTO) substrate to enhance the donor density. In addition to introducing extrinsic dopants into semiconductors, the carrier densities of hematite can also be enhanced by creating intrinsic defects. Oxygen vacancies function as shallow donors for a number of hematite. In this regard, I have investigated the influence of oxygen content on thermal decomposition of FeOOH to induce oxygen vacancies in hematite. In the end, I have studied low temperature activation of hematite nanostructures.

  6. Proximity sensor system development. CRADA final report

    SciTech Connect

    Haley, D.C.; Pigoski, T.M.


    Lockheed Martin Energy Research Corporation (LMERC) and Merritt Systems, Inc. (MSI) entered into a Cooperative Research and Development Agreement (CRADA) for the development and demonstration of a compact, modular proximity sensing system suitable for application to a wide class of manipulator systems operated in support of environmental restoration and waste management activities. In teleoperated modes, proximity sensing provides the manipulator operator continuous information regarding the proximity of the manipulator to objects in the workspace. In teleoperated and robotic modes, proximity sensing provides added safety through the implementation of active whole arm collision avoidance capabilities. Oak Ridge National Laboratory (ORNL), managed by LMERC for the United States Department of Energy (DOE), has developed an application specific integrated circuit (ASIC) design for the electronics required to support a modular whole arm proximity sensing system based on the use of capacitive sensors developed at Sandia National Laboratories. The use of ASIC technology greatly reduces the size of the electronics required to support the selected sensor types allowing deployment of many small sensor nodes over a large area of the manipulator surface to provide maximum sensor coverage. The ASIC design also provides a communication interface to support sensor commands from and sensor data transmission to a distributed processing system which allows modular implementation and operation of the sensor system. MSI is a commercial small business specializing in proximity sensing systems based upon infrared and acoustic sensors.

  7. Photoelectrochemical cells - Conversion of intense optical energy

    NASA Technical Reports Server (NTRS)

    Wrighton, M. S.; Ellis, A. B.; Kaiser, S. W.


    Conversion of optical energy to chemical energy and/or electrical energy using wet photoelectrochemical cells is described. Emphasis is on (1) the photoelectrolysis of H2O to H2 and O2 using cells having n-type semiconductor photoelectrodes fabricated from TiO2, SnO2, SrTiO3, KTaO3, and KTa(0.77)Nb(0.23)O3, and (2) the conversion of light to electrical energy using CdSe- and CdS-based cells with polysulfide electrolytes.

  8. Self bleaching photoelectrochemical-electrochromic device


    Bechinger, Clemens S.; Gregg, Brian A.


    A photoelectrochemical-electrochromic device comprising a first transparent electrode and a second transparent electrode in parallel, spaced relation to each other. The first transparent electrode is electrically connected to the second transparent electrode. An electrochromic material is applied to the first transparent electrode and a nanoporous semiconductor film having a dye adsorbed therein is applied to the second transparent electrode. An electrolyte layer contacts the electrochromic material and the nanoporous semiconductor film. The electrolyte layer has a redox couple whereby upon application of light, the nanoporous semiconductor layer dye absorbs the light and the redox couple oxidizes producing an electric field across the device modulating the effective light transmittance through the device.

  9. Water-storage-tube systems. Final report

    SciTech Connect

    Hemker, P.


    Passive solar collection/storage/distribution systems were surveyed, designed, fabricated, and mechanically and thermally tested. The types studied were clear and opaque fiberglass tubes, metal tubes with plastic liners, and thermosyphoning tubes. (MHR)

  10. Analysis of Hybrid Hydrogen Systems: Final Report

    SciTech Connect

    Dean, J.; Braun, R.; Munoz, D.; Penev, M.; Kinchin, C.


    Report on biomass pathways for hydrogen production and how they can be hybridized to support renewable electricity generation. Two hybrid systems were studied in detail for process feasibility and economic performance. The best-performing system was estimated to produce hydrogen at costs ($1.67/kg) within Department of Energy targets ($2.10/kg) for central biomass-derived hydrogen production while also providing value-added energy services to the electric grid.

  11. Semiconductor Nanowires for Photoelectrochemical Water Splitting

    NASA Astrophysics Data System (ADS)

    Hwang, Yun Jeong

    Photolysis of water with semiconductor materials has been investigated intensely as a clean and renewable energy resource by storing solar energy in chemical bonds such as hydrogen. One-dimensional (1D) nanostructures such as nanowires can provide several advantages for photoelectrochemical (PEC) water splitting due to their high surface areas and excellent charge transport and collection efficiency. This dissertation discusses various nanowire photoelectrodes for single or dual semiconductor systems, and their linked PEC cells for self-driven water splitting. After an introduction of solar water splitting in the first chapter, the second chapter demonstrates water oxidative activities of hydrothermally grown TiO2 nanowire arrays depending on their length and surface properties. The photocurrents with TiO2 nanowire arrays approach saturation due to their poor charge collection efficiency with longer nanowires despite increased photon absorption efficiency. Epitaxial grains of rutile atomic layer deposition (ALD) shell on TiO2 nanowire increase the photocurrent density by 1.5 times due to improved charge collection efficiency especially in the short wavelength region. Chapter three compares the photocurrent density of the planar Si and Si nanowire arrays coated by anatase ALD TiO 2 thin film as a model system of a dual bandgap system. The electroless etched Si nanowire coated by ALD TiO2 (Si EENW/TiO2) shows 2.5 times higher photocurrent density due to lower reflectance and higher surface area. Also, this chapter illustrates that n-Si/n-TiO2 heterojunction is a promising structure for the photoanode application of a dual semiconductor system, since it can enhance the photocurrent density compared to p-Si/n-TiO 2 junction with the assistance of bend banding at the interface. Chapter four demonstrates the charge separation and transport of photogenerated electrons and holes within a single asymmetric Si/TiO2 nanowire. Kelvin probe force microscopy measurements show

  12. Final Report Advanced Quasioptical Launcher System

    SciTech Connect

    Jeffrey Neilson


    This program developed an analytical design tool for designing antenna and mirror systems to convert whispering gallery RF modes to Gaussian or HE11 modes. Whispering gallery modes are generated by gyrotrons used for electron cyclotron heating of fusion plasmas in tokamaks. These modes cannot be easily transmitted and must be converted to free space or waveguide modes compatible with transmission line systems.This program improved the capability of SURF3D/LOT, which was initially developed in a previous SBIR program. This suite of codes revolutionized quasi-optical launcher design, and this code, or equivalent codes, are now used worldwide. This program added functionality to SURF3D/LOT to allow creating of more compact launcher and mirror systems and provide direct coupling to corrugated waveguide within the vacuum envelope of the gyrotron. Analysis was also extended to include full-wave analysis of mirror transmission line systems. The code includes a graphical user interface and is available for advanced design of launcher systems.

  13. National Geoscience Data Repository System. Final report

    SciTech Connect

    Schiffries, C.M.; Milling, M.E.


    The American Geological Institute (AGI) has completed the first phase of a study to assess the feasibility of establishing a National Geoscience Data Repository System to capture and preserve valuable geoscientific data. The study was initiated in response to the fact that billions of dollars worth of domestic geological and geophysical data are in jeopardy of being irrevocably lost or destroyed as a consequence of the ongoing downsizing of the US energy and minerals industry. This report focuses on two major issues. First, it documents the types and quantity of data available for contribution to a National Geoscience Data Repository System. Second, it documents the data needs and priorities of potential users of the system. A National Geoscience Data Repository System would serve as an important and valuable source of information for the entire geoscience community for a variety of applications, including environmental protection, water resource management, global change studies, and basic and applied research. The repository system would also contain critical data that would enable domestic energy and minerals companies to expand their exploration and production programs in the United States for improved recovery of domestic oil, gas, and mineral resources.

  14. Autonomous microexplosives subsurface tracing system final report.

    SciTech Connect

    Engler, Bruce Phillip; Nogan, John; Melof, Brian Matthew; Uhl, James Eugene; Dulleck, George R., Jr.; Ingram, Brian V.; Grubelich, Mark Charles; Rivas, Raul R.; Cooper, Paul W.; Warpinski, Norman Raymond; Kravitz, Stanley H.


    The objective of the autonomous micro-explosive subsurface tracing system is to image the location and geometry of hydraulically induced fractures in subsurface petroleum reservoirs. This system is based on the insertion of a swarm of autonomous micro-explosive packages during the fracturing process, with subsequent triggering of the energetic material to create an array of micro-seismic sources that can be detected and analyzed using existing seismic receiver arrays and analysis software. The project included investigations of energetic mixtures, triggering systems, package size and shape, and seismic output. Given the current absence of any technology capable of such high resolution mapping of subsurface structures, this technology has the potential for major impact on petroleum industry, which spends approximately $1 billion dollar per year on hydraulic fracturing operations in the United States alone.

  15. Spill response system configuration study. Final report

    SciTech Connect

    Desimone, R.V.; Agosta, J.M.


    This report describes the development of a prototype decision support system for oil spill response configuration planning that will help U.S. Coast Guard planners to determine the appropriate response equipment and personnel for major spills. The report discusses the application of advanced artificial intelligence planning techniques, as well as other software tools for spill trajectory modeling, plan evaluation and map display. The implementation of the prototype system is discussed in the context of two specific major spill scenarios in the San Francisco Bay.

  16. The final fate of planetary systems

    NASA Astrophysics Data System (ADS)

    Gaensicke, Boris


    The discovery of the first extra-solar planet around a main-sequence star in 1995 has changed the way we think about the Universe: our solar system is not unique. Twenty years later, we know that planetary systems are ubiquitous, orbit stars spanning a wide range in mass, and form in an astonishing variety of architectures. Yet, one fascinating aspect of planetary systems has received relatively little attention so far: their ultimate fate.Most planet hosts will eventually evolve into white dwarfs, Earth-sized stellar embers, and the outer parts of their planetary systems (in the solar system, Mars and beyond) can survive largely intact for billions of years. While scattered and tidally disrupted planetesimals are directly detected at a small number of white dwarfs in the form infrared excess, the most powerful probe for detecting evolved planetary systems is metal pollution of the otherwise pristine H/He atmospheres.I will present the results of a multi-cycle HST survey that has obtained COS observations of 136 white dwarfs. These ultraviolet spectra are exquisitely sensitive to the presence of metals contaminating the white atmosphere. Our sophisticated model atmosphere analysis demonstrates that at least 27% of all targets are currently accreting planetary debris, and an additional 29% have very likely done so in the past. These numbers suggest that planet formation around A-stars (the dominant progenitors of today's white dwarf population) is similarly efficient as around FGK stars.In addition to post-main sequence planetary system demographics, spectroscopy of the debris-polluted white dwarf atmospheres provides a direct window into the bulk composition of exo-planetesimals, analogous to the way we use of meteorites to determine solar-system abundances. Our ultraviolet spectroscopy is particularly sensitive to the detection of Si, a dominant rock-forming species, and we identify up to ten additional volatile and refractory elements in the most strongly

  17. Manipulation of charge transfer and transport in plasmonic-ferroelectric hybrids for photoelectrochemical applications

    NASA Astrophysics Data System (ADS)

    Wang, Zhijie; Cao, Dawei; Wen, Liaoyong; Xu, Rui; Obergfell, Manuel; Mi, Yan; Zhan, Zhibing; Nasori, Nasori; Demsar, Jure; Lei, Yong


    Utilizing plasmonic nanostructures for efficient and flexible conversion of solar energy into electricity or fuel presents a new paradigm in photovoltaics and photoelectrochemistry research. In a conventional photoelectrochemical cell, consisting of a plasmonic structure in contact with a semiconductor, the type of photoelectrochemical reaction is determined by the band bending at the semiconductor/electrolyte interface. The nature of the reaction is thus hard to tune. Here instead of using a semiconductor, we employed a ferroelectric material, Pb(Zr,Ti)O3 (PZT). By depositing gold nanoparticle arrays and PZT films on ITO substrates, and studying the photocurrent as well as the femtosecond transient absorbance in different configurations, we demonstrate an effective charge transfer between the nanoparticle array and PZT. Most importantly, we show that the photocurrent can be tuned by nearly an order of magnitude when changing the ferroelectric polarization in PZT, demonstrating a versatile and tunable system for energy harvesting.

  18. Photoelectrochemical water splitting enhanced by self-assembled metal nanopillars embedded in an oxide semiconductor photoelectrode.


    Kawasaki, Seiji; Takahashi, Ryota; Yamamoto, Takahisa; Kobayashi, Masaki; Kumigashira, Hiroshi; Yoshinobu, Jun; Komori, Fumio; Kudo, Akihiko; Lippmaa, Mikk


    Production of chemical fuels by direct solar energy conversion in a photoelectrochemical cell is of great practical interest for developing a sustainable energy system. Various nanoscale designs such as nanowires, nanotubes, heterostructures and nanocomposites have been explored to increase the energy conversion efficiency of photoelectrochemical water splitting. Here we demonstrate a self-organized nanocomposite material concept for enhancing the efficiency of photocarrier separation and electrochemical energy conversion. Mechanically robust photoelectrodes are formed by embedding self-assembled metal nanopillars in a semiconductor thin film, forming tubular Schottky junctions around each pillar. The photocarrier transport efficiency is strongly enhanced in the Schottky space charge regions while the pillars provide an efficient charge extraction path. Ir-doped SrTiO3 with embedded iridium metal nanopillars shows good operational stability in a water oxidation reaction and achieves over 80% utilization of photogenerated carriers under visible light in the 400- to 600-nm wavelength range. PMID:27255209

  19. Manipulation of charge transfer and transport in plasmonic-ferroelectric hybrids for photoelectrochemical applications

    PubMed Central

    Wang, Zhijie; Cao, Dawei; Wen, Liaoyong; Xu, Rui; Obergfell, Manuel; Mi, Yan; Zhan, Zhibing; Nasori, Nasori; Demsar, Jure; Lei, Yong


    Utilizing plasmonic nanostructures for efficient and flexible conversion of solar energy into electricity or fuel presents a new paradigm in photovoltaics and photoelectrochemistry research. In a conventional photoelectrochemical cell, consisting of a plasmonic structure in contact with a semiconductor, the type of photoelectrochemical reaction is determined by the band bending at the semiconductor/electrolyte interface. The nature of the reaction is thus hard to tune. Here instead of using a semiconductor, we employed a ferroelectric material, Pb(Zr,Ti)O3 (PZT). By depositing gold nanoparticle arrays and PZT films on ITO substrates, and studying the photocurrent as well as the femtosecond transient absorbance in different configurations, we demonstrate an effective charge transfer between the nanoparticle array and PZT. Most importantly, we show that the photocurrent can be tuned by nearly an order of magnitude when changing the ferroelectric polarization in PZT, demonstrating a versatile and tunable system for energy harvesting. PMID:26753764

  20. Manipulation of charge transfer and transport in plasmonic-ferroelectric hybrids for photoelectrochemical applications.


    Wang, Zhijie; Cao, Dawei; Wen, Liaoyong; Xu, Rui; Obergfell, Manuel; Mi, Yan; Zhan, Zhibing; Nasori, Nasori; Demsar, Jure; Lei, Yong


    Utilizing plasmonic nanostructures for efficient and flexible conversion of solar energy into electricity or fuel presents a new paradigm in photovoltaics and photoelectrochemistry research. In a conventional photoelectrochemical cell, consisting of a plasmonic structure in contact with a semiconductor, the type of photoelectrochemical reaction is determined by the band bending at the semiconductor/electrolyte interface. The nature of the reaction is thus hard to tune. Here instead of using a semiconductor, we employed a ferroelectric material, Pb(Zr,Ti)O3 (PZT). By depositing gold nanoparticle arrays and PZT films on ITO substrates, and studying the photocurrent as well as the femtosecond transient absorbance in different configurations, we demonstrate an effective charge transfer between the nanoparticle array and PZT. Most importantly, we show that the photocurrent can be tuned by nearly an order of magnitude when changing the ferroelectric polarization in PZT, demonstrating a versatile and tunable system for energy harvesting. PMID:26753764

  1. Photoelectrochemical water splitting enhanced by self-assembled metal nanopillars embedded in an oxide semiconductor photoelectrode

    PubMed Central

    Kawasaki, Seiji; Takahashi, Ryota; Yamamoto, Takahisa; Kobayashi, Masaki; Kumigashira, Hiroshi; Yoshinobu, Jun; Komori, Fumio; Kudo, Akihiko; Lippmaa, Mikk


    Production of chemical fuels by direct solar energy conversion in a photoelectrochemical cell is of great practical interest for developing a sustainable energy system. Various nanoscale designs such as nanowires, nanotubes, heterostructures and nanocomposites have been explored to increase the energy conversion efficiency of photoelectrochemical water splitting. Here we demonstrate a self-organized nanocomposite material concept for enhancing the efficiency of photocarrier separation and electrochemical energy conversion. Mechanically robust photoelectrodes are formed by embedding self-assembled metal nanopillars in a semiconductor thin film, forming tubular Schottky junctions around each pillar. The photocarrier transport efficiency is strongly enhanced in the Schottky space charge regions while the pillars provide an efficient charge extraction path. Ir-doped SrTiO3 with embedded iridium metal nanopillars shows good operational stability in a water oxidation reaction and achieves over 80% utilization of photogenerated carriers under visible light in the 400- to 600-nm wavelength range. PMID:27255209

  2. Photoelectrochemical water splitting enhanced by self-assembled metal nanopillars embedded in an oxide semiconductor photoelectrode

    NASA Astrophysics Data System (ADS)

    Kawasaki, Seiji; Takahashi, Ryota; Yamamoto, Takahisa; Kobayashi, Masaki; Kumigashira, Hiroshi; Yoshinobu, Jun; Komori, Fumio; Kudo, Akihiko; Lippmaa, Mikk


    Production of chemical fuels by direct solar energy conversion in a photoelectrochemical cell is of great practical interest for developing a sustainable energy system. Various nanoscale designs such as nanowires, nanotubes, heterostructures and nanocomposites have been explored to increase the energy conversion efficiency of photoelectrochemical water splitting. Here we demonstrate a self-organized nanocomposite material concept for enhancing the efficiency of photocarrier separation and electrochemical energy conversion. Mechanically robust photoelectrodes are formed by embedding self-assembled metal nanopillars in a semiconductor thin film, forming tubular Schottky junctions around each pillar. The photocarrier transport efficiency is strongly enhanced in the Schottky space charge regions while the pillars provide an efficient charge extraction path. Ir-doped SrTiO3 with embedded iridium metal nanopillars shows good operational stability in a water oxidation reaction and achieves over 80% utilization of photogenerated carriers under visible light in the 400- to 600-nm wavelength range.

  3. DISCUS Interactive System Users' Manual. Final Report.

    ERIC Educational Resources Information Center

    Silver, Steven S.; Meredith, Joseph C.

    The results of the second 18 months (December 15, 1968-June 30, 1970) of effort toward developing an Information Processing Laboratory for research and education in library science is reported in six volumes. This volume contains: the basic on-line interchange, DISCUS operations, programming in DISCUS, concise DISCUS specifications, system author…

  4. Hydrogen energy systems studies. Final technical report

    SciTech Connect

    Ogden, J.M.; Kreutz, T.; Kartha, S.; Iwan, L.


    The results of previous studies suggest that the use of hydrogen from natural gas might be an important first step toward a hydrogen economy based on renewables. Because of infrastructure considerations (the difficulty and cost of storing, transmitting and distributing hydrogen), hydrogen produced from natural gas at the end-user`s site could be a key feature in the early development of hydrogen energy systems. In the first chapter of this report, the authors assess the technical and economic prospects for small scale technologies for producing hydrogen from natural gas (steam reformers, autothermal reformers and partial oxidation systems), addressing the following questions: (1) What are the performance, cost and emissions of small scale steam reformer technology now on the market? How does this compare to partial oxidation and autothermal systems? (2) How do the performance and cost of reformer technologies depend on scale? What critical technologies limit cost and performance of small scale hydrogen production systems? What are the prospects for potential cost reductions and performance improvements as these technologies advance? (3) How would reductions in the reformer capital cost impact the delivered cost of hydrogen transportation fuel? In the second chapter of this report the authors estimate the potential demand for hydrogen transportation fuel in Southern California.

  5. Multiloop Integral System Test (MIST): Final report

    SciTech Connect

    Geissler, G.O. . Nuclear Power Div. Babcock and Wilcox Co., Alliance, OH . Research and Development Div.)


    The Multiloop Integral System Test (MIST) is part of a multiphase program started in 1983 to address small-break loss-of-coolant accidents (SBLOCAs) specific to Babcock Wilcox designed plants. MIST is sponsored by the US Nuclear Regulatory Commission, the Babcock Wilcox Owners Group, the Electric Power Research Institute, and Babcock and Wilcox. The unique features of the Babcock Wilcox design, specifically the hot leg U-bends and steam generators, prevented the use of existing integral system data or existing integral facilities to address the thermal-hydraulic SBLOCA questions. MIST and two other supporting facilities were specifically designed and constructed for this program, and an existing facility--the Once-Through Integral System (OTIS)--was also used. Data from MIST and the other facilities will be used to benchmark the adequacy of system codes, such as RELAP5 and TRAC, for predication abnormal plant transients. The MIST Program is reported in 11 volumes. The program is summarized in Volume 1; Volumes 2 through 8 describes groups of tests by test type, Volume 9 presents inter-group comparisons, Volume 10 provides comparisons between the calculations of RELAP5/MOD2 and MIST observations, and Volume 11 presents the later Phase 4 tests. This Volume 11 pertains to MIST Phase IV tests performed to investigate risk dominant transients and non-LOCA events. 12 refs., 229 figs., 36 tabs.

  6. Multiloop Integral System Test (MIST): Final report

    SciTech Connect

    Geissler, G.O.


    The Multiloop Integral System Test (MIST) is part of a multiphase program started in 1983 to address small-break loss-of-coolant accidents (SBLOCAs) specific to Babcock Wilcox designed plants. MIST is sponsored by the US Nuclear Regulatory Commission, the Babcock Wilcox Owners Group, the Electric Power Research Institute, and Babcock Wilcox. The unique features of the Babcock Wilcox design, specifically the hot leg U-bends and steam generators, prevented the use of existing integral system data or existing integral facilities to address the thermal-hydraulic SBLOCA questions. MIST and two supporting facilities were specifically designed and constructed for this program, and an existing facility -- the Once-Through Integral System (OTIS) -- was also used. Data from MIST and the other facilities will be used to benchmark the adequacy of system codes, such as RELAP5 and TRAC, for predicting abnormal plant transients. The MIST Program is reported in 11 volumes. The program is summarized in Volume 1; Volumes 2 through 8 describes groups of tests by test type, Volume 9 presents inter-group comparisons; Volume 10 provides comparisons between the calculations of RELAP5/MOD 2 and MIST observations, and Volume 11 presents the later Phase 4 tests. This Volume 11 addendum pertains to MIST natural circulation tests. 2 refs., 161 figs., 8 tabs.

  7. Photoelectrochemical properties of ITO-coated n-type semiconductor electrodes

    NASA Astrophysics Data System (ADS)

    Kraft, Alexander; Heckner, Karl H.


    Because of their high theoretical conversion efficiencies, narrow band gap semiconductors (e.g. Si, GaAs, InP) are most suitable for photoelectrochemical solar energy conversion. unfortunately, they are destroyed by anodic dissolution (photocorrosion) in aqueous electrolytes parallel to photooxidation of electrolyte components. The coating of the semiconductor by a transparent, conductive film is one possibility for corrosion protection. We investigated the suitability of indium tin oxide (ITO) films deposited by different sputter techniques onto n-silicon and n-gallium arsenide substrates. First, the influence of the preparation conditions and of the post deposition annealing treatment on the photovoltaic properties is discussed. Second, the photoelectrochemical properties of the n- semiconductor/ITO electrodes in different aqueous electrolytes containing different redox systems are investigated. n-Si/ITO samples produced by the reactive magetron sputtering technique show the expected corrosion protection behavior, especially in electrolytes with reversible redox systems (e.g. Fe(CN)63-/4-). ITO films deposited by different sputter techniques (reactive magnetron sputtering, d.c. sputtering in different atmospheres) onto n-GaAs are not suitable for corrosion protection purposes. The low Schottky barrier at the n-GaAs/ITO interface and pinholes in the ITO layer are responsible for this behavior. The differences in photoelectrical and photoelectrochemical behavior and in corrosion stability are discussed.

  8. Photoelectrochemical fabrication of spectroscopic diffraction gratings

    NASA Technical Reports Server (NTRS)

    Rauh, R. David; Carrabba, Michael M.; Nguyen, Nguyet M.


    Photoelectrochemical etching was demonstrated as a means of fabricating a variety of periodic structures in semiconductors. The semiconductor is used as an electrode in an electrochemical cell, and is in contact with a liquid electrolyte. When the crystal is held at a positive voltage and illuminated, etching occurs in only the illuminated regions to a depth proportional to the illumination intensity and exposure time. In Phase 1, it was determined that diffraction gratings could be produced in gallium arsenide crystals by this method, using either a scanned focused laser beam or by uniform illumination of a ruling mask defined in metal or photoresist on the crystal surface. The latter approach was determined to produce V-grooves if the mask is oriented along certain crystallographic directions. These V-grooves were produced with an exceedingly smooth crystal morphology due to the highly controllable nature of the process and the mild electrolytes involved. The results form the basis for photoelectrochemical fabrication of deep, low pitch Eschelle gratings for use in high orders in NASA spectrographic instrumentation such as the Space Telescope Imaging Spectrograph.

  9. FY07 Final Report for Calibration Systems

    SciTech Connect

    Myers, Tanya L.; Broocks, Bryan T.; Cannon, Bret D.; Ho, Nicolas


    Remote infrared (IR) sensing provides a valuable method for detection and identification of materials associated with nuclear proliferation. Current challenges for remote sensors include minimizing the size, mass, and power requirements for cheaper, smaller, and more deployable instruments without affecting the measurement performance. One area that is often overlooked is sensor calibration design that is optimized to minimize the cost, size, weight, and power of the payload. Yet, an on-board calibration system is essential to account for changes in the detector response once the instrument has been removed from the laboratory. The Calibration Systems project at Pacific Northwest National Laboratory (PNNL) is aimed towards developing and demonstrating compact quantum cascade (QC) laser-based calibration systems for infrared sensor systems in order to provide both a spectral and radiometric calibration while minimizing the impact on the instrument payload. In FY05, PNNL demonstrated a multi-level radiance scheme that provides six radiance levels for an enhanced linearity check compared to the currently accepted two-point scheme. PNNL began testing the repeatability of this scheme using a cryogenically cooled, single-mode quantum cascade laser (QCL). A cyclic variation in the power was observed that was attributed to the thermal cycling of the laser's dewar. In FY06, PNNL continued testing this scheme and installed an auxiliary liquid nitrogen reservoir to limit the thermal cycling effects. Although better repeatability was achieved over a longer time period, power fluctuations were still observed due to the thermal cycling. Due to the limitations with the cryogenic system, PNNL began testing Fabry-Perot QCLs that operate continuous-wave (cw) or quasi-cw at room temperature (RT) in FY06. PNNL demonstrated a multi-level scheme that provides five radiance levels in 105 seconds with excellent repeatability. We have continued testing this repeatability in FY07. A burn

  10. Final Report of Strongly Interacting Fermion Systems

    SciTech Connect

    Wilkins, J. W.


    There has been significant progress in three broad areas: (A) Optical properties, (B) Large-scale computations, and (C) Many-body systems. In this summary the emphasis is primarily on those papers that point to the research plans. At the same time, some important analytic work is not neglected, some of it even appearing in the description of large-scale Computations. Indeed one of the aims of such computations is to give new insights which lead to development of models capable of simple analytic or nearly analytic analysis.

  11. FY2008 Calibration Systems Final Report

    SciTech Connect

    Cannon, Bret D.; Myers, Tanya L.; Broocks, Bryan T.


    The Calibrations project has been exploring alternative technologies for calibration of passive sensors in the infrared (IR) spectral region. In particular, we have investigated using quantum cascade lasers (QCLs) because these devices offer several advantages over conventional blackbodies such as reductions in size and weight while providing a spectral source in the IR with high output power. These devices can provide a rapid, multi-level radiance scheme to fit any nonlinear behavior as well as a spectral calibration that includes the fore-optics, which is currently not available for on-board calibration systems.

  12. Geophysical tomography imaging system. Final CRADA report

    SciTech Connect

    Norton, S.J.; Won, I.J.


    The Cooperative Research and Development Agreement (CRADA) between Lockheed Martin Energy Systems, Inc., and Geophex, Ltd., was established to investigate high-resolution, shallow acoustic imaging of the subsurface. The primary objectives of the CRADA were accomplished, including the evaluation of a new tomographic imaging algorithm and the testing and comparison of two different acoustic sources, the hammer/plate source and an electromagnetic vibratory source. The imaging system was composed essentially of a linear array of geophones, a digital seismograph, and imaging software installed on a personal computer. Imaging was most successful using the hammer source, which was found to be less susceptible to ground roll (surface wave) interference. It is conjectured that the vibratory source will perform better for deeper targets for which ground roll is less troublesome. Potential applications of shallow acoustic imaging are numerous, including the detection and characterization of buried solid waste, unexploded ordnance, and clandestine man-made underground structures associated with treaty verification (e.g., tunnels, underground storage facilities, hidden bunkers).

  13. Imaging systems for biomedical applications. Final report

    SciTech Connect

    Radparvar, M.


    Many of the activities of the human body manifest themselves by the presence of a very weak magnetic field outside the body, a field that is so weak that an ultra-sensitive magnetic sensor is needed for specific biomagnetic measurements. Superconducting QUantum Interference Devices (SQUIDs) are extremely sensitive detectors of magnetic flux and have been used extensively to detect the human magnetocardiogram, and magnetoencephalogram. and other biomagnetic signals. In order to utilize a SQUID as a magnetometer, its transfer characteristics should be linearized. This linearization requires extensive peripheral electronics, thus limiting the number of SQUID magnetometer channels in a practical system. The proposed digital SQUID integrates the processing circuitry on the same cryogenic chip as the SQUID magnetometer and eliminates the sophisticated peripheral electronics. Such a system is compact and cost effective, and requires minimal support electronics. Under a DOE-sponsored SBIR program, we designed, simulated, laid out, fabricated, evaluated, and demonstrated a digital SQUID magnetometer. This report summarizes the accomplishments under this program and clearly demonstrates that all of the tasks proposed in the phase II application were successfully completed with confirmed experimental results.

  14. Physics of Correlated Systems, Final Project Report

    SciTech Connect

    Greene, Chris H.


    The funding of this DOE project has enabled the P.I. and his collaborators to tackle a number of problems involving nonperturbatively coupled atomic systems, including their interactions with each other and/or with an external electromagnetic field of the type provided by either a continuous-wave or a femtosecond short-pulse laser. The progress includes a new, deeper understanding of an old and famous theory of autoionization lineshapes, developed initially by Ugo Fano in 1935 and later extended in a highly cited 1961 article; the new result specifically is that in a collaboration with the Heidelberg group we have been able to demonstrate an unexpectedly simple behavior in the time domain that is relevant for modern short-pulse lasers. This study also demonstrates a way to modify and even control the lineshapes of unstable atomic and molecular energy levels.

  15. Mirror confinement systems: Final technical report

    SciTech Connect

    Not Available


    This report contains: (1) A discussion of azimuthal asymmetrics and fluctuations in RFC-XX-M. Both lead to enhanced radial transport in RFC-XX-M, and presumably most other tandem mirror machines as well; A report on four operating modes of RFC-XX-M which were developed and studied as part of the collaboration. These operating modes were the simple tandem mode, the negative (floating) potential mode, the hot electron mode, and the ECH (electron cyclotron heating) mode; A pulsed rf heated discharge cleaning system which was developed for RFC-XX-M. This method of cleaning proved much more effective than normal glow discharge cleaning, and variations of it are currently in use on the GAMMA-10 tandem mirror and the JIPP TII-U tokamak at the Institute for Plasma Physics at Nagoya; Short descriptions of the diagnostics development and improvement done in conjunction with the work on RFC-XX-M; and a compilation of the work performed at the University of Tsukuba on GAMMA-10. Most of the effort on GAMMA-10 involved diagnostics development and improvement. 16 refs., 42 figs., 1 tab.

  16. Routes to Ultrahigh Efficiency Photovoltaic and Photoelectrochemical Devices

    SciTech Connect

    Eisler, Carissa; Lloyd, John; Flowers, Cris; Darbe, Sunita; Warmann, Emily; Verlage, Erik; Fountaine, Kate; Hu, Shu; Lewis, Nathan; Atwater, Harry


    We discuss ‘full spectrum’ photovoltaic modules that leverage low-cost III-V compound semiconductor cells, efficient optics and unconventional fabrication/assembly methods, and discuss advances in photoelectrochemical water-splitting with high efficiency.

  17. CdS/MoS2 heterojunction-based photoelectrochemical DNA biosensor via enhanced chemiluminescence excitation.


    Zang, Yang; Lei, Jianping; Hao, Qing; Ju, Huangxian


    This work developed a CdS/MoS2 heterojunction-based photoelectrochemical biosensor for sensitive detection of DNA under the enhanced chemiluminescence excitation of luminol catalyzed by hemin-DNA complex. The CdS/MoS2 photocathode was prepared by the stepwise assembly of MoS2 and CdS quantum dots (QDs) on indium tin oxide (ITO), and achieved about 280% increasing of photocurrent compared to pure CdS QDs electrode due to the formation of heterostructure. High photoconversion efficiency in the photoelectrochemical system was identified to be the rapid spatial charge separation of electron-hole pairs by the extension of electron transport time and electron lifetime. In the presence of target DNA, the catalytic hairpin assembly was triggered, and simultaneously the dual hemin-labeled DNA probe was introduced to capture DNA/CdS/MoS2 modified ITO electrode. Thus the chemiluminescence emission of luminol was enhanced via hemin-induced mimetic catalysis, leading to the physical light-free photoelectrochemical strategy. Under optimized conditions, the resulting photoelectrode was proportional to the logarithm of target DNA concentration in the range from 1 fM to 100 pM with a detection limit of 0.39 fM. Moreover, the cascade amplification biosensor demonstrated high selectivity, desirable stability and good reproducibility, showing great prospect in molecular diagnosis and bioanalysis. PMID:26476013

  18. Solar heating system installed at Troy, Ohio. Final report

    SciTech Connect


    This document is the Final Report of the Solar Energy System located at Troy-Miami County Public Library, Troy, Ohio. The completed system is composed of tree basic subsystems: the collector system consisting of 3264 square feet of Owens Illinois evacuated glass tube collectors; the storage system which includes a 5000-gallon insulated steel tank; and the distribution and control system which includes piping, pumping and control logic for the efficient and safe operation of the entire system. This solar heating system was installed in an existing facility and is, therefore, a retrofit system. This report includes extracts from the site files, specifications, drawings, installation, operation and maintenance instructions.

  19. Photoelectrochemical synthesis of DNA microarrays

    PubMed Central

    Chow, Brian Y.; Emig, Christopher J.; Jacobson, Joseph M.


    Optical addressing of semiconductor electrodes represents a powerful technology that enables the independent and parallel control of a very large number of electrical phenomena at the solid-electrolyte interface. To date, it has been used in a wide range of applications including electrophoretic manipulation, biomolecule sensing, and stimulating networks of neurons. Here, we have adapted this approach for the parallel addressing of redox reactions, and report the construction of a DNA microarray synthesis platform based on semiconductor photoelectrochemistry (PEC). An amorphous silicon photoconductor is activated by an optical projection system to create virtual electrodes capable of electrochemically generating protons; these PEC-generated protons then cleave the acid-labile dimethoxytrityl protecting groups of DNA phosphoramidite synthesis reagents with the requisite spatial selectivity to generate DNA microarrays. Furthermore, a thin-film porous glass dramatically increases the amount of DNA synthesized per chip by over an order of magnitude versus uncoated glass. This platform demonstrates that PEC can be used toward combinatorial bio-polymer and small molecule synthesis. PMID:19706433

  20. Hierarchically branched Fe2O3@TiO2 nanorod arrays for photoelectrochemical water splitting: facile synthesis and enhanced photoelectrochemical performance.


    Li, Yuangang; Wei, Xiaoliang; Zhu, Bowen; Wang, Hua; Tang, Yuxin; Sum, Tze Chien; Chen, Xiaodong


    Highly photoactive and durable photoanode materials are the key to photoelectrochemical water splitting. In this paper, hierarchically branched Fe2O3@TiO2 nanorod arrays (denoted as Fe2O3@TiO2 BNRs) composed of a long Fe2O3 trunk and numerous short TiO2 nanorod branches were fabricated and used as photoanodes for water splitting. Significant improvement of photoelectrochemical water splitting performance was observed based on Fe2O3@TiO2 BNRs. The photocurrent density of Fe2O3@TiO2 BNRs reaches up to 1.3 mA cm(-2) at 1.23 V versus RHE, which is 10 times higher than that of pristine Fe2O3 nanorod arrays under the same conditions. Furthermore, an obvious cathodic shift in the onset potential of photocurrent was observed in the Fe2O3@TiO2 BNRs. More significantly, the Fe2O3@TiO2 BNRs are quite stable even after 3600 s continuous illumination, and the photocurrent density shows almost no decay. Finally, a tentative mechanism was proposed to explain the superior performance of Fe2O3@TiO2 BNRs for PEC water splitting and discussed in detail on the basis of our experimental results. PMID:27189633

  1. Next-Generation Linear Collider Final Focus System Stability Tolerances

    SciTech Connect

    Roy, G.; Irwin, J.; /SLAC


    The design of final focus systems for the next generation of linear colliders has evolved largely from the experience gained with the design and operation of the Stanford Linear Collider (SLC) and with the design of the Final Focus Test Beam (FFTB). We will compare the tolerances for two typical designs for a next-generation linear collider final focus system. The chromaticity generated by strong focusing systems, like the final quadrupole doublet before the interaction point of a linear collider, can be canceled by the introduction of sextupoles in a dispersive region. These sextupoles must be inserted in pairs separated by a -I transformation (Chromatic Correction Section) in order to cancel the strong geometric aberrations generated by sextupoles. Designs proposed for both the JLC or NLC final focus systems have two separate chromatic correction sections, one for each transverse plane separated by a ''{beta}-exchanger'' to manipulate the {beta}-function between the two CCS. The introduction of sextupoles and bending magnets gives rise to higher order aberrations (long sextupole and chrome-geometries) and radiation induced aberrations (chromaticity unbalance and ''Oide effect'') and one must optimize the lattice accordingly.

  2. Final system instrumentation design package for Decade 80 solar house

    NASA Technical Reports Server (NTRS)


    The final configuration of the Decade 80 solar house to monitor and collect system performance data is presented. A review demonstrated by actual operation that the system and the data acquisition subsystem operated satisfactorily and installation of instrumentation was in accordance with the design. This design package is made up of (1) site and system description, (2) operating and control modes, and (3) instrumentation program (including sensor schematic).

  3. Study of Cd-chalcogenide/ferri-ferrocyanide photoelectrochemical cells: effect of surface morphology and added salt

    SciTech Connect

    Tenne, R.


    The authors carried out an investigation of the Cd-chalcogenide/ferri-ferrocyanide photoelectrochemical cells. In particular, the effect of surface morphology and the effect of added salts upon the characteristics of these cells were investigated. Successive etching with Br/sub 2/ (3%)/methanol, aqua regia, and finally photoetching increases the surface roughness of CdSe (CdS, CdTe) which has a marked effect on the cell characteristics in the ferri-ferrocyanide electrolyte (and polysulfide electrolyte as well). In contrast with polysulfide electrolyte, added salts decrease the output stability of the cell and the onset potential for the photocurrent, which can be explained by the removal of the physiosorbed ferrocyanide ions from the electrode surface by the ions of the salt. On increasing the surface roughness of the electrode, while keeping the salt concentration unchanged, the output stability and the onset potential were increased. A kinetic model is used to explain these phenomena. Thus, added salts can be used to probe the strength of the adsorption of the active electrolyte on the surface of the photoelectrode. Finally, we report on the surface morphology of CdSe and CdTe after irradiation in ferri-ferrocyanide solution and compare our findings to surface morphologies which were observed previously with the help of photoelectrochemical etching (photoetching). It is found that small rectangular crystallites, probably of cadmium ferrocyanide, deposit on the crystal surface during the photocorrosion process in addition to elemental Se(Te).

  4. Aural Study Systems for the Visually Handicapped. Final Report.

    ERIC Educational Resources Information Center

    Nolan, Carson Y.; Morris, June E.

    Presented is the final report on development of an aural study system which involved approximately 1000 visually handicapped elementary, secondary, and college students. Given is background information such as the relative effectiveness of reading and listening during study, and factors that affect listening comprehension such as learner…

  5. Instructional Systems Development Model for Interactive Videodisc. Final Report.

    ERIC Educational Resources Information Center

    Campbell, J. Olin; And Others

    This third and final report on a 3-year project, which developed authoring and production procedures for interactive videodisc based on the Interservice Procedures for Instructional Systems Development (IPISD), reviews the current state of the art, provides an overview of the project, and describes two videodiscs made for the project and the…

  6. Study of a final focus system for high intensity beams

    SciTech Connect

    Henestroza, Enrique; Eylon, Shmuel; Roy, Prabir K.; Yu, Simon S.; Bieniosek, Frank M.; Shuman, Derek B.; Waldron, William L.


    The NTX experiment at the Heavy Ion Fusion Virtual National Laboratory is exploring the performance of neutralized final focus systems for high perveance heavy ion beams. The final focus scenario in an HIF driver consists of several large aperture quadrupole magnets followed by a drift section in which the beam space charge is neutralized by a plasma. This beam is required to hit a millimeter-sized target spot at the end of the drift section. The objective of the NTX experiments and associated theory and simulations is to study the various physical mechanisms that determine the final spot size (radius r{sub s}) at a given distance (f) from the end of the last quadrupole. In a fusion driver, f is the standoff distance required to keep the chamber wall and superconducting magnets properly protected. The NTX final quadrupole focusing system produces a converging beam at the entrance to the neutralized drift section where it focuses to a small spot. The final spot is determined by the conditions of the beam entering the quadrupole section, the beam dynamics in the magnetic lattice, and the plasma neutralization dynamics in the drift section. The main issues are the control of emittance growth due to high order fields from magnetic multipoles and image fields. In this paper, we will describe the theoretical and experimental aspects of the beam dynamics in the quadrupole lattice, and how these physical effects influence the final beam size. In particular, we present theoretical and experimental results on the dependence of final spot size on geometric aberrations and perveance.

  7. The Final Focus Test Beam laser referene system

    SciTech Connect

    Bressler, V.E.; Ruland, R.E.


    The original design for the SLAC linac included an alignment reference system with 270 diffraction gratings situated along the 3000 meter linac. These gratings have provided SLAC with a global reference line repeatable to within 200 micro meters. For the Final Focus Test Beam, this laser system has been extended and 13 new diffraction gratings have been installed. Improvements targets and the availability of new instruments allows us to evaluate the performance of the laser reference system at the 510 micro meter level. An explanation of the system and the results of our evaluation are presented.

  8. Photoelectrochemical characterization of the n-InP/Room temperature molten salt electrolyte interface

    NASA Astrophysics Data System (ADS)

    Thapar, R.; Dubow, J.; Rajeshwar, K.


    A study of the photoelectrochemical aspects of the n-InP/AlCl3-butyl pyridinium chloride (BPC) interface is presented. While the features of this system are in semiquantitative accord with the simple model for semiconductor/electrolyte interfaces of Gerischer (1979) and Frank and Bard (1975), departures from ideal behavior caused by specific interactions of electroactive species with the electrode surface are noted for the case of neat AlCl3-BPC electrolytes. Chloraluminate electrolyte systems are shown to be useful mechanistic probes for checking such anomalies and for determining the efficiency of a given photovoltaic electrode/electrolyte combination.

  9. III-Nitride Blue Laser Diode with Photoelectrochemically Etched Current Aperture

    NASA Astrophysics Data System (ADS)

    Megalini, Ludovico

    Group III-nitride is a remarkable material system to make highly efficient and high-power optoelectronics and electronic devices because of the unique electrical, physical, chemical and structural properties it offers. In particular, InGaN-based blue Laser Diodes (LDs) have been successfully employed in a variety of applications ranging from biomedical and military devices to scientific instrumentation and consumer electronics. Recently their use in highly efficient Solid State Lighting (SSL) has been proposed because of their superior beam quality and higher efficiency at high input power density. Tremendous advances in research of GaN semi-polar and non-polar crystallographic planes have led both LEDs and LDs grown on these non-basal planes to rival with, and with the promise to outperform, their equivalent c-plane counterparts. However, still many issues need to be addressed, both related to material growth and device fabrication, including a lack of conventional wet etching techniques. GaN and its alloys with InN and AlN have proven resistant essentially to all known standard wet etching techniques, and the predominant etching methods rely on chlorine-based dry etching (RIE). These introduce sub-surface damage which can degrade the electrical properties of the epitaxial structure and reduce the reliability and lifetime of the final device. Such reasons and the limited effectiveness of passivation techniques have so far suggested to etch the LD ridges before the active region, although it is well-known that this can badly affect the device performance, especially in narrow stripe width LDs, because the gain guiding obtained in the planar configuration is weak and the low index step and high lateral current leakage result in devices with threshold current density higher than devices whose ridge is etched beyond the active region. Moreover, undercut etching of III-nitride layers has proven even more challenging, with limitations in control of the lateral etch


    SciTech Connect

    Seryi, Andrei


    The design of Final Focus systems for linear colliders is challenging because of the large demagnifications needed to produce nanometer-sized beams at the interaction point. Simple first- and second-order matrix matching have proven insufficient for this task, and minimization of third- and higher-order aberrations is essential. An appropriate strategy is required for the latter to be successful. A recipe for Final Focus design, and a set of computational tools used to implement this approach, are described herein. An example of the use of this procedure is given.

  11. Photoelectrochemical conversion using reaction-centre electrodes

    NASA Astrophysics Data System (ADS)

    Janzen, A. F.; Seibert, M.


    The production of photovoltages and photocurrents by a bacterial photosynthetic reaction center coupled to an SnO2 electrode is reported. Reaction centers isolated from membranes of the purple, nonsulfur photosynthetic bacterium Rhodopseudomonas sphaeroides R-26 were transferred to working electrode surfaces and photoeffects were monitored in the external circuit of a photoelectrochemical cell consisting of the working electrode, a platinized platinum or SnO2 counter electrode and a 0.1 M Na2SO4 and 5 M hydroquinone in water or Tricine buffer electrolyte. Small open-circuit photovoltages and short-circuit photocurrents were observed for platinized platinum electrodes coated with a thin film of reaction centers both before and after autoclaving, indicating that biologically active electron transfer is not involved. Reaction-center electrodes made using SnO2-coated glass were observed to generate photovoltages up to 70 mV and photocurrents of 0.3 microamp/sq cm. In addition, the action spectrum of the photocurrent in the external circuit was found to correspond to the absorbance spectra of reaction-center film and solution. It is concluded that charge separation generated across the reaction-center molecule as a result of the primary photochemistry of photosynthesis can be coupled directly to semiconductor electrodes and used to generate photoeffects in an external circuit.

  12. Semiconducting materials for photoelectrochemical energy conversion

    NASA Astrophysics Data System (ADS)

    Sivula, Kevin; van de Krol, Roel


    To achieve a sustainable society with an energy mix primarily based on solar energy, we need methods of storing energy from sunlight as chemical fuels. Photoelectrochemical (PEC) devices offer the promise of solar fuel production through artificial photosynthesis. Although the idea of a carbon-neutral energy economy powered by such ‘artificial leaves’ is intriguing, viable PEC energy conversion on a global scale requires the development of devices that are highly efficient, stable and simple in design. In this Review, recently developed semiconductor materials for the direct conversion of light into fuels are scrutinized with respect to their atomic constitution, electronic structure and potential for practical performance as photoelectrodes in PEC cells. The processes of light absorption, charge separation and transport, and suitable energetics for energy conversion in PEC devices are emphasized. Both the advantageous and unfavourable aspects of multinary oxides, oxynitrides, chalcogenides, classic semiconductors and carbon-based semiconductors are critically considered on the basis of their experimentally demonstrated performance and predicted properties.

  13. Occupational Training Information System. Final Report Complete with System Documentation.

    ERIC Educational Resources Information Center

    Braden, Paul V.; And Others

    The overall purpose of the Occupational Training Information System (OTIS) is to provide improved data for evaluating recommended changes in Oklahoma's State Plan for Vocational Education. In addition to matching manpower supply and demand to show net demand, the project includes components and cost analysis, a followup, underdeveloped human…

  14. Simulated coal gas MCFC power plant system verification. Final report

    SciTech Connect


    The objective of the main project is to identify the current developmental status of MCFC systems and address those technical issues that need to be resolved to move the technology from its current status to the demonstration stage in the shortest possible time. The specific objectives are separated into five major tasks as follows: Stack research; Power plant development; Test facilities development; Manufacturing facilities development; and Commercialization. This Final Report discusses the M-C power Corporation effort which is part of a general program for the development of commercial MCFC systems. This final report covers the entire subject of the Unocal 250-cell stack. Certain project activities have been funded by organizations other than DOE and are included in this report to provide a comprehensive overview of the work accomplished.

  15. Photoelectrochemical fabrication of spectroscopic diffraction gratings, phase 2

    NASA Technical Reports Server (NTRS)

    Rauh, R. David; Carrabba, Michael M.; Li, Jianguo; Cartland, Robert F.; Hachey, John P.; Mathew, Sam


    This program was directed toward the production of Echelle diffraction gratings by a light-driven, electrochemical etching technique (photoelectrochemical etching). Etching is carried out in single crystal materials, and the differential rate of etching of the different crystallographic planes used to define the groove profiles. Etching of V-groove profiles was first discovered by us during the first phase of this project, which was initially conceived as a general exploration of photoelectrochemical etching techniques for grating fabrication. This highly controllable V-groove etching process was considered to be of high significance for producing low pitch Echelles, and provided the basis for a more extensive Phase 2 investigation.

  16. Joint Technical Architecture for Robotic Systems (JTARS)-Final Report

    NASA Technical Reports Server (NTRS)

    Bradley, Arthur T.; Holloway, Sidney E., III


    This document represents the final report for the Joint Technical Architecture for Robotic Systems (JTARS) project, funded by the Office of Exploration as part of the Intramural Call for Proposals of 2005. The project was prematurely terminated, without review, as part of an agency-wide realignment towards the development of a Crew Exploration Vehicle (CEV) and meeting the near-term goals of lunar exploration.

  17. LCLS XTOD Tunnel Vacuum Transport System (XVTS) Final Design Report

    SciTech Connect

    Shen, S


    The design of the X-Ray Vacuum Transport System (XVTS) for the Linac Coherent Light Source (LCLS) X-ray Transport, Optics and Diagnostics (XTOD) system has been analyzed and configured by the Lawrence Livermore National Laboratory's New Technologies Engineering Division (NTED) as requested by the SLAC/LCLS program. A preliminary design review was held on 11/14/05 [1][2]. This FDR (Final Design Report) presents system configuration, detailed analyses and selection of the mechanical and electrical components for the XTOD tunnel section, as well as the response to all issues raised in the review committee report. Also included are the plans for procurement, mechanical integration, schedule and the cost estimates. It should be noticed that, after the XVTS PDR, LCLS management has decided to lower the number of beamlines from three to one, and shorten the tunnel length from 212 m to 184 m. [3][4] The final design of XVTS system is completed. The major subjects presented in this report are: (1) Design of the complete system. (2) System analysis results. (3) ES&H issues and plan. (4) Project cost estimates and schedule.

  18. The final analysis Little Leo: A system and service overview

    SciTech Connect

    Fatig, M.


    There is an emerging commercial space industry consisting of constellations of low earth orbiting satellites to that will provide global telecommunications services. Within the set of proposed low earth orbiting satellite systems, there exists two distinct classes. One class provides high bandwidth digital voice and data services, and the other provides narrowband store and forward digital data services. The digital data service systems are called Little LEOs or Infosats. These systems will provide a variety of personal, business, environmental, and industrial digital data services on a global scale. Infosat systems provide a niche telecommunications infrastructure that benefit industries and governments of the world whether developing or industrialized; geographically homogeneous or diverse; or low, middle, or high income. The flexible nature of the service allows it to be applied in many ways to meet changing needs. This paper provides an overview of the Final Analysis Infosat system. {copyright} {ital 1997 American Institute of Physics.}

  19. One-pot hydrothermal route to fabricate nitrogen doped graphene/Ag-TiO2: Efficient charge separation, and high-performance "on-off-on" switch system based photoelectrochemical biosensing.


    Jiang, Ding; Du, Xiaojiao; Chen, Danyang; Zhou, Lei; Chen, Wei; Li, Yaqi; Hao, Nan; Qian, Jing; Liu, Qian; Wang, Kun


    Charge separation is crucial for increasing the performances of semiconductor-based materials in many photoactive applications. In this paper, we designed novel nanocomposites consisting of TiO2 nanocrystals, Ag nanoparticles (NPs) and nitrogen doped graphene (NGR) via a facile one-pot hydrothermal route. The as-prepared ternary nanocomposites exhibited enhanced photoelectrochemical (PEC) performances owing to the introduction of Ag NPs and NGR, which increase the excitons' lifetime and improve the charge transfer. In particular, it is shown by means of the transient-state surface photocurrent responses that the photocurrent intensity of the as-fabricated composites exhibited 18.2 times higher than that of pristine TiO2. Based on the robust photocurrent signal, a new kind of "on-off-on" PEC aptasensor was established with the assistance of Pb(2+) aptamer, which integrates the advantages of low background signal and high sensitivity. Under optimal conditions, a wide linear response for Pb(2+) detection was obtained from 1pM to 5nM as well as a detection limit down to 0.3pM. With its simplicity, selectivity, and sensitivity, this proposed strategy shows great promise for Pb(2+) detection in food and environment analysis. PMID:27108257

  20. Final report for TMX-U systems support

    SciTech Connect

    Not Available


    This final report is for the TMX-U RF systems development subcontract with Lawrence Livermore National Laboratory (LLNL). This program was initiated on July 1, 1983 and extended through September 30, 1985. This program was concerned with the development of RF systems to meet the objectives of the TMX-U mirror program at LLNL. To accomplish this the following areas were studied during the course of this contract: (1) Ion Cyclotron Heating, (2) Electron Cyclotron Heating, (3) Drift Pumping, (4) Plasma Modeling, (5) Neutral Beam Heating, and (6) Neutral Gas transport and fueling. The key results of these activities are reported.

  1. ZnO nanoflower-based photoelectrochemical DNAzyme sensor for the detection of Pb2+.


    Zhang, Bintian; Lu, Lili; Hu, Qichang; Huang, Feng; Lin, Zhang


    Lead contamination is now widespread, and exposure to lead may cause adverse effects on human beings. In this study, a photoelectrochemical sensor based on flower-like ZnO nanostructures was developed for Pb(2+) detection, using a Pb(2+)-dependent DNAzyme as the recognition unit and a double-strand DNA intercalator, Ru(bpy)2(dppz)(2+) (bpy=2,2'-bipyridine, dppz=dipyrido[3,2-a:2',3'-c] phenazine) as the photoelectrochemical signal reporter. The ZnO nanoflower was fabricated on an indium tin oxide (ITO) electrode by the convenient hydrothermal decomposition method. The morphology and photoelectrochemical property of the ZnO nanoflowers were characterized by SEM, XRD and photocurrent measurements. DNAzyme-substrate duplex was assembled on an ITO/ZnO electrode through electrostatic adsorption. In the presence of Pb(2+), RNA-cleavage activity of the DNAzyme was activated and its substrate strand was cleaved, resulting in the release of Ru(bpy)2(dppz)(2+) from the DNA film and the concomitant photocurrent decrease. The detection principle was verified by fluorescence measurements. Under the optimized conditions, a linear relationship between photocurrent and Pb(2+) concentration was obtained over the range of 0.5-20 nM, with a detection limit of 0.1 nM. Interference from other common metal ions was found negligible. Applicability of the sensor was demonstrated by analyzing lead level in human serum and Pb(2+) spiked water samples. This facile and economical sensor system showed high sensitivity and selectivity, thus can be potentially applied for on-site monitoring of lead contaminant. PMID:24508815

  2. Performance of the 1994/95 SLC final focus system

    SciTech Connect

    Zimmermann, F.; Barklow, T.; Ecklund, S.


    A major upgrade to the SLC final focus was installed in 1994 to eliminate the dominant third-order aberration of the system, and thereby to reduce the vertical beam size at the IP by a factor of two. At low current, the optimal beam size of about 400 nm is now routinely established, and its sensitivity to orbit variations, to changes of emittance and energy spread, and to other beam parameters has been studied. For intensities above 3 {times} 10{sup 10} particles per bunch, tuning is more difficult due to increased fluctuations of energy, orbit, and emittances. Nonetheless, the expected beam size of about 600 nm has been observed. New procedures and diagnostics allow easier tuning and optimization of the final focus, and also a first measurement of the emittance increase in the arcs.

  3. Photovoltaic stand-alone modular systems. Phase 2. Final Report

    SciTech Connect

    Naff, G.J.; Marshall, N.A.


    The final hardware and system qualification phase of a two part stand-alone photovoltaic (PV) system development is covered. The final design incorporated modular, power blocks capable of expanding incrementally from 320 watts to twenty kilowatts (PK). The basic power unit (PU) was nominally rated 1.28 kWp. The controls units, power collection buses and main lugs, electrical protection subsystems, power switching, and load management circuits are housed in a common control enclosure. Photo-voltaic modules are electrically connected in a horizontal daisy-chain method via Amp Solarlok plugs mating with compatible connectors installed on the back side of each photovoltaic module. A pair of channel rails accommodate the mounting of the modules into a frameless panel support structure. Foundations are of a unique planter (tub-like) configuration to allow for world-wide deployment without restriction as to types of soil. One battery string capable of supplying approximately 240 ampere hours nominal of carryover power is specified for each basic power unit. Load prioritization and shedding circuits are included to protect critical loads and selectively shed and defer lower priority or noncritical power demands. The baseline system, operating at approximately 2 1/2 PUs (3.2 kW pk.) was installed and deployed. Qualification was successfully complete in March 1983. Since that time, the demonstration system has logged approximately 3000 hours of continuous operation under load without major incident.

  4. Variable-Speed Wind System Design : Final Report.

    SciTech Connect

    Lauw, Hinan K.; Weigand, Claus H.; Marckx, Dallas A.; Electronic Power Conditioning, Inc.


    Almost from the onset of the development of wind energy conversion systems (WECS), it was known that variable-speed operation of the turbine would maximize energy capture. This study was commissioned to assess the cost, efficiency gain, reduction of the cost of energy (COE), and other operating implications of converting the existing hardware of a modern fixed-speed wind energy conversion system to variable-speed operation. The purpose of this study was to develop a preliminary design for the hardware required to allow variable-speed operation using a doubly-fed generator with an existing fixed-speed wind turbine design. The turbine selected for this study is the AWT-26 designed and built by Advanced Wind Turbines Inc. of Redmond, Washington. The lowest projected COE using this variable-speed generation system is projected to be $0.0499/kWh, compared to the lowest possible COE with fixed-speed generation which is projected to be $0.0546/kWh. This translates into a 8.6% reduction of the COE using this variable-speed generation option. The preliminary system design has advanced to where the printed circuit boards can be physically laid out based on the schematics and the system software can be written based on the control flow-charts. The core of hardware and software has been proven to be successful in earlier versions of VSG systems. The body of this report presents the results of the VSWG system development. Operation under normal and fault conditions is described in detail, the system performance for variable-speed operation is estimated and compared to the original fixed-speed system performance, and specifications for all system components (generator, power electronic converter, and system controller) are given. Costs for all components are estimated, and incremental system cost is compared to incremental energy production. Finally, operational features of the VSWG which are not available in the existing FSWG system are outlined.

  5. Hierarchically branched Fe2O3@TiO2 nanorod arrays for photoelectrochemical water splitting: facile synthesis and enhanced photoelectrochemical performance

    NASA Astrophysics Data System (ADS)

    Li, Yuangang; Wei, Xiaoliang; Zhu, Bowen; Wang, Hua; Tang, Yuxin; Sum, Tze Chien; Chen, Xiaodong


    Highly photoactive and durable photoanode materials are the key to photoelectrochemical water splitting. In this paper, hierarchically branched Fe2O3@TiO2 nanorod arrays (denoted as Fe2O3@TiO2 BNRs) composed of a long Fe2O3 trunk and numerous short TiO2 nanorod branches were fabricated and used as photoanodes for water splitting. Significant improvement of photoelectrochemical water splitting performance was observed based on Fe2O3@TiO2 BNRs. The photocurrent density of Fe2O3@TiO2 BNRs reaches up to 1.3 mA cm-2 at 1.23 V versus RHE, which is 10 times higher than that of pristine Fe2O3 nanorod arrays under the same conditions. Furthermore, an obvious cathodic shift in the onset potential of photocurrent was observed in the Fe2O3@TiO2 BNRs. More significantly, the Fe2O3@TiO2 BNRs are quite stable even after 3600 s continuous illumination, and the photocurrent density shows almost no decay. Finally, a tentative mechanism was proposed to explain the superior performance of Fe2O3@TiO2 BNRs for PEC water splitting and discussed in detail on the basis of our experimental results.Highly photoactive and durable photoanode materials are the key to photoelectrochemical water splitting. In this paper, hierarchically branched Fe2O3@TiO2 nanorod arrays (denoted as Fe2O3@TiO2 BNRs) composed of a long Fe2O3 trunk and numerous short TiO2 nanorod branches were fabricated and used as photoanodes for water splitting. Significant improvement of photoelectrochemical water splitting performance was observed based on Fe2O3@TiO2 BNRs. The photocurrent density of Fe2O3@TiO2 BNRs reaches up to 1.3 mA cm-2 at 1.23 V versus RHE, which is 10 times higher than that of pristine Fe2O3 nanorod arrays under the same conditions. Furthermore, an obvious cathodic shift in the onset potential of photocurrent was observed in the Fe2O3@TiO2 BNRs. More significantly, the Fe2O3@TiO2 BNRs are quite stable even after 3600 s continuous illumination, and the photocurrent density shows almost no decay. Finally

  6. Advanced power conditioning for maglev systems. Final report

    SciTech Connect

    Nerem, A.; Bowles, E.E.; Chapelle, S.; Callanan, R.J.


    The final report contains parametric scaling data and computer models of power conditioning equipment applicable to the design of an advanced maglev system. The power conditioning topologies were selected based on data from a literature search, on characteristics of present power semiconductor technology devices, and on actual performance characterization of designs using a circuit analysis program. The analyses show that GTOs are the best switches for traction drives, input power conditioning equipment, and the braking chopper. At lower power levels, as required for auxiliary power and superconducting coil power conditioning, the IGBT appeared to be the best switch.

  7. ZnO-Au-SnO2 Z-scheme photoanodes for remarkable photoelectrochemical water splitting.


    Li, Jing-Mei; Cheng, Hao-Yun; Chiu, Yi-Hsuan; Hsu, Yung-Jung


    For the first time a ZnO nanorod-based Z-scheme heterostructure system was proposed and realized for efficient photoelectrochemical water splitting. The samples were prepared by depositing a thin layer of SnO2 on the Au surface of Au particle-decorated ZnO nanorods. For ZnO-Au-SnO2 nanorods, the embedded Au can mediate interfacial charge transfer by promoting electron transfer from the conduction band of SnO2 to the valence band of ZnO. This vectorial charge transfer resulted in the situation that the photoexcited electrons accumulated at ZnO while the photogenerated holes concentrated at SnO2, giving ZnO-Au-SnO2 substantially high redox powers. Time-resolved photoluminescence spectra suggested that the interfacial charge transfer across the ZnO/Au/SnO2 interface was significantly improved as a result of the Z-scheme charge transfer mechanism. With the substantially high redox powers and significantly improved interfacial charge transfer, ZnO-Au-SnO2 nanorods performed much better as a photoanode in photoelectrochemical water splitting than pristine ZnO, plasmonic Au-decorated ZnO and type-II SnO2-coated ZnO nanorods did. The present study has provided a viable approach to exploit Z-scheme photoanodes in the design of efficient artificial photosynthesis systems for solar energy conversion. PMID:27527337

  8. In situ-generated nano-gold plasmon-enhanced photoelectrochemical aptasensing based on carboxylated perylene-functionalized graphene.


    Li, Jing; Tu, Wenwen; Li, Hongbo; Han, Min; Lan, Yaqian; Dai, Zhihui; Bao, Jianchun


    A novel in situ-generated nanogold plasmon-enhanced photoelectrochemical aptasensor for Hg(2+) ions was fabricated using a perylene-3,4,9,10-tetracarboxylic acid/graphene (PTCA-GR) heterojunction. The fabricated photoelectrochemical aptasensor was based on thymine-Hg(2+)-thymine coordination chemistry and the plasmonic near-field absorption enhancement effect of the subsequent specific catalytic formation of nanogold. The energetic electrons from the surface plasmons of the nanogold were injected into the LUMO orbit of the organic PTCA semiconductor and then rapidly transferred to the electrode through GR due to the possible Hg(2+)-DNA molecular wires following irradiation with the visible light (λ > 450 nm) and at a bias voltage of 0.2 V. The fabricated aptasensor was linear in its response to the concentration of Hg(2+) ions in the range of 5-500 pmol L(-1), with a detection limit of 2 pmol L(-1). The presence of up to 200-fold greater concentrations of other common metal ions did not interfere with the detection of Hg(2+) ions in an aqueous system, and the results corresponded well with those obtained by ICP-MS. This novel plasmon-enhanced photoelectrochemical aptasensor exhibited good performance with its high sensitivity, good selectivity, low cost, and portable features. The strategy of the localized surface plasmon resonance through the in situ generation of noble metal nanoparticles paves the way for improvements in PEC aptasensor performance. PMID:24377281

  9. Room temperature molten salt electrolytes for photoelectrochemical applications

    SciTech Connect

    Rajeshwar, K.; DuBow, J.; Singh, P.


    Mixtures of aluminum chloride (AlCl/sub 3/) with triethylammonium chloride 1,6-ethyl lutidinium bromide (EtluBr), tert-butyl pyridinium bromide (BPBr), and dialkyl imidazolium chloride (R/sub 2/ImCl), in certain molar ratios yielded ionic liquids at room temperature which were studied with respect to their applicability as electrolytes in photoelectrochemical (PEC) cells. Background voltammograms were obtained for these electrolytes on carbon and n-GaAs electrodes. The anodic stability limit was found to be enhanced on n-GaAs relative to carbon in all cases. The cathodic decomposition potential of the electrolyte showed a smaller positive shift on n-GaAs with the exception of the 3:1 AlCl/sub 3/ BPBr electrolyte. The difference in electrolyte stability behavior on carbon and n-GaAs is interpreted in terms of carrier density effects. Cyclic voltammograms were compared on carbon in the various electrolytes for a model redox system comprising the ferrocene/ferricenium couple. The separation of the cathodic and anodic waves in all the cases was consistent with a quasi-reversible redox behavior--the most sluggish electron transfer being observed in the case of the 3:1 AlCl/sub 3/-BpBr electrolyte. Capacitance-voltage measurements were made on n-GaAs electrodes in contact with the various electrolytes. Flatband-potentials (V /SUB fb/) were deduced from these data using Mott-Schottky plots. The implications of this result for PEC applications and the role of specific ion adsorption of electrolyte species on the electrostatic aspects of the n-GaAs/molten salt electrolyte-interface are discussed with the aid of energy band diagrams.

  10. Final design and status of the NSLS vacuum system

    SciTech Connect

    Schuchman, J.C.


    We describe the final system, as built, reasons for changes and the general status of the NSLS. The NSLS is a dedicated facility for the purpose of producing synchrotron radiation. It consists of an electron linac-booster injector system, and two storage rings, one for uv research and the other for x-ray research. (Synchrotron radiation is produced by accelerating electrons in the storage rings.) The design current and energies are 1000 ma at 700 MeV for the vuv ring and 500 ma at 2.5 GeV for the x-ray ring. A total of 44 experimental beam ports are available for use. Since each beam port may be divided into two or more experimentall beam lines, it is quite plausible to have upward of 100 simultaneously operating beam lines.

  11. Conversion of sunlight into electrical power and photoassisted electrolysis of water in photoelectrochemical cells

    SciTech Connect

    Heller, A.


    The development of photoelectrochemical solar cells based on semiconductor liquid junctions is discussed. Over the past 6 years, the efficiency of solar energy conversion has increased from < 1% to 12%, and the operational life of these cells has increased from hours to months. Understanding the chemistry of surfaces and grain boundaries has made it possible to manipulate the position of the surface and grain boundary states and thus reduce losses due to electron-hole recombination. Cells exhibiting approx. 12% efficiency of conversion are: (1) chemisorbed Ru/sup 3 +/ ions on n-GaAs photoanodes; (2) diffused Ru/sup 3 +/ and Pb/sup 2 +/ into grain boundaries of polycrystalline n-GaAs films on graphite; (3) p-InP/VCl/sub 3/-VCl/sub 2/-HCl/C cell; and (4) p-InP(Ru)/HCl-KCl/Pt cell. Photoassisted electrolysis of water for conversion of solar energy to hydrogen using the last mentioned photoelectrochemical cell represents the most efficient system for solar energy conversion. 61 references are cited. (BLM)tic stainless steel is required to prevent stress corrosion cracking byd stuffs contamination in the USSR takes place in the framework of variations observed in separate countries of northern hemisphere.

  12. Electrodeposition and Screening of Photoelectrochemical Activity in Conjugated Polymers Using Scanning Electrochemical Cell Microscopy.


    Aaronson, Barak D B; Garoz-Ruiz, Jesus; Byers, Joshua C; Colina, Alvaro; Unwin, Patrick R


    A number of renewable energy systems require an understanding and correlation of material properties and photoelectrochemical activity on the micro to nanoscale. Among these, conducting polymer electrodes continue to be important materials. In this contribution, an ultrasensitive scanning electrochemical cell microscopy (SECCM) platform is used to electrodeposit microscale thin films of poly(3-hexylthiophene) (P3HT) on an optically transparent gold electrode and to correlate the morphology (film thickness and structural order) with photoactivity. The electrochemical growth of P3HT begins with a thin ordered film up to 10 nm thick, after which a second more disordered film is deposited, as revealed by micro-Raman spectroscopy. A decrease in photoactivity for the thicker films, measured in situ immediately following film deposition, is attributed to an increase in bulk film disorder that limits charge transport. Higher resolution ex situ SECCM phototransient measurements, using a smaller diameter probe, show local variations in photoactivity within a given deposit. Even after aging, thinner, more ordered regions within a deposit exhibit sustained enhanced photocurrent densities compared to areas where the film is thicker and more disordered. The platform opens up new possibilities for high-throughput combinatorial correlation studies, by allowing materials fabrication and high spatial resolution probing of processes in photoelectrochemical materials. PMID:26502089

  13. Photoelectrochemical oxidation of ibuprofen via Cu2O-doped TiO2 nanotube arrays.


    Sun, Qiannan; Peng, Yen-Ping; Chen, Hanlin; Chang, Ken-Lin; Qiu, Yang-Neng; Lai, Shiau-Wu


    A p-n junction based Cu2O-doped TiO2 nanotube arrays (Cu2O-TNAs) were synthesized and used as a working anode in a photoelectrochemical (PEC) system. The results revealed that the Cu2O-TNAs were dominated by the anatase phase and responded significantly to visible light. XPS analyses indicated that with an amount of 24.79% Cu doping into the structure, the band gap of Cu2O-TNAs was greatly reduced. SEM images revealed that the supported TiO2 nanotubes had diameters of approximately 80nm and lengths of about 2.63μm. Upon doping with Cu2O, the TiO2 nanotubes maintained their structural integrity, exhibiting no significant morphological change, favoring PEC applications. Under illumination, the photocurrent from Cu2O/TNAs was 2.4 times larger than that from TNAs, implying that doping with Cu2O significantly improved electron mobility by reducing the rate of recombination of electron-hole pairs. The EIS and Bode plot revealed that the estimated electron lifetimes, τel, of TNAs and Cu2O/TNAs were 6.91 and 26.26ms, respectively. The efficiencies of degradation of Ibuprofen by photoelectrochemical, photocatalytic (PC), electrochemical (EC) and photolytic (P) methods were measured. PMID:27021261

  14. Label-free and selective photoelectrochemical detection of chemical DNA methylation damage using DNA repair enzymes.


    Wu, Yiping; Zhang, Bintian; Guo, Liang-Hong


    Exogenous chemicals may produce DNA methylation that is potentially toxic to living systems. Methylated DNA bases are difficult to detect with biosensors because the methyl group is small and chemically inert. In this report, a label-free photoelectrochemical sensor was developed for the selective detection of chemically methylated bases in DNA films. The sensor employed two DNA repair enzymes, human alkyladenine DNA glycosylase and human apurinic/apyrimidinic endonuclease, to convert DNA methylation sites in DNA films on indium tin oxide electrodes into strand breaks. A DNA intercalator, Ru(bpy)2(dppz)(2+) (bpy=2,2'-bipyridine, dppz = dipyrido[3,2-a:2',3'-c]phenazine) was then used as the photoelectrochemical signal indicator to detect the DNA strand breaks. Its photocurrent signal was found to correlate inversely with the amount of 3-methyladenines (metAde) produced with a methylating agent, methylmethane sulfonate (MMS). The sensor detected the methylated bases produced with as low as 1 mM MMS, at which concentration the amount of metAde on the sensor surface was estimated to be 0.5 pg, or 1 metAde in 1.6 × 10(5) normal bases. Other DNA base modification products, such as 5-methylcytosine and DNA adducts with ethyl and styrene groups did not attenuate the photocurrent, demonstrating good selectivity of the sensor. This strategy can be utilized to develop sensors for the detection of other modified DNA bases with specific DNA repair enzymes. PMID:23777269

  15. Size-selected TiO₂ nanocluster catalysts for efficient photoelectrochemical water splitting.


    Srivastava, Saurabh; Thomas, Joseph Palathinkal; Rahman, Md Anisur; Abd-Ellah, Marwa; Mohapatra, Mamata; Pradhan, Debabrata; Heinig, Nina F; Leung, Kam Tong


    Nanoclusters (NCs) are of great interest because they provide the link between the distinct behavior of atoms and nanoparticles and that of bulk materials. Here, we report precisely controlled deposition of size-selected TiO2 NCs produced by gas-phase aggregation in a special magnetron sputtering system. Carefully optimized aggregation length and Ar gas flow are used to control the size distribution, while a quadrupole mass filter provides precise in situ size selection (from 2 to 15 nm). Transmission electron microscopy studies reveal that NCs larger than a critical size (∼8 nm) have a crystalline core with an amorphous shell, while those smaller than the critical size are all amorphous. The TiO2 NCs so produced exhibit remarkable photoelectrochemical water splitting performance in spite of a small amount of material loading. NCs of three different sizes (4, 6, and 8 nm) deposited on H-terminated Si(100) substrates are tested for the photoelectrochemical catalytic performance, and significant enhancement in photocurrent density (0.8 mA/cm(2)) with decreasing NC size is observed with a low saturation voltage of -0.22 V vs Ag/AgCl (0.78 V vs RHE). The enhanced photoconductivity could be attributed to the increase in the specific surface area and increase in the number of active (defect) sites in the amorphous NCs. The unique advantages of the present technique will be further exploited to develop applications based on tunable, size-selected NCs. PMID:25365773

  16. The hazardous waste management system--Environmental Protection Agency. Interim final amendments to interim final and final rules.



    The Resource Conservation and Recovery Act (RCRA) requires that EPA set regulatory standards for all facilities which treat, store, or dispose of hazardous waste. In partial implementation of its requirement, on January 23, 1981, EPA set regulatory standards for incinerators that burn hazardous waste. These regulations were issued as "interim final," which means that, although they were issued in final form, the Agency invited public comment on them with a view to future amendment. Today, EPA is amending, on an interim final basis, certain of its regulations applicable to hazardous waste incineration facilities. Today's amendments include revisions to: the general standards for permitting hazardous waste incinerators (Part 264, Subpart O), published in the Federal Register on January 23, 1981; the interim status standards for hazardous waste incinerators (Part 265, Subpart O), revised on January 23, 1981; and the consolidated permit requirements for incinerators (Part 122), published on May 19, 1980 and January 23, 1981.U PMID:10255871

  17. Load leveling on industrial refrigeration systems. Final report

    SciTech Connect

    Bierenbaum, H.S.; Kraus, A.D.


    This project addressed the problem of developing, validating, and demonstrating an optimized methodology for maximizing the benefits of load levelling, energy conservation through efficiency improvements, and reject heat recovery on large, energy intensive industrial compressor systems. A typical industrial food processing plant, a brewery, with a 2000 horsepower compressor/refrigeration system was used as a model facility and as a site for demonstration and validation of strategies developed. The approach used in this work was to construct a computer model of the facility and its energy systems and validate the model against actual data. The next step was to simulate the various conservation and load management options using the validated model. Finally, the savings available for implementing the most promising options were verified by trials in the brewery. Results showed that an optimized methodology for implementing load leveling and energy conservation consisted of first adjusting (or tuning) refrigeration systems controller variables - gain and reset - to minimize unnecessary compressor starts. Second, the primary refrigeration system operating parameters, compressor suction pressure, and discharge pressure are carefully controlled (modulated) to satisfy product quality constraints (as well as in-process material cooling rates and temperature levels) and simultaneously improve energy efficiency and peak demand. Third, energy cost savings for recovery of heat from the reject side of the refrigeration system are estimated using the newly determined compressor operating conditions as a basis for evaluating the energy cost savings associated with reject heat recovery. Fourth, a decision is made to implement the reject heat recovery system based on a cost/benefits analysis.

  18. Expanded bicycling route system for Denver. Final technical report

    SciTech Connect

    Maltempo, M.M.


    This final report describes the results of a study of the potential energy savings associated with increased utilitarian bicycle transportation in the Denver metropolitan area. The project has included computer modeling of the carrying capacity of the present bicycle route system, future route systems, as well as outreach activities to convey the results to public officials and the general public. A key feature of the project has been a consideration of the benefits associated with an expanded bikeway system which includes ''bike boulevards''. Data from the west coast cities and other sources, have been used to generate quantitative estimates of the benefits associated with a Denver bikeway system which includes bike boulevards. The development of a network of bike boulevards in Denver should result in energy savings of about 20.2 million gallons of gasoline per year, as well as a 3.4% reduction in vehicular carbon monoxide emissions. These benefits are in addition to those accruing from current levels of bicycling.

  19. Practical reliability and uncertainty quantification in complex systems : final report.

    SciTech Connect

    Grace, Matthew D.; Ringland, James T.; Marzouk, Youssef M.; Boggs, Paul T.; Zurn, Rena M.; Diegert, Kathleen V.; Pebay, Philippe Pierre; Red-Horse, John Robert


    The purpose of this project was to investigate the use of Bayesian methods for the estimation of the reliability of complex systems. The goals were to find methods for dealing with continuous data, rather than simple pass/fail data; to avoid assumptions of specific probability distributions, especially Gaussian, or normal, distributions; to compute not only an estimate of the reliability of the system, but also a measure of the confidence in that estimate; to develop procedures to address time-dependent or aging aspects in such systems, and to use these models and results to derive optimal testing strategies. The system is assumed to be a system of systems, i.e., a system with discrete components that are themselves systems. Furthermore, the system is 'engineered' in the sense that each node is designed to do something and that we have a mathematical description of that process. In the time-dependent case, the assumption is that we have a general, nonlinear, time-dependent function describing the process. The major results of the project are described in this report. In summary, we developed a sophisticated mathematical framework based on modern probability theory and Bayesian analysis. This framework encompasses all aspects of epistemic uncertainty and easily incorporates steady-state and time-dependent systems. Based on Markov chain, Monte Carlo methods, we devised a computational strategy for general probability density estimation in the steady-state case. This enabled us to compute a distribution of the reliability from which many questions, including confidence, could be addressed. We then extended this to the time domain and implemented procedures to estimate the reliability over time, including the use of the method to predict the reliability at a future time. Finally, we used certain aspects of Bayesian decision analysis to create a novel method for determining an optimal testing strategy, e.g., we can estimate the 'best' location to take the next test to

  20. Silicon Microwire Arrays for Photoelectrochemical and Photovoltaic Applications

    NASA Astrophysics Data System (ADS)

    Warren, Emily Lowell

    Si microwire (Si MW) arrays grown by the vapor-liquid-solid (VLS) process are promising materials for next-generation solar energy devices. High-aspect-ratio semiconductor structures have attracted recent interest as solar absorber materials because their radial geometry decouples the direction of light absorption and carrier collection, enabling the use of materials with shorter minority-carrier diffusion lengths than would be acceptable in a planar geometry. The VLS growth process is a low-cost deposition technique, which can be used to fabricate flexible, high-performance semiconductor materials. Si MW arrays have been investigated as an inexpensive alternative to wafer-based solar photovoltaics for low- cost electricity generation. Another potential application is to use these vertically oriented wire arrays as photocathodes of a solar fuel conversion devices, where instead of producing electricity, sunlight is used to directly drive a fuel-forming reaction (e.g., splitting water to form O 2 and H2). The high aspect ratio of the Si MW arrays provides a large surface area for the integration of fuel-forming catalysts, allowing for the development of a low-cost, scalable, energy storage technology. This thesis discusses the fabrication and photoelectrochemical characterization of Si MWs grown by the VLS process, focusing on the use of these wire arrays as hydrogen- evolving photocathodes for solar water-splitting. To optimize such a device it is important to balance all of the factors that will affect performance: light absorption, band energetics, attainable open circuit voltage, and catalysis. First, we characterize the electrical performance of the wire arrays using regenerative photoelectrochemistry to understand the material quality and band energetics at the Si/water interface. We demonstrate the fabrication of H2-evolving photocathodes using p-n junction Si MW arrays and earth-abundant Ni-Mo alloy hydrogen evolution catalysts. We then investigate modifying

  1. BUBBLES: an Automated Decision Support System for Final Approach Controllers

    NASA Technical Reports Server (NTRS)

    Chi, Zhizang


    With the assumptions that an explicit schedule exists for landings (and takeoffs) at each runway, that each aircraft has declared an IAS for final approach and will be obligated to fly it as accurately as possible, and that there is a continuous estimate of average windspeed on approach, the objective was to provide automated cues to assist controllers in the spacing of landing aircraft. The cues have two characteristics. First, they are adaptive to estimation errors in position and speed by the radar tracking process and piloting errors in the execution of turns and commanded speed reductions. Second, the cues are responsive to the desires of the human controller. Several diagrams are used to help explain the system.

  2. Health Resources Priority and Allocations System (HRPAS). Interim final rule.



    This interim final rule establishes standards and procedures by which the U.S. Department of Health and Human Services (HHS) may require that certain contracts or orders that promote the national defense be given priority over other contracts or orders. This rule also sets new standards and procedures by which HHS may allocate materials, services, and facilities to promote the national defense. This rule will implement HHS's administration of priorities and allocations actions, and establish the Health Resources Priorities and Allocation System (HRPAS). The HRPAS will cover health resources pursuant to the authority under Section 101(c) of the Defense Production Act as delegated to HHS by Executive Order 13603. Priorities authorities (and other authorities delegated to the Secretary in E.O. 13603, but not covered by this regulation) may be re-delegated by the Secretary. The Secretary retains the authority for allocations. PMID:26189218

  3. Urban Integrated Industrial Cogeneration Systems Analysis. Phase II final report

    SciTech Connect

    Not Available


    Through the Urban Integrated Industrial Cogeneration Systems Analysis (UIICSA), the City of Chicago embarked upon an ambitious effort to identify the measure the overall industrial cogeneration market in the city and to evaluate in detail the most promising market opportunities. This report discusses the background of the work completed during Phase II of the UIICSA and presents the results of economic feasibility studies conducted for three potential cogeneration sites in Chicago. Phase II focused on the feasibility of cogeneration at the three most promising sites: the Stockyards and Calumet industrial areas, and the Ford City commercial/industrial complex. Each feasibility case study considered the energy load requirements of the existing facilities at the site and the potential for attracting and serving new growth in the area. Alternative fuels and technologies, and ownership and financing options were also incorporated into the case studies. Finally, site specific considerations such as development incentives, zoning and building code restrictions and environmental requirements were investigated.

  4. Acoustic Resonance Spectroscopy (ARS) Munition Classification System enhancements. Final report

    SciTech Connect

    Vela, O.A.; Huggard, J.C.


    Acoustic Resonance Spectroscopy (ARS) is a non-destructive evaluation technology developed at the Los Alamos National Laboratory (LANL). This technology has resulted in three generations of instrumentation, funded by the Defense Special Weapons Agency (DSWA), specifically designed for field identification of chemical weapon (CW) munitions. Each generation of ARS instrumentation was developed with a specific user in mind. The ARS1OO was built for use by the U.N. Inspection Teams going into Iraq immediately after the Persian Gulf War. The ARS200 was built for use in the US-Russia Bilateral Chemical Weapons Treaty (the primary users for this system are the US Onsite Inspection Agency (OSIA) and their Russian counterparts). The ARS300 was built with the requirements of the Organization for the Prohibition of Chemical Weapons (OPCW) in mind. Each successive system is an improved version of the previous system based on learning the weaknesses of each and, coincidentally, on the fact that more time was available to do a requirements analysis and the necessary engineering development. The ARS300 is at a level of development that warrants transferring the technology to a commercial vendor. Since LANL will supply the computer software to the selected vendor, it is possible for LANL to continue to improve the decision algorithms, add features where necessary, and adjust the user interface before the final transfer occurs. This paper describes the current system, ARS system enhancements, and software enhancements. Appendices contain the Operations Manual (software Version 3.01), and two earlier reports on enhancements.

  5. Ordered titanium dioxide nanotubular arrays: Synthesis, characterization and photoelectrochemical behavior

    NASA Astrophysics Data System (ADS)

    Mahajan, Vishal Khomdeo

    Generation of hydrogen using solar energy and water in a Photo-electrochemical (PEC) system is the most promising method to acquire alternative and renewable energy. Economic feasibility of PEC system requires the energy conversion efficiency (ECE) of 10%, while ensuring high durability of its components. Therefore, the research in this area is based on (i) utilization of renewable sources such as water and solar energy, (ii) improvement in the properties of photoelectrodes to convert maximum of solar energy into hydrogen (chemical energy), (iii) use of environmentally safe materials in the PEC system, (iv) scalability of the process, and (v) durability of the materials used for designing the PEC systems. In present investigation, PEC hydrogen generation was explored by using nanotubular TiO2 photoanodes. One dimensional ordered TiO 2 nanotubes were synthesized by two different techniques. In the first technique, nanotubular TiO2 was prepared in the acidic electrolyte in the presence of fluoride ions. The adventitious one dimensional structure of TiO2 was tested for their material properties by using different characterization tools such as SEM, XRD, UV-VIS and XPS. Effect of heat treatment on their properties was evaluated. In the second TiO2 nanotube synthesis method, organic electrolyte was used. Presence of carbon in the TiO2 nanotubes and its effect on the material properties was studied. Photolectrochemical studies of this material showed increase in the PEC hydrogen generation efficiency after incorporation of the carbon. The process scalability was tested by studying the effect of geometrical area of nanotubular TiO2 photoanodes on its PEC performance. A new Pt/TiO2 cathode was also synthesized by using Pt nanoparticles and TiO2 nanotubes. Newly designed cathode gave similar PEC hydrogen generation efficiency when compared with a Pt foil cathode promising the good performance at low cost. Stability of nanotubular TiO2 arrays was tested by carrying out the

  6. FY 93 Thermal Loading Systems Study Final Report

    SciTech Connect

    S.F. Saterlie


    The objective of the Mined Geologic Disposal System (MGDS) Thermal Loading Systems Study being conducted by the is to identify a thermal strategy that will meet the performance requirements for waste isolation and will be safe and licensable. Specifically, both postclosure and preclosure performance standards must be met by the thermal loading strategy ultimately selected. In addition cost and schedule constraints must be considered. The Systems Engineering approach requires structured, detailed analyses that will ultimately provide the technical basis for the development, integration, and evaluation of the overall system, not just a subelement of that system. It is also necessary that the systems study construct options from within the range that are allowed within the current legislative and programmatic framework. For example the total amount of fuel that can legally be emplaced is no more than 70,000 metric tons of uranium (MTU) which is composed of 63,000 MTU spent fuel and 7,000 MTU of defense high level waste. It is the intent of this study to begin the structured development of the basis for a thermal loading decision. However, it is recognized that to be able to make a final decision on thermal loading will require underground data on the effects of heating as well as a suite of ''validated'' models. It will be some time before these data and models are available to the program. Developing a final, thermal loading decision will, therefore, be an iterative process. In the interim, the objective of the thermal loading systems study has been to utilize the information available to assess the impact of thermal loading. Where technical justification exists, recommendations to narrow the range of thermal loading options can be made. Additionally, recommendations as to the type of testing and accuracy of the testing needed to establish the requisite information will be made. A constraint on the ability of the study to select an option stems from the lack of

  7. Quantum-size-controlled photoelectrochemical etching of semiconductor nanostructures


    Fischer, Arthur J.; Tsao, Jeffrey Y.; Wierer, Jr., Jonathan J.; Xiao, Xiaoyin; Wang, George T.


    Quantum-size-controlled photoelectrochemical (QSC-PEC) etching provides a new route to the precision fabrication of epitaxial semiconductor nanostructures in the sub-10-nm size regime. For example, quantum dots (QDs) can be QSC-PEC-etched from epitaxial InGaN thin films using narrowband laser photoexcitation, and the QD sizes (and hence bandgaps and photoluminescence wavelengths) are determined by the photoexcitation wavelength.

  8. Commercial thermal distribution systems, Final report for CIEE/CEC

    SciTech Connect

    Xu, Tengfang; Bechu, Olivier; Carrie, Remi; Dickerhoff, Darryl; Fisk, William; Franconi, Ellen; Kristiansen, Oyvind; Levinson, Ronnen; McWilliams, Jennifer; Wang, Duo; Modera, Mark; Webster, Tom; Ring, Erik; Zhang, Qiang; Huizenga, Charlie; Bauman, Fred; Arens, Ed


    According to the California Energy Commission (CEC 1998a), California commercial buildings account for 35% of statewide electricity consumption, and 16% of statewide gas consumption. Space conditioning accounts for roughly 16,000 GWh of electricity and 800 million therms of natural gas annually, and the vast majority of this space conditioning energy passes through thermal distribution systems in these buildings. In addition, 8600 GWh per year is consumed by fans and pumps in commercial buildings, most of which is used to move the thermal energy through these systems. Research work at Lawrence Berkeley National Laboratory (LBNL) has been ongoing over the past five years to investigate the energy efficiency of these thermal distribution systems, and to explore possibilities for improving that energy efficiency. Based upon that work, annual savings estimates of 1 kWh/ft{sup 2} for light commercial buildings, and 1-2 kWh/ft{sup 2} in large commercial buildings have been developed for the particular aspects of thermal distribution system performance being addressed by this project. Those savings estimates, combined with a distribution of the building stock based upon an extensive stock characterization study (Modera et al. 1999a), and technical penetration estimates, translate into statewide saving potentials of 2000 GWh/year and 75 million thermal/year, as well as an electricity peak reduction potential of 0.7 GW. The overall goal of this research program is to provide new technology and application knowledge that will allow the design, construction, and energy services industries to reduce the energy waste associated with thermal distribution systems in California commercial buildings. The specific goals of the LBNL efforts over the past year were: (1) to advance the state of knowledge about system performance and energy losses in commercial-building thermal distribution systems; (2) to evaluate the potential of reducing thermal losses through duct sealing, duct

  9. Final Technical Report: Hawaii Hydrogen Center for Development and Deployment of Distributed Energy Systems

    SciTech Connect

    Rocheleau, Richard E.


    Hydrogen power park experiments in Hawai‘i produced real-world data on the performance of commercialized electrochemical components and power systems integrating renewable and hydrogen technologies. By analyzing the different losses associated with the various equipment items involved, this work identifies the different improvements necessary to increase the viability of these technologies for commercial deployment. The stand-alone power system installed at Kahua Ranch on the Big Island of Hawaii required the development of the necessary tools to connect, manage and monitor such a system. It also helped the electrolyzer supplier to adapt its unit to the stand-alone power system application. Hydrogen fuel purity assessments conducted at the Hawai‘i Natural Energy Institute (HNEI) fuel cell test facility yielded additional knowledge regarding fuel cell performance degradation due to exposure to several different fuel contaminants. In addition, a novel fitting strategy was developed to permit accurate separation of the degradation of fuel cell performance due to fuel impurities from other losses. A specific standard MEA and a standard flow field were selected for use in future small-scale fuel cell experiments. Renewable hydrogen production research was conducted using photoelectrochemical (PEC) devices, hydrogen production from biomass, and biohydrogen analysis. PEC device activities explored novel configurations of ‘traditional’ photovoltaic materials for application in high-efficiency photoelectrolysis for solar hydrogen production. The model systems investigated involved combinations of copper-indium-gallium-diselenide (CIGS) and hydrogenated amorphous silicon (a-Si:H). A key result of this work was the establishment of a robust “three-stage” fabrication process at HNEI for high-efficiency CIGS thin film solar cells. The other key accomplishment was the development of models, designs and prototypes of novel ‘four-terminal’ devices integrating high

  10. Electron beam final focus system for Thomson scattering at ELBE

    NASA Astrophysics Data System (ADS)

    Krämer, J. M.; Budde, M.; Bødker, F.; Irman, A.; Jochmann, A.; Kristensen, J. P.; Lehnert, U.; Michel, P.; Schramm, U.


    The design of an electron beam final focus system (FFS) aiming for high-flux laser-Thomson backscattering X-ray sources at ELBE is presented. A telescope system consisting of four permanent magnet based quadrupoles was found to have significantly less chromatic aberrations than a quadrupole doublet or triplet as commonly used. Focusing properties like the position of the focal plane and the spot size are retained for electron beam energies between 20 and 30 MeV by adjusting the position of the quadrupoles individually on a motorized stage. The desired ultra-short electron bunches require an increased relative energy spread up to a few percent and, thus, second order chromatic effects must be taken into account. We also present the design and test results of the permanent magnet quadrupoles. Adjustable shunts allow for correction of the field strength and compensation of deviations in the permanent magnet material. For a beam emittance of 13 mm mrad, we predict focal spot sizes of about 40 μm (rms) and divergences of about 10 mrad using the FFS.

  11. Foundations for Improvements to Passive Detection Systems - Final Report

    SciTech Connect

    Labov, S E; Pleasance, L; Sokkappa, P; Craig, W; Chapline, G; Frank, M; Gronberg, J; Jernigan, J G; Johnson, S; Kammeraad, J; Lange, D; Meyer, A; Nelson, K; Pohl, B; Wright, D; Wurtz, R


    This project explores the scientific foundation and approach for improving passive detection systems for plutonium and highly enriched uranium in real applications. Sources of gamma-ray radiation of interest were chosen to represent a range of national security threats, naturally occurring radioactive materials, industrial and medical radiation sources, and natural background radiation. The gamma-ray flux emerging from these sources, which include unclassified criticality experiment configurations as surrogates for nuclear weapons, were modeled in detail. The performance of several types of gamma-ray imaging systems using Compton scattering were modeled and compared. A mechanism was created to model the combine sources and background emissions and have the simulated radiation ''scene'' impinge on a model of a detector. These modeling tools are now being used in various projects to optimize detector performance and model detector sensitivity in complex measuring environments. This study also developed several automated algorithms for isotope identification from gamma-ray spectra and compared these to each other and to algorithms already in use. Verification testing indicates that these alternative isotope identification algorithms produced less false positive and false negative results than the ''GADRAS'' algorithms currently in use. In addition to these algorithms that used binned spectra, a new approach to isotope identification using ''event mode'' analysis was developed. Finally, a technique using muons to detect nuclear material was explored.

  12. Prototype Engineered Barrier System Field Test (PEBSFT); Final report

    SciTech Connect

    Ramirez, A.L.; Buscheck, T.; Carlson, R.; Daily, W.; Lee, K.; Lin, Wunan; Mao, Nai-hsien; Ueng, Tzou-Shin; Wang, H.; Watwood, D.


    This final report represents a summary of data and interpretations obtained from the Prototype Engineered Barrier System Field Test (PEBSFT) performed in G-Tunnel within the Nevada Test Site. The PEBSFT was conducted to evaluate the applicability of measurement techniques, numerical models, and procedures developed for future field tests that will be conducted in the Exploratory Studies Facilities (ESF) at Yucca Mountain. The primary objective of the test was to provide a basis for determining whether tests planned for the ESF have the potential to be successful. Chapter 1 on high frequency electromagnetic tomography discusses the rock mass electromagnetic permittivity and attenuation rate changes that were measured to characterize the water distribution in the near field of a simulated waste container. The data are used to obtain quantitative estimates of how the moisture content in the rock mass changes during heating and to infer properties of the spatial variability of water distribution, leading to conclusions about the role of fractures in the system. Chapter 2 discusses the changes in rock moisture content detected by the neutron logging probe. Chapter 3 permeability tests discusses the characterization of the in-situ permeability of the fractured tuff around the borehole. The air permeability testing apparatus, the testing procedures, and the data analysis are presented. Chapter 4 describes the moisture collection system installed in the heater borehole to trap and measure the moisture volumes. Chapter 5 describes relative humidity measurements made with the thermocouple psychrometer and capacitance sensors. Chapter 6 discusses gas pressure measurements in the G-Tunnel, addressing the calibration and installation of piezoresistive-gaged transducers. Chapter 7 describes the calibration and installation of thermocouples for temperature measurements. Chapter 8 discusses the results of the PEBSFT.

  13. Critical Research for Cost-Effective Photoelectrochemical Production of Hydrogen

    SciTech Connect

    Xu, Liwei; Deng, Xunming; Abken, Anka; Cao, Xinmin; Du, Wenhui; Vijh, Aarohi; Ingler, William; Chen, Changyong; Fan, Qihua; Collins, Robert; Compaan, Alvin; Yan, Yanfa; Giolando, Dean; Turner, John


    The objective of this project is to develop critical technologies required for cost-effective production of hydrogen from sunlight and water using a-Si triple junction solar cell based photo-electrodes. In this project, Midwest Optoelectronics, LLC (MWOE) and its collaborating organizations utilize triple junction a-Si thin film solar cells as the core element to fabricate photoelectrochemical (PEC) cells. Triple junction a-Si/a-SiGe/a-SiGe solar cell is an ideal material for making cost-effective PEC system which uses sun light to split water and generate hydrogen. It has the following key features: 1) It has an open circuit voltage (Voc ) of ~ 2.3V and has an operating voltage around 1.6V. This is ideal for water splitting. There is no need to add a bias voltage or to inter-connect more than one solar cell. 2) It is made by depositing a-Si/a-SiGe/aSi-Ge thin films on a conducting stainless steel substrate which can serve as an electrode. When we immerse the triple junction solar cells in an electrolyte and illuminate it under sunlight, the voltage is large enough to split the water, generating oxygen at the Si solar cell side (for SS/n-i-p/sunlight structure) and hydrogen at the back, which is stainless steel side. There is no need to use a counter electrode or to make any wire connection. 3) It is being produced in large rolls of 3ft wide and up to 5000 ft long stainless steel web in a 25MW roll-to-roll production machine. Therefore it can be produced at a very low cost. After several years of research with many different kinds of material, we have developed promising transparent, conducting and corrosion resistant (TCCR) coating material; we carried out extensive research on oxygen and hydrogen generation catalysts, developed methods to make PEC electrode from production-grade a-Si solar cells; we have designed and tested various PEC module cases and carried out extensive outdoor testing; we were able to obtain a solar to hydrogen conversion efficiency (STH

  14. Quantum-dot-sensitized TiO2 inverse opals for photoelectrochemical hydrogen generation.


    Cheng, Chuanwei; Karuturi, Siva Krishna; Liu, Lijun; Liu, Jinping; Li, Hongxing; Su, Liap Tat; Tok, Alfred Iing Yoong; Fan, Hong Jin


    A new nanoarchitecture photoelectrode design comprising CdS quantum-dot-sensitized, optically and electrically active TiO(2) inverse opals is developed for photoelectrochemical water splitting. The photoelectrochemical performance shows high photocurrent density (4.84 mA cm(-2) at 0 V vs. Ag/AgCl) under simulated solar-light illumination. PMID:22009604

  15. Astronaut Neil A. Armstrong Undergoes Communications Systems Final Check

    NASA Technical Reports Server (NTRS)


    Dunned in his space suit, mission commander Neil A. Armstrong does a final check of his communications system before before the boarding of the Apollo 11 mission. Launched via a Saturn V launch vehicle, the first manned lunar mission launched from the Kennedy Space Center, Florida on July 16, 1969 and safely returned to Earth on July 24, 1969. The Saturn V vehicle was developed by the Marshall Space Flight Center (MSFC) under the direction of Dr. Wernher von Braun. The 3-man crew aboard the flight consisted of astronauts Armstrong; Michael Collins, Command Module (CM) pilot; and Edwin E. Aldrin, Jr., Lunar Module (LM) Pilot. Armstrong was the first human to ever stand on the lunar surface, followed by Edwin (Buzz) Aldrin. Meanwhile, astronaut Collins piloted the CM in a parking orbit around the Moon. During a 2½ hour surface exploration, the crew collected 47 pounds of lunar surface material which was returned to Earth for analysis. With the success of Apollo 11, the national objective to land men on the Moon and return them safely to Earth had been accomplished.

  16. Optical Diagnostic System for Solar Sails: Phase 1 Final Report

    NASA Technical Reports Server (NTRS)

    Pappa, Richard S.; Blandino, Joseph R.; Caldwell, Douglas W.; Carroll, Joseph A.; Jenkins, Christopher H. M.; Pollock, Thomas C.


    NASA's In-Space Propulsion program recently selected AEC-ABLE Engineering and L'Garde, Inc. to develop scale-model solar sail hardware and demonstrate its functionality on the ground. Both are square sail designs with lightweight diagonal booms (<100 g/m) and ultra-thin membranes (<10 g/sq m). To support this technology, the authors are developing an integrated diagnostics instrumentation package for monitoring solar sail structures such as these in a near-term flight experiment. We refer to this activity as the "Optical Diagnostic System (ODS) for Solar Sails" project. The approach uses lightweight optics and photogrammetric techniques to measure solar sail membrane and boom shape and dynamics, thermography to map temperature, and non-optical sensors including MEMS accelerometers and load cells. The diagnostics package must measure key structural characteristics including deployment dynamics, sail support tension, boom and sail deflection, boom and sail natural frequencies, sail temperature, and sail integrity. This report summarizes work in the initial 6-month Phase I period (conceptual design phase) and complements the final presentation given in Huntsville, AL on January 14, 2004.

  17. Expanded studies of linear collider final focus systems at the Final Focus Test Beam

    SciTech Connect

    Tenenbaum, P.G.


    In order to meet their luminosity goals, linear colliders operating in the center-of-mass energy range from 3,50 to 1,500 GeV will need to deliver beams which are as small as a few Manometers tall, with x:y aspect ratios as large as 100. The Final Focus Test Beam (FFTB) is a prototype for the final focus demanded by these colliders: its purpose is to provide demagnification equivalent to those in the future linear collider, which corresponds to a focused spot size in the FFTB of 1.7 microns (horizontal) by 60 manometers (vertical). In order to achieve the desired spot sizes, the FFTB beam optics must be tuned to eliminate aberrations and other errors, and to ensure that the optics conform to the desired final conditions and the measured initial conditions of the beam. Using a combination of incoming-beam diagnostics. beam-based local diagnostics, and global tuning algorithms, the FFTB beam size has been reduced to a stable final size of 1.7 microns by 70 manometers. In addition, the chromatic properties of the FFTB have been studied using two techniques and found to be acceptable. Descriptions of the hardware and techniques used in these studies are presented, along with results and suggestions for future research.

  18. NIF Final Optics System: Frequency Conversion and Beam Conditioning

    SciTech Connect

    Wegner, P; Auerbach, J; Biesiada, T; Dixit, S; Lawson, J; Menapace, J; Parham, T; Swift, D; Whitman, P; Williams, W


    Installation and commissioning of the first of forty-eight Final Optics Assemblies on the National Ignition Facility was completed this past year. This activity culminated in the delivery of first light to a target. The final optics design is described and selected results from first-article commissioning and performance tests are presented.

  19. Plate-Based Fuel Processing System Final Report

    SciTech Connect

    Carlos Faz; Helen Liu; Jacques Nicole; David Yee


    took the initial steam reforming plate-reactor concept and advanced it towards an integrated fuel processing system. A substantial amount of modeling was performed to guide the catalyst development and prototype hardware design and fabrication efforts. The plate-reactor mechanical design was studied in detail to establish design guidelines which would help the plate reactor survive the stresses of repeated thermal cycles (from start-ups and shut-downs). Integrated system performance modeling was performed to predict system efficiencies and determine the parameters with the most significant impact on efficiency. In conjunction with the modeling effort, a significant effort was directed towards catalyst development. CESI developed a highly active, sulfur tolerant, coke resistant, precious metal based reforming catalyst. CESI also developed its own non-precious metal based water-gas shift catalyst and demonstrated the catalysts durability over several thousands of hours of testing. CESI also developed a unique preferential oxidation catalyst capable of reducing 1% CO to < 10 ppm CO over a 35 C operating window through a single pass plate-based reactor. Finally, CESI combined the modeling results and steam reforming catalyst development efforts into prototype hardware. The first generation 3kW(e) prototype was fabricated from existing heat-exchanger plates to expedite the fabrication process. This prototype demonstrated steady state operation ranging from 5 to 100% load conditions. The prototype also demonstrated a 20:1 turndown ratio, 10:1 load transient operation and rapid start-up capability.

  20. Metal-free organic sensitizers for use in water-splitting dye-sensitized photoelectrochemical cells

    PubMed Central

    Swierk, John R.; Méndez-Hernández, Dalvin D.; McCool, Nicholas S.; Liddell, Paul; Terazono, Yuichi; Pahk, Ian; Tomlin, John J.; Oster, Nolan V.; Moore, Thomas A.; Moore, Ana L.; Gust, Devens; Mallouk, Thomas E.


    Solar fuel generation requires the efficient capture and conversion of visible light. In both natural and artificial systems, molecular sensitizers can be tuned to capture, convert, and transfer visible light energy. We demonstrate that a series of metal-free porphyrins can drive photoelectrochemical water splitting under broadband and red light (λ > 590 nm) illumination in a dye-sensitized TiO2 solar cell. We report the synthesis, spectral, and electrochemical properties of the sensitizers. Despite slow recombination of photoinjected electrons with oxidized porphyrins, photocurrents are low because of low injection yields and slow electron self-exchange between oxidized porphyrins. The free-base porphyrins are stable under conditions of water photoelectrolysis and in some cases photovoltages in excess of 1 V are observed. PMID:25583488

  1. Wireless InGaN–Si/Pt device for photo-electrochemical water splitting

    NASA Astrophysics Data System (ADS)

    Sekimoto, Takeyuki; Hashiba, Hiroshi; Shinagawa, Shuichi; Uetake, Yusuke; Deguchi, Masahiro; Yotsuhashi, Satoshi; Ohkawa, Kazuhiro


    We demonstrate a wireless device comprising a gallium nitride (GaN)–silicon-based photo-electrode, and a platinum cathode. Compared with conventional two-electrode photo-electrochemical systems, this wireless monolithic device showed potential for a wider range of applications, and reduced the resistance losses resulting from the wiring and aqueous solution. The efficiency was improved when the electrolyte was changed from KHCO3 to NaOH because water oxidation capability of the surface of the GaN was enhanced. A wider solar spectrum wavelength range was exploited by adopting InGaN as a photo-absorption layer; the improved efficiency for hydrogen generation was 0.90%.

  2. Hydrothermal synthesis of Fe2O3/ZnO heterojunction photoanode for photoelectrochemical water splitting

    NASA Astrophysics Data System (ADS)

    Chen, Chao; Bai, Hongye; da, Zulin; Li, Meng; Yan, Xu; Jiang, Jinhui; Fan, Weiqiang; Shi, Weidong


    We report a photoanode based on Fe2O3/zinc oxide (ZnO) heterojunction synthesized by hydrothermal method for photoelectrochemical (PEC) water splitting. The forming heterojunction is systemically characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The results from the I-V characteristic curve and conversation efficiency of Fe2O3/ZnO heterojunction reveal that the forming heterojunction would be a benefit for electron transferring from conduction band of ZnO to that of Fe2O3. However, the quantity of ZnO film has an effect on the photocurrent density, the suitable of which has shown enhanced PEC performance.

  3. Simultaneous photoelectrochemical and visualized immunoassay of β-human chorionic gonadotrophin.


    Zhang, Nan; Ruan, Yi-Fan; Ma, Zheng-Yuan; Zhao, Wei-Wei; Xu, Jing-Juan; Chen, Hong-Yuan


    Herein, on the basis of the alkaline phosphate (ALP) induced reaction, a simultaneous photoelectrochemical (PEC) and visualized immunoassay has been established for the detection of β-human chorionic gonadotrophin (β-HCG). Specifically, in the proposed system, ALP stimulated the oxidative hydrolyzing transformation of 5-bromo-4-chloro-3-indoyl phosphate (BCIP) to an indigo precipitation, generating an insulating layer that impeded the interfacial mass and electron transfer and thus the photocurrent production. Meanwhile, a visualized detection could be performed according to the change of color intensity. Upon proper experimental conditions, the protocol possessed a detection range of 0.5-1000IU/L with a detection limit of (0.20±0.011)IU/L toward β-HCG. With high sensitivity and specificity, this work presents the first general protocol for simultaneous PEC and visualized detection, which could be easily extended to addressing numerous other targets. PMID:27183279

  4. A final focus system for the Next Linear Collider

    SciTech Connect

    Zimmermann, F.; Brown, K.; Emma, P.; Helm, R.; Irwin, J.; Tenenbaum, P.; Wilson, P.


    The final focus of the Next Linear Collider (NLC) demagnifies electron and positron beams of 250--750 GeV energy down to a transverse size of about 2.5 {times} 350 nm{sup 2} at the interaction point (IP). The basic layout, momentum bandwidth, vibration tolerances, wakefield effects, and the tunability of the proposed final focus design are discussed. Also a perspective is given on the crab cavity and on effects of the solenoid field in the interaction region.

  5. Biomolecule-free, selective detection of o-diphenol and its derivatives with WS2/TiO2-based photoelectrochemical platform.


    Ma, Weiguang; Wang, Lingnan; Zhang, Nan; Han, Dongxue; Dong, Xiandui; Niu, Li


    Herein, a novel photoelectrochemical platform with WS2/TiO2 composites as optoelectronic materials was designed for selective detection of o-diphenol and its derivatives without any biomolecule auxiliary. First, catechol was chosen as a model compound for the discrimination from resorcinol and hydroquinone; then several o-diphenol derivatives such as dopamine, caffeic acid, and catechin were also detected by employing this proposed photoelectrochemical sensor. Finally, the mechanism of such a selective detection has been elaborately explored. The excellent selectivity and high sensitivity should be attributed to two aspects: (i) chelate effect of adjacent double oxygen atoms in the o-diphenol with the Ti(IV) surface site to form a five/six-atom ring structure, which is considered as the key point for distinction and selective detection. (ii) This selected WS2/TiO2 composites with proper band level between WS2 and TiO2, which could make the photogenerated electron and hole easily separated and results in great improvement of sensitivity. By employing such a photoelectrochemical platform, practical samples including commercial clinic drugs and human urine samples have been successfully performed for dopamine detection. This biomolecule-free WS2/TiO2 based photoelectrochemical platform demonstrates excellent stability, reproducibility, remarkably convenient, and cost-effective advantages, as well as low detection limit (e.g., 0.32 μmol L(-1) for dopamine). It holds great promise to be applied for detection of o-diphenol kind species in environment and food fields. PMID:25844499

  6. Triton-X mediated interconnected nanowalls network of cadmium sulfide thin films via chemical bath deposition and their photoelectrochemical performance

    NASA Astrophysics Data System (ADS)

    Vanalakar, S. A.; Mali, S. S.; Jo, E. A.; Kim, J. Y.; Kim, J. H.; Patil, P. S.


    Thin films of cadmium sulfide (CdS) have been wet chemically deposited onto fluorine-doped tin oxide (FTO) coated conducting glass substrates by using non-ionic surfactant; Triton-X 100. An aqueous solution contains cadmium sulphate as a cadmium and thiourea as sulphur precursor. Ammonia used as a complexing agent. The results of measurements of the x-ray diffraction, Raman spectroscopy, optical spectroscopy, energy dispersive spectroscopy, scanning electron microscopy, Brunauer Emmett Teller (BET) surface areas and atomic force microscopy were used for the characterization of the films. These results revealed that the films are polycrystalline, consisting of CdS cubic phase. The films show a direct band gap with energy 2.39 eV. The films show interconnected nanowalls like morphology with well-defined surface area. Finally, the photoelectrochemical (PEC) performance of Triton-X mediated CdS thin film samples were studied. The sample shows photoelectrochemical (PEC) performance with maximum short circuit current density (Jsc) 1.71 mA/cm2 for larger area (1 cm2) solar cells.

  7. Optical and photoelectrochemical study of WTe2 single crystals

    NASA Astrophysics Data System (ADS)

    Desai, P. F.; Patel, D. D.; Bhavsar, D. N.; Jani, A. R.


    Single crystals of Tungsten Ditelluride (WTe2) having a layered structure grown by chemical vapor transport method using iodine as the transporting agent are studied here. The optical response of these crystals has been obtained by UV-Vis-NIR spectroscopy at room temperature. Results of optical spectra have been analyzed on the basis of three dimensional models. Photoelectrochemical (PEC) characterization of WTe 2 single crystals have been carried out. Photo response measurements were obtained at different intensities of light source to illuminate the photoanode. The effect of intensity in the efficiency of PEC solar cell has been studied. The implications of the results have been discussed.

  8. Nanostructure-based WO3 photoanodes for photoelectrochemical water splitting.


    Liu, Xien; Wang, Fengying; Wang, Qing


    Nanostructured WO(3) has been developed as a promising water-splitting material due to its ability of capturing parts of the visible light and high stability in aqueous solutions under acidic conditions. In this review, the fabrication, photocatalytic performance and operating principles of photoelectrochemical cells (PECs) for water splitting based on WO(3) photoanodes, with an emphasis on the last decade, are discussed. The morphology, dimension, crystallinity, grain boundaries, defect and separation, transport of photogenerated charges will also be mentioned as the impact factors on photocatalytic performance. PMID:22534756

  9. Orientation modulated charge transport in hematite for photoelectrochemical water splitting

    NASA Astrophysics Data System (ADS)

    Cai, Jiajia; Liu, Yinglei; Li, Song; Gao, Meiqi; Wang, Dunwei; Qin, Gaowu


    Hematite is currently considered one of the most promising photoanode materials for light-driven water splitting. The photoelectrochemical performance of hematite is limited by its low conductivity. In this work, we demonstrate that the conductivity of hematite films can be tuned by controlling the orientation of hematite crystals. By applying a high magnetic field (up to 10 T) during the drop-casting preparation, hematite films composed of single crystal particles show featured texture by promoting those particles alignment with (001) normal to the substrate. By enhancing the photocurrent densities with tuned hematite orientation, the current method provides an effective way for increasing the number of carriers that can reach the surface.

  10. Ultrathin planar hematite film for solar photoelectrochemical water splitting.


    Liu, Dong; Bierman, David M; Lenert, Andrej; Yu, Hai-Tong; Yang, Zhen; Wang, Evelyn N; Duan, Yuan-Yuan


    Hematite holds promise for photoelectrochemical (PEC) water splitting due to its stability, low-cost, abundance and appropriate bandgap. However, it suffers from a mismatch between the hole diffusion length and light penetration length. We have theoretically designed and characterized an ultrathin planar hematite/silver nanohole array/silver substrate photoanode. Due to the supported destructive interference and surface plasmon resonance, photons are efficiently absorbed in an ultrathin hematite film. Compared with ultrathin hematite photoanodes with nanophotonic structures, this photoanode has comparable photon absorption but with intrinsically lower recombination losses due to its planar structure and promises to exceed the state-of-the-art photocurrent of hematite photoanodes. PMID:26698797

  11. ZnO Nanocoral Structures for Photoelectrochemical Cells

    SciTech Connect

    Ahn, K. S.; Yan, Y.; Shet, S.; Jones, K.; Deutsch, T.; Turner, J.; Al-Jassim, M.


    We report on synthesis of a uniform and large area of a new form of ZnO nanocorals. These nanostructures can provide suitable electrical pathways for efficient carrier collection as well as large surface areas for the photoelectrochemical (PEC) cells. PEC devices made from these ZnO nanocoral structures demonstrate significantly enhanced photoresponse as compared to ZnO compact and nanorod films. Our results suggest that the nanocoral structures could be an excellent choice for nanomaterial-based applications such as dye-sensitized solar cells, electrochromic windows, and batteries.

  12. Plasmon-Enhanced Photoelectrochemical Water Splitting with Size-Controllable Gold Nanodot Arrays

    SciTech Connect

    Kim, HJ; Lee, SH; Upadhye, AA; Ro, I; Tejedor-Tejedor, MI; Anderson, MA; Kim, WB; Huber, GW


    Size-controllable Au nanodot arrays (50, 63, and 83 nm dot size) with a narrow size distribution (+/- 5%) were prepared by a direct contact printing method on an indium tin oxide (ITO) substrate. Titania was added to the Au nanodots using TiO2 sols of 2-3 nm in size. This created a precisely controlled Au nanodot with 110 nm of TiO2 overcoats. Using these precisely controlled nanodot arrays, the effects of Au nanodot size and TiO2 overcoats were investigated for photoelectrochemical water splitting using a three-electrode system with a fiber-optic visible light source. From UV-vis measurement, the localized surface plasmon resonance (LSPR) peak energy (ELSPR) increased and the LSPR line width (G) decreased with decreasing Au nanodot size. The generated plasmonic enhancement for the photoelectrochemical water splitting reaction increased with decreasing Au particle size. The measured plasmonic enhancement for light on/off experiments was 25 times for the 50 nm Au size and 10 times for the 83 nm Au nanodot size. The activity of each catalyst increased by a factor of 6 when TiO2 was added to the Au nanodots for all the samples. The activity of the catalyst was proportional to the quality factor (defined as Q = E-LSPR/Gamma) of the plasmonic metal nanostructure. The enhanced water splitting performance with the decreased Au nanodot size is probably due to more generated charge carriers (electron/hole pair) by local field enhancement as the quality factor increases.

  13. Final design review summary report for the TN-WHC cask and transportation system

    SciTech Connect

    Kee, A.T.


    This document represents comments generated from a review of Transnuclear`s Final Design Package distributed on December 10, 1996 and a review of the Final Design Analysis Report meeting held on December 17 & 18, 1996. The Final design describes desicn features and presents final analyses @j performed to fabricate and operate the system while meeting the Cask/Transportation Functions and Requirements, WHC-SD-SNF-FRD-011, Rev. 0 and specification WHC-S-0396, Rev. 1.


    EPA Science Inventory

    This document defines and classifies 338 Final Ecosystem Goods and Services (FEGS), each defined and uniquely numbered by a combination of environmental class or sub-class and a beneficiary category or sub-category. The introductory section provides the rationale and conceptual ...

  15. Nitrogen and cobalt co-doped zinc oxide nanowires - Viable photoanodes for hydrogen generation via photoelectrochemical water splitting

    NASA Astrophysics Data System (ADS)

    Patel, Prasad Prakash; Hanumantha, Prashanth Jampani; Velikokhatnyi, Oleg I.; Datta, Moni Kanchan; Hong, Daeho; Gattu, Bharat; Poston, James A.; Manivannan, Ayyakkannu; Kumta, Prashant N.


    Photoelectrochemical (PEC) water splitting has been considered as a promising and environmentally benign approach for efficient and economic hydrogen generation by utilization of solar energy. Development of semiconductor materials with low band gap, high photoelectrochemical activity and stability has been of particular interest for a viable PEC water splitting system. In this study, Co doped ZnO, .i.e., (Zn0.95Co0.05)O nanowires (NWs) was selected as the composition for further co-doping with nitrogen by comparing solar to hydrogen efficiency (SHE) of ZnO NWs with that of various compositions of (Zn1-xCox)O NWs (x = 0, 0.05, 0.1). Furthermore, nanostructured vertically aligned Co and N-doped ZnO, .i.e., (Zn1-xCox)O:N NWs (x = 0.05) have been studied as photoanodes for PEC water splitting. An optimal SHE of 1.39% the highest reported so far to the best of our knowledge for ZnO based photoanodes was obtained for the co-doped NWs, (Zn0.95Co0.05)O:N - 600 NWs generated at 600 °C in ammonia atmosphere. Further, (Zn0.95Co0.05)O:N-600 NWs exhibited excellent photoelectrochemical stability under illumination compared to pure ZnO NWs. These promising results suggest the potential of (Zn0.95Co0.05)O:N-600 NWs as a viable photoanode in PEC water splitting cell. Additionally, theoretical first principles study conducted explains the beneficial effects of Co and N co-doping on both, the electronic structure and the band gap of ZnO.

  16. Solar-Energy-Driven Photoelectrochemical Biosensing Using TiO2 Nanowires.


    Tang, Jing; Li, Jun; Da, Peimei; Wang, Yongcheng; Zheng, Gengfeng


    Photoelectrochemical sensing represents a unique means for chemical and biological detection, with foci of optimizing semiconductor composition and electronic structures, surface functionalization layers, and chemical detection methods. Here, we have briefly discussed our recent developments of TiO2 nanowire-based photoelectrochemical sensing, with particular emphasis on three main detection mechanisms and corresponding examples. We have also demonstrated the use of the photoelectrochemical sensing of real-time molecular reaction kinetic measurements, as well as direct interfacing of living cells and probing of cellular functions. PMID:25962650

  17. Multipurpose locator tag system : LDRD 65145 final report.

    SciTech Connect

    Greenway, Douglas Jr.; Schuster, Gary R.


    This report summarizes work performed to determine the capability of the Pinpoint Locator system, a commercial system designed and manufactured by RF Technologies. It is intended for use in finding people with locator badges in multi-story buildings. The Pinpoint system evaluated is a cell-based system, meaning it can only locate badges within an area bordered by its antennas.

  18. A Novel Photoelectrochemical Biosensor for Tyrosinase and Thrombin Detection

    PubMed Central

    Chen, Jiexia; Liu, Yifan; Zhao, Guang-Chao


    A novel photoelectrochemical biosensor for step-by-step assay of tyrosinase and thrombin was fabricated based on the specific interactions between the designed peptide and the target enzymes. A peptide chain with a special sequence which contains a positively charged lysine-labeled terminal, tyrosine at the other end and a cleavage site recognized by thrombin between them was designed. The designed peptide can be fixed on surface of the CdTe quantum dots (QDs)-modified indium-tin oxide (ITO) electrode through electrostatic attraction to construct the photoelectrochemical biosensor. The tyrosinase target can catalyze the oxidization of tyrosine by oxygen into ortho-benzoquinone residues, which results in a decrease in the sensor photocurrent. Subsequently, the cleavage site could be recognized and cut off by another thrombin target, restoring the sensor photocurrent. The decrease or increase of photocurrent in the sensor enables us to assay tyrosinase and thrombin. Thus, the detection of tyrosinase and thrombin can be achieved in the linear range from 2.6 to 32 μg/mL and from 4.5 to 100 μg/mL with detection limits of 1.5 μg/mL and 1.9 μg/mL, respectively. Most importantly, this strategy shall allow us to detect different classes of enzymes simultaneously by designing various enzyme-specific peptide substrates. PMID:26805846

  19. Photoelectrochemical Hydrogen Production Using New Combinatorial Chemistry Derived Materials

    SciTech Connect

    Jaramillo, Thomas F.; Baeck, Sung-Hyeon; Kleiman-Shwarsctein, Alan; Stucky, Galen D.; McFarland, Eric W.


    Solar photoelectrochemical water-splitting has long been viewed as one of the “holy grails” of chemistry because of its potential impact as a clean, renewable method of fuel production. Several known photocatalytic semiconductors can be used; however, the fundamental mechanisms of the process remain poorly understood and no known material has the required properties for cost effective hydrogen production. In order to investigate morphological and compositional variations in metal oxides as they relate to opto-electrochemical properties, we have employed a combinatorial methodology using automated, high-throughput, electrochemical synthesis and screening together with conventional solid-state methods. This report discusses a number of novel, high-throughput instruments developed during this project for the expeditious discovery of improved materials for photoelectrochemical hydrogen production. Also described within this report are results from a variety of materials (primarily tungsten oxide, zinc oxide, molybdenum oxide, copper oxide and titanium dioxide) whose properties were modified and improved by either layering, inter-mixing, or doping with one or more transition metals. Furthermore, the morphologies of certain materials were also modified through the use of structure directing agents (SDA) during synthesis to create mesostructures (features 2-50 nm) that increased surface area and improved rates of hydrogen production.

  20. A Novel Photoelectrochemical Biosensor for Tyrosinase and Thrombin Detection.


    Chen, Jiexia; Liu, Yifan; Zhao, Guang-Chao


    A novel photoelectrochemical biosensor for step-by-step assay of tyrosinase and thrombin was fabricated based on the specific interactions between the designed peptide and the target enzymes. A peptide chain with a special sequence which contains a positively charged lysine-labeled terminal, tyrosine at the other end and a cleavage site recognized by thrombin between them was designed. The designed peptide can be fixed on surface of the CdTe quantum dots (QDs)-modified indium-tin oxide (ITO) electrode through electrostatic attraction to construct the photoelectrochemical biosensor. The tyrosinase target can catalyze the oxidization of tyrosine by oxygen into ortho-benzoquinone residues, which results in a decrease in the sensor photocurrent. Subsequently, the cleavage site could be recognized and cut off by another thrombin target, restoring the sensor photocurrent. The decrease or increase of photocurrent in the sensor enables us to assay tyrosinase and thrombin. Thus, the detection of tyrosinase and thrombin can be achieved in the linear range from 2.6 to 32 μg/mL and from 4.5 to 100 μg/mL with detection limits of 1.5 μg/mL and 1.9 μg/mL, respectively. Most importantly, this strategy shall allow us to detect different classes of enzymes simultaneously by designing various enzyme-specific peptide substrates. PMID:26805846

  1. Nanostructured photoelectrochemical biosensor for highly sensitive detection of organophosphorous pesticides.


    Li, Xinyu; Zheng, Zhaozhu; Liu, Xuefeng; Zhao, Shenlong; Liu, Shaoqin


    A sensitive photoelectrochemical (PEC) biosensor for detection of organophosphorus pesticides (OPs) using the nanocomposite of CdSe@ZnS quantum dots (QDs) and graphene deposited on the ITO coated glass electrode as a photoactive electrode is presented. The integration of CdSe@ZnS/graphene nanocomposite with biomolecules acetylcholinesterase (AChE) as a biorecognition element yields a novel biosensing platform. Under visible light irradiation, the AChE-CdSe@ZnS/graphene nanocomposite can generate a stable photocurrent and the photocurrent is found to be inversely dependent on the concentration of OPs. Under the optimal experimental conditions, the photocurrents were proportional to the logarithm of paraoxon and dichlorvos within the concentration range of 10(-12)-10(-6) M. The detection limits (LOD) of the proposed biosensor for paraoxon and dichlorvos are as low as 10(-14) M and 10(-12) M. The photoelectrochemical biosensor shows good sensitivity, reproducibility, stability, and could be successfully applied to detection of OPs in real fruit samples. PMID:25173731

  2. Power plant system assessment. Final report. SP-100 Program

    SciTech Connect

    Anderson, R.V.; Atkins, D.F.; Bost, D.S.; Berman, B.; Clinger, D.A.; Determan, W.R.; Drucker, G.S.; Glasgow, L.E.; Hartung, J.A.; Harty, R.B.


    The purpose of this assessment was to provide system-level insights into 100-kWe-class space reactor electric systems. Using these insights, Rockwell was to select and perform conceptual design studies on a ''most attractive'' system that met the preliminary design goals and requirements of the SP-100 Program. About 4 of the 6 months were used in the selection process. The remaining 2 months were used for the system conceptual design studies. Rockwell completed these studies at the end of FY 1983. This report summarizes the results of the power plant system assessment and describes our choice for the most attractive system - the Rockwell SR-100G System (Space Reactor, 100 kWe, Growth) - a lithium-cooled UN-fueled fast reactor/Brayton turboelectric converter system.

  3. Framework for Adaptable Operating and Runtime Systems: Final Project Report

    SciTech Connect

    Patrick G. Bridges


    In this grant, we examined a wide range of techniques for constructing high-performance con gurable system software for HPC systems and its application to DOE-relevant problems. Overall, research and development on this project focused in three specifc areas: (1) software frameworks for constructing and deploying con gurable system software, (2) applcation of these frameworks to HPC-oriented adaptable networking software, (3) performance analysis of HPC system software to understand opportunities for performance optimization.

  4. Understanding Equilibrium: The Study of Complex Systems. Final Project Report.

    ERIC Educational Resources Information Center

    Duckworth, Eleanor; And Others

    The Educational Technology Center (ETC) Complex Systems Project was initiated to explore ways of using computers to help students understand systems which have often proven too complex for most high school students to understand. Preliminary work concentrated on the cognitive processes involved in modeling simple systems. This paper describes an…

  5. A System for Inter-Library Communication (SILC). Final Report.

    ERIC Educational Resources Information Center

    Hayes, R. M.

    A study was made of the use of time-sharing computer systems as a means of communication, accounting, message switching, and referral in a System for Inter-Library Communication (SILC). The purpose of the study was to develop data on which to evaluate the feasibility of such a system; the results are reported in terms of four issues: technical…

  6. The Print and Computer Enlargement System--PACE. Final Report.

    ERIC Educational Resources Information Center

    Morford, Ronald A.

    The Print and Computer Enlargement (PACE) System is being designed as a portable computerized reading and writing system that enables a low-vision person to read regular print and then create and edit text using large-print computerized output. The design goal was to develop a system that: weighed no more than 12 pounds so it could be easily…

  7. Recalibrating the BC Transfer System: Approved Final Report

    ERIC Educational Resources Information Center

    British Columbia Council on Admissions and Transfer, 2006


    In November 2005, the BC Council on Admissions and Transfer launched a consultation entitled Recalibrating the BC Transfer System with the institutional members of the BC Transfer System and other interested parties. This consultation was motivated in large part by significant changes in the BC post-secondary system over the last decade, and…

  8. INFeRS: Interactive Numeric Files Retrieval System. Final Report.

    ERIC Educational Resources Information Center

    Chiang, Katherine; And Others

    In 1988 Mann Library at Cornell University proposed to develop a computer system that would support interactive access to significant electronic files in agriculture and the life sciences. This system was titled the Interactive Numeric Files Retrieval System (INFeRS). This report describes how project goals were met and it presents the project's…

  9. Photovoltaic-system costing-methodology development. Final report

    SciTech Connect

    Not Available


    Presented are the results of a study to expand the use of standardized costing methodologies in the National Photovoltaics Program. The costing standards, which include SAMIS for manufacturing costs and M and D for marketing and distribution costs, have been applied to concentrator collectors and power-conditioning units. The M and D model was also computerized. Finally, a uniform construction cost-accounting structure was developed for use in photovoltaic test and application projects. The appendices contain example cases which demonstrate the use of the models.

  10. Technology verification phase. Dynamic isotope power system. Final report

    SciTech Connect

    Halsey, D.G.


    The Phase I requirements of the Kilowatt Isotope Power System (KIPS) program were to make a detailed Flight System Conceptual Design (FSCD) for an isotope fueled organic Rankine cycle power system and to build and test a Ground Demonstration System (GDS) which simulated as closely as possible the operational characteristics of the FSCD. The activities and results of Phase II, the Technology Verification Phase, of the program are reported. The objectives of this phase were to increase system efficiency to 18.1% by component development, to demonstrate system reliability by a 5000 h endurance test and to update the flight system design. During Phase II, system performance was improved from 15.1% to 16.6%, an endurance test of 2000 h was performed while the flight design analysis was limited to a study of the General Purpose Heat Source, a study of the regenerator manufacturing technique and analysis of the hardness of the system to a laser threat. It was concluded from these tests that the GDS is basically prototypic of a flight design; all components necessary for satisfactory operation were demonstrated successfully at the system level; over 11,000 total h of operation without any component failure attested to the inherent reliability of this type of system; and some further development is required, specifically in the area of performance. (LCL)

  11. Genetic algorithm testbed for expert system testing. Final report

    SciTech Connect

    Roache, E.


    In recent years, the electric utility industry has developed advisory and control software that makes use of expert system technology. The validation of the underlying knowledge representation in these expert systems is critical to their success. Most expert systems currently deployed have been validated by certifying that the expert system provides appropriate conclusions for specific test cases. While this type of testing is important, it does not test cases where unexpected inputs are presented to the expert system and potential errors are exposed. Exhaustive testing is not typically an option due to the complexity of the knowledge representation and the combinatorial effects associated with checking all possible inputs through all possible execution paths. Genetic algorithms are general purpose search techniques modeled on natural adaptive systems and selective breeding methods. Genetic algorithms have been used successfully for parameter optimization and efficient search. The goal of this project was to confirm or reject the hypothesis that genetic algorithms (GAs) are useful in expert system validation. The GA system specifically targeted errors in the study`s expert system that would be exposed by unexpected input cases. The GA system found errors in the expert system and the hypothesis was confirmed. This report describes the process and results of the project.

  12. Linker-free deposition and adhesion of Photosystem I onto nanostructured TiO2 for biohybrid photoelectrochemical cells.


    Shah, Vivek B; Henson, William R; Chadha, Tandeep S; Lakin, Gerard; Liu, Haijun; Blankenship, Robert E; Biswas, Pratim


    Photosystem I (PSI) from oxygenic photosynthetic organisms is an attractive sensitizer for nano-biohybrid solar cells as it has a combined light-harvesting and reaction center in one protein complex and operates at a quantum yield close to one in biological systems. Using a linker-free deposition technique enabled by an electrospray system, PSI was coupled to 1-D nanostructured titanium dioxide thin films to fabricate an electrode for a photoelectrochemical cell. After deposition, the surfactant in the PSI aggregate was dissolved in the surfactant-free electrolyte, ensuring that partly hydrophobic PSI was not resuspended and stayed in contact with titanium dioxide. A maximum current density of 4.15 mA cm(-2) was measured after 10 min of electrospray deposition, and this is the highest current density reported so far for PSI-based photoelectrochemical cells. The high current is attributed to 1D nanostructure of titanium dioxide and orientation of the PSI onto the surface, which allows easy transfer of electrons. PMID:25540979

  13. Improved performance of InSe-based photoelectrochemical cells by means of a selective (photo)electrochemical etching

    NASA Astrophysics Data System (ADS)

    Tenne, R.; Theys, B.; Rioux, J.; Levy-Clement, C.


    It is shown that the performance of photoelectrochemical cells based on the lamellar material InSe can be considerably improved by means of a selective (photo)electrochemical etching. Whereas the cleavage Van de Waals plane (⊥ to c axis) shows little improvement, the photcurrent in the ∥ face (parallel to the c axis) is doubled (30 mA cm-2 under AM1 illumination). For n-type InSe a reverse bias (+1.5 V versus standard calomel electrode SCE) was employed during the photoetching, p-InSe electrodes were electrochemically etched by applying a forward bias (+1.5 V). In both cases, surface holes carry out the selective corrosion of the semiconductor surface which is another manifestation for the asymmetry played by holes and electrons on semiconductor surfaces. It is hoped that this finding will pave the way for the construction of high-efficiency solar cells based on a thin film made of lamellar materials.

  14. Dense layers of vertically oriented WO 3 crystals as anodes for photoelectrochemical water oxidation

    SciTech Connect

    Qin, Dong-Dong; Tao, Chun-Lan; Friesen, Stuart A.; Wang, Tsing-Hai; Varghese, Oomman K.; Bao, Ning-Zhong; Yang, Zheng-Yin; Mallouk, Thomas E.; Grimes, Craig A.


    Films of crystalline WO₃ nanosheets oriented perpendicular to tungsten substrates were grown by a surfactant-free hydrothermal method, followed by sintering. The films exhibit photoelectrochemical oxygen evolution at low overpotential.

  15. In situ formation of p-n junction: a novel principle for photoelectrochemical sensor and its application for mercury(II) ion detection.


    Wang, Guang-Li; Liu, Kang-Li; Dong, Yu-Ming; Li, Zai-Jun; Zhang, Chi


    The discovery and development of photoelectrochemical sensors with novel principles are of great significance to realize sensitive and low-cost detection. In this paper, a new photoelectrochemial sensor based on the in situ formation of p-n junction was designed and used for the accurate determination of mercury(II) ions. Cysteine-capped ZnS quantum dots (QDs) was assembled on the surface of indium tin oxide (ITO) electrode based on the electrostatic interaction between Poly(diallyldimethylammonium chloride) (PDDA) and Cys-capped ZnS QDs. The in situ formation of HgS, a p-type semiconductor, on the surface of ZnS facilitated the charge carrier transport and promoted electron-hole separation, triggered an obviously enhanced anodic photocurrent of Cys-capped ZnS QDs. The formation of p-n junction was confirmed by P-N conductive type discriminator measurements and current-voltage (I-V) curves. The photoelectrochemical method was used for the sensing of trace mercuric (II) ions with a linear concentration of 0.01 to 10.0 µM and a detection limit of 4.6×10(-9)mol/L. It is expected that the present study can serve as a foundation to the application of p-n heterojunction to photoelectrochemical sensors and it might be easily extended to more exciting sensing systems by photoelectrochemistry. PMID:24832992

  16. Research on photoelectrochemical cells based on CdSe, CdSe/sub 1-x/Te/sub x/ and other photoelectrode materials

    SciTech Connect

    Wallace, W L


    Research on electrochemical photovoltaic cells incorporating thin film n-CdSe and n-CdSe/sub 1-x/Te/sub x/ photoanodes has resulted in efficiencies up to 7.5% using small area electrodes in polysulfide electrolytes. Efficiencies close to 10% can be achieved using alternate electrolytes in significantly less stable systems. The major limitations on the efficiency of II-VI photoelectrochemical cells are associated with the open circuit voltage and the fill factor. Research on CuInSe/sub 2/ electrochemical photovoltaic cells has resulted in efficiencies up to 11.7% using single crystal n-CuInSe/sub 2/ photoanodes in aqueous electrolytes. The n-CuInSe/sub 2/ surface and the electrolyte have been optimized to produce a highly stable semiconductor/electrolyte junction. A review will also be given on the status of photoelectrochemical storage cell research. In situ photoelectrochemical measurement techniques have been used to probe the semiconductor/electrolyte interface and have been used to support the characterization of semiconductor materials for solid state photovoltaic applications.

  17. Nb doped TiO2 nanotubes for enhanced photoelectrochemical water-splitting.


    Das, Chittaranjan; Roy, Poulomi; Yang, Min; Jha, Himendra; Schmuki, Patrik


    Nanostructured titanium dioxide is one of the classic materials for photoelectrochemical water splitting. In the present work we dope TiO(2) nanotube anodes. For this, various low concentration bulk-Nb-doped TiO(2) nanotube layers were grown by self-organizing anodization of Ti-Nb alloys. At Nb-contents around 0.1 at%, and after an adequate heat-treatment, a strongly increased and stable photoelectrochemical water-splitting rate is obtained. PMID:21761039

  18. Regular Class Participation System (RCPS). A Final Report.

    ERIC Educational Resources Information Center

    Ferguson, Dianne L.; And Others

    The Regular Class Participation System (RCPS) project attempted to develop, implement, and validate a system for placing and maintaining students with severe disabilities in general education classrooms, with a particular emphasis on achieving both social and learning outcomes for students. A teacher-based planning strategy was developed and…

  19. Airborne Electro-Optical Sensor Simulation System. Final Report.

    ERIC Educational Resources Information Center

    Hayworth, Don

    The total system capability, including all the special purpose and general purpose hardware comprising the Airborne Electro-Optical Sensor Simulation (AEOSS) System, is described. The functional relationship between hardware portions is described together with interface to the software portion of the computer image generation. Supporting rationale…

  20. A Technical Index of Interactive Information Systems. Final Report.

    ERIC Educational Resources Information Center

    Fife, Dennis W.; And Others

    The technical features and operational status of interactive information systems, i.e. those providing a conversational usage mode to a non-programer through a data terminal device, are reviewed. The review is designed to aid information specialists in the state-of-the-art assessments preparatory to a detailed system selection procedure. It…

  1. Employability Competency System. California Statewide Results. Final Report.

    ERIC Educational Resources Information Center

    Eguez, Jane; And Others

    A demographic and educational profile was constructed of learners enrolled in California employment training programs. Summary data were derived from 47,318 Employability Competency System (ECS) Appraisal answer sheets received by the Comprehensive Adult Student Assessment System (CASAS) office from 1987 through 1990. ECS provides reading, math,…

  2. Mirror fusion test facility magnet system. Final design report

    SciTech Connect

    Henning, C.D.; Hodges, A.J.; VanSant, J.H.; Dalder, E.N.; Hinkle, R.E.; Horvath, J.A.; Scanlan, R.M.; Shimer, D.W.; Baldi, R.W.; Tatro, R.E.


    Information is given on each of the following topics: (1) magnet description, (2) superconducting manufacture, (3) mechanical behavior of conductor winding, (4) coil winding, (5) thermal analysis, (6) cryogenic system, (7) power supply system, (8) structural analysis, (9) structural finite element analysis refinement, (10) structural case fault analysis, and (11) structural metallurgy. (MOW)

  3. Bifurcation and chaos in power systems: A survey. Final report

    SciTech Connect

    Varaiya, P.; Wu, F.; Chiang, H.D.


    The literature dealing with bifurcation and chaos in electric power systems is surveyed. A brief discussion of relevant mathematical concepts and results is included in order to make the presentation self-contained and readily accessible. The objective is to determine the extent and significance of power system behavior that can be understood by dynamic models exhibiting bifurcation and chaotic motion. Bifurcation denotes a qualitative change in system behavior. The study is divided into three parts dealing with static bifurcations, Hopf bifurcations, and chaos. Static bifurcation occurs when two or more equilibrium points coincide. Hopf bifurcation occurs when a periodic oscillation emerges from a stable equilibrium. These are both examples of local bifurcation - they are determined by the system behavior in a neighborhood of the equilibrium. Chaos emerges from a global bifurcation - a non-local change in the phase portrait of tile system. The following conclusions are reached. Even the simplest models of power systems exhibit both local and global bifurcations. Local bifurcations occur because power flow equations have multiple solutions. In models that only incorporate real power flow, the capacity of transmission systems is so large that local bifurcations although present are unlikely to be practically significant. However, in models where voltage is determined by reactive power flows, local bifurcations can dramatically shrink the stability region. These bifurcations may explain ``voltage collapse``. The simplest models also exhibit chaotic behavior. However, for analytical convenience, chaos has mostly been investigated in systems with unrealistic parameter values.

  4. A Feature Analysis of Interactive Retrieval Systems. Final Report.

    ERIC Educational Resources Information Center

    Martin, Thomas H.

    The command language features of 11 on-line information retrieval systems are presented in terms of the functional needs of a searcher sitting at a terminal. Functional areas considered are: becoming familiar with the system, receiving help when in trouble, regulating usage, selecting a data base, formulating simple queries, expressing single…

  5. Quality Control Study of the GSL Reinsurance System. Final Report.

    ERIC Educational Resources Information Center

    Advanced Technology, Inc., Reston, VA.

    A quality control plan for the U.S. Department of Education's Guaranteed Student Loan (GSL) reinsurance process was developed. To identify existing errors, systems documentation and past analyses of the reinsurance system were analyzed, and interviews were conducted. Corrective actions were proposed, and a quality control checklist was developed…

  6. Personnel Evaluation Systems in AISD, 1983-84, Final Report.

    ERIC Educational Resources Information Center

    Austin Independent School District, TX. Office of Research and Evaluation.

    This report summarizes the Austin Independent School District's Professional Personnel Evaluation System ratings for 1984, and presents findings on teacher and administrator satisfaction with the evaluation system. The average teacher ratings in 46 competency areas were similar to the 1983 ratings. Sixty-nine percent of the teachers received high…

  7. Windjammer solar-water-heating system. Final technical report

    SciTech Connect

    Windham, J.R.


    The results of the Windjammer Solar-Water-Heating System tests showed that it was not as an efficient system as a comparable conventional system for converting solar energy into heat energy. However, it was determined that the innovative mode used less electric back-up energy for water heating. Reduced fossil fuel energy consumption being the ultimate objective of a solar water heating, the principle employed has been shown to be a workable energy saving concept. The differential mode of temperature control emerged as the more efficient mode of operation for the innovative system and under comparable conditions is projected to be nearly equivalent to the conventional solar system. Although the concept has proven workable, the costs feasible, and the potential for considereable improvements exists, additional research and development is needed to advance the design into its most practical application.

  8. Standards for photovoltaic energy conversion systems. Final report

    SciTech Connect

    Schafft, H. A.


    This report provides the results of a search for existing domestic standards and related documents for possible application in the development of a standards base for photovoltaic energy conversion systems. The search resulted in locating about 150 test methods, recommended practices, standards, solar-thermal performance criteria, and other standards-related documents. They are listed by topic areas in the appendix. The listing was prepared to assist those involved in developing performance criteria for photovoltaic systems and in identifying methods to test system performance against these criteria. It is clear from the results of the search that few standards are directly applicable to terrestrial solar photovoltaic systems and that much standards development is required to support the commercialization of such systems.

  9. Advanced Caution and Warning System, Final Report - 2011

    NASA Technical Reports Server (NTRS)

    Spirkovska, Lilly; Aaseng, Gordon; Iverson, David; McCann, Robert S.; Robinson, Peter; Dittemore, Gary; Liolios, Sotirios; Baskaran, Vijay; Johnson, Jeremy; Lee, Charles; Ossenfort, John; Dalal, Mike; Fry, Chuck; Garner, Larry


    The work described in this report is a continuation of the ACAWS work funded in fiscal year (FY) 2010 under the Exploration Technology Development Program (ETDP), Integrated Systems Health Management (ISHM) project. In FY 2010, we developed requirements for an ACAWS system and vetted the requirements with potential users via a concept demonstration system. In FY 2011, we developed a working prototype of aspects of that concept, with placeholders for technologies to be fully developed in future phases of the project. The objective is to develop general capability to assist operators with system health monitoring and failure diagnosis. Moreover, ACAWS was integrated with the Discrete Controls (DC) task of the Autonomous Systems and Avionics (ASA) project. The primary objective of DC is to demonstrate an electronic and interactive procedure display environment and multiple levels of automation (automatic execution by computer, execution by computer if the operator consents, and manual execution by the operator).

  10. Operational testing of intelligent rail lubrication system. Final report

    SciTech Connect

    Kumar, S.


    This IDEA project designs, builds, and demonstrates an automated, computer-controlled onboard intelligent system for applying new environmentally safe and consumable lubricants for rail systems. The IDEA product is to be operationally tested in a commuter rail system (METRA) for providing controlled lubrication on rails and wheel in an environmentally safe way. The lubricant applied to the rail will reduce friction between the wheel and rail and is expected to provide significant benefits in maintenance, safety, and overall economic efficiency. Progressive development of a rail lubrication system for US railroads indicates potential major benefits including reduction in wheel wear, rail wear, and track maintenance costs. Significant benefits transferable to commuter rail and high-speed transit systems are expected as well.

  11. Georgia Power Corporate Headquarters solar system. Final construction status report

    SciTech Connect

    Not Available


    The 24-story high-rise and the three story low-rise consumes about 50,000 Btu/ft/sup 2/-yr (including computer process loads). The solar system will provide about 18.6% of the heating and cooling loads. There are 23,712 square feet of parabolic trough collectors which collect a maximum of 3.4 million Btu/hr. Past experience and advice from previous DOE projects lead to the use of a treated water recirculation freeze protection system in lieu of an ethylene glycol system. The project uses a unique version of the Delavan tracker in order to perform properly in the southeastern climate. Conclusions reached during this project include: (1) even with performance type specifications, detailed specifications for intergration into building mechanical systems are required, (2) reaction time of the computer control system can inhibit the collector tracking system operation, (3) extreme care must be used in a large system design to insure balanced flow, (4) the Delavan tracker can be altered to operate more efficiently, (5) the GPC solar system is providing slightly less than the predicted amount of energy, due to apparently higher than expected parasitic losses, (6) total available direct radiation appears to be less than predicted for summer months, (7) the electrical hardware at the collector motors requires more maintenance than expected because of the harsh environment at their locations, (8) the control logic has to be altered to deal with hot hazy days, and (9) there are a number of improvements needed to make the system more maintenance free.

  12. Intergovernmental Advanced Stationary PEM Fuel Cell System Demonstration Final Report

    SciTech Connect

    Rich Chartrand


    A program to complete the design, construction and demonstration of a PEMFC system fuelled by Ethanol, LPG or NG for telecom applications was initiated in October 2007. Early in the program the economics for Ethanol were shown to be unfeasible and permission was given by DOE to focus on LPG only. The design and construction of a prototype unit was completed in Jun 2009 using commercially available PEM FC stack from Ballard Power Systems. During the course of testing, the high pressure drop of the stack was shown to be problematic in terms of control and stability of the reformer. Also, due to the power requirements for air compression the overall efficiency of the system was shown to be lower than a similar system using internally developed low pressure drop FC stack. In Q3 2009, the decision was made to change to the Plug power stack and a second prototype was built and tested. Overall net efficiency was shown to be 31.5% at 3 kW output. Total output of the system is 6 kW. Using the new stack hardware, material cost reduction of 63% was achieved over the previous Alpha design. During a November 2009 review meeting Plug Power proposed and was granted permission, to demonstrate the new, commercial version of Plug Power's telecom system at CERL. As this product was also being tested as part of a DOE Topic 7A program, this part of the program was transferred to the Topic 7A program. In Q32008, the scope of work of this program was expanded to include a National Grid demonstration project of a micro-CHP system using hightemperature PEM technology. The Gensys Blue system was cleared for unattended operation, grid connection, and power generation in Aug 2009 at Union College in NY state. The system continues to operate providing power and heat to Beuth House. The system is being continually evaluated and improvements to hardware and controls will be implemented as more is learned about the system's operation. The program is instrumental in improving the efficiency and

  13. Field investigation of FGD system chemistry. Final report

    SciTech Connect

    Litherland, S.T.; Colley, J.D.; Glover, R.L.; Maller, G.; Behrens, G.P.


    Three full-scale wet limestone FGD systems were investigated to gain a better understanding of FGD system operation and chemistry. The three plants which participated in the program were South Mississippi Electric Power Association's R. D. Morrow Station, Colorado-Ute Electric Association's Craig Station, and Central Illinois Light Company's Duck Creek Station. Each FGD system was characterized with respect to SO/sub 2/ removal, liquid and solid phase chemistry, and calcium sulfite and calcium sulfate relative saturation. Mist eliminator chemistry and performance were documented at Morrow and Duck Creek. Solutions to severe mist eliminator scaling and pluggage were demonstrated at Duck Creek. A technical and econ

  14. Automation of a gated-pipe irrigation system. Final report

    SciTech Connect

    Manges, H.L.; Blume, H.R.; Matteson, D.K.; Butler, K.G.


    An existing gated-pipe system was automated by controlling flow into short segments of gated pipe with flow-control valves. Irrigation controllers and a microcomputer both operated the flow-control valves automatically by radio controls. The irrigation controllers and the microcomputer successfully operated the system. Although both can provide cutback-head irrigation, the microcomputer is capable of more flexible system operation. Radio controls sold for controlling model airplanes did not give reliable service when operated continuously in an irrigated field. Operation of the flo-control valves was satisfactory.

  15. HARNESS: Heterogeneous Adaptable Reconfigurable Networked Systems. Final Progress Report

    SciTech Connect

    Fagg, G. E.


    HARNESS was proposed as a system that combined the best of emerging technologies found in current distributed computing research and commercial products into a very flexible, dynamically adaptable framework that could be used by applications to allow them to evolve and better handle their execution environment. The HARNESS system was designed using the considerable experience from previous projects such as PVM, MPI, IceT and Cumulvs. As such, the system was designed to avoid any of the common problems found with using these current systems, such as no single point of failure, ability to survive machine, node and software failures. Additional features included improved intercomponent connectivity, with full support for dynamic down loading of addition components at run-time thus reducing the stress on application developers to build in all the libraries they need in advance.

  16. Dynamic analysis of the American Maglev system. Final report

    SciTech Connect

    Seda-Sanabria, Y.; Ray, J.C.


    Understanding the dynamic interaction between a magnetic levitated (Maglev) vehicle and its supporting guideway is essential in the evaluation of the performance of such a system. This interacting coupling, known as vehicle/guideway interaction (VGI), has a significant effect on system parameters such as the required magnetic suspension forces and gaps, vehicular ride quality, and guideway deflections and stresses. This report presents the VGI analyses conducted on an actual Maglev system concept definition (SCD), the American Maglev SCD, using a linear-elastic finite-element (FE) model. Particular interest was focused on the comparison of the ride quality of the vehicle, using two different suspension systems, and their effect on the guideway structure. The procedure and necessary assumptions in the modeling are discussed.

  17. Improved Controls for Fusion RF Systems. Final technical report

    SciTech Connect

    Casey, Jeffrey A.


    We have addressed the specific requirements for the integrated systems controlling an array of klystrons used for Lower Hybrid Current Drive (LHCD). The immediate goal for our design was to modernize the transmitter protection system (TPS) for LHCD on the Alcator C-Mod tokamak at the MIT Plasma Science and Fusion Center (MIT-PSFC). Working with the Alcator C-Mod team, we have upgraded the design of these controls to retrofit for improvements in performance and safety, as well as to facilitate the upcoming expansion from 12 to 16 klystrons. The longer range goals to generalize the designs in such a way that they will be of benefit to other programs within the international fusion effort was met by designing a system which was flexible enough to address all the MIT system requirements, and modular enough to adapt to a large variety of other requirements with minimal reconfiguration.

  18. Center for Advanced Biofuel Systems (CABS) Final Report

    SciTech Connect

    Kutchan, Toni M.


    One of the great challenges facing current and future generations is how to meet growing energy demands in an environmentally sustainable manner. Renewable energy sources, including wind, geothermal, solar, hydroelectric, and biofuel energy systems, are rapidly being developed as sustainable alternatives to fossil fuels. Biofuels are particularly attractive to the U.S., given its vast agricultural resources. The first generation of biofuel systems was based on fermentation of sugars to produce ethanol, typically from food crops. Subsequent generations of biofuel systems, including those included in the CABS project, will build upon the experiences learned from those early research results and will have improved production efficiencies, reduced environmental impacts and decreased reliance on food crops. Thermodynamic models predict that the next generations of biofuel systems will yield three- to five-fold more recoverable energy products. To address the technological challenges necessary to develop enhanced biofuel systems, greater understanding of the non-equilibrium processes involved in solar energy conversion and the channeling of reduced carbon into biofuel products must be developed. The objective of the proposed Center for Advanced Biofuel Systems (CABS) was to increase the thermodynamic and kinetic efficiency of select plant- and algal-based fuel production systems using rational metabolic engineering approaches grounded in modern systems biology. The overall strategy was to increase the efficiency of solar energy conversion into oils and other specialty biofuel components by channeling metabolic flux toward products using advanced catalysts and sensible design:1) employing novel protein catalysts that increase the thermodynamic and kinetic efficiencies of photosynthesis and oil biosynthesis; 2) engineering metabolic networks to enhance acetyl-CoA production and its channeling towards lipid synthesis; and 3) engineering new metabolic networks for the

  19. Windpowered irrigation system for small pecan orchards. Final report

    SciTech Connect

    Goulden, D.R.


    A solution to the high installation and maintenance costs for small-orchard irrigation lies in the use of the windmill and a gravity-flow distribution system. Applying windpower for pumping and distributing water for irrigation of small pecan orchards is now economically feasible in many areas where pecans are grown. Because of its constant, moderate wind speeds, the central Oklahoma region lends itself well to such a system.

  20. Solar heating system installed at Jackson, Tennessee. Final report

    SciTech Connect


    The solar energy heating system installed at the Coca-Cola Bottling Works in Jackson, Tennessee is described. The system consists of 9480 square feet of Owens-Illinois evacuated tubular solar collectors with attached specular cylindrical reflectors and will provide space heating for the 70,000 square foot production building in the winter, and hot water for the bottle washing equipment the remainder of the year. Component specifications and engineering drawings are included. (WHK)

  1. Wetland plant communities, Galveston Bay system. Final report

    SciTech Connect

    White, W.A.; Paine, J.G.


    The report is the culmination of a field investigation of wetland plant communities, and is one phase of the project, Trends and Status of Wetland and Aquatic Habitats of the Galveston Bay System, Texas, sponsored by the Galveston Bay National Estuary Program. For purpose of the topical report, wetlands are defined and classified in terms of more classical definitions, for example, salt, brackish, and fresh marshes, in accordance with project requirements. More than 150 sites were examined in the Galveston Bay system.

  2. Final Report for the Virtual Reliability Realization System LDRD

    SciTech Connect



    Current approaches to reliability are not adequate to keep pace with the need for faster, better and cheaper products and systems. This is especially true in high consequence of failure applications. The original proposal for the LDRD was to look at this challenge and see if there was a new paradigm that could make reliability predictions, along with a quantitative estimate of the risk in that prediction, in a way that was faster, better and cheaper. Such an approach would be based on the underlying science models that are the backbone of reliability predictions. The new paradigm would be implemented in two software tools: the Virtual Reliability Realization System (VRRS) and the Reliability Expert System (REX). The three-year LDRD was funded at a reduced level for the first year ($120K vs. $250K) and not renewed. Because of the reduced funding, we concentrated on the initial development of the expertise system. We developed an interactive semiconductor calculation tool needed for reliability analyses. We also were able to generate a basic functional system using Microsoft Siteserver Commerce Edition and Microsoft Sequel Server. The base system has the capability to store Office documents from multiple authors, and has the ability to track and charge for usage. The full outline of the knowledge model has been incorporated as well as examples of various types of content.

  3. Development of a polystyrene insulation system. Final technical progress report

    SciTech Connect

    Rupert, J.G.


    An adhesive coating system for loose fill polystyrene materials was developed as a product primarily for retrofit insulation of residential buildings that would neither shrink nor settle. Several problems with the coated system including flammability and shrinkage led us to consider an alternative system in which an expanded rock product called perlite was considered as an alternative to polystyrene. The primary problems with perlite are that it is very expensive and the coated structure is extremely brittle. A very attractive commercial market for retrofit insulation using either polystyrene beads or shredded polystyrene was identified. Specifically, it was demonstrated that commercial cement block buildings can be reinsulated by filling the cores of the cement blocks with a payback period of three years. With additional development, it appears that the payback period can be reduced to 2 years at present natural gas prices. The potential market for a commercial system of this kind was analyzed and determined to be on the order of ten billion dollars nationally. The estimated potential energy savings are on order of one quad. At this time, the system is being redesigned to handle commercial buildings which have areas on the order of several hundred thousand square feet. Test marketing of the present system is in progress.

  4. Photoelectrochemical and photocatalytic properties of biphasic organic p- and n-type semiconductor nanoparticles fabricated by a reprecipitation process.


    Zhang, Shuai; Sakai, Ryohei; Abe, Toshiyuki; Iyoda, Tomokazu; Norimatsu, Takayoshi; Nagai, Keiji


    The visible-light-responsive photoelectrochemical and photocatalytic properties of nanoparticles of C(60), partially hydrolyzed aluminum phthalocyanine chloride (denoted as AlPc), and a composite of the two are reported. The three types of nanoparticles were obtained through a reprecipitation method from N-methyl-2-pyrrolidone solutions of C(60), aluminum phthalocyanine chloride (AlPcCl), and their mixture, respectively. The nanoparticle composite's ultraviolet-visible absorption, diffuse-reflectance and Fourier transform IR spectra, X-ray diffraction pattern, and scanning electron microscopy image are all similar to the sum of those of the C(60) and AlPc particles, respectively. The nano-ordered composite exhibits p/n junctionlike photoelectrochemical characteristics, which were investigated in comparison with those of vapor-deposited C(60) (n-type), AlPcCl (p-type), C(60)/AlPcCl (n/p), and AlPcCl/C(60) (p/n) electrodes. The nanoparticle composite further shows photocatalytic activity for the decomposition of trimethylamine to carbon dioxide in a suspension system. PMID:21604785

  5. The fabrication of In2O3/In2S3/Ag nanocubes for efficient photoelectrochemical water splitting.


    Xu, Rui; Li, Haohua; Zhang, Wenwen; Yang, Zepeng; Liu, Guiwu; Xu, Ziwei; Shao, Haicheng; Qiao, Guanjun


    In this work, for the first time, a three-component In2O3/In2S3/Ag nanocomposite heterostructured photoanode is prepared on a F-doped SnO2 (FTO) glass substrate. The three-component photoanode exhibits significantly enhanced photoelectrochemical properties compared with the single-component (In2O3) and two-component (In2O3/In2S3 or In2O3/Ag) systems. Ag nanoparticles deposited on the surface of In2O3/In2S3 nanocubes can facilitate the separation of photogenerated charge carriers and enhance the absorption of visible light. In I-V curves, the In2O3/In2S3/Ag photoanode generates a remarkable photocurrent density of 8.75 mA cm(-2) (at 0 V vs. SCE), which is higher than those of the two-component In2O3/In2S3 (4.47 mA cm(-2)) and In2O3/Ag (3.50 mA cm(-2)). Furthermore, it also gives efficiency as high as 67% around 350 nm in the incident photon to electron conversion efficiency (IPCE) spectrum. These results open up a promising avenue for the design and fabrication of novel heterojunctions for photoelectrochemical water splitting. PMID:26725370

  6. Smart Infrared Inspection System Field Operational Test Final Report

    SciTech Connect

    Siekmann, Adam; Capps, Gary J; Franzese, Oscar; Lascurain, Mary Beth


    The Smart InfraRed Inspection System (SIRIS) is a tool designed to assist inspectors in determining which vehicles passing through the SIRIS system are in need of further inspection by measuring the thermal data from the wheel components. As a vehicle enters the system, infrared cameras on the road measure temperatures of the brakes, tires, and wheel bearings on both wheel ends of commercial motor vehicles (CMVs) in motion. This thermal data is then presented to enforcement personal inside of the inspection station on a user friendly interface. Vehicles that are suspected to have a violation are automatically alerted to the enforcement staff. The main goal of the SIRIS field operational test (FOT) was to collect data to evaluate the performance of the prototype system and determine the viability of such a system being used for commercial motor vehicle enforcement. From March 2010 to September 2010, ORNL facilitated the SIRIS FOT at the Greene County Inspection Station (IS) in Greeneville, Tennessee. During the course of the FOT, 413 CMVs were given a North American Standard (NAS) Level-1 inspection. Of those 413 CMVs, 384 were subjected to a SIRIS screening. A total of 36 (9.38%) of the vehicles were flagged by SIRIS as having one or more thermal issues; with brakes issues making up 33 (91.67%) of those. Of the 36 vehicles flagged as having thermal issues, 31 (86.11%) were found to have a violation and 30 (83.33%) of those vehicles were placed out-of-service (OOS). Overall the enforcement personnel who have used SIRIS for screening purposes have had positive feedback on the potential of SIRIS. With improvements in detection algorithms and stability, the system will be beneficial to the CMV enforcement community and increase overall trooper productivity by accurately identifying a higher percentage of CMVs to be placed OOS with minimal error. No future evaluation of SIRIS has been deemed necessary and specifications for a production system will soon be drafted.

  7. Development of an AC Module System: Final Technical Report

    SciTech Connect

    Suparna Kadam; Miles Russell


    The GreenRay Inc. program focused on simplifying solar electricity and making it affordable and accessible to the mainstream population. This was accomplished by integrating a solar module, micro-inverter, mounting and monitoring into a reliable, 'plug and play' AC system for residential rooftops, offering the following advantages: (1) Reduced Cost: Reduction in installation labor with fewer components, faster mounting, faster wiring. (2) Maximized Energy Production: Each AC Module operates at its maximum, reducing overall losses from shading, mismatch, or module downtime. (3) Increased Safety. Electrical and fire safety experts agree that AC Modules have significant benefits, with no energized wiring or live connections during installation, maintenance or emergency conditions. (4) Simplified PV for a Broader Group of Installers. Dramatic simplification of design and installation of a solar power system, enabling faster and more efficient delivery of the product into the market through well-established, mainstream channels. This makes solar more accessible to the public. (5) Broadened the Rooftop Market: AC Modules enable solar for many homes that have shading, split roofs, or obstructions. In addition, due to the smaller building block size of 200W vs. 1000W, homeowners with budget limitations can start small and add to their systems over time. Through this DOE program GreenRay developed the all-in-one AC Module system with an integrated PV Module and microinverter, custom residential mounting and performance monitoring. Development efforts took the product from its initial concept, through prototypes, to a commercial product sold and deployed in the residential market. This pilot deployment has demonstrated the technical effectiveness of the AC Module system in meeting the needs and solving the problems of the residential market. While more expensive than the traditional central inverter systems at the pilot scale, the economics of AC Modules become more and more

  8. Photovoltaic and photoelectrochemical conversion of solar energy.


    Grätzel, Michael


    The Sun provides approximately 100,000 terawatts to the Earth which is about 10000 times more than the present rate of the world's present energy consumption. Photovoltaic cells are being increasingly used to tap into this huge resource and will play a key role in future sustainable energy systems. So far, solid-state junction devices, usually made of silicon, crystalline or amorphous, and profiting from the experience and material availability resulting from the semiconductor industry, have dominated photovoltaic solar energy converters. These systems have by now attained a mature state serving a rapidly growing market, expected to rise to 300 GW by 2030. However, the cost of photovoltaic electricity production is still too high to be competitive with nuclear or fossil energy. Thin film photovoltaic cells made of CuInSe or CdTe are being increasingly employed along with amorphous silicon. The recently discovered cells based on mesoscopic inorganic or organic semiconductors commonly referred to as 'bulk' junctions due to their three-dimensional structure are very attractive alternatives which offer the prospect of very low cost fabrication. The prototype of this family of devices is the dye-sensitized solar cell (DSC), which accomplishes the optical absorption and the charge separation processes by the association of a sensitizer as light-absorbing material with a wide band gap semiconductor of mesoporous or nanocrystalline morphology. Research is booming also in the area of third generation photovoltaic cells where multi-junction devices and a recent breakthrough concerning multiple carrier generation in quantum dot absorbers offer promising perspectives. PMID:17272237

  9. Dynamic simulation of sulfur-removal systems. Final report

    SciTech Connect

    Alexander, J.H.; Blake, T.R.; Brownell, D.H. Jr.; Henline, W.D.; Wilkins, D.E.


    A generalized computer simulation has been developed to predict the dynamic response of alternate gas absorption systems for selective removal of sulfur compounds or ammonia from fuel gas or synthesis gas produced from coal or other fossil fuels. The models use numerical methods based upon finite difference techniques to determine the spatial distribution of process variables within both the absorption and regeneration columns of such gas cleanup processes. The simulator may be applied to systems for selective gas absorption based on either chemical or physical principles. Examples of such systems include the Benfield process based on absorption by chemical reaction with an activated alkali carbonate solvent, and the Allied SELEXOL Solvent Process based on physical absorption as a result of partial pressure differences of the gas components above an organic solvent system. Simulations of either individual process units or an entire integrated plant can be performed. This computer program has specifically been structured to permit convenient flow sheet modification, as well as addition of new units. This research has emphasized the development of a general theoretical structure which can be easily modified by substituting alternate sets of data on the physicochemical properties of the appropriate liquid solvent. This model has been applied to Selexol Solvent Processes using both published and proprietary data on solvent properties. Test calculations have been performed to simulate open loop response of individual scrubber towers, and the complete system, to input composition and flow rate transients.

  10. Assessment of fuel-gas-cleanup systems. Final report

    SciTech Connect

    Robson, F.L.; Blecher, W.A.


    This report presents the results of a study to evaluate the performance, economics and emission characteristics of low-, medium-, and high-temperature fuel gas cleanup processes for use in coal gasification combined-cycle power plants based on high-temperature gas turbines. Processes considered were the Allied Chemical low-temperature Selexol process, METC medium-temperature iron oxide process and Conoco high-temperature half-calcined dolomite process. Process evaluations were carried out for twenty-four combinations of gasifiers and cleanup processes. Based upon the process evaluations, five combinations of gasifiers and cleanup process were selected for integration with an advanced, 2600 F gas turbine into an overall power system. Heat and mass balances and process schematics for these plants were prepared and the cost of electricity estimated. The results of the study indicate that medium- or high-temperature cleanup systems in combined-cycle power plants could meet or exceed EPA New Source Performance Standards. Performance and cost of the systems studied can be improved by high- and intermediate-temperature cleanup systems or by integration of developmental hot gas heat exchangers with suitable commercially available low-temperature cleanup systems. Unresolved problems in the use of medium- and high-temperature cleanup are efficient regeneration of iron oxide, particulate removal at high temperature and the fate of fuel bound nitrogen and trace metals that may appear in the hot fuel gas.