ERIC Educational Resources Information Center
King, Richard C.
1981-01-01
Describes the use of solar cookers in the science classroom. Includes instructions for construction of a solar cooker, an explanation of how solar cookers work, and a number of suggested activities. (DS)
Magney, G.K.
1992-12-31
The author describes the activities of SERVE, a Christian relief and development agency, to introduce solar ovens to the Afghan refugees in Pakistan. It has provided 5,000 solar cookers since 1984. The experience has demonstrated the potential of the technology and the need for a durable and reliable product. Common complaints about the cookers are discussed and the ideal cooker is described.
Solar Cooker Lab--Instructor's Guide Motivation
Anderson, Betty Lise
Solar Cooker Lab--Instructor's Guide Motivation: The purpose behind this solar a tool that could greatly increase someone's quality of life. Solar cookers and questions instead of step by step instructions of how to build a solar cooker
TESTING AND REPORTING SOLAR COOKER PERFORMANCE
Technology Transfer Automated Retrieval System (TEKTRAN)
This Standard for quantifying solar cooker performance specifies that test results be presented as cooking power, in Watts, normalized for ambient conditions, relative to the temperature difference betweeen cooker contents and ambient air, both as a plot and as a regression equation for no less than...
Advanced solar box and flat plate collector cookers
Grupp, M.; Bergler, H.
1992-12-31
Several new solar cooker systems have been developed at Synopsis during the last years: advanced box type cookers, featuring an optimized heat transfer from the absorber into the cooking vessel; flat plate cookers, based on a particular two-way collector with air as transfer fluid; flat plate cookers with heat-pipe transfer; specialized cookers for the baking of bread and flat bread. The working principle of these cookers is described, the structure of a thermal simulation model and results of thermal tests are presented. The results of the first year of local production and use of advanced boxes in India are reported.
Promotion of solar box cooker technology
Stibravy, R.
1992-09-01
Over 1.5 billion people are affected by fuel wood shortage, according to the UN Food and Agricultural Organization. Meanwhile solar cookers are under-exploited. The author presents one version of this technology and discusses how it may be promoted world-wide. The increased use of non fossil fuel energy is essential world-wide in combating global warming trends, preserving the environment, conserving resources and achieving sustainable development. The Solar Box Cooker (SBC) - a box within a box - uses an easily available source of such energy that is also renewable (in contrast to energy that, once used, is not, such as oil, coal, gas, wood). It is also readily available for the developing world, and for much of the developed world too.
Solar thermal collector system modeling and testing for novel solar cooker
Foley, Brian, S.B. (Brian M.). Massachusetts Institute of Technology
2014-01-01
Solar cookers are aimed at reducing pollution and desertification in the developing world. However, they are often disregarded as they do not give users the ability to cook after daylight hours. The Wilson solar cooker is ...
Nutritive value of foods cooked in solar cooker
Devadas, R.P.; Venmathi, A.
1992-12-31
This paper outlines the effects of solar cooking on the nutritive value of foods. Nutrients were measured in foods prepared in solar cookers and compared with those in foods prepared in pressure cookers. The foods prepared were parboiled rice, red gram dhal and beans, all foods commonly used in India. The prepared foods were analyzed for protein, minerals and vitamins and the results are presented in tables. It was concluded that solar cookers can be used satisfactorily for preparing cereals and legumes but do not perform well for seasoning, frying and making cheppatti.
Development of an asynchronous solar-powered cooker
Akinwale, P. Femi (Pamela Femi)
2006-01-01
One reason that solar cookers have not gained widespread acceptance is because their use has proved inconvenient and impractical. Users are restricted to cooking when, and where, the sun is shining. Furthermore, the cooking ...
Transient-heat-transfer and stress analysis of a thermal-storage solar cooker module
Zengeni, Hazel C
2014-01-01
This paper details the analysis carried out in Solidworks to determine the best material and configuration of a thermal-storage solar cooker module.The thermal-storage solar cooker utilizes the high-latent-heat lithium ...
SOLAR COOKER UTILIZING SATELLITE DISH TECHNOLOGY A. Saleh1 A. Badran2 1 Mechanical Engineering dishtype solar cooker was built and tested utilizing satellite dish technology. A common satellite-TV dish was utilized as a solar cooker after covering it with a highlyreflective aluminum foil, which
Cookin' with Sun: Design and Build Solar Cookers
ERIC Educational Resources Information Center
Brand, Lance; Warren, Ande; Fitzgerald, Mike
2006-01-01
Having students design and construct solar cookers is a great way to teach them about designing to meet human needs and about many basic global issues related to health and the environment. Because the activity includes solid content from the fields of math, science and technology, it is an excellent vehicle for technology educators who want to…
Solar cooking in Switzerland--Use of cookers in Africa and India
Pulfer, J.
1992-12-31
This paper describes the development of activities in Switzerland, Africa and India to promote the use of solar cookers. The most successful programs are said to be in Senegal in Western Africa, and Kenya and Sudan in Eastern Africa. These activities include information dissemination and sales of ready-made products. Although some projects are for individual homes, some have been developed for hospitals, prisons, schools, boarding houses, etc. These larger units are usually systems using parabolic reflectors and fireplaces or propane as a source of fuel when there is no sunshine.
Solar cooker -- A viable technology for cooking family meals: An empirical study over two years
George, R.
1995-10-01
A solar cooker is a promising renewable energy technology for domestic cooking. A detailed study to assess cooking performance of boxtype solar cooker was carried out during different seasons, viz., pre-winter, winter and summer, over a two year period. The standard menu identified through sample survey of 100 urban families was solar-cooked and cooked in saucepots on coal and kerosene stoves. The ideal period to start solar cooking morning meal fell between 10:00 to 10:30 hours to serve the same around 12:30 hours while loading cooker between 12:00 to 13:30 hours resulted in ready-to-serve evening meal by 14:30 to 15:30 hours. Solar cooking retained nutrients to a greater extent than conventional cooking. The payback period of the cost of a solar cooker at the current price ranged between 260 to 400 active solar cooking days depending on the fuel solar cooker replaced. The paper discusses at length various aspects related to performance of boxtype solar cooker, economics of switching over to solar cooking and policy issues to enhance popularity of solar cooker as an attractive option to combat domestic cooking fuel crisis.
The ``Sol Kitchen'' solar coffee can cooker kit and curriculum package
Donald, R.M.
1999-07-01
The Sol Kitchen Solar Coffee Can Cooker Kit is being developed, by Solar utilities, as a product, with several contexts in mind, including (1) the need to sustain the long term market development of solar energy through education, (2) the need for an improved set of performance criteria for the technology, as it is presented in the classroom and (3) an awareness of newly evolving bench marks in environmental education ({hor_ellipsis}which is about learning how to save the earth.). The category of technology discussed in this paper is the solar cooker, also known as, the solar oven, furnace, or box cooker, with or without reflective panels. The use of full scale solar cookers, modified to act as curriculum aids, can augment educational programs; but only if they work well, are appropriate to the educational objectives, and engage the attention and active involvement of the learners.
Shenandoah parabolic dish solar collector
Kinoshita, G.S.
1985-01-01
The objectives of the Shenandoah, Georgia, Solar Total Energy System are to design, construct, test, and operate a solar energy system to obtain experience with large-scale hardware systems for future applications. This report describes the initial design and testing activities conducted to select and develop a collector that would serve the need of such a solar total energy system. The parabolic dish was selected as the collector most likely to maximize energy collection as required by this specific site. The fabrication, testing, and installation of the parabolic dish collector incorporating improvements identified during the development testing phase are described.
Plane and parabolic solar panels
J. H. O. Sales; A. T. Suzuki
2009-05-14
We present a plane and parabolic collector that absorbs radiant energy and transforms it in heat. Therefore we have a panel to heat water. We study how to increment this capture of solar beams onto the panel in order to increase its efficiency in heating water.
Plane and parabolic solar panels
Sales, J H O
2009-01-01
We present a plane and parabolic collector that absorbs radiant energy and transforms it in heat. Therefore we have a panel to heat water. We study how to increment this capture of solar beams onto the panel in order to increase its efficiency in heating water.
Twelve years experience with solar cookers: Necessary tools for a clean environment
Nandwani, S.S.
1992-12-31
In this review the author shares his personal experience of 12 years on cooking and working with hot box type Solar Ovens (SO), Electric cum Solar Oven (ECSO) and simple Heat Storage Oven (HESO). In addition to informing, advantages and limitations of conventional hot box Solar Oven, economic, social, ecological, and dissemination aspects will be mentioned. Finally some other applications of the solar cooker alone, as well as combined with other solar thermal devices like water heaters, driers and stills, are discussed.
First and Second Law Efficiencies in the Cooking Process of Eggplant using a Solar Cooker Box-Type
NASA Astrophysics Data System (ADS)
Terres, H.; Chávez, S.; Lizardi, A.; López, R.; Vaca, M.; Flores, J.; Salazar, A.
2015-01-01
In this work an experimental procedure and the determination of first and second law efficiencies for the cooking process of eggplant using a solar cooker box-type are shown. The eggplant was modelled as cylinder. In the experimental process a NI Compact Field Point was used as acquisition data system which allows measure temperatures in simultaneous form. The temperatures evolution was defined using thermocouples located at water, surface and central point of the eggplant. After to measure the evolution temperatures in a solar cooker thermodynamics principles were applied to determine the first and second laws. The results obtained indicates what is the numerical difference between the first and second laws in the cooking process of eggplant. The results allow to understand how the inlet energy that impacts on solar cooker is converted in energy useful in the cooking process of eggplant. This work be used in future designs of solar cookers.
Solar Parabolic Dish Annual Technology Evaluation Report
NASA Technical Reports Server (NTRS)
1983-01-01
The activities of the JPL Solar Thermal Power Systems Parabolic Dish Project for FY 1982 are summarized. Included are discussions on designs of module development including their concentrator, receiver, and power conversion subsystems. Analyses and test results, along with progress on field tests, Small Community Experiment System development, and tests at the Parabolic Dish Test Site are also included.
Solar parabolic dish technology evaluation report
NASA Technical Reports Server (NTRS)
Lucas, J. W.
1984-01-01
The activities of the JPL Solar Thermal Power Systems Parabolic Dish Project for FY 1983 are summarized. Included are discussions on designs of module development including concentrator, receiver, and power conversion subsystems together with a separate discussion of field tests, Small Community Experiment system development, and tests at the Parabolic Dish Test Site.
Heat Transfer Convection in The Cooking of Apple Using a Solar Cooker Box-Type
NASA Astrophysics Data System (ADS)
Terres, H.; Chávez, S.; Lizardi, A.; López, R.; Vaca, M.; Flores, J.; Salazar, A.
2015-01-01
In this work, experimental results to determine the convection heat transfer coefficient in the cooking process of apple using a solar cooker box-type are presented. Experimental data of temperatures for water, surface and central point of the apple were used. To determine the convection coefficient, the apple was modelled as a sphere. The temperatures evolution was defined using thermocouples located at water, surface and central point in the vegetables. Using heat transfer convection equations in transitory state and the temperatures measured, the Biot number and the convection coefficient were determined.
Design, fabrication, and testing of a mechanical timer in application of a stored-heat solar cooker
Hsu, Julia C
2014-01-01
There is a large need in third-world tropical areas for a method of cooking in which users need minimal resources and traversing to heat food at night. A solution to this problem is to create a stored-heat solar cooker ...
Solar Thermal Power Systems parabolic dish project
NASA Technical Reports Server (NTRS)
Truscello, V. C.
1981-01-01
The status of the Solar Thermal Power Systems Project for FY 1980 is summarized. Included is: a discussion of the project's goals, program structure, and progress in parabolic dish technology. Analyses and test results of concentrators, receivers, and power converters are discussed. Progress toward the objectives of technology feasibility, technology readiness, system feasibility, and system readiness are covered.
Building a parabolic solar concentrator prototype
NASA Astrophysics Data System (ADS)
Escobar-Romero, J. F. M.; Montiel, S. Vázquez y.; Granados-Agustín, F.; Cruz-Martínez, V. M.; Rodríguez-Rivera, E.; Martínez-Yáńez, L.
2011-01-01
In order to not further degrade the environment, people have been seeking to replace non-renewable natural resources such as fossil fuels by developing technologies that are based on renewable resources. An example of these technologies is solar energy. In this paper, we show the building and test of a solar parabolic concentrator as a prototype for the production of steam that can be coupled to a turbine to generate electricity or a steam engine in any particular industrial process.
Parabolic trough solar collectors : design for increasing efficiency
Figueredo, Stacy L. (Stacy Lee), 1981-
2011-01-01
Parabolic trough collectors are a low cost implementation of concentrated solar power technology that focuses incident sunlight onto a tube filled with a heat transfer fluid. The efficiency and cost of the parabolic trough ...
Parabolic dish collectors - A solar option
NASA Technical Reports Server (NTRS)
Truscello, V. C.
1981-01-01
A description is given of several parabolic-dish high temperature solar thermal systems currently undergoing performance trials. A single parabolic dish has the potential for generating 20 to 30 kW of electricity with fluid temperatures from 300 to 1650 C. Each dish is a complete power-producing unit, and may function either independently or as part of a group of linked modules. The two dish designs under consideration are of 11 and 12 meter diameters, yielding receiver operating temperatures of 925 and 815 C, respectively. The receiver designs described include (1) an organic working fluid (toluene) Rankine cycle engine; (2) a Brayton open cycle unit incorporating a hybrid combustion chamber and nozzle and a shaft-coupled permanent magnet alternator; and (3) a modified Stirling cycle device originally designed for automotive use. Also considered are thermal buffer energy storage and thermochemical transport and storage.
Alignment method for parabolic trough solar concentrators
Diver, Richard B. (Albuquerque, NM)
2010-02-23
A Theoretical Overlay Photographic (TOP) alignment method uses the overlay of a theoretical projected image of a perfectly aligned concentrator on a photographic image of the concentrator to align the mirror facets of a parabolic trough solar concentrator. The alignment method is practical and straightforward, and inherently aligns the mirror facets to the receiver. When integrated with clinometer measurements for which gravity and mechanical drag effects have been accounted for and which are made in a manner and location consistent with the alignment method, all of the mirrors on a common drive can be aligned and optimized for any concentrator orientation.
Steam engine research for solar parabolic dish
NASA Technical Reports Server (NTRS)
Demler, R. L.
1981-01-01
The parabolic dish solar concentrator provides an opportunity to generate high grade energy in a modular system. Most of the capital is projected to be in the dish and its installation. Assurance of a high production demand of a standard dish could lead to dramatic cost reductions. High production volume in turn depends upon maximum application flexibility by providing energy output options, e.g., heat, electricity, chemicals and combinations thereof. Subsets of these options include energy storage and combustion assist. A steam engine design and experimental program is described which investigate the efficiency potential of a small 25 kW compound reheat cycle piston engine. An engine efficiency of 35 percent is estimated for a 700 C steam temperature from the solar receiver.
Proceedings of the Fifth Parabolic Dish Solar Thermal Power Program
NASA Technical Reports Server (NTRS)
Lucas, J. W. (editor)
1984-01-01
The proceedings of the Fifth Parabolic Dish Solar Thermal Power Program Annual Review are presented. The results of activities within the Parabolic Dish Technology and Module/Systems Development element of the Department of Energy's Solar Thermal Energy Systems Program were emphasized. Among the topics discussed were: overall Project and Program aspects, Stirling and Brayton module development, concentrator and engine/receiver development along with associated hardware and test results; distributed systems operating experience; international parabolic dish development activities; and non-DOE-sponsored domestic dish activities. Solar electric generation was also addressed.
Test results, Industrial Solar Technology parabolic trough solar collector
Dudley, V.E.; Evans, L.R.; Matthews, C.W.
1995-11-01
Sandia National Laboratories and Industrial Solar Technology are cost-sharing development of advanced parabolic trough technology. As part of this effort, several configurations of an IST solar collector were tested to determine the collector efficiency and thermal losses with black chrome and black nickel receiver selective coatings, combined with aluminized film and silver film reflectors, using standard Pyrex{reg_sign} and anti-reflective coated Pyrex{reg_sign} glass receiver envelopes. The development effort has been successful, producing an advanced collector with 77% optical efficiency, using silver-film reflectors, a black nickel receiver coating, and a solgel anti-reflective glass receiver envelope. For each receiver configuration, performance equations were empirically derived relating collector efficiency and thermal losses to the operating temperature. Finally, equations were derived showing collector performance as a function of input insolation value, incident angle, and operating temperature.
Federal technology alert. Parabolic-trough solar water heating
1998-04-01
Parabolic-trough solar water heating is a well-proven renewable energy technology with considerable potential for application at Federal facilities. For the US, parabolic-trough water-heating systems are most cost effective in the Southwest where direct solar radiation is high. Jails, hospitals, barracks, and other facilities that consistently use large volumes of hot water are particularly good candidates, as are facilities with central plants for district heating. As with any renewable energy or energy efficiency technology requiring significant initial capital investment, the primary condition that will make a parabolic-trough system economically viable is if it is replacing expensive conventional water heating. In combination with absorption cooling systems, parabolic-trough collectors can also be used for air-conditioning. Industrial Solar Technology (IST) of Golden, Colorado, is the sole current manufacturer of parabolic-trough solar water heating systems. IST has an Indefinite Delivery/Indefinite Quantity (IDIQ) contract with the Federal Energy Management Program (FEMP) of the US Department of Energy (DOE) to finance and install parabolic-trough solar water heating on an Energy Savings Performance Contract (ESPC) basis for any Federal facility that requests it and for which it proves viable. For an ESPC project, the facility does not pay for design, capital equipment, or installation. Instead, it pays only for guaranteed energy savings. Preparing and implementing delivery or task orders against the IDIQ is much simpler than the standard procurement process. This Federal Technology Alert (FTA) of the New Technology Demonstration Program is one of a series of guides to renewable energy and new energy-efficient technologies.
Parabolic Dish Solar Thermal Power Annual Program Review Proceedings
NASA Technical Reports Server (NTRS)
Lucas, J. W.
1982-01-01
The results of activities of the parabolic dish technology and applications development element of DOE's Solar Thermal Energy System Program are presented. Topics include the development and testing of concentrators, receivers, and power conversion units; system design and development for engineering experiments; economic analysis and marketing assessment; and advanced development activities. A panel discussion concerning industrial support sector requirements is also documented.
Gas Turbine/Solar Parabolic Trough Hybrid Designs: Preprint
Turchi, C. S.; Ma, Z.; Erbes, M.
2011-03-01
A strength of parabolic trough concentrating solar power (CSP) plants is the ability to provide reliable power by incorporating either thermal energy storage or backup heat from fossil fuels. Yet these benefits have not been fully realized because thermal energy storage remains expensive at trough operating temperatures and gas usage in CSP plants is less efficient than in dedicated combined cycle plants. For example, while a modern combined cycle plant can achieve an overall efficiency in excess of 55%; auxiliary heaters in a parabolic trough plant convert gas to electricity at below 40%. Thus, one can argue the more effective use of natural gas is in a combined cycle plant, not as backup to a CSP plant. Integrated solar combined cycle (ISCC) systems avoid this pitfall by injecting solar steam into the fossil power cycle; however, these designs are limited to about 10% total solar enhancement. Without reliable, cost-effective energy storage or backup power, renewable sources will struggle to achieve a high penetration in the electric grid. This paper describes a novel gas turbine / parabolic trough hybrid design that combines solar contribution of 57% and higher with gas heat rates that rival that for combined cycle natural gas plants. The design integrates proven solar and fossil technologies, thereby offering high reliability and low financial risk while promoting deployment of solar thermal power.
Beaming-In On Student-Made Solar Technology
ERIC Educational Resources Information Center
Chiotelis, Charles L.
1978-01-01
Completion of a unit on heat energy motivated students to devise their own solar collectors, parabolic solar cookers, and designs for a solar home. Using their solar projects, the students tests hypotheses they might have had concerning heating capacities, insulation values, or energy conversions. (MA)
Cooking with the Sun. How To Build and Use Solar Cookers.
ERIC Educational Resources Information Center
Halacy, Beth; Halacy, Dan
For those working with solar energy and/or conservation and the careful use of resources, constructing a solar oven can be a fun and useful activity. This book describes the construction and use of solar ovens for cooking. Construction details are provided for two inexpensive solar ovens and a reflector hot plate that can then be used to cook 100…
Irrigation market for solar thermal parabolic dish systems
NASA Technical Reports Server (NTRS)
Habib-Agahi, H.; Jones, S. C.
1981-01-01
The potential size of the onfarm-pumped irrigation market for solar thermal parabolic dish systems in seven high-insolation states is estimated. The study is restricted to the displacement of three specific fuels: gasoline, diesel and natural gas. The model was developed to estimate the optimal number of parabolic dish modules per farm based on the minimum cost mix of conventional and solar thermal energy required to meet irrigation needs. The study concludes that the potential market size for onfarm-pumped irrigation applications ranges from 101,000 modules when a 14 percent real discount rate is assumed to 220,000 modules when the real discount rate drops to 8 percent. Arizona, Kansas, Nebraska, New Mexico and Texas account for 98 percent of the total demand for this application, with the natural gas replacement market accounting for the largest segment (71 percent) of the total market.
Absorber Alignment Measurement Tool for Solar Parabolic Trough Collectors: Preprint
Stynes, J. K.; Ihas, B.
2012-04-01
As we pursue efforts to lower the capital and installation costs of parabolic trough solar collectors, it is essential to maintain high optical performance. While there are many optical tools available to measure the reflector slope errors of parabolic trough solar collectors, there are few tools to measure the absorber alignment. A new method is presented here to measure the absorber alignment in two dimensions to within 0.5 cm. The absorber alignment is measured using a digital camera and four photogrammetric targets. Physical contact with the receiver absorber or glass is not necessary. The alignment of the absorber is measured along its full length so that sagging of the absorber can be quantified with this technique. The resulting absorber alignment measurement provides critical information required to accurately determine the intercept factor of a collector.
Proceedings: Fourth Parabolic Dish Solar Thermal Power Program Review
NASA Technical Reports Server (NTRS)
1983-01-01
The results of activities within the parabolic dish technology and applications development program are presented. Stirling, organic Rankine and Brayton module technologies, associated hardware and test results to date; concentrator development and progress; economic analyses; and international dish development activities are covered. Two panel discussions, concerning industry issues affecting solar thermal dish development and dish technology from a utility/user perspective, are also included.
Secondary concentrators for parabolic dish solar thermal power systems
NASA Technical Reports Server (NTRS)
Jaffe, L. D.; Poon, P. T.
1981-01-01
A variety of different concepts are currently being studied with the objective to lower the cost of parabolic mirrors and to provide alternatives. One of the considered approaches involves the use of compound concentrators. A compound solar concentrator is a concentrator in which the sunlight is reflected or refracted more than once. It consists of a primary mirror or lens, whose aperture determines the amount of sunlight gathered, and a smaller secondary mirror or lens. Additional small optical elements may also be incorporated. The possibilities and problems regarding a use of compound concentrators in parabolic dish systems are discussed. Attention is given to concentrating secondary lenses, secondary imaging and concentrating mirrors, conical secondary mirrors, compound elliptic secondary concentrating mirrors, and hyperbolic trumpet secondary concentrating mirrors.
Thermal storage requirements for parabolic dish solar power plants
NASA Technical Reports Server (NTRS)
Wen, L.; Steele, H.
1980-01-01
The cost effectiveness of a high temperature thermal storage system is investigated for a representative parabolic dish solar power plant. The plant supplies electrical power in accordance with a specific, seasonally varying demand profile. The solar power received by the plant is supplemented by power from fuel combustion. The cost of electricity generated by the solar power plant is calculated, using the cost of mass-producible subsystems (specifically, parabolic dishes, receivers, and power conversion units) now being designed for this type of solar plant. The trade-off between fuel and thermal storage is derived in terms of storage effectiveness, the cost of storage devices, and the cost of fuel. Thermal storage requirements, such as storage capacity, storage effectiveness, and storage cost are established based on the cost of fuel and the overall objective of minimizing the cost of the electricity produced by the system. As the cost of fuel increases at a rate faster than general inflation, thermal storage systems in the $40 to $70/kWthr range could become cost effective in the near future.
Exergetic analysis of parabolic trough solar thermal power plants
NASA Astrophysics Data System (ADS)
Petrakopoulou, F.; Ruperez, B.; San Miguel, G.
2014-12-01
A very important component to achieve sustainable development in the energy sector is the improvement of energy efficiency of widely applied thermodynamic processes. Evaluation and optimization methods of energy processes play a crucial role in fulfilling this goal. A suitable method for the evaluation and optimization of energy conversion systems has been proven to be the exergetic analysis. In this work, two parabolic trough solar thermal power plants are simulated in detail using commercial software, and they are further analysed and compared using an exergetic analysis. The first plant uses a thermal fluid to produce the steam required in a steam generator, while the second one produces the steam directly in the solar field. The analysis involves the evaluation of the individual components of the power plants, as well as the performance evaluation of the overall structures. The main goal is to detect thermodynamic inefficiencies of the two different configurations and propose measures to minimize those. We find that the two examined plants have similar main sources of exergy destruction: the solar field (parabolic trough solar collectors), followed by the steam generator. This reveals the importance of an optimal design of these particular components, which could reduce inefficiencies present in the system. The differences in the exergy destruction and exergetic efficiencies of individual components of the two plants are analyzed in detail based on comparable operational conditions.
Fifth parabolic dish solar thermal power program annual review: proceedings
1984-03-01
The primary objective of the Review was to present the results of activities within the Parabolic Dish Technology and Module/Systems Development element of the Department of Energy's Solar Thermal Energy Systems Program. The Review consisted of nine technical sessions covering overall Project and Program aspects, Stirling and Brayton module development, concentrator and engine/receiver development, and associated hardware and test results to date; distributed systems operating experience; international dish development activities; and non-DOE-sponsored domestic dish activities. A panel discussion concerning business views of solar electric generation was held. These Proceedings contain the texts of presentations made at the Review, as submitted by their authors at the beginning of the Review; therefore, they may vary slightly from the actual presentations in the technical sessions.
Solar parabolic dish thermal power systems - Technology and applications
NASA Technical Reports Server (NTRS)
Lucas, J. W.; Marriott, A. T.
1979-01-01
Activities of two projects at JPL in support of DOE's Small Power Systems Program are reported. These two projects are the Point-Focusing Distributed Receiver (PFDR) Technology Project and the Point-Focusing Thermal and Electric Applications (PFTEA) Project. The PFDR Technology Project's major activity is developing the technology of solar concentrators, receivers and power conversion subsystems suitable for parabolic dish or point-focusing distributed receiver power systems. Other PFDR activities include system integration and cost estimation under mass production, as well as the testing of the hardware. The PFTEA Project's first major activity is applications analysis, that is seeking ways to introduce PFDR systems into appropriate user sectors. The second activity is systems engineering and development wherein power plant systems are analyzed for specific applications. The third activity is the installation of a series of engineering experiments in various user environments to obtain actual operating experience
Mullick, S.C.; Kandpal, T.C.; Kumar, S.
1996-11-01
The performance of a box-type solar cooker can be represented in terms of two figures of merit, F{sub 1} and F{sub 2}. The second figure F{sub 2} is a controlling factor in the sensible heating of a load. The present work validates F{sub 2} by computing this figure from experimental data by two different procedures and comparing the results. An attempt has also been made to provide some guidelines for selecting a suitable temperature interval for determination of F{sub 2}. The results of some experiments to study the effect of number of pots and the load on F{sub 2} have also been presented. It is recommended that for standardization tests should be conducted at full load. 2 refs., 7 figs., 2 tabs.
Mechanism of Hydrogen Formation in Solar Parabolic Trough Receivers
Moens, L.; Blake, D. M.
2008-03-01
Solar parabolic trough systems for electricity production are receiving renewed attention, and new solar plants are under construction to help meet the growing demands of the power market in the Western United States. The growing solar trough industry will rely on operating experience it has gained over the last two decades. Recently, researchers found that trough plants that use organic heat transfer fluids (HTF) such as Therminol VP-1 are experiencing significant heat losses in the receiver tubes. The cause has been traced back to the accumulation of excess hydrogen gas in the vacuum annulus that surrounds the steel receiver tube, thus compromising the thermal insulation of the receiver. The hydrogen gas is formed during the thermal decomposition of the organic HTF that circulates inside the receiver loop, and the installation of hydrogen getters inside the annulus has proven to be insufficient for controlling the hydrogen build-up over the lifetime of the receivers. This paper will provide an overview of the chemical literature dealing with the thermal decomposition of diphenyl oxide and biphenyl, the two constituents of Therminol VP-1.
Wind Tunnel Tests of Parabolic Trough Solar Collectors: March 2001--August 2003
Hosoya, N.; Peterka, J. A.; Gee, R. C.; Kearney, D.
2008-05-01
Conducted extensive wind-tunnel tests on parabolic trough solar collectors to determine practical wind loads applicable to structural design for stress and deformation, and local component design for concentrator reflectors.
The parabolic trough power plants Andasol 1 to 3 The largest solar power plants in the world
Laughlin, Robert B.
The parabolic trough power plants Andasol 1 to 3 The largest solar power plants in the world and solar-thermal power plants The first parabolic trough power plants in Europe the world's largest solar power plants: Andasol 1 to 3 Regulatory framework in Spain Project partners 4 8 20 22 #12;4 Solar energy
Slope Error Measurement Tool for Solar Parabolic Trough Collectors: Preprint
Stynes, J. K.; Ihas, B.
2012-04-01
The National Renewable Energy Laboratory (NREL) has developed an optical measurement tool for parabolic solar collectors that measures the combined errors due to absorber misalignment and reflector slope error. The combined absorber alignment and reflector slope errors are measured using a digital camera to photograph the reflected image of the absorber in the collector. Previous work using the image of the reflection of the absorber finds the reflector slope errors from the reflection of the absorber and an independent measurement of the absorber location. The accuracy of the reflector slope error measurement is thus dependent on the accuracy of the absorber location measurement. By measuring the combined reflector-absorber errors, the uncertainty in the absorber location measurement is eliminated. The related performance merit, the intercept factor, depends on the combined effects of the absorber alignment and reflector slope errors. Measuring the combined effect provides a simpler measurement and a more accurate input to the intercept factor estimate. The minimal equipment and setup required for this measurement technique make it ideal for field measurements.
Modeling of a Parabolic Trough Solar Field for Acceptance Testing: A Case Study
Wagner, M. J.; Mehos, M. S.; Kearney, D. W.; McMahan, A. C.
2011-01-01
As deployment of parabolic trough concentrating solar power (CSP) systems ramps up, the need for reliable and robust performance acceptance test guidelines for the solar field is also amplified. Project owners and/or EPC contractors often require extensive solar field performance testing as part of the plant commissioning process in order to ensure that actual solar field performance satisfies both technical specifications and performance guaranties between the involved parties. Performance test code work is currently underway at the National Renewable Energy Laboratory (NREL) in collaboration with the SolarPACES Task-I activity, and within the ASME PTC-52 committee. One important aspect of acceptance testing is the selection of a robust technology performance model. NREL1 has developed a detailed parabolic trough performance model within the SAM software tool. This model is capable of predicting solar field, sub-system, and component performance. It has further been modified for this work to support calculation at subhourly time steps. This paper presents the methodology and results of a case study comparing actual performance data for a parabolic trough solar field to the predicted results using the modified SAM trough model. Due to data limitations, the methodology is applied to a single collector loop, though it applies to larger subfields and entire solar fields. Special consideration is provided for the model formulation, improvements to the model formulation based on comparison with the collected data, and uncertainty associated with the measured data. Additionally, this paper identifies modeling considerations that are of particular importance in the solar field acceptance testing process and uses the model to provide preliminary recommendations regarding acceptable steady-state testing conditions at the single-loop level.
Code of Federal Regulations, 2013 CFR
2013-01-01
...accessible for cleaning. Each cooker shall be equipped with an indicating thermometer, and shall be equipped with a temperature recording device. The recording thermometer stem may be placed in the cooker if satisfactory time charts are...
Code of Federal Regulations, 2010 CFR
2010-01-01
...accessible for cleaning. Each cooker shall be equipped with an indicating thermometer, and shall be equipped with a temperature recording device. The recording thermometer stem may be placed in the cooker if satisfactory time charts are...
Code of Federal Regulations, 2014 CFR
2014-01-01
...accessible for cleaning. Each cooker shall be equipped with an indicating thermometer, and shall be equipped with a temperature recording device. The recording thermometer stem may be placed in the cooker if satisfactory time charts are...
Code of Federal Regulations, 2011 CFR
2011-01-01
...accessible for cleaning. Each cooker shall be equipped with an indicating thermometer, and shall be equipped with a temperature recording device. The recording thermometer stem may be placed in the cooker if satisfactory time charts are...
Code of Federal Regulations, 2012 CFR
2012-01-01
...accessible for cleaning. Each cooker shall be equipped with an indicating thermometer, and shall be equipped with a temperature recording device. The recording thermometer stem may be placed in the cooker if satisfactory time charts are...
Code of Federal Regulations, 2010 CFR
2010-01-01
... cleaning. Each cooker shall be equipped with an indicating thermometer, and shall be equipped with a temperature recording device. The recording thermometer stem may be placed in the cooker if satisfactory...
Code of Federal Regulations, 2011 CFR
2011-01-01
... cleaning. Each cooker shall be equipped with an indicating thermometer, and shall be equipped with a temperature recording device. The recording thermometer stem may be placed in the cooker if satisfactory...
Code of Federal Regulations, 2014 CFR
2014-01-01
... cleaning. Each cooker shall be equipped with an indicating thermometer, and shall be equipped with a temperature recording device. The recording thermometer stem may be placed in the cooker if satisfactory...
Code of Federal Regulations, 2012 CFR
2012-01-01
... cleaning. Each cooker shall be equipped with an indicating thermometer, and shall be equipped with a temperature recording device. The recording thermometer stem may be placed in the cooker if satisfactory...
Ferreira, Toni (Toni Jolene)
2005-01-01
An experimental study was performed to test the effectiveness of design modifications terms of efficiency and power production in an existing parabolic solar concentrator. The proposed modifications included limiting the ...
Recent Solar Measurements Results at the Parabolic Dish Test Site
NASA Technical Reports Server (NTRS)
Ross, D. L.
1984-01-01
After the Mexican volcanic eruptions of March 28, April 3 and 4, 1982, the question of its effect on insolation levels at the Parabolic Dish Test Site (PDTS) naturally arose. Clearly, the answer to the original question is that the Mexican volcanic explosion had a significant impact on energy and insolation levels at the PDTS and, furthermore, it has been quite long lasting. The first really significant decrease in energy and insolation levels occurred in June 1982 when the energy level decreased by 19.7% while the peak insolation levels went down by 4.0%. June of 1982 was also the first month (of 13 consecutive months) when peak insolation levels did not equal or exceed 1,000 W/sq m. Signs of a recovery from the effects of the volcanic explosion began to appear in May of 1983, when the energy level exceeded that of May 1981 as well as May 1982. It would appear that energy and insolation levels are improving at the PDTS, but have not quite reached normal or pre-volcanic levels. At this time the data would seem to suggest a return to normal energy and insolation levels will occur in the very near future.
Gas Turbine/Solar Parabolic Trough Hybrid Design Using Molten Salt Heat Transfer Fluid: Preprint
Turchi, C. S.; Ma, Z.
2011-08-01
Parabolic trough power plants can provide reliable power by incorporating either thermal energy storage (TES) or backup heat from fossil fuels. This paper describes a gas turbine / parabolic trough hybrid design that combines a solar contribution greater than 50% with gas heat rates that rival those of natural gas combined-cycle plants. Previous work illustrated benefits of integrating gas turbines with conventional oil heat-transfer-fluid (HTF) troughs running at 390?C. This work extends that analysis to examine the integration of gas turbines with salt-HTF troughs running at 450 degrees C and including TES. Using gas turbine waste heat to supplement the TES system provides greater operating flexibility while enhancing the efficiency of gas utilization. The analysis indicates that the hybrid plant design produces solar-derived electricity and gas-derived electricity at lower cost than either system operating alone.
A Linear Parabolic Trough Solar Collector Performance Model
Qu, M.; Archer, D.; Masson, S.
2006-01-01
Collector (PTSC). This steady state, single dimensional model comprises the fundamental radiative and convective heat transfer and mass and energy balance relations programmed in the Engineering Equation Solver, EES. It considers the effects of solar...
NASA Astrophysics Data System (ADS)
Harrigan, R. W.
1981-07-01
This report presents the techniques needed to execute conceptual designs of process heat systems employing parabolic trough solar collectors. The design tools are presented in graphical format, and each of 26 SOLMET sites is explicitly represented. The conceptual design resultant from the application of the design charts contained within this handbook approximates the collector area needed to displace a constant thermal demand, the land area needed for collector deployment, the appropriate quantity of sensible heat storage, the fraction of fossil fuel displaced by solar, and the capital cost of the collector-storage subsystem.
Thermal buffering of receivers for parabolic dish solar thermal power plants
NASA Technical Reports Server (NTRS)
Manvi, R.; Fujita, T.; Gajanana, B. C.; Marcus, C. J.
1980-01-01
A parabolic dish solar thermal power plant comprises a field of parabolic dish power modules where each module is composed of a two-axis tracking parabolic dish concentrator which reflects sunlight (insolation) into the aperture of a cavity receiver at the focal point of the dish. The heat generated by the solar flux entering the receiver is removed by a heat transfer fluid. In the dish power module, this heat is used to drive a small heat engine/generator assembly which is directly connected to the cavity receiver at the focal point. A computer analysis is performed to assess the thermal buffering characteristics of receivers containing sensible and latent heat thermal energy storage. Parametric variations of the thermal inertia of the integrated receiver-buffer storage systems coupled with different fluid flow rate control strategies are carried out to delineate the effect of buffer storage, the transient response of the receiver-storage systems and corresponding fluid outlet temperature. It is concluded that addition of phase change buffer storage will substantially improve system operational characteristics during periods of rapidly fluctuating insolation due to cloud passage.
Cost/performance of solar reflective surfaces for parabolic dish concentrators
NASA Technical Reports Server (NTRS)
Bouquet, F.
1980-01-01
Materials for highly reflective surfaces for use in parabolic dish solar concentrators are discussed. Some important factors concerning performance of the mirrors are summarized, and typical costs are treated briefly. Capital investment cost/performance ratios for various materials are computed specifically for the double curvature parabolic concentrators using a mathematical model. The results are given in terms of initial investment cost for reflective surfaces per thermal kilowatt delivered to the receiver cavity for various operating temperatures from 400 to 1400 C. Although second surface glass mirrors are emphasized, first surface, chemically brightened and anodized aluminum surfaces as well as second surface, metallized polymeric films are treated. Conventional glass mirrors have the lowest cost/performance ratios, followed closely by aluminum reflectors. Ranges in the data due to uncertainties in cost and mirror reflectance factors are given.
Convection heat loss from cavity receiver in parabolic dish solar thermal power system: A review
Wu, Shuang-Ying; Xiao, Lan; Li, You-Rong; Cao, Yiding
2010-08-15
The convection heat loss from cavity receiver in parabolic dish solar thermal power system can significantly reduce the efficiency and consequently the cost effectiveness of the system. It is important to assess this heat loss and subsequently improve the thermal performance of the receiver. This paper aims to present a comprehensive review and systematic summarization of the state of the art in the research and progress in this area. The efforts include the convection heat loss mechanism, experimental and numerical investigations on the cavity receivers with varied shapes that have been considered up to date, and the Nusselt number correlations developed for convection heat loss prediction as well as the wind effect. One of the most important features of this paper is that it has covered numerous cavity literatures encountered in various other engineering systems, such as those in electronic cooling devices and buildings. The studies related to those applications may provide valuable information for the solar receiver design, which may otherwise be ignored by a solar system designer. Finally, future development directions and the issues that need to be further investigated are also suggested. It is believed that this comprehensive review will be beneficial to the design, simulation, performance assessment and applications of the solar parabolic dish cavity receivers. (author)
Unknown
2011-08-17
This report is a detailed overview of my research on solar water heating. Solar water heaters may be used to either supplement or even replace a standard water heater. In addition to being environmentally friendly, solar heaters can save a homeowner...
NASA Astrophysics Data System (ADS)
Muhlen, Luis S. W.; Najafi, Behzad; Rinaldi, Fabio; Marchesi, Renzo
2014-04-01
Solar troughs are amongst the most commonly used technologies for collecting solar thermal energy and any attempt to increase the performance of these systems is welcomed. In the present study a parabolic solar trough is simulated using a one dimensional finite element model in which the energy balances for the fluid, the absorber and the envelope in each element are performed. The developed model is then validated using the available experimental data . A sensitivity analysis is performed in the next step in order to study the effect of changing the type of the working fluid and the corresponding Reynolds number on the overall performance of the system. The potential improvement due to the addition of a shield on the upper half of the annulus and enhancing the convection coefficient of the heat transfer fluid is also studied.
NASA Technical Reports Server (NTRS)
Ramakumar, R.; Bahrami, K.
1981-01-01
This paper discusses the application of field modulated generator systems (FMGS) to dispersed solar-thermal-electric generation from a parabolic dish field with electric transport. Each solar generation unit is rated at 15 kWe and the power generated by an array of such units is electrically collected for insertion into an existing utility grid. Such an approach appears to be most suitable when the heat engine rotational speeds are high (greater than 6000 r/min) and, in particular, if they are operated in the variable speed mode and if utility-grade a.c. is required for direct insertion into the grid without an intermediate electric energy storage and reconversion system. Predictions of overall efficiencies based on conservative efficiency figures for the FMGS are in the range of 25 per cent and should be encouraging to those involved in the development of cost-effective dispersed solar thermal power systems.
Optical analysis of parabolic dish concentrators for solar dynamic power systems in space
NASA Technical Reports Server (NTRS)
Jefferies, K. S.
1985-01-01
An optical analysis of a parabolic solar collection system operating in Earth orbit was performed using ray tracing techniques. The analysis included the effects of: (1) solar limb darkening, (2) parametric variation of mirror surface error, (3) parametric variation of mirror rim angle, and (4) parametric variation of alignment and pointing error. This ray tracing technique used numerical integration to combine the effects of rays emanating from different parts of the sun at different intensities with the effects of normally distributed mirror-surface errors to compute the angular intensity distribution of rays leaving the mirror surface. A second numerical integration was then performed over the surface of the parabolic mirror to compute the radial distribution of brightness at the mirror focus. Major results of the analysis included: (1) solar energy can be collected at high temperatures with high efficiency, (2) higher absorber temperatures can be achieved at lower efficiencies, or higher efficiencies can be achieved at lower temperatures, and (3) collection efficiency is near its maximum level across a broad plateau of rim angles from 40 deg to 70 deg.
Test results on parabolic dish concentrators for solar thermal power systems
NASA Technical Reports Server (NTRS)
Jaffe, Leonard D.
1989-01-01
This paper presents results of development testing of various solar thermal parabolic dish concentrators. The concentrators were mostly designed for the production of electric power using dish-mounted Rankine, Brayton or Stirling cycle engines, intended to be produced at low cost. Measured performance for various dishes included optical efficiencies ranging from 0.32 to 0.86 at a geometric concentration ratio of 500, and from about 0.09 to 0.85 at a geometric concentration ratio of 3000. Some malfunctions were observed. The tests should provide operating information of value in developing concentrators with improved performance and reduced maintenance.
Parabolic Trough Reference Plant for Cost Modeling with the Solar Advisor Model (SAM)
Turchi, C.
2010-07-01
This report describes a component-based cost model developed for parabolic trough solar power plants. The cost model was developed by the National Renewable Energy Laboratory (NREL), assisted by WorleyParsons Group Inc., for use with NREL's Solar Advisor Model (SAM). This report includes an overview and explanation of the model, two summary contract reports from WorleyParsons, and an Excel spreadsheet for use with SAM. The cost study uses a reference plant with a 100-MWe capacity and six hours of thermal energy storage. Wet-cooling and dry-cooling configurations are considered. The spreadsheet includes capital and operating cost by component to allow users to estimate the impact of changes in component costs.
Summary assessment of solar thermal parabolic dish technology for electrical power generation
NASA Technical Reports Server (NTRS)
Penda, P. L.; Fujita, T.; Lucas, J. W.
1985-01-01
An assessment is provided of solar thermal parabolic dish technology for electrical power generation. The assessment is based on the development program undertaken by the Jet Propulsion Laboratory for the U.S. Department of Energy and covers the period from the initiation of the program in 1976 through mid-1984. The program was founded on developing components and subsystems that are integrated into parabolic dish power modules for test and evaluation. The status of the project is summarized in terms of results obtained through testing of modules, and the implications of these findings are assessed in terms of techno-economic projections and market potential. The techno-economic projections are based on continuation of an evolutionary technological development program and are related to the accomplishments of the program as of mid-1984. The accomplishments of the development effort are summarized for each major subsystem including concentrators, receivers, and engines. The ramifications of these accomplishments are assessed in the context of developmental objectives and strategies.
Thermal Modeling of a Hybrid Thermoelectric Solar Collector with a Compound Parabolic Concentrator
NASA Astrophysics Data System (ADS)
Lertsatitthanakorn, C.; Jamradloedluk, J.; Rungsiyopas, M.
2013-07-01
In this study radiant light from the sun is used by a hybrid thermoelectric (TE) solar collector and a compound parabolic concentrator (CPC) to generate electricity and thermal energy. The hybrid TE solar collector system described in this report is composed of transparent glass, an air gap, an absorber plate, TE modules, a heat sink to cool the water, and a storage tank. Incident solar radiation falls on the CPC, which directs and reflects the radiation to heat up the absorber plate, creating a temperature difference across the TE modules. The water, which absorbs heat from the hot TE modules, flows through the heat sink to release its heat. The results show that the electrical power output and the conversion efficiency depend on the temperature difference between the hot and cold sides of the TE modules. A maximum power output of 1.03 W and a conversion efficiency of 0.6% were obtained when the temperature difference was 12°C. The thermal efficiency increased as the water flow rate increased. The maximum thermal efficiency achieved was 43.3%, corresponding to a water flow rate of 0.24 kg/s. These experimental results verify that using a TE solar collector with a CPC to produce both electrical power and thermal energy seems to be feasible. The thermal model and calculation method can be applied for performance prediction.
Comparison of electrochemical and thermal storage for hybrid parabolic dish solar power plants
NASA Technical Reports Server (NTRS)
Steele, H. L.; Wen, L.
1981-01-01
The economic and operating performance of a parabolic point focus array of solar electricity generators combined with either battery or thermal energy storage are examined. Noting that low-cost, mass-producible power generating units are under development for the point focus of distributed dishes, that Zn-Cl battery tests will begin in 1981 and a 100 kWh Na-S battery in 1983, the state of thermal storage requires acceleration to reach the prototype status of the batteries. Under the assumptions of 10,000 units/yr with an expected 30 yr lifetime, cost comparisons are developed for 10 types of advanced batteries. A 5 MWe plant with full thermal or 80% battery storage discharge when demand occurs in conditions of no insolation is considered, specifically for Fe-Cr redox batteries. A necessity for the doubling of fuel prices from 1980 levels by 1990 is found in order to make the systems with batteries economically competitive.
Kearney, D.
2011-05-01
Prior to commercial operation, large solar systems in utility-size power plants need to pass a performance acceptance test conducted by the engineering, procurement, and construction (EPC) contractor or owners. In lieu of the present absence of ASME or other international test codes developed for this purpose, the National Renewable Energy Laboratory has undertaken the development of interim guidelines to provide recommendations for test procedures that can yield results of a high level of accuracy consistent with good engineering knowledge and practice. The Guidelines contained here are specifically written for parabolic trough collector systems with a heat-transport system using a high-temperature synthetic oil, but the basic principles are relevant to other CSP systems.
NASA Technical Reports Server (NTRS)
1982-01-01
The essential elements of the cogeneration system configuration to be captured were the displacement of thermal energy by collection and use of the Brayton exhaust stream, and the sale back to the utility of any electricity production in excess of on-site requirements. In contrast to simply dumping these energy flows, their use or sale obviously serves, by itself, to increase gross value of the solar thermal energy system. Net allowable cost of the parabolic dish modules may or may not be increased, however. A consideration is that the waste heat capture and delivery subsystems are not free. This study does not address the incremental cost of adding waste heat capture, transport, and conversion (to steam, if necessary). It does compute a value for the thermal energy thereby displaced. This value can serve as a first-round input to any detailed economic evaluation of waste heat recovery.
Highly efficient end-side-pumped Nd:YAG solar laser by a heliostat-parabolic mirror system.
Almeida, J; Liang, D; Vistas, C R; Guillot, E
2015-03-10
We report a large improvement in the collection and slope efficiency of an Nd:YAG solar laser pumped by a heliostat-parabolic mirror system. A conical fused silica lens was used to further concentrate the solar radiation from the focal zone of a 2 m diameter primary concentrator to a Nd:YAG single-crystal rod within a conical pump cavity, which enabled multipass pumping to the active medium. A 56 W cw laser power was measured, corresponding to 21.1??W/m2 record-high solar laser collection efficiency with the heliostat-parabolic mirror system. 4.9% slope efficiency was calculated, corresponding to 175% enhancement over our previous result. PMID:25968373
Washom, B.J.
1984-09-30
Advanco Corporation and the US Department of Energy entered into a cooperative agreement in May 1982 for the design, manufacture, and test of a 25-kWe solar parabolic dish module utilizing a Stirling engine power conversion unit. The product of the cooperative agreement is the Vanguard solar parabolic dish-Stirling engine module. It was designed, fabricated, and shop assembled in Los Angeles, California, and Malmoe, Sweden, and was then installed and tested at Rancho Mirage, California, in accordance with the agreement's specifications. The design features simple fabrication and assembly techniques, low cost, and high operating efficiency. The cover displays the Vanguard module operating on-sun. The concept combines the United Stirling AB (USAB) 4-95 Solar II Stirling engine, the Jet Propulsion Laboratory (JPL) developed mirror facets, the Rockwell/Advanco exocentric gimbal mechanism (EGM), the advanced USAB receiver, and a dry, integrated heat rejection system.
NASA Astrophysics Data System (ADS)
Polzien, R. E.; Rodriguez, D.
1981-04-01
Aspects of incorporating a thermal energy transport system (ETS) into a field of parabolic dish collectors for industrial process heat (IPH) applications were investigated. Specific objectives are to: (1) verify the mathematical optimization of pipe diameters and insulation thicknesses calculated by a computer code; (2) verify the cost model for pipe network costs using conventional pipe network construction; (3) develop a design and the associated production costs for incorporating risers and downcomers on a low cost concentrator (LCC); (4) investigate the cost reduction of using unconventional pipe construction technology. The pipe network design and costs for a particular IPH application, specifically solar thermally enhanced oil recovery (STEOR) are analyzed. The application involves the hybrid operation of a solar powered steam generator in conjunction with a steam generator using fossil fuels to generate STEOR steam for wells. It is concluded that the STEOR application provides a baseline pipe network geometry used for optimization studies of pipe diameter and insulation thickness, and for development of comparative cost data, and operating parameters for the design of riser/downcomer modifications to the low cost concentrator.
Numerical Modeling of Year-Round Performance of a Solar Parabolic Dish Thermoelectric Generator
NASA Astrophysics Data System (ADS)
Muthu, G.; Shanmugam, S.; Veerappan, AR.
2015-08-01
This paper presents the year-round performance of a solar parabolic dish thermoelectric generator under different values of operating parameters such as ambient temperature, wind velocity, direct normal irradiation, and water inlet temperature to the heat sink. The solar thermoelectric generator (TEG) is examined for an Indian location of Tiruchirappalli. The electrical power output and TEG efficiency are maximum during the months of April and August, while they are minimum during the month of December. It is found that the monthly average hot-side temperature of the TEG varies from 556.53 K to 592.68 K and the cold-side temperature of the TEG varies from 413.21 K to 438.91 K. When the hot-side temperature reaches the optimum value, the conversion efficiency is reduced, although the power increases. A TEG model is useful to find the temperature of the junctions for different operating parameter values and predict the performance of the TEG at any time. A small standalone power-generating system using this technology is a promising option.
Headley, O.StC.; Kothdiwala, A.F.; McDoom, I.A. )
1994-08-01
A compound parabolic concentrating solar collector (CPC) of concentration ratio 3.9 and aperture area 2.0 m[sup 2] was used to power an intermittent solid adsorption refrigerator and ice maker using activated charcoal (carbon) as the adsorbing medium and methanol as the working fluid. The copper tube receiver of the CPC was packed with 2.5 kg of imported adsorbent 207E3, which was only utilized when the performance of activated charcoal (ACJ1, produced from local coconut shells) was found to be inferior to the imported adsorbent. Up to 1 kg of ice at an evaporator temperature of [minus]6[degrees]C was produced, with the net solar coefficient of performance (COP) being of the order of 0.02. Maximum receiver/adsorbent temperature recorded was 154[degrees]C on a day when the insolation was 26.8 MJ/m[sup [minus]2]. Temperatures in excess of 150[degrees]C are undesirable since they favour the conversion of methanol to dimethyl ether, a noncondensable gas which inhibits both condensation and adsorption. The major advantage of this system is its ability to produce ice even on overcast days (insolation [approximately] 10 MJ/m[sup [minus]2]).
NASA Technical Reports Server (NTRS)
Polzien, R. E.; Rodriguez, D.
1981-01-01
Aspects of incorporating a thermal energy transport system (ETS) into a field of parabolic dish collectors for industrial process heat (IPH) applications were investigated. Specific objectives are to: (1) verify the mathematical optimization of pipe diameters and insulation thicknesses calculated by a computer code; (2) verify the cost model for pipe network costs using conventional pipe network construction; (3) develop a design and the associated production costs for incorporating risers and downcomers on a low cost concentrator (LCC); (4) investigate the cost reduction of using unconventional pipe construction technology. The pipe network design and costs for a particular IPH application, specifically solar thermally enhanced oil recovery (STEOR) are analyzed. The application involves the hybrid operation of a solar powered steam generator in conjunction with a steam generator using fossil fuels to generate STEOR steam for wells. It is concluded that the STEOR application provides a baseline pipe network geometry used for optimization studies of pipe diameter and insulation thickness, and for development of comparative cost data, and operating parameters for the design of riser/downcomer modifications to the low cost concentrator.
Code of Federal Regulations, 2013 CFR
2013-01-01
... temperature recording device. The recording thermometer stem may be placed in the cooker if satisfactory time charts are obtained, if not, the stem shall be placed in the hotwell or filler hopper. Steam check...
Secondary and compound concentrators for parabolic-dish solar-thermal power systems
Jaffe, L.D.; Poon, P.T.
1981-04-15
A secondary optical element may be added to a parabolic dish solar concentrator to increase the geometric concentration ratio attainable at a given intercept factor. This secondary may be a Fresnel lens or a mirror, such as a compound elliptic concentrator or a hyperbolic trumpet. At a fixed intercept factor, higher overall geometric concentration may be obtainable with a long focal length primary and a suitable secondary matched to it. Use of a secondary to increase the geometric concentration ratio is more likely to be worthwhile if the receiver temperature is high and if errors in the primary are large. Folding the optical path with a secondary may reduce cost by locating the receiver and power conversion equipment closer to the ground and by eliminating the heavy structure needed to support this equipment at the primary focus. Promising folded-path configurations include the Ritchey-Chretien and perhaps some three-element geometries. Folding the optical path may be most useful in systems that provide process heat.
Software used with the flux mapper at the solar parabolic dish test site
NASA Technical Reports Server (NTRS)
Miyazono, C.
1984-01-01
Software for data archiving and data display was developed for use on a Digital Equipment Corporation (DEC) PDP-11/34A minicomputer for use with the JPL-designed flux mapper. The flux mapper is a two-dimensional, high radiant energy scanning device designed to measure radiant flux energies expected at the focal point of solar parabolic dish concentrators. Interfacing to the DEC equipment was accomplished by standard RS-232C serial lines. The design of the software was dicated by design constraints of the flux-mapper controller. Early attemps at data acquisition from the flux-mapper controller were not without difficulty. Time and personnel limitations result in an alternative method of data recording at the test site with subsequent analysis accomplished at a data evaluation location at some later time. Software for plotting was also written to better visualize the flux patterns. Recommendations for future alternative development are discussed. A listing of the programs used in the anaysis is included in an appendix.
Comparison of advanced thermal and electrical storage for parabolic dish solar thermal power systems
NASA Technical Reports Server (NTRS)
Fujita, T.; Birur, G. C.; Schredder, J. M.; Bowyer, J. M.; Awaya, H. I.
1982-01-01
Parabolic dish solar concentrator cluster concepts are explored, with attention given to thermal storage systems coupled to Stirling and Brayton cycle power conversion devices. Sensible heat storage involving molten salt (NaOH), liquid sodium, and solid cordierite bricks are considered for 1500 F thermal storage systems. Latent heat storage with NaF-MgF2 phase change materials are explored in terms of passive, active, and direct contact designs. Comparisons are made of the effectiveness of thermal storage relative to redox, Na-S, Zn-Cl, and Zn-Br battery storage systems. Molten lead trickling down through a phase change eutectic, the NaF-MgF2, formed the direct contact system. Heat transport in all systems is effected through Inconel pipes. Using a cost goal of 120-150 mills/kWh as the controlling parameter, sensible heat systems with molten salts transport with either Stirling or Brayton engines, or latent heat systems with Stirling engines, and latent heat-Brayton engine with direct contact were favored in the analyses. Battery storage systems, however, offered the most flexibility of applications.
Secondary and compound concentrators for parabolic dish solar thermal power systems
NASA Technical Reports Server (NTRS)
Jaffe, L. D.; Poon, P. T.
1981-01-01
A secondary optical element may be added to a parabolic dish solar concentrator to increase the geometric concentration ratio attainable at a given intercept factor. This secondary may be a Fresnel lens or a mirror, such as a compound elliptic concentrator or a hyperbolic trumpet. At a fixed intercept factor, higher overall geometric concentration may be obtainable with a long focal length primary and a suitable secondary matched to it. Use of a secondary to increase the geometric concentration ratio is more likely to e worthwhile if the receiver temperature is high and if errors in the primary are large. Folding the optical path with a secondary may reduce cost by locating the receiver and power conversion equipment closer to the ground and by eliminating the heavy structure needed to support this equipment at the primary focus. Promising folded-path configurations include the Ritchey-Chretien and perhaps some three element geometries. Folding the optical path may be most useful in systems that provide process heat.
Comparison of advanced thermal and electrical storage for parabolic dish solar thermal power systems
NASA Astrophysics Data System (ADS)
Fujita, T.; Birur, G. C.; Schredder, J. M.; Bowyer, J. M.; Awaya, H. I.
Parabolic dish solar concentrator cluster concepts are explored, with attention given to thermal storage systems coupled to Stirling and Brayton cycle power conversion devices. Sensible heat storage involving molten salt (NaOH), liquid sodium, and solid cordierite bricks are considered for 1500 F thermal storage systems. Latent heat storage with NaF-MgF2 phase change materials are explored in terms of passive, active, and direct contact designs. Comparisons are made of the effectiveness of thermal storage relative to redox, Na-S, Zn-Cl, and Zn-Br battery storage systems. Molten lead trickling down through a phase change eutectic, the NaF-MgF2, formed the direct contact system. Heat transport in all systems is effected through Inconel pipes. Using a cost goal of 120-150 mills/kWh as the controlling parameter, sensible heat systems with molten salts transport with either Stirling or Brayton engines, or latent heat systems with Stirling engines, and latent heat-Brayton engine with direct contact were favored in the analyses. Battery storage systems, however, offered the most flexibility of applications.
Tao, Y.B.; He, Y.L.
2010-10-15
A unified two-dimensional numerical model was developed for the coupled heat transfer process in parabolic solar collector tube, which includes nature convection, forced convection, heat conduction and fluid-solid conjugate problem. The effects of Rayleigh number (Ra), tube diameter ratio and thermal conductivity of the tube wall on the heat transfer and fluid flow performance were numerically analyzed. The distributions of flow field, temperature field, local Nu and local temperature gradient were examined. The results show that when Ra is larger than 10{sup 5}, the effects of nature convection must be taken into account. With the increase of tube diameter ratio, the Nusselt number in inner tube (Nu{sub 1}) increases and the Nusselt number in annuli space (Nu{sub 2}) decreases. With the increase of tube wall thermal conductivity, Nu{sub 1} decreases and Nu{sub 2} increases. When thermal conductivity is larger than 200 W/(m K), it would have little effects on Nu and average temperatures. Due to the effect of the nature convection, along the circumferential direction (from top to down), the temperature in the cross-section decreases and the temperature gradient on inner tube surface increases at first. Then, the temperature and temperature gradients would present a converse variation at {theta} near {pi}. The local Nu on inner tube outer surface increases along circumferential direction until it reaches a maximum value then it decreases again. (author)
Solar Cooking. What We Make. Science and Technology Education in Philippine Society.
ERIC Educational Resources Information Center
Philippines Univ., Quezon City. Inst. for Science and Mathematics Education Development.
This module is designed to help students: (1) describe a way of tapping solar energy; (2) identify the main parts of a box type solar cooker; (3) describe how each part contributes to the trapping of heat energy in the cooker; (4) cook some food in a solar cooker; and (5) recognize that food cooked in a solar cooker is safe to eat. It includes: an…
Grogan, Dylan C. P.
2013-08-15
Executive Summary This Final Report for the "Development of Molten-Salt Heat Transfer Fluid (HTF) Technology for Parabolic Trough Solar Power Plants” describes the overall project accomplishments, results and conclusions. Phase 1 analyzed the feasibility, cost and performance of a parabolic trough solar power plant with a molten salt heat transfer fluid (HTF); researched and/or developed feasible component options, detailed cost estimates and workable operating procedures; and developed hourly performance models. As a result, a molten salt plant with 6 hours of storage was shown to reduce Thermal Energy Storage (TES) cost by 43.2%, solar field cost by 14.8%, and levelized cost of energy (LCOE) by 9.8% - 14.5% relative to a similar state-of-the-art baseline plant. The LCOE savings range met the project’s Go/No Go criteria of 10% LCOE reduction. Another primary focus of Phase 1 and 2 was risk mitigation. The large risk areas associated with a molten salt parabolic trough plant were addressed in both Phases, such as; HTF freeze prevention and recovery, collector components and piping connections, and complex component interactions. Phase 2 analyzed in more detail the technical and economic feasibility of a 140 MWe,gross molten-salt CSP plant with 6 hours of TES. Phase 2 accomplishments included developing technical solutions to the above mentioned risk areas, such as freeze protection/recovery, corrosion effects of applicable molten salts, collector design improvements for molten salt, and developing plant operating strategies for maximized plant performance and freeze risk mitigation. Phase 2 accomplishments also included developing and thoroughly analyzing a molten salt, Parabolic Trough power plant performance model, in order to achieve the project cost and performance targets. The plant performance model and an extensive basic Engineering, Procurement, and Construction (EPC) quote were used to calculate a real levelized cost of energy (LCOE) of 11.50˘/kWhe , which achieved the Phase 2 Go/No Go target of less than 0.12˘/kWhe. Abengoa Solar has high confidence that the primary risk areas have been addressed in the project and a commercial plant utilizing molten salt is economically and technically feasible. The strong results from the Phase 1 and 2 research, testing, and analyses, summarized in this report, led Abengoa Solar to recommend that the project proceed to Phase 3. However, a commercially viable collector interconnection was not fully validated by the end of Phase 2, combined with the uncertainty in the federal budget, forced the DOE and Abengoa Solar to close the project. Thus the resources required to construct and operate a molten salt pilot plant will be solely supplied by Abengoa Solar.
3X compound parabolic concentrating (CPC) solar energy collector. Final technical report
Ballheim, R.W.
1980-04-25
Chamberlain engineers designed a 3X compound parabolic concentrating (CPC) collector for the subject contract. The collector is a completely housed, 105.75 x 44.75 x 10.23-inch, 240-pound unit with six each evacuated receiver assemblies, a center manifold and a one-piece glass cover. A truncated version of a CPC trough reflector system and the General Electric Company tubular evacuated receiver have been integrated with a mass producible collector design suitable for operation at 250 to 450/sup 0/F. The key criterion for optimization of the design was minimization of the cost per Btu collected annually at an operating temperature of 400/sup 0/F. The reflector is a 4.1X design truncated to a total height of 8.0 inches with a resulting actual concentration ratio of 2.6 to 1. The manifold is an insulated area housing the fluid lines which connect the six receivers in series with inlet and outlet tubes extending from one side of the collector at the center. The reflectors are polished, anodized aluminum which are shaped by the roll form process. The housing is painted, galvanized steel, and the cover glass is 3/16-inch thick tempered, low iron glass. The collector requires four slope adjustments per year for optimum effectiveness. Chamberlain produced ten 3X CPC collectors for the subject contract. Two collectors were used to evaluate assembly procedures, six were sent to the project officer in Albuquerque, New Mexico, one was sent to Argonne National Laboratory for performance testing and one remained with the Company. A manufacturing cost study was conducted to estimate limited mass production costs, explore cost reduction ideas and define tooling requirements. The final effort discussed shows the preliminary design for application of a 3X CPC solar collector system for use in the Iowa State Capitol complex.
Noble, William Stafford
"Diffusion of Innovation: Solar Oven Use in Lesotho (Africa)." Grundy, William and Roy Grundy and Technology. Shyam S. Nandwani, ed. July 12-15, 1994. pp. 240-247. 1 DIFFUSION OF INNOVATION: SOLAR OVEN USE of Innovation: Solar Oven Use in Lesotho (Africa)." Grundy, William and Roy Grundy. Advances in Solar Cooking
NASA Technical Reports Server (NTRS)
Hanseth, E. J.
1981-01-01
A high temperature solar receiver was fabricated and tested in excess of 1370 C on an 11-meter-diameter test bed concentrator at the Jet Propulsion Laboratory Parabolic Dish Test Site, Edwards, California. The 60-kilowatt thermal receiver design utilizes state-of-the-art silicon carbide honeycomb matrix panels to receive and transfer the solar energy and mullite elements for thermal buffer storage. Solar tests were conducted with indicated air exit temperatures ranging from 885 C (1625 F) to 1427 C (2600 F), mass flow rates of 75 to 105 g/sec (0.16 to 0.23 lbm/sec), and pressures up to 265 kPa absolute (38.4 psia). Estimates of efficiency are 59.7% at 1120 C (2048 F) to 80.6% at 885 C (1625 F) when aperture spillage losses are considered separately. Results are presented which demonstrate the feasibility of this innovative receiver concept for point-focusing parabolic dish applications over a wide temperature range.
NASA Astrophysics Data System (ADS)
Miao, L.; Kang, Y. P.; Li, C.; Tanemura, S.; Wan, C. L.; Iwamoto, Y.; Shen, Y.; Lin, H.
2015-06-01
A prototype practical solar-thermoelectric cogenerator composed of (1) a primary component of a pile of solar-selective absorber (SSA) slab, thermoelectric (TE) modules, and a depressed water flow tube (multichannel cooling heat sink, MCS), and (2) a parabolic trough concentrator with aperture area of 2m × 2m and east-west focal axis was constructed. Its cogeneration performance under the best climatic and solar insolation conditions in Guangzhou, China was tested. For simplicity, the evacuated glass tube to cover the primary component was eliminated from the system. Six Bi2Te3 TE modules were arranged in series, directly bonded to the rear surface of the solar absorber slab. The hot-side temperature of the TE module reached up to 152°C. The experimentally obtained instantaneous results for the solar to electrical conversion efficiency, heat exchange coefficient of the MCS, and overall system efficiency under the best environmental and solar insolation conditions were about 1.14%, 56.1%, and 49.5%, respectively. To justify these values, an equivalent thermal network diagram based on a single-temperature-node heat transfer model representing the respective system components was used to analyze the thermal transfer and losses of the system. Finally, electrical power of 18° W was generated, with 2 L/min of hot water at 37°C being produced and stored in the insulated container.
NASA Astrophysics Data System (ADS)
Feliciano-Cruz, Luisa I.
The increasing fossil fuel costs as well as the need to move in a somewhat sustainable future has led the world in a quest for exploiting the free and naturally available energy from the Sun to produce electric power, and Puerto Rico is no exception. This thesis proposes the design of a simulation model for the analysis and performance evaluation of a Solar Thermal Power Plant in Puerto Rico and suggests the use of the Compound Parabolic Concentrator as the solar collector of choice. Optical and thermal analysis of such collectors will be made using local solar radiation data for determining the viability of this proposed project in terms of the electric power produced and its cost.
NASA Astrophysics Data System (ADS)
Kaddour, A.; Benyoucef, B.
Solar energy is the source of the most promising energy and the powerful one among renewable energies. Photovoltaic electricity (statement) is obtained by direct transformation of the sunlight into electricity, by means of cells statement. Then, we study the operation of cells statement by the digital simulation with an aim of optimizing the output of the parabolic concentrator of Stirling engine type. The Greenius software makes it possible to carry out the digital simulation in 2D and 3D and to study the influence of the various parameters on the characteristic voltage under illumination of the cell. The results obtained enabled us to determine the extrinsic factors which depend on the environment and the intrinsic factors which result from the properties of materials used.
Selcuk, M. K.; Fujita, T.
1984-06-15
A simple graphical method has been developed to undertake technical design trade-off studies for individual parabolic dish modules comprising a two-axis tracking parabolic dish with a cavity receiver and power conversion assembly at the focal point. The results of these technical studies can then be used in performing the techno-economic analyses required for determining appropriate subsystem sizing. Selected graphs that characterize the performance of subsystems within the module have been arranged in the form of a nomogram that would enable an investigator to carry out several design trade-off studies. Key performance parameters encompassed in the nomogram include receiver losses, intercept factor, engine rating, and engine efficiency. Design and operation parameters such as concentrator size, receiver type (open or windowed aperture), receiver aperture size, operating temperature of the receiver and engine, engine partial load characteristics, concentrator slope error, and the type of reflector surface, are also included in the graphical solution. Cost considerations are not included. The nomogram has been used to perform trade-off studies that have provided a basis for determining requirements for a single concentrator that could perform satisfactorily with either the selected Stirling or Brayton engine. This activity is summarized to illustrate the usage of the nomogram. Additionally, modeling relations used in developing the nomogram are presented so that the nomogram can be updated to reflect any changes in the performance characteristics of projected components.
NASA Astrophysics Data System (ADS)
Miao, L.; Zhang, M.; Tanemura, S.; Tanaka, T.; Kang, Y. P.; Xu, G.
2012-06-01
We have designed a new solar thermoelectric cogeneration system consisting of an evacuated tubular solar collector (ETSC) with a parabolic trough concentrator (PTC) and thermoelectric modules (TEMs) to supply both thermal energy and electricity. The main design concepts are (1) the hot side of the TEM is bonded to the solar selective absorber installed in an evacuated glass tube, (2) the cold side of the TEM is also bonded to the heat sink, and (3) the outer circulated water is heated by residual solar energy after TEM generation. We present an example solar thermal simulation based on energy balance and heat transfer as used in solar engineering to predict the electrical conversion efficiency and solar thermal conversion efficiency for different values of parameters such as the solar insolation, concentration ratio, and TEM ZT values.
NASA Technical Reports Server (NTRS)
Dehne, Hans J.
1991-01-01
NASA has initiated technology development programs to develop advanced solar dynamic power systems and components for space applications beyond 2000. Conceptual design work that was performed is described. The main efforts were the: (1) conceptual design of self-deploying, high-performance parabolic concentrator; and (2) materials selection for a lightweight, shape-stable concentrator. The deployment concept utilizes rigid gore-shaped reflective panels. The assembled concentrator takes an annular shape with a void in the center. This deployable concentrator concept is applicable to a range of solar dynamic power systems of 25 kW sub e to in excess of 75 kW sub e. The concept allows for a family of power system sizes all using the same packaging and deployment technique. The primary structural material selected for the concentrator is a polyethyl ethylketone/carbon fiber composite also referred to as APC-2 or Vitrex. This composite has a nearly neutral coefficient of thermal expansion which leads to shape stable characteristics under thermal gradient conditions. Substantial efforts were undertaken to produce a highly specular surface on the composite. The overall coefficient of thermal expansion of the composite laminate is near zero, but thermally induced stresses due to micro-movement of the fibers and matrix in relation to each other cause the surface to become nonspecular.
Commercialization of parabolic dish systems
NASA Astrophysics Data System (ADS)
Washom, B.
1982-07-01
The impact of recent federal tax and regulatory legislation on the commercialization of parabolic solar reflector technology is assessed. Specific areas in need of technical or economic improvement are noted.
Commercialization of parabolic dish systems
NASA Technical Reports Server (NTRS)
Washom, B.
1982-01-01
The impact of recent federal tax and regulatory legislation on the commercialization of parabolic solar reflector technology is assessed. Specific areas in need of technical or economic improvement are noted.
Mechanical development of an actuation system for a parabolic solar trough collector
Carrillo, Juan Felipe (Carrillo Salazar)
2013-01-01
This thesis documents my personal contribution to the development of a hydraulic-based actuation system for a solar trough collector. The goal of this project was to design the actuation system using hydraulic actuators ...
Design and analysis of hydraulically driven actuation system For a parabolic solar trough
Popovi?, Katarina, S.B. Massachusetts Institute of Technology
2013-01-01
This thesis documents Katarina Popovic's contribution to the design of hydraulic cylinder actuation system for day to day solar trough sun tracking, a semester long project within 2.752 Development of Mechanical Products ...
Testing Parabolic-Dish Concentrators
NASA Technical Reports Server (NTRS)
Selcuk, M. Kudret
1988-01-01
Report describes test equipment and tests at Parabolic Dish Test Site at Edwards Air Force Base in California. Site established in 1978 for testing point-focusing solar concentrators operating at temperatures above 600 degree F. Used for six years to evaluate parabolic-dish concentrators, receivers, power-conversion units, and solar/fossil-fuel hybrid units. Report describes evolution of test program at site, lists experiments conducted there in chronological order, and summarizes experimental data.
Mehos, M. S.; Wagner, M. J.; Kearney, D. W.
2011-08-01
Prior to commercial operation, large solar systems in utility-size power plants need to pass a performance acceptance test conducted by the engineering, procurement, and construction (EPC) contractor or owners. In lieu of the present absence of ASME or other international test codes developed for this purpose, the National Renewable Energy Laboratory has undertaken the development of interim guidelines to provide recommendations for test procedures that can yield results of a high level of accuracy consistent with good engineering knowledge and practice. Progress on interim guidelines was presented at SolarPACES 2010. Significant additions and modifications were made to the guidelines since that time, resulting in a final report published by NREL in April 2011. This paper summarizes those changes, which emphasize criteria for assuring thermal equilibrium and steady state conditions within the solar field.
Fontán-Sainz, María; Gómez-Couso, Hipólito; Fernández-Ibáńez, Pilar; Ares-Mazás, Elvira
2012-01-01
Water samples of 0, 5, and 30 nephelometric turbidity units (NTU) spiked with Cryptosporidium parvum oocysts were exposed to natural sunlight using a 25-L static solar reactor fitted with a compound parabolic collector (CPC). The global oocyst viability was calculated by the evaluation of the inclusion/exclusion of the fluorogenic vital dye propidium iodide and the spontaneous excystation. After an exposure time of 8 hours, the global oocyst viabilities were 21.8 ± 3.1%, 31.3 ± 12.9%, and 45.0 ± 10.0% for turbidity levels of 0, 5, and 30 NTU, respectively, and these values were significantly lower (P < 0.05) that the initial global viability of the isolate (92.1 ± 0.9%). The 25-L static solar reactor that was evaluated can be an alternative system to the conventional solar water disinfection process for improving the microbiological quality of drinking water on a household level, and moreover, it enables treatment of larger volumes of water (> 10 times). PMID:22302852
Heath, G. A.; Burkhardt, J. J.; Turchi, C. S.
2011-09-01
Climate change and water scarcity are important issues for today's power sector. To inform capacity expansion decisions, hybrid life cycle assessment is used to evaluate a reference design of a parabolic trough concentrating solar power (CSP) facility located in Daggett, California, along four sustainability metrics: life cycle greenhouse gas (GHG) emissions, water consumption, cumulative energy demand (CED), and energy payback time (EPBT). This wet-cooled, 103 MW plant utilizes mined nitrate salts in its two-tank, thermal energy storage (TES) system. Design alternatives of dry-cooling, a thermocline TES, and synthetically-derived nitrate salt are evaluated. During its life cycle, the reference CSP plant is estimated to emit 26 g CO2eq per kWh, consume 4.7 L/kWh of water, and demand 0.40 MJeq/kWh of energy, resulting in an EPBT of approximately 1 year. The dry-cooled alternative is estimated to reduce life cycle water consumption by 77% but increase life cycle GHG emissions and CED by 8%. Synthetic nitrate salts may increase life cycle GHG emissions by 52% compared to mined. Switching from two-tank to thermocline TES configuration reduces life cycle GHG emissions, most significantly for plants using synthetically-derived nitrate salts. CSP can significantly reduce GHG emissions compared to fossil-fueled generation; however, dry-cooling may be required in many locations to minimize water consumption.
Burkhardt, John J; Heath, Garvin A; Turchi, Craig S
2011-03-15
Climate change and water scarcity are important issues for today's power sector. To inform capacity expansion decisions, hybrid life cycle assessment is used to evaluate a reference design of a parabolic trough concentrating solar power (CSP) facility located in Daggett, CA, along four sustainability metrics: life cycle (LC) greenhouse gas (GHG) emissions, water consumption, cumulative energy demand (CED), and energy payback time (EPBT). This wet-cooled, 103 MW plant utilizes mined nitrates salts in its two-tank, thermal energy storage (TES) system. Design alternatives of dry-cooling, a thermocline TES, and synthetically derived nitrate salt are evaluated. During its LC, the reference CSP plant is estimated to emit 26 g of CO(2eq) per kWh, consume 4.7 L/kWh of water, and demand 0.40 MJ(eq)/kWh of energy, resulting in an EPBT of approximately 1 year. The dry-cooled alternative is estimated to reduce LC water consumption by 77% but increase LC GHG emissions and CED by 8%. Synthetic nitrate salts may increase LC GHG emissions by 52% compared to mined. Switching from two-tank to thermocline TES configuration reduces LC GHG emissions, most significantly for plants using synthetically derived nitrate salts. CSP can significantly reduce GHG emissions compared to fossil-fueled generation; however, dry-cooling may be required in many locations to minimize water consumption. PMID:21391722
International Experience in Standards and Labeling Programs for Rice Cookers
Zhou, Nan; Zheng, Nina
2008-05-01
China has had an active program on energy efficiency standards for household appliances since the mid-1990s. Rice cooker is among the first to be subject to such mandatory regulation, since it is one of the most prevalent electric appliances in Chinese households. Since first introduced in 1989, the minimum energy efficiency standard for rice cookers has not been revised. Therefore, the potential for energy saving is considerable. Initial analysis from CNIS indicates that potential carbon savings is likely to reach 7.6 million tons of CO2 by the 10th year of the standard implementation. Since September 2007, CNIS has been working with various groups to develop the new standard for rice cookers. With The Energy Foundation's support, LBNL has assisted CNIS in the revision of the minimum energy efficiency standard for rice cookers that is expected to be effective in 2009. Specifically, work has been in the following areas: assistance in developing consumer survey on usage pattern of rice cookers, review of international standards, review of international test procedures, comparison of the international standards and test procedures, and assessment of technical options of reducing energy use. This report particularly summarizes the findings of reviewing international standards and technical options of reducing energy consumption. The report consists of an overview of rice cooker standards and labeling programs and testing procedures in Hong Kong, South Korea, Japan and Thailand, and Japan's case study in developing energy efficiency rice cooker technologies and rice cooker efficiency programs. The results from the analysis can be summarized as the follows: Hong Kong has a Voluntary Energy Efficiency Labeling scheme for electric rice cookers initiated in 2001, with revision implemented in 2007; South Korea has both MEPS and Mandatory Energy Efficiency Label targeting the same category of rice cookers as Hong Kong; Thailand's voluntary endorsement labeling program is similar to Hong Kong in program design but has 5 efficiency grades; Japan's program is distinct in its adoption of the 'Top Runner' approach, in which, the future efficiency standards is set based on the efficiency levels of the most efficient product in the current domestic market. Although the standards are voluntary, penalties can still be evoked if the average efficiency target is not met. Both Hong Kong and South Korea's tests involve pouring water into the inner pot equal to 80% of its rated volume; however, white rice is used as a load for its tests in Hong Kong whereas no rice is used for tests in South Korea. In Japan's case, water level specified by the manufactures is used and milled rice is used as a load only partially in the tests. Moreover, Japan does not conduct heat efficiency test but its energy consumption measurements tests are much more complex, with 4 different tests are conducted to determine the annual average energy consumption. Hong Kong and Thailand both set Minimum Allowable Heat Efficiency for different rated wattages. The energy efficiency requirements are identical except that the minimum heat efficiency in Thailand is 1 percentage point higher for all rated power categories. In South Korea, MEPS and label's energy efficiency grades are determined by the rice cooker's Rated Energy Efficiency for induction, non-induction, pressure, nonpressure rice cookers. Japan's target standard values are set for electromagnetic induction heating products and non-electromagnetic induction heating products by different size of rice cookers. Specific formulas are used by type and size depending on the mass of water evaporation of the rice cookers. Japan has been the leading country in technology development of various types of rice cookers, and developed concrete energy efficiency standards for rice cookers. However, as consumers in Japan emphasize the deliciousness of cooked rice over other factors, many types of models were developed to improve the taste of cooked rice. Nonetheless, the efficiency of electromagnetic induction heating (IH) rice cook
Solar cooking experiments with different foods
Devadas, R.P.; Jagadeesan, G.
1992-12-31
This paper describes studies with a variety of solar cookers at Avinashilingam Deemed University, India. The objective of the studies was to determine the following: the time needed for cooking various foods; the amount of fuel conserved; and suitable menus for use with the cooker. It was concluded that, on bright sunny days, the solar cooker can be used satisfactorily for preparing cereals, legumes, vegetables, roots and tubers, bakery items, eggs and groundnuts. Inadequate and intermittent sunshine, fluctuation in wind velocity, clouds, rain and other environmental factors could affect the solar intensity which, in turn, would affect the cooking time. The palatability of solar cooked items was satisfactory when compared to items cooked using firewood, kerosene or gas. Among the various solar cooking devices, the box type cookers were found to have advantages over the basket type due to convenience in handling. However, it is not possible to prepare certain items commonly used in India using the box type cookers.
Comparison of advanced engines for parabolic dish solar thermal power plants
NASA Technical Reports Server (NTRS)
Fujita, T.; Bowyer, J. M.; Gajanana, B. C.
1980-01-01
A paraboloidal dish solar thermal power plant produces electrical energy by a two-step conversion process. The collector subsystem is composed of a two-axis tracking paraboloidal concentrator and a cavity receiver. The concentrator focuses intercepted sunlight (direct, normal insolation) into a cavity receiver whose aperture encircles the focal point of the concentrator. At the internal wall of the receiver the electromagnetic radiation is converted to thermal energy. A heat engine/generator assembly then converts the thermal energy captured by the receiver to electricity. Developmental activity has been concentrated on small power modules which employ 11- to 12-meter diameter dishes to generate nominal power levels of approximately 20 kWe. A comparison of advanced heat engines for the dish power module is presented in terms of the performance potential of each engine with its requirements for advanced technology development. Three advanced engine possibilities are the Brayton (gas turbine), Brayton/Rankine combined cycle, and Stirling engines.
Ma, R.Y.
1993-09-01
Tests were performed to determine the convective heat loss characteristics of a cavity receiver for a parabolid dish concentrating solar collector for various tilt angles and wind speeds of 0-24 mph. Natural (no wind) convective heat loss from the receiver is the highest for a horizontal receiver orientation and negligible with the reveler facing straight down. Convection from the receiver is substantially increased by the presence of side-on wind for all receiver tilt angles. For head-on wind, convective heat loss with the receiver facing straight down is approximately the same as that for side-on wind. Overall it was found that for wind speeds of 20--24 mph, convective heat loss from the receiver can be as much as three times that occurring without wind.
Muir, J.F.; Hogan, R.E. Jr.; Skocypec, R.D.; Buck, R.
1993-07-01
A joint US/Federal Republic of Germany (FRG) project has successfully tested a unique solar-driven chemical reactor in the CAtalytically Enhanced Solar Absorption Receiver (CAESAR) experiment. The CAESAR test was a {open_quotes}proof-of-concept{close_quotes} demonstration of carbon-dioxide reforming of methane in a commercial-scale, solar, volumetric receiver/reactor on a parabolic dish concentrator. The CAESAR design; test facility and instrumentation; thermal and chemical tests; and analysis of test results are presented in detail. Numerical models for the absorber and the receiver are developed and predicted performance is compared with test data. Post test analyses to assess the structural condition of the absorber and the effectiveness of the rhodium catalyst are presented. Unresolved technical issues are identified and future development efforts are recommended.
NASA Technical Reports Server (NTRS)
1981-01-01
The manufacturing cost of a General Electric 12 meter diameter concentrator was estimated. This parabolic dish concentrator for solar thermal system was costed in annual production volumes of 100 - 1,000 - 5,000 - 10,000 - 50,000 100,000 - 400,000 and 1,000,000 units. Presented for each volume are the costs of direct labor, material, burden, tooling, capital equipment and buildings. Also presented is the direct labor personnel and factory space requirements. All costs are based on early 1981 economics.
Parabolic dish module experiment
NASA Astrophysics Data System (ADS)
1986-03-01
A development test model of the 8-meter Solar Brayton Parabolic Dish Module has been designed, fabricated, and tested. The test model consists of five major subsystems: Sanders ceramic honeycomb solar receiver; LaJet LEC460 solar concentrator; AiRsearch SABC MKIIIA engine, Abacus 8 kW ac inverter; and a Sanders designed and built system controller. Goals of the tests were to integrate subsystem components into a working module, demonstrate the concept, and generate 5 kWe (hybrid) and 4.7 kWe (solar only) input. All subsystem integration goals were successfully achieved, but system performance efficiency was lower than expected. Contributing causes of the lower performance efficiencies have been identified. Modifications needed to restore performance to the required levels and improve the system life cycle cost have been addressed and are the subject of this final report.
NASA Technical Reports Server (NTRS)
Selcuk, M. K.; Fujita, T.
1984-01-01
A simple graphical method was developed to undertake technical design trade-off studies for individual parabolic dish models comprising a two-axis tracking parabolic dish with a cavity receiver and power conversion assembly at the focal point. The results of these technical studies are then used in performing the techno-economic analyses required for determining appropriate subsystem sizing. Selected graphs that characterize the performance of subsystems within the module were arranged in the form of a nomogram that would enable an investigator to carry out several design trade-off studies. Key performance parameters encompassed in the nomogram include receiver losses, intercept factor, engine rating, and engine efficiency. Design and operation parameters such as concentrator size, receiver type (open or windowed aperture), receiver aperture size, operating temperature of the receiver and engine, engine partial load characteristics, concentrator slope error, and the type of reflector surface, are also included in the graphical solution. Cost considerations are not included.
NASA Technical Reports Server (NTRS)
Jaffe, Leonard D.
1988-01-01
This paper presents results of development testing of various solar thermal parabolic dish modules and assemblies. Most of the tests were at modules and assemblies that used a dish-mounted, organic Rankine cycle turbine for production of electric power. Some tests were also run on equipment for production of process steam or for production of electricity using dish-mounted reciprocating steam engines. These tests indicate that early modules achieve efficiencies of about 18 percent in converting sunlight to electricity (excluding the inverter but including parasitics). A number of malfunctions occurred. The performance measurements, as well as the malfunctions and other operating experience, provided information that should be of value in developing systems with improved performance and reduced maintenance.
Colina-Márquez, José; Machuca-Martínez, Fiderman; Li Puma, Gianluca
2015-01-01
Endocrine disruptors in water are contaminants of emerging concern due to the potential risks they pose to the environment and to the aquatic ecosystems. In this study, a solar photocatalytic treatment process in a pilot-scale compound parabolic collector (CPC) was used to remove commercial estradiol formulations (17-? estradiol and nomegestrol acetate) from water. Photolysis alone degraded up to 50% of estradiol and removed 11% of the total organic carbon (TOC). In contrast, solar photocatalysis degraded up to 57% of estrogens and the TOC removal was 31%, with 0.6 g/L of catalyst load (TiO2 Aeroxide P-25) and 213.6 ppm of TOC as initial concentration of the commercial estradiols formulation. The adsorption of estrogens over the catalyst was insignificant and was modeled by the Langmuir isotherm. The TOC removal via photocatalysis in the photoreactor was modeled considering the reactor fluid-dynamics, the radiation field, the estrogens mass balance, and a modified Langmuir-Hinshelwood rate law, that was expressed in terms of the rate of photon adsorption. The optimum removal of the estrogens and TOC was achieved at a catalyst concentration of 0.4 g/L in 29 mm diameter tubular CPC reactors which approached the optimum catalyst concentration and optical thickness determined from the modeling of the absorption of solar radiation in the CPC, by the six-flux absorption-scattering model (SFM). PMID:26205059
The pressure cooker technique for the treatment of brain AVMs.
Chapot, René; Stracke, Paul; Velasco, Aglaé; Nordmeyer, Hannes; Heddier, Markus; Stauder, Michael; Schooss, Petra; Mosimann, Pascal J
2014-03-01
Arteriovenous malformations (AVMs) may be cured by injecting liquid embolic agents such as Onyx. Reflux, however, can sometimes be difficult to control and may jeopardize a complete embolization. The pressure cooker technique (PCT) was designed to create an anti-reflux plug by trapping the detachable part of an Onyx-compatible microcatheter with coils and glue in order to obtain wedge-flow conditions, thereby enabling a better understanding of macrofistulous AVMs and a more comprehensive, forceful and controlled Onyx embolization. The PCT might enlarge the range of AVMs amenable to endovascular cure. Three illustrative cases are presented. PMID:24405685
Isarain-Chávez, Eloy; Rodríguez, Rosa María; Cabot, Pere Lluís; Centellas, Francesc; Arias, Conchita; Garrido, José Antonio; Brillas, Enric
2011-08-01
The degradation of the beta-blockers atenolol, metoprolol tartrate and propranolol hydrochloride was studied by electro-Fenton (EF) and solar photoelectro-Fenton (SPEF). Solutions of 10 L of 100 mg L?ą of total organic carbon of each drug in 0.1 M Na?SO? with 0.5 mM Fe˛? of pH 3.0 were treated in a recirculation flow plant with an electrochemical reactor coupled with a solar compound parabolic collector. Single Pt/carbon felt (CF) and boron-doped diamond (BDD)/air-diffusion electrode (ADE) cells and combined Pt/ADE-Pt/CF and BDD/ADE-Pt/CF cells were used. SPEF treatments were more potent with the latter cell, yielding 95-97% mineralization with 100% of maximum current efficiency and energy consumptions of about 0.250 kWh g TOC?ą. However, the Pt/ADE-Pt/CF cell gave much lower energy consumptions of about 0.080 kWh g TOC?ą with slightly lower mineralization of 88-93%, then being more useful for its possible application at industrial level. The EF method led to a poorer mineralization and was more potent using the combined cells by the additional production of hydroxyl radicals (•OH) from Fenton's reaction from the fast Fe˛? regeneration at the CF cathode. Organics were also more rapidly destroyed at BDD than at Pt anode. The decay kinetics of beta-blockers always followed a pseudo first-order reaction, although in SPEF, it was accelerated by the additional production of •OH from the action of UV light of solar irradiation. Aromatic intermediates were also destroyed by hydroxyl radicals. Ultimate carboxylic acids like oxalic and oxamic remained in the treated solutions by EF, but their Fe(III) complexes were photolyzed by solar irradiation in SPEF, thus explaining its higher oxidation power. NO?? was the predominant inorganic ion lost in EF, whereas the SPEF process favored the production of NH?? ion and volatile N-derivatives. PMID:21693380
Optimal Heat Collection Element Shapes for Parabolic Trough Concentrators
Bennett, C
2007-11-15
For nearly 150 years, the cross section of the heat collection tubes used at the focus of parabolic trough solar concentrators has been circular. This type of tube is obviously simple and easily fabricated, but it is not optimal. It is shown in this article that the optimal shape, assuming a perfect parabolic figure for the concentrating mirror, is instead oblong, and is approximately given by a pair of facing parabolic segments.
Not Available
1982-11-30
The major activities reported are: a market study to identify an early market for a dish-Stirling module and assess its commercial potential; preparation of a conceptual system and subsystem design to address this market; and preparation of an early sales implementation plan. A study of the reliability of protection from the effects of walk-off, wherein the sun's image leaves the receiver if the dish is not tracking, is appended, along with an optical analysis and structural analysis. Also appended are the relationship between PURPA and solar thermal energy development and electric utility pricing rationale. (LEW)
Parabolic Dish Stirling Module
NASA Technical Reports Server (NTRS)
Washom, B.
1984-01-01
The design, manufacture, and assembly of a commercially designed parabolic dish Stirling 25 kWe module is examined. The cost, expected performance, design uniquenesses, and future commercial potential of this module, which is regarded as the most technically advanced in the parabolic dish industry is discussed.
The French thermo-helio-electricity-KW parabolic dish program
NASA Technical Reports Server (NTRS)
Audibert, M.; Peri, G.
1982-01-01
The testing and development of parabolic dish solar thermal power plants to produce, thermal mechanical, or electrical energy are discussed. The design, construction, and experiments of prototype collectors to prove the feasibility of such collectors is described.
Parabolic dish test site: History and operating experience
NASA Technical Reports Server (NTRS)
Selcuk, M. K. (compiler)
1985-01-01
The parabolic dish test site (PDTS) was established for testing point-focusing solar concentrator systems operating at temperatures approaching 1650 C. Among tests run were evaluation and performance characterization of parabolic dish concentrators, receivers, power conversion units, and solar/fossil-fuel hybrid systems. The PDTS was fully operational until its closure in June, 1984. The evolution of the test program, a chronological listing of the experiments run, and data summaries for most of the tests conducted are presented.
Parabolic Dish Concentrator (PDC-1)
NASA Technical Reports Server (NTRS)
Dennison, E. W.; Argoud, M. J.
1984-01-01
The design, construction, and installation of the Parabolic Dish Concentrator, Type 1 (PDC-1) has been one of the most significant JPL concentrator projects because of the knowledge gained about this type of concentrator and the development of design, testing, and analysis procedures which are applicable to all solar concentrator projects. The need for these procedures was more clearly understood during the testing period which started with the prototype panel evaluation and ended with the performance characterization of the completed concentrator. For each phase of the test program, practical test procedures were required and these procedures defined the mathematical analysis which was essential for successful concentrator development. The concentrator performance appears to be limited only by the distortions resulting from thermal gradients through the reflecting panels. Simple optical testing can be extremely effective, but comprehensive mechanical and optical analysis is essential for cost effective solar concentrator development.
Microphotonic parabolic light directors fabricated by two-photon lithography
NASA Astrophysics Data System (ADS)
Atwater, J. H.; Spinelli, P.; Kosten, E.; Parsons, J.; Van Lare, C.; Van de Groep, J.; Garcia de Abajo, J.; Polman, A.; Atwater, H. A.
2011-10-01
We have fabricated microphotonic parabolic light directors using two-photon lithography, thin-film processing, and aperture formation by focused ion beam lithography. Optical transmission measurements through upright parabolic directors 22 ?m high and 10 ?m in diameter exhibit strong beam directivity with a beam divergence of 5.6°, in reasonable agreement with ray-tracing and full-field electromagnetic simulations. The results indicate the suitability of microphotonic parabolic light directors for producing collimated beams for applications in advanced solar cell and light-emitting diode designs.
The Pressure Cooker: A Module on the Properties of Matter. Tech Physics Series.
ERIC Educational Resources Information Center
Technical Education Research Center, Cambridge, MA.
Experiments to provide an understanding of the principles related to the pressure cooker are presented. Objectives included are designed to provide the learner with the ability to calibrate a thermistor for measuring temperature; explain the meaning of latent and specific heat; calculate latent and specific heat; use a Bourdon tube pressure gauge…
Understanding the Clausius-Clapeyron Equation by Employing an Easily Adaptable Pressure Cooker
ERIC Educational Resources Information Center
Galleano, Monica; Boveris, Alberto; Puntarulo, Susana
2008-01-01
This article describes a simple and inexpensive laboratory exercise developed to understand the effect of pressure on phase equilibrium as described by the Clausius-Clapeyron equation. The only piece of equipment required is a pressure cooker adapted with a pressure gauge and a thermometer in the lid, allowing the measurement of the pressure and…
Session: Parabolic Troughs (Presentation)
Kutscher, C.
2008-04-01
The project description is R and D activities at NREL and Sandia aimed at lowering the delivered energy cost of parabolic trough collector systems and FOA awards to support industry in trought development. The primary objectives are: (1) support development of near-term parabolic trought technology for central station power generation; (2) support development of next-generation trought fields; and (3) support expansion of US trough industry. The major FY08 activities were: (1) improving reflector optics; (2) reducing receiver heat loss (including improved receiver coating and mitigating hydrogen accumulation); (3) measuring collector optical efficiency; (4) optimizing plant performance and reducing cost; (5) reducing plant water consumption; and (6) directly supporting industry needs, including FOA support.
Numerical modeling and experimental testing of a solar grill
Olwi, I.; Khalifa, A. )
1993-02-01
The sun provides a free, nonpolluting and everlasting source of energy. Considerable research has been carried out to utilize solar energy for purposes such as water heating, high temperature ovens, and conversion to electrical energy. One of the interesting forms for utilizing solar energy is cooking. The main disadvantage of solar energy systems has been the low efficiency attained in most of its practical applications. It is expected, however, that due to continuing decreases in the availability of other energy sources such as oil and coal, along with the safety problems associated with nuclear energy, man's need for utilization of solar energy will increase, thus leading him to find the ways and means to develop adequate and efficient solar-powered systems. In camps, where tents are used to accommodate people, cooking is done via conventional gas stoves. This usually takes place in extremely crowded areas which become highly fireprone. Solar oven cookers seem to be a viable alternative considering both economy and safety. Among the various forms of solar cookers, the oven-type solar cooker is known to be the best in terms of efficiency. One of the most practical and efficient forms of solar oven cookers is the outdoor portable solar grill (Bar-B-Q), developed by Khalifa et al. The solar grill is a light and portable unit that utilizes solar energy to grill meat. One of the best types of grilling with this cooker is the well-known Shish Kebab or Bar-B-Q. A detailed description for the design of the solar grill is provided as follows. This paper is aimed at providing experimental results and formulating a numerical model for the solar grill. Results of the two approaches are then compared to verify the validity of the numerical simulation. An experimental and theoretical investigation was conducted on the solar grill in order to study the factors that affect its design and performance.
Solar Energy Education. Home economics: student activities. Field test edition
Not Available
1981-03-01
A view of solar energy from the standpoint of home economics is taken in this book of activities. Students are provided information on solar energy resources while performing these classroom activities. Instructions for the construction of a solar food dryer and a solar cooker are provided. Topics for study include window treatments, clothing, the history of solar energy, vitamins from the sun, and how to choose the correct solar home. (BCS)
Gawlik, K.
2010-08-01
Tested parabolic trough products provided by SkyFuel, a manufacturer of parabolic trough systems in the concentrating solar thermal power industry. The testing evaluated the performance of the system at the Optical Efficiency Test Loop at Solar Industrial Mesa Top Area.
Ndounla, J; Pulgarin, C
2015-11-01
The photo-disinfection of natural alkaline surface water (pH 8.6?±?0.3) for drinking purposes was carried out under solar radiation treatments. The enteric bacteria studied were the wild total coliforms/Escherichia coli (10(4) CFU/ml) and Salmonella spp. (10(4) CFU/ml) naturally present in the water. The photo-disinfection of a 25-l water sample was carried out in a solar compound parabolic collector (CPC) in the absence and in the presence of hydrogen peroxide (H2O2). The addition of H2O2 (10 mg/L) to the sample water was sufficient to enhance the photo-disinfection and ensure an irreversible lethal action on the wild enteric bacteria contents of the sample. The inactivation kinetic of the system was significantly enhanced compared to the one carried out without H2O2 addition. The effect of the solar radiation parameters on the efficiency of the photo-disinfection were assessed. The pH has increased during the treatment in all the photo-disinfection processes (hv and H2O2/hv). The Salmonella spp strain has shown the best effective inactivate time in alkaline water than the one recorded under acidic or near-neutral conditions. The evolution of some physico-chemical parameters of the water (turbidity, NO2 (-), NO3 (-), NH4 (+), HPO4 (2-), and bicarbonate (HCO3 (-))) was monitored during the treatment. Finally, the possible mechanistic process involved during the enteric bacteria inactivation was suggested. PMID:26122565
TITS SYSTEMS, PARABOLIC SUBGROUPS, PARABOLIC SUBALGEBRAS Alfred G. Noel
NoĂ«l, Alfred G.
TITS SYSTEMS, PARABOLIC SUBGROUPS, PARABOLIC SUBALGEBRAS Alfred G. NoÂ¨el Department of Mathematics worked over an arbitrary field. In a 1962 paper, Tits gave an axiomatic treatment of Chevalley's work group. In his work on Buildings Tits explained how a group with a BN- pair gave rise to a geometry
TITS SYSTEMS, PARABOLIC SUBGROUPS, PARABOLIC SUBALGEBRAS Alfred G. Noel
NoĂ«l, Alfred G.
TITS SYSTEMS, PARABOLIC SUBGROUPS, PARABOLIC SUBALGEBRAS Alfred G. NoË?el Department of Mathematics. Moreover he worked over an arbitrary field. In a 1962 paper, Tits gave an axiomatic treatment of Chevalley a Coxeter group. In his work on Buildings Tits explained how a group with a BNÂ pair gave rise to a geometry
Lu, Lu; Zhao, Luping; Zhang, Caimeng; Kong, Xiangzhen; Hua, Yufei; Chen, Yeming
2015-03-01
During thermal treatment of soymilk, a rapid incorporation of Kunitz trypsin inhibitor (KTI) into protein aggregates by covalent (disulfide bond, SS) and/or noncovalent interactions with other proteins is responsible for its fast inactivation of trypsin inhibitor activity (TIA). In contrast, the slow cleavage of a single Bowman-Birk inhibitor (BBI) peptide bond is responsible for its slow inactivation of TIA and chymotrypsin inhibitor activity (CIA). In this study, the effects of Ohmic heating (220 V, 50 Hz) on soymilk TIA and CIA inactivation were examined and compared to induction cooker and electric stove heating with similar thermal histories. It was found that: (1) TIA and CIA inactivation was slower from 0 to 3 min, and faster after 3 min as compared to induction cooker and electric stove. (2) The thiol (SH) loss rate was slower from 0 to 3 min, and similar to induction cooker and electric stove after 3 min. (3) Ohmic heating slightly increased protein aggregate formation. (4) In addition to the cleavage of one BBI peptide bond, an additional reaction might occur to enhance BBI inactivation. (5) Ohmic heating was more energy-efficient for TIA and CIA inactivation. (6) TIA and CIA inactivation was accelerated with increasing electric voltage (110, 165, and 220 V) of Ohmic heating. It is likely that the enhanced inactivation of TIA by Ohmic heating is due to its combined electrochemical and thermal effects. PMID:25678063
Kim, Seung-Hyun; Yu, Bo-Ra; Chung, Ill-Min
2015-06-01
This study investigated the changes in the contents and profiles of 35 phenolics (including 12 isoflavones), four tocopherols, two soyasapogenols and 20 amino acids when soybean and rice were cooked together (soybean-rice mixture) using either an electric rice cooker (ERC) or an electric pressure rice cooker (EPRC). The contents of the 35 selected phenolics in soybean decreased by 12% and 8% upon cooking by ERC and EPRC, respectively, and their profiles were different from that prior to cooking (P<0.05). Total tocopherol content of soybeans decreased by 7% after cooking in an ERC, but increased by 3% in soybeans cooked by EPRC. Total soyasapogenol content in soybeans cooked by ERC and EPRC decreased by 15% and 6%, respectively. Lastly, the total amino acid content of soybeans increased by 41% and 10% after cooking by ERC and EPRC, respectively. This study extends our knowledge about the effects of heat and pressure on the contents and profiles of bioactive compounds during soybean-rice mixture cooking. These results may be useful for improving the quality of bioactive compounds in soybean and rice depending on cooking conditions. PMID:25624205
A successful solar cooking introduction model
Lankford, W.F.
1992-12-31
The author reviews the process he has undertaken to introduce solar cooking in Central America. A slow but increasingly successful acceptance rate is attributed to the following factors: the adaptation of the physical design of the cooker to local conditions; the determination of essential accessories for successful cooking; preliminary assessment of the probability for successful solar cooking; the structure of the oven building workshops; the follow-up program for those who have built their solar ovens. The follow-up program is the emphasis of his current research. The program can be divided into two categories. One is physical maintenance, repair and upgrade needs. The second is education in solar cooking. Another is orientation in the physical use of the oven. While these measures are expected to increase utilization, subsidies will be needed if solar cookers are expected to compete with highly subsidized fuel alternatives such as natural gas and electricity.
Solar thermal technology evaluation, fiscal year 1982. Volume 1: Executive summary
NASA Technical Reports Server (NTRS)
1983-01-01
Three primary solar concepts the central receiver, parabolic dish, and parabolic trough are investigated. To a lesser extent, the hemispherical bowl and salt-gradient solar pond are also being studied. Each technology is described.
Solar thermal technology evaluation, fiscal year 1982. Volume 1: Executive summary
NASA Astrophysics Data System (ADS)
1983-07-01
Three primary solar concepts the central receiver, parabolic dish, and parabolic trough are investigated. To a lesser extent, the hemispherical bowl and salt-gradient solar pond are also being studied. Each technology is described.
Pre- and post-natal exposure of children to EMF generated by domestic induction cookers
NASA Astrophysics Data System (ADS)
Kos, Bor; Vali?, Blaž; Miklav?i?, Damijan; Kotnik, Tadej; Gajšek, Peter
2011-10-01
Induction cookers are a type of cooking appliance that uses an intermediate-frequency magnetic field to heat the cooking vessel. The magnetic flux density produced by an induction cooker during operation was measured according to the EN 62233 standard, and the measured values were below the limits set in the standard. The measurements were used to validate a numerical model consisting of three vertically displaced coaxial current loops at 35 kHz. The numerical model was then used to compute the electric field (E) and induced current (J) in 26 and 30 weeks pregnant women and 6 and 11 year old children. Both E and J were found to be below the basic restrictions of the 2010 low-frequency and 1998 ICNRIP guidelines. The maximum computed E fields in the whole body were 0.11 and 0.66 V m-1 in the 26 and 30 weeks pregnant women and 0.28 and 2.28 V m-1 in the 6 and 11 year old children (ICNIRP basic restriction 4.25 V m-1). The maximum computed J fields in the whole body were 46 and 42 mA m-2 in the 26 and 30 weeks pregnant women and 27 and 16 mA m-2 in the 6 and 11 year old children (ICNIRP basic restriction 70 mA m-2).
Technology Transfer Automated Retrieval System (TEKTRAN)
Koshihikari and Basmati rices, two premium rices from Japan and Pakistan respectively, were evaluated for volatile compounds and textural characteristics using three different cooking methods. Three hundred grams of each rice were prepared in National and Hitachi rice cookers and a covered saucepan...
Configuration selection study for isolated loads using parabolic dish modules
NASA Technical Reports Server (NTRS)
Revere, W.; Bowyer, J.; Fujita, T.; Awaya, H.
1982-01-01
A configuration tradeoff study was conducted to determine optimum solar thermal parabolic dish power systems for isolated load applications. The specific application of an essentially constant power demand as required for MX missile shelters is treated. Supplying a continuous level of power with high reliability is shown to require a power system comprising modular parabolic dish power units where the heat engines of the modular power units can be driven by fossil fuels as well as solar-derived heat. Since constraints on reliability result in the provision of a power generating capability that exceeds the constant demand level, efficient utilization of the power system requires battery storage. Tradeoffs regarding the optimum size of storage are investigated as a function of the number of power modules and the cost of the fossil fuel.
Configuration selection study for isolated loads using parabolic dish modules
NASA Technical Reports Server (NTRS)
Revere, W.; Bowyer, J.; Fujita, T.; Awaya, H.
1981-01-01
A configuration tradeoff study has been conducted to determine optimum solar thermal parabolic dish power systems for isolated load applications. The specific application of an essentially constant power demand as required for MX missile shelters is treated. Supplying a continuous level of power with high reliability is shown to require a power system comprising modular parabolic dish power units where the heat engines of the modular power units can be driven by fossil fuels as well as solar-derived heat. Since constraints on reliability result in the provision of a power generating capability that exceeds the constant demand level, efficient utilization of the power system requires battery storage. Tradeoffs regarding the optimum size of storage are investigated as a function of the number of power modules and the cost of the fossil fuel which is used to meet the demand when insolation is unavailable and storage is depleted.
Criteria for evaluation of reflective surface for parabolic dish concentrators
NASA Technical Reports Server (NTRS)
Bouquet, F.
1980-01-01
Commercial, second surface glass mirror are emphasized, but aluminum and metallized polymeric films are also included. Criteria for sealing solar mirrors in order to prevent environmental degradation and criteria for bonding sagged or bent mirrors to substrate materials are described. An overview of the technical areas involved in evaluating small mirror samples, sections, and entire large gores is presented. A basis for mirror criteria was established that eventually may become part of inspection and evaluation techniques for three dimensional parabolic reflective surfaces.
Parabolic tapers for overmoded waveguides
Doane, J.L.
1983-11-25
A waveguide taper with a parabolic profile, in which the distance along the taper axis varies as the square of the tapered dimension, provides less mode conversion than equal length linear tapers and is easier to fabricate than other non-linear tapers.
Fuse Protects Parabolic-Dish Solar Collector
NASA Technical Reports Server (NTRS)
Selcuk, M. K.
1983-01-01
Sliding barrel and shutter protect against overheating. Downward movement of shutter initiated by melting of fuse wire that suspends it. Shutter lowered or raised under operator's control by depressuring or pressurizing hydraulic cylinder.
Solar thermal parabolic dish energy applications
NASA Technical Reports Server (NTRS)
Pijawka, W.
1981-01-01
Vu-graphs are presented that show that applications are a viable distributed renewable power generation option. Quality energy can be produced in the form of electricity and high temperature heat. Modular systems are described that can be distributed to new or existing plants and that are mass producible with the associated economies of production.
ERIC Educational Resources Information Center
El Zubeir, Z.
1997-01-01
In El Sururab in rural Sudan, solar energy is used for cooking instead of wood. This study explored the efficiency of a hot-box type of solar cooker for storing heat and its effectiveness for different methods of cooking various foods used daily in El Sururab. Forty local women served as a respondent group. (PVD)
Parabolic dish systems at work - Applying the concepts
NASA Technical Reports Server (NTRS)
Marriott, A. T.
1981-01-01
An overview is given of parabolic dish solar concentrator application experiments being conducted by the U.S. Department of Energy. The 'engineering experiments' comprise the testing of (1) a small-community powerplant system, in conjunction with a grid-connected utility; (2) stand-alone applications at remote sites such as military installations, radar stations and villages; and (3) dish modules that can deliver heat for direct use in industrial processes. Applicability projections are based on a dish and receiver that use a Brayton engine with an engine/generator efficiency of 25% and a production level of up to 25,000 units per year. Analyses indicate that parabolic-dish power systems can potentially replace small, oil-fired power plants in all regions of the U.S. between 1985 and 1991.
Parabolic Trouogh Optical Characterization at the National Renewable Energy Laboratory
Wendelin, T. J.
2005-01-01
Solar parabolic trough power plant projects are soon to be implemented in the United States and internationally. In addition to these new projects, parabolic trough power plants totaling approximately 350 MW already exist within the United States and have operated for close to 20 years. As such, the status of the technology exists within several different phases. Theses phases include R&D, manufacturing and installation, and operations and maintenance. One aspect of successful deployment of this technology is achieving and maintaining optical performance. Different optical tools are needed to assist in improving initial designs, provide quality control during manufacture and assembly, and help maintain performance during operation. This paper discusses several such tools developed at SunLab (a joint project of the National Renewable Laboratory and Sandia National Laboratories) for these purposes. Preliminary testing results are presented. Finally, plans for further tool development are discussed.
scul
2002-11-27
solar-thermal power plants, parabolic through and central receiver systems, which apply concentrators .... this kind of chimney. They are best built free- ... vidual components on the plant's output and efficiency under realistic engineering and.
A Grinding Apparatus For Making A Middle-Size Parabolic Mirror Using The Link Mechanism Method
NASA Astrophysics Data System (ADS)
Shishido, Kora; Sugiura, Masao
1987-01-01
A large solar furnace that has a parabolic mirror with a diameter of 10m, a focal length of 3.2m and a heliostat mirror with an area of 15x15m was made by the authors at T6hoku University in 1962, and subsequently a small solar furnace having a parabolic mirror with a diameter of 1.5m, a focal -length of 0.5m and a heliostat mirror with an area of 2x2m was constructed at T6hoku Gakuin University in 1986. The large solar furnace could melt tungsten with a melting point of 3400°C, and the small solar furnace drove a stirling engine made in West Germany that had a rated power of 400W. The parabolic mirror of the segment type at TohokU University was made by a grinding apparatus that used a cam mechanism, and the parabolic mirror at T6hoku Gakuin University was made by an apparatus (hand-made by students)which employed a link mechanism to draw the parabolic curve. In this paper, the grinding apparatus used for making the segmental parabolic mirror with a diameter of 2-3m and a focal length of 0.5-1.0 m is reported. This mirror was used in a middle-size solar heat engine. The heat engine in this system was a Stirling engine with a rated power of 1-3KW, and the grinding apparatus (the precision parts moved in a linear track ) employed a compact link mechanism.
COVARIANCE STRUCTURE OF PARABOLIC STOCHASTIC PARTIAL DIFFERENTIAL EQUATIONS
Larsson, Stig
COVARIANCE STRUCTURE OF PARABOLIC STOCHASTIC PARTIAL DIFFERENTIAL EQUATIONS ANNIKA LANG, STIG LARSSON, AND CHRISTOPH SCHWAB Abstract. In this paper parabolic random partial differential equations and parabolic sto- chastic partial differential equations driven by a Wiener process are considered. A deter
Study on Pot Forming of Induction Heater Type Rice Cookers by Forging Cast Process
NASA Astrophysics Data System (ADS)
Ohnishi, Masayuki; Yamaguchi, Mitsugi; Ohashi, Osamu
This paper describes a study result on pot fabrication by the forging cast process of stainless steel with aluminum. Rice cooked with the new bowl-shaped pot for the induction heater type rice cookers is better tasting than rice cooked with the conventional cylindrical one, due to the achievement of better heat conduction and convection. The conventional pot is made of the clad sheet, consisting of stainless steel and aluminum. However, it is rather difficult to form a bowl shape from the clad sheet, primarily due to the problem of a material spring back. The fabrication of a new type of a pot was made possible by means of the adoption of a forging cast process instead of the clad sheet. In this process, iron powder is inserted between stainless steel and aluminum in order to alleviate the large difference on the coefficient of expansion between each material. It was made clear that the application of two kinds of iron particle, namely 10 ?m size powder on the stainless steel side and 44 ?m on the aluminum side, enables the joints to become strong enough. The joint strength of the new pot by this fabrication process was confirmed by the tests of the shear strength and the fatigue tests together with the stress analysis.
PARABOLIC BOUNDARY HARNACK PRINCIPLES IN DOMAINS ...
2013-12-31
types of the boundary Harnack principles for the parabolic equations: the forward one (also .... parabolic cylinders due to the time-lag issues and different scales in space and time ...... depending weather (x, t) ? ??k+1 is close to ?pD or not.
Renewable energy technologies for federal facilities: Solar water heating
1996-05-01
This sheet presents information on solar water heaters (passive and active), solar collectors (flat plate, evacuated tube, parabolic trough), lists opportunities for use of solar water heating, and describes what is required and the costs. Important terms are defined.
Overview of software development at the parabolic dish test site
NASA Technical Reports Server (NTRS)
Miyazono, C. K.
1985-01-01
The development history of the data acquisition and data analysis software is discussed. The software development occurred between 1978 and 1984 in support of solar energy module testing at the Jet Propulsion Laboratory's Parabolic Dish Test Site, located within Edwards Test Station. The development went through incremental stages, starting with a simple single-user BASIC set of programs, and progressing to the relative complex multi-user FORTRAN system that was used until the termination of the project. Additional software in support of testing is discussed including software in support of a meteorological subsystem and the Test Bed Concentrator Control Console interface. Conclusions and recommendations for further development are discussed.
On the parabolic-elliptic limit of the doubly parabolic Keller--Segel system modelling chemotaxis
Biler, Piotr
2008-01-01
We establish new convergence results, in strong topologies, for solutions of the parabolic-parabolic Keller--Segel system in the plane, to the corresponding solutions of the parabolic-elliptic model, as a physical parameter goes to zero. Our main tools are suitable space-time estimates, implying the global existence of slowly decaying (in general, nonintegrable) solutions for these models, under a natural smallness assumption.
Parabolic subgroups and Einstein solvmanifolds 1 . Einstein ,
Tamaru, Hiroshi
Parabolic subgroups and Einstein solvmanifolds 1 2 0 : Einstein . Einstein , , , nilpotency . , , , . , [35] ( [37] ). [36] , Einstein , . 1 (M, g) (solvmanifold) , M . . , . , , ( ) , . . Â· , Einstein ( , moduli ) . Einstein , Heber ([18]) . , Lauret ([27]) , Einstein . Â· , ( [21], [5], [15] ). , . Section 5
Federal Register 2010, 2011, 2012, 2013, 2014
2010-07-15
...solar energy generation project. The proposed Lathrop Wells Solar Facility project would consist of a concentrated solar power facility including a solar parabolic trough, photovoltaic panels, an electrical transmission substation, switchyard...
NASA Astrophysics Data System (ADS)
1986-08-01
This annual evaluation report provides the accomplishments and progress of government-funded activities initiated, renewed, or completed during Fiscal Year 1985 (October 1, 1984 through September 30, 1985). It highlights the program tasks conducted by participating national laboratories and by contracting industrial academic, or other research institutions. The focus of the STT Program is research and development leading to the commercial readiness of four primary solar thermal concepts: (1) central receiver; (2) parabolic dish; (3) parabolic trough; and (4) hemispherical bowl.
Kavanagh, Karen L.
Welcome to the Pressure Cooker: How Climate Change is Making Our World More Violent and Less Secure Hastings Climate Change: How Safe Are YOU? Series http://www.sfu.ca: Climate change threatens human se- curity in ways that are more numerous and more frightening than
Steadily translating parabolic dissolution fingers
Kondratiuk, Pawe?
2015-01-01
Dissolution fingers (or wormholes) are formed during the dissolution of a porous rock as a result of nonlinear feedbacks between the flow, transport and chemical reactions at pore surfaces. We analyze the shapes and growth velocities of such fingers within the thin-front approximation, in which the reaction is assumed to take place instantaneously with the reactants fully consumed at the dissolution front. We concentrate on the case when the main flow is driven by the constant pressure gradient far from the finger, and the permeability contrast between the inside and the outside of the finger is finite. Using Ivantsov ansatz and conformal transformations we find the family of steadily translating fingers characterized by a parabolic shape. We derive the reactant concentration field and the pressure field inside and outside of the fingers and show that the flow within them is uniform. The advancement velocity of the finger is shown to be inversely proportional to its radius of curvature in the small P\\'{e}clet...
A Process Heat Application Using Parabolic Trough Collector
NASA Astrophysics Data System (ADS)
Y?lmaz, ?brahim Halil; Söylemez, Mehmet Sait; Hayta, Hakan; Yumruta?, Recep
A pilot study has been performed based on a heat process application that is designed, installed and tested at Gaziantep University to establish the technical and economic feasibility of high temperature solar-assisted cooking process. The system has been designed to be satisfying the process conditions integrated with parabolic trough solar collector (PTSC). It is primarily consists of the PTSC array, auxiliary heater, plate type heat exchanger, cooking system and water heating tanks. In the operation of the process heat application, the energy required to cook wheat (used as cooking material) has been supplied from solar energy which is transferred to heat transfer fluid (HTF) by heat exchanging units and finally discharged to water in order to produce bulgur. The performance parameters of the sub-systems and the process compatibility have been accomplished depending on the system operation. In addition that the system performance of the high temperature solar heat process has been presented and the recommendations on its improvement have been evaluated by performing an experimental study. As a result that the use of solar energy in process heat application has been projected and its contribution to economics view with respect to conventional cooking systems has been conducted.
Large mass self-similar solutions of the parabolic-parabolic Keller--Segel model of chemotaxis
Biler, Piotr; Dolbeault, Jean
2009-01-01
In two space dimensions, the parabolic-parabolic Keller--Segel system shares many properties with the parabolic-elliptic Keller--Segel system. In particular, solutions globally exist in both cases as long as their mass is less than 8?. However, this threshold is not as clear in the parabolic-parabolic case as it is in the parabolic-elliptic case, in which solutions with mass above 8? always blow up. Here we study forward self-similar solutions of the parabolic-parabolic Keller--Segel system and prove that, in some cases, such solutions globally exist even if their total mass is above 8?, which is forbidden in the parabolic-elliptic case.
Elliptic and parabolic equations in fractured media
NASA Astrophysics Data System (ADS)
Yeh, Li-Ming
2015-12-01
The elliptic and the parabolic equations with Dirichlet boundary conditions in fractured media are considered. The fractured media consist of a periodic connected high permeability sub-region and a periodic disconnected matrix block subset with low permeability. Let ? ? (0, 1 ] denote the size ratio of the matrix blocks to the whole domain and let ?2 ? (0, 1 ] denote the permeability ratio of the disconnected subset to the connected sub-region. It is proved that the W 1, p norm of the elliptic and the parabolic solutions in the high permeability sub-region are bounded uniformly in ?, ?. However, the W 1, p norm of the solutions in the low permeability subset may not be bounded uniformly in ?, ?. For the elliptic and the parabolic equations in periodic perforated domains, it is also shown that the W 1, p norm of their solutions are bounded uniformly in ?.
Current and Future Economics of Parabolic Trough Technology
Price, H.; Mehos, M.; Kutscher, C.; Blair, N.
2007-01-01
Solar energy is the largest energy resource on the planet. Unfortunately, it is largely untapped at present, in part because sunlight is a very diffuse energy source. Concentrating solar power (CSP) systems use low cost reflectors to concentrate the sun's energy to allow it to be used more effectively. Concentrating solar power systems are also well suited for large solar power plants that can be connected into the existing utility infrastructure. These two facts mean that CSP systems can be used to make a meaningful difference in energy supply in a relatively short period. CSP plants are best suited for the arid climates in the Southwestern United States, Northern Mexico, and many desert regions around the globe. A recent Western Governors' Association siting study [1] found that the solar potential in the U.S. Southwest is at least 4 times the total U.S. electric demand even after eliminating urban areas, environmentally sensitive areas, and all regions with a ground slope greater than 1%.While it is currently not practical to power the whole county from the desert southwest, only a small portion of this area is needed to make a substantial contribution to future U.S. electric needs. Many of the best sites are near existing high-voltage transmission lines and close to major power load centers in the Southwest (Los Angeles, Las Vegas, and Phoenix). In addition, the power provided by CSP technologies has strong coincidence with peak electric demand, especially in the Southwest where peak demand corresponds in large part to air conditioning loads. Parabolic troughs currently represent the most cost-effective CSP technology for developing large utility-scale solar electric power systems. These systems are also one of the most mature solar technologies, with commercial utility-scale plants that have been operating for over 20 years. In addition, substantial improvements have been made to the technology in recent years including improved efficiency and the addition of thermal energy storage. The main issue for parabolic trough technology is that the cost of electricity is still higher than the cost of electricity from conventional natural gas-fired power plants. Although higher natural gas prices are helping to substantially reduce the difference between the cost of electricity from solar and natural gas plants, in the near-term increased incentives such as the 30% Investment Tax Credit (ITC) are needed to make CSP technology approach competitiveness with natural gas power on a financial basis. In the longer term, additional reductions in the cost of the technology will be necessary. This paper looks at the near-term potential for parabolic trough technology to compete with conventional fossil power resources in the firm, intermediate load power market and at the longer term potential to compete in the baseload power market. The paper will consider the potential impact of a reduced carbon emissions future.
Transformation of barchans into parabolic dunes under the
Harting, Jens
Transformation of barchans into parabolic dunes under the influence of vegetation O.Duran, H.Tsoar, V.Schatz & H.Herrmann #12;Introduction Parabolic dunes: Barchan dunes: #12;Transformation of parabolic dunes into barchans and viceversa Introduction #12;Models vnvnv hthhth +=++ )()( 1 (1) t hhH dt dh
Development status of the PDC-1 Parabolic Dish Concentrator
NASA Technical Reports Server (NTRS)
Thostesen, T.; Soczak, I. F.; Pons, R. L.
1982-01-01
The status of development of the 12 m diameter parabolic dish concentrator which is planned for use with the Small Community Solar Thermal Power System. The PDC-1 unit features the use of plastic reflector film bonded to structural plastic gores supported by front-bracing steel ribs. An elevation-over-azimuth mount arrangement is employed, with a conventional wheel-and-track arrangement; outboard trunnions permit the dish to be stored in the face down position, with the added advantage of easy access to the power conversion assembly. The control system is comprised of a central computer (LSI 1123), a manual control panel, a concentrator control unit, two motor controllers, a Sun sensor, and two angular position resolvers. The system is designed for the simultaneous control of several concentrators. The optical testing of reflective panels is described.
A PARABOLIC ALMOST MONOTONICITY FORMULA Introduction In ...
2006-07-07
University and the Royal Institute of Technology, respectively, and they thank the universities ... Finally, let us make a remark on the proof of the parabolic almost monotonic- ... almost monotonicity formula (Theorem III) with more features of the monotonicity ...... Also, the boundedness of both u and (???s)u alone implies.
The linear regulator problem for parabolic systems
NASA Technical Reports Server (NTRS)
Banks, H. T.; Kunisch, K.
1983-01-01
An approximation framework is presented for computation (in finite imensional spaces) of Riccati operators that can be guaranteed to converge to the Riccati operator in feedback controls for abstract evolution systems in a Hilbert space. It is shown how these results may be used in the linear optimal regulator problem for a large class of parabolic systems.
Parabolic Dish Concentrator (PDC-2) Development
NASA Technical Reports Server (NTRS)
Rafinejad, D.
1984-01-01
The design of the Parabolic Dish Concentrator (PDC-2) is described. The following five subsystems of the concentrator are discussed: (1) reflective surface subsystem, (2) support structure subsystem, (3) foundation, (4) drive subsystem, and (5) electrical and control subsystem. The status of the PDC-2 development project is assessed.
Status of the current parabolic dish technology
NASA Technical Reports Server (NTRS)
Sumrall, C.
1981-01-01
Vu-graphs are presented that show that point focus distributed receiver distributed generation systems are cost competitive with current utilities. System cost caveats and typical power module costs are described. Major problems inhibiting commercialization of the parabolic dish technology were reviewed.
Riesz Potentials and Nonlinear Parabolic Equations
NASA Astrophysics Data System (ADS)
Kuusi, Tuomo; Mingione, Giuseppe
2014-06-01
The spatial gradient of solutions to nonlinear degenerate parabolic equations can be pointwise estimated by the caloric Riesz potential of the right hand side datum, exactly as in the case of the heat equation. Heat kernels type estimates persist in the nonlinear case.
Finite time blow-up for a one-dimensional quasilinear parabolic-parabolic chemotaxis system
CieĹ?lak, Tomasz
2008-01-01
Finite time blow-up is shown to occur for solutions to a one-dimensional quasilinear parabolic-parabolic chemotaxis system as soon as the mean value of the initial condition exceeds some threshold value. The proof combines a novel identity of virial type with the boundedness from below of the Liapunov functional associated to the system, the latter being peculiar to the one-dimensional setting.
NASA Technical Reports Server (NTRS)
Lathrop, J. W.; Prince, J. L.
1979-01-01
Results obtained include the definition of a simplified stress test schedule for terrestrial solar cells based on the work performed during the first program year, and the design and fabrication of improved jigs and fixtures for electrical measurement and stress testing. Implementation of these advanced techniques for accelerated stress testing is underway on three solar cell types. In addition, review of the literature on second quadrant phenomena was begun and some preliminary second-quadrant electrical measurements were performed. Results obtained at the first down time for 75 C B-T testing and biased and unbiased T-H pressure cooker testing of type F cells showed little or no degradation in electrical parameters. Significant physical effects (large solder bubbles) were noted for type F cells subjected to the pressure cooker stress test.
Federal Register 2010, 2011, 2012, 2013, 2014
2011-05-13
...rows of parabolic mirrors focusing solar energy on collector tubes. The tubes...the project area as suitable for solar energy production. In addition to the...project area as available to future solar energy power generation projects;...
Solar Disinfection of MODS Mycobacterial Cultures in Resource-Poor Settings
Nathavitharana, Ruvandhi; Coronel, Jorge; Moore, David A. J.
2007-01-01
Introduction Safe disposal of TB culture material in which the infectious burden of clinical samples has been greatly amplified is an important challenge in resource-limited settings. The bactericidal capacity of solar cookers has been demonstrated previously for conventional bacteria and contaminated clinical waste. We investigated the use of a simple solar cooker for the sterilization of mycobacterial broth cultures from the microscopic observation drug susceptibility assay (MODS). Methods Simulated TB culture materials were prepared by inoculating 24-well MODS plates with 500 µL of a known concentration of Mycobacterium bovis BCG. In a series of experiments, samples were simultaneously placed inside a box-type solar cooker and control box and removed at timepoints between 15 minutes and 6 hours. Quantitative cultures were performed using retrieved samples to determine sterilization effect. Results All cultures from the control box were positive at or within 1–4 logs of inoculation concentration. Simulated culture plates at concentrations from 103colony-forming-units (CFU)/ml to 107 CFU/ml were completely sterilized after only one hour of cooker exposure, at temperatures between 50–102°C. At 109 CFU/ml (far in excess of diagnostic cultures), it was only possible to recover mycobacterial growth in plates removed after 15 minutes. By 30 minutes all plates were effectively sterilized. Discussion Solar disinfection provides a very effective, safe and low-cost alternative to conventional equipment used for disposal of mycobacterial culture material. Effect of climatic conditions and optimal operating procedure remain to be defined. PMID:17971863
Prolonging Microgravity on Parabolic Airplane Flights
NASA Technical Reports Server (NTRS)
Robinson, David W.
2003-01-01
Three techniques have been proposed to prolong the intervals of time available for microgravity experiments aboard airplanes flown along parabolic trajectories. Typically, a pilot strives to keep an airplane on such a trajectory during a nominal time interval as long as 25 seconds, and an experimental apparatus is released to float freely in the airplane cabin to take advantage of the microgravitational environment of the trajectory for as long as possible. It is usually not possible to maintain effective microgravity during the entire nominal time interval because random aerodynamic forces and fluctuations in pilot control inputs cause the airplane to deviate slightly from a perfect parabolic trajectory, such that the freely floating apparatus bumps into the ceiling, floor, or a wall of the airplane before the completion of the parabola.
Essential Parabolic Structures and Their Infinitesimal Automorphisms
NASA Astrophysics Data System (ADS)
Alt, Jesse
2011-04-01
Using the theory of Weyl structures, we give a natural generalization of the notion of essential conformal structures and conformal Killing fields to arbitrary parabolic geometries. We show that a parabolic structure is inessential whenever the automorphism group acts properly on the base space. As a corollary of the generalized Ferrand-Obata theorem proved by C. Frances, this proves a generalization of the ''Lichnérowicz conjecture'' for conformal Riemannian, strictly pseudo-convex CR, and quaternionic/octonionic contact manifolds in positive-definite signature. For an infinitesimal automorphism with a singularity, we give a generalization of the dictionary introduced by Frances for conformal Killing fields, which characterizes (local) essentiality via the so-called holonomy associated to a singularity of an infinitesimal automorphism.
Nanofocusing Parabolic Refractive X-Ray Lenses
Schroer, C.G.; Kuhlmann, M.; Hunger, U.T.; Guenzler, T.F.; Kurapova, O.; Feste, S.; Lengeler, B.; Drakopoulos, M.; Somogyi, A.; Simionovici, A. S.; Snigirev, A.; Snigireva, I.
2004-05-12
Parabolic refractive x-ray lenses with short focal distance can generate intensive hard x-ray microbeams with lateral extensions in the 100nm range even at short distance from a synchrotron radiation source. We have fabricated planar parabolic lenses made of silicon that have a focal distance in the range of a few millimeters at hard x-ray energies. In a crossed geometry, two lenses were used to generate a microbeam with a lateral size of 330nm by 110nm at 25keV in a distance of 41.8m from the synchrotron radiation source. First microdiffraction and fluorescence microtomography experiments were carried out with these lenses. Using diamond as lens material, microbeams with lateral size down to 20nm and below are conceivable in the energy range from 10 to 100keV.
NASA Astrophysics Data System (ADS)
Huettenhoelscher, N.; Bergmann, K.
1981-11-01
The feasibility of using solar energy in developing countries for baking ceramic construction materials was investigated. The solar high temperature kiln is described. It uses two parabolic concentrators which direct available radiation into the baking chamber. The Sun tracker has only one axis. Preliminary test results with the prototype kiln were satisfactory.
Excitonic spectra of wide parabolic quantum wells
NASA Astrophysics Data System (ADS)
Czajkowski, Gerard; Zieli?ska-Raczy?ska, Sylwia; Ziemkiewicz, David
2015-09-01
The optical properties of wide quantum wells are considered, taking into account the screened electron-hole interaction potential and parabolic confinement potentials, different for the electrons and for the holes. The role of the interaction potential which mixes the energy states according to different quantum numbers is stressed. The results obtained by our method are in agreement with the observed spectra and give the possibility to the assessment of the resonances.
Solar energy concentrator design and operation. Citations from the NTIS data base
NASA Astrophysics Data System (ADS)
Hundemann, A. S.
1980-09-01
Government funded research on the design and operation of various types of solar energy concentrators is discussed. Abstracts cover the efficiency and optimization of Fresnel lenses, V-through concentrators, flat plate and parabolic reflectors, compound parabolic concentrators used in solar photovoltaic conversion and heliostat systems. A few abstracts deal with heat loss and cost studies.
Near-term improvements in parabolic troughs: an economic and performance assessment
Gee, R.; Murphy, L.M.
1981-08-01
Improved parabolic-trough concentrating collectors will result from better design, improved fabrication techniques, and the development and utilization of improved materials. This analysis qualifies the performance potential of various parabolic-trough component improvements from a systems viewpoint and uses these performance data to determine the worth of each improvement on an economic basis. The improvements considered are evacuated receivers, silvered-glass reflectors, improved receiver, selective coatings, higher optical accuracy concentrations, and higher transmittance receiver glazings. Upper-bound costs for each improvement are provided as well as estimates of the increased solar system rates of return that are made possible by these improvements. The performance and economic potential of some of these improvements are shown to be substantial, especially at higher collector operating temperatures.
Advances in solar cooking: Proceedings of the first world conference on solar cooking
Pejack, E.
1992-12-31
Population growth and resource depletion have led to a need for new sources of cooking fuel in developing countries. Many poor villagers spend half of their time, or half of their income obtaining cooking fuel. Solar cooking can meet the needs of many of these people. People from eighteen countries met at this world conference to share experiences with design and performance of cookers, food, nutrition and health issues, and information dissemination strategies. A total of 27 individual papers were indexed separately for the data base.
Femtosecond parabolic pulse shaping in normally dispersive optical fibers.
Sukhoivanov, Igor A; Iakushev, Sergii O; Shulika, Oleksiy V; Díez, Antonio; Andrés, Miguel
2013-07-29
Formation of parabolic pulses at femtosecond time scale by means of passive nonlinear reshaping in normally dispersive optical fibers is analyzed. Two approaches are examined and compared: the parabolic waveform formation in transient propagation regime and parabolic waveform formation in the steady-state propagation regime. It is found that both approaches could produce parabolic pulses as short as few hundred femtoseconds applying commercially available fibers, specially designed all-normal dispersion photonic crystal fiber and modern femtosecond lasers for pumping. The ranges of parameters providing parabolic pulse formation at the femtosecond time scale are found depending on the initial pulse duration, chirp and energy. Applicability of different fibers for femtosecond pulse shaping is analyzed. Recommendation for shortest parabolic pulse formation is made based on the analysis presented. PMID:23938650
NASA Astrophysics Data System (ADS)
Chong, Kok-Keong; Yew, Tiong-Keat; Wong, Chee-Woon; Tan, Ming-Hui; Tan, Woei-Chong; Lai, An-Chow; Lim, Boon-Han; Lau, Sing-Liong; Rahman, Faidz Abdul
2015-04-01
Solar concentrating device plays an important role by making use of optical technology in the design, which can be either reflector or lens to deliver high flux of sunlight onto the Concentrator Photovoltaic (CPV) module receiver ranging from hundreds to thousand suns. To be more competitive compared with fossil fuel, the current CPV systems using Fresnel lens and Parabolic dish as solar concentrator that are widely deployed in United States, Australia and Europe are facing great challenge to produce uniformly focused sunlight on the solar cells as to reduce the cost of electrical power generation. The concept of non-imaging optics is not new, but it has not fully explored by the researchers over the world especially in solving the problem of high concentration solar energy, which application is only limited to be a secondary focusing device or low concentration device using Compound Parabolic Concentrator. With the current advancement in the computer processing power, we has successfully invented the non-imaging dish concentrator (NIDC) using numerical simulation method to replace the current parabolic dish as primary focusing device with high solar concentration ratio (more than 400 suns) and large collective area (from 25 to 125 m2). In this paper, we disclose our research and development on dense array CPV system based on non-imaging optics. The geometry of the NIDC is determined using a special computational method. In addition, an array of secondary concentrators, namely crossed compound parabolic concentrators, is also proposed to further focus the concentrated sunlight by the NIDC onto active area of solar cells of the concentrator photovoltaic receiver. The invention maximizes the absorption of concentrated sunlight for the electric power generation system.
NASA Astrophysics Data System (ADS)
1984-08-01
The accomplishments and progress of the US Department of energy solar thermal technology (STT) program during FY 1983 are documented. The focus of the STT program is research and development leading to the commercial readiness of three primary solar thermal concepts: the central receiver, parabolic dish, and parabolic trough. The hemispherical bowl and salt-gradient solar pond are also being studied. This development effort is complemented by numerous research and planning activities. A brief description of each technology and highlights of the fiscal year's technical activities is given. FY 1983 accomplishments are enumerated and a bibliography, list of contacts, acronyms, and definitions of terms relevant to solar thermal technology and the STT program are included.
Spectral methods in time for parabolic problems
NASA Technical Reports Server (NTRS)
Tal-Ezer, H.
1985-01-01
A pseudospectral explicit scheme for solving linear, periodic, parabolic problems is described which has infinite accuracy both in time and in space. The high accuracy is achieved while the time resolution parameter M ( = ) (1/delta t) for time marching algorithm) and the space resolution parameter N B = O(1/detla x) have to satisfy M = O(N sup/+epsilon) epsilon O, compared to the common stability condition M = O(N sup 2) which has to be satisfied in any explicit finite order time algorithm.
On the parallel solution of parabolic equations
NASA Technical Reports Server (NTRS)
Gallopoulos, E.; Saad, Youcef
1989-01-01
Parallel algorithms for the solution of linear parabolic problems are proposed. The first of these methods is based on using polynomial approximation to the exponential. It does not require solving any linear systems and is highly parallelizable. The two other methods proposed are based on Pade and Chebyshev approximations to the matrix exponential. The parallelization of these methods is achieved by using partial fraction decomposition techniques to solve the resulting systems and thus offers the potential for increased time parallelism in time dependent problems. Experimental results from the Alliant FX/8 and the Cray Y-MP/832 vector multiprocessors are also presented.
Parabolic PDEs and Deterministic Games Robert V. Kohn
Parabolic PDEs and Deterministic Games Robert V. Kohn Courant Institute, NYU Joint work with Sylvia Serfaty ICIAM07, Zurich, July 2007 Robert V. Kohn Courant Institute, NYU Parabolic PDEs and Deterministic-Lax solution formula; and finance, for example through Merton's analysis of portfolio optimization. Robert V
THE CAUCHY PROBLEM FOR THIN FILM AND OTHER NONLINEAR PARABOLIC
Moroz, Vitaly
THE CAUCHY PROBLEM FOR THIN FILM AND OTHER NONLINEAR PARABOLIC PDEs (An Introduction to Higher-Order Diffusion Theory) Summer School on Nonlinear Parabolic Equations and Applications Math. Dept., Swansea Univ) as t +, large-time behaviour, and (ii) blow-up behaviour, as t T-
Parabolic Dish Solar Thermal Power Annual Program Review Proceedings
NASA Technical Reports Server (NTRS)
Holbeck, H. J.
1981-01-01
The development and testing of concentrators, receivers, and power conversion units are reported. System design and development for engineering experiments are described. Economic analysis and market assessments for advanced development activities are discussed. Technology development issues and application/user needs are highlighted.
THE PARABOLIC JET STRUCTURE IN M87 AS A MAGNETOHYDRODYNAMIC NOZZLE
Nakamura, Masanori; Asada, Keiichi E-mail: asada@asiaa.sinica.edu.tw
2013-10-01
The structure and dynamics of the M87 jet from sub-milliarcsec to arcsecond scales are continuously examined. We analyzed the Very Long Baseline Array archival data taken at 43 and 86 GHz to measure the size of very long baseline interferometry (VLBI) cores. Millimeter/sub-millimeter VLBI cores are considered as innermost jet emissions, which has been originally suggested by Blandford and Königl. Those components fairly follow an extrapolated parabolic streamline in our previous study so that the jet has a single power-law structure with nearly 5 orders of magnitude in the distance starting from the vicinity of the supermassive black hole (SMBH), less than 10 Schwarzschild radius (r{sub s}). We further inspect the jet parabolic structure as a counterpart of the magnetohydrodynamic (MHD) nozzle in order to identify the property of a bulk acceleration. We interpret that the parabolic jet consists of Poynting-flux dominated flows, powered by large-amplitude, nonlinear torsional Alfvén waves. We examine the non-relativistic MHD nozzle equation in a parabolic shape. The nature of trans-fast magnetosonic flow is similar to the one of transonic solution of Parker's hydrodynamic solar wind; the jet becomes super-escape as well as super-fast magnetosonic at around ?10{sup 3} r{sub s}, while the upstream trans-Alfvénic flow speed increases linearly as a function of the distance at ?10{sup 2}-10{sup 3} r{sub s}. We here point out that this is the first evidence to identify these features in astrophysical jets. We propose that the M87 jet is magnetically accelerated, but thermally confined by the stratified interstellar medium inside the sphere of gravitational influence of the SMBH potential, which may be a norm in active galactic nucleus jets.
NASA Astrophysics Data System (ADS)
Schimmel, W. P., Jr.; Lukens, L. L.
1981-11-01
An economic analysis is presented for a combined parabolic trough solar/fossil fuel hybrid power plant. Applications are considered for investor-owned utilities and industries with stockholders and bond purchasers. Annual levelized revenues are calculated, based on the capital cost of equipment, annual operations and maintenance, and a rising cost of fossil fuel. The units of heat are considered as equal in value from each source, and project return on equity for an American Southwest user of the hybrid systems are calculated to show an annual project return on equity of 21% for a utility and 25% for an industry in 1985. Analysis of the total fuel replaced by a solar reheat system for a gas-fueled boiler system shows that a 20% reduction in fuel costs can be obtained by a 10% increase in the plant costs to include the solar reheat system furnishing low-temperature heat in 1985.
Solid-dielectric compound parabolic concentrators: on their use with photovoltaic devices.
Goodman, N B; Ignatius, R; Wharton, L; Winston, R
1976-10-01
Prototype solid dielectric compound parabolic concentrators have been made and tested. By means of the geometry and refractive properties of a transparent solid they provide a technique for increasing the power output of silicon solar cells exposed to the sun by an amount nearly equal to the increase in effective collecting area. The response is uniform over a large angle which eliminates the necessity of diurnal tracking of the sun. The technique can be applied to the construction of thin panels and has the potential for significantly reducing, their cost per unit area. PMID:20165416
Heat and electricity from the sun using parabolic dish collector systems
NASA Technical Reports Server (NTRS)
Truscello, V. C.; Williams, A. N.
1979-01-01
The paper investigates point focus distributed receiver (PFDR) solar thermal technology for the production of electric power and of industrial process heat. Attention is given to a thermal systems project conducted by JPL under DOE sponsorship. It is reported that project emphasis is on the development of cost-effective systems which will accelerate the commercialization and industrialization of plants up to 10 MWe, using parabolic dish collectors. Also discussed are the characteristics of PFDR systems, the cost targets for major systems hardware, and markets for this technology. Finally, the present system status of the technology development effort is discussed.
Parabolic systems with nonlinear competitive interactions
Cosner, C.; Lenhart, S.; Protopopescu, V.
1989-01-01
A parabolic system with nonlinear local or nonlocal interactions is considered, with specific applications to the description of competition/combat situations. Global existence and comparison results are proven under suitable assumptions on the interaction terms. Comparisons with solutions of the ''equivalent'' ordinary differential (space independent) model, that has been previously used in modelling combat are of special interest. The stationary state of such a system--corresponding to a stalemate--is also considered. Under certain conditions on the interaction, domain size and boundary conditions, a uniqueness result is obtained for the stationary state. A simple example shows that these conditions are sharp and uniqueness may be lost when they are not fulfilled. 15 refs.
Nonuniform depth grids in parabolic equation solutions.
Sanders, William M; Collins, Michael D
2013-04-01
The parabolic wave equation is solved using a finite-difference solution in depth that involves a nonuniform grid. The depth operator is discretized using Galerkin's method with asymmetric hat functions. Examples are presented to illustrate that this approach can be used to improve efficiency for problems in ocean acoustics and seismo-acoustics. For shallow water problems, accuracy is sensitive to the precise placement of the ocean bottom interface. This issue is often addressed with the inefficient approach of using a fine grid spacing over all depth. Efficiency may be improved by using a relatively coarse grid with nonuniform sampling to precisely position the interface. Efficiency may also be improved by reducing the sampling in the sediment and in an absorbing layer that is used to truncate the computational domain. Nonuniform sampling may also be used to improve the implementation of a single-scattering approximation for sloping fluid-solid interfaces. PMID:23556565
Graviresponses of Paramecium biaurelia during parabolic flights.
Krause, Martin; Bräucker, Richard; Hemmersbach, Ruth
2006-12-01
The thresholds of graviorientation and gravikinesis in Paramecium biaurelia were investigated during the 5th DLR (German Aerospace Center) parabolic-flight campaign at Bordeaux in June 2003. Parabolic flights are a useful tool for the investigation of swimming behaviour in protists at different accelerations. At normal gravity (1 g) and hypergravity (1 g to 1.8 g), precision of orientation and locomotion rates depend linearly on the applied acceleration as seen in earlier centrifuge experiments. After transition from hypergravity to decreased gravity (minimal residual acceleration of <10(-2) g), graviorientation as well as gravikinesis show a full relaxation with different kinetics. The use of twelve independent cell samples per flight guarantees high data numbers and secures the statistical significance of the obtained data. The relatively slow change of acceleration between periods of microgravity and hypergravity (0.4 g/s) enabled us to determine the thresholds of graviorientation at 0.6 g and of gravikinesis at 0.4 g. The gravity-unrelated propulsion rate of the sample was found to be 874 microm/s, exceeding the locomotion rate of horizontally swimming cells (855 microm/s). The measured thresholds of graviresponses were compared with data obtained from earlier centrifuge experiments on the sounding rocket Maxus-2. Measured thresholds of gravireactions indicate that small energies, close to the thermal noise level, are sufficient for the gravitransduction process. Data from earlier hypergravity experiments demonstrate that mechanosensitive ion channels are functioning over a relative wide range of acceleration. From this, we may speculate that gravireceptor channels derive from mechanoreceptor channels. PMID:17180491
Parabolic features and the erosion rate on Venus
NASA Technical Reports Server (NTRS)
Strom, Robert G.
1993-01-01
The impact cratering record on Venus consists of 919 craters covering 98 percent of the surface. These craters are remarkably well preserved, and most show pristine structures including fresh ejecta blankets. Only 35 craters (3.8 percent) have had their ejecta blankets embayed by lava and most of these occur in the Atla-Beta Regio region; an area thought to be recently active. parabolic features are associated with 66 of the 919 craters. These craters range in size from 6 to 105 km diameter. The parabolic features are thought to be the result of the deposition of fine-grained ejecta by winds in the dense venusian atmosphere. The deposits cover about 9 percent of the surface and none appear to be embayed by younger volcanic materials. However, there appears to be a paucity of these deposits in the Atla-Beta Regio region, and this may be due to the more recent volcanism in this area of Venus. Since parabolic features are probably fine-grain, wind-deposited ejecta, then all impact craters on Venus probably had these deposits at some time in the past. The older deposits have probably been either eroded or buried by eolian processes. Therefore, the present population of these features is probably associated with the most recent impact craters on the planet. Furthermore, the size/frequency distribution of craters with parabolic features is virtually identical to that of the total crater population. This suggests that there has been little loss of small parabolic features compared to large ones, otherwise there should be a significant and systematic paucity of craters with parabolic features with decreasing size compared to the total crater population. Whatever is erasing the parabolic features apparently does so uniformly regardless of the areal extent of the deposit. The lifetime of parabolic features and the eolian erosion rate on Venus can be estimated from the average age of the surface and the present population of parabolic features.
Harrison, T.D.
1981-03-01
Sandia National Laboratories, Albuquerque (SNLA), is currently conducting a program to predict the performance and measure the characteristics of commercially available solar collectors that have the potential for use in industrial process heat and enhanced oil recovery applications. The thermal performance predictions for the Solar Kinetics solar line-focusing parabolic trough collector for five cities in the US are presented. (WHK)
NASA Technical Reports Server (NTRS)
Hale, R. R. (inventor); Mcdougal, A. R.
1984-01-01
A module is described with a receiver having a solar energy acceptance opening and supported by a mounting ring along the optic axis of a parabolic mirror in coaxial alignment for receiving solar energy from the mirror, and a solar flux modulator plate for varying the quantity of solar energy flux received by the acceptance opening of the module. The modulator plate is characterized by an annular, plate-like body, the internal diameter of which is equal to or slightly greater than the diameter of the solar energy acceptance opening of the receiver. Slave cylinders are connected to the modulator plate for supporting the plate for axial displacement along the axis of the mirror, therby shading the opening with respect to solar energy flux reflected from the surface of the mirror to the solar energy acceptance opening.
Energy 101: Concentrating Solar Power
None
2013-05-29
From towers to dishes to linear mirrors to troughs, concentrating solar power (CSP) technologies reflect and collect solar heat to generate electricity. A single CSP plant can generate enough power for about 90,000 homes. This video explains what CSP is, how it works, and how systems like parabolic troughs produce renewable power. For more information on the Office of Energy Efficiency and Renewable Energy's CSP research, see the Solar Energy Technology Program's Concentrating Solar Power Web page at http://www1.eere.energy.gov/solar/csp_program.html.
Water Use in Parabolic Trough Power Plants: Summary Results from WorleyParsons' Analyses
Turchi, C. S.; Wagner, M. J.; Kutscher, C. F.
2010-12-01
The National Renewable Energy Laboratory (NREL) contracted with WorleyParsons Group, Inc. to examine the effect of switching from evaporative cooling to alternative cooling systems on a nominal 100-MW parabolic trough concentrating solar power (CSP) plant. WorleyParsons analyzed 13 different cases spanning three different geographic locations (Daggett, California; Las Vegas, Nevada; and Alamosa, Colorado) to assess the performance, cost, and water use impacts of switching from wet to dry or hybrid cooling systems. NREL developed matching cases in its Solar Advisor Model (SAM) for each scenario to allow for hourly modeling and provide a comparison to the WorleyParsons results.Our findings indicate that switching from 100% wet to 100% dry cooling will result in levelized cost of electricity (LCOE) increases of approximately 3% to 8% for parabolic trough plants throughout most of the southwestern United States. In cooler, high-altitude areas like Colorado's San Luis Valley, WorleyParsons estimated the increase at only 2.5%, while SAM predicted a 4.4% difference. In all cases, the transition to dry cooling will reduce water consumption by over 90%. Utility time-of-delivery (TOD) schedules had similar impacts for wet- and dry-cooled plants, suggesting that TOD schedules have a relatively minor effect on the dry-cooling penalty.
QUANTUM UNIQUE ERGODICITY FOR PARABOLIC JENS MARKLOF AND ZE '
translations of the twoÂ torus, the parabolic analogues of Arnold's cat maps. These maps are classically of the central problems of ``Quantum Chaos'' is the question of the asymptotic behaviour of eigenmodes
Off-axis parabolic optical relays: almost perfect imaging
NASA Astrophysics Data System (ADS)
Holdsworth, John L.; Sharafutdinova, Galiya; Sanderson, Michael J.; van Helden, Dirk F.
2011-09-01
Off-axis parabolic elements have found application in Tera-Hertz imaging and new application in two-photon microscopy scan engines. Both these applications demand spatial and temporal precision in photon location. This modelling work examines how close off-axis parabolic elements are to the perfect image relay by calculating the geometrical performance metrics of spot diagrams, point spread functions and wavefront distortion for different arrangements of off-axis parabolas and a parabolic torus when compared to a close-coupled two mirror scan engine. Results identify the off-axis parabolic elements as a superior scan engine particularly in wide-field scan instruments. When within the optimum beam size versus parabola focus length ratio, the imaging of these systems is superb.
JACQUET MODULES OF PARABOLICALLY INDUCED REPRESENTATIONS AND WEYL GROUPS
Ban, Dubravka
JACQUET MODULES OF PARABOLICALLY INDUCED REPRESENTATIONS AND WEYL GROUPS DUBRAVKA BAN Abstract Classification. 22E50. 1 #12;2 DUBRAVKA BAN In Section 5, we consider an intermediate standard Levi subgroup N
Detail, external parabolic antenna (later addition). Note how waveguide was ...
Detail, external parabolic antenna (later addition). Note how waveguide was cut to remove active portion of antenna. - Western Union Telegraph Company, Jennerstown Relay, Laurel Summit Road off U.S. 30, Laughlintown, Westmoreland County, PA
Superconvergence of the mixed nite element approximations to parabolic equations
Ewing, Richard E.
Richard Ewing Raytcho Lazarov y Abstract Semidiscrete mixed nite element approximation to parabolic, see, e.g., Duran 7], Douglas and Wang 6], Wang 18], and Ewing, Lazarov and Wang 9]. The corresponding
FINITE VOLUME ELEMENT APPROXIMATIONS OF INTEGRODIFFERENTIAL PARABOLIC PROBLEMS
Ewing, Richard E.
FINITE VOLUME ELEMENT APPROXIMATIONS OF INTEGRODIFFERENTIAL PARABOLIC PROBLEMS RICHARD E. EWING Institute for Scientific Computation, Texas A&M University, College Station, TX 778433404, Email: ewing
Potential for using parabolic trough collectors to supplement power cycle boilers
NASA Astrophysics Data System (ADS)
Schimmel, W. P., Jr.; Lukens, L. L.
1981-11-01
The advantage of such a system is that solar energy is used to heat the water in a steam Rankine cycle device up to the superheat regime, thus displacing the fossil fuel usually required. The temperature associated with this portion of the power cycle is typically on the order of 320 C or less, which makes it compatible with current parabolic trough collector systems. A system model which lends itself to optimization studies was constructed and exercised over a range of the multiparameter space involved. The collector field, storage, supplementary fossil boiler and superheater, and turbine/generator traded off to obtain a series of economically optimal systems for various years and solar fractions.
On two parabolic systems: Convergence and blowup
NASA Astrophysics Data System (ADS)
Huang, Yamin
1998-12-01
This dissertation studies two parabolic systems. It consists of two parts. In part one (chapter one), we prove a convergence result, namely, the solution (AK,/ BK) of a system of chemical diffusion-reaction equations (with reaction rate K) converges to the solution (A, B) of a diffusion- instantaneous-reaction equation. To prove our main result, we use some L1 and L2 'energy' estimates and a compactness result due to Aubin (1). As a by-product we also prove that as K approaches infinity, the limit solution exhibits phase separation between A and B. In part two (chapter two), we study the blowup rate for a system of heat equations ut=/Delta u,/ vt=/Delta v in a bounded domain ?times(0,T) coupled in the nonlinear Neumann boundary conditions [/partial u/over/partial n]=vp,/ [/partial v/over/partial n]=uq on ?Omega×[ 0,T), where p>0,/ q>0,/ pq>1 and n is the exterior normal vector on ?Omega. Under certain assumptions, we establish exact blowup rate which generalizes the corresponding results of some authors' recent work including Deng (2), Deng-Fila-Levine (3) and Hu-Yin (4). ftn (1) J. P. A scUBIN, Un theoreme de compacite, C. R. Acad. Sci., 256(1963), pp. 5042-5044. (2) K. D scENG, Blow-up rates for parabolic systems, Z. Angew. Math. Phys., 47(1996), No. 1, pp. 132-143. (3) K. D scENG, M. F scILA AND H. A. L scEVINE, On critical exponents for a system of heat equations coupled in the boundary conditions, Acta Math. Univ. Comenian. (N.S.), 36(1994), No. 2, pp. 169-192. (4) B. H scU scAND H. M. Y scIN, The profile near blowup time for solutions of the heat equation with a nonlinear boundary condition, Trans. Amer. Math. Soc., 346(1994), pp. 117-135.
Parabolic Trough Collector Cost Update for the System Advisor Model (SAM)
Kurup, Parthiv; Turchi, Craig S.
2015-11-01
This report updates the baseline cost for parabolic trough solar fields in the United States within NREL's System Advisor Model (SAM). SAM, available at no cost at https://sam.nrel.gov/, is a performance and financial model designed to facilitate decision making for people involved in the renewable energy industry. SAM is the primary tool used by NREL and the U.S. Department of Energy (DOE) for estimating the performance and cost of concentrating solar power (CSP) technologies and projects. The study performed a bottom-up build and cost estimate for two state-of-the-art parabolic trough designs -- the SkyTrough and the Ultimate Trough. The SkyTrough analysis estimated the potential installed cost for a solar field of 1500 SCAs as $170/m^{2} +/- $6/m^{2}. The investigation found that SkyTrough installed costs were sensitive to factors such as raw aluminum alloy cost and production volume. For example, in the case of the SkyTrough, the installed cost would rise to nearly $210/m^{2} if the aluminum alloy cost was $1.70/lb instead of $1.03/lb. Accordingly, one must be aware of fluctuations in the relevant commodities markets to track system cost over time. The estimated installed cost for the Ultimate Trough was only slightly higher at $178/m^{2}, which includes an assembly facility of $11.6 million amortized over the required production volume. Considering the size and overall cost of a 700 SCA Ultimate Trough solar field, two parallel production lines in a fully covered assembly facility, each with the specific torque box, module and mirror jigs, would be justified for a full CSP plant.
Blair, N.; Mehos, M.; Christensen, C.
2008-03-01
A comprehensive solar technology systems analysis model, the Solar Advisor Model (SAM) was developed to support the federal R&D community and the solar industry. This model, developed by staff at NREL and Sandia National Laboratory, is able to model the costs, finances, and performance of concentrating solar power and photovoltaics (PV). Currently, parabolic troughs and concentrating PV are the two concentrating technologies modeled within the SAM environment.
Parabolic Trough Receiver Heat Loss Testing (Poster)
Price, H.; Netter, J.; Bingham, C.; Kutscher, C.; Burkholder, F.; Brandemuehl, M.
2007-03-01
Parabolic trough receivers, or heat collection elements (HCEs), absorb sunlight focused by the mirrors and transfer that thermal energy to a fluid flowing within them. Thje absorbing tube of these receivers typically operates around 400 C (752 F). HCE manufacturers prevent thermal loss from the absorbing tube to the environment by using sputtered selective Cermet coatings on the absorber and by surrounding the absorber with a glass-enclosed evacuated annulus. This work quantifies the heat loss of the Solel UVAC2 and Schott PTR70 HCEs. At 400 C, the HCEs perform similarly, losing about 400 W/m of HCE length. To put this in perspective, the incident beam radiation on a 5 m mirror aperture is about 4500 W/m, with about 75% of that energy ({approx} 3400 W/m) reaching the absorber surface. Of the 3400 W/m on the absorber, about 3000 W/m is absorbed into the working fluid while 400 W/m is lost to the environment.
Photon-Atom Coupling with Parabolic Mirrors
Markus Sondermann; Gerd Leuchs
2015-07-23
Efficient coupling of light to single atomic systems has gained considerable attention over the past decades. This development is driven by the continuous growth of quantum technologies. The efficient coupling of light and matter is an enabling technology for quantum information processing and quantum communication. And indeed, in recent years much progress has been made in this direction. But applications aside, the interaction of photons and atoms is a fundamental physics problem. There are various possibilities for making this interaction more efficient, among them the apparently 'natural' attempt of mode-matching the light field to the free-space emission pattern of the atomic system of interest. Here we will describe the necessary steps of implementing this mode-matching with the ultimate aim of reaching unit coupling efficiency. We describe the use of deep parabolic mirrors as the central optical element of a free-space coupling scheme, covering the preparation of suitable modes of the field incident onto these mirrors as well as the location of an atom at the mirror's focus. Furthermore, we establish a robust method for determining the efficiency of the photon-atom coupling.
Bennett, Charles L.
2007-09-18
A solar thermal powered aircraft powered by heat energy from the sun. A heat engine, such as a Stirling engine, is carried by the aircraft body for producing power for a propulsion mechanism, such as a propeller. The heat engine has a thermal battery in thermal contact with it so that heat is supplied from the thermal battery. A solar concentrator, such as reflective parabolic trough, is movably connected to an optically transparent section of the aircraft body for receiving and concentrating solar energy from within the aircraft. Concentrated solar energy is collected by a heat collection and transport conduit, and heat transported to the thermal battery. A solar tracker includes a heliostat for determining optimal alignment with the sun, and a drive motor actuating the solar concentrator into optimal alignment with the sun based on a determination by the heliostat.
Lightweight, low-cost solar energy collector
NASA Technical Reports Server (NTRS)
Hochberg, Eric B. (Inventor); Costen, Michael K. (Inventor)
2006-01-01
A lightweight solar concentrator of the reflecting parabolic or trough type is realized via a thin reflecting film, an inflatable structural housing and tensioned fibers. The reflector element itself is a thin, flexible, specularly-reflecting sheet or film. The film is maintained in the parabolic trough shape by means of a plurality of identical tensioned fibers arranged to be parallel to the longitudinal axis of the parabola. Fiber ends are terminated in two identical spaced anchorplates, each containing a plurality of holes which lie on the desired parabolic contour. In a preferred embodiment, these fibers are arrayed in pairs with one fiber contacting the front side of the reflecting film and the other contacting the back side of the reflecting film. The reflective surface is thereby slidably captured between arrays of fibers which control the shape and position of the reflective film. Gas pressure in the inflatable housing generates fiber tension to achieve a truer parabolic shape.
Orientation mount for a solar heating module
Lhenry, B.
1984-07-10
The present invention relates to an elevation orientation mount for a parabolic mirror reflector of a solar heating module. The altazimuthal orientation mount according to the invention is adapted to a solar heating module comprising a parabolic mirror reflector orientable around a horizontal axis by a jack actuating unit whose cylinder is a turret and whose rod is articulated to the reflector. The jack is equipped for return and locking tending to extend the rod and to lock it at the stroke-end where the reflector occupies a position such that its axis of revolution is vertical.
Modular solar food dryers for farm use
Wagner, C.J. Jr.; Coleman, R.L.; Berry, R.E.
1981-01-01
Several solar food dryer modules have been constructed. Their design has been based on a low-cost, small-scale solar dryer using a unique parabolic reflector construction to increase radiation on the drying surface. Each module has a drying surface of 1.1 M/sup 2/ and a parabolic reflector area of 3.3 M/sup 2/. Some modules are being used to dry mango slices (a potential new food product) for market testing, while others are used for experiments to improve drying efficiency. A description is given of the operating conditions of the modules drying mango slices and the most effective modifications.
Surface Error Estimation of Pseudo-ParabolicSurface Made by Using Gore Membranes
NASA Astrophysics Data System (ADS)
Nagata, Tomoko; Ishida, Ryohei
In this paper, we describe the surface error of pseudo-parabolic surface, to construct an inflatable parabolic reflector. The gore sheet is generated by cutting the three-dimensional parabolic surface. A scheme of generating the gore sheet is described, and the rms surface error between the parabolic surface and the three-dimensional shape composed of the gore sheets is proposed and formulated. The rms surface error between the parabolic surface and the shape produced by pressurizing the circular membrane is also formulated. Finally, the possibility that the parabolic reflector composed of the gore sheets has high surface accuracy is shown.
Existence and dynamics of quasilinear parabolic systems with time delays
NASA Astrophysics Data System (ADS)
Pao, C. V.; Ruan, W. H.
2015-05-01
This paper is concerned with a coupled system of quasilinear parabolic equations where the effect of time delays is taken into consideration in the reaction functions of the system. The partial differential operators in the system may be degenerate and the reaction functions possess some mixed quasimonotone property, including quasimonotone nondecreasing functions. The aim of the paper is to show the existence and uniqueness of a global solution to the parabolic system, the existence of positive quasisolutions or maximal-minimal solutions of the corresponding elliptic system, and the asymptotic behavior of the solution of the parabolic system in relation to the quasisolutions or maximal-minimal solutions of the elliptic system. Applications are given to three reaction-diffusion models arising from mathematical biology and ecology where the diffusion coefficients are density dependent and are degenerate. This degenerate density-dependent diffusion leads to some interesting distinct asymptotic behavior of the time-dependent solution when compared with density-independent diffusion.
Numerical performance of the parabolized ADM formulation of general relativity
Paschalidis, Vasileios; Hansen, Jakob; Khokhlov, Alexei
2008-09-15
In a recent paper [Vasileios Paschalidis, Phys. Rev. D 78, 024002 (2008).], the first coauthor presented a new parabolic extension (PADM) of the standard 3+1 Arnowitt, Deser, Misner (ADM) formulation of the equations of general relativity. By parabolizing first-order ADM in a certain way, the PADM formulation turns it into a well-posed system which resembles the structure of mixed hyperbolic-second-order parabolic partial differential equations. The surface of constraints of PADM becomes a local attractor for all solutions and all possible well-posed gauge conditions. This paper describes a numerical implementation of PADM and studies its accuracy and stability in a series of standard numerical tests. Numerical properties of PADM are compared with those of standard ADM and its hyperbolic Kidder, Scheel, Teukolsky (KST) extension. The PADM scheme is numerically stable, convergent, and second-order accurate. The new formulation has better control of the constraint-violating modes than ADM and KST.
A Smooth Regularization of the Projection Formula for Constrained Parabolic Optimal Control Problems
Nabben, Reinhard
A Smooth Regularization of the Projection Formula for Constrained Parabolic Optimal Control parabolic optimal control problems. We summarize the optimality conditions in function spaces numerical results for an example problem. 1 Introduction Optimal control problems (OCPs) subject to time
Property estimation using inverse methods for elliptic and parabolic partial differential equations
Parmekar, Sandeep
1994-01-01
In this work we use inverse methods to estimate flow coefficients in both elliptic and parabolic partial differential equations. An algorithm is developed to solve a one layer problem for elliptic and parabolic partial differential equations...
Operational Experience from Solar Thermal Energy Projects
NASA Technical Reports Server (NTRS)
Cameron, C. P.
1984-01-01
Over the past few years, Sandia National Laboratories were involved in the design, construction, and operation of a number of DOE-sponsored solar thermal energy systems. Among the systems currently in operation are several industrial process heat projects and the Modular Industrial Solar Retrofit qualification test systems, all of which use parabolic troughs, and the Shenandoah Total Energy Project, which uses parabolic dishes. Operational experience has provided insight to both desirable and undesirable features of the designs of these systems. Features of these systems which are also relevant to the design of parabolic concentrator thermal electric systems are discussed. Other design features discussed are system control functions which were found to be especially convenient or effective, such as local concentrator controls, rainwash controls, and system response to changing isolation. Drive systems are also discussed with particular emphasis of the need for reliability and the usefulness of a manual drive capability.
Global Attractor for a Parabolic-Hyperbolic Penrose-Fife Phase Field System
Rocca, Elisabetta
Global Attractor for a Parabolic-Hyperbolic Penrose-Fife Phase Field System Elisabetta Rocca is governed by a parabolic singular equation coming from the Penrose-Fife theory) and the order parameter: Penrose-Fife model, parabolic-hyperbolic system, dissipativity, glo- bal attractor. AMS (MOS) subject
Current and Future Costs for Parabolic Trough and Power Tower Systems in the US Market: Preprint
Turchi, C.; Mehos, M.; Ho, C. K.; Kolb, G. J.
2010-10-01
NREL's Solar Advisor Model (SAM) is employed to estimate the current and future costs for parabolic trough and molten salt power towers in the US market. Future troughs are assumed to achieve higher field temperatures via the successful deployment of low melting-point, molten-salt heat transfer fluids by 2015-2020. Similarly, it is assumed that molten salt power towers are successfully deployed at 100MW scale over the same time period, increasing to 200MW by 2025. The levelized cost of electricity for both technologies is predicted to drop below 11 cents/kWh (assuming a 10% investment tax credit and other financial inputs outlined in the paper), making the technologies competitive in the marketplace as benchmarked by the California MPR. Both technologies can be deployed with large amounts of thermal energy storage, yielding capacity factors as high as 65% while maintaining an optimum LCOE.
Current and future costs for parabolic trough and power tower systems in the US market.
Turchi, Craig; Kolb, Gregory J.; Mehos, Mark Steven; Ho, Clifford Kuofei
2010-08-01
NREL's Solar Advisor Model (SAM) is employed to estimate the current and future costs for parabolic trough and molten salt power towers in the US market. Future troughs are assumed to achieve higher field temperatures via the successful deployment of low melting-point, molten-salt heat transfer fluids by 2015-2020. Similarly, it is assumed that molten salt power towers are successfully deployed at 100MW scale over the same time period, increasing to 200MW by 2025. The levelized cost of electricity for both technologies is predicted to drop below 11 cents/kWh (assuming a 10% investment tax credit and other financial inputs outlined in the paper), making the technologies competitive in the marketplace as benchmarked by the California MPR. Both technologies can be deployed with large amounts of thermal energy storage, yielding capacity factors as high as 65% while maintaining an optimum LCOE.
Dynamical constants of structured photons with parabolic-cylindrical symmetry
B. M. Rodriguez-Lara; R. Jauregui
2009-05-20
Electromagnetic modes with parabolic-cylindrical symmetry and their dynamical variables are studied both in the classical and quantum realm. As a result, a new dynamical constant for the electromagnetic field is identified and linked to the symmetry operator which supports it.
EPIC: A New and Advanced Nonlinear Parabolized Stability Equation Solver
Oliviero, Nick B
2015-05-14
, and verification of EPIC. EPIC is a new Nonlinear Parabolized Stability Equation (NPSE) solver developed in-house in our Computational Stability and Transition (CST) lab that will aid in the study, understanding, and prediction of laminar-to-turbulent boundary...
Teaching Parabolic Motion with Stop-Action Animations*
Teaching Parabolic Motion with Stop-Action Animations* WILLIAM CHURCH1 , BRIAN GRAVEL2 and CHRIS reports and class tests, with variable success, to encourage the students to critically examine to encourage students to build a simulation of their experiment and test their model against experimental data
Anisotropic uniqueness classes for a degenerate parabolic equation
Vil'danova, V F; Mukminov, F Kh
2013-11-30
Anisotropic uniqueness classes of Tacklind type are identified for a degenerate linear parabolic equation of the second order in an unbounded domain. The Cauchy problem and mixed problems with boundary conditions of the first and third type are considered. Bibliography: 18 titles.
The dynamics of parabolic flight: flight characteristics and passenger percepts
Karmali, Faisal; Shelhamer, Mark
2008-01-01
Flying a parabolic trajectory in an aircraft is one of the few ways to create freefall on Earth, which is important for astronaut training and scientific research. Here we review the physics underlying parabolic flight, explain the resulting flight dynamics, and describe several counterintuitive findings, which we corroborate using experimental data. Typically, the aircraft flies parabolic arcs that produce approximately 25 seconds of freefall (0 g) followed by 40 seconds of enhanced force (1.8 g), repeated 30–60 times. Although passengers perceive gravity to be zero, in actuality acceleration, and not gravity, has changed, and thus we caution against the terms "microgravity" and "zero gravity. " Despite the aircraft trajectory including large (45°) pitch-up and pitch-down attitudes, the occupants experience a net force perpendicular to the floor of the aircraft. This is because the aircraft generates appropriate lift and thrust to produce the desired vertical and longitudinal accelerations, respectively, although we measured moderate (0.2 g) aft-ward accelerations during certain parts of these trajectories. Aircraft pitch rotation (average 3°/s) is barely detectable by the vestibular system, but could influence some physics experiments. Investigators should consider such details in the planning, analysis, and interpretation of parabolic-flight experiments. PMID:19727328
Orthostatic Intolerance and Motion Sickness After Parabolic Flight
NASA Technical Reports Server (NTRS)
Schlegel, Todd T.; Brown, Troy E.; Wood, Scott J.; Benavides, Edgar W.; Bondar, Roberta L.; Stein, Flo; Moradshahi, Peyman; Harm, Deborah L.; Low, Phillip A.
1999-01-01
Orthostatic intolerance is common in astronauts after prolonged space flight. However, the "push-pull effect" in military aviators suggests that brief exposures to transitions between hypo- and hypergravity are sufficient to induce untoward autonomic cardiovascular physiology in susceptible individuals. We therefore investigated orthostatic tolerance and autonomic cardiovascular function in 16 healthy test subjects before and after a seated 2-hr parabolic flight. At the same time, we also investigated relationships between parabolic flight-induced vomiting and changes in orthostatic and autonomic cardiovascular function. After parabolic flight, 8 of 16 subjects could not tolerate a 30-min upright tilt test, compared to 2 of 16 before flight. Whereas new intolerance in non-Vomiters resembled the clinical postural tachycardia syndrome (POTS), new intolerance in Vomiters was characterized by comparatively isolated upright hypocapnia and cerebral vasoconstriction. As a group, Vomiters also had evidence for increased postflight fluctuations in efferent vagal-cardiac nerve traffic occurring independently of any superimposed change in respiration. Results suggest that syndromes of orthostatic intolerance resembling those occurring after space flight can occur after a brief (i.e., 2-hr) parabolic flight.
Upwind Algorithm For Parabolized Navier-Stokes Equations
NASA Technical Reports Server (NTRS)
Lawrence, Scott L.; Chaussee, Denny S.; Tannehill, John C.
1990-01-01
Supersonic flow about cone calculated accurately. Report presents theoretical basis of computer code solving parabolized Navier-Stokes equations of supersonic and hypersonic flow. For increased accuracy in resolution of details of strong aerodynamic shocks, code incorporates implicit, finite-volume, upwind numerical-integration scheme. Performs well in numerical simulations of flows around simple bodies.
KA-BROADBAND SATELLITE COMMUNICATION USING CYCLOSTATIONARY PARABOLIC BEAMFORMING
Blostein, Steven D.
KA-BROADBAND SATELLITE COMMUNICATION USING CYCLOSTATIONARY PARABOLIC BEAMFORMING by PAUL LUSINA for Military Satellite Communications : : : : : : : : 7 2.1.2 Performance of Contour Shaped Beam Antennas of a broadband satellite system which operates at the Ka frequency band. A channel model was developed which
Rothe's method for parabolic problems with nonlinear degenerating coefficient
Rothe's method for parabolic problems with nonlinear degenerating coefficient Volker Pluschke on the solution u. We approximate the problem by semidiscretization in time (Rothe's method) and prove uniform in time (Rothe's method). Here G ae R N , N â?? 2, denotes a simply connected, bounded domain with boundary
Bifurcations of normally parabolic tori in Hamiltonian systems
NASA Astrophysics Data System (ADS)
Broer, Henk W.; Hanßmann, Heinz; You, Jiangong
2005-07-01
We consider perturbations of integrable Hamiltonian systems in the neighbourhood of normally parabolic invariant tori. Under appropriate transversality conditions the tori in the unperturbed system bifurcate according to a (generalized) cuspoid catastrophe. Combining techniques of KAM theory and singularity theory, we show that such bifurcation scenarios survive the perturbation on large Cantor sets. Applications to rigid body dynamics and forced oscillators are pointed out.
Bifurcations of Normally Parabolic Tori in Hamiltonian Systems
bifurcate according to a (generalized) cuspoid catastrophe. Combining techniques of KAMBifurcations of Normally Parabolic Tori in Hamiltonian Systems Henk W. Broer Instituut voor{theory and singularity theory we show that such bifurcation scenarios survive the perturbation on large Cantor sets. Ap
NONLINEAR PARABOLIC CAPACITY AND POLAR SETS OF SUPERPARABOLIC FUNCTIONS
Kinnunen, Juha
to the underlying Sobolev space, but the situation is more del- icate for parabolic partial differential equations differential equation than to the underlying function space. As far as we are aware, this work is the first spaces. Droniou, Porretta and Prignet [10], as well as Saraiva [35], [36], also consider the nonquadratic
An Application of Calculus: Optimum Parabolic Path Problem
ERIC Educational Resources Information Center
Atasever, Merve; Pakdemirli, Mehmet; Yurtsever, Hasan Ali
2009-01-01
A practical and technological application of calculus problem is posed to motivate freshman students or junior high school students. A variable coefficient of friction is used in modelling air friction. The case in which the coefficient of friction is a decreasing function of altitude is considered. The optimum parabolic path for a flying object…
Optimal Design of Parabolic Canal Section Bhagu R. Chahar1
Chahar, B. R.
in a network may be either unlined or lined. River beds, unlined canals, and irrigation furrows all tend-Koopaei 2001 . A lined parabolic channel has no sharp angles of stress concentration where cracks may occur and other types of earth moving equipment Mironenko et al. 1984 . Irrigation canals are lined for several
Densities for Measures Associated with Parabolic IFS with Overlaps
Solomyak, Boris
Lq Densities for Measures Associated with Parabolic IFS with Overlaps BORIS SOLOMYAK & MARIUSZ URBA. Lyons [L] found a threshold parameter above which the measures cannot have a density in L2(R). We prove that this threshold is sharp by showing that the measures are absolutely continuous with a density in L2(R) for almost
Excited states in a parabolic trap Matthew Coles1
Pelinovsky, Dmitry
Excited states in a parabolic trap Matthew Coles1 , Dmitry Pelinovsky1 , and Panos Kevrekidis2 1.Pelinovsky (McMaster University) Excited states 1 / 28 #12;Introduction Introduction Density waves in cigar parameter. D.Pelinovsky (McMaster University) Excited states 2 / 28 #12;Introduction Ground state
Optimal boundary control of a system of semilinear parabolic equations
Nabben, Reinhard
controlled by d, which we want to neutralize with the other substance u controlled by c. In our examples, weOptimal boundary control of a system of semilinear parabolic equations WERNER BARTHEL, CHRISTIAN JOHN AND FREDI TRÖLTZSCH July 17, 2008 Abstract In this work, boundary control problems governed
IR Spectrometer Using 90-degree Off-axis Parabolic Mirrors
Robert M. Malone, Richard, G. Hacking, Ian J. McKenna, and Daniel H. Dolan
2008-09-02
A gated spectrometer has been designed for real-time, pulsed infrared (IR) studies at the National Synchrotron Light ource at the Brookhaven National Laboratory. A pair of 90-degree, off-axis parabolic mirrors are used to relay the light from an entrance slit to an output IR recording camera. With an initial wavelength range of 1500–4500 nm required, gratings could not be used in the spectrometer because grating orders would overlap. A magnesium oxide prism, placed between these parabolic mirrors, serves as the dispersion element. The spectrometer is doubly telecentric. With proper choice of the air spacing between the prism and the second parabolic mirror, any spectral region of interest within the InSb camera array’s sensitivity region can be recorded. The wavelengths leaving the second parabolic mirror are collimated, thereby relaxing the camera positioning tolerance. To set up the instrument, two different wavelength (visible) lasers are introduced at the entrance slit and made collinear with the optical axis via flip mirrors. After dispersion by the prism, these two laser beams are directed to tick marks located on the outside housing of the gated IR camera. This provides first-order wavelength calibration for the instrument. Light that is reflected off the front prism face is coupled into a high-speed detector to verify steady radiance during the gated spectral imaging. Alignment features include tick marks on the prism and parabolic mirrors. This instrument was designed to complement singlepoint pyrometry, which provides continuous time histories of a small collection of spots from shock-heated targets.
IR Spectrometer Using 90-Degree Off-Axis Parabolic Mirrors
Robert M. Malone, Ian J. McKenna
2008-03-01
A gated spectrometer has been designed for real-time, pulsed infrared (IR) studies at the National Synchrotron Light Source at the Brookhaven National Laboratory. A pair of 90-degree, off-axis parabolic mirrors are used to relay the light from an entrance slit to an output recording camera. With an initial wavelength range of 1500–4500 nm required, gratings could not be used in the spectrometer because grating orders would overlap. A magnesium oxide prism, placed between these parabolic mirrors, serves as the dispersion element. The spectrometer is doubly telecentric. With proper choice of the air spacing between the prism and the second parabolic mirror, any spectral region of interest within the InSb camera array’s sensitivity region can be recorded. The wavelengths leaving the second parabolic mirror are collimated, thereby relaxing the camera positioning tolerance. To set up the instrument, two different wavelength (visible) lasers are introduced at the entrance slit and made collinear with the optical axis via flip mirrors. After dispersion by the prism, these two laser beams are directed to tick marks located on the outside housing of the gated IR camera. This provides first-order wavelength calibration for the instrument. Light that is reflected off the front prism face is coupled into a high-speed detector to verify steady radiance during the gated spectral imaging. Alignment features include tick marks on the prism and parabolic mirrors. This instrument was designed to complement single-point pyrometry, which provides continuous time histories of a small collection of spots from shock-heated targets.
Electromagnetic Casimir forces of parabolic cylinder and knife-edge geometries
Graham, Noah; Shpunt, Alexander; Kardar, Mehran; Emig, Thorsten; Rahi, Sahand Jamal; Jaffe, Robert L.
2011-06-15
An exact calculation of electromagnetic scattering from a perfectly conducting parabolic cylinder is employed to compute Casimir forces in several configurations. These include interactions between a parabolic cylinder and a plane, two parabolic cylinders, and a parabolic cylinder and an ordinary cylinder. To elucidate the effect of boundaries, special attention is focused on the 'knife-edge' limit in which the parabolic cylinder becomes a half-plane. Geometrical effects are illustrated by considering arbitrary rotations of a parabolic cylinder around its focal axis, and arbitrary translations perpendicular to this axis. A quite different geometrical arrangement is explored for the case of an ordinary cylinder placed in the interior of a parabolic cylinder. All of these results extend simply to nonzero temperatures.
Acurex Parabolic Dish Concentrator (PDC-2)
NASA Technical Reports Server (NTRS)
Overly, P.; Bedard, R.
1982-01-01
The design approach, rationale for the selected configuration, and the development status of a cost effective point-focus solar concentrator are discussed. The low-cost concentrator reflective surface design is based on the use of a thin, backsilvered mirror glass reflector bonded to a molded structural plastic substrate. The foundation, support, and drive subassembles are described. A hybrid, two-axis, Sun tracking control system based on microprocessor technology was selected. Coarse synthetic tracking is achieved through a microcomputer-based control system to calculate Sun position for transient periods of cloud cover as well as sundown and sunrise positioning. Accurate active tracking is achieved by two-axis optical sensors. Results of the reflective panel demonstration tests investigating slope error, hail impact survivability, temperature/humidity cycling, longitudinal strength/bending stiffness, and torsional stiffness are discussed.
Shenandoah Solar Total-Energy Project
Leonard, J.A.; Hunke, R.W.
1982-12-01
The design and construction of the world's first solar total-energy plant in the private sector has been completed and checkout is underway. During its operational phase, the solar plant will furnish electrical power, process steam, and other thermal energy to a nearby knitwear factory. The solar system consists of a collector field containing 114 parabolic-dish collectors which supply thermal energy at 400/sup 0/C to drive a 400 kW multi-stage Rankine-cycle turbine generator. Some steam is extracted from the turbine and supplied to the knitwear manufacturing processes. The system will be grid-connected. Presented are: (1) a description of the system and components being installed; (2) a summary of performance testing of the extraction turbine and of four prototype parabolic-dish collectors; and (3) a discussion of design considerations and insights which have general applicability to solar-thermal-system designs.
Line-focus solar thermal energy technology development. FY 79 annual report for Department 4720
Bergeron, K D; Champion, R L; Hunke, R W
1980-04-01
The primary role of the Solar Energy Projects Department II (4720) is the development, evaluation, and testing of line-focus solar thermal technology. This report of FY 79 progress and accomplishments is divided into two parts: (1) Component and Subsystem Development including the design and analysis of collector modules, their components, and associated materials and processes, and (2) Systems and Applications Development, involving larger configurations of solar thermal line-focus systems. The emphasis is on parabolic troughs, but significant efforts on hemispherical bowls, compound parabolic collectors, and dishes for the Solar Total Energy Project are also described.
Air Brayton Solar Receiver, phase 1
NASA Technical Reports Server (NTRS)
Zimmerman, D. K.
1979-01-01
A six month analysis and conceptual design study of an open cycle Air Brayton Solar Receiver (ABSR) for use on a tracking, parabolic solar concentrator are discussed. The ABSR, which includes a buffer storage system, is designed to provide inlet air to a power conversion unit. Parametric analyses, conceptual design, interface requirements, and production cost estimates are described. The design features were optimized to yield a zero maintenance, low cost, high efficiency concept that will provide a 30 year operational life.
Environmental responses of solar reflective surfaces
NASA Technical Reports Server (NTRS)
Bouquet, F. L.
1983-01-01
An assessment is undertaken of the environmental responses of solar reflective surfaces, with emphasis on dish-type concentrator surfaces exposed to the conditions of Southern California. A generalized mathematical model for specific solar reflective surfaces can be formulated on the basis of either experimental or assumed site degradation/corrosion data. In addition, the fabrication parameters of a parabolic reflecting surface and its substrate can be used to model combined reflective characteristics for the postulated environmental conditions.
Harrison, T.D.
1981-04-01
Sandia National Laboratories, Albuquerque (SNLA), is currently conducting a program to predict the performance and measure the characteristics of commercially available solar collectors that have the potential for use in industrial process heat and enhanced oil recovery applications. The thermal performance predictions for the Solar Kinetics T-600 solar line-focusing parabolic trough collector are presented for three output temperatures at five cities in the US. (WHK)
Physiologic Pressure and Flow Changes During Parabolic Flight (Pilot Study)
NASA Technical Reports Server (NTRS)
Pantalos, George; Sharp, M. Keith; Mathias, John R.; Hargens, Alan R.; Watenpaugh, Donald E.; Buckey, Jay C.
1999-01-01
The objective of this study was to obtain measurement of cutaneous tissue perfusion central and peripheral venous pressure, and esophageal and abdominal pressure in human test subjects during parabolic flight. Hemodynamic data recorded during SLS-I and SLS-2 missions have resulted in the paradoxical finding of increased cardiac stroke volume in the presence of a decreased central venous pressure (CVP) following entry in weightlessness. The investigators have proposed that in the absence of gravity, acceleration-induced peripheral vascular compression is relieved, increasing peripheral vascular capacity and flow while reducing central and peripheral venous pressure, This pilot study seeks to measure blood pressure and flow in human test subjects during parabolic flight for different postures.
Development and testing of Parabolic Dish Concentrator No. 1
NASA Astrophysics Data System (ADS)
Dennison, E. W.; Thostesen, T. O.
1984-12-01
Parabolic Dish Concentrator No. 1 (PDC-1) is a 12-m-diameter prototype concentrator with low life-cycle costs for use with thermal-to-electric energy conversion devices. The concentrator assembly features panels made of a resin transfer molded balsa core/fiberglass sandwich with plastic reflective film as the reflective surface and a ribbed framework to hold the panels in place. The concentrator assembly tracks in azimuth and elevation on a base frame riding on a circular track. It is shown that the panels do not exhibit the proper parabolic contour. However, thermal gradients were discovered in the panels with daily temperature changes. The PDC-1 has sufficient optical quality to operate satisfactorily in a dish-electric system. The PDC-1 development provides the impetus for creating innovative optical testing methods and valuable information for use in designing and fabricating concentrators of future dish-electric systems.
Shock wave convergence in water with parabolic wall boundaries
Yanuka, D.; Shafer, D.; Krasik, Ya.
2015-04-28
The convergence of shock waves in water, where the cross section of the boundaries between which the shock wave propagates is either straight or parabolic, was studied. The shock wave was generated by underwater electrical explosions of planar Cu wire arrays using a high-current generator with a peak output current of ?45?kA and rise time of ?80?ns. The boundaries of the walls between which the shock wave propagates were symmetric along the z axis, which is defined by the direction of the exploding wires. It was shown that with walls having a parabolic cross section, the shock waves converge faster and the pressure in the vicinity of the line of convergence, calculated by two-dimensional hydrodynamic simulations coupled with the equations of state of water and copper, is also larger.
Development and testing of Parabolic Dish Concentrator No. 1
NASA Technical Reports Server (NTRS)
Dennison, E. W.; Thostesen, T. O.
1984-01-01
Parabolic Dish Concentrator No. 1 (PDC-1) is a 12-m-diameter prototype concentrator with low life-cycle costs for use with thermal-to-electric energy conversion devices. The concentrator assembly features panels made of a resin transfer molded balsa core/fiberglass sandwich with plastic reflective film as the reflective surface and a ribbed framework to hold the panels in place. The concentrator assembly tracks in azimuth and elevation on a base frame riding on a circular track. It is shown that the panels do not exhibit the proper parabolic contour. However, thermal gradients were discovered in the panels with daily temperature changes. The PDC-1 has sufficient optical quality to operate satisfactorily in a dish-electric system. The PDC-1 development provides the impetus for creating innovative optical testing methods and valuable information for use in designing and fabricating concentrators of future dish-electric systems.
Wide Range Detector Using Parabolic Cylindrical Mirror for THz Applications
NASA Astrophysics Data System (ADS)
Yasui, Takanari; Ohtsuka, Takeshi; Suzuki, Tetsu; Okajima, Shigeki; Nakayama, Kazuya; Tomioka, Mitsuru; Kamimura, Katsuhiro; Namekata, Takeo; Minamide, Hiroaki; Ito, Hiromasa
2006-02-01
A new, wide-band, high-speed and high-sensitivity THz detector has been developed. The prototype detector consists of a parabolic cylindrical mirror, a long wire antenna and a Schottky barrier diode. Direct detection measurements have shown a stable sensitivity of 150 ± 50 V/W for 1 2 THz without any adjustments. The long wire antenna was fixed at the focus of parabolic cylindrical mirror then it has been realized less operation steps, easy coupling to the external THz signals and a dramatic enhancement in the practicality of this system. The optically polished mirror and frosted surface one showed comparable sensitivities, thus easy polishing and less cost mirror fabrication can be applied for this system. The radiation pattern showed a maximum radiation angle of approximately 23° with its dominant main lobe, which was attributed to the wire antenna character and confirmed good agreements with classical antenna theory.
?-neighbourhoods of orbits of parabolic diffeomorphisms and cohomological equations
NASA Astrophysics Data System (ADS)
Resman, Maja
2014-12-01
In this article, we study the analyticity of (directed) areas of ?-neighbourhoods of orbits of parabolic germs. The article is motivated by the question of analytic classification using ?-neighbourhoods of orbits in the simplest formal class. We show that the coefficient in front of the ?2 term in the asymptotic expansion in ?, which we call the principal part of the area, is a sectorially analytic function in the initial point of the orbit. It satisfies a cohomological equation similar to the standard trivialization equation for parabolic diffeomorphisms. We give necessary and sufficient conditions on a diffeomorphism f for the existence of a globally analytic solution of this equation. Furthermore, we introduce a new classification type for diffeomorphisms implied by this new equation and investigate the relative position of its classes with respect to the analytic classes.
Discontinuous Galerkin Finite Element Method for Parabolic Problems
NASA Technical Reports Server (NTRS)
Kaneko, Hideaki; Bey, Kim S.; Hou, Gene J. W.
2004-01-01
In this paper, we develop a time and its corresponding spatial discretization scheme, based upon the assumption of a certain weak singularity of parallel ut(t) parallel Lz(omega) = parallel ut parallel2, for the discontinuous Galerkin finite element method for one-dimensional parabolic problems. Optimal convergence rates in both time and spatial variables are obtained. A discussion of automatic time-step control method is also included.
Parabolic fixed points and stability criteria for nonlinear Hill's equation
NASA Astrophysics Data System (ADS)
Núńez, D.; Ortega, R.
We discuss the stability of parabolic fixed points of area-preserving mappings and obtain a new proof of a criterion due to Simó. These results are employed to discuss the stability of the equilibrium of certain periodic differential equations of newtonian type. An example is the pendulum of variable length. In this class of equations the First Lyapunov's Method does not apply but in many cases the stability can be characterized in terms of the variational equation.
Real-time optical laboratory solution of parabolic differential equations
NASA Technical Reports Server (NTRS)
Casasent, David; Jackson, James
1988-01-01
An optical laboratory matrix-vector processor is used to solve parabolic differential equations (the transient diffusion equation with two space variables and time) by an explicit algorithm. This includes optical matrix-vector nonbase-2 encoded laboratory data, the combination of nonbase-2 and frequency-multiplexed data on such processors, a high-accuracy optical laboratory solution of a partial differential equation, new data partitioning techniques, and a discussion of a multiprocessor optical matrix-vector architecture.
On the Morse complex for semilinear parabolic equations
NASA Astrophysics Data System (ADS)
Jänig, A.
2015-08-01
A Morse-Smale function on a compact Riemannian manifold can be used to define an associated Morse complex. Its homology is isomorphic to the singular homology of the manifold, which coincides with the singular homology of the Conley index of the manifold. In this paper, we consider an analogous Morse complex for isolated invariant sets of certain semilinear parabolic equations. It is shown that its homology is isomorphic to the singular homology of the Conley index of the isolated invariant set.
Radiative Heat Transfer During Atmosphere Entry at Parabolic Velocity
NASA Technical Reports Server (NTRS)
Yoshikawa, Kenneth K.; Wick, Bradford H.
1961-01-01
Stagnation point radiative heating rates for manned vehicles entering the earth's atmosphere at parabolic velocity are presented and compared with corresponding laminar convective heating rates. The calculations were made for both nonlifting and lifting entry trajectories for vehicles of varying nose radius, weight-to-area ratio, and drag. It is concluded from the results presented that radiative heating will be important for the entry conditions considered.
A stability analysis for a semilinear parabolic partial differential equation
NASA Technical Reports Server (NTRS)
Chafee, N.
1973-01-01
The parabolic partial differential equation considered is u sub t = u sub xx + f(u), where minus infinity x plus infinity and o t plus infinity. Under suitable hypotheses pertaining to f, a class of initial data is exhibited: phi(x), minus infinity x plus infinity, for which the corresponding solutions u(x,t) appraoch zero as t approaches the limit of plus infinity. This convergence is uniform with respect to x on any compact subinterval of the real axis.
Gradient estimates for parabolic and elliptic systems from linear laminates
Hongjie Dong
2012-01-24
We establish several gradient estimates for second-order divergence type parabolic and elliptic systems. The coefficients and data are assumed to be H\\"older or Dini continuous in the time variable and all but one spatial variables. This type of systems arises from the problems of linearly elastic laminates and composite materials. For the proof, we use Campanato's approach in a novel way. Non-divergence type equations under a similar condition are also discussed.
Singular parabolic equations of second order on manifolds with singularities
NASA Astrophysics Data System (ADS)
Shao, Yuanzhen
2016-01-01
The main aim of this article is to establish an Lp-theory for elliptic operators on manifolds with singularities. The particular class of differential operators discussed herein may exhibit degenerate or singular behavior near the singular ends of the manifolds. Such a theory is of importance for the study of elliptic and parabolic equations on non-compact, or even incomplete manifolds, with or without boundary.
REGULARITY OF A FREE BOUNDARY IN PARABOLIC POTENTIAL ...
2002-11-03
that the functions (?eu)± are sub-caloric; we leave this to the reader. Then, for ..... In fact, we claim that for any parabolic cylinder Qr (x, t), not necessarily centered at a point on ..... Consider the family of continuous functions ?r defined on Q?(x0, t0) ? ? for every r > 0 ...... Then varying e and ? we obtain that the ratios. ?i u.
Galerkin/Runge-Kutta discretizations for semilinear parabolic equations
NASA Technical Reports Server (NTRS)
Keeling, Stephen L.
1987-01-01
A new class of fully discrete Galerkin/Runge-Kutta methods is constructed and analyzed for semilinear parabolic initial boundary value problems. Unlike any classical counterpart, this class offers arbitrarily high, optimal order convergence. In support of this claim, error estimates are proved, and computational results are presented. Furthermore, it is noted that special Runge-Kutta methods allow computations to be performed in parallel so that the final execution time can be reduced to that of a low order method.
Asymptotic behaviour of solutions of semilinear parabolic equations
Egorov, Yu V; Kondratiev, V A
2008-04-30
The asymptotic behaviour of solutions of a second-order semilinear parabolic equation is analyzed in a cylindrical domain that is bounded in the space variables. The dominant term of the asymptotic expansion of the solution as t{yields}+{infinity} is found. It is shown that the solution of this problem is asymptotically equivalent to the solution of a certain non-linear ordinary differential equation. Bibliography: 8 titles.
A parabolic mirror-based proximally actuated photoacoustic endoscope
NASA Astrophysics Data System (ADS)
Li, Chiye; Yang, Joon-Mo; Chen, Ruimin; Maslov, Konstantin; Zhou, Qifa; Shung, K. Kirk; Wang, Lihong V.
2013-03-01
We have developed a new photoacoustic endoscopic probe specifically designed for human urogenital imaging. The endoscopic probe uses a parabolic mirror-based mechanical scanning mechanism, providing an angular field of view of 270°. And it has a rigid, dome shaped end section for smooth cavity introduction. Here we introduce the new endoscope's design and imaging principle, and present experimental results validating its in vivo imaging ability.
Circulatory filling pressures during transient microgravity induced by parabolic flight
NASA Technical Reports Server (NTRS)
Latham, Ricky D.; Fanton, John W.; White, C. D.; Vernalis, Mariana N.; Crisman, R. P.; Koenig, S. C.
1993-01-01
Theoretical concepts hold that blood in the gravity dependent portion of the body would relocate to more cephalad compartments under microgravity. The result is an increase in blood volume in the thoraic and cardiac chambers. However, experimental data has been somewhat contradictory and nonconclusive. Early studies of peripheral venous pressure and estimates of central venous pressure (CVP) from these data did not show an increase in CVP under microgravity. However, CVP recorded in human volunteers during a parabolic flight revealed an increase in CVP during the microgravity state. On the STS 40 shuttle mission, a payload specialist wore a fluid line that recorded CVP during the first few hours of orbital insertion. These data revealed decreased CVP. When this CVP catheter was tested during parabolic flight in four subjects, two had increased CVP recordings and two had decreased CVP measurements. In 1991, our laboratory performed parabolic flight studies in several chronic-instrumented baboons. It was again noted that centrally recorded right atrial pressure varied with exposure to microgravity, some animals having an increase, and others a decrease.
Generalized Second Law of Thermodynamics in Parabolic LTB Inhomogeneous Cosmology
NASA Astrophysics Data System (ADS)
Sheykhi, A.; Moradpour, H.; K. Rezazadeh, Sarab; B., Wang
2015-11-01
We study thermodynamics of the parabolic Lemaitre–Tolman–Bondi (LTB) cosmology supported by a perfect fluid source. This model is the natural generalization of the flat Friedmann–Robertson–Walker (FRW) universe, and describes an inhomogeneous universe with spherical symmetry. After reviewing some basic equations in the parabolic LTB cosmology, we obtain a relation for the deceleration parameter in this model. We also obtain a condition for which the universe undergoes an accelerating phase at the present time. We use the first law of thermodynamics on the apparent horizon together with the Einstein field equations to get a relation for the apparent horizon entropy in LTB cosmology. We find out that in LTB model of cosmology, the apparent horizon's entropy could be feeded by a term, which incorporates the effects of the inhomogeneity. We consider this result and get a relation for the total entropy evolution, which is used to examine the generalized second law of thermodynamics for an accelerating universe. We also verify the validity of the second law and the generalized second law of thermodynamics for a universe filled with some kinds of matters bounded by the event horizon in the framework of the parabolic LTB model. Supported financially by Research Institute for Astronomy & Astrophysics of Maragha (RIAAM), Iran
Build an oven, cook a meal: How solar energy empowered women in Costa Rica
Blankenship, J. )
1990-12-01
A pilot solar cooking project in the hot, northern province of Guanacaste promises to serve as a model for community groups wanting to build their own solar ovens. An $8,000 (US) grant has been awarded by the Canadian Embassy in Costa Rica to take the Guanacaste project into a second stage in 1990-91. Two construction workshops, with twelve participants in each, are planned in communities near Oriente. Three women from the Oriente group will have paid jobs as organizational facilitators and workshop supervisors. In popular education this is called the multiplier effect - the users of solar cookers construct the ovens themselves, and then instruct others to do the same. 3 refs.
NASA Astrophysics Data System (ADS)
Dupraz, K.; Cassou, K.; Martens, A.; Zomer, F.
2015-10-01
The ABCD matrix for parabolic reflectors is derived for any incident angles. It is used in numerical studies of four-mirror cavities composed of two flat and two parabolic mirrors. Constraints related to laser beam injection efficiency, optical stability, cavity-mode, beam-waist size and high stacking power are satisfied. A dedicated alignment procedure leading to stigmatic cavity-modes is employed to overcome issues related to the optical alignment of parabolic reflectors.
Domestic Material Content in Molten-Salt Concentrating Solar Power Plants
Turchi, Craig; Kurup, Parthiv; Akar, Sertac; Flores, Francisco
2015-08-26
This study lists material composition data for two concentrating solar power (CSP) plant designs: a molten-salt power tower and a hypothetical parabolic trough plant, both of which employ a molten salt for the heat transfer fluid (HTF) and thermal storage media. The two designs have equivalent generating and thermal energy storage capacities. The material content of the saltHTF trough plant was approximately 25% lower than a comparably sized conventional oil-HTF parabolic trough plant. The significant reduction in oil, salt, metal, and insulation mass by switching to a salt-HTF design is expected to reduce the capital cost and LCOE for the parabolic trough system.
Research and Development of a Low Cost Solar Collector
Ansari, Asif; Philip, Lee; Thouppuarachchi, Chirath
2012-08-01
This is a Final Technical Report on the Research and Development completed towards the development of a Low Cost Solar Collector conducted under the DOE cost-sharing award EE-0003591. The objective of this project was to develop a new class of solar concentrators with geometries and manufacturability that could significantly reduce the fully installed cost of the solar collector field for concentrated solar thermal power plants. The goal of the project was to achieve an aggressive cost target of $170/m2, a reduction of up to 50% in the total installed cost of a solar collector field as measured against the current industry benchmark of a conventional parabolic trough. The project plan, and the detailed activities conducted under the scope of the DOE Award project addressed all major drivers that affect solar collector costs. In addition to costs, the study also focused on evaluating technical performance of new collector architectures and compared them to the performance of the industry benchmark parabolic trough. The most notable accomplishment of this DOE award was the delivery of a full-scale integrated design, manufacturing and field installation solution for a new class of solar collector architecture which has been classified as the Bi-Planar Fresnel Collector (BPFC) and may be considered as a viable alternative to the conventional parabolic trough, as well as the conventional Fresnel collectors. This was in part accomplished through the design and development, all the way through fabrication and test validation of a new class of Linear Planar Fresnel Collector architecture. This architecture offers a number of key differentiating features which include a planar light-weight frame geometry with small mass-manufacturable elements utilizing flat mirror sections. The designs shows significant promise in reducing the material costs, fabrication costs, shipping costs, and on-site field installation costs compared to the benchmark parabolic trough, as well as the conventional Fresnel collector. The noteworthy design features of the BPFC architecture include the use of relatively cheaper flat mirrors and a design which allows the mirror support beam sections to act as load-bearing structural elements resulting in more than a 36% reduction in the overall structural weight compared to an optimized parabolic trough. Also, it was shown that the utilization of small mass-produced elements significantly lowers mass-production and logistics costs that can more quickly deliver economies of scale, even for smaller installations while also reducing shipping and installation costs. Moreover, unlike the traditional Fresnel trough the BPFC architecture does not require complex articulating drive mechanisms but instead utilizes a standard parabolic trough hydraulic drive mechanism. In addition to the development of the Bi-Planar Fresnel Collector, an optimized conventional space-frame type parabolic trough was also designed, built, analyzed and field-tested during the first phase of this award. The design of the conventional space-frame parabolic collector was refined with extensive FEA and CFD analysis to reduce material costs and re-designed for simpler fabrication and more accurate lower-cost field assembly. This optimized parabolic trough represented an improvement over the state-of-the art of the traditional parabolic trough architecture and also served as a more rigorous and less subjective benchmark that was used for comparison of new candidate design architectures. The results of the expanded 1st phase of the DOE award project showed that both the Optimized Parabolic Trough and the new Bi-Planar Fresnel Collector design concepts failed to meet the primary objectives for the project of achieving a 50% cost reduction from the industry reference total installed cost of $350/m2. Results showed that the BPFC came in at projected total installed cost of $237/m2 representing a 32% savings compared to the industry benchmark conventional parabolic trough. And the cost reduction obtained by the Optimized Parabolic Trough compared to the
Solar economy and technology update
Brotherton, T.K.
1983-06-01
The industry, national, and consumer perspectives on solar power are reviewed. With a 30% increase in dealer/installers, and a 30% attrition rate, about 60% of the participants in the market are ''new kids on the block.'' The installed value of the market was $750 million in 1981. There was a 30% decline in volumes, due to the recession, in 1982. As for the national perspective, solar is labor intensive, and generated a billion dollars worth of jobs. As the DOE has abandoned all but high risk ''core technology'' RandD has faltered some. But desiccant heat pumps, polymer collectors, and parabolic collectors are discussed.
Invariant sets for discontinuous parabolic area-preserving torus maps
Peter Ashwin; Xin-Chu Fu; Takashi Nishikawa; Karol Zyczkowski
2000-01-04
We analyze a class of piecewise linear parabolic maps on the torus, namely those obtained by considering a linear map with double eigenvalue one and taking modulo one in each component. We show that within this two parameter family of maps, the set of noninvertible maps is open and dense. For cases where the entries in the matrix are rational we show that the maximal invariant set has positive Lebesgue measure and we give bounds on the measure. For several examples we find expressions for the measure of the invariant set but we leave open the question as to whether there are parameters for which this measure is zero.
Digital Foucault tester for the measurement of parabolic wave form
NASA Astrophysics Data System (ADS)
Wang, Xiao-peng; Zhu, Ri-hong; Wang, Lei
2009-07-01
Digital Foucault tester for quantitative estimate the wave form of aspheric surfaces is based on the high precision knife position determination and the image data processing methods. In this paper, we report a set of digital Foucault tester for the measurement of parabolic surface. The movement of the knife-edge is controlled by PC, and the shadow patterns are captured by a CCD in real time and then are fed back to the computer. A new kind of data processing method, which has the advantage of simple arithmetic and high precision, is given in the paper. The method offers a reliable base for Digital Foucault tester.
A finite volume scheme for nonlinear degenerate parabolic equations
Bessemoulin-Chatard, Marianne
2011-01-01
We propose a second order finite volume scheme for nonlinear degenerate parabolic equations. For some of these models (porous media equation, drift-diffusion system for semiconductors, ...) it has been proved that the transient solution converges to a steady-state when time goes to infinity. The present scheme preserves steady-states and provides a satisfying long-time behavior. Moreover, it remains valid and second-order accurate in space even in the degenerate case. After describing the numerical scheme, we present several numerical results which confirm the high-order accuracy in various regime degenerate and non degenerate cases and underline the efficiency to preserve the large-time asymptotic.
Fuzzy control of parabolic antenna with backlash compensation
NASA Astrophysics Data System (ADS)
Ahmed, Mohammed; Noor, Samsul Bahari B. Mohd
2015-05-01
A fuzzy logic based controller (FLC) was proposed for position control of a parabolic dish antenna system with the major aim of eradicating the effect backlash disturbance which may be present in the system. The disturbance is nonlinear and is capable of generating steady state positional errors. Simulation results obtained using SIMULINK/MATLAB 2012a were compared with those obtained when the controller was proportional-derivative controller (PDC). The fuzzy controller portrays that it has the capability of reducing the noise due to backlash and possibly others more than the proportional-derivative controller.
Piecewise-parabolic methods for astrophysical fluid dynamics
Woodward, P.R.
1983-11-01
A general description of some modern numerical techniques for the simulation of astrophysical fluid flow is presented. The methods are introduced with a thorough discussion of the especially simple case of advection. Attention is focused on the piecewise-parabolic method (PPM). A description of the SLIC method for treating multifluid problems is also given. The discussion is illustrated by a number of advection and hydrodynamics test problems. Finally, a study of Kelvin-Helmholtz instability of supersonic jets using PPM with SLIC fluid interfaces is presented.
Parabolized Navier-Stokes methods for hypersonic flows
NASA Astrophysics Data System (ADS)
Lawrence, Scott L.
A representative sampling of the techniques used in the integration of the Parabolized Navier-Stokes (PNS) equations is presented. Special atention is given to recent algorithms developed specifically for application to high speed flows, characterized by the presence of strong embedded shock waves and real gas effects. It is shown that PNS solvers are being used in the analysis of sonic boom signatures. Methods for modeling physical effects are discussed, including an overview of commonly used turbulence models and a more detailed discussion of techniques for including equilibrium and finite rate real gas effects.
Intrinsic formation of electromagnetic divergence and rotation by parabolic focusing
NASA Astrophysics Data System (ADS)
Shibata, Kazunori; Takai, Mayuko; Uemoto, Mitsuharu; Watanabe, Shinichi
2015-11-01
A linearly polarized electromagnetic wave is found to form divergent and rotation fields after focused by an off-axis parabolic mirror. These distributions are generated within a subwavelength scale around the focus and at times when the electric field at the focus vanishes. We theoretically and experimentally show that not only the direction but also the structure of the distributions varies with the incident polarization. In addition, the distributions move in one direction with a phase velocity faster than the speed of light.
Impurity binding energies in quantum dots with parabolic confinement
NASA Astrophysics Data System (ADS)
Abramov, Arnold
2015-03-01
We present an effective numerical procedure to calculate the binding energies and wave functions of the hydrogen-like impurity states in a quantum dot (QD) with parabolic confinement. The unknown wave function was expressed as an expansion over one-dimensional harmonic oscillator states, which describes the electron's movement along the defined z-axis. Green's function technique used to obtain the solution of Schredinger equation for electronic states in a transverse plane. Binding energy of impurity states is defined as poles of the wave function. The dependences of the binding energy on the position of an impurity, the size of the QD and the magnetic field strength are presented and discussed.
Inhomogeneous parabolic equations on unbounded metric measure spaces
Kenneth J. Falconer; Jiaxin Hu; Yuhua Sun
2011-03-29
We study inhomogeneous semilinear parabolic equations with source term f independent of time u_{t}={\\Delta}u+u^{p}+f(x) on a metric measure space, subject to the conditions that f(x)\\geq 0 and u(0,x)=\\phi(x)\\geq 0. By establishing Harnack-type inequalities in time t and some powerful estimates, we give sufficient conditions for non-existence, local existence, and global existence of weak solutions. This paper generalizes previous results on Euclidean spaces to general metric measure spaces.
Degtyarev, Sergey P
2010-09-02
The first initial-boundary problem for second-order parabolic and degenerate parabolic equations is investigated in a domain with a conical or angular point. The means of attack is already known and uses weighted classes of smooth or integrable functions. Sufficient conditions for a unique solution to exist and for coercive estimates for the solution to be obtained are formulated in terms of the angular measure of the solid angle and the exponent of the weight. It is also shown that if these conditions fail to hold, then the parabolic problem has elliptic properties, that is, it can have a nonzero kernel or can be nonsolvable, and, in the latter case, it is not even a Fredholm problem. A parabolic equation and an equation with some degeneracy or a singularity at a conical point are considered. Bibliography: 49 titles.
Weak solutions to a parabolic nonlinear system arising in biological dynamic in the soil
Frey, Pascal
Weak solutions to a parabolic nonlinear system arising in biological dynamic in the soil Come Sy. Abstract. We study a nonlinear parabolic system governing the biological dynamic in the soil. We57, 35B50, 35A15. 1. Introduction Biological dynamic in the soil is modeled by reaction
Bath Institute for Complex Systems Decay at infinity for parabolic equations
Scheichl, Robert
BICS Bath Institute for Complex Systems Decay at infinity for parabolic equations Oliver C. Schn://www.bath.ac.uk/math-sci/BICS #12;#12;DECAY AT INFINITY FOR PARABOLIC EQUATIONS OLIVER C. SCHN Â¨URER AND HARTMUT R. SCHWETLICK infinity. For a class of advection-diffusion equations with a spa- tially dependent velocity field, we
ANALYSIS OF A PARABOLIC CROSS-DIFFUSION POPULATION MODEL WITHOUT SELF-DIFFUSION
Jüngel, Ansgar
equations, strong cross-diffusion, weak competition, relative en- tropy, global-in-time existence of weakANALYSIS OF A PARABOLIC CROSS-DIFFUSION POPULATION MODEL WITHOUT SELF-DIFFUSION LI CHEN Institut f to a strongly coupled parabolic sys- tem arising in population dynamics is shown. The cross-diffusion terms
NASA Astrophysics Data System (ADS)
Dobrev, V. K.
2014-05-01
In the present paper we review the progress of the project of classification and construction of invariant differential operators for non-compact semisimple Lie groups. Our starting points is the class of algebras, which we called earlier 'conformal Lie algebras' (CLA), which have very similar properties to the conformal algebras of Minkowski space-time, though our aim is to go beyond this class in a natural way. For this we introduced recently the new notion of parabolic relation between two non-compact semisimple Lie algebras G and G' that have the same complexification and possess maximal parabolic subalgebras with the same complexification. Thus, we consider the exceptional algebra E7(7) which is parabolically related to the CLA E7(-25). Other interesting examples are the orthogonal algebras so(p, q) all of which are parabolically related to the conformal algebra so(n, 2) with p + q = n + 2, the parabolic subalgebras including the Lorentz subalgebra so(n - 1,1) and its analogs so(p - 1, q - 1). Further we consider the algebras sl(2n, Bbb R) and for n = 2k the algebras su* (4k) which are parabolically related to the CLA su(n,n). Further we consider the algebras sp(r,r) which are parabolically related to the CLA sp(2r, Bbb R). We consider also E6(6) and E6(2) which are parabolically related to the hermitian symmetric case E6(-14),
TUG-OF-WAR GAMES AND PARABOLIC PROBLEMS WITH SPATIAL AND TIME DEPENDENCE
Rossi, Julio D.
TUG-OF-WAR GAMES AND PARABOLIC PROBLEMS WITH SPATIAL AND TIME DEPENDENCE LEANDRO M. DEL PEZZO AND JULIO D. ROSSI Abstract. In this paper we use probabilistic arguments (Tug-of-War games) to obtain in this article is to look for parabolic PDEs that may arise as continuous values of Tug-of-War games when one
ERROR ESTIMATES FOR THE FINITE VOLUME ELEMENT METHOD FOR PARABOLIC EQUATIONS IN CONVEX POLYGONAL
Lazarov, Raytcho
ERROR ESTIMATES FOR THE FINITE VOLUME ELEMENT METHOD FOR PARABOLIC EQUATIONS IN CONVEX POLYGONAL piecewise linear finite volume element method for parabolic equations in a convex polygonal domain as in the corresponding finite element method, and almost optimal away from the corners. We also briefly consider
Parabolic equation solution of seismo-acoustics problems involving variations in bathymetry to extend this approach to a larger class of seismo-acoustics problems. The variable rotated parabolic on improving accuracy for range-dependent seismo-acoustics problems. The introduction of the ur,w formulation,6
Blow-up at the Boundary for Degenerate Semilinear Parabolic Equations
Floater, Michael S.
Blow-up at the Boundary for Degenerate Semilinear Parabolic Equations M. S. Floater Department a superlinear parabolic equation, degenerate in the time derivative. It is shown that the solution may blow up in finite time. Moreover it is proved that for a large class of initial data blow-up occurs at the boundary
Solar power water distillation unit
NASA Astrophysics Data System (ADS)
Hameed, Kamran; Muzammil Khan, Muhammad; Shahrukh Ateeq, Ijlal; Omair, Syed Muhammad; Ahmer, Muhammad; Wajid, Abdul
2013-06-01
Clean drinking water is the basic necessity for every human being, but about 1.1 billion people in the world lacked proper drinking water. There are many different types of water purification processes such as filtration, reverse osmosis, ultraviolet radiation, carbon absorption, but the most reliable processes are distillation and boiling. Water purification, such as distillation, is especially important in regions where water resources or tap water is not suitable for ingesting without boiling or chemical treatment. In design project It treats the water by combining different methods such as Filtration, Distillation and a technique called concentrated solar power (CSP). Distillation is literally the method seen in nature, whereby: the sun heats the water on the earth's surface, the water is turned into a vapor (evaporation) and rises, leaving contaminants behind, to form clouds. As the upper atmosphere drops in temperature the vapors cool and convert back to water to form water. In this project distillation is achieved by using a parabolic mirror which boils water at high temperature. Filtration is done by sand filter and carbon filter. First sand filter catches the sand particles and the carbon filter which has granules of active carbon is used to remove odor dissolved gases from water. This is the Pre-treatment of water. The filtered water is then collected in a water container at a focus of parabolic mirror where distillation process is done. Another important feature of designed project is the solar tracking of a parabolic mirror which increases the efficiency of a parabolic mirror [1],[2].
Control system for Parabolic Dish Concentrator No. 1
Stallkamp, J.A.
1985-03-15
This report is a description and discussion of the control system for Parabolic Dish Concentrator No. 1 (PDC-1) as used at the JPL Parabolic Dish Test Site (PDTS). The tracking action is a discontinuous, start/stop motion with sun sensors for primary control and a computed sun ephemeris for a simultaneous check and cloud passage. Project background, functional requirements, and hardware description are presented in brief form. System operation is described in considerable detail and includes the precise message exchange protocol between the module and remote control station, the initialization process, the command list, and the basic control logic used in the local microprocessor. System installation and performance items are given; the unit operated very satisfactorily for the brief period of time before it was moved to Sandia National Laboratories at Albuquerque, New Mexico. It was operated at a 0.05-deg deadband for optical characterization of the reflecting surfaces and mirror geometry. The last section includes significant presentations and discussions of (1) protection against burn by the sun in the case of failure to continue to track and (2) other equipment and personnel safety items. Operation of PDC-1 at the test site was man-attended; for extension to man-unattended operation a number of additional requirements and constraints must be identified and a full implementation of the capabilities of the design performed.
Quantum Confined Stark Effect in Wide Parabolic Quantum Wells
Sylwia Zieli?ska-Raczy?ska; Gerard Czajkowski; David Ziemkiewicz
2015-07-30
We show how to compute the optical functions of Wide Parabolic Quantum Wells (WPQWs) exposed to uniform electric F applied in the growth direction, in the excitonic energy region. The effect of the coherence between the electron-hole pair and the electromagnetic field of the propagating wave including the electron-hole screened Coulomb potential is adopted, and the valence band structure is taken into account in the cylindrical approximation. The role of the interaction potential and of the applied electric field, which mix the energy states according to different quantum numbers and create symmetry forbidden transitions, is stressed. We use the Real Density Matrix Approach (RDMA) and an effective e-h potential, which enable to derive analytical expressions for the WPQWs electrooptical functions. Choosing the susceptibility, we performed numerical calculations appropriate to a GaAs/GaAlAs WPQWs. We have obtained a red shift of the absorption maxima (Quantum Confined Stark Effect), asymmetric upon the change of the direction of the applied field (F -> -F), parabolic for the ground state and strongly dependent on the confinement parameters (the QWs sizes), changes in the oscillator strengths, and new peaks related to the states with different parity for electron and hole.
Altered osteoblast structure and function in parabolic flight
NASA Astrophysics Data System (ADS)
Zhong-Quan, Dai; Ying-Hui, Li; Fen, Yang; Bai, Ding; Ying-Jun, Tan
Introduction Bone loss has a significant impact on astronauts during spaceflight being one of the main obstacles preventing interplanetary missions However the exact mechanism is not well understood In the present study we investigated the effects of acute gravitational changes generated by parabolic flight on the structure and function of osteoblasts ROS17 2 8 carried by airbus A300 Methods The alteration of microfilament cytoskeleton was observed by the Texas red conjugated Phalloidin and Alexa Fluor 488 conjugated DNase I immunofluorescence stain ALP activity and expression COL1A1 expression osteocalcin secrete which presenting the osteoblast function were detected by modified calcium and cobalt method RT-PCR and radioimmunity methods respectively Results The changed gravity induced the reorganization of microfilament cytoskeleton of osteoblast After 3 hours parabolic flight F-actin of osteoblast cytoskeleton became more thickness and directivity whereas G-actin reduced and relatively concentrated at the edge of nucleus observed by confocal fluorescence microscopy This phenomenon is identical with structure alternation observed in hypergravity but the osteoblast function decrease The excretion of osteocalcin the activity and mRNA expression of ALP decrease but the COL1A1 expression has no changes These results were similar to the changes in simulated or real microgravity Conclusion Above results suggest that short time gravity alternative change induce osteoblast structure and function
Theory of Parabolic Arcs in Interstellar Scintillation Spectra
NASA Astrophysics Data System (ADS)
Cordes, James M.; Rickett, Barney J.; Stinebring, Daniel R.; Coles, William A.
2006-01-01
Interstellar scintillation (ISS), observed as time variation in the intensity of a compact radio source, is caused by small-scale structure in the electron density of the interstellar plasma. Dynamic spectra of ISS show modulation in radio frequency and time. Here we relate the (two-dimensional) power spectrum of the dynamic spectrum-the secondary spectrum-to the scattered image of the source. Recent work has identified remarkable parabolic arcs in secondary spectra. Each point in a secondary spectrum corresponds to interference between points in the scattered image with a certain Doppler shift and a certain delay. The parabolic arc corresponds to the quadratic relation between differential Doppler shift and delay through their common dependence on scattering angle. We show that arcs will occur in all media that scatter significant power at angles larger than the rms angle. Thus, effects such as source diameter, steep spectra, and dissipation scales, which truncate high angle scattering, also truncate arcs. Arcs are equally visible in simulations of nondispersive scattering. They are enhanced by anisotropic scattering when the spatial structure is elongated perpendicular to the velocity. In weak scattering the secondary spectrum is directly mapped from the scattered image, and this mapping can be inverted. We discuss additional observed phenomena including multiple arcs and reverse arclets oriented oppositely to the main arc. These phenomena persist for many refractive scattering times, suggesting that they are due to large-scale density structures, rather than low-frequency components of Kolmogorov turbulence.
Second law analysis and optimization of a parabolic trough receiver tube for direct steam generation
NASA Astrophysics Data System (ADS)
Nolte, H. C.; Bello-Ochende, T.; Meyer, J. P.
2015-06-01
Entropy generation in the receiver tube of a parabolic trough solar collector can mainly be attributed to the fluid friction and finite temperature differences. The contribution of each of these components is investigated under different circumstances. Mass flow rates, tube diameters and operating pressures are investigated to obtain good guidelines for receiver tube and plant design. Operating pressures between 3 MPa (saturation temperature of 233.9 °C) and 9 MPa (saturation temperature of 303.3 °C) were investigated. Results show that small diameters can result in excessive fluid friction, especially when the mass flow rates are high. For most cases, tube diameters beyond 20 mm will exclusively be subject to entropy generation due to finite temperature differences, and entropy generation due to fluid friction will be small to negligible. Increasing the concentration ratio will decrease entropy generation, due to a higher heat flux per unit meter. This will ultimately result in shorter receiver tube lengths. From a simulated annealing optimization it was seen that if the diameter is increased, the entropy generation can be lowered, provided that the concentration ratio is kept constant. However, beyond a certain point gains in minimizing the entropy generation become negligible. The optimal operating pressure will generally increase if the mass flow rate is increased. Finally it was seen that higher operating pressures are more advantageous when the entropy generation minimization is considered in conjunction with the work output.
Harrison, T.D.
1981-03-01
Sandia National Laboratories, Albuquerque (SNLA), is currently conducting a program to predict the performance and measure the characteristics of commercially available solar collectors that have the potential for use in industrial process heat and enhanced oil recovery applications. The thermal performance predictions for the Sun-Heet nontracking, line-focusing parabolic trough collector at five cities in the US are presented. (WHK)
Air Brayton Solar Receiver, phase 2
NASA Technical Reports Server (NTRS)
Deanda, L. E.
1981-01-01
An air Brayton solar receiver (ABSR) is discussed. The ABSR consists of a cylindrical, insulated, offset plate fin heat exchanger which is mounted at the focal plane of a fully tracking parabolic solar collector. The receiver transfer heat from the concentrated solar radiation (which impinges on the inside walls of the heat exchanger) to the working fluid i.e., air. The hot air would then e used to drive a small Brayton cycle heat engine. The engine in turn drives a generator which produces electrical energy. Symmetrical and asymmetrical solar power input into the ABSR are analyzed. The symmetrical cases involve the baseline incident flux and the axially shifted incident fluxes. The asymmetrical cases correspond to the solar fluxes that are obtained by reduced solar input from one half of the concentrator or by receiver offset of plus or minus 1 inch from the concentrator optical axis.
Parabolic flight induces changes in gene expression patterns in Arabidopsis thaliana.
Paul, Anna-Lisa; Manak, Michael S; Mayfield, John D; Reyes, Matthew F; Gurley, William B; Ferl, Robert J
2011-10-01
Our primary objective was to evaluate gene expression changes in Arabidopsis thaliana in response to parabolic flight as part of a comprehensive approach to the molecular biology of spaceflight-related adaptations. In addition, we wished to establish parabolic flight as a tractable operations platform for molecular biology studies. In a succession of experiments on NASA's KC-135 and C-9 parabolic aircraft, Arabidopsis plants were presented with replicated exposure to parabolic flight. Transcriptome profiling revealed that parabolic flight caused changes in gene expression patterns that stood the statistical tests of replication on three different flight days. The earliest response, after 20 parabolas, was characterized by a prominence of genes associated with signal transduction. After 40 parabolas, this prominence was largely replaced by genes associated with biotic and abiotic stimuli and stress. Among these responses, three metabolic processes stand out in particular: the induction of auxin metabolism and signaling, the differential expression of genes associated with calcium-mediated signaling, and the repression of genes associated with disease resistance and cell wall biochemistry. Many, but not all, of these responses are known to be involved in gravity sensing in plants. Changes in auxin-related gene expression were also recorded by reporter genes tuned to auxin signal pathways. These data demonstrate that the parabolic flight environment is appropriate for molecular biology research involving the transition to microgravity, in that with replication, proper controls, and analyses, gene expression changes can be observed in the time frames of typical parabolic flight experiments. PMID:21970703
Barchan-parabolic dune pattern transition from vegetation stability threshold
NASA Astrophysics Data System (ADS)
Reitz, Meredith D.; Jerolmack, Douglas J.; Ewing, Ryan C.; Martin, Raleigh L.
2010-10-01
Many dune fields exhibit a downwind transition from forward-pointing barchan dunes to stabilized, backward-pointing parabolic dunes, accompanied by an increase in vegetation. A recent model predicts this pattern transition occurs when dune surface erosion/deposition rates decrease below a threshold of half the vegetation growth rate. We provide a direct test using a unique data set of repeat topographic surveys across White Sands Dune Field and find strong quantitative support for the model threshold. We also show the threshold hypothesis applied to a barchan dune results naturally in its curvature inversion, as the point of threshold crossing progresses from the horns to the crest. This simple, general threshold framework can be an extremely useful tool for predicting the response of dune landscapes to changes in wind speed, sediment supply, or vegetation growth rate. Near the threshold, a small environmental change could result in a drastic change in dune pattern and activity.
Parabolic dish Stirling module development and test results
Washom, B.
1984-08-01
Private industry and the U.S. Department of Energy are presently cost sharing the design, manufacture and test of a 25 Kwe parabolic dish Stirling module, known as Vanguard. The Vanguard module achieved a world's record sunlight to electric conversion efficiency of 31.6% in February 1984 at the Rancho Mirage, California test site. The module is presently operating daily in sunrise to sunset tests to determine the long term performance and O and M requirements of this distributed receiver system. Each module can be easily integrated into a larger field of modules to provide power generation opportunities from a single 25 Kwe unit for isolated loads to 30 Mwe systems for integrated utility power generation.
An upwind algorithm for the parabolized Navier-Stokes equations
NASA Astrophysics Data System (ADS)
Lawrence, S. L.; Tannehill, J. C.; Chaussee, D. S.
1986-05-01
A new upwind algorithm based on Roe's scheme has been developed to solve the two-dimensional parabolized Navier-Stokes (PNS) equations. This method does not require the addition of user specified smoothing terms for the capture of discontinuities such as shock waves. Thus, the method is easy to use and can be applied without modification to a wide variety of supersonic flowfields. The advantages and disadvantages of this adaptation are discussed in relation to those of the conventional Beam-Warming scheme in terms of accuracy, stability, computer time and storage, and programming effort. The new algorithm has been validated by applying it to three laminar test cases including flat plate boundary-layer flow, hypersonic flow past a 15 deg compression corner, and hypersonic flow into a converging inlet. The computed results compare well with experiment and show a dramatic improvement in the resolution of flowfield details when compared with the results obtained using the conventional Beam-Warming algorithm.
An upwind algorithm for the parabolized Navier-Stokes equations
NASA Technical Reports Server (NTRS)
Lawrence, S. L.; Tannehill, J. C.; Chaussee, D. S.
1986-01-01
A new upwind algorithm based on Roe's scheme has been developed to solve the two-dimensional parabolized Navier-Stokes (PNS) equations. This method does not require the addition of user specified smoothing terms for the capture of discontinuities such as shock waves. Thus, the method is easy to use and can be applied without modification to a wide variety of supersonic flowfields. The advantages and disadvantages of this adaptation are discussed in relation to those of the conventional Beam-Warming scheme in terms of accuracy, stability, computer time and storage, and programming effort. The new algorithm has been validated by applying it to three laminar test cases including flat plate boundary-layer flow, hypersonic flow past a 15 deg compression corner, and hypersonic flow into a converging inlet. The computed results compare well with experiment and show a dramatic improvement in the resolution of flowfield details when compared with the results obtained using the conventional Beam-Warming algorithm.
Cardiovascular changes in parabolic flights assessed by ballistocardiography.
Deličre, Q; Migeotte, P-F; Neyt, X; Funtova, I; Baevsky, R M; Tank, J; Pattyn, N
2013-01-01
This paper presents a comparison of the cardiovascular changes observed in microgravity as compared to ground based measurements. The ballistocardiogram (BCG), the electrocardiogram (ECG) and the transthoracic impedance cardiogram (ICG) were recorded on five healthy subjects during the 57th-European Space Agency (ESA) parabolic flight campaign. BCG is analyzed though its most characteristic wave, the IJ wave complex that can be identified along the longitudinal component of BCG and which has been demonstrated to be linked to cardiac ejection. The timings between the contraction of the heart and the ejection of blood in the aorta are analyzed via the time delay between the R-wave of the ECG and the I and J-waves of BCG (RI and RJ intervals respectively). Our results show that the IJ complex presents a larger amplitude in weightlessness and suggest that stroke volume (SV) increases in microgravity. We assume that ballistocardiography is an efficient method to assess the ventricular performance. PMID:24110559
Self adaptive methods for parabolic partial differential equations
Gannon, D.B.
1980-08-01
In many applications, the solutions to important partial differential equations are characterized by a sharp active region of transition (such as wave fronts or areas of rapid diffusion) surrounded by relatively calm stable regions. The numerical approximation to such a solution is based on a mesh or grid structure that is best when very fine in the active region and coarse in the calm region. This work considers algorithms for the proper construction of locally refined grids for finite element-based methods for the solution to such problems. Refinement criteria are developed and tested for parabolic problems. The computational complexity of such a strategy is studied, and algorithms based on nested dissection are presented to solve the associated linear algebra problems. 17 figures, 4 tables.
Optimal Control of a Parabolic Equation with Dynamic Boundary Condition
Hoemberg, D. Krumbiegel, K.; Rehberg, J.
2013-02-15
We investigate a control problem for the heat equation. The goal is to find an optimal heat transfer coefficient in the dynamic boundary condition such that a desired temperature distribution at the boundary is adhered. To this end we consider a function space setting in which the heat flux across the boundary is forced to be an L{sup p} function with respect to the surface measure, which in turn implies higher regularity for the time derivative of temperature. We show that the corresponding elliptic operator generates a strongly continuous semigroup of contractions and apply the concept of maximal parabolic regularity. This allows to show the existence of an optimal control and the derivation of necessary and sufficient optimality conditions.
Context-specific adaptation of saccade gain in parabolic flight
NASA Technical Reports Server (NTRS)
Shelhamer, Mark; Clendaniel, Richard A.; Roberts, Dale C.
2002-01-01
Previous studies established that vestibular reflexes can have two adapted states (e.g., gains) simultaneously, and that a context cue (e.g., vertical eye position) can switch between the two states. Our earlier work demonstrated this phenomenon of context-specific adaptation for saccadic eye movements: we asked for gain decrease in one context state and gain increase in another context state, and then determined if a change in the context state would invoke switching between the adapted states. Horizontal and vertical eye position and head orientation could serve, to varying degrees, as cues for switching between two different saccade gains. In the present study, we asked whether gravity magnitude could serve as a context cue: saccade adaptation was performed during parabolic flight, which provides alternating levels of gravitoinertial force (0 g and 1.8 g). Results were less robust than those from ground experiments, but established that different saccade magnitudes could be associated with different gravity levels.
Cerebral vasoconstriction precedes orthostatic intolerance after parabolic flight
NASA Technical Reports Server (NTRS)
Serrador, J. M.; Shoemaker, J. K.; Brown, T. E.; Kassam, M. S.; Bondar, R. L.; Schlegel, T. T.
2000-01-01
The effects of brief but repeated bouts of micro- and hypergravity on cerebrovascular responses to head-up tilt (HUT) were examined in 13 individuals after (compared to before) parabolic flight. Middle cerebral artery mean flow velocity (MCA MFV; transcranial Doppler ultrasound), eye level blood pressure (BP) and end tidal CO(2) (P(ET)CO(2)) were measured while supine and during 80 degrees HUT for 30 min or until presyncope. In the postflight tests subjects were classified as being orthostatically tolerant (OT) (n = 7) or intolerant (OI) (n = 6). BP was diminished with HUT in the OT group in both tests (p < 0.05) whereas postflight BP was not different from supine in the OI group. Postflight compared to preflight, the reduction in P(ET)CO(2) with HUT (p < 0.05) increased in both groups, although significantly so only in the OI group (p < 0.05). The OI group also had a significant decrease in supine MCA MFV postflight (p < 0.05) that was unaccompanied by a change in supine P(ET)CO(2). The decrease in MCA MFV that occurred during HUT in both groups preflight (p < 0.05) was accentuated only in the OI group postflight, particularly during the final 30 s of HUT (p < 0.05). However, this accentuated decrease in MCA MFV was not correlated to the greater decrease in P(ET)CO(2) during the same period (R = 0.20, p = 0.42). Although cerebral vascular resistance (CVR) also increased in the OI group during the last 30 s of HUT postflight (p < 0.05), the dynamic autoregulatory gain was not simultaneously changed. Therefore, we conclude that in the OI individuals, parabolic flight was associated with cerebral hypoperfusion following a paradoxical augmentation of CVR by a mechanism that was not related to changes in autoregulation nor strictly to changes in P(ET)CO(2).
Nonlocal operators, parabolic-type equations, and ultrametric random walks
Chacón-Cortes, L. F. Zúńiga-Galindo, W. A.
2013-11-15
In this article, we introduce a new type of nonlocal operators and study the Cauchy problem for certain parabolic-type pseudodifferential equations naturally associated to these operators. Some of these equations are the p-adic master equations of certain models of complex systems introduced by Avetisov, V. A. and Bikulov, A. Kh., “On the ultrametricity of the fluctuation dynamicmobility of protein molecules,” Proc. Steklov Inst. Math. 265(1), 75–81 (2009) [Tr. Mat. Inst. Steklova 265, 82–89 (2009) (Izbrannye Voprosy Matematicheskoy Fiziki i p-adicheskogo Analiza) (in Russian)]; Avetisov, V. A., Bikulov, A. Kh., and Zubarev, A. P., “First passage time distribution and the number of returns for ultrametric random walks,” J. Phys. A 42(8), 085003 (2009); Avetisov, V. A., Bikulov, A. Kh., and Osipov, V. A., “p-adic models of ultrametric diffusion in the conformational dynamics of macromolecules,” Proc. Steklov Inst. Math. 245(2), 48–57 (2004) [Tr. Mat. Inst. Steklova 245, 55–64 (2004) (Izbrannye Voprosy Matematicheskoy Fiziki i p-adicheskogo Analiza) (in Russian)]; Avetisov, V. A., Bikulov, A. Kh., and Osipov, V. A., “p-adic description of characteristic relaxation in complex systems,” J. Phys. A 36(15), 4239–4246 (2003); Avetisov, V. A., Bikulov, A. H., Kozyrev, S. V., and Osipov, V. A., “p-adic models of ultrametric diffusion constrained by hierarchical energy landscapes,” J. Phys. A 35(2), 177–189 (2002); Avetisov, V. A., Bikulov, A. Kh., and Kozyrev, S. V., “Description of logarithmic relaxation by a model of a hierarchical random walk,” Dokl. Akad. Nauk 368(2), 164–167 (1999) (in Russian). The fundamental solutions of these parabolic-type equations are transition functions of random walks on the n-dimensional vector space over the field of p-adic numbers. We study some properties of these random walks, including the first passage time.
Acute hemodynamic responses to weightlessness during parabolic flight.
Mukai, C N; Lathers, C M; Charles, J B; Bennett, B S; Igarashi, M; Patel, S
1991-10-01
Pilots and astronauts experience fluid shifts in variable gravity. Acute effects of fluid shifts on the cardiovascular system were monitored on NASA's KC-135 aircraft during parabolic flight. The variability of R-R intervals in the electrocardiogram was measured as an indication of vagal cardiac neural activity. R-R intervals were measured during the gravity transition from 2-G to 0-G produced by parabolic flight to assess the involvement of the autonomic nervous system in regulating the acute effects of fluid shifts. In seven subjects, a BoMed noninvasive continuous cardiac output monitor (NCCOM 3) monitored thoracic fluid index (TFI, ohms), heart rate (bpm), and cardiac output (1/min). Data were stored on a lap-top computer with the subject in one of four postures: sitting, standing, supine, and semi-supine, during one of four sets of eight to ten parabolas. Five seconds of data were averaged: before parabola onset (1.3-G); parabola entry (1.9-G); 0-G; and parabola exit (1.7-G). Three to eight parabolas were averaged for subjects in each posture; the mean for each posture was calculated. In each of five additional subjects, the coefficient of variation was calculated by dividing mean value by the standard deviation of 3 to 15 R-R intervals. Eight to ten parabolas were averaged for each postural set. Compared with values collected before 0-G, standing values during 0-G showed that the thoracic fluid index decreased 2.5 ohms, heart rate decreased 22 bpm, and cardiac output increased 1 L/min. During sitting, thoracic fluid index decreased 1.25 ohms, heart rate decreased 10 bpm, whereas cardiac output increased 0.5 L/min.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:1761733
Critical Solutions of Three Vortex Motion in the Parabolic Case
Lu Ting; Omar Knio; Denis Blackmore
2008-07-02
Grobli (1877) laid the foundation for the analysis of the motion of three point vortices in a plane by deriving governing equations for triangular configurations of the vortices. Synge (1949) took this formulation one step further to that of a similar triangle of unit perimeter, via trilinear coordinates. The final reduced problem is governed by an integrable two-dimensional system of differential equations with solutions represented as planar trajectories. Another key to Synge's analysis was his classification of the problem into three distinct cases: elliptic, hyperbolic and parabolic corresponding, respectively, to the sum of products of pairs of vortex strengths being positive, negative or zero. The reduction of the vortex configuration, a curve in space to a planar curve is one-to-one, except along a critical planar curve C in the parabolic case. Each point on C represents a triangle of unit perimeter corresponding to a family of similar vortex configurations, expanding or contracting. The latter would lead to coelescence of the three vortices. Tavantzis and Ting (1988) filled most of the gaps left by Synge regarding the dynamics of the problem, and showed in particular that points on C corresponding to similar expanding families of vortex configurations are stable while those corresponding to similar contracting families are unstable. Their investigations yielded an exhaustive description of the motion and stability of three vortices in a plane except for the global behavior of the vortex configurations in a narrow strip containing C. The main contribution of this paper is a complete description of the global dynamics in such a strip, which emphaticallly demonstrates that three distinct vortices almost never coalesce.
Parabolic growth patterns in 96-well plate cell growth experiments.
Faessel, H M; Levasseur, L M; Slocum, H K; Greco, W R
1999-05-01
In preparing for the routine use of the ubiquitous in vitro cell growth inhibition assay for the study of anticancer agents, we characterized the statistical properties of the assay and found some surprising results. Parabolic well-to-well cell growth patterns were discovered, which could profoundly affect the results of routine growth inhibition studies of anticancer and other agents. Four human ovarian cell lines, A2780/WT, A2780/DX5, A2780/DX5B, and A121, and one human ileocecal adenocarcinoma cell line, HCT-8, were seeded into plastic 96-well plates with a 12-channel pipette, without drugs, and grown from 1-5 d. The wells were washed with a plate washer, cells stained with sulforhodamine B (SRB), and dye absorbance measured with a plate reader. Variance models were fit to the data from replicates to determine the nature of the heteroscedastic error structure. Exponential growth models were fit to data to estimate doubling times for each cell line. Polynomial models were fit to data from 10-plate stacks of 96-well plates to explore nonuniformity of cell growth in wells in different regions of the stacks. Each separate step in the assay was examined for precision, patterns, and underlying causes of variation. Differential evaporation of water from wells is likely a major, but not exclusive, contributor to the systematic well-to-well cell growth patterns. Because the fundamental underlying causes of the parabolic growth patterns were not conclusively found, a randomization step for the growth assay was developed. PMID:10475273
NASA Astrophysics Data System (ADS)
Dobrev, V. K.
2013-02-01
In the present paper we continue the project of systematic construction of invariant differential operators for non-compact semisimple Lie groups. Our starting points is the class of algebras, which we call 'conformal Lie algebras' (CLA), which have very similar properties to the conformal algebras of Minkowski space-time, though our aim is to go beyond this class in a natural way. For this we introduce the new notion of parabolic relation between two non-compact semisimple Lie algebras G and G ' that have the same complexification and possess maximal parabolic subalgebras with the same complexification. Thus, we consider the exceptional algebra E 7(7) which is parabolically related to the CLA E 7(-25) , the parabolic subalgebras including E 6(6) and E 6(-26). Other interesting examples are the orthogonal algebras so(p, q) all of which are parabolically related to the conformal algebra so( n, 2) with p + q = n + 2, the parabolic subalgebras including the Lorentz subalgebra so( n - 1, 1) and its analogs so( p - 1, q - 1). We consider also E6(6) and E6(2) which are parabolically related to the hermitian symmetric case E6(-14) , the parabolic subalgebras including real forms of sl(6). We also give a formula for the number of representations in the main multiplets valid for CLAs and all algebras that are parabolically related to them. In all considered cases we give the main multiplets of indecomposable elementary representations including the necessary data for all relevant invariant differential operators. In the case of so( p, q) we give also the reduced multiplets. We should stress that the multiplets are given in the most economic way in pairs of shadow fields. Furthermore we should stress that the classification of all invariant differential operators includes as special cases all possible conservation laws and conserved currents, unitary or not.
V. K. Dobrev
2015-10-22
In the present paper we continue the project of systematic construction of invariant differential operators for non-compact semisimple Lie groups. Our starting points is the class of algebras, which we call 'conformal Lie algebras' (CLA), which have very similar properties to the conformal algebras of Minkowski space-time, though our aim is to go beyond this class in a natural way. For this we introduce the new notion of {\\it parabolic relation} between two non-compact semisimple Lie algebras g and g' that have the same complexification and possess maximal parabolic subalgebras with the same complexification. Thus, we consider the exceptional algebra E_{7(7)} which is parabolically related to the CLA E_{7(-25)}, the parabolic subalgebras including E_{6(6)} and E_{6(-6)} . Other interesting examples are the orthogonal algebras so(p,q) all of which are parabolically related to the conformal algebra so(n,2) with p+q=n+2, the parabolic subalgebras including the Lorentz subalgebra so(n-1,1) and its analogs so(p-1,q-1). We consider also E_{6(6)} and E_{6(2)} which are parabolically related to the hermitian symmetric case E_{6(-14)}, the parabolic subalgebras including real forms of sl(6). We also give a formula for the number of representations in the main multiplets valid for CLAs and all algebras that are parabolically related to them. In all considered cases we give the main multiplets of indecomposable elementary representations including the necessary data for all relevant invariant differential operators. In the case of so(p,q) we give also the reduced multiplets. We should stress that the multiplets are given in the most economic way in pairs of {\\it shadow fields}. Furthermore we should stress that the classification of all invariant differential operators includes as special cases all possible {\\it conservation laws} and {\\it conserved currents}, unitary or not.
Federal Register 2010, 2011, 2012, 2013, 2014
2010-04-19
... use parabolic trough solar thermal technology to produce electrical power using steam turbine generators fed from solar steam generators. The generators would connect to a new SSEP 500-kilovolt onsite... County, Arizona, was published in the Federal Register on July 8, 2009 (74 FR 32641). The BLM held...
NASA Astrophysics Data System (ADS)
Xiang, Tian
2015-06-01
In this paper, we are concerned with a general class of quasilinear parabolic-parabolic chemotaxis systems with/without growth source, under homogeneous Neumann boundary conditions in a smooth bounded domain ? ?Rn with n ? 2. It is recently known that blowup is possible even in the presence of superlinear growth restrictions. Here, we derive new and interesting characterizations on the growth versus the boundedness. We show that the hard task of proving the L?-boundedness of the cell density can be reduced to proving its Lr-boundedness. In other words, we show that the Lr-boundedness of the cell density can successfully guarantee its L?-boundedness and hence its global boundedness, where r = n + ? or n/2 + ? depending on whether the growth restriction is essentially linear (including no growth) or superlinear. Hence, a blowup solution also blows up in Lp-norm for any suitably large p. More detailed information on how the growth source affects the boundedness of the solution is derived. These results reveal deep understandings of blowup mechanism for chemotaxis models. Then we use these criteria to establish uniform boundedness and hence global existence of the underlying models: logistic source in 2-D, cubic source as initially proposed by Mimura and Tsujikawa in 3-D, [ (n - 1) + ? ]st source in n-D with n ? 4. As a consequence, in a chemotaxis-growth model, blowup is impossible if the growth effect is suitably strong. Finally, we underline that our results remove the commonly assumed convexity on the domain ?.
The Pressure-Cooker Presidency
ERIC Educational Resources Information Center
McLaughlin, Judith Block
2006-01-01
When the AGB task force on the state of the Presidency in American Higher Education was meeting last fall in Washington, D.C., to deliberate about the role of the academic presidency, the Secretary of Education's Commission on the Future of Higher Education convened across town to examine issues ranging from access to affordability to…
Solar thermal electricity generation
NASA Astrophysics Data System (ADS)
Gasemagha, Khairy Ramadan
1993-01-01
This report presents the results of modeling the thermal performance and economic feasibility of large (utility scale) and small solar thermal power plants for electricity generation. A number of solar concepts for power systems applications have been investigated. Each concept has been analyzed over a range of plant power ratings from 1 MW(sub e) to 300 MW(sub e) and over a range of capacity factors from a no-storage case (capacity factor of about 0.25 to 0.30) up to intermediate load capacity factors in the range of 0.46 to 0.60. The solar plant's economic viability is investigated by examining the effect of various parameters on the plant costs (both capital and O & M) and the levelized energy costs (LEC). The cost components are reported in six categories: collectors, energy transport, energy storage, energy conversion, balance of plant, and indirect/contingency costs. Concentrator and receiver costs are included in the collector category. Thermal and electric energy transport costs are included in the energy transport category. Costs for the thermal or electric storage are included in the energy storage category; energy conversion costs are included in the energy conversion category. The balance of plant cost category comprises the structures, land, service facilities, power conditioning, instrumentation and controls, and spare part costs. The indirect/contingency category consists of the indirect construction and the contingency costs. The concepts included in the study are (1) molten salt cavity central receiver with salt storage (PFCR/R-C-Salt); (2) molten salt external central receiver with salt storage (PFCR/R-E-Salt); (3) sodium external central receiver with sodium storage (PFCR/RE-Na); (4) sodium external central receiver with salt storage (PFCR/R-E-Na/Salt); (5) water/steam external central receiver with oil/rock storage (PFCR/R-E-W/S); (6) parabolic dish with stirling engine conversion and lead acid battery storage (PFDR/SLAB); (7) parabolic dish with stirling engine conversion and redox advanced battery storage (PFDR/S-RAB); and (8) parabolic trough with oil/rock storage (LFDR/R-HT-45). Key annual efficiency and economic results of the study are highlighted in tabular format for plant sizes and capacity factor that resulted in the lowest LEC over the analysis range.
The Coolidge Solar Irrigation Project
NASA Astrophysics Data System (ADS)
Torkelson, L.; Larson, D. L.
1981-02-01
The solar irrigation facility consists of a 2136.8 m(2) (23,000 ft(2)) line-focus parabolic trough collector subsystem, a 113.55 m(3) (30,000 gallon) thermal storage subsystem, and a 150 kW/sub e/ (142.2 Btu/s) organic Rankine cycle power generation unit. The performance of the facility and its operational and maintenance requirements are reported. The period from the facility's initial operation in October 1979 to 31 August 1980 is covered.
Not Available
2010-12-01
Parabolic trough technology is the most mature of the various concentrating solar power (CSP) options. But scientists at the National Renewable Energy Laboratory (NREL) continue to make advances on trough systems through innovative research on various components in industrial partnerships with Acciona Solar Power, SkyFuel, Schott Solar, and others. The results are leading to improved system efficiencies and lower costs for CSP plants.
Fuhrman, Marco Tessitore, Gianmario
2005-05-15
We study a forward-backward system of stochastic differential equations in an infinite-dimensional framework and its relationships with a semilinear parabolic differential equation on a Hilbert space, in the spirit of the approach of Pardoux-Peng. We prove that the stochastic system allows us to construct a unique solution of the parabolic equation in a suitable class of locally Lipschitz real functions. The parabolic equation is understood in a mild sense which requires the notion of a generalized directional gradient, that we introduce by a probabilistic approach and prove to exist for locally Lipschitz functions.The use of the generalized directional gradient allows us to cover various applications to option pricing problems and to optimal stochastic control problems (including control of delay equations and reaction-diffusion equations),where the lack of differentiability of the coefficients precludes differentiability of solutions to the associated parabolic equations of Black-Scholes or Hamilton-Jacobi-Bellman type.
On parabolic stochastic integro-differential equations: existence, regularity and numerics
Leahy, James-Michael
2015-07-01
In this thesis, we study the existence, uniqueness, and regularity of systems of degenerate linear stochastic integro-differential equations (SIDEs) of parabolic type with adapted coefficients in the whole space. We also ...
Hall, Eric Joseph
2013-07-01
First we consider implicit finite difference schemes on uniform grids in time and space for second order linear stochastic partial differential equations of parabolic type. Under sufficient regularity conditions, we prove ...
NASA Technical Reports Server (NTRS)
Kohl, Randall L.
1987-01-01
The concentrations of adrenocorticotropic hormone (ACTH), vasopressin (AVP), epinephrine (EPI), and norepinephrine (NE) in 22 subjects administered 10 to 20 mg of metoclopramide prior to parabolic flight are measured. The effect of metoclopramide on motion sickness is examined. It is observed that metoclopramide is ineffective in the modulation of motion sickness due to stressful linear and angular acceleration and orbital flight, and it does not affect serum hormones prior to parabolic flight. It is detected that the serum level of AVP declines following emesis induced by parabolic flight and stressful angular acceleration; the serum levels of ACTH and EPI are elevated by parabolic flight and stressful angular acceleration; and serum NE is significantly elevated immediately following emesis. The possible roles of these hormones in the etiology of space motion sickness are discussed.
Matioc, Bogdan-Vasile
2011-01-01
We prove global existence of nonnegative weak solutions for a strongly coupled, fourth order degenerate parabolic system governing the motion of two thin fluid layers in a porous medium when capillarity is the sole driving mechanism.
Yang, Daoqi
Improved Error Estimation of Dynamic Finite Element Methods for Second Order Parabolic Equations problems. Standard, characteristic, and mixed finite element methods with dynamic function spaces the finite element method requires capabilities for efficient, dynamic, and selfadaptive local grid
Approximation of Parabolic Problems on Grids Locally Refined in Time and Space \\Lambda
Ewing, Richard E.
Approximation of Parabolic Problems on Grids Locally Refined in Time and Space \\Lambda R.E. Ewing y], Erikson and Johnson [9, 10], Heroux and Thomas [19], Ewing, Lazarov, and Vassilevski [16, 17], and Ewing
A Class of Nonlocal Coupled Semilinear Parabolic System with Nonlocal Boundaries
Liu, Hong; Lu, Haihua
2014-01-01
We investigate the positive solutions of the semilinear parabolic system with coupled nonlinear nonlocal sources subject to weighted nonlocal Dirichlet boundary conditions. The blow-up and global existence criteria are obtained. PMID:24696665
Biosignal alterations generated by parabolic flights of small aerobatic aircrafts
NASA Astrophysics Data System (ADS)
Simon, M. Jose; Perez-Poch, Antoni; Ruiz, Xavier; Gavalda, Fina; Saez, Nuria
Since the pioneering works of Prof. Strughold in 1948, the aerospace medicine aimed to characterize the modifications induced in the human body by changes in the gravity level. In this respect, it is nowadays well known that one of the most serious problems of these kind of environments is the fluid shift. If this effect is enough severe and persistent, serious changes in the hemodynamic of the brain (cerebral blood flow and blood oxigenation level) appear which could be detected as alterations in the electroencephalogram, EEG [1]. Also, this fluid redistribution, together with the relocation of the heart in the thorax, induces detectable changes in the electrocardiogram, ECG [2]. Other kind of important problems are related with vestibular instability, kinetosis and illusory sensations. In particular since the seventies [3,4] it is known that in parabolic flights and due to eye movements triggered by the changing input from the otholith system, fixed real targets appeared to have moved downward while visual afterimages appeared to have moved upward (oculogravic illusions). In order to cover all the above-mentioned potential alterations, the present work, together with the gravity level, continuously monitors the electroencephalogram, EEG, the electrocardiogram, ECG and the electrooculogram, EOG of a normal subject trying to detect correlations between the different alterations observed in these signals and the changes of gravity during parabolic flights. The small aerobatic aircraft used is a CAP10B and during the flight the subject is located near the pilot. To properly cover all the range of accelerations we have used two sensitive triaxial accelerometers covering the high and low ranges of acceleration. Biosignals have been gathered using a Biopac data unit together with the Acknowledge software package (from BionicÔ). It is important to finally remark that, due to the obvious difference between the power of the different engines, the accelerometric characteristics of the aerobatic parabolic flights are different from the ones corresponding to the big Airbus-300 of Novespace-CNES-ESA aircraft. In this case, the two episodes of hypergravity reach 1.8g for 3 seconds with 20-25 seconds of low gravity in between whereas the small aerobatic plane reaches 3g level during roughly 2.5 seconds and 8 seconds period of low gravity. This means that the present potential alterations of the human body are more aggressive but also faster. [1] Y. Kawai, M. Doi, A. Setogawa, R. Shimoyama, K. Ueda, Y. Asai, K. Tatebayashi, Effects of Microgravity on Cerebral Hemodynamics, Yonago Acta Medica, 46 (2003) 1-8. [2] E.A.I. Aidu, V.G. Trunov, L.I. Titomir, A. Capderou, P. Vaďda, Transformation of Vectorcardiogram Due to Gravitation Alteration, Measurement, Science Review, 3 (2003) 29-32. [3] R.J. Von Baumgarten, G. Baldrighi, G.L. Schillinger, O. Harth, R. Thuemler, Vestibular function in the space environment, Acta Astronautica, 2 (1975) 49-58. [4] http://reversiblefigures.blogspot.com.es/p/outreach.html
Stability in terms of two measures for a class of semilinear impulsive parabolic equations
Dvirnyj, Aleksandr I; Slyn'ko, Vitalij I
2013-04-30
The problem of stability in terms of two measures is considered for semilinear impulsive parabolic equations. A new version of the comparison method is proposed, and sufficient conditions for stability in terms of two measures are obtained on this basis. An example of a hybrid impulsive system formed by a system of ordinary differential equations coupled with a partial differential equation of parabolic type is given. The efficiency of the described approaches is demonstrated. Bibliography: 24 titles.
McCabe, G.J., Jr.
1989-01-01
Errors of the Thornthwaite model can be analyzed using adjusted pan evaporation as an index of potential evapotranspiration. An examination of ratios of adjusted pan evaporation to Thornthwaite potential evapotranspiration indicates that the ratios are highest in the winter and lowest during summer months. This trend suggests a parabolic pattern. In this study a parabolic function is used to adjust Thornthwaite estimates of potential evapotranspiration. Forty locations east of the Rocky Mountains are analyzed. -from Author
V. K. Dobrev
2013-11-29
In the present paper we review the progress of the project of classification and construction of invariant differential operators for non-compact semisimple Lie groups. Our starting points is the class of algebras, which we called earlier 'conformal Lie algebras' (CLA), which have very similar properties to the conformal algebras of Minkowski space-time, though our aim is to go beyond this class in a natural way. For this we introduced recently the new notion of {\\it parabolic relation} between two non-compact semisimple Lie algebras $\\cal G$ and $\\cal G'$ that have the same complexification and possess maximal parabolic subalgebras with the same complexification. Thus, we consider the exceptional algebra $E_{7(7)}$ which is parabolically related to the CLA $E_{7(-25)}$. Other interesting examples are the orthogonal algebras $so(p,q)$ all of which are parabolically related to the conformal algebra $so(n,2)$ with $p+q=n+2$, the parabolic subalgebras including the Lorentz subalgebra $so(n-1,1)$ and its analogs $so(p-1,q-1)$. Further we consider the algebras $sl(2n,R)$ and for $n=2k$ the algebras $su^*(4k)$ which are parabolically related to the CLA $su(n,n)$. Further we consider the algebras $sp(r,r)$ which are parabolically related to the CLA $sp(2r,R)$. We consider also $E_{6(6)}$ and $E_{6(2)}$ which are parabolically related to the hermitian symmetric case $E_{6(-14)}$.
Asymptotic behaviour of the solutions of non-linear elliptic and parabolic systems in tube domains
Egorov, Yurii V; Kondrat'ev, V A; Oleinik, O A
1998-04-30
The paper is devoted to the study of the asymptotic behaviour of solutions of weakly non-linear elliptic and parabolic systems of second-order equations. In particular, the behaviour as t{yields}+{infinity} of the solution of a second-order non-linear parabolic equation satisfying a Neumann boundary condition at the boundary of a bounded Lipschitz domain is studied. The proofs are based on a result on the asymptotic equivalence of two systems of ordinary differential equations.
Iterative Methods for Solving Nonlinear Parabolic Problem in Pension Saving Management
NASA Astrophysics Data System (ADS)
Koleva, M. N.
2011-11-01
In this work we consider a nonlinear parabolic equation, obtained from Riccati like transformation of the Hamilton-Jacobi-Bellman equation, arising in pension saving management. We discuss two numerical iterative methods for solving the model problem—fully implicit Picard method and mixed Picard-Newton method, which preserves the parabolic characteristics of the differential problem. Numerical experiments for comparison the accuracy and effectiveness of the algorithms are discussed. Finally, observations are given.
NASA Astrophysics Data System (ADS)
Oladeinde, Mobolaji Humphrey; Akpobi, John Ajokpaoghene
2011-10-01
The hydrodynamic and magnetohydrodynamic (MHD) lubrication problem of infinitely wide inclined and parabolic slider bearings is solved numerically using the finite element method. The bearing configurations are discretized into three-node isoparametric quadratic elements. Stiffness integrals obtained from the weak form of the governing equations are solved using Gauss quadrature to obtain a finite number of stiffness matrices. The global system of equations obtained from enforcing nodal continuity of pressure for the bearings are solved using the Gauss-Seidel iterative scheme with a convergence criterion of 10-10. Numerical computations reveal that, when compared for similar profile and couple stress parameters, greater pressure builds up in a parabolic slider compared to an inclined slider, indicating a greater wedge effect in the parabolic slider. The parabolic slider bearing is also shown to develop a greater load capacity when lubricated with magnetic fluids. The superior performance of parabolic slider bearing is more pronounced at greater Hartmann numbers for identical bearing structural parameters. It is also shown that when load carrying capacity is the yardstick for comparison, the parabolic slider bearings are superior to the inclined bearings when lubricated with couple stress or magnetic lubricants.
Explicit nonlinear finite element geometric analysis of parabolic leaf springs under various loads.
Kong, Y S; Omar, M Z; Chua, L B; Abdullah, S
2013-01-01
This study describes the effects of bounce, brake, and roll behavior of a bus toward its leaf spring suspension systems. Parabolic leaf springs are designed based on vertical deflection and stress; however, loads are practically derived from various modes especially under harsh road drives or emergency braking. Parabolic leaf springs must sustain these loads without failing to ensure bus and passenger safety. In this study, the explicit nonlinear dynamic finite element (FE) method is implemented because of the complexity of experimental testing A series of load cases; namely, vertical push, wind-up, and suspension roll are introduced for the simulations. The vertical stiffness of the parabolic leaf springs is related to the vehicle load-carrying capability, whereas the wind-up stiffness is associated with vehicle braking. The roll stiffness of the parabolic leaf springs is correlated with the vehicle roll stability. To obtain a better bus performance, two new parabolic leaf spring designs are proposed and simulated. The stress level during the loadings is observed and compared with its design limit. Results indicate that the newly designed high vertical stiffness parabolic spring provides the bus a greater roll stability and a lower stress value compared with the original design. Bus safety and stability is promoted, as well as the load carrying capability. PMID:24298209
Dobrev, V K
2013-01-01
In the present paper we continue the project of systematic construction of invariant differential operators for non-compact semisimple Lie groups. Our starting points is the class of algebras, which we call 'conformal Lie algebras' (CLA), which have very similar properties to the conformal algebras of Minkowski space-time, though our aim is to go beyond this class in a natural way. For this we introduce the new notion of {\\it parabolic relation} between two non-compact semisimple Lie algebras g and g' that have the same complexification and possess maximal parabolic subalgebras with the same complexification. Thus, we consider the exceptional algebra E_{7(7)} which is parabolically related to the CLA E_{7(-25)}, the parabolic subalgebras including E_{6(6)} and E_{6(-6)} . Other interesting examples are the orthogonal algebras so(p,q) all of which are parabolically related to the conformal algebra so(n,2) with p+q=n+2, the parabolic subalgebras including the Lorentz subalgebra so(n-1,1) and its analogs so(p-1,...
Comparison of Parabolic Filtration Methods for 3D Filtered Back Projection in Pulsed EPR Imaging
Qiao, Zhiwei; Redler, Gage; Epel, Boris; Halpern, Howard J
2015-01-01
Pulse electron paramagnetic resonance imaging (Pulse EPRI) is a robust method for noninvasively measuring local oxygen concentrations in vivo. For 3D tomographic EPRI, the most commonly used reconstruction algorithm is filtered back projection (FBP), in which the parabolic filtration process strongly influences image quality. In this work, we designed and compared 7 parabolic filtration methods to reconstruct both simulated and real phantoms. To evaluate these methods, we designed 3 error criteria and 1 spatial resolution criterion. It was determined that the 2 point derivative filtration method and the two-ramp-filter method have unavoidable negative effects resulting in diminished spatial resolution and increased artifacts respectively. For the noiseless phantom the rectangular-window parabolic filtration method and sinc-window parabolic filtration method were found to be optimal, providing high spatial resolution and small errors. In the presence of noise, the 3 point derivative method and Hamming-window parabolic filtration method resulted in the best compromise between low image noise and high spatial resolution. The 3 point derivative method is faster than Hamming-window parabolic filtration method, so we conclude that the 3 point derivative method is optimal for 3D FBP. PMID:25314081
Explicit Nonlinear Finite Element Geometric Analysis of Parabolic Leaf Springs under Various Loads
Kong, Y. S.; Omar, M. Z.; Chua, L. B.; Abdullah, S.
2013-01-01
This study describes the effects of bounce, brake, and roll behavior of a bus toward its leaf spring suspension systems. Parabolic leaf springs are designed based on vertical deflection and stress; however, loads are practically derived from various modes especially under harsh road drives or emergency braking. Parabolic leaf springs must sustain these loads without failing to ensure bus and passenger safety. In this study, the explicit nonlinear dynamic finite element (FE) method is implemented because of the complexity of experimental testing A series of load cases; namely, vertical push, wind-up, and suspension roll are introduced for the simulations. The vertical stiffness of the parabolic leaf springs is related to the vehicle load-carrying capability, whereas the wind-up stiffness is associated with vehicle braking. The roll stiffness of the parabolic leaf springs is correlated with the vehicle roll stability. To obtain a better bus performance, two new parabolic leaf spring designs are proposed and simulated. The stress level during the loadings is observed and compared with its design limit. Results indicate that the newly designed high vertical stiffness parabolic spring provides the bus a greater roll stability and a lower stress value compared with the original design. Bus safety and stability is promoted, as well as the load carrying capability. PMID:24298209
Solar photovoltaic reflective trough collection structure
Anderson, Benjamin J.; Sweatt, William C.; Okandan, Murat; Nielson, Gregory N.
2015-11-19
A photovoltaic (PV) solar concentration structure having at least two troughs encapsulated in a rectangular parallelepiped optical plastic structure, with the troughs filled with an optical plastic material, the troughs each having a reflective internal surface and approximately parabolic geometry, and the troughs each including photovoltaic cells situated so that light impinging on the optical plastic material will be concentrated onto the photovoltaic cells. Multiple structures can be connected to provide a solar photovoltaic collection system that provides portable, efficient, low-cost electrical power.
Protective telescoping shield for solar concentrator
NASA Technical Reports Server (NTRS)
Argoud, M. J.; Walker, W. L.; Butler, L. V. (inventors)
1986-01-01
An apparatus is described for use with a solar concentrator such as a parabolic dish which concentrates sunlight onto a small opening of a solar receiver, for protecting the receiver in the event of a system failure that could cause concentrated sunlight to damage the receiver. The protective apparatus includes a structure which can be moved to a stowed position where it does not block sunlight, to a deployed position. In this position, the structure forms a tube which substantially completely surrounds an axis connecting the receiver opening to the center of the concentrator at locations between the receiver and the concentrator.
Evaluation of aerosolized medications during parabolic flight maneuvers
NASA Technical Reports Server (NTRS)
Lloyd, Charles W.; Martin, William J.; Gosbee, John
1991-01-01
The goal was to visually evaluate the effect gravity has on delivery of medications by the use of various aerosol devices. During parabolic flight the same four aerosols were retested as performed in studio ground tests. It appears that the Cetacaine spray and the Ventolin inhaler function without failure during all test. The pump spray (Nostril) appeared to function normally when the container was full, however it appeared to begin to fail to deliver a full mist with larger droplet size when the container was nearly empty. The simple hand spray bottle appeared to work when the container was full and performed progressively worse as the container was emptied. During Apollo flights, it was reported that standard spray bottles did not work well, however, they did not indicate why. It appears that we would also conclude that standard spray bottles do not function as well in zero gravity by failing to produce a normal mist spray. The standard spray bottle allowed the fluid to come out in a narrow fluid stream when held with the nozzle either level or slightly tilted upward.
Conservation Laws and Potential Symmetries of Linear Parabolic Equations
Roman O. Popovych; Michael Kunzinger; Nataliya M. Ivanova
2008-03-07
We carry out an extensive investigation of conservation laws and potential symmetries for the class of linear (1+1)-dimensional second-order parabolic equations. The group classification of this class is revised by employing admissible transformations, the notion of normalized classes of differential equations and the adjoint variational principle. All possible potential conservation laws are described completely. They are in fact exhausted by local conservation laws. For any equation from the above class the characteristic space of local conservation laws is isomorphic to the solution set of the adjoint equation. Effective criteria for the existence of potential symmetries are proposed. Their proofs involve a rather intricate interplay between different representations of potential systems, the notion of a potential equation associated with a tuple of characteristics, prolongation of the equivalence group to the whole potential frame and application of multiple dual Darboux transformations. Based on the tools developed, a preliminary analysis of generalized potential symmetries is carried out and then applied to substantiate our construction of potential systems. The simplest potential symmetries of the linear heat equation, which are associated with single conservation laws, are classified with respect to its point symmetry group. Equations possessing infinite series of potential symmetry algebras are studied in detail.
Upwind algorithm for the parabolized Navier-Stokes equations
NASA Technical Reports Server (NTRS)
Lawrence, Scott L.; Tannehill, John C.; Chausee, Denny S.
1989-01-01
A new upwind algorithm based on Roe's scheme has been developed to solve the two-dimensional parabolized Navier-Stokes equations. This method does not require the addition of user-specified smoothing terms for the capture of discontinuities such as shock waves. Thus, the method is easy to use and can be applied without modification to a wide variety of supersonic flowfields. The advantages and disadvantages of this adaptation are discussed in relation to those of the conventional Beam-Warming (1978) scheme in terms of accuracy, stability, computer time and storage requirements, and programming effort. The new algorithm has been validated by applying it to three laminar test cases, including flat-plate boundary-layer flow, hypersonic flow past a 15-deg compression corner, and hypersonic flow into a converging inlet. The computed results compare well with experiment and show a dramatic improvement in the resolution of flowfield details when compared with results obtained using the conventional Beam-Warming algorithm.
Investigation of reliability attributes and accelerated stress factors on terrestrial solar cells
NASA Technical Reports Server (NTRS)
Lathrop, J. W.
1982-01-01
The accelerated stress test results obtained on all terrestrial solar cells since the inception of the program are summarized. Tested cells were grouped according to the method used to form the conductive metallization layer: solder dipped, vacuum deposited, screen printed, and copper plated. Although metallization systems within each group were quite similar, they differed in numerous details according to the procedures employed by each manufacturer. Test results were summarized for all cells according to both electrical degradation and catastrophic mechanical changes. These results indicated a variability within each metallization category which was dependent on the manufacturer. Only one manufacturer was represented in the copper plated category and, although these showed no signs of detrimental copper diffusion during high temperature testing, their metallization was removed easily during high humidity pressure cooker testing. Preliminary testing of encapsulated cells showed no major differences between encapsulated and unencapsulated cells when subjected to accelerated testing.
Pasteurization of naturally contaminated water with solar energy.
Ciochetti, D A; Metcalf, R H
1984-01-01
A solar box cooker (SBC) was constructed with a cooking area deep enough to hold several 3.7-liter jugs of water, and this was used to investigate the potential of using solar energy to pasteurize naturally contaminated water. When river water was heated either in the SBC or on a hot plate, coliform bacteria were inactivated at temperatures of 60 degrees C or greater. Heating water in an SBC to at least 65 degrees C ensures that the water will be above the milk pasteurization temperature of 62.8 degrees C for at least an hour, which appears sufficient to pasteurize contaminated water. On clear or partly cloudy days, with the SBC facing magnetic south in Sacramento, bottom water temperatures of at least 65 degrees C could be obtained in 11.1 liters of water during the 6 weeks on either side of the summer solstice, in 7.4 liters of water from mid-March through mid-September, and in 3.7 liters of water an additional 2 to 3 weeks at the beginning and end of the solar season. Periodic repositioning of the SBC towards the sun, adjusting the back reflective lid, and preheating water in a simple reflective device increased final water temperatures. Simultaneous cooking and heating water to pasteurizing temperatures was possible. Additional uses of the SBC to pasteurize soil and to decontaminate hospital materials before disposal in remote areas are suggested. PMID:6712206
Cluster eye camera using microlenses on parabolic surface
NASA Astrophysics Data System (ADS)
Shen, Hui-Kai; Su, Guo-Dung J.
2013-10-01
There are two main types of imaging systems that exist in nature: the single aperture eye and the compound eye. Usually, cameras and most of artificial imaging systems are similar to the single aperture eye. But compound lenses can be more compact than single lenses. Our design is based on insect compound eyes, which also have a wide field of view (FOV). With the rise of micro-optical techniques, fabricating compound lenses has become easier. The simplest form of a curved microlens array is a parabolic surface. In this paper, we proposed a multi-channel imaging system, which combines the principles of the insect compound eye and the human eye. The optical system enables the reduction of track length of the imaging optics to achieve miniaturization. With the aid of optical engineering software ZEMAX, the multi-channel structure is simulated by a curved microlens array, and we use a Hypergon lens as the main lens to simulate the human eye, which can achieve the purpose of the wide FOV. With this architecture, each microlens of a microlens array transmits a segment of the overall FOV. The partial images that are separately recorded in different channels are stitched together to form the final image of the whole FOV by software processing. A 2.74 mm thin imaging system with 59 channels and 90° FOV is optimized using ZEMAX sequential ray tracing software on a 6.16 mm × 4.62 mm image plane. Finally, we will discuss the simulation results of this system and compare it with the optical cluster eye system and a mobile phone patent.
NASA Technical Reports Server (NTRS)
Latta, A. F.; Bowyer, J. M.; Fujita, T.
1979-01-01
This paper presents the performance and cost of four 10-MWe advanced solar thermal electric power plants sited in various regions of the continental United States. Each region has different insolation characteristics which result in varying collector field areas, plant performance, capital costs, and energy costs. The paraboloidal dish, central receiver, cylindrical parabolic trough, and compound parabolic concentrator (CPC) comprise the advanced concepts studied. This paper contains a discussion of the regional insolation data base, a description of the solar systems' performances and costs, and a presentation of a range for the forecast cost of conventional electricity by region and nationally over the next several decades.
Luo, Jun
2014-08-08
component failures and their effect on plant engineering and financial performance, and to conduct an analysis to predict energy payback. The results show some fundamental conclusions. First, the electricity production could be improved by adjusting plant...
Reducing the Cost of Thermal Energy Storage for Parabolic Trough Solar Power Plants
Gawlik, Keith
2013-06-25
Thermal energy storage systems using phase change materials were evaluated for trough systems that use oil, steam, and high temperature salts as heat transfer fluids. A variety of eutectic salts and metal alloys were considered as phase change materials in a cascaded arrangement. Literature values of specific heat, latent heat, density, and other thermophysical properties were used in initial analyses. Testing laboratories were contracted to measure properties for candidate materials for comparison to the literature and for updating the models. A TRNSYS model from Phase 1 was further developed for optimizing the system, including a novel control algorithm. A concept for increasing the bulk thermal conductivity of the phase change system was developed using expanded metal sheets. Outside companies were contracted to design and cost systems using platecoil heat exchangers immersed in the phase change material. Laboratory evaluations of the one-dimensional and three-dimensional behavior of expanded metal sheets in a low conductivity medium were used to optimize the amount of thermal conductivity enhancement. The thermal energy storage systems were compared to baseline conventional systems. The best phase change system found in this project, which was for the high temperature plant, had a projected cost of $25.2 per kWhth, The best system also had a cost that was similar to the base case, a direct two-tank molten salt system.
Some integral representations and limits for (products of) the parabolic cylinder function
Dirk Veestraeten
2015-05-26
Veestraeten [1] recently derived inverse Laplace transforms for Laplace transforms that contain products of two parabolic cylinder functions by exploiting the link between the parabolic cylinder function and the transition density and distribution functions of the Ornstein-Uhlenbeck process. This paper first uses these results to derive new integral representations for (products of two) parabolic cylinder functions. Second, as the Brownian motion process with drift is a limiting case of the Ornstein-Uhlenbeck process also limits can be calculated for the product of gamma functions and (products of) parabolic cylinder functions. The central results in both cases contain, in stylised form, D_{v}(x)D_{v}(y) and D_{v}(x)D_{v-1}(y) such that the recurrence relation of the parabolic cylinder function straightforwardly allows to obtain integral representations and limits also for countless other combinations in the orders such as D_{v}(x)D_{v-3}(y) and D_{v+1}(x)D_{v}(y).
Interband magneto-spectroscopy in InSb square and parabolic quantum wells
Kasturiarachchi, T.; Edirisooriya, M.; Mishima, T. D.; Doezema, R. E.; Santos, M. B.; Saha, D.; Pan, X.; Sanders, G. D.; Stanton, C. J.
2015-06-07
We measure the magneto-optical absorption due to intersubband optical transitions between conduction and valence subband Landau levels in InSb square and parabolic quantum wells. InSb has the narrowest band gap (0.24?eV at low temperature) of the III–V semiconductors leading to a small effective mass (0.014 m{sub 0}) and a large g–factor (?51). As a result, the Landau level spacing is large at relatively small magnetic fields (<8?T), and one can observe spin-splitting of the Landau levels. We examine two structures: (i) a multiple-square-well structure and (ii) a structure containing multiple parabolic wells. The energies and intensities of the strongest features are well explained by a modified Pidgeon-Brown model based on an 8-band k•p model that explicitly incorporates pseudomorphic strain. The strain is essential for obtaining agreement between theory and experiment. While modeling the square well is relatively straight-forward, the parabolic well consists of 43 different layers of various thickness to approximate a parabolic potential. Agreement between theory and experiment for the parabolic well validates the applicability of the model to complicated structures, which demonstrates the robustness of our model and confirms its relevance for developing electronic and spintronic devices that seek to exploit the properties of the InSb band structure.
Dobrev, V K
2013-01-01
In the present paper we review the progress of the project of classification and construction of invariant differential operators for non-compact semisimple Lie groups. Our starting points is the class of algebras, which we called earlier 'conformal Lie algebras' (CLA), which have very similar properties to the conformal algebras of Minkowski space-time, though our aim is to go beyond this class in a natural way. For this we introduced recently the new notion of {\\it parabolic relation} between two non-compact semisimple Lie algebras $\\cal G$ and $\\cal G'$ that have the same complexification and possess maximal parabolic subalgebras with the same complexification. Thus, we consider the exceptional algebra $E_{7(7)}$ which is parabolically related to the CLA $E_{7(-25)}$. Other interesting examples are the orthogonal algebras $so(p,q)$ all of which are parabolically related to the conformal algebra $so(n,2)$ with $p+q=n+2$, the parabolic subalgebras including the Lorentz subalgebra $so(n-1,1)$ and its analogs ...
Cassegrainian concentrator solar array exploratory development module
NASA Technical Reports Server (NTRS)
Patterson, R. E.; Crabtree, W. L.
1982-01-01
A miniaturized Cassegrainian concentrator solar array concept is under development to reduce the cost of multi-kW spacecraft solar arrays. A primary parabolic reflector directs incoming solar energy to a secondary, centrally mounted inverted hyperbolic reflector and down onto a solar cell mounted on an Mo heat spreader on a 0.25 mm thick Al heat fin. Each unit is 12.7 mm thick, which makes the concentrator assembly roughly as thick as a conventional panel. The output is 100 W/sq and 20 W/kg, considering 20% efficient Si cells at 100 suns. A tertiary light catcher is mounted around the cell to ameliorate optic errors. The primary reflector is electroformed Ni with protective and reflective coatings. The cells have back surface reflectors and a SiO antireflective coating. An optical efficiency of 80% is projected, and GaAs cells are being considered in an attempt to raise cell efficiencies to over 30%.
High performance solar Stirling system
NASA Technical Reports Server (NTRS)
Stearns, J. W.; Haglund, R.
1981-01-01
A full-scale Dish-Stirling system experiment, at a power level of 25 kWe, has been tested during 1981 on the Test Bed Concentrator No. 2 at the Parabolic Dish Test Site, Edwards, CA. Test components, designed and developed primarily by industrial contractors for the Department of Energy, include an advanced Stirling engine driving an induction alternator, a directly-coupled solar receiver with a natural gas combustor for hybrid operation and a breadboard control system based on a programmable controller and standard utility substation components. The experiment demonstrated practicality of the solar Stirling application and high system performance into a utility grid. This paper describes the design and its functions, and the test results obtained.
Influence of refractive index and solar concentration on optical power absorption in slabs
NASA Technical Reports Server (NTRS)
Williams, M. D.
1988-01-01
The optical power absorbed by a slab at the focus of a parabolic dish concentrator is calculated. The calculations are plotted versus maximum angle of incidence of irradiation (which corresponds to solar concentration) with absorption coefficient as a parameter for several different indices of refraction that represent real materials.
Solar energy system design: A simple method for sizing the collector field and thermal storage
NASA Astrophysics Data System (ADS)
Peters, R. R.
1981-07-01
The Zero Marginal Cost (ZMC) technique to enable quick, accurate designs of parabolic trough solar energy systems was developed. The ZMC technique is discussed and it is shown that systems designed with this technique compare quite favorably with those designed using expensive computer codes.
NASA Technical Reports Server (NTRS)
Rosner, Robert; Noyes, Robert; Antiochos, Spiro K.; Canfield, Richard C.; Chupp, Edward L.; Deming, Drake; Doschek, George A.; Dulk, George A.; Foukal, Peter V.; Gilliland, Ronald L.
1991-01-01
An overview is given of modern solar physics. Topics covered include the solar interior, the solar surface, the solar atmosphere, the Large Earth-based Solar Telescope (LEST), the Orbiting Solar Laboratory, the High Energy Solar Physics mission, the Space Exploration Initiative, solar-terrestrial physics, and adaptive optics. Policy and related programmatic recommendations are given for university research and education, facilitating solar research, and integrated support for solar research.
NASA Astrophysics Data System (ADS)
Yan, Na; Baas, Andreas
2015-04-01
Parabolic dunes are one of a few common aeolian landforms which are highly controlled by eco-geomorphic interactions. Parabolic dunes, on the one hand, can be developed from highly mobile dune landforms, barchans for instance, in an ameliorated vegetation condition; or on the other hand, they can be reactivated and transformed back into mobile dunes due to vegetation deterioration. The fundamental mechanisms and eco-geomorphic interactions controlling both dune transformations remain poorly understood. To bridge the gap between complex processes involved in dune transformations on a relatively long temporal scale and real world monitoring records on a very limited temporal scale, this research has extended the DECAL model to incorporate 'dynamic' growth functions and the different 'growth' of perennial shrubs between growing and non-growing seasons, informed by field measurements and remote sensing analysis, to explore environmental controls and eco-geomorphic interactions of both types of dune transformation. A non-dimensional 'dune stabilising index' is proposed to capture the interactions between environmental controls (i.e. the capabilities of vegetation to withstand wind erosion and sand burial, the sandy substratum thickness, the height of the initial dune, and the sand transport potential), and establish the linkage between these controls and the geometry of a stabilising dune. An example demonstrates how to use the power-law relationship between the dune stabilising index and the normalised migration distance to assist in extrapolating the historical trajectories of transforming dunes. The modelling results also show that a slight increase in vegetation cover of an initial parabolic dune can significantly increase the reactivation threshold of climatic impact (both drought stress and wind strength) required to reactivate a stabilising parabolic dune into a barchan. Four eco-geomorphic interaction zones that govern a barchan-to-parabolic dune transformation and a parabolic-to-barchan dune transformation have been identified. These zones exhibit different characteristics and dynamics that are sensitive to changes in environmental forces, and can be potentially used as a proxy to monitor the mobility of a dune system.
Bouri, C.; Selles, P.; Malegat, L.; Kwato Njock, M. G.
2006-09-15
Spherical and parabolic partial cross sections and asymmetry parameters, defined in the ejected electron frame, are presented for photoionization excitation of the helium atom at 0.1 eV above its double ionization threshold. A quantitative law giving the dominant spherical partial wave l{sub dom} for each excitation level n is obtained. The parabolic partial cross sections are shown to satisfy the same approximate selection rules as the related Rydberg series of doubly excited states (K,T){sub n}{sup A}. The analysis of radial and angular correlations reveals the close relationship between double excitation, ionization excitation, and double ionization. Opposite to a widespread belief, the observed value of the asymmetry parameter is shown to result from the interplay of radial correlations and symmetry constraints, irrespective of angular correlations. Finally, the measurement of parabolic partial cross sections is proposed as a challenge to experimentalists.
Observation of spectral self-imaging by nonlinear parabolic cross-phase modulation.
Lei, Lei; Huh, Jeonghyun; Cortés, Luis Romero; Maram, Reza; Wetzel, Benjamin; Duchesne, David; Morandotti, Roberto; Azańa, José
2015-11-15
We report an experimental demonstration of spectral self-imaging on a periodic frequency comb induced by a nonlinear all-optical process, i.e., parabolic cross-phase modulation in a highly nonlinear fiber. The comb free spectral range is reconfigured by simply tuning the temporal period of the pump parabolic pulse train. In particular, undistorted FSR divisions by factors of 2 and 3 are successfully performed on a 10 GHz frequency comb, realizing new frequency combs with an FSR of 5 and 3.3 GHz, respectively. The pump power requirement associated to the SSI phenomena is also shown to be significantly relaxed by the use of dark parabolic pulses. PMID:26565885
The heat-balance integral: 1. How to calibrate the parabolic profile?
NASA Astrophysics Data System (ADS)
Hristov, Jordan
The Heat-Balance Integral Method (HBIM) of Goodman under classic prescribed temperature boundary conditions has been studied towards it optimization. Because the parabolic profile satisfies both the boundary conditions and the heat-balance integral at any value of the exponent the calibration is of a primary importance in generation of the approximate solution. The simple 1-D heat conduction problem, enabling one to demonstrate the HBIM performance with the entropy generation minimization (EGM) concept in calibration of a parabolic temperature profile with unspecified exponents, has been developed. The EGM concept provides constraints that impose addition boundary conditions at the approximate parabolic profile. Additionally, entire domain optimizations based on the mean-squared error concept has been performed in two versions - the method Myers and through a similarity transformed diffusion equation.
Wind load design methods for ground-based heliostats and parabolic dish collectors
Peterka, J A; Derickson, R G
1992-09-01
The purpose of this design method is to define wind loads on flat heliostat and parabolic dish collectors in a simplified form. Wind loads are defined for both mean and peak loads accounting for the protective influence of upwind collectors, wind protective fences, or other wind-blockage elements. The method used to define wind loads was to generalize wind load data obtained during tests on model collectors, heliostats or parabolic dishes, placed in a modeled atmospheric wind in a boundary-layer wind-tunnel at Colorado State University. For both heliostats and parabolic dishes, loads are reported for solitary collectors and for collectors as elements of a field. All collectors were solid with negligible porosity; thus the effects of porosity in the collectors is not addressed.
A parabolic analogue of the higher-order comparison theorem of De Silva and Savin
NASA Astrophysics Data System (ADS)
Banerjee, Agnid; Garofalo, Nicola
2016-01-01
We show that the quotient of two caloric functions which vanish on a portion of the lateral boundary of a H k + ? domain is H k + ? up to the boundary for k ? 2. In the case k = 1, we show that the quotient is in H 1 + ? if the domain is assumed to be space-time C 1, ? regular. This can be thought of as a parabolic analogue of a recent important result in [8], and we closely follow the ideas in that paper. We also give counterexamples to the fact that analogous results are not true at points on the parabolic boundary which are not on the lateral boundary, i.e., points which are at the corner and base of the parabolic boundary.
UPC BarcelonaTech Platform. Innovative aerobatic parabolic flights for life sciences experiments.
NASA Astrophysics Data System (ADS)
Perez-Poch, Antoni; Gonzalez, Daniel
We present an innovative method of performing parabolic flights with aerobatic single-engine planes. A parabolic platform has been established in Sabadell Airport (Barcelona, Spain) to provide an infraestructure ready to allow Life Sciences reduced gravity experiments to be conducted in parabolic flights. Test flights have demonstrated that up to 8 seconds of reduced gravity can be achieved by using a two-seat CAP10B aircraft, with a gravity range between 0.1 and 0.01g in the three axis. A parabolic flight campaign may be implemented with a significant reduction in budget compared to conventional parabolic flight campaigns, and with a very short time-to-access to the platform. Operational skills and proficiency of the pilot controling the aircraft during the maneuvre, sensitivity to wind gusts, and aircraft balance are the key issues that make a parabola successful. Efforts are focused on improving the total “zero-g” time and the quality of reduced gravity achieved, as well as providing more space for experiments. We report results of test flights that have been conducted in order to optimize the quality and total microgravity time. A computer sofware has been developed and implemented to help the pilot optimize his or her performance. Finally, we summarize the life science experiments that have been conducted in this platform. Specific focus is given to the very successful 'Barcelona ZeroG Challenge', this year in its third edition. This educational contest gives undergraduate and graduate students worldwide the opportunity to design their research within our platform and test it on flight, thus becoming real researchers. We conclude that aerobatic parabolic flights have proven to be a safe, unexpensive and reliable way to conduct life sciences reduced gravity experiments.
Similarity and generalized finite-difference solutions of parabolic partial differential equations.
NASA Technical Reports Server (NTRS)
Clausing, A. M.
1971-01-01
Techniques are presented for obtaining generalized finite-difference solutions to partial differential equations of the parabolic type. It is shown that the advantages of similarity in the solution of similar problems are generally not lost if the solution to the original partial differential equations is effected in the physical plane by finite-difference methods. The analysis results in a considerable saving in computational effort in the solution of both similar and nonsimilar problems. Several examples, including both the heat-conduction equation and the boundary-layer equations, are given. The analysis also provides a practical means of estimating the accuracy of finite-difference solutions to parabolic equations.
NASA Technical Reports Server (NTRS)
Vernalis, Marina N.; Latham, Ricky D.; Fanton, John W.; Geffney, F. Andrew
1993-01-01
Transthoracic echocardiography (TTE) is a feasible method to noninvasively examine cardiac anatomy during parabolic flight. However, transducer placement on the chest wall is very difficult to maintain during transition to microgravity. In addition, TTE requires the use of low frequency transponders which limit resolution. Transesophical echocardiography (TEE) is an established imaging technique which obtains echocardiographic information from the esophagus. It is a safe procedure and provides higher quality images of cardiac structure than obtained with TTE. This study is designed to determine whether TEE was feasible to perform during parabolic flight and to determine whether acute central volume responses occur in acute transition to zero gravity by direct visualization of the cardiac chambers.
NASA Technical Reports Server (NTRS)
Litvin, Faydor L.; Lee, Hong-Tao
1989-01-01
A new approach for determination of machine-tool settings for spiral bevel gears is proposed. The proposed settings provide a predesigned parabolic function of transmission errors and the desired location and orientation of the bearing contact. The predesigned parabolic function of transmission errors is able to absorb piece-wise linear functions of transmission errors that are caused by the gear misalignment and reduce gear noise. The gears are face-milled by head cutters with conical surfaces or surfaces of revolution. A computer program for simulation of meshing, bearing contact and determination of transmission errors for misaligned gear has been developed.
Erlangen Program at Large--2: Inventing a wheel. The parabolic one
Vladimir V. Kisil
2007-07-27
We discuss parabolic versions of Euler's identity e^{it}=cos t + i sin t. A purely algebraic approach based on dual numbers is known to produce a very trivial relation e^{pt} = 1+pt. Therefore we use a geometric setup of parabolic rotations to recover the corresponding non-trivial algebraic framework. Our main tool is Moebius transformations which turn out to be closely related to induced representations of the group SL(2,R). Keywords: complex numbers, dual numbers, double numbers, linear algebra, invariant, computer algebra, GiNaC
Well-Posedness of Nonlocal Parabolic Differential Problems with Dependent Operators
Ashyralyev, Allaberen; Hanalyev, Asker
2014-01-01
The nonlocal boundary value problem for the parabolic differential equation v'(t) + A(t)v(t) = f(t)??(0 ? t ? T), v(0) = v(?) + ?, 0 < ? ? T in an arbitrary Banach space E with the dependent linear positive operator A(t) is investigated. The well-posedness of this problem is established in Banach spaces C0?,?(E???) of all E???-valued continuous functions ?(t) on [0, T] satisfying a Hölder condition with a weight (t + ?)?. New Schauder type exact estimates in Hölder norms for the solution of two nonlocal boundary value problems for parabolic equations with dependent coefficients are established. PMID:24526903
Solar Thermal Electricity Generating System
NASA Astrophysics Data System (ADS)
Mishra, Sambeet; Tripathy, Pratyasha
2012-08-01
A Solar Thermal Electricity generating system also known as Solar Thermal Power plant is an emerging renewable energy technology, where we generate the thermal energy by concentrating and converting the direct solar radiationat medium/high temperature (300?C ń 800?C). The resulting thermal energy is then used in a thermodynamic cycleto produce electricity, by running a heat engine, which turns a generator to make electricity. Solar thermal power is currently paving the way for the most cost-effective solar technology on a large scale and is heading to establish a cleaner, pollution free and secured future. Photovoltaic (PV) and solar thermal technologies are two main ways of generating energy from the sun, which is considered the inexhaustible source of energy. PV converts sunlight directly into electricity whereas in Solar thermal technology, heat from the sun's rays is concentrated to heat a fluid, whose steam powers a generator that produces electricity. It is similar to the way fossil fuel-burning power plants work except that the steam is produced by the collected heat rather than from the combustion of fossil fuels. In order to generate electricity, five major varieties of solar thermal technologies used are:* Parabolic Trough Solar Electric Generating System (SEGS).* Central Receiver Power Plant.* Solar Chimney Power Plant.* Dish Sterling System.* Solar Pond Power Plant.Most parts of India,Asia experiences a clear sunny weather for about 250 to 300 days a year, because of its location in the equatorial sun belt of the earth, receiving fairly large amount of radiation as compared to many parts of the world especially Japan, Europe and the US where development and deployment of solar technologies is maximum.Whether accompanied with this benefit or not, usually we have to concentrate the solar radiation in order to compensate for the attenuation of solar radiation in its way to earthís surface, which results in from 63,2 GW/m2 at the Sun to 1 kW/m2 at EarthĄs surface. The higher the concentration, the higher the temperatures we can achieve when converting solar radiation into thermal energy
Rankline-Brayton engine powered solar thermal aircraft
Bennett, Charles L. (Livermore, CA)
2012-03-13
A solar thermal powered aircraft powered by heat energy from the sun. A Rankine-Brayton hybrid cycle heat engine is carried by the aircraft body for producing power for a propulsion mechanism, such as a propeller or other mechanism for enabling sustained free flight. The Rankine-Brayton engine has a thermal battery, preferably containing a lithium-hydride and lithium mixture, operably connected to it so that heat is supplied from the thermal battery to a working fluid. A solar concentrator, such as reflective parabolic trough, is movably connected to an optically transparent section of the aircraft body for receiving and concentrating solar energy from within the aircraft. Concentrated solar energy is collected by a heat collection and transport conduit, and heat transported to the thermal battery. A solar tracker includes a heliostat for determining optimal alignment with the sun, and a drive motor actuating the solar concentrator into optimal alignment with the sun based on a determination by the heliostat.
Rankine-Brayton engine powered solar thermal aircraft
Bennett, Charles L. (Livermore, CA)
2009-12-29
A solar thermal powered aircraft powered by heat energy from the sun. A Rankine-Brayton hybrid cycle heat engine is carried by the aircraft body for producing power for a propulsion mechanism, such as a propeller or other mechanism for enabling sustained free flight. The Rankine-Brayton engine has a thermal battery, preferably containing a lithium-hydride and lithium mixture, operably connected to it so that heat is supplied from the thermal battery to a working fluid. A solar concentrator, such as reflective parabolic trough, is movably connected to an optically transparent section of the aircraft body for receiving and concentrating solar energy from within the aircraft. Concentrated solar energy is collected by a heat collection and transport conduit, and heat transported to the thermal battery. A solar tracker includes a heliostat for determining optimal alignment with the sun, and a drive motor actuating the solar concentrator into optimal alignment with the sun based on a determination by the heliostat.
Acrylic solar energy reflecting film 3M brand ECP-244 (formerly FEK-244)
Benson, B.A.
1983-06-01
A highly specular aluminized acrylic film 3M BRAND ECP-244, is discussed regarding its utilization as a solar energy reflector. ECP-244 is currently in use on over 30 parabolic trough installations throughout the U.S., totaling approximately 500,000 ft./sup 2/. Also discussed, is its use on the worlds largest parabolic dish installation at Shenandoah, GA. The properties, application methods, design considerations and maintenance of this acrylic film are reviewed, along with field measurements on percent reflectivity of trough installations up to 6-1/2 years old.
Utility-Scale Concentrating Solar Power and Photovoltaic Projects: A Technology and Market Overview
Mendelsohn, M.; Lowder, T.; Canavan, B.
2012-04-01
Over the last several years, solar energy technologies have been, or are in the process of being, deployed at unprecedented levels. A critical recent development, resulting from the massive scale of projects in progress or recently completed, is having the power sold directly to electric utilities. Such 'utility-scale' systems offer the opportunity to deploy solar technologies far faster than the traditional 'behind-the-meter' projects designed to offset retail load. Moreover, these systems have employed significant economies of scale during construction and operation, attracting financial capital, which in turn can reduce the delivered cost of power. This report is a summary of the current U.S. utility-scale solar state-of-the-market and development pipeline. Utility-scale solar energy systems are generally categorized as one of two basic designs: concentrating solar power (CSP) and photovoltaic (PV). CSP systems can be further delineated into four commercially available technologies: parabolic trough, central receiver (CR), parabolic dish, and linear Fresnel reflector. CSP systems can also be categorized as hybrid, which combine a solar-based system (generally parabolic trough, CR, or linear Fresnel) and a fossil fuel energy system to produce electric power or steam.
Simple Verification of the Parabolic Shape of a Rotating Liquid and a Boat on Its Surface
ERIC Educational Resources Information Center
Sabatka, Z.; Dvorak, L.
2010-01-01
This article describes a simple and inexpensive way to create and to verify the parabolic surface of a rotating liquid. The liquid is water. The second part of the article deals with the problem of a boat on the surface of a rotating liquid. (Contains 1 table, 10 figures and 5 footnotes.)
Approximation Methods for Inverse Problems Governed by Nonlinear Parabolic Systems \\Lambda
the convergence are given for a model of dioxin uptake and elimination in a distributed liver model address: U.S. Environmental Protection Agency, National Health and Environmental Effects Research by nonlinear parabolic partial differential equations with delays. Motivated by a concrete example for dioxin
Well-posedness and Regularity for a Parabolic-Hyperbolic Penrose-Fife Phase Field
Rocca, Elisabetta
Well-posedness and Regularity for a Parabolic-Hyperbolic Penrose-Fife Phase Field System Elisabetta from the Penrose-Fife approach to the kinetics of phase-transitions. The system couples a nonlinear-hyperbolic model to the weak solution of the standard Penrose-Fife model as Âµ 0. However, the main novelty
Stability of shock waves for multi-dimensional hyperbolic-parabolic conservation laws
NASA Astrophysics Data System (ADS)
Li, Dening
1988-01-01
The uniform linear stability of shock waves is considerd for quasilinear hyperbolic-parabolic coupled conservation laws in multi-dimensional space. As an example, the stability condition and its dynamic meaning for isothermal shock wave in radiative hydrodynamics are analyzed.
NASA Technical Reports Server (NTRS)
Lashmet, P. K.; Woodrow, P. T.
1975-01-01
Numerical instabilities often arise in the use of high-ordered collocation approximations for numerically solving parabolic partial differential equations. These problems may be reduced by formulations involving evaluation of collocation polynomials rather than combination of the polynomials into a power series. As an illustration, two formulations using shifted Legendre polynomials of order 26 and less are compared.
On the Hoelder regularity for parabolic quasivariational inequalities of impulse control
Tregub, V.L.
1995-12-05
For arbitrary generalized solutions of parabolic impulse control problems, a local estimate of the Holder norms is obtained. The boundedness of the Holder norms of solutions subject to the Neumann boundary condition is proved. The results are established under the same hypotheses as in the classical problems.
Self-similar intermediate asymptotics for a degenerate parabolic filtration-absorption equation
Chertock, Alina
Self-similar intermediate asymptotics for a degenerate parabolic filtration-absorption equation G as a model of the groundwater flow in a water-absorbing fissurized porous rock; therefore, we refer to this equation as a filtration-absorption equation. A family of self-similar solutions to this equation
Quantum Mechanics of Damped Systems II. Damping and Parabolic Potential Barrier.
Quantum Mechanics of Damped Systems II. Damping and Parabolic Potential Barrier. Dariusz Chru#19 also as inverted or reversed oscillator. They correspond to the poles of meromorphic continuation10. Key words: quantum mechanics, distributions, spectral theorem, Gel'fand triplets. 1 Introduction
Quasilinear parabolic variational inequalities with multi-valued lower-order terms
NASA Astrophysics Data System (ADS)
Carl, Siegfried; Le, Vy K.
2014-10-01
In this paper, we provide an analytical frame work for the following multi-valued parabolic variational inequality in a cylindrical domain : Find and an such that where is some closed and convex subset, A is a time-dependent quasilinear elliptic operator, and the multi-valued function is assumed to be upper semicontinuous only, so that Clarke's generalized gradient is included as a special case. Thus, parabolic variational-hemivariational inequalities are special cases of the problem considered here. The extension of parabolic variational-hemivariational inequalities to the general class of multi-valued problems considered in this paper is not only of disciplinary interest, but is motivated by the need in applications. The main goals are as follows. First, we provide an existence theory for the above-stated problem under coercivity assumptions. Second, in the noncoercive case, we establish an appropriate sub-supersolution method that allows us to get existence, comparison, and enclosure results. Third, the order structure of the solution set enclosed by sub-supersolutions is revealed. In particular, it is shown that the solution set within the sector of sub-supersolutions is a directed set. As an application, a multi-valued parabolic obstacle problem is treated.
Fast Time and Space Parallel Algorithms for Solution of Parabolic Partial Differential Equations
NASA Technical Reports Server (NTRS)
Fijany, Amir
1993-01-01
In this paper, fast time- and Space -Parallel agorithms for solution of linear parabolic PDEs are developed. It is shown that the seemingly strictly serial iterations of the time-stepping procedure for solution of the problem can be completed decoupled.
AN UNCONDITIONALLY STABLE SPLITTING SCHEME FOR A CLASS OF NONLINEAR PARABOLIC EQUATIONS
a tremendous activity on developing sophisticated numerical schemes (e.g., finite difference, finite element, finite volume, Godunov, and front tracking methods) that are designed to accurately capture discontinuousAN UNCONDITIONALLY STABLE SPLITTING SCHEME FOR A CLASS OF NONLINEAR PARABOLIC EQUATIONS KENNETH
Filbet, Francis
A finite volume scheme for nonlinear degenerate parabolic equations Marianne BESSEMOULIN-CHATARD and Francis FILBET April 15, 2013 Abstract We propose a second order finite volume scheme for nonlinear elements [4, 20, 29, 37, 38], cell-centered finite volume schemes [22, 23], vertex-centered finite volume
The Design of a Transmitter with a Parabolic Conical Reflector for a Sonar Ring Lindsay Kleeman
Ohya, Akihisa
The Design of a Transmitter with a Parabolic Conical Reflector for a Sonar Ring Lindsay Kleeman ARC@cs.tsukuba.ac.jp Abstract Sonar rings are composed of many ultrasonic receivers arranged in a ring and have in the past used. 1 Introduction SONAR (SOund NAvigation and Ranging) is a popular low cost sensor for mobile robotics
Second order estimates for Hessian equations of parabolic type on Riemannian manifolds
NASA Astrophysics Data System (ADS)
Jiao, Heming
2015-12-01
In this paper, we establish the second order estimates for solutions of the first initial-boundary value problem for general Hessian type fully nonlinear parabolic equations on Riemannian manifolds. The techniques used in this article can work for a wide range of fully nonlinear PDEs under very general conditions.
Dirk Veestraeten
2015-05-21
The Laplace transforms of the transition probability density and distribution functions for the Ornstein-Uhlenbeck process contain the product of two parabolic cylinder functions, namely D_{v}(x)D_{v}(y) and D_{v}(x)D_{v-1}(y), respectively. The inverse transforms of these products have as yet not been documented. However, the transition density and distribution functions can be obtained by alternatively applying Doob's transform to the Kolmogorov equation and casting the problem in terms of Brownian motion. Linking the resulting transition density and distribution functions to their Laplace transforms then specifies the inverse transforms to the aforementioned products of parabolic cylinder functions. These two results, the recurrence relation of the parabolic cylinder function and the properties of the Laplace transform then enable the calculation of inverse transforms also for countless other combinations in the orders of the parabolic cylinder functions such as D_{v}(x)D_{v-2}(y), D_{v+1}(x)D_{v-1}(y) and D_{v}(x)D_{v-3}(y).
Nuclear spin dynamics in parabolic quantum wells Ionel Tifrea* and Michael E. Flatte
Flatte, Michael E.
Nuclear spin dynamics in parabolic quantum wells Ionel T¸ifrea* and Michael E. Flatte´ Department March 2004 We present a detailed analytical and numerical analysis of the nuclear spin dynamics of the electronic wave function in small electric fields. The nuclear spin relaxation via the hyperfine interaction
Non-existence of solutions of semilinear parabolic differential inequalities in cones
Laptev, G G
2001-10-31
Problems of the non-existence of global non-trivial solutions of semilinear parabolic differential inequalities and second-order systems in cones are investigated. The proofs are based on the method of test functions and do not use comparison theorems or the maximum principle.
Abstract results on the ...nite extinction time property: application to a singular parabolic
Díaz, Jesús Ildefonso
Abstract results on the ...nite extinction time property: application to a singular parabolic by studying the ...nite extinction time for solutions of the abstract Cauchy problem ut +Au+Bu = 0 where bounded domain and Dirichlet boundary conditions. Key words. Finite extinction time for abstract Cauchy
NASA Astrophysics Data System (ADS)
Seo, Mansu; Park, Hana; Yoo, DonGyu; Jung, Youngsuk; Jeong, Sangkwon
Gauging the volume or mass of liquid propellant of a rocket vehicle in space is an important issue for its economic feasibility and optimized design of loading mass. Pressure-volume-temperature (PVT) gauging method is one of the most suitable measuring techniques in space due to its simplicity and reliability. This paper presents unique experimental results and analyses of PVT gauging method using liquid nitrogen under microgravity condition by parabolic flight. A vacuum-insulated and cylindrical-shaped liquid nitrogen storage tank with 9.2 L volume is manufactured by observing regulation of parabolic flight. PVT gauging experiments are conducted under low liquid fraction condition from 26% to 32%. Pressure, temperature, and the injected helium mass into the storage tank are measured to obtain the ullage volume by gas state equation. Liquid volume is finally derived by the measured ullage volume and the known total tank volume. Two sets of parabolic flights are conducted and each set is composed of approximately 10 parabolic flights. In the first set of flights, the short initial waiting time (3 ? 5 seconds) cannot achieve sufficient thermal equilibrium condition at the beginning. It causes inaccurate gauging results due to insufficient information of the initial helium partial pressure in the tank. The helium injection after 12 second waiting time at microgravity condition with high mass flow rate in the second set of flights achieves successful initial thermal equilibrium states and accurate measurement results of initial helium partial pressure. Liquid volume measurement errors in the second set are within 11%.
ON NONLINEAR VIBRATION OF NONUNIFORM BEAM WITH RECTANGULAR CROSS-SECTION AND PARABOLIC THICKNESS
Caruntu, Dumitru I. - Mechanical Engineering Department, University of Texas
ON NONLINEAR VIBRATION OF NONUNIFORM BEAM WITH RECTANGULAR CROSS-SECTION AND PARABOLIC THICKNESS tooth profile. It permits a nonlinear bending vibrations study (moderately large curvatures) of the gear results with Shaw and Pierre method. In this paper we study the nonlinear vibrations of nonuniform beam
Urbanski, Mariusz
ABSOLUTELY CONTINUOUS MEASURES WITH L q DENSITY ARISING FROM PARABOLIC IFS AND RANDOM CONTINUED.e. parameter value. Here we investigate when this measure has a density in L q , for q 2 (1; 2]. We prove continuous with L q density (see Theorem 3.3). If we assume that either the measure ÂŻ is an equilibrium
L q DENSITIES FOR MEASURES ASSOCIATED WITH PARABOLIC IFS WITH OVERLAPS
Urbanski, Mariusz
L q DENSITIES FOR MEASURES ASSOCIATED WITH PARABOLIC IFS WITH OVERLAPS B. SOLOMYAK AND M. URBA the projected measure does have a density in L q (R). The precise formulation is given in Section 3 (see continued fractions. Lyons [L] found a threshold parameter above which the measures cannot have a density
Effective Mass of Thermoelectric Materials with Non-Parabolic Kane Bands
NASA Astrophysics Data System (ADS)
Snyder, G. Jeffrey
2015-03-01
Effective mass is a concept commonly used to describe electronic transport in semiconductors using a classical analogy to the kinetic theory of gasses. We describe many important electronic transport parameters explicitly with an electronic band mass including: Density of states, charge carrier concentration, mobility, and in particular for thermoelectrics, the Seebeck coefficient. For systems with known electronic band structures these properties can be calculated leading to subtly different definitions of effective mass. In the free electron or parabolic band model the effective masses are the same and we use the term effective mass interchangably. However the differences between these defintions or uses of effective mass become apparent in non-parabolic band structures where it is desirable to describe the transport in terms of a effective mass that changes with energy (or Fermi Level). For example Kane bands, which become more linear and less parabolic at higher energy, have an increased density of states and therefore higher DOS effective mass than a parabolic band. While it is often assumed that also results in a higher thermopower (Seebeck coefficient), calculations of thermopower and Hall carrier concentration from the Kane model show the thermpower is actually reduced. Examples in thermoelectric materials will be discussed.
Projected techno-economic improvements for advanced solar thermal power plants
NASA Technical Reports Server (NTRS)
Fujita, T.; Manvi, R.; Roschke, E. J.
1979-01-01
The projected characteristics of solar thermal power plants (with outputs up to 10 MWe) employing promising advanced technology subsystems/components are compared to current (or pre-1985) steam-Rankine systems. Improvements accruing to advanced technology development options are delineated. The improvements derived from advanced systems result primarily from achieving high efficiencies via solar collector systems which (1) capture a large portion of the available insolation and (2) concentrate this captured solar flux to attain high temperatures required for high heat engine/energy conversion performance. The most efficient solar collector systems employ two-axis tracking. Attractive systems include the central receiver/heliostat and the parabolic dish.
newsletter | contact Share | Solar Lentigo Information for adults A A A This image displays many solar lentigos due to the patient having many sunburns as a child and teenager. Overview A solar lentigo (plural, solar lentigines), also known as a ...
Design of a Thermal Imaging Diagnostic Using 90-Degree, Off-Axis, Parabolic Mirrors
Malone, Robert M.; Becker, Steven A.; Dolan, Daniel H.; Hacking, Richard G.; Hickman, Randy J.; Kaufman, Morris I.; Stevens, Gerald D.; Turley, William D.
2006-09-01
Thermal imaging is an important, though challenging, diagnostic for shockwave experiments. Shock-compressed materials undergo transient temperature changes that cannot be recorded with standard (greater than ms response time) infrared detectors. A further complication arises when optical elements near the experiment are destroyed. We have designed a thermal-imaging system for studying shock temperatures produced inside a gas gun at Sandia National Laboratories. Inexpensive, diamond-turned, parabolic mirrors relay an image of the shocked target to the exterior of the gas gun chamber through a sapphire vacuum port. The 3000–5000-nm portion of this image is directed to an infrared camera which acquires a snapshot of the target with a minimum exposure time of 150 ns. A special mask is inserted at the last intermediate image plane, to provide dynamic thermal background recording during the event. Other wavelength bands of this image are split into high-speed detectors operating at 900–1700 nm, and at 1700–3000 nm for timeresolved pyrometry measurements. This system incorporates 90-degree, off-axis parabolic mirrors, which can collect low f/# light over a broad spectral range, for high-speed imaging. Matched mirror pairs must be used so that aberrations cancel. To eliminate image plane tilt, proper tip-to-tip orientation of the parabolic mirrors is required. If one parabolic mirror is rotated 180 degrees about the optical axis connecting the pair of parabolic mirrors, the resulting image is tilted by 60 degrees. Different focal-length mirrors cannot be used to magnify the image without substantially sacrificing image quality. This paper analyzes performance and aberrations of this imaging diagnostic.
Bates solar industrial process-steam application: preliminary design review
Not Available
1980-01-07
The design is analyzed for a parabolic trough solar process heat system for a cardboard corrugation fabrication facility in Texas. The program is briefly reviewed, including an analysis of the plant and process. The performance modeling for the system is discussed, and the solar system structural design, collector subsystem, heat transport and distribution subsystem are analyzed. The selection of the heat transfer fluid, and ullage and fluid maintenance are discussed, and the master control system and data acquisition system are described. Testing of environmental degradation of materials is briefly discussed. A brief preliminary cost analysis is included. (LEW)
Advanced solar concentrator mass production, operation, and maintenance cost assessment
NASA Technical Reports Server (NTRS)
Niemeyer, W. A.; Bedard, R. J.; Bell, D. M.
1981-01-01
The object of this assessment was to estimate the costs of the preliminary design at: production rates of 100 to 1,000,000 concentrators per year; concentrators per aperture diameters of 5, 10, 11, and 15 meters; and various receiver/power conversion package weights. The design of the cellular glass substrate Advanced Solar Concentrator is presented. The concentrator is an 11 meter diameter, two axis tracking, parabolic dish solar concentrator. The reflective surface of this design consists of inner and outer groups of mirror glass/cellular glass gores.
Criteria for the evaluation of laser solar energy converter systems
NASA Technical Reports Server (NTRS)
Harries, W. L.
1985-01-01
Assuming that a parabolic insolation-collection mirror-based solar pumped laser has a collector and heat emitter whose weights are proportional to their areas, and that the weight of the laser is negligible by comparison, the output power/unit weight can be expressed in terms of the efficiencies and working temperatures of the system. This ratio appears to be several times higher for an IBr laser than for one operating on C3F7I, because the solar utilization efficiency is greater for the former despite its lower working temperature.
Solar Thermal Concept Evaluation
NASA Technical Reports Server (NTRS)
Hawk, Clark W.; Bonometti, Joseph A.
1995-01-01
Concentrated solar thermal energy can be utilized in a variety of high temperature applications for both terrestrial and space environments. In each application, knowledge of the collector and absorber's heat exchange interaction is required. To understand this coupled mechanism, various concentrator types and geometries, as well as, their relationship to the physical absorber mechanics were investigated. To conduct experimental tests various parts of a 5,000 watt, thermal concentrator, facility were made and evaluated. This was in anticipation at a larger NASA facility proposed for construction. Although much of the work centered on solar thermal propulsion for an upper stage (less than one pound thrust range), the information generated and the facility's capabilities are applicable to material processing, power generation and similar uses. The numerical calculations used to design the laboratory mirror and the procedure for evaluating other solar collectors are presented here. The mirror design is based on a hexagonal faceted system, which uses a spherical approximation to the parabolic surface. The work began with a few two dimensional estimates and continued with a full, three dimensional, numerical algorithm written in FORTRAN code. This was compared to a full geometry, ray trace program, BEAM 4, which optimizes the curvatures, based on purely optical considerations. Founded on numerical results, the characteristics of a faceted concentrator were construed. The numerical methodologies themselves were evaluated and categorized. As a result, the three-dimensional FORTRAN code was the method chosen to construct the mirrors, due to its overall accuracy and superior results to the ray trace program. This information is being used to fabricate and subsequently, laser map the actual mirror surfaces. Evaluation of concentrator mirrors, thermal applications and scaling the results of the 10 foot diameter mirror to a much larger concentrator, were studied. Evaluations, recommendations and pit falls regarding the structure, materials and facility design are presented.
NASA Astrophysics Data System (ADS)
Pan, Hongjing; Xing, Ruixiang
2008-03-01
In this paper, we derive blow-up rates for higher-order semilinear parabolic equations and systems. Our proof is by contradiction and uses a scaling argument. This procedure reduces the problems of blow-up rate to Fujita-type theorems. In addition, we also give some new Fujita-type theorems for higher-order semilinear parabolic equations and systems with the time variable on . These results are not restricted to positive solutions.
Automatic Fourier transform and self-Fourier beams due to parabolic potential
NASA Astrophysics Data System (ADS)
Zhang, Yiqi; Liu, Xing; Beli?, Milivoj R.; Zhong, Weiping; Petrovi?, Milan S.; Zhang, Yanpeng
2015-12-01
We investigate the propagation of light beams including Hermite-Gauss, Bessel-Gauss and finite energy Airy beams in a linear medium with parabolic potential. Expectedly, the beams undergo oscillation during propagation, but quite unexpectedly they also perform automatic Fourier transform, that is, periodic change from the beam to its Fourier transform and back. In addition to oscillation, the finite-energy Airy beams exhibit periodic inversion during propagation. The oscillating period of parity-asymmetric beams is twice that of the parity-symmetric beams. Based on the propagation in parabolic potential, we introduce a class of optically-interesting beams that are self-Fourier beams-that is, the beams whose Fourier transforms are the beams themselves.
A parabolic model of drag coefficient for storm surge simulation in the South China Sea
Peng, Shiqiu; Li, Yineng
2015-01-01
Drag coefficient (Cd) is an essential metric in the calculation of momentum exchange over the air-sea interface and thus has large impacts on the simulation or forecast of the upper ocean state associated with sea surface winds such as storm surges. Generally, Cd is a function of wind speed. However, the exact relationship between Cd and wind speed is still in dispute, and the widely-used formula that is a linear function of wind speed in an ocean model could lead to large bias at high wind speed. Here we establish a parabolic model of Cd based on storm surge observations and simulation in the South China Sea (SCS) through a number of tropical cyclone cases. Simulation of storm surges for independent Tropical cyclones (TCs) cases indicates that the new parabolic model of Cd outperforms traditional linear models. PMID:26499262
Time regularity and long-time behavior of parabolic p-Laplace equations on infinite graphs
NASA Astrophysics Data System (ADS)
Hua, Bobo; Mugnolo, Delio
2015-12-01
We consider the so-called discrete p-Laplacian, a nonlinear difference operator that acts on functions defined on the nodes of a possibly infinite graph. We study the corresponding Cauchy problem and identify the generator of the associated nonlinear semigroups. We prove higher order time regularity of the solutions. We investigate the long-time behavior of the solutions and discuss in particular finite extinction time and conservation of mass. Namely, on one hand, for small p if an infinite graph satisfies some isoperimetric inequality, then the solution to the parabolic p-Laplace equation vanishes in finite time; on the other hand, for large p, these parabolic p-Laplace equations always enjoy conservation of mass.
Treatment of ice cover and other thin elastic layers with the parabolic equation method.
Collins, Michael D
2015-03-01
The parabolic equation method is extended to handle problems involving ice cover and other thin elastic layers. Parabolic equation solutions are based on rational approximations that are designed using accuracy constraints to ensure that the propagating modes are handled properly and stability constrains to ensure that the non-propagating modes are annihilated. The non-propagating modes are especially problematic for problems involving thin elastic layers. It is demonstrated that stable results may be obtained for such problems by using rotated rational approximations [Milinazzo, Zala, and Brooke, J. Acoust. Soc. Am. 101, 760-766 (1997)] and generalizations of these approximations. The approach is applied to problems involving ice cover with variable thickness and sediment layers that taper to zero thickness. PMID:25786966
A parabolic model of drag coefficient for storm surge simulation in the South China Sea.
Peng, Shiqiu; Li, Yineng
2015-01-01
Drag coefficient (Cd) is an essential metric in the calculation of momentum exchange over the air-sea interface and thus has large impacts on the simulation or forecast of the upper ocean state associated with sea surface winds such as storm surges. Generally, Cd is a function of wind speed. However, the exact relationship between Cd and wind speed is still in dispute, and the widely-used formula that is a linear function of wind speed in an ocean model could lead to large bias at high wind speed. Here we establish a parabolic model of Cd based on storm surge observations and simulation in the South China Sea (SCS) through a number of tropical cyclone cases. Simulation of storm surges for independent Tropical cyclones (TCs) cases indicates that the new parabolic model of Cd outperforms traditional linear models. PMID:26499262
Reduction of effective terahertz focal spot size by means of nested concentric parabolic reflectors
NASA Astrophysics Data System (ADS)
Neumann, V. A.; Laurita, N. J.; Pan, LiDong; Armitage, N. P.
2015-09-01
An ongoing limitation of terahertz spectroscopy is that the technique is generally limited to the study of relatively large samples of order 4 mm across due to the generally large size of the focal beam spot. We present a nested concentric parabolic reflector design which can reduce the terahertz focal spot size. This parabolic reflector design takes advantage of the feature that reflected rays experience a relative time delay which is the same for all paths. The increase in effective optical path for reflected light is equivalent to the aperture diameter itself. We have shown that the light throughput of an aperture of 2 mm can be increased by a factor 15 as compared to a regular aperture of the same size at low frequencies. This technique can potentially be used to reduce the focal spot size in terahertz spectroscopy and enable the study of smaller samples.
A parabolic model of drag coefficient for storm surge simulation in the South China Sea
NASA Astrophysics Data System (ADS)
Peng, Shiqiu; Li, Yineng
2015-10-01
Drag coefficient (Cd) is an essential metric in the calculation of momentum exchange over the air-sea interface and thus has large impacts on the simulation or forecast of the upper ocean state associated with sea surface winds such as storm surges. Generally, Cd is a function of wind speed. However, the exact relationship between Cd and wind speed is still in dispute, and the widely-used formula that is a linear function of wind speed in an ocean model could lead to large bias at high wind speed. Here we establish a parabolic model of Cd based on storm surge observations and simulation in the South China Sea (SCS) through a number of tropical cyclone cases. Simulation of storm surges for independent Tropical cyclones (TCs) cases indicates that the new parabolic model of Cd outperforms traditional linear models.
Role of secondary instability theory and parabolized stability equations in transition modeling
NASA Technical Reports Server (NTRS)
El-Hady, Nabil M.; Dinavahi, Surya P.; Chang, Chau-Lyan; Zang, Thomas A.
1993-01-01
In modeling the laminar-turbulent transition region, the designer depends largely on benchmark data from experiments and/or direct numerical simulations that are usually extremely expensive. An understanding of the evolution of the Reynolds stresses, turbulent kinetic energy, and quantifies in the transport equations like the dissipation and production is essential in the modeling process. The secondary instability theory and the parabolized stability equations method are used to calculate these quantities, which are then compared with corresponding quantities calculated from available direct numerical simulation data for the incompressible boundary-layer flow of laminar-turbulent transition conditions. The potential of the secondary instability theory and the parabolized stability equations approach in predicting these quantities is discussed; results indicate that inexpensive data that are useful for transition modeling in the early stages of the transition region can be provided by these tools.
Galerkin/Runge-Kutta discretizations for parabolic equations with time dependent coefficients
NASA Technical Reports Server (NTRS)
Keeling, Stephen L.
1987-01-01
A new class of fully discrete Galerkin/Runge-Kutta methods is constructed and analyzed for linear parabolic initial boundary value problems with time dependent coefficients. Unlike any classical counterpart, this class offers arbitrarily high order convergence while significantly avoiding what has been called order reduction. In support of this claim, error estimates are proved, and computational results are presented. Additionally, since the time stepping equations involve coefficient matrices changing at each time step, a preconditioned iterative technique is used to solve the linear systems only approximately. Nevertheless, the resulting algorithm is shown to preserve the original convergence rate while using only the order of work required by the base scheme applied to a linear parabolic problem with time independent coefficients. Furthermore, it is noted that special Runge-Kutta methods allow computations to be performed in parallel so that the final execution time can be reduced to that of a low order method.
Near-InfraRed for Changes in Brain Activity During Parabolic Flights?
NASA Astrophysics Data System (ADS)
Abeln, V.; Schneider, S.
2013-02-01
The purpose of this study was to investigate whether previously found decreases of prefrontal electrocortical activity in weightlessness during parabolic flights are due to hemodynamic or altered central-nervous activity within the brain. Two near-infrared spectroscopy (NIRS) probes placed on the prefrontal cortex were used to record changes of oxygenated- (O2Hb) and deoxygenated (HHb) hemoglobin concentration during ten parabolas of nine un-medicated subjects taking part in a parabolic flight. Compared to normal gravity, O2Hb decreased with the onset of hypergravity1 and considerably increased during microgravity, whereas no difference for hypergravity2 was found. HHb showed no significant change during hypergravity1 , but a decrease during hypergravity2 and a slight increase in microgravity. Based on the finding of this study, previously found changes in electrocortical activity cannot only depend on a redistribution of blood volume.
Reduction of Effective Terahertz Focal Spot Size By Means Of Nested Concentric Parabolic Reflectors
Neumann, V A; Pan, LiDong; Armitage, N P
2015-01-01
An ongoing limitation of terahertz spectroscopy is that the technique is generally limited to the study of relatively large samples of order 4 mm across due to the generally large size of the focal beam spot. We present a nested concentric parabolic reflector design which can reduce the terahertz focal spot size. This parabolic reflector design takes advantage of the feature that reflected rays experience a relative time delay which is the same for all paths. The increase in effective optical path for reflected light is equivalent to the aperture diameter itself. We have shown that the light throughput of an aperture of 2 mm can be increased by a factor 15 as compared to a regular aperture of the same size at low frequencies. This technique can potentially be used to reduce the focal spot size in terahertz spectroscopy and enable the study of smaller samples.
Evaluation of the three-dimensional parabolic flow computer program SHIP
NASA Technical Reports Server (NTRS)
Pan, Y. S.
1978-01-01
The three-dimensional parabolic flow program SHIP designed for predicting supersonic combustor flow fields is evaluated to determine its capabilities. The mathematical foundation and numerical procedure are reviewed; simplifications are pointed out and commented upon. The program is then evaluated numerically by applying it to several subsonic and supersonic, turbulent, reacting and nonreacting flow problems. Computational results are compared with available experimental or other analytical data. Good agreements are obtained when the simplifications on which the program is based are justified. Limitations of the program and the needs for improvement and extension are pointed out. The present three dimensional parabolic flow program appears to be potentially useful for the development of supersonic combustors.
NASA Technical Reports Server (NTRS)
Robertson, J. S.; Siegman, W. L.; Jacobson, M. J.
1989-01-01
There is substantial interest in the analytical and numerical modeling of low-frequency, long-range atmospheric acoustic propagation. Ray-based models, because of frequency limitations, do not always give an adequate prediction of quantities such as sound pressure or intensity levels. However, the parabolic approximation method, widely used in ocean acoustics, and often more accurate than ray models for lower frequencies of interest, can be applied to acoustic propagation in the atmosphere. Modifications of an existing implicit finite-difference implementation for computing solutions to the parabolic approximation are discussed. A locally-reacting boundary is used together with a one-parameter impedance model. Intensity calculations are performed for a number of flow resistivity values in both quiescent and windy atmospheres. Variations in the value of this parameter are shown to have substantial effects on the spatial variation of the acoustic signal.
Galerkin/Runge-Kutta discretizations for parabolic equations with time-dependent coefficients
NASA Technical Reports Server (NTRS)
Keeling, Stephen L.
1989-01-01
A new class of fully discrete Galerkin/Runge-Kutta methods is constructed and analyzed for linear parabolic initial boundary value problems with time dependent coefficients. Unlike any classical counterpart, this class offers arbitrarily high order convergence while significantly avoiding what has been called order reduction. In support of this claim, error estimates are proved, and computational results are presented. Additionally, since the time stepping equations involve coefficient matrices changing at each time step, a preconditioned iterative technique is used to solve the linear systems only approximately. Nevertheless, the resulting algorithm is shown to preserve the original convergence rate while using only the order of work required by the base scheme applied to a linear parabolic problem with time independent coefficients. Furthermore, it is noted that special Runge-Kutta methods allow computations to be performed in parallel so that the final execution time can be reduced to that of a low order method.
Parabolic single-crystal diamond lenses for coherent x-ray imaging
NASA Astrophysics Data System (ADS)
Terentyev, Sergey; Blank, Vladimir; Polyakov, Sergey; Zholudev, Sergey; Snigirev, Anatoly; Polikarpov, Maxim; Kolodziej, Tomasz; Qian, Jun; Zhou, Hua; Shvyd'ko, Yuri
2015-09-01
We demonstrate parabolic single-crystal diamond compound refractive lenses designed for coherent x-ray imaging resilient to extreme thermal and radiation loading expected from next generation light sources. To ensure the preservation of coherence and resilience, the lenses are manufactured from the highest-quality single-crystalline synthetic diamond material grown by a high-pressure high-temperature technique. Picosecond laser milling is applied to machine lenses to parabolic shapes with a ? 1 ? m precision and surface roughness. A compound refractive lens comprised of six lenses with a radius of curvature R = 200 ? m at the vertex of the parabola and a geometrical aperture A = 900 ? m focuses 10 keV x-ray photons from an undulator source at the Advanced Photon Source facility to a focal spot size of ? 20 × 90 ? m 2 with a gain factor of ? 50 - 100 .
Blair, N.; Mehos, M.; Christensen, C.; Cameron, C.
2008-05-01
A comprehensive solar technology systems analysis model, the Solar Advisor Model (SAM), has been developed to support the federal R&D community and the solar industry by staff at the National Renewable Energy Laboratory (NREL) and Sandia National Laboratory. This model is able to model the finances, incentives, and performance of flat-plate photovoltaic (PV), concentrating PV, and concentrating solar power (specifically, parabolic troughs). The primary function of the model is to allow users to investigate the impact of variations in performance, cost, and financial parameters to better understand their impact on key figures of merit. Figures of merit related to the cost and performance of these systems include, but aren't limited to, system output, system efficiencies, levelized cost of energy, return on investment, and system capital and O&M costs. There are several models within SAM to model the performance of photovoltaic modules and inverters. This paper presents an overview of each PV and inverter model, introduces a new generic model, and briefly discusses the concentrating solar power (CSP) parabolic trough model. A comparison of results using the different PV and inverter models is also presented.
Quantum damped oscillator II: Bateman's Hamiltonian vs. 2D parabolic potential barrier
Chruscinski, Dariusz . E-mail: darch@phys.uni.torun.pl
2006-04-15
We show that quantum Bateman's system which arises in the quantization of a damped harmonic oscillator is equivalent to a quantum problem with 2D parabolic potential barrier known also as 2D inverted isotropic oscillator. It turns out that this system displays the family of complex eigenvalues corresponding to the poles of analytical continuation of the resolvent operator to the complex energy plane. It is shown that this representation is more suitable than the hyperbolic one used recently by Blasone and Jizba.
Free vibration behavior of laminated composite stiffened elliptic parabolic shell panel with cutout
NASA Astrophysics Data System (ADS)
Sahoo, Sarmila
2015-01-01
In this paper free vibration behavior of laminated composite stiffened elliptic parabolic shell has been analyzed in terms of natural frequency and mode shape. Finite element method has been applied using an eight-noded curved quadratic isoparametric element for shell with a three noded curved beam element for stiffener. Cross and angle ply shells with different edge conditions have been studied varying the size and position of the cutouts to arrive at a set of inferences of practical engineering significances.
On the rate of convergence of parabolic semigroups of holomorphic functions
NASA Astrophysics Data System (ADS)
Betsakos, Dimitrios
2015-06-01
Let be a semigroup of holomorphic self-maps of the unit disk with Denjoy-Wolff point 1 and associated planar domain . We further assume that for all , (angular derivative), namely the semigroup is parabolic. We study the rate of convergence of the semigroup to 1. We prove then that for every , there exists a positive constant such that . If, in addition, is contained in a half-plane, then we prove a stronger estimate:.
Alkhutov, Yu A; Zhikov, V V
2014-03-31
The paper is concerned with the solvability of the initial-boundary value problem for second-order parabolic equations with variable nonlinearity exponents. In the model case, this equation contains the p-Laplacian with a variable exponent p(x,t). The problem is shown to be uniquely solvable, provided the exponent p is bounded away from both 1 and ? and is log-Hölder continuous, and its solution satisfies the energy equality. Bibliography: 18 titles.
The Definition and Measurement of the Topological Entropy per Unit Volume in Parabolic PDE's
P. Collet; J. -P. Eckmann
1998-05-20
We define the topological entropy per unit volume in parabolic PDE's such as the complex Ginzburg-Landau equation, and show that it exists, and is bounded by the upper Hausdorff dimension times the maximal expansion rate. We then give a constructive implementation of a bound on the inertial range of such equations. Using this bound, we are able to propose a finite sampling algorithm which allows (in principle) to measure this entropy from experimental data.
Laser-written parabolic micro-antennas for efficient photon collection
Schell, Andreas W. Neumer, Tanja; Benson, Oliver; Shi, Qiang; Kaschke, Johannes; Fischer, Joachim; Wegener, Martin
2014-12-08
Efficient collection of photons from solid-state single-photon emitters, like quantum dots, molecules, or defect centers in diamond, is a very demanding task. Here, we introduce parabolic micro-antennas fabricated by two-photon direct laser-writing to enhance the collection efficiency by directing emitted light into a small solid angle. The antennas can be fabricated on-site at the position of a pre-selected single-photon emitter.
Mahillo-Isla, R; Gon?alez-Morales, M J; Dehesa-Martínez, C
2011-06-01
The slowly varying envelope approximation is applied to the radiation problems of the Helmholtz equation with a planar single-layer and dipolar sources. The analyses of such problems provide procedures to recover solutions of the Helmholtz equation based on the evaluation of solutions of the parabolic wave equation at a given plane. Furthermore, the conditions that must be fulfilled to apply each procedure are also discussed. The relations to previous work are given as well. PMID:21643384
Life science experiments during parabolic flight: The McGill experience
NASA Technical Reports Server (NTRS)
Watt, D. G. D.
1988-01-01
Over the past twelve years, members of the Aerospace Medical Research Unit of McGill University have carried out a wide variety of tests and experiments in the weightless condition created by parabolic flight. This paper discusses the pros and cons of that environment for the life scientist, and uses examples from the McGill program of the types of activities which can be carried out in a transport aircraft such as the NASA KC-135.
NASA Astrophysics Data System (ADS)
Mei, Ming; Peng, Hongyun; Wang, Zhi-An
2015-11-01
This paper concerns a parabolic-hyperbolic system on the half space R+ with boundary effect. The system is derived from a singular chemotaxis model describing the initiation of tumor angiogenesis. We show that the solution of the system subject to appropriate boundary conditions converges to a traveling wave profile as time tends to infinity if the initial data is a small perturbation around the wave which is shifted far away from the boundary but its amplitude can be arbitrarily large.
Low-Cost, Light Weight, Thin Film Solar Concentrator
NASA Technical Reports Server (NTRS)
Ganapathi, G.; Palisoc, A.; Nesmith, B.; Greschik, G.; Gidanian, K.; Kindler, A.
2013-01-01
This research addresses a cost barrier towards achieving a solar thermal collector system with an installed cost of $75/sq m and meet the Department of Energy's (DOE's) performance targets for optical errors, operations during windy conditions and lifetime. Current concentrators can cost as much as 40-50% of the total installed costs for a CSP plant. In order to reduce the costs from current $200-$250/sq m, it is important to focus on the overall system. The reflector surface is a key cost driver, and our film-based polymer reflector will help significantly in achieving DOE's cost target of $75/sq m. The ease of manufacturability, installation and replacement make this technology a compelling one to develop. This technology can be easily modified for a variety of CSP options including heliostats, parabolic dishes and parabolic troughs.
Storage in residential solar total-energy systems
NASA Astrophysics Data System (ADS)
Leigh, R. W.
1980-12-01
The potential role of energy storage devices in solar total energy systems operating in a stand alone mode is examined. High temperature thermal storage is examined in the context of systems employing parabolic trough collectors and Rankine cycle conversion while batteries are evaluated in systems based on parabolic dish concentrators with Stirling cycle conversion or on nonconcentrating photovoltaic systems. In all three systems, storage was found to be advantageous in cases involving high future fuel prices and collectors meeting current cost goals, while storage was not found to be viable at fuel prices remaining near current levels and collector costs exceeding current expectations by substantial margins. Factors making storage more or less desirable are discussed. Throughout, analyses based on minimum cost (optimal) systems are employed.
Blair, N.; Mehos, M.; Christensen, C.; Cameron, C.
2008-01-01
A comprehensive solar technology systems analysis model, the Solar Advisor Model (SAM), has been developed to support the federal R&D community and the solar industry by staff at the National Renewable Energy Laboratory (NREL) and Sandia National Laboratory. This model is able to model the finances, incentives, and performance of flat-plate photovoltaic (PV), concentrating PV, and concentrating solar power (specifically, parabolic troughs). The primary function of the model is to allow users to investigate the impact of variations in performance, cost, and financial parameters to better understand their impact on key figures of merit. Figures of merit related to the cost and performance of these systems include, but aren't limited to, system output, system efficiencies, levelized cost of energy, return on investment, and system capital and O&M costs. SAM allows users to do complex system modeling with an intuitive graphical user interface (GUI). In fact, all tables and graphics for this paper are taken directly from the model GUI. This model has the capability to compare different solar technologies within the same interface, making use of similar cost and finance assumptions. Additionally, the ability to do parametric and sensitivity analysis is central to this model. There are several models within SAM to model the performance of photovoltaic modules and inverters. This paper presents an overview of each PV and inverter model, introduces a new generic model, and briefly discusses the concentrating solar power (CSP) parabolic trough model. A comparison of results using the different PV and inverter models is also presented.
Aerial projection of three-dimensional motion pictures by electro-holography and parabolic mirrors
Kakue, Takashi; Nishitsuji, Takashi; Kawashima, Tetsuya; Suzuki, Keisuke; Shimobaba, Tomoyoshi; Ito, Tomoyoshi
2015-01-01
We demonstrate an aerial projection system for reconstructing 3D motion pictures based on holography. The system consists of an optical source, a spatial light modulator corresponding to a display and two parabolic mirrors. The spatial light modulator displays holograms calculated by computer and can reconstruct holographic motion pictures near the surface of the modulator. The two parabolic mirrors can project floating 3D images of the motion pictures formed by the spatial light modulator without mechanical scanning or rotating. In this demonstration, we used a phase-modulation-type spatial light modulator. The number of pixels and the pixel pitch of the modulator were 1,080?×?1,920 and 8.0??m?×?8.0??m, respectively. The diameter, the height and the focal length of each parabolic mirror were 288?mm, 55?mm and 100?mm, respectively. We succeeded in aerially projecting 3D motion pictures of size ~2.5?mm3 by this system constructed by the modulator and mirrors. In addition, by applying a fast computational algorithm for holograms, we achieved hologram calculations at ~12?ms per hologram with 4 CPU cores. PMID:26152453
Aerial projection of three-dimensional motion pictures by electro-holography and parabolic mirrors
NASA Astrophysics Data System (ADS)
Kakue, Takashi; Nishitsuji, Takashi; Kawashima, Tetsuya; Suzuki, Keisuke; Shimobaba, Tomoyoshi; Ito, Tomoyoshi
2015-07-01
We demonstrate an aerial projection system for reconstructing 3D motion pictures based on holography. The system consists of an optical source, a spatial light modulator corresponding to a display and two parabolic mirrors. The spatial light modulator displays holograms calculated by computer and can reconstruct holographic motion pictures near the surface of the modulator. The two parabolic mirrors can project floating 3D images of the motion pictures formed by the spatial light modulator without mechanical scanning or rotating. In this demonstration, we used a phase-modulation-type spatial light modulator. The number of pixels and the pixel pitch of the modulator were 1,080?×?1,920 and 8.0??m?×?8.0??m, respectively. The diameter, the height and the focal length of each parabolic mirror were 288?mm, 55?mm and 100?mm, respectively. We succeeded in aerially projecting 3D motion pictures of size ~2.5?mm3 by this system constructed by the modulator and mirrors. In addition, by applying a fast computational algorithm for holograms, we achieved hologram calculations at ~12?ms per hologram with 4 CPU cores.
Aerial projection of three-dimensional motion pictures by electro-holography and parabolic mirrors.
Kakue, Takashi; Nishitsuji, Takashi; Kawashima, Tetsuya; Suzuki, Keisuke; Shimobaba, Tomoyoshi; Ito, Tomoyoshi
2015-01-01
We demonstrate an aerial projection system for reconstructing 3D motion pictures based on holography. The system consists of an optical source, a spatial light modulator corresponding to a display and two parabolic mirrors. The spatial light modulator displays holograms calculated by computer and can reconstruct holographic motion pictures near the surface of the modulator. The two parabolic mirrors can project floating 3D images of the motion pictures formed by the spatial light modulator without mechanical scanning or rotating. In this demonstration, we used a phase-modulation-type spatial light modulator. The number of pixels and the pixel pitch of the modulator were 1,080 × 1,920 and 8.0 ?m × 8.0 ?m, respectively. The diameter, the height and the focal length of each parabolic mirror were 288 mm, 55 mm and 100 mm, respectively. We succeeded in aerially projecting 3D motion pictures of size ~2.5 mm(3) by this system constructed by the modulator and mirrors. In addition, by applying a fast computational algorithm for holograms, we achieved hologram calculations at ~12 ms per hologram with 4 CPU cores. PMID:26152453
The Effect of Boundary Support and Reflector Dimensions on Inflatable Parabolic Antenna Performance
NASA Technical Reports Server (NTRS)
Coleman, Michael J.; Baginski, Frank; Romanofsky, Robert R.
2011-01-01
For parabolic antennas with sufficient surface accuracy, more power can be radiated with a larger aperture size. This paper explores the performance of antennas of various size and reflector depth. The particular focus is on a large inflatable elastic antenna reflector that is supported about its perimeter by a set of elastic tendons and is subjected to a constant hydrostatic pressure. The surface accuracy of the antenna is measured by an RMS calculation, while the reflector phase error component of the efficiency is determined by computing the power density at boresight. In the analysis, the calculation of antenna efficiency is not based on the Ruze Equation. Hence, no assumption regarding the distribution of the reflector surface distortions is presumed. The reflector surface is modeled as an isotropic elastic membrane using a linear stress-strain constitutive relation. Three types of antenna reflector construction are considered: one molded to an ideal parabolic form and two different flat panel design patterns. The flat panel surfaces are constructed by seaming together panels in a manner that the desired parabolic shape is approximately attained after pressurization. Numerical solutions of the model problem are calculated under a variety of conditions in order to estimate the accuracy and efficiency of these antenna systems. In the case of the flat panel constructions, several different cutting patterns are analyzed in order to determine an optimal cutting strategy.
Heath, G.; Burkhardt, J.; Turchi, C.; Decker, T.; Kutscher, C.
2009-07-20
In the United States, concentrating solar power (CSP) is one of the most promising renewable energy (RE) technologies for reduction of electric sector greenhouse gas (GHG) emissions and for rapid capacity expansion. It is also one of the most price-competitive RE technologies, thanks in large measure to decades of field experience and consistent improvements in design. One of the key design features that makes CSP more attractive than many other RE technologies, like solar photovoltaics and wind, is the potential for including relatively low-cost and efficient thermal energy storage (TES), which can smooth the daily fluctuation of electricity production and extend its duration into the evening peak hours or longer. Because operational environmental burdens are typically small for RE technologies, life cycle assessment (LCA) is recognized as the most appropriate analytical approach for determining their environmental impacts of these technologies, including CSP. An LCA accounts for impacts from all stages in the development, operation, and decommissioning of a CSP plant, including such upstream stages as the extraction of raw materials used in system components, manufacturing of those components, and construction of the plant. The National Renewable Energy Laboratory (NREL) is undertaking an LCA of modern CSP plants, starting with those of parabolic trough design.
The sun-tracking control of solar collectors using high-performance step motors
NASA Technical Reports Server (NTRS)
Hughes, R. O.
1977-01-01
Sun-tracking solar energy-focusing devices involving a central receiver, thermionic conversion, or a distributed solar thermal collector system are described. The Perkins solar collector uses a fixed focal point about which an 18 m-diameter parabolic dish moves on tracks. The elevation axis also moves on a circular track. A microprocessor manipulates sun sensor information and sun ephemeris data to ensure correct placement. Stepper motors are digital devices which provide direct interface with digital electronics and a wide dynamic range, and could easily be associated with the microprocessors. Design philosophy, performance criteria, wind load analysis, and control system requirements are also discussed.
Solar Radius Variations: An Inquisitive Wavelength Dependence
NASA Astrophysics Data System (ADS)
Rozelot, Jean Pierre; Kosovichev, Alexander; Kilcik, Ali
2015-10-01
Recent solar radius determinations from space observations of Mercury and Venus transits have been made by different teams in 2003, 2006, 2012, and 2014. Seemingly the results are not consistent: the authors interpreted the discrepancies as caused by the different methods of analysis. However, looking at the wavelength dependence and adding other available observations from X-EUV up to radio, a typical wavelength dependence can be found, reflecting the different heights at which the lines are formed. Measurements obtained during different periods of time would, in principle, allow us to detect a signature of radius temporal dependence. However, the available data are not sufficiently numerous to detect a significant dependence, at least at the level of the uncertainty at which the observations were made. Lastly, no unique theoretical model is available today to reproduce the strong wavelength dependence of the solar radius, which shows an unexpected minimum at around (6.6 ± 1.9) ?m, after a parabolic fit.
Detailed Physical Trough Model for NREL's Solar Advisor Model: Preprint
Wagner, M. J.; Blair, N.; Dobos, A.
2010-10-01
Solar Advisor Model (SAM) is a free software package made available by the National Renewable Energy Laboratory (NREL), Sandia National Laboratory, and the US Department of Energy. SAM contains hourly system performance and economic models for concentrating solar power (CSP) systems, photovoltaic, solar hot-water, and generic fuel-use technologies. Versions of SAM prior to 2010 included only the parabolic trough model based on Excelergy. This model uses top-level empirical performance curves to characterize plant behavior, and thus is limited in predictive capability for new technologies or component configurations. To address this and other functionality challenges, a new trough model; derived from physical first principles was commissioned to supplement the Excelergy-based empirical model. This new 'physical model' approaches the task of characterizing the performance of the whole parabolic trough plant by replacing empirical curve-fit relationships with more detailed calculations where practical. The resulting model matches the annual performance of the SAM empirical model (which has been previously verified with plant data) while maintaining run-times compatible with parametric analysis, adding additional flexibility in modeled system configurations, and providing more detailed performance calculations in the solar field, power block, piping, and storage subsystems.
ERIC Educational Resources Information Center
Eaton, William W.
Presented is the utilization of solar radiation as an energy resource principally for the production of electricity. Included are discussions of solar thermal conversion, photovoltic conversion, wind energy, and energy from ocean temperature differences. Future solar energy plans, the role of solar energy in plant and fossil fuel production, and…
NASA Technical Reports Server (NTRS)
1979-01-01
The solar collectors shown are elements of domestic solar hot water systems produced by Solar One Ltd., Virginia Beach, Virginia. Design of these systems benefited from technical expertise provided Solar One by NASA's Langley Research Center. The company obtained a NASA technical support package describing the d e sign and operation of solar heating equipment in NASA's Tech House, a demonstration project in which aerospace and commercial building technology are combined in an energy- efficient home. Solar One received further assistance through personal contact with Langley solar experts. The company reports that the technical information provided by NASA influenced Solar One's panel design, its selection of a long-life panel coating which increases solar collection efficiency, and the method adopted for protecting solar collectors from freezing conditions.
Research and development on a distributed type solar thermal power generation plant
NASA Astrophysics Data System (ADS)
Sumida, I.; Tsukamoto, M.; Sakamoto, T.; Taki, T.; Sato, S.
1983-12-01
The R&D on a solar thermal power generation system of the plane parabolic type within the framework of the Japanese Sunshine Project is described. This system realizes high concentration of solar energy with a special concentrator module which combines 100 flat plate mirror heliostats of the central tower system with 5 parabolic troughs of the distributed system. A molten salt (KCl-LiCl) type thermal storage unit is used to superheat saturated steam supplied by accumulators to 300-350 C for 90 minutes after 5 hours of heat storage. Specifications and hydrodynamic characteristics for a 1000 kWe pilot plant in Nio, Kagawa, Japan, constructed in 1980 are given.
NASA Astrophysics Data System (ADS)
Yan, Na; Baas, Andreas C. W.
2015-01-01
The formation and evolution of parabolic aeolian dunes depend on vegetation, and as such are particularly sensitive to changes in environmental controls (e.g., temperature, precipitation, and wind regime) as well as to human disturbances (e.g., grazing, agriculture, and recreation). Parabolic dunes can develop from the stabilisation of highly mobile barchan dunes and transverse dunes as well as from blowouts, as a consequence of colonisation and establishment of vegetation when aeolian sand transport is reduced and/or when water stress is relieved (by increasing precipitation, for instance). Conversely, existing parabolic dunes can be activated and may be transformed into barchan dunes and/or transverse dunes when vegetation suffers environmental or anthropogenic stresses. Predicted increases in temperature and drought severity in various regions raise concerns that dune activation and transformations may intensify, and this intensification would have far-reaching implications for environmental, social, and economic sustainability. To date, a broad examination of the development of parabolic dunes and their related transformations across a variety of climate gradients has been absent. This paper reviews existing literature, compares data on the morphology and development of parabolic dunes in a comprehensive global inventory, and scrutinises the mechanisms of different dune transformations and the eco-geomorphic interactions involved. This knowledge is then integrated into a conceptual framework to facilitate understanding and prediction of potential aeolian dune transformations induced by changes in environmental controls and human activities. This conceptual framework can aid judicious land management policies for better adaptations to climatic changes.
Scattering Solar Thermal Concentrators
Giebink, Noel C.
2015-01-31
This program set out to explore a scattering-based approach to concentrate sunlight with the aim of improving collector field reliability and of eliminating wind loading and gross mechanical movement through the use of a stationary collection optic. The approach is based on scattering sunlight from the focal point of a fixed collection optic into the confined modes of a sliding planar waveguide, where it is transported to stationary tubular heat transfer elements located at the edges. Optical design for the first stage of solar concentration, which entails focusing sunlight within a plane over a wide range of incidence angles (>120 degree full field of view) at fixed tilt, led to the development of a new, folded-path collection optic that dramatically out-performs the current state-of-the-art in scattering concentration. Rigorous optical simulation and experimental testing of this collection optic have validated its performance. In the course of this work, we also identified an opportunity for concentrating photovoltaics involving the use of high efficiency microcells made in collaboration with partners at the University of Illinois. This opportunity exploited the same collection optic design as used for the scattering solar thermal concentrator and was therefore pursued in parallel. This system was experimentally demonstrated to achieve >200x optical concentration with >70% optical efficiency over a full day by tracking with <1 cm of lateral movement at fixed latitude tilt. The entire scattering concentrator waveguide optical system has been simulated, tested, and assembled at small scale to verify ray tracing models. These models were subsequently used to predict the full system optical performance at larger, deployment scale ranging up to >1 meter aperture width. Simulations at an aperture widths less than approximately 0.5 m with geometric gains ~100x predict an overall optical efficiency in the range 60-70% for angles up to 50 degrees from normal. However, the concentrator optical efficiency was found to decrease significantly with increasing aperture width beyond 0.5 m due to parasitic waveguide out-coupling loss and low-level absorption that become dominant at larger scale. A heat transfer model was subsequently implemented to predict collector fluid heat gain and outlet temperature as a function of flow rate using the optical model as a flux input. It was found that the aperture width size limitation imposed by the optical efficiency characteristics of the waveguide limits the absolute optical power delivered to the heat transfer element per unit length. As compared to state-of-the-art parabolic trough CPV system aperture widths approaching 5 m, this limitation leads to an approximate factor of order of magnitude increase in heat transfer tube length to achieve the same heat transfer fluid outlet temperature. The conclusion of this work is that scattering solar thermal concentration cannot be implemented at the scale and efficiency required to compete with the performance of current parabolic trough CSP systems. Applied within the alternate context of CPV, however, the results of this work have likely opened up a transformative new path that enables quasi-static, high efficiency CPV to be implemented on rooftops in the form factor of traditional fixed-panel photovoltaics.
Performance testing of the Acurex solar-collector Model 3001-03
Dudley, V.E.; Workhoven, R.M.
1982-03-01
Results are summarized of tests conducted at the Collector Module Test Facility on an Acurex Model 3001-03 Parabolic Trough Concentrating Solar Collector. Test temperaure range was 100/sup 0/C to 300/sup 0/C. Tests were conducted with the collector axis oriented east-west and again with the collector axis oriented north-south. Three collectors were tested: one using polished aluminum mirrors, one using glass mirrors, and another using an aluminized acrylic film mirror.
Aubry-Hivet, D; Nziengui, H; Rapp, K; Oliveira, O; Paponov, I A; Li, Y; Hauslage, J; Vagt, N; Braun, M; Ditengou, F A; Dovzhenko, A; Palme, K
2014-01-01
Plant roots are among most intensively studied biological systems in gravity research. Altered gravity induces asymmetric cell growth leading to root bending. Differential distribution of the phytohormone auxin underlies root responses to gravity, being coordinated by auxin efflux transporters from the PIN family. The objective of this study was to compare early transcriptomic changes in roots of Arabidopsis thaliana wild type, and pin2 and pin3 mutants under parabolic flight conditions and to correlate these changes to auxin distribution. Parabolic flights allow comparison of transient 1-g, hypergravity and microgravity effects in living organisms in parallel. We found common and mutation-related genes differentially expressed in response to transient microgravity phases. Gene ontology analysis of common genes revealed lipid metabolism, response to stress factors and light categories as primarily involved in response to transient microgravity phases, suggesting that fundamental reorganisation of metabolic pathways functions upstream of a further signal mediating hormonal network. Gene expression changes in roots lacking the columella-located PIN3 were stronger than in those deprived of the epidermis and cortex cell-specific PIN2. Moreover, repetitive exposure to microgravity/hypergravity and gravity/hypergravity flight phases induced an up-regulation of auxin responsive genes in wild type and pin2 roots, but not in pin3 roots, suggesting a critical function of PIN3 in mediating auxin fluxes in response to transient microgravity phases. Our study provides important insights towards understanding signal transduction processes in transient microgravity conditions by combining for the first time the parabolic flight platform with the transcriptome analysis of different genetic mutants in the model plant, Arabidopsis. PMID:24373012
Nearly Interactive Parabolized Navier-Stokes Solver for High Speed Forebody and Inlet Flows
NASA Technical Reports Server (NTRS)
Benson, Thomas J.; Liou, May-Fun; Jones, William H.; Trefny, Charles J.
2009-01-01
A system of computer programs is being developed for the preliminary design of high speed inlets and forebodies. The system comprises four functions: geometry definition, flow grid generation, flow solver, and graphics post-processor. The system runs on a dedicated personal computer using the Windows operating system and is controlled by graphical user interfaces written in MATLAB (The Mathworks, Inc.). The flow solver uses the Parabolized Navier-Stokes equations to compute millions of mesh points in several minutes. Sample two-dimensional and three-dimensional calculations are demonstrated in the paper.
Operation and performance of the Ciba-Corning 512 coagulation monitor during parabolic flight
NASA Technical Reports Server (NTRS)
Gocke, Robyn; Lloyd, Charles W.; Greenthaner, Nancy K.
1991-01-01
The goal was to assess the functionality and evaluate the procedures and operations required to operate the Ciba-Corning 512 Coagulation Monitor during parabolic flight. This monitor determines the clotting characteristics of blood. The analyzer operates by laser detection of the cessation of blood flow in a capillary channel within a test cartridge. Test simulator results were excellent for both pre-and post-flight. In-flight results were not obtained due to the warm-up time required for the simulator. Since this is an electronic function only, the expected results on the simulator would be the same in zero-g.
Stabilization of the solution of a doubly nonlinear parabolic equation
Andriyanova, Č R; Mukminov, F Kh
2013-09-30
The method of Galerkin approximations is employed to prove the existence of a strong global (in time) solution of a doubly nonlinear parabolic equation in an unbounded domain. The second integral identity is established for Galerkin approximations, and passing to the limit in it an estimate for the decay rate of the norm of the solution from below is obtained. The estimates characterizing the decay rate of the solution as x?? obtained here are used to derive an upper bound for the decay rate of the solution with respect to time; the resulting estimate is pretty close to the lower one. Bibliography: 17 titles.
Visualization of Shock Wave Driven by Millimeter Wave Plasma in a Parabolic Thruster
Yamaguchi, Toshikazu; Shimada, Yutaka; Shiraishi, Yuya; Shibata, Teppei; Komurasaki, Kimiya; Oda, Yasuhisa; Kajiwara, Ken; Takahashi, Koji; Kasugai, Atsushi; Sakamoto, Keishi; Arakawa, Yoshihiro
2010-05-06
By focusing a high-power millimeter wave beam generated by a 170 GHz gyrotron, a breakdown occurred and a shock wave was driven by plasma heated by following microwave energy. The shock wave and the plasma around a focal point of a parabolic thruster were visualized by a shadowgraph method, and a transition of structures between the shock wave and the plasma was observed. There was a threshold local power density to make the transition, and the propagation velocity at the transition was around 800 m/s.
Blow-up properties for a degenerate parabolic system with nonlinear localized sources
NASA Astrophysics Data System (ADS)
Wang, Minxing; Wei, Yunfeng
2008-07-01
This paper deals with blow-up properties for a degenerate parabolic system with nonlinear localized sources subject to the homogeneous Dirichlet boundary conditions. The main aim of this paper is to study the blow-up rate estimate and the uniform blow-up profile of the blow-up solution. Our conclusions extend the results of [L.L. Du, Blow-up for a degenerate reaction-diffusion system with nonlinear localized sources, J. Math. Anal. Appl. 324 (2006) 304-320]. At the end, the blow-up set and blow up rate with respect to the radial variable is considered when the domain [Omega] is a ball.
NASA Astrophysics Data System (ADS)
Rezaiee, S. H.; Askari, H. R.; Rahimi, M.; Fatemidokht, A.
2013-07-01
In this paper, we have investigated the electron Raman scattering in a spherical quantum dot with parabolic confinement and in presence of uniform magnetic field. By solving the Schrödinger equation in effective mass and envelope function approximations, eigen-functions and eigen-energies and laws of transitions are acquired. By using eigen-functions and eigen-energies, the differential cross-section (DCS) of electron Raman scattering (ERS) is obtained. DCS is plotted a function of scattering frequency, for different transitions, emission light polarization and sizes of quantum dot.
Noniterative three-dimensional grid generation using parabolic partial differential equations
NASA Technical Reports Server (NTRS)
Edwards, T. A.
1985-01-01
A new algorithm for generating three-dimensional grids has been developed and implemented which numerically solves a parabolic partial differential equation (PDE). The solution procedure marches outward in two coordinate directions, and requires inversion of a scalar tridiagonal system in the third. Source terms have been introduced to control the spacing and angle of grid lines near the grid boundaries, and to control the outer boundary point distribution. The method has been found to generate grids about 100 times faster than comparable grids generated via solution of elliptic PDEs, and produces smooth grids for finite-difference flow calculations.
Compound parabolic concentrator optical fiber tip for FRET-based fluorescent sensors
NASA Astrophysics Data System (ADS)
Ul Hassan, Hafeez; Nielsen, Kristian; Aasmul, Soren; Bang, Ole
2015-09-01
The Compound Parabolic Concentrator (CPC) optical fiber tip shape has been proposed for intensity based fluorescent sensors working on the principle of FRET (Förster Resonance Energy Transfer). A simple numerical Zemax model has been used to optimize the CPC tip geometry for a step-index multimode polymer optical fiber for an excitation and emission wavelength of 550 nm and 650nm, respectively. The model suggests an increase of a factor of 1.6 to 4 in the collected fluorescent power for an ideal CPC tip, as compared to the plane-cut fiber tip for fiber lengths between 5 and 45mm.
Gajic, M; Karwa, N; Mojiri, A; Rosengarten, G
2015-06-01
Linear compound parabolic concentrators with cylindrical receivers are often combined with evacuated tubes along their focal length to suppress convective heat loss for use as thermal collectors. When investigating the optical efficiency of such collectors it is important to consider the reflection loss introduced by the evacuated tube particularly at large angles of incidence of light onto the CPC aperture. In this paper reflection losses are determined using ray-tracing as a function of the angle of incidence in both the longitudinal and transversal planes of a CPC. The reflection losses are found to be approximately constant except close to the maximum acceptance angle. PMID:26072874
A nonlinear parabolic equation with discontinuity in the highest order and applications
NASA Astrophysics Data System (ADS)
Chen, Robin Ming; Liu, Qing
2016-01-01
In this paper we establish a viscosity solution theory for a class of nonlinear parabolic equations with discontinuities of the sign function type in the second derivatives of the unknown function. We modify the definition of classical viscosity solutions and show uniqueness and existence of the solutions. These results are related to the limit behavior for the motion of a curve by a very small power of its curvature, which has applications in image processing. We also discuss the relation between our equation and the total variation flow in one space dimension.
A family of stadium-like billiards with parabolic boundaries under scaling analysis
NASA Astrophysics Data System (ADS)
Livorati, André L. P.; Loskutov, Alexander; Leonel, Edson D.
2011-04-01
Some chaotic properties of a family of stadium-like billiards with parabolic focusing components, which is described by a two-dimensional nonlinear area-preserving map, are studied. Critical values of billiard geometric parameters corresponding to a sudden change of the maximal Lyapunov exponent are found. It is shown that the maximal Lyapunov exponent obtained for chaotic orbits of this family is scaling invariant with respect to the control parameters describing the geometry of the billiard. We also show that this behavior is observed for a generic one-parameter family of mapping with the nonlinearity given by a tangent function.
Xu, Wenjun; Tang, Chen; Zhang, Junjiang; Su, Yonggang; Su, Ray Kai Leung
2015-05-20
Oriented partial differential equation (OPDE)-based filtering methods have been demonstrated to be a powerful tool for denoising while preserving all fringes. In this paper we propose new OPDE-filtering models, named parabolic-hyperbolic oriented partial differential equations (PH-OPDEs), based on variational methods. We test the proposed PH-OPDEs on two computer-simulated and two experimentally obtained ESPI fringe patterns with poor quality, and compare our models with related OPDE models. The experimental results have demonstrated that the new models have significantly better performance in numerical stability and computational efficiency as compared with the previous OPDE models. PMID:26192506
A new explicit method for the numerical solution of parabolic differential equations
NASA Technical Reports Server (NTRS)
Satofuka, N.
1983-01-01
A new method is derived for solving parabolic partial differential equations arising in transient heat conduction or in boundary-layer flows. The method is based on a combination of the modified differential quadrature (MDQ) method with the rational Runge-Kutta time-integration scheme. It is fully explicit, requires no matrix inversion, and is stable for any time-step for the heat equations. Burgers equation and the one- and two-dimensional heat equations are solved to demonstrate the accuracy and efficiency of the proposed algorithm. The present method is found to be very accurate and efficient when results are compared with analytic solutions.
Bramble, J. H.; Pasciak, J. E.; Sammon, P. H.; Thomee, V.
1989-04-01
Backward difference methods for the discretization of parabolic boundary value problems are considered in this paper. In particular, we analyze the case when the backward difference equations are only solved 'approximately' by a preconditioned iteration. We provide an analysis which shows that these methods remain stable and accurate if a suitable number of iterations (often independent of the spatial discretization and time step size) are used. Results are provided for the smooth as well as nonsmooth initial data cases. Finally, the results of numerical experiments illustrating the algorithms' performance on model problems are given.
Finite-horizon optimal investment with transaction costs: A parabolic double obstacle problem
NASA Astrophysics Data System (ADS)
Dai, Min; Yi, Fahuai
This paper concerns optimal investment problem of a CRRA investor who faces proportional transaction costs and finite time horizon. From the angle of stochastic control, it is a singular control problem, whose value function is governed by a time-dependent HJB equation with gradient constraints. We reveal that the problem is equivalent to a parabolic double obstacle problem involving two free boundaries that correspond to the optimal buying and selling policies. This enables us to make use of the well-developed theory of obstacle problem to attack the problem. The C regularity of the value function is proven and the behaviors of the free boundaries are completely characterized.
Binotti, M.; Zhu, G.; Gray, A.; Manzollini, G.
2012-04-01
An analytical approach, as an extension of one newly developed method -- First-principle OPTical Intercept Calculation (FirstOPTIC) -- is proposed to treat the geometrical impact of three-dimensional (3-D) effects on parabolic trough optical performance. The mathematical steps of this analytical approach are presented and implemented numerically as part of the suite of FirstOPTIC code. In addition, the new code has been carefully validated against ray-tracing simulation results and available numerical solutions. This new analytical approach to treating 3-D effects will facilitate further understanding and analysis of the optical performance of trough collectors as a function of incidence angle.
Algorithm to refine a finite volume mesh admissible for parabolic problems
NASA Astrophysics Data System (ADS)
Hubert, Florence; Viallon, Marie-Claude
2009-02-01
We present a simple algorithm to refine a finite volume bidimensional mesh admissible to solve elliptic or parabolic partial differential equations. The approximation of the Laplace operator reduces to the one of the normal fluxes along the edges of control volumes. These normal fluxes can be computed in a consistent way by a classical two points flux approximation simple if the mesh is admissible in the finite volume sense. The originality of the mesh refinement technique that we propose, is to preserve the admissibility property of the meshes. Therefore it can be used in a wide classic context. To cite this article: F. Hubert, M.-C. Viallon, C. R. Mecanique 337 (2009).
NASA Technical Reports Server (NTRS)
Rosen, I. G.
1988-01-01
An abstract approximation and convergence theory for the closed-loop solution of discrete-time linear-quadratic regulator problems for parabolic systems with unbounded input is developed. Under relatively mild stabilizability and detectability assumptions, functional analytic, operator techniques are used to demonstrate the norm convergence of Galerkin-based approximations to the optimal feedback control gains. The application of the general theory to a class of abstract boundary control systems is considered. Two examples, one involving the Neumann boundary control of a one-dimensional heat equation, and the other, the vibration control of a cantilevered viscoelastic beam via shear input at the free end, are discussed.
Investigation of Q-tubes stability using the piecewise parabolic potential
E. Nugaev; A. Shkerin
2014-07-28
We analyze the classical stability of Q-tubes --- charged extended objects in $(3+1)$-dimensional complex scalar field theory. Explicit solutions were found analytically in the piecewise parabolic potential. Our choice of potential allows us to construct a powerful method of stability investigation. We check that in the case of the zero winding number $n=0$, the previously known stability condition $\\partial^2E/\\partial Q^21$ becomes unstable towards the decay into the $n$ vortices with the single winding number.
Doc, Jean-Baptiste; Lihoreau, Bertrand; Félix, Simon; Faure, Cédric; Dubois, Guillaume
2015-01-01
A three-dimensional wide-angle parabolic equation (3DPE) is used to model low frequency sound propagation in irregular urban canyons at low computational cost. This one-way wave equation is solved using the Alternating Direction Implicit method. A finite difference scheme adapted to the geometry of the urban environment is then developed. Abrupt variations of the street width are treated as a single scattering problem using the Kirchhoff approximation. Numerical results are compared with experimental data obtained on a scale model of a street. Comparisons show the ability of the 3DPE model to provide reliable transmitted fields even for large irregularities. PMID:25618062
NASA Astrophysics Data System (ADS)
Masalovich, S.
2014-11-01
An extraordinary focusing property of a parabolic mirror for ultracold neutrons in the presence of the gravitational field was first reported by Steyerl and co-authors. It was shown that all neutrons emitted from the focus of the mirror will be reflected back upon the same focus passing a point of return in the gravitational field in between. The present note offers a complementary geometric proof of this feature and discusses its application to many-mirror systems. The results can also be applied to electrons and ions in an electric field.
NASA Technical Reports Server (NTRS)
1980-01-01
Solar Energy's solar panels are collectors for a solar energy system which provides heating for a drive-in bank in Akron, OH. Collectors were designed and manufactured by Solar Energy Products, a firm established by three former NASA employees. Company President, Frank Rom, an example of a personnel-type technology transfer, was a Research Director at Lewis Research Center, which conducts extensive solar heating and cooling research, including development and testing of high-efficiency flat-plate collectors. Rom acquired solar energy expertise which helped the company develop two types of collectors, one for use in domestic/commercial heating systems and the other for drying grain.
Ray tracing optical analysis of offset solar collector for Space Station solar dynamic system
NASA Technical Reports Server (NTRS)
Jefferies, Kent S.
1988-01-01
OFFSET, a detailed ray tracing computer code, was developed at NASA Lewis Research Center to model the offset solar collector for the Space Station solar dynamic electric power system. This model traces rays from 50 points on the face of the sun to 10 points on each of the 456 collector facets. The triangular facets are modeled with spherical, parabolic, or toroidal reflective surface contour and surface slope errors. The rays are then traced through the receiver aperture to the walls of the receiver. Images of the collector and of the sun within the receiver produced by this code provide insight into the collector receiver interface. Flux distribution on the receiver walls, plotted by this code, is improved by a combination of changes to aperture location and receiver tilt angle. Power loss by spillage at the receiver aperture is computed and is considerably reduced by using toroidal facets.
Ray tracing optical analysis of offset solar collector for space station solar dynamic system
NASA Technical Reports Server (NTRS)
Jefferies, Kent S.
1988-01-01
OFFSET, a detailed ray tracing computer code, was developed at NASA Lewis Research Center to model the offset solar collector for the Space Station solar dynamic electric power system. This model traces rays from 50 points on the face of the Sun to 10 points on each of the 456 collector facets. The triangular facets are modeled with spherical, parabolic, or toroidal reflective surface contour and surface slope errors. The rays are then traced through the receiver aperture to the walls of the receiver. Images of the collector and of the Sun within the receiver produced by this code provide insight into the collector receiver interface. Flux distribution on the receiver walls, plotted by this code, is improved by a combination of changes to aperture location and receiver tilt angle. Power loss by spillage at the receiver aperture is computed and is considerably reduced by using toroidal facets.
Solar tests of aperture plate materials for solar thermal dish collectors
NASA Technical Reports Server (NTRS)
Jaffe, L. D.
1983-01-01
In parabolic dish solar collectors, walk-off of the spot of concentrated sunlight is a hazard if a malfunction causes the concentrator to stop following the Sun. Therefore, a test program was carried out to evaluate the behavior of various ceramics, metals, and polymers under solar irradiation of about 7000 kW/sq m. (peak) for 15 minutes. The only materials that did not slump or shatter were two grades of medium-grain extruded graphite. High purity, slip-cast silica might be satisfactory at somewhat lower flux. Oxidation of the graphite appeared acceptable during tests simulating walk-off, acquisition (2000 cycles on/off Sun), and spillage (continuous on-Sun operation).
NASA Astrophysics Data System (ADS)
Li, Xing; Zhou, Yue-Ting; Zhong, Zheng
2015-04-01
This work presents the analytical solution of sliding contact problem of piezoelectric materials under the action of a flat or parabolic indenter. Inside the contact region, the indenter and the piezoelectric materials are in relative motion. Boundary conditions are well equipped. For a flat indenter and a parabolic indenter, non-classical singularity is presented and exact results are derived for surface contact stress, in-plane stress and electric displacement. Figures show that the influence of the friction coefficient on the stress components is more pronounced than that of the piezoelectric coefficient ratio, while the opposite trend is observed for the electric displacement. Under a sliding parabolic indenter, an increasing of the piezoelectric coefficient ratio makes the contact region become narrower.
Ihn, Thomas
interaction effects beyond the mean field Har- tree and exchange interactions are neglected. Our samplesTwo-subband quantum Hall effect in parabolic quantum wells C. Ellenberger,1 B. Simovic,1 R. Leturcq; published 8 November 2006 The low-temperature magnetoresistance of parabolic quantum wells displays
NASA Astrophysics Data System (ADS)
Ridene, Rym; Mastrour, Nouha; Gamra, Dhouha; Bouchriha, Habib
2015-11-01
In this paper, dispersion energies of Wannier-Mott, Frenkel and mixed exciton formation at the interface in nanocomposite organic-inorganic parabolic quantum dots are investigated theoretically taking account of the interaction between the two excitonic states and electric field effect. Illustration is given for three nanocomposites highly studied experimentally, such as organic P3HT combined respectively with inorganic (CdSe, ZnSe, ZnO) parabolic quantum dots. It is shown that the parameter governing the interaction between the individual exciton states depends on the inorganic quantum dot and can be controlled by the electric field. The results are consistent with the available experimental data.
NASA Technical Reports Server (NTRS)
Mcaninch, G. L.; Myers, M. K.
1980-01-01
The parabolic approximation for the acoustic equations of motion is applied to the study of the sound field generated by a plane wave at or near grazing incidence to a finite impedance boundary. It is shown how this approximation accounts for effects neglected in the usual plane wave reflection analysis which, at grazing incidence, erroneously predicts complete cancellation of the incident field by the reflected field. Examples are presented which illustrate that the solution obtained by the parabolic approximation contains several of the physical phenomena known to occur in wave propagation near an absorbing boundary.
Burke, Jan; Wang, Kai; Bramble, Adam
2009-03-01
We demonstrate the precise figure measurement of a one-inch (25.4 mm) diamond-turned 90 masculine off-axis commercial-quality parabolic mirror. The test is carried out with a phase-shifting Fizeau interferometer fitted with a spherical reference surface, auxiliary components and a flat return mirror. We present a detailed and systematic appraisal of the necessary steps for alignment and calibration of the instrument and the alignment of the parabolic mirror. Alignment errors and interferometric sensitivity variations are characterised and corrected, and the results give some insight into the diamond-turning process. PMID:19259157
Atmospheric Science Data Center
2014-09-25
... (kWh/m2/day) Amount of electromagnetic energy (solar radiation) incident on the surface of the earth. Also referred to as total or global solar radiation. Midday insolation (kWh/m2/day) Average ...
Atmospheric Science Data Center
2014-09-25
Solar Noon (GMT time) The time when the sun is due south in the northern hemisphere or due north in the southern ... The average cosine of the angle between the sun and directly overhead during daylight hours. Cosine solar ...
Elastic parabolic equation solutions for underwater acoustic problems using seismic sources.
Frank, Scott D; Odom, Robert I; Collis, Jon M
2013-03-01
Several problems of current interest involve elastic bottom range-dependent ocean environments with buried or earthquake-type sources, specifically oceanic T-wave propagation studies and interface wave related analyses. Additionally, observed deep shadow-zone arrivals are not predicted by ray theoretic methods, and attempts to model them with fluid-bottom parabolic equation solutions suggest that it may be necessary to account for elastic bottom interactions. In order to study energy conversion between elastic and acoustic waves, current elastic parabolic equation solutions must be modified to allow for seismic starting fields for underwater acoustic propagation environments. Two types of elastic self-starter are presented. An explosive-type source is implemented using a compressional self-starter and the resulting acoustic field is consistent with benchmark solutions. A shear wave self-starter is implemented and shown to generate transmission loss levels consistent with the explosive source. Source fields can be combined to generate starting fields for source types such as explosions, earthquakes, or pile driving. Examples demonstrate the use of source fields for shallow sources or deep ocean-bottom earthquake sources, where down slope conversion, a known T-wave generation mechanism, is modeled. Self-starters are interpreted in the context of the seismic moment tensor. PMID:23464007
Development of a finite element model for the simulation of parabolic impact of sandwich panels
NASA Astrophysics Data System (ADS)
Ram Ramakrishnan, Karthik; Guérard, Sandra; Mahéo, Laurent; Shankar, Krishna; Viot, Philippe
2015-09-01
Sandwich panels are lightweight structures of two thin high strength facesheets bonded to either side of a thick low density core such as foams and honeycombs. It is necessary to study the impact response of sandwich structures in order to ensure the reliability and safety of these structures. The response of sandwich panels to impact loading is usually studied for impact at normal angle of incidence. In real engineering situations, the structures are more frequently loaded at some oblique angle or with a complex trajectory. It is easy to carry out normal impact tests using devices like the drop tower, but impacts at oblique angles are difficult to characterise experimentally. A tri-dimensional impact device called Hexapod has been developed to experimentally study the impact loading of sandwich plates with a parabolic trajectory. The Hexapod is a modified Gough-Stewart platform that can be moved independently in the six degrees of freedom, corresponding to three translation axes and three rotation axes. In this paper, an approach for modelling the parabolic impact of sandwich structures with thin metallic facesheets and polymer foam core using commercial finite element code LS-DYNA software is presented. The results of the FE model of sandwich panels are compared with experimental data in terms of the time history of vertical and horizontal components of force. A comparison of the strain history obtained from Digital Image Correlation and LS-Dyna model are also presented.
Parabolic Flight Evaluation of Bacterial Adhesion on Multiple Antimicrobial Surface Treatments
NASA Technical Reports Server (NTRS)
Birmele, Michele
2011-01-01
This report describes the development of a test method and the evaluation of the effectiveness of antimicrobial technologies in reduced gravity based on parabolic flight experiments. Microbial growth is a common occurrence on fully immersed wetted surfaces in spacecraft environmental control and life support systems despite the use of chemical and/or physical \\disinfection. Many materials and surface treatments with antimicrobial properties are commercially available but none have been vetted for spaceflight applications. Herein a test method is explained that included ground and reduced gravity parabolic flight experiments with a standard microorganism recovered from spacecraft, Pseudomonas aeruginosa, added at a concentration of 1 x 10(exp 5) cells per milliliter (mL) onto challenge material coupon surfaces. Several experimental materials were observed to slightly reduce microbial attachment in reduced gravity flight experiments, but none were capable of eliminating all challenge bacteria. Lunar gravity had an increased antimicrobial effect in 28 out of 36 test coupons compared to microgravity when provided otherwise identical conditions for growth, suggesting trace .amounts of gravity may be required for maximum antimicrobial performance. Bacterial cells exposed to variable gravity had more than twice as ,much intracellular adenosine triphosphate (ATP) when compared to control cells exposed only to Earth gravity due to a short duration response to environmental stress. An ATP luminescence assay was the method most amenable to development of an in-flight microbial monitoring assay