WorldWideScience

Sample records for spectrally selective solar

  1. Spectrally selective solar energy materials

    International Nuclear Information System (INIS)

    Sikkens, M.

    1981-01-01

    The performance and properties of spectrally selective materials are considered and, in particular, the selective absorption of solar radiation by free electrons is discussed, both in a homogeneous material in which these electrons are strongly scattered, and in a composite material consisting of small metal particles in a dielectric host. Such materials can be used as selective absorbers if they are deposited as a thin film onto a metal substrate, the latter providing the required low emittance. This type of selective surfaces is produced by reactive sputtering of Ni in an Ar/CH 4 gas mixture. This method can yield Ni films with a considerable carbon concentration. The carbon concentration can be varied over a wide range by adjusting the partial methane pressure. The associated experimental techniques are discussed. As the carbon concentration increases, the structure of the films changes from a Ni phase in which carbon is dissolved, via an intermediate Ni 3 C phase into an amorphous carbon phase with a high electrical resistivity in which small nickel particles are embedded. Both mechanisms of selective absorption by free electrons are observed and are found to be well described by rather simple models. The best selectivity is obtained at high carbon concentrations where the films consist of nickel particles in carbon. Depending on the film thickness and the substrate material, the solar absorptance varies between 0.78 and 0.90, while the thermal emittance varies between 0.025 and 0.04. Since the films are found to be stable at 400 0 C in vacuum, it appears that these films are good candidates for application in photothermal solar energy conversion at temperature levels around 200 0 C and higher. (Auth.)

  2. CuO-PANI nanostructure with tunable spectral selectivity for solar selective coating application

    Energy Technology Data Exchange (ETDEWEB)

    Cindrella, L., E-mail: cind@nitt.edu; Prabhu, S., E-mail: sprabhuk@gmail.com

    2016-08-15

    Highlights: • CuO-PANI nanostructure has been reported as the solar selective absorber coating. • Solar selectivity and efficiency of the coatings have been evaluated. • PANI provides a surface texture favourable for multiple reflection. - Abstract: CuO-PANI nanostructure has been demonstrated as the solar selective absorber coating for the first time. The effortless chemical methods and easily scalable techniques such as precipitation, in-situ polymerization and spray coating were adopted for the fabrication of CuO nanorods and CuO-PANI nanostructures for solar application. The synthesis was carried out without using any template. The morphology and phase structure of fabricated CuO nanorods and CuO-PANI nanostructure coatings were studied by atomic force microscopy, scanning electron microscopy and X-ray diffraction analysis. The energy dispersive X-ray spectra and elemental mapping confirm the presence of the chosen elements in the nanostructure. The solar absorptance (α{sub s}), thermal emittance (ε{sub t}) and selectivity (ξ) of the nanostructure coatings on glass substrate were optimized to 0.94, 0.01 and 94 respectively by changing the polyaniline content on the surface of the CuO nanorods. The efficiency of the solar selective coatings were evaluated. The optimized solar absorber coating of CuO-PANI nanostructure is highly promising for its selective optical properties.

  3. Spectrally selective glazings

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1998-08-01

    Spectrally selective glazing is window glass that permits some portions of the solar spectrum to enter a building while blocking others. This high-performance glazing admits as much daylight as possible while preventing transmission of as much solar heat as possible. By controlling solar heat gains in summer, preventing loss of interior heat in winter, and allowing occupants to reduce electric lighting use by making maximum use of daylight, spectrally selective glazing significantly reduces building energy consumption and peak demand. Because new spectrally selective glazings can have a virtually clear appearance, they admit more daylight and permit much brighter, more open views to the outside while still providing the solar control of the dark, reflective energy-efficient glass of the past. This Federal Technology Alert provides detailed information and procedures for Federal energy managers to consider spectrally selective glazings. The principle of spectrally selective glazings is explained. Benefits related to energy efficiency and other architectural criteria are delineated. Guidelines are provided for appropriate application of spectrally selective glazing, and step-by-step instructions are given for estimating energy savings. Case studies are also presented to illustrate actual costs and energy savings. Current manufacturers, technology users, and references for further reading are included for users who have questions not fully addressed here.

  4. Designing spectrally-selective mirrors for use in luminescent solar concentrators

    Science.gov (United States)

    Connell, Ryan; Pinnell, Christian; Ferry, Vivian E.

    2018-02-01

    Spectrally-selective mirrors improve the performance of luminescent solar concentrators (LSCs) by trapping emitted light within the waveguide. However, this beneficial property comes with a spectral restriction on incident sunlight that enters the concentrator. Especially for luminophores with overlap between the absorption and emission bands, design of the spectrally-selective mirrors requires a tradeoff between transmission of incident sunlight and trapping of luminescent photons. In this paper, we explore how the design of a spectrally-selective top mirror changes for LSCs containing luminophores of varying loading fractions, quantum yield, and overlap between the absorption and emission spectra, as well as LSCs with different back reflectors and lateral sizes. Using CdSe/CdS core/shell nanocrystals as the luminophore, we find that specific conditions favor different mirror designs. Mirrors designed to trap luminescent light have higher predicted performance than mirrors designed for sunlight transmission when the luminophore quantum yield is greater than 0.85, the luminophore optical density is less than 1.4 at 450 nm, the lateral size of the concentrator is greater than 10 cm, or there is low overlap between the luminophore absorption and emission. Mirrors optimized for either transmission or luminescence trapping have comparable performance for quantum yields less than 0.85, and the other conditions favor mirrors optimized for light transmission. For a LSC with unity quantum yield, a lateral size of 1 m × 1 m, and a mirror designed to trap luminescent light, a concentration factor of 37× is possible, as compared to 10× for a LSC with an open top. This research indicates the importance of tailoring the design of the spectrally-selective top mirror to the properties of the luminophore and LSC.

  5. Spectral reflectance properties of black chrome for use as a solar selective coating

    Science.gov (United States)

    Mcdonald, G. E.

    1974-01-01

    The NASA-Lewis Research Center has determined that a widely available commercially electroplated decorative finish known as black chrome has desirable solar selective properties. Black chrome electroplated coating has high absorbtance in the solar spectrum and low emissivity in the 250 F blackbody thermal spectrum. The spectral reflectance properties of a commercially prepared black chrome on steel have been measured. Values are presented for reflectance of the black chrome, and compared with the reflectance of black paint and with two available samples of black nickel which had been prepared for solar selective properties. The reflectance of black chrome, of the two black nickels, and of black paint integrated over the solar spectrum for air mass 2 were 0.132, 0.123, 0.133, and 0.033, respectively. The reflectance of the black chrome, two black nickels, and of the black paint integrated over the blackbody spectrum for 250 F from 3 to 15 microns are 0.912, 0.934, 0.891, and 0.033, respectively. These reflectance measurements indicate absorptivity-to-emissivity values of 9.8, 13.8, 8.0, and 1.00, respectively.

  6. A Novel Approach to Thermal Design of Solar Modules: Selective-Spectral and Radiative Cooling

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Xingshu; Dubey, Rajiv; Chattopadhyay, Shashwata; Khan, Mohammad Ryyan; Chavali, Raghu Vamsi; Silverman, Timothy J.; Kottantharayil, Anil; Vasi, Juzer; Alam, Muhammad Ashraful

    2016-11-21

    For commercial solar modules, up to 80% of the incoming sunlight may be dissipated as heat, potentially raising the temperature 20-30 degrees C higher than the ambient. In the long run, extreme self-heating may erode efficiency and shorten lifetime, thereby, dramatically reducing the total energy output by almost ~10% Therefore, it is critically important to develop effective and practical cooling methods to combat PV self-heating. In this paper, we explore two fundamental sources of PV self-heating, namely, sub-bandgap absorption and imperfect thermal radiation. The analysis suggests that we redesign the optical and thermal properties of the solar module to eliminate the parasitic absorption (selective-spectral cooling) and enhance the thermal emission to the cold cosmos (radiative cooling). The proposed technique should cool the module by ~10 degrees C, to be reflected in significant long-term energy gain (~ 3% to 8% over 25 years) for PV systems under different climatic conditions.

  7. Spectrally-engineered solar thermal photovoltaic devices

    Energy Technology Data Exchange (ETDEWEB)

    Lenert, Andrej; Bierman, David; Chan, Walker; Celanovic, Ivan; Soljacic, Marin; Wang, Evelyn N.; Nam, Young Suk; McEnaney, Kenneth; Kraemer, Daniel; Chen, Gang

    2018-03-27

    A solar thermal photovoltaic device, and method of forming same, includes a solar absorber and a spectrally selective emitter formed on either side of a thermally conductive substrate. The solar absorber is configured to absorb incident solar radiation. The solar absorber and the spectrally selective emitter are configured with an optimized emitter-to-absorber area ratio. The solar thermal photovoltaic device also includes a photovoltaic cell in thermal communication with the spectrally selective emitter. The spectrally selective emitter is configured to permit high emittance for energies above a bandgap of the photovoltaic cell and configured to permit low emittance for energies below the bandgap.

  8. Solar thermal drying of apricots: Effect of spectrally-selective cabinet materials on drying rate and quality metrics (abstract)

    Science.gov (United States)

    Solar thermal (ST) drying is currently not in widespread commercial use due to concerns about slow drying rates and poor product quality. ST dryer cabinets could be constructed from spectrally-selective materials (materials which transmit only certain sunlight wavelength bands), but these types of ...

  9. Unidirectional radiative heat transfer with a spectrally selective planar absorber/emitter for high-efficiency solar thermophotovoltaic systems

    Science.gov (United States)

    Kohiyama, Asaka; Shimizu, Makoto; Yugami, Hiroo

    2016-11-01

    A high-efficiency solar thermophotovoltaic (STPV) system has been demonstrated using spectrally selective planar absorber/emitter systems and a GaSb TPV cell. In this study, a novel approach for designing the STPV system based on the efficiency of unidirectional radiative heat transfer has been introduced. To achieve high extraction and photovoltaic conversion efficiencies, the spectrally selective absorber/emitter based on a coherent perfect absorber composed of a thin molybdenum layer sandwiched between hafnium layers was applied. The extraction efficiency was further investigated with respect to the absorber/emitter area ratio. The experimental efficiency of STPV reached 5.1% with the area ratio of 2.3.

  10. Solar Spectral Irradiance and Climate

    Science.gov (United States)

    Pilewskie, P.; Woods, T.; Cahalan, R.

    2012-01-01

    Spectrally resolved solar irradiance is recognized as being increasingly important to improving our understanding of the manner in which the Sun influences climate. There is strong empirical evidence linking total solar irradiance to surface temperature trends - even though the Sun has likely made only a small contribution to the last half-century's global temperature anomaly - but the amplitudes cannot be explained by direct solar heating alone. The wavelength and height dependence of solar radiation deposition, for example, ozone absorption in the stratosphere, absorption in the ocean mixed layer, and water vapor absorption in the lower troposphere, contribute to the "top-down" and "bottom-up" mechanisms that have been proposed as possible amplifiers of the solar signal. New observations and models of solar spectral irradiance are needed to study these processes and to quantify their impacts on climate. Some of the most recent observations of solar spectral variability from the mid-ultraviolet to the near-infrared have revealed some unexpected behavior that was not anticipated prior to their measurement, based on an understanding from model reconstructions. The atmospheric response to the observed spectral variability, as quantified in climate model simulations, have revealed similarly surprising and in some cases, conflicting results. This talk will provide an overview on the state of our understanding of the spectrally resolved solar irradiance, its variability over many time scales, potential climate impacts, and finally, a discussion on what is required for improving our understanding of Sun-climate connections, including a look forward to future observations.

  11. Solar power conversion system with directionally- and spectrally-selective properties based on a reflective cavity

    Science.gov (United States)

    Boriskina, Svetlana; Kraemer, Daniel; McEnaney, Kenneth; Weinstein, Lee A.; Chen, Gang

    2018-03-13

    Solar power conversion system. The system includes a cavity formed within an enclosure having highly specularly reflecting in the IR spectrum inside walls, the enclosure having an opening to receive solar radiation. An absorber is positioned within the cavity for receiving the solar radiation resulting in heating of the absorber structure. In a preferred embodiment, the system further contains an energy conversion and storage devices thermally-linked to the absorber by heat conduction, convection, far-field or near-field thermal radiation.

  12. High efficiency thermal to electric energy conversion using selective emitters and spectrally tuned solar cells

    Science.gov (United States)

    Chubb, Donald L.; Flood, Dennis J.; Lowe, Roland A.

    1992-01-01

    Thermophotovoltaic (TPV) systems are attractive possibilities for direct thermal-to-electric energy conversion, but have typically required the use of black body radiators operating at high temperatures. Recent advances in both the understanding and performance of solid rare-earth oxide selective emitters make possible the use of TPV at temperatures as low as 1500 K. Depending on the nature of parasitic losses, overall thermal-to-electric conversion efficiencies greater than 20 percent are feasible.

  13. UARS Solar Ultraviolet Spectral Irradiance Monitor (SUSIM) Level 3BS V001

    Data.gov (United States)

    National Aeronautics and Space Administration — The Solar Ultraviolet Spectral Irradiance Monitor (SUSIM) Level 3BS data product consists of daily, 1 nm resolution, solar spectral irradiances and selected solar...

  14. Toward a High-Efficient Utilization of Solar Radiation by Quad-Band Solar Spectral Splitting

    OpenAIRE

    Cao, Feng; Tang, Lu; Sun, Tianyi; Ren, Zhifeng; Huang, Yi; Boriskina, Svetlana V; Chen, Gang

    2016-01-01

    The promising quad-band solar spectral splitter incorporates the properties of the optical filter and the spectrally selective solar thermal absorber can direct PV band to PV modules and absorb thermal band energy for thermal process with low thermal losses. It provides a new strategy for spectral splitting and offers potential ways for hybrid PVT system design.

  15. SSBUV middle ultraviolet solar spectral irradiance measurements

    Science.gov (United States)

    Cebula, Richard P.; Hilsenrath, Ernest

    1994-01-01

    The Shuttle Solar Backscatter Ultraviolet (SSBUV) instrument performs multiple solar spectral irradiance measurements in the wavelength region 200 to 400 nm at 1.1 nm resolution during yearly Space Shuttle flights. Solar spectral irradiance observations from the first three SSBUV Shuttle flights, October 1989, October 1990, and August 1991, are compared with one another and with solar measurements made by the NOAA-11 SBUV/2 instrument. The repeated SSBUV solar spectral observations, which agree to within plus or minus 1-2 percent from 200 to 400 nm, are valuable not only as a means of validating and calibrating the satellite-based solar irradiance measurements, but also as a distinct set of stand-alone solar measurements for monitoring long-term changes in the solar spectral irradiance, which are important for ozone photochemistry.

  16. UARS Solar Ultraviolet Spectral Irradiance Monitor (SUSIM) Level 3BS V022 (UARSU3BS) at GES DISC

    Data.gov (United States)

    National Aeronautics and Space Administration — The Solar Ultraviolet Spectral Irradiance Monitor (SUSIM) Level 3BS data product consists of daily, 1 nm resolution, solar spectral irradiances and selected solar...

  17. Spectrally-Selective Photonic Structures for PV Applications

    Directory of Open Access Journals (Sweden)

    Benedikt Bläsi

    2010-01-01

    Full Text Available We review several examples of how spectrally-selective photonic structures may be used to improve solar cell systems. Firstly, we introduce different spectrally-selective structures that are based on interference effects. Examples shown include Rugate filter, edge filter and 3D photonic crystals such as artificial opals. In the second part, we discuss several examples of photovoltaic (PV concepts that utilize spectral selectivity such as fluorescence collectors, upconversion systems, spectrum splitting concepts and the intermediate reflector concept. The potential of spectrally selective filters in the context of solar cells is discussed.

  18. Spectral converters and luminescent solar concentrators

    Energy Technology Data Exchange (ETDEWEB)

    Scudo, Petra F.; Abbondanza, Luigi; Fusco, Roberto; Caccianotti, Luciano [Eni S.p.A, Research Center for Non-Conventional Energies - Istituto ENI Donegani, Via G.Fauser 4, 28100 Novara (Italy)

    2010-07-15

    In this paper we present a comprehensive theoretical description of molecular spectral converters in the specific context of luminescent solar concentrators (LSCs). The theoretical model is an extension to a three-level system interacting with a solar radiation bath of the standard quantum theory of atomic radiative processes. We derive the equilibrium equations of the conversion process and provide specific examples of application of this principle to the development of solar concentration devices. (author)

  19. Solar spectral irradiance changes during cycle 24

    Energy Technology Data Exchange (ETDEWEB)

    Marchenko, S. V.; DeLand, M. T. [Also at NASA/Goddard Space Flight Center, Greenbelt, MD, USA. (United States)

    2014-07-10

    We use solar spectra obtained by the Ozone Monitoring Instrument (OMI) on board the Aura satellite to detect and follow long-term (years) and short-term (weeks) changes in the solar spectral irradiance (SSI) in the 265-500 nm spectral range. During solar Cycle 24, in the relatively line-free regions the SSI changed by ∼0.6% ± 0.2% around 265 nm. These changes gradually diminish to 0.15% ± 0.20% at 500 nm. All strong spectral lines and blends, with the notable exception of the upper Balmer lines, vary in unison with the solar 'continuum'. Besides the lines with strong chromospheric components, the most involved species include Fe I blends and all prominent CH, NH, and CN spectral bands. Following the general trend seen in the solar 'continuum', the variability of spectral lines also decreases toward longer wavelengths. The long-term solar cycle SSI changes are closely, to within the quoted 0.1%-0.2% uncertainties, matched by the appropriately adjusted short-term SSI variations derived from the 27 day rotational modulation cycles. This further strengthens and broadens the prevailing notion about the general scalability of the UV SSI variability to the emissivity changes in the Mg II 280 nm doublet on timescales from weeks to years. We also detect subtle deviations from this general rule: the prominent spectral lines and blends at λ ≳ 350 nm show slightly more pronounced 27 day SSI changes when compared to the long-term (years) trends. We merge the solar data from Cycle 21 with the current Cycle 24 OMI and GOME-2 observations and provide normalized SSI variations for the 170-795 nm spectral region.

  20. High efficiency direct thermal to electric energy conversion from radioisotope decay using selective emitters and spectrally tuned solar cells

    Science.gov (United States)

    Chubb, Donald L.; Flood, Dennis J.; Lowe, Roland A.

    1993-01-01

    Thermophotovoltaic (TPV) systems are attractive possibilities for direct thermal-to-electric energy conversion, but have typically required the use of black body radiators operating at high temperatures. Recent advances in both the understanding and performance of solid rare-earth oxide selective emitters make possible the use of TPV at temperatures as low as 1200K. Both selective emitter and filter system TPV systems are feasible. However, requirements on the filter system are severe in order to attain high efficiency. A thin-film of a rare-earth oxide is one method for producing an efficient, rugged selective emitter. An efficiency of 0.14 and power density of 9.2 W/KG at 1200K is calculated for a hypothetical thin-film neodymia (Nd2O3) selective emitter TPV system that uses radioisotope decay as the thermal energy source.

  1. Spectral signature selection for mapping unvegetated soils

    Science.gov (United States)

    May, G. A.; Petersen, G. W.

    1975-01-01

    Airborne multispectral scanner data covering the wavelength interval from 0.40-2.60 microns were collected at an altitude of 1000 m above the terrain in southeastern Pennsylvania. Uniform training areas were selected within three sites from this flightline. Soil samples were collected from each site and a procedure developed to allow assignment of scan line and element number from the multispectral scanner data to each sampling location. These soil samples were analyzed on a spectrophotometer and laboratory spectral signatures were derived. After correcting for solar radiation and atmospheric attenuation, the laboratory signatures were compared to the spectral signatures derived from these same soils using multispectral scanner data. Both signatures were used in supervised and unsupervised classification routines. Computer-generated maps using the laboratory and multispectral scanner derived signatures resulted in maps that were similar to maps resulting from field surveys. Approximately 90% agreement was obtained between classification maps produced using multispectral scanner derived signatures and laboratory derived signatures.

  2. Spectrally Selective Materials For Architectural and Photo-thermal ...

    African Journals Online (AJOL)

    The concept of spectal selectivity of solar radiation is discussed with reference to its application in architecture and photothermal uses. A brief account of spectrally selective materials being investigated presently is also given. UNISWA Research Journal of Agriculture, Science and Technology Vol. 4 (1) 2000: pp 5-9 ...

  3. Influence of solvents on properties of solar selective coatings

    Indian Academy of Sciences (India)

    Solar selective coatings for solar thermal flat-plate collectors consisting of crystalline copper oxides and amorphous nickel oxide composites were obtained by robotic spray pyrolyzed deposition. The parameters were optimized for increased spectral selectivity (): high solar absorptance and low thermal emittance.

  4. Influence of solvents on properties of solar selective coatings ...

    Indian Academy of Sciences (India)

    Abstract. Solar selective coatings for solar thermal flat-plate collectors consisting of crystalline copper oxides and amorphous nickel oxide composites were obtained by robotic spray pyrolyzed deposition. The parameters were opti- mized for increased spectral selectivity (S): high solar absorptance and low thermal ...

  5. Influence of solvents on properties of solar selective coatings ...

    Indian Academy of Sciences (India)

    Solar selective coatings for solar thermal flat-plate collectors consisting of crystalline copper oxides and amorphous nickel oxide composites were obtained by robotic spray pyrolyzed deposition. The parameters were optimized for increased spectral selectivity (): high solar absorptance and low thermal emittance.

  6. Spectral Feature Selection for Data Mining

    CERN Document Server

    Zhao, Zheng Alan

    2011-01-01

    Spectral Feature Selection for Data Mining introduces a novel feature selection technique that establishes a general platform for studying existing feature selection algorithms and developing new algorithms for emerging problems in real-world applications. This technique represents a unified framework for supervised, unsupervised, and semisupervised feature selection. The book explores the latest research achievements, sheds light on new research directions, and stimulates readers to make the next creative breakthroughs. It presents the intrinsic ideas behind spectral feature selection, its th

  7. New observation strategies for the solar UV spectral irradiance

    Directory of Open Access Journals (Sweden)

    Kretzschmar Matthieu

    2012-09-01

    Full Text Available Many applications in space weather and in space situational awareness require continuous solar spectral irradiance measurements in the UV, and to a lesser degree in the visible band. Most space-borne solar radiometers are made out of two different parts: (i a front filter that selects the passband and (ii a detector that is usually based on silicon technology. Both are prone to degradation, which may be caused either by the degradation of the filter coating due to local deposition or to structural changes, or by the degradation of the silicon detector by solar radiative and energetic particle fluxes. In this study, we provide a theoretical analysis of the filter degradation that is caused by structural changes such as pinholes; contamination-induced degradation will not be considered. We then propose a new instrumental concept, which is expected to overcome, at least partially, these problems. We show how most of the solar UV spectrum can be reconstructed from the measurement of only five spectral bands. This instrumental concept outperforms present spectrometers in terms of degradation. This new concept in addition overcomes the need for silicon-based detectors, which are replaced by wide band gap material detectors. Front filters, which can contribute to in-flight degradation, therefore are not required, except for the extreme-UV (EUV range. With a small weight and a low telemetry, this concept may also have applications in solar physics, in astrophysics and in planetology.

  8. Solar spectral irradiance variability in cycle 24: observations and models

    Science.gov (United States)

    Marchenko, Sergey V.; DeLand, Matthew T.; Lean, Judith L.

    2016-12-01

    Utilizing the excellent stability of the Ozone Monitoring Instrument (OMI), we characterize both short-term (solar rotation) and long-term (solar cycle) changes of the solar spectral irradiance (SSI) between 265 and 500 nm during the ongoing cycle 24. We supplement the OMI data with concurrent observations from the Global Ozone Monitoring Experiment-2 (GOME-2) and Solar Radiation and Climate Experiment (SORCE) instruments and find fair-to-excellent, depending on wavelength, agreement among the observations, and predictions of the Naval Research Laboratory Solar Spectral Irradiance (NRLSSI2) and Spectral And Total Irradiance REconstruction for the Satellite era (SATIRE-S) models.

  9. Solar spectral irradiance variability in cycle 24: observations and models

    Directory of Open Access Journals (Sweden)

    Marchenko Sergey V.

    2016-01-01

    Full Text Available Utilizing the excellent stability of the Ozone Monitoring Instrument (OMI, we characterize both short-term (solar rotation and long-term (solar cycle changes of the solar spectral irradiance (SSI between 265 and 500 nm during the ongoing cycle 24. We supplement the OMI data with concurrent observations from the Global Ozone Monitoring Experiment-2 (GOME-2 and Solar Radiation and Climate Experiment (SORCE instruments and find fair-to-excellent, depending on wavelength, agreement among the observations, and predictions of the Naval Research Laboratory Solar Spectral Irradiance (NRLSSI2 and Spectral And Total Irradiance REconstruction for the Satellite era (SATIRE-S models.

  10. Fabrication of MWCNT/NiO nanocomposite thin films for optically selective solar absorbers

    CSIR Research Space (South Africa)

    Roro, Kittessa T

    2011-07-01

    Full Text Available This presentation explores solar thermal energy for harnessing solar energy for thermal energy (heat). Solar thermal collectors for water heating use a spectrally selective surface that absorb sunlight and convert it to heat. The presentation also...

  11. Spectral reflectance data of a high temperature stable solar selective coating based on MoSi2–Si3N4

    Directory of Open Access Journals (Sweden)

    D. Hernández-Pinilla

    2016-06-01

    Full Text Available Data of optical performance, thermal stability and ageing are given for solar selective coatings (SSC based on a novel MoSi2–Si3N4 absorbing composite. SSC have been prepared as multilayer stacks formed by silver as metallic infrared reflector, a double layer composite and an antireflective layer (doi: 10.1016/j.solmat.2016.04.001 [1]. Spectroscopic reflectance data corresponding to the optical performance of samples after moderate vacuum annealing at temperatures up to 600 °C and after ageing test of more than 200 h with several heating–cooling cycles are shown here.

  12. Calculation of the Performance of Solar Cells With Spectral Down Shifters Using Realistic Outdoor Solar Spectra

    NARCIS (Netherlands)

    van Sark, W.G.J.H.M.

    2007-01-01

    Spectral down converters and shifters have been proposed as a good means to enhance the efficiency of underlying solar cells. In this paper, we focus on the simulation of the outdoor performance of solar cells with spectral down shifters, i.e., multicrystalline silicon solar cells with semiconductor

  13. Spectral light management for solar energy conversion systems

    Science.gov (United States)

    Stanley, Cameron; Mojiri, Ahmad; Rosengarten, Gary

    2016-06-01

    Due to the inherent broadband nature of the solar radiation, combined with the narrow spectral sensitivity range of direct solar to electricity devices, there is a massive opportunity to manipulate the solar spectrum to increase the functionality and efficiency of solar energy conversion devices. Spectral splitting or manipulation facilitates the efficient combination of both high-temperature solar thermal systems, which can absorb over the entire solar spectrum to create heat, and photovoltaic cells, which only convert a range of wavelengths to electricity. It has only recently been possible, with the development of nanofabrication techniques, to integrate micro- and nano-photonic structures as spectrum splitters/manipulators into solar energy conversion devices. In this paper, we summarize the recent developments in beam splitting techniques, and highlight some relevant applications including combined PV-thermal collectors and efficient algae production, and suggest paths for future development in this field.

  14. Spectral light management for solar energy conversion systems

    Directory of Open Access Journals (Sweden)

    Stanley Cameron

    2016-06-01

    Full Text Available Due to the inherent broadband nature of the solar radiation, combined with the narrow spectral sensitivity range of direct solar to electricity devices, there is a massive opportunity to manipulate the solar spectrum to increase the functionality and efficiency of solar energy conversion devices. Spectral splitting or manipulation facilitates the efficient combination of both high-temperature solar thermal systems, which can absorb over the entire solar spectrum to create heat, and photovoltaic cells, which only convert a range of wavelengths to electricity. It has only recently been possible, with the development of nanofabrication techniques, to integrate micro- and nano-photonic structures as spectrum splitters/manipulators into solar energy conversion devices. In this paper, we summarize the recent developments in beam splitting techniques, and highlight some relevant applications including combined PV-thermal collectors and efficient algae production, and suggest paths for future development in this field.

  15. Flash spectral imaging for optical metrology of solar cells

    Science.gov (United States)

    Ho, Jian Wei; Koh, Jessica Li Jian; Wong, Johnson Kai Chi; Raj, Samuel; Janssen, Eric; Aberle, Armin G.

    2017-08-01

    Flash spectral imaging of full area (156 mm by 156 mm) silicon solar wafers and cells is realized in a setup integrating pseudo-monochromatic LEDs over the wavelength range of 370 to 1050 nm and a high-resolution monochrome camera. The captured information allows the computation of sample reflectance as a function of wavelength and coordinates, thereby constituting a spectral reflectance map. The derived values match that obtained from monochromator-based measurements. Optical inspection is then based on the characteristic reflectance of surface features at optimally contrasting wavelengths. The technique reveals otherwise hidden stains and anti-reflection coating (ARC) non-uniformities, and enable more selective visualization of grains in multicrystalline Si wafers. Optical contrast enhancement of metallization significantly improves accuracy of metal detection. The high effective resolution of the monochrome camera also allows fine metallization patterns to be measured. The rapid succession of flash-and-image-capture at each wavelength makes the reported optical metrology technique amenable in photovoltaic manufacturing for solar wafers/cells sorting, monitoring and optimization of processes.

  16. Simulating performance of solar cells with spectral downshifting layers

    NARCIS (Netherlands)

    van Sark, W.G.J.H.M.

    2008-01-01

    In order to estimate the performance of solar cells with downshifters under realistic irradiation conditions we used spectral distributions as they may be found outdoors. The spectral distributions were generated on a minutely basis by means of the spectrum simulation model SEDES2, using minutely

  17. Modelling rotational and cyclical spectral solar irradiance variations

    Science.gov (United States)

    Unruh, Yvonne

    Solar irradiance changes are highly wavelength dependent: solar-cycle variations in the UV can be on the order of tens of percent, while changes in the visible are typically only of the order of one or two permille. With the launch of a number of instruments to measure spectral solar irradiance, we are now for a first time in a good position to explore the changing solar irradiance over a large range of wavelengths and to test our irradiance models as well as some of their underlying assumptions. I will introduce some of the current modelling approaches and present model-data comparisons, using the SATIRE irradiance model and SORCE/SIM measurements as an example. I will conclude by highlighting a number of outstanding questions regarding the modelling of spectral irradiance and current approaches to address these.

  18. Spectral response of a polycrystalline silicon solar cell

    International Nuclear Information System (INIS)

    Ba, B.; Kane, M.

    1994-10-01

    A theoretical study of the spectral response of a polycrystalline silicon n-p junction solar cell is presented. The case of a fibrously oriented grain structure, involving grain boundary recombination velocity and grain size effects is discussed. The contribution of the base region on the internal quantum efficiency Q int is computed for different grain sizes and grain boundary recombination velocities in order to examine their influence. Suggestions are also made for the determination of base diffusion length in polycrystalline silicon solar cells using the spectral response method. (author). 15 refs, 4 figs

  19. Lanthanide ions as spectral converters for solar cells

    NARCIS (Netherlands)

    van der Ende, B.M.; Aarts, L.; Meijerink, A.

    2009-01-01

    The use of lanthanide ions to convert photons to different, more useful, wavelengths is well-known from a wide range of applications (e.g. fluorescent tubes, lasers, white light LEDs). Recently, a new potential application has emerged: the use of lanthanide ions for spectral conversion in solar

  20. High temperature solar selective coatings

    Science.gov (United States)

    Kennedy, Cheryl E

    2014-11-25

    Improved solar collectors (40) comprising glass tubing (42) attached to bellows (44) by airtight seals (56) enclose solar absorber tubes (50) inside an annular evacuated space (54. The exterior surfaces of the solar absorber tubes (50) are coated with improved solar selective coatings {48} which provide higher absorbance, lower emittance and resistance to atmospheric oxidation at elevated temperatures. The coatings are multilayered structures comprising solar absorbent layers (26) applied to the meta surface of the absorber tubes (50), typically stainless steel, topped with antireflective Savers (28) comprising at least two layers 30, 32) of refractory metal or metalloid oxides (such as titania and silica) with substantially differing indices of refraction in adjacent layers. Optionally, at least one layer of a noble metal such as platinum can be included between some of the layers. The absorbent layers cars include cermet materials comprising particles of metal compounds is a matrix, which can contain oxides of refractory metals or metalloids such as silicon. Reflective layers within the coating layers can comprise refractory metal silicides and related compounds characterized by the formulas TiSi. Ti.sub.3SiC.sub.2, TiAlSi, TiAN and similar compounds for Zr and Hf. The titania can be characterized by the formulas TiO.sub.2, Ti.sub.3O.sub.5. TiOx or TiO.sub.xN.sub.1-x with x 0 to 1. The silica can be at least one of SiO.sub.2, SiO.sub.2x or SiO.sub.2xN.sub.1-x with x=0 to 1.

  1. Total and Spectral Solar Irradiance Sensor (TSIS) Project Overview

    Science.gov (United States)

    Carlisle, Candace; Wedge, Ronnice; Wu, Dong; Stello, Harry; Robinson, Renee

    2015-01-01

    The main objective of the Total and Spectral solar Irradiance Sensor (TSIS) is to acquire measurements to determine the direct and indirect effects of solar radiation on climate. TSIS total solar irradiance measurements will extend a 37-year long uninterrupted measurement record of incoming solar radiation, the dominant energy source driving the Earths climate and the most precise indicator of changes in the Suns energy output. TSIS solar spectral irradiance measurements will determine the regions of the Earths multi-layered atmosphere that are affected by solar variability, from which the solar forcing mechanisms causing changes in climate can be quantified. TSIS includes two instruments: the Total Irradiance Monitor (TIM) and the Spectral Irradiance Monitor (SIM), integrated into a single payload. The TSIS TIM and SIM instruments are upgraded versions of the two instruments that are flying on the Solar Radiation and Climate Experiment (SORCE) mission launched in January 2003. TSIS was originally planned for the nadir-pointing National Polar-orbiting Operational Environmental Satellite System (NPOESS) spacecraft. The TSIS instrument passed a Critical Design Review (CDR) for NPOESS in December 2009. In 2010, TSIS was re-planned for the Joint Polar Satellite System (JPSS) Polar Free Flyer (PFF). The TSIS TIM, SIM, and associated electronics were built, tested, and successfully completed pre-ship review as of December 2013.In early 2014, NOAA and NASA agreed to fly TSIS on the International Space Station (ISS). In the FY16 Presidents Budget, NASA assumes responsibility for the TSIS mission on ISS. The TSIS project includes requirements, interface, design, build and test of the TSIS payload, including an updated pointing system, for accommodation on the ISS. It takes advantage of the prior development of the TSIS sensors and electronics. The International Space Station (ISS) program contributions include launch services and robotic installation of the TSIS payload

  2. Discrete Spectral Local Measurement Method for Testing Solar Concentrators

    Directory of Open Access Journals (Sweden)

    Huifu Zhao

    2012-01-01

    Full Text Available In order to compensate for the inconvenience and instability of outdoor photovoltaic concentration test system which are caused by the weather changes, we design an indoor concentration test system with a large caliber and a high parallelism, and then verify its feasibility and scientificity. Furthermore, we propose a new concentration test method: the discrete spectral local measurement method. A two-stage Fresnel concentration system is selected as the test object. The indoor and the outdoor concentration experiments are compared. The results show that the outdoor concentration efficiency of the two-stage Fresnel concentration system is 85.56%, while the indoor is 85.45%. The two experimental results are so close that we can verify the scientificity and feasibility of the indoor concentration test system. The light divergence angle of the indoor concentration test system is 0.267° which also matches with sunlight divergence angle. The indoor concentration test system with large diameter (145 mm, simple structure, and low cost will have broad applications in solar concentration field.

  3. Solar Rotational Modulations of Spectral Irradiance and Correlations with the Variability of Total Solar Irradiance

    Science.gov (United States)

    Lee, Jae N.; Cahalan, Robert F.; Wu, Dong L.

    2016-01-01

    Aims: We characterize the solar rotational modulations of spectral solar irradiance (SSI) and compare them with the corresponding changes of total solar irradiance (TSI). Solar rotational modulations of TSI and SSI at wavelengths between 120 and 1600 nm are identified over one hundred Carrington rotational cycles during 2003-2013. Methods: The SORCE (Solar Radiation and Climate Experiment) and TIMED (Thermosphere Ionosphere Mesosphere Energetics and Dynamics)/SEE (Solar EUV Experiment) measured and SATIRE-S modeled solar irradiances are analyzed using the EEMD (Ensemble Empirical Mode Decomposition) method to determine the phase and amplitude of 27-day solar rotational variation in TSI and SSI. Results: The mode decomposition clearly identifies 27-day solar rotational variations in SSI between 120 and 1600 nm, and there is a robust wavelength dependence in the phase of the rotational mode relative to that of TSI. The rotational modes of visible (VIS) and near infrared (NIR) are in phase with the mode of TSI, but the phase of the rotational mode of ultraviolet (UV) exhibits differences from that of TSI. While it is questionable that the VIS to NIR portion of the solar spectrum has yet been observed with sufficient accuracy and precision to determine the 11-year solar cycle variations, the temporal variations over one hundred cycles of 27-day solar rotation, independent of the two solar cycles in which they are embedded, show distinct solar rotational modulations at each wavelength.

  4. Solar rotational modulations of spectral irradiance and correlations with the variability of total solar irradiance

    Directory of Open Access Journals (Sweden)

    Lee Jae N.

    2016-01-01

    Full Text Available Aims: We characterize the solar rotational modulations of spectral solar irradiance (SSI and compare them with the corresponding changes of total solar irradiance (TSI. Solar rotational modulations of TSI and SSI at wavelengths between 120 and 1600 nm are identified over one hundred Carrington rotational cycles during 2003–2013. Methods: The SORCE (Solar Radiation and Climate Experiment and TIMED (Thermosphere Ionosphere Mesosphere Energetics and Dynamics/SEE (Solar EUV Experiment measured and SATIRE-S modeled solar irradiances are analyzed using the EEMD (Ensemble Empirical Mode Decomposition method to determine the phase and amplitude of 27-day solar rotational variation in TSI and SSI. Results: The mode decomposition clearly identifies 27-day solar rotational variations in SSI between 120 and 1600 nm, and there is a robust wavelength dependence in the phase of the rotational mode relative to that of TSI. The rotational modes of visible (VIS and near infrared (NIR are in phase with the mode of TSI, but the phase of the rotational mode of ultraviolet (UV exhibits differences from that of TSI. While it is questionable that the VIS to NIR portion of the solar spectrum has yet been observed with sufficient accuracy and precision to determine the 11-year solar cycle variations, the temporal variations over one hundred cycles of 27-day solar rotation, independent of the two solar cycles in which they are embedded, show distinct solar rotational modulations at each wavelength.

  5. Spectral variation of the solar radiation during an eclipse

    Directory of Open Access Journals (Sweden)

    Peter Koepke

    2001-05-01

    Full Text Available The time dependent variation of the spectral extraterrestrial solar flux is modelled for the conditions during a total eclipse. These data are used to calculate irradiance and actinic flux at the Earth’s surface for atmospheric conditions of August 11, 1999 at Weihenstephan. These results are compared with measurements. It is shown, that the spectral composition of solar radiation varies during the eclipse, since solar limb darkening has a spectral dependence. The solar radiation differs from that of a hypothetical sun without limb darkening by up to 30% in the near IR at 1500 nm and 60% in the UV-B at 310 nm. As shown by a comparison of modelling and measurements, this spectral variation has to be taken into account for modelling of UV radiative quantities in the atmosphere and resulting photochemical processes. The effect of broken cloudiness on irradiance and actinic flux and its dependency on wavelength and receiver geometry is explained. Der Verlauf der spektralen extraterrestrischen solaren Strahlung wÄhrend einer Sonnenfinsternis wurde berechnet. Basierend auf diesen Daten, unter BerÜcksichtigung der atmosphÄrischen Bedingungen am 11. August 1999 in Weihenstephan, wurden Globalstrahlung und Aktinischer Fluss am Boden modelliert und mit Messwerten verglichen. Die spektrale Zusammensetzung der Strahlung Ändert sich wÄhrend einer Sonnenfinsternis, bedingt durch die wellenlÄngenabhÄngige Randverdunklung der Sonne. Im Vergleich zu einer hypothetischen Sonne ohne Randverdunklung ist die solare Strahlung im nahen IR um bis zu 30% gemindert und im UVB bei 310 nm um bis zu 60%. Diese spektralen Änderungen sollten bei der Modellierung von Strahlung, z.B. fÜr photochemische Prozesse berÜcksichtigt werden. Dies wurde durch Messung und Modellierung gezeigt. Der Einfluss von Wolken auf gemessene Werte von Globalstrahlung und Aktinischem Fluss wurde untersucht und erklÄrt.

  6. NESSY: NLTE spectral synthesis code for solar and stellar atmospheres

    Science.gov (United States)

    Tagirov, R. V.; Shapiro, A. I.; Schmutz, W.

    2017-07-01

    Context. Physics-based models of solar and stellar magnetically-driven variability are based on the calculation of synthetic spectra for various surface magnetic features as well as quiet regions, which are a function of their position on the solar or stellar disc. Such calculations are performed with radiative transfer codes tailored for modeling broad spectral intervals. Aims: We aim to present the NLTE Spectral SYnthesis code (NESSY), which can be used for modeling of the entire (UV-visible-IR and radio) spectra of solar and stellar magnetic features and quiet regions. Methods: NESSY is a further development of the COde for Solar Irradiance (COSI), in which we have implemented an accelerated Λ-iteration (ALI) scheme for co-moving frame (CMF) line radiation transfer based on a new estimate of the local approximate Λ-operator. Results: We show that the new version of the code performs substantially faster than the previous one and yields a reliable calculation of the entire solar spectrum. This calculation is in a good agreement with the available observations.

  7. Spectral Trends of Solar Bursts at Sub-THz Frequencies

    Science.gov (United States)

    Fernandes, L. O. T.; Kaufmann, P.; Correia, E.; Giménez de Castro, C. G.; Kudaka, A. S.; Marun, A.; Pereyra, P.; Raulin, J.-P.; Valio, A. B. M.

    2017-01-01

    Previous sub-THz studies were derived from single-event observations. We here analyze for the first time spectral trends for a larger collection of sub-THz bursts. The collection consists of a set of 16 moderate to small impulsive solar radio bursts observed at 0.2 and 0.4 THz by the Solar Submillimeter-wave Telescope (SST) in 2012 - 2014 at El Leoncito, in the Argentinean Andes. The peak burst spectra included data from new solar patrol radio telescopes (45 and 90 GHz), and were completed with microwave data obtained by the Radio Solar Telescope Network, when available. We critically evaluate errors and uncertainties in sub-THz flux estimates caused by calibration techniques and the corrections for atmospheric transmission, and introduce a new method to obtain a uniform flux scale criterion for all events. The sub-THz bursts were searched during reported GOES soft X-ray events of class C or larger, for periods common to SST observations. Seven out of 16 events exhibit spectral maxima in the range 5 - 40 GHz with fluxes decaying at sub-THz frequencies (three of them associated to GOES class X, and four to class M). Nine out of 16 events exhibited the sub-THz spectral component. In five of these events, the sub-THz emission fluxes increased with a separate frequency from that of the microwave spectral component (two classified as X and three as M), and four events have only been detected at sub-THz frequencies (three classified as M and one as C). The results suggest that the THz component might be present throughout, with the minimum turnover frequency increasing as a function of the energy of the emitting electrons. The peculiar nature of many sub-THz burst events requires further investigations of bursts that are examined from SST observations alone to better understand these phenomena.

  8. Solar Cycle Spectral Irradiance Variation and Stratospheric Ozone

    Science.gov (United States)

    Stolarski, R. S.; Swartz, W. H.; Jackman, C. H.; Fleming, E. L.

    2011-12-01

    Recent measurements from the SIM instrument on the SORCE satellite have been interpreted by Harder et al (Geophys. Res. Lett., 36, L07801, doi:10.1029/2008GL036797, 2009) as implying a different spectral irradiance variation over the solar cycle than that put forward by Lean (Geophys. Res. Lett., 27, 2425-2428, 2000). When we inserted this new wavelength dependent solar cycle variation into our 3D CCM we found a different solar cycle dependence of the ozone concentration as a function of altitude from that we derived using the traditional Lean wavelength dependence. Examination of these results led us to realize that the main issue is the solar cycle variation of radiation at wavelengths less than 240 nm versus the solar cycle variation of radiation at wavelengths between 240 nm and 300 nm. The impact of wavelengths less than 240 nm occurs through photodissociation of O2 leading to the production of ozone. The impact of wavelengths between 240 nm and 300 nm occurs through photodissociation of O3 leading to an increase in O atoms and enhanced ozone destruction. Thus one wavelength region gives an in-phase relationship of ozone with the solar cycle while the other wavelength region gives an out-of-phase relationship of ozone with the solar cycle. We have used the Goddard two-dimensional (2D) photochemistry transport model to examine this relationship in more detail. We calculate the altitude and latitude sensitivity of ozone to changes in the solar UV irradiance as a function of wavelength. These results can be used to construct the ozone response to arbitrary wavelength dependencies of solar UV variation.

  9. Total and Spectral Solar Irradiance Sensor (TSIS) Project Status

    Science.gov (United States)

    Carlisle, Candace

    2018-01-01

    TSIS-1 studies the Sun's energy input to Earth and how solar variability affects climate. TSIS-1 will measure both the total amount of light that falls on Earth, known as the total solar irradiance (TSI), and how that light is distributed among ultraviolet, visible and infrared wavelengths, called solar spectral irradiance (SSI). TSIS-1 will provide the most accurate measurements of sunlight and continue the long-term climate data record. TSIS-1 includes two instruments: the Total Irradiance Monitor (TIM) and the Spectral Irradiance Monitor (SIM), integrated into a single payload on the International Space Station (ISS). The TSIS-1 TIM and SIM instruments are upgraded versions of the two instruments that are flying on the Solar Radiation and Climate Experiment (SORCE) mission launched in January 2003. NASA Goddard's TSIS project responsibilities include project management, system engineering, safety and mission assurance, and engineering oversight for TSIS-1. TSIS-1 was installed on the International Space Station in December 2017. At the end of the 90-day commissioning phase, responsibility for TSIS-1 operations transitions to the Earth Science Mission Operations (ESMO) project at Goddard for its 5-year operations. NASA contracts with the University of Colorado Laboratory for Atmospheric and Space Physics (LASP) for the design, development and testing of TSIS-1, support for ISS integration, science operations of the TSIS-1 instrument, data processing, data evaluation, calibration and delivery to the Goddard Earth Science Data and Information Services Center (GES DISC).

  10. Pulse Analysis Spectroradiometer System for Measuring the Spectral Distribution of Flash Solar Simulators: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Andreas, A. M.; Myers, D. R.

    2008-07-01

    Flashing artificial light sources are used extensively in photovoltaic module performance testing and plant production lines. There are several means of attempting to measure the spectral distribution of a flash of light; however, many of these approaches generally capture the entire pulse energy. We report here on the design and performance of a system to capture the waveform of flash at individual wavelengths of light. Any period within the flash duration can be selected, over which to integrate the flux intensity at each wavelength. The resulting spectral distribution is compared with the reference spectrum, resulting in a solar simulator classification.

  11. Spectral broadening of planetary radar signals by the solar wind

    International Nuclear Information System (INIS)

    Harmon, J.K.; Coles, W.A.

    1983-01-01

    The microturbulence spectrum of the solar wind is estimated using the spectral broadening of planetary radar signals. Observations were made with the two radars (12.6 cm and 70 cm) at Arecibo Observatory during the 1979 and 1981 superior conjunctions of Venus. These observations, which span the solar distance range of 5.4 to 25.5 R/sub sun/, are the first of their type to be reported. The data are consistent with earlier observations where comparisons can be made. The flattening of the high-frequency portion of the spectrum near the Sun reported by Woo and Armstrong is confirmed. In one case clear evidence for an inner scale in the vicinity of 2 km is found. Two transients, 1979 August 15 and 1981 April 24-25, with rather different characteristics were observed

  12. Solar spectral irradiance and summary outputs using excel.

    Science.gov (United States)

    Diffey, Brian

    2015-01-01

    The development of an Excel spreadsheet is described that calculates solar spectral irradiance between 290-3000 nm on an unshaded, horizontal surface under a cloudless sky at sea level, together with summary outputs such as global UV index, illuminance and percentage of energy in different wavebands. A deliberate goal of the project was to adopt the principle of Ockham's razor and to develop a model that is as simple as it can be commensurate with delivering results of adequate accuracy. Consequently, just four inputs are required-geographical latitude, month, day of month and time of day-resulting in a spreadsheet that is easily usable by anyone with an interest in sunlight and solar power irrespective of their background. The accuracy of the calculated data is sufficient for many applications where knowledge of the ultraviolet, visible and infrared levels in sunlight is of interest. © 2015 The American Society of Photobiology.

  13. Toward Improved Modeling of Spectral Solar Irradiance for Solar Energy Applications: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Xie, Yu [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Sengupta, Manajit [National Renewable Energy Laboratory (NREL), Golden, CO (United States)

    2017-10-19

    This study introduces the National Renewable Energy Laboratory's (NREL's) recent efforts to extend the capability of the Fast All-sky Radiation Model for Solar applications (FARMS) by computing spectral solar irradiances over both horizontal and inclined surfaces. A new model is developed by computing the optical thickness of the atmosphere using a spectral irradiance model for clear-sky conditions, SMARTS2. A comprehensive lookup table (LUT) of cloud bidirectional transmittance distribution functions (BTDFs) is precomputed for 2002 wavelength bands using an atmospheric radiative transfer model, libRadtran. The solar radiation transmitted through the atmosphere is given by considering all possible paths of photon transmission and the relevent scattering and absorption attenuation. Our results indicate that this new model has an accuracy that is similar to that of state-of-the-art radiative transfer models, but it is significantly more efficient.

  14. A Different View of Solar Spectral Irradiance Variations: Modeling Total Energy over Six-Month Intervals.

    Science.gov (United States)

    Woods, Thomas N; Snow, Martin; Harder, Jerald; Chapman, Gary; Cookson, Angela

    A different approach to studying solar spectral irradiance (SSI) variations, without the need for long-term (multi-year) instrument degradation corrections, is examining the total energy of the irradiance variation during 6-month periods. This duration is selected because a solar active region typically appears suddenly and then takes 5 to 7 months to decay and disperse back into the quiet-Sun network. The solar outburst energy, which is defined as the irradiance integrated over the 6-month period and thus includes the energy from all phases of active region evolution, could be considered the primary cause for the irradiance variations. Because solar cycle variation is the consequence of multiple active region outbursts, understanding the energy spectral variation may provide a reasonable estimate of the variations for the 11-year solar activity cycle. The moderate-term (6-month) variations from the Solar Radiation and Climate Experiment (SORCE) instruments can be decomposed into positive (in-phase with solar cycle) and negative (out-of-phase) contributions by modeling the variations using the San Fernando Observatory (SFO) facular excess and sunspot deficit proxies, respectively. These excess and deficit variations are fit over 6-month intervals every 2 months over the mission, and these fitted variations are then integrated over time for the 6-month energy. The dominant component indicates which wavelengths are in-phase and which are out-of-phase with solar activity. The results from this study indicate out-of-phase variations for the 1400 - 1600 nm range, with all other wavelengths having in-phase variations.

  15. Semiconductor-based Multilayer Selective Solar Absorber for Unconcentrated Solar Thermal Energy Conversion.

    Science.gov (United States)

    Thomas, Nathan H; Chen, Zhen; Fan, Shanhui; Minnich, Austin J

    2017-07-13

    Solar thermal energy conversion has attracted substantial renewed interest due to its applications in industrial heating, air conditioning, and electricity generation. Achieving stagnation temperatures exceeding 200 °C, pertinent to these technologies, with unconcentrated sunlight requires spectrally selective absorbers with exceptionally low emissivity in the thermal wavelength range and high visible absorptivity for the solar spectrum. In this Communication, we report a semiconductor-based multilayer selective absorber that exploits the sharp drop in optical absorption at the bandgap energy to achieve a measured absorptance of 76% at solar wavelengths and a low emittance of approximately 5% at thermal wavelengths. In field tests, we obtain a peak temperature of 225 °C, comparable to that achieved with state-of-the-art selective surfaces. With straightforward optimization to improve solar absorption, our work shows the potential for unconcentrated solar thermal systems to reach stagnation temperatures exceeding 300 °C, thereby eliminating the need for solar concentrators for mid-temperature solar applications such as supplying process heat.

  16. Spectral zone selection methodology for pebble bed reactors

    International Nuclear Information System (INIS)

    Mphahlele, Ramatsemela; Ougouag, Abderrafi M.; Ivanov, Kostadin N.; Gougar, Hans D.

    2011-01-01

    A methodology is developed for determining boundaries of spectral zones for pebble bed reactors. A spectral zone is defined as a region made up of a number of nodes whose characteristics are collectively similar and that are assigned the same few-group diffusion constants. The spectral zones are selected in such a manner that the difference (error) between the reference transport solution and the diffusion code solution takes a minimum value. This is achieved by choosing spectral zones through optimally minimizing this error. The objective function for the optimization algorithm is the total reaction rate error, which is defined as the sum of the leakage, absorption and fission reaction rates errors in each zone. The selection of these spectral zones is such that the core calculation results based on diffusion theory are within an acceptable tolerance as compared to a proper transport reference solution. Through this work, a consistent approach for identifying spectral zones that yield more accurate diffusion results is introduced.

  17. SORCE XPS Level 3 Solar Spectral Irradiance 6-Hour Means V010

    Data.gov (United States)

    National Aeronautics and Space Administration — The SORCE XUV Photometer System (XPS) Solar Spectral Irradiance (SSI) 6-Hour Data Product SOR3XPS6 contains solar XUV irradiances in the 0.1 to 27 nm range, as well...

  18. SORCE XPS Level 3 Solar Spectral Irradiance Daily Means V010

    Data.gov (United States)

    National Aeronautics and Space Administration — The SORCE XUV Photometer System (XPS) Solar Spectral Irradiance (SSI) Daily Data Product SOR3XPSD contains solar XUV irradiances in the 0.1 to 27 nm range, as well...

  19. Spectral mismatch and solar simulator quality factor in advanced LED solar simulators

    Science.gov (United States)

    Scherff, Maximilian L. D.; Nutter, Jason; Fuss-Kailuweit, Peter; Suthues, Jörn; Brammer, Torsten

    2017-08-01

    Solar cell simulators based on light emitting diodes (LED) have the potential to achieve a large potential market share in the next years. As advantages they can provide a short and long time stable spectrum, which fits very well to the global AM1.5g reference spectrum. This guarantees correct measurements during the flashes and throughout the light engines’ life span, respectively. Furthermore, a calibration with a solar cell type of different spectral response (SR) as well as the production of solar cells with varying SR in between two calibrations does not affect the correctness of the measurement result. A high quality 21 channel LED solar cell spectrum is compared to former study comprising a standard modified xenon spectrum light source. It is shown, that the spectrum of the 21-channel-LED light source performs best for all examined cases.

  20. Retrieving the solar EUV spectrum from a reduced set of spectral lines

    Directory of Open Access Journals (Sweden)

    T. D. de Wit

    2005-11-01

    Full Text Available The solar EUV irradiance is a key input for thermospheric and ionospheric models. Difficulties in continuously measuring the calibrated spectrum has prompted the use of various surrogate quantities. Although most proxies correlate quite well with the spectral variability, their use for modelling purposes becomes increasingly unsatisfactory. A different and data-driven approach is considered here, in which the EUV spectrum is reconstructed from a linear combination of a few, calibrated and carefully selected spectral lines. This approach is based on a statistical analysis of the temporal variability of EUV spectra, as recorded by the TIMED satellite. A basic set of lines is extracted, from which the salient features of the spectral variability can be reconstructed. The best results are achieved with a selection of 5 to 8 of these lines. This study focuses on the methodology for selecting these lines, which can also be used for instrument specification and provides new insight into the comparison of solar proxies against the EUV irradiance.

  1. Solar Spectral Irradiance Variability in Cycle 24: Model Predictions and OMI Observations

    Science.gov (United States)

    Marchenko, S.; DeLand, M.; Lean, J.

    2016-01-01

    Utilizing the excellent stability of the Ozone Monitoring Instrument (OMI), we characterize both short-term (solar rotation) and long-term (solar cycle) changes of the solar spectral irradiance (SSI) between 265-500 nanometers during the ongoing Cycle 24. We supplement the OMI data with concurrent observations from the GOME-2 (Global Ozone Monitoring Experiment - 2) and SORCE (Solar Radiation and Climate Experiment) instruments and find fair-to-excellent agreement between the observations and predictions of the NRLSSI2 (Naval Research Laboratory Solar Spectral Irradiance - post SORCE) and SATIRE-S (the Naval Research Laboratory's Spectral And Total Irradiance REconstruction for the Satellite era) models.

  2. Continuing the Total and Spectral Solar Irradiance Climate Data Record

    Science.gov (United States)

    Coddington, O.; Pilewskie, P.; Kopp, G.; Richard, E. C.; Sparn, T.; Woods, T. N.

    2017-12-01

    Radiative energy from the Sun establishes the basic climate of the Earth's surface and atmosphere and defines the terrestrial environment that supports all life on the planet. External solar variability on a wide range of scales ubiquitously affects the Earth system, and combines with internal forcings, including anthropogenic changes in greenhouse gases and aerosols, and natural modes such as ENSO, and volcanic forcing, to define past, present, and future climates. Understanding these effects requires continuous measurements of total and spectrally resolved solar irradiance that meet the stringent requirements of climate-quality accuracy and stability over time. The current uninterrupted 39-year total solar irradiance (TSI) climate data record is the result of several overlapping instruments flown on different missions. Measurement continuity, required to link successive instruments to the existing data record to discern long-term trends makes this important climate data record susceptible to loss in the event of a gap in measurements. While improvements in future instrument accuracy will reduce the risk of a gap, the 2017 launch of TSIS-1 ensures continuity of the solar irradiance record into the next decade. There are scientific and programmatic motivations for addressing the challenges of maintaining the solar irradiance data record beyond TSIS-1. The science rests on well-founded requirements of establishing a trusted climate observing network that can monitor trends in fundamental climate variables. Programmatically, the long-term monitoring of solar irradiance must be balanced within the broader goals of NASA Earth Science. New concepts for a low-risk, cost efficient observing strategy is a priority. New highly capable small spacecraft, low-cost launch vehicles and a multi-decadal plan to provide overlapping TSI and SSI data records are components of a low risk/high reliability plan with lower annual cost than past implementations. This paper provides the

  3. Solar Spectral Irradiance Variations in 240 - 1600 nm During the Recent Solar Cycles 21 - 23

    Science.gov (United States)

    Pagaran, J.; Weber, M.; Deland, M. T.; Floyd, L. E.; Burrows, J. P.

    2011-08-01

    Regular solar spectral irradiance (SSI) observations from space that simultaneously cover the UV, visible (vis), and the near-IR (NIR) spectral region began with SCIAMACHY aboard ENVISAT in August 2002. Up to now, these direct observations cover less than a decade. In order for these SSI measurements to be useful in assessing the role of the Sun in climate change, records covering more than an eleven-year solar cycle are required. By using our recently developed empirical SCIA proxy model, we reconstruct daily SSI values over several decades by using solar proxies scaled to short-term SCIAMACHY solar irradiance observations to describe decadal irradiance changes. These calculations are compared to existing solar data: the UV data from SUSIM/UARS, from the DeLand & Cebula satellite composite, and the SIP model (S2K+VUV2002); and UV-vis-IR data from the NRLSSI and SATIRE models, and SIM/SORCE measurements. The mean SSI of the latter models show good agreement (less than 5%) in the vis regions over three decades while larger disagreements (10 - 20%) are found in the UV and IR regions. Between minima and maxima of Solar Cycles 21, 22, and 23, the inferred SSI variability from the SCIA proxy is intermediate between SATIRE and NRLSSI in the UV. While the DeLand & Cebula composite provide the highest variability between solar minimum and maximum, the SIP/Solar2000 and NRLSSI models show minimum variability, which may be due to the use of a single proxy in the modeling of the irradiances. In the vis-IR spectral region, the SCIA proxy model reports lower values in the changes from solar maximum to minimum, which may be attributed to overestimations of the sunspot proxy used in modeling the SCIAMACHY irradiances. The fairly short timeseries of SIM/SORCE shows a steeper decreasing (increasing) trend in the UV (vis) than the other data during the descending phase of Solar Cycle 23. Though considered to be only provisional, the opposite trend seen in the visible SIM data

  4. Spectral and directional dependence of light-trapping in solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Ulbrich, Carolin

    2011-02-17

    This thesis investigates the directional and spectral dependence of light-incoupling and light-trapping in solar cells. The light-trapping does not notably change under increased angles of incidence. To enhance the incoupling at the front of the solar cell, the effects of a textured surface structure on the cover glass of the solar cell are investigated. The texture reduces the reflectance at the air-glass interface and, additionally, reduces the reflection losses originating at the interface between the glass and the transparent conductive oxide (TCO) as well as the TCO and the silicon (Si) absorber due to the randomization of light. On samples without a textured TCO/Si interface, the textured foil induces additional light-trapping in the photovoltaically active absorber material. This effect is not observed for samples with a textured TCO/Si interface. In this case, using tandem solar cells, a redistribution of light absorption in the top and bottom subcells is detected. The antireflective texture increases the short circuit current density in thin film silicon tandem solar cells by up to 1 mA/cm{sup 2}, and the conversion efficiency by up to 0.7 % absolute. The increase in the annual yield of solar cells is estimated to be up to 10 %. Further, the spectral dependence of the efficiency and annual yield of a tandem solar cell was investigated. The daily variation of the incident spectrum causes a change in the current matching of the serial connected subcells. Simulations determine the optimum subcell layer thicknesses of tandem solar cells. The thicknesses optimized in respect to the annual yield overlap in a wide range for both investigated locations with those for the AM1.5g standard spectrum. Though, a slight top limitation is favorable. Matching the short circuit currents of the subcells maximizes the overall current, but minimizes the fill factor. This thesis introduces a new definition for the matching condition of tandem solar cells. This definition

  5. Temperature Responses to Spectral Solar Variability on Decadal Time Scales

    Science.gov (United States)

    Cahalan, Robert F.; Wen, Guoyong; Harder, Jerald W.; Pilewskie, Peter

    2010-01-01

    Two scenarios of spectral solar forcing, namely Spectral Irradiance Monitor (SIM)-based out-of-phase variations and conventional in-phase variations, are input to a time-dependent radiative-convective model (RCM), and to the GISS modelE. Both scenarios and models give maximum temperature responses in the upper stratosphere, decreasing to the surface. Upper stratospheric peak-to-peak responses to out-of-phase forcing are approx.0.6 K and approx.0.9 K in RCM and modelE, approx.5 times larger than responses to in-phase forcing. Stratospheric responses are in-phase with TSI and UV variations, and resemble HALOE observed 11-year temperature variations. For in-phase forcing, ocean mixed layer response lags surface air response by approx.2 years, and is approx.0.06 K compared to approx.0.14 K for atmosphere. For out-of-phase forcing, lags are similar, but surface responses are significantly smaller. For both scenarios, modelE surface responses are less than 0.1 K in the tropics, and display similar patterns over oceanic regions, but complex responses over land.

  6. Spectral irradiance variations: comparison between observations and the SATIRE model on solar rotation time scales

    Science.gov (United States)

    Unruh, Y. C.; Krivova, N. A.; Solanki, S. K.; Harder, J. W.; Kopp, G.

    2008-07-01

    Aims: We test the reliability of the observed and calculated spectral irradiance variations between 200 and 1600 nm over a time span of three solar rotations in 2004. Methods: We compare our model calculations to spectral irradiance observations taken with SORCE/SIM, SoHO/VIRGO, and UARS/SUSIM. The calculations assume LTE and are based on the SATIRE (Spectral And Total Irradiance REconstruction) model. We analyse the variability as a function of wavelength and present time series in a number of selected wavelength regions covering the UV to the NIR. We also show the facular and spot contributions to the total calculated variability. Results: In most wavelength regions, the variability agrees well between all sets of observations and the model calculations. The model does particularly well between 400 and 1300 nm, but fails below 220 nm, as well as for some of the strong NUV lines. Our calculations clearly show the shift from faculae-dominated variability in the NUV to spot-dominated variability above approximately 400 nm. We also discuss some of the remaining problems, such as the low sensitivity of SUSIM and SORCE for wavelengths between approximately 310 and 350 nm, where currently the model calculations still provide the best estimates of solar variability.

  7. Outdoor spectral solar radiation variations and their relationship to photovoltaic device performance

    International Nuclear Information System (INIS)

    Riordan, C.; Hulstrom, R.

    1990-01-01

    Every photovoltaic device (PV cell or module) has a characteristic response to light at different wavelengths (blue, green, red, near-infrared) called the spectral response of the device. When a PV device is operating outdoors in natural sunlight, it is responding to incident light of different wavelengths from the sun, or spectral solar radiation. To optimize the response of a PC device to outdoor conditions and to understand its performance, one must characterize the spectral content of the incident solar radiation. In this paper, the authors describe the nature of spectral solar radiation, how and why it varies, and how this variation impacts on the performance of a PV device. The authors identify techniques and data that are available or needed to study the sensitivity of PV device performance to variations in spectral solar radiation and conclude with current areas of investigation

  8. Application of digital micromirror devices for spectral-response characterization of solar cells and photovoltaics

    Science.gov (United States)

    Fong, Alexandre Y.

    2010-02-01

    A key parameter in evaluating the performance of photovoltaic (PV) solar cells is characterization of electrical response to various incident source spectra. Conventional techniques utilize monochromators that emit single band-passes across a spectral region of interest. Since many solar cells respond differently at different broadband source light levels, a white bias light source that raises the overall light level to simulate the sun's broadband emission is typically introduced. However, such sources cannot render realistic solar continua. We present some initial results demonstrating how a spectrally-dispersed broadband source modulated with Texas Instruments' Digital Light Projection (DLP®) technology can be used to more faithfully synthesize solar spectra for this application.

  9. Solar Spectral Proxy Irradiance from GOES (SSPRING: a model for solar EUV irradiance

    Directory of Open Access Journals (Sweden)

    Suess Katherine

    2016-01-01

    Full Text Available Several currently operating instruments are able to measure the full EUV spectrum at sufficient wavelength resolution for use in upper-atmosphere modeling, the effects of space weather, and modeling satellite drag. However, no missions are planned at present to succeed the Thermosphere Ionosphere Mesosphere Energetics and Dynamics (TIMED and Solar Dynamics Observatory (SDO missions, which currently provide these data sources. To develop a suitable replacement for these measurements, we use two broadband EUV channels on the NOAA GOES satellites, the magnesium core-to-wing ratio (Mg II index from the SOlar Radiation and Climate Experiment (SORCE as well as EUV and Mg II time averages to model the EUV spectrum from 0.1 to 105 nm at 5-nm spectral resolution and daily time resolution. A Levenberg-Marquardt least squares fitting algorithm is used to determine a coefficient matrix that best reproduces a reference data set when multiplied by input data. The coefficient matrix is then applied to model data outside of the fitting interval. Three different fitting intervals are tested, with a variable fitting interval utilizing all days of data before the prediction date producing the best results. The correlation between the model results and the observed spectrum is found to be above 95% for the 0.1–50 nm range, and between 74% and 95% for the 50–105 nm range. We also find a favorable comparison between our results and the Flare Irradiance Spectral Model (FISM. These results provide a promising potential source for an empirical EUV spectral model after direct EUV measurements are no longer available, and utilize a similar EUV modeling technique as the upcoming GOES-R satellites.

  10. SORCE SOLSTICE FUV Level 3 Solar Spectral Irradiance Daily Means V013

    Data.gov (United States)

    National Aeronautics and Space Administration — The SORCE SOLSTICE Far-UV Solar Spectral Irradiance (SSI) data product SOR3SOLFUVD is constructed using measurements from the SOLSTICE FUV instrument, which are...

  11. NOAA Climate Data Record (CDR) of Solar Spectral Irradiance (SSI), NRLSSI Version 2

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This Climate Data Record (CDR) contains solar spectral irradiance (SSI) as a function of time and wavelength created with the Naval Research Laboratory model for...

  12. SAFARI 2000 Solar Spectral Flux Radiometer Data, Southern Africa, Dry Season 2000

    Data.gov (United States)

    National Aeronautics and Space Administration — ABSTRACT: The Solar Spectral Flux Radiometer (SSFR) was deployed on the University of Washington CV-580 during the dry season component of the Southern African...

  13. SORCE SIM Level 3 Solar Spectral Irradiance Daily Means V020

    Data.gov (United States)

    National Aeronautics and Space Administration — The SORCE SIM Solar Spectral Irradiance (SSI) data product SOR3SIMD is constructed using measurements from the SIM instruments, which are combined into merged daily...

  14. SORCE SIM Level 3 Solar Spectral Irradiance Daily Means V022

    Data.gov (United States)

    National Aeronautics and Space Administration — The SORCE SIM Solar Spectral Irradiance (SSI) data product SOR3SIMD is constructed using measurements from the SIM instruments, which are combined into merged daily...

  15. SORCE SOLSTICE MUV Level 3 Solar Spectral Irradiance Daily Means V012

    Data.gov (United States)

    National Aeronautics and Space Administration — The SORCE SOLSTICE Mid-UV Solar Spectral Irradiance (SSI) data product SOR3SOLMUVD is constructed using measurements from the SOLSTICE MUV instrument, which are...

  16. SORCE SOLSTICE FUV Level 3 Solar Spectral Irradiance Daily Means V012

    Data.gov (United States)

    National Aeronautics and Space Administration — The SORCE SOLSTICE Far-UV Solar Spectral Irradiance (SSI) data product SOR3SOLFUVD is constructed using measurements from the SOLSTICE FUV instrument, which are...

  17. SORCE SOLSTICE MUV Level 3 Solar Spectral Irradiance Daily Means V013

    Data.gov (United States)

    National Aeronautics and Space Administration — The SORCE SOLSTICE Mid-UV Solar Spectral Irradiance (SSI) data product SOR3SOLMUVD is constructed using measurements from the SOLSTICE MUV instrument, which are...

  18. SORCE SOLSTICE FUV Level 3 Solar Spectral Irradiance Daily Means V014

    Data.gov (United States)

    National Aeronautics and Space Administration — The SORCE SOLSTICE Far-UV Solar Spectral Irradiance (SSI) data product SOR3SOLFUVD is constructed using measurements from the SOLSTICE FUV instrument, which are...

  19. SAFARI 2000 Solar Spectral Flux Radiometer Data, Southern Africa, Dry Season 2000

    Data.gov (United States)

    National Aeronautics and Space Administration — The Solar Spectral Flux Radiometer (SSFR) was deployed on the University of Washington CV-580 during the dry season component of the Southern African Regional...

  20. Spectral band selection for classification of soil organic matter content

    Science.gov (United States)

    Henderson, Tracey L.; Szilagyi, Andrea; Baumgardner, Marion F.; Chen, Chih-Chien Thomas; Landgrebe, David A.

    1989-01-01

    This paper describes the spectral-band-selection (SBS) algorithm of Chen and Landgrebe (1987, 1988, and 1989) and uses the algorithm to classify the organic matter content in the earth's surface soil. The effectiveness of the algorithm was evaluated comparing the results of classification of the soil organic matter using SBS bands with those obtained using Landsat MSS bands and TM bands, showing that the algorithm was successful in finding important spectral bands for classification of organic matter content. Using the calculated bands, the probabilities of correct classification for climate-stratified data were found to range from 0.910 to 0.980.

  1. Convective blueshifts in the solar atmosphere. I. Absolute measurements with LARS of the spectral lines at 6302 Å

    Science.gov (United States)

    Löhner-Böttcher, J.; Schmidt, W.; Stief, F.; Steinmetz, T.; Holzwarth, R.

    2018-03-01

    Context. The solar convection manifests as granulation and intergranulation at the solar surface. In the photosphere, convective motions induce differential Doppler shifts to spectral lines. The observed convective blueshift varies across the solar disk. Aim. We focus on the impact of solar convection on the atmosphere and aim to resolve its velocity stratification in the photosphere. Methods: We performed high-resolution spectroscopic observations of the solar spectrum in the 6302 Å range with the Laser Absolute Reference Spectrograph at the Vacuum Tower Telescope. A laser frequency comb enabled the calibration of the spectra to an absolute wavelength scale with an accuracy of 1 m s-1. We systematically scanned the quiet Sun from the disk center to the limb at ten selected heliocentric positions. The analysis included 99 time sequences of up to 20 min in length. By means of ephemeris and reference corrections, we translated wavelength shifts into absolute line-of-sight velocities. A bisector analysis on the line profiles yielded the shapes and convective shifts of seven photospheric lines. Results: At the disk center, the bisector profiles of the iron lines feature a pronounced C-shape with maximum convective blueshifts of up to -450 m s-1 in the spectral line wings. Toward the solar limb, the bisectors change into a "\\"-shape with a saturation in the line core at a redshift of +100 m s-1. The center-to-limb variation of the line core velocities shows a slight increase in blueshift when departing the disk center for larger heliocentric angles. This increase in blueshift is more pronounced for the magnetically less active meridian than for the equator. Toward the solar limb, the blueshift decreases and can turn into a redshift. In general, weaker lines exhibit stronger blueshifts. Conclusions: Best spectroscopic measurements enabled the accurate determination of absolute convective shifts in the solar photosphere. We convolved the results to lower spectral

  2. Unsupervised Feature Selection via Nonnegative Spectral Analysis and Redundancy Control.

    Science.gov (United States)

    Li, Zechao; Tang, Jinhui

    2015-12-01

    In many image processing and pattern recognition problems, visual contents of images are currently described by high-dimensional features, which are often redundant and noisy. Toward this end, we propose a novel unsupervised feature selection scheme, namely, nonnegative spectral analysis with constrained redundancy, by jointly leveraging nonnegative spectral clustering and redundancy analysis. The proposed method can directly identify a discriminative subset of the most useful and redundancy-constrained features. Nonnegative spectral analysis is developed to learn more accurate cluster labels of the input images, during which the feature selection is performed simultaneously. The joint learning of the cluster labels and feature selection matrix enables to select the most discriminative features. Row-wise sparse models with a general ℓ(2, p)-norm (0 image benchmarks, including face data, handwritten digit data, and object image data. The proposed method achieves encouraging the experimental results in comparison with several representative algorithms, which demonstrates the effectiveness of the proposed algorithm for unsupervised feature selection.

  3. Relative spectral absorption of solar radiation by water vapor and cloud droplets

    Science.gov (United States)

    Davies, R.; Ridgway, W. L.

    1983-01-01

    A moderate (20/cm) spectral resolution model which accounts for both the highly variable spectral transmission of solar radiation through water vapor within and above cloud, as well as the more slowly varying features of absorption and anisotropic multiple scattering by the cloud droplets, is presented. Results from this model as applied to the case of a typical 1 km thick stratus cloud in a standard atmosphere, with cloud top altitude of 2 km and overhead sun, are discussed, showing the relative importance of water vapor above the cloud, water vapor within the cloud, and cloud droplets on the spectral absorption of solar radiation.

  4. Spectral selective fluorescence molecular imaging with volume holographic imaging system

    Directory of Open Access Journals (Sweden)

    Yanlu Lv

    2016-03-01

    Full Text Available A compact volume holographic imaging (VHI method that can detect fluorescence objects located in diffusive medium in spectral selective imaging manner is presented. The enlargement of lateral field of view of the VHI system is realized by using broadband illumination and demagnification optics. Each target spectrum of fluorescence emitting from a diffusive medium is probed by tuning the inclination angle of the transmission volume holographic grating (VHG. With the use of the single transmission VHG, fluorescence images with different spectrum are obtained sequentially and precise three-dimensional (3D information of deep fluorescent objects located in a diffusive medium can be reconstructed from these images. The results of phantom experiments demonstrate that two fluorescent objects with a sub-millimeter distance can be resolved by spectral selective imaging.

  5. Development of a Fast and Accurate PCRTM Radiative Transfer Model in the Solar Spectral Region

    Science.gov (United States)

    Liu, Xu; Yang, Qiguang; Li, Hui; Jin, Zhonghai; Wu, Wan; Kizer, Susan; Zhou, Daniel K.; Yang, Ping

    2016-01-01

    A fast and accurate principal component-based radiative transfer model in the solar spectral region (PCRTMSOLAR) has been developed. The algorithm is capable of simulating reflected solar spectra in both clear sky and cloudy atmospheric conditions. Multiple scattering of the solar beam by the multilayer clouds and aerosols are calculated using a discrete ordinate radiative transfer scheme. The PCRTM-SOLAR model can be trained to simulate top-of-atmosphere radiance or reflectance spectra with spectral resolution ranging from 1 cm(exp -1) resolution to a few nanometers. Broadband radiances or reflectance can also be calculated if desired. The current version of the PCRTM-SOLAR covers a spectral range from 300 to 2500 nm. The model is valid for solar zenith angles ranging from 0 to 80 deg, the instrument view zenith angles ranging from 0 to 70 deg, and the relative azimuthal angles ranging from 0 to 360 deg. Depending on the number of spectral channels, the speed of the current version of PCRTM-SOLAR is a few hundred to over one thousand times faster than the medium speed correlated-k option MODTRAN5. The absolute RMS error in channel radiance is smaller than 10(exp -3) mW/cm)exp 2)/sr/cm(exp -1) and the relative error is typically less than 0.2%.

  6. Influence of spectral solar radiation to the generating power of photovoltaic module; Taiyo denchi shutsuryoku eno taiyoko supekutoru eno eikyo

    Energy Technology Data Exchange (ETDEWEB)

    Minaki, S.; Ishihara, Y.; Todaka, T.; Harada, K. [Doshisha University, Kyoto (Japan); Oshiro, T.; Nakamura, H. [Japan quality Assurance Organization, Tokyo (Japan)

    1997-11-25

    As to the influence of spectral solar radiation to generating power of solar cells, a study was conducted from the aspects of season, time zone, intensity of solar radiation, etc. In the study, spectral responsive variation correction coefficients were introduced as evaluation values expressing the influence of spectral solar radiation. For the spectral distribution, an all sky spectral pyranometer by wavelength was used, and data were used which were obtained in the measurement in experimental facilities of the solar techno center. Concerning solar cell relative spectral sensitivity values, used were relative spectral sensitivity values of monocrystal and amorphous standard solar cells to the short-circuit current. Spectral response variation correction coefficients are coefficients correcting variations in conversion efficiency of solar cells due to changes in the spectral distribution. The changes of spectral responsive variation correction coefficients were studied using data obtained during April 1994 and March 1996. As a result, it was found that the coefficients showed large changes in summer and small ones in winter and that amorphous solar cells indicate this trend conspicuously. 3 refs., 6 figs., 3 tabs.

  7. Luminescent Spectral Conversion to Improve the Performance of Dye-Sensitized Solar Cells.

    Science.gov (United States)

    Hosseini, Zahra; Taghavinia, Nima; Wei-Guang Diau, Eric

    2017-12-06

    Relative to the broadband solar spectrum, a narrow range of spectral absorption of photovoltaic (PV) devices is considered an important determinant that the efficiency of light harvesting of these devices is less than unity. Having the narrowest spectral response to solar radiation among all PV devices, dye-sensitized solar cells (DSSCs) suffer severely from this loss. Luminescent spectral conversion provides a mechanism to manipulate and to adapt the incident solar spectrum by converting, through photoluminescence, the energies of solar photons into those that are more effectively captured by a PV device. This mechanism is particularly helpful for DSSCs because there is much flexibility in both the choice of the light-harvesting materials and the architecture of the DSSC. Here we review and discuss recent advances in the field of luminescent spectral conversion for DSSCs. The focus is on the architectural design of DSSCs, and the complications, advantages and new functionalities offered by each of their configurations are discussed. The loss mechanisms are examined and important parameters governing the spectral conversion mechanism of a DSSC are introduced. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. Shuttle SBUV (SSBUV) Solar Spectral Irradiance V008

    Data.gov (United States)

    National Aeronautics and Space Administration — The Shuttle Solar Backscatter Ultraviolet (SSBUV) level-2 irradiance data are available for eight space shuttle missions flown between 1989 and 1996. SSBUV, a...

  9. SORCE XPS Level 3 Solar Spectral Irradiance 6-Hour Means V011 (SOR3XPS6) at GES DISC

    Data.gov (United States)

    National Aeronautics and Space Administration — The SORCE XUV Photometer System (XPS) Solar Spectral Irradiance (SSI) 6-Hour Data Product SOR3XPS6 contains solar extreme ultraviolet irradiances in the 0.1 to 27 nm...

  10. SORCE XPS Level 3 Solar Spectral Irradiance Daily Means V011 (SOR3XPSD) at GES DISC

    Data.gov (United States)

    National Aeronautics and Space Administration — The SORCE XUV Photometer System (XPS) Solar Spectral Irradiance (SSI) Daily Data Product SOR3XPSD contains solar extreme ultraviolet irradiances in the 0.1 to 27 nm...

  11. Studying the effect of spectral variations intensity of the incident solar radiation on the Si solar cells performance

    Directory of Open Access Journals (Sweden)

    Ahmed Elsayed Ghitas

    2012-12-01

    Full Text Available Solar spectral variation is important in characterization of photovoltaic devices. We present results of an experimental investigation of the effects of the daily spectral variation on the device performance of multicrystalline silicon photovoltaic module. The investigation concentrate on the analysis of outdoor solar spectral measurements carried out at 1 min intervals on clear sky days. Short circuit current and open circuit voltage have been measured to describe the module electrical performance. We have shown that the shift in the solar spectrum towards infrared has a negative impact on the device performance of the module. The spectral bands in the visible region contribute more to the short circuit current than the bands in the infrared region while the ultraviolet region contributes least. The quantitative effect of the spectral variation on the performance of the photovoltaic module is reflected on their respective device performance parameters. The decrease in the visible and the increase in infrared of the radiation spectra account for the decreased current collection and hence power of the module.

  12. Solar Spectral Irradiance Reconstruction over 9 Millennia from a Composite 14C and 10Be Series

    Science.gov (United States)

    Wu, C. J.; Usoskin, I. G.; Krivova, N.; Kovaltsov, G.; Solanki, S. K.

    2017-12-01

    The Sun is the main external energy source to the Earth and thus the knowledge of solar variability on different time scales is important for understanding the solar influence on the terrestrial atmosphere and climate. The overall energy input and its spectral distribution are described by the total (TSI) and spectral (SSI) solar irradiance, respectively. Direct measurements of the solar irradiance provide information on solar variability on the decadal and shorter time scales, while the sunspot number record covers four centuries. On yet longer time scales only indirect proxies can be used, such as the concentrations of the cosmogenic isotopes 10Be and 14C in terrestrial archives. These isotopes are produced in the terrestrial atmosphere by impinging cosmic rays, whose flux is modulated by solar activity. Therefore the isotope data retrieved from various natural archives around the globe show a very high degree of similarity reflecting changes in the solar activity. Nevertheless, significant short-term deviations can be observed due to the different geochemical production processes and local climatic conditions. We will present the newest TSI/SSI reconstruction over the last 9000 years based on a new consistent composite multi-isotope proxy series. The solar irradiance reconstruction reveals the global and robust pattern of solar variability in the past.

  13. Systematic wavelength selection for improved multivariate spectral analysis

    Science.gov (United States)

    Thomas, Edward V.; Robinson, Mark R.; Haaland, David M.

    1995-01-01

    Methods and apparatus for determining in a biological material one or more unknown values of at least one known characteristic (e.g. the concentration of an analyte such as glucose in blood or the concentration of one or more blood gas parameters) with a model based on a set of samples with known values of the known characteristics and a multivariate algorithm using several wavelength subsets. The method includes selecting multiple wavelength subsets, from the electromagnetic spectral region appropriate for determining the known characteristic, for use by an algorithm wherein the selection of wavelength subsets improves the model's fitness of the determination for the unknown values of the known characteristic. The selection process utilizes multivariate search methods that select both predictive and synergistic wavelengths within the range of wavelengths utilized. The fitness of the wavelength subsets is determined by the fitness function F=.function.(cost, performance). The method includes the steps of: (1) using one or more applications of a genetic algorithm to produce one or more count spectra, with multiple count spectra then combined to produce a combined count spectrum; (2) smoothing the count spectrum; (3) selecting a threshold count from a count spectrum to select these wavelength subsets which optimize the fitness function; and (4) eliminating a portion of the selected wavelength subsets. The determination of the unknown values can be made: (1) noninvasively and in vivo; (2) invasively and in vivo; or (3) in vitro.

  14. The temperature dependence of the spectral and efficiency behavior of Si solar cell under low concentrated solar radiation

    Energy Technology Data Exchange (ETDEWEB)

    Shaltout, M.A. Mosalam; Rahoma, U.A.; Sabry, M. [National Research Inst. of Astronomy and Geophysics, Cairo (Egypt); El-Nicklawy, M.M.; Hassan, A.F. [Helwan Univ., Physics Dept., Cairo (Egypt)

    2000-12-01

    Relative spectral response of monocrystalline silicon solar cell is measured at different cell temperatures. At room temperature, the spectral response is found to have its maximum peak in the infrared (IR) range (800-1100 nm). By increasing the cell temperature, modification in the shape of the spectral response is observed and a shift of the peak towards the IR part of the spectrum is found. This behavior is of special importance that the temperature of highly illuminated thin film coated solar cells will be elevated. Other cell parameters as maximum power, fill factor, and cell efficiency are also studied at five illumination levels, viz., 1154, 1329, 1740, 2812, and 4010 W/m{sup 2} and temperature ranging from -3 to 90degC. (Author)

  15. A solar radio dynamic spectrograph with flexible temporal-spectral resolution

    Science.gov (United States)

    Du, Qing-Fu; Chen, Lei; Zhao, Yue-Chang; Li, Xin; Zhou, Yan; Zhang, Jun-Rui; Yan, Fa-Bao; Feng, Shi-Wei; Li, Chuan-Yang; Chen, Yao

    2017-09-01

    Observation and research on solar radio emission have unique scientific values in solar and space physics and related space weather forecasting applications, since the observed spectral structures may carry important information about energetic electrons and underlying physical mechanisms. In this study, we present the design of a novel dynamic spectrograph that has been installed at the Chashan Solar Radio Observatory operated by the Laboratory for Radio Technologies, Institute of Space Sciences at Shandong University. The spectrograph is characterized by real-time storage of digitized radio intensity data in the time domain and its capability to perform off-line spectral analysis of the radio spectra. The analog signals received via antennas and amplified with a low-noise amplifier are converted into digital data at a speed reaching up to 32 k data points per millisecond. The digital data are then saved into a high-speed electronic disk for further off-line spectral analysis. Using different word lengths (1-32 k) and time cadences (5 ms-10 s) for off-line fast Fourier transform analysis, we can obtain the dynamic spectrum of a radio burst with different (user-defined) temporal (5 ms-10 s) and spectral (3 kHz˜320 kHz) resolutions. This enables great flexibility and convenience in data analysis of solar radio bursts, especially when some specific fine spectral structures are under study.

  16. Towards Efficient Spectral Converters through Materials Design for Luminescent Solar Devices.

    Science.gov (United States)

    McKenna, Barry; Evans, Rachel C

    2017-07-01

    Single-junction photovoltaic devices exhibit a bottleneck in their efficiency due to incomplete or inefficient harvesting of photons in the low- or high-energy regions of the solar spectrum. Spectral converters can be used to convert solar photons into energies that are more effectively captured by the photovoltaic device through a photoluminescence process. Here, recent advances in the fields of luminescent solar concentration, luminescent downshifting, and upconversion are discussed. The focus is specifically on the role that materials science has to play in overcoming barriers in the optical performance in all spectral converters and on their successful integration with both established (e.g., c-Si, GaAs) and emerging (perovskite, organic, dye-sensitized) cell types. Current challenges and emerging research directions, which need to be addressed for the development of next-generation luminescent solar devices, are also discussed. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. Spectral analysis of turbulence propagation mechanisms in solar wind and tokamaks plasmas

    International Nuclear Information System (INIS)

    Dong, Yue

    2014-01-01

    This thesis takes part in the study of spectral transfers in the turbulence of magnetized plasmas. We will be interested in turbulence in solar wind and tokamaks. Spacecraft measures, first principle simulations and simple dynamical systems will be used to understand the mechanisms behind spectral anisotropy and spectral transfers in these plasmas. The first part of this manuscript will introduce the common context of solar wind and tokamaks, what is specific to each of them and present some notions needed to understand the work presented here. The second part deals with turbulence in the solar wind. We will present first an observational study on the spectral variability of solar wind turbulence. Starting from the study of Grappin et al. (1990, 1991) on Helios mission data, we bring a new analysis taking into account a correct evaluation of large scale spectral break, provided by the higher frequency data of the Wind mission. This considerably modifies the result on the spectral index distribution of the magnetic and kinetic energy. A second observational study is presented on solar wind turbulence anisotropy using autocorrelation functions. Following the work of Matthaeus et al. (1990); Dasso et al. (2005), we bring a new insight on this statistical, in particular the question of normalisation choices used to build the autocorrelation function, and its consequence on the measured anisotropy. This allows us to bring a new element in the debate on the measured anisotropy depending on the choice of the referential either based on local or global mean magnetic field. Finally, we study for the first time in 3D the effects of the transverse expansion of solar wind on its turbulence. This work is based on a theoretical and numerical scheme developed by Grappin et al. (1993); Grappin and Velli (1996), but never used in 3D. Our main results deal with the evolution of spectral and polarization anisotropy due to the competition between non-linear and linear (Alfven coupling

  18. Calculating spectral direct solar irradiance, diffuse and global in Heredia, Costa Rica

    International Nuclear Information System (INIS)

    Wright, Jaime

    2008-01-01

    A spectral model under conditions of clear skies has described the flow of solar irradiation and is verified experimentally in Heredia, Costa Rica. A description of the model is presented by comparing its results with experimental measurements. The model has calculated the spectral flows of the global solar irradiation, direct and diffuse incident on a horizontal surface. Necessary input data include latitude, altitude, surface albedo as characteristics of a locality, and atmospheric characteristics: turbidity, precipitable water vapor, total ozone content and the optical thickness of a particular subject. The results show satisfactory values. (author) [es

  19. Spectral line formation and oscillations in the solar chromosphere

    International Nuclear Information System (INIS)

    Gouttebroze, Pierre.

    1980-09-01

    This thesis is dedicated to two kind of models: the firsts, of semi-empiric type, seek to represent the vertical structure of the solar atmosphere and are treated in chapter II thru V. The others, of rather theoretical nature, have the ambition to simulate the oscillations of the chromosphere and are treated in chapter VI to X [fr

  20. Modeling Climate Responses to Spectral Solar Forcing on Centennial and Decadal Time Scales

    Science.gov (United States)

    Wen, G.; Cahalan, R.; Rind, D.; Jonas, J.; Pilewskie, P.; Harder, J.

    2012-01-01

    We report a series of experiments to explore clima responses to two types of solar spectral forcing on decadal and centennial time scales - one based on prior reconstructions, and another implied by recent observations from the SORCE (Solar Radiation and Climate Experiment) SIM (Spectral 1rradiance Monitor). We apply these forcings to the Goddard Institute for Space Studies (GISS) Global/Middle Atmosphere Model (GCMAM). that couples atmosphere with ocean, and has a model top near the mesopause, allowing us to examine the full response to the two solar forcing scenarios. We show different climate responses to the two solar forCing scenarios on decadal time scales and also trends on centennial time scales. Differences between solar maximum and solar minimum conditions are highlighted, including impacts of the time lagged reSponse of the lower atmosphere and ocean. This contrasts with studies that assume separate equilibrium conditions at solar maximum and minimum. We discuss model feedback mechanisms involved in the solar forced climate variations.

  1. Review of Mid- to High-Temperature Solar Selective Absorber Materials

    Energy Technology Data Exchange (ETDEWEB)

    Kennedy, C. E.

    2002-07-01

    This report describes the concentrating solar power (CSP) systems using solar absorbers to convert concentrated sunlight to thermal electric power. It is possible to achieve solar absorber surfaces for efficient photothermal conversion having high solar absorptance (a) for solar radiation and a low thermal emittance (e) at the operational temperature. A low reflectance (?'' 0) at wavelengths (?) 3 mm and a high reflectance (?'' 1) at l 3 mm characterize spectrally selective surfaces. The operational temperature ranges of these materials for solar applications can be categorized as low temperature (T< 100 C), mid-temperature (100 C< T< 400 C), and high-temperature (T> 400 C). High- and mid-temperature applications are needed for CSP applications. For CSP applications, the ideal spectrally selective surface would be low-cost and easy to manufacture, chemically and thermally stable in air at elevated operating temperatures (T= 500 C), and have a solar absorptance= 0.98 and a thermal emittance= 0.05 at 500 C.

  2. Spectral Analysis of Geomagnetic Activity Indices and Solar Wind Parameters

    Directory of Open Access Journals (Sweden)

    Jung-Hee Kim

    2014-06-01

    Full Text Available Solar variability is widely known to affect the interplanetary space and in turn the Earth’s electromagnetical environment on the basis of common periodicities in the solar and geomagnetic activity indices. The goal of this study is twofold. Firstly, we attempt to associate modes by comparing a temporal behavior of the power of geomagnetic activity parameters since it is barely sufficient searching for common peaks with a similar periodicity in order to causally correlate geomagnetic activity parameters. As a result of the wavelet transform analysis we are able to obtain information on the temporal behavior of the power in the velocity of the solar wind, the number density of protons in the solar wind, the AE index, the Dst index, the interplanetary magnetic field, B and its three components of the GSM coordinate system, BX, BY, BZ. Secondly, we also attempt to search for any signatures of influence on the space environment near the Earth by inner planets orbiting around the Sun. Our main findings are as follows: (1 Parameters we have investigated show periodicities of ~ 27 days, ~ 13.5 days, ~ 9 days. (2 The peaks in the power spectrum of BZ appear to be split due to an unknown agent. (3 For some modes powers are not present all the time and intervals showing high powers do not always coincide. (4 Noticeable peaks do not emerge at those frequencies corresponding to the synodic and/or sidereal periods of Mercury and Venus, which leads us to conclude that the Earth’s space environment is not subject to the shadow of the inner planets as suggested earlier.

  3. SPECTRAL AND SPATIAL SELECTIVITY OF LUMINANCE VISION IN REEF FISH

    Directory of Open Access Journals (Sweden)

    Ulrike E Siebeck

    2014-09-01

    Full Text Available Luminance vision has high spatial resolution and is used for form vision and texture discrimination. In humans, birds and bees luminance channel is spectrally selective – it depends on the signals of the long-wavelength sensitive photoreceptors (bees or on the sum of long- and middle- wavelength sensitive cones (humans, but not on the signal of the short-wavelength sensitive (blue photoreceptors. The reasons of such selectivity are not fully understood. The aim of this study is to reveal the inputs of cone signals to high resolution luminance vision in reef fish. 16 freshly caught damselfish, Pomacentrus amboinensis, were trained to discriminate stimuli differing either in their colour or in their fine patterns (stripes vs. cheques. Three colours (‘bright green’, ‘dark green’ and ‘blue’ were used to create two sets of colour and two sets of pattern stimuli. The ‘bright green’ and ‘dark green’ were similar in their chromatic properties for fish, but differed in their lightness; the ‘dark green’ differed from ‘blue’ in the signal for the blue cone, but yielded similar signals in the long-wavelength and middle-wavelength cones. Fish easily learned to discriminate ‘bright green’ from ‘dark green’ and ‘dark green’ from ‘blue’ stimuli. Fish also could discriminate the fine patterns created from ‘dark green’ and ‘bright green’. However, fish failed to discriminate fine patterns created from ‘blue’ and ‘dark green’ colours, i.e. the colours that provided contrast for the blue-sensitive photoreceptor, but not for the long-wavelength sensitive one. High resolution luminance vision in damselfish, Pomacentrus amboinensis, does not have input from the blue-sensitive cone, which may indicate that the spectral selectivity of luminance channel is a general feature of visual processing in both aquatic and terrestrial animals.

  4. Artifact Interpretation of Spectral Response Measurements on Two-Terminal Multijunction Solar Cells

    NARCIS (Netherlands)

    Si, F.T.; Isabella, O.; Zeman, M.

    2016-01-01

    Multijunction solar cells promise higher power-conversion efficiency than the single-junction. With respect to two-terminal devices, an accurate measurement of the spectral response requires a delicate adjustment of the light- and voltage-biasing; otherwise it can result in artifacts in the data and

  5. Colorful solar selective absorber integrated with different colored units.

    Science.gov (United States)

    Chen, Feiliang; Wang, Shao-Wei; Liu, Xingxing; Ji, Ruonan; Li, Zhifeng; Chen, Xiaoshuang; Chen, Yuwei; Lu, Wei

    2016-01-25

    Solar selective absorbers are the core part for solar thermal technologies such as solar water heaters, concentrated solar power, solar thermoelectric generators and solar thermophotovoltaics. Colorful solar selective absorber can provide new freedom and flexibility beyond energy performance, which will lead to wider utilization of solar technologies. In this work, we present a monolithic integration of colored solar absorber array with different colors on a single substrate based on a multilayered structure of Cu/TiN(x)O(y)/TiO(2)/Si(3)N(4)/SiO(2). A colored solar absorber array with 16 color units is demonstrated experimentally by using combinatorial deposition technique via changing the thickness of SiO(2) layer. The solar absorptivity and thermal emissivity of all the color units is higher than 92% and lower than 5.5%, respectively. The colored solar selective absorber array can have colorful appearance and designable patterns while keeping high energy performance at the same time. It is a new candidate for a number of solar applications, especially for architecture integration and military camouflage.

  6. Influence of the spectral distribution of a solar simulator and of the outer diffuse radiation in the estimation of the optical yield of a thermal solar receiver; Influencia de la distribucion espectral de un simulador solar y de la radiacion difusa exterior en la estimacion del rendimiento optico de un captador solar termico

    Energy Technology Data Exchange (ETDEWEB)

    Sallaberry, F.; Garcia de Jalon, A.; Ramirez, L.; Olano, X.; Bernad, I.; Erice, R.

    2008-07-01

    In this paper we will show the results of the analysis of factors that influence the estimation of optical efficiency of solar thermal collectors testes according to the European standard UNE-EN 12975-2. Indoor tests with solar simulator involve control of the spectrum of its lamps to ensure that the difference with the Sun one does not change the optical efficiency {eta}{sub 0} of the collector. For outdoor tests, the diffuse radiation should be control as well. In the laboratory (LCS) of CENER, solar collectors tests are done according to part 6.1 of the standard UNE{sub E}N 12975-2 in continuous solar simulator. This study estimated the spectral correction applied to the estimation of optical efficiency of some solar collectors, with different selective materials. Likewise, we will weight the influence of terms related to diffuse radiation and spectral distribution. (Author)

  7. Analysis of mass spectral serum profiles for biomarker selection.

    Science.gov (United States)

    Ressom, Habtom W; Varghese, Rency S; Abdel-Hamid, Mohamed; Eissa, Sohair Abdel-Latif; Saha, Daniel; Goldman, Lenka; Petricoin, Emanuel F; Conrads, Thomas P; Veenstra, Timothy D; Loffredo, Christopher A; Goldman, Radoslav

    2005-11-01

    Mass spectrometric profiles of peptides and proteins obtained by current technologies are characterized by complex spectra, high dimensionality and substantial noise. These characteristics generate challenges in the discovery of proteins and protein-profiles that distinguish disease states, e.g. cancer patients from healthy individuals. We present low-level methods for the processing of mass spectral data and a machine learning method that combines support vector machines, with particle swarm optimization for biomarker selection. The proposed method identified mass points that achieved high prediction accuracy in distinguishing liver cancer patients from healthy individuals in SELDI-QqTOF profiles of serum. MATLAB scripts to implement the methods described in this paper are available from the HWR's lab website http://lombardi.georgetown.edu/labpage

  8. Prediction of solar activity on the basis of spectral characteristics of sunspot number

    Directory of Open Access Journals (Sweden)

    E. Echer

    2004-06-01

    Full Text Available Prediction of solar activity strength for solar cycles 23 and 24 is performed on the basis of extrapolation of sunspot number spectral components. Sunspot number data during 1933-1996 periods (solar cycles 17-22 are searched for periodicities by iterative regression. The periods significant at the 95% confidence level were used in a sum of sine series to reconstruct sunspot series, to predict the strength of solar cycles 23 and 24. The maximum peak of solar cycles is adequately predicted (cycle 21: 158±13.2 against an observed peak of 155.4; cycle 22: 178<±13.2 against 157.6 observed. Solar cycle 23 was predicted to have a peak in 2000 with maximum amplitude of 125±13.2, in good agreement with the 119.6 observed. The minimum of solar cycle 23 is predicted to occur around 2007-2008. For solar cycle 24, the maximum is predicted to occur in 2012 (115±13.2 or 2013 (117±13.2 and this shall be a very weak solar cycle.

  9. Application of Satellite-Based Spectrally-Resolved Solar Radiation Data to PV Performance Studies

    Directory of Open Access Journals (Sweden)

    Ana Maria Gracia Amillo

    2015-04-01

    Full Text Available In recent years, satellite-based solar radiation data resolved in spectral bands have become available. This has for the first time made it possible to produce maps of the geographical variation in the solar spectrum. It also makes it possible to estimate the influence of these variations on the performance of photovoltaic (PV modules. Here, we present a study showing the magnitude of the spectral influence on PV performance over Europe and Africa. The method has been validated using measurements of a CdTe module in Ispra, Italy, showing that the method predicts the spectral influence to within ±2% on a monthly basis and 0.1% over a 19-month period. Application of the method to measured spectral responses of crystalline silicon, CdTe and single-junction amorphous silicon (a-Si modules shows that the spectral effect is smallest over desert areas for all module types, higher in temperate Europe and highest in tropical Africa, where CdTe modules would be expected to yield +6% and single- junction a-Si modules up to +10% more energy due to spectral effects. In contrast, the effect for crystalline silicon modules is less than ±1% in nearly all of Africa and Southern Europe, rising to +1% or +2% in Northern Europe.

  10. Enhancing solar cell efficiency: the search for luminescent materials as spectral converters.

    Science.gov (United States)

    Huang, Xiaoyong; Han, Sanyang; Huang, Wei; Liu, Xiaogang

    2013-01-07

    Photovoltaic (PV) technologies for solar energy conversion represent promising routes to green and renewable energy generation. Despite relevant PV technologies being available for more than half a century, the production of solar energy remains costly, largely owing to low power conversion efficiencies of solar cells. The main difficulty in improving the efficiency of PV energy conversion lies in the spectral mismatch between the energy distribution of photons in the incident solar spectrum and the bandgap of a semiconductor material. In recent years, luminescent materials, which are capable of converting a broad spectrum of light into photons of a particular wavelength, have been synthesized and used to minimize the losses in the solar-cell-based energy conversion process. In this review, we will survey recent progress in the development of spectral converters, with a particular emphasis on lanthanide-based upconversion, quantum-cutting and down-shifting materials, for PV applications. In addition, we will also present technical challenges that arise in developing cost-effective high-performance solar cells based on these luminescent materials.

  11. PROBING THE SOLAR ATMOSPHERE USING OSCILLATIONS OF INFRARED CO SPECTRAL LINES

    International Nuclear Information System (INIS)

    Penn, M. J.; Schad, T.; Cox, E.

    2011-01-01

    Oscillations were observed across the whole solar disk using the Doppler shift and line center intensity of spectral lines from the CO molecule near 4666 nm with the National Solar Observatory's McMath/Pierce solar telescope. Power, coherence, and phase spectra were examined, and diagnostic diagrams reveal power ridges at the solar global mode frequencies to show that these oscillations are solar p-modes. The phase was used to determine the height of formation of the CO lines by comparison with the IR continuum intensity phase shifts as measured in Kopp et al.; we find that the CO line formation height varies from 425 km μ > 0.5. The velocity power spectra show that while the sum of the background and p-mode power increases with height in the solar atmosphere as seen in previous work, the power in the p-modes only (background subtracted) decreases with height. The CO line center intensity weakens in regions of stronger magnetic fields, as does the p-mode oscillation power. Across most of the solar surface the phase shift is larger than the expected value of 90 0 for an adiabatic atmosphere. We fit the phase spectra at different disk positions with a simple atmospheric model to determine that the acoustic cutoff frequency is about 4.5 mHz with only small variations, but that the thermal relaxation frequency drops significantly from 2.7 to 0 mHz at these heights in the solar atmosphere.

  12. GISS GCMAM Modeled Climate Responses to Total and Spectral Solar Forcing on Decadal and Centennial Time Scales

    Science.gov (United States)

    Wen, G.; Cahalan, R. F.; Rind, D. H.; Jonas, J.; Pilewskie, P.; Harder, J. W.; Krivova, N.

    2014-12-01

    We examine the influence of the SORCE (Solar Radiation and Climate Experiment) SIM (Spectral Irradiance Monitor) observed spectral solar irradiance (SSI) variations on Earth's climate. We apply two reconstructed spectral solar forcing scenarios, one SIM based, the other based on the SATIRE (Spectral And Total Irradiance REconstruction) model, as inputs to the GISS (Goddard Institute for Space Studies) GCMAM (Global Climate Middle Atmosphere Model) to examine the climate responses on decadal and centennial time scales. We show that the atmosphere has different temperature, ozone, and dynamic responses to the two solar spectral forcing scenarios, even when the variations in TSI (Total Solar Irradiance) are the same. We find that solar variations under either scenario contribute a small fraction of the observed temperature increase since the industrial revolution. The trend of global averaged surface air temperature response to the SIM-based solar forcing is 0.02 °C/century, about half of the temperature trend to the SATIRE-based SSI. However the temporal variation of the surface air temperature for the SIM-based solar forcing scenario is much larger compared to its SATIRE counterpart. Further research is required to examine TSI and SSI variations in the ascending phase of solar cycle 24, to assess their implications for the solar influence on climate.

  13. The spectral appearance of solar-type collapsing protostellar clouds

    International Nuclear Information System (INIS)

    Bertout, C.; Yorke, H.W.

    1978-04-01

    In this paper, we review the spectral properties of collapsing protostellar clouds, based on radiative transfer computations in hydrodynamic protostar models. In the first section, the basic results of protostar evolution computations in spherically symmetric and axially symmetry geometries, as they pertain to the appearance of protostars, are briefly reviewed. In the second section, we discuss the continuum appearance of spherically symmetric protostars with various masses. Also, we present recent results for the continuum appearance of an axially symmetric protostellar cloud. The third section deals with the line formation problem and describes preliminary results for a OH molecule in an axially symmetric collapsing cloud. Then we review recent theoretical and observational results obtained for the last evolutionary phase of protostars, known as the YY Orionis phase, when the stellar core first becomes visible in the optical range. Some of the new results and conclusions presented here can be summarized as follows: Rotating collapsing clouds are in general less luminous and cooler than corresponding non-rotating clouds - due to the longer evolutionary time scale. Nevertheless, high resolution studies (resolution [de

  14. Spectral signature of ultraviolet solar irradiance in Zacatecas

    Energy Technology Data Exchange (ETDEWEB)

    Pinedo V, J. L; Mireles G, F; Rios M, C; Quirino T, L. L; Davila R, J. I [Universidad Autonoma de Zacatecas, Zacatecas, Zacatecas (Mexico)

    2006-10-15

    This study presents an analysis of the global ultraviolet spectral irradiance (290-400 nm) registered in Zacatecas, a city near the Tropic of Cancer, located at 2500 m above sea level, latitude of 22 degrees N and longitude of 102 degrees W. The spectra have been measured using a Bentham radiometer with a 0.5 nm step in wavelength. The measurements show relatively high levels of ultraviolet irradiance (UV), which may be characteristic of areas close to the Tropic of Cancer. Faced with an increase of the incidence of skin cancer among the population of Zacatecas, these measurements highlight that a damage prevention plan is required. [Spanish] En este trabajo se presenta un analisis de la radiacion espectral global ultravioleta (290-400 nm) registrada en Zacatecas, una ciudad vecina al tropico de cancer, situada a 2500 m sobre el nivel del mar, latitud de 22 grados N y longitud de 102 grados O. Los espectros correspondientes han sido medidos mediante un espectroradiometro Bentham con un paso de 0.5 nm de longitud de onda. Las mediciones muestran niveles de radiacion ultravioleta (UV) relativamente elevados, que pueden ser caracteristicos de las zonas vecinas al tropico de cancer. Frente al aumento de incidencia de cancer en la piel en la poblacion del estado de Zacatecas, estas mediciones ponen en relieve la necesidad de formular un plan preventivo de danos.

  15. Observed Variability of the Solar Mg II h Spectral Line

    Science.gov (United States)

    Schmit, D.; Bryans, P.; De Pontieu, B.; McIntosh, S.; Leenaarts, J.; Carlsson, M.

    2015-10-01

    The Mg ii h&k doublet are two of the primary spectral lines observed by the Sun-pointing Interface Region Imaging Spectrograph (IRIS). These lines are tracers of the magnetic and thermal environment that spans from the photosphere to the upper chromosphere. We use a double-Gaussian model to fit the Mg ii h profile for a full-Sun mosaic data set taken on 2014 August 24. We use the ensemble of high-quality profile fits to conduct a statistical study on the variability of the line profile as it relates the magnetic structure, dynamics, and center-to-limb viewing angle. The average internetwork profile contains a deeply reversed core and is weakly asymmetric at h2. In the internetwork, we find a strong correlation between h3 wavelength and profile asymmetry as well as h1 width and h2 width. The average reversal depth of the h3 core is inversely related to the magnetic field. Plage and sunspots exhibit many profiles that do not contain a reversal. These profiles also occur infrequently in the internetwork. We see indications of magnetically aligned structures in plage and network in statistics associated with the line core, but these structures are not clear or extended in the internetwork. The center-to-limb variations are compared to predictions of semi-empirical model atmospheres. We measure a pronounced limb darkening in the line core that is not predicted by the model. The aim of this work is to provide a comprehensive measurement baseline and preliminary analysis on the observed structure and formation of the Mg ii profiles observed by IRIS.

  16. Solar spectral irradiance variability of some chromospheric emission lines through the solar activity cycles 21-23

    Directory of Open Access Journals (Sweden)

    Göker Ü.D.

    2017-01-01

    Full Text Available A study of variations of solar spectral irradiance (SSI in the wave-length ranges 121.5 nm-300.5 nm for the period 1981-2009 is presented. We used various data for ultraviolet (UV spectral lines and international sunspot number (ISSN from interactive data centers such as SME (NSSDC, UARS (GDAAC, SORCE (LISIRD and SIDC, respectively. We reduced these data by using the MATLsoftware package. In this respect, we revealed negative correlations of intensities of UV (289.5 nm-300.5 nm spectral lines originating in the solar chromosphere with the ISSN index during the unusually prolonged minimum between the solar activity cycles (SACs 23 and 24. We also compared our results with the variations of solar activity indices obtained by the ground-based telescopes. Therefore, we found that plage regions decrease while facular areas are increasing in SAC 23. However, the decrease in plage regions is seen in small sunspot groups (SGs, contrary to this, these regions in large SGs are comparable to previous SACs or even larger as is also seen in facular areas. Nevertheless, negative correlations between ISSN and SSI data indicate that these variations are in close connection with the classes of sunspots/SGs, faculae and plage regions. Finally, we applied the time series analysis of spectral lines corresponding to the wavelengths 121.5 nm-300.5 nm and made comparisons with the ISSN data. We found an unexpected increase in the 298.5 nm line for the Fe II ion. The variability of Fe II ion 298.5 nm line is in close connection with the facular areas and plage regions, and the sizes of these solar surface indices play an important role for the SSI variability, as well. So, we compared the connection between the sizes of faculae and plage regions, sunspots/SGs, chemical elements and SSI variability. Our future work will be the theoretical study of this connection and developing of a corresponding model.

  17. Recent variability of the solar spectral irradiance and its impact on climate modelling

    Science.gov (United States)

    Ermolli, I.; Matthes, K.; Dudok de Wit, T.; Krivova, N. A.; Tourpali, K.; Weber, M.; Unruh, Y. C.; Gray, L.; Langematz, U.; Pilewskie, P.; Rozanov, E.; Schmutz, W.; Shapiro, A.; Solanki, S. K.; Woods, T. N.

    2013-04-01

    The lack of long and reliable time series of solar spectral irradiance (SSI) measurements makes an accurate quantification of solar contributions to recent climate change difficult. Whereas earlier SSI observations and models provided a qualitatively consistent picture of the SSI variability, recent measurements by the SORCE (SOlar Radiation and Climate Experiment) satellite suggest a significantly stronger variability in the ultraviolet (UV) spectral range and changes in the visible and near-infrared (NIR) bands in anti-phase with the solar cycle. A number of recent chemistry-climate model (CCM) simulations have shown that this might have significant implications on the Earth's atmosphere. Motivated by these results, we summarize here our current knowledge of SSI variability and its impact on Earth's climate. We present a detailed overview of existing SSI measurements and provide thorough comparison of models available to date. SSI changes influence the Earth's atmosphere, both directly, through changes in shortwave (SW) heating and therefore, temperature and ozone distributions in the stratosphere, and indirectly, through dynamical feedbacks. We investigate these direct and indirect effects using several state-of-the art CCM simulations forced with measured and modelled SSI changes. A unique asset of this study is the use of a common comprehensive approach for an issue that is usually addressed separately by different communities. We show that the SORCE measurements are difficult to reconcile with earlier observations and with SSI models. Of the five SSI models discussed here, specifically NRLSSI (Naval Research Laboratory Solar Spectral Irradiance), SATIRE-S (Spectral And Total Irradiance REconstructions for the Satellite era), COSI (COde for Solar Irradiance), SRPM (Solar Radiation Physical Modelling), and OAR (Osservatorio Astronomico di Roma), only one shows a behaviour of the UV and visible irradiance qualitatively resembling that of the recent SORCE

  18. Discussion on the spectral coherence between planetary, solar and climate oscillations: a reply to some critiques

    Science.gov (United States)

    Scafetta, Nicola

    2014-12-01

    During the last few years a number of works have proposed that planetary harmonics regulate solar oscillations. Also the Earth's climate seems to present a signature of multiple astronomical harmonics. Herein I address some critiques claiming that planetary harmonics would not appear in the data. I will show that careful and improved analysis of the available data do support the planetary theory of solar and climate variation also in the critiqued cases. In particular, I show that: (1) high-resolution cosmogenic 10Be and 14C solar activity proxy records both during the Holocene and during the Marine Interglacial Stage 9.3 (MIS 9.3), 325-336 kyear ago, present four common spectral peaks (confidence level ⪆95 %) at about 103, 115, 130 and 150 years (this is the frequency band that generates Maunder and Dalton like grand solar minima) that can be deduced from a simple solar model based on a generic non-linear coupling between planetary and solar harmonics; (2) time-frequency analysis and advanced minimum variance distortion-less response (MVDR) magnitude squared coherence analysis confirm the existence of persistent astronomical harmonics in the climate records at the decadal and multidecadal scales when used with an appropriate window lenght ( L≈110 years) to guarantee a sufficient spectral resolution to solve at least the major astronomical harmonics. The optimum theoretical window length deducible from astronomical considerations alone is, however, L⪆178.4 years because the planetary frequencies are harmonics of such a period. However, this length is larger than the available 164-year temperature signal. Thus, the best coherence test can be currently made only using a single window as long as the temperature instrumental record and comparing directly the temperature and astronomical spectra as done in Scafetta (J. Atmos. Sol. Terr. Phys. 72(13):951-970, 2010) and reconfirmed here. The existence of a spectral coherence between planetary, solar and climatic

  19. Point-focus spectral splitting solar concentrator for multiple cells concentrating photovoltaic system

    International Nuclear Information System (INIS)

    Maragliano, Carlo; Chiesa, Matteo; Stefancich, Marco

    2015-01-01

    In this paper we present and experimentally validate a low-cost design of a spectral splitting concentrator for the efficient conversion of solar energy. The optical device consists of a dispersive prismatic lens made of polycarbonate designed to simultaneously concentrate solar light and split it into its spectral components. With respect to our previous implementation, this device concentrates light along two axes and generates a light pattern compatible with the dimensions of a set of concentrating photovoltaic cells, while providing a higher concentration ratio. The mathematical framework and the constructive approach used for the design are presented and the device performance is simulated using ray-tracing software. We obtain spectral separation in the visible range within a 3 × 1 cm 2 area and a maximum concentration of 210× for a single wavelength. The device is fabricated by injection molding and its performance is experimentally investigated. We measure an optical transmissivity above 90% in the range 400–800 nm and we observe a spectral distribution in good accordance with simulations. Our results demonstrate the feasibility of the device for cost effective high efficiency concentrated photovoltaic systems. (paper)

  20. Making of a solar spectral irradiance dataset I: observations, uncertainties, and methods

    Directory of Open Access Journals (Sweden)

    Schöll Micha

    2016-01-01

    Full Text Available Context. Changes in the spectral solar irradiance (SSI are a key driver of the variability of the Earth’s environment, strongly affecting the upper atmosphere, but also impacting climate. However, its measurements have been sparse and of different quality. The “First European Comprehensive Solar Irradiance Data Exploitation project” (SOLID aims at merging the complete set of European irradiance data, complemented by archive data that include data from non-European missions. Aims. As part of SOLID, we present all available space-based SSI measurements, reference spectra, and relevant proxies in a unified format with regular temporal re-gridding, interpolation, gap-filling as well as associated uncertainty estimations. Methods. We apply a coherent methodology to all available SSI datasets. Our pipeline approach consists of the pre-processing of the data, the interpolation of missing data by utilizing the spectral coherency of SSI, the temporal re-gridding of the data, an instrumental outlier detection routine, and a proxy-based interpolation for missing and flagged values. In particular, to detect instrumental outliers, we combine an autoregressive model with proxy data. We independently estimate the precision and stability of each individual dataset and flag all changes due to processing in an accompanying quality mask. Results. We present a unified database of solar activity records with accompanying meta-data and uncertainties. Conclusions. This dataset can be used for further investigations of the long-term trend of solar activity and the construction of a homogeneous SSI record.

  1. SORCE SOLSTICE FUV Level 3 Solar Spectral Irradiance Daily Means V015 (SOR3SOLFUVD) at GES DISC

    Data.gov (United States)

    National Aeronautics and Space Administration — The SORCE SOLSTICE Far-UV Solar Spectral Irradiance (SSI) data product SOR3SOLFUVD is constructed using measurements from the SOLSTICE FUV instrument, which are...

  2. SORCE SOLSTICE MUV Level 3 Solar Spectral Irradiance Daily Means V015 (SOR3SOLMUVD) at GES DISC

    Data.gov (United States)

    National Aeronautics and Space Administration — The SORCE SOLSTICE Mid-UV Solar Spectral Irradiance (SSI) data product SOR3SOLMUVD is constructed using measurements from the SOLSTICE MUV instrument, which are...

  3. A Compact Solar Spectral Irradiance Monitor for Future Small Satellite and CubeSat Science Opportunities

    Science.gov (United States)

    Richard, E. C.; Harber, D.; Snow, M. A.; Harder, J. W.

    2013-12-01

    Accurate and continuous measurements of solar spectral irradiance (SSI) is recognized as being increasingly important to advancing our understanding of the solar influence on Earth's climate. For example, the magnitude of SSI UV variability has significant implications, both directly and indirectly, for the response of the stratosphere and mesosphere, whereas the visible and near infrared SSI variability influences the radiative balance, thermal structure, and dynamics of the lower atmosphere and ocean layers. Recent SSI measurements are providing critical inputs in evaluating and improving present climate models, however they are not yet of sufficient accuracy to stand alone without overlapping records - gaps in the observational record, caused by future mission delays or early failures of existing missions, effectively destroy our ability to link records from different instruments into a continuous, long-term climate quality record. Recent advancements in calibration facilities and techniques make it now possible to improve significantly the accuracy and traceability of future SSI observations and assure quantification of uncertainty as input to increasingly more sophisticated climate models. The goal of the proposed compact SSI monitor is to cover 200-2400 nm with the required SI-traceable accuracy and on-orbit stability to meet the solar input measurement requirements defined in the Earth Science Decadal Survey for establishing benchmark climate records. Building upon our experiences and resources from the Total and Spectral Solar Irradiance Sensor (TSIS) program, the instrument will reduce the cost, size, and characterization and calibration schedule of a solar spectral irradiance monitor with SI-traceable absolute calibration at the 0.2% uncertainty level (k=1) while maintaining 100 ppm relative stability. System level performance characterizations and final end-to-end absolute irradiance calibration will be accomplished with the LASP Spectral Radiometer

  4. Solution-processed, nanostructured hybrid solar cells with broad spectral sensitivity and stability.

    Science.gov (United States)

    Zhou, Renjia; Zheng, Ying; Qian, Lei; Yang, Yixing; Holloway, Paul H; Xue, Jiangeng

    2012-06-07

    Hybrid organic-inorganic solar cells, as an alternative to all-organic solar cells, have received significant attention for their potential advantages in combining the solution-processability and versatility of organic materials with high charge mobility and environmental stability of inorganic semiconductors. Here we report efficient and air-stable hybrid organic-inorganic solar cells with broad spectral sensitivity based on a low-gap polymer poly[2,6-(4,4-bis-(2-ethylhexyl)-4H-cyclopenta[2,1-b;3,4-b']-dithiophene)-alt-4,7-(2,1,3-benzothiadiazole)] (PCPDTBT) and spherical CdSe nanoparticles. The solvents used for depositing the hybrid PCPDTBT:CdSe active layer were shown to strongly influence the film morphology, and subsequently the photovoltaic performance of the resulted solar cells. Appropriate post-deposition annealing of the hybrid film was also shown to improve the solar cell efficiency. The inclusion of a thin ZnO nanoparticle layer between the active layer and the metal cathode leads to a significant increase in device efficiency especially at long wavelengths, due to a combination of optical and electronic effects including more optimal light absorption in the active layer and elimination of unwanted hole leakage into the cathode. Overall, maximum power conversion efficiencies up to 3.7 ± 0.2% and spectral sensitivity extending above 800 nm were achieved in such PCPDTBT:CdSe nanosphere hybrid solar cells. Furthermore, the devices with a ZnO nanoparticle layer retained ∼70% of the original efficiency after storage under ambient laboratory conditions for over 60 days without any encapsulation.

  5. Spectrally-resolved Soft X-ray Observations and the Temperature Structure of the Solar Corona

    Science.gov (United States)

    Caspi, Amir; Warren, Harry; McTiernan, James; Woods, Thomas N.

    2015-04-01

    Solar X-ray observations provide important diagnostics of plasma heating and particle acceleration, during solar flares and quiescent periods. How the corona is heated to its ~1-3 MK nominal temperature remains one of the fundamental unanswered questions of solar physics; heating of plasma to tens of MK during solar flares -- particularly to the hottest observed temperatures of up to ~50 MK -- is also still poorly understood. Soft X-ray emission (~0.1-10 keV; or ~0.1-10 nm) is particularly sensitive to hot coronal plasma and serves as a probe of the thermal processes driving coronal plasma heating. Spectrally- and temporally-resolved measurements are crucial for understanding these energetic processes, but there have historically been very few such observations. We present new solar soft X-ray spectra from the Amptek X123-SDD, measuring quiescent solar X-ray emission from ~0.5 to ~30 keV with ~0.15 keV FWHM resolution from two SDO/EVE calibration sounding rocket underflights in 2012 and 2013. Combined with observations from RHESSI, GOES/XRS, SDO/EVE, and SDO/AIA, the temperature distribution derived from these data suggest significant hot (5-10 MK) emission from active regions, and the 2013 spectra suggest a low-FIP enhancement of only ~1.6 relative to the photosphere, 40% of the usually-observed value from quiescent coronal plasma. We explore the implications of these findings on coronal heating. We discuss future missions for spectrally-resolved soft X-ray observations using the X123-SDD, including the upcoming MinXSS 3U CubeSat using the X123-SDD and scheduled for deployment in mid-2015, and the CubIXSS 6U CubeSat mission concept.

  6. Estimating solar ultraviolet irradiance (290-385 nm by means of the spectral parametric models: SPCTRAL2 and SMARTS2

    Directory of Open Access Journals (Sweden)

    I. Foyo-Moreno

    2000-11-01

    Full Text Available Since the discovery of the ozone depletion in Antarctic and the globally declining trend of stratospheric ozone concentration, public and scientific concern has been raised in the last decades. A very important consequence of this fact is the increased broadband and spectral UV radiation in the environment and the biological effects and heath risks that may take place in the near future. The absence of widespread measurements of this radiometric flux has lead to the development and use of alternative estimation procedures such as the parametric approaches. Parametric models compute the radiant energy using available atmospheric parameters. Some parametric models compute the global solar irradiance at surface level by addition of its direct beam and diffuse components. In the present work, we have developed a comparison between two cloudless sky parametrization schemes. Both methods provide an estimation of the solar spectral irradiance that can be integrated spectrally within the limits of interest. For this test we have used data recorded in a radiometric station located at Granada (37.180°N, 3.580°W, 660 m a.m.s.l., an inland location. The database includes hourly values of the relevant variables covering the years 1994-95. The performance of the models has been tested in relation to their predictive capability of global solar irradiance in the UV range (290–385 nm. After our study, it appears that information concerning the aerosol radiative effects is fundamental in order to obtain a good estimation. The original version of SPCTRAL2 provides estimates of the experimental values with negligible mean bias deviation. This suggests not only the appropriateness of the model but also the convenience of the aerosol features fixed in it to Granada conditions. SMARTS2 model offers increased flexibility concerning the selection of different aerosol models included in the code and provides the best results when the selected models are those

  7. Selection/extraction of spectral regions for autofluorescence spectra measured in the oral cavity

    NARCIS (Netherlands)

    Skurichina, M; Paclik, P; Duin, RPW; de Veld, D; Sterenborg, HJCM; Witjes, MJH; Roodenburg, JLN; Fred, A; Caelli, T; Duin, RPW; Campilho, A; DeRidder, D

    2004-01-01

    Recently a number of successful algorithms to select/extract discriminative spectral regions was introduced. These methods may be more beneficial than the standard feature selection/extraction methods for spectral classification. In this paper, on the example of autofluorescence spectra measured in

  8. New Solar Soft X-Ray (SXR) Spectral Irradiance Measurements Bridge the SDO and RHESSI Spectral Gap to Study Flare Energetics

    Science.gov (United States)

    Woods, T. N.; Jones, A.; Mason, J.; Moore, C.; Eparvier, F.; Caspi, A.; Chamberlin, P.

    2016-10-01

    The extreme ultraviolet (EUV) spectrum is rich in many different emission lines that reveal plasma characteristics concerning active region evolution and explosive energy release during coronal eruptions. Solar EUV imagers, such as SDO AIA, provide insight into the location, thermal structure, and dynamics of the coronal eruptions and associated flares. In addition, the solar EUV spectral irradiance from SDO EVE, with its higher spectral resolution, provides more detailed thermal evolution of the eruption and has better characterized some aspects of the eruptions such as relationship of coronal dimming and mass loss and post-eruption coronal loop cooling. Complementary to SDO are hard x-ray (HXR) measurements by RHESSI that have clarified the initiation of energy release from magnetic reconnection in the corona. New solar soft x-ray (SXR) spectral irradiance from the Miniature X-ray Solar Spectrometer (MinXSS) CubeSat is now bridging this spectral gap between SDO EUV and RHESSI HXR observations. MinXSS-1 was deployed from the ISS in May 2016 for a 1-year mission, and MinXSS-2 is being launched in October 2016 for a 5-year mission. The energy release during solar flares is expected to peak in the SXR and thus the SXR has been monitored with GOES broadband photometers for decades, but there has been very limited SXR spectral measurements. With the new and unique MinXSS measurements of the SXR spectral variability during flares, coupled with solar SXR images from Hinode, EUV data from SDO, and HXR data from RHESSI, the processes for releasing energy during an eruption and affecting post-eruption thermal evolution can be explored in more detail. Furthermore, the new SXR spectral irradiance measurements can help improve the accuracy of broad band SXR measurements by GOES XRS, SDO EVE ESP, and XPS aboard TIMED and SORCE. Such improvements can lead to better understanding the solar impacts in Earth's ionosphere and thermosphere and how they might affect some of our space

  9. Development of Surfaces Optically Suitable for Flat Solar Panels. [using a reflectometer which separately evaluates spectral and diffuse reflectivities of surfaces

    Science.gov (United States)

    1979-01-01

    A reflectometer which can separately evaluate the spectral and diffuse reflectivities of surfaces is described. A phase locked detection system for the reflectometer is also described. A selective coating on aluminum potentially useful for flat plate solar collector applications is presented. The coating is composed of strongly bound copper oxide (divalent) and is formed by an etching process performed on an aluminum alloy with high copper content. Fabrication costs are expected to be small due to the one stop fabrication process. A number of conclusions gathered from the literature as to the required optical properties of flat plate solar collectors are discussed.

  10. Fabrication of high efficacy selective solar absorbers

    CSIR Research Space (South Africa)

    Tile, N

    2012-03-01

    Full Text Available Peer-Reviewed Journal Papers: K.T. Roro, N. Tile, B.W. Mwakikunga, B. Yalisi, A. Forbes (2012). Solar absorption and thermal emission properties of Multiwall carbonnanotube/nickel oxide nanocomposite thin films synthesized by sol-gel process..., Materials Science and Engineering B 177,581? 587. K.T. Roro, N. Tile, A. Forbes (2012), Preparation and characterization of carbon/nickel oxide nanocomposite coatings for solar absorber applications, Applied Surface Science 258, 7174? 7180. K.T. Roro...

  11. Magnetic Reconnection May Control the Ion-scale Spectral Break of Solar Wind Turbulence

    Science.gov (United States)

    Vech, Daniel; Mallet, Alfred; Klein, Kristopher G.; Kasper, Justin C.

    2018-03-01

    The power spectral density of magnetic fluctuations in the solar wind exhibits several power-law-like frequency ranges with a well-defined break between approximately 0.1 and 1 Hz in the spacecraft frame. The exact dependence of this break scale on solar wind parameters has been extensively studied but is not yet fully understood. Recent studies have suggested that reconnection may induce a break in the spectrum at a “disruption scale” {λ }{{D}}, which may be larger than the fundamental ion kinetic scales, producing an unusually steep spectrum just below the break. We present a statistical investigation of the dependence of the break scale on the proton gyroradius ρ i , ion inertial length d i , ion sound radius ρ s , proton–cyclotron resonance scale ρ c , and disruption scale {λ }{{D}} as a function of {β }\\perp i. We find that the steepest spectral indices of the dissipation range occur when β e is in the range of 0.1–1 and the break scale is only slightly larger than the ion sound scale (a situation occurring 41% of the time at 1 au), in qualitative agreement with the reconnection model. In this range, the break scale shows a remarkably good correlation with {λ }{{D}}. Our findings suggest that, at least at low β e , reconnection may play an important role in the development of the dissipation range turbulent cascade and cause unusually steep (steeper than ‑3) spectral indices.

  12. Spectral solar irradiance and some optical properties for various polluted atmospheres

    International Nuclear Information System (INIS)

    Jacovides, Constantinos P.; Asimakopoulos, Demosthenis N.; Steven, Michael D.

    2000-01-01

    Using ground-based spectroradiometric measurements taken over the Athens atmosphere during May 1995, the influence of gaseous pollutants and aerosol on the spectral radiant energy distribution was investigated. It was found that spectral measurements exhibited variations based on various polluted urban atmospheric conditions as determined via gaseous pollutants record analysis. The relative attenuations cause by gaseous pollutants and aerosol can exceed 27%, 17% and 16% in the global ultraviolet, visible and near-infrared portions of the solar spectrum respectively, as compared to 'background' values. In contrast, an enhancement of the near-infrared diffuse component by 66%, was observed, while in visible and ultraviolet bands the relative increases reached 54% and 21% respectively. Experimental total Rayleigh-corrected and spectral aerosol optical depths were retrieved, representing differences in polluted air over the Athens atmosphere. The diffuse component accounts for more than 80% of the total radiation field under high polluted atmosphere. The observed differences of solar radiation between the Athens center and at a nearby suburban site are a manifestation of contrasting air properties provided mainly by automotive traffic. (Author)

  13. Prototype of Cryogenic Solar Absolute Radiometer and Transfer Radiometer for On-Board Calibration of Spectral Earth Imager

    Science.gov (United States)

    Zajiczek, L.; Winkler, R.; Hobson, T.; Green, P.; Fox, N.

    2018-02-01

    We describe a prototype calibration system for the Traceable Radiometry Underpinning Terrestrial- and Helio-Studies (TRUTHS) satellite mission. We outline the design and testing of key system components, including the Cryogenic Solar Absolute Radiometer (CSAR). CSAR is designed to make Total Solar Irradiance (TSI) measurements with a standard uncertainty of < 0.01 % and provide SI-traceable calibration of a hyperspectral Earth imager (EI) over the wavelength range 320 nm – 2450 nm. The EI is designed to make Solar Spectral Irradiance (SSI) and spectral radiance measurements with a standard uncertainty of < 0.3 %.

  14. From UV Protection to Protection in the Whole Spectral Range of the Solar Radiation: New Aspects of Sunscreen Development.

    Science.gov (United States)

    Zastrow, Leonhard; Meinke, Martina C; Albrecht, Stephanie; Patzelt, Alexa; Lademann, Juergen

    2017-01-01

    Sunscreens have been constantly improving in the past few years. Today, they provide an efficient protection not only in the UVB but also in the UVA spectral region of the solar radiation. Recently it could be demonstrated that 50% of all free radicals induced in the skin due to solar radiation are formed in the visible and infrared spectral region. The good protective efficacy of sunscreens in the UV region prompts people to stay much longer in the sun than if they had left their skin unprotected. However, as no protection in the visible and infrared spectral region is provided, high amounts of free radicals are induced here that could easily exceed the critical radical concentration. This chapter describes how the effect of sunscreens can be extended to cover also the visible and infrared spectral region of the solar radiation by adding pigments and antioxidants with high radical protection factors to the sunscreen formulations.

  15. Hyper-spectral frequency selection for the classification of vegetation diseases

    OpenAIRE

    Dijkstra, Klaas; van de Loosdrecht, Jaap; Schomaker, Lambert; Wiering, Marco

    2017-01-01

    Reducing the use of pesticides by early visual detection of diseases in precision agriculture is important. Because of the color similarity between potato-plant diseases, narrow band hyper-spectral imaging is required. Payload constraints on unmanned aerial vehicles require reduc- tion of spectral bands. Therefore, we present a methodology for per-patch classification combined with hyper-spectral band selection. In controlled experiments performed on a set of individual leaves, we measure the...

  16. Low Cost High Performance Nanostructured Spectrally Selective Coating

    Energy Technology Data Exchange (ETDEWEB)

    Jin, Sungho [Univ. of California, San Diego, CA (United States)

    2017-04-05

    Sunlight absorbing coating is a key enabling technology to achieve high-temperature high-efficiency concentrating solar power operation. A high-performance solar absorbing material must simultaneously meet all the following three stringent requirements: high thermal efficiency (usually measured by figure of merit), high-temperature durability, and oxidation resistance. The objective of this research is to employ a highly scalable process to fabricate and coat black oxide nanoparticles onto solar absorber surface to achieve ultra-high thermal efficiency. Black oxide nanoparticles have been synthesized using a facile process and coated onto absorber metal surface. The material composition, size distribution and morphology of the nanoparticle are guided by numeric modeling. Optical and thermal properties have been both modeled and measured. High temperature durability has been achieved by using nanocomposites and high temperature annealing. Mechanical durability on thermal cycling have also been investigated and optimized. This technology is promising for commercial applications in next-generation high-temperature concentration solar power (CSP) plants.

  17. Spectral and Concentration Sensitivity of Multijunction Solar Cells at High Temperature: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Friedman, Daniel J.; Steiner, Myles A.; Perl, Emmett E.; Simon, John

    2017-06-14

    We model the performance of two-junction solar cells at very high temperatures of ~400 degrees C and beyond for applications such as hybrid PV/solar-thermal power production, and identify areas in which the design and performance characteristics behave significantly differently than at more conventional near-room-temperature operating conditions. We show that high-temperature operation reduces the sensitivity of the cell efficiency to spectral content, but increases the sensitivity to concentration, both of which have implications for energy yield in terrestrial PV applications. For other high-temperature applications such as near-sun space missions, our findings indicate that concentration may be a useful tool to enhance cell efficiency.

  18. TESIS experiment on study of solar corona in EUV spectral range (CORONAS-PHOTON project)

    International Nuclear Information System (INIS)

    Kuzin, S.V.; Zhitnik, I.A.; Ignat'ev, A.P.; Mitrofanov, A.V.; Pertsov, A.A.; Bugaenko, O.I.

    2005-01-01

    A new orbital station, namely: the CORONAS-PHOTON one (to be launched in 2006) equipped with systems to explore Sun at the intensification period of the solar activity 24-th cycle and at its peak is being designed within the framework of the CORONAS National Sun Space Exploration Program. The station equipment consists of systems to observe Sun within the spectral soft X-ray and vacuum ultraviolet bands. Paper lists and describes the TESIS experiment tools designed for the CORONAS-PHOTON Project to ensure the Sun atmospheric research within short-wave band [ru

  19. Ion-Scale Spectral Break in the Normal Plasma Beta Range in the Solar Wind Turbulence

    Science.gov (United States)

    Wang, X.; Tu, C.-Y.; He, J.-S.; Wang, L.-H.

    2018-01-01

    The spectral break (fb) of magnetic fluctuations at the ion scale in the solar wind is considered to give important clue on the turbulence dissipation mechanism. Among several possible mechanisms, the most notable two are related respectively to proton thermal gyroradius ρi and proton inertial length di. The corresponding frequencies of them are fρi=VSW/(2πρi) and fdi=VSW/(2πdi), respectively, where VSW is the solar wind speed. However, no definite conclusion has been given for which one is more reasonable because the two parameters have similar value when plasma beta β ˜ 1. Here we do a statistical study to see if the two ratios fb/fρi and fb/fdi have different dependence on β in the solar wind turbulence with 0.1 fdi is statistically not dependent on β, and the average value of it is 0.48 ± 0.06. However, fb/fρi increases with increasing β clearly and is significantly smaller than fb/fdi when β fdi, and the influence of β could be negligible in the studied β range. It indicates a preference of the dissipation mechanism associated with di in the solar wind with 0.1 < β < 0.8. Further theoretical studies are needed to give detailed explanation.

  20. Selective blacks for enhanced photothermal solar energy conversion

    Science.gov (United States)

    Agarwal, R. C.; Pillai, P. K. C.

    The optical and physical requirements of selective surfaces for maximum absorption of solar thermal energy are reviewed, along with processes to fabricate the selective coatings. Noting that the solar energy which reaches the ground is usually in wavelengths of 0.3-2 microns, the desired qualities of coatings are listed as stability of performance, good adherence to the substructure, ease of application, low emissivity above two microns, and economical fabrication. Selective surfaces comprise absorber-reflector tandems, which allow or reflect IR passage, multilayer interference stacks, which involve successive deposition of metallic coatings, and controlled surface morphology, which entails either geometric irregularities, Mie scattering films, corrugated surfaces, or wire mesh surfaces. Preparation can be by electrodeposition, chemical conversion, spray pyrolysis, paint coatings, vacuum deposition, and chemical vapor deposition (CVD), which is stressed as offering the most attractive option for economical large scale coating of solar selective surfaces.

  1. Spectral region identification versus individual channel selection in supervised dimensionality reduction of hyperspectral image data

    Science.gov (United States)

    Aria, S. Enayat Hosseini; Menenti, Massimo; Gorte, Ben G. H.

    2017-10-01

    Hyperspectral images may be applied to classify objects in a scene. The redundancy in hyperspectral data implies that fewer spectral features might be sufficient for discriminating the objects captured in a scene. The availability of labeled classes of several areas in a scene paves the way for a supervised dimensionality reduction, i.e., using a discrimination measure between the classes in a scene to select spectral features. We show that averaging adjacent spectral channels and using wider spectral regions yield a better class separability than the selection of individual channels from the original hyperspectral dataset. We used a method named spectral region splitting (SRS), which creates a new feature space by averaging neighboring channels. In addition to the common benefits of channel selection methods, the algorithm constructs wider spectral regions when it is useful. Using different class separability measures over various datasets resulted in a better discrimination between the classes than the best-selected channels using the same measure. The reason is that the wider spectral regions led to a reduction in intraclass distances and an improvement in class discrimination. The overall classification accuracy of two hyperspectral scenes gave an increase of about two-percent when using the spectral regions determined by applying SRS.

  2. Cost reductions in photovoltaics - Solar selection

    International Nuclear Information System (INIS)

    Rentzing, S.

    2009-01-01

    This article discusses the effect of the economic recession on the solar industry. Whilst certain companies fight to survive, margins are sinking and badly-positioned companies and expensive technologies are being pushed out of the market. The author goes on to take a look at business figures and the throttling back of production, even in China. Sinking module prices and sufficient supplies of silicon are commented on. Top companies that provide good value for money are noted and markets such as that in the USA will, according to the author, develop further, thanks to government funding

  3. Development of Solar Drying Model for Selected Cambodian Fish Species

    Directory of Open Access Journals (Sweden)

    Anna Hubackova

    2014-01-01

    Full Text Available A solar drying was investigated as one of perspective techniques for fish processing in Cambodia. The solar drying was compared to conventional drying in electric oven. Five typical Cambodian fish species were selected for this study. Mean solar drying temperature and drying air relative humidity were 55.6°C and 19.9%, respectively. The overall solar dryer efficiency was 12.37%, which is typical for natural convection solar dryers. An average evaporative capacity of solar dryer was 0.049 kg·h−1. Based on coefficient of determination (R2, chi-square (χ2 test, and root-mean-square error (RMSE, the most suitable models describing natural convection solar drying kinetics were Logarithmic model, Diffusion approximate model, and Two-term model for climbing perch and Nile tilapia, swamp eel and walking catfish and Channa fish, respectively. In case of electric oven drying, the Modified Page 1 model shows the best results for all investigated fish species except Channa fish where the two-term model is the best one. Sensory evaluation shows that most preferable fish is climbing perch, followed by Nile tilapia and walking catfish. This study brings new knowledge about drying kinetics of fresh water fish species in Cambodia and confirms the solar drying as acceptable technology for fish processing.

  4. Spectral analysis to detection of short circuit fault of solar photovoltaic modules in strings

    International Nuclear Information System (INIS)

    Sevilla-Camacho, P.Y.; Robles-Ocampo, J.B.; Zuñiga-Reyes, Marco A.

    2017-01-01

    This research work presents a method to detect the number of short circuit faulted solar photovoltaic modules in strings of a photovoltaic system by taking into account speed, safety, and non-use of sensors and specialized and expensive equipment. The method consists on apply the spectral analysis and statistical techniques to the alternating current output voltage of a string and detect the number of failed modules through the changes in the amplitude of the component frequency of 12 kHz. For that, the analyzed string is disconnected of the array; and a small pulsed voltage signal of frequency of 12 kHz introduces him under dark condition and controlled temperature. Previous to the analysis, the signal is analogic filtered in order to reduce the direct current signal component. The spectral analysis technique used is the Fast Fourier Transform. The obtained experimental results were validated through simulation of the alternating current equivalent circuit of a solar cell. In all experimental and simulated test, the method allowed to identify correctly the number of photovoltaic modules with short circuit in the analyzed string. (author)

  5. A large-area, LED-based spectral response measurement system for solar PV device characterization

    Science.gov (United States)

    Hamadani, Behrang; Roller, John; Yoon, Howard; Dougherty, Brian

    2012-02-01

    Accurate and reliable measurement of the spectral responsivity (SR) of a solar cell is an important step in evaluating the electrical performance of competing photovoltaic (PV) technologies. We have investigated ways to measure the spectral responsivity, and hence the external quantum efficiency, of solar cells using measurement techniques that employ light emitting diodes (LEDs). Our setup includes one or more plates of compactly-installed, high-powered LEDs each containing up to 32 different LEDs that span the wavelength range of 375 nm to 1200 nm. Each LED plate is placed at the entrance of a tapered, highly reflective light guide for light mixing and large-area projection. Two unique measurement techniques have been investigated at NIST. The first technique consists of an LED sweep algorithm where a pulsed signal is applied to a given LED and the photogenerated current from the device under test is recorded using a lock-in technique. In the second SR technique, 32 variable-frequency, pulsed signals are applied to all LEDs at the same time, while recording the photogenerated current by a spectrum analyzer in the frequency domain. We will describe the uniqueness and advantages offered by each technique in detail and compare the accuracy of the two methods. A scheme for providing light bias and its impact on the SR measurements will be reported.

  6. Imaging Grating Spectrometer (I-GRASP) for Solar Soft X-Ray Spectral Measurements in Critically Under-Observed 0.5 - 7 nm Spectral Range

    Science.gov (United States)

    Didkovsky, L. V.; Wieman, S. R.; Chao, W.; Woods, T. N.; Jones, A. R.; Thiemann, E.; Mason, J. P.

    2016-12-01

    We discuss science and technology advantages of the Imaging Grating Spectrometer (I-GRASP) based on a novel transmission diffracting grating (TDG) made possible by technology for fabricating Fresnel zone plates (ZPs) developed at the Lawrence Berkeley National Laboratory (LBNL). Older version TDGs with 200 nm period available in the 1990s became a proven technology for providing 21 years of regular measurements of solar EUV irradiance. I-GRASP incorporates an advanced TDG with a grating period of 50 nm providing four times better diffraction dispersion than the 200 nm period gratings used in the SOHO/CELIAS/SEM, the SDO/EVE/ESP flight spectrophotometers, and the EVE/SAM sounding rocket channel. Such new technology for the TDG combined with a back-illuminated 2000 x 1504 CMOS image sensor with 7 micron pixels, will provide spatially-and-spectrally resolved images and spectra from individual Active Regions (ARs) and solar flares with high (0.15 nm) spectral resolution. Such measurements are not available in the spectral band from about 2 to 6 nm from existing or planned spectrographs and will be significantly important to study ARs and solar flare temperatures and dynamics, to improve existing spectral models, e.g. CHIANTI, and to better understand processes in the Earth's atmosphere processes. To test this novel technology, we have proposed to the NASA LCAS program an I-GRASP version for a sounding rocket flight to increase the TDG TRL to a level appropriate for future CubeSat projects.

  7. COHERENT EVENTS AND SPECTRAL SHAPE AT ION KINETIC SCALES IN THE FAST SOLAR WIND TURBULENCE

    International Nuclear Information System (INIS)

    Lion, Sonny; Alexandrova, Olga; Zaslavsky, Arnaud

    2016-01-01

    In this paper we investigate spectral and phase coherence properties of magnetic fluctuations in the vicinity of the spectral transition from large, magnetohydrodynamic to sub-ion scales using in situ measurements of the Wind spacecraft in a fast stream. For the time interval investigated by Leamon et al. (1998) the phase coherence analysis shows the presence of sporadic quasi-parallel Alfvén ion cyclotron (AIC) waves as well as coherent structures in the form of large-amplitude, quasi-perpendicular Alfvén vortex-like structures and current sheets. These waves and structures importantly contribute to the observed power spectrum of magnetic fluctuations around ion scales; AIC waves contribute to the spectrum in a narrow frequency range whereas the coherent structures contribute to the spectrum over a wide frequency band from the inertial range to the sub-ion frequency range. We conclude that a particular combination of waves and coherent structures determines the spectral shape of the magnetic field spectrum around ion scales. This phenomenon provides a possible explanation for a high variability of the magnetic power spectra around ion scales observed in the solar wind.

  8. Fresnel lens solar concentrator design and spectral distribution on focus surface

    Science.gov (United States)

    Shen, Zuo Chun; Lu, Yu; Lu, Jian Ye

    2011-09-01

    It is necessary to analysize the spectral distribution of sun light on focal spot as well as its condenser ratio, both in the study of the different quantum efficiency of photoelectric materials and the different spectral absorption coefficient for the laser medium. Based on the absorption spectrum of Cr/Nd:YAG ceramic, this paper addresses itself to the study of convex Fresnel lens focus solar light and choose spectrum. Set Parameters which are used for the design of Fresnel lens such as the ring width, height the focal length as well as the design of spectrum can be changed and the spectral ditribution on focal plane can be controlled. By way of simulation, a method through which is the best optical design for matching Cr/Nd:YAG ceramic absorption spectrum can be found. The maximum absorb power density in six optimum design is 288.5 W/cm2, which is 3.2-18.5% higher than absorb power density in six initial design based on purpose of obtaining the maximum power density.

  9. The Herschel/HIFI unbiased spectral survey of the solar-mass protostar IRAS16293

    Science.gov (United States)

    Bottinelli, S.; Caux, E.; Cecarelli, C.; Kahane, C.

    2012-03-01

    Unbiased spectral surveys are powerful tools to study the chemistry and the physics of star forming regions, because they can provide a complete census of the molecular content and the observed lines probe the physical structure of the source. While unbiased surveys at the millimeter and sub-millimeter wavelengths observable from ground-based telescopes have previously been performed towards several high-mass protostars, very little data exist on low-mass protostars, with only one such ground-based survey carried out towards this kind of object. However, since low-mass protostars are believed to resemble our own Sun's progenitor, the information provided by spectral surveys is crucial in order to uncover the birth mechanisms of low-mass stars and hence of our Sun. To help fill up this gap in our understanding, we carried out an almost complete spectral survey towards the solar-type protostar IRAS16293-2422 with the HIFI instrument onboard Herschel. The observations covered a range of about 700 GHz, in which a few hundreds lines were detected with more than 3σ confidence interval certainty and identified. All the detected lines which were free from obvious blending effects were fitted with Gaussians to estimate their basic kinematic properties. Contrarily to what is observed in the millimeter range, no lines from complex organic molecules have been observed. In this work, we characterize the different components of IRAS16293-2422 (a known binary at least) by analyzing the numerous emission and absorption lines identified.

  10. Silicon spectral response extension through single wall carbon nanotubes in hybrid solar cells

    KAUST Repository

    Del Gobbo, Silvano

    2013-01-01

    Photovoltaic devices based on single wall carbon nanotubes (SWCNTs) and n-silicon multiple heterojunctions have been fabricated by a SWCNT film transferring process. We report on the ability of the carbon nanotubes to extend the Si spectral range towards the near ultraviolet (UV) and the near infrared regions. Semiconducting and about metallic SWCNT networks have been studied as a function of the film sheet resistance, Rsh. Optical absorbance and Raman spectroscopy have been used to assign nanotube chirality and electronic character. This gave us hints of evidence of the participation of the metal nanotubes in the photocurrent generation. Moreover, we provide evidence that the external quantum efficiency spectral range can be modulated as a function of the SWCNT network sheet resistance in a hybrid SWCNT/Si solar cell. This result will be very useful to further design/optimize devices with improved performance in spectral regions generally not covered by conventional Si p-n devices. © 2013 The Royal Society of Chemistry.

  11. Climate responses to SATIRE and SIM-based spectral solar forcing in a 3D atmosphere-ocean coupled GCM

    Science.gov (United States)

    Wen, Guoyong; Cahalan, Robert F.; Rind, David; Jonas, Jeffrey; Pilewskie, Peter; Wu, Dong L.; Krivova, Natalie A.

    2017-03-01

    We apply two reconstructed spectral solar forcing scenarios, one SIM (Spectral Irradiance Monitor) based, the other the SATIRE (Spectral And Total Irradiance REconstruction) modeled, as inputs to the GISS (Goddard Institute for Space Studies) GCMAM (Global Climate Middle Atmosphere Model) to examine climate responses on decadal to centennial time scales, focusing on quantifying the difference of climate response between the two solar forcing scenarios. We run the GCMAM for about 400 years with present day trace gas and aerosol for the two solar forcing inputs. We find that the SIM-based solar forcing induces much larger long-term response and 11-year variation in global averaged stratospheric temperature and column ozone. We find significant decreasing trends of planetary albedo for both forcing scenarios in the 400-year model runs. However the mechanisms for the decrease are very different. For SATIRE solar forcing, the decreasing trend of planetary albedo is associated with changes in cloud cover. For SIM-based solar forcing, without significant change in cloud cover on centennial and longer time scales, the apparent decreasing trend of planetary albedo is mainly due to out-of-phase variation in shortwave radiative forcing proxy (downwelling flux for wavelength >330 nm) and total solar irradiance (TSI). From the Maunder Minimum to present, global averaged annual mean surface air temperature has a response of 0.1 °C to SATIRE solar forcing compared to 0.04 °C to SIM-based solar forcing. For 11-year solar cycle, the global surface air temperature response has 3-year lagged response to either forcing scenario. The global surface air 11-year temperature response to SATIRE forcing is about 0.12 °C, similar to recent multi-model estimates, and comparable to the observational-based evidence. However, the global surface air temperature response to 11-year SIM-based solar forcing is insignificant and inconsistent with observation-based evidence.

  12. Spectral splitting photovoltaics using perovskite and wideband dye-sensitized solar cells.

    Science.gov (United States)

    Kinoshita, Takumi; Nonomura, Kazuteru; Jeon, Nam Joong; Giordano, Fabrizio; Abate, Antonio; Uchida, Satoshi; Kubo, Takaya; Seok, Sang Il; Nazeeruddin, Mohammad Khaja; Hagfeldt, Anders; Grätzel, Michael; Segawa, Hiroshi

    2015-11-05

    The extension of the light absorption of photovoltaics into the near-infrared region is important to increase the energy conversion efficiency. Although the progress of the lead halide perovskite solar cells is remarkable, and high conversion efficiency of >20% has been reached, their absorption limit on the long-wavelength side is ∼800 nm. To further enhance the conversion efficiency of perovskite-based photovoltaics, a hybridized system with near-infrared photovoltaics is a useful approach. Here we report a panchromatic sensitizer, coded DX3, that exhibits a broad response into the near-infrared, up to ∼1100 nm, and a photocurrent density exceeding 30 mA cm(-2) in simulated air mass 1.5 standard solar radiation. Using the DX3-based dye-sensitized solar cell in conjunction with a perovskite cell that harvests visible light, the hybridized mesoscopic photovoltaics achieved a conversion efficiency of 21.5% using a system of spectral splitting.

  13. SPECTRAL PROPERTIES OF LARGE GRADUAL SOLAR ENERGETIC PARTICLE EVENTS. I. FE, O, AND SEED MATERIAL

    Energy Technology Data Exchange (ETDEWEB)

    Desai, M. I.; Dayeh, M. A.; Ebert, R. W.; Mccomas, D. J.; Schwadron, N. A. [Southwest Research Institute, 6220 Culebra Road, San Antonio, TX 78238 (United States); Mason, G. M. [Johns Hopkins University/Applied Physics Laboratory, Laurel, MD 20723 (United States); Li, G. [CSPAR, University of Alabama in Huntsville, Huntsville, AL 35756 (United States); Cohen, C. M. S.; Mewaldt, R. A. [California Institute of Technology, Pasadena, CA 91125 (United States); Smith, C. W., E-mail: mdesai@swri.edu [Department of Physics and Space Science Center, University of New Hampshire, Durham, NH 03824 (United States)

    2016-01-10

    We have surveyed ∼0.1–100 MeV nucleon{sup −1} O and Fe fluence spectra during 46 isolated, large gradual SEP events observed at ACE during solar cycles 23 and 24. Most SEP spectra are well represented by the four-parameter Band function with a normalization constant, low-energy spectral slope, high-energy spectral slope, and break energy. The O and Fe spectral slopes are similar and most spectra steepen above the break energy, probably due to common acceleration and transport processes affecting different ion species. SEP spectra above the break energies depend on the origin of the seed population; larger contributions of suprathermal flare material result in higher Fe/O ratios and flatter spectra at higher energies. SEP events with steeper O spectra at low energies and higher break energies are associated with slower coronal mass ejections (CMEs), while those associated with fast (>2000 km s{sup −1}) CMEs and ground level enhancements have harder or flatter spectra at low and high energies, and O break energies between ∼1 and 10 MeV nucleon{sup −1}. The latter events are enriched in {sup 3}He and higher-energy Fe, and have Fe spectra that rollover at significantly lower energies compared with O, probably because Fe ions with smaller Q/M ratios can escape from the distant shock more easily than O ions with larger Q/M ratios. We conclude that SEP spectral properties result from many complex and competing effects, namely Q/M-dependent scattering, shock properties, and the origin of the seed populations, all of which must be taken into account to develop a comprehensive picture of CME-driven shock acceleration of large gradual SEP events.

  14. SPECTRAL PROPERTIES OF LARGE GRADUAL SOLAR ENERGETIC PARTICLE EVENTS. II. SYSTEMATIC Q/M DEPENDENCE OF HEAVY ION SPECTRAL BREAKS

    Energy Technology Data Exchange (ETDEWEB)

    Desai, M. I.; Dayeh, M. A.; Ebert, R. W.; Schwadron, N. A. [Southwest Research Institute, 6220 Culebra Road, San Antonio, TX 78238 (United States); Mason, G. M. [Johns Hopkins University/Applied Physics Laboratory, Laurel, MD 20723 (United States); McComas, D. J. [Department of Astrophysical Sciences, Princeton University, NJ 08544 (United States); Li, G. [The Center for Space Plasma and Aeronomic Research (CSPAR), University of Alabama in Huntsville, Huntsville, AL 35756 (United States); Cohen, C. M. S.; Mewaldt, R. A. [California Institute of Technology, Pasadena, CA 91125 (United States); Smith, C. W., E-mail: mdesai@swri.edu [University of New Hampshire, 8 College Road, Durham NH 03824 (United States)

    2016-09-10

    We fit ∼0.1–500 MeV nucleon{sup −1} H–Fe spectra in 46 large solar energetic particle (SEP) events with the double power-law Band function to obtain a normalization constant, low- and high-energy parameters γ {sub a} and γ {sub b}, and break energy E {sub B}, and derive the low-energy spectral slope γ {sub 1}. We find that: (1) γ {sub a}, γ {sub 1}, and γ {sub b} are species-independent and the spectra steepen with increasing energy; (2) E {sub B} decreases systematically with decreasing Q/M scaling as (Q/M){sup α}; (3) α varies between ∼0.2–3 and is well correlated with the ∼0.16–0.23 MeV nucleon{sup −1} Fe/O; (4) in most events, α < 1.4, γ {sub b}– γ {sub a} > 3, and O E {sub B} increases with γ {sub b}– γ {sub a}; and (5) in many extreme events (associated with faster coronal mass ejections (CMEs) and GLEs), Fe/O and {sup 3}He/{sup 4}He ratios are enriched, α ≥ 1.4, γ {sub b}– γ {sub a} < 3, and E {sub B} decreases with γ {sub b}– γ {sub a}. The species-independence of γ {sub a}, γ {sub 1}, and γ {sub b} and the Q/M dependence of E {sub B} within an event and the α values suggest that double power-law SEP spectra occur due to diffusive acceleration by near-Sun CME shocks rather than scattering in interplanetary turbulence. Using γ {sub 1}, we infer that the average compression ratio for 33 near-Sun CME shocks is 2.49 ± 0.08. In most events, the Q/M dependence of E {sub B} is consistent with the equal diffusion coefficient condition and the variability in α is driven by differences in the near-shock wave intensity spectra, which are flatter than the Kolmogorov turbulence spectrum but weaker than the spectra for extreme events. In contrast, in extreme events, enhanced wave power enables faster CME shocks to accelerate impulsive suprathermal ions more efficiently than ambient coronal ions.

  15. Selective solar absorber coating research at the CSIR (South Africa)

    CSIR Research Space (South Africa)

    Roro, Kittessa T

    2011-05-01

    Full Text Available to deposit these C/NiO coatings on aluminum substrates. Preliminary optical results have shown absorptance of up to 90 %. The preparation and characterization as well as the process towards developing a large-area solar selective coating for low cost domestic...

  16. Influence of solvents on properties of solar selective coatings ...

    Indian Academy of Sciences (India)

    Influence of solvents on properties of solar selective coatings obtained by spray pyrolysis. MIHAELA DUDITA. ∗. , LUMINITA ISAC and ANCA DUTA. Renewable Energy Systems and Recycling Department, Transilvania University of Brasov, Eroilor 29,. 500 036 Brasov, Romania. MS received 9 September 2011; revised 10 ...

  17. Fabrication of selective solar absorbers using pulsed laser deposition

    CSIR Research Space (South Africa)

    Yalisi, B

    2009-06-01

    Full Text Available infrared region. Minimising thermal emittance implies that the device retains all the solar energy that it absorbs from the sun without releasing it in the form of heat, until it has been collected and delivered to where it is to be utilised. Selective...

  18. On the causes of spectral enhancements in solar wind power spectra

    Science.gov (United States)

    Unti, T.; Russell, C. T.

    1976-01-01

    Enhancements in power spectra of the solar-wind ion flux in the frequency neighborhood of 0.5 Hz had been noted by Unti et al. (1973). It was speculated that these were due to convected small-scale density irregularities. In this paper, 54 flux spectra calculated from OGO 5 data are examined. It is seen that the few prominent spectral peaks which occur were not generated by density irregularities, but were due to several different causes, including convected discontinuities and propagating transverse waves. A superposition of many spectra, however, reveals a moderate enhancement at a frequency corresponding to convected features with a correlation length of a proton gyroradius, consistent with the results of Neugebauer (1975).

  19. Accurate measurements of solar spectral irradiance between 4000-10000 cm-1

    Science.gov (United States)

    Elsey, J.; Coleman, M. D.; Gardiner, T.; Shine, K. P.

    2017-12-01

    The near-infrared solar spectral irradiance (SSI) is an important input into simulations of weather and climate; the distribution of energy throughout this region of the spectrum influences atmospheric heating rates and the global hydrological cycle through absorption and scattering by water vapour. Current measurements by a mixture of ground-based and space-based instruments show differences of around 10% in the 4000-7000 cm-1 region, with no resolution to this controversy in sight. This work presents observations of SSI taken using a ground-based Fourier Transform spectrometer between 4000-10000 cm-1 at a field site in Camborne, UK, with particular focus on a rigorously defined uncertainty budget. While there is good agreement between this work and the commonly-used ATLAS3 spectrum between 7000-10000 cm-1, the SSI is systematically lower by 10% than ATLAS3 between 4000-7000 cm-1, with no overlap within the k = 2 measurement uncertainties.

  20. GREENHOUSE PLASTIC FILMS CAPABLE OF MODIFYING THE SPECTRAL DISTRIBUTION OF SOLAR RADIATION

    Directory of Open Access Journals (Sweden)

    Evelia Schettini

    2010-03-01

    Full Text Available The aim of this paper was to investigate the radiometric properties of innovative covering films for protected cultivation capable of modifying the spectral distribution of the transmitted radiation and thus the vegetative activity. Two photoselective films, three photoluminescent films and one low-density polyethylene film were used as greenhouse coverings for cherry trees and peach trees, grown in pots. The photoselective films were characterised by a reduction of the R/FR ratio in comparison to the natural solar radiation. Tree growth parameters, such as the apical shoot of cherry trees and the shoot of peach trees, were monitored. Different responses to vegetative activities were observed under the films, depending on the species, with a higher shoots growth rate in the peach with respect to the cherry. The photoselective film characterised by the lowest R/FR ratio significantly enhanced the growth of cherry and peach trees in comparison to the trees cultivated under the other greenhouse films

  1. Geometric optimisation of an accurate cosine correcting optic fibre coupler for solar spectral measurement

    Science.gov (United States)

    Cahuantzi, Roberto; Buckley, Alastair

    2017-09-01

    Making accurate and reliable measurements of solar irradiance is important for understanding performance in the photovoltaic energy sector. In this paper, we present design details and performance of a number of fibre optic couplers for use in irradiance measurement systems employing remote light sensors applicable for either spectrally resolved or broadband measurement. The angular and spectral characteristics of different coupler designs are characterised and compared with existing state-of-the-art commercial technology. The new coupler designs are fabricated from polytetrafluorethylene (PTFE) rods and operate through forward scattering of incident sunlight on the front surfaces of the structure into an optic fibre located in a cavity to the rear of the structure. The PTFE couplers exhibit up to 4.8% variation in scattered transmission intensity between 425 nm and 700 nm and show minimal specular reflection, making the designs accurate and reliable over the visible region. Through careful geometric optimization near perfect cosine dependence on the angular response of the coupler can be achieved. The PTFE designs represent a significant improvement over the state of the art with less than 0.01% error compared with ideal cosine response for angles of incidence up to 50°.

  2. Small Pitch Transition-Edge Sensors with Broadband High Spectral Resolution for Solar Physics

    Science.gov (United States)

    Smith, S. J.; Adams, J. S.; Eckart, M. E.; Smith, Adams; Bailey, C. N.; Bandler, S. R.; Chevenak, J. A.; Finkbeiner, F. M.; Kelley, R. L.; Kilbourne, C. A.; hide

    2012-01-01

    We are developing small pitch transition-edge sensor (TES) X-ray detectors optimized for solar astronomy. These devices are fabricated on thick Si substrates with embedded Cu heat-sink layer. We use 35 x 35 square micrometers Mo/Au TESs with 4.5 micrometer thick Au absorbers. We have tested devices with different geometric absorber stem contact areas with the TES and surrounding substrate area. This allows us to investigate the loss of athermal phonons to the substrate. Results show a correlation between thc stem contact area and a broadening in the spectral line shape indicative of athermal phonon loss. When the contact area is minimized we have obtained exceptional broadband spectral resolution of 1.28 plus or minus 0.03 eV at an energy of 1.5 keV, 1.58 plus or minus 0.07 eV at 5.9 keV and 1.96 plus or minus 0.08 eV at 8 keV. The linearity in the measured gain scale is understood in the context of the longitudinal proximity effect from the electrical bias leads resulting in transition characteristics that are strongly dependent upon TES size.

  3. Sol–gel derived solar selective coatings on SS 321 substrates for solar thermal applications

    Energy Technology Data Exchange (ETDEWEB)

    Subasri, R., E-mail: subasri@arci.res.in; Soma Raju, K.R.C.; Reddy, D.S.; Hebalkar, Neha Y.; Padmanabham, G.

    2016-01-01

    Sol–gel derived multilayered solar selective coatings were generated on AISI SS 321 substrates using Ag-TiO{sub 2} as the cermet layer, titania and silica as the dielectric layers with high and low refractive indices respectively. The phase compositions of the individual layers were independently confirmed using grazing angle incidence X-ray diffraction, which was corroborated by X-ray photoelectron spectroscopic analysis. Thickness of the layers was measured using variable angle spectroscopic ellipsometry. The solar absorbance was measured over the UV–Vis-NIR wavelength range. Thermal emissivity was determined using FTIR spectroscopic analysis. The durability of the coatings was ascertained using accelerated corrosion testing methods as well as by measuring the optical properties after thermal cycling experiments. The promising nature of hexavalent chrome-free, environmental friendly, multilayered solar selective coating was ascertained with respect to amenability to scale-up. - Highlights: • Sol–gel derived multilayered solar selective coatings developed on SS321 • Solar absorptance and thermal emittance at par with toxic chrome coating • Thermal stability and corrosion resistance of coatings studied • Coating performance found to be promising for large scale applications • Scale-up amenability investigated by coating generation on 1 m tubes.

  4. Assessing the relationship between spectral solar irradiance and stratospheric ozone using Bayesian inference

    Directory of Open Access Journals (Sweden)

    Ball William T.

    2014-01-01

    Full Text Available We investigate the relationship between spectral solar irradiance (SSI and ozone in the tropical upper stratosphere. We find that solar cycle (SC changes in ozone can be well approximated by considering the ozone response to SSI changes in a small number of individual wavelength bands between 176 and 310 nm, operating independently of each other. Additionally, we find that the ozone varies approximately linearly with changes in the SSI. Using these facts, we present a Bayesian formalism for inferring SC SSI changes and uncertainties from measured SC ozone profiles. Bayesian inference is a powerful, mathematically self-consistent method of considering both the uncertainties of the data and additional external information to provide the best estimate of parameters being estimated. Using this method, we show that, given measurement uncertainties in both ozone and SSI datasets, it is not currently possible to distinguish between observed or modelled SSI datasets using available estimates of ozone change profiles, although this might be possible by the inclusion of other external constraints. Our methodology has the potential, using wider datasets, to provide better understanding of both variations in SSI and the atmospheric response.

  5. Results of Spectral Corona Observations in Solar Activity Cycles 17-24

    Science.gov (United States)

    Aliev, A. Kh.; Guseva, S. A.; Tlatov, A. G.

    2017-12-01

    The results of the work of the global observation network are considered, and a comparative analysis of the data of various coronal observatories is performed. The coronal activity index has been reconstructed for the period 1939-2016 based on the data of various observatories in Kislovodsk system. For this purpose, the corona daily intensity maps from the Sacramento Peak and Lomnický Štít observatories according to the Solar-Geophysical Data journal have been digitized; they supplement the data of other observatories. The homogeneity and continuity of the corona observations at the Kislovodsk station, including activity cycle 24, is confirmed. Unfortunately, the only observatory at present that continues observation of the spectral corona in Fe XIV 5303 Å and Fe XIV 6374 Å lines is the Kislovodsk astronomical station Mountain Astronomical Station (MAS) of the Central Astronomical Observatory, Russian Academy of Sciences (Pulkovo). The data on the combined corona in 5303 Å line are analyzed. It is shown that there is a high correlation of the intensity index of green corona with solar radiation measurements in the vacuum UV region. Data on the beginning of the new 25th activity cycle in the corona at high latitudes are presented.

  6. High-spectral-resolution Observations of the Solar Chromosphere and Corona

    Science.gov (United States)

    Pasachoff, Jay M.; Bruck, M. A.

    2007-05-01

    We continue to reduce high-spectral-resolution observations of the solar chromosphere from the Swedish 1-m Solar Telescope (SST) and TRACE; and, at the 29 March 2006 total solar eclipse, of the solar corona in the [Fe XIV] green line and the [Fe X] red line. (a) The SST observations in 2006 used the SOUP Lyot filter to observe H-alpha limb spicules in five positions with 128 milliangstrom resolution for velocity imaging with several cameras to allow restoration of even noisy images. One camera is near H-alpha, providing high S/N images for extracting wavefront information. The other is deliberately defocused for Phase Diversity information. We use Multi-Object Multi-Frame Blind Deconvolution (MOMFBD; momfbd.org), assisted by Michiel Van Noort and Mats Löfdahl (Royal Swedish Academy of Sciences) and the CfA Hinode center. Simultaneous TRACE observations show spicules in emission and, silhouetted against the EUV corona, in absorption. (b) Our Fabry-Perot 2006-eclipse coronal spectra were taken with David Rust's (JHUAPL) 0.16 angstrom Y-cut lithium-niobate filter. With Rust and Matthew Noble, the etalon was stepped across the red coronal line every 0.22 angstrom. We present the profile and Doppler shifts of the [Fe X] line. (c) We collected simultaneous 10 Hz observations in the red and green coronal lines at the 2006 eclipse, with the goal of detecting high-frequency intensity oscillations ( 1 Hz), which can be relevant to coronal heating, and to confirm previous results. We present FFT and wavelet analysis of the aligned data. We thank Bryce Babcock and Steven Souza (Williams) for their eclipse collaboration. We acknowledge grants NNG04GK44G, NNG04GE48G, and NN05GG75G from NASA Planetary Astronomy. The eclipse observations were supported by NSF grant ATM-0552116 from the Solar Terrrestrial Program of the Atmospheres Sciences Division. Additional eclipse support was received from National Geographic's Committee on Research and Exploration and Williams's Rob Spring

  7. Use of spectral decomposition technique for delineation of channels at Solar gas discovery, offshore West Nile Delta, Egypt

    Directory of Open Access Journals (Sweden)

    Adel A.A. Othman

    2016-03-01

    In this paper, spectral decomposition technique is applied to the imaging and mapping of bed thickness, geologic discontinuities and channel delineation at Solar discovery. From the study, two distinctively different channels (gas bearing “Red channel” and water bearing “Yellow channel” were delineated in the area, and are proven by the drilled well, and some stratigraphic features are identified.

  8. Reconstruction of the solar spectral UV irradiance for nowcasting of the middle atmosphere state on the basis of LYRA measurements

    Directory of Open Access Journals (Sweden)

    T. Egorova

    2008-06-01

    Full Text Available The LYRA instrument onboard ESA PROBA2 satellite will provide 6-hourly solar irradiance at the Lyman-alpha (121.6 nm and the Herzberg continuum (~200–220 nm wavelength range. Because the nowcasting of the neutral and ionic state of the middle atmosphere requires the solar irradiance for the wide spectral range (120–680 nm we have developed the statistical tool for the reconstruction of the full spectrum from the LYRA measurements. The accuracy of the reconstructed irradiance has been evaluated with 1-D transient radiative-convective model with neutral and ion chemistry using the daily solar spectral irradiance measured with SUSIM and SOLSTICE instruments onboard UARS satellite. We compared the results of transient 1-year long model simulations for 2000 driven by the observed and reconstructed solar irradiance and showed that the reconstruction of the full spectrum using linear regression equation based on the solar irradiance in two LYRA channels can be successfully used for nowcasting of the middle atmosphere. We have also identified conditions when the proposed approach does not yield spectral reconstruction with sufficient accuracy.

  9. An efficient method of wavelength interval selection based on random frog for multivariate spectral calibration

    Science.gov (United States)

    Yun, Yong-Huan; Li, Hong-Dong; Wood, Leslie R. E.; Fan, Wei; Wang, Jia-Jun; Cao, Dong-Sheng; Xu, Qing-Song; Liang, Yi-Zeng

    2013-07-01

    Wavelength selection is a critical step for producing better prediction performance when applied to spectral data. Considering the fact that the vibrational and rotational spectra have continuous features of spectral bands, we propose a novel method of wavelength interval selection based on random frog, called interval random frog (iRF). To obtain all the possible continuous intervals, spectra are first divided into intervals by moving window of a fix width over the whole spectra. These overlapping intervals are ranked applying random frog coupled with PLS and the optimal ones are chosen. This method has been applied to two near-infrared spectral datasets displaying higher efficiency in wavelength interval selection than others. The source code of iRF can be freely downloaded for academy research at the website: http://code.google.com/p/multivariate-calibration/downloads/list.

  10. New Instruments for Spectrally-Resolved Solar Soft X-ray Observations from CubeSats, and Larger Missions

    Science.gov (United States)

    Caspi, A.; Shih, A.; Warren, H. P.; DeForest, C. E.; Woods, T. N.

    2015-12-01

    Solar soft X-ray (SXR) observations provide important diagnostics of plasma heating, during solar flares and quiescent times. Spectrally- and temporally-resolved measurements are crucial for understanding the dynamics and evolution of these energetic processes; spatially-resolved measurements are critical for understanding energy transport. A better understanding of the thermal plasma informs our interpretation of hard X-ray (HXR) observations of nonthermal particles, improving our understanding of the relationships between particle acceleration, plasma heating, and the underlying release of magnetic energy during reconnection. We introduce a new proposed mission, the CubeSat Imaging X-ray Solar Spectrometer (CubIXSS), to measure spectrally- and spatially-resolved SXRs from the quiescent and flaring Sun from a 6U CubeSat platform in low-Earth orbit during a nominal 1-year mission. CubIXSS includes the Amptek X123-SDD silicon drift detector, a low-noise, commercial off-the-shelf (COTS) instrument enabling solar SXR spectroscopy from ~0.5 to ~30 keV with ~0.15 keV FWHM spectral resolution with low power, mass, and volume requirements. An X123-CdTe cadmium-telluride detector is also included for ~5-100 keV HXR spectroscopy with ~0.5-1 keV FWHM resolution. CubIXSS also includes a novel spectro-spatial imager -- the first ever solar imager on a CubeSat -- utilizing a pinhole aperture and X-ray transmission diffraction grating to provide full-Sun imaging from ~0.1 to ~10 keV, with ~25 arcsec and ~0.1 Å FWHM spatial and spectral resolutions, respectively. We discuss scaled versions of these instruments, with greater sensitivity and dynamic range, and significantly improved spectral and spatial resolutions for the imager, for deployment on larger platforms such as Small Explorer missions.

  11. Swarm intelligence based wavelet coefficient feature selection for mass spectral classification: an application to proteomics data.

    Science.gov (United States)

    Zhao, Weixiang; Davis, Cristina E

    2009-09-28

    This paper introduces the ant colony algorithm, a novel swarm intelligence based optimization method, to select appropriate wavelet coefficients from mass spectral data as a new feature selection method for ovarian cancer diagnostics. By determining the proper parameters for the ant colony algorithm (ACA) based searching algorithm, we perform the feature searching process for 100 times with the number of selected features fixed at 5. The results of this study show: (1) the classification accuracy based on the five selected wavelet coefficients can reach up to 100% for all the training, validating and independent testing sets; (2) the eight most popular selected wavelet coefficients of the 100 runs can provide 100% accuracy for the training set, 100% accuracy for the validating set, and 98.8% accuracy for the independent testing set, which suggests the robustness and accuracy of the proposed feature selection method; and (3) the mass spectral data corresponding to the eight popular wavelet coefficients can be located by reverse wavelet transformation and these located mass spectral data still maintain high classification accuracies (100% for the training set, 97.6% for the validating set, and 98.8% for the testing set) and also provide sufficient physical and medical meaning for future ovarian cancer mechanism studies. Furthermore, the corresponding mass spectral data (potential biomarkers) are in good agreement with other studies which have used the same sample set. Together these results suggest this feature extraction strategy will benefit the development of intelligent and real-time spectroscopy instrumentation based diagnosis and monitoring systems.

  12. Chromium Trioxide Hole-Selective Heterocontacts for Silicon Solar Cells.

    Science.gov (United States)

    Lin, Wenjie; Wu, Weiliang; Liu, Zongtao; Qiu, Kaifu; Cai, Lun; Yao, Zhirong; Ai, Bin; Liang, Zongcun; Shen, Hui

    2018-04-25

    A high recombination rate and high thermal budget for aluminum (Al) back surface field are found in the industrial p-type silicon solar cells. Direct metallization on lightly doped p-type silicon, however, exhibits a large Schottky barrier for the holes on the silicon surface because of Fermi-level pinning effect. As a result, low-temperature-deposited, dopant-free chromium trioxide (CrO x , x solar cell as a hole-selective contact at the rear surface. By using 4 nm CrO x between the p-type silicon and Ag, we achieve a reduction of the contact resistivity for the contact of Ag directly on p-type silicon. For further improvement, we utilize a CrO x (2 nm)/Ag (30 nm)/CrO x (2 nm) multilayer film on the contact between Ag and p-type crystalline silicon (c-Si) to achieve a lower contact resistance (40 mΩ·cm 2 ). The low-resistivity Ohmic contact is attributed to the high work function of the uniform CrO x film and the depinning of the Fermi level of the SiO x layer at the silicon interface. Implementing the advanced hole-selective contacts with CrO x /Ag/CrO x on the p-type silicon solar cell results in a power conversion efficiency of 20.3%, which is 0.1% higher than that of the cell utilizing 4 nm CrO x . Compared with the commercialized p-type solar cell, the novel CrO x -based hole-selective transport material opens up a new possibility for c-Si solar cells using high-efficiency, low-temperature, and dopant-free deposition techniques.

  13. Detection of plum pox virus infection in selection plum trees using spectral imaging

    Science.gov (United States)

    Angelova, Liliya; Stoev, Antoniy; Borisova, Ekaterina; Avramov, Latchezar

    2016-01-01

    Plum pox virus (PPV) is among the most studied viral diseases in the world in plants. It is considered to be one of the most devastating diseases of stone fruits in terms of agronomic impact and economic importance. Noninvasive, fast and reliable techniques are required for evaluation of the pathology in selection trees with economic impact. Such advanced tools for PPV detection could be optical techniques as light-induced fluorescence and diffuse reflectance spectroscopies. Specific regions in the electromagnetic spectra have been found to provide information about the physiological stress in plants, and consequently, diseased plants usually exhibit different spectral signature than non-stressed healthy plants in those specific ranges. In this study spectral reflectance and chlorophyll fluorescence were used for the identification of biotic stress caused by the pox virus on plum trees. The spectral responses of healthy and infected leaves from cultivars, which are widespread in Bulgaria were investigated. The two applied techniques revealed statistically significant differences between the spectral data of healthy plum leaves and those infected by PPV in the visible and near-infrared spectral ranges. Their application for biotic stress detection helps in monitoring diseases in plants using the different plant spectral properties in these spectral ranges. The strong relationship between the results indicates the applicability of diffuse reflectance and fluorescence techniques for conducting health condition assessments of vegetation and their importance for plant protection practices.

  14. Laser Process for Selective Emitter Silicon Solar Cells

    Directory of Open Access Journals (Sweden)

    G. Poulain

    2012-01-01

    Full Text Available Selective emitter solar cells can provide a significant increase in conversion efficiency. However current approaches need many technological steps and alignment procedures. This paper reports on a preliminary attempt to reduce the number of processing steps and therefore the cost of selective emitter cells. In the developed procedure, a phosphorous glass covered with silicon nitride acts as the doping source. A laser is used to open locally the antireflection coating and at the same time achieve local phosphorus diffusion. In this process the standard chemical etching of the phosphorous glass is avoided. Sheet resistance variation from 100 Ω/sq to 40 Ω/sq is demonstrated with a nanosecond UV laser. Numerical simulation of the laser-matter interaction is discussed to understand the dopant diffusion efficiency. Preliminary solar cells results show a 0.5% improvement compared with a homogeneous emitter structure.

  15. Estimation of spectral solar radiation based on global insolation and characteristics of spectral solar radiation on a tilt surface; Zenten nissharyo ni motozuku zenten nissha supekutoru no suitei to keishamen bunko tokusei

    Energy Technology Data Exchange (ETDEWEB)

    Baba, H.; Kanayama, K.; Endo, N.; Koromohara, K.; Takayama, H. [Kitami Institute of Technology, Hokkaido (Japan)

    1996-10-27

    Use of global insolation for estimating the corresponding spectral distribution is proposed. Measurements of global insolation spectrum throughout a year were compiled for clear days and cloudy days, ranked by 100W/m{sup 2}, for the clarification of spectral distribution. Global insolation quantity for a clear day was subject mainly to sun elevation. The global insolation spectral distribution with the sun elevation not lower than 15{degree} was similar to Bird`s model. Under the cloudy sky, energy density was lower in the region of wavelengths longer than the peak wavelength of 0.46{mu}m, and the distribution curve was sharper than that under the clear sky. Values given by Bird`s model were larger than measured values in the wavelength range of 0.6-1.8{mu}m, which was attributed to absorption by vapor. From the standard spectral distribution charts for the clear sky and cloudy sky, and from the dimensionless spectral distributions obtained by dividing them by the peak values, spectral distributions could be estimated of insolation quantities for the clear sky, cloudy sky, etc. As for the characteristics of spectral solar radiation on a tilt surface obtained from Bird`s model, they agreed with actually measured values at an angle of inclination of 60{degree} or smaller. 6 refs., 10 figs., 1 tab.

  16. Building-Integrated Solar Energy Devices based on Wavelength Selective Films

    Science.gov (United States)

    Ulavi, Tejas

    A potentially attractive option for building integrated solar is to employ hybrid solar collectors which serve dual purposes, combining solar thermal technology with either thin film photovoltaics or daylighting. In this study, two hybrid concepts, a hybrid photovoltaic/thermal (PV/T) collector and a hybrid 'solar window', are presented and analyzed to evaluate technical performance. In both concepts, a wavelength selective film is coupled with a compound parabolic concentrator (CPC) to reflect and concentrate the infrared portion of the solar spectrum onto a tubular absorber. The visible portion of the spectrum is transmitted through the concentrator to either a thin film Cadmium Telluride (CdTe) solar panel for electricity generation or into the interior space for daylighting. Special attention is given to the design of the hybrid devices for aesthetic building integration. An adaptive concentrator design based on asymmetrical truncation of CPCs is presented for the hybrid solar window concept. The energetic and spectral split between the solar thermal module and the PV or daylighting module are functions of the optical properties of the wavelength selective film and the concentrator geometry, and are determined using a Monte Carlo Ray-Tracing (MCRT) model. Results obtained from the MCRT can be used in conjugation with meteorological data for specific applications to study the impact of CPC design parameters including the half-acceptance angle thetac, absorber diameter D and truncation on the annual thermal and PV/daylighting efficiencies. The hybrid PV/T system is analyzed for a rooftop application in Phoenix, AZ. Compared to a system of the same area with independent solar thermal and PV modules, the hybrid PV/T provides 20% more energy, annually. However, the increase in total delivered energy is due solely to the addition of the thermal module and is achieved at an expense of a decrease in the annual electrical efficiency from 8.8% to 5.8% due to shading by

  17. Climate responses to SATIRE and SIM-based spectral solar forcing in a 3D atmosphere-ocean coupled GCM

    Directory of Open Access Journals (Sweden)

    Wen Guoyong

    2017-01-01

    Full Text Available We apply two reconstructed spectral solar forcing scenarios, one SIM (Spectral Irradiance Monitor based, the other the SATIRE (Spectral And Total Irradiance REconstruction modeled, as inputs to the GISS (Goddard Institute for Space Studies GCMAM (Global Climate Middle Atmosphere Model to examine climate responses on decadal to centennial time scales, focusing on quantifying the difference of climate response between the two solar forcing scenarios. We run the GCMAM for about 400 years with present day trace gas and aerosol for the two solar forcing inputs. We find that the SIM-based solar forcing induces much larger long-term response and 11-year variation in global averaged stratospheric temperature and column ozone. We find significant decreasing trends of planetary albedo for both forcing scenarios in the 400-year model runs. However the mechanisms for the decrease are very different. For SATIRE solar forcing, the decreasing trend of planetary albedo is associated with changes in cloud cover. For SIM-based solar forcing, without significant change in cloud cover on centennial and longer time scales, the apparent decreasing trend of planetary albedo is mainly due to out-of-phase variation in shortwave radiative forcing proxy (downwelling flux for wavelength >330 nm and total solar irradiance (TSI. From the Maunder Minimum to present, global averaged annual mean surface air temperature has a response of ~0.1 °C to SATIRE solar forcing compared to ~0.04 °C to SIM-based solar forcing. For 11-year solar cycle, the global surface air temperature response has 3-year lagged response to either forcing scenario. The global surface air 11-year temperature response to SATIRE forcing is about 0.12 °C, similar to recent multi-model estimates, and comparable to the observational-based evidence. However, the global surface air temperature response to 11-year SIM-based solar forcing is insignificant and inconsistent with observation-based evidence.

  18. Development of a very fast spectral response measurement system for analysis of hydrogenated amorphous silicon solar cells and modules

    International Nuclear Information System (INIS)

    Rodríguez, J.A.; Fortes, M.; Alberte, C.; Vetter, M.; Andreu, J.

    2013-01-01

    Highlights: ► Spectral response equipment for measuring a-Si:H solar cells in a few seconds. ► Equipment based on 16 LEDs with simultaneous illumination of the solar cell. ► The current generated by each LED is analyzed by a Fast Fourier Transform. ► Cheap equipment without lock-in technology for the current measurement. ► Measurement error vs. conventional measurement less than 1% in J sc . - Abstract: An important requirement for a very fast spectral response measurement system is the simultaneous illumination of the solar cell at multiple well defined wavelengths. Nowadays this can be done by means of light emitting diodes (LEDs) available for a multitude of wavelengths. For the purpose to measure the spectral response (SR) of amorphous silicon solar cells a detailed characterization of LEDs emitting in the wavelength range from 300 nm to 800 nm was performed. In the here developed equipment the LED illumination is modulated in the frequency range from 100 Hz to 200 Hz and the current generated by each LED is analyzed by a Fast Fourier Transform (FFT) to determine the current component corresponding to each wavelength. The equipment provides a signal to noise ratio of 2–4 orders of magnitude for individual wavelengths resulting in a precise measurement of the SR over the whole wavelength range. The difference of the short circuit current determined from the SR is less than 1% in comparison to a conventional system with monochromator.

  19. Cosensitization with Vat-Based Organic Dyes for Enhanced Spectral Response of Dye-Sensitized Solar Cells

    Science.gov (United States)

    Hosseinnezhad, Mozhgan

    2017-04-01

    Cosensitization using two organic dyes with supplementary absorption spectra on a photoelectrode is an effective method for improving the photovoltaic properties of dye-sensitized solar cells. Two organic dyes based on indigo and thioindigo have been synthesized, purified, and used to sensitize solar cells with spectral response extending across the entire visible region. To improve their photoelectric properties, different molar ratios were investigated, yielding total efficiency of 6.17% at dye 1:dye 2 = 4:6. The effect of the concentration of Cheno antiaggregation agent on the performance of the dye-sensitized solar cells was also considered. The results demonstrate that higher conversion efficiency ( η = 6.82%) was achieved with 10 × 10-3 M Cheno. Finally, the performance of cosensitized solar cells was measured at different temperatures between 10°C and 50°C. The results indicated that J sc decreased with increasing temperature, directly affecting the conversion efficiency.

  20. Optimisation of optical absorption properties of spectrally selective C-NiO composite coatings

    CSIR Research Space (South Africa)

    Tile, N

    2011-05-01

    Full Text Available and expensive. Carbon in Nickel Oxide (C-NiO) composite material has been found to have a very good spectral selectivity1,2. Moreover this material has a potential of low cost large scale fabrication since it can be fabricated by a simple sol-gel technique...

  1. Simultaneous Spectral-Spatial Feature Selection and Extraction for Hyperspectral Images.

    Science.gov (United States)

    Zhang, Lefei; Zhang, Qian; Du, Bo; Huang, Xin; Tang, Yuan Yan; Tao, Dacheng

    2018-01-01

    In hyperspectral remote sensing data mining, it is important to take into account of both spectral and spatial information, such as the spectral signature, texture feature, and morphological property, to improve the performances, e.g., the image classification accuracy. In a feature representation point of view, a nature approach to handle this situation is to concatenate the spectral and spatial features into a single but high dimensional vector and then apply a certain dimension reduction technique directly on that concatenated vector before feed it into the subsequent classifier. However, multiple features from various domains definitely have different physical meanings and statistical properties, and thus such concatenation has not efficiently explore the complementary properties among different features, which should benefit for boost the feature discriminability. Furthermore, it is also difficult to interpret the transformed results of the concatenated vector. Consequently, finding a physically meaningful consensus low dimensional feature representation of original multiple features is still a challenging task. In order to address these issues, we propose a novel feature learning framework, i.e., the simultaneous spectral-spatial feature selection and extraction algorithm, for hyperspectral images spectral-spatial feature representation and classification. Specifically, the proposed method learns a latent low dimensional subspace by projecting the spectral-spatial feature into a common feature space, where the complementary information has been effectively exploited, and simultaneously, only the most significant original features have been transformed. Encouraging experimental results on three public available hyperspectral remote sensing datasets confirm that our proposed method is effective and efficient.

  2. Synthesis and optical characterization of C-SiO2 and C-NiO sol-gel composite films for use as selective solar absorbers

    CSIR Research Space (South Africa)

    Makiwa, G

    2008-08-01

    Full Text Available The authors present a cheaper and environmentally friendly method to fabricate efficient spectrally selective solar absorber materials. The sol-gel technique was used to fabricate carbon-silica (C-SiO2) and carbon-nickel oxide (C-NiO) composite...

  3. Automatic endmember selection and nonlinear spectral unmixing of Lunar analog minerals

    Science.gov (United States)

    Rommel, Daniela; Grumpe, Arne; Felder, Marian Patrik; Wöhler, Christian; Mall, Urs; Kronz, Andreas

    2017-03-01

    While the interpretation of spectral reflectance data has been widely applied to detect the presence of minerals, determining and quantifying the abundances of minerals contained by planetary surfaces is still an open problem. With this paper we address one of the two main questions arising from the spectral unmixing problem. While the mathematical mixture model has been extensively researched, considerably less work has been committed to the selection of endmembers from a possibly huge database or catalog of potential endmembers. To solve the endmember selection problem we define a new spectral similarity measure that is not purely based on the reconstruction error, i.e. the squared difference between the modeled and the measured reflectance spectrum. To select reasonable endmembers, we extend the similarity measure by adding information extracted from the spectral absorption bands. This will allow for a better separation of spectrally similar minerals. Evaluating all possible subsets of a possibly very large catalog that contain at least one endmember leads to an exponential increase in computational complexity, rendering catalogs of 20-30 endmembers impractical. To overcome this computational limitation, we propose the usage of a genetic algorithm that, while initially starting with random subsets, forms new subsets by combining the best subsets and, to some extent, does a local search around the best subsets by randomly adding a few endmembers. A Monte-Carlo simulation based on synthetic mixtures and a catalog size varying from three to eight endmembers demonstrates that the genetic algorithm is expected to require less combinations to be evaluated than an exhaustive search if the catalog comprises 10 or more endmembers. Since the genetic algorithm evaluates some combinations multiple times, we propose a simple modification and store previously evaluated endmember combinations. The resulting algorithm is shown to never require more function evaluations than a

  4. Determination of tropospheric aerosol characteristics by spectral measurements of solar radiation using a compact, stand-alone spectroradiometer.

    Science.gov (United States)

    Manago, Naohiro; Kuze, Hiroaki

    2010-03-10

    We developed a method for characterizing atmospheric properties from ground-based, spectral measurements of direct and scattered solar radiation under clear sky conditions. A compact spectroradiometer is employed for radiation measurement in the wavelength range between 350 and 1050 nm with a resolution of 10 nm. Spectral matching of measured and simulated spectra yields a set of optical parameters that describe optical characteristics of tropospheric aerosols. We utilize the radiative transfer code MODTRAN4 for constructing realistic atmospheric models. Details of the system calibration, analysis procedure, and the results of its performance test are described.

  5. Selective emitter using porous silicon for crystalline silicon solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Moon, Inyong; Kim, Kyunghae; Kim, Youngkuk; Han, Kyumin; Kyeong, Doheon; Kwon, Taeyoung; Vinh Ai, Dao; Lee, Jeongchul; Yi, Junsin [School of Information and Communication Engineering, Sungkyunkwan University, Chunchun-dong, Jangan-Gu, Suwon-City, Kyunggi-Do 440-746 (Korea); Thamilselvan, M. [School of Information and Communication Engineering, Sungkyunkwan University, Chunchun-dong, Jangan-Gu, Suwon-City, Kyunggi-Do 440-746 (Korea); Government College of Technology, Coimbatore, Tamilnadu (India); Ju, Minkyu; Lee, Kyungsoo [KPE Ins. Chunchun-dong, Jangan-Gu, Suwon-City, Kyunggi-Do 440-746 (Korea)

    2009-06-15

    This study is devoted to the formation of high-low-level-doped selective emitter for crystalline silicon solar cells for photovoltaic application. We report here the formation of porous silicon under chemical reaction condition. The chemical mixture containing hydrofluoric and nitric acid, with de-ionized water, was used to make porous on the half of the silicon surface of size 125 x 125 cm. Porous and non-porous areas each share half of the whole silicon surface. H{sub 3}PO{sub 4}:methanol gives the best deposited layer with acceptable adherence and uniformity on the non-porous and porous areas of the silicon surface to get high- and low-level-doped regions. The volume concentration of H{sub 3}PO{sub 4} does not exceed 10% of the total volume emulsion. Phosphoric acid was used as an n-type doping source to make emitter for silicon solar cells. The measured emitter sheet resistances at the high- and low-level-doped regions were 30-35 and 97-474 {omega}/{open_square} respectively. A simple process for low- and high-level doping has been achieved by forming porous and porous-free silicon surface, in this study, which could be applied for solar cells selective emitter doping. (author)

  6. Ultraviolet spectral distribution and erythema-weighted irradiance from indoor tanning devices compared with solar radiation exposures.

    Science.gov (United States)

    Sola, Yolanda; Baeza, David; Gómez, Miguel; Lorente, Jerónimo

    2016-08-01

    Concern regarding the impact of indoor tanning devices on human health has led to different regulations and recommendations, which set limits on erythema-weighted irradiance. Here, we analyze spectral emissions from 52 tanning devices in Spanish facilities and compare them with surface solar irradiance for different solar zenith angles. Whereas most of the devices emitted less UV-B radiation than the midday summer sun, the unweighted UV-A irradiance was 2-6 times higher than solar radiation. Moreover, the spectral distributions of indoor devices were completely different from that of solar radiation, differing in one order of magnitude at some UV-A wavelengths, depending on the lamp characteristics. In 21% of the devices tested, the erythema-weighted irradiance exceeded 0.3Wm(-2): the limit fixed by the European standard and the Spanish regulation. Moreover, 29% of the devices fall within the UV type 4 classification, for which medical advice is required. The high variability in erythema-weighted irradiance results in a wide range of exposure times to reach 1 standard erythemal dose (SED: 100Jm(-2)), with 62% of devices requiring exposures of solar UV-A dose. Copyright © 2016 Elsevier B.V. All rights reserved.

  7. A Comprehensive Study of Chelyabinsk Meteorite: Physical, Mineralogical, Spectral Properties and Solar System Orbit

    Science.gov (United States)

    Gritsevich, Maria; Kohout, T.; Grokhovsky, V.; Yakovlev, G.; Lyytinen, E.; Vinnikov, V.; Haloda, J.; Halodova, P.; Michallik, R.; Penttilä, A.; Muinonen, K.; Peltoniemi, J.; Lupovka, V.; Dmitriev, V.

    2013-10-01

    On February 15, 2013, at 9:22 am, an exceptionally bright and long duration fireball was observed by many eyewitnesses in the Chelyabinsk region, Russia. A strong shock wave associated with the fireball caused significant damage such as destroyed windows and parts of buildings in Chelyabinsk and the surrounding territories. A number of video records of the event are available and have been used to reconstruct atmospheric trajectory, velocity, deceleration rate, and parent asteroid Apollo-type orbit in the Solar System. Two types of meteorite material are present among recovered fragments of the Chelyabinsk meteorite. These are described as the light-colored and dark-colored lithology. Both types are of LL5 composition with the dark-colored one being an impact-melt shocked to a higher level. Based on the magnetic susceptibility measurements, the Chelyabinsk meteorite is richer in metallic iron as compared to other LL chondrites. The measured bulk and grain densities and the porosity closely resemble other LL chondrites. Shock darkening does not have a significant effect on the material physical properties, but causes a decrease of reflectance and decrease in silicate absorption bands in the reflectance spectra. This is similar to the space weathering effects observed on asteroids. However, no spectral slope change similar to space weathering is observed as a result of shock-darkening. Thus, it is possible that some dark asteroids with invisible silicate absorption bands may be composed of relatively fresh shock darkened chondritic material.

  8. Broad-band spectral studies of optical lightnings and possible correlation with solar activity

    International Nuclear Information System (INIS)

    Bhat, C.L.; Sapru, M.L.; Kaul, R.K.; Razdan, H.

    1984-01-01

    Optical pulses from lightning discharges have been recorded in a ground-based experiment, meant primarily for the detection of cosmic X- and γ-ray bursts through the atmospheric fluorescence technique. It is shown that the spectral ratio Asub(v)/Asub(y), i.e. the ratio of pulse amplitudes in the violet to that in yellow wavelength bands (3400-4300 A and 4400-6000 A respectively) provides a good indication of the lightning channel temperature, the range of derived temperatures extending from 5.000 K to 60.000 K. Based on the distribution of observed Asub(v)/Asub(y) values on a daily basis, it has been possible to separate the observed lightning activity into two classes. One class of event is shown to be correlated with the peaking of the global atmospheric electric field and occurs preferentially on days when the ground-level cosmic ray intensity shows a significant decrease in association with an increase in geomagnetic activity. The results are discussed in terms of the contemporary views regarding solar control of atmospheric electricity and the various sun-weather correlations reported earlier. (author)

  9. High spectral resolution measurements of a solar flare hard X-ray burst

    International Nuclear Information System (INIS)

    Lin, R.P.; Schwartz, R.A.; NASA, Goddard Space Flight Center, Greenbelt, MD)

    1987-01-01

    Observations are reported of an intense solar flare hard X-ray burst on June 27, 1980, made with a balloon-borne array of liquid nitrogen-cooled Ge detector which provided unprecedented spectral resolution (no more than 1 keV FWHM). The hard X-ray spectra throughout the impulsive phase burst fitted well to a double power-law form, and emission from an isothermal 0.1-1 billion K plasma can be specifically excluded. The temporal variations of the spectrum indicate that the hard X-ray burst is made up of two superposed components: individual spikes lasting about 3-15 sec, which have a hard spectrum and a break energy of 30-65 keV; and a slowly varying component characterized by a soft spectrum with a constant low-energy slope and a break energy which increases from 25 kev to at least 100 keV through the event. The double power-law shape indicates that DC electric field acceleration, similar to that occurring in the earth's auroral zone, may be the source of the energetic electrons which produce the hard X-ray emission. 39 references

  10. A New SATIRE-S Spectral Solar Irradiance Reconstruction for Solar Cycles 21-23 and Its Implications for Stratospheric Ozone*

    Science.gov (United States)

    Ball, William T.; Krivova, Natalie A.; Unruh, Yvonne C.; Haigh, Joanna D.; Solanki, Sami K.

    2014-11-01

    We present a revised and extended total and spectral solar irradiance (SSI) reconstruction, which includes a wavelength-dependent uncertainty estimate, spanning the last three solar cycles using the SATIRE-S model. The SSI reconstruction covers wavelengths between 115 and 160,000 nm and all dates between August 1974 and October 2009. This represents the first full-wavelength SATIRE-S reconstruction to cover the last three solar cycles without data gaps and with an uncertainty estimate. SATIRE-S is compared with the NRLSSI model and SORCE/SOLSTICE ultraviolet (UV) observations. SATIRE-S displays similar cycle behaviour to NRLSSI for wavelengths below 242 nm and almost twice the variability between 242 and 310 nm. During the decline of last solar cycle, between 2003 and 2008, SSI from SORCE/SOLSTICE version 12 and 10 typically displays more than three times the variability of SATIRE-S between 200 and 300 nm. All three datasets are used to model changes in stratospheric ozone within a 2D atmospheric model for a decline from high solar activity to solar minimum. The different flux changes result in different modelled ozone trends. Using NRLSSI leads to a decline in mesospheric ozone, while SATIRE-S and SORCE/SOLSTICE result in an increase. Recent publications have highlighted increases in mesospheric ozone when considering version 10 SORCE/SOLSTICE irradiances. The recalibrated SORCE/SOLSTICE version 12 irradiances result in a much smaller mesospheric ozone response than when using version 10 and now similar in magnitude to SATIRE-S. This shows that current knowledge of variations in spectral irradiance is not sufficient to warrant robust conclusions concerning the impact of solar variability on the atmosphere and climate.

  11. Aerosol Characterization at PSA from Spectral and Broadband Measurements of Solar Radiation; Caracterizacion de los Aerosoles en la PSA a partir de Medidas Espectrales y de Banda Ancha de Radiacion Solar

    Energy Technology Data Exchange (ETDEWEB)

    Salvador, P.; Polo, J.; Campos, A.; Espinar, B.

    2006-07-01

    When passing through the atmosphere, the solar radiation suffers extinction processes with and intensity that depends on the atmosphere state. Some of the attenuation mechanisms, in particular those oflicht scattering, are spectrally selective, and thus, the solar spectrum at the earth's surface can change drastically from one place to another. This fact can be used on the determination of some of the Earth atmosphere components. The case of aerosol turbidity has a particular interest due to its high variability. In mis work different methodologies for aerosol characterization are presented, Aerosol optical depth, turbidity and Angstrom exponent are determined by them. Moreover, a comparison among the different methods is established and two heat haze events occurring during summer in PSA (Tabernas) are analyzed. (Author) 18 refs.

  12. CO-ANALYSIS OF SOLAR MICROWAVE AND HARD X-RAY SPECTRAL EVOLUTIONS. I. IN TWO FREQUENCY OR ENERGY RANGES

    International Nuclear Information System (INIS)

    Song Qiwu; Huang Guangli; Nakajima, Hiroshi

    2011-01-01

    Solar microwave and hard X-ray spectral evolutions are co-analyzed in the 2000 June 10 and 2002 April 10 flares, and are simultaneously observed by the Owens-Valley Solar Array in the microwave band and by Yohkoh/Hard X-ray Telescope or RHESSI in the hard X-ray band, with multiple subpeaks in their light curves. The microwave and hard X-ray spectra are fitted by a power law in two frequency ranges of the optical thin part and two photon energy ranges, respectively. Similar to an earlier event in Shao and Huang, the well-known soft-hard-soft pattern of the lower energy range changed to the hard-soft-hard (HSH) pattern of the higher energy range during the spectral evolution of each subpeak in both hard X-ray flares. This energy dependence is actually supported by a positive correlation between the overall light curves and spectral evolution in the lower energy range, while it becomes an anti-correlation in the higher energy range. Regarding microwave data, the HSH pattern appears in the spectral evolution of each subpeak in the lower frequency range, which is somewhat similar to Huang and Nakajima. However, it returns back to the well-known pattern of soft-hard-harder for the overall spectral evolution in the higher frequency range of both events. This frequency dependence is confirmed by an anti-correlation between the overall light curves and spectral evolution in the lower frequency range, but it becomes a positive correlation in the higher frequency range. The possible mechanisms are discussed, respectively, for reasons why hard X-ray and microwave spectral evolutions have different patterns in different energy and frequency intervals.

  13. Large-Scale Nanophotonic Solar Selective Absorbers for High-Efficiency Solar Thermal Energy Conversion.

    Science.gov (United States)

    Li, Pengfei; Liu, Baoan; Ni, Yizhou; Liew, Kaiyang Kevin; Sze, Jeff; Chen, Shuo; Shen, Sheng

    2015-08-19

    An omnidirectional nanophotonic solar selective absorber is fabricated on a large scale using a template-stripping method. The nanopyramid nickel structure achieves an average absorptance of 95% at a wavelength range below 1.3 μm and a low emittance less than 10% at wavelength >2.5 μm. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. Leds used as spectral selective light detectors in remote sensing techniques

    International Nuclear Information System (INIS)

    Weber, C; Tocho, J O; Rodriguez, E J; Acciaresi, H A

    2011-01-01

    Remote sensing has been commonly considered as an effective technique in developing precision agriculture tools. Ground based and satellite spectral sensors have wide uses to retrieve remotely quantitative biophysical and biochemical characteristics of vegetation canopies as well as vegetation ground cover. Usually in-field remote sensing technologies use either a combination of interferential filters and photodiodes or different compact spectrometers to separate the spectral regions of interest. In this paper we present a new development of a sensor with LEDs used as spectrally selective photodetectors. Its performance was compared with a photodiode-filter sensor used in agronomic applications. Subsequent measurements of weed cover degree were performed and compared with other methodologies. Results show that the new LEDs based sensor has similar features that conventional ones to determining the weed soil cover degree; while LEDs based sensor has comparative advantages related its very low manufacturing cost and its robustness compatible with agricultural field applications.

  15. Selective suppression of high-order harmonics within phase-matched spectral regions.

    Science.gov (United States)

    Lerner, Gavriel; Diskin, Tzvi; Neufeld, Ofer; Kfir, Ofer; Cohen, Oren

    2017-04-01

    Phase matching in high-harmonic generation leads to enhancement of multiple harmonics. It is sometimes desired to control the spectral structure within the phase-matched spectral region. We propose a scheme for selective suppression of high-order harmonics within the phase-matched spectral region while weakly influencing the other harmonics. The method is based on addition of phase-mismatched segments within a phase-matched medium. We demonstrate the method numerically in two examples. First, we show that one phase-mismatched segment can significantly suppress harmonic orders 9, 15, and 21. Second, we show that two phase-mismatched segments can efficiently suppress circularly polarized harmonics with one helicity over the other when driven by a bi-circular field. The new method may be useful for various applications, including the generation of highly helical bright attosecond pulses.

  16. Simulation for spectral response of solar-blind AlGaN based p-i-n photodiodes

    Science.gov (United States)

    Xue, Shiwei; Xu, Jintong; Li, Xiangyang

    2015-04-01

    In this article, we introduced how to build a physical model of refer to the device structure and parameters. Simulations for solar-blind AlGaN based p-i-n photodiodes spectral characteristics were conducted in use of Silvaco TCAD, where device structure and parameters are comprehensively considered. In simulation, the effects of polarization, Urbach tail, mobility, saturated velocities and lifetime in AlGaN device was considered. Especially, we focused on how the concentration-dependent Shockley-Read-Hall (SRH) recombination model affects simulation results. By simulating, we analyzed the effects in spectral response caused by TAUN0 and TAUP0, and got the values of TAUN0 and TAUP0 which can bring a result coincides with test results. After that, we changed their values and made the simulation results especially the part under 255 nm performed better. In conclusion, the spectral response between 200 nm and 320 nm of solar-blind AlGaN based p-i-n photodiodes were simulated and compared with test results. We also found that TAUN0 and TAUP0 have a large impact on spectral response of AlGaN material.

  17. Solution-Processed Environmentally Friendly Ag2S Colloidal Quantum Dot Solar Cells with Broad Spectral Absorption

    Directory of Open Access Journals (Sweden)

    Viktor A. Öberg

    2017-10-01

    Full Text Available A facile heat-up synthesis route is used to synthesize environmentally friendly Ag2S colloidal quantum dots (CQDs that are applied as light absorbing material in solid state p-i-n junction solar cell devices. The as-synthesized Ag2S CQDs have an average size of around 3.5 nm and exhibit broad light absorption covering ultraviolet, visible, and near infrared wavelength regions. The solar cell devices are constructed with a device architecture of FTO/TiO2/Ag2S CQDs/hole transport material (HTM /Au using a solution-processed approach. Different HTMs, N2,N2,N2′,N2′,N7,N7,N7′,N7′-octakis(4-methoxyphenyl-9,9′-spirobi(9H-fluorene-2,2′,7,7′ tetramine (spiro-OMeTAD, poly(3-hexylthiophene-2,5-diyl (P3HT, and poly((2,3-bis(3-octyloxyphenyl-5,8-quinoxalinediyl-2,5-thiophenediyl TQ1 are studied for maximizing the device photovoltaic performance. The solar cell device with P3HT as a hole transport material gives the highest performance and the solar cell exhibit broad spectral absorption. These results indicate that Ag2S CQD have high potential for utilization as environmentally friendly light absorbing materials for solar cell application and that the hole transport material is critical to maximize the solar cell photovoltaic performance.

  18. Spectral Dependent Degradation of the Solar Diffuser on Suomi-NPP VIIRS Due to Surface Roughness-Induced Rayleigh Scattering

    Directory of Open Access Journals (Sweden)

    Xi Shao

    2016-03-01

    Full Text Available The Visible Infrared Imaging Radiometer Suite (VIIRS onboard Suomi National Polar Orbiting Partnership (SNPP uses a solar diffuser (SD as its radiometric calibrator for the reflective solar band calibration. The SD is made of Spectralon™ (one type of fluoropolymer and was chosen because of its controlled reflectance in the Visible/Near-Infrared/Shortwave-Infrared region and its near-Lambertian reflectance property. On-orbit changes in VIIRS SD reflectance as monitored by the Solar Diffuser Stability Monitor showed faster degradation of SD reflectance for 0.4 to 0.6 µm channels than the longer wavelength channels. Analysis of VIIRS SD reflectance data show that the spectral dependent degradation of SD reflectance in short wavelength can be explained with a SD Surface Roughness (length scale << wavelength based Rayleigh Scattering (SRRS model due to exposure to solar UV radiation and energetic particles. The characteristic length parameter of the SD surface roughness is derived from the long term reflectance data of the VIIRS SD and it changes at approximately the tens of nanometers level over the operational period of VIIRS. This estimated roughness length scale is consistent with the experimental result from radiation exposure of a fluoropolymer sample and validates the applicability of the Rayleigh scattering-based model. The model is also applicable to explaining the spectral dependent degradation of the SDs on other satellites. This novel approach allows us to better understand the physical processes of the SD degradation, and is complementary to previous mathematics based models.

  19. Estimates of leaf area index from spectral reflectance of wheat under different cultural practices and solar angle

    Science.gov (United States)

    Asrar, G.; Kanemasu, E. T.; Yoshida, M.

    1985-01-01

    The influence of management practices and solar illumination angle on the leaf area index (LAI) was estimated from measurements of wheat canopy reflectance evaluated by two methods, a regression formula and an indirect technique. The date of planting and the time of irrigation in relation to the stage of plant growth were found to have significant effects on the development of leaves in spring wheat. A reduction in soil moisture adversely affected both the duration and magnitude of the maximum LAI for late planting dates. In general, water stress during vegetative stages resulted in a reduction in maximum LAI, while water stress during the reproductive period shortened the duration of green LAI in spring wheat. Canopy geometry and solar angle also affected the spectral properties of the canopies, and hence the estimated LAI. Increase in solar zenith angles resulted in a general increase in estimated LAI obtained from both methods.

  20. Multicriteria analysis in selecting the optimal variant of solar system

    Directory of Open Access Journals (Sweden)

    Radziejowska Aleksandra

    2016-01-01

    Full Text Available Alternative energy sources are becoming more serious competition to traditional ways of generating energy. It becomes real integration of eco-energy with ecology, as well as the innovative technologies with low-energy construction. Apart from the cost an important issue are technical parameters of the equipment, durability, ease of installation, etc. The investor therefore is facing with the problem of decision-making to choose the best solution from the point of view of many criteria. In the article, the authors present the proposal to apply the methods of multi-criteria analysis to select the most beneficial variant of the solar system solutions. In this purpose will be use among other method: multivariate analysis of Saaty’s AHP, the taxonomic method of weighting factors and, belonging to a group of methods using outranking relations, the Promethee II method. Proposed comparative analysis can be used as a method for decision support during the selection of the most beneficial technological solution of solar installation and to evaluate operational efficiency existing buildings which will have implemented new systems.

  1. Energy and spectral efficiency analysis for selective ARQ multi-channel systems

    KAUST Repository

    Shafique, Taniya

    2017-07-31

    In this paper, we develop selective retransmission schemes for multiple-channel systems. The proposed schemes are selective automatic repeat request with fixed bandwidth (SARQ-FB), selective chase combining with fixed bandwidth (SCC-FB) and selective automatic repeat request with variable bandwidth (SARQ-VB). The main objective of the proposed schemes is to use the available power and bandwidth budget effectively along with the selective retransmission to deliver the required data successfully within a limited number of transmissions. To investigate the performance of each scheme, we first analyze the average spectral and energy efficiency and derive closed form expressions for each scheme. Then, we compare the EE and SE of each scheme through numerical results.

  2. Spectral Quantitative Analysis Model with Combining Wavelength Selection and Topology Structure Optimization

    Directory of Open Access Journals (Sweden)

    Qian Wang

    2016-01-01

    Full Text Available Spectroscopy is an efficient and widely used quantitative analysis method. In this paper, a spectral quantitative analysis model with combining wavelength selection and topology structure optimization is proposed. For the proposed method, backpropagation neural network is adopted for building the component prediction model, and the simultaneousness optimization of the wavelength selection and the topology structure of neural network is realized by nonlinear adaptive evolutionary programming (NAEP. The hybrid chromosome in binary scheme of NAEP has three parts. The first part represents the topology structure of neural network, the second part represents the selection of wavelengths in the spectral data, and the third part represents the parameters of mutation of NAEP. Two real flue gas datasets are used in the experiments. In order to present the effectiveness of the methods, the partial least squares with full spectrum, the partial least squares combined with genetic algorithm, the uninformative variable elimination method, the backpropagation neural network with full spectrum, the backpropagation neural network combined with genetic algorithm, and the proposed method are performed for building the component prediction model. Experimental results verify that the proposed method has the ability to predict more accurately and robustly as a practical spectral analysis tool.

  3. Development of a very fast spectral response measurement system for analysis of hydrogenated amorphous silicon solar cells and modules

    Energy Technology Data Exchange (ETDEWEB)

    Rodriguez, J.A., E-mail: jose.rodriguez@tsolar.eu [Dept. Technology, Development and Innovation, T-Solar Global S.A., Parque Tecnologico de Galicia, Avda. de Vigo 5, E-32900 San Cibrao das Vinas (Ourense) (Spain); Fortes, M. [Departamento de Electronica e Computacion, Universidade de Santiago de Compostela, 15782 Santiago de Compostela (Spain); Alberte, C.; Vetter, M.; Andreu, J. [Dept. Technology, Development and Innovation, T-Solar Global S.A., Parque Tecnologico de Galicia, Avda. de Vigo 5, E-32900 San Cibrao das Vinas (Ourense) (Spain)

    2013-01-01

    Highlights: Black-Right-Pointing-Pointer Spectral response equipment for measuring a-Si:H solar cells in a few seconds. Black-Right-Pointing-Pointer Equipment based on 16 LEDs with simultaneous illumination of the solar cell. Black-Right-Pointing-Pointer The current generated by each LED is analyzed by a Fast Fourier Transform. Black-Right-Pointing-Pointer Cheap equipment without lock-in technology for the current measurement. Black-Right-Pointing-Pointer Measurement error vs. conventional measurement less than 1% in J{sub sc}. - Abstract: An important requirement for a very fast spectral response measurement system is the simultaneous illumination of the solar cell at multiple well defined wavelengths. Nowadays this can be done by means of light emitting diodes (LEDs) available for a multitude of wavelengths. For the purpose to measure the spectral response (SR) of amorphous silicon solar cells a detailed characterization of LEDs emitting in the wavelength range from 300 nm to 800 nm was performed. In the here developed equipment the LED illumination is modulated in the frequency range from 100 Hz to 200 Hz and the current generated by each LED is analyzed by a Fast Fourier Transform (FFT) to determine the current component corresponding to each wavelength. The equipment provides a signal to noise ratio of 2-4 orders of magnitude for individual wavelengths resulting in a precise measurement of the SR over the whole wavelength range. The difference of the short circuit current determined from the SR is less than 1% in comparison to a conventional system with monochromator.

  4. A review of the concentrated photovoltaic/thermal (CPVT) hybrid solar systems based on the spectral beam splitting technology

    International Nuclear Information System (INIS)

    Ju, Xing; Xu, Chao; Han, Xue; Du, Xiaoze; Wei, Gaosheng; Yang, Yongping

    2017-01-01

    Highlights: • A review on spectral beam splitting (SBS) CPVT technologies is presented. • SBS methods including interference, liquid absorptive and other filters are discussed. • The researches of SBS CPVTs are reviewed comprehensively and summarized. • Recent research status and system performance characteristics are analysed. • Suggestions on the development of SBS CPVT technologies are proposed. - Abstract: This article presents a review on the research and development of spectral beam splitting concentrated photovoltaic/thermal (SBS CPVT) hybrid solar systems. The investigations on the SBS CPVT hybrid technologies had begun in the 1980s and were aimed at complete utilization of the solar irradiation over the whole solar spectrum using both PV cells and thermal absorbers. Several different SBS approaches were employed to achieve better conversion efficiencies, including the interference filter, liquid absorptive filter, holographic filter, luminescent filter, diffractive filter, combined interference and liquid absorptive filter, combined liquid and solid absorptive filter, and photovoltaics itself as a solid absorptive filter. The SBS CPVT systems were proposed or assembled in various system configurations for numerous purposes, such as domestic hot water, thermochemical reaction, hydrogen production, or even power generation. These researches and developments are comprehensively reviewed in this article, and the advantages and disadvantages of different SBS methods are presented and concluded. This paper also aims to provide a global point of view on research trends, market potential, technical obstacles, and the future work required for the development of SBS CPVT technology.

  5. High-Selectivity Filter Banks for Spectral Analysis of Music Signals

    Directory of Open Access Journals (Sweden)

    Luiz W. P. Biscainho

    2007-01-01

    Full Text Available This paper approaches, under a unified framework, several algorithms for the spectral analysis of musical signals. Such algorithms include the fast Fourier transform (FFT, the fast filter bank (FFB, the constant-Q transform (CQT, and the bounded-Q transform (BQT, previously known from the associated literature. Two new methods are then introduced, namely, the constant-Q fast filter bank (CQFFB and the bounded-Q fast filter bank (BQFFB, combining the positive characteristics of the previously mentioned algorithms. The provided analyses indicate that the proposed BQFFB achieves an excellent compromise between the reduced computational effort of the FFT, the high selectivity of each output channel of the FFB, and the efficient distribution of frequency channels associated to the CQT and BQT methods. Examples are included to illustrate the performances of these methods in the spectral analysis of music signals.

  6. Fourier-Transform Photocurrent Spectroscopy for a fast and highly sensitive spectral characterization of organic and hybrid solar cells

    International Nuclear Information System (INIS)

    Vandewal, K.; Goris, L.; Haeldermans, I.; Nesladek, M.; Haenen, K.; Wagner, P.; Manca, J.V.

    2008-01-01

    Two modes of Fourier-Transform Photocurrent Spectroscopy (FTPS) are presented for a fast and sensitive determination of photocurrent spectra of organic and dye sensitized solar cells. Furthermore, FTPS allows to spectrally resolve sub-bandgap absorption phenomena in P3HT, in organic P3HT:PCBM bulk heterojunctions and in hybrid P3HT/TiO 2 solar cells. The sub-bandgap absorption in the P3HT:PCBM blend is dominated by a band due to the formation of a ground-state charge-transfer complex between the polymer and PCBM. In P3HT/TiO 2 junctions such a charge-transfer complex band is not observed. Long-lived light induced sub-bandgap states appear in pure P3HT and in P3HT/TiO 2 junctions after irradiation with E > 1.9 eV

  7. Radiative heat transfer enhancement using geometric and spectral control for achieving high-efficiency solar-thermophotovoltaic systems

    Science.gov (United States)

    Kohiyama, Asaka; Shimizu, Makoto; Yugami, Hiroo

    2018-04-01

    We numerically investigate radiative heat transfer enhancement using spectral and geometric control of the absorber/emitter. A high extraction of the radiative heat transfer from the emitter as well as minimization of the optical losses from the absorber leads to high extraction and solar thermophotovoltaic (STPV) system efficiency. The important points for high-efficiency STPV design are discussed for the low and high area ratio of the absorber/emitter. The obtained general guideline will support the design of various types of STPV systems.

  8. Spectral properties of water ice and contaminants. [of importance to remote sensing of ice in solar system

    Science.gov (United States)

    Lucey, P. G.; Clark, R. N.

    1985-01-01

    For remote sensing studies of ices in the solar system, it is important to understand the optical properties of water ice, and mixtures of ice and particulate materials. The present paper has the objective to review the current understanding of the spectral properties of ice, and mixtures of ice and particulates. The review is to provide a basis for the understanding of the remote sensing of ice. It is found that reflectance spectra of ice-soil intimate mixtures are complex, nonlinear functions of the optical and physical properties of the components which comprise the surface.

  9. Laser nanostructured Co nanocylinders-Al{sub 2}O{sub 3} cermets for enhanced & flexible solar selective absorbers applications

    Energy Technology Data Exchange (ETDEWEB)

    Karoro, A., E-mail: angela@tlabs.ac.za [UNESCO-UNISA Africa Chair in Nanosciences-Nanotechnology, College of Graduate Studies, University of South Africa, Muckleneuk ridge, PO Box 392, Pretoria (South Africa); Nanosciences African Network (NANOAFNET), iThemba LABS-National Research Foundation, 1 Old Faure road, Somerset West 7129, PO Box 722, Western Cape (South Africa); Nuru, Z.Y.; Kotsedi, L.; Bouziane, Kh. [UNESCO-UNISA Africa Chair in Nanosciences-Nanotechnology, College of Graduate Studies, University of South Africa, Muckleneuk ridge, PO Box 392, Pretoria (South Africa); Nanosciences African Network (NANOAFNET), iThemba LABS-National Research Foundation, 1 Old Faure road, Somerset West 7129, PO Box 722, Western Cape (South Africa); Mothudi, B.M. [UNESCO-UNISA Africa Chair in Nanosciences-Nanotechnology, College of Graduate Studies, University of South Africa, Muckleneuk ridge, PO Box 392, Pretoria (South Africa); Physics Dept., University of South Africa, Muckleneuk ridge, PO Box 392, Pretoria (South Africa); Maaza, M. [UNESCO-UNISA Africa Chair in Nanosciences-Nanotechnology, College of Graduate Studies, University of South Africa, Muckleneuk ridge, PO Box 392, Pretoria (South Africa); Nanosciences African Network (NANOAFNET), iThemba LABS-National Research Foundation, 1 Old Faure road, Somerset West 7129, PO Box 722, Western Cape (South Africa)

    2015-08-30

    Highlights: • Co-Al{sub 2}O{sub 3} was synthesized by electrodeposition & femtosecond laser structuring. • The ultrafast laser structuring significantly increases the solar absorption. • Co-Al{sub 2}O{sub 3} exhibited 0.98 solar absorptance and 0.03 thermal emittance. - Abstract: We report on the structural and optical properties of laser surface structured Co nanocylinders-Al{sub 2}O{sub 3} cermets on flexible Aluminium substrate for enhanced solar selective absorbers applications. This new family of solar selective absorbers coating consisting of Co nanocylinders embedded into nanoporous alumina template which were produced by standard electrodeposition and thereafter submitted to femtosecond laser surface structuring. While their structural and chemical properties were investigated by X-ray diffraction, scanning electron microscopy, energy dispersive spectrometry and atomic force microscopy, their optical characteristics were investigated by specular & diffuse reflectance. The optimized samples exhibit an elevated optical absorptance α(λ) above 98% and an emittance ε(λ) ∼0.03 in the spectral range of 200–1100 nm. This set of values was suggested to be related to several surface and volume phenomena such as light trapping, plasmon surface effect as well as angular dependence of light reflection induced by the ultrafast laser multi-scale structuring.

  10. Selective removal of esthetic composite restorations with spectral guided laser ablation

    Science.gov (United States)

    Yi, Ivana; Chan, Kenneth H.; Tsuji, Grant H.; Staninec, Michal; Darling, Cynthia L.; Fried, Daniel

    2016-02-01

    Dental composites are used for a wide range of applications such as fillings for cavities, adhesives for orthodontic brackets, and closure of gaps (diastemas) between teeth by esthetic bonding. Anterior restorations are used to replace missing, diseased and unsightly tooth structure for both appearance and function. When these restorations must be replaced, they are difficult to remove mechanically without causing excessive removal or damage to enamel because dental composites are color matched to teeth. Previous studies have shown that CO2 lasers have high ablation selectivity and are well suited for removal of composite on occlusal surfaces while minimizing healthy tissue loss. A spectral feedback guidance system may be used to discriminate between dental composite and dental hard tissue for selective ablation of composite material. The removal of composite restorations filling diastemas is more challenging due to the esthetic concern for anterior teeth. The objective of this study is to determine if composite spanning a diastema between anterior teeth can be removed by spectral guided laser ablation at clinically relevant rates with minimal damage to peripheral healthy tissue and with higher selectivity than a high speed dental handpiece.

  11. Optimization of spectrally selective Si/SiO2 based filters for thermophotovoltaic devices

    Science.gov (United States)

    Khosroshahi, Farhad Kazemi; Ertürk, Hakan; Pınar Mengüç, M.

    2017-08-01

    Design of a spectrally selective filter based on one-dimensional Si/SiO2 layers is considered for improved performance of thermo-photovoltaic devices. Spectrally selective filters transmit only the convertible radiation from the emitter as non-convertible radiation leads to a reduction in cell efficiency due to heating. The presented Si/SiO2 based filter concept reflects the major part of the undesired range back to the emitter to minimize energy required for the process and it is adaptable to different types of cells and emitters with different temperatures since its cut-off wavelength can be tuned. While this study mainly focuses on InGaSb based thermo-photovoltaic cell, Si, GaSb, and Ga0.78In0.22As0.19Sb0.81 based cells are also examined. Transmittance of the structure is predicted by rigorous coupled wave approach. Genetic algorithm, which is a global optimization method, is used to find the best possible filter structure by considering the overall efficiency as an objective function that is maximized. The simulations show that significant enhancement in the overall system and device efficiency is possible by using such filters with TPV devices. The methodology described in this paper allows for an improved filter design procedure for selected applications.

  12. Spectrally selective imaging with wideband balanced steady-state free precession MRI.

    Science.gov (United States)

    Çukur, Tolga

    2016-03-01

    Unwanted, bright fat signals in balanced steady-state free precession sequences are commonly suppressed using spectral shaping. Here, a new spectral-shaping method is proposed to significantly improve the uniformity of stopband suppression without compromising the level of passband signals. The proposed method combines binomial-pattern excitation pulses with a wideband balanced steady-state free precession sequence kernel. It thereby increases the frequency separation between the centers of pass and stopbands by π radians, enabling improved water-fat contrast. Simulations were performed to find the optimal flip angles and subpulse spacing for the binomial pulses that maximize contrast and signal efficiency. Comparisons with a conventional binomial balanced steady-state free precession sequence were performed in simulations as well as phantom and in vivo experiments at 1.5 T and 3 T. Enhanced fat suppression is demonstrated in vivo with an average improvement of 58% in blood-fat and 68% in muscle-fat contrast (P steady-state free precession method is a promising candidate for spectrally selective imaging with enhanced reliability against field inhomogeneities. © 2015 Wiley Periodicals, Inc.

  13. High Spectral Resolution, High Cadence, Imaging X-ray Microcalorimeters for Solar Physics - Phase 2 Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Microcalorimeter x-ray instruments are non-dispersive, high spectral resolution, broad-band, high cadence imaging spectrometers. We have been developing these...

  14. The SATIRE-S model and why getting solar cycle spectral irradiance trends correct is so important

    Science.gov (United States)

    Ball, William; Haigh, Joanna; Krivova, Natalie; Unruh, Yvonne; Solanki, Sami

    2014-05-01

    There is currently a wide range of potential spectral solar irradiance (SSI) solar cycle (SC) amplitudes suggested by observations and models. Therefore, SSI SC changes are still not fully understood. The magnitude of the SC flux changes has a direct impact upon the temperature and chemistry of the Earth's atmosphere. To contribute to an understanding of the solar-climate connection, it is critical that we, as the solar community, communicate effectively with the climate community, providing uncertainties in SSI data and assessments of possible SSI options. We present the SATIRE-S reconstruction in the context of these SSI datasets. SATIRE-S is a physically based, consistent SSI reconstruction over the last three solar cycles. It shows different SC spectral variability at all wavelengths compared to the NRLSSI model, widely used in climate research. Most-importantly, SC changes in the ultra-violet (UV) can be twice as large in SATIRE-S as NRLSSI. Typically NRLSSI provides a lower limit of SC SSI UV variability. SORCE satellite observations provide SC magnitudes at the upper limit of variability, exceeding that of SATIRE-S by a factor of three at some UV wavelengths. There is currently no way to be certain if any of these three SSI datasets, or others, is correct. We also present the SSI datasets in terms of their impact on stratospheric ozone, within a 2D atmospheric model, as an example of why it is important to get SC changes correct. Using NRLSSI results in the 2D atmospheric model, we see a decrease in ozone concentration at all altitudes from solar maximum to minimum. SATIRE-S and SORCE/SOLSTICE observations instead show an increase in ozone concentration in the mesosphere. The magnitude of the increase in the mesosphere when using SOLSTICE also depends greatly upon the version of the data, which means that studies using different data versions of SOLSTICE may lead to different conclusions. These results highlight why an accurate understanding of SC SSI

  15. THE HUBBLE WIDE FIELD CAMERA 3 TEST OF SURFACES IN THE OUTER SOLAR SYSTEM: SPECTRAL VARIATION ON KUIPER BELT OBJECTS

    International Nuclear Information System (INIS)

    Fraser, Wesley C.; Brown, Michael E.; Glass, Florian

    2015-01-01

    Here, we present additional photometry of targets observed as part of the Hubble Wide Field Camera 3 (WFC3) Test of Surfaces in the Outer Solar System. Twelve targets were re-observed with the WFC3 in the optical and NIR wavebands designed to complement those used during the first visit. Additionally, all of the observations originally presented by Fraser and Brown were reanalyzed through the same updated photometry pipeline. A re-analysis of the optical and NIR color distribution reveals a bifurcated optical color distribution and only two identifiable spectral classes, each of which occupies a broad range of colors and has correlated optical and NIR colors, in agreement with our previous findings. We report the detection of significant spectral variations on five targets which cannot be attributed to photometry errors, cosmic rays, point-spread function or sensitivity variations, or other image artifacts capable of explaining the magnitude of the variation. The spectrally variable objects are found to have a broad range of dynamical classes and absolute magnitudes, exhibit a broad range of apparent magnitude variations, and are found in both compositional classes. The spectrally variable objects with sufficiently accurate colors for spectral classification maintain their membership, belonging to the same class at both epochs. 2005 TV189 exhibits a sufficiently broad difference in color at the two epochs that span the full range of colors of the neutral class. This strongly argues that the neutral class is one single class with a broad range of colors, rather than the combination of multiple overlapping classes

  16. Designing a dual-mode broadband solar spectral converter: The example of Bi{sup 3+}, Cr{sup 3+}, Yb{sup 3+}-tridoped perovskite

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Li-Tian; Wu, Xuan-Ming; Wang, Ting; Chen, Dong-Ju; Deng, Chao; Meng, Jian-Xin, E-mail: tmjx@jnu.edu.cn; Cao, Li-Wei

    2016-07-15

    A promising dual-mode broadband solar spectral converter CaTiO{sub 3}: Bi{sup 3+}, Cr{sup 3+}, Yb{sup 3+} was successfully developed by solid-stated reaction. The structure, photoluminescence (PL), photoluminescence excitation (PLE) and diffuse reflectance (DR) spectra in the UV–vis–NIR region have been systematically investigated. The results show that the as-prepared samples simultaneously exhibit two distinct spectral converting patterns, nonlinear quantum-cutting (QC) involving Bi{sup 3+}–Ti{sup 4+} metal-to-metal charge transfer state (BT-MMCTs) → Yb{sup 3+}: {sup 2}F{sub 5/2} + Yb{sup 3+}: {sup 2}F{sub 5/2} and linear downshift (DS) involving Cr{sup 3+}: {sup 4}T{sub 2} → Yb{sup 3+}: {sup 2}F{sub 5/2}. It deduces that the nonlinear QC is based on a cooperative energy transfer (CET) process while the linear DS belongs to a dipole–dipole mechanism. With the present converter, broadband UV–vis (300–700 nm) photons, which are not fully utilized by the existing c-Si solar cells, can be efficiently harvested and converted into ∼1000 nm NIR photons via the dual-mode mechanism. Moreover, not only the PLE spectrum of CaTiO{sub 3}: Bi{sup 3+}, Cr{sup 3+}, Yb{sup 3+} matched well with that of the solar radiation, but also its NIR emission peak position fell well over the spectral response of the commercial crystalline Si (c-Si) solar cells. This as-prepared dual-mode solar spectral converter with multiple advantages can simultaneously realize high quantum yield and broadband conversion, which offers a new and effective way to boost the conversion efficiency of c-Si solar cells. We believe this novel design of dual-mode solar spectral converters can inspire a direction for the synthesis of more advanced UV–vis–NIR phosphors that can be used in Si solar cells. - Highlights: • A dual-mode broadband solar spectral converter is designed and developed. • The energy transfer mechanism relies on quantum-cutting as well as downshift. • The PLE

  17. Selective Removal of Residual Orthodontic Composite Using a Rapidly Scanned Carbon Dioxide Laser with Spectral Feedback

    Science.gov (United States)

    Hirasuna, Krista

    Background and Objective: Excessive heat accumulation within the tooth, incomplete removal of composite, and variable damage to the enamel are shortcomings of using conventional burs to remove residual orthodontic composite after debonding fixed appliances. The objective of this study was to determine if composite could be selectively removed from the enamel surface using a rapidly scanned carbon dioxide laser controlled by spectral feedback. Materials and Methods: A carbon dioxide laser operating at a wavelength of 9.3 microm with a pulse duration of 10-15 micros and a pulse repetition rate of ˜ 200 Hz was used to selectively remove composite from the buccal surfaces of 21 extracted teeth. GrenGloo(TM) composite was used to better visualize residual composite and the amount of enamel lost was measured with optical microscopy. A spectral feedback system utilizing a miniature spectrometer was used to control the laser scanning system. Pulpal temperature measurements were performed during composite removal to determine if there was excessive heat accumulation. Results: The amount of enamel lost averaged 22.7microm +/- 8.9 and 25.3 microm +/- 9.4 for removal at 3.8 and 4.2 J/cm2, respectively. An average maximum temperature rise of 1.9°C +/- 1.5 was recorded, with no teeth approaching the critical value of 5.5°C. The average time of composite removal was 19.3 +/- 4.1 seconds. Conclusions: Residual orthodontic composite can be rapidly removed from the tooth surface using a rapidly scanned CO2 laser with spectral feedback, with minimal temperature rise within the pulp and with minimal damage to the underlying enamel surface.

  18. Identifying camellia oil adulteration with selected vegetable oils by characteristic near-infrared spectral regions

    Directory of Open Access Journals (Sweden)

    Xuan Chu

    2018-03-01

    Full Text Available In this paper, a methodology based on characteristic spectral bands of near infrared spectroscopy (1000–2500nm and multivariate analysis was proposed to identify camellia oil adulteration with vegetable oils. Sunflower, peanut and corn oils were selected to conduct the test. Pure camellia oil and that adulterated with varying concentrations (1–10% with the gradient of 1%, 10–40% with the gradient of 5%, 40–100% with the gradient of 10% of each type of the three vegetable oils were prepared, respectively. For each type of adulterated oil, full-spectrum partial least squares partial least squares (PLS models and synergy interval partial least squares (SI-PLS models were developed. Parameters of these models were optimized simultaneously by cross-validation. The SI-PLS models were proved to be better than the full-spectrum PLS models. In SI-PLS models, the correlation coefficients of predition set (Rp were 0.9992, 0.9998 and 0.9999 for adulteration with sunflower oil, peanut oil and corn oil seperately; the corresponding root mean square errors of prediction set (RMSEP were 1.23, 0.66 and 0.37. Furthermore, a new generic PLS model was built based on the characteristic spectral regions selected from the intervals of the three SI-PLS models to identify the oil adulterants, regardless of the adultrated oil types. The model achieved with Rp= 0.9988 and RMSEP = 1.52. These results indicated that the characteristic near infrared spectral regions could determine the level of adulteration in the camellia oil.

  19. Shuttle SBUV (SSBUV) Solar Spectral Irradiance V008 (SSBUVIRR) at GES DISC

    Data.gov (United States)

    National Aeronautics and Space Administration — The Shuttle Solar Backscatter Ultraviolet (SSBUV) level-2 irradiance data are available for eight space shuttle missions flown between 1989 and 1996. SSBUV, a...

  20. Review on the solar spectral variability in the EUV for space weather purposes

    Directory of Open Access Journals (Sweden)

    J. Lilensten

    2008-02-01

    Full Text Available The solar XUV-EUV flux is the main energy source in the terrestrial diurnal thermosphere: it produces ionization, dissociation, excitation and heating. Accurate knowledge of this flux is of prime importance for space weather. We first list the space weather applications that require nowcasting and forecasting of the solar XUV-EUV flux. We then review present models and discuss how they account for the variability of the solar spectrum. We show why the measurement of the full spectrum is difficult, and why it is illusory to retrieve it from its atmospheric effects. We then address the problem of determining a set of observations that are adapted for space weather purposes, in the frame of ionospheric studies. Finally, we review the existing and future space experiments that are devoted to the observation of the solar XUV-EUV spectrum.

  1. Design and fabrication of spectrally selective emitter for thermophotovoltaic system by using nano-imprint lithography

    Science.gov (United States)

    Kim, Jong-Moo; Park, Keum-Hwan; Kim, Da-Som; Hwang, Bo-yeon; Kim, Sun-Kyung; Chae, Hee-Man; Ju, Byeong-Kwon; Kim, Young-Seok

    2018-01-01

    Thermophotovoltaic (TPV) systems have attracted attention as promising power generation systems that can directly convert the radiant energy produced by the combustion of fuel into electrical energy. However, there is a fundamental limit of their conversion efficiency due to the broadband distribution of the radiant spectrum. To overcome this problem, several spectrally selective thermal emitter technologies have been investigated, including the fabrication of photonic crystal (PhC) structures. In this paper, we present some design rules based on finite-a difference time-domain (FDTD) simulation results for tungsten (W) PhC emitter. The W 2D PhC was fabricated by a simple nano-imprint lithography (NIL) process, and inductive coupled plasma reactive ion etching (ICP-RIE) with an isotropic etching process, the benefits and parameters of which are presented. The fabricated W PhC emitter showed spectrally selective emission near the infrared wavelength range, and the optical properties varied depending on the size of the nano-patterns. The measured results of the fabricated prototype structure correspond well to the simulated values. Finally, compared with the performance of a flat W emitter, the total thermal emitter efficiency was almost 3.25 times better with the 2D W PhC structure.

  2. Calculation of isotope selective excitation of uranium isotopes using spectral simulation method

    International Nuclear Information System (INIS)

    Al-Hassanieh, O.

    2009-06-01

    Isotope ratio enhancement factor and isotope selectivity of 235 U in five excitation schemes (I: 0→10069 cm - 1 →IP, II: 0 →10081 cm - 1 →IP, III: 0 →25349 cm - 1→ IP, IV: 0→28650 cm - 1 →IP, V: 0→16900 cm - 1 →34659 cm - 1 →IP), were computed by a spectral simulation approach. The effect of laser bandwidth and Doppler width on the isotope ratio enhancement factor and isotope selectivity of 235 U has been studied. The photoionization scheme V gives the highest isotope ratio enhancement factor. The main factors which effect the separation possibility are the isotope shift and the relative intensity of the transitions between hyperfine levels. The isotope ratio enhancement factor decreases exponentially by increasing the Doppler width and the laser bandwidth, where the effect of Doppler width is much greater than the effect of the laser bandwidth. (author)

  3. Non-Negative Spectral Learning and Sparse Regression-Based Dual-Graph Regularized Feature Selection.

    Science.gov (United States)

    Shang, Ronghua; Wang, Wenbing; Stolkin, Rustam; Jiao, Licheng

    2018-02-01

    Feature selection is an important approach for reducing the dimension of high-dimensional data. In recent years, many feature selection algorithms have been proposed, but most of them only exploit information from the data space. They often neglect useful information contained in the feature space, and do not make full use of the characteristics of the data. To overcome this problem, this paper proposes a new unsupervised feature selection algorithm, called non-negative spectral learning and sparse regression-based dual-graph regularized feature selection (NSSRD). NSSRD is based on the feature selection framework of joint embedding learning and sparse regression, but extends this framework by introducing the feature graph. By using low dimensional embedding learning in both data space and feature space, NSSRD simultaneously exploits the geometric information of both spaces. Second, the algorithm uses non-negative constraints to constrain the low-dimensional embedding matrix of both feature space and data space, ensuring that the elements in the matrix are non-negative. Third, NSSRD unifies the embedding matrix of the feature space and the sparse transformation matrix. To ensure the sparsity of the feature array, the sparse transformation matrix is constrained using the -norm. Thus feature selection can obtain accurate discriminative information from these matrices. Finally, NSSRD uses an iterative and alternative updating rule to optimize the objective function, enabling it to select the representative features more quickly and efficiently. This paper explains the objective function, the iterative updating rules and a proof of convergence. Experimental results show that NSSRD is significantly more effective than several other feature selection algorithms from the literature, on a variety of test data.

  4. Higher values of spectral response, absorption coefficient and external quantum efficiency of solar cell in the form of pyramids

    Science.gov (United States)

    Hamel, A.

    2017-05-01

    This paper presents a study on spectral response, absorption coefficient and external quantum efficiency of solar cell in the form of pyramid [1, 2]. We investigate to what extent and under what conditions we want to take advantage of ray incidence Seven times [3, 4]. It is found that these analyses can be used to determine the optimal surface texture which provides the best light trapping for solar cells in terms of the total internal reflection occurring in the high-index medium at incidence angles larger than the nominal critical angle [3-9]. One of the main contributions of this paper is the analysis and quantification of the influence of the opening between the heads of the two closest pyramids in textured surface for solar cells and its application on the photovoltaic parameters. In this model we show that the material can have seven successive incident ray absorptions instead of five currently, where we changed the direction of the reflected ray, by identifying and install the angle between the two neighbouring pyramids, the incidence angle, the opening between the heads of the two closest pyramids and their height. Thus, with an angle between the two neighbouring pyramid fixed at 12° and for angle of incidence fixed at 84°. For these values of the angle between the two neighbouring pyramids and incidence angle, the opening between the heads of the two closest pyramids fixed at 2.10 μm for a pyramid height of 10 μm. This leads to the largest possible increase in optical efficiency, such as spectral response, Absorption Coefficient and External Quantum Efficiency. The results are in good agreement with the available literature.

  5. Validation of the spectral mismatch correction factor using an LED-based solar simulator

    DEFF Research Database (Denmark)

    Riedel, Nicholas; Santamaria Lancia, Adrian Alejo; Thorsteinsson, Sune

    -halide light sources provide. In this work we will use an EcoSun10L LED module tester from Ecoprogetti to perform short circuit current (ISC) measurements under various class A, B and C spectra. We will apply a spectral mismatch correction to the measured ISC under each test spectrum per IEC 60904-7. In all...... scenarios, a small area mono-Si cell is used the reference cell and a similar mono-Si cell is used as the PV device under test (DUT). Finally, we quantify the variation of the DUT’s measured and spectrally corrected Isc under the class A, B and C test spectra....

  6. Can we use the ozone response in a CCM to say which solar spectral irradiance is most likely correct?

    Science.gov (United States)

    Ball, William; Rozanov, Eugene; Shapiro, Anna

    2015-04-01

    Ozone plays a key role in the temperature structure of the Earth's atmosphere and absorbs damaging ultraviolet (UV) solar radiation. Evidence suggests that variations in stratospheric ozone resulting from changes in solar UV output may have an important role to play in weather over the North Atlantic and Europe on decadal timescales through a "top-down" coupling with the troposphere. However, the magnitude of the stratospheric response to the Sun over the 11-year solar cycle (SC) depends primarily on how much the UV changes. SC UV changes differ significantly between different observational instruments and the observations and models. The substantial disagreements between existing SSI datasets lead to different atmospheric responses when they are used in climate models and, therefore, we still cannot fully understand and simulate the ozone variability. We use the SOCOL chemistry-climate model, in specified dynamics mode, to calculate the atmospheric response from using different spectral irradiance from the SATIRE-S and NRLSSI models and with SORCE observations and a constant Sun. We compare the ozone and hydroxl results from these runs with observations to try to determine which SSI dataset is most likely to be correct. This is important to get a better understanding of which SSI dataset should be used in climate modelling and what magnitude of UV variability the Sun has. This will lead to a better understanding of the Sun's influence upon our climate and weather.

  7. A New Spectral Shape-Based Record Selection Approach Using Np and Genetic Algorithms

    Directory of Open Access Journals (Sweden)

    Edén Bojórquez

    2013-01-01

    Full Text Available With the aim to improve code-based real records selection criteria, an approach inspired in a parameter proxy of spectral shape, named Np, is analyzed. The procedure is based on several objectives aimed to minimize the record-to-record variability of the ground motions selected for seismic structural assessment. In order to select the best ground motion set of records to be used as an input for nonlinear dynamic analysis, an optimization approach is applied using genetic algorithms focuse on finding the set of records more compatible with a target spectrum and target Np values. The results of the new Np-based approach suggest that the real accelerograms obtained with this procedure, reduce the scatter of the response spectra as compared with the traditional approach; furthermore, the mean spectrum of the set of records is very similar to the target seismic design spectrum in the range of interest periods, and at the same time, similar Np values are obtained for the selected records and the target spectrum.

  8. CONTINUUM INTENSITY AND [O i] SPECTRAL LINE PROFILES IN SOLAR 3D PHOTOSPHERIC MODELS: THE EFFECT OF MAGNETIC FIELDS

    Energy Technology Data Exchange (ETDEWEB)

    Fabbian, D.; Moreno-Insertis, F., E-mail: damian@iac.es, E-mail: fmi@iac.es [Instituto de Astrofísica de Canarias (IAC), E-38205 La Laguna, Tenerife (Spain)

    2015-04-01

    The importance of magnetic fields in three-dimensional (3D) magnetoconvection models of the Sun’s photosphere is investigated in terms of their influence on the continuum intensity at different viewing inclination angles and on the intensity profile of two [O i] spectral lines. We use the RH numerical radiative transfer code to perform a posteriori spectral synthesis on the same time series of magnetoconvection models used in our publications on the effect of magnetic fields on abundance determination. We obtain a good match of the synthetic disk-center continuum intensity to the absolute continuum values from the Fourier Transform Spectrometer (FTS) observational spectrum; the match of the center-to-limb variation synthetic data to observations is also good, thanks, in part, to the 3D radiation transfer capabilities of the RH code. The different levels of magnetic flux in the numerical time series do not modify the quality of the match. Concerning the targeted [O i] spectral lines, we find, instead, that magnetic fields lead to nonnegligible changes in the synthetic spectrum, with larger average magnetic flux causing both of the lines to become noticeably weaker. The photospheric oxygen abundance that one would derive if instead using nonmagnetic numerical models would thus be lower by a few to several centidex. The inclusion of magnetic fields is confirmed to be important for improving the current modeling of the Sun, here in particular in terms of spectral line formation and of deriving consistent chemical abundances. These results may shed further light on the still controversial issue regarding the precise value of the solar oxygen abundance.

  9. 3d Approach Of Spectral Response For A Bifacial Silicon Solar Cell ...

    African Journals Online (AJOL)

    Losses in emitter region and external magnetic field are also being taken into account in order to perfect the description of measured spectral response. Then the new analytical expressions of carrier, photocurrent and short circuit densities are produced for front side and rear side illuminations. Homemade software based ...

  10. Study on the effects of sample selection on spectral reflectance reconstruction based on the algorithm of compressive sensing

    International Nuclear Information System (INIS)

    Zhang, Leihong; Liang, Dong

    2016-01-01

    In order to solve the problem that reconstruction efficiency and precision is not high, in this paper different samples are selected to reconstruct spectral reflectance, and a new kind of spectral reflectance reconstruction method based on the algorithm of compressive sensing is provided. Four different color numbers of matte color cards such as the ColorChecker Color Rendition Chart and Color Checker SG, the copperplate paper spot color card of Panton, and the Munsell colors card are chosen as training samples, the spectral image is reconstructed respectively by the algorithm of compressive sensing and pseudo-inverse and Wiener, and the results are compared. These methods of spectral reconstruction are evaluated by root mean square error and color difference accuracy. The experiments show that the cumulative contribution rate and color difference of the Munsell colors card are better than those of the other three numbers of color cards in the same conditions of reconstruction, and the accuracy of the spectral reconstruction will be affected by the training sample of different numbers of color cards. The key technology of reconstruction means that the uniformity and representation of the training sample selection has important significance upon reconstruction. In this paper, the influence of the sample selection on the spectral image reconstruction is studied. The precision of the spectral reconstruction based on the algorithm of compressive sensing is higher than that of the traditional algorithm of spectral reconstruction. By the MATLAB simulation results, it can be seen that the spectral reconstruction precision and efficiency are affected by the different color numbers of the training sample. (paper)

  11. Measuring the iron spectral opacity in solar conditions using a double ablation front scheme

    Energy Technology Data Exchange (ETDEWEB)

    Colaitis, A. [Centre Lasers Intenses et Applications, Talence (France); CEA/DRF/IRFU/DAp, CEA Saclay (France); Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Univ. of Rochester, NY (United States). Lab. for Laser Energetics; Ducret, J. E. [Centre Lasers Intenses et Applications, Talence (France); CEA/DRF/IRFU/DAp, CEA Saclay (France); Turck-Chieze, S [CEA/DRF/IRFU/DAp, CEA Saclay (France); Pennec, M L [CEA/DRF/IRFU/DAp, CEA Saclay (France); CEA/DIF, Arpajon (France); Blancard, C [CEA/DIF, Arpajon (France)

    2018-01-22

    We propose a new method to achieve hydrodynamic conditions relevant for the investigation of the radiation transport properties of the plasma at the base of the solar convection zone. The method is designed in the framework of opacity measurements with high-power lasers and exploits the temporal and spatial stability of hydrodynamic parameters in counter-propagating Double Ablation Front (DAF) structures.

  12. Combined retrieval of Arctic liquid water cloud and surface snow properties using airborne spectral solar remote sensing

    Science.gov (United States)

    Ehrlich, André; Bierwirth, Eike; Istomina, Larysa; Wendisch, Manfred

    2017-09-01

    The passive solar remote sensing of cloud properties over highly reflecting ground is challenging, mostly due to the low contrast between the cloud reflectivity and that of the underlying surfaces (sea ice and snow). Uncertainties in the retrieved cloud optical thickness τ and cloud droplet effective radius reff, C may arise from uncertainties in the assumed spectral surface albedo, which is mainly determined by the generally unknown effective snow grain size reff, S. Therefore, in a first step the effects of the assumed snow grain size are systematically quantified for the conventional bispectral retrieval technique of τ and reff, C for liquid water clouds. In general, the impact of uncertainties of reff, S is largest for small snow grain sizes. While the uncertainties of retrieved τ are independent of the cloud optical thickness and solar zenith angle, the bias of retrieved reff, C increases for optically thin clouds and high Sun. The largest deviations between the retrieved and true original values are found with 83 % for τ and 62 % for reff, C. In the second part of the paper a retrieval method is presented that simultaneously derives all three parameters (τ, reff, C, reff, S) and therefore accounts for changes in the snow grain size. Ratios of spectral cloud reflectivity measurements at the three wavelengths λ1 = 1040 nm (sensitive to reff, S), λ2 = 1650 nm (sensitive to τ), and λ3 = 2100 nm (sensitive to reff, C) are combined in a trispectral retrieval algorithm. In a feasibility study, spectral cloud reflectivity measurements collected by the Spectral Modular Airborne Radiation measurement sysTem (SMART) during the research campaign Vertical Distribution of Ice in Arctic Mixed-Phase Clouds (VERDI, April/May 2012) were used to test the retrieval procedure. Two cases of observations above the Canadian Beaufort Sea, one with dense snow-covered sea ice and another with a distinct snow-covered sea ice edge are analysed. The retrieved values of τ, reff

  13. Combined retrieval of Arctic liquid water cloud and surface snow properties using airborne spectral solar remote sensing

    Directory of Open Access Journals (Sweden)

    A. Ehrlich

    2017-09-01

    Full Text Available The passive solar remote sensing of cloud properties over highly reflecting ground is challenging, mostly due to the low contrast between the cloud reflectivity and that of the underlying surfaces (sea ice and snow. Uncertainties in the retrieved cloud optical thickness τ and cloud droplet effective radius reff, C may arise from uncertainties in the assumed spectral surface albedo, which is mainly determined by the generally unknown effective snow grain size reff, S. Therefore, in a first step the effects of the assumed snow grain size are systematically quantified for the conventional bispectral retrieval technique of τ and reff, C for liquid water clouds. In general, the impact of uncertainties of reff, S is largest for small snow grain sizes. While the uncertainties of retrieved τ are independent of the cloud optical thickness and solar zenith angle, the bias of retrieved reff, C increases for optically thin clouds and high Sun. The largest deviations between the retrieved and true original values are found with 83 % for τ and 62 % for reff, C.In the second part of the paper a retrieval method is presented that simultaneously derives all three parameters (τ, reff, C, reff, S and therefore accounts for changes in the snow grain size. Ratios of spectral cloud reflectivity measurements at the three wavelengths λ1 = 1040 nm (sensitive to reff, S, λ2 = 1650 nm (sensitive to τ, and λ3 = 2100 nm (sensitive to reff, C are combined in a trispectral retrieval algorithm. In a feasibility study, spectral cloud reflectivity measurements collected by the Spectral Modular Airborne Radiation measurement sysTem (SMART during the research campaign Vertical Distribution of Ice in Arctic Mixed-Phase Clouds (VERDI, April/May 2012 were used to test the retrieval procedure. Two cases of observations above the Canadian Beaufort Sea, one with dense snow-covered sea ice and another with a distinct snow-covered sea ice

  14. Grid Size Selection for Nonlinear Least-Squares Optimization in Spectral Estimation and Array Processing

    DEFF Research Database (Denmark)

    Nielsen, Jesper Kjær; Jensen, Tobias Lindstrøm; Jensen, Jesper Rindom

    2016-01-01

    time. Additionally, we show via three common examples how the grid size depends on parameters such as the number of data points or the number of sensors in DOA estimation. We also demonstrate that the computation time can potentially be lowered by several orders of magnitude by combining a coarse grid......In many spectral estimation and array processing problems, the process of finding estimates of model parameters often involves the optimisation of a cost function containing multiple peaks and dips. Such non-convex problems are hard to solve using traditional optimisation algorithms developed...... for convex problems, and computationally intensive grid searches are therefore often used instead. In this paper, we establish an analytical connection between the grid size and the parametrisation of the cost function so that the grid size can be selected as coarsely as possible to lower the computation...

  15. Black silicon laser-doped selective emitter solar cell with 18.1% efficiency

    DEFF Research Database (Denmark)

    Davidsen, Rasmus Schmidt; Li, Hongzhao; To, Alexander

    2016-01-01

    We report fabrication of nanostructured, laser-doped selective emitter (LDSE) silicon solar cells with power conversion efficiency of 18.1% and a fill factor (FF) of 80.1%. The nanostructured solar cells were realized through a single step, mask-less, scalable reactive ion etch (RIE) texturing......-texturing as well as the LDSE process, we consider this specific combination a promising candidate for a cost-efficient process for future Si solar cells....

  16. Aluminium or copper substrate panel for selective absorption of solar energy

    Science.gov (United States)

    Roberts, M. L.; Sharpe, M. H.; Krupnick, A. C. (Inventor)

    1979-01-01

    A method for making panels which selectively absorb solar energy is disclosed. The panels are comprised of an aluminum substrate, a layer of zinc thereon, a layer of nickel over the zinc layer and an outer layer of solar energy absorbing nickel oxide or a copper substrate with a layer of nickel thereon and a layer of solar energy absorbing nickel oxide distal from the copper substrate.

  17. A COMPARISON STUDY OF DIFFERENT MARKER SELECTION METHODS FOR SPECTRAL-SPATIAL CLASSIFICATION OF HYPERSPECTRAL IMAGES

    Directory of Open Access Journals (Sweden)

    D. Akbari

    2015-12-01

    Full Text Available An effective approach based on the Minimum Spanning Forest (MSF, grown from automatically selected markers using Support Vector Machines (SVM, has been proposed for spectral-spatial classification of hyperspectral images by Tarabalka et al. This paper aims at improving this approach by using image segmentation to integrate the spatial information into marker selection process. In this study, the markers are extracted from the classification maps, obtained by both SVM and segmentation algorithms, and then are used to build the MSF. The segmentation algorithms are the watershed, expectation maximization (EM and hierarchical clustering. These algorithms are used in parallel and independently to segment the image. Moreover, the pixels of each class, with the largest population in the classification map, are kept for each region of the segmentation map. Lastly, the most reliable classified pixels are chosen from among the exiting pixels as markers. Two benchmark urban hyperspectral datasets are used for evaluation: Washington DC Mall and Berlin. The results of our experiments indicate that, compared to the original MSF approach, the marker selection using segmentation algorithms leads in more accurate classification maps.

  18. Selective solar absorber emittance measurement at elevated temperature

    Science.gov (United States)

    Giraud, Philémon; Braillon, Julien; Raccurt, Olivier

    2017-06-01

    Durability of solar components for CSP (Concentrated Solar Power Plant) technologies is a key point to lower cost and ensure their large deployment. These technologies concentrated the solar radiation by means of mirrors on a receiver tube where it is collected as thermal energy. The absorbers are submitted to strong environmental constraints and the degradation of their optical properties (emittance and solar absorbance) have a direct impact on performance. The characterization of a material in such condition is complicated and requires advanced apparatuses, and different measurement methods exist for the determination of the two quantities of relevance regarding an absorber, which are its emittance and its solar absorbance. The objective is to develop new optical equipment for measure the emittance of this solar absorber at elevated temperature. In this paper, we present an optical bench developed for emittance measurement on absorbers is conditions of use. Results will be shown, with a discussion of some factors of influence over this measurement and how to control them.

  19. Scalable, "Dip-and-Dry" Fabrication of a Wide-Angle Plasmonic Selective Absorber for High-Efficiency Solar-Thermal Energy Conversion.

    Science.gov (United States)

    Mandal, Jyotirmoy; Wang, Derek; Overvig, Adam C; Shi, Norman N; Paley, Daniel; Zangiabadi, Amirali; Cheng, Qian; Barmak, Katayun; Yu, Nanfang; Yang, Yuan

    2017-11-01

    A galvanic-displacement-reaction-based, room-temperature "dip-and-dry" technique is demonstrated for fabricating selectively solar-absorbing plasmonic-nanoparticle-coated foils (PNFs). The technique, which allows for facile tuning of the PNFs' spectral reflectance to suit different radiative and thermal environments, yields PNFs which exhibit excellent, wide-angle solar absorptance (0.96 at 15°, to 0.97 at 35°, to 0.79 at 80°), and low hemispherical thermal emittance (0.10) without the aid of antireflection coatings. The thermal emittance is on par with those of notable selective solar absorbers (SSAs) in the literature, while the wide-angle solar absorptance surpasses those of previously reported SSAs with comparable optical selectivities. In addition, the PNFs show promising mechanical and thermal stabilities at temperatures of up to 200 °C. Along with the performance of the PNFs, the simplicity, inexpensiveness, and environmental friendliness of the "dip-and-dry" technique makes it an appealing alternative to current methods for fabricating selective solar absorbers. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. Assessment of performances of sun zenith angle and altitude parameterisations of atmospheric radiative transfer for spectral surface downwelling solar irradiance

    Science.gov (United States)

    Wald, L.; Blanc, Ph.

    2010-09-01

    Satellite-derived assessments of surface downwelling solar irradiance are more and more used by engineering companies in solar energy. Performances are judged satisfactory for the time being. Nevertheless, requests for more accuracy are increasing, in particular in the spectral definition and in the decomposition of the global radiation into direct and diffuse radiations. One approach to reach this goal is to improve both the modelling of the radiative transfer and the quality of the inputs describing the optical state. Within their joint project Heliosat-4, DLR and MINES ParisTech have adopted this approach to create advanced databases of solar irradiance succeeding to the current ones HelioClim and SolEMi. Regarding the model, we have opted for libRadtran, a well-known model of proven quality. As many similar models, running libRadtran is very time-consuming when it comes to process millions or more pixels or grid cells. This is incompatible with real-time operational process. One may adopt the abacus approach, or look-up tables, to overcome the problem. The model is run for a limited number of cases, covering the whole range of values taken by the various inputs of the model. Abaci are such constructed. For each real case, the irradiance value is computed by interpolating within the abaci. In this way, real-time can be envisioned. Nevertheless, the computation of the abaci themselves requires large computing capabilities. In addition, searching the abaci to find the values to interpolate can be time-consuming as the abaci are very large: several millions of values in total. Moreover, it raises the extrapolation problem of parameter out-of-range during the utilisation of the abaci. Parameterisation, when possible, is a means to reduce the amount of computations to be made and subsequently, the computation effort to create the abaci, the size of the abaci, the extrapolation and the searching time. It describes in analytical manner and with a few parameters the

  1. Physics of Solar Prominences: I-Spectral Diagnostics and Non-LTE Modelling

    Czech Academy of Sciences Publication Activity Database

    Labrosse, N.; Heinzel, Petr; Vial, J. C.; Kucera, T.; Parenti, S.; Gunár, Stanislav; Schmieder, B.; Kilper, G.

    2010-01-01

    Roč. 151, č. 4 (2010), s. 243-332 ISSN 0038-6308 R&D Projects: GA ČR GA205/07/1100 Grant - others:ESA(XE) ESA-PECS project No. 98030 Institutional research plan: CEZ:AV0Z10030501 Keywords : solar prominences * spectroscopy * radiative transfer Subject RIV: BB - Applied Statistics, Operational Research Impact factor: 4.433, year: 2010

  2. Radiation Dose Assessments of Solar Particle Events with Spectral Representation at High Energies for the Improvement of Radiation Protection

    Science.gov (United States)

    Kim, Myung-Hee; Atwell, William; Tylka, Allan J.; Dietrich, William F.; Cucinotta, Francis A.

    2010-01-01

    For radiation dose assessments of major solar particle events (SPEs), spectral functional forms of SPEs have been made by fitting available satellite measurements up to approx.100 MeV. However, very high-energy protons (above 500 MeV) have been observed with neutron monitors (NMs) in ground level enhancements (GLEs), which generally present the most severe radiation hazards to astronauts. Due to technical difficulties in converting NM data into absolutely normalized fluence measurements, those functional forms were made with little or no use of NM data. A new analysis of NM data has found that a double power law in rigidity (the so-called Band function) generally provides a satisfactory representation of the combined satellite and NM data from approx.10 MeV to approx.10 GeV in major SPEs (Tylka & Dietrich 2009). We use the Band function fits to re-assess human exposures from large SPEs. Using different spectral representations of large SPEs, variations of exposure levels were compared. The results can be applied to the development of approaches of improved radiation protection for astronauts, as well as the optimization of mission planning and shielding for future space missions.

  3. Albedos and spectral signatures determination and it connection to geological processes: Simile between Earth and other solar system bodies

    Science.gov (United States)

    Suarez, J.; Ochoa, L.; Saavedra, F.

    2017-07-01

    Remote sensing has always been the best investigation tool for planetary sciences. In this research have been used data of Surface albedo, electromagnetic spectra and satelital imagery in search of understanding glacier dynamics in some bodies of the solar system, and how it's related to their compositions and associated geological processes, this methodology is very common in icy moons studies. Through analytic software's some albedos map's and geomorphological analysis were made that allow interpretation of different types of ice in the glacier's and it's interaction with other materials, almost all the images were worked in the visible and infrared ranges of the spectrum; spectral data were later used to connect the reflectance whit chemical and reologic properties of the compounds studied. It have been concluded that the albedo analysis is an effective tool to differentiate materials in the bodies surfaces, but the application of spectral data is necessary to know the exact compounds of the glaciers and to have a better understanding of the icy bodies.

  4. Spectral model selection in the electronic measurement of the Boltzmann constant by Johnson noise thermometry

    Science.gov (United States)

    Coakley, Kevin J.; Qu, Jifeng

    2017-04-01

    In the electronic measurement of the Boltzmann constant based on Johnson noise thermometry, the ratio of the power spectral densities of thermal noise across a resistor at the triple point of water, and pseudo-random noise synthetically generated by a quantum-accurate voltage-noise source is constant to within 1 part in a billion for frequencies up to 1 GHz. Given knowledge of this ratio, and the values of other parameters that are known or measured, one can determine the Boltzmann constant. Due, in part, to mismatch between transmission lines, the experimental ratio spectrum varies with frequency. We model this spectrum as an even polynomial function of frequency where the constant term in the polynomial determines the Boltzmann constant. When determining this constant (offset) from experimental data, the assumed complexity of the ratio spectrum model and the maximum frequency analyzed (fitting bandwidth) dramatically affects results. Here, we select the complexity of the model by cross-validation—a data-driven statistical learning method. For each of many fitting bandwidths, we determine the component of uncertainty of the offset term that accounts for random and systematic effects associated with imperfect knowledge of model complexity. We select the fitting bandwidth that minimizes this uncertainty. In the most recent measurement of the Boltzmann constant, results were determined, in part, by application of an earlier version of the method described here. Here, we extend the earlier analysis by considering a broader range of fitting bandwidths and quantify an additional component of uncertainty that accounts for imperfect performance of our fitting bandwidth selection method. For idealized simulated data with additive noise similar to experimental data, our method correctly selects the true complexity of the ratio spectrum model for all cases considered. A new analysis of data from the recent experiment yields evidence for a temporal trend in the offset

  5. Effect of method and parameters of spectral analysis on selected indices of simulated Doppler spectra.

    Science.gov (United States)

    Kaluzynski, K; Palko, T

    1993-05-01

    The sensitivity of Doppler spectral indices (mean frequency, maximum frequency, spectral broadening index and turbulence intensity) to the conditions of spectral analysis (estimation method, data window, smoothing window or model order) increases with decreasing signal bandwidth and growing index complexity. The bias of spectral estimate has a more important effect on these indices than its variance. A too low order, in the case of autoregressive modeling and minimum variance methods, and excessive smoothing, in the case of the FFT method, result in increased errors of Doppler spectral indices. There is a trade-off between the errors resulting from a short data window and those due to insufficient temporal resolution.

  6. Efficiency enhancement calculations of state-of-the-art solar cells by luminescent layers with spectral shifting, quantum cutting, and quantum tripling function

    NARCIS (Netherlands)

    Ten Kate, O.M.; De Jong, M.; Hintzen, H.T.; Van der Kolk, E.

    2013-01-01

    Solar cells of which the efficiency is not limited by the Shockley-Queisser limit can be obtained by integrating a luminescent spectral conversion layer into the cell structure. We have calculated the maximum efficiency of state-of-the-art c-Si, pc-Si, a-Si, CdTe, GaAs, CIS, CIGS, CGS, GaSb, and Ge

  7. Observational study on the fine structure and dynamics of a solar jet. II. Energy release process revealed by spectral analysis

    Science.gov (United States)

    Sakaue, Takahito; Tei, Akiko; Asai, Ayumi; Ueno, Satoru; Ichimoto, Kiyoshi; Shibata, Kazunari

    2018-01-01

    We report on a solar jet phenomenon associated with the C5.4 class flare on 2014 November 11. The data of the jet was provided by the Solar Dynamics Observatory, the X-Ray Telescope (XRT) aboard Hinode, and the Interface Region Imaging Spectrograph and Domeless Solar Telescope (DST) at Hida Observatory, Kyoto University. These plentiful data enabled us to present this series of papers to discuss all the processes of the observed phenomena, including energy storage, event trigger, and energy release. In this paper, we focus on the energy release process of the observed jet, and mainly describe our spectral analysis on the Hα data of DST to investigate the internal structure of the Hα jet and its temporal evolution. This analysis reveals that in the physical quantity distributions of the Hα jet, such as line-of-sight velocity and optical thickness, there is a significant gradient in the direction crossing the jet. We interpret this internal structure as the consequence of the migration of the energy release site, based on the idea of ubiquitous reconnection. Moreover, by measuring the horizontal flow of the fine structures in the jet, we succeeded in deriving the three-dimensional velocity field and the line-of-sight acceleration field of the Hα jet. The analysis result indicates that part of the ejecta in the Hα jet experienced additional acceleration after it had been ejected from the lower atmosphere. This secondary acceleration was found to occur in the vicinity of the intersection between the trajectories of the Hα jet and the X-ray jet observed by Hinode/XRT. We propose that a fundamental cause of this phenomenon is magnetic reconnection involving the plasmoid in the observed jet.

  8. Gradient SiNO anti-reflective layers in solar selective coatings

    Science.gov (United States)

    Ren, Zhifeng; Cao, Feng; Sun, Tianyi; Chen, Gang

    2017-08-01

    A solar selective coating includes a substrate, a cermet layer having nanoparticles therein deposited on the substrate, and an anti-reflection layer deposited on the cermet layer. The cermet layer and the anti-reflection layer may each be formed of intermediate layers. A method for constructing a solar-selective coating is disclosed and includes preparing a substrate, depositing a cermet layer on the substrate, and depositing an anti-reflection layer on the cermet layer.

  9. Measures for diffusion of solar PV in selected African countries

    DEFF Research Database (Denmark)

    Nygaard, Ivan; Hansen, Ulrich Elmer; Mackenzie, Gordon A.

    2017-01-01

    that governments’ strategies to promoting solar PV are moving from isolated projects towards frameworks for market development and that there are high expectations to upgrading in the PV value chain through local assembly of panels and local production of other system elements. Commonly identified measures include......This paper investigates how African governments are considering supporting and promoting the diffusion of solar PV. This issue is explored by examining so-called ‘technology action plans (TAPs)’, which were main outputs of the Technology Needs Assessment project implemented in 10 African countries...... from 2010 to 2013. The paper provides a review of three distinct but characteristic trajectories for PV market development in Kenya (private-led market for solar home systems), Morocco (utility-led fee-for service model) and Rwanda (donorled market for institutional systems). The paper finds...

  10. A Novel Extension Decision-Making Method for Selecting Solar Power Systems

    Directory of Open Access Journals (Sweden)

    Meng-Hui Wang

    2013-01-01

    Full Text Available Due to the complex parameters of a solar power system, the designer not only must think about the load demand but also needs to consider the price, weight, and annual power generating capacity (APGC and maximum power of the solar system. It is an important task to find the optimal solar power system with many parameters. Therefore, this paper presents a novel decision-making method based on the extension theory; we call it extension decision-making method (EDMM. Using the EDMM can make it quick to select the optimal solar power system. The paper proposed this method not only to provide a useful estimated tool for the solar system engineers but also to supply the important reference with the installation of solar systems to the consumer.

  11. POWER SPECTRAL DENSITY OF FLUCTUATIONS OF BULK AND THERMAL SPEEDS IN THE SOLAR WIND

    International Nuclear Information System (INIS)

    Šafránková, J.; Němeček, Z.; Němec, F.; Přech, L.; Chen, C. H. K.; Zastenker, G. N.

    2016-01-01

    This paper analyzes solar wind power spectra of bulk and thermal speed fluctuations that are computed with a time resolution of 32 ms in the frequency range of 0.001–2 Hz. The analysis uses measurements of the Bright Monitor of the Solar Wind on board the Spektr-R spacecraft that are limited to 570 km s 1 bulk speed. The statistics, based on more than 42,000 individual spectra, show that: (1) the spectra of bulk and thermal speeds can be fitted by two power-law segments; (2) despite their large variations, the parameters characterizing frequency spectrum fits computed on each particular time interval are very similar for both quantities; (3) the median slopes of the bulk and thermal speeds of the segment attributed to the MHD scale are 1.43 and 1.38, respectively, whereas they are 3.08 and 2.43 in the kinetic range; (4) the kinetic range slopes of bulk and thermal speed spectra become equal when either the ion density or magnetic field strength are high; (5) the break between MHD and kinetic scales seems to be controlled by the ion β parameter; (6) the best scaling parameter for bulk and thermal speed variations is a sum of the inertial length and proton thermal gyroradius; and (7) the above conclusions can be applied to the density variations if the background magnetic field is very low.

  12. Variation of solar-selective properties of black chrome with plating time

    Science.gov (United States)

    Mcdonald, G. E.; Curtis, H. B.

    1975-01-01

    The spectral reflectance properties of a commercially prepared black chrome over dull nickel, both plated on steel, for various plating times of the black chrome were measured. The plating current was 180 amperes per square foot. Values of absorptance integrated over the solar spectrum, and of infrared emittance integrated over black-body radiation at 250 F were obtained. It is shown that plating between one and two minutes produces the optimum combination of highest heat absorbed and lowest heat lost by radiation.

  13. Physics of Solar Prominences: I-Spectral Diagnostics and Non-LTE Modelling

    Science.gov (United States)

    Labrosse, N.; Heinzel, P.; Vial, J.-C,; Kucera, T.; Parenti, S.; Gunar, S.; Schmieder, B.; Kilper, G.

    2010-01-01

    This review paper outlines background information and covers recent advances made via the analysis of spectra and images of prominence plasma and the increased sophistication of non-LTE (i.e. when there is a departure from Local Thermodynamic Equilibrium) radiative transfer models. We first describe the spectral inversion techniques that have been used to infer the plasma parameters important for the general properties of the prominence plasma in both its cool core and the hotter prominence-corona transition region. We also review studies devoted to the observation of bulk motions of the prominence plasma and to the determination of prominence mass. However, a simple inversion of spectroscopic data usually fails when the lines become optically thick at certain wavelengths. Therefore, complex

  14. Phase change material selection for small scale solar energy ...

    African Journals Online (AJOL)

    This paper focuses on choosing an appropriate phase change material for latent heat storing systems that can store excess energy of a small scale solar thermal power plant suitable for distributed or off grid power supply. Most commercially available thermal storage materials cater for Mega Watt scale power plants ...

  15. Selecting Solar. Insights into Residential Photovoltaic (PV) Quote Variation

    Energy Technology Data Exchange (ETDEWEB)

    Davidson, Carolyn [National Renewable Energy Lab. (NREL), Golden, CO (United States); Margolis, Robert [National Renewable Energy Lab. (NREL), Golden, CO (United States)

    2015-10-01

    This analysis leverages available data from EnergySage, an online solar marketplace, to offer the first data-driven characterization of quote variation faced by prospective PV customers, lending early insight into the decisions customers face once they have initial buy-in.

  16. Selected issues connected with determination of requirements of spectral properties of camouflage patterns

    Science.gov (United States)

    Racek, František; Jobánek, Adam; Baláž, Teodor; Krejčí, Jaroslav

    2017-10-01

    Traditionally spectral reflectance of the material is measured and compared with permitted spectral reflectance boundaries. The boundaries are limited by upper and lower curve of spectral reflectance. The boundaries for unique color has to fulfil the operational requirements as a versatility of utilization through the all year seasons, day and weather condition on one hand and chromatic and spectral matching with background as well as the manufacturability on the other hand. The interval between the boundaries suffers with ambivalent feature. Camouflage pattern producer would be happy to see it much wider, but blending effect into its particular background could be better with narrower tolerance limits. From the point of view of long time user of camouflage pattern battledress, there seems to be another ambivalent feature. Width of the tolerance zone reflecting natural dispersion of spectral reflectance values allows the significant distortions of shape of the spectral curve inside the given boundaries.

  17. UARS Solar-Stellar Irradiance Comparison Experiment (SOLSTICE) Level 3BS V001

    Data.gov (United States)

    National Aeronautics and Space Administration — The Solar-Stellar Irradiance Comparison Experiment (SOLSTICE) Level 3BS data product consists of daily, 1 nm resolution, solar spectral irradiances and selected...

  18. Solar selective coatings based on nickel oxide obtained via spray pyrolysis.

    Science.gov (United States)

    Voinea, Mihaela; Ienei, Elena; Bogatu, Cristina; Duta, Anca

    2009-07-01

    The paper presents the optimization process for obtaining NiO thin layers on copper substrate for solar absorber coatings, using an inexpensive and up-scalable technique: spray pyrolysis deposition (SPD). Efficient selective coatings must present a high absorption coefficient of the incident solar irradiation, and low emission of heat. The solar selective coatings design involves tailoring the surface properties for superior optical properties. The deposition parameters were varied for maximizing the solar absorbance and minimizing the thermal emittance. The film morphology was controlled using copolymers of the maleic anhydride as additives into the precursors' solution. The structural and surface properties of the films were investigated by X-ray diffraction and atomic force microscopy, respectively. The Cu/CuO(x)/NiO solar absorber shows good values for the solar absorptance (alpha(s) = 0.95) and thermal emittance (epsilon(T) = 0.05) compared with the ones obtained by other methods employed in literature and new additives are recommended in tailoring the surface of solar selective coatings.

  19. Hyper-spectral frequency selection for the classification of vegetation diseases

    NARCIS (Netherlands)

    Dijkstra, Klaas; van de Loosdrecht, Jaap; Schomaker, Lambert; Wiering, Marco

    2017-01-01

    Reducing the use of pesticides by early visual detection of diseases in precision agriculture is important. Because of the color similarity between potato-plant diseases, narrow band hyper-spectral imaging is required. Payload constraints on unmanned aerial vehicles require reduction of spectral

  20. Middle atmosphere response to different descriptions of the 11-yr solar cycle in spectral irradiance in a chemistry-climate model

    Directory of Open Access Journals (Sweden)

    W. H. Swartz

    2012-07-01

    Full Text Available The 11-yr solar cycle in solar spectral irradiance (SSI inferred from measurements by the SOlar Radiation & Climate Experiment (SORCE suggests a much larger variation in the ultraviolet than previously accepted. We present middle atmosphere ozone and temperature responses to the solar cycles in SORCE SSI and the ubiquitous Naval Research Laboratory (NRL SSI reconstruction using the Goddard Earth Observing System chemistry-climate model (GEOSCCM. The results are largely consistent with other recent modeling studies. The modeled ozone response is positive throughout the stratosphere and lower mesosphere using the NRL SSI, while the SORCE SSI produces a response that is larger in the lower stratosphere but out of phase with respect to total solar irradiance above 45 km. The modeled responses in total ozone are similar to those derived from satellite and ground-based measurements, 3–6 Dobson Units per 100 units of 10.7-cm radio flux (F10.7 in the tropics. The peak zonal mean tropical temperature response using the SORCE SSI is nearly 2 K per 100 units F10.7 – 3 times larger than the simulation using the NRL SSI. The GEOSCCM and the Goddard Space Flight Center (GSFC 2-D coupled model are used to examine how the SSI solar cycle affects the atmosphere through direct solar heating and photolysis processes individually. Middle atmosphere ozone is affected almost entirely through photolysis, whereas the solar cycle in temperature is caused both through direct heating and photolysis feedbacks, processes that are mostly linearly separable. This is important in that it means that chemistry-transport models should simulate the solar cycle in ozone well, while general circulation models without coupled chemistry will underestimate the temperature response to the solar cycle significantly in the middle atmosphere. Further, the net ozone response results from the balance of ozone production at wavelengths less than 242 nm

  1. NOMINAL VALUES FOR SELECTED SOLAR AND PLANETARY QUANTITIES: IAU 2015 RESOLUTION B3

    Energy Technology Data Exchange (ETDEWEB)

    Prša, Andrej [Villanova University, Department of Astrophysics and Planetary Science, 800 Lancaster Ave., Villanova, PA 19085 (United States); Harmanec, Petr [Astronomical Institute of the Charles University, Faculty of Mathematics and Physics, V Holešovičkách 2, CZ-180 00 Praha 8 (Czech Republic); Torres, Guillermo [Harvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138 (United States); Mamajek, Eric [Department of Physics and Astronomy, University of Rochester, Rochester, NY 14627-0171 (United States); Asplund, Martin [Research School of Astronomy and Astrophysics, Australian National University, Canberra, ACT 2611 (Australia); Capitaine, Nicole [SYRTE, Observatoire de Paris, PSL Research University, CNRS, Sorbonne Universités, UPMC, LNE, 61 avenue de lObservatoire, F-75014 Paris (France); Christensen-Dalsgaard, Jørgen [Stellar Astrophysics Centre, Department of Physics and Astronomy, Aarhus University, Ny Munkegade 120, DK-8000 Aarhus C (Denmark); Depagne, Éric [South African Astronomical Observatory, P.O. Box 9 Observatory, Cape Town (South Africa); Haberreiter, Margit [Physikalisch-Meteorologisches Observatorium Davos/World Radiation Center, Dorfstrasse 33, Davos (Switzerland); Hekker, Saskia [Max-Planck-Institut für Sonnensystemforschung, Justus-von-Liebig-Weg 3, D-37077 Göttingen (Germany); Hilton, James [US Naval Observatory, 3450 Massachusetts Ave. NW, Washington, DC 20392-5420 (United States); Kopp, Greg [Laboratory for Atmospheric and Space Physics, 1234 Innovation Drive, Boulder, CO 80303-7814 (United States); and others

    2016-08-01

    In this brief communication we provide the rationale for and the outcome of the International Astronomical Union (IAU) resolution vote at the XXIXth General Assembly in Honolulu, Hawaii, in 2015, on recommended nominal conversion constants for selected solar and planetary properties. The problem addressed by the resolution is a lack of established conversion constants between solar and planetary values and SI units: a missing standard has caused a proliferation of solar values (e.g., solar radius, solar irradiance, solar luminosity, solar effective temperature, and solar mass parameter) in the literature, with cited solar values typically based on best estimates at the time of paper writing. As precision of observations increases, a set of consistent values becomes increasingly important. To address this, an IAU Working Group on Nominal Units for Stellar and Planetary Astronomy formed in 2011, uniting experts from the solar, stellar, planetary, exoplanetary, and fundamental astronomy, as well as from general standards fields to converge on optimal values for nominal conversion constants. The effort resulted in the IAU 2015 Resolution B3, passed at the IAU General Assembly by a large majority. The resolution recommends the use of nominal solar and planetary values, which are by definition exact and are expressed in SI units. These nominal values should be understood as conversion factors only, not as the true solar/planetary properties or current best estimates. Authors and journal editors are urged to join in using the standard values set forth by this resolution in future work and publications to help minimize further confusion.

  2. NOMINAL VALUES FOR SELECTED SOLAR AND PLANETARY QUANTITIES: IAU 2015 RESOLUTION B3

    International Nuclear Information System (INIS)

    Prša, Andrej; Harmanec, Petr; Torres, Guillermo; Mamajek, Eric; Asplund, Martin; Capitaine, Nicole; Christensen-Dalsgaard, Jørgen; Depagne, Éric; Haberreiter, Margit; Hekker, Saskia; Hilton, James; Kopp, Greg

    2016-01-01

    In this brief communication we provide the rationale for and the outcome of the International Astronomical Union (IAU) resolution vote at the XXIXth General Assembly in Honolulu, Hawaii, in 2015, on recommended nominal conversion constants for selected solar and planetary properties. The problem addressed by the resolution is a lack of established conversion constants between solar and planetary values and SI units: a missing standard has caused a proliferation of solar values (e.g., solar radius, solar irradiance, solar luminosity, solar effective temperature, and solar mass parameter) in the literature, with cited solar values typically based on best estimates at the time of paper writing. As precision of observations increases, a set of consistent values becomes increasingly important. To address this, an IAU Working Group on Nominal Units for Stellar and Planetary Astronomy formed in 2011, uniting experts from the solar, stellar, planetary, exoplanetary, and fundamental astronomy, as well as from general standards fields to converge on optimal values for nominal conversion constants. The effort resulted in the IAU 2015 Resolution B3, passed at the IAU General Assembly by a large majority. The resolution recommends the use of nominal solar and planetary values, which are by definition exact and are expressed in SI units. These nominal values should be understood as conversion factors only, not as the true solar/planetary properties or current best estimates. Authors and journal editors are urged to join in using the standard values set forth by this resolution in future work and publications to help minimize further confusion.

  3. Fourier-transform-infrared-spectroscopy based spectral-biomarker selection towards optimum diagnostic differentiation of oral leukoplakia and cancer.

    Science.gov (United States)

    Banerjee, Satarupa; Pal, Mousumi; Chakrabarty, Jitamanyu; Petibois, Cyril; Paul, Ranjan Rashmi; Giri, Amita; Chatterjee, Jyotirmoy

    2015-10-01

    In search of specific label-free biomarkers for differentiation of two oral lesions, namely oral leukoplakia (OLK) and oral squamous-cell carcinoma (OSCC), Fourier-transform infrared (FTIR) spectroscopy was performed on paraffin-embedded tissue sections from 47 human subjects (eight normal (NOM), 16 OLK, and 23 OSCC). Difference between mean spectra (DBMS), Mann-Whitney's U test, and forward feature selection (FFS) techniques were used for optimising spectral-marker selection. Classification of diseases was performed with linear and quadratic support vector machine (SVM) at 10-fold cross-validation, using different combinations of spectral features. It was observed that six features obtained through FFS enabled differentiation of NOM and OSCC tissue (1782, 1713, 1665, 1545, 1409, and 1161 cm(-1)) and were most significant, able to classify OLK and OSCC with 81.3 % sensitivity, 95.7 % specificity, and 89.7 % overall accuracy. The 43 spectral markers extracted through Mann-Whitney's U Test were the least significant when quadratic SVM was used. Considering the high sensitivity and specificity of the FFS technique, extracting only six spectral biomarkers was thus most useful for diagnosis of OLK and OSCC, and to overcome inter and intra-observer variability experienced in diagnostic best-practice histopathological procedure. By considering the biochemical assignment of these six spectral signatures, this work also revealed altered glycogen and keratin content in histological sections which could able to discriminate OLK and OSCC. The method was validated through spectral selection by the DBMS technique. Thus this method has potential for diagnostic cost minimisation for oral lesions by label-free biomarker identification.

  4. Spectral-splitting concentrator photovoltaic modules based on AlGaAs/GaAs/GaSb and GaInP/InGaAs(P) solar cells

    Science.gov (United States)

    Vlasov, A. S.; Khvostikov, V. P.; Karlina, L. B.; Sorokina, S. V.; Potapovich, N. S.; Shvarts, M. Z.; Timoshina, N. Kh.; Lantratov, V. M.; Mintairov, S. A.; Kalyuzhnyi, N. A.; Marukhina, E. P.; Andreev, V. M.

    2013-07-01

    A concentrator photovoltaic module with sunlight spectral splitting by Fresnel lens and dichroic filters is developed. The photoelectric conversion efficiency of such a module is estimated at a level of 49.4% when three single-junction cells are used and may reach 48.5-50.6% when a tandem two-junction cell is combined with narrow-band cells. Single-junction AlGaAs, GaAs, GaSb, and InGa(P)As solar sells are fabricated by zinc diffusion from the vapor phase into an n-type epitaxial layer. GaInP/GaAs cascade solar cells are prepared by MOS hydride epitaxy. The overall efficiency of the three single-junction solar cells developed for the spectral-splitting module is 38.1% (AM1.5D) at concentration ratio K c = 200x. The combination of the solar cells with the cascade structure demonstrates an efficiency of 37.9% at concentrations of 400-800 suns. The parameters of the spectral-splitting photovoltaic module are measured. The photovoltaic efficiency of this module reaches 24.7% in the case of three single-junction cells and 27.9% when the two-junction and single-junction cells are combined.

  5. Exposure to Non-Extreme Solar UV Daylight: Spectral Characterization, Effects on Skin and Photoprotection

    Directory of Open Access Journals (Sweden)

    Claire Marionnet

    2014-12-01

    Full Text Available The link between chronic sun exposure of human skin and harmful clinical consequences such as photo-aging and skin cancers is now indisputable. These effects are mostly due to ultraviolet (UV rays (UVA, 320–400 nm and UVB, 280–320 nm. The UVA/UVB ratio can vary with latitude, season, hour, meteorology and ozone layer, leading to different exposure conditions. Zenithal sun exposure (for example on a beach around noon under a clear sky can rapidly induce visible and well-characterized clinical consequences such as sunburn, predominantly induced by UVB. However, a limited part of the global population is exposed daily to such intense irradiance and until recently little attention has been paid to solar exposure that does not induce any short term clinical impact. This paper will review different studies on non-extreme daily UV exposures with: (1 the characterization and the definition of the standard UV daylight and its simulation in the laboratory; (2 description of the biological and clinical effects of such UV exposure in an in vitro reconstructed human skin model and in human skin in vivo, emphasizing the contribution of UVA rays and (3 analysis of photoprotection approaches dedicated to prevent the harmful impact of such UV exposure.

  6. Exposure to non-extreme solar UV daylight: spectral characterization, effects on skin and photoprotection.

    Science.gov (United States)

    Marionnet, Claire; Tricaud, Caroline; Bernerd, Françoise

    2014-12-23

    The link between chronic sun exposure of human skin and harmful clinical consequences such as photo-aging and skin cancers is now indisputable. These effects are mostly due to ultraviolet (UV) rays (UVA, 320-400 nm and UVB, 280-320 nm). The UVA/UVB ratio can vary with latitude, season, hour, meteorology and ozone layer, leading to different exposure conditions. Zenithal sun exposure (for example on a beach around noon under a clear sky) can rapidly induce visible and well-characterized clinical consequences such as sunburn, predominantly induced by UVB. However, a limited part of the global population is exposed daily to such intense irradiance and until recently little attention has been paid to solar exposure that does not induce any short term clinical impact. This paper will review different studies on non-extreme daily UV exposures with: (1) the characterization and the definition of the standard UV daylight and its simulation in the laboratory; (2) description of the biological and clinical effects of such UV exposure in an in vitro reconstructed human skin model and in human skin in vivo, emphasizing the contribution of UVA rays and (3) analysis of photoprotection approaches dedicated to prevent the harmful impact of such UV exposure.

  7. Preparation and characterization of CuO nanostructures on copper substrate as selective solar absorbers

    International Nuclear Information System (INIS)

    Karthick Kumar, S.; Murugesan, S.; Suresh, S.

    2014-01-01

    Selective solar absorber coatings of copper oxide (CuO) on copper substrates are prepared by room temperature oxidation of copper at different alkaline conditions. The surface morphology and structural analyses of the CuO coatings are carried out by scanning electron microscopy (SEM), X-ray diffraction (XRD), energy dispersive spectroscopy (EDS) and Raman spectroscopy techniques. XRD and Raman studies indicated the single phase nature and high crystallinity of the prepared CuO nanostructures. Different CuO nanostructures, viz., nanoneedles, nanofibers and nanoparticles are formed at different alkaline conditions. The influence of reaction time on morphology of the CuO nanostructures is also studied. The thermal emittance values of these nanostructured CuO samples are found to be in the range of 6–7% and their solar absorptances are ranged between 84 and 90%. The observed high solar selectivity values (>12.7) suggest that these coatings can be used as selective absorbers in solar thermal gadgets. - Highlights: • Nanostructured CuO thin films on Cu substrate have been prepared by a facile method. • Morphology of the CuO nanostructures varies with reaction pH. • The thin films show high absorptance in the visible region and low thermal emittance. • Multiple absorption in the porous structure leads to high solar absorptance. • Nanostructures posses solar selectivity values >12

  8. Quantification of Soil Properties with Hyperspectral Data: Selecting Spectral Variables with Different Methods to Improve Accuracies and Analyze Prediction Mechanisms

    Directory of Open Access Journals (Sweden)

    Michael Vohland

    2017-10-01

    Full Text Available We explored the potentials of both non-imaging laboratory and airborne imaging spectroscopy to assess arable soil quality indicators. We focused on microbial biomass-C (MBC and hot water-extractable C (HWEC, complemented by organic carbon (OC and nitrogen (N as well-studied spectrally active parameters. The aggregation of different spectral variable selection strategies was used to analyze benefits for reachable estimation accuracies and to explore spectral predictive mechanisms for MBC and HWEC. With selected variables, quantification accuracies improved markedly for MBC (laboratory: RPD = 2.32 instead of 1.33 with full spectra; airborne: 2.35 instead of 1.80 and OC (laboratory: RPD = 3.08 instead of 2.36; airborne: 2.20 instead of 1.94. Patterns of selected variables indicated similarities between HWEC and OC, but significant differences between all other soil variables. This agreed to our results of indirect approaches in which both (i wet-chemical data of OC and N and (ii spectra fitted to measured OC and N values were used to estimate MBC and HWEC. Compared to these approaches, we found marked benefits of laboratory and airborne data for a direct spectral quantification of MBC (but not for HWEC. This suggests specificity of spectra for MBC, usable for the determination of this important soil parameter.

  9. Wavelength selection for portable noninvasive blood component measurement system based on spectral difference coefficient and dynamic spectrum

    Science.gov (United States)

    Feng, Ximeng; Li, Gang; Yu, Haixia; Wang, Shaohui; Yi, Xiaoqing; Lin, Ling

    2018-03-01

    Noninvasive blood component analysis by spectroscopy has been a hotspot in biomedical engineering in recent years. Dynamic spectrum provides an excellent idea for noninvasive blood component measurement, but studies have been limited to the application of broadband light sources and high-resolution spectroscopy instruments. In order to remove redundant information, a more effective wavelength selection method has been presented in this paper. In contrast to many common wavelength selection methods, this method is based on sensing mechanism which has a clear mechanism and can effectively avoid the noise from acquisition system. The spectral difference coefficient was theoretically proved to have a guiding significance for wavelength selection. After theoretical analysis, the multi-band spectral difference coefficient-wavelength selection method combining with the dynamic spectrum was proposed. An experimental analysis based on clinical trial data from 200 volunteers has been conducted to illustrate the effectiveness of this method. The extreme learning machine was used to develop the calibration models between the dynamic spectrum data and hemoglobin concentration. The experiment result shows that the prediction precision of hemoglobin concentration using multi-band spectral difference coefficient-wavelength selection method is higher compared with other methods.

  10. A modification of the successive projections algorithm for spectral variable selection in the presence of unknown interferents.

    Science.gov (United States)

    Soares, Sófacles Figueredo Carreiro; Galvão, Roberto Kawakami Harrop; Araújo, Mário César Ugulino; da Silva, Edvan Cirino; Pereira, Claudete Fernandes; de Andrade, Stéfani Iury Evangelista; Leite, Flaviano Carvalho

    2011-03-09

    This work proposes a modification to the successive projections algorithm (SPA) aimed at selecting spectral variables for multiple linear regression (MLR) in the presence of unknown interferents not included in the calibration data set. The modified algorithm favours the selection of variables in which the effect of the interferent is less pronounced. The proposed procedure can be regarded as an adaptive modelling technique, because the spectral features of the samples to be analyzed are considered in the variable selection process. The advantages of this new approach are demonstrated in two analytical problems, namely (1) ultraviolet-visible spectrometric determination of tartrazine, allure red and sunset yellow in aqueous solutions under the interference of erythrosine, and (2) near-infrared spectrometric determination of ethanol in gasoline under the interference of toluene. In these case studies, the performance of conventional MLR-SPA models is substantially degraded by the presence of the interferent. This problem is circumvented by applying the proposed Adaptive MLR-SPA approach, which results in prediction errors smaller than those obtained by three other multivariate calibration techniques, namely stepwise regression, full-spectrum partial-least-squares (PLS) and PLS with variables selected by a genetic algorithm. An inspection of the variable selection results reveals that the Adaptive approach successfully avoids spectral regions in which the interference is more intense. Copyright © 2011 Elsevier B.V. All rights reserved.

  11. Silicon Nanowires for Solar Thermal Energy Harvesting: an Experimental Evaluation on the Trade-off Effects of the Spectral Optical Properties.

    Science.gov (United States)

    Sekone, Abdoul Karim; Chen, Yu-Bin; Lu, Ming-Chang; Chen, Wen-Kai; Liu, Chia-An; Lee, Ming-Tsang

    2016-12-01

    Silicon nanowire possesses great potential as the material for renewable energy harvesting and conversion. The significantly reduced spectral reflectivity of silicon nanowire to visible light makes it even more attractive in solar energy applications. However, the benefit of its use for solar thermal energy harvesting remains to be investigated and has so far not been clearly reported. The purpose of this study is to provide practical information and insight into the performance of silicon nanowires in solar thermal energy conversion systems. Spectral hemispherical reflectivity and transmissivity of the black silicon nanowire array on silicon wafer substrate were measured. It was observed that the reflectivity is lower in the visible range but higher in the infrared range compared to the plain silicon wafer. A drying experiment and a theoretical calculation were carried out to directly evaluate the effects of the trade-off between scattering properties at different wavelengths. It is clearly seen that silicon nanowires can improve the solar thermal energy harnessing. The results showed that a 17.8 % increase in the harvest and utilization of solar thermal energy could be achieved using a silicon nanowire array on silicon substrate as compared to that obtained with a plain silicon wafer.

  12. A Hybrid Multiple-Criteria Decision-Making Approach for Photovoltaic Solar Plant Location Selection

    OpenAIRE

    Amy H. I. Lee; He-Yau Kang; You-Jyun Liou

    2017-01-01

    Due to decaying fossil resource and increasing environmental consciousness, the demand of renewable energy resources is escalating these days. Photovoltaic solar energy is one of the most popular renewable energy resources in places where sunlight is abundant. The selection of a desirable location for constructing a photovoltaic solar plant is the first and one of the most important stages in the plant construction to provide a long-term energy production. In this paper, a comprehensive multip...

  13. Reconstruction of total and spectral solar irradiance from 1974 to 2013 based on KPVT, SoHO/MDI, and SDO/HMI observations

    Science.gov (United States)

    Yeo, K. L.; Krivova, N. A.; Solanki, S. K.; Glassmeier, K. H.

    2014-10-01

    Context. Total and spectral solar irradiance are key parameters in the assessment of solar influence on changes in the Earth's climate. Aims: We present a reconstruction of daily solar irradiance obtained using the SATIRE-S model spanning 1974 to 2013 based on full-disc observations from the KPVT, SoHO/MDI, and SDO/HMI. Methods: SATIRE-S ascribes variation in solar irradiance on timescales greater than a day to photospheric magnetism. The solar spectrum is reconstructed from the apparent surface coverage of bright magnetic features and sunspots in the daily data using the modelled intensity spectra of these magnetic structures. We cross-calibrated the various data sets, harmonizing the model input so as to yield a single consistent time series as the output. Results: The model replicates 92% (R2 = 0.916) of the variability in the PMOD TSI composite including the secular decline between the 1996 and 2008 solar cycle minima. The model also reproduces most of the variability in observed Lyman-α irradiance and the Mg II index. The ultraviolet solar irradiance measurements from the UARS and SORCE missions are mutually consistent up to about 180 nm before they start to exhibit discrepant rotational and cyclical variability, indicative of unresolved instrumental effects. As a result, the agreement between model and measurement, while relatively good below 180 nm, starts to deteriorate above this wavelength. As with earlier similar investigations, the reconstruction cannot reproduce the overall trends in SORCE/SIM SSI. We argue, from the lack of clear solar cycle modulation in the SIM record and the inconsistency between the total flux recorded by the instrument and TSI, that unaccounted instrumental trends are present. Conclusions: The daily solar irradiance time series is consistent with observations from multiple sources, demonstrating its validity and utility for climate models. It also provides further evidence that photospheric magnetism is the prime driver of

  14. Automated spectral zones selection methodology for diffusion theory data preparation for pebble bed reactor analysis

    Science.gov (United States)

    Mphahlele, Ramatsemela

    A methodology is developed for the determination of the optimum spectral zones in Pebble Bed Reactors (PBR). In this work a spectral zone is defined as a zone made up of a number of nodes whose characteristics are collectively similar and that are assigned the same few-group diffusion constants. In other words the spectral zones are the regions over which the few-group diffusion parameters are generated. The identification of spectral boundaries is treated as an optimization problem. It is solved by systematically and simultaneously repositioning all zone boundaries to achieve the global minimum error between the reference transport solution (MCNP) and the diffusion code solution (NEM). The objective function for the optimization algorithm is the total reaction rate error, which is defined as the sum of the leakage, absorption and fission reaction rates error in each zone. An iterative determination of group-dependent bucklings is incorporated into the methodology to properly account for spectral effects of neighboring zones. A preferred energy group structure has also been chosen. This optimization approach with the reference transport solution has proved to be accurate and consistent, however the computational effort required to complete the optimization process is significant. Thus a more practical methodology is also developed for the determination of the spectral zones in PBRs. The reactor physics characteristics of the spectral zones have been studied to understand the nature of the spectral zone boundaries. The practical tool involves the use of spectral indices based on few-group diffusion theory whole core calculations. With this methodology, there is no need to first have a reference transport solution. It is shown that the diffusion-theory coarse group fluxes and the effective multiplication factor computed using zones based on the practical index agrees within a narrow tolerance with those of the reference approach. Therefore the "practical" index

  15. Spectral Characteristics of Selected Hermatypic Corals from Gulf of Kachchh, India

    Science.gov (United States)

    Chaudhury, N. Ray

    2012-07-01

    Hermatypic, scleractinian corals are the most important benthic substrates in a coral reef ecosystem. The existing, high (spatial) resolution, broad-band, multi-spectral, space-borne sensors have limited capability to spatially detect and spectrally discriminate coral substrates. In situ hyperspectral signatures of eight coral targets were collected with the help of Analytical Spectral Devices FieldSpec spectroradiometer from Paga and Laku Point reefs of Gulf of Kachchh, India to study the spectral behaviour of corals. The eight coral targets consisted of seven live corals representing four distinct colony morphologies and one bleached coral target. The coral spectra were studied over a continuous range of 350 to 1350 nm. The corals strongly reflected in the NIR and MIR regions with regional central maximas located at 820 and 1070 nm respectively. In the visible region the live coral spectra conformed to "brown mode" of coral reflectance with triple-peaked pattern at 575, 600 and 650 nm. All coral spectra are characterized with two distinct absorption features: chlorophyll absorption at 675 nm and water absorption at 975 nm. The live and the bleached corals get distinguished in the visible region over 400 to 600 nm region. Water column over the targets modifies the spectral shape and magnitude. First and second-order derivatives help in identifying spectral windows to distinguish live and bleached corals.

  16. SPECTRAL CHARACTERISTICS OF SELECTED HERMATYPIC CORALS FROM GULF OF KACHCHH, INDIA

    Directory of Open Access Journals (Sweden)

    N. Ray Chaudhury

    2012-07-01

    Full Text Available Hermatypic, scleractinian corals are the most important benthic substrates in a coral reef ecosystem. The existing, high (spatial resolution, broad-band, multi-spectral, space-borne sensors have limited capability to spatially detect and spectrally discriminate coral substrates. In situ hyperspectral signatures of eight coral targets were collected with the help of Analytical Spectral Devices FieldSpec spectroradiometer from Paga and Laku Point reefs of Gulf of Kachchh, India to study the spectral behaviour of corals. The eight coral targets consisted of seven live corals representing four distinct colony morphologies and one bleached coral target. The coral spectra were studied over a continuous range of 350 to 1350 nm. The corals strongly reflected in the NIR and MIR regions with regional central maximas located at 820 and 1070 nm respectively. In the visible region the live coral spectra conformed to "brown mode" of coral reflectance with triple-peaked pattern at 575, 600 and 650 nm. All coral spectra are characterized with two distinct absorption features: chlorophyll absorption at 675 nm and water absorption at 975 nm. The live and the bleached corals get distinguished in the visible region over 400 to 600 nm region. Water column over the targets modifies the spectral shape and magnitude. First and second-order derivatives help in identifying spectral windows to distinguish live and bleached corals.

  17. Design and optimization of nanoparticle-pigmented solar selective absorber coatings for high-temperature concentrating solar thermal systems

    Science.gov (United States)

    Wang, Xiaoxin; Yu, Xiaobai; Fu, Sidan; Lee, Eldred; Kekalo, Katerina; Liu, Jifeng

    2018-01-01

    We present a systematic approach for the design and optimization of nanoparticle-pigmented solar selective absorbers for operation at 750 °C. Using the scattering and absorption cross-sections calculated by Lorenz-Mie scattering theory as input, we employ a four-flux radiative transfer method to investigate the solar selectivity mechanism and optimize the optical-to-thermal conversion efficiency (ηtherm) as a function of the metallic nanoparticle material, the nanoparticle diameter, the volume fraction, and the coating thickness. Among the nanoparticle material candidates in this study, C54-TiSi2 is the best option with an optimized ηtherm = 87.0% for a solar concentration ratio of C = 100 and ηtherm = 94.4% for C = 1000 at 750 °C. NiSi is also a promising candidate comparable to TiSi2 in thermal efficiency. Experimentally, an un-optimized 200 nm-diameter TiSi2 nanoparticle-silicone solar selective coating has already achieved ηtherm = 89.8% for C = 1000 at 750 °C. This performance is consistent with the theoretical model and close to the thermal efficiency of the commercial Pyromark 2500 coatings (90.1%). We also demonstrate that Ni/NiSi core-shell structures embedded in the SiO1.5 matrix is thermally stable at 750 °C for 1000 h in air. These results indicate that silicide cermet coatings are promising to achieve high optical performance and high temperature thermal stability simultaneously.

  18. Solar selective performance of metal nitride/oxynitride based magnetron sputtered thin film coatings: a comprehensive review

    Science.gov (United States)

    Ibrahim, Khalil; Taha, Hatem; Mahbubur Rahman, M.; Kabir, Humayun; Jiang, Zhong-Tao

    2018-03-01

    Since solar-thermal collectors are considered to be the most direct way of converting solar energy into usable forms, in the last few years growing attention has been paid to the development of transition metal nitride and metal oxynitride based thin film selective surfaces for solar-thermal collectors, in order to harvest more solar energy. A solar-thermal energy system, generally, shows very high solar absorption of incident solar radiation from the solar-thermal collectors in the visible range (0.3 to 2.5 μm) and extremely low thermal losses through emission (or high reflection) in the infrared region (≥2.5 μm). The efficiency of a solar-thermal energy conversion system can be improved by the use of solar selective surfaces consisting of novel metallic nanoparticles embedded in metal nitride/oxynitride systems. In order to enhance the effectiveness of solar-thermal devices, solar selective surfaces with high thermal stability are a prerequisite. Over the years, substantial efforts have been made in the field of solar selective surfaces to attain higher solar absorptance and lower thermal emittance in high temperature (above 400 °C) applications. In this article, we review the present state-of-the-art transition metal nitride and/or oxynitride based vacuum sputtered nanostructured thin film coatings, with respect to their optical and solar selective surface applications. We have also summarized the solar selectivity data from recently published investigations, including discussion on some potential applications for these materials.

  19. On the Role of Solar Wind Discontinuities in the ULF Power Spectral Density at the Earth's Outer Radiation Belt: a Case Study

    Science.gov (United States)

    Lago, A.; Alves, L. R.; Braga, C. R.; Mendonca, R. R. S.; Jauer, P. R.; Medeiros, C.; Souza, V. M. C. E. S.; Mendes, O., Jr.; Marchezi, J.; da Silva, L.; Vieira, L.; Rockenbach, M.; Sibeck, D. G.; Kanekal, S. G.; Baker, D. N.; Wygant, J. R.; Kletzing, C.

    2016-12-01

    The solar wind incident upon the Earth's magnetosphere can produce either enhancement, depletion or no change in the flux of relativistic electrons at the outer radiation belt. During geomagnetic storms progress, solar wind parameters may change significantly, and occasionally relativistic electron fluxes at the outer radiation belt show dropouts in a range of energy and L-shells. Wave-particle interactions observed within the Van Allen belts have been claimed to play a significant role in energetic particle flux changes. The relation between changes on the solar wind parameters and the radiation belt is still a hot topic nowadays, particularly the role played by the solar wind on sudden electron flux decreases. The twin satellite Van Allen Probes measured a relativistic electron flux dropout concurrent to broad band Ultra-low frequency (ULF) waves, i.e. from 1 mHz to 10 Hz, on October 2, 2013. Magnetic field and plasma data from both ACE and WIND satellites allowed the characterization of this event as being an interplanetary coronal mass ejection in conjunction with shock. The interaction of this event with the Earth's magnetosphere was modeled using a global magnetohydrodynamic simulation and the magnetic field perturbation deep in magnetosphere could be analyzed from the model outputs. Results show the contribution of time-varying solar wind parameters to the generation of ULF waves. The power spectral densities, as a function of L-shell, were evaluated considering changes in the input parameters, e.g. magnitude and duration of dynamic pressure and magnetic field. The modeled power spectral densities are compared with Van Allen Probes data. The results provide us a clue on the solar wind characteristics that might be able to drive ULF waves in the inner magnetosphere, and also which wave modes are expected to be excited under a specific solar wind driving.

  20. Selecting Solar: Insights into Residential Photovoltaic (PV) Quote Variation

    Energy Technology Data Exchange (ETDEWEB)

    Davidson, Carolyn [National Renewable Energy Lab. (NREL), Golden, CO (United States); Margolis, Robert [National Renewable Energy Lab. (NREL), Golden, CO (United States)

    2015-10-01

    Before investing in a system, a prospective PV customer must not only have initial concept 'buy in,' but also be able to evaluate the tradeoffs associated with different system parameters. Prospective customers might need to evaluate disparate costs for each system attribute by comparing multiple bids. The difficulty of making such an evaluation with limited information can create a cognitive barrier to proceeding with the investment. This analysis leverages recently available data from EnergySage, an online solar marketplace, to offer the first data-driven characterization of quote variation faced by prospective PV customers, lending early insight into the decisions customers face once they have initial buy-in.

  1. UARS Solar-Stellar Irradiance Comparison Experiment (SOLSTICE) Level 3BS V018 (UARSO3BS) at GES DISC

    Data.gov (United States)

    National Aeronautics and Space Administration — The Solar-Stellar Irradiance Comparison Experiment (SOLSTICE) Level 3BS data product consists of daily, 1 nm resolution, solar spectral irradiances and selected...

  2. Optoelectronic simulation of GaAs solar cells with angularly selective filters

    International Nuclear Information System (INIS)

    Kraus, Tobias; Höhn, Oliver; Hauser, Hubert; Bläsi, Benedikt

    2014-01-01

    We discuss the influence of angularly selective filters on thin film gallium arsenide solar cells. For this reason, the detailed balance model was refined to fit our needs with respect to Auger recombination, reflection, transmission, and realistic absorption. For calculating real systems, an approach was made to include optical effects of angularly selective filters into electron-hole dynamic equations implemented in PC1D, a one dimensional solar cell calculation tool. With this approach, we find a relative V oc increase of 5% for an idealized 100 nm GaAs cell, including Auger recombination

  3. A synthetic method of solar spectrum based on LED

    Science.gov (United States)

    Wang, Ji-qiang; Su, Shi; Zhang, Guo-yu; Zhang, Jian

    2017-10-01

    A synthetic method of solar spectrum which based on the spectral characteristics of the solar spectrum and LED, and the principle of arbitrary spectral synthesis was studied by using 14 kinds of LED with different central wavelengths.The LED and solar spectrum data were selected by Origin Software firstly, then calculated the total number of LED for each center band by the transformation relation between brightness and illumination and Least Squares Curve Fit in Matlab.Finally, the spectrum curve of AM1.5 standard solar spectrum was obtained. The results met the technical indexes of the solar spectrum matching with ±20% and the solar constant with >0.5.

  4. Development of optical tools for the characterization of selective solar absorber at elevated temperature

    Science.gov (United States)

    Giraud, Philemon; Braillon, Julien; Delord, Christine; Raccurt, Olivier

    2016-05-01

    Durability of solar components for CSP (Concentrated Solar Power Plant) technologies is a key point to lower cost and ensure their large deployment. These technologies concentrated the solar radiation by means of mirrors on a receiver tube where it is collected as thermal energy. The absorbers are submitted to strong environmental constraints and the degradation of their optical properties (emittance and solar absorbance) have a direct impact on performance. The objective is to develop new optical equipment for characterization of this solar absorber in condition of use that is to say in air and at elevated temperature. In this paper we present two new optical test benches developed for optical characterization of solar absorbers in condition of use up to 800°C. The first equipment is an integrated sphere with heated sample holder which measures the hemispherical reflectance between 280 and 2500 nm to calculate the solar absorbance at high temperature. The second optical test bench measures the emittance of samples up to 1000°C in the range of 1.25 to 28.57 µm. Results of high temperature measurements on a series of metallic absorbers with selective coating and refractory material for high thermal receiver are presented.

  5. Spectrally selective molecular doped solids: spectroscopy, photophysics and their application to ultrafast optical pulse processing

    International Nuclear Information System (INIS)

    Galaup, Jean-Pierre

    2005-01-01

    The persistent spectral hole-burning (PSHB) phenomenon observed in molecular doped polymers cooled down to liquid helium temperatures allows the engraving of spectral structures in the inhomogeneous absorption profile of the material. This phenomenon known since 1974 has became a fruitful field for the study of the intimacy of complex molecular systems in the solid state, revealing high-resolution spectroscopy, photophysics, photochemistry and dynamics of molecular doped amorphous media, organic as well as inorganic. A PSHB molecular doped solid can be programmed in spectral domain and therefore, it can be converted in an optical processor capable to achieve user-defined optical functions. Some aspects of this field are illustrated in the present paper. An application is presented where a naphthalocyanine doped polymer film is used in a demonstrative experiment to prove that temporal aberration free re-compression of ultra-short light pulses is feasible. Perspectives for the coherent control of light fields or photochemical processes are also evoked

  6. Spectrally selective molecular doped solids: spectroscopy, photophysics and their application to ultrafast optical pulse processing

    Energy Technology Data Exchange (ETDEWEB)

    Galaup, Jean-Pierre [Laboratoire Aime Cotton, CNRS UPR 3321, Ba-hat t. 505, 91405 Orsay cedex (France)]. E-mail: jean-pierre.galaup@lac.u-psud.fr

    2005-04-15

    The persistent spectral hole-burning (PSHB) phenomenon observed in molecular doped polymers cooled down to liquid helium temperatures allows the engraving of spectral structures in the inhomogeneous absorption profile of the material. This phenomenon known since 1974 has became a fruitful field for the study of the intimacy of complex molecular systems in the solid state, revealing high-resolution spectroscopy, photophysics, photochemistry and dynamics of molecular doped amorphous media, organic as well as inorganic. A PSHB molecular doped solid can be programmed in spectral domain and therefore, it can be converted in an optical processor capable to achieve user-defined optical functions. Some aspects of this field are illustrated in the present paper. An application is presented where a naphthalocyanine doped polymer film is used in a demonstrative experiment to prove that temporal aberration free re-compression of ultra-short light pulses is feasible. Perspectives for the coherent control of light fields or photochemical processes are also evoked.

  7. Core and Wing Densities of Asymmetric Coronal Spectral Profiles: Implications for the Mass Supply of the Solar Corona

    Science.gov (United States)

    Patsourakos, S.; Klimchuk, J. A.; Young, P. R.

    2014-01-01

    Recent solar spectroscopic observations have shown that coronal spectral lines can exhibit asymmetric profiles, with enhanced emissions at their blue wings. These asymmetries correspond to rapidly upflowing plasmas at speeds exceeding approximately equal to 50 km per sec. Here, we perform a study of the density of the rapidly upflowing material and compare it with that of the line core that corresponds to the bulk of the plasma. For this task, we use spectroscopic observations of several active regions taken by the Extreme Ultraviolet Imaging Spectrometer of the Hinode mission. The density sensitive ratio of the Fe(sub XIV) lines at 264.78 and 274.20 Angstroms is used to determine wing and core densities.We compute the ratio of the blue wing density to the core density and find that most values are of order unity. This is consistent with the predictions for coronal nanoflares if most of the observed coronal mass is supplied by chromospheric evaporation driven by the nanoflares. However, much larger blue wing-to-core density ratios are predicted if most of the coronal mass is supplied by heated material ejected with type II spicules. Our measurements do not rule out a spicule origin for the blue wing emission, but they argue against spicules being a primary source of the hot plasma in the corona. We note that only about 40% of the pixels where line blends could be safely ignored have blue wing asymmetries in both Fe(sub XIV) lines. Anticipated sub-arcsecond spatial resolution spectroscopic observations in future missions could shed more light on the origin of blue, red, and mixed asymmetries.

  8. Preparation of a TiMEMO nanocomposite by the sol-gel method and its application in coloured thickness insensitive spectrally selective (TISS) coatings

    Energy Technology Data Exchange (ETDEWEB)

    Japelj, Bostjan; Vuk, Angela Surca; Orel, Boris; Perse, Lidija Slemenik; Jerman, Ivan [National Institute of Chemistry, Hajdrihova 19, SI-1000 Ljubljana (Slovenia); Kovac, Janez [Jozef Stefan Institute, Jamova 39, SI-1000 Ljubljana (Slovenia)

    2008-09-15

    An organic-inorganic nanocomposite was prepared via sol-gel processing from 3-(trimethoxysilyl)propyl methacrylate (MAPTMS) and titanium(IV) isopropoxide (TIP) precursors (TiMEMO) in the form of a viscous resin, and used as a binder for the preparation of coloured thickness insensitive spectrally selective (TISS) paints and corresponding solar absorber coatings. The spectral selectivity of TiMEMO-based TISS paints was optimized by varying the concentrations of binder and different pigments: black, coloured (red, green and blue) and aluminium flakes, the latter imparting low thermal emittance, which was correlated to the presence of titanium in the TiMEMO sol-gel host. The formation and the ensuing structure of the sol-gel TiMEMO hybrid was studied in detail and the nanocomposite structure of the TiMEMO binder formed was assessed from infrared and {sup 29}Si NMR measurements, which confirmed the formation of Ti-O-Si linkages established after the hydrolysed precursors condensed into a compliant resinous material. XRD measurements provided additional information about the existence of small coherent domains of silsesquioxane units in the sol-gel host. The abrasion resistance of the non-pigmented TiMEMO binder deposited in thin film form on a PMMA substrate was assessed by the Taber test, and its hardness compared with other resin binders which have been used for making TISS paint coatings. The surface properties of the non-pigmented TiMEMO binder and the ensuing TISS paint coatings were determined from contact angle measurements. The results showed that the water contact angles of non-pigmented TiMEMO binder increased from 70 to 125-135 for the corresponding pigmented TISS paint coatings, inferring the influence of surface roughness on surface energy in the presence of pigments. SEM measurements revealed a striking similarity in the surface morphology of the TISS paint coatings with some other surfaces exhibiting the Lotus effect. (author)

  9. Monitoring of Water Spectral Pattern Reveals Differences in Probiotics Growth When Used for Rapid Bacteria Selection.

    Directory of Open Access Journals (Sweden)

    Aleksandar Slavchev

    Full Text Available Development of efficient screening method coupled with cell functionality evaluation is highly needed in contemporary microbiology. The presented novel concept and fast non-destructive method brings in to play the water spectral pattern of the solution as a molecular fingerprint of the cell culture system. To elucidate the concept, NIR spectroscopy with Aquaphotomics were applied to monitor the growth of sixteen Lactobacillus bulgaricus one Lactobacillus pentosus and one Lactobacillus gasseri bacteria strains. Their growth rate, maximal optical density, low pH and bile tolerances were measured and further used as a reference data for analysis of the simultaneously acquired spectral data. The acquired spectral data in the region of 1100-1850nm was subjected to various multivariate data analyses - PCA, OPLS-DA, PLSR. The results showed high accuracy of bacteria strains classification according to their probiotic strength. Most informative spectral fingerprints covered the first overtone of water, emphasizing the relation of water molecular system to cell functionality.

  10. Systems and methods for selective detection and imaging in coherent Raman microscopy by spectral excitation shaping

    Science.gov (United States)

    Xie, Xiaoliang Sunney; Freudiger, Christian; Min, Wei

    2016-03-15

    A microscopy imaging system is disclosed that includes a light source system, a spectral shaper, a modulator system, an optics system, an optical detector and a processor. The light source system is for providing a first train of pulses and a second train of pulses. The spectral shaper is for spectrally modifying an optical property of at least some frequency components of the broadband range of frequency components such that the broadband range of frequency components is shaped producing a shaped first train of pulses to specifically probe a spectral feature of interest from a sample, and to reduce information from features that are not of interest from the sample. The modulator system is for modulating a property of at least one of the shaped first train of pulses and the second train of pulses at a modulation frequency. The optical detector is for detecting an integrated intensity of substantially all optical frequency components of a train of pulses of interest transmitted or reflected through the common focal volume. The processor is for detecting a modulation at the modulation frequency of the integrated intensity of substantially all of the optical frequency components of the train of pulses of interest due to the non-linear interaction of the shaped first train of pulses with the second train of pulses as modulated in the common focal volume, and for providing an output signal for a pixel of an image for the microscopy imaging system.

  11. Selective production of hydrogen peroxide and oxidation of hydrogen sulfide in an unbiased solar photoelectrochemical cell

    DEFF Research Database (Denmark)

    Zong, Xu; Chen, Hongjun; Seger, Brian

    2014-01-01

    A solar-to-chemical conversion process is demonstrated using a photoelectrochemical cell without external bias for selective oxidation of hydrogen sulfide (H2S) to produce hydrogen peroxide (H2O2) and sulfur (S). The process integrates two redox couples anthraquinone/anthrahydroquinone and I−/I3...

  12. Spray pyrolytically grown NiAlOx cermets for solar thermal selective ...

    Indian Academy of Sciences (India)

    -cermet-layer structure, because of the ease of fabrication, is the most suitable for a cermet solar selective absorber [7]. Figure 11. Multilayer structure composed of (60/40) nickel to aluminium (1st layer) and (60/40 + 10/90) nickel to aluminium ( ...

  13. A figure of merit for selective absorbers in flat plate solar water heaters

    CSIR Research Space (South Africa)

    Roberts, DE

    2013-12-01

    Full Text Available We derive from first principles an analytical expression for a figure of merit (FM) for a selective solar absorber in a single glazed flat plate water heater. We first show that the efficiency of a collector with an absorber with absorptance α...

  14. The characterisation of selective proton damage on GaAs solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Aliyu, Y.H. (School of Electrical, Electronic and Systems Engineering, Wales Univ., Cardiff (United Kingdom)); Morgan, D.V. (School of Electrical, Electronic and Systems Engineering, Wales Univ., Cardiff (United Kingdom)); Bunce, R.W. (School of Electrical, Electronic and Systems Engineering, Wales Univ., Cardiff (United Kingdom))

    1993-01-16

    Selective ion bombardment damage was induced on n/n[sup +] GaAs Schottky barrier solar cell structure using several proton energies and doses. The damage in the surface, interface, and the bulk regions were characterised by I-V, C-V, and thermally stimulated current technique (TSC). A correlation between the selective damages and the nature of the defects and their location was obtained. (orig.)

  15. A Hybrid Multiple-Criteria Decision-Making Approach for Photovoltaic Solar Plant Location Selection

    Directory of Open Access Journals (Sweden)

    Amy H. I. Lee

    2017-01-01

    Full Text Available Due to decaying fossil resource and increasing environmental consciousness, the demand of renewable energy resources is escalating these days. Photovoltaic solar energy is one of the most popular renewable energy resources in places where sunlight is abundant. The selection of a desirable location for constructing a photovoltaic solar plant is the first and one of the most important stages in the plant construction to provide a long-term energy production. In this paper, a comprehensive multiple-criteria decision-making model, which incorporates the interpretive structural modeling (ISM, fuzzy analytic network process (FANP and VIKOR (VlseKriterijumska OptimizacijaI Kompromisno Resenje in Serbian,meaning multi-criteria optimization and compromise solution, is proposed to select the most suitable photovoltaic solar plant location. The ISM is applied first to determine the interrelationships among the criteria and among the sub-criteria,andtheresults are used to construct a decision-making network. The FANP is applied next to solve the network and to calculate the importance weights of the sub-criteria. Finally, the VIKOR is adopted to determine the ranking of the photovoltaic solar plant locations. The proposed model is applied in a case study in evaluating photovoltaic solar plant locations in Taiwan. By applying the proposed model, decision makers can have a better thinking process and make more appropriate decisions justifiably.

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

    International Nuclear Information System (INIS)

    Desai, Nishith B.; Bandyopadhyay, Santanu

    2016-01-01

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

  17. Investigation of spectral distribution and variation of irradiance with the passage time of CSI lamps which constitute a solar simulator; Solar simulator ni shiyosuru CSI lamp no supekutoru bunpu, hosha shodo no keiji henka ni kansuru chosa

    Energy Technology Data Exchange (ETDEWEB)

    Sugiyama, T.; Yamada, T.; Noguchi, T. [Japan Quality Assurance Organization, Tokyo (Japan)

    1997-11-25

    Study was made on time-variation of the performance of CSI lamps for solar simulators. In order to accurately evaluate the standard heat collection performance of solar systems in a room, MITI installed an artificial solar light source in the Solar Techno-Center of Japan Quality Assurance Organization for trial use and evaluation. CSI lamp is superior in durability, and can simulate the solar light in the daytime. The light source is composed of 72 metal halide lamps of 1kW arranged in a plane of 3.5times3.5m. The study result on time-variation of a spectral distribution and irradiance by intermittent switching of lamps showed a sufficient durability of 2000h. To ensure the accuracy of a solar heat collector measurement system enough, periodic calibration is being carried out using reference goods. To ensure the reliability and stability for a switching system, periodic maintenance of a power source, stabilizer and electric system is also being carried out in addition to CSI lamps. The stable irradiance and accuracy are being kept by such maintenance and periodic exchange of lamps. 6 figs., 4 tabs.

  18. An automatic measuring system for mapping of spectral and angular dependence of direct and diffuse solar radiation; Et automatisk maalesystem for kartlegging av vinkel- og spektralfordeling av direkte og diffus solstraaling

    Energy Technology Data Exchange (ETDEWEB)

    Grandum, Oddbjoern

    1997-12-31

    In optimizing solar systems, it is necessary to know the spectral and angular dependence of the radiation. The general nonlinear character of most solar energy systems accentuates this. This thesis describes a spectroradiometer that will measure both the direct component of the solar radiation and the angular dependence of the diffuse component. Radiation from a selected part of the sky is transported through a movable set of tube sections on to a stationary set of three monochromators with detectors. The beam transport system may effectively be looked upon as a single long tube aimed at a particular spot in the sky. The half value of the effective opening angle is 1.3{sup o} for diffuse radiation and 2.8{sup o} for direct radiation. The whole measurement process is controlled and operated by a PC and normally runs without manual attention. The instrument is built into a caravan. The thesis describes in detail the experimental apparatus, calibration and measurement accuracies. To map the diffuse radiation, one divides the sky into 26 sectors of equal solid angle. A complete measurement cycle is then made at a random point within each sector. These measurements are modelled by fitting to spherical harmonics, enforcing symmetry around the solar direction and the horizontal plane. The direct radiation is measured separately. Also the circumsolar sector is given special treatment. The measurements are routinely checked against global radiation measured in parallel by a standard pyranometer, and direct solar radiation by a pyrheliometer. An extensive improvement programme is being planned for the instrument, including the use of a photomultiplier tube to measure the UV part of the spectrum, a diode array for the 400-1100 nm range, and use of a Ge diode for the 1000-1900 nm range. 78 refs., 90 figs., 31 tabs.

  19. Spectral Counting Approach to Measure Selectivity of High-Resolution LC-MS Methods for Environmental Analysis.

    Science.gov (United States)

    Renaud, Justin B; Sabourin, Lyne; Topp, Edward; Sumarah, Mark W

    2017-03-07

    Advances in high-resolution mass spectrometers have allowed for the development of nontargeted screening methods, where data sets can be archived and retrospectively mined as new environmental contaminants are identified. We have developed a spectral counting approach to calculate the selectivities of LC-MS acquisition modes taking mass accuracy, sample matrix, and the analyte properties into account. The selectivities of high-resolution MS (HRMS) alone or in combination with all-ion-fragmentation (AIF), data-independent-acquisition (DIA), and data-dependent-acquisition (DDA) modes, performed on a Q-Exactive Orbitrap were compared by retrospectively screening surface water samples for 95 pharmaceuticals. Samples were reanalyzed using targeted LC-MS/MS to confirm the accuracy of each acquisition method and to quantitate the 29 putatively detected drugs. LC-HRMS provided the lowest calculated selectivities and accordingly produced the highest number of false positives (6). In contrast, DDA provided the highest selectivities, yielding only one false positive; however, it was bias toward the most intense signals resulting in the detection of only 10 compounds. AIF had lower selectivities than traditional LC-MS/MS, produced one false positive and did not detect 6 confirmed compounds. Because of the high-quality archived data, DIA selectivities were better than traditional LC-MS/MS, showed no bias toward the most intense signals, achieved low limits of detection, and confidently detected the greatest number of pharmaceuticals (22) with only one false positive. This spectral counting method can be used across different instrument platforms or samples and provides a robust and empirical estimation of selectivities to give more confident detection of trace analytes.

  20. Improving Solar Soft X-Ray (SXR) Irradiance Results from Broadband Photometers with New SXR Spectral Measurements from a CubeSat

    Science.gov (United States)

    Woods, T. N.; Caspi, A.; Chamberlin, P. C.; Didkovsky, L. V.; Eparvier, F. G.; Jones, A. R.; Mason, J. P.; Moore, C. S.; Solomon, S. C.; Viereck, R. A.

    2016-12-01

    There are four decades of broadband soft X-ray (SXR) measurements, but these measurements cannot directly quantify the varying contributions of emission lines (bound-bound) amongst the thermal radiative recombination (free-bound) and thermal and non-thermal bremsstrahlung (free-free) continua. The Miniature X-ray Solar Spectrometer (MinXSS) CubeSat mission, that was deployed into orbit in May 2016, was designed to directly measure the SXR spectra to improve the understanding of flare energetics and for studying the SXR radiation impacts in Earth's ionosphere. The broadband SXR measurements include the two bands of 1.6-25 keV (0.05-0.8 nm) by the GOES X-Ray Sensor (XRS) since the 1970s and the even broader band of 0.2-12 keV (0.1-7 nm) from several missions, including the Yohkoh Soft X-ray Telescope (SXT, 1991-2001), Student Nitric Oxide Experiment (SNOE, 1998-2002), Thermosphere-Ionosphere-Mesosphere Energetics and Dynamics (TIMED, 2002-present), the Solar Radiation and Climate Experiment (SORCE, 2003-present), and the Solar Dynamics Observatory (SDO, 2010-present). These broadband SXR measurements have been helpful for resolving some differences between ionosphere models and measurements, but differences remain in understanding solar SXR spectral distribution and atmospheric photoelectron flux. The lack of spectral resolution in the SXR range is thought to be the culprit for most of these disagreements and is thus an underlying motivation for the MinXSS CubeSat mission. The new solar SXR spectra in the range of 0.5 to 30 keV (0.04 - 2.5 nm) from MinXSS, along with how they can improve the accuracy of the broadband SXR photometer measurements, will be presented.

  1. Selective deposition contact patterning using atomic layer deposition for the fabrication of crystalline silicon solar cells

    International Nuclear Information System (INIS)

    Cho, Young Joon; Shin, Woong-Chul; Chang, Hyo Sik

    2014-01-01

    Selective deposition contact (SDC) patterning was applied to fabricate the rear side passivation of crystalline silicon (Si) solar cells. By this method, using screen printing for contact patterning and atomic layer deposition for the passivation of Si solar cells with Al 2 O 3 , we produced local contacts without photolithography or any laser-based processes. Passivated emitter and rear-contact solar cells passivated with ozone-based Al 2 O 3 showed, for the SDC process, an up-to-0.7% absolute conversion-efficiency improvement. The results of this experiment indicate that the proposed method is feasible for conversion-efficiency improvement of industrial crystalline Si solar cells. - Highlights: • We propose a local contact formation process. • Local contact forms a screen print and an atomic layer deposited-Al 2 O 3 film. • Ozone-based Al 2 O 3 thin film was selectively deposited onto patterned silicon. • Selective deposition contact patterning method can increase cell-efficiency by 0.7%

  2. Potential of PEDOT:PSS as a hole selective front contact for silicon heterojunction solar cells.

    Science.gov (United States)

    Jäckle, Sara; Liebhaber, Martin; Gersmann, Clemens; Mews, Mathias; Jäger, Klaus; Christiansen, Silke; Lips, Klaus

    2017-05-19

    We show that the highly conductive polymer poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS) can successfully be applied as a hole selective front contact in silicon heterojunction (SHJ) solar cells. In combination with a superior electron selective heterojunction back contact based on amorphous silicon (a-Si), mono-crystalline n-type silicon (c-Si) solar cells reach power conversion efficiencies up to 14.8% and high open-circuit voltages exceeding 660 mV. Since in the PEDOT:PSS/c-Si/a-Si solar cell the inferior hybrid junction is determining the electrical device performance we are capable of assessing the recombination velocity (v I ) at the PEDOT:PSS/c-Si interface. An estimated v I of ~400 cm/s demonstrates, that while PEDOT:PSS shows an excellent selectivity on n-type c-Si, the passivation quality provided by the formation of a native oxide at the c-Si surface restricts the performance of the hybrid junction. Furthermore, by comparing the measured external quantum efficiency with optical simulations, we quantify the losses due to parasitic absorption of PEDOT:PSS and reflection of the device layer stack. By pointing out ways to better passivate the hybrid interface and to increase the photocurrent we discuss the full potential of PEDOT:PSS as a front contact in SHJ solar cells.

  3. An intense charge transfer broadband sensitized near-infrared emitting CaLaGa3S3O:Yb3+ phosphor suitable for solar spectral convertor.

    Science.gov (United States)

    Zhang, Gongguo; Liu, Chunmeng; Wang, Jing; Kuang, Xiaojun; Su, Qiang

    2011-11-21

    A near-infrared (NIR) phosphor, CaLaGa(3)S(6)O:Yb(3+), is developed as a promising solar spectral convertor for Si solar cells. The structure, photoluminescence excitation and emission spectra, concentration effect are investigated. The results show that CaLaGa(3)S(6)O:Yb(3+) has an efficient broad absorption band dominating around the 345 nm ascribing to the charge transfer state (CTS) of Yb(3+)-S(2-) and exhibits an intense NIR emission of Yb(3+) between 920 and 1150 nm, perfectly matching the maximum spectral response of Si solar cells. The NIR emission intensity of CaLaGa(3)S(6)O:Yb(3+) is 12 times as intense as that of a NIR quantum cutting phosphor Ca(2)BO(3)Cl:Ce(3+), Tb(3+), Yb(3+) (CBC) upon 4f-5d excitation of Ce(3+). These results demonstrate that the allowed CTS of Yb(3+)-S(2-) with high absorption cross-section can be an efficient and direct sensitizer harvesting UV-blue photons and greatly enhancing the NIR emission of Yb(3+) ion. © 2011 Optical Society of America

  4. Application of self-organizing feature maps to analyze the relationships between ignitable liquids and selected mass spectral ions.

    Science.gov (United States)

    Frisch-Daiello, Jessica L; Williams, Mary R; Waddell, Erin E; Sigman, Michael E

    2014-03-01

    The unsupervised artificial neural networks method of self-organizing feature maps (SOFMs) is applied to spectral data of ignitable liquids to visualize the grouping of similar ignitable liquids with respect to their American Society for Testing and Materials (ASTM) class designations and to determine the ions associated with each group. The spectral data consists of extracted ion spectra (EIS), defined as the time-averaged mass spectrum across the chromatographic profile for select ions, where the selected ions are a subset of ions from Table 2 of the ASTM standard E1618-11. Utilization of the EIS allows for inter-laboratory comparisons without the concern of retention time shifts. The trained SOFM demonstrates clustering of the ignitable liquid samples according to designated ASTM classes. The EIS of select samples designated as miscellaneous or oxygenated as well as ignitable liquid residues from fire debris samples are projected onto the SOFM. The results indicate the similarities and differences between the variables of the newly projected data compared to those of the data used to train the SOFM. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

  5. Electronic structure and spectral properties of selected trimethyl-alloxazines: Combined experimental and DFT study

    International Nuclear Information System (INIS)

    Bruszynska, Magdalena; Sikorska, Ewa; Komasa, Anna; Khmelinskii, Igor; Ferreira, Luis F.V.; Hernando, Jordi; Karolczak, Jerzy; Kubicki, Maciej; Bourdelande, Jose L.; Sikorski, Marek

    2009-01-01

    Electronic structure and S 0 -S i , T 1 -T i , and S 0 -T i transition energies and oscillator strengths were calculated using the TD-DFT method for a series of trimethyl substituted alloxazines. The general energy diagram of the excited states predicted by the calculations is generally the same in these and in other alloxazines, with the two lowest close-lying n, π * and π, π * singlet excited states, determining the photophysical properties, being isoenergetic in most cases. The theoretical predictions are compared to the experimentally determined spectral and photophysical properties.

  6. Spectral characteristics of (111 silicon with Raman selections under different states of stress

    Directory of Open Access Journals (Sweden)

    Wei Qiu

    2017-07-01

    Full Text Available (111 silicon is widely used in current microstructures. In this study, theoretical analysis shows that different states of elastic stress may result in different eigenvalues and their respective eigenvectors of the lattice dynamics secular equation. The key point in determining the spectral character is to obtain the Raman tensor corresponding to each eigenvector whose eigenvalue can be represented by a function of the stress tensor components. As examples, the wavenumber–stress factors under some specific states of stress at typical polarization configurations were determined. Finally, a calibration experiment was performed to validate the theoretical prediction.

  7. Spectral characteristics and feature selection of satellite remote sensing data for climate and anthropogenic changes assessment in Bucharest area

    Science.gov (United States)

    Zoran, Maria; Savastru, Roxana; Savastru, Dan; Tautan, Marina; Miclos, Sorin; Cristescu, Luminita; Carstea, Elfrida; Baschir, Laurentiu

    2010-05-01

    Urban systems play a vital role in social and economic development in all countries. Their environmental changes can be investigated on different spatial and temporal scales. Urban and peri-urban environment dynamics is of great interest for future planning and decision making as well as in frame of local and regional changes. Changes in urban land cover include changes in biotic diversity, actual and potential primary productivity, soil quality, runoff, and sedimentation rates, and cannot be well understood without the knowledge of land use change that drives them. The study focuses on the assessment of environmental features changes for Bucharest metropolitan area, Romania by satellite remote sensing and in-situ monitoring data. Rational feature selection from the varieties of spectral channels in the optical wavelengths of electromagnetic spectrum (VIS and NIR) is very important for effective analysis and information extraction of remote sensing data. Based on comprehensively analyses of the spectral characteristics of remote sensing data is possibly to derive environmental changes in urban areas. The information quantity contained in a band is an important parameter in evaluating the band. The deviation and entropy are often used to show information amount. Feature selection is one of the most important steps in recognition and classification of remote sensing images. Therefore, it is necessary to select features before classification. The optimal features are those that can be used to distinguish objects easily and correctly. Three factors—the information quantity of bands, the correlation between bands and the spectral characteristic (e.g. absorption specialty) of classified objects in test area Bucharest have been considered in our study. As, the spectral characteristic of an object is influenced by many factors, being difficult to define optimal feature parameters to distinguish all the objects in a whole area, a method of multi-level feature selection

  8. Strategic selection of suitable projects for hybrid solar-wind power generation systems

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Hsing Hung [Faculty of Management and Administration, Macau University of Science and Technology, Taipa, Macau (China); Kang, He-Yau [Department of Industrial Engineering and Management, National Chin-Yi University of Technology, Taiping, Taichung (China); Lee, Amy H.I. [Department of Industrial Management, Chung Hua University, Non.707, Sec. 2, WuFu Rd., Hsinchu (China)

    2010-01-15

    Because of the pressing need for maintaining a healthy environment with reasonable costs, China is moving toward the trend for generating electricity from renewable resources. Both solar energy and wind power have received a tremendous attention from private associations, political groups, and electric power companies to generate power on a large scale. A drawback is their unpredictable nature and dependence on weather. Fortunately, the problems can be partially tackled by using the strengths of one source to overcome the weakness of the other. Especially, a large fraction of the solar resource is available at times of peak electrical load. However, the complexity of using two different resources together makes the hybrid solar-wind generation systems more difficult to analyze. Accordingly, this paper first briefly introduces the solar-wind generation system and next develops its critical success criteria. Then, a fuzzy analytic hierarchy process associated with benefits, opportunities, costs and risks, is proposed to help select a suitable solar-wind power generation project. (author)

  9. Role of the Selective Contacts in the Performance of Lead Halide Perovskite Solar Cells.

    Science.gov (United States)

    Juarez-Perez, Emilio J; Wuβler, Michael; Fabregat-Santiago, Francisco; Lakus-Wollny, Kerstin; Mankel, Eric; Mayer, Thomas; Jaegermann, Wolfram; Mora-Sero, Ivan

    2014-02-20

    The effect of electron- and hole-selective contacts in the final cell performance of hybrid lead halide perovskite, CH3NH3PbI3, solar cells has been systematically analyzed by impedance spectroscopy. Complete cells with compact TiO2 and spiro-OMeTAD as electron- and hole-selective contacts have been compared with incomplete cells without one or both selective contacts to highlight the specific role of each contact. It has been described how selective contacts contribute to enhance the cell FF and how the hole-selective contact is mainly responsible for the high Voc in this kind of device. We have determined that the recombination rate is mainly governed by the selective contacts. This fact has important implication for the future optimization of perovskite solar cells. Finally, we have developed a method to analyze the results obtained, and it has been applied for three different electron-selecting materials: TiO2, ZnO, and CdS.

  10. Tantalum Nitride Electron-Selective Contact for Crystalline Silicon Solar Cells

    KAUST Repository

    Yang, Xinbo

    2018-04-19

    Minimizing carrier recombination at contact regions by using carrier‐selective contact materials, instead of heavily doping the silicon, has attracted considerable attention for high‐efficiency, low‐cost crystalline silicon (c‐Si) solar cells. A novel electron‐selective, passivating contact for c‐Si solar cells is presented. Tantalum nitride (TaN x ) thin films deposited by atomic layer deposition are demonstrated to provide excellent electron‐transporting and hole‐blocking properties to the silicon surface, due to their small conduction band offset and large valence band offset. Thin TaNx interlayers provide moderate passivation of the silicon surfaces while simultaneously allowing a low contact resistivity to n‐type silicon. A power conversion efficiency (PCE) of over 20% is demonstrated with c‐Si solar cells featuring a simple full‐area electron‐selective TaNx contact, which significantly improves the fill factor and the open circuit voltage (Voc) and hence provides the higher PCE. The work opens up the possibility of using metal nitrides, instead of metal oxides, as carrier‐selective contacts or electron transport layers for photovoltaic devices.

  11. UV-Vis-NIR luminescence properties and energy transfer mechanism of LiSrPO4:Eu2+, Pr3+ suitable for solar spectral convertor.

    Science.gov (United States)

    Chen, Yan; Wang, Jing; Liu, Chunmeng; Tang, Jinke; Kuang, Xiaojun; Wu, Mingmei; Su, Qiang

    2013-02-11

    An efficient near-infrared (NIR) phosphor LiSrPO(4):Eu(2+), Pr(3+) is synthesized by solid-state reaction and systematically investigated using x-ray diffraction, diffuse reflection spectrum, photoluminescence spectra at room temperature and 3 K, and the decay curves. The UV-Vis-NIR energy transfer mechanism is proposed based on these results. The results demonstrate Eu(2+) can be an efficient sensitizer for harvesting UV photon and greatly enhancing the NIR emission of Pr(3+) between 960 and 1060 nm through efficient energy feeding by allowed 4f-5d absorption of Eu(2+) with high oscillator strength. Eu(2+)/Pr(3+) may be an efficient donor-acceptor pair as solar spectral converter for Si solar cells.

  12. Industrially feasible, dopant-free, carrier-selective contacts for high-efficiency silicon solar cells

    KAUST Repository

    Yang, Xinbo

    2017-05-31

    Dopant-free, carrier-selective contacts (CSCs) on high efficiency silicon solar cells combine ease of deposition with potential optical benefits. Electron-selective titanium dioxide (TiO) contacts, one of the most promising dopant-free CSC technologies, have been successfully implemented into silicon solar cells with an efficiency over 21%. Here, we report further progress of TiO contacts for silicon solar cells and present an assessment of their industrial feasibility. With improved TiO contact quality and cell processing, a remarkable efficiency of 22.1% has been achieved using an n-type silicon solar cell featuring a full-area TiO contact. Next, we demonstrate the compatibility of TiO contacts with an industrial contact-firing process, its low performance sensitivity to the wafer resistivity, its applicability to ultrathin substrates as well as its long-term stability. Our findings underscore the great appeal of TiO contacts for industrial implementation with their combination of high efficiency with robust fabrication at low cost.

  13. Ion implantation into amorphous Si layers to form carrier-selective contacts for Si solar cells

    International Nuclear Information System (INIS)

    Feldmann, Frank; Mueller, Ralph; Reichel, Christian; Hermle, Martin

    2014-01-01

    This paper reports our findings on the boron and phosphorus doping of very thin amorphous silicon layers by low energy ion implantation. These doped layers are implemented into a so-called tunnel oxide passivated contact structure for Si solar cells. They act as carrier-selective contacts and, thereby, lead to a significant reduction of the cell's recombination current. In this paper we address the influence of ion energy and ion dose in conjunction with the obligatory high-temperature anneal needed for the realization of the passivation quality of the carrier-selective contacts. The good results on the phosphorus-doped (implied V oc = 725 mV) and boron-doped passivated contacts (iV oc = 694 mV) open a promising route to a simplified interdigitated back contact (IBC) solar cell featuring passivated contacts. (copyright 2014 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  14. Wavelet and Spectral Analysis of Some Selected Problems in Reactor Diagnostics

    Energy Technology Data Exchange (ETDEWEB)

    Sunde, Carl

    2004-12-01

    Both spectral and wavelet analysis were successfully used in various diagnostic problems involving non-stationary core processes in nuclear power reactors. Three different problems were treated: two-phase flow identification, detector tube impacting and core-barrel vibrations. The first two problems are of non-stationary nature, whereas the last one is not. In the first problem, neutron radiographic and visible light images of four different vertical two-phase flow regimes, bubbly, slug, chum and annular flow, were analysed and classified with a neuro-wavelet algorithm. The algorithm consists of a wavelet part, using the 2-D discrete wavelet transform and of an artificial neural network. It classifies the different flow regimes with up to 99% efficiency. Detector tubes in a Boiling Water Reactor may execute vibrations and may also impact on nearby fuel-assemblies. Signals from in-core neutron detectors in Ringhals-1 were analysed, for detection of impacting, with both a classical spectral method and wavelet-based methods. The wavelet methods include both the discrete and the continuous 1-D wavelet transform. It was found that there is agreement between the different methods as well as with visual inspections made during the outage at the plant. However, the wavelet technique has the advantage that it does not require expert judgement for the interpretation of the analysis. In the last part two analytical calculations of the neutron noise, induced by shell-mode core-barrel vibrations, were carried out. The results are in good agreement with calculations from a numerical simulator. An out-of-phase behaviour between in-core and ex-core positions was found, which is in agreement with earlier measurements from the Pressurised Water Reactor Ringhals-3. The results from these calculations are planned to be used when diagnosing the shell-mode core-barrel vibrations in an operating plant.

  15. Wavelet and Spectral Analysis of Some Selected Problems in Reactor Diagnostics

    International Nuclear Information System (INIS)

    Sunde, Carl

    2004-12-01

    Both spectral and wavelet analysis were successfully used in various diagnostic problems involving non-stationary core processes in nuclear power reactors. Three different problems were treated: two-phase flow identification, detector tube impacting and core-barrel vibrations. The first two problems are of non-stationary nature, whereas the last one is not. In the first problem, neutron radiographic and visible light images of four different vertical two-phase flow regimes, bubbly, slug, chum and annular flow, were analysed and classified with a neuro-wavelet algorithm. The algorithm consists of a wavelet part, using the 2-D discrete wavelet transform and of an artificial neural network. It classifies the different flow regimes with up to 99% efficiency. Detector tubes in a Boiling Water Reactor may execute vibrations and may also impact on nearby fuel-assemblies. Signals from in-core neutron detectors in Ringhals-1 were analysed, for detection of impacting, with both a classical spectral method and wavelet-based methods. The wavelet methods include both the discrete and the continuous 1-D wavelet transform. It was found that there is agreement between the different methods as well as with visual inspections made during the outage at the plant. However, the wavelet technique has the advantage that it does not require expert judgement for the interpretation of the analysis. In the last part two analytical calculations of the neutron noise, induced by shell-mode core-barrel vibrations, were carried out. The results are in good agreement with calculations from a numerical simulator. An out-of-phase behaviour between in-core and ex-core positions was found, which is in agreement with earlier measurements from the Pressurised Water Reactor Ringhals-3. The results from these calculations are planned to be used when diagnosing the shell-mode core-barrel vibrations in an operating plant

  16. An unsupervised technique for optimal feature selection in attribute profiles for spectral-spatial classification of hyperspectral images

    Science.gov (United States)

    Bhardwaj, Kaushal; Patra, Swarnajyoti

    2018-04-01

    Inclusion of spatial information along with spectral features play a significant role in classification of remote sensing images. Attribute profiles have already proved their ability to represent spatial information. In order to incorporate proper spatial information, multiple attributes are required and for each attribute large profiles need to be constructed by varying the filter parameter values within a wide range. Thus, the constructed profiles that represent spectral-spatial information of an hyperspectral image have huge dimension which leads to Hughes phenomenon and increases computational burden. To mitigate these problems, this work presents an unsupervised feature selection technique that selects a subset of filtered image from the constructed high dimensional multi-attribute profile which are sufficiently informative to discriminate well among classes. In this regard the proposed technique exploits genetic algorithms (GAs). The fitness function of GAs are defined in an unsupervised way with the help of mutual information. The effectiveness of the proposed technique is assessed using one-against-all support vector machine classifier. The experiments conducted on three hyperspectral data sets show the robustness of the proposed method in terms of computation time and classification accuracy.

  17. CO-ANALYSIS OF SOLAR MICROWAVE AND HARD X-RAY SPECTRAL EVOLUTIONS. II. IN THREE SOURCES OF A FLARING LOOP

    International Nuclear Information System (INIS)

    Huang Guangli; Li Jianping

    2011-01-01

    Based on the spatially resolvable data of the Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI) and Nobeyama Radio Heliograph (NoRH), co-analysis of solar hard X-ray and microwave spectral evolution is performed in three separate sources located in one looptop (LT) and two footpoints (FPs) of a huge flaring loop in the 2003 October 24 flare. The RHESSI image spectral evolution in 10-100 keV is always fitted by the well-known soft-hard-soft (SHS) pattern in the three sources. When the total energy is divided into four intervals similar to the Yohkoh/Hard X-ray Telescope, i.e., 12.5-32.5 keV, 32.5-52.5 keV, 52.5-72.5 keV, and 72.5-97.5 keV, the SHS pattern in lower energies is converted gradually to the hard-soft-hard (HSH) pattern in higher energies in all three sources. However, the break energy in the LT and the northeast FP (∼32.5 keV) is evidently smaller than that in the southwest FP (∼72.5 keV). Regarding microwave spectral evolution of the NoRH data, the well-known soft-hard-harder pattern appeared in the southwest FP, while the HSH pattern coexisted in the LT and the northeast FP. The different features of the hard X-ray and microwave spectral evolutions in the three sources may be explained by the loop-loop interaction with another huge loop in the LT and with a compact loop in the northeast FP, where the trapping effect is much stronger than that in the southwest FP. The comparison between the LT and FP spectral indices suggests that the radiation mechanism of X-rays may be quite different in different energy intervals and sources. The calculated electron spectral indices from the predicted mechanisms of X-rays gradually become closer to those from the microwave data with increasing X-ray energies.

  18. Global matrix of thermospheric density values for selected solar/geomagnetic conditions and spacecraft orbital attitudes

    Science.gov (United States)

    Johnson, D. L.

    1984-01-01

    Presented are selected thermospheric/exospheric global mean and extreme density values computed between 130 and 1100 km altitude. These values were generated from the MSFC/J70 reference orbital atmospheric model using different input conditions of solar flux and geomagnetic index, ranging from low to peak. Typical magnitudes of day-night density changes are presented, as an example, for use in space vehicle orbital analyses.

  19. Spectral calibration of filters and detectors of solar EUV telescope for 13.2 nm for the TESIS experiment

    International Nuclear Information System (INIS)

    Kuzin, S.V.; Shestov, S.V.; Pertsov, A.A.; Reva, A.A.; Zuev, S.Yu.; Lopatin, A.Ya.; Luchin, V.I.; Zhou, Kh.; Khuo, T.

    2008-01-01

    The full-sun EUV telescope for 13.2 nm spectral band for the TESIS experiment is designed to produce images of hot coronal plasma (T ∼ 10 MK). Calibration process of optical elements is presented. Spectral transmission of multilayer Zr/Si filters, sensitivity and radiation tolerance of CCD detector have been measured. Peak transmission of EUV filters in working, spectral band reaches 40-50% (filters with 50 and 55 layers are used), spectral dependence of transmission is close to calculated one. Transmission of filters in white light is equal to (1-2)x10 -6 . Sensitivity of CCD ranges from 0.01 to 0.1 ADC units per photon, radiation tolerance is better than 10 9 rad [ru

  20. Spectrally Selective Mirrors with Combined Optical and Thermal Benefit for Photovoltaic Module Thermal Management

    Energy Technology Data Exchange (ETDEWEB)

    Slauch, Ian M. [Department of Chemical Engineering and Materials Science, University of Minnesota, 421 Washington Avenue SE, Minneapolis, Minnesota 55455, United States; Deceglie, Michael G. [National Renewable Energy Laboratory, Golden, Colorado, United States; Silverman, Timothy J. [National Renewable Energy Laboratory, Golden, Colorado, United States; Ferry, Vivian E. [Department of Chemical Engineering and Materials Science, University of Minnesota, 421 Washington Avenue SE, Minneapolis, Minnesota 55455, United States

    2018-03-13

    Waste heat generated during daytime operation of a solar module will raise its temperature and reduce cell efficiency. In addition to thermalization and carrier recombination, one major source of excess heat in modules is the parasitic absorption of light with sub-bandgap energy. Parasitic absorption can be prevented if sub-bandgap radiation is reflected away from the module. We report on the design considerations and projected changes to module energy yield for photonic reflectors capable of reflecting a portion of sub-bandgap radiation while maintaining or improving transmission of light with energy greater than the semiconductor bandgap. Using a previously developed, self-consistent opto-electro-thermal finite-element simulation, we calculate the total additional energy generated by a module, including various photonic reflectors, and decompose these benefits into thermal and optical effects. We show that the greatest total energy yield improvement comes from photonic mirrors designed for the outside of the glass, but that mirrors placed between the glass and the encapsulant can have significant thermal benefit. We then show that optimal photonic mirror design requires consideration of all angles of incidence, despite unequal amounts of radiation arriving at each angle. We find that optimized photonic mirrors will be omnidirectional in the sense that they have beneficial performance, regardless of the angle of incidence of radiation. By fulfilling these criteria, photonic mirrors can be used at different geographic locations or different tilt angles than their original optimization conditions with only marginal changes in performance. We show designs that improve energy output in Golden, Colorado by 3.7% over a full year. This work demonstrates the importance of considering real-world irradiance and weather conditions when designing optical structures for solar applications.

  1. Microstructure and spectral selectivity of Pt-AI203 nanocoatings for high temperature applications

    CSIR Research Space (South Africa)

    Nuru, ZY

    2011-07-01

    Full Text Available Monodispersed spherical core-shell particles of Cr/a-Cr2O3 cermet ACG coatings investigated within this contribution could be successfully employed in thermal converters. Their selectivity depends on their chemical, physical and structural...

  2. Solar building

    OpenAIRE

    Zhang, Luxin

    2014-01-01

    In my thesis I describe the utilization of solar energy and solar energy with building integration. In introduction it is also mentioned how the solar building works, trying to make more people understand and accept the solar building. The thesis introduces different types of solar heat collectors. I compared the difference two operation modes of solar water heating system and created examples of solar water system selection. I also introduced other solar building applications. It is conv...

  3. Enhancement of Handwritings on Selected Charred Documents using Video Spectral Comparator (VSC

    Directory of Open Access Journals (Sweden)

    T. Nataraja Moorthy

    2016-12-01

    Full Text Available Questioned documents are documents whose authenticity is disputed. Documents are destroyed by fires and other means to conceal criminal activities. Charred or burnt documents are a type of questioned document that are likely to contain vital information. These documents are mainly linked to ransoms, forgery, fraud, suicide and other white collar offences. This study aimed to evaluate the ability of a Video Spectral Comparator (VSC-6000 for the enhancement of writings on charred documents and to determine the effectiveness of flood light and white spot beam in VSC on charred documents. A passage was written by different types of writing instruments on different types of writing paper available in Malaysia. Then the handwritten documents were burned until the writings became invisible. The charred documents were viewed under flood light and the white beam by adjusting the wavelengths. Results showed that the writings on the charred document exhibited appreciable enhancement suitable for forensic investigation. The writings were comparatively more visible under the white spot beam than the flood light beam. These findings were recorded through photography. The present study provides a promising method and an effective alternative way to enhance writings on charred documents.

  4. Non-tinted Transparent Luminescent Solar Concentrators Employing Both UV and NIR Selective Absorbers

    Science.gov (United States)

    Zhao, Yimu; Lunt, Richard

    2014-03-01

    Luminescent solar concentrators are a potentially low-cost solar harvesting solution that additionally offer opportunities for integration around buildings and windows. However, the visible absorption and emission of previously demonstrated chromophores hamper their widespread applications including solar windows. Here, we demonstrate non-tinted transparent luminescent solar concentrators (TLSC) that employ both ultraviolet (UV) and near-infrared (NIR) selective absorbing luminophores that create an entirely new paradigm for power-producing transparent surfaces and enhances the potential over UV-only TLSCs. We have previously designed UV-harvesting systems composed of metal halide phosphorescent luminophore blends that enable absorption cutoff positioned at the edge of visible spectrum (430nm) and massive-downconverted emission in the near-infrared (800nm) with quantum yields for luminescence of 75%. Here, we have developed a complimentary TLSC employing fluorescent organic salts with both efficient NIR absorption and deeper NIR emission. We will discuss the photophysical properties of these luminophores, the impact of ligand-host control, and optimization of the TLSC architectures.

  5. Spectroscopic Data of WI, Mo I and Cr I Spectral Lines: Selection ...

    Indian Academy of Sciences (India)

    2016-01-27

    Jan 27, 2016 ... Plasma of electric arc discharges between composite Cu–W, Cu–Mo and Cu–Cr electrodes in argon flow and their spectra were studied by optical emission spectroscopy. Since values of oscillator strengths for W I, Mo I and Cr I presented in various sources are significantly different, selection of ...

  6. Efficiency enhancement of ZnO nanostructure assisted Si solar cell based on fill factor enlargement and UV-blue spectral down-shifting

    Science.gov (United States)

    Gholizadeh, A.; Reyhani, A.; Parvin, P.; Mortazavi, S. Z.

    2017-05-01

    ZnO nanostructures (including nano-plates and nano-rods (NRs)) are grown in various temperatures and Ar/O2 flow rates using thermal chemical vapor deposition, which affect the structure, nano-plate/NR population, and the quality of ZnO nanostructures. X-ray diffraction (XRD) attests that the peak intensity of the crystallographic plane (1 0 0) is correlated to nano-plate abundance. Moreover, optical properties elucidate that the population of nano-plates in samples strongly affect the band gap, binding energy of the exciton, and UV-visible (UV-vis) absorption and spectral luminescence emissions. In fact, the exciton binding energy reduces from ~100 to 80 meV when the population of nano-plates increases in samples. Photovoltaic characteristics based on the drop-casting on Si solar cells reveals three dominant factors, namely, the equivalent series resistance, decreasing reflectance, and down-shifting, in order to scale up the absolute efficiency by 3%. As a consequence, the oxygen vacancies in ZnO nanostructures give rise to the down-shifting and increase of free-carriers, leading to a reduction in the equivalent series resistance and an enlargement of fill factor. To obtain a larger I sc, reduction of spectral reflectance is essential; however, the down-shifting process is shown to be dominant by lessening the surface electron-hole recombination rate over the UV-blue spectral range.

  7. Short- and long-term variability of spectral solar UV irradiance at Thessaloniki, Greece: effects of changes in aerosols, total ozone and clouds

    Directory of Open Access Journals (Sweden)

    I. Fountoulakis

    2016-03-01

    Full Text Available In this study, we discuss the short- and the long-term variability of spectral UV irradiance at Thessaloniki, Greece, using a long, quality-controlled data set from two Brewer spectrophotometers. Long-term changes in spectral UV irradiance at 307.5, 324 and 350 nm for the period 1994–2014 are presented for different solar zenith angles and discussed in association with changes in total ozone column (TOC, aerosol optical depth (AOD and cloudiness observed in the same period. Positive changes in annual mean anomalies of UV irradiance, ranging from 2 to 6 % per decade, have been detected both for clear- and all-sky conditions. The changes are generally greater for larger solar zenith angles and for shorter wavelengths. For clear-skies, these changes are, in most cases, statistically significant at the 95 % confidence limit. Decreases in the aerosol load and weakening of the attenuation by clouds lead to increases in UV irradiance in the summer, of 7–9 % per decade for 64° solar zenith angle. The increasing TOC in winter counteracts the effect of decreasing AOD for this particular season, leading to small, statistically insignificant, negative long-term changes in irradiance at 307.5 nm. Annual mean UV irradiance levels are increasing from 1994 to 2006 and remain relatively stable thereafter, possibly due to the combined changes in the amount and optical properties of aerosols. However, no statistically significant corresponding turning point has been detected in the long-term changes of AOD. The absence of signatures of changes in AOD in the short-term variability of irradiance in the UV-A may have been caused by changes in the single scattering albedo of aerosols, which may counteract the effects of changes in AOD on irradiance. The anti-correlation between the year-to-year variability of the irradiance at 307.5 nm and TOC is clear and becomes clearer as the AOD decreases.

  8. Refinement in black chrome for use as a solar selective coating

    Science.gov (United States)

    Mcdonald, G. E.

    1974-01-01

    Black chrome is significant as a solar selective coating because the current extensive use of black chrome in the electroplating industry as a durable decorative finish makes black chrome widely available on a commercial scale and potentially low in cost as a solar selective coating. Black-chrome deposits were modified by underplating with dull nickel or by being plated on rough surfaces. Both of these procedures increased the visible absorptance. There was no change in the infrared reflectance for the dull-nickel - black-chrome combination from that reported for the bright-nickel - black-chrome combination. However, the bright-nickel - black-chrome coating plated on rough surfaces indicated a slight decrease in infrared reflectance. As integrated over the solar spectrum for air mass 2, the reflectance of the dull-nickel - black-chrome coating was 0.077, of the bright-nickel - black-chrome coating plated on a 0.75-micron (30-microinch) surface was 0.070, of the bright-nickel - black-chrome coating plated on a 2.5 micron (100-microinch) surface was 0.064. The corresponding values for the bright-nickel - black-chrome coating on a 0.0125-micron (0.5-microinch) surface, two samples of black nickel, and two samples of Nextrel black paint were 0.132, 0.123, 0.133, and 0.033, respectively.

  9. Automatic spectral imaging protocol selection and iterative reconstruction in abdominal CT with reduced contrast agent dose: initial experience

    Energy Technology Data Exchange (ETDEWEB)

    Lv, Peijie; Liu, Jie; Chai, Yaru; Yan, Xiaopeng; Gao, Jianbo; Dong, Junqiang [The First Affiliated Hospital of Zhengzhou University, Department of Radiology, Zhengzhou, Henan Province (China)

    2017-01-15

    To evaluate the feasibility, image quality, and radiation dose of automatic spectral imaging protocol selection (ASIS) and adaptive statistical iterative reconstruction (ASIR) with reduced contrast agent dose in abdominal multiphase CT. One hundred and sixty patients were randomly divided into two scan protocols (n = 80) each; protocol A, 120 kVp/450 mgI/kg, filtered back projection algorithm (FBP); protocol B, spectral CT imaging with ASIS and 40 to 70 keV monochromatic images generated per 300 mgI/kg, ASIR algorithm. Quantitative parameters (image noise and contrast-to-noise ratios [CNRs]) and qualitative visual parameters (image noise, small structures, organ enhancement, and overall image quality) were compared. Monochromatic images at 50 keV and 60 keV provided similar or lower image noise, but higher contrast and overall image quality as compared with 120-kVp images. Despite the higher image noise, 40-keV images showed similar overall image quality compared to 120-kVp images. Radiation dose did not differ between the two protocols, while contrast agent dose in protocol B was reduced by 33 %. Application of ASIR and ASIS to monochromatic imaging from 40 to 60 keV allowed contrast agent dose reduction with adequate image quality and without increasing radiation dose compared to 120 kVp with FBP. (orig.)

  10. GaAs Solar Cells on V-Grooved Silicon via Selective Area Growth: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Warren, Emily L [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Jain, Nikhil [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Tamboli, Adele C [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Vaisman, Michelle [Yale University; Li, Qiang [Hong Kong University of Science and Technology; Lau, Kei May [Hong Kong University of Science and Technology

    2017-08-31

    Interest in integrating III-Vs onto Si has recently resurged as a promising pathway towards high-efficiency, low-cost tandem photovoltaics. Here, we present a single junction GaAs solar cell grown monolithically on polished Si (001) substrates using V-grooves, selective area growth, and aspect ratio trapping to mitigate defect formation without the use of expensive, thick graded buffers. The GaAs is free of antiphase domains and maintains a relatively low TDD of 4x107 cm-2, despite the lack of a graded buffer. This 6.25 percent-efficient demonstration solar cell shows promise for further improvements to III-V/Si tandems to enable cost-competitive photovoltaics.

  11. Stepped Fault Line Selection Method Based on Spectral Kurtosis and Relative Energy Entropy of Small Current to Ground System

    Directory of Open Access Journals (Sweden)

    Xiaowei Wang

    2014-01-01

    Full Text Available This paper proposes a stepped selection method based on spectral kurtosis relative energy entropy. Firstly, the length and type of window function are set; then when fault occurs, enter step 1: the polarity of first half-wave extremes is analyzed; if the ratios of extremes between neighboring lines are positive, the bus bar is the fault line, else, the SK relative energy entropies are calculated, and then enter step 2: if the obtained entropy multiple is bigger than the threshold or equal to the threshold, the overhead line of max entropy corresponding is the fault line, if not, enter step 3: the line of max entropy corresponding is the fault line. At last, the applicability of the proposed algorithm is presented, and the comparison results are discussed.

  12. Controlling adverse and beneficial effects of solar UV radiation by wearing suitable clothes - spectral transmission of different kinds of fabrics.

    Science.gov (United States)

    Sobolewski, Piotr S; Krzyścin, Janusz W; Jarosławski, Janusz; Wink, Jakub; Lesiak, Aleksandra; Narbutt, Joanna

    2014-11-01

    Humans should avoid prolonged exposure to the Sun during the warm subperiod of the year with naturally high solar UV level. One of the known recommendations to avoid excessive UV radiation is wearing clothes with UV protection additives. However there is an important question: how do we get an adequate solar UV radiation, which maintains a healthy status of vitamin D, without facing overexposure risks? It is found that some kind of 100% cotton knitted fabric, used in the production of normal daily clothing, has ∼15% transmittance of solar UV. Model studies show that a garment made of this fabric allows larger synthesis of vitamin D3 in human body without the erythema risks (skin redness). Thus the adequate level of vitamin D could be attained safely by a person exposing only small part of the body (face, palms) during the period (May-August) of the year. Copyright © 2014 Elsevier B.V. All rights reserved.

  13. [Characteristic wavelengths selection of soluble solids content of pear based on NIR spectral and LS-SVM].

    Science.gov (United States)

    Fan, Shu-xiang; Huang, Wen-qian; Li, Jiang-bo; Zhao, Chun-jiang; Zhang, Bao-hua

    2014-08-01

    To improve the precision and robustness of the NIR model of the soluble solid content (SSC) on pear. The total number of 160 pears was for the calibration (n=120) and prediction (n=40). Different spectral pretreatment methods, including standard normal variate (SNV) and multiplicative scatter correction (MSC) were used before further analysis. A combination of genetic algorithm (GA) and successive projections algorithm (SPA) was proposed to select most effective wavelengths after uninformative variable elimination (UVE) from original spectra, SNV pretreated spectra and MSC pretreated spectra respectively. The selected variables were used as the inputs of least squares-support vector machine (LS-SVM) model to build models for de- termining the SSC of pear. The results indicated that LS-SVM model built using SNVE-UVE-GA-SPA on 30 characteristic wavelengths selected from full-spectrum which had 3112 wavelengths achieved the optimal performance. The correlation coefficient (Rp) and root mean square error of prediction (RMSEP) for prediction sets were 0.956, 0.271 for SSC. The model is reliable and the predicted result is effective. The method can meet the requirement of quick measuring SSC of pear and might be important for the development of portable instruments and online monitoring.

  14. Thermal and optical analysis of selective absorber coatings based on soot for applications in solar cookers

    Science.gov (United States)

    Servín, H.; Peña, M.; Sobral, H.; González, M.

    2017-01-01

    The thermal and optical properties of selective absorber coatings of a solar cooker have been investigated. Coatings have been prepared using soot from pine resin, wood stove and sugarcane, previously separated by size. Results show that the cooking power and the overall efficiency of these pots are higher than others painted with black primer. Besides, by using an integrating sphere, the diffuse reflectance of absorbers has been obtained. Lower values of the reflectance have been measured for the pots covered with soot, showing a high correlation with the results achieved from the thermal tests, considering the measurement errors.

  15. Selections of the metric projection operator and strict solarity of sets with continuous metric projection

    Science.gov (United States)

    Alimov, A. R.

    2017-07-01

    In a broad class of finite-dimensional Banach spaces, we show that a closed set with lower semicontinuous metric projection is a strict sun, admits a continuous selection of the metric projection operator onto it, has contractible intersections with balls, and its (nonempty) intersection with any closed ball is a retract of this ball. For sets with continuous metric projection, a number of new results relating the solarity of such sets to the stability of the operator of best approximation are obtained. Bibliography 25 titles.

  16. InterTechnology Corporation report of solar energy systems installation costs for selected commercial buildings

    Energy Technology Data Exchange (ETDEWEB)

    None

    1976-12-01

    The results of a study in which the primary objective was to determine actual costs associated with the installation of solar collector and thermal energy storage subsystems in specific non-residential building applications are presented. A secondary objective of the study was to assemble details of existing solar collector and storage subsystem installations, including caveats concerning cost estimating, logistics and installation practices. The study began with the development of an exhaustive listing and compilation of basic data and contacts for non-residential applications of solar heating and cooling of buildings. Both existing projects and those under construction were surveyed. Survey summary sheets for each project encountered are provided as a separate appendix. Subsequently, the rationale used to select the projects studied in-depth is presented. The results of each of the detailed studies are then provided along with survey summary sheets for each of the projects studied. Installation cost data are summarized and the significance of the differences and similarities between the reported projects is discussed. After evaluating the data obtained from the detailed studies, methods for reducing installation labor costs are postulated based on the experience of the study. Some of the methods include modularization of collectors, preplumbing and preinsulating, and collector placement procedures. Methods of cost reduction and a summary discussion of prominent problems encountered in the projects are considered.(WHK)

  17. Efficient Regular Perovskite Solar Cells Based on Pristine [70]Fullerene as Electron-Selective Contact.

    Science.gov (United States)

    Collavini, Silvia; Kosta, Ivet; Völker, Sebastian F; Cabanero, German; Grande, Hans J; Tena-Zaera, Ramón; Delgado, Juan Luis

    2016-06-08

    [70]Fullerene is presented as an efficient alternative electron-selective contact (ESC) for regular-architecture perovskite solar cells (PSCs). A smart and simple, well-described solution processing protocol for the preparation of [70]- and [60]fullerene-based solar cells, namely the fullerene saturation approach (FSA), allowed us to obtain similar power conversion efficiencies for both fullerene materials (i.e., 10.4 and 11.4 % for [70]- and [60]fullerene-based devices, respectively). Importantly, despite the low electron mobility and significant visible-light absorption of [70]fullerene, the presented protocol allows the employment of [70]fullerene as an efficient ESC. The [70]fullerene film thickness and its solubility in the perovskite processing solutions are crucial parameters, which can be controlled by the use of this simple solution processing protocol. The damage to the [70]fullerene film through dissolution during the perovskite deposition is avoided through the saturation of the perovskite processing solution with [70]fullerene. Additionally, this fullerene-saturation strategy improves the performance of the perovskite film significantly and enhances the power conversion efficiency of solar cells based on different ESCs (i.e., [60]fullerene, [70]fullerene, and TiO2 ). Therefore, this universal solution processing protocol widens the opportunities for the further development of PSCs. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. Solar Spectral and Module Temperature Influence on the Outdoor Performance of Thin Film PV Modules Deployed on a Sunny Inland Site

    Directory of Open Access Journals (Sweden)

    G. Nofuentes

    2013-01-01

    Full Text Available This work aims at analysing the influence of both module temperature and solar spectrum distribution on the outdoor performance of the following thin film technologies: hydrogenated amorphous silicon (a-Si:H, cadmium telluride (CdTe, copper indium gallium selenide sulfide (CIGS, and hydrogenated amorphous silicon/hydrogenated microcrystalline silicon hetero-junction (a-Si:H/μc-Si:H. A 12-month experimental campaign carried out in a sunny inland site in which a module of each one of these technologies was tested and measured outdoors has provided the necessary empirical data. Results show that module temperature exerts a limited influence on the performance of the tested a-Si:H, CdTe, and a-Si:H/μc-Si:H modules. In contrast, the outdoor behaviour of the CIGS module is the most affected by its temperature. Blue-rich spectra enhance the outdoor behaviour of the a-Si:H and a-Si:H/μc-Si:H modules while it is the other way round for the CIGS module. However, the CdTe specimen shows little sensitivity to the solar spectrum distribution. Anyway, spectral effects are scarcely relevant on an annual basis, ranging from gains for the CIGS module (1.5% to losses for the a-Si:H module (1.0%. However, the seasonal impact of the spectrum shape is more noticeable in these two materials; indeed, spectral issues may cause performance gains or losses of up to some 4% when winter and summer periods are considered.

  19. Modeling solar oscillation power spectra. II. Parametric model of spectral lines observed in Doppler-velocity measurements

    International Nuclear Information System (INIS)

    Vorontsov, Sergei V.; Jefferies, Stuart M.

    2013-01-01

    We describe a global parametric model for the observed power spectra of solar oscillations of intermediate and low degree. A physically motivated parameterization is used as a substitute for a direct description of mode excitation and damping as these mechanisms remain poorly understood. The model is targeted at the accurate fitting of power spectra coming from Doppler-velocity measurements and uses an adaptive response function that accounts for both the vertical and horizontal components of the velocity field on the solar surface and for possible instrumental and observational distortions. The model is continuous in frequency, can easily be adapted to intensity measurements, and extends naturally to the analysis of high-frequency pseudomodes (interference peaks at frequencies above the atmospheric acoustic cutoff).

  20. Modeling solar oscillation power spectra. II. Parametric model of spectral lines observed in Doppler-velocity measurements

    Energy Technology Data Exchange (ETDEWEB)

    Vorontsov, Sergei V. [Astronomy Unit, School of Physics and Astronomy, Queen Mary University of London, Mile End Road, London E1 4NS (United Kingdom); Jefferies, Stuart M., E-mail: S.V.Vorontsov@qmul.ac.uk, E-mail: stuartj@ifa.hawaii.edu [Institute for Astronomy, University of Hawaii, 34 Ohia Ku Street, Pukalani, HI 96768 (United States)

    2013-11-20

    We describe a global parametric model for the observed power spectra of solar oscillations of intermediate and low degree. A physically motivated parameterization is used as a substitute for a direct description of mode excitation and damping as these mechanisms remain poorly understood. The model is targeted at the accurate fitting of power spectra coming from Doppler-velocity measurements and uses an adaptive response function that accounts for both the vertical and horizontal components of the velocity field on the solar surface and for possible instrumental and observational distortions. The model is continuous in frequency, can easily be adapted to intensity measurements, and extends naturally to the analysis of high-frequency pseudomodes (interference peaks at frequencies above the atmospheric acoustic cutoff).

  1. Material Selection for Dye Sensitized Solar Cells Using Multiple Attribute Decision Making Approach

    Directory of Open Access Journals (Sweden)

    Sarita Baghel

    2014-01-01

    Full Text Available Dye sensitized solar cells (DSCs provide a potential alternative to conventional p-n junction photovoltaic devices. The semiconductor thin film plays a crucial role in the working of DSC. This paper aims at formulating a process for the selection of optimum semiconductor material for nanostructured thin film using multiple attribute decision making (MADM approach. Various possible available semiconducting materials and their properties like band gap, cost, mobility, rate of electron injection, and static dielectric constant are considered and MADM technique is applied to select the best suited material. It was found that, out of all possible candidates, titanium dioxide (TiO2 is the best semiconductor material for application in DSC. It was observed that the proposed results are in good agreement with the experimental findings.

  2. On the use of photothermal techniques for the characterization of solar-selective coatings

    Science.gov (United States)

    Ramírez-Rincón, J. A.; Ares-Muzio, O.; Macias, J. D.; Estrella-Gutiérrez, M. A.; Lizama-Tzec, F. I.; Oskam, G.; Alvarado-Gil, J. J.

    2018-03-01

    The efficiency of the conversion of solar energy into thermal energy is determined by the optical and thermal properties of the selective coating, in particular, the solar absorptance and thermal emittance at the desired temperature of the specific application. Photothermal techniques are the most appropriate methods to explore these properties, however, a quantitative determination using photothermal radiometry, which is based on the measurement of emitted radiation caused by the heating generated by a modulated light source, has proven to be elusive. In this work, we present experimental results for selective coatings based on electrodeposited black nickel-nickel on both stainless steel and copper substrates, as well as for commercial TiNOX coatings on aluminum, illustrating that the radiation emitted by the surface depends on the optical absorption, thermal emissivity and on the light-into-heat energy conversion efficiency (quantum efficiency). We show that a combination of photothermal radiometry and photoacoustic spectroscopy can successfully account for these parameters, and provide values for the emissivity in agreement with values obtained by Fourier-transform infrared spectroscopy.

  3. Magnetic fields in proton solar flare of X17.2/4B class according to data of simultaneous measurements in a few spectral lines

    Science.gov (United States)

    Lozitsky, V.; Lozitska, N.

    2017-06-01

    Spectral-polarized magnetic field measurements in solar flare of 28 October 2003 of X17.2/4B class are compared in six FeI lines and in Hα line. Observations were carried out on Echelle spectrograph of horizontal solar telescope of Astronomical Observatory of Taras Shevchenko National University of Kyiv. Presented data relate to peak phase of flare and a place of photosphere outside sunspots where effective (average) magnetic field in FeI 6302.5 line was about 100 G and had S polarity. Measured splitting of emissive peaks in cores of strong FeI lines of 15th multiplet correspond to stronger fields, in range 550-700 G and S polarity too. Noticeablre splitting of emissive peaks (11-20 mÅ) were found also in Fe I 5434.527 line with effective Lande factor geff = -0.014. Value of this splitting and its sign indicate the existence of extremely strong fields of 25-50 kG of opposite (N) polarity which had negative Doppler velocities (lifting of plasma) on level of 1.7-2.2 km/sec. Magnetic field according to Hα line was 300 G and N polarity. Presented results indicate the essential inhomogeneity of magnetic field in flare volume which include the opposite polarities along the line of sight and wide range of effective magnetic fields.

  4. Solar holography

    Science.gov (United States)

    Ludman, Jacques E.; Riccobono, Juanita R.; Caulfield, H. John; Upton, Timothy D.

    2002-07-01

    A solar photovoltaic energy collection system using a reflection hologram is described herein. The system uses a single-axis tracking system in conjunction with a spectral- splitting holographic element. The hologram accurately focuses the desired regions of the solar spectrum to match the bandgaps of two ro more different solar cells, while diverting unused IR wavelengths away. Other applications for solar holography include daylighting and greenhouses.

  5. The Einstein@Home Gamma-ray Pulsar Survey. II. Source Selection, Spectral Analysis, and Multiwavelength Follow-up

    Science.gov (United States)

    Wu, J.; Clark, C. J.; Pletsch, H. J.; Guillemot, L.; Johnson, T. J.; Torne, P.; Champion, D. J.; Deneva, J.; Ray, P. S.; Salvetti, D.; Kramer, M.; Aulbert, C.; Beer, C.; Bhattacharyya, B.; Bock, O.; Camilo, F.; Cognard, I.; Cuéllar, A.; Eggenstein, H. B.; Fehrmann, H.; Ferrara, E. C.; Kerr, M.; Machenschalk, B.; Ransom, S. M.; Sanpa-Arsa, S.; Wood, K.

    2018-02-01

    We report on the analysis of 13 gamma-ray pulsars discovered in the Einstein@Home blind search survey using Fermi Large Area Telescope (LAT) Pass 8 data. The 13 new gamma-ray pulsars were discovered by searching 118 unassociated LAT sources from the third LAT source catalog (3FGL), selected using the Gaussian Mixture Model machine-learning algorithm on the basis of their gamma-ray emission properties being suggestive of pulsar magnetospheric emission. The new gamma-ray pulsars have pulse profiles and spectral properties similar to those of previously detected young gamma-ray pulsars. Follow-up radio observations have revealed faint radio pulsations from two of the newly discovered pulsars and enabled us to derive upper limits on the radio emission from the others, demonstrating that they are likely radio-quiet gamma-ray pulsars. We also present results from modeling the gamma-ray pulse profiles and radio profiles, if available, using different geometric emission models of pulsars. The high discovery rate of this survey, despite the increasing difficulty of blind pulsar searches in gamma rays, suggests that new systematic surveys such as presented in this article should be continued when new LAT source catalogs become available.

  6. SNR and BER Models and the Simulation for BER Performance of Selected Spectral Amplitude Codes for OCDMA

    Directory of Open Access Journals (Sweden)

    Abdul Latif Memon

    2014-01-01

    Full Text Available Many encoding schemes are used in OCDMA (Optical Code Division Multiple Access Network but SAC (Spectral Amplitude Codes is widely used. It is considered an effective arrangement to eliminate dominant noise called MAI (Multi Access Interference. Various codes are studied for evaluation with respect to their performance against three noises namely shot noise, thermal noise and PIIN (Phase Induced Intensity Noise. Various Mathematical models for SNR (Signal to Noise Ratios and BER (Bit Error Rates are discussed where the SNRs are calculated and BERs are computed using Gaussian distribution assumption. After analyzing the results mathematically, it is concluded that ZCC (Zero Cross Correlation Code performs better than the other selected SAC codes and can serve larger number of active users than the other codes do. At various receiver power levels, analysis points out that RDC (Random Diagonal Code also performs better than the other codes. For the power interval between -10 and -20 dBm performance of RDC is better ZCC. Their lowest BER values suggest that these codes should be part of an efficient and cost effective OCDM access network in the future.

  7. Performance Improvements of Selective Emitters by Laser Openings on Large-Area Multicrystalline Si Solar Cells

    Directory of Open Access Journals (Sweden)

    Sheng-Shih Wang

    2014-01-01

    Full Text Available This study focuses on the laser opening technique used to form a selective emitter (SE structure on multicrystalline silicon (mc-Si. This technique can be used in the large-area (156 × 156 mm2 solar cells. SE process of this investigation was performed using 3 samples SE1–SE3. Laser fluences can vary in range of 2–5 J/cm2. The optimal conversion efficiency of 15.95% is obtained with the SE3 (2 J/cm2 fluence after laser opening with optimization of heavy and light dopant, which yields a gain of 0.48%abs compared with that of a reference cell (without fluence. In addition, this optimal SE3 cell displays improved characteristics compared with other cells with a higher average value of external quantum efficiency (EQEavg = 68.6% and a lower average value of power loss (Ploss = 2.33 mW/cm2. For the fabrication of solar cells, the laser opening process comprises fewer steps than traditional photolithography does. Furthermore, the laser opening process decreases consumption of chemical materials; therefore, the laser opening process decreases both time and cost. Therefore, SE process is simple, cheap, and suitable for commercialization. Moreover, the prominent features of the process render it effective means to promote overall performance in the photovoltaic industry.

  8. Solution-processed molybdenum oxide for hole-selective contacts on crystalline silicon solar cells

    Science.gov (United States)

    Tong, Jingnan; Wan, Yimao; Cui, Jie; Lim, Sean; Song, Ning; Lennon, Alison

    2017-11-01

    Sub-stoichiometric molybdenum oxide (MoOx) films are commonly deposited on crystalline silicon (c-Si) solar cells by thermal evaporation, a process that requires high vacuum and provides limited control of oxide stoichiometry and in consequence limited control of hole transport properties. Here, we report on a method of forming MoOx films on crystalline silicon wafer surfaces by spin-coating hydrogen molybdenum bronze solutions. It is shown that a ∼2.8 nm thick interfacial SiOx layer forms under the spin-coated MoOx films and that the as-deposited MoOx is amorphous and sub-stoichiometric (x = 2.73), with the concentration of oxygen vacancies in the MoOx being able to be reduced by annealing in air. The as-deposited MoOx films show comparable contact resistivity and passivation quality on c-Si wafers to thermally-evaporated MoOx, demonstrating their potential to be an effective hole-selective contact layer for c-Si solar cells and an alternative for thermally-evaporated films.

  9. Comparison of the solar spectral ultraviolet irradiance in motor vehicles with windows in an open and closed position

    Science.gov (United States)

    Kimlin, M. G.; Parisi, A. V.; Carter, B. D.; Turnbull, D.

    2002-06-01

    The solar ultraviolet (UV) spectrum was measured by a spectroradiometer located inside two common Australian vehicles: a family wagon and a four-wheel-drive vehicle. The entrance optics of the spectroradiometer was orientated, in turn, on a horizontal plane, towards the driver and passenger windows and towards the windshield. UV spectra were recorded when the vehicles' windows were in an open and closed position. For a typical Australian family wagon, on a horizontal plane inside the vehicle, closing the windows decreased, the total UV irradiance by a factor of 3.2, whilst in a four-wheel drive the irradiance decreased by a factor of 2.1. In order to reduce the likelihood of developing of UV-related eye and skin disorders, drivers should use appropriate UV protection whilst driving a vehicle with the windows in an open position. Results gained from this research provide new findings on the exposure of humans to UV in a vehicle.

  10. Enhancing the Durability and Carrier Selectivity of Perovskite Solar Cells Using a Blend Interlayer.

    Science.gov (United States)

    Sin, Dong Hun; Jo, Sae Byeok; Lee, Seung Goo; Ko, Hyomin; Kim, Min; Lee, Hansol; Cho, Kilwon

    2017-05-31

    A mechanically and thermally stable and electron-selective ZnO/CH 3 NH 3 PbI 3 interface is created via hybridization of a polar insulating polymer, poly(ethylene glycol) (PEG), into ZnO nanoparticles (NPs). PEG successfully passivates the oxygen defects on ZnO and prevents direct contact between CH 3 NH 3 PbI 3 and defects on ZnO. A uniform CH 3 NH 3 PbI 3 film is formed on a soft ZnO:PEG layer after dispersion of the residual stress from the volume expansion during CH 3 NH 3 PbI 3 conversion. PEG also increases the work of adhesion of the CH 3 NH 3 PbI 3 film on the ZnO:PEG layer and holds the CH 3 NH 3 PbI 3 film with hydrogen bonding. Furthermore, PEG tailors the interfacial electronic structure of ZnO, reducing the electron affinity of ZnO. As a result, a selective electron-collection cathode is formed with a reduced electron affinity and a deep-lying valence band of ZnO, which significantly enhances the carrier lifetime (473 μs) and photovoltaic performance (15.5%). The mechanically and electrically durable ZnO:PEG/CH 3 NH 3 PbI 3 interface maintains the sustainable performance of the solar cells over 1 year. A soft and durable cathodic interface via PEG hybridization in a ZnO layer is an effective strategy toward flexible electronics and commercialization of the perovskite solar cells.

  11. Profiles of spectral lines, magnetic fields and thermodynamical conditions in the X17.2/4B solar flare of October 28, 2003

    Science.gov (United States)

    Lozitsky, V. G.; Baranovsky, E. A.; Lozitska, N. I.; Tarashchuk, V. P.

    2018-03-01

    We analyse the peak phase of the exclusively powerful solar proton flare of October 28, 2003 which had originated in the active region NOAA 0486. For studying the physical conditions in the flare, we used twelve spectral lines including lines from FeI, FeII, and the Hα, Hβ, Hγ, Hδ lines observed with the Echelle spectrograph of the horizontal solar telescope of the Astronomical Observatory of the Taras Shevchenko National University of Kyiv. We found that this flare had a unique Balmer decrement, with the record ratio I (Hβ) / I(Hα) = 1.68 of Hβ and Hα intensities, which is unprecedented for all flares observed. In a place outside sunspots, the effective magnetic field measured by splitting `center of gravity' I ± V profiles was found within the range of 0-200 G in the middle photosphere, till 1200 G in the upper photosphere and the temperature minimum zone and up to 500 G in the chromosphere. The essential broadening of the FeI 5250.2 line versus the FeI 5247.1 one was found indicating the presence of a strong (800-1100 G) `turbulent' field in the middle photosphere. A semi-empirical model of the chromosphere constructed using the algorithms in PANDORA code has an interesting peculiarity, namely, three discrete layers with an increased concentration and / or temperature, including a very dense and thin layer with the following parameters: the concentration of hydrogen nH = 1018 cm3, the thickness Δh = 3-5 km, and a height of h ≈ 1200 km above the photosphere.

  12. Radical-Scavenging Activity of a Sunscreen Enriched by Antioxidants Providing Protection in the Whole Solar Spectral Range.

    Science.gov (United States)

    Souza, Carla; Maia Campos, Patrícia; Schanzer, Sabine; Albrecht, Stephanie; Lohan, Silke B; Lademann, Jürgen; Darvin, Maxim E; Meinke, Martina C

    2017-01-01

    The main reason for extrinsic skin aging is the negative action of free radicals. The formation of free radicals in the skin has been associated with ultraviolet (UV) exposure and also to visible (VIS) and near-infrared (NIR) irradiations. The aim of the present study was to evaluate the efficacy of a sunscreen in the whole solar range. The radical-scavenging activity of a sunscreen in the UV, VIS, and NIR ranges was evaluated using electron paramagnetic resonance spectroscopy. Ex vivo penetration profiles were determined using confocal Raman microscopy on porcine ear skin at different time points after application. Compared to the untreated skin, the sunscreen decreased the skin radical formation in the UV and VIS regions. Additional protection in the VIS and NIR ranges was observed for the sunscreen containing antioxidants (AO). The penetration depth of the cream was less than 11.2 ± 3.0 µm for all time points. A sunscreen containing AO improved the photoprotection in the VIS and NIR ranges. The sunscreen was retained in the stratum corneum. Therefore, these results show the possibility of the development of effective and safer sunscreen products. © 2017 S. Karger AG, Basel.

  13. Fabrication and characterisation of selective solar absorber surfaces prepared by sol-gel technique

    CSIR Research Space (South Africa)

    Katumba, G

    2006-07-01

    Full Text Available The investigation and development of carbon-silica composites has been going on for some time. Different applications such as adsorbents, biosensors, templates and solar absorbers have emanated from these studies. The concept of using solar...

  14. A comparison of random forest and its Gini importance with standard chemometric methods for the feature selection and classification of spectral data

    Directory of Open Access Journals (Sweden)

    Himmelreich Uwe

    2009-07-01

    Full Text Available Abstract Background Regularized regression methods such as principal component or partial least squares regression perform well in learning tasks on high dimensional spectral data, but cannot explicitly eliminate irrelevant features. The random forest classifier with its associated Gini feature importance, on the other hand, allows for an explicit feature elimination, but may not be optimally adapted to spectral data due to the topology of its constituent classification trees which are based on orthogonal splits in feature space. Results We propose to combine the best of both approaches, and evaluated the joint use of a feature selection based on a recursive feature elimination using the Gini importance of random forests' together with regularized classification methods on spectral data sets from medical diagnostics, chemotaxonomy, biomedical analytics, food science, and synthetically modified spectral data. Here, a feature selection using the Gini feature importance with a regularized classification by discriminant partial least squares regression performed as well as or better than a filtering according to different univariate statistical tests, or using regression coefficients in a backward feature elimination. It outperformed the direct application of the random forest classifier, or the direct application of the regularized classifiers on the full set of features. Conclusion The Gini importance of the random forest provided superior means for measuring feature relevance on spectral data, but – on an optimal subset of features – the regularized classifiers might be preferable over the random forest classifier, in spite of their limitation to model linear dependencies only. A feature selection based on Gini importance, however, may precede a regularized linear classification to identify this optimal subset of features, and to earn a double benefit of both dimensionality reduction and the elimination of noise from the classification task.

  15. Resonant tunneling diodes as energy-selective contacts used in hot-carrier solar cells

    International Nuclear Information System (INIS)

    Takeda, Yasuhiko; Sugimoto, Noriaki; Ichiki, Akihisa; Kusano, Yuya; Motohiro, Tomoyoshi

    2015-01-01

    Among the four features unique to hot-carrier solar cells (HC-SCs): (i) carrier thermalization time and (ii) carrier equilibration time in the absorber, (iii) energy-selection width and (iv) conductance of the energy-selective contacts (ESCs), requisites of (i)-(iii) for high conversion efficiency have been clarified. We have tackled the remaining issues related to (iv) in the present study. The detailed balance model of HC-SC operation has been improved to involve a finite value of the ESC conductance to find the required values, which in turn has been revealed to be feasible using resonant tunneling diodes (RTDs) consisting of semiconductor quantum dots (QDs) and quantum wells (QWs) by means of a formulation to calculate the conductance of the QD- and QW-RTDs derived using the rigorous solutions of the effective-mass Hamiltonians. Thus, all of the four requisites unique to HC-SCs to achieve high conversion efficiency have been elucidated, and the two requisites related to the ESCs can be fulfilled using the QD- and QW-RTDs

  16. IAU 2015 Resolution B3 on Recommended Nominal Conversion Constants for Selected Solar and Planetary Properties

    DEFF Research Database (Denmark)

    Mamajek, E. E.; Prsa, A.; Torres, G.

    2015-01-01

    Assembly in Honolulu. IAU 2015 Resolution B3 adopts a set of nominal solar, terrestrial, and jovian conversion constants for stellar and (exo)planetary astronomy which are defined to be exact SI values. While the nominal constants are based on current best estimates (CBEs; which have uncertainties......, are not secularly constant, and are updated regularly using new observations), they should be interpreted as standard values and not as CBEs. IAU 2015 Resolution B3 adopts five solar conversion constants (nominal solar radius, nominal total solar irradiance, nominal solar luminosity, nominal solar effective...... temperature, and nominal solar mass parameter) and six planetary conversion constants (nominal terrestrial equatorial radius, nominal terrestrial polar radius, nominal jovian equatorial radius, nominal jovian polar radius, nominal terrestrial mass parameter, and nominal jovian mass parameter)....

  17. Socio-technical assessment of solar photovoltaic systems implemented for rural electrification in selected villages of Sundarbans region of India

    Directory of Open Access Journals (Sweden)

    Rashmi Murali

    2015-10-01

    Full Text Available The power situation in rural India continues to remain poor with around one-third of the rural population without access to any form of electricity. The consequence of which is kerosene being used as a major source of lighting for un-electrified households as well as households with intermittent access to electricity in rural areas. While grid based electrification has been the most common approach, decentralized renewable energy options especially, solar PV systems have also been adopted as a cost effective mode of electrification. This paper presents the results of socio-technical assessment of solar photovoltaic interventions namely, solar home systems, solar mini-grid and solar AC pico-grids, which have been used to electrify selected villages in Sundarbans region of India. The study is focused on technical, financial, and institutional aspects along with the social impact assessment of PV based electrification in the Sundarbans region. The results of the study elucidate that, in general, the impacts of the solar PV solutions used for electrification have been largely positive, especially benefits of reduced kerosene consumption, ease in studying and cooking and reduced health effects. The study also finds that technology is not the only factor on which the viability of a program depends, but institutional and financial aspects also play a significant role. The need of the hour is to develop a strong institutional framework and enabling policies for achieving higher success rates in PV programs.

  18. History of Spanish Selection of the International Solar Energy; Historia de la Asociacion Espanola de Energia solar

    Energy Technology Data Exchange (ETDEWEB)

    Vazquez, M.

    2004-07-01

    This paper is about the old and new Spanish Sections of the International Solar Energy Society (ISES). The old Section was formed on the initiative of the Spanish Association Atecyr and was named ISES Espana. As a legal Spanish association, it developed its activities from 1981 until 1991 when economic difficulties made ISES suspend the Section. In that year Prof. Manuel Vazquez, director of the Laboratory of Solar Energy of the University of Vigo, became interested in the subject and participated in his restlessness to other Spanish members of ISES. All of them agreed to create a new Spanish association under the name of Asociacion Espanola de Energia Solar (AEDES), which was registered as an ONG in the Spanish National Register of Associations and ratified by ISES as its Spanish Section in 1993. In this paper the significant data of the old and new sections are given, including the names of representative people and members of the Board and the development of the membership. (Author)

  19. The method of assessment of solar potential for selected area with use Geographical Information Systems

    Directory of Open Access Journals (Sweden)

    Netzel P.

    2012-10-01

    Full Text Available This paper describes a method for analyse the spatial distribution of solar energy potential based on calculated solar irradiation with use of GIS (Geographical Information System. Program GIS GRASS gives opportunity to create spatial distribution of solar radiation which is taking into account such important elements like: terrain, atmosphere, pollutants, water and aerosol in atmosphere, clouds. The use of GIS GRASS module – named r.sun gives opportunity to generate spatial distribution of solar radiation on Lower Silesia (south – west part of Poland. In this work the analyse of solar potential to obtain hot water in the individual household were done. This analyse was based on the amount of total solar radiation monthly sums generated by r.sun module. Spatial distribution of solar potential was used to classify the Lower Silesia region in terms of work efficiency solar installations. It is very usefully because it gives people information about the date of the return of the funds invested in the purchase of the solar collectors.

  20. Perovskite Solar Cells Based on Low-Temperature Processed Indium Oxide Electron Selective Layers.

    Science.gov (United States)

    Qin, Minchao; Ma, Junjie; Ke, Weijun; Qin, Pingli; Lei, Hongwei; Tao, Hong; Zheng, Xiaolu; Xiong, Liangbin; Liu, Qin; Chen, Zhiliang; Lu, Junzheng; Yang, Guang; Fang, Guojia

    2016-04-06

    Indium oxide (In2O3) as a promising n-type semiconductor material has been widely employed in optoelectronic applications. In this work, we applied low-temperature solution-processed In2O3 nanocrystalline film as an electron selective layer (ESL) in perovskite solar cells (PSCs) for the first time. By taking advantages of good optical and electrical properties of In2O3 such as high mobility, wide band gap, and high transmittance, we obtained In2O3-based PSCs with a good efficiency exceeding 13% after optimizing the concentration of the precursor solution and the annealing temperature. Furthermore, to enhance the performance of the In2O3-based PSCs, a phenyl-C61-butyric acid methyl ester (PCBM) layer was introduced to modify the surface of the In2O3 film. The PCBM film could fill up the pinholes or cracks along In2O3 grain boundaries to passivate the defects and make the ESL extremely compact and uniform, which is conducive to suppressing the charge recombination. As a result, the efficiency of the In2O3-based PSC was improved to 14.83% accompanied with V(OC), J(SC), and FF being 1.08 V, 20.06 mA cm(-2), and 0.685, respectively.

  1. Magnesium-doped Zinc Oxide as Electron Selective Contact Layers for Efficient Perovskite Solar Cells.

    Science.gov (United States)

    Song, Jiaxing; Zheng, Enqiang; Liu, Leijing; Wang, Xiao-Feng; Chen, Gang; Tian, Wenjing; Miyasaka, Tsutomu

    2016-09-22

    The electron-selective contact layer (ESL) in organometal halide-based perovskite solar cells (PSCs) determines not only the power conversion efficiency (PCE) but also the thermostability of PSCs. To improve the thermostability of ZnO-based PSCs, we developed Mg-doped ZnO [Zn 1-x Mg x O (ZMO)] as a high optical transmittance ESL for the methylammonium lead trihalide perovskite absorber [CH 3 NH 3 PbI 3 ]. We further investigated the optical and electrical properties of the ESL films with Mg contents of 0-30 mol % and the corresponding devices. We achieved a maximum PCE of 16.5 % with improved thermal stability of CH 3 NH 3 PbI 3 on ESL with the optimal ZMO (0.4 m) containing 10 mol % Mg. Moreover, this optimized ZMO PSC exhibited significantly improved durability and photostability owing to the improved chemical/photochemical stability of the wider optical bandgap ZMO. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. Transmission Electron Microscopy Studies of Electron-Selective Titanium Oxide Contacts in Silicon Solar Cells

    KAUST Repository

    Ali, Haider

    2017-08-15

    In this study, the cross-section of electron-selective titanium oxide (TiO2) contacts for n-type crystalline silicon solar cells were investigated by transmission electron microscopy. It was revealed that the excellent cell efficiency of 21.6% obtained on n-type cells, featuring SiO2/TiO2/Al rear contacts and after forming gas annealing (FGA) at 350°C, is due to strong surface passivation of SiO2/TiO2 stack as well as low contact resistivity at the Si/SiO2/TiO2 heterojunction. This can be attributed to the transformation of amorphous TiO2 to a conducting TiO2-x phase. Conversely, the low efficiency (9.8%) obtained on cells featuring an a-Si:H/TiO2/Al rear contact is due to severe degradation of passivation of the a-Si:H upon FGA.

  3. All-optical OFDM system using a wavelength selective switch based transmitter and a spectral magnification based receiver

    DEFF Research Database (Denmark)

    Guan, Pengyu; Lefrancois, S.; Lillieholm, Mads

    2014-01-01

    We demonstrate an AO-OFDM system with a WSS-based transmitter and time-lens based receiver for spectral magnification, achieving BER~10-9 for a 28×10 Gbit/s DPSK AO-OFDM signal. Furthermore, the receiver performance for DPSK and DQPSK is investigated using Monte Carlo simulations....

  4. Theoretical Insight into the Spectral Characteristics of Fe(II-Based Complexes for Dye-Sensitized Solar Cells—Part I: Polypyridyl Ancillary Ligands

    Directory of Open Access Journals (Sweden)

    Xiaoqing Lu

    2011-01-01

    Full Text Available The design of light-absorbent dyes with cheaper, safer, and more sustainable materials is one of the key issues for the future development of dye-sensitized solar cells (DSSCs. We report herein a theoretical investigation on a series of polypyridyl Fe(II-based complexes of FeL2(SCN2, [FeL3]2+, [FeL′(SCN3]-, [FeL′2]2+, and FeL′′(SCN2 (L = 2,2′-bipyridyl-4,4′-dicarboxylic acid, L′ = 2,2′,2″-terpyridyl-4,4′,4″-tricarboxylic acid, L″ = 4,4‴-dimethyl-2,2′ : 6′,2″ :6″,2‴-quaterpyridyl-4′,4″-biscarboxylic acid by density functional theory (DFT and time-dependent DFT (TD-DFT. Molecular geometries, electronic structures, and optical absorption spectra are predicted in both the gas phase and methyl cyanide (MeCN solution. Our results show that polypyridyl Fe(II-based complexes display multitransition characters of Fe → polypyridine metal-to-ligand charge transfer and ligand-to-ligand charge transfer in the range of 350–800 nm. Structural optimizations by choosing different polypyridyl ancillary ligands lead to alterations of the molecular orbital energies, oscillator strength, and spectral response range. Compared with Ru(II sensitizers, Fe(II-based complexes show similar characteristics and improving trend of optical absorption spectra along with the introduction of different polypyridyl ancillary ligands.

  5. X-ray spectral modelling of the AGN obscuring region in the CDFS: Bayesian model selection and catalogue

    Science.gov (United States)

    Buchner, J.; Georgakakis, A.; Nandra, K.; Hsu, L.; Rangel, C.; Brightman, M.; Merloni, A.; Salvato, M.; Donley, J.; Kocevski, D.

    2014-04-01

    Context. Aims: Active galactic nuclei are known to have complex X-ray spectra that depend on both the properties of the accreting super-massive black hole (e.g. mass, accretion rate) and the distribution of obscuring material in its vicinity (i.e. the "torus"). Often however, simple and even unphysical models are adopted to represent the X-ray spectra of AGN, which do not capture the complexity and diversity of the observations. In the case of blank field surveys in particular, this should have an impact on e.g. the determination of the AGN luminosity function, the inferred accretion history of the Universe and also on our understanding of the relation between AGN and their host galaxies. Methods: We develop a Bayesian framework for model comparison and parameter estimation of X-ray spectra. We take into account uncertainties associated with both the Poisson nature of X-ray data and the determination of source redshift using photometric methods. We also demonstrate how Bayesian model comparison can be used to select among ten different physically motivated X-ray spectral models the one that provides a better representation of the observations. This methodology is applied to X-ray AGN in the 4 Ms Chandra Deep Field South. Results: For the ~350 AGN in that field, our analysis identifies four components needed to represent the diversity of the observed X-ray spectra: (1) an intrinsic power law; (2) a cold obscurer which reprocesses the radiation due to photo-electric absorption, Compton scattering and Fe-K fluorescence; (3) an unabsorbed power law associated with Thomson scattering off ionised clouds; and (4) Compton reflection, most noticeable from a stronger-than-expected Fe-K line. Simpler models, such as a photo-electrically absorbed power law with a Thomson scattering component, are ruled out with decisive evidence (B > 100). We also find that ignoring the Thomson scattering component results in underestimation of the inferred column density, NH, of the obscurer

  6. THE CHANDRA MULTI-WAVELENGTH PROJECT: OPTICAL SPECTROSCOPY AND THE BROADBAND SPECTRAL ENERGY DISTRIBUTIONS OF X-RAY-SELECTED AGNs

    Energy Technology Data Exchange (ETDEWEB)

    Trichas, Markos; Green, Paul J.; Aldcroft, Tom; Kim, Dong-Woo; Mossman, Amy [Harvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138 (United States); Silverman, John D. [Institute for the Physics and Mathematics of the Universe (IPMU), University of Tokyo, Kashiwanoha 5-1-5, Kashiwa-shi, Chiba 277-8568 (Japan); Barkhouse, Wayne [Department of Physics and Astrophysics, University of North Dakota, Grand Forks, ND 58202 (United States); Cameron, Robert A. [W. W. Hansen Experimental Physics Laboratory, Kavli Institute for Particle Astrophysics and Cosmology, Department of Physics and SLAC National Accelerator Laboratory, Stanford University, Stanford, CA 94305 (United States); Constantin, Anca [Department of Physics and Astronomy, James Madison University, PHCH, Harrisonburg, VA 22807 (United States); Ellison, Sara L. [Department of Physics and Astronomy, University of Victoria, Victoria, BC V8P 1A1 (Canada); Foltz, Craig [Division of Astronomical Sciences, National Science Foundation, 4201 Wilson Blvd., Arlington, VA 22230 (United States); Haggard, Daryl [Center for Interdisciplinary Exploration and Research in Astrophysics, Northwestern University, 2145 Sheridan Road, Evanston, IL 60208 (United States); Jannuzi, Buell T. [NOAO, Kitt Peak National Observatory, Tucson, AZ 85726 (United States); Marshall, Herman L. [Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology, 77 Massachusetts Ave., Cambridge, MA 02139 (United States); Perez, Laura M. [Department of Astronomy, California Institute of Technology, 1200 East California Blvd, Pasadena, CA 91125 (United States); Romero-Colmenero, Encarni [South African Astronomical Observatory, P.O. Box 9, Observatory, 7935 (South Africa); Ruiz, Angel [Osservatorio Astronomico di Brera-INAF, Milan (Italy); Smith, Malcolm G., E-mail: mtrichas@cfa.harvard.edu [Cerro Tololo Interamerican Observatory, La Serena (Chile); and others

    2012-06-01

    From optical spectroscopy of X-ray sources observed as part of the Chandra Multi-wavelength Project (ChaMP), we present redshifts and classifications for a total of 1569 Chandra sources from our targeted spectroscopic follow-up using the FLWO/1.5 m, SAAO/1.9 m, WIYN 3.5 m, CTIO/4 m, KPNO/4 m, Magellan/6.5 m, MMT/6.5 m, and Gemini/8 m telescopes, and from archival Sloan Digital Sky Survey (SDSS) spectroscopy. We classify the optical counterparts as 50% broad-line active galactic nuclei (AGNs), 16% emission line galaxies, 14% absorption line galaxies, and 20% stars. We detect QSOs out to z {approx} 5.5 and galaxies out to z {approx} 3. We have compiled extensive photometry, including X-ray (ChaMP), ultraviolet (GALEX), optical (SDSS and ChaMP-NOAO/MOSAIC follow-up), near-infrared (UKIDSS, Two Micron All Sky Survey, and ChaMP-CTIO/ISPI follow-up), mid-infrared (WISE), and radio (FIRST and NVSS) bands. Together with our spectroscopic information, this enables us to derive detailed spectral energy distributions (SEDs) for our extragalactic sources. We fit a variety of template SEDs to determine bolometric luminosities, and to constrain AGNs and starburst components where both are present. While {approx}58% of X-ray Seyferts (10{sup 42} erg s{sup -1} < L{sub 2-10keV} <10{sup 44} erg s{sup -1}) require a starburst event (>5% starburst contribution to bolometric luminosity) to fit observed photometry only 26% of the X-ray QSO (L{sub 2-10keV} >10{sup 44} erg s{sup -1}) population appear to have some kind of star formation contribution. This is significantly lower than for the Seyferts, especially if we take into account torus contamination at z > 1 where the majority of our X-ray QSOs lie. In addition, we observe a rapid drop of the percentage of starburst contribution as X-ray luminosity increases. This is consistent with the quenching of star formation by powerful QSOs, as predicted by the merger model, or with a time lag between the peak of star formation and QSO

  7. The Solar Photospheric Nitrogen Abundance : Determination with 3D and 1D Model Atmospheres

    NARCIS (Netherlands)

    Maiorca, E.; Caffau, E.; Bonifacio, P.; Busso, M.; Faraggiana, R.; Steffen, M.; Ludwig, H. -G.; Kamp, I.

    2009-01-01

    We present a new determination of the solar nitrogen abundance making use of 3D hydrodynamical modelling of the solar photosphere, which is more physically motivated than traditional static 1D models. We selected suitable atomic spectral lines, relying on equivalent width measurements already

  8. Local Environment and Interactions of Liquid and Solid Interfaces Revealed by Spectral Line Shape of Surface Selective Nonlinear Vibrational Probe

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Shun-Li; Fu, Li; Chase, Zizwe A.; Gan, Wei; Wang, Hong-Fei

    2016-11-10

    Vibrational spectral lineshape contains important detailed information of molecular vibration and reports its specific interactions and couplings to its local environment. In this work, recently developed sub-1 cm-1 high-resolution broadband sum frequency generation vibrational spectroscopy (HR-BB-SFG-VS) was used to measure the -C≡N stretch vibration in the 4-n-octyl-4’-cyanobiphenyl (8CB) Langmuir or Langmuir-Blodgett (LB) monolayer as a unique vibrational probe, and the spectral lineshape analysis revealed the local environment and interactions at the air/water, air/glass, air/calcium fluoride and air/-quartz interfaces for the first time. The 8CB Langmuir or LB film is uniform and the vibrational spectral lineshape of its -C≡N group has been well characterized, making it a good choice as the surface vibrational probe. Lineshape analysis of the 8CB -C≡N stretch SFG vibrational spectra suggests the coherent vibrational dynamics and the structural and dynamic inhomogeneity of the -C≡N group at each interface are uniquely different. In addition, it is also found that there are significantly different roles for water molecules in the LB films on different substrate surfaces. These results demonstrated the novel capabilities of the surface nonlinear spectroscopy in characterization and in understanding the specific structures and chemical interactions at the liquid and solid interfaces in general.

  9. Assessment of relevant hepatic steatosis in obese adolescents by rapid fat-selective GRE imaging with spatial-spectral excitation: a quantitative comparison with spectroscopic findings

    International Nuclear Information System (INIS)

    Springer, Fabian; Schick, Fritz; Ehehalt, Stefan; Binder, Gerhard; Sommer, Julia; Ballweg, Verena; Machann, Juergen; Claussen, Claus D.

    2011-01-01

    To test the feasibility of fat-selective GRE imaging using a spectral-spatial excitation technique for determination of intrahepatic lipid content (IHL) in obese adolescents. Fat-selective MR imaging (1.5 T) was applied to record a single axial slice through a representative liver region within a single breath-hold. The sequence uses six equidistant slice-selective excitation pulses with binomial amplitude ratios to achieve high selectivity for lipid signals after appropriate shimming. IHL MRI content was quantified using signal intensity of adjacent subcutaneous adipose tissue. As the gold standard for IHL quantification, single-voxel stimulated echo magnetic resonance spectroscopy (MRS) was applied. IHL MRS was quantified using the water peak as a reference. Forty-five MR examinations could be performed, and IHL MRS content ranged from 0.7% to 19.1%. Results from MRS and fat-selective imaging correlated well with Spearman coefficients between r = 0.78 and r = 0.86. There were no relevant regional differences in IHL within the liver parenchyma (p > 0.6359). Fat-selective imaging was able to reliably identify patients with IHL content above 5% with positive/negative likelihood ratio of 11.8 and 0.05, respectively. Fat-selective MR imaging provides both a reliable and a convenient method of rapidly quantifying IHL content in obese adolescents. (orig.)

  10. Wavelength-Selective Solar Photovoltaic Systems: Powering Greenhouses for Plant Growth at the Food-Energy-Water Nexus

    Science.gov (United States)

    Loik, Michael E.; Carter, Sue A.; Alers, Glenn; Wade, Catherine E.; Shugar, David; Corrado, Carley; Jokerst, Devin; Kitayama, Carol

    2017-10-01

    Global renewable electricity generation capacity has rapidly increased in the past decade. Increasing the sustainability of electricity generation and the market share of solar photovoltaics (PV) will require continued cost reductions or higher efficiencies. Wavelength-Selective Photovoltaic Systems (WSPVs) combine luminescent solar cell technology with conventional silicon-based PV, thereby increasing efficiency and lowering the cost of electricity generation. WSPVs absorb some of the blue and green wavelengths of the solar spectrum but transmit the remaining wavelengths that can be utilized by photosynthesis for plants growing below. WSPVs are ideal for integrating electricity generation with glasshouse production, but it is not clear how they may affect plant development and physiological processes. The effects of tomato photosynthesis under WSPVs showed a small decrease in water use, whereas there were minimal effects on the number and fresh weight of fruit for a number of commercial species. Although more research is required on the impacts of WSPVs, they are a promising technology for greater integration of distributed electricity generation with food production operations, for reducing water loss in crops grown in controlled environments, as building-integrated solar facilities, or as alternatives to high-impact PV for energy generation over agricultural or natural ecosystems.

  11. A Non-Ventilated Solar Façade Concept Based on Selective and Transparent Insulation Material Integration: An Experimental Study

    Directory of Open Access Journals (Sweden)

    Miroslav Čekon

    2017-06-01

    Full Text Available A new solar façade concept based on transparent insulation and a selective absorber is proposed, tested and compared with conventional insulation and a non-selective type of absorber, respectively. The presented study focuses on an experimental non-ventilated solar type of façade exposed to solar radiation both in the laboratory and in outdoor tests. Due to the high solar absorbance level of the façade, high- and low-emissivity contributions were primarily analysed. All of the implemented materials were contrasted from the thermal and optical point of view. An analysis was made of both thermodynamic and steady state procedures affecting the proposed solar façade concept. Experimental full scale tests on real building components were additionally involved during summer monitoring. An indicator of the temperature response generated by solar radiation exposure demonstrates the outdoor performance of the façade is closely related to overheating phenomena. From the thermal point of view, the proposed transparent insulation and selective absorber concept corresponds to the performance of conventional thermal insulation of identical material thickness; however, the non-selective prototype only provides 50% thermal performance. The results of the solar-based experiments show that with a small-scale experimental prototype, approximately no significant difference is measured when compared with a non-selective absorber type. The only difference was achieved at the maximum of 2.5 K, when the lower temperature was obtained in the solar selective concept. At the full-scale outdoor mode, the results indicate a maximum of 3.0 K difference, however the lower temperature achieves a non-selective approach. This solar façade can actively contribute to the thermal performance of building components during periods of heating.

  12. Application of a temperature selective storage tank solar system. Part 4. Fundamental experiment under a solar simulator; Ondo sentaku chikunetsuso no solar system eno tekiyo. 4. Solar simulator ni yoru kiso jikken

    Energy Technology Data Exchange (ETDEWEB)

    Kanayama, K.; Endo, N.; Baba, H.; Okamoto, A. [Kitami Institute of Technology, Hokkaido (Japan); Kamiya, Y. [Kanto Gakuin University, Yokohama (Japan)

    1996-10-27

    The storage tank is classified into a mixed type and stratified type. The stratified type is judged to be more advantageous from a viewpoint of the effective energy utilization. An experiment was made using a solar simulator to put the system, consisting of a vacuum double-glass tube collector and temperature selective storage tank, to practical use. The ejection position of the storage tank at the top is superior to that at the bottom, in the 60{degree}C layer of three layers (60, 40, and 20{degree}C). The ejection position hardly varies with the shape (straight or elbow) of an ejection port. When the temperature stratified layer is formed in two layers (40 {times} 2, 20{degree}C) to three layers (60, 40, and 20{degree}C), heat can be stably stored as the flow rate is higher. The stratified storage tank is inferior to the mixed storage tank in heat collection efficiency, but the specific exergy increases. By increasing the number of heat storage layers, the result of this experiment can also be applied to the linear temperature gradient layer obtained in the practical use. As a result of the above experiment, the basic data for an automated system design during practical application was obtained. 3 refs., 15 figs.

  13. GIS-BASED SOLAR AND WIND TURBINE SITE SELECTION USING MULTI-CRITERIA ANALYSIS: CASE STUDY TEHRAN, IRAN

    Directory of Open Access Journals (Sweden)

    M. Sadeghi

    2017-09-01

    Full Text Available Renewable energy has less negative impacts on environment than fossil fuels. Iran has many resources for renewable energy exploitation but because of their high price, it has not been developed. Site selection is an important step for utilizing large investments like solar farms and wind turbines. Multi-criteria evaluation methods are commonly used for site selection. The purpose of this paper is to determine suitable sites for solar farm and wind turbine using GIS and AHP in Tehran, in order to generate a distributed network to increase power network stability. The final land suitability index was grouped in four categories as “most suitable”, “suitable”, “moderate” and “low suitable”. As a result 94.61% (789939.63 km2 is low suitable, 4.47% (37337.17 km2 is moderate, 0.59% (4964.22 km2 is suitable and 0.32% (2680.70 km2 is the most suitable for building wind turbine and for solar farm, 44.07% (8116.88 km2 is low suitable, 12.81% (2359.79 km2 is moderate, 35.10% (6464.29 km2 is suitable and 8.02% (1477.28 km2 is the most suitable.

  14. Gis-Based Solar and Wind Turbine Site Selection Using Multi-Criteria Analysis: Case Study Tehran, Iran

    Science.gov (United States)

    Sadeghi, M.; Karimi, M.

    2017-09-01

    Renewable energy has less negative impacts on environment than fossil fuels. Iran has many resources for renewable energy exploitation but because of their high price, it has not been developed. Site selection is an important step for utilizing large investments like solar farms and wind turbines. Multi-criteria evaluation methods are commonly used for site selection. The purpose of this paper is to determine suitable sites for solar farm and wind turbine using GIS and AHP in Tehran, in order to generate a distributed network to increase power network stability. The final land suitability index was grouped in four categories as "most suitable", "suitable", "moderate" and "low suitable". As a result 94.61% (789939.63 km2) is low suitable, 4.47% (37337.17 km2) is moderate, 0.59% (4964.22 km2) is suitable and 0.32% (2680.70 km2) is the most suitable for building wind turbine and for solar farm, 44.07% (8116.88 km2) is low suitable, 12.81% (2359.79 km2) is moderate, 35.10% (6464.29 km2) is suitable and 8.02% (1477.28 km2) is the most suitable.

  15. Simple processing of back-contacted silicon heterojunction solar cells using selective-area crystalline growth

    KAUST Repository

    Tomasi, Andrea

    2017-04-24

    For crystalline-silicon solar cells, voltages close to the theoretical limit are nowadays readily achievable when using passivating contacts. Conversely, maximal current generation requires the integration of the electron and hole contacts at the back of the solar cell to liberate its front from any shadowing loss. Recently, the world-record efficiency for crystalline-silicon single-junction solar cells was achieved by merging these two approaches in a single device; however, the complexity of fabricating this class of devices raises concerns about their commercial potential. Here we show a contacting method that substantially simplifies the architecture and fabrication of back-contacted silicon solar cells. We exploit the surface-dependent growth of silicon thin films, deposited by plasma processes, to eliminate the patterning of one of the doped carrier-collecting layers. Then, using only one alignment step for electrode definition, we fabricate a proof-of-concept 9-cm2 tunnel-interdigitated back-contact solar cell with a certified conversion efficiency >22.5%.

  16. Comparison of solar-thermal and fossil total-energy systems for selected industrial applications

    Science.gov (United States)

    Pine, G. D.

    1980-06-01

    Economic analyses of a conventional system and total energy systems based on phosphoric acid fuel cells, diesel piston engines, and central receiver solar thermal systems were performed for each of four industrial applications; a concrete block plant in Arizona, a fluid milk processing plant in California, a sugar beet processing plant in Colorado, and a meat packing plant in Texas. A series of sensitivity analyses was performed to show the effects of variations in fuel price, system size, cost of capital, and system initial cost. Solar total energy systems (STES) are more capital intensive than the other systems, and significant economies of scale are associated with the STES. If DOE solar system cost goals are met, STES can compete with the other systems for facilities with electrical demands greater than two or three megawatts, but STES are not competitive for smaller facilities. Significant energy resource savings, especially of oil and gas, resulted from STES implementation in the four industries.

  17. Design and realization of a hard X-ray prototype imager with spectral selection for the Laser MegaJoule

    International Nuclear Information System (INIS)

    Dennetiere, David

    2012-01-01

    In the Laser MegaJoule (LMJ) project context, measurements need to be done by diagnostics in order to achieve ignition. Amongst these diagnostics, some of the X-ray imagers will have to observe hydrodynamics instabilities on the micron balloon surface. X-ray radiography or self-emission imaging are the techniques used to obtain such imaging. None of the existing X-ray imagers designed for LMJ is currently able to record this kind of image. The X-ray imager designed during this thesis will have to achieve a high resolution image at high energy and will have to meet all the requirements subsequent to its use on a large facility like LMJ. We have studied and optimized an already existing diagnostic: EHRXI. We have extended its covered spectral range up to 12 keV. We measured its resolution that is under 5 μm in a 1 mm diameter field of view. This diagnostic has been successfully used on laser experiments in ELFIE 100 TW and OMEGA. After analyzing the performances and weaknesses of EHRXI, we were able to design a LMJ diagnostic prototype: Merssix. This microscope will achieve a resolution under 5 μm in a 500 μm diameter field of view with a covered spectral range up to 22 keV. Merssix has been specifically designed for LMJ and adapted to fit its experimental framework. Its design allows it in particular to be used for radiography in a complex X-ray producing environment. (author) [fr

  18. Modeling and characterization of double resonant tunneling diodes for application as energy selective contacts in hot carrier solar cells

    Science.gov (United States)

    Jehl, Zacharie; Suchet, Daniel; Julian, Anatole; Bernard, Cyril; Miyashita, Naoya; Gibelli, Francois; Okada, Yoshitaka; Guillemolles, Jean-Francois

    2017-02-01

    Double resonant tunneling barriers are considered for an application as energy selective contacts in hot carrier solar cells. Experimental symmetric and asymmetric double resonant tunneling barriers are realized by molecular beam epitaxy and characterized by temperature dependent current-voltage measurements. The negative differential resistance signal is enhanced for asymmetric heterostructures, and remains unchanged between low- and room-temperatures. Within Tsu-Esaki description of the tunnel current, this observation can be explained by the voltage dependence of the tunnel transmission amplitude, which presents a resonance under finite bias for asymmetric structures. This effect is notably discussed with respect to series resistance. Different parameters related to the electronic transmission of the structure and the influence of these parameters on the current voltage characteristic are investigated, bringing insights on critical processes to optimize in double resonant tunneling barriers applied to hot carrier solar cells.

  19. Black chrome on commercially electroplated tin as a solar selecting coating

    Science.gov (United States)

    Mcdonald, G. E.

    1977-01-01

    The reflectance properties of black chrome electroplated on commercially electroplated tin were measured for various black chrome plating times for both the solar and infrared spectrum. The values of absorptance and emittance were calculated from the measured reflectance values. The results indicate that the optimum combination of the highest absorptance in the solar region and the lowest emittance in the infrared of the black chrome plated on commercially electroplated tin is obtained for a black chrome plating time of between one and two minutes.

  20. Characterization of patterns of Localized Doping Using Stamping technique for Selective n-Emitter Solar Cell Structure

    Science.gov (United States)

    Mangkornkaew, A.; Fangsuwannarak, T.

    2017-10-01

    In the present, a novel cost-effective process scheme for single step selective emitter diffusion was implemented. It is based on the fabrication of acid-resist pattern using a stamping technique with collaboration of a spin on dopant (SOD) and chemical etched-back emitter methods. The SOD diffusion process provided heavily doping n-emitter. Acid-resist pattern without exploitation of a complex method as a photolithography, was stamped as a metal contact pattern for prevention of a localized heavy-dope region from etching back. Phosphorus doping profiles were controlled by etching back time to provide the formation of n-type selective emitter. Sheet resistance is tunable from 10 to 180 Ohm/Sq on localized n-layer. After removal of the patterned acid-resist, the selective n-emitter solar cell structure was obtained under one-step diffusion to achieve a better blue-light response and low contact resistance.

  1. Selective coating for solar panels. [using black chrome and black nickel

    Science.gov (United States)

    Mcdonald, G. E. (Inventor)

    1977-01-01

    The energy absorbing properties of solar heating panels are improved by depositing a black chrome coating of controlled thickness on a specially prepared surface of a metal substrate. The surface is prepared by depositing a dull nickel on the substrate, and the black chrome is plated on this low emittance surface to a thickness between 0.5 micron and 2.5 microns.

  2. Selective solar absorbers: A cost effective solution for access to clean energy in rural Africa

    CSIR Research Space (South Africa)

    Katumba, G

    2008-11-01

    Full Text Available by inadequate grid electricity infrastructure. This state of affairs has culminated in massive deforestation and desertification of some parts of Africa. One technology solution is to harness the energy from the sun through solar absorbers. This has applications...

  3. Solar energetic particles and radio burst emission

    Directory of Open Access Journals (Sweden)

    Miteva Rositsa

    2017-01-01

    Full Text Available We present a statistical study on the observed solar radio burst emission associated with the origin of in situ detected solar energetic particles. Several proton event catalogs in the period 1996–2016 are used. At the time of appearance of the particle origin (flare and coronal mass ejection we identified radio burst signatures of types II, III and IV by inspecting dynamic radio spectral plots. The information from observatory reports is also accounted for during the analysis. The occurrence of solar radio burst signatures is evaluated within selected wavelength ranges during the solar cycle 23 and the ongoing 24. Finally, we present the burst occurrence trends with respect to the intensity of the proton events and the location of their solar origin.

  4. Solar energetic particles and radio burst emission

    Science.gov (United States)

    Miteva, Rositsa; Samwel, Susan W.; Krupar, Vratislav

    2017-12-01

    We present a statistical study on the observed solar radio burst emission associated with the origin of in situ detected solar energetic particles. Several proton event catalogs in the period 1996-2016 are used. At the time of appearance of the particle origin (flare and coronal mass ejection) we identified radio burst signatures of types II, III and IV by inspecting dynamic radio spectral plots. The information from observatory reports is also accounted for during the analysis. The occurrence of solar radio burst signatures is evaluated within selected wavelength ranges during the solar cycle 23 and the ongoing 24. Finally, we present the burst occurrence trends with respect to the intensity of the proton events and the location of their solar origin.

  5. Tunnel oxide passivated rear contact for large area n-type front junction silicon solar cells providing excellent carrier selectivity

    Directory of Open Access Journals (Sweden)

    Yuguo Tao

    2016-01-01

    Full Text Available Carrier-selective contact with low minority carrier recombination and efficient majority carrier transport is mandatory to eliminate metal-induced recombination for higher energy conversion efficiency for silicon (Si solar cells. In the present study, the carrier-selective contact consists of an ultra-thin tunnel oxide and a phosphorus-doped polycrystalline Si (poly-Si thin film formed by plasma enhanced chemical vapor deposition (PECVD and subsequent thermal crystallization. It is shown that the poly-Si film properties (doping level, crystallization and dopant activation anneal temperature are crucial for achieving excellent contact passivation quality. It is also demonstrated quantitatively that the tunnel oxide plays a critical role in this tunnel oxide passivated contact (TOPCON scheme to realize desired carrier selectivity. Presence of tunnel oxide increases the implied Voc (iVoc by ~ 125 mV. The iVoc value as high as 728 mV is achieved on symmetric structure with TOPCON on both sides. Large area (239 cm2 n-type Czochralski (Cz Si solar cells are fabricated with homogeneous implanted boron emitter and screen-printed contact on the front and TOPCON on the back, achieving 21.2% cell efficiency. Detailed analysis shows that the performance of these cells is mainly limited by boron emitter recombination on the front side.

  6. Effect of altitude on solar UVR and spectral and spatial variations of UV irradiances measured inWagrain, Austria in winter

    DEFF Research Database (Denmark)

    Baczynska, Katarzyna A; Pearson, Andy J; O'Hagan, John B

    2013-01-01

    Ultraviolet radiation spectral irradiance was measured at different altitudes on horizontal and tilted planes in different azimuth directions on cloudless days in Austria, in March 2010, within the Impact of Climatic and Environmental factors on Personal Ultraviolet Radiation Exposure project...

  7. W/Cu thin film infrared reflector for TiNxOy based selective solar absorber with high thermal stability

    Science.gov (United States)

    Zhang, J.; Chen, T. P.; Liu, Y. C.; Liu, Z.; Yang, H. Y.

    2017-05-01

    The W/Cu thin film structure is deposited by magnetron sputtering to form the infrared reflector for the TiNxOy based selective solar absorber (SSA) that can be used in the low- and middle-temperature applications. The structural, chemical, and optical properties of the SSA layers that experienced thermal annealing at different temperatures for various durations have been investigated with the characterization techniques, including X-ray photoelectron spectroscopy, X-ray diffraction, atomic force microscopy, spectroscopic ellipsometry, and spectrophotometry. Without a W layer, the reflectance in both visible and infrared ranges of the SSA increases as a result of the crystallization of the Cu layer at elevated temperatures. With a W layer with appropriate film thickness, the increase of the reflectance in the visible range can be suppressed to maintain a high solar absorptance, whereas a high infrared reflectance can be maintained to achieve a low thermal emittance. It is shown that for the SiO2-TiNxOy-W-Cu-Glass SSA with a 15 nm W thin film, thermal annealing can significantly reduce the thermal emittance to a low value (e.g., 4.4% at the temperature of 400 °C for annealing at 400 °C for 6 h), whereas the solar absorptance can be maintained at a high value (e.g., 92.2% for the annealing at 400 °C for 6 h).

  8. Spectral sensitization of TiO2 by new hemicyanine dyes in dye solar cell yielding enhanced photovoltage: Probing chain length effect on performance

    International Nuclear Information System (INIS)

    Fadadu, Kishan B.; Soni, Saurabh S.

    2013-01-01

    Graphical abstract: New hemicyanine dyes based on indolenine moiety were utilized as light harvesting materials in dye sensitized solar cell. Chain lengths of the molecules were varied in order to study its effect of chain length on the performance of DSSC. Electron transfer kinetic of the solar cell was studied and it was found that the chain length changes the electron transfer kinetic. We have achieved remarkable photovoltage and overall performance of DSSC. Highlights: ► New hemicyanine dyes based on indolenine moiety were utilized as light harvesting materials in dye sensitized solar cell. ► Chain lengths of the molecules were varied in order to study its effect of chain length on the performance of DSSC. ► Electron transfer kinetic of the solar cell was studied and it was found that the chain length changes the electron transfer kinetic. -- Abstract: New hemicyanine dyes having indole nucleus with different alkyl chain length were synthesized and characterized using 1 H NMR and mass spectroscopy. These dyes were used to sensitize the TiO 2 film in dye sensitized solar cell. Nanocrystalline dye solar cells were fabricated and characterized using various electrochemical techniques. It has been found that the alkyl chain length present in the dye molecules greatly affects the overall performance of dye solar cell. Molecules having longer alkyl chain are having better sensitizers which enhance V oc to significant extent. Chain length dependent performance was further investigated using Tafel polarization and impedance method. Hemicyanine dye having hexyl chain has outperformed by attaining 2.9% solar to electricity conversion efficiency

  9. Lanthanum hexaboride for solar energy applications.

    Science.gov (United States)

    Sani, Elisa; Mercatelli, Luca; Meucci, Marco; Zoli, Luca; Sciti, Diletta

    2017-04-06

    We investigate the optical properties of LaB 6 - based materials, as possible candidates for solid absorbers in Concentrating Solar Power (CSP) systems. Bulk LaB 6 materials were thermally consolidated by hot pressing starting from commercial powders. To assess the solar absorbance and spectral selectivity properties, room-temperature hemispherical reflectance spectra were measured from the ultraviolet to the mid-infrared, considering different compositions, porosities and surface roughnesses. Thermal emittance at around 1100 K has been measured. Experimental results showed that LaB 6 can have a solar absorbance comparable to that of the most advanced solar absorber material in actual plants such as Silicon Carbide, with a higher spectral selectivity. Moreover, LaB 6 has also the appealing characteristics to be a thermionic material, so that it could act at the same time both as direct high-temperature solar absorber and as electron source, significantly reducing system complexity in future concentrating solar thermionic systems and bringing a real innovation in this field.

  10. Technical developments of solar energy collectors in the Netherlands

    NARCIS (Netherlands)

    Oversloot, H.P.; Geus, A.C. de

    1996-01-01

    Recent research by TNO covered two different technical developments for thermal solar energy systems. One concerns a feasibility study into an all plastic spectral selective absorber, the other is a feasibility study for an overheating protection device based on heatpipe techniques. Earlier studies

  11. ANALYSIS OF THE POSSIBILITY OF USING SOLAR ENERGY TO POWER SELECTED MEASURING DRIVES IN AGRICULTURE

    Directory of Open Access Journals (Sweden)

    Jan Marian Kolano

    2017-01-01

    Full Text Available Mankind’s misgivings caused by the depletion of fossil fuels have accelerated research on obtaining energy from unconventional sources. One such source is the Sun. The present article reviews the possibility of using solar energy, converted in batteries of photovoltaic cells into electricity, in agriculture and farming. It should also be emphasized that it is energy friendly to the environment, whose acquisition on agricultural land, which often lacks access to the power grid, is now legitimate and profitable. This study presents the results of computer simulations in tabular and graphical form, using the PVSYST program, for a pasture water pumping system for watering grazing cattle.

  12. Strategies for increasing the efficiency of heterojunction organic solar cells: material selection and device architecture.

    Science.gov (United States)

    Heremans, Paul; Cheyns, David; Rand, Barry P

    2009-11-17

    Thin-film blends or bilayers of donor- and acceptor-type organic semiconductors form the core of heterojunction organic photovoltaic cells. Researchers measure the quality of photovoltaic cells based on their power conversion efficiency, the ratio of the electrical power that can be generated versus the power of incident solar radiation. The efficiency of organic solar cells has increased steadily in the last decade, currently reaching up to 6%. Understanding and combating the various loss mechanisms that occur in processes from optical excitation to charge collection should lead to efficiencies on the order of 10% in the near future. In organic heterojunction solar cells, the generation of photocurrent is a cascade of four steps: generation of excitons (electrically neutral bound electron-hole pairs) by photon absorption, diffusion of excitons to the heterojunction, dissociation of the excitons into free charge carriers, and transport of these carriers to the contacts. In this Account, we review our recent contributions to the understanding of the mechanisms that govern these steps. Starting from archetype donor-acceptor systems of planar small-molecule heterojunctions and solution-processed bulk heterojunctions, we outline our search for alternative materials and device architectures. We show that non-planar phthalocynanines have appealing absorption characteristics but also have reduced charge carrier transport. As a result, the donor layer needs to be ultrathin, and all layers of the device have to be tuned to account for optical interference effects. Using these optimization techniques, we illustrate cells with 3.1% efficiency for the non-planar chloroboron subphthalocyanine donor. Molecules offering a better compromise between absorption and carrier mobility should allow for further improvements. We also propose a method for increasing the exciton diffusion length by converting singlet excitons into long-lived triplets. By doping a polymer with a

  13. Improvements of the Vis-NIRS Model in the Prediction of Soil Organic Matter Content Using Spectral Pretreatments, Sample Selection, and Wavelength Optimization

    Science.gov (United States)

    Lin, Z. D.; Wang, Y. B.; Wang, R. J.; Wang, L. S.; Lu, C. P.; Zhang, Z. Y.; Song, L. T.; Liu, Y.

    2017-07-01

    A total of 130 topsoil samples collected from Guoyang County, Anhui Province, China, were used to establish a Vis-NIR model for the prediction of organic matter content (OMC) in lime concretion black soils. Different spectral pretreatments were applied for minimizing the irrelevant and useless information of the spectra and increasing the spectra correlation with the measured values. Subsequently, the Kennard-Stone (KS) method and sample set partitioning based on joint x-y distances (SPXY) were used to select the training set. Successive projection algorithm (SPA) and genetic algorithm (GA) were then applied for wavelength optimization. Finally, the principal component regression (PCR) model was constructed, in which the optimal number of principal components was determined using the leave-one-out cross validation technique. The results show that the combination of the Savitzky-Golay (SG) filter for smoothing and multiplicative scatter correction (MSC) can eliminate the effect of noise and baseline drift; the SPXY method is preferable to KS in the sample selection; both the SPA and the GA can significantly reduce the number of wavelength variables and favorably increase the accuracy, especially GA, which greatly improved the prediction accuracy of soil OMC with Rcc, RMSEP, and RPD up to 0.9316, 0.2142, and 2.3195, respectively.

  14. Derivatization technique to increase the spectral selectivity of two-dimensional Fourier transform infrared focal plane array imaging: analysis of binder composition in aged oil and tempera paint.

    Science.gov (United States)

    Zumbühl, Stefan; Scherrer, Nadim C; Eggenberger, Urs

    2014-01-01

    The interpretation of standard Fourier transform infrared spectra (FT-IR) on oil-based paint samples often suffers from interfering bands of the different compounds, namely, binder, oxidative aging products, carboxylates formed during aging, and several pigments and fillers. The distinction of the aging products such as ketone and carboxylic acid functional groups pose the next problem, as these interfere with the triglyceride esters of the oil. A sample preparation and derivatization technique using gaseous sulfur tetrafluoride (SF4), was thus developed with the aim to discriminate overlapping signals and achieve a signal enhancement on superposed compounds. Of particular interest in this context is the signal elimination of the broad carboxylate bands of the typical reaction products developing during the aging processes in oil-based paints, as well as signal interference originating from several typical pigments in this spectral range. Furthermore, it is possible to distinguish the different carbonyl-containing functional groups upon selective alteration. The derivatization treatment can be applied to both microsamples and polished cross sections. It increases the selectivity of the infrared spectroscopy technique in a fundamental manner and permits the identification and two-dimensional (2D) localization of binder components in aged paint samples at the micrometer scale. The combination of SF4 derivatization with high-resolution 2D FT-IR focal plane array (FPA) imaging delivers considerable advances to the study of micro-morphological processes involving organic compounds.

  15. Comparative analysis of economic models in selected solar energy computer programs

    Science.gov (United States)

    Powell, J. W.; Barnes, K. A.

    1982-01-01

    The economic evaluation models in five computer programs widely used for analyzing solar energy systems (F-CHART 3.0, F-CHART 4.0, SOLCOST, BLAST, and DOE-2) are compared. Differences in analysis techniques and assumptions among the programs are assessed from the point of view of consistency with the Federal requirements for life cycle costing (10 CFR Part 436), effect on predicted economic performance, and optimal system size, case of use, and general applicability to diverse systems types and building types. The FEDSOL program developed by the National Bureau of Standards specifically to meet the Federal life cycle cost requirements serves as a basis for the comparison. Results of the study are illustrated in test cases of two different types of Federally owned buildings: a single family residence and a low rise office building.

  16. Application of a temperature selective heat storage tank to a solar system. Part 3. Solar heat collecting system; Ondo sentaku chikunetsuso no solar system eno tekiyo. 3. Shunetsu hoshiki ni tsuite

    Energy Technology Data Exchange (ETDEWEB)

    Kamiya, Y. [Kanto Gakuin University, Yokohama (Japan); Kanayama, K. [Kitami Institute of Technology, Hokkaido (Japan)

    1996-10-27

    The tank system and tank-less system when the temperature selective heat storage tank is applied to a solar system were considered. In the tank system, the simulation shows that the annual supplementary heat consumption is reduced as the tank capacity becomes lower. The most suitable operating time set for determining the reference time is about five hours in winter and about nine hours in summer. The annual operating time is about 6.5 hours. In the tank-less system, the most suitable minimum flow rate per solar collector area of a heating medium in Tokyo and its districts is 10 L/hm{sup 2} for both three-step flow control and constant flow control. The tank-less system is slightly lower in annual supplementary heat consumption than the tank system. For the three-step flow control, a change in the annual supplementary heat consumption is lower than that in the minimum flow rate. For the constant flow control, however, the annual supplementary heat consumption rapidly increases when the flow rate more decreases than the optimum value. The number of pump start/stop counts for the three-step flow control is less than two times as high as for the constant flow control. 4 refs., 6 figs., 1 tab.

  17. Performance Comparisons and Down Selection of Small Motors for Two-Blade Heliogyro Solar Sail 6U CubeSat

    Science.gov (United States)

    Wiwattananon, Peerawan; Bryant, Robert G.

    2015-01-01

    This report compiles a review of 130 commercial small scale motors (piezoelectric and electric motors) and almost 20 researched-type small scale piezoelectricmotors for potential use in a 2 blades Heliogyro Solar Sail 6U CubeSat. In this application, a motor and gearhead (drive system) will deploy a roll of solar sailthin film (2 um thick)accommodated in a 2U CubeSat (100 x 200 x 100 mm) housing. The application requirements are: space rated, output torque at fulldeployment of 0.8 Nm, reel speed of 3 rpm, drive system weight limited to 150 grams, diameter limited to 50 mm, and the length not to exceed 40 mm. The 50mm diameter limit was imposed as motors with larger diameters would likely weigh too much and use more space on the satellite wall. This would limit theamount of the payload. The motors performance are compared between small scale, volume within 3x102 cm3 (3x105 mm3), commercial electric DC motors,commercial piezoelectric motors, and researched-type (non-commercial) piezoelectric motors extracted from scientific and product literature. The comparisonssuggest that piezoelectric motors without a gearhead exhibit larger output torque with respect to their volume and weight and require less input power toproduce high torque. A commercially available electric motor plus a gearhead was chosen through a proposed selection process to meet the applications designrequirements.

  18. Plasma Beta Dependence of the Ion-scale Spectral Break of Solar Wind Turbulence: High-resolution 2D Hybrid Simulations

    Czech Academy of Sciences Publication Activity Database

    Franci, L.; Landi, S.; Matteini, L.; Verdini, A.; Hellinger, Petr

    2016-01-01

    Roč. 833, č. 1 (2016), 91/1-91/7 ISSN 0004-637X R&D Projects: GA ČR GA15-10057S Institutional support: RVO:67985815 Keywords : plasmas * solar wind * turbulence Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics Impact factor: 5.533, year: 2016

  19. Selection of high temperature thermal energy storage materials for advanced solar dynamic space power systems

    Science.gov (United States)

    Lacy, Dovie E.; Coles-Hamilton, Carolyn; Juhasz, Albert

    1987-01-01

    Under the direction of NASA's Office of Aeronautics and Technology (OAST), the NASA Lewis Research Center has initiated an in-house thermal energy storage program to identify combinations of phase change thermal energy storage media for use with a Brayton and Stirling Advanced Solar Dynamic (ASD) space power system operating between 1070 and 1400 K. A study has been initiated to determine suitable combinations of thermal energy storage (TES) phase change materials (PCM) that result in the smallest and lightest weight ASD power system possible. To date the heats of fusion of several fluoride salt mixtures with melting points greater than 1025 K have been verified experimentally. The study has indicated that these salt systems produce large ASD systems because of their inherent low thermal conductivity and low density. It is desirable to have PCMs with high densities and high thermal conductivities. Therefore, alternate phase change materials based on metallic alloy systems are also being considered as possible TES candidates for future ASD space power systems.

  20. High-temperature thermal storage systems for advanced solar receivers materials selections

    Science.gov (United States)

    Wilson, D. F.; Devan, J. H.; Howell, M.

    1990-01-01

    Advanced space power systems that use solar energy and Brayton or Stirling heat engines require thermal energy storage (TES) systems to operate continuously through periods of shade. The receiver storage units, key elements in both Brayton and Stirling systems, are designed to use the latent heat of fusion of phase-change materials (PCMs). The power systems under current consideration for near-future National Aeronautics and Space Administration space missions require working fluid temperatures in the 1100 to 1400 K range. The PCMs under current investigation that gave liquid temperatures within this range are the fluoride family of salts. However, these salts have low thermal conductivity, which causes large temperature gradients in the storage systems. Improvements can be obtained, however, with the use of thermal conductivity enhancements or metallic PCMs. In fact, if suitable containment materials can be found, the use of metallic PCMs would virtually eliminate the orbit associated temperature variations in TES systems. The high thermal conductivity and generally low volume change on melting of germanium and alloys based on silicon make them attractive for storage of thermal energy in space power systems. An approach to solving the containment problem, involving both chemical and physical compatibility, preparation of NiSi/NiSi2, and initial results for containment of germanium and NiSi/NiSi2, are presented.

  1. Solar Light Photocatalytic CO2 Reduction: General Considerations and Selected Bench-Mark Photocatalysts

    Directory of Open Access Journals (Sweden)

    Ștefan Neațu

    2014-03-01

    Full Text Available The reduction of carbon dioxide to useful chemicals has received a great deal of attention as an alternative to the depletion of fossil resources without altering the atmospheric CO2 balance. As the chemical reduction of CO2 is energetically uphill due to its remarkable thermodynamic stability, this process requires a significant transfer of energy. Achievements in the fields of photocatalysis during the last decade sparked increased interest in the possibility of using sunlight to reduce CO2. In this review we discuss some general features associated with the photocatalytic reduction of CO2 for the production of solar fuels, with considerations to be taken into account of the photocatalyst design, of the limitations arising from the lack of visible light response of titania, of the use of co-catalysts to overcome this shortcoming, together with several strategies that have been applied to enhance the photocatalytic efficiency of CO2 reduction. The aim is not to provide an exhaustive review of the area, but to present general aspects to be considered, and then to outline which are currently the most efficient photocatalytic systems.

  2. Concentrated Solar Thermoelectric Power

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Gang [MIT; Ren, Zhifeng [University of Houston

    2015-07-09

    The goal of this project is to demonstrate in the lab that solar thermoelectric generators (STEGs) can exceed 10% solar-to-electricity efficiency, and STEGs can be integrated with phase-change materials (PCM) for thermal storage, providing operation beyond daylight hours. This project achieved significant progress in many tasks necessary to achieving the overall project goals. An accurate Themoelectric Generator (TEG) model was developed, which included realistic treatment of contact materials, contact resistances and radiative losses. In terms of fabricating physical TEGs, high performance contact materials for skutterudite TE segments were developed, along with brazing and soldering methods to assemble segmented TEGs. Accurate measurement systems for determining device performance (in addition to just TE material performance) were built for this project and used to characterize our TEGs. From the optical components’ side, a spectrally selective cermet surface was developed with high solar absorptance and low thermal emittance, with thermal stability at high temperature. A measurement technique was also developed to determine absorptance and total hemispherical emittance at high temperature, and was used to characterize the fabricated spectrally selective surfaces. In addition, a novel reflective cavity was designed to reduce radiative absorber losses and achieve high receiver efficiency at low concentration ratios. A prototype cavity demonstrated that large reductions in radiative losses were possible through this technique. For the overall concentrating STEG system, a number of devices were fabricated and tested in a custom built test platform to characterize their efficiency performance. Additionally, testing was performed with integration of PCM thermal storage, and the storage time of the lab scale system was evaluated. Our latest testing results showed a STEG efficiency of 9.6%, indicating promising potential for high performance concentrated STEGs.

  3. SPECTRAL DEPENDENT ELECTRICAL CHARACTERISTICS OF ...

    African Journals Online (AJOL)

    ABSTRACT: The illuminated current-voltage characteristics of thin film a-Si:H. p-i-n solar cells were measured for the visible and near infrared spectral regions. The fill factor, the conversion efficiency, the open circuit Voltage and the short circuit current were compared to the parameters of crystalline silicon pit-junction.

  4. Tight control of light trapping in surface addressable photonic crystal membranes: application to spectrally and spatially selective optical devices (Conference Presentation)

    Science.gov (United States)

    Letartre, Xavier; Blanchard, Cédric; Grillet, Christian; Jamois, Cécile; Leclercq, Jean-Louis; Viktorovitch, Pierre

    2016-04-01

    Surface addressable Photonic Crystal Membranes (PCM) are 1D or 2D photonic crystals formed in a slab waveguides where Bloch modes located above the light line are exploited. These modes are responsible for resonances in the reflection spectrum whose bandwidth can be adjusted at will. These resonances result from the coupling between a guided mode of the membrane and a free-space mode through the pattern of the photonic crystal. If broadband, these structures represent an ideal mirror to form compact vertical microcavity with 3D confinement of photons and polarization selectivity. Among numerous devices, low threshold VCSELs with remarkable and tunable modal properties have been demonstrated. Narrow band PCMs (or high Q resonators) have also been extensively used for surface addressable optoelectronic devices where an active material is embedded into the membrane, leading to the demonstration of low threshold surface emitting lasers, nonlinear bistables, optical traps... In this presentation, we will describe the main physical rules which govern the lifetime of photons in these resonant modes. More specifically, it will be emphasized that the Q factor of the PCM is determined, to the first order, by the integral overlap between the electromagnetic field distributions of the guided and free space modes and of the dielectric periodic perturbation which is applied to the homogeneous membrane to get the photonic crystal. It turns out that the symmetries of these distributions are of prime importance for the strength of the resonance. It will be shown that, by molding in-plane or vertical symmetries of Bloch modes, spectrally and spatially selective light absorbers or emitters can be designed. First proof of concept devices will be also presented.

  5. Solar Features - Solar Flares - Patrol

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The H-alpha Flare Patrol identifies time periods each day when the sun is being continuously monitored by select ground-based solar observatories.

  6. Water frost and ice - The near-infrared spectral reflectance 0.65-2.5 microns. [observed on natural satellites and other solar system objects

    Science.gov (United States)

    Clark, R. N.

    1981-01-01

    The spectral reflectance of water frost and frost on ice as a function of temperature and grain size is presented with 1-1/2% spectral resolution in the 0.65- to 2.5-micron wavelength region. The well-known 2.0-, 1.65-, and 1.5-micron solid water absorption bands are precisely defined along with the little studied 1.25-micron band and the previously unidentified (in reflectance) 1.04-, 0.90-, and 0.81-micron absorption bands. The 1.5-microns band complex is quantitatively analyzed using a nonlinear least squares algorithm to resolve the band into four Gaussian components as a function of grain size and temperature. It is found that the 1.65-micron component, which was thought to be a good temperature sensor, is highly grain-size dependent and poorly suited to temperature sensing. Another Gaussian component appears to show a dependence of width on grain size while being independent of temperature. The relative apparent band depths are different for frost layers on ice than for thick layers of frost and may explain the apparent band depths seen in many planetary reflectance spectra.

  7. The interaction between hybrid organic-inorganic halide perovskite and selective contacts in perovskite solar cells: an infrared spectroscopy study.

    Science.gov (United States)

    Idígoras, J; Todinova, A; Sánchez-Valencia, J R; Barranco, A; Borrás, A; Anta, J A

    2016-05-11

    The interaction of hybrid organic-inorganic halide perovskite and selective contacts is crucial to get efficient, stable and hysteresis-free perovskite-based solar cells. In this report, we analyze the vibrational properties of methylammonium lead halide perovskites deposited on different substrates by infrared absorption (IR) measurements (4000-500 cm(-1)). The materials employed as substrates are not only characterized by different chemical natures (TiO2, ZnO and Al2O3), but also by different morphologies. For all of them, we have investigated the influence of these substrate properties on perovskite formation and its degradation by humidity. The effect of selective-hole contact (Spiro-OmeTad and P3HT) layers on the degradation rate by moisture has also been studied. Our IR results reveal the existence of a strong interaction between perovskite and all ZnO materials considered, evidenced by a shift of the peaks related to the N-H vibrational modes. The interaction even induces a morphological change in ZnO nanoparticles after perovskite deposition, pointing to an acid-base reaction that takes place through the NH3(+) groups of the methylammonium cation. Our IR and X-ray diffraction results also indicate that this specific interaction favors perovskite decomposition and PbI2 formation for ZnO/perovskite films subjected to humid conditions. Although no interaction is observed for TiO2, Al2O3, and the hole selective contact, the morphology and chemical nature of both contacts appear to play an important role in the rate of degradation upon exposure to moisture.

  8. Potential Visual Impacts of Utility-Scale Solar Energy Development within Solar Energy Zones on Selected Viewpoints in Death Valley and Joshua Tree National Parks, and El Camino Real De Tierra Adentro National Historic Trail

    Energy Technology Data Exchange (ETDEWEB)

    Sullivan, Robert G. [Argonne National Lab. (ANL), Argonne, IL (United States); Abplanalp, Jennifer M. [Argonne National Lab. (ANL), Argonne, IL (United States); Cantwell, Brian L. [Argonne National Lab. (ANL), Argonne, IL (United States); Beckman, Kevin J. [Argonne National Lab. (ANL), Argonne, IL (United States)

    2013-06-01

    In connection with the Bureau of Land Management’s (BLM’s) Solar Programmatic Environmental Impact Statement (Solar PEIS), Argonne National Laboratory (Argonne) has conducted an extended visual impact analysis for selected key observation points (KOPs) within three National Park Service (NPS) units located within the 25-mi (40-km) viewshed of four solar energy zones (SEZs) identified in the Solar PEIS. The analysis includes only those NPS units that the Solar PEIS identified as potentially subject to moderate or strong visual contrasts associated with solar development within the SEZs. The NPS units included in the analysis are Death Valley and Joshua Tree National Parks and El Camino Real De Tierra Adentro National Historic Trail. The analysis showed that certain KOPs in each of these NPS units could potentially be subject to major visual contrast and impacts from solar development within the SEZs, but many of the KOPs would likely be subject to moderate, minor, or negligible contrasts and impacts, generally because they were relatively distant from the relevant SEZ, had views of the SEZ partially blocked by intervening terrain, and/or had very low vertical angles of view toward the SEZ. For all three NPS units, power tower facilities were found to be major contributors to potential visual contrasts, primarily because of the long-distance visibility of intensely bright reflection of light from the receivers on the central towers, but also because of the height and strong vertical line of the tower structures and the potential for night-sky impacts from FAA-mandated hazard navigation lighting.

  9. Solar constant values for estimating solar radiation

    International Nuclear Information System (INIS)

    Li, Huashan; Lian, Yongwang; Wang, Xianlong; Ma, Weibin; Zhao, Liang

    2011-01-01

    There are many solar constant values given and adopted by researchers, leading to confusion in estimating solar radiation. In this study, some solar constant values collected from literature for estimating solar radiation with the Angstroem-Prescott correlation are tested in China using the measured data between 1971 and 2000. According to the ranking method based on the t-statistic, a strategy to select the best solar constant value for estimating the monthly average daily global solar radiation with the Angstroem-Prescott correlation is proposed. -- Research highlights: → The effect of the solar constant on estimating solar radiation is investigated. → The investigation covers a diverse range of climate and geography in China. → A strategy to select the best solar constant for estimating radiation is proposed.

  10. Spectral quality of photo-selective nets improves phytochemicals and aroma volatiles in coriander leaves (Coriandrum sativum L.) after postharvest storage.

    Science.gov (United States)

    Buthelezi, Millicent N Duduzile; Soundy, Puffy; Jifon, John; Sivakumar, Dharini

    2016-08-01

    The influence of spectral light on leaf quality and phytochemical contents and composition of aroma compounds in coriander leaves grown for fresh use under photo-selective nets; pearl net [40% shading; and 3.88 blue/red ratio; 0.21 red/far red ratio; photosynthetic radiation (PAR) 233.24 (μmolm(-2)s(-1))] and red net [40% shading and 0.57 blue/red ratio; 0.85 red/far red ratio; 221.67 (μmolm(-2)s(-1))] were compared with commercially used black nets [25% shading; 3.32 blue/red ratio 0.96 red/far red ratio; 365.26 (μmolm(-2)s(-1))] at harvest and after 14days of storage. Black nets improved total phenols, flavonoid (quercetin) content, ascorbic acid content, and total antioxidant activity in coriander leaves at harvest. The characteristic leaf aroma compound decanal was higher in leaves from the plants under the red nets at harvest. However, coriander leaves from plants produced under red nets retained higher total phenols, flavonoids (quercetin) and antioxidant scavenging activity 14days after postharvest storage (0°C, 10days, 95% RH and retailers' shelf at 15°C for 4days, 75% RH). But production under the pearl nets improved marketable yield reduced weight loss and retained overall quality, ascorbic acid content and aroma volatile compounds in fresh coriander leaves after postharvest storage. Pearl nets thus have the potential as a pre-harvest tool to enhance the moderate retention of phytochemicals and saleable weight for fresh coriander leaves during postharvest storage. Copyright © 2016 Elsevier B.V. All rights reserved.

  11. High spectral response heteroleptic ruthenium (II) complexes as ...

    Indian Academy of Sciences (India)

    better monochromatic incident photon-to-current conversion efficiency (IPCE) across the spectral range of 400 to 800 nm with solar .... High spectral response heteroleptic ruthenium (II) complexes as sensitizers for dye sensitized solar cells. 39 ..... electrolyte increases the exchange reaction between I- and I3. − which in turn ...

  12. Effects of the selection of heat transfer fluid and condenser type on the performance of a solar thermal power plant with technoeconomic approach

    International Nuclear Information System (INIS)

    Yilmazoglu, M. Zeki

    2016-01-01

    Highlights: • The effects of the selection of HTF and condenser type on STPs were examined. • Levelized cost of energy (LCOE) for STP was investigated. • LCOE for STP compared with gas turbine and combined cycle. • CSP with thermal storage can be competitive technology with carbon tax/credits. - Abstract: Renewable electricity generation systems have an increasing trend in terms of usage due to aiming to decrease greenhouse gas emissions and energy source diversification strategies of countries. Parabolic trough, Fresnel, and solar tower systems have been used to generate solar thermal electricity around the world. In this study, the effects of the selection of collector heat transfer fluid (HTF) and condenser type on a concentrated solar thermal power plant were analyzed. Net power, net electrical efficiency, and economic analysis were carried out for the selected HTFs for different collector outlet temperature cases. In the case of condenser type selection four different systems were considered; water cooled, air cooled (dry air) and air cooled with water spraying (spraying before fan and spraying before and after fan). Levelized cost of energy (LCOE) and specific investment cost were calculated. According to the results, specific investment cost and LCOE were found to be 4000 USD/kW el and 0.207 USD/kW h, respectively. Carbon tax/credit was also included to the calculations of LCOE and a comparison study was carried out for gas turbine, combined cycle and solar thermal power plant with thermal storage. Including carbon tax/credit to the LCOE shows that solar thermal power plant with heat storage can be competitive when compared to gas turbines.

  13. Interpolating and Estimating Horizontal Diffuse Solar Irradiation to Provide UK-Wide Coverage: Selection of the Best Performing Models

    Directory of Open Access Journals (Sweden)

    Diane Palmer

    2017-02-01

    Full Text Available Plane-of-array (PoA irradiation data is a requirement to simulate the energetic performance of photovoltaic devices (PVs. Normally, solar data is only available as global horizontal irradiation, for a limited number of locations, and typically in hourly time resolution. One approach to handling this restricted data is to enhance it initially by interpolation to the location of interest; next, it must be translated to PoA data by separately considering the diffuse and the beam components. There are many methods of interpolation. This research selects ordinary kriging as the best performing technique by studying mathematical properties, experimentation and leave-one-out-cross validation. Likewise, a number of different translation models has been developed, most of them parameterised for specific measurement setups and locations. The work presented identifies the optimum approach for the UK on a national scale. The global horizontal irradiation will be split into its constituent parts. Divers separation models were tried. The results of each separation algorithm were checked against measured data distributed across the UK. It became apparent that while there is little difference between procedures (14 Wh/m2 mean bias error (MBE, 12 Wh/m2 root mean square error (RMSE, the Ridley, Boland, Lauret equation (a universal split algorithm consistently performed well. The combined interpolation/separation RMSE is 86 Wh/m2.

  14. Optimal Site Selection of Wind-Solar Complementary Power Generation Project for a Large-Scale Plug-In Charging Station

    Directory of Open Access Journals (Sweden)

    Wenjun Chen

    2017-10-01

    Full Text Available The wind-solar hybrid power generation project combined with electric vehicle charging stations can effectively reduce the impact on the power system caused by the random charging of electric cars, contribute to the in-situ wind-solar complementary system and reduce the harm arising from its output volatility. In this paper, the site selection index system of a landscape complementary power generation project is established by using the statistical methods and statistical analysis in the literature. Subsequently, using the Analytic Network Process to calculate the index weight, a cloud model was used in combination with preference ranking organization method for enrichment evaluations to transform and sort uncertain language information. Finally, using the results of the decision-making for the location of the Shanghai wind-solar complementary project and by carrying out contrast analysis and sensitivity analysis, the superiority and stability of the decision model constructed in this study was demonstrated.

  15. Selected Contributions of the 4th European Meeting on Solar Chemistry and Photocatalysis. Environmental Applications (SPEA 4)

    International Nuclear Information System (INIS)

    Malato Rodriguez, S.; Gernjak, W.; Pereze Pena, J.; Dona Rodriguez, J.M.

    2007-01-01

    In developed countries, the importance of water as a resource and problems derived from its scarcity has led to growing social and legislative demands. As a consequence, in the last 30 years, new fields of research have opened in a search for more efficient water treatment methods. This is the case of the advanced oxidation techniques (AOTs) and their application to nonbiodegradable contaminants, which can otherwise be removed from water, but not eliminated. Fast development of research in this field has encouraged chemists, chemical engineers and related professionals to meet and debate their findings and plan new strategies for the future, working toward evermore efficient methods of wastewater treatment wherever needed. The same can be said of gaseous effluents, as emission limits for organic air pollution become stricter. Volatile organic compounds (VOCs) pose an environmental and health threat, which can be treated by adsorption, incineration, condensation, etc., or be completely destroyed by chemical methods, such as the very promising gas-phase photocatalytic air pollution treatment. The SPEA Meetings have been held against this background, particularly this fourth one, where scientists assembled to present and debate their latest achievements in low-cost treatment technologies for wastewater, gaseous effluents and polluted soils. This Special Issue of Catalysis Today was compiled from the scientific reports generated by the congress, and includes a selection of some of the most interesting work presented at the meeting. The 34-member Scientific Committee were from 11 different countries (Argentina, Chile, Finland, France, Germany, Greece, Italy, Slovakia, Spain, Switzerland, and the USA). One hundred and thirty-five delegates from 22 different countries attended the congress (representing 368 authors). One hundred and thirty-eight communications were presented, 45 oral presentations and 93 posters. Three plenary lectures, one round table and two poster

  16. Standardized performance tests of collectors of solar thermal energy: A selectively coated, steel collector with one transparent cover

    Science.gov (United States)

    1976-01-01

    Basic test results are presented of a flat-plate solar collector whose performance was determined in solar simulator. The collector was tested over ranges of inlet temperatures, fluxes and coolant flow rates. Collector efficiency was correlated in terms of inlet temperature and flux level.

  17. Spectral Pollution

    OpenAIRE

    Davies, E B; Plum, M

    2003-01-01

    We discuss the problems arising when computing eigenvalues of self-adjoint operators which lie in a gap between two parts of the essential spectrum. Spectral pollution, i.e. the apparent existence of eigenvalues in numerical computations, when no such eigenvalues actually exist, is commonplace in problems arising in applied mathematics. We describe a geometrically inspired method which avoids this difficulty, and show that it yields the same results as an algorithm of Zimmermann and Mertins.

  18. Structural, morphological, and optical characterizations of Mo, CrN and Mo:CrN sputtered coatings for potential solar selective applications

    Science.gov (United States)

    Ibrahim, Khalil; Mahbubur Rahman, M.; Taha, Hatem; Mohammadpour, Ehsan; Zhou, Zhifeng; Yin, Chun-Yang; Nikoloski, Aleksandar; Jiang, Zhong-Tao

    2018-05-01

    Mo, CrN, and Mo:CrN sputtered coatings synthesized onto silicon Si(100) substrates were investigated as solar selective surfaces and their potential applications in optical devices. These coatings were characterized using XRD, SEM, UV-vis, and FTIR techniques. XRD investigation, showed a change in CrN thin film crystallite characteristic due to Mo doping. Compared to the CrN coating, the Mo:CrN film has a higher lattice parameter and lower grain size of 4.19 nm and 106.18 nm, respectively. FESEM morphology confirmed the decrement in Mo:CrN crystal size due to Mo doping. Optical analysis showed that in the visible range of the solar spectrum, the CrN coatings exhibit the highest solar absorptance of 66% while the lowest thermal emittance value of 5.67 was recorded for the CrN coating doped with Mo. Consequently, the highest solar selectivity of 9.6, and the energy band-gap of 2.88 eV were achieved with the Mo-doped CrN coatings. Various optical coefficients such as optical absorption coefficient, refractive index, extinction coefficient, real and imaginary parts of dielectric constants, and energy loss functions of these coatings were also estimated from the optical reflectance data recorded in the wavelength range of 190-2300 nm.

  19. Photon management in thin-film solar cells; Photon-Management in Duennschicht-Solarzellen

    Energy Technology Data Exchange (ETDEWEB)

    Fahr, Stephan

    2011-11-22

    In this thesis procedures were presented, which modify the propagation of the incident light in such a way that by this the efficiency of thin-film solar cells is increased. The strength of the presented numerical studies lies thereby in the rigorous solution of Maxwell's equations. Fundamental statements concerning the lay-out of an ideal texture could be made, which for present thin-film solar cells over the whole relevant spectral range both suppresses reflection losses and leads to an elongation of the effective path. Object of the thesis was also the design of a spectral- and angular-selective filter, which confines the acceptance angle of a solar cell with the aim of an improved absorption in the long-wave spectral region. Furthermore also tandem cells on the base of amorphous and microcrystalline silicon were studied.

  20. SOLAR EFFECTS ON BUILDING DESIGN.

    Science.gov (United States)

    Building Research Inst., Inc., Washington, DC.

    A REPORT OF A PROGRAM HELD AS PART OF THE BUILDING RESEARCH INSTITUTE 1962 SPRING CONFERENCE ON THE SOLAR EFFECTS ON BUILDING DESIGN. TOPICS DISCUSSED ARE--(1) SOLAR ENERGY DATA APPLICABLE TO BUILDING DESIGN, (2) THERMAL EFFECTS OF SOLAR RADIATION ON MAN, (3) SOLAR EFFECTS ON ARCHITECTURE, (4) SOLAR EFFECTS ON BUILDING COSTS, (5) SELECTION OF…

  1. SORCE: Solar Radiation and Climate Experiment

    Science.gov (United States)

    Cahalan, Robert; Rottman, Gary; Lau, William K. M. (Technical Monitor)

    2002-01-01

    Contents include the following: Understanding the Sun's influence on the Earth; How the Sun affect Earth's climate; By how much does the Sun's radiation very; Understanding Solar irradiance; History of Solar irradiance observations; The SORCE mission; How do the SORCE instruments measure solar radiation; Total irradiance monitor (TIM); Spectral irradiance monitor (SIM); Solar stellar irradiance comparison experiment (SOLSTICE); XUV photometer system (XPS).

  2. Models of Solar Irradiance Variations: Current Status

    Indian Academy of Sciences (India)

    2016-01-27

    Jan 27, 2016 ... Models of Solar Irradiance Variations: Current Status. Natalie A. ... Regular monitoring of solar irradiance has been carried out since 1978 to show that solar total and spectral irradiance varies at different time scales. Whereas ... Max Planck Institute for Solar System Research, Katlenburg-Lindau, Germany.

  3. Mechanical spectral shift reactor

    International Nuclear Information System (INIS)

    Wilson, J.F.; Sherwood, D.G.

    1982-01-01

    A mechanical spectral shift reactor comprises a reactive core having fuel assemblies accommodating both water displacer elements and neutron absorbing control rods for selectively changing the volume of water-moderator in the core. The fuel assemblies with displacer and control rods are arranged in alternating fashion so that one displacer element drive mechanism may move displacer elements in more than one fuel assembly without interfering with the movement of control rods of a corresponding control rod drive mechanisms. (author)

  4. Selection of groundwater sites in Egypt, using geographic information systems, for desalination by solar energy in order to reduce greenhouse gases

    Directory of Open Access Journals (Sweden)

    Mariam G. Salim

    2012-01-01

    Full Text Available Although Egypt has already reached the water poverty limit, it possesses a high potential of brackish groundwater available from different aquifers. All Arab countries lie in the best sun-belt region in the world and Egypt has the highest number of sun hours all year round. Solar energy for groundwater desalination is an independent infinite energy resource; it has low running costs and reduces the contribution of greenhouse gases (GHG to global warming. Perfect meteorological conditions and land space are available in remote areas, where solar desalination could supply freshwater for drinking, industry, and for greenhouse agriculture. The present study uses Geographic Information System(s (GIS as a spatial decision support tool to select appropriate sites in Egypt for groundwater solar desalination. Solar radiation, aquifer depth, aquifer salinity, distance from the Delta and the Nile Valley, incidence of flash floods, sand dunes, rock faults, and seawater intrusion in the North Delta, are the criteria that have been taken into consideration in the process of analysis. A specific weight is given to each criterion according to its relative influence on the process of decision making. The results from the application of the presented methodology determine the relative suitability of sites for groundwater solar desalination. These sites are ranked in descending order to help decision-makers in Egypt. The results show that groundwater solar desalination is suitable in remote regions on the North Western Coast, on the North Sinai Coast, and at the Southern Oasis, for reducing greenhouse gases and that it is particularly useful for poor communities suffering from polluted water.

  5. Nanoparticle-doped Polymer Foils for Use in Solar Control Glazing

    Science.gov (United States)

    Smith, G. B.; Deller, C. A.; Swift, P. D.; Gentle, A.; Garrett, P. D.; Fisher, W. K.

    2002-04-01

    Since nanoparticles can provide spectrally selective absorption without scattering they can be used to dope polymers for use in windows, to provide a clear view while strongly attenuating both solar heat gain and UV, at lower cost than alternative technologies. The underlying physics and how it influences the choice and concentration of nanoparticle materials is outlined. Spectral data, visible and solar transmittance, and solar heat gain coefficient are measured for clear polymers and some laminated glass, in which the polymer layer is doped with conducting oxide nanoparticles. Simple models are shown to apply making general optical design straightforward. Use with clear glass and tinted glass is considered and performance shown to match existing solar control alternatives. A potential for widespread adoption in buildings and cars is clearly demonstrated, and scopes for further improvements are identified, so that ultimately both cost and performance are superior.

  6. Nanoparticle-doped Polymer Foils for Use in Solar Control Glazing

    International Nuclear Information System (INIS)

    Smith, G.B.; Deller, C.A.; Swift, P.D.; Gentle, A.; Garrett, P.D.; Fisher, W.K.

    2002-01-01

    Since nanoparticles can provide spectrally selective absorption without scattering they can be used to dope polymers for use in windows, to provide a clear view while strongly attenuating both solar heat gain and UV, at lower cost than alternative technologies. The underlying physics and how it influences the choice and concentration of nanoparticle materials is outlined. Spectral data, visible and solar transmittance, and solar heat gain coefficient are measured for clear polymers and some laminated glass, in which the polymer layer is doped with conducting oxide nanoparticles. Simple models are shown to apply making general optical design straightforward. Use with clear glass and tinted glass is considered and performance shown to match existing solar control alternatives. A potential for widespread adoption in buildings and cars is clearly demonstrated, and scopes for further improvements are identified, so that ultimately both cost and performance are superior

  7. Frequency agile solar radiotelescope

    Science.gov (United States)

    Bastian, Tim S.

    2003-02-01

    The Frequency Agile Solar Radiotelescope (FASR) is a solar-dedicated, ground based, interferometric array optimized to perform broadband imaging spectroscopy from ~ 0.1-30+ GHz. It will do so with the angular, spectral, and temporal resolution required to exploit radio emission from the Sun as a diagnostic of the wide variety of astrophysical processes that occur there. FASR represents a major advance over existing radioheliographs, and is expected to remain the world's premier solar radio instrument for two decades or more after completion. FASR will be a versatile and powerful instrument, providing unique data to a broad users community. Solar, solar-terrestrial, and space physicists will exploit FASR to attack a broad science program, including problems of fundamental interest: coronal magnetography, solar flares and particle acceleration, drivers of space weather, and the thermal structure and dynamics of the solar atmosphere. A design study and implementation planning are underway. Recent progress is reviewed here.

  8. Solar radiation absorbing material

    Science.gov (United States)

    Googin, John M.; Schmitt, Charles R.; Schreyer, James M.; Whitehead, Harlan D.

    1977-01-01

    Solar energy absorbing means in solar collectors are provided by a solar selective carbon surface. A solar selective carbon surface is a microporous carbon surface having pores within the range of 0.2 to 2 micrometers. Such a surface is provided in a microporous carbon article by controlling the pore size. A thermally conductive substrate is provided with a solar selective surface by adhering an array of carbon particles in a suitable binder to the substrate, a majority of said particles having diameters within the range of about 0.2-10 microns.

  9. Calibration of EOS multispectral imaging sensors and solar irradiance variability

    Science.gov (United States)

    Mecherikunnel, Ann

    1991-01-01

    Earth Observation System (EOS) optical multispectral imaging sensors provide images of the earth at various spectral and spatial resolutions, in the visible (VIS) and infrared (IR) regions of the solar spectrum. Accurate knowledge of extraterrestrial solar spectral irradiance and its variations with time, are needed to trace sensor calibration in space, and for the development of terrestrial atmospheric models needed in data validation. A brief review of the extraterrestrial solar VIS/IR spectral irradiance available in the literature will be reviewed, and the need to develop an extraterrestrial solar spectral irradiance for the EOS studies will be pointed out. The solar calibration of the Earth Radiation Budget Experiments (ERBE), earth-viewing sensors will be discussed. Observed variations in the solar constant (solar irradiance, at the mean sun-earth distance of one astronomical unit, integrated over all wavelengths), and solar spectral irradiance with solar activity and its implications for EOS studies also will be discussed.

  10. Quantitative Analysis of Spectral Impacts on Silicon Photodiode Radiometers: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Myers, D. R.

    2011-04-01

    Inexpensive broadband pyranometers with silicon photodiode detectors have a non-uniform spectral response over the spectral range of 300-1100 nm. The response region includes only about 70% to 75% of the total energy in the terrestrial solar spectral distribution from 300 nm to 4000 nm. The solar spectrum constantly changes with solar position and atmospheric conditions. Relative spectral distributions of diffuse hemispherical irradiance sky radiation and total global hemispherical irradiance are drastically different. This analysis convolves a typical photodiode response with SMARTS 2.9.5 spectral model spectra for different sites and atmospheric conditions. Differences in solar component spectra lead to differences on the order of 2% in global hemispherical and 5% or more in diffuse hemispherical irradiances from silicon radiometers. The result is that errors of more than 7% can occur in the computation of direct normal irradiance from global hemispherical irradiance and diffuse hemispherical irradiance using these radiometers.

  11. The use of wavelength-selective plastic cladding materials in horticulture: understanding of crop and fungal responses through the assessment of biological spectral weighting functions.

    Science.gov (United States)

    Paul, Nigel D; Jacobson, Rob J; Taylor, Anna; Wargent, Jason J; Moore, Jason P

    2005-01-01

    Plant responses to light spectral quality can be exploited to deliver a range of agronomically desirable end points in protected crops. This can be achieved using plastics with specific spectral properties as crop covers. We have studied the responses of a range of crops to plastics that have either (a) increased transmission of UV compared with standard horticultural covers, (b) decreased transmission of UV or (c) increased the ratio of red (R) : far-red (FR) radiation. Both the UV-transparent and R : FR increasing films reduced leaf area and biomass, offering potential alternatives to chemical growth regulators. The UV-opaque film increased growth, but while this may be useful in some crops, there were trade-offs with elements of quality, such as pigmentation and taste. UV manipulation may also influence disease control. Increasing UV inhibited not only the pathogenic fungus Botrytis cinerea but also the disease biocontrol agent Trichoderma harzianum. Unlike B. cinerea, T. harzianum was highly sensitive to UV-A radiation. These fungal responses and those for plant growth in the growth room and the field under different plastics are analyzed in terms of alternative biological spectral weighting functions (BSWF). The role of BSWF in assessing general patterns of response to UV modification in horticulture is also discussed.

  12. Solar-Driven Reduction of Aqueous Protons Coupled to Selective Alcohol Oxidation with a Carbon Nitride-Molecular Ni Catalyst System.

    Science.gov (United States)

    Kasap, Hatice; Caputo, Christine A; Martindale, Benjamin C M; Godin, Robert; Lau, Vincent Wing-Hei; Lotsch, Bettina V; Durrant, James R; Reisner, Erwin

    2016-07-27

    Solar water-splitting represents an important strategy toward production of the storable and renewable fuel hydrogen. The water oxidation half-reaction typically proceeds with poor efficiency and produces the unprofitable and often damaging product, O2. Herein, we demonstrate an alternative approach and couple solar H2 generation with value-added organic substrate oxidation. Solar irradiation of a cyanamide surface-functionalized melon-type carbon nitride ((NCN)CNx) and a molecular nickel(II) bis(diphosphine) H2-evolution catalyst (NiP) enabled the production of H2 with concomitant selective oxidation of benzylic alcohols to aldehydes in high yield under purely aqueous conditions, at room temperature and ambient pressure. This one-pot system maintained its activity over 24 h, generating products in 1:1 stoichiometry, separated in the gas and solution phases. The (NCN)CNx-NiP system showed an activity of 763 μmol (g CNx)(-1) h(-1) toward H2 and aldehyde production, a Ni-based turnover frequency of 76 h(-1), and an external quantum efficiency of 15% (λ = 360 ± 10 nm). This precious metal-free and nontoxic photocatalytic system displays better performance than an analogous system containing platinum instead of NiP. Transient absorption spectroscopy revealed that the photoactivity of (NCN)CNx is due to efficient substrate oxidation of the material, which outweighs possible charge recombination compared to the nonfunctionalized melon-type carbon nitride. Photoexcited (NCN)CNx in the presence of an organic substrate can accumulate ultralong-lived "trapped electrons", which allow for fuel generation in the dark. The artificial photosynthetic system thereby catalyzes a closed redox cycle showing 100% atom economy and generates two value-added products, a solar chemical, and solar fuel.

  13. [Hygiene and the spectral energtic light pattern].

    Science.gov (United States)

    Kaptsov, V A; Deynego, V N; SoshMn, N P; Ulasyuk, V N

    There are considered methodological bases of multicriteria synthesis of a spectral energetic pattern for the evaluation of the excessive share of blue and red light in the spectrum of artificial energy sources. The basis of this methodology is relied upon on the hygienic approach to the spectrum analysis of solar and led light. Relying upon on "photobiological paradox of vision" according to M. A. Ostrovsky, conditions of "melanopsin cross" and mechanisms of adverse impact of light on vision, all the spectral-energy characteristics of solar light were divided into subspaces. The border between them became a spectral energy pattern for the evaluation of artificial sources on the security of their impact on eye and human health according to criteria of the excessive dose of blue or red light. On two examples there was shown the effectiveness and clarity of this estimation with the using of the spectral energetic pattern of light.

  14. Carbon-in-silica composite selective solar absorbers: a determination of composition and dielectic properties - SAIP Poster

    CSIR Research Space (South Africa)

    Katumba, G

    2006-07-01

    Full Text Available of the spectral den- sity given by: ? ? ? ? 3 1 , a n d ,1), 1 0 1 0 f d nfnn gd nfng −==? ? The microstructure of the samples was studied by cross-sectional high resolution transmission elec- tron microscopy (X-HRTEM). A...

  15. Optimal site selection for sitting a solar park using multi-criteria decision analysis and geographical information systems

    Science.gov (United States)

    Georgiou, Andreas; Skarlatos, Dimitrios

    2016-07-01

    Among the renewable power sources, solar power is rapidly becoming popular because it is inexhaustible, clean, and dependable. It has also become more efficient since the power conversion efficiency of photovoltaic solar cells has increased. Following these trends, solar power will become more affordable in years to come and considerable investments are to be expected. Despite the size of solar plants, the sitting procedure is a crucial factor for their efficiency and financial viability. Many aspects influence such a decision: legal, environmental, technical, and financial to name a few. This paper describes a general integrated framework to evaluate land suitability for the optimal placement of photovoltaic solar power plants, which is based on a combination of a geographic information system (GIS), remote sensing techniques, and multi-criteria decision-making methods. An application of the proposed framework for the Limassol district in Cyprus is further illustrated. The combination of a GIS and multi-criteria methods produces an excellent analysis tool that creates an extensive database of spatial and non-spatial data, which will be used to simplify problems as well as solve and promote the use of multiple criteria. A set of environmental, economic, social, and technical constrains, based on recent Cypriot legislation, European's Union policies, and expert advice, identifies the potential sites for solar park installation. The pairwise comparison method in the context of the analytic hierarchy process (AHP) is applied to estimate the criteria weights in order to establish their relative importance in site evaluation. In addition, four different methods to combine information layers and check their sensitivity were used. The first considered all the criteria as being equally important and assigned them equal weight, whereas the others grouped the criteria and graded them according to their objective perceived importance. The overall suitability of the study

  16. Intensity Conserving Spectral Fitting

    Science.gov (United States)

    Klimchuk, J. A.; Patsourakos, S.; Tripathi, D.

    2015-01-01

    The detailed shapes of spectral line profiles provide valuable information about the emitting plasma, especially when the plasma contains an unresolved mixture of velocities, temperatures, and densities. As a result of finite spectral resolution, the intensity measured by a spectrometer is the average intensity across a wavelength bin of non-zero size. It is assigned to the wavelength position at the center of the bin. However, the actual intensity at that discrete position will be different if the profile is curved, as it invariably is. Standard fitting routines (spline, Gaussian, etc.) do not account for this difference, and this can result in significant errors when making sensitive measurements. Detection of asymmetries in solar coronal emission lines is one example. Removal of line blends is another. We have developed an iterative procedure that corrects for this effect. It can be used with any fitting function, but we employ a cubic spline in a new analysis routine called Intensity Conserving Spline Interpolation (ICSI). As the name implies, it conserves the observed intensity within each wavelength bin, which ordinary fits do not. Given the rapid convergence, speed of computation, and ease of use, we suggest that ICSI be made a standard component of the processing pipeline for spectroscopic data.

  17. ISSSR Tutorial 1: Introduction to Spectral Remote Sensing

    Science.gov (United States)

    1994-08-01

    frequencies can undergo conversion to thermal energy, a process of broad-band absorption, as in solar heating of the earth, solar cookers , and...but show 14 wb-match in its reflected solar spectral signature. 2. RADIATION - THE CARRIER OF INFORMATION 2.1 BASIC CHARACTERISTICS Until 1819...thermal infrared domain and the need for different types of detectors. Although there is stili a solar component, the amount is small eompared to the 0A

  18. Formation of double-layered TiO2 structures with selectively-positioned molecular dyes for efficient flexible dye-sensitized solar cells

    International Nuclear Information System (INIS)

    Kim, Eun Yi; Yu, Sora; Moon, Jeong Hoon; Yoo, Seon Mi; Kim, Chulhee; Kim, Hwan Kyu; Lee, Wan In

    2013-01-01

    Graphical abstract: A novel flexible tandem dye-sensitized solar cell, selectively loading different dyes in discrete layers, was successfully formed on a plastic substrate by transferring the high-temperature-processed N719/TiO 2 over an organic dye-adsorbed TiO 2 film by a typical compression process at room temperature. -- Highlights: • A novel flexible dye-sensitized solar cell, selectively loading two different dyes in discrete layers, was successfully formed on a plastic substrate. • η of the flexible tandem cell obtained by transferring the high-temperature-processed TiO 2 layer was enhanced from 2.91% to 6.86%. • Interface control between two TiO 2 layers is crucial for the efficient transport of photo-injected electrons from the top to bottom TiO 2 layer. -- Abstract: To fabricate flexible dye-sensitized solar cells (DSCs) utilizing full solar spectrum, the double-layered TiO 2 films, selectively loading two different dyes in discrete layers, were formed on a plastic substrate by transferring the high-temperature-processed N719/TiO 2 over an organic dye (TA-St-CA)-sensitized TiO 2 film by a typical compression process at room temperature. It was found that interface control between two TiO 2 layers is crucial for the efficient transport of photo-injected electrons from the N719/TiO 2 to the TA-St-CA/TiO 2 layer. Electron impedance spectra (EIS) and transient photoelectron spectroscopic analyses exhibited that introduction of a thin interfacial TiO 2 layer between the two TiO 2 layers remarkably decreased the resistance at the interface, while increasing the electron diffusion constant (D e ) by ∼10 times. As a result, the photovoltaic conversion efficiency (η) of the flexible tandem DSC was 6.64%, whereas that of the flexible cell derived from the single TA-St-CA/TiO 2 layer was only 2.98%. Another organic dye (HC-acid), absorbing a short wavelength region of solar spectrum, was also applied to fabricate flexible tandem DSC. The η of the cell

  19. Solar-simulated ultraviolet irradiation induces selective influx of CD4+ T lymphocytes in normal human skin

    NARCIS (Netherlands)

    Di Nuzzo, S.; de Rie, M. A.; van der Loos, C. M.; Bos, J. D.; Teunissen, M. B.

    1996-01-01

    The proportion and composition of the human cutaneous CD3+ T lymphocyte population was determined in situ following a single exposure to physiological, erythema-inducing doses of simulated solar radiation, mainly consisting of UV radiation. Biopsies were taken 1, 2 and 7 days after local irradiation

  20. "Calibration" system for spectral measurements and its experimental results

    Science.gov (United States)

    Bruchkouskaya, Sviatlana I.; Katkovsky, Leonid V.; Belyaev, Boris I.; Malyshev, Vladislav B.

    2017-04-01

    "Calibration" system has been developed at A. N. Sevchenko Research Institute of Applied Physical Problems of the Belarusian State University. It was designed for measuring the characteristics of spectral reflectance of all types of natural surfaces (test sites) in ground conditions or on board of aircraft carriers and has the following components: - Photospectroradiometr (PhSR) of high resolution with a range of 400-900 nm, equipped with a digital time-lapse video system; - Two-channel modular spectroradiometer (TMS) with a range of 400-900 nm, designed for simultaneous measurements of reflected light brightness of the underlying surface and the incident radiation from the upper hemisphere; - Two portable spectroradiometers (PSR-700 and PSR-1300) with a spectral range 800-1500 nm; 1200-2500 nm; - Scanning solar spectropolarimeter (SSP-600) with a range of 350-950 nm for measurements of direct sunlight and scattered by the atmosphere at different angles; "Calibration" system provides spectral resolution of 5.2 nm in a range of 400-900 nm, 10 nm in a range of 800-1500 nm and 15 nm in a range of 1200-2500 nm. Measurements of the optical characteristics of solar radiation (for determining parameters of the atmosphere) and that of underlying surface are synchronous. There is also a set of special nozzles for measurements of spectral brightness coefficients, polarization characteristics and spectral albedo. Spectra and images are geotagged to the navigation data (time, GPS). For the measurements of spectral reflection dependencies within "Monitoring-SG" framework expeditions to the Kuril Islands, Kursk aerospace test site and Kamchatka Peninsula were conducted in 2015 and 2016. The spectra of different underlying surfaces have been obtained: soils, plants and water objects, sedimentary and volcanic rocks. These surveys are a valuable material for further researches and selection of test facilities for flight calibration of space imaging systems. Information obtained

  1. Correlation Feature Selection and Mutual Information Theory Based Quantitative Research on Meteorological Impact Factors of Module Temperature for Solar Photovoltaic Systems

    Directory of Open Access Journals (Sweden)

    Yujing Sun

    2016-12-01

    Full Text Available The module temperature is the most important parameter influencing the output power of solar photovoltaic (PV systems, aside from solar irradiance. In this paper, we focus on the interdisciplinary research that combines the correlation analysis, mutual information (MI and heat transfer theory, which aims to figure out the correlative relations between different meteorological impact factors (MIFs and PV module temperature from both quality and quantitative aspects. The identification and confirmation of primary MIFs of PV module temperature are investigated as the first step of this research from the perspective of physical meaning and mathematical analysis about electrical performance and thermal characteristic of PV modules based on PV effect and heat transfer theory. Furthermore, the quantitative description of the MIFs influence on PV module temperature is mathematically formulated as several indexes using correlation-based feature selection (CFS and MI theory to explore the specific impact degrees under four different typical weather statuses named general weather classes (GWCs. Case studies for the proposed methods were conducted using actual measurement data of a 500 kW grid-connected solar PV plant in China. The results not only verified the knowledge about the main MIFs of PV module temperatures, more importantly, but also provide the specific ratio of quantitative impact degrees of these three MIFs respectively through CFS and MI based measures under four different GWCs.

  2. Spectral Unmixing With Multiple Dictionaries

    Science.gov (United States)

    Cohen, Jeremy E.; Gillis, Nicolas

    2018-02-01

    Spectral unmixing aims at recovering the spectral signatures of materials, called endmembers, mixed in a hyperspectral or multispectral image, along with their abundances. A typical assumption is that the image contains one pure pixel per endmember, in which case spectral unmixing reduces to identifying these pixels. Many fully automated methods have been proposed in recent years, but little work has been done to allow users to select areas where pure pixels are present manually or using a segmentation algorithm. Additionally, in a non-blind approach, several spectral libraries may be available rather than a single one, with a fixed number (or an upper or lower bound) of endmembers to chose from each. In this paper, we propose a multiple-dictionary constrained low-rank matrix approximation model that address these two problems. We propose an algorithm to compute this model, dubbed M2PALS, and its performance is discussed on both synthetic and real hyperspectral images.

  3. Selection of astrophysical/astronomical/solar sites at the Argentina East Andes range taking into account atmospheric components

    Czech Academy of Sciences Publication Activity Database

    Piacentini, R.D.; García, B.; Micheletti, M.I.; Salum, G.; Freire, M.; Maya, J.; Mancilla, A.; Crinó, E.; Mandát, Dušan; Pech, M.; Bulik, T.

    2016-01-01

    Roč. 57, č. 12 (2016), s. 2559-2574 ISSN 0273-1177 R&D Projects: GA MŠk(CZ) 7AMB14AR005; GA MŠk LE13012; GA MŠk LG14019; GA MŠk LM2015046 Institutional support: RVO:68378271 Keywords : astrophysical * astronomical * solar: sites * Argentina-Andes: atmospheric components Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics Impact factor: 1.401, year: 2016

  4. Performance of spectral fitting methods for vegetation fluorescence quantification

    NARCIS (Netherlands)

    Meroni, M.; Busetto, D.; Colombo, R.; Guanter, L.; Moreno, J.; Verhoef, W.

    2010-01-01

    The Fraunhofer Line Discriminator (FLD) principle has long been considered as the reference method to quantify solar-induced chlorophyll fluorescence (F) from passive remote sensing measurements. Recently, alternative retrieval algorithms based on the spectral fitting of hyperspectral radiance

  5. Evaluation of intensity and energy interaction parameters for the complexation of Pr(III) with selected nucleoside and nucleotide through absorption spectral studies

    Science.gov (United States)

    Bendangsenla, N.; Moaienla, T.; David Singh, Th.; Sumitra, Ch.; Rajmuhon Singh, N.; Indira Devi, M.

    2013-02-01

    The interactions of Pr(III) with nucleosides and nucleotides have been studied in different organic solvents employing absorption difference and comparative absorption spectrophotometry. The magnitudes of the variations in both energy and intensity interaction parameters were used to explore the degree of outer and inner sphere co-ordination, incidence of covalency and the extent of metal 4f-orbital involvement in chemical bonding. Various electronic spectral parameters like Slater-Condon (Fk), Racah (Ek), Lande parameter (ξ4f), Nephelauxatic ratio (β), bonding (b1/2), percentage covalency (δ) and intensity parameters like oscillator strength (P) and Judd Ofelt electronic dipole intensity parameter (Tλ, λ = 2, 4, 6) have been evaluated. The variation of these evaluated parameters were employed to interpret the nature of binding of Pr(III) with different ligands i.e. Adenosine/ATP in presence and absence of Ca2+.

  6. Sensitivity of constrained linear inversions to the selection of the Lagrange multiplier. [for inferring columnar aerosol size distribution from spectral aerosol optical depth measurements

    Science.gov (United States)

    King, M. D.

    1982-01-01

    The influence of the choice of the Lagrange multiplier on constrained linear inversions is explored, with reference made to applications in inferring the columnar aerosol size distributions from spectral aerosol optical depth measurements. A range of the Lagrange multiplier is examined to find all positive solutions for the solution vector, which represents modifying factors to the assumed form of the size distribution. An iterative method is devised to constrain the calculations to consideration of only positive quantities and a requirement that the regression fit to data be consistent with measurement errors. The determination of the variances and covariances is formulated and applied to existing data sets for optical depth. Variances in the solution are found to be large for particle radii when the information content of the data is small.

  7. Intercomparison of spectral irradiance measurements and provision of alternative radiation scheme for CCMs of middle atmosphere

    Science.gov (United States)

    Pagaran, Joseph; Weber, Mark; Burrows, John P.

    The Sun's radiative output (total solar irradiance or TSI) determines the thermal structure of the Earth's atmosphere. Its variability is a strong function of wavelength, which drives the photochemistry and general circulation. Contributions to TSI variability from UV wavelengths below 400 nm, i.e. 0.227-day solar rotation or 0.1to be in the 40-60three decades of UV and about a decade of vis-IR observations. Significant progress in UV/vis-IR regions has been achieved with daily monitoring from SCIAMACHY aboard Envisat (ESA) in 2002 and by SIM aboard SORCE (NASA) about a year after. In this contribution, we intercompare SSI measurements from SCIAMACHY and SIM and RGB filters of SPM/VIRGO SoHO: same (a) day and (b) few 27-day time series of spectral measurements in both irradiance and integrated irradiance over selected wavelength intervals. Finally, we show how SSI measurements from GOME, SOLSTICE, in addition to SCIAMACHY and SIM, can be modeled together with solar proxies F10.7 cm, Mg II and sunspot index (PSI) to derive daily SSI variability in the period 1947-2008. The derived variabilities are currently being used as solar input to Bremen's 3D-CTM and are to be recommended as extended alternative to Berlin's FUBRaD radiation scheme. This proxy-based radiation scheme are compared with SATIRE, NRLSSI (or Lean et al.), SUSIM, SSAI (or DeLand et al), and SIP (or Solar2000) models. The use of realistic spectrally resolved solar input to CCMs is to better understand the effects of solar variability on chemistry and temperature in the middle atmosphere over several decades.

  8. Spectral Decomposition Algorithm (SDA)

    Data.gov (United States)

    National Aeronautics and Space Administration — Spectral Decomposition Algorithm (SDA) is an unsupervised feature extraction technique similar to PCA that was developed to better distinguish spectral features in...

  9. Metamaterial Receivers for High Efficiency Concentrated Solar Energy Conversion

    Energy Technology Data Exchange (ETDEWEB)

    Yellowhair, Julius E. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Concentrating Solar Technologies Dept.; Kwon, Hoyeong [Univ. of Texas, Austin, TX (United States). Dept. of Electrical and Computer Engineering; Alu, Andrea [Univ. of Texas, Austin, TX (United States). Dept. of Electrical and Computer Engineering; Jarecki, Robert L. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Concentrating Solar Technologies Dept.; Shinde, Subhash L. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Concentrating Solar Technologies Dept.

    2016-09-01

    Operation of concentrated solar power receivers at higher temperatures (>700°C) would enable supercritical carbon dioxide (sCO2) power cycles for improved power cycle efficiencies (>50%) and cost-effective solar thermal power. Unfortunately, radiative losses at higher temperatures in conventional receivers can negatively impact the system efficiency gains. One approach to improve receiver thermal efficiency is to utilize selective coatings that enhance absorption across the visible solar spectrum while minimizing emission in the infrared to reduce radiative losses. Existing coatings, however, tend to degrade rapidly at elevated temperatures. In this report, we report on the initial designs and fabrication of spectrally selective metamaterial-based absorbers for high-temperature, high-thermal flux environments important for solarized sCO2 power cycles. Metamaterials are structured media whose optical properties are determined by sub-wavelength structural features instead of bulk material properties, providing unique solutions by decoupling the optical absorption spectrum from thermal stability requirements. The key enabling innovative concept proposed is the use of structured surfaces with spectral responses that can be tailored to optimize the absorption and retention of solar energy for a given temperature range. In this initial study through the Academic Alliance partnership with University of Texas at Austin, we use Tungsten for its stability in expected harsh environments, compatibility with microfabrication techniques, and required optical performance. Our goal is to tailor the optical properties for high (near unity) absorptivity across the majority of the solar spectrum and over a broad range of incidence angles, and at the same time achieve negligible absorptivity in the near infrared to optimize the energy absorbed and retained. To this goal, we apply the recently developed concept of plasmonic Brewster angle to suitably designed

  10. Highly selective transformation of ammonia nitrogen to N2 based on a novel solar-driven photoelectrocatalytic-chlorine radical reactions system.

    Science.gov (United States)

    Ji, Youzhi; Bai, Jing; Li, Jinhua; Luo, Tao; Qiao, Li; Zeng, Qingyi; Zhou, Baoxue

    2017-11-15

    A highly selective method for transforming ammonia nitrogen to N 2 was proposed, based on a novel solar-driven photoelectrocatalytic-chlorine radical reactions (PEC-chlorine) system. The PEC-chlorine system was facilitated by a visible light response WO 3 nanoplate array (NPA) electrode in an ammonia solution containing chloride ions (Cl - ). Under illumination, photoholes from WO 3 promote the oxidation of Cl - to chlorine radical (Cl). This radical can selectively transform ammonia nitrogen to N 2 (79.9%) and NO 3 - (19.2%), similar to the breakpoint chlorination reaction. The ammonia nitrogen removal efficiency increased from 10.6% (PEC without Cl - ) to 99.9% with the PEC-chlorine system within 90 min operation, which can be attributed to the cyclic reactions between Cl - /Cl and the reaction intermediates (NH 2 , NHCl, etc.) that expand the degradation reactions from the surface of the electrodes to the whole solution system. Moreover, Cl is the main radical species contributing to the transformation of ammonia nitrogen to N 2 , which is confirmed by the tBuOH capture experiment. Compared to conventional breakpoint chlorination, the PEC-chlorine system is a more economical and efficient means for ammonia nitrogen degradation because of the fast removal rate, no additional chlorine cost, and its use of clean energy (since it is solar-driven). Copyright © 2017 Elsevier Ltd. All rights reserved.

  11. InterTechnology Corporation technology summary, solar heating and cooling. National Solar Demonstration Program

    Energy Technology Data Exchange (ETDEWEB)

    None

    1976-12-01

    A summary of systems technology for solar-thermal heating and cooling of buildings is given. Solar collectors, control systems for solar heating and cooling, selective surfaces, thermal energy storage, solar-assisted heat pumps, and solar-powered cooling systems are discussed in detail. Also, an ITC specification for a solar control system is included. (WHK)

  12. Spectral splitting for thermal management in photovoltaic cells

    Science.gov (United States)

    Apostoleris, Harry; Chiou, Yu-Cheng; Chiesa, Matteo; Almansouri, Ibraheem

    2017-09-01

    Spectral splitting is widely employed as a way to divide light between different solar cells or processes to optimize energy conversion. Well-understood but less explored is the use of spectrum splitting or filtering to combat solar cell heating. This has impacts both on cell performance and on the surrounding environment. In this manuscript we explore the design of spectral filtering systems that can improve the thermal and power-conversion performance of commercial PV modules.

  13. Precision spectroscopy with a frequency-comb-calibrated solar spectrograph

    Science.gov (United States)

    Doerr, H.-P.

    2015-06-01

    precision spectroscopy of the Sun and laboratory light sources. The first scientific observations aimed at measuring the accurate wavelengths of selected solar Fraunhofer lines to characterise the so-called convective blue shift and its centre to limb variation. The convective blueshifts were derived with respect to laboratory wavelengths that were obtained from spectral lamps measured with the same instrument. The measurements agree with previous studies but provide a way higher accuracy. The data is only partially compatible with numerical simulations that were published recently. Further measurements were carried out to provide the absolute wavelengths of telluric O2 lines that are commonly used for wavelength calibration. With an accuracy of 1 m/s, these new measurements are two orders of magnitude better than existing data.

  14. Low-Cost Spectral Sensor Development Description.

    Energy Technology Data Exchange (ETDEWEB)

    Armijo, Kenneth Miguel; Yellowhair, Julius

    2014-11-01

    Solar spectral data for all parts of the US is limited due in part to the high cost of commercial spectrometers. Solar spectral information is necessary for accurate photovoltaic (PV) performance forecasting, especially for large utility-scale PV installations. A low-cost solar spectral sensor would address the obstacles and needs. In this report, a novel low-cost, discrete- band sensor device, comprised of five narrow-band sensors, is described. The hardware is comprised of commercial-off-the-shelf components to keep the cost low. Data processing algorithms were developed and are being refined for robustness. PV module short-circuit current ( I sc ) prediction methods were developed based on interaction-terms regression methodology and spectrum reconstruction methodology for computing I sc . The results suggest the computed spectrum using the reconstruction method agreed well with the measured spectrum from the wide-band spectrometer (RMS error of 38.2 W/m 2 -nm). Further analysis of computed I sc found a close correspondence of 0.05 A RMS error. The goal is for ubiquitous adoption of the low-cost spectral sensor in solar PV and other applications such as weather forecasting.

  15. Spectral Imaging by Upconversion

    DEFF Research Database (Denmark)

    Dam, Jeppe Seidelin; Pedersen, Christian; Tidemand-Lichtenberg, Peter

    2011-01-01

    We present a method to obtain spectrally resolved images using upconversion. By this method an image is spectrally shifted from one spectral region to another wavelength. Since the process is spectrally sensitive it allows for a tailored spectral response. We believe this will allow standard sili...... silicon based cameras designed for visible/near infrared radiation to be used for spectral images in the mid infrared. This can lead to much lower costs for such imaging devices, and a better performance.......We present a method to obtain spectrally resolved images using upconversion. By this method an image is spectrally shifted from one spectral region to another wavelength. Since the process is spectrally sensitive it allows for a tailored spectral response. We believe this will allow standard...

  16. Silicon-Rich Silicon Carbide Hole-Selective Rear Contacts for Crystalline-Silicon-Based Solar Cells.

    Science.gov (United States)

    Nogay, Gizem; Stuckelberger, Josua; Wyss, Philippe; Jeangros, Quentin; Allebé, Christophe; Niquille, Xavier; Debrot, Fabien; Despeisse, Matthieu; Haug, Franz-Josef; Löper, Philipp; Ballif, Christophe

    2016-12-28

    The use of passivating contacts compatible with typical homojunction thermal processes is one of the most promising approaches to realizing high-efficiency silicon solar cells. In this work, we investigate an alternative rear-passivating contact targeting facile implementation to industrial p-type solar cells. The contact structure consists of a chemically grown thin silicon oxide layer, which is capped with a boron-doped silicon-rich silicon carbide [SiC x (p)] layer and then annealed at 800-900 °C. Transmission electron microscopy reveals that the thin chemical oxide layer disappears upon thermal annealing up to 900 °C, leading to degraded surface passivation. We interpret this in terms of a chemical reaction between carbon atoms in the SiC x (p) layer and the adjacent chemical oxide layer. To prevent this reaction, an intrinsic silicon interlayer was introduced between the chemical oxide and the SiC x (p) layer. We show that this intrinsic silicon interlayer is beneficial for surface passivation. Optimized passivation is obtained with a 10-nm-thick intrinsic silicon interlayer, yielding an emitter saturation current density of 17 fA cm -2 on p-type wafers, which translates into an implied open-circuit voltage of 708 mV. The potential of the developed contact at the rear side is further investigated by realizing a proof-of-concept hybrid solar cell, featuring a heterojunction front-side contact made of intrinsic amorphous silicon and phosphorus-doped amorphous silicon. Even though the presented cells are limited by front-side reflection and front-side parasitic absorption, the obtained cell with a V oc of 694.7 mV, a FF of 79.1%, and an efficiency of 20.44% demonstrates the potential of the p + /p-wafer full-side-passivated rear-side scheme shown here.

  17. Solar Wind Variation with the Cycle

    Indian Academy of Sciences (India)

    2016-01-27

    Jan 27, 2016 ... The average solar wind density, velocity and temperature measured at the Earth's orbit show specific decadal variations and trends, which are of the order of the first tens per cent during the last three solar cycles. Statistical, spectral and correlation characteristics of the solar wind are reviewed with the ...

  18. Novel Receiver-Enhanced Solar Vapor Generation: Review and Perspectives

    Directory of Open Access Journals (Sweden)

    Aikifa Raza

    2018-01-01

    Full Text Available Efficient solar vapor/steam generation is important for various applications ranging from power generation, cooling, desalination systems to compact and portable devices like drinking water purification and sterilization units. However, conventional solar steam generation techniques usually rely on costly and cumbersome optical concentration systems and have relatively low efficiency due to bulk heating of the entire liquid volume. Recently, by incorporating novel light harvesting receivers, a new class of solar steam generation systems has emerged with high vapor generation efficiency. They are categorized in two research streams: volumetric and floating solar receivers. In this paper, we review the basic principles of these solar receivers, the mechanism involving from light absorption to the vapor generation, and the associated challenges. We also highlight the two routes to produce high temperature steam using optical and thermal concentration. Finally, we propose a scalable approach to efficiently harvest solar energy using a semi-spectrally selective absorber with near-perfect visible light absorption and low thermal emittance. Our proposed approach represents a new development in thermally concentrated solar distillation systems, which is also cost-effective and easy to fabricate for rapid industrial deployment.

  19. Solar Indices - Solar Irradiance

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Collection includes a variety of indices related to solar activity contributed by a number of national and private solar observatories located worldwide. This...

  20. Solar Indices - Solar Ultraviolet

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Collection includes a variety of indices related to solar activity contributed by a number of national and private solar observatories located worldwide. This...

  1. Solar Indices - Solar Corona

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Collection includes a variety of indices related to solar activity contributed by a number of national and private solar observatories located worldwide. This...

  2. Solar Indices - Solar Flares

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Collection includes a variety of indices related to solar activity contributed by a number of national and private solar observatories located worldwide. This...

  3. Cost analysis of an air Brayton receiver for a solar thermal electric power system in selected annual production volumes

    Science.gov (United States)

    1981-12-01

    Pioneer Engineering and Manufacturing Company estimated the cost of manufacturing and Air Brayton Receiver for a Solar Thermal Electric Power System as designed by the AiResearch Division of the Garrett Corporation. Production costs were estimated at annual volumes of 100; 1,000; 5,000; 10,000; 50,000; 100,000 and 1,000,000 units. These costs included direct labor, direct material and manufacturing burden. A make or buy analysis was made of each part of each volume. At high volumes special fabrication concepts were used to reduce operation cycle times. All costs were estimated at an assumed 100% plant capacity. Economic feasibility determined the level of production at which special concepts were to be introduced. Estimated costs were based on the economics of the last half of 1980. Tooling and capital equipment costs were estimated for ach volume. Infrastructure and personnel requirements were also estimated.

  4. Site selective doping of Zn for the p-type Cu(In,Ga)Se{sub 2} thin film for solar cell application

    Energy Technology Data Exchange (ETDEWEB)

    Shirakata, Sho [Faculty of Engineering, Ehime University, Matsuyama 790-8577 (Japan); Tokyo University of Science, Research Institute for Science and Technology, Noda, Chiba 278-8510 (Japan)

    2017-06-15

    Selective doping of a Zn impurity at the group III site in a Cu(In, Ga)Se{sub 2} (CIGS) film was performed by the doping of Zn at the first stage of the three-stage method. The p-type CIGS:Zn film was obtained, which is in contrast to the n-type CIGS:Zn film obtained by the Zn impurity doping at the second and third-stages. Based on excitation intensity dependence of photoluminescence (PL) at low-temperature, the change in the acceptor level was observed. The enhancement of carrier concentration as a result of Zn-doping in the p-type CIGS:Zn film was observed. The CIGS:Zn solar cells exhibited η of 14.5% and V{sub oc} of 0.658 V, which are higher than that of the corresponding solar cells using the undoped CIGS films. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  5. Solar surface magnetism and irradiance on time scales

    NARCIS (Netherlands)

    Domingo, V.; Ermolli, I.; Fox, P.; Fröhlich, C.; Haberreiter, M.; Krivova, N.; Kopp, G.; Schmutz, W.; Solanki, S.K.; Spruit, H.C.; Unruh, Y.C.; Vögler, A.

    2009-01-01

    The uninterrupted measurement of the total solar irradiance during the last three solar cycles and an increasing amount of solar spectral irradiance measurements as well as solar imaging observations (magnetograms and photometric data) have stimulated the development of models attributing irradiance

  6. Results from Coupled Optical and Electrical Sentaurus TCAD Models of a Gallium Phosphide on Silicon Electron Carrier Selective Contact Solar Cell

    Energy Technology Data Exchange (ETDEWEB)

    Limpert, Steven; Ghosh, Kunal; Wagner, Hannes; Bowden, Stuart; Honsberg, Christiana; Goodnick, Stephen; Bremner, Stephen; Green, Martin

    2014-06-09

    We report results from coupled optical and electrical Sentaurus TCAD models of a gallium phosphide (GaP) on silicon electron carrier selective contact (CSC) solar cell. Detailed analyses of current and voltage performance are presented for devices having substrate thicknesses of 10 μm, 50 μm, 100 μm and 150 μm, and with GaP/Si interfacial quality ranging from very poor to excellent. Ultimate potential performance was investigated using optical absorption profiles consistent with light trapping schemes of random pyramids with attached and detached rear reflector, and planar with an attached rear reflector. Results indicate Auger-limited open-circuit voltages up to 787 mV and efficiencies up to 26.7% may be possible for front-contacted devices.

  7. An empirical spectral bandwidth model for superior conjunction. [spacecraft communication

    Science.gov (United States)

    Rockwell, R. S.

    1978-01-01

    The downlink signal from spacecraft in superior solar conjunction phases suffers a great reduction in signal-to-noise ratio. Responsible in large part for this effect is the line broadening of the signal spectrum. An analytic empirical expression was developed for spectral bandwidth as a function of heliocentric distance from 1 to 20 solar radii. The study is based on spectral broadening data obtained from the superior conjunctions of Helios 1 (1975), Helios 2 (1976), and Pioneer 6 (1968). The empirical fit is based in part on a function describing the electron content in the solar corona.

  8. The Zugspitze radiative closure experiment for quantifying water vapor absorption over the terrestrial and solar infrared – Part 3: Quantification of the mid- and near-infrared water vapor continuum in the 2500 to 7800 cm−1 spectral range under atmospheric conditions

    Directory of Open Access Journals (Sweden)

    A. Reichert

    2016-09-01

    Full Text Available We present a first quantification of the near-infrared (NIR water vapor continuum absorption from an atmospheric radiative closure experiment carried out at the Zugspitze (47.42° N, 10.98° E; 2964 m a.s.l.. Continuum quantification is achieved via radiative closure using radiometrically calibrated solar Fourier transform infrared (FTIR absorption spectra covering the 2500 to 7800 cm−1 spectral range. The dry atmospheric conditions at the Zugspitze site (IWV 1.4 to 3.3 mm enable continuum quantification even within water vapor absorption bands, while upper limits for continuum absorption can be provided in the centers of window regions. Throughout 75 % of the 2500 to 7800 cm−1 spectral range, the Zugspitze results agree within our estimated uncertainty with the widely used MT_CKD 2.5.2 model (Mlawer et al., 2012. In the wings of water vapor absorption bands, our measurements indicate about 2–5 times stronger continuum absorption than MT_CKD, namely in the 2800 to 3000 cm−1 and 4100 to 4200 cm−1 spectral ranges. The measurements are consistent with the laboratory measurements of Mondelain et al. (2015, which rely on cavity ring-down spectroscopy (CDRS, and the calorimetric–interferometric measurements of Bicknell et al. (2006. Compared to the recent FTIR laboratory studies of Ptashnik et al. (2012, 2013, our measurements are consistent within the estimated errors throughout most of the spectral range. However, in the wings of water vapor absorption bands our measurements indicate typically 2–3 times weaker continuum absorption under atmospheric conditions, namely in the 3200 to 3400, 4050 to 4200, and 6950 to 7050 cm−1 spectral regions.

  9. A novel method to achieve selective emitter for silicon solar cell using low cost pattern-able a-Si thin films as the semi-transparent phosphorus diffusion barrier

    International Nuclear Information System (INIS)

    Chen, Da Ming; Liang, Zong Cun; Zhuang, Lin; Lin, Yang Huan; Shen, Hui

    2012-01-01

    Highlights: ► a-Si thin films as semitransparent phosphorus diffusion barriers for solar cell. ► a-Si thin films on silicon wafers were patterned by the alkaline solution. ► Selective emitter was formed with patterned a-Si as diffusion barrier for solar cell. -- Abstract: Selective emitter for silicon solar cell was realized by employing a-Si thin films as the semi-transparent diffusion barrier. The a-Si thin films with various thicknesses (∼10–40 nm) were deposited by the electron-beam evaporation technique. Emitters with sheet resistances from 37 to 145 Ω/□ were obtained via POCl 3 diffusion process. The thickness of the a-Si diffusion barrier was optimized to be 15 nm for selective emitter in our work. Homemade mask which can dissolve in ethanol was screen-printed on a-Si film to make pattern. The a-Si film was then patterned in KOH solution to form finger-like design. Selective emitter was obtainable with one-step diffusion with patterned a-Si film on. Combinations of sheet resistances for the high-/low-level doped regions of 39.8/112.1, 36.2/88.8, 35.4/73.9 were obtained. These combinations are suitable for screen-printed solar cells. This preparation method of selective emitter based on a-Si diffusion barrier is a promising approach for low cost industrial manufacturing.

  10. Solar-Geophysical Data Number 562, June 1991. Part 1 (prompt reports). Data for May, April 1991, and late data

    International Nuclear Information System (INIS)

    Coffey, H.E.

    1991-06-01

    The contents include: Detailed index for 1990-1991; Data for May 1991--Solar-terrestrial environment, IUWDS alert periods (advance and worldwide), Solar activity indices, Solar flares, Solar radio emission, Stanford mean solar magnetic field; Data for April 1991--Solar active regions, Sudden ionospheric disturbances, Solar radio spectral observations, Cosmic ray measurements by neutron monitor, Geomagnetic indices; Late data--Solar radio emission March-April 1991, Geomagnetic indices February-March 1991, Solar active regions errata March 1991

  11. A BAND SELECTION METHOD FOR SUB-PIXEL TARGET DETECTION IN HYPERSPECTRAL IMAGES BASED ON LABORATORY AND FIELD REFLECTANCE SPECTRAL COMPARISON

    Directory of Open Access Journals (Sweden)

    S. Sharifi hashjin

    2016-06-01

    Full Text Available In recent years, developing target detection algorithms has received growing interest in hyperspectral images. In comparison to the classification field, few studies have been done on dimension reduction or band selection for target detection in hyperspectral images. This study presents a simple method to remove bad bands from the images in a supervised manner for sub-pixel target detection. The proposed method is based on comparing field and laboratory spectra of the target of interest for detecting bad bands. For evaluation, the target detection blind test dataset is used in this study. Experimental results show that the proposed method can improve efficiency of the two well-known target detection methods, ACE and CEM.

  12. STATISTICS OF FLARING LOOPS OBSERVED BY NOBEYAMA RADIOHELIOGRAPH. II. SPECTRAL EVOLUTION

    International Nuclear Information System (INIS)

    Huang Guangli; Nakajima, Hiroshi

    2009-01-01

    The spectral evolution of solar microwave bursts is studied in 10 impulsive events with loop-like structures, which are selected in the flare list of Nobeyama Radioheliograph. Most events have a brighter and harder looptop (LT) with maximum time later than at least one of its two footpoints (FPs), and have a common feature of the spectral evolution in the LT and the two FPs. There are five simple impulsive bursts with a well known pattern of soft-hard-soft or soft-hard-harder (SHH). It is first found that the other five events have multiple subpeaks in their impulsive phase, and mostly have a new feature of hard-soft-hard (HSH) in each subpeak, but, the well known tendency of SHH is still maintained in the total spectral evolution of these events. All of these features in the spectral evolution of the 10 selected events are consistent with the full Sun observations of Nobeyama Radio Polarimeters in these events. The new feature of HSH may be explained by the thermal free-free emission before, during, and after these bursts, together with multiple injections of nonthermal electrons, while the SHH pattern in the total duration may be directly caused by the trapping effect.

  13. Solar energy

    International Nuclear Information System (INIS)

    Anon.

    1992-01-01

    This chapter discusses the role solar energy may have in the energy future of the US. The topics discussed in the chapter include the solar resource, solar architecture including passive solar design and solar collectors, solar-thermal concentrating systems including parabolic troughs and dishes and central receivers, photovoltaic cells including photovoltaic systems for home use, and environmental, health and safety issues

  14. Calibration corrections of solar tower flux density measurements

    International Nuclear Information System (INIS)

    Ulmer, Steffen; Luepfert, Eckhard; Pfaender, Markus; Buck, Reiner

    2004-01-01

    The PSA flux density measuring system PROHERMES measures the concentrated solar radiation in the entrance aperture of solar tower receivers with a white rotating bar as target and a CCD-camera taking images. The calibration is done with commercial flux gauges placed in the measurement plane. To improve the calibration of the system and to reveal systematic errors, measurements are performed with two different types of commercial flux gauges (Thermogage sensors with and without quartz window) and a large custom-made calorimeter used as reference. The comparison shows that the sensors without quartz window measure about 5-8% higher and the sensors with quartz window about 100% higher. This error is explained with the differences in the spectral composition of the radiation and different angles of incidence between the manufacturer calibration and the solar measurements and corrections are proposed. Spectral changes of the sunlight during the day and year can affect the measurements by more than 10%. By selecting a correction filter adapted to the camera sensitivity, this influence can be reduced to less than 2.5%. Due to the reflective properties of the target coating, changes in angle of incidence can affect the measurements. In standard solar field conditions, this error is less than 0.5%, but for special conditions a correction of the systematic error of up to 8% is proposed

  15. Spectral characterization of a newly synthesized fluorescent semicarbazone derivative and its usage as a selective fiber optic sensor for copper(II).

    Science.gov (United States)

    Oter, Ozlem; Ertekin, Kadriye; Kirilmis, Cumhur; Koca, Murat

    2007-02-19

    In this work photoluminescent properties of highly Cu(2+) selective organic fluoroionophore, semicarbazone derivative; bis(naphtho[2,1-b]furan-2-yl)methanone semicarbazone (BNF) was investigated in different solvents (dichloromethane, tetrahydrofuran, toluene and ethanol) and in polymer matrices of polyvinylchloride (PVC) and ethyl cellulose (EC) by absorption and emission spectrometry. The BNF derivative displayed enhanced fluorescence emission quantum yield, Q(f)=6.1 x 10(-2) and molar extinction coefficient, epsilon=29,000+/-65 cm(-1)M(-1) in immobilized PVC matrix, compared to 2.6 x 10(-3) and 24,573+/-115 in ethanol solution. The offered sensor exhibited remarkable fluorescence intensity quenching upon exposure to Cu(2+) ions at pH 4.0 in the concentration range of 1.0 x 10(-9) to 3.0 x 10(-4)M [Cu(2+)] while the effects of the responding ions (Ca(2+), Hg(+), Pb(2+), Al(3+), Cr(3+), Mn(2+), Mg(2+), Sn(2+), Cd(2+), Co(2+) and Ni(2+)) were less pronounced.

  16. Solar-Geophysical Data Number 564, August 1991. Part 1 (Prompt reports). Data for July, June 1991, and late data

    International Nuclear Information System (INIS)

    Coffey, H.E.

    1991-08-01

    The contents include: Detailed index for 1990-1991; Data for July 1991--Solar-terrestrial environment, IUWDS alert periods (advance and worldwide), Solar activity indices, Solar flares, Stanford mean solar magnetic field; Solar active regions, Sudden ionospheric disturbances, Solar radio spectral observations, Cosmic ray measurements by neutron monitor, Geomagnetic indices

  17. Samba Solar; Samba Solar

    Energy Technology Data Exchange (ETDEWEB)

    Thurston, Charles W.

    2012-07-01

    Brazil, the biggest country of the South American subcontinent, has discovered the power of solar energy. Brazil recently introduced net metering of solar power plants and started to open the power supply grid to PV systems. The market has great potential as Brazil is the world's sixth biggest national economy.

  18. Preliminary Results Of the 2007 Flight of the Solar Bolometric Imager at Solar Minimum

    Science.gov (United States)

    Bernasconi, P. N.; Foukal, P. V.; Eaton, H. H.; Noble, M.

    2008-05-01

    On September 13 2007, the Solar Bolometric Imager (SBI) successfully observed the Sun for several hours while suspended from a balloon in the stratosphere above New Mexico. The SBI represents a totally new approach in finding the sources of the solar irradiance variation. The SBI detector is an array of 320x240 thermal IR elements whose spectral absorptance has been extended and flattened by a deposited layer of gold-black. The telescope is a 30-cm Dall-Kirkham with uncoated primary and secondary Pyrex mirrors. The combination of telescope and bolometric array provide an image of the Sun with a constant spectral response between ~ 280 and 2600 nm, over a field of view of 960 x 720 arcsec with a pixel size of 3 arcsec. This is the second successful flight of SBI, following a successful one on September 2003 which produced the first measurements in broad band of the center-to-limb variation of bolometric facular contrast (a flight attempt from Antarctica in 2006 was aborted). This latest flight provided bolometric (integrated light) maps of the solar photosphere during a time of minimum of solar activity. The SBI imagery will enable us to evaluate the photometric contribution of weak magnetic structures (e.g. network) more accurately than has been achievable with spectrally selective imaging over restricted wavebands. It will also enable us to investigate the presence, if any, of other thermal structures unrelated to magnetic activity, such as e.g. giant cells and pole-to-equator temperature gradients. During the 16 hour flight the SBI gathered several thousand bolometric images that are now being processed to produce full-disk maps of spatial variation in total solar output at solar minimum. The SBI flight is also providing important engineering data to validate the space worthiness of the novel gold-blackened thermal array detectors. In this paper we will briefly describe the characteristics of the SBI, its in-flight performance, and we will present the first

  19. Properties of the suprathermal heavy ion population near 1 AU during solar cycles 23 and 24

    Energy Technology Data Exchange (ETDEWEB)

    Dayeh, Maher A., E-mail: maldayeh@swri.edu; Ebert, Robert W. [Southwest Research Institute, 6220 Culebra Road, San Antonio, TX 78023 (United States); Desai, Mihir I. [Southwest Research Institute, 6220 Culebra Road, San Antonio, TX 78023 (United States); Department of Physics and Astronomy, University of Texas at San Antonio, TX 78249 (United States); Mason, Glenn M. [Johns Hopkins University Applied Physics Laboratory, Laurel, MD 20723 (United States)

    2016-03-25

    Using measurements from the Advanced Composition Explorer/Ultra-Low Energy Isotope Spectrometer (ACE/ULEIS) near 1 AU, we surveyed the composition and spectra of heavy ions (He-through-Fe) during interplanetary quiet times from 1998 January 1 to 2014 December 31 at suprathermal energies between ∼0.11 and ∼1.28 MeV nucleon{sup −1}. The selected time period covers the maxima of solar cycles 23 and 24 and the extended solar minimum in between. We find the following: (1) The number of quiet-hours in each year correlates well with the sunspot number, year 2009 was the quietest for about 90% of the time; (2) The composition of the quiet-time suprathermal heavy ion population ({sup 3}He, C-through-O, and Fe) correlates well with the level of solar activity, exhibiting SEP-like composition signatures during solar maximum, and CIR- or solar wind-like composition during solar minimum; (3) The heavy ion spectra at ∼0.11-0.32 MeV nucleon{sup −1} exhibit suprathermal tails with power-law spectral indices ranging from 1.4 to 2.7. (4) Fe spectral indices get softer (steeper) from solar minimum of cycle 23 to solar cycle 24 maximum. These results imply that during IP quiet times and at energies above ∼0.1 MeV nucleon{sup −1}, the IP medium is dominated by material from prior solar and interplanetary events.

  20. Detecting photovoltaic solar panels using hyperspectral imagery and estimating solar power production

    Science.gov (United States)

    Czirjak, Daniel

    2017-04-01

    Remote sensing platforms have consistently demonstrated the ability to detect, and in some cases identify, specific targets of interest, and photovoltaic solar panels are shown to have a unique spectral signature that is consistent across multiple manufacturers and construction methods. Solar panels are proven to be detectable in hyperspectral imagery using common statistical target detection methods such as the adaptive cosine estimator, and false alarms can be mitigated through the use of a spectral verification process that eliminates pixels that do not have the key spectral features of photovoltaic solar panel reflectance spectrum. The normalized solar panel index is described and is a key component in the false-alarm mitigation process. After spectral verification, these solar panel arrays are confirmed on openly available literal imagery and can be measured using numerous open-source algorithms and tools. The measurements allow for the assessment of overall solar power generation capacity using an equation that accounts for solar insolation, the area of solar panels, and the efficiency of the solar panels conversion of solar energy to power. Using a known location with readily available information, the methods outlined in this paper estimate the power generation capabilities within 6% of the rated power.

  1. Solar Surface Convection

    Directory of Open Access Journals (Sweden)

    Nordlund Åke

    2009-04-01

    Full Text Available We review the properties of solar convection that are directly observable at the solar surface, and discuss the relevant underlying physics, concentrating mostly on a range of depths from the temperature minimum down to about 20 Mm below the visible solar surface.The properties of convection at the main energy carrying (granular scales are tightly constrained by observations, in particular by the detailed shapes of photospheric spectral lines and the topology (time- and length-scales, flow velocities, etc. of the up- and downflows. Current supercomputer models match these constraints very closely, which lends credence to the models, and allows robust conclusions to be drawn from analysis of the model properties.At larger scales the properties of the convective velocity field at the solar surface are strongly influenced by constraints from mass conservation, with amplitudes of larger scale horizontal motions decreasing roughly in inverse proportion to the scale of the motion. To a large extent, the apparent presence of distinct (meso- and supergranulation scales is a result of the folding of this spectrum with the effective “filters” corresponding to various observational techniques. Convective motions on successively larger scales advect patterns created by convection on smaller scales; this includes patterns of magnetic field, which thus have an approximately self-similar structure at scales larger than granulation.Radiative-hydrodynamical simulations of solar surface convection can be used as 2D/3D time-dependent models of the solar atmosphere to predict the emergent spectrum. In general, the resulting detailed spectral line profiles agree spectacularly well with observations without invoking any micro- and macroturbulence parameters due to the presence of convective velocities and atmosphere inhomogeneities. One of the most noteworthy results has been a significant reduction in recent years in the derived solar C, N, and O abundances with

  2. Solar-Geophysical Data Number 545, January 1990. Part 1 (prompt reports). Data for December, November 1989, and late data

    International Nuclear Information System (INIS)

    Coffey, H.E.

    1990-01-01

    Contents include: detailed index for 1989; data for December 1989--solar-terrestrial environment, IUWDS alert periods (advance and worldwide), solar-activity indices, solar flares, solar radio emission, Stanford mean solar magnetic field; data for November 1989--solar-active regions, sudden ionospheric disturbances, solar radio spectral observations, cosmic-ray measurements by neutron monitor, geomagnetic indices; late data--geomagnetic indices September-October 1989, solar-active regions-carrington rotation 1821 October 1989

  3. Solar-Geophysical Data Number 539, July 1989. Part 1 (prompt reports). Data for June, May 1989, and late data

    International Nuclear Information System (INIS)

    Coffey, H.E.

    1989-07-01

    Contents include: detailed index for 1988-1989; data for June 1989 -- IUWDS alert periods (advance and worldwide), solar-activity indices, solar flares, solar radio emission, Stanford mean solar magnetic field; data for May 1989 -- solar active regions, sudden ionospheric disturbances, solar radio spectral observations, cosmic-ray measurements by neutron monitor, geomagnetic indices; late data -- solar radio emission (Nancay 169-MHz solar interferometric chart, May 1989)

  4. Solar-Geophysical Data Number 551, July 1990. Part 1 (prompt reports). Data for June, May 1990 and late data

    International Nuclear Information System (INIS)

    Coffey, H.E.

    1990-07-01

    ;Contents: Detailed index for 1989-1990; Data for June 1990--Solar-terrestrial environment, IUWDS alert periods (Advance and worldwide), Solar activity indices, Solar flares, Solar radio emission, Stanford mean solar magnetic field; Data for May 1990--Solar active regions, Sudden ionospheric disturbances, Solar radio spectral observations, Cosmic ray measurements by neutron monitor, Geomagnetic indices; Late data--Geomagnetic indices February-April 1990--sudden commencements/solar flare effects

  5. TiO2 Solar Photocatalytic Reactor Systems: Selection of Reactor Design for Scale-up and Commercialization—Analytical Review

    Directory of Open Access Journals (Sweden)

    Yasmine Abdel-Maksoud

    2016-09-01

    Full Text Available For the last four decades, viability of photocatalytic degradation of organic compounds in water streams has been demonstrated. Different configurations for solar TiO2 photocatalytic reactors have been used, however pilot and demonstration plants are still countable. Degradation efficiency reported as a function of treatment time does not answer the question: which of these reactor configurations is the most suitable for photocatalytic process and optimum for scale-up and commercialization? Degradation efficiency expressed as a function of the reactor throughput and ease of catalyst removal from treated effluent are used for comparing performance of different reactor configurations to select the optimum for scale-up. Comparison included parabolic trough, flat plate, double skin sheet, shallow ponds, shallow tanks, thin-film fixed-bed, thin film cascade, step, compound parabolic concentrators, fountain, slurry bubble column, pebble bed and packed bed reactors. Degradation efficiency as a function of system throughput is a powerful indicator for comparing the performance of photocatalytic reactors of different types and geometries, at different development scales. Shallow ponds, shallow tanks and fountain reactors have the potential of meeting all the process requirements and a relatively high throughput are suitable for developing into continuous industrial-scale treatment units given that an efficient immobilized or supported photocatalyst is used.

  6. Solar Features - Solar Flares

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — A solar flare is a short-lived sudden increase in the intensity of radiation emitted in the neighborhood of sunspots. For many years it was best monitored in the...

  7. Adaptive Spectral Doppler Estimation

    DEFF Research Database (Denmark)

    Gran, Fredrik; Jakobsson, Andreas; Jensen, Jørgen Arendt

    2009-01-01

    . The methods can also provide better quality of the estimated power spectral density (PSD) of the blood signal. Adaptive spectral estimation techniques are known to pro- vide good spectral resolution and contrast even when the ob- servation window is very short. The 2 adaptive techniques are tested......In this paper, 2 adaptive spectral estimation techniques are analyzed for spectral Doppler ultrasound. The purpose is to minimize the observation window needed to estimate the spectrogram to provide a better temporal resolution and gain more flexibility when designing the data acquisition sequence...... and compared with the averaged periodogram (Welch’s method). The blood power spectral capon (BPC) method is based on a standard minimum variance technique adapted to account for both averaging over slow-time and depth. The blood amplitude and phase estimation technique (BAPES) is based on finding a set...

  8. Upconverter solar cells: materials and applications

    NARCIS (Netherlands)

    de Wild, J.; Meijerink, A.; Rath, J.K.; van Sark, W.G.J.H.M.; Schropp, R.E.I.

    2011-01-01

    Spectral conversion of sunlight is a promising route to reduce spectral mismatch losses that are responsible for the major part of the efficiency losses in solar cells. Both upconversion and downconversion materials are presently explored. In an upconversion process, photons with an energy lower

  9. Solar Cookers.

    Science.gov (United States)

    King, Richard C.

    1981-01-01

    Describes the use of solar cookers in the science classroom. Includes instructions for construction of a solar cooker, an explanation of how solar cookers work, and a number of suggested activities. (DS)

  10. SPECTRAL SMILE CORRECTION IN CRISM HYPERSPECTRAL IMAGES

    Science.gov (United States)

    Ceamanos, X.; Doute, S.

    2009-12-01

    The Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) is affected by a common artifact in "push-broom" sensors, the so-called "spectral smile". As a consequence, both central wavelength and spectral width of the spectral response vary along the across-track dimension, thus giving rise to a shifting and smoothing of spectra (see Fig. 1 (left)). In fact, both effects are greater for spectra on the edges, while they are minimum for data acquired by central detectors, the so-called "sweet spot". The prior artifacts become particularly critical for Martian observations which contain steep spectra such as CO2 ice-rich polar images. Fig. 1 (right) shows the horizontal brightness gradient which appears in every band corresponding to a steep portion of spectra. The correction of CRISM spectral smile is addressed using a two-step method which aims at modifying data sensibly in order to mimic the optimal CRISM response. First, all spectra, which are previously interpolated by cubic splines, are resampled to the "sweet spot" wavelengths in order to overcome the spectra shift. Secondly, the non-uniform spectral width is overcome by mimicking an increase of spectral resolution thanks to a spectral sharpening. In order to minimize noise, only bands particularly suffering from smile are selected. First, bands corresponding to the outliers of the Minimum Noise Transformation (MNF) eigenvector, which corresponds to the MNF band related to smile (MNF-smile), are selected. Then, a spectral neighborhood Θi, which takes into account the local spectral convexity or concavity, is defined for every selected band in order to maximize spectral shape preservation. The proposed sharpening technique takes into account both the instrument parameters and the observed spectra. First, every reflectance value belonging to a Θi is reevaluated by a sharpening which depends on a ratio of the spectral width of the current detector and the "sweet spot" one. Then, the optimal degree of

  11. SOLAR-ISS: A new reference spectrum based on SOLAR/SOLSPEC observations

    Science.gov (United States)

    Meftah, M.; Damé, L.; Bolsée, D.; Hauchecorne, A.; Pereira, N.; Sluse, D.; Cessateur, G.; Irbah, A.; Bureau, J.; Weber, M.; Bramstedt, K.; Hilbig, T.; Thiéblemont, R.; Marchand, M.; Lefèvre, F.; Sarkissian, A.; Bekki, S.

    2018-03-01

    Context. Since April 5, 2008 and up to February 15, 2017, the SOLar SPECtrometer (SOLSPEC) instrument of the SOLAR payload on board the International Space Station (ISS) has performed accurate measurements of solar spectral irradiance (SSI) from the middle ultraviolet to the infrared (165 to 3088 nm). These measurements are of primary importance for a better understanding of solar physics and the impact of solar variability on climate. In particular, a new reference solar spectrum (SOLAR-ISS) is established in April 2008 during the solar minima of cycles 23-24 thanks to revised engineering corrections, improved calibrations, and advanced procedures to account for thermal and aging corrections of the SOLAR/SOLSPEC instrument. Aims: The main objective of this article is to present a new high-resolution solar spectrum with a mean absolute uncertainty of 1.26% at 1σ from 165 to 3000 nm. This solar spectrum is based on solar observations of the SOLAR/SOLSPEC space-based instrument. Methods: The SOLAR/SOLSPEC instrument consists of three separate double monochromators that use concave holographic gratings to cover the middle ultraviolet (UV), visible (VIS), and infrared (IR) domains. Our best ultraviolet, visible, and infrared spectra are merged into a single absolute solar spectrum covering the 165-3000 nm domain. The resulting solar spectrum has a spectral resolution varying between 0.6 and 9.5 nm in the 165-3000 nm wavelength range. We build a new solar reference spectrum (SOLAR-ISS) by constraining existing high-resolution spectra to SOLAR/SOLSPEC observed spectrum. For that purpose, we account for the difference of resolution between the two spectra using the SOLAR/SOLSPEC instrumental slit functions. Results: Using SOLAR/SOLSPEC data, a new solar spectrum covering the 165-3000 nm wavelength range is built and is representative of the 2008 solar minimum. It has a resolution better than 0.1 nm below 1000 nm and 1 nm in the 1000-3000 nm wavelength range. The new

  12. Within- and between- class variability of spectrally similar tree species

    CSIR Research Space (South Africa)

    Debba, Pravesh

    2009-07-01

    Full Text Available ) using sequential selection of bands, for example, every 5th, 9th, 15th, 19th or 25th band selected and (vii) spectral degradation of the spectral bands by averaging the reflectance values for every 5th, 9th, 15th, 19th or 25th band. The authors concluded...

  13. Cryogenic Selective Surfaces

    Data.gov (United States)

    National Aeronautics and Space Administration — Selective surfaces have wavelength dependent emissivity/absorption. These surfaces can be designed to reflect solar radiation, while maximizing infrared emittance,...

  14. The solar element

    DEFF Research Database (Denmark)

    Kragh, Helge

    2009-01-01

    of the nineteenth century. In the modest form of a yellow spectral line known as D3, 'helium' was sometimes supposed to exist in the Sun's atmosphere, an idea which is traditionally ascribed to J. Norman Lockyer. Did Lockyer discover helium as a solar element? How was the suggestion received by chemists, physicists...... and astronomers in the period until the spring of 1895, when William Ramsay serendipitously found the gas in uranium minerals? The hypothetical element helium was fairly well known, yet Ramsay's discovery owed little or nothing to Lockyer's solar element. Indeed, for a brief while it was thought that the two...... elements might be different. The complex story of how helium became established as both a solar and terrestrial element involves precise observations as well as airy speculations. It is a story that is unique among the discovery histories of the chemical elements....

  15. Spectral Analysis of Burgundy Pinot Noir Grape Harvest Dates

    Science.gov (United States)

    Rahim, K.; Thomson, D. J.

    2009-05-01

    We perform an analysis of Burgundy pinot noir grape harvest dates. This annual record reports the annual grape harvest date in days after September 1st, which has been used in summer temperature reconstructions. We perform spectral analysis and dynamic spectral analysis of the data where we find evidence of coherence indicating solar influence. Specifically we find structure in the dynamic spectra indicating solar influence, and there is evidence of the non-stationary structure associated with Seuss cycles as seen in other historical temperature data.

  16. SPHEREx: Science Opportunities for Solar System Astronomy

    Science.gov (United States)

    Lisse, Carey Michael; SPHEREx Science Team

    2018-01-01

    SPHEREx, a mission in NASA's Medium Explorer (MIDEX) program that was selected for Phase A study in August 2017, will perform an all-sky near-infrared spectral survey between 0.75 - 5.0 µm in R = 41 filters, and with R = 135 coverage from 4.2 - 5.0 µm, reaching L ~ 19 (5-sigma).SPHEREx has high potential for solar system science. The 96-band survey will cover the entire sky 4 times over the course of 2 years, including thousands of foreground solar system asteroids, comets, Trojans, and KBOs. By canvassing the entire solar system for 2 years, SPHEREx has the potential not only to achieve a relatively complete sensitivity limited survey of the solar system's bodies, but also some capability to search for variation in these bodies over time.For example, the large legacy dataset of SPHEREx will update the WISE catalogue of asteroid sizes and albedos by providing a spectral survey of tens of thousands of bodies. It will provide spectral classification of hundreds of Trojan asteroids, allowing for direct comparison to the asteroid results. It will extend optical surveys of comet composition by dynamical type to hundreds of objects in the NIR, while determining water/dust/CO/CO2 activity vs distance. SPHEREx will also map in great temporal and spatial detail the zodiacal dust debris disk cloud that these bodies produce, providing an unprecedented level of information concerning the sources and sinks of this material.In this paper, we discuss the data release schedule and some example science studies the planetary astronomy community will be able to access using the SPHEREx database. We also outline existing plans within the SPHEREx team to develop software tools to enable easy access to the data and to conduct catalog searches, and ways in which the community can provide input to the SPHEREx Science Team on scientific studies and data/software requirements for those studies, enabling a large number of scientific studies while finding interesting targets for follow

  17. 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.

  18. Testing a solar-blind pyrometer

    Science.gov (United States)

    Ballestrín, J.; Marzo, A.; Cañadas, I.; Rodríguez, J.

    2010-12-01

    Surface temperatures are key parameters in many concentrated solar radiation applications. Pyrometric temperature measurement of solar irradiated material surfaces is the alternative to contact measurement techniques, which are inadequate for measuring the temperatures of such surfaces. However, reflected solar radiation is an important uncertainty variable in this non-contact methodology. A promising method for eliminating this solar perturbation is by using centred passband filters on the atmospheric solar absorption bands, creating solar-blind pyrometric systems. A commercial pyrometer has been tested in the wavelength band at around 1.4 µm in the solar furnace at Plataforma Solar de Almería, showing its advantages and limitations. An estimation of temperature measurement uncertainty for a real case is presented with theory and experiment in agreement: the higher the temperature, the lower the uncertainty. Another experiment has shown that the pyrometer measures temperature properly even through quartz windows in this spectral range.

  19. Viscosity, surface tension, density and contact angle of selected PbI2, PbCl2 and methylammonium lead halide perovskite solutions used in perovskite solar cells

    Science.gov (United States)

    Ahmadian-Yazdi, Mohammad-Reza; Rahimzadeh, Amin; Chouqi, Zineb; Miao, Yihe; Eslamian, Morteza

    2018-02-01

    Perovskite solar cells (PSCs) are currently under vigorous research and development, owing to their compelling power conversion efficiencies. PSCs are solution-processed and, therefore, are fabricated using casting and printing methods, such as spin, spray and blade coating. The coating characteristics significantly depend on the physical and rheological properties of the solutions. Thus, due to the scarcity of such properties, in this work, we report the surface tension, viscosity, density, and contact angle of selected methylammonium lead halide perovskite solutions, in order to gain insight into the behavior of the perovskite solutions and the range of such physical properties. The contact angles were measured on PEDOT:PSS and compact TiO2 (c-TiO2) substrates, commonly used as the underneath layers of the perovskite film. In total, 12 solutions of CH3NH3PbI3 and CH3NH3PbI3-xClx dissolved in common solvents, as well as solutions of PbI2, PbCl2, and CH3NH3I were tested. Among the results, it is shown that the tested perovskite solutions are Newtonian, the apparent contact angles on the mesoporous TiO2 (m-TiO2) are close to zero, on the PEDOT:PSS are around 10°, and on the c-TiO2 are around 30°. Also, contact angle hysteresis is observed in the case of the c-TiO2 substrates. Representative impact dynamics and spreading of perovskite solution droplets are also studied, to demonstrate the importance of the solution properties and process parameters on the coating process.

  20. Solar Energy.

    Science.gov (United States)

    Eaton, William W.

    Presented is the utilization of solar radiation as an energy resource principally for the production of electricity. Included are discussions of solar thermal conversion, photovoltic conversion, wind energy, and energy from ocean temperature differences. Future solar energy plans, the role of solar energy in plant and fossil fuel production, and…