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1

Solar Cooker  

NSDL National Science Digital Library

Learners build a simple solar oven from a shoebox, black construction paper, and aluminum foil. Over the course of a few hours, the oven heats up water enough to brew tea. When learners set up a free account at Kinetic City, they can answer bonus questions at the end of the activity as a quick assessment. As a larger assessment, learners can complete the Smart Attack game after they've completed several activities.

American Association for the Advancement of Science

2009-01-01

2

Solar Cookers International  

NSDL National Science Digital Library

With diminishing supplies of firewood in many impoverished nations, how can rural people cook food for their families? In 1987, 17 solar cooking Californians started Solar Cookers International (SCI), and produced manuals on how to produce and use a simple solar box cooker. Since then, 30,000 families in eastern and southern Africa have learned to use solar cooking with the assistance of SCI. Visitors should definitely check out the ten-minute video on the homepage that explains the spread of the use of the solar cooker in Africa, which began in refugee camps where food had to be cooked for tens of thousands of people. Eventually, its use spread to rural villages, but the video explains it has been a slow process. Visitors interested in the Solar Review Cooker e-newsletter that is published thrice-yearly can sign up to receive it free, under the "Newsletter" tab. It is also available in dozens of languages, including French, Arabic, and Chinese.

3

Performance evaluation of three solar concentrating cookers  

Microsoft Academic Search

Three solar concentrating type cookers meant for domestic use were tested for their thermal performance and cooking abilities. Stagnation temperature, water heating and cooking tests were conducted. During the tests, the operational ease and problems in each cooker were evaluated.

N. V Patel; S. K Philip

2000-01-01

4

Solar box cookers and geothermal energy  

SciTech Connect

A major amount of world-wide forest depletion is caused by harvesting cooking wood. Solar box cookers can help to ameliorate this situation in that they use solar energy instead of wood to cook food. Usable year-round in the tropics and for 6 to 8 months of the year in most sunny areas of the world, the cookers can cook almost anything if there is 15 minutes of sunshine every hour. Developed in 1976 solar box cookers represent a major advance over early solar cookers. Solar box cookers are about the size of an ice chest, easily constructed by the users themselves and inexpensive. The cookers are made of cardboard or wood, and aluminum foil. Each box is topped with a sheet of glass above which an adjustable reflective lid is positioned to angle in sunlight. The food cooks in covered, dark-colored pans. One cooker can cook 10-15 pounds of food in three to five hours. Fruits, vegetables, meats, and any baked goods can be prepared, and water and milk pasteurized in them. The coking food does not have to be stirred and will not burn. The developer is also looking for ways the geothermal community could interface with solar box cookers.

Not Available

1988-12-01

5

Solar Cooker Pringles Can Lesson  

NSDL National Science Digital Library

This classroom learning unit gives students hands-on experience using solar energy. The class will use a Pringles can to cook a hot dog using solar energy. In addition to introducing a practical application of solar energy, this unit will also allow students to think about how clean, renewable energy may be used by people in developing countries. This document may be downloaded in PDF file format.

Orzali, Joe

2011-12-12

6

A solar box cooker for mass production in East Africa  

SciTech Connect

A solar box cooker produced in Tanzania, East Africa with indigenous materials is described. When compared to a commercially produced glass and cardboard one, it was found to perform as well. Heat transfer through each major component of the cooker is presented. The smallest losses were through the walls of the box. The greatest losses were observed in the cover system.

Funk, P.A.; Wilcke, W.F. [Univ. of Minnesota, St. Paul, MN (United States). Dept. of Agricultural Engineering

1992-12-31

7

Solar thermal collector system modeling and testing for novel solar cooker  

E-print Network

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 ...

Foley, Brian, S.B. (Brian M.). Massachusetts Institute of Technology

2014-01-01

8

Development of an asynchronous solar-powered cooker  

E-print Network

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 ...

Akinwale, P. Femi (Pamela Femi)

2006-01-01

9

SOLAR COOKER UTILIZING SATELLITE DISH TECHNOLOGY Mechanical Engineering Department , Philadelphia University, Amman Jordan, e-mail  

E-print Network

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

10

Cookin' with Sun: Design and Build Solar Cookers  

ERIC Educational Resources Information Center

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

Brand, Lance; Warren, Ande; Fitzgerald, Mike

2006-01-01

11

Solar cooking in Switzerland--Use of cookers in Africa and India  

SciTech Connect

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.

Pulfer, J. [Group ULOG, Basel (Switzerland)

1992-12-31

12

Shenandoah parabolic dish solar collector  

SciTech Connect

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.

Kinoshita, G.S.

1985-01-01

13

Twelve years experience with solar cookers: Necessary tools for a clean environment  

SciTech Connect

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.

Nandwani, S.S. [Univ. Nacional Herida (Costa Rica). Dept. de Fisica

1992-12-31

14

Plane and parabolic solar panels  

E-print Network

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.

J. H. O. Sales; A. T. Suzuki

2009-05-14

15

Plane and parabolic solar panels  

Microsoft Academic Search

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.

J. H. O. Sales; A. T. Suzuki

2009-01-01

16

Plane and parabolic solar panels  

Microsoft Academic Search

We present a plane and parabolic collector that absorbs radiant energy and\\u000atransforms it in heat. Therefore we have a panel to heat water. We study how to\\u000aincrement this capture of solar beams onto the panel in order to increase its\\u000aefficiency in heating water.

J. H. O. Sales; A. T. Suzuki

2009-01-01

17

First and Second Law Efficiencies in the Cooking Process of Eggplant using a Solar Cooker Box-Type  

NASA Astrophysics Data System (ADS)

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.

Terres, H.; Chvez, S.; Lizardi, A.; Lpez, R.; Vaca, M.; Flores, J.; Salazar, A.

2015-01-01

18

Solar Parabolic Dish Annual Technology Evaluation Report  

NASA Technical Reports Server (NTRS)

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.

1983-01-01

19

Heat Transfer Convection in The Cooking of Apple Using a Solar Cooker Box-Type  

NASA Astrophysics Data System (ADS)

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.

Terres, H.; Chvez, S.; Lizardi, A.; Lpez, R.; Vaca, M.; Flores, J.; Salazar, A.

2015-01-01

20

Design, fabrication, and testing of a mechanical timer in application of a stored-heat solar cooker  

E-print Network

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 ...

Hsu, Julia C

2014-01-01

21

Building a parabolic solar concentrator prototype  

NASA Astrophysics Data System (ADS)

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.

Escobar-Romero, J. F. M.; Montiel, S. Vzquez y.; Granados-Agustn, F.; Cruz-Martnez, V. M.; Rodrguez-Rivera, E.; Martnez-Yez, L.

2011-01-01

22

Parabolic trough solar collectors : design for increasing efficiency  

E-print Network

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 ...

Figueredo, Stacy L. (Stacy Lee), 1981-

2011-01-01

23

Simplified Methodology for Designing Parabolic Trough Solar Power Plants  

Microsoft Academic Search

The performance of parabolic trough based solar power plants over the last 25 years has proven that this technology is an excellent alternative for the commercial power industry. Compared to conventional power plants, parabolic trough solar power plants produce significantly lower levels of carbon dioxide, although additional research is required to bring the cost of concentrator solar plants to a

Ricardo Vasquez Padilla

2011-01-01

24

USE OF THE SOLAR PANEL COOKER FOR MEDICAL PRESSURE STEAM STERILIZATION  

Microsoft Academic Search

The expense, unreliability or unavailability of fuel and electricity in many areas hampers the ability of medical facilities to autoclave implements and supplies. This paper describes the adaptation of a large, simple, low- cost panel cooker to greatly reduce the reliance on conventional heat sources. The hybrid apparatus integrates propane for backup in case the available sunlight is insufficient. In

Barbara Prosser Kerr; James Scott

25

Steam engine research for solar parabolic dish  

NASA Technical Reports Server (NTRS)

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.

Demler, R. L.

1981-01-01

26

Mechanism of Hydrogen Formation in Solar Parabolic Trough Receivers  

Microsoft Academic Search

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

L. Moens; D. M. Blake

2008-01-01

27

Test results, Industrial Solar Technology parabolic trough solar collector  

SciTech Connect

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.

Dudley, V.E. [EG and G MSI, Albuquerque, NM (United States); Evans, L.R.; Matthews, C.W. [Sandia National Labs., Albuquerque, NM (United States)

1995-11-01

28

Federal technology alert. Parabolic-trough solar water heating  

SciTech Connect

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.

NONE

1998-04-01

29

Cooking with the Sun. How To Build and Use Solar Cookers.  

ERIC Educational Resources Information Center

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

Halacy, Beth; Halacy, Dan

30

Gas Turbine/Solar Parabolic Trough Hybrid Designs: Preprint  

SciTech Connect

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.

Turchi, C. S.; Ma, Z.; Erbes, M.

2011-03-01

31

Parabolic Dish Solar Thermal Power Annual Program Review Proceedings  

NASA Technical Reports Server (NTRS)

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.

Lucas, J. W.

1982-01-01

32

Thermal design of compound parabolic concentrating solar-energy collectors  

Microsoft Academic Search

A theoretical analysis of the heat exchanges in a Compound Parabolic Concentrator solar energy collector is presented. The absorber configuration considered is that of a tube (with or without a spectrally-selective surface) either directly exposed or enclosed within one or two glass envelopes. The annular cavity formed between the tube and the surrounding envelope can be either air-filled or evacuated.

D. E. Prapas; B. Norton; S. D. Probert

1987-01-01

33

Beaming-In On Student-Made Solar Technology  

ERIC Educational Resources Information Center

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)

Chiotelis, Charles L.

1978-01-01

34

Thermal design of parabolic solar concentrator adsorption refrigeration system  

Microsoft Academic Search

This study presents a thermal design of solar-powered adsorption refrigeration with the type of activated carbon-methanol\\u000a pair. The designed module consists of an evacuated glass tube equipped with a parabolic solar concentrator as generator, sorption\\u000a bed, evaporator, and condenser units. A thermodynamic design procedure and a mathematical model of a steady state system with\\u000a activated carbon refrigerator have been developed.

G. M. Tashtoush; M. Jaradat; S. Al-Bader

2010-01-01

35

Thermal analysis of solar parabolic trough with porous disc receiver  

Microsoft Academic Search

In this paper, 3-D numerical analysis of the porous disc line receiver for solar parabolic trough collector is presented. The influence of thermic fluid properties, receiver design and solar radiation concentration on overall heat collection is investigated. The analysis is carried out based on renormalization-group (RNG) k? turbulent model by using Therminol-VP1 as working fluid. The thermal analysis of the

K. Ravi Kumar; K. S. Reddy

2009-01-01

36

Solar box cookers: Towards a decentralized sustainable energy strategy for sub-Saharan Africa  

Microsoft Academic Search

The continued economic decline of sub-Saharan Africa, and the African energy crisis in particular, have received considerable attention in recent literature. Little attention, however, has been given to the assessment of solar power as an environmentally sound and economically viable energy strategy. Considering the increasing fuelwood scarcity and debt incurred through petroleum imports, solar energy provides a welcome alternative to

Ellie R. Carmody; Amin U. Sarkar

1997-01-01

37

Absorber Alignment Measurement Tool for Solar Parabolic Trough Collectors: Preprint  

SciTech Connect

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.

Stynes, J. K.; Ihas, B.

2012-04-01

38

Irrigation market for solar thermal parabolic dish systems  

NASA Technical Reports Server (NTRS)

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.

Habib-Agahi, H.; Jones, S. C.

1981-01-01

39

Proceedings: Fourth Parabolic Dish Solar Thermal Power Program Review  

NASA Technical Reports Server (NTRS)

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.

1983-01-01

40

hal-00177601,version2-30Oct2007 A closed parabolic trough solar collector  

E-print Network

by an electronic tracking system, so that the solar radiations are reflected by the mirrors to ahal-00177601,version2-30Oct2007 A closed parabolic trough solar collector Gang Xiao 30th October 2007 Parabolic trough[1] is the most mature technology for large scale exploitation of solar energy

Paris-Sud XI, Université de

41

Analytic modeling of a solar power plant with parabolic linear collectors  

Microsoft Academic Search

An analytic model for a solar thermal electric generating system with parabolic trough collectors was developed. The energy conversion of solar radiation into thermal power along the absorber tube of the parabolic collector is studied, taking into consideration the non-linearity of heat losses and its dependence on the local temperature. The coupling between the collector and the thermodynamic cycle is

Milton Matos Rolim; Naum Fraidenraich; Chigueru Tiba

2009-01-01

42

Fifth parabolic dish solar thermal power program annual review: proceedings  

SciTech Connect

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.

None

1984-03-01

43

Optical characterization of solar furnace system using fixed geometry nonimaging focusing heliostat and secondary parabolic concentrator  

Microsoft Academic Search

A novel solar furnace system has been proposed to be consisted of a Nonimaging Focusing Heliostat and a smaller parabolic concentrator. In this configuration, the primary heliostat consists of 1111 array of concave mirrors with a total reflective area of 121 m2 while the secondary parabolic concentrator has a focal length of 30 cm. To simplify the design and reduce

Kok-Keong Chong; Chuan-Yang Lim; Wee-Liang Keh; Jian-Hau Fan; Faidz Abdul Rahman

2011-01-01

44

THE GLASS-TO-METAL SEALING PROCESS IN PARABOLIC TROUGH SOLAR RECEIVERS  

Microsoft Academic Search

This paper introduces the structure and components of the receiver tube (HCE) in the parabolic trough solar thermal power system, and presents the technologic difficulty of achieving good glass-to-metal sealing during the process of receiver tube manufacture. The glass-to-metal sealing of HCE failure \\/degradation is the single largest cost factor in the 9 parabolic trough solar power plants in the

Dongqiang Lei; Zhifeng Wang; Fengli Du

45

Slope Error Measurement Tool for Solar Parabolic Trough Collectors: Preprint  

SciTech Connect

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.

Stynes, J. K.; Ihas, B.

2012-04-01

46

Survey Cycle of Linear Parabolic Solar Power Plant; Design & Control of Collectors Efficiency  

Microsoft Academic Search

With taking into special consideration the importance of the competition which exists in the world to utilize new energies; and also in agreement with our country from the viewpoint of superficies and duration of solar radiation, it is necessary to use such energy as much as possible. Therefore, in this article, Shiraz linear parabolic solar power plant has been used

H. Moaveni

2006-01-01

47

Survey Cycle of Linear Parabolic Solar Power Plant; Design & Control of Collectors Efficiency  

Microsoft Academic Search

With taking into special consideration the importance of the competition which exists in the world to utilize new energies; and also in agreement with our country from the viewpoint of superficies and duration of solar radiation, it is necessary to use such energy as much as possible. Therefore, in this article, Shiraz Linear Parabolic Solar Power Plant has been used

Houtan Moaveni

2007-01-01

48

Sandia invention to make parabolic trough solar collector systems more energy efficient  

NSDL National Science Digital Library

This news release, from Sandia National Laboratories, announces the development of a system to align the long parabolic trough mirrors in a solar collector, thereby making it much more efficient. The article contains a description of how such trough solar collector systems and the new mirror alignment devices operate. Images are provided along with an outline of the group's anticipated progress.

2007-09-25

49

A new parabolic trough solar collector P. Kohlenbach1  

E-print Network

) and remote power and energy. The array is designed to drive a small Organic Rankine Cycle unit with a power parabolic trough array designed to provide the thermal energy required to drive a organic rankine cycle (ORC, Canberra ACT 0200 3 Wizard Power, 15 Barry Drive, Turner, ACT, 2612 ABSTRACT This paper presents a new

50

The 3X Compound Parabolic Concentrating (CPC) solar energy collector  

Microsoft Academic Search

A 3X compounds parabolic concentrating (CPC) collector was designed. 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 were integrated with a

R. W. Ballheim

1980-01-01

51

Enhancing Optical Efficiency of a Linear Parabolic Solar Collector through Nanofluids  

Microsoft Academic Search

This paper explores different types of nanofluids (namely aluminium nanoparticles dispersed in water, ethylene glycol, propylene glycol and therminol VP-1) for their suitability as working fluid in direct absorption linear parabolic solar collectors. Lambert Beer's law has been invoked to compute intensity attenuation as it passes through the nanofluid. Intensity attenuation and subsequent energy transfer takes place through absorption and

Vikrant Khullar; Himanshu Tyagi

2011-01-01

52

Analysis of the influence of geography and weather on parabolic trough solar collector design. [SOLTES code  

SciTech Connect

The potential performance of single-axis tracking parabolic trough solar collectors as a function of optical energy distribution and receiver size has been calculated for eleven sites using typical meteorological year input data. A simulation based on the SOLTES code was developed which includes the three-dimensional features of a parabolic trough and calculates the thermooptical tradeoffs. The capability of the thermooptical model has been confirmed by the comparison of calculated results with the experimental results from an all-day test of a parabolic trough. The results from this eleven-site analysis indicate a potential performance superiority of a north-south horizontal axis trough and, in addition, a high quality collector should be of the same geometric design for all of the sites investigated and probably for all regions of the country.

Treadwell, G.W.; Grandjean, N.R.; Biggs, F.

1980-08-01

53

Analysis of the influence of geography and weather on parabolic trough solar collector design  

SciTech Connect

The potential performance of single-axis tracking parabolic trough solar collectors as a function of optical energy distribution and receiver size has been calculated for eleven sites using typical meteorological year input data. A simulation based on the SOLTES code was developed which includes the three-dimensional features of a parabolic trough and calculates the thermooptical tradeoffs. The capability of the thermooptical model has been confirmed by the comparison of calculated results with the experimental results from an all-day test of a parabolic trough. The results from this eleven-site analysis indicate a potential performance superiority of a north-south horizontal axis trough and, in addition, a high quality (optical error, sigma/sub system/ less than or equal to 0.007 radian) collector should be of the same geometric design for all of the sites investigated and probably for all regions of the country.

Treadwell, G.W.; Grandjean, N.R.; Biggs, F.

1980-03-01

54

Performance and economics of a solar thermal power generation plant in Jubail, Saudi Arabia: Parabolic trough collector  

Microsoft Academic Search

The study explores the technical and economic feasibility of a thermal solar power generation plant using parabolic trough collectors (Euro Trough) in Jubail Industrial City, Saudi Arabia. Total annual available solar radiation is calculated at 1,970 kWhr. The size of the proposed solar thermal power plant is 50 MW. The designed solar field is composed of 100 loops with a

Adel M. Al-Nasser

2010-01-01

55

Near-parabolic cometary flux in the outer solar system  

NASA Astrophysics Data System (ADS)

The flux of near-parabolic comets in the outer planetary region is calculated by adopting the regularized equation of motion which incorporates planetary and galactic perturbations. It is found that the flux is similar to the case of a strong comet shower, derived on the presumption that the Galactic tidal force is not operative. The flux so calculated, together with the capture probability of short-period (SP) comets, makes it possible to estimate the supply rate of SP comets. The estimated rate is 0.002/yr, which is at least one order of magnitude less than that required by observation. Possible sources of SP comets are discussed such as a disintegration of a giant comet, an inner extension of the observed Oort cloud, or the Kuiper belt.

Yabushita, S.; Tsujii, T.

1991-01-01

56

Modeling of a Parabolic Trough Solar Field for Acceptance Testing: A Case Study  

SciTech Connect

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.

Wagner, M. J.; Mehos, M. S.; Kearney, D. W.; McMahan, A. C.

2011-01-01

57

Some modifications to the design of a parabolic solar concentrator for construction in Lesotho and their effects on power production  

E-print Network

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 ...

Ferreira, Toni (Toni Jolene)

2005-01-01

58

Gas Turbine/Solar Parabolic Trough Hybrid Design Using Molten Salt Heat Transfer Fluid: Preprint  

SciTech Connect

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.

Turchi, C. S.; Ma, Z.

2011-08-01

59

Measured performances of curved inverted-vee, absorber compound parabolic concentrating solar-energy collectors  

Microsoft Academic Search

The design and thermal performance of modified compound parabolic concentrating (CPC) solar-energy collectors are described. The designs incorporate a curved inverted-Vee absorber fin, which allows a reflector of simple geometry to be used. This CPC collector, has exhibited a superior performance to that of a conventional cusp-reflector CPC design, owing to the enhancement of the optical efficiency obtained by eliminating

B. Norton; D. E. Prapas; P. C. Eames; S. D. Probert

1989-01-01

60

Solar reforming of methane in a direct absorption catalytic reactor on a parabolic dish  

SciTech Connect

The concept of solar driven chemical reactions in a commercial-scale volumetric receiver/reactor on a parabolic concentrator was successfully demonstrated in the CAtalytically Enhanced Solar Absorption Receiver (CAESAR) test. Solar reforming of methane (CH{sub 4}) with carbon dioxide (CO{sub 2}) was achieved in a 64-cm diameter direct absorption reactor on a parabolic dish capable of 150 kW solar power. The reactor was a catalytic volumetric absorber consisting of a multi-layered, porous alumina foam disk coated with rhodium (Rh) catalyst. The system was operated during both steady-state and solar transient (cloud passage) conditions. The total solar power absorbed reached values up to 97 kW and the maximum methane conversion was 70%. Receiver thermal efficiencies ranged up to 85% and chemical efficiencies peaked at 54%. The absorber performed satisfactorily in promoting the reforming reaction during the tests without carbon formation. However, problems of cracking and degradation of the porous matrix, nonuniform dispersion of the Rh through the absorber, and catalyst deactivation due to sintering and possible encapsulation, must be resolved to achieve long-term operation and eventual commercialization. 17 refs., 11 figs., 1 tab.

Muir, J.F.; Hogan, R.E. Jr.; Skocypec, R.D. (Sandia National Labs., Albuquerque, NM (USA)); Buck, R. (Deutsche Forschungsanstalt fuer Luft- und Raumfahrt e.V. (DLR), Stuttgart (Germany, F.R.). Inst. fuer Technische Thermodynamik)

1990-01-01

61

Experiments with an Induction Cooker  

ERIC Educational Resources Information Center

The induction cooker is a common appliance nowadays. How does it work? Why is it not possible to use aluminium utensils with it? What experiments can be carried out with it (at different levels) and not only in physics lessons? Searching for the answers to these and other questions is the purpose of this article. (Contains 5 figures.)

Zilavy, Peter

2009-01-01

62

Optical characterization of solar furnace system using fixed geometry nonimaging focusing heliostat and secondary parabolic concentrator  

NASA Astrophysics Data System (ADS)

A novel solar furnace system has been proposed to be consisted of a Nonimaging Focusing Heliostat and a smaller parabolic concentrator. In this configuration, the primary heliostat consists of 1111 array of concave mirrors with a total reflective area of 121 m2 while the secondary parabolic concentrator has a focal length of 30 cm. To simplify the design and reduce the cost, fixed geometry of the primary heliostat is adopted to omit the requirement of continuous astigmatic correction throughout a year. The overall performance of the novel solar furnace configuration can be optimized if the heliostat's spinning-axis is fixed in the orientation dependent on the latitude angle so that the annual variation of incidence angle is the least, which ranges from 33 to 57. Case study of the novel solar furnace system has been performed with the use of ray-tracing method to simulate solar flux distribution profile for two different target distances, i.e. 50 m and 100 m. The simulated results have revealed that the maximum solar concentration ratio ranges from 20,530 suns to 26,074 suns for the target distance of 50 m, and ranges from 40,366 suns to 43,297 suns for the target distance of 100 m.

Chong, Kok-Keong; Lim, Chuan-Yang; Keh, Wee-Liang; Fan, Jian-Hau; Rahman, Faidz Abdul

2011-10-01

63

Optimization of spherical facets for parabolic solar concentrators  

NASA Technical Reports Server (NTRS)

Solar concentrator designs which employ deployable hexagonal panels are being developed for space power systems. An offset optical configuration has been developed which offers significant system level advantages over previously proposed collector designs for space applications. Optical analyses have been performed which show offset reflector intercept factors to be only slightly lower than those for symmetric reflectors with the same slope error. Fluxes on the receiver walls are asymmetric but manageable by varying the tilt angle of the receiver. Greater producibility is achieved by subdividing the hexagonal panels into triangular mirror facets of spherical contour. Optical analysis has been performed upon these to yield near-optimum sizes and radii.

White, J. E.; Erikson, R. J.; Sturgis, J. D.; Elfe, T. B.

1986-01-01

64

Cost/performance of solar reflective surfaces for parabolic dish concentrators  

NASA Technical Reports Server (NTRS)

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.

Bouquet, F.

1980-01-01

65

Calculation of the Concentrated Flux Density Distribution in Parabolic Trough Solar Concentrators by Monte Carlo Ray-Trace Method  

Microsoft Academic Search

In this paper, the optical concentration ratio for the parabolic trough solar concentrators (PTSCs), which is a key boundary condition in the heat transfer performance analysis, would be simulated and computed by Monte Carlo Ray-Trace (MCRT) method in different conditions. In the computation process, non-parallelism of solar rays, geometric concentrating ratio and rim angle would be considered. Based on the

Bin Yang; Jun Zhao; Tao Xu; Qiang Zhu

2010-01-01

66

Slow Cookers and Food Safety  

MedlinePLUS

... Administrative Forms Standard Forms Skip Navigation Z7_0Q0619C0JGR010IFST1G5B10H1 Web Content Viewer (JSR 286) Actions ${title} Loading... / Topics / ... Safety / Slow Cookers and Food Safety Z7_0Q0619C0JGR010IFST1G5B10H3 Web Content Viewer (JSR 286) Actions ${title} Loading... Z7_ ...

67

Enhancing Optical Efficiency of a Linear Parabolic Solar Collector through Nanofluids  

NASA Astrophysics Data System (ADS)

This paper explores different types of nanofluids (namely aluminium nanoparticles dispersed in water, ethylene glycol, propylene glycol and therminol VP-1) for their suitability as working fluid in direct absorption linear parabolic solar collectors. Lambert Beer's law has been invoked to compute intensity attenuation as it passes through the nanofluid. Intensity attenuation and subsequent energy transfer takes place through absorption and scattering of solar radiations by the participating media (nanofluid). The current analysis quantitatively compares the solar energy capturing capacity for the four nanofluids. Optical efficiency as a function of receiver radius and volume fraction of nanoparticles has been computed for the four nanofluids, also thermal efficiency as a function of volume fraction has been found out.

Khullar, Vikrant; Tyagi, Himanshu

2011-10-01

68

Test results on parabolic dish concentrators for solar thermal power systems  

NASA Technical Reports Server (NTRS)

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.

Jaffe, Leonard D.

1989-01-01

69

Cleaning strategies for parabolic-trough solar-collector fields; guidelines for decisions  

SciTech Connect

This report is intended to assist the owner or operator of a parabolic trough solar collector system to decide on a cleaning strategy (equipment, materials, procedures, and schedules). The guidelines are based on information obtained in past research studies, as well as interviews with vendors and users of cleaning and water treatment equipment. The basic procedure recommended utilizes high pressure portable washing equipment. However, since the cleaning problem is so site-specific, no single, detailed approach can be specified. A systematic procedure for evaluating the particular requirements of a site is therefore given. This will allow the solar energy system operator to develop a cleaning strategy which is cost-effective because it is suited to local conditions.

Bergeron, K.D.; Freese, J.M.

1981-06-01

70

Life Cycle Assessment of a Parabolic Trough Concentrating Solar Power Plant and Impacts of Key Design Alternatives: Preprint  

Microsoft Academic Search

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

G. A. Heath; J. J. Burkhardt; C. S. Turchi

2011-01-01

71

An overview of the value of parabolic dish solar thermal systems in industrial cogeneration applications  

NASA Technical Reports Server (NTRS)

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.

1982-01-01

72

Utility-Scale Parabolic Trough Solar Systems: Performance Acceptance Test Guidelines, April 2009 - December 2010  

SciTech Connect

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.

Kearney, D.

2011-05-01

73

An anisotropic model of diffuse solar radiation with application to an optimization of compound parabolic collectors  

NASA Astrophysics Data System (ADS)

Based on a simple geometrical description of the sky hemisphere and the magnitude of the horizontal diffuse radiation, a model for estimating diffuse radiation impinging on sloping surfaces was developed. Tests against data show that substantial improvement is achieved over the classical isotropic model for any collector slope or orientation. Improvement is found for instantaneous as well as accumulated data. The application of the model to compound parabolic collectors (CPC) accounts partly for the role played by forward scattered radiation in the total energy they receive. An optimization of CPC's geometrical characteristics is performed for photovoltaic generation in the area of Albany, NY. This calculation is used to assess the relative effects of meteorological conditions and economic assumptions or optimum concentration values, and provides the reader with information pertaining to the variation of the cost of electrical energy produced as a function of the cost of silicon solar cells.

Perez, R. R.

74

Frequency response analysis of fluid control systems for parabolic trough solar collectors  

SciTech Connect

Previous studies of solar collector fluid control systems have utilized computer simulations of collector and piping dynamics to evaluate stability and response characteristics. To obtain reasonable simulation accuracy requires substantial computer memory and time, and is well beyond the capability of small desk-top computers. Here a linearized steady state frequency response is derived for parabolic trough collectors and for connecting piping, which can be used in standard gain-phase analyses to evaluate system stability and closed loop frequency response. The frequency response characteristics of a typical collector string and piping are used in a gain-phase analysis to get some insight into the effect on system stability of various system parameters such as controller gain, sensor and controller time constants, and sensor location.

Schindwolf, R.

1980-01-01

75

Vanguard I solar parabolic dish-Stirling engine module. Final report, May 28, 1982-September 30, 1984  

SciTech Connect

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.

Washom, B.J.

1984-09-30

76

Charcoal-methanol adsorption refrigerator powered by a compound parabolic concentrating solar collector  

SciTech Connect

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]).

Headley, O.StC.; Kothdiwala, A.F.; McDoom, I.A. (Univ. of the West Indies, St. Augustine (Trinidad and Tobago))

1994-08-01

77

The small community solar thermal power experiment. Parabolic dish technology for industrial process heat application  

NASA Technical Reports Server (NTRS)

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.

Polzien, R. E.; Rodriguez, D.

1981-01-01

78

Design of parabolic trough collector solar field for future solar thermal power plants in Algeria  

Microsoft Academic Search

The main future challenge for Algeria is to realize the self-sufficiency from solar electricity and its exportation; because it has the best annual solar potential in the Mediterranean basin, estimated by 169 TWh. Now Algeria has planned a program of capacity 22 000 MW in which the considerable share is renewable origin for horizon 2030. The program includes photovoltaic and

Abdelhafid Moummi

2012-01-01

79

Numerical simulation and design of a parabolic trough solar collector used as a direct generator in a solar-GAX cooling cycle?  

Microsoft Academic Search

In this work, a solar parabolic trough collector (PTC) has been dimensioned and its technical feasibility has been evaluated\\u000a in order to be used as ammonia direct vapor generator in an advanced absorption air-cooled Solar-GAX cycle of 10.6 kW cooling\\u000a capacity. A detailed numerical simulation model that takes into account the geometry and the optical, thermal and fluid dynamic\\u000a behavior

Daniel Sauceda; Nicols Velzquez; Octavio Garca-Valladares; Ricardo Beltrn

2011-01-01

80

New high-flux two-stage optical designs for parabolic solar concentrators  

Microsoft Academic Search

We present a new two-stage optical design for parabolic dish concentrators that can realistically attain close to 90% of the thermodynamic limit to concentration with practical, compact designs (e.g., at parabola rim half-angles of around 45[degrees]). For comparison, the parabolic dish-plus-compound parabolic concentrator secondary design, at this rim angle, achieves no more than 50% of the thermodynamic limit. Our new

R. P. Friedman; J. M. Gordon; H. Ries

1993-01-01

81

Experimental investigation of parabolic-cylinder solar concentration with tubular heat receiver  

SciTech Connect

The focusing characteristics and efficiency are investigated for a parabolic-cylinder concentrator with tubular heat receiver fabricated by elastic deformation of a sheet of electropolished anodized aluminum.

Markman, M.A.; Kolomoets, N.V.; Simanovskii, L.M.; Shmatok, Yu.I.; Zakharova, O.P.

1980-01-01

82

Design options for low cost thermal transport piping networks for point focusing parabolic dish solar thermal systems  

Microsoft Academic Search

Design options are investigated for low-cost thermal transport piping networks that are used to supply heat generated by parabolic dish solar thermal systems to a wide range of thermal applications. These options include (1) working fluids of steam, Therminol, and draw salt; (2) packing factors (reflecting the spacing of dishes) which range from 0.3 to 0.5; and (3) supply and

T. Fujita; W. Revere; J. Biddle; H. Awaya; D. DeFranco

1981-01-01

83

Comparison of advanced thermal and electrical storage for parabolic dish solar thermal power systems  

NASA Astrophysics Data System (ADS)

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.

Fujita, T.; Birur, G. C.; Schredder, J. M.; Bowyer, J. M.; Awaya, H. I.

84

Comparison of advanced thermal and electrical storage for parabolic dish solar thermal power systems  

NASA Technical Reports Server (NTRS)

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.

Fujita, T.; Birur, G. C.; Schredder, J. M.; Bowyer, J. M.; Awaya, H. I.

1982-01-01

85

Secondary and compound concentrators for parabolic dish solar thermal power systems  

NASA Technical Reports Server (NTRS)

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.

Jaffe, L. D.; Poon, P. T.

1981-01-01

86

Secondary and compound concentrators for parabolic-dish solar-thermal power systems  

SciTech Connect

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.

Jaffe, L.D.; Poon, P.T.

1981-04-15

87

Software used with the flux mapper at the solar parabolic dish test site  

NASA Technical Reports Server (NTRS)

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.

Miyazono, C.

1984-01-01

88

Comparison of Fresnel lenses and parabolic mirrors as solar energy concentrators  

Microsoft Academic Search

This paper compares the gain that can be achieved with a one- or two-stage concentrator, when the first stage is a Fresnel lens or a parabolic mirror, as a function of the luminosity of the concentrator. The results show that the achievable gain using a parabolic mirror is greater than that obtained using a flat or roof lens but is

E. Lorenzo; A. Luque

1982-01-01

89

Effect of porous disc receiver configurations on performance of solar parabolic trough concentrator  

NASA Astrophysics Data System (ADS)

In this article, heat transfer enhancement of line focus solar collector with porous disc receiver is studied with water and therminol oil. A three dimensional (3-D) numerical simulation of porous disc enhanced receiver is carried out using commercial CFD software Fluent 6.3 to evolve the optimum configuration. The 3-D numerical model is solved by renormalization-group based k-? turbulent model associated with standard wall function. The effect of porous disc receiver configurations (solid disc at bottom; porous disc at bottom; porous disc at top; and alternative porous disc) on performance of the trough concentrator is investigated. The effect of porous disc geometric parameters (?, ?, W, H and t) and fluid parameters (Pr and m) on heat transfer enhancement of the receiver is also studied. The numerical simulation results show that the flow pattern around the solid and porous discs are entirely different and it significantly influences the local heat transfer coefficient. The porous disc receiver experiences low pressure drop as compared to that of solid disc receiver due to less obstruction. The optimum configuration of porous disc receiver enhances the heat transfer rate of 221 W m-1 and 13.5% with pumping penalty of 0.014 W m-1 for water and for therminol oil-55, heat transfer rate enhances of 575 W m-1 and 31.4% with pumping penalty of 0.074 W m-1 as compared to that of tubular receiver at the mass flow rate of 0.5 kg s-1. The Nusselt number and friction factor correlations are proposed for porous disc receiver to calculate heat transfer characteristics. The porous disc receiver can be used to increase the performance of solar parabolic trough concentrator.

Ravi Kumar, K.; Reddy, K. S.

2012-03-01

90

"Diffusion of Innovation: Solar Oven Use in Lesotho (Africa)." Grundy, William and Roy Grundy. Advances in Solar Cooking: Proceedings of the 2nd International Conference on Solar Cooker Use and Technology. Shyam S. Nandwani, ed. July 12-15, 1994.  

E-print Network

"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 analysis of key ideas from Eberhard's study concerning the diffusion of innovation and practices for solar

Noble, William Stafford

91

Development of Molten-Salt Heat Transfer Fluid Technology for Parabolic Trough Solar Power Plants - Public Final Technical Report  

SciTech Connect

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 projects 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.

Grogan, Dylan C. P.

2013-08-15

92

3X compound parabolic concentrating (CPC) solar energy collector. Final technical report  

SciTech Connect

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.

Ballheim, R.W.

1980-04-25

93

7 CFR 58.709 - Cookers.  

Code of Federal Regulations, 2012 CFR

...shall be equipped with a 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 valves on...

2012-01-01

94

7 CFR 58.709 - Cookers.  

Code of Federal Regulations, 2011 CFR

...shall be equipped with a 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 valves on...

2011-01-01

95

7 CFR 58.709 - Cookers.  

Code of Federal Regulations, 2013 CFR

...shall be equipped with a 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 valves on...

2013-01-01

96

The design of a parabolic reflector system with high tracking tolerance for high solar concentration  

NASA Astrophysics Data System (ADS)

A compact high concentrating photovoltaic (HCPV) module based on cassegrain optics is proposed; consisting of a primary parabolic reflector, secondary reflector and homogeniser. The effect of parabolic curvatures, reflector separation distance and the homogeniser's height and width on the tracking tolerance has been investigated for optimisation. In this type of HCPV, the addition of a solid transparent homogeniser to the two stage reflector design greatly improves the tracking tolerance. Optical simulation studies show high optical efficiencies of 84.82 - 81.89 % over a range of 1 degree tracking error and 55.49% at a tracking error of 1.5 degrees.

Shanks, Katie; Sarmah, Nabin; Reddy, K. S.; Mallick, Tapas

2014-09-01

97

The small community solar thermal power experiment. Parabolic dish technology for industrial process heat application  

Microsoft Academic Search

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

R. E. Polzien; D. Rodriguez

1981-01-01

98

Small community solar thermal power experiment. Parabolic dish technology for industrial process heat application. Final report  

Microsoft Academic Search

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

R. E. Polzien; D. Rodriguez

1981-01-01

99

Experimental investigation of parabolic-cylinder solar concentration with tubular heat receiver  

Microsoft Academic Search

The performance and characteristics of an electroplated anodized aluminum parabolic concentrator with a tubular heat receiver are described. A 2-sq-m sheet of aluminum was elastically deformed into a concentrator with a 400-mm focal length; the heat receiver was a blackened metal tube enclosed in a fluorescent light tube. Focusing errors were determined by use of a collimated light beam shone

M. A. Markman; N. V. Kolomoets; L. M. Simanovskii; Iu. I. Shmatok; O. P. Zakharova

1980-01-01

100

Design and fabrication of a low-specific-weight parabolic dish solar concentrator  

NASA Technical Reports Server (NTRS)

A segmented design and fabrication and assembly techniques were developed for a 1.8 m (6 ft) diameter parabolic concentrator for space application. This design and these techniques were adaptable to a low cost, mass-produced concentrator. Minimal machining was required. Concentrator segments of formed magnesium were used. The concentrator weighed only 1.6 kg sq m (0.32 lbm/sq ft).

Richter, C. W.; Birchenough, A. G.; Marquis, G. A.; Mroz, T. S.

1978-01-01

101

3X compound parabolic concentrating (CPC) solar energy collector. Final technical report  

Microsoft Academic Search

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

Ballheim

1980-01-01

102

Design options for low cost thermal transport piping networks for point focusing parabolic dish solar thermal systems  

SciTech Connect

Design options are investigated for low-cost thermal transport piping networks that are used to supply heat generated by parabolic dish solar thermal systems to a wide range of thermal applications. These options include (1) working fluids of steam, Therminol, and draw salt; (2) packing factors (reflecting the spacing of dishes) which range from 0.3 to 0.5; and (3) supply and return temperatures covering a range from 38/sup 0/C (100/sup 0/F) to 510/sup 0/C (950/sup 0/F). In addition, design variations involving the incorporation of flexible hoses to reduce piping network installation costs are investigated, and transient heat soak losses associated with cloud passage and evening shutdown are evaluated.

Fujita, T.; Revere, W.; Biddle, J.; Awaya, H.; DeFranco, D.

1981-01-01

103

Conceptual design of a self-deployable, high performance parabolic concentrator for advanced solar-dynamic power systems  

NASA Technical Reports Server (NTRS)

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.

Dehne, Hans J.

1991-01-01

104

Design and analysis of hydraulically driven actuation system For a parabolic solar trough  

E-print Network

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 ...

Popovi?, Katarina, S.B. Massachusetts Institute of Technology

2013-01-01

105

Mechanical development of an actuation system for a parabolic solar trough collector  

E-print Network

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 ...

Carrillo, Juan Felipe (Carrillo Salazar)

2013-01-01

106

Engineering, Financial and Net Energy Performance, and Risk Analysis for Parabolic Trough Solar Power Plants  

E-print Network

concentrating solar power plant. A set of engineering performance, financial and net energy models were developed as tools to predict a plants engineering performance, cost and energy payback. The models were validated by comparing the predicted results...

Luo, Jun

2014-08-08

107

International Experience in Standards and Labeling Programs for Rice Cookers  

SciTech Connect

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

Zhou, Nan; Zheng, Nina

2008-05-01

108

Nexant Parabolic Trough Solar Power Plant Systems Analysis; Task 1: Preferred Plant Size, 20 January 2005 - 31 December 2005  

SciTech Connect

The Rankine cycles for commercial parabolic trough solar projects range in capacity from 13.5 MWe at the Solar Electric Generating Station I (SEGS I) plant, to a maximum of 89 MWe at the SEGS VIII/IX plants. The series of SEGS projects showed a consistent reduction in the levelized energy cost due to a combination of improvements in collector field technology and economies of scale in both the Rankine cycle and the operation and maintenance costs. Nonetheless, the question of the optimum Rankine cycle capacity remains an open issue. The capacities of the SEGS VIII/IX plants were limited by Federal Energy Regulatory Commission and Public Utility Regulatory Policy Act requirements to a maximum net output of 80 MWe. Further improvements in the Rankine cycle efficiency, and economies of scale in both the capital and the operating cost, should be available at larger plant sizes. An analysis was conducted to determine the effect of Rankine cycle capacities greater than 80 MWe on the levelized energy cost. The study was conducted through the following steps: (1) Three gross cycle capacities of 88 MWe, 165 MWe, and 220 MWe were selected. (2) Three Rankine cycle models were developed using the GateCycle program. The models were based on single reheat turbine cycles, with main steam conditions of 1,450 lb{sub f}/in{sup 2} and 703 F, and reheat steam conditions of 239 lb{sub f}/in{sup 2} and 703 F. The feedwater heater system consisted of 5 closed heaters and 1 open deaerating heater. The design condenser pressure was 2.5 in. HgA. (3) The optimization function within Excelergy was used to determine the preferred solar multiple for each plant. Two cases were considered for each plant: (a) a solar-only project without thermal storage, and (b) a solar-fossil hybrid project, with 3 hours of thermal storage and a heat transport fluid heater fired by natural gas. (4) For each of the 6 cases, collector field geometries, heat transport fluid pressure losses, and heat transport pump power requirements were calculated with a field piping optimization model. (5) Annual electric energy outputs, capital costs, and annual operating costs were calculated for each case using the default methods within Excelergy, from which estimates of the levelized energy costs were developed. The plant with the lowest energy cost was considered the optimum.

Kelly, B.

2006-07-01

109

Commercialization of parabolic dish systems  

NASA Technical Reports Server (NTRS)

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.

Washom, B.

1982-01-01

110

Compound parabolic concentrators for solar-thermal power. Semiannual progress report, January--June 1975  

Microsoft Academic Search

The construction and testing of a tenfold concentrator was accomplished, and the optical and thermal performance was in excellent agreement with the mathematical model of the collector. The angular acceptance of the unit was measured by measuring the thermal output as a function of solar elevation. The results indicated that small imperfections in the shape of the collector did not

R. M. Giugler; A. Rabl; K. Reed; V. J. Sevcik; R. Winston

1975-01-01

111

Life Cycle Assessment of a Parabolic Trough Concentrating Solar Power Plant and Impacts of Key Design Alternatives: Preprint  

SciTech Connect

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.

Heath, G. A.; Burkhardt, J. J.; Turchi, C. S.

2011-09-01

112

Design and test of non-evacuated solar collectors with compound parabolic concentrators  

Microsoft Academic Search

The intermediate range of concentration ratios (1.5X-10X) which can be achieved with CPC's without diurnal tracking provides both economic and thermal advantages for solar collector design even when used with nonevacuated absorbers. The present paper summarizes more than 3 years of research on nonevacuated CPC's and reviews measured performance data and critical design considerations. Concentrations in the upper portions of

A. Rabl; J. Ogallagher; R. Winston

1979-01-01

113

Effect of porous disc receiver configurations on performance of solar parabolic trough concentrator  

Microsoft Academic Search

In this article, heat transfer enhancement of line focus solar collector with porous disc receiver is studied with water and therminol oil. A three dimensional (3-D) numerical simulation of porous disc enhanced receiver is carried out using commercial CFD software Fluent 6.3 to evolve the optimum configuration. The 3-D numerical model is solved by renormalization-group based k-? turbulent model associated

K. Ravi Kumar; K. S. Reddy

2011-01-01

114

Comparison of advanced engines for parabolic dish solar thermal power plants  

NASA Technical Reports Server (NTRS)

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.

Fujita, T.; Bowyer, J. M.; Gajanana, B. C.

1980-01-01

115

The CAESAR project: Experimental and modeling investigations of methane reforming in a CAtalytically Enhanced Solar Absorption Receiver on a parabolic dish  

SciTech Connect

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.

Muir, J.F.; Hogan, R.E. Jr.; Skocypec, R.D. [Sandia National Labs., Albuquerque, NM (US); Buck, R. [Deutsche Forschungsanstalt fuer Luft- und Raumfahrt, Stuttgart (DE). Inst. of Technical Thermodynamics

1993-07-01

116

A Nomographic Methodology for Use in Performance Trade-Off Studies of Parabolic Dish Solar Power Modules  

NASA Technical Reports Server (NTRS)

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.

Selcuk, M. K.; Fujita, T.

1984-01-01

117

Solar photoelectro-Fenton degradation of paracetamol using a flow plant with a Pt\\/air-diffusion cell coupled with a compound parabolic collector: Process optimization by response surface methodology  

Microsoft Academic Search

The degradation of 10L of 157mgL?1 paracetamol solutions in 0.05M Na2SO4 has been studied by the solar photoelectro-Fenton (SPEF) method. A solar flow plant with a Pt\\/air-diffusion electrochemical cell and a compound parabolic collector (CPC) photoreactor was used operating under recirculation mode at a liquid flow of 180Lh?1 with an average UV irradiation intensity of about 32Wm?2. A central composite

Lucio Cesar Almeida; Sergi Garcia-Segura; Nerilso Bocchi; Enric Brillas

2011-01-01

118

A review of test results on parabolic dish solar thermal power modules with dish-mounted Rankine engines and for production of process steam  

NASA Technical Reports Server (NTRS)

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.

Jaffe, Leonard D.

1988-01-01

119

The pressure cooker technique for the treatment of brain AVMs.  

PubMed

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

Chapot, Ren; Stracke, Paul; Velasco, Agla; Nordmeyer, Hannes; Heddier, Markus; Stauder, Michael; Schooss, Petra; Mosimann, Pascal J

2014-03-01

120

Optimum Construction of Heating Coil for Domestic Induction Cooker  

NASA Astrophysics Data System (ADS)

The design and optimization of the parameters of heating coil is very important for the analytical analysis of high frequency inverter fed induction cooker. Moreover, accurate prediction of high frequency winding loss (i.e., losses due to skin and proximity effects) is necessary as the induction cooker used in power electronics applications. At high frequency current penetration in the induction coil circuit is very difficult for conducting wire due to skin-effect. To eradicate the skin effect heating coil is made up of bundle conductor i.e., litz wire. In this paper inductances and AC resistances of a litz-wire are calculated and optimized by considering the input parameters like wire type, shape, number of strand, number of spiral turn, number of twist per feet of heating coil and operating frequency. A high frequency half bridge series resonant mirror inverter circuit is used in this paper and taking the optimum values of inductance and ac resistance the circuit is simulated through PSPICE simulations. It has been noticed that the results are feasible enough for real implementation.

Sinha, Dola; Bandyopadhyay, Atanu; Sadhu, Pradip Kumar; Pal, Nitai

2010-10-01

121

Degradation of pharmaceutical beta-blockers by electrochemical advanced oxidation processes using a flow plant with a solar compound parabolic collector.  

PubMed

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? 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?. However, the Pt/ADE-Pt/CF cell gave much lower energy consumptions of about 0.080 kWh g TOC? 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

Isarain-Chvez, Eloy; Rodrguez, Rosa Mara; Cabot, Pere Llus; Centellas, Francesc; Arias, Conchita; Garrido, Jos Antonio; Brillas, Enric

2011-08-01

122

Solar reforming of methane in a direct absorption catalytic reactor on a parabolic dish: II-modeling and analysis  

SciTech Connect

The CAtalytically Enhanced Solar Absorption Receiver (CAESAR) test was conducted to determine the thermal, chemical, and mechanical performance of a commercial-scale, dish-mounted, direct catalytic absorption receiver (DCAR) reactor over a range of steady state and transient (cloud) operating conditions. The focus of the test was to demonstrate [open quotes]proof-of-concept[close quotes] and determine global performance such as reactor efficiencies and overall methane conversion. A numerical model was previously developed to provide guidance in the design of the absorber. The one-dimensional, planar, and steady-state model incorporates the following energy transfer mechanisms: solar and infrared radiation, heterogeneous chemical reaction, conduction in the solid phase, and convection between the fluid and solid phases. Improvements to the model and improved property values are presented here. In particular, the solar radiative transfer model is improved by using a three-flux technique to more accurately represent the typically conical incident flux. A spatially varying catalyst loading is incorporated, convective and radiative properties for each layer in the multilayer absorber are determined, and more realistic boundary conditions are applied. Considering that this test was not intended to provide data for code validation, model predictions are shown to generally bound the test axial thermocouple data when test uncertainties are included. Global predictions are made using a technique in which the incident solar flux distribution is subdivided into flux contour bands. Reactor predictions for anticipated operating conditions suggest that a further decrease in optical density (i.e., extinction coefficient) at the front of the absorber inner disk may improve absorber conditions. Code-validation experiments are needed to improve the confidence in the simulation of large-scale reactor operation.

Skocypec, R.D.; Hogan, R.E. Jr.; Muir, J.F. (Sandia National Labs., Albuquerque, NM (United States))

1994-06-01

123

Solar Week Thursday: Shoebox Solar Water Heater  

NSDL National Science Digital Library

This is an activity during Solar Week, a twice-yearly event in March and October during which classrooms are able to interact with scientists studying the Sun. Outside of Solar Week, information, activities, and resources are archived and available online at any time. This is an activity about reflection. In this hands-on activity, learners will build a solar water heater by lining a box with reflective material, adding a translucent cover, and adding water-filled cans that are painted black. The temperature of the water is taken and recorded every fifteen minutes. This activity can use the same solar cooker built for the Solar Week Thursday: Solar Pizza Box Cooker activity. This activity is scheduled to occur during Thursday of Solar Week, and it requires use of a sunny outdoor location for an extended period of time.

124

Cooking Amount Estimation of Rice Cooker by Signed Mahalanobis Distance  

NASA Astrophysics Data System (ADS)

This paper proposes a cooking amount estimation method for rice cookers based on Mahalanobis-Taguchi system. This estimation is important in that it can improve the cooking quality significantly. The proposed method enables us to estimate the amount in the early stage of cooking, thereby to give optimal heat in the whole process. To this end, an existing method adopts the minimal cooking quantity as a standard quantity and conduct estimation via outliers in terms of Mahalanobis distance, but this is easily affected by consumers' usage and nonlinearity peculiar to heat systems. Estimation precision is expected to be higher if the estimation is used by correlation of each characteristic data. The proposed method achieves this by adding sign to the estimation method for treating negative values in Mahalanobis distance, and verifies its effectiveness by experiments.

Suzuki, Arata; Sugimoto, Kenji

125

Optimal Heat Collection Element Shapes for Parabolic Trough Concentrators  

SciTech Connect

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.

Bennett, C

2007-11-15

126

The French thermo-helio-electricity-KW parabolic dish program  

NASA Technical Reports Server (NTRS)

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.

Audibert, M.; Peri, G.

1982-01-01

127

Parabolic - hyperbolic boundary layer  

E-print Network

A boundary value problem related to a parabolic higher order operator with a small parameter is analized. When the small parameter tends to zero, the reduced operator is hyperbolic. When t tends to infinity a parabolic hyperbolic boundary layer appears. In this paper a rigorous asymptotic approximation uniformly valid for all t is established.

Monica De Angelis

2012-07-09

128

Parabolic dish test site: History and operating experience  

NASA Technical Reports Server (NTRS)

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.

Selcuk, M. K. (compiler)

1985-01-01

129

Understanding the Clausius-Clapeyron Equation by Employing an Easily Adaptable Pressure Cooker  

ERIC Educational Resources Information Center

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

Galleano, Monica; Boveris, Alberto; Puntarulo, Susana

2008-01-01

130

Parabolic Trough Organic Rankine Cycle Power Plant  

SciTech Connect

Arizona Public Service (APS) is required to generate a portion of its electricity from solar resources in order to satisfy its obligation under the Arizona Environmental Portfolio Standard (EPS). In recent years, APS has installed and operates over 4.5 MWe of fixed, tracking, and concentrating photovoltaic systems to help meet the solar portion of this obligation and to develop an understanding of which solar technologies provide the best cost and performance to meet utility needs. During FY04, APS began construction of a 1-MWe parabolic trough concentrating solar power plant. This plant represents the first parabolic trough plant to begin construction since 1991. The plant will also be the first commercial deployment of the Solargenix parabolic trough collector technology developed under contract to the National Renewable Energy Laboratory (NREL). The plant will use an organic Rankine cycle (ORC) power plant, provided by Ormat. The ORC power plant is much simpler than a conventional steam Rankine cycle power plant and allows unattended operation of the facility.

Canada, S.; Cohen, G.; Cable, R.; Brosseau, D.; Price, H.

2005-01-01

131

Optical and thermal properties of Compound Parabolic Concentrators  

Microsoft Academic Search

Compound Parabolic Concentrators (CPC) are relevant for solar energy collection because they achieve the highest possible concentration for any acceptance angle (tracking requirement). The convective and radiative heat transfers through a CPC are calculated, and formulas for evaluating the performance of solar collectors based on the CPC principle are presented. A simple analytic technique for calculating the average number of

A. Rabl

1976-01-01

132

Optimization of the tubular absorber using a compound parabolic concentrator  

Microsoft Academic Search

The paper deals with the optimization of the tubular absorber of a compound parabolic concentrator (CPC) solar collector. In order to minimize the radiation thermal losses from the absorber, a modified absorber with multi-cavities is proposed. The cavities are introduced at the circumferential area with relatively high solar intensities. These areas were determined by the use of a ray-tracing technique.

H. E. I. Khonkar; A. A. M. Sayigh

1995-01-01

133

Solar Energy Education. Home economics: student activities. Field test edition  

SciTech Connect

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)

Not Available

1981-03-01

134

Parabolically connected subgroups  

SciTech Connect

All reductive spherical subgroups of the group SL(n) are found for which the intersections with every parabolic subgroup of SL(n) are connected. This condition guarantees that open equivariant embeddings of the corresponding homogeneous spaces into Moishezon spaces are algebraic. Bibliography: 6 titles.

Netai, Igor V [M. V. Lomonosov Moscow State University, Faculty of Mechanics and Mathematics, Moscow (Russian Federation)

2011-08-31

135

The use of solar energy for cooking in developing countries  

Microsoft Academic Search

Solar cooking has received considerable attention recently as an alternative to cooking with woodfuel. This paper determines the effective solar collection area required, and examines the different design features to optimize the available heat from a small collection area. A quasi-parabola was developed and tested alongside two other prototypes. The locally-made cooker was preferred by Sudanese women for its speed

LESLEY V. BRATTLE; ROGER J. IRVING

1986-01-01

136

Changes in the contents and profiles of selected phenolics, soyasapogenols, tocopherols, and amino acids during soybean-rice mixture cooking: Electric rice cooker vs electric pressure rice cooker.  

PubMed

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

Kim, Seung-Hyun; Yu, Bo-Ra; Chung, Ill-Min

2015-06-01

137

Parabolic torus transreflector antenna  

NASA Astrophysics Data System (ADS)

The possible scan rate of conventional radar antennas using parabolic dishes is limited to about 60 rev/min. This limitation is related to mechanical rotation requirements. Many radar applications require high data renewal rates, including short-range defense systems and systems for reduction of sea clutter. Faster scan rates can be obtained by using phased arrays and electronic scanning. However, the use of the required equipment introduces considerable complexity and cost. The present investigation is concerned with a novel form of antenna permitting high scan rates, taking into account a parabolic torus transreflector antenna. The feed horn illuminates one side of the radome with polarization parallel to the wires, which therefore reflect the radiation like a dish antenna. In the antenna considered, rotation of the beam is effected by mechanical rotation of the horn feed only, and this provides the potential for high scanning rates.

Diaz, L. M.; Smith, M. S.

1984-12-01

138

On Parabolic Whittaker Functions  

NASA Astrophysics Data System (ADS)

We propose the Mellin-Barnes integral representation for a solution to generalized (parabolic) quantum Toda lattice, which presumably describes the S 1 U N -equivariant Gromov-Witten invariants of the Grassmann variety. Our construction is built on a generalization of the standard Whittaker model for principal series {{U}({gl}_N)}-modules, and its special realization by difference operators. Particularly, our result provides a representation theoretic derivation of the conjectural formula due to Hori and Vafa.

Oblezin, Sergey

2012-09-01

139

Flux Distribution of a Single-Axis Tracking Parabolic Trough Array with Photovoltaic Receiver  

E-print Network

. With single-axis tracking the incident solar rays are not in general perpendicular to the trough. NonFlux Distribution of a Single-Axis Tracking Parabolic Trough Array with Photovoltaic Receiver G 0200 Australia E-mail: gregory.burgess@anu.edu.au Abstract Single-axis tracking parabolic troughs

140

Status of APS 1-Mwe Parabolic Trough Project  

SciTech Connect

Arizona Public Service (APS) is currently installing new power facilities to generate a portion of its electricity from solar resources that will satisfy its obligation under the Arizona Environmental Portfolio Standard (EPS). During FY04, APS began construction on a 1-MWe parabolic trough concentrating solar power plant. This plant represents the first parabolic trough plant to begin construction since 1991. Site preparation and construction activities continued throughout much of FY05, and startup activities are planned for Fall 2005 (with completion early in FY06). The plant will be the first commercial deployment of the Solargenix parabolic trough collector technology developed under contract to the National Renewable Energy Laboratory. The plant will use an organic Rankine cycle (ORC) power plant, provided by Ormat. The ORC power plant is much simpler than the conventional steam Rankine cycle plant and allows unattended operation of the facility.

Canada, S.; Brosseau, D.; Kolb, G.; Moore, L.; Cable, R.; Price, H.

2005-11-01

141

Two dimensional compound parabolic concentrating collectors. Final report  

Microsoft Academic Search

Seven different compound parabolic concentrating (CPC) collector designs were tested by the ray trace method. The comparison of the collector was performed by simulating sunlight striking the designs at various angles of the sun during the course of the day. All of the CPC solar collector designs used the same type of reflective material, Kinglux reflective aluminum, which is a

J. P. Henry; N. T. Gamble; S. A. Cassidy

1983-01-01

142

Collector with cusplike compound parabolic concentrator and selective absorber  

Microsoft Academic Search

A nonevacuated solar collector with a cusplike compound parabolic concentrator (CPC) and tubular absorber has been built. Since the reflector surrounds the absorber on all sides, little insulating material is needed. Furthermore, the quantity of absorber material relative to unit collector aperture is smaller than in any other collector of comparable acceptance angle. This feature optimizes both transient response and

A. Rabl

1976-01-01

143

Analysis and design of two stretched-membrane parabolic dish concentrators  

Microsoft Academic Search

The state-of-the-art of parabolic dish solar concentrators is the faceted, glass-metal dish. The mass production costs of glass-metal dishes may be high because they do not incorporate the innovations of design and materials developed over the last eight years. Therefore, Sandia National Laboratories has undertaken to develop two stretched-membrane parabolic dish concentrators for the Department of Energy's Solar Thermal Program.

Thomas R. Mancini

1991-01-01

144

Parabolic aircraft solidification experiments  

NASA Technical Reports Server (NTRS)

A number of solidification experiments have been utilized throughout the Materials Processing in Space Program to provide an experimental environment which minimizes variables in solidification experiments. Two techniques of interest are directional solidification and isothermal casting. Because of the wide-spread use of these experimental techniques in space-based research, several MSAD experiments have been manifested for space flight. In addition to the microstructural analysis for interpretation of the experimental results from previous work with parabolic flights, it has become apparent that a better understanding of the phenomena occurring during solidification can be better understood if direct visualization of the solidification interface were possible. Our university has performed in several experimental studies such as this in recent years. The most recent was in visualizing the effect of convective flow phenomena on the KC-135 and prior to that were several successive contracts to perform directional solidification and isothermal casting experiments on the KC-135. Included in this work was the modification and utilization of the Convective Flow Analyzer (CFA), the Aircraft Isothermal Casting Furnace (ICF), and the Three-Zone Directional Solidification Furnace. These studies have contributed heavily to the mission of the Microgravity Science and Applications' Materials Science Program.

Workman, Gary L. (Principal Investigator); Smith, Guy A.; OBrien, Susan

1996-01-01

145

Non-Formal Environmental Education: The Utilization of Solar Energy for Cooking in a Rural Area in Sudan.  

ERIC Educational Resources Information Center

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)

El Zubeir, Z.

1997-01-01

146

Parabolized stability equations  

NASA Technical Reports Server (NTRS)

The parabolized stability equations (PSE) are a new approach to analyze the streamwise evolution of single or interacting Fourier modes in weakly nonparallel flows such as boundary layers. The concept rests on the decomposition of every mode into a slowly varying amplitude function and a wave function with slowly varying wave number. The neglect of the small second derivatives of the slowly varying functions with respect to the streamwise variable leads to an initial boundary-value problem that can be solved by numerical marching procedures. The PSE approach is valid in convectively unstable flows. The equations for a single mode are closely related to those of the traditional eigenvalue problems for linear stability analysis. However, the PSE approach does not exploit the homogeneity of the problem and, therefore, can be utilized to analyze forced modes and the nonlinear growth and interaction of an initial disturbance field. In contrast to the traditional patching of local solutions, the PSE provide the spatial evolution of modes with proper account for their history. The PSE approach allows studies of secondary instabilities without the constraints of the Floquet analysis and reproduces the established experimental, theoretical, and computational benchmark results on transition up to the breakdown stage. The method matches or exceeds the demonstrated capabilities of current spatial Navier-Stokes solvers at a small fraction of their computational cost. Recent applications include studies on localized or distributed receptivity and prediction of transition in model environments for realistic engineering problems. This report describes the basis, intricacies, and some applications of the PSE methodology.

Herbert, Thorwald

1994-01-01

147

Participation in multilateral effort to develop high performance integrated CPC evacuated collectors. [Compound Parabolic Concentrator (CPC)  

Microsoft Academic Search

The University of Chicago Solar Energy Group has had a continuing program and commitment to develop an advanced evacuated solar collector integrating nonimaging concentration into its design. During the period from 1985--1987, some of our efforts were directed toward designing and prototyping a manufacturable version of an Integrated Compound Parabolic Concentrator (ICPC) evacuated collector tube as part of an international

R. Winston; J. J. OGallagher

1992-01-01

148

Criteria for evaluation of reflective surface for parabolic dish concentrators  

NASA Technical Reports Server (NTRS)

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.

Bouquet, F.

1980-01-01

149

Composite isogrid structures for parabolic surfaces  

NASA Technical Reports Server (NTRS)

The invention relates to high stiffness parabolic structures utilizing integral reinforced grids. The parabolic structures implement the use of isogrid structures which incorporate unique and efficient orthotropic patterns for efficient stiffness and structural stability.

Silverman, Edward M. (Inventor); Boyd, Jr., William E. (Inventor); Rhodes, Marvin D. (Inventor); Dyer, Jack E. (Inventor)

2000-01-01

150

Transversal filter for parabolic phase equalization  

NASA Technical Reports Server (NTRS)

An equalizer (10) for removing parabolic phase distortion from an analog signal (3), utilizing a pair of series connected transversal filters. The parabolic phase distortion is cancelled by generating an inverse parabolic approximation using a sinusoidal phase control filter (18). The signal (3) is then passed through an amplitude control filter (21) to remove magnitude ripple components.

Kelly, Larry R. (Inventor); Waugh, Geoffrey S. (Inventor)

1993-01-01

151

Entropy burst from parabolic potentials  

Microsoft Academic Search

The change of the ground-state energy is investigated in a thermodynamical process by using the model described by one-dimensional harmonic oscillator + two-dimensional isotropic parabolic potential barrier. When two systems are suddenly mixed, the lowest energy changes through the mixing and the entropy burst occurs.

Tsunehiro Kobayashi; Toshiki Shimbori

2001-01-01

152

Parabolic tapers for overmoded waveguides  

DOEpatents

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.

Doane, J.L.

1983-11-25

153

Effects of the Sun on our Planet  

NSDL National Science Digital Library

Students experiment with plants, light, heat, and water evaporation. They experiment with solar cells to design a simple solar cooker, create a "solar-powered" method to perform a routine task, or build a parabolic solar collector. They explore radio signals during daytime and nighttime. Older students construct an ionosphere monitor to track solar storms and other changes in the ionosphere.

2013-06-12

154

Achieving uniform efficient illumination with multiple asymmetric compound parabolic luminaires  

NASA Astrophysics Data System (ADS)

Luminaire designs based on multiple asymmetric nonimaging compound parabolic reflectors are proposed for 2-D illumination applications that require highly uniform far-field illuminance, while insuring maximal lighting efficiency and sharp angular cutoffs. The new designs derive from recent advances in nonimaging secondary concentrators for line-focus solar collectors. The light source is not treated as a single entity, but rather is divided into two or more separate adjoining sources. An asymmetric Compound Parabolic Luminaire is then designed around each half-source. Attaining sharp cutoffs requires relatively large reflectors. However, severe truncation of the reflectors renders these devices as compact as many conventional luminaires, at the penalty of a small fraction of the radiation being emitted outside the nominal cutoff. The configurations that maximize the uniformity of far-field illumination offer significant improvements in flux homogeneity relative to alternative designs to date.

Gordon, Jeffrey M.; Kashin, Peter

1993-11-01

155

Microcontroller-Based TwoAxis Solar Tracking System  

Microsoft Academic Search

The main goal of this project is to develop and implement a prototype of two-axis solar tracking system based on a PIC microcontroller. The parabolic reflector or parabolic dish is constructed around two feed diameter to capture the sun's energy. The focus of the parabolic reflector is theoretically calculated down to an infinitesimally small point to get extremely high temperature.

Lwin Lwin Oo; Nang Kaythi Hlaing

2010-01-01

156

Solar photoreactors comparison based on oxalic acid photocatalytic degradation  

Microsoft Academic Search

Solar heterogeneous photocatalytic degradation of oxalic acid in water is carried out in four different solar photoreactors: a parabolic trough concentrator (PC), a tubular collector (TC), a compound parabolic collector (CPC), and a V-trough collector (VC). The reactors operate under equal conditions of solar irradiance, collection surface and fluid flow rate to ensure a better comparison between the systems. The

Erick R. Bandala; Camilo A. Arancibia-Bulnes; Sayra L. Orozco; Claudio A. Estrada

2004-01-01

157

Annular solar receiver thermal characteristics  

Microsoft Academic Search

Results from thermal studies performed for an annular solar receiver assembly to be used with the 2 m, 90 deg parabolic collector trough are presented. The receiver configuration modeled consists of a 2.54 cm o.d. steel tube with a black chrome selective surface and an enclosing concentric Pyrex glass envelope. Previous thermal work conducted on the parabolic cylindrical collector design

A. C. Ratzel; C. E. Sisson

1980-01-01

158

Optimum operating conditions for a cylindrical parabolic focusing collector\\/Rankine power generation cycle system  

Microsoft Academic Search

System operating temperatures, boiler pressure, and associated parameters which maximize solar to electric conversion efficiency and which minimize collector\\/storage\\/power cycle system costs were determined for an electrical generation system which uses cylindrical parabolic focusing collectors as a source of heat, a stratified liquid unit for storage, and a Rankine power generation cycle for electrical generation. To perform a parametric study

M. W. Edenburn

1977-01-01

159

Overview of software development at the parabolic dish test site  

NASA Technical Reports Server (NTRS)

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.

Miyazono, C. K.

1985-01-01

160

Solargenix Energy Advanced Parabolic Trough Development  

SciTech Connect

The Solargenix Advanced Trough Development Project was initiated in the Year 2000 with the support of the DOE CSP Program and, more recently, with the added support of the Nevada Southwest Energy Partnership. Parabolic trough plants are the most mature solar power technology, but no large-scale plants have been built in over a decade. Given this lengthy lull in deployment, our first Project objective was development of improved trough technology for near-term deployment, closely patterned after the best of the prior-generation troughs. The second objective is to develop further improvements in next-generation trough technology that will lead to even larger reductions in the cost of the delivered energy. To date, this Project has successfully developed an advanced trough, which is being deployed on a 1-MW plant in Arizona and will soon be deployed in a 64-MW plant in Nevada. This advanced trough offers a 10% increase in performance and over an 20% decrease in cost, relative to prior-generation troughs.

Gee, R. C.; Hale, M. J.

2005-11-01

161

Solar  

NSDL National Science Digital Library

What part does solar energy play in satisfying energy demands? This informational piece, part of a series about the future of energy, introduces students to solar energy. Here students read about the uses, benefits, and active and passive methods of solar energy. Information is also presented about limitations, geographical considerations of solar power in the United States, and current uses of solar energy around the world. Thought-provoking questions afford students chances to reflect on what they've read about the uses of solar energy. Articles and information about a solar power plant in the Mohave Desert, the use of solar energy in Iowa, and statistics about solar energy are provided in a sidebar.

Project, Iowa P.

2004-01-01

162

Parabolic curves in Lie groups  

SciTech Connect

To interpolate a sequence of points in Euclidean space, parabolic splines can be used. These are curves which are piecewise quadratic. To interpolate between points in a (semi-)Riemannian manifold, we could look for curves such that the second covariant derivative of the velocity is zero. We call such curves Jupp and Kent quadratics or JK-quadratics because they are a special case of the cubic curves advocated by Jupp and Kent. When the manifold is a Lie group with bi-invariant metric, we can relate JK-quadratics to null Lie quadratics which arise from another interpolation problem. We solve JK-quadratics in the Lie groups SO(3) and SO(1,2) and in the sphere and hyperbolic plane, by relating them to the differential equation for a quantum harmonic oscillator00.

Pauley, Michael [School of Mathematics and Statistics, University of Western Australia, 35 Stirling Highway, Crawley, Western Australia 6009 (Australia)

2010-05-15

163

Combined solar organic Rankine cycle with reverse osmosis desalination process: Energy, exergy, and cost evaluations  

Microsoft Academic Search

Organic Rankine cycles (ORC) have unique properties that are well suited to solar power generation. In this work design and performance calculations are performed using MatLab\\/SimuLink computational environment. The cycle consists of thermal solar collectors (Flat Plate Solar Collector (FPC), or Parabolic Trough Collector (PTC), or Compound Parabolic Concentrator (CPC)) for heat input, expansion turbine for work output, condenser unit

A. S. Nafey; M. A. Sharaf

2010-01-01

164

Engineering Area Investigation of Reliability Attributes and Accelerated Stress Factors on Terrestrial Solar Cells  

NASA Technical Reports Server (NTRS)

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.

Lathrop, J. W.; Prince, J. L.

1979-01-01

165

75 FR 20377 - Notice of Availability of the Draft Environmental Impact Statement for the Proposed Sonoran Solar...  

Federal Register 2010, 2011, 2012, 2013

...and 3285 Renewable Energy Development by the...parabolic trough solar thermal technology to produce...8-inch pipeline. A thermal energy storage (TES) system...the Sonoran Solar Energy Project is to respond...decommission a solar thermal facility on...

2010-04-19

166

Performance of a solar-thermal collector  

NASA Technical Reports Server (NTRS)

Possible means of achieving the technology required for field application of solar thermal power systems are discussed. Simplifications in construction techniques as well as in measurement techniques for parabolic trough collectors are described. Actual measurement data is also given.

Higa, W. H.

1975-01-01

167

Parabolic trough reflector manufactured with aluminum first surface mirrors thermally sagged  

Microsoft Academic Search

This project was conceived with the aim of developing a parabolic trough concentrator with first surface solar mirrors made over floated soda-lime glasses with concave geometry. In order to cover all the surface of the concentrator, whose measurements were 2.37m of aperture and 1.14m long, 16 mirrors were built with sizes of 0.30.6m and they were put together like a

Ivn Mart??nez; Rafael Almanza; Marcos Mazari; Genaro Correa

2000-01-01

168

Chaotic motion of comets in near-parabolic orbit: Mapping aproaches  

NASA Astrophysics Data System (ADS)

There exist many comets with near-parabolic orbits in the solar system. Among various theories proposed to explain their origin, the Oort cloud hypothesis seems to be the most reasonable. The theory assumes that there is a cometary cloud at a distance 103 to 107 from the sun and that perturbing forces from planets or stars make orbits of some of these comets become the near-parabolic type. Concerning the evolution of these orbits under planetary perturbations, we can raise the question: Will they stay in the solar system forever or will they escape from it? This is an attractive dynamical problem. If we go ahead by directly solving the dynamical differential equations, we may encounter the difficulty of long-time computation. For the orbits of these comets are near-parabolic and their periods are too long to study on their long-term evolution. With mapping approaches the difficulty will be overcome. In another aspect, the study of this model has special meaning for chaotic dynamics. We know that in the neighborhood of any separatrix i.e. the trajectory with zero frequency of the uperturbed motion of a Hamiltonian system, some chaotic motions have to be expected. Actually, the simplest example of separatrix is the parabolic trajectory of the two-body problem which separates the bounded and unbounded motion. From this point of view, the dynamical study of near-parabolic motion is very important. Petrosky's elegant but more abstract deduction gives a Kepler mapping which describes the dynamics of the cometary motion. In this paper we derive a similar mapping directly and discuss its dynamical characters.

Liu, Jie; Sun, Yi-Sui

1994-09-01

169

Controllable parabolic-cylinder optical rogue wave  

NASA Astrophysics Data System (ADS)

We demonstrate controllable parabolic-cylinder optical rogue waves in certain inhomogeneous media. An analytical rogue wave solution of the generalized nonlinear Schrdinger equation with spatially modulated coefficients and an external potential in the form of modulated quadratic potential is obtained by the similarity transformation. Numerical simulations are performed for comparison with the analytical solutions and to confirm the stability of the rogue wave solution obtained. These optical rogue waves are built by the products of parabolic-cylinder functions and the basic rogue wave solution of the standard nonlinear Schrdinger equation. Such rogue waves may appear in different forms, as the hump and paw profiles.

Zhong, Wei-Ping; Chen, Lang; Beli?, Milivoj; Petrovi?, Nikola

2014-10-01

170

Controllable parabolic-cylinder optical rogue wave.  

PubMed

We demonstrate controllable parabolic-cylinder optical rogue waves in certain inhomogeneous media. An analytical rogue wave solution of the generalized nonlinear Schrdinger equation with spatially modulated coefficients and an external potential in the form of modulated quadratic potential is obtained by the similarity transformation. Numerical simulations are performed for comparison with the analytical solutions and to confirm the stability of the rogue wave solution obtained. These optical rogue waves are built by the products of parabolic-cylinder functions and the basic rogue wave solution of the standard nonlinear Schrdinger equation. Such rogue waves may appear in different forms, as the hump and paw profiles. PMID:25375612

Zhong, Wei-Ping; Chen, Lang; Beli?, Milivoj; Petrovi?, Nikola

2014-10-01

171

Multiscale numerical methods for some types of parabolic equations  

E-print Network

In this dissertation we study multiscale numerical methods for nonlinear parabolic equations, turbulent diffusion problems, and high contrast parabolic equations. We focus on designing and analysis of multiscale methods which can capture the effects...

Nam, Dukjin

2009-05-15

172

Computer simulation for the concentration distribution of the parabolic cylinder and paraboloid concentrators  

SciTech Connect

A computer simulation for the solar concentration distributions for parabolic cylinder and paraboloid concentrators was developed. The method represented in this work deals with the solar rays on an individual basis which is considered as an analogy to a microscopic approach to the concentration problem. The concept of concentration is related to the distribution of the solar rays, photon, at the focal planes of the concentrators. A mathematical model was developed to simulate the concentration process of the solar rays with its three main patterns: the falling solar rays and their distribution across the solar disk, the reflection of the rays over the concentrator surface, and the reception of the concentrated rays at the concentrator focal plane. A three-dimensional ray trace analysis was used with the resulting sets of vectors equations solved by the computer. Several checks for the method developed with the available results are also given. An analysis was performed for the concentration distributions of the parabolic cylinder concentrators for the perfect shaded and unshaded conditions. For the paraboloid concentrators, the case of perfect concentration under a non-uniform sun was treated. Also a full analysis of the off-focus concentration was made.

El-Haggan, A.M.

1984-01-01

173

Solar concentrator development in the United States  

Microsoft Academic Search

Sandia National Laboratories leads the US Department of Energy's solar concentrator development program in a joint effort with the Solar Energy Research Institute. The goal of DOE's program is to develop, build and test solar concentrations that are low is cost, have high performance, and long lifetimes. Efforts are currently focused on three areas: low-cost heliostats, point-focus parabolic dishes, and

Daniel J. Alpert; Thomas R. Mancini; Richard M. Houser; James W. Grossman; Paul Schissel; Meir Carasso; Gary Jorgensen; Martin Scheve

1991-01-01

174

Solar-pumped solid-state lasers  

Microsoft Academic Search

Results are presented for direct solar pumping of a Nd:YAG rod laser. Stable CW output of more than 60 W was obtained with a slope efficiency exceeding 2 percent. A compound parabolic concentrator, designed to increase the solar radiation coupled into the laser rod, was used in these experiments. The results are consistent with predictions based on a single solar-pumped

M. Weksler; J. Shwartz

1988-01-01

175

A STRONGLY DEGENERATE PARABOLIC AGGREGATION EQUATION  

E-print Network

A STRONGLY DEGENERATE PARABOLIC AGGREGATION EQUATION F. BETANCOURTA, R. B¨URGERB, AND K. H. KARLSENC Abstract. This paper is concerned with a strongly degenerate convection- diffusion equation in one of the given position. This equation can be understood as a model of aggregation of the individuals

176

Operator methods of the parabolic potential barrier  

Microsoft Academic Search

The one-dimensional parabolic potential barrier dealt with in an earlier paper [T. Shimbori, T. Kobayashi, Nuovo Com B 115 (2000) 325] is re-examined from the point of view of operator methods, for the purpose of getting generalized Fock spaces.

Toshiki Shimbori

2000-01-01

177

Operator methods of the parabolic potential barrier  

NASA Astrophysics Data System (ADS)

The one-dimensional parabolic potential barrier dealt with in an earlier paper [T. Shimbori, T. Kobayashi, Nuovo Com B 115 (2000) 325] is re-examined from the point of view of operator methods, for the purpose of getting generalized Fock spaces.

Shimbori, Toshiki

2000-08-01

178

Discontinuous Mixed Covolume Methods for Parabolic Problems  

PubMed Central

We present the semidiscrete and the backward Euler fully discrete discontinuous mixed covolume schemes for parabolic problems on triangular meshes. We give the error analysis of the discontinuous mixed covolume schemes and obtain optimal order error estimates in discontinuous H(div) and first-order error estimate in L2. PMID:24983008

Zhu, Ailing

2014-01-01

179

Riesz Potentials and Nonlinear Parabolic Equations  

NASA Astrophysics Data System (ADS)

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.

Kuusi, Tuomo; Mingione, Giuseppe

2014-06-01

180

Manufacture of large, lightweight parabolic antennas  

NASA Technical Reports Server (NTRS)

Antenna was produced in segments. Parabole sections were built up as aluminum foil sandwich with core bonded by film adhesive; whole structure was oven-cured after assembly. Structure was assembled with special tool for splice-bonding segments into complete dish, and inflatable bladder to apply pressure at joints during cure.

Hooper, S. W.

1973-01-01

181

Parabolic SPDEs driven by Poisson white noise  

Microsoft Academic Search

Stochastic partial differential equations (SPDEs) of parabolic type driven by (pure) Poisson white noise are investigated in this paper. These equations are interpreted as stochastic integral equations of the jump type involving evolution kernels. Existence and uniqueness of the solution is established.

Sergio Albeverio; Jiang-Lun Wu; Tu-Sheng Zhang

1998-01-01

182

Prolonging Microgravity on Parabolic Airplane Flights  

NASA Technical Reports Server (NTRS)

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.

Robinson, David W.

2003-01-01

183

Nanofocusing Parabolic Refractive X-Ray Lenses  

SciTech Connect

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.

Schroer, C.G.; Kuhlmann, M.; Hunger, U.T.; Guenzler, T.F.; Kurapova, O.; Feste, S.; Lengeler, B. [II. Physikalisches Institut, Aachen University, D-52056 Aachen (Germany); Drakopoulos, M.; Somogyi, A.; Simionovici, A. S.; Snigirev, A.; Snigireva, I. [European Synchrotron Radiation Facility ESRF, BP 220, F-38043 Grenoble (France)

2004-05-12

184

Near-term improvements in parabolic troughs: an economic and performance assessment  

SciTech Connect

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.

Gee, R.; Murphy, L.M.

1981-08-01

185

Large-scale synthesis of well-dispersed copper nanowires in an electric pressure cooker and their application in transparent and conductive networks.  

PubMed

We present a novel large-scale synthetic method for well-separated copper nanowires (CuNWs) in a commercial electric pressure cooker under mild reaction conditions. CuNWs (?2.1 g) can be prepared in a batch with the cost of $4.20/g. Well-dispersed polyvinylpyrrolidone-capped CuNWs were obtained via a ligand-exchange method. The transparent and conductive CuNW networks with excellent electrical conductivity and high optical transmittance (30 ?/? at 86% transmittance, respectively) were fabricated by a spin-coating process. PMID:24750021

Li, Shenjie; Chen, Yanyan; Huang, Lijian; Pan, Daocheng

2014-05-01

186

The parabolic concentrating collector: A tutorial  

NASA Technical Reports Server (NTRS)

A tutorial overview of point-focusing parabolic collectors is presented. Optical and thermal characteristics are discussed. Data representing typical achievable collector efficiencies are presented and the importance of balancing collector cost with concentrator quality is argued through the development of a figure of merit. Various types of two-axis tracking collectors are described. The Department of Energy program to develop these devices is briefly discussed, as are present and projected costs for these collectors.

Truscello, V. C.

1979-01-01

187

Solar energy modulator  

NASA Technical Reports Server (NTRS)

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.

Hale, R. R. (inventor); Mcdougal, A. R.

1984-01-01

188

Bifurcation and stability for a nonlinear parabolic partial differential equation  

NASA Technical Reports Server (NTRS)

Theorems are developed to support bifurcation and stability of nonlinear parabolic partial differential equations in the solution of the asymptotic behavior of functions with certain specified properties.

Chafee, N.

1973-01-01

189

Energy 101: Concentrating Solar Power  

ScienceCinema

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.

None

2013-05-29

190

Stationary type solar energy collector apparatus  

Microsoft Academic Search

A hybrid collector for collecting solar energy is disclosed comprised of a plurality of parabolic reflectors cooperating with tube\\/fin type fluid carrying collector elements, selective ones of which are arranged at the focal points of the parabolas. Additional tube\\/fin elements are positioned at a spaced distance above the boundary line between adjacent parabolic reflectors. The exterior surfaces of the tube\\/fin

1979-01-01

191

Solar aqua-ammonia absorption refrigerator simulation  

Microsoft Academic Search

Thermodynamic analysis of an Ammonia-water absorption refrigeration cycle performance, using solar energy in the generator, is simulated by means of a PC program. The economic feasibility of the system for ice production is studied in two southern locations of Spain. For the solar energy collection unit, a Compound Parabolic Collector (CPC) is considered. The optimal value of the Coefficient of

E. Elegido; J. M. De Juana; M. A. Herrero

1991-01-01

192

The potential economic benefit of using parabolic trough collectors to supplement power cycle boilers  

NASA Astrophysics Data System (ADS)

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.

Schimmel, W. P., Jr.; Lukens, L. L.

1981-11-01

193

Parabolic Refined Invariants and Macdonald Polynomials  

NASA Astrophysics Data System (ADS)

A string theoretic derivation is given for the conjecture of Hausel, Letellier and Rodriguez-Villegas on the cohomology of character varieties with marked points. Their formula is identified with a refined BPS expansion in the stable pair theory of a local root stack, generalizing previous work of the first two authors in collaboration with Pan. Haiman's geometric construction for Macdonald polynomials is shown to emerge naturally in this context via geometric engineering. In particular this yields a new conjectural relation between Macdonald polynomials and refined local orbifold curve counting invariants. The string theoretic approach also leads to a new spectral cover construction for parabolic Higgs bundles in terms of holomorphic symplectic orbifolds.

Chuang, Wu-yen; Diaconescu, Duiliu-Emanuel; Donagi, Ron; Pantev, Tony

2014-11-01

194

Parabolic dunes in north-eastern Brazil  

E-print Network

In this work we present measurements of vegetation cover over parabolic dunes with different degree of activation along the north-eastern Brazilian coast. We are able to extend the local values of the vegetation cover density to the whole dune by correlating measurements with the gray-scale levels of a high resolution satellite image of the dune field. The empirical vegetation distribution is finally used to validate the results of a recent continuous model of dune motion coupling sand erosion and vegetation growth.

Duran, O; Bezerra, L J C; Herrmann, H J; Maia, L P

2007-01-01

195

Nonlinear modes in a complex parabolic potential  

SciTech Connect

We report on analysis of the mode structure of a Bose-Einstein condensate loaded in a complex parabolic potential and subjected to a constant pump. Stationary solutions for the positive and negative scattering lengths are addressed. In the case of a positive scattering length and large number of atoms the ground state is described by the Thomas-Fermi distribution, whose properties in the presence of the dissipation are very different from its conservative counterpart. It is shown that for a positive scattering length only the ground state appears to be stable.

Zezyulin, Dmitry A.; Alfimov, Georgy L. [Moscow Institute of Electronic Engineering, Zelenograd, Moscow RU-124498 (Russian Federation); Konotop, Vladimir V. [Centro de Fisica Teorica e Computacional, Universidade de Lisboa, Complexo Interdisciplinar, Avenida Professor Gama Pinto 2, Lisboa P-1649-003, Portugal, and Departamento de Fisica, Faculdade de Ciencias, Universidade de Lisboa, Campo Grande, Edificio C8, Piso 6, Lisboa P-1749-016 (Portugal)

2010-01-15

196

GREENHOUSE GAS ANALYSIS OF SOLAR-THERMAL ELECTRICITY GENERATION  

Microsoft Academic Search

Solar-thermal electricity generation contributes to climate change because it incurs the emission of greenhouse gases during the provision of services and the production of materials needed for the construction and operation of solar power plants. These greenhouse gas costs (GGC) can be determined using either material inventories in physical units or monetary cost breakdowns. Solar-only plants employing parabolic troughs, central

M. LENZEN

1999-01-01

197

Development of Non-Tracking Solar Thermal Technology  

Microsoft Academic Search

The aims of this research is to develop high temperature solar thermal collectors that do not require complex solar tracking devices to maintain optimal performance. The collector technology developed through these efforts uses non-imaging optics and is referred to as an external compound parabolic concentrator. It is able to operate with a solar thermal efficiency of approximately 50% at a

Roland Winston; Bruce Johnston; Kevin Balkowski

2011-01-01

198

Optical modeling for a two-stage parabolic trough concentrating photovoltaic\\/thermal system using spectral beam splitting technology  

Microsoft Academic Search

A two-stage parabolic trough concentrating photovoltaic\\/thermal (PV\\/T) system is described, which contains a concentrator, a spectral beam splitting filter, an evacuated collector tube and the solar cell components. The nondimensional optical model with the focal length of the concentrator as the characteristic length has been developed to analyze the properties of the concentrating system using the beam splitting filter. The

Shouli Jiang; Peng Hu; Songping Mo; Zeshao Chen

2010-01-01

199

Solid-dielectric compound parabolic concentrators: on their use with photovoltaic devices.  

PubMed

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

Goodman, N B; Ignatius, R; Wharton, L; Winston, R

1976-10-01

200

Heat and electricity from the sun using parabolic dish collector systems  

NASA Technical Reports Server (NTRS)

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.

Truscello, V. C.; Williams, A. N.

1979-01-01

201

Solar thermal aircraft  

DOEpatents

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.

Bennett, Charles L. (Livermore, CA)

2007-09-18

202

Parabolic subgroups of Chevalley groups over a commutative ring  

Microsoft Academic Search

This is a survey of results describing the parabolic subgroups of Chevalley groups over rings of various types. For Chevalley groups of classical types over an arbitrary commutative ring, a description of parabolic subgroups is obtained which may be considered definitive. Some errors in the results of V. M. Levchuk in Mat. Zametki, Volume 31, No. 4 (1982) are pointed

N. A. Vavilov

1984-01-01

203

JACQUET MODULES OF PARABOLICALLY INDUCED REPRESENTATIONS AND WEYL GROUPS  

E-print Network

JACQUET MODULES OF PARABOLICALLY INDUCED REPRESENTATIONS AND WEYL GROUPS DUBRAVKA BAN Abstract. Irreducible components of Jacquet modules with respect to induction in stages are given. The results are used for consideration of generalized Steinberg representations. 1. Introduction Jacquet modules of parabolically induced

Ban, Dubravka

204

Optimal Control for Degenerate Parabolic Equations with Logistic Growth*  

E-print Network

(x;t) of the population to be trapped is the control in our problem. We can treat zero Dirichlet (z = 0) or Neumann(no uxOptimal Control for Degenerate Parabolic Equations with Logistic Growth* by Suzanne M. Lenhart1 and Jiongmin Yong2 Abstract. This paper considers the optimal control of a degenerate parabolic partial dif

205

Optimal Control for Degenerate Parabolic Equations with Logistic Growth*  

E-print Network

) of the population to be trapped is the control in our problem. We can treat zero Dirichlet (z = 0) or Neumann (noOptimal Control for Degenerate Parabolic Equations with Logistic Growth* by Suzanne M. Lenhart 1 and Jiongmin Yong 2 Abstract. This paper considers the optimal control of a degenerate parabolic partial dif

206

Theory of parabolic pulse generation in tapered Anton I. Latkin  

E-print Network

and differences between high-power parabolic pulse generation in an active me- dium and in tapered fiber Optical Society of America OCIS codes: 060.2280, 060.4370, 060.5530, 320.5540. High-power pulseTheory of parabolic pulse generation in tapered fiber Anton I. Latkin Institute of Automation

Turitsyn, Sergei K.

207

THE PARABOLIC-PARABOLIC KELLER-SEGEL SYSTEM WITH CRITICAL DIFFUSION AS A GRADIENT FLOW IN Rd  

E-print Network

to describe the aggregation of cells by chemotaxis: the diffusion of the amoebae in a Petri dishTHE PARABOLIC-PARABOLIC KELLER-SEGEL SYSTEM WITH CRITICAL DIFFUSION AS A GRADIENT FLOW IN Rd , d 3-Segel system with critical porous-medium diffusion in dimension Rd , d 3 (also referred to as the quasilinear

Boyer, Edmond

208

Utility scale hybrid windsolar thermal electrical generation: A case study for Minnesota  

Microsoft Academic Search

The performance of a hybrid windsolar power plant in southwestern Minnesota is modeled for a 2-yr period using hourly wind and solar insolation data. The wind portion of the plant consists of four interconnected wind farms within a radius of 90km. The solar component of the plant is a parabolic trough solar thermal electric generating system using a heat transfer

J. P. Reichling; F. A. Kulacki

2008-01-01

209

Homogenization of a parabolic model of ferromagnetism  

NASA Astrophysics Data System (ADS)

This work deals with the homogenization of hysteresis-free processes in ferromagnetic composites. A degenerate, quasilinear, parabolic equation is derived by coupling the Maxwell-Ohm system without displacement current with a nonlinear constitutive law: {?B?}/{?t}+curl{A(x?)/?curlH?}=curlE, B????(H?,?). Here A is a periodic positive-definite matrix, ??(?,y) is maximal monotone and periodic in y, E is an applied field, and ?>0. An associated initial- and boundary-value problem is represented by a minimization principle via an idea of Fitzpatrick. As ??0 a two-scale problem is obtained via two-scale convergence, and an equivalent coarse-scale formulation is derived. This homogenization result is then retrieved via ?-convergence, and the continuity of the solution with respect to the operator ?? and the matrix A is also proved. This is then extended to some relaxation dynamics.

Visintin, Augusto

210

Dusty plasma experiments on parabolic flights  

NASA Astrophysics Data System (ADS)

Parabolic flights provide up to 20 seconds of weightlessness. This is sufficient time to produce volume-filling dusty plasmas and to study dynamic phenomena. Experimental parameters can be changed between parabolas and, in a three-day campaign comprising 90 parabolas, the research plan can be adjusted from day to day. The short turnaround times from planning to results make parabolic flights particularly attractive for university groups. The focus of our research is on self-excited dust density waves that are destabilized by ion flows. Studying linear and nonlinear waves also requires a detailed understanding of the dusty plasma environment. The same ion flow that destabilizes the waves is also responsible for the static forces on dust particles. Therefore, I will first describe the dusty plasma environment, in particular the formation of a large dust-free void. Experiments with dust tracers and comparison with simulations confirm the basic mechanisms that are at work. Direct measurement of forces on dust particles at the void edge became possible by laser manipulation. Second, I will describe the investigation of dust density waves by video-microscopy with fast digital cameras. Some unexpected phenomena are highlighted, like oblique modes and the formation of frequency clusters for nonlinear waves. Wave saturation by trapping of particles is demonstrated by reconstructing the phase space. The response of the plasma discharge to the presence of dust density waves is studied with simultaneous observations of dust density and plasma glow. At last, in a regime where the dust density wave is quenched by high gas friction, we have studied the elastic response of the dusty plasma to supersonic projectiles.

Piel, Alexander; Melzer, Andre

211

Comparison of Non-Parabolic Hydrodynamic Simulations for Semiconductor Devices  

NASA Technical Reports Server (NTRS)

Parabolic drift-diffusion simulators are common engineering level design tools for semiconductor devices. Hydrodynamic simulators, based on the parabolic band approximation, are becoming more prevalent as device dimensions shrink and energy transport effects begin to dominate device characteristic. However, band structure effects present in state-of-the-art devices necessitate relaxing the parabolic band approximation. This paper presents simulations of ballistic diodes, a benchmark device, of Si and GaAs using two different non-parabolic hydrodynamic formulations. The first formulation uses the Kane dispersion relationship in the derivation of the conservation equations. The second model uses a power law dispersion relation {(hk)(exp 2)/2m = xW(exp Y)}. Current-voltage relations show that for the ballistic diodes considered. the non-parabolic formulations predict less current than the parabolic case. Explanations of this will be provided by examination of velocity and energy profiles. At low bias, the simulations based on the Kane formulation predict greater current flow than the power law formulation. As the bias is increased this trend changes and the power law predicts greater current than the Kane formulation. It will be shown that the non-parabolicity and energy range of the hydrodynamic model based on the Kane dispersion relation are limited due to the binomial approximation which was utilized in the derivation.

Smith, A. W.; Brennan, K. F.

1996-01-01

212

Parabolic features and the erosion rate on Venus  

NASA Technical Reports Server (NTRS)

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.

Strom, Robert G.

1993-01-01

213

Water Use in Parabolic Trough Power Plants: Summary Results from WorleyParsons' Analyses  

SciTech Connect

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.

Turchi, C. S.; Wagner, M. J.; Kutscher, C. F.

2010-12-01

214

Non-local quasi-linear parabolic equations  

NASA Astrophysics Data System (ADS)

This is a survey of the most common approaches to quasi-linear parabolic evolution equations, a discussion of their advantages and drawbacks, and a presentation of an entirely new approach based on maximal L_p regularity. The general results here apply, above all, to parabolic initial-boundary value problems that are non-local in time. This is illustrated by indicating their relevance for quasi-linear parabolic equations with memory and, in particular, for time-regularized versions of the Perona-Malik equation of image processing.

Amann, H.

2005-12-01

215

Lightweight, low-cost solar energy collector  

NASA Technical Reports Server (NTRS)

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.

Hochberg, Eric B. (Inventor); Costen, Michael K. (Inventor)

2006-01-01

216

Potential for using parabolic trough collectors to supplement power cycle boilers  

NASA Astrophysics Data System (ADS)

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.

Schimmel, W. P., Jr.; Lukens, L. L.

1981-11-01

217

Detail, external parabolic antenna (later addition). Note how waveguide was ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

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

218

Antenna cab interior showing waveguide from external parabolic antenna (later ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

Antenna cab interior showing waveguide from external parabolic antenna (later addition), looking north. - Western Union Telegraph Company, Jennerstown Relay, Laurel Summit Road off U.S. 30, Laughlintown, Westmoreland County, PA

219

Space-Time Adaptive Wavelet Methods for Parabolic Evolution Problems  

E-print Network

(y)-w(x))(v(y)-v(x)) |x-y|3 dxdy, IR3 , X = Y = H 1 2()/R (hypersingular boundary integral equation). · Parabolic · Application to parabolic problems 1/39 #12;Adaptive wavelet methods 2/39 #12;Well-posed lin. op. eqs. Let X, Y of partial differential and integral operators, B is close to a sparse matrix, and f is close to sparse. We

Rauhut, Holger

220

Microphotonic parabolic light directors fabricated by two-photon lithography  

Microsoft Academic Search

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 mum high and 10 mum 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

J. H. Atwater; P. Spinelli; E. Kosten; J. Parsons; C. van Lare; J. van de Groep; J. Garcia de Abajo; A. Polman; H. A. Atwater

2011-01-01

221

Design and thermal analysis of a two stage solar concentrator for combined heat and thermoelectric power generation  

Microsoft Academic Search

A design procedure and thermal performance analysis of a two stage solar energy concentrator suited to combined heat and thermoelectric power generation are presented. The concentrator is comprised of a primary one axis parabolic trough concentrator and a second stage compound parabolic concentrator mounted at the focus of the primary. The thermoelectric device is attached to the absorber plate at

Siddig A. Omer; David G. Infield

2000-01-01

222

Operational Experience from Solar Thermal Energy Projects  

NASA Technical Reports Server (NTRS)

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.

Cameron, C. P.

1984-01-01

223

Prisms with total internal reflection as solar reflectors  

Microsoft Academic Search

In certain solar collectors, conventional mirrors can be replaced by an array of small rectangular glass prisms with total internal reflection (TIR). The suitability of TIR prismatic reflectors for solar energy collection is investigated systematically, and the following applications are found to be promising: (1) heliostats for central receiver; (2) parabolic reflectors with point focus; (3) line focus systems (both

A. Rabl

1976-01-01

224

Modeling and optimization of hybrid solar thermoelectric systems with thermosyphons  

Microsoft Academic Search

We present the modeling and optimization of a new hybrid solar thermoelectric (HSTE) system which uses a thermosyphon to passively transfer heat to a bottoming cycle for various applications. A parabolic trough mirror concentrates solar energy onto a selective surface coated thermoelectric to produce electrical power. Meanwhile, a thermosyphon adjacent to the back side of the thermoelectric maintains the temperature

Nenad Miljkovic; Evelyn N. Wang

2011-01-01

225

Prospects for the construction of solar furnaces for industry  

Microsoft Academic Search

The various techniques and prototype installations employed to absorb and concentrate solar energy for use in applications requiring 100-4000 C temperatures are explored. Mention is made of the Pericles heliostat field and the THEK distributed parabolic concentrator installations, and attention is focused on viable concepts useful for industrial purposes. The Odeillo solar furnace provided design guidelines and requirements for industrial

Ch. H. La Blanchetais

1982-01-01

226

Performance Study of the Solar Box type Stove using Two Phase Change Materials  

NASA Astrophysics Data System (ADS)

Solar cooker has not gained the popularity it deserves both in rural and urban India despite its obvious benefits and availability of plenty of sunny days. Some of the major limitations being: longer cooking time and non availability of the cooking facility during early morning and night hours. These drawbacks have been addressed in the present solar cooker by using a combination of two phase change materials (PCM) having melting temperatures in the range of 80-100C and 120-140C for efficient and sufficient storage of heat energy for extended cooking during night or early morning. The choice of PCM is decided by considering several factors which include melting temperature, latent heat capacity, and risk exposure to humans, water hazard and cost of the material. The right selection of PCM hence is very crucial in determining the performance and safety of operation. The optimization of increased solar flux with multiple reflectors, heat retention ability and utilization of heat conducting fins further reduces the cooking time considerably. An attempt has also been made to design tailor made cooking containers for good heat absorption from sun as well as good conduction of heat from PCM to containers during night cooking.

Bahal, Beni Madhaw

227

Optimized solar-powered liquid desiccant system to supply building fresh water and cooling needs  

Microsoft Academic Search

This paper studies the feasibility of using a solar-powered liquid desiccant system to meet both building cooling and fresh water needs in Beirut humid climate using parabolic solar concentrators as a heat source for regenerating the liquid desiccant. The water condensate is captured from the air leaving the regenerator. An integrated model of solar-powered calcium chloride liquid desiccant system for

N. Audah; N. Ghaddar; K. Ghali

2011-01-01

228

Development of mass-producible line-focus tracking concentrating solar collectors. Category 2: Control systems  

Microsoft Academic Search

The system design criteria and concept of a mass producible modular electronic control system for solar industrial process heating installations are discussed. The control system consists of: the master controller; the weather tower, including a solar tracking angle reference; and overtemperature switch, group control box, tracker\\/controller, and drive motor for each group of single axis tracking parabolic trough solar collectors.

T. E. Hickman

1984-01-01

229

Sunshape and its influence on the flux distribution in imaging solar concentrators  

Microsoft Academic Search

Imaging solar concentrators, such as a parabolic dish, image the sun to their focal plane. Thus, the flux distribution is basically an image of the angular distribution of the direct incident solar radiation. This distribution, referred to as sunshape, is determined by solar limb darkening and by small angle scattering in the atmosphere. The authors present measurements of the sunshape

M. Schubnell

1992-01-01

230

Development of a 75kW heat-pipe receiver for solar heat-engines  

Microsoft Academic Search

A program is now underway to develop commercial power conversion systems that use parabolic dish mirrors in conjunction with Stirling engines to convert solar energy to electric power. In early prototypes, the solar concentrator focused light directly on the heater tubes of the Stirling engine. Liquid-metal heat-pipes are now being developed to transfer energy from the focus of the solar

D. R. Adkins; C. E. Andraka; T. A. Moss

1995-01-01

231

Solar dish/engine systems  

SciTech Connect

Solar dish/engine systems convert the energy from the sun into electricity at a very high efficiency. Using a mirror array formed into the shape of a dish, the solar dish focuses the sun`s rays onto a receiver. The receiver transmits the energy to an engine that generates electric power. Because of the high concentration ratios achievable with parabolic dishes and the small size of the receiver, solar dishes are efficient at collecting solar energy at very high temperatures. Tests of prototype systems and components at locations throughout the US have demonstrated net solar to electric conversion efficiencies as high as 30%. This is significantly higher than any other solar technology.

Not Available

1998-04-01

232

The state of solar technology  

NASA Astrophysics Data System (ADS)

The difficulties and prospects of solar technology are discussed. The difficulties include the necessity of expensive and inefficient solar collectors and the low power density (a maximum 1 kW/sq m) which is an obstacle to achieving higher process temperatures and which necessitates the building of unusually extended installation. The prospects involve the generation of low temperature heat with flat-plate collectors, the generation of high temperature heat with concentrating collectors for the further transformation to mechanical or electrical energy, and the development of cheap solar cells for the direct generation of electrical energy from radiant energy. Measurements are shown for the amount of solar radiation received by various parts of the world, and the present solar technologies are reviewed including solar cells, flat plate collectors, parabolic cylinders, paraboloids and heliostat towers.

Kuczera, M.

1981-03-01

233

Advances in solar thermal electricity technology  

Microsoft Academic Search

Various advanced solar thermal electricity technologies are reviewed with an emphasis on new technology and new market approaches.In single-axis tracking technology, the conventional parabolic trough collector is the mainstream established technology and is under continued development but is soon to face competition from two linear Fresnel reflector (LFR) technologies, the CLFR and Solarmundo. A Solarmundo prototype has been built in

D. Mills

2004-01-01

234

Financing Solar Thermal Power Plants  

SciTech Connect

The commercialization of concentrating solar power technology took a major step forward in the mid 1980s and early 1990s with the development of the SEGS plants in California. Over the years they have proven that parabolic trough power technologies are the most cost-effective approach for commercial scale solar power generation in the sunbelt countries of the world. However, the question must be asked why no additional solar power plants have been build following the bankruptcy of the developer of the SEGS projects, LUZ International Limited. Although many believe the SEGS projects were a success as a result of parabolic trough technology they employ, in truth, the SEGS projects were developed simply because they represented an attractive opportunity for investors. Simply stated, no additional projects have been developed because no one has been able to put together a similarly attractive financial package to potential investors. More than $1.2 billion in private capital was raised i n debt and equity financing for the nine SEGS plants. Investors and bankers who make these investments are the real clients for solar power technologies. They are not interested in annual solar to electric efficiencies, but in risk, return on investments, and coverage ratios. This paper will take a look at solar power projects from the financier's perspective. The challenge in moving forward is to attract private investors, commercial lenders, and international development agencies and to find innovative solutions to the difficult issues that investment in the global power market poses for solar power technologies.

Price, H. W.; Kistner, R.

1999-11-01

235

Annular solar receiver thermal characteristics  

NASA Astrophysics Data System (ADS)

Results from thermal studies performed for an annular solar receiver assembly to be used with the 2 m, 90 deg parabolic collector trough are presented. The receiver configuration modeled consists of a 2.54 cm o.d. steel tube with a black chrome selective surface and an enclosing concentric Pyrex glass envelope. Previous thermal work conducted on the parabolic cylindrical collector design established the geometry and solar noon absorbed flux distribution used. One and two dimensional thermal models were developed to provide receiver assembly temperatures, heat losses, and working fluid energy extraction data with the Therminol-66 (T-66) bulk temperature maintained at 315 C. Parameters varied in the work include wind velocity, ambient air temperature, annulus gas pressure, and T-66 flow condition (Reynolds number). Heat loss and energy extraction results are tabulated and temperature distributions from two dimensional thermal modeling are graphically presented.

Ratzel, A. C.; Sisson, C. E.

1980-10-01

236

76 FR 65532 - Notice of Availability of the Final Environmental Impact Statement for the Proposed Sonoran Solar...  

Federal Register 2010, 2011, 2012, 2013

...3283 Enhancing Renewable Energy Development on the Public...and 3285A1 Renewable Energy Development by the Department...parabolic trough solar thermal technology to produce...8-inch pipeline. A thermal energy storage (TES)...

2011-10-21

237

Current and Future Costs for Parabolic Trough and Power Tower Systems in the US Market: Preprint  

SciTech Connect

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.

Turchi, C.; Mehos, M.; Ho, C. K.; Kolb, G. J.

2010-10-01

238

Current and future costs for parabolic trough and power tower systems in the US market.  

SciTech Connect

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.

Turchi, Craig (National Renewable Energy Laboratory, Golden, CO); Kolb, Gregory J.; Mehos, Mark Steven (National Renewable Energy Laboratory, Golden, CO); Ho, Clifford Kuofei

2010-08-01

239

Air Brayton Solar Receiver, phase 1  

NASA Technical Reports Server (NTRS)

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.

Zimmerman, D. K.

1979-01-01

240

Temperature Controller for a Solar Furnace  

NASA Technical Reports Server (NTRS)

Relatively-simple movable sheild has been suggested for controlling temperature of solar furnace. Temperature modulator can be set to have collected solar energy fully "on", fully "off" or any intermediate level. Parabolic mirror concentrates Sunlight into receiver. Shade plate that blocks insolation at back of receiver produces shade zone in center of collector. No radiation is returned to receiver from shade zone; only rays falling on other areas of reflecting surface are directed back toward receiver.

Hale, R. R.; Mcdougal, A. R.

1982-01-01

241

Wavepacket reconstruction via local dynamics in a parabolic lattice  

E-print Network

We study the dynamics of a wavepacket in a potential formed by the sum of a periodic lattice and of a parabolic potential. The dynamics of the wavepacket is essentially a superposition of ``local Bloch oscillations'', whose frequency is proportional to the local slope of the parabolic potential. We show that the amplitude and the phase of the Fourier transform of a signal characterizing this dynamics contains information about the amplitude and the phase of the wavepacket at a given lattice site. Hence, {\\em complete} reconstruction of the the wavepacket in the real space can be performed from the study of the dynamics of the system.

Quentin Thommen; Veronique Zehnle; Jean Claude Garreau

2002-03-06

242

Natural convective studies within a compound parabolic concentrator enclosure  

SciTech Connect

The contribution due to natural convection within a compound parabolic concentrator enclosure has been experimentally determined. These studies have been conducted within a truncated compound parabolic concentrator having a concentration ratio of 4, a receiver width of 3.175 cm, and a length of 244.0 cm. The receiver was heated electrically while the aperture was provided with a duct that was cooled by water. The limbs of the collector were fabricated from aluminum. Temperatures were directly obtained with copper constantan thermocouples located throughout the entire enclosure and provided the basis needed to calculate the different modes of heat transfer. The constant heat flux

Tatara, R.A.

1983-01-01

243

Accelerating Airy beams with non-parabolic trajectories  

NASA Astrophysics Data System (ADS)

A class of Airy accelerating beams with non-parabolic trajectories are derived by means of a novel application of a conformal transformation originally due to Bateman. It is also shown that the salient features of these beams are very simply incorporated in a solution which is derived by applying a conventional conformal transformation together with a Galilean translation to the basic accelerating Airy beam solution of the two-dimensional paraxial equation. Motivation for the non-parabolic beam trajectories is provided and the effects of finite-energy requirements are discussed.

Besieris, Ioannis M.; Shaarawi, Amr M.

2014-11-01

244

Electromagnetic Casimir forces of parabolic cylinder and knife-edge geometries  

E-print Network

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 ...

Graham, Noah

245

CONTINUOUS DEPENDENCE ESTIMATES FOR VISCOSITY SOLUTIONS OF FULLY NONLINEAR DEGENERATE PARABOLIC EQUATIONS  

E-print Network

CONTINUOUS DEPENDENCE ESTIMATES FOR VISCOSITY SOLUTIONS OF FULLY NONLINEAR DEGENERATE PARABOLIC for viscosity solutions of fully nonlinear degenerate parabolic equations with time and space dependent for the vanishing viscosity method. Finally, we illustrate the results (i) { (iii) on the Hamilton

Soatto, Stefano

246

Solar thermal energy systems industrial applications assessment review: presentation summaries  

SciTech Connect

Eighteen presentation summaries consisting mainly of view-graphs and including some brief verbal explanation are compiled. They cover: solar thermal energy applications assessment and planning; industrial sector analysis in the industrial applications branch of SERI; regional assessment studies, an evaluation of solar thermal systems for thermal applications, central receiver market studies; assessment of solar central receiver technology, markets, and industry; industrial solar thermal market assessment; solar industrial process heat market for central receiver technology; solar total energy modularity; parabolic dishes; solar industrial process heat case studies market evaluation; economic potential of solar thermal energy to provide industrial process heat in the US; industrial solar process heat program at the Northeast Solar Energy Center; the Gas Research Institute Program projections of industrial end uses to assist evaluation of solar thermal options; conventional approaches to industrial marketing; solar energy incentives and buyer behavior; and financial aspects for commercialization of central receivers. (LEW)

Not Available

1981-12-01

247

Concentrating Solar Power Program  

NSDL National Science Digital Library

This information resource related to renewable energy has recently been made available by the US Department of Energy. The Concentrating Solar Power Program is researching solar thermal technologies in order to provide future energy, economic, and environmental security for the US. This site provides an overview of the program, the program's strategic plan, and an analysis of the three technologies being researched: the power tower, dish/engine, and parabolic trough systems. Cost and performance analysis results for each technology are included (Adobe Acrobat [.pdf] format only). [Notes: Originally reviewed in conjunction with other resources. To read the full review, link to the archived Scout Report via the Date of Review above. Site formerly known as "Solar Thermal Electric Program (STEP)."

1997-01-01

248

Solar thermal technology  

NASA Astrophysics Data System (ADS)

This annual report describes the accomplishments and progress of government-funded activities initiated, renewed, or completed during Fiscal Year (FY) 1987 (October 1, 1986, through September 30, 1987). It highlights the program tasks conducted by participating federal laboratories and by industrial, academic, or other research under a subcontract. The emphasis of the Solar Thermal Technology Program during the year was: (1) to perform research and development leading to the economic viability of two primary solar thermal concepts, central receiver and parabolic dish, and (2) to explore applications of national significance where the special attributes of concentrated sunlight are appropriate. The report includes three appendices that cover principal contacts and sources of additional information (Appendix A), acronyms and abbreviations (Appendix B), and a glossary of terms (Appendix C). A bibliography of relevant publications from Sandia National Laboratories and the Solar Energy Research Institute completes this annual report.

1988-09-01

249

Build an oven, cook a meal: How solar energy empowered women in Costa Rica  

SciTech Connect

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.

Blankenship, J. (Canadian Univ. Service Organization, San Jose (Costa Rica))

1990-12-01

250

An Application of Calculus: Optimum Parabolic Path Problem  

ERIC Educational Resources Information Center

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

Atasever, Merve; Pakdemirli, Mehmet; Yurtsever, Hasan Ali

2009-01-01

251

Symmetry properties of positive solutions of parabolic equations: a survey  

E-print Network

Symmetry properties of positive solutions of parabolic equations: a survey P. Pol´acik School certain reflectional symmetries, the presented results show how positive solutions reflect the symmetries. Depending on the class of solutions con- sidered, the symmetries for all times or asymptotic symmetries

Polacik, Peter

252

A note on fractional parabolic differential and difference equations  

NASA Astrophysics Data System (ADS)

In this work, the first and second order of difference schemes that approximately solve the initial-boundary value problem for multidimensional fractional parabolic equation with Dirichlet boundary condition are presented. The stability estimates for the solution of these difference schemes are established.

Ashyralyev, Allaberen; Artykov, Merdan; Cakir, Zafer

2014-08-01

253

Vacuum Solutions of Einstein's Equations in Parabolic Coordinates  

E-print Network

We present a simple method to obtain vacuum solutions of Einstein's equations in parabolic coordinates starting from ones with cylindrical symmetries. Furthermore, a generalization of the method to a more general situation is given together with a discussion of the possible relations between our method and the Belinsky-Zakharov soliton-generating solutions.

Stefano Viaggiu

2004-06-14

254

Parabolic Harnack Inequality and Local Limit Theorem for Percolation Clusters  

Microsoft Academic Search

We consider the random walk on supercritical percolation clusters in the d-dimensional Euclidean lattice. Previous papers have obtained Gaussian heat kernel bounds, and a.s. invariance principles for this process. We show how this information leads to a parabolic Harnack inequality, a local limit theorem and estimates on the Green's function.

Martin Barlow; Ben Hambly

2008-01-01

255

Orthostatic Intolerance and Motion Sickness After Parabolic Flight  

NASA Technical Reports Server (NTRS)

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.

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

256

Parabolic Equations on Uniformly Regular Riemannian Manifolds and Degenerate  

E-print Network

Problems Herbert Amann Dedicated to Professor Yoshihiro Shibata on the occasion of his sixtieth birthday problems for lin- ear parabolic equations on a wide class of noncompact Riemannian manifolds, termed and the appendix. #12;2 Herbert Amann Let M = (M, g) be a Riemannian manifold. We set Au := - div(a q grad u), (1

Amann, Herbert

257

Long-term average performance benefits of parabolic trough improvements  

SciTech Connect

Improved parabolic trough concentrating collectors will result from better design, improved fabrication techniques, and the development and utilization of improved materials. The difficulty of achieving these improvements varies as does their potential for increasing parabolic trough performance. The purpose of this analysis is to quantify the relative merit of various technology advancements in improving the long-term average performance of parabolic trough concentrating collectors. The performance benefits of improvements are determined as a function of operating temperature for north-south, east-west, and polar mounted parabolic troughs. The results are presented graphically to allow a quick determination of the performance merits of particular improvements. Substantial annual energy gains are shown to be attainable. Of the improvements evaluated, the development of stable back-silvered glass reflective surfaces offers the largest performance gain for operating temperatures below 150/sup 0/C. Above 150/sup 0/C, the development of trough receivers that can maintain a vacuum is the most significant potential improvement. The reduction of concentrator slope errors also has a substantial performance benefit at high operating temperatures.

Gee, R.; Gaul, H.W.; Kearney, D.; Rabl, A.

1980-03-01

258

Transient analysis of lossy parabolic transmission lines with nonlinear loads  

Microsoft Academic Search

The exact analytical expressions of the time-domain step response matrix parameters for the lossy parabolic transmission line are developed, therefore extending the range of problems where Allen's method can be applied for the transient analysis of networks consisting of interconnections of linear distributed elements, lumped linear and\\/or nonlinear elements, and arbitrary sources. For completeness, similar expressions are derived for the

Pierre Bouchard; R. R. J. Gagne

1995-01-01

259

MOP --ALGORITHMIC MODALITY ANALYSIS FOR PARABOLIC GROUP ACTIONS  

E-print Network

MOP -- ALGORITHMIC MODALITY ANALYSIS FOR PARABOLIC GROUP ACTIONS ULF J ? URGENS AND GERHARD R on the Lie algebra p u of its unipotent radical P u via the adjoint action. The modality of this action, mod generally, we also consider the modality of the action of P on an invariant subspace n of p u , that is mod

Bielefeld, University of

260

A zonal equation method for parabolic-elliptic flows  

Microsoft Academic Search

Viscous fluid flow is governed by the full Navier-Stokes equations for which solution is both difficult and expensive. The incompressible equations are elliptic, butr parabolizing asumptions can be made under certain conditions, leading to various boundary layer and space-marching formulations which can greatly economize the solution procedure. Generally, the formulation which is valid for the most complex region of a

M. J. Warfield

1986-01-01

261

ADVANCED PRECIPITATION RADAR ANTENNA SINGLY CURVED PARABOLIC ANTENNA REFLECTOR DEVLEOPMENT  

Microsoft Academic Search

NASA and JPL have recognized space inflatable and thin film technologies as the enabling innovations for the advancement of the next generation of Advanced Precipitation Radar Antenna (APRA). 1,2 However, the utilization of these Gossamer technologies in this type of application (i.e. a large thin film parabolic cylindrical reflector deployed and supported by a space inflatable structure) has never been

John K. Lin; George H. Sapna III; Stephen E. Scarborough; Bernardo C. Lopez

2003-01-01

262

The dynamics of parabolic flight: flight characteristics and passenger percepts.  

PubMed

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

Karmali, Faisal; Shelhamer, Mark

2008-09-01

263

The dynamics of parabolic flight: Flight characteristics and passenger percepts  

NASA Astrophysics Data System (ADS)

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 s of freefall (0 g) followed by 40 s 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.

Karmali, Faisal; Shelhamer, Mark

2008-09-01

264

Canadian low-gravity research using parabolic aircraft  

Microsoft Academic Search

An active experimental program being implemented by Canada in microgravity, which relies heavily on the use of parabolic aircraft, is discussed. The advantages of zero-gravity aircraft include low cost and quick turnaround. These aircraft have demonstrated their value for prototyping experimental hardware developments planned for flight at other facilities, such as sounding rockets and Shuttle-based carriers which are supported by

Glen S. Campbell; L. Vezina; J. F. Aitken

1992-01-01

265

PARABOLIC ISOMETRIES OF CAT(0) SPACES AND CAT(0) DIMENSIONS  

E-print Network

PARABOLIC ISOMETRIES OF CAT(0) SPACES AND CAT(0) DIMENSIONS KOJI FUJIWARA, TAKASHI SHIOYA proper CAT(0) spaces of dimension 2 by isometries, although such actions exist on CAT(0) spaces is isometric to H n C . It is a CAT(-1) space of dimension 2n. The geometric dimension of G is 2n- 1. We show

Fujiwara, Koji

266

IR Spectrometer Using 90-Degree Off-Axis Parabolic Mirrors  

SciTech Connect

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 15004500 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 arrays 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.

Robert M. Malone, Ian J. McKenna

2008-03-01

267

IR Spectrometer Using 90-degree Off-axis Parabolic Mirrors  

SciTech Connect

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 15004500 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 arrays 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.

Robert M. Malone, Richard, G. Hacking, Ian J. McKenna, and Daniel H. Dolan

2008-09-02

268

Electromagnetic Casimir Forces of Parabolic Cylinder and Knife-Edge Geometries  

E-print Network

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.

Graham, Noah; Emig, Thorsten; Rahi, Sahand Jamal; Jaffe, Robert L; Kardar, Mehran

2011-01-01

269

Electromagnetic Casimir Forces of Parabolic Cylinder and Knife-Edge Geometries  

E-print Network

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.

Noah Graham; Alexander Shpunt; Thorsten Emig; Sahand Jamal Rahi; Robert L. Jaffe; Mehran Kardar

2011-03-30

270

Textile drying using solarized cylindrical can dryers to demonstrate the application of solar energy to industrial drying or dehydration processes: Phase I. Final report  

Microsoft Academic Search

The detailed design of a solar energy collection system for providing process heat to a textile drying process is described. The solar collection subsystem uses 773 square meters (8313 square feet) of parabolic trough, single axis tracking, concentrating collectors to heat water in a high temperature water (HTW) loop. At the 2:00 pm September 21 time point (clear day) the

P. D. Mitchell; B. P. Gupta; K. L. Curtner; R. A. Rausch

1977-01-01

271

Doubling the concentration of one-axis tracking parabolic trough collectors by a new second-stage design  

SciTech Connect

Economic operation of high-efficiency concentrator solar cells requires solar concentration ratios which up to now can only be achieved with two-axis tracking. In this paper the authors present a two-stage concentrator approaching concentration ratios up to 300X while being tracked around only one polar axis. Its principle is as follows: A parabolic trough focuses the direct solar radiation onto a line parallel to the polar tracking axis. The half rim angle of this first concentrating stage is chosen to be equal to the sun`s maximum declination of 23.5{degree}. The second stage consists of a row of dielectric, nonimaging 3D-concentrators, which couple the concentrated light directly into square solar cells. The proposed design makes use of the limited divergence of {+-}23.5{degree} in the NS-direction which still can be concentrated by a factor of n/sin(23.5{degree}). The performance of the system depends sensitively on how well the angular acceptance characteristic of the second stage matches with the square-shaped angular irradiance distribution in the focal line of the parabolic trough. A new concentrator profile has been found that exhibits an almost ideal square acceptance characteristic with a very sharp cut-off. It is longer than the standard CPC and its slope is reduced towards the exit of the concentrator. A prototype two-stage concentrator has been constructed with a total geometrical concentration of 214X. In outdoor measurements a total optical efficiency of 77.5% was obtained.

Brunotte, M.; Goetzberger, A.; Blieske, U. [Fraunhofer Inst. for Solar Energy Systems, Freiburg (Germany)

1994-12-31

272

Research and Development of a Low Cost Solar Collector  

SciTech Connect

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

Ansari, Asif; Philip, Lee; Thouppuarachchi, Chirath

2012-08-01

273

Application of solar thermal energy to buildings and industry  

SciTech Connect

Flat plate collectors and evacuated tube collectors are described, as are parabolic troughs, Fresnel lenses, and compound parabolic concentrators. Use of solar energy for domestic hot water and for space heating and cooling are discussed. Some useful references and methods of system design and sizing are given. This includes mention of the importance of economic analysis. The suitability of solar energy for industrial use is discussed, and solar ponds, point-focus receivers and central receivers are briefly described. The use of solar energy for process hot water, drying and dehydration, and process steam are examined, industrial process heat field tests by the Department of Energy are discussed, and a solar total energy system in Shenandoah, GA is briefly described. (LEW)

Kutscher, C. F.

1981-05-01

274

Development and testing of Parabolic Dish Concentrator No. 1  

NASA Technical Reports Server (NTRS)

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.

Dennison, E. W.; Thostesen, T. O.

1984-01-01

275

Warsaw Catalogue of cometary orbits: 119 near-parabolic comets  

E-print Network

Context. The dynamical evolution of near-parabolic comets strongly depends on the starting values of the orbital elements derived from the positional observations. In addition, when drawing conclusions about the origin of these objects, it is crucial to control the uncertainties of orbital elements at each stage of the dynamical evolution. Aims. I apply a completely homogeneous approach to determine the cometary orbits and their uncertainties. The resulting catalogue is suitable for the investigation of the origin and future of near-parabolic comets. Methods. First, osculating orbits were determined on the basis of positional data. Second, the dynamical calculations were performed backwards and forwards up to 250 au from the Sun to derive original and future barycentric orbits for each comet. In the present investigation of dynamical evolution, the numerical calculations for a given object start from the swarm of virtual comets constructed using the previously determined osculating (nominal) orbit. In this wa...

Krlikowska, Ma?gorzata

2014-01-01

276

Practical limits of the parabolic approximation for focused ultrasound beams  

NASA Astrophysics Data System (ADS)

Applying the parabolic approximation to the wave equation results in a far simpler and more tractable model for ultrasound propagation. The approximate (Kuznetsov)model assumes that sound propagates predominantly in the axial direction and that the pressure amplitude is a slowly varying function of the axial coordinate. Since the terms "predominantly" and "slowly" ar far from quantitative descriptors, and since recent work shows excellent agreement between simulation and experiment at surprisingly low F-numbers, the presentwork seeks tomore firmly establish the region of validity of this approximation for focused ultrasound sources. To this end, the focused beam of a flat panel transducer is modeled using both the full wave equation and its parabolic approximation. The simulation results are compared as a function of focusing depth and beam steering angle.

Soneson, Joshua E.

2012-10-01

277

Dirac mass dynamics in a multidimensional nonlocal parabolic Alexander Lorz  

E-print Network

is that solutions concentrate as Dirac masses n(t, x) ¯(t) x - ¯x(t) . For equation (1.1), we can give an intuitive(2)! Dirac concentration points are un- derstood as maximum points of u(t, x) in (1.4). As it is wellDirac mass dynamics in a multidimensional nonlocal parabolic equation Alexander Lorz Sepideh

Boyer, Edmond

278

Hermitian-einstein metrics on parabolic stable bundles  

Microsoft Academic Search

Let \\u000a $$\\\\overline M $$\\u000a be a compact complex manifold of complex dimension two with a smooth Khler metric and D a smooth divisor on \\u000a $$\\\\overline M $$\\u000a . If E is a rank 2 holomorphic vector bundle on \\u000a $$\\\\overline M $$\\u000a with a stable parabolic structure along D, we prove the existence of a metric on \\u000a $$E'{\\\\text{ = }}E|_{\\\\overline M

Jiayu Li; M. S. Narasimhan

1999-01-01

279

Stationary flows of the parabolic potential barrier in two dimensions  

Microsoft Academic Search

In the two-dimensional isotropic parabolic potential barrier V(x,y) = V0-mgamma2(x2 + y2)\\/2, though it is a model of an unstable system in quantum mechanics, we can obtain the stationary states corresponding to the real energy eigenvalue V0. Further, they are infinitely degenerate. For the first few eigenstates, we will find the stationary flows round a right angle that are expressed

Toshiki Shimbori; Tsunehiro Kobayashi

2000-01-01

280

Optimal feedback control infinite dimensional parabolic evolution systems: Approximation techniques  

NASA Technical Reports Server (NTRS)

A general approximation framework is discussed for computation of optimal feedback controls in linear quadratic regular problems for nonautonomous parabolic distributed parameter systems. This is done in the context of a theoretical framework using general evolution systems in infinite dimensional Hilbert spaces. Conditions are discussed for preservation under approximation of stabilizability and detectability hypotheses on the infinite dimensional system. The special case of periodic systems is also treated.

Banks, H. T.; Wang, C.

1989-01-01

281

A nonlinear parabolic equation with a nonlocal boundary term  

NASA Astrophysics Data System (ADS)

A nonlinear parabolic problem with a nonlocal boundary condition is studied. We prove the existence of a solution for a monotonically increasing and Lipschitz continuous nonlinearity. The approximation method is based on Rothe's method. The solution on each time step is obtained by iterations, convergence of which is shown using a fixed-point argument. The space discretization relies on FEM. Theoretical results are supported by numerical experiments.

Slodicka, Marin; Dehilis, Sofiane

2010-04-01

282

Discontinuous Galerkin Finite Element Method for Parabolic Problems  

NASA Technical Reports Server (NTRS)

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.

Kaneko, Hideaki; Bey, Kim S.; Hou, Gene J. W.

2004-01-01

283

Moments and Lyapunov exponents for the parabolic Anderson model  

E-print Network

We study the parabolic Anderson model in $(1+1)$ dimensions with nearest neighbor jumps and space-time white noise (discrete space/continuous time). We prove a contour integral formula for the second moment and compute the second moment Lyapunov exponent. For the model with only jumps to the right, we prove a contour integral formula for all moments and compute moment Lyapunov exponents of all orders.

Alexei Borodin; Ivan Corwin

2014-04-28

284

A technique for comparing parabolic trough photovoltaic performance  

Microsoft Academic Search

An analysis was performed to predict the power outputs of 4- and 7-foot aperture linear parabolic troughs. The analysis was part of a trade-off study to reduce the cost of the BDM 47 kW concentrating PV applications experiment (PRDA-35) by using fewer larger aperture collectors. The key feature of the analysis was the use of laser scans of the troughs

T. J. Lambarski; J. A. Higbie; C. B. Rogers

1981-01-01

285

PARABOLIC EQUATIONS OVER THE FIELD OF p-ADIC NUMBERS  

NASA Astrophysics Data System (ADS)

The author constructs and investigates a fundamental solution of Cauchy's problem for a parabolic equation with a p-adic space variable and a real time variable. The question of existence and uniqueness of solutions to Cauchy's problem in classes of bounded and increasing functions is considered, and conditions for nonnegativity of the fundamental solution are found. The problem of determining if the solution stabilizes as t \\to \\infty is solved for a model equation with constant coefficients.

Kochube?, A. N.

1992-06-01

286

Synergies between optical and physical variables in intercepting parabolic targets  

PubMed Central

Interception requires precise estimation of time-to-contact (TTC) information. A long-standing view posits that all relevant information for extracting TTC is available in the angular variables, which result from the projection of distal objects onto the retina. The different timing models rooted in this tradition have consequently relied on combining visual angle and its rate of expansion in different ways with tau being the most well-known solution for TTC. The generalization of these models to timing parabolic trajectories is not straightforward. For example, these different combinations rely on isotropic expansion and usually assume first-order information only, neglecting acceleration. As a consequence no optical formulations have been put forward so far to specify TTC of parabolic targets with enough accuracy. It is only recently that context-dependent physical variables have been shown to play an important role in TTC estimation. Known physical size and gravity can adequately explain observed data of linear and free-falling trajectories, respectively. Yet, a full timing model for specifying parabolic TTC has remained elusive. We here derive two formulations that specify TTC for parabolic ball trajectories. The first specification extends previous models in which known size is combined with thresholding visual angle or its rate of expansion to the case of fly balls. To efficiently use this model, observers need to recover the 3D radial velocity component of the trajectory which conveys the isotropic expansion. The second one uses knowledge of size and gravity combined with ball visual angle and elevation angle. Taking into account the noise due to sensory measurements, we simulate the expected performance of these models in terms of accuracy and precision. While the model that combines expansion information and size knowledge is more efficient during the late trajectory, the second one is shown to be efficient along all the flight. PMID:23720614

Gmez, Jos; Lpez-Moliner, Joan

2013-01-01

287

Circulatory filling pressures during transient microgravity induced by parabolic flight  

NASA Technical Reports Server (NTRS)

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.

Latham, Ricky D.; Fanton, John W.; White, C. D.; Vernalis, Mariana N.; Crisman, R. P.; Koenig, S. C.

1993-01-01

288

Sympathetic nerve response to microgravity induced by parabolic flight.  

PubMed

The aim of this study was to clarify how muscle sympathetic nerve activity (MSNA) in humans, which plays an important role in blood pressure control against gravity, is altered under microgravity conditions. Subjects were seated in a jet aircraft with their legs extended. MSNA was recorded microneurographically from the tibial nerve of the sitting subjects with simultaneous monitoring of electrocardiogram, blood pressure, respiration, and intrathoracic blood volume during parabolic flights. In the Air Force training area, the aircraft made parabolas up to 10 times. At the entry to microgravity, intrathoracic blood volume increased, systemic blood pressure was elevated, and MSNA was suppressed. However, this MSNA suppression lasted only 10-15 sec, and then followed by an enhancement to the end of the parabolas. We conclude that MSNA is suppressed at the onset of microgravity during parabolic flight in response to loading of the cardiopulmonary volume receptor due to a cephalad body fluid shift. However, this MSNA suppression is transient during such dynamic gravitational changes as those induced by parabolic flight, probably modulated by arterial baroreceptors. PMID:11541505

Iwase, S; Cui, J; Kitazawa, H; Miyazaki, S; Sugiyama, Y; Kohno, M; Mukai, C; Mano, T

1997-12-01

289

Solar heating system  

SciTech Connect

A system is disclosed for collection of solar energy by one or more reflectors which concentrate the suns rays on liquid circulating pipes which is part of a collecting and storing system for solar heated liquid to replace or supplement usual sources of heat in heating systems. More specifically, the system comprises one or more bent, preferably parabolic reflectors pivotly mounted on black heat absorbing pipes through which liquid circulates to absorb heat energy from the sun. The reflectors and the pipes are mounted in an open space such as a building roof with adjusting mechanism to pivot and fix the reflectors in different positions. Transparent plates bridge the space between the edges of the reflectors with hooked cross straps to hold the assembly together.

White, G.

1980-03-18

290

Comparison of solar technologies for driving a desalination system by means of an organic Rankine cycle  

Microsoft Academic Search

In a previous paper the authors analyzed a low power (100 kW) solar organic Rankine cycle (ORC) as the mechanical and thermal energy source for desalination processes. Such a solar ORC is powered by parabolic trough collectors with direct vapor generation (DVG) technology. To this day, however, there are still no commercial implementations of said technology. For this reason, in

Agustn Manuel Delgado-Torres; Lourdes Garca-Rodrguez

2007-01-01

291

SOLAR FIBER-OPTIC MINI-DISHES: A NEW APPROACH TO THE EFFICIENT COLLECTION OF SUNLIGHT  

Microsoft Academic Search

A new concept for efficient solar energy concentration and power delivery is proposed one that offers substantial advantages in efficiency, compactness, reduced mechanical loads, and ease of fabrication and installation relative to conventional solar designs. The design exploits the availability of low-attenuation optical fibers, as well as the practical advantages of mass producing highly accurate very small parabolic dishes.

Daniel Feuermann; Jeffrey M. Gordon

1999-01-01

292

The calculation and analysis of glass-to-metal sealing stress in solar absorber tube  

Microsoft Academic Search

The failure or degradation of solar absorber tubes is the single largest cost factor for current parabolic trough solar power plant. The main failure reason is that there are residual stresses in the glass-to-metal joint which are generated during the cooling process of sealing. According to the thin shell theory and thermal stress theory, this paper presents the analytic solution

Dongqiang Lei; Zhifeng Wang; Jian Li

2010-01-01

293

Solar powered adsorption refrigerator with CPC collection system: Collector design and experimental test  

Microsoft Academic Search

Solar adsorption cooling systems are usually based on the flat plate collector, whereas little attention has been paid to concentrating collectors. Compound parabolic concentrators (CPC) are a versatile class of solar collectors that can be adapted to a large variety of applications and geometries. This work presents a CPC collector whose tubular receiver contains the sorption bed and where only

Manuel I. Gonzlez; Luis R. Rodrguez

2007-01-01

294

Solar power water distillation unit  

NASA Astrophysics Data System (ADS)

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].

Hameed, Kamran; Muzammil Khan, Muhammad; Shahrukh Ateeq, Ijlal; Omair, Syed Muhammad; Ahmer, Muhammad; Wajid, Abdul

2013-06-01

295

Derivation and application of extended parabolic wave theories. II. Path integral representations  

NASA Astrophysics Data System (ADS)

The n-dimensional reduced scalar Helmholtz equation for a transversely inhomogeneous medium is naturally related to parabolic propagation models through (1) the n-dimensional extended parabolic (Weyl pseudodifferential) equation and (2) an imbedding in an (n+1)-dimensional parabolic (Schrdinger) equation. The first relationship provides the basis for the parabolic-based Hamiltonian phase space path integral representation of the half-space propagator. The second relationship provides the basis for the elliptic-based path integral representations associated with Feynman and Fradkin, Feynman and Garrod, and Feynman and DeWitt-Morette. Exact and approximate path integral constructions are derived for the homogeneous and transversely inhomogeneous cases corresponding to both narrow- and wide-angle extended parabolic wave theories. The path integrals allow for a global perspective of the transition from elliptic to parabolic wave theory in addition to providing a unifying framework for dynamical approximations, resolution of the square root operator, and the concept of an underlying stochastic process.

Fishman, Louis; McCoy, John J.

1984-02-01

296

A hybrid reconfigurable solar and wind energy system  

Microsoft Academic Search

We study the feasibility of a novel hybrid solar-wind hybrid system that shares most of its infrastructure and components. During periods of clear sunny days the system will generate electricity from the sun using a parabolic concentrator. The concentrator is formed by individual mirror elements and focuses the light onto high intensity vertical multi-junction (VMJ) cells. During periods of high

Sagar A. Gadkari

2008-01-01

297

Performance and cost optimisation of small solar power stations  

Microsoft Academic Search

Small solar farm power systems using parabolic trough collectors and power conversion systems following the Rankine principle are discussed. Overall system efficiency is considered in terms of the selection of optimum operational temperature, storage size, and design day; it is noted that collector field efficiency drops with increasing temperature, while power conversion efficiency increases with higher temperature. Attention is also

J. E. Feustel

1979-01-01

298

Textile drying using solarized can dryers to demonstrate the application of solar energy to industrial drying or dehydration processes, Phase II. Final report  

Microsoft Academic Search

This program has resulted in the installation of a solar energy collection system for providing process heat to a textile drying process. The solar collection subsystem uses 700 square meters (7500 square feet) of parabolic trough, single-axis tracking, concentrating collectors to heat water in a high temperature water (HTW) loop. The solar collectors nominally generate 193°C (380°F) water with the

P. D. Mitchell; M. E. Beesing; G. L. Bessler

1979-01-01

299

Optimized concentrating\\/passive tracking solar collector. Final report  

Microsoft Academic Search

A concentrating solar collector having about half the material cost of other collectors with similar performance is described. The selected design is a Compound Parabolic Concentrator (CPC) which concentrates solar energy throughout the year without requiring realignment. Output is a fluid heated to 100°C with good efficiency. The optical design of the reflector surface was optimized, yielding a 2.0:1 concentration

K. E. Sterne; A. L. Johnson; R. H. Grotheer

1979-01-01

300

Error Analysis for Discontinuous Galerkin Method for Parabolic Problems  

NASA Technical Reports Server (NTRS)

In the proposal, the following three objectives are stated: (1) A p-version of the discontinuous Galerkin method for a one dimensional parabolic problem will be established. It should be recalled that the h-version in space was used for the discontinuous Galerkin method. An a priori error estimate as well as a posteriori estimate of this p-finite element discontinuous Galerkin method will be given. (2) The parameter alpha that describes the behavior double vertical line u(sub t)(t) double vertical line 2 was computed exactly. This was made feasible because of the explicitly specified initial condition. For practical heat transfer problems, the initial condition may have to be approximated. Also, if the parabolic problem is proposed on a multi-dimensional region, the parameter alpha, for most cases, would be difficult to compute exactly even in the case that the initial condition is known exactly. The second objective of this proposed research is to establish a method to estimate this parameter. This will be done by computing two discontinuous Galerkin approximate solutions at two different time steps starting from the initial time and use them to derive alpha. (3) The third objective is to consider the heat transfer problem over a two dimensional thin plate. The technique developed by Vogelius and Babuska will be used to establish a discontinuous Galerkin method in which the p-element will be used for through thickness approximation. This h-p finite element approach, that results in a dimensional reduction method, was used for elliptic problems, but the application appears new for the parabolic problem. The dimension reduction method will be discussed together with the time discretization method.

Kaneko, Hideaki

2004-01-01

301

Adaptive Grids For 3-D Parabolized Navier-Stokes Computations  

NASA Technical Reports Server (NTRS)

Computational grids adjusted iteratively to reduce errors. Procedure for iterative adjustment of computational grids developed for use in numerical solution of three-dimensional parabolized Navier-Strokes equations of flow. Refines grid in regions of high gradients in initial computed flow so on subsequent iterations, one can satisfy competing requirements to produce solution capturing pertinent features as shock waves and boundary layers, accurate resolution of which typically requires fine meshes; and prevent unnecessary refinement of mesh elsewhere, preventing undue increase in amount of computation.

Harvey, A. D.; Acharya, S.; Lawrence, S. L.

1992-01-01

302

Multifractality at the quantum Hall transition: beyond the parabolic paradigm.  

PubMed

We present an ultrahigh-precision numerical study of the spectrum of multifractal exponents Deltaq characterizing anomalous scaling of wave function moments |psi|2q at the quantum Hall transition. The result reads Deltaq=2q(1-q)[b0+b1(q-1/2)2+cdots, three dots, centered], with b0=0.1291+/-0.0002 and b1=0.0029+/-0.0003. The central finding is that the spectrum is not exactly parabolic: b1 not equal0. This rules out a class of theories of the Wess-Zumino-Witten type proposed recently as possible conformal field theories of the quantum Hall critical point. PMID:18851310

Evers, F; Mildenberger, A; Mirlin, A D

2008-09-12

303

Stationary Flows of the Parabolic Potential Barrier in Two Dimensions  

E-print Network

In the two-dimensional isotropic parabolic potential barrier $V(x, y)=V_0 -m\\gamma^2 (x^2+y^2)/2$, though it is a model of an unstable system in quantum mechanics, we can obtain the stationary states corresponding to the real energy eigenvalue $V_0$. Further, they are infinitely degenerate. For the first few eigenstates, we will find the stationary flows round a right angle that are expressed by the complex velocity potentials $W=\\pm\\gamma z^2/2$.

Shimbori, T; Shimbori, Toshiki; Kobayashi, Tsunehiro

2000-01-01

304

Stationary Flows of the Parabolic Potential Barrier in Two Dimensions  

E-print Network

In the two-dimensional isotropic parabolic potential barrier $V(x, y)=V_0 -m\\gamma^2 (x^2+y^2)/2$, though it is a model of an unstable system in quantum mechanics, we can obtain the stationary states corresponding to the real energy eigenvalue $V_0$. Further, they are infinitely degenerate. For the first few eigenstates, we will find the stationary flows round a right angle that are expressed by the complex velocity potentials $W=\\pm\\gamma z^2/2$.

Toshiki Shimbori; Tsunehiro Kobayashi

2000-06-05

305

A two cities theorem for the parabolic Anderson model  

Microsoft Academic Search

The parabolic Anderson problem is the Cauchy problem for the heat equation $\\\\partial_tu(t,z)=\\\\Delta u(t,z)+\\\\xi(z)u(t,z)$ on $(0,\\\\infty)\\\\times {\\\\mathbb{Z}}^d$ with random potential $(\\\\xi(z):z\\\\in{\\\\mathbb{Z}}^d)$. We consider independent and identically distributed potentials, such that the distribution function of $\\\\xi(z)$ converges polynomially at infinity. If $u$ is initially localized in the origin, that is, if $u(0,{z})={\\\\mathbh1}_0({z})$, we show that, as time goes to infinity, the

Wolfgang Knig; Hubert Lacoin; Peter Mrters; Nadia Sidorova

2011-01-01

306

Digital Foucault tester for the measurement of parabolic wave form  

NASA Astrophysics Data System (ADS)

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.

Wang, Xiao-peng; Zhu, Ri-hong; Wang, Lei

2009-07-01

307

Inhomogeneous parabolic equations on unbounded metric measure spaces  

E-print Network

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.

Kenneth J. Falconer; Jiaxin Hu; Yuhua Sun

2011-03-29

308

Parabolized Navier-Stokes methods for hypersonic flows  

NASA Technical Reports Server (NTRS)

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.

Lawrence, Scott L.

1991-01-01

309

Visual and postural motion aftereffects following parabolic flight  

NASA Technical Reports Server (NTRS)

Postural and visual motion aftereffects may be experienced after exposure to alternating periods of free fall and increased gravitoinertial force in parabolic flight. In an aftereffect, the body feels as if it is again undergoing periodic changes in force level because of motion of the substrate; strong apparent postural motion is also accompanied by visual motion of the surroundings. The aftereffects are discussed according to: (1) their character, (2) their time course, (3) secondary symptoms associated with them, (4) conditions favoring their occurrence, (5) their relation to the inducing frequency, (6) fragments of the complete pattern, (7) their duration, and (8) the importance of contact cues.

Lackner, J. R.; Graybiel, A.

1980-01-01

310

4-E (energyexergyenvironmentaleconomic) analyses of line-focusing stand-alone concentrating solar power plants  

Microsoft Academic Search

In this study, energyexergyenvironmentaleconomic (4-E) analyses of stand-alone line-focusing concentrating solar power plants are carried out for different plant capacities ranging from 1 to 50 MWe<\\/sub>. Solar power plants based on concentrating power technologies are used to harness the solar radiation effectively. Among the solar power technologies, line-focusing concentrating systems such as linear Fresnel reflector (LFR) and parabolic trough collector

K. Ravi Kumar; K. S. Reddy

2012-01-01

311

Second law analysis and optimization of a parabolic trough receiver tube for direct steam generation  

NASA Astrophysics Data System (ADS)

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.

Nolte, H. C.; Bello-Ochende, T.; Meyer, J. P.

2014-12-01

312

Solar thermal electricity generation  

NASA Astrophysics Data System (ADS)

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.

Gasemagha, Khairy Ramadan

1993-01-01

313

Efficient solar-pumped Nd:YAG laser by a double-stage light-guide\\/V-groove cavity  

Microsoft Academic Search

Since the first reported Nd:YAG solar laser, researchers have been exploiting parabolic mirrors and heliostats for enhancing laser output performance. We are now investigating the production of an efficient solar-pumped laser for the reduction of magnesium from magnesium oxide, which could be an alternative solution to fossil fuel. Therefore both high conversion efficiency and excellent beam quality are imperative. By

Joana Almeida; Dawei Liang

2011-01-01

314

Performance and design optimization of a low-cost solar organic Rankine cycle for remote power generation  

Microsoft Academic Search

Recent interest in small-scale solar thermal combined heat and power (CHP) power systems has coincided with demand growth for distributed electricity supplies in areas poorly served by centralized power stations. One potential technical approach to meeting this demand is the parabolic trough solar thermal collector coupled with an organic Rankine cycle (ORC) heat engine.The paper describes the design of a

S. Quoilin; M. Orosz; H. Hemond; V. Lemort

2011-01-01

315

Mechanisms underlying modulations of thermal nystagmic responses in parabolic flight.  

PubMed

In six subjects nystagmography was used to compare the responses to cold calorization of one horizontal semicircular canal under ground-based and parabolic flight conditions. On the ground the expected individual differences in primary nystagmic responses were observed; only one subject manifested a brief weak secondary nystagmus. Aloft, the irrigation was carried out in straight-and-level flight prior to a pushover (half-parabola) that initiated a series of four to nine typical parabolas in a modified KC-135 aircraft. Thereafter, the free-fall phases of the parabolas furnished a zero baseline for measuring weight differences in endolymph due to changes in gravitoinertial force. In all subjects a secondary nystagmus was generated in addition to the primary nystagmus during the course of the parabolic maneuvers. The slow phase of the secondary nystagmus rarely exceeded 10 mm per sec. Evidence is presented that secondary nystagmus arises as a direction-specific adaptation effect countering the primary nystagmic response. Three stages were recognizable: first, when primary and secondary nystagmus alternated in step with the high and low force phases of the parabolas; second, after disappearance of primary nystagmus when secondary nystagmus appeared alone and was modulated by the changes in force; and third, when the secondary nystagmus present became independent of the highest gravitoinertial forces generated. Great individual differences were observed, suggesting that with large departures of the cupula from its functional rest position there are large individual variations in rate of restoration. PMID:6272537

Graybiel, A; O'Donnell, R D; Fluur, E; Nagaba, M; Smith, M J

1981-01-01

316

Non-Parabolic Hydrodynamic Formulations for the Simulation of Inhomogeneous Semiconductor Devices  

NASA Technical Reports Server (NTRS)

Hydrodynamic models are becoming prevalent design tools for small scale devices and other devices in which high energy effects can dominate transport. Most current hydrodynamic models use a parabolic band approximation to obtain fairly simple conservation equations. Interest in accounting for band structure effects in hydrodynamic device simulation has begun to grow since parabolic models cannot fully describe the transport in state of the art devices due to the distribution populating non-parabolic states within the band. This paper presents two different non-parabolic formulations or the hydrodynamic model suitable for the simulation of inhomogeneous semiconductor devices. The first formulation uses the Kane dispersion relationship ((hk)(exp 2)/2m = W(1 + alphaW). The second formulation makes use of a power law ((hk)(exp 2)/2m = xW(exp y)) for the dispersion relation. Hydrodynamic models which use the first formulation rely on the binomial expansion to obtain moment equations with closed form coefficients. This limits the energy range over which the model is valid. The power law formulation readily produces closed form coefficients similar to those obtained using the parabolic band approximation. However, the fitting parameters (x,y) are only valid over a limited energy range. The physical significance of the band non-parabolicity is discussed as well as the advantages/disadvantages and approximations of the two non-parabolic models. A companion paper describes device simulations based on the three dispersion relationships; parabolic, Kane dispersion and power law dispersion.

Smith, A. W.; Brennan, K. F.

1996-01-01

317

Non-parabolic hydrodynamic formulations for the simulation of inhomogeneous semiconductor devices  

NASA Technical Reports Server (NTRS)

Hydrodynamic models are becoming prevalent design tools for small scale devices and other devices in which high energy effects can dominate transport. Most current hydrodynamic models use a parabolic band approximation to obtain fairly simple conservation equations. Interest in accounting for band structure effects in hydrodynamic device simulation has begun to grow since parabolic models can not fully describe the transport in state of the art devices due to the distribution populating non-parabolic states within the band. This paper presents two different non-parabolic formulations of the hydrodynamic model suitable for the simulation of inhomogeneous semiconductor devices. The first formulation uses the Kane dispersion relationship (hk)(exp 2)/2m = W(1 + alpha(W)). The second formulation makes use of a power law ((hk)(exp 2)/2m = xW(sup y)) for the dispersion relation. Hydrodynamic models which use the first formulation rely on the binomial expansion to obtain moment equations with closed form coefficients. This limits the energy range over which the model is valid. The power law formulation readily produces closed form coefficients similar to those obtained using the parabolic band approximation. However, the fitting parameters (x,y) are only valid over a limited energy range. The physical significance of the band non-parabolicity is discussed as well as the advantages/disadvantages and approximations of the two non-parabolic models. A companion paper describes device simulations based on the three dispersion relationships: parabolic, Kane dispersion, and power low dispersion.

Smith, Arlynn W.; Brennan, Kevin F.

1995-01-01

318

PARABOLIC INDUCTION AND JACQUET MODULES OF REPRESENTATIONS OF O(2n, F)  

E-print Network

PARABOLIC INDUCTION AND JACQUET MODULES OF REPRESENTATIONS OF O(2n, F) DUBRAVKA BAN Abstract. The multiplication is defined in terms of par- abolic induction, and the comultiplicitation in terms of Jacquet parabolic induction, and the comultiplication by Jacquet modules (see the third section of this paper

Ban, Dubravka

319

SIMULTANEOUS VS. NON-SIMULTANEOUS BLOW-UP IN NUMERICAL APPROXIMATIONS OF A PARABOLIC SYSTEM  

E-print Network

SIMULTANEOUS VS. NON-SIMULTANEOUS BLOW-UP IN NUMERICAL APPROXIMATIONS OF A PARABOLIC SYSTEM) L ) = +. The blow-up phenomenon for parabolic equations and systems has been widely studied = u, vt = v in ? (0, T); fully coupled by the boundary conditions u = up11 vp12 , v = up21 vp22

Bonder, Julián Fernández

320

Non-simultaneous blow-up for a quasilinear parabolic system with reaction  

E-print Network

Non-simultaneous blow-up for a quasilinear parabolic system with reaction appearing in the system for which non-simultaneous blow-up indeed occurs. Moreover, we obtain the blow-up. Keywords and phrases: blow-up, parabolic systems, nonlinear diffusion, nonlin* *ear boundary conditions

Rossi, Julio D.

321

SIMULTANEOUS VS. NON-SIMULTANEOUS BLOW-UP IN NUMERICAL APPROXIMATIONS OF A PARABOLIC SYSTEM  

E-print Network

SIMULTANEOUS VS. NON-SIMULTANEOUS BLOW-UP IN NUMERICAL APPROXIMATIONS OF A PARABOLIC SYSTEM that lim sup t T ( u(·, t) L + v(·, t) L ) = +. The blow-up phenomenon for parabolic equations and systems = u, vt = v in ? (0, T); fully coupled by the boundary conditions u = up11 vp12 , v = up21 vp22

Groisman, Pablo

322

Non-simultaneous blow-up for a quasilinear parabolic system with reaction  

E-print Network

Non-simultaneous blow-up for a quasilinear parabolic system with reaction at the boundary Cristina in the system for which non-simultaneous blow-up indeed occurs. Moreover, we obtain the blow-up rate, 35K65, 35K55. Keywords and phrases: blow-up, parabolic systems, nonlinear diffusion, nonlinear

Quirós, Fernando

323

BACOL: B-Spline Adaptive COLlocation Software for 1-D Parabolic PDEs  

E-print Network

and temporal error estimates. The software implements a spline collocation method at Gaussian points, with a B-splineBACOL: B-Spline Adaptive COLlocation Software for 1-D Parabolic PDEs R. WANG and P. KEAST Dalhousie, Performance Additional Key Words and Phrases: 1-D Parabolic PDEs, B-splines, collocation, high

Keast, Patrick

324

IMPLICIT SPACE-TIME DOMAIN DECOMPOSITION METHODS FOR STOCHASTIC PARABOLIC PARTIAL DIFFERENTIAL  

E-print Network

-parallel methods to solve systems of ordinary differential equations (ODEs) with initial condition. In this methodIMPLICIT SPACE-TIME DOMAIN DECOMPOSITION METHODS FOR STOCHASTIC PARABOLIC PARTIAL DIFFERENTIAL-time domain decomposition methods for solv- ing deterministic and stochastic parabolic equations. Traditional

Cai, Xiao-Chuan

325

Parabolic and white-noise approximations for elastic waves in random media  

E-print Network

Parabolic and white-noise approximations for elastic waves in random media Josselin Garnier equations in random media in the parabolic white-noise regime. In this regime, the propagation distance are rapid and can be approximated by a white-noise term. The main motivations for studying the white-noise

Solna, Knut

326

Parabolic equation solution of seismo-acoustics problems involving variations in bathymetry and sediment thickness  

E-print Network

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 equation J. Acoust. Soc. Am. 120, 3534­3538 2006 handles a sloping fluid-solid interface at the ocean

327

Preliminary assessment of solar organic Rankine cycles for driving a desalination system  

Microsoft Academic Search

A detailed analysis of low power (100 kW) solar-driven Rankine cycles in the medium temperature range has been carried out. Toluene, octamethylcyclotetrasiloxane (D4) and hexamethyldisiloxane (MM) has been considered as working fluids of organic Rankine cycle (ORC). Direct solar vapor generation configuration of solar ORC has been analysed and characterized with LS3 and IND300 parabolic trough collector (PTC) models. The

Agustn M. Delgado-Torres; Lourdes Garca-Rodrguez

2007-01-01

328

Homogeneus ferrioxalate-assisted solar photo-Fenton degradation of Orange II aqueous solutions  

Microsoft Academic Search

The decoloration and mineralization of the non-biodegradable azo dye Orange II (OII) solutions by solar photo-Fenton (SPF) and ferrioxalate-assisted solar photo-Fenton (SPFox) reactions have been carried out in a solar compound parabolic collector (CPC). A comparative study of these two processes was done by using multivariate experimental design including the following variables: pH and initial concentrations of Fe(II), oxalic acid,

J. M. Monteagudo; A. Durn; C. Lpez-Almodvar

2008-01-01

329

Simulation and operation of a solar powered organic Rankine cycle turbine  

Microsoft Academic Search

Sandia Laboratories' ERDA-sponsored Solar Total Energy System Test Facility utilizes 814 sq m (8759 sq ft) of solar tracking, east-west oriented, parabolic trough collectors to heat Therminol 66 heat transfer fluid to 316 C (600 F). The energy is stored as sensible heat in a 5246 gal storage tank. The solar-heated fluid is then used to power an organic Rankine

A. F. Veneruso

1976-01-01

330

Short duration microgravity experiments in physical and life sciences during parabolic flights: the first 30 ESA campaigns  

Microsoft Academic Search

Aircraft parabolic flights provide repetitively up to 20s of reduced gravity during ballistic flight manoeuvres. Parabolic flights are used to conduct short microgravity investigations in Physical and Life Sciences, to test instrumentation and to train astronauts before a space flight. The European Space Agency (ESA) has organized since 1984 thirty parabolic flight campaigns for microgravity research experiments utilizing six different

Vladimir Pletser

2004-01-01

331

Protective telescoping shield for solar concentrator  

NASA Technical Reports Server (NTRS)

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.

Argoud, M. J.; Walker, W. L.; Butler, L. V. (inventors)

1986-01-01

332

Solar astronomy  

NASA Technical Reports Server (NTRS)

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.

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

333

Investigation of reliability attributes and accelerated stress factors on terrestrial solar cells  

NASA Technical Reports Server (NTRS)

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.

Lathrop, J. W.

1982-01-01

334

Optimal Control of a Parabolic Equation with Dynamic Boundary Condition  

SciTech Connect

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.

Hoemberg, D., E-mail: hoemberg@wias-berlin.de; Krumbiegel, K., E-mail: krumbieg@wias-berlin.de [Weierstrass Institute for Applied Mathematics and Stochastics, Nonlinear Optimization and Inverse Problems (Germany); Rehberg, J., E-mail: rehberg@wias-berlin.de [Weierstrass Institute for Applied Mathematics and Stochastics, Partial Differential Equations (Germany)

2013-02-15

335

Parabolic equation modelling of backscatter from the rough sea surface  

NASA Astrophysics Data System (ADS)

A physically based numerical method is presented for calculating sea clutter at low grazing angles for microwave frequencies. Sea clutter is modeled as a two scale phenomenon: at low grazing angles, the backscattered energy is generated by ripples on the sea surface. A first order perturbation method gives the backscatter from a small patch of surface, as a function of the angle of incidence and of the magnitude of the incident field. Returns from a clutter cell are obtained by incoherent summation of these echoes. Shadowing and tilting effects due to the larger scale components of the sea surface are modeled using a finite difference implementation of the parabolic equation method, which also deals with atmospheric refraction effects. Realizations of the sea surface with the desired spectral characteristics are generated with a Monte Carlo method. Results are presented at S band and X band for a variety of propagation conditions.

Levy, M. F.

1991-09-01

336

Flight Analysis of a Parabolic Lightcraft-Ground-based Launch  

SciTech Connect

An experimental environment has been developed for free flight experiments with a parabolic lightcraft in a laboratory scale. An electron beam sustained CO{sub 2} laser is employed as source for energy beaming with 10.6 {mu}m wavelength, {approx}10 {mu}s pulse duration, pulse energies up to 200 J and repetition rates up to 40 Hz. The free flight range of 1.7 meters enables to monitor several subsequent pulses in one flight as well as, in the case of Delrin (POM) as a propellant, a single pulse with a large momentum transfer. The impulse coupling is derived from flight trajectories and analyzed with respect to the temporal course of the flight. The influence of beam-related parameters like pulse energy and repetition rate are discussed regarding the flight performance. Finally, an insight is given into actual work on the transformation of the testbed for flights in vacuum.

Scharring, Stefan; Eckel, Hans-Albert [Institute of Technical Physics, German Aerospace Center, D-70569 Stuttgart, Pfaffenwaldring 38-40 (Germany); Roeser, Hans-Peter [Institute of Space Systems, University of Stuttgart, D-70569 Stuttgart, Pfaffenwaldring 31 (Germany)

2008-04-28

337

Large Phased Array Radar Using Networked Small Parabolic Reflectors  

NASA Technical Reports Server (NTRS)

Multifunction phased array systems with radar, telecom, and imaging applications have already been established for flat plate phased arrays of dipoles, or waveguides. In this paper the design trades and candidate options for combining the radar and telecom functions of the Deep Space Network (DSN) into a single large transmit array of small parabolic reflectors will be discussed. In particular the effect of combing the radar and telecom functions on the sizes of individual antenna apertures and the corresponding spacing between the antenna elements of the array will be analyzed. A heterogeneous architecture for the DSN large transmit array is proposed to meet the radar and telecom requirements while considering the budget, scheduling, and strategic planning constrains.

Amoozegar, Farid

2006-01-01

338

Generation of entangled matter qubits in two opposing parabolic mirrors  

E-print Network

We propose a scheme for the remote preparation of entangled matter qubits in free space. For this purpose, a setup of two opposing parabolic mirrors is considered, each one with a single ion trapped at its focus. To get the required entanglement in this extreme multimode scenario, we take advantage of the spontaneous decay, which is usually considered as an apparent nuisance. Using semiclassical methods, we derive an efficient photon-path representation to deal with this problem. We also present a thorough examination of the experimental feasibility of the scheme. The vulnerabilities arising in realistic implementations reduce the success probability, but leave the fidelity of the generated state unaltered. Our proposal thus allows for the generation of high-fidelity entangled matter qubits with high rate.

N. Trautmann; J. Z. Bernd; M. Sondermann; G. Alber; L. L. Snchez-Soto; G. Leuchs

2014-12-11

339

Gravitational wave energy spectrum of a parabolic encounter  

SciTech Connect

We derive an analytic expression for the energy spectrum of gravitational waves from a parabolic Keplerian binary by taking the limit of the Peters and Mathews spectrum for eccentric orbits. This demonstrates that the location of the peak of the energy spectrum depends primarily on the orbital periapse rather than the eccentricity. We compare this weak-field result to strong-field calculations and find it is reasonably accurate ({approx}10%) provided that the azimuthal and radial orbital frequencies do not differ by more than {approx}10%. For equatorial orbits in the Kerr spacetime, this corresponds to periapse radii of r{sub p} > or approx. 20M. These results can be used to model radiation bursts from compact objects on highly eccentric orbits about massive black holes in the local Universe, which could be detected by the Laser Interferometer Space Antenna (LISA).

Berry, Christopher P. L.; Gair, Jonathan R. [Institute of Astronomy, Madingley Road, Cambridge, CB3 0HA (United Kingdom)

2010-11-15

340

Generation of entangled matter qubits in two opposing parabolic mirrors  

NASA Astrophysics Data System (ADS)

We propose a scheme for the remote preparation of entangled matter qubits in free space. For this purpose, a setup of two opposing parabolic mirrors is considered, each one with a single ion trapped at its focus. To get the required entanglement in this extreme multimode scenario, we take advantage of the spontaneous decay, which is usually considered as an apparent nuisance. Using semiclassical methods, we derive an efficient photon-path representation to deal with this problem. We also present a thorough examination of the experimental feasibility of the scheme. The vulnerabilities arising in realistic implementations reduce the success probability, but leave the fidelity of the generated state unaltered. Our proposal thus allows for the generation of high-fidelity entangled matter qubits with high rate.

Trautmann, N.; Bernd, J. Z.; Sondermann, M.; Alber, G.; Snchez-Soto, L. L.; Leuchs, G.

2014-12-01

341

Initial conditions for parabolic calculation of reacting flows  

NASA Astrophysics Data System (ADS)

A parabolic combustion code called CHARNAL was run for a variety of measured and estimated inlet boundary conditions. A parametric study was carried out to determine what compromises in accuracy would occur if estimated, rather than experimentally measured, inlet conditions were used and what values of the dissipation length scale would give the best results. The conclusions were that a dissipation length scale of approximately 0.03 gave the best results regardless of the type of inlet conditions used. Both subsonic and supersonic flow were examined and the effect of finite-rate versus equilibrium-chemistry calculations was briefly considered. No significant compromises in accuracy were found when estimated inlet boundary conditions were used.

Brown, E. F.; Rogers, R. C.

1985-07-01

342

Hyperbolic/parabolic development for the GIM-STAR code  

NASA Astrophysics Data System (ADS)

Flow fields in supersonic inlet configurations were computed using the eliptic GIM code on the STAR computer. Spillage flow under the lower cowl was calculated to be 33% of the incoming stream. The shock/boundary layer interaction on the upper propulsive surface was computed including separation. All shocks produced by the flow system were captured. Linearized block implicit (LBI) schemes were examined to determine their application to the GIM code. Pure explicit methods have stability limitations and fully implicit schemes are inherently inefficient; however, LBI schemes show promise as an effective compromise. A quasiparabolic version of the GIM code was developed using elastical parabolized Navier-Stokes methods combined with quasitime relaxation. This scheme is referred to as quasiparabolic although it applies equally well to hyperbolic supersonic inviscid flows. Second order windward differences are used in the marching coordinate and either explicit or linear block implicit time relaxation can be incorporated.

Spradley, L. W.; Stalnaker, J. F.; Ratliff, A. W.

1980-12-01

343

A nonlinear parabolic problem from combustion theory: attractors and stability  

NASA Astrophysics Data System (ADS)

A parabolic (convection-diffusion) problem in a half-line, arising when modeling the temperature profile of an adiabatic solid in radiation-driven combustion, is considered. Both the coefficient in the "convective" term (the velocity of the burning front) and the Neumann datum (the prescribed heat influx into the burning body) are nonlinearly related to the proper value of the solution at the boundary. In addition, the velocity is allowed to vanish below some threshold value. Under the main assumptions of "intensely irradiated boundary" and initial data that behave suitably as x?-?, it is proven that there exists a global attractor for the evolution semigroup associated with the problem. Furthermore, the stabilization of all solutions towards the equilibrium solution (a uniformly propagating front) is derived for a class of Neumann data, which are of some interest for applications.

Pierotti, Dario; Verri, Maurizio

344

Parabolic dish Stirling module development and test results  

SciTech Connect

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.

Washom, B.

1984-08-01

345

Explicit upwind algorithm for the parabolized Navier-Stokes equations  

NASA Technical Reports Server (NTRS)

A new explicit upwind algorithm based on Roe's flux-difference splitting (FDS) method has been developed for the three-dimensional Parabolized Navier-Stokes (PNS) equations. For three-dimensional flows, FDS's are determined separately for the two nonmarching directions and modified to account for the calculated shock angle in the crossflow plane. Second-order FDS is applied to the pressure and convection terms with the streamwise pressure gradient limited in the subsonic region to maintain a hyperbolic inviscid equation set. Second-order central differencing is obtained in the two-step algorithm for the shear and heat flux terms. The new algorithm is demonstrated for three laminar flow test cases: supersonic flow over a flat plate, hypersonic flow over a 15 deg ramp, and hypersonic flow past a 10 deg cone at a 24 deg angle of attack. The computed results agree well with experimental measurements.

Korte, John J.; Mcrae, D. Scott

1988-01-01

346

Impurity binding energies in quantum dots with parabolic confinement  

NASA Astrophysics Data System (ADS)

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.

Abramov, Arnold

2015-03-01

347

Three-dimensional rogue waves in nonstationary parabolic potentials  

SciTech Connect

Using symmetry analysis we systematically present a higher-dimensional similarity transformation reducing the (3+1)-dimensional inhomogeneous nonlinear Schroedinger (NLS) equation with variable coefficients and parabolic potential to the (1+1)-dimensional NLS equation with constant coefficients. This transformation allows us to relate certain class of localized exact solutions of the (3+1)-dimensional case to the variety of solutions of integrable NLS equation of the (1+1)-dimensional case. As an example, we illustrated our technique using two lowest-order rational solutions of the NLS equation as seeding functions to obtain rogue wavelike solutions localized in three dimensions that have complicated evolution in time including interactions between two time-dependent rogue wave solutions. The obtained three-dimensional rogue wavelike solutions may raise the possibility of relative experiments and potential applications in nonlinear optics and Bose-Einstein condensates.

Yan Zhenya [Key Laboratory of Mathematics Mechanization, Institute of Systems Science, AMSS, Chinese Academy of Sciences, Beijing 100080 (China); International Centre for Materials Physics, Chinese Academy of Sciences, Shenyang 110016 (China); Konotop, V. V. [Centro de Fisica Teorica e Computacional and Departamento de Fisica, Faculdade de Cienacias, Universidade de Lisboa, Lisboa 1649-003 (Portugal); Akhmediev, N. [Optical Sciences Group, Research School of Physics and Engineering, Institute of Advanced Studies, Australian National University, Canberra, Australian Capital Territory 0200 (Australia)

2010-09-15

348

Cerebral vasoconstriction precedes orthostatic intolerance after parabolic flight  

NASA Technical Reports Server (NTRS)

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).

Serrador, J. M.; Shoemaker, J. K.; Brown, T. E.; Kassam, M. S.; Bondar, R. L.; Schlegel, T. T.

2000-01-01

349

Nonlocal operators, parabolic-type equations, and ultrametric random walks  

SciTech Connect

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), 7581 (2009) [Tr. Mat. Inst. Steklova 265, 8289 (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), 4857 (2004) [Tr. Mat. Inst. Steklova 245, 5564 (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), 42394246 (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), 177189 (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), 164167 (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.

Chacn-Cortes, L. F., E-mail: fchaconc@math.cinvestav.edu.mx; Ziga-Galindo, W. A., E-mail: wazuniga@math.cinvestav.edu.mx [Centro de Investigacion y de Estudios Avanzados del I.P.N., Departamento de Matematicas, Av. Instituto Politecnico Nacional 2508, Col. San Pedro Zacatenco, Mexico D.F., C.P. 07360 (Mexico)

2013-11-15

350

Critical Solutions of Three Vortex Motion in the Parabolic Case  

E-print Network

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.

Lu Ting; Omar Knio; Denis Blackmore

2008-07-02

351

Warsaw Catalogue of cometary orbits: 119 near-parabolic comets  

NASA Astrophysics Data System (ADS)

Context. The dynamical evolution of near-parabolic comets strongly depends on the starting values of the orbital elements derived from the positional observations. In addition, when drawing conclusions about the origin of these objects, it is crucial to control the uncertainties of orbital elements at each stage of the dynamical evolution. Aims: I apply a completely homogeneous approach to determine the cometary orbits and their uncertainties. The resulting catalogue is suitable for the investigation of the origin and future of near-parabolic comets. Methods: First, osculating orbits were determined on the basis of positional data. Second, the dynamical calculations were performed backwards and forwards up to 250 au from the Sun to derive original and future barycentric orbits for each comet. In the present investigation of dynamical evolution, the numerical calculations for a given object start from the swarm of virtual comets constructed using the previously determined osculating (nominal) orbit. In this way, the uncertainties of orbital elements were derived at the end of numerical calculations. Results: Homogeneous sets of orbital elements for osculating, original and future orbits are given. The catalogue of 119 cometary orbits constitutes about 70 per cent of all the first class so-called Oort spike comets discovered during the period 1801-2010 and about 90 per cent of those discovered in 1951-2010, for which observations were completed at the end of 2013. Non-gravitational (NG) orbits are derived for 45 comets, including asymmetric NG solution for six of them. Additionally, the new method for cometary orbit-quality assessment is applied for all these objects. The catalogue is available at http://ssdp.cbk.waw.pl/LPCs and also at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/567/A126

Krlikowska, Ma?gorzata

2014-07-01

352

Cerebral vasoconstriction precedes orthostatic intolerance after parabolic flight.  

PubMed

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). PMID:11033215

Serrador, J M; Shoemaker, J K; Brown, T E; Kassam, M S; Bondar, R L; Schlegel, T T

2000-09-01

353

Simulation of optical pulse compression using parabolic pulse with linear chirp  

NASA Astrophysics Data System (ADS)

It is the key of realizing high speed, large capacity fiber information transmission that achieve ultrashort optical pulse by optical pulse compression. At present, the compression method that is achieving parabolic pulse with linear chirp and compensating the linear chirp is paid more attention. Based on the two schemes for the parabolic pulse with linear chirp by the normal dispersion decreasing fiber or the fiber amplifier with a normal dispersion, more study on the characteristics of the parabolic pulse with linear chirp in the different dispersion decreasing profiles (such as cosine, Gaussian, linear, exponential and hyperbolic) is showed; the results show that, for different dispersion decreasing profiles, the good linear chirp and parabolic shapes that are good for pulse compression can be generated. Moreover, a novel scheme for the parabolic pulse, which is achieved by a dispersion decreasing fiber amplifier with a normal dispersion, is presented. Numerical simulations show that, compared with the parabolic pulses generated in the normal dispersion decreasing fiber or the fiber amplifier, the parabolic pulse generated by the novel scheme has the better linear chirp and the more pulse energy; the gain has an obviously effect on the intensity and quality of the linear chirp, which is that the output pulse has a smaller pulse width and higher pulse power after the chirp is compensated.

Wang, Zun-zhi

2013-08-01

354

Parabolic flight induces changes in gene expression patterns in Arabidopsis thaliana.  

PubMed

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

Paul, Anna-Lisa; Manak, Michael S; Mayfield, John D; Reyes, Matthew F; Gurley, William B; Ferl, Robert J

2011-10-01

355

The performance investigation of surface plasmon resonance sensor having parabolic diffused optical layer  

NASA Astrophysics Data System (ADS)

Effect of a parabolic diffused optical layer on the sensitivity, detection accuracy and quality parameter of surface plasmon resonance sensor are theoretically studied. The reflectivity of parabolic diffused graded profile sensor is calculated using transfer-matrix-method. The obtained reflectivities of this sensor are compared with the reflectivity of a uniform profile surface plasmon resonance sensor. It is observed that the introduction of parabolic graded optical layer decrease the sensitivity of sensor but the same time it improve the detection accuracy and quality parameter of sensor.

Kumar, S.; Sharma, G.; Singh, V.

2014-12-01

356

Fractional parabolic differential and difference equations with the Dirichlet-Neumann condition  

NASA Astrophysics Data System (ADS)

The multidimensional fractional parabolic equation with the Dirichlet-Neumann condition is studied. Stability estimates for the solution of the initial-boundary value problem for this fractional parabolic equation are established. The stable difference schemes for this problem are presented. Stability estimates for the solution of the first order of accuracy difference scheme are obtained. A procedure of modified Gauss elimination method is applied for the solution of first and second order of accuracy difference schemes of one-dimensional fractional parabolic differential equations.

Ashyralyev, Allaberen; Emirov, Nazar; Cakir, Zafer

2012-08-01

357

Cassegrainian concentrator solar array exploratory development module  

NASA Technical Reports Server (NTRS)

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%.

Patterson, R. E.; Crabtree, W. L.

1982-01-01

358

Saved by the Sun  

NSDL National Science Digital Library

This activity features video segments from a 2007 PBS program on solar energy. Students follow a seven-step invention process to design, build, and test a solar cooker that will pasteurize water. In addition, they are asked to describe how transmission, absorption, and reflection are used in a solar cooker to heat water and to evaluate what variables contribute to a successful cooker.

Lockwood, Jeff; Teachers, Nova

359

Heat engine development for solar thermal power systems  

NASA Technical Reports Server (NTRS)

The parabolic dish solar collector systems for converting sunlight to electrical power through a heat engine will, require a small heat engine of high performance long lifetime to be competitive with conventional power systems. The most promising engine candidates are Stirling, high temperature Brayton, and combined cycle. Engines available in the current market today do not meet these requirements. The development of Stirling and high temperature Brayton for automotive applications was studied which utilizes much of the technology developed in this automotive program for solar power engines. The technical status of the engine candidates is reviewed and the components that may additional development to meet solar thermal system requirements are identified.

Pham, H. Q.; Jaffe, L. D.

1981-01-01

360

Development of mass-producible line-focus tracking concentrating solar collectors. Category 2. Control systems. Final report  

Microsoft Academic Search

The system design criteria and concept of a mass-producible modular electronic control system for solar industrial process heating installations are discussed. The control system consists of: the master controller; the weather tower, including a solar tracking angle reference; and overtemperature switch, group control box, tracker\\/controller, and drive motor for each group of single-axis tracking parabolic trough solar collectors. System automatic

Hickman

1984-01-01

361

Solar Thermal Electricity Generating System  

NASA Astrophysics Data System (ADS)

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 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 earths surface, which results in from 63,2 GW/m2 at the Sun to 1 kW/m2 at Earths surface. The higher the concentration, the higher the temperatures we can achieve when converting solar radiation into thermal energy

Mishra, Sambeet; Tripathy, Pratyasha

2012-08-01

362

Generalized Directional Gradients, Backward Stochastic Differential Equations and Mild Solutions of Semilinear Parabolic Equations  

SciTech Connect

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.

Fuhrman, Marco [Dipartimento di Matematica, Politecnico di Milano, piazza Leonardo da Vinci 32, 20133 Milano (Italy)], E-mail: marco.fuhrman@polimi.it; Tessitore, Gianmario [Dipartimento di Matematica, Universita di Parma, via d'Azeglio 85, 43100 Parma (Italy)], E-mail: gianmario.tessitore@unipr.it

2005-05-15

363

hal-00168404,version1-28Aug2007 Dirac concentrations in Lotka-Volterra parabolic PDEs  

E-print Network

hal-00168404,version1-28Aug2007 Dirac concentrations in Lotka-Volterra parabolic PDEs Beno are indeed possible. Key-Words: Integral parabolic equations, adaptive dynamics, asymptotic behavior, Dirac to the equations t n - n = n R x, I(t) , x Rd , t 0, n(t = 0) = n0 L1(Rd), n0 0, (1) Universit´e Pierre

364

A parabolic function to modify Thornthwaite estimates of potential evapotranspiration for the eastern United States  

USGS Publications Warehouse

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

McCabe, G.J., Jr.

1989-01-01

365

Stability in terms of two measures for a class of semilinear impulsive parabolic equations  

NASA Astrophysics Data System (ADS)

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.

Dvirnyj, Aleksandr I.; Slyn'ko, Vitalij I.

2013-04-01

366

Stability in terms of two measures for a class of semilinear impulsive parabolic equations  

SciTech Connect

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.

Dvirnyj, Aleksandr I; Slyn'ko, Vitalij I

2013-04-30

367

A calculation procedure for heat, mass and momentum transfer in three-dimensional parabolic flows  

Microsoft Academic Search

A general, numerical, marching procedure is presented for the calculation of the transport processes in three-dimensional flows characterised by the presence of one coordinate in which physical influences are exerted in only one direction. Such flows give rise to parabolic differential equations and so can be called three-dimensional parabolic flows. The procedure can be regarded as a boundary-layer method. provided

S. V. PATANKAR; D. B. SPALDING

1972-01-01

368

Lyapunov functions in barriers for parabolic equations and in stability problems with respect to "white noise"  

NASA Astrophysics Data System (ADS)

The Cauchy problem for a parabolic equation with a small parameter multiplying the highest derivatives is considered. The dynamical system corresponding to the limit equation of the first order has an asymptotically stable equilibrium. A Lyapunov function known in a neighborhood of this equilibrium is used to construct a barrier in the Cauchy problem for the original parabolic equation. This result is applied to study the dynamical system with respect to random perturbations of the "white noise" type.

Kalyakin, L. A.

2014-10-01

369

Non-Classical Shocks for Buckley-Leverett: Degenerate Pseudo-Parabolic Regularisation  

Microsoft Academic Search

We consider oil-water flow in porous media, with a dynamic capillary pressure relation. This leads to a pseudo-parabolic degenerate regularisation of the Buckley-Leverett (BL) equation. It is known that linear pseudo-parabolic regularisations of BL lead to shock solutions that do not satisfy the Oleinik condition. In this note we analyse the existence of travelling wave solutions that violate the Oleinik

C. M. Cuesta; C. J. van Duijn; I. S. Pop

2006-01-01

370

What happens to the human heart in space? - Parabolic flights provide some answers  

NASA Astrophysics Data System (ADS)

Aircraft parabolic flights provide up to 20 seconds of reduced gravity repeatedly during ballistic flight manoeuvres. They are used to conduct short microgravity investigations in the physical- and life-sciences, to test instrumentation and to train astronauts for forthcoming space flights. The real value of parabolic flights lies, however, in the verification tests that can be conducted prior to taking experiments into space, in order to improve their quality and success rate.

Aubert, Andr E.; Beckers, Frank; Verheyden, Bart; Plester, Vladimir

2004-08-01

371

Solar Power  

NSDL National Science Digital Library

Students learn about solar energy and how to calculate the amount of solar energy available at a given location and time of day on Earth. The importance of determining incoming solar energy for solar devices is discussed.

Integrated Teaching And Learning Program

372

Solar Lentigo  

MedlinePLUS

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 ...

373

Comparison of Parabolic Filtration Methods for 3D Filtered Back Projection in Pulsed EPR Imaging  

PubMed Central

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

Qiao, Zhiwei; Redler, Gage; Epel, Boris; Halpern, Howard J

2015-01-01

374

On the coupling of hyperbolic and parabolic systems: Analytical and numerical approach  

NASA Technical Reports Server (NTRS)

The coupling of hyperbolic and parabolic systems is discussed in a domain Omega divided into two distinct subdomains omega(+) and omega(-). The main concern is to find the proper interface conditions to be fulfilled at the surface separating the two domains. Next, they are used in the numerical approximation of the problem. The justification of the interface conditions is based on a singular perturbation analysis, i.e., the hyperbolic system is rendered parabolic by adding a small artifical viscosity. As this goes to zero, the coupled parabolic-parabolic problem degenerates into the original one, yielding some conditions at the interface. These are taken as interface conditions for the hyperbolic-parabolic problem. Actually, two alternative sets of interface conditions are discussed according to whether the regularization procedure is variational or nonvariational. It is shown how these conditions can be used in the frame of a numerical approximation to the given problem. Furthermore, a method of resolution is discussed which alternates the resolution of the hyperbolic problem within omega(-) and of the parabolic one within omega(+). The spectral collocation method is proposed, as an example of space discretization (different methods could be used as well); both explicit and implicit time-advancing schemes are considered. The present study is a preliminary step toward the analysis of the coupling between Euler and Navier-Stokes equations for compressible flows.

Gastaldi, Fabio; Quarteroni, Alfio

1988-01-01

375

Comparison of parabolic filtration methods for 3D filtered back projection in pulsed EPR imaging  

NASA Astrophysics Data System (ADS)

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.

Qiao, Zhiwei; Redler, Gage; Epel, Boris; Halpern, Howard J.

2014-11-01

376

Performance of Infinitely Wide Parabolic and Inclined Slider Bearings Lubricated with Couple Stress or Magnetic Fluids  

NASA Astrophysics Data System (ADS)

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.

Oladeinde, Mobolaji Humphrey; Akpobi, John Ajokpaoghene

2011-10-01

377

Rankline-Brayton engine powered solar thermal aircraft  

DOEpatents

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.

Bennett, Charles L. (Livermore, CA)

2012-03-13

378

Rankine-Brayton engine powered solar thermal aircraft  

DOEpatents

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.

Bennett, Charles L. (Livermore, CA)

2009-12-29

379

Development of 2.8-GHz Solar Flux Receivers  

NASA Astrophysics Data System (ADS)

We report the development of solar flux receivers operating at 2.8 GHz to monitor solar radio activity. Radio waves from the sun are amplified, filtered, and then transmitted to a power meter sensor without frequency down-conversion. To measure solar flux, a calibration scheme is designed with a noise source, an ambient load, and a hot load at 100 C. The receiver is attached to a 1.8 m parabolic antenna in Icheon, owned by National Radio Research Agency, and observation is being conducted during day time on a daily basis. We compare the solar fluxes measured for last seven months with solar fluxes obtained by DRAO in Penticton, Canada, and by the Hiraiso solar observatory in Japan, and finally establish equations to convert observed flux to the so-called Penticton flux with an accuracy better than 3.2 sfu.

Yun, Youngjoo; Park, Yong-Sun; Kim, Chang-Hee; Lee, Bangwon; Kim, Jung-Hoon; Yoo, Saeho; Lee, Chul-Hwan; Han, Jinwook; Kim, Young Yun

2014-12-01

380

DESIGN, DEVELOPMENT AND PERFORMANCE STUDIES OF EMBEDDED ELECTRONIC CONTROLLED ONE AXIS SOLAR TRACKING SYSTEM  

Microsoft Academic Search

An electronic embedded system controlled one axis automatic solar tracking system is designed and developed for parabolic trough collector employed for hot water generation. The electronic circuit diagram with detailed description and performance of the tracking system are presented. The position of Sun is successfully detected us- ing light dependent resistors, with an accuracy of 0.1. The accuracy is much

A. Valan Arasu; T. Sornakumar

381

Fundamental research on heat transfer performances of solar focusing and tracking collector  

Microsoft Academic Search

The components and performance of a focusing solar energy cylindrical collector system are described. The mirror is parabolic in cross section with a 50 mm focal distance and is 900 mm long. The absorbing pipe is made of copper and has a black oxidized surface which was lined with grooves to increase the absorption; the procedure for producing grooves is

Y. Mori; K. Hijikata; N. Himeno; W. Nakayama

1977-01-01

382

Conceptual design and analysis of a 100-MWe line focus solar central power plant. Test plan  

Microsoft Academic Search

Plans for a test program are presented whose objectives are: to verify the overall efficiency of a linear parabolic trough solar collector with varied receiver tube subsystem configurations; to compare surface temperatures, and efficiency values to derived values from an analytical model; and to identify the optimal receivr tube and annulus combination as determined by economical, optical, and thermal efficiency.

M. G. Semmens; A. Fong; G. J. Collaros; R. E. Dascher; R. E. Grassberger; D. B. Griego; T. F. Suteber

2008-01-01

383

Influence of refractive index and solar concentration on optical power absorption in slabs  

NASA Technical Reports Server (NTRS)

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.

Williams, M. D.

1988-01-01

384

Influence of refractive index and solar concentration on optical power absorption in slabs  

SciTech Connect

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.

Williams, M.D.

1988-07-01

385

Optimization of low temperature solar thermal electric generation with Organic Rankine Cycle in different areas  

Microsoft Academic Search

The presented low temperature solar thermal electric generation system mainly consists of compound parabolic concentrators (CPC) and the Organic Rankine Cycle (ORC) working with HCFC-123. A novel design is proposed to reduce heat transfer irreversibility between conduction oil and HCFC-123 in the heat exchangers while maintaining the stability of electricity output. Mathematical formulations are developed to study the heat transfer

Li Jing; Pei Gang; Ji Jie

2010-01-01

386

Analysis of low temperature solar thermal electric generation using regenerative Organic Rankine Cycle  

Microsoft Academic Search

The innovative configuration of low temperature solar thermal electric generation with regenerative Organic Rankine Cycle (ORC) is designed, mainly consisting of small concentration ratio compound parabolic concentrators (CPC) and the regenerative ORC. Advantages of the innovative configuration such as effectively reducing heat transfer irreversibility and permitting the use of thermal storage with phase change materials (PCMs) are outlined. The numerical

Gang Pei; Jing Li; Jie Ji

2010-01-01

387

Efficient solution of parabolic equations by Krylov approximation methods  

NASA Technical Reports Server (NTRS)

Numerical techniques for solving parabolic equations by the method of lines is addressed. The main motivation for the proposed approach is the possibility of exploiting a high degree of parallelism in a simple manner. The basic idea of the method is to approximate the action of the evolution operator on a given state vector by means of a projection process onto a Krylov subspace. Thus, the resulting approximation consists of applying an evolution operator of a very small dimension to a known vector which is, in turn, computed accurately by exploiting well-known rational approximations to the exponential. Because the rational approximation is only applied to a small matrix, the only operations required with the original large matrix are matrix-by-vector multiplications, and as a result the algorithm can easily be parallelized and vectorized. Some relevant approximation and stability issues are discussed. We present some numerical experiments with the method and compare its performance with a few explicit and implicit algorithms.

Gallopoulos, E.; Saad, Y.

1990-01-01

388

Parabolic heavy ion flow in the polar magnetosphere  

NASA Technical Reports Server (NTRS)

Recent observations by the Dynamics Explorer 1 satellite over the dayside polar cap magnetosphere have indicated downward flows of heavy ions such as O(+), O(2+), N(+), and N(2+) with flow velocities of the order 1 km/s (Lockwood et al., 1985). These downward flows were interpreted as the result of 'parabolic' flow of these heavy ionospheric ions from a source region associated with the polar cleft topside ionosphere. Here, a two-dimensional kinetic model is utilized to elicit features of the transport of very low energy O(+) ions from the cleft ionosphere. Bulk parameter (density, flux, thermal energies, etc.) distributions in the noon-midnight meridian plane illustrate the effects of varying convection electric fields and source energies. The results illustrate that, particularly under conditions of weak convection electric fields and weak ion heating in the cleft region, much of the intermediate altitude polar cap magnetosphere may be populated by downward flowing heavy ions. It is further shown how two-dimensional transport effects may alter the characteristic vertical profiles of densities and fluxes from ordinary profiles computed in one-dimensional steady-state models.

Horwitz, J. L.

1987-01-01

389

A comparison of adaptive software for 1D parabolic PDEs  

NASA Astrophysics Data System (ADS)

In this paper we describe BACOL, a high-order, spatially and temporally adaptive software package for solving systems of one-dimensional parabolic partial differential equations and then compare it with several related software packages. BACOL employs collocation at Gaussian points with a B-spline basis for the spatial discretization. A modification of DASSL is used for the time integration of the resulting differential-algebraic equations. An equidistribution principle is implemented for the spatial mesh adaptation based on a high-quality a posteriori error estimate, and the spatial error tolerance is coupled with the temporal error tolerance to provide a balanced spatial-temporal error control. We compare BACOL with a related software package, EPDCOL, which uses a fixed-spatial-mesh approach, with several other packages which provide spatial and temporal adaptivity, namely D03PPF, TOMS731, MOVCOL, and with one package, HPNEW, which provides spatial and temporal error control. Numerical results demonstrate that BACOL is robust and that it is generally significantly more efficient than existing solvers for problems having solutions with rapid spatial variation.

Wang, Rong; Keast, Patrick; Muir, Paul

2004-08-01

390

Friction of spheres on a rotating parabolic support  

E-print Network

This article illustrates the role of friction on the motion of a rolling sphere on pedagogical example. We use a parabolic support rotating around it axis to study the static equilibrium positions of a single sphere. Due to the particular choice of the shape of support, some easy analytical calculations allow theoretical predictions. (i) In the frictionless case, there is an eigen frequency of rotation where the gravity balances the centrifugal force. All positions on the parabola are therefore in static equilibrium. At others rates of rotation, the sphere can go to the center or escape to infinity. It depends only on the sign of the detuning with the eigenfrequency. (ii) In contrast, we show that the static friction imposes a range of equilibrium positions at all rotating rates. These predictions can be compared to the maximum equilibrium radius measured on the experimental device. A reasonable estimate of the static friction between the support and spheres made of different materials can be extracted from t...

Soulier, Alexis

2014-01-01

391

Conservation Laws and Potential Symmetries of Linear Parabolic Equations  

E-print Network

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.

Roman O. Popovych; Michael Kunzinger; Nataliya M. Ivanova

2007-06-04

392

Experimental natural convective studies within a compound parabolic concentrator enclosure  

SciTech Connect

The contribution due to natural convection within a compound parabolic concentrator enclosure has been experimentally determined. These studies have been conducted within a 4X-CPC collector, having a receiver width of 3.175 cm (1.25 inches) and 2.44 m (96 inches) in length. The receiver was heated electrically while the aperture was provided with a duct that was cooled by water. The limbs of the collector were fabricated from aluminum. Temperatures were directly obtained with copper-constantan thermocouples located throughout the entire enclosure and provided the basis needed to calculate the different modes of heat transfer. The constant heat flux at the receiver translated to a nearly isothermal state. The rates of natural convection have been expressed in terms of a Nu-Ra correlation where 1.0x10/sup 7/ < Ra < 4.0x10/sup 7/. To suppress natural convection, a horizontal partition was introduced at different heights between the receiver and aperture. These results have been expressed as heat fluxes and temperature differences between the receiver and the aperture. This information made possible a comparison between the aperture-partition enclosure and a flat plate geometry.

Tatara, R.A.; Thodos, G.

1983-01-01

393

An anisotropic model of diffuse solar radiation with application to an optimization of compound parabolic collectors  

Microsoft Academic Search

Based on a simple geometrical description of the sky hemisphere and the magnitude of the horizontal diffuse radiation, a model for estimating diffuse radiation impinging on sloping surfaces was developed. Tests against data show that substantial improvement is achieved over the classical isotropic model for any collector slope or orientation. Improvement is found for instantaneous as well as accumulated data.

R. R. Perez

1983-01-01

394

The analysis of residual stress in glass-to-metal seals for solar receiver tube  

Microsoft Academic Search

The solar receiver tube is a key component in the parabolic trough solar thermal power system. Breakage of glass-to-metal sealing is main cause for damages of receivers in existing power plants. The residual stresses that are generated during the cooling process of the seal can decrease the seal strength and induce the breakage of the glass-to-metal sealing. Residual stresses were

Dongqiang Lei; Zhifeng Wang; Jian Li

2010-01-01

395

Effect of stratospheric aerosols on direct sunlight and implications for concentrating solar power.  

PubMed

Light scattering calculations and data show that stratospheric aerosols reduce direct sunlight by about 4 W for every watt reflected to outer space. The balance becomes diffuse sunlight. One consequence of deliberate enhancement of the stratospheric aerosol layer would be a significant reduction in the efficiency of solar power generation systems using parabolic or other concentrating optics. There also would be a reduction in the effectiveness of passive solar design. PMID:19475950

Murphy, Daniel M

2009-04-15

396

Flux density distribution in the focal region of a solar concentrator system  

Microsoft Academic Search

In high temperature solar energy applications highly concentration optical systems, such as, e.g., parabolic dishes, achieve typical tradition flux densities <2 MW\\/M². In order to investigate thermo and photochemical reactions at temperatures <1500 K and radiation flux densities <2 MW\\/m² a solar furnace was built at Paul Scherrer Institute (PSI). This furnace is a two-stage concentrator. The first stage is

M. Schubnell; J. Keller; A. Imhof

1991-01-01

397

Photocatalytic degradation of oxytetracycline using TiO 2 under natural and simulated solar radiation  

Microsoft Academic Search

The main objective of the present study was to assess the photocatalytic degradation over TiO2 of an aqueous solution containing 20mgL?1 of the antibiotic Oxytetracycline (OTC) using simulated solar radiation, seconded by a solar radiation experiment carried out in a pilot plant equipped with Compound Parabolic Collectors (CPCs) under the optimal conditions found in preliminary lab-scale experiments. These comprehended a

Joo H. O. S. Pereira; Vtor J. P. Vilar; Maria T. Borges; Oscar Gonzlez; Santiago Esplugas; Rui A. R. Boaventura

2011-01-01

398

Solar production of industrial process steam for the Lone Star Brewery. 80% review report  

Microsoft Academic Search

The solar steam system for the Lone Star Brewery is described in detail. It consists of a roof-mounted parabolic trough collector field heating Monsanto's Therminol T-55 heat transfer fluid, a solar-fired boiler, a heat transfer fluid circulation pump, and all the associated piping. The comparison of various collectors and heat transfer fluids surveyed is reviewed. Also included are discussions of

D. M. Deffenbaugh; P. V. Watkins; S. B. Hugg; J. J. Kulesz; H. E. Decker; R. C. Powell

1979-01-01

399

Optimized concentrating\\/passive tracking solar collector. Final report  

Microsoft Academic Search

A concentrating solar collector having abut half the material cost of other collectors with similar performance was developed and tested. The selected design is a Compound Parabolic Concentrator (CPC). Output is a fluid heated to 100°C with good efficiency. The optical design of the reflector surface was optimized, yielding a 2.0:1 concentration with a 60° acceptance angle and a low

K. E. Sterne; A. L. Johnson; R. H. Grotheer

1979-01-01

400

High-concentration photovoltaic designs based on miniature parabolic dishes  

NASA Astrophysics Data System (ADS)

A new approach for concentrating photovoltaic systems that can easily attain the maximum flux levels commensurate with solar cell technology is proposed. The collection unit is a miniature paraboloidal dish which concentrates sunlight into a short glass rod. The flux distribution of the transported light is homogenized in a miniature glass kaleidoscope that is optically coupled to a small high-efficiency solar cell. The cell resides behind the dish and can be cooled adequately with a passive heat sink. These nominally independent collection units can be assembled into modules and arrays that produce almost any prescribed power level. All system elements are predicated on existing technologies.

Feuermann, Daniel; Gordon, Jeffrey M.

2001-11-01

401

Cluster eye camera using microlenses on parabolic surface  

NASA Astrophysics Data System (ADS)

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.

Shen, Hui-Kai; Su, Guo-Dung J.

2013-10-01

402

Feasibility of an iodine gas laser pumped by concentrated terrestrial solar radiation  

SciTech Connect

A t-C{sub 4}F{sub 9}I iodine gas laser pumped by terrestrial sunlight was analyzed. Lasant properties, spectral terrestrial insolation data, and established laser fundamentals were used to develop a mathematical model of a terrestrial solar-pumped system. Threshold pumping power and available terrestrial pumping power were predicted and used to estimate the solar concentration required to initiate lasing. Laser output power was also predicted. Because this lasant is relatively new and has never been pumped by solar radiation, many physical properties are not well known. An uncertainty analysis was used to predict errors in threshold solar concentration and output power. In all cases, conservative estimates of physical properties were used. The dominant uncertainty in both threshold and output predictions was due to wide variation in published values of the quenching reaction caused by the lasant parent molecule. Several optical and geometric configurations were devised using commercially available primary solar collectors: parabolic or compound parabolic troughs, a Shenandoah-type 7.5 meter diameter parabolic dishes, or a 17 meter diameter stretched membrane dish. Threshold solar concentration for these systems ranged from below 50 to almost 200 suns depending on the laser tube geometry. Output power ranged from below 1 Watt to almost 90 Watts, and was a function of primary collector dimension.

Terry, C.K.; Peterson, J.E.; Goswami, D.Y. [Univ. of Florida, Gainesville, FL (United States). Dept. of Mechanical Engineering

1995-11-01

403

Solar receiver with integrated optics  

NASA Astrophysics Data System (ADS)

The current challenge for PV/Thermal (PV/T) systems is the reduction of radiation heat loss. Compared to solar thermal selective coating, the solar cells cannot be used as an efficient thermal absorber due to their large emissivity of the encapsulation material. Many commercial PV/T products therefore require a high concentration (more than 10x) to reach an acceptable thermal efficiency for their receivers. Such a concentration system inevitably has to track or semi-track, which induces additional cost and collects only the direct radiation from the sun. We propose a new PV/T design using a vacuum encapsulated thin film cell to solve this problem. The proposed design also collects the diffuse sun light efficiently by using an external compound parabolic concentrator (XCPC). Since the transparent electrode (TCO) of thin film cell is inherently transparent in visible light and reflective beyond infrared, this design uses this layer instead of the conventional solar cell encapsulation as the outmost heat loss surface. By integrating such a vacuum design with a tube shaped absorber, we reduce the complexity of conducting the heat energy and electricity out of the device. A low concentration standalone non-tracking solar collector is proposed in this paper. We also analyzed the thermosyphon system configuration using heat transfer and ray tracing models. The economics of such a receiver are presented.

Jiang, Lun; Winston, Roland

2012-10-01

404

Siting Utility-Scale Concentrating Solar Power Projects  

SciTech Connect

In 2002, Congress asked the U.S. Department of Energy to develop and scope out an initiative to fulfill the goal of having 1,000 megawatts (MW) of new parabolic trough, power tower, and dish engine solar capacity supplying the southwestern United States. In this paper, we present a review of the solar resource for Arizona, California, Nevada, and New Mexico. These four states have the greatest number of ''premium'' solar sites in the country and each has a renewable portfolio standard (RPS). We present information on the generation potential of the solar resources in these states. We also present regions within New Mexico that may be ideally suited for developing large-scale concentrating solar power (CSP) plants because of their proximity to load and their access to unconstrained transmission.

Mehos, M.; Owens, B.

2005-01-01

405

Solar Thermal Concept Evaluation  

NASA Technical Reports Server (NTRS)

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.

Hawk, Clark W.; Bonometti, Joseph A.

1995-01-01

406

A note on the classical weak and strong maximum principles for linear parabolic partial differential inequalities  

NASA Astrophysics Data System (ADS)

In this note, we highlight a difference in the conditions of the classical weak maximum principle and the classical strong maximum principle for linear parabolic partial differential inequalities. We demonstrate, by the careful construction of a specific function, that the condition in the classical strong maximum principle on the coefficient of the zeroth-order term in the linear parabolic partial differential inequality cannot be relaxed to the corresponding condition in the classical weak maximum principle. In addition, we demonstrate that results (often referred to as boundary point lemmas) which conclude positivity of the outward directional derivatives of nontrivial solutions to linear parabolic partial differential inequalities at certain points on the boundary where a maxima is obtained cannot be obtained under the same zeroth-order coefficient conditions as in the classical strong maximum principle.

Needham, David John; Meyer, John Christopher

2015-01-01

407

Piecewise parabolic negative magnetoresistance of two-dimensional electron gas with triangular antidot lattice  

SciTech Connect

Extraordinary piecewise parabolic behavior of the magnetoresistance has been experimentally detected in the two-dimensional electron gas with a dense triangular lattice of antidots, where commensurability magnetoresistance oscillations are suppressed. The magnetic field range of 0-0.6 T can be divided into three wide regions, in each of which the magnetoresistance is described by parabolic dependences with high accuracy (comparable to the experimental accuracy) and the transition regions between adjacent regions are much narrower than the regions themselves. In the region corresponding to the weakest magnetic fields, the parabolic behavior becomes almost linear. The observed behavior is reproducible as the electron gas density changes, which results in a change in the resistance by more than an order of magnitude. Possible physical mechanisms responsible for the observed behavior, including so-called 'memory effects,' are discussed.

Budantsev, M. V., E-mail: budants@isp.nsc.ru; Lavrov, R. A.; Pogosov, A. G.; Zhdanov, E. Yu.; Pokhabov, D. A. [Russian Academy of Sciences, Rzhanov Institute of Semiconductor Physics, Siberian Branch (Russian Federation)

2011-02-15

408

Advanced solar concentrator mass production, operation, and maintenance cost assessment  

NASA Technical Reports Server (NTRS)

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.

Niemeyer, W. A.; Bedard, R. J.; Bell, D. M.

1981-01-01

409

Criteria for the evaluation of laser solar energy converter systems  

NASA Technical Reports Server (NTRS)

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.

Harries, W. L.

1985-01-01

410

Parabolic dune reactivation and migration at Napeague, NY, USA: Insights from aerial and GPR imagery  

NASA Astrophysics Data System (ADS)

Observations from mapping since the 19th century and aerial imagery since 1930 have been used to study changes in the aeolian geomorphology of coastal parabolic dunes over the last ~ 170 years in the Walking Dune Field, Napeague, NY. The five large parabolic dunes of the Walking Dune Field have all migrated across, or are presently interacting with, a variably forested area that has affected their migration, stabilization and morphology. This study has concentrated on a dune with a particularly complex history of stabilization, reactivation and migration. We have correlated that dune's surface evolution, as revealed by aerial imagery, with its internal structures imaged using 200 MHz and 500 MHz Ground Penetrating Radar (GPR) surveys. Both 2D (transect) and high-resolution 3D GPR imagery image downwind dipping bedding planes which can be grouped by apparent dip angle into several discrete packages of beds that reflect distinct decadal-scale episodes of dune reactivation and growth. From aerial and high resolution GPR imagery, we document a unique mode of reactivation and migration linked to upwind dune formation and parabolic dune interactions with forest trees. This study documents how dune-dune and dune-vegetation interactions have influenced a unique mode of blowout deposition that has alternated on a decadal scale between opposite sides of a parabolic dune during reactivation and migration. The pattern of recent parabolic dune reactivation and migration in the Walking Dune Field appears to be somewhat more complex, and perhaps more sensitive to subtle environmental pressures, than an idealized growth model with uniform deposition and purely on-axis migration. This pattern, believed to be prevalent among other parabolic dunes in the Walking Dune Field, may occur also in many other places where similar observational constraints are unavailable.

Girardi, James D.; Davis, Dan M.

2010-02-01

411

UPC BarcelonaTech Platform. Innovative aerobatic parabolic flights for life sciences experiments.  

NASA Astrophysics Data System (ADS)

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.

Perez-Poch, Antoni; Gonzalez, Daniel

412

Upper bounds for the yearly energy delivery of stationary solar concentrators and the implications for concentrator optical design  

Microsoft Academic Search

Compound parabolic concentrator (CPC) type collectors have been viewed as the optimal design for totally stationary concentrators. However the CPC is ideal only for uniform incident solar flux averaged over the energy collection period. The actual yearly-averaged incident flux map turns out to be highly non-uniform, as a function of projected incidence angle, which implies that concentration can be increased

J. M. Gordon; Michelle Lasken; Harald Ries

1996-01-01

413

Performance of staged solar thermal collector arrays for low and medium temperature applications  

SciTech Connect

Solar thermal energy systems for commercial and industrial applications often require heat over a temperature range appropriate for flat plate, evacuated tube, or parabolic trough collectors. Design optimization often considers performance and cost tradeoffs between the alternative collector designs. The use of a staged collector array, employing the different collector designs operating in series, is considered in this paper. A TRNSYS model of a staged collector array system is developed and simulation results of performance are provided and compared with arrays with single collector designs. Results show that a staged array employing equal areas of flat plate, evacuated tube, and parabolic trough collectors, can provide performance which exceeds or is competitive with an all parabolic trough array of equal total area. Daily performance profiles of the staged array illustrate the effectiveness of the staged design in providing useful operating temperatures to each collector type.

Breger, D.S. [Lafayette Coll., Easton, PA (United States). Dept. of Civil and Environmental Engineering

1996-11-01

414

Two-electron states and state exchange time control in parabolic quantum dot  

NASA Astrophysics Data System (ADS)

Using the Heisenberg uncertainty relationship and the stationary perturbation theory we consider two-electron states in a spherically symmetric parabolic quantum dot (parabolic helium atom). The dependence of ground-state energy on the QD size is studied. The energy of two-electron system monotonically decreases with QD radius increase. The problem of the state exchange time control in QD is discussed, taking into account the spins of the electrons in the Russell-Saunders approximation. With the increase of the QD radius the state exchange time increases.

Baghdasaryan, D. A.; Kazaryan, E. M.; Sarkisyan, H. A.

2014-04-01

415

New Integral Representations for Solutions of Cauchy's Problem for Abstract Parabolic Equations  

PubMed Central

A study has been made of Cauchy's problem for a class of abstract parabolic differential equations. Our study is based upon a transformation that maps solutions of second-order abstract Cauchy problems into solutions of first-order. This is a preliminary report on some of the results obtained. These results include (1) new representations for solutions of abstract parabolic equations, (2) applications to the heat equation, (3) a discussion of solution representations for second-order abstract Cauchy problems, and (4) applications to nonwell posed (in the sense of Hadamard) Cauchy problems. PMID:16591940

Donaldson, J. A.

1971-01-01

416

Parabolic replicator dynamics and the principle of minimum Tsallis information gain  

PubMed Central

Background Non-linear, parabolic (sub-exponential) and hyperbolic (super-exponential) models of prebiological evolution of molecular replicators have been proposed and extensively studied. The parabolic models appear to be the most realistic approximations of real-life replicator systems due primarily to product inhibition. Unlike the more traditional exponential models, the distribution of individual frequencies in an evolving parabolic population is not described by the Maximum Entropy (MaxEnt) Principle in its traditional form, whereby the distribution with the maximum Shannon entropy is chosen among all the distributions that are possible under the given constraints. We sought to identify a more general form of the MaxEnt principle that would be applicable to parabolic growth. Results We consider a model of a population that reproduces according to the parabolic growth law and show that the frequencies of individuals in the population minimize the Tsallis relative entropy (non-additive information gain) at each time moment. Next, we consider a model of a parabolically growing population that maintains a constant total size and provide an implicit solution for this system. We show that in this case, the frequencies of the individuals in the population also minimize the Tsallis information gain at each moment of the internal time of the population. Conclusions The results of this analysis show that the general MaxEnt principle is the underlying law for the evolution of a broad class of replicator systems including not only exponential but also parabolic and hyperbolic systems. The choice of the appropriate entropy (information) function depends on the growth dynamics of a particular class of systems. The Tsallis entropy is non-additive for independent subsystems, i.e. the information on the subsystems is insufficient to describe the system as a whole. In the context of prebiotic evolution, this non-reductionist nature of parabolic replicator systems might reflect the importance of group selection and competition between ensembles of cooperating replicators. Reviewers This article was reviewed by Viswanadham Sridhara (nominated by Claus Wilke), Puushottam Dixit (nominated by Sergei Maslov), and Nick Grishin. For the complete reviews, see the Reviewers Reports section. PMID:23937956

2013-01-01

417

Study of weak solutions for a fourth-order parabolic equation with variable exponent of nonlinearity  

NASA Astrophysics Data System (ADS)

The aim of this paper is to study the existence and uniqueness of weak solutions for an initial boundary problem of a fourth-order parabolic equation with variable exponent of nonlinearity. First, the authors of this paper apply Leray-Schauder's fixed point theorem to prove the existence of solutions of the corresponding nonlinear elliptic problem and then obtain the existence of weak solutions of nonlinear parabolic problem by combining the results of the elliptic problem with Rothe's method. In addition, the authors also discuss the regularity of weak solutions in the case of space dimension one.

Guo, Bin; Gao, Wenjie

2011-10-01

418

Wave-packet reconstruction via local dynamics in a parabolic lattice  

SciTech Connect

We study the dynamics of a wave packet in a potential formed by the sum of a periodic lattice and a parabolic potential. The dynamics of the wave packet is essentially a superposition of oscillations with frequencies proportional to the local slope of the parabolic potential. The amplitude and the phase of the Fourier transform of a signal characterizing this dynamics then contain information about the amplitude and the phase of the wave packet at a given lattice site. Hence, complete reconstruction of the wave packet in real space can be performed from a study of the dynamics of the system.

Thommen, Quentin; Zehnle, Veronique; Garreau, Jean Claude [Laboratoire de Physique des Lasers, Atomes et Molecules and Centre d'Etudes et de Recherches Laser et Applications, Universite des Sciences et Technologies de Lille, F-59655 Villeneuve d'Ascq Cedex (France)

2003-01-01

419

Generation and tooth contact analysis of spiral bevel gears with predesigned parabolic functions of transmission errors  

NASA Technical Reports Server (NTRS)

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.

Litvin, Faydor L.; Lee, Hong-Tao

1989-01-01

420

Transesophageal echocardiographic evaluation of baboons during microgravity induced by parabolic flight  

NASA Technical Reports Server (NTRS)

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.

Vernalis, Marina N.; Latham, Ricky D.; Fanton, John W.; Geffney, F. Andrew

1993-01-01

421

Well-Posedness of Nonlocal Parabolic Differential Problems with Dependent Operators  

PubMed Central

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 Hlder condition with a weight (t + ?)?. New Schauder type exact estimates in Hlder norms for the solution of two nonlocal boundary value problems for parabolic equations with dependent coefficients are established. PMID:24526903

Ashyralyev, Allaberen; Hanalyev, Asker

2014-01-01

422

Complete blow-up and avalanche formation for a parabolic system with non-simultaneous blow-up  

E-print Network

Complete blow-up and avalanche formation for a parabolic system with non-simultaneous blow-up a nontrivial continuation after the blow-up time for a system of two heat equations with a nonlinear coupling, 35K60, 35K57. Keywords and phrases: complete blow-up, parabolic system, nonlinear boundary conditions

Rossi, Julio D.

423

Performance of a monolithic catalytic converter used in automotive emission control: The effect of a longitudinal parabolic active metal distribution  

Microsoft Academic Search

The effect of a longitudinal parabolic active metal distribution on the performance of a monolithic converter is reported. On the basis of the results of numerical calculations, the improvement in the performance of the catalytic converter with parabolic axial active material distribution compared with the respective uniform distribution is verified. In addition, in cases where operating conditions fail to light-off

Apostolos Psyllos; Constantine Philippopoulos

1993-01-01

424

Quadratic spline collocation for onedimensional linear parabolic partial differential equations Christina C. Christara, Tong Chen and Duy Minh Dang  

E-print Network

1 Quadratic spline collocation for one­dimensional linear parabolic partial differential equations general linear parabolic partial differential equations (PDEs) in one space dimen­ sion are developed. The methods combine quadratic­spline collocation for the space discretization and classical finite differences

Christara, Christina C.

425

Solar Energy.  

ERIC Educational Resources Information Center

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

Eaton, William W.

426

Solar Activity  

NSDL National Science Digital Library

This educational brief provides an overview of solar activity, including a description of Earth's magnetosphere and of various solar phenomena such as the solar wind, Coronal Mass Ejections (CMEs), sunspots, solar flares, and others. A list of links to additional material is also provided.

427

Solar panel  

Microsoft Academic Search

The invention provides a method for heating water by solar radiation using a reflux condenser system in which a heat transfer liquid is boiled by solar radiation and the vapor used to heat the water in a heat exchanger. The solar panel itself is highly efficient in operation and comprises a solar plate which incorporates a number of tubes containing

1978-01-01

428

Solar furnaces  

Microsoft Academic Search

A solar furnace is a device for applying high temperatures to a specimen by concentrating solar radiation on it. A brief historical review concerning the development of solar furnaces is presented and fundamental operational and design principles for solar furnaces are discussed. A paraboloidal mirror is used as a radiation concentrator of the reflection type. According to the procedures used

T. Sakurai

1977-01-01

429

Comparison of photovoltaics with solar thermal trough electric systems as a central station utility resource in the 1990s  

Microsoft Academic Search

The approach and results of work to compare solar thermal parabolic trough systems and photovoltaic systems as utility electric generation resources in the mid-to-late-1990s are discussed. Assumptions, methodology, designs, performance simulation, value analysis, cost estimates, and economic feasibility analysis are presented. Results, based on standard utility financial criteria and avoided costs, show that central station solar power generation is not

Daniel S. Shugar; James M. Eyer; George A. Hay; Jeremy Newberger; David Kearney

1991-01-01

430

Optimization of the mineralization of a mixture of phenolic pollutants under a ferrioxalate-induced solar photo-Fenton process  

Microsoft Academic Search

The mineralization of solutions containing a mixture of three phenolic compounds, gallic, p-coumaric and protocatechuic acids, in a ferrioxalate-induced solar photo-Fenton process was investigated. The reactions were carried out in a pilot plant consisting of a compound parabolic collector (CPC) solar reactor. An optimization study was performed combining a multivariate experimental design and neuronal networks that included the following variables:

J. M. Monteagudo; A. Durn; M. Aguirre; I. San Martn

2011-01-01

431

Solar photoelectro-Fenton degradation of the herbicide 4-chloro-2-methylphenoxyacetic acid optimized by response surface methodology  

Microsoft Academic Search

A central composite rotatable design and response surface methodology (RSM) were used to optimize the experimental variables of the solar photoelectro-Fenton (SPEF) treatment of the herbicide 4-chloro-2-methylphenoxyacetic acid (MCPA). The experiments were made with a flow plant containing a Pt\\/air-diffusion reactor coupled to a solar compound parabolic collector (CPC) under recirculation of 10L of 186mgL?1 MCPA solutions in 0.05M Na2SO4

Sergi Garcia-Segura; Lucio Cesar Almeida; Nerilso Bocchi; Enric Brillas

2011-01-01

432

Solar Systems  

NASA Technical Reports Server (NTRS)

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.

1979-01-01

433

Global Attractor for a Parabolic-Hyperbolic Penrose-Fife Phase Field System  

E-print Network

proposed in [3], indicates that the heat flux is singular in proximity of the absolute zero, whileGlobal Attractor for a Parabolic-Hyperbolic Penrose-Fife Phase Field System Elisabetta Rocca is to analyze the asymptotic behaviour of the associated dynamical system from the point of view of global

Rocca, Elisabetta

434

The Design of a Transmitter with a Parabolic Conical Reflector for a Sonar Ring Lindsay Kleeman  

E-print Network

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

Ohya, Akihisa

435

Dirac mass dynamics in a multidimensional nonlocal parabolic Alexander Lorz # Sepideh Mirrahimi + Benot Perthame +#  

E-print Network

example of Dirac masses approximated by gaussians #(x - ? x) # 1 # 2## e -|x-?x| 2 /2# = e (-|x-?x| 2 -#lnDirac mass dynamics in a multidimensional nonlocal parabolic equation Alexander Lorz # Sepideh)n # (t, x)dx. (1.2) Another and more interesting example is with local interactions # t n # (t, x) = 1

Recanati, Catherine

436

A NOTE ON QUASILINEAR PARABOLIC EQUATIONS ON MANIFOLDS CARLO MANTEGAZZA AND LUCA MARTINAZZI  

E-print Network

in the C ­topology. Our interest in having a handy proof of this result is related to geometric evolution. Introduction 1 2. Proof of the Main Theorem 3 3. Proof of Lemma 2.5 9 4. Parabolic Sobolev Embeddings 11

437

Statistical mechanics for unstable states in Gel'fand triplets and investigations of parabolic potential barriers  

Microsoft Academic Search

Free energies and other thermodynamical quantities are investigated in canonical and grand canonical ensembles of statistical mechanics involving unstable states which are described by the generalized eigenstates with complex energy eigenvalues in the conjugate space of Gel'fand triplet. The theory is applied to the systems containing parabolic potential barriers (PPB's). The entropy and energy productions from PPB systems are studied.

Tsunehiro Kobayashi; Toshiki Shimbori

2001-01-01

438

Complex Eigenvalues of the Parabolic Potential Barrier and Gel'fand Triplet  

Microsoft Academic Search

The paper deals with the one-dimensional parabolic potential barrier\\u000a$V(x)={V_0-m\\\\gamma^2 x^2\\/2}$, as a model of an unstable system in quantum\\u000amechanics. The time-independent Schr\\\\\\

Toshiki Shimbori; Tsunehiro Kobayashi

1999-01-01

439

Non-existence of solutions of semilinear parabolic differential inequalities in cones  

SciTech Connect

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.

Laptev, G G [Tula State University, Tula (Russian Federation)

2001-10-31

440

Solution blow-up for a class of parabolic equations with double nonlinearity  

SciTech Connect

We consider a class of parabolic-type equations with double nonlinearity and derive sufficient conditions for finite time blow-up of its solutions in a bounded domain under the homogeneous Dirichlet condition. To prove the solution blow-up we use a modification of Levine's method. Bibliography: 13 titles.

Korpusov, Maxim O [Lomonosov Moscow State University, Faculty of Physics, Moscow (Russian Federation)] [Lomonosov Moscow State University, Faculty of Physics, Moscow (Russian Federation)

2013-03-31

441

Nuclear spin dynamics in parabolic quantum wells Ionel Tifrea* and Michael E. Flatte  

E-print Network

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

Flatte, Michael E.

442

Equivalence of physical optics and aperture field integration method for parabolic reflectors with offset feeds  

Microsoft Academic Search

This paper discusses the equivalence of physical optics (PO) and the aperture field integration method (AFIM) for the full pattern prediction of parabolic reflectors with offset feeds. In the calculation of the AFIM, there are two important procedures for obtaining the scattered fields. The first one is how to choose the surface of integration. The second one is how to

M. Oodo; K. Hara; M. Ando

1997-01-01

443

Numerical code for the three-dimensional parabolic wave equation. [TAP 1 and TAP 2  

Microsoft Academic Search

Various features of a code designed to solve the three-dimensional parabolic wave equation with an added nonlinear (self-focusing) term are summarized. Some exact conservation laws of the full nonlinear equation are considered. The precise numerical method used to solve the equation is explicitly displayed. Comparisons of numerically computed results with exact results for a sample pure diffraction problem are made.

Goldstein

1977-01-01

444

Implicit-explicit multistep finite element methods for nonlinear parabolic problems  

Microsoft Academic Search

We approximate the solution of initial boundary value problems for nonlinear parabolic equations. In space we discretize by nite element methods. The discretization in time is based on linear multistep schemes. One part of the equation is discretized implicitly and the other explicitly. The resulting schemes are stable, consistent and very ecient, since their im- plementation requires at each time

Georgios Akrivis; Michel Crouzeix; Charalambos Makridakis

1998-01-01

445

A second-order accurate parabolized Navier-Stokes algorithm for internal flows  

NASA Technical Reports Server (NTRS)

A parabolized implicit Navier-Stokes algorithm which is of second-order accuracy in both the cross flow and marching directions is presented. The algorithm is used to analyze three model supersonic flow problems (the flow over a 10-degree edge). The results are found to be in good agreement with the results of other techniques available in the literature.

Chitsomboon, T.; Tiwari, S. N.

1984-01-01

446

Estimates for the quenching time of a parabolic equation modeling electrostatic MEMS  

E-print Network

Estimates for the quenching time of a parabolic equation modeling electrostatic MEMS Nassif the dynamic deflection of an elastic membrane in a simple electrostatic Micro-Electromechanical System (MEMS(x). Key words: electrostatic MEMS; quenching time; quenching set. 1 Introduction Micro

Ghoussoub, Nassif

447

Roto-vibrational spectrum and Wigner crystallization in two-electron parabolic quantum dots  

Microsoft Academic Search

We provide a quantitative determination of the crystallization onset for two electrons in a parabolic two-dimensional confinement. This system is shown to be well described by a rotovibrational model, Wigner crystallization occurring when the rotational motion gets decoupled from the vibrational one. The Wigner molecule thus formed is characterized by its moment of inertia and by the corresponding sequence of

Antonio Puente; Lloren Serra; Rashid G. Nazmitdinov

2004-01-01

448

Application of the Parabolic Approximation to Predict Acoustical Propagation in the Ocean.  

ERIC Educational Resources Information Center

A simplified derivation of the parabolic approximation to the acoustical wave equation is presented. Exact solutions to this approximate equation are compared with solutions to the wave equation to demonstrate the applicability of this method to the study of underwater sound propagation. (Author/BB)

McDaniel, Suzanne T.

1979-01-01

449

An Investigation of the Relation Between the Developmental Parabolic Curve and Selected Personality Variables.  

ERIC Educational Resources Information Center

This study is designed to determine whether data obtained cross-sectionally from a sample of subjects in the middle childhood range on selected personality characteristics could be well described by a concave parabolic curve and thus linked to the closure behaviour elicited from the subjects. Specifically, the investigation seeks to determine if

Flugsrud, Marcia R.

450

Acoustic field associated with parabolized stability equation models in turbulent jets  

E-print Network

Acoustic field associated with parabolized stability equation models in turbulent jets Daniel Rodr, the acoustic far-field associated with the PSE wavepackets is computed using a Kirchhoff surface method that the noise radiated to the acoustic far-field is mostly contained in the first few azimuthal wavenumbers

Dabiri, John O.

451

Extension of the Piecewise Parabolic Method to One-Dimensional Relativistic Hydrodynamics  

NASA Astrophysics Data System (ADS)

An extension to 1D relativistic hydrodynamics of the piecewise parabolic method (PPM) of Colella and Woodward using an exact relativistic Riemann solver is presented. Results of several tests involving ultrarelativistic flows, strong shocks and interacting discontinuities are shown. A comparison with Godunov's method demonstrates that the main features of PPM are retained in our relativistic version.

Mart, Jos M. a.; Mller, Ewald

1996-01-01

452

Detection, Isolation and Management of Actuator Faults in Parabolic PDEs under Uncertainty and Constraints  

E-print Network

Detection, Isolation and Management of Actuator Faults in Parabolic PDEs under Uncertainty-varying uncertain variables, actuator constraints and faults. The design is based on an approximate, finite transformation, obtained with judicious actuator placement, is used to transform the approximate system

Sontag, Eduardo

453

FINITE DIFFERENCE SCHEMES FOR THE `PARABOLIC' EQUATION IN A VARIABLE DEPTH ENVIRONMENT  

E-print Network

. We consider a linear, Schr¨odinger type p.d.e., the `Parabolic' Equation of underwater acoustics Equation (PE), [T], [LMc2], is widely used in underwater acoustics as a model for the simulation of one-way, long-range sound propagation near a horizontal plane, in inhomogeneous, weakly range-dependent marine

Akrivis, Georgios

454

Parabolic flight experience is related to increased release of stress hormones.  

PubMed

Numerous studies have shown significant effects of weightlessness on adaptational processes of the CNS, cardiovascular and/or muscular system. Most of these studies have been carried out during parabolic flights, using the recurring 20 s of weightlessness at each parabola. Although some of these studies reported on potential influences not only of weightlessness but also of the stressful situation within a parabolic flight, especially provoked by the ongoing changes between 1.8, 1 and 0 G, so far there seems to be only marginal information about objective parameters of stress evoked by parabolic flights. By collecting blood samples from a permanent venous catheter several times during parabolic flights, we were able to show an increase of prolactin, cortisol and ACTH in the course of a 120 min flight. We conclude, therefore, that previous reported effects of weightlessness on adaptational processes may be affected not only by weightlessness but also by the exposure to other stressors experienced within the environment of a Zero-G airbus. PMID:17351784

Schneider, Stefan; Brmmer, Vera; Gbel, Simon; Carnahan, Heather; Dubrowski, Adam; Strder, Heiko K

2007-06-01

455

Efficiency of the Regulation of Otolith Mineralisation and Susceptibility to kinetotic Behaviour in Parabolic Aircraft Flights  

Microsoft Academic Search

Under diminished gravity e g during the respective phase in the course of parabolic aircraft flight PF humans often suffer from motion sickness a kinetsosis due to sensorimotor disorders Using fish as a model system we previously provided ample evidence that an individually differently pronounced asymmetric mineralisation calcification of inner ear stones otoliths leads to the individually different susceptibility to

M. Knie; J. Weigele; R. Hilbig; R. Anken

2006-01-01

456

A new ESA educational initiative: Euro Space Center class teachers in microgravity during parabolic flights  

Microsoft Academic Search

Since 1984, the European Space Agency (ESA) has organized 30 aircraft parabolic flight campaigns in the frame of its Microgravity Programme to perform short duration scientific and technological experiments. On each campaign, ESA invites journalists to report to the general public on the research work conducted in weightlessness. A new initiative was launched in 2000 with the introduction of pedagogical

Vladimir Pletser; Pierre Emmanuel Paulis; Edwin Loosveldt; Dominique Gering; Mireille Body; Robert Schewijck

2005-01-01

457

Shift in arm-pointing movements during gravity changes produced by aircraft parabolic flight.  

PubMed

It has been shown that target-pointing arm movements without visual feedback shift downward in space microgravity and upward in centrifuge hypergravity. Under gravity changes in aircraft parabolic flight, however, arm movements have been reported shifting upward in hypergravity as well, but a downward shift under microgravity is contradicted. In order to explain this discrepancy, we reexamined the pointing movements using an experimental design which was different from prior ones. Arm-pointing movements were measured by goniometry around the shoulder joint of subjects with and without eyes closed or with a weight in the hand, during hyper- and microgravity in parabolic flight. Subjects were fastened securely to the seat with the neck fixed and the elbow maintained in an extended position, and the eyes were kept closed for a period of time before each episode of parabolic flight. Under these new conditions, the arm consistently shifted downward during microgravity and mostly upward during hypergravity, as expected. We concluded that arm-pointing deviation induced by parabolic flight could be also be valid for studying the mechanism underlying disorientation under varying gravity conditions. PMID:11542494

Chen, Y; Mori, S; Koga, K; Ohta, Y; Wada, Y; Tanaka, M

1999-06-01

458

FINITE DIFFERENCE METHODS AND SPATIAL A POSTERIORI ERROR ESTIMATES FOR SOLVING PARABOLIC EQUATIONS IN THREE SPACE  

E-print Network

FINITE DIFFERENCE METHODS AND SPATIAL A POSTERIORI ERROR ESTIMATES FOR SOLVING PARABOLIC EQUATIONS on finite element methods. In this paper modified finite difference approximations are obtained for grids a posteriori error estimates of the spatial error are presented for the finite difference method

Moore, Peter K.

459

Solving parabolic and hyperbolic equations by the generalized finite difference method  

Microsoft Academic Search

Classical finite difference schemes are in wide use today for approximately solving partial differential equations of mathematical physics. An evolution of the method of finite differences has been the development of generalized finite difference (GFD) method, that can be applied to irregular grids of points.In this paper the extension of the GFD to the explicit solution of parabolic and hyperbolic

J. J. Benito; F. Urena; L. Gavete

2007-01-01

460

Solar installation for process steam generation for a refinery  

NASA Astrophysics Data System (ADS)

A solar thermal system for steam generation in a refinery is presented. The system is installed in the Southern Union Refinery in Hobbs, New Mexico, U.S.A. The refinery processes 36,000 BPSD of crude oil (42 U.S. gallon barrels of product fuels per steam day). The solar system is a two loop system. A heat transfer oil (Therminol T-55) circulates through an array of parabolic collectors of 936 sq m area while saturated steam at 190 C/12 kg/sq m is generated in the steam generator loop. The steam flow is 658 kg/hr. A data acquisition system (ODAS) was designed and assembled to evaluate the solar system's thermal performance. It is expected that on an annual basis the solar system will provide a thermal process heat equivalent to 93,400 cu m of natural gas.

Clark, L. D.; Hudson, S.; Pytlinski, J. T.; Lumsdaine, E.; Bridgers, F.

461

Design of a Thermal Imaging Diagnostic Using 90-Degree, Off-Axis, Parabolic Mirrors  

SciTech Connect

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 30005000-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 9001700 nm, and at 17003000 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.

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

462

Design of a thermal imaging diagnostic using 90-degree off-axis parabolic mirrors  

NASA Astrophysics Data System (ADS)

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 time-resolved 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.

Malone, Robert M.; Becker, Steven A.; Dolan, Daniel H.; Hacking, Richard G.; Hickman, Randy J.; Kaufman, Morris I.; Stevens, Gerald D.; Turley, William D.

2006-08-01

463

The sun-tracking control of solar collectors using high-performance step motors  

NASA Technical Reports Server (NTRS)

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.

Hughes, R. O.

1977-01-01

464

Development of mass-producible line-focus tracking concentrating solar collectors. Category 2: Control systems  

NASA Astrophysics Data System (ADS)

The system design criteria and concept of a mass producible modular electronic control system for solar industrial process heating installations are discussed. The control system consists of: the master controller; the weather tower, including a solar tracking angle reference; and overtemperature switch, group control box, tracker/controller, and drive motor for each group of single axis tracking parabolic trough solar collectors. System automatic operation is outlined for unattended installations. The production approach and cost estimates, both based on a production rate of 5 million ft(2) of collector aperature per year, are discussed here. The potential for further development of the system is also presented.

Hickman, T. E.

1984-08-01

465

Solar System  

NSDL National Science Digital Library

At the end of this project, you will be able to explain the components of the Solar System and know the order of the planets starting from the Sun. Objective Question: What is the Solar System? First, listen and read about the Solar System 1. How many planets make up our Solar System? 2. What is at the center of the Solar System? Next,listen and read about the Planets. 1. Can you name all of the planets? Finally, listen and watch The Solar System Movie. 1. Can you list the ...

Ms.west

2009-07-07

466

Solar Collectors  

NASA Technical Reports Server (NTRS)

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.

1980-01-01

467

Absence of E. coli regrowth after Fe 3+ and TiO 2 solar photoassisted disinfection of water in CPC solar photoreactor  

Microsoft Academic Search

Field disinfection of water in a large solar compound parabolic collector (CPC) photoreactor (3570l) was conducted at 35C by different photocatalytic processes: sunlight\\/TiO2, sunlight\\/TiO2\\/Fe3+, sunlight\\/Fe3+\\/H2O2 and compared to the control experiment of direct sunlight alone. Experiments were carried out using a CPC and natural water spiked with E. coli K 12. Under these conditions, total disinfection by bare sunlight irradiation

Angela-Guiovana Rincn; Cesar Pulgarin

2007-01-01

468

Detailed Physical Trough Model for NREL's Solar Advisor Model: Preprint  

SciTech Connect

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.

Wagner, M. J.; Blair, N.; Dobos, A.

2010-10-01

469

Solar Geometry  

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 ...

2014-09-25

470

Solar Cooking  

... (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 ...

2014-09-25

471

Solar System  

Microsoft Academic Search

The region of the universe in which we live, the Solar System, is but one of many clusters of stars and planets in space. Our Solar System lies in a particular region of the universe called the `Milky Way Galaxy'....

P. Masson

2000-01-01

472

Solar disinfection of wild Salmonella sp. in natural water with a 18 L CPC photoreactor: Detrimental effect of non-sterile storage of treated water  

Microsoft Academic Search

For the first time solar disinfection of liters of water containing wild Salmonella sp. and total coliforms was carried out in a compound parabolic collector (CPC) photoreactor at temperatures of almost 50C. Using surface water with high turbidity, this treatment was efficient in completely inactivating Salmonella sp. without regrowth during the subsequent 72h of dark sterile storage. However if the

Frdric Sciacca; Julin A. Rengifo-Herrera; Joseph Wth; Csar Pulgarin

2011-01-01

473

Solar Flares  

NSDL National Science Digital Library

This page details and resources that help support an understanding of solar flares on our sun. When we are drawing a sun on a piece of paper, they usually look like this: Cartoon Picture of a Sun The spiky lines have a name - Solar Flares. This is when the sun releases gas and heat into the atmosphere. Click on this picture to see what a solar flare looks like. Picture of a Solar Flare 2 In this video, you ...

Mrs. Verlengia

2011-12-10

474

Solar Distillation  

Microsoft Academic Search

\\u000a Solar distillation is a technology for producing potable water from brackish and underground water of low-quality at low\\u000a cost. It can reduce water-scarcity problems together with other water purification technologies. Solar distillation is analogous\\u000a to natural hydrological cycle. It uses an apparatus called a solar still in which water is evaporated using solar energy,\\u000a a form of renewable energy, and

Rahul Dev; Gopal Nath Tiwari

475

Solar panel  

Microsoft Academic Search

A solar collector for use in receiving solar radiation and converting the same to heat. A matrix of plural layers of slit-and-expanded sheets are contained within the solar collector and the heat produced by the matrix absorbing solar radiation is transferred by convection into a forced fluid path. The surfaces of the slit-and-expanded sheets are coated to absorb and convert

Schriefer; A. H. Jr

1978-01-01

476

Solar panel  

Microsoft Academic Search

A solar collector for use in receiving solar radiation and converting the same to heat is described. A matrix of plural layers of slit-and-expanded sheets are contained within the solar collector and the heat produced by the matrix absorbing solar radiation is transferred by convection into a forced fluid path. The surfaces of the slit-and-expanded sheets are coated to absorb

Schriefer; A. H. Jr

1979-01-01

477

Solar Equipment  

NASA Technical Reports Server (NTRS)

A medical refrigeration and a water pump both powered by solar cells that convert sunlight directly into electricity are among the line of solar powered equipment manufactured by IUS (Independent Utility Systems) for use in areas where conventional power is not available. IUS benefited from NASA technology incorporated in the solar panel design and from assistance provided by Kerr Industrial Applications Center.

1983-01-01

478

Solar panel  

Microsoft Academic Search

A solar panel has an interior insulated heat storage means, a solar radiation collector wall mounted on a first side of the storage means having a collector surface for exposure to solar radiation, and a heat emitter wall mounted on a second side of the heat storage means opposite the first side having an emitter surface for exposure to a

K. Schmid; G. Wagner

1982-01-01

479

Solar furnace  

Microsoft Academic Search

The solar furnace is constructed of evacuated glass block solar elements that include an interior face, or surface, of zinc. Because of this material, substantial solar radiant energy is retained and radiated to the interior of the furnace, permitting the furnace to reach temperatures of 300° C. and more when located at latitudes between the 35th parallels. Evacuated insulating elements

Clavier

1985-01-01

480

Theoretical analysis of error transfer from surface slope to refractive ray and their application to the solar concentrated collector  

E-print Network

This paper presents the general equation to calculate the standard deviation of reflected ray error from optical error through geometry optics, applying the equation to calculate the standard deviation of reflected ray error for 8 kinds of solar concentrated reflector, provide typical results. The results indicate that the slope errors in two direction is transferred to any one direction of the focus ray when the incidence angle is more than 0 for solar trough and heliostats reflector; for point focus Fresnel lens, point focus parabolic glass mirror, line focus parabolic galss mirror, the error transferring coefficient from optical to focus ray will increase when the rim angle increase; for TIR-R concentrator, it will decrease; for glass heliostat, it relates to the incidence angle and azimuth of the reflecting point. Keywords: optic error, standard deviation, refractive ray error, concentrated solar collector

Huang, Weidong

2011-01-01

481

On the stochastic homogenization of fully nonlinear uniformly parabolic equations in stationary ergodic spatio-temporal media  

NASA Astrophysics Data System (ADS)

We study homogenization for fully nonlinear uniformly parabolic equations in stationary ergodic spatio-temporal media from the qualitative and quantitative perspectives. Under suitable hypotheses, solutions to fully nonlinear uniformly parabolic equations in spatio-temporal media homogenize almost surely. In addition, we obtain a logarithmic rate of convergence for this homogenization in measure, assuming that the environment is strongly mixing with a prescribed logarithmic rate. A general methodology to study the stochastic homogenization and rates of convergence for stochastic homogenization of uniformly elliptic equations was introduced by Caffarelli, Souganidis, and Wang [1], and Caffarelli and Souganidis [2]. We extend their approach to fully nonlinear uniformly parabolic equations, developing a number of new arguments to handle the parabolic structure of the problem.

Lin, Jessica

2015-02-01

482

Role of the vestibular system in the arterial pressure response to parabolic-flight-induced gravitational changes in human subjects.  

PubMed

Arterial pressure (AP) is known to fluctuate during parabolic-flight-induced gravitational changes in human subjects, increasing during hypergravity and decreasing during microgravity. In this study, we examined whether the vestibular system participates in the AP response to the gravitational changes induced by parabolic flight in human subjects. Eight subjects performed parabolic flights in a supine position as their AP was measured. Their vestibular inputs during the gravitational changes were reversibly masked by artificial electrical stimulation (galvanic vestibular stimulation, GVS). The AP responses during the parabolas were then compared between the GVS-off and GVS-on conditions. AP increased during hypergravity and decreased during microgravity. The AP responses at the onset of hypergravity and microgravity were abolished by GVS. These results indicate that the vestibular system elicits pressor and depressor responses during parabolic-flight-induced hypergravity and microgravity, respectively. PMID:21440600

Iwata, Chihiro; Abe, Chikara; Tanaka, Kunihiko; Morita, Hironobu

2011-05-16

483

LCA (Life Cycle Assessment) of Parabolic Trough CSP: Materials Inventory and Embodied GHG Emissions from Two-Tank Indirect and Thermocline Thermal Storage (Presentation)  

SciTech Connect

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.

Heath, G.; Burkhardt, J.; Turchi, C.; Decker, T.; Kutscher, C.

2009-07-20

484

Solar Neutrinos  

E-print Network

Present results and future measurements of solar neutrinos are discussed. The results to date indicate that solar electron neutrinos are changing to other active types and that transitions solely to sterile neutrinos are disfavored. The flux of $^{8}B$ solar neutrinos produced in the Sun, inferred assuming only active neutrino types, is found to be in very good agreement with solar model calculations. Future measurements will focus on greater accuracy for charged current and neutral current sensitive reactions to provide more accurate measurements of neutrino flavour change and further studies of day-night flux differences and spectral shape. Other experiments sensitive to lower energy solar neutrinos will be in operation soon.

A. B. McDonald

2002-09-21

485

Solar Meter  

NASA Technical Reports Server (NTRS)

The instrument pictured is an inexpensive solar meter which is finding wide acceptance among architects, engineers and others engaged in construction of solar energy facilities. It detects the amount of solar energy available at a building site, information necessary to design the most efficient type of solar system for a particular location. Incorporating technology developed by NASA's Lewis Research Center, the device is based upon the solar cell, which provides power for spacecraft by converting the sun's energy to electricity. The meter is produced by Dodge Products, Inc., Houston, Texas, a company formed to bring the technology to the commercial marketplace.

1978-01-01

486

Oscillation of electron mobility in parabolic double quantum well structure due to applied electric field  

NASA Astrophysics Data System (ADS)

We show that oscillation of low temperature electron mobility ? can be obtained by applying an electric field F along the growth direction of the asymmetrically barrier delta doped AlxGa1-xAs parabolic double quantum well structure. The drastic changes in the subband Fermi energies and distributions of subband wave functions as a function of F yield nonmonotonic intra- and intersubband scattering rate matrix elements mediated by intersubband effects. The oscillatory enhancement of ?, which is attributed to the subband mobilities governed by the ionized impurity scattering, magnifies with increase in well width and decrease in height of the parabolic structure potential. The results can be utilized for nanoscale low temperature device applications.

Sahoo, Narayan; Sahu, Trinath

2014-12-01

487

Role of secondary instability theory and parabolized stability equations in transition modeling  

NASA Technical Reports Server (NTRS)

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.

El-Hady, Nabil M.; Dinavahi, Surya P.; Chang, Chau-Lyan; Zang, Thomas A.

1993-01-01

488

Linear and nonlinear optical absorption coefficients of two-electron spherical quantum dot with parabolic potential  

NASA Astrophysics Data System (ADS)

Linear and nonlinear absorption coefficients of two-electron spherical quantum dot (QD) with parabolic potential are investigated in this paper. Wave functions and energy eigenvalues of the 1s2, 1s1p, 1s1d and 1s1f electronic states have been computed by using an optimization approach, which is a combination of Quantum Genetic Algorithm (QGA) and Hartree-Fock Roothaan (HFR) method. It is found that the strength of S?P transition is stronger than P?D and D?F transitions. Also the peak positions and amplitudes of the absorption coefficients are sensitive to the electron spin. It should be noted that the peak positions and amplitudes of absorption coefficients are strongly dependent on the parabolic potential. Additionally, dot radius, impurity charge, incident optical intensity and relaxation time have a great influence on the linear and nonlinear absorption coefficients.

ak?r, Bekir; Yakar, Yusuf; zmen, Ayhan

2015-02-01

489

Low-frequency sound propagation modeling over a locally-reacting boundary using the parabolic approximation  

NASA Technical Reports Server (NTRS)

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.

Robertson, J. S.; Siegman, W. L.; Jacobson, M. J.

1989-01-01

490

On the parabolic Stefan problem for Ostwald ripening with kinetic undercooling and inhomogeneous driving force  

NASA Astrophysics Data System (ADS)

Ostwald ripening is the coarsening phenomenon caused by the diffusion and solidification process which occurs in the last stage of a first-order phase transformation. The force that drives the system towards equilibrium is the gradient of the chemical potential that, according to the Gibbs-Thomson condition, on the interface, is proportional to its mean curvature. A quantitative description of Ostwald ripening has been developed by the Lifschitz-Slyozov-Wagner (LSW) theory. We extend the work of Niethammer (2000) [15] which deals with kinetic undercooling in the quasi-static case to the parabolic setting with temporally inhomogeneous driving forces on the solid-liquid interfaces. By means of a priori estimates, local and global existence results for the parabolic Stefan problem, we derive a first order approximation for the dynamical equations for the heat distribution and particle radii and then prove the convergence to a limiting description using a mean-field equation.

Antonopoulou, D. C.; Karali, G. D.; Yip, N. K.

491

Generation of parabolic bound pulses from a Yb-fiber laser  

NASA Astrophysics Data System (ADS)

We report the observation of self-similar propagation of bound-state pulses in an ytterbium-doped double-clad fiber laser. A bound state of two positively chirped parabolic pulses with 5.4 ps duration separated by 14.9 ps is obtained, with 1.7 nJ of energy per pulse. These pulses are extra-cavity compressed to 100 fs. For higher pumping power and a different setting of the intra-cavity polarization controllers, the laser generates a bound state of three chirped parabolic pulses with different time separations and more than 1.5 nJ energy per pulse. Perturbation of this bound state by decreasing pump power results in the generation of a single pulse and a two-pulse bound state both structures traveling at the same velocity along the cavity. A possible explanation of the zero relative speed by a particular phase relation of the bound states is discussed.

Orta, B.; Hideur, A.; Brunel, M.; Chdot, C.; Limpert, J.; Tnnermann, A.; Ilday, F. .

2006-06-01

492

Blow-up rates for higher-order semilinear parabolic equations and systems and some Fujita-type theorems  

NASA Astrophysics Data System (ADS)

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.

Pan, Hongjing; Xing, Ruixiang

2008-03-01

493

Homogenization of a singularly perturbed degenerated parabolic equation and application to seabed dune and megaripple morphodynamics in tided environment  

E-print Network

In this paper we build models for short-term, mean-term and long-term dynamics of dune and megariple morphodynamics. They are models that are degenerated parabolic equations which are, moreover, singularly perturbed. We, then give an existence and uniqueness result for the short-term and mean-term models. This result is based on a time-space periodic solution existence result for degenerated parabolic equation that we set out. Finally the short-term model is homogenized.

Faye, Ibrahima; Seck, Diaraf

2009-01-01

494

A solution-adaptive grid procedure for the three-dimensional parabolized Navier-Stokes equations  

NASA Technical Reports Server (NTRS)

A solution-adaptive grid procedure for the three-dimensional parabolized Navier-Stokes equations is developed on the basis of the two-dimensional line-by-line solution-adaptive technique of Harvey et al. (1990). It is shown that the new adaptive grid algorithm provides improved shock resolving characteristics over the conventional flow algorithm. The adaptation process has the ability of aligning grid lines with the existing flow-field structure, yielding increasing resolution of high gradient regions.

Harvey, Albert D., III; Acharya, Sumanta; Lawrence, Scott L.

1991-01-01

495

Arrays of Microplasma Jets Generated by Double Parabolic Microcavities in an Hourglass Configuration  

Microsoft Academic Search

Microplasma jets have been generated in double par- abolic microcavities arranged in an hourglass structure with a 300-m-diameter throat. Fabricated by micropowder blasting of nanoporous alumina grown on Al foil, the parabolic cavities are situated back-to-back and operated with a feedstock gas having a flow rate of?1.5-6 standard L\\/min. Arrays as large as 6 6j ets have been demonstrated

J. H. Cho; M. H. Kim; S.-J. Park; J. G. Eden

2011-01-01

496

Multigrid second-order accurate solution of parabolic control-constrained problems  

Microsoft Academic Search

A mesh-independent and second-order accurate multigrid strategy to solve control-constrained parabolic optimal control problems\\u000a is presented. The resulting algorithms appear to be robust with respect to change of values of the control parameters and\\u000a have the ability to accommodate constraints on the control also in the limit case of bang-bang control. Central to the development\\u000a of these multigrid schemes is

A. Borz

2012-01-01

497

Statistical mechanics for unstable states in Gel'fand triplets and investigations of parabolic potential barriers.  

PubMed

Free energies and other thermodynamical quantities are investigated in canonical and grand canonical ensembles of statistical mechanics involving unstable states which are described by the generalized eigenstates with complex energy eigenvalues in the conjugate space of Gel'fand triplet. The theory is applied to the systems containing parabolic potential barriers (PPB's). The entropy and energy productions from PPB systems are studied. An equilibrium for a chemical process described by reactions A+CB <==>AC+B is also discussed. PMID:11414955

Kobayashi, T; Shimbori, T

2001-05-01

498

Computation of Parabolic Cylinder Functions by Means of a Tricomi Expansion  

NASA Astrophysics Data System (ADS)

Fast convergence expansion of the parabolic cylinder functions U( a, x), V( a, x), W( a, x) is obtained in terms of the Tricomi functions Ev( z). The numerical results are quite accurate for a large interval of values of " a" and for | x| ? 7. Tables are given for U and V in order to compare our results with other recent works on the same functions.

Maino, G.; Menapace, E.; Ventura, A.

1981-04-01

499

Quantum damped oscillator II: Bateman's Hamiltonian vs. 2D parabolic potential barrier  

SciTech Connect

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.

Chruscinski, Dariusz [Institute of Physics, Nicolaus Copernicus University, ul. Grudziadzka 5/7, 87-100 Torun (Poland)]. E-mail: darch@phys.uni.torun.pl

2006-04-15

500

Transition between free-space Helmholtz equation solutions with plane sources and parabolic wave equation solutions.  

PubMed

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

Mahillo-Isla, R; Gon?alez-Morales, M J; Dehesa-Martnez, C

2011-06-01