Investigation on the dynamic behaviour of a parabolic trough power plant during strongly cloudy days

International Nuclear Information System (INIS)

Al-Maliki, Wisam Abed Kattea; Alobaid, Falah; Starkloff, Ralf; Kez, Vitali; Epple, Bernd

2016-01-01

Highlights: • A detailed dynamic model of a parabolic trough solar thermal power plant is done. • Simulated results are compared to the experimental data from the real power plant. • Discrepancy between model result and real data is caused by operation strategy. • The model strategy increased the operating hours of power plant by around 2.5–3 h. - Abstract: The objective of this study is the development of a full scale dynamic model of a parabolic trough power plant with a thermal storage system, operated by the Actividades de Construcción y Servicios Group in Spain. The model includes solar field, thermal storage system and the power block and describes the heat transfer fluid and steam/water paths in detail. The parabolic trough power plant is modelled using Advanced Process Simulation Software (APROS). To validate the model, the numerical results are compared to the measured data, obtained from “Andasol II” during strongly cloudy periods in the summer days. The comparisons show a qualitative agreement between the dynamic simulation model and the measurements. The results confirm that the thermal storage enables the parabolic trough power plant to provide a constant power rate when the storage energy discharge is available, despite significant oscillations in the solar radiation.

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

Energy Technology Data Exchange (ETDEWEB)

Turchi, C. S.; Ma, Z.

2011-08-01

Parabolic trough power plants can provide reliable power by incorporating either thermal energy storage (TES) or backup heat from fossil fuels. This paper describes a gas turbine / parabolic trough hybrid design that combines a solar contribution greater than 50% with gas heat rates that rival those of natural gas combined-cycle plants. Previous work illustrated benefits of integrating gas turbines with conventional oil heat-transfer-fluid (HTF) troughs running at 390?C. This work extends that analysis to examine the integration of gas turbines with salt-HTF troughs running at 450 degrees C and including TES. Using gas turbine waste heat to supplement the TES system provides greater operating flexibility while enhancing the efficiency of gas utilization. The analysis indicates that the hybrid plant design produces solar-derived electricity and gas-derived electricity at lower cost than either system operating alone.

Slope Error Measurement Tool for Solar Parabolic Trough Collectors: Preprint

Energy Technology Data Exchange (ETDEWEB)

Stynes, J. K.; Ihas, B.

2012-04-01

The National Renewable Energy Laboratory (NREL) has developed an optical measurement tool for parabolic solar collectors that measures the combined errors due to absorber misalignment and reflector slope error. The combined absorber alignment and reflector slope errors are measured using a digital camera to photograph the reflected image of the absorber in the collector. Previous work using the image of the reflection of the absorber finds the reflector slope errors from the reflection of the absorber and an independent measurement of the absorber location. The accuracy of the reflector slope error measurement is thus dependent on the accuracy of the absorber location measurement. By measuring the combined reflector-absorber errors, the uncertainty in the absorber location measurement is eliminated. The related performance merit, the intercept factor, depends on the combined effects of the absorber alignment and reflector slope errors. Measuring the combined effect provides a simpler measurement and a more accurate input to the intercept factor estimate. The minimal equipment and setup required for this measurement technique make it ideal for field measurements.

Model and control scheme for recirculation mode direct steam generation parabolic trough solar power plants

International Nuclear Information System (INIS)

Guo, Su; Liu, Deyou; Chen, Xingying; Chu, Yinghao; Xu, Chang; Liu, Qunming; Zhou, Ling

2017-01-01

Highlights: •A nonlinear dynamic model of recirculation DSG parabolic trough is developed. •Collector row, water separator and spray attemperator are modeled, respectively. •The dynamic behaviors of the collector field are simulated and analyzed. •Transfer functions of water level and outlet fluid temperature are derived. •Multi-model switching generalized predictive control strategy is developed. -- Abstract: This work describes and evaluates a new nonlinear dynamic model, and a new generalized predictive control scheme for a collector field of direct steam generation parabolic troughs in recirculation mode. Modeling the dynamic behaviors of collector fields is essential to design, testing and validation of automatic control systems for direct steam generation parabolic troughs. However, the behaviors of two-phase heat transfer fluids impose challenges to simulating and developing process control schemes. In this work, a new nonlinear dynamic model is proposed, based on the nonlinear distributed parameter and the nonlinear lumped parameter methods. The proposed model is used to simulate and analyze the dynamic behaviors of the entire collector field for recirculation mode direct steam generation parabolic troughs under different weather conditions, without excessive computational costs. Based on the proposed model, transfer functions for both the water level of the separator and outlet steam temperatures are derived, and a new multi-model switching generalized predictive control scheme is developed for simulated control of the plant behaviors for a wide region of operational conditions. The proposed control scheme achieves excellent control performance and robustness for systems with long delay, large inertia and time-varying parameters, and efficiently solves the model mismatching problem in direct steam generation parabolic troughs. The performances of the model and control scheme are validated with design data from the project of Integration of Direct

Numerical simulation of solar parabolic trough collector performance in the Algeria Saharan region

International Nuclear Information System (INIS)

Marif, Yacine; Benmoussa, Hocine; Bouguettaia, Hamza; Belhadj, Mohamed M.; Zerrouki, Moussa

2014-01-01

Highlights: • The parabolic trough collector performance is examined. • The finite difference method is proposed and validated. • Two fluids are considered water and TherminolVP-1™. - Abstract: In order to determine the optical and thermal performance of a solar parabolic trough collector under the climate conditions of Algerian Sahara, a computer program based on one dimensional implicit finite difference method with energy balance approach has been developed. The absorber pipe, glass envelope and fluid were divided into several segments and the partial derivation in the differential equations was replaced by the backward finite difference terms in each segment. Two fluids were considered, liquid water and TherminolVP-1™ synthetic oil. Furthermore, the intensity of the direct solar radiation was estimated by monthly average values of the atmospheric Linke turbidity factor for different tracking systems. According to the simulation findings, the one axis polar East–West and horizontal East–West tracking systems were most desirable for a parabolic trough collector throughout the whole year. In addition, it is found that the thermal efficiency was about 69.73–72.24%, which decreases with the high synthetic oil fluid temperatures and increases in the lower water temperature by 2%

On purpose simulation model for molten salt CSP parabolic trough

Science.gov (United States)

Caranese, Carlo; Matino, Francesca; Maccari, Augusto

2017-06-01

The utilization of computer codes and simulation software is one of the fundamental aspects for the development of any kind of technology and, in particular, in CSP sector for researchers, energy institutions, EPC and others stakeholders. In that extent, several models for the simulation of CSP plant have been developed with different main objectives (dynamic simulation, productivity analysis, techno economic optimization, etc.), each of which has shown its own validity and suitability. Some of those models have been designed to study several plant configurations taking into account different CSP plant technologies (Parabolic trough, Linear Fresnel, Solar Tower or Dish) and different settings for the heat transfer fluid, the thermal storage systems and for the overall plant operating logic. Due to a lack of direct experience of Molten Salt Parabolic Trough (MSPT) commercial plant operation, most of the simulation tools do not foresee a suitable management of the thermal energy storage logic and of the solar field freeze protection system, but follow standard schemes. ASSALT, Ase Software for SALT csp plants, has been developed to improve MSPT plant's simulations, by exploiting the most correct operational strategies in order to provide more accurate technical and economical results. In particular, ASSALT applies MSPT specific control logics for the electric energy production and delivery strategy as well as the operation modes of the Solar Field in off-normal sunshine condition. With this approach, the estimated plant efficiency is increased and the electricity consumptions required for the plant operation and management is drastically reduced. Here we present a first comparative study on a real case 55 MWe Molten Salt Parabolic Trough CSP plant placed in the Tibetan highlands, using ASSALT and SAM (System Advisor Model), which is a commercially available simulation tool.

The cost of integration of parabolic trough CSP plants in isolated Mediterranean power systems

International Nuclear Information System (INIS)

Poullikkas, Andreas; Hadjipaschalis, Ioannis; Kourtis, George

2010-01-01

In this work, a technical and economic analysis concerning the integration of parabolic trough concentrated solar power (CSP) technologies, with or without thermal storage capability, in an existing typical small isolated Mediterranean power generation system, in the absence of a feed-in tariff scheme, is carried out. In addition to the business as usual (BAU) scenario, five more scenarios are examined in the analysis in order to assess the electricity unit cost with the penetration of parabolic trough CSP plants of 50 MWe or 100 MWe, with or without thermal storage capability. Based on the input data and assumptions made, the simulations indicated that the scenario with the utilization of a single parabolic trough CSP plant (either 50 MWe or 100 MWe and with or without thermal storage capability) in combination with BAU will effect an insignificant change in the electricity unit cost of the generation system compared to the BAU scenario. In addition, a sensitivity analysis on natural gas price, showed that increasing fuel prices and the existence of thermal storage capability in the CSP plant make this scenario marginally more economically attractive compared to the BAU scenario. (author)

Alignment method for parabolic trough solar concentrators

Science.gov (United States)

Diver, Richard B [Albuquerque, NM

2010-02-23

A Theoretical Overlay Photographic (TOP) alignment method uses the overlay of a theoretical projected image of a perfectly aligned concentrator on a photographic image of the concentrator to align the mirror facets of a parabolic trough solar concentrator. The alignment method is practical and straightforward, and inherently aligns the mirror facets to the receiver. When integrated with clinometer measurements for which gravity and mechanical drag effects have been accounted for and which are made in a manner and location consistent with the alignment method, all of the mirrors on a common drive can be aligned and optimized for any concentrator orientation.

Multi-parameter optimization design of parabolic trough solar receiver

International Nuclear Information System (INIS)

Guo, Jiangfeng; Huai, Xiulan

2016-01-01

Highlights: • The optimal condition can be obtained by multi-parameter optimization. • Exergy and thermal efficiencies are employed as objective function. • Exergy efficiency increases at the expense of heat losses. • The heat obtained by working fluid increases as thermal efficiency grows. - Abstract: The design parameters of parabolic trough solar receiver are interrelated and interact with one another, so the optimal performance of solar receiver cannot be obtained by the convectional single-parameter optimization. To overcome the shortcoming of single-parameter optimization, a multi-parameter optimization of parabolic trough solar receiver is employed based on genetic algorithm in the present work. When the thermal efficiency is taken as the objective function, the heat obtained by working fluid increases while the average temperature of working fluid and wall temperatures of solar receiver decrease. The average temperature of working fluid and the wall temperatures of solar receiver increase while the heat obtained by working fluid decreases generally by taking the exergy efficiency as an objective function. Assuming that the solar radiation intensity remains constant, the exergy obtained by working fluid increases by taking exergy efficiency as the objective function, which comes at the expense of heat losses of solar receiver.

Nonimaging compound parabolic concentrator-type reflectors with variable extreme direction.

Science.gov (United States)

Gordon, J M; Rabl, A

1992-12-01

The properties of nonimaging compound parabolic concentrator (CPC)-type devices are examined in which the extreme direction is not constant but rather is a variable that can change along the reflector. One can then retain the maximal concentration or radiative efficiency of the CPC while the flux map on the absorber or target is modified, depending on whether the device is used for optical concentration or for lighting. Two general classes of reflector are derived, and all the nonimaging devices developed to date are shown to be special cases of the general solution. These two classes are the nonimaging analog of converging and diverging devices of imaging optics.

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

Energy Technology Data Exchange (ETDEWEB)

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

2011-01-01

As deployment of parabolic trough concentrating solar power (CSP) systems ramps up, the need for reliable and robust performance acceptance test guidelines for the solar field is also amplified. Project owners and/or EPC contractors often require extensive solar field performance testing as part of the plant commissioning process in order to ensure that actual solar field performance satisfies both technical specifications and performance guaranties between the involved parties. Performance test code work is currently underway at the National Renewable Energy Laboratory (NREL) in collaboration with the SolarPACES Task-I activity, and within the ASME PTC-52 committee. One important aspect of acceptance testing is the selection of a robust technology performance model. NREL1 has developed a detailed parabolic trough performance model within the SAM software tool. This model is capable of predicting solar field, sub-system, and component performance. It has further been modified for this work to support calculation at subhourly time steps. This paper presents the methodology and results of a case study comparing actual performance data for a parabolic trough solar field to the predicted results using the modified SAM trough model. Due to data limitations, the methodology is applied to a single collector loop, though it applies to larger subfields and entire solar fields. Special consideration is provided for the model formulation, improvements to the model formulation based on comparison with the collected data, and uncertainty associated with the measured data. Additionally, this paper identifies modeling considerations that are of particular importance in the solar field acceptance testing process and uses the model to provide preliminary recommendations regarding acceptable steady-state testing conditions at the single-loop level.

A numerical analysis of the energy behavior of a parabolic trough ...

African Journals Online (AJOL)

The solar power is a clean and a durable energy; there are several techniques for using them. When necessary to elevated temperatures of heat transfer fluid, this energy must concentration. This paper presents the efficiencies study of a linear solar concentrator of a parabolic trough type. This study was conducted on the ...

Theoretical Study of the Compound Parabolic Trough Solar Collector

OpenAIRE

Dr. Subhi S. Mahammed; Dr. Hameed J. Khalaf; Tadahmun A. Yassen

2012-01-01

Theoretical design of compound parabolic trough solar collector (CPC) without tracking is presented in this work. The thermal efficiency is obtained by using FORTRAN 90 program. The thermal efficiency is between (60-67)% at mass flow rate between (0.02-0.03) kg/s at concentration ratio of (3.8) without need to tracking system.The total and diffused radiation is calculated for Tikrit city by using theoretical equations. Good agreement between present work and the previous work.

Parabolic trough solar concentrators: a technology which can contribute towards pakistan's energy future

International Nuclear Information System (INIS)

Masood, R.

2013-01-01

The utilization of solar thermal energy has got prime importance in Pakistan due to the current energy scarcity and escalating cost scenario in the country. Parabolic Trough Solar Concentrator is one of the most reliable technologies for utilization of solar thermal energy. In solar thermal power generation, Parabolic Trough Solar Concentrators are most successful as almost 96 percent of total solar thermal power is generated across the world by utilizing this technology. Its high reliability, operational compatibility, comparative low cost and high efficiency adds to its high value among other resources. Fortunately, Pakistan lies in the high Solar Insolation Zone; thus, a huge potential exists to benefit from this technology. This technology may cater to the Pakistan's seasonal increased electricity demand. Apart from electric power generation, this technology may also have cost-effective solutions for Pakistan's other industries, like steam generation, preheating of boiler make-up water, air-conditioning, and hot water production for food, textile, dairy and leather industries. However, economic justification of such projects would be possible only on accomplishing an indigenous technology base. Globally, this is a proven technology, but in Pakistan there is hardly any development in this field. In this study, an effort has been made by designing and fabricating an experimental Parabolic Trough Solar Water Heater by utilizing locally available materials and manufacturing capabilities. On achieving encouraging results, a solar boiler (steam generator) is proposed to be manufactured locally. (author)

Heat Loss Testing of Schott's 2008 PTR70 Parabolic Trough Receiver

Energy Technology Data Exchange (ETDEWEB)

Burkholder, Frank [National Renewable Energy Lab. (NREL), Golden, CO (United States); Kutscher, Chuck [National Renewable Energy Lab. (NREL), Golden, CO (United States)

2009-05-01

Two Schott 2008 model year PTR70 HCEs were tested on NREL's heat loss test stand from 100 - 500 deg C in 50 deg C increments. Absorber emittance was determined from the laboratory testing so that the performance of the HCEs could be modeled in a parabolic trough collector. Collector/HCE simulation results for many different field operation conditions were used to create heat loss correlationcoefficients for Excelergy and SAM. SAM estimates that the decreased emittance of the 2008 PTR70 will decrease the LCOE for parabolic trough power plants by 0.5 cents/kWh and increase the electricity generated by 5% relative to previous PTR70s. These conclusions assume that the 2008 PTR70 is supplied at the same cost and with the same optical performance as earlier PTR70 models.

Simulation of the parabolic trough solar energy generation system with Organic Rankine Cycle

International Nuclear Information System (INIS)

He, Ya-Ling; Mei, Dan-Hua; Tao, Wen-Quan; Yang, Wei-Wei; Liu, Huai-Liang

2012-01-01

Highlights: ► A parabolic trough solar power generation system with ORC is numerically simulated. ► The effects of key parameters on collector field and system performance are studied. ► Collector heat loss increases with small absorber and glass tube interlayer pressure. ► Heat collecting efficiency increases with initial increase of absorber HTO flow rate. ► Recommended thermal storage system volumes are different in year four typical days. -- Abstract: A model for a typical parabolic trough solar thermal power generation system with Organic Rankine Cycle (PT-SEGS–ORC) was built within the transient energy simulation package TRNSYS, which is formed by integrating several submodels for the trough collector system, the single-tank thermal storage system, the auxiliary power system and the heat-electricity conversion system. With this model, the effects of several key parameters, including the interlayer pressure between the absorber tube and the glass tube (p inter ), the flow rate of high temperature oil in the absorber tube (v), solar radiation intensity (I dn ) and incidence angle (θ), on the performance of the parabolic trough collector field based on the meteorological data of Xi’an city were examined. The study shows that the heat loss of the solar collector (q loss ) increases sharply with the increase in p inter at beginning and then reaches to an approximately constant value. The variation of heat collecting efficiency (η hc ) with v is quite similar to the variation of q loss with p inter . However, I dn and θ exhibit opposite effect on η hc . In addition, it is found that the optimal volume of the thermal storage system is sensitively dependent on the solar radiation intensity. The optimal volumes are 100, 150, 50, and 0 m 3 for spring equinox, summer solstice, autumnal equinox and winter solstice, respectively.

Theoretical Study of the Compound Parabolic Trough Solar Collector

Directory of Open Access Journals (Sweden)

Dr. Subhi S. Mahammed

2012-06-01

Full Text Available Theoretical design of compound parabolic trough solar collector (CPC without tracking is presented in this work. The thermal efficiency is obtained by using FORTRAN 90 program. The thermal efficiency is between (60-67% at mass flow rate between (0.02-0.03 kg/s at concentration ratio of (3.8 without need to tracking system.The total and diffused radiation is calculated for Tikrit city by using theoretical equations. Good agreement between present work and the previous work.

Annual measured and simulated thermal performance analysis of a hybrid solar district heating plant with flat plate collectors and parabolic trough collectors in series

DEFF Research Database (Denmark)

Tian, Zhiyong; Perers, Bengt; Furbo, Simon

2017-01-01

Flat plate collectors have relatively low efficiency at the typical supply temperatures of district heating networks (70–95 °C). Parabolic trough collectors retain their high efficiency at these temperatures. To maximize the advantages of flat plate collectors and parabolic trough collectors in l...... for this type of hybrid solar district heating plants with flat plate collectors and parabolic trough collectors in the Nordic region, but also introduce a novel design concept of solar district heating plants to other high solar radiation areas....... in large solar heating plants for a district heating network, a hybrid solar collector field with 5960 m2 flat plate collectors and 4039 m2 parabolic trough collectors in series was constructed in Taars, Denmark. The design principle is that the flat plate collectors preheat the return water from...

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

International Nuclear Information System (INIS)

Poullikkas, Andreas

2009-01-01

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 Government, including the relevant feed-in tariff. In order to identify the least cost feasible option for the installation of the parabolic trough solar thermal plant a parametric cost-benefit analysis is carried out by varying parameters, such as, parabolic trough solar thermal plant capacity, parabolic trough solar thermal capital investment, operating hours, carbon dioxide emission trading system price, etc. For all above cases the electricity unit cost or benefit before tax, as well as after tax cash flow, net present value, internal rate of return and payback period are calculated. The results indicate that under certain conditions such projects can be profitable. (author)

Performance and Simulation of a Stand-alone Parabolic Trough Solar Thermal Power Plant

Science.gov (United States)

Mohammad, S. T.; Al-Kayiem, H. H.; Assadi, M. K.; Gilani, S. I. U. H.; Khlief, A. K.

2018-05-01

In this paper, a Simulink® Thermolib Model has been established for simulation performance evaluation of Stand-alone Parabolic Trough Solar Thermal Power Plant in Universiti Teknologi PETRONAS, Malaysia. This paper proposes a design of 1.2 kW parabolic trough power plant. The model is capable to predict temperatures at any system outlet in the plant, as well as the power output produced. The conditions that are taken into account as input to the model are: local solar radiation and ambient temperatures, which have been measured during the year. Other parameters that have been input to the model are the collector’s sizes, location in terms of latitude and altitude. Lastly, the results are presented in graphical manner to describe the analysed variations of various outputs of the solar fields obtained, and help to predict the performance of the plant. The developed model allows an initial evaluation of the viability and technical feasibility of any similar solar thermal power plant.

A new desalination system using a combination of heat pipe, evacuated tube and parabolic trough collector

International Nuclear Information System (INIS)

Jafari Mosleh, H.; Jahangiri Mamouri, S.; Shafii, M.B.; Hakim Sima, A.

2015-01-01

Highlights: • A new desalination uses a combination of heat pipe and parabolic trough collector. • A twin-glass evacuated tube is used to decrease the thermal losses from heat pipe. • Adding oil into the space between heat pipe and tube collector enhances the yield. • The yield and efficiency reach up to 0.933 kg/(m 2 h) and 65.2%, respectively. - Abstract: The solar collectors have been commonly used in desalination systems. Recent investigations show that the use of a linear parabolic trough collector in solar stills can improve the efficiency of a desalination system. In this work, a combination of a heat pipe and a twin-glass evacuated tube collector is utilized with a parabolic trough collector. Results show that the rate of production and efficiency can reach to 0.27 kg/(m 2 h) and 22.1% when aluminum conducting foils are used in the space between the heat pipe and the twin-glass evacuated tube collector to transfer heat from the tube collector to the heat pipe. When oil is used as a medium for the transfer of heat, filling the space between heat pipe and twin-glass evacuated tube collector, the production and efficiency can increase to 0.933 kg/(m 2 h) and 65.2%, respectively

Full parabolic trough qualification from prototype to demonstration loop

Science.gov (United States)

Janotte, Nicole; Lüpfert, Eckhard; Pottler, Klaus; Schmitz, Mark

2017-06-01

On the example of the HelioTrough® collector development the full accompanying and supporting qualification program for large-scale parabolic trough collectors for solar thermal power plants is described from prototype to demonstration loop scale. In the evaluation process the actual state and the optimization potential are assessed. This includes the optical and geometrical performance determined by concentrator shape, deformation, assembly quality and local intercept factor values. Furthermore, its mechanical performance in terms of tracking accuracy and torsional stiffness and its thermal system performance on the basis of the overall thermal output and heat loss are evaluated. Demonstration loop tests deliver results of collector modules statistical slope deviation of 1.9 to 2.6 mrad, intercept factor above 98%, peak optical performance of 81.6% and heat loss coefficients from field tests. The benefit of such a closely monitored development lies in prompt feedback on strengths, weaknesses and potential improvements on the new product at any development stage from first module tests until demonstration loop evaluation. The product developer takes advantage of the achieved technical maturity, already before the implementation in a commercial power plant. The well-understood performance characteristics allow the reduction of safety margins making the new HelioTrough collector competitive from the start.

Parabolic Trough Solar Collector Initial Trials

Directory of Open Access Journals (Sweden)

Ghalya Pikra

2012-03-01

Full Text Available This paper discusses initial trials of parabolic trough solar collector (PTSC in Bandung. PTSC model consists of concentrator, absorber and tracking system. Concentrator designs are made with 2m aperture width, 6m length and 0.75m focal distance. The design is equipped with an automatic tracking system which is driven using 12V and 24Watt DC motor with 0.0125rpm rotational speed. Absorber/receiver is designed with evacuated tube type, with 1 inch core diameter and tube made of AISI304 and coated with black oxide, the outer tube is borosilicate glass with a 70 mm diameter and 1.5 m length. Working fluid stored in single type of thermal storage tank, a single phase with 37.7 liter volume. PTSC model testing carried out for 2 hours and 10 minutes produces heat output and input of 11.5 kW and 0.64 kW respectively. 

Thermodynamic analysis of a new design of temperature controlled parabolic trough collector

International Nuclear Information System (INIS)

Ceylan, İlhan; Ergun, Alper

2013-01-01

Highlights: • This new design parabolic trough collector has been made as temperature control. • The TCPTC system is very appropriate for the industrial systems which require high temperatures. • With TCPTC can provide hot water with low solar radiation. • TCPTC system costs are cheaper than other systems (thermo siphon systems, pomp systems, etc.). - Abstract: Numerous types of solar water heater are used throughout the world. These heaters can be classified into two groups as pumped systems and thermo siphon systems. However, water temperature cannot be controlled by these systems. In this study, a new temperature-controlled parabolic trough collector (TCPTC) was designed and analyzed experimentally. The analysis was made at a temperature range of 40–100 °C, with at intervals of 10 °C. A detailed analysis was performed by calculating energy efficiencies, exergy efficiencies, water temperatures and water amounts. The highest energy efficiency of TCPTC was calculated as 61.2 for 100 °C. As the set temperature increased, the energy efficiency increased as well. The highest exergy efficiency was calculated as 63 for 70 °C. However, as the set temperature increased, the exergy efficiency did not increase. Optimum exergy efficiency was obtained for 70 °C

A Novel Parabolic Trough Concentrating Solar Heating for Cut Tobacco Drying System

Directory of Open Access Journals (Sweden)

Jiang Tao Liu

2014-01-01

Full Text Available A novel parabolic trough concentrating solar heating for cut tobacco drying system was established. The opening width effect of V type metal cavity absorber was investigated. A cut tobacco drying mathematical model calculated by fourth-order Runge-Kutta numerical solution method was used to simulate the cut tobacco drying process. And finally the orthogonal test method was used to optimize the parameters of cut tobacco drying process. The result shows that the heating rate, acquisition factor, and collector system efficiency increase with increasing the opening width of the absorber. The simulation results are in good agreement with experimental data for cut tobacco drying process. The relative errors between simulated and experimental values are less than 8%, indicating that this mathematical model is accurate for the cut tobacco airflow drying process. The optimum preparation conditions are an inlet airflow velocity of 15 m/s, an initial cut tobacco moisture content of 26%, and an inlet airflow temperature of 200°C. The thermal efficiency of the dryer and the final cut tobacco moisture content are 66.32% and 14.15%, respectively. The result shows that this parabolic trough concentrating solar heating will be one of the heat recourse candidates for cut tobacco drying system.

Thermo-economic design optimization of parabolic trough solar plants for industrial process heat applications with memetic algorithms

International Nuclear Information System (INIS)

Silva, R.; Berenguel, M.; Pérez, M.; Fernández-Garcia, A.

2014-01-01

Highlights: • A thermo-economic optimization of a parabolic-trough solar plant for industrial process heat applications is developed. • An analysis of the influence of economic cost functions on optimal design point location is presented. • A multi-objective optimization approach to the design routine is proposed. • A sensitivity analysis of the optimal point location to economic, operational, and ambient conditions is developed. • Design optimization of a parabolic trough plant for a reference industrial application is developed. - Abstract: A thermo-economic design optimization of a parabolic trough solar plant for industrial processes with memetic algorithms is developed. The design domain variables considered in the optimization routine are the number of collectors in series, number of collector rows, row spacing, and storage volume. Life cycle savings, levelized cost of energy, and payback time objective functions are compared to study the influence on optimal design point location. Furthermore a multi-objective optimization approach is proposed to analyze the design problem from a multi-economic criteria point of view. An extensive set of optimization cases are performed to estimate the influence of fuel price trend, plant location, demand profile, operation conditions, solar field orientation, and radiation uncertainty on optimal design. The results allow quantifying as thermo-economic design optimization based on short term criteria as the payback time leads to smaller plants with higher solar field efficiencies and smaller solar fractions, while the consideration of optimization criteria based on long term performance of the plants, as life cycle savings based optimization, leads to the reverse conclusion. The role of plant location and future evolution of gas prices in the thermo-economic performance of the solar plant has been also analyzed. Thermo-economic optimization of a parabolic trough solar plant design for the reference industrial

Properties of solar generators with reflectors and radiators

Science.gov (United States)

Ebeling, W. D.; Rex, D.; Bierfischer, U.

1980-06-01

Radiation cooled concentrator systems using silicon and GaAs cells were studied. The principle of radiation cooling by the reflector surfaces is discussed for cylindrical parabolic reflectors (SARA), truncated hexagonal pyramids, and a small trough configuration. Beam paths, collection properties for imperfect orientation, and thermal optimization parameters were analyzed. The three concentrating systems with radiation cooling offer advantages over the plane panel and over the large trough. With silicon solar cells they exhibit considerably lower solar cell consumption per Kw and also lower mass per kW. With GaAs cells the SARA system reduces the number of solar cells needed per kW to less than 10%. Also in all other cases SARA offers the best values for alpha and F sub sol, as long as narrow angular tolerances of the panel orientation can be met. Analysis of the energy collecting properties for imperfect orientation shows the superiority of the hexagonal concentrator. This device can produce power for even large angles between the sun and the panel normal.

Survey mirrors and lenses and their required surface accuracy. Volume 2. Concentrator optical performance software (COPS) user's manual. Final report for September 15, 1978-December 1, 1979

Energy Technology Data Exchange (ETDEWEB)

1980-01-01

The mathematical modeling of 11 different concentrating collectors is documented and instructions are given for use of the computer code. The 11 concentrators modeled are: faceted mirror concentration; fixed mirror, two-axis tracking receiver; parabolic trough collector; linear Fresnel; incremental reflector; inflated cylindrical concentrator; CPC-involute reflector with evacuated receiver; CPC-parabolic/involute reflector; V trough collectors, imaging collapsing concentrator; and parabolic dish collector. (MHR)

Optical and thermal performance of large-size parabolic-trough solar collectors from outdoor experiments: A test method and a case study

International Nuclear Information System (INIS)

Valenzuela, Loreto; López-Martín, Rafael; Zarza, Eduardo

2014-01-01

This article presents an outdoor test method to evaluate the optical and thermal performance of parabolic-trough collectors of large size (length ≥ 100 m), similar to those currently installed in solar thermal power plants. Optical performance in line-focus collectors is defined by three parameters, peak-optical efficiency and longitudinal and transversal incidence angle modifiers. In parabolic-troughs, the transversal incidence angle modifier is usually assumed equal to 1, and the incidence angle modifier is referred to the longitudinal incidence angle modifier, which is a factor less than or equal to 1 and must be quantified. These measurements are performed by operating the collector at low fluid temperatures for reducing heat losses. Thermal performance is measured during tests at various operating temperatures, which are defined within the working temperature range of the solar field, and for the condition of maximum optical response. Heat losses are measured from both the experiments performed to measure the overall efficiency and the experiments done by operating the collector to ensure that absorber pipes are not exposed to concentrated solar radiation. The set of parameters describing the performance of a parabolic-trough collector of large size has been measured following the test procedures proposed and explained in the article. - Highlights: • Outdoor test procedures of parabolic-trough solar collector (PTC) of large size working at high temperature are described. • Optical performance measured with cold fluid temperature and thermal performance measured in the complete temperature range. • Experimental data obtained in the testing of a PTC prototype are explained

An air-based corrugated cavity-receiver for solar parabolic trough concentrators

International Nuclear Information System (INIS)

Bader, Roman; Pedretti, Andrea; Barbato, Maurizio; Steinfeld, Aldo

2015-01-01

Highlights: • We analyze a novel tubular cavity-receiver for solar parabolic trough collectors. • Four-fold solar concentration ratio is reached compared to conventional receivers. • Efficient operation at up to 500 °C is possible. • The pumping power requirement is found to be acceptably low. - Abstract: A tubular cavity-receiver that uses air as the heat transfer fluid is evaluated numerically using a validated heat transfer model. The receiver is designed for use on a large-span (9 m net concentrator aperture width) solar parabolic trough concentrator. Through the combination of a parabolic primary concentrator with a nonimaging secondary concentrator, the collector reaches a solar concentration ratio of 97.5. Four different receiver configurations are considered, with smooth or V-corrugated absorber tube and single- or double-glazed aperture window. The collector’s performance is characterized by its optical efficiency and heat loss. The optical efficiency is determined with the Monte Carlo ray-tracing method. Radiative heat exchange inside the receiver is calculated with the net radiation method. The 2D steady-state energy equation, which couples conductive, convective, and radiative heat transfer, is solved for the solid domains of the receiver cross-section, using finite-volume techniques. Simulations for Sevilla/Spain at the summer solstice at solar noon (direct normal solar irradiance: 847 W m −2 , solar incidence angle: 13.9°) yield collector efficiencies between 60% and 65% at a heat transfer fluid temperature of 125 °C and between 37% and 42% at 500 °C, depending on the receiver configuration. The optical losses amount to more than 30% of the incident solar radiation and constitute the largest source of energy loss. For a 200 m long collector module operated between 300 and 500 °C, the isentropic pumping power required to pump the HTF through the receiver is between 11 and 17 kW

Tracking local control of a parabolic trough collector. Control local de Seguimiento cilindro parabolico ACE 20

Energy Technology Data Exchange (ETDEWEB)

Ajona Maeztu, J.I.; Alberdi Primicia, J.; Gamero Aranda, E.; Blanco, J.

1991-01-01

In the local control, the sun position related to the trough collector is measured by two photo-resistors. the provided electronic signal is then compared with reference levels in order to get a set of 8 logical signals which form a byte. This byte and the commands issued by a programmable controller are connected to the inputs of a P.R.O.M. memory which is programmed with the logical ecuations of the control system. the memory output lines give the control commands of the parabolic trough collector motor. (author)

Tracking local control of a parabolic trough collector; Control local de Seguimiento cilindro parabolico ACE 20

Energy Technology Data Exchange (ETDEWEB)

Ajona Maeztu, J.I.; Alberdi Primicia, J.; Gamero Aranda, E.; Blanco, J.

1991-12-31

In the local control, the sun position related to the trough collector is measured by two photo-resistors. the provided electronic signal is then compared with reference levels in order to get a set of 8 logical signals which form a byte. This byte and the commands issued by a programmable controller are connected to the inputs of a P.R.O.M. memory which is programmed with the logical ecuations of the control system. the memory output lines give the control commands of the parabolic trough collector motor. (author)

Tracking local control of a parabolic trough collector; Control local de seguimiento cilindro parabolico ACE20

Energy Technology Data Exchange (ETDEWEB)

Ajona, J I; Alberdi, J; Gamero, E; Blanco, J

1992-07-01

In the local control, the sun position related to the trough collector is measured by two photo-resistors. The provided electronic signal is then compared with reference levels in order to get a set of B logical signals which form a byte. This byte and the commands issued by a programmable controller are connected to the inputs of o P.R.O.M. memory which is programmed with the logical equations of the control system. The memory output lines give the control command of the parabolic trough collector motor. (Author)

An experimental study of thermal characterization of parabolic trough receivers

International Nuclear Information System (INIS)

Lei, Dongqiang; Li, Qiang; Wang, Zhifeng; Li, Jian; Li, Jianbin

2013-01-01

Highlights: ► A new test stand of heat loss has been developed at IEECAS. ► A correlation between heat loss and absorber temperature is presented, 270 W/m 400 °C. ► The ratio of end loss in total heat loss increases with decreasing the temperature. ► The emittance test stand using a high vacuum system and vacuum gauge is built. ► Emittance first decreases, then rapidly increases with increasing the temperature. - Abstract: The receiver is a key component of the parabolic trough solar station. The receiver requires the most challenging technology and has a decisive influence on the thermal and economic performance of a power plant. The Institute of Electrical Engineering Chinese Academy Sciences (IEECAS) and Himin Solar Co., Ltd. (HSC) cooperated to develop solar receivers for the first 50 MW parabolic trough project in Inner Mongolia, China. This paper examines overall heat loss, end loss and thermal emittance of the coating of a newly designed receiver in order to evaluate its thermal characterization. A series of heat loss tests are conducted in a newly developed test stand following the steady state equilibrium method. The tests provide a correlation between heat loss and the absorber temperature. This paper presents a new testing method to accurately test the coating emittance. The method uses a receiver with a high vacuum system and a vacuum gauge to maintain continuous exhaust and high vacuum throughout the heat loss testing. A heat loss comparison between the receiver and other existing receivers provides a reference that enabled further optimization. Theoretical and experimental analysis examines the effects of end loss both with and without a heat insulator and a coil heater. The emittance curves of different coatings are acquired and the reasons for initial emittance decrease and then remarkable increase versus temperature are analyzed

Shaping of parabolic cylindrical membrane reflectors for the Dart Precision Test Bed

Science.gov (United States)

Morgan, R.; Agnes, Gregory S.; Dragovan, M.; Barber, D.; Marcin, M.; White, C.; Dooley, J.; Hatheway, A.

2004-01-01

The DART is a new telescope architecture consisting of a single aperture formed from two cylindrical parabolic reflectors. The system is ideally suited to using tensioned membranes for the reflective surfaces, owing to the zero Gaussian curvature of a cylindrical parabola. In this paper, we present experimental measurements for shaping the membranes by using curved boundary elements to achieve coarse shaping, and a pair of precision rails shaped by moments and forces at the ends, and lightly pushed into the surface, to provide fine shape control.

Design and experimental investigation of a stretched parabolic linear Fresnel reflector collecting system

International Nuclear Information System (INIS)

Zhu, Yanqing; Shi, Jifu; Li, Yujian; Wang, Leilei; Huang, Qizhang; Xu, Gang

2016-01-01

Highlights: • A parabolic primary mirror field is designed to reduce the gap between adjacent mirrors. • The movable receiver can reduce the end losses. • The thermal efficiency of 66% is achieved at Guangzhou in winter. - Abstract: This paper proposes a stretched parabolic linear Fresnel reflector (SPLFR) collecting system. The primary optical mirror field of the SPLFR collecting system and the second-stage concentrator of compound parabolic collector are designed. The mirrors located at the parabolic line are close to each other, which effectively reduce the gap between the adjacent mirrors. The end losses of the receiver are very important, especially in a small-scale collecting system. A movable receiver is introduced for the reduction of the end losses. Moreover, a stretched structure of SPLFR is designed for wind resistance. Finally, the thermal performance of the SPLFR collecting system with fixed and movable receiver located in Guangzhou is tested. The maximum thermal efficiency obtained by this collecting system with movable receiver is 66% which avoid the end losses effectively, and the solar collector thermal loss coefficient is 1.32 W/m"2 °C. The results show that the SPLFR collecting system has excellent thermal performance and a promising application future. Meanwhile, this system will provide a valuable reference for concentrating solar power technology.

Performance Evaluation of a Nanofluid-Based Direct Absorption Solar Collector with Parabolic Trough Concentrator

Directory of Open Access Journals (Sweden)

Guoying Xu

2015-12-01

Full Text Available Application of solar collectors for hot water supply, space heating, and cooling plays a significant role in reducing building energy consumption. For conventional solar collectors, solar radiation is absorbed by spectral selective coating on the collectors’ tube/plate wall. The poor durability of the coating can lead to an increased manufacturing cost and unreliability for a solar collector operated at a higher temperature. Therefore, a novel nanofluid-based direct absorption solar collector (NDASC employing uncoated collector tubes has been proposed, and its operating characteristics for medium-temperature solar collection were theoretically and experimentally studied in this paper. CuO/oil nanofluid was prepared and used as working fluid of the NDASC. The heat-transfer mechanism of the NDASC with parabolic trough concentrator was theoretically evaluated and compared with a conventional indirect absorption solar collector (IASC. The theoretical analysis results suggested that the fluid’s temperature distribution in the NDASC was much more uniform than that in the IASC, and an enhanced collection efficiency could be achieved for the NDASC operated within a preferred working temperature range. To demonstrate the feasibility of the proposed NDASC, experimental performances of an NDASC and an IASC with the same parabolic trough concentrator were furthermore evaluated and comparatively discussed.

Performance Evaluation of a Nanofluid-Based Direct Absorption Solar Collector with Parabolic Trough Concentrator

Science.gov (United States)

Xu, Guoying; Chen, Wei; Deng, Shiming; Zhang, Xiaosong; Zhao, Sainan

2015-01-01

Application of solar collectors for hot water supply, space heating, and cooling plays a significant role in reducing building energy consumption. For conventional solar collectors, solar radiation is absorbed by spectral selective coating on the collectors’ tube/plate wall. The poor durability of the coating can lead to an increased manufacturing cost and unreliability for a solar collector operated at a higher temperature. Therefore, a novel nanofluid-based direct absorption solar collector (NDASC) employing uncoated collector tubes has been proposed, and its operating characteristics for medium-temperature solar collection were theoretically and experimentally studied in this paper. CuO/oil nanofluid was prepared and used as working fluid of the NDASC. The heat-transfer mechanism of the NDASC with parabolic trough concentrator was theoretically evaluated and compared with a conventional indirect absorption solar collector (IASC). The theoretical analysis results suggested that the fluid’s temperature distribution in the NDASC was much more uniform than that in the IASC, and an enhanced collection efficiency could be achieved for the NDASC operated within a preferred working temperature range. To demonstrate the feasibility of the proposed NDASC, experimental performances of an NDASC and an IASC with the same parabolic trough concentrator were furthermore evaluated and comparatively discussed. PMID:28347112

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

Energy Technology Data Exchange (ETDEWEB)

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

2010-12-01

The National Renewable Energy Laboratory (NREL) contracted with WorleyParsons Group, Inc. to examine the effect of switching from evaporative cooling to alternative cooling systems on a nominal 100-MW parabolic trough concentrating solar power (CSP) plant. WorleyParsons analyzed 13 different cases spanning three different geographic locations (Daggett, California; Las Vegas, Nevada; and Alamosa, Colorado) to assess the performance, cost, and water use impacts of switching from wet to dry or hybrid cooling systems. NREL developed matching cases in its Solar Advisor Model (SAM) for each scenario to allow for hourly modeling and provide a comparison to the WorleyParsons results.Our findings indicate that switching from 100% wet to 100% dry cooling will result in levelized cost of electricity (LCOE) increases of approximately 3% to 8% for parabolic trough plants throughout most of the southwestern United States. In cooler, high-altitude areas like Colorado's San Luis Valley, WorleyParsons estimated the increase at only 2.5%, while SAM predicted a 4.4% difference. In all cases, the transition to dry cooling will reduce water consumption by over 90%. Utility time-of-delivery (TOD) schedules had similar impacts for wet- and dry-cooled plants, suggesting that TOD schedules have a relatively minor effect on the dry-cooling penalty.

Performance study on evacuated tube solar collector using therminol D-12 as heat transfer fluid coupled with parabolic trough

International Nuclear Information System (INIS)

Selvakumar, P.; Somasundaram, P.; Thangavel, P.

2014-01-01

Highlights: • Instant hot water at temperatures between 40 °C and 68 °C in the low solar radiation range of 240–540 W/m 2 . • Usage of therminol D-12 and parabolic trough in low temperature application. • Stability of thermal and flow properties of therminol D-12 are studied. - Abstract: Fossil fuels and electrical energy are widely used for instant hot water generation in rural and urban areas. Also, conventional solar water heaters do not support instant hot water generation because of various problems. A new system with evacuated tube collector using synthetic oil as heat transfer fluid coupled with parabolic trough is developed and studied experimentally for instant hot water generation in the presence of low solar irradiance. Among the different grades of therminol, therminol D-12 is chosen for the study because of its thermal stability. Parabolic trough is coupled to evacuated tube to enhance the flow as well as heating characteristics of therminol. Heating efficiency and temperature characteristics are determined for the newly developed system under low solar irradiance conditions. Instant hot water can be produced by the new system at a temperature of 60 °C in the presence of low solar radiation. This newly developed system has the ability to check the fossil fuel consumption and electrical energy consumption for instant hot water generation in household applications. The stability of the heat transfer fluid is also ensured by repeated experiments

A point focusing double parabolic trough concentrator

Energy Technology Data Exchange (ETDEWEB)

Murphree, Quincy C. [Kentucky Mountain Bible College, Vancleve, KY (United States)

2001-07-01

This article shows that a point focusing solar concentrator can be made from two reflective parabolic troughs, a primary and a secondary, by orienting their longitudinal axes in perpendicular directions and separating them by the difference of their focal lengths along the optical axis. This offers a new alternative to the conventional 3-D paraboloidal concentrator permitting more flexibility in designs for applications requiring high concentrations. Both advantages and disadvantages are discussed. The intensity concentration ratio distribution is calculated in the focal plane and has elliptically shaped contours due to the inherent compensation of errant rays by the concave secondary. The ratio of the major to minor axes was 2.61 for the case considered, resulting in a concentration {approx}2.61 times that of a comparable concentrator without the compensation afforded by a concave secondary. Still, geometrical constraints limit the concentration to about 2000 suns for mirror quality errors of 5 mr. Optimisation of the compensation effect holds potential for improved performance for other concentrator designs. Finally, the functional dependence of the peak concentration and shading factor upon design parameters are presented. (Author)

Survey of Thermal Storage for Parabolic Trough Power Plants; Period of Performance: September 13, 1999 - June 12, 2000

Energy Technology Data Exchange (ETDEWEB)

Pilkington Solar International GmbH

2000-09-29

The purpose of this report is to identify and selectively review previous work done on the evaluation and use of thermal energy storage systems applied to parabolic trough power plants. Appropriate storage concepts and technical options are first discussed, followed by a review of previous work.

Air-borne shape measurement of parabolic trough collector fields

Science.gov (United States)

Prahl, Christoph; Röger, Marc; Hilgert, Christoph

2017-06-01

The optical and thermal efficiency of parabolic trough collector solar fields is dependent on the performance and assembly accuracy of its components such as the concentrator and absorber. For the purpose of optical inspection/approval, yield analysis, localization of low performing areas, and optimization of the solar field, it is essential to create a complete view of the optical properties of the field. Existing optical measurement tools are based on ground based cameras, facing restriction concerning speed, volume and automation. QFly is an airborne qualification system which provides holistic and accurate information on geometrical, optical, and thermal properties of the entire solar field. It consists of an unmanned aerial vehicle, cameras and related software for flight path planning, data acquisition and evaluation. This article presents recent advances of the QFly measurement system and proposes a methodology on holistic qualification of the complete solar field with minimum impact on plant operation.

A review of Andasol 3 and perspective for parabolic trough CSP plants in South Africa

Science.gov (United States)

Dinter, Frank; Möller, Lucas

2016-05-01

Andasol 3 is a 50 MW parabolic trough concentrating solar power plant with thermal energy storage in Andalusia, southern Spain. Having started operating in 2011 as one of the first plants of its kind in Spain it has been followed by more than 50 in the country since. For the reason that CSP plants with storage have the potential to compete against fossil fuel fired plants much better than any other renewable energy source a long-term review of such a plant operating on a commercial scale is needed. With data at hand documenting Andasol 3's operation over the course of one year between July 2013 and June 2014 we intend to provide such a review. We calculated the plants overall efficiency, its capacity factor, the gross energy generation as well as auxiliary powers on a monthly basis to reflect upon its overall performance. It was also looked at the benefits caused by the thermal energy storage and especially how steadily and reliably the plant was able to operate. With basic background information about physical, geographical and meteorological aspects influencing the solar resource, its variation and a CSP plant's performance a qualitative estimation for a parabolic trough plant located in South Africa was made.

Thermodynamic optimisation of the performance of a parabolic trough receiver using synthetic oil–Al2O3 nanofluid

International Nuclear Information System (INIS)

Mwesigye, Aggrey; Huan, Zhongjie; Meyer, Josua P.

2015-01-01

Highlights: • Thermodynamic analysis of a parabolic trough receiver with nanofluids is presented. • Syltherm800–Al 2 O 3 nanofluid is used as the heat transfer fluid in the receiver. • Influence of nanoparticle volume fraction on receiver performance is investigated. • There is an optimal Reynolds number at each temperature and volume fraction. • Receiver thermal and thermodynamic performance improves below some Reynolds number. - Abstract: In this paper, results of a thermodynamic analysis using the entropy generation minimisation method for a parabolic trough receiver tube making use of a synthetic oil–Al 2 O 3 nanofluid as a heat transfer fluid are presented. A parabolic trough collector system with a rim angle of 80° and a concentration ratio of 86 was used. The temperature of the nanofluid considered was in the range of 350–600 K. The nanofluid thermal physical properties are temperature dependent. The Reynolds number varies from 3,560 to 1,151,000, depending on the temperature considered and volume fraction of nanoparticles in the base fluid. Nanoparticle volume fractions in the range 0 ⩽ ϕ ⩽ 8% were used. The local entropy generation rates due to fluid flow and heat transfer were determined numerically and used for the thermodynamic analysis. The study shows that using nanofluids improves the thermal efficiency of the receiver by up to 7.6%. There is an optimal Reynolds number at each inlet temperature and volume fraction for which the entropy generated is a minimum. The optimal Reynolds number decreases as the volume fraction increases. There is also a Reynolds number at every inlet temperature and volume fraction beyond which use of nanofluids is thermodynamically undesirable

Control concepts for direct steam generation in parabolic troughs

Energy Technology Data Exchange (ETDEWEB)

Valenzuela, Loreto; Zarza, Eduardo [CIEMAT, Plataforma Solar de Almeria, Tabernas (Almeria) (Spain); Berenguel, Manuel [Universidad de Almeria, Dept. de Lenguajes y Computacion, Almeria (Spain); Camacho, Eduardo F. [Universidad de Sevilla, Dept. de Ingenieria de Sistemas y Automatica, Sevilla (Spain)

2005-02-01

A new prototype parabolic-trough collector system was erected at the Plataforma Solar de Almeria (PSA) (1996-1998) to investigate direct steam generation (DSG) in a solar thermal power plant under real solar conditions. The system has been under evaluation for efficiency, cost, control and other parameters since 1999. The main objective of the control system is to obtain steam at constant temperature and pressure at the solar field outlet, so that changes in inlet water conditions and/or in solar radiation affect the amount of steam, but not its quality or the nominal plant efficiency. This paper presents control schemes designed and tested for two operating modes, 'Recirculation', for which a proportional-integral-derivative (PI/PID) control functions scheme has been implemented, and 'Once-through', requiring more complex control strategies, for which the scheme is based on proportional-integral (PI), feedforward and cascade control. Experimental results of both operation modes are discussed. (Author)

Impact of pressure losses in small-sized parabolic-trough collectors for direct steam generation

International Nuclear Information System (INIS)

Lobón, David H.; Valenzuela, Loreto

2013-01-01

Using PTC (parabolic-trough solar collectors) for industrial thermal processes in the temperature range up to 300 °C is not new, but in recent years there is a boosted interest in this type of concentrating solar technology. One of the problems that arise when designing PTC solar fields is how to deal with the pressure losses which are critical when producing saturated steam directly in the collectors. Depending on the characteristics of the collector, mainly on the receiver diameter, and on the nominal process conditions defined, a solar field configuration can be feasible or not. This paper presents a sensitivity analysis done using a software tool developed to study the thermo-hydraulic behaviour of PTC systems using water-steam as heat transfer fluid. In the case study presented, a small-sized PTC designed for industrial process heat applications is considered, which has a focal length of 0.2 m, an aperture area of 2 m 2 , and its receiver pipe has an inner diameter of 15 mm. Varied process conditions are inlet water pressure, temperature, and mass flow rate, solar irradiance and incidence angle of solar radiation. Results show that working pressure definition is particularly critical to make feasible or not the direct steam generation in solar collectors. - Highlights: • DSG (Direct steam generation) in small-sized parabolic-trough collectors. • Thermo-hydraulic sensitivity analysis. • Influence of working pressure and receiver geometry in DSG process

Theoretical investigation of solar humidification-dehumidification desalination system using parabolic trough concentrators

International Nuclear Information System (INIS)

Mohamed, A.M.I.; El-Minshawy, N.A.

2011-01-01

Highlights: → We evaluated the performance of sea water HDD system powered by solar PTC. → The proposed design to the expected desalination plant performance was introduced. → The collector thermal efficiency was a function of solar radiation value. → The highest fresh water productivity is found to be in the summer season. → The production time reaches 42% of the day time in the summer season. - Abstract: This paper deals with the status of solar energy as a clean and renewable energy applications in desalination. The object of this research is to theoretically investigate the principal operating parameters of a proposed desalination system based on air humidification-dehumidification principles. A parabolic trough solar collector is adapted to drive and optimize the considered desalination system. A test set-up of the desalination system was designed and a theoretical simulation model was constructed to evaluate the performance and productivity of the proposed solar humidification-dehumidification desalination system. The theoretical simulation model was developed in which the thermodynamic models of each component of the considered were set up respectively. The study showed that, parabolic trough solar collector is the suitable to drive the proposed desalination system. A comparison study had been presented to show the effect of the different parameters on the performance and the productivity of the system. The productivity of the proposed system showed also an increase with the increase of the day time till an optimum value and then decreased. The highest fresh water productivity is found to be in the summer season, when high direct solar radiation and long solar time are always expected. The production time reaches a maximum value in the summer season, which is 42% of the day.

Object-oriented simulation model of a parabolic trough solar collector: Static and dynamic validation

Science.gov (United States)

Ubieta, Eduardo; Hoyo, Itzal del; Valenzuela, Loreto; Lopez-Martín, Rafael; Peña, Víctor de la; López, Susana

2017-06-01

A simulation model of a parabolic-trough solar collector developed in Modelica® language is calibrated and validated. The calibration is performed in order to approximate the behavior of the solar collector model to a real one due to the uncertainty in some of the system parameters, i.e. measured data is used during the calibration process. Afterwards, the validation of this calibrated model is done. During the validation, the results obtained from the model are compared to the ones obtained during real operation in a collector from the Plataforma Solar de Almeria (PSA).

Oceanic Sub-Moho Reflectors in and Around the Segmentation Boundary Between the Tonankai-Nankai Earthquake Area, the Central Nankai Trough

Science.gov (United States)

Nakanishi, A.; Kodaira, S.; Miura, S.; Ito, A.; Sato, T.; Park, J.; Obana, K.; Kaneda, Y.

2006-12-01

The Nankai Trough is a unique subduction zone because the recurrence intervals of M8 class earthquakes and the segmentation of rupture zones are well documented on the basis of geophysical, geological and historic data. In 2004, large intraslab earthquake (Mw7.5) occurred southeast off the Kii Peninsula, the central Nankai Trough. Recent ocean bottom seismograph observation off the Kii Peninsula shows seismicity concentrated in the oceanic crust and the uppermost mantle. To understand the genesis of such intraslab earthquakes and its relation to large interplate earthquakes as well as to obtain an entire structural image of Nankai Trough subduction seismogenic zone, a wide-angle reflection/refraction survey across the coseismic rupture zone of the Tonankai earthquake was conducted in 2004. This research is part of "Structure research on plate dynamics of the presumed rupture zone of the Tonankai-Nankai Earthquakes" funded by Ministry of Education, Culture, Sports, Science and Technology. The result of structural image shows a bit thicker oceanic crust (>8km) subducting landward, and the existence of oceanic sub-Moho reflectors in the uppermost mantle. The aftershocks of the 2004 off Kii Peninsula earthquake are distributed within the oceanic crust and the uppermantle, which is not consistent with the estimated fault plane of main shock. Comparing the structural image with this aftershock distribution and usual seismicity in the uppermost mantle, the depth of the oceanic sub-Moho reflectors and the intraslab events within the uppermantle are both distributed around 20km. We consider that such sub-Moho reflectors may become a seismic fault of intraslab earthquakes.

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

Energy Technology Data Exchange (ETDEWEB)

Grogan, Dylan C. P.

2013-08-15

Executive Summary This Final Report for the "Development of Molten-Salt Heat Transfer Fluid (HTF) Technology for Parabolic Trough Solar Power Plants” describes the overall project accomplishments, results and conclusions. Phase 1 analyzed the feasibility, cost and performance of a parabolic trough solar power plant with a molten salt heat transfer fluid (HTF); researched and/or developed feasible component options, detailed cost estimates and workable operating procedures; and developed hourly performance models. As a result, a molten salt plant with 6 hours of storage was shown to reduce Thermal Energy Storage (TES) cost by 43.2%, solar field cost by 14.8%, and levelized cost of energy (LCOE) by 9.8% - 14.5% relative to a similar state-of-the-art baseline plant. The LCOE savings range met the project’s Go/No Go criteria of 10% LCOE reduction. Another primary focus of Phase 1 and 2 was risk mitigation. The large risk areas associated with a molten salt parabolic trough plant were addressed in both Phases, such as; HTF freeze prevention and recovery, collector components and piping connections, and complex component interactions. Phase 2 analyzed in more detail the technical and economic feasibility of a 140 MWe,gross molten-salt CSP plant with 6 hours of TES. Phase 2 accomplishments included developing technical solutions to the above mentioned risk areas, such as freeze protection/recovery, corrosion effects of applicable molten salts, collector design improvements for molten salt, and developing plant operating strategies for maximized plant performance and freeze risk mitigation. Phase 2 accomplishments also included developing and thoroughly analyzing a molten salt, Parabolic Trough power plant performance model, in order to achieve the project cost and performance targets. The plant performance model and an extensive basic Engineering, Procurement, and Construction (EPC) quote were used to calculate a real levelized cost of energy (LCOE) of 11.50�

Control scheme for direct steam generation in parabolic troughs under recirculation operation mode

Energy Technology Data Exchange (ETDEWEB)

Valenzuela, L.; Zarza, E. [CIEMAT, Plataforma Solar de Almeria, Ctra. Senes s/n, P.O. Box 22, E-04200 Tabernas, Almeria (Spain); Berenguel, M. [Universidad de Almeria, Dpto. Lenguajes y Computacion, Ctra. Sacramento s/n, E-04120 Almeria (Spain); Camacho, E.F. [Universidad de Sevilla, Dpto. de Ingenieria de Sistemas y Automatica, Camino de los Descubrimientos s/n, E-41092 Sevilla (Spain)

2006-01-15

Electricity production using solar thermal energy is one of the main research areas at present in the field of renewable energies, these systems being characterised by the need of reliable control systems aimed at maintaining desired operating conditions in the face of changes in solar radiation, which is the main source of energy. A new prototype of solar system with parabolic trough collectors was implemented at the Plataforma Solar de Almeria (PSA, South-East Spain) to investigate the direct steam generation process under real solar conditions in the parabolic solar collector field of a thermal power plant prototype. This paper presents details and some results of the application of a control scheme designed and tested for the recirculation operation mode, for which the main objective is to obtain steam at constant temperature and pressure at the outlet of the solar field, so that changes produced in the inlet water conditions and/or solar radiation will only affect the amount of steam produced by the solar field. The steam quality and consequently the nominal efficiency of the plant are thus maintained. (author)

Norwich Technologies' Advanced Low-Cost Receivers for Parabolic Troughs

Energy Technology Data Exchange (ETDEWEB)

Stettenheim, Joel [Norwich Technologies, White River Junction, VT (United States); McBride, Troy O. [Norwich Technologies, White River Junction, VT (United States); Brambles, Oliver J. [Norwich Technologies, White River Junction, VT (United States); Cashin, Emil A. [Norwich Technologies, White River Junction, VT (United States)

2013-12-31

This report summarizes the successful results of our SunShot project, Advanced Low-Cost Receivers for Parabolic Troughs. With a limited budget of $252K and in only 12 months, we have (1) developed validated optical and thermal models and completed rigorous optimization analysis to identify key performance characteristics as part of developing first-generation laboratory prototype designs, (2) built optical and thermal laboratory prototypes and test systems with associated innovative testing protocols, and (3) performed extensive statistically relevant testing. We have produced fully functioning optical and thermal prototypes and accurate, validated models shown to capture important underlying physical mechanisms. The test results from the first-generation prototype establish performance exceeding the FOA requirement of thermal efficiency >90% for a CSP receiver while delivering an exit fluid temperature of > 650 °C and a cost < $150/kWth. Our vacuum-free SunTrap receiver design provides improvements over conventional vacuum-tube collectors, allowing dramatic reductions in thermal losses at high operating temperature.

Sensitivity analysis on the effect of key parameters on the performance of parabolic trough solar collectors

Science.gov (United States)

Muhlen, Luis S. W.; Najafi, Behzad; Rinaldi, Fabio; Marchesi, Renzo

2014-04-01

Solar troughs are amongst the most commonly used technologies for collecting solar thermal energy and any attempt to increase the performance of these systems is welcomed. In the present study a parabolic solar trough is simulated using a one dimensional finite element model in which the energy balances for the fluid, the absorber and the envelope in each element are performed. The developed model is then validated using the available experimental data . A sensitivity analysis is performed in the next step in order to study the effect of changing the type of the working fluid and the corresponding Reynolds number on the overall performance of the system. The potential improvement due to the addition of a shield on the upper half of the annulus and enhancing the convection coefficient of the heat transfer fluid is also studied.

Sensitivity analysis on the effect of key parameters on the performance of parabolic trough solar collectors

International Nuclear Information System (INIS)

Muhlen, Luis S W; Najafi, Behzad; Rinaldi, Fabio; Marchesi, Renzo

2014-01-01

Solar troughs are amongst the most commonly used technologies for collecting solar thermal energy and any attempt to increase the performance of these systems is welcomed. In the present study a parabolic solar trough is simulated using a one dimensional finite element model in which the energy balances for the fluid, the absorber and the envelope in each element are performed. The developed model is then validated using the available experimental data . A sensitivity analysis is performed in the next step in order to study the effect of changing the type of the working fluid and the corresponding Reynolds number on the overall performance of the system. The potential improvement due to the addition of a shield on the upper half of the annulus and enhancing the convection coefficient of the heat transfer fluid is also studied.

Parabolic Trough Reference Plant for Cost Modeling with the Solar Advisor Model (SAM)

Energy Technology Data Exchange (ETDEWEB)

Turchi, C.

2010-07-01

This report describes a component-based cost model developed for parabolic trough solar power plants. The cost model was developed by the National Renewable Energy Laboratory (NREL), assisted by WorleyParsons Group Inc., for use with NREL's Solar Advisor Model (SAM). This report includes an overview and explanation of the model, two summary contract reports from WorleyParsons, and an Excel spreadsheet for use with SAM. The cost study uses a reference plant with a 100-MWe capacity and six hours of thermal energy storage. Wet-cooling and dry-cooling configurations are considered. The spreadsheet includes capital and operating cost by component to allow users to estimate the impact of changes in component costs.

Design of a high-efficiency train headlamp with low power consumption using dual half-parabolic aluminized reflectors.

Science.gov (United States)

Liang, Wei-Lun; Su, Guo-Dung J

2018-02-20

We propose a train headlamp system using dual half-circular parabolic aluminized reflectors. Each half-circular reflector contains five high-efficiency and small-package light-emitting diode (LED) chips, and the halves are 180° rotationally symmetric. For traffic safety, the headlamp satisfies the Code of Federal Regulations. To predict the pattern of illumination, an analytical derivation is developed for the optical path of a ray that is perpendicular to and emitted from the center of an LED chip. This ray represents the main ray emitted from the LED chip and is located at the maximum illuminance of the spot projected by the LED source onto a screen. We then analyze the design systematically to determine the locations of the LED chips in the reflector that minimize electricity consumption while satisfying reliability constraints associated with traffic safety. Compared to a typical train headlamp system with an incandescent or halogen lamp needing several hundred watts, the proposed system only uses 20.18 W to achieve the luminous intensity requirements.

Study of a new solar adsorption refrigerator powered by a parabolic trough collector

International Nuclear Information System (INIS)

El Fadar, A.; Mimet, A.; Azzabakh, A.; Perez-Garcia, M.; Castaing, J.

2009-01-01

This paper presents the study of solar adsorption cooling machine, where the reactor is heated by a parabolic trough collector (PTC) and is coupled with a heat pipe (HP). This reactor contains a porous medium constituted of activated carbon, reacting by adsorption with ammonia. We have developed a model, based on the equilibrium equations of the refrigerant, adsorption isotherms, heat and mass transfer within the adsorbent bed and energy balance in the hybrid system components. From real climatic data, the model computes the performances of the machine. In comparison with other systems powered by flat plate or evacuated tube collectors, the predicted results, have illustrated the ability of the proposed system to achieve a high performance due to high efficiency of PTC, and high flux density of heat pipe

Analysis and validation of a quasi-dynamic model for a solar collector field with flat plate collectors and parabolic trough collectors in series for district heating

DEFF Research Database (Denmark)

Tian, Zhiyong; Perers, Bengt; Furbo, Simon

2018-01-01

performance of the hybrid solar district heating plants is also presented. The measured and simulated results show that the integration of parabolic trough collectors in solar district heating plants can guarantee that the system produces hot water with relatively constant outlet temperature. The daily energy......A quasi-dynamic TRNSYS simulation model for a solar collector field with flat plate collectors and parabolic trough collectors in series was described and validated. A simplified method was implemented in TRNSYS in order to carry out long-term energy production analyses of the whole solar heating...... plant. The advantages of the model include faster computation with fewer resources, flexibility of different collector types in solar heating plant configuration and satisfactory accuracy in both dynamic and long-term analyses. In situ measurements were taken from a pilot solar heating plant with 5960 m...

Technical Manual for the SAM Physical Trough Model

Energy Technology Data Exchange (ETDEWEB)

Wagner, M. J.; Gilman, P.

2011-06-01

NREL, in conjunction with Sandia National Lab and the U.S Department of Energy, developed the System Advisor Model (SAM) analysis tool for renewable energy system performance and economic analysis. This paper documents the technical background and engineering formulation for one of SAM's two parabolic trough system models in SAM. The Physical Trough model calculates performance relationships based on physical first principles where possible, allowing the modeler to predict electricity production for a wider range of component geometries than is possible in the Empirical Trough model. This document describes the major parabolic trough plant subsystems in detail including the solar field, power block, thermal storage, piping, auxiliary heating, and control systems. This model makes use of both existing subsystem performance modeling approaches, and new approaches developed specifically for SAM.

LCOE reduction potential of parabolic trough and solar tower CSP technology until 2025

Science.gov (United States)

Dieckmann, Simon; Dersch, Jürgen; Giuliano, Stefano; Puppe, Michael; Lüpfert, Eckhard; Hennecke, Klaus; Pitz-Paal, Robert; Taylor, Michael; Ralon, Pablo

2017-06-01

Concentrating Solar Power (CSP), with an installed capacity of 4.9 GW by 2015, is a young technology compared to other renewable power generation technologies. A limited number of plants and installed capacity in a small challenging market environment make reliable and transparent cost data for CSP difficult to obtain. The International Renewable Energy Agency (IRENA) and the DLR German Aerospace Center gathered and evaluated available cost data from various sources for this publication in order to yield transparent, reliable and up-to-date cost data for a set of reference parabolic trough and solar tower plants in the year 2015 [1]. Each component of the power plant is analyzed for future technical innovations and cost reduction potential based on current R&D activities, ongoing commercial developments and growth in market scale. The derived levelized cost of electricity (LCOE) for 2015 and 2025 are finally contrasted with published power purchase agreements (PPA) of the NOOR II+III power plants in Morocco. At 7.5% weighted average cost of capital (WACC) and 25 years economic life time, the levelized costs of electricity for plants with 7.5 (trough) respectively 9 (tower) full-load hours thermal storage capacity decrease from 14-15 -ct/kWh today to 9-10 -ct/kWh by 2025 for both technologies at direct normal irradiation of 2500 kWh/(m².a). The capacity factor increases from 41.1% to 44.6% for troughs and from 45.5% to 49.0% for towers. Financing conditions are a major cost driver and offer potential for further cost reduction with the maturity of the technology and low interest rates (6-7 - ct/kWh for 2% WACC at 2500 kWh/(m2.a) in 2025).

Solar photovoltaic reflective trough collection structure

Science.gov (United States)

Anderson, Benjamin J.; Sweatt, William C.; Okandan, Murat; Nielson, Gregory N.

2015-11-19

A photovoltaic (PV) solar concentration structure having at least two troughs encapsulated in a rectangular parallelepiped optical plastic structure, with the troughs filled with an optical plastic material, the troughs each having a reflective internal surface and approximately parabolic geometry, and the troughs each including photovoltaic cells situated so that light impinging on the optical plastic material will be concentrated onto the photovoltaic cells. Multiple structures can be connected to provide a solar photovoltaic collection system that provides portable, efficient, low-cost electrical power.

Strategic Plan Outline for the Army Utilities Modernization Program: Fiscal Years 2008-2013

Science.gov (United States)

2006-11-01

mechanism to keep the trough reflector pointed at the sun throughout the day, and compound parabolic concentrating collectors , which do not re- quire... collectors are used in commercial and industrial applications and are of the following types: parabolic -trough collectors , which use a tracking...section of a PV cell ...................................................................................................149 H9 Solar collector types

Performance Analysis and Optimization of a Parabolic Trough Solar Power Plant in the Middle East Region

Directory of Open Access Journals (Sweden)

Praveen R. P.

2018-03-01

Full Text Available The Middle East is one among the areas of the world that receive high amounts of direct solar radiation. As such, the region holds a promising potential to leverage clean energy. Owing to rapid urbanization, energy demands in the region are on the rise. Along with the global push to curb undesirable outcomes such as air pollution, emissions of greenhouse gases, and climate change, an urgent need has arisen to explore and exploit the abundant renewable energy sources. This paper presents the design, performance analysis and optimization of a 100 MWe parabolic trough collector Solar Power Plant with thermal energy storage intended for use in the Middle Eastern regions. Two representative sites in the Middle East which offer an annual average direct normal irradiance (DNI of more than 5.5 kWh/m2/day has been chosen for the analysis. The thermodynamic aspect and annual performance of the proposed plant design is also analyzed using the System Advisor Model (SAM version 2017.9.5. Based on the analysis carried out on the initial design, annual power generated from the proposed concentrating solar power (CSP plant design in Abu Dhabi amounts to 333.15 GWh whereas that in Aswan recorded a value of 369.26 GWh, with capacity factors of 38.1% and 42.19% respectively. The mean efficiency of the plants in Abu Dhabi and Aswan are found to be 14.35% and 14.98% respectively. The optimization of the initial plant design is also carried out by varying two main design parameters, namely the solar multiple and full load hours of thermal energy storage (TES. Based on the findings of the study, the proposed 100 MW parabolic trough collector solar power plant with thermal energy storage can contribute to the sustainable energy future of the Middle East with reduced dependency on fossil fuels.

Economic optimization of a Kalina cycle for a parabolic trough solar thermal power plant

DEFF Research Database (Denmark)

Modi, Anish; Kærn, Martin Ryhl; Andreasen, J. G.

2015-01-01

-water mixture evaporates and condenses with a temperature glide, thus providing a better match with the heat source/sink temperature profile. This better match results in reduced thermal irreversibility, but at the cost of relatively larger heat exchanger areas. The parabolic trough collector is the most mature...... heat transfer correlations, and appropriate cost functions were used to estimate the costs for the various plant components. The optimal capital investment costs were determined for several values of the turbine inlet ammonia mass fraction and among the compared cases, the Kalina cycle has the minimum......The Kalina cycle has recently seen increased interest as a replacement for the more traditional steam Rankine cycle for geothermal, solar, ocean thermal energy conversion and waste heat recovery applications. The Kalina cycle uses a mixture of ammonia and water as the working fluid. The ammonia...

Heat transfer analysis of parabolic trough solar receiver

International Nuclear Information System (INIS)

Padilla, Ricardo Vasquez; Demirkaya, Gokmen; Goswami, D. Yogi; Stefanakos, Elias; Rahman, Muhammad M.

2011-01-01

Highlights: → In this paper a detailed one dimensional numerical heat transfer analysis of a PTC is performed. → The receiver and envelope were divided into several segments and mass and energy balance were applied in each segment. → Improvements either in the heat transfer correlations or radiative heat transfer analysis are presented. → The proposed heat transfer model was validated with experimental data obtained from Sandia National Laboratory. → Our results showed a better agreement with experimental data compared to other models. -- Abstract: Solar Parabolic Trough Collectors (PTCs) are currently used for the production of electricity and applications with relatively higher temperatures. A heat transfer fluid circulates through a metal tube (receiver) with an external selective surface that absorbs solar radiation reflected from the mirror surfaces of the PTC. In order to reduce the heat losses, the receiver is covered by an envelope and the enclosure is usually kept under vacuum pressure. The heat transfer and optical analysis of the PTC is essential to optimize and understand its performance under different operating conditions. In this paper a detailed one dimensional numerical heat transfer analysis of a PTC is performed. The receiver and envelope were divided into several segments and mass and energy balance were applied in each segment. Improvements either in the heat transfer correlations or radiative heat transfer analysis are presented as well. The partial differential equations were discretized and the nonlinear algebraic equations were solved simultaneously. Finally, to validate the numerical results, the model was compared with experimental data obtained from Sandia National Laboratory (SNL) and other one dimensional heat transfer models. Our results showed a better agreement with experimental data compared to other models.

Development of Full-Scale Ultrathin Shell Reflector

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Durmuş Türkmen

2012-01-01

Full Text Available It is aimed that a new ultrathin shell composite reflector is developed considering different design options to optimize the stiffness/mass ratio, cost, and manufacturing. The reflector is an offset parabolic reflector with a diameter of 6 m, a focal length of 4.8 m, and an offset of 0.3 m and has the ability of folding and self-deploying. For Ku-band missions a full-scale offset parabolic reflector antenna is designed by considering different concepts of stiffening: (i reflective surface and skirt, (ii reflective surface and radial ribs, and (iii reflective surface, skirt, and radial ribs. In a preliminary study, the options are modeled using ABAQUS finite element program and compared with respect to their mass, fundamental frequency, and thermal surface errors. It is found that the option of reflective surface and skirt is more advantageous. The option is further analyzed to optimize the stiffness/mass ratio considering the design parameters of material thickness, width of the skirt, and ply angles. Using the TOPSIS method is determined the best reflector concept among thirty different designs. Accordingly, new design can be said to have some advantages in terms of mass, natural frequency, number of parts, production, and assembly than both SSBR and AstroMesh reflectors.

Optimising position control of a solar parabolic trough

Directory of Open Access Journals (Sweden)

Puramanathan Naidoo

2011-03-01

Full Text Available In today’s climate of growing energy needs and increasing environmental concerns, alternatives to the use of non-renewable and polluting fossil fuels have to be investigated. One such alternative is solar energy. This study is based on the implementation of a mathematical computation – the PSA (Plataforma Solar de Almeria computation developed at PSA (the European Test Centre for solar energy applications – embedded in a control algorithm to locate the position of the sun. Tests were conducted on a solar parabolic trough (SPT constructed at the Solar Thermal Applications Research Laboratory of the Mangosuthu University of Technology (Durban, South Africa for optimal position control using the PSA value. The designed control algorithm embedded in an industrial Siemens S7-314 C-2PtP programmable logic controller compared the PSA computation to a measured position of the SPT to optimally rotate the SPT to a desired position with the constant movement of the sun. The two main angles of the sun relative to the position of the SPT on earth, the zenith angle and the azimuth angle, both calculated in the PSA from the vertical and horizontal planes, respectively, were applied to the control algorithm to generate an appropriate final tracking angle within a 0.007 radian (0° 24′ 3.6″ tolerance, in accordance to the construction specifications and solar collector testing standards of the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE, 1991. These values, together with the longitude and latitude applicable to the geographical location of the SPT, were processed in the control software to rotate the SPT to an optimal position with respect to the position of the sun in its daily path, for solar-to-thermal conversion.

Wirelessly Controllable Inflated Electroactive Polymer (EAP) Reflectors

Science.gov (United States)

Bao, Xiaoqi; Bar-Cohen, Yoseph; Chang, Zensheu; Sherrit, Stewart; Badescu, Mircea

2005-01-01

Inflatable membrane reflectors are attractive for deployable, large aperture, lightweight optical and microwave systems in micro-gravity space environment. However, any fabrication flaw or temperature variation may results in significant aberration of the surface. Even for a perfectly fabricated inflatable membrane mirror with uniform thickness, theory shows it will form a Hencky curve surface but a desired parabolic or spherical surface. Precision control of the surfaceshape of extremely flexible membrane structures is a critical challenge for the success of this technology. Wirelessly controllable inflated reflectors made of electroactive polymers (EAP) are proposed in this paper. A finite element model was configured to predict the behavior of the inflatable EAP membranes under pre-strains, pressures and distributed electric charges on the surface. To explore the controllability of the inflatable EAP reflectors, an iteration algorism was developed to find the required electric actuation for correcting the aberration of the Hencky curve to the desired parabolic curve. The correction capability of the reflectors with available EAP materials was explored numerically and is presented in this paper.

Thermal and optical study of parabolic trough collectors of Shiraz solar power plant

Energy Technology Data Exchange (ETDEWEB)

Mokhtari, A.; Yaghoubi, M.; Vadiee, A.; Hessami, R. [Shiraz Univ, Shiraz (Iran, Islamic Republic of); Kanan, P. [Renewable Energy Organization of Iran, Tehran (Iran, Islamic Republic of)

2007-07-01

The construction of the first 250 KW solar power plant in Shiraz, Iran was discussed. The power plant is comprised of a steam and oil cycle which includes 48 parabolic trough collectors (PTCs). Solar thermal power plants based on PTCs are currently the most successful solar technologies for electricity generation. These power plants are basically composed of a solar collector field and a power block. The solar collector field is designed to collect heat from the sun which it is continuously tracking. The reflecting surface concentrates direct solar radiation in the optical focal line of the collector where the heat collecting element (HCE) is located. The HCE absorbs the reflected energy and transmits it to the heat transfer fluid which is pumped to the conventional power block where electricity is generated. There is potential to significantly increase the performance and reduce the cost of PTC solar thermal electric technologies. However, it is necessary to characterize the optical performance and determine the optical losses of PTCs in order to improve the optical efficiency of these systems and to ensure the desired power quality. In this study, thermocouple sensors were used to record the collector oil inlet and outlet temperature along with the ambient temperature in the PTCs. In addition to measuring the wind speed, the solar beam radiation intensity was measured along with the oil's mass flow rate. All parameters were measured as a function of time. Based on these measurements, the intercept factor value and collector's incidence angle was determined and compared with other large size constructed commercial parabolic collectors. The maximum beam radiation during the experimental period was 735 2mW. The useful heat gain and the collector's instantaneous efficiency as a whole was evaluated on an hourly basis. All these parameters were strongly influenced by the incident beam radiation and found to follow each other. The optical and thermal

Design and Implementation of PLC-Based Automatic Sun tracking System for Parabolic Trough Solar Concentrator

Directory of Open Access Journals (Sweden)

Wang Jinping

2016-01-01

Full Text Available A sun-tracking system for parabolic trough solar concentrators (PTCs is a control system used to orient the concentrator toward the sun always, so that the maximum energy can be collected. The work presented here is a design and development of PLC based sun tracking control system for PTC. Sun tracking control system consists of a Programmable Logic Controller (PLC and a single axis hydraulic drives tracking control system. Hydraulic drives and the necessary tracking angle algorithm have been designed and developed to perform the technical tasks. A PLC unit was employed to control and monitor the mechanical movement of the PTC and to collect and store data related to the tracking angle of PTC. It is found that the tracking error of the system is less than 0.6°. Field experience shows that tracking algorithm act stable and reliable and suit for PTCs.

Dynamic Modeling of the Solar Field in Parabolic Trough Solar Power Plants

Directory of Open Access Journals (Sweden)

Lourdes A. Barcia

2015-11-01

Full Text Available Parabolic trough solar power plants use a thermal fluid to transfer thermal energy from solar radiation to a water-steam Rankine cycle in order to drive a turbine that, coupled to an electrical generator, produces electricity. These plants have a heat transfer fluid (HTF system with the necessary elements to transform solar radiation into heat and to transfer that thermal energy to the water-steam exchangers. In order to get the best possible performance in the Rankine cycle and, hence, in the thermal plant, it is necessary that the thermal fluid reach its maximum temperature when leaving the solar field (SF. Also, it is mandatory that the thermal fluid does not exceed the maximum operating temperature of the HTF, above which it degrades. It must be noted that the optimal temperature of the thermal fluid is difficult to obtain, since solar radiation can change abruptly from one moment to another. The aim of this document is to provide a model of an HTF system that can be used to optimize the control of the temperature of the fluid without interfering with the normal operation of the plant. The results obtained with this model will be contrasted with those obtained in a real plant.

Simulation of solar lithium bromide-water absorption cooling system with parabolic trough collector

International Nuclear Information System (INIS)

Mazloumi, M.; Naghashzadegan, M.; Javaherdeh, K.

2008-01-01

Ahwaz is one of the sweltering cities in Iran where an enormous amount of energy is being consumed to cool residential places in a year. The aim of this research is to simulate a solar single effect lithium bromide-water absorption cooling system in Ahwaz. The solar energy is absorbed by a horizontal N-S parabolic trough collector and stored in an insulated thermal storage tank. The system has been designed to supply the cooling load of a typical house where the cooling load peak is about 17.5 kW (5 tons of refrigeration), which occurs in July. A thermodynamic model has been used to simulate the absorption cycle. The working fluid is water, which is pumped directly to the collector. The results showed that the collector mass flow rate has a negligible effect on the minimum required collector area, but it has a significant effect on the optimum capacity of the storage tank. The minimum required collector area was about 57.6 m 2 , which could supply the cooling loads for the sunshine hours of the design day for July. The operation of the system has also been considered after sunset by saving solar energy

Optimized molten salt receivers for ultimate trough solar fields

Science.gov (United States)

Riffelmann, Klaus-J.; Richert, Timo; Kuckelkorn, Thomas

2016-05-01

Today parabolic trough collectors are the most successful concentrating solar power (CSP) technology. For the next development step new systems with increased operation temperature and new heat transfer fluids (HTF) are currently developed. Although the first power tower projects have successfully been realized, up to now there is no evidence of an all-dominant economic or technical advantage of power tower or parabolic trough. The development of parabolic trough technology towards higher performance and significant cost reduction have led to significant improvements in competitiveness. The use of molten salt instead of synthetic oil as heat transfer fluid will bring down the levelized costs of electricity (LCOE) even further while providing dispatchable energy with high capacity factors. FLABEG has developed the Ultimate TroughTM (UT) collector, jointly with sbp Sonne GmbH and supported by public funds. Due to its validated high optical accuracy, the collector is very suitable to operate efficiently at elevated temperatures up to 550 °C. SCHOTT will drive the key-innovations by introducing the 4th generation solar receiver that addresses the most significant performance and cost improvement measures. The new receivers have been completely redesigned to provide a product platform that is ready for high temperature operation up to 550 °C. Moreover distinct product features have been introduced to reduce costs and risks in solar field assembly and installation. The increased material and design challenges incurred with the high temperature operation have been reflected in sophisticated qualification and validation procedures.

Thermo-economic optimization of a hybrid solar district heating plant with flat plate collectors and parabolic trough collectors in series

DEFF Research Database (Denmark)

Tian, Zhiyong; Perers, Bengt; Furbo, Simon

2018-01-01

heating network in this study. The results also show that parabolic trough collectors are economically feasible for district heating networks in Denmark. The generic and multivariable levelized cost of heat method can guide engineers and designers on the design, construction and control of large...... to optimize the hybrid solar district heating systems based on levelized cost of heat. It is found that the lowest net levelized cost of heat of hybrid solar heating plants could reach about 0.36 DKK/kWh. The system levelized cost of heat can be reduced by 5–9% by use of solar collectors in the district...

Efficient Extraction of Light from a Nitrogen-Vacancy Center in a Diamond Parabolic Reflector.

Science.gov (United States)

Wan, Noel H; Shields, Brendan J; Kim, Donggyu; Mouradian, Sara; Lienhard, Benjamin; Walsh, Michael; Bakhru, Hassaram; Schröder, Tim; Englund, Dirk

2018-04-03

Quantum emitters in solids are being developed for a range of quantum technologies, including quantum networks, computing, and sensing. However, a remaining challenge is the poor photon collection due to the high refractive index of most host materials. Here we overcome this limitation by introducing monolithic parabolic reflectors as an efficient geometry for broadband photon extraction from quantum emitter and experimentally demonstrate this device for the nitrogen-vacancy (NV) center in diamond. Simulations indicate a photon collection efficiency exceeding 75% across the visible spectrum and experimental devices, fabricated using a high-throughput gray scale lithography process, demonstrating a photon extraction efficiency of (41 ± 5)%. This device enables a raw experimental detection efficiency of (12 ± 1)% with fluorescence detection rates as high as (4.114 ± 0.003) × 10 6 counts per second (cps) from a single NV center. Enabled by our deterministic emitter localization and fabrication process, we find a high number of exceptional devices with an average count rate of (3.1 ± 0.9) × 10 6 cps.

Some characteristics of heat production by stationary parabolic, cylindrical solar concentrator

Energy Technology Data Exchange (ETDEWEB)

Bojic, M.; Marjanovic, N.; Miletic, I.; Mitic, A. [Kragujevac Univ., Kragujevac (Serbia). Faculty of Mechanical Engineering; Stefanovic, V. [Nis Univ., Nis (Serbia). Faculty of Mechanical Engineering

2009-07-01

The use of solar energy for heating, cooling and electricity production was discussed with particular reference to the use of a stationary, asymmetric solar concentrator for conversion of solar energy to heat using a reflector and absorber. The infinite length CP-0A type stationary parabolic, cylindrical solar concentrator for heat production consists of the absorber (with water pipes) and parabolic, cylindrical reflector (with a metal surface). It has a geometrical concentration ratio of up to 4. This paper reported on a study that used the CATIA computer software to investigate how direct solar radiation approaches the concentrator aperture and the concentrator reflector. The propagation of light rays inside the concentrator to reach the absorber surface was examined. The study showed that the solar ray either hits the absorber directly or it bounces one or several time from the concentrator reflector. The efficiency of light rays was also calculated as a function of angles of incident of solar rays and type of reflector surface. 5 refs., 8 figs.

Optimization, selection and feasibility study of solar parabolic trough power plants for Algerian conditions

International Nuclear Information System (INIS)

Boukelia, T.E.; Mecibah, M.S.; Kumar, B.N.; Reddy, K.S.

2015-01-01

Highlights: • Evaluation of solar resources in the absence of measured data. • Optimization of 2 PTSTPPs integrated with TES and FBS and using oil and salt as HTFs. • 4E comparative study of the two optimized plants alongside the Andasol 1 plant. • The salt plant resulting as the best one and has been chosen for the viability study. • Tamanrasset is the best location for construction of PTSTPPs. - Abstract: In the present study, optimization of two parabolic trough solar thermal power plants integrated with thermal energy storage (TES), and fuel backup system (FBS) has been performed. The first plant uses Therminol VP-1 as heat transfer fluid in the solar field and the second plant uses molten salt. The optimization is carried out with solar multiple (SM) and full load hours of TES as the parameters, with an objective of minimizing the levelized cost of electricity (LCOE) and maximizing the annual energy yield. A 4E (energy–exergy–environment–economic) comparison of the optimized plants alongside the Andasol 1 as reference plant is studied. The molten salt plant resulting as the best technology, from the optimization and 4E comparative study has been chosen for the viability analysis of ten locations in Algeria with semi-arid and arid climatic conditions. The results indicate that Andasol 1 reference plant has the highest mean annual energy efficiency (17.25%) and exergy efficiency (23.30%). Whereas, the highest capacity factor (54.60%) and power generation (236.90 GW h) are exhibited by the molten salt plant. The molten salt plant has least annual water usage of about 800,482 m 3 , but demands more land for the operation. Nevertheless the oil plant emits the lowest amount of CO 2 gas (less than 40.3 kilo tonnes). From the economic viewpoint, molten salt seems to be the best technology compared to other plants due to its lowest investment cost (less than 360 million dollars) and lower levelized cost of electricity (LCOE) (8.48 ¢/kW h). The

Photovoltaic applications of Compound Parabolic Concentrator (CPC)

Science.gov (United States)

Winston, R.

1975-01-01

The use of a compound parabolic concentrator as field collector, in conjunction with a primary focusing concentrator for photovoltaic applications is studied. The primary focusing concentrator can be a parabolic reflector, an array of Fresnel mirrors, a Fresnel lens or some other lens. Silicon solar cell grid structures are proposed that increase efficiency with concentration up to 10 suns. A ray tracing program has been developed to determine energy distribution at the exit of a compound parabolic concentrator. Projected total cost of a CPC/solar cell system will be between 4 and 5 times lower than for flat plate silicon cell arrays.

Achieving uniform efficient illumination with multiple asymmetric compound parabolic luminaires

Science.gov (United States)

Gordon, Jeffrey M.; Kashin, Peter

1994-01-01

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

Surface accuracy analysis and mathematical modeling of deployable large aperture elastic antenna reflectors

Science.gov (United States)

Coleman, Michael J.

One class of deployable large aperture antenna consists of thin light-weight parabolic reflectors. A reflector of this type is a deployable structure that consists of an inflatable elastic membrane that is supported about its perimeter by a set of elastic tendons and is subjected to a constant hydrostatic pressure. A design may not hold the parabolic shape to within a desired tolerance due to an elastic deformation of the surface, particularly near the rim. We can compute the equilibrium configuration of the reflector system using an optimization-based solution procedure that calculates the total system energy and determines a configuration of minimum energy. Analysis of the equilibrium configuration reveals the behavior of the reflector shape under various loading conditions. The pressure, film strain energy, tendon strain energy, and gravitational energy are all considered in this analysis. The surface accuracy of the antenna reflector is measured by an RMS calculation while the reflector phase error component of the efficiency is determined by computing the power density at boresight. Our error computation methods are tailored for the faceted surface of our model and they are more accurate for this particular problem than the commonly applied Ruze Equation. Previous analytical work on parabolic antennas focused on axisymmetric geometries and loads. Symmetric equilibria are not assumed in our analysis. In addition, this dissertation contains two principle original findings: (1) the typical supporting tendon system tends to flatten a parabolic reflector near its edge. We find that surface accuracy can be significantly improved by fixing the edge of the inflated reflector to a rigid structure; (2) for large membranes assembled from flat sheets of thin material, we demonstrate that the surface accuracy of the resulting inflated membrane reflector can be improved by altering the cutting pattern of the flat components. Our findings demonstrate that the proper choice

Performance Evaluation of Dual-axis Tracking System of Parabolic Trough Solar Collector

Science.gov (United States)

Ullah, Fahim; Min, Kang

2018-01-01

A parabolic trough solar collector with the concentration ratio of 24 was developed in the College of Engineering; Nanjing Agricultural University, China with the using of the TracePro software an optical model built. Effects of single-axis and dual-axis tracking modes, azimuth and elevating angle tracking errors on the optical performance were investigated and the thermal performance of the solar collector was experimentally measured. The results showed that the optical efficiency of the dual-axis tracking was 0.813% and its year average value was 14.3% and 40.9% higher than that of the eat-west tracking mode and north-south tracking mode respectively. Further, form the results of the experiment, it was concluded that the optical efficiency was affected significantly by the elevation angle tracking errors which should be kept below 0.6o. High optical efficiency could be attained by using dual-tracking mode even though the tracking precision of one axis was degraded. The real-time instantaneous thermal efficiency of the collector reached to 0.775%. In addition, the linearity of the normalized efficiency was favorable. The curve of the calculated thermal efficiency agreed well with the normalized instantaneous efficiency curve derived from the experimental data and the maximum difference between them was 10.3%. This type of solar collector should be applied in middle-scale thermal collection systems.

Two-stage solar concentrators based on parabolic troughs: asymmetric versus symmetric designs.

Science.gov (United States)

Schmitz, Max; Cooper, Thomas; Ambrosetti, Gianluca; Steinfeld, Aldo

2015-11-20

While nonimaging concentrators can approach the thermodynamic limit of concentration, they generally suffer from poor compactness when designed for small acceptance angles, e.g., to capture direct solar irradiation. Symmetric two-stage systems utilizing an image-forming primary parabolic concentrator in tandem with a nonimaging secondary concentrator partially overcome this compactness problem, but their achievable concentration ratio is ultimately limited by the central obstruction caused by the secondary. Significant improvements can be realized by two-stage systems having asymmetric cross-sections, particularly for 2D line-focus trough designs. We therefore present a detailed analysis of two-stage line-focus asymmetric concentrators for flat receiver geometries and compare them to their symmetric counterparts. Exemplary designs are examined in terms of the key optical performance metrics, namely, geometric concentration ratio, acceptance angle, concentration-acceptance product, aspect ratio, active area fraction, and average number of reflections. Notably, we show that asymmetric designs can achieve significantly higher overall concentrations and are always more compact than symmetric systems designed for the same concentration ratio. Using this analysis as a basis, we develop novel asymmetric designs, including two-wing and nested configurations, which surpass the optical performance of two-mirror aplanats and are comparable with the best reported 2D simultaneous multiple surface designs for both hollow and dielectric-filled secondaries.

Thermal Energy Recovery through Optimal Salt concentration in a Parabolic Trough Systems

Directory of Open Access Journals (Sweden)

Ramsurn Rikesh

2018-01-01

Full Text Available Making a PVT system hybrid is to support the use of thermal and electrical energy simultaneously or independently, to control the thermal effect to improve electrical efficiency or vice-versa. This project makes use of the Parabolic Trough design with emphasis on making the system to be sustainable and also increasing the thermal efficiency of the system. Polystyrene and acrylic foam is utilized to maximize the heat retention capability of the system. To power, the pump that moves the heat transfer fluid (tested with salt water proportions within the copper tube, a set of solar PV panel is to support its power demand making it sustainable. The closed loop setup designed achieved an improved thermal efficiency level of 66.2%, which contributes to having a reliable heat energy source for applications such as hot showers. The novel setup design also makes use of PV cells to support other energy demands through power electronic control designs. Using a similar heat dissipation technique, a novel setup has been designed to improve the voltage supply by making use of liquid cooling and translucent glass PV panels. Cooling the PV panel restored up to 11.7% of its rated voltage supply. This is achieved by keeping the PV panels within its best thermal operating conditions using an energy efficient electronically controlled cooling system.

Optical analysis of a photovoltaic V-trough system installed in western India.

Science.gov (United States)

Maiti, Subarna; Sarmah, Nabin; Bapat, Pratap; Mallick, Tapas K

2012-12-20

The low concentrating photovoltaic (PV) system such as a 2× V-trough system can be a promising choice for enhancing the power output from conventional PV panels with the inclusion of thermal management. This system is more attractive when the reflectors are retrofitted to the stationary PV panels installed in a high aspect ratio in the north-south direction and are tracked 12 times a year manually according to preset angles, thus eliminating the need of diurnal expensive tracking. In the present analysis, a V-trough system facing exactly the south direction is considered, where the tilt angle of the PV panels' row is kept constant at 18.34°. The system is installed on the terrace of CSIR-Central Salt and Marine Chemicals Research Institute in Bhavnagar, Gujarat, India (21.47 N, 71.15 E). The dimension of the entire PV system is 9.64 m×0.55 m. The V-troughs made of anodized aluminum reflectors (70% specular reflectivity) had the same dimensions. An in-house developed; experimentally validated Monte Carlo ray-trace model was used to study the effect of the angular variation of the reflectors throughout a year for the present assembly. Results of the ray trace for the optimized angles showed the maximum simulated optical efficiency to be 85.9%. The spatial distribution of solar intensity over the 0.55 m dimension of the PV panel due to the V-trough reflectors was also studied for the optimized days in periods that included solstices and equinoxes. The measured solar intensity profiles with and without the V-trough system were used to calculate the actual optical efficiencies for several sunny days in the year, and results were validated with the simulated efficiencies within an average error limit of 10%.

Optimization of a Solar-Driven Trigeneration System with Nanofluid-Based Parabolic Trough Collectors

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Evangelos Bellos

2017-06-01

Full Text Available The objective of this work was to optimize and to evaluate a solar-driven trigeneration system which operates with nanofluid-based parabolic trough collectors. The trigeneration system includes an organic Rankine cycle (ORC and an absorption heat pump operating with LiBr-H2O which is powered by the rejected heat of the ORC. Toluene, n-octane, Octamethyltrisiloxane (MDM and cyclohexane are the examined working fluids in the ORC. The use of CuO and Al2O3 nanoparticles in the Syltherm 800 (base fluid is investigated in the solar field loop. The analysis is performed with Engineering Equation Solver (EES under steady state conditions in order to give the emphasis in the exergetic optimization of the system. Except for the different working fluid investigation, the system is optimized by examining three basic operating parameters in all the cases. The pressure in the turbine inlet, the temperature in the ORC condenser and the nanofluid concentration are the optimization variables. According to the final results, the combination of toluene in the ORC with the CuO nanofluid is the optimum choice. The global maximum exergetic efficiency is 24.66% with pressure ratio is equal to 0.7605, heat rejection temperature 113.7 °C and CuO concentration 4.35%.

On-line monitoring of H2 generation and the HTF degradation in parabolic trough solar thermal power plants: Development of an optical sensor based on an innovative approach

Science.gov (United States)

Pagola, Iñigo; Funcia, Ibai; Sánchez, Marcelino; Gil, Javier; González-Vallejo, Victoria; Bedoya, Maxi; Orellana, Guillermo

2017-06-01

The work presented in this paper offers a robust, effective and economically competitive method for online detection and monitoring of the presence of molecular hydrogen in the heat transfer fluids of parabolic trough collector plants. The novel method is based on a specific fluorescent sensor according to the ES2425002 patent ("Method for the detection and quantification of hydrogen in a heat transfer fluid").

A Monte Carlo method and finite volume method coupled optical simulation method for parabolic trough solar collectors

International Nuclear Information System (INIS)

Liang, Hongbo; Fan, Man; You, Shijun; Zheng, Wandong; Zhang, Huan; Ye, Tianzhen; Zheng, Xuejing

2017-01-01

Highlights: •Four optical models for parabolic trough solar collectors were compared in detail. •Characteristics of Monte Carlo Method and Finite Volume Method were discussed. •A novel method was presented combining advantages of different models. •The method was suited to optical analysis of collectors with different geometries. •A new kind of cavity receiver was simulated depending on the novel method. -- Abstract: The PTC (parabolic trough solar collector) is widely used for space heating, heat-driven refrigeration, solar power, etc. The concentrated solar radiation is the only energy source for a PTC, thus its optical performance significantly affects the collector efficiency. In this study, four different optical models were constructed, validated and compared in detail. On this basis, a novel coupled method was presented by combining advantages of these models, which was suited to carry out a mass of optical simulations of collectors with different geometrical parameters rapidly and accurately. Based on these simulation results, the optimal configuration of a collector with highest efficiency can be determined. Thus, this method was useful for collector optimization and design. In the four models, MCM (Monte Carlo Method) and FVM (Finite Volume Method) were used to initialize photons distribution, as well as CPEM (Change Photon Energy Method) and MCM were adopted to describe the process of reflecting, transmitting and absorbing. For simulating reflection, transmission and absorption, CPEM was more efficient than MCM, so it was utilized in the coupled method. For photons distribution initialization, FVM saved running time and computation effort, whereas it needed suitable grid configuration. MCM only required a total number of rays for simulation, whereas it needed higher computing cost and its results fluctuated in multiple runs. In the novel coupled method, the grid configuration for FVM was optimized according to the “true values” from MCM of

Low-cost small scale parabolic trough collector design for manufacturing and deployment in Africa

Science.gov (United States)

Orosz, Matthew; Mathaha, Paul; Tsiu, Anadola; Taele, B. M.; Mabea, Lengeta; Ntee, Marcel; Khakanyo, Makoanyane; Teker, Tamer; Stephens, Jordan; Mueller, Amy

2016-05-01

Concentrating Solar Power is expanding its deployment on the African subcontinent, highlighting the importance of efforts to indigenize manufacturing of this technology to increase local content and therefore local economic benefits of these projects. In this study a design for manufacturing (DFM) exercise was conducted to create a locally produced parabolic trough collector (the G4 PTC). All parts were sourced or fabricated at a production facility in Lesotho, and several examples of the design were prototyped and tested with collaborators in the Government of Lesotho's Appropriate Technology Services division and the National University of Lesotho. Optical and thermal performance was simulated and experimentally validated, and pedagogical pre-commercial versions of the PTC have been distributed to higher education partners in Lesotho and Europe. The cost to produce the PTC is 180 USD/m2 for a locally manufactured heat collection element (HCE) capable of sustaining 250C operation at ~65% efficiency. A version with an imported evacuated HCE can operate at 300°C with 70% efficiency. Economically relevant applications for this locally produced PTC include industrial process heat and distributed generation scenarios where cogeneration is required.

Optical properties of nonimaging concentrators with corrugated reflectors

Science.gov (United States)

Roennelid, Mats; Perers, Bengt; Karlsson, Bjorn

1994-09-01

A ray tracing study has been performed on the optical properties of cylindrical nonimaging concentrators with linear corrugated reflectors. The corrugations are assumed to be V-formed and to have an extension parallel to the meridian plane of the concentrators. It is shown that the acceptance angle for radiation incident in the meridian plane can be increased for moderate corrugations. This increased acceptance is balanced by a decreased acceptance of radiation from other directions. Calculations of angular acceptance for a 2X compound parabolic concentrator is presented. It is shown that the annual irradiation on a solar collector with booster reflector can be increased if corrugated reflectors are used instead of smooth reflectors.

Modeling and simulations of a 30 MWe solar electric generating system using parabolic trough collectors in Turkey

Energy Technology Data Exchange (ETDEWEB)

Usta, Yasemin [Anyl Asansor Ltd (Turkey)], email: syusta@gmail.com; Baker, Derek [Middle East Technical University (Turkey)], email: dbaker@metu.edu.tr; Kaftanoglu, Bilgin [Atilim University (Turkey)], email: bilgink@atilim.edu.tr

2011-07-01

With the energy crisis and the increasing concerns about climate change, the interest in concentrating solar power (CSP) systems is growing in Turkey. The aim of this paper is to develop a model of a CSP system using a field of parabolic trough collectors and to assess the predicted performance of the system. A model was developed for a 30MWe solar generating system in Antalya, Turkey, using TRNSYS software, the solar thermal electric components library and information on an existing system in Kramer Junction, California, United States. Annual simulations were then performed for both systems in Antalya and California using weather data. It was found that the predictions were in good agreement with published data. In addition results showed that Antalya's system would generate 30% less than Kramer Junction's system on an annual basis. This paper provides useful information on modeling and simulation of CSP systems.

Rotating Parabolic-Reflector Antenna Target in SAR Data: Model, Characteristics, and Parameter Estimation

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Bin Deng

2013-01-01

Full Text Available Parabolic-reflector antennas (PRAs, usually possessing rotation, are a particular type of targets of potential interest to the synthetic aperture radar (SAR community. This paper is aimed to investigate PRA’s scattering characteristics and then to extract PRA’s parameters from SAR returns, for supporting image interpretation and target recognition. We at first obtain both closed-form and numeric solutions to PRA’s backscattering by geometrical optics (GO, physical optics, and graphical electromagnetic computation, respectively. Based on the GO solution, a migratory scattering center model is at first presented for representing the movement of the specular point with aspect angle, and then a hybrid model, named the migratory/micromotion scattering center (MMSC model, is proposed for characterizing a rotating PRA in the SAR geometry, which incorporates PRA’s rotation into its migratory scattering center model. Additionally, we in detail analyze PRA’s radar characteristics on radar cross-section, high-resolution range profiles, time-frequency distribution, and 2D images, which also confirm the models proposed. A maximal likelihood estimator is developed for jointly solving the MMSC model for PRA’s multiple parameters by optimization. By exploiting the aforementioned characteristics, the coarse parameter estimation guarantees convergency upon global minima. The signatures recovered can be favorably utilized for SAR image interpretation and target recognition.

Performance analysis of an Integrated Solar Combined Cycle using Direct Steam Generation in parabolic trough collectors

International Nuclear Information System (INIS)

Montes, M.J.; Rovira, A.; Munoz, M.; Martinez-Val, J.M.

2011-01-01

Highlights: → Solar hybridization improves the performance of CCGT in a very hot and dry weather. → The scheme analyzed is a DSG parabolic trough field coupled to the Rankine cycle. → An annual simulation has been carried out for two locations: Almeria and Las Vegas. → Economical analysis shows that this scheme is a cheaper way to exploit solar energy. → For that, solar hybridization must be limited to a small fraction of the CCGT power. - Abstract: The contribution of solar thermal power to improve the performance of gas-fired combined cycles in very hot and dry environmental conditions is analyzed in this work, in order to assess the potential of this technique, and to feature Direct Steam Generation (DSG) as a well suited candidate for achieving very good results in this quest. The particular Integrated Solar Combined Cycle (ISCC) power plant proposed consists of a DSG parabolic trough field coupled to the bottoming steam cycle of a Combined Cycle Gas Turbine (CCGT) power plant. For this analysis, the solar thermal power plant performs in a solar dispatching mode: the gas turbine always operates at full load, only depending on ambient conditions, whereas the steam turbine is somewhat boosted to accommodate the thermal hybridization from the solar field. Although the analysis is aimed to studying such complementary effects in the widest perspective, two relevant examples are given, corresponding to two well-known sites: Almeria (Spain), with a mediterranean climate, and Las Vegas (USA), with a hot and dry climate. The annual simulations show that, although the conventional CCGT power plant works worse in Las Vegas, owing to the higher temperatures, the ISCC system operates better in Las Vegas than in Almeria, because of solar hybridization is especially well coupled to the CCGT power plant in the frequent days with great solar radiation and high temperatures in Las Vegas. The complementary effect will be clearly seen in these cases, because the thermal

Advanced Manufacture of Reflectors

Energy Technology Data Exchange (ETDEWEB)

Angel, Roger [Univ. of Arizona, Tucson, AZ (United States)

2014-12-17

The main project objective has been to develop an advanced gravity sag method for molding large glass solar reflectors with either line or point focus, and with long or short focal length. The method involves taking standard sized squares of glass, 1.65 m x 1.65 m, and shaping them by gravity sag into precision steel molds. The method is designed for high volume manufacture when incorporated into a production line with separate pre-heating and cooling. The performance objectives for the self-supporting glass mirrors made by this project include mirror optical accuracy of 2 mrad root mean square (RMS), requiring surface slope errors less than 1 mrad rms, a target not met by current production of solar reflectors. Our objective also included development of new methods for rapidly shaping glass mirrors and coating them for higher reflectivity and soil resistance. Reflectivity of 95% for a glass mirror with anti-soil coating was targeted, compared to the present ~94% with no anti-soil coating. Our mirror cost objective is ~$20/m² in 2020, a significant reduction compared to the present ~$35/m² for solar trough mirrors produced for trough solar plants.

OUT Success Stories: Solar Trough Power Plants

Science.gov (United States)

Jones, J.

2000-08-01

The Solar Electric Generating System (SEGS) plants use parabolic-trough solar collectors to capture the sun's energy and convert it to heat. The SEGS plants range in capacity from 13.8 to 80 MW, and they were constructed to meet Southern California Edison Company's periods of peak power demand.

Nonimaging reflectors for efficient uniform illumination.

Science.gov (United States)

Gordon, J M; Kashin, P; Rabl, A

1992-10-01

Nonimaging reflectors that are an extension of the design principle that was developed for compound parabolic concentrator type devices are proposed for illumination applications. The optical designs presented offer maximal lighting efficiency while they retain sharp angular control of the radiation and highly uniform flux densities on distant target planes. Our results are presented for symmetrical configurations in two dimensions (troughlike reflectors) for flat and for tubular sources. For fields of view of practical interest (half-angle in the 30-60 degrees range), these devices can achieve minimum-tomaximum intensity ratios of 0.7, while they remain compact and incur low reflective losses.

Solar parabolic dish Stirling engine system design, simulation, and thermal analysis

International Nuclear Information System (INIS)

Hafez, A.Z.; Soliman, Ahmed; El-Metwally, K.A.; Ismail, I.M.

2016-01-01

Highlights: • Modeling and simulation for different parabolic dish Stirling engine designs using Matlab®. • The effect of solar dish design features and factors had been taken. • Estimation of output power from the solar dish using Matlab®. • The present analysis provides a theoretical guidance for designing and operating solar parabolic dish system. - Abstract: Modeling and simulation for different parabolic dish Stirling engine designs have been carried out using Matlab®. The effect of solar dish design features and factors such as material of the reflector concentrators, the shape of the reflector concentrators and the receiver, solar radiation at the concentrator, diameter of the parabolic dish concentrator, sizing the aperture area of concentrator, focal Length of the parabolic dish, the focal point diameter, sizing the aperture area of receiver, geometric concentration ratio, and rim angle have been studied. The study provides a theoretical guidance for designing and operating solar parabolic dish Stirling engines system. At Zewail city of Science and Technology, Egypt, for a 10 kW Stirling engine; The maximum solar dish Stirling engine output power estimation is 9707 W at 12:00 PM where the maximum beam solar radiation applied in solar dish concentrator is 990 W/m"2 at 12:00 PM. The performance of engine can be improved by increasing the precision of the engine parts and the heat source efficiency. The engine performance could be further increased if a better receiver working fluid is used. We can conclude that where the best time for heating the fluid and fasting the processing, the time required to heat the receiver to reach the minimum temperature for operating the Solar-powered Stirling engine for different heat transfer fluids; this will lead to more economic solar dish systems. Power output of the solar dish system is one of the most important targets in the design that show effectiveness of the system, and this has achieved when we take

Shape control of slack space reflectors using modulated solar pressure.

Science.gov (United States)

Borggräfe, Andreas; Heiligers, Jeannette; Ceriotti, Matteo; McInnes, Colin R

2015-07-08

The static deflection profile of a large spin-stabilized space reflector because of solar radiation pressure acting on its surface is investigated. Such a spacecraft consists of a thin reflective circular film, which is deployed from a supporting hoop structure in an untensioned, slack manner. This paper investigates the use of a variable reflectivity distribution across the surface to control the solar pressure force and hence the deflected shape. In this first analysis, the film material is modelled as one-dimensional slack radial strings with no resistance to bending or transverse shear, which enables a semi-analytic derivation of the nominal deflection profile. An inverse method is then used to find the reflectivity distribution that generates a specific, for example, parabolic deflection shape of the strings. Applying these results to a parabolic reflector, short focal distances can be obtained when large slack lengths of the film are employed. The development of such optically controlled reflector films enables future key mission applications such as solar power collection, radio-frequency antennae and optical telescopes.

Estimation of the temperature, heat gain and heat loss by solar parabolic trough collector under Algerian climate using different thermal oils

International Nuclear Information System (INIS)

Ouagued, Malika; Khellaf, Abdallah; Loukarfi, Larbi

2013-01-01

Highlights: • Estimation of direct solar radiations for different tracking systems at six typical locations in Algeria. • PTC thermal model uses energy balances from the HTF to the atmosphere. • The model depends on the collector type, nature of HTF, optical properties, and ambient conditions. • Estimation of temperature, heat gain and energy cost of thermal oils used in the model. • Comparison between monthly mean heat gain of the various thermal oils for six Algerian locations. - Abstract: Algeria is blessed with a very important renewable, and more particularly solar, energy potential. This potential opens for Algeria reel opportunities to cope with the increasing energy demand and the growing environmental problems link to the use of fossil fuel. In order to develop and to promote concrete actions in the areas of renewable energy and energy efficiency, Algeria has introduced a national daring program for the period 2011–2030. In this program, solar energy, and more particularly solar thermal energy plays an important role. In this paper, the potential of direct solar irradiance in Algeria and the performance of solar parabolic trough collector (PTC) are estimated under the climate conditions of the country. These two factors are treated as they play an important role in the design of solar thermal plant. In order to determine the most promising solar sites in Algeria, monthly mean daily direct solar radiation have been estimated and compared for different locations corresponding to different climatic region. Different tilted and tracking collectors are considered so as to determine the most efficient system for the PTC. In order to evaluate the performance of a tracking solar parabolic trough collector, a heat transfer model is developed. The receiver, heat collector element (HCE), is divided into several segments and heat balance is applied in each segment over a section of the solar receiver. Different oils are considered to determine the thermal

Optical design of two-axes parabolic trough collector and two-section Fresnel lens for line-to-spot solar concentration.

Science.gov (United States)

Ramírez, Carlos; León, Noel; García, Héctor; Aguayo, Humberto

2015-06-01

Solar tracking concentrators are optical systems that collect the solar energy flux either in a line or spot using reflective or refractive surfaces. The main problem with these surfaces is their manufacturing complexity, especially at large scales. In this paper, a line-to-spot solar tracking concentrator is proposed. Its configuration allows for a low-cost solar concentrator system. It consists of a parabolic trough collector (PTC) and a two-section PMMA Fresnel lens (FL), both mounted on a two-axis solar tracker. The function of the PTC is to reflect the incoming solar radiation toward a line. Then, the FL, which is placed near the focus, transforms this line into a spot by refraction. It was found that the system can achieve a concentration ratio of 100x and concentrate an average solar irradiance of 518.857W/m2 with an average transmittance of 0.855, taking into account the effect of the chromatic aberration.

Simulation of thermal fluid dynamics in parabolic trough receiver tubes with direct steam generation using the computer code ATHLET

Energy Technology Data Exchange (ETDEWEB)

Hoffmann, Alexander; Merk, Bruno [Helmholtz-Zentrum Dresden-Rossendorf e.V., Dresden (Germany); Hirsch, Tobias; Pitz-Paal, Robert [DLR Deutsches Zentrum fuer Luft- und Raumfahrt e.V., Stuttgart (Germany). Inst. fuer Solarforschung

2014-06-15

In the present feasibility study the system code ATHLET, which originates from nuclear engineering, is applied to a parabolic trough test facility. A model of the DISS (DIrect Solar Steam) test facility at Plataforma Solar de Almeria in Spain is assembled and the results of the simulations are compared to measured data and the simulation results of the Modelica library 'DissDyn'. A profound comparison between ATHLET Mod 3.0 Cycle A and the 'DissDyn' library reveals the capabilities of these codes. The calculated mass and energy balance in the ATHLET simulations are in good agreement with the results of the measurements and confirm the applicability for thermodynamic simulations of DSG processes in principle. Supplementary, the capabilities of the 6-equation model with transient momentum balances in ATHLET are used to study the slip between liquid and gas phases and to investigate pressure wave oscillations after a sudden valve closure. (orig.)

Recent Developments of Reflectarray Antennas in Dual-Reflector Configurations

Directory of Open Access Journals (Sweden)

Carolina Tienda

2012-01-01

Full Text Available Recent work on dual-reflector antennas involving reflectarrays is reviewed in this paper. Both dual-reflector antenna with a reflectarray subreflector and dual-reflectarrays antennas with flat or parabolic main reflectarray are considered. First, a general analysis technique for these two configurations is described. Second, results for beam scanning and contoured-beam applications in different frequency bands are shown and discussed. The performance and capabilities of these antennas are shown by describing some practical design cases for radar, satellite communications, and direct broadcast satellite (DBS applications.

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

Science.gov (United States)

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

2012-06-01

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

Exergetic and Thermoeconomic Analyses of Solar Air Heating Processes Using a Parabolic Trough Collector

Directory of Open Access Journals (Sweden)

Miguel Ángel Hernández-Román

2014-08-01

Full Text Available This paper presents a theoretical and practical analysis of the application of the thermoeconomic method. A furnace for heating air is evaluated using the methodology. The furnace works with solar energy, received from a parabolic trough collector and with electricity supplied by an electric power utility. The methodology evaluates the process by the first and second law of thermodynamics as the first step then the cost analysis is applied for getting the thermoeconomic cost. For this study, the climatic conditions of the city of Queretaro (Mexico are considered. Two periods were taken into account: from July 2006 to June 2007 and on 6 January 2011. The prototype, located at CICATA-IPN, Qro, was analyzed in two different scenarios i.e., with 100% of electricity and 100% of solar energy. The results showed that thermoeconomic costs for the heating process with electricity, inside the chamber, are less than those using solar heating. This may be ascribed to the high cost of the materials, fittings, and manufacturing of the solar equipment. Also, the influence of the mass flow, aperture area, length and diameter of the receiver of the solar prototype is a parameter for increasing the efficiency of the prototype in addition to the price of manufacturing. The optimum design parameters are: length is 3 to 5 m, mass flow rate is 0.03 kg/s, diameter of the receiver is around 10 to 30 mm and aperture area is 3 m2.

Small-Sized Parabolic Trough Collector System for Solar Dehumidification Application: Design, Development, and Potential Assessment

Directory of Open Access Journals (Sweden)

Ghulam Qadar Chaudhary

2018-01-01

Full Text Available The current study presents a numerical and real-time performance analysis of a parabolic trough collector (PTC system designed for solar air-conditioning applications. Initially, a thermodynamic model of PTC is developed using engineering equation solver (EES having a capacity of around 3 kW. Then, an experimental PTC system setup is established with a concentration ratio of 9.93 using evacuated tube receivers. The experimental study is conducted under the climate of Taxila, Pakistan in accordance with ASHRAE 93-1986 standard. Furthermore, PTC system is integrated with a solid desiccant dehumidifier (SDD to study the effect of various operating parameters such as direct solar radiation and inlet fluid temperature and its impact on dehumidification share. The experimental maximum temperature gain is around 5.2°C, with the peak efficiency of 62% on a sunny day. Similarly, maximum thermal energy gain on sunny and cloudy days is 3.07 kW and 2.33 kW, respectively. Afterwards, same comprehensive EES model of PTC with some modifications is used for annual transient analysis in TRNSYS for five different climates of Pakistan. Quetta revealed peak solar insolation of 656 W/m2 and peak thermal energy 1139 MJ with 46% efficiency. The comparison shows good agreement between simulated and experimental results with root mean square error of around 9%.

Which is the best solar thermal collection technology for electricity generation in north-west India? Evaluation of options using the analytical hierarchy process

International Nuclear Information System (INIS)

Nixon, J.D.; Dey, P.K.; Davies, P.A.

2010-01-01

This study of concentrating solar thermal power generation sets out to evaluate the main existing collection technologies using the framework of the Analytical Hierarchy Process (AHP). It encompasses parabolic troughs, heliostat fields, linear Fresnel reflectors, parabolic dishes, compound parabolic concentrators and linear Fresnel lenses. These technologies are compared based on technical, economic and environmental criteria. Within these three categories, numerous sub-criteria are identified; similarly sub-alternatives are considered for each technology. A literature review, thermodynamic calculations and an expert workshop have been used to arrive at quantitative and qualitative assessments. The methodology is applied principally to a case study in Gujarat in north-west India, though case studies based on the Sahara Desert, Southern Spain and California are included for comparison. A sensitivity analysis is carried out for Gujarat. The study concludes that the linear Fresnel lens with a secondary compound parabolic collector, or the parabolic dish reflector, is the preferred technology for north-west India.

Which is the best solar thermal collection technology for electricity generation in north-west India? Evaluation of options using the analytical hierarchy process

Energy Technology Data Exchange (ETDEWEB)

Nixon, J.D.; Davies, P.A. [Sustainable Environment Research Group, School of Engineering and Applied Science, Aston University, Aston Triangle, Birmingham, B4 7ET (United Kingdom); Dey, P.K. [Aston Business School, Aston University, Aston Triangle, Birmingham, B4 7ET (United Kingdom)

2010-12-15

This study of concentrating solar thermal power generation sets out to evaluate the main existing collection technologies using the framework of the Analytical Hierarchy Process (AHP). It encompasses parabolic troughs, heliostat fields, linear Fresnel reflectors, parabolic dishes, compound parabolic concentrators and linear Fresnel lenses. These technologies are compared based on technical, economic and environmental criteria. Within these three categories, numerous sub-criteria are identified; similarly sub-alternatives are considered for each technology. A literature review, thermodynamic calculations and an expert workshop have been used to arrive at quantitative and qualitative assessments. The methodology is applied principally to a case study in Gujarat in north-west India, though case studies based on the Sahara Desert, Southern Spain and California are included for comparison. A sensitivity analysis is carried out for Gujarat. The study concludes that the linear Fresnel lens with a secondary compound parabolic collector, or the parabolic dish reflector, is the preferred technology for north-west India. (author)

Current status of the second generation of parabolic trough solar concentrator for heat generation process designed at the IIE; Estado actual de la segunda generacion del concentrador solar de canal parabolico para generacion de calor de proceso disenado en el IIE

Energy Technology Data Exchange (ETDEWEB)

Ramos Berumen, Carlos; Ramirez Benitez, Juan Rafael; Beltran Adan, Jose [Instituto de Investigaciones Electricas, Cuernavaca, Morelos (Mexico)]. E-mail: cramos@iie.org.mx; rramirez@iie.org.mx; jose.beltran@iie.org.mx

2010-11-15

The transformation industry normally uses thermal energy within its process, it obtains this energy burning fossils fuel, a new option is to use new technologies like the thermal solar technology like the parabolic trough, this is a long parabolic mirror used to reflect the sunlight and focused on an absorber tube with a heat-conducting fluid inside. The Instituto de Investigaciones Electricas (IIE) developed a prototype of parabolic trough that is operating in different industries, in this article are showing some improvements to the design, giving like result the second generation of the prototype of parabolic trough of the IIE. [Spanish] La industria de la transformacion normalmente utiliza energia termica dentro de su proceso, los medios convencionales para obtener esta energia es el quemar combustibles fosiles, una opcion que aplica nuevas tecnologias es el uso de la tecnologia termosolar a concentracion que le permitira a la industria utilizar el sol como fuente de energia primaria. El uso de esta tecnologia permitira a las empresas generar calor de proceso sin contaminar el ambiente, lo que dara como resultado empresas competitivas y autosuficientes. Para alcanzar temperaturas utiles a estas aplicaciones se requiere concentrar la energia solar en un area mas pequena, siendo la tecnologia mas extendida la de canal parabolico, el principio de operacion de esta tecnologia es la de concentrar la radiacion solar en el eje receptor preparado con una pintura especial para una mejor absorcion del calor y una cubierta de vidrio para evitar perdidas termicas, dentro del tubo circula un fluido caloportador el cual lleva el calor util hacia el proceso. El Instituto de Investigaciones Electricas (IIE) desarrollo un prototipo de canal parabolico, actualmente estan operando en diferentes industrias, resultado de estas aplicaciones se llevo a cabo una evaluacion del prototipo, se detectaron algunos puntos de mejoras al diseno, los cuales se exponen en este articulo, dando

Sensor for Measuring Hydrogen Partial Pressure in Parabolic Trough Power Plant Expansion Tanks

Energy Technology Data Exchange (ETDEWEB)

Glatzmaier, Greg C.; Cooney, Daniel A.

2017-06-27

The National Renewable Energy Laboratory and Acciona Energy North America are working together to design and implement a process system that provides a permanent solution to the issue of hydrogen buildup at parabolic trough power plants. We are pursuing a method that selectively removes hydrogen from the expansion tanks that serve as reservoirs for the heat transfer fluid (HTF) that circulates in the collector field and power block components. Our modeling shows that removing hydrogen from the expansion tanks at a design rate reduces and maintains dissolved hydrogen in the circulating HTF to a selected target level. Our collaborative work consists of several tasks that are needed to advance this process concept to a development stage, where it is ready for implementation at a commercial power plant. Our main effort is to design and evaluate likely process-unit operations that remove hydrogen from the expansion tanks at a specified rate. Additionally, we designed and demonstrated a method and instrumentation to measure hydrogen partial pressure and concentration in the expansion-tank headspace gas. We measured hydrogen partial pressure in the headspace gas mixture using a palladium-alloy membrane, which is permeable exclusively to hydrogen. The membrane establishes a pure hydrogen gas phase that is in equilibrium with the hydrogen in the gas mixture. We designed and fabricated instrumentation, and demonstrated its effectiveness in measuring hydrogen partial pressures over a range of three orders of magnitude. Our goal is to install this instrument at the Nevada Solar One power plant and to demonstrate its effectiveness in measuring hydrogen levels in the expansion tanks under normal plant operating conditions.

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

Energy Technology Data Exchange (ETDEWEB)

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

2010-10-01

Solar Advisor Model (SAM) is a free software package made available by the National Renewable Energy Laboratory (NREL), Sandia National Laboratory, and the US Department of Energy. SAM contains hourly system performance and economic models for concentrating solar power (CSP) systems, photovoltaic, solar hot-water, and generic fuel-use technologies. Versions of SAM prior to 2010 included only the parabolic trough model based on Excelergy. This model uses top-level empirical performance curves to characterize plant behavior, and thus is limited in predictive capability for new technologies or component configurations. To address this and other functionality challenges, a new trough model; derived from physical first principles was commissioned to supplement the Excelergy-based empirical model. This new 'physical model' approaches the task of characterizing the performance of the whole parabolic trough plant by replacing empirical curve-fit relationships with more detailed calculations where practical. The resulting model matches the annual performance of the SAM empirical model (which has been previously verified with plant data) while maintaining run-times compatible with parametric analysis, adding additional flexibility in modeled system configurations, and providing more detailed performance calculations in the solar field, power block, piping, and storage subsystems.

Adaptive Energy-based Bilinear Control of First-Order 1-D Hyperbolic PDEs: Application to a One-Loop Parabolic Solar Collector Trough

KAUST Repository

Mechhoud, Sarra; Laleg-Kirati, Taous-Meriem

2017-01-01

In this paper, the adaptive bilinear control of a first-order 1-D hyperbolic partial differential equation (PDE) with an unknown time-varying source term is investigated where only boundary measurements are available. By means of boundary injection, the bilinear adaptive law is developed in the Lyapunov approach. It consists of a state observer and an input adaptation law combined with a bilinear control method derived using an energy-like principle. Both global asymptotic practical convergence of the tracking error and input-to-state stability of the system are guaranteed. A potential application of this control strategy is the one-loop solar collector parabolic trough where the solar irradiance is the unknown input (source term) and the flow rate is the control variable. The objective is to drive the boundary temperature at the outlet to track a desired profile. Simulation results are provided to illustrate the performance of the proposed method.

Adaptive Energy-based Bilinear Control of First-Order 1-D Hyperbolic PDEs: Application to a One-Loop Parabolic Solar Collector Trough

KAUST Repository

Mechhoud, Sarra

2017-12-14

In this paper, the adaptive bilinear control of a first-order 1-D hyperbolic partial differential equation (PDE) with an unknown time-varying source term is investigated where only boundary measurements are available. By means of boundary injection, the bilinear adaptive law is developed in the Lyapunov approach. It consists of a state observer and an input adaptation law combined with a bilinear control method derived using an energy-like principle. Both global asymptotic practical convergence of the tracking error and input-to-state stability of the system are guaranteed. A potential application of this control strategy is the one-loop solar collector parabolic trough where the solar irradiance is the unknown input (source term) and the flow rate is the control variable. The objective is to drive the boundary temperature at the outlet to track a desired profile. Simulation results are provided to illustrate the performance of the proposed method.

Prominent reflector beneath around the segmentation boundary between Tonankai-Nankai earthquake area

Science.gov (United States)

Nakanishi, A.; Shimomura, N.; Fujie, G.; Kodaira, S.; Obana, K.; Takahashi, T.; Yamamoto, Y.; Yamashita, M.; Takahashi, N.; Kaneda, Y.; Mochizuki, K.; Kato, A.; Iidaka, T.; Kurashimo, E.; Shinohara, M.; Takeda, T.; Shiomi, K.

2013-12-01

In the Nankai Trough subduction seismogenic zone, the Nankai and Tonankai earthquakes had often occurred simultaneously, and caused a great event. In most cases, first break of such large events of Nankai Trough usually begins from southwest off the Kii Peninsula so far. The idea of split Philippine Sea plate between the Kii Peninsula and the Shikoku Island, which explains seismicity, tectonic background, receiver function image and historical plate motion, was previously suggested. Moreover, between the Kii Peninsula and the Shikoku Island, there is a gap of deep low-frequency events observed in the belt-like zone along the strike of the subducting Philippine Sea plate. In 2010 and 2011, we conducted the large-scale high-resolution wide-angle and reflection (MCS) seismic study, and long-term observation from off Shikoku and Kii Peninsula. Marine active source seismic data have been acquired along grid two-dimensional profiles having the total length of ~800km/year. A three-dimensional seismic tomography using active and passive seismic data observed both land and ocean bottom stations have been also performed. From those data, we found a possible prominent reflector imaged in the offshore side in the Kii channel at the depth of ~18km. The velocity just beneath the reflector cannot be determined due to the lack of ray paths. Based of the amplitude information, we interpret the reflector as the forearc Moho based on the velocity gap (from ~6.4km/s to ~7.4km/s). However, the reflector is shallower than the forearc Moho of other area along the Nankai Trough. Similar reflectors are recognized along other seismic profiles around the Kii channel. In this presentation, we will show the result of structure analysis to understand the peculiar structure including the prominent reflector around the Kii channel. Relation between the structure and the existence of the segmentation of the Nankai megathrust earthquake or seismic gap of the deep low-frequency events will be also

Investigation of solar parabolic trough power plants with and without integrated TES (thermal energy storage) and FBS (fuel backup system) using thermic oil and solar salt

International Nuclear Information System (INIS)

Boukelia, T.E.; Mecibah, M.S.; Kumar, B.N.; Reddy, K.S.

2015-01-01

Thermodynamic, economic and environmental analyses of concentrating solar power plants assist in identifying an effective and viable configuration. In this paper, a 4E (energy-exergy-environmental-economic) comparative study of 8 different configurations of parabolic trough solar thermal power plants with two different working fluids (Therminol VP-1 -oil and molten solar salt), with and without integrated thermal energy storage or/and backup fuel system is presented. The results of the comparative study indicate relevant differences among the 8 configurations. The molten solar salt configuration with integrated thermal energy storage and fossil fuel backup system exhibits the highest overall energy efficiency (18.48%) compared to other configurations. Whereas, the highest overall exergy efficiency (21.77%), capacity factor (38.20%) and annual energy generation (114 GWh) are found for the oil based configuration with integrated thermal energy storage and fossil fuel backup system. The results indicate that the configurations based on molten salt are better in terms of environmental and economical parameters. The configurations with integrated thermal energy storage and fossil fuel backup system are found to be techno-economical, but on the other hand are less environment friendly. A detailed comparison of these plants after optimization must be performed before drawing a final conclusion about the best configuration to be adopted in parabolic trough solar thermal power plant. - Highlights: • 4E comparative study of 8 configurations of PTSTPP with two different fluids. • Comparison of the configurations with and without integrated TES (thermal energy storage) and FBS (fuel backup system). • The overall energy efficiency of the salt plant with TES and FBS is the highest. • The overall exergy efficiency of the oil plant with TES and FBS is the highest. • The salt plants are the best configurations in terms of environ–eco parameters

A finite-volume model of a parabolic trough photovoltaic/thermal collector: Energetic and exergetic analyses

International Nuclear Information System (INIS)

Calise, Francesco; Palombo, Adolfo; Vanoli, Laura

2012-01-01

This paper presents a detailed finite-volume model of a concentrating photovoltaic/thermal (PVT) solar collector. The PVT solar collector consists in a parabolic trough concentrator and a linear triangular receiver. The bottom surfaces of the triangular receiver are equipped with triple-junction cells whereas the top surface is covered by an absorbing surface. The cooling fluid (water) flows inside a channel along the longitudinal direction of the PVT collector. The system was discretized along its axis and, for each slice of the discretized computational domain, mass and energy balances were considered. The model allows one to evaluate both thermodynamic and electrical parameters along the axis of the PVT collector. Then, for each slice of the computational domain, exergy balances were also considered in order to evaluate the corresponding exergy destruction rate and exergetic efficiency. Therefore, the model also calculates the magnitude of the irreversibilities inside the collector and it allows one to detect where these irreversibilities occur. A sensitivity analysis is also performed with the scope to evaluate the effect of the variation of the main design/environmental parameters on the energetic and exergetic performance of the PVT collector. -- Highlights: ► The paper investigates an innovative concentrating photovoltaic thermal solar collector. ► The collector is equipped with triple-junction photovoltaic layers. ► A local exergetic analysis is performed in order to detect sources of irreversibilities. ► Irreversibilities are mainly due to the heat transfer between sun and PVT collector.

The impact of internal longitudinal fins in parabolic trough collectors operating with gases

International Nuclear Information System (INIS)

Bellos, Evangelos; Tzivanidis, Christos; Daniil, Ilias; Antonopoulos, Kimon A.

2017-01-01

Highlights: • In this study, the impact of internal fins in PTC operating with gases is presented. • Air, helium and CO_2 are tested in smooth absorber and with fins of 5–10 mm and 15 mm. • Greater fin length leads to higher thermal efficiency and 10 mm is the optimum length exergetically. • Helium is the best working fluid exergetically, with CO_2 and air to follow. • Up to 290 °C, helium performs better energetically, while CO_2 in higher temperatures. - Abstract: In this study, the use of internal fins in parabolic trough collectors operating with gas working fluids is examined. Air, helium and carbon dioxide are the investigated working fluids, while Eurotrough ET-150 is the examined solar collector. The design and the simulation of this solar collector are performed with the commercial software Solidworks Flow Simulation. The internal fins lead to higher thermal efficiency but also to higher pressure losses; something very important for the solar fields of Concentrated Power Plants. Thus, the collector is examined energetically and exergetically in order to take into account the increase in the useful output with the simultaneous greater need of pumping power. Various fin lengths are examined and finally the fin of 10 mm was proved to be the most appropriate exergetically. In working fluid comparison, helium is the most efficient working fluid exergetically for all the examined cases. In the thermal efficiency comparison, helium performs better up to 290 °C, while carbon dioxide is the best choice in higher temperature levels. Moreover, the optimum mass flow rate for the helium was proved to be 0.03 kg/s and for the other working fluids the value of 0.015 kg/s seems to lead to the most satisfying results.

a numerical analysis of the energy behavior of a parabolic trough ...

African Journals Online (AJOL)

M. Ghodbane

A computer program was developed in Matlab after discretization equations. For the calculation of energy balance was asks these assumptions: The heat transfer fluid is incompressible;. The parabolic shape is symmetrical;. The ambient temperature around the concentrator is uniform;. The effect of the shadow of ...

Modular Trough Power Plant Cycle and Systems Analysis

Energy Technology Data Exchange (ETDEWEB)

Price, H.; Hassani, V.

2002-01-01

This report summarizes an analysis to reduce the cost of power production from modular concentrating solar power plants through a relatively new and exciting concept that merges two mature technologies to produce distributed modular electric power in the range of 500 to 1,500 kWe. These are the organic Rankine cycle (ORC) power plant and the concentrating solar parabolic (CSP) trough technologies that have been developed independent of each other over many years.

Optical, geometric and thermal study for solar parabolic concentrator efficiency improvement under Tunisia environment: A case study

International Nuclear Information System (INIS)

Skouri, Safa; Ben Salah, Mohieddine; Bouadila, Salwa; Balghouthi, Moncef; Ben Nasrallah, Sassi

2013-01-01

Highlights: • Design and construction of solar parabolic concentrator. • Photogrammetry study of SPC. • Slope error and optical efficiency of SPC. • Reflector materials of SPC. • Programmed tracking solar system. - Abstract: Renewable energy generation is becoming more prevalent today. It is relevant to consider that solar concentration technologies contribute to provide a real alternative to the consumption of fossil fuels. The purpose of this work is the characterization of a solar parabolic solar concentrator (SPC) designed, constructed and tested in the Research and Technologies Centre of Energy in Tunisia (CRTEn) in order to improve the performance of the system. Photogrammetry measurement used to analyze the slope errors and to determine hence determining the geometric deformation of the SPC system, which presents an average slope error around 0.0002 and 0.0073 mrad respectively in the center and in the extremities. An optimization of the most performed reflector material has been done by an experimental study of three types of reflectors. A two axes programmed tracking system realized, used and tested in this study. An experimental study is carried out to evaluate the solar parabolic concentrator thermal efficiency after the mechanical and the optical SPC optimization. The thermal energy efficiency varies from 40% to 77%, the concentrating system reaches an average concentration factor around 178

Automatic control of plants of direct steam generation with cylinder-parabolic solar collectors; Control automatico de plantas de generacion directa de vapor con colectores solares cilindro-parabolicos

Energy Technology Data Exchange (ETDEWEB)

Valenzuela Gutierrez, L.

2008-07-01

The main objective of this dissertation has been the contributions to the operation in automatic mode of a new generation of direct steam generation solar plants with parabolic-trough collectors. The dissertation starts introducing the parabolic-trough collectors solar thermal technology for the generation of process steam or steam for a Rankine cycle in the case of power generation generation, which is currently the most developed and commercialized technology. Presently, the parabolic-trough collectors technology is based on the configuration known as heat-exchanger system, based in the use of a heat transfer fluid in the solar field which is heated during the recirculation through the absorber tubes of the solar collectors, transferring later on the that thermal energy to a heat-exchanger for steam generation. Direct steam generation in the absorber tubes has always been shown as an ideal pathway to reduce generation cost by 15% and increase conversion efficiency by 20% (DISS, 1999). (Author)

Experimental Investigation of a Solar Greenhouse Heating System Equipped with a Parabolic Trough Solar Concentrator and a Double-Purpose Flat Plate Solar Collector

Directory of Open Access Journals (Sweden)

M Jafari

2017-10-01

Full Text Available Introduction Greenhouses provide a suitable environment in which all the parameters required for growing the plants can be controlled throughout the year. Greenhouse heating is one of the most important issues in productivity of a greenhouse. In many countries, heating costs in the greenhouses are very high, having almost 60-80% of the total production costs. In recent years, several studies have attempted to reduce the heating costs of the greenhouses by applying more energy efficient equipment and using the renewable energy sources as alternatives or supplementary to the fossil fuels. In the present study a novel solar greenhouse heating system equipped with a parabolic trough solar concentrator (PTC and a flat-plate solar collector has been developed. Therefore, the aim of this paper is to investigate the performance of the proposed heating system at different working conditions. Materials and Methods The presented solar greenhouse heating system was comprised of a parabolic trough solar concentrator (PTC, a heat storage tank, a pump and a flat plate solar collector. The PTC was constructed from a polished stainless steel sheet (as the reflector and a vacuum tube receiver. The PTC was connected to the tank by using insulated tubes and a water pump was utilized to circulate the working fluid trough the PTC and the heat exchanger installed between walls of the tank. The uncovered solar collector was located inside the greenhouse. During the sunshine time, a fraction of the total solar radiation received inside the greenhouse is absorbed by the solar collector. This rises the temperature of the working fluid inside the collector which led to density reduction and natural flow of the fluid. In other words, the collector works as a natural flow flat plate solar collector during the sunshine time. At night, when the greenhouse temperature is lower than tank temperature, the fluid flows in a reverse direction through the solar collector and the

EMC design for actuators in the FAST reflector

Science.gov (United States)

Zhang, Hai-Yan; Wu, Ming-Chang; Yue, You-Ling; Gan, Heng-Qian; Hu, Hao; Huang, Shi-Jie

2018-04-01

An active reflector is one of the three main innovations incorporated in the Five-hundred-meter Aperture Spherical radio Telescope (FAST). The deformation of such a huge spherically shaped reflector into different transient parabolic shapes is achieved by using 2225 hydraulic actuators which change the position of the 2225 nodes through the connected down tied cables. For each different tracking process of the telescope, more than 1/3 of these 2225 actuators must be in operation to tune the parabolic aperture accurately and meet the surface error restriction. This means that some of these actuators are inevitably located within the main beam of the receiver, and Electromagnetic Interference (EMI) from the actuators must be mitigated to ensure the scientific output of the telescope. Based on the threshold level of interference detrimental to radio astronomy described in ITU-R Recommendation RA.769 and EMI measurements, the shielding efficiency (SE) requirement for each actuator is set to be 80 dB in the frequency range from 70 MHz to 3 GHz. Therefore, Electromagnetic Compatibility (EMC) was taken into account in the actuator design by measures such as power line filters, optical fibers, shielding enclosures and other structural measures. In 2015, all the actuators had been installed at the FAST site. Till now, no apparent EMI from the actuators has been detected by the receiver, which demonstrates the effectiveness of these EMC measures.

Design and performance characteristics of solar adsorption refrigeration system using parabolic trough collector: Experimental and statistical optimization technique

International Nuclear Information System (INIS)

Abu-Hamdeh, Nidal H.; Alnefaie, Khaled A.; Almitani, Khalid H.

2013-01-01

Highlights: • The successes of using olive waste/methanol as an adsorbent/adsorbate pair. • The experimental gross cycle coefficient of performance obtained was COP a = 0.75. • Optimization showed expanding adsorbent mass to a certain range increases the COP. • The statistical optimization led to optimum tank volume between 0.2 and 0.3 m 3 . • Increasing the collector area to a certain range increased the COP. - Abstract: The current work demonstrates a developed model of a solar adsorption refrigeration system with specific requirements and specifications. The recent scheme can be employed as a refrigerator and cooler unit suitable for remote areas. The unit runs through a parabolic trough solar collector (PTC) and uses olive waste as adsorbent with methanol as adsorbate. Cooling production, COP (coefficient of performance, and COP a (cycle gross coefficient of performance) were used to assess the system performance. The system’s design optimum parameters in this study were arrived to through statistical and experimental methods. The lowest temperature attained in the refrigerated space was 4 °C and the equivalent ambient temperature was 27 °C. The temperature started to decrease steadily at 20:30 – when the actual cooling started – until it reached 4 °C at 01:30 in the next day when it rose again. The highest COP a obtained was 0.75

Design and manufacture of large lightweight composite reflectors for microwave testing

Science.gov (United States)

Towers, P.

The installation of the largest compact microwave test range constructed to date prompted the design and manufacture of a 250-sq ft parabolic reflector supported by a lightweight, dimensionally stable structure that could be produced at relatively low cost to high tolerances. These tolerances had, moreover, to be maintained during transport and erection in an indoor test range that was remote from the manufacturing site. The dish designed to meet these requirements consisted of an 'egg box' structure with epoxy/glass composite skin-aluminum honeycomb core sandwich construction. Tiles of this same material formed the substrate for a strickled syntactic-filled epoxy resin grout that was subsequently machined to form the silver-coated reflector surface.

Exergy analysis of parabolic trough solar collectors integrated with combined steam and organic Rankine cycles

International Nuclear Information System (INIS)

Al-Sulaiman, Fahad A.

2014-01-01

Highlights: • As the solar irradiation increases, the exergetic efficiency increases. • The R134a combined cycle has best exergetic performance, 26%. • The R600a combined cycle has the lowest exergetic efficiency, 20%. • The main source of exergy destruction is the solar collector. • There is an exergetic improvement potential of 75% in the systems considered. - Abstract: In this paper, detailed exergy analysis of selected thermal power systems driven by parabolic trough solar collectors (PTSCs) is presented. The power is produced using either a steam Rankine cycle (SRC) or a combined cycle, in which the SRC is the topping cycle and an organic Rankine cycle (ORC) is the bottoming cycle. Seven refrigerants for the ORC were examined: R134a, R152a, R290, R407c, R600, R600a, and ammonia. Key exergetic parameters were examined: exergetic efficiency, exergy destruction rate, fuel depletion ratio, irreversibility ratio, and improvement potential. For all the cases considered it was revealed that as the solar irradiation increases, the exergetic efficiency increases. Among the combined cycles examined, the R134a combined cycle demonstrates the best exergetic performance with a maximum exergetic efficiency of 26% followed by the R152a combined cycle with an exergetic efficiency of 25%. Alternatively, the R600a combined cycle has the lowest exergetic efficiency, 20–21%. This study reveals that the main source of exergy destruction is the solar collector where more than 50% of inlet exergy is destructed, or in other words more than 70% of the total destructed exergy. In addition, more than 13% of the inlet exergy is destructed in the evaporator which is equivalent to around 19% of the destructed exergy. Finally, this study reveals that there is an exergetic improvement potential of 75% in the systems considered

Thermodynamic performance assessment of an integrated geothermal powered supercritical regenerative organic Rankine cycle and parabolic trough solar collectors

International Nuclear Information System (INIS)

Cakici, Duygu Melek; Erdogan, Anil; Colpan, Can Ozgur

2017-01-01

In this study, the thermodynamic performance of an integrated geothermal powered supercritical regenerative organic Rankine cycle (ORC) and parabolic trough solar collectors (PTSC) is assessed. A thermal model based on the principles of thermodynamics (mass, energy, and exergy balances) and heat transfer is first developed for the components of this integrated system. This model gives the performance assessment parameters of the system such as the electrical and exergetic efficiencies, total exergy destruction and loss, productivity lack, fuel depletion ratio, and improvement potential rate. To validate this model, the data of an existing geothermal power plant based on a supercritical ORC and literature data for the PTSC are used. After validation, parametric studies are conducted to assess the effect of some of the important design and operating parameters on the performance of the system. As a result of these studies, it is found that the integration of ORC and PTSC systems increases the net power output but decreases the electrical and exergetic efficiencies of the integrated system. It is also shown that R134a is the most suitable working fluid type for this system; and the PTSCs and air cooled condenser are the main sources of the exergy destructions. - Highlights: • A geothermal power plant integrated with PTSC is investigated. • Different approaches for defining the exergetic efficiency are used. • The PTSCs and ACC are the main sources of the exergy destructions. • R134a gives the highest performance for any number of collectors studied.

Experimental investigations into low concentrating line axis solar concentrators for CPV applications

OpenAIRE

Singh, H; Sabry, M; Redpath, DAG

2016-01-01

Solar photovoltaic conversion systems with integrated, low concentration ratio, non-imaging reflective concentrators, could be on south facing building roofs used to generate power at a lower cost than currently available proprietary systems. The experimental investigation presented by this research provides information on the optical and energy conversion characteristics of two geometrically equivalent non-imaging concentrators; a compound parabolic concentrator and a V-trough reflector. The...

High-temperature stable absorber coatings for linear concentrating solar thermal power plants; Hochtemperaturstabile Absorberschichten fuer linear konzentrierende solarthermische Kraftwerke

Energy Technology Data Exchange (ETDEWEB)

Hildebrandt, Christina

2009-03-23

This work describes the development of new absorber coatings for different applications - para-bolic trough and linear Fresnel collectors - and operating conditions - absorber in vacuum or in air. The demand for higher efficiencies of solar thermal power plants using parabolic trough technology results in higher temperatures in the collectors and on the absorber tubes. As heat losses increase strongly with increasing temperatures, the need for a lower emissivity of the absorber coating at constant absorptivity arises. The linear Fresnel application envisions ab-sorber tubes stable in air at high temperatures of about 450 C, which are to date commercially not available. This work comprises the theoretical background, the modeling and the fabrication of absorber tubes including the technology transfer to a production-size inline sputter coater. In annealing tests and accompanying optical measurements, degradation processes have been observed and specified more precisely by material characterization techniques. The simulations provided the capability of different materials used as potential IR-reflector. The highest selectivity can be achieved by applying silver which consequently has been chosen for the application in absorber coatings of the parabolic trough technology. Thin silver films how-ever need to be stabilized when used at high temperatures. Appropriate barrier layers as well as process and layer parameters were identified. A high selectivity was achieved and stability of the absorber coating for 1200 h at 500 C in vacuum has been demonstrated. For the application in air, silver was also analyzed as a potential IR-reflector. Even though the stability could be increased considerably, it nevertheless proved to be insufficient. The main factors influencing stability in a positive way are the use of higher quality polishing, additional barrier layers and adequate process parameters. This knowledge was applied for developing coatings which are stable in air at

Thermodynamic analysis and optimization of an integrated Rankine power cycle and nano-fluid based parabolic trough solar collector

International Nuclear Information System (INIS)

Toghyani, Somayeh; Baniasadi, Ehsan; Afshari, Ebrahim

2016-01-01

Highlights: • The performance of an integrated nano-fluid based solar Rankine cycle is studied. • The effect of solar intensity, ambient temperature, and volume fraction is evaluated. • The concept of Finite Time Thermodynamics is applied. • It is shown that CuO/oil nano-fluid has the best performance from exergy perspective. - Abstract: In this paper, the performance of an integrated Rankine power cycle with parabolic trough solar system and a thermal storage system is simulated based on four different nano-fluids in the solar collector system, namely CuO, SiO_2, TiO_2 and Al_2O_3. The effects of solar intensity, dead state temperature, and volume fraction of different nano-particles on the performance of the integrated cycle are studied using second law of thermodynamics. Also, the genetic algorithm is applied to optimize the net output power of the solar Rankine cycle. The solar thermal energy is stored in a two-tank system to improve the overall performance of the system when sunlight is not available. The concept of Finite Time Thermodynamics is applied for analyzing the performance of the solar collector and thermal energy storage system. This study reveals that by increasing the volume fraction of nano-particles, the exergy efficiency of the system increases. At higher dead state temperatures, the overall exergy efficiency is increased, and higher solar irradiation leads to considerable increase of the output power of the system. It is shown that among the selected nano-fluids, CuO/oil has the best performance from exergy perspective.

Experimental validation of energy parameters in parabolic trough collector with plain absorber and analysis of heat transfer enhancement techniques

Science.gov (United States)

Bilal, F. R.; Arunachala, U. C.; Sandeep, H. M.

2018-01-01

The quantum of heat loss from the receiver of the Parabolic Trough Collector is considerable which results in lower thermal efficiency of the system. Hence heat transfer augmentation is essential which can be attained by various techniques. An analytical model to evaluate the system with bare receiver performance was developed using MATLAB. The experimental validation of the model resulted in less than 5.5% error in exit temperature using both water and thermic oil as heat transfer fluid. Further, heat transfer enhancement techniques were incorporated in the model which included the use of twisted tape inserts, nanofluid, and a combination of both for further enhancement. It was observed that the use of evacuated glass cover in the existing setup would increase the useful heat gain up to 5.3%. Fe3O4/H2O nanofluid showed a maximum enhancement of 56% in the Nusselt number for the volume concentration of 0.6% at highest Reynolds number. Similarly, twisted tape turbulators (with twist ratio of 2) taken alone with water exhibited 59% improvement in Nusselt number. Combining both the heat transfer augmentation techniques at their best values revealed the Nusselt number enhancement up to 87%. It is concluded that, use of twisted tape with water is the best method for heat transfer augmentation since it gives the maximum effective thermal efficiency amongst all for the range of Re considered. The first section in your paper

Techno-Economic Assessment of Heat Transfer Fluid Buffering for Thermal Energy Storage in the Solar Field of Parabolic Trough Solar Thermal Power Plants

Directory of Open Access Journals (Sweden)

Jorge M. Llamas

2017-08-01

Full Text Available Currently, operating parabolic trough (PT solar thermal power plants, either solar-only or with thermal storage block, use the solar field as a heat transfer fluid (HTF thermal storage system to provide extra thermal capacity when it is needed. This is done by circulating heat transfer fluid into the solar field piping in order to create a heat fluid buffer. In the same way, by oversizing the solar field, it can work as an alternative thermal energy storage (TES system to the traditionally applied methods. This paper presents a solar field TES model for a standard solar field from a 50-MWe solar power plant. An oversized solar model is analyzed to increase the capacity storage system (HTF buffering. A mathematical model has been developed and different simulations have been carried out over a cycle of one year with six different solar multiples considered to represent the different oversized solar field configurations. Annual electricity generation and levelized cost of energy (LCOE are calculated to find the solar multiple (SM which makes the highest solar field thermal storage capacity possible within the minimum LCOE.

Thermo-economic analysis and selection of working fluid for solar organic Rankine cycle

International Nuclear Information System (INIS)

Desai, Nishith B.; Bandyopadhyay, Santanu

2016-01-01

Highlights: • Concentrating solar power plant with organic Rankine cycle. • Thermo-economic analysis of solar organic Rankine cycle. • Performance evaluation for different working fluids. • Comparison diagram to select appropriate working fluid. - Graphical Abstract: Display Omitted - Abstract: Organic Rankine cycle (ORC), powered by line-focusing concentrating solar collectors (parabolic trough collector and linear Fresnel reflector), is a promising option for modular scale. ORC based power block, with dry working fluids, offers higher design and part-load efficiencies compared to steam Rankine cycle (SRC) in small-medium scale, with temperature sources up to 400 °C. However, the cost of ORC power block is higher compared to the SRC power block. Similarly, parabolic trough collector (PTC) system has higher optical efficiency and higher cost compared to linear Fresnel reflector (LFR) system. The thermodynamic efficiencies and power block costs also vary with working fluids of the Rankine cycle. In this paper, thermo-economic comparisons of organic Rankine and steam Rankine cycles powered by line-focusing concentrating solar collectors are reported. A simple selection methodology, based on thermo-economic analysis, and a comparison diagram for working fluids of power generating cycles are also proposed. Concentrating solar power plants with any collector technology and any power generating cycle can be compared using the proposed methodology.

Analysis of a linear solar concentrated with stationary reflector and movable center for applications of average temperature; Analisis de un concetrador solar lineal con reflector estacionario y foco movil para aplicaciones de media temperatura

Energy Technology Data Exchange (ETDEWEB)

Pujol, R.; Moia, A.; Martinez, V.

2008-07-01

Three different geometries of a fixed solar mirror concentrator and tracking absorber have been analyzed for medium temperature: FSMC flat mirrors, FSMC parabolic mirrors and only one parabolic mirror OPMSC. These designs can track the sun by moving the receiver around a static reflector in a circular path. A forward ray tracing procedure was implemented by the authors to analyze the influence of the collector parameters on optical efficiency. Various combinations of D/W ratios and geometric concentration ratios C were studied. The analysis showed that as D/W increases the efficiency increases well. Annual efficiencies of a 40% can be reached, in front of 35 % estimated with commercial evacuated tubes at 120 degree centigrade. (Author)

Determination of the optimum design through different funding scenarios for future parabolic trough solar power plant in Algeria

International Nuclear Information System (INIS)

Trad, Ameur; Ait Ali, Mohand Ameziane

2015-01-01

Highlights: • Seven technical design options have been simulated. • The integration of auxiliary heating and TES stabilize electricity generation. • Impact of TES on the technical and economic performance of PTSPP projects. • Different funding scenarios to assess the profitability of CSP plant. • Sensitivity analysis plays an important role in building energy analysis. - Abstract: The purpose of this study is to determine an optimum design for a projected parabolic trough solar power plant (PTSPP) under Algerian climate through different funding scenarios. In this paper, seven different (d1–d7) designs for PTSPP have been developed for the Naâma site. Plant size, technology type, storage capacity, location of the plant, Operation and Maintenance (O and M) costs, replacement costs, fuel consumption, net CO 2 emission, levelized electricity cost, net power generation, specific investment costs and discount rate are the basis factors to determine the optimum sustainable design for PTSPP. The most attractive designs of each base technology were selected as D1, D2 and D3. The preferable design of three funding scenarios was finally selected on economic, financial and sensitivity analysis. It is finally concluded that, under the most favorable economic conditions allowed in this study, design D3 is the most advantageous in terms of benefit to cost ratio: its power output will be 100 MW el with 8 full load hours thermal energy storage. It was also found that for design D3 under funding scenario S2, the project will require an upfront grant of 396 MEUR. This corresponds to around 56% of the total investment cost and the payback period will be approximately 7 years

Studies with Parabolic Parabolic Linear Parabolic (PPLP) momentum function in the LHC

CERN Document Server

Solfaroli Camillocci, Matteo; Timko, Helga; Wenninger, Jorg; CERN. Geneva. ATS Department

2018-01-01

Measurements performed with a Parabolic Parabolic Linear Parabolic (PPLP) momentum function in the LHC. Three attempts have been performed with a pilot bunch and one with nominal bunch (1.1x1011 p/bunch).

Performance analysis of solar parabolic trough collectors driven combined supercritical CO2 and organic Rankine cycle

Directory of Open Access Journals (Sweden)

Harwinder Singh

2018-06-01

Full Text Available In this paper, attempts have been made on the detailed energy and exergy analysis of solar parabolic trough collectors (SPTCs driven combined power plant. The combination of supercritical CO2 (SCO2 cycle and organic Rankine cycle (ORC integrated with SPTCs has been used to produce power, in which SCO2 cycle and ORC are arranged as a topping and bottoming cycle. Five organic working fluids like R134a, R1234yf, R407c, R1234ze, and R245fa were selected for a low temperature bottoming ORC. Five key exergetic parameters such as exergetic efficiency, exergy destruction rate, fuel depletion ratio, irreversibility ratio, and improvement potential were also examined. It was revealed that exergetic and thermal efficiency of all the combined cycles enhances as the direct normal irradiance increases from 0.5 kW/m2 to 0.95 kW/m2. As can be seen, R407c combined cycle has the maximum exergetic as well as thermal efficiency which is around 78.07% at 0.95 kW/m2 and 43.49% at 0.95 kW/m2, respectively. Alternatively, the R134a and R245fa combined cycle yields less promising results with the marginal difference in their performance. As inferred from the study that SCO2 turbine and evaporator has a certain amount of exergy destruction which is around 9.72% and 8.54% of the inlet exergy, and almost 38.10% of the total exergy destruction in case of R407c combined cycle. Moreover, the maximum amount of exergy destructed by the solar collector field which is more than 25% of the solar inlet exergy and around 54% of the total destructed exergy. Finally, this study concludes that R407c combined cycle has a minimum fuel depletion ratio of 0.2583 for a solar collector and possess the highest power output of 3740 kW. Keywords: Supercritical CO2cycle, Organic Rankine cycle, Exergetic performance, SPTCs, Organic fluids

Optical Coating Performance for Heat Reflectors of the JWST-ISIM Electronic Component

Science.gov (United States)

Rashford, Robert A.; Perrygo, Charles M.; Garrison, Matthew B.; White, Bryant K.; Threat, Felix T.; Quijada, Manuel A.; Jeans, James W.; Huber, Frank K.; Bousquet, Robert R.; Shaw, Dave

2011-01-01

A document discusses a thermal radiator design consisting of lightweight composite materials and low-emittance metal coatings for use on the James Webb Space Telescope (JWST) structure. The structure will have a Thermal Subsystem unit to provide passive cooling to the Integrated Science Instrument Module (ISIM) control electronics. The ISIM, in the JWST observatory, is the platform that provides the mounting surfaces for the instrument control electronics. Dissipating the control electronic generated-heat away from JWST is of paramount importance so that the spacecraft s own heat does not interfere with the infrared-light gathering of distant cosmic sources. The need to have lateral control in the emission direction of the IEC (ISIM Electronics Compartment) radiators led to the development of a directional baffle design that uses multiple curved mirrorlike surfaces. This concept started out from the so-called Winston non-imaging optical concentrators that use opposing parabolic reflector surfaces, where each parabola has its focus at the opposite edge of the exit aperture. For this reason they are often known as compound parabolic concentrators or CPCs. This radiator system with the circular section was chosen for the IEC reflectors because it offers two advantages over other designs. The first is that the area of the reflector strips for a given radiator area is less, which results in a lower mass baffle assembly. Secondly, the fraction of energy emitted by the radiator strips and subsequently reflected by the baffle is less. These fewer reflections reduced the amount of energy that is absorbed and eventually re-emitted, typically in a direction outside the design emission range angle. A baffle frame holds the mirrors in position above a radiator panel on the IEC. Together, these will direct the majority of the heat from the IEC above the sunshield away towards empty space.

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

Energy Technology Data Exchange (ETDEWEB)

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

2012-04-01

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

The effect and contribution of wind generated rotation on outlet temperature and heat gain of LS-2 parabolic trough solar collector

Directory of Open Access Journals (Sweden)

Sadaghiyani Omid Karimi

2013-01-01

Full Text Available The Monte Carlo ray tracing method is applied and coupled with finite volume numerical methods to study effect of rotation on outlet temperature and heat gain of LS-2 parabolic trough concentrator (PTC. Based on effect of sunshape, curve of mirror and use of MCRT, heat flux distribution around of inner wall of evacuated tube is calculated. After calculation of heat flux, the geometry of LS-2 Luz collector is created and finite volume method is applied to simulate. The obtained results are compared with Dudley et al test results for irrotational cases to validate these numerical solving models. Consider that, for rotational models ,the solving method separately with K.S. Ball's results. In this work, according to the structure of mentioned collector, we use plug as a flow restriction. In the rotational case studies, the inner wall rotates with different angular speeds. We compare results of rotational collector with irrotational. Also for these two main states, the location of plug changed then outlet temperature and heat gain of collector are studied. The results show that rotation have positive role on heat transfer processing and the rotational plug in bottom half of tube have better effectual than upper half of tube. Also the contribution of rotation is calculated in the all of case studies. Working fluid of these study is one of the oil derivatives namely Syltherm-800. The power of wind can be used to rotate tube of collector.

Reduction of intensity variations on a photovoltaic array with compound parabolic concentrators

Science.gov (United States)

Greenman, P.; Ogallagher, J.; Winston, R.; Costogue, E.

1979-01-01

The reduction of nonuniformities in the intensity distribution of light focused on a photovoltaic array by a compound parabolic concentrator is investigated. The introduction of small distortions into the surfaces of the reflector in order to diffuse the incident collimated light to fill the angular acceptance of the concentrator is calculated by means of ray tracing to decrease the irradiance nonuniformity at the cost of a lowered effective concentration of the concentrator. Measurements of the intensity distribution on a scale test model in terrestrial sunlight with corrugated aluminized mylar reflectors are shown to be in good agreement with the ray tracing results. A two-stage concentrator consisting of a focusing primary and a nonimaging secondary is also shown to result in a fairly uniform intensity distribution except in the case of a 4-deg incidence angle, which may be corrected by the introduction of distortions into one or both concentration stages.

ParaTrough v1.0: Librería en Modelica para Simulación de Plantas Termosolares

Directory of Open Access Journals (Sweden)

Juan A. Romera Cabrerizo

2017-10-01

Full Text Available Resumen: El presente trabajo describe una librería desarrollada en Modelica que utiliza el entorno Dymola 6.1 para modelar y simular plantas termosolares de tecnología de colector cilindro-parabólico. El actual software de modelado y simulación es cada vez más potente gracias a los avances en computación y programación, pudiendo conseguir estimaciones muy precisas del comportamiento de estas plantas térmicas. Como mejora a otras propuestas actuales, la librería ParaTrough se ofrece como una herramienta pública, gratuita bajo licencia Modelica License 2, de código libre, flexible, modular, y por lo tanto fácilmente ampliable y modificable para los requerimientos específicos de cada planta y proceso en particular. En la versión 1.0 contemplada en este artículo, esta librería se puede usar para el modelado y simulación del recurso solar y del sistema de fluido de transferencia calorífica sin cambio de fase. Los modelos han sido validados con datos reales de una planta en operación, Andasol 3, en los términos municipales de Aldeire y La Calahorra (Granada. El objetivo de ParaTrough es poder ser utilizada gratuitamente y de forma amigable por analistas de procesos para uno o varios de los siguientes casos: evaluación del rendimiento, detección de fallos, exploración de nuevos modos de operación y optimización de la planta. Aunque en futuras versiones se puedan añadir otros elementos, esta aportación cubre una nueva área de aplicación específica para el software de Modelica y en su estado actual facilita la operación y mantenimiento de estas plantas. Abstract: This paper describes a Modelica-based library developed to the modeling and simulation of solar thermal plants with parabolic trough collectors. The Dymola 6.1 environment has been used. Unlike other commercial tools, the ParaTrough library is offered as a free open source tool, under Modelica License 2. Its modular code makes it easily extensible and modifiable to

Optical analysis and performance evaluation of a solar parabolic dish concentrator

Directory of Open Access Journals (Sweden)

Pavlović Saša R.

2016-01-01

Full Text Available In this study, the optical design of a solar parabolic dish concentrator is presented. The parabolic dish concentrator consists from 11 curvilinear trapezoidal reflective petals made of polymethyl methacrylate with special reflective coating. The dish diameter is equal to 3.8 m and the theoretical focal point distance is 2.26 m. Numerical simulations are made with the commercial software TracePro from Lambda Research, USA, and the final optimum position between absorber and reflector was calculated to 2.075 m; lower than focus distance. This paper presents results for the optimum position and the optimum diameter of the receiver. The decision for selecting these parameters is based on the calculation of the total flux over the flat and corrugated pipe receiver surface; in its central region and in the peripheral region. The simulation results could be useful reference for designing and optimizing of solar parabolic dish concentrators as for as for CFD analysis, heat transfer and fluid flow analysis in corrugated spiral heat absorbers. [Projekat Ministarstva nauke Republike Srbije, br. III42006: Research and development of energy and environmentally highly effective polygeneration systems based on renewable energy resources i br. III45016: Fabrication and characterization of nanophotonic functional structures in biomedicine and informatics

Reflector Technology Development and System Design for Concentrating Solar Power Technologies

Energy Technology Data Exchange (ETDEWEB)

Adam Schaut

2011-12-30

Alcoa began this program in March of 2008 with the goal of developing and validating an advanced CSP trough design to lower the levelized cost of energy (LCOE) as compared to existing glass based, space-frame trough technology. In addition to showing a pathway to a significant LCOE reduction, Alcoa also desired to create US jobs to support the emerging CSP industry. Alcoa's objective during Phase I: Concept Feasibility was to provide the DOE with a design approach that demonstrates significant overall system cost savings without sacrificing performance. Phase I consisted of two major tasks; reflector surface development and system concept development. Two specific reflective surface technologies were investigated, silver metallized lamination, and thin film deposition both applied on an aluminum substrate. Alcoa prepared samples; performed test validation internally; and provided samples to the NREL for full-spectrum reflectivity measurements. The final objective was to report reflectivity at t = 0 and the latest durability results as of the completion of Phase 1. The target criteria for reflectance and durability were as follows: (1) initial (t = 0), hemispherical reflectance >93%, (2) initial spectral reflectance >90% for 25-mrad reading and >87% for 7-mrad reading, and (3) predicted 20 year durability of less than 5% optical performance drop. While the results of the reflective development activities were promising, Alcoa was unable to down-select on a reflective technology that met the target criteria. Given the progress and potential of both silver film and thin film technologies, Alcoa continued reflector surface development activities in Phase II. The Phase I concept development activities began with acquiring baseline CSP system information from both CSP Services and the DOE. This information was used as the basis to develop conceptual designs through ideation sessions. The concepts were evaluated based on estimated cost and high-level structural

Adoption of nanofluids in low-enthalpy parabolic trough solar collectors: Numerical simulation of the yearly yield

International Nuclear Information System (INIS)

Coccia, Gianluca; Di Nicola, Giovanni; Colla, Laura; Fedele, Laura; Scattolini, Mauro

2016-01-01

Highlights: • Nanofluids could be adopted to increase the efficiency of low-enthalpy PTCs. • We present the results of a numerical simulation performed on a nanofluid-based PTC. • Six water-based nanofluids at different weight concentrations were investigated. • The simulation was validated by experimental tests on two prototypes of PTC. • Results are compared with water: only four concentrations gave better efficiency. - Abstract: Energy demand in the world is continuously increasing and fossil fuels resources must be replaced by renewable resources with lower environmental risk factors, in particular CO_2 emissions. Concentrating solar collectors appear to be very promising for that purpose. Thus, this work presents a numerical analysis for the evaluation of the yearly yield of a low-enthalpy parabolic trough solar collector (PTC). To increase the thermal efficiency of such systems, six water-based nanofluids at different weight concentrations are investigated: Fe_2O_3 (5, 10, 20 wt%), SiO_2 (1, 5, 25 wt%), TiO_2 (1, 10, 20, 35 wt%), ZnO (1, 5, 10 wt%), Al_2O_3 (0.1, 1, 2 wt%), and Au (0.01 wt%). The simulation environment was validated by experimental tests using water as heat transfer fluid, in two prototypes of PTC located in the city of Ancona (central Italy), while the convective heat transfer coefficient of nanofluids was measured through a dedicated apparatus. A typical meteorological year was built to perform the simulation, which presents a time-resolution of one hour. A specific arrangement for the PTC was defined, while different inlet fluid temperatures were considered at a mass flow rate of 0.50 kg/s: 40, 50, 60, 70, and 80 °C. For this last temperature, the variation in flow rate was also studied (at 1 kg/s and 1.5 kg/s). Results show that only Au, TiO_2, ZnO, and Al_2O_3 nanofluids at the lower concentrations, present very small improvements compared to the use of water, while increasing the concentration of nanoparticles no advantage

Comparison of the optics of non-tracking and novel types of tracking solar thermal collectors for process heat applications up to 300{sup o}C

Energy Technology Data Exchange (ETDEWEB)

Grass, C.; Schoelkopf, W.; Staudacher, L.; Hacker, Z. [Bavarian Centre for Applied Energy Research, ZAE Bayern Division 4, Garching (Germany)

2004-03-01

Evacuated CPC (compound parabolic concentrator) collectors with non-tracking reflectors are compared with two novel tracking collectors: a parabolic trough and an evacuated tube collector with integrated tracking reflector. Non-tracking low concentrating CPC collectors are mostly mounted in east-west direction with a latitude dependent slope angle. They are suitable at most for working temperatures up to 200-250 {sup o}C. We present a tracking evacuated tube-collector with a trough-like concentrating mirror. Single-axis tracking of the mirror is realized with a magnetic mechanism. The mirror is mounted inside the evacuated tube and hence protected from environmental influences. One axis tracking in combination with a small acceptance angle allows for higher concentration as compared to non-tracking concentrating collectors. Ray-tracing analysis shows a half acceptance angle of about 5.7{sup o} at geometrical concentration ratio of 3.2. Losses of well constructed evacuated tube collectors (heat conductivity through the manifolds inside the thermally insulated terminating housing are low) are dominated by radiation losses of the absorber. Hence, reducing the absorber size can lead to higher efficiencies at high operating temperature levels. With the presented collector we aim for operating temperatures up to 350 {sup o}C. At temperatures of 300 {sup o}C we expect with anti-reflective coating of the glass tube and a selective absorber coating efficiencies of 0.65. This allows for application in industrial process heat generation, high efficient solar cooling and power generation. A first prototype, equipped with a standard glass tube and a black paint absorber coating, was tested at ZAE Bayern. The optical efficiency was measured to be 0.71. This tube-collector is compared by ray-tracing with non-tracking market available tube-collectors with geometrical concentration ratios up to 1.1 and with a low cost parabolic trough collector of Industrial Solar Technology (IST

Second Generation Novel High Temperature Commercial Receiver & Low Cost High Performance Mirror Collector for Parabolic Solar Trough

Energy Technology Data Exchange (ETDEWEB)

Stettenheim, Joel [Norwich Technologies, White River Junction, VT (United States)

2016-02-29

Norwich Technologies (NT) is developing a disruptively superior solar field for trough concentrating solar power (CSP). Troughs are the leading CSP technology (85% of installed capacity), being highly deployable and similar to photovoltaic (PV) systems for siting. NT has developed the SunTrap receiver, a disruptive alternative to vacuum-tube concentrating solar power (CSP) receivers, a market currently dominated by the Schott PTR-70. The SunTrap receiver will (1) operate at higher temperature (T) by using an insulated, recessed radiation-collection system to overcome the energy losses that plague vacuum-tube receivers at high T, (2) decrease acquisition costs via simpler structure, and (3) dramatically increase reliability by eliminating vacuum. It offers comparable optical efficiency with thermal loss reduction from ≥ 26% (at presently standard T) to ≥ 55% (at high T), lower acquisition costs, and near-zero O&M costs.

Conversion of solar radiation using parabolic mirrors

Directory of Open Access Journals (Sweden)

Jolanta Fieducik

2017-08-01

Full Text Available The use of solar energy is a promising source of renewable energy to cover the energy needs of our society. The aim of the study will be to analyze the possibility of converting solar energy using parabolic reflectors to the heat energy needed to meet the needs of hot water for a family of 4 people. This study presents simulations of the use of solar radiation using radiant concentration systems. The parabolic mirror directs the concentrated beam of sunlight onto a tube located in the focal plane, which is filled with water that under the influence of solar radiation heats up. This article assumes constant mirror geometry and tube cross section, while simulation is performed for different coefficients. For calculations it was assumed that the reflection coefficient of sunlight from the mirror r is variable and an analysis of its effect on the amount of heated liquid is made. The radiation absorption coefficient across the tube surface was determined by a, the thermal surface emissivity coefficient was determined as e and the simulations were performed at variable values for the amount of heated liquid. The calculations and their analysis show that, with appropriately chosen coefficients, it is possible to meet the needs of a 4-person family in warm water using the proposed installation in Poland.

Preliminary experimental study of post-combustion carbon capture integrated with solar thermal collectors

International Nuclear Information System (INIS)

Wang, Fu; Zhao, Jun; Li, Hailong; Deng, Shuai; Yan, Jinyue

2017-01-01

Highlights: • A solar assisted chemical absorption pilot system with two types of collectors (parabolic trough and linear Fresnel reflector) has been constructed. • Performance of two types of solar collectors has been investigated and compared at steady and transient states. • The operations of the pilot system with and without solar assisted have been tested. • The pilot system responds to the temperature of the heat transfer fluid regularly. - Abstract: The amine-based chemical absorption for CO_2 capture normally needs to extract steam from the steam turbine cycle for solvent regeneration. Integrating solar thermal energy enables the reduction of steam extraction and therefore, can reduce the energy penalty caused by CO_2 capture. In this paper, a pilot system of the solar thermal energy assisted chemical absorption was built to investigate the system performance. Two types of solar thermal energy collectors, parabolic trough and linear Fresnel reflector, were tested. It was found that the values of operation parameters can meet the requirements of designed setting parameters, and the solar collectors can provide the thermal energy required by the reboiler, while its contribution was mainly determined by solar irradiation. The solvent regeneration was investigated by varying the heat input. The results show that the response time of the reboiler heat duty is longer than those of the reboiler temperature and desorber pressure. This work provides a better understanding about the overall operation and control of the system.

Operational performance of the development of a 15 kW parabolic trough mid-temperature solar receiver/reactor for hydrogen production

International Nuclear Information System (INIS)

Hong, Hui; Liu, Qibin; Jin, Hongguang

2012-01-01

Highlights: ► A 15 kW solar chemical receiver/reactor for hydrogen production was developed. ► The solar thermochemical efficiency of the receiver/reactor was in the range of 20–28%. ► Hydrogen production exceeding 80% was achieved. ► The research results extend the application of mid-temperature solar thermal energy. -- Abstract: In this paper, we report the operational performance and energy conversion efficiency of a developed 15 kW solar chemical receiver/reactor for hydrogen production. A concentrated solar heat of around 200–300 °C was utilized to provide process heat to drive methanol steam reforming. A modified 15 kW direct-irradiation solar reactor coupled with a linear receiver positioned along the focal line of a one-axis parabolic trough concentrator was used. The experiments were conducted from 200 to 300 °C under a mean solar flux of 300–800 W/m 2 and a reactant feeding rate of 6 kg/h. Reactants were continuously fed, and the attained conversion rate of methanol was more than 70% at 700 W/m 2 . The typical solar thermochemical efficiency of solar thermal energy converted into chemical energy was in the 20–28% range. The overall energy efficiency of input solar power conversion into chemical energy reached up to 17% and may be further increased by improving solar field efficiency. Hydrogen production exceeding 80% was achieved. In addition, preliminary economic evaluation was performed, and methods for further improvement were proposed. This paper proves that solar hydrogen production is feasible by combining solar thermal energy with alternative fuel at around 200–300 °C, which is much lower than the temperature of other solar thermochemical processes. This may offer an economic approach to solar fuel production and extend the application of mid-temperature solar thermal energy.

Evaluation of Surface Slope Irregularity in Linear Parabolic Solar Collectors

Directory of Open Access Journals (Sweden)

F. Francini

2012-01-01

Full Text Available The paper describes a methodology, very simple in its application, for measuring surface irregularities of linear parabolic collectors. This technique was principally developed to be applied in cases where it is difficult to use cumbersome instruments and to facilitate logistic management. The instruments to be employed are a digital camera and a grating. If the reflector surface is defective, the image of the grating, reflected on the solar collector, appears distorted. Analyzing the reflected image, we can obtain the local slope of the defective surface. These profilometric tests are useful to identify and monitor the mirror portions under mechanical stress and to estimate the losses caused by the light rays deflected outside the absorber.

A Combined Optical, Thermal and Electrical Performance Study of a V-Trough PV System—Experimental and Analytical Investigations

Directory of Open Access Journals (Sweden)

Haitham M. Bahaidarah

2015-04-01

Full Text Available The objective of this study was to achieve higher efficiency of a PV system while reducing of the cost of energy generation. Concentration photovoltaics was employed in the present case as it uses low cost reflectors to enhance the efficiency of the PV system and simultaneously reduces the cost of electricity generation. For this purpose a V-trough integrated with the PV system was employed for low concentration photovoltaic (LCPV. Since the electrical output of the concentrating PV system is significantly affected by the temperature of the PV cells, the motivation of the research also included studying the ability to actively cool PV cells to achieve the maximum benefit. The optical, thermal and electrical performance of the V-trough PV system was theoretically modeled and validated with experimental results. Optical modeling of V-trough was carried out to estimate the amount of enhanced absorbed radiation. Due to increase in the absorbed radiation the module temperature was also increased which was predicted by thermal model. Active cooling techniques were studied and the effect of cooling was analyzed on the performance of V-trough PV system. With absorbed radiation and module temperature as input parameters, electrical modeling was carried out and the maximum power was estimated. For the V-trough PV system, experiments were performed for validating the numerical models and very good agreement was found between the two.

Analysis of predicted and measured performance of an integrated compound parabolic concentrator (ICPC)

Energy Technology Data Exchange (ETDEWEB)

Winston, R.; O' Gallagher, J.J.; Muschaweck, J.; Mahoney, A.R.; Dudley, V.

1999-07-01

A variety of configurations of evacuated Integrated Compound Parabolic Concentrator (ICPC) tubes have been under development for many years. A particularly favorable optical design corresponds to the unit concentration limit for a fin CPC solution which is then coupled to a practical, thin, wedge-shaped absorber. Prototype collector modules using tubes with two different fin orientations (horizontal and vertical) have been fabricated and tested. Comprehensive measurements of the optical characteristics of the reflector and absorber have been used together with a detailed ray trace analysis to predict the optical performance characteristics of these designs. The observed performance agrees well with the predicted performance.

A satellite-tracking millimeter-wave reflector antenna system for mobile satellite-tracking

Science.gov (United States)

Densmore, Arthur C.; Jamnejad, Vahraz; Woo, Kenneth E.

1995-03-01

A miniature dual-band two-way mobile satellite tracking antenna system mounted on a movable ground vehicle includes a miniature parabolic reflector dish having an elliptical aperture with major and minor elliptical axes aligned horizontally and vertically, respectively, to maximize azimuthal directionality and minimize elevational directionality to an extent corresponding to expected pitch excursions of the movable ground vehicle. A feed-horn has a back end and an open front end facing the reflector dish and has vertical side walls opening out from the back end to the front end at a lesser horn angle and horizontal top and bottom walls opening out from the back end to the front end at a greater horn angle. An RF circuit couples two different signal bands between the feed-horn and the user. An antenna attitude controller maintains an antenna azimuth direction relative to the satellite by rotating it in azimuth in response to sensed yaw motions of the movable ground vehicle so as to compensate for the yaw motions to within a pointing error angle. The controller sinusoidally dithers the antenna through a small azimuth dither angle greater than the pointing error angle while sensing a signal from the satellite received at the reflector dish, and deduces the pointing angle error from dither-induced fluctuations in the received signal.

Solar Heating of Buildings and Domestic Hot Water. Revision.

Science.gov (United States)

1980-05-01

tracking mechanism and can collect only direct radiation. Figure 2-9(c) shows a compound parabolic mirror collector . The design of the mirrors allow the...linear-trough, fresnel lens tube collector (c compound parabolic mirror IFigurc 2-9. Cirnicntrating coll’ectors lr solar cncrgy. Direct radiation is...the parabolic trough, the linear-trough fresnel lens, and the compound parabolic mirror. -Figure 2-9(a) shows a linear concentrating or parabolic

Trough for piglets

DEFF Research Database (Denmark)

2006-01-01

A trough is disclosed for supplying piglets with mineral supplements in the suckling period. The trough is designed to awaken the piglets' curiosity and thus make them root in the bottom of the trough, where the mineral supplements are dispensed in form of a dry powder mixture, and thus reduce...

Parabolic dune development modes according to shape at the southern fringes of the Hobq Desert, Inner Mongolia, China

Science.gov (United States)

Guan, Chao; Hasi, Eerdun; Zhang, Ping; Tao, Binbin; Liu, Dan; Zhou, Yanguang

2017-10-01

a long and narrow trough between nebkhas by the "funnelling effect". This process forces sand towards lee slopes, which transform from concave (original barchans) into convex, ultimately resulting in the formation of palmate parabolic dunes.

Fiscal 1974 Sunshine Project result report. R and D on solar heat power generation system (R and D on curved reflector light collection system); 1974 nendo taiyonetsu hatsuden system no kenkyu kaihatsu seika hokokusho. kyokumen shuko hoshiki system no kenkyu kaihatsu

Energy Technology Data Exchange (ETDEWEB)

NONE

1975-05-30

This report composed of 6 parts summarizes the fiscal 1974 Sunshine Project research result on the solar heat power generation system with a curved reflector light collection system. Part 1 outlines the research target, research result and research system. Part 2 describes each research item in detail. This part on system and hardware researches is composed of (1) study on 1,000kW system, (2) development of plane/parabolic reflector light collection equipment, (3) development of parabolic reflector light collection equipment, (4) development of selective transparent membrane and selective absorption surface, and (5) study on heat storage equipment and heat exchange equipment. Part 3 describes the future R and D plan for every year focusing the fiscal 1975 R and D plan. Part 4 describes various cooperative activities with other research groups such as various committees related to the Sunshine Project, universities and Electrotechnical Laboratory. Part 5 describes several patents produced during this R and D. Part 6 summarizes the results on this R and D. (NEDO)

A novel portable device to measure the temperature of both the inner and the outer tubes of a parabolic receiver in the field

Science.gov (United States)

Hermoso, J. L. Navarro; Espinosa-Rueda, Guillermo; Martinez, Noelia; Heras, Carlos; Osta, Marta

2016-05-01

The performance of parabolic trough (PT) receiver tubes (RT) has a direct impact on Solar Thermal Energy (STE) plant production. As a result, one major need of operation and maintenance (O&M) in STE plants is to monitor the state of the receiver tube as a key element in the solar field. However the lack of specific devices so far has limited the proper evaluation of operating receiver tubés thermal performance. As a consequence non-accurate approximations have been accepted until now using infrared thermal images of the glass outer tube. In order to fulfill this need, Abengoa has developed a unique portable device for evaluating the thermal performance and vacuum state of parabolic trough receiver tubes placed in the field. The novel device described in this paper, simultaneously provides the temperature of both the inner steel tube and the outer glass tube enabling a check on manufacturers specifications. The on-field evaluation of any receiver tube at any operating temperature has become possible thanks to this new measuring device. The features and usability of this new measurement system as a workable portable device in operating solar fields provide a very useful tool for all companies in the sector contributing to technology progress. The originality of the device, patent pending P201431969, is not limited to the CSP sector, also having scientific significance in the general measuring instruments field. This paper presents the work carried out to develop and validate the device, also detailing its functioning properties and including the excellent results obtained in the laboratory to determine its accuracy and standard deviation. This information was validated with data collected by O&M teams using this instrument in a commercial CSP plant. The relevance of the device has been evidenced by evaluating a wide sample of RT and the results are discussed in this paper. Finally, all the on field collected data is used to demonstrate the high impact that using

Development status of the PDC-1 Parabolic Dish Concentrator

Science.gov (United States)

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

1982-01-01

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

Novel double-stage high-concentrated solar hybrid photovoltaic/thermal (PV/T) collector with nonimaging optics and GaAs solar cells reflector

International Nuclear Information System (INIS)

Abdelhamid, Mahmoud; Widyolar, Bennett K.; Jiang, Lun; Winston, Roland; Yablonovitch, Eli; Scranton, Gregg; Cygan, David; Abbasi, Hamid; Kozlov, Aleksandr

2016-01-01

Highlights: • A novel hybrid concentrating photovoltaic thermal (PV/T) collector is developed. • Thermal component achieves 60× concentration using nonimaging optics. • GaAs solar cells used as spectrally selective mirrors for low energy photons. • Thermal efficiencies of 37% at 365 °C and electrical efficiencies of 8% achieved. • Combined electric efficiency reaches 25% of DNI for system cost of $283.10/m"2". - Abstract: A novel double stage high-concentration hybrid solar photovoltaic thermal (PV/T) collector using nonimaging optics and world record thin film single-junction gallium arsenide (GaAs) solar cells has been developed. We present a detailed design and simulation of the system, experimental setup, prototype, system performance, and economic analysis. The system uses a parabolic trough (primary concentrator) to focus sunlight towards a secondary nonimaging compound parabolic concentrator (CPC) to simultaneously generate electricity from single junction GaAs solar cells, as well as high temperature dispatchable heat. This study is novel in that (a) the solar cells inside the vacuum tube act as spectrally selective mirrors for lower energy photons to maximize the system exergy, and (b) secondary concentrator allows the thermal component to reach a concentration ratio ∼60×, which is significantly higher than conventional PV/T concentration ratios. The maximum outlet temperature reached was 365 °C, and on average the thermal efficiency of the experiment was around 37%. The maximum electrical efficiency was around 8%. The total system electricity generation is around 25% of incoming DNI, by assuming the high temperature stream is used to power a steam turbine. The installed system cost per unit of parabolic trough aperture area is $283.10 per m"2.

Cylinder-type bottom reflector

International Nuclear Information System (INIS)

Elter, C.; Fritz, R.; Kissel, K.F.; Schoening, J.

1982-01-01

Proposal of a bottom reflector for gas-cooled nuclear reactor plants with a pebble bed of spherical fuel elements, where the horizontal forces acting from the core and the bottom reflector upon the side reflector are equally distributed. This is attained by the upper edge of the bottom reflector being placed levelly and by the angle of inclination of the recesses varying. (orig.) [de

Year-round performance assessment of a solar parabolic trough collector under climatic condition of Bhiwani, India: A case study

International Nuclear Information System (INIS)

Kumar, Devander; Kumar, Sudhir

2015-01-01

Highlights: • Year-round performance of SPTC under the various climatic conditions is presented. • A detailed thermo-optical model for PTC system is developed. • A comparison of developed thermal model is done with experimental data of SNL. • Developed model is very helpful and effective tool in analyzing the PTC system. • Enlightens the importance of mini-level SPTC as a promising system to fulfill the energy demands. - Abstract: Solar parabolic trough collector (SPTC) is a well-known solar thermal system applied for solar electric generation. Nowadays, major attention is directed toward improving the performance of solar thermal systems with optimization of solar field production. In this research work, a comprehensive thermo-optical modeling has been proposed to evaluate the performance of a mini-level SPTC considering various heat equilibriums with the environment. Here, receiver wall temperature is considered as the base for modeling. Collector consists of a non-evacuated receiver tube with black paint coating and enveloped with glass cover. Available meteorological data in terms of global and diffuse solar insolations, air temperatures and wind speeds have been used as inputs for performance evaluation of SPTC with horizontal and inclined aperture planes. The validation of the proposed analytical model is justified with existing experimental results and yielded a close agreement. The developed model is successfully applied to a SPTC in order to estimate the through-out year performance characteristics in terms of water temperature rise, heat energy generation, optical and thermal efficiency for the climactic conditions of Bhiwani. The results enlighten that using 0.010 kg/s mass flow rate of water and aperture area of around 1.34 m"2, collector achieved maximum rise in water temperature 11.1 °C and 12.2 °C on horizontal and inclined planes, respectively in the month of April. The uppermost heat energy generation is found to be 2.38 kW h/day in May

Assessment of optical performance of three non-tracking, non-imaging, external compound parabolic concentrators designed for high temperature solar thermal collector units

OpenAIRE

Cisneros, Jesus

2010-01-01

The objective of this thesis is to perform a preliminary optical assessment of the external compound parabolic concentrator (XCPC) component in three concentrating solar thermal units. Each solar thermal unit consists an optical element (the non-imaging concentrating reflector) and a thermal element (the evacuated glass tube solar absorber). The three concentrating solar thermal units discussed in this work are DEWAR 58, a direct flow all-glass dewar, DEWAR 47 an indirect flow ...

Handbook of reflector antennas and feed systems v.3 applications of reflectors

CERN Document Server

Rao, Sudhakar; Sharma, Satish K

2013-01-01

This is the first truly comprehensive and most up-to-date handbook available on modern reflector antennas and feed sources for diversified space and ground applications. There has never been such an all-encompassing reflector handbook in print, and no currently available title offers coverage of such recent research developments. The Handbook consists of three volumes. Volume III focuses on the range of reflector antenna applications, including space, terrestrial, and radar. The intent of this book volume is to provide practical applications and design information on reflector antennas used fo

Real-time dynamic analysis for complete loop of direct steam generation solar trough collector

International Nuclear Information System (INIS)

Guo, Su; Liu, Deyou; Chu, Yinghao; Chen, Xingying; Shen, Bingbing; Xu, Chang; Zhou, Ling; Wang, Pei

2016-01-01

Highlights: • A nonlinear distribution parameter dynamic model has been developed. • Real-time local heat transfer coefficient and friction coefficient are adopted. • The dynamic behavior of the solar trough collector loop are simulated. • High-frequency chattering of outlet fluid flow are analyzed and modeled. • Irradiance disturbance at subcooled water region generates larger influence. - Abstract: Direct steam generation is a potential approach to further reduce the levelized electricity cost of solar trough. Dynamic modeling of the collector loop is essential for operation and control of direct steam generation solar trough. However, the dynamic behavior of fluid based on direct steam generation is complex because of the two-phase flow in the pipeline. In this work, a nonlinear distribution parameter model has been developed to model the dynamic behaviors of direct steam generation parabolic trough collector loops under either full or partial solar irradiance disturbance. Compared with available dynamic model, the proposed model possesses two advantages: (1) real-time local values of heat transfer coefficient and friction resistance coefficient, and (2) considering of the complete loop of collectors, including subcooled water region, two-phase flow region and superheated steam region. The proposed model has shown superior performance, particularly in case of sensitivity study of fluid parameters when the pipe is partially shaded. The proposed model has been validated using experimental data from Solar Thermal Energy Laboratory of University of New South Wales, with an outlet fluid temperature relative error of only 1.91%. The validation results show that: (1) The proposed model successfully outperforms two reference models in predicting the behavior of direct steam generation solar trough. (2) The model theoretically predicts that, during solar irradiance disturbance, the discontinuities of fluid physical property parameters and the moving back and

CNGS Reflector installed

CERN Multimedia

2006-01-01

A major component that will help target the CNGS neutrino beam for its 732km journey through the earth's crust, from CERN to the Gran Sasso laboratory in Italy, has been installed in its final position. The transport of the huge magnetic horn reflector through the CNGS access gallery. A team from CNGS and TS/IC, and the contractors DBS, transported the magnetic horn reflector on 5th December, in a carefully conducted operation that took just under two hours. The reflector is 7m long, 1.6m in diameter and 1.6 tonnes in weight. With only a matter of centimetres to spare on either side, the reflector was transported through the CNGS access gallery, before being installed in the experiment's target chamber. The larger of two magnetic horns, the reflector will help refocus sprays of high energy pions and kaons emitted after a 0.5MW stream of protons from the Super Proton Synchrotron (SPS) strikes nucleons in a graphite target. The horns are toroidal magnetic lenses and work with high pulsed currents: 150 kA f...

Two new designs of parabolic solar collectors

Directory of Open Access Journals (Sweden)

Karimi Sadaghiyani Omid

2014-01-01

Full Text Available In this work, two new compound parabolic trough and dish solar collectors are presented with their working principles. First, the curves of mirrors are defined and the mathematical formulation as one analytical method is used to trace the sun rays and recognize the focus point. As a result of the ray tracing, the distribution of heat flux around the inner wall can be reached. Next, the heat fluxes are calculated versus several absorption coefficients. These heat flux distributions around absorber tube are functions of angle in polar coordinate system. Considering, the achieved heat flux distribution are used as a thermal boundary condition. After that, Finite Volume Methods (FVM are applied for simulation of absorber tube. The validation of solving method is done by comparing with Dudley's results at Sandia National Research Laboratory. Also, in order to have a good comparison between LS-2 and two new designed collectors, some of their parameters are considered equal with together. These parameters are consist of: the aperture area, the measures of tube geometry, the thermal properties of absorber tube, the working fluid, the solar radiation intensity and the mass flow rate of LS-2 collector are applied for simulation of the new presented collectors. After the validation of the used numerical models, this method is applied to simulation of the new designed models. Finally, the outlet results of new designed collector are compared with LS-2 classic collector. Obviously, the obtained results from the comparison show the improving of the new designed parabolic collectors efficiency. In the best case-study, the improving of efficiency are about 10% and 20% for linear and convoluted models respectively.

Economic impact of latent heat thermal energy storage systems within direct steam generating solar thermal power plants with parabolic troughs

International Nuclear Information System (INIS)

Seitz, M.; Johnson, M.; Hübner, S.

2017-01-01

Highlights: • Integration of a latent heat thermal energy storage system into a solar direct steam generation power cycle. • Parametric study of solar field and storage size for determination of the optimal layout. • Evaluation of storage impact on the economic performance of the solar thermal power plant. • Economic comparison of new direct steam generation plant layout with state-of-the-art oil plant layout. - Abstract: One possible way to further reduce levelized costs of electricity of concentrated solar thermal energy is to directly use water/steam as the primary heat transfer fluid within a concentrated collector field. This so-called direct steam generation offers the opportunity of higher operating temperatures and better exergy efficiency. A technical challenge of the direct steam generation technology compared to oil-driven power cycles is a competitive storage technology for heat transfer fluids with a phase change. Latent heat thermal energy storages are suitable for storing heat at a constant temperature and can be used for direct steam generation power plants. The calculation of the economic impact of an economically optimized thermal energy storage system, based on a latent heat thermal energy storage system with phase change material, is the main focus of the presented work. To reach that goal, a thermal energy storage system for a direct steam generation power plant with parabolic troughs in the solar field was thermally designed to determine the boundary conditions. This paper discusses the economic impact of the designed thermal energy storage system based on the levelized costs of electricity results, provided via a wide parametric study. A state-of-the-art power cycle with a primary and a secondary heat transfer fluid and a two-tank thermal energy storage is used as a benchmark technology for electricity generation with solar thermal energy. The benchmark and direct steam generation systems are compared to each other, based respectively

Tailored reflectors for illumination.

Science.gov (United States)

Jenkins, D; Winston, R

1996-04-01

We report on tailored reflector design methods that allow the placement of general illumination patterns onto a target plane. The use of a new integral design method based on the edge-ray principle of nonimaging optics gives much more compact reflector shapes by eliminating the need for a gap between the source and the reflector profile. In addition, the reflectivity of the reflector is incorporated as a design parameter. We show the performance of design for constant irradiance on a distant plane, and we show how a leading-edge-ray method may be used to achieve general illumination patterns on nearby targets.

Coupling in reflector arrays

DEFF Research Database (Denmark)

Appel-Hansen, Jørgen

1968-01-01

In order to reduce the space occupied by a reflector array, it is desirable to arrange the array antennas as close to each other as possible; however, in this case coupling between the array antennas will reduce the reflecting properties of the reflector array. The purpose of the present communic......In order to reduce the space occupied by a reflector array, it is desirable to arrange the array antennas as close to each other as possible; however, in this case coupling between the array antennas will reduce the reflecting properties of the reflector array. The purpose of the present...

Study of the parabolic and elliptic approaches validities for a turbulent co-flowing jet

Directory of Open Access Journals (Sweden)

Mahmoud Houda

2012-01-01

Full Text Available An axisymmetric turbulent jet discharged in a co-flowing stream was studied with the aid of parabolic and elliptic approaches. The simulations were performed with two in-house codes. Detailed comparisons of data show good agreement with the corresponding experiments; and different behaviors of jet dilution were found in initial region at different ranges of velocities ratios. It has been found that the two approaches give practically the same results for the velocities ratios Ru ≤ 1.5. Further from this value, the elliptic approach highlights the appearance of the fall velocity zone and that’s due to the presence of a trough low pressure. This fall velocity has not been detected by the parabolic approach and that’s due to the jet entrainment by the ambient flow. The intensity of this entrainment is directly related to the difference between the primary (jet and the secondary flow (co-flow. In fact, by increasing the velocities ratios Ru, the sucked flux by the outer stream becomes more important; the fall velocity intensifies and changes into a recirculation zone for Ru ≥ 5.

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

Energy Technology Data Exchange (ETDEWEB)

Kelly, B.

2006-07-01

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

Flat Engineered Multichannel Reflectors

Directory of Open Access Journals (Sweden)

V. S. Asadchy

2017-09-01

Full Text Available Recent advances in engineered gradient metasurfaces have enabled unprecedented opportunities for light manipulation using optically thin sheets, such as anomalous refraction, reflection, or focusing of an incident beam. Here, we introduce a concept of multichannel functional metasurfaces, which are able to control incoming and outgoing waves in a number of propagation directions simultaneously. In particular, we reveal a possibility to engineer multichannel reflectors. Under the assumption of reciprocity and energy conservation, we find that there exist three basic functionalities of such reflectors: specular, anomalous, and retroreflections. Multichannel response of a general flat reflector can be described by a combination of these functionalities. To demonstrate the potential of the introduced concept, we design and experimentally test three different multichannel reflectors: three- and five-channel retroreflectors and a three-channel power splitter. Furthermore, by extending the concept to reflectors supporting higher-order Floquet harmonics, we forecast the emergence of other multichannel flat devices, such as isolating mirrors, complex splitters, and multi-functional gratings.

Flat Engineered Multichannel Reflectors

Science.gov (United States)

Asadchy, V. S.; Díaz-Rubio, A.; Tcvetkova, S. N.; Kwon, D.-H.; Elsakka, A.; Albooyeh, M.; Tretyakov, S. A.

2017-07-01

Recent advances in engineered gradient metasurfaces have enabled unprecedented opportunities for light manipulation using optically thin sheets, such as anomalous refraction, reflection, or focusing of an incident beam. Here, we introduce a concept of multichannel functional metasurfaces, which are able to control incoming and outgoing waves in a number of propagation directions simultaneously. In particular, we reveal a possibility to engineer multichannel reflectors. Under the assumption of reciprocity and energy conservation, we find that there exist three basic functionalities of such reflectors: specular, anomalous, and retroreflections. Multichannel response of a general flat reflector can be described by a combination of these functionalities. To demonstrate the potential of the introduced concept, we design and experimentally test three different multichannel reflectors: three- and five-channel retroreflectors and a three-channel power splitter. Furthermore, by extending the concept to reflectors supporting higher-order Floquet harmonics, we forecast the emergence of other multichannel flat devices, such as isolating mirrors, complex splitters, and multi-functional gratings.

Reflectors to Focus Wave Energy

DEFF Research Database (Denmark)

Kramer, Morten; Frigaard, Peter

2005-01-01

Wave Energy Converters (WEC’s) extract wave energy from a limited area, often a single point or line even though the wave energy is generally spread out along the wave crest. By the use of wave reflectors (reflecting walls) the wave energy is effectively focused and increased by approximately 30......-50%. Clearly longer wave reflectors will focus more wave energy than shorter wave reflectors. Thus the draw back is the increased wave forces for the longer wave reflectors. In the paper a procedure for calculating the energy efficiency and the wave forces on the reflectors are described, this by use of a 3D...... boundary element method. The calculations are verified by laboratory experiments and a very good agreement is found. The paper gives estimates of possible power benefit for different wave reflector geometries and optimal geometrical design parameters are specified. On this basis inventors of WEC’s can...

Comparative Experimental Analysis of the Thermal Performance of Evacuated Tube Solar Water Heater Systems With and Without a Mini-Compound Parabolic Concentrating (CPC Reflector(C < 1

Directory of Open Access Journals (Sweden)

Yuehong Su

2012-04-01

Full Text Available Evacuated tube solar water heater systems are widely used in China due to their high thermal efficiency, simple construction requirements, and low manufacturing costs. CPC evacuated tube solar water heaters with a geometrical concentration ratio C of less than one are rare. A comparison of the experimental rig of evacuated tube solar water heater systems with and without a mini-CPC reflector was set up, with a series of experiments done in Hefei (31°53'N, 117°15'E, China. The first and second laws of thermodynamics were used to analyze and contrast their thermal performance. The water in the tank was heated from 26.9 to 55, 65, 75, 85, and 95 °C. Two types of solar water heater systems were used, and the data gathered for two days were compared. The results show that when attaining low temperature water, the evacuated tube solar water heater system without a mini-CPC reflector has higher thermal and exergy efficiencies than the system with a mini-CPC reflector, including the average and immediate values. On the other hand, when attaining high temperature water, the system with a mini-CPC reflector has higher thermal and exergy efficiencies than the other one. The comparison presents the advantages of evacuated tube solar water heater systems with and without a mini-CPC reflector, which can be offered as a reference when choosing which solar water system to use for actual applications.

ON TECTONIC PROBLEMS OF THE OKINAWA TROUGH

Institute of Scientific and Technical Information of China (English)

无

2001-01-01

The Okinawa Trough is a very active tectonic zone at the margin of the Northwest Pacific and is typical of back-arc rifting at the young stage of tectonic evolution. Many scientists from Japan, China, Germany, France, the U.S.A. and Russia have done a lot of geologic and geophysical investigations there. It is well known that the Okinawa Trough is an active back-arc rift with extremely high heat flow, very strong hydrothermal circulation, strong volcanic and magmatic activity, frequent earthquakes, rapid subsidence and rifting, well-developed fault and central graben. But up to now, there are still some important tectonic problems about the Okinawa Trough that require clarification on some aspects such as the type of its crust, its forming time, its tectonic evolution, the distribution of its central grabens, the relationship between its high heat flow and tectonic activity. Based on the data obtained from seismic survey, geomagnetic and gravity measurements, submarine sampling and heat flow measurements in the last 15 years, the author discusses the following tectonic problems about the Okinawa Trough: (1) If the Okinawa Trough develops oceanic crust or not. (2) Is the South Okinawa Trough tectonically more active than the North Okinawa Trough with shallower water and few investigation data on it. (3) The formation time of the Okinawa Trough and its tectonic evolution. The Okinawa Trough has a very thin continental crust. Up to now, there is no evidence of oceanic crust in the Okinawa Trough. The North, Middle and South Okinawa Trough are all very strongly active areas. From 6 Ma B.P., the Okinawa Trough began to form. Since 2 Ma, the Okinawa Trough has been very active.

EVALUATION OF A SOLAR DESALINATION SYSTEM, TYPE CYLINDRICAL PARABOLIC CONCENTRATOR FOR SEA WATER

Directory of Open Access Journals (Sweden)

Carolina Mercado

2015-12-01

Full Text Available In this work, the methodology for the design, construction and commissioning of a solar desalinator, based on a parabolic trough collector and a solar still occurs, is presented. The energy is supplied through the solar collector, which is connected to the distiller. The equipment was set up on the premises of the Universidad Católica del Norte. It is compact, modular, low cost, easy maintenance and long life, with an average production capacity of distilled water of 2.37 l / d, however, it has to be considered that this rate is directly related with weather conditions and sea water flow entering the system, generating an average percentage of 34.04% efficiency. The results obtained with the respective findings, conclusions and recommendations for future projects associated to renewable energy equipment designed analyzed.

Integrated function nonimaging concentrating collector tubes for solar thermal energy

Science.gov (United States)

Winston, R.; Ogallagher, J. J.

1982-09-01

A substantial improvement in optical efficiency over contemporary external reflector evacuated tube collectors has been achieved by integrating the reflector surface into the outer glass envelope. Described are the design fabrication and test results for a prototype collector based on this concept. A comprehensive test program to measure performance and operational characteristics of a 2 sq m panel (45 tubes) has been completed. Efficiencies above 50% relative to beam at 200 C have been repeatedly demonstrated. Both the instantaneous and long term average performance of this totally stationary solar collector are comparable to those for tracking line focus parabolic troughs. The yield, reliability and stability of performance achieved have been excellent. Subcomponent assemblies and fabrication procedures have been used which are expected to be compatible with high volume production. The collector has a wide variety of applications in the 100 to 300 C range including industrial progress heat, air conditioning and Rankine engine operation.

Research Article Special Issue

African Journals Online (AJOL)

pc

2018-03-07

Mar 7, 2018 ... In this research, the solar tracking system using automated circuits for the parabolic trough ... In section 2, prototype design. Then .... parabolic trough concentrating collector are water heater, air heater and heat exchanger.

ON TECTONIC PROBLEMS OF THE OKINAWA TROUGH

Institute of Scientific and Technical Information of China (English)

李乃胜

2001-01-01

The Okinawa Trough is a very active tectonic zone at the margin of the Northwest Pacific and is typical of back-arc rifting at the young stage of tectonic evolution. Many scientists from Japan,China, Germany, France, the U. S.A. and Russia have done a lot of geologic and geophysical investigations there. It is well known that the Okinawa Trough is an active back-arc rift with extremely high heat flow, very strong hydrothermal circulation, strong volcanic and magmatic activity, frequent earthquakes,rapid subsidence and rifting, well-developed fault and central graben. But up to now, there are still some important tectonic problems about the Okinawa Trough that require clarification on some aspects such as the type of its crust, its forming time, its tectonic evolution, the distribution of its central grabens, the relationship between its high heat flow and tectonic activity. Based on the data obtained from seismic sur-vey, geomagnetic and gravity measurements, submarine sampling and heat flow measurements in the last 15 years, the author discusses the following tectonic problems about the Okinawa Trough: (1) If the Okinawa Trough develops oceanic crust or not. (2) Is the South Okinawa Trough tectonically more active than the North Okinawa Trough with shallower water and few investigation data on it. (3) The formation time of the Okinawa Trough and its tectonic evolution. The Okinawa Trough has a very thin continental crust. Up to now, there is no evidence of oceanic crust in the Okinawa Trough. The North, Middle and South Okinawa Trough are all very strongly active areas. From 6 Ma B.P. , the Okinawa Trough began to form. Since 2 Ma, the Okinawa Trough has been very active.

Domestic Material Content in Molten-Salt Concentrating Solar Power Plants

Energy Technology Data Exchange (ETDEWEB)

Turchi, Craig [National Renewable Energy Lab. (NREL), Golden, CO (United States); Kurup, Parthiv [National Renewable Energy Lab. (NREL), Golden, CO (United States); Akar, Sertac [National Renewable Energy Lab. (NREL), Golden, CO (United States); Flores, Francisco [National Renewable Energy Lab. (NREL), Golden, CO (United States)

2015-08-26

This study lists material composition data for two concentrating solar power (CSP) plant designs: a molten-salt power tower and a hypothetical parabolic trough plant, both of which employ a molten salt for the heat transfer fluid (HTF) and thermal storage media. The two designs have equivalent generating and thermal energy storage capacities. The material content of the saltHTF trough plant was approximately 25% lower than a comparably sized conventional oil-HTF parabolic trough plant. The significant reduction in oil, salt, metal, and insulation mass by switching to a salt-HTF design is expected to reduce the capital cost and LCOE for the parabolic trough system.

Theoretical and Experimental Optical Evaluation and Comparison of Symmetric 2D CPC and V-Trough Collector for Photovoltaic Applications

Directory of Open Access Journals (Sweden)

Damasen Ikwaba Paul

2015-01-01

Full Text Available This paper presents theoretical and experimental optical evaluation and comparison of symmetric Compound Parabolic Concentrator (CPC and V-trough collector. For direct optical properties comparison, both concentrators were deliberately designed to have the same geometrical concentration ratio (1.96, aperture area, absorber area, and maximum concentrator length. The theoretical optical evaluation of the CPC and V-trough collector was carried out using a ray-trace technique while the experimental optical efficiency and solar energy flux distributions were analysed using an isolated cell PV module method. Results by simulation analysis showed that for the CPC, the highest optical efficiency was 95% achieved in the interval range of 0° to ±20° whereas the highest outdoor experimental optical efficiency was 94% in the interval range of 0° to ±20°. For the V-tough collector, the highest optical efficiency for simulation and outdoor experiments was about 96% and 93%, respectively, both in the interval range of 0° to ±5°. Simulation results also showed that the CPC and V-trough exhibit higher variation in non-illumination intensity distributions over the PV module surface for larger incidence angles than lower incidence angles. On the other hand, the maximum power output for the cells with concentrators varied depending on the location of the cell in the PV module.

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

Energy Technology Data Exchange (ETDEWEB)

Gawlik, Keith

2013-06-25

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

Structural characteristics around the frontal thrust along the Nankai Trough revealed by bathymetric and seismic reflection survey

Science.gov (United States)

Yamashita, M.; Nakanishi, A.; Moore, G. F.; Kodaira, S.; Nakamura, Y.; Miura, S.; Kaneda, Y.

2016-12-01

Great earthquakes with tsunamis with recurrence intervals of 100-200 years have occurred along the Nankai Trough near central Japan where the Shikoku Basin is subducting with thick sediments on the Philippine Sea plate. To predict the exact height of the tsunami on the coast region generated by these large ruptures, it is important to estimate the vertical deformation that occurs on the seaward end of the rupture area. Recent drilling results have also yielded evidence not only of splay faults that generate tsunamigenic rupture, but also new evidence of tsunamigenic rupture along the frontal thrust at the trench axis in the Nankai Trough. In order to understand the deformation around the frontal thrust at the trench axis, we conducted a dense high-resolution seismic reflection survey with 10-20 km spacing over 1500 km of line length during 2013 and 2014. Clear seismic reflection images of frontal thrusts in the accretionary prism and subducting Shikoku Basin, image deformation along the trench axis between off Muroto Cape and off Ashizuri Cape. The cumulative displacement along the frontal thrust and second thrust are measured from picked distinct reflectors in depth-converted profiles. The average value of cumulative displacement of the frontal thrust is more than 100 m within 2 km depth beneath the seafloor. The location of highest displacement of 300 m displacement agree with the seaward end of slip distribution of the 1946 Nankai event calculated by numerical simulations. We also evaluate the seaward structure for understanding the future rupture distribution. The protothrust zone (PTZ) consisting of many incipient thrusts is identifiable in the portion of trough-fill sediments seaward of the frontal thrust. In order to emphasize the characteristics of frontal thrust and PTZ, we construct the detailed relief image for focusing on the lineated slope of the PTZ at the trough axis. Although our surveys covered a part of Nankai seismogenic zone, it is important to

Two non-tracking solar collectors: Design criteria and performance analysis

International Nuclear Information System (INIS)

Ratismith, Wattana; Inthongkhum, Anusorn; Briggs, John

2014-01-01

Highlights: • A collector module designed to capture solar radiation efficiently is proposed. • Two different compound parabolic trough designs are examined and tested. • A novel design with a flat base trough and vertical absorber operates efficiently in direct and diffuse sunlight. - Abstract: We propose fixed (non-tracking) configurations of solar light collector modules which are designed to operate efficiently throughout the day, i.e. for varying incident angles of direct sunlight, and in conditions of diffuse solar irradiation. We present two trough designs of compound parabolic collector (CPC) type. One, a more conventional double-parabolic trough, has the absorber plate perpendicular to the vertical axis of the trough cross-section. The other, of a new flat-base shape, has the absorber plate parallel. The collectors have two novel features appropriate to non-tracking. The first is a smoothing of the power output over the day by the simple expedient of arranging three troughs tilted at different angles. The second is the original design of the flat-base trough allowing optimal interception of the caustic surfaces of this non-focussing device. By ray-tracing analysis of the different trough shapes and absorber plate orientation, we emphasise the design criteria for achievement of a high intercept factor throughout the day without tracking and demonstrate the superiority of the flat-base collector over the double-parabolic design. In test experiments we show that the high temperatures (≈180 °C) necessary for some industrial process heat applications can be achieved. Also test results of the efficiency of the proposed systems are presented which indicate that the flat-base trough with vertical absorber plate is superior to the double-parabolic trough with horizontal absorber plate

Fixed point of the parabolic renormalization operator

CERN Document Server

Lanford III, Oscar E

2014-01-01

This monograph grew out of the authors' efforts to provide a natural geometric description for the class of maps invariant under parabolic renormalization and for the Inou-Shishikura fixed point itself as well as to carry out a computer-assisted study of the parabolic renormalization operator. It introduces a renormalization-invariant class of analytic maps with a maximal domain of analyticity and rigid covering properties and presents a numerical scheme for computing parabolic renormalization of a germ, which is used to compute the Inou-Shishikura renormalization fixed point.   Inside, readers will find a detailed introduction into the theory of parabolic bifurcation,  Fatou coordinates, Écalle-Voronin conjugacy invariants of parabolic germs, and the definition and basic properties of parabolic renormalization.   The systematic view of parabolic renormalization developed in the book and the numerical approach to its study will be interesting to both experts in the field as well as graduate students wishi...

Dynamics of large reflectors - Aerospatiale concepts

Science.gov (United States)

Flechais, A.; Picard, P.; Dauviau, C.; Truchi, C.

1992-08-01

An overview is presented of studies performed under an ESTEC contract and aimed at the identification of critical development areas of unfurlable reflectors and at the analysis of the dynamic interactions between reflectors and hosting spacecraft, in particular with respect to the design of the AOCS and antenna pointing mechanism (APM). Research and development performed by Aerospatiale since 1983 in the field of unfurlable mesh reflectors and supported by CNES are summarized. An analysis covering both the deployment phase and the deployed configuration is presented. The capabilities of classical AOCS and APM control laws for large reflectors are evaluated via simulations. It is shown that the baseline reflector under consideration is compatible with the PSDE mission and classical AOCS and APM control law designs.

On parabolic external maps

DEFF Research Database (Denmark)

Lomonaco, Luna; Petersen, Carsten Lunde; Shen, Weixiao

2017-01-01

We prove that any C1+BV degree d ≥ 2 circle covering h having all periodic orbits weakly expanding, is conjugate by a C1+BV diffeomorphism to a metrically expanding map. We use this to connect the space of parabolic external maps (coming from the theory of parabolic-like maps) to metrically expan...

241-AZ-101 pump removal trough analysis

International Nuclear Information System (INIS)

Coverdell, B.L.

1995-01-01

As part of the current Hanford mission of environmental cleanup, various long length equipment must be removed from highly radioactive waste tanks. The removal of equipment will utilize portions of the Equipment Removal System for Project W320 (ERS-W320), specifically the 50 ton hydraulic trailer system. Because the ERS-W320 system was designed to accommodate much heavier equipment it is adequate to support the dead weight of the trough, carriage and related equipment for 241AZ101 pump removal project. However, the ERS-W320 components when combined with the trough and its' related components must also be analyzed for overturning due to wind loads. Two troughs were designed, one for the 20 in. diameter carriage and one for the 36 in. diameter carriage. A proposed 52 in. trough was not designed and, therefore is not included in this document. In order to fit in the ERS-W320 strongback the troughs were design with the same widths. Structurally, the only difference between the two troughs is that more material was removed from the stiffener plates on the 36 in trough. The reduction in stiffener plate material reduces the allowable load. Therefore, only the 36 in. trough was analyzed

Early to middle Jurassic salt in Baltimore Canyon trough

Science.gov (United States)

McKinney, B. Ann; Lee, Myung W.; Agena, Warren F.; Poag, C. Wylie

2005-01-01

A pervasive, moderately deep (5-6 s two-way traveltime), high-amplitude reflection is traced on multichannel seismic sections over an approximately 7500 km² area of Baltimore Canyon Trough. The layer associated with the reflection is about 25 km wide, about 60 m thick in the center, and thins monotonically laterally, though asymmetrically, at the edges. Geophysical characteristics are compatible with an interpretation of this negative-polarity reflector as a salt lens deposited on the top of a synrift evaporite sequence. However, alternative interpretations of the layer as gas-saturated sediments, an overpressured shale, or a weathered igneous intrusion are also worthy of consideration.Geophysical analyses were made on three wavelet- and true-amplitude processed multichannel seismic dip lines. The lens-shaped layer demarked by the reflection has a velocity of 4.4 km/s; the lens lies within strata having velocities of 5.3 to 5.7 km/s. A trough marking the onset of the lens has an amplitude that is 10 to 20 db greater than reflections from the encasing layers and an apparent reflection coefficient of -0.24. Using amplitude versus offset analysis methods, we determined that observed reflection coefficients, though variable, decrease consistently with respect to increasing offset. Linear inversion yields a low density, about 2.2 g/cc. Integration of one of the true-amplitude-processed lines and one-dimensional modeling of the layer provide data on the impedance contrast and interference patterns that further reinforce the salt lens interpretation.The thin, horizontal salt lens was probably deposited or precipitated during the Jurassic in a shallow, narrow (peripheral) rift basin, as rifting progressed down the North Atlantic margin. Unlike thicker deposits in other areas that deformed and flowed, often into diapir structures, this thin lens has remained relatively undisturbed since deposition.

Handbook of reflector antennas and feed systems v.1 theory and design of reflectors

CERN Document Server

Sharma, Satish K; Shafai, Lotfollah

2013-01-01

This is the first truly comprehensive and most up-to-date handbook available on modern reflector antennas and feed sources for diversified space and ground applications. There has never been such an all-encompassing reflector handbook in print, and no currently available title offers coverage of such recent research developments. The Handbook consists of three volumes. Volume I provides a unique combination of theoretical underpinnings with design considerations and techniques. The need for knowledge in reflector antennas has grown steadily over the last two decades due to increased use in spa

Gamma Bang Time/Reaction History Diagnostics for the National Ignition Facility (NIF) Using 900 Off-axis Parabolic Mirrors

International Nuclear Information System (INIS)

H.W. Herrmann; R.M. Malone; W. Stoeffl; J.M. Mack; C.S. Young

2008-01-01

Gas Cherenkov detectors (GCD) have been used to convert fusion gamma into photons to achieve gamma bang time (GBT) and reaction history measurements. The GCD designed for Omega used Cassegrain reflector optics in order to fit inside a ten-inch manipulator. A novel design for the National Ignition Facility (NIF) using 90 o Off-Axis Parabolic (OAP) mirrors will increase light collection efficiency from fusion gammas and achieve minimum time dispersion. The broadband Cherenkov light (from 200 to 800 nm) is relayed into a high-speed detector using three parabolic mirrors. Because light is collected from many source planes throughout the CO2 gas volume, the detector is positioned at the stop position rather than an image position. The stop diameter and its position are independent of the light-generation location along the gas cell. The current design collects light from a 100-mm diameter by 500-mm-long gas volume. Optical ray tracings demonstrate how light can be collected from different angled trajectories of the Compton electrons as they fly through the CO2 gas volume. A cluster of four channels will allow for increased dynamic range as well as different gamma energy threshold sensitivities

Gamma bang time/reaction history diagnostics for the National Ignition Facility using 90 degrees off-axis parabolic mirrors.

Science.gov (United States)

Malone, R M; Herrmann, H W; Stoeffl, W; Mack, J M; Young, C S

2008-10-01

Gas Cherenkov detectors (GCDs) have been used to convert fusion gamma into photons to achieve gamma bang time and reaction history measurements. The GCDs designed for OMEGA used Cassegrain reflector optics in order to fit inside a 10 in. manipulator. A novel design for the National Ignition Facility using 90 degrees off-axis parabolic mirrors will increase light collection efficiency from fusion gammas and achieve minimum time dispersion. The broadband Cherenkov light (from 200 to 800 nm) is relayed into a high-speed detector using three parabolic mirrors. Because light is collected from many source planes throughout the CO(2) gas volume, the detector is positioned at the stop position rather than at an image position. The stop diameter and its position are independent of the light-generation location along the gas cell. The current design collects light from a 100 mm diameter by 500 mm long gas volume. Optical ray tracings demonstrate how light can be collected from different angled trajectories of the Compton electrons as they fly through the CO(2) gas volume. A cluster of four channels will allow for increased dynamic range as well as for different gamma energy threshold sensitivities.

PERFORMANCE CHARACTERISTICS OF PARABOLIC SOLAR COLLECTOR WATER HEATER SYSTEM FITTED WITH NAIL TWISTED TAPES ABSORBER

Directory of Open Access Journals (Sweden)

K. SYED JAFAR

2017-03-01

Full Text Available In this paper, the experimental heat transfer, friction loss and thermal performance data for water flowing through the absorber tube fitted with two different twisted tape configurations in parabolic trough collector (PTC are presented. In the present work, a relative experimental study is carried out to investigate the performance of a PTC influenced by heat transfer through fluidabsorber wall mixing mechanism. The major findings of this experiment show that heat transport enhancement in the nail twisted tape collector perform significantly better than plain twisted tapes and also show that the smallest twisted tape ratio enhances the system performance remarkably maximizing the collector efficiency. The results suggest that the twisted tape and nail twisted tape would be a better option for high thermal energy collection in laminar region of the PTC system.

Fabrication of trough-shaped solar collectors

Science.gov (United States)

Schertz, William W.

1978-01-01

There is provided a radiant energy concentration and collection device formed of a one-piece thin-walled plastic substrate including a plurality of nonimaging troughs with certain metallized surfaces of the substrate serving as reflective side walls for each trough. The one-piece plastic substrate is provided with a seating surface at the bottom of each trough which conforms to the shape of an energy receiver to be seated therein.

Controllability and stabilization of parabolic equations

CERN Document Server

Barbu, Viorel

2018-01-01

This monograph presents controllability and stabilization methods in control theory that solve parabolic boundary value problems. Starting from foundational questions on Carleman inequalities for linear parabolic equations, the author addresses the controllability of parabolic equations on a variety of domains and the spectral decomposition technique for representing them. This method is, in fact, designed for use in a wider class of parabolic systems that include the heat and diffusion equations. Later chapters develop another process that employs stabilizing feedback controllers with a finite number of unstable modes, with special attention given to its use in the boundary stabilization of Navier–Stokes equations for the motion of viscous fluid. In turn, these applied methods are used to explore related topics like the exact controllability of stochastic parabolic equations with linear multiplicative noise. Intended for graduate students and researchers working on control problems involving nonlinear diff...

Optimization of Surrounding Reflector Material for Hyb-WT

International Nuclear Information System (INIS)

Tariq Siddique, M.; Hong, Song Hee; Kim, Myung Hyun

2013-01-01

The choice of reflector material is crucial for fusion and hybrid reactors as it was for the fission reactors. Multiple reflector materials were studied for pure fusion blanket design. The purpose of reflector in fusion blanket is to enhance the tritium breeding ratio (TBR). In fusion fission hybrid blanket the roll of reflector is slightly changed as it include the fission core and the performance of fission core also needs to be optimized and evaluated with the choice of reflector material, along with the enhancement of TBR. The performance parameters of Hyb-WT are significantly influenced by the choice of reflector material. TiC is best for TRU transmutation, TBR and reduced the neutron wall loading and graphite is best for FP transmutation. Strategy of multi reflector materials gives the best TRU and FP transmutation performance and also enhanced TBR with reduced neutron wall loading and it is a better choice for Hyb-WT reflector. The neutron flux is primarily dominated by the fission neutrons

Self-accelerating parabolic cylinder waves in 1-D

Energy Technology Data Exchange (ETDEWEB)

Yuce, C., E-mail: cyuce@anadolu.edu.tr

2016-11-25

Highlights: • We find a new class of self-accelerating waves. • We show that parabolic cylinder waves self-accelerates in a parabolic potential. • We discuss that truncated parabolic cylinder waves propagates large distance without almost being non-diffracted in free space. - Abstract: We introduce a new self-accelerating wave packet solution of the Schrodinger equation in one dimension. We obtain an exact analytical parabolic cylinder wave for the inverted harmonic potential. We show that truncated parabolic cylinder waves exhibits their accelerating feature.

WWER radial reflector modeling by diffusion codes

International Nuclear Information System (INIS)

Petkov, P. T.; Mittag, S.

2005-01-01

The two commonly used approaches to describe the WWER radial reflectors in diffusion codes, by albedo on the core-reflector boundary and by a ring of diffusive assembly size nodes, are discussed. The advantages and disadvantages of the first approach are presented first, then the Koebke's equivalence theory is outlined and its implementation for the WWER radial reflectors is discussed. Results for the WWER-1000 reactor are presented. Then the boundary conditions on the outer reflector boundary are discussed. The possibility to divide the library into fuel assembly and reflector parts and to generate each library by a separate code package is discussed. Finally, the homogenization errors for rodded assemblies are presented and discussed (Author)

Design of optically stable image reflector system.

Science.gov (United States)

Tsai, Chung-Yu

2013-08-01

The design of a partially optically stable (POS) reflector system, in which the exit ray direction and image pose are unchanged as the reflector system rotates about a specific directional vector, was presented in an earlier study by the current group [Appl. Phys. B100, 883-890 (2010)]. The present study further proposes an optically stable image (OSI) reflector system, in which not only is the optical stability property of the POS system retained, but the image position and total ray path length are also fixed. An analytical method is proposed for the design of OSI reflector systems comprising multiple reflectors. The validity of the proposed approach is demonstrated by means of two illustrative examples.

16 CFR 1512.16 - Requirements for reflectors.

Science.gov (United States)

2010-01-01

... 1512.16 Commercial Practices CONSUMER PRODUCT SAFETY COMMISSION FEDERAL HAZARDOUS SUBSTANCES ACT... vehicle headlamps. The use of reflector combinations off the center plane of the bicycle (defined in...) Front reflector. The reflector or mount shall not contact the ground plane when the bicycle is resting...

Pyramidal-Reflector Solar Heater

Science.gov (United States)

1982-01-01

Motor-driven reflector compensates for seasonal changes in Sun's altitude. System has flat-plate absorbers mounted on north side of attic interior. Skylight window on south-facing roof admits Sunlight into attic, lined with mirrors that reflect light to absorbers. Reflectors are inner surfaces of a pyramid lying on its side with window at its base and absorber plates in a cross-sectional plane near its apex.

Lamp with a truncated reflector cup

Science.gov (United States)

Li, Ming; Allen, Steven C.; Bazydola, Sarah; Ghiu, Camil-Daniel

2013-10-15

A lamp assembly, and method for making same. The lamp assembly includes first and second truncated reflector cups. The lamp assembly also includes at least one base plate disposed between the first and second truncated reflector cups, and a light engine disposed on a top surface of the at least one base plate. The light engine is configured to emit light to be reflected by one of the first and second truncated reflector cups.

A parabolic model for dimple potentials

International Nuclear Information System (INIS)

Aydin, Melike Cibik; Uncu, Haydar; Deniz, Coskun

2013-01-01

We study the truncated parabolic function and demonstrate that it is a representation of the Dirac δ function. We also show that the truncated parabolic function, used as a potential in the Schrödinger equation, has the same bound state spectrum, tunneling and reflection amplitudes as the Dirac δ potential, as the width of the parabola approximates to zero. Dirac δ potential is used to model dimple potentials which are utilized to increase the phase-space density of a Bose–Einstein condensate in a harmonic trap. We show that a harmonic trap with a δ function at the origin is a limiting case of the harmonic trap with a symmetric truncated parabolic potential around the origin. Hence, the truncated parabolic is a better candidate for modeling the dimple potentials. (paper)

Apparatus including concave reflectors and a line of optical fibers

International Nuclear Information System (INIS)

Dolan, J.T.

1992-01-01

This patent describes an apparatus including a radiation source which emits in a multiplicity of directions for focusing radiation on an object which may receive radiation within a certain solid angle. It comprises a first reflector and a second reflector, the first reflector being elliptical in cross section and having a first focus and a second focus, the second reflector being circular in cross section and having a center, and a radius equal to the distance between the second reflector and the first focus, the first reflector and the second reflector being arranged so that a concave reflecting surface of the first reflector faces a concave reflecting surface of the second reflector, and so arranged that the first focus of the first reflector corresponds to the center of the second reflector, the radiation source being an elongated discharge bulb, the object being a group of two or more optical fibers defining at least one line of optical fibers which are located at the second focus of the first reflector

Non-local quasi-linear parabolic equations

International Nuclear Information System (INIS)

Amann, H

2005-01-01

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

Simulation of reflecting surface deviations of centimeter-band parabolic space radiotelescope (SRT) with the large-size mirror

Science.gov (United States)

Kotik, A.; Usyukin, V.; Vinogradov, I.; Arkhipov, M.

2017-11-01

he realization of astrophysical researches requires the development of high-sensitive centimeterband parabolic space radiotelescopes (SRT) with the large-size mirrors. Constructively such SRT with the mirror size more than 10 m can be realized as deployable rigid structures. Mesh-structures of such size do not provide the reflector reflecting surface accuracy which is necessary for the centimeter band observations. Now such telescope with the 10 m diameter mirror is developed in Russia in the frame of "SPECTR - R" program. External dimensions of the telescope is more than the size of existing thermo-vacuum chambers used to prove SRT reflecting surface accuracy parameters under the action of space environment factors. That's why the numerical simulation turns out to be the basis required to accept the taken designs. Such modeling should be based on experimental working of the basic constructive materials and elements of the future reflector. In the article computational modeling of reflecting surface deviations of a centimeter-band of a large-sized deployable space reflector at a stage of his orbital functioning is considered. The analysis of the factors that determines the deviations - both determined (temperatures fields) and not-determined (telescope manufacturing and installation faults; the deformations caused by features of composite materials behavior in space) is carried out. The finite-element model and complex of methods are developed. They allow to carry out computational modeling of reflecting surface deviations caused by influence of all factors and to take into account the deviations correction by space vehicle orientation system. The results of modeling for two modes of functioning (orientation at the Sun) SRT are presented.

Gradient-type methods in inverse parabolic problems

International Nuclear Information System (INIS)

Kabanikhin, Sergey; Penenko, Aleksey

2008-01-01

This article is devoted to gradient-based methods for inverse parabolic problems. In the first part, we present a priori convergence theorems based on the conditional stability estimates for linear inverse problems. These theorems are applied to backwards parabolic problem and sideways parabolic problem. The convergence conditions obtained coincide with sourcewise representability in the self-adjoint backwards parabolic case but they differ in the sideways case. In the second part, a variational approach is formulated for a coefficient identification problem. Using adjoint equations, a formal gradient of an objective functional is constructed. A numerical test illustrates the performance of conjugate gradient algorithm with the formal gradient.

Reflector modelization for neutronic diffusion and parameters identification

International Nuclear Information System (INIS)

Argaud, J.P.

1993-04-01

Physical parameters of neutronic diffusion equations can be adjusted to decrease calculations-measurements errors. The reflector being always difficult to modelize, we choose to elaborate a new reflector model and to use the parameters of this model as adjustment coefficients in the identification procedure. Using theoretical results, and also the physical behaviour of neutronic flux solutions, the reflector model consists then in its replacement by boundary conditions for the diffusion equations on the core only. This theoretical result of non-local operator relations leads then to some discrete approximations by taking into account the multiscaled behaviour, on the core-reflector interface, of neutronic diffusion solutions. The resulting model of this approach is then compared with previous reflector modelizations, and first results indicate that this new model gives the same representation of reflector for the core than previous. (author). 12 refs

Reflector-moderated critical assemblies

International Nuclear Information System (INIS)

Paxton, H.C.; Jarvis, G.A.; Byers, C.C.

1975-07-01

Experiments with reflector-moderated critical assemblies were part of the Rover Program at the Los Alamos Scientific Laboratory (LASL). These assemblies were characterized by thick D 2 O or beryllium reflectors surrounding large cavities that contained highly enriched uranium at low average densities. Because interest in this type of system has been revived by LASL Plasma Cavity Assembly studies, more detailed descriptions of the early assemblies than had been available in the unclassified literature are provided. (U.S.)

Movements of the mid-latitude ionospheric trough

International Nuclear Information System (INIS)

Rodger, A.S.; Pinnock, M.

1982-01-01

A new method for monitoring the position and movement of large ionospheric structures is described. The technique uses data from an ionosonde nominally operating at vertical incidence, but relies on there being present a significant gradient in electron concentration. The position and dynamics of the poleward edge of the mid-latitude trough over Halley Bay, Antarctica (L = 4.2) is investigated using this method. Analyses show that the trough moves rapidly equatorward over Halley Bay in the early evening hours, during geomagnetically active periods. For magnetically quiet periods, the trough is not observed till after midnight, when its equatorward motion is comparatively slow. These results showed marked differences from those predicted from published empirical relationships describing variations in trough position with time, particularly before midnight. Changes in the position of the plasma pause with time, determined from two theoretical models and from observations are compared with these results for the trough. Also, one case study is presented in which there is determination of the positions of both the trough and the plasmapause over a 7 h period. Similarities and differences in their relative positions and movements of the two features are identified and their possible causes are briefly discussed. (author)

The role of meltwater in high-latitude trough-mouth fan development : the Disko Trough-Mouth Fan, West Greenland.

OpenAIRE

Cofaigh, Colm Ó.; Hogan, Kelly A.; Jennings, Anne E.; Callard, S. Louise; Dowdeswell, Julian A.; Noormets, Riko; Evans, Jeff

2018-01-01

The Disko Trough-Mouth Fan (TMF) is a major submarine sediment fan located along the central west Greenland continental margin offshore of Disko Trough. The location of the TMF at the mouth of a prominent cross-shelf trough indicates that it is a product of repeated glacigenic sediment delivery from former fast-flowing outlets of the Greenland Ice Sheet, including an ancestral Jakobshavn Isbrae, which expanded to the shelf edge during successive glacial cycles. This study focuses on the upper...

Reflector construction by sound path curves - A method of manual reflector evaluation in the field

International Nuclear Information System (INIS)

Siciliano, F.; Heumuller, R.

1985-01-01

In order to describe the time-of-flight behavior of various reflectors we have set up models and derived from them analytical and graphic approaches to reflector reconstruction. In the course of this work, maximum achievable accuracy and possible simplifications were investigated. The aim of the time-of-flight reconstruction method is to determine the points of a reflector on the basis of a sound path function (sound path as the function of the probe index position). This method can only be used on materials which are isotropic in terms of sound velocity since the method relies on time of flight being converted into sound path. This paper deals only with two-dimensional reconstruction, in other words all statements relate to the plane of incidence. The method is based on the fact that the geometrical location of the points equidistant from a certain probe index position is a circle. If circles with radiuses equal to the associated sound path are drawn for various search unit positions the points of intersection of the circles are the desired reflector points

Flexible-Robotic Reflector for Aerospace Applications

Directory of Open Access Journals (Sweden)

Nir Shvalb

2015-01-01

Full Text Available Existing dish based antennas tend to have geometric morphologic distortion in the surface due to drastic thermal changes common in the space environment. In this paper we present a new concept for a dynamic antenna specially designed for communication satellites. The suggested flexible-robotic antenna is based on a dual-reflector structure, where the subreflector has a complex surface shaping robotic mechanism allowing it to fix most of the morphologic errors in the main reflector. We have implemented a set of searching algorithms allowing the hyper redundant robotic subreflector to adapt its surface to the morphologic distortions in the main reflector. The suggested new antenna was constructed and tested in an RF room in which it was able to fix the loss caused by distortion in the main reflector to the original gain in less than an hour.

The parabolic equation method for outdoor sound propagation

DEFF Research Database (Denmark)

Arranz, Marta Galindo

The parabolic equation method is a versatile tool for outdoor sound propagation. The present study has focused on the Cranck-Nicolson type Parabolic Equation method (CNPE). Three different applications of the CNPE method have been investigated. The first two applications study variations of the g......The parabolic equation method is a versatile tool for outdoor sound propagation. The present study has focused on the Cranck-Nicolson type Parabolic Equation method (CNPE). Three different applications of the CNPE method have been investigated. The first two applications study variations...

Research of flaw assessment methods for beryllium reflector elements

International Nuclear Information System (INIS)

Shibata, Akira; Ito, Masayasu; Takemoto, Noriyuki; Tanimoto, Masataka; Tsuchiya, Kunihiko; Nakatsuka, Masafumi; Ohara, Hiroshi; Kodama, Mitsuhiro

2012-02-01

Reflector elements made from metal beryllium is widely used as neutron reflectors to increase neutron flux in test reactors. When beryllium reflector elements are irradiated by neutron, bending of reflector elements caused by swelling occurs, and beryllium reflector elements must be replaced in several years. In this report, literature search and investigation for non-destructive inspection of Beryllium and experiments for Preliminary inspection to establish post irradiation examination method for research of characteristics of metal beryllium under neutron irradiation were reported. (author)

Optimized reflectors for non-tracking solar collectors with tubular absorbers

Energy Technology Data Exchange (ETDEWEB)

Muschaweck, Julius [Optics and Energy Consulting, Munich (Germany); Spirkl, Wolfgang [Ludwig-Maximilians Univ., Sektion Physik, Munich (Germany); Timinger, Andreas [Optics and Energy Consulting, Munich (Germany); ZAE Bayern, Solar Thermal and Biomass Dept., Munich (Germany); Benz, Nikolaus; Doerfler, Michael; Gut, Martin [ZAE Bayern, Solar Thermal and Biomass Dept., Munich (Germany); Kose, Erwin [microtherm Energietecjnik GmbH, Lods, 25 (France)

2000-07-01

We present an approach to find optimal reflector shapes for non-tracking solar collectors under practical constraints. We focus on cylindrical absorbers and reflectors with translational symmetry. Under idealised circumstances, edge ray reflectors are well known to be optimal. However, it is not clear how optimal reflectors should be shaped in order to obtain maximum utilisable energy for given operating temperatures under practical constraints like reflectivity less than unity, real radiation data, size limits, and gaps between the reflector and the absorber. For a prototype collector with a symmetric edge ray reflector and a tubular absorber, we derive from calorimetric measurements under outdoor conditions the optical efficiency as a function of the incidence angle. Using numerical optimisation and raytracing, we compare truncated symmetric edge ray reflectors, truncated asymmetric edge ray reflectors and free forms parametrized by Bezier splines. We find that asymmetric edge ray reflectors are optimal. For reasonable operating conditions, truncated asymmetric edge ray reflectors allow much better land use and easily adapt to a large range of roof tilt angles with marginal changes in collector construction. Except near the equator, they should increase the yearly utilisable energy per absorber tube by several percent as compared to the prototype collector with symmetric reflectors. (Author)

A W-Band Radiometer with the Offset Parabolic Antenna for Radiometric Measurements

Directory of Open Access Journals (Sweden)

Li Wu

2016-01-01

Full Text Available This paper deals with the development of a W-band noise-adding radiometer which combines the millimeter-wave (MMW radiometric measurements with a high-resolution imager. The offset parabolic antenna is presented to achieve an accurate measurement and a high resolution. To reduce the cross-polarization level of the antenna, a multimode feed horn with a multistep structure is proposed to match the focal region fields of the reflector. It has advantages over the corrugated horns in lower mass and easier manufacturing. In addition, due to an unavoidable settling time for the noise-adding radiometer output signal passing through the low-pass filter, a theoretical criterion for the optimum duty cycle determination to reject extraneous contributions from the transient is proposed in this paper. The appropriate duty cycle threshold is 0.33 for the developed W-band radiometer. Also, a geometric correction method is presented to correct the obtained passive image suffering from a distortion for a better image interpretation. Preliminary experimental results are given to illustrate and verify the presented techniques.

Stability analysis of impulsive parabolic complex networks

Energy Technology Data Exchange (ETDEWEB)

Wang Jinliang, E-mail: wangjinliang1984@yahoo.com.cn [Science and Technology on Aircraft Control Laboratory, School of Automation Science and Electrical Engineering, Beihang University, XueYuan Road, No. 37, HaiDian District, Beijing 100191 (China); Wu Huaining [Science and Technology on Aircraft Control Laboratory, School of Automation Science and Electrical Engineering, Beihang University, XueYuan Road, No. 37, HaiDian District, Beijing 100191 (China)

2011-11-15

Highlights: > Two impulsive parabolic complex network models are proposed. > The global exponential stability of impulsive parabolic complex networks are considered. > The robust global exponential stability of impulsive parabolic complex networks are considered. - Abstract: In the present paper, two kinds of impulsive parabolic complex networks (IPCNs) are considered. In the first one, all nodes have the same time-varying delay. In the second one, different nodes have different time-varying delays. Using the Lyapunov functional method combined with the inequality techniques, some global exponential stability criteria are derived for the IPCNs. Furthermore, several robust global exponential stability conditions are proposed to take uncertainties in the parameters of the IPCNs into account. Finally, numerical simulations are presented to illustrate the effectiveness of the results obtained here.

Stability analysis of impulsive parabolic complex networks

International Nuclear Information System (INIS)

Wang Jinliang; Wu Huaining

2011-01-01

Highlights: → Two impulsive parabolic complex network models are proposed. → The global exponential stability of impulsive parabolic complex networks are considered. → The robust global exponential stability of impulsive parabolic complex networks are considered. - Abstract: In the present paper, two kinds of impulsive parabolic complex networks (IPCNs) are considered. In the first one, all nodes have the same time-varying delay. In the second one, different nodes have different time-varying delays. Using the Lyapunov functional method combined with the inequality techniques, some global exponential stability criteria are derived for the IPCNs. Furthermore, several robust global exponential stability conditions are proposed to take uncertainties in the parameters of the IPCNs into account. Finally, numerical simulations are presented to illustrate the effectiveness of the results obtained here.

Solar reflector

Energy Technology Data Exchange (ETDEWEB)

Dvorak, J

1983-01-15

The reflector in the form of part of a cylindrical surface delimited by two envelopes is installed on a platform which can move on an inclined curvilinear path. The angle of inclination of the path depends on the latitude of the locality. The reflected rays are focused on the tubular absorber. One of the axes of the platform is linked to a brake controlled by a sensor for intensity of solar radiation. The sensor is a pipe filled with liquid with high value of the temperature expansion coefficient, for example alcohol. The pipe is insulated from one side and is accessible to the solar rays from the opposite. One end of the pipe is equipped with a bending end or piston. In order to expand the fluid in the sensor, the pipe acts on the brake, and the reflector is installed in a position corresponding to the maximum radiation intensity.

Geological signatures of drillhole radar reflectors in ONKALO

International Nuclear Information System (INIS)

Doese, C.; Gustafsson, J.

2011-12-01

The geological signatures of radar reflectors in ONKALO have been evaluated as a subactivity within the Joint Work Programme 'Rock Suitability Criteria' strategies and methodology' between Svensk Kaernbraenslehantering AB and Posiva Oy. In addition to the geological signature, the usage of geophysical data to predict large fractures was evaluated. Pilot hole radar loggings were carried out using a RAMAC GPR-250 MHz dipole antenna. The radar data were evaluated and reflectors with known position and intersection angle to the pilot hole were correlated with fractures or foliation in the pilot hole and with Tunnel Crosscutting Fractures in the tunnel. This data served as in-data for the evaluation of the geological signatures of radar reflectors. The result of the evaluation is not univocal. Half of the reflectors could be explained by fractures in the pilot hole, but only about 10 % of the reflectors can be explained by Tunnel Crosscutting Fractures. Of these 10 %, 2/3 can also be explained by foliation, leaving only some 3 % of the total reflectors more unambiguously correlated with Tunnel Crosscutting Fractures. The fractures correlated with radar reflectors do not diverge much from other fractures. Fractures having intersection angles of 30 deg- 60 deg are more likely to be detected by radar relative to other. Other properties that seem to be overrepresented in fractures correlated with radar reflectors are quartz and/or graphite content, width ≥0.8 mm and higher alteration (J a ≥3), but the data is not unambiguous. (orig.)

Square Van Atta reflector with conducting mounting flame

DEFF Research Database (Denmark)

Nielsen, Erik Dragø

1970-01-01

A theoretical and numerical analysis of square Van Atta reflectors has been carried out with or without a conducting plate, used for mounting of the antenna elements. The Van Atta reflector investigated has antenna elements which are parallel half-wave dipoles interconnected in pairs by transmiss......A theoretical and numerical analysis of square Van Atta reflectors has been carried out with or without a conducting plate, used for mounting of the antenna elements. The Van Atta reflector investigated has antenna elements which are parallel half-wave dipoles interconnected in pairs...

Ellisoidal reflector for measuring otoacoustic emissions

DEFF Research Database (Denmark)

Epp, Bastian; Heiskanen, Vesa; Pulkki, Ville Topias

2016-01-01

ear canal. This study presents the design and evaluation of a truncated prolate ellipsoidal reflector in combination with a large-diaphragm low-noise microphone to measure OAEs in the open ear canal of human listeners. The reflector was designed to gain information about BM processing at low...

Adaptive Nulling in Hybrid Reflector Antennas

Science.gov (United States)

1992-09-01

correction of reflector distortion and vernier beamsteering, MEEE Trans. Antennas Propagat, 36:1351-1358. 4 Cherrette , A.R., et al (1989) Compensation of...Propagat, 36:1351-1358. 4. Cherrette , A.R., et al (1989) Compensation of reflector antenna surface distortion using an array feed,IEEE Trans. Antennas

Optimization of reflector-boosters for solar flat-collectors

Energy Technology Data Exchange (ETDEWEB)

Profant, M; Weidner, P; Boettcher, A

1979-04-01

To increase the working temperature of solar energy systems two-sided collectors together with appropriate reflectors are used. Here, the efficiency of various reflector shapes was investigated and attempts made to optimize them under several criteria. The results indicate that with cheap and simple to manufacture reflectors good energy gains can be expected.

Precision segmented reflectors for space applications

Science.gov (United States)

Lehman, David H.; Pawlik, Eugene V.; Meinel, Aden B.; Fichter, W. B.

1990-08-01

A project to develop precision segmented reflectors (PSRs) which operate at submillimeter wavelengths is described. The development of a light efficient means for the construction of large-aperture segmented reflecting space-based telescopes is the primary aim of the project. The 20-m Large Deployable Reflector (LDR) telescope is being developed for a survey mission, and it will make use of the reflector panels and materials, structures, and figure control being elaborated for the PSR. The surface accuracy of a 0.9-m PSR panel is shown to be 1.74-micron RMS, the goal of 100-micron RMS positioning accuracy has been achieved for a 4-m erectable structure. A voice-coil actuator for the figure control system architecture demonstrated 1-micron panel control accuracy in a 3-axis evaluation. The PSR technology is demonstrated to be of value for several NASA projects involving optical communications and interferometers as well as missions which make use of large-diameter segmented reflectors.

Design of partially optically stable reflector systems and prisms

Science.gov (United States)

Tsai, Chuang-Yu

2010-09-01

The characteristics and design method of the total optically stable (TOS) reflector systems/prisms were introduced in an early paper (Tsai and Lin in Appl. Opt. 47:4158-4163, 2008), where only two types of TOS reflector system exist, namely preservation or retroreflection. In this paper, we introduce the partially optically stable (POS) reflector system, which is only optically stable about a specific directional vector; nevertheless, the exiting light ray is not restricted to preservation or retroreflection. The proposed paper also presents an analytic method for the design of POS reflector systems comprised of multiple reflectors. Furthermore, it is shown that a POS prism can be obtained by adding two refracting flat boundary surfaces with specific conditions at the entrance and exit positions of the light ray in an optical system with multiple reflectors.

Three-dimensional model of plate geometry and velocity model for Nankai Trough seismogenic zone based on results from structural studies

Science.gov (United States)

Nakanishi, A.; Shimomura, N.; Kodaira, S.; Obana, K.; Takahashi, T.; Yamamoto, Y.; Yamashita, M.; Takahashi, N.; Kaneda, Y.

2012-12-01

In the Nankai Trough subduction seismogenic zone, the Nankai and Tonankai earthquakes had often occurred simultaneously, and caused a great event. In order to reduce a great deal of damage to coastal area from both strong ground motion and tsunami generation, it is necessary to understand rupture synchronization and segmentation of the Nankai megathrust earthquake. For a precise estimate of the rupture zone of the Nankai megathrust event based on the knowledge of realistic earthquake cycle and variation of magnitude, it is important to know the geometry and property of the plate boundary of the subduction seismogenic zone. To improve a physical model of the Nankai Trough seismogenic zone, the large-scale high-resolution wide-angle and reflection (MCS) seismic study, and long-term observation has been conducted since 2008. Marine active source seismic data have been acquired along grid two-dimensional profiles having the total length of ~800km every year. A three-dimensional seismic tomography using active and passive seismic data observed both land and ocean bottom stations have been also performed. From those data, we found that several strong lateral variations of the subducting Philippine Sea plate and overriding plate corresponding to margins of coseismic rupture zone of historical large event occurred along the Nankai Trough. Particularly a possible prominent reflector for the forearc Moho is recently imaged in the offshore side in the Kii channel at the depth of ~18km which is shallower than those of other area along the Nankai Trough. Such a drastic variation of the overriding plate might be related to the existence of the segmentation of the Nankai megathrust earthquake. Based on our results derived from seismic studies, we have tried to make a geometrical model of the Philippine Sea plate and a three-dimensional velocity structure model of the Nankai Trough seismogenic zone. In this presentation, we will summarize major results of out seismic studies, and

Solar parabolic dish technology evaluation report

Science.gov (United States)

Lucas, J. W.

1984-01-01

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

The study of the focal trough in panoramic radiograph

International Nuclear Information System (INIS)

Park, C. S.; Kim, H. P.

1982-01-01

In the study of the focal trough of panoramic radiograph, using the Moritta company Panex EC a series of 48 exposures were taken with the 6-18 brass pins placed in the holes of the plastic model plate, then evaluated by 4 observers. The author analyzed the focal trough defined by the sharpness criteria and calculated the vertical and horizontal magnification range in the corrected focal trough. The results were as follows; 1. Continuous focal trough was not defined in the anterior region using a very high degree of sharpness. 2. As degree of sharpness used in the analysis became less, focal trough was continuous in the anterior and posterior regions, symmetrized bilaterally, and the widths of the focal trough increased more in the posterior region. 3. As sharpness criteria were reduced, the percentage range of image magnification increased in both vertical and horizontal magnification, and especially the percentage range of horizontal magnification was greater than that of vertical magnification.

Design of node record for fast active reflector

International Nuclear Information System (INIS)

Wu Wenqing; Luo Mingcheng; Tang Pengyi; Liu Jiajing; Wang Jian

2014-01-01

Active Reflector is the one of the innovations of Five hundred meter Aperture Spherical Telescope (FAST) whose performance touches on that of the overall telescope. Therefore a real time control system is needed by the Active Reflector System. In this paper, a new record type-node record is designed for EPICS-based active reflector control system of FAST, according to more than 2000 controlled node, which will be convenient for node management of IOC and prove the reusage of IOC codes. The record type is used in design of active reflector control system of FAST Miyun model. (authors)

Reflector Performance Study in Ultra-long Cycle Fast Reactor

International Nuclear Information System (INIS)

Tak, Taewoo; Kong, Chidong; Choe, Jiwon; Lee, Deokjung

2013-01-01

There are reflector assemblies outside the fuel region, surrounding the fuel assemblies and axial reflector is located at the bottom of the core to control the neutron leakage fraction which is an important factor in fast reactor system. HT-9 was used as a reflector material as well as a structure material. In this study, alternative reflector materials were proposed and their reflection performance was tested and studied focused on its physics. ODS-MA957 and SiC were chosen from iron based alloy and ceramic respectively. The two materials were tested and compared with HT-9 in UCFR-1000 as a radial and an axial reflector and it was evaluated from the neutronics point of view with comparing the core life and the coolant void reactivity. The calculation and evaluation were performed by McCARD Monte Carlo code. The reflector materials for UCFR-1000 have been investigated in the aspect of neutronics. The reflection effect shows different performance corresponding to reflector material used. Also, the neutron energy spectrum is affected by changing materials which causes spectrum softening but it is not enough to influence the core life. With more reflector material candidates such as lead-based liquid metal, reflection performance and core parameter study will be investigated for next step

Approaching conversion limit with all-dielectric solar cell reflectors.

Science.gov (United States)

Fu, Sze Ming; Lai, Yi-Chun; Tseng, Chi Wei; Yan, Sheng Lun; Zhong, Yan Kai; Shen, Chang-Hong; Shieh, Jia-Min; Li, Yu-Ren; Cheng, Huang-Chung; Chi, Gou-chung; Yu, Peichen; Lin, Albert

2015-02-09

Metallic back reflectors has been used for thin-film and wafer-based solar cells for very long time. Nonetheless, the metallic mirrors might not be the best choices for photovoltaics. In this work, we show that solar cells with all-dielectric reflectors can surpass the best-configured metal-backed devices. Theoretical and experimental results all show that superior large-angle light scattering capability can be achieved by the diffuse medium reflectors, and the solar cell J-V enhancement is higher for solar cells using all-dielectric reflectors. Specifically, the measured diffused scattering efficiency (D.S.E.) of a diffuse medium reflector is >0.8 for the light trapping spectral range (600nm-1000nm), and the measured reflectance of a diffuse medium can be as high as silver if the geometry of embedded titanium oxide(TiO(2)) nanoparticles is optimized. Moreover, the diffuse medium reflectors have the additional advantage of room-temperature processing, low cost, and very high throughput. We believe that using all-dielectric solar cell reflectors is a way to approach the thermodynamic conversion limit by completely excluding metallic dissipation.

Parabolic features and the erosion rate on Venus

Science.gov (United States)

Strom, Robert G.

1993-01-01

The impact cratering record on Venus consists of 919 craters covering 98 percent of the surface. These craters are remarkably well preserved, and most show pristine structures including fresh ejecta blankets. Only 35 craters (3.8 percent) have had their ejecta blankets embayed by lava and most of these occur in the Atla-Beta Regio region; an area thought to be recently active. parabolic features are associated with 66 of the 919 craters. These craters range in size from 6 to 105 km diameter. The parabolic features are thought to be the result of the deposition of fine-grained ejecta by winds in the dense venusian atmosphere. The deposits cover about 9 percent of the surface and none appear to be embayed by younger volcanic materials. However, there appears to be a paucity of these deposits in the Atla-Beta Regio region, and this may be due to the more recent volcanism in this area of Venus. Since parabolic features are probably fine-grain, wind-deposited ejecta, then all impact craters on Venus probably had these deposits at some time in the past. The older deposits have probably been either eroded or buried by eolian processes. Therefore, the present population of these features is probably associated with the most recent impact craters on the planet. Furthermore, the size/frequency distribution of craters with parabolic features is virtually identical to that of the total crater population. This suggests that there has been little loss of small parabolic features compared to large ones, otherwise there should be a significant and systematic paucity of craters with parabolic features with decreasing size compared to the total crater population. Whatever is erasing the parabolic features apparently does so uniformly regardless of the areal extent of the deposit. The lifetime of parabolic features and the eolian erosion rate on Venus can be estimated from the average age of the surface and the present population of parabolic features.

Efficient Wave Energy Amplification with Wave Reflectors

DEFF Research Database (Denmark)

Kramer, Morten Mejlhede; Frigaard, Peter Bak

2002-01-01

Wave Energy Converters (WEC's) extract wave energy from a limited area, often a single point or line even though the wave energy is generally spread out along the wave crest. By the use of wave reflectors (reflecting walls) the wave energy is effectively focused and increased to approximately 130......-140%. In the paper a procedure for calculating the efficiency and optimizing the geometry of wave reflectors are described, this by use of a 3D boundary element method. The calculations are verified by laboratory experiments and a very good agreement is found. The paper gives estimates of possible power benifit...... for different geometries of the wave reflectors and optimal geometrical design parameters are specified. On this basis inventors of WEC's can evaluate whether a specific WEC possible could benefit from wave reflectors....

International Workshop on Elliptic and Parabolic Equations

CERN Document Server

Schrohe, Elmar; Seiler, Jörg; Walker, Christoph

2015-01-01

This volume covers the latest research on elliptic and parabolic equations and originates from the international Workshop on Elliptic and Parabolic Equations, held September 10-12, 2013 at the Leibniz Universität Hannover. It represents a collection of refereed research papers and survey articles written by eminent scientist on advances in different fields of elliptic and parabolic partial differential equations, including singular Riemannian manifolds, spectral analysis on manifolds, nonlinear dispersive equations, Brownian motion and kernel estimates, Euler equations, porous medium type equations, pseudodifferential calculus, free boundary problems, and bifurcation analysis.

Effect of graphite reflector on activation of fusion breeding blanket

International Nuclear Information System (INIS)

Lee, Cheol Woo; Lee, Young-Ouk; Lee, Dong Won; Cho, Seungyon; Ahn, Mu-Young

2016-01-01

Highlights: • The graphite reflector concept has been applied in the design of the Korea HCCR TBM for ITER and this concept is also a candidate design option for Korea Demo. • In the graphite reflector, C-14, B-11 and Be-10 are produced after an irradiation. Impurities in both case of beryllium and graphite is dominant in the shutdown dose after an irradiation. • Based on the evaluation, the graphite reflector is a good alternative of the beryllium multiplier in the view of induced activity and shutdown dose. But C-14 produced in the graphite reflector should be considered carefully in the view of radwaste management. - Abstract: Korea has proposed a Helium-Cooled Ceramic Reflector (HCCR) breeding blanket concept relevant to fusion power plants. Here, graphite is used as a reflector material by reducing the amount of beryllium multiplier. In this paper, activity analysis was performed and the effect of graphite reflector in the view of activation was compared to the beryllium multiplier. As a result, it is expected that using the graphite reflector instead of the beryllium multiplier decreases total activity very effectively. But the graphite reflector produces C-14 about 17.2 times than the beryllium multiplier. Therefore, C-14 produced in the graphite reflector is expected as a significant nuclide in the view of radwaste management.

A comparison of prototype compound parabolic collector-reactors (CPC) on the road to SOLARDETOX technology.

Science.gov (United States)

Funken, K H; Sattler, C; Milow, B; De Oliveira, L; Blanco, J; Fernández, P; Malato, S; Brunott, M; Dischinge, N; Tratzky, S; Musci, M; de Oliveira, J C

2001-01-01

Solar photocatalytic detoxification of non-biodegradable chlorinated hydrocarbon solvents (NBCS) is carried out in different concentrating and non concentrating devices using TiO2 as a photocatalyst fixed on the inner surface of the reaction tubes or as a slurry catalyst which has to be removed from the treated water. The reaction is most effective using 200 mg/l of TiO2 as a slurry in a non concentrating CPC reactor. The concentrating parabolic trough reactor has a poor activity because of its minor irradiated reactor surface. Catalyst coated glass tubes are less efficient then the used slurry catalyst. Their advantage is that no catalyst has not to be removed from the treated water and there is no loss of activity during treatment. Yet their physical stability is not sufficient to be competitive to the slurry catalyst. Nevertheless the degradation results are very promising and will possibly lead to commercial applications of this technology.

Optimal design of orientation of PV/T collector with reflectors

International Nuclear Information System (INIS)

Kostic, Lj.T.; Pavlovic, T.M.; Pavlovic, Z.T.

2010-01-01

Hybrid conversion of solar radiation implies simultaneous solar radiation conversion into thermal and electrical energy in the PV/Thermal collector. In order to get more thermal and electrical energy, flat solar radiation reflectors have been mounted on PV/T collector. To obtain higher solar radiation intensity on PV/T collector, position of reflectors has been changed and optimal position of reflectors has been determined by both experimental measurements and numerical calculation so as to obtain maximal concentration of solar radiation intensity. The calculated values have been found to be in good agreement with the measured ones, both yielding the optimal position of the flat reflector to be the lowest (5 o ) in December and the highest (38 o ) in June. In this paper, the thermal and electrical efficiency of PV/T collector without reflectors and with reflectors in optimal position have been calculated. Using these results, the total efficiency and energy-saving efficiency of PV/T collector have been determined. Energy-saving efficiency for PV/T collector without reflectors is 60.1%, which is above the conventional solar thermal collector, whereas the energy-saving efficiency for PV/T collector with reflectors in optimal position is 46.7%, which is almost equal to the values for conventional solar thermal collector. Though the energy-saving efficiency of PV/T collector decreases slightly with the solar radiation intensity concentration factor, i.e. the thermal and electrical efficiency of PV/T collector with reflectors are lower than those of PV/T collector without reflectors, the total thermal and electrical energy generated by PV/T collector with reflectors in optimal position are significantly higher than total thermal and electrical energy generated by PV/T collector without reflectors.

Nonimaging reflectors as functionals of the desired irradiance

International Nuclear Information System (INIS)

Winston, R.; Ries, H.

1993-01-01

For many tasks in illumination and collection the acceptance angle is required to vary along the reflector. If the acceptance angle function is known, then the reflector profile can be calculated as a functional of it. The total flux seen by an observer from a source of uniform brightness (radiance) is proportional to the sum of the view factor of the source and its reflection. This allows one to calculate the acceptance angle function necessary to produce a certain flux distribution and thereby construct the reflector profile. The authors demonstrate the method for several examples, including finite size sources with reflectors directly joining the source

Manufacturing parabolic mirrors

CERN Multimedia

CERN PhotoLab

1975-01-01

The photo shows the construction of a vertical centrifuge mounted on an air cushion, with a precision of 1/10000 during rotation, used for the manufacture of very high=precision parabolic mirrors. (See Annual Report 1974.)

The sedimentation rates in the Okinawa Trough during the Late Quaternary

Institute of Scientific and Technical Information of China (English)

无

2005-01-01

On the basis of accelerator mass spectrometer radiocarbon (AMS 14C) dating, sedimentation rates of 11 cores collected from the northern to southern Okinawa Trough are discussed. The sedimentation rates in the Okinawa Trough roughly range from 11 to 39 cm/ka, and the average is 23.0 cm/ka. China's continental matter is the main sediment source of the middle Okinawa Trough and has important contribution to the northern and southern Okinawa Trough. The sedimentation rates during the marine oxygen isotope (MIS)2 are uniformly higher than those during MIS 1 in the northern and middle Okinawa Trough while they are on the contrary in the southern Okinawa Trough. Sedimentation rates in the Okinawa Trough can be one of the proxies of sediment source and an indicator of cooling events.

Linear magnetic anomalies and tectonic development of the middle Okinawa Trough

Institute of Scientific and Technical Information of China (English)

无

2001-01-01

-By analyzing the magnetic anomalies, the linear magnetic anomalies in the middle Okinawa Trough are identified. It means that the crust along the spreading axis is broken, and new oceanic crust is formed. Geophysical data have revealed that a model of three extensive episodes occurs in the Okinawa Trough, which can be named as "doming episode" from the Middle to Late Miocene (Phase I), the episode from the Pliocence to Early Pleistocene (Phase Ⅱ ), and the recent "spreading episode" (Phase Ⅲ ). The magnetic anomalies in the middle Okinawa Trough are very similar to those found in the middle Red Sea, indicating that the Okinawa Trough is developing towards the "Red Sea stage". Similar to the Red Sea, there are a "main trough" and a "axial trough" in the Okinawa Trough.

Aeolian sand transport over complex intertidal bar-trough beach topography

Science.gov (United States)

Anthony, Edward J.; Ruz, Marie-Hélène; Vanhée, Stéphane

2009-04-01

Aeolian sand transport on macrotidal beaches with complex intertidal bar-trough topography (ridge-and-runnel beaches) was assessed from experiments in northern France that involved measurements of wind speed, saltation, surface moisture contents, and rates of sand trapping across surveyed portions of the upper beach profile. Beaches exhibiting intertidal bars and troughs are much more complex, topographically, than simple reflective or dissipative beaches. Furthermore, the intertidal bar-trough morphology commonly exhibits strong cross-shore variations in the moisture contents of the beach surface and in patterns of bedform development. The results of four 30-minute experiments, conducted along topographically surveyed portions of the upper beach-dune toe profile, show that troughs act as extremely efficient sand interceptors, because of their permanently saturated state, which also inhibits sand mobilisation. Troughs, thus, limit or segment the dry fetch during conditions of intermittent saltation. Flow lines, inferred from the wind profiles, suggest that complex interactions at the boundary layer are generated by the bar-trough topography. Troughs systematically appear to be characterised by air expansion, while bar faces generate ramp wind acceleration for onshore winds, and sometimes immediate downwind deceleration for offshore winds. These effects may also contribute to cross-shore variations in the rates of sand trapping. Finally, a simple conceptual model of effective fetch development, integrating the effects of the spring-neap tidal range and of gross bar-trough morphological variability over time, is proposed for bar-trough beaches. The model highlights the key theme of fetch segmentation induced by cross-shore differentiation in the moisture contents of the beach surface hinged on the complex topography of multiple bars and troughs.

Solving Variable Coefficient Fourth-Order Parabolic Equation by ...

African Journals Online (AJOL)

Solving Variable Coefficient Fourth-Order Parabolic Equation by Modified initial guess Variational ... variable coefficient fourth order parabolic partial differential equations. The new method shows rapid convergence to the exact solution.

Quasi-optical millimeter wave rotating TE62 mode generator

International Nuclear Information System (INIS)

Li Shaopu; Zhang Conghui; Wang Zhong; Guo Feng; Chen Hongbin; Hu Linlin; Pan Wenwu

2011-01-01

The design,measurement technique and experimental results of rotating TE 6 2 mode generator are presented. The source includes millimeter wave optical system and open coaxial wave guide system. The millimeter wave optical system consists of pyramid antenna, hyperbolical reflector, parabolic reflector and quasi parabolic reflector. The open coaxial wave guide system contains open coaxial wave guide cavity, cylinder wave guide and output antenna. It is tested by network analyser and millimeter wave near field pattern auto-test system, and the purity of rotating TE 6 2 mode at 96.4 GHz is about 97%. (authors)

Acoustic levitation with self-adaptive flexible reflectors.

Science.gov (United States)

Hong, Z Y; Xie, W J; Wei, B

2011-07-01

Two kinds of flexible reflectors are proposed and examined in this paper to improve the stability of single-axis acoustic levitator, especially in the case of levitating high-density and high-temperature samples. One kind is those with a deformable reflecting surface, and the other kind is those with an elastic support, both of which are self-adaptive to the change of acoustic radiation pressure. High-density materials such as iridium (density 22.6 gcm(-3)) are stably levitated at room temperature with a soft reflector made of colloid as well as a rigid reflector supported by a spring. In addition, the containerless melting and solidification of binary In-Bi eutectic alloy (melting point 345.8 K) and ternary Ag-Cu-Ge eutectic alloy (melting point 812 K) are successfully achieved by applying the elastically supported reflector with the assistance of a laser beam.

Wideband QAMC reflector's antenna for low profile applications

Science.gov (United States)

Grelier, M.; Jousset, M.; Mallégol, S.; Lepage, A. C.; Begaud, X.; LeMener, J. M.

2011-06-01

A wideband reflector's antenna based on quasi-artificial magnetic conductor is proposed. To validate the design, an Archimedean spiral has been backed to this new reflector. In comparison to classical solution using absorbent material, the prototype presents a very low thickness of λ/15 at the lowest operating frequency and an improved gain over a 2.4:1 bandwidth. The whole methodology to design this reflector can be applied to other wideband antennas.

Surface Optimization Techniques for Deployable Reflectors, Phase II

Data.gov (United States)

National Aeronautics and Space Administration — Under this and several other programs, CTD has developed TEMBOREG deployable solid-surface reflectors (TEMBOREG Reflectors) to provide future NASA and Air Force...

Principles of solar engineering

CERN Document Server

Goswami, D Yogi

2015-01-01

Introduction to Solar Energy ConversionGlobal Energy Needs and ResourcesSolar EnergyEnergy StorageEconomics of Solar SystemsSummary of RE ResourcesForecast of Future Energy MixReferencesFundamentals of Solar RadiationThe Physics of the Sun and Its Energy TransportThermal Radiation FundamentalsSun-Earth Geometric RelationshipSolar RadiationEstimation of Terrestrial Solar RadiationModels Based on Long-Term Measured Horizontal Solar RadiationMeasurement of Solar RadiationSolar Radiation Mapping Using Satellite DataReferencesSuggested ReadingsSolar Thermal CollectorsRadiative Properties and Characteristics of MaterialsFlat-Plate CollectorsTubular Solar Energy CollectorsExperimental Testing of CollectorsConcentrating Solar CollectorsParabolic Trough ConcentratorCompound-Curvature Solar ConcentratorsCentral Receiver CollectorFresnel Reflectors and LensesSolar Concentrator SummaryReferencesSuggested ReadingThermal Energy Storage and TransportThermal Energy StorageTypes of TESDesign of Storage SystemEnergy Transport ...

Advanced reflector materials for solar concentrators

Science.gov (United States)

Jorgensen, Gary; Williams, Tom; Wendelin, Tim

1994-10-01

This paper describes the research and development at the US National Renewable Energy Laboratory (NREL) in advanced reflector materials for solar concentrators. NREL's research thrust is to develop solar reflector materials that maintain high specular reflectance for extended lifetimes under outdoor service conditions and whose cost is significantly lower than existing products. Much of this work has been in collaboration with private-sector companies that have extensive expertise in vacuum-coating and polymer-film technologies. Significant progress and other promising developments will be discussed. These are expected to lead to additional improvements needed to commercialize solar thermal concentration systems and make them economically attractive to the solar manufacturing industry. To explicitly demonstrate the optical durability of candidate reflector materials in real-world service conditions, a network of instrumented outdoor exposure sites has been activated.

Vancomycin AUC/MIC and Corresponding Troughs in a Pediatric Population.

Science.gov (United States)

Kishk, Omayma A; Lardieri, Allison B; Heil, Emily L; Morgan, Jill A

2017-01-01

Adult guidelines suggest an area under the curve/minimum inhibitory concentration (AUC/MIC) > 400 corresponds to a vancomycin trough serum concentration of 15 to 20 mg/L for methicillin-resistant Staphylococcus aureus infections, but obtaining these troughs in children are difficult. The primary objective of this study was to assess the likelihood that 15 mg/kg of vancomycin every 6 hours in a child achieves an AUC/MIC > 400. This retrospective chart review included pediatric patients >2 months to AUCs were calculated four times using three pharmacokinetic methods. A total of 36 patients with 99 vancomycin trough serum concentrations were assessed. Baseline characteristics were similar between groups. For troughs in group 1 (n = 55), the probability of achieving an AUC/MIC > 400 ranged from 16.4% to 90.9% with a median trough concentration of 11.4 mg/L, while in group 2 (n = 44) the probability of achieving AUC/MIC > 400 ranged from 15.9% to 54.5% with mean trough concentration of 9.2 mg/L. The AUC/MICs were not similar between the different pharmacokinetic methods used; however, a trapezoidal equation (Method A) yielded the highest correlation coefficient (r 2 = 0.59). When dosing every 6 hours, an AUC/MIC of 400 correlated to a trough serum concentration of 11 mg/L. The probability of achieving an AUC/MIC > 400 using only a trough serum concentration and an MIC with patients receiving 15 mg/kg every 6 hours is variable based on the method used to calculate the AUC. An AUC/MIC of 400 in children correlated to a trough concentration of 11 mg/L using a trapezoidal Method to calculate AUC.

Reconfigurable antenna using plasma reflector

Science.gov (United States)

Jusoh, Mohd Taufik; Ahmad, Khairol Amali; Din, Muhammad Faiz Md; Hashim, Fakroul Ridzuan

2018-02-01

This paper presents the feasibility study and design of plasma implementation in industrial, scientific and medical (ISM) communication band. A reflector antenna with rounded shaped is proposed to collimate beam in particular direction radiated by a quarter wave antenna operating at 2.4GHz. The simulations result has shown that by using plasma as the reflector elements, the gain, directivity and radiation patterns are identical with metal elements with only small different in the broadside direction. The versatility of the antenna is achievable by introducing electrical reconfigurable option to change the beam pattern.

Performance of a PV module augmented by a plane reflector

Energy Technology Data Exchange (ETDEWEB)

Ahmad, G. E; Hussein, H. M. S; Mohamad, M. A [Dokki, Giza (Egypt)

2000-07-01

This paper presents a comparative experimental study on the performance of a PV module augmented by a south facing titled plane reflector and another identical one without reflector. The tilt angles of the two PV modules and reflector overhang are selected to be according to a previous theoretical study by the authors. The reflector tilt angle has been changed once a month so that the reflected beams from the plane reflector cover the total surface area of the PV module all days of every month during the high solar radiation period (i.e. three hours before and after solar noon). The study has been carried out on the two PV modules for a complete year under the actual atmospheric conditions of Cairo, Egypt. The measuring system used in the study comprises a data acquisition system, a computer, an electronic load and weather station. The experimental results indicate that the plane reflector enhances the yearly output energy of the PV module y about 22%. [Spanish] Este articulo presenta un estudio comparativo experimental sobre el rendimiento de un modulo de PV aumentado por un reflector plano inclinado mirando hacia el sur y otro identico sin reflector. Los angulos de inclinacion de los dos modulos y el reflector sobresaliente se seleccionan para que esten de acuerdo con un estudio teorico previo hecho por los autores. El angulo de inclinacion del reflector se cambio una vez al mes de manera que los rayos reflejados por el reflector plano cubrieran el area total de la superficie del modulo de PV todos los dias de cada mes durante el periodo de radiacion alto (o sea tres horas antes y despues del medio dia solar). El estudio ha sido llevado a cabo en dos modulos de PV durante un ano completo bajo condiciones atmosfericas reales de El Cairo, Egipto. El sistema de medicion usado en el estudio comprende un sistema de adquisicion de datos, una computadora, una memoria electronica y una estacion climatologica. Los resultados experimentales indican que el reflector plano

The F-region trough: seasonal morphology and relation to interplanetary magnetic field

Directory of Open Access Journals (Sweden)

M. Voiculescu

2006-03-01

Full Text Available We present here the results of a statistical study of the ionospheric trough observed in 2003 by means of satellite tomography. We focus on the seasonal morphology of the trough occurrence and investigate the trough latitude, width and the horizontal gradients at the edges, at different magnetic local times, as well as their relations to geomagnetic activity and the interplanetary magnetic field. A seasonal effect is noticed in the diurnal variation of the trough latitude, indicating that summer clearly differs from the other seasons. In winter the troughs seem to follow the solar terminator. The width of the trough has a diurnal variation and it depends on the season, as well. The broadest troughs are observed in winter and the narrowest ones in summer. A discontinuity in the diurnal variation of the trough latitude is observed before noon. It is suggested that this is an indication of a difference between the generation mechanisms of morningside and eveningside troughs. The density gradients at the edges have a complex dependence on the latitude of the trough and on geomagnetic activity. The photoionization and the auroral precipitation are competing in the formation of the trough walls at different magnetic local times. An important finding is that the interplanetary magnetic field plays a role in the occurrence of the trough at different levels of geomagnetic activity. This is probably associated with the topology of the polar cap convection pattern, which depends on the directions of the IMF components By and Bz.

The F-region trough: seasonal morphology and relation to interplanetary magnetic field

Directory of Open Access Journals (Sweden)

M. Voiculescu

2006-03-01

Full Text Available We present here the results of a statistical study of the ionospheric trough observed in 2003 by means of satellite tomography. We focus on the seasonal morphology of the trough occurrence and investigate the trough latitude, width and the horizontal gradients at the edges, at different magnetic local times, as well as their relations to geomagnetic activity and the interplanetary magnetic field. A seasonal effect is noticed in the diurnal variation of the trough latitude, indicating that summer clearly differs from the other seasons. In winter the troughs seem to follow the solar terminator. The width of the trough has a diurnal variation and it depends on the season, as well. The broadest troughs are observed in winter and the narrowest ones in summer. A discontinuity in the diurnal variation of the trough latitude is observed before noon. It is suggested that this is an indication of a difference between the generation mechanisms of morningside and eveningside troughs. The density gradients at the edges have a complex dependence on the latitude of the trough and on geomagnetic activity. The photoionization and the auroral precipitation are competing in the formation of the trough walls at different magnetic local times. An important finding is that the interplanetary magnetic field plays a role in the occurrence of the trough at different levels of geomagnetic activity. This is probably associated with the topology of the polar cap convection pattern, which depends on the directions of the IMF components B_y and B_z.

APPLICATION OF QUATERNIONS FOR REFLECTOR PARAMETER

Directory of Open Access Journals (Sweden)

I. A. Konyakhin

2016-09-01

Full Text Available Subject of Research. The paper deals with application of quaternions for optimization of reflector parameters at autocollimation measurements in comparison with a matrix method. Computer-based results on the quaternionic models are presented that have given the possibility to determine conditions of measurement error reduction in view of apriori information on the rotation axis position. The practical synthesis technique for tetrahedron reflector parameters using found ratios is considered. Method. Originally, received conditions for reduction of autocollimation system measurement error are determined with the use of a matrix method for definition of an angular object position as a set of three equivalent consecutive turns about coordinate axes. At realization of these conditions the numerous recalculation of orientation parameters between various systems of coordinates is necessary that increases complexity and reduces resulting accuracy of autocollimation system at practical measurements. The method of quaternions gives the possibility to analyze the change of an absolute angular position in space, thus, there are conditions of accuracy increase regardless of the used systems of coordinates. Main Results. Researches on the mathematical model have shown, that the orthogonal arrangement of two basic constant directions for autocollimator tetrahedron reflector is optimal with respect to criterion of measurement error reduction at bisection arrangement of actual turn axis against them. Practical Relevance. On the basis of the found ratios between tetrahedron reflector angles and angles of its initial orientation parameters we have developed a practical method of reflector synthesis for autocollimation measurements in case of apriori information on an actual turn axis at monitoring measurements of the shaft or pipelines deformations.

49 CFR 393.26 - Requirements for reflectors.

Science.gov (United States)

2010-10-01

... case of motor vehicles so constructed that requirement for a 381 mm (15-inch) minimum height above the... used in lieu of reflex reflectors if the material as used on the vehicle, meets the performance... motor vehicle. (3) Such surfaces shall be at least 3 inches from any required lamp or reflector unless...

White LED motorcycle headlamp design

Science.gov (United States)

Sun, Wen-Shing

2015-09-01

The motorcycle headlamp is composed of a white LED module, an elliptical reflector, a parabolic reflector and a toric lens. We use non-sequential ray to improve the optical efficiency of the compound reflectors. Using the toric lens can meet ECE_113 regulation and obtain a good uniformity.

System concept for a moderate cost Large Deployable Reflector (LDR)

Science.gov (United States)

Swanson, P. N.; Breckinridge, J. B.; Diner, A.; Freeland, R. E.; Irace, W. R.; Mcelroy, P. M.; Meinel, A. B.; Tolivar, A. F.

1986-01-01

A study was carried out at JPL during the first quarter of 1985 to develop a system concept for NASA's LDR. Major features of the concept are a four-mirror, two-stage optical system; a lightweight structural composite segmented primary reflector; and a deployable truss backup structure with integral thermal shield. The two-stage optics uses active figure control at the quaternary reflector located at the primary reflector exit pupil, allowing the large primary to be passive. The lightweight composite reflector panels limit the short-wavelength operation to approximately 30 microns but reduce the total primary reflector weight by a factor of 3 to 4 over competing technologies. On-orbit thermal analysis indicates a primary reflector equilibrium temperature of less than 200 K with a maximum gradient of about 5 C across the 20-m aperture. Weight and volume estimates are consistent with a single Shuttle launch, and are based on Space Station assembly and checkout.

Optimization of MNSR upper reflector material and dimensions

International Nuclear Information System (INIS)

Albarhoum, M.

2007-04-01

Calculations for the optimization of the material and dimensions of the Syrian MNSR was performed. Calculations showed that the considerably important reflectors in this case are Beryllium, Heavy water and Graphite. Dimensions of the reflector cannot any way exceed the Shim Tray dimensions. Two different ways of filling the Shim Tray with the reflector material were established: 1- the radial filling mode, and 2- the axial mode. Both modes can be performed using single sectors or cumulative ones. The axial mode proved to be better than the radial one. The axial cumulative mode proved to be more efficient than the single axial one. The axial cumulative mode was studied from two points of view; the neutronic and the economic ones. From the neutronic point of view the beryllium proved to be the best reflector, and the best dimensions were found to coincide with a thickness equal to 0.11235 cm with the bottom end being 0.4494 cm distant from the bottom of the Shim Tray. From the economic point of view it was found that the cost of the reactivity unit is the smallest when the Graphite is used. Results of this study can be applied directly to the Syrian MNSR since fabrication of any plastic containment for the reflector can easily be achieved. This is because the reactivity worth resulting from mass unit of the reflector varies depending on its position positions in the Shim Tray.(author)

Acoustically damped metal oil trough for internal combustion engines. Schallgedaempfte Blech-Oelwanne fuer Brennkraftmaschinen

Energy Technology Data Exchange (ETDEWEB)

Kubis, H.

1991-03-28

The invention refers to an acoustically damped oil trough. As there are strict requirements for reducing the noise emission from internal combustion engines, according to the invention it is proposed that the oil trough should be surrounded by an outer trough, where the outer trough is made of plastic or sheet steel in one or more layers. To avoid noise bridges, the oil trough and outer trough are separated by elastomer elements. The outer trough achieves a reasonably priced increase in sound insulation. It is also possible to backfit an outer trough on engines.

Deployable reflector configurations

Science.gov (United States)

Meinel, A. B.; Meinel, M. P.; Woolf, N. J.

Both the theoretical reasons for considering a non-circular format for the Large Deployable Reflector, and a potentially realizable concept for such a device, are discussed. The optimum systems for diffraction limited telescopes with incoherent detection have either a single filled aperture, or two such apertures as an interferometer to synthesize a larger aperture. For a single aperture of limited area, a reflector in the form of a slot can be used to give increased angular resolution. It is shown how a 20 x 8 meter telescope can be configured to fit the Space Shuttle bay, and deployed with relatively simple operations. The relationship between the sunshield design and the inclination of the orbit is discussed. The possible use of the LDR as a basic module to permit the construction of supergiant space telescopes and interferometers both for IR/submm studies and for the entire ultraviolet through mm wave spectral region is discussed.

Partial differential equations of parabolic type

CERN Document Server

Friedman, Avner

2008-01-01

This accessible and self-contained treatment provides even readers previously unacquainted with parabolic and elliptic equations with sufficient background to understand research literature. Author Avner Friedman - Director of the Mathematical Biosciences Institute at The Ohio State University - offers a systematic and thorough approach that begins with the main facts of the general theory of second order linear parabolic equations. Subsequent chapters explore asymptotic behavior of solutions, semi-linear equations and free boundary problems, and the extension of results concerning fundamenta

Laser reflector with an interference coating

International Nuclear Information System (INIS)

Vol'pyan, O D; Semenov, A A; Yakovlev, P P

1998-01-01

An analysis was made of the reflectivity of interference coatings intended for the use in optical pumping of solid-state lasers. Ruby and Nd 3+ :YAG lasers were used as models in comparative pumping efficiency measurements, carried out employing reflectors with interference and silver coatings. Estimates of the service life of reflectors with interference coatings were obtained. The power of a thermo-optical lens was reduced by the use of such coatings in cw lasers. (laser system components)

Disordered animal multilayer reflectors and the localization of light

Science.gov (United States)

Jordan, T. M.; Partridge, J. C.; Roberts, N. W.

2014-01-01

Multilayer optical reflectors constructed from ‘stacks’ of alternating layers of high and low refractive index dielectric materials are present in many animals. For example, stacks of guanine crystals with cytoplasm gaps occur within the skin and scales of fish, and stacks of protein platelets with cytoplasm gaps occur within the iridophores of cephalopods. Common to all these animal multilayer reflectors are different degrees of random variation in the thicknesses of the individual layers in the stack, ranging from highly periodic structures to strongly disordered systems. However, previous discussions of the optical effects of such thickness disorder have been made without quantitative reference to the propagation of light within the reflector. Here, we demonstrate that Anderson localization provides a general theoretical framework to explain the common coherent interference and optical properties of these biological reflectors. Firstly, we illustrate how the localization length enables the spectral properties of the reflections from more weakly disordered ‘coloured’ and more strongly disordered ‘silvery’ reflectors to be explained by the same physical process. Secondly, we show how the polarization properties of reflection can be controlled within guanine–cytoplasm reflectors, with an interplay of birefringence and thickness disorder explaining the origin of broadband polarization-insensitive reflectivity. PMID:25339688

Phase II Final Report

Energy Technology Data Exchange (ETDEWEB)

Schuknecht, Nate [Project Manager; White, David [Principle Investigator; Hoste, Graeme [Research Engineer

2014-09-11

The SkyTrough DSP will advance the state-of-the-art in parabolic troughs for utility applications, with a larger aperture, higher operating temperature, and lower cost. The goal of this project was to develop a parabolic trough collector that enables solar electricity generation in the 2020 marketplace for a 216MWe nameplate baseload power plant. This plant requires an LCOE of 9¢/kWhe, given a capacity factor of 75%, a fossil fuel limit of 15%, a fossil fuel cost of $6.75/MMBtu, $25.00/kWht thermal storage cost, and a domestic installation corresponding to Daggett, CA. The result of our optimization was a trough design of larger aperture and operating temperature than has been fielded in large, utility scale parabolic trough applications: 7.6m width x 150m SCA length (1,118m2 aperture), with four 90mm diameter × 4.7m receivers per mirror module and an operating temperature of 500°C. The results from physical modeling in the System Advisory Model indicate that, for a capacity factor of 75%: The LCOE will be 8.87¢/kWhe. SkyFuel examined the design of almost every parabolic trough component from a perspective of load and performance at aperture areas from 500 to 2,900m2. Aperture-dependent design was combined with fixed quotations for similar parts from the commercialized SkyTrough product, and established an installed cost of $130/m2 in 2020. This project was conducted in two phases. Phase I was a preliminary design, culminating in an optimum trough size and further improvement of an advanced polymeric reflective material. This phase was completed in October of 2011. Phase II has been the detailed engineering design and component testing, which culminated in the fabrication and testing of a single mirror module. Phase II is complete, and this document presents a summary of the comprehensive work.

Mixed hyperbolic-second-order-parabolic formulations of general relativity

International Nuclear Information System (INIS)

Paschalidis, Vasileios

2008-01-01

Two new formulations of general relativity are introduced. The first one is a parabolization of the Arnowitt-Deser-Misner formulation and is derived by the addition of combinations of the constraints and their derivatives to the right-hand side of the Arnowitt-Deser-Misner evolution equations. The desirable property of this modification is that it turns the surface of constraints into a local attractor because the constraint propagation equations become second-order parabolic independently of the gauge conditions employed. This system may be classified as mixed hyperbolic--second-order parabolic. The second formulation is a parabolization of the Kidder-Scheel-Teukolsky formulation and is a manifestly mixed strongly hyperbolic--second-order-parabolic set of equations, bearing thus resemblance to the compressible Navier-Stokes equations. As a first test, a stability analysis of flat space is carried out and it is shown that the first modification exponentially damps and smoothes all constraint-violating modes. These systems provide a new basis for constructing schemes for long-term and stable numerical integration of the Einstein field equations.

Localization of the pumping reflector for a Nd:YAG laser

Energy Technology Data Exchange (ETDEWEB)

Kim, Kwang Suk; Kim, Chul Joong [Korea Atomic Energy Research Institute, Taejon (Korea, Republic of)

1994-12-01

For the first year plan of this program, the pumping reflectors, which are gold plated reflectors and ceramic diffuse reflectors, of the Nd:YAG laser have been localized. The laser output performances with these reflectors have been investigated. Developed reflectors can be applied successfully to our commercialized Nd:YAG laser which was worked in previous project. We designed the optical pumping system with GaAlAs diode laser bar to improve the pumping efficiency. Moreover, we investigated a simple pumping technique without changing the fleshlamp, which makes the Nd:YAG laser operate in a cw, a pulsed, and a mixed of the two mode. We expert many new applications of this diversification of output pulse shapes in industry and in medicine. 38 figs, 9 tabs, 18 refs. (Author).

Full reflector thickness and isolation thickness on neutron transport

International Nuclear Information System (INIS)

Sakai, Tomohiro; Naito, Yoshitaka; Komuro, Yuichi.

1988-08-01

A method to determine ''full reflector thickness'' and ''isolation thickness'', which is utilized for criticality safety evaluation on nuclear fuel facilities, was proposed in this paper. Firstly, a calculation was tryed to obtain the two kinds of thicknesses from the result of criticality calculations for a specific case. Then, two simple equations which calculates the two kinds of thicknesses were made from the relation between reflector (or isolator) thickness and k eff , and one-group diffusion theory. Finally, we proposed a new method to determine the thicknesses. From the method we proposed, ''full reflector thickness'' and ''isolation thickness'' can be obtain using the equations and migration length of the reflector (or isolator) and infinite and effective multiplication factor of the fuel. (author)

Ray Tracing modelling of reflector for vertical bifacial panel

DEFF Research Database (Denmark)

Jakobsen, Michael Linde; Thorsteinsson, Sune; Poulsen, Peter Behrensdorff

2016-01-01

Bifacial solar panels have recently become a new attractive building block for PV systems. In this work we propose a reflector system for a vertical bifacial panel, and use ray tracing modelling to model the performance. Particularly, we investigate the impact of the reflector volume being filled...... with a refractive medium, and shows the refractive medium improves the reflector performance since it directs almost all the light incident on the incoming plane into the PV panel....

Simulation study of resonant reflector for S-band BWO

International Nuclear Information System (INIS)

Choyal, Y; Parmar, Nidhi; Saini, Ajay Kumar; Chhotray, S K; Bhat, K S; Kumar, Lalit

2012-01-01

This paper presents the result of simulation studies of resonant reflector used for reflection of backward wave in relativistic BWO. The resonant reflector is modelled and analyzed by CST MWS for TM 01 . A TM 01 mode is fed at the output end of the BWO and signal is observed at the cathode end. Results show that 90 percent of the backward TM 01 wave is get reflected back by the locked TM 02 mode in the resonant reflector.

Bandwidth Study of the Microwave Reflectors with Rectangular Corrugations

Science.gov (United States)

Zhang, Liang; He, Wenlong; Donaldson, Craig R.; Cross, Adrian W.

2016-09-01

The mode-selective microwave reflector with periodic rectangular corrugations in the inner surface of a circular metallic waveguide is studied in this paper. The relations between the bandwidth and reflection coefficient for different numbers of corrugation sections were studied through a global optimization method. Two types of reflectors were investigated. One does not consider the phase response and the other does. Both types of broadband reflectors operating at W-band were machined and measured to verify the numerical simulations.

Moduli of Parabolic Higgs Bundles and Atiyah Algebroids

DEFF Research Database (Denmark)

Logares, Marina; Martens, Johan

2010-01-01

In this paper we study the geometry of the moduli space of (non-strongly) parabolic Higgs bundles over a Riemann surface with marked points. We show that this space possesses a Poisson structure, extending the one on the dual of an Atiyah algebroid over the moduli space of parabolic vector bundle...

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

Science.gov (United States)

Feliciano-Cruz, Luisa I.

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

Ionospheric trough Model used for Telecommunication Purposes

International Nuclear Information System (INIS)

Rothkaehl, H.; Stanislawska, I.

1999-01-01

The mid-latitude trough is dynamical phenomena influenced the COST 251 area. Modelled parameters in COST 251 project are critically dependent on its location and magnitude. The particular importance to HF propagation assessments involving off-great-circle modes of incorporating a representation of the position of the trough is noted. ITU-R prediction maps (ITU-R, 1997) which are currently used in most international propagation assessments do not include this fact. (author)

Neutron spectrum in small iron pile surrounded by lead reflector

International Nuclear Information System (INIS)

Kimura, Itsuro; Hayashi, S.A.; Kobayashi, Katsuhei; Matsumura, Tetsuo; Nishihara, Hiroshi.

1978-01-01

In order to save the quantity of sample material, a possibility to assess group constants of a reactor material through measurement and analysis of neutron spectrum in a small sample pile surrounded by a reflector of heavy moderator, was investigated. As the sample and the reflector, we chose iron and lead, respectively. Although the time dispersion in moderation of neutrons was considerably prolonged by the lead reflector, this hardly interferes with the assessment of group constants. Theoretical calculation revealed that both the neutron flux spectrum and the sensitivity coefficient of group constants in an iron sphere, 35 cm in diameter surrounded by the lead reflector, 25 cm thick, were close to those of the bare iron sphere, 108 cm in diameter. The neutron spectra in a small iron pile surrounded by a lead reflector were experimentally obtained by the time-of-flight method with an electron linear accelerator and the result was compared with the predicted values. It could be confirmed that a small sample pile surrounded by a reflector, such as lead, was as useful as a much larger bulk pile for the assessment of group constants of a reactor material. (auth.)

Ultrabroadband Hybrid III-V/SOI Grating Reflector for On-chip Lasers

DEFF Research Database (Denmark)

Park, Gyeong Cheol; Taghizadeh, Alireza; Chung, Il-Sug

2016-01-01

We report on a new type of III-V/SOI grating reflector with a broad stopband of 350 nm. This reflector has promising prospects for applications in high-speed III-V/SOI vertical cavity lasers with an improved heat dissipation capability.......We report on a new type of III-V/SOI grating reflector with a broad stopband of 350 nm. This reflector has promising prospects for applications in high-speed III-V/SOI vertical cavity lasers with an improved heat dissipation capability....

Moduli space of Parabolic vector bundles over hyperelliptic curves

Indian Academy of Sciences (India)

27

This has been generalized for higher dimensional varieties by Maruyama ... Key words and phrases. Parabolic structure .... Let E be a vector bundle of rank r on X. Recall that a parabolic ..... Let us understand this picture geometrically. Let ω1 ...

The geometrical theory of diffraction for axially symmetric reflectors

DEFF Research Database (Denmark)

Rusch, W.; Sørensen, O.

1975-01-01

The geometrical theory of diffraction (GTD) (cf. [1], for example) may be applied advantageously to many axially symmetric reflector antenna geometries. The material in this communication presents analytical, computational, and experimental results for commonly encountered reflector geometries...

A compact representation of drawing movements with sequences of parabolic primitives.

Directory of Open Access Journals (Sweden)

Felix Polyakov

2009-07-01

Full Text Available Some studies suggest that complex arm movements in humans and monkeys may optimize several objective functions, while others claim that arm movements satisfy geometric constraints and are composed of elementary components. However, the ability to unify different constraints has remained an open question. The criterion for a maximally smooth (minimizing jerk motion is satisfied for parabolic trajectories having constant equi-affine speed, which thus comply with the geometric constraint known as the two-thirds power law. Here we empirically test the hypothesis that parabolic segments provide a compact representation of spontaneous drawing movements. Monkey scribblings performed during a period of practice were recorded. Practiced hand paths could be approximated well by relatively long parabolic segments. Following practice, the orientations and spatial locations of the fitted parabolic segments could be drawn from only 2-4 clusters, and there was less discrepancy between the fitted parabolic segments and the executed paths. This enabled us to show that well-practiced spontaneous scribbling movements can be represented as sequences ("words" of a small number of elementary parabolic primitives ("letters". A movement primitive can be defined as a movement entity that cannot be intentionally stopped before its completion. We found that in a well-trained monkey a movement was usually decelerated after receiving a reward, but it stopped only after the completion of a sequence composed of several parabolic segments. Piece-wise parabolic segments can be generated by applying affine geometric transformations to a single parabolic template. Thus, complex movements might be constructed by applying sequences of suitable geometric transformations to a few templates. Our findings therefore suggest that the motor system aims at achieving more parsimonious internal representations through practice, that parabolas serve as geometric primitives and that non

Convergence studies of deterministic methods for LWR explicit reflector methodology

International Nuclear Information System (INIS)

Canepa, S.; Hursin, M.; Ferroukhi, H.; Pautz, A.

2013-01-01

The standard approach in modem 3-D core simulators, employed either for steady-state or transient simulations, is to use Albedo coefficients or explicit reflectors at the core axial and radial boundaries. In the latter approach, few-group homogenized nuclear data are a priori produced with lattice transport codes using 2-D reflector models. Recently, the explicit reflector methodology of the deterministic CASMO-4/SIMULATE-3 code system was identified to potentially constitute one of the main sources of errors for core analyses of the Swiss operating LWRs, which are all belonging to GII design. Considering that some of the new GIII designs will rely on very different reflector concepts, a review and assessment of the reflector methodology for various LWR designs appeared as relevant. Therefore, the purpose of this paper is to first recall the concepts of the explicit reflector modelling approach as employed by CASMO/SIMULATE. Then, for selected reflector configurations representative of both GII and GUI designs, a benchmarking of the few-group nuclear data produced with the deterministic lattice code CASMO-4 and its successor CASMO-5, is conducted. On this basis, a convergence study with regards to geometrical requirements when using deterministic methods with 2-D homogenous models is conducted and the effect on the downstream 3-D core analysis accuracy is evaluated for a typical GII deflector design in order to assess the results against available plant measurements. (authors)

A Nonlinear Dynamic Model and Free Vibration Analysis of Deployable Mesh Reflectors

Science.gov (United States)

Shi, H.; Yang, B.; Thomson, M.; Fang, H.

2011-01-01

This paper presents a dynamic model of deployable mesh reflectors, in which geometric and material nonlinearities of such a space structure are fully described. Then, by linearization around an equilibrium configuration of the reflector structure, a linearized model is obtained. With this linearized model, the natural frequencies and mode shapes of a reflector can be computed. The nonlinear dynamic model of deployable mesh reflectors is verified by using commercial finite element software in numerical simulation. As shall be seen, the proposed nonlinear model is useful for shape (surface) control of deployable mesh reflectors under thermal loads.

A comparative Thermal Analysis of conventional parabolic receiver tube and Cavity model tube in a Solar Parabolic Concentrator

Science.gov (United States)

Arumugam, S.; Ramakrishna, P.; Sangavi, S.

2018-02-01

Improvements in heating technology with solar energy is gaining focus, especially solar parabolic collectors. Solar heating in conventional parabolic collectors is done with the help of radiation concentration on receiver tubes. Conventional receiver tubes are open to atmosphere and loose heat by ambient air currents. In order to reduce the convection losses and also to improve the aperture area, we designed a tube with cavity. This study is a comparative performance behaviour of conventional tube and cavity model tube. The performance formulae were derived for the cavity model based on conventional model. Reduction in overall heat loss coefficient was observed for cavity model, though collector heat removal factor and collector efficiency were nearly same for both models. Improvement in efficiency was also observed in the cavity model’s performance. The approach towards the design of a cavity model tube as the receiver tube in solar parabolic collectors gave improved results and proved as a good consideration.

Feasibility study of fusion breeding blanket concept employing graphite reflector

International Nuclear Information System (INIS)

Cho, Seungyon; Ahn, Mu-Young; Lee, Cheol Woo; Kim, Eung Seon; Park, Yi-Hyun; Lee, Youngmin; Lee, Dong Won

2015-01-01

Highlights: • A Helium-Cooled Ceramic Reflector (HCCR) breeding blanket concept adopts graphite as a reflector material by reducing the amount of beryllium multiplier. • Its feasibility was investigated in view point of the nuclear performance as well as material-related issues. • A nuclear analysis is performed under the fusion reactor condition to address the feasibility of graphite reflector in breeding blanket. • Also, the chemical stability of the graphite is investigated considering the chemical stability under accident conditions. • In conclusion, the adaptation of graphite reflector in breeding blanket is intrinsically safe and plausible under fusion reactor condition. - Abstract: To obtain high tritium breeding performance with limited blanket thickness, most of solid breeder blanket concepts employ a combination of lithium ceramic as a breeder and beryllium as a multiplier. In this case, considering that huge amount of beryllium are needed in fusion power plants, its handling difficulty and cost can be a major factor to be accounted for commercial use. Korea has proposed a Helium-Cooled Ceramic Reflector (HCCR) breeding blanket concept relevant to fusion power plants. Here, graphite is used as a reflector material by reducing the amount of beryllium multiplier. Its feasibility has been investigated in view point of the nuclear performance as well as material-related issues. In this paper, a nuclear analysis is performed under the fusion reactor condition to address the feasibility of graphite reflector in breeding blanket, considering tritium breeding capability and neutron shielding and activation aspects. Also, the chemical stability of the graphite is investigated considering the chemical stability under accident conditions, resulting in that the adaptation of graphite reflector in breeding blanket is intrinsically safe and plausible under fusion reactor condition.

Feasibility study of fusion breeding blanket concept employing graphite reflector

Energy Technology Data Exchange (ETDEWEB)

Cho, Seungyon, E-mail: sycho@nfri.re.kr [National Fusion Research Institute, Daejeon (Korea, Republic of); Ahn, Mu-Young [National Fusion Research Institute, Daejeon (Korea, Republic of); Lee, Cheol Woo; Kim, Eung Seon [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Park, Yi-Hyun; Lee, Youngmin [National Fusion Research Institute, Daejeon (Korea, Republic of); Lee, Dong Won [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

2015-10-15

Highlights: • A Helium-Cooled Ceramic Reflector (HCCR) breeding blanket concept adopts graphite as a reflector material by reducing the amount of beryllium multiplier. • Its feasibility was investigated in view point of the nuclear performance as well as material-related issues. • A nuclear analysis is performed under the fusion reactor condition to address the feasibility of graphite reflector in breeding blanket. • Also, the chemical stability of the graphite is investigated considering the chemical stability under accident conditions. • In conclusion, the adaptation of graphite reflector in breeding blanket is intrinsically safe and plausible under fusion reactor condition. - Abstract: To obtain high tritium breeding performance with limited blanket thickness, most of solid breeder blanket concepts employ a combination of lithium ceramic as a breeder and beryllium as a multiplier. In this case, considering that huge amount of beryllium are needed in fusion power plants, its handling difficulty and cost can be a major factor to be accounted for commercial use. Korea has proposed a Helium-Cooled Ceramic Reflector (HCCR) breeding blanket concept relevant to fusion power plants. Here, graphite is used as a reflector material by reducing the amount of beryllium multiplier. Its feasibility has been investigated in view point of the nuclear performance as well as material-related issues. In this paper, a nuclear analysis is performed under the fusion reactor condition to address the feasibility of graphite reflector in breeding blanket, considering tritium breeding capability and neutron shielding and activation aspects. Also, the chemical stability of the graphite is investigated considering the chemical stability under accident conditions, resulting in that the adaptation of graphite reflector in breeding blanket is intrinsically safe and plausible under fusion reactor condition.

Isotopic feature and uranium dating of the volcanic rocks in the Okinawa Trough

Institute of Scientific and Technical Information of China (English)

无

2006-01-01

Volcanic rocks from the northern and middle Okinawa Trough were dated by uranium-series dating method. Differential fractions using magnetic procedure were designed to separate samples. New report on the ages and isotopic data of rocks in the northern trough (especially black pumice) was discussed. Based on the uranium dates and Sr-Nd isotopic ratio, magmatic evolution process of the Okinawa Trough was noted. Firstly, there have been wide silicic volcanic activities in the Okinawa Trough from late Pleistocene to present, and the volcanic rocks can be divided into three subgroups. Secondly, magma generally came from PREMA source area under the Okinawa Trough. Magmatic evolution in the northern trough was similar to the middle, but different to the south. Finally, volcanic activities indicated that opening of the southern Okinawa Trough did not happen due to the collision between Luson Arc and Eurasian Plate until the early Pleistocene.

Environmental Controls and Eco-geomorphic Interactions of the Barchan-to-parabolic Dune Stabilisation and the Parabolic-to-barchan Dune Reactivation

Science.gov (United States)

Yan, Na; Baas, Andreas

2015-04-01

Parabolic dunes are one of a few common aeolian landforms which are highly controlled by eco-geomorphic interactions. Parabolic dunes, on the one hand, can be developed from highly mobile dune landforms, barchans for instance, in an ameliorated vegetation condition; or on the other hand, they can be reactivated and transformed back into mobile dunes due to vegetation deterioration. The fundamental mechanisms and eco-geomorphic interactions controlling both dune transformations remain poorly understood. To bridge the gap between complex processes involved in dune transformations on a relatively long temporal scale and real world monitoring records on a very limited temporal scale, this research has extended the DECAL model to incorporate 'dynamic' growth functions and the different 'growth' of perennial shrubs between growing and non-growing seasons, informed by field measurements and remote sensing analysis, to explore environmental controls and eco-geomorphic interactions of both types of dune transformation. A non-dimensional 'dune stabilising index' is proposed to capture the interactions between environmental controls (i.e. the capabilities of vegetation to withstand wind erosion and sand burial, the sandy substratum thickness, the height of the initial dune, and the sand transport potential), and establish the linkage between these controls and the geometry of a stabilising dune. An example demonstrates how to use the power-law relationship between the dune stabilising index and the normalised migration distance to assist in extrapolating the historical trajectories of transforming dunes. The modelling results also show that a slight increase in vegetation cover of an initial parabolic dune can significantly increase the reactivation threshold of climatic impact (both drought stress and wind strength) required to reactivate a stabilising parabolic dune into a barchan. Four eco-geomorphic interaction zones that govern a barchan-to-parabolic dune transformation

Finite-time blow-up for quasilinear degenerate Keller-Segel systems of parabolic-parabolic type

Science.gov (United States)

Hashira, Takahiro; Ishida, Sachiko; Yokota, Tomomi

2018-05-01

This paper deals with the quasilinear degenerate Keller-Segel systems of parabolic-parabolic type in a ball of RN (N ≥ 2). In the case of non-degenerate diffusion, Cieślak-Stinner [3,4] proved that if q > m + 2/N, where m denotes the intensity of diffusion and q denotes the nonlinearity, then there exist initial data such that the corresponding solution blows up in finite time. As to the case of degenerate diffusion, it is known that a solution blows up if q > m + 2/N (see Ishida-Yokota [13]); however, whether the blow-up time is finite or infinite has been unknown. This paper gives an answer to the unsolved problem. Indeed, the finite-time blow-up of energy solutions is established when q > m + 2/N.

Steady-state thermal analysis of an innovative receiver for linear Fresnel reflectors

International Nuclear Information System (INIS)

Abbas, R.; Muñoz, J.; Martínez-Val, J.M.

2012-01-01

Highlights: ► An innovative multitube receiver for linear Fresnel reflectors is presented. ► Higher performance is achieved thanks to better heat transfer conditions. ► A wide range of designs that maximize efficiency for different conditions is found. ► Heat transfer fluid inlet temperature must be lower for low radiation intensities. ► Fresnel performance may be close to trough collectors, with lower costs. -- Abstract: The study of the performance of an innovative receiver for linear Fresnel reflectors is carried out in this paper, and the results are analyzed with a physics perspective of the process. The receiver consists of a bundle of tubes parallel to the mirror arrays, resulting on a smaller cross section for the same receiver width as the number of tubes increases, due to the diminution of their diameter. This implies higher heat carrier fluid speeds, and thus, a more effective heat transfer process, although it conveys higher pumping power as well. Mass flow is optimized for different tubes diameters, different impinging radiation intensities and different fluid inlet temperatures. It is found that the best receiver design, namely the tubes diameter that maximizes the exergetic efficiency for given working conditions, is similar for the cases studied. There is a range of tubes diameters that imply similar efficiencies, which can drive to capital cost reduction thanks to the flexibility of design. In addition, the length of the receiver is also optimized, and it is observed that the optimal length is similar for the working conditions considered. As a result of this study, it is found that this innovative receiver provides an optimum design for the whole day, even though impinging radiation intensity varies notably. Thermal features of this type of receiver could be the base of a new generation of concentrated solar power plants with a great potential for cost reduction, because of the simplicity of the system and the lower weigh of the

Flux form Semi-Lagrangian methods for parabolic problems

Directory of Open Access Journals (Sweden)

Bonaventura Luca

2016-09-01

Full Text Available A semi-Lagrangian method for parabolic problems is proposed, that extends previous work by the authors to achieve a fully conservative, flux-form discretization of linear and nonlinear diffusion equations. A basic consistency and stability analysis is proposed. Numerical examples validate the proposed method and display its potential for consistent semi-Lagrangian discretization of advection diffusion and nonlinear parabolic problems.

Hybrid solar collector using nonimaging optics and photovoltaic components

Science.gov (United States)

Winston, Roland; Yablonovitch, Eli; Jiang, Lun; Widyolar, Bennett K.; Abdelhamid, Mahmoud; Scranton, Gregg; Cygan, David; Kozlov, Alexandr

2015-08-01

The project team of University of California at Merced (UC-M), Gas Technology Institute, and Dr. Eli Yablonovitch of University of California at Berkeley developed a novel hybrid concentrated solar photovoltaic thermal (PV/T) collector using nonimaging optics and world record single-junction Gallium arsenide (GaAs) PV components integrated with particle laden gas as thermal transfer and storage media, to simultaneously generate electricity and high temperature dispatchable heat. The collector transforms a parabolic trough, commonly used in CSP plants, into an integrated spectrum-splitting device. This places a spectrum-sensitive topping element on a secondary reflector that is registered to the thermal collection loop. The secondary reflector transmits higher energy photons for PV topping while diverting the remaining lower energy photons to the thermal media, achieving temperatures of around 400°C even under partial utilization of the solar spectrum. The collector uses the spectral selectivity property of Gallium arsenide (GaAs) cells to maximize the exergy output of the system, resulting in an estimated exergy efficiency of 48%. The thermal media is composed of fine particles of high melting point material in an inert gas that increases heat transfer and effectively stores excess heat in hot particles for later on-demand use.

ANALISIS PERBANDINGAN OUTPUT DAYA LISTRIK PANEL SURYA SISTEM TRACKING DENGAN SOLAR REFLECTOR

Directory of Open Access Journals (Sweden)

I B Kd Surya Negara

2016-03-01

Full Text Available Indonesia merupakan negara beriklim tropis yang memiliki intensitas radiasi matahari yang sangat besar dan intensitas radiasi tersebut berpotensi untuk dikembangkan menjadi Pembangkit Listrik Tenaga Surya. Efisiensi dari panel surya saat ini masih perlu pertimbangan lebih lanjut. Efisiensi panel surya yang rendah ini, berpengaruh pada hasil output daya listrik yang dihasilkan. Upaya untuk meningkatkan output daya listrik panel surya, yaitu dengan sistem tracking dan solar reflector. Penelitian ini bertujuan untuk mengetahui output daya listrik yang lebih maksimal. Metode dalam penelitian ini menggunakan sistem tracking yang pergerakannya berdasarkan waktu dan menggunakan solar reflector dengan cermin datar dan sudut reflector yang berbeda. Hasil dari perbandingan sistem tracking dengan solar reflector yaitu solar reflector menghasilkan output daya listrik lebih besar dibandingan dengan sistem tracking, dimana solar reflector menghasilkan output daya listrik sebesar 0.1224 Watt dan sistem tracking sebesar 0.1136 Watt.

Enhancing the stepped solar still performance using internal and external reflectors

International Nuclear Information System (INIS)

Omara, Z.M.; Kabeel, A.E.; Younes, M.M.

2014-01-01

Highlights: • Stepped solar still with internal and external reflectors have been investigated. • The productivity of the modified stepped solar still is higher than conventional by 103%. • The productivity of stepped still with external mirror is higher than that for conventional still by 88%. - Abstract: The performance of stepped solar still with internal and external reflectors have been investigated in the current study. The reflectors are used to enhance energy input to the stepped still. The influence of internal and external (top and bottom) reflectors on the performance of the stepped solar still is investigated. A comparison between modified stepped solar still and conventional solar still is carried out to evaluate the developed desalination system performance under the same climate conditions. The results indicated that, during experimentation the productivity of the modified stepped solar still with internal and external (top and bottom) reflectors is higher than that for conventional still approximately by 125%. In this case the estimated cost of 1 l of distillate for stepped still with reflectors and conventional solar stills is approximately 0.031$ and 0.049$, respectively

Highly accurate photogrammetric measurements of the Planck reflectors

Science.gov (United States)

Amiri Parian, Jafar; Gruen, Armin; Cozzani, Alessandro

2017-11-01

The Planck mission of the European Space Agency (ESA) is designed to image the anisotropies of the Cosmic Background Radiation Field over the whole sky. To achieve this aim, sophisticated reflectors are used as part of the Planck telescope receiving system. The system consists of secondary and primary reflectors which are sections of two different ellipsoids of revolution with mean diameters of 1 and 1.6 meters. Deformations of the reflectors which influence the optical parameters and the gain of receiving signals are investigated in vacuum and at very low temperatures. For this investigation, among the various high accuracy measurement techniques, photogrammetry was selected. With respect to the photogrammetric measurements, special considerations had to be taken into account in design steps, measurement arrangement and data processing to achieve very high accuracies. The determinability of additional parameters of the camera under the given network configuration, datum definition, reliability and precision issues as well as workspace limits and propagating errors from different sources are considered. We have designed an optimal photogrammetric network by heuristic simulation for the flight model of the primary and the secondary reflectors with relative precisions better than 1:1000'000 and 1:400'000 to achieve the requested accuracies. A least squares best fit ellipsoid method was developed to determine the optical parameters of the reflectors. In this paper we will report about the procedures, the network design and the results of real measurements.

Beyond Wires and Seeds: Reflector-guided Breast Lesion Localization and Excision.

Science.gov (United States)

Mango, Victoria L; Wynn, Ralph T; Feldman, Sheldon; Friedlander, Lauren; Desperito, Elise; Patel, Sejal N; Gomberawalla, Ameer; Ha, Richard

2017-08-01

Purpose To evaluate outcomes of Savi Scout (Cianna Medical, Aliso Viejo, Calif) reflector-guided localization and excision of breast lesions by analyzing reflector placement, localization, and removal, along with target excision and rates of repeat excision (referred to as re-excision). Materials and Methods A single-institution retrospective review of 100 women who underwent breast lesion localization and excision by using the Savi Scout surgical guidance system from June 2015 to May 2016 was performed. By using image guidance 0-8 days before surgery, 123 nonradioactive, infrared-activated, electromagnetic wave reflectors were percutaneously inserted adjacent to or within 111 breast targets. Twenty patients had two or three reflectors placed for bracketing or for localizing multiple lesions, and when ipsilateral, they were placed as close as 2.6 cm apart. Target and reflector were localized intraoperatively by one of two breast surgeons who used a handpiece that emitted infrared light and electromagnetic waves. Radiographs of the specimen and pathologic analysis helped verify target and reflector removal. Target to reflector distance was measured on the mammogram and radiograph of the specimen, and reflector depth was measured on the mammogram. Pathologic analysis was reviewed. Re-excision rates and complications were recorded. By using statistics software, descriptive statistics were generated with 95% confidence intervals (CIs) calculated. Results By using sonographic (40 of 123; 32.5%; 95% CI: 24.9%, 41.2%) or mammographic (83 of 123; 67.5%; 95% CI: 58.8% 75.1%) guidance, 123 (100%; 95% CI: 96.4%, 100%) reflectors were placed. Mean mammographic target to reflector distance was 0.3 cm. All 123 (100%; 95% CI: 96.4%, 100%) targets and reflectors were excised. Pathologic analysis yielded 54 of 110 malignancies (49.1%; 95% CI: 39.9%, 58.3%; average, 1.0 cm; range, 0.1-5 cm), 32 high-risk lesions (29.1%; 95% CI: 21.4%, 38.2%), and 24 benign lesions (21.8%; 95% CI

Performance Improvement of Solar Water Stills by Using Reflectors

Directory of Open Access Journals (Sweden)

Humphrey Hamusonde Maambo

2016-09-01

Full Text Available The lack of safe and clean drinking water sources is one of the problems faced in most rural communities in Zambia. Water in these communities is mostly obtained from shallow wells and rivers. However, this water might be potentially contaminated with harmful substances such as pathogenic bacteria and therefore, unsafe for drinking. Solar water distillation represents an important alternative to palliate problems of fresh water shortages. Solar water stills can be used to eliminate harmful substances from contaminated water by treating it using free solar energy before it can be consumed. Therefore, there is a need to improve solar still performance to produce a greater quantity of safe drinking water. One possible method to improve performance is through adding reflectors to solar stills. Reflectors improve performance by increasing the quantity of distillate by about 22.3 % at a water depth of 15 mm and about 2 9% at a water depth of 10 mm when compared to the distillate produced from a still without reflectors. The water produced using solar stills with reflectors was tested and adhered to World Health Organization (WHO drinking water standards. This implies that solar distillation with reflectors could be adopted at a larger scale to produce safer drinking water at a reduced cost.

Weak Lensing by Galaxy Troughs in DES Science Verification Data

Energy Technology Data Exchange (ETDEWEB)

Gruen, D. [Ludwig Maximilian Univ., Munich (Germany); Max Planck Inst. for Extraterrestrial Physics, Garching (Germany). et al.

2015-09-29

We measure the weak lensing shear around galaxy troughs, i.e. the radial alignment of background galaxies relative to underdensities in projections of the foreground galaxy field over a wide range of redshift in Science Verification data from the Dark Energy Survey. Our detection of the shear signal is highly significant (10σ–15σ for the smallest angular scales) for troughs with the redshift range z ϵ [0.2, 0.5] of the projected galaxy field and angular diameters of 10 arcmin…1°. These measurements probe the connection between the galaxy, matter density, and convergence fields. By assuming galaxies are biased tracers of the matter density with Poissonian noise, we find agreement of our measurements with predictions in a fiducial Λ cold dark matter model. Furthermore, the prediction for the lensing signal on large trough scales is virtually independent of the details of the underlying model for the connection of galaxies and matter. Our comparison of the shear around troughs with that around cylinders with large galaxy counts is consistent with a symmetry between galaxy and matter over- and underdensities. In addition, we measure the two-point angular correlation of troughs with galaxies which, in contrast to the lensing signal, is sensitive to galaxy bias on all scales. Finally, the lensing signal of troughs and their clustering with galaxies is therefore a promising probe of the statistical properties of matter underdensities and their connection to the galaxy field.

SAFARI-1 research reactor beryllium reflector element replacement, management and relocation

International Nuclear Information System (INIS)

Kock, Marisa De; Vlok, Jwh; Steynberg, B.J.

2012-01-01

The beryllium (Be) reflector elements of the SAFARI-1 Research Reactor were replaced in October 2011 as part of the Ageing Management Programme of the reactor. After more than three million MWh of operation over a period of 47 years, core reloading became more difficult due to the geometric deformation of the beryllium reflector elements. During the replacement of the reflector elements, criticality and reactivity worth experiments were performed and found to compare favorably with calculated values. A Beryllium Management Programme was established at SAFARI-1 to identify and apply effective and appropriate actions and practices for managing the ageing of the new beryllium reflector elements. This will provide timely detection and mitigation of ageing mechanisms relevant to beryllium reflector elements, supporting the life extension of these elements. These actions and practices include monitoring of the tritium levels in the primary water, calculating and measuring the fluxes within the beryllium reflector positions, measuring the straightness of the elements to track geometric deformation and visually inspecting the reflector elements for crack formation. Acceptance criteria indicating the end of life of the elements were established. These criteria take into account the smallest gap that could exist between elements, sudden changes in the tritium levels and formation of cracks. All the data obtained through the Beryllium Management Programme are recorded in a database. Additional benefits gained through a Beryllium Management Programme are the availability of a complete irradiation history of the beryllium reflector elements at any point in time and the establishment of a knowledge base to assists in the understanding of the behavior of the beryllium reflector elements in an irradiation environment. Straightness baseline measurements of the new beryllium reflector elements were performed with a beryllium straightness measurement tool, designed at SAFARI-1. The

SAFARI-1 research reactor beryllium reflector element replacement, management and relocation

Energy Technology Data Exchange (ETDEWEB)

Kock, Marisa De; Vlok, Jwh; Steynberg, B J [South Africa Atomic Energy Corporation (Necsa) (South Africa)

2012-03-15

The beryllium (Be) reflector elements of the SAFARI-1 Research Reactor were replaced in October 2011 as part of the Ageing Management Programme of the reactor. After more than three million MWh of operation over a period of 47 years, core reloading became more difficult due to the geometric deformation of the beryllium reflector elements. During the replacement of the reflector elements, criticality and reactivity worth experiments were performed and found to compare favorably with calculated values. A Beryllium Management Programme was established at SAFARI-1 to identify and apply effective and appropriate actions and practices for managing the ageing of the new beryllium reflector elements. This will provide timely detection and mitigation of ageing mechanisms relevant to beryllium reflector elements, supporting the life extension of these elements. These actions and practices include monitoring of the tritium levels in the primary water, calculating and measuring the fluxes within the beryllium reflector positions, measuring the straightness of the elements to track geometric deformation and visually inspecting the reflector elements for crack formation. Acceptance criteria indicating the end of life of the elements were established. These criteria take into account the smallest gap that could exist between elements, sudden changes in the tritium levels and formation of cracks. All the data obtained through the Beryllium Management Programme are recorded in a database. Additional benefits gained through a Beryllium Management Programme are the availability of a complete irradiation history of the beryllium reflector elements at any point in time and the establishment of a knowledge base to assists in the understanding of the behavior of the beryllium reflector elements in an irradiation environment. Straightness baseline measurements of the new beryllium reflector elements were performed with a beryllium straightness measurement tool, designed at SAFARI-1. The

Photoionization cross section in a spherical quantum dot: Effects of some parabolic confining electric potentials

Directory of Open Access Journals (Sweden)

M. Tshipa

2017-12-01

Full Text Available A theoretical investigation of the effects of spatial variation of confining electric potential on photoionization cross section (PCS in a spherical quantum dot is presented. The potential profiles considered here are the shifted parabolic potential and the inverse lateral shifted parabolic potential compared with the well-studied parabolic potential. The primary findings are that parabolic potential and the inverse lateral shifted parabolic potential blue shift the peaks of the PCS while the shifted parabolic potential causes a red shift.

Slovakia: Proposal of movable reflector for fast reactor design

International Nuclear Information System (INIS)

Vrban, B.

2015-01-01

In fast reactors a larger migration area leading to a significant leak of neutrons can be observed because especially the transport cross-sections are in general smaller as compared to light water reactors. The utilization of a moveable reflector system in conjunction with dedicated safety control rods can increase the ability of accident managing due to enhanced escaping neutrons which otherwise would be reflected back into the fuel zone. The paper demonstrates the possibility of better controlling the transient reactor by additionally moving selected reflector subassemblies equipped with the neutron trap. The main purpose of the analysis of the Gas-cooled Fast Reactor (GFR) presented in the full paper is investigation of the kinetic parameters and of the control and reflector rod worth, as well as optimization of the parts used for partial reflector withdrawal. The results found in this study may serve for future design improvements of other designs such as the liquid metal cooled fast reactors

Hermitian-Einstein metrics on parabolic stable bundles

International Nuclear Information System (INIS)

Li Jiayu; Narasimhan, M.S.

1995-12-01

Let M-bar be a compact complex manifold of complex dimension two with a smooth Kaehler metric and D a smooth divisor on M-bar. If E is a rank 2 holomorphic vector bundle on M-bar with a stable parabolic structure along D, we prove the existence of a metric on E' = E module MbarD (compatible with the parabolic structure) which is Hermitian-Einstein with respect to the restriction of Kaehler metric of M-barD. A converse is also proved. (author). 24 refs

Enhanced light absorption of silicon solar cells with dielectric nanostructured back reflector

Science.gov (United States)

Ren, Rui; Zhong, Zheng

2018-06-01

This paper investigates the light absorption property of nanostructured dielectric reflectors in silicon thin film solar cells using numerical simulation. Flat thin film solar cell with ZnO nanostructured back reflector can produce comparable photocurrent to the control model with Ag nanostructured back reflector. Furthermore, when it is integrated with nano-pillar surface decoration, a photocurrent density of 29.5 mA/cm2 can be achieved, demonstrating a photocurrent enhancement of 5% as compared to the model with Ag nanostructured back reflector.

Paleocene Pacific Plate reorganization mirrored in formation of the Suvarov Trough, Manihiki Plateau

Science.gov (United States)

Pietsch, Ricarda; Uenzelmann-Neben, Gabriele

2016-10-01

The Suvarov Trough is a graben structure that deviates from the Danger Islands Troughs within the Manihiki Plateau, a Large Igneous Province (LIP) located in the Central Pacific. New high-resolution seismic reflection data provide evidence that the graben formed in two phases during the Paleocene (65-45 Ma). In a first phase extension occurred in southwestward direction, pulling apart the northern part of the Suvarov Trough and a parallel trending unnamed trough. In a second phase a change of extensional force direction occurred from southwest to west-northwest, forming the southern part of the Suvarov Trough that extends onto the High Plateau. The formation of the Suvarov Trough is accompanied by a series of normal fault systems that apparently formed simultaneously. Comparing the seismic results to existing Pacific paleo strain reconstructions, the timing of increased strain and local deformation direction fits well to our findings. We thus suggest that the multiple strike directions of the Suvarov Trough represent an extensional structure that was caused by the major, stepwise Pacific Plate reorganization during the Paleocene.

Structural-electromagnetic bidirectional coupling analysis of space large film reflector antennas

Science.gov (United States)

Zhang, Xinghua; Zhang, Shuxin; Cheng, ZhengAi; Duan, Baoyan; Yang, Chen; Li, Meng; Hou, Xinbin; Li, Xun

2017-10-01

As used for energy transmission, a space large film reflector antenna (SLFRA) is characterized by large size and enduring high power density. The structural flexibility and the microwave radiation pressure (MRP) will lead to the phenomenon of structural-electromagnetic bidirectional coupling (SEBC). In this paper, the SEBC model of SLFRA is presented, then the deformation induced by the MRP and the corresponding far field pattern deterioration are simulated. Results show that, the direction of the MRP is identical to the normal of the reflector surface, and the magnitude is proportional to the power density and the square of cosine incident angle. For a typical cosine function distributed electric field, the MRP is a square of cosine distributed across the diameter. The maximum deflections of SLFRA linearly increase with the increasing microwave power densities and the square of the reflector diameters, and vary inversely with the film thicknesses. When the reflector diameter becomes 100 m large and the microwave power density exceeds 102 W/cm2, the gain loss of the 6.3 μm-thick reflector goes beyond 0.75 dB. When the MRP-induced deflection degrades the reflector performance, the SEBC should be taken into account.

Linear and quasi-linear equations of parabolic type

CERN Document Server

Ladyženskaja, O A; Ural′ceva, N N; Uralceva, N N

1968-01-01

Equations of parabolic type are encountered in many areas of mathematics and mathematical physics, and those encountered most frequently are linear and quasi-linear parabolic equations of the second order. In this volume, boundary value problems for such equations are studied from two points of view: solvability, unique or otherwise, and the effect of smoothness properties of the functions entering the initial and boundary conditions on the smoothness of the solutions.

Reflector and Protections in a Sodium-cooled Fast Reactor: Modelling and Optimization

Science.gov (United States)

Blanchet, David; Fontaine, Bruno

2017-09-01

The ASTRID project (Advanced Sodium Technological Reactor for Industrial Demonstration) is a Generation IV nuclear reactor concept under development in France [1]. In this frame, studies are underway to optimize radial reflectors and protections. Considering radial protections made in natural boron carbide, this study is conducted to assess the neutronic performances of the MgO as the reference choice for reflector material, in comparison with other possible materials including a more conventional stainless steel. The analysis is based upon a simplified 1-D and 2-D deterministic modelling of the reactor, providing simplified interfaces between core, reflector and protections. Such models allow examining detailed reaction rate distributions; they also provide physical insights into local spectral effects occurring at the Core-Reflector and at the Reflector-Protection interfaces.

Patient-reported non-adherence and immunosuppressant trough levels are associated with rejection after renal transplantation.

Science.gov (United States)

Scheel, Jennifer; Reber, Sandra; Stoessel, Lisa; Waldmann, Elisabeth; Jank, Sabine; Eckardt, Kai-Uwe; Grundmann, Franziska; Vitinius, Frank; de Zwaan, Martina; Bertram, Anna; Erim, Yesim

2017-03-29

Different measures of non-adherence to immunosuppressant (IS) medication have been found to be associated with rejection episodes after successful transplantation. The aim of the current study was to investigate whether graft rejection after renal transplantation is associated with patient-reported IS medication non-adherence and IS trough level variables (IS trough level variability and percentage of sub-therapeutic IS trough levels). Patient-reported non-adherence, IS trough level variability, percentage of sub-therapeutic IS trough levels, and acute biopsy-proven late allograft rejections were assessed in 267 adult renal transplant recipients who were ≥12 months post-transplantation. The rate of rejection was 13.5%. IS trough level variability, percentage of sub-therapeutic IS trough levels as well as patient-reported non-adherence were all significantly and positively associated with rejection, but not with each other. Logistic regression analyses revealed that only the percentage of sub-therapeutic IS trough levels and age at transplantation remained significantly associated with rejection. Particularly, the percentage of sub-therapeutic IS trough levels is associated with acute rejections after kidney transplantation whereas IS trough level variability and patient-reported non-adherence seem to be of subordinate importance. Patient-reported non-adherence and IS trough level variables were not correlated; thus, non-adherence should always be measured in a multi-methodological approach. Further research concerning the best combination of non-adherence measures is needed.

Describing Quadratic Cremer Point Polynomials by Parabolic Perturbations

DEFF Research Database (Denmark)

Sørensen, Dan Erik Krarup

1996-01-01

We describe two infinite order parabolic perturbation proceduresyielding quadratic polynomials having a Cremer fixed point. The main ideais to obtain the polynomial as the limit of repeated parabolic perturbations.The basic tool at each step is to control the behaviour of certain externalrays.......Polynomials of the Cremer type correspond to parameters at the boundary of ahyperbolic component of the Mandelbrot set. In this paper we concentrate onthe main cardioid component. We investigate the differences between two-sided(i.e. alternating) and one-sided parabolic perturbations.In the two-sided case, we prove...... the existence of polynomials having an explicitlygiven external ray accumulating both at the Cremer point and at its non-periodicpreimage. We think of the Julia set as containing a "topologists double comb".In the one-sided case we prove a weaker result: the existence of polynomials havingan explicitly given...

Seasonal variation and solar activity dependence of the quiet-time ionospheric trough

Science.gov (United States)

Ishida, T.; Ogawa, Y.; Kadokura, A.; Hiraki, Y.; Häggström, I.

2014-08-01

We have conducted a statistical analysis of the ionospheric F region trough, focusing on its seasonal variation and solar activity dependence under geomagnetically quiet and moderate conditions, using plasma parameter data obtained via Common Program 3 observations performed by the European Incoherent Scatter (EISCAT) radar between 1982 and 2011. We have confirmed that there is a major difference in frictional heating between the high- and low-latitude sides of the EISCAT field of view (FOV) at ~73°0'N-60°5'N (geomagnetic latitude) at an altitude of 325 km, which is associated with trough formation. Our statistical results show that the high-latitude and midlatitude troughs occur on the high- and low-latitude sides of the FOV, respectively. Seasonal variations indicate that dissociative recombination accompanied by frictional heating is a main cause of trough formation in sunlit regions. During summer, therefore, the occurrence rate is maintained at 80-90% in the postmidnight high-latitude region owing to frictional heating by eastward return flow. Solar activity dependence on trough formation indicates that field-aligned currents modulate the occurrence rate of the trough during the winter and equinox seasons. In addition, the trough becomes deeper via dissociative recombination caused by an increased ion temperature with F10.7, at least in the equinox and summer seasons but not in winter.

Probabilistic tsunami hazard assessment considering time-lag of seismic event on Nankai trough

International Nuclear Information System (INIS)

Sugino, Hideharu; Sakagami, Masaharu; Ebisawa, Katsumi; Korenaga, Mariko

2011-01-01

In the area in front of Nankai trough, tsunami wave height may increase if tsunamis attacking from some wave sources overlap because of time-lag of seismic event on Nankai trough. To evaluation tsunami risk of the important facilities located in front of Nankai trough, we proposed the probabilistic tsunami hazard assessment considering uncertainty on time-lag of seismic event on Nankai trough and we evaluated the influence that the time-lag gave to tsunami hazard at the some representative points. (author)

Mechatronic Prototype of Parabolic Solar Tracker.

Science.gov (United States)

Morón, Carlos; Díaz, Jorge Pablo; Ferrández, Daniel; Ramos, Mari Paz

2016-06-15

In the last 30 years numerous attempts have been made to improve the efficiency of the parabolic collectors in the electric power production, although most of the studies have focused on the industrial production of thermoelectric power. This research focuses on the application of this concentrating solar thermal power in the unexplored field of building construction. To that end, a mechatronic prototype of a hybrid paraboloidal and cylindrical-parabolic tracker based on the Arduido technology has been designed. The prototype is able to measure meteorological data autonomously in order to quantify the energy potential of any location. In this way, it is possible to reliably model real commercial equipment behavior before its deployment in buildings and single family houses.

Experimentation of a Solar Water Heater with Integrated Storage Tank

International Nuclear Information System (INIS)

Elhmidi, I; Frikha, N; Chaouchi, B; Gabsi, S

2009-01-01

An integrated collector storage (ICS) solar water heater was constructed in 2004 and studied its optical and thermal performance. It was revealed that it has some thermal shortcomings of thermal performances. The ICS system consists of one cylindrical horizontal tank properly mounted in a stationary symmetrical Compound Parabolic Concentrating (CPC) reflector trough. The main objective was to delimit the causes of these deficiencies and trying to diagnose them. A rigorous experimentation of the solar water heater has been done over its daily energetic output as well as the evolution of the nocturnal thermal losses. In fact, three successive days, including nights, of operation have permitted to obtain diagrams describing the variations of mean temperature in the tank and the thermal loss coefficient during night of our installation. The experimental results, compared with those obtained by simulation, showed a perfecting of thermal performances of system which approach from those of other models introduced on the international market

Numerical performance of the parabolized ADM (PADM) formulation of General Relativity

OpenAIRE

Paschalidis, Vasileios; Hansen, Jakob; Khokhlov, Alexei

2007-01-01

In a recent paper the first coauthor presented a new parabolic extension (PADM) of the standard 3+1 Arnowitt, Deser, Misner formulation of the equations of general relativity. By parabolizing first-order ADM in a certain way, the PADM formulation turns it into a mixed hyperbolic - second-order parabolic, well-posed system. The surface of constraints of PADM becomes a local attractor for all solutions and all possible well-posed gauge conditions. This paper describes a numerical implementation...

Resource assessment of methane hydrate in the eastern Nankai Trough, Japan

Energy Technology Data Exchange (ETDEWEB)

Fujii, T.; Saeki, T.; Kobayashi, T.; Inamori, T.; Hayashi, M.; Takano, O.; Takayama, T.; Kawasaki, T.; Nagakubo, S.; Nakamizu, M.; Yokoi, K. [Japan Oil, Gas and Metals National Corp., Mihama-ku, Chiba (Japan). Technology and Research Center

2008-07-01

This study investigated the methane hydrate (MH) in the Nankai Trough offshore Japan as a potential natural gas resource. The resource assessment of MH was determined from the Ministry of Economy, Trade and Industry (METI) exploratory test wells Tokai-oki to Kumano-nada. Logging-while-drilling (LWD) campaigns were launched at 16 sites, coring at 4 sites and wirelogging at 2 sites. This study used high resolution 2D/3D seismic data and introduced a new concept for the MH concentrated zone and applied it to resource assessment. MH bearing layers in the survey area were classified into 2 categories, notably MH concentrated zones and MH bearing layers other than relatively thin, low saturated MH layers. The total amount of methane gas in place was estimated to be 40 tcf as Pmean value (10 tcf as P90, 82 tcf as P10). More than 10 prospective MH concentrated zones were extracted. They were characterized by high resistivity well logs, strong seismic reflectors, high p-wave interval velocity and turbidite deposits delineated by sedimentary facies analysis. The total gas in place for MH concentrated zones was estimated to be 20 tcf (half of the total amount) as Pmean value. Sensitivity analysis revealed that the net-to-gross ratio and methane pore saturation have higher sensitivity than other parameters. As such, they are important for further detail analysis. 22 refs., 3 tabs., 9 figs.

Ellipsoidal reflector for measuring oto-acoustic emissions

DEFF Research Database (Denmark)

Epp, Bastian; Pulkki, Ville; Heiskanen, Vesa

2014-01-01

A truncated prolate ellipsoidal reflector having the ear canal of a listener at one focal point and large- diaphragm low-noise microphone at the other focal point is proposed for free-field recordings of oto-acoustic emissions. A prototype reflector consisting of three pieces is presented, which...... enables measuring the response of the system with different truncations. The response of the system is measured with a miniature loud- speaker, and proof-of-concept measurements of oto-acoustic emissions are presented. The effect of truncation and other physical parameters to the performance of the system...

Main ionospheric trough in the daytime sector studied on the basis of vertical sounding data

Energy Technology Data Exchange (ETDEWEB)

Benkova, N.P.; Kozlov, E.F.; Mozhaev, A.M.; Osipov, N.K.; Samorokin, N.I.

1980-09-01

Data for 1969-1973 are used to study the displacement of the main ionospheric trough during daytime magnetic storms. The depth of the trough and electron density gradients on the sides of the trough are determined. The trough is found to move in a southeasterly direction during daytime storms. The results agree with theoretical conclusions that explain the formation of the trough by the collective transport of ionospheric plasma in a sunward direction.

Compact range for variable-zone measurements

Science.gov (United States)

Burnside, Walter D.; Rudduck, Roger C.; Yu, Jiunn S.

1988-08-02

A compact range for testing antennas or radar targets includes a source for directing energy along a feedline toward a parabolic reflector. The reflected wave is a spherical wave with a radius dependent on the distance of the source from the focal point of the reflector.

Distribution of analytes over TXRF reflectors

International Nuclear Information System (INIS)

Bernasconi, G.; Tajani, A.

2000-01-01

One of the most frequently used methods for trace element analysis in TXRF involves the evaporation of small amounts of aqueous solutions over flat reflectors. This method has the advantage of in-situ pre-concentration of the analytes, which together with the low background due to the total reflection in the substrate leads to excellent detection limits and high signal to noise ratio. The spiking of the liquid sample with an internal standard provides also a simple way to achieve multielemental quantitative analysis. However the elements are not homogeneously distributed over the reflector after the liquid phase has been evaporated. This distribution may be different for the unknown elements and the internal standards and may influence the accuracy of the quantitative results. In this presentation we used μ-XRF techniques to map this distribution. Small (20 μl) drops of a binary solution were evaporated over silicon reflectors and then mapped using a focused X-ray beam with about 100 μm resolution. A typical ring structure showing some differences in the distribution of both elements has been observed. One of the reflectors was also measured in a TXRF setup turning it at different angles with reference to the X-ray beam (with constant incidence and take-off angles) and variations of the intensity relation between both elements were measured. This work shows the influence of the sample distribution and proposes methods to evaluate it. In order to assess the limitations of the accuracy of the results due to the sample distribution more measurements would be necessary, however due to the small size of typical TXRF samples and the tight geometry of TXRF setups the influence of the sample distribution is not large. (author)

Characterization of a Bifacial Photovoltaic Panel Integrated with External Diffuse and Semimirror Type Reflectors

Directory of Open Access Journals (Sweden)

P. Ooshaksaraei

2013-01-01

Full Text Available Silicon wafer accounts for almost one-half the cost of a photovoltaic (PV panel. A bifacial silicon solar cell is attractive due to its potential of enhancing power generation from the same silicon wafer in comparison with a conventional monofacial solar cell. The bifacial PV cell is able to capture solar radiation by back surface. This ability requires a suitable reflector appropriately oriented and separated from the cell’s rear surface. In order to optimize the bifacial solar cell performance with respect to an external back surface reflector, diffuse and semimirror reflectors were investigated at various angles and separations from the back surface. A simple bifacial solar panel, consisting of four monocrystalline Si solar cells, was designed and built. Reflection from the rear surface was provided by an extended semimirror and a white-painted diffuse reflector. Maximum power generation was observed at 30° with respect to ground for the semimirror reflector and 10° for diffuse reflector at an optimized reflector-panel separation of 115 mm. Output power enhancement of 20% and 15% from semimirror and diffuse reflectors, respectively, were observed. This loss from diffuse reflector is attributed to scattering of light beyond the rear surface capture cross-section of the bifacial solar panel.

Determination of source terms in a degenerate parabolic equation

International Nuclear Information System (INIS)

Cannarsa, P; Tort, J; Yamamoto, M

2010-01-01

In this paper, we prove Lipschitz stability results for inverse source problems relative to parabolic equations. We use the method introduced by Imanuvilov and Yamamoto in 1998 based on Carleman estimates. What is new here is that we study a class of one-dimensional degenerate parabolic equations. In our model, the diffusion coefficient vanishes at one extreme point of the domain. Instead of the classical Carleman estimates obtained by Fursikov and Imanuvilov for non degenerate equations, we use and extend some recent Carleman estimates for degenerate equations obtained by Cannarsa, Martinez and Vancostenoble. Finally, we obtain Lipschitz stability results in inverse source problems for our class of degenerate parabolic equations both in the case of a boundary observation and in the case of a locally distributed observation

Interaction Potential between Parabolic Rotator and an Outside Particle

Directory of Open Access Journals (Sweden)

Dan Wang

2014-01-01

Full Text Available At micro/nanoscale, the interaction potential between parabolic rotator and a particle located outside the rotator is studied on the basis of the negative exponential pair potential 1/Rn between particles. Similar to two-dimensional curved surfaces, we confirm that the potential of the three-dimensional parabolic rotator and outside particle can also be expressed as a unified form of curvatures; that is, it can be written as the function of curvatures. Furthermore, we verify that the driving forces acting on the particle may be induced by the highly curved micro/nano-parabolic rotator. Curvatures and the gradient of curvatures are the essential elements forming the driving forces. Through the idealized numerical experiments, the accuracy of the curvature-based potential is preliminarily proved.

Parabolic solar concentrators with fully illuminated inverted V absorber; Coletor concentrador parabolico composto (CPC) com absorvedor V invertido completamente iluminado

Energy Technology Data Exchange (ETDEWEB)

Brandao, Braulio Bezerra

2004-10-01

Although literature on parabolic solar concentrators is numerically considerable, there are no publications regarding CPC with fully illuminate, inverted V absorber, nothing is mentioned about optical and geometric properties or, collected thermal energy. This type of solar concentrator exists in the international market, but with little known divulgence of its properties, perhaps explained because of industrial protection. In the first part of this work, the equations that define the concentrator cavity curve and its optical and geometric properties were deduced and studied in detail, by a numeric simulation program, elaborated in Meatball language. Additionally, optimization studies about the viability of the construction of this collector were carried out, relative truncation effects (the elimination of the upper part of the cavity) on the optics and geometric properties and the annual energy generated by the equipment. For the CPC concentrator collectors with fully illuminated inverted V absorbers and ideal (without truncation) it was concluded that in the configuration in which the angle of angular acceptance of the CPC is equal to the apex angle of the absorber, there occurs a minimum perimeter of the reflector cavity, when the nominal concentration and the size of the absorber are constant. Regarding the CPC concentrator collectors fully illuminated with inverted V absorber and with optimized truncation, it is shown, for a concentrator of 1.2 concentration, a good related reflector surface length and opening, and a mean number of reflections and generated thermal energy that this occurs for concentrators arising from concentrators with acceptance angles among 33.75 up to 45.58 degrees. (author)

The Planck Telescope reflectors

Science.gov (United States)

Stute, Thomas

2004-09-01

The mechanical division of EADS-Astrium GmbH, Friedrichshafen is currently engaged with the development, manufacturing and testing of the advanced dimensionally stable composite reflectors for the ESA satellite borne telescope Planck. The objective of the ESA mission Planck is to analyse the first light that filled the universe, the cosmic microwave background radiation. Under contract of the Danish Space Research Institute and ESA EADS-Astrium GmbH is developing the all CFRP primary and secondary reflectors for the 1.5-metre telescope which is the main instrument of the Planck satellite. The operational frequency ranges from to 25 GHz to 1000 GHz. The demanding high contour accuracy and surface roughness requirements are met. The design provides the extreme dimensional stability required by the cryogenic operational environment at around 40 K. The elliptical off-axis reflectors display a classical lightweight sandwich design with CFRP core and facesheets. Isostatic mounts provide the interfaces to the telescope structure. Protected VDA provides the reflecting surface. The manufacturing is performed at the Friedrichshafen premises of EADS-Space Transportation GmbH, the former Dornier composite workshops. Advanced manufacturing technologies like true angle lay-up by CNC fibre placement and filament winding are utilized. The protected coating is applied at the CAHA facilities at the Calar Alto Observatory, Spain. The exhaustive environmental testing is performed at the facilities of IABG, Munich (mechanical testing) and for the cryo-optical tests at CSL Liege. The project is in advanced state with both Qualification Models being under environmental testing. The flight models will be delivered in 2004. The paper gives an overview over the requirements and the main structural features how these requirements are met. Special production aspects and available test results are reported.

Baseline seismic survey for the 2nd offshore methane hydrate production test in the Eastern Nankai Trough

Science.gov (United States)

Teranishi, Y.; Inamori, T.; Kobayashi, T.; Fujii, T.; Saeki, T.; Takahashi, H.; Kobayashi, F.

2017-12-01

JOGMEC carries out seismic monitoring surveys before and after the 2nd offshore methane hydrate (MH) production test in the Eastern Nankai Trough and evaluates MH dissociation behavior from the time-lapse seismic response. In 2016, JOGMEC deployed Ocean Bottom Cable (OBC) system provided by OCC in the Daini Atsumi Knoll with water depths of 900-1100 m. The main challenge of the seismic survey was to optimize the cable layout for ensuring an effective time-lapse seismic detectability while overcoming the following two issues: 1. OBC receiver lines were limited to only two lines. It was predicted that the imaging of shallow reflectors would suffer from lack of continuity and resolution due to this limitation of receiver lines. 2. The seafloor and shallow sedimentary layers including monitoring target are dipping to the Northwest direction. It was predicted that the refection points would laterally shift to up-dip direction (Southeast direction). In order to understand the impact of the issues above, the seismic survey was designed with elastic wave field simulation. The reflection seismic survey for baseline data was conducted in August 2016. A total of 70 receiver stations distributed along one cable were deployed successfully and a total of 9952 shots were fired. After the baseline seismic survey, the hydrophone and geophone vertical component datasets were processed as outlined below: designaturing, denoising, surface consistent deconvolution and surface consistent amplitude correction. High-frequency imaging with Reverse Time Migration (RTM) was introduced to these data sets. Improvements in imaging from the RTM are remarkable compared to the Kirchhoff migration and the existing Pre-stack time migration with 3D marine surface seismic data obtained and processed in 2002, especially in the following parts. The MH concentrated zone which has complex structures. Below the Bottom Simulating Reflector (BSR) which is present as a impedance-contrast boundary

Effect of phototherapy with alumunium foil reflectors on neonatal hyperbilirubinemia

Directory of Open Access Journals (Sweden)

Tony Ijong Dachlan

2015-03-01

Full Text Available Background Neonatal hyperbilirubinemia (NH is one of the most common problems in neonates, but it can be treated with blue light phototherapy. Developing countries with limited medical equipment and funds have difficulty providing effective phototherapy to treat NH, leading to increased risk of bilirubin encephalopathy. Phototherapy with white reflecting curtains can decrease the duration of phototherapy needed to reduce bilirubin levels. Objective To compare the duration of phototherapy needed in neonates with NH who underwent phototherapy with and without aluminum foil reflectors. Methods This open clinical trial was conducted from July to August 2013 at Dr. Hasan Sadikin Hospital, Bandung, Indonesia. The inclusion criteria were term neonates with uncomplicated NH presenting in their first week of life. Subjects were randomized into two groups, those who received phototherapy with or without aluminum foil reflectors. Serum bilirubin is taken at 12th, 24th, 48th hours, then every 24 hours if needed until phototherapy can be stopped according to American Academy of Pediatrics guidelines. The outcome measured was the duration of phototherapy using survival analysis. The difference between the two groups was tested by Gehan method. Results Seventy newborns who fulfilled the inclusion criteria and had similar characteristics were randomized into two groups. The duration of phototherapy needed was significantly less in the group with aluminum foil reflectors than in the group without reflectors [72 vs. 96 hours, respectively, (P<0.01]. Conclusion The required duration of phototherapy with aluminum foil reflectors is significantly less than that of phototherapy without reflectors, in neonates with NH.

Numerical Study of Concentration Characteristics of Linear Fresnel Reflector System

International Nuclear Information System (INIS)

Lee, Hyun Jin; Kim, Jong Kyu; Lee, Sang Nam

2015-01-01

In this study, we numerically investigated the concentration characteristics of a linear Fresnel reflector system that can drive a solar thermal absorption refrigeration system to be installed in Saudi Arabia. Using an optical modeling program based on the Monte Carlo ray-tracing method, we simulated the concentrated solar flux, concentration efficiency, and concentrated solar energy on four representative days of the year - the vernal equinox, summer solstice, autumnal equinox, and winter solstice. Except the winter solstice, the concentrations were approximately steady from 9 AM to 15 PM, and the concentration efficiencies exceed 70%. Moreover, the maximum solar flux around the solar receiver center changes only within the range of 13.0 - 14.6 kW/m 2 . When we investigated the effects of the receiver installation height, reflector width, and reflector gap, the optimal receiver installation height was found to be 5 m. A smaller reflector width had a greater concentration efficiency. However, the design of the reflector width should be based on the capacity of the refrigeration system because it dominantly affects the concentrated solar energy. The present study was an essential prerequisite for thermal analyses of the solar receiver. Thus, an optical-thermal integration study in the future will assist with the performance prediction and design of the entire system

Numerical Study of Concentration Characteristics of Linear Fresnel Reflector System

Energy Technology Data Exchange (ETDEWEB)

Lee, Hyun Jin [Kookmin Univ., Seoul (Korea, Republic of); Kim, Jong Kyu; Lee, Sang Nam [Korea Institute of Energy Research, Daejeon (Korea, Republic of)

2015-12-15

In this study, we numerically investigated the concentration characteristics of a linear Fresnel reflector system that can drive a solar thermal absorption refrigeration system to be installed in Saudi Arabia. Using an optical modeling program based on the Monte Carlo ray-tracing method, we simulated the concentrated solar flux, concentration efficiency, and concentrated solar energy on four representative days of the year - the vernal equinox, summer solstice, autumnal equinox, and winter solstice. Except the winter solstice, the concentrations were approximately steady from 9 AM to 15 PM, and the concentration efficiencies exceed 70%. Moreover, the maximum solar flux around the solar receiver center changes only within the range of 13.0 - 14.6 kW/m{sup 2}. When we investigated the effects of the receiver installation height, reflector width, and reflector gap, the optimal receiver installation height was found to be 5 m. A smaller reflector width had a greater concentration efficiency. However, the design of the reflector width should be based on the capacity of the refrigeration system because it dominantly affects the concentrated solar energy. The present study was an essential prerequisite for thermal analyses of the solar receiver. Thus, an optical-thermal integration study in the future will assist with the performance prediction and design of the entire system.

The effects of stainless steel radial reflector on core reactivity for small modular reactor

Energy Technology Data Exchange (ETDEWEB)

Kang, Jung Kil, E-mail: jkkang@email.kings.ac.kr; Hah, Chang Joo, E-mail: changhah@kings.ac.kr [KINGS, 658-91, Haemaji-ro, Seosaeng-myeon, Ulju-gun, Ulsan, 689-882 (Korea, Republic of); Cho, Sung Ju, E-mail: sungju@knfc.co.kr; Seong, Ki Bong, E-mail: kbseong@knfc.co.kr [KNFC, Daedeok-daero 989beon-gil, Yuseong-gu, Daejeon, 305-353 (Korea, Republic of)

2016-01-22

Commercial PWR core is surrounded by a radial reflector, which consists of a baffle and water. Radial reflector is designed to reflect neutron back into the core region to improve the neutron efficiency of the reactor and to protect the reactor vessels from the embrittling effects caused by irradiation during power operation. Reflector also helps to flatten the neutron flux and power distributions in the reactor core. The conceptual nuclear design for boron-free small modular reactor (SMR) under development in Korea requires to have the cycle length of 4∼5 years, rated power of 180 MWth and enrichment less than 5 w/o. The aim of this paper is to analyze the effects of stainless steel radial reflector on the performance of the SMR using UO{sub 2} fuels. Three types of reflectors such as water, water/stainless steel 304 mixture and stainless steel 304 are selected to investigate the effect on core reactivity. Additionally, the thickness of stainless steel and double layer reflector type are also investigated. CASMO-4/SIMULATE-3 code system is used for this analysis. The results of analysis show that single layer stainless steel reflector is the most efficient reflector.

Mechatronic Prototype of Parabolic Solar Tracker

Directory of Open Access Journals (Sweden)

Carlos Morón

2016-06-01

Full Text Available In the last 30 years numerous attempts have been made to improve the efficiency of the parabolic collectors in the electric power production, although most of the studies have focused on the industrial production of thermoelectric power. This research focuses on the application of this concentrating solar thermal power in the unexplored field of building construction. To that end, a mechatronic prototype of a hybrid paraboloidal and cylindrical-parabolic tracker based on the Arduido technology has been designed. The prototype is able to measure meteorological data autonomously in order to quantify the energy potential of any location. In this way, it is possible to reliably model real commercial equipment behavior before its deployment in buildings and single family houses.

Nanofocusing parabolic refractive x-ray lenses

International Nuclear Information System (INIS)

Schroer, C.G.; Kuhlmann, M.; Hunger, U.T.; Guenzler, T.F.; Kurapova, O.; Feste, S.; Frehse, F.; Lengeler, B.; Drakopoulos, M.; Somogyi, A.; Simionovici, A.S.; Snigirev, A.; Snigireva, I.; Schug, C.; Schroeder, W.H.

2003-01-01

Parabolic refractive x-ray lenses with short focal distance can generate intensive hard x-ray microbeams with lateral extensions in the 100 nm range even at a 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 380 nm by 210 nm at 25 keV in a distance of 42 m from the synchrotron radiation source. Using diamond as the lens material, microbeams with a lateral size down to 20 nm and below are conceivable in the energy range from 10 to 100 keV

Main-Reflector Manufacturing Technology for the Deep Space Optical Communications Ground Station

Science.gov (United States)

Britcliffe, M. J.; Hoppe, D. J.

2001-01-01

The Deep Space Network (DSN) has plans to develop a 10-m-diameter optical communications receiving station. The system uses the direct detection technique, which has much different requirements from a typical astronomical telescope. The receiver must operate in daylight and nighttime conditions. This imposes special requirements on the optical system to reject stray light from the Sun and other sources. One of the biggest challenges is designing a main-reflector surface that meets these requirements and can be produced at a reasonable cost. The requirements for the performance of the reflector are presented. To date, an aspherical primary reflector has been assumed. A reflector with a spherical reflector has a major cost advantage over an aspherical design, with no sacrifice in performance. A survey of current manufacturing techniques for optical mirrors of this type was performed. Techniques including solid glass, lightweight glass, diamond-turned aluminum, and composite mirrors were investigated.

A figure control sensor for the Large Deployable Reflector (LDR)

Science.gov (United States)

Bartman, R.; Dubovitsky, S.

1988-01-01

A sensing and control system is required to maintain high optical figure quality in a segmented reflector. Upon detecting a deviation of the segmented surface from its ideal form, the system drives segment mounted actuators to realign the individual segments and thereby return the surface to its intended figure. When the reflector is in use, a set of figure sensors will determine positions of a number of points on the back surface of each of the reflector's segments, each sensor being assigned to a single point. By measuring the positional deviations of these points from previously established nominal values, the figure sensors provide the control system with the information required to maintain the reflector's optical figure. The optical lever, multiple wavelength interferometer, and electronic capacitive sensor, the most promising technologies for the development of the figure sensor, are illustrated. It is concluded that to select a particular implementation of the figure sensors, performance requirement will be refined and relevant technologies investigated further.

Computer aided FEA simulation of EN45A parabolic leaf spring

Directory of Open Access Journals (Sweden)

Krishan Kumar

2013-04-01

Full Text Available This paper describes computer aided finite element analysis of parabolic leaf spring. The present work is an improvement in design of EN45A parabolic leaf spring used by a light commercial automotive vehicle. Development of a leaf spring is a long process which requires lots of test to validate the design and manufacturing variables. A three-layer parabolic leaf spring of EN45A has been taken for this work. The thickness of leaves varies from center to the outer side following a parabolic pattern. These leaf springs are designed to become lighter, but also provide a much improved ride to the vehicle through a reduction on interleaf friction. The CAD modeling of parabolic leaf spring has been done in CATIA V5 and for analysis the model is imported in ANSYS-11 workbench. The finite element analysis (FEA of the leaf spring has been carried out by initially discretizing the model into finite number of elements and nodes and then applying the necessary boundary conditions. Maximum displacement, directional displacement, equivalent stress and weight of the assembly are the output targets of this analysis for comparison & validation of the work.

Solar thermal power: the seamless solar link to the conventional power world

International Nuclear Information System (INIS)

Geyer, Michael; Quaschning, Volker

2000-01-01

This article focuses on solar thermal power generation and describes two solar thermal power concepts, namely, the parabolic trough or solar farm, and the solar central receiver or power tower. Details are given of grid-connected parabolic trough power plants in California and recent developments in collector design and absorber tubes, and the operation of power tower plants with different heat transfer media. Market issues are discussed, and solar thermal power projects under development, and application for support for solar thermal power projects under the Global Environment Facility's Operational Programme by Egypt, India, Iran, Mexico and Morocco are reported

Measurement of the stored energy in the NRX reactor reflector graphite

Energy Technology Data Exchange (ETDEWEB)

Hilton, H. B.; Larson, E. A.G.

1959-07-15

With the co-operation of workers at Windscale and Harwell, whose assistance is hereby gratefully acknowledged, the stored energy content of the inner reflector graphite of NRX has been measured. Measurements made at three different elevations and at different positions through the reflector show that there is, at present, no danger to NRX from an accidental release of the energy. The energy stored in the reflector in 1958 is less by a factor five to ten than the stored energy as measured in 1953. It appears that there has been a continual release of stored energy since 1954 when, after the rehabilitation, the maximum power was raised to 40 MW. Additional thermocouples have been installed in the inner reflector, and future stored energy measurements are being scheduled. (author)

Concurrent immunomodulator therapy is associated with higher adalimumab trough levels during scheduled maintenance therapy.

Science.gov (United States)

Bond, Ashley; Dodd, Susanna; Fisher, Gareth; Skouras, Thomas; Subramanian, Sreedhar

2017-02-01

Combination therapy with infliximab and immunomodulators is superior to monotherapy, resulting in better outcomes and higher trough levels of infliximab. The role of concurrent immunomodulatory therapy on adalimumab trough levels has not been adequately investigated. We evaluated the impact of concomitant immunomodulation on adalimumab trough levels in patients on scheduled maintenance therapy. We conducted a prospective observational, cross-sectional study of all inflammatory bowel disease patients on maintenance therapy who had adalimumab trough levels measured between January 2013 and January 2016. Drug level and anti-drug antibody measurements were performed on sera using a solid phase assay. Pairwise comparison of means was used to compare trough levels in patients with and without concomitant immune modulator therapy. In total, 79 patients were included. Twenty-three patients (29.1%) were on weekly dosing whereas 56 (70.9%) were on alternate weeks. Median adalimumab trough levels were comparable in patients with and without clinical remission (6.8 μg/ml (IQR 5.6-8.1) versus 6.7 μg/ml (IQR 3.9-8.1), respectively. Patients with an elevated faecal calprotectin >250 μg/g had lower adalimumab trough levels (median 6.7, IQR 3.9-8) compared to patients with faecal calprotectin <250 μg/g (median 7.7, IQR 6.1-8.1) though this did not achieve statistical significance (p = .062). Median adalimumab trough levels among patients on concurrent immunomodulators was 7.2 μg/ml (IQR 5.7-8.1) compared to those not on concurrent immunomodulator, 6.1 μg/ml (IQR 2.7-7.7, p = .0297). Adalimumab trough levels were significantly higher in patients on concurrent immunomodulators during maintenance therapy. There was a trend towards a lower adalimumab trough level in patients with elevated calprotectin.

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

Science.gov (United States)

Ashyralyev, Allaberen; Hanalyev, Asker

2014-01-01

The nonlocal boundary value problem for the parabolic differential equation v'(t) + A(t)v(t) = f(t) (0 ≤ t ≤ T), v(0) = v(λ) + φ, 0 exact estimates in Hölder norms for the solution of two nonlocal boundary value problems for parabolic equations with dependent coefficients are established.

Efficiency improvement of flat plate solar collector using reflector

Directory of Open Access Journals (Sweden)

Himangshu Bhowmik

2017-11-01

Full Text Available Solar collectors are the main components of a solar heating system. The collectors collect the sun’s energy, transform this radiation into heat, and then transfer this heat into a fluid, water or air, which has many household or industrial applications. This paper introduces a new technology to improve the performance of the solar thermal collectors. The solar reflector used here with the solar collector to increase the reflectivity of the collector. Thus, the reflector concentrates both direct and diffuse radiation of the sun toward the collector. To maximize the intensity of incident radiation, the reflector was allowed to change its angle with daytime. The radiations coming from the sun’s energy were converted into heat, and then this heat was transferred to the collector fluid, water. A prototype of a solar water heating system was constructed and obtained the improvement of the collector efficiency around 10% by using the reflector. Thus, the present solar water heating systems having the best thermal performance compared to the available systems.

Variation of reflected radiation from all reflectors of a flat plate solar collector during a year

International Nuclear Information System (INIS)

Pavlović, Zoran T.; Kostić, Ljiljana T.

2015-01-01

In this paper the impact of flat plate reflectors (bottom, top, left and right reflectors) made of Al, on total solar radiation on a solar collector during a day time over a whole year is analyzed. An analytical model for determining optimum tilt angles of a collector and reflectors for any point on the Earth is proposed. Variations of reflectors' optimal inclination angles with changes of the collector's optimal tilt angle during the year are also calculated. Optimal inclination angles of the reflectors for the South directed solar collector are calculated and compared to experimental data. It is shown that optimal inclination of the bottom reflector is the lowest in December and the highest in June, while for the top reflector the lowest value is in June and the highest value is in December. On the other hand, optimal inclination of the left and right side reflectors for optimum tilt angle of the collector does not change during the year and it is 66°. It is found that intensity of the solar radiation on the collector increases for about 80% in the summer period (June–September) by using optimally inclined reflectors, in comparison to the collector without reflectors. - Highlights: • The impacts of flat plate reflectors on solar radiation on the collector are given. • The results of the optimal inclinations of reflectors during the year are shown. • The solar radiation on the collector with reflectors is 80% higher in the summer. • This model may be applied on thermal, PV, PV/T and energy harvesting systems

Development of a New core/reflector model for coarse-mesh nodal methods

International Nuclear Information System (INIS)

Pogosbekyan, Leonid; Cho, Jin Young; Kim, Young Il; Kim, Young Jin; Joo, Hyung Kuk; Chang, Moon Hee.

1997-10-01

This work presents two approaches for reflector simulation in coarse-mesh nodal methods. The first approach is called Interface Matrix Technique (IMT), which simulates the baffle as a banishingly thin layer having the property of reflection and transmission. We applied this technique within the frame of AFEN (Analytic Function Expansion Nodal) method, and developed the AFEN-IM (Interface Matrix) method. AFEN-IM method shows 1.24% and 0.42 % in maximum and RMS (Root Mean Square) assemblywise power error for ZION-1 benchmark problem. The second approach is L-shaped reflector homogenization method. This method is based on the integral response conservation along the L-shaped core-reflector interface. The reference reflector response is calculated from 2-dimensional spectral calculation and the response of the homogenized reflector is derived from the one-node 2-dimensional AFEN problem solution. This method shows 5 times better accuracy than the 1-dimensional homogenization technique in the assemblywise power. Also, the concept of shroud/reflector homogenization for hexagonal core have been developed. The 1-dimensional spectral calculation was used for the determination of 2 group cross sections. The essence of homogenization concept consists in the calculation of equivalent shroud width, which preserve albedo for the fast neutrons in 2-dimensional reflector. This method shows a relative error less than 0.42% in assemblywise power and a difference of 9x10 -5 in multiplication factor for full-core model. (author). 9 refs., 3 tabs., 28 figs

Coercive properties of elliptic-parabolic operator

International Nuclear Information System (INIS)

Duong Min Duc.

1987-06-01

Using a generalized Poincare inequality, we study the coercive properties of a class of elliptic-parabolic partial differential equations, which contains many degenerate elliptic equations considered by the other authors. (author). 16 refs

Identifying Reflectors in Seismic Images via Statistic and Syntactic Methods

Directory of Open Access Journals (Sweden)

Carlos A. Perez

2010-04-01

Full Text Available In geologic interpretation of seismic reflection data, accurate identification of reflectors is the foremost step to ensure proper subsurface structural definition. Reflector information, along with other data sets, is a key factor to predict the presence of hydrocarbons. In this work, mathematic and pattern recognition theory was adapted to design two statistical and two syntactic algorithms which constitute a tool in semiautomatic reflector identification. The interpretive power of these four schemes was evaluated in terms of prediction accuracy and computational speed. Among these, the semblance method was confirmed to render the greatest accuracy and speed. Syntactic methods offer an interesting alternative due to their inherently structural search method.

Numerical form-finding method for large mesh reflectors with elastic rim trusses

Science.gov (United States)

Yang, Dongwu; Zhang, Yiqun; Li, Peng; Du, Jingli

2018-06-01

Traditional methods for designing a mesh reflector usually treat the rim truss as rigid. Due to large aperture, light weight and high accuracy requirements on spaceborne reflectors, the rim truss deformation is indeed not negligible. In order to design a cable net with asymmetric boundaries for the front and rear nets, a cable-net form-finding method is firstly introduced. Then, the form-finding method is embedded into an iterative approach for designing a mesh reflector considering the elasticity of the supporting rim truss. By iterations on form-findings of the cable-net based on the updated boundary conditions due to the rim truss deformation, a mesh reflector with a fairly uniform tension distribution in its equilibrium state could be finally designed. Applications on offset mesh reflectors with both circular and elliptical rim trusses are illustrated. The numerical results show the effectiveness of the proposed approach and that a circular rim truss is more stable than an elliptical rim truss.

Mineralogy and geological significance of hydrothermal deposits from the Okinawa Trough

Science.gov (United States)

Zhang, Xia; Zhai, Shikui; Yu, Zenghui; Wang, Shujie; Cai, Zongwei

2018-04-01

The study of hydrothermal deposits in the Okinawa Trough can help us to uncover the hydrothermal mineralization characteristics in the back-arc basin during the early expanding stage. Mineralogy and geological significance of hydrothermal deposits from both the middle and southern trough are studied in this paper. First of all, using optical microscope to confirm the mineral compositions, characteristics of crystal shape, paragenetic relationship and minerals crystallization order. Then the minerals chemical composition were analyzed in virtue of electron microprobe. On these basis, the paragenetic sequence and the mineralization characteristics of the hydrothermal deposits were discussed. The results show that the hydrothermal deposit from the mid-Okinawa Trough belongs to Zn-Cu-rich type, consisting dominantly of sulfide minerals such as sphalerite, chalcopyrite, pyrite, etc. The minerals crystallization order is first generation pyrite(PyI)-sphalerite-chalcopyrite-galena-second generation pyrite(PyII)-amorphous silica. While the deposit from the southern Okinawa Trough is Ba-Zn-Pb-rich type mainly composing of barite, sphalerite, galena, etc. The minerals crystallization order is barite-pyrite-sphalerite-tetrahedrite-galena-chalcopyrite-amorphous silica. Hydrothermal fluid temperature in the mid-Okinawa Trough undergoes a process from high to low, which is high up to 350 °C in the early stage, but decreasing gradually with the evolution of hydrothermal fluid. On the contrary, the hydrothermal activity in the southern Okinawa Trough is low temperature dominated, but the mineralization environment is unstable and the fluid temperature changes drastically during the period of hydrothermal activity.

Selection of lamp reflector construction and fishing time of lift net

Directory of Open Access Journals (Sweden)

Gondo Puspito

2017-06-01

Full Text Available This study aimed to determine lift net’s lamp reflector construction which is able to give highest weight on catch and determine the best fishing time. Three lamp reflector constructions were made of cylinder shape for one construction and cone shape with opening angle α = 62° and 90° for two others. The dimension (øR × HR for each reflector are 30 × 37 (cm, 40 × 18 (cm and 40 × 39.62 (cm. Each lamp reflector was being operated by 1 lift net for 15 nights. Total fishing operations were twice per night within interval 07.00–12.00 PM and 00.00–05.00 AM. Results of the catch gave 2 schools of fish which were plankton feeders and predators. Plankton feeders included anchovy Stolephorus spp. 477 kg, mackerel (Rastrelliger spp. 1934 kg, and malayan half (Decapterus sp. 15.5 kg. Predators consisted of hairtail (Trichiurus sp. 982 kg, yellowstrip scad (Selaroides spp. 29 kg, and giant trevally (Caranx sp. 26.3 kg. The lift net which operated lamp reflector of α = 90° has the highest catch of 2,307.8 kg, while the lamp reflector of α = 62° has 1895 kg of catch. The one with cylinder shape has 1261 kg of catch.

Amplitude versus offset analysis to marine seismic data acquired in Nankai Trough, offshore Japan where methane hydrate exists

Science.gov (United States)

Hato, M.; Inamori, T.; Matsuoka, T.; Shimizu, S.

2003-04-01

Occurrence of methane hydrates in the Nankai Trough, located off the south-eastern coast of Japan, was confirmed by the exploratory test well drilling conducted by Japan’s Ministry of International Trade and Industry in 1999. Confirmation of methane hydrate has given so big impact to the Japan's future energy strategy and scientific and technological interest was derived from the information of the coring and logging results at the well. Following the above results, Japan National Oil Corporation (JNOC) launched the national project, named as MH21, for establishing the technology of methane hydrate exploration and related technologies such as production and development. As one of the research project for evaluating the total amount of the methane hydrate, Amplitude versus Offset (AVO) was applied to the seismic data acquired in the Nankai Trough area. The main purpose of the AVO application is to evaluate the validity of delineation of methane hydrate-bearing zones. Since methane hydrate is thought to accompany with free-gas in general just below the methane hydrate-bearing zones, the AVO has a possibility of describing the presence of free-gas. The free-gas is thought to be located just below the base of methane hydrate stability zone which is characterized by the Bottom Simulating Reflectors (BSRs) on the seismic section. In this sense, AVO technology, which was developed as gas delineation tools, can be utilized for methane hydrate exploration. The result of AVO analysis clearly shows gas-related anomaly below the BSRs. Appearance of the AVO anomaly has so wide variety. Some of the anomalies might not correspond to the free-gas existence, however, some of them may show free-gas. We are now going to develop methodology to clearly discriminate free-gas from non-gas zone by integrating various types of seismic methods such as seismic inversion and seismic attribute analysis.

Simultaneous delivery of electron beam therapy and ultrasound hyperthermia using scanning reflectors: a feasibility study

International Nuclear Information System (INIS)

Moros, Eduardo G.; Straube, William L.; Klein, Eric E.; Yousaf, Muhammed; Myerson, Robert J.

1995-01-01

Purpose: The feasibility of simultaneously delivering external electron beam radiation and superficial hyperthermia using a scanning ultrasound reflector-array system (SURAS) was experimentally investigated and demonstrated. Methods and Materials: A new system uses a scanning reflector to distribute the acoustic energy from a planar ultrasound array over the surface of the target volume. External photon/electron beams can be concurrently delivered with hyperthermia by irradiating through the scanning reflectors. That is, this system enables the acoustic waves and the radiation beams to enter the target volume from the same direction. Reflectors were constructed of air-equivalent materials for maximum acoustic reflection and minimum radiation attenuation. Acoustically, the air reflectors were compared to brass reflectors (assumed ideal) for reflectivity and specular quality using several single transducers ranging in frequency from 0.68 to 4.8 MHz. The relative reflectivity was determined from acoustic power measurements using a force-balance technique. The specular quality was assessed by comparing the acoustic pressure fields reflected by air reflectors with those reflected by brass reflectors. Also, acoustic pressure fields generated by a SURAS prototype for two different arrays (2.24 and 4.5 MHz) were measured to investigate field distribution variations as a function of the distance separating the array and the scanning reflector. All pressure fields were measured with a hydrophone in a degassed water tank. Finally, to determine the effect of the air reflectors on electron dose distributions, these were measured using film in a water-equivalent solid phantom after passage of a 20 MeV electron beam through the SURAS. These measurements were performed with the reflector scanning continuously across the electron beam and at rest within the electron beam. Results: The measurements performed using single ultrasound transducers showed that the air reflectors had

Use of a Parabolic Microphone to Detect Hidden Subjects in Search and Rescue.

Science.gov (United States)

Bowditch, Nathaniel L; Searing, Stanley K; Thomas, Jeffrey A; Thompson, Peggy K; Tubis, Jacqueline N; Bowditch, Sylvia P

2018-03-01

This study compares a parabolic microphone to unaided hearing in detecting and comprehending hidden callers at ranges of 322 to 2510 m. Eight subjects were placed 322 to 2510 m away from a central listening point. The subjects were concealed, and their calling volume was calibrated. In random order, subjects were asked to call the name of a state for 5 minutes. Listeners with parabolic microphones and others with unaided hearing recorded the direction of the call (detection) and name of the state (comprehension). The parabolic microphone was superior to unaided hearing in both detecting subjects and comprehending their calls, with an effect size (Cohen's d) of 1.58 for detection and 1.55 for comprehension. For each of the 8 hidden subjects, there were 24 detection attempts with the parabolic microphone and 54 to 60 attempts by unaided listeners. At the longer distances (1529-2510 m), the parabolic microphone was better at detecting callers (83% vs 51%; P<0.00001 by χ 2 ) and comprehension (57% vs 12%; P<0.00001). At the shorter distances (322-1190 m), the parabolic microphone offered advantages in detection (100% vs 83%; P=0.000023) and comprehension (86% vs 51%; P<0.00001), although not as pronounced as at the longer distances. Use of a 66-cm (26-inch) parabolic microphone significantly improved detection and comprehension of hidden calling subjects at distances between 322 and 2510 m when compared with unaided hearing. This study supports the use of a parabolic microphone in search and rescue to locate responsive subjects in favorable weather and terrain. Copyright © 2017 The Authors. Published by Elsevier Inc. All rights reserved.

Floor cooler for floor trough of a nuclear reactor

International Nuclear Information System (INIS)

Friedrich, H.J.

1985-01-01

Cooling pipes are situated below the floor trough of a BWR, which are connected to the annular distribution or collection pipes. The distribution and collection pipes are connected by parallel hairpin pipes with involute shape to the centre of the floor trough. These hairpin pipes are situated in a lower plane than the annular distribution pipe to the centre and in a higher plane from the centre to the outer annular collector pipe. (orig./HP) [de

Reflector homogenization

Energy Technology Data Exchange (ETDEWEB)

Sanchez, R.; Ragusa, J.; Santandrea, S. [Commissariat a l' Energie Atomique, Direction de l' Energie Nucleaire, Service d' Etudes de Reacteurs et de Modelisation Avancee, CEA de Saclay, DM2S/SERMA 91 191 Gif-sur-Yvette cedex (France)]. e-mail: richard.sanchez@cea.fr

2004-07-01

The problem of the determination of a homogeneous reflector that preserves a set of prescribed albedo is considered. Duality is used for a direct estimation of the derivatives needed in the iterative calculation of the optimal homogeneous cross sections. The calculation is based on the preservation of collapsed multigroup albedo obtained from detailed reference calculations and depends on the low-order operator used for core calculations. In this work we analyze diffusion and transport as low-order operators and argue that the P{sub 0} transfers are the best choice for the unknown cross sections to be adjusted. Numerical results illustrate the new approach for SP{sub N} core calculations. (Author)

Reflector homogenization

International Nuclear Information System (INIS)

Sanchez, R.; Ragusa, J.; Santandrea, S.

2004-01-01

The problem of the determination of a homogeneous reflector that preserves a set of prescribed albedo is considered. Duality is used for a direct estimation of the derivatives needed in the iterative calculation of the optimal homogeneous cross sections. The calculation is based on the preservation of collapsed multigroup albedo obtained from detailed reference calculations and depends on the low-order operator used for core calculations. In this work we analyze diffusion and transport as low-order operators and argue that the P 0 transfers are the best choice for the unknown cross sections to be adjusted. Numerical results illustrate the new approach for SP N core calculations. (Author)

Identifying the principal coefficient of parabolic equations with non-divergent form

International Nuclear Information System (INIS)

Jiang, L S; Bian, B J

2005-01-01

We deal with an inverse problem of determining a coefficient a(x, t) of principal part for second order parabolic equations with non-divergent form when the solution is known. Such a problem has important applications in a large fields of applied science. We propose a well-posed approximate algorithm to identify the coefficient. The existence, uniqueness and stability of such solutions a(x, t) are proved. A necessary condition which is a couple system of a parabolic equation and a parabolic variational inequality is deduced. Our numerical simulations show that the coefficient is recovered very well

Identifying the principal coefficient of parabolic equations with non-divergent form

Science.gov (United States)

Jiang, L. S.; Bian, B. J.

2005-01-01

We deal with an inverse problem of determining a coefficient a(x, t) of principal part for second order parabolic equations with non-divergent form when the solution is known. Such a problem has important applications in a large fields of applied science. We propose a well-posed approximate algorithm to identify the coefficient. The existence, uniqueness and stability of such solutions a(x, t) are proved. A necessary condition which is a couple system of a parabolic equation and a parabolic variational inequality is deduced. Our numerical simulations show that the coefficient is recovered very well.

Sasakian and Parabolic Higgs Bundles

Science.gov (United States)

Biswas, Indranil; Mj, Mahan

2018-03-01

Let M be a quasi-regular compact connected Sasakian manifold, and let N = M/ S 1 be the base projective variety. We establish an equivalence between the class of Sasakian G-Higgs bundles over M and the class of parabolic (or equivalently, ramified) G-Higgs bundles over the base N.

Theoretical modeling of the dynamics of a semiconductor laser subject to double-reflector optical feedback

Energy Technology Data Exchange (ETDEWEB)

Bakry, A. [King Abdulaziz University, 80203, Department of Physics, Faculty of Science (Saudi Arabia); Abdulrhmann, S. [Jazan University, 114, Department of Physics, Faculty of Sciences (Saudi Arabia); Ahmed, M., E-mail: mostafa.farghal@mu.edu.eg [King Abdulaziz University, 80203, Department of Physics, Faculty of Science (Saudi Arabia)

2016-06-15

We theoretically model the dynamics of semiconductor lasers subject to the double-reflector feedback. The proposed model is a new modification of the time-delay rate equations of semiconductor lasers under the optical feedback to account for this type of the double-reflector feedback. We examine the influence of adding the second reflector to dynamical states induced by the single-reflector feedback: periodic oscillations, period doubling, and chaos. Regimes of both short and long external cavities are considered. The present analyses are done using the bifurcation diagram, temporal trajectory, phase portrait, and fast Fourier transform of the laser intensity. We show that adding the second reflector attracts the periodic and perioddoubling oscillations, and chaos induced by the first reflector to a route-to-continuous-wave operation. During this operation, the periodic-oscillation frequency increases with strengthening the optical feedback. We show that the chaos induced by the double-reflector feedback is more irregular than that induced by the single-reflector feedback. The power spectrum of this chaos state does not reflect information on the geometry of the optical system, which then has potential for use in chaotic (secure) optical data encryption.

Phase-Change Thermal Energy Storage

Science.gov (United States)

1989-11-01

The goal of this program is to advance the engineering and scientific understanding of solar thermal technology and to establish the technology base from which private industry can develop solar thermal power production options for introduction into the competitive energy market. Solar thermal technology concentrates the solar flux using tracking mirrors or lenses onto a receiver where the solar energy is absorbed as heat and converted into electricity or incorporated into products as process heat. The two primary solar thermal technologies, central receivers and distributed receivers, employ various point and line-focus optics to concentrate sunlight. Current central receiver systems use fields of heliostats (two-axes tracking mirrors) to focus the sun's radiant energy onto a single, tower-mounted receiver. Point focus concentrators up to 17 meters in diameter track the sun in two axes and use parabolic dish mirrors or Fresnel lenses to focus radiant energy onto a receiver. Troughs and bowls are line-focus tracking reflectors that concentrate sunlight onto receiver tubes along their focal lines. Concentrating collector modules can be used alone or in a multimodule system. The concentrated radiant energy absorbed by the solar thermal receiver is transported to the conversion process by a circulating working fluid. Receiver temperatures range from 100 C in low-temperature troughs to over 1500 C in dish and central receiver systems.

Temperature Knowledge and Model Correlation for the Soil Moisture Active and Passive (SMAP) Reflector Mesh

Science.gov (United States)

Mikhaylov, Rebecca; Dawson, Douglas; Kwack, Eug

2014-01-01

NASA's Earth observing Soil Moisture Active & Passive (SMAP) Mission is scheduled to launch in November 2014 into a 685 km near-polar, sun synchronous orbit. SMAP will provide comprehensive global mapping measurements of soil moisture and freeze/thaw state in order to enhance understanding of the processes that link the water, energy, and carbon cycles. The primary objectives of SMAP are to improve worldwide weather and flood forecasting, enhance climate prediction, and refine drought and agriculture monitoring during its 3 year mission. The SMAP instrument architecture incorporates an L-band radar and an L-band radiometer which share a common feed horn and parabolic mesh reflector. The instrument rotates about the nadir axis at approximately 15 rpm, thereby providing a conically scanning wide swath antenna beam that is capable of achieving global coverage within 3 days. In order to make the necessary precise surface emission measurements from space, a temperature knowledge of 60 deg C for the mesh reflector is required. In order to show compliance, a thermal vacuum test was conducted using a portable solar simulator to illuminate a non flight, but flight-like test article through the quartz window of the vacuum chamber. The molybdenum wire of the antenna mesh is too fine to accommodate thermal sensors for direct temperature measurements. Instead, the mesh temperature was inferred from resistance measurements made during the test. The test article was rotated to five separate angles between 10 deg and 90 deg via chamber breaks to simulate the maximum expected on-orbit solar loading during the mission. The resistance measurements were converted to temperature via a resistance versus temperature calibration plot that was constructed from data collected in a separate calibration test. A simple thermal model of two different representations of the mesh (plate and torus) was created to correlate the mesh temperature predictions to within 60 deg C. The on-orbit mesh

Feasibility for the Use of Flat Booster Reflectors in Various Photovoltaic Installations

OpenAIRE

Gelegenis, John Joachim; Axaopoulos, Petros; Misailidis, Stavros; Giannakidis, George; Samarakou, Maria; Bonaros, Bassilios

2016-01-01

The feasibility for the addition of flat booster reflectors to PV panels is techno-economically investigated for various applications (building attached PVs, ground installations, grid-connected or stand-alone units) and various PV types (mono-crystalline and amorphous silicon PV panels). A model developed to this aim is applied to optimize the parameters of the PV/reflector module and to evaluate its applicability according to the solar radiation data of Athens (Greece). The reflectors may l...

Crustal and upper mantle velocity structure of the Salton Trough, southeast California

Science.gov (United States)

Parsons, T.; McCarthy, J.

1996-01-01

This paper presents data and modelling results from a crustal and upper mantle wide-angle seismic transect across the Salton Trough region in southeast California. The Salton Trough is a unique part of the Basin and Range province where mid-ocean ridge/transform spreading in the Gulf of California has evolved northward into the continent. In 1992, the U.S. Geological Survey (USGS) conducted the final leg of the Pacific to Arizona Crustal Experiment (PACE). Two perpendicular models of the crust and upper mantle were fit to wide-angle reflection and refraction travel times, seismic amplitudes, and Bouguer gravity anomalies. The first profile crossed the Salton Trough from the southwest to the northeast, and the second was a strike line that paralleled the Salton Sea along its western edge. We found thin crust (???21-22 km thick) beneath the axis of the Salton Trough (Imperial Valley) and locally thicker crust (???27 km) beneath the Chocolate Mountains to the northeast. We modelled a slight thinning of the crust further to the northeast beneath the Colorado River (???24 km) and subsequent thickening beneath the metamorphic core complex belt northeast of the Colorado River. There is a deep, apparently young basin (???5-6 km unmetamorphosed sediments) beneath the Imperial Valley and a shallower (???2-3 km) basin beneath the Colorado River. A regional 6.9-km/s layer (between ???15-km depth and the Moho) underlies the Salton Trough as well as the Chocolate Mountains where it pinches out at the Moho. This lower crustal layer is spatially associated with a low-velocity (7.6-7.7 km/s) upper mantle. We found that our crustal model is locally compatible with the previously suggested notion that the crust of the Salton Trough has formed almost entirely from magmatism in the lower crust and sedimentation in the upper crust. However, we observe an apparently magmatically emplaced lower crust to the northeast, outside of the Salton Trough, and propose that this layer in part

A Two-Species Cooperative Lotka-Volterra System of Degenerate Parabolic Equations

Directory of Open Access Journals (Sweden)

Jiebao Sun

2011-01-01

parabolic equations. We are interested in the coexistence of the species in a bounded domain. We establish the existence of global generalized solutions of the initial boundary value problem by means of parabolic regularization and also consider the existence of the nontrivial time-periodic solution for this system.

Nanofocusing Parabolic Refractive X-Ray Lenses

International Nuclear Information System (INIS)

Schroer, C.G.; Kuhlmann, M.; Hunger, U.T.; Guenzler, T.F.; Kurapova, O.; Feste, S.; Lengeler, B.; Drakopoulos, M.; Somogyi, A.; Simionovici, A. S.; Snigirev, A.; Snigireva, I.

2004-01-01

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

Highly Enriched Uranium Metal Cylinders Surrounded by Various Reflector Materials

International Nuclear Information System (INIS)

Bernard Jones; J. Blair Briggs; Leland Monteirth

2007-01-01

A series of experiments was performed at Los Alamos Scientific Laboratory in 1958 to determine critical masses of cylinders of Oralloy (Oy) reflected by a number of materials. The experiments were all performed on the Comet Universal Critical Assembly Machine, and consisted of discs of highly enriched uranium (93.3 wt.% 235U) reflected by half-inch and one-inch-thick cylindrical shells of various reflector materials. The experiments were performed by members of Group N-2, particularly K. W. Gallup, G. E. Hansen, H. C. Paxton, and R. H. White. This experiment was intended to ascertain critical masses for criticality safety purposes, as well as to compare neutron transport cross sections to those obtained from danger coefficient measurements with the Topsy Oralloy-Tuballoy reflected and Godiva unreflected critical assemblies. The reflector materials examined in this series of experiments are as follows: magnesium, titanium, aluminum, graphite, mild steel, nickel, copper, cobalt, molybdenum, natural uranium, tungsten, beryllium, aluminum oxide, molybdenum carbide, and polythene (polyethylene). Also included are two special configurations of composite beryllium and iron reflectors. Analyses were performed in which uncertainty associated with six different parameters was evaluated; namely, extrapolation to the uranium critical mass, uranium density, 235U enrichment, reflector density, reflector thickness, and reflector impurities. In addition to the idealizations made by the experimenters (removal of the platen and diaphragm), two simplifications were also made to the benchmark models that resulted in a small bias and additional uncertainty. First of all, since impurities in core and reflector materials are only estimated, they are not included in the benchmark models. Secondly, the room, support structure, and other possible surrounding equipment were not included in the model. Bias values that result from these two simplifications were determined and associated

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

Science.gov (United States)

Carl, Siegfried; Le, Vy K.

2014-10-01

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

Chronostratigraphy and deposition rates in the Okinawa Trough region

Institute of Scientific and Technical Information of China (English)

李培英; 王永吉; 刘振夏

1999-01-01

Six representative cores from Okinawa Trough have been dated using AMS 14C, Standard 14C and ESR methods, and comparatively analysed. Systematic measurements of the oriented samples taken from the cores were conducted for obtaining their remnant magnetic polarity. With the aid of the dates obtained, particularly the AMS 14C ages of planktonic foraminiferal tests, two polarity events and two polar wanderings of the earth magnetic field have been defined. Calculations of the deposition rates for all the six core sites indicate rather high values in the trough plain, at least equivalent to those rates reported for the region of the East China Sea. They commonly range from 10 to 30 cm/ka, and even greater than 40 cm/ka in some localities. The deposition rate varied widely with topography and periods of time. In general, it is greater during the postglacial period than during the last glaciation. The chronostratigraphy in the Okinawa Trough region established through this study argues against the pr

Wavelength-controlled external-cavity laser with a silicon photonic crystal resonant reflector

Science.gov (United States)

Gonzalez-Fernandez, A. A.; Liles, Alexandros A.; Persheyev, Saydulla; Debnath, Kapil; O'Faolain, Liam

2016-03-01

We report the experimental demonstration of an alternative design of external-cavity hybrid lasers consisting of a III-V Semiconductor Optical Amplifier with fiber reflector and a Photonic Crystal (PhC) based resonant reflector on SOI. The Silicon reflector comprises a polymer (SU8) bus waveguide vertically coupled to a PhC cavity and provides a wavelength-selective optical feedback to the laser cavity. This device exhibits milliwatt-level output power and sidemode suppression ratio of more than 25 dB.

Explicit nonlinear finite element geometric analysis of parabolic leaf springs under various loads.

Science.gov (United States)

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

2013-01-01

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

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

Directory of Open Access Journals (Sweden)

Y. S. Kong

2013-01-01

Full Text Available 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.

Enhancement of thermal neutron self-shielding in materials surrounded by reflectors

International Nuclear Information System (INIS)

Cornelia Chilian; Gregory Kennedy

2012-01-01

Materials containing from 41 to 1124 mg chlorine and surrounded by polyethylene containers of various thicknesses, from 0.01 to 5.6 mm, were irradiated in a research reactor neutron spectrum and the 38 Cl activity produced was measured as a function of polyethylene reflector thickness. For the material containing the higher amount of chlorine, the 38 Cl specific activity decreased with increasing reflector thickness, indicating increased neutron self-shielding. It was found that the amount of neutron self-shielding increased by as much as 52% with increasing reflector thickness. This is explained by neutrons which have exited the material subsequently reflecting back into it and thus increasing the total mean path length in the material. All physical and empirical models currently used to predict neutron self-shielding have ignored this effect and need to be modified. A method is given for measuring the adjustable parameter of a self-shielding model for a particular sample size and combination of neutron reflectors. (author)

An introduction to geometric theory of fully nonlinear parabolic equations

International Nuclear Information System (INIS)

Lunardi, A.

1991-01-01

We study a class of nonlinear evolution equations in general Banach space being an abstract version of fully nonlinear parabolic equations. In addition to results of existence, uniqueness and continuous dependence on the data, we give some qualitative results about stability of the stationary solutions, existence and stability of the periodic orbits. We apply such results to some parabolic problems arising from combustion theory. (author). 24 refs

Canonical generators of the cohomology of moduli of parabolic bundles on curves

International Nuclear Information System (INIS)

Biswas, I.; Raghavendra, N.

1994-11-01

We determine generators of the rational cohomology algebras of moduli spaces of parabolic vector bundles on a curve, under some 'primality' conditions on the parabolic datum. These generators are canonical in a precise sense. Our results are new even for usual vector bundles (i.e., vector bundles without parabolic structure) whose rank is greater than 2 and is coprime to the degree; in this case, they are generalizations of a theorem of Newstead on the moduli of vector bundles of rank 2 and odd degree. (author). 11 refs

Study of light collection uniformity dependence on reflector type in a large scintillation counter

International Nuclear Information System (INIS)

Astvatsaturov, R.G.; Ivanov, V.I.; Knapik, E.; Kramarenko, V.A.; Malakhov, A.I.; Khachaturyan, M.N.

1977-01-01

An investigation of the way to improve uniformity of light collection onto photoelectric multiplier photocathode, for the 100x10x2 cm scintillation counter, has been undertaken. Pulse amplitude versus the point, particles strike a scintillator, relationship, has been demonstrated for several types of reflectors. Used as reflectors were: white papar, aluminium foil, black papar and a combination of above reflectors. Experimental data analysis shows, that the combination of reflectors with different reflection coefficient, provides a means for 1,5 time improvement of counter light collection uniformity, with no impairment of amplitude characteristics

Performance of Cat's Eye Modulating Retro-Reflectors for Free-Space Optical Communications

National Research Council Canada - National Science Library

Rabinovich, W. S; Goetz, P. G; Mahon, R; Swingen, L; Murphy, J; Gilbreath, G. C; Binari, S; Waluschka, E

2004-01-01

Modulating retro-reflectors (MRR) couple passive optical retro-reflectors with electro-optic modulators to allow free-space optical communication with a laser and pointing/acquisition/tracking system required on only one end of the link...

On the behaviour of solutions of parabolic equations for large values of time

International Nuclear Information System (INIS)

Denisov, V N

2005-01-01

This paper is a survey of classical and new results on stabilization of solutions of the Cauchy problem and mixed problems for second-order linear parabolic equations. Proofs are given for some new results about exact sufficient conditions on the behaviour of lower-order coefficients of the parabolic equation; these conditions ensure stabilization of a solution of the Cauchy problem for the parabolic equation in the class of bounded or increasing initial functions

Bottom reflector for power reactors

International Nuclear Information System (INIS)

Elter, C.; Kissel, K.F.; Schoening, J.; Schwiers, H.G.

1982-01-01

In pebble bed reactors erosion and damage due fuel elements movement on the surface of the bottom reflector should be minimized. This can be achieved by chamfering and/or rounding the cover edges of the graphite blocks and the edges between the drilled holes and the surface of the graphite block. (orig.) [de

Transport equivalent diffusion constants for reflector region in PWRs

International Nuclear Information System (INIS)

Tahara, Yoshihisa; Sekimoto, Hiroshi

2002-01-01

The diffusion-theory-based nodal method is widely used in PWR core designs for reason of its high computing speed in three-dimensional calculations. The baffle/reflector (B/R) constants used in nodal calculations are usually calculated based on a one-dimensional transport calculation. However, to achieve high accuracy of assembly power prediction, two-dimensional model is needed. For this reason, the method for calculating transport equivalent diffusion constants of reflector material was developed so that the neutron currents on the material boundaries could be calculated exactly in diffusion calculations. Two-dimensional B/R constants were calculated using the transport equivalent diffusion constants in the two-dimensional diffusion calculation whose geometry reflected the actual material configuration in the reflector region. The two-dimensional B/R constants enabled us to predict assembly power within an error of 1.5% at hot full power conditions. (author)

Full-energy-chain analysis of greenhouse gas emissions for solar thermal electric power generation systems

International Nuclear Information System (INIS)

Norton, B.; Lawson, W.R.

1997-01-01

Technical attributes and environmental impacts of solar thermal options for centralized electricity generation are discussed. In particular, the full-energy-chain, including embodied energy and energy production, is considered in relation to greenhouse gas emission arising from solar thermal electricity generation. Central receiver, parabolic dish, parabolic trough and solar pond systems are considered. (author)

Analysis and test of a 16-foot radial rib reflector developmental model

Science.gov (United States)

Birchenough, Shawn A.

1989-01-01

Analytical and experimental modal tests were performed to determine the vibrational characteristics of a 16-foot diameter radial rib reflector model. Single rib analyses and experimental tests provided preliminary information relating to the reflector. A finite element model predicted mode shapes and frequencies of the reflector. The analyses correlated well with the experimental tests, verifying the modeling method used. The results indicate that five related, characteristic mode shapes form a group. The frequencies of the modes are determined by the relative phase of the radial ribs.

Artificial neural networks approach on solar parabolic dish cooker

International Nuclear Information System (INIS)

Lokeswaran, S.; Eswaramoorthy, M.

2011-01-01

This paper presents heat transfer analysis of solar parabolic dish cooker using Artificial Neural Network (ANN). The objective of this study to envisage thermal performance parameters such as receiver plate and pot water temperatures of the solar parabolic dish cooker by using the ANN for experimental data. An experiment is conducted under two cases (1) cooker with plain receiver and (2) cooker with porous receiver. The Back Propagation (BP) algorithm is used to train and test networks and ANN predictions are compared with experimental results. Different network configurations are studied by the aid of searching a relatively better network for prediction. The results showed a good regression analysis with the correlation coefficients in the range of 0.9968-0.9992 and mean relative errors (MREs) in the range of 1.2586-4.0346% for the test data set. Thus ANN model can successfully be used for the prediction of the thermal performance parameters of parabolic dish cooker with reasonable degree of accuracy. (authors)

Tear trough – Anatomy and treatment by autologous fat grafting

Directory of Open Access Journals (Sweden)

Chang Yung Chia

2016-07-01

Full Text Available Tear trough is the main irregularity at midface, of which treatment is difficult. There is no agreement in literature about its anatomy and best treatment. The author presented an anatomical study and personal autologous fat grafting technique for tear trough treatment. Anatomical dissections were done on two fresh cadavers to examine the skin, subcutaneous, muscle and bone layers, spaces, and attachments. Safety and efficacy were evaluated via retrospective analysis of the last 200 consecutive procedures performed by the author. Tear trough is caused by the abrupt transition of the palpebral orbicular oculi muscle (OOM (i.e., thin skin without subcutaneous fat compartment to the orbital OOM (i.e., thicker skin with malar fat compartment. The tear trough region is located at the OOM bony origin at the medial canthus where no specific ligament was found. The grafted fat volume stabilized at two or three months after the procedure, instead of six months as stated in literature, with excellent results and no severe complications. Tear trough is a personal characteristic, a natural anatomical depression caused by subcutaneous irregularity and can worsen with age. The lack of volume is not effectively corrected by surgeries and thus it must be filled. Fat grafting has several advantages over alloplastic fillers, although it may be more difficult. Fat graft is autologous and abundant, and tissue transplantation could enhance skin quality. Fat grafting is a simple, safe, and effective solution for adding extra volume to correct the deflation phenomenon of the midface aging process. There is no specific anatomical plane for volume injection; the fat graft must be evenly distributed in the deep and superficial plane for uniformity.

Parabolic dish collectors - A solar option

Science.gov (United States)

Truscello, V. C.

1981-05-01

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

Spheroidal corrections to the spherical and parabolic bases of the hydrogen atom

International Nuclear Information System (INIS)

Mardyan, L.G.; Pogosyan, G.S.; Sisakyan, A.N.

1986-01-01

This paper introduces the bases of the hydrogen atom and obtains recursion relations that determine the expansion of the spheroidal basis with respect to its parabolic basis. The leading spheroidal corrections to the spherical and parabolic bases are calculated by perturbation theory

Some integral representations and limits for (products of) the parabolic cylinder function

NARCIS (Netherlands)

Veestraeten, D.

2016-01-01

Recently, [Veestraeten D. On the inverse transform of Laplace transforms that contain (products of) the parabolic cylinder function. Integr Transf Spec F 2015;26:859-871] derived inverse Laplace transforms for Laplace transforms that contain products of two parabolic cylinder functions by exploiting

Effectiveness of solar disinfection using batch reactors with non-imaging aluminium reflectors under real conditions: Natural well-water and solar light.

Science.gov (United States)

Navntoft, C; Ubomba-Jaswa, E; McGuigan, K G; Fernández-Ibáñez, P

2008-12-11

Inactivation kinetics are reported for suspensions of Escherichia coli in well-water using compound parabolic collector (CPC) mirrors to enhance the efficiency of solar disinfection (SODIS) for batch reactors under real, solar radiation (cloudy and cloudless) conditions. On clear days, the system with CPC reflectors achieved complete inactivation (more than 5-log unit reduction in bacterial population to below the detection limit of 4CFU/mL) one hour sooner than the system fitted with no CPC. On cloudy days, only systems fitted with CPCs achieved complete inactivation. Degradation of the mirrors under field conditions was also evaluated. The reflectivity of CPC systems that had been in use outdoors for at least 3 years deteriorated in a non-homogeneous fashion. Reflectivity values for these older systems were found to vary between 27% and 72% compared to uniform values of 87% for new CPC systems. The use of CPC has been proven to be a good technological enhancement to inactivate bacteria under real conditions in clear and cloudy days. A comparison between enhancing optics and thermal effect is also discussed.

Maximum principles for boundary-degenerate linear parabolic differential operators

OpenAIRE

Feehan, Paul M. N.

2013-01-01

We develop weak and strong maximum principles for boundary-degenerate, linear, parabolic, second-order partial differential operators, $Lu := -u_t-\\tr(aD^2u)-\\langle b, Du\\rangle + cu$, with \\emph{partial} Dirichlet boundary conditions. The coefficient, $a(t,x)$, is assumed to vanish along a non-empty open subset, $\\mydirac_0!\\sQ$, called the \\emph{degenerate boundary portion}, of the parabolic boundary, $\\mydirac!\\sQ$, of the domain $\\sQ\\subset\\RR^{d+1}$, while $a(t,x)$ may be non-zero at po...

Morphological evolution of Jinshan Trough in Hangzhou Bay (China) from 1960 to 2011

Science.gov (United States)

Liu, Yifei; Xia, Xiaoming; Chen, Shenliang; Jia, Jianjun; Cai, Tinglu

2017-11-01

An extensive system of tidal channels, starting with Jinshan Trough in the east, is located along the north shore of Hangzhou Bay, China. This contribution investigates the morphological evolution of Jinshan Trough by using 17 bathymetric charts from a series covering a period of 51 years from 1960 to 2011. Three stages of evolution during this period are distinguishable based on the morphology and annual mean volume data. The first stage (1960-1987) is characterized by extension of the trough; the second stage (1987-1996) is a relatively stable period with some adjustments in the trough morphology; the third stage (1996-2011) is marked by the processes of erosion and deposition in the beginning of the period and a subsequent slow erosion process. Spatio-temporal variability of the trough was evaluated by using empirical orthogonal function (EOF) analysis. The first eigenfunction indicates that erosion is the main evolution process and there exists three stages similar to those distinguished from volume variations. The second eigenfunction mainly reflects erosion and deposition in the northwest part of the trough located in the flood tidal current shadow area of the artificial headland in Jinshan. The third eigenfunction mainly reflects annual fluctuations of erosion and deposition in the side slope at the artificial headland in Jinshan. A particularly intense erosion process occurred between 1996 and 1998. The major effects on morphological evolution in Jinshan Trough from 1960 to 2011 were investigated and tentative conclusions were presented. Continuous coastal reclamations in Jinshan had the most pronounced effect on the morphological evolution during the first and the second stages. The storm surge had a pronounced effect on the evolution at the beginning of the third stage.

Irreversible thermodynamics, parabolic law and self-similar state in grain growth

International Nuclear Information System (INIS)

Rios, P.R.

2004-01-01

The formalism of the thermodynamic theory of irreversible processes is applied to grain growth to investigate the nature of the self-similar state and its corresponding parabolic law. Grain growth does not reach a steady state in the sense that the entropy production remains constant. However, the entropy production can be written as a product of two factors: a scale factor that tends to zero for long times and a scaled entropy production. It is suggested that the parabolic law and the self-similar state may be associated with the minimum of this scaled entropy production. This result implies that the parabolic law and the self-similar state have a sound irreversible thermodynamical basis

A Two-Species Cooperative Lotka-Volterra System of Degenerate Parabolic Equations

OpenAIRE

Sun, Jiebao; Zhang, Dazhi; Wu, Boying

2011-01-01

We consider a cooperating two-species Lotka-Volterra model of degenerate parabolic equations. We are interested in the coexistence of the species in a bounded domain. We establish the existence of global generalized solutions of the initial boundary value problem by means of parabolic regularization and also consider the existence of the nontrivial time-periodic solution for this system.

Small-scale installations. Solar concentration system for architectural integration; Instalaciones de pequeno tamano. Sistema de concetracion solar para integracion arquitectonica

Energy Technology Data Exchange (ETDEWEB)

Chemisana, D.; Rosell, J.

2010-07-01

Concentration solar systems now practically limit its use in large installations with devices of considerable size, such as generator systems central tower parabolic trough concentrators for power generation. Disco-parabolic concentrators with Stirling engine or the great fans that support two-axis Fresnel lenses in combination with occasional multilayered cells with or without secondary concentrator. (Author) 11 refs.

Albedo-adjusted fast-neutron diffusion coefficients in reactor reflectors

International Nuclear Information System (INIS)

Terney, W.B.

1975-01-01

In the newer, larger pressurized-water reactor cores, the calculated power distributions are fairly sensitive to the number of neutron groups used and to the treatment of the reflector cross sections. Comparisons between transport and diffusion calculations show that the latter substantially underpredict the reflector albedos in the fast (top) group and that the power distribution is shifted toward the core center when compared to 4-group transport theory results. When the fast-neutron diffusion coefficients are altered to make the transport- and diffusion-theory albedos agree, the power distributions are also brought into agreement. An expression for the fast-neutron diffusion coefficients in reflector regions has been derived such that the diffusion calculation reproduces the albedo obtained from a transport solution. In addition, a correction factor for mesh effects applicable to coarse mesh problems is presented. The use of the formalism gives the correct albedos and improved power distributions. (U.S.)

The dynamics of parabolic flight: Flight characteristics and passenger percepts

Science.gov (United States)

Karmali, Faisal; Shelhamer, Mark

2008-09-01

Flying a parabolic trajectory in an aircraft is one of the few ways to create freefall on Earth, which is important for astronaut training and scientific research. Here we review the physics underlying parabolic flight, explain the resulting flight dynamics, and describe several counterintuitive findings, which we corroborate using experimental data. Typically, the aircraft flies parabolic arcs that produce approximately 25 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.

Optical properties of V-trough concentrators

Energy Technology Data Exchange (ETDEWEB)

Fraidenraich, N. [Universidade Federal de Pernambuco, Recife, PE Brasil (Brazil); Almeida, G. J.

1991-07-01

A new approach to study the optical behavior of V-trough concentrators is developed, based on the use of three characteristic angles defining the appearance, disappearance and return to the outside space of the cavity of a reflection mode. The probability of occurrence of a given number of reflections for beam radiation is determined as a function of these angles and the optical efficiency calculated. It is shown that the optical efficiency can be approximated by a function of two parameters, the angular acceptance function, T, and the mean number of reflections, n, as T * p{sup n/T}. Deviations between exact and approximate optical efficiency increase as n increases or as p decreases. For troughs with C ≤ 2.5 the maximal error for beam radiation is 3.4% for p ≥ 0.8 (8.3% for p ≥ 0.7). For diffuse radiation the maximal error is less than 2% for configurations whose optical efficiency is above 0.6. A further simplification was introduced to obtain the optical efficiency for diffuse radiation, approximating T by an analytical expression and n by an empirical linear function of the inverse of the vertex angle. Results accurate up to 5% for p = 0.8, were obtained. Increasing the concentration ratio, C, from 1.5 to 2.5 for a vertex angle being one third of the acceptance angle, decreased the optical efficiency from 0.74 to 0.59, for p = 0.8. For a given C, the dependence of the optical efficiency on the vertex angle is rather weak, suggesting that large trough angles might be favoured by cost-benefit analysis. (author)

Performance improvement of the finned passive PVT system using reflectors like removable insulation covers

International Nuclear Information System (INIS)

Ziapour, Behrooz M.; Palideh, Vahid; Mokhtari, Farhad

2016-01-01

Highlights: • A passive PVT system means the combination of a PV panel and a compact solar water heater. • Comparative study was done on performance characteristics in passive and hybrid PVT systems. • Reflectors effects on performance of a finned passive PVT system were numerically studied. • Results show that the finned passive PVT system has higher performance than the hybrid type. • Reflectors reduce the night heat losses and increase the solar radiation rate on PVT system. - Abstract: A passive photovoltaic–thermal system (PVT) is the combination of a photovoltaic (PV) panel and a compact solar water heater for co-generation of heat and electricity. This system bears considerable heat losses to ambient, particularly at noncollection times. One simple way to overcome this problem is to use a removable insulation cover on the collector's outer glazing. In this paper, the effects of the reflectors on day and night performance of a finned passive PVT system were numerically studied. At nonenergy collection time, the reflectors can turn and cover the collector cover glass as a nonconductor material. Simulation results showed that the reflectors reduce the night heat losses and increase the solar radiation rate on the absorber plate. The use of removable insulation reflectors resulted to saving extra sensibly thermal energy. Also, the solar cells power generation (P_s_c), in the case of reflectors installed, was reinforced.

Analysis of Earthquake Source Spectra in Salton Trough

Science.gov (United States)

Chen, X.; Shearer, P. M.

2009-12-01

Previous studies of the source spectra of small earthquakes in southern California show that average Brune-type stress drops vary among different regions, with particularly low stress drops observed in the Salton Trough (Shearer et al., 2006). The Salton Trough marks the southern end of the San Andreas Fault and is prone to earthquake swarms, some of which are driven by aseismic creep events (Lohman and McGuire, 2007). In order to learn the stress state and understand the physical mechanisms of swarms and slow slip events, we analyze the source spectra of earthquakes in this region. We obtain Southern California Seismic Network (SCSN) waveforms for earthquakes from 1977 to 2009 archived at the Southern California Earthquake Center (SCEC) data center, which includes over 17,000 events. After resampling the data to a uniform 100 Hz sample rate, we compute spectra for both signal and noise windows for each seismogram, and select traces with a P-wave signal-to-noise ratio greater than 5 between 5 Hz and 15 Hz. Using selected displacement spectra, we isolate the source spectra from station terms and path effects using an empirical Green’s function approach. From the corrected source spectra, we compute corner frequencies and estimate moments and stress drops. Finally we analyze spatial and temporal variations in stress drop in the Salton Trough and compare them with studies of swarms and creep events to assess the evolution of faulting and stress in the region. References: Lohman, R. B., and J. J. McGuire (2007), Earthquake swarms driven by aseismic creep in the Salton Trough, California, J. Geophys. Res., 112, B04405, doi:10.1029/2006JB004596 Shearer, P. M., G. A. Prieto, and E. Hauksson (2006), Comprehensive analysis of earthquake source spectra in southern California, J. Geophys. Res., 111, B06303, doi:10.1029/2005JB003979.

Photogrammetry Of A Parabolic Antenna

Science.gov (United States)

Merrick, W. D.; Lansing, F. L.; Stoller, F. W.; Lobb, V. B.

1988-01-01

Surface measured with accuracy better than 10 to the negative fifth power times diameter. Report describes use of advanced close-range photogrammetry to determine deviations of 34-m-diameter antenna main reflector and subreflector from nominal paraboloidal shapes. Measurements enable removal of linear offsets and angular misalignments of subreflector, with consequent increase of 4 percent in aperture efficiency.

The reflector effect on the neutron lifetimes in the IPEN/MB-01 reactor

International Nuclear Information System (INIS)

Gonnelli, Eduardo

2013-01-01

The aim of this study is to present the reflector effect on the neutron lifetimes in the IPEN/MB-01 reactor. The proposed method requires an approach which takes into account both the reflector and the core, so that the point kinetics equations, which constitute the theoretical basis of all mathematical development, contemplate both regions of the reactor. From these equations, as known as two regions kinetics point equations, theoretical expressions are obtained for the Auto Power Spectral Densities (APSD), which are used for least squares fit of the experimental data of APSD obtained in several subcritical states. The prompt neutron generation time, the neutron lifetimes in the reflector and the neutron return fraction from the reflector to the core are derived from the fitting. (author)

Improvement of Axial Reflector Cross Section Generation Model for PWR Core Analysis

Energy Technology Data Exchange (ETDEWEB)

Shim, Cheon Bo; Lee, Kyung Hoon; Cho, Jin Young [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

2016-10-15

This paper covers the study for improvement of axial reflector XS generation model. In the next section, the improved 1D core model is represented in detail. Reflector XS generated by the improved model is compared to that of the conventional model in the third section. Nuclear design parameters generated by these two XS sets are also covered in that section. Significant of this study is discussed in the last section. Two-step procedure has been regarded as the most practical approach for reactor core designs because it offers core design parameters quite rapidly within acceptable range. Thus this approach is adopted for SMART (System-integrated Modular Advanced Reac- Tor) core design in KAERI with the DeCART2D1.1/ MASTER4.0 (hereafter noted as DeCART2D/ MASTER) code system. Within the framework of the two-step procedure based SMART core design, various researches have been studied to improve the core design reliability and efficiency. One of them is improvement of reflector cross section (XS) generation models. While the conventional FA/reflector two-node model used for most core designs to generate reflector XS cannot consider the actual configuration of fuel rods that intersect at right angles to axial reflectors, the revised model reflects the axial fuel configuration by introducing the radially simplified core model. The significance of the model revision is evaluated by observing HGC generated by DeCART2D, reflector XS, and core design parameters generated by adopting the two models. And it is verified that about 30 ppm CBC error can be reduced and maximum Fq error decreases from about 6 % to 2.5 % by applying the revised model. Error of AO and axial power shapes are also reduced significantly. Therefore it can be concluded that the simplified 1D core model improves the accuracy of the axial reflector XS and leads to the two-step procedure reliability enhancement. Since it is hard for core designs to be free from the two-step approach, it is necessary to find

A note on Hermitian-Einstein metrics on parabolic stable bundles

International Nuclear Information System (INIS)

Li Jiayu; Narasimhan, M.S.

2000-01-01

Let M-bar be a compact complex manifold of complex dimension two with a smooth Kaehler metric and D a smooth divisor on M-bar. If E is a rank 2 holomorphic vector bundle on M-bar with a stable parabolic structure along D, we prove that there exists a Hermitian-Einstein metric on E' = E-vertical bar M-barbackslashD compatible with the parabolic structure, and whose curvature is square integrable. (author)

Critical spaces for quasilinear parabolic evolution equations and applications

Science.gov (United States)

Prüss, Jan; Simonett, Gieri; Wilke, Mathias

2018-02-01

We present a comprehensive theory of critical spaces for the broad class of quasilinear parabolic evolution equations. The approach is based on maximal Lp-regularity in time-weighted function spaces. It is shown that our notion of critical spaces coincides with the concept of scaling invariant spaces in case that the underlying partial differential equation enjoys a scaling invariance. Applications to the vorticity equations for the Navier-Stokes problem, convection-diffusion equations, the Nernst-Planck-Poisson equations in electro-chemistry, chemotaxis equations, the MHD equations, and some other well-known parabolic equations are given.

Bifacial PV cell with reflector for stand-alone mast for sensor powering purposes

Science.gov (United States)

Jakobsen, Michael L.; Thorsteinsson, Sune; Poulsen, Peter B.; Riedel, N.; Rødder, Peter M.; Rødder, Kristin

2017-09-01

Reflectors to bifacial PV-cells are simulated and prototyped in this work. The aim is to optimize the reflector to specific latitudes, and particularly northern latitudes. Specifically, by using minimum semiconductor area the reflector must be able to deliver the electrical power required at the condition of minimum solar travel above the horizon, worst weather condition etc. We will test a bifacial PV-module with a retroreflector, and compare the output with simulations combined with local solar data.

Investigation of the crack in a reflector element of JRR-4

International Nuclear Information System (INIS)

2008-09-01

The JRR-4 (Japan Research Reactor No.4) has been used as a shared utilization facility for many researches since the first criticality in January 1965. A crack was ascertained on a weld area of one reflector element on December 28, 2007. The Department of Research Reactor and Tandem Accelerator set up an ad hoc working group of experts in the JAEA (Japan Atomic Energy Agency), and investigated cause of crack on the weld area. The following examinations were carried out; visual examination, dimensional examination, fractography examination and so on. It was concluded that the main cause of the crack is the swelling of graphite in the reflector element. The swelling must be due to neutron irradiation. We carried out a radiografical examination of the other reflector elements. As the result, we determined that many of them were not in a suitable state to be used because of swelling of graphite. The design of the new reflector elements should be carried out, based on the relation between the irradiation does and swelling rate, which has been obtained in these investigation. (author)

Strongly nonlinear parabolic variational inequalities.

Science.gov (United States)

Browder, F E; Brézis, H

1980-02-01

An existence and uniqueness result is established for a general class of variational inequalities for parabolic partial differential equations of the form partial differentialu/ partial differentialt + A(u) + g(u) = f with g nondecreasing but satisfying no growth condition. The proof is based upon a type of compactness result for solutions of variational inequalities that should find a variety of other applications.

Petrologic perspectives on tectonic evolution of a nascent basin (Okinawa Trough) behind Ryukyu Arc:A review

Institute of Scientific and Technical Information of China (English)

YAN Quanshu; SHI Xuefa

2014-01-01

Okinawa Trough is a back-arc, initial marginal sea basin, located behind the Ryukyu Arc-Trench System. The formation and evolution of the Okinawa Trough is intimately related to the subduction process of the Philippine Sea Plate beneath the Eurasian Plate since the late Miocene. The tectonic evolution of the trough is similar to other active back-arcs, such as the Mariana Trough and southern Lau Basin, all of which are experiencing the initial rifting and subsequent spreading process. This study reviews all petrologic and geochemical data of mafic volcanic lavas from the Okinawa Trough, Ryukyu Arc, and Philippine Sea Plate, combined with geophysical data to indicate the relationship between the subduction sources (input) and arc or back-arc magmas (output) in the Philippine Sea Plate-Ryukyu Arc-Okinawa Trough system (PROS). The results obtained showed that several components were variably involved in the petrogenesis of the Oki-nawa Trough lavas:sub-continental lithospheric mantle underlying the Eurasian Plate, Indian mid-oceanic ridge basalt (MORB)-type mantle, and Pacific MORB-type mantle. The addition of shallow aqueous fluids and deep hydrous melts from subducted components with the characteristics of Indian MORB-type mantle into the mantle source of lavas variably modifies the primitive mantle wedge beneath the Ryukyu and sub-continental lithospheric mantle (SCLM) beneath the Okinawa Trough. In the northeastern end of the trough and arc, instead of Indian MORB-type mantle, Pacific MORB-type mantle dominates the magma source. Along the strike of the Ryukyu Arc and Okinawa Trough, the systematic variations in trace element ratios and isotopic compositions reflect the first-order effect of variable subduction input on the magma source. In general, petrologic data, combined with geophysical data, imply that the Okinawa Trough is experiencing the“seafloor spreading”process in the southwest segment,“rift propagation”process in the middle seg-ment, and�

Development of an innovative reflector drive mechanism using magnetic repulsion force for 4S reactor

International Nuclear Information System (INIS)

Tsuji, K.; Watanabe, M.; Inagaki, H.; Nishikawa, A.; Takahashi, H.; Wakamatsu, M.; Matsumiya, H.; Nishiguchi, Y.

2001-01-01

A small sized fast reactor 4S: (Super Safe Small and Simple) which has a core of 10 - 30 years life time is controlled by reflectors. The reflector is required to be risen at very low speed to make up for the reactivity swing during operation. This report shows the development of an innovative reflector drive mechanism using magnetic repulsion force that can move at a several micrometer per one step. This drive mechanism has a passive shut down capability, and can eliminate reflector drive line. (author)

The Nova-Canton Trough and the Late Cretaceous evolution of the central Pacific

Science.gov (United States)

Joseph, Devorah; Taylor, Brain; Shor, Alexander N.; Yamazaki, Toshitsugu

Free-air gravity anomalies derived from satellite altimetry data show that the major Pacific fracture zones, from the Pau to Marquesas, are co-polar about an Euler pole located at 150.5°W, 34.6°S for the period preceding chron 33 and including a large portion of the Cretaceous Normal Superchron. They also show continuity of the Clipperton Fracture Zone through the Line Islands to the Nova-Canton ridge and trough; this Canton-Clipperton trend is co-polar to the same pole. Sidescan-sonar and bathymetry data in the Nova-Canton Trough region reveal N140°E-striking abyssal hill topography south of the N70°E-striking structures of the Nova-Canton Trough and crustal fabric striking normal to the trough (N160°E) to the north. We conclude that the Nova-Canton Trough is the Middle Cretaceous extension of the Clipperton Fracture Zone. We propose that the anomalous depths (7000-8400 m) of the trough between 167°30'-168°30'W are the result of a complex plate reorganization. Conjugate magnetic anomaly lineations M1-M3 in the Phoenix lineations between the Central Pacific Fracture Zone and the Phoenix Fracture Zone and the absence of lineations younger than anomaly M3 west of the Phoenix Fracture Zone suggest that spreading may have gradually ceased along the Pacific-Phoenix system from west to east. We infer that the remaining active segment of the Pacific-Phoenix spreading system after anomaly M1 time was the easternmost section of the Phoenix lineations. At ˜M0 time, the Pacific-Phoenix spreading axis stretched from lineated bathymetric depressions lying between 180°W and the Phoenix Islands to ˜168°W and included the western deep of the Nova-Canton Trough. We hypothesize that accretion terminated on the Pacific-Phoenix spreading axis shortly after M0 time and that the absence of an M0 isochron in the region between the eastern Phoenix lineations and the Nova-Canton Trough, or along the Nova-Canton Trough itself, may be due to a decrease in spreading rate prior to

Design of the Graphite Reflectors in Research Reactors

Energy Technology Data Exchange (ETDEWEB)

Lee, Jin Haeng; Cho, Yeong Garp; Kim, Tae Kyu; Kim, Jong In [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

2012-05-15

Graphite is often used as one of reflector materials for research reactors because of its low neutron absorption cross-section, good moderating properties, and relatively low and stable price. In addition, graphite has excellent properties at high temperatures, so it is widely used as a core material in high temperature reactors. However, its material characteristics such as strength, elastic modulus, thermal expansion coefficient, dimensional change, and thermal conductivity sensitively depend on neutron fluence, temperature, and its manufacturing process. In addition, the Wigner energy and the treatment of the graphite waste such as C-14 should also be considered. For the design of the graphite reflectors, it is therefore essential to understand the material characteristics of chosen graphite materials at given conditions. Especially, the dimensional changes and the thermal conductivity are very important factors to design the nuclear components using graphite as a nonstructural material. Hence, in this study, the material characteristics of graphite are investigated via some experiments in literature. Improving design methods for graphite reflectors in research reactors are then suggested to minimize the problems, and the advantages and disadvantages of each method are also discussed

Advanced photovoltaic-trough development

Energy Technology Data Exchange (ETDEWEB)

Spencer, R.; Yasuda, K.; Merson, B.

1982-04-01

The scope of the work on photvoltaic troughs includes analytical studies, hardware development, and component testing. Various aspects of the system have been optimized and improvements have been realized, particularly in the receiver and reflecting surface designs. An empirical system performance model has been developed that closely agrees with measured system performance. This in-depth study of single-axis reflecting linear focus photovoltaic concentrators will be very beneficial in the development of improved models for similar systems as well as other phtovoltaic concentrator designs.

Holocene tephra deposits in the northern Okinawa Trough

Institute of Scientific and Technical Information of China (English)

无

2006-01-01

The mineralogical and geochemical characteristics of sediments of Core CSH1, which was collected from the northern Okinawa Trough, indicate that large amounts of volcanic materials have deposited in the northern Okinawa Trough during the Holocene. On the basis of down-core variations in mineral and element contents of sediments, two layers in the uppermost section of Core CSH1 characterized by high quartz, Na2O, MnO, K2O, uranium contents and low contents of clay minerals, volatiles, Fe2O3, MgO, CaO and strontium, have been identified as the tephra deposits. Systematic grain-size measurements also suggest that sediments from the northern Okinawa Trough are made up of terrigenous materials and volcanic ashes with different proportion during the Holocene. The sediments of tephra layers in Core CSH1 show bi-modal patterns in grain-size distribution with modal grain-sizes of 74.3 and 7.81 μm,respectively. According to the radiocarbon dating on shells of zooplankton foraminifera, two tephra layers in Core CSH1, formed at 7 250 and 10 870 a BP (cal), approximately correspond to the K-Ah tephra [7 300 a BP (cal)] and the eruption of Kuju Volcano (12～10 ka BP), respectively.

Heavy reflector experiments in the IPEN/MB-01 reactor

International Nuclear Information System (INIS)

Santos, Adimir dos; Silva, Graciete Simoes de Andrade e; Mura, Luis Felipe; Fuga, Rinaldo; Jerez, Rogerio; Mendonca, Arlindo Gilson

2012-01-01

Full text: The heavy reflector experiments performed in the IPEN/MB-01 research reactor facility comprise a set of critical configurations employing the standard 28x26-fuel-rod configuration. The heavy reflector either Stainless Steel, Carbon Steel or Nickel plates was placed at one of the faces of the IPEN/MB-01 reactor. Criticality is achieved by inserting the control banks BC1 and BC2 to the critical position. 32 plates around 0.3 mm thick were used in the experiment. The chosen distance between last fuel rod row and the first laminate for both type of laminates was 5.5 mm. Considering initially the SS case, the experimental data reveal that the reactivity decreases up to the sixth plate and after that it increases, becomes nearly zero (which was equivalent to initial zero excess reactivity with zero plates) for the 21 plates case and reaches a value of 154.91 pcm when the whole set of 32 plates are inserted in the reflector. This is a very striking result because it demonstrates that when all 32 plates are inserted in the reflector there is a net gain of reactivity. The reactivity behavior demonstrates all the physics events already mentioned in this work. When the number of plates are small (around 6), the neutron absorption in the plates is more important than the neutron reflection and the reactivity decreases. This condition holds up to a point where the neutron reflection becomes more important than the neutron absorption in the plates and the reactivity increases. The experimental data for the Carbon Steel and Nickel case shows the main features of the SS case, but for the Carbon Steel case the reactivity gain is small, thus demonstrating that Carbon Steel or essentially iron has not the reflector capability as the SS laminates do. The measured data of Nickel plates show a higher reactivity gain, thus demonstrating that Nickel is a good reflector. The theoretical analysis employing MCNP5 and ENDF/B-VII.0 show that the SS calculated results are in a good

INERTIAL MANIFOLDS FOR NONAUTONOMOUS SEMILINEAR PARABOLIC PARTIAL DIFFERENTIAL EQUATIONS WITH TIME DELAYS

Institute of Scientific and Technical Information of China (English)

无

2006-01-01

The present paper deals with the long-time behavior of a class of nonautonomous retarded semilinear parabolic differential equations. When the time delays are small enough and the spectral gap conditions hold, the inertial manifolds of the nonautonomous retard parabolic equations are constructed by using the Lyapunov-Perron method.

Solutions to variational inequalities of parabolic type

Science.gov (United States)

Zhu, Yuanguo

2006-09-01

The existence of strong solutions to a kind of variational inequality of parabolic type is investigated by the theory of semigroups of linear operators. As an application, an abstract semi permeable media problem is studied.

Solar thermal power plants

International Nuclear Information System (INIS)

Schnatbaum, L.

2009-01-01

The solar thermal power plant technology, the opportunities it presents and the developments in the market are outlined. The focus is on the technology of parabolic trough power plants, a proven technology for solar power generation on a large scale. In a parabolic trough power plant, trough-shaped mirrors concentrate the solar irradiation onto a pipe in the focal line of the collector. The thermal energy thus generated is used for electricity generation in a steam turbine. Parabolic trough plants can be combined with thermal storage and fossil or biomass fired heat exchangers to generate electricity even when the sun is not shining. Solar Millennium AG in Erlangen has developed the first power plant of this kind in Europe. After two years of construction the plant started operation in Southern Spain in 2008. This one and its sister projects are important steps leading the way for the whole market. The paper also covers the technological challenges, the key components used and the research and development activities concerning this technology. Solar thermal power plants are ideal for covering peak and medium loads in power grids. In hybrid operation they can also cover base-load. The Solar Chimney power plant, another striking technology for the conversion of solar into electric energy, is described briefly. The paper concludes with a look at the future - the import of solar energy from the deserts of North Africa to central Europe. (author)

Uranium Enrichment Reduction in the Prototype Gen-IV Sodium-Cooled Fast Reactor (PGSFR with PBO Reflector

Directory of Open Access Journals (Sweden)

Chihyung Kim

2016-04-01

Full Text Available The Korean Prototype Gen-IV sodium-cooled fast reactor (PGSFR is supposed to be loaded with a relatively-costly low-enriched U fuel, while its envisaged transuranic fuels are not available for transmutation. In this work, the U-enrichment reduction by improving the neutron economy is pursued to save the fuel cost. To improve the neutron economy of the core, a new reflector material, PbO, has been introduced to replace the conventional HT9 reflector in the current PGSFR core. Two types of PbO reflectors are considered: one is the conventional pin-type and the other one is an inverted configuration. The inverted PbO reflector design is intended to maximize the PbO volume fraction in the reflector assembly. In addition, the core radial configuration is also modified to maximize the performance of the PbO reflector. For the baseline PGSFR core with several reflector options, the U enrichment requirement has been analyzed and the fuel depletion analysis is performed to derive the equilibrium cycle parameters. The linear reactivity model is used to determine the equilibrium cycle performances of the core. Impacts of the new PbO reflectors are characterized in terms of the cycle length, neutron leakage, radial power distribution, and operational fuel cost.

Uranium enrichment reduction in the Prototype Gen-IV sodium-cooled fast reactor (PGSFR) with PBO reflector

Energy Technology Data Exchange (ETDEWEB)

Hartanto, Donny; Kim, Chi Hyung; Kim, Yong Hee [Dept. of Nuclear and Quantum Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon (Korea, Republic of)

2016-04-15

The Korean Prototype Gen-IV sodium-cooled fast reactor (PGSFR) is supposed to be loaded with a relatively-costly low-enriched U fuel, while its envisaged transuranic fuels are not available for transmutation. In this work, the U-enrichment reduction by improving the neutron economy is pursued to save the fuel cost. To improve the neutron economy of the core, a new reflector material, PbO, has been introduced to replace the conventional HT9 reflector in the current PGSFR core. Two types of PbO reflectors are considered: one is the conventional pin-type and the other one is an inverted configuration. The inverted PbO reflector design is intended to maximize the PbO volume fraction in the reflector assembly. In addition, the core radial configuration is also modified to maximize the performance of the PbO reflector. For the baseline PGSFR core with several reflector options, the U enrichment requirement has been analyzed and the fuel depletion analysis is performed to derive the equilibrium cycle parameters. The linear reactivity model is used to determine the equilibrium cycle performances of the core. Impacts of the new PbO reflectors are characterized in terms of the cycle length, neutron leakage, radial power distribution, and operational fuel cost.

Convergence of shock waves between conical and parabolic boundaries

Energy Technology Data Exchange (ETDEWEB)

Yanuka, D.; Zinowits, H. E.; Antonov, O.; Efimov, S.; Virozub, A.; Krasik, Ya. E. [Physics Department, Technion, Haifa 32000 (Israel)

2016-07-15

Convergence of shock waves, generated by underwater electrical explosions of cylindrical wire arrays, between either parabolic or conical bounding walls is investigated. A high-current pulse with a peak of ∼550 kA and rise time of ∼300 ns was applied for the wire array explosion. Strong self-emission from an optical fiber placed at the origin of the implosion was used for estimating the time of flight of the shock wave. 2D hydrodynamic simulations coupled with the equations of state of water and copper showed that the pressure obtained in the vicinity of the implosion is ∼7 times higher in the case of parabolic walls. However, comparison with a spherical wire array explosion showed that the pressure in the implosion vicinity in that case is higher than the pressure in the current experiment with parabolic bounding walls because of strong shock wave reflections from the walls. It is shown that this drawback of the bounding walls can be significantly minimized by optimization of the wire array geometry.

Collapsible structure for an antenna reflector

Science.gov (United States)

Trubert, M. R. (Inventor)

1973-01-01

A collapsible support for an antenna reflector for use in supporting spacecraft antennas is described. The support has a regid base and a number of struts which are pivoted at the base. The deployment of the struts and their final configuration for supporting the antenna are illustrated.

New two-port multimode interference reflectors

NARCIS (Netherlands)

Kleijn, E.; Smit, M.K.; Wale, M.J.; Leijtens, X.J.M.

2012-01-01

Multi-mode interference reflectors (MIRs) are versatile components. Two new MIR designs with a fixed 50/50 reflection to transmission ratio are introduced. Measurements on these new devices and on devices similar to those in [1] are presented and compared to the design values. Measured losses are

Deployable reflector configurations. [for space telescope

Science.gov (United States)

Meinel, A. B.; Meinel, M. P.; Woolf, N. J.

1983-01-01

Both the theoretical reasons for considering a non-circular format for the Large Deployable Reflector, and a potentially realizable concept for such a device, are discussed. The optimum systems for diffraction limited telescopes with incoherent detection have either a single filled aperture, or two such apertures as an interferometer to synthesize a larger aperture. For a single aperture of limited area, a reflector in the form of a slot can be used to give increased angular resolution. It is shown how a 20 x 8 meter telescope can be configured to fit the Space Shuttle bay, and deployed with relatively simple operations. The relationship between the sunshield design and the inclination of the orbit is discussed. The possible use of the LDR as a basic module to permit the construction of supergiant space telescopes and interferometers both for IR/submm studies and for the entire ultraviolet through mm wave spectral region is discussed.

Integrated parabolic nanolenses on MicroLED color pixels

Science.gov (United States)

Demory, Brandon; Chung, Kunook; Katcher, Adam; Sui, Jingyang; Deng, Hui; Ku, Pei-Cheng

2018-04-01

A parabolic nanolens array coupled to the emission of a nanopillar micro-light emitting diode (LED) color pixel is shown to reduce the far field divergence. For a blue wavelength LED, the total emission is 95% collimated within a 0.5 numerical aperture zone, a 3.5x improvement over the same LED without a lens structure. This corresponds to a half-width at half-maximum (HWHM) line width reduction of 2.85 times. Using a resist reflow and etchback procedure, the nanolens array dimensions and parabolic shape are formed. Experimental measurement of the far field emission shows a HWHM linewidth reduction by a factor of 2x, reducing the divergence over the original LED.

Thin Film Flat Panel Off-Axis Solar Concentrator with Flux Distribution, Phase I

Data.gov (United States)

National Aeronautics and Space Administration — Relatively small concentric thin film FRESNEL lenses and fresnel-like Multiple Parabolic Reflecting Surface (MPRS) reflectors have been successfully produced from...

Nonlinear anisotropic parabolic equations in Lm

Directory of Open Access Journals (Sweden)

Fares Mokhtari

2014-01-01

Full Text Available In this paper, we give a result of regularity of weak solutions for a class of nonlinear anisotropic parabolic equations with lower-order term when the right-hand side is an Lm function, with m being ”small”. This work generalizes some results given in [2] and [3].

High-resolution records of thermocline in the Okinawa Trough since about 10000 aBP

Institute of Scientific and Technical Information of China (English)

无

2001-01-01

The present paper uses planktonic foraminifera and their stableisotopes to study the changes in the depth of thermocline (DOT) in the Okinawa Trough since the last 10000 a based on the analysis of Core B-3GC in the northern Okinawa Trough, together with that of the core in the southern Okinawa Trough. As results show, the thermocline was shallow before 6400 aBP, and deepened afterward, then became shallow again from 4000 to 2000 aBP. The DOT fluctuations display a positive correlation with those of sea surface temperature (SST). In addition, the changes in the northern Okinawa Trough are similar to those in the southern trough, implying a possible connection with the variation of the Kuroshio Current. The changes of SST and DOT suggest that the Kuroshio Current changed its intensity or main axis from 4000 to 2000 aBP and around about 6400 aBP respectively. Moreover, the changes of DOT from 8200 to 6400 aBP may indicate a gradual intensification of the Kuroshio Current.

New sidescan sonar and gravity evidence that the Nova-Canton Trough is a fracture zone

Science.gov (United States)

Joseph, Devorah; Taylor, Brian; Shor, Alexander N.

1992-05-01

A 1990 sidescan sonar survey in the eastern region of the Nova-Canton Trough mapped 138°-striking abyssal-hill fabric trending into 70°-striking trough structures. The location and angle of intersection of the abyssal hills with the eastern Nova-Canton Trough effectively disprove a spreading-center origin of this feature. Free-air gravity anomalies derived from satellite altimetry data show continuity, across the Line Islands, of the Nova-Canton Trough with the Clipperton Fracture Zone. The Canton-Clipperton trend is copolar, about a pole at 30°S, 152°W, with other coeval Pacific-Farallon fracture-zone segments, from the Pau to Marquesas fracture zones. This copolarity leads us to postulate a Pacific-Farallon spreading pattern for the magnetic quiet zone region north and east of the Manihiki Plateau, with the Nova-Canton Trough originating as a transform fault in this system.

Vertical reflector for bifacial PV-panels

DEFF Research Database (Denmark)

Jakobsen, Michael Linde; Thorsteinsson, Sune; Poulsen, Peter Behrensdorff

2016-01-01

Bifacial solar modules offer an interesting price/performance ratio, and much work has been focused on directing the ground albedo to the back of the solar cells. In this work we design and develop a reflector for a vertical bifacial panel, with the objective to optimize the energy harvest...

Comparison of Different Technologies for Integrated Solar Combined Cycles: Analysis of Concentrating Technology and Solar Integration

Directory of Open Access Journals (Sweden)

Antonio Rovira

2018-04-01

Full Text Available This paper compares the annual performance of Integrated Solar Combined Cycles (ISCCs using different solar concentration technologies: parabolic trough collectors (PTC, linear Fresnel reflectors (LFR and central tower receiver (CT. Each solar technology (i.e. PTC, LFR and CT is proposed to integrate solar energy into the combined cycle in two different ways. The first one is based on the use of solar energy to evaporate water of the steam cycle by means of direct steam generation (DSG, increasing the steam production of the high pressure level of the steam generator. The other one is based on the use of solar energy to preheat the pressurized air at the exit of the gas turbine compressor before it is introduced in the combustion chamber, reducing the fuel consumption. Results show that ISCC with DSG increases the yearly production while solar air heating reduces it due to the incremental pressure drop. However, air heating allows significantly higher solar-to-electricity efficiencies and lower heat rates. Regarding the solar technologies, PTC provides the best thermal results.

Global Carleman estimates for degenerate parabolic operators with applications

CERN Document Server

Cannarsa, P; Vancostenoble, J

2016-01-01

Degenerate parabolic operators have received increasing attention in recent years because they are associated with both important theoretical analysis, such as stochastic diffusion processes, and interesting applications to engineering, physics, biology, and economics. This manuscript has been conceived to introduce the reader to global Carleman estimates for a class of parabolic operators which may degenerate at the boundary of the space domain, in the normal direction to the boundary. Such a kind of degeneracy is relevant to study the invariance of a domain with respect to a given stochastic diffusion flow, and appears naturally in climatology models.

Development of an environment-insensitive PWR radial reflector model applicable to modern nodal reactor analysis method

International Nuclear Information System (INIS)

Mueller, E.M.

1989-05-01

This research is concerned with the development and analysis of methods for generating equivalent nodal diffusion parameters for the radial reflector of a PWR. The requirement that the equivalent reflector data be insensitive to changing core conditions is set as a principle objective. Hence, the environment dependence of the currently most reputable nodal reflector models, almost all of which are based on the nodal equivalence theory homgenization methods of Koebke and Smith, is investigated in detail. For this purpose, a special 1-D nodal equivalence theory reflector model, called the NGET model, is developed and used in 1-D and 2-D numerical experiments. The results demonstrate that these modern radial reflector models exhibit sufficient sensitivity to core conditions to warrant the development of alternative models. A new 1-D nodal reflector model, which is based on a novel combination of the nodal equivalence theory and the response matrix homogenization methods, is developed. Numerical results varify that this homogenized baffle/reflector model, which is called the NGET-RM model, is highly insensitive to changing core conditions. It is also shown that the NGET-RM model is not inferior to any of the existing 1-D nodal reflector models and that it has features which makes it an attractive alternative model for multi-dimensional reactor analysis. 61 refs., 40 figs., 36 tabs

Development and Performance Evaluation of Light Shelves Using Width-Adjustable Reflectors

Directory of Open Access Journals (Sweden)

Heangwoo Lee

2018-01-01

Full Text Available In recent years, there has been an increase in the consumption of energy for lighting purposes, which has led to an increase in the number of studies being conducted on this subject. Most studies have focused on light shelves, which are daylighting systems used for reducing the lighting energy required for the interiors of buildings. However, the existing light shelves cannot actively deal with external environmental factors, which often lead to an infringement of the right to light during the night when the performance of the light shelf deteriorates. Therefore, in this study, we propose a light shelf with a width-adjustable reflector and verify its validity using a testbed. The reflector of the proposed light shelf system is modularized so that the length can be adjusted in stages. The optimum width of the light shelf is calculated in terms of the energy reduction and uniformity ratio improvement, and the obtained optimum width is varied depending on the season. We find that the width-adjustable reflector can save 20% and 21.6% more lighting energy than light shelves with fixed reflector widths of 0.3 m and 0.6 m, respectively.

Design improvement and performance evaluation of solar photocatalytic reactor for industrial effluent treatment.

Science.gov (United States)

Nair, Ranjith G; Bharadwaj, P J; Samdarshi, S K

2016-12-01

This work reports the details of the design components and materials used in a linear compound parabolic trough reactor constructed with an aim to use the photocatalyst for solar photocatalytic applications. A compound parabolic trough reactor has been designed and engineered to exploit both UV and visible part of the solar irradiation. The developed compound parabolic trough reactor could receive almost 88% of UV radiation along with a major part of visible radiation. The performance of the reactor has been evaluated in terms of degradation of a probe pollutant using the parameters such as rate constant, residence time and photonic efficiency. An attempt has been made to assess the performance in different ranges of solar spectrum. Finally the developed reactor has been employed for the photocatalytic treatment of a paper mill effluent using Degussa P25 as the photocatalyst. The paper mill effluent collected from Nagaon paper mill, Assam, India has been treated under both batch mode and continuous mode using Degussa P25 photocatalyst under artificial and natural solar radiation, respectively. The photocatalytic degradation kinetics of the paper mill effluent has been determined using the reduction in total organic carbon (TOC) values of the effluent. Copyright © 2015 Elsevier Inc. All rights reserved.

Compact Antenna Range

Data.gov (United States)

Federal Laboratory Consortium — Facility consists of a folded compact antenna range including a computer controlled three axis position table, parabolic reflector and RF sources for the measurement...

Numerical performance of the parabolized ADM formulation of general relativity

International Nuclear Information System (INIS)

Paschalidis, Vasileios; Hansen, Jakob; Khokhlov, Alexei

2008-01-01

In a recent paper [Vasileios Paschalidis, Phys. Rev. D 78, 024002 (2008).], the first coauthor presented a new parabolic extension (PADM) of the standard 3+1 Arnowitt, Deser, Misner (ADM) formulation of the equations of general relativity. By parabolizing first-order ADM in a certain way, the PADM formulation turns it into a well-posed system which resembles the structure of mixed hyperbolic-second-order parabolic partial differential equations. The surface of constraints of PADM becomes a local attractor for all solutions and all possible well-posed gauge conditions. This paper describes a numerical implementation of PADM and studies its accuracy and stability in a series of standard numerical tests. Numerical properties of PADM are compared with those of standard ADM and its hyperbolic Kidder, Scheel, Teukolsky (KST) extension. The PADM scheme is numerically stable, convergent, and second-order accurate. The new formulation has better control of the constraint-violating modes than ADM and KST.

First Middle East Aircraft Parabolic Flights for ISU Participant Experiments

Science.gov (United States)

Pletser, Vladimir; Frischauf, Norbert; Cohen, Dan; Foster, Matthew; Spannagel, Ruven; Szeszko, Adam; Laufer, Rene

2017-06-01

Aircraft parabolic flights are widely used throughout the world to create microgravity environment for scientific and technology research, experiment rehearsal for space missions, and for astronaut training before space flights. As part of the Space Studies Program 2016 of the International Space University summer session at the Technion - Israel Institute of Technology, Haifa, Israel, a series of aircraft parabolic flights were organized with a glider in support of departmental activities on `Artificial and Micro-gravity' within the Space Sciences Department. Five flights were organized with manoeuvres including several parabolas with 5 to 6 s of weightlessness, bank turns with acceleration up to 2 g and disorientation inducing manoeuvres. Four demonstration experiments and two experiments proposed by SSP16 participants were performed during the flights by on board operators. This paper reports on the microgravity experiments conducted during these parabolic flights, the first conducted in the Middle East for science and pedagogical experiments.

Global shielding analysis of the 2-element ANS core and reflector with photoneutrons

International Nuclear Information System (INIS)

Bucholz, J.A.

1996-01-01

This paper describes the initial global 2-D shielding analyses for the 2-element, heavy-water cooled and reflected Advanced Neutron Source reactor which was to have been built in Oak Ridge, Tennessee. The portion of the system analyzed encompassed the highly enriched core, the 1.5-m-thick heavy-water reflector, the aluminum reflector vessel, and the first 0.2 m of light water beyond the reflector vessel. While some results are presented, this paper focuses primarily on the lessons learned during the analysis of this rather unique system

O+ trough zones in the polar cap ionosphere-magnetosphere coupling region

Science.gov (United States)

Horwitz, James; Zeng, Wen; Jaafari, Fajer

Regions of low-density troughs in O+ have been observed at 1 RE altitude in the polar cap ionosphere-magnetosphere region by the Thermal Ion Dynamics Experiment(TIDE) on the POLAR spacecraft. In this presentation, the UT Arlington Dynamic Fluid-Kinetic (DyFK) code is employed to investigate the formation of such O+ density troughs. We utilize convection paths of flux tubes in the high-latitude region as prescribed by an empirical convection model with solar wind inputs to track the evolution of ionospheric plasma transport and in particular O+ densities along these tubes with time/space. The flux tubes are subjected to auroral processes of precipitation and wave-driven ion heating when they pass through the auroral oval, which tends to elevate the plasma densities in these tubes. When the F-regions of such tubes traverse locations where the F-region is in darkness, recombination there causes the higher-altitude regions to drain and the densities to decline throughout. Owing to the varying effects of these processes, significant and low trough-like densities at higher altitudes developed along these flux tubes. The modeled densities near 6000 km altitudes will be compared with multiple POLAR passes featuring POLAR/TIDE-measured O+ densities for inside and outside of such trough regions.

Iterative Methods for Solving Nonlinear Parabolic Problem in Pension Saving Management

Science.gov (United States)

Koleva, M. N.

2011-11-01

In this work we consider a nonlinear parabolic equation, obtained from Riccati like transformation of the Hamilton-Jacobi-Bellman equation, arising in pension saving management. We discuss two numerical iterative methods for solving the model problem—fully implicit Picard method and mixed Picard-Newton method, which preserves the parabolic characteristics of the differential problem. Numerical experiments for comparison the accuracy and effectiveness of the algorithms are discussed. Finally, observations are given.

Temperature Performance Evaluation of Parabolic Dishes Covered ...

African Journals Online (AJOL)

Aweda

The parabolic dish with glass material gave the highest temperature of .... 3: Second day variation temperature and time using different materials. 8. 10 .... the sun rays at that particular time. ... especially between 11:00 am and 3:00 pm when.

Processes influencing differences in Arctic and Antarctic Trough Mouth Fan sedimentology

OpenAIRE

Gales, J; Hillenbrand, C-D; Larter, R; Laberg, J-S; Melles, M; Benetti, S; Passchier, S

2018-01-01

Trough Mouth Fans (TMFs) are sediment depocentres that form along high-latitude continental margins at the mouths of some cross-shelf troughs. They reflect the dynamics of past ice sheets over multiple glacial cycles and processes operating on (formerly) glaciated continental shelves and slopes, such as erosion, reworking, transport and deposition. The similarities and differences in TMF morphology and formation processes of the Arctic and Antarctic regions remain poorly constrained. Here, we...

Calculation of the illuminance distribution in the focal spot of a focusing system taking into account aberrations in this system and divergence of a focused laser beam

International Nuclear Information System (INIS)

Gitin, Andrey V

2007-01-01

The dependence of the focal-spot size of a 'deep' parabolic mirror reflector on the laser-beam divergence is analysed by the method of elementary reflections. The dependence of the focal-beam diameter of an ideal focusing optical system on the laser-beam parameters is described. The expression is obtained for calculating the illumination distribution in the focal spot of a 'deep' mirror reflector which takes into account both aberrations and light-gathering power of the reflector and the divergence of a focused laser beam. (optical systems)

Shaping Single Offset Reflector Antennas Using Local Axis-Displaced Confocal Quadrics

Directory of Open Access Journals (Sweden)

Rafael A. Penchel

2016-01-01

Full Text Available This work investigates a novel numerical procedure for the solution of an exact formulation for the Geometrical Optics synthesis of a single reflector antenna by simultaneously imposing Snell’s Law and Conservation of Energy in a tube of rays, yielding a second-order nonlinear partial differential equation of Monge-Ampère type, which can be solved as a boundary value problem. The investigation explores the interpolating properties of confocal quadrics to locally represent the shaped reflector surface. It allows the partial derivatives involved in the formulation to be analytically expressed. To illustrate the method, two examples of offset single reflectors shaped to radiate a Gaussian power density within a superelliptical contoured beam are presented. The results are validated by Physical Optics analysis with equivalent edge currents.

Spike-adding in parabolic bursters: The role of folded-saddle canards

Science.gov (United States)

Desroches, Mathieu; Krupa, Martin; Rodrigues, Serafim

2016-09-01

The present work develops a new approach to studying parabolic bursting, and also proposes a novel four-dimensional canonical and polynomial-based parabolic burster. In addition to this new polynomial system, we also consider the conductance-based model of the Aplysia R15 neuron known as the Plant model, and a reduction of this prototypical biophysical parabolic burster to three variables, including one phase variable, namely the Baer-Rinzel-Carillo (BRC) phase model. Revisiting these models from the perspective of slow-fast dynamics reveals that the number of spikes per burst may vary upon parameter changes, however the spike-adding process occurs in an explosive fashion that involves special solutions called canards. This spike-adding canard explosion phenomenon is analysed by using tools from geometric singular perturbation theory in tandem with numerical bifurcation techniques. We find that the bifurcation structure persists across all considered systems, that is, spikes within the burst are incremented via the crossing of an excitability threshold given by a particular type of canard orbit, namely the true canard of a folded-saddle singularity. However there can be a difference in the spike-adding transitions in parameter space from one case to another, according to whether the process is continuous or discontinuous, which depends upon the geometry of the folded-saddle canard. Using these findings, we construct a new polynomial approximation of the Plant model, which retains all the key elements for parabolic bursting, including the spike-adding transitions mediated by folded-saddle canards. Finally, we briefly investigate the presence of spike-adding via canards in planar phase models of parabolic bursting, namely the theta model by Ermentrout and Kopell.

Degenerate parabolic stochastic partial differential equations

Czech Academy of Sciences Publication Activity Database

span class="emphasis">Hofmanová, Martinaspan>

2013-01-01

Roč. 123, č. 12 (2013), s. 4294-4336 ISSN 0304-4149 R&D Projects: GA ČR GAP201/10/0752 Institutional support: RVO:67985556 Keywords : kinetic solutions * degenerate stochastic parabolic equations Subject RIV: BA - General Mathematics Impact factor: 1.046, year: 2013 http://library.utia.cas.cz/separaty/2013/SI/hofmanova-0397241.pdf

A parabolic mirror x-ray collimator

Science.gov (United States)

Franks, A.; Jackson, K.; Yacoot, A.

2000-05-01

A robust and stable x-ray collimator has been developed to produce a parallel beam of x-rays by total external reflection from a parabolic mirror. The width of the gold-coated silica mirror varies along its length, which allows it to be bent from a plane surface into a parabolic form by application of unequal bending forces at its ends. A family of parabolas of near constant focal length can be formed by changing the screw-applied bending force, thus allowing the collimator to cater for a range of wavelengths by the turning of a screw. Even with radiation with a wavelength as short as that as Mo Kicons/Journals/Common/alpha" ALT="alpha" ALIGN="TOP"/> 1 (icons/Journals/Common/lambda" ALT="lambda" ALIGN="TOP"/> = 0.07 nm), a gain in flux by a factor of 5.5 was achieved. The potential gain increases with wavelength, e.g. for Cu Kicons/Journals/Common/alpha" ALT="alpha" ALIGN="TOP"/> 1 radiation this amounts to over a factor of ten.

Non-uniformly sampled grids in double pole coordinate system for freeform reflector construction

Science.gov (United States)

Ma, Donglin; Pacheco, Shaun; Feng, Zexin; Liang, Rongguang

2015-08-01

We propose a new method to design freeform reflectors by nonuniformly sampling the source intensity distribution in double pole coordinate system. In double pole coordinate system, there is no pole for the whole hemisphere because both poles of the spherical coordinate system are moved to southernmost point of the sphere and overlapped together. With symmetric definition of both angular coordinates in the modified double pole coordinate system, a better match between the source intensity distribution and target irradiance distribution can be achieved for reflectors with large acceptance solid angle, leading to higher light efficiency and better uniformity on the target surface. With non-uniform sampling of the source intensity, we can design circular freeform reflector to obtain uniform rectangular illumination pattern. Aided by the feedback optimization, the freeform reflector can achieve the collection efficiency for ideal point source over 0.7 and relative standard deviation (RSD) less than 0.1.

Reflector automatic acquisition and pointing based on auto-collimation theodolite

Science.gov (United States)

Luo, Jun; Wang, Zhiqian; Wen, Zhuoman; Li, Mingzhu; Liu, Shaojin; Shen, Chengwu

2018-01-01

An auto-collimation theodolite (ACT) for reflector automatic acquisition and pointing is designed based on the principle of autocollimators and theodolites. First, the principle of auto-collimation and theodolites is reviewed, and then the coaxial ACT structure is developed. Subsequently, the acquisition and pointing strategies for reflector measurements are presented, which first quickly acquires the target over a wide range and then points the laser spot to the charge coupled device zero position. Finally, experiments are conducted to verify the acquisition and pointing performance, including the calibration of the ACT, the comparison of the acquisition mode and pointing mode, and the accuracy measurement in horizontal and vertical directions. In both directions, a measurement accuracy of ±3″ is achieved. The presented ACT is suitable for automatic pointing and monitoring the reflector over a small scanning area and can be used in a wide range of applications such as bridge structure monitoring and cooperative target aiming.

Hybrid integrated single-wavelength laser with silicon micro-ring reflector

Science.gov (United States)

Ren, Min; Pu, Jing; Krishnamurthy, Vivek; Xu, Zhengji; Lee, Chee-Wei; Li, Dongdong; Gonzaga, Leonard; Toh, Yeow T.; Tjiptoharsono, Febi; Wang, Qian

2018-02-01

A hybrid integrated single-wavelength laser with silicon micro-ring reflector is demonstrated theoretically and experimentally. It consists of a heterogeneously integrated III-V section for optical gain, an adiabatic taper for light coupling, and a silicon micro-ring reflector for both wavelength selection and light reflection. Heterogeneous integration processes for multiple III-V chips bonded to an 8-inch Si wafer have been developed, which is promising for massive production of hybrid lasers on Si. The III-V layer is introduced on top of a 220-nm thick SOI layer through low-temperature wafer-boning technology. The optical coupling efficiency of >85% between III-V and Si waveguide has been achieved. The silicon micro-ring reflector, as the key element of the hybrid laser, is studied, with its maximized reflectivity of 85.6% demonstrated experimentally. The compact single-wavelength laser enables fully monolithic integration on silicon wafer for optical communication and optical sensing application.

Design and measured performances of a plane reflector augmented box-type solar-energy cooker

International Nuclear Information System (INIS)

Ekechukwu, O.V.

2001-06-01

The design philosophy, construction and measured performances of a plane-reflector augmented box-type solar-energy cooker are presented. The experimental solar cooker consists of an aluminum plate absorber painted matt black and a double-glazed lid. The bottom and sides are lagged with fibreglass wool insulator. The reflector consists of a wooden-framed commercially-available specular plane mirror which is sized to form a cover for the box when not in use. Provision is made for four cooking vessels each capable of holding up to 1 kg of water. Results of thermal performance tests show stagnation absorber plate temperatures of 138 deg. C and 119 deg. C for the cooker with and without the plane reflector in place, respectively. Boiling times of 60 minutes (3600 seconds) and 70 minutes (4200 seconds) for 1 kg of water, for the cooker with and without the reflector in place, respectively, were recorded. The solar cooker performance has been rated using the first figure of merit (F 1 ) on the no-load test and the second figure of merit (F 2 ) on the sensible heat tests. Predicted water boiling times using the two figures of merit compared favourable with measured values. The performance of the cooker with the plane reflector in place was improved tremendously compared to that without the reflector in place. (author)

Moving interfaces and quasilinear parabolic evolution equations

CERN Document Server

Prüss, Jan

2016-01-01

In this monograph, the authors develop a comprehensive approach for the mathematical analysis of a wide array of problems involving moving interfaces. It includes an in-depth study of abstract quasilinear parabolic evolution equations, elliptic and parabolic boundary value problems, transmission problems, one- and two-phase Stokes problems, and the equations of incompressible viscous one- and two-phase fluid flows. The theory of maximal regularity, an essential element, is also fully developed. The authors present a modern approach based on powerful tools in classical analysis, functional analysis, and vector-valued harmonic analysis. The theory is applied to problems in two-phase fluid dynamics and phase transitions, one-phase generalized Newtonian fluids, nematic liquid crystal flows, Maxwell-Stefan diffusion, and a variety of geometric evolution equations. The book also includes a discussion of the underlying physical and thermodynamic principles governing the equations of fluid flows and phase transitions...

Wind load design methods for ground-based heliostats and parabolic dish collectors

Energy Technology Data Exchange (ETDEWEB)

Peterka, J A; Derickson, R G [Colorado State Univ., Fort Collins, CO (United States). Fluid Dynamics and Diffusion Lab.

1992-09-01

The purpose of this design method is to define wind loads on flat heliostat and parabolic dish collectors in a simplified form. Wind loads are defined for both mean and peak loads accounting for the protective influence of upwind collectors, wind protective fences, or other wind-blockage elements. The method used to define wind loads was to generalize wind load data obtained during tests on model collectors, heliostats or parabolic dishes, placed in a modeled atmospheric wind in a boundary-layer wind-tunnel at Colorado State University. For both heliostats and parabolic dishes, loads are reported for solitary collectors and for collectors as elements of a field. All collectors were solid with negligible porosity; thus the effects of porosity in the collectors is not addressed.

The upgrade of intense pulsed neutron source (IPNS) through the change of coolant and reflector

CERN Document Server

Baek, I C; Iverson, E B

2002-01-01

The current intense pulsed neutron source (IPNS) depleted uranium target is cooled by light water. The inner reflector material is graphite and the outer reflector material is beryllium. The presence of H sub 2 O in the target moderates neutrons and leads to a higher absorption loss in the target than is necessary. D sub 2 O coolant in the small quantities required minimizes this effect. We have studied the possible improvement in IPNS beam fluxes that would result from changing the coolant from H sub 2 O to D sub 2 O and the inner reflector from graphite to beryllium. Neutron intensities were calculated for directions normal to the viewed surface of each moderator for four different cases of combinations of target coolant and reflector materials. The simulations reported here were performed using the MCNPX (version 2.1.5) computer program. Our results show that substantial gains in neutron beam intensities can be achieved by appropriate combination of target coolant and reflector materials. The combination o...

User manual for semi-circular compact range reflector code: Version 2

Science.gov (United States)

Gupta, Inder J.; Burnside, Walter D.

1987-01-01

A computer code has been developed at the Ohio State University ElectroScience Laboratory to analyze a semi-circular paraboloidal reflector with or without a rolled edge at the top and a skirt at the bottom. The code can be used to compute the total near field of the reflector or its individual components at a given distance from the center of the paraboloid. The code computes the fields along a radial, horizontal, vertical or axial cut at that distance. Thus, it is very effective in computing the size of the sweet spot for a semi-circular compact range reflector. This report describes the operation of the code. Various input and output statements are explained. Some results obtained using the computer code are presented to illustrate the code's capability as well as being samples of input/output sets.

Measuring device for bending of beryllium reflector

International Nuclear Information System (INIS)

Nishida, Seiri; Sakamoto, Naoki.

1994-01-01

The device of the present invention can measure bending of a beryllium reflector formed in a reactor core of a nuclear reactor by a relatively easy operation. Namely, a sensor portion comprises a long-support that can be inserted to a fuel element-insertion hole disposed in the reactor and a plurality of distance sensors disposed in a longitudinal direction of the support. A supersonic wave sensor which is advantageous in the heat resistance, the size and the accuracy and can conduct measurement in water relatively easily is used as the distance sensors. However, other sensors, instead of the sensor described above, may also be used. The plurality of distance sensors detect the bending amount of the beryllium reflector in the longitudinal direction by such an easy operation of inserting such a sensor portion to the fuel element-insertion hole upon exchange of fuel elements. (I.S.)

REVIEW ARTICLE: Bioluminescent signals and the role of reflectors

Science.gov (United States)

Herring, Peter J.

2000-11-01

Organisms in a well lit environment use optical signals derived from the selective reflection of ambient light. In a dim or dark environment it is very difficult (because of low photon numbers) to detect the contrast between light reflected from the organism and that from the background, and many organisms use bioluminescent signals instead. The use of such signals on land is largely restricted to sexual signalling by the luminous beetles, but in the deep ocean their use is widespread, involving both many different organisms and a range of uses which parallel those of reflective signals on land. Some bioluminescent signals rely almost entirely on an optically unmodified light source (e.g. a secretion) but others depend upon complex optical structures, particularly reflectors, in the light-emitting organs. Reflectors in the light organs of many shrimp, squid and fish are based on constructive interference systems but employ different biological materials. They and other structures modify the angular, spectral and intensity distributions of bioluminescent signals. The ready availability of highly efficient biological reflectors has been a formative influence in the evolution of bioluminescent signalling in the sea.

Flexible, angle-independent, structural color reflectors inspired by morpho butterfly wings.

Science.gov (United States)

Chung, Kyungjae; Yu, Sunkyu; Heo, Chul-Joon; Shim, Jae Won; Yang, Seung-Man; Han, Moon Gyu; Lee, Hong-Seok; Jin, Yongwan; Lee, Sang Yoon; Park, Namkyoo; Shin, Jung H

2012-05-08

Thin-film color reflectors inspired by Morpho butterflies are fabricated. Using a combination of directional deposition, silica microspheres with a wide size distribution, and a PDMS (polydimethylsiloxane) encasing, a large, flexible reflector is created that actually provides better angle-independent color characteristics than Morpho butterflies and which can even be bent and folded freely without losing its Morpho-mimetic photonic properties. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

A combination of transformation optics and surface impedance modulation to design compact retrodirective reflectors

Directory of Open Access Journals (Sweden)

H. Haddad

2018-02-01

Full Text Available This study proposes a new approach to flatten retrodirective corner reflectors. The proposed method enables compact reflectors via Transformation Optics (TO combined with Surface Impedance Modulation (SIM. This combination permits to relax the constraints on the anisotropic material resulting from the TO. Phase gradient approach is generalized to be used within anisotropic media and is implemented with SIM. Different reflector setups are designed, simulated and compared for fop = 8GHz using ANSYS® HFSS® in order to validate the use of such a combination.

A gradient estimate for solutions to parabolic equations with discontinuous coefficients

Directory of Open Access Journals (Sweden)

Jishan Fan

2013-04-01

Full Text Available Li-Vogelius and Li-Nirenberg gave a gradient estimate for solutions of strongly elliptic equations and systems of divergence forms with piecewise smooth coefficients, respectively. The discontinuities of the coefficients are assumed to be given by manifolds of codimension 1, which we called them emph{manifolds of discontinuities}. Their gradient estimate is independent of the distances between manifolds of discontinuities. In this paper, we gave a parabolic version of their results. That is, we gave a gradient estimate for parabolic equations of divergence forms with piecewise smooth coefficients. The coefficients are assumed to be independent of time and their discontinuities are likewise the previous elliptic equations. As an application of this estimate, we also gave a pointwise gradient estimate for the fundamental solution of a parabolic operator with piecewise smooth coefficients. Both gradient estimates are independent of the distances between manifolds of discontinuities.

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

Science.gov (United States)

Oladeinde, Mobolaji Humphrey; Akpobi, John Ajokpaoghene

2011-10-01

The hydrodynamic and magnetohydrodynamic (MHD) lubrication problem of infinitely wide inclined and parabolic slider bearings is solved numerically using the finite element method. The bearing configurations are discretized into three-node isoparametric quadratic elements. Stiffness integrals obtained from the weak form of the governing equations are solved using Gauss quadrature to obtain a finite number of stiffness matrices. The global system of equations obtained from enforcing nodal continuity of pressure for the bearings are solved using the Gauss-Seidel iterative scheme with a convergence criterion of 10-10. Numerical computations reveal that, when compared for similar profile and couple stress parameters, greater pressure builds up in a parabolic slider compared to an inclined slider, indicating a greater wedge effect in the parabolic slider. The parabolic slider bearing is also shown to develop a greater load capacity when lubricated with magnetic fluids. The superior performance of parabolic slider bearing is more pronounced at greater Hartmann numbers for identical bearing structural parameters. It is also shown that when load carrying capacity is the yardstick for comparison, the parabolic slider bearings are superior to the inclined bearings when lubricated with couple stress or magnetic lubricants.

The Relationship Between Vancomycin Trough Concentrations and AUC/MIC Ratios in Pediatric Patients: A Qualitative Systematic Review.

Science.gov (United States)

Tkachuk, Stacey; Collins, Kyle; Ensom, Mary H H

2018-04-01

In adults, the area under the concentration-time curve (AUC) divided by the minimum inhibitory concentration (MIC) is associated with better clinical and bacteriological response to vancomycin in patients with methicillin-resistant Staphylococcus aureus who achieve target AUC/MIC ≥ 400. This target is often extrapolated to pediatric patients despite the lack of similar evidence. The impracticalities of calculating the AUC in practice means vancomycin trough concentrations are used to predict the AUC/MIC. This review aimed to determine the relationship between vancomycin trough concentrations and AUC/MIC in pediatric patients. We searched the MEDLINE and Embase databases, the Cochrane Database of Systematic Reviews, and the Cochrane Central Register of Controlled Trials using the medical subject heading (MeSH) terms vancomycin and AUC and pediatric* or paediatric*. Articles were included if they were published in English and reported a relationship between vancomycin trough concentrations and AUC/MIC. Of 122 articles retrieved, 11 met the inclusion criteria. One trial reported a relationship between vancomycin trough concentrations, AUC/MIC, and clinical outcomes but was likely underpowered. Five studies found troughs 6-10 mg/l were sufficient to attain an AUC/MIC > 400 in most general hospitalized pediatric patients. One study in patients undergoing cardiothoracic surgery found a trough of 18.4 mg/l achieved an AUC/MIC > 400. Two oncology studies reported troughs ≥ 15 mg/l likely attained an AUC/MIC ≥ 400. In critical care patients: one study found a trough of 9 mg/l did not attain the AUC/MIC target; another found 7 mg/l corresponded to an AUC/MIC of 400. Potential vancomycin targets varied based on the population studied but, for general hospitalized pediatric patients, troughs of 6-10 mg/l are likely sufficient to achieve AUC/MIC ≥ 400. For MIC ≥ 2 mg/l, higher troughs are likely necessary to achieve an AUC/MIC ≥ 400. More

Assessment of irradiation effects on beryllium reflector and heavy water tank of JRR-3M

Energy Technology Data Exchange (ETDEWEB)

Murayama, Yoji; Kakehuda, Kazuhiro [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

1998-10-01

The JRR-3M, a swimming pool type research reactor with beryllium and heavy water reflectors, has been operated since 1990. Since the beryllium reflectors are close to fuel and receive high fast neutron fluence in a relatively short time, they may be subject to change their dimensions by swelling due mostly to entrapped helium gaseous. This may bend the reflectors to the outside and narrow gaps between the reflectors and the fuel elements. The gaps have been measured with an ultrasonic thickness gage in an annual inspection. The results in 1996 show that the maximum of expansion in the diametral directions was 0.6 mm against 1.6 mm of a managed value for replacement of the reflector. A heavy water tank of the JRR-3M is made of aluminum alloy A5052. Surveillance tests of the alloy have been conducted to evaluate irradiation effects of the heavy water tank. Five sets of specimens of the alloy have been irradiated in the beryllium reflectors where fast neutron flux is higher than that in the heavy water tank. In 1994, one set of specimens had been unloaded and carried out the post-irradiation tests. The results show that the heavy water tank preserved satisfactory mechanical properties. (author)

The concentration principle applied to spaceborne solar arrays. AGORA mission: Studies synthesis

Science.gov (United States)

Laget, R.

1986-01-01

Studies that led to selection of the distributed 25 kW SARA LOUVRE concept for the solar cell generator to be flown on the AGORA asteroid mission, and the major characteristics of such a spaceborne solar array are summarized. In the SARA LOUVRE concept, a parabolic cross section reflector concentrates incident light over the rear face of the identical, preceding reflector dish. The whole set of reflectors is pivotally commanded, thus compensating the effects of depointing. Geometric concentration factor is 10. End of life power level at 2.5 AU is 4.5 kW.

Multi-Beam Focal Plane Arrays with Digital Beamforming for High Precision Space-Borne Ocean Remote Sensing

DEFF Research Database (Denmark)

Iupikov, Oleg A.; Ivashina, Mariana V.; Skou, Niels

2018-01-01

alternative radiometer systems: a conical scanner with an off-set parabolic reflector, and stationary wide-scan torus reflector system; each operating at C, X and Ku bands. Numerical results predict excellent beam performance for both systems with as low as 0:14 % total received power over the land.......The present-day ocean remote sensing instruments that operate at low microwave frequencies are limited in spatial resolution and do not allow for monitoring of the coastal waters. This is due the difficulties of employing a large reflector antenna on a satellite platform, and generating high-quality...

Use of deep seismic shooting to study graben-like troughs. [Urals

Energy Technology Data Exchange (ETDEWEB)

Makalovskiy, V.V.; Silayev, V.A.

1983-01-01

In the Southeast Perm Oblast, in the zone of articulation of the Russian platform and the Cisural trough, in order to study the structure of the graben-like troughs together with deep drilling, well seismic exploration is used by the method of deep seismic shooting (DSS). The DSS method developed by the Kamskiy department of the VNIGNI consists of blasting in the well shaft and recording of the elastic fluctuations on the Earth's surface. The use of the DSS made it possible to pinpoint structural details of the graben-like trough, and to clarify that this is in essence a zone of fracturing, where the lowered blocks alternated with elevated, and to establish the location and amplitude of the tectonic disorders. High geological information content, low labor intensity and rapidity of obtaining the results make it possible to recommend the DSS together with prospecting and exploratory drilling to study complexly constructed objects in order to reduce the number of unproductive wells.

Evidence and mechanism of Hurricane Fran-Induced ocean cooling in the Charleston Trough

Science.gov (United States)

Xie, Lian; Pietrafesa, L. J.; Bohm, E.; Zhang, C.; Li, X.

Evidence of enhanced sea surface cooling during and following the passage of Hurricane Fran in September 1996 over an oceanic depression located on the ocean margin offshore of Charleston, South Carolina (referred to as the Charleston Trough), [Pietrafesa, 1983] is documented. Approximately 4C° of sea surface temperature (SST) reduction within the Charleston Trough following the passage of Hurricane Fran was estimated based on SST imagery from Advanced Very High Resolution Radiometer (AVHRR) on the NOAA-14 polar orbiting satellite. Simulations using a three-dimensional coastal ocean model indicate that the largest SST reduction occurred within the Charleston Trough. This SST reduction can be explained by oceanic mixing due to storm-induced internal inertia-gravity waves.