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Back Contact Effects on the Electro-Optical Properties of CdTe/CdS Solar Cells

Description: Studies of junction photoluminescence (PL) in CdTe/CdS solar cells reveal that back-contact application produces a dramatic qualitative change in the junction picosecond-PL spectrum. Prior to contact application, the spectrum has two peaks at energies of 1.501 eV and 1.457 eV, corresponding to recombination in regions of CdTeS alloy with 2% and 12% sulfur content, respectively. After contact application, the spectrum consists of a single broad peak at 1.48 eV. Previous studies have shown that the nitric-phosphoric (NP) etch used in the contact procedure produces a layer of elemental tellurium (Te) on the CdTe surface. We postulate that the change in the near-junction PL spectrum is caused by a grain-boundary field effect due to perturbations of the grain-boundary conductivity and Fermi level.
Date: October 15, 1998
Creator: Levi, D. H.; Albin, D. S.; Gessert, T. A. (National Renewable Energy Laboratory) & Woods, L. M. (Department of Electrical Engineering, Colorado State University, Ft. Collins, CO)
Partner: UNT Libraries Government Documents Department

Advanced Processing of CdTe- and CuInxGa1-xSe2-Based Solar Cells: Final Report: 18 April 1995 - 31 May 1998

Description: This report summarizes work performed by the University of South Florida Department of Electrical Engineering under this subcontract. The Cadmium telluride(CdTe) portion of this project deals with the development of high-efficiency thin-filmed CdTe solar cells using fabrication techniques that are suitable for manufacturing environments.
Date: January 13, 1999
Creator: Morel, D. L.; Ferekides, C. S.; Bhatt, R.; Jayapalan, A.; Komin, V.; Lin, H. et al.
Partner: UNT Libraries Government Documents Department

Electroosmosis effect on micro permeability through rock samples

Description: It is a well known fact that a liquid flowing through a microporous media creates a potential difference between entry and exit of the sample. This phenomenon is known as streaming potential. In an other hand, when a potential difference is applied through an impregnate rock sample, a flow is induced, this is called electroosmosis effect. In this paper, we examine electroosmosis experiments made in a percolation cell in which two gold electrodes are placed in the inner and in the outer chamber. The temperature, the pressure and potential difference, the flow, the current and the chemical composition of water in chambers may be recorded. Experiment consist to the application of electric field through the sample and to observe the evolution of the flow, the electrical current and the chemical dissolution.
Date: January 24, 1996
Creator: G., Touchard; Paillat, T.; Beaufort, D. & Watanabe, S.
Partner: UNT Libraries Government Documents Department

Input Impedance of a Probe Antenna Exciting a TEM Cell

Description: Abstract: The input impedance of a probe antenna exciting a transverse electromagnetic (TEM) transmission line cell is formulated by a variational approach. The formulation also utilizes the results from a previous work on the field distribution inside a TEM cell excited by a vertical electrical Hertzian dipole. The final result of imoedance is shown to consist of two distinct terms, which are respectively contributed by the ordinary rectangular waveguide and the gap perturbation. Numerical results for both the real and imaginary parts of the impedance are given. The resistive part is found to be proportional to the square of the probe length, and the reactive part largely capacitive.
Date: April 1982
Creator: Wilson, Perry F.; Chang, David C. & Ma, Mark T.
Partner: UNT Libraries Government Documents Department

PICASSO: A GENERAL INTERACTIVE GRAPHICS MODELING PROGRAM.

Description: This report is intended to serve as a user's manual for PICASSO. The detailed description of the concepts involved and the methods used in implementing those concepts will be treated in a subsequent paper and are incorporated in the Ph.D. thesis of one of the authors. The program evolved from earlier work on a graphics program for printed circuit board design which had a fixed library of elements. The need for a dynamic graphics program (i.e., one which allows the creation of new elements as required) soon became obvious, and the generality of such a program for mathematical modeling was a major factor in the development of PICASSO. It was thought that the present stage of development of this modeling program had reached a point that a report such as this would be useful in creating a broader interest in the field. However, work continues to further generalize the program into such areas as computer animation, 3-D display and modeling, and a more general interface to available ''analysis'' routines, such as the available compilers and interpreters. It should be emphasized that the program is continually changing as new ideas and applications arise. For example, in order to create a modeling system which is complete in some sense, PICASSO was designed explicitly to interface with the CDC analysis program MIMIC. The next step, already under investigation, is to allow for user-defined output templates to specify,the form of the output of a model. This feature, along with the capability for multiple definitions of an element, will allow for several types of analysis to be done on a single model. Another innovation being studied is the provision for ''robot'' commands, with which the user may define a sequence of. commands to be carried out on demand, in much the same way as mechanical ...
Date: January 1, 1972
Creator: Austin, D.M. & Holmes, H.H.
Partner: UNT Libraries Government Documents Department

Applications of wireless sensors in monitoring Indoor Air Quality in the classroom environment [Poster]

Description: This poster discusses applications of wireless sensors in monitoring indoor air quality in the classroom environment. The focus of this research project was to investigate Indoor Air Quality monitoring technologies, government regulations and policies, and best practices to improve IAQ.
Date: 2012
Creator: Chamberlain, Blaine; Jordan, Georgette; Li, Xinrong; Thompson, Ruthanne; Borkar, Chirag & Mansour, Sahar
Partner: UNT College of Engineering

Stability and heat transfer in time-modulated flows

Description: In May 1991, DOE awarded grant DE-FG02-91ER14179 for the investigation of stability and heat transfer in time-modulated flows. The general objectives of the research being: (1) to demonstrate and quantify theoretically and experimentally the physics of modulational instability; (2) to exhibit experimentally and describe theoretically the sensitivity of modulational instability to harmonic content of the basic state; (3) to model the influence of mean-flow on modulational instability: (4) to examine practical design implications of the results with particular attention given to heat transfer. During the last six months, the emphasis of the research has been placed on objective 1 as it relates to the fundamental physical mechanisms, experiment design, and techniques required for the demonstration and description of the modulational instability.
Date: January 1, 1991
Creator: Thompson, C.
Partner: UNT Libraries Government Documents Department

Executive Correspondence – Letter received 08/08/05 by the BRAC Commission from Princeton University Professor of Electrical Engineering Daniel C. Tsui

Description: Executive Correspondence – Letter received 08/08/05 by the BRAC Commission from Princeton University Professor of Electrical Engineering Daniel C. Tsui criticizing DoD’s recommendation to move the Army Research Office (ARO) from North Carolina to Bethesda, MD and explaining how such a move would severely compromise ARO’s ability to provide revolutionary advances to the Army.
Date: August 11, 2005
Partner: UNT Libraries Government Documents Department

Single Molecule Junctions: Probing Contact Chemistry and Fundamental Circuit Laws

Description: By exploiting selective link chemistry, formation of single molecule junctions with reproducible conductance has become established. Systematic studies reveal the structure-conductance relationships for diverse molecules. I will draw on experiments from my collaborators at Columbia University, atomic-scale calculations and theory to describe progress in two areas. First, I will describe a novel route to form single molecule junctions, based on SnMe3 terminated molecules, in which gold directly bonds to carbon in the molecule backbone resulting in near ideal contact resistance [1]. Second, comparison of the conductance of junctions formed with molecular species containing either one backbone or two backbones in parallel allows demonstration of the role of quantum interference in the conductance superposition law at the molecular scale [2].
Date: April 11, 2013
Creator: S., Hybertsen M.
Partner: UNT Libraries Government Documents Department

Demand Controlled Ventilation using CO2 Sensors in a Wireless Sensor Network [Poster]

Description: Poster presented as part of the 2013 Research Experiences for Teachers (RET) in Sensor Education, a National Science Foundation (NSF) funded grant project. This poster discusses research on demand controlled ventilation using CO₂ sensors in a wireless sensor network.
Date: 2013
Creator: Parsons, David; Jordan, Georgette; Li, Xinrong; Thompson, Ruthanne & Abraham, Sherin
Partner: UNT College of Engineering

Bringing real world applications for wireless sensor networks into the classroom: Telemetric monitoring of water quality in an artificial stream [2012: Poster]

Description: This poster discusses research on bringing real world applications for wireless sensor networks into the classroom and covers the use of a wireless sensor network (WSN) using the ZigBee protocol to remotely monitor an artificial aquatic ecosystem.
Date: 2012
Creator: Bunn, Zac; Guerrero, Jose; Wolf, Lori; Fu, Shengli; Hoeinghaus, David; Driver, Luke et al.
Partner: UNT College of Engineering

Low cost, compact, and high efficiency traction motor for electric and hybrid electric vehicles

Description: A new motor drive, the switched reluctance motor drive, has been developed for hybrid-electric vehicles. The motor drive has been designed, built and tested in the test bed at a near vehicle scale. It has been shown that the switched reluctance motor drive is more suitable for traction application than any other motor drive.
Date: October 7, 2002
Creator: Ehsani, Mark
Partner: UNT Libraries Government Documents Department

The Use of Thyristors for Repetitive Narrow Pulse, High Power Switching

Description: Inverter type thyristors were switched repetitively to failure with 1 {micro}s pulses at repetition rates of 10, 50 and 100 pps and at peak currents up to 12 kA. Millions of pulses could be obtained before failure if the peak current were held at around 6 kA.
Date: January 13, 2000
Creator: BAYNE,S.B.; PORTNOY,W.M. & ROHWEIN,G.J.
Partner: UNT Libraries Government Documents Department

Planar channeling radiation from relativistic positrons and electrons in LiF

Description: Channeling radiation has been measured for planar-channeled 54- and 83-MeV positrons and 17-, 31-, and 54-MeV electrons in the ionic crystal LiF. The results are shown to be in reasonable, but not perfect, agreement with the results of many-beam calculations based upon a model of the crystal as an array of isolated Li/sup +/ and F/sup -/ ions.
Date: July 1, 1983
Creator: Berman, B.L.; Datz, S.; Fearick, R.W.; Swent, R.L.; Pantell, R.H.; Park, H. et al.
Partner: UNT Libraries Government Documents Department

Miniature Nuclear Magnetic Resonance Spectrometer For In-Situ And In-Process Analysis And Monitoring

Description: The main purpose of this research is to develop a nuclear magnetic resonance (NMR) spectrometer that is small enough to be held in the palm of a hand. Such an instrument could be used in many applications of importance to DOE as well as to industry. These applications would include in-field characterization of contaminants, monitoring and analysis of chemical processes in chemical plants and other environmental monitoring applications. In addition to having drastically reduced size and cost, a miniature NMR instrument would be ideally suited for chemical analysis of volume limited samples which frequently occur in biological, medical and drug development applications.
Date: June 1, 1999
Creator: Friemand, Gennady & Feinerman, Alan
Partner: UNT Libraries Government Documents Department

Application and Network-Cognizant Proxies - Final Report

Description: OAK B264 Application and Network-Cognizant Proxies - Final Report. Current networks show increasing heterogeneity both in terms of their bandwidths/delays and the applications they are required to support. This is a trend that is likely to intensify in the future, as real-time services, such as video, become more widely available and networking access over wireless links becomes more widespread. For this reason they propose that application-specific proxies, intermediate network nodes that broker the interactions between server and client, will become an increasingly important network element. These proxies will allow adaptation to changes in network characteristics without requiring a direct intervention of either server or client. Moreover, it will be possible to locate these proxies strategically at those points where a mismatch occurs between subdomains (for example, a proxy could be placed so as to act as a bridge between a reliable network domain and an unreliable one). This design philosophy favors scalability in the sense that the basic network infrastructure can remain unchanged while new functionality can be added to proxies, as required by the applications. While proxies can perform numerous generic functions, such as caching or security, they concentrate here on media-specific, and in particular video-specific, tasks. The goal of this project was to demonstrate that application- and network-specific knowledge at a proxy can improve overall performance especially under changing network conditions. They summarize below the work performed to address these issues. Particular effort was spent in studying caching techniques and on video classification to enable DiffServ delivery. other work included analysis of traffic characteristics, optimized media scheduling, coding techniques based on multiple description coding, and use of proxies to reduce computation costs. This work covered much of what was originally proposed but with a necessarily reduced scope.
Date: March 24, 2003
Creator: Ortega, Antonio & Lee, Daniel C.
Partner: UNT Libraries Government Documents Department

Crystalline growth of wurtzite GaN on (111) GaAs

Description: Gallium Nitride films were grown on (111) gallium arsenide substrates using reactive rf magnetron sputtering. Despite a 20% lattice mismatch and different crystal structure, wurtzite. Heteroepitaxy was observed for growth temperatures between 550-600{degrees}C. X-ray diffraction patterns revealed (0002) GaN peak with a full-width-half-maximum (FWHM) as narrow as 0.17{degree}. Possible surface reconstructions to explain the epitaxial growth are presented.
Date: December 1, 1991
Creator: Ross, J.; Gustafson, T.K. (California Univ., Berkeley, CA (United States). Dept. of Electrical Engineering and Computer Sciences) & Rubin, M. (Lawrence Berkeley Lab., CA (United States))
Partner: UNT Libraries Government Documents Department

Effective activation energy in the Bi-Sr-Ca-Cu-O systems

Description: Magnetic relaxation in the Bi-Sr-Ca-Cu-O systems has been investigated in a wide temperature regime. Previously reported studies of the effective activation energy, U, have been controversial in terms of temperature and field dependence of the critical current density, j[sub c]. We have considered the temperature dependence of j[sub c] and constructed the U-j (or M) curves for the Bi-Sr-Ca-Cu-O system. We found that at a constant driving force and temperature, U is considerably higher for 2245 samples than for 2223 samples. This enhancement can be attributed to the flux pinning from finely dispersed calcium- and copper- rich precipitates.
Date: August 1, 1992
Creator: Sengupta, S.; Shi, D.; Wang, Z.; Smith, M. (Argonne National Lab., IL (United States)) & McGinn, P.J. (Notre Dame Univ., IN (United States). Dept. of Electrical Engineering)
Partner: UNT Libraries Government Documents Department

Final report on work for Center for Gyrokinetic Particle Simulation of Turbulent Transport in Burning Plasmas — Tools for Improved Data Logistics

Description: This project focused on the use of Logistical Networking technology to address the challenges involved in rapid sharing of data from the the Center's gyrokinetic particle simulations, which can be on the order of terabytes per time step, among researchers at a number of geographically distributed locations. There is a great need to manage data on this scale in a flexible manner, with simulation code, file system, database and visualization functions requiring access. The project used distributed data management infrastructure based on Logistical Networking technology to address these issues in a way that maximized interoperability and achieved the levels of performance the required by the Center's application community. The work focused on the development and deployment of software tools and infrastructure for the storage and distribution of terascale datasets generated by simulations running at the National Center for Computational Science at Oak Ridge National Laboratory.
Date: September 14, 2008
Creator: Beck, Micah
Partner: UNT Libraries Government Documents Department

Defect Structures in Semiconducting ReSi{sub 2-x} Epitaxial Thin Films

Description: Narrow band gap semiconductors such as ReSi{sub 2{minus}x} (Eg {approximately} 0.12 eV) are potential materials for infrared detectors. Further, ReSi{sub 2{minus}x} is in thermodynamic equilibrium and has a very small lattice mismatch with Si offering the potential of developing ReSi{sub 2{minus}x} heterojunction devices where the detector element and the signal processing circuitry can be integrated on one Si chip. In a previous study, strong crystallographic alignment between ReSi{sub 2{minus}x} film and (001)Si substrate was observed by ion channeling. In this study, a transmission electron microscopy (TEM) study has been performed on ReSi{sub 2{minus}x} epitaxial films on (001) Si. Comparisons are made to our previous microscopy study on the defect structures in bulk single crystals of ReSi{sub 2{minus}x}.
Date: February 1, 1999
Creator: Mahan, J.E.; Mirsa, A. & Mitchell, T.E.
Partner: UNT Libraries Government Documents Department