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Sample records for compound parabolic concentrating

  1. Thermodynamics and the segmented compound parabolic concentrator

    Science.gov (United States)

    Widyolar, Bennett; Jiang, Lun; Winston, Roland

    2017-04-01

    Compound parabolic concentrator (CPC) reflector profiles are complex and can be difficult to manufacture using traditional methods. Computer numeric control machines, however, can approximate complex profiles by bending a series of small flat segments. We investigate the relationship between the number of segments and the optical transmission of a CPC approximated by equal length segments whose start and end points lie along the CPC profile. We also investigate a separate method for generating CPC-like profiles by adjusting the angle of each segment to satisfy the edge-ray principle. Three variations of this method are examined where the edge-ray condition is taken from the start, mid, and end points of each segment. A flux efficiency (FE) to compare concentrators, which combines the concentration ratio and optical efficiency, is introduced and directly relates to the maximum achievable flux on the absorber. We demonstrate that the FE defined is another way to look at the compromises one makes for a geometric concentrator designed under real-world constraints.

  2. Compound parabolic concentrator with cavity for tubular absorbers

    Science.gov (United States)

    Winston, Roland

    1983-01-01

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

  3. Design philosophy and construction of a high concentration compound parabolic concentrator

    CSIR Research Space (South Africa)

    Roos, TH

    2010-09-01

    Full Text Available A compound parabolic concentrator (CPC) with a concentration ratio of 16:1 is under development at CSIR for volumetric receiver and solar fuels development. The ideal shape has been approximated by 6 and 12 facets in the longitudinal...

  4. Compound parabolic concentrator technology development to commercial solar detoxification applications

    Energy Technology Data Exchange (ETDEWEB)

    Blanco, J.; Malato, S.; Fernandez, P. [CIEMAT, Plataforma Solar de Almeria (ES)] (and others)

    1999-07-01

    An EC-DGXII BRITE-EURAM-III-financed project called Solar detoxification technology in the treatment of persistent non-biodegradable chlorinated industrial water contaminants' is described. The objectives are to develop a simple, efficient and commercially competitive solar water treatment technology based on compound parabolic collectors (CPC) enabling design and erection of turnkey installations. A European industrial consortium, SOLARDETOX, representing industry and research in Spain, Portugal, Germany and Italy has been created through this project. Some of the most up-to-date scientific and technological results are given, including the design of the first industrial European solar detoxification treatment plant, the main project deliverable. (author)

  5. A Concentrator Photovoltaic System Based on a Combination of Prism-Compound Parabolic Concentrators

    Directory of Open Access Journals (Sweden)

    Ngoc Hai Vu

    2016-08-01

    Full Text Available We present a cost-effective concentrating photovoltaic system composed of a prism and a compound parabolic concentrator (P-CPC. In this approach, the primary collector consists of a prism, a solid compound parabolic concentrator (CPC, and a slab waveguide. The prism, which is placed on the input aperture of CPC, directs the incoming sunlight beam to be parallel with the main axes of parabolic rims of CPC. Then, the sunlight is reflected at the parabolic rims and concentrated at the focal point of these parabolas. A slab waveguide is coupled at the output aperture of the CPC to collect focused sunlight beams and to guide them to the solar cell. The optical system was modeled and simulated with commercial ray tracing software (LightTools™. Simulation results show that the optical efficiency of a P-CPC can achieve up to 89%. when the concentration ratio of the P-CPC is fixed at 50. We also determine an optimal geometric structure of P-CPC based on simulation. Because of the simplicity of the P-CPC structure, a lower-cost mass production process is possible. A simulation based on optimal structure of P-CPC was performed and the results also shown that P-CPC has high angular tolerance for input sunlight. The high tolerance of the input angle of sunlight allows P-CPC solar concentrator utilize a single sun tracking system instead of a highly precise dual suntracking system as cost effective solution.

  6. Thermal analysis of a compound parabolic concentrator for refrigeration applications

    Energy Technology Data Exchange (ETDEWEB)

    Ortega, Naghelli; Best, Roberto [Centro de Investigacion en Energia, UNAM, Temixco, Morelos (Mexico)

    2000-07-01

    The refrigeration system designed at the Centro de Investigacion en Energia (CIE), Mexico is able to produce, in optimal conditions, one hundred kilograms per day of ice by means of solar energy. A continuous absorption ammonia-water refrigeration cycle is employed. In its actual state, heat supply to the system is provided through a bank of evacuated tube solar collectors. Their principal difficulties encountered in this system are the indirect heat losses due to the coupling of the falling film generator to the solar heating subsystem that requires a heat transfer gradient and higher collector operating temperatures. Also the high initial cost of the evacuated tube collectors is a barrier for an economical feasible system. Currently, new types of solar collectors are being considered, more efficient and reliable, with a potentially lower cost. This type of collectors known as Compound Parabolic Collectors (CPC) succeed in working at the required temperatures for absorption refrigeration systems. Therefore, a new system is suggested and it is proposed to use a CPC array, where heat losses by the indirect heating system are avoided. In this work a simple method was developed in order to establish the energy balances in a CPC, with a steel tubular receiver without an evacuated glass shell. The receptor's model considers a bidimensional system in stationary state and it supposes a continuous medium. Four nonlinear, simultaneous equations were obtained to predict heat exchange among various components in the system. These equations were utilized in a computer program to analyze the collector performance under various operating conditions. Consequently, the prediction of temperature distribution with respect to position permits to calculate length and arrangement of the CPC for a determined refrigeration application. [Spanish] El sistema de refrigeracion en el Centro de Investigacion en Energia (CIE) Mexico es capaz de producir en condiciones optimas 100

  7. Compound parabolic concentrator optical fiber tip for FRET-based fluorescent sensors

    DEFF Research Database (Denmark)

    Hassan, Hafeez Ul; Nielsen, Kristian; Aasmul, Soren

    2015-01-01

    The Compound Parabolic Concentrator (CPC) optical fiber tip shape has been proposed for intensity based fluorescent sensors working on the principle of FRET (Förster Resonance Energy Transfer). A simple numerical Zemax model has been used to optimize the CPC tip geometry for a step-index multimod...

  8. Coupled simulation of performance of a crossed compound parabolic concentrator with solar cell

    OpenAIRE

    2015-01-01

    An optimal installation of a compound parabolic concentrator (CCPC) into a scalable solar thermoelectrics and photovoltaics system is desirable by applying analytical tools to improve the optical and thermal performance of a CCPC with a solar cell. In this paper, the optical and thermal performances of an isolated CCPC with solar cell are investigated by employing commercial software ‘ANSYS CFX 15.0’ with a coupled optical grey and multiphysics model. Numerical results are validated against t...

  9. Polymer Optical Fiber Compound Parabolic Concentrator fiber tip based glucose sensor: In-Vitro Testing

    DEFF Research Database (Denmark)

    Hassan, Hafeez Ul; Janting, Jakob; Aasmul, Soren;

    2016-01-01

    We present in-vitro sensing of glucose using a newly developed efficient optical fiber glucose sensor based on a Compound Parabolic Concentrator (CPC) tipped polymer optical fiber (POF). A batch of 9 CPC tipped POF sensors with a 35 mm fiber length is shown to have an enhanced fluorescence pickup...... efficiency with an average increment factor of 1.7 as compared to standard POF sensors with a plane cut fiber tip. Invitro measurements for two glucose concentrations (40 and 400 mg/dL) confirm that the CPC tipped sensors efficiently can detect both glucose concentrations. it sets the footnote at the bottom...

  10. Tapering of Polymer Optical Fibers for Compound Parabolic Concentrator Fiber Tip Fabrication

    DEFF Research Database (Denmark)

    Hassan, Hafeez Ul; Fasano, Andrea; Nielsen, Kristian

    2015-01-01

    We propose a process for Polymer Optical Fiber (POF) Compound Parabolic Compound (CPC) tip manufacturing using a heat and pull fiber tapering technique. The POF, locally heated above its glass transition temperature, is parabolically tapered down in diameter, after which it is cut to the desired ...

  11. Optical and thermal performance of a three-dimensional compound parabolic concentrator for spherical absorber

    Indian Academy of Sciences (India)

    S Senthilkumar; K Perumal; P S S Srinivasan

    2009-06-01

    For medium range temperature applications, focusing type collectors like Compound Parabolic Concentrator (CPC) are most commonly used. Considerable research work has been carried out to improve the performance of the two-dimensional compound parabolic concentrator (2D CPC). The three-dimensional compound parabolic concentrator (3D CPC) was found to be more efficient than 2D CPC because of the higher concentration ratio. In the present work a 3D CPC was fabricated with a half acceptance angle of 4° for a spherical absorber of radius 100 mm. UV stabilized aluminized polyester foil having high reflectivity (0·85) was pasted on the reflector for a total height of 441 mm and an aperture width of 540 mm. The optical efficiency was estimated theoretically and compared with the experimental value. Experimentally determined values of optical and thermal efficiencies were in good agreement with theoretically predicted value. The experimental results shown that the optical efficiency obtained from the 3D CPC (0·626) was significantly higher than that of the 2D CPC (0·570) of similar dimensions. Since the optical efficiency of the 3D CPC was increased, the thermal efficiency of the collector was also increased. In addition to that, time constant of the concentrator was also calculated. The time constant of the 3D CPC (431 s) was fairly high when compared with the 2D CPC (110 s). An attempt was made to generate low pressure steam using 3D CPC in the in situ steam generation mode. The efficiency of the steam generation was about 38%, which was one of the possible applications of 3D CPC module.

  12. Femtosecond laser micromachining of compound parabolic concentrator fiber tipped glucose sensors

    DEFF Research Database (Denmark)

    Hassan, Hafeez Ul; Lacraz, Amédée; Kalli, Kyriacos

    2017-01-01

    in fluorescence pickup efficiency of a Förster resonance energy transfer-based POF glucose sensor. A Zemax model of the CPC-tipped sensor predicts an optimal improvement of a factor of 3.96 compared to the sensor with a plane-cut fiber tip. The fs laser micromachined CPC tip showed an increase of a factor of 3......We report on highly accurate femtosecond (fs) laser micromachining of a compound parabolic concentrator (CPC) fiber tip on a polymer optical fiber (POF). The accuracy is reflected in an unprecedented correspondence between the numerically predicted and experimentally found improvement...

  13. Compound parabolic concentrator design for red, green, blue, and white LED light mixing

    Science.gov (United States)

    Wei, An-Chi; Lo, Shih-Chieh; Hung, Pei-Fang; Lee, Ju-Yi; Yeh, Hong-Yih; Huang, Hong-Cheng; Li, Chia-Ming

    2016-08-01

    A light-mixing module consisting of a compound parabolic concentrator (CPC) and a fiber for mixing light from red, green, blue, and white (RGBW) LEDs was proposed. The design principle was investigated and a design prototype was demonstrated in a simulation. The simulated results showed that the chromatic nonuniformity was reduced to 1/10 when the fiber length was 40 times the core width, and the module efficiencies were more than 80% and more than 60% when the fiber lengths were 350 mm and 5 m, respectively. The proposed module is suitable for solar lighting compensation or indoor lighting, such as plant-factory lighting.

  14. Compound parabolic concentrator optical fiber tip for FRET-based fluorescent sensors

    DEFF Research Database (Denmark)

    Hassan, Hafeez Ul; Nielsen, Kristian; Aasmul, Soren;

    2015-01-01

    polymer optical fiber for an excitation and emission wavelength of 550 nm and 650nm, respectively. The model suggests an increase of a factor of 1.6 to 4 in the collected fluorescent power for an ideal CPC tip, as compared to the plane-cut fiber tip for fiber lengths between 5 and 45mm......The Compound Parabolic Concentrator (CPC) optical fiber tip shape has been proposed for intensity based fluorescent sensors working on the principle of FRET (Förster Resonance Energy Transfer). A simple numerical Zemax model has been used to optimize the CPC tip geometry for a step-index multimode...

  15. [Design of high-efficiency double compound parabolic concentrator system in near infrared noninvasive biochemical analysis].

    Science.gov (United States)

    Gao, Jing; Lu, Qi-Peng; Peng, Zhong-Qi; Ding, Hai-Quan; Gao, Hong-Zhi

    2013-05-01

    High signal-to-noise ratio (SNR) of system is necessary to obtain accurate blood components in near infrared noninvasive biochemical analysis. In order to improve SNR of analytical system, high-efficiency double compound parabolic concentrator (DCPC) system was researched, which was aimed at increasing light utilization efficiency. Firstly, with the request of collection efficiency in near infrared noninvasive biochemical analysis, the characteristic of emergent rays through compound parabolic concentrator (CPC) was analyzed. Then the maximum focusing angle range of the first stage CPC was determined. Secondly, the light utilization efficiency of truncated type was compared with standard DCPC, thus the best structure parameters of DCPC system were optimized. Lastly, combined with optical parameters of skin tissue, calculations were operated when incident wavelength is 1 000 nm. The light utilization efficiency of DCPC system, CPC-focusing mirror system, and non-optical collecting system was calculated. The results show that the light utilization efficiency of the three optical systems is 1.46%, 0.84% and 0.26% respectively. So DCPC system enhances collecting ability for human diffuse reflection light, and helps improve SNR of noninvasive biochemical analysis system and overall analysis accuracy effectively.

  16. Application of compound parabolic concentrators to solar photovoltaic conversion. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Cole, R.L.; Gorski, A.J.; Graven, R.M.; McIntire, W.R.; Schertz, W.W.; Winston, R.; Zwerdling, S.

    1977-02-01

    The final results of an analytical and experimental study of the application of nonimaging concentrators to solar photovoltaic conversion are presented. Two versions of the Compound Parabolic Concentrator (CPC) were considered, the Dielectric Compound Parabolic Concentrator (DCPC) in which the concentrator is filled with a dielectric material that satisfies requirements for Total Internal Reflection (TIR), and a conventional CPC in which metallic reflection is used for the mirror surfaces. Two working prototype panels were constructed and tested during the course of the program. The first was a 1.22 m by 1.22 m DCPC panel that requires only ten adjustments/year, has a panel utilization factor (packing factor) of 96%, and delivered the equivalent of 138 W (peak) under 1 kW/m/sup 2/ direct insolation. The net energy conversion efficiency was 10.3% over the entire panel area. The second panel was a conventional CPC panel measuring 1.22 m by 1.22 m. This panel requires thirty-six adjustments per year, and delivers the equivalent of 97 W when under 1 kW/m/sup 2/ direct insolation. The results of a cost-effectiveness analysis of the concept of using nonimaging concentrators for photovoltaic conversion are also presented. The concentrator panels showed a decided savings in comparison to the cost of flat plate photovoltaic panels, both at present-day silicon costs ($2000/m/sup 2/) and projected lower silicon costs ($200/m/sup 2/). At a silicon cost of $200/m/sup 2/, a two-dimensional (cone) version of the collector has the potential for achieving from $0.60-2.00 per average watt (about $0.15-0.50 per peak watt) while requiring only crude (+-4.5/sup 0/) tracking.

  17. Evaluation and optimization of the optical performance of low-concentrating dielectric compound parabolic concentrator using ray-tracing methods.

    Science.gov (United States)

    Sarmah, Nabin; Richards, Bryce S; Mallick, Tapas K

    2011-07-01

    We present a detailed design concept and optical performance evaluation of stationary dielectric asymmetric compound parabolic concentrators (DiACPCs) using ray-tracing methods. Three DiACPC designs, DiACPC-55, DiACPC-66, and DiACPC-77, of acceptance half-angles (0° and 55°), (0° and 66°), and (0° and 77°), respectively, are designed in order to optimize the concentrator for building façade photovoltaic applications in northern latitudes (>55 °N). The dielectric concentrator profiles have been realized via truncation of the complete compound parabolic concentrator profiles to achieve a geometric concentration ratio of 2.82. Ray-tracing simulation results show that all rays entering the designed concentrators within the acceptance half-angle range can be collected without escaping from the parabolic sides and aperture. The maximum optical efficiency of the designed concentrators is found to be 83%, which tends to decrease with the increase in incidence angle. The intensity is found to be distributed at the receiver (solar cell) area in an inhomogeneous pattern for a wide range of incident angles of direct solar irradiance with high-intensity peaks at certain points of the receiver. However, peaks become more intense for the irradiation incident close to the extreme acceptance angles, shifting the peaks to the edge of the receiver. Energy flux distribution at the receiver for diffuse radiation is found to be homogeneous within ±12% with an average intensity of 520 W/m².

  18. Polymer optical fiber compound parabolic concentrator tip for enhanced coupling efficiency for fluorescence based glucose sensors.

    Science.gov (United States)

    Hassan, Hafeez Ul; Nielsen, Kristian; Aasmul, Soren; Bang, Ole

    2015-12-01

    We demonstrate that the light excitation and capturing efficiency of fluorescence based fiber-optical sensors can be significantly increased by using a CPC (Compound Parabolic Concentrator) tip instead of the standard plane-cut tip. We use Zemax modelling to find the optimum CPC tip profile and fiber length of a polymer optical fiber diabetes sensor for continuous monitoring of glucose levels. We experimentally verify the improved performance of the CPC tipped sensor and the predicted production tolerances. Due to physical size requirements when the sensor has to be inserted into the body a non-optimal fiber length of 35 mm is chosen. For this length an average improvement in efficiency of a factor of 1.7 is experimentally demonstrated and critically compared to the predicted ideal factor of 3 in terms of parameters that should be improved through production optimization.

  19. Femtosecond laser micromachining of compound parabolic concentrator fiber tipped glucose sensors.

    Science.gov (United States)

    Hassan, Hafeez Ul; Lacraz, Amédée; Kalli, Kyriacos; Bang, Ole

    2017-03-01

    We report on highly accurate femtosecond (fs) laser micromachining of a compound parabolic concentrator (CPC) fiber tip on a polymer optical fiber (POF). The accuracy is reflected in an unprecedented correspondence between the numerically predicted and experimentally found improvement in fluorescence pickup efficiency of a Förster resonance energy transfer-based POF glucose sensor. A Zemax model of the CPC-tipped sensor predicts an optimal improvement of a factor of 3.96 compared to the sensor with a plane-cut fiber tip. The fs laser micromachined CPC tip showed an increase of a factor of 3.5, which is only 11.6% from the predicted value. Earlier state-of-the-art fabrication of the CPC-shaped tip by fiber tapering was of so poor quality that the actual improvement was 43% lower than the predicted improvement of the ideal CPC shape.

  20. Polymer optical fiber compound parabolic concentrator tip for enhanced coupling efficiency for fluorescence based glucose sensors

    Science.gov (United States)

    Hassan, Hafeez Ul; Nielsen, Kristian; Aasmul, Soren; Bang, Ole

    2015-01-01

    We demonstrate that the light excitation and capturing efficiency of fluorescence based fiber-optical sensors can be significantly increased by using a CPC (Compound Parabolic Concentrator) tip instead of the standard plane-cut tip. We use Zemax modelling to find the optimum CPC tip profile and fiber length of a polymer optical fiber diabetes sensor for continuous monitoring of glucose levels. We experimentally verify the improved performance of the CPC tipped sensor and the predicted production tolerances. Due to physical size requirements when the sensor has to be inserted into the body a non-optimal fiber length of 35 mm is chosen. For this length an average improvement in efficiency of a factor of 1.7 is experimentally demonstrated and critically compared to the predicted ideal factor of 3 in terms of parameters that should be improved through production optimization. PMID:26713213

  1. Polymer optical fiber compound parabolic concentrator tip for enhanced coupling efficiency for fluorescence based glucose sensors

    DEFF Research Database (Denmark)

    Hassan, Hafeez Ul; Nielsen, Kristian; Aasmul, Søren;

    2015-01-01

    We demonstrate that the light excitation and capturing efficiency of fluorescence based fiber-optical sensors can be significantly increased by using a CPC (Compound Parabolic Concentrator) tip instead of the standard plane-cut tip. We use Zemax modelling to find the optimum CPC tip profile...... and fiber length of a polymer optical fiber diabetes sensor for continuous monitoring of glucose levels. We experimentally verify the improved performance of the CPC tipped sensor and the predicted production tolerances. Due to physical size requirements when the sensor has to be inserted into the body...... a non-optimal fiber length of 35 mm is chosen. For this length an average improvement in efficiency of a factor of 1.7 is experimentally demonstrated and critically compared to the predicted ideal factor of 3 in terms of parameters that should be improved through production optimization....

  2. Secondary and compound concentrators for parabolic dish solar thermal power systems

    Science.gov (United States)

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

    1981-01-01

    A secondary optical element may be added to a parabolic dish solar concentrator to increase the geometric concentration ratio attainable at a given intercept factor. This secondary may be a Fresnel lens or a mirror, such as a compound elliptic concentrator or a hyperbolic trumpet. At a fixed intercept factor, higher overall geometric concentration may be obtainable with a long focal length primary and a suitable secondary matched to it. Use of a secondary to increase the geometric concentration ratio is more likely to e worthwhile if the receiver temperature is high and if errors in the primary are large. Folding the optical path with a secondary may reduce cost by locating the receiver and power conversion equipment closer to the ground and by eliminating the heavy structure needed to support this equipment at the primary focus. Promising folded-path configurations include the Ritchey-Chretien and perhaps some three element geometries. Folding the optical path may be most useful in systems that provide process heat.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1981-04-15

    A secondary optical element may be added to a parabolic dish solar concentrator to increase the geometric concentration ratio attainable at a given intercept factor. This secondary may be a Fresnel lens or a mirror, such as a compound elliptic concentrator or a hyperbolic trumpet. At a fixed intercept factor, higher overall geometric concentration may be obtainable with a long focal length primary and a suitable secondary matched to it. Use of a secondary to increase the geometric concentration ratio is more likely to be worthwhile if the receiver temperature is high and if errors in the primary are large. Folding the optical path with a secondary may reduce cost by locating the receiver and power conversion equipment closer to the ground and by eliminating the heavy structure needed to support this equipment at the primary focus. Promising folded-path configurations include the Ritchey-Chretien and perhaps some three-element geometries. Folding the optical path may be most useful in systems that provide process heat.

  4. Design and Optical Performance of Compound Parabolic Solar Concentrators with Evacuated Tube as Receivers

    Directory of Open Access Journals (Sweden)

    Qiang Wang

    2016-10-01

    Full Text Available In the present article, six symmetric compound parabolic solar concentrators (CPCs with all-glass evacuated solar tubes (EST as the receiver are designed, and a comparative study on their optical performance is performed based on theoretical analysis and ray-tracing simulations. In terms of optical loss through gaps of CPCs and optical efficiency averaged for radiation over the acceptance angle, CPC-6, designed based on a fictitious “hat”-shaped absorber with a “V” groove at the bottom, is the optimal design, and CPC-1, designed based on the cover tube, is the worst solution, whereas from the point of view of the annual collectible radiation on the EST, it is found that CPC-4, designed based on a fictitious “ice-cream” absorber, is the optimal design and CPC-1 is the worst solution. CPC-6, commonly regarded as the best design in the past, is not an optimal design in terms of annual collectible radiation after truncation. Results also indicate that, for high temperature applications, CPC-6 and CPC-4 are advisable due to the high solar flux on the EST resulting from the high optical efficiency for radiation within the acceptance angle.

  5. Performance Evaluation of a Solar Adsorption Refrigeration System with a Wing Type Compound Parabolic Concentrator

    Directory of Open Access Journals (Sweden)

    Muhammad Umair

    2014-03-01

    Full Text Available Simulation study of a solar adsorption refrigeration system using a wing type compound parabolic concentrator (CPC is presented. The system consists of the wing type collector set at optimum angles, adsorption bed, a condenser and a refrigerator. The wing type collector captures the solar energy efficiently in the morning and afternoon and provides the effective temperature for a longer period of time compared to that achieved by a linear collector. The objectives of the study were to evaluate the system behavior, the effect of wing length, and to compare the performance of the systems with wing type and linear CPCs. A detailed dynamic simulation model was developed based on mass and energy balance equations. The simulation results show that the system performance with wing type CPC increases by up to 6% in the summer and up to 2% in the winter, compared to the performance with a linear CPC having same collector length. The ice production also increases up to 13% in the summer with the wing type CPC. This shows that the wing type CPC is helpful to increase the performance of the system compared to the linear CPC with the same collector length and without the need for tracking.

  6. 3X compound parabolic concentrating (CPC) solar energy collector. Final technical report

    Energy Technology Data Exchange (ETDEWEB)

    Ballheim, R.W.

    1980-04-25

    Chamberlain engineers designed a 3X compound parabolic concentrating (CPC) collector for the subject contract. The collector is a completely housed, 105.75 x 44.75 x 10.23-inch, 240-pound unit with six each evacuated receiver assemblies, a center manifold and a one-piece glass cover. A truncated version of a CPC trough reflector system and the General Electric Company tubular evacuated receiver have been integrated with a mass producible collector design suitable for operation at 250 to 450/sup 0/F. The key criterion for optimization of the design was minimization of the cost per Btu collected annually at an operating temperature of 400/sup 0/F. The reflector is a 4.1X design truncated to a total height of 8.0 inches with a resulting actual concentration ratio of 2.6 to 1. The manifold is an insulated area housing the fluid lines which connect the six receivers in series with inlet and outlet tubes extending from one side of the collector at the center. The reflectors are polished, anodized aluminum which are shaped by the roll form process. The housing is painted, galvanized steel, and the cover glass is 3/16-inch thick tempered, low iron glass. The collector requires four slope adjustments per year for optimum effectiveness. Chamberlain produced ten 3X CPC collectors for the subject contract. Two collectors were used to evaluate assembly procedures, six were sent to the project officer in Albuquerque, New Mexico, one was sent to Argonne National Laboratory for performance testing and one remained with the Company. A manufacturing cost study was conducted to estimate limited mass production costs, explore cost reduction ideas and define tooling requirements. The final effort discussed shows the preliminary design for application of a 3X CPC solar collector system for use in the Iowa State Capitol complex.

  7. Optical receiving system based on a compound parabolic concentrator and a hemispherical lens for visible light communication.

    Science.gov (United States)

    Wang, Yun; Lan, Tian; Ni, Guoqiang

    2016-12-20

    We propose a scheme for designing a new optical receiving system that can reduce the received-energy spot size via integration of a compound parabolic concentrator with a hemispherical lens. SolidWorks is used to model the receiving system, while TracePro is employed for simulations. The field of view is set to 30° and the radius of the compound parabolic concentrator outlet is 5 mm, which is also the radius of the hemispherical lens. Ray-tracing results show that under the given simulation conditions, the radius of the spot area is reduced from 5 to 3 mm at the receiving system and the gain is 5.2. In regard to the relations between received power and the radius of the hemispherical lens R, and the received power and the distance d between the compound parabolic concentrator and hemispherical lens, our detailed analysis yields the following characteristics: (1) the received power increases as R increases, but decreases as d increases; (2) as R increases, the spot area increases and the received flux is dispersed over the receiving plane, which dispersion is disadvantageous for high-speed communication; (3) the gain of the receiving system also varies with R and d; (4) an increase in d leads to decrease in the received flux and gain when d>-2  mm. Based on these characteristics, we set R=5  mm and calculate the energy efficiency. We obtain maximum energy efficiencies for different detection areas.

  8. Numerical analysis on using compound parabolic couplers for direct transmission of concentrated solar radiation via optical fibre (Conference Presentation)

    Science.gov (United States)

    Rahou, Maryam; Andrews, John; Rosengarten, Gary

    2016-09-01

    A challenge in high-temperature solar thermal applications is transfer of concentrated solar radiation to the load with minimum energy loss. The use of a solar concentrator in conjunction with optical fibres has potential advantages in terms of transmission efficiency, technical feasibility and cost-effectiveness compared to a conventional heat transfer system employing heat exchangers and a heat transfer fluid. For transferring higher levels of concentrated flux it is necessary to employ multiple optical fibres or fibre bundles. However, the losses at the incident plane of a bundle due to absorption by the epoxy and cladding between the individual fibres in a bundle are substantial, typically over 60% of the overall transmission loss. The optical transmission of the system can thus be enhanced by employing a coupler between the concentrated solar radiation and the entrance to the bundle that reflects all incident light into the cores of individual fibres rather than allowing it to strike the interstitial spaces between the cores. This paper describes the design for such couplers based on multiple compound parabolic (CP) reflectors each with its exit aperture coinciding with the core of an individual fibre within the bundle. The proposed design employs external reflection from a machined metallic aluminium surface. This CP arrangement has the additional benefit of increasing the concentration ratio of the primary solar concentrator used. Simulation modeling using LightTools is conducted into a parabolic Cassegrain solar concentrator employing these CP couplers prior to a fibre bundle. The dependence of overall transmission and total optical efficiency of the system over lengths of the bundle up to 100 m are investigated quantitatively. In addition, the influence on transmission of the angular distribution of radiation intensity at the aperture of the couplers is studied.

  9. Phase 0: goal study for the technical and economic evaluation of the Compound Parabolic Concentrator (CPC) concept applied to solar thermal and photovoltaic collectors. Final report

    Energy Technology Data Exchange (ETDEWEB)

    None

    1975-06-01

    This report presents the results of a quick, six-week technical and economic evaluation of the compound parabolic concentrator (CPC) solar collector. The purpose of this effort was to provide an initial phase of a goals study that is directed toward recommending relative priorities for development of the compound parabolic concentrator concept. The findings of this study are of a very preliminary nature. Conclusions based on study findings at this depth should be considered preliminary and subject to revision and review in later phases.

  10. Low-concentration photovoltaic module with reflective compound parabolic concentrator fabricated by roll-to-roll slot-die coating and 3D printing.

    Science.gov (United States)

    Lee, Hyungman; Lim, Heonkwang; Park, Sungsik; Lee, Dongjin

    2016-12-26

    We fabricate a low-concentration photovoltaic (LCPV) module with a reflective compound parabolic concentrator (CPC) using roll-to-roll (R2R) slot-die coating and 3D printing technologies. A highly reflective silver thin-film is coated on a flexible plastic substrate, and the CPC frame is manufactured via 3D printing. The slot-die-coated silver film with thickness of more than 100 nm stably exhibits 95% reflectivity at 550 nm. Further, CPC concentrators with concentration ratios of 4X and 3X are assembled into silicon solar cells and characterized. Although the fill factor and maximum voltage slightly decrease, power and efficiency increase by factors of 3.51 and 2.63 with respect to the no-CPC-module case. Our approach can be used to optimize the design of various engineering products.

  11. Outdoor Performance Analysis of a Photovoltaic Thermal (PVT Collector with Jet Impingement and Compound Parabolic Concentrator (CPC

    Directory of Open Access Journals (Sweden)

    Ahed Hameed Jaaz

    2017-08-01

    Full Text Available This paper discusses the effect of jet impingement of water on a photovoltaic thermal (PVT collector and compound parabolic concentrators (CPC on electrical efficiency, thermal efficiency and power production of a PVT system. A prototype of a PVT solar water collector installed with a jet impingement and CPC has been designed, fabricated and experimentally investigated. The efficiency of the system can be improved by using jet impingement of water to decrease the temperature of the solar cells. The electrical efficiency and power output are directly correlated with the mass flow rate. The results show that electrical efficiency was improved by 7% when using CPC and jet impingement cooling in a PVT solar collector at 1:00 p.m. (solar irradiance of 1050 W/m2 and an ambient temperature of 33.5 °C. It can also be seen that the power output improved by 36% when using jet impingement cooling with CPC, and 20% without CPC in the photovoltaic (PV module at 1:30 p.m. The short-circuit current ISC of the PV module experienced an improvement of ~28% when using jet impingement cooling with CPC, and 11.7% without CPC. The output of the PV module was enhanced by 31% when using jet impingement cooling with CPC, and 16% without CPC.

  12. Outdoor Performance Analysis of a Photovoltaic Thermal (PVT) Collector with Jet Impingement and Compound Parabolic Concentrator (CPC)

    Science.gov (United States)

    Jaaz, Ahed Hameed; Hasan, Husam Abdulrasool; Sopian, Kamaruzzaman; Kadhum, Abdul Amir H.; Gaaz, Tayser Sumer

    2017-01-01

    This paper discusses the effect of jet impingement of water on a photovoltaic thermal (PVT) collector and compound parabolic concentrators (CPC) on electrical efficiency, thermal efficiency and power production of a PVT system. A prototype of a PVT solar water collector installed with a jet impingement and CPC has been designed, fabricated and experimentally investigated. The efficiency of the system can be improved by using jet impingement of water to decrease the temperature of the solar cells. The electrical efficiency and power output are directly correlated with the mass flow rate. The results show that electrical efficiency was improved by 7% when using CPC and jet impingement cooling in a PVT solar collector at 1:00 p.m. (solar irradiance of 1050 W/m2 and an ambient temperature of 33.5 °C). It can also be seen that the power output improved by 36% when using jet impingement cooling with CPC, and 20% without CPC in the photovoltaic (PV) module at 1:30 p.m. The short-circuit current ISC of the PV module experienced an improvement of ~28% when using jet impingement cooling with CPC, and 11.7% without CPC. The output of the PV module was enhanced by 31% when using jet impingement cooling with CPC, and 16% without CPC. PMID:28763048

  13. Outdoor Performance Analysis of a Photovoltaic Thermal (PVT) Collector with Jet Impingement and Compound Parabolic Concentrator (CPC).

    Science.gov (United States)

    Jaaz, Ahed Hameed; Hasan, Husam Abdulrasool; Sopian, Kamaruzzaman; Kadhum, Abdul Amir H; Gaaz, Tayser Sumer; Al-Amiery, Ahmed A

    2017-08-01

    This paper discusses the effect of jet impingement of water on a photovoltaic thermal (PVT) collector and compound parabolic concentrators (CPC) on electrical efficiency, thermal efficiency and power production of a PVT system. A prototype of a PVT solar water collector installed with a jet impingement and CPC has been designed, fabricated and experimentally investigated. The efficiency of the system can be improved by using jet impingement of water to decrease the temperature of the solar cells. The electrical efficiency and power output are directly correlated with the mass flow rate. The results show that electrical efficiency was improved by 7% when using CPC and jet impingement cooling in a PVT solar collector at 1:00 p.m. (solar irradiance of 1050 W/m² and an ambient temperature of 33.5 °C). It can also be seen that the power output improved by 36% when using jet impingement cooling with CPC, and 20% without CPC in the photovoltaic (PV) module at 1:30 p.m. The short-circuit current ISC of the PV module experienced an improvement of ~28% when using jet impingement cooling with CPC, and 11.7% without CPC. The output of the PV module was enhanced by 31% when using jet impingement cooling with CPC, and 16% without CPC.

  14. Secondary concentrators for parabolic dish solar thermal power systems

    Science.gov (United States)

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

    1981-01-01

    A variety of different concepts are currently being studied with the objective to lower the cost of parabolic mirrors and to provide alternatives. One of the considered approaches involves the use of compound concentrators. A compound solar concentrator is a concentrator in which the sunlight is reflected or refracted more than once. It consists of a primary mirror or lens, whose aperture determines the amount of sunlight gathered, and a smaller secondary mirror or lens. Additional small optical elements may also be incorporated. The possibilities and problems regarding a use of compound concentrators in parabolic dish systems are discussed. Attention is given to concentrating secondary lenses, secondary imaging and concentrating mirrors, conical secondary mirrors, compound elliptic secondary concentrating mirrors, and hyperbolic trumpet secondary concentrating mirrors.

  15. Design of a stacked diode array pumped Nd:YAG laser with a truncated compound parabolic concentrator and a diffusive optical cavity

    CERN Document Server

    Lee, S M; Yun, M J; Cha, B H; Lee, J M

    1999-01-01

    We designed and analyzed a new Nd:YAG laser which employs a combination of a truncated compound parabolic concentrator (CPC) and a diffusive optical pump cavity for pumping with a stacked diode array. A design code based on a ray-tracing algorithm was developed to analyze the Nd:YAG laser system. The optimum truncated CPC profile was determined from analyses of the dependences of the pump-beam distribution and the total absorbed power in the laser crystal upon the acceptance angle and the slit width of the CPC. In addition, the analyses show the importance of the acceptance angle in designing an efficient laser system with a truncated CPC. Using conservative design parameters, the design code predicted a Nd:YAG laser output of 130 W with a corresponding optical slope efficiency of 44%.

  16. Preliminary Ray Tracing and Experimental Study on the Effect of Mirror Coating on the Optical Efficiency of a Solid Dielectric Compound Parabolic Concentrator

    Directory of Open Access Journals (Sweden)

    Jie Ji

    2012-09-01

    Full Text Available This study aims to determine the necessity of applying a mirror coating on the side of a truncated solid dielectric CPC (compound parabolic concentrator since ray tracing analysis has revealed that part of the incoming rays do not undergo total internal reflection, even within the half acceptance angle of the CPC. An experiment was designed and conducted indoors and outdoors to study the effect of mirror coating on the optical performance of a solid dielectric CPC. Ray tracing was also employed for the detailed analysis and its results are compared with the measurements. Based on these, a concept of partial coating is proposed and verified through simulation. The results show that a partly coated solid dielectric CPC may have a better optical efficiency than a solid CPC without coating for a certain range of incidence angles.

  17. Construção e estudos de perfomance de um reator fotoquímico tipo CPC ("Compound Parabolic Concentrator"

    Directory of Open Access Journals (Sweden)

    Duarte Edward Thomas Fleury Mendonça

    2005-01-01

    Full Text Available A CPC (Compound Parabolic Concentrator reactor was projected and constructed aiming to promote the degradation of the organic matter present in considerable volumes of aqueous effluents, under the action of solar radiation. The essays were done using a model effluent which consists of a mixture of fragments of a sodium salt of lignosulphonic acid possessing a mean molecular weigth of 52,000 Daltons, and a real effluent, from a chip board industry. The volume of effluent in each test was about 50 L. The tests involved heterogeneous (TiO2 P25 Degussa and formulations made from the association of TiO2 with a photosensitiser, and homogeneous (thermal and photochemical Fenton reactions catalysis of the effluents. The results demonstrate the viability of application of this kind of reactor even when the load of organic pollutants is high.

  18. 紫外通信中复合抛物面聚光器的优化%Optimization for compound parabolic concentrator in UV communication

    Institute of Scientific and Technical Information of China (English)

    李晓明; 华文深; 马左红; 张悦

    2012-01-01

    为了提高紫外通信系统中接收机探测信号的灵敏度和效率,设计光学天线增强对大气中微弱信号的收集能力.结合紫外光通信系统的实际工程背景,对光探测中的复合抛物面聚光器(CPC)进行旋转、平移、截顶和截底4种优化,并做了详细的计算、模拟与仿真;通过对不同优化方法的最大入射角、接收光通量效率以及入射角与采集率关系的计算分析,得出不同参数优化后的工程适用条件,即负向旋转法可用于视线直射远距通信,截底法适用于非视线散射近距通信,而截顶法可用来替换标准CPC并达到节约材料成本的目的.%In order to enhance detectors' sensitivity and efficiency in UV communication system, an optical antenna was designed to strengthen the ability of collecting weak light signal in atmosphere. Based on the practical engineering background of UV optical communication system, a compound parabolic concentrator (CPC) for optical detection was optimized using rotation, translation, cutting of top and cutting of bottom respectively. Calculation, simulation and emulation of CPC were conducted. The parameters, such as maximum incident angle, flux efficiency and relationship between incident angle and the collection rate in different optimized methods for the compound parabolic concentrator for light detection were calculated and analyzed. Then different engineering conditions where different optimized methods worked were deduced. Namely, the negative direct rotation method can be used for line of sight distance communication. Cutting of bottom method can be served for the non-line-of-sight scattering short-range communications, and cutting of top CPC can be used to replace the standard one to save material cost.

  19. Symmetric Compound Parabolic Concentrator with Indium Tin Oxide Coated Glass as Passive Cooling System for Photovoltaic Application

    OpenAIRE

    Damasen Ikwaba Paul

    2016-01-01

    One problem with concentrating photovoltaic systems is the increase in operating photovoltaic module temperature which results in power output reduction. Indium Tin Oxide (ITO) coated glasses exhibit both high transmittance in the visible region and high reflectance in the infrared region of the solar spectrum. Such materials can be used as selective windows in photovoltaic modules operating under concentrating system enabling passive cooling. In this paper, a Heat Reflector Window (HRW) cons...

  20. 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.

  1. Speeding up the solar water disinfection process (SODIS) against Cryptosporidium parvum by using 2.5l static solar reactors fitted with compound parabolic concentrators (CPCs).

    Science.gov (United States)

    Gómez-Couso, H; Fontán-Sainz, M; Fernández-Ibáñez, P; Ares-Mazás, E

    2012-12-01

    Water samples of 0, 5, and 100 nephelometric turbidity units (NTU) spiked with Cryptosporidium parvum oocysts were exposed to natural sunlight in 2.5l static borosilicate solar reactors fitted with two different compound parabolic concentrators (CPCs), CPC1 and CPC1.89, with concentration factors of the solar radiation of 1 and 1.89, respectively. The global oocyst viability was calculated by the evaluation of the inclusion/exclusion of the fluorogenic vital dye propidium iodide and the spontaneous excystation. Thus, the initial global oocyst viability of the C. parvum isolate used was 95.3 ± 1.6%. Using the solar reactors fitted with CPC1, the global viability of oocysts after 12h of exposure was zero in the most turbid water samples (100 NTU) and almost zero in the other water samples (0.3 ± 0.0% for 0 NTU and 0.5 ± 0.2% for 5 NTU). Employing the solar reactors fitted with CPC1.89, after 10h exposure, the global oocyst viability was zero in the non-turbid water samples (0 NTU), and it was almost zero in the 5 NTU water samples after 8h of exposure (0.5 ± 0.5%). In the most turbid water samples (100 NTU), the global viability was 1.9 ± 0.6% after 10 and 12h of exposure. In conclusion, the use of these 2.5l static solar reactors fitted with CPCs significantly improved the efficacy of the SODIS technique as these systems shorten the exposure times to solar radiation, and also minimize the negative effects of turbidity. This technology therefore represents a good alternative method for improving the microbiological quality of household drinking water in developing countries. Copyright © 2012 Elsevier B.V. All rights reserved.

  2. Building a parabolic solar concentrator prototype

    Energy Technology Data Exchange (ETDEWEB)

    Escobar-Romero, J F M; Montiel, S Vazquez y; Granados-AgustIn, F; Rodriguez-Rivera, E; Martinez-Yanez, L [INAOE, Luis Enrique Erro 1, Tonantzintla, Pue., 72840 (Mexico); Cruz-Martinez, V M, E-mail: jfmescobar@yahoo.com [Universidad Tecnologica de la Mixteca, Camino a Acatilma Km 2.5, Huajuapan de Leon, Oax., 69000 (Mexico)

    2011-01-01

    In order to not further degrade the environment, people have been seeking to replace non-renewable natural resources such as fossil fuels by developing technologies that are based on renewable resources. An example of these technologies is solar energy. In this paper, we show the building and test of a solar parabolic concentrator as a prototype for the production of steam that can be coupled to a turbine to generate electricity or a steam engine in any particular industrial process.

  3. 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.

  4. Performance analysis of a novel trough compound parabolic concentrating photovoltaic collector%复合抛物面槽式光伏聚光器性能研究

    Institute of Scientific and Technical Information of China (English)

    于苗苗; 李承书; 侯静; 贾柠泽; 郑宏飞; 常泽辉

    2016-01-01

    文章提出了一种复合抛物面槽式光伏聚光器,介绍了该聚光器的工作原理,利用Solidworks软件对其进行三维建模,并通过光学仿真软件对不同入射偏角、光伏组件不同安装位置时接收体表面的光线接受率和聚光效率进行计算.该课题组搭建了复合抛物面槽式光伏聚光器试验台,对该光伏聚光器的输出电功率进行了测试和对比分析.结果表明:当复合抛物面槽式光伏聚光器径向入射偏角的变化范围为0~7°时,光线接受率为99.35%~60.49%;聚光效率随轴向入射偏角的增大呈线性降低的变化趋势;光线接受率和聚光效率随光伏组件与入射光之间夹角的增大而降低;在自然天气条件下,复合抛物面槽式光伏聚光器的输出电功率约为相同测试条件下平板光伏组件的2倍.%This paper presents a novel trough compound parabolic concentrating photovoltaic (CPV) collector.The performances of CPV have been studied via both optical calculation and experiment.A 3D model of the CPV supported with Solidworks software was used to analyze the raying tracing of the double-flat-plate solar cells.The distribution of the concentrated light can be visualized.The relationship between the optical efficiency of the CPV and the incident angle,installation position was investigated.In addition to theoretical analysis,a CPV collector was constructed,and experiments for CPV collector are carried out.The results indicate that the overall ray's receiving rate of 99.35%~60.49% are obtained with radial incidence angles of 0~7 °.The ray's receiving rate and optical efficiency decreases with the increase of the angle between cell and incident light.In the outdoors experiment,the output power of the CPV is about 2 times of the fiat-plate solar cell.

  5. Concentration phenomena in the semilinear parabolic equation

    Institute of Scientific and Technical Information of China (English)

    TAN; Zhong

    2001-01-01

    [1]Fujita, H., On the blowing up of solutions of the Chauch problem for u=Δu+u1+α, J. Fac. Sci. Univ. Tokyo Sect. I, 966, 3: 09.[2]Ni, W. -M., Sacks, P. E., Tavantzis, J., On the asymptotic behavior of solutions of certain quasilinear equations of parabolic type, J. Differential Equations, 984, 54: 97.[3]Cazenave, T., Lions, P. L., Solutions globales d'equations de la chaleur semilineaires, Comm. in Partial Differential Equations, 984, 9(0): 955.[4]Giga, Y., A bound for global solutions of semilinear heat equations, Commun. Math. Phys., 986, 03: 45.[5]Galaktionov, V., Vazquez, J. L., Continuation of blow-up solutions of nonlinear heat equations in several space dimensions, Comm. Pure Appl. Math., 997, 50: .[6]Rey, O., The role of the Green's function in a nonlinear elliptic equation involving the critical Sobolev exponent, J. Func. Anal., 990, 89: .[7]Wei Juncheng, Asymptotic behavior of least energy solution to a semilinear Dirichlet problem near the critical exponent, J. Math. Soc. Japan, 998, 50(): 39.[8]Lions, P. L., The concentration-compactness principle in the calculus of variations, The limit case ,2, Rev. Mat. Iberoamerioana, 985, : 45, 45.[9]Brezis, H., Elliptic equations with limiting Sobolev exponents——the impact of topology, Commun. Pure and Appl. Math., 986, XXXXIX: S7.[10]Sacks, J., Uhlenbeck, K., The existence of minimal immersions of 2-spheres, Ann. Math., 98, 3: .[11]Zhu Xiping, Nontrivial solutions of quasilinear elliptic equation involving critical growth, Science in China (in Chinese), Ser. A, 988, (3): 225.[12]Pohozaev, S. I., Eigenfunctions of the equation -Δu+λf(u)=0, Soviet. Math. Dold., 965, 6: 408.[13]Gidas, B., Ni, W. -M., Nirenberg, L., Symmetry and related properties via the maximum principle, Comm. Math. Phys., 979, 68: 209.[14]Ni, W. -M., Sacks, P. E., Singular behaviour in nonlinear parabolic equations, Tran. of the AMS, 985, 287(2): 657.[15]Ni, W. -M., Sacks, P. E

  6. Photocatalytic disinfection of water using low cost compound parabolic collectors

    Energy Technology Data Exchange (ETDEWEB)

    McLoughlin, O.A.; Gill, L.W. [Dublin Univ. (Ireland). Dept. of Civil, Structural and Environmental Engineering; Ibanez, F.; Gernjak, W.; Malato Rodriguez, S. [Plataforma Solar de Almeria (CIEMAT), Tabemas (Spain)

    2004-11-01

    The objective of this work was to assess the effectiveness of using near UV light to disinfect water supplies for potential applications in developing countries. A pilot scale photoreactor comprised of non-tracking compound parabolic collectors installed at Plataforma Solar de Almeria was examined and a comparison of disinfection efficiency using E. coli K-12 was carried out with a reactor configuration of 3 and 1 m{sup 2} illuminated area. Tests were also carried out using suspensions of titanium dioxide (TiO{sub 2}) at concentrations ranging from 0 to 9 mg/l. The removal of E. coli K-12 from initial concentrations of 1 x 10{sup 5} CFU/ml to below the limit of detection was achieved both with and without the use of TiO{sub 2}. Levels of inactivation in 35 l of inoculated water of up to 4-log removal were achieved in under 30 min. The addition of TiO{sub 2} created an enhancement to the process only at the 3 mg/l dose. However, the results have also suggested the possibility that another disinfection mechanism, possibly governed by the frequency of intermittent UV light exposure, was regulating the overall inactivation kinetics of the trials. (Author)

  7. Performance Simulation of Secondary Compound Parabolic Concentrator and Experimental Study on PV Generation%二级复合抛物面聚光器(CPC)性能仿真及光伏发电实验研究

    Institute of Scientific and Technical Information of China (English)

    唐亚平; 林海浩; 钟英杰

    2011-01-01

    The secondary compound parabolic concentrator (CPC) overlapped with two compound parabolic concentrators.In order to improve the integrative performance of secondary CPC, the paper analyzed the three key parameters which influence on CPC's performance, with orthogonal tests, variance analysis and level combination, and confirmed the optimizing constructive shape of secondary CPC. The 3-D model of secondary CPC was established with Pro/E and analysis of performance simulation was done with Tracepro software. The experimental tests for secondary CPC simulation set were carried out with xenon lamp as the light source. And results showed that concentrator effective concentrator ratio was about 2.5 and acceptance angle was about 25°, as structural shape of secondary CPC was 12°/35°-22°. Compared with non-concentrator photovoltaic power system, integral power value of PV generation composed of secondary CPC increased 246% on summer solstice, 252% both on spring equinox and autumnal equinox and 400% on winter solstice. [ Ch,6 fig. 2 tab. 11 ref. ]%构造出一个由2个复合抛物面聚光器(CPC)叠置组成的二级复合抛物面聚光器(CPC),为改善二级抛物面聚光器(CPC)的整体性能,对影响聚光器性能的3个关键参数,采用正交试验设计、方差分析和水平搭配的方法进行分析,并确定了二级CPC的优化结构形状.运用PRO-E建立二级CPC三维模型,并导入Tracepro软件进行性能仿真分析.用氙灯作为模拟太阳光源,对一组二级CPC模型装置进行了实验测试,仿真和实验的结果表明:二级CPC的结构形状为12°/35°~22°时,聚光器有效聚光比约为2.5,有效接收角为25°左右;由该聚光器构成的聚光光伏发电系统和太阳能非聚光光伏发电系统相比,功率积分值在夏至日提升了246%,春秋分提升了252%,冬至日提升了400%.

  8. Concentration phenomena in the semilinear parabolic equation

    Institute of Scientific and Technical Information of China (English)

    谭忠

    2001-01-01

    We prove the existence of the global, but unbounded solution of the semilinear heat equations with critical Sobolev exponent, and that under some assumptions, the global unbounded classical solution concentrates on origin as t→∞.

  9. Water disinfection by solar photocatalysis using compound parabolic collectors

    Energy Technology Data Exchange (ETDEWEB)

    Fernandez, P.; Blanco, J.; Sichel, C.; Malato, S. [Centro de Investigaciones Energeticas, Medioambientales y Tecnologicas (CIEMAT), Plataforma Solar de Almeria (PSA), P.O. Box 22, 04200 Tabernas, Almeria (Spain)

    2005-04-15

    TiO{sub 2} solar photocatalysis has been proven to be a degradation process for aqueous organic contaminant leading to total mineralisation of a large number of compounds. Furthermore, the interest in using this technique for water disinfection has grown in the last decade. Recent publications have reported photokilling of bacteria and viruses by TiO{sub 2} photocatalysis. Therefore, solar photocatalysis disinfection seems to be a very promising process, which could help to improve public health in rural areas of developing countries. The objective of this work was to assess the feasibility of using TiO{sub 2} solar photocatalysis to disinfect water supplies for future applications in developing countries. This article reviews the viability of solar photocatalysis for disinfection in low cost compound parabolic collectors, using sunlight and titanium dioxide semiconductor, both applied as slurry and supported. We report on the bactericidal action of TiO{sub 2} on a pure culture of Escherichia coli with a low cost photoreactor based on compound parabolic collectors. The influence of different experimental set-ups and parameters are also analysed. The results and potential application of the solar photocatalysis technology to water disinfection are studied within the frame of two research EU projects whose objective consist on the development of a fully autonomous solar reactor system to purify drinking water in remote locations of developing countries.

  10. 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.

  11. A solar distillery of essential oils with compound parabolic collectors (CPCs)

    OpenAIRE

    Kültürel, Yunus; Tarhan, Sefa

    2016-01-01

    A new essential oil distillation system was developed to produce the essential oils of medicinal and aromatic plants by water-steam distillation. This distillation system was composed of solar CPCs and distillation units. The solar CPCs unit comprised of seven solar compound parabolic collectors (CPCs), having 3.4 m² aperture area 1.9 concentration ratio. The distillation unit had a distillation tank, a condenser and an oil separator. The distillation unit was sized to distill 5 kg plant mate...

  12. Thermo-electronic solar power conversion with a parabolic concentrator

    Science.gov (United States)

    Olukunle, Olawole C.; De, Dilip K.

    2016-02-01

    We consider the energy dynamics of the power generation from the sun when the solar energy is concentrated on to the emitter of a thermo-electronic converter with the help of a parabolic mirror. We use the modified Richardson-Dushman equation. The emitter cross section is assumed to be exactly equal to the focused area at a height h from the base of the mirror to prevent loss of efficiency. We report the variation of output power with solar insolation, height h, reflectivity of the mirror, and anode temperature, initially assuming that there is no space charge effect. Our methodology allows us to predict the temperature at which the anode must be cooled in order to prevent loss of efficiency of power conversion. Novel ways of tackling the space charge problem have been discussed. The space charge effect is modeled through the introduction of a parameter f (0 solar insolation, height h, apart from radii R of the concentrator aperture and emitter, and the collector material properties. We have also considered solar thermos electronic power conversion by using single atom-layer graphene as an emitter.

  13. Mechanical design of a low cost parabolic solar dish concentrator

    Directory of Open Access Journals (Sweden)

    Hamza Hijazi

    2016-03-01

    Full Text Available The objective of this research was to design a low cost parabolic solar dish concentrator with small-to moderate size for direct electricity generation. Such model can be installed in rural areas which are not connected to governmental grid. Three diameters of the dish; 5, 10 and 20 m are investigated and the focal point to dish diameter ratio is set to be 0.3 in all studied cases. Special attention is given to the selection of the appropriate dimensions of the reflecting surfaces to be cut from the available sheets in the market aiming to reduce both cutting cost and sheets cost. The dimensions of the ribs and rings which support the reflecting surface are optimized in order to minimize the entire weight of the dish while providing the minimum possible total deflection and stresses in the beams. The study applies full stress analysis of the frame of the dish using Autodesk Inventor. The study recommends to use landscape orientation for the reflective facets and increase the ribs angle and the distance between the connecting rings. The methodology presented is robust and can be extended to larger dish diameters.

  14. Modeling of concentration polarization in a reverse osmosis channel with parabolic crossflow.

    Science.gov (United States)

    Liu, Cui; Morse, Audra; Rainwater, Ken; Song, Lianfa

    2014-01-01

    Concentration polarization in narrow reverse osmosis channels with parabolic crossflow was numerically simulated with finite different equations related to permeate velocity, crossflow velocity, average salt concentration, and wall salt concentration. A significant new theoretical development was the determination of two correction functions, F2 and F3, in the governing equation for average salt concentration. Simulations of concentration polarization under various conditions were then presented to describe the features of the new model as well as discussions about the differences of concentration polarizations of the more realistic parabolic flow with those when plug flow or shear flow was assumed. The situations in which the simpler models based on shear or plug flow can be used were indicated. Concentration polarization was also simulated for various conditions to show the applicability of the model and general features of concentration polarization in a narrow, long reverse osmosis channel.

  15. Reduction of effective terahertz focal spot size by means of nested concentric parabolic reflectors

    NARCIS (Netherlands)

    Neumann, V.A.; Laurita, N.J.; Pan, LiDong; Armitage, N.P.

    2016-01-01

    An ongoing limitation of terahertz spectroscopy is that the technique is generally limited to the study of relatively large samples of order 4 mm across due to the generally large size of the focal beam spot. We present a nested concentric parabolic reflector design which can reduce the terahertz fo

  16. Prism-coupled compound parabola: a new ideal and optimal solar concentrator.

    Science.gov (United States)

    Edmonds, I R

    1986-08-01

    A concentrator consisting of a compound parabola with foci at the apex of a prism is described. Design equations for the concentrator are derived, and it is shown that the concentrator is ideal and achieves the maximum theoretical concentration n/sin theta for specific values of prism apex angle and refractive index n of prism material. Truncation equations are given, and advantages of this concentrator relative to the compound parabolic concentrator are briefly discussed.

  17. THEORETICAL STUDY OF SOLAR COLLECTOR WITH MINI PARABOLIC CONCENTRATOR

    Directory of Open Access Journals (Sweden)

    I TABET

    2013-12-01

    Full Text Available In this paper, numerical modeling and simulation of the thermal behavior of a solar collector vacuum tube with a concentration has been done, the value of adding a system of concentration at the back of the collector and try to increase the amount of solar radiation incident on the collector  in order to obtain high temperatures compared to traditional flat plate collector  and improved their energy performance, this type of collector  being integrated into buildings for domestic hot water, air conditioning and for cooling.

  18. Low Power Thermodynamic Solar Energy Conversion: Coupling of a Parabolic Trough Concentrator and an Ericsson Engine

    Directory of Open Access Journals (Sweden)

    Pascal Stouffs

    2007-03-01

    Full Text Available This paper considers thermodynamic conversion of solar energy into electric energy (up to maximum 50 kWe, presenting a very brief review of the possible systems: the ‘Dish/Stirling’ technology, which relies on high temperature Stirling engines and requires high solar energy; low temperature differential thermal engine using direct solar energy without any concentration but with very low power per unit volume or unit mass of the system; and the intermediate solar energy concentration ratio.A theoretical investigation on the coupling of a two-stage parabolic trough concentrator with a reciprocating Joule cycle air engine (i.e. an Ericsson hot air engine in open cycle is presented. It is shown that there is an optimal operating point that maximises the mechanical power produced by the thermal engine. The interest of coupling a simple, low cost parabolic trough and a simple, low technology, mid-DT Ericsson engine is confirmed.

  19. Test results on parabolic dish concentrators for solar thermal power systems

    Science.gov (United States)

    Jaffe, Leonard D.

    1989-01-01

    This paper presents results of development testing of various solar thermal parabolic dish concentrators. The concentrators were mostly designed for the production of electric power using dish-mounted Rankine, Brayton or Stirling cycle engines, intended to be produced at low cost. Measured performance for various dishes included optical efficiencies ranging from 0.32 to 0.86 at a geometric concentration ratio of 500, and from about 0.09 to 0.85 at a geometric concentration ratio of 3000. Some malfunctions were observed. The tests should provide operating information of value in developing concentrators with improved performance and reduced maintenance.

  20. Test results on parabolic dish concentrators for solar thermal power systems

    Science.gov (United States)

    Jaffe, Leonard D.

    1989-01-01

    This paper presents results of development testing of various solar thermal parabolic dish concentrators. The concentrators were mostly designed for the production of electric power using dish-mounted Rankine, Brayton or Stirling cycle engines, intended to be produced at low cost. Measured performance for various dishes included optical efficiencies ranging from 0.32 to 0.86 at a geometric concentration ratio of 500, and from about 0.09 to 0.85 at a geometric concentration ratio of 3000. Some malfunctions were observed. The tests should provide operating information of value in developing concentrators with improved performance and reduced maintenance.

  1. Optimization of spherical facets for parabolic solar concentrators

    Science.gov (United States)

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

    1986-01-01

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

  2. Cost/performance of solar reflective surfaces for parabolic dish concentrators

    Science.gov (United States)

    Bouquet, F.

    1980-01-01

    Materials for highly reflective surfaces for use in parabolic dish solar concentrators are discussed. Some important factors concerning performance of the mirrors are summarized, and typical costs are treated briefly. Capital investment cost/performance ratios for various materials are computed specifically for the double curvature parabolic concentrators using a mathematical model. The results are given in terms of initial investment cost for reflective surfaces per thermal kilowatt delivered to the receiver cavity for various operating temperatures from 400 to 1400 C. Although second surface glass mirrors are emphasized, first surface, chemically brightened and anodized aluminum surfaces as well as second surface, metallized polymeric films are treated. Conventional glass mirrors have the lowest cost/performance ratios, followed closely by aluminum reflectors. Ranges in the data due to uncertainties in cost and mirror reflectance factors are given.

  3. Analysis of parabolic trough concentrator mirror shape accuracy in laboratory and collector

    OpenAIRE

    Meiser, Siw

    2014-01-01

    The present thesis examines the influence of measurement parameters and boundary conditions on shape accuracy of parabolic trough concentrator mirrors of RP3 geometry by means of optical measurements and finite element analyses. Deflectometric measurements of mirror panels are performed in common laboratory setups: in vertical and horizontal measurement position, both with and without tightening the mirrors to a support frame with screws. The results serve for validation of finite element mod...

  4. 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

  5. Parabolic single-crystal diamond compound refractive lenses for coherent x-ray imaging (Conference Presentation)

    Science.gov (United States)

    Terentyev, Sergey; Blank, Vladimir D.; Polyakov, Sergey; Zholudev, Sergey; Snigirev, Anatoly A.; Polikarpov, Maxim; Kolodziej, Tomasz; Qian, Jun; Zhou, Hua; Shvyd'ko, Yuri V.

    2016-09-01

    We demonstrate parabolic single-crystal diamond compound refractive lenses [1] designed for coherent x-ray imaging resilient to extreme thermal and radiation loading expected from next generation light sources. To ensure the preservation of coherence and resilience, the lenses are manufactured from the highest-quality single-crystalline synthetic diamond material grown by a high-pressure high-temperature technique. Picosecond laser milling is applied to machine lenses to parabolic shapes with a 1-micron precision and surface roughness. A compound refractive lens comprised of six lenses with a radius of curvature R=200 microns at the vertex of the parabola and a geometrical aperture A=900 microns focuses 10 keV x-ray photons from an undulator source at the Advanced Photon Source facility to a focal spot size of 10x40 microns^2 with a gain factor of 100. [1] S. Terentyev, V. Blank, S. Polyakov, S. Zholudev, A. Snigirev, M. Polikarpov, T. Kolodziej, J. Qian, H. Zhou, and Yu. Shvyd'ko Applied Physics Letters 107, 111108 (2015); doi: 10.1063/1.4931357

  6. Study of the Best Orientation for Parabolic Concentrator Kind of PolyTrough

    Directory of Open Access Journals (Sweden)

    Sharif Mohamed Alamen

    2014-10-01

    Full Text Available In this study, the best guide for Compound Parabolic Concentrator kind of (PolyTrough has been evaluated by controlling the angle of incidence of beam radiation. ThePolyTrough track the radiation of the sun by moving in prescribed ways to minimize the angle of incidence of the beam radiation on their surfaces and thus maximize the incident beam radiation. Tracking systems are classified according to their motions and rotations into five systems and they are: single axis, which is usually horizontal east-west and moving once (system I, continuously ( System II , horizontal north-south ( system III,IV moving continuously and parallel to the earth's axis respectively , or it can be about two axes (system V. We estimated the amount of direct solar radiation in each systemcontroller and then the comparison between the different control methods has been estimated. The results of the study have showed that the system V collects the largest amount of direct solar radiation, but the cost of this system is very expensive due to the presence of two types of collector's motion. While the fourth (IV system, is distinguished from the rest of the systems, because it collects a large amount of solar radiation in thewinter and decreases in the summer, where this system depends on the angle of the latitude of the site. The control system of the third kind (System III, which is less expensive than the type V and as it moves around one axis only, it collects the amount ofsolar energy approaching the system V especially in summer. The systems I and II collected values are close to each other, and although that these two systems collect a small amount of the solar radiation during the day comparing to the rest of the systems, this small amount of radiation is considered to be acceptable in the some studied areas.Keywords: PolyTrough, angle of incidence, direct solar radiation

  7. Slope Measurements of Parabolic Dish Concentrators Using Color-Coded Targets

    Energy Technology Data Exchange (ETDEWEB)

    Ulmer, S.; Heller, P.; Reinalter, W.

    2006-07-01

    A new short, yet highly accurate method for measuring the slope errors of parabolic dish concentrators has been developed. This method uses a flat target with colored stripes that is placed close to the focal plane and a digital camera located at an observation point on the optical axis at some distance from it. A specially developed image analysis algorithm detects the different colors in the images of the reflection of the target in the concentrator and assigns them their known position on the color target. This information, along with the geometric relationship between the components of the measurement setup and the theoretical parabolic shape of the concentrator, is used to calculate the normal vectors of the concentrator surface. From these normal vectors the radial and tangential slopes can be calculated and compared to the design values of the concentrator. The resulting slope errors not only give the total concentrator error for general characterization of the dish, but also indicate systematic errors in fabrication and mounting with high spatial resolution. In order to verify the quality of the results obtained, a ray-tracing code was developed that calculates the flux distribution on planes perpendicular to the optical axis. Measured slope errors of a DISTAL-2 dish concentrator are presented and the calculated flux distributions are compared to measured flux distributions. The comparison shows excellent agreement in the flux distribution on the absorber plane. This verifies the promising potential of this method for fast, highly precise measurement of imperfections in dish concentrator shape. (Author)

  8. 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.

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

    Science.gov (United States)

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

    2011-10-01

    A novel solar furnace system has been proposed to be consisted of a Nonimaging Focusing Heliostat and a smaller parabolic concentrator. In this configuration, the primary heliostat consists of 11×11 array of concave mirrors with a total reflective area of 121 m2 while the secondary parabolic concentrator has a focal length of 30 cm. To simplify the design and reduce the cost, fixed geometry of the primary heliostat is adopted to omit the requirement of continuous astigmatic correction throughout a year. The overall performance of the novel solar furnace configuration can be optimized if the heliostat's spinning-axis is fixed in the orientation dependent on the latitude angle so that the annual variation of incidence angle is the least, which ranges from 33° to 57°. Case study of the novel solar furnace system has been performed with the use of ray-tracing method to simulate solar flux distribution profile for two different target distances, i.e. 50 m and 100 m. The simulated results have revealed that the maximum solar concentration ratio ranges from 20,530 suns to 26,074 suns for the target distance of 50 m, and ranges from 40,366 suns to 43,297 suns for the target distance of 100 m.

  10. OPTICAL MODEL AND NUMERICAL SIMULATION OF THE NEW OFFSET TYPE PARABOLIC CONCENTRATOR WITH TWO TYPES OF SOLAR RECEIVERS

    Directory of Open Access Journals (Sweden)

    Saša Pavlović

    2015-08-01

    Full Text Available The paper presents a physical and mathematical model of the new offset type parabolic concentrator and a numerical procedure for predicting its optical performances. Also presented is the process of design and optical ray tracing analysis of a low cost solar concentrator for medium temperature applications. This study develops and applies a new mathematical model for estimating the intercept factor of the solar concentrator based on its geometrical and optical behavior. The solar concentrating system consists of three offset parabolic dish reflectors and a solar thermal absorber at the focus. Two types of absorbers are discussed. One is a flat plate circular absorber and the other a spiral smooth pipe absorber. The simulation results could serve as a useful reference for design and optimization of offset parabolic concentrators.

  11. Analysis of solar water heater with parabolic dish concentrator and conical absorber

    Science.gov (United States)

    Rajamohan, G.; Kumar, P.; Anwar, M.; Mohanraj, T.

    2017-06-01

    This research focuses on developing novel technique for a solar water heating system. The novel solar system comprises a parabolic dish concentrator, conical absorber and water heater. In this system, the conical absorber tube directly absorbs solar radiation from the sun and the parabolic dish concentrator reflects the solar radiations towards the conical absorber tube from all directions, therefore both radiations would significantly improve the thermal collector efficiency. The working fluid water is stored at the bottom of the absorber tubes. The absorber tubes get heated and increases the temperature of the working fluid inside of the absorber tube and causes the working fluid to partially evaporate. The partially vaporized working fluid moves in the upward direction due to buoyancy effect and enters the heat exchanger. When fresh water passes through the heat exchanger, temperature of the vapour decreases through heat exchange. This leads to condensation of the vapour and forms liquid phase. The working fluid returns to the bottom of the collector absorber tube by gravity. Hence, this will continue as a cyclic process inside the system. The proposed investigation shows an improvement of collector efficiency, enhanced heat transfer and a quality water heating system.

  12. 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.

  13. 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

  14. 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

    2015-12-04

    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.

  15. 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.

  16. 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.

  17. 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.

  18. Optical design and optimization of parabolic dish solar concentrator with a cavity hybrid receiver

    Science.gov (United States)

    Blázquez, R.; Carballo, J.; Silva, M.

    2016-05-01

    One of the main goals of the BIOSTIRLING-4SKA project, funded by the European Commission, is the development of a hybrid Dish-Stirling system based on a hybrid solar-gas receiver, which has been designed by the Swedish company Cleanergy. A ray tracing study, which is part of the design of this parabolic dish system, is presented in this paper. The study pursues the optimization of the concentrator and receiver cavity geometry according to the requirements of flux distribution on the receiver walls set by the designer of the hybrid receiver. The ray-tracing analysis has been performed with the open source software Tonatiuh, a ray-tracing tool specifically oriented to the modeling of solar concentrators.

  19. Study on the Optical Properties of Triangular Cavity Absorber for Parabolic Trough Solar Concentrator

    Directory of Open Access Journals (Sweden)

    Fei Chen

    2015-01-01

    Full Text Available A theoretical analytical method for optical properties of cavity absorber was proposed in this paper and the optical design software TracePro was used to analyze the optical properties of triangular cavity absorber. It was found that the optimal optical properties could be achieved with appropriate aperture width, depth-to-width ratio, and offset distance from focus of triangular cavity absorber. Based on the results of orthogonal experiment, the optimized triangular cavity absorber was designed. Results showed that the standard deviation of irradiance and optical efficiency of optimized designed cavity absorber were 30528 W/m2 and 89.23%, respectively. Therefore, this study could offer some valuable references for designing the parabolic trough solar concentrator in the future.

  20. Start-up performance of parabolic trough concentrating solar power plants

    DEFF Research Database (Denmark)

    Ferruzza, Davide; Topel, Monika; Basaran, Ibrahim

    2017-01-01

    Concentrating solar power plants, even though they can be integrated with thermal energy storage, are still subjected to cyclic start-up and shut-downs. As a consequence, in order to maximize their profitability and performance, the flexibility with respect to transient operations is essential....... In this regard, two of the key components identified are the steam generation system and steam turbine. In general it is desirable to have fast ramp-up rates during the start-up of a power plant. However ramp-up rates are limited by, among other things, thermal stresses, which if high enough can compromise...... generator to determine the optimal ramp rates. This paper presents a methodology to account for thermal stresses limitations during the power plant start up, aiming at identifying which components limit the ramp rates. A detailed dynamic model of a parabolic trough power plant was developed and integrated...

  1. Revisiting Parabolic Trough Concentrators for Industrial Process Heat in the United States

    Energy Technology Data Exchange (ETDEWEB)

    Turchi, Craig S.; Kurup, Parthiv; Zhu, Guangdong

    2016-06-03

    After significant interest in the 1970s, but relatively few deployments, the use of concentrating solar collectors for thermal applications, including enhanced oil recovery, desalination, and industrial process heat (IPH), is again increasing in global interest. In particular, recent advances in collector design and manufacturing have led to reduced cost per square meter of aperture area. In this study, analysis of a modern parabolic trough that is suited for use in small solar IPH (SIPH) applications predicts that the installed solar field cost can be as low as $170/m2. A slightly higher cost of $200/m2 is estimated for facilities typical of a SIPH plant size. Full project costs will include additional costs for contingency, piping and heat exchanger interface, and project indirect costs. The cost for solar-generated heat by SIPH is quantified by defining the levelized cost of heat (LCOH). California offers a favorable environment for SIPH given its good insolation, gas prices typically higher than the national average, and policies promoting solar-thermal deployment. Given historically low gas prices, competing with natural gas remains the primary challenge to deployment. However, this study finds that the solar LCOH for many regions in California is lower than the LCOH from natural gas, using a representative installed solar hardware price and the average price for industrial natural gas in California. Lastly, modification are in progress to the parabolic trough model within NREL's System Advisor Model (SAM) to allow users to more easily predict performance for these steam-generation applications.

  2. Charging studies of heat packs using parabolic dish solar energy concentrator for extreme conditions

    Science.gov (United States)

    Kumar, Rohitash; Vyas, Sumita; Kumar, Ravindra; Dixit, Ambesh

    2016-05-01

    Parabolic dish solar energy concentrator with aperture diameter 1.4 m and focal length 0.32 m is designed and fabricated to charge and store solar thermal energy in phase change material (PCM) based heat packs. Overall heat loss factor, heat duty, over all thermal efficiency, and optical efficiency factor are calculated using water sensible heating and cooling tests and values are 16.11 W m-2 K-1, 546.9 W, 49.2% and 0.62 respectively. The performance characteristic curve is generated using these parameters to understand its performance at different ambient temperatures and solar insolation. The fabricated concentrator has been used to charge 16 PCM heat packs with 150 g PCM in each heat pack, which took about 35 minutes for complete charging of PCM heat packs at average ambient temperature 39 °C and solar radiation flux density 715 W m-2 K-1. The charged heat packs are subjected to discharge studies at average ambient temperature about - 7 °C and observed heat release in the temperature range of 48 to 40 °C for 50 minutes, suggesting its applications for comfort and therapeutic applications in high altitude areas.

  3. Two new methods used to simulate the circumferential solar flux density concentrated on the absorber of a parabolic trough solar collector

    Science.gov (United States)

    Guo, Minghuan; Wang, Zhifeng; Sun, Feihu

    2016-05-01

    The optical efficiencies of a solar trough concentrator are important to the whole thermal performance of the solar collector, and the outer surface of the tube absorber is a key interface of energy flux. So it is necessary to simulate and analyze the concentrated solar flux density distributions on the tube absorber of a parabolic trough solar collector for various sun beam incident angles, with main optical errors considered. Since the solar trough concentrators are linear focusing, it is much of interest to investigate the solar flux density distribution on the cross-section profile of the tube absorber, rather than the flux density distribution along the focal line direction. Although a few integral approaches based on the "solar cone" concept were developed to compute the concentrated flux density for some simple trough concentrator geometries, all those integral approaches needed special integration routines, meanwhile, the optical parameters and geometrical properties of collectors also couldn't be changed conveniently. Flexible Monte Carlo ray trace (MCRT) methods are widely used to simulate the more accurate concentrated flux density distribution for compound parabolic solar trough concentrators, while generally they are quite time consuming. In this paper, we first mainly introduce a new backward ray tracing (BRT) method combined with the lumped effective solar cone, to simulate the cross-section flux density on the region of interest of the tube absorber. For BRT, bundles of rays are launched at absorber-surface points of interest, directly go through the glass cover of the absorber, strike on the uniformly sampled mirror segment centers in the close-related surface region of the parabolic reflector, and then direct to the effective solar cone around the incident sun beam direction after the virtual backward reflection. All the optical errors are convoluted into the effective solar cone. The brightness distribution of the effective solar cone is supposed

  4. Cytosolic Calcium Concentration Changes in Neuronal Cells Under Clinorotation and in Parabolic Flight Missions

    Science.gov (United States)

    Hauslage, Jens; Abbrecht, Medea; Hanke, Lars; Hemmersbach, Ruth; Koch, Claudia; Hanke, Wolfgang; Kohn, Florian P. M.

    2016-12-01

    All life on earth has been established under conditions of stable gravity of 1g. Nevertheless, in numerous experiments the direct gravity dependence of biological processes has been shown on all levels of organization, from single molecules to humans. To study the effects especially of microgravity on biological systems, a variety of platforms are available, from drop towers to the ISS. Due to the costs of these platforms and their limited availability, as an alternative, numerous simulators have been developed for so called "simulated" microgravity. A classical systems is a clinostat, basically rotating a sample around one axis, and by integration of the gravity vector for 360° arguing that thus the effects of gravity are depleted. Indeed, a variety of studies has shown that taking out the direction of gravity from a biological system often results in consequences similar to the exposure of the system to real microgravity. Nevertheless, the opposite has been shown, too, and as a consequence the relevance of clinostats in microgravity research is still under discussion. To get some more insight into this problem we have constructed a small fluorescence clinostat and have studied the effects of clinorotation on the cytosolic calcium concentration of neuroglioma cells. The results have been compared to experiments with identical cells in real microgravity, utilizing parabolic flight missions. Our results show that in case of a cell suspension used in a small florescence clinostat within a tube diameter of 2mm, the effects of clinorotation are comparable to those under real microgravity, both showing a significant increase in intracellular calcium concentration.

  5. Prediction and optimization of the performance of parabolic solar dish concentrator with sphere receiver using analytical function

    CERN Document Server

    Huang, Weidong; Hu, Peng; Chen, Zeshao

    2011-01-01

    Parabolic solar dish concentrator with sphere receiver is less studied. We present an analytic function to calculate the intercept factor of the system with real sun bright distribution and Gaussian distribution, the results indicate that the intercept factor is related to the rim angle of reflector and the ratio of open angle of receiver at the top of reflector to optical error when the optical error is larger than or equal to 5 mrad, but is related to the rim angle, open angle and optical error in less than 5 mrad optical error. Furthermore we propose a quick process to optimize the system to provide the maximum solar energy to net heat efficiency for different optical error under typical condition. The results indicate that the parabolic solar dish concentrator with sphere receiver has rather high solar energy to net heat efficiency which is 20% more than solar trough and tower system including higher cosine factor and lower heat loss of the receiver.

  6. Start-up performance of parabolic trough concentrating solar power plants

    Science.gov (United States)

    Ferruzza, Davide; Topel, Monika; Basaran, Ibrahim; Laumert, Björn; Haglind, Fredrik

    2017-06-01

    Concentrating solar power plants, even though they can be integrated with thermal energy storage, are still subjected to cyclic start-up and shut-downs. As a consequence, in order to maximize their profitability and performance, the flexibility with respect to transient operations is essential. In this regard, two of the key components identified are the steam generation system and steam turbine. In general it is desirable to have fast ramp-up rates during the start-up of a power plant. However ramp-up rates are limited by, among other things, thermal stresses, which if high enough can compromise the life of the components. Moreover, from an operability perspective it might not be optimal to have designs for the highest heating rates, as there may be other components limiting the power plant start-up. Therefore, it is important to look at the interaction between the steam turbine and steam generator to determine the optimal ramp rates. This paper presents a methodology to account for thermal stresses limitations during the power plant start up, aiming at identifying which components limit the ramp rates. A detailed dynamic model of a parabolic trough power plant was developed and integrated with a control strategy to account for the start-up limitations of both the turbine and steam generator. The models have been introduced in an existing techno-economic tool developed by the authors (DYESOPT). The results indicated that for each application, an optimal heating rates range can be identified. For the specific case presented in the paper, an optimal range of 7-10 K/min of evaporator heating rate can result in a 1.7-2.1% increase in electricity production compared to a slower component (4 K/min).

  7. A microscope for hard x-rays based on parabolic compound refractive lenses

    Science.gov (United States)

    Schroer, C. G.; Lengeler, B.; Benner, B.; Günzler, F.; Tümmler, J.; Drakopoulos, M.; Weitkamp, T.; Snigirev, A.; Snigireva, I.

    2000-05-01

    We describe refractive x-ray lenses with parabolic profile that are genuine imaging devices, similar to glass lenses for visible light. They open considerable possibilities in x-ray microscopy, tomography, microanalysis, and coherent scattering. Based on these lenses a microscope for hard x-rays is described, that can operate in the range from 2 to 60 keV, allowing for magnifications up to 50. At present, using aluminum lenses, it is possible to image an area of about 300μm in diameter with a resolving power of 0.3μm. Using beryllium as a lens material, the resolution can be increased below 0.1μm. The microscope allows to image opaque samples without destructive sample preparation and without the need of a vacuum chamber. It is particularly useful for in situ studies of wet samples, like biological and geological specimens. Imaging in both absorption and phase contrast is possible.

  8. Available Energy and Cumulative Frequency Curves for Parabolic Trough Concentrators with Alignment North–South, in the Northwest of Mexico

    Directory of Open Access Journals (Sweden)

    Álvaro Lentz–Herrea

    2009-04-01

    Full Text Available The Northwest of Mexico is a well known region with the highest ambient temperatures along the summer and the highest levels of irradiance, which make it feasible to install solar field concentrators. This work provides beam irradiance data that can be used to design a solar north–south parabolic trough system. The variation between the value of beam solar irradiance estimated by a pyranometer and the direct irradiance received by the aperture area of a parabolic trough concentrator (PTC is well–known as cosθ. This variation was evaluated every day of the year, obtaining values of average irradiance for Cerro Prieto (CP lat. 32°39', long. 115° 21', and San Luis Rio Colorado (SLR lat. 32°30', long. 114°46', with which they were elaborated the available energy and cumulative frequency curves (CFC. These are useful to know the number of hours of field solar concentrators which can operate at different levels of energy, as well as the steam production of a solar–geothermal hybrid system to produce electricity.

  9. Optical analysis of parabolic dish concentrators for solar dynamic power systems in space

    Science.gov (United States)

    Jefferies, K. S.

    1985-01-01

    An optical analysis of a parabolic solar collection system operating in Earth orbit was performed using ray tracing techniques. The analysis included the effects of: (1) solar limb darkening, (2) parametric variation of mirror surface error, (3) parametric variation of mirror rim angle, and (4) parametric variation of alignment and pointing error. This ray tracing technique used numerical integration to combine the effects of rays emanating from different parts of the sun at different intensities with the effects of normally distributed mirror-surface errors to compute the angular intensity distribution of rays leaving the mirror surface. A second numerical integration was then performed over the surface of the parabolic mirror to compute the radial distribution of brightness at the mirror focus. Major results of the analysis included: (1) solar energy can be collected at high temperatures with high efficiency, (2) higher absorber temperatures can be achieved at lower efficiencies, or higher efficiencies can be achieved at lower temperatures, and (3) collection efficiency is near its maximum level across a broad plateau of rim angles from 40 deg to 70 deg.

  10. Mass concentration and aging in the parabolic Anderson model with doubly-exponential tails

    OpenAIRE

    Biskup, Marek; Koenig, Wolfgang; Santos, Renato Soares dos

    2016-01-01

    We study the solutions $u=u(x,t)$ to the Cauchy problem on $\\mathbb Z^d\\times(0,\\infty)$ for the parabolic equation $\\partial_t u=\\Delta u+\\xi u$ with initial data $u(x,0)=1_{\\{0\\}}(x)$. Here $\\Delta$ is the discrete Laplacian on $\\mathbb Z^d$ and $\\xi=(\\xi(z))_{z\\in\\mathbb Z^d}$ is an i.i.d.\\ random field with doubly-exponential upper tails. We prove that, for large $t$ and with large probability, a majority of the total mass $U(t):=\\sum_x u(x,t)$ of the solution resides in a bounded neighbo...

  11. 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.

  12. SOLAR CONCENTRATORS' DEVELOPMENTS IN NIGERIA: A REVIEW.

    OpenAIRE

    Abdulrahim A.T; Diso I.S; EL-Jummah A. M

    2010-01-01

    The use of concentrators in the forms of solar energy collectors in order to concentrate sunrays for better usage is on the increase worldwide. To this effect, different types of solar concentrators have being developed over the years for various applications. The present study reviewed the various solar concentrators developed in Nigeria such as the parabolic fresnel concentrator, paraboloid solar cooker, parabolic trough collector, conical concentrator, compound parabolic solar concentrator...

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

    Science.gov (United States)

    Clark, J. A.

    1982-09-01

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

  14. Cost-effective solar furnace system using fixed geometry Non-Imaging Focusing Heliostat and secondary parabolic concentrator

    Energy Technology Data Exchange (ETDEWEB)

    Chong, K.K.; Lim, C.Y.; Hiew, C.W. [Faculty of Engineering and Science, Universiti Tunku Abdul Rahman, Off Jalan Genting Kelang, Setapak, Kuala Lumpur 53300 (Malaysia)

    2011-05-15

    A novel cost-effective solar furnace system is proposed to be consisted of a Non-Imaging Focusing Heliostat (NIFH) and a much smaller parabolic concentrator. In order to simplify the design and hence leading to the cost reduction, a fixed geometry of the NIFH heliostat is adopted in the novel solar furnace system by omitting the requirement of continuous astigmatic correction throughout the year with the use of local controllers. The performance of this novel solar furnace configuration can be optimized when the heliostat's spinning-axis is orientated in such a way that the annual variations of incident angle and therefore the annual variations of aberrant image size are the least. To verify the new configuration, a prototype solar furnace has been constructed at Universiti Tunku Abdul Rahman. (author)

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

    Science.gov (United States)

    Kaddour, A.; Benyoucef, B.

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

  16. Optical Efficiency of Low-Concentrating Solar Energy Systems with Parabolic Reflectors

    OpenAIRE

    Brogren, Maria

    2004-01-01

    Solar electricity is a promising energy technology for the future, and by using reflectors for concentrating solar radiation onto photovoltaic cells, the cost per produced kWh can be significantly reduced. The optical efficiency of a concentrating system determines the fraction of the incident energy that is transferred to the cells and depends on the optical properties of the system components. In this thesis, low-concentrating photovoltaic and photovoltaic-thermal systems with two-dimension...

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

    Science.gov (United States)

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

    2011-03-15

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2011-09-01

    Climate change and water scarcity are important issues for today's power sector. To inform capacity expansion decisions, hybrid life cycle assessment is used to evaluate a reference design of a parabolic trough concentrating solar power (CSP) facility located in Daggett, California, along four sustainability metrics: life cycle greenhouse gas (GHG) emissions, water consumption, cumulative energy demand (CED), and energy payback time (EPBT). This wet-cooled, 103 MW plant utilizes mined nitrate salts in its two-tank, thermal energy storage (TES) system. Design alternatives of dry-cooling, a thermocline TES, and synthetically-derived nitrate salt are evaluated. During its life cycle, the reference CSP plant is estimated to emit 26 g CO2eq per kWh, consume 4.7 L/kWh of water, and demand 0.40 MJeq/kWh of energy, resulting in an EPBT of approximately 1 year. The dry-cooled alternative is estimated to reduce life cycle water consumption by 77% but increase life cycle GHG emissions and CED by 8%. Synthetic nitrate salts may increase life cycle GHG emissions by 52% compared to mined. Switching from two-tank to thermocline TES configuration reduces life cycle GHG emissions, most significantly for plants using synthetically-derived nitrate salts. CSP can significantly reduce GHG emissions compared to fossil-fueled generation; however, dry-cooling may be required in many locations to minimize water consumption.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1993-09-01

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

  20. Performance Efficiency Improvement of Parabolic Solar Concentrating Collector (An Experimental Evaluation and Analysis

    Directory of Open Access Journals (Sweden)

    Durai Kalyana Kumar

    2014-12-01

    Full Text Available Energy conserved is energy generated’. Energy crisis is one of the crucial problems faced by all countries due to the rapid depletion of natural resources. A viable and an immediate solution at this juncture is the use of renewable energy sources like solar energy, wind energy, etc. A focusing type solar energy concentrator was fabricated and tested to evaluate its performance and to improve its operation efficiency. The experimental evaluations were carried out during the solar window (between 9:00 am to 3:00 pm using the statistical solar irradiation data and the real time measurements carried out using a pyranometer. Efficiency improvement was tried through different reflecting surfaces, greenhouse effect and selective coating. The energy conservation, preservation of fossil fuel and carbon foot print were estimated along with the cost economics and presented in this article in a very simplified style.

  1. 槽式太阳能集热器聚光传热特性浅析%Brief Analysis of Concentrating Characteristic of Parabolic Trough Collector

    Institute of Scientific and Technical Information of China (English)

    韦彪

    2016-01-01

    以槽式太阳能集热器为研究对象,基于槽式真空集热器光学理论,使用SolTrace建立集热器模型,并运用射线追踪法进行了辐射计算及分析,获取了吸热管吸热面热流的分布特性.研究结果为进一步研究槽式真空吸热管传热特性提供了理论依据.%Based on optical properties of parabolic trough solar collector,models of collector were established to research the concentrated flux density distribution by SolTrace.Results of calculation provide a theoretical foundation for further research on heat transfer characteristics in the receiver tubes of parabolic trough solar collectors.

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

    Science.gov (United States)

    1981-01-01

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

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

    Science.gov (United States)

    Fontán-Sainz, María; Gómez-Couso, Hipólito; Fernández-Ibáñez, Pilar; Ares-Mazás, Elvira

    2012-01-01

    Water samples of 0, 5, and 30 nephelometric turbidity units (NTU) spiked with Cryptosporidium parvum oocysts were exposed to natural sunlight using a 25-L static solar reactor fitted with a compound parabolic collector (CPC). The global oocyst viability was calculated by the evaluation of the inclusion/exclusion of the fluorogenic vital dye propidium iodide and the spontaneous excystation. After an exposure time of 8 hours, the global oocyst viabilities were 21.8 ± 3.1%, 31.3 ± 12.9%, and 45.0 ± 10.0% for turbidity levels of 0, 5, and 30 NTU, respectively, and these values were significantly lower (P 10 times). PMID:22302852

  4. Serum vaccine antibody concentrations in children exposed to perfluorinated compounds

    DEFF Research Database (Denmark)

    Grandjean, Philippe; Andersen, Elisabeth Wreford; Budtz-Jørgensen, Esben

    2012-01-01

    Perfluorinated compounds (PFCs) have emerged as important food contaminants. They cause immune suppression in a rodent model at serum concentrations similar to those occurring in the US population, but adverse health effects of PFC exposure are poorly understood....

  5. Modeling the Photocatalytic Mineralization in Water of Commercial Formulation of Estrogens 17-β Estradiol (E2 and Nomegestrol Acetate in Contraceptive Pills in a Solar Powered Compound Parabolic Collector

    Directory of Open Access Journals (Sweden)

    José Colina-Márquez

    2015-07-01

    Full Text Available Endocrine disruptors in water are contaminants of emerging concern due to the potential risks they pose to the environment and to the aquatic ecosystems. In this study, a solar photocatalytic treatment process in a pilot-scale compound parabolic collector (CPC was used to remove commercial estradiol formulations (17-β estradiol and nomegestrol acetate from water. Photolysis alone degraded up to 50% of estradiol and removed 11% of the total organic carbon (TOC. In contrast, solar photocatalysis degraded up to 57% of estrogens and the TOC removal was 31%, with 0.6 g/L of catalyst load (TiO2 Aeroxide P-25 and 213.6 ppm of TOC as initial concentration of the commercial estradiols formulation. The adsorption of estrogens over the catalyst was insignificant and was modeled by the Langmuir isotherm. The TOC removal via photocatalysis in the photoreactor was modeled considering the reactor fluid-dynamics, the radiation field, the estrogens mass balance, and a modified Langmuir–Hinshelwood rate law, that was expressed in terms of the rate of photon adsorption. The optimum removal of the estrogens and TOC was achieved at a catalyst concentration of 0.4 g/L in 29 mm diameter tubular CPC reactors which approached the optimum catalyst concentration and optical thickness determined from the modeling of the absorption of solar radiation in the CPC, by the six-flux absorption-scattering model (SFM.

  6. Modeling the photocatalytic mineralization in water of commercial formulation of estrogens 17-β estradiol (E2) and nomegestrol acetate in contraceptive pills in a solar powered compound parabolic collector.

    Science.gov (United States)

    Colina-Márquez, José; Machuca-Martínez, Fiderman; Li Puma, Gianluca

    2015-07-22

    Endocrine disruptors in water are contaminants of emerging concern due to the potential risks they pose to the environment and to the aquatic ecosystems. In this study, a solar photocatalytic treatment process in a pilot-scale compound parabolic collector (CPC) was used to remove commercial estradiol formulations (17-β estradiol and nomegestrol acetate) from water. Photolysis alone degraded up to 50% of estradiol and removed 11% of the total organic carbon (TOC). In contrast, solar photocatalysis degraded up to 57% of estrogens and the TOC removal was 31%, with 0.6 g/L of catalyst load (TiO2 Aeroxide P-25) and 213.6 ppm of TOC as initial concentration of the commercial estradiols formulation. The adsorption of estrogens over the catalyst was insignificant and was modeled by the Langmuir isotherm. The TOC removal via photocatalysis in the photoreactor was modeled considering the reactor fluid-dynamics, the radiation field, the estrogens mass balance, and a modified Langmuir-Hinshelwood rate law, that was expressed in terms of the rate of photon adsorption. The optimum removal of the estrogens and TOC was achieved at a catalyst concentration of 0.4 g/L in 29 mm diameter tubular CPC reactors which approached the optimum catalyst concentration and optical thickness determined from the modeling of the absorption of solar radiation in the CPC, by the six-flux absorption-scattering model (SFM).

  7. 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.

  8. Solar energy concentrator design and operation. Citations from the NTIS data base

    Science.gov (United States)

    Hundemann, A. S.

    1980-09-01

    Government funded research on the design and operation of various types of solar energy concentrators is discussed. Abstracts cover the efficiency and optimization of Fresnel lenses, V-through concentrators, flat plate and parabolic reflectors, compound parabolic concentrators used in solar photovoltaic conversion and heliostat systems. A few abstracts deal with heat loss and cost studies.

  9. Serum Vaccine Antibody Concentrations in Children Exposed to Perfluorinated Compounds

    DEFF Research Database (Denmark)

    Grandjean, P.; Andersen, E. W.; Budtz-Jorgensen, E.

    2012-01-01

    in follow-up through 2008. Main Outcome Measures Serum antibody concentrations against tetanus and diphtheria toxoids at ages 5 and 7 years. Results Similar to results of prior studies in the United States, the PFCs with the highest serum concentrations were perfluorooctane sulfonic acid (PFOS......Context Perfluorinated compounds (PFCs) have emerged as important food contaminants. They cause immune suppression in a rodent model at serum concentrations similar to those occurring in the US population, but adverse health effects of PFC exposure are poorly understood. Objective To determine......) and perfluorooctanoic acid (PFOA). Among PFCs in maternal pregnancy serum, PFOS showed the strongest negative correlations with antibody concentrations at age 5 years, for which a 2-fold greater concentration of exposure was associated with a difference of -39% (95% CI, -55% to -17%) in the diphtheria antibody...

  10. Parabolic-like maps

    CERN Document Server

    Lomonaco, Luciana Luna Anna

    2011-01-01

    In this paper we introduce the notion of parabolic-like mapping, which is an object similar to a polynomial-like mapping, but with a parabolic external class, i.e. an external map with a parabolic fixed point. We prove a straightening theorem for parabolic-like maps, which states that any parabolic-like map of degree 2 is hybrid conjugate to a member of the family Per_1(1), and this member is unique (up to holomorphic conjugacy) if the filled Julia set of the parabolic-like map is connected.

  11. Comparison of organochlorine compound concentrations in colostrum and mature milk.

    Science.gov (United States)

    Yu, Zhiwei; Palkovicova, Lubica; Drobna, Beata; Petrik, Jan; Kocan, Anton; Trnovec, Tomas; Hertz-Picciotto, Irva

    2007-01-01

    Human breast milk represents the best choice for the nutrition of infants. It is often used for monitoring human exposures to environmental chemicals. Uniquely suited to meet human biological needs, breast milk composition, especially fat content, changes significantly with time from delivery. With the aim to compare the concentration of organochlorine compounds (OCs) in colostrum versus mature milk, we obtained samples of fourth-fifth day postpartum milk (colostrum) and day-14 postpartum milk (mature milk) from 12 women enrolled in the project "Early Childhood Development and PCB Exposure in Slovakia". The concentrations of selected organochlorine pesticides and congeners of polychlorinated biphenyls (PCBs) were measured using gas chromatography with electron capture detection and reported on lipid adjusted basis. No significant differences were found between organochlorine levels in colostrum and those in mature milk samples. A very close correlation was found between the concentrations of organochlorine compounds in colostrum and mature milk (Spearman correlation coefficient r=0.94-0.98 for PCBs, and r=0.85-0.99 for organochlorine pesticides, p<0.001 for all compounds). The present study concludes that the use of colostrum samples provides a close estimate of the child's exposure to OCs in the early neonatal period and demonstrates that, despite the lower fat content, colostrum specimens are adequate to conduct OC analyses.

  12. Investigation of spherical and concentric mechanism of compound droplets

    Directory of Open Access Journals (Sweden)

    Meifang Liu

    2016-07-01

    Full Text Available Polymer shells with high sphericity and uniform wall thickness are always needed in the inertial confined fusion (ICF experiments. Driven by the need to control the shape of water-in-oil (W1/O compound droplets, the effects of the density matching level, the interfacial tension and the rotation speed of the continuing fluid field on the sphericity and wall thickness uniformity of the resulting polymer shells were investigated and the spherical and concentric mechanisms were also discussed. The centering of W1/O compound droplets, the location and movement of W1/O compound droplets in the external phase (W2 were significantly affected by the density matching level of the key stage and the rotation speed of the continuing fluid field. Therefore, by optimizing the density matching level and rotation speed, the batch yield of polystyrene (PS shells with high sphericity and uniform wall thickness increased. Moreover, the sphericity also increased by raising the oil/water (O/W2 interfacial tension, which drove a droplet to be spherical. The experimental results show that the spherical driving force is from the interfacial tension affected by the two relative phases, while the concentric driving force, as a resultant force, is not only affected by the three phases, but also by the continuing fluid field. The understanding of spherical and concentric mechanism can provide some guidance for preparing polymer shells with high sphericity and uniform wall thickness.

  13. Parabolic scaling beams.

    Science.gov (United States)

    Gao, Nan; Xie, Changqing

    2014-06-15

    We generalize the concept of diffraction free beams to parabolic scaling beams (PSBs), whose normalized intensity scales parabolically during propagation. These beams are nondiffracting in the circular parabolic coordinate systems, and all the diffraction free beams of Durnin's type have counterparts as PSBs. Parabolic scaling Bessel beams with Gaussian apodization are investigated in detail, their nonparaxial extrapolations are derived, and experimental results agree well with theoretical predictions.

  14. Basics of compounding: basics of compounding with aliquots, dilutions, and concentrates.

    Science.gov (United States)

    Allen, Loyd V

    2010-01-01

    Pharmacists involved in Compounding must consider a number of factors when determining the actual quantity of an active ingredient to use for a compounded prescription. Many drug substances and excipients are available as aliquots, dilutions, and concentrates and do not consist of 100% drug or chemical. Since the bulk substance, or active pharmaceutical ingredient or excipient is not 100% active drug in all cases, then it is important to know the strength of the item so that appropriate allowances can be made to obtain the correct amount.

  15. STUDY AND REALIZATION OF DEVICE OF SOLAR SENSITIVE TRACKING FOR A PROTOTYPE OF CYLINDRO-PARABOLIC CONCENTRATOR

    Directory of Open Access Journals (Sweden)

    A. Gama

    2015-08-01

    Full Text Available After the realization of a new prototype of concentrator through, we have study the realization of a sun tracking system in order to assure the best system efficiency throughout the day. We started in the first step by the blind sun tracking where we have acquired the good results. In this paper we try to speak about the realization of a new system of sun tracking who is the sensitive sun tracking. In this sort of tracking we have used a special telescope, like a sensitive element in for the detection of sun position. An electronic Card based PIC microcontroller is realized to pilot the mechanic system of the san tracking. In order to controlled the prototype we have put on a chain of data acquisition. The results were compared with the results of the blind sun tracking system and the stationary position, it was noted that the results were better this time and the efficiency is very important.

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

    Science.gov (United States)

    Isarain-Chávez, Eloy; Rodríguez, Rosa María; Cabot, Pere Lluís; Centellas, Francesc; Arias, Conchita; Garrido, José Antonio; Brillas, Enric

    2011-08-01

    The degradation of the beta-blockers atenolol, metoprolol tartrate and propranolol hydrochloride was studied by electro-Fenton (EF) and solar photoelectro-Fenton (SPEF). Solutions of 10 L of 100 mg L⁻¹ of total organic carbon of each drug in 0.1 M Na₂SO₄ with 0.5 mM Fe²⁺ of pH 3.0 were treated in a recirculation flow plant with an electrochemical reactor coupled with a solar compound parabolic collector. Single Pt/carbon felt (CF) and boron-doped diamond (BDD)/air-diffusion electrode (ADE) cells and combined Pt/ADE-Pt/CF and BDD/ADE-Pt/CF cells were used. SPEF treatments were more potent with the latter cell, yielding 95-97% mineralization with 100% of maximum current efficiency and energy consumptions of about 0.250 kWh g TOC⁻¹. However, the Pt/ADE-Pt/CF cell gave much lower energy consumptions of about 0.080 kWh g TOC⁻¹ with slightly lower mineralization of 88-93%, then being more useful for its possible application at industrial level. The EF method led to a poorer mineralization and was more potent using the combined cells by the additional production of hydroxyl radicals (•OH) from Fenton's reaction from the fast Fe²⁺ regeneration at the CF cathode. Organics were also more rapidly destroyed at BDD than at Pt anode. The decay kinetics of beta-blockers always followed a pseudo first-order reaction, although in SPEF, it was accelerated by the additional production of •OH from the action of UV light of solar irradiation. Aromatic intermediates were also destroyed by hydroxyl radicals. Ultimate carboxylic acids like oxalic and oxamic remained in the treated solutions by EF, but their Fe(III) complexes were photolyzed by solar irradiation in SPEF, thus explaining its higher oxidation power. NO₃⁻ was the predominant inorganic ion lost in EF, whereas the SPEF process favored the production of NH₄⁺ ion and volatile N-derivatives.

  17. Numerical Validation of a New Approach to Model Single Junction Low Concentration PV Cells under Non-Uniform Illumination

    National Research Council Canada - National Science Library

    Hang Zhou; Yuehong Su; Michele Bottarelli; Marco Bortoloni; Shenyi Wu

    2015-01-01

      This study presents a numerical validation of a new approach to model single junction PV cell under non-uniform illumination for low-concentration solar collectors such as compound parabolic concentrators (CPC...

  18. Solar light (hv) and H2O2/hv photo-disinfection of natural alkaline water (pH 8.6) in a compound parabolic collector at different day periods in Sahelian region

    OpenAIRE

    Ndounla, J.; Pulgarin, C

    2015-01-01

    The photo-disinfection of natural alkaline surface water (pH 8.6 +/- 0.3) for drinking purposes was carried out under solar radiation treatments. The enteric bacteria studied were the wild total coliforms/Escherichia coli (10(4) CFU/ml) and Salmonella spp. (10(4) CFU/ml) naturally present in the water. The photo-disinfection of a 25-l water sample was carried out in a solar compound parabolic collector (CPC) in the absence and in the presence of hydrogen peroxide (H2O2). The addition of H2O2 ...

  19. Parabolic trough systems; Parabolrinnensysteme

    Energy Technology Data Exchange (ETDEWEB)

    Geyer, M. [Flabeg Solar International GmbH (Germany); Lerchenmueller, H.; Wittwer, V. [Fraunhofer ISE, Freiburg (Germany); Haeberle, A. [PSE GmbH (Germany); Luepfert, E.; Hennecke, K. [DLR, Koeln (Germany); Schiel, W. [SBP (Germany); Brakmann, G. [Fichtner Solar GmbH (Germany)

    2002-07-01

    The technology of parabolic trough power plants is presented: History, comparative assessment of different types of parabolic trough collectors, fresnel collectors, solar tracking systems, thermal efficiency, further research, performance of the SEGS parabolic trough power station in California. [German] Die Technik von Parabolrinnen-Kraftwerken wird vorgestellt: Entwicklungsgeschichte, Vergleich verschiedener Parabolrinnenkollektoren, fresnel kollektoren, Nachfuehrsysteme, thermischer Wirkungsgrad, weiterer Forschungsbedarf und Betriebserfahrung mit dem SEGS Parabolrinnenkraftwerk in Kalifornien. (uke)

  20. DSG太阳能槽式集热器聚光特性模拟%Simulation on Concentrating Characteristics of DSG Parabolic Trough Collectors

    Institute of Scientific and Technical Information of China (English)

    韦彪; 朱天宇

    2011-01-01

    在槽式集热器光学理论的基础上,以DSG太阳能槽式真空集热器为研究对象,建立DSG集热器模型,并运用蒙特卡罗光线追踪法进行辐射计算及分析.通过研究集热器几何聚光比和边界角对集热器吸热管表面圆周方向热流密度分布的影响,获取了集热器的聚光特性.结果表明:计算结果与文献数据吻合良好;随着几何聚光比的增大,吸热管表面圆周方向的热流密度分布趋势不变,数值相应增大;随着集热器边界角的减小,热流密度的最大值增大,热流密度的分布曲线向圆周角-90°方向偏移相应的角度.%Based on optical properties of parabolic trough solar collector,models for such a DSG vacuum collector were established so as to perform relevant solar radiation calculation and analysis by Monte Carlo Ray-Trace Method(MCRT).To investigate the concentrating characteristics,the effects of geometry concentration ratios and rim angles on heat flux distribution around the heat-absorbing tube in circumferential direction were studied.Simulation results show that the predicted results agree well with the data in reference materials;with increasing geometric concentration ratio,the distribution tendency of heat flux in circumferential direction keeps the same,but the value rises;with decreasing rim angle,the maximum value of heat flux in circumferential direction increases,and the distribution curve moves to the direction of circle angle-90°.

  1. 槽式太阳能聚光器太阳跟踪液压驱动系统设计%The Design of Hydraulic Drive Control System For Parabolic Concentrator Sun-tracking Mechanism

    Institute of Scientific and Technical Information of China (English)

    谢超; 罗馨茹; 俞竹青

    2012-01-01

    槽式太阳能热发电系统中,其聚光器太阳跟踪性能是太阳能采集率的重要影响因素.设计了一套槽式太阳能聚光器太阳跟踪机构专用的中高压液压驱动控制系统,并系统采用了比例溢流阀和比例流量阀,因此具有驱动力矩大、启动平稳、跟踪精度高的特点.实验证明了其设计的正确性和可靠性.%In solar parabolic trough thermal power (SPTTP) system, the parabolic concentrator sun— tracking performance has significant influence on solar collection rate. A set of special —purpose hydraulic drive control system is developed for sun—tracking mechanism of Parabolic Concentrator. It has the features of great driving force, stable starting and accurate positioning. Testing and the actual use have proved the correctness, feasibility and reliability of proposed design.

  2. Trichloromethyl compounds - natural background concentrations and fates within and

    DEFF Research Database (Denmark)

    Albers, Christian Nyrop; Hansen, Poul Erik; Jacobsen, Ole Stig

    2010-01-01

    occurrence and cycling of organic compounds with a trichloromethyl moiety in common. The study areas are temperate coniferous forests. Trichloromethyl compounds can be found in all compartments of the forests (groundwater, soil, vegetation and throughfall), but not all compounds in all compartments...

  3. Parabolic Dish Stirling Module

    Science.gov (United States)

    Washom, B.

    1984-01-01

    The design, manufacture, and assembly of a commercially designed parabolic dish Stirling 25 kWe module is examined. The cost, expected performance, design uniquenesses, and future commercial potential of this module, which is regarded as the most technically advanced in the parabolic dish industry is discussed.

  4. Trichloromethyl compounds - natural background concentrations and fates within and

    DEFF Research Database (Denmark)

    Albers, Christian Nyrop; Hansen, Poul Erik; Jacobsen, Ole Stig

    2010-01-01

    occurrence and cycling of organic compounds with a trichloromethyl moiety in common. The study areas are temperate coniferous forests. Trichloromethyl compounds can be found in all compartments of the forests (groundwater, soil, vegetation and throughfall), but not all compounds in all compartments....... The atmospheric input of trichloromethyl compounds is found to be minor, with significant contributions for trichloroacetic acid (TCAA), only. In top soil, where the formation of the compounds is expected to occur, there is a clear positive relationship between chloroform and trichloroacetyl containing compounds....... Other positive relations occur, which in combination with chlorination experiments performed in the laboratory, point to the fact that all the trichloromethyl compounds may be formed concurrently in the soil, and their subsequent fates then differ due to different physical, chemical and biological...

  5. Project, fabrication, assembly and tests of different prototypes for CPS compound parabolic solar collectors; Projeto, fabricacao, montagem e testes de diferentes prototipos de coletores solares parabolicos compostos CPCs

    Energy Technology Data Exchange (ETDEWEB)

    Neto, Jose H.M. [Centro Federal de Educacao Tecnologica de Minas Gerais (CEFET), Belo Horizonte, MG (Brazil). Dept. de Engenharia Mecanica]. E-mail: henrique@daem.des.cefemg.br

    2000-07-01

    This work presents the results of the experiment involving the design, fabrication, assembly and tests of composite parabolic solar collectors prototypes with acceptance half-angles of 3 deg C, 6.5 deg C, 11 deg C, 14 deg C and 19.5 deg C of the tube type absorber and 14 deg C rectangular absorber. Field test were performed on all the prototypes for determination of thermal efficiency, time constants and optical efficiencies represented by the modified incidence angles. Tests were performed for the determination of the heat transfer global coefficients on each prototype. (author)

  6. Mineral resource analysis by parabolic fractals

    Institute of Scientific and Technical Information of China (English)

    XIE Shu-yun; YANG Yong-guo; BAO Zheng-yu; KE Xian-zhong; LIU Xiao-long

    2009-01-01

    Elemental concentration distributions in space have been analyzed using different approaches. These analyses are of great significance for the quantitative characterization of various kinds of distribution patterns. Fractal and multi-fiactal methods have been extensively applied to this topic. Traditionally, approximately linear-fractal laws have been regarded as useful tools for characterizing the self-similarities of element concentrations. But, in nature, it is not always easy to fred perfect linear fractal laws. In this paper the parabolic fractal model is used. First a two dimensional multiplicative multi-fractal cascade model is used to study the concentration patterns. The results show the parabolic fractal (PF) properties of the concentrations and the validity of non-linear fractal analysis. By dividing the studied area into four sub-areas it was possible to show that each part follows a non-linear para-bolic fractal law and that the dispersion within each part varies. The ratio of the polynomial coefficients of the fitted parabolic curves can reflect, to some degree, the relative concentration and dispersal distribution patterns. This can provide new insight into the ore-forming potential in space. The parabolic fractal evaluations of ore-forming potential for the four subareas are in good agreement with field investigation work and geochemical mapping results based on analysis of the original data.

  7. 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.)

  8. Serum Vaccine Antibody Concentrations in Children Exposed to Perfluorinated Compounds

    DEFF Research Database (Denmark)

    Grandjean, P.; Andersen, E. W.; Budtz-Jorgensen, E.

    2012-01-01

    in follow-up through 2008. Main Outcome Measures Serum antibody concentrations against tetanus and diphtheria toxoids at ages 5 and 7 years. Results Similar to results of prior studies in the United States, the PFCs with the highest serum concentrations were perfluorooctane sulfonic acid (PFOS...... concentration. PFCs in the child's serum at age 5 years showed uniformly negative associations with antibody levels, especially at age 7 years, except that the tetanus antibody level following PFOS exposure was not statistically significant. In a structural equation model, a 2-fold greater concentration.......44) for falling below a clinically protective level of 0.1 IU/mL for tetanus and diphtheria antibodies at age 7 years. Conclusion Elevated exposures to PFCs were associated with reduced humoral immune response to routine childhood immunizations in children aged 5 and 7 years. JAMA. 2012;307(4):391-397...

  9. Serum Vaccine Antibody Concentrations in Adolescents Exposed to Perfluorinated Compounds

    DEFF Research Database (Denmark)

    Grandjean, Philippe; Heilmann, Carsten; Weihe, Pal

    2017-01-01

    BACKGROUND: Postnatal exposure to perfluorinated alkylate substances (PFASs) is associated with lower serum concentrations of specific antibodies against certain childhood vaccines at age 7 years. OBJECTIVES: We prospectively followed a Faroese birth cohort to determine these associations at age ...

  10. Parabolic Strip Telescope

    CERN Document Server

    Chadzitaskos, Goce

    2013-01-01

    We present a proposal of a new type of telescopes using a rotating parabolic strip as the primary mirror. It is the most principal modification of the design of telescopes from the times of Galileo and Newton. In order to demonstrate the basic idea, the image of an artificial constellation observed by this kind of telescope was reconstructed using the techniques described in this article. As a working model of this new telescope, we have used an assembly of the primary mirror---a strip of acrylic glass parabolic mirror 40 cm long and 10 cm wid shaped as a parabolic cylinder of focal length 1 m---and an artificial constellation, a set of 5 apertures in a distance of 5 m illuminated from behind. In order to reconstruct the image, we made a series of snaps, each after a rotation of the constellation by 15 degrees. Using Matlab we reconstructed the image of the artificial constellation.

  11. Design research and p erformance analysis of comp ound parab olic concentrators as optical antennas in visible light communication%复合抛物面聚光器作为可见光通信光学天线的设计研究与性能分析∗

    Institute of Scientific and Technical Information of China (English)

    王云; 蓝天; 李湘; 沈振民; 倪国强

    2015-01-01

    In order to satisfy the need of visible light communication, compound parabolic concentrators are selected as the optical antennas because of their wide fields of view and high gains in small field of view. Their geometries and optical properties are introduced in order to design compound parabolic concentrators with different fields of view by TracePro. These compound parabolic concentrators are tested under different light source conditions. The distribution of the received power of the receiver which has been coupled with the compound parabolic concentrator, is obtained by a simulation. The obtained gain of compound parabolic concentrator proves that the compound parabolic concentrator works better when the light source has a Lambert radiation pattern than the case under a parallel light condition. The results illustrate that compound parabolic concentrator is suitable to serving as an optical antenna for visible light communication. And it also shows that the smaller the field of view, the greater the gain is. Under the condition of simulation in this paper, a compound parabolic concentrator with 10◦ field of view could realize a gain of 22.88, which is 31% lower than the theoretical gain because of the effect of its position relative to the light source. On this basis, the model of a visible light communication system is established in a room with a size of 5 m × 5 m × 3 m. By using a compound parabolic concentrator with a field of view of 60◦ as an optical antenna, the simulation results show that the average received power is increased by 4.29 dBm for the directed light from light emitting diodes, and by 4.77 dBm with the reflected light being included. And the average received power is increased by 11.2%when the reflected light is considered.

  12. Parabolic k-ample bundles

    CERN Document Server

    Biswas, Indranil

    2011-01-01

    We construct projectivization of a parabolic vector bundle and a tautological line bundle over it. It is shown that a parabolic vector bundle is ample if and only if the tautological line bundle is ample. This allows us to generalize the notion of a k-ample bundle, introduced by Sommese, to the context of parabolic bundles. A parabolic vector bundle $E_*$ is defined to be k-ample if the tautological line bundle ${\\mathcal O}_{{\\mathbb P}(E_*)}(1)$ is $k$--ample. We establish some properties of parabolic k-ample bundles.

  13. Concentrations of organochlorine pesticides, polybrominated diphenyl ethers and perfluorinated compounds in the atmosphere of North Greenland

    DEFF Research Database (Denmark)

    Bossi, Rossana; Vorkamp, Katrin; Skov, Henrik

    2016-01-01

    sulfonamides (FOSA) and perfluoroalkyl sulfonamidoethanols (FOSE) were also detected but at much lower concentrations than FTOHs. Temporal trends were investigated for all measured compounds but no significant trend in concentration was observed. Monthly average concentrations for the six years were calculated...

  14. Session: Parabolic Troughs (Presentation)

    Energy Technology Data Exchange (ETDEWEB)

    Kutscher, C.

    2008-04-01

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

  15. Parabolic Stein Manifolds

    CERN Document Server

    Aytuna, Aydin

    2011-01-01

    An open Riemann surface is called parabolic in case every bounded subharmonic function on it reduces to a constant. Several authors introduced seemingly different analogs of this notion for Stein manifolds of arbitrary dimension. In the first part of this note we compile these notions of parabolicity and give some immediate relations among them. In section 3 we relate some of these notions to the linear topological type of the Fr\\'echet space of analytic functions on the given manifold. In sections 4 and 5 we look at some examples and show, for example, that the complement of the zero set of a Weierstrass polynomial possesses a continuous plurisubharmonic exhaustion function that is maximal off a compact subset.

  16. Mahonians and parabolic quotients

    CERN Document Server

    Caselli, Fabrizio

    2011-01-01

    We study the distribution of the major index with sign on some parabolic quotients of the symmetric group, extending and generalizing simultaneously results of Panova [G. Panova, Bijective enumeration of permutations starting with a longest increasing subsequence, Discrete Math. Theor. Comput. Sci. Proc. AN (2010), 841--850], Gessel-Simion [M. Wachs, An involution for signed Eulerian numbers, Discrete Math. 99 (1992), 59--62] and Adin-Gessel-Roichman [R. Adin, I. Gessel and Y. Roichman, Signed Mahonians, J. Combin. Theory Ser. A 109 (2005), 25--43]. We further consider and compute the distribution of the flag-major index on some parabolic quotients of wreath products and other related groups. All these distributions turn out to have very simple factorization formulas.

  17. 槽式聚光热电联供系统抛物反射面的性能参数分析%Performance parameters analysis on the parabolic concentrator in solar trough based combined heat and power system

    Institute of Scientific and Technical Information of China (English)

    罗熙; 李明; 王云峰; 李国良; 魏生贤; 王炳灿

    2011-01-01

    The influences of tracking mode and solar intercept angle on the ideal trough parabolic mirror were analyzed.The functional relationships among the geometric concentration ratio of system, the relative aperture of concentrator, energy flux distribution and the rim angle were presented.Under the ideal condition, the maximum concentration ratio of the trough concentrator is 212.59 while the rim angle δ is 44.87 ° and the relative aperture is 1.652 m.The cosine values of incidence angles in singleaxis tracking mode were calculated in Beijing, Shanghai and Kunming at different times throughout the year.The results showed the cosine values of the incidence angle have nothing to do with the latitudes when adopting east-west horizontal axis tracking mode.However, the incidence angle changes a lot in spring and winter, but that changes a little in summer and autumn.Considering different widths of solar cells and concentration ratios, the parameters of trough style parabolic mirror were also been designed and analyzed.%分析了跟踪方式和太阳张角对理想槽式抛物面反射镜的影响,给出了几何聚光比、相对口径、能流分布、边界角之间的函数关系式.在理想情况下,边界角δ为44.87°时,槽式聚光器的最大聚光比为212.59,此时相对口径为1.652 m.讨论了北京、上海、昆明等地单轴跟踪在全年不同时刻入射角余弦值的变化规律.采取东-西水平轴跟踪时,入射角余弦值与各地纬度无关;采取南-北水平轴跟踪时,春冬两季每天不同时刻入射角的变化范围较大,夏秋两季的变化范围较小.文章针对不同宽度太阳电池和聚光比对抛物镜面参数进行了设计分析.

  18. Iridium concentration driving the mechanical properties of iridium–aluminum compounds

    Energy Technology Data Exchange (ETDEWEB)

    Pan, Y. [School of Materials Science and Engineering, Southwest Petroleum University, Chengdu 610500 (China); Wen, M. [State Key Laboratory of Advanced Technologies for Comprehensive Utilization of Platinum Metals, Kunming 650106 (China); Wang, L.; Wang, X. [School of Materials Science and Engineering, Southwest Petroleum University, Chengdu 610500 (China); Lin, Y.H., E-mail: yhlin28@163.com [School of Materials Science and Engineering, Southwest Petroleum University, Chengdu 610500 (China); Guan, W.M., E-mail: gwm@ipm.com.cn [State Key Laboratory of Advanced Technologies for Comprehensive Utilization of Platinum Metals, Kunming 650106 (China)

    2015-11-05

    Using first-principles density functional theory approach, we systematically investigate the formation enthalpy, mechanical stability, elastic modulus, brittle or ductile behavior and electronic structure of Ir–Al compounds with different Ir concentrations. The calculated convex hull indicates that IrAl with CsCl-type structure is more stability than that of other Ir–Al compounds at ground state. We found that the resistance to volume deformation is related to the Ir concentration in Ir–Al compounds, while the bulk modulus of these compounds increases with increasing Ir concentrations. However, the Ir{sub 5}Al{sub 3} has the strongest shear deformation resistance and has the highest elastic stiffness in these Ir–Al compounds. The calculated theoretical hardness of Ir{sub 2}Al{sub 9} is bigger than other Ir–Al compounds. Ir{sub 2}Al{sub 3} and Ir{sub 2}Al{sub 9} exhibit brittle behavior in contrast to other Ir–Al compounds exhibit ductile behavior. This discrepancy is originated from the structural feature and localized hybridization between Ir and Al atoms. Finally, we conclude that alloying can change brittle behavior of metal Ir. - Highlights: • The correlation between Ir concentration and mechanical properties is studied. • The convex hull indicates that IrAl is the most stable structure. • We found that alloying can weaken the brittle behavior of metal Ir. • We found that the bulk modulus of Ir–Al compound is related to Ir concentration. • The theoretical hardness of Ir{sub 2}Al{sub 9} is higher than other Ir–Al compounds.

  19. Thermogravimetric Analysis of the Zinc Concentrates Oxidation Containing Various Iron Compounds

    Directory of Open Access Journals (Sweden)

    Małecki S.

    2014-10-01

    Full Text Available This paper presents the results of oxidation of zinc concentrates containing various iron compounds. Using the thermogravimetry and thermal analysis methods it was shown that the influence of the iron form affects the thermal oxidation process. They influence the rate of, oxidation of zinc sulphide and consequently the resulting rate of oxidation of the concentrate.

  20. Courant Algebroids in Parabolic Geometry

    CERN Document Server

    Armstrong, Stuart

    2011-01-01

    To a smooth manifold $M$, a parabolic geometry associates a principal bundle, which has a parabolic subgroup of a semisimple Lie group as its structure group, and a Cartan connection. We show that the adjoint tractor bundle of a regular normal parabolic geometry can be endowed with the structure of a Courant algebroid. This gives a class of examples of transitive Courant algebroids that are not exact.

  1. Proceedings of the Fifth Parabolic Dish Solar Thermal Power Program

    Science.gov (United States)

    Lucas, J. W. (Editor)

    1984-01-01

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

  2. Indoor carbonyl compounds in an academic building in Beijing, China: concentrations and influencing factors

    Institute of Scientific and Technical Information of China (English)

    Chuanjia JIANG; Pengyi ZHANG

    2012-01-01

    Carbonyl compounds in indoor air are of great concern for their adverse health effects. Between February and May, 2009, concentrations of 13 carbonyl compounds were measured in an academic building in Beijing, China. Total concentration of the detected carbonyls ranged from 20.7 to 189.1 I.tg.m3, and among them acetone and formaldehyde were the most abundant, with mean concentrations of 26.4 and 22.6gg.m-3, respectively. Average indoor concentrations of other carbonyls were below I 0 gg. m~3. Principal component analysis identified a combined effect of common indoor carbonyl sources and ventilation on indoor carbonyl levels. Diurnal variations of the carbonyl compounds were investigated in one office room, and carbonyl concentrations tended to be lower in the daytime than at night, due to enhanced ventilation. Average concentrations of carbonyl compounds in the office room were generally higher in early May than in late February, indicating the influence of temperature. Carbo- nyl source emission rates from both the room and human occupants were estimated during two lectures, based on one-compartment mass balance model. The influence of human occupants on indoor carbonyl concentrations varies with environmental conditions, and may become signifi- cant in the case of a large human occupancy.

  3. Autotrophic denitrification for treatment of wastewater with high concentration of sulphur and nitrogen compounds

    OpenAIRE

    Fajardo Ortiz, María del Carmen

    2011-01-01

    Anthropogenic activities have contributed to the imbalance of nitrogen and sulphur natural cycles which causes many negative effects in nature due to the emissions of sulphur and nitrogen compounds and their transformations, e.g. rain acid, eutrophication, bad odours etc. To avoid such negative effects on environment, effluents containing high concentrations of both nitrogen and sulphur compounds must be treated previously to their discharge. Nitrification/denitrification is the conventio...

  4. 基于复合抛物面集光器的LED教室灯具的配光设计%Light distribution design of LED lamps in classroom based on compound parabolic collector

    Institute of Scientific and Technical Information of China (English)

    白莹; 林文硕; 谢国庆

    2014-01-01

    A compound parabolic collector light distribution system was established for light dis-tribution of LED lamps in the classroom .First the characteristics of the LED light source were analyzed ,as well as the necessity of the secondary light distribution for the LED light source . The 3D nonimaging optics compound parabolic collector (CPC) model was established .The re-lationship between its parameters and the maximum exit half angle θm was calculated by the edge light principle and the restricting factors of θm were given .Then the values of all parame-ters of CPC model were determined according to the reading lamp illumination uniformity re-quirements ,the CPC model was built in the optical analysis software Tracepro .The LED light source was placed on the focal plane of CPC model and the LED classroom lighting illumination distribution based on CPC was simulated combining with classroom desktop and the lamp dis-tance .Results showed that the light uniformity cound reach more than 0 .7 and satisfy the building lighting design standard GB 50034-2004 for reading lighting requirements as θm was greater than 30° ,the effective optical flux was more than 95% .%为了对L ED教室灯具配光,建立了复合抛物面集光器配光系统。分析了L ED光源发光特性,阐明了对L ED光源进行二次配光的必要性。建立了三维复合抛物面集光器(C PC )模型,并由边缘光线原理计算得出三维复合抛物面集光器(C PC )模型各参数与最大出射半角θm 的关系,分析了θm 的制约因素。由阅读灯照度均匀度要求,确定了复合抛物面集光器(C PC )模型各参数的值,在光学分析软件Tracepro中建立了CPC模型,将LED光源置于其焦平面上,结合教室桌面与灯具距离,模拟了基于C PC配光的L ED教室灯具的照度分布。试验结果表明,C PC配光系统最大出光半角为30°时,光照均匀度超过0.7,满足建筑照明设计标准 GB 50034

  5. Concentrations of volatile organic compounds at a building with health and comfort complaints.

    Science.gov (United States)

    Weschler, C J; Shields, H C; Rainer, D

    1990-05-01

    For four separate periods over a 1-yr span, the concentrations of volatile organic compounds (VOCs) have been measured at a facility with a history of occupant complaints. The reported symptoms were characteristic of "sick building syndrome." This study was initiated to determine if VOC levels were higher than those measured in "complaint-free" buildings and, if so, to identify sources and other factors that might contribute to the elevated concentrations. VOCs were collected with passive samplers, using a sampling interval that lasted from 3 to 4 weeks. Following collection, the samplers were extracted, and the compounds in the extract were separated and identified using standard gas chromatographic-mass spectrometric procedures. Over 40 different organic compounds with concentrations in excess of 1 microgram/m3 were identified; several species had values greater than 100 micrograms/m3. For each of the first three sampling periods, the total concentration of VOCs detected using this methodology was in excess of 3 mg/m3. Sources of the identified compounds included cleaning products, floor wax, latex paints, and reentrained motor vehicle exhaust. However, the dominant source was the hydraulic system for the buildings' elevators. Compounds were volatilizing from the hydraulic fluid used in this system. Neither the elevator shafts nor the mechanical room housing the fluid reservoirs were vented to the outside. The problem was compounded by the relatively small amount of outside air used for ventilation at this facility (less than 6 L/sec [12 cfm]/occupant or about 1/4 air change/hr). At such low ventilation rates, compounds with strong sources can achieve high steady-state concentrations within the facility. Recommendations have been made to reduce the VOC levels at this site. Although implementing the recommendations will be costly, even a slight improvement in employee productivity will offset these costs.

  6. Mathematical modeling of atmospheric fine particle-associated primary organic compound concentrations

    Science.gov (United States)

    Rogge, Wolfgang F.; Hildemann, Lynn M.; Mazurek, Monica A.; Cass, Glen R.; Simoneit, Bernd R. T.

    1996-08-01

    An atmospheric transport model has been used to explore the relationship between source emissions and ambient air quality for individual particle phase organic compounds present in primary aerosol source emissions. An inventory of fine particulate organic compound emissions was assembled for the Los Angeles area in the year 1982. Sources characterized included noncatalyst- and catalyst-equipped autos, diesel trucks, paved road dust, tire wear, brake lining dust, meat cooking operations, industrial oil-fired boilers, roofing tar pots, natural gas combustion in residential homes, cigarette smoke, fireplaces burning oak and pine wood, and plant leaf abrasion products. These primary fine particle source emissions were supplied to a computer-based model that simulates atmospheric transport, dispersion, and dry deposition based on the time series of hourly wind observations and mixing depths. Monthly average fine particle organic compound concentrations that would prevail if the primary organic aerosol were transported without chemical reaction were computed for more than 100 organic compounds within an 80 km × 80 km modeling area centered over Los Angeles. The monthly average compound concentrations predicted by the transport model were compared to atmospheric measurements made at monitoring sites within the study area during 1982. The predicted seasonal variation and absolute values of the concentrations of the more stable compounds are found to be in reasonable agreement with the ambient observations. While model predictions for the higher molecular weight polycyclic aromatic hydrocarbons (PAH) are in agreement with ambient observations, lower molecular weight PAH show much higher predicted than measured atmospheric concentrations in the particle phase, indicating atmospheric decay by chemical reactions or evaporation from the particle phase. The atmospheric concentrations of dicarboxylic acids and aromatic polycarboxylic acids greatly exceed the contributions that

  7. Solar light (hv) and H2O2/hv photo-disinfection of natural alkaline water (pH 8.6) in a compound parabolic collector at different day periods in Sahelian region.

    Science.gov (United States)

    Ndounla, J; Pulgarin, C

    2015-11-01

    The photo-disinfection of natural alkaline surface water (pH 8.6 ± 0.3) for drinking purposes was carried out under solar radiation treatments. The enteric bacteria studied were the wild total coliforms/Escherichia coli (10(4) CFU/ml) and Salmonella spp. (10(4) CFU/ml) naturally present in the water. The photo-disinfection of a 25-l water sample was carried out in a solar compound parabolic collector (CPC) in the absence and in the presence of hydrogen peroxide (H2O2). The addition of H2O2 (10 mg/L) to the sample water was sufficient to enhance the photo-disinfection and ensure an irreversible lethal action on the wild enteric bacteria contents of the sample. The inactivation kinetic of the system was significantly enhanced compared to the one carried out without H2O2 addition. The effect of the solar radiation parameters on the efficiency of the photo-disinfection were assessed. The pH has increased during the treatment in all the photo-disinfection processes (hv and H2O2/hv). The Salmonella spp strain has shown the best effective inactivate time in alkaline water than the one recorded under acidic or near-neutral conditions. The evolution of some physico-chemical parameters of the water (turbidity, NO2(-), NO3(-), NH4(+), HPO4(2-), and bicarbonate (HCO3(-))) was monitored during the treatment. Finally, the possible mechanistic process involved during the enteric bacteria inactivation was suggested.

  8. Concentrations of organochlorine pesticides, polybrominated diphenyl ethers and perfluorinated compounds in the atmosphere of North Greenland.

    Science.gov (United States)

    Bossi, Rossana; Vorkamp, Katrin; Skov, Henrik

    2016-10-01

    Atmospheric concentrations of organochlorine pesticides (OCPs), polybrominated diphenyl ethers (PBDEs) and neutral per- and polyfluoroalkyl substances (PFAS) have been measured at Villum Research Station, Station Nord (North Greenland) in the period 2008-2013. Atmospheric concentrations of OCPs at the same site have been previously reported for the years 2008-2010. The detection frequency and the average concentrations of OCPs have not significantly changed since the previous study. PBDE congeners (∑13PBDEs) were measured for the first time in North Greenland at concentrations similar to those observed for other remote sites, confirming that these compounds are ubiquitous in the Northern Hemisphere. The ∑13PBDEs concentration ranged from not detected (n.d.) to 6.26 pg m(-3). The BDE congeners found in more than 30% of the samples were BDE-17, BDE-28, BDE-47, BDE-71, BDE-99 and BDE-100. Also for neutral PFAS we present for the first time a multiyear series of measurements for North Greenland. The average sum of the seven measured neutral PFAS (∑7PFAS) ranged from 1.82 to 32.1 pg m(-3). The most abundant compound was 8:2 FTOH (44% of ∑7PFAS), followed by 6:2 FTOH and 10:2 FTOH. Perfluoroalkyl sulfonamides (FOSA) and perfluoroalkyl sulfonamidoethanols (FOSE) were also detected but at much lower concentrations than FTOHs. Temporal trends were investigated for all measured compounds but no significant trend in concentration was observed. Monthly average concentrations for the six years were calculated for each compound and the seasonal variation was investigated. Some OCPs and FTOHs showed seasonal variations, and in most cases a maximum was found during summer.

  9. Mineral and organic compounds in leachate from landfill with concentrate recirculation.

    Science.gov (United States)

    Talalaj, Izabela Anna

    2015-02-01

    The effect of a reverse osmosis concentrate recirculation on the mineral and organic compounds in a landfill leachate was investigated. Investigated was the quality of a leachate from two landfills operated for different periods (a 20-year-old Cell A and a 1-year-old Cell B), where the concentrate was recirculated. Examined were general parameters (conductivity, pH), organic compounds (biochemical oxygen demand (BOD), chemical oxygen demand (COD), total organic nitrogen, BOD/COD), and inorganic compounds (nitrogen ammonia, sulfite, sulfate, cyanide, boron, chloride, ferrous, zinc, chrome, copper). The findings from the first year of investigation showed that over the initial period of recirculation, the concentration of organic compounds (BOD, COD) increased, but after 6 months their values stabilized. It indicates that the concentrate recirculation accelerated organic decomposition, especially in the new landfill Cell. The analysis of inorganic parameters showed that recirculation landfills produce a leachate with a higher concentration of N-NH4, and Cl(-). In case of the old landfill Cell, an increase in B and Fe was also noticeable. These compounds are cyclically washed out from a waste dump and require an additional pretreatment in order to exclude them from recirculation cycle. The increased concentration of Cu, Zn, and Fe was noticed during the initial months of recirculation and in the season of intense atmospheric precipitation in the leachate from both Cells. Higher values of electro conductivity, Cl(-), N-NH4 (+), B, and Fe in the leachate from the old field indicate that the attenuation capacity of this landfill is close to exhaustion.

  10. Aluminium and Aroma Compound Concentration in Beer During Storage at Different Temperatures

    Directory of Open Access Journals (Sweden)

    Marija Soldo Gjeldum

    2006-01-01

    Full Text Available Problem of aluminium in beer has been elaborated in several papers over the last decade. However, the effect of aluminium on organoleptic properties of beer has been observed in few papers where it has been stated that aluminium gives beer a »metallic« and bitter flavour without any observations on particular aroma compound changes. Also, the number of reports on precise changes of aroma components throughout different storage conditions is surprisingly scarce. In order to investigate the changes of aluminium concentration along with aroma compound changes, graphite furnace-atomic absorption spectrophotometry (GF-AAS with Zeeman background correction and gas chromatography with static headspace sampler (GC-HSS were used in this work. Analyses were conducted periodically throughout seven months of storage on three different brands of beer from name breweries. Samples were taken before and after filling in aluminium cans. One part of samples was stored in a refrigerator (4 °C and the other in a thermostatic chamber (22 °C. The effects of beer brand and storage conditions on aluminium concentration and level of aroma compounds were measured. To prove the effect of aluminium concentration on the changes of aroma compounds, the adequate level of aluminium sulphate was added to bottled beer samples stored at 28 °C. Although different beer types showed significantly different aluminium concentration, it could be the result of other factors (different batches of identical beer type showed significantly different aluminium concentration as well. Samples that were stored in the refrigerator were protected from aluminium migration from the can to the beer and showed increased aroma stability. Level of aroma constituents of analyzed beer brands was significantly different. Elevated aluminium concentration did not have any noticeable effect on the level of aroma compounds in beer samples stored at 28 °C.

  11. Modelling day-time concentrations of biogenic volatile organic compounds in a boreal forest canopy

    Directory of Open Access Journals (Sweden)

    H. K. Lappalainen

    2010-08-01

    Full Text Available Three different models for day-time atmospheric methanol, acetaldehyde, acetone, isoprene and monoterpene concentrations were developed using measurements above a boreal forest stand in Southern Finland in 2006–2007 and tested against an independent dataset from the same forest measured in summer 2008. The models were based on the exponential relationship between air temperature and the concentration of biogenic volatile organic compounds (BVOC. Our first model for BVOC concentrations was a simple exponential function of air temperature (T-model. The T-model could explain 27–66% of the variation of all the compounds, but it failed to catch the extremely high concentration peaks observed in summer. To improve the temperature model we developed two other models. The second model, a Temperature-State of Development- model (T-S model, included two explaining variables: air temperature and the seasonal photosynthetic efficiency. This model performed slightly better compared to the T-model for both datasets and increased the fraction of variation explained to 29–69%, but it still could not explain the high concentration peaks. To explain those we modified the T-S model to include environmental triggers that could increase the concentrations momentarily. The triggers that improved the model most were high photosynthetically active photon flux density (PPDF compared to the seasonally available radiation and high ozone concentration. The Trigger model described the peak concentrations somewhat better than T or T-S model, thus the level of explanation was improved and was 30–71%. This study shows the importance to include seasonal variations in photosynthetic efficiency when modeling BVOC concentrations and presents the idea of a trigger model for explaining high peak concentrations of BVOCs. Our study suggests that when developing a trigger type modelfurther the model and the triggers should be more compounds-specific.

  12. Optimal geometry and dimensions for the receiver of a parabolic solar concentrator with an angle of 90 degrees; Determiancion de la geometria y dimensiones optimas de un receptor para un concentrador solar paraboloidal con angulo de apertura de 90 grados

    Energy Technology Data Exchange (ETDEWEB)

    Estrada, Claudio A; Arancibia, Camilo [Centro de Investigacion en Energia UNAM, Temixco, Morelos (Mexico); Hernandez, Nestor [Centro Nacional de Investigacion y Desarrollo Tecnologico, Cuernavaca, Morelos (Mexico)

    2000-07-01

    The optimal geometry and dimensions for the receiver of a parabolic solar concentrator based on microwave communication antenna are obtained. First, the experiments for the determination of the angular error of the concentrator and the dimensions of its focal region are described. Results are also presented for the ray tracing study, from which the optimal characteristics of the receiver are obtained according to the experimental results. As the aluminum antenna has a rim angle of 90 Celsius degrees, it is necessary to use a cavity receiver to allow external as well as internal absorption of radiative flux. Cylindrical, conical and spherical geometric were considered, as well as combinations of them. The best results are achieved using a conical cavity. Its dimensions are calculated to maximize the radiative transfer efficiency from the aperture of the concentrator to the receiver. [Spanish] Se determinan la geometria y dimensiones optimas del receptor de un concentrador solar parabolico obtenido a partir de una antena de telecomunicaciones para microondas. Primeramente se describen los experimentos realizados para obtener el valor del error angular asociado al concentrador y de las dimensiones de su region focal. Tambien se presentan los resultados del estudio optico de trazado de rayos, que permitio determinar teoricamente las caracteristicas del receptor, de acuerdo a los resultados de los experimentos. Debido a que la antena de aluminio tiene un angulo de borde de 90 grados Celcius, es necesario usar un receptor tipo cavidad que permita la captacion de energia tanto interna como externa. Se consideraron geometrias cilindrica, conica, esferica y combinaciones entre ellas, resultando ser la conica la que da los mejores resultados. Las dimensiones del receptor fueron determinadas maximizando la eficiencia del transporte de radiacion de la apertura del concentrador al receptor.

  13. Changes in volatile compounds in whey protein concentrate stored at elevated temperature and humidity

    Science.gov (United States)

    Whey protein concentrate (WPC) has been recommended for use in emergency aid programs, but it is often stored overseas without temperature and relative humidity (RH) control, which may cause it to be rejected because of yellowing, off-flavors, or clumping. Therefore, the volatile compounds present ...

  14. Seasonal trends in concentrations and fluxes of volatile organic compounds above central London

    Directory of Open Access Journals (Sweden)

    A. C. Valach

    2015-03-01

    Full Text Available Concentrations and fluxes of seven volatile organic compounds (VOCs were measured between August and December 2012 at a roof-top site in central London as part of the ClearfLo project (Clean Air for London. VOC concentrations were quantified using a proton transfer reaction-mass spectrometer and fluxes were calculated using a virtual disjunct eddy covariance technique. The median VOC fluxes, including aromatics, oxygenated compounds and isoprene, ranged from 0.07 to 0.33 mg m−2 h−1 and mixing ratios were 7.27 ppb for methanol (m / z 33 and <1 ppb for the remaining compounds. Strong relationships were observed between most VOC fluxes and concentrations with traffic density, but also with photosynthetically active radiation (PAR and temperature for the oxygenated compounds and isoprene. An estimated 50–90 % of aromatic fluxes were attributable to traffic activity, which showed little seasonal variation, suggesting boundary layer effects or possibly advected pollution may be the primary causes of increased concentrations of aromatics in winter. PAR and temperature-dependent processes accounted for the majority of isoprene, methanol and acetaldehyde fluxes and concentrations in August and September, when fluxes and concentrations were largest. Modelled biogenic isoprene fluxes using the G95 algorithm agreed well with measured fluxes in August and September, due to urban vegetation. Comparisons of estimated annual benzene emissions from the London and National Atmospheric Emissions Inventory agreed well with measured benzene fluxes. Flux footprint analysis indicated emission sources were localized and that boundary layer dynamics and source strengths were responsible for temporal and spatial VOC flux and concentration variability during the measurement period.

  15. Determinants of serum concentrations of organochlorine compounds in Swedish pregnant women: a cross-sectional study

    Directory of Open Access Journals (Sweden)

    Cnattingius Sven

    2007-02-01

    Full Text Available Abstract Background We performed a cross-sectional study of associations between personal characteristics and lipid-adjusted serum concentrations of certain PCB congeners and chlorinated pesticides/metabolites among 323 pregnant primiparous women from Uppsala County (age 18–41 years sampled 1996–1999. Methods Extensive personal interviews and questionnaires about personal characteristics were performed both during and after pregnancy. Concentrations of organochlorine compounds in serum lipids in late pregnancy were analysed by gas chromatography. Associations between personal characteristics and serum levels of organochlorine compounds were analysed by multiple linear regression. Results Participation rate was 82% (325 of 395 women. Serum concentrations of PCB congeners IUPAC no. 28, 52, 101, 105 and 167, and o, p'-DDT and -DDE, p, p'-DDT and -DDD, oxychlordane, and γ- and α-HCH were in many cases below the limit of quantification (LOQ. No statistical analysis of associations with personal characteristics could be performed for these substances. Concentrations of PCB congeners IUPAC no. 118, 138, 153, 156 and 180, HCB, β-HCH, trans-nonachlor and p, p'-DDE increased with increased age and were highest in women sampled early during the 4 year study period. This shows that older women and women sampled early in the study had experienced the highest life-time exposure levels, probably mainly during childhood and adolescence. The importance of early exposures was supported by lower PCB concentrations and higher β-HCH and p, p'-DDE concentrations among women born in non-Nordic countries. Moreover, serum concentrations of certain PCBs and pesticide/metabolites were positively associated with consumption of fatty fish during adolescence, and concentrations of CB 156, CB 180 and p, p'-DDE increased significantly with number of months women had been breast-fed during infancy. Short-term changes in bodily constitution may, however, also influence

  16. 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.

  17. 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.

  18. Steadily translating parabolic dissolution fingers

    CERN Document Server

    Kondratiuk, Paweł

    2015-01-01

    Dissolution fingers (or wormholes) are formed during the dissolution of a porous rock as a result of nonlinear feedbacks between the flow, transport and chemical reactions at pore surfaces. We analyze the shapes and growth velocities of such fingers within the thin-front approximation, in which the reaction is assumed to take place instantaneously with the reactants fully consumed at the dissolution front. We concentrate on the case when the main flow is driven by the constant pressure gradient far from the finger, and the permeability contrast between the inside and the outside of the finger is finite. Using Ivantsov ansatz and conformal transformations we find the family of steadily translating fingers characterized by a parabolic shape. We derive the reactant concentration field and the pressure field inside and outside of the fingers and show that the flow within them is uniform. The advancement velocity of the finger is shown to be inversely proportional to its radius of curvature in the small P\\'{e}clet...

  19. Fabrication, Designing & Performance Analysis of Solar Parabolic Trough

    Directory of Open Access Journals (Sweden)

    Mayur G. Tayade,

    2014-07-01

    Full Text Available A parabolic trough solar collector uses a parabolic cylinder to reflect and concentrate sun radiations towards a receiver tube located at the focus line of the parabolic cylinder. The receiver absorbs the incoming radiations and transforms them into thermal energy, the latter being transported and collected by a fluid medium circulating within the receiver tube.This method of concentrated solar collection has the advantage of high efficiency and low cost, and can be used either for thermal energy collection, for generating electricity or for both, This paper focused on the fabrication and designing of solar parabolic trough, The designing of trough is depend upon the following parameters : Aperture of the concentrator , Inner diameter of absorber tube, Outer diameter of absorber tube, Inner diameter of glass tube, Outer diameter of glass tube, Length of parabolic trough, Concentration ratio, Collector aperture area, Specular reflectivity of concentrator, Glass cover transitivity for solar radiation, Absorber tube emissivity/emissivity, Intercept factor, Emissivity of absorber tube surface and Emissivity of glass. The performance analysis will be based on the Experimental data collection and calculations with reference to: Thermal performance calculations, Overall loss coefficient and heat correlations. Heat transfer coefficient on the inside surface of the absorber tube and Heat transfer coefficient between the absorber tube and the Cover.

  20. Influence of basements, garages, and common hallways on indoor residential volatile organic compound concentrations

    Science.gov (United States)

    Dodson, Robin E.; Levy, Jonathan I.; Spengler, John D.; Shine, James P.; Bennett, Deborah H.

    Concentrations of many volatile organic compounds (VOCs) are often higher inside residences than outdoors as a result of sources or activities within the residences. These sources can be located directly in the living space of the home or in areas associated with the home such as an attached garage, basement, or common apartment hallway. To characterize the contributions from these areas to indoor residential concentrations, VOC concentrations were measured inside, outside, and, if present, in the attached garage, basement, or common hallway of an apartment of 55 residences in the Boston area, most over two seasons, as part of the Boston Exposure Assessment in Microenvironments (BEAM) Study. Of the 55 residences in the study, 11 had attached garages and basements, 24 had only basements, 10 other residences had common apartment hallways, and the remaining 10 were treated as single compartment residences. Concentrations in the garage were up to 5-10 times higher at the median than indoor concentrations for mobile source pollutants including benzene, toluene, ethylbenzene, and xylenes. Basement/indoor concentration ratios were significantly >1 for methylene chloride, ethylbenzene, m, p-xylene, and o-xylene, and summer ratios tended to be higher than winter ratios. Approximately, 20-40% of the indoor concentration for compounds associated with gasoline sources, such as methyl t-butyl ether (MTBE), benzene, toluene, ethylbenzene, and xylenes, can be attributed to an attached garage at the residence, with garages laterally attached to the first floor of the home having a larger impact. At the median, basements contributed to approximately 10-20% of the estimated indoor concentrations. For apartments, approximately 5-10% of the estimated indoor concentrations confer with air from the hallway. Contributions of these secondary zones to concentrations in the living area of a home were calculated using concentration and airflow estimates. Our findings illustrate the potential

  1. [Corrosion resistance of casted titanium by compound treatments in the artificial saliva with different fluoride concentrations].

    Science.gov (United States)

    Wang, Xian-li; Guo, Tian-wen

    2012-09-01

    To study the corrosion resistance of casted titanium by plasma nitriding and TiN-coated compound treatments in the artificial saliva with different fluoride concentrations and to investigate whether compound treatments can increase the corrosion resistance of casted titanium. Potentiodynamic polarization technique was used to depict polarization curve and to measured the current density of corrosion (Icorr) and the electric potential of corrosion (Ecorr) of casted titanium (Group A) and casted titanium by compound treatments (Group B) in the artificial saliva with different fluoride concentrations. After electrochemical experiment, the microstructure was observed by scanning electron microscope (SEM). The Icorrs of Group A and B in the artificial saliva of different fluoride concentrations were (1530.23 ± 340.12), (2290.36 ± 320.10), (4130.52 ± 230.17) nA and (2.62 ± 0.64), (7.37 ± 3.59), (10.76 ± 6.05) nA, respectively. The Ecorrs were (-0.93 ± 0.10), (-0.89 ± 0.21), (-0.57 ± 0.09) V and (-0.21 ± 0.04), (-0.17 ± 0.03), (-0.22 ± 0.03) V, respectively.The Icorrs of Group B were significantly lower (P plasma nitriding and TiN-coated compound treatments can significantly increase the corrosion resistance of casted titanium.

  2. Past and future trends in concentrations of sulphur and nitrogen compounds in the Arctic

    DEFF Research Database (Denmark)

    Hole, Lars R.; Christensen, Jesper H.; Ruoho-Airola, Tuija

    2009-01-01

    Recent trends in nitrogen and sulphur compounds in air and precipitation from a range of Arctic monitoring stations are presented, with seasonal data from the late 70s to 2004 or 2005. Earlier findings of declining sulphur concentrations are confirmed for most stations, while the pattern is less......-2000 is reasonably well reproduced at most stations using an Eulerian, hemispherical model. Results for nitrogen compounds are weaker. Scenario studies show that even if large sulphur emission reductions take place in important source regions in South-East Asia in the coming decades, only small changes in Arctic...

  3. Temporal variation of carbonyl compound concentrations at a semi-rural site in Denmark

    DEFF Research Database (Denmark)

    Christensen, C.S.; Skov, H.; Nielsen, T.

    2000-01-01

    The atmospheric concentrations of formaldehyde, acetaldehyde and acetone were measured by the DNPH-technique at the semi-rural site Lille Valby, Denmark (55 degrees N) between May-July 1995, The average concentrations were observed to be 1.2 ppbv for formaldehyde, 0.8 ppbv for acetaldehyde and 1.......9 ppbv for acetone, For the set of carbonyl compounds, concentrations were found to be highly correlated, though only during daytime, The weak correlations observed during nighttime are believed to be caused by the dry deposition of especially formaldehyde, During periods with low photochemical activity...... of hydrocarbons during long-range transport. Especially, the concentration levels of acetone showed a pronounced seasonal-variation with the highest levels observed during summertime and lowest in winter and spring. The seasonal variation in the concentration levels of formaldehyde and acetaldehyde were small...

  4. Concentration of Umami Compounds in Pork Meat and Cooking Juice with Different Cooking Times and Temperatures.

    Science.gov (United States)

    Rotola-Pukkila, Minna K; Pihlajaviita, Seija T; Kaimainen, Mika T; Hopia, Anu I

    2015-12-01

    This study examined the concentrations of umami compounds in pork loins cooked at 3 different temperatures and 3 different lengths of cooking times. The pork loins were cooked with the sous vide technique. The free amino acids (FAAs), glutamic acid and aspartic acid; the 5'-nucleotides, inosine-5'-monophosphate (IMP) and adenosine-5'-monophosphate (AMP); and corresponding nucleoside inosine of the cooked meat and its released juice were determined by high-performance liquid chromatography. Under the experimental conditions used, the cooking temperature played a more important role than the cooking time in the concentration of the analyzed compounds. The amino acid concentrations in the meat did not remain constant under these experimental conditions. The most notable effect observed was that of the cooking temperature and the higher amino acid concentrations in the released juice of meat cooked at 80 °C compared with 60 and 70 °C. This is most likely due to the heat induced hydrolysis of proteins and peptides releasing water soluble FAAs from the meat into the cooking juice. In this experiment, the cooking time and temperature had no influence on the IMP concentrations observed. However, the AMP concentrations increased with the increasing temperature and time. This suggests that the choice of time and temperature in sous vide cooking affects the nucleotide concentration of pork meat. The Sous vide technique proved to be a good technique to preserve the cooking juice and the results presented here show that cooking juice is rich in umami compounds, which can be used to provide a savory or brothy taste. © 2015 Institute of Food Technologists®

  5. Commercialization of parabolic dish systems

    Science.gov (United States)

    Washom, B.

    1982-01-01

    The impact of recent federal tax and regulatory legislation on the commercialization of parabolic solar reflector technology is assessed. Specific areas in need of technical or economic improvement are noted.

  6. Invariant foliations for parabolic equations

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    It is proved for parabolic equations that under certain conditions the weak (un-)stable manifolds possess invariant foliations, called strongly (un-)stable foliations. The relevant results on center manifolds are generalized to weak hyperbolic manifolds.

  7. The planar parabolic optical antenna.

    Science.gov (United States)

    Schoen, David T; Coenen, Toon; García de Abajo, F Javier; Brongersma, Mark L; Polman, Albert

    2013-01-09

    One of the simplest and most common structures used for directing light in macroscale applications is the parabolic reflector. Parabolic reflectors are ubiquitous in many technologies, from satellite dishes to hand-held flashlights. Today, there is a growing interest in the use of ultracompact metallic structures for manipulating light on the wavelength scale. Significant progress has been made in scaling radiowave antennas to the nanoscale for operation in the visible range, but similar scaling of parabolic reflectors employing ray-optics concepts has not yet been accomplished because of the difficulty in fabricating nanoscale three-dimensional surfaces. Here, we demonstrate that plasmon physics can be employed to realize a resonant elliptical cavity functioning as an essentially planar nanometallic structure that serves as a broadband unidirectional parabolic antenna at optical frequencies.

  8. Characterizing reduced sulfur compounds and non-methane volatile organic compounds emissions from a swine concentrated animal feeding operation

    Science.gov (United States)

    Rumsey, Ian Cooper

    Reduced sulfur compounds (RSCs) and non-methane volatile organic compounds (NMVOCs) emissions from concentrated animal feeding operations (CAFOs) have become a potential environmental and human health concern. Both RSCs and NMVOCs contribute to odor. In addition, RSCs also have the potential to form fine particulate matter (PMfine) and NMVOCs the potential to form ozone. Measurements of RSCs and NMVOCs emissions were made from both an anaerobic lagoon and barn at a swine CAFO in North Carolina. Emission measurements were made over all four seasonal periods. In each seasonal period, measurements were made from both the anaerobic lagoon and barn for ˜1 week. RSC and NMVOCs samples were collected using passivated canisters. Nine to eleven canister samples were taken from both the lagoon and barn over each sampling period. The canisters were analyzed ex-situ using gas chromatography flame ionization detection (GC-FID). Hydrogen sulfide (H2S) measurements were made in-situ using a pulsed fluorescence H2S/SO2 analyzer. During sampling, measurements of meteorological and physiochemical parameters were made. H2S had the largest RSC flux, with an overall average lagoon flux of 1.33 mug m-2 min-1. The two main RSCs identified by the GC-FID, dimethyl sulfide (DMS) and dimethyl disulfide (DMDS), had overall average lagoon fluxes an order of magnitude lower, 0.12 and 0.09 mug m-2 min-1, respectively. Twelve significant NMVOCs were identified in lagoon samples (ethanol, 2-ethyl-1-hexanol, methanol, acetaldehyde, decanal, heptanal, hexanal, nonanal, octanal, acetone, methyl ethyl ketone, and 4-methylphenol). The overall average fluxes for these NMVOCs, ranged from 0.08 mug m-2 min-1 (4-methylphenol) to 2.11 mug m-2 min-1 (acetone). Seasonal H2S barn concentrations ranged from 72-631 ppb. DMS and DMDS seasonal concentrations were 2-3 orders of magnitude lower. There were six significant NMVOCs identified in barn samples (methanol, ethanol, acetone 2-3 butanedione, acetaldehyde

  9. Parabolic sheaves on logarithmic schemes

    OpenAIRE

    Borne, Niels; Vistoli, Angelo

    2010-01-01

    We show how the natural context for the definition of parabolic sheaves on a scheme is that of logarithmic geometry. The key point is a reformulation of the concept of logarithmic structure in the language of symmetric monoidal categories, which might be of independent interest. Our main result states that parabolic sheaves can be interpreted as quasi-coherent sheaves on certain stacks of roots.

  10. Parabolic metamaterials and Dirac bridges

    Science.gov (United States)

    Colquitt, D. J.; Movchan, N. V.; Movchan, A. B.

    2016-10-01

    A new class of multi-scale structures, referred to as `parabolic metamaterials' is introduced and studied in this paper. For an elastic two-dimensional triangular lattice, we identify dynamic regimes, which corresponds to so-called `Dirac Bridges' on the dispersion surfaces. Such regimes lead to a highly localised and focussed unidirectional beam when the lattice is excited. We also show that the flexural rigidities of elastic ligaments are essential in establishing the `parabolic metamaterial' regimes.

  11. 一种槽式太阳能聚光器安装质量的检测方法%A Method for the Detection of the Installation Quality of a Parabolic Trough Solar Concentrators

    Institute of Scientific and Technical Information of China (English)

    朱小炜; 符伟; 张玉霞; 王博威

    2015-01-01

    为有效提高抛物槽式太阳能聚光器的聚光效率,需要对聚光器各个反射镜的安装位置进行检测和校准。本文采用Marposs公司研发的VISField系统,利用吸热管反射成像法,根据相机与聚光器的相对位置关系,推导吸热管在子镜中的成像位置,进而完成聚光器各子镜位置误差的调整。以全站仪为第三方工具,利用外部靶点信息对吸热管进行位置调整以及完成相机姿态的动态校准。利用本文提出的方法进行实验,调整后各反射镜的平均截断因子近似为1,说明吸热管在子镜中的实际成像位置与理论成像位置近似重合,验证了检测方法的正确性和可行性。%To effectively raise the concentration efficiency of the parabolic trough solar concentrator, the detection and calibration of the installation position for each concentrator mirror are needed. The VISField system developed by Marposs Company is adopted in this paper. According to the relative position between cameras and concentrator, the image position of the endothermic tube in the sub mirror is derived with the refiection imaging method, and then the adjustment of sub mirrors’ position error is completed. With total station instrument as the auxiliary tool, the position adjustments of the heat absorbing tube and the dynamic calibration of the camera pose are completed with the external target information. The experiment is conducted with the method proposed in this paper. With the intercept factor of each mirror closing to 1 after adjustment, this experiment indicates that the actual imaging location and theory position of the endothermic tube in sub mirrors are approximately coincided, which verifies the correctness and feasibility of the method.

  12. Evaluation of cetacean exposure to organotin compounds in Brazilian waters through hepatic total tin concentrations

    Energy Technology Data Exchange (ETDEWEB)

    Dorneles, Paulo R. [Laboratorio de Radioisotopos Eduardo Penna Franca, Instituto de Biofisica Carlos Chagas Filho, CCS, Universidade Federal do Rio de Janeiro (Brazil); Laboratorio de Mamiferos Aquaticos (MAQUA), Faculdade de Oceanografia, Universidade do Estado do Rio de Janeiro (Brazil)], E-mail: dornelespr@gmail.com; Lailson-Brito, Jose [Laboratorio de Radioisotopos Eduardo Penna Franca, Instituto de Biofisica Carlos Chagas Filho, CCS, Universidade Federal do Rio de Janeiro (Brazil); Laboratorio de Mamiferos Aquaticos (MAQUA), Faculdade de Oceanografia, Universidade do Estado do Rio de Janeiro (Brazil)], E-mail: lailson@uerj.br; Fernandez, Marcos A.S. [Laboratorio de Oceanografia Quimica, Faculdade de Oceanografia, Universidade do Estado do Rio de Janeiro (Brazil)], E-mail: hallfz@uerj.br; Vidal, Lara G. [Laboratorio de Mamiferos Aquaticos (MAQUA), Faculdade de Oceanografia, Universidade do Estado do Rio de Janeiro (Brazil)], E-mail: vidallara@yahoo.com.br; Barbosa, Lupercio A. [Instituto ORCA, Vila Velha, ES (Brazil)], E-mail: lupercio@orca.org.br; Azevedo, Alexandre F. [Laboratorio de Mamiferos Aquaticos (MAQUA), Faculdade de Oceanografia, Universidade do Estado do Rio de Janeiro (Brazil)], E-mail: alexandre.maqua@gmail.com; Fragoso, Ana B.L. [Laboratorio de Mamiferos Aquaticos (MAQUA), Faculdade de Oceanografia, Universidade do Estado do Rio de Janeiro (Brazil)], E-mail: abfragoso@gmail.com; Torres, Joao P.M. [Laboratorio de Radioisotopos Eduardo Penna Franca, Instituto de Biofisica Carlos Chagas Filho, CCS, Universidade Federal do Rio de Janeiro (Brazil)], E-mail: jptorres@biof.ufrj.br; Malm, Olaf [Laboratorio de Radioisotopos Eduardo Penna Franca, Instituto de Biofisica Carlos Chagas Filho, CCS, Universidade Federal do Rio de Janeiro (Brazil)], E-mail: olaf@biof.ufrj.br

    2008-12-15

    In Brazil, there is no restriction to the use of organotins (OTs). Previous investigations have shown that hepatic {sigma}Sn in cetaceans is predominantly organic. Hepatic {sigma}Sn concentrations were determined by GFAAS in 67 cetaceans (13 species) that stranded on Rio de Janeiro (RJ) and Espirito Santo (ES) states. Concentrations (in ng/g wet wt.) of marine tucuxis (n = 20) from the highly contaminated Guanabara Bay (in RJ) varied from 1703 to 9638. Concentrations of three marine tucuxi foetuses and one newborn calf (all from Guanabara Bay) varied between 431 and 2107. Contrastingly, the maximum level among 19 oceanic dolphins was 346, and 15 out of these 19 specimens presented concentrations below detection limit. The levels of Sn in six marine tucuxis from a less contaminated area (ES) varied from below detection limit to 744. Comparing to the literature, coastal cetaceans from Brazil appear to be highly exposed to OTs. - Cetaceans from Brazil are highly exposed to organotin compounds.

  13. Design and Testing of a Shell-Encapsulated Solar Collector with the Compound Surface Concentrators

    Directory of Open Access Journals (Sweden)

    Hongfei Zheng

    2015-01-01

    Full Text Available This paper presents design and testing of a shell-encapsulated solar collector which can be used in north area of China for wall-amounting installation. The designed solar collector is based on the combination of a novel compound curved surface concentrator and an aluminum concentric solar receiver, which is contained in a glass evacuated-tube. As there is no perforative joint between the double-skin glass evacuated-tube and the aluminum concentric solar receiver, the difficulty of vacuum keeping for a glass-metal joint is avoided. The cavity shell provides an additional thermal insulation to reduce heat loss of the designed solar collector. The working principle of the compound curved surface concentrator is described. The ray-tracing results are given to show the effect of deviation angle of the concentrator on its optical efficiency, hence determining its maximum acceptance angle. A prototype of the designed solar collector has been constructed and tested under the sunny winter weather condition. The experimental results indicate that the hot water temperature higher than 80°C with a daily average efficiency of about 45~50% has been achieved at the average ambient temperature below 0°C, so the designed solar collector can produce hot water at a useful temperature in winter.

  14. Boundary layer concentrations and landscape scale emissions of volatile organic compounds in early spring

    Directory of Open Access Journals (Sweden)

    S. Haapanala

    2007-01-01

    Full Text Available Boundary layer concentrations of several volatile organic compounds (VOC were measured during two campaigns in springs of 2003 and 2006. The measurements were conducted over boreal landscapes near SMEAR II measurement station in Hyytiälä, Southern Finland. In 2003 the measuremens were performed using a light aircraft and in 2006 using a hot air balloon. Isoprene concentrations were low, usually below detection limit. This can be explained by low biogenic production due to cold weather, phenological stage of the isoprene emitting plants, and snow cover. Monoterpenes were observed frequently. The average total monoterpene concentration in the boundary layer was 33 pptv. Many anthropogenic compounds such as benzene, xylene and toluene, were observed in high amounts. Ecosystem scale surface emissions were estimated using a simple mixed box budget methodology. Total monoterpene emissions varied up to 80 μg m−2 h−1, α-pinene contributing typically more than two thirds of that. These emissions were somewhat higher that those calculated using emission algorithm. The highest emissions of anthropogenic compounds were those of p/m xylene.

  15. Parabolic aircraft solidification experiments

    Science.gov (United States)

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

    1996-01-01

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

  16. Concentration and distribution of dioxins and related compounds in various human organs

    Energy Technology Data Exchange (ETDEWEB)

    Iida, T.; Hirakawa, H.; Hori, T.; Tobiishi, K.; Matsueda, T. [Fukuoka Inst. of Health and Environmental Sciences, Dazaifu, Fukuoka (Japan); Todaka, T. [Japan Food Hygiene Association, Tokyo (Japan); Watanabe, S. [Tokyo Univ. of Agriculture, Tokyo (Japan); Yamada, T. [Keio Univ. School of Medicine, Tokyo (Japan)

    2004-09-15

    Polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs) and non-ortho coplanar polychlorinated biphenyls (Non-Co-PCBs) and mono-ortho coplanar polychlorinated biphenyls (Mono-Co-PCBs) accumulate in the human body due to their highly lipophilic properties. In recent years, there has been some concern about the potential health effects of dioxins and related chemicals for the general population of humans. Although there exists an enormous amount of data on this subject, most of it is from breast milk and blood, due to ease of collection; information concerning concentrations and distribution in various human organs hardly exists. Therefore, new data concerning various human tissues is required to evaluate the pathophysiological significance of dioxins and related compounds in humans. The aim of this study was to investigate the concentration levels and distribution of dioxins and related compounds in various human organ tissues. We previously reported on the concentration levels in the human liver and adipose tissues from 28 donors. In this paper, we determined the concentrations of dioxin-like isomers in 8 organs, including blood, lungs, liver, bile, spleen, pancreas, kidney and mesentery fat from 20 donors.

  17. Relationship between the concentration of volatile sulphur compound and periodontal disease severity in Nigerian young adults.

    Science.gov (United States)

    Ehizele, Adebola O; Ojehanon, Patrick I

    2013-05-01

    The aim of this study was to determine the relationship between the concentration of volatile sulphur compounds (VSC) in mouth air and the severity of periodontal diseases in young adults. A total of 400 subjects were studied. Estimation of periodontal disease severity was done using the basic periodontal examination (BPE) and the baseline measurement of the concentration of VSC in the mouth air of the subjects was done objectively using the Halimeter(®). The mean concentration of VSC for the group with BPE code 0 was 91.0 ± 5.9 parts per billion (ppb), 156.4 ± 9.4 ppb for BPE code 1, 275.2 ± 38.5 ppb for BPE code 2, 353.5 ± 72.3 ppb for BPE code 3, and 587.0 ± 2.1 ppb for BPE code 4 (P = 0.001). Majority (79.0%) of the subjects with BPE code 0 had concentration of VSC ppb. Sixty-two (54.9%) with BPE code 1 had concentration of VSC ppb, 34% with BPE code 2 had concentration of VSC ppb and 42.9% with BPE code 3 had concentration of VSC ppb. Only 6.5% of the subjects with BPE code 0 had VSC concentration >250 ppb, whereas all (100%) of those with BPE code 4 had VSC concentration >250 ppb (P = 0.001). It was concluded that a relationship exists between the periodontal pocket depth and the concentration of VCS in mouth air of young adults.

  18. Diurnal variability of polycyclic aromatic compound (PAC) concentrations: Relationship with meteorological conditions and inferred sources

    Science.gov (United States)

    Alam, Mohammed S.; Keyte, Ian J.; Yin, Jianxin; Stark, Christopher; Jones, Alan M.; Harrison, Roy M.

    2015-12-01

    Polycyclic aromatic hydrocarbons (PAH) and their nitro and oxy derivatives have been sampled every three hours over one week in winter at two sites in Birmingham UK. One site is heavily influenced by road traffic and is close to residential dwellings, while the other site is a background urban location at some distance from both sources of emission. The time series of concentrations has been examined along with the ratio of concentrations between the two sampling sites. A comparison of averaged diurnal profiles has shown different patterns of behaviour which has been investigated through calculating ratios of concentration at 18:00-21:00 h relative to that at 06:00-09:00 h. This allows identification of those compounds with a strong contribution to a traffic-related maximum at 06:00-09:00 h which are predominantly the low molecular weight PAHs, together with a substantial group of quinones and nitro-PAHs. Changes in partitioning between vapour and particulate forms are unlikely to influence the ratio as the mean temperature at both times was almost identical. Most compounds show an appreciable increase in concentrations in the evening which is attributed to residential heating emissions. Compounds dominated by this source show high ratios of 18:00-21:00 concentrations relative to 06:00-09:00 concentrations and include higher molecular weight PAH and a substantial group of both quinones and nitro-PAH. The behaviour of retene, normally taken as an indicator of biomass burning, is suggestive of wood smoke only being one contributor to the evening peak in PAH and their derivatives, with coal combustion presumably being the other main contributor. Variations of PAH concentrations with wind speed show a dilution behaviour consistent with other primary pollutants, and high concentrations of a range of air pollutants were observed in an episode of low temperatures and low wind speeds towards the end of the overall sampling period consistent with poor local dispersion

  19. Measurement and Comparison of Organic Compound Concentrations in Plasma, Whole Blood, and Dried Blood Spot Samples.

    Science.gov (United States)

    Batterman, Stuart A; Chernyak, Sergey; Su, Feng-Chiao

    2016-01-01

    The preferred sampling medium for measuring human exposures of persistent organic compounds (POPs) is blood, and relevant sample types include whole blood, plasma, and dried blood spots (DBS). Because information regarding the performance and comparability of measurements across these sample types is limited, it is difficult to compare across studies. This study evaluates the performance of POP measurements in plasma, whole blood and DBS, and presents the distribution coefficients needed to convert concentrations among the three sample types. Blood samples were collected from adult volunteers, along with demographic and smoking information, and analyzed by GC/MS for organochlorine pesticides (OCPs), chlorinated hydrocarbons (CHCs), polychlorinated biphenyls (PCBs), and brominated diphenyl ethers (PBDEs). Regression models were used to evaluate the relationships between the sample types and possible effects of personal covariates. Distribution coefficients also were calculated using physically-based models. Across all compounds, concentrations in plasma were consistently the highest; concentrations in whole blood and DBS samples were comparable. Distribution coefficients for plasma to whole blood concentrations ranged from 1.74 to 2.26 for pesticides/CHCs, averaged 1.69 ± 0.06 for the PCBs, and averaged 1.65 ± 0.03 for the PBDEs. Regression models closely fit most chemicals (R (2) > 0.80), and whole blood and DBS samples generally showed very good agreement. Distribution coefficients estimated using biologically-based models were near one and did not explain the observed distribution. Among the study population, median concentrations of several pesticides/CHCs and PBDEs exceeded levels reported in the 2007-2008 National Health and Nutrition Examination Survey, while levels of other OCPs and PBDEs were comparable or lower. Race and smoking status appeared to slightly affect plasma/blood concentration ratios for several POPs. The experimentally

  20. Measurement and Comparison of Organic Compound Concentrations in Plasma, Whole Blood and Dried Blood Spot Samples

    Directory of Open Access Journals (Sweden)

    Stuart A Batterman

    2016-04-01

    Full Text Available The preferred sampling medium for measuring human exposures of persistent organic compounds (POPs is blood, and relevant sample types include whole blood, plasma, and dried blood spots (DBS. Because information regarding the performance and comparability of measurements across these sample types is limited, it is difficult to compare across studies. This study evaluates the performance of POP measurements in plasma, whole blood and DBS, and presents the distribution coefficients needed to convert concentrations among the three sample types. Blood samples were collected from adult volunteers, along with demographic and smoking information, and analyzed by GC/MS for organochlorine pesticides (OCPs, chlorinated hydrocarbons (CHCs, polychlorinated biphenyls (PCBs, and brominated diphenyl ethers (PBDEs. Regression models were used to evaluate the relationships between the sample types and possible effects of personal covariates. Distribution coefficients also were calculated using physically-based models.Across all compounds, concentrations in plasma were consistently the highest; concentrations in whole blood and DBS samples were comparable. Distribution coefficients for plasma to whole blood concentrations ranged from 1.74 to 2.26 for pesticides/CHCs, averaged 1.69 ± 0.06 for the PCBs, and averaged 1.65 ± 0.03 for the PBDEs. Regression models closely fit most chemicals (R2 > 0.80, and whole blood and DBS samples generally showed very good agreement. Distribution coefficients estimated using biologically-based models were near one and did not explain the observed distribution. Among the study population, median concentrations of several pesticides/CHCs and PBDEs exceeded levels reported in the 2007-2008 National Health and Nutrition Examination Survey, while levels of other OCPs and PBDEs were comparable or lower. Race and smoking status appeared to slightly affect plasma/blood concentration ratios for several POPs. The experimentally

  1. Engineering parabolic beams with dynamic intensity profiles.

    Science.gov (United States)

    Ruelas, Adrian; Lopez-Aguayo, Servando; Gutiérrez-Vega, Julio C

    2013-08-01

    We present optical fields formed by superposing nondiffracting parabolic beams with distinct longitudinal wave-vector components, generating light profiles that display intensity fluxes following parabolic paths in the transverse plane. Their propagation dynamics vary depending on the physical mechanism originating interference, where the possibilities include constructive and destructive interference between traveling parabolic beams, interference between stationary parabolic modes, and combinations of these. The dark parabolic region exhibited by parabolic beams permits a straightforward superposition of intensity fluxes, allowing formation of a variety of profiles, which can exhibit circular, elliptic, and other symmetries.

  2. Snowpack concentrations and estimated fluxes of volatile organic compounds in a boreal forest

    Directory of Open Access Journals (Sweden)

    H. Aaltonen

    2012-06-01

    Full Text Available Soil provides an important source of volatile organic compounds (VOCs to atmosphere, but in boreal forests these fluxes and their seasonal variations have not been characterized in detail. Especially wintertime fluxes are almost completely unstudied. In this study, we measured the VOC concentrations inside the snowpack in a boreal Scots pine (Pinus sylvestris L. forest in southern Finland, using adsorbent tubes and air samplers installed permanently in the snow profile. Based on the VOC concentrations at three heights inside the snowpack, we estimated the fluxes of these gases. We measured 20 VOCs from the snowpack, monoterpenes being the most abundant group with concentrations varying from 0.11 to 16 μg m−3. Sesquiterpenes and oxygen-containing monoterpenes were also detected. Inside the pristine snowpack, the concentrations of terpenoids decreased from soil surface towards the surface of the snow, suggesting soil as the source for terpenoids. Forest damages (i.e. broken treetops and branches, fallen trees resulting from heavy snow loading during the measurement period increased the terpenoid concentrations dramatically, especially in the upper part of the snowpack. The results show that soil processes are active and efficient VOC sources also during winter, and that natural or human disturbance can increase forest floor VOC concentrations substantially. Our results stress the importance of soil as a source of VOCs during the season when other biological sources, such as plants, have lower activity.

  3. Relationship between the concentration of volatile sulphur compound and periodontal disease severity in Nigerian young adults

    Directory of Open Access Journals (Sweden)

    Adebola O Ehizele

    2013-01-01

    Full Text Available Background: The aim of this study was to determine the relationship between the concentration of volatile sulphur compounds (VSC in mouth air and the severity of periodontal diseases in young adults. Materials and Methods: A total of 400 subjects were studied. Estimation of periodontal disease severity was done using the basic periodontal examination (BPE and the baseline measurement of the concentration of VSC in the mouth air of the subjects was done objectively using the Halimeter®. Result: The mean concentration of VSC for the group with BPE code 0 was 91.0 ± 5.9 parts per billion (ppb, 156.4 ± 9.4 ppb for BPE code 1, 275.2 ± 38.5 ppb for BPE code 2, 353.5 ± 72.3 ppb for BPE code 3, and 587.0 ± 2.1 ppb for BPE code 4 ( P = 0.001. Majority (79.0% of the subjects with BPE code 0 had concentration of VSC 250 ppb, whereas all (100% of those with BPE code 4 had VSC concentration >250 ppb ( P = 0.001. Conclusion: It was concluded that a relationship exists between the periodontal pocket depth and the concentration of VCS in mouth air of young adults.

  4. Snowpack concentrations and estimated fluxes of volatile organic compounds in a boreal forest

    Directory of Open Access Journals (Sweden)

    H. Aaltonen

    2012-01-01

    Full Text Available Soil forms an important source for volatile organic compounds (VOCs, but in boreal forests these fluxes and their seasonal variations have not been characterized in detail, especially wintertime fluxes, which are almost completely unstudied. In this study, we measured the VOC concentrations inside a snowpack in a boreal Scots pine (Pinus sylvestris L. forest in southern Finland, using adsorbent tubes and air samplers installed permanently in the snow profile. Based on the VOC concentrations at three heights inside the snowpack, we estimated the fluxes of these gases. We measured 20 VOCs from the snowpack, monoterpenes being the most abundant group with concentrations varying from 0.11 to 16 μg m−3. Sesquiterpenes and oxygen-containing monoterpenes were also detected. Inside the pristine snowpack, the concentrations of terpenoids decreased from the soil surface towards the snow surface, suggesting soil as being the source for terpenoids. Forest damages resulting from heavy snow loading during the measurement period increased the terpenoid concentrations dramatically, especially in the upper part of the snowpack. The results show that soil processes are also active and efficient VOC sources during winter and that natural or human disturbance can increase forest floor VOC concentrations substantially. Our results stress the importance of soil as a source of VOCs during the season when other biological sources, basically plants, have lower activity.

  5. Characterization, Concentrations and Emission Rates of Volatile Organic Compounds from Two Major Landfill Sites in Kuwait

    Directory of Open Access Journals (Sweden)

    Mohammad AlAhmad

    2012-01-01

    Full Text Available Problem statement: The emission of pollutants from landfill sites in Kuwait is of major concern due to the associated adverse environmental and health impacts. There are 18 landfill sites in Kuwait which are contributing to the emission of atmospheric pollutants including; methane, carbon dioxide and Volatile Organic Compounds (VOCs. Approach: Determine the concentration and composition of VOCs in LFG emissions from two major landfill sites in Kuwait and to investigate the influence of the "In-Situ Aerobic Stabilization" on the reduction of VOCs emission. VOCs samples were collected during an intensive, short-term field sampling campaign conducted in 2010 where 50 individual volatile organic compounds were identified and quantified in landfill gas samples collected from the two landfill sites and the Project Area. Results: The concentration levels of VOCs were found to be significantly different within the same landfill site; however, the average total VOCs emissions were comparable between the two landfill sites. Concentration of total VOCs (i.e., sum of 50 compounds in LFG emissions varied between 9.4-67.2 ppm in Jleeb Al-Shuyoukh landfill site and from 15.4-57.7 ppm in Al-Qurain landfill site. Annual emissions of the well-known five VOCs (i.e., benzene, toluene, ethylbenzene, m-, o- and p-xylenes and styrene were also computed for each vent pipe from Jleeb Al-Shuyoukh landfill using the measured average concentrations and LFG flow rates. The results, if calculated in terms of the average ΣBTEX+S quantity emitted per vent pipe per year, showed that the magnitude of ΣBTEX+S emissions ranged between 0.108 -11.686 g y−1. Conclusion: The results of this pilot project demonstrated that the “in-situ aerobic stabilization method” applied on old solid waste deposits in the project area of Jleeb Al-Shuyoukh landfill can significantly reduce the average VOCs concentration in LFG emissions from high-productivity wells in the project

  6. Seasonal trends of dry and bulk concentration of nitrogen compounds over a rain forest in Ghana

    Directory of Open Access Journals (Sweden)

    F. Fattore

    2013-09-01

    Full Text Available African tropical forests of the equatorial belt might receive significant input of extra nitrogen derived from biomass burning occurring in the north savanna belt and transported equator wards by NE winds. In order to test this hypothesis an experiment was set up in a tropical rain forest in the National park of Ankasa (Ghana aiming at: quantifying magnitude and seasonal variability of concentrations of N compounds, present as gas and aerosol (dry nitrogen or in the rainfall (bulk nitrogen, over the studied forest; relating their seasonal variability to trends of local and regional winds and rainfall and to variations of fire events in the region. Three Delta systems, implemented for monthly measurements of NO2, were mounted over a tower at 45 m height, 20 m above forest canopy to sample gas (NH3, NO2, HNO3, HCl, SO2 and aerosol (NH4+, NO3−, and several ions, together with three tanks for bulk rainfall collection (to analyze NH4+, NO3− and ion concentration. The tower was provided with a sonic anemometer to estimate local wind data. The experiment started in October 2011 and data up to October 2012 are presented. To interpret the observed seasonal trends of measured compounds, local and regional meteo data and regional satellite fire data were analyzed. The concentration of N compounds significantly increased from December to April, during the drier period, peaking in December-February when North Eastern winds (Harmattan were moving dry air masses over the West central African region and the inter tropical convergence zone (ITCZ was at its minimum latitude over the equator. This period also coincided with peaks of fire in the whole region. On the contrary, N concentration in gas, aerosol and rain decreased from May to October when prevalent winds arrived from the sea (South-East, during the Monsoon period. Both ionic compositions of rain and analysis of local wind direction showed a significant and continuous presence of see-breeze at site

  7. Deviations from sorption linearity on soils of polar and nonpolar organic compounds at low relative concentrations

    Science.gov (United States)

    Chiou, C.T.; Kile, D.E.

    1998-01-01

    A series of single-solute and binary-solute sorption data have been obtained on representative samples of polar compounds (substituted ureas and phenolic compounds) and of nonpolar compounds (e.g., EDB and TCE) on a peat soil and a mineral (Woodburn) soil; the data extend to low relative solute concentrations (C(e)/S(w)). At relatively low C(e)/S(w), both the nonpolar and the polar solutes exhibit nonlinear sorption. The sorption nonlinearity approaches apparent saturation at about C(e)/S(w) = 0.010-0.015 for the nonpolar solutes and at about C(e)/S(w) = 0.10-0.13 for the polar solutes; above these C(e)/S(w) regions, the isotherms are practically linear. The nonlinear sorption capacities are greater for polar solutes than for nonpolar solutes and the peat soil shows a greater effect than the Woodburn soil. The small nonlinear sorption capacity for a nonpolar solute is suppressed indiscriminately by either a nonpolar or a polar cosolute at relatively low C(e)/S(w) of the cosolute. By contrast, the abilities of different cosolutes to suppress the nonlinear capacity of a nominal polar solute differ drastically. For polar solutes, a nonpolar cosolute exhibits a limited suppression even at high cosolute C(e)/S(w); effective suppression occurs when the cosolute is relatively polar and at various C(e)/S(w). These differences suggest that more than a single mechanism is required to account for the nonlinear sorption of both nonpolar and polar compounds at low C(e)/S(w). Mechanistic processes consistent with these observations and with soil surface areas are discussed along with other suggested models. Some important consequences of the nonlinear competitive sorption to the behavior of contaminants in natural systems are discussed.A number of conceptual models was postulated to account for the nonlinear solute sorption on soils of significant soil organic matter. A series of single-solute and binary-route sorption data was obtained representing samples of polar compounds of

  8. Shenandoah parabolic dish solar collector

    Energy Technology Data Exchange (ETDEWEB)

    Kinoshita, G.S.

    1985-01-01

    The objectives of the Shenandoah, Georgia, Solar Total Energy System are to design, construct, test, and operate a solar energy system to obtain experience with large-scale hardware systems for future applications. This report describes the initial design and testing activities conducted to select and develop a collector that would serve the need of such a solar total energy system. The parabolic dish was selected as the collector most likely to maximize energy collection as required by this specific site. The fabrication, testing, and installation of the parabolic dish collector incorporating improvements identified during the development testing phase are described.

  9. Shenandoah parabolic dish solar collector

    Energy Technology Data Exchange (ETDEWEB)

    Kinoshita, G.S.

    1985-01-01

    The objectives of the Shenandoah, Georgia, Solar Total Energy System are to design, construct, test, and operate a solar energy system to obtain experience with large-scale hardware systems for future applications. This report describes the initial design and testing activities conducted to select and develop a collector that would serve the need of such a solar total energy system. The parabolic dish was selected as the collector most likely to maximize energy collection as required by this specific site. The fabrication, testing, and installation of the parabolic dish collector incorporating improvements identified during the development testing phase are described.

  10. OPTIMAL CONTROL PROBLEM FOR PARABOLIC VARIATIONAL INEQUALITIES

    Institute of Scientific and Technical Information of China (English)

    汪更生

    2001-01-01

    This paper deals with the optimal control problems of systems governed by a parabolic variational inequality coupled with a semilinear parabolic differential equations.The maximum principle and some kind of approximate controllability are studied.

  11. Seasonal cycles of biogenic volatile organic compound fluxes and concentrations in a California citrus orchard

    Science.gov (United States)

    Fares, S.; Park, J.-H.; Gentner, D. R.; Weber, R.; Ormeño, E.; Karlik, J.; Goldstein, A. H.

    2012-10-01

    Orange trees are widely cultivated in Mediterranean climatic regions where they are an important agricultural crop. Citrus have been characterized as emitters of volatile organic compounds (VOC) in chamber studies under controlled environmental conditions, but an extensive characterization at field scale has never been performed using modern measurement methods, and is particularly needed considering the complex interactions between the orchards and the polluted atmosphere in which Citrus is often cultivated. For one year, in a Valencia orange orchard in Exeter, California, we measured fluxes using PTRMS (Proton Transfer Reaction Mass Spectrometer) and eddy covariance for the most abundant VOC typically emitted from citrus vegetation: methanol, acetone, and isoprenoids. Concentration gradients of additional oxygenated and aromatic compounds from the ground level to above the canopy were also measured. In order to characterize concentrations of speciated biogenic VOC (BVOC) in leaves, we analyzed leaf content by GC-MS (Gas Chromatography - Mass Spectrometery) regularly throughout the year. We also characterized in more detail concentrations of speciated BVOC in the air above the orchard by in-situ GC-MS during a few weeks in spring flowering and summer periods. Here we report concentrations and fluxes of the main VOC species emitted by the orchard, discuss how fluxes measured in the field relate to previous studies made with plant enclosures, and describe how VOC content in leaves and emissions change during the year in response to phenological and environmental parameters. The orchard was a source of monoterpenes and oxygenated VOC. The highest emissions were observed during the springtime flowering period, with mid-day fluxes above 2 nmol m-2 s-1 for methanol and up to 1 nmol m-2 s-1 for acetone and monoterpenes. During hot summer days emissions were not as high as we expected considering the known dependence of biogenic emissions on temperature. We provide

  12. Performance Simulation Comparison for Parabolic Trough Solar Collectors in China

    Directory of Open Access Journals (Sweden)

    Jinping Wang

    2016-01-01

    Full Text Available Parabolic trough systems are the most used concentrated solar power technology. The operating performance and optical efficiency of the parabolic trough solar collectors (PTCs are different in different regions and different seasons. To determine the optimum design and operation of the parabolic trough solar collector throughout the year, an accurate estimation of the daily performance is needed. In this study, a mathematical model for the optical efficiency of the parabolic trough solar collector was established and three typical regions of solar thermal utilization in China were selected. The performance characteristics of cosine effect, shadowing effect, end loss effect, and optical efficiency were calculated and simulated during a whole year in these three areas by using the mathematical model. The simulation results show that the optical efficiency of PTCs changes from 0.4 to 0.8 in a whole year. The highest optical efficiency of PTCs is in June and the lowest is in December. The optical efficiency of PTCs is mainly influenced by the solar incidence angle. The model is validated by comparing the test results in parabolic trough power plant, with relative error range of 1% to about 5%.

  13. Self-similar parabolic plasmonic beams.

    Science.gov (United States)

    Davoyan, Arthur R; Turitsyn, Sergei K; Kivshar, Yuri S

    2013-02-15

    We demonstrate that an interplay between diffraction and defocusing nonlinearity can support stable self-similar plasmonic waves with a parabolic profile. Simplicity of a parabolic shape combined with the corresponding parabolic spatial phase distribution creates opportunities for controllable manipulation of plasmons through a combined action of diffraction and nonlinearity.

  14. Estradiol and endocrine disrupting compounds adversely affect development of sea urchin embryos at environmentally relevant concentrations.

    Science.gov (United States)

    Roepke, Troy A; Snyder, Mark J; Cherr, Gary N

    2005-01-26

    Environmental endocrine disrupting compounds (EDCs) are a wide variety of chemicals that typically exert effects, either directly or indirectly, through receptor-mediated processes, thus mimicking endogenous hormones and/or inhibiting normal hormone activities and metabolism. Little is known about the effects of EDCs on echinoderm physiology, reproduction and development. We exposed developing sea urchin embryos (Strongylocentrotus purpuratus and Lytechinus anamesus) to two known EDCs (4-octylphenol (OCT), bisphenol A (BisA)) and to natural and synthetic reproductive hormones (17beta-estradiol (E2), estrone (E1), estriol (E3), progesterone (P4) and 17alpha-ethynylestradiol (EE2)). In addition, we studied two non-estrogenic EDCs, tributyltin (TBT) and o,p-DDD. Successful development to the pluteus larval stage (96 h post-fertilization) was used to define EDC concentration-response relationships. The order of compound potency based on EC50 values for a reduction in normal development was as follows: TBT(L. anamesus)>OCT>TBT(S. purpuratus)>E2>EE2>DDD>BisA>P4>E1>E3. The effect of TBT was pronounced even at concentrations substantially lower than those commonly reported in heavily contaminated areas, but the response was significantly different in the two model species. Sea urchin embryos were generally more sensitive to estrogenic EDCs and TBT than most other invertebrate larvae. Stage-specific exposure experiments were conducted to determine the most sensitive developmental periods using blastula, gastrula and post-gastrula (pluteus) stages. The stage most sensitive to E2, OCT and TBT was the blastula stage with less overall sensitivity in the gastrula stage, regardless of concentration. Selective estrogen receptor modulators (SERMs) were added to the experiments individually and in combination with estrogenic EDCs to interfere with potential receptor-mediated actions. Tamoxifen, a partial ER agonist, alone inhibited development at concentrations as low as 0.02 ng

  15. Concentrations and flux measurements of volatile organic compounds (VOC) in boreal forest soil

    Science.gov (United States)

    Mäki, Mari; Aaltonen, Hermanni; Heinonsalo, Jussi; Hellén, Heidi; Pumpanen, Jukka; Bäck, Jaana

    2017-04-01

    Volatile organic compounds (VOC) impact soil processes as VOCs transmit signals between roots and rhizosphere (Ditengou et al., 2015), VOCs can regulate microbial activity (Asensio et al., 2012), and VOCs can also promote root growth (Hung et al., 2012). Belowground concentrations of VOCs have not been measured in situ and for this reason, knowledge of how different soil organisms such as roots, rhizosphere and decomposers contribute to VOC production is limited. The aim of this study was to determine and quantify VOC fluxes and concentrations of different horizons from boreal forest soil. The VOC concentrations and fluxes were measured from Scots pine (Pinus sylvestris) forest soil at the SMEAR II station in southern Finland from 21th of April to 2nd of December in 2016. VOC fluxes were measured using dynamic (flow-through) chambers from five soil collars placed on five different locations. VOC concentrations were also measured in each location from four different soil horizons with the measurement depth 1-107 cm. VOCs were collected from underground gas collectors into the Tenax-Carbopack-B adsorbent tubes using portable pumps ( 100 ml min-1). The VOC concentrations and fluxes of isoprene, 11 monoterpenes, 13 sesquiterpenes and different oxygenated VOCs were measured. Sample tubes were analyzed using thermal desorption-gas chromatograph-mass spectrometry (TD-GC-MS). Soil temperature and soil water content were continuously monitored for each soil horizon. Our preliminary results show that the primary source of VOCs is organic soil layer and the contribution of mineral soil to the VOC formation is minor. VOC fluxes and concentrations were dominated by monoterpenes such as α-pinene, camphene, β-pinene, and Δ3-carene. Monoterpene concentration is almost 10-fold in organic soil compared to the deeper soil layers. However, the highest VOC fluxes on the soil surface were measured in October, whereas the monoterpene concentrations in organic soil were highest in July

  16. Plane and parabolic solar panels

    CERN Document Server

    Sales, J H O

    2009-01-01

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

  17. Parabolic tapers for overmoded waveguides

    Science.gov (United States)

    Doane, J.L.

    1983-11-25

    A waveguide taper with a parabolic profile, in which the distance along the taper axis varies as the square of the tapered dimension, provides less mode conversion than equal length linear tapers and is easier to fabricate than other non-linear tapers.

  18. Carbon dioxide as working fluid for medium and high-temperature concentrated solar thermal systems

    Directory of Open Access Journals (Sweden)

    Van Duong

    2014-03-01

    Full Text Available This paper explores the benefits and drawbacks of using carbon dioxide in solar thermal systems at medium and high operating temperatures. For medium temperatures, application of CO2 in non-imaging-optics based compound parabolic concentrators (CPC combined with evacuated-tube collectors is studied. These collectors have been shown to obtain efficiencies higher than 40% operating at around 200℃ without the need of tracking. Validated numerical models of external compound parabolic concentrators (XCPCs are used to simulate their performance using CO2 as working fluid. For higher temperatures, a mathematical model is implemented to analyze the operating performance of a parabolic trough solar collector (PTC using CO2 at temperatures between 100℃ and 600℃.

  19. Volatile organic compound fluxes and concentrations in London (ClearfLo)

    Science.gov (United States)

    Valach, Amy; Langford, Ben; Nemitz, Eiko; MacKenzie, Rob; Hewitt, Nick

    2014-05-01

    Volatile organic compounds (VOCs) from anthropogenic sources such as fuel combustion or evaporative emissions can directly and indirectly affect human health. Some VOCs, such as benzene and 1,3- butadiene are carcinogens. These and other VOCs contribute to the formation of ozone (O3) and aerosol particles, which have effects on human health and the radiative balance of the atmosphere. Although in the UK VOC emissions are subject to control under European Commission Directive 2008/50/EC and emission reducing technologies have been implemented, urban air pollution remains a concern. Urban air quality is likely to remain a priority since currently >50% of the global population live in urban areas with trends in urbanization and population migration predicted to increase. The ClearfLo project is a large multi-institutional consortium funded by the UK Natural Environment Research Council (NERC) and provides integrated measurements of meteorology, gas phase and particulate composition of the atmosphere over London. Both long term and IOP measurements were made at street and elevated locations at a range of sites across London and its surroundings during 2011 and 2012. Mixing ratios of a selection of nine VOCs were measured using a high sensitivity proton transfer reaction-mass spectrometer (PTR-MS) at a ground level urban background (North Kensington) and kerbside (Marylebone Road) site during the winter IOP. VOC fluxes were measured by virtually disjunct eddy covariance (vDEC) at an elevated urban site (King's College Strand) in Aug-Dec 2012. Our results for the first IOP showed that most of the selected compound concentrations depended on traffic emissions, although there was a marked difference between the urban background and kerbside sites. We identified some temperature effects on VOC concentrations. We also present the first analyses of VOC flux measurements over London. Preliminary analyses indicate most compounds associated with vehicle emissions closely

  20. Multilayer reflective coating for solar energy concentrators

    Energy Technology Data Exchange (ETDEWEB)

    Hernandez, Perla; Almanza, Rafael [Inst. de Ingenieria, Univ. Nacional Autonoma de Mexico, Mexico (Mexico); Cruz-Manjarrez, Hector [Inst. de Fisica, Univ. Nacional Autonoma de Mexico, Mexico (Mexico)

    2008-07-01

    The central objective of this work is determine the optimal parameters for the preparation of compound mirrors of first surface of high reflectance by the magnetron sputtering method that will have a direct application in parabolic trough solar concentrators to use in a hybrid solar-geothermal Geothermal Plant at Cerro Prieto, located to the South-eastern of Mexicali City at the Northwest of Mexico. (orig.)

  1. Position for determining gas-phase volatile organic compound concentrations in transuranic waste containers. Revision 2

    Energy Technology Data Exchange (ETDEWEB)

    Connolly, M.J.; Liekhus, K.J. [Lockheed Martin Idaho Technologies Co., Idaho Falls, ID (United States). Idaho National Engineering and Environmental Lab.; Djordjevic, S.M.; Loehr, C.A.; Spangler, L.R. [Benchmark Environmental Corp. (United States)

    1998-06-01

    In the conditional no-migration determination (NMD) for the test phase of the Waste Isolation Pilot Plant (WIPP), the US Environmental Protection Agency (EPA) imposed certain conditions on the US Department of Energy (DOE) regarding gas phase volatile organic compound (VOC) concentrations in the void space of transuranic (TRU) waste containers. Specifically, the EPA required the DOE to ensure that each waste container has no layer of confinement that contains flammable mixtures of gases or mixtures of gases that could become flammable when mixed with air. The EPA also required that sampling of the headspace of waste containers outside inner layers of confinement be representative of the entire void space of the container. The EPA stated that all layers of confinement in a container would have to be sampled until DOE can demonstrate to the EPA that sampling of all layers is either unnecessary or can be safely reduced. A test program was conducted at the Idaho National Engineering and Environmental Laboratory (INEEL) to demonstrate that the gas phase VOC concentration in the void space of each layer of confinement in vented drums can be estimated from measured drum headspace using a theoretical transport model and that sampling of each layer of confinement is unnecessary. This report summarizes the studies performed in the INEEL test program and extends them for the purpose of developing a methodology for determining gas phase VOC concentrations in both vented and unvented TRU waste containers. The methodology specifies conditions under which waste drum headspace gases can be said to be representative of drum gases as a whole and describes a method for predicting drum concentrations in situations where the headspace concentration is not representative. The methodology addresses the approach for determining the drum VOC gas content for two purposes: operational period drum handling and operational period no-migration calculations.

  2. Volatile organic compound concentrations and emission rates measured over one year in a new manufactured house

    Energy Technology Data Exchange (ETDEWEB)

    Hodgson, Alfred T.; Nabinger, Steven J.; Persily, Andrew K.

    2004-09-01

    A study to measure indoor concentrations and emission rates of volatile organic compounds (VOCs), including formaldehyde, was conducted in a new, unoccupied manufactured house installed at the National Institute of Standards and Technology (NIST) campus. The house was instrumented to continuously monitor indoor temperature and relative humidity, heating and air conditioning system operation, and outdoor weather. It also was equipped with an automated tracer gas injection and detection system to estimate air change rates every 2 h. Another automated system measured indoor concentrations of total VOCs with a flame ionization detector every 30 min. Active samples for the analysis of VOCs and aldehydes were collected indoors and outdoors on 12 occasions from August 2002 through September 2003. Individual VOCs were quantified by thermal desorption to a gas chromatograph with a mass spectrometer detector (GC/MS). Formaldehyde and acetaldehyde were quantified by high performance liquid chromatography (HPLC). Weather conditions changed substantially across the twelve active sampling periods. Outdoor temperatures ranged from 7 C to 36 C. House air change rates ranged from 0.26 h{sup -1} to 0.60 h{sup -1}. Indoor temperature was relatively constant at 20 C to 24 C for all but one sampling event. Indoor relative humidity (RH) ranged from 21% to 70%. The predominant and persistent indoor VOCs included aldehydes (e.g., formaldehyde, acetaldehyde, pentanal, hexanal and nonanal) and terpene hydrocarbons (e.g., a-pinene, 3-carene and d-limonene), which are characteristic of wood product emissions. Other compounds of interest included phenol, naphthalene, and other aromatic hydrocarbons. VOC concentrations were generally typical of results reported for other new houses. Measurements of total VOCs were used to evaluate short-term changes in indoor VOC concentrations. Most of the VOCs probably derived from indoor sources. However, the wall cavity was an apparent source of

  3. Long-term average performance benefits of parabolic trough improvements

    Energy Technology Data Exchange (ETDEWEB)

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

    1980-03-01

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

  4. Long-term stability measurements of low concentration Volatile Organic Compound gas mixtures

    Science.gov (United States)

    Allen, Nick; Amico di Meane, Elena; Brewer, Paul; Ferracci, Valerio; Corbel, Marivon; Worton, David

    2017-04-01

    VOCs (Volatile Organic Compounds) are a class of compounds with significant influence on the atmosphere due to their large anthropogenic and biogenic emission sources. VOC emissions have a significant impact on the atmospheric hydroxyl budget and nitrogen reservoir species, while also contributing indirectly to the production of tropospheric ozone and secondary organic aerosol. However, the global budget of many of these species are poorly constrained. Moreover, the World Meteorological Organization's (WMO) Global Atmosphere Watch (GAW) have set challenging data quality objectives for atmospheric monitoring programmes for these classes of traceable VOCs, despite the lack of available stable gas standards. The Key-VOCs Joint Research Project is an ongoing three-year collaboration with the aim of improving the measurement infrastructure of important atmospheric VOCs by providing traceable and comparable reference gas standards and by validating new measurement systems in support of the air monitoring networks. It focuses on VOC compounds that are regulated by European legislation, that are relevant for indoor air monitoring and for air quality and climate monitoring programmes like the VOC programme established by the WMO GAW and the European Monitoring and Evaluation Programme (EMEP). These VOCs include formaldehyde, oxy[genated]-VOCs (acetone, ethanol and methanol) and terpenes (a-pinene, 1,8-cineole, δ-3-carene and R-limonene). Here we present the results of a novel long term stability study for low concentration formaldehyde, oxy-VOC and terpenes gas mixtures produced by the Key-VOCs consortium with discussion regarding the implementation of improved preparation techniques and the use of novel cylinder passivation chemistries to guarantee mixture stability.

  5. Dibasic Ammonium Phosphate Application Enhances Aromatic Compound Concentration in Bog Bilberry Syrup Wine.

    Science.gov (United States)

    Wang, Shao-Yang; Li, Yi-Qing; Li, Teng; Yang, Hang-Yu; Ren, Jie; Zhang, Bo-Lin; Zhu, Bao-Qing

    2016-12-29

    A nitrogen deficiency always causes bog bilberry syrup wine to have a poor sensory feature. This study investigated the effect of nitrogen source addition on volatile compounds during bog bilberry syrup wine fermentation. The syrup was supplemented with 60, 90, 120 or 150 mg/L dibasic ammonium phosphate (DAP) before fermentation. Results showed that an increase of DAP amounts accelerated fermentation rate, increased alcohol content, and decreased sugar level. Total phenol and total flavonoid content were also enhanced with the increase of DAP amounts. A total of 91 volatile compounds were detected in the wine and their concentrations were significantly enhanced with the increase of DAP. Ethyl acetate, isoamyl acetate, phenethyl acetate, ethyl butanoate, ethyl hexanoate, ethyl octanoate, ethyl decanoate, isobutanol, isoamyl alcohol, levo-2,3-butanediol, 2-phenylethanol, meso-2,3-butanediol, isobutyric acid, hexanoic acid, and octanoic acid exhibited a significant increase of their odor activity value (OAV) with the increase of DAP amounts. Bog bilberry syrup wine possessed fruity, fatty, and caramel flavors as its major aroma, whereas a balsamic note was the least present. The increase of DAP amounts significantly improved the global aroma attributes, thereby indicating that DAP supplementation could promote wine fermentation performance and enhance the sensory quality of bog bilberry syrup wine.

  6. Seasonal cycles of biogenic volatile organic compound fluxes and concentrations in a California citrus orchard

    Directory of Open Access Journals (Sweden)

    S. Fares

    2012-10-01

    Full Text Available Orange trees are widely cultivated in Mediterranean climatic regions where they are an important agricultural crop. Citrus have been characterized as emitters of volatile organic compounds (VOC in chamber studies under controlled environmental conditions, but an extensive characterization at field scale has never been performed using modern measurement methods, and is particularly needed considering the complex interactions between the orchards and the polluted atmosphere in which Citrus is often cultivated. For one year, in a Valencia orange orchard in Exeter, California, we measured fluxes using PTRMS (Proton Transfer Reaction Mass Spectrometer and eddy covariance for the most abundant VOC typically emitted from citrus vegetation: methanol, acetone, and isoprenoids. Concentration gradients of additional oxygenated and aromatic compounds from the ground level to above the canopy were also measured. In order to characterize concentrations of speciated biogenic VOC (BVOC in leaves, we analyzed leaf content by GC-MS (Gas Chromatography – Mass Spectrometery regularly throughout the year. We also characterized in more detail concentrations of speciated BVOC in the air above the orchard by in-situ GC-MS during a few weeks in spring flowering and summer periods. Here we report concentrations and fluxes of the main VOC species emitted by the orchard, discuss how fluxes measured in the field relate to previous studies made with plant enclosures, and describe how VOC content in leaves and emissions change during the year in response to phenological and environmental parameters. The orchard was a source of monoterpenes and oxygenated VOC. The highest emissions were observed during the springtime flowering period, with mid-day fluxes above 2 nmol m−2 s−1 for methanol and up to 1 nmol m−2 s−1 for acetone and monoterpenes. During hot summer days emissions were not as high as we expected considering the

  7. Membrane processes application on the Symphytum officinale and Geranium robertianum extracts concentration to obtain high antioxidative activity compounds

    Directory of Open Access Journals (Sweden)

    Paun Gabriela

    2012-01-01

    Full Text Available The paper reports the successful application of membranes processes to obtain the good quality extracts with compounds of high antioxidative activity and therapeutic value. This study provided investigations on the phenolic compounds from two plant species used in Romanian ethno-medicine and evaluated the antioxidant and cytotoxic activities. Three extracts prepared from Geranium robertianum and Symphytum officinale were concentrated by microfiltration and ultrafiltration. The levels of phenolic compounds and flavonoids were determined by UV-Vis spectroscopy and HPLC. The freeradical scavenging activity of concentrated extracts was determined by DPPH method. The preliminary tests of cytotoxic activity for the concentrated extracts have been carried out on human epidermoid laryngeal carcinoma cell line (Hep-2p and normal monkey kidneys cells (RM. The results showed that all concentrated extracts had a very low cytotoxicity against healthy cells, but a significant cytotoxic effect on Hep-2p tumor cells. The concentrated extracts have a high antioxidant activity (% DPPH inhibition > 80%.

  8. Wind Tunnel Tests of Parabolic Trough Solar Collectors: March 2001--August 2003

    Energy Technology Data Exchange (ETDEWEB)

    Hosoya, N.; Peterka, J. A.; Gee, R. C.; Kearney, D.

    2008-05-01

    Conducted extensive wind-tunnel tests on parabolic trough solar collectors to determine practical wind loads applicable to structural design for stress and deformation, and local component design for concentrator reflectors.

  9. 槽式太阳能腔体式吸热器热力性能分析%Analysis of Thermodynamic Performance of Cavity Absorber in the Parabolic Trough Solar Concentrator

    Institute of Scientific and Technical Information of China (English)

    刘庆君; 刘德有; 朱天宇; 毛宇飞; 王磊

    2015-01-01

    详述了适用于槽式太阳能中低温有机朗肯循环热发电系统的腔体式吸热器的结构形式和聚光原理;并应用TRACEPRO 软件对该吸热器的光学特性进行了分析,证实了该吸热器能够可靠地接收太阳辐射;建立了该吸热器的二维稳态传热计算模型;选用R123作为工质,系统地分析了其在超临界工况下的辐照强度、工作压力、工质流量、环境风速以及保温层厚度等参数对热吸热器热力性能的影响规律。结果表明:吸热器在超临界工况下工作时,适当增加工质流量可以增大其吸热量并保证其安全稳定运行;增加入口压力会增加设备成本,并且不能提高吸热器的性能;合理的保温层厚度可以有效减少热损,使吸热器性能得到改善。研究结果可为设计和搭建腔体式吸热器实验台提供理论参考。%The paper presented the structure and focusing principle of cavity absorber in the parabolic trough solar concentrator that was suitable for low and medium temperature solar thermal electric generation with organic Rankine cycle(ORC). The optical characteristics were studied by TRACEPRO software,and it was approved that the absorber reliably accepted solar radiation. This paper first established a two-dimensional steady-state heat transfer model, and selected R123 as working fluid, then systematically analyzed the major influence factors, including the solar irradiation, working pressure, flow rate, wind speed, and thickness of insulating layer, on the supercritical heat transfer processes. The results show that increasing mass flow rate should be carried out to enhance the heat absorption and keep the absorber tube in the safe state under supercritical condition. Equipment cost rises with increasing the inlet pressure, and can't improve the performance. The suitable insulation thickness can effectively reduce heat loss and improve performance of the absorber. The research results

  10. Separation and concentration of lanthanoids using microcapsules containing acidic organophosphorus compounds as an extractant

    Energy Technology Data Exchange (ETDEWEB)

    Kamio, Eiji; Kondo, Kazuo [Doshisha Univ., Department of Chemical Engineering and Materials Science, Kyoto (Japan)

    2002-06-01

    In this study, we measured the extraction equilibria of lanthanoids with microcapsules containing acidic organophosphorus compound as an extractant and discuss their mutual separation by using a column packed with the microcapsules. The extraction equilibria of lanthanoids into the microcapsules containing 2-ethylhexylphosphonic acid mono-2-ethylhexyl ester (EHPNA) were elucidated and the extraction equilibrium constants were calculated by slope-analysis method. It was suggested that the lanthanoid ions are extracted in the microcapsules in a high loading state. Furthermore, the adsorption behavior of lanthanoids into the column packed with the microcapsules containing EHPNA was observed. It was found that adsorption and elution of lanthanoids are briefly achieved by selecting pH of the feed aqueous solution. However, it was impossible to separate them only in adsorption or elution operation. So, the mutual separation of lanthanoids was investigated using the adsorption column connected to the development column containing microcapsules. By selecting pH of the eluent, each metal was separated mutually in more than 95% of purity. The metal ions in the eluent from the development column could be concentrated by treating it with a column packed with the microcapsules containing di(2-ethylhexyl) phosphoric acid (D2EHPA). Considering these information, it will be possible to design a continuous extracting, separating and concentrating reactor of lanthanoids using a column packed with the microcapsules. (author)

  11. Design of Novel Compound Fresnel Lens for High-Performance Photovoltaic Concentrator

    Directory of Open Access Journals (Sweden)

    Lei Jing

    2012-01-01

    Full Text Available We present a new design of compound Fresnel-R concentrator which is composed of two lenses: a primary lens (Fresnel lens that works by total internal reflection at outer sawteeth but refraction at inner sawteeth, and a ringed secondary lens that works by refraction. In contrast to previous Fresnel lens concentrators, this design increases the acceptance angle, improves the irradiance uniformity on the solar cell, and reduces the aspect ratio significantly. Meanwhile several sawteeth of the primary Fresnel lens can correspond to a same ring of secondary lens, which will efficiently lower the complexity of designing and manufacturing. Moreover, in order to reduce the influence of manufacturing tolerances and to increase the optical efficiency further, the central part of the bottom of the secondary lens which directly adhered to the solar cell is designed as a cone-shaped prism to collect the sunlight that does not reach the solar cell. Finally, we provide simulations and analyses of the design method an optical efficiency more than 80% and an aspect ratio smaller than 0.5 can be achieved.

  12. Characterizing non-methane volatile organic compounds emissions from a swine concentrated animal feeding operation

    Science.gov (United States)

    Rumsey, Ian C.; Aneja, Viney P.; Lonneman, William A.

    2012-02-01

    Emissions of non-methane volatile organic compounds (NMVOCs) were determined from a swine concentrated animal feeding operation (CAFO) in North Carolina. NMVOCs were measured in air samples collected in SUMMA and fused-silica lined (FSL) canisters and were analyzed using a gas chromatography flame ionization detection (GC-FID) system. Measurements were made from both an anaerobic lagoon and barn in each of the four seasonal sampling periods during the period June 2007 through April 2008. In each sampling period, nine to eleven canister samples were taken from both the anaerobic lagoon and barn over a minimum of four different days during a period of ˜1 week. Measurements of meteorological and physiochemical parameters were also made during the sampling period. In lagoon samples, six NMVOCs were identified that had significantly larger emissions in comparison to other NMVOCs. This included three alcohols (ethanol, 2-ethyl-1-hexanol, and methanol), two ketones (acetone and methyl ethyl ketone (MEK)) and an aldehyde (acetaldehyde). The overall average fluxes for these NMVOCs, ranged from 0.18 μg m -2 min -1 for 2-ethyl-1-hexanol to 2.11 μg m -2 min -1 for acetone, with seasonal fluxes highest in the summer for four (acetone, acetaldehyde, 2-ethyl-1-hexanol and MEK) of the six compounds In barn samples, there were six NMVOCs that had significantly larger concentrations and emissions in comparison to other NMVOCs. These consisted of two alcohols (methanol and ethanol), an aldehyde (acetaldehyde), two ketones (acetone and 2,3-butanedione), and a phenol (4-methylphenol). Overall average barn concentration ranged from 2.87 ppb for 4-methylphenol to 16.12 ppb for ethanol. Overall average normalized barn emission rates ranged from 0.10 g day -1 AU -1 (1 AU (animal unit) = 500 kg of live animal weight) for acetaldehyde to 0.45 g day -1 AU -1 for ethanol. The NMVOCs, 4-methylphenol and 2,3-butanedione, which have low odor thresholds (odor thresholds = 1.86 ppb and 0

  13. Estradiol and endocrine disrupting compounds adversely affect development of sea urchin embryos at environmentally relevant concentrations

    Energy Technology Data Exchange (ETDEWEB)

    Roepke, Troy A. [Bodega Marine Laboratory, University of California, Davis, POB 247, Bodega Bay, CA 94923 (United States); Snyder, Mark J. [Bodega Marine Laboratory, University of California, Davis, POB 247, Bodega Bay, CA 94923 (United States); Cherr, Gary N. [Bodega Marine Laboratory, University of California, Davis, POB 247, Bodega Bay, CA 94923 (United States) and Departments of Environmental Toxicology and Nutrition, One Shields Avenue, University of California, Davis, CA 95616 (United States)]. E-mail: gncherr@ucdavis.edu

    2005-01-26

    Environmental endocrine disrupting compounds (EDCs) are a wide variety of chemicals that typically exert effects, either directly or indirectly, through receptor-mediated processes, thus mimicking endogenous hormones and/or inhibiting normal hormone activities and metabolism. Little is known about the effects of EDCs on echinoderm physiology, reproduction and development. We exposed developing sea urchin embryos (Strongylocentrotus purpuratus and Lytechinus anamesus) to two known EDCs (4-octylphenol (OCT), bisphenol A (BisA)) and to natural and synthetic reproductive hormones (17{beta}-estradiol (E{sub 2}), estrone (E{sub 1}), estriol (E{sub 3}), progesterone (P{sub 4}) and 17{alpha}-ethynylestradiol (EE{sub 2})). In addition, we studied two non-estrogenic EDCs, tributyltin (TBT) and o,p-DDD. Successful development to the pluteus larval stage (96 h post-fertilization) was used to define EDC concentration-response relationships. The order of compound potency based on EC{sub 50} values for a reduction in normal development was as follows: TBT {sub L.anamesus} > OCT > TBT {sub S.{sub p}}{sub urpuratus} >> E{sub 2} > EE{sub 2} > DDD >> BisA > P{sub 4} > E{sub 1} >> E{sub 3}. The effect of TBT was pronounced even at concentrations substantially lower than those commonly reported in heavily contaminated areas, but the response was significantly different in the two model species. Sea urchin embryos were generally more sensitive to estrogenic EDCs and TBT than most other invertebrate larvae. Stage-specific exposure experiments were conducted to determine the most sensitive developmental periods using blastula, gastrula and post-gastrula (pluteus) stages. The stage most sensitive to E{sub 2}, OCT and TBT was the blastula stage with less overall sensitivity in the gastrula stage, regardless of concentration. Selective estrogen receptor modulators (SERMs) were added to the experiments individually and in combination with estrogenic EDCs to interfere with potential receptor

  14. Concentrations and fluxes of biogenic volatile organic compounds above a Mediterranean macchia ecosystem in Western Italy

    Directory of Open Access Journals (Sweden)

    B. Davison

    2009-02-01

    Full Text Available Emission rates and concentrations of biogenic volatile organic compounds (BVOCs were measured at a Mediterranean coastal site at Castelporziano, approximately 25 km south-west of Rome, between 7 May and 3 June 2007, as part of the ACCENT-VOCBAS field campaign on biosphere-atmosphere interactions. Concentrations and emission rates were measured using the disjunct eddy covariance method utilizing three different proton transfer reaction mass spectrometers (PTR-MS for BVOC mixing ratio measurements and sonic anemometers for three-dimensional high-frequency wind measurements. Depending on the measurement period and the instrument, the median volume mixing ratios were 1.6–3.5 ppbv for methanol, 0.4–1.5 ppbv for acetaldehyde, 1.0–2.5 ppbv for acetone, 0.10–0.17 ppbv for isoprene, and 0.18–0.30 ppbv for monoterpenes. A diurnal cycle in mixing ratios was apparent with daytime maxima for methanol, acetaldehyde, acetone, and isoprene. The median fluxes were 370–440 μg m−2 h−1 for methanol, 180–360 μg m−2 h−1 for acetaldehyde, 180–450 μg m−2 h−1 for acetone, 71–290 μg m−2 h−1 for isoprene, and 240–860 μg m−2 h−1 for monoterpenes.

  15. 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.

  16. A critical review of reported air concentrations of organic compounds in aircraft cabins.

    Science.gov (United States)

    Nagda, N L; Rector, H E

    2003-09-01

    This paper presents a review and assessment of aircraft cabin air quality studies with measured levels of volatile and semivolatile organic compounds (VOCs and SVOCs). VOC and SVOC concentrations reported for aircraft cabins are compared with those reported for residential and office buildings and for passenger compartments of other types of transportation. An assessment of measurement technologies and quality assurance procedures is included. The six studies reviewed in the paper range in coverage from two to about 30 flights per study. None of the monitored flights included any unusual or episodic events that could affect cabin air quality. Most studies have used scientifically sound methods for measurements. Study results indicate that under routine aircraft operations, contaminant levels in aircraft cabins are similar to those in residential and office buildings, with two exceptions: (1). levels of ethanol and acetone, indicators of bioeffluents and chemicals from consumer products are higher in aircraft than in home or office environments, and (2). levels of certain chlorinated hydrocarbons and fuel-related contaminants are higher in residential/office buildings than in aircraft. Similarly, ethanol and acetone levels are higher in aircraft than in other transportation modes but the levels of some pollutants, such as m-/p-xylenes, tend to be lower in aircraft.

  17. Occurrence and concentrations of pharmaceutical compounds in deep groundwater used for public drinking-water supply in California

    Science.gov (United States)

    Fram, Miranda S.; Belitz, Kenneth

    2011-01-01

    Pharmaceutical compounds were detected at low concentrations in 2.3% of 1231 samples of groundwater (median depth to top of screened interval in wells = 61 m) used for public drinking-water supply in California. Samples were collected statewide for the California State Water Resources Control Board's Groundwater Ambient Monitoring and Assessment (GAMA) Program. Of 14 pharmaceutical compounds analyzed, 7 were detected at concentrations greater than or equal to method detection limits: acetaminophen (used as an analgesic, detection frequency 0.32%, maximum concentration 1.89 μg/L), caffeine (stimulant, 0.24%, 0.29 μg/L), carbamazepine (mood stabilizer, 1.5%, 0.42 μg/L), codeine (opioid analgesic, 0.16%, 0.214 μg/L), p-xanthine (caffeine metabolite, 0.08%, 0.12 μg/L), sulfamethoxazole (antibiotic, 0.41%, 0.17 μg/L), and trimethoprim (antibiotic, 0.08%, 0.018 μg/L). Detection frequencies of pesticides (33%), volatile organic compounds not including trihalomethanes (23%), and trihalomethanes (28%) in the same 1231 samples were significantly higher. Median detected concentration of pharmaceutical compounds was similar to those of volatile organic compounds, and higher than that of pesticides. Pharmaceutical compounds were detected in 3.3% of the 855 samples containing modern groundwater (tritium activity > 0.2 TU). Pharmaceutical detections were significantly positively correlated with detections of urban-use herbicides and insecticides, detections of volatile organic compounds, and percentage of urban land use around wells. Groundwater from the Los Angeles metropolitan area had higher detection frequencies of pharmaceuticals and other anthropogenic compounds than groundwater from other areas of the state with similar proportions of urban land use. The higher detection frequencies may reflect that groundwater flow systems in Los Angeles area basins are dominated by engineered recharge and intensive groundwater pumping.

  18. Parabolic troughs to increase the geothermal wells flow enthalpy

    Energy Technology Data Exchange (ETDEWEB)

    Lentz, Alvaro; Almanza, Rafael [Engineering Institute, National Autonomous University of Mexico, Building 12, Cuidad Universitaria, Mexico D.F., A.P. 70-472, C.P. 04510 (Mexico)

    2006-10-15

    This work investigates the feasibility of using parabolic trough solar field to increase the enthalpy from geothermal wells' flow in order to increase the steam tons; in addition, it is possible to prevent silica deposition in the geothermal process. The high levels of irradiance in Northwestern Mexico make it possible to integrate a solar-geothermal hybrid system that uses two energy resources to provide steam for the geothermal cycle, like the Cerro Prieto geothermal field. The plant consists of a geothermal well, a parabolic trough solar field in series, flash separator, steam turbine and condenser. Well '408' of Cerro Prieto IV has enthalpy of 1566kJ/kg and its quality must be increased by 10 points, which requires a {delta}h of 194.4kJ/kg. Under these considerations the parabolic troughs area required will be 9250m{sup 2}, with a flow of 92.4tons per hour (25.67kg/s). The solar field orientation is a N-S parabolic trough concentrator. The silica content in the Cerro Prieto geothermal brine causes problems for scaling at the power facility, so scale controls must be considered. (author)

  19. Characterizing reduced sulfur compounds emissions from a swine concentrated animal feeding operation

    Science.gov (United States)

    Rumsey, Ian C.; Aneja, Viney P.; Lonneman, William A.

    2014-09-01

    Reduced sulfur compounds (RSCs) emissions from concentrated animal feeding operations (CAFOs) have become a potential environmental and human health concern, as a result of changes in livestock production methods. RSC emissions were determined from a swine CAFO in North Carolina. RSC measurements were made over a period of ≈1 week from both the barn and lagoon during each of the four seasonal periods from June 2007 to April 2008. During sampling, meteorological and other environmental parameters were measured continuously. Seasonal hydrogen sulfide (H2S) barn concentrations ranged from 72 to 631 ppb. Seasonal dimethyl sulfide (DMS; CH3SCH3) and dimethyl disulfide (DMDS; CH3S2CH3) concentrations were 2-3 orders of magnitude lower, ranging from 0.18 to 0.89 ppb and 0.47 to 1.02 ppb, respectively. The overall average barn emission rate was 3.3 g day-1 AU-1 (AU (animal unit) = 500 kg of live animal weight) for H2S, which was approximately two orders of magnitude higher than the DMS and DMDS overall average emissions rates, determined as 0.017 g day-1 AU-1 and 0.036 g day-1 AU-1, respectively. The overall average lagoon flux was 1.33 μg m-2 min-1 for H2S, which was approximately an order of magnitude higher than the overall average DMS (0.12 μg m-2 min-1) and DMDS (0.09 μg m-2 min-1) lagoon fluxes. The overall average lagoon emission for H2S (0.038 g day-1 AU-1) was also approximately an order of magnitude higher than the overall average DMS (0.0034 g day-1 AU-1) and DMDS (0.0028 g day-1 AU-1) emissions. H2S, DMS and DMDS have offensive odors and low odor thresholds. Over all four sampling seasons, 77% of 15 min averaged H2S barn concentrations were an order of magnitude above the average odor threshold. During these sampling periods, however, DMS and DMDS concentrations did not exceed their odor thresholds. The overall average barn and lagoon emissions from this study were used to help estimate barn, lagoon and total (barn + lagoon) RSC emissions from swine CAFOs

  20. Nondestructive pollution exposure assessment in the European hedgehog (Erinaceus europaeus): III. Hair as an indicator of endogenous organochlorine compound concentrations.

    Science.gov (United States)

    D'Havé, Helga; Scheirs, Jan; Covaci, Adrian; Schepens, Paul; Verhagen, Ron; De Coen, Wim

    2006-01-01

    Concentrations of organochlorine persistent pollutants were investigated in tissues of the European hedgehog (Erinaceus europaeus). Road kills and carcasses from wildlife rescue centers were used to characterize organochlorine compound tissue distribution and tissue profile dissimilarities (hair, liver, kidney, muscle, and adipose tissue). The most important contaminants were polychlorinated biphenyls (PCBs), chlordanes (CHLs), and DDTs, with median concentrations of 75, 5.1, and 1.4 ng/g liver wet weight, respectively. Median levels for the remaining compounds-hexachlorobenzene (HCB), hexachlorocyclohexanes (HCHs), and octachlorostyrene-were less than 0.5 ng/g liver wet weight. Compared to results with other mammalian wildlife, the present results indicate that hedgehogs may accumulate considerable concentrations of organochlorine compounds. Polychlorinated biphenyls and HCB preferably accumulated in liver and muscle tissue. Concentrations of DDTs and HCHs were highest in muscle tissue and hair, respectively. Octachlorostyrene and CHL levels were predominant in liver. The observed positive relationships between concentrations in hair and internal tissues for PCBs, DDTs, HCB, HCHs, and CHLs (0.49 hedgehog hair as a nondestructive biomonitoring tool regarding pollution with organochlorine compounds and the promising role of the hedgehog as a mammalian indicator species of pollution in terrestrial environments.

  1. Nonlinear elliptic-parabolic problems

    CERN Document Server

    Kim, Inwon C

    2012-01-01

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

  2. PERFORMANCE SIMULATION OF PARABOLIC TROUGH SOLAR COLLECTOR USING TWO FLUIDS (THERMIC OIL AND MOLTEN SALT)

    OpenAIRE

    T. E. Boukelia; M. S. Mecibah; A. Laouafi

    2016-01-01

    The Parabolic trough solar collector is considered as one of the most proven, mature and commercial concentrating solar systems implemented in arid and semi-arid regions for energy production. It focuses sunlight onto a solar receiver by using mirrors and is finally converted to a useful thermal energy by means of a heat transfer fluid. The aims of this study are (i) to develop a new methodology for simulation and performance evaluation of parabolic trough solar collector, in addition (i) to ...

  3. Proceedings: Fourth Parabolic Dish Solar Thermal Power Program Review

    Science.gov (United States)

    1983-01-01

    The results of activities within the parabolic dish technology and applications development program are presented. Stirling, organic Rankine and Brayton module technologies, associated hardware and test results to date; concentrator development and progress; economic analyses; and international dish development activities are covered. Two panel discussions, concerning industry issues affecting solar thermal dish development and dish technology from a utility/user perspective, are also included.

  4. Parabolic-trough solar collectors and their applications

    Energy Technology Data Exchange (ETDEWEB)

    Fernandez-Garcia, A.; Zarza, E.; Valenzuela, L. [CIEMAT-Plataforma Solar de Almeria, Ctra. Senes, km. 4, Tabernas (Almeria) 04200 (Spain); Perez, M. [Departamento de Fisica Aplicada, Universidad de Almeria, Almeria 04120 (Spain)

    2010-09-15

    This paper presents an overview of the parabolic-trough collectors that have been built and marketed during the past century, as well as the prototypes currently under development. It also presents a survey of systems which could incorporate this type of concentrating solar system to supply thermal energy up to 400 C, especially steam power cycles for electricity generation, including examples of each application. (author)

  5. Parabolic dish reflectors for solar applications approximated by simple surfaces

    OpenAIRE

    Broman, Lars; Broman, Arne

    1996-01-01

    Two different concentrating mirrors have been constructed that resemble parabolic dish reflectors. Both mirrors are made of slightly curved strips of flat, bendable material. The strips of the most simplified mirror have only large-radius circles and straight lines as boundaries. The necessary equations for making the mirrors have been derived. Also a simple way to make a stiff, lightweight frame and support for the mirror strips has been developed. Models of the mirrors have been built and s...

  6. Blood serum concentrations of perfluorinated compounds in men from Greenlandic Inuit and European populations

    NARCIS (Netherlands)

    Lindh, C.H.; Rylander, L.; Toft, G.; Axmon, A.; Rignell-Hydbom, A.; Giwercman, A.; Pedersen, H.S.; Góalczyk, K.; Ludwicki, J.K.; Zvyezday, V.; Vermeulen, R.; Lenters, V.C.; Heederik, D.; Bonde, J.P.; Jönsson, B.A.G.

    2012-01-01

    Perfluorinated compounds (PFCs), such as perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA), are used in large quantities. They are persistent and found in measurable levels in human serum around the world. They have been associated with developmental, hepatic, and carcinogenic

  7. Occurrence and concentrations of pharmaceutical compounds in groundwater used for public drinking-water supply in California

    Energy Technology Data Exchange (ETDEWEB)

    Fram, Miranda S., E-mail: mfram@usgs.gov [U.S. Geological Survey California Water Science Center, 6000 J Street, Placer Hall, Sacramento, CA 95819-6129 (United States); Belitz, Kenneth, E-mail: kbelitz@usgs.gov [U.S. Geological Survey California Water Science Center, 4165 Spruance Road, Suite 200, San Diego, CA 95101-0812 (United States)

    2011-08-15

    Pharmaceutical compounds were detected at low concentrations in 2.3% of 1231 samples of groundwater (median depth to top of screened interval in wells = 61 m) used for public drinking-water supply in California. Samples were collected statewide for the California State Water Resources Control Board's Groundwater Ambient Monitoring and Assessment (GAMA) Program. Of 14 pharmaceutical compounds analyzed, 7 were detected at concentrations greater than or equal to method detection limits: acetaminophen (used as an analgesic, detection frequency 0.32%, maximum concentration 1.89 {mu}g/L), caffeine (stimulant, 0.24%, 0.29 {mu}g/L), carbamazepine (mood stabilizer, 1.5%, 0.42 {mu}g/L), codeine (opioid analgesic, 0.16%, 0.214 {mu}g/L), p-xanthine (caffeine metabolite, 0.08%, 0.12 {mu}g/L), sulfamethoxazole (antibiotic, 0.41%, 0.17 {mu}g/L), and trimethoprim (antibiotic, 0.08%, 0.018 {mu}g/L). Detection frequencies of pesticides (33%), volatile organic compounds not including trihalomethanes (23%), and trihalomethanes (28%) in the same 1231 samples were significantly higher. Median detected concentration of pharmaceutical compounds was similar to those of volatile organic compounds, and higher than that of pesticides. Pharmaceutical compounds were detected in 3.3% of the 855 samples containing modern groundwater (tritium activity > 0.2 TU). Pharmaceutical detections were significantly positively correlated with detections of urban-use herbicides and insecticides, detections of volatile organic compounds, and percentage of urban land use around wells. Groundwater from the Los Angeles metropolitan area had higher detection frequencies of pharmaceuticals and other anthropogenic compounds than groundwater from other areas of State with similar proportions of urban land use. The higher detection frequencies may reflect that groundwater flow systems in Los Angeles area basins are dominated by engineered recharge and intensive groundwater pumping. - Highlights: {yields

  8. Evaluation of the bimetallic receiver Cu-Fe under the flexion phenomenon in parabolic concentrators in the direct steam generation; Evaluacion del receptor bimetalico Cu-Fe bajo el fenomeno de flexion, en concentradores parabolicos en la generacion directa de vapor

    Energy Technology Data Exchange (ETDEWEB)

    Flores, Vicente; Lentz, Alvaro; Almanza, Rafael [Universidad Nacional Autonoma de Mexico, Mexico, D.F. (Mexico)

    2000-07-01

    In this paper the results of experimental tests as a part of the study of the flexion phenomenon of the absorbent tube in concentrators of parabolic channel during the process of direct steam generation (GDV), are presented. The flexion phenomenon of the tube has already been studied, in which it has been established that occurs under conditions of change of temperature gradients in the tube surface, when a stratified flow pattern of appears, which leads to a local overheating of the internal wall of the receiver, when the two phase flow begins, with relatively low massic flows. In the normal configuration of the absorbent iron tube, this one is surrounded with a glass tube to avoid thermal losses to the environment: when the metallic tube bends due to thermal stresses, displacements of 6 cm are reached for wrought iron with a wall thickness of 1.9 mm with selective film: for wrought iron with a wall thickness of 3.8 mm without selective film nor transparent cover bendings of 3 cm have been attained. This way the glass tube is subjected to a cross sectional shearing stress when the absorber touches it during its bending, giving rise also to the rupture of the same. In order to give a solution to this problem, at the Instituto de Engineering, a bi-metallic copper- steel tube 3 m long and 32 mm of diameter was built and installed in the parabolic concentrator and the flexion phenomenon was experienced. Results of experimental tests for the steel and the bimetallic steel receiver, without the glass cover nor the selective film and for the bimetallic receiver with the glass cover, are presented. They are compared among them departing from the temperatures in the lower and the upper part of the cross-sectional section of the tube and of the flexion of each one, concluding that the compound receiver copper-steel, up to now, fulfills better the expectations of eliminating the flexion phenomenon under the operating conditions of the solar plant during the GDV. [Spanish] Se

  9. Planar solar concentrator featuring alignment-free total-internal-reflection collectors and an innovative compound tracker.

    Science.gov (United States)

    Teng, Tun-Chien; Lai, Wei-Che

    2014-12-15

    This study proposed a planar solar concentrator featuring alignment-free total-internal-reflection (TIR) collectors and an innovative compound tracker. The compound tracker, combining a mechanical single-axis tracker and scrollable prism sheets, can achieve a performance on a par with dual-axis tracking while reducing the cost of the tracking system and increasing its robustness. The alignment-free TIR collectors are assembled on the waveguide without requiring alignment, so the planar concentrator is relatively easily manufactured and markedly increases the feasibility for use in large concentrators. Further, the identical TIR collector is applicable to various-sized waveguide slab without requiring modification, which facilitates flexibility regarding the size of the waveguide slab. In the simulation model, the thickness of the slab was 2 mm, and its maximal length reached 6 m. With an average angular tolerance of ±0.6°, and after considering both the Fresnel loss and the angular spread of the sun, the simulation indicates that the waveguide concentrator of a 1000-mm length provides the optical efficiencies of 62-77% at the irradiance concentrations of 387-688, and the one of a 2000-mm length provides the optical efficiencies of 52-64.5% at the irradiance concentrations of 645-1148. Alternatively, if a 100-mm horizontally staggered waveguide slab is collocated with the alignment-free TIR collectors, the optical efficiency would be greatly improved up to 91.5% at an irradiance concentration of 1098 (C(geo) = 1200X).

  10. Effect of Aerogel Particle Concentration on Mechanical Behavior of Impregnated RTV 655 Compound Material for Aerospace Applications

    Directory of Open Access Journals (Sweden)

    Firouzeh Sabri

    2014-01-01

    Full Text Available Aerogels are a unique class of materials with superior thermal and mechanical properties particularly suitable for insulating and cryogenic storage applications. It is possible to overcome geometrical restrictions imposed by the rigidity of monolithic polyurea cross-linked silica aerogels by encapsulating micrometer-sized particles in a chemically resistant thermally insulating elastomeric “sleeve.” The ultimate limiting factor for the compound material’s performance is the effect of aerogel particles on the mechanical behavior of the compound material which needs to be fully characterized. The effect of size and concentration of aerogel microparticles on the tensile behavior of aerogel impregnated RTV655 samples was explored both at room temperature and at 77 K. Aerogel microparticles were created using a step-pulse pulverizing technique resulting in particle diameters between 425 μm and 90 μm and subsequently embedded in an RTV 655 elastomeric matrix. Aerogel particle concentrations of 25, 50, and 75 wt% were subjected to tensile tests and behavior of the compound material was investigated. Room temperature and cryogenic temperature studies revealed a compound material with rupture load values dependent on (1 microparticle size and (2 microparticle concentration. Results presented show how the stress elongation behavior depends on each parameter.

  11. Focusing characteristics of a 4$\\pi$ parabolic mirror light-matter interface

    CERN Document Server

    Alber, Lucas; Bader, Marianne; Mantel, Klaus; Sondermann, Markus; Leuchs, Gerd

    2016-01-01

    Focusing with a 4$\\pi$ parabolic mirror allows for concentrating light from nearly the complete solid angle. So far, this idea could not be exploited to enable diffraction limited focusing from more than half solid angle. We present the focusing properties of a 4$\\pi$ parabolic mirror experimentally characterized with a single $^{174}$Yb$^{+}$ ion as a mobile point scatterer. The ion is trapped in a vacuum environment with a movable high optical access Paul trap. We demonstrate an effective focal spot size of 209 nm in lateral and 551 nm in axial direction. Such tight focusing allows us to build an efficient light-matter interface. Our findings agree with numerical simulations incorporating a finite ion temperature and interferometrically measured wavefront aberrations induced by the parabolic mirror. We point at further technological improvements and discuss the general scope of applications of a 4$\\pi$ parabolic mirror.

  12. Numerical Solution of Parabolic Equations

    DEFF Research Database (Denmark)

    Østerby, Ole

    These lecture notes are designed for a one-semester course on finite-difference methods for parabolic equations. These equations which traditionally are used for describing diffusion and heat-conduction problems in Geology, Physics, and Chemistry have recently found applications in Finance Theory....... Among the special features of this book can be mentioned the presentation of a practical approach to reliable estimates of the global error, including warning signals if the reliability is questionable. The technique is generally applicable for estimating the discretization error in numerical...... approximations which depend on a step size, such as numerical integration and solution of ordinary and partial differential equations. An integral part of the error estimation is the estimation of the order of the method and can thus satisfy the inquisitive mind: Is the order what we expect it to be from theopry...

  13. 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. 

  14. Determination of free and bound phenolic compounds in soy isoflavone concentrate using a PFP fused core column.

    Science.gov (United States)

    Verardo, Vito; Riciputi, Ylenia; Garrido-Frenich, Antonia; Caboni, Maria Fiorenza

    2015-10-15

    In the last years, the consumption of soy-based foods has increased due to the health benefits related to soy bioactives like phenolic compounds. Thus, in the present study, a new chromatographic method using reverse-phase high performance liquid chromatography coupled to diode array detection (RP-HPLC/DAD) was developed using a fused core pentafluorophenyl (PFP) column. The established method allowed the determination of twenty-one free phenolic compounds and eleven bound phenolics in a soy isoflavone concentrate. The method was validated in terms of precision and recovery. Intra and inter-day precision were less than 5% (% RSD) and the recovery was between 97.4% and 103.6%. Limits of quantification (LOQs) ranged between 0.093 and 0.443 μg/mL. Because of that, PFP stationary phase can be easily applied for routine determination of phenolic compounds in soy based foods.

  15. Blood serum concentrations of perfluorinated compounds in men from Greenlandic Inuit and European populations

    DEFF Research Database (Denmark)

    Lindh, Christian H; Rylander, Lars; Toft, Gunnar

    2012-01-01

    Perfluorinated compounds (PFCs), such as perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA), are used in large quantities. They are persistent and found in measurable levels in human serum around the world. They have been associated with developmental, hepatic, and carcinogenic ef...

  16. [Commentary on] Serum vaccine antibody concentrations in children exposed to perfluorinated compounds

    DEFF Research Database (Denmark)

    Grandjean, P.; Andersen, Elisabeth Wreford; Budtz-Jorgenser

    2012-01-01

    The article presents insights into a study which examined the role of perfluorinated compounds (PFC) in antibody response to childhood vaccinations. The prevalence of perfluorooctane sulfonic acid (PFOS) and perfluorooctanoic acid (PFOA) which were mentioned in the study was reported by the U...

  17. 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.

  18. Analysis of the Quality of Parabolic Flight

    Science.gov (United States)

    Lambot, Thomas; Ord, Stephan F.

    2016-01-01

    Parabolic flights allow researchers to conduct several 20 second micro-gravity experiments in the course of a single day. However, the measurement can have large variations over the course of a single parabola, requiring the knowledge of the actual flight environment as a function of time. The NASA Flight Opportunities program (FO) reviewed the acceleration data of over 400 parabolic flights and investigated the quality of micro-gravity for scientific purposes. It was discovered that a parabolic flight can be segmented into multiple parts of different quality and duration, a fact to be aware of when planning an experiment.

  19. Sensing of the concentration and enantiomeric excess of chiral compounds with tropos ligand derived metal complexes.

    Science.gov (United States)

    Zhang, Peng; Wolf, Christian

    2013-08-11

    Palladium(II) complexes carrying chromophoric tropos ligands show a characteristic UV change and strong Cotton effects upon coordination of amino alcohols or diamines. The distinct (chir)optical responses can be used for instantaneous in situ determination of the concentration and ee of diamines and amino alcohols at low concentrations.

  20. Variability of suspended particulate matter concentrations and organic compounds in frontal zones of the Atlantic and Southern oceans

    Science.gov (United States)

    Nemirovskaya, I. A.; Kravchishina, M. D.

    2016-01-01

    The concentrations of suspended particulate matter (SPM) and particulate forms of the organic compounds (hydrocarbons, lipids, and chlorophyll a) were determined in the surface water layers of the Atlantic and Southern oceans during February to May of 2012 and 2014. It was found that the distribution of concentrations of the studied components is mainly affected by the location of frontal zones. When ice cover forms in the Southern Ocean, the changes in water temperature and phytoplankton development at the ice-water interface result in an increase of the concentrations of SPM, chlorophyll a, and, to a lesser extent, of lipids and hydrocarbons in the surface water layer. The occasional sharp increase of hydrocarbon concentrations caused by anthropogenic pollution was registered at local parts of water areas in the east of the Atlantic Ocean, as well as in the North and Baltic seas.

  1. Seasonal variations in the concentrations of lipophilic compounds and phenolic acids in the roots of Echinacea purpurea and Echinacea pallida.

    Science.gov (United States)

    Thomsen, Maria O; Fretté, Xavier C; Christensen, Kathrine B; Christensen, Lars P; Grevsen, Kai

    2012-12-12

    Roots of Echinacea purpurea and Echinacea pallida cultivated for 4 years in a North European climate were analyzed for seasonal variations in the concentrations of lipophilic constituents (alkamides, ketoalkenes, and ketoalkynes) and phenolic acids by harvesting five times during 1 year to establish the optimal time for harvest. A total of 16 alkamides, three ketoalkenes, two ketoalkynes, and four phenolic acids (echinacoside, cichoric acid, caftaric acid, and chlorogenic acid) were identified in aqueous ethanolic (70%) extracts by liquid chromatography-mass spectrometry and quantified by reverse-phase high-performance liquid chromatography. The major alkamides in the roots of E. purpurea were at their lowest concentration in the middle of autumn and early winter, and the total concentration of lipophilic compounds in E. pallida showed the same pattern. Moreover, all of the major phenolic acids in E. purpurea were at their highest concentrations in spring. The optimal harvest time in spring is in contrast to normal growing guidelines; hence, this specific information of seasonal variations in the concentrations of lipophilic and phenolic compounds in E. purpurea and E. pallida is valuable for research, farmers, and producers of medicinal preparations.

  2. Correlation between Odor Concentration and Volatile Organic Compounds (VOC) Composition of Environmental Tobacco Smoke (ETS).

    Science.gov (United States)

    Noguchi, Miyuki; Tanaka, Saya; Watanabe, Kaede; Yamasaki, Akihiro

    2016-10-09

    We examined the correlation between the odor concentration and the chemical composition of environmental tobacco smoke (ETS). Three types of ETS samples were prepared: secondhand smoke (SHS), thirdhand smoke (THS), and field ETS samples from an outside smoking area. The odor concentrations of the ETS, SHS, and THS samples were determined by the triangle-odor-bag method, and the chemical compositions were determined by proton transfer mass spectrometry. The odor concentration of the SHS samples was three or four orders of magnitude higher than that of the field ETS samples, and three orders of magnitude higher than that of the THS samples. The concentration ratios of the constituent chemicals in THS to those in SHS were about 10(-4), corresponding to the ratio of the odor concentration. The concentration ratios of the constituent chemicals in the field ETS samples were much lower than the ratios of the odor concentrations. This suggests that the main contributing components to the odor of the field ETS samples are different from those in SHS and THS. The main contributors of the odor in the field ETS samples could be acetaldehyde, acetonitrile, acetic acid, and other unknown components with a mass-to-charge ratio (m/z) of 39 and 43.

  3. Trends in air concentration and deposition at background monitoring sites in Sweden - major inorganic compounds, heavy metals and ozone

    Energy Technology Data Exchange (ETDEWEB)

    Kindbom, K.; Svensson, Annika; Sjoeberg, K.; Pihl Karlsson, G.

    2001-09-01

    This report describes concentrations in air of sulphur compounds, soot, nitrogen compounds and ozone in Sweden between 1985-1998. Time trends of concentration in precipitation and deposition of sulphate, nitrate, ammonium, acidity, base cations and chloride in six different regions covering Sweden are evaluated during the period 1983-1998. Trends of heavy metals in precipitation have been analysed for the period 1983-1998 and the change in heavy metal concentration, 1975-1995, in mosses is described. Data used in the trend analyses originates from measurements performed at six Swedish EMEP stations and from approximately 25 stations within the national Precipitation Chemistry Network. Two different statistical methods, linear regression and the non-parametric Mann Kendall test, have been used to evaluate changes in annual mean values. Time trends of concentration of sulphur dioxide, particulate sulphate, soot, nitrogen dioxide, total nitrate and total ammonium in air show highly significant decreasing trends, except for soot at one station in northern Sweden. Concentrations of ozone have a strong seasonal variation with a peak occurring in spring every year. However, annual ozone concentrations show no obvious trends in spite of decreasing emissions of the precursors NOx and VOC. A slight indication of a decreasing trend in the number of ozone episodes might be seen from 1990 to 1998. Sulphate concentrations in precipitation and deposition show strongly significant decreasing trends in the whole country. Concentrations and deposition of nitrate and ammonium have been decreasing in all areas except for nitrate at stations in south-west and north-west Sweden and ammonium in south-west Sweden. Acidity has decreased in all areas since 1989, resulting in increasing pH values in Sweden. The interannual variations of concentration and deposition of base cations and chloride are large and few general trends can be seen during 1983-1997. Time trends of four heavy metals in

  4. Anomalies in mineralization of low concentrations of organic compounds in lake water and sewage.

    OpenAIRE

    1986-01-01

    The rates of mineralization of nitrilotriacetic acid (NTA), 2,4-dichlorophenoxyacetic acid (2,4-D), p-nitrophenol, aniline, and isopropyl N-phenylcarbamate (IPC) at one or more concentrations ranging from 100 pg/ml to 1.0 microgram/ml were proportional to chemical concentrations in samples of three lakes. The rates at 100 pg of NTA, 2,4-D, p-nitrophenol, and aniline per ml in samples of one or more lakes were less than predicted, assuming the rates were linearly related to the concentration. ...

  5. Characterization of the Sources and Concentrations of Formaldehyde and other volatile organic compounds in four new manufactured houses

    Energy Technology Data Exchange (ETDEWEB)

    Hodgson, A.T.; Beal, D.; Chandra, S.

    1998-09-01

    The concentrations of formaldehyde, 52 individual volatile organic compounds (VOCs) and total VOCs (TVOC) were measured in four new manufactured houses on three occasions over a period of approximately nine months following completion of their construction. The houses were furnished, but unoccupied, model homes produced by a single U.S. manufacturer. Several of the houses incorporated interior finish materials with lower VOC emissions than standard materials. One house had a modified ventilation system. Ventilation rates were measured concurrently with the collection of air samples. A steady-state mass-balance model was used to calculate the area-specific emission rates of the target compounds and TVOC. The emissions of formaldehyde and VOCs from a specimen of plywood used as the floor sheeting were additionally quantified. The median formaldehyde concentration in the four houses was 37 parts-per-billion ( ppb). The formaldehyde concentrations were all less than the most restrictive guideline for this compound of 50 ppb. The concentrations of many of the target VOCs were low. Thirty-one of the VOCs had median concentrations that were at or below 1 ppb. Seven of the compounds were among the most abundant VOCs in all four houses. These compounds were alpha-pinene, beta-pinene, 3-carene, ethylene glycol, hexanal, 2-butanone, and acetic acid. The concentrations of the aldehydes, hexanal, octanal and nonanal, in the four houses were either near or exceeded their respective odor thresholds. The concentrations of acetic acid increased with time. In the final sampling period, the odor threshold for acetic acid was exceeded in all of the houses. The range of TVOC concentrations in the four houses was 0.8 to 3 mg m{sup -3}, with a median value of 1.6 mg m{sup -3}. These concentrations were somewhat lower than TVOC concentrations previously measured in several new site-built houses, and the median concentration was only about twice the typical value for existing residences

  6. Homogenization of a nonlinear degenerate parabolic equation

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    The homogenization of one kind of nonlinear parabolic equation is studied. The weak convergence and corrector results are obtained by combining carefully the compactness method and two-scale convergence method in the homogenization theory.

  7. Reflective Properties of a Parabolic Mirror.

    Science.gov (United States)

    Ramsey, Gordon P.

    1991-01-01

    An incident light ray parallel to the optical axis of a parabolic mirror will be reflected at the focal point and vice versa. Presents a mathematical proof that uses calculus, algebra, and geometry to prove this reflective property. (MDH)

  8. POSITIVE EQUILIBRIUM SOLUTIONS OF SEMILINEAR PARABOLIC EQUATIONS

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    The author studies semilinear parabolic equations with initial and periodic boundary value conditions. In the presence of non-well-ordered sub- and super-solutions:"subsolution (≤) supersolution", the existence and stability/instability of equilibrium solutions are obtained.

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

    Science.gov (United States)

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

    2014-11-01

    Pulse electron paramagnetic resonance imaging (Pulse EPRI) is a robust method for noninvasively measuring local oxygen concentrations in vivo. For 3D tomographic EPRI, the most commonly used reconstruction algorithm is filtered back projection (FBP), in which the parabolic filtration process strongly influences image quality. In this work, we designed and compared 7 parabolic filtration methods to reconstruct both simulated and real phantoms. To evaluate these methods, we designed 3 error criteria and 1 spatial resolution criterion. It was determined that the 2 point derivative filtration method and the two-ramp-filter method have unavoidable negative effects resulting in diminished spatial resolution and increased artifacts respectively. For the noiseless phantom the rectangular-window parabolic filtration method and sinc-window parabolic filtration method were found to be optimal, providing high spatial resolution and small errors. In the presence of noise, the 3 point derivative method and Hamming-window parabolic filtration method resulted in the best compromise between low image noise and high spatial resolution. The 3 point derivative method is faster than Hamming-window parabolic filtration method, so we conclude that the 3 point derivative method is optimal for 3D FBP. Copyright © 2014. Published by Elsevier Inc.

  10. Volatile Organic Compound Concentrations and Emission Rates in New Manufactured and Site-Built Houses

    Energy Technology Data Exchange (ETDEWEB)

    Armin Rudd

    2008-10-30

    This study was conducted with the primary objective of characterizing and comparing the airborne concentrations and the emission rates of total VOCs and selected individual VOCs, including formaldehyde, among a limited number of new manufactured and site-built houses.

  11. Amines and amine-related compounds in surface waters: a review of sources, concentrations and aquatic toxicity.

    Science.gov (United States)

    Poste, Amanda E; Grung, Merete; Wright, Richard F

    2014-05-15

    This review compiles available information on the concentrations, sources, fate and toxicity of amines and amine-related compounds in surface waters, including rivers, lakes, reservoirs, wetlands and seawater. There is a strong need for this information, especially given the emergence of amine-based post-combustion CO2 capture technologies, which may represent a new and significant source of amines to the environment. We identify a broad range of anthropogenic and natural sources of amines, nitrosamines and nitramines to the aquatic environment, and identify some key fate and degradation pathways of these compounds. There were very few data available on amines in surface waters, with reported concentrations often below detection and only rarely exceeding 10 μg/L. Reported concentrations for seawater and reservoirs were below detection or very low, while for lakes and rivers, concentrations spanned several orders of magnitude. The most prevalent and commonly detected amines were methylamine (MA), dimethylamine (DMA), ethylamine (EA), diethylamine (DEA) and monoethanolamine (MEAT). The paucity of data may reflect the analytical challenges posed by determination of amines in complex environmental matrices at ambient levels. We provide an overview of available aquatic toxicological data for amines and conclude that at current environmental concentrations, amines are not likely to be of toxicological concern to the aquatic environment, however, the potential for amines to act as precursors in the formation of nitrosamines and nitramines may represent a risk of contamination of drinking water supplies by these often carcinogenic compounds. More research on the prevalence and toxicity of amines, nitrosamines and nitramines in natural waters is necessary before the environmental impact of new point sources from carbon capture facilities can be adequately quantified.

  12. Utilization of internal standard response factors to estimate the concentration of organic compounds leached from pharmaceutical packaging systems and application of such estimated concentrations to safety assessment.

    Science.gov (United States)

    Jenke, Dennis; Odufu, Alex

    2012-03-01

    Substances from packaging systems that are leached into packaged medical products may have a safety impact on patients to whom such medical products are administered. The potential safety impact depends on the identity and concentration of the leached substances. The concentration above which a leachable must be identified in order to assess its safety impact is frequently estimated using an internal standard to "calibrate" the analytical response of a chromatographic system. Such an estimate is accurate to the extent that the responses of the internal standard and leachables are similar. To establish the accuracy of the internal standard approach, a database of gas chromatography-flame ionization detection (GC-FID) and gas chromatography-mass spectrometry (GC-MS) responses was generated for thirty-eight leachables and eight internal standard candidates. Although the FID and MS responses of many of the leachables and internal standards fell within a narrow band, acidic and basic compounds produced responses that were discernibly different from those of neutral analytes. While most of the internal standards were suited for concentration estimation, three of the candidates, dimethylphthalate, triphenylphosphate and 4,4-dibromobiphenyl, produced the smallest mean error in estimated concentration for the analytes examined. As the FID and MS responses were linear, internal standards could be used to estimate leachables concentrations even when the difference in leachable versus internal standard concentrations was as great as a factor of 25. A multiplier may be appropriate to adjust an estimated concentration to its greatest possible value, and it is this value that is used to convert an estimated Analytical Evaluation Threshold (AET) into a working or final AET.

  13. 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

  14. Examining the response of larch needle carbohydrates to climate using compound-specific δ13C and concentration analyses

    Science.gov (United States)

    Rinne, Katja T.; Saurer, Matthias; Kirdyanov, Alexander V.; Bryukhanova, Marina V.; Prokushkin, Anatoly S.; Churakova Sidorova, Olga V.; Siegwolf, Rolf T. W.

    2016-04-01

    Little is known about the dynamics of concentrations and carbon isotope ratios of individual carbohydrates in leaves in response to climatic and physiological factors. Improved knowledge of the isotopic ratio in sugars will enhance our understanding of the tree ring isotope ratio and will help to decipher environmental conditions in retrospect more reliably. Carbohydrate samples from larch (Larix gmelinii) needles of two sites in the continuous permafrost zone of Siberia with differing growth conditions were analysed with the Compound-Specific Isotope Analysis (CSIA). We compared concentrations and carbon isotope values (δ13C) of sucrose, fructose, glucose and pinitol combined with phenological data. The results for the variability of the needle carbohydrates show high dynamics with distinct seasonal characteristics between and within the studied years with a clear link to the climatic conditions, particularly vapour pressure deficit. Compound-specific differences in δ13C values as a response to climate were detected. The δ13C of pinitol, which contributes up to 50% of total soluble carbohydrates, was almost invariant during the whole growing season. Our study provides the first in-depth characterization of compound-specific needle carbohydrate isotope variability, identifies involved mechanisms and shows the potential of such results for linking tree physiological responses to different climatic conditions.

  15. Changes in guava (Psidium guajava L. var. Paluma nectar volatile compounds concentration due to thermal processing and storage

    Directory of Open Access Journals (Sweden)

    Maria Ivaneide Coutinho Correa

    2010-12-01

    Full Text Available Guava nectars were formulated for approximately 10, 12, or 14 ºBrix, with 40% guava pulp. Sodium benzoate, 500 mg.kg-1 was used as preservative. The Brix value was adjusted with saturated sucrose syrup. The guava nectar was pasteurized (85 ºC/42 seconds in tubular heat exchanger and then hot filled in 500 mL white glass bottles. The products were stored either at room temperature (25 ± 5 ºC or refrigerated (5 ± 2 ºC under fluorescent light exposure and analyzed on the day after processing (time zero and also 40, 80, and 120 days of storage. Eight compounds were identified and quantified by Gas Chromatography (GC -Mass Spectrometry (MS: hexanal, (E-hex-2-enal, 1-hexenol, (Z-hex-3-enol, (Z-hex-3-enyl acetate, phenyl-3-propyl acetate, cinnamyl acetate, and acetic acid. There was no significant effect of thermal treatment on the volatile compound concentrations, except for a significant decrease (p = 0.0001 in hexanal and (Z-hex-3-enyl acetate (p = 0.0029. As for the storage time, there was a much greater decrease in the esters contents, such as (Z-hex-3-enyl and phenyl-3-propyl acetates. Cinnamyl acetate had the greatest decrease over storage time. Refrigeration was better than room temperature for guava nectar volatile compounds stability over storage time, mainly for esters compounds, which are important for the product aroma and flavor

  16. Fluxes and concentrations of volatile organic compounds from a South-East Asian tropical rainforest

    Directory of Open Access Journals (Sweden)

    B. Langford

    2010-09-01

    Full Text Available As part of the OP3 field study of rainforest atmospheric chemistry, above-canopy fluxes of isoprene, monoterpenes and oxygenated volatile organic compounds were made by virtual disjunct eddy covariance from a South-East Asian tropical rainforest in Malaysia. Approximately 500 hours of flux data were collected over 48 days in April–May and June–July 2008. Isoprene was the dominant non-methane hydrocarbon emitted from the forest, accounting for 80% (as carbon of the measured emission of reactive carbon fluxes. Total monoterpene emissions accounted for 18% of the measured reactive carbon flux. There was no evidence for nocturnal monoterpene emissions and during the day their flux rate was dependent on both light and temperature. The oxygenated compounds, including methanol, acetone and acetaldehyde, contributed less than 2% of the total measured reactive carbon flux. The sum of the VOC fluxes measured represents a 0.4% loss of daytime assimilated carbon by the canopy, but atmospheric chemistry box modelling suggests that most (90% of this reactive carbon is returned back to the canopy by wet and dry deposition following chemical transformation. The emission rates of isoprene and monoterpenes, normalised to 30 °C and 1000 μmol m−2 s−1 PAR, were 1.6 mg m−2 h−1 and 0.46mg m−2 h−1 respectively, which was 4 and 1.8 times lower respectively than the default value for tropical forests in the widely-used MEGAN model of biogenic VOC emissions. This highlights the need for more direct canopy-scale flux measurements of VOCs from the world's tropical forests.

  17. Effects of low concentration biodiesel blends application on modern passenger cars. Part 2: impact on carbonyl compound emissions.

    Science.gov (United States)

    Fontaras, Georgios; Karavalakis, Georgios; Kousoulidou, Marina; Ntziachristos, Leonidas; Bakeas, Evangelos; Stournas, Stamoulis; Samaras, Zissis

    2010-07-01

    Today in most European member states diesel contains up to 5% vol biodiesel. Since blending is expected to increase to 10% vol, the question arises, how this higher mixing ratio will affect tailpipe emissions particularly those linked to adverse health effects. This paper focuses on the impact of biodiesel on carbonyl compound emissions, attempting also to identify possible relationship between biodiesel feedstock and emissions. The blends were produced from five different feedstocks, commonly used in Europe. Measurements were conducted on a Euro 3 common-rail passenger car over various driving cycles. Results indicate that generally the use of biodiesel at low concentrations has a minor effect on carbonyl compound emissions. However, certain biodiesels resulted in significant increases while others led to decreases. Biodiesels associated with increases were those derived from rapeseed oil (approx. 200%) and palm oil (approx. 180%), with the highest average increases observed at formaldehyde and acroleine/acetone.

  18. Development of sheet molding compound solar collectors with molded-in silvered glass reflective surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Champion, R. L.; Allred, R. E.

    1980-12-01

    The reflecting concentrator of a parabolic trough solar collector system comprises approximately 40% of initial system cost. The parabolic concentrator structure is also the most influential component in determining overall system efficiency. Parabolic test moldings have been fabricated from a general purpose sheet molding compound with flat chemically strengthened glass, flat annealed glass, and thermally formed glass. The test panel configuration was a 1.22 m x 0.61 m, 45/sup 0/ rim angle (0.762 m focal length) parabola. Attempts to mold with annealed sheet glass (1 mm thick) and thermally formed glass (1.25 mm thick) were unsuccessful; only the chemically strengthened glass (1.25 mm thick) was strong enough to survive molding pressures. Because of the mismatch in thermal expansion between glass and sheet molding compound, the as-molded panels contained a sizeable residual stress. The results are given of dimensional changes taking place in the panels under accelerated thermal cycling and outdoor aging conditions; these results are compared to an analytical model of the laminate. In addition, the sheet molding compound has been examined for thermomechanical properties and flow behavior in the rib sections. Results indicated that lowering the thermal expansion coefficient of the sheet molding compound through material modifications would produce a more stable structure.

  19. Large mass self-similar solutions of the parabolic-parabolic Keller-Segel model of chemotaxis.

    Science.gov (United States)

    Biler, Piotr; Corrias, Lucilla; Dolbeault, Jean

    2011-07-01

    In two space dimensions, the parabolic-parabolic Keller-Segel system shares many properties with the parabolic-elliptic Keller-Segel system. In particular, solutions globally exist in both cases as long as their mass is less than a critical threshold M(c). However, this threshold is not as clear in the parabolic-parabolic case as it is in the parabolic-elliptic case, in which solutions with mass above M(c) always blow up. Here we study forward self-similar solutions of the parabolic-parabolic Keller-Segel system and prove that, in some cases, such solutions globally exist even if their total mass is above M(c), which is forbidden in the parabolic-elliptic case.

  20. Piecewise-Planar Parabolic Reflectarray Antenna

    Science.gov (United States)

    Hodges, Richard; Zawadzki, Mark

    2009-01-01

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

  1. Describing Quadratic Cremer Point Polynomials by Parabolic Perturbations

    DEFF Research Database (Denmark)

    Sørensen, Dan Erik Krarup

    1996-01-01

    .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...... external ray accumulating the Cremer point, but having in itsimpression both the Cremer point and its other preimage. We think of the Julia setas containing a "topologists single comb".By tuning, similar results hold on the boundary of any hyperbolic component of theMandelbrot set....

  2. Volatile organic compounds in urban atmospheres: Long-term measurements of ambient air concentrations in differently loaded regions of Leipzig

    Energy Technology Data Exchange (ETDEWEB)

    Knobloch, T.; Asperger, A.; Engewald, W. [University of Leipzig, Institute of Analytical Chemistry, Leipzig (Germany)

    1997-09-01

    For the comprehensive characterization of ambient air concentrations of a broad spectrum of volatile organic compounds (VOCs) an analytical method is described, consisting of adsorptive enrichment, thermal desorption without cryofocusing, and capillary gas chromatographic separation. The method was applied during two-week measuring campaigns in winter and summer 1995, and in the winter of 1996. Long-term sampling was carried out at sampling points in residential areas in the suburbs and near the city center of Leipzig. About 70 VOCs - mainly hydrocarbons from propene to hexadecane - were identified both by GC-MS and chromatographic retention data and quantified after external calibration. Mean values of VOC concentrations obtained during the sampling periods are reported and discussed with regard to the topographical location of the sampling points in the Leipzig area, seasonal variations, and possible emission sources. (orig.) With 7 figs., 3 tabs., 18 refs.

  3. Field measurements of perceived air quality and concentration of volatile organic compounds in four offices of the university building

    DEFF Research Database (Denmark)

    Kolarik, Jakub; Toftum, Jørn; Kabrhel, M.

    2015-01-01

    Field measurements of perceived air quality were conducted in four refurbished offices at the Czech Technical University in Prague. The offices were refurbished as part of the research project Clear-up to serve as a field test facility. The present paper describes measurements conducted...... to investigate the perceived air quality, sensory pollution load and concentration of Volatile Organic Compounds (VOCs) in the offices. As the refurbishment comprised also installation of demand controlled ventilation (DCV), its influence on the perceived air quality was also tested. Measurements comprised...... the assessments of perceived air quality and objective measurements of operative temperature, relative humidity, CO2 and VOCs concentrations. Results showed that the mean sensory pollution load in unoccupied offices was 0.09 ± 0.01 olf/m2 (mean ± SEM). This falls into the category of a low-polluting building...

  4. Detection of Volatile Organic Compounds by Self-assembled Monolayer Coated Sensor Array with Concentration-independent Fingerprints

    Science.gov (United States)

    Chang, Ye; Tang, Ning; Qu, Hemi; Liu, Jing; Zhang, Daihua; Zhang, Hao; Pang, Wei; Duan, Xuexin

    2016-04-01

    In this paper, we have modeled and analyzed affinities and kinetics of volatile organic compounds (VOCs) adsorption (and desorption) on various surface chemical groups using multiple self-assembled monolayers (SAMs) functionalized film bulk acoustic resonator (FBAR) array. The high-frequency and micro-scale resonator provides improved sensitivity in the detections of VOCs at trace levels. With the study of affinities and kinetics, three concentration-independent intrinsic parameters (monolayer adsorption capacity, adsorption energy constant and desorption rate) of gas-surface interactions are obtained to contribute to a multi-parameter fingerprint library of VOC analytes. Effects of functional group’s properties on gas-surface interactions are also discussed. The proposed sensor array with concentration-independent fingerprint library shows potential as a portable electronic nose (e-nose) system for VOCs discrimination and gas-sensitive materials selections.

  5. Red blood cells sensitivity to oxidative stress in the presence of low concentrations of uranium compound

    Energy Technology Data Exchange (ETDEWEB)

    Shevchenko, O.G. [Institute of Biology, Komi Scientific Centre, Ural Branch of Russian Academy of Sciences, 167982, Syktyvkar (Russian Federation)

    2014-07-01

    Uranium is a natural radioactive element widespread in biosphere. There are a few works that examined cellular and molecular mechanisms of uranium toxicity. Red blood cells are classical model to investigate toxicity mechanisms on cell membrane system. The aim of present work is to study the effect of uranyl ion in nano-molar concentrations on erythrocytes sensitivity (in vitro) to factors provoking acute oxidative stress. Uranyl ions were added to suspension of mice red blood cells in PBS as UO{sub 2}Cl{sub 2} solution. Samples were incubated in a thermostatic shaker at 37 deg. C during 3-5 hours. Than acute oxidative stress was induced by H{sub 2}O{sub 2} (0.9 mM) or AAPH (5 mM) solutions. Destabilization of the membrane was induced by nonionic detergent Triton X-100. The hemolysis degree and the content of LPO secondary products reacting with 2-thiobarbituric acid in the incubation mixture were determined spectrophotometrically. The ratio of hemoglobin various forms (oxyHb, metHb and ferrylHb) was calculated taking into account extinction coefficients. It was shown that uranyl chloride enhances cell sensitivity to nonionic detergent Triton X-100 effects, indicating alterations of membrane acyl chain order due to contact with the radionuclide ions. Uranium exposure also caused an increase in the cell sensitivity to the AAPH effects, resulted in a decrease in red cell survival rate, a sharp increase in accumulation of hemoglobin oxidation products and a slight increase in the concentration of LPO secondary products. Thus, uranyl ions change physicochemical properties of the erythrocyte membranes that resulted in increased sensitivity to effects of peroxyl radicals formed by thermal decomposition of AAPH. On the contrary, use of another source of free radicals - H{sub 2}O{sub 2} - after uranyl ions exposure resulted in marked decrease of oxidative hemolysis, inhibition of LPO and hemoglobin oxidation. Since the uranium chemical properties similar to properties of

  6. Ambient Concentrations and Emissions of a Comprehensive Suite of Volatile Organic Compounds at the CalNex-Bakersfield Supersite

    Science.gov (United States)

    Gentner, D. R.; Goldstein, A. H.

    2010-12-01

    Ambient concentrations of ~250 Volatile Organic Compounds (VOCs) were measured hourly via in-situ gas chromatography at the Bakersfield, CA supersite in May & June 2010 as part of the California at the Nexus between Air Quality and Climate Change (CalNex) Experiment. Measurements included anthropogenic and biogenic VOCs containing 1 to 17 carbon atoms and a variety of functional groups (e.g. aldehydes, ketones, alcohols, halogens, sulfur, & nitrogen). We quantified a very broad range of primary gas-phase organics that lead to the formation of secondary organic aerosol (SOA) and tropospheric ozone, and we also observed many gas-phase products of VOC photooxidation. Many of the observed VOCs are volatile and have been measured previously, but in this experiment we tailored the instrumentation to also measure compounds in the intermediate volatility range, which are thought to contribute significantly to SOA and have rarely or never been reported from in-situ measurements. Among the observed gas-phase VOCs with lower volatility are PAHs (e.g. naphthalene, methylnaphthalenes, and dimethylnaphthalenes), alkanes up to 17 carbon atoms, aromatics and cycloalkanes with multiple alkyl groups, and functionalized VOCs with lower volatility. Analyses of the diurnal variability, covariance between compounds, weekday/weekend differences, and statistical analyses for source apportionment such as Positive Matrix Factorization (PMF) will be utilized to establish the major sources of these compounds and estimate regional emissions. Our VOC data provides excellent context for analysis of the broad array of gas and particle phase measurements during CalNex2010, which will be used to elucidate the chemistry leading to formation of SOA and tropospheric ozone in this polluted region of California with diverse urban, industrial, agricultural, and natural emission sources.

  7. Random perturbations of nonlinear parabolic systems

    CERN Document Server

    Beck, Lisa

    2011-01-01

    Several aspects of regularity theory for parabolic systems are investigated under the effect of random perturbations. The deterministic theory, when strict parabolicity is assumed, presents both classes of systems where all weak solutions are in fact more regular, and examples of systems with weak solutions which develop singularities in finite time. Our main result is the extension of a regularity result due to Kalita to the stochastic case. Concerning the examples with singular solutions (outside the setting of Kalita's regularity result), we do not know whether stochastic noise may prevent the emergence of singularities, as it happens for easier PDEs. We can only prove that, for a linear stochastic parabolic system with coefficients outside the previous regularity theory, the expected value of the solution is not singular.

  8. Parabolic flight as a spaceflight analog.

    Science.gov (United States)

    Shelhamer, Mark

    2016-06-15

    Ground-based analog facilities have had wide use in mimicking some of the features of spaceflight in a more-controlled and less-expensive manner. One such analog is parabolic flight, in which an aircraft flies repeated parabolic trajectories that provide short-duration periods of free fall (0 g) alternating with high-g pullout or recovery phases. Parabolic flight is unique in being able to provide true 0 g in a ground-based facility. Accordingly, it lends itself well to the investigation of specific areas of human spaceflight that can benefit from this capability, which predominantly includes neurovestibular effects, but also others such as human factors, locomotion, and medical procedures. Applications to research in artificial gravity and to effects likely to occur in upcoming commercial suborbital flights are also possible. Copyright © 2016 the American Physiological Society.

  9. Parabolic non-diffracting beams: geometrical approach

    Science.gov (United States)

    Sosa-Sánchez, Citlalli Teresa; Silva-Ortigoza, Gilberto; Alejandro Juárez-Reyes, Salvador; de Jesús Cabrera-Rosas, Omar; Espíndola-Ramos, Ernesto; Julián-Macías, Israel; Ortega-Vidals, Paula

    2017-08-01

    The aim of this work is to present a geometrical characterization of parabolic non-diffracting beams. To this end, we compute the corresponding angular spectrum of the separable non-diffracting parabolic beams in order to determine the one-parameter family of solutions of the eikonal equation associated with this type of beam. Using this information, we compute the corresponding wavefronts and caustic, and find that qualitatively the caustic corresponds to the maximum of the intensity pattern and the wavefronts are deformations of conical surfaces.

  10. Controllable parabolic-cylinder optical rogue wave.

    Science.gov (United States)

    Zhong, Wei-Ping; Chen, Lang; Belić, Milivoj; Petrović, Nikola

    2014-10-01

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

  11. Asymptotical Properties for Parabolic Systems of Neutral Type

    Institute of Scientific and Technical Information of China (English)

    CUI Bao-tong; HAN Mao-an

    2005-01-01

    Asymptotical properties for the solutions of neutral parabolic systems with Robin boundary conditions were analyzed by using the inequality analysis. The oscillations problems for the neutral parabolic systems were considered and some oscillation criteria for the systems were established.

  12. Predicted concentrations in new relocatable classrooms of volatile organic compounds emitted from standard and alternate interior finish materials

    Energy Technology Data Exchange (ETDEWEB)

    Hodgson, Alfred T.; Fisk, William J.; Shendell, Derek G.; Apte, Michael G.

    2001-07-01

    Relocatable classrooms (RCs) are widely employed by California school districts to satisfy rapidly expanding space requirements due to population growth and class size reduction policies. There is public concern regarding indoor environmental quality (IEQ) in schools, particularly in RCs, but very little data to support or dispel these concerns. Several studies are investigating various aspects of IEQ in California schools. This laboratory-based study focused on evaluating the emissions of toxic and/or odorous volatile organic compounds (VOCs), including formaldehyde and acetaldehyde, from materials used to finish the interiors of new RCs. Furthermore, the study implemented a procedure for VOC source reduction by testing and selecting lower-emitting materials as substitutes for standard materials. In total, 17 standard and alternate floor coverings, wall panels and ceiling panels were quantitatively tested for emissions of VOCs using smallscale environmental chambers. Working with the largest northern California manufacturer of conventional RCs and two school districts, specifications were developed for four new RCs to be produced in early summer 2001. Two of these will be predominantly finished with standard materials. Alternate carpet systems, an alternate wall panel covering and an alternate ceiling panel were selected for the two other RCs based on the results of the laboratory study and considerations of cost and anticipated performance and maintenance. Particular emphasis was placed on reducing the concentrations of VOCs on California agency lists of toxic compounds. Indoor concentrations of toxic and odorous VOCs were estimated for the four classrooms by mass balance using the measured VOC emission factors, exposed surface areas of the materials in the RCs, and three ventilation rate scenarios. Results indicate that reductions in the concentrations of formaldehyde, acetaldehyde phenol, di(ethylene glycol) butyl ether, vinyl acetate, 1,2,4-trimethylbenzene

  13. Regional variability in bed-sediment concentrations of wastewater compounds, hormones and PAHs for portions of coastal New York and New Jersey impacted by hurricane Sandy

    Science.gov (United States)

    Phillips, Patrick; Gibson, Cathy A; Fisher, Shawn C.; Fisher, Irene; Reilly, Timothy J.; Smalling, Kelly L.; Romanok, Kristin M.; Foreman, William T.; ReVello, Rhiannon C.; Focazio, Michael J.; Jones, Daniel K.

    2016-01-01

    Bed sediment samples from 79 coastal New York and New Jersey, USA sites were analyzed for 75 compounds including wastewater associated contaminants, PAHs, and other organic compounds to assess the post-Hurricane Sandy distribution of organic contaminants among six regions. These results provide the first assessment of wastewater compounds, hormones, and PAHs in bed sediment for this region. Concentrations of most wastewater contaminants and PAHs were highest in the most developed region (Upper Harbor/Newark Bay, UHNB) and reflected the wastewater inputs to this area. Although the lack of pre-Hurricane Sandy data for most of these compounds make it impossible to assess the effect of the storm on wastewater contaminant concentrations, PAH concentrations in the UHNB region reflect pre-Hurricane Sandy conditions in this region. Lower hormone concentrations than predicted by the total organic carbon relation occurred in UHNB samples, suggesting that hormones are being degraded in the UHNB region.

  14. Probability of Elevated Volatile Organic Compound (VOC) Concentrations in Groundwater in the Eagle River Watershed Valley-Fill Aquifer, Eagle County, North-Central Colorado, 2006-2007

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This raster data set delineates the predicted probability of elevated volatile organic compound (VOC) concentrations in groundwater in the Eagle River watershed...

  15. Using performance reference compounds in polyethylene passive samplers to deduce sediment porewater concentrations for numerous target chemicals.

    Science.gov (United States)

    Fernandez, Loretta A; Harvey, Charles F; Gschwend, Philip M

    2009-12-01

    Polymeric passive samplers are useful for assessing hydrophobic organic chemical contamination in sediment beds. Here, an improved method is described for measuring concentrations of contaminants in porewater by using performance reference compounds (deuterated phenanthrene, pyrene, and chrysene) to calibrate sampler/site-specific mass transfer behavior. The method employs a one-dimensional diffusion model of chemical exchange between a polymer sheet of finite thickness and an unmixed sediment bed. The model is parametrized by diffusivities and partition coefficients for both the sampler and sediment. This method was applied to estimate porewater concentrations for seventeen PAHs from polymeric samplers deployed for 3-10 days in homogenized sediment from a coal-tar contaminated site. The accuracy of the method was verified by comparing the passive sampler results to concentrations measured through liquid-liquid extraction of physically separated porewaters, with corrections for sorption to colloidal organic carbon. The measurements made using the two methods matched within about a factor of 2.0 (+/-0.9) for the 17 target PAHs.

  16. In Vitro Evaluation of Sub-Lethal Concentrations of Plant-Derived Antifungal Compounds on FUSARIA Growth and Mycotoxin Production

    Directory of Open Access Journals (Sweden)

    Caterina Morcia

    2017-07-01

    Full Text Available Phytopathogenic fungi can lead to significant cereal yield losses, also producing mycotoxins dangerous for human and animal health. The fungal control based on the use of synthetic fungicides can be complemented by "green" methods for crop protection, based on the use of natural products. In this frame, the antifungal activities of bergamot and lemon essential oils and of five natural compounds recurrent in essential oils (citronellal, citral, cinnamaldehyde, cuminaldehyde and limonene have been evaluated against three species of mycotoxigenic fungi (Fusarium sporotrichioides, F. graminearum and F. langsethiae responsible for Fusarium Head Blight in small-grain cereals. The natural products concentrations effective for reducing or inhibiting the in vitro fungal growth were determined for each fungal species and the following scale of potency was found: cinnamaldehyde > cuminaldehyde > citral > citronellal > bergamot oil > limonene > lemon oil. Moreover, the in vitro mycotoxin productions of the three Fusaria strains exposed to sub-lethal concentrations of the seven products was evaluated. The three fungal species showed variability in response to the treatments, both in terms of inhibition of mycelial growth and in terms of modulation of mycotoxin production that can be enhanced by sub-lethal concentrations of some natural products. This last finding must be taken into account in the frame of an open field application of some plant-derived fungicides.

  17. Investigation of indoor air volatile organic compounds concentration levels in dental settings and some related methodological issues.

    Science.gov (United States)

    Santarsiero, Anna; Fuselli, Sergio; Piermattei, Alessandro; Morlino, Roberta; De Blasio, Giorgia; De Felice, Marco; Ortolani, Emanuela

    2009-01-01

    The assessment of indoor air volatile organic compounds (VOCs) concentration levels in dental settings has a big health relevance for the potentially massive occupational exposure to a lot of diverse contaminants. The comparison of the VOCs profile relative to indoor conditions and to the corresponding outdoor concentrations, as well as the discovery of possible correlations between specific dental activities and VOCs concentration variations are of utmost importance for offering a reliable characterization of risk for dentists and dental staff health. In this study we review the most relevant environmental studies addressing the VOCs contamination level in dental settings. We analyze the methodological problems this kind of study must face and we report preliminary results of an indoor air investigation, carried out at dental hospital in Italy, the "Ospedale odontoiatrico George Eastman" of Rome, in which general lines for the analysis of dental settings in environmental terms are sketched. The aim of this work is to identify the kind of problems a typical enclosed (non-industrial) environment indoor air investigation has to cope with by means of the analysis of a case study.

  18. A NEWTON MULTIGRID METHOD FOR QUASILINEAR PARABOLIC EQUATIONS

    Institute of Scientific and Technical Information of China (English)

    YU Xijun

    2005-01-01

    A combination of the classical Newton Method and the multigrid method, i.e.,a Newton multigrid method is given for solving quasilinear parabolic equations discretized by finite elements. The convergence of the algorithm is obtained for only one step Newton iteration per level. The asymptotically computational cost for quasilinear parabolic problems is O(NNk) similar to multigrid method for linear parabolic problems.

  19. On a Parabolic-Elliptic system with chemotaxis and logistic type growth

    Science.gov (United States)

    Galakhov, Evgeny; Salieva, Olga; Tello, J. Ignacio

    2016-10-01

    We consider a nonlinear PDEs system of two equations of Parabolic-Elliptic type with chemotactic terms. The system models the movement of a biological population "u" towards a higher concentration of a chemical agent "w" in a bounded and regular domain Ω ⊂RN for arbitrary N ∈ N. After normalization, the system is as follows

  20. Effects of sugar concentration processes in grapes and wine aging on aroma compounds of sweet wines—a review.

    Science.gov (United States)

    Reboredo-Rodríguez, Patricia; González-Barreiro, Carmen; Rial-Otero, Raquel; Cancho-Grande, Beatriz; Simal-Gándara, Jesús

    2015-01-01

    Dessert sweet wines from Europe and North America are described in this review from two points of view: both their aroma profile and also their sensorial description. There are growing literature data about the chemical composition and sensory properties of these wines. Wines were grouped according to the production method (concentration of sugars in grapes) and to the aging process of wine (oxidative, biological, or a combination of both and aging in the bottle). It was found that wines natively sweets and wines fortified with liquors differ in their volatile compounds. Sensory properties of these wines include those of dried fruit (raisins), red berries, honey, chocolate and vanilla, which is contributing to their growing sales. However, there is still a need for scientific research on the understanding of the mechanisms for wine flavor enhancement.

  1. Impact of industrial production and packaging processes on the concentration of per- and polyfluorinated compounds in milk and dairy products.

    Science.gov (United States)

    Still, Mona; Schlummer, Martin; Gruber, Ludwig; Fiedler, Dominik; Wolz, Gerd

    2013-09-25

    Perfluorinated alkylated compounds (PFAA) have been identified in milk and dairy products at sub ppb levels, however, knowledge on the impact of industrial milk processing on PFAA levels is rare. This study examined industrial milk processing first by analytical screening of products of a cooperating dairy, which varied in kind and number of processing steps. Second, amounts of PFAA in raw milk, cream, skim milk, butter milk, and butter were mass balanced in industrial production. For migration testing, unpacked butter was sampled from the production and exposed to original packaging at 5 °C for 45 days. Screening identified dairy products with high fat contents to bear higher loads of PFAA. The mass balance of butter production revealed a significant impact of phase separation processes on concentrations in fat rich and aqueous phases. Storage of butter in packaging coated with a fluorinated polymer increased butter levels of both PFAA and FTOH.

  2. Chernoff's distribution and parabolic partial differential equations

    NARCIS (Netherlands)

    P. Groeneboom; S.P. Lalley; N.M. Temme (Nico)

    2013-01-01

    textabstractWe give an alternative route to the derivation of the distribution of the maximum and the location of the maximum of one-sided and two-sided Brownian motion with a negative parabolic drift, using the Feynman-Kac formula with stopping times. The derivation also uses an interesting

  3. Orbit Connections in a Parabolic Equation.

    Science.gov (United States)

    1983-04-01

    Departamento de Matematica , 13560, Slo Carlos, S.P. Brasil. This research has been supported in part by CAPES-qoordena~io de Aperfeiqoamento de Pessoal...de Nivel Superior , Brasilia, D.F., Brasil under contract Proc. #3056/78. 1k ORBIT CONNECTIONS IN A PARABOLIC EQUATION by Jack K. Hale and Arnaldo S

  4. Stokes' theorem, volume growth and parabolicity

    CERN Document Server

    Valtorta, Daniele

    2010-01-01

    We present some new Stokes'type theorems on complete non-compact manifolds that extend, in different directions, previous work by Gaffney and Karp and also the so called Kelvin-Nevanlinna-Royden criterion for (p-)parabolicity. Applications to comparison and uniqueness results involving the p-Laplacian are deduced.

  5. CONTINUOUS DEPENDENCE FOR A BACKWARD PARABOLIC PROBLEM

    Institute of Scientific and Technical Information of China (English)

    刘继军

    2003-01-01

    We consider a backward parabolic problem arising in the description of the behavior of the toroidal part of the magenetic field in a dynamo problem. In our backward time problem, the media parameters are spatial distributed and the boundary conditions are of the Robin type. For this ill-posed problem, we prove that the solution depends continuously on the initial-time geometry.

  6. Discontinuous mixed covolume methods for parabolic problems.

    Science.gov (United States)

    Zhu, Ailing; Jiang, Ziwen

    2014-01-01

    We present the semidiscrete and the backward Euler fully discrete discontinuous mixed covolume schemes for parabolic problems on triangular meshes. We give the error analysis of the discontinuous mixed covolume schemes and obtain optimal order error estimates in discontinuous H(div) and first-order error estimate in L(2).

  7. An Approximation of Ultra-Parabolic Equations

    Directory of Open Access Journals (Sweden)

    Allaberen Ashyralyev

    2012-01-01

    Full Text Available The first and second order of accuracy difference schemes for the approximate solution of the initial boundary value problem for ultra-parabolic equations are presented. Stability of these difference schemes is established. Theoretical results are supported by the result of numerical examples.

  8. ANISOTROPIC PARABOLIC EQUATIONS WITH MEASURE DATA

    Institute of Scientific and Technical Information of China (English)

    Li Fengquan; Zhao Huixiu

    2001-01-01

    In this paper, we prove the existence of solutions to anisotropic parabolic equations with right hand side term in the bounded Radon measure M(Q) and the initial condition in M(Ω) or in Lm space (with m "small").

  9. Chernoff's distribution and parabolic partial differential equations

    NARCIS (Netherlands)

    P. Groeneboom; S.P. Lalley; N.M. Temme (Nico)

    2013-01-01

    textabstractWe give an alternative route to the derivation of the distribution of the maximum and the location of the maximum of one-sided and two-sided Brownian motion with a negative parabolic drift, using the Feynman-Kac formula with stopping times. The derivation also uses an interesting relatio

  10. Exchange of reactive nitrogen compounds: concentrations and fluxes of total ammonium and total nitrate above a spruce canopy

    Directory of Open Access Journals (Sweden)

    V. Wolff

    2010-05-01

    Full Text Available Total ammonium (tot-NH4+ and total nitrate (tot-NO3 provide chemically conservative quantities in the measurement of surface exchange of reactive nitrogen compounds ammonia (NH3, particulate ammonium (NH4+, nitric acid (HNO3, and particulate nitrate (NO3, using the aerodynamic gradient method. Total fluxes were derived from concentration differences of total ammonium (NH3 and NH4+ and total nitrate (HNO3 and NO3 measured at two levels. Gaseous species and related particulate compounds were measured selectively, simultaneously and continuously above a spruce forest canopy in south-eastern Germany in summer 2007. Measurements were performed using a wet-chemical two-point gradient instrument, the GRAEGOR. Median concentrations of NH3, HNO3, NH4+, and NO3 were 0.57, 0.12, 0.76, and 0.48 μg m−3, respectively. Total ammonium and total nitrate fluxes showed large variations depending on meteorological conditions, with concentrations close to zero under humid and cool conditions and higher concentrations under dry conditions. Mean fluxes of total ammonium and total nitrate in September 2007 were directed towards the forest canopy and were −65.77 ng m−2 s−1 and −41.02 ng m−2 s−1 (in terms of nitrogen, respectively. Their deposition was controlled by aerodynamic resistances only, with very little influence of surface resistances. Including measurements of wet deposition and findings of former studies on occult deposition (fog water interception at the study site, the total N deposition in September 2007 was estimated to 5.86 kg ha−1.

  11. Exchange of reactive nitrogen compounds: concentrations and fluxes of total ammonium and total nitrate above a spruce forest canopy

    Directory of Open Access Journals (Sweden)

    V. Wolff

    2009-11-01

    Full Text Available Total ammonium (tot-NH4+ and total nitrate (tot-NO3 provide a chemically conservative quantity in the measurement of exchange processes of reactive nitrogen compounds ammonia (NH3, particulate ammonium (NH4+, nitric acid (HNO3, and particulate nitrate (NO3, using the aerodynamic gradient method. Total fluxes were derived from concentration differences of total ammonium (NH3 and NH4+ and total nitrate (HNO3 and NO3 measured at two levels. Gaseous species and related particulate compounds were measured selectively, simultaneously and continuously above a spruce forest canopy in south-eastern Germany in summer 2007. Measurements were performed using a wet-chemical two-point gradient instrument, the GRAEGOR. Median concentrations of NH3, HNO3, NH4, and NO3 were 0.57, 0.12, 0.76, and 0.48 μg m−3, respectively. Total ammonium and total nitrate fluxes showed large variations depending on meteorological conditions, with concentrations close to zero under humid and cool conditions and higher concentrations under dry conditions. Mean fluxes of total ammonium and total nitrate in September 2007 were directed towards the forest canopy and were −65.77 ng m−2 s−1 and −41.02 ng m−2 s−1 (in terms of nitrogen, respectively. Their deposition was controlled by aerodynamic resistances only, with very little influence of surface resistances. Including measurements of wet deposition and findings of former studies at the study site on occult deposition (fog water interception, the total N deposition in September 2007 was estimated to 5.86 kg ha−1.

  12. Rate of change in concentration of organic compounds and nutrients in municipal and dairy wastewater treated in full technical SBR scale

    Directory of Open Access Journals (Sweden)

    Struk-Sokolowska Joanna

    2017-01-01

    Full Text Available Municipal WWTP often receive the industrial wastewater, including dairy sewage. The problem of sewage treatment from this sector of economy is not completely solved, especially in plants of medium and small milk processing capacity. The aim of the study was to determine the rate of change in organic compounds and nutrients in municipal wastewater with the participation of dairy products during the processing phases of SBR-type reactor in a technical scale. The study was conducted in WWTP in Sokolka. Rate of changes in the concentrations of organic compounds, nitrogen and phosphorus in wastewater during the processing phases of SBR reactor was determined. Presence of dairy sewage (13% volume participation affected the decrease in the rate of changes in organic compounds concentrations defined as BOD5 during all processing phases of SBR reactor. Significant influence of dairy sewage on rates of change in nitrogen and phosphorus compounds concentrations during filling, aeration, stirring, sedimentation and decantation phases, was found.

  13. Optimization of separation and online sample concentration of N,N-dimethyltryptamine and related compounds using MEKC.

    Science.gov (United States)

    Wang, Man-Juing; Tsai, Chih-Hsin; Hsu, Wei-Ya; Liu, Ju-Tsung; Lin, Cheng-Huang

    2009-02-01

    The optimal separation conditions and online sample concentration for N,N-dimethyltryptamine (DMT) and related compounds, including alpha-methyltryptamine (AMT), 5-methoxy-AMT (5-MeO-AMT), N,N-diethyltryptamine (DET), N,N-dipropyltryptamine (DPT), N,N-dibutyltryptamine (DBT), N,N-diisopropyltryptamine (DiPT), 5-methoxy-DMT (5-MeO-DMT), and 5-methoxy-N,N-DiPT (5-MeO-DiPT), using micellar EKC (MEKC) with UV-absorbance detection are described. The LODs (S/N = 3) for MEKC ranged from 1.0 1.8 microg/mL. Use of online sample concentration methods, including sweeping-MEKC and cation-selective exhaustive injection-sweep-MEKC (CSEI-sweep-MEKC) improved the LODs to 2.2 8.0 ng/mL and 1.3 2.7 ng/mL, respectively. In addition, the order of migration of the nine tryptamines was investigated. A urine sample, obtained by spiking urine collected from a human volunteer with DMT, was also successfully examined.

  14. Comparison of extracts and toxicities of organic compounds in drinking water concentrated by single and composite XAD resins.

    Science.gov (United States)

    Zhou, Xue; Xiang, Lunhui; Wu, Fenghong; Peng, Xiaoling; Xie, Hong; Wang, Jiachun; Yang, Kedi; Lu, Wenqing; Wu, Zhigang

    2013-12-01

    We compared extracts and toxicities of organic compounds (OCs) in drinking water concentrated by composite XAD-2/8 resin (mixed with an equal volume of XAD-2 and XAD-8 resins) with those extracted by single XAD-2 (non-polar) and XAD-8 (polar) resins. Drinking water was processed from raw water of the Han River and the Yangtze River in Wuhan section, China. The extraction efficiency of all resins was controlled at 30%. The types of extracted OCs were detected by gas chromatography-mass spectrometry, and the cytotoxicity and genotoxicity were assessed by MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) and comet assays, respectively, in human hepatoma HepG2 cells. Our results showed that XAD-2/8 extracted a larger variety of OCs, compared with XAD-8 and XAD-2. The cytotoxicity and genotoxicity of extracted OCs were in the order of XAD-8> XAD-2/8> XAD-2 at almost all tested concentrations after 24 h treatment (P < 0.05). Our findings suggest that single XAD resin selectively extracts either polar or non-polar OCs, which would lead to over- or under-estimation of the toxicity of drinking water. Nevertheless, composite resin extracts both polar and non-polar OCs, and could be utilized as a useful extraction technique to evaluate the level and toxicity of OCs in drinking water.

  15. Serum concentrations of TCDD and other dioxin-like compounds in US Air Force veterans of Operation Ranch Hand.

    Science.gov (United States)

    Pavuk, Marian; Patterson, Donald G; Turner, Wayman E

    2014-05-01

    We measured serum concentrations of seven dibenzo-p-dioxin congeners (PCDDs), ten dibenzofurans (PCDFs), four non-ortho polychlorinated biphenyls (noPCBs) and six mono-ortho polychlorinated biphenyls (moPCBs) in 1950 veterans of the Vietnam War. The veterans were participants in the Air Force Health Study (AFHS) who attended the final medical examination in 2002. Blood samples were collected from 777 Ranch Hands involved in the aerial spraying of herbicides in Vietnam and a comparison group of 1173 veterans ("Comparisons") who served in Southeast Asia during the same time period. Results for moPCBs were based on a random subsample of 800 veterans. The median 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) concentrations in 2002 were 5.0 pg g(-1) lipid in Ranch Hands and 2.2 pg g(-1) lipid in Comparisons. No substantial differences were found in measured concentrations of other PCDDs, PCDFs, and noPCBs. Similarly, no substantial differences were found for moPCBs in the subsample. The median total dioxin toxic equivalent (TEQ) in Ranch Hands was 18.7 pg g(-1) lipid for PCDDs, 3.4 pg g(-1) lipid for PCDFs, and 3.2 pg g(-1) lipid for noPCBs. Median TEQs in Comparisons were 14.4 pg g(-1) lipid for PCDDs, 3.5 pg g(-1) lipid for PCDFs, and 3.3 pg g(-1) lipid for noPCBs. These TEQs, with the exception of PCDD TEQ in Ranch Hands (primarily due to elevated TCDD), were similar to or lower than those reported for similar age and gender groups in the 2001-2002 National Health and Nutrition Examination Survey (NHANES). These findings support the assumption that the Ranch Hand veterans were not more highly exposed to dioxin-like compounds other than TCDD than were Comparison veterans or the general US population.

  16. Volatile Organic Compound (VOC Removal by Vapor Permeation at Low VOC Concentrations: Laboratory Scale Results and Modeling for Scale Up

    Directory of Open Access Journals (Sweden)

    Philippe Moulin

    2011-03-01

    Full Text Available Petroleum transformation industries have applied membrane processes for solvent and hydrocarbon recovery as an economic alternative to reduce their emissions and reuse evaporated components. Separation of the volatile organic compounds (VOCs (toluene-propylene-butadiene from air was performed using a poly dimethyl siloxane (PDMS/α-alumina membrane. The experimental set-up followed the constant pressure/variable flow set-up and was operated at ~21 °C. The membrane is held in a stainless steel module and has a separation area of 55 × 10−4 m². Feed stream was set to atmospheric pressure and permeate side to vacuum between 3 and 5 mbar. To determine the performance of the module, the removed fraction of VOC was analyzed by Gas Chromatography/Flame Ionization Detector (GC/FID. The separation of the binary, ternary and quaternary hydrocarbon mixtures from air was performed at different flow rates and more especially at low concentrations. The permeate flux, permeance, enrichment factor, separation efficiency and the recovery extent of the membrane were determined as a function of these operating conditions. The permeability coefficients and the permeate flux through the composite PDMS-alumina membrane follow the order given by the Hildebrand parameter: toluene > 1,3-butadiene > propylene. The simulated data for the binary VOC/air mixtures showed fairly good agreement with the experimental results in the case of 1,3-butadiene and propylene. The discrepancies observed for toluene permeation could be minimized by taking into account the effects of the porous support and an influence of the concentration polarization. Finally, the installation of a 0.02 m2 membrane module would reduce 95% of the VOC content introduced at real concentration conditions used in the oil industry.

  17. Volatile Organic Compound (VOC) Removal by Vapor Permeation at Low VOC Concentrations: Laboratory Scale Results and Modeling for Scale Up.

    Science.gov (United States)

    Rebollar-Perez, Georgette; Carretier, Emilie; Lesage, Nicolas; Moulin, Philippe

    2011-03-03

    Petroleum transformation industries have applied membrane processes for solvent and hydrocarbon recovery as an economic alternative to reduce their emissions and reuse evaporated components. Separation of the volatile organic compounds (VOCs) (toluene-propylene-butadiene) from air was performed using a poly dimethyl siloxane (PDMS)/α-alumina membrane. The experimental set-up followed the constant pressure/variable flow set-up and was operated at ~21 °C. The membrane is held in a stainless steel module and has a separation area of 55 × 10-4 m². Feed stream was set to atmospheric pressure and permeate side to vacuum between 3 and 5 mbar. To determine the performance of the module, the removed fraction of VOC was analyzed by Gas Chromatography/Flame Ionization Detector (GC/FID). The separation of the binary, ternary and quaternary hydrocarbon mixtures from air was performed at different flow rates and more especially at low concentrations. The permeate flux, permeance, enrichment factor, separation efficiency and the recovery extent of the membrane were determined as a function of these operating conditions. The permeability coefficients and the permeate flux through the composite PDMS-alumina membrane follow the order given by the Hildebrand parameter: toluene > 1,3-butadiene > propylene. The simulated data for the binary VOC/air mixtures showed fairly good agreement with the experimental results in the case of 1,3-butadiene and propylene. The discrepancies observed for toluene permeation could be minimized by taking into account the effects of the porous support and an influence of the concentration polarization. Finally, the installation of a 0.02 m2 membrane module would reduce 95% of the VOC content introduced at real concentration conditions used in the oil industry.

  18. Comparison of atmospheric concentrations of sulphur and nitrogen compounds, chloride and base cations at Ahtari and Hyytiala, Finland

    Energy Technology Data Exchange (ETDEWEB)

    Ruoho-Airola, T. [Finnish Meteorological Institute, Helsinki (Finland)

    2012-11-01

    Seven-year (2003-2009) time series of atmospheric SO{sub 2}, SO{sub 4}{sup 2-}, NO{sub 3}-, NH{sub 4}{sup +} and Cl{sup -} concentrations as well as four-year time series of atmospheric Na{sup +}, K{sup +}, Ca{sup 2+} and Mg{sup 2+} concentrations from Ahtari and Hyytiala background stations in southern Finland, located within 85 km of each other were compared. At Ahtari the air sampler was located in a clearing within a young forest, while at Hyytiala it was within dense forest stands. Pearson's correlations between the time series were very strong (r{sub P} {>=} 0.9) for SO{sub 2}, SO{sub 4}{sup 2-}, NO{sub 3}{sup -}, NH{sub 4}{sup +}, Cl{sup -} and Ca{sup 2+}, strong (r{sub P} > 0.8) for Na{sup +} and Mg{sup 2+} and week (r{sub P} = 0.65) for K{sup +}. The concentrations recorded at Hyytiala were on average 0.8-1.0 times those at Ahtari, although for K{sup +} and Ca{sup 2+} the ratios were higher. The GLS-ARMA method used takes into account the seasonal behaviour and serial correlation in the air quality time series, which revealed similar seasonal and temporal behaviour for S and N compounds and Cl- at both stations. As a result of the dense seasonalization of the time series, the part of the data heavily influenced by local agricultural sources could be identified. This enables elimination of the minimal part of the data affected and the use of the remaining data for further studies on a more regional level. (orig.)

  19. Electronic Nose Functionality for Breath Gas Analysis during Parabolic Flight

    Science.gov (United States)

    Dolch, Michael E.; Hummel, Thomas; Fetter, Viktor; Helwig, Andreas; Lenic, Joachim; Moukhamedieva, Lana; Tsarkow, Dimitrij; Chouker, Alexander; Schelling, Gustav

    2017-02-01

    The presence of humans in space represents a constant threat for their health and safety. Environmental factors such as living in a closed confinement, as well as exposure to microgravity and radiation, are associated with significant changes in bone metabolism, muscular atrophy, and altered immune response, which has impacts on human performance and possibly results in severe illness. Thus, maintaining and monitoring of crew health status has the highest priority to ensure whole mission success. With manned deep space missions to moon or mars appearing at the horizon where short-term repatriation back to earth is impossible the availability of appropriate diagnostic platforms for crew health status is urgently needed. In response to this need, the present experiment evaluated the functionality and practicability of a metal oxide based sensor system (eNose) together with a newly developed breath gas collecting device under the condition of altering acceleration. Parabolic flights were performed with an Airbus A300 ZeroG at Bordeaux, France. Ambient air and exhaled breath of five healthy volunteers was analyzed during steady state flight and parabolic flight maneuvres. All volunteers completed the study, the breath gas collecting device valves worked appropriately, and breathing through the collecting device was easy and did not induce discomfort. During breath gas measurements, significant changes in metal oxide sensors, mainly sensitive to aromatic and sulphur containing compounds, were observed with alternating conditions of acceleration. Similarly, metal oxide sensors showed significant changes in all sensors during ambient air measurements. The eNose as well as the newly developed breath gas collecting device, showed appropriate functionality and practicability during alternating conditions of acceleration which is a prerequisite for the intended use of the eNose aboard the International Space Station (ISS) for breath gas analysis and crew health status

  20. Electronic Nose Functionality for Breath Gas Analysis during Parabolic Flight

    Science.gov (United States)

    Dolch, Michael E.; Hummel, Thomas; Fetter, Viktor; Helwig, Andreas; Lenic, Joachim; Moukhamedieva, Lana; Tsarkow, Dimitrij; Chouker, Alexander; Schelling, Gustav

    2017-06-01

    The presence of humans in space represents a constant threat for their health and safety. Environmental factors such as living in a closed confinement, as well as exposure to microgravity and radiation, are associated with significant changes in bone metabolism, muscular atrophy, and altered immune response, which has impacts on human performance and possibly results in severe illness. Thus, maintaining and monitoring of crew health status has the highest priority to ensure whole mission success. With manned deep space missions to moon or mars appearing at the horizon where short-term repatriation back to earth is impossible the availability of appropriate diagnostic platforms for crew health status is urgently needed. In response to this need, the present experiment evaluated the functionality and practicability of a metal oxide based sensor system (eNose) together with a newly developed breath gas collecting device under the condition of altering acceleration. Parabolic flights were performed with an Airbus A300 ZeroG at Bordeaux, France. Ambient air and exhaled breath of five healthy volunteers was analyzed during steady state flight and parabolic flight maneuvres. All volunteers completed the study, the breath gas collecting device valves worked appropriately, and breathing through the collecting device was easy and did not induce discomfort. During breath gas measurements, significant changes in metal oxide sensors, mainly sensitive to aromatic and sulphur containing compounds, were observed with alternating conditions of acceleration. Similarly, metal oxide sensors showed significant changes in all sensors during ambient air measurements. The eNose as well as the newly developed breath gas collecting device, showed appropriate functionality and practicability during alternating conditions of acceleration which is a prerequisite for the intended use of the eNose aboard the International Space Station (ISS) for breath gas analysis and crew health status

  1. The JPL parabolic dish project. [solar collectors technology development

    Science.gov (United States)

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

    1980-01-01

    The parabolic dish solar collector is a highly versatile concentrating collector system that can produce heat for many thermal processes and electricity by coupling the collector to a suitable heat engine. This paper discusses a project for the development of these collector systems and summarizes contracts with industry for developing the dish subsystems which include concentrator, receiver, and heat engine. An early market for dishes is the dispersed small community market which depends heavily on oil to operate diesel or steam turbine plants in order to generate electricity. The present contracts with industry for conducting engineering experiments using the developed dish hardware to demonstrate the technology in these early opportunity markets is also discussed.

  2. Thermal and optical efficiency investigation of a parabolic trough collector

    Directory of Open Access Journals (Sweden)

    C. Tzivanidis

    2015-09-01

    Full Text Available Solar energy utilization is a promising Renewable Energy source for covering a variety of energy needs of our society. This study presents the most well-known solar concentrating system, the parabolic trough collector, which is operating efficiently in high temperatures. The simulation tool of this analysis is the commercial software Solidworks which simulates complicated problems with an easy way using the finite elements method. A small parabolic trough collector model is designed and simulated for different operating conditions. The goal of this study is to predict the efficiency of this model and to analyze the heat transfer phenomena that take place. The efficiency curve is compared to a one dimensional numerical model in order to make a simple validation. Moreover, the temperature distribution in the absorber and inside the tube is presented while the heat flux distribution in the outer surface of the absorber is given. The heat convection coefficient inside the tube is calculated and compared with the theoretical one according to the literature. Also the angle efficiency modifier is calculated in order to predict the thermal and optical efficiency for different operating conditions. The final results show that the PTC model performs efficiently and all the calculations are validated.

  3. Parabolic dish collectors - A solar option

    Science.gov (United States)

    Truscello, V. C.

    1981-01-01

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

  4. Who dares to join a parabolic flight?

    Science.gov (United States)

    Montag, Christian; Zander, Tina; Schneider, Stefan

    2016-12-01

    Parabolic flights represent an important tool in space research to investigate zero gravity on airplanes. Research on these flights often target psychological and biological processes in humans to investigate if and how we can adapt to this unique environment. This research is costly, hard to conduct and clearly heavily relies on humans participating in experiments in this (unnatural) situation. The present study investigated N =66 participants and N =66 matched control persons to study if participants in such experimental flights differ in terms of their personality traits from non-parabonauts. The main finding of this study demonstrates that parabonauts score significantly lower on harm avoidance, a trait closely linked to being anxious. As anxious humans differ from non-anxious humans in their biology, the present observations need to be taken into account when aiming at the generalizability of psychobiological research findings conducted in zero gravity on parabolic flights.

  5. Antiperiodic Problems for Nonautonomous Parabolic Evolution Equations

    Directory of Open Access Journals (Sweden)

    R. N. Wang

    2014-01-01

    Full Text Available This work focuses on the antiperiodic problem of nonautonomous semilinear parabolic evolution equation in the form u′(t=A(tu(t+f(t,u(t, t∈R, u(t+T=-u(t, t∈R, where (Att∈R (possibly unbounded, depending on time, is a family of closed and densely defined linear operators on a Banach space X. Upon making some suitable assumptions such as the Acquistapace and Terreni conditions and exponential dichotomy on (Att∈R, we obtain the existence results of antiperiodic mild solutions to such problem. The antiperiodic problem of nonautonomous semilinear parabolic evolution equation of neutral type is also considered. As sample of application, these results are applied to, at the end of the paper, an antiperiodic problem for partial differential equation, whose operators in the linear part generate an evolution family of exponential stability.

  6. 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...

  7. Emissions of volatile organic compounds (VOCs) from concentrated animal feeding operations (CAFOs): chemical compositions and separation of sources

    Science.gov (United States)

    Yuan, Bin; Coggon, Matthew M.; Koss, Abigail R.; Warneke, Carsten; Eilerman, Scott; Peischl, Jeff; Aikin, Kenneth C.; Ryerson, Thomas B.; de Gouw, Joost A.

    2017-04-01

    Concentrated animal feeding operations (CAFOs) emit a large number of volatile organic compounds (VOCs) to the atmosphere. In this study, we conducted mobile laboratory measurements of VOCs, methane (CH4) and ammonia (NH3) downwind of dairy cattle, beef cattle, sheep and chicken CAFO facilities in northeastern Colorado using a hydronium ion time-of-flight chemical-ionization mass spectrometer (H3O+ ToF-CIMS), which can detect numerous VOCs. Regional measurements of CAFO emissions in northeastern Colorado were also performed using the NOAA WP-3D aircraft during the Shale Oil and Natural Gas Nexus (SONGNEX) campaign. Alcohols and carboxylic acids dominate VOC concentrations and the reactivity of the VOCs with hydroxyl (OH) radicals. Sulfur-containing and phenolic species provide the largest contributions to the odor activity values and the nitrate radical (NO3) reactivity of VOC emissions, respectively. VOC compositions determined from mobile laboratory and aircraft measurements generally agree well with each other. The high time-resolution mobile measurements allow for the separation of the sources of VOCs from different parts of the operations occurring within the facilities. We show that the emissions of ethanol are primarily associated with feed storage and handling. Based on mobile laboratory measurements, we apply a multivariate regression analysis using NH3 and ethanol as tracers to determine the relative importance of animal-related emissions (animal exhalation and waste) and feed-related emissions (feed storage and handling) for different VOC species. Feed storage and handling contribute significantly to emissions of alcohols, carbonyls, carboxylic acids and sulfur-containing species. Emissions of phenolic species and nitrogen-containing species are predominantly associated with animals and their waste.

  8. A short proof of increased parabolic regularity

    Directory of Open Access Journals (Sweden)

    Stephen Pankavich

    2015-08-01

    Full Text Available We present a short proof of the increased regularity obtained by solutions to uniformly parabolic partial differential equations. Though this setting is fairly introductory, our new method of proof, which uses a priori estimates and an inductive method, can be extended to prove analogous results for problems with time-dependent coefficients, advection-diffusion or reaction diffusion equations, and nonlinear PDEs even when other tools, such as semigroup methods or the use of explicit fundamental solutions, are unavailable.

  9. Parabolic cylinder functions of large order

    Science.gov (United States)

    Jones, D. S.

    2006-06-01

    The asymptotic behaviour of parabolic cylinder functions of large real order is considered. Various expansions in terms of elementary functions are derived. They hold uniformly for the variable in appropriate parts of the complex plane. Some of the expansions are doubly asymptotic with respect to the order and the complex variable which is an advantage for computational purposes. Error bounds are determined for the truncated versions of the asymptotic series.

  10. INVERSE COEFFICIENT PROBLEMS FOR PARABOLIC HEMIVARIATIONAL INEQUALITIES

    Institute of Scientific and Technical Information of China (English)

    Liu Zhenhai; I.Szántó

    2011-01-01

    This paper is devoted to the class of inverse problems for a nonlinear parabolic hemivariational inequality.The unknown coefficient of the operator depends on the gradient of the solution and belongs to a set of admissible coefficients.It is proved that the convergence of solutions for the corresponding direct problems continuously depends on the coefficient convergence.Based on this result the existence of a quasisolution of the inverse problem is obtained.

  11. Study on a Cross Diffusion Parabolic System

    Institute of Scientific and Technical Information of China (English)

    Li Chen; Ling Hsiao; Gerald Warnecke

    2007-01-01

    This paper considers a kind of strongly coupled cross diffusion parabolic system, which can be used as the multi-dimensional Lyumkis energy transport model in semiconductor science. The global existence and large time behavior are obtained for smooth solution to the initial boundary value problem. When the initial data are a small perturbation of an isothermal stationary solution, the smooth solution of the problem under the insulating boundary condition, converges to that stationary solution exponentially fast as time goes to infinity.

  12. Controllability of nonlinear degenerate parabolic cascade systems

    Directory of Open Access Journals (Sweden)

    Mamadou Birba

    2016-08-01

    Full Text Available This article studies of null controllability property of nonlinear coupled one dimensional degenerate parabolic equations. These equations form a cascade system, that is, the solution of the first equation acts as a control in the second equation and the control function acts only directly on the first equation. We prove positive null controllability results when the control and a coupling set have nonempty intersection.

  13. Parabolic resection for mitral valve repair.

    Science.gov (United States)

    Drake, Daniel H; Drake, Charles G; Recchia, Dino

    2010-02-01

    Parabolic resection, named for the shape of the cut edges of the excised tissue, expands on a common 'trick' used by experienced mitral surgeons to preserve tissue and increase the probability of successful repair. Our objective was to describe and clinically analyze this simple modification of conventional resection. Thirty-six patients with mitral regurgitation underwent valve repair using parabolic resection in combination with other techniques. Institution specific mitral data, Society of Thoracic Surgeons data and preoperative, post-cardiopulmonary bypass (PCPB) and postoperative echocardiography data were collected and analyzed. Preoperative echocardiography demonstrated mitral regurgitation ranging from moderate to severe. PCPB transesophageal echocardiography demonstrated no regurgitation or mild regurgitation in all patients. Thirty-day surgical mortality was 2.8%. Serial echocardiograms demonstrated excellent repair stability. One patient (2.9%) with rheumatic disease progressed to moderate regurgitation 33 months following surgery. Echocardiography on all others demonstrated no or mild regurgitation at a mean follow-up of 22.8+/-12.8 months. No patient required mitral reintervention. Longitudinal analysis demonstrated 80% freedom from cardiac death, reintervention and greater than moderate regurgitation at four years following repair. Parabolic resection is a simple technique that can be very useful during complex mitral reconstruction. Early and intermediate echocardiographic studies demonstrate excellent results.

  14. Simulation of parabolic reflectors for ultraviolet phototherapy

    Science.gov (United States)

    Grimes, David Robert

    2016-08-01

    Ultraviolet (UVR) phototherapy is widely used to treat an array of skin conditions, including psoriasis, eczema and vitiligo. For such interventions, a quantified dose is vital if the treatment is to be both biologically effective and to avoid the detrimental effects of over-dosing. As dose is absorbed at surface level, the orientation of patient site with respect to the UVR lamps modulates effective dose. Previous investigations have modelled this behaviour, and examined the impact of shaped anodized aluminium reflectors typically placed around lamps in phototherapy cabins. These mirrors are effective but tend to yield complex patterns of reflection around the cabin which can result in substantial dose inhomogeneity. There has been some speculation over whether using the reflective property of parabolic mirrors might improve dose delivery or homogeneity through the treatment cabin. In this work, the effects of parabolic mirrors are simulated and compared with standard shaped mirrors. Simulation results strongly suggest that parabolic reflectors reduce total irradiance relative to standard shaped reflectors, and have a negligible impact on dose homogeneity.

  15. Simulation of parabolic reflectors for ultraviolet phototherapy.

    Science.gov (United States)

    Robert Grimes, David

    2016-08-21

    Ultraviolet (UVR) phototherapy is widely used to treat an array of skin conditions, including psoriasis, eczema and vitiligo. For such interventions, a quantified dose is vital if the treatment is to be both biologically effective and to avoid the detrimental effects of over-dosing. As dose is absorbed at surface level, the orientation of patient site with respect to the UVR lamps modulates effective dose. Previous investigations have modelled this behaviour, and examined the impact of shaped anodized aluminium reflectors typically placed around lamps in phototherapy cabins. These mirrors are effective but tend to yield complex patterns of reflection around the cabin which can result in substantial dose inhomogeneity. There has been some speculation over whether using the reflective property of parabolic mirrors might improve dose delivery or homogeneity through the treatment cabin. In this work, the effects of parabolic mirrors are simulated and compared with standard shaped mirrors. Simulation results strongly suggest that parabolic reflectors reduce total irradiance relative to standard shaped reflectors, and have a negligible impact on dose homogeneity.

  16. Seasonal variation of nitrogen oxides, ozone and biogenic volatile organic compound concentrations and fluxes at Norway spruce forest

    Science.gov (United States)

    Juran, Stanislav; Vecerova, Kristyna; Holisova, Petra; Zapletal, Milos; Pallozzi, Emanuele; Guidolotti, Gabriele; Calfapietra, Carlo; Vecera, Zbynek; Cudlin, Pavel; Urban, Otmar

    2015-04-01

    Dynamics of nitrogen oxides (NOx) and ozone concentration and their depositions were investigated on the Norway spruce forest at Bily Kriz experimental station at the Silesian Beskydy Mountains (north-eastern part of the Czech Republic). Both NOx and ozone concentration and fluxes were modelled for the whole season and covering thus different climate conditions. Data were recorded for three consecutive years and therefore deeper analyses were performed. During the summer 2014 BVOC field campaign was carried out using proton-transfer-reaction-time-of-flight-mass-spectrometry (PTR-TOF, Ionicon Analytik GmbH, Innsbruck, Austria) and volatile organic compound of biogenic origin (BVOC) were measured at the different levels of tree canopies. By the same time BVOC were trapped into the Tenax tubes (Markes International Ltd., UK) and put afterwards for thermal desorption (Markes Unity System 2, Markes International Ltd., UK) to GS-MS analysis (TSQ Quntum XLS triple Quadrupole, Thermo Scientific, USA). Thus data of different levels of canopies together with different spectra of monoterpenes were obtained. Interesting comparison of both methods will be shown. It was the first BVOC field campaign using PTR technique at any of the forest in the Czech Republic. Highest fluxes and concentrations were recorded around the noon hours, represented particularly by monoterpenes, especially α-pinen and limonene. Other BVOCs than monoterpenes were negligible. Variation of fluxes between different canopies levels was observed, highlighting difference in shaded and sun exposed leaves. Sun leaves emitted up to 2.4 nmol m-2 s-1 of monoterpenes, while shaded leaves emitted only up to 0.6 nmol m-2 s-1 when measured under standard conditions (irradiance 1000 µmol m-2 s-1; temperature 30°C). We discuss here the importance of the most common Norway spruce tree forests in the Czech Republic in bi-directional exchanges of important secondary pollutant such as ozone and nitrogen oxides, their

  17. Femtosecond parabolic pulse shaping in normally dispersive optical fibers.

    Science.gov (United States)

    Sukhoivanov, Igor A; Iakushev, Sergii O; Shulika, Oleksiy V; Díez, Antonio; Andrés, Miguel

    2013-07-29

    Formation of parabolic pulses at femtosecond time scale by means of passive nonlinear reshaping in normally dispersive optical fibers is analyzed. Two approaches are examined and compared: the parabolic waveform formation in transient propagation regime and parabolic waveform formation in the steady-state propagation regime. It is found that both approaches could produce parabolic pulses as short as few hundred femtoseconds applying commercially available fibers, specially designed all-normal dispersion photonic crystal fiber and modern femtosecond lasers for pumping. The ranges of parameters providing parabolic pulse formation at the femtosecond time scale are found depending on the initial pulse duration, chirp and energy. Applicability of different fibers for femtosecond pulse shaping is analyzed. Recommendation for shortest parabolic pulse formation is made based on the analysis presented.

  18. Describing Quadratic Cremer Point Polynomials by Parabolic Perturbations

    DEFF Research Database (Denmark)

    Sørensen, Dan Erik Krarup

    1996-01-01

    .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...... external ray accumulating the Cremer point, but having in itsimpression both the Cremer point and its other preimage. We think of the Julia setas containing a "topologists single comb".By tuning, similar results hold on the boundary of any hyperbolic component of theMandelbrot set....

  19. The parabolic Anderson model random walk in random potential

    CERN Document Server

    König, Wolfgang

    2016-01-01

    This is a comprehensive survey on the research on the parabolic Anderson model – the heat equation with random potential or the random walk in random potential – of the years 1990 – 2015. The investigation of this model requires a combination of tools from probability (large deviations, extreme-value theory, e.g.) and analysis (spectral theory for the Laplace operator with potential, variational analysis, e.g.). We explain the background, the applications, the questions and the connections with other models and formulate the most relevant results on the long-time behavior of the solution, like quenched and annealed asymptotics for the total mass, intermittency, confinement and concentration properties and mass flow. Furthermore, we explain the most successful proof methods and give a list of open research problems. Proofs are not detailed, but concisely outlined and commented; the formulations of some theorems are slightly simplified for better comprehension.

  20. Fifth parabolic dish solar thermal power program annual review: proceedings

    Energy Technology Data Exchange (ETDEWEB)

    None

    1984-03-01

    The primary objective of the Review was to present the results of activities within the Parabolic Dish Technology and Module/Systems Development element of the Department of Energy's Solar Thermal Energy Systems Program. The Review consisted of nine technical sessions covering overall Project and Program aspects, Stirling and Brayton module development, concentrator and engine/receiver development, and associated hardware and test results to date; distributed systems operating experience; international dish development activities; and non-DOE-sponsored domestic dish activities. A panel discussion concerning business views of solar electric generation was held. These Proceedings contain the texts of presentations made at the Review, as submitted by their authors at the beginning of the Review; therefore, they may vary slightly from the actual presentations in the technical sessions.

  1. Fabrication of the solar furnace`s segmental main parabolic mirror

    Energy Technology Data Exchange (ETDEWEB)

    Shishido, K. [Tohoku Gakuin Univ., Tagajo, Miyagi (Japan); Kitahara, H. [Tohoku Electric Power Co. Ltd., Sendai (Japan); Fujisaki, H.; Shoji, T. [Tohoku Gakuin Univ., Tagajo, Miyagi (Japan); Shibata, Y. [Tohoku Univ., Sendai (Japan); Sugiura, M. [Koyodai High School, Miyagi, Sendai (Japan); Nagai, Y. [Press Kogyo Company Ltd., Fujisawa (Japan); Kobayashi, H. [Tokyo Special Glass Company Ltd., Fujioka (Japan)

    1994-12-31

    The development of a new energy system based on the concentration of the rays of the sun was trialed and four solar furnaces produced. However, the fabrication of the segmented main parabolic mirror required high precision and was found to be very difficult. The main parabolic mirror of the furnaces were of the segmental type. The mirrors in the large furnace of the first trial in 1962 were made by a cutting machine with a cam mechanism and then finished by grinding and polishing. The segmental main parabolic mirrors of the small and medium-size furnaces (2nd and 3rd trials) were made using master molds (for softening the glass segments) that were fabricated using a cutting machine having a link mechanism. The fourth furnace used mirrors composed of super reflecting A1 plate cemented on a stamped plastic base. The cutting techniques and the grinding and polishing of the glass to fabricate the fan-shaped segmental parabolic mirrors were successful, but the softening results were not ideal. Better results were obtained on softening narrow fan-shaped glass plates and the ideal tools for cutting the master molds of soft brick are considered to be the glass gauge or cylinder tube. 10 figs., 4 refs.

  2. Blood concentrations and risk assessment of persistent organochlorine compounds in newborn boys in Turkey. A pilot study.

    Science.gov (United States)

    Ulutaş, Onur Kenan; Çok, İsmet; Darendeliler, Feyza; Aydin, Banu; Çoban, Asuman; Henkelmann, Bernhard; Schramm, Karl-Werner

    2015-12-01

    Even early life in utero cannot provide a safe place for newborns. The first acquaintance with chemicals takes place in utero and/or with mother's milk after delivery. Besides legislations and bans to persistent organic pollutants (POPs), these chemicals are still affecting the general population especially the children as they are one of the populations most susceptible to chemicals, and also the health problems may arise in the future. Our objective is to collect the first data in newborns in Turkey to determine baseline levels of POPs in the general population and estimate the potential cancer risk related to exposure. Twenty-nine organochlorine pesticides (OCPs) and 18 polychlorinated biphenyl (PCB) congeners in blood samples of newborn boys (0-1 month old) who were born in İstanbul, Turkey, in 2010-2012 were evaluated with high-resolution gas chromatography-high-resolution mass spectrometry (HRGC/HRMS). Results for analyzed chlorinated compounds are as follows: hexachlorocyclohexane (ΣHCH) 1828 ± 3650 pg/g lipid, dichlorodiphenyltrichloroethane (ΣDDT) 10,000 ± 15,398 pg/g lipid, and ΣPCB 1068 ± 1823 pg/g lipid. 4,4'-DDT, 4,4'-dichlorodiphenyldichloroethylene (4,4'-DDE), hexachlorobenzene, and PCB 138 and 153 are the major contaminants. New POPs as lindane 61 ± 268 pg/g lipid, pentachlorobenzene 13 ± 74 pg/g lipid, and endosulfan 29 ± 106 pg/g lipid are also detected in blood. Estimated total risk for lifetime PCB exposure is less than 1 × 10(-5), an acceptable risk. Blood concentration levels will be important base data in the assessment of health concerns of newborns as well as for studies about how endocrine disruptors affect humans.

  3. Estimation of Secondary Compounds Concentrations Contributed by Biogenic VOC With Chemical Transport Model in the Central Area of Japan

    Science.gov (United States)

    Yamamoto, K.; Kanemaru, A.; Okumura, M.; Tohno, S.

    2008-12-01

    meteorological fields was used for estimating secondary produced compounds concentration in the Kansai region. While the emission amount data of BVOC is also included in the EAGrid-Japan database, constructed by A. Kannari et al., another simulation with this existing BVOC emission inventory was conducted. As for other emission inventories of precursors, EAGrid-Japan was also used in both simulations. According to the result of estimation of BVOC emission, the total amount of BVOC is almost same as that of EAGrid-Japan, however, the ratio of isoprene to total BVOC emission is quite low in our estimation, due to the used vegetation map in this study, and the configuration of basic emission parameter in Autumn and Winter which is set to zero. According to the result of atmospheric chemical transport simulation with this developed BVOC inventory, oxidant concentrations are lower than observed values. This result suggests that the amount of isoprene emission strongly affected on the concentrations of oxidants, therefore, more accurate vegetation map data as a basis of BVOC emissions should be developed.

  4. System for determining the concentration and visualization of the spatial distribution of photosensitizers based on tetrapyrrole compounds in the tissues of the human ocular fundus

    Science.gov (United States)

    Model, Sergey S.; Savelieva, Tatiana A.; Linkov, Kirill G.

    2013-02-01

    We developed a system for the analysis of the spatial distribution of photosensitizers (PS) based on tetrapyrrole compounds in the tissues of the retina. Tetrapyrrole compounds were chosen because the most of them are characterized by strong absorption in the tissue transparency window. Calibration curves for determining the concentration of PS by different methods were constructed. Registration system of PS's fluorescence consists of two optical channels. First channel based on single point spectroscopic technique is used to determine exact concentration of PS at a certain point of the field. Second channel based on imaging sensor is used for concentration mapping in whole field of view. The joint use of these two methods allows determining the concentration of PS in different points of the field quickly and accurately, which provides the exact determination of tissues in pathologic condition and informed choice of irradiation dose for photodynamic therapy.

  5. Bifurcation and stability for a nonlinear parabolic partial differential equation

    Science.gov (United States)

    Chafee, N.

    1973-01-01

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

  6. Measurement of Liquid Viscosities in Tapered or Parabolic Capillaries.

    Science.gov (United States)

    Ershov; Zorin; Starov

    1999-08-01

    The possibility of using tapered or parabolic capillaries for measurement of liquid viscosities is investigated both experimentally and theoretically. It is demonstrated that even small deviations in capillary radius from a constant value may substantially affect measurement results. Equations are derived which allow correct analysis of the measurement results in tapered or parabolic capillaries. The following cases are analyzed: a water imbibition into a tapered or parabolic capillary and displacement of one liquid by another immiscible liquid in tapered or parabolic capillaries. Two possibilities are considered: (a) the narrow end of the capillary as capillary inlet and (b) the wide end of the capillary as capillary inlet. Copyright 1999 Academic Press.

  7. Electrons per atom ratio determination and Hume-Rothery electron concentration rule for P-based polar compounds studied by FLAPW-fourier calculations.

    Science.gov (United States)

    Mizutani, Uichiro; Sato, Hirokazu; Inukai, Manabu; Nishino, Yoichi; Zijlstra, Eeuwe Sieds

    2015-02-02

    The extent to which reliable electrons per atom ratio, e/a, are determined and the validity of the Hume-Rothery stabilization mechanism are ensured upon increasing ionicity are studied by applying first-principles full potential linearized augmented plane wave (FLAPW)-Fourier band calculations to as many as 59 binary compounds formed by adding elements from periods 2-6 to phosphorus in group 15 of the Periodic Table. Van Arkel-Ketelaar triangle maps were constructed both by using the Allen electronegativity data and by using an energy difference between the center-of-gravity energies of FLAPW-derived s and p partial densities of states (DOSs) for the equiatomic compounds studied. The determination of e/a and the test of the interference condition, both of which play a key role in the Hume-Rothery stabilization mechanism, were reliably made for all intermetallic compounds, as long as the ionicity is less than 50%. In the A-P (A = Li, Na, K, Rb, and Cs) compounds with ionicity exceeding 50%, however, e/a determination becomes unstable, as reflected in its P concentration dependence. New Hume-Rothery electron concentration rules were theoretically found in two families of polar compounds: skutterudite compounds TMP(3), TMAs(3), and TMSb(3) (TM = Co, Ni, Rh, and Ir; cI32) with e/a = 4.34 and TM(3)P (TM = Cr, Mn, Fe, and Ni; tI32) with e/a = 2.20.

  8. Silicon concentrator cells in a two-stage photovoltaic system with a concentration factor of 300x

    Energy Technology Data Exchange (ETDEWEB)

    Mohr, A.

    2005-06-15

    In this work a rear contacted silicon concentrator cell was developed for an application in a two stage concentrator photovoltaic system. This system was developed at Fraunhofer ISE some years ago. The innovation of this one-axis tracked system is that it enables a high geometrical concentration of 300x in combination with a high optical efficiency (around 78%) and a large acceptance angle of {+-}23.5 all year through. For this, the system uses a parabolic mirror (40.4x) and a three dimensional second stage consisting of compound parabolic concentrators (CPCs, 7.7x). For the concentrator concept and particularly for an easy cell integration, the rear line contacted concentrator (RLCC) cells with a maximum efficiency of 25% were developed and a hybrid mounting concept for the RLCC cells is presented. The optical performance of different CPC materials was tested and analysed in this work. Finally, small modules consisting of six series interconnected RLCC cells and six CPCs were integrated into the concentrator system and tested outdoor. A system efficiency of 16.2% was reached at around 800 W/m2 direct irradiance under realistic outdoor conditions. (orig.)

  9. Optimal Wentzell Boundary Control of Parabolic Equations

    Energy Technology Data Exchange (ETDEWEB)

    Luo, Yousong, E-mail: yousong.luo@rmit.edu.au [RMIT University, School of Mathematical and Geospatial Sciences (Australia)

    2017-04-15

    This paper deals with a class of optimal control problems governed by an initial-boundary value problem of a parabolic equation. The case of semi-linear boundary control is studied where the control is applied to the system via the Wentzell boundary condition. The differentiability of the state variable with respect to the control is established and hence a necessary condition is derived for the optimal solution in the case of both unconstrained and constrained problems. The condition is also sufficient for the unconstrained convex problems. A second order condition is also derived.

  10. Linear Parabolic Maps on the Torus

    CERN Document Server

    Zyczkowski, K; Zyczkowski, Karol; Nishikawa, Takashi

    1999-01-01

    We investigate linear parabolic maps on the torus. In a generic case these maps are non-invertible and discontinuous. Although the metric entropy of these systems is equal to zero, their dynamics is non-trivial due to folding of the image of the unit square into the torus. We study the structure of the maximal invariant set, and in a generic case we prove the sensitive dependence on the initial conditions. We study the decay of correlations and the diffusion in the corresponding system on the plane. We also demonstrate how the rationality of the real numbers defining the map influences the dynamical properties of the system.

  11. Surface roughness estimation of a parabolic reflector

    CERN Document Server

    Casco, Nicolás A

    2010-01-01

    Random surface deviations in a reflector antenna reduce the aperture efficiency. This communication presents a method for estimating the mean surface deviation of a parabolic reflector from a set of measured points. The proposed method takes into account systematic measurement errors, such as the offset between the origin of reference frame and the vertex of the surface, and the misalignment between the surface rotation axis and the measurement axis. The results will be applied to perform corrections to the surface of one of the 30 m diameter radiotelescopes at the Instituto Argentino de Radioastronom\\'ia (IAR).

  12. Parabolic dunes in north-eastern Brazil

    CERN Document Server

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

    2007-01-01

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

  13. PERFORMANCE SIMULATION OF PARABOLIC TROUGH SOLAR COLLECTOR USING TWO FLUIDS (THERMIC OIL AND MOLTEN SALT

    Directory of Open Access Journals (Sweden)

    T. E. Boukelia

    2016-05-01

    Full Text Available The Parabolic trough solar collector is considered as one of the most proven, mature and commercial concentrating solar systems implemented in arid and semi-arid regions for energy production. It focuses sunlight onto a solar receiver by using mirrors and is finally converted to a useful thermal energy by means of a heat transfer fluid. The aims of this study are (i to develop a new methodology for simulation and performance evaluation of parabolic trough solar collector, in addition (i to compare the efficiencies of this system using two different fluids; thermic oil and molten solar salt. The validation of obtained results using this methodology shows a good agreement with those obtained by the experimental tests. Furthermore, this study favors the using of thermic oil as heat transfer fluid in the receiver instead of molten salt due to the high efficiency of the concentrator based on the first fluid in comparison to the second one.

  14. Measurement of absolute concentrations of individual compounds in metabolite mixtures by gradient-selective time-zero 1H-13C HSQC with two concentration references and fast maximum likelihood reconstruction analysis.

    Science.gov (United States)

    Hu, Kaifeng; Ellinger, James J; Chylla, Roger A; Markley, John L

    2011-12-15

    Time-zero 2D (13)C HSQC (HSQC(0)) spectroscopy offers advantages over traditional 2D NMR for quantitative analysis of solutions containing a mixture of compounds because the signal intensities are directly proportional to the concentrations of the constituents. The HSQC(0) spectrum is derived from a series of spectra collected with increasing repetition times within the basic HSQC block by extrapolating the repetition time to zero. Here we present an alternative approach to data collection, gradient-selective time-zero (1)H-(13)C HSQC(0) in combination with fast maximum likelihood reconstruction (FMLR) data analysis and the use of two concentration references for absolute concentration determination. Gradient-selective data acquisition results in cleaner spectra, and NMR data can be acquired in both constant-time and non-constant-time mode. Semiautomatic data analysis is supported by the FMLR approach, which is used to deconvolute the spectra and extract peak volumes. The peak volumes obtained from this analysis are converted to absolute concentrations by reference to the peak volumes of two internal reference compounds of known concentration: DSS (4,4-dimethyl-4-silapentane-1-sulfonic acid) at the low concentration limit (which also serves as chemical shift reference) and MES (2-(N-morpholino)ethanesulfonic acid) at the high concentration limit. The linear relationship between peak volumes and concentration is better defined with two references than with one, and the measured absolute concentrations of individual compounds in the mixture are more accurate. We compare results from semiautomated gsHSQC(0) with those obtained by the original manual phase-cycled HSQC(0) approach. The new approach is suitable for automatic metabolite profiling by simultaneous quantification of multiple metabolites in a complex mixture.

  15. ADAPTATION OF AQUIFER MICROBIAL COMMUNITIES TO THE BIODEGRADATION OF XENOBIOTIC COMPOUNDS: INFLUENCE OF SUBSTRATE CONCENTRATION AND PREEXPOSURE

    Science.gov (United States)

    Studies were conducted to examine the adaptation response of aquifer microbial communities to xenobiotic compounds and the influence of chemical preexposure in the laboratory and in situ on adaptation. Adaptation and biodegradation were assessed as mineralization and cellular inc...

  16. The dependency of compound biological effectiveness factors on the type and the concentration of administered neutron capture agents in boron neutron capture therapy

    OpenAIRE

    Masunaga, Shin-Ichiro; Sakurai, Yoshinori; Tanaka, Hiroki; Tano, Keizo; Suzuki, Minoru; Kondo, Natsuko; Narabayashi, Masaru; Nakagawa, Yosuke; Watanabe, Tsubasa; Maruhashi, Akira; ONO, KOJI

    2014-01-01

    Purpose To examine the effect of the type and the concentration of neutron capture agents on the values of compound biological effectiveness (CBE) in boron neutron capture therapy. Methods and materials After the subcutaneous administration of a 10 B-carrier, boronophenylalanine- 10 B (BPA) or sodium mercaptododecaborate- 10 B (BSH), at 3 separate concentrations, the 10 B concentrations in tumors were measured by γ-ray spectrometry. SCC VII tumor-bearing C3H/He mice received 5-bromo-2′-deoxyu...

  17. Use of wood-based materials in beef bedded manure packs: 2. Effect on odorous volatile organic compounds, odor activity value, , and nutrient concentrations.

    Science.gov (United States)

    Spiehs, Mindy J; Brown-Brandl, Tami M; Berry, Elaine D; Wells, James E; Parker, David B; Miller, Daniel N; Jaderborg, Jeffrey P; DiCostanzo, Alfred

    2014-07-01

    The objectives of this study were to determine the effects of three types of wood-based bedding materials (kiln-dried pine wood chips, dry cedar chips, and green cedar chips) and corn stover on the concentration of odorous volatile organic compounds (VOCs) and total in bedded pack material. Four bedded packs of each bedding material were maintained for two 42-d periods ( = 32; eight replicates/bedding material). Straight- and branched-chained fatty acids, aromatic compounds, and sulfide compounds were measured from the headspace above each bedded pack. Green cedar bedding had the highest concentration of odorous VOCs, and pine chip bedding had the lowest ( dry cedar, corn stover, and pine chip bedding. As the bedded packs aged, the concentration of odorous VOCs increased, particularly in the bedded packs containing green cedar chips and dry cedar chips. Total concentrations increased from Days 0 to 21 and then began to decline and were similar among all bedding materials ( < 0.10). Results of this study indicate that producers using a long-term bedded pack management in their facility may benefit from using pine chips because they do not appear to increase odor over time. Cedar-based bedding materials may be better suited for a scrape-and-haul system, where the bedded pack is removed after 1 or 2 wk. Total concentrations did not differ between any of the four bedding materials over time.

  18. The contribution of vehicular emission to the atmospheric concentrations of carbon compounds in the Metropolitan Area of Sao Paulo

    Science.gov (United States)

    Andrade, M.; Fornaro, A.; Miranda, R.; Ynoue, R. Y.; Freitas, E. D.; LAPAt-Laboratorio de Analise dos Processos Atmosfericos

    2013-05-01

    It is recognized that megacities have regional and global effects on climate, and that aerosols and Green House Gases (GHG) constitute the principal tracer of those effects. Such is the case in the Metropolitan Area of Sao Paulo (MASP), one of the largest mega-cities in the world. MASP has a population of almost 20 million inhabitants. The main source of air pollution is the transport sector. In this region, there are approximately 6.5 million passenger cars and commercial vehicles: 85% light duty, 3% heavy-duty diesel vehicles (diesel + 3% bio-diesel) and 12% motorcycles. Of the light duty vehicle, approximately 55% burn a mixture (v/v) of 78% gasoline with 22% ethanol (referred to as gasohol), 4% use hydrated ethanol (95% ethanol + 5% water), 38% flexible fuel vehicles capable of burning both gasohol as hydrated ethanol, and 2% use diesel. In average 50% of the fuel used in MASP is ethanol what brings the necessity of more studies to understand the formation of photochemical oxidants and secondary particles. According to the São Paulo State Environmental Protection Agency, 97% of carbon monoxide (CO), 85% of hydrocarbons (HC), 82% of nitrogen oxides (NOx), 36% of sulfur dioxide emitted, and 36% of all inhalable particulate matter (PM10) are emitted by the vehicular fleet. Concerning particles, 75% of the Fine Particle Concentration is related to the burning of fuel, mainly diesel. The fine particles are composed of Organic Carbon (40%), Black Carbon (30%), ions (15%) and metals. It is known that the soot is warming the climate and is important to the radiative balance. Another important driver to the radiative balance, the CO2 is mainly emitted by the transport sector, which is responsible for 57% of its emission. A comprehensive project under development has the objective of determine the role of MASP as the source of gaseous and particle compounds to the atmosphere of the region and in a mesoscale perspective. The project with funding from the São Paulo

  19. 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

  20. LCOE reduction for parabolic trough CSP: Innovative solar receiver with improved performance at medium temperature

    Science.gov (United States)

    Stollo, A.; Chiarappa, T.; D'Angelo, A.; Maccari, A.; Matino, F.

    2016-05-01

    Concentrated Solar Power (CSP) applications represent an effective possibility to gain energy from the Sun; however, the lasting CSP market crisis compels continuous improvements in terms of cost reduction and performance increase. Focused on parabolic trough technology, this paper describes the innovation studied and realized on solar receivers to gain optimized optical performance while increasing the production versatility, hence boosting the solar plant efficiency and finally reducing the estimated LCOE.

  1. SURFACE FINITE ELEMENTS FOR PARABOLIC EQUATIONS

    Institute of Scientific and Technical Information of China (English)

    G. Dziuk; C.M. Elliott

    2007-01-01

    In this article we define a surface finite element method (SFEM) for the numerical solution of parabolic partial differential equations on hypersurfaces Γ in (R)n+1. The key idea is based on the approximation of Γ by a polyhedral surface Γh consisting of a union of simplices (triangles for n = 2, intervals for n = 1) with vertices on Γ. A finite element space of functions is then defined by taking the continuous functions on Γh which are linear affine on each simplex of the polygonal surface. We use surface gradients to define weak forms of elliptic operators and naturally generate weak formulations of elliptic and parabolic equations on Γ. Our finite element method is applied to weak forms of the equations. The computation of the mass and element stiffness matrices are simple and straightforward.We give an example of error bounds in the case of semi-discretization in space for a fourth order linear problem. Numerical experiments are described for several linear and nonlinear partial differential equations. In particular the power of the method is demonstrated by employing it to solve highly nonlinear second and fourth order problems such as surface Allen-Cahn and Cahn-Hilliard equations and surface level set equations for geodesic mean curvature flow.

  2. Focusing parabolic guide for very small samples

    Energy Technology Data Exchange (ETDEWEB)

    Hils, T.; Boeni, P.; Stahn, J

    2004-07-15

    Modern materials can often only be grown in small quantities. Therefore, neutron-scattering experiments are difficult to perform due to the low signal. In order to increase the flux at the sample position, we have developed the concept of a small focusing guide tube with parabolically shaped walls that are coated with supermirror m=3. The major advantage of parabolic focusing is that the flux maximum occurs not at the exit of the tube. It occurs at the focal point that can be several centimeters away from the exit of the tube. We show that an intensity gain of 6 can easily be obtained. Simulations using the software package McStas demonstrate that gain factors up to more than 50 can be realised on a spot size of approximately 1.2 mm diameter. For PGAA we expect flux gains of up to three orders of magnitude if multiplexing is used. We show that elliptic ballistic guides lead to flux gains of more than 6.

  3. Focusing parabolic guide for very small samples

    Science.gov (United States)

    Hils, T.; Boeni, P.; Stahn, J.

    2004-07-01

    Modern materials can often only be grown in small quantities. Therefore, neutron-scattering experiments are difficult to perform due to the low signal. In order to increase the flux at the sample position, we have developed the concept of a small focusing guide tube with parabolically shaped walls that are coated with supermirror m=3. The major advantage of parabolic focusing is that the flux maximum occurs not at the exit of the tube. It occurs at the focal point that can be several centimeters away from the exit of the tube. We show that an intensity gain of 6 can easily be obtained. Simulations using the software package McStas demonstrate that gain factors up to more than 50 can be realised on a spot size of approximately 1.2 mm diameter. For PGAA we expect flux gains of up to three orders of magnitude if multiplexing is used. We show that elliptic ballistic guides lead to flux gains of more than 6.

  4. A nonlocal parabolic system with application to a thermoelastic problem

    Directory of Open Access Journals (Sweden)

    Y. Lin

    1999-01-01

    problem is first transformed into an equivalent nonlocal parabolic systems using a transformation, and then the existence and uniqueness of the solutions are demonstrated via the theoretical potential representation theory of the parabolic equations. Finally some realistic situations in the applications are discussed using the results obtained in this paper.

  5. Almost Periodic Viscosity Solutions of Nonlinear Parabolic Equations

    Directory of Open Access Journals (Sweden)

    Zhang Shilin

    2009-01-01

    Full Text Available We generalize the comparison result 2007 on Hamilton-Jacobi equations to nonlinear parabolic equations, then by using Perron's method to study the existence and uniqueness of time almost periodic viscosity solutions of nonlinear parabolic equations under usual hypotheses.

  6. Carleman Estimates for Parabolic Equations with Nonhomogeneous Boundary Conditions

    Institute of Scientific and Technical Information of China (English)

    Oleg Yu IMANUVILOV; Jean Pierre PUEL; Masahiro YAMAMOTO

    2009-01-01

    The authors prove a new Carleman estimate for general linear second order parabolic equation with nonhomogeneous boundary conditions.On the basis of this estimate,improved Carleman estimates for the Stokes system and for a system of parabolic equations with a penalty term are obtained.This system can be viewed as an approximation of the Stokes system.

  7. Flux form Semi-Lagrangian methods for parabolic problems

    CERN Document Server

    Bonaventura, Luca

    2015-01-01

    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 convergence analysis are proposed. Numerical examples validate the proposed method and display its potential for consistent semi-Lagrangian discretization of advection--diffusion and nonlinear parabolic problems.

  8. A numerical study of mixed parabolic-gradient systems

    NARCIS (Netherlands)

    Verwer, J.G.; Sommeijer, B.P.

    2000-01-01

    This paper is concerned with the numerical solution of parabolic equations coupled to gradient equations. The gradient equations are ordinary differential equations whose solutions define positions of particles in the spatial domain of the parabolic equations. The vector field of the gradient equati

  9. 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...

  10. STABILITY OF A PARABOLIC FIXED POINT OF REVERSIBLE MAPPINGS

    Institute of Scientific and Technical Information of China (English)

    LIUBIN; YOUJIANGONG

    1994-01-01

    KAM theorem of reversible system is used to provide a sufficient condition which guarantees the stability of a parabolic fixed point of reversible mappings, The main idea is to discuss when the parabolic fixed point is surrounded by closed invariant carves and thus exhibits stable behaviour.

  11. On the dynamics of a mixed parabolic-gradient system

    NARCIS (Netherlands)

    J.K. Krottje (Johannes)

    2002-01-01

    textabstractIn the current paper the dynamics of a mixed parabolic-gradient system is examined. Thesystem, which is a coupled system of parabolic equations and gradient equations, acts as a first model for the outgrowth of axons in a developing nervous system. For modeling considerations it is relev

  12. Manipulation of dielectric particles with nondiffracting parabolic beams.

    Science.gov (United States)

    Ortiz-Ambriz, Antonio; Gutiérrez-Vega, Julio C; Petrov, Dmitri

    2014-12-01

    The trapping and manipulation of microscopic particles embedded in the structure of nondiffracting parabolic beams is reported. The particles acquire orbital angular momentum and exhibit an open trajectory following the parabolic fringes of the beam. We observe an asymmetry in the terminal velocity of the particles caused by the counteracting gradient and scattering forces.

  13. Surface plasmon polariton beam focusing with parabolic nanoparticle chains

    DEFF Research Database (Denmark)

    Radko, Ilya P.; Bozhevolnyi, Sergey I.; Evlyukhin, Andrey B.

    2007-01-01

    We report on the focusing of surface plasmon polariton (SPP) beams with parabolic chains of gold nanoparticles fabricated on thin gold films. SPP focusing with different parabolic chains is investigated in the wavelength range of 700–860 nm, both experimentally and theoretically. Mapping of SPP...

  14. Polaron Energy and Effective Mass in Parabolic Quantum Wells

    Institute of Scientific and Technical Information of China (English)

    WANG Zhi-Ping; LIANG Xi-Xia

    2005-01-01

    @@ The energy and effective mass of a polaron in a parabolic quantum well are studied theoretically by using LLP-like transformations and a variational approach. Numerical results are presented for the polaron energy and effective mass in the GaAs/Al0.3Ga0.7As parabolic quantum well. The results show that the energy and the effective mass of the polaron both have their maxima in the finite parabolic quantum well but decrease monotonously in the infinite parabolic quantum well with the increasing well width. It is verified that the bulk longitudinal optical phonon mode approximation is an adequate formulation for the electron-phonon coupling in parabolic quantum well structures.

  15. Optical, Energetic and Exergetic Analyses of Parabolic Trough Collectors

    Institute of Scientific and Technical Information of China (English)

    (O)ZT(U)RK Murat; (C)(I)(C)EK BEZ(I)R Nalan; (O)ZEK Nuri

    2007-01-01

    Parabolic trough collectors generate thermal energy from solar energy. Especially, they are very convenient for applications in high temperature solar power systems. To determine the design parameters, parabolic trough collectors must be analysed with optical analysis. In addition, thermodynamics (energy and exergy) analysis in the development of an energy efficient system must be achieved. Solar radiation passes through Earth's atmosphere until it reaches on Earth's surface and is focused from the parabolic trough collector to the tube receiver with a transparent insulated envelope. All of them constitute a complex mechanism. We investigate the geometry of parabolic trough reflector and characteristics of solar radiation to the reflecting surface through Earth's atmosphere, and calculate the collecting total energy in the receiver. The parabolic trough collector,of which design parameters are given, is analysed in regard to the energy and exergy analysis considering the meteorological specification in May, June, July and August in Isparta/Turkey, and the results are presented.

  16. A source-orientated approach for estimating daytime concentrations of biogenic volatile organic compounds in an upper layer of a boreal forest canopy

    Energy Technology Data Exchange (ETDEWEB)

    Lappalainen, H.K. [Finnish Meteorological Inst., Helsinki (Finland); Sevanto, S.; Dal Maso, M.; Taipale, R.; Kajos, M. [Helsinki Univ. (Finland). Dept. of Physics; Kolari, P.; Back, J. [Helsinki Univ. (Finland). Dept. of Forest Ecology Sciences

    2013-06-01

    Biologically justified statistical models for daytime atmospheric concentrations of methanol, acetaldehyde, acetone, isoprene and monoterpene were tested using measurements at a boreal forest stand in southern Finland in 2006-2007 and in summer 2008. The canopy-scale concentrations of all compounds except monotepene were closely correlated with shoot-scale concentrations indicating a strong link to biological emission source. All the models were based on the exponential relationship between air temperature and atmospheric concentration of biogenic volatile organic compounds (BVOCs). The first model - an exponential function of air temperature (T model) - could explain 27%-64% of the variation in BVOC daytime concentrations in the test data. The second model - a Temperature-State of Development model (T-S model) having two explaining variables (air temperature and seasonal photosynthetic efficiency) - was derived from an empirical adjustment of seasonality. This model slightly increased the fraction of explained variation but it still could not explain the high concentration peaks, which accounted for most of the unexplained variation. To better analyse these peaks we tested the Trigger model including two potential environmental triggers, a PAR index (high photosynthetically active photon flux density (PAR) and high ozone concentration, that could increase the concentrations momentarily. However, the Trigger model described the peak concentrations only somewhat better than the T or T-S model. It seems that it is very difficult to explain more than 32%-67% of variation in BVOC concentrations by a straightforward source-oriented modelling without deep understanding of biological and physical processes. In order to improve the models profound studies on specific stress factors and events inducing BVOC emissions are needed. (orig.)

  17. Swelling and gel/sol formation of perchlorate-type layered double hydroxides in concentrated aqueous solutions of amino acid-related zwitterionic compounds.

    Science.gov (United States)

    Iyi, Nobuo; Ishihara, Shinsuke; Kaneko, Yoshiro; Yamada, Hirohisa

    2013-02-26

    ClO(4)(-)MgAl-LDH3, a MgAl (Mg/Al = 3) layered double hydroxide (LDH) containing perchlorate, swells and forms colloidal suspensions (sols) via the gel state in concentrated aqueous solutions of zwitterionic compounds related to amino acids. In total, 36 zwitterionic compounds with different molecular structures and additional functional groups were examined at various concentrations, and the sol-formation ability was judged by the transmittance (at λ = 589 nm) of the resulting suspensions. At low concentration, the obtained suspensions were turbid, with transmittances of ~0%. However, above the threshold concentration (0.3-1.0 M), osmotic swelling occurred and the transmittances of the suspensions increased sharply with increases in concentration to reach maximum values of 70-95%. The threshold concentration and maximum transmittance value depended on the structure and the location of the functional groups. The enhancement of the permittivity of water by the zwitterions and the formation of H-bond networks were assumed to be the reasons for the swelling phenomenon. Similar gel/sol formation was observed for ClO(4)(-)LDHs with Mg/Al = 2, Ni/Al = 2, 3, and Co/Al = 2 and some NO(3)(-)LDHs. Large ClO(4)(-)LDH films could be prepared by filtration of the colloidal suspensions followed by washing and drying processes.

  18. Distillate yield improvement using a parabolic dish reflector coupled single slope basin solar still with thermal energy storage using beeswax

    Directory of Open Access Journals (Sweden)

    Aondoyila KUHE

    2016-07-01

    Full Text Available A single slope solar still, integrated with latent heat thermal energy storage system coupled to a parabolic concentrator was designed with the aim of improving productivity. 14 kg of beeswax was used as phase change material (PCM between the absorber plate and the bottom of the still to keep the operating temperature of the still high enough to produce distilled water even during the sunset hours. The bottom of the still is covered by 0.2 m aluminum sheet painted black on the side facing the parabolic concentrator to help in absorbing solar radiation reflected from the parabolic concentrator and conducting same to the PCM. To determine the effect of PCM, a solar still without PCM was used to compare with the solar still with PCM. The temperature of water, air temperature, inner surface glass temperature and outer surface glass temperature were measured. Experimental results show that the effect of thermal storage in the parabolic concentrator-coupled single slope solar still increased the productivity by 62%.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1995-11-01

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

  20. Thin Film Flat Panel Off-Axis Solar Concentrator with Flux Distribution Project

    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...

  1. Expression of allelopathy in the soil environment: Soil concentration and activity of benzoxazinoid compounds released by rye cover crop residue

    Science.gov (United States)

    The activity of allelopathic compounds is often reduced in the soil environment where processes involving release from donor plant material, soil adsorption and degradation, and uptake by receptor plants naturally result in complex interactions. Rye (Secale cereale L.) cover crops are known to supp...

  2. Parabolic refined invariants and Macdonald polynomials

    CERN Document Server

    Chuang, Wu-yen; Donagi, Ron; Pantev, Tony

    2013-01-01

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

  3. Antireflection Pyrex envelopes for parabolic solar collectors

    Science.gov (United States)

    McCollister, H. L.; Pettit, R. B.

    1983-11-01

    Antireflective (AR) coatings, applied to the glass envelopes used in parabolic trough solar collectors around the receiver tube in order to reduce thermal losses, can increase solar transmittance by 7 percent. An AR surface has been formed on Pyrex by first heat treating the glass to cause a compositional phase separation, removing a surface layer after heat treatment through the use of a preetching solution, and finally etching in a solution that contains hydrofluorosilic and ammonium bifluoride acids. AR-coated samples with solar transmittance values of more than 0.97, by comparison to an untreated sample value of 0.91, have been obtained for the 560-630 C range of heat treatment temperatures. Optimum values have also been determined for the other processing parameters.

  4. Photon-Atom Coupling with Parabolic Mirrors

    CERN Document Server

    Sondermann, Markus

    2014-01-01

    Efficient coupling of light to single atomic systems has gained considerable attention over the past decades. This development is driven by the continuous growth of quantum technologies. The efficient coupling of light and matter is an enabling technology for quantum information processing and quantum communication. And indeed, in recent years much progress has been made in this direction. But applications aside, the interaction of photons and atoms is a fundamental physics problem. There are various possibilities for making this interaction more efficient, among them the apparently 'natural' attempt of mode-matching the light field to the free-space emission pattern of the atomic system of interest. Here we will describe the necessary steps of implementing this mode-matching with the ultimate aim of reaching unit coupling efficiency. We describe the use of deep parabolic mirrors as the central optical element of a free-space coupling scheme, covering the preparation of suitable modes of the field incident on...

  5. Analysis of the Quality of Parabolic Flight

    Science.gov (United States)

    Lambot, Thomas; Ord, Stephan F.

    2016-01-01

    Parabolic flight allows researchers to conduct several micro-gravity experiments, each with up to 20 seconds of micro-gravity, in the course of a single day. However, the quality of the flight environment can vary greatly over the course of a single parabola, thus affecting the experimental results. Researchers therefore require knowledge of the actual flight environment as a function of time. The NASA Flight Opportunities program (FO) has reviewed the acceleration data for over 400 parabolas and investigated the level of micro-gravity quality. It was discovered that a typical parabola can be segmented into multiple phases with different qualities and durations. The knowledge of the microgravity characteristics within the parabola will prove useful when planning an experiment.

  6. New method to solve electromagnetic parabolic equation

    Institute of Scientific and Technical Information of China (English)

    赵小峰; 黄思训; 康林春

    2013-01-01

    This paper puts forward a new method to solve the electromagnetic parabolic equation (EMPE) by taking the vertically-layered inhomogeneous characteristics of the atmospheric refractive index into account. First, the Fourier transform and the convo-lution theorem are employed, and the second-order partial differential equation, i.e., the EMPE, in the height space is transformed into first-order constant coefficient differential equations in the frequency space. Then, by use of the lower triangular characteristics of the coefficient matrix, the numerical solutions are designed. Through constructing ana-lytical solutions to the EMPE, the feasibility of the new method is validated. Finally, the numerical solutions to the new method are compared with those of the commonly used split-step Fourier algorithm.

  7. Preliminary degradation test of toxic compounds dissolved in water using concentrated solar light. Tecnologia solar de concentracion para eliminacion mediante fotocatalisis de residuos industriales toxicos disueltos en agua

    Energy Technology Data Exchange (ETDEWEB)

    Blanco galvez, J.; Malato Rogriguez, S.

    1992-01-01

    The production and emission of hazardous chemicals wastes is a problem that is becoming more and more important in the industrialized world. Most of these wastes are toxic organic compounds appearing in low concentration in the water. solar photocatalytic water detoxification using interaction between ultraviolet light and TiO[sub 2] catalyst has therefore a strong potential in the industrial destruction of toxic organics in water. (Author)

  8. Towards standardization of in-site parabolic trough collector testing in solar thermal power plants

    Science.gov (United States)

    Sallaberry, Fabienne; Valenzuela, Loreto; de Jalón, Alberto García; Leon, Javier; Bernad, Ignacio David

    2016-05-01

    This paper presents a summary of the testing procedure and a validation of the methodology of parabolic trough collector in solar thermal power plants. The applied testing methodology is the one proposed within the Spanish standardization sub-committee AEN/CTN 206/SC117 working group WG2 related to the components for solar thermal power plants. This methodology is also proposed within the international committee IEC TC 117 (Standard draft IEC 62862-3-2 Ed. 1.0). This study is done at Plataforma Solar de Almería (PSA) in Almeria within the European project STAGE-STE. This paper presents the results of the optical and thermal efficiency of a large-size parabolic trough collector. The obtained values are similar to the previous analysis on this collector by PSA. The results of the tracking system have a good accuracy compared to the acceptance angle of the concentrator.

  9. Strong coupling and stimulated emission in single parabolic quantum well microcavity for terahertz cascade

    Energy Technology Data Exchange (ETDEWEB)

    Tzimis, A.; Savvidis, P. G. [Department of Materials Science and Technology, University of Crete, 71003 Heraklion, Crete (Greece); Institute of Electronic Structure and Laser, Foundation for Research and Technology - Hellas, 71110 Heraklion, Crete (Greece); Trifonov, A. V.; Ignatiev, I. V. [Spin Optics Laboratory, State University of Saint-Petersburg, 1 Ulianovskaya, 198504 St. Petersburg (Russian Federation); Christmann, G.; Tsintzos, S. I. [Institute of Electronic Structure and Laser, Foundation for Research and Technology - Hellas, 71110 Heraklion, Crete (Greece); Hatzopoulos, Z. [Institute of Electronic Structure and Laser, Foundation for Research and Technology - Hellas, 71110 Heraklion, Crete (Greece); Department of Physics, University of Crete, 71003 Heraklion, Crete (Greece); Kavokin, A. V. [Spin Optics Laboratory, State University of Saint-Petersburg, 1 Ulianovskaya, 198504 St. Petersburg (Russian Federation); School of Physics and Astronomy, University of Southampton, Southampton SO17 1BJ (United Kingdom)

    2015-09-07

    We report observation of strong light-matter coupling in an AlGaAs microcavity (MC) with an embedded single parabolic quantum well. The parabolic potential is achieved by varying aluminum concentration along the growth direction providing equally spaced energy levels, as confirmed by Brewster angle reflectivity from a reference sample without MC. It acts as an active region of the structure which potentially allows cascaded emission of terahertz (THz) light. Spectrally and time resolved pump-probe spectroscopy reveals characteristic quantum beats whose frequencies range from 0.9 to 4.5 THz, corresponding to energy separation between relevant excitonic levels. The structure exhibits strong stimulated nonlinear emission with simultaneous transition to weak coupling regime. The present study highlights the potential of such devices for creating cascaded relaxation of bosons, which could be utilized for THz emission.

  10. Sener Parabolic trough Collector Design and Testing

    Energy Technology Data Exchange (ETDEWEB)

    Castaneda, N.; Vazquez, J.; Domingo, M.

    2006-07-01

    Parabolic trough technology is nowadays the most extended solar system for electricity production or steam generation for industrial processes. It is basically composed of a collector field which converts solar irradiation into thermal energy- and a conventional thermal-toelectric conversion Rankine cycle. In these plants, a storage system can be implemented in order to increase plant production. Collector field represents more than half the total plant cost. Therefore, SENER has made an effort to improve current state of the art of parabolic trough collector (PTC from now on) design in order to reduce plant costs. Main characteristic of SENER design lies on the use of a torque tube as the central body of the collector. This tube is made of steel sheet, with a thickness depending on wind load requirements on the collector. This concept is very cost-effective, since the man-power needed to manufacture the tube has been minimized. Continuous cylindrical shape of the torque tube provides a high torsional stiffness, which is one of the main parameters affecting collector optical efficiency. Cantilever arms connect the mirrors to the central torque tube. These components are usually made of welded tube profiles. In SENER's new design, these cantilever arms are made using metal sheet stamping techniques (SENER patent), thus reducing manufacturing and mounting costs. SENER PTC module (called SENERTROUGH) is 12 meters long and has an aperture width of 5,76 m. HCE and curved mirrors existing in the market - as well as new products from different manufacturers - can be easily attached to collector structure. Two prototype modules of SENERTROUGH have been mounted and tested at the CIEMAT-PSA facilities. Several performance tests were performed in order to assure the validity of the concept. (Author)

  11. Feasibility of a tandem photocatalytic oxidation-adsorption system for removal of monoaromatic compounds at concentrations in the sub-ppm-range.

    Science.gov (United States)

    Jo, Wan-Kuen; Yang, Chang-Hee

    2009-09-01

    Unlike previous photocatalytic oxidation (PCO) studies incorporated with adsorption, this study investigates the feasibility of applying a tandem PCO-adsorption hybrid technique regarding low-level monoaromatic compound removal. The PCO efficiencies decreased as the hydraulic diameter (HD) increased. A PCO reactor of a medium HD size was selected for further experiments. Under conditions relevant to the use of the PCO system, the CO level measured during the PCO process was minimal in comparison to indoor CO levels. Trace level formations of formaldehyde and acetaldehyde were observed during the photocatalytic process, but these compounds were undetectable at the activated carbon unit outlet. The degradation efficiencies, obtained from the PCO unit, exhibited a dependence on both the inlet concentration (IC) and relative humidity (RH), whereas those from the PCO-adsorption hybrid system did not. Under specific conditions, the PCO unit presented a high degradation efficiency of close to, or exceeding 90%, in regards to ethyl benzene, o-xylene, and m,p-xylene. However, the benzene air concentrations, after being treated by the PCO unit, substantially exceeded the USEPA inhalation reference concentration guideline of 30microgm(-3) (corresponding to 0.01ppm). In contrast, the PCO-adsorption hybrid system presented a high removal efficiency of close to 100% regarding all compounds, regardless of the IC or RH range. Consequently, it is suggested that the PCO-adsorption hybrid system has a synergistic advantage of photocatalysis and adsorption in regards to the BTEX elimination process.

  12. A Comparison Study of Volatile Organic Compound Species and Concentrations in Snow Samples From Rural Sites in South-Western Quebec and at Alert, Nunavut

    Science.gov (United States)

    Mortazavi, R.; Kos, G.; Ariya, P. A.

    2006-12-01

    An intercomparison study was undertaken to evaluate volatile organic compound (VOC) species and concentrations in snow from different environments. Samples were collected in semi-urban/rural environments in Montreal, south-western Quebec, approximately 50 and 150 km east and north of Montreal, Quebec. Samples were also collected in the High Arctic near Alert, Nunavut. Analysis was carried out using pre- concentration with solid phase micro-extraction (SPME) and subsequent analyses using gas chromatography systems fitted with mass spectrometric (GC/MS) and flame ionisation detectors (GC/FID). Headspace and liquid phase of the snow samples were analysed. Bacterial and fungal species were isolated from sampled snow and their ice nucleation ability was assessed. Results demonstrate how VOC species and concentrations vary with the degree of anthropogenic activity and how long-range transport causes anthropogenic compounds to get deposited in the snow pack of remote areas. It is also shown, that snow provides a reservoir of various photo-labile compounds, and serves as an active site for microbiological processes. Atmospheric implications of the results will be discussed.

  13. Characterizing baseline concentrations, proportions, and processes controlling deposition of river-transported bitumen-associated polycyclic aromatic compounds at a floodplain lake (Slave River Delta, Northwest Territories, Canada).

    Science.gov (United States)

    Elmes, Matthew C; Wiklund, Johan A; Van Opstal, Stacey R; Wolfe, Brent B; Hall, Roland I

    2016-05-01

    Inadequate knowledge of baseline conditions challenges ability for monitoring programs to detect pollution in rivers, especially where there are natural sources of contaminants. Here, we use paleolimnological data from a flood-prone lake ("SD2", informal name) in the Slave River Delta (SRD, Canada), ∼ 500 km downstream of the Alberta oil sands development and the bitumen-rich McMurray Formation to identify baseline concentrations and proportions of "river-transported bitumen-associated indicator polycyclic aromatic compounds" (indicator PACs; Hall et al. 2012) and processes responsible for their deposition. Results show that indicator PACs are deposited in SD2 by Slave River floodwaters in concentrations that are 45 % lower than those in sediments of "PAD31compounds", a lake upstream in the Athabasca Delta that receives Athabasca River floodwaters. Lower concentrations at SD2 are likely a consequence of sediment retention upstream as well as dilution by sediment influx from the Peace River. In addition, relations with organic matter content reveal that flood events dilute concentrations of indicator PACs in SD2 because the lake receives high-energy floods and the lake sediments are predominantly inorganic. This contrasts with PAD31 where floodwaters increase indicator PAC concentrations in the lake sediments, and concentrations are diluted during low flood influence intervals due to increased deposition of lacustrine organic matter. Results also show no significant differences in concentrations and proportions of indicator PACs between pre- (1967) and post- (1980s and 1990 s) oil sands development high flood influence intervals (t = 1.188, P = 0.279, d.f. = 6.136), signifying that they are delivered to the SRD by natural processes. Although we cannot assess potential changes in indicator PACs during the past decade, baseline concentrations and proportions can be used to enhance ongoing monitoring efforts.

  14. Comparison of Pumped and Diffusion Sampling Methods to Monitor Concentrations of Perchlorate and Explosive Compounds in Ground Water, Camp Edwards, Cape Cod, Massachusetts, 2004-05

    Science.gov (United States)

    LeBlanc, Denis R.; Vroblesky, Don A.

    2008-01-01

    Laboratory and field tests were conducted at Camp Edwards on the Massachusetts Military Reservation on Cape Cod to examine the utility of passive diffusion sampling for long-term monitoring of concentrations of perchlorate and explosive compounds in ground water. The diffusion samplers were constructed of 1-inch-diameter rigid, porous polyethylene tubing. The results of laboratory tests in which diffusion samplers were submerged in containers filled with ground water containing perchlorate, RDX (hexahydro-1,3,5-trinitro-1,3,5-triazine), and HMX (octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine) indicate that concentrations inside the diffusion samplers equilibrated with concentrations in the containers within the 19-day-long test period. Field tests of the diffusion samplers were conducted in 15 wells constructed of 2- or 2.5-inch-diameter polyvinyl chloride pipe with 10-foot-long slotted screens. Concentrations of perchlorate, RDX, and HMX in the diffusion samplers placed in the wells for 42 to 52 days were compared to concentrations in samples collected by low-flow pumped sampling from 53 days before to 109 days after retrieval of the diffusion samples. The results of the field tests indicate generally good agreement between the pumped and diffusion samples for concentrations of perchlorate, RDX, and HMX. The concentration differences indicate no systematic bias related to contaminant type or concentration levels.

  15. Comparison of the concentrations of phenolic compounds in olive oils and other plant oils: correlation with antimicrobial activity.

    Science.gov (United States)

    Medina, Eduardo; de Castro, Antonio; Romero, Concepcion; Brenes, Manuel

    2006-07-12

    The antimicrobial activity of different edible vegetable oils was studied. In vitro results revealed that the oils from olive fruits had a strong bactericidal action against a broad spectrum of microorganisms, this effect being higher in general against Gram-positive than Gram-negative bacteria. Thus, olive oils showed bactericidal activity not only against harmful bacteria of the intestinal microbiota (Clostridium perfringens and Escherichia coli) also against beneficial microorganisms such as Lactobacillus acidophilus and Bifidobacterium bifidum. Otherwise, most of the foodborne pathogens tested (Listeria monocytogenes, Staphylococcus aureus, Salmonella enterica, Yersinia sp., and Shigella sonnei) did not survive after 1 h of contact with olive oils. The dialdehydic form of decarboxymethyl oleuropein and ligstroside aglycons, hydroxytyrosol and tyrosol, were the phenolic compounds that statistically correlated with bacterial survival. These findings were confirmed by testing each individual phenolic compound, isolated by HPLC, against L. monocytogenes. In particular, the dialdehydic form of decarboxymethyl ligstroside aglycon showed a potent antimicrobial activity. These results indicate that not all oils classified as "olive oil" had similar bactericidal effects and that this bioactivity depended on their content of certain phenolic compounds.

  16. 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.

  17. 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.

  18. Parabolic Trough Photovoltaic/Thermal Collectors: Design and Simulation Model

    Directory of Open Access Journals (Sweden)

    Laura Vanoli

    2012-10-01

    Full Text Available This paper presents a design procedure and a simulation model of a novel concentrating PVT collector. The layout of the PVT system under investigation was derived from a prototype recently presented in literature and commercially available. The prototype consisted in a parabolic trough concentrator and a linear triangular receiver. In that prototype, the bottom surfaces of the receiver are equipped with mono-crystalline silicon cells whereas the top surface is covered by an absorbing surface. The aperture area of the parabola was covered by a glass in order to improve the thermal efficiency of the system. In the modified version of the collector considered in this paper, two changes are implemented: the cover glass was eliminated and the mono-crystalline silicon cells were replaced by triple-junction cells. In order to analyze PVT performance, a detailed mathematical model was implemented. This model is based on zero-dimensional energy balances. The simulation model calculates the temperatures of the main components of the system and the main energy flows Results showed that the performance of the system is excellent even when the fluid temperature is very high (>100 °C. Conversely, both electrical and thermal efficiencies dramatically decrease when the incident beam radiation decreases.

  19. Winston Solar Concentrators and Evaluation Support. Phase 2: Non-imaging Concentrators for Space Applications

    Science.gov (United States)

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

    1978-01-01

    A 4.67X, plus or minus 5 deg. compound parabolic concentrator (CPC) for a large photovoltaic array in space was analyzed. The design was demonstrated to be effective in achieving a net power gain which can be varied from more than a factor of 3 down to approximately unity. A method for reducing nonuniformities in illumination to a given desired level was found. The effectiveness of this method, which involves the introduction of a degree of non-specularity in the reflector surface, was confirmed by direct measurements with prepared foil reflectors in a CPC in terrestrial sunshine as well as by computer ray tracing. Further ray tracing confirms that the CPC design is extremely tolerant to pointing and alignment errors, minor distortions, etc. A two stage non-imaging design was shown, by preliminary measurements and analysis, to provide both the desired angular tolerance and the required degree of intensity uniformity if higher concentrations (4X-10X) are necessary.

  20. Assessment of the antioxidant activity of Bifurcaria bifurcata aqueous extract on canola oil. Effect of extract concentration on the oxidation stability and volatile compound generation during oil storage.

    Science.gov (United States)

    Agregán, Rubén; Lorenzo, José M; Munekata, Paulo E S; Dominguez, Ruben; Carballo, Javier; Franco, Daniel

    2017-09-01

    In this research the antioxidant activity of water extracts of Bifurcaria bifurcata (BBE) at different dose against butylated hydroxytoluene (BHT) was evaluated in canola oil. Water extracts were firstly characterized in terms of total solid and polyphenolic compound contents, and their antioxidant activity together with that of BHT was evaluated using several in vitro tests (DPPH, ABTS, ORAC and FRAP). Next, the progress of lipid oxidation was assessed in canola oil added with five BBE concentrations (200, 400, 600, 800 and 1000ppm) and two BHT concentrations (50 and 200ppm) using an accelerated oxidation test. The progress in lipid oxidation was monitored by assessing some chemical indices (peroxide value, p-anisidine value, and conjugated dienes) during oil storage and some volatile compounds at the end of the storage period. BBE showed a significant antioxidant effect, being this ability concentration-dependent. The extent of lipid oxidation was inversely related to BBE dose, specially with regard to primary oxidation products. At the highest level of BBE, significant decreases of primary and secondary oxidation products, with respect to the control, were obtained with reduction percentages of 71.53%, 72.78%, 68.17% and 71.3% for peroxides, conjugated dienes, p-anisidine and TOTOX values, respectively. A level of 600ppm or higher concentration of the extract inhibits the lipid oxidation in a similar way than BHT at 200ppm. Regarding the inhibition of the formation of volatile compounds, both BBE and BHT strongly inhibited the formation of volatiles during oil storage, being this inhibition similar for all the concentrations of BBE and BHT essayed. Overall, results indicated that BBE can be used as a potential natural additive for improving oxidative stability of canola oil. Copyright © 2016 Elsevier Ltd. All rights reserved.

  1. Gas-phase naphthalene concentration data recovery in ambient air and its relevance as a tracer of sources of volatile organic compounds

    Science.gov (United States)

    Uria-Tellaetxe, Iratxe; Navazo, Marino; de Blas, Maite; Durana, Nieves; Alonso, Lucio; Iza, Jon

    2016-04-01

    Despite the toxicity of naphthalene and the fact that it is a precursor of atmospheric photooxidants and secondary aerosol, studies on ambient gas-phase naphthalene are generally scarce. Moreover, as far as we are concerned, this is the first published one using long-term hourly ambient gas-phase naphthalene concentrations. In this work, it has been also demonstrated the usefulness of ambient gas-phase naphthalene to identify major sources of volatile organic compounds (VOC) in complex scenarios. Initially, in order to identify main benzene emission sources, hourly ambient measurements of 60 VOC were taken during a complete year together with meteorological data in an urban/industrial area. Later, due to the observed co-linearity of some of the emissions, a procedure was developed to recover naphthalene concentration data from recorded chromatograms to use it as a tracer of the combustion and distillation of petroleum products. The characteristic retention time of this compound was determined comparing previous GC-MS and GC-FID simultaneous analysis by means of relative retention times, and its concentration was calculated by using relative response factors. The obtained naphthalene concentrations correlated fairly well with ethene (r = 0.86) and benzene (r = 0.92). Besides, the analysis of daily time series showed that these compounds followed a similar pattern, very different from that of other VOC, with minimum concentrations at day-time. This, together with the results from the assessment of the meteorological dependence pointed out a coke oven as the major naphthalene and benzene emitting sources in the study area.

  2. Parabolic Bundles on Algebraic Surfaces I -- The Donaldson-Uhlenbeck Compactification

    Indian Academy of Sciences (India)

    V Balaji; A Dey; R Parthasarathi

    2008-02-01

    The aim of this paper is to construct the parabolic version of the Donaldson-Uhlenbeck compactification for the moduli space of parabolic stable bundles on an algebraic surface with parabolic structures along a divisor with normal crossing singularities. We prove the non-emptiness of the moduli space of parabolic stable bundles of rank 2.

  3. A Microscopic Convexity Principle for Spacetime Convex Solutions of Fully Nonlinear Parabolic Equations

    Institute of Scientific and Technical Information of China (English)

    Chuan Qiang CHEN; Bo Wen HU

    2013-01-01

    We study microscopic spacetime convexity properties of fully nonlinear parabolic partial differential equations.Under certain general structure condition,we establish a constant rank theorem for the spacetime convex solutions of fully nonlinear parabolic equations.At last,we consider the parabolic convexity of solutions to parabolic equations and the convexity of the spacetime second fundamental form of geometric flows.

  4. Effect of non-surgical periodontal therapy on the concentration of volatile sulfur compound in mouth air of a group of nigerian young adults.

    Science.gov (United States)

    Ehizele, Ao; Akhionbare, O

    2013-07-01

    The major goal of non-surgical periodontal therapy is to reduce or eliminate the subgingival pathogenic microbial flora that is known to be associated with volatile sulfur compounds (VSC). The aim of this study was, therefore, to determine the effect of non-surgical periodontal therapy on the concentration of VSC in mouth air of young adults. Four hundred subjects, grouped into two based on the absence or presence of periodontal diseases, were involved in this study. Basic periodontal examination was used for the grouping. The measurement of the concentration of the VSC in the mouth air of the subjects was done objectively, using the Halimeter, before and after the therapy, and at recall visits 2 weeks and 6 weeks after therapy. Chi-square and Paired t-test were used to find statistical significance. The results revealed that at baseline, 78.7% (48/61) of the subjects who had VSC concentration more than 250 parts per billion (ppb) were from the group with periodontal disease. Immediately after non-surgical periodontal therapy, only 8.5% (17/200) of the subjects with periodontal disease had VSC concentration of more than 250 ppb while all the subjects with no periodontal disease had VSC concentration less than 181 ppb. The same pattern of reduction in the concentration of the VSC and improvement in oral hygiene was also obtained 2 weeks and 6 weeks after therapy. It can be concluded that non-surgical periodontal therapy brought about reduction in the concentration of volatile sulfur compounds in mouth air of young adults.

  5. Micellar electrokinetic chromatography of aromatic anions and non-ionic aromatic compounds with stepwise changes of the concentration of cetyltrimethylammonium chloride.

    Science.gov (United States)

    Esaka, Yukihiro; Kobayashi, Miki; Murakami, Hiroya; Uno, Bunji

    2012-05-04

    Micellar electrokinetic chromatography in which the concentration of cetyltrimetylammmonium chloride (CTAC) was sequentially changed in the separation system was investigated using 10 aromatic anions and 11 non-ionic aromatic compounds as model analytes. All separations were performed in the absence of electroosmotic flow (EOF), and thus, analytes were detected in the order of their strength of interaction with micelles in the system. In isocratic elutions without EOF, the model analytes could be separated better with lower concentrations of CTAC but migration times of the analytes possessing relatively higher polarities increased markedly, and thus, long analysis times were required. Therefore, we attempted to increase the concentration of CTAC during a single measurement to reduce the analysis time without hindering the resultant separation of analytes obtained with lower concentrations. Briefly, the present surfactant stepwise elution can be performed by a sequential increase in CTAC concentrations of the running solution in the anodic reservoir from 30 to 50mM for the anions and from 20 to 50 mM for the non-ionic compounds. Additionally, to perform expected gradient separations with good reproducibility, each running solution with a different CTAC concentration was treated with tetraethylammmonium chloride as an additive to adjust electric conductivities of each running solution to be equal. Under this condition, CTAC micelles of each zone of different CTAC concentrations would migrate with practically the same velocity. Consequently, by the present stepwise method, both the 10 anionic analytes and the 11 non-ionic analytes were well separated within reasonable periods which corresponded approximately to two-third and less than half of those by the isocratic elutions, respectively.

  6. Sun batteries module based on А3В5 compounds with concentrators of sun energy and system of heatsink

    Directory of Open Access Journals (Sweden)

    Vakiv M.

    2010-03-01

    Full Text Available Characteristics of technology of manufacturing epitaxial structures GaAs(AlGaAs/InGaP with two active p–n-junctions for photocells which are able to work at concentrated solar radiation are considered. New suitable for industry technology of manufacturing and structure of solar batteries module based on epitaxial structures GaAs with Fresnel lens as concentrators of solar energy and a heat sink on the base of a heat pipe, equipped with a radiator sheet are developed. In conditions of 500-fold concentration of natural solar illumination at AM1,5 and 27,8% COE of a photocell, the electric power that is generated by the module reaches 78 Vt.

  7. Offset semi-parabolic nanoantenna made of a photonic crystal parabolic mirror and a plasmonic bow-tie antenna.

    Science.gov (United States)

    Hattori, Haroldo T

    2014-10-10

    In a parabolic mirror, light coming parallel to the antenna passes through its focal point. In this work, a waveguide feeds a semi-parabolic photonic crystal mirror and the emerging beam feeds a bow-tie antenna placed at the mirror's focal point-it is shown that the antenna system can not only feed a bow-tie antenna (producing a localized moderately high electric field) but also produces a directional radiation beam. The semi-parabolic mirror is also modified to reduce reflection back to the feeding waveguide.

  8. Recent (2008-10) concentrations and isotopic compositions of nitrate and concentrations of wastewater compounds in the Barton Springs zone, south-central Texas, and their potential relation to urban development in the contributing zone

    Science.gov (United States)

    Mahler, Barbara J.; Musgrove, MaryLynn; Herrington, Chris; Sample, Thomas L.

    2011-01-01

    During 2008–10, the U.S. Geological Survey, in cooperation with the City of Austin, the City of Dripping Springs, the Barton Springs/Edwards Aquifer Conservation District, the Lower Colorado River Authority, Hays County, and Travis County, collected and analyzed water samples from five streams (Barton, Williamson, Slaughter, Bear, and Onion Creeks), two groundwater wells (Marbridge well [YD–58–50–704] and Buda well [LR–58–58–403]), and the main orifice of Barton Springs in Austin, Texas, with the objective of characterizing concentrations and isotopic compositions of nitrate and concentrations of wastewater compounds in the Barton Springs zone. The Barton Springs zone is in south-central Texas, an area undergoing rapid growth in population and in land area affected by development, with associated increases in wastewater generation. Over a period of 17 months, during which the hydrologic conditions transitioned from dry to wet, samples were collected routinely from the streams, wells, and spring and, in response to storms, from the streams and spring; some or all samples were analyzed for nitrate, nitrogen and oxygen isotopes of nitrate, and waste­water compounds. The median nitrate concentrations in routine samples from all sites were higher in samples collected during the wet period than in samples collected during the dry period, with the greatest difference for stream samples (0.05 milligram per liter during the dry period to 0.96 milligram per liter for the wet period). Nitrate concentrations in recent (2008–10) samples were elevated relative to concentrations in historical (1990–2008) samples from streams and from Barton Springs under medium- and high-flow conditions. Recent nitrate concentrations were higher than historical concentrations at the Marbridge well but the reverse was true at the Buda well. The elevated concentrations likely are related to the cessation of dry conditions coupled with increased nitrogen loading in the

  9. Impact of Species and Variety on Concentrations of Minor Lipophilic Bioactive Compounds in Oils Recovered from Plum Kernels.

    Science.gov (United States)

    Górnaś, Paweł; Rudzińska, Magdalena; Raczyk, Marianna; Mišina, Inga; Soliven, Arianne; Lācis, Gunārs; Segliņa, Dalija

    2016-02-01

    The profile of bioactive compounds (carotenoids, tocopherols, tocotrienols, phytosterols, and squalene) in oils recovered from the kernels of 28 plum varieties of hexaploid species Prunus domestica L. and diploid plums Prunus cerasifera Ehrh. and their crossbreeds were studied. Oil yields in plum kernels of both P. cerasifera and P. domestica was in wide ranges of 22.6-53.1 and 24.2-46.9% (w/w) dw, respectively. The contents of total tocochromanols, carotenoids, phytosterols, and squalene was significantly affected by the variety and ranged between 70.7 and 208.7 mg/100 g of oil, between 0.41 and 3.07 mg/100 g of oil, between 297.2 and 1569.6 mg/100 g of oil, and between 25.7 and 80.4 mg/100 g of oil, respectively. Regardless of the cultivar, β-sitosterol and γ-tocopherol were the main minor lipophilic compounds in plum kernel oils and constituted between 208.5 and 1258.7 mg/100 g of oil and between 60.5 and 182.0 mg/100 g of oil, respectively. Between the studied plum species, significant differences were recorded for δ-tocopherol (p = 0.007), 24-methylenecycloartanol (p = 0.038), and citrostadienol (p = 0.003), but they were insufficient for discrimination by PCA.

  10. Identification of some factors affecting pharmaceutical active compounds (PhACs) removal in real wastewater. Case study of fungal treatment of reverse osmosis concentrate.

    Science.gov (United States)

    Badia-Fabregat, Marina; Lucas, Daniel; Gros, Meritxell; Rodríguez-Mozaz, Sara; Barceló, Damià; Caminal, Glòria; Vicent, Teresa

    2015-01-01

    Many technologies are being developed for the efficient removal of micropollutants from wastewater and, among them, fungal degradation is one of the possible alternative biological treatments. In this article, some factors that might affect pharmaceutically active compounds (PhACs) removal in a fungal treatment of real wastewater were identified in batch bioreactor treating reverse osmosis concentrate (ROC) from urban wastewater treatment plant (WWTP). We found that degradation of PhACs by Trametes versicolor was enhanced by addition of external nutrients (global removal of 44%). Moreover, our results point out that high aeration might be involved in the increase in the concentration of some PhACs. In fact, conjugation and deconjugation processes (among others) affect the removal assessment of emerging contaminants when working with real concentrations in comparison to experiments with spiked samples. Moreover, factors that could affect the quantification of micropollutants at lab-scale experiments were studied.

  11. Fungal treatment for the removal of endocrine disrupting compounds from reverse osmosis concentrate: Identification and monitoring of transformation products of benzotriazoles.

    Science.gov (United States)

    Llorca, Marta; Badia-Fabregat, Marina; Rodríguez-Mozaz, Sara; Caminal, Glòria; Vicent, Teresa; Barceló, Damià

    2017-10-01

    The removal of 27 endocrine-disrupting compounds and related compounds (suspect effect) from a reverse osmosis concentrate using an alternative decontamination method based on a fungal treatment involving Trametes versicolor was assessed. In addition to chemical analysis, the toxicity of the treated water during the treatment was monitored using a bioluminescence inhibition test and estrogenic and anti-estrogenic tests. The compounds 1H-benzotriazole (BTZ) and two tolyltriazoles (TTZs), 4-methyl-1H-benzotriazole (4-MBTZ) and 5-methyl-1H-benzotriazole (5-MBTZ), were present in the reverse osmosis concentrate at the highest concentrations (7.4 and 12.8 μg L(-1), respectively) and were partially removed by the fungal treatment under sterile conditions (58% for BTZ and 92% for TTZs) and non-sterile conditions, although to lesser extents (32% for BTZ and 50% for TTZs). Individual biotransformation studies of BTZ and the TTZs by T. versicolor in a synthetic medium and further analysis via on-line turbulent flow chromatography coupled to an HRMS-Orbitrap allowed the tentative identification of the transformation products (TPs). Six TPs were postulated for BTZ, two TPs were postulated for 4-MBTZ, and four TPs were postulated for 5-MBTZ. Most of these TPs are suggested to have been generated by conjugation with some sugars and via the methylation of the triazole group. Only TP 148 A, postulated to be derived from the biotransformation of BTZ, was observed in the effluent of the bioreactor treating the reverse osmosis concentrate. Copyright © 2017 Elsevier Ltd. All rights reserved.

  12. Examining the response of needle carbohydrates from Siberian larch trees to climate using compound-specific δ(13) C and concentration analyses.

    Science.gov (United States)

    Rinne, K T; Saurer, M; Kirdyanov, A V; Bryukhanova, M V; Prokushkin, A S; Churakova Sidorova, O V; Siegwolf, R T W

    2015-11-01

    Little is known about the dynamics of concentrations and carbon isotope ratios of individual carbohydrates in leaves in response to climatic and physiological factors. Improved knowledge of the isotopic ratio in sugars will enhance our understanding of the tree ring isotope ratio and will help to decipher environmental conditions in retrospect more reliably. Carbohydrate samples from larch (Larix gmelinii) needles of two sites in the continuous permafrost zone of Siberia with differing growth conditions were analysed with the Compound-Specific Isotope Analysis (CSIA). We compared concentrations and carbon isotope values (δ(13) C) of sucrose, fructose, glucose and pinitol combined with phenological data. The results for the variability of the needle carbohydrates show high dynamics with distinct seasonal characteristics between and within the studied years with a clear link to the climatic conditions, particularly vapour pressure deficit. Compound-specific differences in δ(13) C values as a response to climate were detected. The δ(13) C of pinitol, which contributes up to 50% of total soluble carbohydrates, was almost invariant during the whole growing season. Our study provides the first in-depth characterization of compound-specific needle carbohydrate isotope variability, identifies involved mechanisms and shows the potential of such results for linking tree physiological responses to different climatic conditions.

  13. Pseudo almost periodic solutions to parabolic boundary value inverse problems

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    We first define the pseudo almost periodic functions in a more general setting.Then we show the existence,uniqueness and stability of pseudo almost periodic solutions of parabolic inverse problems for a type of boundary value problems.

  14. OSCILLATION OF NONLINEAR IMPULSIVE PARABOLIC DIFFERENTIAL EQUATIONS WITH SEVERAL DELAYS

    Institute of Scientific and Technical Information of China (English)

    CuiChenpei; ZouMin; LiuAnping; XiaoLi

    2005-01-01

    In this paper, oscillatory properties for solutions of certain nonlinear impulsive parabolic equations with several delays are investigated and a series of new sufficient conditions for oscillations of the equation are established.

  15. A Note about Parabolic Systems and Analytic Semigroups

    Institute of Scientific and Technical Information of China (English)

    STR?HMER Gerhard

    2011-01-01

    We investigate the question whether certain parabolic systems in the sense of Petrovskii fulfill the resolvent estimate required for the generation of an analytic semigroup and apply the result to a problem concerning the diffusion of gases.

  16. A SINGLE STEP SCHEME WITH HIGH ACCURACY FOR PARABOLIC PROBLEM

    Institute of Scientific and Technical Information of China (English)

    陈传淼; 胡志刚

    2001-01-01

    A single step scheme with high accuracy for solving parabolic problem is proposed. It is shown that this scheme possesses good stability and fourth order accuracy with respect to both time and space variables, which are superconvergent.

  17. Parabolic Equations in Musielak-Orlicz-Sobolev Spaces

    Directory of Open Access Journals (Sweden)

    M.L. Ahmed Oubeid

    2013-11-01

    Full Text Available We prove in this paper the existence of solutions of nonlinear parabolic problems in Musielak-Orlicz-Sobolev spaces. An approximation and a trace results in inhomogeneous Musielak-Orlicz-Sobolev spaces have also been provided.

  18. HYPERBOLIC-PARABOLIC CHEMOTAXIS SYSTEM WITH NONLINEAR PRODUCT TERMS

    Institute of Scientific and Technical Information of China (English)

    Chen Hua; Wu Shaohua

    2008-01-01

    We prove the local existence and uniqueness of week solution of the hyperbolic-parabolic Chemotaxis system with some nonlinear product terms. For one dimensional case, we prove also the global existence and uniqueness of the solution for the problem.

  19. An X-band parabolic antenna based on gradient metasurface

    Energy Technology Data Exchange (ETDEWEB)

    Yao, Wang; Yang, Helin, E-mail: emyang@mail.ccnu.edu.cn; Tian, Ying; Guo, Linyan [College of Physical Science and Technology, Central China Normal University, Wuhan 430079 (China); Huang, Xiaojun [College of Physical Science and Technology, Central China Normal University, Wuhan 430079 (China); College of physics and electrical engineering, Kashgar University, Kashgar, 844000 (China)

    2016-07-15

    We present a novel parabolic antenna by employing reflection gradient metasurface which is composed of a series of circle patches on a grounded dielectric substrate. Similar to the traditional parabolic antenna, the proposed antenna take the metasurface as a “parabolic reflector” and a patch antenna was placed at the focal point of the metasurface as a feed source, then the quasi-spherical wave emitted by the source is reflected and transformed to plane wave with high efficiency. Due to the focus effect of reflection, the beam width of the antenna has been decreased from 85.9° to 13° and the gain has been increased from 6.5 dB to 20.8 dB. Simulation and measurement results of both near and far-field plots demonstrate good focusing properties of the proposed parabolic antenna.

  20. On Doubly Degenerate Quasilinear Parabolic Equations of Higher Order

    Institute of Scientific and Technical Information of China (English)

    Zhen Hai LIU

    2005-01-01

    We deal with the existence of periodic solutions for doubly degenerate quasilinear parabolic equations of higher order, which can degenerate, on a part of the boundary, on a segment in the interior of the domain and in time.

  1. Homogenization of attractors for a class of nonlinear parabolic equations

    Institute of Scientific and Technical Information of China (English)

    WANG Guo-lian; ZHANG Xing-you

    2004-01-01

    The relation between the global attractors Aε for a calss of quasilinear parabolic equations and the global attractor A0for the homogenized equation is discussed, and an explicit error estimate between Aε and A0 is given.

  2. The homogenization of a class of degenerate quasilinear parabolic equations

    Institute of Scientific and Technical Information of China (English)

    ZHANG Xingyou; HUANG Yong

    2003-01-01

    The homogenization of a class of degenerate quasilinear parabolic equations is studied. The Ap weight theory and the classical compensated compactness method are incorporated to obtain the homogenized equation.

  3. IDENTIFICATION OF PARAMETERS IN PARABOLIC EQUATIONS WITH NONLINEARITY

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    In this paper, we consider the identification of parameters in parabolic equations with nonlinearity. Some approximation processes for the identification problem are given. Our results improve and generalize the previous results.

  4. Classification of conformal representations induced from the maximal cuspidal parabolic

    Energy Technology Data Exchange (ETDEWEB)

    Dobrev, V. K., E-mail: dobrev@inrne.bas.bg [Scuola Internazionale Superiore di Studi Avanzati (Italy)

    2017-03-15

    In the present paper we continue the project of systematic construction of invariant differential operators on the example of representations of the conformal algebra induced from the maximal cuspidal parabolic.

  5. Differentiability at lateral boundary for fully nonlinear parabolic equations

    Science.gov (United States)

    Ma, Feiyao; Moreira, Diego R.; Wang, Lihe

    2017-09-01

    For fully nonlinear uniformly parabolic equations, the first derivatives regularity of viscosity solutions at lateral boundary is studied under new Dini type conditions for the boundary, which is called Reifenberg Dini conditions and is weaker than usual Dini conditions.

  6. FASTRACK (TM): Parabolic and Suborbital Experiment Support Facility

    Science.gov (United States)

    Richards, Stephanie E. (Compiler); Levine, Howard G.; Romero, V.

    2016-01-01

    FASTRACK was developed by NASA Kennedy Space Center and Space Florida to provide capabilities to conduct frequent, affordable, and responsive flight opportunities for reduced gravity experiments, technology development, and hardware testing on suborbital vehicles and parabolic flights.

  7. Quasiconformal mappings and degenerate elliptic and parabolic equations

    Directory of Open Access Journals (Sweden)

    Filippo Chiarenza

    1987-11-01

    Full Text Available In this paper two Harnak inequalities are proved concerning a degenerate elliptic and a degenerate parabolic equation. In both cases the weight giving the degeneracy is a power of the jacobian of a quasiconformal mapping.

  8. Effect of iron-chelate treatments during imbibition on the concentration of minerals and phenolic compounds in three edible sprouts

    Science.gov (United States)

    Fe is an essential micronutrient involved in fundamental biological processes in humans, as well as in plants. In particular, Fe is known as a very important mineral due to its frequent deficiency in humans. The objectives of this study were to increase Fe concentration in three species of sprouts (...

  9. Thermal buffering of receivers for parabolic dish solar thermal power plants

    Science.gov (United States)

    Manvi, R.; Fujita, T.; Gajanana, B. C.; Marcus, C. J.

    1980-01-01

    A parabolic dish solar thermal power plant comprises a field of parabolic dish power modules where each module is composed of a two-axis tracking parabolic dish concentrator which reflects sunlight (insolation) into the aperture of a cavity receiver at the focal point of the dish. The heat generated by the solar flux entering the receiver is removed by a heat transfer fluid. In the dish power module, this heat is used to drive a small heat engine/generator assembly which is directly connected to the cavity receiver at the focal point. A computer analysis is performed to assess the thermal buffering characteristics of receivers containing sensible and latent heat thermal energy storage. Parametric variations of the thermal inertia of the integrated receiver-buffer storage systems coupled with different fluid flow rate control strategies are carried out to delineate the effect of buffer storage, the transient response of the receiver-storage systems and corresponding fluid outlet temperature. It is concluded that addition of phase change buffer storage will substantially improve system operational characteristics during periods of rapidly fluctuating insolation due to cloud passage.

  10. Thermal output analysis of a designed parabolic trough solar field for moderate temperature industrial load

    Directory of Open Access Journals (Sweden)

    Rizwan Masood

    2016-04-01

    Full Text Available This paper presents an overview of the Parabolic Trough Solar Collectors, which is a fastest growing technology amongst concentrated solar power technologies. It is largely being used in developed countries; mainly in steam power cycles for electricity generation but its use is not limited to electric power generation. This technology is also being used for many other applications like refrigeration and air-conditioning, desalination of sea water, pumping of irrigation water and many other heating applications for process industry. Though this technology is already being used in many developed countries but there is barely any development in Malaysia. There is thus need for assessment of this technology to explore the potential industrial applications, under local environmental conditions. In this article basic design and development considerations for a parabolic trough collector system have been discussed. This paper also includes a thermal output analysis of a designed parabolic trough solar field to provide the baseline information for industrial applications feasibility study. System Advisor Model (SAM has been used for this analysis, under environmental conditions of Ipoh, Malaysia. The results of simulation indicate that considerable amount of high temperature thermal energy can be obtained. The heat transfer fluid temperature reached up to 200 to 230oC, which can be used to operate an unfired boiler to produce steam or in some other industrial thermal application.

  11. 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.

  12. MAXIMUM PRINCIPLES FOR SECOND-ORDER PARABOLIC EQUATIONS

    Institute of Scientific and Technical Information of China (English)

    Antonio Vitolo

    2004-01-01

    This paper is the parabolic counterpart of previous ones about elliptic operators in unbounded domains. Maximum principles for second-order linear parabolic equations are established showing a variant of the ABP-Krylov-Tso estimate, based lower bound for super-solutions due to Krylov and Safonov. The results imply the uniqueness for the Cauchy-Dirichlet problem in a large class of infinite cylindrical and non-cylindrical domains.

  13. The parabolic trigonometric functions and the Chebyshev radicals

    OpenAIRE

    Dattoli, G.; Migliorati, M.; Ricci, P. E.

    2011-01-01

    The parabolic trigonometric functions have recently been introduced as an intermediate step between circular and hyperbolic functions. They have been shown to be expressible in terms of irrational functions, linked to the solution of third degree algebraic equations. We show the link of the parabolic trigonometric functions with the Chebyshev radicals and also prove that further generalized forms of trigonometric functions, providing the natural solutions of the quintic algebraic equation, ca...

  14. Comparison principle for parabolic equations in the Heisenberg group

    Directory of Open Access Journals (Sweden)

    Thomas Bieske

    2005-09-01

    Full Text Available We define two notions of viscosity solutions to parabolic equations in the Heisenberg group, depending on whether the test functions concern only the past or both the past and the future. We then exploit the Heisenberg geometry to prove a comparison principle for a class of parabolic equations and show the sufficiency of considering the test functions that concern only the past.

  15. Null controllability for a parabolic-elliptic coupled system

    CERN Document Server

    Fernández-Cara, E; de Menezes, S B

    2012-01-01

    In this paper, we prove the null controllability of some parabolic-elliptic systems. The control is distributed, locally supported in space and appears only in one PDE. The arguments rely on fixed-point reformulation and suitable Carleman estimates for the solutions to the adjoint system. Under appropriate assumptions, we also prove that the solution can be obtained as the asymptotic limit of some similar parabolic systems.

  16. Three-dimensional nonparaxial beams in parabolic rotational coordinates.

    Science.gov (United States)

    Deng, Dongmei; Gao, Yuanmei; Zhao, Juanying; Zhang, Peng; Chen, Zhigang

    2013-10-01

    We introduce a class of three-dimensional nonparaxial optical beams found in a parabolic rotational coordinate system. These beams, representing exact solutions of the nonparaxial Helmholtz equation, have inherent parabolic symmetries. Assisted with a computer-generated holography, we experimentally demonstrate the generation of different modes of these beams. The observed transverse beam patterns along the propagation direction agree well with those from our theoretical predication.

  17. Direct thermal desorption of semivolatile organic compounds from diffusion denuders and gas chromatographic analysis for trace concentration measurement.

    Energy Technology Data Exchange (ETDEWEB)

    Tobias, D. E.; Perlinger, J. A.; Morrow, P. S.; Doskey, P. V.; Perram, D.L.; Environmental Science Division; Michigan Technological Univ.

    2007-01-01

    A novel method for collection and analysis of vapor-phase semivolatile organic compounds (SOCs) in ambient air is presented. The method utilizes thermal desorption of SOCs trapped in diffusion denuders coupled with cryogenic preconcentration on Tenax-TA and analysis by high resolution gas chromatography (GC)-electron-capture detection (ECD). The sampling and analysis methods employ custom-fabricated multicapillary diffusion denuders, a hot gas spike (HGS) apparatus to load known quantities of thermally stable standards into diffusion denuders prior to sample collection, a custom-fabricated oven to thermally desorb SOCs from the diffusion denuder, and a programmable temperature vaporization (PTV) inlet containing a liner packed with Tenax-TA for effective preconcentration of the analytes and water management. High flow rates into the PTV inlet of 750 mL min-1during thermal desorption are ca. a factor of ten greater than typically used. To improve resolution and retention time stability, the thermal desorption and PTV inlet programming procedure includes three steps to prevent water from entering the analytic column while effectively transferring the analytes into the GC system. The instrumentation and procedures provide virtually complete and consistent transfer of analytes collected from ambient air into the GC evidenced by recovery of seven replicates of four internal standards of 90.7 {+-} 4.0-120 {+-} 23% (mean {+-} 95% confidence interval, CI). Retention time based compound identification is facilitated by low retention time variability with an average 95% CI of 0.024 min for sixteen replicates of eight standards. Procedure details and performance metrics as well as ambient sampling results are presented.

  18. Direct thermal desorption of semivolatile organic compounds from diffusion denuders and gas chromatographic analysis for trace concentration measurement.

    Science.gov (United States)

    Tobias, David E; Perlinger, Judith A; Morrow, Patrick S; Doskey, Paul V; Perram, David L

    2007-01-26

    A novel method for collection and analysis of vapor-phase semivolatile organic compounds (SOCs) in ambient air is presented. The method utilizes thermal desorption of SOCs trapped in diffusion denuders coupled with cryogenic preconcentration on Tenax-TA and analysis by high resolution gas chromatography (GC)-electron-capture detection (ECD). The sampling and analysis methods employ custom-fabricated multicapillary diffusion denuders, a hot gas spike (HGS) apparatus to load known quantities of thermally stable standards into diffusion denuders prior to sample collection, a custom-fabricated oven to thermally desorb SOCs from the diffusion denuder, and a programmable temperature vaporization (PTV) inlet containing a liner packed with Tenax-TA for effective preconcentration of the analytes and water management. High flow rates into the PTV inlet of 750mLmin(-1)during thermal desorption are ca. a factor of ten greater than typically used. To improve resolution and retention time stability, the thermal desorption and PTV inlet programming procedure includes three steps to prevent water from entering the analytic column while effectively transferring the analytes into the GC system. The instrumentation and procedures provide virtually complete and consistent transfer of analytes collected from ambient air into the GC evidenced by recovery of seven replicates of four internal standards of 90.7+/-4.0-120+/-23% (mean+/-95% confidence interval, CI). Retention time based compound identification is facilitated by low retention time variability with an average 95% CI of 0.024min for sixteen replicates of eight standards. Procedure details and performance metrics as well as ambient sampling results are presented.

  19. Fabrication and characterization of non-linear parabolic microporous membranes.

    Science.gov (United States)

    Rajasekaran, Pradeep Ramiah; Sharifi, Payam; Wolff, Justin; Kohli, Punit

    2015-01-01

    Large scale fabrication of non-linear microporous membranes is of technological importance in many applications ranging from separation to microfluidics. However, their fabrication using traditional techniques is limited in scope. We report on fabrication and characterization of non-linear parabolic micropores (PMS) in polymer membranes by utilizing flow properties of fluids. The shape of the fabricated PMS corroborated well with simplified Navier-Stokes equation describing parabolic relationship of the form L - t(1/2). Here, L is a measure of the diameter of the fabricated micropores during flow time (t). The surface of PMS is smooth due to fluid surface tension at fluid-air interface. We demonstrate fabrication of PMS using curable polydimethylsiloxane (PDMS). The parabolic shape of micropores was a result of interplay between horizontal and vertical fluid movements due to capillary, viscoelastic, and gravitational forces. We also demonstrate fabrication of asymmetric "off-centered PMS" and an array of PMS membranes using this simple fabrication technique. PMS containing membranes with nanoscale dimensions are also possible by controlling the experimental conditions. The present method provides a simple, easy to adopt, and energy efficient way for fabricating non-linear parabolic shape pores at microscale. The prepared parabolic membranes may find applications in many areas including separation, parabolic optics, micro-nozzles / -valves / -pumps, and microfluidic and microelectronic delivery systems.

  20. Indoor and outdoor concentrations of fine particles, particle-bound PAHs and volatile organic compounds in Kaunas, Lithuania.

    Science.gov (United States)

    Kliucininkas, Linas; Martuzevicius, Dainius; Krugly, Edvinas; Prasauskas, Tadas; Kauneliene, Violeta; Molnar, Peter; Strandberg, Bo

    2011-01-01

    This complex study presents indoor and outdoor levels of air-borne fine particles, particle-bound PAHs and VOCs at two urban locations in the city of Kaunas, Lithuania, and considers possible sources of pollution. Two sampling campaigns were performed in January-February and March-April 2009. The mean outdoor PM(2.5) concentration at Location 1 in winter was 34.5 ± 15.2 µg m(-3) while in spring it was 24.7 ± 12.2 µg m(-3); at Location 2 the corresponding values were 36.7 ± 21.7 and 22.4 ± 19.4 µg m(-3), respectively. In general there was little difference between the PM concentrations at Locations 1 and 2. PM(2.5) concentrations were lower during the spring sampling campaign. These PM concentrations were similar to those in many other European cities; however, the levels of most PAHs analysed were notably higher. The mean sum PAH concentrations at Locations 1 and 2 in the winter campaign were 75.1 ± 32.7 and 32.7 ± 11.8 ng m(-3), respectively. These differences are greater than expected from the difference in traffic intensity at the two sites, suggesting that there is another significant source of PAH emissions at Location 1 in addition to the traffic. The low observed indoor/outdoor (I/O) ratios indicate that PAH emissions at the locations studied arise primarily from outdoor sources. The buildings at both locations have old windows with wooden frames that are fairly permissive in terms of air circulation. VOC concentrations were mostly low and comparable to those reported from Sweden. The mean outdoor concentrations of VOC's were: 0.7 ± 0.2, 3.0 ± 0.8, 0.5 ± 0.2, 3.5 ± 0.3, and 0.2 ± 0.1 µg m(-3), for benzene, toluene, ethylbenzene, sum of m-, p-, o-xylenes, and naphthalene, respectively. Higher concentrations of VOCs were observed during the winter campaign, possibly due to slower dispersion, slower chemical transformations and/or the lengthy "cold start" period required by vehicles in the wintertime. A trajectory analysis showed that air masses

  1. 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.

  2. Toxicological assessment of concentrations of volatile organic compounds found in the ambient air of Seabrook, Texas and surrounding areas

    Science.gov (United States)

    Babin, Latrice Bundage

    Seabrook, Texas, a residential community located in the southeast fringes of Houston, Texas, the fourth largest metropolis in the United States, is adjacent to a major industrial complex of petrochemical plants, chemical plants, refineries, hazardous materials storage facilities, and the intertwining of pipelines. The close proximity of residential communities to industrial complexes and their emission sources creates concern of the potential adverse health effects that could be a result of long-term exposure to Hazardous Air Pollutants (HAPs) even at low concentration. The purpose of this study is to assess the potential adverse health affects of low-level exposure of benzene, styrene, and 1, 1-dichloroethene that residents may experience. The case study utilized the screening data performed in a previous study conducted by the TSU NASA URC Laboratory. The sample results were compared to Texas Commission on Environmental Quality (TCEQ) guideline standards known as Effects Screening Levels (ESLs) to determine whether the ambient concentration levels were aligned with the TCEQ's pre-determined health cut off values. Special interest in the probable affects on lung epithelial cells and hepatic cells by the inhalation of benzene, styrene and 1,1-dichloroethene was examined by low level exposure (0.100ppm to 4ppm) of these chemicals for 4- and 6-hour exposure periods to determine whether the cells metabolic activity is adversely affected. Cytotoxicity of test chemicals was investigated utilizing MTT [3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide] assay protocol. Validation of the presence of benzene, styrene and 1,1-dichloroethene was performed by incubating a known dilution of the respective chemical for 4- and 6-hours to determine the approximate remaining concentration that should remain in the test media after the given exposure in the 37° incubator. Results of the study show little difference in the viability of the cells at the concentrations

  3. Parabolic Trough Receiver Heat Loss Testing (Poster)

    Energy Technology Data Exchange (ETDEWEB)

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

    2007-03-01

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

  4. Affective states and adaptation to parabolic flights

    Science.gov (United States)

    Collado, Aurélie; Langlet, Cécile; Tzanova, Tzvetomira; Hainaut, Jean-Philippe; Monfort, Vincent; Bolmont, Benoît

    2017-05-01

    This exploratory study investigates (i) inter-individual variations of affective states before a parabolic flight (i.e., PF) on the basis of quality of adaptation to physical demands, and (ii) intra-individual variations of affective states during a PF. Mood-states, state-anxiety and salivary cortisol were assessed in two groups with a different quality of adaptation (an Adaptive Group, i.e., AG, and a Maladaptive Group, i.e., MG) before and during a PF. Before PF, MG scored higher on mood states (Anger-Hostility, Fatigue-Inertia) than AG. During the flight, while AG seemed to present ;normal; affective responses to the demanding environment (e.g., increase in salivary cortisol), MG presented increases in mood states such as Confusion-Bewilderment or Tension-Anxiety. The findings suggest that the psychological states of MG could have disturbed their ability to integrate sensory information from an unusual environment, which led to difficulties in coping with the physical demands of PF.

  5. The 1D parabolic-parabolic Patlak-Keller-Segel model of chemotaxis: The particular integrable case and soliton solution

    Science.gov (United States)

    Shubina, Maria

    2016-09-01

    In this paper, we investigate the one-dimensional parabolic-parabolic Patlak-Keller-Segel model of chemotaxis. For the case when the diffusion coefficient of chemical substance is equal to two, in terms of travelling wave variables the reduced system appears integrable and allows the analytical solution. We obtain the exact soliton solutions, one of which is exactly the one-soliton solution of the Korteweg-de Vries equation.

  6. Exploratory Metabolomic Analyses Reveal Compounds Correlated with Lutein Concentration in Frontal Cortex, Hippocampus, and Occipital Cortex of Human Infant Brain.

    Directory of Open Access Journals (Sweden)

    Jacqueline C Lieblein-Boff

    Full Text Available Lutein is a dietary carotenoid well known for its role as an antioxidant in the macula, and recent reports implicate a role for lutein in cognitive function. Lutein is the dominant carotenoid in both pediatric and geriatric brain tissue. In addition, cognitive function in older adults correlated with macular and postmortem brain lutein concentrations. Furthermore, lutein was found to preferentially accumulate in the infant brain in comparison to other carotenoids that are predominant in diet. While lutein is consistently related to cognitive function, the mechanisms by which lutein may influence cognition are not clear. In an effort to identify potential mechanisms through which lutein might influence neurodevelopment, an exploratory study relating metabolite signatures and lutein was completed. Post-mortem metabolomic analyses were performed on human infant brain tissues in three regions important for learning and memory: the frontal cortex, hippocampus, and occipital cortex. Metabolomic profiles were compared to lutein concentration, and correlations were identified and reported here. A total of 1276 correlations were carried out across all brain regions. Of 427 metabolites analyzed, 257 were metabolites of known identity. Unidentified metabolite correlations (510 were excluded. In addition, moderate correlations with xenobiotic relationships (2 or those driven by single outliers (3 were excluded from further study. Lutein concentrations correlated with lipid pathway metabolites, energy pathway metabolites, brain osmolytes, amino acid neurotransmitters, and the antioxidant homocarnosine. These correlations were often brain region-specific. Revealing relationships between lutein and metabolic pathways may help identify potential candidates on which to complete further analyses and may shed light on important roles of lutein in the human brain during development.

  7. Rotating disk sorbent extraction for pre-concentration of chromogenic organic compounds and direct determination by solid phase spectrophotometry.

    Science.gov (United States)

    Richter, Pablo; Cañas, Alejandro; Muñoz, Carlos; Leiva, Claudio; Ahumada, Inés

    2011-06-10

    A novel and very simple microextraction approach for pre-concentration and direct solid phase spectrophotometric measurement has been developed for the determination of chromogenic analytes. The model analyte to assess this approach was the chromophore malachite green (MG). The analyte was extracted from water samples onto a small rotating disk made of Teflon containing a sorbent phase of polydimethylsiloxane (PDMS) on one of its surfaces. We refer to the extraction procedure as rotating disk sorptive extraction (RDSE). After extraction, the sorbent phase with the concentrated analyte was separated from the Teflon disk and used directly for MG determination by solid phase spectrophotometry at 624 nm, without the necessity of a desorption step. Chemical and extraction variables such as concentration of sodium sulfate, pH, disk rotational velocity, extraction time, and temperature were studied in order to establish the best conditions for extraction. Under optimum conditions, the extraction of MG was carried out in 18 min and 90 min, for sample volumes of 100mL or 1000 mL, respectively. The detection limit, based on three times the standard deviation of the blank phase (3σ(b)), was 1.4 μg L⁻¹ and the repeatability, expressed as relative standard deviation (RSD), for 20 μg L⁻¹ MG was 8.1%. This study also applied the method to real samples, obtaining quantitative recovery (mean recovery of 99.3%). The PDMS phases could be reused after desorbing the MG into methanol for 3h. Replacement of the PDMS film onto the disk is very easy and low cost.

  8. Evaluation of the use of performance reference compounds in an Oasis-HLB adsorbent based passive sampler for improving water concentration estimates of polar herbicides in freshwater.

    Science.gov (United States)

    Mazzella, Nicolas; Lissalde, Sophie; Moreira, Sylvia; Delmas, François; Mazellier, Patrick; Huckins, James N

    2010-03-01

    Passive samplers such as the Polar Organic Chemical Integrative Sampler (POCIS) are useful tools for monitoring trace levels of polar organic chemicals in aquatic environments. The use of performance reference compounds (PRC) spiked into the POCIS adsorbent for in situ calibration may improve the semiquantitative nature of water concentration estimates based on this type of sampler. In this work, deuterium labeled atrazine-desisopropyl (DIA-d5) was chosen as PRC because of its relatively high fugacity from Oasis HLB (the POCIS adsorbent used) and our earlier evidence of its isotropic exchange. In situ calibration of POCIS spiked with DIA-d5 was performed, and the resulting time-weighted average concentration estimates were compared with similar values from an automatic sampler equipped with Oasis HLB cartridges. Before PRC correction, water concentration estimates based on POCIS data sampling rates from a laboratory calibration exposure were systematically lower than the reference concentrations obtained with the automatic sampler. Use of the DIA-d5 PRC data to correct POCIS sampling rates narrowed differences between corresponding values derived from the two methods. Application of PRCs for in situ calibration seems promising for improving POCIS-derived concentration estimates of polar pesticides. However, careful attention must be paid to the minimization of matrix effects when the quantification is performed by HPLC-ESI-MS/MS.

  9. Temperature dependence of the particle/gas partition coefficient: An application to predict indoor gas-phase concentrations of semi-volatile organic compounds.

    Science.gov (United States)

    Wei, Wenjuan; Mandin, Corinne; Blanchard, Olivier; Mercier, Fabien; Pelletier, Maud; Le Bot, Barbara; Glorennec, Philippe; Ramalho, Olivier

    2016-09-01

    The indoor gas-phase concentrations of semi-volatile organic compounds (SVOCs) can be predicted from their respective concentrations in airborne particles by applying the particle/gas partitioning equilibrium. The temperature used for partitioning is often set to 25°C. However, indoor temperatures frequently differ from this reference value. This assumption may result in errors in the predicted equilibrium gas-phase SVOC concentrations. To improve the prediction model, the temperature dependence of the particle/gas partition coefficient must be addressed. In this paper, a theoretical relationship between the particle/gas partition coefficient and temperature was developed based on the SVOC absorptive mechanism. The SVOC particle/gas partition coefficients predicted by employing the derived theoretical relationship agree well with the experimental data retrieved from the literature (R>0.93). The influence of temperature on the equilibrium gas-phase SVOC concentration was quantified by a dimensionless analysis of the derived relationship between the SVOC particle/gas partition coefficient and temperature. The predicted equilibrium gas-phase SVOC concentration decreased by between 31% and 53% when the temperature was lowered by 6°C, while it increased by up to 750% when the indoor temperature increased from 15°C to 30°C.

  10. Evaluation of the use of performance reference compounds in an oasis-HLB adsorbent based passive sampler for improving water concentration estimates of polar herbicides in freshwater

    Science.gov (United States)

    Mazzella, N.; Lissalde, S.; Moreira, S.; Delmas, F.; Mazellier, P.; Huckins, J.N.

    2010-01-01

    Passive samplers such as the Polar Organic Chemical Integrative Sampler (POCIS) are useful tools for monitoring trace levels of polar organic chemicals in aquatic environments. The use of performance reference compounds (PRC) spiked into the POCIS adsorbent for in situ calibration may improve the semiquantitative nature of water concentration estimates based on this type of sampler. In this work, deuterium labeled atrazine-desisopropyl (DIA-d5) was chosen as PRC because of its relatively high fugacity from Oasis HLB (the POCIS adsorbent used) and our earlier evidence of its isotropic exchange. In situ calibration of POCIS spiked with DIA-d5was performed, and the resulting time-weighted average concentration estimates were compared with similar values from an automatic sampler equipped with Oasis HLB cartridges. Before PRC correction, water concentration estimates based on POCIS data sampling ratesfrom a laboratory calibration exposure were systematically lower than the reference concentrations obtained with the automatic sampler. Use of the DIA-d5 PRC data to correct POCIS sampling rates narrowed differences between corresponding values derived from the two methods. Application of PRCs for in situ calibration seems promising for improving POCIS-derived concentration estimates of polar pesticides. However, careful attention must be paid to the minimization of matrix effects when the quantification is performed by HPLC-ESI-MS/MS. ?? 2010 American Chemical Society.

  11. Temperature dependence of the particle/gas partition coefficient: An application to predict indoor gas-phase concentrations of semi-volatile organic compounds

    Energy Technology Data Exchange (ETDEWEB)

    Wei, Wenjuan, E-mail: Wenjuan.Wei@cstb.fr [University of Paris-Est, Scientific and Technical Center for Building (CSTB), Health and Comfort Department, French Indoor Air Quality Observatory (OQAI), 84 Avenue Jean Jaurès, Champs sur Marne, 77447 Marne la Vallée Cedex 2 (France); Mandin, Corinne [University of Paris-Est, Scientific and Technical Center for Building (CSTB), Health and Comfort Department, French Indoor Air Quality Observatory (OQAI), 84 Avenue Jean Jaurès, Champs sur Marne, 77447 Marne la Vallée Cedex 2 (France); INSERM-U1085, Irset-Research Institute for Environmental and Occupational Health, Rennes (France); LERES-Environment and Health Research Laboratory (Irset and EHESP Technologic Platform), Rennes (France); Blanchard, Olivier [EHESP-School of Public Health, Sorbonne Paris Cité, Rennes (France); INSERM-U1085, Irset-Research Institute for Environmental and Occupational Health, Rennes (France); Mercier, Fabien [EHESP-School of Public Health, Sorbonne Paris Cité, Rennes (France); LERES-Environment and Health Research Laboratory (Irset and EHESP Technologic Platform), Rennes (France); INSERM-U1085, Irset-Research Institute for Environmental and Occupational Health, Rennes (France); Pelletier, Maud [EHESP-School of Public Health, Sorbonne Paris Cité, Rennes (France); INSERM-U1085, Irset-Research Institute for Environmental and Occupational Health, Rennes (France); Le Bot, Barbara [EHESP-School of Public Health, Sorbonne Paris Cité, Rennes (France); LERES-Environment and Health Research Laboratory (Irset and EHESP Technologic Platform), Rennes (France); INSERM-U1085, Irset-Research Institute for Environmental and Occupational Health, Rennes (France); and others

    2016-09-01

    The indoor gas-phase concentrations of semi-volatile organic compounds (SVOCs) can be predicted from their respective concentrations in airborne particles by applying the particle/gas partitioning equilibrium. The temperature used for partitioning is often set to 25 °C. However, indoor temperatures frequently differ from this reference value. This assumption may result in errors in the predicted equilibrium gas-phase SVOC concentrations. To improve the prediction model, the temperature dependence of the particle/gas partition coefficient must be addressed. In this paper, a theoretical relationship between the particle/gas partition coefficient and temperature was developed based on the SVOC absorptive mechanism. The SVOC particle/gas partition coefficients predicted by employing the derived theoretical relationship agree well with the experimental data retrieved from the literature (R > 0.93). The influence of temperature on the equilibrium gas-phase SVOC concentration was quantified by a dimensionless analysis of the derived relationship between the SVOC particle/gas partition coefficient and temperature. The predicted equilibrium gas-phase SVOC concentration decreased by between 31% and 53% when the temperature was lowered by 6 °C, while it increased by up to 750% when the indoor temperature increased from 15 °C to 30 °C. - Highlights: • A theoretical relationship between K{sub p} and temperature was developed. • The relationship was based on the SVOC absorptive mechanism. • The temperature impact was quantified by a dimensionless analysis.

  12. Experimental comparison of alternative convection suppression arrangements for concentrating integral collector storage solar water heaters

    Energy Technology Data Exchange (ETDEWEB)

    Smyth, M.; McGarrigle, P.; Eames, P.C. [Ulster Univ., School of the Built Environment, Newtownabbey, Northern Ireland (United Kingdom); Norton, B. [Dublin Inst. of Technology, Dublin (Ireland)

    2005-02-01

    An experimental investigation of an inverted absorber integrated collector storage solar water heater mounted in the tertiary cavity of a compound parabolic concentrator with a secondary cylindrical reflector has been performed under simulated solar conditions. The solar water heaters performance was determined with the aperture parallel to the simulator for a range of transparent baffles positioned at different locations within the collector cavity. Results indicate that glass baffles located at the upper portion of the exit aperture of the CPC can reduce thermal losses through convection suppression without significantly increasing optical losses. (Author)

  13. The Problem of Automation of Solar Concentrator Assembly and Adjustment

    Directory of Open Access Journals (Sweden)

    Ernst Kussul

    2011-09-01

    Full Text Available Recently we have proposed a low cost solar concentrator based on a large number of small flat mirrors that approximates parabolic surface needed for solar light concentration. In this work we describe an improvement of the concentrator support frame assembly. The improvement is connected with the design of the gauge/guages for support frame adjustment. The gauge has the parabolic edge and rotates in the central tube. Special nuts are moved up to the contact with parabolic edge of the gauge

  14. Molecularly imprinted polymers for the pre-concentration of polar organic micropollutants for compound-specific isotope analysis

    Science.gov (United States)

    Bakkour, Rani; Hofstetter, Thomas B.

    2014-05-01

    Compound-specific isotope analysis (CSIA) is a promising tool for assessing transformations of polar organic micropollutants such as pesticides, pharmaceuticals and consumer chemicals in aquatic systems. There are, however, two major challenges: (1) Polar organic micropollutants occur at very low levels and, as a consequence, large amounts of water are required to achieve analyte enrichment with factors of 50'000 and more, inevitably leading to large interferences from the aqueous matrix. (2) The polarity of these micropollutants impedes the use of typical non-polar sorbates for solid-phase enrichment. In view of these challenges, the use of molecularly imprinted polymers (MIP) is a promising approach to produce tailor-made materials for highly selective enrichment of polar organic micropollutants with reduced matrix interferences. In this work, we explore the use of MIP to selectively enrich benzotriazoles, an important class of polar aquatic micropollutants. Polymers were synthesized in the presence of 5,6-dimethyl-1H-benzotriazole as a template, which leaves cavities in the polymer matrix with a very high affinity to the template and closely related structures including our main target analyte, 1H-benzotrizole. After extraction of the template, specific recognition of substituted benzotriazoles is expected by the synthesized MIPs. As the MIP has no specific affinity to the matrix, there is also expected to be negligible enrichment of the matrix. Retention factors of the MIP are compared for different synthetic procedures and to non-imprinted polymers where no specific intermolecular interactions with benzotriazoles are expected. Optimum performance of the MIP is demonstrated in this study in terms of the selectivity of enrichment, recoveries of analytes and the goodness of carbon and nitrogen isotope ratios measured by gas chromatography isotopic ratio mass spectrometry (GC/IRMS). This approach will enable us to enrich large amounts of aqueous samples while

  15. The Transient Multidrug Resistance Phenotype of Salmonella enterica Swarming Cells Is Abolished by Sub-inhibitory Concentrations of Antimicrobial Compounds

    Directory of Open Access Journals (Sweden)

    Oihane Irazoki

    2017-07-01

    Full Text Available Swarming motility is the rapid and coordinated multicellular migration of bacteria across a moist surface. During swarming, bacterial cells exhibit increased resistance to multiple antibiotics, a phenomenon described as adaptive or transient resistance. In this study, we demonstrate that sub-inhibitory concentrations of cefotaxime, ciprofloxacin, trimethoprim, or chloramphenicol, but not that of amikacin, colistin, kanamycin or tetracycline, impair Salmonella enterica swarming. Chloramphenicol-treated S. enterica cells exhibited a clear decrease in their flagellar content, while treatment with other antibiotics that reduced swarming (cefotaxime, ciprofloxacin, and trimethoprim inhibited polar chemoreceptor array assembly. Moreover, the increased resistance phenotype acquired by swarming cells was abolished by the presence of these antimicrobials. The same occurred in cells treated with these antimicrobial agents in combination with others that had no effect on swarming motility. Our results reveal the potential of inhibiting swarming ability to enhance the therapeutic effectiveness of antimicrobial agents.

  16. Concentrations of persistent organochlorine compounds in human milk and placenta are higher in Denmark than in Finland

    DEFF Research Database (Denmark)

    Shen, H.; Main, K.M.; Andersson, A.M.

    2008-01-01

    in human milk samples from Finland (n = 65) and Denmark (n = 65) and in placentas from Finland (n = 112) and Denmark (n = 168). RESULTS: 1,1-dichloro-2,2-bis(4-chlorophenyl)ethane (p,p'-DDE) was the dominant pollutant. beta-Hexa-chloro-cyclohexane (beta-HCH), hexachlorobenzene (HCB), endosulfan-I, dieldrin......, oxychlordane (OXC), cis-heptachloroepoxide (c-HE) and 1,1,1-trichloro-2,2-bis(4-chlorophenyl)ethane (p,p'-DDT) were the other main organochlorines detected. Danish samples had significantly higher concentrations of p,p'-DDE, p,p'-DDT, beta-HCH, HCB, dieldrin, c-HE and OXC than did the Finnish samples. Levels...

  17. Cytotoxic effects of nanosilver are highly dependent on the chloride concentration and the presence of organic compounds in the cell culture media.

    Science.gov (United States)

    Kaiser, Jean-Pierre; Roesslein, Matthias; Diener, Liliane; Wichser, Adrian; Nowack, Bernd; Wick, Peter

    2017-01-06

    Nanosilver shows great promise for use in industrial, consumer or medical products because of its antimicrobial properties. However, the underlying mechanisms of the effects of silver nanoparticles on human cells are still controversial. Therefore, in the present study the influence of the chloride concentration and different serum content of culture media on the cytotoxic effects of nanosilver was systematically evaluated. Our results show that nanosilver toxicity was strongly affected by the composition of the culture media. The chloride concentration, as well as the carbon content affected the silver agglomeration and the complex formation. But also the dissolution of nanosilver and the availability of free silver ions (Ag(+)) were severely affected by the compositions of the culture media. Cells, only exposed to silver particles in suspension and dissolved silver complexes, did not show any effects under all conditions. Nanosilver agglomerates and silver complexes were not very soluble. Thus, cells growing on the bottom of the culture dishes were exposed to sedimented nanosilver agglomerates and precipitated silver complexes. Locally, the concentration of silver on the cell surface was very high, much higher compared the silver concentration in the bulk solution. The cytotoxic effects of nanosilver are therefore a combination of precipitated silver complexes and organic silver compounds rather than free silver ions. Silver coatings are used in health care products due to their bacteriostatic or antibacterial properties. The assessment of the toxicity of a certain compound is mostly done using in vitro assays. Therefore, cytotoxicity studies of nanosilver using human cell cultures have to be undertaken under well controlled and understood cultivations conditions in order to improve the compatibility of different studies. Especially when eukaryotic versus prokaryotic systems are compared for the evaluation of the use of nanosilver as antibacterial coatings for

  18. Pine Bark and Green Tea Concentrated Extracts: Antioxidant Activity and Comprehensive Characterization of Bioactive Compounds by HPLC–ESI-QTOF-MS

    Directory of Open Access Journals (Sweden)

    María de la Luz Cádiz-Gurrea

    2014-11-01

    Full Text Available The consumption of polyphenols has frequently been associated with low incidence of degenerative diseases. Most of these natural antioxidants come from fruits, vegetables, spices, grains and herbs. For this reason, there has been increasing interest in identifying plant extract compounds. Polymeric tannins and monomeric flavonoids, such as catechin and epicatechin, in pine bark and green tea extracts could be responsible for the higher antioxidant activities of these extracts. The aim of the present study was to characterize the phenolic compounds in pine bark and green tea concentrated extracts using high-performance liquid chromatography coupled to electrospray ionization mass spectrometry (HPLC–ESI-QTOF-MS. A total of 37 and 35 compounds from pine bark and green tea extracts, respectively, were identified as belonging to various structural classes, mainly flavan-3-ol and its derivatives (including procyanidins. The antioxidant capacity of both extracts was evaluated by three complementary antioxidant activity methods: Trolox equivalent antioxidant capacity (TEAC, ferric reducing antioxidant power (FRAP and oxygen radical absorbance capacity (ORAC. Higher antioxidant activity values by each method were obtained. In addition, total polyphenol and flavan-3-ol contents, which were determined by Folin–Ciocalteu and vanillin assays, respectively, exhibited higher amounts of gallic acid and (+-catechin equivalents.

  19. Effects of UV-B Radiation Levels on Concentrations of Phytosterols, Ergothioneine, and Polyphenolic Compounds in Mushroom Powders Used As Dietary Supplements.

    Science.gov (United States)

    Sapozhnikova, Yelena; Byrdwell, William Craig; Lobato, Amada; Romig, Bill

    2014-03-27

    Compositional changes of powder dietary supplements made from mushrooms exposed to different levels of UV-B irradiation were evaluated for the bioactive naturally occurring mushroom antioxidant, ergothioneine; other natural polyphenolic compounds, e.g., flavonoids, lignans, etc.; and selected phytosterols. Four types of mushroom powder consisting of white, brown (Agaricus bisporus), oyster (Pleurotus ostreatus), and shiitake (Lentinula edodes) mushrooms from three different treatment groups (control, low and high UV-B exposures) were evaluated. Ergothioneine concentrations found in mushroom powders were 0.4-10.4 mg/g dry weight (dw) and were not appreciably affected by UV-B radiation. No individual polyphenols were detected above 0.1 μg/g. Phytosterols ergosterol (2.4-6.2 mg/g dw) and campesterol (14-43 μg/g dw) were measured in mushroom powder samples. Ergosterol concentrations decreased significantly with the increased level of UV-B treatment for all mushroom powder types, except for white. These results provide some new information on effects of UV-B radiation on these important natural bioactive compounds in mushrooms.

  20. Parabolic trough Project in Cerro Prieto, Mexico

    Energy Technology Data Exchange (ETDEWEB)

    Lentz, A.; Cadenas, R.; Almanza, R.; Martinez, I.; Ruiz, V.

    2006-07-01

    Federal Electricity Commission (CFE), the most important electricity Company in Mexico wants to install a parabolic trough row in the Cerro Prieto Geothermal field. Cerro Prieto (CP) is the most important geothermal field in Mexico; this area has the highest levels of irradiance in the country. The levels of irradiance make it feasible to set up a solar collector field in the geothermal field to build a hybrid system in order to increase the steam and electricity production. There are several alternative in the hybrid system, depending where the solar field place is located. Two new options are presented in this paper. The first one uses water from the condenser in DSG with the solar field and steam is separated in the first separator. The second option (DSG), the steam produced is separated in an expansion vessel; the water is reinjected in the solar field and the steam goes to the turbine. This project plans to install an experimental facility to research and learning about the technology, CFE main objective will be the electricity generation; using steam from solar collectors using the existing turbines in CPIV; the second objective is to instruct the workers in the operation of the real facility. The third objective is to study the geothermal flow in the absorbers in Direct Steam Generation (DSG), which has salt and silica dissolved, and look for a possible solution for steam generation. The geothermal facilities have considerable experience using the brine flow, so it is not considered an impediment in the solar-geothermal hybrid system. (Author)

  1. Slope Error Measurements of Parabolic troughs using the Reflected Image of the Absorber Tube

    Energy Technology Data Exchange (ETDEWEB)

    Ulmer, S.; Heinz, B.; Pottler, K.; Lupfer, E.

    2006-07-01

    A new fast method for optically measuring the reflector slope of parabolic troughs with high accuracy has been developed. It uses the reflection of the absorber tube in the concentrator as seen from some distance and is therefore called absorber reflection method. A digital camera is placed at a distant observation point perpendicular to the trough axis with the concentrator orientated towards it. Then, a set of pictures from the absorber tube reflection is taken with the concentrator in slightly different tilt angles. A specially developed image analysis algorithm detects the edges of the absorber tube in the reflected images. This information, along with the geometric relationship between the components of the set-up and the known approximately parabolic shape of the concentrator, is used to calculate the slopes perpendicular to the trough axis. Measurement results of a EuroTrough segment of four facets are presented and verified with results from a reference measurement using high-resolution close-range photogrammetry. The results show good agreement as well in statistical values as in local values of the reflector slope. In contrast to the photogrammetric data acquisition method, the new technique allows for drastically reduced measurement time. (Author)

  2. Experimental Verification and Analysis of Solar Parabolic Collector for Water Distillation

    Directory of Open Access Journals (Sweden)

    Mr. Mohd. Rizwan

    2014-01-01

    Full Text Available The paper is concerned with an experimental study of parabolic trough collector with its sun tracking system designed and manufactured to facilitate rapid diffusion and widespread use of solar energy. The paper focuses on use of alternative source of energy (through suns radiation which is easy to install, operate and maintain. Also, to improve the performance of solar concentrator, different geometries were evaluated with respect to their optical and energy conversion efficiency. To assure good performance and long technical lifetime of a concentrating system, the solar reflectance of the reflectors must be high and long term stable. During the research carried out, focus had been shifted from evaluation of the performance of concentrating solar collector to analysis of the optical properties of reflector and absorbing materials. The shift of focus was motivated by the need to assess long term system performance and possibilities of optimizing the optical efficiency or reducing costs by using new types of reflector materials and absorbing materials. The Solar Parabolic Trough Collector (SPTC was fabricated in local workshops and the sun tracking system was assembled using electric and electronic components in the market, while the mechanical components making up the driving system were procured from the local market. The objective of the research is to obtain distilled water by heating it to a higher temperature by solar parabolic trough collector. Solar distillation is used to produce potable water or to produce water for lead acid batteries or in chemical laboratories as in this case. The level of dissolved solids in solar distilled water is less than 3 ppm and bacteria free. The requirements for this specific design are a target for distilling water regularly with low maintenance.

  3. Development of a system to evaluate compound identity, purity, and concentration in a single experiment and its application in quality assessment of combinatorial libraries and screening hits.

    Science.gov (United States)

    Yurek, David A; Branch, Derek L; Kuo, Ming-Shang

    2002-01-01

    The development and use of a new assay system for the simultaneous determination of identity, purity, and concentration of sample components from combinatorial libraries produced by parallel synthesis are described. The system makes use of high-performance liquid chromatography with UV/vis photodiode array (PDA), evaporative light scattering (ELSD), chemiluminescent nitrogen (CLND), and time-of-flight mass spectrometer (TOFMS) detectors (HPLC-PDA-ELSD-CLND-TOFMS). Although these detectors have previously been utilized separately for the analysis of combinatorial chemistry libraries, the use of TOFMS along with CLND provides a synergistic combination enabling target and side-product structures to be identified and their concentrations and purities determined in a single experiment from a solution containing microgram levels of material. The CLND was found to give a linear response based on the number of moles of nitrogen present. Therefore, if the number of nitrogens per molecule is known, the concentration of each nitrogen-containing sample component may be determined utilizing an unrelated co-injected standard. A molecular formula for an impurity may often be calculated from the exact mass determined by the TOFMS and knowledge of the chemistry involved. Thus, if the sample components contain nitrogen, the concentration of every identified HPLC peak may be determined even in the absence of primary standards. This combination of detectors enabled the characterization of both target compounds and byproducts in combinatorial libraries, allowing the optimization of library synthetic procedures. This system was also used to survey the quality of libraries, enabling the selection of the best libraries for screening. This method also facilitated the characterization of samples from combinatorial libraries found as hits in high-throughput screening to establish the potency of the leads based on their actual concentration. In addition, concentrations and potencies of

  4. Linear parabolic single-crystal diamond refractive lenses for synchrotron X-ray sources.

    Science.gov (United States)

    Terentyev, Sergey; Polikarpov, Maxim; Snigireva, Irina; Di Michiel, Marco; Zholudev, Sergey; Yunkin, Vyacheslav; Kuznetsov, Sergey; Blank, Vladimir; Snigirev, Anatoly

    2017-01-01

    Linear parabolic diamond refractive lenses are presented, designed to withstand high thermal and radiation loads coming from upgraded accelerator X-ray sources. Lenses were manufactured by picosecond laser treatment of a high-quality single-crystal synthetic diamond. Twelve lenses with radius of curvature at parabola apex R = 200 µm, geometrical aperture A = 900 µm and length L = 1.5 mm were stacked as a compound refractive lens and tested at the ESRF ID06 beamline. A focal spot of size 2.2 µm and a gain of 20 were measured at 8 keV. The lens profile and surface quality were estimated by grating interferometry and X-ray radiography. In addition, the influence of X-ray glitches on the focusing properties of the compound refractive lens were studied.

  5. 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)

  6. A Contribution for the Construction of Parabolic Mirrors

    CERN Document Server

    de Paula, L A N; Assis, A K T

    2008-01-01

    We present a new procedure for the construction of parabolic mirrors using low cost materials. We build a spinning system composed of nylon threads, fish hooks and a plastic bucket. We pour liquid plaster into the bucket and set it in constant rotational motion relative to the earth. A liquid substance assumes a parabolic profile when spinning at constant angular velocity relative to an inertial frame under the influence of an uniform vertical gravitational field. By keeping the bucket under rotation for a long time, the plaster solidifies into a parabolic format. We utilize this solidified plaster paraboloid as a model to construct a counter-mould of glass fibre and resin. Over this counter-mould it is placed stretched laminated foil and then it is poured thick plaster over it. In this way it is obtained a parabolic mirror made of laminated foil and plaster. Our only objective here is to present a new method for the construction of parabolic mirror using low cost materials. This allows further exploration of...

  7. A design method for closed loop solar energy systems with concentrating collectors

    Science.gov (United States)

    Ryan, W. A.

    1982-01-01

    A method of performance prediction and design for closed loop concentrating solar collector systems is presented, along with a comparison of prediction with results using a compound parabolic concentrating collector. The numerical model is an extension of Collares-Pereira and Rabl (1978) model for concentrating collectors to a closed-loop scenario, using a monthly average utilizability factor and the f-chart technique. The predictions were compared with simulations using the TRNSYS program, considering 1.5, 3.0, and 5.0 concentration factors, and a sensible heat storage system. Performance predictions were found to depart from the simulations by an average of 14.04% for all cases, with the predictions giving consistently lower results. The method is concluded to be useful for optimizing collector areas and concentration ratios in closed-loop systems.

  8. Concentrations of selected trace inorganic constituents and synthetic organic compounds in the water-table aquifers in the Memphis area, Tennessee

    Science.gov (United States)

    McMaster, B.W.; Parks, William Scott

    1988-01-01

    Water quality samples for analysis of selected trace inorganic constituents and synthetic organic compounds were collected from 29 private or observation wells in alluvium and fluvial deposits of Quaternary and Tertiary Age. The alluvium and fluvial deposits are the water table aquifers in the Memphis area. In addition, nine wells were installed in Memphis Light, Gas and Water Division well fields so that samples could be collected and analyzed to characterize the quality of water in the fluvial deposits at these well fields. Samples from seven of these wells (two were dry) were analyzed for major constituents and properties of water as well as for selected trace inorganic constituents and synthetic organic compounds. Analyses of the water from most of the 36 wells sampled indicated ranges in concentration values for the trace inorganic constituents that agreed with those previously known, although some new maximum values were established. The analysis of water from four wells indicated that the water is or may be contaminated. Concentrations of barium (1,400 micrograms/L -- ug/L), strontium (1,100 ug/L), and arsenic (15 ug/L), along with specific conductance (1,420 microsiemens/centimeter--us/cm) were in water from one well in the alluvium. Low concentrations (0.02 to 0.04 ug/L) of the pesticides aldrin, DDT, endosulfan, and perthane were present in water from two wells in the fluvial deposits. Water from one of these wells also contained 1,1,1 trichloroethane (4.4 ug/L). Analysis of water from another well in the fluvial deposits indicated values for specific conductance (1,100 uS/cm), alkalinity (508 milligrams per liter -- mg/L -- as CaCO3), hardness (550 mg/L as CaCO3), chloride (65 mg/L), and barium (240 ug/L) that are high for water from the fluvial deposits. (USGS)

  9. Gene Expression Response of Salmonella enterica Serotype Enteritidis Phage Type 8 to Subinhibitory Concentrations of the Plant-Derived Compounds Trans-Cinnamaldehyde and Eugenol

    Directory of Open Access Journals (Sweden)

    Anup Kollanoor Johny

    2017-09-01

    Full Text Available Background:Salmonella Enteritidis phage type 8 (PT8 is a major poultry-associated Salmonella strain implicated in foodborne outbreaks in the United States. We previously reported that two plant-derived compounds generally recognized as safe (GRAS, trans-cinnamaldehyde (TC, and eugenol (EG, significantly reduced S. Enteritidis colonization in broiler and layer chickens. To elucidate potential PT8 genes affected by TC and EG during colonization, a whole-genome microarray analysis of the bacterium treated with TC and EG was conducted.Results:S. Enteritidis PT8 was grown in Luria-Bertani broth at 37°C to an OD600 of ~0.5. Subinhibitory concentrations (SICs; concentration that does not inhibit bacterial growth of TC (0.01%; 0.75 mM or EG (0.04%; 2.46 mM were then added to the culture. S. Enteritidis PT8 RNA was extracted before and 30 min after TC or EG addition. Labeled cDNA from three replicate experiments was subsequently hybridized to a microarray of over 99% of S. Enteritidis PT4 genes, and the hybridization signals were quantified. The plant-derived compounds down-regulated (P < 0.005 expression of S. Enteritidis PT8 genes involved in flagellar motility, regulation of the Salmonella Pathogenicity Island 1, and invasion of intestinal epithelial cells. TC and EG also suppressed transcription of genes encoding multiple transport systems and outer membrane proteins. Moreover, several metabolic and biosynthetic pathways in the pathogen were down-regulated during exposure to the plant-derived compounds. Both TC and EG stimulated the transcription of heat shock genes, such as dnaK, dnaJ, ibpB, and ibpA in S. Enteritidis PT8 (P < 0.005. The results obtained from microarray were validated using a quantitative real-time PCR.Conclusion: The plant-derived compounds TC and EG exert antimicrobial effects on S. Enteritidis PT8 by affecting multiple genes, including those associated with virulence, colonization, cell membrane composition, and transport

  10. Accelerated parabolic Radon domain 2D adaptive multiple subtraction with fast iterative shrinkage thresholding algorithm and its application in parabolic Radon domain hybrid demultiple method

    Science.gov (United States)

    Li, Zhong-xiao; Li, Zhen-chun

    2017-08-01

    Adaptive multiple subtraction is an important step for successfully conducting surface-related multiple elimination in marine seismic exploration. 2D adaptive multiple subtraction conducted in the parabolic Radon domain has been proposed to better separate primaries and multiples than 2D adaptive multiple subtraction conducted in the time-offset domain. Additionally, the parabolic Radon domain hybrid demultiple method combining parabolic Radon filtering and parabolic Radon domain 2D adaptive multiple subtraction can better remove multiples than the cascaded demultiple method using time-offset domain 2D adaptive multiple subtraction and the parabolic Radon transform method sequentially. To solve the matching filter in the optimization problem with L1 norm minimization constraint of primaries, traditional parabolic Radon domain 2D adaptive multiple subtraction uses the iterative reweighted least squares (IRLS) algorithm, which is computationally expensive for solving a weighted LS inversion in each iteration. In this paper we introduce the fast iterative shrinkage thresholding algorithm (FISTA) as a faster alternative to the IRLS algorithm for parabolic Radon domain 2D adaptive multiple subtraction. FISTA uses the shrinkage-thresholding operator to promote the sparsity of estimated primaries and solves the 2D matching filter with iterative steps. FISTA based parabolic Radon domain 2D adaptive multiple subtraction reduces the computation time effectively while achieving similar accuracy compared with IRLS based parabolic Radon domain 2D adaptive multiple subtraction. Additionally, the provided examples show that FISTA based parabolic Radon domain 2D adaptive multiple subtraction can better separate primaries and multiples than FISTA based time-offset domain 2D adaptive multiple subtraction. Furthermore, we introduce FISTA based parabolic Radon domain 2D adaptive multiple subtraction into the parabolic Radon domain hybrid demultiple method to improve its computation

  11. 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.

  12. Design and Fabrication of a Two Axis Parabolic Solar Dish Collector

    Directory of Open Access Journals (Sweden)

    Prof. Sonal C Yogi

    2014-11-01

    Full Text Available The work consists of the design of the chain drive system and the fabrication of the two axis parabolic solar dish. It is a model study of the two axis parabolic dish which worked by the automatic circuit that was developed. Ready made parabolic solar dish is taken and fabricated. The circular iron ring provides the two axis motion of the dish. A compound chain drive system was developed for the smooth movement of the dish. An electromechanical system which tracks the sun on both axes and which is controlled via a programmable logic control (PLC was designed and implemented. In this a theoretical study was done. A C program was made which gave the required result for the graphical representation of the recorded radiation. Programmable Logic Controls (PLC was used instead of photo sensors, which are widely used for tracking the sun. The azimuthal angle of the sun from sunrise to sunset times was calculated for each day of the year at 23.59 Lat & 72.38Longitude in the Northern hemisphere, the location of the city Mehsana. According to this azimuth angle, the required analog signal was taken from the PLC analog module and sent to the power window motor, which controlled the position of the panel to ensure that the rays fall vertically on the panel. After the mechanical control of the system was started, the performance measurements of the solar panel were carried out. The values obtained from the measurements were compared and the necessary evaluations were conducted.

  13. Twelve-year trends in ambient concentrations of volatile organic compounds in a community of the Alberta Oil Sands Region, Canada.

    Science.gov (United States)

    Bari, Md Aynul; Kindzierski, Warren B; Spink, David

    2016-05-01

    Environmental exposure to volatile organic compounds (VOCs) in ambient air is one of a number of concerns that the First Nation Community of Fort McKay, Alberta has related to development of Canada's oil sands. An in-depth investigation of trends in ambient air VOC levels in Fort McKay was undertaken to better understand the role and possible significance of emissions from Alberta's oil sands development. A non-parametric trend detection method was used to investigate trends in emissions and ambient VOC concentrations over a 12-year (2001-2012) period. Relationships between ambient VOC concentrations and production indicators of oil sands operations around Fort McKay were also examined. A weak upward trend (significant at 90% confidence level) was found for ambient concentrations of total VOCs based on sixteen detected species with an annual increase of 0.64μg/m(3) (7.2%) per year (7.7μg/m(3) increase per decade). Indicators of production (i.e., annual bitumen production and mined oil sands quantities) were correlated with ambient total VOC concentrations. Only one of 29 VOC species evaluated (1-butene) showed a statistically significant upward trend (p=0.05). Observed geometric (arithmetic) mean and maximum ambient concentrations of selected VOCs of public health concern for most recent three years of the study period (2010-2012) were below chronic and acute health risk screening criteria of the U.S. Agency for Toxic Substances and Disease Registry and U.S. Environmental Protection Agency. Thirty-two VOCs are recommended for tracking in future air quality investigations in the community to better understand whether changes are occurring over time in relation to oil sands development activities and to inform policy makers about whether or not these changes warrant additional attention.

  14. Highly efficient end-side-pumped Nd:YAG solar laser by a heliostat-parabolic mirror system.

    Science.gov (United States)

    Almeida, J; Liang, D; Vistas, C R; Guillot, E

    2015-03-10

    We report a large improvement in the collection and slope efficiency of an Nd:YAG solar laser pumped by a heliostat-parabolic mirror system. A conical fused silica lens was used to further concentrate the solar radiation from the focal zone of a 2 m diameter primary concentrator to a Nd:YAG single-crystal rod within a conical pump cavity, which enabled multipass pumping to the active medium. A 56 W cw laser power was measured, corresponding to 21.1  W/m2 record-high solar laser collection efficiency with the heliostat-parabolic mirror system. 4.9% slope efficiency was calculated, corresponding to 175% enhancement over our previous result.

  15. Internal jugular pressure increases during parabolic flight.

    Science.gov (United States)

    Martin, David S; Lee, Stuart M C; Matz, Timothy P; Westby, Christian M; Scott, Jessica M; Stenger, Michael B; Platts, Steven H

    2016-12-01

    One hypothesized contributor to vision changes experienced by >75% of International Space Station astronauts is elevated intracranial pressure (ICP). While no definitive data yet exist, elevated ICP might be secondary to the microgravity-induced cephalad fluid shift, resulting in venous congestion (overfilling and distension) and inhibition of cerebrospinal and lymphatic fluid drainage from the skull. The objective of this study was to measure internal jugular venous pressure (IJVP) during normo- and hypo-gravity as an index of venous congestion. IJVP was measured noninvasively using compression sonography at rest during end-expiration in 11 normal, healthy subjects (3 M, 8 F) during normal gravity (1G; supine) and weightlessness (0G; seated) produced by parabolic flight. IJVP also was measured in two subjects during parabolas approximating Lunar (1/6G) and Martian gravity (1/3G). Finally, IJVP was measured during increased intrathoracic pressure produced using controlled Valsalva maneuvers. IJVP was higher in 0G than 1G (23.9 ± 5.6 vs. 9.9 ± 5.1 mmHg, mean ± SD P < 0.001) in all subjects, and IJVP increased as gravity levels decreased in two subjects. Finally, IJVP was greater in 0G than 1G at all expiration pressures (P < 0.01). Taken together, these data suggest that IJVP is elevated during acute exposure to reduced gravity and may be elevated further by conditions that increase intrathoracic pressure, a strong modulator of central venous pressure and IJVP However, whether elevated IJVP, and perhaps consequent venous congestion, observed during acute microgravity exposure contribute to vision changes during long-duration spaceflight is yet to be determined. Published 2016. This article is a U.S. Government work and is in the public domain in the USA. Physiological Reports published by Wiley Periodicals, Inc. on behalf of The Physiological Society and the American Physiological Society.

  16. CSP parabolic trough and power tower performance analysis through the Southern African universities radiometric network (SAURAN) data

    Science.gov (United States)

    Pidaparthi, A. S.; Dall, E. P.; Hoffmann, J. E.; Dinter, F.

    2016-05-01

    The objective of this paper is to analyse the performance of parabolic trough and power tower technologies by selecting two radiometric stations in different geographic locations, with approximately equal annual direct normal irradiance (DNI) values, but with different monthly DNI distributions. The two stations chosen for this study are situated at the University of Free State, Bloemfontein, Free State Province and in Vanrhynsdorp, Western Cape Province. The annual measured DNI values for both these locations in South Africa are in the range of 2500-2700 kWh/m2. The comparison between the different monthly DNI distributions of these selected sites includes an assessment of annual hourly data in order to study the performance analysis of the most mature concentrating solar power (CSP) technologies, namely parabolic trough and power tower plants. The weather data has been obtained from the Southern African Universities Radiometric Network (SAURAN). A comparison between the different monthly DNI distributions of these selected sites includes the assessment of hourly data. Selection of these radiometric stations has also been done on the basis that they have been operational for at least one year. The first year that most SAURAN stations have been online for at least one year is 2014, thus data from this year has been considered. The annual performance analysis shows that parabolic trough plants have a higher energy yield in Vanrhynsdorp while power tower plants seem to be more suitable for Bloemfontein. Power tower plants in both the locations have a higher annual energy yield when compared with parabolic trough plants. A parabolic trough power plant in Vanrhynsdorp in the Western Cape Province has very low monthly electricity generation in the winter months of May, June, July and August. This is partly due to the higher cosine losses in the parabolic trough `one-axis' tracking systems and lower DNI values in the winter months. However, a power tower plant in

  17. Molten salt parabolic trough system with synthetic oil preheating

    Science.gov (United States)

    Yuasa, Minoru; Hino, Koichi

    2017-06-01

    Molten salt parabolic trough system (MSPT), which can heat the heat transfer fluid (HTF) to 550 °C has a better performance than a synthetic oil parabolic trough system (SOPT), which can heat the HTF to 400 °C or less. The utilization of HTF at higher temperature in the parabolic trough system is able to realize the design of a smaller size of storage tank and higher heat to electricity conversion efficiency. However, with MSPT there is a great amount of heat loss at night so it is necessary to circulate the HTF at a high temperature of about 290 °C in order to prevent solidification. A new MSPT concept with SOPT preheating (MSSOPT) has been developed to reduce the heat loss at night. In this paper, the MSSOPT system, its performance by steady state analysis and annual performance analysis are introduced.

  18. 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.

  19. Decomposition method for solving parabolic equations in finite domains

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    This paper presents a comparison among Adomian decomposition method (ADM), Wavelet-Galerkin method (WGM),the fully explicit (1,7) finite difference technique (FTCS), the fully implicit (7,1) finite difference method (BTCS), (7,7)Crank-Nicholson type finite difference formula (C-N), the fully explicit method (1,13) and 9-point finite difference method, for solving parabolic differential equations with arbitrary boundary conditions and based on weak form functionals in finite domains.The problem is solved rapidly, easily and elegantly by ADM. The numerical results on a 2D transient heat conducting problem and 3D diffusion problem are used to validate the proposed ADM as an effective numerical method for solving finite domain parabolic equations. The numerical results showed that our present method is less time consuming and is easier to use than other methods. In addition, we prove the convergence of this method when it is applied to the nonlinear parabolic equation.

  20. Graphene Nanoribbon Conductance Model in Parabolic Band Structure

    Directory of Open Access Journals (Sweden)

    Mohammad Taghi Ahmadi

    2010-01-01

    Full Text Available Many experimental measurements have been done on GNR conductance. In this paper, analytical model of GNR conductance is presented. Moreover, comparison with published data which illustrates good agreement between them is studied. Conductance of GNR as a one-dimensional device channel with parabolic band structures near the charge neutrality point is improved. Based on quantum confinement effect, the conductance of GNR in parabolic part of the band structure, also the temperature-dependent conductance which displays minimum conductance near the charge neutrality point are calculated. Graphene nanoribbon (GNR with parabolic band structure near the minimum band energy terminates Fermi-Dirac integral base method on band structure study. While band structure is parabola, semiconducting GNRs conductance is a function of Fermi-Dirac integral which is based on Maxwell approximation in nondegenerate limit especially for a long channel.

  1. 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

    2017-02-01

    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.

  2. In-plane elastic stability of fixed parabolic shallow arches

    Institute of Scientific and Technical Information of China (English)

    CAI JianGuo; FENG Jian; CHEN Yao; HUANG LiFeng

    2009-01-01

    The nonlinear behavior of fixed parabolic shallow arches subjected to a vertical uniform load is inves-tigated to evaluate the in-plane buckling load. The virtual work principle method is used to establish the non-linear equilibrium and buckling equations. Analytical solutions for the non-linear in-plane sym-metric snap-through and antisymmetric bifurcation buckling loads are obtained. Based on the least square method, an approximation for the symmetric buckling load of fixed parabolic arch is proposedto simplify the solution process. And the relation between modified slenderness and buckling modes are discussed. Comparisons with the results of finite element analysis demonstrate that the solutions are accurate. A cable-arch structure is presented to improve the in-plane stability of parabolic arches. The comparison of buckling loads between cable-arch systems and arches only show that the effect of cables becomes more evident with the increase of arch's modified slenderness.

  3. In-plane elastic stability of fixed parabolic shallow arches

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    The nonlinear behavior of fixed parabolic shallow arches subjected to a vertical uniform load is inves- tigated to evaluate the in-plane buckling load. The virtual work principle method is used to establish the non-linear equilibrium and buckling equations. Analytical solutions for the non-linear in-plane sym- metric snap-through and antisymmetric bifurcation buckling loads are obtained. Based on the least square method, an approximation for the symmetric buckling load of fixed parabolic arch is proposed to simplify the solution process. And the relation between modified slenderness and buckling modes are discussed. Comparisons with the results of finite element analysis demonstrate that the solutions are accurate. A cable-arch structure is presented to improve the in-plane stability of parabolic arches. The comparison of buckling loads between cable-arch systems and arches only show that the effect of cables becomes more evident with the increase of arch’s modified slenderness.

  4. Analysis and conceptual design of a lunar radiator parabolic shade

    Science.gov (United States)

    Ewert, Michael K.; Clark, Craig S.

    1991-01-01

    On the moon, the available heat sink temperature for a vertical unshaded radiator at the equator is 322 K. A method of reducing this heat sink temperature using a parabolic trough shading device was investigated. A steady state heat balance was performed to predict the available heat sink temperature. The effect of optical surface properties on system performance was investigated. Various geometric configurations were also evaluated. A flexible shade conceptual design is presented which greatly reduces the weight and stowed volume of the system. The concept makes use of the natural catenary shape assumed by a flexible material when supported at two points. The catenary shape is very near parabolic. The lunar radiator parabolic shade design presented integrates the energy collection and rejection of a solar dynamic power cycle with the moderate temperature waste heat rejection of a lunar habitat.

  5. 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.

  6. Real Parabolic Vector Bundles over a Real Curve

    Indian Academy of Sciences (India)

    Sanjay Amrutiya

    2014-02-01

    We define real parabolic structures on real vector bundles over a real curve. Let $(X, _X)$ be a real curve, and let $S\\subset X$ be a non-empty finite subset of such that $_X(S) = S$. Let ≥ 2 be an integer. We construct an -fold cyclic cover : $Y→ X$ in the category of real curves, ramified precisely over each point of , and with the property that for any element of the Galois group , and any $y\\in Y$, one has $_Y(gy) = g^{-1}_Y(y)$. We established an equivalence between the category of real parabolic vector bundles on $(X,_X)$ with real parabolic structure over , all of whose weights are integral multiples of 1/, and the category of real -equivariant vector bundles on $(Y, _Y)$.

  7. Occurrence and concentrations of selected trace elements and halogenated organic compounds in stream sediments and potential sources of polychlorinated biphenyls, Leon Creek, San Antonio, Texas, 2012–14

    Science.gov (United States)

    Wilson, Jennifer T.

    2016-06-23

    The Texas Department of State Health Services issued fish consumption advisories in 2003 and 2010 for Leon Creek in San Antonio, Texas, based on elevated concentrations of polychlorinated biphenyls (PCBs) in fish tissues. The U.S. Geological Survey (USGS) measured elevated PCB concentrations in stream-sediment samples collected during 2007–9 from Leon Creek at Lackland Air Force Base (now known as Joint Base San Antonio-Lackland; the sampling site at this base is hereinafter referred to as the “Joint Base site”) and sites on Leon Creek downstream from the base. This report describes the occurrence and concentrations of selected trace elements and halogenated organic compounds (pesticides, flame retardants, and PCBs) and potential sources of PCBs in stream-sediment samples collected from four sites on Leon Creek during 2012–14. In downstream order, sediment samples were collected from Leon Creek at northwest Interstate Highway 410 (Loop 410), Rodriguez Park, Morey Road, and Joint Base. The USGS periodically collected streambed-sediment samples during low flow and suspended-sediment samples during high flow.

  8. Federal technology alert. Parabolic-trough solar water heating

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1998-04-01

    Parabolic-trough solar water heating is a well-proven renewable energy technology with considerable potential for application at Federal facilities. For the US, parabolic-trough water-heating systems are most cost effective in the Southwest where direct solar radiation is high. Jails, hospitals, barracks, and other facilities that consistently use large volumes of hot water are particularly good candidates, as are facilities with central plants for district heating. As with any renewable energy or energy efficiency technology requiring significant initial capital investment, the primary condition that will make a parabolic-trough system economically viable is if it is replacing expensive conventional water heating. In combination with absorption cooling systems, parabolic-trough collectors can also be used for air-conditioning. Industrial Solar Technology (IST) of Golden, Colorado, is the sole current manufacturer of parabolic-trough solar water heating systems. IST has an Indefinite Delivery/Indefinite Quantity (IDIQ) contract with the Federal Energy Management Program (FEMP) of the US Department of Energy (DOE) to finance and install parabolic-trough solar water heating on an Energy Savings Performance Contract (ESPC) basis for any Federal facility that requests it and for which it proves viable. For an ESPC project, the facility does not pay for design, capital equipment, or installation. Instead, it pays only for guaranteed energy savings. Preparing and implementing delivery or task orders against the IDIQ is much simpler than the standard procurement process. This Federal Technology Alert (FTA) of the New Technology Demonstration Program is one of a series of guides to renewable energy and new energy-efficient technologies.

  9. A new very high energy gamma ray detector using two 11 meter diameter parabolic mirrors in coincidence

    Science.gov (United States)

    Tuemer, O. T.; Siemieniewski, J.; Zych, A. D.; Akerlof, C. W.; Horner, S. D.; Arbic, B.; Meyer, D., I.; Tschirhart, R. S.; Wheaton, W. A.; MacCallum, C.

    Gamma Star, a new Very High Energy (VHE) gamma ray detector has been constructed at the Solar Thermal Test Facility of Sandia National Laboratories in Albuquerque, New Mexico. The detector is based on three large parabolic solar concentrators with a total collection area of 228 square meters. The goal of this experiment is to find ways of significantly improving current techniques of ground-based gamma ray observations. Initial tests, performed in the fall of 1986, are reported here.

  10. Regularity for solutions of non local parabolic equations

    CERN Document Server

    Lara, Héctor A Chang

    2011-01-01

    We study the regularity of solutions of parabolic fully nonlinear nonlocal equations. We proof $C^\\a$ regularity in space and time and for translation invariant equations and under different assumptions on the kernels $C^{1,\\a}$ in space and time regularity. The proofs rely on a weak parabolic ABP inspired in recent work done by L. Silvestre and the classic ideas of K. Tso and L. Wang. Our results remain uniform as $\\s\\to2$ allowing us to understand the non local theory as an extension to the classical one.

  11. NEW ALTERNATING DIRECTION FINITE ELEMENT SCHEME FOR NONLINEAR PARABOLIC EQUATION

    Institute of Scientific and Technical Information of China (English)

    崔霞

    2002-01-01

    A new alternating direction (AD) finite element (FE) scheme for 3-dimensional nonlinear parabolic equation and parabolic integro-differential equation is studied. By using AD,the 3-dimensional problem is reduced to a family of single space variable problems, calculation work is simplified; by using FE, high accuracy is kept; by using various techniques for priori estimate for differential equations such as inductive hypothesis reasoning, the difficulty arising from the nonlinearity is treated. For both FE and ADFE schemes, the convergence properties are rigorously demonstrated, the optimal H1- and L2-norm space estimates and the O((△t)2) estimate for time variable are obtained.

  12. Focusing of Intense Laser via Parabolic Plasma Concave Surface

    Science.gov (United States)

    Zhou, Weimin; Gu, Yuqiu; Wu, Fengjuan; Zhang, Zhimeng; Shan, Lianqiang; Cao, Leifeng; Zhang, Baohan

    2015-12-01

    Since laser intensity plays an important role in laser plasma interactions, a method of increasing laser intensity - focusing of an intense laser via a parabolic plasma concave surface - is proposed and investigated by three-dimensional particle-in-cell simulations. The geometric focusing via a parabolic concave surface and the temporal compression of high harmonics increased the peak intensity of the laser pulse by about two orders of magnitude. Compared with the improvement via laser optics approaches, this scheme is much more economic and appropriate for most femtosecond laser facilities. supported by National Natural Science Foundation of China (Nos. 11174259, 11175165), and the Dual Hundred Foundation of China Academy of Engineering Physics

  13. General difference schemes with intrinsic parallelism for nonlinear parabolic systems

    Institute of Scientific and Technical Information of China (English)

    周毓麟; 袁光伟

    1997-01-01

    The boundary value problem for nonlinear parabolic system is solved by the finite difference method with intrinsic parallelism. The existence of the discrete vector solution for the general finite difference schemes with intrinsic parallelism is proved by the fixed-point technique in finite-dimensional Euclidean space. The convergence and stability theorems of the discrete vector solutions of the nonlinear difference system with intrinsic parallelism are proved. The limitation vector function is just the unique generalized solution of the original problem for the parabolic system.

  14. Nonlinear Parabolic Equations with Singularities in Colombeau Vector Spaces

    Institute of Scientific and Technical Information of China (English)

    Mirjana STOJANOVI(C)

    2006-01-01

    We consider nonlinear parabolic equations with nonlinear non-Lipschitz's term and singular initial data like Dirac measure, its derivatives and powers. We prove existence-uniqueness theorems in Colombeau vector space gC1,w2,2([O,T),Rn),n ≤ 3. Due to high singularity in a case of parabolic equation with nonlinear conservative term we employ the regularized derivative for the conservative term, in order to obtain the global existence-uniqueness result in Colombeau vector space gC1,L2([O,T),Rn),n ≤ 3.

  15. Particulates and organic compounds from wood firing - new investigations of emissions and concentrations; Partikler og organiske forbindelser fra traefyring - nye undersoegelser af udslip og koncentrationer

    Energy Technology Data Exchange (ETDEWEB)

    Glasius, M.; Konggaard, P.; Stubkjaer, J.; Bossi, R.; Hertel, O.; Ketzel, M.; Waehlin, P.; Schleicher, O.; Palmgren, F.

    2007-03-15

    Recent Danish as well as international studies have shown that wood burning may lead to increased levels air pollution levels of particles and different types of organic compounds in the vicinity of the sources. The air pollution constitutes a health risk for the local population but this risk is poorly quantified. Furthermore, the number of available studies is relatively limited with regard to pollutant emissions and concentrations related to wood burning. This report summarizes a number of studies which have the aim of contributing to the current understanding of the air pollution problem related to the use of wood stoves and boilers. The investigations include studies of emissions and resulting outdoor pollutant levels in two villages. Furthermore investigations of indoor-outdoor levels have been performed in two single-family detached houses. (au)

  16. Determination of the concentration of nitrogenous bio-organic compounds using an isotope ratio mass spectrometer operating in continuous flow mode.

    Science.gov (United States)

    Tea, Illa; Kosieradzka, Katarzyna; Antheaume, Ingrid; Gentil, Emmanuel; Robins, Richard J

    2011-09-01

    The quality of the determination of compound-specific isotopic content at natural abundance by gas chromatography-isotope ratio measurement-mass spectrometry (GC-irm-MS) relies on the stability of the voltage generated by the ion detector Faraday cages. The application of GC-irm-MS to the determination of δ(13)C (‰) and δ(15)N (‰) is now routine. However, for numerous applications, it is necessary to determine both the isotope content (δ(15)N) and the quantity (in micromoles) of analyte present. We now show that it is possible for nitrogen-containing compounds to measure how much analyte is present with an irm mass spectrometer linked to a GC by exploiting the integrated N(2) total ion current intensity (Vs) generated by measuring the (15)N/(14)N isotope ratio. The method is validated over a range of concentration (2-70 mmol/L) and δ(15)N (-70 to +50‰) values for six molecules of diverse chemical nature and functionality (nortropine, norpseudotropine, nortropinone, cysteine, taurine, glutathione). It is shown that once the ion current is calibrated, the quantitative values are of a comparable quality to those obtained from GC with flame ionization detection (GC-FID). In addition, it is demonstrated that over a definable range, the δ(15)N (‰) value is independent of the quantity of analyte introduced, confirming the validity of this method.

  17. Some remarks on singular solutions of nonlinear elliptic equations. III: viscosity solutions, including parabolic operators

    CERN Document Server

    Caffarelli, Luis; Nirenberg, Louis

    2011-01-01

    The paper concerns singular solutions of nonlinear elliptic equations, which include removable singularities for viscosity solutions, a strengthening of the Hopf Lemma including parabolic equations, Strong maximum principle and Hopf Lemma for viscosity solutions including also parabolic equations.

  18. 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 parabolic equations with dependent coefficients are established.

  19. On the regularity of optimal control for a parabolic system of order 2m

    Directory of Open Access Journals (Sweden)

    Ornella Fiodo

    1992-05-01

    Full Text Available An optimal control problem for a parabolic operator of order 2m with the boundary conditions containing the control is considered. A regularity theorem for the parabolic problem and the regularity of the optimal control is proved.

  20. Regional assessment of concentrations and sources of pharmaceutically active compounds, pesticides, nitrate, and E. coli in post-glacial aquifer environments (Canada).

    Science.gov (United States)

    Saby, Marion; Larocque, Marie; Pinti, Daniele L; Barbecot, Florent; Gagné, Sylvain; Barnetche, Diogo; Cabana, Hubert

    2017-02-01

    There is growing concern worldwide about the exposure of groundwater resources to pharmaceutically active compounds (PhACs) and agricultural contaminants, such as pesticides, nitrate, and Escherichia coli. For regions with a low population density and an abundance of water, regional contamination assessments are not carried out systematically due to the typically low concentrations and high costs of analyses. The objectives of this study were to evaluate regional-scale contaminant distributions in untreated groundwater in a rural region of Quebec (Canada). The geological and hydrogeological settings of this region are typical of post-glacial regions around the world, where groundwater flow can be complex due to heterogeneous geological conditions. A new spatially distributed Anthropogenic Footprint Index (AFI), based on land use data, was developed to assess surface pollution risks. The Hydrogeochemical Vulnerability Index (HVI) was computed to estimate aquifer vulnerability. Nine wells had detectable concentrations of one to four of the 13 tested PhACs, with a maximum concentration of 116ng·L(-1) for benzafibrate. A total of 34 of the 47 tested pesticides were detected in concentrations equal to or greater than the detection limit, with a maximum total pesticide concentration of 692ng·L(-1). Nitrate concentrations exceeded 1mg·L(-1) N-NO3 in 15.3% of the wells, and the Canadian drinking water standard was exceeded in one well. Overall, 13.5% of the samples had detectable E. coli. Including regional-scale sources of pollutants to the assessment of aquifer vulnerability with the AFI did not lead to the identification of contaminated wells, due to the short groundwater flow paths between recharge and the sampled wells. Given the occurrence of contaminants, the public health concerns stemming from these new data on regional-scale PhAC and pesticide concentrations, and the local flow conditions observed in post-glacial terrains, there is a clear need to investigate

  1. A strain of Saccharomyces cerevisiae evolved for fermentation of lignocellulosic biomass displays improved growth and fermentative ability in high solids concentrations and in the presence of inhibitory compounds

    Directory of Open Access Journals (Sweden)

    Hawkins Gary M

    2011-11-01

    Full Text Available Abstract Background Softwoods are the dominant source of lignocellulosic biomass in the northern hemisphere, and have been investigated worldwide as a renewable substrate for cellulosic ethanol production. One challenge to using softwoods, which is particularly acute with pine, is that the pretreatment process produces inhibitory compounds detrimental to the growth and metabolic activity of fermenting organisms. To overcome the challenge of bioconversion in the presence of inhibitory compounds, especially at high solids loading, a strain of Saccharomyces cerevisiae was subjected to evolutionary engineering and adaptation for fermentation of pretreated pine wood (Pinus taeda. Results An industrial strain of Saccharomyces, XR122N, was evolved using pretreated pine; the resulting daughter strain, AJP50, produced ethanol much more rapidly than its parent in fermentations of pretreated pine. Adaptation, by preculturing of the industrial yeast XR122N and the evolved strains in 7% dry weight per volume (w/v pretreated pine solids prior to inoculation into higher solids concentrations, improved fermentation performance of all strains compared with direct inoculation into high solids. Growth comparisons between XR122N and AJP50 in model hydrolysate media containing inhibitory compounds found in pretreated biomass showed that AJP50 exited lag phase faster under all conditions tested. This was due, in part, to the ability of AJP50 to rapidly convert furfural and hydroxymethylfurfural to their less toxic alcohol derivatives, and to recover from reactive oxygen species damage more quickly than XR122N. Under industrially relevant conditions of 17.5% w/v pretreated pine solids loading, additional evolutionary engineering was required to decrease the pronounced lag phase. Using a combination of adaptation by inoculation first into a solids loading of 7% w/v for 24 hours, followed by a 10% v/v inoculum (approximately equivalent to 1 g/L dry cell weight into 17

  2. Investigation of all-in-fiber Yb doped femtosecond fiber oscillator for generation of parabolic pulses in normal dispersion fiber amplifier

    Science.gov (United States)

    Frankinas, S.; Bartulevicius, T.; Michailovas, A.; Rusteika, N.

    2017-07-01

    In this work femtosecond passively mode-locked environmentally stable Ytterbium fiber oscillator generating pulses with duration of 380 fs is presented. Short pulse duration and smooth spectrum were obtained from the oscillator using chirped fiber Bragg grating with very low anomalous chromatic dispersion (0.15 ps2) and semiconductor saturable absorber mirror. Linearly chirped parabolic pulses were produced after amplification of the oscillator pulses in low concentration ytterbium doped fiber amplifier. Transform limited duration of the generated parabolic pulses was 110 fs.

  3. Evaluation of Ultra-Violet Photocatalytic Oxidation (UVPCO) forIndoor Air Applications: Conversion of Volatile Organic Compounds at LowPart-per-Billion Concentrations

    Energy Technology Data Exchange (ETDEWEB)

    Hodgson, Alfred T.; Sullivan, Douglas P.; Fisk, William J.

    2005-09-30

    Efficient removal of indoor generated airborne particles and volatile organic compounds (VOCs) in office buildings and other large buildings may allow for a reduction in outdoor air supply rates with concomitant energy savings while still maintaining acceptable indoor air quality in these buildings. Ultra-Violet Photocatalytic Oxidation (UVPCO) air cleaners have the potential to achieve the necessary reductions in indoor VOC concentrations at relatively low cost. In this study, laboratory experiments were conducted with a scaled, prototype UVPCO device designed for use in a duct system. The experimental UVPCO contained two 30 by 30-cm honeycomb monoliths coated with titanium dioxide and 3% by weight tungsten oxide. The monoliths were irradiated with 12 UVC lamps arranged in four banks. The UVPCO was challenged with four mixtures of VOCs typical of mixtures encountered in indoor air. A synthetic office mixture contained 27 VOCs commonly measured in office buildings. A cleaning product mixture contained three cleaning products with high market shares. A building product mixture was created by combining sources including painted wallboard, composite wood products, carpet systems, and vinyl flooring. A fourth mixture contained formaldehyde and acetaldehyde. Steady-state concentrations were produced in a classroom laboratory or a 20-m{sup 3} environmental chamber. Air was drawn through the UVPCO, and single pass conversion efficiencies were measured from replicate air samples collected upstream and downstream of the reactor section. Concentrations of the mixtures were manipulated, with concentrations of individual VOCs mostly maintained below 10 ppb. Device flow rates were varied between 165 and 580 m{sup 3}/h. Production of formaldehyde, acetaldehyde, acetone, formic acid, and acetic acid as reaction products was investigated. Conversion efficiency data were generated for 48 individual VOCs or groups of closely related compounds. Alcohols and glycol ethers were the

  4. The impact of water and hydrocarbon concentration on the sensitivity of a polymer-based quartz crystal microbalance sensor for organic compounds

    Energy Technology Data Exchange (ETDEWEB)

    Pejcic, Bobby, E-mail: Bobby.Pejcic@csiro.au [CSIRO, Earth Science and Resource Engineering, PO Box 1130, Bentley, WA 6102 (Australia); Crooke, Emma [CSIRO, Earth Science and Resource Engineering, PO Box 1130, Bentley, WA 6102 (Australia); Doherty, Cara M.; Hill, Anita J. [CSIRO, Materials Science and Engineering, Locked Bag 33, Clayton Sth MDC, Vic 3169 (Australia); Myers, Matthew [CSIRO, Earth Science and Resource Engineering, PO Box 1130, Bentley, WA 6102 (Australia); University of Western Australia, School of Biomedical, Biomolecular and Chemical Sciences, Crawley, WA 6009 (Australia); Qi, Xiubin; Ross, Andrew [CSIRO, Earth Science and Resource Engineering, PO Box 1130, Bentley, WA 6102 (Australia)

    2011-10-03

    Highlights: {yields} The response of a polymer coated QCM sensor is affected by water soaking time. {yields} Polymer-water interfacial processes influence the QCM sensitivity for hydrocarbons. {yields} The QCM sensitivity of high Tg polymer films is affected by plasticization processes. - Abstract: Long-term environmental monitoring of organic compounds in natural waters requires sensors that respond reproducibly and linearly over a wide concentration range, and do not degrade with time. Although polymer coated piezoelectric based sensors have been widely used to detect hydrocarbons in aqueous solution, very little information exists regarding their stability and suitability over extended periods in water. In this investigation, the influence of water aging on the response of various polymer membranes [polybutadiene (PB), polyisobutylene (PIB), polystyrene (PS), polystyrene-co-butadiene (PSB)] was studied using the quartz crystal microbalance (QCM). QCM measurements revealed a modest increase in sensitivity towards toluene for PB and PIB membranes at concentrations above 90 ppm after aging in water for 4 days. In contrast, the sensitivity of PS and PSB coated QCM sensors depended significantly on the toluene concentration and increased considerably at concentrations above 90 ppm after aging in water for 4 days. Attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) showed that there is a change in the sorption mechanism at higher toluene levels for PS and PSB. Positron annihilation lifetime spectroscopy (PALS) studies were performed to investigate the free volume properties of all polymers and to monitor any changes in the free volume size and distribution due to water and toluene exposure. The PALS did not detect any considerable variation in the free volume properties of the polymer films as a function of solution composition and soaking time, implying that viscoelastic and/or interfacial processes (i.e. surface area changes) are probably

  5. Environmental contaminant mixtures at ambient concentrations invoke a metabolic stress response in goldfish not predicted from exposure to individual compounds alone.

    Science.gov (United States)

    Jordan, Julia; Zare, Ava; Jackson, Leland J; Habibi, Hamid R; Weljie, Aalim M

    2012-02-03

    Environmental contaminants from wastewater and industrial or agricultural areas are known to have adverse effects on development, reproduction, and metabolism. However, reliable assessment of environmental contaminant impact at low (i.e., ambient) concentrations using genomics and transcriptomics approaches has proven challenging. A goldfish model was used to investigate the effects of aquatic pollutant exposure in vivo by means of quantitative nuclear magnetic resonance metabolomics in multiple organs to elucidate a system-wide response. Animals were exposed to 4,4'-isopropylidenediphenol (Bisphenol-A, BPA), di-(2-ethylhexyl)-phthalate (DEHP), and nonylphenol (NP). Metabolite-specific spectral analysis combined with pathway-driven bioinformatics indicated changes in energy and lipid metabolism in liver following exposure to individual contaminants and a tertiary mixture. A dissimilar response in testis exposed to DEHP and mixture indicates disrupted AMPK and cAMP signaling. Uniquely, our observations (1) suggest that exposure to a contaminant mixture is characterized by a stress response not predicted from exposure to individual contaminants, even in the absence of other phenotypic features and (2) demonstrate the sensitivity of metabolomics in risk-assessment of environmental toxicant mixtures at ambient concentrations by detecting early stage metabolic dysregulation. These findings have general applicability in the assessment of "benign" compound mixtures in environmental and pharmaceutical development.

  6. Pre-concentration of phenolic compounds in water samples by novel liquid-liquid microextraction and determination by gas chromatography-mass spectrometry.

    Science.gov (United States)

    Faraji, Hakim; Tehrani, Mohammad Saber; Husain, Syed Waqif

    2009-12-04

    Pre-concentration and determination of 8 phenolic compounds in water samples has been achieved by in situ derivatization and using a new liquid-liquid microextraction coupled GC-MS system. Microextraction efficiency factors have been investigated and optimized: 9 microL 1-undecanol microdrop exposed for 15 min floated on surface of a 10 mL water sample at 55 degrees C, stirred at 1200 rpm, low pH level and saturated salt conditions. Chromatographic problems associated with free phenols have been overcome by simultaneous in situ derivatization utilizing 40 microL of acetic anhydride and 0.5% (w/v) K(2)CO(3). Under the selected conditions, pre-concentration factor of 235-1174, limit of detection of 0.005-0.68 microg/L (S/N=3) and linearity range of 0.02-300 microg/L have been obtained. A reasonable repeatability (RSD or =r(2)> or =0.9975) of results illustrated a good performance of the present method. The relative recovery of different natural water samples was higher than 84%.

  7. Design and Development of Prototype Cylindrical Parabolic Solar Collector for Water Heating Application

    Directory of Open Access Journals (Sweden)

    Hrushikesh Bhujangrao Kulkarni

    2016-02-01

    Full Text Available Concentrating collectors absorbs solar energy and convert it into heat for generating hot water, steam at required temperature, which can be further used for solar thermal applications. The developing countries like India where solar energy is abundantly available; there is need to develop technology for harnessing solar energy for power production, but the main problem associated with concentrating solar power technology is the high cost of installation and low output efficiency. To solve this problem, a prototype cylindrical parabolic solar collector having aperture area of 1.89 m2 is designed and developed using low cost highly reflecting and absorbing material to reduce initial cost of project and improve thermal efficiency. ASHRAE Standard 93, 1986 was used to evaluate the thermal performance and it was observed that this system can generate hot water at an average temperature of 500C per day with an average efficiency of 49% which is considerable higher than flat plate solar collectors. Hot water produced by this system can be useful for domestic, agricultural, industrial process heat applications.Article History: Received Sept 19, 2015; Received in revised form Dec 23, 2015; Accepted February 2, 2016; Available online How to Cite This Article: Bhujangrao, K.H. (2016. Design and Development of Prototype Cylindrical Parabolic Solar Collector for Water Heating Application. International Journal of Renewable Energy Development, 5(1, 49-55 http://dx.doi.org/10.14710/ijred.5.1.49-55 

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1982-08-01

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

  9. Hydrogen reduction in heat transfer fluid in parabolic trough CSP plants

    Science.gov (United States)

    Lang, Christoph; Belkheir, Mohamed; Kim, Eungkyu; Davidson, Chet; Holden, Bruce; Hook, Bruce

    2017-06-01

    Hydrogen (H2) has been found to be generated in very small proportions when diphenyl oxide/ biphenyl heat transfer fluid (HTF) is operated at temperatures close to 400°C. At such temperatures, H2 can permeate through steel walls to the vacuum space of parabolic trough (PT) solar receivers, where it increases heat losses that can significantly impact the economics of PT concentrated solar power plants. A novel process for the reduction of the H2 concentration in HTF via stripping and gas separation has been simulated for the operation in PT CSP plants. Applying the proposed process, the concentration of H2 in HTF can be reduced down to 1 ppb. A cost comparison between the H2 separation process and frequent PT receivers replacement was conducted and found that proposed H2 removal process is more economic.

  10. Benzalkonium chloride (BAC) and dimethyldioctadecyl-ammonium bromide (DDAB), two common quaternary ammonium compounds, cause genotoxic effects in mammalian and plant cells at environmentally relevant concentrations.

    Science.gov (United States)

    Ferk, F; Misík, M; Hoelzl, C; Uhl, M; Fuerhacker, M; Grillitsch, B; Parzefall, W; Nersesyan, A; Micieta, K; Grummt, T; Ehrlich, V; Knasmüller, S

    2007-11-01

    Quaternary ammonium compounds (QACs) are cationic surfactants that are widely used as disinfectants. In the present study, we tested two important representatives, namely, benzalkonium chloride (BAC) and dimethyldioctadecyl-ammonium bromide (DDAB) in four genotoxicity tests, namely, in the Salmonella/microsome assay with strains TA 98, TA 100 and TA 102, in the single-cell gel electrophoresis (SCGE) assay with primary rat hepatocytes and in micronucleus (MN) assays with peripheral human lymphocytes and with root tip cells of Vicia faba. In the bacterial experiments, consistently negative results were obtained in the dose range between 0.001 and 110 microg per plate in the presence and absence of metabolic activation while significant induction of DNA migration was detected in the liver cells. With BAC, a moderate but significant effect was found with an exposure concentration of 1.0 mg/l while DDAB caused damage at lower doses (0.3 mg/l). The effects were not altered when the nuclei were treated with formamidopyridine glycosylase, indicating that they are not due to formation of oxidized purines. The MN assays with blood cells were carried out under identical conditions to the SCGE experiments and a significant increase was seen at the highest dose levels (BAC: 1.0 and 3.0 mg/l; DDAB: 1 mg/l). Both compounds also caused significant induction of MN as well as inhibition of cell division in plant cells, the lowest effective levels were 1.0 and 10 mg/l for DDAB and BAC, respectively. Our findings show that both chemicals induce moderate but significant genotoxic effects in eukaryotic cells at concentrations which are found in wastewaters and indicate that their release into the environment may cause genetic damage in exposed organisms. Furthermore, the direct contact of humans to QAC-containing detergents and pharmaceuticals that contain substantially higher concentrations than those which were required to cause effects in eukaryotic cells in the present study should

  11. A parabolic singular perturbation problem with an internal layer

    NARCIS (Netherlands)

    Grasman, J.; Shih, S.D.

    2004-01-01

    A method is presented to approximate with singular perturbation methods a parabolic differential equation for the quarter plane with a discontinuity at the corner. This discontinuity gives rise to an internal layer. It is necessary to match the local solution in this layer with the one in a corner l

  12. Proton driven plasma wakefield generation in a parabolic plasma channel

    Science.gov (United States)

    Golian, Y.; Dorranian, D.

    2016-11-01

    An analytical model for the interaction of charged particle beams and plasma for a wakefield generation in a parabolic plasma channel is presented. In the suggested model, the plasma density profile has a minimum value on the propagation axis. A Gaussian proton beam is employed to excite the plasma wakefield in the channel. While previous works investigated on the simulation results and on the perturbation techniques in case of laser wakefield accelerations for a parabolic channel, we have carried out an analytical model and solved the accelerating field equation for proton beam in a parabolic plasma channel. The solution is expressed by Whittaker (hypergeometric) functions. Effects of plasma channel radius, proton bunch parameters and plasma parameters on the accelerating processes of proton driven plasma wakefield acceleration are studied. Results show that the higher accelerating fields could be generated in the PWFA scheme with modest reductions in the bunch size. Also, the modest increment in plasma channel radius is needed to obtain maximum accelerating gradient. In addition, the simulations of longitudinal and total radial wakefield in parabolic plasma channel are presented using LCODE. It is observed that the longitudinal wakefield generated by the bunch decreases with the distance behind the bunch while total radial wakefield increases with the distance behind the bunch.

  13. Viscosity solutions of fully nonlinear functional parabolic PDE

    Directory of Open Access Journals (Sweden)

    Liu Wei-an

    2005-01-01

    Full Text Available By the technique of coupled solutions, the notion of viscosity solutions is extended to fully nonlinear retarded parabolic equations. Such equations involve many models arising from optimal control theory, economy and finance, biology, and so forth. The comparison principle is shown. Then the existence and uniqueness are established by the fixed point theory.

  14. Almost periodic solutions to systems of parabolic equations

    Directory of Open Access Journals (Sweden)

    Janpou Nee

    1994-01-01

    Full Text Available In this paper we show that the second-order differential solution is 2-almost periodic, provided it is 2-bounded, and the growth of the components of a non-linear function of a system of parabolic equation is bounded by any pair of con-secutive eigenvalues of the associated Dirichlet boundary value problems.

  15. Improved Green's function parabolic equation method for atmospheric sound propagation

    NARCIS (Netherlands)

    Salomons, E.M.

    1998-01-01

    The numerical implementation of the Green's function parabolic equation (GFPE) method for atmospheric sound propagation is discussed. Four types of numerical errors are distinguished: (i) errors in the forward Fourier transform; (ii) errors in the inverse Fourier transform; (iii) errors in the refra

  16. Stability test for a parabolic partial differential equation

    NARCIS (Netherlands)

    Vajta, Miklos

    2001-01-01

    The paper describes a stability test applied to coupled parabolic partial differential equations. The PDE's describe the temperature distribution of composite structures with linear inner heat sources. The distributed transfer functions are developed based on the transmission matrix of each layer.

  17. Nyquist stability test for a parabolic partial differential equation

    NARCIS (Netherlands)

    Vajta, Miklos; Hamza, M.H.

    2000-01-01

    The paper describes a Nyquist stability test applied to a parabolic partial differential equation. The PDE describes the temperature distribution of composite structures with linear inner heat source. The distributed transfer functions have been developed by the transmission matrix method. To

  18. The ellipse in parabolic motion: An undergraduate experiment

    Science.gov (United States)

    Carrillo-Bernal, M. A.; Mancera-Piña, P. E.; Cerecedo-Núñez, H. H.; Padilla-Sosa, P.; Núñez-Yépez, H. N.; Salas-Brito, A. L.

    2014-04-01

    We present a simple method of experimentally studying the elliptic shape of the joined apices of parabolic projectile trajectories in the undergraduate laboratory. The experimental data agrees well with theoretical results, and we find that this experiment provides an interesting twist to the venerable undergraduate experiment on projectile motion.

  19. On some perturbation techniques for quasi-linear parabolic equations

    Directory of Open Access Journals (Sweden)

    Igor Malyshev

    1990-01-01

    Full Text Available We study a nonhomogeneous quasi-linear parabolic equation and introduce a method that allows us to find the solution of a nonlinear boundary value problem in “explicit” form. This task is accomplished by perturbing the original equation with a source function, which is then found as a solution of some nonlinear operator equation.

  20. MULTIGRID FOR THE MORTAR FINITE ELEMENT FOR PARABOLIC PROBLEM

    Institute of Scientific and Technical Information of China (English)

    Xue-jun Xu; Jin-ru Chen

    2003-01-01

    In this paper, a mortar finite element method for parabolic problem is presented. Multigrid method is used for solving the resulting discrete system. It is shown that the multigrid method is optimal, I.e, the convergence rate is independent of the mesh size L and the time step parameter т.