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1

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.

2

Reflective Solar Cooker  

NSDL National Science Digital Library

In this activity, learners use the Sun's energy to cook marshmallows. Learners construct the solar oven out of simple everyday materials. They experiment to see how the color of the marshmallow (vanilla or chocolate) and height of the straws affect cooking time. Use this activity to introduce learners to solar energy and reflection. Note: this activity requires adult supervision.

Observatory, Mcdonald

2011-01-01

3

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

4

Solar Week Thursday: Solar Pizza Box Cooker  

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 cooker by lining a box with reflective material and adding a translucent cover. 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.

5

Nature's Kitchen: Solar Box Cooker Experiment  

NSDL National Science Digital Library

The Materials Science and Technology Teacher's Workshop (MAST) provides this activity to support solar energy curriculum. The goal of the experiment is to allow students to create a device to cook food with energy from the sun. The experiment teaches the procedures to build a solar cooker to use if trapped without a cooking stove while camping. The introduction is very basic and the instructor can opt to build the solar cooker beforehand to save class time. In the end, several cookers will be built, and their degree of cooking effectiveness is monitored through several small pieces of potatoes cooked over several hours.The lesson includes step by step directions for the experiment. Discussion questions and teacher notes are also included.

2012-03-15

6

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

7

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

8

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

9

Thermal performance study of box type solar cooker from heating characteristic curves  

Microsoft Academic Search

The top heat losses that constitute the major losses from the box type solar cooker have a strong influence on the thermal performance. To predict or evaluate the thermal performance of a cooker, the top heat loss coefficient Utw for a water loaded cooker must be known. In the present study, several indoor and outdoor experiments were performed on a

Subodh Kumar

2004-01-01

10

The ``Sol Kitchen'' solar coffee can cooker kit and curriculum package  

SciTech Connect

The Sol Kitchen Solar Coffee Can Cooker Kit is being developed, by Solar utilities, as a product, with several contexts in mind, including (1) the need to sustain the long term market development of solar energy through education, (2) the need for an improved set of performance criteria for the technology, as it is presented in the classroom and (3) an awareness of newly evolving bench marks in environmental education ({hor_ellipsis}which is about learning how to save the earth.). The category of technology discussed in this paper is the solar cooker, also known as, the solar oven, furnace, or box cooker, with or without reflective panels. The use of full scale solar cookers, modified to act as curriculum aids, can augment educational programs; but only if they work well, are appropriate to the educational objectives, and engage the attention and active involvement of the learners.

Donald, R.M.

1999-07-01

11

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

12

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.

Sales, J H O

2009-01-01

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

Solar parabolic dish technology evaluation report  

NASA Technical Reports Server (NTRS)

The activities of the JPL Solar Thermal Power Systems Parabolic Dish Project for FY 1983 are summarized. Included are discussions on designs of module development including concentrator, receiver, and power conversion subsystems together with a separate discussion of field tests, Small Community Experiment system development, and tests at the Parabolic Dish Test Site.

Lucas, J. W.

1984-01-01

15

Solar parabolic dish technology evaluation report  

NASA Astrophysics Data System (ADS)

The activities of the JPL Solar Thermal Power Systems Parabolic Dish Project for FY 1983 are summarized. Included are discussions on designs of module development including concentrator, receiver, and power conversion subsystems together with a separate discussion of field tests, Small Community Experiment system development, and tests at the Parabolic Dish Test Site.

Lucas, J. W.

1984-04-01

16

Parabolic dish collectors - A solar option  

Microsoft Academic Search

A description is given of several parabolic-dish high temperature solar thermal systems currently undergoing performance trials. A single parabolic dish has the potential for generating 20 to 30 kW of electricity with fluid temperatures from 300 to 1650 C. Each dish is a complete power-producing unit, and may function either independently or as part of a group of linked modules.

V. C. Truscello

1981-01-01

17

Building a parabolic solar concentrator prototype  

Microsoft Academic Search

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

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

2011-01-01

18

Parabolic dish collectors - A solar option  

NASA Technical Reports Server (NTRS)

A description is given of several parabolic-dish high temperature solar thermal systems currently undergoing performance trials. A single parabolic dish has the potential for generating 20 to 30 kW of electricity with fluid temperatures from 300 to 1650 C. Each dish is a complete power-producing unit, and may function either independently or as part of a group of linked modules. The two dish designs under consideration are of 11 and 12 meter diameters, yielding receiver operating temperatures of 925 and 815 C, respectively. The receiver designs described include (1) an organic working fluid (toluene) Rankine cycle engine; (2) a Brayton open cycle unit incorporating a hybrid combustion chamber and nozzle and a shaft-coupled permanent magnet alternator; and (3) a modified Stirling cycle device originally designed for automotive use. Also considered are thermal buffer energy storage and thermochemical transport and storage.

Truscello, V. C.

1981-01-01

19

Parabolic dish collectors - A solar option  

NASA Astrophysics Data System (ADS)

A description is given of several parabolic-dish high temperature solar thermal systems currently undergoing performance trials. A single parabolic dish has the potential for generating 20 to 30 kW of electricity with fluid temperatures from 300 to 1650 C. Each dish is a complete power-producing unit, and may function either independently or as part of a group of linked modules. The two dish designs under consideration are of 11 and 12 meter diameters, yielding receiver operating temperatures of 925 and 815 C, respectively. The receiver designs described include (1) an organic working fluid (toluene) Rankine cycle engine; (2) a Brayton open cycle unit incorporating a hybrid combustion chamber and nozzle and a shaft-coupled permanent magnet alternator; and (3) a modified Stirling cycle device originally designed for automotive use. Also considered are thermal buffer energy storage and thermochemical transport and storage.

Truscello, V. C.

1981-05-01

20

Solar cookers with and without thermal storageA review  

Microsoft Academic Search

The continuous increase in the level of green house gas emissions and the increase in fuel prices are the main driving forces behind efforts to more effectively utilize various sources of renewable energy. In many parts of the world, direct solar radiation is considered to be one of the most prospective sources of energy. Among the different energy end uses,

R. M. Muthusivagami; R. Velraj; R. Sethumadhavan

2010-01-01

21

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

22

Proceedings of the Fifth Parabolic Dish Solar Thermal Power Program  

NASA Technical Reports Server (NTRS)

The proceedings of the Fifth Parabolic Dish Solar Thermal Power Program Annual Review are presented. The results of activities within the Parabolic Dish Technology and Module/Systems Development element of the Department of Energy's Solar Thermal Energy Systems Program were emphasized. Among the topics discussed were: overall Project and Program aspects, Stirling and Brayton module development, concentrator and engine/receiver development along with associated hardware and test results; distributed systems operating experience; international parabolic dish development activities; and non-DOE-sponsored domestic dish activities. Solar electric generation was also addressed.

Lucas, J. W. (editor)

1984-01-01

23

Solar parabolic dish annual technology evaluation report. Fiscal year 1982  

SciTech Connect

This report summarizes the activities of the JPL Solar Thermal Power Systems Parabolic Dish Project for FY 1982. 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.

Not Available

1983-09-15

24

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

25

Solar Thermal Power Plants with Parabolic-Trough Collectors  

NASA Astrophysics Data System (ADS)

Parabolic-trough collectors (PTC) are solar concentrating devices suitable to work in the 150C- 400C temperature range. Power plants based on this type of solar collectors are a very efficient way to produce electricity with solar energy. At present, there are eight commercial solar plants (called SEGS-II, III,.. IX) producing electricity with parabolic-trough collectors and their total output power is 340 MW. Though all SEGS plants currently in operation use thermal oil as a heat transfer fluid between the solar field and the power block, direct steam generation (DSG) in the receiver tubes is a promising option to reduce the cost of electricity produced with parabolic- trough power plants. Most of technical uncertainties associated to the DSG technology were studied and solved in the DISS project and it is expected that this new technology will be commercially available in a short term. In Spain, the Royal Decree No. 436/204 (March 12th , 2004) has defined a premium of 0,18/kWh for the electricity produced by solar thermal power plants, thus promoting the installation of solar thermal power plants up to a limit of 200 MW. Due to the current legal and financial framework defined in Spain, several projects to install commercial solar power plants with parabolic-trough collectors are currently underway.

Zarza, E.; Valenzuela, L.; Len, J.

2004-12-01

26

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

27

Parabolic Trough Solar Power for Competitive U.S. Markets  

SciTech Connect

Nine parabolic trough power plants located in the California Mojave Desert represent the only commercial development of large-scale solar power plants to date. Although all nine plants continue to operate today, no new solar power plants have been completed since 1990. Over the last several years, the parabolic trough industry has focused much of its efforts on international market opportunities. Although the power market in developing countries appears to offer a number of opportunities for parabolic trough technologies due to high growth and the availability of special financial incentives for renewables, these markets are also plagued with many difficulties for developers. In recent years, there has been some renewed interest in the U.S. domestic power market as a result of an emerging green market and green pricing incentives. Unfortunately, many of these market opportunities and incentives focus on smaller, more modular technologies (such as photovoltaics or wind power), and as a result they tend to exclude or are of minimum long-term benefit to large-scale concentrating solar power technologies. This paper looks at what is necessary for large-scale parabolic trough solar power plants to compete with state-of-the-art fossil power technology in a competitive U.S. power market.

Henry W. Price

1998-11-01

28

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

29

Proceedings: Fourth Parabolic Dish Solar Thermal Power Program Review  

NASA Astrophysics Data System (ADS)

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.

1983-02-01

30

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

31

Irrigation market for solar-thermal parabolic-dish systems  

SciTech Connect

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. A 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. Results indicate that the near-term market for such systems depends not only on the type of crop and method of irrigation, but also on the optimal utilization of each added module, which in turn depends on the price of conventional fuel, real discount rate, marginal cost of the solar thermal power system, local insolation level and parabolic dish system efficiency. The study concludes that the potential market size for onfarm-pumped irrigation applications ranges from 101,000 modules when a 14% real discount rate is assumed to 220,000 modules when the real discount rate drops to 8%. Arizona, Kansas, Nebraska, New Mexico and Texas account for 98% of the total demand for this application, with the natural gas replacement market accounting for the largest segment (71%) of the total market.

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

1981-09-01

32

Thermal storage requirements for parabolic dish solar power plants  

NASA Technical Reports Server (NTRS)

The cost effectiveness of a high temperature thermal storage system is investigated for a representative parabolic dish solar power plant. The plant supplies electrical power in accordance with a specific, seasonally varying demand profile. The solar power received by the plant is supplemented by power from fuel combustion. The cost of electricity generated by the solar power plant is calculated, using the cost of mass-producible subsystems (specifically, parabolic dishes, receivers, and power conversion units) now being designed for this type of solar plant. The trade-off between fuel and thermal storage is derived in terms of storage effectiveness, the cost of storage devices, and the cost of fuel. Thermal storage requirements, such as storage capacity, storage effectiveness, and storage cost are established based on the cost of fuel and the overall objective of minimizing the cost of the electricity produced by the system. As the cost of fuel increases at a rate faster than general inflation, thermal storage systems in the $40 to $70/kWthr range could become cost effective in the near future.

Wen, L.; Steele, H.

1980-01-01

33

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

34

Novel second-stage solar concentrator for parabolic troughs  

NASA Astrophysics Data System (ADS)

Conventional parabolic troughs can be combined with second stage concentrators (SSC), to increase temperature and pressure inside the absorber, making possible the direct production of steam, improving substantially the overall system efficiency and leading to a new generation of distributed solar power plants. To attain this objective, research is needed at the optical, thermodynamic, system control, and engineering levels. In what concerns the receiver of such a system, different practical solutions have been proposed recently and in the past for the geometry of the second stage concentrator: CPC type and others. In this work we discuss these solutions and we propose a new one, 100% efficient in energy collection while reaching a total concentration ratio which is almost 65% of the thermodynamic limit. This SSC has an asymmetric elliptical geometry, rendering possible a smooth solution for the reflectors while maintaining a reasonable size for the receiver.

Collares-Pereira, Manuel; Mendes, Joao F.

1995-08-01

35

Mechanical development of the actuation system of a parabolic solar trough  

E-print Network

This thesis documents my personal contribution to the engineering and design of an actuation system with the purpose of rotating a parabolic solar trough to track the sun throughout the day. The primary focus of the design ...

O'Rourke, Conor R. (Conor Rakis)

2011-01-01

36

The parabolic trough power plants Andasol 1 to 3 The largest solar power plants in the world  

E-print Network

The parabolic trough power plants Andasol 1 to 3 The largest solar power plants in the world and solar-thermal power plants The first parabolic trough power plants in Europe ­ the world's largest solar power plants: Andasol 1 to 3 Regulatory framework in Spain Project partners 4 8 20 22 #12;4 Solar energy

Laughlin, Robert B.

37

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

38

Guidelines for reporting parabolic trough solar electric system performance  

SciTech Connect

The purpose of this activity is to develop a generic methodology which can be used to track and compare the performance of parabolic trough power plants. The approach needs to be general enough to work for all existing and future parabolic trough plant designs, provide meaningful comparisons of year to year performance, and allow for comparisons between dissimilar plant designs. The approach presented here uses the net annual system efficiency as the primary metric for evaluating the performance of parabolic trough power plants. However, given the complex nature of large parabolic trough plants, the net annual system efficiency by itself does not adequately characterize the performance of the plant. The approach taken here is to define a number of additional performance metrics which enable a more comprehensive understanding of overall plant performance.

Price, H.W.

1997-06-01

39

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

40

Assessment of a Molten Salt Heat Transfer Fluid in a Parabolic Trough Solar Field  

Microsoft Academic Search

An evaluation was carried out to investigate the feasibility of utilizing a molten salt as the heat transfer fluid (HTF) and for thermal storage in a parabolic trough solar field to improve system performance and to reduce the levelized electricity cost. The operating SEGS1 plants currently use a high temperature synthetic oil consisting of a eutectic mixture of biphenyl\\/diphenyl oxide.

D. Kearney; U. Herrmann; P. Nava; B. Kelly; R. Mahoney; J. Pacheco; R. Cable; N. Potrovitza; D. Blake; H. Price

2003-01-01

41

Enhanced irradiance distribution on solar cell using optimized variable-focus-parabolic concentrator  

NASA Astrophysics Data System (ADS)

A solar cell concentrator system is proposed comprising a square solar cell and a variable-focus-parabolic (VFP) reflector in which the focal length varies as a function of the horizontal displacement of the incidence point relative to the vertical centerline of the solar cell. The light ray paths within the concentrator system are analyzed using an exact analytical model and a skew-ray tracing approach. The geometry of the VFP reflector is then optimized in such a way as to maximize the uniformity of the irradiance distribution on the solar cell given a circular focus spot and a square focus spot, respectively. The effectiveness of the optimized VFP reflector with a square focus spot is investigated by means of ZEMAX simulations. It is shown that the optimized VFP concentrator yields a significant improvement in the irradiance uniformity compared to that achieved using a conventional parabolic concentrator.

Tsai, Chung-Yu

2013-09-01

42

Use of parabolic trough solar energy collectors for sea-water desalination  

Microsoft Academic Search

The various desalination methods are analysed with respect to their primary energy consumption, sea-water treatment requirement and equipment cost. From this analysis, the multiple-effect boiling evaporator is concluded to be the most suitable method for stimulation by solar energy. The parabolic-trough solar-collector is selected mainly due to its ability to function at high temperatures with high efficiency. The design of

Soteris Kalogirou

1998-01-01

43

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

NASA Astrophysics Data System (ADS)

The potential performance of single-axis tracking parabolic trough solar collectors as a function of optical energy distribution and receiver size was 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 thermo-optical tradeoffs. The capability of the thermo-optical model was 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.

1980-03-01

44

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

45

A Linear Parabolic Trough Solar Collector Performance Model  

E-print Network

Collector (PTSC). This steady state, single dimensional model comprises the fundamental radiative and convective heat transfer and mass and energy balance relations programmed in the Engineering Equation Solver, EES. It considers the effects of solar...

Qu, M.; Archer, D.; Masson, S.

2006-01-01

46

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

NASA Astrophysics Data System (ADS)

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 mass producible collector design suitable for operation at 250 to 450 F. The key criterion for optimization of the design was minimization of the cost per Btu collected annually at an operating temperature of 400 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.

Ballheim, R. W.

1980-04-01

47

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

48

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

Microsoft Academic Search

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,

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

1982-01-01

49

Concentrating Solar Power, Seawater Desalination, Parabolic Troughs, Fresnel Systems  

Microsoft Academic Search

Today's conflicts on oil are tomorrow's conflicts on water has become a popular issue to describe the enduring water and energy crisis, although solution for both energy and water shortage seems to be on hand: Making power and water from sun and sea. Concentrating solar power (CSP) offers a sustainable alternative to fossil fuels for large scale seawater desalination. CSP

V. K. SethiE; Mukesh Pandey; Priti Shukla; R. G. P. V. Bhopal

2012-01-01

50

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

51

Fast Food with Slow Cookers SESSION GOALS  

E-print Network

Fast Food with Slow Cookers SESSION GOALS: Participants will learn how to use a slow cooker to help survey instrument (if needed) #12;2 Fast Food with Slow Cookers BEFORE THIS SESSION: 1. Review materials created by Cornell University Cooperative Extension. #12;3 Fast Food with Slow Cookers SESSION 1

52

Analysis of Conduction Heat Loss From a Parabolic Trough Solar Receiver with Active Vacuum by Direct Simulation Monte Carlo  

Microsoft Academic Search

Results are reported of a numerical analysis of conduction heat loss from a parabolic trough solar receiver with controlled pressure within the annular gap between the tubular absorber and the glass vacuum jacket. A direct simulation Monte Carlo (DSMC)model of rarefied gas within the annular gap is coupled to radiation heat transfer for directional- and spectral-dependent concentrated incident solar radiation.

Matthew Roesle; Philipp Good; Volkan Coskun; Aldo Steinfeld

2012-01-01

53

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

54

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

55

Development, solar test, and evaluation of a high-temperature air receiver for point-focusing parabolic dish applications  

Microsoft Academic Search

A high temperature solar receiver was fabricated and tested in excess of 1370 C on an 11-meter-diameter test bed concentrator at the Jet Propulsion Laboratory Parabolic Dish Test Site, Edwards, California. The 60-kilowatt thermal receiver design utilizes state-of-the-art silicon carbide honeycomb matrix panels to receive and transfer the solar energy and mullite elements for thermal buffer storage. Solar tests were

E. J. Hanseth

1981-01-01

56

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

57

Thermal Modeling of a Hybrid Thermoelectric Solar Collector with a Compound Parabolic Concentrator  

NASA Astrophysics Data System (ADS)

In this study radiant light from the sun is used by a hybrid thermoelectric (TE) solar collector and a compound parabolic concentrator (CPC) to generate electricity and thermal energy. The hybrid TE solar collector system described in this report is composed of transparent glass, an air gap, an absorber plate, TE modules, a heat sink to cool the water, and a storage tank. Incident solar radiation falls on the CPC, which directs and reflects the radiation to heat up the absorber plate, creating a temperature difference across the TE modules. The water, which absorbs heat from the hot TE modules, flows through the heat sink to release its heat. The results show that the electrical power output and the conversion efficiency depend on the temperature difference between the hot and cold sides of the TE modules. A maximum power output of 1.03 W and a conversion efficiency of 0.6% were obtained when the temperature difference was 12C. The thermal efficiency increased as the water flow rate increased. The maximum thermal efficiency achieved was 43.3%, corresponding to a water flow rate of 0.24 kg/s. These experimental results verify that using a TE solar collector with a CPC to produce both electrical power and thermal energy seems to be feasible. The thermal model and calculation method can be applied for performance prediction.

Lertsatitthanakorn, C.; Jamradloedluk, J.; Rungsiyopas, M.

2013-07-01

58

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

59

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

60

Comparison of electrochemical and thermal storage for hybrid parabolic dish solar power plants  

NASA Technical Reports Server (NTRS)

The economic and operating performance of a parabolic point focus array of solar electricity generators combined with either battery or thermal energy storage are examined. Noting that low-cost, mass-producible power generating units are under development for the point focus of distributed dishes, that Zn-Cl battery tests will begin in 1981 and a 100 kWh Na-S battery in 1983, the state of thermal storage requires acceleration to reach the prototype status of the batteries. Under the assumptions of 10,000 units/yr with an expected 30 yr lifetime, cost comparisons are developed for 10 types of advanced batteries. A 5 MWe plant with full thermal or 80% battery storage discharge when demand occurs in conditions of no insolation is considered, specifically for Fe-Cr redox batteries. A necessity for the doubling of fuel prices from 1980 levels by 1990 is found in order to make the systems with batteries economically competitive.

Steele, H. L.; Wen, L.

1981-01-01

61

Development of Performance Acceptance Test Guidelines for Large Commercial Parabolic Trough Solar Fields: Preprint  

SciTech Connect

Prior to commercial operation, large solar systems in utility-size power plants need to pass a performance acceptance test conducted by the EPC contractor or owners. In lieu of the present absence of engineering code developed for this purpose, NREL 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 fundamental differences between acceptance of a solar power plant and a conventional fossil-fired plant are the transient nature of the energy source and the necessity to utilize an analytical performance model in the acceptance process. These factors bring into play the need to establish methods to measure steady state performance, potential impacts of transient processes, comparison to performance model results, and the possible requirement to test, or model, multi-day performance within the scope of the acceptance test procedure. The power block and BOP are not within the boundaries of this guideline. The current guideline is restricted to the solar thermal performance of parabolic trough systems and has been critiqued by a broad range of stakeholders in CSP development and technology.

Kearney, D.; Mehos, M.

2010-12-01

62

An Optical Characterization Technique for Parabolic Trough Solar Collectors Using Images of the Absorber Reflection  

NASA Astrophysics Data System (ADS)

As the concentrating solar power industry competes to develop a less-expensive parabolic trough collector, assurance is needed that new parabolic trough collectors maintain accurate optical alignment. Previous optical characterization techniques are either too slow, ill-suited for field testing, or do not allow the collector to be tested in realistic orientations. The Observer method presented here enables the rapid optical characterization of parabolic trough collectors in any orientation in the field. The Observer method directly measures the combined optical angular errors in the reflector surface shape and the absorber position, which can be separated into its two components: reflector surface slope and absorber misalignment. The data acquisition requires the placement of photogrammetry targets on and around the collector. Multiple photographs of the absorber and its reflection are taken with a digital camera from different angles with respect to the collector. The images are processed to determine the camera location of each image using photogrammetry bundle analysis. The absorber and its reflection are found in the photographs using image-processing techniques. A Monte Carlo uncertainty model was developed to determine the uncertainty in the Observer measurements. The uncertainty was estimated for a wide array of measurement test scenarios to demonstrate the user's control over the measurement uncertainty. To validate the Observer method, the absorber alignment technique was compared to traditional photogrammetry; the absorber position measured with the two methods compared with a root-mean-square difference of 1.5 mm in the transverse direction and 0.86 mm along the optical axis. The reflector surface slope error measurement was compared to both VSHOT and SOFAST, two well-established optical characterization tools, by measuring a single reflector panel in the laboratory. The VSHOT and SOFAST measurements agreed with the Observer with a root-mean-square difference of 1.6 mrad and 2.1 mrad, respectively. In the field, the Observer method's capability to test collectors in any orientation was demonstrated by mounting the camera on a radio-controlled helicopter and measuring a collector oriented at 90 above the horizon. The absorber measurement capability was demonstrated in the field for a collector facing both horizontally and vertically.

Owkes, Jeanmarie Kathleen

63

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

64

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

65

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

66

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

67

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

68

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.

69

Numerical study on coupled fluid flow and heat transfer process in parabolic trough solar collector tube  

SciTech Connect

A unified two-dimensional numerical model was developed for the coupled heat transfer process in parabolic solar collector tube, which includes nature convection, forced convection, heat conduction and fluid-solid conjugate problem. The effects of Rayleigh number (Ra), tube diameter ratio and thermal conductivity of the tube wall on the heat transfer and fluid flow performance were numerically analyzed. The distributions of flow field, temperature field, local Nu and local temperature gradient were examined. The results show that when Ra is larger than 10{sup 5}, the effects of nature convection must be taken into account. With the increase of tube diameter ratio, the Nusselt number in inner tube (Nu{sub 1}) increases and the Nusselt number in annuli space (Nu{sub 2}) decreases. With the increase of tube wall thermal conductivity, Nu{sub 1} decreases and Nu{sub 2} increases. When thermal conductivity is larger than 200 W/(m K), it would have little effects on Nu and average temperatures. Due to the effect of the nature convection, along the circumferential direction (from top to down), the temperature in the cross-section decreases and the temperature gradient on inner tube surface increases at first. Then, the temperature and temperature gradients would present a converse variation at {theta} near {pi}. The local Nu on inner tube outer surface increases along circumferential direction until it reaches a maximum value then it decreases again. (author)

Tao, Y.B.; He, Y.L. [State Key Laboratory of Multiphase Flow in Power Engineering, School of Energy and Power Engineering, Xi'an Jiaotong University, Xi'an, Shaanxi 710049 (China)

2010-10-15

70

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

71

High concentration two-stage optics for parabolic trough solar collectors with tubular absorber and large rim angle  

SciTech Connect

A new two-stage optical design is proposed for parabolic trough solar collectors with tubular absorbers. It can boost the concentration ratio by a factor of 2.5 relative to the conventional design, while maintaining the large rim angles (i.e., low nominal f-numbers) that are desirable for practical and economical reasons. The second state involves asymmetric nonimaging concentrators of the CPC type, facing segments of the parabolic first stage. The second stage can be accommodated inside an evacuated receiver, allowing the use of first-surface silvered reflectors. The low heat loss of this design opens the possibility of producing steam at temperatures and pressures of conventional power plants, using only one-axis tracking. The improvement in conversion efficiency would be substantial.

Collares-Pereira, M. (Centro para a Conservacao de Energia, Amadora (Portugal)); Gordon, J.M. (Ben Gurion Univ. of the Negev, Beersheva (Israel)); Rabl, A. (Centre d'Energetique, Paris (France)); Winston, R. (Univ. of Chicago, IL (United States))

1991-01-01

72

Comparison of Fresnel lenses and parabolic mirrors as solar energy concentrators  

SciTech Connect

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 lower than that obtained using a curved lens.

Lorenzo, E.; Luque, A.

1982-05-15

73

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

74

Economic analysis of power generation from parabolic trough solar thermal plants for the Mediterranean regionA case study for the island of Cyprus  

Microsoft Academic Search

In this work a feasibility study is carried out in order to investigate whether the installation of a parabolic trough solar thermal technology for power generation in the Mediterranean region is economically feasible. The case study takes into account the available solar potential for Cyprus, as well as all available data concerning current renewable energy sources policy of the Cyprus

Andreas Poullikkas

2009-01-01

75

Development, solar test, and evaluation of a high-temperature air receiver for point-focusing parabolic dish applications  

NASA Astrophysics Data System (ADS)

A high temperature solar receiver was fabricated and tested in excess of 1370 C on an 11-meter-diameter test bed concentrator at the Jet Propulsion Laboratory Parabolic Dish Test Site, Edwards, California. The 60-kilowatt thermal receiver design utilizes state-of-the-art silicon carbide honeycomb matrix panels to receive and transfer the solar energy and mullite elements for thermal buffer storage. Solar tests were conducted with indicated air exit temperatures ranging from 885 C (1625 F) to 1427 C (2600 F), mass flow rates of 75 to 105 g/sec (0.16 to 0.23 lbm/sec), and pressures up to 265 kPa absolute (38.4 psia). Estimates of efficiency are 59.7% at 1120 C (2048 F) to 80.6% at 885 C (1625 F) when aperture spillage losses are considered separately. Results are presented which demonstrate the feasibility of this innovative receiver concept for point-focusing parabolic dish applications over a wide temperature range.

Hanseth, E. J.

1981-12-01

76

Development, solar test, and evaluation of a high-temperature air receiver for point-focusing parabolic dish applications  

NASA Technical Reports Server (NTRS)

A high temperature solar receiver was fabricated and tested in excess of 1370 C on an 11-meter-diameter test bed concentrator at the Jet Propulsion Laboratory Parabolic Dish Test Site, Edwards, California. The 60-kilowatt thermal receiver design utilizes state-of-the-art silicon carbide honeycomb matrix panels to receive and transfer the solar energy and mullite elements for thermal buffer storage. Solar tests were conducted with indicated air exit temperatures ranging from 885 C (1625 F) to 1427 C (2600 F), mass flow rates of 75 to 105 g/sec (0.16 to 0.23 lbm/sec), and pressures up to 265 kPa absolute (38.4 psia). Estimates of efficiency are 59.7% at 1120 C (2048 F) to 80.6% at 885 C (1625 F) when aperture spillage losses are considered separately. Results are presented which demonstrate the feasibility of this innovative receiver concept for point-focusing parabolic dish applications over a wide temperature range.

Hanseth, E. J.

1981-01-01

77

7 CFR 58.709 - Cookers.  

Code of Federal Regulations, 2013 CFR

...They shall be constructed of stainless steel or other equally corrosion-resistant...cooker wall, be constructed of stainless steel and designed to prevent the...line shall be constructed of stainless steel pipes and fittings which...

2013-01-01

78

7 CFR 58.709 - Cookers.  

...They shall be constructed of stainless steel or other equally corrosion-resistant...cooker wall, be constructed of stainless steel and designed to prevent the...line shall be constructed of stainless steel pipes and fittings which...

2014-01-01

79

7 CFR 58.709 - Cookers.  

Code of Federal Regulations, 2010 CFR

...They shall be constructed of stainless steel or other equally corrosion-resistant...cooker wall, be constructed of stainless steel and designed to prevent the...line shall be constructed of stainless steel pipes and fittings which...

2010-01-01

80

7 CFR 58.709 - Cookers.  

Code of Federal Regulations, 2012 CFR

...They shall be constructed of stainless steel or other equally corrosion-resistant...cooker wall, be constructed of stainless steel and designed to prevent the...line shall be constructed of stainless steel pipes and fittings which...

2012-01-01

81

7 CFR 58.709 - Cookers.  

Code of Federal Regulations, 2011 CFR

...They shall be constructed of stainless steel or other equally corrosion-resistant...cooker wall, be constructed of stainless steel and designed to prevent the...line shall be constructed of stainless steel pipes and fittings which...

2011-01-01

82

Solar Cooking. What We Make. Science and Technology Education in Philippine Society.  

ERIC Educational Resources Information Center

This module is designed to help students: (1) describe a way of tapping solar energy; (2) identify the main parts of a box type solar cooker; (3) describe how each part contributes to the trapping of heat energy in the cooker; (4) cook some food in a solar cooker; and (5) recognize that food cooked in a solar cooker is safe to eat. It includes: an

Philippines Univ., Quezon City. Inst. for Science and Mathematics Education Development.

83

Performance evaluation and simulation of a Compound Parabolic Concentrator (CPC) trough Solar Thermal Power Plant in Puerto Rico under solar transient conditions  

NASA Astrophysics Data System (ADS)

The increasing fossil fuel costs as well as the need to move in a somewhat sustainable future has led the world in a quest for exploiting the free and naturally available energy from the Sun to produce electric power, and Puerto Rico is no exception. This thesis proposes the design of a simulation model for the analysis and performance evaluation of a Solar Thermal Power Plant in Puerto Rico and suggests the use of the Compound Parabolic Concentrator as the solar collector of choice. Optical and thermal analysis of such collectors will be made using local solar radiation data for determining the viability of this proposed project in terms of the electric power produced and its cost.

Feliciano-Cruz, Luisa I.

84

Advances in solar energy technology. Volume 3. Heating, agricultural and photovoltaic applications of solar energy  

SciTech Connect

This volume discusses the heating, agricultural and photovoltaic applications of solar energy, and contains the following chapters, solar cookers, solar desalination, solar food drying, solar-powered water pumps, solar greenhouses, solar cells.

Garg, H.P.

1987-01-01

85

An analysis of the technical and economic performance of a parabolic trough concentrator for solar industrial process heat application  

NASA Astrophysics Data System (ADS)

Design parameters and economic projections of importance to the commercial realization of mass-produced parabolic trough solar concentrators as industrial heat suppliers are presented. Numerical formulas are defined for obtaining a figure of merit for the thermal efficiency of a concentrator, taking into account the reflectivity, the mirror-receiver intercept factor, the end loss factor, tracking and misalignment errors, the absorptivity-transmissivity product at normal incidence of the receiver tube and its glass envelope, and durability. An economic analysis which includes all costs, tax write-offs, comparisons with conventional fuels, inflation rate, time of borrowing, maintenance, profits, and conversion efficiencies is developed. It was determined that the trough systems will become competitive in the U.S. when installed costs are $15.79/sq ft over a 10-yr investment period

Clark, J. A.

1982-09-01

86

Simulation of a photo-solar generator for an optimal output by a parabolic photovoltaic concentrator of Stirling engine type  

NASA Astrophysics Data System (ADS)

Solar energy is the source of the most promising energy and the powerful one among renewable energies. Photovoltaic electricity (statement) is obtained by direct transformation of the sunlight into electricity, by means of cells statement. Then, we study the operation of cells statement by the digital simulation with an aim of optimizing the output of the parabolic concentrator of Stirling engine type. The Greenius software makes it possible to carry out the digital simulation in 2D and 3D and to study the influence of the various parameters on the characteristic voltage under illumination of the cell. The results obtained enabled us to determine the extrinsic factors which depend on the environment and the intrinsic factors which result from the properties of materials used.

Kaddour, A.; Benyoucef, B.

87

Feasibility Study on the Use of a Solar Thermoelectric Cogenerator Comprising a Thermoelectric Module and Evacuated Tubular Collector with Parabolic Trough Concentrator  

NASA Astrophysics Data System (ADS)

We have designed a new solar thermoelectric cogeneration system consisting of an evacuated tubular solar collector (ETSC) with a parabolic trough concentrator (PTC) and thermoelectric modules (TEMs) to supply both thermal energy and electricity. The main design concepts are (1) the hot side of the TEM is bonded to the solar selective absorber installed in an evacuated glass tube, (2) the cold side of the TEM is also bonded to the heat sink, and (3) the outer circulated water is heated by residual solar energy after TEM generation. We present an example solar thermal simulation based on energy balance and heat transfer as used in solar engineering to predict the electrical conversion efficiency and solar thermal conversion efficiency for different values of parameters such as the solar insolation, concentration ratio, and TEM ZT values.

Miao, L.; Zhang, M.; Tanemura, S.; Tanaka, T.; Kang, Y. P.; Xu, G.

2012-06-01

88

Two-tank molten salt storage for parabolic trough solar power plants  

Microsoft Academic Search

The most advanced thermal energy storage for solar thermal power plants is a two-tank storage system where the heat transfer fluid (HTF) also serves as storage medium. This concept was successfully demonstrated in a commercial trough plant (13.8 MWe SEGS I plant; 120 MWht storage capacity) and a demonstration tower plant (10 MWe Solar Two; 105 MWht storage capacity). However,

Ulf Herrmann; Bruce Kelly; Henry Price

2004-01-01

89

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

90

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

91

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

92

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

93

Preliminary study on optimization of pH, oxidant and catalyst dose for high COD content: solar parabolic trough collector  

PubMed Central

In the present study, solar photocatalytic oxidation has been investigated through laboratory experiments as an alternative to conventional secondary treatment for the organic content reduction of high COD wastewater. Experiments have been performed on synthetic high COD wastewater for solar photocatalytic oxidation using a parabolic trough reactor. Parameters affecting the oxidation of organics have been investigated. The experimental design followed the sequence of dark adsorption studies of organics, followed by photolytic studies (in absence of catalyst) and finally photocatalytic studies in presence and absence of additional oxidant (H2O2). All the experimental studies have been performed at pH values of 2, 4, 6,8,10 and the initial pH value of the wastewater (normal pH). For photocatalytic studies, TiO2 has been used as a photocatalyst. Optimization of catalyst dose, pH and H2O2 concentration has been done. Maximum reduction of organic content was observed at the normal pH value of the wastewater (pH?=?6.8). The reaction rate was significantly enhanced in presence of hydrogen peroxide. The optimum pH other than the Normal was in the alkaline range. Acidic pH was not found to be favourable for organic content reduction. pH was found to be a dominant factor affecting reaction rate even in presence of H2O2 as an additional oxidant. Also, the solar detoxification process was effective in treating a waste with a COD level of more than 7500 mg/L, which is a otherwise a difficult waste to treat. It can therefore be used as a treatment step in the high organic wastewater treatment during the primary stage also as it effectively reduces the COD content by 86%. PMID:23369352

2013-01-01

94

Preliminary thermoeconomic analysis of combined parabolic trough solar power and desalination plant in port Safaga (Egypt)  

Microsoft Academic Search

The development of society is strongly dependent on water and electricity. There is an increasing water and energy demand driven by population growth and rising industrial and agricultural production. The combination of concentrated solar power (CSP) and desalination processes has a huge potential for producing both energy and water in arid regions suffering from fresh water scarcity and facing the

J. Blanco; P. Palenzuela; D. Alarcn-Padilla; G. Zaragoza; M. Ibarra

2012-01-01

95

Evaluation of the Solar Water Disinfection Process (SODIS) Against Cryptosporidium parvum Using a 25-L Static Solar Reactor Fitted with a Compound Parabolic Collector (CPC)  

PubMed Central

Water samples of 0, 5, and 30 nephelometric turbidity units (NTU) spiked with Cryptosporidium parvum oocysts were exposed to natural sunlight using a 25-L static solar reactor fitted with a compound parabolic collector (CPC). The global oocyst viability was calculated by the evaluation of the inclusion/exclusion of the fluorogenic vital dye propidium iodide and the spontaneous excystation. After an exposure time of 8 hours, the global oocyst viabilities were 21.8 3.1%, 31.3 12.9%, and 45.0 10.0% for turbidity levels of 0, 5, and 30 NTU, respectively, and these values were significantly lower (P < 0.05) that the initial global viability of the isolate (92.1 0.9%). The 25-L static solar reactor that was evaluated can be an alternative system to the conventional solar water disinfection process for improving the microbiological quality of drinking water on a household level, and moreover, it enables treatment of larger volumes of water (> 10 times). PMID:22302852

Fontan-Sainz, Maria; Gomez-Couso, Hipolito; Fernandez-Ibanez, Pilar; Ares-Mazas, Elvira

2012-01-01

96

Life cycle assessment of a parabolic trough concentrating solar power plant and the impacts of key design alternatives.  

PubMed

Climate change and water scarcity are important issues for today's power sector. To inform capacity expansion decisions, hybrid life cycle assessment is used to evaluate a reference design of a parabolic trough concentrating solar power (CSP) facility located in Daggett, CA, along four sustainability metrics: life cycle (LC) greenhouse gas (GHG) emissions, water consumption, cumulative energy demand (CED), and energy payback time (EPBT). This wet-cooled, 103 MW plant utilizes mined nitrates salts in its two-tank, thermal energy storage (TES) system. Design alternatives of dry-cooling, a thermocline TES, and synthetically derived nitrate salt are evaluated. During its LC, the reference CSP plant is estimated to emit 26 g of CO(2eq) per kWh, consume 4.7 L/kWh of water, and demand 0.40 MJ(eq)/kWh of energy, resulting in an EPBT of approximately 1 year. The dry-cooled alternative is estimated to reduce LC water consumption by 77% but increase LC GHG emissions and CED by 8%. Synthetic nitrate salts may increase LC GHG emissions by 52% compared to mined. Switching from two-tank to thermocline TES configuration reduces LC GHG emissions, most significantly for plants using synthetically derived nitrate salts. CSP can significantly reduce GHG emissions compared to fossil-fueled generation; however, dry-cooling may be required in many locations to minimize water consumption. PMID:21391722

Burkhardt, John J; Heath, Garvin A; Turchi, Craig S

2011-03-15

97

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

98

Wind effects on convective heat loss from a cavity receiver for a parabolic concentrating solar collector  

SciTech Connect

Tests were performed to determine the convective heat loss characteristics of a cavity receiver for a parabolid dish concentrating solar collector for various tilt angles and wind speeds of 0-24 mph. Natural (no wind) convective heat loss from the receiver is the highest for a horizontal receiver orientation and negligible with the reveler facing straight down. Convection from the receiver is substantially increased by the presence of side-on wind for all receiver tilt angles. For head-on wind, convective heat loss with the receiver facing straight down is approximately the same as that for side-on wind. Overall it was found that for wind speeds of 20--24 mph, convective heat loss from the receiver can be as much as three times that occurring without wind.

Ma, R.Y. [California State Polytechnic Univ., Pomoma, CA (United States). Dept. of Mechanical Engineering

1993-09-01

99

Design, construction and study of a hybrid solar food processor in the climate of Costa Rica  

Microsoft Academic Search

During the last 25 years, the author has designed, constructed, studied and promoted solar oven, hybrid solar\\/electric oven, solar oven cum drier, solar cooker cum water heater and solar still. In different parts of the world, solar cookers have been made, studied, patented, however, their real uses are very limited due to many reasonsunstable climate, economic, cultural, social and single

Shyam S. Nandwani

2007-01-01

100

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

101

Manufacturing cost analysis of a parabolic dish concentrator (General Electric design) for solar thermal electric power systems in selected production volumes  

NASA Technical Reports Server (NTRS)

The manufacturing cost of a General Electric 12 meter diameter concentrator was estimated. This parabolic dish concentrator for solar thermal system was costed in annual production volumes of 100 - 1,000 - 5,000 - 10,000 - 50,000 100,000 - 400,000 and 1,000,000 units. Presented for each volume are the costs of direct labor, material, burden, tooling, capital equipment and buildings. Also presented is the direct labor personnel and factory space requirements. All costs are based on early 1981 economics.

1981-01-01

102

Smart ultrasonic device for vitro-ceramic cooker safety control  

Microsoft Academic Search

This paper describes a safety device for the automatic regulation of the power of vitro ceramic cookers. The system is based on an ultrasound sensor for presence detection and proximity measurement. The sensor detects the presence or absence of an object on the heat sources of the cooker. Once the object is taken away from the burner, the system starts

A. Lazaro; I. Serrano; F. J. Guardado; R. Herrero

1999-01-01

103

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

104

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

NASA Astrophysics Data System (ADS)

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.

1988-11-01

105

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

106

Testing thermocline filler materials and molten-salt heat transfer fluids for thermal energy storage systems used in parabolic trough solar power plants.  

SciTech Connect

Parabolic trough power systems that utilize concentrated solar energy to generate electricity are a proven technology. Industry and laboratory research efforts are now focusing on integration of thermal energy storage as a viable means to enhance dispatchability of concentrated solar energy. One option to significantly reduce costs is to use thermocline storage systems, low-cost filler materials as the primary thermal storage medium, and molten nitrate salts as the direct heat transfer fluid. Prior thermocline evaluations and thermal cycling tests at the Sandia National Laboratories' National Solar Thermal Test Facility identified quartzite rock and silica sand as potential filler materials. An expanded series of isothermal and thermal cycling experiments were planned and implemented to extend those studies in order to demonstrate the durability of these filler materials in molten nitrate salts over a range of operating temperatures for extended timeframes. Upon test completion, careful analyses of filler material samples, as well as the molten salt, were conducted to assess long-term durability and degradation mechanisms in these test conditions. Analysis results demonstrate that the quartzite rock and silica sand appear able to withstand the molten salt environment quite well. No significant deterioration that would impact the performance or operability of a thermocline thermal energy storage system was evident. Therefore, additional studies of the thermocline concept can continue armed with confidence that appropriate filler materials have been identified for the intended application.

Kelly, Michael James; Hlava, Paul Frank; Brosseau, Douglas A.

2004-07-01

107

Instability of induction cooker (electromagnetic stove) antigen retrieval in immunohistochemistry.  

PubMed

An induction cooker is a modern electric cooker that takes electromagnetic induction principle to heat. As it has high efficiency, no open flame, and is safe and convenient, more and more laboratories use it as an antigen retrieval heating tool in immunohistochemistry. We found that there was still some instability with the induction cooker, because with certain antigens the power change influenced the results of immunohistochemistry staining, showing weaker staining intensity or decreased number of positive cells, but which were not entirely negative. For some antigens, it had no influence on results. The instability of this heating tool for antigen retrieval was caused partly by negligent operators, and which may influence the experimental results and the pathologic diagnosis. PMID:19247182

Ding, Wei; Zheng, Xiang-Yi

2012-03-01

108

Assessment of different configurations for combined parabolic-trough (PT) solar power and desalination plants in arid regions  

Microsoft Academic Search

The combination of desalination technology into concentrating solar power (CSP) plants needs to be considered for the planned installation of CSP plants in arid regions. There are interesting synergies between the two technologies, like the possibility of substituting the condenser of the power cycle for a thermal desalination unit. This paper presents a thermodynamic evaluation of different configurations for coupling

Patricia Palenzuela; Guillermo Zaragoza; Diego C. Alarcn-Padilla; Elena Guilln; Mercedes Ibarra; Julin Blanco

2011-01-01

109

Simulation and evaluation of the coupling of desalination units to parabolic-trough solar power plants in the Mediterranean region  

Microsoft Academic Search

Integrated power and desalination plants (IPDP) may provide a key solution for the pressing freshwater deficit and energy problems in many regions of the world. The current study investigates the potential of low-temperature multi-effect distillation (LT-MED) and thermal vapor compression multi-effect distillation (TVC-MED) coupled with a concentrating solar power (CSP) plant, taking also into account a reverse osmosis (RO) unit

Patricia Palenzuela; Guillermo Zaragoza; Diego Alarcn; Julin Blanco

2011-01-01

110

Comparison between periodic and stochastic parabolic light trapping structures for thin-film microcrystalline Silicon solar cells.  

PubMed

Light trapping is of very high importance for silicon photovoltaics (PV) and especially for thin-film silicon solar cells. In this paper we investigate and compare theoretically the light trapping properties of periodic and stochastic structures having similar geometrical features. The theoretical investigations are based on the actual surface geometry of a scattering structure, characterized by an atomic force microscope. This structure is used for light trapping in thin-film microcrystalline silicon solar cells. Very good agreement is found in a first comparison between simulation and experimental results. The geometrical parameters of the stochastic structure are varied and it is found that the light trapping mainly depends on the aspect ratio (length/height). Furthermore, the maximum possible light trapping with this kind of stochastic structure geometry is investigated. In a second step, the stochastic structure is analysed and typical geometrical features are extracted, which are then arranged in a periodic structure. Investigating the light trapping properties of the periodic structure, we find that it performs very similar to the stochastic structure, in agreement with reports in literature. From the obtained results we conclude that a potential advantage of periodic structures for PV applications will very likely not be found in the absorption enhancement in the solar cell material. However, uniformity and higher definition in production of these structures can lead to potential improvements concerning electrical characteristics and parasitic absorption, e.g. in a back reflector. PMID:23388775

Peters, M; Battaglia, C; Forberich, K; Blsi, B; Sahraei, N; Aberle, A G

2012-12-31

111

Solar Cooking in the Sahel1 Beth Newton1  

E-print Network

in North and West Africa. Solar cookers could be widely used, an average36 of about 90% of days in some a cardboard panel and a dark cooking pot45 contained in a clear plastic bag to retain the warm air. Such a cooker can cook even dried46 food in less than three hours as long as sunshine is available, allowing

Marsham, John

112

Resonance in a model for Cooker's sloshing experiment  

E-print Network

Resonance in a model for Cooker's sloshing experiment -- the extended version -- by H. Alemi that they are equivalent. The most important observation is the discovery of an internal 1 : 1 resonance both are coupled to the vessel motion. Numerical evaluation of the resonant and nonresonant modes are presented

Bridges, Tom

113

Solar-parabolic dish-Stirling-engine-system module. Task 1: Topical report, market assessment/conceptual design  

SciTech Connect

The major activities reported are: a market study to identify an early market for a dish-Stirling module and assess its commercial potential; preparation of a conceptual system and subsystem design to address this market; and preparation of an early sales implementation plan. A study of the reliability of protection from the effects of walk-off, wherein the sun's image leaves the receiver if the dish is not tracking, is appended, along with an optical analysis and structural analysis. Also appended are the relationship between PURPA and solar thermal energy development and electric utility pricing rationale. (LEW)

Not Available

1982-11-30

114

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

115

Multi-scale and angular analysis of ray-optical light trapping schemes in thin-film solar cells: micro lens array, V-shaped configuration, and double parabolic trapper.  

PubMed

An efficient light trapping scheme is a key to enhancing the power conversion efficiency (PCE) of thin-film photovoltaic (PV) cells by compensating for the insufficient light absorption. To handle optical components from nano-scale to micro-scale seamlessly, a multi-scale optical simulation is carefully designed in this study and is used to qualitatively analyze the light trapping performances of a micro lens array (MLA), a V-shaped configuration, and the newly proposed scheme, which is termed a double parabolic trapper (DPT) according to both daily and annual movement of the sun. DPT has the potential to enhance the PCE significantly, from 5.9% to 8.9%, for PCDTBT:PC(70)BM-based polymer solar cells by perfectly trapping the incident light between two parabolic PV cells. PMID:23482290

Cho, Changsoon; Lee, Jung-Yong

2013-03-11

116

The Potential of Using Solar Energy to Process Full-Fat Soybeans (Glycine max) to Reduce Urease Activity  

Microsoft Academic Search

The objective of this study was to investigate the efficacy of panel solar cookers in reducing urease activity in full-fat soybeans (Glycine max). Changes in urease activity of soaked (SM), coarse-milled (CM) and whole dry (WM) full fat soybeans were investigated by roasting for 0, 30, 60, 90, 120, 150 and 180 min in multiple reflector panel solar cookers, in

O. Nyoni; I. Mpofu; S. Makuza

2005-01-01

117

Dynamic coupling in Cooker's sloshing experiment with baffles  

NASA Astrophysics Data System (ADS)

This paper investigates the dynamic coupling between fluid sloshing and the motion of the vessel containing the fluid, for the case when the vessel is partitioned using non-porous baffles. The vessel is modelled using Cooker's sloshing configuration [M. J. Cooker, "Water waves in a suspended container," Wave Motion 20, 385-395 (1994)]. Cooker's configuration is extended to include n - 1 non-porous baffles which divide the vessel into n separate fluid compartments each with a characteristic length scale. The problem is analysed for arbitrary fill depth in each compartment, and it is found that a multitude of resonance situations can occur in the system, from 1 : 1 resonances to (n + 1)-fold 1 : 1: ⋯ : 1 resonances, as well as ?: m: ⋯ : n for natural numbers ?, m, n, depending upon the system parameter values. The conventional wisdom is that the principle role of baffles is to damp the fluid motion. Our results show that in fact without special consideration, the baffles can lead to enhancement of the fluid motion through resonance.

Turner, M. R.; Bridges, T. J.; Ardakani, H. Alemi

2013-11-01

118

Progress in the utilization of solar energy in Chile  

Microsoft Academic Search

Solar energy research in Chile is discussed in terms of indirect and direct utilization. Solar evaporation, solar distillation, and solar heating are examples of indirect utilization. Specific projects involving the production of table salt from sea water are explained, and equipment used for solar desalination, cookers, and furnaces is described. Research on the direct utilization of solar energy includes studies

J. G. Hirschmann; B. Seifert

1977-01-01

119

Student Parabolic Flight Campaign  

NASA Astrophysics Data System (ADS)

After the successful Student Parabolic Flight Campaigns held in 1994 and 1995, the European Space Agency resumed their organisation of parabolic flight campaigns, dedicated to students of all ESA member states on an annual basis. The Student Parabolic Flight Campaigns are in order to promote microgravity research among students, tomorrow's scientists, since students can bring new ideas and initiatives to the space industry. Already four parabolic flight campaigns have flown and the 2002 student parabolic flight campaign has just flown in September. Thirty experiments are selected to fly in each campaign using the criteria of originality, demonstration of zero G, technical complexity and outreach performed by the team. Each experiment team consists of four university students. This is the chance for students to have the real weightlessness experience on board of the A300 ZERO-G aircraft. In addition, for one or two of the very best student experiments from each campaign, there will be the possibility to re-fly themselves and their experiment on ESA's Professional Parabolic Flight Campaigns. Eventually, one student experiment will be flying to the International Space Station. Conclusively, students' experiments can get fundamentally new and exciting results!

Sentse, N. S. M.; Ockels, W. J.

2002-01-01

120

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.

121

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

122

New prospects in solar cooking  

SciTech Connect

Two studies have been completed recently for Gesellschaft fur Technische Zusammenarbeit and German Appropriate Technology Exchange. The first of these studies contains the following: a classification scheme for solar cookers according to collector type, heat transfer mechanism, and type of use; an assessment of the potential interest of different cooker concepts; a catalogue of 160 different solar cookers that have been tested and/or used in the field. The second study highlights the potential advantages of multi-energy (solar plus back-up) cooking and analyzes its particular boundary conditions. A choice of possible concepts for use in institutions is presented. Particular attention is paid to the problem of efficient heat transfer into removable cooking vessels. Social and cultural factors concerning the acceptance of new technologies are also discussed.

Grupp, M. [Synopsis Inst., Lodeve (France); Klingshirn, A. [GATE, Eschborn (Germany)

1992-12-31

123

Experimental parabolic trough collector performance characterization  

NASA Astrophysics Data System (ADS)

Experimental data from the Collector Module Test Facility at Sandia National Laboratories, Albuquerque, are used to develop a collector performance model and characterize three parabolic trough solar collectors. The independent variables used in the model are selected and fitted to the experimental data using a multiple linear regression technique. The collector model developed accounts for optical performance, including incident angle effects and thermal losses, both linear and nonlinear.

Lukens, L. L.

1981-05-01

124

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

125

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

126

Distributed neural signals on parabolic cylindrical shells  

NASA Astrophysics Data System (ADS)

Parabolic cylindrical shells are commonly used as key components in communication antennas, space telescopes, solar collectors, etc. This study focuses on distributed modal neural sensing signals on a flexible simply-supported parabolic cylindrical shell panel. The parabolic cylindrical shell is fully laminated with a piezoelectric layer on its outer surface and the piezoelectric layer is segmented into infinitesimal elements (neurons) to investigate the microscopic distributed neural sensing signals. Since the dominant vibration component of the shell is usually the transverse oscillation, a new transverse mode shape function is defined. Two shell cases, i.e., the ratio of the meridian height to the half span distance of a parabola at 1:4 (shallow) and 1:1 (deep), are studied to reveal the curvature effect to the neural sensing signals. Studies suggest that the membrane signal component dominates for lower natural modes and the bending signal component dominates for higher natural modes. The meridional membrane and bending signal components are mostly concentrated on the high-curvature areas, while the longitudinal bending component is mostly concentrated on the relatively flat areas. The concentration behavior becomes more prominent as the parabolic cylindrical shell deepens, primarily resulting from the enhanced membrane effect due to the increased curvature.

Hu, S. D.; Li, H.; Tzou, H. S.

2013-06-01

127

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

128

Session: Parabolic Troughs (Presentation)  

SciTech Connect

The project description is R and D activities at NREL and Sandia aimed at lowering the delivered energy cost of parabolic trough collector systems and FOA awards to support industry in trought development. The primary objectives are: (1) support development of near-term parabolic trought technology for central station power generation; (2) support development of next-generation trought fields; and (3) support expansion of US trough industry. The major FY08 activities were: (1) improving reflector optics; (2) reducing receiver heat loss (including improved receiver coating and mitigating hydrogen accumulation); (3) measuring collector optical efficiency; (4) optimizing plant performance and reducing cost; (5) reducing plant water consumption; and (6) directly supporting industry needs, including FOA support.

Kutscher, C.

2008-04-01

129

Parabolic nondiffracting optical wave fields.  

PubMed

We demonstrate the existence of parabolic beams that constitute the last member of the family of fundamental nondiffracting wave fields and determine their associated angular spectrum. Their transverse structure is described by parabolic cylinder functions, and contrary to Bessel or Mathieu beams their eigenvalue spectrum is continuous. Any nondiffracting beam can be constructed as a superposition of parabolic beams, since they form a complete orthogonal set of solutions of the Helmholtz equation. A novel class of traveling parabolic waves is also introduced for the first time. PMID:14719655

Bandres, Miguel A; Gutirrez-Vega, Julio C; Chvez-Cerda, Sabino

2004-01-01

130

Advances in solar technology  

SciTech Connect

This three volume set gives a comprehensive review of the accomplishments in solar energy utilization up to the year 1986. Each chapter is fully annotated with references. The general arrangement is that Volume 1 give the fundamentals of solar heat collection and storage while the other volumes give the details of specific applications. Volume 2 uses this information in discussing the solar heating of buildings, heat energy for industry, solar refrigeration and solar-thermal power generation. Volume 3 takes up a variety of applications, including solar cookers, desalination devices, food drying, greenhouses and photovoltaics.

Garg, H.P.

1987-01-01

131

A Slice of Solar Cooking.  

ERIC Educational Resources Information Center

Presents an inquiry activity in which students design a solar cooking apparatus. Students are also asked to write a paragraph that explains the ways in which science knowledge helped them in the design of their cooker. Includes a grading rubric. (SOE)

Galus, Pamela

2003-01-01

132

Nonimaging secondary concentrators for large rim angle parabolic troughs with tubular absorbers  

NASA Astrophysics Data System (ADS)

For parabolic trough solar collectors with tubular absorbers, we design new tailored secondary concentrators. The design is applicable for any rim angle of a parabolic reflector. With the secondary, the concentration can be increased by a factor of more than 2 with a compact secondary reflector consisting of a single piece, even for the important case of a rim angle of 90 deg. The parabolic reflector can be used without changes; the reduced absorber is still tubular but smaller than the original absorber and slightly displaced toward the primary. concentrators, solar trough collectors, tailored reflectors.

Ries, Harald; Spirkl, Wolfgang

1996-05-01

133

The Pressure Cooker: A Module on the Properties of Matter. Tech Physics Series.  

ERIC Educational Resources Information Center

Experiments to provide an understanding of the principles related to the pressure cooker are presented. Objectives included are designed to provide the learner with the ability to calibrate a thermistor for measuring temperature; explain the meaning of latent and specific heat; calculate latent and specific heat; use a Bourdon tube pressure gauge

Technical Education Research Center, Cambridge, MA.

134

Progress in solar thermal distributed receiver technology  

NASA Astrophysics Data System (ADS)

A brief discussion is given on the fundamentals of parabolic dish collectors. Private and Department of Energy supported projects which employ parabolic dish collector systems are described. These projects include: the Distribution Receiver Test Facility, Shenandoah Solar Total Energy Project, Vangurd I, Solar Plant No. 1, the Dish/Stirling Solar Electric Generating System, the Organic Rankine Cycle, and the Solarized Automotive Gas Turbine.

Leonard, J. A.; Otts, J. V.

135

Solar thermal technology evaluation, fiscal year 1982. Volume 1: Executive summary  

NASA Astrophysics Data System (ADS)

Three primary solar concepts the central receiver, parabolic dish, and parabolic trough are investigated. To a lesser extent, the hemispherical bowl and salt-gradient solar pond are also being studied. Each technology is described.

1983-07-01

136

Solar thermal technology evaluation, fiscal year 1982. Volume 1: Executive summary  

NASA Technical Reports Server (NTRS)

Three primary solar concepts the central receiver, parabolic dish, and parabolic trough are investigated. To a lesser extent, the hemispherical bowl and salt-gradient solar pond are also being studied. Each technology is described.

1983-01-01

137

Complex Ruelle Operator in a Parabolic Basin  

E-print Network

Complex Ruelle Operator in a Parabolic Basin Dynamical Systems _ where it is and where it is going". 1. Parabolic basin and holomorphic quadratic- __ __ ciated to a parabolic basin of a complex dynamical system. Let R : |C! |C be a rational mapping

Ushiki, Shigehiro

138

A parabolic Pommerenke-Levin-Yoccoz inequality.  

E-print Network

A parabolic Pommerenke-Levin-Yoccoz inequality. Xavier Buff Universit´e Paul Sabatier Laboratoire45. Key words. Holomorphic Dynamics. Parabolic. Holomorphic Index. Pommerenke- Levin-hyperbolic dynamics (PRODYN) Research partially supported under NSF grant DMS 9803242 1 #12;A parabolic Pommerenke-Levin

Epstein, Adam

139

Solar thermal parabolic dish energy applications  

NASA Technical Reports Server (NTRS)

Vu-graphs are presented that show that applications are a viable distributed renewable power generation option. Quality energy can be produced in the form of electricity and high temperature heat. Modular systems are described that can be distributed to new or existing plants and that are mass producible with the associated economies of production.

Pijawka, W.

1981-01-01

140

Concentrating Solar Power Commercial Application Study  

E-print Network

Concentrating Solar Power Commercial Application Study: Reducing Water Consumption of Concentrating Solar Power Electricity Generation Report to Congress U.S. Department of Energy This report is being Concentrating Solar Power Technologies............................................... 7 Parabolic Troughs

Laughlin, Robert B.

141

INCREASING EFFICIENCY OF SOLAR COOK- ER BY USING CO2 GAS  

E-print Network

ABSTRACT- A local survey was made to find whether people are not using solar cooker because it is time consuming even after receiving enough sunlight. To decrease the time of cooking of solar cooker temperature of cooking box should be increased for that a greenhouse gas- CO2 is used. The easiest and economical way of producing CO2- adding lemon juice to baking soda was used. To verify this fact a comparative study was done which concluded that the temperature can be increased. Also the expenditure for this was calculated which shows that use of this technique will be economical than using conventional way. KEY WORDS:- solar cooker, temperature rising factor, greenhouse gas, CO2, lemon juice, baking soda, less expenditure. 1

Gauree K. Wathodkar; P. T. Agrawal

142

Energy 101: Concentrating Solar Power  

NSDL National Science Digital Library

This video describes how concentrating solar power (CSP) technologies reflect and collect solar energy to generate electricity. This video explains what CSP is, how it works, and focuses on parabolic troughs.

National Renewable Energy Laboratory (NREL)

143

Parabolic Trouogh Optical Characterization at the National Renewable Energy Laboratory  

SciTech Connect

Solar parabolic trough power plant projects are soon to be implemented in the United States and internationally. In addition to these new projects, parabolic trough power plants totaling approximately 350 MW already exist within the United States and have operated for close to 20 years. As such, the status of the technology exists within several different phases. Theses phases include R&D, manufacturing and installation, and operations and maintenance. One aspect of successful deployment of this technology is achieving and maintaining optical performance. Different optical tools are needed to assist in improving initial designs, provide quality control during manufacture and assembly, and help maintain performance during operation. This paper discusses several such tools developed at SunLab (a joint project of the National Renewable Laboratory and Sandia National Laboratories) for these purposes. Preliminary testing results are presented. Finally, plans for further tool development are discussed.

Wendelin, T. J.

2005-01-01

144

Nonlinear elliptic-parabolic problems  

E-print Network

We introduce a notion of viscosity solutions for a general class of elliptic-parabolic phase transition problems. These include the Richards equation, which is a classical model in filtration theory. Existence and uniqueness results are proved via the comparison principle. In particular, we show existence and stability properties of maximal and minimal viscosity solutions for a general class of initial data. These results are new even in the linear case, where we also show that viscosity solutions coincide with the regular weak solutions introduced in [Alt&Luckhaus 1983].

Kim, Inwon C

2012-01-01

145

Heat and Chemical Exergy Analysis of Parabolic Trough Collector  

NASA Astrophysics Data System (ADS)

Emissions of greenhouse gases and other pollutants, derived from the combustion of fossil fuels for heat and electricity generation, can be significantly reduced or even completely eliminated by substituting fossil fuels with a clean energy source, e.g. solar energy. However, solar radiation reaching the earth is diluted, intermittent, and, unequally distributed. These disadvantages can be overcome by converting solar energy into chemical energy carriers, i.e. solar fuels, such as solar hydrogen and solar methanol, which can be long-termed stored and long-ranged transported. Since the energy conversion efficiency of thermochemical processes is limited by the Carnot efficiency, the use of concentrated solar radiation as the source of high-temperature process heat provides a thermodynamically efficient path for the conversion of solar energy into chemical fuels. In this study, water-gas shift reaction in parabolic trough collector is evaluated with regarding the heat exergy and chemical exergy analyses and the results are given as tables and graphs.

ztrk, M.; gl, I.; zek, N.

2007-04-01

146

Individual homogenization of nonlinear parabolic Y. Efendiev  

E-print Network

Individual homogenization of nonlinear parabolic operators Y. Efendiev and L. Jiang A. Pankov October 9, 2006 Abstract In this paper, we prove an individual homogenization result for a class of almost parabolic operators. Further, using these estimates, the individual homogenization result is shown. AMS

Efendiev, Yalchin

147

Liquid surface waves in parabolic tanks  

Microsoft Academic Search

Surface waves in cylindrical tanks with parabolic cross section formed by two confocal parabolas are studied. Exact general solutions for the inviscid gravity-capillary waves as function of the parabolic curvatures are presented, and the symmetry of the eigensolutions for the velocity potential modes is also investigated. For a complete characterization of the velocity potential and of the amplitude of the

C. Trallero-Giner; A. Buchleitner

2008-01-01

148

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

149

Simulation of point light concentration with parabolic trough collector  

NASA Astrophysics Data System (ADS)

As the amount of solar generated energy usage increases worldwide, researches are turning to more advanced methods to increase collection efficiencies and drive down system costs. In this paper, four different optical system designs for solar concentrator applications are discussed. Each of the designs studied utilizes a parabolic trough optical element. The use of the parabolic trough in conjunction with a secondary optical component eliminates the need for expensive complicated 2-axis tracking, whilst still allowing the precise point focus normally only possible with more complex paraboloid systems. The result is an optical system, which offers all the advantages of a linear focus geometry combined with the possibility to utilize point focus concentration. The results were obtained using photometric geometrical ray tracing methods. Ideal surface simulations were initially used to separate surface from geometrical loss contributions. Later, more realistic simulations, including surface and reflectivity data of typical manufacturing methods and materials, were used to compare optical output power densities and system losses. For the systems studied, the minimum and maximum optical efficiencies obtained were 76.73% and 81% respectively. The AM 1.5 solar spectrum power densities in the absorption plane ranged from 50 to 195.8Wm-2.

Danylyuk, Andriy; Zettl, Marcus; Lynass, Mark

2010-08-01

150

Pre- and post-natal exposure of children to EMF generated by domestic induction cookers  

NASA Astrophysics Data System (ADS)

Induction cookers are a type of cooking appliance that uses an intermediate-frequency magnetic field to heat the cooking vessel. The magnetic flux density produced by an induction cooker during operation was measured according to the EN 62233 standard, and the measured values were below the limits set in the standard. The measurements were used to validate a numerical model consisting of three vertically displaced coaxial current loops at 35 kHz. The numerical model was then used to compute the electric field (E) and induced current (J) in 26 and 30 weeks pregnant women and 6 and 11 year old children. Both E and J were found to be below the basic restrictions of the 2010 low-frequency and 1998 ICNRIP guidelines. The maximum computed E fields in the whole body were 0.11 and 0.66 V m-1 in the 26 and 30 weeks pregnant women and 0.28 and 2.28 V m-1 in the 6 and 11 year old children (ICNIRP basic restriction 4.25 V m-1). The maximum computed J fields in the whole body were 46 and 42 mA m-2 in the 26 and 30 weeks pregnant women and 27 and 16 mA m-2 in the 6 and 11 year old children (ICNIRP basic restriction 70 mA m-2).

Kos, Bor; Vali?, Bla; Miklav?i?, Damijan; Kotnik, Tadej; Gajek, Peter

2011-10-01

151

Development of a Molten-Salt Thermocline Thermal Storage System for Parabolic Trough Plants  

Microsoft Academic Search

Thermal storage improves the dispatchability and marketability of parabolic trough power plants allowing them to produce electricity on demand independent of solar collection. One such thermal storage system, a thermocline, uses a single tank containing a fluid with a thermal gradient running vertically through the tank, where hotter fluid (lower density) is at the top of the tank and colder

James E. Pacheco; Steven K. Showalter; William J. Kolb

2002-01-01

152

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

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

PARABOLIC OBSTACLE PROBLEMS APPLIED TO FINANCE A ...  

E-print Network

supper-solution (for a given parabolic operator, and given domain and ... of the American put option of minimum of two underliers, see last section. 1.2. ...... Mark Broadie and Jrme Detemple, The valuation of American options on multiple.

2006-03-07

155

High order difference methods for parabolic equations  

E-print Network

HIGH ORDER DIFFERENCE METHODS FOR PARABOLIC E(PATIONS A Thesis by Daniel Alan Matuska Submitted to the Graduate College of Texas A&M University in partial fulfillment of the requirement for the degree of MASTER OF SCIENCE May 1971 Ma...)or Sub]ect: Mathematics HIGH ORDER DIFFERENCE METHODS FOR PARABOLIC EQUATIONS A Thesis by Daniel Alan Matuska Approved as to style and content by: Pc~ &~ (Chairman of Committee) (Head of Department) (Member) C . (Member) (Member) (Member...

Matuska, Daniel Alan

2012-06-07

156

Mode-locked parabolic Raman fiber oscillator  

Microsoft Academic Search

The generation of self-similar parabolic pulses (similaritons) has so far only been obtained in single-pass Raman amplifier configurations or in rare-earth doped fiber lasers. We report here the first demonstration of a mode-locked parabolic pulse fiber laser, which can potentially be run at any wavelength using Raman gain. This new all-fiber ring similariton laser scheme has been designed with the

C. Aguergaray; V. I. Kruglov; D. Mechin; J. D. Harvey

2009-01-01

157

75 FR 41231 - Notice of Intent To Prepare an Environmental Impact Statement for the Proposed Abengoa Solar Inc...  

Federal Register 2010, 2011, 2012, 2013

...operation, maintenance, and termination of a solar energy generation project. The proposed Lathrop Wells Solar Facility project would consist of a concentrated solar power facility including a solar parabolic...

2010-07-15

158

A Process Heat Application Using Parabolic Trough Collector  

NASA Astrophysics Data System (ADS)

A pilot study has been performed based on a heat process application that is designed, installed and tested at Gaziantep University to establish the technical and economic feasibility of high temperature solar-assisted cooking process. The system has been designed to be satisfying the process conditions integrated with parabolic trough solar collector (PTSC). It is primarily consists of the PTSC array, auxiliary heater, plate type heat exchanger, cooking system and water heating tanks. In the operation of the process heat application, the energy required to cook wheat (used as cooking material) has been supplied from solar energy which is transferred to heat transfer fluid (HTF) by heat exchanging units and finally discharged to water in order to produce bulgur. The performance parameters of the sub-systems and the process compatibility have been accomplished depending on the system operation. In addition that the system performance of the high temperature solar heat process has been presented and the recommendations on its improvement have been evaluated by performing an experimental study. As a result that the use of solar energy in process heat application has been projected and its contribution to economics view with respect to conventional cooking systems has been conducted.

Y?lmaz, ?brahim Halil; Sylemez, Mehmet Sait; Hayta, Hakan; Yumruta?, Recep

159

Solar thermal technology  

NASA Astrophysics Data System (ADS)

This annual evaluation report provides the accomplishments and progress of government-funded activities initiated, renewed, or completed during Fiscal Year 1985 (October 1, 1984 through September 30, 1985). It highlights the program tasks conducted by participating national laboratories and by contracting industrial academic, or other research institutions. The focus of the STT Program is research and development leading to the commercial readiness of four primary solar thermal concepts: (1) central receiver; (2) parabolic dish; (3) parabolic trough; and (4) hemispherical bowl.

1986-08-01

160

Piecewise-Planar Parabolic Reflectarray Antenna  

NASA Technical Reports Server (NTRS)

The figure shows a dual-beam, dualpolarization Ku-band antenna, the reflector of which comprises an assembly of small reflectarrays arranged in a piecewise- planar approximation of a parabolic reflector surface. The specific antenna design is intended to satisfy requirements for a wide-swath spaceborne radar altimeter, but the general principle of piecewise-planar reflectarray approximation of a parabolic reflector also offers advantages for other applications in which there are requirements for wideswath antennas that can be stowed compactly and that perform equally in both horizontal and vertical polarizations. The main advantages of using flat (e.g., reflectarray) antenna surfaces instead of paraboloidal or parabolic surfaces is that the flat ones can be fabricated at lower cost and can be stowed and deployed more easily. Heretofore, reflectarray antennas have typically been designed to reside on single planar surfaces and to emulate the focusing properties of, variously, paraboloidal (dish) or parabolic antennas. In the present case, one approximates the nominal parabolic shape by concatenating several flat pieces, while still exploiting the principles of the planar reflectarray for each piece. Prior to the conception of the present design, the use of a single large reflectarray was considered, but then abandoned when it was found that the directional and gain properties of the antenna would be noticeably different for the horizontal and vertical polarizations.

Hodges, Richard; Zawadzki, Mark

2009-01-01

161

Effects of infrared radiation, solar cooking and microwave cooking on alpha-amylase inhibitor in sorghum (Sorghum bicolor L.).  

PubMed

Three domestic cooking methods were studied in alpha-amylase inhibitory activity in sorghum grains. In all the treatments, overnight soaked seeds lost amylase inhibitory activity much faster. All the three treatments reduced the inhibitory activity. Use of solar cooker for reducing amylase inhibitory activity works out very economically and efficiently. Microwave cooking eliminates amylase inhibitory activity within 5 minutes. PMID:7855094

Mulimani, V H; Supriya, D

1994-10-01

162

Liquid surface waves in parabolic tanks  

NASA Astrophysics Data System (ADS)

Surface waves in cylindrical tanks with parabolic cross section formed by two confocal parabolas are studied. Exact general solutions for the inviscid gravity-capillary waves as function of the parabolic curvatures are presented, and the symmetry of the eigensolutions for the velocity potential modes is also investigated. For a complete characterization of the velocity potential and of the amplitude of the liquid surface, their analytic expressions in terms of hypergeometric functions are given. It is shown that for the particular case of two confocal parabolas with the same curvature, the velocity potential is described by the cylindrical functions. The evolution of the nodal structure for gravity-capillary waves for variable excitation, and in terms of the parabolic tank curvature, is analyzed.

Nez-Fernndez, Y.; Trallero-Giner, C.; Buchleitner, A.

2008-11-01

163

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

164

Finite Difference Method for Stochastic Parabolic Equations  

NASA Astrophysics Data System (ADS)

In the present paper the single step difference schemes for the multi-point non local-boundary value problems for the stochastic parabolic equation are presented. The convergence estimates for the solution of these difference schemes are established. In applications this abstract result permit us to obtain the convergence estimates for the solution of difference schemes for the numerical solution of multi-point non-local boundary value problems for parabolic equations. The theoretical statements for the solution of this difference schemes are supported by the results of numerical experiments.

Ashyralyev, Allaberen; San, Mehmet Emin

2011-09-01

165

Development status of the PDC-1 Parabolic Dish Concentrator  

NASA Technical Reports Server (NTRS)

The status of development of the 12 m diameter parabolic dish concentrator which is planned for use with the Small Community Solar Thermal Power System. The PDC-1 unit features the use of plastic reflector film bonded to structural plastic gores supported by front-bracing steel ribs. An elevation-over-azimuth mount arrangement is employed, with a conventional wheel-and-track arrangement; outboard trunnions permit the dish to be stored in the face down position, with the added advantage of easy access to the power conversion assembly. The control system is comprised of a central computer (LSI 1123), a manual control panel, a concentrator control unit, two motor controllers, a Sun sensor, and two angular position resolvers. The system is designed for the simultaneous control of several concentrators. The optical testing of reflective panels is described.

Thostesen, T.; Soczak, I. F.; Pons, R. L.

1982-01-01

166

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

167

PARABOLIC BOUNDARY HARNACK PRINCIPLES IN DOMAINS ...  

E-print Network

This kind of sets appear naturally in free boundary problems governed by par- ... In particular, we show that this argument indeed can be successfully carried out in .... we say that a sequence of parabolic cylinders Qri (xi,ti) ? D, i = 1,...,N is a.

2013-12-31

168

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

169

Status of the current parabolic dish technology  

NASA Technical Reports Server (NTRS)

Vu-graphs are presented that show that point focus distributed receiver distributed generation systems are cost competitive with current utilities. System cost caveats and typical power module costs are described. Major problems inhibiting commercialization of the parabolic dish technology were reviewed.

Sumrall, C.

1981-01-01

170

Influence of errors of trough pointing and fin alignment on the geometrical concentration ratio of focusing parabolic concentrators  

NASA Astrophysics Data System (ADS)

Geometrical behavior of a focusing parabolic trough with a fin receiver has been studied in detail keeping in view the interesting application of this system for photovoltaic conversion of solar energy through double-sided and multiple-junction edge illuminated solar cells. Results regarding the influence of the pointing errors of the trough and alignment errors of the fin on the geometrical concentration ratio of the system are presented.

Mathur, S. S.; Kandpal, T. C.; Singh, R. N.; Singhal, A. K.

1981-09-01

171

76 FR 28064 - Notice of Availability of the Final Environmental Impact Statement for Palen Solar I, LLC's Palen...  

Federal Register 2010, 2011, 2012, 2013

...rows of parabolic mirrors focusing solar energy on collector tubes. The tubes...the project area as suitable for solar energy production. In addition to the...project area as available to future solar energy power generation projects;...

2011-05-13

172

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

173

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

174

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

175

Parabolic subgroups and Einstein solvmanifolds 1 . Einstein ,  

E-print Network

, M = G/K , G M() . P G , P M() . , (parabolic subalgebra) . G ( , ). 2.2 g g = kZ gk gradation ( Z-gadation) , [gk, gl] gk+l (k, l Z) . 2 #12;, . , gradation . , , gradation . 2.3 p g , g gradation g = gk p = k0 gk . . , , . p g , [] M() ( M() , ). o M = G/K , g = k + m o Cartan . : [0, +) M , (t) = exp

Tamaru, Hiroshi

176

Beryllium parabolic refractive x-ray lenses  

Microsoft Academic Search

Parabolic refractive x-ray lenses are novel optical components for the hard x-ray range from about 5 keV to about 120 keV. They focus in both directions. They are compact, robust, and easy to align and to operate. They can be used like glass lenses are used for visible light, the main difference being that the numerical aperture N.A. is much

Christian G. Schroer; Marion Kuhlmann; Til F. Gnzler; Olga Kurapova; Federico Zontone; Alexandre S. Simionovici; Anatoly A. Snigirev; Irina Snigireva

2004-01-01

177

Systematic rotation and receiver location error effects on parabolic trough annual performance  

NASA Astrophysics Data System (ADS)

The effects of systematic geometrical design errors and random optical errors on the accuracy and subsequent economic viability of solar parabolic trough concentrating collectors were studied to enable designers to choose and specify necessary design and material constraints. A three-dimensional numerical model of a parabolic trough was analyzed with the inclusion of errors of pointing and mechanical deformation, and data from a typical meteorological year. System errors determined as percentage standard deviations provided the range of a study for systematic rotation and receiver location errors. The two types of errors were found to produce compounded effects. It is concluded that the designer must choose performance levels which take into account existence of errors, must know to what level the errors can be eliminated and at what cost, and should make provisions for monitoring the day-to-day on-line focus of the troughs.

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

1981-11-01

178

Analysis of static and quasi-static cross compound parabolic concentrators  

SciTech Connect

Static and quasi-static concentrators present interesting characteristics for obtaining photovoltaic solar energy. In this work we study the characteristics of the crossed compound parabolic concentrator, formed by the intersection of two cyclindrical compound parabolic concentrators (CPC). Bifacial cells are used in this concentrator as a requirement for obtaining higher concentrations. Static and quasi-static concentrators see the sun as an extended source, so a simplified source model of radiance for the sky of Madrid is used. The figures of merit of a lossless concentrator are studied and the most important parameters influencing its optical behavior are discussed. We conclude that these concentrators obtain results that lead to a decrease in the cost of photovoltaic energy.

Molledo, A.G.; Luque, A.

1984-06-15

179

Cogenerating Photovoltaic and Thermal Solar Collector  

E-print Network

Cogenerating Photovoltaic and Thermal Solar Collector Jinny Rhee and Jim Mokri COE Faculty · Solar Energy and Alternative Energy can contribute to the energy supply ­ Renewable, doesn't emit peak load and irradiance hours of the day #12;Design · Parabolic solar collector · GaAs PV cells

Su, Xiao

180

Determinant line bundle on moduli space of parabolic bundles  

Microsoft Academic Search

In Biswas and Raghavendra (Proc Indian Acad Sci (Math Sci) 103:4171, 1993; Asian J Math 2:303324, 1998), a parabolic determinant line bundle on a moduli space of stable parabolic bundles was constructed, along with a Hermitian\\u000a structure on it. The construction of the Hermitian structure was indirect: The parabolic determinant line bundle was identified\\u000a with the pullback of the determinant

Indranil Biswas

2011-01-01

181

On the invariants of two dimensional linear parabolic equations  

NASA Astrophysics Data System (ADS)

We consider the most general two dimensional linear parabolic equations. Motivated by the recent work of Ibragimov et al. [1-3] we construct differential invariants, semi-invariants and invariant equations. These results are achieved with the employment of the equivalence group admitted by this class of parabolic equations. We derive those variable coefficient equations of this class of linear parabolic equations that can be mapped into constant coefficient equations. Further applications are presented.

Tsaousi, C.; Sophocleous, C.; Tracin, R.

2012-09-01

182

Engineering aspects of a molten salt heat transfer fluid in a trough solar field  

Microsoft Academic Search

An evaluation was carried out to investigate the feasibility of utilizing a molten salt as the heat transfer fluid (HTF) and for thermal storage in a parabolic trough solar field to improve system performance and to reduce the levelized electricity cost. The operating large-scale solar parabolic trough plants in the USA currently use a high temperature synthetic oil in the

D. Kearney; B. Kelly; U. Herrmann; R. Cable; J. Pacheco; R. Mahoney; H. Price; D. Blake; P. Nava; N. Potrovitza

2004-01-01

183

Frequency independent parabolic phased antenna array of log periodic antennas  

NASA Astrophysics Data System (ADS)

A frequency-independent phased array antenna made of log-periodic radiators is presented which, in contrast to the Duhamel array, does not employ phase shifters at the antenna inputs to produce radiation in the main direction. The array considered here is a system of radial log-periodic radiators that form a parabolic phased-array antenna. The dipoles of all the radiators having the same size are located along a parabolic line. The operation of the parabolic array at various frequencies is equivalent to that of a series of confocal parabolic mirror antennas excited from a single source.

Veriga, B. A.; Vyakhirev, N. I.

1984-03-01

184

Parabolic Trough VSHOT Optical Characterization in 2005-2006 (Presentation)  

SciTech Connect

This presentation regarding parabolic trough VSHOT optical characterization describes trough deployment and operation phases including: development, manufacture/installation, and maintenance/operation.

Wendelin, T.

2006-02-01

185

THE PARABOLIC-PARABOLIC KELLER-SEGEL MODEL IN R2 VINCENT CALVEZ AND LUCILLA CORRIAS  

E-print Network

-parabolic Keller-Segel in the full space. We derive a critical mass threshold below which global existence of embryonic development for instance. Among mathematical models describing spatial organization of biological, a (PKS) type model has been suggested to solve a remarkable pattern formation issue in the human brain

Calvez, Vincent

186

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

187

Numerical Schemes for Rough Parabolic Equations  

SciTech Connect

This paper is devoted to the study of numerical approximation schemes for a class of parabolic equations on (0,1) perturbed by a non-linear rough signal. It is the continuation of Deya (Electron. J. Probab. 16:1489-1518, 2011) and Deya et al. (Probab. Theory Relat. Fields, to appear), where the existence and uniqueness of a solution has been established. The approach combines rough paths methods with standard considerations on discretizing stochastic PDEs. The results apply to a geometric 2-rough path, which covers the case of the multidimensional fractional Brownian motion with Hurst index H>1/3.

Deya, Aurelien, E-mail: deya@iecn.u-nancy.fr [Universite de Nancy 1, Institut Elie Cartan Nancy (France)

2012-04-15

188

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

189

Solar thermal technology  

NASA Astrophysics Data System (ADS)

The accomplishments and progress of the US Department of energy solar thermal technology (STT) program during FY 1983 are documented. The focus of the STT program is research and development leading to the commercial readiness of three primary solar thermal concepts: the central receiver, parabolic dish, and parabolic trough. The hemispherical bowl and salt-gradient solar pond are also being studied. This development effort is complemented by numerous research and planning activities. A brief description of each technology and highlights of the fiscal year's technical activities is given. FY 1983 accomplishments are enumerated and a bibliography, list of contacts, acronyms, and definitions of terms relevant to solar thermal technology and the STT program are included.

1984-08-01

190

Solar Disinfection of MODS Mycobacterial Cultures in Resource-Poor Settings  

PubMed Central

Introduction Safe disposal of TB culture material in which the infectious burden of clinical samples has been greatly amplified is an important challenge in resource-limited settings. The bactericidal capacity of solar cookers has been demonstrated previously for conventional bacteria and contaminated clinical waste. We investigated the use of a simple solar cooker for the sterilization of mycobacterial broth cultures from the microscopic observation drug susceptibility assay (MODS). Methods Simulated TB culture materials were prepared by inoculating 24-well MODS plates with 500 L of a known concentration of Mycobacterium bovis BCG. In a series of experiments, samples were simultaneously placed inside a box-type solar cooker and control box and removed at timepoints between 15 minutes and 6 hours. Quantitative cultures were performed using retrieved samples to determine sterilization effect. Results All cultures from the control box were positive at or within 14 logs of inoculation concentration. Simulated culture plates at concentrations from 103colony-forming-units (CFU)/ml to 107 CFU/ml were completely sterilized after only one hour of cooker exposure, at temperatures between 50102C. At 109 CFU/ml (far in excess of diagnostic cultures), it was only possible to recover mycobacterial growth in plates removed after 15 minutes. By 30 minutes all plates were effectively sterilized. Discussion Solar disinfection provides a very effective, safe and low-cost alternative to conventional equipment used for disposal of mycobacterial culture material. Effect of climatic conditions and optimal operating procedure remain to be defined. PMID:17971863

Nathavitharana, Ruvandhi; Coronel, Jorge; Moore, David A. J.

2007-01-01

191

Development of a combined photovoltaic/thermal linear receiver for a parabolic trough concentrator  

NASA Astrophysics Data System (ADS)

The development of a receiver design for a linear focus concentrator is discussed. The design concept described employs a pair of nested glass tubes. A specially configured inner borosilicate glass tube functions as the mounting surface for the solar cell circuit in this dual focus receiver geometry. This inner tube, which is capped at each end to provide an interior dead air space, is inserted within a 2 inch ID glass pipe which is part of Corning Pyrex beaded pressure process piping system. The selected receiver coolant, which is designated as Synfluid (2 centistokes kineamatic viscosity), is circulated through the outer glass pipe in direct contact with the solar cell circuit active area. The concentrated irradiance from the parabolic trough impinges on the outer glass pipe and is optically transmitted through the clear synthetic mineral oil to the solar cell circuit. Two prototype receivers of this design were fabricated and assembled.

1980-12-01

192

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

193

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

NASA Astrophysics Data System (ADS)

Improved parabolic trough concentrating collectors which result from better design, improved fabrication techniques, and the development and utilization of improved materials are analyzed. 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. It is shown that the performance and economic potential of these improvements are substantial, especially at higher collector operating temperatures.

Gee, R.; Murphy, L. M.

1981-08-01

194

THE PARABOLIC JET STRUCTURE IN M87 AS A MAGNETOHYDRODYNAMIC NOZZLE  

SciTech Connect

The structure and dynamics of the M87 jet from sub-milliarcsec to arcsecond scales are continuously examined. We analyzed the Very Long Baseline Array archival data taken at 43 and 86 GHz to measure the size of very long baseline interferometry (VLBI) cores. Millimeter/sub-millimeter VLBI cores are considered as innermost jet emissions, which has been originally suggested by Blandford and Knigl. Those components fairly follow an extrapolated parabolic streamline in our previous study so that the jet has a single power-law structure with nearly 5 orders of magnitude in the distance starting from the vicinity of the supermassive black hole (SMBH), less than 10 Schwarzschild radius (r{sub s}). We further inspect the jet parabolic structure as a counterpart of the magnetohydrodynamic (MHD) nozzle in order to identify the property of a bulk acceleration. We interpret that the parabolic jet consists of Poynting-flux dominated flows, powered by large-amplitude, nonlinear torsional Alfvn waves. We examine the non-relativistic MHD nozzle equation in a parabolic shape. The nature of trans-fast magnetosonic flow is similar to the one of transonic solution of Parker's hydrodynamic solar wind; the jet becomes super-escape as well as super-fast magnetosonic at around ?10{sup 3} r{sub s}, while the upstream trans-Alfvnic flow speed increases linearly as a function of the distance at ?10{sup 2}-10{sup 3} r{sub s}. We here point out that this is the first evidence to identify these features in astrophysical jets. We propose that the M87 jet is magnetically accelerated, but thermally confined by the stratified interstellar medium inside the sphere of gravitational influence of the SMBH potential, which may be a norm in active galactic nucleus jets.

Nakamura, Masanori; Asada, Keiichi, E-mail: nakamura@asiaa.sinica.edu.tw, E-mail: asada@asiaa.sinica.edu.tw [Institute of Astronomy and Astrophysics, Academia Sinica, P.O. Box 23-141, Taipei 10617, Taiwan (China)

2013-10-01

195

Low-cost and gram-scale synthesis of water-soluble Cu-In-S/ZnS core/shell quantum dots in an electric pressure cooker  

NASA Astrophysics Data System (ADS)

We report an electric pressure cooker for large-scale synthesis of water-soluble Cu-In-S/ZnS core/shell quantum dots. Low-cost thioglycolic acid and sodium citrate were used as the dual stabilizers. ~3 grams of quantum dots with a tunable emission from 545 to 610 nm and quantum yield up to 40% were obtained in a batch.We report an electric pressure cooker for large-scale synthesis of water-soluble Cu-In-S/ZnS core/shell quantum dots. Low-cost thioglycolic acid and sodium citrate were used as the dual stabilizers. ~3 grams of quantum dots with a tunable emission from 545 to 610 nm and quantum yield up to 40% were obtained in a batch. Electronic supplementary information (ESI) available: Experimental details, PL decay curves, PL lifetimes, EDS spectra, chemical composition, cost analysis. See DOI: 10.1039/c3nr05014a

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

2014-01-01

196

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

197

Low-cost and gram-scale synthesis of water-soluble Cu-In-S/ZnS core/shell quantum dots in an electric pressure cooker.  

PubMed

We report an electric pressure cooker for large-scale synthesis of water-soluble Cu-In-S/ZnS core/shell quantum dots. Low-cost thioglycolic acid and sodium citrate were used as the dual stabilizers. ?3 grams of quantum dots with a tunable emission from 545 to 610 nm and quantum yield up to 40% were obtained in a batch. PMID:24337019

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

2014-01-01

198

Midtemperature solar systems test faclity predictions for thermal performance based on test data: Solar Kinetics T-700 solar collector with glass reflector surface  

SciTech Connect

Sandia National Laboratories, Albuquerque (SNLA), is currently conducting a program to predict the performance and measure the characteristics of commercially available solar collectors that have the potential for use in industrial process heat and enhanced oil recovery applications. The thermal performance predictions for the Solar Kinetics solar line-focusing parabolic trough collector for five cities in the US are presented. (WHK)

Harrison, T.D.

1981-03-01

199

Optimized solar powered freeze desalination technology  

SciTech Connect

This paper discusses the logic of integrating desalination technology with solar technology. Further analysis leads to the most desirable combination of different variations of these technologies. An integrated power system is proposed consisting of modular parabolic dish point focus solar energy collection, molten salt thermal energy storage, and a conventional steam turbine. 8 refs.

Mukherjee, S.P.; Nowak, T.J.; Husain, M.; Demler, R.; Engdahl, G.E.

1981-01-01

200

On two parabolic systems: Convergence and blowup  

NASA Astrophysics Data System (ADS)

This dissertation studies two parabolic systems. It consists of two parts. In part one (chapter one), we prove a convergence result, namely, the solution (AK,/ BK) of a system of chemical diffusion-reaction equations (with reaction rate K) converges to the solution (A, B) of a diffusion- instantaneous-reaction equation. To prove our main result, we use some L1 and L2 'energy' estimates and a compactness result due to Aubin (1). As a by-product we also prove that as K approaches infinity, the limit solution exhibits phase separation between A and B. In part two (chapter two), we study the blowup rate for a system of heat equations ut=/Delta u,/ vt=/Delta v in a bounded domain ?times(0,T) coupled in the nonlinear Neumann boundary conditions [/partial u/over/partial n]=vp,/ [/partial v/over/partial n]=uq on ?Omega[ 0,T), where p>0,/ q>0,/ pq>1 and n is the exterior normal vector on ?Omega. Under certain assumptions, we establish exact blowup rate which generalizes the corresponding results of some authors' recent work including Deng (2), Deng-Fila-Levine (3) and Hu-Yin (4). ftn (1) J. P. A scUBIN, Un theoreme de compacite, C. R. Acad. Sci., 256(1963), pp. 5042-5044. (2) K. D scENG, Blow-up rates for parabolic systems, Z. Angew. Math. Phys., 47(1996), No. 1, pp. 132-143. (3) K. D scENG, M. F scILA AND H. A. L scEVINE, On critical exponents for a system of heat equations coupled in the boundary conditions, Acta Math. Univ. Comenian. (N.S.), 36(1994), No. 2, pp. 169-192. (4) B. H scU scAND H. M. Y scIN, The profile near blowup time for solutions of the heat equation with a nonlinear boundary condition, Trans. Amer. Math. Soc., 346(1994), pp. 117-135.

Huang, Yamin

1998-12-01

201

Wigner Function for an Impurity in a Parabolic Quantum Dot  

Microsoft Academic Search

High sensitivity of quantum dots with impurities can be linked with phase space high sensitivity to initial conditions. We present the Wigner function for an impurity in a parabolic quantum dot obtained from a variational wavefunction.

Gary Snyder; Majd Mayassi; Praveen Nittala; Tomas Materdey

2006-01-01

202

All-fiber ring Raman laser generating parabolic pulses  

Microsoft Academic Search

We present theoretical and numerical results for an all-fiber laser using self-similar parabolic pulses ('similaritons') designed to operate using self-similar propagation regimes. The similariton laser features a frequency filter and a Sagnac loop which operate together to generate an integrated all-fiber mode-locked laser. Numerical studies show that this laser generates parabolic pulses with linear chirp in good agreement with analytical

V. I. Kruglov; D. Mechin; J. D. Harvey

2010-01-01

203

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

204

Gain-scheduled control of a solar power plant  

Microsoft Academic Search

The application of gain-scheduled control to a pilot-scale solar power plant is described. A field of parabolic collectors focus the solar radiation onto a tube where oil is pumped through in order to collect the solar power. The control problem is to keep the temperature of the oil leaving the field at its desired value by manipulating the oil pump

Tor A. Johansen; Kenneth J. Hunt; Idar Petersen

2000-01-01

205

Parabolic Trough Receiver Heat Loss Testing (Poster)  

SciTech Connect

Parabolic trough receivers, or heat collection elements (HCEs), absorb sunlight focused by the mirrors and transfer that thermal energy to a fluid flowing within them. Thje absorbing tube of these receivers typically operates around 400 C (752 F). HCE manufacturers prevent thermal loss from the absorbing tube to the environment by using sputtered selective Cermet coatings on the absorber and by surrounding the absorber with a glass-enclosed evacuated annulus. This work quantifies the heat loss of the Solel UVAC2 and Schott PTR70 HCEs. At 400 C, the HCEs perform similarly, losing about 400 W/m of HCE length. To put this in perspective, the incident beam radiation on a 5 m mirror aperture is about 4500 W/m, with about 75% of that energy ({approx} 3400 W/m) reaching the absorber surface. Of the 3400 W/m on the absorber, about 3000 W/m is absorbed into the working fluid while 400 W/m is lost to the environment.

Price, H.; Netter, J.; Bingham, C.; Kutscher, C.; Burkholder, F.; Brandemuehl, M.

2007-03-01

206

Sensitivity of Concentrating Solar Power Trough Performance, Cost and Financing with Solar Advisor Model  

SciTech Connect

A comprehensive solar technology systems analysis model, the Solar Advisor Model (SAM) was developed to support the federal R&D community and the solar industry. This model, developed by staff at NREL and Sandia National Laboratory, is able to model the costs, finances, and performance of concentrating solar power and photovoltaics (PV). Currently, parabolic troughs and concentrating PV are the two concentrating technologies modeled within the SAM environment.

Blair, N.; Mehos, M.; Christensen, C.

2008-03-01

207

Solar thermal aircraft  

SciTech Connect

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

208

Experimental and theoretical study of a solar desalination system located in Cairo, Egypt  

Microsoft Academic Search

The experimental and theoretical study of a solar desalination system located in Cairo, Egypt, is presented in this research. A modification unit is provided to enhance the performance of the solar desalination. The modification unit includes a solar parabolic trough (solar energy concentrator) with focal pipe and simple heat exchanger (serpentine) Oil is selected as working fluid. Oil is flowing

Zeinab S. Abdel-Rehim; Ashraf Lasheen

2007-01-01

209

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

210

Gain Scheduled Control of a Solar Power Plant Tor A. Johansen1  

E-print Network

Gain Scheduled Control of a Solar Power Plant Tor A. Johansen1 , Kenneth J. Hunt2 and Idar Petersen to a pilot-scale solar power plant is described. A eld of parabolic collectors focus the solar radiation onto a tube where oil is pumped through in order to collect the solar power. The control problem is to keep

Johansen, Tor Arne

211

innovati nComponents Makeover Gives Concentrating Solar Power a Boost  

E-print Network

innovati nComponents Makeover Gives Concentrating Solar Power a Boost Parabolic trough technology is the most mature of the various concentrating solar power (CSP) options. But scientists at the National on various components in industrial partnerships with Acciona Solar Power, SkyFuel, Schott Solar, and others

212

General theme report: Working session 2, solar thermal systems  

NASA Astrophysics Data System (ADS)

Currently, over 90 percent of the world's large-scale solar electric energy is generated with concentrating solar thermal power plants. Such plants have the potential to meet many of the world's future energy needs. Research efforts are generally focused on generating electricity, though a variety of other applications are being pursued. Today, the technology for using solar thermal energy is well developed, cost competitive, and in many cases, ready for widespread application. The current state of each of the solar thermal technologies and their applications is reviewed, and recommendations for increasing their use are presented. The technologies reviewed in detail are: parabolic trough systems, central tower systems, and parabolic dish systems.

Alpert, D. J.; Kolb, G. J.

1991-01-01

213

Surface Error Estimation of Pseudo-ParabolicSurface Made by Using Gore Membranes  

NASA Astrophysics Data System (ADS)

In this paper, we describe the surface error of pseudo-parabolic surface, to construct an inflatable parabolic reflector. The gore sheet is generated by cutting the three-dimensional parabolic surface. A scheme of generating the gore sheet is described, and the rms surface error between the parabolic surface and the three-dimensional shape composed of the gore sheets is proposed and formulated. The rms surface error between the parabolic surface and the shape produced by pressurizing the circular membrane is also formulated. Finally, the possibility that the parabolic reflector composed of the gore sheets has high surface accuracy is shown.

Nagata, Tomoko; Ishida, Ryohei

214

Large Parabolic Dish collectors with small gas-turbine, Stirling engine or photovoltaic power conversion systems  

SciTech Connect

A comparison for different solar thermal power plants is presented and demonstrates that the large parabolic dish in association with a gas turbine or a Sterling engine could be a competitive system design in the net power range of 50-1000KW. The important advantages of the Large Parabolic Dish concept compared to the Farm and Tower concept are discussed: concentration ratios up to 5000 and uniform heat flux distribution throughout the day which allow very high receiver temperatures and therefor high receiver efficiency to operate effectively Stirling motors or small gas turbines in the mentioned power range with an overall efficiency of 20 to 30%. The high focal plane concentration leads to the efficient use of ceramic materials for receivers of the next generation, applicable in temperature ranges up to 1,300 /sup 0/C for energy converters. Besides the production of electricity, the system can supply process heat in the temperature range of 100 to 400 /sup 0/C as waste heat from the gas turbo converter and heat at temperature levels from 500 to 900 /sup 0/C (1300 /sup 0/C) directly out of the receiver.

Gehlisch, K.; Heikal, H.; Mobarak, A.; Simon, M.

1982-08-01

215

Rotational Disruption of Comets with Parabolic Orbits  

NASA Astrophysics Data System (ADS)

One of the most fundamental problems in planetary science is the natural lifetime of comets, which is limited by several processes, most notably by spontaneous disruption of the nucleus. While the underlying mechanism is uncertain, rapid rotation is often suspected. To address this problem, I derived the probability of rotational disruption, and investigated it for comets with parabolic orbits as a function of perihelion distance and nucleus size for a range of input parameters. The disruption probability is defined as the ratio of expected change in the rotation rate to the allowable span of the rotation rate, the latter being limited by the critical rotation rate (prograde and retrograde), which I adopted from Davidsson (2001, Icarus 149, 375). The expected change in the rotation rate, resulting from the action of torques generated by mass loss, is calculated following the standard approach (e.g. Drahus et al. 2011, ApJL 734, L4, and ref. therein), but taking into account the suspected decrease of the net torque with an increasing active fraction of the nucleus (Jewitt 1997, EM&P 79, 35; Samarasinha & Mueller 2013, ApJL 775, L10). The sublimation flux is obtained from the standard energy balance equation (e.g. Cowan & AHearn 1979, M&P 21, 155), but I also take into account extinction of sunlight in the dust coma. I find that close to the Sun coma transmission steeply decreases with a decreasing heliocentric distance, resulting in the sublimation flux at a remarkably constant level, and also that coma transmission decreases with an increasing nucleus size, both properties being critically important in the calculation of sublimation flux for large sungrazers. The obtained rotational-disruption probability features several interesting properties. It has a well-defined regime occupied by smaller comets closely approaching the Sun, for which rotational disruption is unavoidable regardless of the original rotation state. Moreover, the probability function offers a very close match to the empirical survival cutoff for long-period comets with perihelia of less than 0.5 AU (Bortle 1991, ICQ 13, 89), independently suggesting that rotational disruption is the primary mechanism responsible for the destruction of comets.

Drahus, Michal

2014-11-01

216

Solar thermionic power systems for terrestrial applications  

Microsoft Academic Search

The results of a feasibility study which showed that a low-temperature, high-efficient thermionic power system can efficiently convert solar energy to electrical energy without heat transport, as required by most solar thermal systems are described. A 3-dimensional (2-axis tracking) 93 sq m parabolic solar concentrator, consisting of mirrors on a foam glass substrate and designed to a concentration ratio (mirror

K. Shimada; M. Swerdling

1977-01-01

217

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

218

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

219

Photogrammetric Measurements of a 12-metre Preloaded Parabolic Dish Antenna  

E-print Network

A 12-metre Preloaded Parabolic Dish antenna, in which the backup structure is formed by preloading its radial and circumferential members, has been designed, built and commissioned by the Raman Research Institute, Bangalore. This paper reports the first-ever photogrammetric measurements of gravity-induced deformation in the primary reflector of an antenna built using this novel concept of preloading the backup structure. Our experience will be of relevance to radio astronomy and deep space network applications that require building lightweight and economical steerable parabolic antennas.

Shankar, N Udaya; Ateequlla, C M; Nayak, Arvind; Krishnan, A; Yogi, M K S; Rao, C Koteshwar; Vidyasagar, K; Jain, Rohit; Mathur, Pravesh; Govinda, K V; Rajeev, R B; Danabalan, T L

2009-01-01

220

Parabolic type semigroups: asymptotics and order of contact  

NASA Astrophysics Data System (ADS)

We study the asymptotic behavior of parabolic type semigroups acting on the unit disk as well as those acting on the right half-plane. We use the asymptotic behavior to investigate the local geometry of the semigroup trajectories near the boundary Denjoy-Wolff point. The geometric content includes, in particular, the asymptotes to trajectories, the so-called limit curvature, the order of contact, and so on. We then establish asymptotic rigidity properties for a broad class of semigroups of parabolic type.

Elin, Mark; Jacobzon, Fiana

2014-09-01

221

Output Feedback Control of Parabolic PDE Systems with Input Constraints1  

E-print Network

by quasi-linear parabolic PDEs. Examples in- clude tubular reactors, packed-bed reactors, and chemical vapor deposition reactors. Parabolic PDE systems typi- cally involve spatial differential operators

Sontag, Eduardo

222

Property estimation using inverse methods for elliptic and parabolic partial differential equations  

E-print Network

In this work we use inverse methods to estimate flow coefficients in both elliptic and parabolic partial differential equations. An algorithm is developed to solve a one layer problem for elliptic and parabolic partial differential equations...

Parmekar, Sandeep

2012-06-07

223

Optical properties of linear parabolic concentrators of large area Experimental results  

NASA Astrophysics Data System (ADS)

A parabolic trough solar concentrator with a 2.5-m aperture has been developed which may be used with both a thermodynamic receiver and a photovoltaic array. The present paper presents results of the measurement of the optical properties of the modular concentrator, which limit its performance in photovoltaic applications. The concentration of the collected energy in the focal zone was monitored by the use of a laser beam to illuminate sections of the trough reflecting surface at various angles of incidence and collector inclinations. A new concentration factor defined as the product of the geometric concentration factor with the cosine of the incidence angle at which the radiation strikes the photocell array was then determined for various sections of the trough as a function of trough aperture. These tests have allowed the definition of the size and shape of a prototype photovoltaic converter currently under construction.

Bellecci, C.; Bonanno, A.; Camarca, M.; Conti, M.; Garofalo, G.; Racalbuto, S.; Visentin, R.

1981-06-01

224

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

225

Application and Operations Concepts of Large Transmit Phased Array of Parabolic Reflectors  

NASA Technical Reports Server (NTRS)

The primary motive for large transmit array of parabolic reflectors, also known as Uplink Array, was to explore alternate methods in order to replace the large 70m antennas of Deep Space Network (DSN) such that the core capability for emergency support to a troubled spacecraft in deep space is preserved. Given that the Uplink Array is a new technology, the focus has always been on its feasibility and phase calibration techniques, which by itself is quite a challenge. It would be interesting to examine, however, what else could be accomplished by the Uplink Array capability other than the emergency support to a troubled spacecraft in deep space. ... The objective of this paper is to discuss a few application scenarios and the corresponding operation concepts, such as lunar positioning system, high EIRP uplink and the synergies with solar radar, and high power RF beams.

Amoozegar, Farid

2006-01-01

226

Wellposedness for a Class of Abstract Nonlinear Parabolic Systems with Time Delay \\Lambda  

E-print Network

Well­posedness for a Class of Abstract Nonlinear Parabolic Systems with Time Delay \\Lambda H and phrases: Nonlinear parabolic distributed parameter systems with delays, existence, uniqueness, variational Abstract We consider a class of abstract nonlinear parabolic systems such as those arising in advanced toxi

227

Focal plane flux distributions produced by solar concentrating reflectors  

NASA Astrophysics Data System (ADS)

A new method is proposed for computing focal plane flux distributions from solar concentrators of parabolic trough, parabolic dish, linear Fresnel, and circular Fresnel geometries. The method is based on efficient numerical equations and allows for the reflecting surface quality and concentrator contour accuracy. Computer implementation of the proposed flux models makes it possible to use mathematical programming techniques that can search a large parameter space for optimum concentrator/absorber designs.

Harris, J. A.; Duff, W. S.

228

Interior Gradient Blow-up in a Semilinear Parabolic Equation  

Microsoft Academic Search

We present a one dimensional semilinear parabolic equation for which the spatial derivative of solutions becomes unbounded in finite time while the solutions themselves remain bounded. In our example the derivative blows up in the interior of the space interval rather than at the boundary, as in earlier examples. In the case of monotone solutions we show that gradient blow-up

Sigurd B. Angenent; Marek Fila

229

Parabolic Anderson model with a finite number of moving catalysts  

E-print Network

Parabolic Anderson model with a finite number of moving catalysts F. Castell, O. G¨un and G- actant" u under the influence of a "catalyst" . In the present paper we focus on the case where of particles A and B. A-particles represent "catalysts", B-particles represent "reactants" and the dynamics

Maillard, Grégory

230

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

231

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

232

Rothe's method for parabolic problems with nonlinear degenerating coefficient  

E-print Network

Rothe's method for parabolic problems with nonlinear degenerating coefficient Volker Pluschke on the solution u. We approximate the problem by semidiscretization in time (Rothe's method) and prove uniform in time (Rothe's method). Here G ae R N , N ?? 2, denotes a simply connected, bounded domain with boundary

233

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

234

GEOMETRIC CHARACTERIZATION OF INTERMITTENCY IN THE PARABOLIC ANDERSON MODEL  

E-print Network

, as t , the overwhelming contribution to the total mass x u(t, x) comes from a slowly increasing number of `islands' which are located far from each other. These `islands' are local regions of those high exceedances of the field and phrases. Parabolic Anderson problem, intermittency, random environment, quenched asymptotics, heat

König, Wolfgang

235

A TWO CITIES THEOREM FOR THE PARABOLIC ANDERSON MODEL  

E-print Network

¨orters Nadia Sidorova Abstract: The parabolic Anderson problem is the Cauchy problem for the heat equation tu the heat equation with random potential on the integer lattice Zd and study the Cauchy problem number of spatially separated regions of small diameter, which are often called the relevant islands

236

Compound parabolic concentrators for narrowband wireless infrared receivers  

E-print Network

for inexpensive, high-speed wireless links has motivated recent interest in infrared free-space communi- cation and hollow compound parabolic concentrators (CPCs), for use in free-space infrared communication receivers that IMIDD infrared links require a high transmitter power and can to!- erate only a small path loss. While

Kahn, Joseph M.

237

Parabolic halite dunes on the Salar de Uyuni, Bolivia  

Microsoft Academic Search

Palaeoenvironmental interpretation in desert and evaporitic sediments is often ambiguous. Consequently, the recognition of primary sedimentary structures that indicate subaerial exposure or shallow marine conditions are therefore of crucial importance when interpreting marginal sedimentary evaporite facies. Parabolic halite dunes, described here for the first time, are observed on the salt crust of the largest salt flat in the world, the

Johan B Svendsen

2003-01-01

238

Compound parabolic concentrator with cavity for tubular absorbers  

DOEpatents

A compond parabolic concentrator with a V-shaped cavity is provided in which an optical receiver is emplaced. The cavity redirects all energy entering between the receiver and the cavity structure onto the receiver, if the optical receiver is emplaced a distance from the cavity not greater than 0.27 r (where r is the radius of the receiver).

Winston, Roland (5217C S. University Ave., Chicago, IL 60615)

1983-01-01

239

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

240

Solar energy conversion system - Four quadrant, two dimension linear solar concentrators  

Microsoft Academic Search

The four-quadrant two-dimensional linear solar concentrator consists of a conventional linear parabolic type concentrator unit, with the addition of top linear lenses to provide direct solar concentration on the top area of focal zone piping. With this geometrical arrangement all four quadrants of a focal zone pipe receive a uniform solar heating effect. The four-quadrant concentrators are advocated for dual

D. A. Kelly

1978-01-01

241

Operational experience from solar thermal energy projects  

NASA Astrophysics Data System (ADS)

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.

1984-03-01

242

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

243

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

244

Receiver\\/reactor concepts for thermochemical transport of solar energy  

Microsoft Academic Search

Thermochemical transport of solar energy based on reversible chemical reactions may be a way to take advantage of the high-temperature capabilities of parabolic dishes, while minimizing pipe network heat loss, since energy is transported at ambient temperatures in chemical form. Receiver\\/Reactor design is a key to making thermochemical transport a reality. In this paper the important parameters for solar receiver

Diver

1987-01-01

245

Receiver\\/reactor concepts for thermochemical transport of solar energy  

Microsoft Academic Search

Thermochemical transport of solar energy based on reversible chemical reactions may be a way to take advantage of the high-temperature capabilities of parabolic dishes, while minimizing pipe network heat loss, since energy is transported at ambient temperatures in chemical form. Receiver\\/Reactor design is a key to making thermochemical transport a reality. In this paper the important parameters for solar receiver

Diver

1986-01-01

246

Exergetic analysis of a solar thermal power system  

Microsoft Academic Search

This communication presents a second law analysis based on an exergy concept for a solar thermal power system. Basic energy and exergy analysis for the system components (viz. parabolic trough collector\\/receiver and Rankine heat engine, etc.) are carried out for evaluating the respective losses as well as exergetic efficiency for typical solar thermal power systems under given operating conditions. It

Narendra Singh; S. C. Kaushik; R. D. Misra

2000-01-01

247

Performance of a direct steam generation solar thermal power plant for electricity production as a function of the solar multiple  

Microsoft Academic Search

This paper describes the influence of the solar multiple on the annual performance of parabolic trough solar thermal power plants with direct steam generation (DSG). The reference system selected is a 50MWe DSG power plant, with thermal storage and auxiliary natural gas-fired boiler. It is considered that both systems are necessary for an optimum coupling to the electricity grid. Although

M. J. Montes; A. Abnades; J. M. Martnez-Val

2009-01-01

248

Linear concentrating solar collector  

SciTech Connect

The present invention relates to a segment of a linear concentrating solar collector which includes two plates distanced from each other and extending parallel to each other; a member connects the plates to each other and holes are bored in each of the plates in a parallel manner along a parabolic curve. A member passes through the holes each holding a small strip made of a reflecting material all strips together forming a parabolic surface. The invention relates also to a collector comprising at least two of each segments and an absorber extending along the focus line of the entire collector. The collector is advantageously provided with horizontal and/or vertical members which ascertains that the collector can follow the position of the sun.

Aharon, N. B.

1985-08-06

249

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

SciTech Connect

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 cooperative effort involving six organizations in four different countries. This multilateral'' project made considerable progress towards a commercially practical collector. One of two basic designs considered employed a heat pipe and an internal metal reflector CPC. We fabricated and tested two large diameter (125mm) borosilicate glass collector tubes to explore this concept. The other design also used a large diameter (125mm) glass tube but with a specially configured internal shaped mirror CPC coupled to a U-tube absorber. Performance projections in a variety of systems applications using the computer design tools developed by the International Energy Agency (IEA) task on evacuated collectors were used to optimize the optical and thermal design. The long-term goal of this work continues to be the development of a high efficiency, low cost solar collector to supply solar thermal energy at temperatures up to 250{degree}C. Some experience and perspectives based on our work are presented and reviewed. Despite substantial progress, the stability of research support and the market for commercial solar thermal collectors were such that the project could not be continued. A cooperative path involving university, government and industrial collaboration remains the most attractive near term option for developing a commercial ICPC.

Winston, R.; O'Gallagher, J.J.

1992-05-31

250

Variation of collector efficiency and receiver thermal loss as a function of solar irradiance  

NASA Astrophysics Data System (ADS)

Efficiency and thermal loss of a parabolic trough concentrating solar collector have been measured for values of solar irradiance between 400 W/sq m and 100 W/sq m. Both parameters are shown to vary significantly with changing solar irradiance. Significant errors can result from improper use of currently published efficiency data.

Dudley, V. E.; Workhoven, R. M.

251

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

252

Solar cooking trends--A preliminary report  

SciTech Connect

This report discusses early results of research on trends in solar cooking worldwide and the key factors in those trends. It is based on household interviews in Belize, Honduras and Nicaragua and mail surveys from scattered individuals and promotion projects worldwide. Household interviews from six more countries will be included in future reports. Early data indicate that where solar cooking has been introduced an immediate, rapid increase in awareness and interest in solar cooking is followed by slow, sustained growth in actual solar cooking two or three years later, after an incubation period. Access to information and affordable materials for the cookers are important. Individual users and promoters both identify similar key elements for effective promotion projects, but in current projects many are often missing. Even so, successes of these small-scale efforts verify the benefits and acceptability of solar cooking to families in many regions, and should encourage much broader promotion efforts. Future reports will explore various economic, technical, cultural and environmental factors in solar cooking use as guides for larger efforts.

Blum, B.L. [Solar Box Cookers International, Sacramento, CA (United States)

1992-12-31

253

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

254

Calculating the Performance of a Solar Reflector  

NASA Technical Reports Server (NTRS)

New method calculates efficiency and useful heat of parabolic solar concentrator. Method uses three-part nomogram, consisting of a main chart and two other components. User enters the nomogram using known factors, then proceeds to plot lines to intercepts on nomogram to find results.

Selcuk, M. K.

1982-01-01

255

Development of a Second-Generation Concentrating Tracking Solar Collector. Technical Progress Report, 20 June-27 December 1978.  

National Technical Information Service (NTIS)

The objective of the work is to develop a second generation concentrating tracking solar collector. The approach combines a parabolic mirror concentrator with a variation of the cylindrical blackbody receiver to provide a minimum concentration ratio of te...

R. W. Miller

1979-01-01

256

Development of a Second-Generation Concentrating Tracking Solar Collector. Technical Progress Report, 28 December 1978-19 June 1979.  

National Technical Information Service (NTIS)

The objective of the work is to develop a second generation concentrating tracking solar collector. The approach combines an array of parabolic trough mirror concentrators each combined with a variation of the cylindrical blackbody receiver to provide a c...

W. D. Antrim

1979-01-01

257

Accelerated stress testing of terrestrial solar cells  

NASA Technical Reports Server (NTRS)

The development of an accelerated test schedule for terrestrial solar cells is described. This schedule, based on anticipated failure modes deduced from a consideration of IC failure mechanisms, involves bias-temperature testing, humidity testing (including both 85-85 and pressure cooker stress), and thermal-cycle thermal-shock testing. Results are described for 12 different unencapsulated cell types. Both gradual electrical degradation and sudden catastrophic mechanical change were observed. These effects can be used to discriminate between cell types and technologies relative to their reliability attributes. Consideration is given to identifying laboratory failure modes which might lead to severe degradation in the field through second quadrant operation. Test results indicate that the ability of most cell types to withstand accelerated stress testing depends more on the manufacturer's design, processing, and worksmanship than on the particular metallization system. Preliminary tests comparing accelerated test results on encapsulated and unencapsulated cells are described.

Lathrop, J. W.; Hawkins, D. C.; Prince, J. L.; Walker, H. A.

1982-01-01

258

Parabolic discounting of monetary rewards by physical effort.  

PubMed

When humans and other animals make decisions in their natural environments prospective rewards have to be weighed against costs. It is well established that increasing costs lead to devaluation or discounting of reward. While our knowledge about discount functions for time and probability costs is quite advanced, little is known about how physical effort discounts reward. In the present study we compared three different models in a binary choice task in which human participants had to squeeze a handgrip to earn monetary rewards: a linear, a hyperbolic, and a parabolic model. On the group as well as the individual level, the concave parabolic model explained most variance of the choice data, thus contrasting with the typical hyperbolic discounting of reward value by delay. Research on effort discounting is not only important to basic science but also holds the potential to quantify aberrant motivational states in neuropsychiatric disorders. PMID:24140077

Hartmann, Matthias N; Hager, Oliver M; Tobler, Philippe N; Kaiser, Stefan

2013-11-01

259

A technique for comparing parabolic trough photovoltaic performance  

NASA Astrophysics Data System (ADS)

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 to provide individual insolation inputs to cell computer models. The analysis, using the Photovoltaic Transient Analysis Program (PV-TAP), led to the selection of the larger trough for the PRDA system. The techniques detailed in this paper can serve as a valuable tool in predicting the output of proposed collector designs. This paper also presents the results of the trade-off and conclusions pertinent to parabolic troughs in general.

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

260

Long-term average performance benefits of parabolic trough improvements  

NASA Astrophysics Data System (ADS)

Various technology advancements in improving the long term average performance of parabolic trough concentrating collectors were analyzed. 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 C. Above 150 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

261

Eigenstate symmetries and information transfer in parabolic quantum reflectors  

NASA Astrophysics Data System (ADS)

We study the quantum mechanical properties of one of the simplest geometrical elements: a parabolic reflector. We study the quantum propagation problem in a two-dimensional mirror, appropriate for electrons on the surface of metals, providing explicit closed solutions for the particle wave functions and the corresponding energy dispersion. Knowledge of nodal lines and distributions highlights the importance of silent and loud regions where quantum amplitude would be small or large. We further analyze the effects of quantum focusing and reflection for an initial pulse originating at the focus of the parabolic reflector. We find two propagation fronts that persist at long times and away from the focus of the parabola; the reflected front has higher amplitude and exhibits a nearly flat distribution moving at constant speed along the focal axis, reminiscent of a typical optical mirror wave front.

Trallero-Giner, C.; Lopez-Richard, V.; Ulloa, S. E.; Marques, G. E.

2009-04-01

262

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

263

Photostimulated Radio Electrical Longitudinal Effect in a Parabolic Quantum Well  

NASA Astrophysics Data System (ADS)

The longitudinal radioelectrical efffect in a parabolic quantum well (PQW) has been studied, based on the quantum kinetic equation for electrons under the action of a linearly polarized electromagnetic wave (EMW) and an intense laser field. Analytic expressions for the density of the current associated with the drag of charge carriers for the case of electron optical phonon scattering is calculated. The dependence of the current density on the intensity F and the frequency O of the laser radiation field, the frequency ? of the linearly polarized EMW field, the frequency of the parabolic potential, the temperature T of the system are obtained. The analytic expressions are numerically evaluated and plotted for a specific quantum wells, GaAs/AlGaAs. All the results of PQW are compared with semiconductors builk and superlattice shows that the difference.

Hung, Bui Duc; Thi Thanh Nhan, Nguyen; Quang Bau, Nguyen; Nhan, Nguyen Vu

2014-09-01

264

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

265

Effective Mobility Model of Graphene Nanoribbon in Parabolic Band Energy  

NASA Astrophysics Data System (ADS)

In this letter, we investigate the transport properties of one-dimensional semiconducting Graphene nanoribbons (GNRs) with parabolic band structure near the Dirac point. The analytical model of effective mobility is developed by using the conductance approach, which differs from the conventional method of extracting the effective mobility using the well-known Matthiessen rule. Graphene nanoribbons conductance model developed was applied in the Drude model to obtain the effective mobility, which then gives nearly close comparison with the experimental data.

Amin, N. A.; Ahmadi, M. T.; Johari, Z.; Mousavi, S. M.; Ismail, R.

266

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

267

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

268

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

Gomez, Jose; Lopez-Moliner, Joan

2013-01-01

269

Piecewise parabolic method (PPM) for gas-dynamical simulations  

Microsoft Academic Search

We present the piecewise parabolic method, a higher-order extension of of Godunov's method. There are several new features of this method which distinguish it from other higher-order Godunov-type methods. We use a higher-order spatial interpolation than previously used, which allows for a steeper representation of discontinuities, particularly contact discontinuities. We introduce a simpler and more robust algorithm for calculating the

P. Corlella; PAUL R. WOODWARD

1984-01-01

270

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

2012-11-30

271

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

NASA Astrophysics Data System (ADS)

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 we 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 focusses 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(s). 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(s)) in the NS-direction which still can be concentrated by a factor of n/sin(23.5 degree(s)). 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, Martin; Goetzberger, Adolf; Blieske, Ulf

1994-09-01

272

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

273

Solar Total Energy at Sandia Labs  

Microsoft Academic Search

The Sandia Laboratories' Solar Total Energy Program is described. This program consists of designing, building, installing, and operating a field of concentrating parabolic trough solar collectors which provide energy at 310 C, a 32-kW organic Rankine cycle power plant, and the heating and cooling equipment to utilize the cascaded, low-temperature energy from the turbine\\/generator. Included in the presentation are descriptions

J. A. Leonard

1976-01-01

274

Midtemperature solar systems test facility predictions for thermal performance based on test data: solar kinetics T-600 solar collector with FEK 244 reflector surface  

SciTech Connect

Sandia National Laboratories, Albuquerque (SNLA), is currently conducting a program to predict the performance and measure the characteristics of commercially available solar collectors that have the potential for use in industrial process heat and enhanced oil recovery applications. The thermal performance predictions for the Solar Kinetics T-600 solar line-focusing parabolic trough collector are presented for three output temperatures at five cities in the US. (WHK)

Harrison, T.D.

1981-04-01

275

Solar disinfection of infectious biomedical waste: a new approach for developing countries.  

PubMed

Poor developing countries cannot afford expensive technologies such as incineration for management of infectious biomedical waste. We assessed solar heating as an alternative technology. We immersed simulated infectious waste with added challenge bacteria in water in a box-type solar cooker, which was left in the sun for 6 h. In 24 sets of observations, the amount of viable bacteria was reduced by about 7 log. We also tested infectious medical waste with a heavy load of bacteria (10(8)-10(9)/g) from our hospital's burn unit for solar heat disinfection in 20 experiments. Our results showed a similar 7 log reduction in the amount of viable bacteria. Solar heating thus seems to be a cheap method to disinfect infectious medical waste in less economically developed countries. PMID:14575975

Chitnis, V; Chitnis, S; Patil, S; Chitnis, D

2003-10-18

276

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

277

Design of a solar power plant for freeze desalination  

Microsoft Academic Search

A solar-powered seawater desalination plant recently began operating in Yanbu, Saudi Arabia. Design and construction were funded by SOLERAS, a joint effort by the United States and Saudi Arabia to further the development and commercialization of the solar energy. The plant consists of 18 parabolic dish solar collectors with a total reflective surface of 1,445 m² and a thermal output

I. Krepchin; R. Torbin

1987-01-01

278

Energy and exergy analyses on a novel hybrid solar heating, cooling and power generation system for remote areas  

Microsoft Academic Search

In this study, a small scale hybrid solar heating, chilling and power generation system, including parabolic trough solar collector with cavity receiver, a helical screw expander and silica gelwater adsorption chiller, etc., was proposed and extensively investigated. The system has the merits of effecting the power generation cycle at lower temperature level with solar energy more efficiently and can provide

H. Zhai; Y. J. Dai; J. Y. Wu; R. Z. Wang

2009-01-01

279

A frequency-independent parabolic log-periodic phased-array antenna  

NASA Astrophysics Data System (ADS)

A frequency-independent phased array antenna made of log-periodic radiators is presented which, in contrast to the Duhamel array, does not employ phase shifters at the antenna inputs to produce radiation in the main direction. The array considered here is a system of radial log-periodic radiators that form a parabolic phased-array antenna. The dipoles of all the radiators having the same size are located along a parabolic line. The operation of the parabolic array at various frequencies is equivalent to that of a series of confocal parabolic mirror antennas excited from a single source.

Veriga, B. A.; Viakhirev, N. I.

1983-08-01

280

Solar economy and technology update  

SciTech Connect

The industry, national, and consumer perspectives on solar power are reviewed. With a 30% increase in dealer/installers, and a 30% attrition rate, about 60% of the participants in the market are ''new kids on the block.'' The installed value of the market was $750 million in 1981. There was a 30% decline in volumes, due to the recession, in 1982. As for the national perspective, solar is labor intensive, and generated a billion dollars worth of jobs. As the DOE has abandoned all but high risk ''core technology'' RandD has faltered some. But desiccant heat pumps, polymer collectors, and parabolic collectors are discussed.

Brotherton, T.K.

1983-06-01

281

Multiscale numerical methods for some types of parabolic equations  

E-print Network

the convergence of the method. Let ? ? Rd be a bounded open set with Lipschitz boundary [2]. Let Y be a unit square (0,1)d in Rd and T0 be a unit interval (0,1) in R. We consider the nonlinear parabolic problem Dtu??div(a(x/??,t/??,u?,Dxu?))+a0(x...? converges to u weakly in Lp(0,T;W1,p0 (?)) as ?? 0, where u is the solution of the homogenized problem Dtu?div(a?(u,Dxu))+a?0(u,Dxu) = f, (2.3) where a?(?,?) and a?0(?,?) are defined by a?(?,?) = integraldisplay T0 integraldisplay Y a...

Nam, Dukjin

2009-05-15

282

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

283

Approximate controllability for nonlinear degenerate parabolic problems with bilinear control  

NASA Astrophysics Data System (ADS)

In this paper, we study the global approximate multiplicative controllability for nonlinear degenerate parabolic Cauchy-Neumann problems. First, we obtain embedding results for weighted Sobolev spaces, that have proved decisive in reaching well-posedness for nonlinear degenerate problems. Then, we show that the above systems can be steered in L2 from any nonzero, nonnegative initial state into any neighborhood of any desirable nonnegative target-state by bilinear piecewise static controls. Moreover, we extend the above result relaxing the sign constraint on the initial data.

Floridia, Giuseppe

2014-11-01

284

Piecewise-parabolic methods for astrophysical fluid dynamics  

SciTech Connect

A general description of some modern numerical techniques for the simulation of astrophysical fluid flow is presented. The methods are introduced with a thorough discussion of the especially simple case of advection. Attention is focused on the piecewise-parabolic method (PPM). A description of the SLIC method for treating multifluid problems is also given. The discussion is illustrated by a number of advection and hydrodynamics test problems. Finally, a study of Kelvin-Helmholtz instability of supersonic jets using PPM with SLIC fluid interfaces is presented.

Woodward, P.R.

1983-11-01

285

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

286

Chemically reacting mixtures in terms of degenerated parabolic setting  

NASA Astrophysics Data System (ADS)

The paper analyzes basic mathematical questions for a model of chemically reacting mixtures. We derive a model of several (finite) component compressible gas taking rigorously into account the thermodynamical regime. Mathematical description of the model leads to a degenerate parabolic equation with hyperbolic deviation. The thermodynamics implies that the diffusion terms are non-symmetric, not positively defined, and cross-diffusion effects must be strongly marked. The mathematical goal is to establish the existence of weak solutions globally in time for arbitrary number of reacting species. A key point is an entropy-like estimate showing possible renormalization of the system.

Mucha, P. B.; Pokorn, M.; Zatorska, E.

2013-07-01

287

Application of solar thermal energy to buildings and industry  

NASA Astrophysics Data System (ADS)

Flat plate collectors and evacuated tube collectors are described, as are parabolic troughs, Fesnel 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 was 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.

Kutscher, C. F.

1981-05-01

288

Dynamic model of a solar thermochemical water-splitting reactor with integrated energy collection and storage  

Microsoft Academic Search

Water-splitting solar thermochemical cycles are important in meeting the challenges of global climate change and limited fossil fuels. However, solar radiation varies in availability, leading to unsteady state operation. We propose a solar receiver-reactor with integrated energy collection and storage. The reactor consists of a double-pipe heat exchanger placed at the focal line of a parabolic trough solar concentrator. Molten

Rong Xu; Theodore F. Wiesner

289

The Piecewise Parabolic Method for Multidimensional Relativistic Fluid Dynamics  

E-print Network

We present an extension of the Piecewise Parabolic Method to special relativistic fluid dynamics in multidimensions. The scheme is conservative, dimensionally unsplit, and suitable for a general equation of state. Temporal evolution is second-order accurate and employs characteristic projection operators; spatial interpolation is piece-wise parabolic making the scheme third-order accurate in smooth regions of the flow away from discontinuities. The algorithm is written for a general system of orthogonal curvilinear coordinates and can be used for computations in non-cartesian geometries. A non-linear iterative Riemann solver based on the two-shock approximation is used in flux calculation. In this approximation, an initial discontinuity decays into a set of discontinuous waves only implying that, in particular, rarefaction waves are treated as flow discontinuities. We also present a new and simple equation of state which approximates the exact result for the relativistic perfect gas with high accuracy. The strength of the new method is demonstrated in a series of numerical tests and more complex simulations in one, two and three dimensions.

A. Mignone; T. Plewa; G. Bodo

2005-05-10

290

Heat and Chemical Exergy Analysis of Parabolic Trough Collector  

Microsoft Academic Search

Emissions of greenhouse gases and other pollutants, derived from the combustion of fossil fuels for heat and electricity generation, can be significantly reduced or even completely eliminated by substituting fossil fuels with a clean energy source, e.g. solar energy. However, solar radiation reaching the earth is diluted, intermittent, and, unequally distributed. These disadvantages can be overcome by converting solar energy

M. ztrk; I. gl; N. zek

2007-01-01

291

The solvability of the first initial-boundary problem for parabolic and degenerate parabolic equations in domains with a conical point  

SciTech Connect

The first initial-boundary problem for second-order parabolic and degenerate parabolic equations is investigated in a domain with a conical or angular point. The means of attack is already known and uses weighted classes of smooth or integrable functions. Sufficient conditions for a unique solution to exist and for coercive estimates for the solution to be obtained are formulated in terms of the angular measure of the solid angle and the exponent of the weight. It is also shown that if these conditions fail to hold, then the parabolic problem has elliptic properties, that is, it can have a nonzero kernel or can be nonsolvable, and, in the latter case, it is not even a Fredholm problem. A parabolic equation and an equation with some degeneracy or a singularity at a conical point are considered. Bibliography: 49 titles.

Degtyarev, Sergey P [Institute of Applied Mathematics and Mechanics, Ukraine National Academy of Sciences, Donetsk (Ukraine)

2010-09-02

292

ERROR ESTIMATES FOR FINITE DIFFERENCE METHODS FOR A WIDE-ANGLE `PARABOLIC' EQUATION  

E-print Network

ERROR ESTIMATES FOR FINITE DIFFERENCE METHODS FOR A WIDE-ANGLE `PARABOLIC' EQUATION G. D. AKRIVIS. wide-angle `parabolic' equation, Underwater Acoustics, finite difference error esti- mates, interface of propagation that may interact strongly with the bottom layers. The most widely known such equation

Akrivis, Georgios

293

Modeling of graphene nano-ribbon Schottky diodes in the parabolic band structure limit  

NASA Astrophysics Data System (ADS)

In this paper we investigate the band structure of graphene nano-ribbons and the current density. A square root approximation shows that the band energy is parabolic in the low energy limit. In this parabolic region charge transport is controlled by the saturation velocity.

Moghaddam, N. S.; Ahmadi, M. T.; Webb, J. F.; Rahmani, M.; Sadegi, H.; Musavi, M.; Ismail, R.

2012-11-01

294

Parabolic geometries and normal Weyl structures First BGG operators and special solutions  

E-print Network

Parabolic geometries and normal Weyl structures First BGG operators and special solutions The comparison map Examples for projective structures Normal Weyl structures and special solutions of first BGG structures & BGG solutions #12;Parabolic geometries and normal Weyl structures First BGG operators

Drmota, Michael

295

THE PARABOLIC FOCAL CONIC : A NEW SMECTIC A DEFECT Ch. S. ROSENBLATT, R. PINDAK,  

E-print Network

1105 THE PARABOLIC FOCAL CONIC : A NEW SMECTIC A DEFECT Ch. S. ROSENBLATT, R. PINDAK, N. A. CLARK structure de ces réseaux sont discutées. Abstract. 2014 The special case of a focal conic defect in which the line discontinuities form a pair of confocal parabolae (a parabolic focal conic) has been observed

Boyer, Edmond

296

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

297

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

298

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

299

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

300

Solar production of industrial process steam. Phase 2: Fabrication and installation  

NASA Astrophysics Data System (ADS)

A solar facility that provides 445 K (345 F) process steam is described. The facility consists of 1070 sq m (11,520 sq ft) of parabolic trough concentrating collectors, an 18,921 1 (5000 gal) flash boiler, and a 20 hp circulating pump. The construction, startup/checkout, costs, and performance of this solar facility are summarized.

Youngblood, S. B.

1981-02-01

301

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

302

Solar production of industrial process steam at Ore-Ida frozen-fried-potato plant  

Microsoft Academic Search

TRW is designing a system for the demonstration of the Solar Production of Industrial Process Steam. Included, besides the Conceptual Design, is an Environmental Impact Assessment and a System Safety Analysis report. The system as proposed and conceptualized consists of an array of 9520 square feet of parabolic trough concentrating solar energy collectors which generate pressurized hot water. The pressurized

J. M. Cherne; G. H. Gelb; J. D. Pinkerton; S. F. Paige

1978-01-01

303

Integrated solar energy system optimization  

NASA Astrophysics Data System (ADS)

The computer program SYSOPT, intended as a tool for optimizing the subsystem sizing, performance, and economics of integrated wind and solar energy systems, is presented. The modular structure of the methodology additionally allows simulations when the solar subsystems are combined with conventional technologies, e.g., a utility grid. Hourly energy/mass flow balances are computed for interconnection points, yielding optimized sizing and time-dependent operation of various subsystems. The program requires meteorological data, such as insolation, diurnal and seasonal variations, and wind speed at the hub height of a wind turbine, all of which can be taken from simulations like the TRNSYS program. Examples are provided for optimization of a solar-powered (wind turbine and parabolic trough-Rankine generator) desalinization plant, and a design analysis for a solar powered greenhouse.

Young, S. K.

1982-11-01

304

OP = HP (1) Estimation of sound source direction using active microphone with parabolic reflection board. by Ryoichi  

E-print Network

. by Ryoichi Takashima, Tetsuya Takiguchi and Yasuo Ariki (Kobe Univ.) Focal point Parabolic surface Sound a (2) Estimation of sound source direction using active microphone with parabolic reflection board source: the front of the parabolic surface or other case Fig. 1 . direct path reflected path O : focal

Takiguchi, Tetsuya

305

Simulation of a solar powered vapor compression desalination system (SPRVCD)  

Microsoft Academic Search

This article is concerned with the analysis of a solar powered vapor compression desalination system. It consists of three loops, namely, a collector loop, a power loop, and a vapor compression desalination loop. The system is operated by a parabolic collector trough of concentration 4 and R11 as a working fluid with an optimum boiler firing temperature of 410°K. A

K. A. Fathalah; M. A. Darwish; S. E. Aly

1983-01-01

306

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

307

Gravitational wave energy spectrum of a parabolic encounter  

NASA Astrophysics Data System (ADS)

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 (10%) provided that the azimuthal and radial orbital frequencies do not differ by more than 10%. For equatorial orbits in the Kerr spacetime, this corresponds to periapse radii of rp?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.

2010-11-01

308

Using parabolic mirrors for complete imaging of apple surfaces.  

PubMed

Automated imaging systems offer the potential to inspect the quality and safety of fruits consumed by the public. One problem that has hindered adoption of automated technologies has been the inability to image the complete surface of an individual fruit. A particular problem is that both the stem and calyx are concave structures. The goal of this project was to examine tradeoffs for using multiple mirrors to image the surface of apples. For testing, individual apples were suspended using two thin wires, mirrors were placed around an apple, and movies were captured at 90 images per sec. Apples were rotated in all dimensions to examine the efficacy of different mirror configurations. It was determined that specific configurations of two, four, or six parabolic concave mirrors could image an entire surface. A configuration using two mirrors and multiple images acquired as apples roll by was also found to be viable. PMID:19433353

Reese, Daniel; Lefcourt, Alan M; Kim, Moon S; Martin Lo, Y

2009-10-01

309

NASTRAN solutions of problems described by simultaneous parabolic differential equations  

NASA Technical Reports Server (NTRS)

NASTRAN solution techniques are shown for a numerical analysis of a class of coupled vector flow processes described by simultaneous parabolic differential equations. To define one physical problem type where equations of this form arise, the differential equations describing the coupled transfers of heat and mass in mechanical equilibrium with negligible mass average velocity are presented and discussed. Also shown are the equations describing seepage when both electrokinetic and hydrodynamic forces occur. Based on a variational statement of the general problem type, the concepts of scalar transfer elements and parallel element systems are introduced. It is shown that adoptation of these concepts allows the direct use of NASTRAN's existing Laplace type elements for uncoupled flow (the heat transfer elements) for treating multicomponent coupled transfer. Sample problems are included which demonstrate the application of these techniques for both steady-state and transient problems.

Mason, J. B.; Walston, W. H., Jr.

1975-01-01

310

Midtemperature solar systems test facility predictions for thermal performance based on test data: Sun-Heet nontracking solar collector  

SciTech Connect

Sandia National Laboratories, Albuquerque (SNLA), is currently conducting a program to predict the performance and measure the characteristics of commercially available solar collectors that have the potential for use in industrial process heat and enhanced oil recovery applications. The thermal performance predictions for the Sun-Heet nontracking, line-focusing parabolic trough collector at five cities in the US are presented. (WHK)

Harrison, T.D.

1981-03-01

311

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

312

Design requirements for interfaces in solar energy conversion technologies  

NASA Astrophysics Data System (ADS)

Candidate materials for improving the durability and economics of solar energy conversion systems (SECS) are reviewed. A 30-yr lifetime is regarded as necessary for solar collector and concentrator materials in order to offset the high initial costs of SECS in parabolic dish, heliostat, parabolic trough, flat plate collector, OTEC, solar cell, and wind turbine configurations. The materials are required to transfer a maximum amount of intercepted energy without degrading from exposure to UV radiation, wind, water, dust, and temperature cycling. Glass and mirrored surfaces for reflecting or refracting optical subsystems are currently made from soda-lime, boro- and aluminosilicate, and must resist chemicals, abrasion, and permeability, and have good strength, flexibility, coefficient of expansion, and Young's modulus. Additional concerns are present in photochemical, solar cell, and in substrata components and systems.

Butler, B. L.

1982-04-01

313

Air Brayton Solar Receiver, phase 2  

NASA Technical Reports Server (NTRS)

An air Brayton solar receiver (ABSR) is discussed. The ABSR consists of a cylindrical, insulated, offset plate fin heat exchanger which is mounted at the focal plane of a fully tracking parabolic solar collector. The receiver transfer heat from the concentrated solar radiation (which impinges on the inside walls of the heat exchanger) to the working fluid i.e., air. The hot air would then e used to drive a small Brayton cycle heat engine. The engine in turn drives a generator which produces electrical energy. Symmetrical and asymmetrical solar power input into the ABSR are analyzed. The symmetrical cases involve the baseline incident flux and the axially shifted incident fluxes. The asymmetrical cases correspond to the solar fluxes that are obtained by reduced solar input from one half of the concentrator or by receiver offset of plus or minus 1 inch from the concentrator optical axis.

Deanda, L. E.

1981-01-01

314

Propagation of hypergeometric laser beams in a medium with a parabolic refractive index  

NASA Astrophysics Data System (ADS)

An expression to describe the complex amplitude of a family of paraxial hypergeometric laser beams propagating in a parabolic-index fiber is proposed. A particular case of a Gaussian optical vortex propagating in a parabolic-index fiber is studied. Under definite parameters, the Gaussian optical vortices become the modes of the medium. This is a new family of paraxial modes derived for the parabolic-index medium. A wide class of solutions of nonparaxial Helmholtz equations that describe modes in a parabolic refractive index medium is derived in the cylindrical coordinate system. As the solutions derived are proportional to Kummers functions, only those of them which are coincident with the nonparaxial Laguerre-Gaussian modes possess a finite energy, meaning that they are physically implementable. A definite length of the graded-index fiber is treated as a parabolic lens, and expressions for the numerical aperture and the focal spot size are deduced. An explicit expression for the radii of the rings of a binary lens approximating a parabolic-index lens is derived. Finite-difference time-domain simulation has shown that using a binary parabolic-index microlens with a refractive index of 1.5, a linearly polarized Gaussian beam can be focused into an elliptic focal spot which is almost devoid of side-lobes and has a smaller full width at half maximum diameter of 0.45 of the incident wavelength.

Kotlyar, V. V.; Kovalev, A. A.; Nalimov, A. G.

2013-12-01

315

Molten-Salt Power Towers: Newly Commercial Concentrating Solar Storage  

Microsoft Academic Search

Molten-salt storage is already commercially available for concentrating solar power (CSP) plants, allowing solar power to be produced on demand and to backup variable renewable sources such as wind and photovoltaics. The first CSP plants to operate commercially with molten-salt storage utilized parabolic trough concentrators, for example, the Andasol-1 plant. A new type of storage plant has now reached commercial

Rebecca I. Dunn; Patrick J. Hearps; Matthew N. Wright

2012-01-01

316

Exact analytic flux distributions for two-dimensional solar concentrators.  

PubMed

A new approach for representing and evaluating the flux density distribution on the absorbers of two-dimensional imaging solar concentrators is presented. The formalism accommodates any realistic solar radiance and concentrator optical error distribution. The solutions obviate the need for raytracing, and are physically transparent. Examples illustrating the method's versatility are presented for parabolic trough mirrors with both planar and tubular absorbers, Fresnel reflectors with tubular absorbers, and V-trough mirrors with planar absorbers. PMID:23842256

Fraidenraich, Naum; Henrique de Oliveira Pedrosa Filho, Manoel; Vilela, Olga C; Gordon, Jeffrey M

2013-07-01

317

Biosignal alterations generated by parabolic flights of small aerobatic aircrafts  

NASA Astrophysics Data System (ADS)

Since the pioneering works of Prof. Strughold in 1948, the aerospace medicine aimed to characterize the modifications induced in the human body by changes in the gravity level. In this respect, it is nowadays well known that one of the most serious problems of these kind of environments is the fluid shift. If this effect is enough severe and persistent, serious changes in the hemodynamic of the brain (cerebral blood flow and blood oxigenation level) appear which could be detected as alterations in the electroencephalogram, EEG [1]. Also, this fluid redistribution, together with the relocation of the heart in the thorax, induces detectable changes in the electrocardiogram, ECG [2]. Other kind of important problems are related with vestibular instability, kinetosis and illusory sensations. In particular since the seventies [3,4] it is known that in parabolic flights and due to eye movements triggered by the changing input from the otholith system, fixed real targets appeared to have moved downward while visual afterimages appeared to have moved upward (oculogravic illusions). In order to cover all the above-mentioned potential alterations, the present work, together with the gravity level, continuously monitors the electroencephalogram, EEG, the electrocardiogram, ECG and the electrooculogram, EOG of a normal subject trying to detect correlations between the different alterations observed in these signals and the changes of gravity during parabolic flights. The small aerobatic aircraft used is a CAP10B and during the flight the subject is located near the pilot. To properly cover all the range of accelerations we have used two sensitive triaxial accelerometers covering the high and low ranges of acceleration. Biosignals have been gathered using a Biopac data unit together with the Acknowledge software package (from Bionic). It is important to finally remark that, due to the obvious difference between the power of the different engines, the accelerometric characteristics of the aerobatic parabolic flights are different from the ones corresponding to the big Airbus-300 of Novespace-CNES-ESA aircraft. In this case, the two episodes of hypergravity reach 1.8g for 3 seconds with 20-25 seconds of low gravity in between whereas the small aerobatic plane reaches 3g level during roughly 2.5 seconds and 8 seconds period of low gravity. This means that the present potential alterations of the human body are more aggressive but also faster. [1] Y. Kawai, M. Doi, A. Setogawa, R. Shimoyama, K. Ueda, Y. Asai, K. Tatebayashi, Effects of Microgravity on Cerebral Hemodynamics, Yonago Acta Medica, 46 (2003) 1-8. [2] E.A.I. Aidu, V.G. Trunov, L.I. Titomir, A. Capderou, P. Vada, Transformation of Vectorcardiogram Due to Gravitation Alteration, Measurement, Science Review, 3 (2003) 29-32. [3] R.J. Von Baumgarten, G. Baldrighi, G.L. Schillinger, O. Harth, R. Thuemler, Vestibular function in the space environment, Acta Astronautica, 2 (1975) 49-58. [4] http://reversiblefigures.blogspot.com.es/p/outreach.html

Simon, M. Jose; Perez-Poch, Antoni; Ruiz, Xavier; Gavalda, Fina; Saez, Nuria

318

PreGarside monoids and groups, parabolicity, amalgamation, and FC property  

E-print Network

We define the notion of preGarside group slightly lightening the definition of Garside group so that all Artin-Tits groups are preGarside groups. This paper intends to give a first basic study on these groups. Firstly, we introduce the notion of parabolic subgroup, we prove that any preGarside group has a (partial) complemented presentation, and we characterize the parbolic subgroups in terms of these presentations. Afterwards we prove that the amalgamated product of two preGarside groups along a common parabolic subgroup is again a preGarside group. This enables us to define the family of preGarside groups of FC type as the smallest family of preGarside groups that contains the Garside groups and that is closed by amalgamation along parabolic subgroups. Finally, we make an algebraic and combinatorial study on FC type preGarside groups and their parabolic subgroups.

Godelle, Eddy

2012-01-01

319

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

E-print Network

A NOTE ON QUASILINEAR PARABOLIC EQUATIONS ON MANIFOLDS CARLO MANTEGAZZA AND LUCA MARTINAZZI A and the function b. Date: October 4, 2010. 1 #12;2 CARLO MANTEGAZZA AND LUCA MARTINAZZI Interchanging covariant

320

On some global well-posedness and asymptotic results for quasilinear parabolic equations  

Microsoft Academic Search

We prove that the quasilinear parabolic initial-boundary value problem (1.1) below is globally well-posed in a class of high order Sobolev solutions, and that these solutions possess compact, regular attractors ast+.

Kevin McLeod; Albert Milani

1996-01-01

321

The blow-up rate for semilinear parabolic problems on general domains  

Microsoft Academic Search

. We derive results on blow-up rates for parabolic\\u000a equations and systems from Fujita-type theorems. We complement a\\u000a previous study by allowing (possibly unbounded) domains with boundary.

Marek Fila; Philippe Souplet

2001-01-01

322

Parabolic pulse generation in a dispersion-decreasing solid-core photonic bandgap Bragg fiber  

NASA Astrophysics Data System (ADS)

We analyze the interplay of nonlinearity and dispersion in a dispersion-decreasing photonic bandgap Bragg fiber as a new platform for generating parabolic pulses. A suitably designed linearly tapered, low-index-contrast, solid-core Bragg fiber - amenable to fabrication by conventional modified chemical vapor deposition technology - is shown to yield stable parabolic pulses. The fiber design was optimized through a simple and accurate transfer-matrix formalism and pulse evolution was studied by the well-known split-step Fourier method. Our study revealed feasibility of generating parabolic pulses in such a dispersion-decreasing Bragg fiber of length as short as 1 m. We have also studied the effect of third order dispersion on generated parabolic pulse, which is an important deteriorating factor in such applications. The effective single-mode operation of the proposed device is achieved through appropriate tailoring of the outer cladding layers.

Nagaraju, B.; Varshney, R. K.; Agrawal, Govind P.; Pal, Bishnu P.

2010-06-01

323

On the singular set of the parabolic obstacle problem Adrien BLANCHET a  

E-print Network

On the singular set of the parabolic obstacle problem Adrien BLANCHET a aCEREMADE, Universit@ceremade.dauphine.fr (Adrien BLANCHET). URL: http ://www.ceremade.dauphine.fr/blanchet (Adrien BLANCHET). Accepted

Blanchet, Adrien

324

Components Makeover Gives Concentrating Solar Power a Boost (Fact Sheet), The Spectrum of Clean Energy Innovation  

SciTech Connect

Parabolic trough technology is the most mature of the various concentrating solar power (CSP) options. But scientists at the National Renewable Energy Laboratory (NREL) continue to make advances on trough systems through innovative research on various components in industrial partnerships with Acciona Solar Power, SkyFuel, Schott Solar, and others. The results are leading to improved system efficiencies and lower costs for CSP plants.

Not Available

2010-12-01

325

Experimental realisation of a mode-locked parabolic Raman fiber oscillator  

Microsoft Academic Search

The generation of self-similar parabolic pulses (similaritons) has so far only been obtained in single-pass Raman amplifier configurations [1, 2], or in rare-earth doped fiber lasers [3, 4]. We report here the first demonstration of a mode-locked parabolic pulse fiber laser, which can potentially be run at any wavelength using Raman gain. This new all-fiber ring similariton laser scheme (cf.

Claude Aguergaray; V. I. Kruglov; D. Mechin; John D. Harvey

2010-01-01

326

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

327

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

328

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

329

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

330

Explicit Nonlinear Finite Element Geometric Analysis of Parabolic Leaf Springs under Various Loads  

PubMed Central

This study describes the effects of bounce, brake, and roll behavior of a bus toward its leaf spring suspension systems. Parabolic leaf springs are designed based on vertical deflection and stress; however, loads are practically derived from various modes especially under harsh road drives or emergency braking. Parabolic leaf springs must sustain these loads without failing to ensure bus and passenger safety. In this study, the explicit nonlinear dynamic finite element (FE) method is implemented because of the complexity of experimental testing A series of load cases; namely, vertical push, wind-up, and suspension roll are introduced for the simulations. The vertical stiffness of the parabolic leaf springs is related to the vehicle load-carrying capability, whereas the wind-up stiffness is associated with vehicle braking. The roll stiffness of the parabolic leaf springs is correlated with the vehicle roll stability. To obtain a better bus performance, two new parabolic leaf spring designs are proposed and simulated. The stress level during the loadings is observed and compared with its design limit. Results indicate that the newly designed high vertical stiffness parabolic spring provides the bus a greater roll stability and a lower stress value compared with the original design. Bus safety and stability is promoted, as well as the load carrying capability. PMID:24298209

Kong, Y. S.; Omar, M. Z.; Chua, L. B.; Abdullah, S.

2013-01-01

331

Uniqueness of complete maximal hypersurfaces in spatially parabolic generalized Robertson-Walker spacetimes  

NASA Astrophysics Data System (ADS)

A new technique for the study of noncompact complete spacelike hypersurfaces in generalized Robertson-Walker (GRW) spacetimes whose fiber is a parabolic Riemannian manifold is introduced. This class of spacetimes allows us to model open universes which extend to spacelike closed GRW spacetimes from the viewpoint of the geometric analysis of the fiber, and which, unlike those spacetimes, could be compatible with the holographic principle. First, under reasonable assumptions on the restriction of the warping function to the spacelike hypersurface and on the hyperbolic angle between the unit normal vector field and a certain timelike vector field, a complete spacelike hypersurface in a spatially parabolic GRW spacetime is shown to be parabolic, and the existence of a simply connected parabolic spacelike hypersurface in a GRW spacetime also leads to the parabolicity of its fiber. Then, all the complete maximal hypersurfaces in spatially parabolic GRW spacetimes are determined in several cases, extending, in particular, to this family of open cosmological models several well-known uniqueness results for the case of spatially closed GRW spacetimes. Moreover, new Calabi-Bernstein problems are solved.

Romero, Alfonso; Rubio, Rafael M.; Salamanca, Juan J.

2013-06-01

332

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

333

Evaluation of aerosolized medications during parabolic flight maneuvers  

NASA Technical Reports Server (NTRS)

The goal was to visually evaluate the effect gravity has on delivery of medications by the use of various aerosol devices. During parabolic flight the same four aerosols were retested as performed in studio ground tests. It appears that the Cetacaine spray and the Ventolin inhaler function without failure during all test. The pump spray (Nostril) appeared to function normally when the container was full, however it appeared to begin to fail to deliver a full mist with larger droplet size when the container was nearly empty. The simple hand spray bottle appeared to work when the container was full and performed progressively worse as the container was emptied. During Apollo flights, it was reported that standard spray bottles did not work well, however, they did not indicate why. It appears that we would also conclude that standard spray bottles do not function as well in zero gravity by failing to produce a normal mist spray. The standard spray bottle allowed the fluid to come out in a narrow fluid stream when held with the nozzle either level or slightly tilted upward.

Lloyd, Charles W.; Martin, William J.; Gosbee, John

1991-01-01

334

High Speed Analysis Of Free Flights With A Parabolic Thruster  

SciTech Connect

A laser-based rangefinder with high temporal resolution, synchronized with a laser burst, is employed for fast on-site analysis of pulsed free flights. Additional high speed recordings from two different angles of view allow for full 3D-reconstruction of the trajectory and calibration of the rangefinder data. This reveals the whole dynamics of the flyer including the lateral and angular impulse coupling components as well as information on the detonation process. The employment of an ignition pin enhances the reproducibility of the momentum coupling due to a more reliable plasma ignition during the flight. The impact of initial lateral offset is studied and shows beam-riding properties of the parabolic craft within a small range. Back-driving forces are derived and compared with the theoretical model. The flight stability is evaluated with respect to the minimization and compensation of the lateral and angular momentum in a hovering experiment. Stable laser acceleration ranges up to 3 m altitude. Ballistic free flights close to the laboratory ceiling at 7.8 m are reported.

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)

2010-05-06

335

Parabolic Anderson model with a finite number of moving catalysts  

E-print Network

We consider the parabolic Anderson model (PAM) which is given by the equation $\\partial u/\\partial t = \\kappa\\Delta u + \\xi u$ with $u\\colon\\, \\Z^d\\times [0,\\infty)\\to \\R$, where $\\kappa \\in [0,\\infty)$ is the diffusion constant, $\\Delta$ is the discrete Laplacian, and $\\xi\\colon\\,\\Z^d\\times [0,\\infty)\\to\\R$ is a space-time random environment that drives the equation. The solution of this equation describes the evolution of a ``reactant'' $u$ under the influence of a ``catalyst'' $\\xi$. In the present paper we focus on the case where $\\xi$ is a system of $n$ independent simple random walks each with step rate $2d\\rho$ and starting from the origin. We study the \\emph{annealed} Lyapunov exponents, i.e., the exponential growth rates of the successive moments of $u$ w.r.t.\\ $\\xi$ and show that these exponents, as a function of the diffusion constant $\\kappa$ and the rate constant $\\rho$, behave differently depending on the dimension $d$. In particular, we give a description of the intermittent behavior of the sys...

Castell, Fabienne; Maillard, Grgory

2010-01-01

336

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

337

High-order parabolic beam approximation for aero-optics  

SciTech Connect

The parabolic beam equations are solved using high-order compact differences for the Laplacians and Runge-Kutta integration along the beam path. The solution method is verified by comparison to analytical solutions for apertured beams and both constant and complex index of refraction. An adaptive 4th-order Runge-Kutta using an embedded 2nd-order method is presented that has demonstrated itself to be very robust. For apertured beams, the results show that the method fails to capture near aperture effects due to a violation of the paraxial approximation in that region. Initial results indicate that the problem appears to be correctable by successive approximations. A preliminary assessment of the effect of turbulent scales is undertaken using high-order Lagrangian interpolation. The results show that while high fidelity methods are necessary to accurately capture the large scale flow structure, the method may not require the same level of fidelity in sampling the density for the index of refraction. The solution is used to calculate a phase difference that is directly compared with that commonly calculated via the optical path difference. Propagation through a supersonic boundary layer shows that for longer wavelengths, the traditional method to calculate the optical path is less accurate than for shorter wavelengths. While unlikely to supplant more traditional methods for most aero-optics applications, the current method can be used to give a quantitative assessment of the other methods as well as being amenable to the addition of more physics.

White, Michael D., E-mail: Michael.White@wpafb.af.mi [Ohio Aerospace Institute, Wright-Patterson Air Force Base, OH 45433-7512 (United States)

2010-08-01

338

Piracetam and fish orientation during parabolic aircraft flight  

NASA Technical Reports Server (NTRS)

Goldfish were flown in parabolic Keplerian trajectories in a KC-135 aircraft to assay both the effectiveness of piracetam as an antimotion sickness drug and the effectiveness of state-dependent training during periods of oscillating gravity levels. Single-frame analyses of infrared films were performed for two classes of responses - role rates in hypogravity or hypogravity orienting responses (LGR) and climbing responses in hypergravity or hypergravity orienting responses (HGR). In Experiment I, preflight training with the vestibular stressor facilitated suppression of LGR by the 10th parabola. An inverse correlation was found between the magnitudes of LGR and HGR. Piracetam was not effective in a state-dependent design, but the drug did significantly increase HGR when injected into trained fish shortly before flight. In Experiment II, injections of saline, piracetam, and modifiers of gamma-aminobutyric acid - aminooxyacetic acid (AOAA) and isonicotinic acid did not modify LGR. AOAA did significantly increase HGR. Thus, the preflight training has a beneficial effect in reducing disorientation in the fish in weightlessness, but the drugs employed were ineffective.

Hoffman, R. B.; Salinas, G. A.; Homick, J. L.

1980-01-01

339

Laminar Incompressible Flow Past Parabolic Bodies at Angles of Attack  

NASA Astrophysics Data System (ADS)

Numerical solutions of a two-dimensional steady laminar incompressible flow over semi-infinite parabolic bodies at angles of attack are obtained. All solutions are found by using a modified numerical approach to solve the time-dependent Navier-Stokes equations. A check of our solutions to those that exist in the literature at zero angle of attack showed excellent agreement. In addition, at zero angle of attack far from the leading edge, an expected correspondence to Blasius flow was found. At large enough angles of attack, the flow separated on the suction surface. In all the cases examined, the flow separation was followed by a reattachment that defined a separation zone. An almost linear increase in the streamwise extent of the separation zone occurred with increasing angle of attack. The separation location and extent of the separation zone was a function of the nose Reynolds number. The results indicated that the shape factor could be used to provide a criterion for separation and reattachment in these cases. The characteristics of the separation zone for this geometry proved to be an excellent basic flow to document the effect of leading-edge flow separation on acoustic receptivity of boundary layer instabilities.

Erturk, Ercan; Corke, Thomas; Haddad, Osamah

2003-11-01

340

Ultrafast control of the internuclear distance with parabolic chirped pulses.  

PubMed

Recently, control over the bond length of a diatomic molecule with the use of parabolic chirped pulses was predicted on the basis of numerical calculations [Chang; et al. Phys. Rev. A 2010, 82, 063414]. To achieve the required bond elongation, a laser scheme was proposed that implies population inversion and vibrational trapping in a dissociative state. In this work we identify two regimes where the scheme works, called the strong and the weak adiabatic regimes. We define appropriate parameters to identify the thresholds where the different regimes operate. The strong adiabatic regime is characterized by a quasi-static process that requires longer pulses. The molecule is stabilized at a bond distance and at a time directly controlled by the pulse in a time-symmetrical way. In this work we analyze the degree of control over the period and elongation of the bond as a function of the pulse bandwidth. The weak adiabatic regime implies dynamic deformation of the bond, which allows for larger bond stretch and the use of shorter pulses. The dynamics is anharmonic and not time-symmetrical and the final state is a wave packet in the ground potential. We show how the vibrational energy of the wave packet can be controlled by changing the pulse duration. PMID:22082170

Chang, Bo Y; Shin, Seokmin; Santamaria, Jesus; Sola, Ignacio R

2012-03-22

341

Geometric visual illusions in microgravity during parabolic flight.  

PubMed

This investigation explores whether the absence of gravitational information in a microgravity environment affects the perception of several classical visual illusions based on the arrangement of horizontal and vertical lines. Because the perception of horizontal and vertical orientation changes in microgravity, our prediction was that the strength of visual illusions based on the arrangement of horizontal and vertical lines would be altered when study participants were free-floating during parabolic flight. The frequency of appearance of reversed-T, Mller-Lyer, Ponzo, and Hering illusions substantially decreased when observers were free-floating, whereas the Zllner and the Poggendorff illusions were not affected. Because the former illusions rely more heavily on perspective cues for generating inaccurate judgments of depth and size, these results suggest an alteration in the role of linear perspective for three-dimensional vision in microgravity. They also confirm that the visual system normally relies on otolith and somatosensory information for providing accurate judgments about the size and distance of objects when presented with planar presentations of geometric figures. PMID:16056146

Villard, Eric; Garcia-Moreno, Francesc Tint; Peter, Nicolas; Clment, Gilles

2005-08-22

342

Solar water disinfection  

SciTech Connect

Non-potable drinking water is a major problem for much of the world`s population. It has been estimated that from 15 to 20 million children under the age of 5 die from diarrheal conditions brought on by infected drinking water every year. This is equivalent to a fully-loaded DC-10 crashing every ten minutes of every day, 365 days a year. Heat is one of the most effective methods of disinfecting drinking water. Using conventional means of heating water (heating on an open-flamed stove) results in an extremely energy-intensive process. The main obstacle is that for areas of the world where potable water is a problem, fuel supplies are either too expensive, not available, or the source of devastating environmental problems (deforestation). The apparatus described is a solar-powered water disinfection device that can overcome most if not all of the barriers that presently limit technological solutions to drinking water problems. It uses a parabolic trough solar concentrator with a receiver tube that is also a counterflow heat exchanger. The system is totally self-contained utilizing a photovoltaic-powered water pump, and a standard automotive thermostat for water flow control. The system is designed for simplicity, reliability and the incorporation of technology readily accessible in most areas of the world. Experiments at the Florida Solar Energy Center have demonstrated up to 2,500 liters of safe drinking water per day with 28 square meters of solar concentrator.

Anderson, R. [Universal Recycled Water Systems, Orlando, FL (United States); Collier, R. [Enerscope, Inc., Merritt Island, FL (United States)

1996-11-01

343

Solar collection  

NASA Astrophysics Data System (ADS)

Solar dishes, photovoltaics, passive solar building and solar hot water systems, Trombe walls, hot air panels, hybrid solar heating systems, solar grain dryers, solar greenhouses, solar hot water worhshops, and solar workshops are discussed. These solar technologies are applied to residential situations.

Cole, S. I.

1984-08-01

344

Reducing the Cost of Thermal Energy Storage for Parabolic Trough Solar Power Plants  

SciTech Connect

Thermal energy storage systems using phase change materials were evaluated for trough systems that use oil, steam, and high temperature salts as heat transfer fluids. A variety of eutectic salts and metal alloys were considered as phase change materials in a cascaded arrangement. Literature values of specific heat, latent heat, density, and other thermophysical properties were used in initial analyses. Testing laboratories were contracted to measure properties for candidate materials for comparison to the literature and for updating the models. A TRNSYS model from Phase 1 was further developed for optimizing the system, including a novel control algorithm. A concept for increasing the bulk thermal conductivity of the phase change system was developed using expanded metal sheets. Outside companies were contracted to design and cost systems using platecoil heat exchangers immersed in the phase change material. Laboratory evaluations of the one-dimensional and three-dimensional behavior of expanded metal sheets in a low conductivity medium were used to optimize the amount of thermal conductivity enhancement. The thermal energy storage systems were compared to baseline conventional systems. The best phase change system found in this project, which was for the high temperature plant, had a projected cost of $25.2 per kWhth, The best system also had a cost that was similar to the base case, a direct two-tank molten salt system.

Gawlik, Keith

2013-06-25

345

Parabolic resonances and instabilities Vered Rom-Kedara)  

E-print Network

or chaotic, depending on the Hamil- tonian H,,x,v... ,,the energy..., the dimension of the system by a small amount ,,e.g. the effect of a meteor on the solar system.... In particular, consider solutions the energy surfaces. Sub- stantially different dynamics appear near singular points or curves on the energy

346

Offset truss hex solar concentrator  

NASA Technical Reports Server (NTRS)

A solar energy concentrator system comprises an offset reflector structure made up of a plurality of solar energy reflector panel sections interconnected with one another to form a piecewise approximation of a portion of a (parabolic) surface of revolution rotated about a prescribed focal axis. Each panel section is comprised of a plurality of reflector facets whose reflective surfaces effectively focus reflected light to preselected surface portions of the interior sidewall of a cylindrically shaped solar energy receiver. The longitudinal axis of the receiver is tilted at an acute angle with respect to the optical axis such that the distribution of focussed solar energy over the interior surface of the solar engine is optimized for dynamic solar energy conversion. Each reflector panel section comprises a flat, hexagonally shaped truss support framework and a plurality of beam members interconnecting diametrically opposed corners of the hexagonal framework recessed within which a plurality of (spherically) contoured reflector facets is disposed. The depth of the framework and the beam members is greater than the thickness of a reflector facet such that a reflector facet may be tilted (for controlling the effective focus of its reflected light through the receiver aperture) without protruding from the panel section.

White, John E. (Inventor); Sturgis, James D. (Inventor); Erikson, Raymond J. (Inventor); Waligroski, Gregg A. (Inventor); Scott, Michael A. (Inventor)

1991-01-01

347

Steam generation via solar heat pipes  

SciTech Connect

This paper presents an experimental set up which uses solar heat pipes to generate process steam. The characteristics of a single parabolic mirror concentrating collector together with the heat pipe tested intensively in the field. Temperature distributions at various points along the heat pipe are measured. By measuring the temperatures at inlet and outlet of the condenser and the water flow rate, the efficiency of the system and the energy that can be used for steam generation can be calculated. A system which can generate 4 kg/hr of steam is designed. It consists of a series of parabolic mirror concentrating collectors, heat pipes with integrated condensers, a storage tank and a water circulating system.

Ismail, K.A.R.; Liu, C.Y.

1983-12-01

348

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

349

The effects of regional insolation differences upon advanced solar thermal electric power plant performance and energy costs  

NASA Technical Reports Server (NTRS)

This paper presents the performance and cost of four 10-MWe advanced solar thermal electric power plants sited in various regions of the continental United States. Each region has different insolation characteristics which result in varying collector field areas, plant performance, capital costs, and energy costs. The paraboloidal dish, central receiver, cylindrical parabolic trough, and compound parabolic concentrator (CPC) comprise the advanced concepts studied. This paper contains a discussion of the regional insolation data base, a description of the solar systems' performances and costs, and a presentation of a range for the forecast cost of conventional electricity by region and nationally over the next several decades.

Latta, A. F.; Bowyer, J. M.; Fujita, T.

1979-01-01

350

Technical and economical system comparison of photovoltaic and concentrating solar thermal power systems depending on annual global irradiation  

Microsoft Academic Search

Concentrating solar thermal power and photovoltaics are two major technologies for converting sunlight to electricity. Variations of the annual solar irradiation depending on the site influence their annual efficiency, specific output and electricity generation cost. Detailed technical and economical analyses performed with computer simulations point out differences of solar thermal parabolic trough power plants, non-tracked and two-axis-tracked PV systems. Therefore,

Volker Quaschning

2004-01-01

351

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

352

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

353

Thermochemical Energy Transport in a 1-MW Industrial-Process-Heat Solar System.  

National Technical Information Service (NTIS)

A small, industrial-process-heat application employing parabolic-dish solar collectors was studied for feasibility using various energy-transport processes. The system delivers 3.6 GJ/h (1 MW, 3.14 MBtu/h) to a single user as 4.14 MPa (600 psig), 400 exp ...

R. G. Nix

1983-01-01

354

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

355

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

356

Pasteurization of naturally contaminated water with solar energy.  

PubMed

A solar box cooker (SBC) was constructed with a cooking area deep enough to hold several 3.7-liter jugs of water, and this was used to investigate the potential of using solar energy to pasteurize naturally contaminated water. When river water was heated either in the SBC or on a hot plate, coliform bacteria were inactivated at temperatures of 60 degrees C or greater. Heating water in an SBC to at least 65 degrees C ensures that the water will be above the milk pasteurization temperature of 62.8 degrees C for at least an hour, which appears sufficient to pasteurize contaminated water. On clear or partly cloudy days, with the SBC facing magnetic south in Sacramento, bottom water temperatures of at least 65 degrees C could be obtained in 11.1 liters of water during the 6 weeks on either side of the summer solstice, in 7.4 liters of water from mid-March through mid-September, and in 3.7 liters of water an additional 2 to 3 weeks at the beginning and end of the solar season. Periodic repositioning of the SBC towards the sun, adjusting the back reflective lid, and preheating water in a simple reflective device increased final water temperatures. Simultaneous cooking and heating water to pasteurizing temperatures was possible. Additional uses of the SBC to pasteurize soil and to decontaminate hospital materials before disposal in remote areas are suggested. PMID:6712206

Ciochetti, D A; Metcalf, R H

1984-02-01

357

Pasteurization of naturally contaminated water with solar energy.  

PubMed Central

A solar box cooker (SBC) was constructed with a cooking area deep enough to hold several 3.7-liter jugs of water, and this was used to investigate the potential of using solar energy to pasteurize naturally contaminated water. When river water was heated either in the SBC or on a hot plate, coliform bacteria were inactivated at temperatures of 60 degrees C or greater. Heating water in an SBC to at least 65 degrees C ensures that the water will be above the milk pasteurization temperature of 62.8 degrees C for at least an hour, which appears sufficient to pasteurize contaminated water. On clear or partly cloudy days, with the SBC facing magnetic south in Sacramento, bottom water temperatures of at least 65 degrees C could be obtained in 11.1 liters of water during the 6 weeks on either side of the summer solstice, in 7.4 liters of water from mid-March through mid-September, and in 3.7 liters of water an additional 2 to 3 weeks at the beginning and end of the solar season. Periodic repositioning of the SBC towards the sun, adjusting the back reflective lid, and preheating water in a simple reflective device increased final water temperatures. Simultaneous cooking and heating water to pasteurizing temperatures was possible. Additional uses of the SBC to pasteurize soil and to decontaminate hospital materials before disposal in remote areas are suggested. PMID:6712206

Ciochetti, D A; Metcalf, R H

1984-01-01

358

Well-posedness of nonlocal parabolic differential problems with dependent operators.  

PubMed

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 C 0 (?,?) (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

359

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

360

Temperature effects on the linear and nonlinear optical absorption coefficient in semi-parabolic quantum wells  

NASA Astrophysics Data System (ADS)

The effects of temperature on the linear and nonlinear optical absorption coeffic ient in semi-parabolic quantum wells are investigated. By the compact density matrix approach, analytical expressions for these optical properties are obtained. Numerical results are used for typical GaAs/AlxGa1-xAs semi-parabolic nanostructure system. In this paper we have presented the behavior of these optical properties as a function of photon energy and inc ident optical intensity considering the effect of temperature. Our results can make a significant contribution both in practical application and in theoretical research.

Kargar, Asghar; Keshavarz, Alireza

2012-09-01

361

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

362

Erlangen Program at Large--2: Inventing a wheel. The parabolic one  

E-print Network

We discuss parabolic versions of Euler's identity e^{it}=cos t + i sin t. A purely algebraic approach based on dual numbers is known to produce a very trivial relation e^{pt} = 1+pt. Therefore we use a geometric setup of parabolic rotations to recover the corresponding non-trivial algebraic framework. Our main tool is Moebius transformations which turn out to be closely related to induced representations of the group SL(2,R). Keywords: complex numbers, dual numbers, double numbers, linear algebra, invariant, computer algebra, GiNaC

Vladimir V. Kisil

2007-07-27

363

Generation of Self-Similar Parabolic Pulses by Designing Normal Dispersion Decreasing Fiber Amplifier as Well as Its Staircase Substitutes  

Microsoft Academic Search

Generation of self-similar parabolic pulse is analytically and numerically demonstrated by designing parabolic index normal dispersion decreasing fiber (NDDF) amplifiers. The pulse transmission is extensively studied for NDDFs in presence of physical gain as well as virtual gain induced by two different dispersion profiles corresponding to two different physical gain coefficients. Here, we introduce the virtual gain arising from the

Dipankar Ghosh; Mousumi Basu; Somenath Sarkar

2009-01-01

364

Theoretical description of the parabolic approximation\\/Fourier split-step method of representing electromagnetic propagation in the troposphere  

Microsoft Academic Search

A theoretical foundation for the use of the parabolic wave equation\\/Fourier split-step method for modeling electromagnetic tropospheric propagation is presented. New procedures are used to derive a scalar Helmholtz equation and to subsequently transform to a rectangular coordinate system without requiring approximations. The assumptions associated with reducing the resulting exact Helmholtz equation to the parabolic wave equation that is used

James R. Kuttler; G. Daniel Dockery

1991-01-01

365

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

366

Solar technology - A whether report  

NASA Astrophysics Data System (ADS)

Progress in the use of solar energy for producing large quantities of electrical power is assessed. The practicality of different applications of solar energy has been demonstrated, and present activity focuses on reducing production costs, enhancing efficiency, and improving reliability. Solar cell production reached 6 MW in 1982, but cuts in government research funding will delay the arrival of cost-competitive photovoltaics for commercial applications in developed countries. Research is expanding on amorphous Si cells, which are cheaper to produce while having lower efficiencies than single crystal cells. An estimated 60,000-80,000 passive solar houses have been constructed since 1978, and work is proceeding on better thermal control in the houses and more elegant storage techniques, such as long-lasting phase change materials. Industrially, a 114-unit array of parabolic concentrators producing 3 MW is providing steam for electricity and processing in a clothing factory. Tests of the 10 MWe Solar One heliostat array power plant in Barstow, CA have encouraged plans for a 100 MWe plant.

Finneran, K.

1983-03-01

367

The design of a solar receiver for a 25-kWe gas turbine engine  

NASA Astrophysics Data System (ADS)

This paper describes a solar receiver designed to be used with a single-point-focus, parabolic concentrator. The receiver accepts the concentrated solar radiation and uses it to heat the working gas of a small, open-cycle gas turbine to about 1500 F (815 C). The receiver employs a high-efficiency, metallic plate-fin heat transfer surface to effect this energy transfer. The thermal and mechanical design features of the receiver are discussed.

Greeven, M.; Coombs, M.; Eastwood, J.

1980-03-01

368

Asymptotic Analysis of a Kernel Estimator for Parabolic SPDEs with Time-Dependent Coefficients  

E-print Network

in Annals of Applied Probability, Vol. 10, No. 4, pp. 1­13, 2000. Abbreviated Title: Kernel estimator Grant DMS-9972016 0 Key words: kernel estimator, stochastic partial differential equations. AMSAsymptotic Analysis of a Kernel Estimator for Parabolic SPDEs with Time-Dependent Coefficients By M

Lototsky, Sergey V.

369

Quasilinear parabolic variational inequalities with multi-valued lower-order terms  

NASA Astrophysics Data System (ADS)

In this paper, we provide an analytical frame work for the following multi-valued parabolic variational inequality in a cylindrical domain : Find and an such that where is some closed and convex subset, A is a time-dependent quasilinear elliptic operator, and the multi-valued function is assumed to be upper semicontinuous only, so that Clarke's generalized gradient is included as a special case. Thus, parabolic variational-hemivariational inequalities are special cases of the problem considered here. The extension of parabolic variational-hemivariational inequalities to the general class of multi-valued problems considered in this paper is not only of disciplinary interest, but is motivated by the need in applications. The main goals are as follows. First, we provide an existence theory for the above-stated problem under coercivity assumptions. Second, in the noncoercive case, we establish an appropriate sub-supersolution method that allows us to get existence, comparison, and enclosure results. Third, the order structure of the solution set enclosed by sub-supersolutions is revealed. In particular, it is shown that the solution set within the sector of sub-supersolutions is a directed set. As an application, a multi-valued parabolic obstacle problem is treated.

Carl, Siegfried; Le, Vy K.

2014-10-01

370

Performance of light sources and radiation sensors under low gravity realized by parabolic airplane flights  

Microsoft Academic Search

A fundamental study was conducted to establish an experimental system for space farming. Since to ensure optimal light for plant cultivation in space is of grave importance, this study examined the performance of light sources and radiation sensors under microgravity conditions created during the parabolic airplane flight. Three kinds of light sources, a halogen bulb, a fluorescent tube, and blue

Hiroaki Hirai; Yoshiaki Kitaya; Takehiro Hirai

2010-01-01

371

Composition of stochastic processes governed by higher-order parabolic and hyperbolic equations  

Microsoft Academic Search

We consider compositions of stochastic processes that are governed by higherorder partial differential equations. The processes studied include compositions of Brownian motions, stable-like processes with Brownian time, Brownian motion whose time is an integrated telegraph process, and an iterated integrated telegraph process. The governing higher-order equations that are obtained are shown to be either of the usual parabolic type or,

Kenneth J. Hochberg; Enzo Orsingher

1996-01-01

372

Two parabolic equations for propagation in layered poro-elastic media  

E-print Network

- media dependent variable formulation,7 which has improved accuracy for layered elastic media.8 While with the exten- sion necessary for range dependence. In this paper, the description of poro-elastic media follows-elastic media. In Sec. III, the parabolic equation for the first new dependent variable formulation is derived

373

MONOTONE DIFFERENCE SCHEMES STABILIZED BY DISCRETE MOLLIFICATION FOR STRONGLY DEGENERATE PARABOLIC EQUATIONS  

E-print Network

illustrate the performance, and gains in CPU time, for the mollified scheme. Applications to initial of degenerate parabolic equations include two-phase flow in porous media, traffic flow, and sedimentation.5) where C and w0 are a parameter and the central weight, respectively, of the discrete mollification

374

PHYSICAL REVIEW A 84, 063805 (2011) Bouncing plasmonic waves in half-parabolic potentials  

E-print Network

opportunities for subwavelength manipulations of polychromatic and ultrashort-pulse plasmons. DOI: 10.1103/PhysPHYSICAL REVIEW A 84, 063805 (2011) Bouncing plasmonic waves in half-parabolic potentials Wei Liu,1 (Received 29 September 2011; published 2 December 2011) We introduce a plasmonic analog for the dynamics

375

Global regularity of solutions of nonlinear second order elliptic and parabolic differential equations  

Microsoft Academic Search

In this work, we consider solutions of the Dirichlet problem for a fully nonlinear elliptic equation in a smooth, bounded domain and of the analogous parabolic problem. Under certain one-sided conditions on the equation, in particular concavity (or convexity) with respect to the second derivatives of the unknown function, Evans [-1] and Krylov [5] proved local second derivative H61der estimates

Gary M. Lieberman

1986-01-01

376

Slow convergence to zero for a parabolic equation with a supercritical nonlinearity  

Microsoft Academic Search

We study the behaviour of solutions of the Cauchy problem for a supercritical semilinear parabolic equation which converge\\u000a to zero from above as t ? ?. We show that any algebraic decay rate slower than the self-similar one occurs for some initial data.

Marek Fila; Michael Winkler; Eiji Yanagida

2008-01-01

377

Rate of convergence to a singular steady state of a supercritical parabolic equation  

Microsoft Academic Search

.We study global positive solutions of a supercritical parabolic equation which converge to a steady state that is singular\\u000a at x = 0. We determine the rate of convergence to the singular steady state in $$L^\\\\infty({\\\\mathbb{R}}^{N} \\\\ B_{\\\

Marek Fila; Michael Winkler

2008-01-01

378

Convergence to a singular steady state of a parabolic equation with gradient blow-up  

Microsoft Academic Search

We study solutions of a parabolic equation which are bounded but whose spatial derivatives blow up in finite time. We establish results on the behavior on the lateral boundary where the singularity occurs and on the rate of convergence to a singular steady state.

Marek Fila; Jari Taskinen; Michael Winkler

2007-01-01

379

Optimal lower bound of the grow-up rate for a supercritical parabolic equation  

Microsoft Academic Search

We study the behavior of solutions of the Cauchy problem for a supercritical semilinear parabolic equation which approach a singular steady state from below as t??. It is known that the grow-up rate of such solutions depends on the spatial decay rate of initial data. We give an optimal lower bound on the grow-up rate by using a comparison technique

Marek Fila; John R. King; Michael Winkler; Eiji Yanagida

2006-01-01

380

Cross polarizing effects of a water film on a parabolic reflector at microwave frequencies  

Microsoft Academic Search

The cross polarizing effects introduced by a uniform water film on the surface of a parabolic reflector are evaluated at 10 and 34 GHz. The reflector is considered to be illuminated by an isotropic linearly polarized source at the focus, but the analysis can be applied for any given primary feed aperture field distribution. The aperture cress polarized field is

PETER A. WATSON; S. I. Ghobrial

1972-01-01

381

Geometrical optical performance studies of a composite parabolic trough with a fin receiver  

NASA Astrophysics Data System (ADS)

The geometrical optical performance characteristics of a composite parabolic trough (CPT) with a fin receiver have been studied. The variation of geometrical concentration ratio with mirror element size and the rim angle of the parent parabola has been studied and the results are presented graphically. The distribution of local concentration ratio over the receiver plane has also been determined for some typical concentrator designs.

Mathur, S. S.; Kandpal, T. C.; Singh, R. N.; Singhal, A. K.

1981-11-01

382

Classical Solutions of Nonautonomous Riccati Equations Arising in Parabolic Boundary Control Problems, II  

SciTech Connect

An abstract linear-quadratic regulator problem over finite time horizon is considered; it covers a large class of linear nonautonomous parabolic systems in bounded domains, with boundary control of Dirichlet or Neumann type. We give the proof of some result stated in [AT5], and in addition we prove uniqueness of the Riccati operator, provided its final datum is suitably regular.

Acquistapace, P. [Dipartimento di Matematica 'L. Tonelli', Universita di Pisa, via Filippo Buonarroti 2, I-56127 Pisa (Italy); Terreni, B. [Dipartimento di Scienza dei Materiali, Universita Statale di Milano, via Emanueli 15, I-20126 Milano (Italy)

2000-03-15

383

The moduli space of germs of generic families of analytic diffeomorphisms unfolding a parabolic fixed  

Microsoft Academic Search

In this paper we describe the moduli space of germs of generic families of analytic diffeomorphisms which unfold a parabolic fixed point of codimension 1. In (11) (and also (15)), it was shown that the Ecalle-Voroninmodulus can be unfolded to give a complete modulus for such germs. The modulus is defined on a ramified sector in the canonical perturbation parameter

C. Christopher; C. Rousseau

384

Modeling of Roughness Effects on Electromagnetic Waves Propagation above Sea Surface using 3D Parabolic Equation  

Microsoft Academic Search

This paper deals with effects of sea surface roughness on electromagnetic waves propagation in a three-dimensional domain. The 3D Parabolic Equation method is used to solve the wave equation. A new approach is presented to model the propagation above rough sea surface. Numerical results of electromagnetic waves propagation are presented to highlight the sea surface roughness influence.

Othmane Benhmammouch; Natacha Caouren; Ali Khenchaf

2009-01-01

385

Local parabolic reference approximation of thermal Feynman path integrals in quantum Monte Carlo simulations  

Microsoft Academic Search

We have developed a new propagator, called the local parabolic reference (LPR), for use in the numerical evaluation of discretized Feynman path integrals by Metropolis Monte Carlo simulations. The form of the propagator is motivated by fitting a local quadratic reference potential (with positive, negative or zero curvature) to the potential energy surface of interest, and constructing the exact propagator

Cecilia E. Chao; Hans C. Andersen

1997-01-01

386

Critical epidemics, random graphs and Brownian motion with a parabolic drift  

E-print Network

Critical epidemics, random graphs and Brownian motion with a parabolic drift Remco van der Hofstad distribution of the SIR epidemic model in the critical regime. Using the integral representation of Martin of the normalized Brownian excursion area in terms of Airy functions. Key words: SIR epidemics models, final size

387

Reflection and scattering of acoustic rays computed for parabolic ice keel models  

Microsoft Academic Search

Coefficients are computed for ray reflection and scattering from a model of a set of keels. The model is a collection of parallel ice keels that are of parabolic cross section. The size of the keels and the spacing between them are drawn from random distributions. The keels are also widened by a random factor to simulate oblique incidence on

D. F. Gordon

1988-01-01

388

Reflection and Scattering of Acoustic Rays Computed for Parabolic Ice Keel Models.  

National Technical Information Service (NTIS)

Coefficients are computed for ray reflection and scattering from a model of a set of keels. The model is a collection of parallel ice keels that are of parabolic cross section. The size of the keels and the spacing between them are drawn from random distr...

D. F. Gordon

1988-01-01

389

Global Extrapolations of Numerical Methods for Solving a Parabolic Problem with Non Local Boundary Conditions  

Microsoft Academic Search

A family of numerical methods is developed for the numerical solution of a linear parabolic problem with boundary conditions containing integrals over the interior of the interval. The methods are seen to evolve from first- and second-order rational approximants to an exponential function in a recurrence relation. Global extrapolation procedures in space only and in both space and time are

Abdesslam Boutayeb; Abdelaziz Chetouani

2003-01-01

390

Parabolized stability equation models for predicting large-scale mixing noise of turbulent round jets  

E-print Network

speed jets remain challenging and computationally expensive. On the other hand, numerical jet noiseParabolized stability equation models for predicting large-scale mixing noise of turbulent round jets D. Rodr´iguez1 , A. Samanta1 , A. V. G. Cavalieri2 , T. Colonius1§ and P. Jordan2¶ 1 Department

Colonius, Tim

391

Parabolic Modeling of the Major Temporal Arcade in Retinal Fundus Images  

Microsoft Academic Search

Monitoring measurements of the openness of the major temporal arcade (MTA) and how they change over time could facilitate improved diagnosis and optimized treatment of retinopathy. We propose methods for the detection, modeling, and measurement of the openness of the MTA, including Gabor filters to detect retinal vessels and the Hough transform to detect and parameterize parabolic forms. Results obtained

Faraz Oloumi; Rangaraj M. Rangayyan; Anna L. Ells

2012-01-01

392

Correlation-length bounds, and estimates for intermittent islands in parabolic SPDEs  

E-print Network

Correlation-length bounds, and estimates for intermittent islands in parabolic SPDEs Daniel Conus Abstract We consider the nonlinear stochastic heat equation in one dimension. Under some conditions bound on the length of the "islands," the regions of large values. These results are obtained

Khoshnevisan, Davar

393

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.

394

Imaging by parabolic refractive lenses in the hard X-ray range  

Microsoft Academic Search

The manufacture and properties of compound refractive lenses (CRLs) for hard X-rays with parabolic profile are described. These novel lenses can be used up to60 keV. A typical focal length is 1 m. They have a geometrical aperture of 1 mm and are best adapted to undulator beams at synchrotron radiation sources. The transmission ranges from a few % in

Bruno Lengeler; Christian Schroer; Johannes Tummler; Boris Benner; Matthias Richwin; Anatoly Snigirev; Irina Snigirevab; Michael Drakopoulosb

1999-01-01

395

REMARKS ON THE DIRICHLET AND STATE-CONSTRAINT PROBLEMS FOR QUASILINEAR PARABOLIC EQUATIONS  

Microsoft Academic Search

We prove two difierent types of comparison results be- tween semicontinuous viscosity sub- and supersolutions of the general- ized Dirichlet problem (in the sense of viscosity solutions theory) for quasilinear parabolic equations: the flrst one is an extension of the Strong Comparison Result obtained previously by the second author for annular domains, to domains with a more complicated geometry. The

Guy Barles

2003-01-01

396

Nonlinear parabolic equation model for finite-amplitude sound propagation over porous ground layers  

E-print Network

to simulate weakly nonlinear sound propagation within an inhomoge- neous medium. For this method to be suited equation (NPE) model is used to simulate finite- amplitude sound propagation. This method has first beenNonlinear parabolic equation model for finite-amplitude sound propagation over porous ground layers

Paris-Sud XI, Université de

397

Nonlinear parabolic equation model for finite-amplitude sound propagation over porous ground layers  

E-print Network

simulating weakly nonlinear sound propagation within an inhomogeneous medium. For this method to be suited) model is used to simulate finite amplitude sound propagation. This method has first been developed by McNonlinear parabolic equation model for finite-amplitude sound propagation over porous ground layers

Paris-Sud XI, Université de

398

Sensitivity analysis and computational uncertainty with applications to control of nonlinear parabolic partial differential equations  

Microsoft Academic Search

In this paper we illustrate how sensitivities can be used to provide a practical precursor to dynamic transitions and numerical uncertainty in parameterized nonlinear parabolic partial differential equations. In particular, we focus on reaction-diffusion equations and provide numerical examples to illustrate the ideas and to suggest how one might use sensitivities to address computational uncertainty.

John A. Burns; Lisa G. Davis

2008-01-01

399

Sound propagation over an irregular terrain with complex meteorological effects using the parabolic equation model  

Microsoft Academic Search

Sound impact of road and railway infrastructures are more and more severely regulated by European laws: acceptable thresholds in emission and reception are decreasing. This implies to develop propagation models able to take many phenomena into account at the same time (meteorology, uneven ground, impedances discontinuities...). The parabolic equation (PE) is one of those numerical methods. Its main purpose is

F. Aballa; J. Defrance

400

On a Nonlinear, Nonlocal Parabolic Problem with Conservation of Mass, Mean and Variance  

Microsoft Academic Search

In this paper we prove that the steepest descent of certain porous-medium type functionals with respect to the quadratic Wasserstein distance over a constrained (but not weakly closed) manifold gives rise to a nonlinear, nonlocal parabolic partial differential equation connected to the study of the asymptotic behavior of solutions for filtration problems. The result by Carlen and Gangbo on constrained

A. Tudorascu; M. Wunsch

2011-01-01

401

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

402

FULLY PARABOLIC KELLER-SEGEL MODEL FOR CHEMOTAXIS WITH PREVENTION OF OVERCROWDING  

E-print Network

systems have been labeled with the term chemotaxis, such as the bacteria Escherichia Coli, or the amoebaeFULLY PARABOLIC KELLER-SEGEL MODEL FOR CHEMOTAXIS WITH PREVENTION OF OVERCROWDING Marco Di`a degli Studi dell'Aquila, Facolt`a di Ingegneria Piazzale E. Pontieri, I-67040 - Monteluco di Roio - L

Di Francesco, Marco

403

Coupled Parabolic and Hyperbolic Equations Modeling AgeDependent Epidemic Dynamics with Nonlinear Diffusion*  

E-print Network

is the density of total population. It is clear that in order to take this diffusion effect into account, we need Yong 2 Abstract. This paper considers a system of coupled second order parabolic and first order by v(x; t). In this paper, we do not consider the birth and the natural death. Such a mixed situation

404

An efficient approach for solving a class of nonlinear 2D parabolic PDEs  

Microsoft Academic Search

We consider a class of nonlinear 2D parabolic equations that allow for an efficient application of an operator splitting technique and a suitable linearization of the discretized problem. We apply our scheme to study the finite extinction phenomenon for the porous-medium equation with strong absorption. A comparison of accuracy and computational efficiency of the resulting algorithms for several test problems

Dongjin Kim; Wlodek Proskurowski

2004-01-01

405

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

NASA Astrophysics Data System (ADS)

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.

2013-03-01

406

The polarimetric observation facility at the Medicina 32 m parabolic antenna  

NASA Astrophysics Data System (ADS)

We describe the wideband analog polarimeter made at the Medicina radio observatory usable with the receivers of our 32 m parabolic antenna. The principle under which the electronics was designed as well as the circuit realization will be showed, together with the description of the software made to manage the observations and the off-line processing of the data acquired. .

Orfei, Alessandro; Roma, Mauro

2002-03-01

407

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.

408

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 ...

409

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

410

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

411

Utility-Scale Concentrating Solar Power and Photovoltaic Projects: A Technology and Market Overview  

SciTech Connect

Over the last several years, solar energy technologies have been, or are in the process of being, deployed at unprecedented levels. A critical recent development, resulting from the massive scale of projects in progress or recently completed, is having the power sold directly to electric utilities. Such 'utility-scale' systems offer the opportunity to deploy solar technologies far faster than the traditional 'behind-the-meter' projects designed to offset retail load. Moreover, these systems have employed significant economies of scale during construction and operation, attracting financial capital, which in turn can reduce the delivered cost of power. This report is a summary of the current U.S. utility-scale solar state-of-the-market and development pipeline. Utility-scale solar energy systems are generally categorized as one of two basic designs: concentrating solar power (CSP) and photovoltaic (PV). CSP systems can be further delineated into four commercially available technologies: parabolic trough, central receiver (CR), parabolic dish, and linear Fresnel reflector. CSP systems can also be categorized as hybrid, which combine a solar-based system (generally parabolic trough, CR, or linear Fresnel) and a fossil fuel energy system to produce electric power or steam.

Mendelsohn, M.; Lowder, T.; Canavan, B.

2012-04-01

412

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

413

Projected techno-economic improvements for advanced solar thermal power plants  

NASA Technical Reports Server (NTRS)

The projected characteristics of solar thermal power plants (with outputs up to 10 MWe) employing promising advanced technology subsystems/components are compared to current (or pre-1985) steam-Rankine systems. Improvements accruing to advanced technology development options are delineated. The improvements derived from advanced systems result primarily from achieving high efficiencies via solar collector systems which (1) capture a large portion of the available insolation and (2) concentrate this captured solar flux to attain high temperatures required for high heat engine/energy conversion performance. The most efficient solar collector systems employ two-axis tracking. Attractive systems include the central receiver/heliostat and the parabolic dish.

Fujita, T.; Manvi, R.; Roschke, E. J.

1979-01-01

414

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

415

Solar-thermal electric - Focal point for the desert sun  

NASA Astrophysics Data System (ADS)

The applications of solar thermal systems are explored, including flat plate and line-focus collectors, and parabolic and heliostat point focus electrical generators. The first U.S. 10MWe solar tower power plant, Solar One, is due to begin operational testing in 1982, while five other projects are under way in Europe and Japan. Mention is made of the use of solar thermal generators as repowering plants, used to preheat steam for conventional gas and oil fueled power plants. Thermal storage methods, such as molten salt, hot rocks, and hot oil are reviewed, as are Brayton and Rankine cycle heat transfer systems. The Brayton cycle will be tested in a hybrid scheme with a fossil fuel burning gas generator which will supplement the output from the solar thermal section.

van Atta, D.

1981-12-01

416

HIGH FLUX CENTRAL RECEIVERS OF MOLTEN SALTS FOR THE NEW GENERATION OF COMMERCIAL STAND ALONE SOLAR POWER PLANTS  

Microsoft Academic Search

Molten salt technology represents nowadays the most cost-effective technology for electricity generation for stand-alone Solar Power Plants. Although this technology can be applied to both concentrating technologies, Parabolic Through and Central Receiver Systems (CRS), CRS technology can take advantages from its high concentration, allowing to work at high temperatures and therefore with a reduction in the size and cost of

Jess M. Lat; Manuel Rodrguez; Mnica lvarez de Lara

417

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

418

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

419

Mild solution to parabolic Anderson model in Gaussian and Poisson potential  

NASA Astrophysics Data System (ADS)

We consider the parabolic Anderson model in a special random homogeneous potential that is generated by the Gaussian and Poisson random medium together. In our model, the coefficient V(x) is not Hlder continuous with positive probability, and thus the model is unlikely to have a path-wise solution. We construct a mild solution for the parabolic Anderson model with random potential of the form -V(x)=-int _{{R}^d}K(y-x)[? (dy)+W(dy)], where ? and W denote the independent standard Poisson point process and centred Gaussian field, respectively. The case where the potential switches in sign and the Poisson field is absent is handled as well.

Han, Yuecai; Zhang, Liwei

2013-10-01

420

Low-temperature IPH parabolic troughs: Design variations and cost-reduction potential  

NASA Astrophysics Data System (ADS)

Parabolic trough concentrating collectors which have improved in performance and reliability and development of its components which was tailored to meeting instantaneous collector performance goals at an operating temperature of 315(0)C (600(0)F) are discussed. Although this strategy resulted in advanced component designs and excellent collector performance at 315(0)C, it has also necessitated stringent, expensive component design requirements. Near term parabolic trough collector systems are too expensive to compete widely with conventional fossil fuel systems. The reduction of collector costs with lower temperature designs is described. Industrial process heating energy use at below 150(0)C (300(0)F) is over five times greater than that at from 200(0) to 315(0)C (400(0)F to 600(0)F). Component designs for lower temperatures are considered, including less rigid, lighter weight concentrators; alternative concentrator constructions; larger receivers; and multiple row drive systems.

Gee, R. C.

1983-11-01

421

Image quality in an optical system operating in partially coherent light: effect of parabolic motion.  

PubMed

Results of investigations on an optical system performance as affected by parabolic image motion have been presented in graphic form. The analysis has been performed using Schell's theorem, which occurs in the theory of partial coherence, under the assumption of scalar diffraction theory. Diffraction figure broadening along the direction of motion has been plotted for besinc and Gaussian forms of coherence functions across the circular aperture. Results of the present paper in case of besinc correlation have been shown to be identical with the diffraction images of uniform incoherent bright circular disks in the presence of parabolic motion. Hence the analysis of the present paper is also useful for persons engaged in work concerning aerial reconnaissance etc. PMID:20165367

Gupta, P C; Singh, K

1976-09-01

422

Modeling Rayleigh and Stoneley waves and other interface and boundary effects with the parabolic equation.  

PubMed

An improved approach for handling boundaries, interfaces, and continuous depth dependence with the elastic parabolic equation is derived and benchmarked. The approach is applied to model the propagation of Rayleigh and Stoneley waves. Depending on the choice of dependent variables, the operator in the elastic wave equation may not factor or the treatment of interfaces may be difficult. These problems are resolved by using a formulation in terms of the vertical displacement and the range derivative of the horizontal displacement. These quantities are continuous across horizontal interfaces, which permits the use of Galerkin's method to discretize in depth. This implementation extends the capability of the elastic parabolic equation to handle arbitrary depth dependence and should lead to improvements for range-dependent problems. PMID:16018454

Jerzak, Wayne; Siegmann, William L; Collins, Michael D

2005-06-01

423

Modeling Rayleigh and Stoneley waves and other interface and boundary effects with the parabolic equation  

NASA Astrophysics Data System (ADS)

An improved approach for handling boundaries, interfaces, and continuous depth dependence with the elastic parabolic equation is derived and benchmarked. The approach is applied to model the propagation of Rayleigh and Stoneley waves. Depending on the choice of dependent variables, the operator in the elastic wave equation may not factor or the treatment of interfaces may be difficult. These problems are resolved by using a formulation in terms of the vertical displacement and the range derivative of the horizontal displacement. These quantities are continuous across horizontal interfaces, which permits the use of Galerkin's method to discretize in depth. This implementation extends the capability of the elastic parabolic equation to handle arbitrary depth dependence and should lead to improvements for range-dependent problems. .

Jerzak, Wayne; Siegmann, William L.; Collins, Michael D.

2005-06-01

424

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

425

Theoretical Design of Normal Dispersion Decreasing Fiber Amplifier to Obtain Self-Similar Parabolic Pulses and Its Practical Aspects  

Microsoft Academic Search

The evolution of self-similar parabolic pulses is demonstrated by designing a parabolic index dispersion decreasing fiber amplifier with normal dispersion (ND-DDF amplifier), with inclusion of the variation of nonlinear factor (gamma) with distance. The pulse transmission is extensively studied for the proposed ND-DDF in presence of external gain as well as virtual gain induced by its dispersion profile. The output

Dipankar Ghosh; Mousumi Basu

2008-01-01

426

An Immersed Boundary Method for a Parabolic Problem with Nonstandard Moving Source  

NASA Astrophysics Data System (ADS)

In the present work the numerical solution of a mean-field model for dynamical formation of the price of some good is considered. The model leads to a parabolic equation with non-standard moving sources. On an uniform mesh the Immersed Boundary Method is proposed. For solving the nonsymmetric linear system a numerical algorithm is also developed. Numerical experiments confirm that the difference scheme is of second order in both mesh parameters h and ?.

Kandilarov, J.; Vulkov, L.

2009-11-01

427

ASYMPTOTIC BEHAVIOR OF SOLUTIONS TO NONLINEAR PARABOLIC EQUATION WITH NONLINEAR BOUNDARY CONDITIONS  

Microsoft Academic Search

We show that solutions of a nonlinear parabolic equation of sec- ond order with nonlinear boundary conditions approach zero as t approaches infinity. Also, under additional assumptions, the solutions behave as a function determined here. aij(x) = aji(x), is the exterior normal unit vector on @, fx,t(s) = f(x,t,s) and gx,t(s) = g(x,t,s) are positive, increasing and convex functions for

EODORE K. BONI; DIABATE NABONGO

428

Broadband seismo-acoustic modeling in range-dependent layered media using the parabolic equation method  

Microsoft Academic Search

We present an efficient broadband modeling capability based on synthesizing solutions of the frequency-domain wave equation computed using the wide-angle parabolic equation (PE) method. The PE [a version of NRL's Range-dependent Acoustic Model (RAM)] takes into account recent advances for handling range-varying layer thicknesses, compression and shear waves, and surface\\/interfacial waves (Rayleigh, Stoneley). The technique allows for multiple sources on

David C. Calvo; Michael D. Collins

2005-01-01

429

Parabolic Wave Equation Method Applied to the Tropospheric Ducting Propagation Problem: A Survey  

Microsoft Academic Search

A survey is made of one of the most widely used approximation methods in the wave propagation studiesthe parabolic wave equation methodapplied for the specific case of microwave propagation assessment under tropospheric ducting conditions. A brief review of the methods for tropospheric refractivity profiling, the average refractivity modeling, and the applicability of the often-assumed lateral homogeneity of the refractivity is

I. Sirkova; M. Mikhalev

2006-01-01

430

Modification of the focused field in a parabolic index medium by slow axial tapering  

NASA Astrophysics Data System (ADS)

The effect of slow axial tapering on the three-dimensional structure of the light distribution at the foci of a parabolic index medium is investigated. The approach is based on an adiabatic local mode representation of the field and leads to simple expressions for the field distribution and intensity widths, for any taper shape provided it satisfies a slowness criterion. This slowness criterion unifies the results given here with previously published work.

Bertilone, Derek

1988-05-01

431

Classical Solutions of Nonautonomous Riccati Equations Arising in Parabolic Boundary Control Problems  

SciTech Connect

An abstract linear-quadratic regulator problem over finite time horizon is considered; it covers a large class of linear nonautonomous parabolic systems in bounded domains, with boundary control of Dirichlet or Neumann type. The associated differential Riccati equation is studied from the point of view of semigroup theory; it is shown to have a classical, explicitly represented solution for very general final data; weighted Hoelder regularity results for the optimal pair are deduced.

Acquistapace, P. [Dipartimento di Matematica 'L. Tonelli', Universita di Pisa, via Filippo Buonarroti 2, I-56127 Pisa (Italy); Terreni, B. [Dipartimento di Scienza dei Materiali, Universita Statale di Milano, via Emanueli 15, I-20126 Milano (Italy)

1999-05-15

432

Dirichlet boundary control problems for parabolic equations with quadratic cost: Analyticity and riccati's feedback synthesis  

Microsoft Academic Search

Riccati type feedback synthesis of optimal controls for Dirichlet boundary parabolic equations is considered. The functional cost penalizes the L2 -energy over [0,T] of state and control action u and also final state y(T) at t=T. This latter fact, makes the functional cost discontinuous on the space of admissible controls: L2(); =[0T] . After overcoming some technical difficulties related

Irena Lasiecka; Roberto Triggiani

433

Hybrid\\/mixed assumed stress element for anisotropic laminated elliptical and parabolic shells  

Microsoft Academic Search

A variety of elliptical\\/parabolic dome type structures are used in important aerospace and civil structural systems such as underwater vehicles, stadium covers, exhibition halls, auditoriums and museum halls. For the analysis of such structures, a shear deformable four-noded finite element based on a hybrid\\/mixed assumed stress is presented in this paper. The element called iHES (improved Hybrid and Enhanced Shell

Kyoung-Sik Chun; Samuel Kinde Kassegne; Berhanu Kebede Wondimu

2009-01-01

434

Conditional stability and uniqueness for determining two coefficients in a hyperbolic-parabolic system  

NASA Astrophysics Data System (ADS)

We study the inverse problem of determining two spatially varying coefficients in a thermoelastic model with the following observation data: displacement in a subdomain ? satisfying ????? along a sufficiently large time interval, both displacement and temperature at a suitable time over the whole spatial domain. Based on a Carleman estimate on the hyperbolic-parabolic system, we prove the Lipschitz stability and the uniqueness for this inverse problem under some a priori information.

Wu, Bin; Liu, Jijun

2011-07-01

435

Magneto-optical absorption in an overfilled parabolic quantum well. II. In-plane field  

NASA Astrophysics Data System (ADS)

We extend our study of the far-infrared optical-absorption spectrum of electrons confined in an imperfect parabolic quantum well to the case of in-plane magnetic field, where the spectrum is in general continuous. Using periodic boundary conditions and the random-phase approximation, we obtain good agreement with experiment over a magnetic-field range of 5-14 T.

Dempsey, Jed; Halperin, B. I.

1993-02-01

436

COMPLETE LOCALISATION IN THE PARABOLIC ANDERSON MODEL WITH PARETO-DISTRIBUTED POTENTIAL  

E-print Network

for the heat equation tu(t, z) = u(t, z) + (z)u(t, z) on (0, ) ? Zd with random potential ((z): z Zd ). We and main results 1.1 The parabolic Anderson model and intermittency We consider the heat equation, Feynman-Kac formula. 1 #12;2 WOLFGANG K¨ONIG, PETER M¨ORTERS, AND NADIA SIDOROVA islands. This effect

437

Stabilization of solutions of quasilinear second order parabolic equations in domains with non-compact boundaries  

SciTech Connect

The first mixed problem with homogeneous Dirichlet boundary condition and initial function with compact support is considered for quasilinear second order parabolic equations in a cylindrical domain D=(0,{infinity})x{Omega}. Upper bounds are obtained, which give the rate of decay of the solutions as t{yields}{infinity} as a function of the geometry of the unbounded domain {Omega} subset of R{sub n}, n{>=}2. Bibliography: 18 titles.

Karimov, Ruslan Kh [Institute of Applied Research, Sterlitamak (Russian Federation); Kozhevnikova, Larisa M [Sterlitamak State Pedagogical Academy, Sterlitamak (Russian Federation)

2010-11-11

438

Evaluation of the vestibular evoked myogenic potential during parabolic flight in humans  

Microsoft Academic Search

The purpose of this study was to investigate how gravity affects the vestibular evoked myogenic potential (VEMP). Eight healthy\\u000a subjects (seven men, one woman; age range 1945years) participated in experiments in which three different gravity levels\\u000a [microgravity (MG), normal gravity (NG), and hypergravity (HG)] were imposed during a parabolic flight procedure. The VEMP\\u000a was evoked in response to an intense

Hideo Shojaku; Yukio Watanabe; Masahito Tsubota; Naomi Katayama

2008-01-01

439

Real-Time Video-Microscopy of Migrating Immune Cells in Altered Gravity During Parabolic Flights  

Microsoft Academic Search

In our project we developed a technical equipment which allows to visualize migration of cells in real-time video-microscopy\\u000a during altered gravity conditions of NOVESPACE Airbus A300 ZERO-G parabolic flights. For validation of the experimental device\\u000a we have used fast moving human neutrophils as example, because their migration is fundamental to keep the organism under immunological\\u000a surveillance. Their migration is indispensable

Kerstin Lang; Carina Strell; Bernd Niggemann; Kurt S. Znker; Andre Hilliger; Frank Engelmann; Oliver Ullrich

2010-01-01

440

The relative isoperimetric inequality on a conformally parabolic manifold with boundary  

SciTech Connect

For an arbitrary noncompact n-dimensional Riemannian manifold with a boundary of conformally parabolic type it is proved that there exists a conformal change of metric such that a relative isoperimetric inequality of the same form as in the closed n-dimensional Euclidean half-space holds on the manifold with the new metric. This isoperimetric inequality is asymptotically sharp. Bibliography: 6 titles.

Kesel'man, Vladimir M [Moscow State Industrial University, Moscow (Russian Federation)

2011-07-31

441

On the dynamics of a degenerate parabolic equation: global bifurcation of stationary states and convergence  

Microsoft Academic Search

We study the dynamics of a degenerate parabolic equation with a variable, generally non-smooth diffusion coefficient, which\\u000a may vanish at some points or be unbounded. We show the existence of a global branch of nonnegative stationary states, covering\\u000a both the cases of a bounded and an unbounded domain. The global bifurcation of stationary states, implies-in conjuction with\\u000a the definition of

Nikos I. Karachalios; Nikos B. Zographopoulos

2006-01-01

442

X-ray parabolic collimator with depth-graded multilayer mirror  

Microsoft Academic Search

A very reliable and easily adjustable x-ray parabolic collimator with uniform intensity distribution in its output cross section is designed using the technology of depth-graded multilayer mirrors. The W\\/C multilayer mirror structure was specially designed so as to compensate for the decrease in output intensity at lower grazing angles. The advantages of depth-graded multilayer mirrors with respect to laterally graded

V. V. Protopopov; V. A. Shishkov; V. A. Kalnov

2000-01-01

443

Computationally efficient parabolic equation solutions to seismo-acoustic problems involving  

E-print Network

parabolic equation Assuming a time-harmonic source, the governing equations for a two-dimensional elas- tic medium, where x and z are range and depth coordinates in an axially symmetric cy- lindrical coordinate system, are9 ðk þ 2l? @2 u @x2 þ @ @z l @u @z þ qx2 u þ ðk þ l? @2 w @x@z þ @l @z @w @x ¼ 0; (1) l @2 w

444

Small Solar Power Systems /SSPS/  

NASA Astrophysics Data System (ADS)

A detailed description is given of the project organization, hardware, and projected performance of the distributed collector and central receiver solar thermal research facilities comprising the Small Power Systems (SSPS) plants in Almeria, Spain. The Distributed Collector System (DCS) is rated at 500 kWe and employs two fields of line-focusing parabolic trough collectors. The Central Receiver System (CRS) has the same rating and uses liquid sodium as a heat-transfer medium to circulate the 530 C heat yielded by a concentration factor of 450 from 4000 sq m of reflective surface. The purpose of the plant's dual configuration is the comparison of the two concentration methods under identical environmental conditions and the responsibility of a single operator/evaluator.

Grasse, W.

1981-05-01

445

Stability of W-Al 2O 3 cermet based solar coating for receiver tube operating at high temperature  

Microsoft Academic Search

An optimized solar multilayer coating based on W-Al2O3 graded cermet layer was fabricated in our laboratories by magnetron sputtering technique. To use this coating for the receiver tube of solar parabolic trough plants it is necessary for it to have very high structural, physical and chemical stability at high temperature (580C) under vacuum, maintaining good performances in terms of high

A. Antonaia; A. Castaldo; M. L. Addonizio; S. Esposito

2010-01-01

446

Numerical Study On Propulsion Performance Of The Parabolic Laser Thruster With Elongate Cylinder Nozzle  

NASA Astrophysics Data System (ADS)

Laser thrusters with a single nozzle, e.g. parabolic or conical, failed to constrict the flow field of high pressure effectively, resulting in poor propulsive performance. Under the condition of air-breathing mode, parabolic thruster models with an elongate cylinder nozzle were studied numerically by building a physical computation model. Initially, to verify the computation model, the influence of cylinder length on the momentum coupling coefficient was computed and compared with the experiments, which shows a good congruence. A model of diameter 20 mm and cylindrical length 80 mm obtains about 627.7 N/MW at single pulse energy density 1.5 J/cm2. Then, the influence of expanding angle of the parabolic nozzle on propulsion performance was gained for different laser pulse energies, and the evolution process of the flow field was analyzed. The results show: as the expanding angel increases, the momentum coupling coefficient increases remarkably at first and descends relative slowly after reaching a peak value; moreover, the peak positions stay constant around 33 with little variation when laser energy differs.

Cheng, Fuqiang; Hong, Yanji; Li, Qian; Wen, Ming

2011-11-01

447

The Effect of Boundary Support and Reflector Dimensions on Inflatable Parabolic Antenna Performance  

NASA Technical Reports Server (NTRS)

For parabolic antennas with sufficient surface accuracy, more power can be radiated with a larger aperture size. This paper explores the performance of antennas of various size and reflector depth. The particular focus is on a large inflatable elastic antenna reflector that is supported about its perimeter by a set of elastic tendons and is subjected to a constant hydrostatic pressure. The surface accuracy of the antenna is measured by an RMS calculation, while the reflector phase error component of the efficiency is determined by computing the power density at boresight. In the analysis, the calculation of antenna efficiency is not based on the Ruze Equation. Hence, no assumption regarding the distribution of the reflector surface distortions is presumed. The reflector surface is modeled as an isotropic elastic membrane using a linear stress-strain constitutive relation. Three types of antenna reflector construction are considered: one molded to an ideal parabolic form and two different flat panel design patterns. The flat panel surfaces are constructed by seaming together panels in a manner that the desired parabolic shape is approximately attained after pressurization. Numerical solutions of the model problem are calculated under a variety of conditions in order to estimate the accuracy and efficiency of these antenna systems. In the case of the flat panel constructions, several different cutting patterns are analyzed in order to determine an optimal cutting strategy.

Coleman, Michael J.; Baginski, Frank; Romanofsky, Robert R.

2011-01-01

448

Investigation of a Parabolic Iterative Solver for Three-dimensional Configurations  

NASA Technical Reports Server (NTRS)

A parabolic iterative solution procedure is investigated that seeks to extend the parabolic approximation used within the internal propagation module of the duct noise propagation and radiation code CDUCT-LaRC. The governing convected Helmholtz equation is split into a set of coupled equations governing propagation in the positive and negative directions. The proposed method utilizes an iterative procedure to solve the coupled equations in an attempt to account for possible reflections from internal bifurcations, impedance discontinuities, and duct terminations. A geometry consistent with the NASA Langley Curved Duct Test Rig is considered and the effects of acoustic treatment and non-anechoic termination are included. Two numerical implementations are studied and preliminary results indicate that improved accuracy in predicted amplitude and phase can be obtained for modes at a cut-off ratio of 1.7. Further predictions for modes at a cut-off ratio of 1.1 show improvement in predicted phase at the expense of increased amplitude error. Possible methods of improvement are suggested based on analytic and numerical analysis. It is hoped that coupling the parabolic iterative approach with less efficient, high fidelity finite element approaches will ultimately provide the capability to perform efficient, higher fidelity acoustic calculations within complex 3-D geometries for impedance eduction and noise propagation and radiation predictions.

Nark, Douglas M.; Watson, Willie R.; Mani, Ramani

2007-01-01

449

A parabolic model to control quantum interference in T-shaped molecular junctions.  

PubMed

Quantum interference (QI) effects in molecular devices have drawn increasing attention over the past years due to their unique features observed in the conductance spectrum. For the further development of single molecular devices exploiting QI effects, it is of great theoretical and practical interest to develop simple methods controlling the emergence and the positions of QI effects like anti-resonances or Fano line shapes in conductance spectra. In this work, starting from a well-known generic molecular junction with a side group (T-shaped molecule), we propose a simple graphical method to visualize the conditions for the appearance of quantum interference, Fano resonances or anti-resonances, in the conductance spectrum. By introducing a simple graphical representation (parabolic diagram), we can easily visualize the relation between the electronic parameters and the positions of normal resonant peaks and anti-resonant peaks induced by quantum interference in the conductance spectrum. This parabolic model not only can predict the emergence and energetic position of quantum interference from a few electronic parameters but also can enable one to know the coupling between the side group and the main conduction channel from measurements in the case of orthogonal basis. The results obtained within the parabolic model are validated using density-functional based quantum transport calculations in realistic T-shaped molecular junctions. PMID:23558406

Nozaki, Daijiro; Sevinli, Hldun; Avdoshenko, Stanislav M; Gutierrez, Rafael; Cuniberti, Gianaurelio

2013-09-01

450

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

451

Modeling Photovoltaic and Concentrating Solar Power Trough Performance, Cost, and Financing with the Solar Advisor Model: Preprint  

SciTech Connect

A comprehensive solar technology systems analysis model, the Solar Advisor Model (SAM), has been developed to support the federal R&D community and the solar industry by staff at the National Renewable Energy Laboratory (NREL) and Sandia National Laboratory. This model is able to model the finances, incentives, and performance of flat-plate photovoltaic (PV), concentrating PV, and concentrating solar power (specifically, parabolic troughs). The primary function of the model is to allow users to investigate the impact of variations in performance, cost, and financial parameters to better understand their impact on key figures of merit. Figures of merit related to the cost and performance of these systems include, but aren't limited to, system output, system efficiencies, levelized cost of energy, return on investment, and system capital and O&M costs. There are several models within SAM to model the performance of photovoltaic modules and inverters. This paper presents an overview of each PV and inverter model, introduces a new generic model, and briefly discusses the concentrating solar power (CSP) parabolic trough model. A comparison of results using the different PV and inverter models is also presented.

Blair, N.; Mehos, M.; Christensen, C.; Cameron, C.

2008-05-01

452

Infinite-dimensional backstepping for a class of parabolic distributed parameter systems  

NASA Astrophysics Data System (ADS)

The dissertation addresses the problem of feedback boundary control for parabolic Partial Differential Equations (PDEs). The main idea in our approach is to construct a nonsingular coordinate transformation, a special application of backstepping, that allows to convert the original system into a new set of coordinates where one can design a control law that stabilizes the system. We start with the example of an unstable heat equation. The stabilization is achieved by constructing a coordinate transformation that, if thought of as an integral transformation, has a feedback "kernel" that is a known continuous function. The limitation of the design with continuous kernel is that it cannot handle arbitrarily large level of the system instability. We then present two designs for nonlinear parabolic PDEs in 1D. The first design is for stabilization of a solid propellant rocket burning instability modeled by a single 1D PDE, while the second one is for the boundary control of chemical tubular reactors modeled by a system of two coupled 1D PDEs. The two designs are conceptually similar (the former one has a modification that handles a nonlinear destabilizing boundary condition imposed at the uncontrolled boundary) and guarantee stability for any finite discretization in space of the original PDE models. Using the experience from the design for the unstable heat equation, a modified approach with coordinate transformations that result in sufficiently regular kernels (not continuous but Linfinity) is developed for a class of linear parabolic PDEs motivated by engineering applications. The proposed design procedure can handle systems with an arbitrary finite number of open-loop unstable eigenvalues. We then extend the design for nonlinear ID parabolic PDE systems to 2D in a systematic fashion for a 2D thermal convection loop. We also explain how to obtain the coordinate transforms and how to apply control for systems in 3D. Finally, we show on the simulation examples for the heat convection loop, solid propellant rockets, and chemical tubular reactors that parabolic PDEs can be successfully stabilized for a variety of different simulation settings with low order backstepping controllers that use only a small number of state measurements.

Boskovic, Dejan M.

453

Integrated Solar Concentrator and Shielded Radiator  

NASA Technical Reports Server (NTRS)

A shielded radiator is integrated within a solar concentrator for applications that require protection from high ambient temperatures with little convective heat transfer. This innovation uses a reflective surface to deflect ambient thermal radiation, shielding the radiator. The interior of the shield is also reflective to provide a view factor to deep space. A key feature of the shield is the parabolic shape that focuses incoming solar radiation to a line above the radiator along the length of the trough. This keeps the solar energy from adding to the radiator load. By placing solar cells along this focal line, the concentration of solar energy reduces the number and mass of required cells. By shielding the radiator, the effective reject temperature is much lower, allowing lower radiator temperatures. This is particularly important for lower-temperature processes, like habitat heat rejection and fuel cell operations where a high radiator temperature is not feasible. Adding the solar cells in the focal line uses the concentrating effect of the shield to advantage to accomplish two processes with a single device. This shield can be a deployable, lightweight Mylar structure for compact transport.

Clark, David Larry

2010-01-01

454

Storage in residential solar total-energy systems  

NASA Astrophysics Data System (ADS)

The potential role of energy storage devices in solar total energy systems operating in a stand alone mode is examined. High temperature thermal storage is examined in the context of systems employing parabolic trough collectors and Rankine cycle conversion while batteries are evaluated in systems based on parabolic dish concentrators with Stirling cycle conversion or on nonconcentrating photovoltaic systems. In all three systems, storage was found to be advantageous in cases involving high future fuel prices and collectors meeting current cost goals, while storage was not found to be viable at fuel prices remaining near current levels and collector costs exceeding current expectations by substantial margins. Factors making storage more or less desirable are discussed. Throughout, analyses based on minimum cost (optimal) systems are employed.

Leigh, R. W.

1980-12-01

455

Solar Stirling power generation - Systems analysis and preliminary tests  

NASA Technical Reports Server (NTRS)

The feasibility of an electric power generation system utilizing a sun-tracking parabolic concentrator and a Stirling engine/linear alternator is being evaluated. Performance predictions and cost analysis of a proposed large distributed system are discussed. Design details and preliminary test results are presented for a 9.5 ft diameter parabolic dish at the Jet Propulsion Laboratory (Caltech) Table Mountain Test Facility. Low temperature calorimetric measurements were conducted to evaluate the concentrator performance, and a helium flow system is being used to test the solar receiver at anticipated working fluid temperatures (up to 650 or 1200 C) to evaluate the receiver thermal performance. The receiver body is designed to adapt to a free-piston Stirling engine which powers a linear alternator assembly for direct electric power generation. During the next phase of the program, experiments with an engine and receiver integrated into the concentrator assembly are planned.

Selcuk, M. K.; Wu, Y.-C.; Moynihan, P. I.; Day, F. D., III

1977-01-01

456

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

457

Prospects for the construction of solar furnaces for industry  

NASA Astrophysics Data System (ADS)

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 usage. It was found that the reliability of the furnace depends on the annual insolation, that the solar furnaces must be designed to meet specific thermal goals, that simplification and optimization are needed for the orientation and focusing mechanisms, and that solar furnaces are ideally suited for developing nations which experience high levels of insolation. A stepped paraboloid is described for improving the efficiency of a heliostat system, while still employing plane parallel mirrors.

La Blanchetais, Ch. H.

458

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.

459

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.

460

Solar energy  

NASA Astrophysics Data System (ADS)

The book opens with a review of the patterns of energy use and resources in the United States, and an exploration of the potential of solar energy to supply some of this energy in the future. This is followed by background material on solar geometry, solar intensities, flat plate collectors, and economics. Detailed attention is then given to a variety of solar units and systems, including domestic hot water systems, space heating systems, solar-assisted heat pumps, intermediate temperature collectors, space heating/cooling systems, concentrating collectors for high temperatures, storage systems, and solar total energy systems. Finally, rights to solar access are discussed.

Rapp, D.

461

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

462

United States Department of Energy solar receiver technology development  

NASA Astrophysics Data System (ADS)

The United States Department of Energy (DOE), through Sandia National Laboratories, has been conducting a Solar Thermal Receiver Technology Development Program, which maintains a balance between analytical modeling, bench and small scale testing, and experimentation conducted at scales representative of commercially-sized equipment. Central receiver activities emphasize molten salt-based systems on large scales and volumetric devices in the modeling and small scale testing. These receivers are expected to be utilized in solar power plants rated between 100 and 200 MW. Distributed receiver research focuses on liquid metal refluxing devices. These are intended to mate parabolic dish concentrators with Stirling cycle engines in the 5 to 25 kW(sub e) power range. The effort in the area of volumetric receivers is less intensive and highly cooperative in nature. A ceramic foam absorber of Sandia design was successfully tested on the 200 kW(sub t) test bed at Plataforma Solar during 1989. Material integrity during the approximately 90-test series was excellent. Significant progress has been made with parabolic dish concentrator-mounted receivers using liquid metals (sodium or a potassium/sodium mixture) as heat transport media. Sandia has successfully solar-tested a pool boiling reflux receiver sized to power a 25 kW Stirling engine. Boiling stability and transient operation were both excellent. This document describes these activities in detail and will outline plans for future development.

Klimas, P. C.; Diver, R. B.; Chavez, J. M.

463

Analysis of gene expression during parabolic flights reveals distinct early gravity responses in Arabidopsis roots.  

PubMed

Plant roots are among most intensively studied biological systems in gravity research. Altered gravity induces asymmetric cell growth leading to root bending. Differential distribution of the phytohormone auxin underlies root responses to gravity, being coordinated by auxin efflux transporters from the PIN family. The objective of this study was to compare early transcriptomic changes in roots of Arabidopsis thaliana wild type, and pin2 and pin3 mutants under parabolic flight conditions and to correlate these changes to auxin distribution. Parabolic flights allow comparison of transient 1-g, hypergravity and microgravity effects in living organisms in parallel. We found common and mutation-related genes differentially expressed in response to transient microgravity phases. Gene ontology analysis of common genes revealed lipid metabolism, response to stress factors and light categories as primarily involved in response to transient microgravity phases, suggesting that fundamental reorganisation of metabolic pathways functions upstream of a further signal mediating hormonal network. Gene expression changes in roots lacking the columella-located PIN3 were stronger than in those deprived of the epidermis and cortex cell-specific PIN2. Moreover, repetitive exposure to microgravity/hypergravity and gravity/hypergravity flight phases induced an up-regulation of auxin responsive genes in wild type and pin2 roots, but not in pin3 roots, suggesting a critical function of PIN3 in mediating auxin fluxes in response to transient microgravity phases. Our study provides important insights towards understanding signal transduction processes in transient microgravity conditions by combining for the first time the parabolic flight platform with the transcriptome analysis of different genetic mutants in the model plant, Arabidopsis. PMID:24373012

Aubry-Hivet, D; Nziengui, H; Rapp, K; Oliveira, O; Paponov, I A; Li, Y; Hauslage, J; Vagt, N; Braun, M; Ditengou, F A; Dovzhenko, A; Palme, K

2014-01-01

464

Reciprocal efficiency improvement of high temperature fossil and low temperature solar heat sources for power generation  

NASA Astrophysics Data System (ADS)

Gas turbine systems are investigated for solar energy conversion because they can offer satisfactory performances, particularly in case of combined cycles, and interesting solutions for plant operation. Hybrid concepts, associating solar heating with fossil firing, reduce the need for energy storage. Key problems are: matching of combined gas and steam cycles for performance enhancement, coupling of solar heating with fossil firing, use of as much solar energy as possible and priority use of solar energy at medium temperature (200/650 C), because, within this temperature range, technology is more readily available for the solar receiver system (central receiver, fixed mirror concentrators, parabolic dish collectors) and for the primary circuit (Gilotherm, Dowtherm, sodium, molten salts).

Tilliette, Z. P.; Pierre, B.

1980-03-01

465

Operation and performance of the Ciba-Corning 512 coagulation monitor during parabolic flight  

NASA Technical Reports Server (NTRS)

The goal was to assess the functionality and evaluate the procedures and operations required to operate the Ciba-Corning 512 Coagulation Monitor during parabolic flight. This monitor determines the clotting characteristics of blood. The analyzer operates by laser detection of the cessation of blood flow in a capillary channel within a test cartridge. Test simulator results were excellent for both pre-and post-flight. In-flight results were not obtained due to the warm-up time required for the simulator. Since this is an electronic function only, the expected results on the simulator would be the same in zero-g.

Gocke, Robyn; Lloyd, Charles W.; Greenthaner, Nancy K.

1991-01-01

466

A parametric study of error in the parabolic approximation of focused axisymmetric ultrasound beams.  

PubMed

The parabolic approximation results in a tractible model for studying ultrasound beams, but the limits of validity of the approximation are often presented only qualitatively. In this work the most common model for axisymmetric ultrasound beam propagation, the Kuznetsov-Zabolotskaya-Khokhlov equation, is directly compared with the more general Westervelt equation with regard to diffractive and absorptive effects in continuous wave beams. The parametric study compares the solutions of the two models as a function of source frequency and focusing geometry using peak focal pressure, the axial location at which that peak occurs, and the loss due to absorption as metrics. PMID:22713025

Soneson, Joshua E

2012-06-01

467

Visualization of Shock Wave Driven by Millimeter Wave Plasma in a Parabolic Thruster  

SciTech Connect

By focusing a high-power millimeter wave beam generated by a 170 GHz gyrotron, a breakdown occurred and a shock wave was driven by plasma heated by following microwave energy. The shock wave and the plasma around a focal point of a parabolic thruster were visualized by a shadowgraph method, and a transition of structures between the shock wave and the plasma was observed. There was a threshold local power density to make the transition, and the propagation velocity at the transition was around 800 m/s.

Yamaguchi, Toshikazu; Shimada, Yutaka; Shiraishi, Yuya; Shibata, Teppei; Komurasaki, Kimiya [Department of Advanced Energy, The University of Tokyo, 5-1-5 Kashiwa-no-ha, Kashiwa, Chiba, 277-8561 (Japan); Oda, Yasuhisa; Kajiwara, Ken; Takahashi, Koji; Kasugai, Atsushi; Sakamoto, Keishi [Plasma Heating Technology Group, Japan Atomic Energy Agency, 801-1 Mukoyama, Naka, Ibaraki, 311-0193 (Japan); Arakawa, Yoshihiro [Department of Aeronautics and Astronautics, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8656 (Japan)

2010-05-06

468

Parabolic inverse convection-diffusion-reaction problem solved using an adaptive parametrization  

E-print Network

This paper investigates the solution of a parabolic inverse problem based upon the convection-diffusion-reaction equation, which can be used to estimate both water and air pollution. We will consider both known and unknown source location: while in the first case the problem is solved using a projected damped Gauss-Newton, in the second one it is ill-posed and an adaptive parametrization with time localization will be adopted to regularize it. To solve the optimization loop a model reduction technique (Proper Orthogonal Decomposition) is used.

Deolmi, Giulia

2011-01-01

469

Voigt lineshape function as a solution of the parabolic partial differential equation  

NASA Astrophysics Data System (ADS)

The goal of this paper is to show that the Voigt function may be found as a solution of a parabolic partial differential equation, like the heat conduction equation or other diffusion equations. A square of the Gaussian half-width of the Voigt function plays the role of time and initial conditions are determined by a Lorentz function. Some questions concerning the practical application of the numerical grid methods for the calculation of the Voigt function are discussed. It is shown, that in some cases the offered calculation algorithm can be both faster and more accurate than other known algorithms.

Dulov, E. N.; Khripunov, D. M.

2007-10-01

470

3D mapping of intensity field about the focus of a micrometer scale parabolic mirror  

E-print Network

We report on the fabrication and diffraction-limited characterization of parabolic focusing micromirrors. Sub - micron beam waists are measured for mirrors with 10 {\\mu}m radius aperture and measured fixed focal lengths in the range from 24 {\\mu}m to 36 {\\mu}m. Optical characterization of the 3D intensity in the nearfield produced when the device is illuminated with collimated light is performed using a modified confocal microscope. Results are compared directly with angular spectrum simulations, yielding strong agreement between experiment and theory, and identifying the competition between diffraction and focusing in the regime probed.

McDonald, Alison; Cox, David C; Riis, Erling; Griffin, Paul F

2014-01-01

471

A higher-order split-step Fourier parabolic-equation sound propagation solution scheme.  

PubMed

A three-dimensional Cartesian parabolic-equation model with a higher-order approximation to the square-root Helmholtz operator is presented for simulating underwater sound propagation in ocean waveguides. The higher-order approximation includes cross terms with the free-space square-root Helmholtz operator and the medium phase speed anomaly. It can be implemented with a split-step Fourier algorithm to solve for sound pressure in the model. Two idealized ocean waveguide examples are presented to demonstrate the performance of this numerical technique. PMID:22894317

Lin, Ying-Tsong; Duda, Timothy F

2012-08-01

472

The Cauchy problem for a quasilinear parabolic equation with gradient absorption  

SciTech Connect

The qualitative properties of solutions to the Cauchy problem for a degenerate parabolic equation containing a nonlinear operator of Baouendi-Grushin type and with gradient absorption whose density depends on time, as well as the space variables, are investigated. Bounds for the diameter of the support of the solution which are sharp with respect to time are obtained, together with its maximum. A condition which determines whether or not the phenomenon of decay to zero of the total mass of the solution occurs is discovered. Bibliography: 35 titles.

Markasheva, Vera A; Tedeev, Anatoli F [Institute of Applied Mathematics and Mechanics, Ukraine National Academy of Sciences, Donetsk (Ukraine)

2012-04-30

473

Broadband seismo-acoustic modeling in range-dependent layered media using the parabolic equation method  

NASA Astrophysics Data System (ADS)

We present an efficient broadband modeling capability based on synthesizing solutions of the frequency-domain wave equation computed using the wide-angle parabolic equation (PE) method. The PE [a version of NRL's Range-dependent Acoustic Model (RAM)] takes into account recent advances for handling range-varying layer thicknesses, compression and shear waves, and surface/interfacial waves (Rayleigh, Stoneley). The technique allows for multiple sources on land, underground, or offshore. Long-range propagation examples demonstrating the computation of multiply reflected head waves are presented. Examples of using head waves and their related phenomena to perform geoacoustic inversion in multiple layers are shown.

Calvo, David C.; Collins, Michael D.

2005-09-01

474

Quantum damped oscillator II: Batemans Hamiltonian vs. 2D parabolic potential barrier  

NASA Astrophysics Data System (ADS)

We show that quantum Batemans 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.

Chru?ci?ski, Dariusz

2006-04-01

475

On the symmetry of the electronic density in the three-electron parabolic quantum dot  

E-print Network

The structure of the lowest states of a three-electron axially symmetric parabolic quantum dot in a zero magnetic field is investigated. It is shown that the electronic density of the triplet states possesses certain approximate symmetry which is best seen when using Dalitz plots as the visualization tool. It is demonstrated that the origin of that symmetry is caused by the symmetry of the potential energy in the vicinity of its minimum. The discovered symmetry could provide an insight into the problem of the separation of slow and fast variables in the Schro\\"dinger equation for the axially or spherically symmetric quantum dots.

Meremianin, A V

2014-01-01

476

Nearly Interactive Parabolized Navier-Stokes Solver for High Speed Forebody and Inlet Flows  

NASA Technical Reports Server (NTRS)

A system of computer programs is being developed for the preliminary design of high speed inlets and forebodies. The system comprises four functions: geometry definition, flow grid generation, flow solver, and graphics post-processor. The system runs on a dedicated personal computer using the Windows operating system and is controlled by graphical user interfaces written in MATLAB (The Mathworks, Inc.). The flow solver uses the Parabolized Navier-Stokes equations to compute millions of mesh points in several minutes. Sample two-dimensional and three-dimensional calculations are demonstrated in the paper.

Benson, Thomas J.; Liou, May-Fun; Jones, William H.; Trefny, Charles J.

2009-01-01

477

Structure and the Reflectionless/Refractionless Nature of Parabolic Diffusion-Wave Fields  

SciTech Connect

We show the impossibility of reflection and refraction phenomena at linear diffusion-wave-field (DWF) interfaces. Instead, interfacial flux expressions are derived which involve coherent accumulation or depletion phenomena subject to an interface flux conservation principle. The conditions for reflectionless and refractionless interfaces are the parabolic nature and the concomitant Fickian constitutive relations satisfied by DWFs. Simulations show that the reflection and Snell's laws can be adequate approximations only under near-normal incidence conditions, in agreement with published experimental evidence in wide areas of biomedical, electronic, and materials physics.

Mandelis, Andreas; Nicolaides, Lena; Chen, Yan

2001-07-09

478

Initial evolution of supports of solutions of quasilinear parabolic equations with degenerate absorption potential  

SciTech Connect

The propagation of supports of solutions of second-order quasilinear parabolic equations is studied; the equations are of the type of nonstationary diffusion, having semilinear absorption with an absorption potential which degenerates on the initial plane. We find sufficient conditions, which are sharp in a certain sense, on the relationship between the boundary regime and the type of degeneration of the potential to ensure the strong localization of solutions. We also establish a weak localization of solutions for an arbitrary potential which degenerates only on the initial plane. Bibliography: 12 titles.

Stepanova, Ekaterina V; Shishkov, Andrey E

2013-03-31

479

An Alternating Direction Implicit Scheme for Parabolic Equations with Mixed Derivative and Convective Terms  

NASA Astrophysics Data System (ADS)

An alternating direction implicit (ADI) scheme is introduced which is capable of solving a general parabolic equation in two space dimensions with mixed derivative and convective terms. In the case of constant coefficients the scheme is shown to be unconditionally stable. The study was motivated by the investigation of flow in a dye laser cell (a device used for the amplification of a laser beam), a simple model for which involves laminar flow in a two-dimensional symmetric channel subject to impulsive heating. Numerical results are presented for this problem, and the qualitative behaviour of the temperature distribution within the channel for different Peclet numbers is discussed.

McKee, S.; Wall, D. P.; Wilson, S. K.

1996-06-01

480

Research and development on a distributed type solar thermal power generation plant  

NASA Astrophysics Data System (ADS)

The R&D on a solar thermal power generation system of the plane parabolic type within the framework of the Japanese Sunshine Project is described. This system realizes high concentration of solar energy with a special concentrator module which combines 100 flat plate mirror heliostats of the central tower system with 5 parabolic troughs of the distributed system. A molten salt (KCl-LiCl) type thermal storage unit is used to superheat saturated steam supplied by accumulators to 300-350 C for 90 minutes after 5 hours of heat storage. Specifications and hydrodynamic characteristics for a 1000 kWe pilot plant in Nio, Kagawa, Japan, constructed in 1980 are given.

Sumida, I.; Tsukamoto, M.; Sakamoto, T.; Taki, T.; Sato, S.

1983-12-01

481

Solar thermionic power systems for terrestrial applications  

NASA Technical Reports Server (NTRS)

The results of a feasibility study which showed that a low-temperature, high-efficient thermionic power system can efficiently convert solar energy to electrical energy without heat transport, as required by most solar thermal systems are described. A 3-dimensional (2-axis tracking) 93 sq m parabolic solar concentrator, consisting of mirrors on a foam glass substrate and designed to a concentration ratio (mirror area/aperture area) of 2000 is considered for producing a design temperature of 1100 C at an efficiency of 74%. A tracking subsystem must track the sun at an accuracy of a nominal plus or minus 1.0 degree for maximum use of the sun's energy. Each complete solar thermionic power system unit rated at about 20 kWe peak can generate approximately 48,000 kWh/yr. In addition, a thermal energy conversion system can be cascaded within the thermionic power system so that the high quality waste heat can be further utilized to increase the net electrical output. Potential applications of a solar thermionic power generation system are remote sites, apartment house complexes, heating and cooling, hydrogen production and large power stations.

Shimada, K.; Swerdling, M.

1977-01-01

482

Galerkin Methods for Parabolic and SCHR{\\"O}DINGER Equations with Dynamical Boundary Conditions and Applications to Underwater Acoustics  

E-print Network

In this paper we consider Galerkin-finite element methods that approximate the solutions of initial-boundary-value problems in one space dimension for parabolic and Schr\\"odinger evolution equations with dynamical boundary conditions. Error estimates of optimal rates of convergence in $L^2$ and $H^1$ are proved for the accociated semidiscrete and fully discrete Crank-Nicolson-Galerkin approximations. The problem involving the Schr\\"odinger equation is motivated by considering the standard `parabolic' (paraxial) approximation to the Helmholtz equation, used in underwater acoustics to model long-range sound propagation in the sea, in the specific case of a domain with a rigid bottom of variable topography. This model is contrasted with alternative ones that avoid the dynamical bottom boundary condition and are shown to yield qualitatively better approximations. In the (real) parabolic case, numerical approximations are considered for dynamical boundary conditions of reactive and dissipative type.

Antonopoulou, D C; Zouraris, G E

2009-01-01

483

Algebraic and numerical analysis of imaging properties of thin tunable-focus fluidic membrane lenses with parabolic surfaces.  

PubMed

The theory of third-order aberrations for a system of rotationally symmetric thin tunable-focus fluidic membrane lenses with parabolic surfaces is described. A complex analysis of the third-order design of tunable fluidic lenses is performed considering all types of primary aberrations. Moreover, formulas are derived for the calculation of the change of aberration coefficients of the parabolic tunable fluidic membrane lens with respect to the wavelength. It is shown that spherical aberration of a simple tunable-focus fluidic membrane lens with parabolic surfaces can be corrected, which is not possible with a classical spherical lens. The presented analysis is explained on examples. Derived formulas make possible to calculate parameters of optical systems with fluidic membrane lenses with small residual aberrations. PMID:23545969

Miks, Antonin; Novak, Jiri; Novak, Pavel

2013-04-01

484

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

485

Performance testing of the Acurex solar collector model 3001-03  

NASA Astrophysics Data System (ADS)

Results are summarized of tests conducted at the Collector Module Test Facility on an Acurex Model 3001-03 Parabolic Trough Concentrating Solar Collector. Test temperature range was 100 C to 300 C. Tests were conducted with the collector axis oriented east-west and again with the collector axis oriented north-south. Three collectors were tested: one using polished aluminum mirrors, one using glass mirrors, and another using an aluminized acrylic film mirror.

Dudley, V. E.; Workhoven, R. M.

1982-03-01

486

Validated, unified model for optics and heat transfer in line-axis concentrating solar energy collectors  

Microsoft Academic Search

A rigorous numerical simulation model for the prediction of the combined optical and thermofluid behaviour of line-axis concentrating solar energy collectors combines two-dimensional steady-state finite element analysis of convective heat transfer and ray-trac