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Low-Cost Photovoltaic Cell Mount Study

Description: From abstract: This report is a technical and economic evaluation of five representative cell laydown techniques with the final goal being a determination of which was most promising from a cost performance basis.
Date: March 1980
Creator: Motorola, inc. Government Electronics Division.
Partner: UNT Libraries Government Documents Department

RECORDING EQUIPMENT FOR INTERNAL FRICTION MEASUREMENTS

Description: An apparatus was developed for recording internal friction data in such a manner as to circumvent many of the laborious and time-consuming observations and calculations usually associated with these measurements. An optical lever is used and the passage of the beam across the scale is detected by photoconductive cells. The cells are strategically located so that, when their signals are fed through a multichannel switching circuit to the pens of an operation recorder, a plot of the logarithm of the vibrational amplitude versus the number of cycles is recorded on the chart. From the definitmon of the logarithmic decrement, ( delta ), it can be shown that the slope of this curve is - delta . The apparatus is inexpensive and requires a minimum of maintenance. It has been used for accurate determinations of values of delta from below 0.0001 up to 0.3. (auth)
Date: October 31, 1961
Creator: Stephenson, R.L. & McCoy, H.E. Jr.
Partner: UNT Libraries Government Documents Department

The Status of Thermophotovoltaic Energy Conversion Technology at Lockheed Martin Corporation

Description: In a thermophotovoltaic (TPV) energy conversion system, a heated surface radiates in the mid-infrared range onto photocells which are sensitive at these energies. Part of the absorbed energy is converted into electric output. Conversion efficiency is maximized by reducing the absorption of non-convertible energy with some form of spectral control. In a TPV system, many technology options exist. Our development efforts have concentrated on flat-plate geometries with greybody radiators, front surface tandem filters and a multi-chip module (MCM) approach that allows selective fabrication processes to match cell performance. Recently, we discontinued development of GaInAsSb quaternary cell semiconductor material in favor of ternary GaInAs material. In our last publication (Ref. 1), the authors reported conversion efficiencies of about 20% (radiator 950 C, cells 22 C) for small modules (1-4 cm{sup 2}) tested in a prototypic cavity test environment. Recently, we have achieved measured conversion efficiencies of about 12.5% in larger ({approx}100 cm{sup 2}) test arrays. The efficiency reduction in the larger arrays was probably due to quality and variation of the cells as well as non-uniform illumination from the hot radiator to the cold plate. Modules in these tests used GaInAsSb cells with 0.52 eV bandgap and front surface filters for spectral control. This paper provides details of the individual system components and the rationale for our technical decisions. It also describes the measurement techniques used to record these efficiencies.
Date: July 29, 2004
Creator: Brown, EJ; Baldasaro, PF; Burger, SR; Danielson, LR; DePoy, DM; Dolatowski, JM et al.
Partner: UNT Libraries Government Documents Department

Improving the performance of photo-electrically controlled lighting systems

Description: The ability of a photo-electrically controlled lighting system to maintain a constant total light level on a task surface by responding to changing daylight levels is affected by the control algorithm used to relate the photosensor signal to the supplied electric light level and by the placement and geometry of the photosensor. We describe the major components of a typical control system, discuss the operation of three different control algorithms, and derive expressions for each algorithm that express the total illuminance at the task as a function of the control photosensor signal. Using a specially-designed scale model, we measured the relationship between the signal generated by various ceiling-mounted control photosensors and workplane illuminance for two room geometries under real sky conditions. The measured data were used to determine the performance of systems obeying the three control algorithms under varying daylight conditions. Control systems employing the commonly-used integral reset algorithm supplied less electric light than required, failing to satisfy the control objective regardless of the control photosensor used. Systems employing an alternative, closed-loop proportional control algorithm achieved the control objective under virtually all tested conditions when operated by a ceiling-mounted photosensor shielded from direct window light.
Date: August 1, 1988
Creator: Rubinstein, F.; Ward, G. & Verderber, R.
Partner: UNT Libraries Government Documents Department

Mercuric Iodide Photocell Technology for Room Temperature Readout of Scintillators

Description: Mercuric iodide (HgI2) is a well known material for the direct detection of gamma rays; however, the largest volume achievable is limited by thickness of the detector, which needs to be a small fraction of the average trapping length for electrons. We are reporting here preliminary results in using HgI2 crystals to fabricate photocells used in the readout of various scintillators. The optical spectral response and efficiency of these photocells were measured and will be reported. Preliminary nuclear response from a HgI2 photocell that was optically matched to a Ce3+ :LaBr3 scintillator will also be presented and discussed. Further improvements will be sought by optimizing the transparent contact technology.
Date: August 31, 2007
Creator: al., Warnick Kernan et
Partner: UNT Libraries Government Documents Department

AUTOMATIC DOSE COMPUTER FOR RADIATION FILM BADGES

Description: A combination densitomer and analog computer is described which determines radiation exposure of photographic film used in personnel badges. The range of the instrument is 0to 300 mr gamma and 0 to 300 mrad BETA plus gamma . A novel phototube circuit is used to obtain logarithms directly. (auth)
Date: April 1, 1960
Creator: Davis, J.E.
Partner: UNT Libraries Government Documents Department

Development of High Resolution Scintillator Systems Based on Photocell Technology

Description: Inorganic scintillator/photomultiplier-based spectrometers are the systems of choice for a multitude of X-ray and gamma radiation measurement applications. Despite widespread use, they have numerous shortcomings. The most serious shortcoming is the relatively poor energy resolution that makes isotope identification problematic, particularly in the case of trace quantities. Energy resolution in scintillator/photomultiplier tube (PMT) spectrometers is governed by a combination of the crystal intrinsic resolution that includes non-linearity effects, photomultiplier statistics, and the variability in the probability of a scintillation photon generating a photoelectron at the photocathode. It is evident that energy resolution in these systems is linked to both the physics of light generation in the scintillator and the characteristics of the PMT. PMTs also present design problems, especially in the case of handheld and portable instruments, due to their considerable weight and volume. Additionally, PMTs require well-regulated high voltage, and are vulnerable to magnetic fields. The objective of this work is to provide instrument designers of scintillation-based gamma-ray spectrometers with superior energy resolution and greatly reduced weight and volume. It is planned to achieve this advancement by optimizing the performance of a new class of inorganic scintillators by matching their emission spectra with the enhanced quantum efficiency of certain photocells.
Date: January 1, 2006
Creator: Kernan, W. J.; Franks, L. A.; Groza, M. & Burger, A.
Partner: UNT Libraries Government Documents Department

Reduction of photovoltaic cell reverse breakdown by a peripheral bypass diode

Description: A photovoltaic cell in a series-connected string can be forced to operate in a power-dissipation mode when the cell's short-circuit current is reduced below the string current as a result of cracking or shadowing. New techniques for significantly reducing the power dissipated are reported based on locating protection for the cell around its periphery. One approach uses a standard diode, thereby requiring processing; the other approach uses a backward diode, which requires one additional doping step. Theoretical considerations and experimental results are presented. Initial devices yield a power-dissipation reduction of more than a factor of 10 with the backward diode and over 30 for the standard diode. It is found that the standard diode requires a slight increase in cell-interconnect complexity while the backward diodes uses conventional interconnections.
Date: January 1, 1982
Creator: Cox, III, C H; Silversmith, D J & Mountain, R W
Partner: UNT Libraries Government Documents Department

Module Utilization Committee. Final report

Description: Photovoltaic collector modules were declared surplus to the needs of the US Department of Energy. The Module Utilization Committee was formed to make appropriate disposition of the surplus modules. The final report of that committee accounts for that disposition. The membership and activities of the committee are set forth and the results of its activities are reported.
Date: March 1, 1984
Partner: UNT Libraries Government Documents Department

Improving the performance of photo-electrically controlled lighting systems

Description: The ability of a photo-electrically controlled lighting system to maintain a constant total light level on a task surface by responding to changing daylight levels is affected by the control algorithm used to relate the photosensor signal to the supplied electric light level and by the placement and geometry of the photosensor. We describe the major components of a typical control system, discuss the operation of three different control algorithms, and derive expressions for each algorithm that express the total illuminance at the task as a function of the control photosensor signal. Using a specially-designed scale model, we measured the relationship between the signal generated by various ceiling-mounted control photosensors and workplane illuminance for two room geometries under real sky conditions. The measured data were used to determine the performance of systems obeying the three control algorithms under varying daylight conditions. Control systems employing the commonly-used integral reset algorithm supplied less electric light than required, failing to satisfy the control objective regardless of the control photosensor used. Systems employing an alternative, closed-loop proportional control algorithm achieved the control objective under virtually all tested conditions when operated by a ceiling-mounted photosensor shielded from direct window light.
Date: August 1, 1988
Creator: Rubinstein, F.; Ward, G. & Verderber, R.
Partner: UNT Libraries Government Documents Department

Automatic lighting controls demonstration: Long-term results. Final report, July 1991

Description: An advanced electronically ballasted lighting control system was installed in a portion of an office building to measure the energy and demand savings. The lighting control system used an integrated lighting control scenario that included daylight following, lumen depreciation correction, and scheduling. The system reduced lighting energy on weekdays by 62% and 51% in the north and south daylit zones, respectively, compared to a reference zone that did not have controls. During the summer, over 75% energy savings were achieved on weekdays in the north daylit zone. Even in the south interior zone, which benefitted lime from daylight, correction strategies and adjustment of the aisleway lights to a low level resulted in energy use of only half that of the reference zone. Although, in general, the savings varied over the year due to changing daylight conditions, the energy reduction achieved with controls could be fit using a simple analytical model. Significant savings also occurred during core operating hours when it is more expensive to supply and use energy. Compared to the usage in the reference zone, energy reductions of 49%, 44%, and 62% were measured in the south daylight, south interior, and north daylight zones, respectively, during core operating hours throughout the year. Lighting energy usage on weekends decreased dramatically in the zones with controls, with the usage in the north daylit zone only 10% that of the reference zone. A simple survey developed to assess occupant response to the lighting control system showed that the occupants were satisfied with the light levels provided.
Date: October 18, 1991
Creator: Rubinstein, F.
Partner: UNT Libraries Government Documents Department

LDRD final report : energy conversion using chromophore-functionalized carbon nanotubes.

Description: With the goal of studying the conversion of optical energy to electrical energy at the nanoscale, we developed and tested devices based on single-walled carbon nanotubes functionalized with azobenzene chromophores, where the chromophores serve as photoabsorbers and the nanotube as the electronic read-out. By synthesizing chromophores with specific absorption windows in the visible spectrum and anchoring them to the nanotube surface, we demonstrated the controlled detection of visible light of low intensity in narrow ranges of wavelengths. Our measurements suggested that upon photoabsorption, the chromophores isomerize to give a large change in dipole moment, changing the electrostatic environment of the nanotube. All-electron ab initio calculations were used to study the chromophore-nanotube hybrids, and show that the chromophores bind strongly to the nanotubes without disturbing the electronic structure of either species. Calculated values of the dipole moments supported the notion of dipole changes as the optical detection mechanism.
Date: September 1, 2010
Creator: Vance, Andrew L.; Zifer, Thomas; Zhou, Xinjian; Leonard, Francois Leonard; Wong, Bryan Matthew; Kane, Alexander et al.
Partner: UNT Libraries Government Documents Department

THE SCATTERING OF THERMAL RADIATION INTO OPEN UNDERGROUND SHELTERS

Description: Animals placed in open underground shelters at the Nevada Test Site during an atomic weapon test suffered skin burns of an unknown origin. From a study of the burns it was concluded that the causative agent entered the shelter from outside. the causative agent was subject to rectilinear propagation near the entrance. and the causative agent required a relatively unobstructed opening to effect entrance. The two most likely agents for such burns are hot winds and/or hot wind-borne dust that are forced into the shelter as the shock front from the weapon passes the shelter entrances and radiant energy from the fireball that is scattered into the shelter. A study was made to evaluate the contribution made by radiant energy and, if this contributioo proved to be significant, to suggest means of eliminating it. Extensive measurements were made in the laboratory on a scale model of the shelter and direct measurements were made on an actual shelter to ensure the validity of the laboraiory results. A Photronic cell and a MacBeth Illuminometer were used to measure the entryway transmission of total radiant energy. The consistency of the results with extended and point sources for the model shelter and the agreement of these results with those from a point source and sunlight for the underground shelter at the Nevada Test Site lead to considerable confidence in the ability to predict the amount of radiant energy that would reach the animals from a weapon of known size. The energy calculated on the basis of these static measurements is about 1/200 of that required to produce the burns. Although transient effects caused by the rapid heating of the entryway walls could have resulted in a considerable increase in the entyway transmission. It is felt thai radiant important causative agent in producing burns within ...
Date: May 1, 1959
Creator: Davis, T.P.; Miller, N.D.; Ely, T.S.; Basso, J.A. & Pearse, H.E.
Partner: UNT Libraries Government Documents Department

Interim implementation structure for development of performance criteria and test standards for photovoltaic systems

Description: This document presents an implementation structure for the near-term development of performance criteria and test methods for photovoltaic (PV) materials, components, subsystems, and systems. The approach is designed to be responsive to the Photovoltaic Research, Development and Demonstration Act of 1978 (PL-95-590). The project is organized into four tasks: (1) establishment of performance criteria and the development of test methods; (2) development of laboratory accreditation/product certification guidelines; (3) development of validation methodologies; and (4) coordination of the quality assurance effort with consensus standards and code organizations. A schedule and milestones are presented for each task. The appendices provide a brief overview of standards and the standards development process. The philosophy behind this project is to develop industry- and user-established performance criteria, test methods, and accreditation procedures which may then be referred to independent consensus standards organizations for the preparation of consensus standards. The emphasis in execution of this approach will be to develop uniform, fair performance criteria and tests and to avoid rigid, prescriptive criteria. Photovoltaics is an emerging technology; criteria written now must be able to accommodate devices and techniques not yet developed.
Date: November 15, 1979
Partner: UNT Libraries Government Documents Department

Solar Energy Education. Social studies: activities and teacher's guide. Field test edition

Description: Solar energy information is made available to students through classroom instruction by way of the Solar Energy Education teaching manuals. In this manual solar energy, as well as other energy sources like wind power, is introduced by performing school activities in the area of social studies. A glossary of energy related terms is included. (BCS)
Date: January 1, 1982
Partner: UNT Libraries Government Documents Department

Development and fabrication of advanced cover glass for a GaAs solar cell

Description: This report summarizes work on improving solar cell conversion efficiencies by modifying the cell cover glass. Two approaches were investigated during the course of this work: grooved cover glasses to reduce the effect of top contact obscuration and secondary concentrators to improve concentrator solar cell performances in tracking modules. The grooved cover glass work used an array of metallized V shaped grooves in a thin cover glass (plastic) window to deflect incident light rays away from solar cell front surface regions covered by the solar cell electrical contact metallization onto unobstructed, optically active regions of the solar cell. Secondary concentrators are being considered for use on concentrator solar cells to improve overall system conversion efficiency and reduce receiver module cost. Secondary concentrators designed and fabricated during this project consist of small glass cones to attach directly to the top of the receiver solar cell. When appropriately designed, these secondary concentrator glass cones increase sunlight concentration on the solar cell, improve solar flux uniformity on the cell, improve system tolerance to tracking error, and allow for concentration ratios greater than can be ordinarily achieved with acrylic Fresnel lenses.
Date: January 1, 1984
Creator: Borden, P.G.; Kaminar, N.R. & Grounner, M.
Partner: UNT Libraries Government Documents Department

Design, analysis, and test verification of advanced encapsulation system. Triannual report for period ending March 31, 1980

Description: Two strawman designs have been devised to aid in the development of analytical techniques for evaluating advanced solar cell encapsulation systems designs. The optical model for a multi-layer system in which reflection, absorption, and transmission may occur between layers, was completed and analytically verified. An expression giving the electrical safety criteria for a multi-layer dielectric system has been derived. A thermal analytical analysis program has been developed which will accommodate up to six different material layers for the determination of NOCT. MSC/NASTRAN has been selected as the primary structural analysis computer code. A matrix of materials and properties has been prepared. Work has begun in finding the necessary material properties.
Date: April 1, 1980
Creator: Allison, K.; Garcia, A. & Minning, C.
Partner: UNT Libraries Government Documents Department

Automated Array Assembly, phase 2. Quarterly technical progress report, January-March 1979

Description: This contract provides for the fabrication of modules from large area tandem junction cells (TJC). The key activities in this contract effort are a) Large Area TJC including cell design, process verification and cell fabrication and b) Tandem Junction Module (TJM) including definition of the cell-module interfaces, substrate fabrication, interconnect fabrication and module assembly. The overall goal is to advance solar cell module process technology to meet the 1986 goal of a production capability of 500 megawatts per year at a cost of less than $500 per peak kilowatt. This contract will focus on the Tandem Junction Module process. During this quarter, effort was focused on the design of a large area, approx. 36 cm/sup 2/, TJC and process verification runs. The large area TJC design was optimized for minimum I/sup 2/R power losses. In the TJM activity, the cell-module interfaces were defined, module substrates were formed and heat treated and clad metal interconnect strips were fabricated. All activities are on or ahead of schedule.
Date: April 1, 1979
Creator: Carbajal, B.G.
Partner: UNT Libraries Government Documents Department

500-watt commercialized concentrator system

Description: A passively cooled, single-axis tracking, polar-axis mounted photovoltaic concentrator system has been designed, fabricated, installed, and tested. System description, design considerations, system performance and a production cost estimate are detailed.
Date: February 1, 1983
Creator: Ronney, K. & Aerni, E.
Partner: UNT Libraries Government Documents Department