Gregg, Watson W.; Rousseaux, Cecile S.
2016-01-01
The importance of including directional and spectral light in simulations of ocean radiative transfer was investigated using a coupled biogeochemical-circulation-radiative model of the global oceans. The effort focused on phytoplankton abundances, nutrient concentrations and vertically-integrated net primary production. The importance was approached by sequentially removing directional (i.e., direct vs. diffuse) and spectral irradiance and comparing results of the above variables to a fully directionally and spectrally-resolved model. In each case the total irradiance was kept constant; it was only the pathways and spectral nature that were changed. Assuming all irradiance was diffuse had negligible effect on global ocean primary production. Global nitrate and total chlorophyll concentrations declined by about 20% each. The largest changes occurred in the tropics and sub-tropics rather than the high latitudes, where most of the irradiance is already diffuse. Disregarding spectral irradiance had effects that depended upon the choice of attenuation wavelength. The wavelength closest to the spectrally-resolved model, 500 nm, produced lower nitrate (19%) and chlorophyll (8%) and higher primary production (2%) than the spectral model. Phytoplankton relative abundances were very sensitive to the choice of non-spectral wavelength transmittance. The combined effects of neglecting both directional and spectral irradiance exacerbated the differences, despite using attenuation at 500 nm. Global nitrate decreased 33% and chlorophyll decreased 24%. Changes in phytoplankton community structure were considerable, representing a change from chlorophytes to cyanobacteria and coccolithophores. This suggested a shift in community function, from light-limitation to nutrient limitation: lower demands for nutrients from cyanobacteria and coccolithophores favored them over the more nutrient-demanding chlorophytes. Although diatoms have the highest nutrient demands in the model, their
International Nuclear Information System (INIS)
Torres-Ramírez, M.; Elizondo, D.; García-Domingo, B.; Nofuentes, G.; Talavera, D.L.
2015-01-01
This work is aimed at verifying that in sunny inland locations artificial intelligence techniques may provide an estimation of the spectral irradiance with adequate accuracy for photovoltaic applications. An ANN (artificial neural network) based method was developed, trained and tested to model the spectral distributions between wavelengths ranging from 350 to 1050 nm. Only commonly available input data such as geographical information regarding location, specific date and time together with horizontal global irradiance and ambient temperature are required. Historical information from a 24-month experimental campaign carried out in Jaén (Spain) provided the necessary data to train and test the ANN tool. A Kohonen self-organized map was used as innovative technique to classify the whole input dataset and build a small and representative training dataset. The shape of the spectral irradiance distribution, the in-plane global irradiance (G T ) and irradiation (H T ) and the APE (average photon energy) values obtained through the ANN method were statistically compared to the experimental ones. In terms of shape distribution fitting, the mean relative deformation error stays below 4.81%. The root mean square percentage error is around 6.89% and 0.45% when estimating G T and APE, respectively. Regarding H T , errors lie below 3.18% in all cases. - Highlights: • ANN-based model to estimate the spectral irradiance distribution in sunny inland locations. • MRDE value stay below 4.81% in spectral irradiance distribution shape fitting. • RMSPE is about 6.89% for the in-plane global irradiance and 0.45% for the average photon energy. • Errors stay below 3.18% for all the months of the year in incident irradiation terms. • Improvement of assessment of the impact of the solar spectrum in the performance of a PV module
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.
Improving Soft X-Ray Spectral Irradiance Models for Use Throughout the Solar System
Eparvier, F. G.; Thiemann, E.; Woods, T. N.
2017-12-01
Understanding the effects of solar variability on planetary atmospheres has been hindered by the lack of accurate models and measurements of the soft x-ray (SXR) spectral irradiance (0-6 nm). Most measurements of the SXR have been broadband and are difficult to interpret due to changing spectral distribution under the pass band of the instruments. Models that use reference spectra for quiet sun, active region, and flaring contributions to irradiance have been made, but with limited success. The recent Miniature X-ray Solar Spectrometer (MinXSS) CubeSat made spectral measurements in the 0.04 - 3 nm range from June 2016 to May 2017, observing the Sun at many different levels of activity. In addition, the Solar Dynamics Observatory (SDO) EUV Variability Experiment (EVE) has observed the Sun since May 2010, in both broad bands (including a band at 0-7 nm) and spectrally resolved (6-105 nm at 0.1 nm resolution). We will present an improved model of the SXR based on new reference spectra from MinXSS and SDO-EVE. The non-flaring portion of the model is driven by broadband SXR measurements for determining activity level and relative contributions of quiet and active sun. Flares are modeled using flare temperatures from the GOES X-Ray Sensors. The improved SXR model can be driven by any sensors that provide a measure of activity level and flare temperature from any vantage point in the solar system. As an example, a version of the model is using the broadband solar irradiance measurements from the MAVEN EUV Monitor at Mars will be presented.
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.
The delta-Sobolev approach for modeling solar spectral irradiance and radiance
International Nuclear Information System (INIS)
Xiang, Xuwu.
1990-01-01
The development and evaluation of a solar radiation model is reported, which gives irradiance and radiance results at the bottom and top of an atmosphere of specified optical depth for each of 145 spectral intervals from 0.29 to 4.05 microns. Absorption by water vapor, aerosols, ozone, and uniformly mixed gases; scattering by molecules and aerosols; and non-Lambertian surface reflectance are included in the model. For solving the radiative transfer equation, an innovative delta-Sobolev method is developed. It applies a delta-function modification to the conventional Sobolev solutions in a way analogous to the delta-Eddington method. The irradiance solution by the delta-Sobolev method turns out to be mathematically identical to the delta-Eddington approximation. The radiance solution by the delta-Sobolov method provides a convenient way to obtain the directional distribution pattern of the radiation transfer field, a feature unable to be obtained by most commonly used approximation methods. Such radiance solutions are also especially useful in models for satellite remote sensing. The model is tested against the rigorous Dave model, which solves the radiation transfer problem by the spherical harmonic method, an accurate but very time consuming process. Good agreement between the current model results and those of Dave's model are observed. The advantages of the delta-Sobolev model are simplicity, reasonable accuracy and capability for implementation on a minicomputer or microcomputer
Chamberlin, Phillip
2008-01-01
The Flare Irradiance Spectral Model (FISM) is an empirical model of the solar irradiance spectrum from 0.1 to 190 nm at 1 nm spectral resolution and on a 1-minute time cadence. The goal of FISM is to provide accurate solar spectral irradiances over the vacuum ultraviolet (VUV: 0-200 nm) range as input for ionospheric and thermospheric models. The seminar will begin with a brief overview of the FISM model, and also how the Solar Dynamics Observatory (SDO) EUV Variability Experiment (EVE) will contribute to improving FISM. Some current studies will then be presented that use FISM estimations of the solar VUV irradiance to quantify the contributions of the increased irradiance from flares to Earth's increased thermospheric and ionospheric densites. Initial results will also be presented from a study looking at the electron density increases in the Martian atmosphere during a solar flare. Results will also be shown quantifying the VUV contributions to the total flare energy budget for both the impulsive and gradual phases of solar flares. Lastly, an example of how FISM can be used to simplify the design of future solar VUV irradiance instruments will be discussed, using the future NOAA GOES-R Extreme Ultraviolet and X-Ray Sensors (EXIS) space weather instrument.
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
Directory of Open Access Journals (Sweden)
I. Foyo-Moreno
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
Extreme ultraviolet spectral irradiance measurements since 1946
Schmidtke, G.
2015-03-01
In the physics of the upper atmosphere the solar extreme ultraviolet (EUV) radiation plays a dominant role controlling most of the thermospheric/ionospheric (T/I) processes. Since this part of the solar spectrum is absorbed in the thermosphere, platforms to measure the EUV fluxes became only available with the development of rockets reaching altitude levels exceeding 80 km. With the availability of V2 rockets used in space research, recording of EUV spectra started in 1946 using photographic films. The development of pointing devices to accurately orient the spectrographs toward the sun initiated intense activities in solar-terrestrial research. The application of photoelectric recording technology enabled the scientists placing EUV spectrometers aboard satellites observing qualitatively strong variability of the solar EUV irradiance on short-, medium-, and long-term scales. However, as more measurements were performed more radiometric EUV data diverged due to the inherent degradation of the EUV instruments with time. Also, continuous recording of the EUV energy input to the T/I system was not achieved. It is only at the end of the last century that there was progress made in solving the serious problem of degradation enabling to monitore solar EUV fluxes with sufficient radiometric accuracy. The data sets available allow composing the data available to the first set of EUV data covering a period of 11 years for the first time. Based on the sophisticated instrumentation verified in space, future EUV measurements of the solar spectral irradiance (SSI) are promising accuracy levels of about 5% and less. With added low-cost equipment, real-time measurements will allow providing data needed in ionospheric modeling, e.g., for correcting propagation delays of navigation signals from space to earth. Adding EUV airglow and auroral emission monitoring by airglow cameras, the impact of space weather on the terrestrial T/I system can be studied with a spectral terrestrial
The spectral irradiance traceability chain at PTB
International Nuclear Information System (INIS)
Sperfeld, P.; Pape, S.; Nevas, S.
2013-01-01
Spectral irradiance is a fundamental radiometric unit. Its application to measurement results requires qualified traceability to basic units of the international system of units (Système international d’unités, SI). The Physikalisch-Technische Bundesanstalt (PTB) is amongst other national metrological institutes (NMIs) responsible for the realization, maintenance and dissemination of various radiometric and photometric units based on and traceable to national standards. The unit of spectral irradiance is realized and represented by a blackbody-radiator as the national primary standard of the PTB. Based on Planck’s radiation law, the irradiance is calculated and realized for any wavelength taking into account the exact knowledge of the radiation temperature and the geometrical parameters. Using a double-monochromator-based spectroradiometer system, secondary standard lamps can be calibrated by direct comparison to the blackbody-radiator (substitution method). These secondary standard lamps are then used at the PTB to calibrate standard lamps of customers. The customers themselves use these so-called transfer standards to calibrate their working standard lamps. These working standards are then used to calibrate own spectroradiometers or sources. This rather complex calibration chain is a common procedural method that for the customers generally leads to satisfying measurement results on site. Nevertheless, the standard lamps in use have to fulfill highest requirements concerning stability and reproducibility. Only this allows achieving comparably low transfer measurement uncertainties, which occur at each calibration step. Thus, the PTB is constantly investigating the improvement and further development of transfer standards and measurement methods for various spectral regions. The realization and dissemination of the spectral irradiance using the blackbody-radiator at the PTB is accomplished with worldwide approved minimized measurement uncertainties confirmed
The spectral irradiance traceability chain at PTB
Energy Technology Data Exchange (ETDEWEB)
Sperfeld, P.; Pape, S.; Nevas, S. [Physikalisch-Technische Bundesanstalt, Bundesallee 10, 381160 Braunschweig (Germany)
2013-05-10
Spectral irradiance is a fundamental radiometric unit. Its application to measurement results requires qualified traceability to basic units of the international system of units (Systeme international d'unites, SI). The Physikalisch-Technische Bundesanstalt (PTB) is amongst other national metrological institutes (NMIs) responsible for the realization, maintenance and dissemination of various radiometric and photometric units based on and traceable to national standards. The unit of spectral irradiance is realized and represented by a blackbody-radiator as the national primary standard of the PTB. Based on Planck's radiation law, the irradiance is calculated and realized for any wavelength taking into account the exact knowledge of the radiation temperature and the geometrical parameters. Using a double-monochromator-based spectroradiometer system, secondary standard lamps can be calibrated by direct comparison to the blackbody-radiator (substitution method). These secondary standard lamps are then used at the PTB to calibrate standard lamps of customers. The customers themselves use these so-called transfer standards to calibrate their working standard lamps. These working standards are then used to calibrate own spectroradiometers or sources. This rather complex calibration chain is a common procedural method that for the customers generally leads to satisfying measurement results on site. Nevertheless, the standard lamps in use have to fulfill highest requirements concerning stability and reproducibility. Only this allows achieving comparably low transfer measurement uncertainties, which occur at each calibration step. Thus, the PTB is constantly investigating the improvement and further development of transfer standards and measurement methods for various spectral regions. The realization and dissemination of the spectral irradiance using the blackbody-radiator at the PTB is accomplished with worldwide approved minimized measurement uncertainties
Spectral Irradiance Measurements Based on Detector
International Nuclear Information System (INIS)
Lima, M S; Menegotto, T; Duarte, I; Da Silva, T Ferreira; Alves, L C; Alvarenga, A D; Almeida, G B; Couceiro, I B; Teixeira, R N
2015-01-01
This paper presents the preliminary results of the realization of absolute spectral irradiance scale at INMETRO in the ultraviolet, visible and infrared regions using filter radiometers as secondary standards. In the construction of these instruments are used, at least, apertures, interference filters and a trap detector. In the assembly of the trap detectors it was necessary to characterize several photocells in spatial uniformity and shunt resistance. All components were calibrated and these results were analyzed to mount the filter radiometer
Solar Spectral Irradiance Changes During Cycle 24
Marchenko, Sergey; Deland, Matthew
2014-01-01
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 approximately 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 lambda approximately or greater than 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.
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 (F_{10.7} in the tropics. The peak zonal mean tropical temperature response using the SORCE SSI is nearly 2 K per 100 units F_{10.7} – 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
Evaluation of the desert dust effects on global, direct and diffuse spectral ultraviolet irradiance
Directory of Open Access Journals (Sweden)
R. Román
2013-01-01
Full Text Available This paper presents a study of a strong desert dust episode over the Iberian Peninsula, and its effect on the spectral ultraviolet (UV irradiance in Granada, Spain. Remote sensing measurements, forecast models, and synoptic analysis are used to identify a Saharan desert dust outbreak that affected the Iberian Peninsula starting 20 July 2009. Additionally, a Bentham DMc150 spectroradiometer is employed to obtain global, direct and diffuse spectral UV irradiances every 15 minutes in Granada. The desert dust caused a large attenuation of the direct UV irradiance (up to 55%, while the diffuse UV irradiance increased up to 40% at 400 nm. The UVSPEC/LibRadtran radiative transfer model is used to study the spectral dependence of the experimental UV irradiance ratios (ratios of spectral irradiance for the day with the highest aerosol load to that measured in days with low–moderate load. The spectral increase or decrease of the UV direct irradiance ratios depends on a new parameter: a threshold wavelength. The spectral dependence of the UV diffuse irradiance ratio can be explained because under the influence of the intense dust outbreak, the Mie scattering by aerosols at shorter wavelengths is stronger than the Rayleigh scattering by gases. Finally, the sensitivity analysis of the aerosol absorption properties shows a substantial attenuation of UV spectral irradiance with a weak spectral dependence.
Parametric Explosion Spectral Model
Energy Technology Data Exchange (ETDEWEB)
Ford, S R; Walter, W R
2012-01-19
Small underground nuclear explosions need to be confidently detected, identified, and characterized in regions of the world where they have never before occurred. We develop a parametric model of the nuclear explosion seismic source spectrum derived from regional phases that is compatible with earthquake-based geometrical spreading and attenuation. Earthquake spectra are fit with a generalized version of the Brune spectrum, which is a three-parameter model that describes the long-period level, corner-frequency, and spectral slope at high-frequencies. Explosion spectra can be fit with similar spectral models whose parameters are then correlated with near-source geology and containment conditions. We observe a correlation of high gas-porosity (low-strength) with increased spectral slope. The relationship between the parametric equations and the geologic and containment conditions will assist in our physical understanding of the nuclear explosion source.
NOAA Climate Data Record (CDR) of Solar Spectral Irradiance (SSI), NRLSSI Version 2
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...
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
International Nuclear Information System (INIS)
Anav, A.; Rafanelli, C.; Di Menno, I.; Di Menno, M.
2004-01-01
The paper shows a semi-analytical method for environmental and dosimetric applications to evaluate, in clear sky conditions, the solar irradiance and the effective dose rates for some action spectra using only four spectral irradiance values at selected wavelengths in the UV-B and UV-A regions (305, 320, 340 and 380 nm). The method, named WL4UV, is based on the reconstruction of an approximated spectral irradiance that can be integrated, to obtain the solar irradiance, or convoluted with an action spectrum to obtain an effective dose rate. The parameters required in the algorithm are deduced from archived solar spectral irradiance data. This database contains measurements carried out by some Brewer spectrophotometers located in various geographical positions, at similar altitudes, with very different environmental characteristics: Rome (Italy), Ny Aalesund (Svalbard Islands (Norway)) and Ushuaia (Tierra del Fuego (Argentina)). To evaluate the precision of the method, a double test was performed with data not used in developing the model. Archived Brewer measurement data, in clear sky conditions, from Rome and from the National Science Foundation UV data set in San Diego (CA, USA) and Ushuaia, where SUV 100 spectro-radiometers operate, were drawn randomly. The comparison of measured and computed irradiance has a relative deviation of about ±2%. The effective dose rates for action spectra of Erythema, DNA and non-Melanoma skin cancer have a relative deviation of less than ∼20% for solar zenith angles <50 deg.. (authors)
Design principles and field performance of a solar spectral irradiance meter
Energy Technology Data Exchange (ETDEWEB)
Tatsiankou, V.; Hinzer, K.; Haysom, J.; Schriemer, H.; Emery, K.; Beal, R.
2016-08-01
A solar spectral irradiance meter (SSIM), designed for measuring the direct normal irradiance (DNI) in six wavelength bands, has been combined with models to determine key atmospheric transmittances and the resulting spectral irradiance distribution of DNI under all sky conditions. The design principles of the SSIM, implementation of a parameterized transmittance model, and field performance comparisons of modeled solar spectra with reference radiometer measurements are presented. Two SSIMs were tested and calibrated at the National Renewable Energy Laboratory (NREL) against four spectroradiometers and an absolute cavity radiometer. The SSIMs' DNI was on average within 1% of the DNI values reported by one of NREL's primary absolute cavity radiometers. An additional SSIM was installed at the SUNLAB Outdoor Test Facility in September 2014, with ongoing collection of environmental and spectral data. The SSIM's performance in Ottawa was compared against a commercial pyrheliometer and a spectroradiometer over an eight month study. The difference in integrated daily spectral irradiance between the SSIM and the ASD spectroradiometer was found to be less than 1%. The cumulative energy density collected by the SSIM over this duration agreed with that measured by an Eppley model NIP pyrheliometer to within 0.5%. No degradation was observed.
International Nuclear Information System (INIS)
Skerovic, V; Zarubica, V; Aleksic, M; Zekovic, L; Belca, I
2010-01-01
Realization of the scale of spectral responsivity of the detectors in the Directorate of Measures and Precious Metals (DMDM) is based on silicon detectors traceable to LNE-INM. In order to realize the unit of spectral irradiance in the laboratory for photometry and radiometry of the Bureau of Measures and Precious Metals, the new method based on the calibration of the spectroradiometer by comparison with standard detector has been established. The development of the method included realization of the System of Spectral Comparisons (SSC), together with the detector spectral responsivity calibrations by means of a primary spectrophotometric system. The linearity testing and stray light analysis were preformed to characterize the spectroradiometer. Measurement of aperture diameter and calibration of transimpedance amplifier were part of the overall experiment. In this paper, the developed method is presented and measurement results with the associated measurement uncertainty budget are shown.
Energy Technology Data Exchange (ETDEWEB)
Skerovic, V; Zarubica, V; Aleksic, M [Directorate of measures and precious metals, Optical radiation Metrology department, Mike Alasa 14, 11000 Belgrade (Serbia); Zekovic, L; Belca, I, E-mail: vladanskerovic@dmdm.r [Faculty of Physics, Department for Applied physics and metrology, Studentski trg 12-16, 11000 Belgrade (Serbia)
2010-10-15
Realization of the scale of spectral responsivity of the detectors in the Directorate of Measures and Precious Metals (DMDM) is based on silicon detectors traceable to LNE-INM. In order to realize the unit of spectral irradiance in the laboratory for photometry and radiometry of the Bureau of Measures and Precious Metals, the new method based on the calibration of the spectroradiometer by comparison with standard detector has been established. The development of the method included realization of the System of Spectral Comparisons (SSC), together with the detector spectral responsivity calibrations by means of a primary spectrophotometric system. The linearity testing and stray light analysis were preformed to characterize the spectroradiometer. Measurement of aperture diameter and calibration of transimpedance amplifier were part of the overall experiment. In this paper, the developed method is presented and measurement results with the associated measurement uncertainty budget are shown.
Recent Characterization of the Night-Sky Irradiance in the Visible/Near-Infrared Spectral Band
Moore, Carolynn; Wood, Michael; Bender, Edward; Hart, Steve
2018-01-01
The U.S. Army RDECOM CERDEC NVESD has made numerous characterizations of the night sky over the past 45 years. Up until the last four years, the measurement devices were highly detector-limited, which led to low spectral resolution, marginal sensitivity in no-moon conditions, and the need for inferential analysis of the resulting data. In 2014, however, the PhotoResearch Model PR-745 spectro-radiometer established a new state of the art for measurement of the integrated night-sky irradiance over the Visible-to-Near-Infrared (VNIR) spectral band (400-1050nm). This has enabled characterization of no-moon night-sky irradiance with a spectral bandwidth less than 15 nanometers, even when this irradiance is attenuated by heavy clouds or forest canopy. Since 2014, we have conducted a series of night-sky data collections at remote sites across the United States. The resulting data has provided new insights into natural radiance variations, cultural lighting impacts, and the spectrally-varying attenuation caused by cloud cover and forest canopy. Several new metrics have also been developed to provide insight into these newly-found components and temporal variations. The observations, findings and conclusions of the above efforts will be presented, including planned near-term efforts to further characterize the night-sky irradiance in the Visible/Near-Infrared spectral band.
Total and Spectral Solar Irradiance Sensor (TSIS) Project Status
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).
Remote sensing of oceanic primary production: Computations using a spectral model
Digital Repository Service at National Institute of Oceanography (India)
Sathyendranath, S.; Platt, T.; Caverhill, C.M.; Warnock, R.E.; Lewis, M.R.
A spectral model of underwater irradiance is coupled with a spectral version of the photosynthesis-light relationship to compute oceanic primary production. The results are shown to be significantly different from those obtained using...
SORCE XPS Level 3 Solar Spectral Irradiance 6-Hour Means V010
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...
Continuing the Total and Spectral Solar Irradiance Climate Data Record
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
Cai, Yaomin; Guo, Zhixiong
2018-04-20
The Monte Carlo model was developed to simulate the collimated solar irradiation transfer and energy harvest in a hollow louver made of silica glass and filled with water. The full solar spectrum from the air mass 1.5 database was adopted and divided into various discrete bands for spectral calculations. The band-averaged spectral properties for the silica glass and water were obtained. Ray tracing was employed to find the solar energy harvested by the louver. Computational efficiency and accuracy were examined through intensive comparisons of different band partition approaches, various photon numbers, and element divisions. The influence of irradiation direction on the solar energy harvest efficiency was scrutinized. It was found that within a 15° polar angle of incidence, the harvested solar energy in the louver was high, and the total absorption efficiency reached 61.2% under normal incidence for the current louver geometry.
Spectral irradiance curve calculations for any type of solar eclipse
International Nuclear Information System (INIS)
Deepak, A.; Merrill, J.E.
1974-01-01
A simple procedure is described for calculating the eclipse function (EF), alpha, and hence the spectral irradiance curve (SIC), (1-alpha), for any type of solar eclipse: namely, the occultation (partial/total) eclipse and the transit (partial/annular) eclipse. The SIC (or the EF) gives the variation of the amount (or the loss) of solar radiation of a given wavelength reaching a distant observer for various positions of the moon across the sun. The scheme is based on the theory of light curves of eclipsing binaries, the results of which are tabulated in Merrill's Tables, and is valid for all wavelengths for which the solar limb-darkening obeys the cosine law: J = /sub c/(1 - X + X cost gamma). As an example of computing the SIC for an occultation eclipse which may be total, the calculations for the March 7, 1970, eclipse are described in detail. (U.S.)
Study the Characterization of Spectral Absorbance on Irradiated Milk Protein
Fohely, F.; Suardi, N.
2018-04-01
The milk has been adopted as a structural nature food for a long era since it is containing most of the growth factors, protective agents, and enzymes needed for the body. a few attempts have been conducted to treat the dairy products especially raw milk by the means of ionizing radiation. as its production has been an expanding industry for many years due to the high demands from the consumers worldwide, there is still some doubt about preserving these products by irradiation. In this work, a preliminary effort to describe the influences of ionizing radiation on raw milk’s protein will be devoted to measuring the spectral absorbance of the total protein (after subjected to varied radiation doses) by UV-VIS-NIR spectroscopy analysis. The absorbance spectrum then analyzed based on absorbance spectra of organic compounds. A comparison is made between the effects of different radiation doses to estimate the influence in milk’s structure.
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.
Poston, Michael J.; Mahjoub, Ahmed; Ehlmann, Bethany L.; Blacksberg, Jordana; Brown, Michael E.; Carlson, Robert W.; Eiler, John M.; Hand, Kevin P.; Hodyss, Robert; Wong, Ian
2018-04-01
Understanding the history of Kuiper Belt Objects and Jupiter Trojans will help to constrain models of solar system formation and dynamical evolution. Laboratory simulations of a possible thermal and irradiation history of these bodies were conducted on ice mixtures while monitoring their spectral properties. These simulations tested the hypothesis that the presence or absence of sulfur explains the two distinct visible near-infrared spectral groups observed in each population and that Trojans and KBOs share a common formation location. Mixed ices consisting of water, methanol, and ammonia, in mixtures both with and without hydrogen sulfide, were deposited and irradiated with 10 keV electrons. Deposition and initial irradiation were performed at 50 K to simulate formation at 20 au in the early solar system, then heated to Trojan-like temperatures and irradiated further. Finally, irradiation was concluded and resulting samples were observed during heating to room temperature. Results indicated that the presence of sulfur resulted in steeper spectral slopes. Heating through the 140–200 K range decreased the slopes and total reflectance for both mixtures. In addition, absorption features at 410, 620, and 900 nm appeared under irradiation, but only in the H2S-containing mixture. These features were lost with heating once irradiation was concluded. While the results reported here are consistent with the hypothesis, additional work is needed to address uncertainties and to simulate conditions not included in the present work.
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.
Skill Assessment of a Spectral Ocean-Atmosphere Radiative Model
Gregg, Watson, W.; Casey, Nancy W.
2009-01-01
Ocean phytoplankton, detrital material, and water absorb and scatter light spectrally. The Ocean- Atmosphere Spectral Irradiance Model (OASIM) is intended to provide surface irradiance over the oceans with sufficient spectral resolution to support ocean ecology, biogeochemistry, and heat exchange investigations, and of sufficient duration to support inter-annual and decadal investigations. OASIM total surface irradiance (integrated 200 nm to 4 microns) was compared to in situ data and three publicly available global data products at monthly 1-degree resolution. OASIM spectrally-integrated surface irradiance had root mean square (RMS) difference= 20.1 W/sq m (about 11%), bias=1.6 W/sq m (about 0.8%), regression slope= 1.01 and correlation coefficient= 0.89, when compared to 2322 in situ observations. OASIM had the lowest bias of any of the global data products evaluated (ISCCP-FD, NCEP, and ISLSCP 11), and the best slope (nearest to unity). It had the second best RMS, and the third best correlation coefficient. OASIM total surface irradiance compared well with ISCCP-FD (RMS= 20.7 W/sq m; bias=-11.4 W/sq m, r=0.98) and ISLSCP II (RMS =25.2 W/sq m; bias= -13.8 W/sq m; r=0.97), but less well with NCEP (RMS =43.0 W/sq m ;bias=-22.6 W/sq m; x=0.91). Comparisons of OASIM photosynthetically available radiation (PAR) with PAR derived from SeaWiFS showed low bias (-1.8 mol photons /sq m/d, or about 5%), RMS (4.25 mol photons /sq m/d ' or about 12%), near unity slope (1.03) and high correlation coefficient (0.97). Coupled with previous estimates of clear sky spectral irradiance in OASIM (6.6% RMS at 1 nm resolution), these results suggest that OASIM provides reasonable estimates of surface broadband and spectral irradiance in the oceans, and can support studies on ocean ecosystems, carbon cycling, and heat exchange.
Irradiation creep models - an overview
International Nuclear Information System (INIS)
Matthews, J.R.; Finnis, M.W.
1988-01-01
The modelling of irradiation creep is now highly developed but many of the basic processes underlying the models are poorly understood. A brief introduction is given to the theory of cascade interactions, point defect clustering and dislocation climb. The range of simple irradiation creep models is reviewed including: preferred nucleation of interstitial loops; preferred absorption of point defects by dislocations favourably orientated to an applied stress; various climb-enhanced glide and recovery mechanisms, and creep driven by internal stresses produced by irradiation growth. A range of special topics is discussed including: cascade effects; creep transients; structural and induced anisotropy; and the effect of impurities. The interplay between swelling and growth with thermal and irradiation creep is emphasized. A discussion is given on how irradiation creep theory should best be developed to assist the interpretation of irradiation creep observations and the requirements of reactor designers. (orig.)
[Modeling and Simulation of Spectral Polarimetric BRDF].
Ling, Jin-jiang; Li, Gang; Zhang, Ren-bin; Tang, Qian; Ye, Qiu
2016-01-01
Under the conditions of the polarized light, The reflective surface of the object is affected by many factors, refractive index, surface roughness, and so the angle of incidence. For the rough surface in the different wavelengths of light exhibit different reflection characteristics of polarization, a spectral polarimetric BRDF based on Kirchhof theory is proposee. The spectral model of complex refraction index is combined with refraction index and extinction coefficient spectral model which were got by using the known complex refraction index at different value. Then get the spectral model of surface roughness derived from the classical surface roughness measuring method combined with the Fresnel reflection function. Take the spectral model of refraction index and roughness into the BRDF model, then the spectral polarimetirc BRDF model is proposed. Compare the simulation results of the refractive index varies with wavelength, roughness is constant, the refraction index and roughness both vary with wavelength and origin model with other papers, it shows that, the spectral polarimetric BRDF model can show the polarization characteristics of the surface accurately, and can provide a reliable basis for the application of polarization remote sensing, and other aspects of the classification of substances.
SORCE SOLSTICE FUV Level 3 Solar Spectral Irradiance Daily Means V012
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...
SORCE SIM Level 3 Solar Spectral Irradiance Daily Means V020
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...
SORCE SIM Level 3 Solar Spectral Irradiance Daily Means V022
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...
Spectral Learning for Supervised Topic Models.
Ren, Yong; Wang, Yining; Zhu, Jun
2018-03-01
Supervised topic models simultaneously model the latent topic structure of large collections of documents and a response variable associated with each document. Existing inference methods are based on variational approximation or Monte Carlo sampling, which often suffers from the local minimum defect. Spectral methods have been applied to learn unsupervised topic models, such as latent Dirichlet allocation (LDA), with provable guarantees. This paper investigates the possibility of applying spectral methods to recover the parameters of supervised LDA (sLDA). We first present a two-stage spectral method, which recovers the parameters of LDA followed by a power update method to recover the regression model parameters. Then, we further present a single-phase spectral algorithm to jointly recover the topic distribution matrix as well as the regression weights. Our spectral algorithms are provably correct and computationally efficient. We prove a sample complexity bound for each algorithm and subsequently derive a sufficient condition for the identifiability of sLDA. Thorough experiments on synthetic and real-world datasets verify the theory and demonstrate the practical effectiveness of the spectral algorithms. In fact, our results on a large-scale review rating dataset demonstrate that our single-phase spectral algorithm alone gets comparable or even better performance than state-of-the-art methods, while previous work on spectral methods has rarely reported such promising performance.
Kärhä, Petri; Vaskuri, Anna; Mäntynen, Henrik; Mikkonen, Nikke; Ikonen, Erkki
2017-08-01
Spectral irradiance data are often used to calculate colorimetric properties, such as color coordinates and color temperatures of light sources by integration. The spectral data may contain unknown correlations that should be accounted for in the uncertainty estimation. We propose a new method for estimating uncertainties in such cases. The method goes through all possible scenarios of deviations using Monte Carlo analysis. Varying spectral error functions are produced by combining spectral base functions, and the distorted spectra are used to calculate the colorimetric quantities. Standard deviations of the colorimetric quantities at different scenarios give uncertainties assuming no correlations, uncertainties assuming full correlation, and uncertainties for an unfavorable case of unknown correlations, which turn out to be a significant source of uncertainty. With 1% standard uncertainty in spectral irradiance, the expanded uncertainty of the correlated color temperature of a source corresponding to the CIE Standard Illuminant A may reach as high as 37.2 K in unfavorable conditions, when calculations assuming full correlation give zero uncertainty, and calculations assuming no correlations yield the expanded uncertainties of 5.6 K and 12.1 K, with wavelength steps of 1 nm and 5 nm used in spectral integrations, respectively. We also show that there is an absolute limit of 60.2 K in the error of the correlated color temperature for Standard Illuminant A when assuming 1% standard uncertainty in the spectral irradiance. A comparison of our uncorrelated uncertainties with those obtained using analytical methods by other research groups shows good agreement. We re-estimated the uncertainties for the colorimetric properties of our 1 kW photometric standard lamps using the new method. The revised uncertainty of color temperature is a factor of 2.5 higher than the uncertainty assuming no correlations.
Iijima, Aya; Suzuki, Kazumi; Wakao, Shinji; Kawasaki, Norihiro; Usami, Akira
With a background of environmental problems and energy issues, it is expected that PV systems will be introduced rapidly and connected with power grids on a large scale in the future. For this reason, the concern to which PV power generation will affect supply and demand adjustment in electric power in the future arises and the technique of correctly grasping the PV power generation becomes increasingly important. The PV power generation depends on solar irradiance, temperature of a module and solar spectral irradiance. Solar spectral irradiance is distribution of the strength of the light for every wavelength. As the spectrum sensitivity of solar cell depends on kind of solar cell, it becomes important for exact grasp of PV power generation. Especially the preparation of solar spectral irradiance is, however, not easy because the observational instrument of solar spectral irradiance is expensive. With this background, in this paper, we propose a new method based on statistical pattern recognition for estimating the spectrum center which is representative index of solar spectral irradiance. Some numerical examples obtained by the proposed method are also presented.
Uncertainty Analysis of Spectral Irradiance Reference Standards Used for NREL Calibrations
Energy Technology Data Exchange (ETDEWEB)
Habte, A.; Andreas, A.; Reda, I.; Campanelli, M.; Stoffel, T.
2013-05-01
Spectral irradiance produced by lamp standards such as the National Institute of Standards and Technology (NIST) FEL-type tungsten halogen lamps are used to calibrate spectroradiometers at the National Renewable Energy Laboratory. Spectroradiometers are often used to characterize spectral irradiance of solar simulators, which in turn are used to characterize photovoltaic device performance, e.g., power output and spectral response. Therefore, quantifying the calibration uncertainty of spectroradiometers is critical to understanding photovoltaic system performance. In this study, we attempted to reproduce the NIST-reported input variables, including the calibration uncertainty in spectral irradiance for a standard NIST lamp, and quantify uncertainty for measurement setup at the Optical Metrology Laboratory at the National Renewable Energy Laboratory.
Shuttle SBUV (SSBUV) Solar Spectral Irradiance V008
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...
FIVE YEARS OF SYNTHESIS OF SOLAR SPECTRAL IRRADIANCE FROM SDID/SISA AND SDO /AIA IMAGES
Energy Technology Data Exchange (ETDEWEB)
Fontenla, J. M. [NorthWest Research Associates, Boulder, CO 80301 (United States); Codrescu, M. [Space Weather Prediction Center, National Oceanic and Atmospheric Administration, Boulder, CO 80305 (United States); Fedrizzi, M.; Fuller-Rowell, T. [Cooperative Institute for Research in Environmental Sciences, University of Colorado Boulder, Boulder, CO 80309 (United States); Hill, F. [National Solar Observatory, Boulder, CO 80303 (United States); Landi, E. [Department of Climate and Space Science and Engineering, University of Michigan, Ann Arbor, MI 48109 (United States); Woods, T., E-mail: johnf@digidyna.com [Laboratory for Atmospheric and Space Physics, University of Colorado Boulder, Boulder, CO 80303 (United States)
2017-01-01
In this paper we describe the synthetic solar spectral irradiance (SSI) calculated from 2010 to 2015 using data from the Atmospheric Imaging Assembly (AIA) instrument, on board the Solar Dynamics Observatory spacecraft. We used the algorithms for solar disk image decomposition (SDID) and the spectral irradiance synthesis algorithm (SISA) that we had developed over several years. The SDID algorithm decomposes the images of the solar disk into areas occupied by nine types of chromospheric and 5 types of coronal physical structures. With this decomposition and a set of pre-computed angle-dependent spectra for each of the features, the SISA algorithm is used to calculate the SSI. We discuss the application of the basic SDID/SISA algorithm to a subset of the AIA images and the observed variation occurring in the 2010–2015 period of the relative areas of the solar disk covered by the various solar surface features. Our results consist of the SSI and total solar irradiance variations over the 2010–2015 period. The SSI results include soft X-ray, ultraviolet, visible, infrared, and far-infrared observations and can be used for studies of the solar radiative forcing of the Earth’s atmosphere. These SSI estimates were used to drive a thermosphere–ionosphere physical simulation model. Predictions of neutral mass density at low Earth orbit altitudes in the thermosphere and peak plasma densities at mid-latitudes are in reasonable agreement with the observations. The correlation between the simulation results and the observations was consistently better when fluxes computed by SDID/SISA procedures were used.
Spectral distribution of the radiochemiluminescence from gamma-irradiated humic acid
International Nuclear Information System (INIS)
Goraczko, W.; Slawinski, J.; Staninski, K.
2008-01-01
This study was conducted to investigate radiochemiluminescence (RCL) spectra (340-650 nm), kinetics and absorption spectra of humic acids (HA) after their exposure of gamma-radiation (absorbed doses of 1-10 kGy, 60 Co) in model systems. The kinetics and spectral distribution of RCL were measured using the single photon counting method (SPC) and cut-off filters. Absorption spectra (range 240-800 nm) of irradiated solutions indicated that post-radiative degradation/polymerization processes take place in the HA changing their macromolecule or properties. The intensity of the delayed RCL was nonlinearly and suggested that complex radical formation mechanisms were still involved in the post-radiative reactions. (author)
Spectral distribution of the radiochemiluminescence from gamma-irradiated humic acid
Energy Technology Data Exchange (ETDEWEB)
Goraczko, W [Poznan University of Technology, Poznan (Poland). Faculty of Chemical Technology, Radio- and Photochemistry Department; Slawinski, J [Institute of Ecotechnology, Gniezno (Poland). State High Vocational School; Staninski, K [Adam Mickiewicz University, Poznan (Poland). Faculty of Chemistry, Department of Rare Earths
2008-09-15
This study was conducted to investigate radiochemiluminescence (RCL) spectra (340-650 nm), kinetics and absorption spectra of humic acids (HA) after their exposure of gamma-radiation (absorbed doses of 1-10 kGy, {sup 60}Co) in model systems. The kinetics and spectral distribution of RCL were measured using the single photon counting method (SPC) and cut-off filters. Absorption spectra (range 240-800 nm) of irradiated solutions indicated that post-radiative degradation/polymerization processes take place in the HA changing their macromolecule or properties. The intensity of the delayed RCL was nonlinearly and suggested that complex radical formation mechanisms were still involved in the post-radiative reactions. (author)
Liu, Qiang; Wan, Xiaoxia; Xie, Dehong
2014-06-01
The study presented here optimizes several steps in the spectral printer modeling workflow based on a cellular Yule-Nielsen spectral Neugebauer (CYNSN) model. First, a printer subdividing method was developed that reduces the number of sub-models while maintaining the maximum device gamut. Second, the forward spectral prediction accuracy of the CYNSN model for each subspace of the printer was improved using back propagation artificial neural network (BPANN) estimated n values. Third, a sequential gamut judging method, which clearly reduced the complexity of the optimal sub-model and cell searching process during printer backward modeling, was proposed. After that, we further modified the use of the modeling color metric and comprehensively improved the spectral and perceptual accuracy of the spectral printer model. The experimental results show that the proposed optimization approaches provide obvious improvements in aspects of the modeling accuracy or efficiency for each of the corresponding steps, and an overall improvement of the optimized spectral printer modeling workflow was also demonstrated.
International Nuclear Information System (INIS)
Assaf, J.
2009-07-01
Mathematical model for the RMS noise of JFET transistor has been realized. Fitting the model according to the experimental results gives the noise spectral densities values. Best fitting was for the model of three noise sources and real preamplifier transfer function. After gamma irradiation, an additional and important noise sources appeared and two point defects are estimated through the fitting process. (author)
Energy Technology Data Exchange (ETDEWEB)
Canada, J.; Maj, A. [Departamento de Termodinamica Aplicada, Universidad Politecnica de Valencia, Camino de Vera, s/n. 46022 Valencia (Spain); Utrillas, M.P.; Martinez-Lozano, J.A.; Pedros, R.; Gomez-Amo, J.L. [Departamento de Fisica de la Tierra y Termodinamica, Facultat de Fisica, Universitat de Valencia, 46100 Burjassot (Valencia) (Spain)
2007-10-15
An automatic global and direct solar spectral irradiance system has been designed based on two LICOR spectro radiometers equipped with fibre optics and remote cosine sensors. To measure direct irradiance a sun tracker based on step motors has been developed. The whole system is autonomous and works continuously. From the measurements provided by this system a spectral irradiance database in the 330-1100 nm range has been created. This database contains normal direct and global horizontal irradiances as well as diffuse irradiance on a horizontal plane, together with total atmospheric optical thickness and aerosol optical depth. (author)
Deployment and early results from the CanSIM (Canadian Solar Spectral Irradiance Meter) network
Tatsiankou, Viktar; Hinzer, Karin; Schriemer, Henry; McVey-White, Patrick; Beal, Richard
2017-09-01
Three of seven stations have been deployed as part of the Canadian Solar Spectral Irradiance (CanSIM) network situated in Ottawa, Varennes and Egbert to measure long term spectral variation of the direct normal (DNI) and global horizontal irradiances (GHI) across the country. Every station is equipped with a solar tracker, SolarSIM-D2+, SolarSIM-G+, and SR20 pyranometer, reporting the spectral DNI, GHI, diffuse horizontal irradiance (DHI) and aerosol optical depth in the 280-4000 nm range, broadband DNI, GHI, and DHI, atmospheric total column ozone and water vapour amounts. The spectral GHI as measured by the SolarSIM-G+ was within 5% as compared to EKO MS-700 spectroradiometer in 350-1050 nm range on 17 March 2017. The difference in the GHI as reported by SolarSIM-G+ and SR20 pyranometer from all stations was within 2% on 14 April 2017. Furthermore, on this day, the daily GHI sum for the Ottawa, Varennes, and Egbert stations was 7.01, 6.95, and 7.11 kWh/m2, respectively, while the daily DNI sum was 10.65, 10.86, 10.04 kWh/m2, respectively.
Gap timing and the spectral timing model.
Hopson, J W
1999-04-01
A hypothesized mechanism underlying gap timing was implemented in the Spectral Timing Model [Grossberg, S., Schmajuk, N., 1989. Neural dynamics of adaptive timing and temporal discrimination during associative learning. Neural Netw. 2, 79-102] , a neural network timing model. The activation of the network nodes was made to decay in the absence of the timed signal, causing the model to shift its peak response time in a fashion similar to that shown in animal subjects. The model was then able to accurately simulate a parametric study of gap timing [Cabeza de Vaca, S., Brown, B., Hemmes, N., 1994. Internal clock and memory processes in aminal timing. J. Exp. Psychol.: Anim. Behav. Process. 20 (2), 184-198]. The addition of a memory decay process appears to produce the correct pattern of results in both Scalar Expectancy Theory models and in the Spectral Timing Model, and the fact that the same process should be effective in two such disparate models argues strongly that process reflects a true aspect of animal cognition.
Wilbert, Stefan; Kleindiek, Stefan; Nouri, Bijan; Geuder, Norbert; Habte, Aron; Schwandt, Marko; Vignola, Frank
2016-05-01
Concentrating solar power projects require accurate direct normal irradiance (DNI) data including uncertainty specifications for plant layout and cost calculations. Ground measured data are necessary to obtain the required level of accuracy and are often obtained with Rotating Shadowband Irradiometers (RSI) that use photodiode pyranometers and correction functions to account for systematic effects. The uncertainty of Si-pyranometers has been investigated, but so far basically empirical studies were published or decisive uncertainty influences had to be estimated based on experience in analytical studies. One of the most crucial estimated influences is the spectral irradiance error because Si-photodiode-pyranometers only detect visible and color infrared radiation and have a spectral response that varies strongly within this wavelength interval. Furthermore, analytic studies did not discuss the role of correction functions and the uncertainty introduced by imperfect shading. In order to further improve the bankability of RSI and Si-pyranometer data, a detailed uncertainty analysis following the Guide to the Expression of Uncertainty in Measurement (GUM) has been carried out. The study defines a method for the derivation of the spectral error and spectral uncertainties and presents quantitative values of the spectral and overall uncertainties. Data from the PSA station in southern Spain was selected for the analysis. Average standard uncertainties for corrected 10 min data of 2 % for global horizontal irradiance (GHI), and 2.9 % for DNI (for GHI and DNI over 300 W/m²) were found for the 2012 yearly dataset when separate GHI and DHI calibration constants were used. Also the uncertainty in 1 min resolution was analyzed. The effect of correction functions is significant. The uncertainties found in this study are consistent with results of previous empirical studies.
Spectral properties in supersymmetric matrix models
International Nuclear Information System (INIS)
Boulton, Lyonell; Garcia del Moral, Maria Pilar; Restuccia, Alvaro
2012-01-01
We formulate a general sufficiency criterion for discreteness of the spectrum of both supersymmmetric and non-supersymmetric theories with a fermionic contribution. This criterion allows an analysis of Hamiltonians in complete form rather than just their semiclassical limits. In such a framework we examine spectral properties of various (1+0) matrix models. We consider the BMN model of M-theory compactified on a maximally supersymmetric pp-wave background, different regularizations of the supermembrane with central charges and a non-supersymmetric model comprising a bound state of N D2 with m D0. While the first two examples have a purely discrete spectrum, the latter has a continuous spectrum with a lower end given in terms of the monopole charge.
Szilagyi, John; Parchamy, Homaira; Masnavi, Majid; Richardson, Martin
2017-01-01
The absolute spectral irradiances of laser-plasmas produced from planar zinc targets are determined over a wavelength region of 150 to 250 nm. Strong spectral radiation is generated using 60 ns full-width-at-half-maximum, 1.0 μm wavelength laser pulses with incident laser intensities as low as ˜5 × 108 W cm-2. A typical radiation conversion efficiency of ˜2%/2πsr is measured. Numerical calculations using a comprehensive radiation-hydrodynamics model reveal the strong experimental spectra to originate mainly from 3d94s4p-3d94s2, 3d94s4d-3d94s4p, and 3d94p-3d94s, 3d94d-3d94p unresolved-transition arrays in singly and doubly ionized zinc, respectively.
Modelling microstructural evolution under irradiation
International Nuclear Information System (INIS)
Tikare, V.
2015-01-01
Microstructural evolution of materials under irradiation is characterised by some unique features that are not typically present in other application environments. While much understanding has been achieved by experimental studies, the ability to model this microstructural evolution for complex materials states and environmental conditions not only enhances understanding, it also enables prediction of materials behaviour under conditions that are difficult to duplicate experimentally. Furthermore, reliable models enable designing materials for improved engineering performance for their respective applications. Thus, development and application of mesoscale microstructural model are important for advancing nuclear materials technologies. In this chapter, the application of the Potts model to nuclear materials will be reviewed and demonstrated, as an example of microstructural evolution processes. (author)
Witteborn, Fred C.; Cohen, Martin; Bregman, Jess D.; Wooden, Diane; Heere, Karen; Shirley, Eric L.
1998-01-01
Infrared spectra of two celestial objects frequently used as flux standards are calibrated against an absolute laboratory flux standard at a spectral resolving power of 100 to 200. The spectrum of the K1.5III star, alpha Boo, is measured from 3 microns to 30 microns and that of the C-type asteroid, 1 Ceres, from 5 microns to 30 microns. While these 'standard' spectra do not have the apparent precision of those based on calculated models, they do not require the assumptions involved in theoretical models of stars and asteroids. Specifically they provide a model-independent means of calibrating celestial flux in the spectral range from 12 microns to 30 microns where accurate absolute photometry is not available. The agreement found between the spectral shapes of alpha Boo and Ceres based on laboratory standards, and those based on observed ratios to alpha CMa (Sirius) and alpha Lyr (Vega), flux calibrated by theoretical modeling of these hot stars strengthens our confidence in the applicability of the stellar models as primary irradiance standards.
International Nuclear Information System (INIS)
Schneider, W.
1986-10-01
This is a report on the planning and results of neutron monitoring in the capsules of the Juelich steel irradiation for the research project on component safety (FKS). The table of results and their discussion is provided specifically for the spectral positions (for characterising the neutron spectrum) in each of the types of irradiation capsules used. The results are given for the reaction rates of the neutron measurement reactions used (activation or fission reactions), for the neutron flux densities and fluxes derived from them related to the actual or at least plausible neutron spectra and finally for the radiation damage (or exposure) of the irradiated material calculated from them, expressed as the atomic displacement figure (dpa) and its percentage in sections of the neutron spectrum. (orig.) [de
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
Fabrication and operation of HFIR-MFE RB* spectrally tailored irradiation capsules
International Nuclear Information System (INIS)
Longest, A.W.; Pawel, J.E.; Heatherly, D.W.; Sitterson, R.G.; Wallace, R.L.
1993-01-01
Fabrication and operation of four HFIR-MFE RB * capsules (60, 200, 330, and 400 degrees C) to accommodate MFE specimens previously irradiated in spectrally tailored experiments in the ORR are proceeding satisfactorily. With the exception of the 60 degrees C capsule, where the test specimens were in direct contact with the reactor cooling water, specimen temperatures (monitored by 21 thermocouples) are controlled by varying the thermal conductance of a thin gap region between the specimen holder outer sleeve and containment tube. Irradiation of the 60 and 330 degrees C capsules, which started on July 17, 1990, was completed on November 14, 1992, after 24 cycles of irradiation to an incremental damage level of approximately 10.9 displacements per atom (dpa). Assembly of the follow-up 200 and 400 degrees C capsules was completed in November 1992, and their planned 20-cycle irradiation to approximately 9.1 incremental dpa was started on November 21, 1992. As of February 11, 1993, the 200 and 400 degrees C capsules had successfully completed three cycles of irradiation to approximately 1.4 incremental dpa
Spectral modeling of radiation in combustion systems
Pal, Gopalendu
Radiation calculations are important in combustion due to the high temperatures encountered but has not been studied in sufficient detail in the case of turbulent flames. Radiation calculations for such problems require accurate, robust, and computationally efficient models for the solution of radiative transfer equation (RTE), and spectral properties of radiation. One more layer of complexity is added in predicting the overall heat transfer in turbulent combustion systems due to nonlinear interactions between turbulent fluctuations and radiation. The present work is aimed at the development of finite volume-based high-accuracy thermal radiation modeling, including spectral radiation properties in order to accurately capture turbulence-radiation interactions (TRI) and predict heat transfer in turbulent combustion systems correctly and efficiently. The turbulent fluctuations of temperature and chemical species concentrations have strong effects on spectral radiative intensities, and TRI create a closure problem when the governing partial differential equations are averaged. Recently, several approaches have been proposed to take TRI into account. Among these attempts the most promising approaches are the probability density function (PDF) methods, which can treat nonlinear coupling between turbulence and radiative emission exactly, i.e., "emission TRI". The basic idea of the PDF method is to treat physical variables as random variables and to solve the PDF transport equation stochastically. The actual reacting flow field is represented by a large number of discrete stochastic particles each carrying their own random variable values and evolving with time. The mean value of any function of those random variables, such as the chemical source term, can be evaluated exactly by taking the ensemble average of particles. The local emission term belongs to this class and thus, can be evaluated directly and exactly from particle ensembles. However, the local absorption term
Reconstruction of solar spectral surface UV irradiances using radiative transfer simulations.
Lindfors, Anders; Heikkilä, Anu; Kaurola, Jussi; Koskela, Tapani; Lakkala, Kaisa
2009-01-01
UV radiation exerts several effects concerning life on Earth, and spectral information on the prevailing UV radiation conditions is needed in order to study each of these effects. In this paper, we present a method for reconstruction of solar spectral UV irradiances at the Earth's surface. The method, which is a further development of an earlier published method for reconstruction of erythemally weighted UV, relies on radiative transfer simulations, and takes as input (1) the effective cloud optical depth as inferred from pyranometer measurements of global radiation (300-3000 nm); (2) the total ozone column; (3) the surface albedo as estimated from measurements of snow depth; (4) the total water vapor column; and (5) the altitude of the location. Reconstructed daily cumulative spectral irradiances at Jokioinen and Sodankylä in Finland are, in general, in good agreement with measurements. The mean percentage difference, for instance, is mostly within +/-8%, and the root mean square of the percentage difference is around 10% or below for wavelengths over 310 nm and daily minimum solar zenith angles (SZA) less than 70 degrees . In this study, we used pseudospherical radiative transfer simulations, which were shown to improve the performance of our method under large SZA (low Sun).
Solar Spectral Irradiance Reconstruction over 9 Millennia from a Composite 14C and 10Be Series
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.
Modelling irradiation effect of EUROFER
International Nuclear Information System (INIS)
Boutard, J.-L.; Dudarev, S.; Victoria, M.
2006-01-01
In fusion power reactor, the properties that controlled the behaviour of materials are affected at the atom scale: (i) the crystalline structure is locally destroyed where a displacement cascade occurs, (ii) the chemical bond is affected by transmutation products such as He and H, (iii) an radiation induced microstructure will take place due the diffusion of these point defects and impurities EFDA has launched a programme since 2002 to develop and validate modelling tools to predict the radiation effects in the reference ferritic martensitic steel Eurofer. Up to now, the effort has been devoted (i) to validate the multi-scale modelling approach based on ab-initio energetics map of point defects and He, (iii) to develop inter-atomic potentials for Molecular Dynamics simulation of displacement cascades and dislocation dynamics. Formation and migration energies and diffusion mechanisms of small vacancy (n< ) and interstitial clusters (n< ) were computed with the ab-initio code SIESTA and used to successfully predict via Kinetic Monte Carlo the experimental recovery stages of radiation damage in ultra high purity Fe. A complete He and point defect energetics mapping was ab-initio determined in Fe-C and used to reproduce via Rate Theory He-desorption from pre-implanted specimens. A developed '' magnetic '' potential is capable of transferring the magnetic properties of Fe due to the 3d-electron correlation to the scale of the Molecular Dynamics. An inter-atomic potential is being developed to reproduce the thermodynamics of the Fe-Cr system. The program will now be devoted (i) to develop atom-scale reference kinetic methods to predict the phase - stability of the Fe-Cr thermally and under irradiation (ii) to predict at the atom scale the core structure and dynamics of screw dislocation and their collective behaviour at the meso-scale, using Discrete Dislocation Dynamics (iii) to validate at the relevant scale using the multi-beam CEA-CNRS facility JANNUS. JANNUS allows
International Nuclear Information System (INIS)
Koussa, Mustapha; Saheb-Koussa, Djohra; Hadji, Seddik
2017-01-01
In this work, models are presented that, under cloudless atmosphere conditions, calculate solar spectral normal direct and horizontal diffuse irradiance. Based on different monochromatic transmission factors related to the main constituents of the atmosphere, the models evaluate the spectral irradiance between 0.29 and 4.0 μm. Absorption by water vapor, uniformly mixed gas, and ozone are considered as well as scattering by the atmospheric aerosols. Based on the equations relative to each one of the two retained models, a MATLAB program is developed to evaluate the spectral distribution of each solar irradiance component. Hence, the geographical coordinates of the site, and the monochromatic distribution of the extraterrestrial irradiance are used as input data. From three-year data measurement records made in Bouzareah site (temperate climate), thirty eight days characterized by a clear sky state have been selected from over different months of the year and the corresponding main meteorological parameters used as input parameters. So, because only the five-minute broadband data measurements are available, the modified numerical trapeze method is used to integrate the monochromatic curve values related to each solar irradiance component. Consequently, the precipitable water vapor amount, the Angstrom and Linke turbidity factors are evaluated and a multi-linear correlation relating the Linke turbidity factor to the precipitable water vapor and the Angstrom turbidity coefficient is established. Hence, according to the mean values of Linke and Angstrom turbidity factors and those of the precipitable water vapor, the site of Bouzareah is classified as a rural site. So, the effect of the main constituents of the atmosphere on the spectral distribution of solar irradiance is discussed and, it is also observed that the aerosol amount contained in the atmosphere affects most both of the diffuse and direct solar irradiance amount than that of the horizontal and inclined
Liu, Yan; Hu, LiWen; Wang, Fang; Gao, YanYan; Zheng, Yang; Wang, Yu; Liu, Yang
2016-01-01
To investigate the angular distributions of UVA, UVB, and effective UV for erythema and vitamin D (vitD) synthesis, the UV spectral irradiances were measured at ten inclined angles (from 0° to 90°) and seven azimuths (from 0° to 180°) at solar elevation angle (SEA) that ranged from 18.8° to 80° in Shanghai (31.22° N, 121.55° E) under clear sky and the albedo of ground was 0.1. The results demonstrated that in the mean azimuths and with the back to the sun, the UVA, UVB, and erythemally and vitD-weighted irradiances increased with the inclined angles and an increase in SEA. When facing toward the sun at 0°-60° inclined angles, the UVA first increased and then decreased with an increase in SEA; at other inclined angles, the UVA increased with SEA. At 0°-40° inclined angles, the UVB and erythemally and vitD-weighted irradiances first increased and then decreased with an increase in SEA, and their maximums were achieved at SEA 68.7°; at other inclined angles, the above three irradiances increased with an increase in SEA. The maximum UVA, UVB, and erythemally and vitD-weighted irradiances were achieved at an 80° inclined angle at SEA 80° (the highest in our measurements); the cumulative exposure of the half day achieved the maximum at a 60° inclined angle, but not on the horizontal. This study provides support for the assessment of human skin sun exposure.
Satellite estimation of surface spectral ultraviolet irradiance using OMI data in East Asia
Lee, H.; Kim, J.; Jeong, U.
2017-12-01
Due to a strong influence to the human health and ecosystem environment, continuous monitoring of the surface ultraviolet (UV) irradiance is important nowadays. The amount of UVA (320-400 nm) and UVB (290-320 nm) radiation at the Earth surface depends on the extent of Rayleigh scattering by atmospheric gas molecules, the radiative absorption by ozone, radiative scattering by clouds, and both absorption and scattering by airborne aerosols. Thus advanced consideration of these factors is the essential part to establish the process of UV irradiance estimation. Also UV index (UVI) is a simple parameter to show the strength of surface UV irradiance, therefore UVI has been widely utilized for the purpose of UV monitoring. In this study, we estimate surface UV irradiance at East Asia using realistic input based on OMI Total Ozone and reflectivity, and then validate this estimated comparing to UV irradiance from World Ozone and Ultraviolet Radiation Data Centre (WOUDC) data. In this work, we also try to develop our own retrieval algorithm for better estimation of surface irradiance. We use the Vector Linearized Discrete Ordinate Radiative Transfer (VLIDORT) model version 2.6 for our UV irradiance calculation. The input to the VLIDORT radiative transfer calculations are the total ozone column (TOMS V7 climatology), the surface albedo (Herman and Celarier, 1997) and the cloud optical depth. Based on these, the UV irradiance is calculated based on look-up table (LUT) approach. To correct absorbing aerosol, UV irradiance algorithm added climatological aerosol information (Arola et al., 2009). The further study, we analyze the comprehensive uncertainty analysis based on LUT and all input parameters.
Survey of the spectral irradiance distribution of fluorescent tubes for solaria
International Nuclear Information System (INIS)
Johnsen, B.; Hannevik, M.
1993-01-01
The report describes a systematic mapping of the spectral irradiance distribution of typical fluorescent tubes, emitting ultraviolet radiation (UVR). The spectra were multiplied with biological action curves for assessing their potential for acute harmful effects. Comparing values of effective irradiance revealed a difference by a factor of ten between tubes for cosmetic UVR-treatment. Comparing spectra of the strongest cosmetic types with the spectrum of a typical tube for medical UVR-treatment revealed another factor of ten in effective irradiance. Spectra of typical cosmetic solarium tubes and natural sun at summer in Oslo are shown to be closely related in the UV-region, thereby justifying the term artificial sunlamps. Threshold limit values and action curves, as expressed in the former Norwegian solarium prescriptions from 1983 and the CENELEC standard for classifying UVR-emitting appliance, were compared. Calculations have shown that an adoption of the CENELEC threshold limit values will be more restrictive on the short-wave UV-region, while they generally will be similar, or a bit less restrictive on the longwave UV-region. 3 refs., 45 figs., 6 tabs
A model for phase stability under irradiation
International Nuclear Information System (INIS)
Abromeit, C.
The combination of two theoretical models leads to modified criteria of stability of precipitates under heavy particle irradiation. The size of existing or under irradiation newly formed precipitates is limited by a stable radius. Precipitate surface energy effects are included in a consistent manner
International Nuclear Information System (INIS)
Artyukhov, V.G.; Sviridova, Eh.V.
1977-01-01
Study of spectral characteristics of oxyhemoglobin solutions (0.5 x 10 -5 M) γ-irradiated in the presence of serotonin (5 x 10 -5 M) has demonstrated that serotonin has a protective action on oxyhemoglobin. The protective effect of serotonin was also observed in relation to irradiated oxyhemoglobin solutions incubated for 30 min at 45 deg C. It is suggested that the protective action of serotonin may be due to the formation of H 2 O 2 /serotonin complex
Description and availability of the SMARTS spectral model for photovoltaic applications
Myers, Daryl R.; Gueymard, Christian A.
2004-11-01
Limited spectral response range of photocoltaic (PV) devices requires device performance be characterized with respect to widely varying terrestrial solar spectra. The FORTRAN code "Simple Model for Atmospheric Transmission of Sunshine" (SMARTS) was developed for various clear-sky solar renewable energy applications. The model is partly based on parameterizations of transmittance functions in the MODTRAN/LOWTRAN band model family of radiative transfer codes. SMARTS computes spectra with a resolution of 0.5 nanometers (nm) below 400 nm, 1.0 nm from 400 nm to 1700 nm, and 5 nm from 1700 nm to 4000 nm. Fewer than 20 input parameters are required to compute spectral irradiance distributions including spectral direct beam, total, and diffuse hemispherical radiation, and up to 30 other spectral parameters. A spreadsheet-based graphical user interface can be used to simplify the construction of input files for the model. The model is the basis for new terrestrial reference spectra developed by the American Society for Testing and Materials (ASTM) for photovoltaic and materials degradation applications. We describe the model accuracy, functionality, and the availability of source and executable code. Applications to PV rating and efficiency and the combined effects of spectral selectivity and varying atmospheric conditions are briefly discussed.
DEFF Research Database (Denmark)
LASSEN, C.; PLOUG, H.; JØRGENSEN, BB
1992-01-01
in sediments was measured at 100-mu-m spatial resolution. Light was available for photosynthesis near the sediment surface at a higher intensity and a different spectral composition than could be expected from the illumination. By the combination of oxygen microelectrodes and the present fibre......The manufacturing of a new spherical fibreoptic microsensor is described. The microsensor measures scalar irradiance, i.e. the spherically integrated light at a point in space. The light collector of the probe was a 70-mu-m diffusing sphere cast on the tip of a 125-mu-m wide optical fibre tapered......-optic microsensor it is now possible to study the depth distribution of microbenthic photosynthesis in relation to the available photosynthetically active radiation at less-than-or-equal-to 100-mu-m resolution....
Accurate measurements of solar spectral irradiance between 4000-10000 cm-1
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.
Modelling property changes in graphite irradiated at changing irradiation temperature
CSIR Research Space (South Africa)
Kok, S
2011-01-01
Full Text Available A new method is proposed to predict the irradiation induced property changes in nuclear; graphite, including the effect of a change in irradiation temperature. The currently used method; to account for changes in irradiation temperature, the scaled...
International Nuclear Information System (INIS)
Noè, N.; Eccher, T.; Bonini, L.
1997-01-01
Four clones of Malus domestica cv. Golden Delicious - namely Smoothee, Crielaard, Reinders and Golden B - were cultured in vitro from single-node microcuttings placed on solid medium under irradiance (PPFD) of 50 micromol m -2 s -1 . After 9 months an average shoot proliferation of 5.3 was achieved; Crielaard showed the highest rate (7.1), followed Golden B (5.4), Smoothee and Reinders (4.4). Proliferating shoots were then exposed to higher PPFD (80 micromol m -2 s -1 ) and different spectral composition of radiation using PMMA-B and PMMA-R/FR filters. High PPFD decreased the average proliferation rate to 4.5, in particular in Crielaard and Golden B, while it increased proliferation in Reinders. When a PMMA-R/FR filter was interposed, the mean proliferation rate slightly increased. PMMA-B filters decreased the overall proliferation rate to 3.0; only in Crielaard it was increased, but shoots were very small. Thus PPFD and spectral composition influenced in vitro shoot proliferation and growth and the responses were different among the clones. (author)
8 years of Solar Spectral Irradiance Observations from the ISS with the SOLAR/SOLSPEC Instrument
Damé, L.; Bolsée, D.; Meftah, M.; Irbah, A.; Hauchecorne, A.; Bekki, S.; Pereira, N.; Cessateur, G.; Marchand, M.; Thiéblemont, R.; Foujols, T.
2016-12-01
Accurate measurements of Solar Spectral Irradiance (SSI) are of primary importance for a better understanding of solar physics and of the impact of solar variability on climate (via Earth's atmospheric photochemistry). The acquisition of a top of atmosphere reference solar spectrum and of its temporal and spectral variability during the unusual solar cycle 24 is of prime interest for these studies. These measurements are performed since April 2008 with the SOLSPEC spectro-radiometer from the far ultraviolet to the infrared (166 nm to 3088 nm). This instrument, developed under a fruitful LATMOS/BIRA-IASB collaboration, is part of the Solar Monitoring Observatory (SOLAR) payload, externally mounted on the Columbus module of the International Space Station (ISS). The SOLAR mission, with its actual 8 years duration, will cover almost the entire solar cycle 24. We present here the in-flight operations and performances of the SOLSPEC instrument, including the engineering corrections, calibrations and improved know-how procedure for aging corrections. Accordingly, a SSI reference spectrum from the UV to the NIR will be presented, together with its UV variability, as measured by SOLAR/SOLSPEC. Uncertainties on these measurements and comparisons with other instruments will be briefly discussed.
Chen, Sheng-Bo; Wang, Jing-Ran; Guo, Peng-Ju; Wang, Ming-Chang
2014-09-01
The Moon may be considered as the frontier base for the deep space exploration. The spectral analysis is one of the key techniques to determine the lunar surface rock and mineral compositions. But the lunar topographic relief is more remarkable than that of the Earth. It is necessary to conduct the topographic correction for lunar spectral data before they are used to retrieve the compositions. In the present paper, a lunar Sandmeier model was proposed by considering the radiance effect from the macro and ambient topographic relief. And the reflectance correction model was also reduced based on the Sandmeier model. The Spectral Profile (SP) data from KAGUYA satellite in the Sinus Iridum quadrangle was taken as an example. And the digital elevation data from Lunar Orbiter Laser Altimeter are used to calculate the slope, aspect, incidence and emergence angles, and terrain-viewing factor for the topographic correction Thus, the lunar surface reflectance from the SP data was corrected by the proposed model after the direct component of irradiance on a horizontal surface was derived. As a result, the high spectral reflectance facing the sun is decreased and low spectral reflectance back to the sun is compensated. The statistical histogram of reflectance-corrected pixel numbers presents Gaussian distribution Therefore, the model is robust to correct lunar topographic effect and estimate lunar surface reflectance.
Validation of spectral gas radiation models under oxyfuel conditions
Energy Technology Data Exchange (ETDEWEB)
Becher, Johann Valentin
2013-05-15
Combustion of hydrocarbon fuels with pure oxygen results in a different flue gas composition than combustion with air. Standard computational-fluid-dynamics (CFD) spectral gas radiation models for air combustion are therefore out of their validity range in oxyfuel combustion. This thesis provides a common spectral basis for the validation of new spectral models. A literature review about fundamental gas radiation theory, spectral modeling and experimental methods provides the reader with a basic understanding of the topic. In the first results section, this thesis validates detailed spectral models with high resolution spectral measurements in a gas cell with the aim of recommending one model as the best benchmark model. In the second results section, spectral measurements from a turbulent natural gas flame - as an example for a technical combustion process - are compared to simulated spectra based on measured gas atmospheres. The third results section compares simplified spectral models to the benchmark model recommended in the first results section and gives a ranking of the proposed models based on their accuracy. A concluding section gives recommendations for the selection and further development of simplified spectral radiation models. Gas cell transmissivity spectra in the spectral range of 2.4 - 5.4 {mu}m of water vapor and carbon dioxide in the temperature range from 727 C to 1500 C and at different concentrations were compared in the first results section at a nominal resolution of 32 cm{sup -1} to line-by-line models from different databases, two statistical-narrow-band models and the exponential-wide-band model. The two statistical-narrow-band models EM2C and RADCAL showed good agreement with a maximal band transmissivity deviation of 3 %. The exponential-wide-band model showed a deviation of 6 %. The new line-by-line database HITEMP2010 had the lowest band transmissivity deviation of 2.2% and was therefore recommended as a reference model for the
Energy Technology Data Exchange (ETDEWEB)
Zeyada, H.M., E-mail: hzeyada@gmail.com [Department of Physics, Faculty of Science at New Damietta, University of Damietta, 34517 (Egypt); Youssif, M.I.; El-Ghamaz, N.A. [Department of Physics, Faculty of Science at New Damietta, University of Damietta, 34517 (Egypt); Aboderbala, M.E.O. [Department of Physics, Faculty of Science at New Damietta, University of Damietta, 34517 (Egypt); Department of Physics, Faculty of Science, AlJabl Al Gharbi University (Libya)
2017-02-01
Optical properties of pristine and UV irradiated Rose Bengal (RB) films have been investigated using transmittance and reflectance methods. The refractive index(n) and extinction coefficient (k) have been calculated from the absolute values of transmission and reflection spectrum. Single oscillator parameters and Drude model of free carrier absorption have been applied for analysis of the refractive index dispersion. Within the frame work of the band-to-band electron transitions theory; the fundamental absorption edge data were analyzed. Our results suggest that thickness of RB films has no effect on the absorption or the refractive indices in the investigated thicknesses range and within the experimental error. Structural transformation of films from amorphous to polycrystalline has been observed upon UV irradiation. Accordingly, the decreases of all of the absorption coefficient, the energy gap and the refractive index of RB films have been detected. Furthermore, the dependence of the optical functions on UV exposure times has been discussed based on the spectral distribution of the dielectric constant.
DEFF Research Database (Denmark)
PLOUG, H.; LASSEN, C.; JØRGENSEN, BB
1993-01-01
for photosynthesis and spectral scalar irradiance, E0, were measured directly in the sediment at a spatial resolution of 0.1 mm by the use of oxygen and light microsensors. The action spectrum for the diatoms was similar to the attenuation spectrum of the scalar irradiance, K0, in the diatom layer with Chl...... to calculate the spectral quality for photosynthesis of the 400-700 nm light to which the two populations were exposed. This spectral quality was compared to that of the light incident on the sediment surface. Due to preferential extinction of wavelengths, at which their photosynthetically active pigments had...... populations, and that total light intensity and the chemical microenvironment are probably more important factors....
Validation of buoyancy driven spectral tensor model using HATS data
DEFF Research Database (Denmark)
Chougule, A.; Mann, Jakob; Kelly, Mark C.
2016-01-01
We present a homogeneous spectral tensor model for wind velocity and temperature fluctuations, driven by mean vertical shear and mean temperature gradient. Results from the model, including one-dimensional velocity and temperature spectra and the associated co-spectra, are shown in this paper....... The model also reproduces two-point statistics, such as coherence and phases, via cross-spectra between two points separated in space. Model results are compared with observations from the Horizontal Array Turbulence Study (HATS) field program (Horst et al. 2004). The spectral velocity tensor in the model...
MODELING SPECTRAL AND TEMPORAL MASKING IN THE HUMAN AUDITORY SYSTEM
DEFF Research Database (Denmark)
Dau, Torsten; Jepsen, Morten Løve; Ewert, Stephan D.
2007-01-01
An auditory signal processing model is presented that simulates psychoacoustical data from a large variety of experimental conditions related to spectral and temporal masking. The model is based on the modulation filterbank model by Dau et al. [J. Acoust. Soc. Am. 102, 2892-2905 (1997)] but inclu......An auditory signal processing model is presented that simulates psychoacoustical data from a large variety of experimental conditions related to spectral and temporal masking. The model is based on the modulation filterbank model by Dau et al. [J. Acoust. Soc. Am. 102, 2892-2905 (1997...... was tested in conditions of tone-in-noise masking, intensity discrimination, spectral masking with tones and narrowband noises, forward masking with (on- and off-frequency) noise- and pure-tone maskers, and amplitude modulation detection using different noise carrier bandwidths. One of the key properties...
The cloud effects on UV irradiance modeled in Antarctica
International Nuclear Information System (INIS)
Rafanelli, C.; Anav, A.; Ciattaglia, L.; Di Menno, I.; Di Menno, M.; Araujo, J.; Ochoa, H.; Rodriguez, H.
2004-01-01
Full text: The measurement of solar UV radiation in Antarctica is very important in order to obtain information about Ozone level, and many spectro radiometers are installed in the area to perform this task. Usually, their use is very difficult in harsh environment like Southern polar regions, and several multichannel radiometers have been installed. The evaluation of the irradiance and total ozone levels are done using analytical models. A new semi-analytical method to estimate the solar UV irradiance at ground, named WL4UV, was developed. Using spectral irradiance values at 4 selected wavelengths in the UV-B and UV-A regions (305, 320, 340 and 380 nm), the solar UV irradiance at ground is evaluated with low percent of error. The applicability of the method has been tested for clear sky but such conditions are not common in Antarctic. This work investigate the applicability of the WL4UV model under cloudy sky conditions. The 4 irradiance necessary for the model were selected from spectrophotometer Brewer measurements carried out in the Argentinean Belgrano II base (77 degrees 52' S and 34 degrees 38' W). Other tests using spectrophotometers, Brewer and SUV 100, located in Ushuaia, (54 degrees 50' S and 68 degrees 19' W), were also too. This project was funded by the PNRA, IIA-DNA and CADIC for funding and supporting the activities. They thank also all the Brewer operators that in these years spent their time in the management of the instrument. Last but not the least they thank all IIA-DNA personnel for the professional help they put in carrying out the activities in all these years. (author)
Chebyshev super spectral viscosity method for a fluidized bed model
International Nuclear Information System (INIS)
Sarra, Scott A.
2003-01-01
A Chebyshev super spectral viscosity method and operator splitting are used to solve a hyperbolic system of conservation laws with a source term modeling a fluidized bed. The fluidized bed displays a slugging behavior which corresponds to shocks in the solution. A modified Gegenbauer postprocessing procedure is used to obtain a solution which is free of oscillations caused by the Gibbs-Wilbraham phenomenon in the spectral viscosity solution. Conservation is maintained by working with unphysical negative particle concentrations
Unstructured Spectral Element Model for Dispersive and Nonlinear Wave Propagation
DEFF Research Database (Denmark)
Engsig-Karup, Allan Peter; Eskilsson, Claes; Bigoni, Daniele
2016-01-01
We introduce a new stabilized high-order and unstructured numerical model for modeling fully nonlinear and dispersive water waves. The model is based on a nodal spectral element method of arbitrary order in space and a -transformed formulation due to Cai, Langtangen, Nielsen and Tveito (1998). In...
Models of Solar Irradiance Variations: Current Status Natalie A ...
Indian Academy of Sciences (India)
Abstract. 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 variations on time scales of minutes to hours are due to solar oscillations and granulation, variations on longer time scales are driven by the evolution of the ...
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.
CSIR Research Space (South Africa)
Kok, S
2010-10-01
Full Text Available Property changes occur in materials subjected to irradiation. The bulk of experimental data and associated empirical models are for isothermal irradiation. The form that these isothermal models take is usually closed form expressions in terms...
International Nuclear Information System (INIS)
Yang Xin; Zhao Xueheng; Hwang, H.-M.
2007-01-01
Riboflavin-sensitized phototransformation of 2,4,6-trinitrotoluene (TNT) under natural sunlight was investigated with reverse-phase high performance liquid chromatography/mass spectrometry (HPLC/MS) and gas chromatography/mass spectrometry (GC/MS). The effect of different spectral region of sunlight on TNT phototransformation in the absence or presence of riboflavin was also investigated by using optical filters with cut-off at 400 or 455 nm. The concentration of riboflavin in the phototransformation of TNT was optimized. Concentration of riboflavin and TNT was 1.0 and 50 μM, respectively. The rates of phototransformation of TNT under natural sunlight in the presence or absence of riboflavin were conformed to initial pseudo-first-order rate equation. The photolysis half life of TNT in the presence of riboflavin was 21.87 min, compared to 39 min in the absence of riboflavin under natural sunlight. Two major phototransformation products of TNT, 3,5-dinitroaniline (3,5-DNA) and 1,3,5-trinitrobenzene (1,3,5-TNB), were detected in the samples in the presence of riboflavin receiving irradiation at full wavelength or wavelength >400 nm. The results indicate that riboflavin mediates TNT sensitized-phototransfomation under natural sunlight or near-UV-vis light
Husna, Husyira Al; Shibata, Naoki; Sawano, Naoki; Ueno, Seiya; Ota, Yasuyuki; Minemoto, Takashi; Araki, Kenji; Nishioka, Kensuke
2013-09-01
Multi-junction solar cell is designed to have considerable effect towards the solar spectrum distribution so that the maximum solar radiation could be absorbed hence, enhancing the energy conversion efficiency of the cell. Due to its application in CPV system, the system's characteristics are more sensitive to environmental factor in comparison to flat-plate PV system which commonly equipped with Si-based solar cell. In this paper, the impact of environmental factors i.e. average photon energy (APE) and temperature of solar cell (Tcell) towards the performance of the tracking type CPV system were discussed. A year data period of direct spectral irradiance, cell temperature, and power output which recorded from November 2010 to October 2011 at a CPV system power generator plant located at Miyazaki, Japan was used in this study. The result showed that most frequent condition during operation was at APE = 1.87±0.005eV, Tcell = 65±2.5°C with performance ratio of 83.9%. Furthermore, an equivalent circuit simulation of a CPV subsystem in module unit was conducted in order to investigate the influence of environmental factors towards the performance of the module.
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 UV-A dose during this time period would be from 1.4 to 10.3 times more than the solar UV-A dose. Copyright © 2016 Elsevier B.V. All rights reserved.
Composite spectral functions for solving Volterra's population model
International Nuclear Information System (INIS)
Ramezani, M.; Razzaghi, M.; Dehghan, M.
2007-01-01
An approximate method for solving Volterra's population model for population growth of a species in a closed system is proposed. Volterra's model is a nonlinear integro-differential equation, where the integral term represents the effect of toxin. The approach is based upon composite spectral functions approximations. The properties of composite spectral functions consisting of few terms of orthogonal functions are presented and are utilized to reduce the solution of the Volterra's model to the solution of a system of algebraic equations. The method is easy to implement and yields very accurate result
On global and regional spectral evaluation of global geopotential models
International Nuclear Information System (INIS)
Ustun, A; Abbak, R A
2010-01-01
Spectral evaluation of global geopotential models (GGMs) is necessary to recognize the behaviour of gravity signal and its error recorded in spherical harmonic coefficients and associated standard deviations. Results put forward in this wise explain the whole contribution of gravity data in different kinds that represent various sections of the gravity spectrum. This method is more informative than accuracy assessment methods, which use external data such as GPS-levelling. Comparative spectral evaluation for more than one model can be performed both in global and local sense using many spectral tools. The number of GGMs has grown with the increasing number of data collected by the dedicated satellite gravity missions, CHAMP, GRACE and GOCE. This fact makes it necessary to measure the differences between models and to monitor the improvements in the gravity field recovery. In this paper, some of the satellite-only and combined models are examined in different scales, globally and regionally, in order to observe the advances in the modelling of GGMs and their strengths at various expansion degrees for geodetic and geophysical applications. The validation of the published errors of model coefficients is a part of this evaluation. All spectral tools explicitly reveal the superiority of the GRACE-based models when compared against the models that comprise the conventional satellite tracking data. The disagreement between models is large in local/regional areas if data sets are different, as seen from the example of the Turkish territory
Energy Technology Data Exchange (ETDEWEB)
Tahani, K.; Plume, R. [Department of Physics and Astronomy, University of Calgary, Calgary, AB T2N 1N4 (Canada); Bergin, E. A. [Department of Astronomy, University of Michigan, 500 Church Street, Ann Arbor, MI 48109 (United States); Tolls, V. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Phillips, T. G.; Lis, D. C. [California Institute of Technology, Cahill Center for Astronomy and Astrophysics 301-17, Pasadena, CA 91125 (United States); Caux, E. [Université de Toulouse, UPS-OMP, IRAP, F-31028 Toulouse (France); Cabrit, S.; Pagani, L. [LERMA, Observatoire de Paris, PSL Research University, CNRS, Sorbonne Universités, UPMC Univ. Paris 06, F-75014, Paris (France); Goicoechea, J. R. [Instituto de Ciencia de Materiales de Madrid (ICMM-CSIC). Sor Juana Ines de la Cruz 3, E-28049 Cantoblanco, Madrid (Spain); Goldsmith, P. F.; Pearson, J. C. [Jet Propulsion Laboratory, Caltech, Pasadena, CA 91109 (United States); Johnstone, D. [National Research Council Canada, Herzberg Institute of Astrophysics, 5071 West Saanich Road, Victoria, BC V9E 2E7 (Canada); Menten, K. M. [Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, D-53121 Bonn (Germany); Müller, H. S. P.; Ossenkopf-Okada, V. [I. Physikalisches Institut, Universität zu Köln, Zülpicher Strasse 77, D-50937 Köln (Germany); Tak, F. F. S. van der, E-mail: ktahani@ucalgary.ca [SRON Netherlands Institute for Space Research, P.O. Box 800, 9700 AV, Groningen (Netherlands)
2016-11-20
We present results from a comprehensive submillimeter spectral survey toward the source Orion South, based on data obtained with the Heterodyne Instrument for the Far-Infrared instrument on board the Herschel Space Observatory , covering the frequency range of 480 to 1900 GHz. We detect 685 spectral lines with signal-to-noise ratios (S/Ns) > 3 σ , originating from 52 different molecular and atomic species. We model each of the detected species assuming conditions of Local Thermodynamic Equilibrium. This analysis provides an estimate of the physical conditions of Orion South (column density, temperature, source size, and V {sub LSR}). We find evidence for three different cloud components: a cool ( T {sub ex} ∼ 20–40 K), spatially extended (>60″), and quiescent (Δ V {sub FWHM} ∼ 4 km s{sup -1}) component; a warmer ( T {sub ex} ∼ 80–100 K), less spatially extended (∼30″), and dynamic (Δ V {sub FWHM} ∼ 8 km s{sup -1}) component, which is likely affected by embedded outflows; and a kinematically distinct region ( T {sub ex} > 100 K; V {sub LSR} ∼ 8 km s{sup -1}), dominated by emission from species that trace ultraviolet irradiation, likely at the surface of the cloud. We find little evidence for the existence of a chemically distinct “hot-core” component, likely due to the small filling factor of the hot core or hot cores within the Herschel beam. We find that the chemical composition of the gas in the cooler, quiescent component of Orion South more closely resembles that of the quiescent ridge in Orion-KL. The gas in the warmer, dynamic component, however, more closely resembles that of the Compact Ridge and Plateau regions of Orion-KL, suggesting that higher temperatures and shocks also have an influence on the overall chemistry of Orion South.
A methodology for spectral wave model evaluation
Siqueira, S. A.; Edwards, K. L.; Rogers, W. E.
2017-12-01
Model evaluation is accomplished by comparing bulk parameters (e.g., significant wave height, energy period, and mean square slope (MSS)) calculated from the model energy spectra with those calculated from buoy energy spectra. Quality control of the observed data and choice of the frequency range from which the bulk parameters are calculated are critical steps in ensuring the validity of the model-data comparison. The compared frequency range of each observation and the analogous model output must be identical, and the optimal frequency range depends in part on the reliability of the observed spectra. National Data Buoy Center 3-m discus buoy spectra are unreliable above 0.3 Hz due to a non-optimal buoy response function correction. As such, the upper end of the spectrum should not be included when comparing a model to these data. Bioufouling of Waverider buoys must be detected, as it can harm the hydrodynamic response of the buoy at high frequencies, thereby rendering the upper part of the spectrum unsuitable for comparison. An important consideration is that the intentional exclusion of high frequency energy from a validation due to data quality concerns (above) can have major implications for validation exercises, especially for parameters such as the third and fourth moments of the spectrum (related to Stokes drift and MSS, respectively); final conclusions can be strongly altered. We demonstrate this by comparing outcomes with and without the exclusion, in a case where a Waverider buoy is believed to be free of biofouling. Determination of the appropriate frequency range is not limited to the observed spectra. Model evaluation involves considering whether all relevant frequencies are included. Guidance to make this decision is based on analysis of observed spectra. Two model frequency lower limits were considered. Energy in the observed spectrum below the model lower limit was calculated for each. For locations where long swell is a component of the wave
Stochastic Spectral Descent for Discrete Graphical Models
International Nuclear Information System (INIS)
Carlson, David; Hsieh, Ya-Ping; Collins, Edo; Carin, Lawrence; Cevher, Volkan
2015-01-01
Interest in deep probabilistic graphical models has in-creased in recent years, due to their state-of-the-art performance on many machine learning applications. Such models are typically trained with the stochastic gradient method, which can take a significant number of iterations to converge. Since the computational cost of gradient estimation is prohibitive even for modestly sized models, training becomes slow and practically usable models are kept small. In this paper we propose a new, largely tuning-free algorithm to address this problem. Our approach derives novel majorization bounds based on the Schatten- norm. Intriguingly, the minimizers of these bounds can be interpreted as gradient methods in a non-Euclidean space. We thus propose using a stochastic gradient method in non-Euclidean space. We both provide simple conditions under which our algorithm is guaranteed to converge, and demonstrate empirically that our algorithm leads to dramatically faster training and improved predictive ability compared to stochastic gradient descent for both directed and undirected graphical models.
Jåstad, Eirik O; Torheim, Turid; Villeneuve, Kathleen M; Kvaal, Knut; Hole, Eli O; Sagstuen, Einar; Malinen, Eirik; Futsaether, Cecilia M
2017-09-28
The amino acid l-α-alanine is the most commonly used material for solid-state electron paramagnetic resonance (EPR) dosimetry, due to the formation of highly stable radicals upon irradiation, with yields proportional to the radiation dose. Two major alanine radical components designated R1 and R2 have previously been uniquely characterized from EPR and electron-nuclear double resonance (ENDOR) studies as well as from quantum chemical calculations. There is also convincing experimental evidence of a third minor radical component R3, and a tentative radical structure has been suggested, even though no well-defined spectral signature has been observed experimentally. In the present study, temperature dependent EPR spectra of X-ray irradiated polycrystalline alanine were analyzed using five multivariate methods in further attempts to understand the composite nature of the alanine dosimeter EPR spectrum. Principal component analysis (PCA), maximum likelihood common factor analysis (MLCFA), independent component analysis (ICA), self-modeling mixture analysis (SMA), and multivariate curve resolution (MCR) were used to extract pure radical spectra and their fractional contributions from the experimental EPR spectra. All methods yielded spectral estimates resembling the established R1 spectrum. Furthermore, SMA and MCR consistently predicted both the established R2 spectrum and the shape of the R3 spectrum. The predicted shape of the R3 spectrum corresponded well with the proposed tentative spectrum derived from spectrum simulations. Thus, results from two independent multivariate data analysis techniques strongly support the previous evidence that three radicals are indeed present in irradiated alanine samples.
Modeling of microstructural evolution under irradiation
International Nuclear Information System (INIS)
Odette, G.R.
1979-01-01
Microstructural evolution under irradiation is an extremely complex phenomenon involving numerous interacting mechanisms which alter both the microstructure and microchemistry of structural alloys. Predictive procedures which correlate primary irradiation and material variables to microstructural response are needed to extrapolate from the imperfect data base, which will be available, to fusion reactor conditions. Clearly, a marriage between models and experiments is needed. Specific steps to achieving such a marriage in the form of composite correlation model analysis are outlined and some preliminary results presented. The strongly correlated nature of microstructural evolution is emphasized and it is suggested that rate theory models, resting on the principle of material balances and focusing on coupled point defect-microchemical segregation processes, may be a practical approach to correlation model development. (orig.)
Advanced Numerical Model for Irradiated Concrete
Energy Technology Data Exchange (ETDEWEB)
Giorla, Alain B. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
2015-03-01
In this report, we establish a numerical model for concrete exposed to irradiation to address these three critical points. The model accounts for creep in the cement paste and its coupling with damage, temperature and relative humidity. The shift in failure mode with the loading rate is also properly represented. The numerical model for creep has been validated and calibrated against different experiments in the literature [Wittmann, 1970, Le Roy, 1995]. Results from a simplified model are shown to showcase the ability of numerical homogenization to simulate irradiation effects in concrete. In future works, the complete model will be applied to the analysis of the irradiation experiments of Elleuch et al. [1972] and Kelly et al. [1969]. This requires a careful examination of the experimental environmental conditions as in both cases certain critical information are missing, including the relative humidity history. A sensitivity analysis will be conducted to provide lower and upper bounds of the concrete expansion under irradiation, and check if the scatter in the simulated results matches the one found in experiments. The numerical and experimental results will be compared in terms of expansion and loss of mechanical stiffness and strength. Both effects should be captured accordingly by the model to validate it. Once the model has been validated on these two experiments, it can be applied to simulate concrete from nuclear power plants. To do so, the materials used in these concrete must be as well characterized as possible. The main parameters required are the mechanical properties of each constituent in the concrete (aggregates, cement paste), namely the elastic modulus, the creep properties, the tensile and compressive strength, the thermal expansion coefficient, and the drying shrinkage. These can be either measured experimentally, estimated from the initial composition in the case of cement paste, or back-calculated from mechanical tests on concrete. If some
SAFARI 2000 AERONET-derived Diffuse Spectral Irradiance for Eight Core Sites
National Aeronautics and Space Administration — This data set contains monthly mean values of diffuse irradiance fraction [f(Ediff), or ratio of diffuse-to-total irradiance] at ground level for a 30-degree solar...
Spectral model for clear sky atmospheric longwave radiation
Li, Mengying; Liao, Zhouyi; Coimbra, Carlos F. M.
2018-04-01
An efficient spectrally resolved radiative model is used to calculate surface downwelling longwave (DLW) radiation (0 ∼ 2500 cm-1) under clear sky (cloud free) conditions at the ground level. The wavenumber spectral resolution of the model is 0.01 cm-1 and the atmosphere is represented by 18 non-uniform plane-parallel layers with pressure in each layer determined on a pressure-based coordinate system. The model utilizes the most up-to-date (2016) HITRAN molecular spectral data for 7 atmospheric gases: H2O, CO2, O3, CH4, N2O, O2 and N2. The MT_CKD model is used to calculate water vapor and CO2 continuum absorption coefficients. Longwave absorption and scattering coefficients for aerosols are modeled using Mie theory. For the non-scattering atmosphere (aerosol free), the surface DLW agrees within 2.91% with mean values from the InterComparison of Radiation Codes in Climate Models (ICRCCM) program, with spectral deviations below 0.035 W cm m-2. For a scattering atmosphere with typical aerosol loading, the DLW calculated by the proposed model agrees within 3.08% relative error when compared to measured values at 7 climatologically diverse SURFRAD stations. This relative error is smaller than a calibrated parametric model regressed from data for those same 7 stations, and within the uncertainty (+/- 5 W m-2) of pyrgeometers commonly used for meteorological and climatological applications. The DLW increases by 1.86 ∼ 6.57 W m-2 when compared with aerosol-free conditions, and this increment decreases with increased water vapor content due to overlap with water vapor bands. As expected, the water vapor content at the layers closest to the surface contributes the most to the surface DLW, especially in the spectral region 0 ∼ 700 cm-1. Additional water vapor content (mostly from the lowest 1 km of the atmosphere) contributes to the spectral range of 400 ∼ 650 cm-1. Low altitude aerosols ( ∼ 3.46 km or less) contribute to the surface value of DLW mostly in the
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...
Single-particle spectral density of the Hubbard model
Mehlig, B.; Eskes, H.; Hayn, R.; Meinders, M.B.J.
1995-01-01
We calculate the single-particle spectral function for the Hubbard model within the framework of a projection technique equivalent to the two-pole approximation. We show that the two-pole approximation can be well understood as an average characterization of the upper and the lower Hubbard bands,
SINGLE-PARTICLE SPECTRAL DENSITY OF THE HUBBARD-MODEL
MEHLIG, B; ESKES, H; HAYN, R; MEINDERS, MBJ
1995-01-01
We calculate the single-particle spectral function for the Hubbard model within the framework of a projection technique equivalent to the two-pole approximation. We show that the two-pole approximation can be well understood as an average characterization of the upper and the lower Hubbard bands,
International Nuclear Information System (INIS)
Yoon, Howard W.; Gibson, Charles E.
2002-01-01
The temporal stability of the National Institute of Standards and Technology (NIST) spectral irradiance scale as measured with broadband filter radiometers calibrated for absolute spectral irradiance responsivity is described. The working standard free-electron laser (FEL) lamps and the check standard FEL lamps have been monitored with radiometers in the ultraviolet and the visible wavelength regions. The measurements made with these two radiometers reveal that the NIST spectral irradiance scale as compared with an absolute thermodynamic scale has not changed by more than 1.5% in the visible from 1993 to 1999. Similar measurements in the ultraviolet reveal that the corresponding change is less than 1.5% from 1995 to 1999. Furthermore, a check of the spectral irradiance scale by six different filter radiometers calibrated for absolute spectral irradiance responsivity based on the high-accuracy cryogenic radiometer shows that the agreement between the present scale and the detector-based scale is better than 1.3% throughout the visible to the near-infrared wavelength region. These results validate the assigned spectral irradiance of the widely disseminated NIST or NIST-traceable standard sources
Ion irradiation effects on lithium niobate etalons for tunable spectral filters
Garranzo, D.; Ibarmia, S.; Alvarez-Herrero, A.; Olivares, J.; Crespillo, M.; Díaz, M.
2017-11-01
Solar Orbiter is a mission dedicated to solar and heliospheric physics. It was selected as the first mediumclass mission of ESA's Cosmic Vision 2015-2025 Programme. Solar Orbiter will be used to examine how the Sun creates and controls the heliosphere, the vast bubble of charged particles blown by the solar wind into the interstellar medium. One of the scientific payload elements of Solar Orbiter is the Polarimetric and Helioseismic Imager (PHI). The PHI instrument consists of two telescopes, a High Resolution Telescope (HRT) that will image a fraction of the solar disk at a resolution reaching {150 km at perihelion, and a Full Disk Telescope (FDT) to image the full solar disk during all phases of the orbit. PHI is a diffraction limited, wavelength tunable, quasi-monochromatic, polarisation sensitive imager. These capabilities are needed to infer the magnetic field and line-of-sight (LOS) velocity of the region targeted by the spacecraft. For the spectral analysis, PHI will use an order-sorting filter to isolate a bandpass of the order of 100 mÅ . The FilterGraph (FG) contains an etalon in single pass configuration as tunable spectral filter located inside a temperature stabilized oven. This filter will be made by means of a z-cut LiNbO3 crystal (about 300 microns thick) and multilayer coatings including a conductive one in order to apply a high voltage (up to 5 kV) and induce the required electric field to tune the filter. Solar Orbiter observing mission around the Sun will expose the PHI instrument to extreme radiation conditions, mainly dominated by solar high-energy particles released during severe solar events (protons with energies typically ranging from few keV up to several GeV) and the continuous isotropic background flux of galactic cosmic rays (heavy ions, from Z=1 to Z=92). The main concerns are whether the cumulated radiation damage can degrade the functionality of the filter or, in the worst case, the impact of a single highly ionizing particle
Directory of Open Access Journals (Sweden)
W. Gurlit
2005-01-01
Full Text Available Within the framework of the ENVISAT/-SCIAMACHY satellite validation, solar irradiance spectra are absolutely measured at moderate resolution in the UV/visible spectral range (in the UV from 316.7-418 nm and the visible from 400-652 nm at a full width half maximum resolution of 0.55 nm and 1.48 nm, respectively from aboard the azimuth-controlled LPMA/DOAS balloon gondola at around 32 km balloon float altitude. After accounting for the atmospheric extinction due to Rayleigh scattering and gaseous absorption (O3 and NO2, the measured solar spectra are compared with previous observations. Our solar irradiance spectrum perfectly agrees within +0.03% with the re-calibrated Kurucz et al. (1984 solar spectrum (Fontenla et al., 1999, called MODTRAN 3.7 in the visible spectral range (415-650 nm, but it is +2.1% larger in the (370-415 nm wavelength interval, and -4% smaller in the UV-A spectral range (316.7-370 nm, when the Kurucz spectrum is convolved to the spectral resolution of our instrument. Similar comparisons of the SOLSPEC (Thuillier et al., 1997, 1998a, b and SORCE/SIM (Harder et al., 2000 solar spectra with MODTRAN 3.7 confirms our findings with the values being -0.5%, +2%, and -1.4% for SOLSPEC -0.33%, -0.47%, and -6.2% for SORCE/SIM, respectively. Comparison of the SCIAMACHY solar spectrum from channels 1 to 4 (- re-calibrated by the University of Bremen - with MODTRAN 3.7 indicates an agreement within -0.4% in the visible spectral range (415-585 nm, -1.6% within the 370-415 nm, and -5.7% within 325-370 nm wavelength interval, in agreement with the results of the other sensors. In agreement with findings of Skupin et al. (2002 our study emphasizes that the present ESA SCIAMACHY level 1 calibration is systematically +15% larger in the considered wavelength intervals when compared to all available other solar irradiance measurements.
Zuber, Ralf; Sperfeld, Peter; Riechelmann, Stefan; Nevas, Saulius; Sildoja, Meelis; Seckmeyer, Gunther
2018-04-01
A compact array spectroradiometer that enables precise and robust measurements of solar UV spectral direct irradiance is presented. We show that this instrument can retrieve total ozone column (TOC) accurately. The internal stray light, which is often the limiting factor for measurements in the UV spectral range and increases the uncertainty for TOC analysis, is physically reduced so that no other stray-light reduction methods, such as mathematical corrections, are necessary. The instrument has been extensively characterised at the Physikalisch-Technische Bundesanstalt (PTB) in Germany. During an international total ozone measurement intercomparison at the Izaña Atmospheric Observatory in Tenerife, the high-quality applicability of the instrument was verified with measurements of the direct solar irradiance and subsequent TOC evaluations based on the spectral data measured between 12 and 30 September 2016. The results showed deviations of the TOC of less than 1.5 % from most other instruments in most situations and not exceeding 3 % from established TOC measurement systems such as Dobson or Brewer.
Observer model optimization of a spectral mammography system
Fredenberg, Erik; Åslund, Magnus; Cederström, Björn; Lundqvist, Mats; Danielsson, Mats
2010-04-01
Spectral imaging is a method in medical x-ray imaging to extract information about the object constituents by the material-specific energy dependence of x-ray attenuation. Contrast-enhanced spectral imaging has been thoroughly investigated, but unenhanced imaging may be more useful because it comes as a bonus to the conventional non-energy-resolved absorption image at screening; there is no additional radiation dose and no need for contrast medium. We have used a previously developed theoretical framework and system model that include quantum and anatomical noise to characterize the performance of a photon-counting spectral mammography system with two energy bins for unenhanced imaging. The theoretical framework was validated with synthesized images. Optimal combination of the energy-resolved images for detecting large unenhanced tumors corresponded closely, but not exactly, to minimization of the anatomical noise, which is commonly referred to as energy subtraction. In that case, an ideal-observer detectability index could be improved close to 50% compared to absorption imaging. Optimization with respect to the signal-to-quantum-noise ratio, commonly referred to as energy weighting, deteriorated detectability. For small microcalcifications or tumors on uniform backgrounds, however, energy subtraction was suboptimal whereas energy weighting provided a minute improvement. The performance was largely independent of beam quality, detector energy resolution, and bin count fraction. It is clear that inclusion of anatomical noise and imaging task in spectral optimization may yield completely different results than an analysis based solely on quantum noise.
Irradiation effects on polymer-model compounds
International Nuclear Information System (INIS)
Seguchi, Tadao; Hayakawa, Naohiro; Tamura, Naoyuki; Katsumura, Yosuke; Hayashi, Nariyuki; Tabata, Yoneho
1991-01-01
Irradiation effects on n-paraffins and squalane, used as models of polymers, were investigated by product analysis. Four n-paraffins, C 20 H 42 , C 21 H 44 , C 23 H 48 and C 24 H 50 , and squalane (C 30 H 62 ) were γ-irradiated under vacuum in liquid, crystalline and glassy states. The evolved gases were analyzed by gas chromatography and changes in molecular weight were analyzed by liquid chromatography and mass spectroscopy. G-values for crosslinking of n-paraffins were 1.2 for crystalline states (at 25 0 C) and 1.7 for liquid states (at 55 0 C), and showed no difference between odd and even carbon numbers. The G-value of liquid squalane was 1.7; it was 1.3 for the glassy state at low temperature (-77 0 C). Double bonds were common in the crosslinked products, especially after liquid-phase irradiation. The probability of chain scission was estimated as being negligible, though a small number of chain-scission products (which were products of scission at chain-ends or side chains) were observed by gas analysis. (author)
A regular analogue of the Smilansky model: spectral properties
Czech Academy of Sciences Publication Activity Database
Barseghyan, Diana; Exner, Pavel
2017-01-01
Roč. 80, č. 2 (2017), s. 177-192 ISSN 0034-4877 R&D Projects: GA ČR GA17-01706S Institutional support: RVO:61389005 Keywords : discrete spectrum * eigenvalue estimates * Smilansky model * spectral transition Subject RIV: BE - Theoretical Physics OBOR OECD: Atomic, molecular and chemical physics (physics of atoms and molecules including collision, interaction with radiation, magnetic resonances, Mössbauer effect) Impact factor: 0.604, year: 2016
Schmidtke, G.; Jacobi, Ch.; Nikutowski, B.; Erhardt, Ch.
2014-11-01
After a historical survey of space related EUV measurements in Germany and the role of Karl Rawer in pursuing this work, we describe present developments in EUV spectroscopy and provide a brief outlook on future activities. The group of Karl Rawer has performed the first scientific space project in Western Europe on 19th October 1954. Then it was decided to include the field of solar EUV spectroscopy in ionospheric investigations. Starting in 1957 an intensified development of instrumentation was going on to explore solar EUV radiation, atmospheric airglow and auroral emissions until the institute had to stop space activities in the early nineteen-eighties. EUV spectroscopy was continued outside of the institute during eight years. This area of work was supported again by the institute developing the Auto-Calibrating Spectrometers (SolACES) for a mission on the International Space Station (ISS). After more than six years in space the instrument is still in operation. Meanwhile the work on the primary task also to validate EUV data available from other space missions has made good progress. The first results of validating those data and combine them into one set of EUV solar spectral irradiance are very promising. It will be recommended for using it by the science and application community. Moreover, a new low-cost type of an EUV spectrometer is presented for monitoring the solar EUV radiation. It shall be further developed for providing EUV-TEC data to be applied in ionospheric models replacing the Covington index F10.7. Applying these data for example in the GNSS signal evaluation a more accurate determination of GNSS receiver positions is expected for correcting the propagation delays of navigation signals traveling through the ionosphere from space to earth. - Latest results in the field of solar EUV spectroscopy are discussed, too.
Additive action model for mixed irradiation
International Nuclear Information System (INIS)
Lam, G.K.Y.
1984-01-01
Recent experimental results indicate that a mixture of high and low LET radiation may have some beneficial features (such as lower OER but with skin sparing) for clinical use, and interest has been renewed in the study of mixtures of high and low LET radiation. Several standard radiation inactivation models can readily accommodate interaction between two mixed radiations, however, this is usually handled by postulating extra free parameters, which can only be determined by fitting to experimental data. A model without any free parameter is proposed to explain the biological effect of mixed radiations, based on the following two assumptions: (a) The combined biological action due to two radiations is additive, assuming no repair has taken place during the interval between the two irradiations; and (b) The initial physical damage induced by radiation develops into final biological effect (e.g. cell killing) over a relatively long period (hours) after irradiation. This model has been shown to provide satisfactory fit to the experiment results of previous studies
Modeling daylight from solar irradiation in Malaysia
International Nuclear Information System (INIS)
Ahmed, A.Z.; Sayigh, A.A.K.; Surendran, P.N.; Othman, M.Y.
1999-01-01
The oil crises in the seventies, the environmental impact by the extensive use of energy in the nineties and the recent economic recession in Asia have led to the rediscovery of the use of daylight in energy-conscious design in buildings, the economic implication of the excessive use of artificial lighting in potential of daylight. No daylight data is currently available in Malaysia and therefore there is a need to model the daylight availability based on other climatic parameters measured at meteorological stations. A study has been carried out to produce daylight data from measured climatic parameters, specifically solar irradiation and could cover. The Model Year Climate (MYC) data for the location of Subang (3 deg. 7', N 101 deg. 33' E), model to estimate daily diffuse irradiation was produced the average values of global (KG) and diffuse (KD) luminous efficacious were calculated and found to be 112 lm/W and 120 lm/W respectively. The value of 104 lm/W for the beam luminous efficacy (KB) was selected. Using cloud data cover data as input parameters, the nebulosity index was calculated to determine the sky condition in Subang, Malaysia, which was then classified as average or intermediate sky type, the hourly illuminance on horizontal and inclined surfaces at locations with similar sky conditions in Malaysia were then produced. (author)
EXPLORING DATA-DRIVEN SPECTRAL MODELS FOR APOGEE M DWARFS
Lua Birky, Jessica; Hogg, David; Burgasser, Adam J.; Jessica Birky
2018-01-01
The Cannon (Ness et al. 2015; Casey et al. 2016) is a flexible, data-driven spectral modeling and parameter inference framework, demonstrated on high-resolution Apache Point Galactic Evolution Experiment (APOGEE; λ/Δλ~22,500, 1.5-1.7µm) spectra of giant stars to estimate stellar labels (Teff, logg, [Fe/H], and chemical abundances) to precisions higher than the model-grid pipeline. The lack of reliable stellar parameters reported by the APOGEE pipeline for temperatures less than ~3550K, motivates extension of this approach to M dwarf stars. Using a training set of 51 M dwarfs with spectral types ranging M0-M9 obtained from SDSS optical spectra, we demonstrate that the Cannon can infer spectral types to a precision of +/-0.6 types, making it an effective tool for classifying high-resolution near-infrared spectra. We discuss the potential for extending this work to determine the physical stellar labels Teff, logg, and [Fe/H].This work is supported by the SDSS Faculty and Student (FAST) initiative.
Modelling irradiation effects in fusion materials
International Nuclear Information System (INIS)
Victoria, M.; Dudarev, S.; Boutard, J.L.; Diegele, E.; Laesser, R.; Almazouzi, A.; Caturla, M.J.; Fu, C.C.; Kaellne, J.; Malerba, L.; Nordlund, K.; Perlado, M.; Rieth, M.; Samaras, M.; Schaeublin, R.; Singh, B.N.; Willaime, F.
2007-01-01
We review the current status of the European fusion materials modelling programme. We describe recent findings and outline potential areas for future development. Large-scale density functional theory (DFT) calculations reveal the structure of the point defects in α-Fe, and highlight the crucial part played by magnetism. The calculations give accurate migration energies of point defects and the strength of their interaction with He atoms. Kinetic models based on DFT results reproduce the stages of radiation damage recovery in iron, and stages of He-desorption from pre-implanted iron. Experiments aimed at validating the models will be carried out in the future using a multi-beam ion irradiation facility chosen for its versatility and rapid feedback
Modelling irradiation effects in fusion materials
Energy Technology Data Exchange (ETDEWEB)
Victoria, M. [Instituto de Fusion Nuclear, Universidad Politecnica de Madrid, c/Jose Gutierrez Abascal 2, 28006 Madrid (Spain); Dudarev, S. [EURATOM/UKAEA Fusion Association, Culham Science Centre, Oxfordshire OX14 3DB, UK and Department of Physics, Imperial College, Exhibition Road, London SW7 2AZ (United Kingdom); Boutard, J.L. [EFDA-CSU Garching, Boltzmannstrasse 2, D-85748 Garching (Germany)], E-mail: jean-louis.boutard@tech.efda.org; Diegele, E.; Laesser, R. [EFDA-CSU Garching, Boltzmannstrasse 2, D-85748 Garching (Germany); Almazouzi, A. [Structural Materials Expert Group, Nuclear Materials Science Institute, SCK-CEN, Boeretang 200, B-2400 Mol (Belgium); Caturla, M.J. [Departamento de Fisica Aplicada, Universidad de Alicante, 03690 San Vicente de Raspeig (Spain); Fu, C.C. [Service de Metallurgie Physique, CEA/Saclay, F-91191 Gif sur Yvette Cedex (France); Kaellne, J. [Department of Engineering Sciences, Uppsala University, Box 534, S-751 21 Uppsala (Sweden); Malerba, L. [Structural Materials Expert Group, Nuclear Materials Science Institute, SCK-CEN, Boeretang 200, B-2400 Mol (Belgium); Nordlund, K. [Association EURATOM-Tekes, Accelerator Laboratory, P.O. Box 43, 00014 University of Helsinki (Finland); Perlado, M. [Instituto de Fusion Nuclear, Universidad Politecnica de Madrid, c/Jose Gutierrez Abascal 2, 28006 Madrid (Spain); Rieth, M. [Forschungszentrum Karlsruhe, Institut fuer Materialforschung I, P.O. Box 3640, D-76021 Karlsruhe (Germany); Samaras, M. [Paul Scherrer Institute, Nuclear Energy and Safety Department, CH-5232 Villigen PSI (Switzerland); Schaeublin, R. [Ecole Polytechnique Federale de Lausanne (EPFL), Centre de Recherches en Physique des Plasmas, Association Euratom-Confederation Suisse, CH-5232 Villigen PSI (Switzerland); Singh, B.N. [Department of Materials Research, Risoe National Laboratory, DK-4000 Roskilde (Denmark); Willaime, F. [Service de Metallurgie Physique, CEA/Saclay, F-91191 Gif sur Yvette Cedex (France)
2007-10-15
We review the current status of the European fusion materials modelling programme. We describe recent findings and outline potential areas for future development. Large-scale density functional theory (DFT) calculations reveal the structure of the point defects in {alpha}-Fe, and highlight the crucial part played by magnetism. The calculations give accurate migration energies of point defects and the strength of their interaction with He atoms. Kinetic models based on DFT results reproduce the stages of radiation damage recovery in iron, and stages of He-desorption from pre-implanted iron. Experiments aimed at validating the models will be carried out in the future using a multi-beam ion irradiation facility chosen for its versatility and rapid feedback.
Spectral flow as a map between N = (2 , 0)-models
Athanasopoulos, P.; Faraggi, A. E.; Gepner, D.
2014-07-01
The space of (2 , 0) models is of particular interest among all heterotic-string models because it includes the models with the minimal SO (10) unification structure, which is well motivated by the Standard Model of particle physics data. The fermionic Z2 ×Z2 heterotic-string models revealed the existence of a new symmetry in the space of string configurations under the exchange of spinors and vectors of the SO (10) GUT group, dubbed spinor-vector duality. In this paper we generalize this idea to arbitrary internal rational conformal field theories (RCFTs). We explain how the spectral flow operator normally acting within a general (2 , 2) theory can be used as a map between (2 , 0) models. We describe the details, give an example and propose more simple currents that can be used in a similar way.
Fermentation process tracking through enhanced spectral calibration modeling.
Triadaphillou, Sophia; Martin, Elaine; Montague, Gary; Norden, Alison; Jeffkins, Paul; Stimpson, Sarah
2007-06-15
The FDA process analytical technology (PAT) initiative will materialize in a significant increase in the number of installations of spectroscopic instrumentation. However, to attain the greatest benefit from the data generated, there is a need for calibration procedures that extract the maximum information content. For example, in fermentation processes, the interpretation of the resulting spectra is challenging as a consequence of the large number of wavelengths recorded, the underlying correlation structure that is evident between the wavelengths and the impact of the measurement environment. Approaches to the development of calibration models have been based on the application of partial least squares (PLS) either to the full spectral signature or to a subset of wavelengths. This paper presents a new approach to calibration modeling that combines a wavelength selection procedure, spectral window selection (SWS), where windows of wavelengths are automatically selected which are subsequently used as the basis of the calibration model. However, due to the non-uniqueness of the windows selected when the algorithm is executed repeatedly, multiple models are constructed and these are then combined using stacking thereby increasing the robustness of the final calibration model. The methodology is applied to data generated during the monitoring of broth concentrations in an industrial fermentation process from on-line near-infrared (NIR) and mid-infrared (MIR) spectrometers. It is shown that the proposed calibration modeling procedure outperforms traditional calibration procedures, as well as enabling the identification of the critical regions of the spectra with regard to the fermentation process.
A Practical Irradiance Model for Bifacial PV Modules: Preprint
Energy Technology Data Exchange (ETDEWEB)
Marion, Bill; MacAlpine, Sara; Deline, Chris; Asgharzadeh, Amir; Toor, Fatima; Riley, Daniel; Stein, Joshua; Hansen, Clifford
2017-06-15
A model, suitable for a row or multiple rows of photovoltaic (PV) modules, is presented for estimating the backside irradiance for bifacial PV modules. The model, which includes the effects of shading by the PV rows, is based on the use of configuration factors (CFs) to determine the fraction of a source of irradiance that is received by the backside of the PV module. Backside irradiances are modeled along the sloped height of the PV module, but assumed not to vary along the length of the PV row. The backside irradiances are corrected for angle-of-incidence losses and may be added to the front side irradiance to determine the total irradiance resource for the PV cell. Model results are compared with the measured backside irradiances for NREL and Sandia PV systems, and with results when using the RADIANCE ray tracing program.
A Practical Irradiance Model for Bifacial PV Modules
Energy Technology Data Exchange (ETDEWEB)
Marion, Bill; MacAlpine, Sara; Deline, Chris; Asgharzadeh, Amir; Toor, Fatima; Riley, Daniel; Stein, Joshua; Hansen, Clifford
2017-06-21
A model, suitable for a row or multiple rows of photovoltaic (PV) modules, is presented for estimating the backside irradiance for bifacial PV modules. The model, which includes the effects of shading by the PV rows, is based on the use of configuration factors to determine the fraction of a source of irradiance that is received by the backside of the PV module. Backside irradiances are modeled along the sloped height of the PV module, but assumed not to vary along the length of the PV row. The backside irradiances are corrected for angle-of-incidence losses and may be added to the front side irradiance to determine the total irradiance resource for the PV cell. Model results are compared with the measured backside irradiances for NREL and Sandia PV systems, and with results when using ray tracing software.
Mathematical Model for Post-Irradiation Haemopoiesis
Energy Technology Data Exchange (ETDEWEB)
Okunewick, J. P.; Kretchmar, A. L. [Rand Corporation, Santa Monica, CA (United States); Medical Division, Oak Ridge Associated Universities, Oak Ridge, TN (United States)
1968-08-15
A model for haemopoiesis has been constructed based on the following hypothesis: (a) Haemopoietic stem cells have the capability of either reproducing as stem cells or differentiating into specialized blood cells of at least two different types; (b) The size of the stem-cell compartment is in part regulated by the rate of increase due to stem-cell reproduction and in part by the rate of loss of stem cells through differentiation; (c) In addition, the size of the stem-cell compartment is in part regulated by a competitive cell-to-cell interaction between the stem-cells themselves and between the differentiating cells and the stem-cells, such that the presence of an exceptionally large number of either cell type would have a repressive effect on the rate of increase of the stem-cell population. This model has been applied to the post-irradiation erythropoietic behaviour of the rat. In the computer studies with the model, an X-ray dose sufficient to inhibit reproduction in 50% of the erythroid stem cells was assumed. It was also assumed that reproduction and differentiation are genetically separately controlled processes and that, therefore, some part of the reproductively injured cells were still capable of differentiation. Under these conditions the model predicted an abortive rise in reticulocyte number, peaking at about 6 days. True recovery was predicted to occur at about 16 days. Both the abortive rise and the true recovery were also present in those segments of the model representing earlier erythroid cells, occurring at progressively earlier times in progressively more primitive cells. Comparison of the model's predictions with experimentally obtained data for post-irradiation erythroid recovery showed a good agreement both with respect to the time of the abortive peak and the time of true recovery. (author)
Mathematical Model for Post-Irradiation Haemopoiesis
International Nuclear Information System (INIS)
Okunewick, J.P.; Kretchmar, A.L.
1968-01-01
A model for haemopoiesis has been constructed based on the following hypothesis: (a) Haemopoietic stem cells have the capability of either reproducing as stem cells or differentiating into specialized blood cells of at least two different types; (b) The size of the stem-cell compartment is in part regulated by the rate of increase due to stem-cell reproduction and in part by the rate of loss of stem cells through differentiation; (c) In addition, the size of the stem-cell compartment is in part regulated by a competitive cell-to-cell interaction between the stem-cells themselves and between the differentiating cells and the stem-cells, such that the presence of an exceptionally large number of either cell type would have a repressive effect on the rate of increase of the stem-cell population. This model has been applied to the post-irradiation erythropoietic behaviour of the rat. In the computer studies with the model, an X-ray dose sufficient to inhibit reproduction in 50% of the erythroid stem cells was assumed. It was also assumed that reproduction and differentiation are genetically separately controlled processes and that, therefore, some part of the reproductively injured cells were still capable of differentiation. Under these conditions the model predicted an abortive rise in reticulocyte number, peaking at about 6 days. True recovery was predicted to occur at about 16 days. Both the abortive rise and the true recovery were also present in those segments of the model representing earlier erythroid cells, occurring at progressively earlier times in progressively more primitive cells. Comparison of the model's predictions with experimentally obtained data for post-irradiation erythroid recovery showed a good agreement both with respect to the time of the abortive peak and the time of true recovery. (author)
International Nuclear Information System (INIS)
Cucu, Delia-Irina; Dorobantu, Ioan
2002-01-01
Beta-carotene is part of the class of the carotenoid pigments that have a special function in the pigmentation of flowers and fruits. These pigments are essential in photosynthesis where they are retaining energy and are photoprotectors by forming the redox system. They are also precursors of vitamin A, pigments involved in the process of seeing. Beta-carotene is responsible for the growth and development of organisms, for the protection and recovery of epithelial tissue, etc. Next to chlorophyll, carotenoids are the major components of the complex pigment-protein from the thylacoide membrane, and some of them, such as beta-carotene, were for a long time considered to be protecting the membrane against destructive events caused by the over excitement of the chlorophyll. This paper presents spectral difference method for physico-chemical characterisation of three components (beta-carotene, chlorophyll a and b) from Calendula officinalis leaves and stalks, after irradiation of germinated seeds. The germinated seeds of Calendula officinalis has been irradiated at 8 different doses ( 1 k Rad, 3 k Rad, 5 k Rad, 10 k Rad, 20 k Rad, 50 k Rad, 100 k Rad, 500 krad), one set of seeds remaining unirradiated for comparison. The plants had been grown in the same conditions of light, temperature and humidity. The identification of beta-carotene was performed through thin layer chromatography. The chemical concentrations of beta-carotene, chlorophyll a and b were determined by spectral difference method. (authors)
Nonlinear spectral mixing theory to model multispectral signatures
Energy Technology Data Exchange (ETDEWEB)
Borel, C.C. [Los Alamos National Lab., NM (United States). Astrophysics and Radiation Measurements Group
1996-02-01
Nonlinear spectral mixing occurs due to multiple reflections and transmissions between discrete surfaces, e.g. leaves or facets of a rough surface. The radiosity method is an energy conserving computational method used in thermal engineering and it models nonlinear spectral mixing realistically and accurately. In contrast to the radiative transfer method the radiosity method takes into account the discreteness of the scattering surfaces (e.g. exact location, orientation and shape) such as leaves and includes mutual shading between them. An analytic radiosity-based scattering model for vegetation was developed and used to compute vegetation indices for various configurations. The leaf reflectance and transmittance was modeled using the PROSPECT model for various amounts of water, chlorophyll and variable leaf structure. The soil background was modeled using SOILSPEC with a linear mixture of reflectances of sand, clay and peat. A neural network and a geometry based retrieval scheme were used to retrieve leaf area index and chlorophyll concentration for dense canopies. Only simulated canopy reflectances in the 6 visible through short wave IR Landsat TM channels were used. The authors used an empirical function to compute the signal-to-noise ratio of a retrieved quantity.
VNIR spectral modeling of Mars analogue rocks: first results
Pompilio, L.; Roush, T.; Pedrazzi, G.; Sgavetti, M.
Knowledge regarding the surface composition of Mars and other bodies of the inner solar system is fundamental to understanding of their origin, evolution, and internal structures. Technological improvements of remote sensors and associated implications for planetary studies have encouraged increased laboratory and field spectroscopy research to model the spectral behavior of terrestrial analogues for planetary surfaces. This approach has proven useful during Martian surface and orbital missions, and petrologic studies of Martian SNC meteorites. Thermal emission data were used to suggest two lithologies occurring on Mars surface: basalt with abundant plagioclase and clinopyroxene and andesite, dominated by plagioclase and volcanic glass [1,2]. Weathered basalt has been suggested as an alternative to the andesite interpretation [3,4]. Orbital VNIR spectral imaging data also suggest the crust is dominantly basaltic, chiefly feldspar and pyroxene [5,6]. A few outcrops of ancient crust have higher concentrations of olivine and low-Ca pyroxene, and have been interpreted as cumulates [6]. Based upon these orbital observations future lander/rover missions can be expected to encounter particulate soils, rocks, and rock outcrops. Approaches to qualitative and quantitative analysis of remotely-acquired spectra have been successfully used to infer the presence and abundance of minerals and to discover compositionally associated spectral trends [7-9]. Both empirical [10] and mathematical [e.g. 11-13] methods have been applied, typically with full compositional knowledge, to chiefly particulate samples and as a result cannot be considered as objective techniques for predicting the compositional information, especially for understanding the spectral behavior of rocks. Extending the compositional modeling efforts to include more rocks and developing objective criteria in the modeling are the next required steps. This is the focus of the present investigation. We present results of
DEFF Research Database (Denmark)
LASSEN, C.; PLOUG, H.; JØRGENSEN, BB
1992-01-01
(bacteriochlorophyll a). Infrared scalar irradiance reached 200% of incident light intensity at 0.0-0.3-mm depth and IR penetration was independent of the development of a cyanobacterial surface film. At high incident light intensity, 740 muEinst m-2 s-1, the photosynthetic efficiency at 1.0-mm depth was 10-fold...... higher than in the uppermost 0.0-0.6 mm of the sediment. The lower boundary of the euphotic zone (detectable gross photosynthesis) was at a mean light level of greater-than-or-equal-to 7.5 muEinst m-2 s-1.......Scalar irradiance and oxygenic photosynthesis were measured simultaneously at 100-mum spatial resolution by a fiber-optic scalar irradiance microsensor and an oxygen microelectrode spaced 120 mum apart. Marine microbial mats on sandy sediments along the coast of Limfjorden, Denmark, were dominated...
K-correlation power spectral density and surface scatter model
Dittman, Michael G.
2006-08-01
The K-Correlation or ABC model for surface power spectral density (PSD) and BRDF has been around for years. Eugene Church and John Stover, in particular, have published descriptions of its use in describing smooth surfaces. The model has, however, remained underused in the optical analysis community partially due to the lack of a clear summary tailored toward that application. This paper provides the K-Correlation PSD normalized to σ(λ) and BRDF normalized to TIS(σ,λ) in a format intended to be used by stray light analysts. It is hoped that this paper will promote use of the model by analysts and its incorporation as a standard tool into stray light modeling software.
Analyzing availability using transfer function models and cross spectral analysis
International Nuclear Information System (INIS)
Singpurwalla, N.D.
1980-01-01
The paper shows how the methods of multivariate time series analysis can be used in a novel way to investigate the interrelationships between a series of operating (running) times and a series of maintenance (down) times of a complex system. Specifically, the techniques of cross spectral analysis are used to help obtain a Box-Jenkins type transfer function model for the running times and the down times of a nuclear reactor. A knowledge of the interrelationships between the running times and the down times is useful for an evaluation of maintenance policies, for replacement policy decisions, and for evaluating the availability and the readiness of complex systems
Analysis of errors in spectral reconstruction with a Laplace transform pair model
International Nuclear Information System (INIS)
Archer, B.R.; Bushong, S.C.
1985-01-01
The sensitivity of a Laplace transform pair model for spectral reconstruction to random errors in attenuation measurements of diagnostic x-ray units has been investigated. No spectral deformation or significant alteration resulted from the simulated attenuation errors. It is concluded that the range of spectral uncertainties to be expected from the application of this model is acceptable for most scientific applications. (author)
A Spectral Evaluation of Models Performances in Mediterranean Oak Woodlands
Vargas, R.; Baldocchi, D. D.; Abramowitz, G.; Carrara, A.; Correia, A.; Kobayashi, H.; Papale, D.; Pearson, D.; Pereira, J.; Piao, S.; Rambal, S.; Sonnentag, O.
2009-12-01
Ecosystem processes are influenced by climatic trends at multiple temporal scales including diel patterns and other mid-term climatic modes, such as interannual and seasonal variability. Because interactions between biophysical components of ecosystem processes are complex, it is important to test how models perform in frequency (e.g. hours, days, weeks, months, years) and time (i.e. day of the year) domains in addition to traditional tests of annual or monthly sums. Here we present a spectral evaluation using wavelet time series analysis of model performance in seven Mediterranean Oak Woodlands that encompass three deciduous and four evergreen sites. We tested the performance of five models (CABLE, ORCHIDEE, BEPS, Biome-BGC, and JULES) on measured variables of gross primary production (GPP) and evapotranspiration (ET). In general, model performance fails at intermediate periods (e.g. weeks to months) likely because these models do not represent the water pulse dynamics that influence GPP and ET at these Mediterranean systems. To improve the performance of a model it is critical to identify first where and when the model fails. Only by identifying where a model fails we can improve the model performance and use them as prognostic tools and to generate further hypotheses that can be tested by new experiments and measurements.
Simulation model for electron irradiated IGZO thin film transistors
Dayananda, G. K.; Shantharama Rai, C.; Jayarama, A.; Kim, Hyun Jae
2018-02-01
An efficient drain current simulation model for the electron irradiation effect on the electrical parameters of amorphous In-Ga-Zn-O (IGZO) thin-film transistors is developed. The model is developed based on the specifications such as gate capacitance, channel length, channel width, flat band voltage etc. Electrical parameters of un-irradiated IGZO samples were simulated and compared with the experimental parameters and 1 kGy electron irradiated parameters. The effect of electron irradiation on the IGZO sample was analysed by developing a mathematical model.
Spectral action for Bianchi type-IX cosmological models
International Nuclear Information System (INIS)
Fan, Wentao; Fathizadeh, Farzad; Marcolli, Matilde
2015-01-01
A rationality result previously proved for Robertson-Walker metrics is extended to a homogeneous anisotropic cosmological model, namely the Bianchi type-IX minisuperspace. It is shown that the Seeley-de Witt coefficients appearing in the expansion of the spectral action for the Bianchi type-IX geometry are expressed in terms of polynomials with rational coefficients in the cosmic evolution factors w_1(t),w_2(t),w_3(t), and their higher derivates with respect to time. We begin with the computation of the Dirac operator of this geometry and calculate the coefficients a_0,a_2,a_4 of the spectral action by using heat kernel methods and parametric pseudodifferential calculus. An efficient method is devised for computing the Seeley-de Witt coefficients of a geometry by making use of Wodzicki’s noncommutative residue, and it is confirmed that the method checks out for the cosmological model studied in this article. The advantages of the new method are discussed, which combined with symmetries of the Bianchi type-IX metric, yield an elegant proof of the rationality result.
Spectral action for Bianchi type-IX cosmological models
Energy Technology Data Exchange (ETDEWEB)
Fan, Wentao; Fathizadeh, Farzad; Marcolli, Matilde [Division of Physics, Mathematics and Astronomy, California Institute of Technology,1200 E. California Blvd., Pasadena, CA 91125 (United States)
2015-10-13
A rationality result previously proved for Robertson-Walker metrics is extended to a homogeneous anisotropic cosmological model, namely the Bianchi type-IX minisuperspace. It is shown that the Seeley-de Witt coefficients appearing in the expansion of the spectral action for the Bianchi type-IX geometry are expressed in terms of polynomials with rational coefficients in the cosmic evolution factors w{sub 1}(t),w{sub 2}(t),w{sub 3}(t), and their higher derivates with respect to time. We begin with the computation of the Dirac operator of this geometry and calculate the coefficients a{sub 0},a{sub 2},a{sub 4} of the spectral action by using heat kernel methods and parametric pseudodifferential calculus. An efficient method is devised for computing the Seeley-de Witt coefficients of a geometry by making use of Wodzicki’s noncommutative residue, and it is confirmed that the method checks out for the cosmological model studied in this article. The advantages of the new method are discussed, which combined with symmetries of the Bianchi type-IX metric, yield an elegant proof of the rationality result.
Preliminary report on NTS spectral gamma logging and calibration models
International Nuclear Information System (INIS)
Mathews, M.A.; Warren, R.G.; Garcia, S.R.; Lavelle, M.J.
1985-01-01
Facilities are now available at the Nevada Test Site (NTS) in Building 2201 to calibrate spectral gamma logging equipment in environments of low radioactivity. Such environments are routinely encountered during logging of holes at the NTS. Four calibration models were delivered to Building 2201 in January 1985. Each model, or test pit, consists of a stone block with a 12-inch diameter cored borehole. Preliminary radioelement values from the core for the test pits range from 0.58 to 3.83% potassium (K), 0.48 to 29.11 ppm thorium (Th), and 0.62 to 40.42 ppm uranium (U). Two satellite holes, U19ab number2 and U19ab number3, were logged during the winter of 1984-1985. The response of these logs correlates with contents of the naturally radioactive elements K. Th. and U determined in samples from petrologic zones that occur within these holes. Based on these comparisons, the spectral gamma log aids in the recognition and mapping of subsurface stratigraphic units and alteration features associated with unusual concentration of these radioactive elements, such as clay-rich zones
Toward an Empirically-based Parametric Explosion Spectral Model
Ford, S. R.; Walter, W. R.; Ruppert, S.; Matzel, E.; Hauk, T. F.; Gok, R.
2010-12-01
Small underground nuclear explosions need to be confidently detected, identified, and characterized in regions of the world where they have never occurred. We develop a parametric model of the nuclear explosion seismic source spectrum derived from regional phases (Pn, Pg, and Lg) that is compatible with earthquake-based geometrical spreading and attenuation. Earthquake spectra are fit with a generalized version of the Brune spectrum, which is a three-parameter model that describes the long-period level, corner-frequency, and spectral slope at high-frequencies. These parameters are then correlated with near-source geology and containment conditions. There is a correlation of high gas-porosity (low strength) with increased spectral slope. However, there are trade-offs between the slope and corner-frequency, which we try to independently constrain using Mueller-Murphy relations and coda-ratio techniques. The relationship between the parametric equation and the geologic and containment conditions will assist in our physical understanding of the nuclear explosion source, and aid in the prediction of observed local and regional distance seismic amplitudes for event identification and yield determination in regions with incomplete or no prior history of underground nuclear testing.
Spectral Irradiance Calibration in the Infrared. XIV: the Absolute Calibration of 2MASS
Cohen, Martin; Wheaton, Wm. A.; Megeath, S. T.
2003-01-01
Element-by-element we have combined the optical components in the three 2MASS cameras, and incorporated detector quantum efficiency curves and site-specific atmospheric transmissions, to create three relative spectral response curves (RSRs). We provide absolute 2MASS attributes associated with "zero magnitude" in the JHKs bands so that these RSRs may be used for synthetic photometry. The RSRs tie 2MASS to the Cohen-Walker-Witteborn framework of absolute photometry and spectra for the purpose ...
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)
Marchisio, Andrea; Minella, Marco; Maurino, Valter; Minero, Claudio; Vione, Davide
2015-04-15
Chromophoric dissolved organic matter (CDOM) in surface waters is a photochemical source of several transient species such as CDOM triplet states ((3)CDOM*), singlet oxygen ((1)O2) and the hydroxyl radical (OH). By irradiation of lake water samples, it is shown here that the quantum yields for the formation of these transients by CDOM vary depending on the irradiation wavelength range, in the order UVB > UVA > blue. A possible explanation is that radiation at longer wavelengths is preferentially absorbed by the larger CDOM fractions, which show lesser photoactivity compared to smaller CDOM moieties. The quantum yield variations in different spectral ranges were definitely more marked for (3)CDOM* and OH compared to (1)O2. The decrease of the quantum yields with increasing wavelength has important implications for the photochemistry of surface waters, because long-wavelength radiation penetrates deeper in water columns compared to short-wavelength radiation. The average steady-state concentrations of the transients ((3)CDOM*, (1)O2 and OH) were modelled in water columns of different depths, based on the experimentally determined wavelength trends of the formation quantum yields. Important differences were found between such modelling results and those obtained in a wavelength-independent quantum yield scenario. Copyright © 2015 Elsevier Ltd. All rights reserved.
International Nuclear Information System (INIS)
Schneider, W.; Kuepper, H.; Pott, G.; Borchardt, G.; Segelhorst, G.; Thoene, L.; Weise, L.
1986-10-01
For the German project 'Forschungsvorhaben Komponentensicherheit' (FKS, i.e., Structural Integrity of Components) steel specimen irradiations have been carried out in the Juelich Merlin-type reactor (FRJ-1). The neutron monitoring to these irradiations is described in a German report (Juel-2087). In this context, some special considerations and results are given here, i.e., an experimental investigation of the fast neutron spectrum variation over a thick steel plate (in a special dosimetry test experiment); a comparison of the outcome of this investigation with the results from other FKS participants; and finally, the evaluation of the neutron exposure expressed in displacements per atom (dpa) in the centre of that steel plate. (orig.)
Neutronic Modelling in Support of the Irradiation Programmes
International Nuclear Information System (INIS)
Koonen, E.
2005-01-01
Irradiation experiments are generally conducted to determine some specific characteristics of the concerned fuels and structural materials under well defined irradiation conditions. For the determination of the latter the BR2 division has an autonomous reactor physics cell and has implemented the required computational tools. The major tool used is a three-dimensional full-scale Monte Carlo model of the BR2 reactor developed under MCNP-4C for the simulation of irradiation conditions. The objectives of work performed by SCK-CEN are to evaluate and adjust irradiation conditions by adjustments of the environment, differential rod positions, axial and azimuthal positioning of the samples, global power level, ...; to deliver reliable, well defined irradiation condition and fluence data during and after irradiation; to assist the designer of new irradiation devices by simulations and neutronic optimisations of design options; to provide computational support to related projects as a way to valorise the capabilities that the BR2 reactor can offer
Hayden, W. L.; Robinson, L. H.
1972-01-01
Spectral analyses of angle-modulated communication systems is studied by: (1) performing a literature survey of candidate power spectrum computational techniques, determining the computational requirements, and formulating a mathematical model satisfying these requirements; (2) implementing the model on UNIVAC 1230 digital computer as the Spectral Analysis Program (SAP); and (3) developing the hardware specifications for a data acquisition system which will acquire an input modulating signal for SAP. The SAP computational technique uses extended fast Fourier transform and represents a generalized approach for simple and complex modulating signals.
Damé, Luc; Bolsée, David; Meftah, Mustapha; Irbah, Abdenour; Hauchecorne, Alain; Bekki, Slimane; Pereira, Nuno; Cessateur, Marchand; Gäel; , Marion; et al.
2016-10-01
Accurate measurements of Solar Spectral Irradiance (SSI) are of primary importance for a better understanding of solar physics and of the impact of solar variability on climate (via Earth's atmospheric photochemistry). The acquisition of a top of atmosphere reference solar spectrum and of its temporal and spectral variability during the unusual solar cycle 24 is of prime interest for these studies. These measurements are performed since April 2008 with the SOLSPEC spectro-radiometer from the far ultraviolet to the infrared (166 nm to 3088 nm). This instrument, developed under a fruitful LATMOS/BIRA-IASB collaboration, is part of the Solar Monitoring Observatory (SOLAR) payload, externally mounted on the Columbus module of the International Space Station (ISS). The SOLAR mission, with its actual 8 years duration, will cover almost the entire solar cycle 24. We present here the in-flight operations and performances of the SOLSPEC instrument, including the engineering corrections, calibrations and improved know-how procedure for aging corrections. Accordingly, a SSI reference spectrum from the UV to the NIR will be presented, together with its variability in the UV, as measured by SOLAR/SOLSPEC for 8 years. Uncertainties on these measurements and comparisons with other instruments will be briefly discussed.
Portable gamma-irradiator - a modified model
International Nuclear Information System (INIS)
Pandev, I.N.; Christova, M.G.; Stefanov, S.D.; Gentchev, N.V.; Bakardjiev, S.T.; Christov, C.D.; Genov, D.T.
1983-01-01
A new modification of a portable gamma-irradiator has been designed with a relatively large irradiation volume, good homogeneity of the gamma field, small overall dimension, light biological shielding, and simple mechanics. It is possible to irradiate materials in two cylindrical volumes (3 l and 6 l) with different dose rates. 137 Cs is used as a radiation source. Depending on application, the irradiator can be charged with various total activities up to 6.66 x 10 14 Bq (18 kCi). The dose rate can be also charged up to the maximum by different positions of the source element. The gamma-irradiator can be used for scientific studies and for industrial purposes. (author)
Martian Radiative Transfer Modeling Using the Optimal Spectral Sampling Method
Eluszkiewicz, J.; Cady-Pereira, K.; Uymin, G.; Moncet, J.-L.
2005-01-01
The large volume of existing and planned infrared observations of Mars have prompted the development of a new martian radiative transfer model that could be used in the retrievals of atmospheric and surface properties. The model is based on the Optimal Spectral Sampling (OSS) method [1]. The method is a fast and accurate monochromatic technique applicable to a wide range of remote sensing platforms (from microwave to UV) and was originally developed for the real-time processing of infrared and microwave data acquired by instruments aboard the satellites forming part of the next-generation global weather satellite system NPOESS (National Polarorbiting Operational Satellite System) [2]. As part of our on-going research related to the radiative properties of the martian polar caps, we have begun the development of a martian OSS model with the goal of using it to perform self-consistent atmospheric corrections necessary to retrieve caps emissivity from the Thermal Emission Spectrometer (TES) spectra. While the caps will provide the initial focus area for applying the new model, it is hoped that the model will be of interest to the wider Mars remote sensing community.
Sensitivity experiments to mountain representations in spectral models
Directory of Open Access Journals (Sweden)
U. Schlese
2000-06-01
Full Text Available This paper describes a set of sensitivity experiments to several formulations of orography. Three sets are considered: a "Standard" orography consisting of an envelope orography produced originally for the ECMWF model, a"Navy" orography directly from the US Navy data and a "Scripps" orography based on the data set originally compiled several years ago at Scripps. The last two are mean orographies which do not use the envelope enhancement. A new filtering technique for handling the problem of Gibbs oscillations in spectral models has been used to produce the "Navy" and "Scripps" orographies, resulting in smoother fields than the "Standard" orography. The sensitivity experiments show that orography is still an important factor in controlling the model performance even in this class of models that use a semi-lagrangian formulation for water vapour, that in principle should be less sensitive to Gibbs oscillations than the Eulerian formulation. The largest impact can be seen in the stationary waves (asymmetric part of the geopotential at 500 mb where the differences in total height and spatial pattern generate up to 60 m differences, and in the surface fields where the Gibbs removal procedure is successful in alleviating the appearance of unrealistic oscillations over the ocean. These results indicate that Gibbs oscillations also need to be treated in this class of models. The best overall result is obtained using the "Navy" data set, that achieves a good compromise between amplitude of the stationary waves and smoothness of the surface fields.
Spectral effects in low-dose fission and fusion neutron irradiated metals and alloys
International Nuclear Information System (INIS)
Heinisch, H.L.; Atkin, S.D.; Martinez, C.
1986-04-01
Flat miniature tensile specimens were irradiated to neutron fluences up to 9 x 10 22 n/m 2 in the RTNS-II and in the Omega West Reactor. Specimen temperatures were the same in both environments, with runs being made at both 90 0 C and 290 0 C. The results of tensile tests on AISI 316 stainless steel, A302B pressure vessel steel and pure copper are reported here. The radiation-induced changes in yield strength as a function of neutron dose in each spectrum are compared. The data for 316 stainless steel correlate well on the basis of displacements per atom (dpa), while those for copper and A302B do not. In copper the ratio of fission dpa to 14 MeV neutron dpa for a given yield stress change is about three to one. In A302B pressure vessel steel this ratio is more than three at lower fluences, but the yield stress data for fission and 14 MeV neutron-irradiated A302B steel appears to coalesce or intersect at the higher fluences
iSEDfit: Bayesian spectral energy distribution modeling of galaxies
Moustakas, John
2017-08-01
iSEDfit uses Bayesian inference to extract the physical properties of galaxies from their observed broadband photometric spectral energy distribution (SED). In its default mode, the inputs to iSEDfit are the measured photometry (fluxes and corresponding inverse variances) and a measurement of the galaxy redshift. Alternatively, iSEDfit can be used to estimate photometric redshifts from the input photometry alone. After the priors have been specified, iSEDfit calculates the marginalized posterior probability distributions for the physical parameters of interest, including the stellar mass, star-formation rate, dust content, star formation history, and stellar metallicity. iSEDfit also optionally computes K-corrections and produces multiple "quality assurance" (QA) plots at each stage of the modeling procedure to aid in the interpretation of the prior parameter choices and subsequent fitting results. The software is distributed as part of the impro IDL suite.
International Nuclear Information System (INIS)
Noe, N.; Eccher, T.; Signore, E. del; Montoldi, A.
1998-01-01
Plantlets of highbush blueberry (Vaccinium corymbosum) cvs. Atlantic, Barkeley and Elizabeth, were exposed in vitro to radiation of different spectral compositions obtained by filtering the cool-white light. Red colour of leaves was the first response to the light treatments. On average, cv. Atlantic yielded the highest number of shoots per explant (10.4), followed by cv. Elizabeth (9.1) and Berkeley (6.5). No-B-PMMA increased the proliferation rate in all the 3 genotypes, especially in cv. Atlantic. Cutting wavelengths between 650 and 760 nm (no-R-PMMA filter) generally depressed the proliferation rate. No-B-PMMA induced remarkable changes in the morphology of the shoots - more elongate leaves and longer internodes - especially in cv. Atlantic
Spectral analysis and markov switching model of Indonesia business cycle
Fajar, Muhammad; Darwis, Sutawanir; Darmawan, Gumgum
2017-03-01
This study aims to investigate the Indonesia business cycle encompassing the determination of smoothing parameter (λ) on Hodrick-Prescott filter. Subsequently, the components of the filter output cycles were analyzed using a spectral method useful to know its characteristics, and Markov switching regime modeling is made to forecast the probability recession and expansion regimes. The data used in the study is real GDP (1983Q1 - 2016Q2). The results of the study are: a) Hodrick-Prescott filter on real GDP of Indonesia to be optimal when the value of the smoothing parameter is 988.474, b) Indonesia business cycle has amplitude varies between±0.0071 to±0.01024, and the duration is between 4 to 22 quarters, c) the business cycle can be modelled by MSIV-AR (2) but regime periodization is generated this model not perfect exactly with real regime periodzation, and d) Based on the model MSIV-AR (2) obtained long-term probabilities in the expansion regime: 0.4858 and in the recession regime: 0.5142.
Spectral cumulus parameterization based on cloud-resolving model
Baba, Yuya
2018-02-01
We have developed a spectral cumulus parameterization using a cloud-resolving model. This includes a new parameterization of the entrainment rate which was derived from analysis of the cloud properties obtained from the cloud-resolving model simulation and was valid for both shallow and deep convection. The new scheme was examined in a single-column model experiment and compared with the existing parameterization of Gregory (2001, Q J R Meteorol Soc 127:53-72) (GR scheme). The results showed that the GR scheme simulated more shallow and diluted convection than the new scheme. To further validate the physical performance of the parameterizations, Atmospheric Model Intercomparison Project (AMIP) experiments were performed, and the results were compared with reanalysis data. The new scheme performed better than the GR scheme in terms of mean state and variability of atmospheric circulation, i.e., the new scheme improved positive bias of precipitation in western Pacific region, and improved positive bias of outgoing shortwave radiation over the ocean. The new scheme also simulated better features of convectively coupled equatorial waves and Madden-Julian oscillation. These improvements were found to be derived from the modification of parameterization for the entrainment rate, i.e., the proposed parameterization suppressed excessive increase of entrainment, thus suppressing excessive increase of low-level clouds.
Energy Technology Data Exchange (ETDEWEB)
Kortov, V., E-mail: vskortov@mail.ru [Ural Federal University, Mira Str. 19, 620002 Ekaterinburg (Russian Federation); Lushchik, A.; Nagirnyi, V. [Institute of Physics, University of Tartu, W. Ostwald Str. 1, 50411 Tartu (Estonia); Ananchenko, D. [Ural Federal University, Mira Str. 19, 620002 Ekaterinburg (Russian Federation); Romet, I. [Institute of Physics, University of Tartu, W. Ostwald Str. 1, 50411 Tartu (Estonia)
2017-06-15
Thermally stimulated luminescence (TSL) spectra in the 313–580 K temperature range have been studied in anion-defective alumina crystals (named in literature as Al{sub 2}O{sub 3}:C) exposed to different irradiation doses. The TSL curve features two peaks with the maxima at T{sub m1}=437 K and T{sub m2}=565 K. The TSL spectrum of the first peak contains the emission of F centers and the R line of Cr{sup 3+} impurity ions. The absence of the emission of F{sup +} centers indicates that electron traps are responsible for the first dosimetric TSL peak. The TSL spectrum of the second peak features emission bands of F, F{sup +} centers, R line as well as a wide band centered at 550 nm and associated with the formation of aggregate centers (F{sub 2} and F{sub 2}{sup 2+}) under irradiation. Possible excitation mechanisms of the TSL emission bands that involve both electron and hole traps related to anion vacancies and impurities are discussed. - Highlights: •TSL curve of alumina crystals features peaks at 437 and 565 K. •There are emission bands of 410 and 695 nm in the TSL spectrum of the first peak. •TSL spectrum of the second peak features bands of F, F{sub 2}-type centers and the R line of trivalent chromium. •Excitation mechanisms of the emission bands in TSL spectra are discussed.
Modelling a gamma irradiation process using the Monte Carlo method
Energy Technology Data Exchange (ETDEWEB)
Soares, Gabriela A.; Pereira, Marcio T., E-mail: gas@cdtn.br, E-mail: mtp@cdtn.br [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN/CNEN-MG), Belo Horizonte, MG (Brazil)
2011-07-01
In gamma irradiation service it is of great importance the evaluation of absorbed dose in order to guarantee the service quality. When physical structure and human resources are not available for performing dosimetry in each product irradiated, the appliance of mathematic models may be a solution. Through this, the prediction of the delivered dose in a specific product, irradiated in a specific position and during a certain period of time becomes possible, if validated with dosimetry tests. At the gamma irradiation facility of CDTN, equipped with a Cobalt-60 source, the Monte Carlo method was applied to perform simulations of products irradiations and the results were compared with Fricke dosimeters irradiated under the same conditions of the simulations. The first obtained results showed applicability of this method, with a linear relation between simulation and experimental results. (author)
Modelling a gamma irradiation process using the Monte Carlo method
International Nuclear Information System (INIS)
Soares, Gabriela A.; Pereira, Marcio T.
2011-01-01
In gamma irradiation service it is of great importance the evaluation of absorbed dose in order to guarantee the service quality. When physical structure and human resources are not available for performing dosimetry in each product irradiated, the appliance of mathematic models may be a solution. Through this, the prediction of the delivered dose in a specific product, irradiated in a specific position and during a certain period of time becomes possible, if validated with dosimetry tests. At the gamma irradiation facility of CDTN, equipped with a Cobalt-60 source, the Monte Carlo method was applied to perform simulations of products irradiations and the results were compared with Fricke dosimeters irradiated under the same conditions of the simulations. The first obtained results showed applicability of this method, with a linear relation between simulation and experimental results. (author)
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.
International Nuclear Information System (INIS)
Chong, Kok-Keong; Khlyabich, Petr P.; Hong, Kai-Jeat; Reyes-Martinez, Marcos; Rand, Barry P.; Loo, Yueh-Lin
2016-01-01
Highlights: • Method to analyze power-conversion efficiency under various solar irradiance. • Power-conversion efficiency at local irradiance is 5.4% higher than AM1.5G. • Diffuse local irradiance has gain of 23.7–27.9% relative to AM1.5G conditions. • Annual average energy density yield is estimated as 31.89 kW h/m 2 in Malaysia. - Abstract: The solar spectral irradiance varies significantly for different locations and time due to latitude, humidity, cosine effect of incident sunlight, etc. For convenience, the power-conversion efficiency of a solar cell is referenced to the international standard of AM1.5G spectral irradiance, which inevitably leads to varying performance of deployed solar cells under the specific local climate and insolation conditions. To predict the actual performance of solar cells under local climate conditions, we propose a methodology to compute the power-conversion efficiency of organic photovoltaic cells based upon indoor measurement with a solar simulator, the measured local solar spectrum, and making use of both optical and electrical factors. From our study, the annual average energy density yield of poly(3-hexylthiophene):phenyl-C 61 -butyric acid methyl ester (P3HT:PCBM) bulk-heterojunction organic solar cells under the local spectral irradiance of Malaysia is estimated to be 31.89 kW h/m 2 and the power-conversion efficiency is increased by 5.4% compared to that measured under AM1.5G conditions. In addition, diffuse solar irradiance (cloudy condition) was found to be in favor of P3HT:PCBM solar cells, with gain of 23.7–27.9% relative to AM1.5G conditions.
Bracchini, Luca; Dattilo, Arduino Massimo; Falcucci, Margherita; Hull, Vincent; Tognazzi, Antonio; Rossi, Claudio; Loiselle, Steven Arthur
2011-06-01
In deep lakes, water column stratification isolates the surface water from the deeper bottom layers, creating a three dimensional differentiation of the chemical, physical, biological and optical characteristics of the waters. Chromophoric dissolved organic matter (CDOM) and total suspended solids (TSS) play an important role in the attenuation of ultraviolet and photosynthetically active radiation. In the present analysis of spectral irradiance, we show that the wavelength composition of the metalimnetic visible irradiance was influenced by epilimnetic spatial distribution of CDOM. We found a low occurrence of blue-green photons in the metalimnion where epilimnetic concentrations of CDOM are high. In this field study, the spatial variation of the spectral irradiance in the metalimnion correlates with the observed metalimnetic concentrations of chlorophyll a as well as chlorophyll a : chlorophyll b/c ratios. Dissolved oxygen, pH, and nutrients trends suggest that chlorophyll a concentrations were representative of the phytoplankton biomass and primary production. Thus, metalimnetic changes of spectral irradiance may have a direct impact on primary production and an indirect effect on the spatial trends of pH, dissolved oxygen, and inorganic nutrients in the metalimnion.
Modeling irradiation embrittlement in reactor pressure vessel steels
International Nuclear Information System (INIS)
Odette, G.R.
1998-01-01
As a result of the popularity of the Agencies report 'Neutron Irradiation Embrittlement of Reactor Pressure Vessel Steels' of 1975, it was decided that another report on this broad subject would be of use. In this report, background and contemporary views on specially identified areas of the subject are considered as self-contained chapters, written by experts. In chapter 10, numerical modeling of irradiation embrittlement in reactor vessel steels are introduced. Physically-based models are developed and their role in advancing the state-of-the-art of predicting irradiation embrittlement of RPV steels is stressed
Auralization of Accelerating Passenger Cars Using Spectral Modeling Synthesis
Directory of Open Access Journals (Sweden)
Reto Pieren
2015-12-01
Full Text Available While the technique of auralization has been in use for quite some time in architectural acoustics, the application to environmental noise has been discovered only recently. With road traffic noise being the dominant noise source in most countries, particular interest lies in the synthesis of realistic pass-by sounds. This article describes an auralizator for pass-bys of accelerating passenger cars. The key element is a synthesizer that simulates the acoustical emission of different vehicles, driving on different surfaces, under different operating conditions. Audio signals for the emitted tire noise, as well as the propulsion noise are generated using spectral modeling synthesis, which gives complete control of the signal characteristics. The sound of propulsion is synthesized as a function of instantaneous engine speed, engine load and emission angle, whereas the sound of tires is created in dependence of vehicle speed and emission angle. The sound propagation is simulated by applying a series of time-variant digital filters. To obtain the corresponding steering parameters of the synthesizer, controlled experiments were carried out. The tire noise parameters were determined from coast-by measurements of passenger cars with idling engines. To obtain the propulsion noise parameters, measurements at different engine speeds, engine loads and emission angles were performed using a chassis dynamometer. The article shows how, from the measured data, the synthesizer parameters are calculated using audio signal processing.
A Statistical and Spectral Model for Representing Noisy Sounds with Short-Time Sinusoids
Directory of Open Access Journals (Sweden)
Myriam Desainte-Catherine
2005-07-01
Full Text Available We propose an original model for noise analysis, transformation, and synthesis: the CNSS model. Noisy sounds are represented with short-time sinusoids whose frequencies and phases are random variables. This spectral and statistical model represents information about the spectral density of frequencies. This perceptually relevant property is modeled by three mathematical parameters that define the distribution of the frequencies. This model also represents the spectral envelope. The mathematical parameters are defined and the analysis algorithms to extract these parameters from sounds are introduced. Then algorithms for generating sounds from the parameters of the model are presented. Applications of this model include tools for composers, psychoacoustic experiments, and pedagogy.
Galy, N.; Toulhoat, N.; Moncoffre, N.; Pipon, Y.; Bérerd, N.; Ammar, M. R.; Simon, P.; Deldicque, D.; Sainsot, P.
2017-10-01
Due to its excellent moderator and reflector qualities, graphite was used in CO2-cooled nuclear reactors such as UNGG (Uranium Naturel-Graphite-Gaz). Neutron irradiation of graphite resulted in the production of 14C which is a key issue radionuclide for the management of the irradiated graphite waste. In order to elucidate the impact of neutron irradiation on 14C behavior, we carried out a systematic investigation of irradiation and its synergistic effects with temperature in Highly Oriented Pyrolitic Graphite (HOPG) model graphite used to simulate the coke grains of nuclear graphite. We used 13C implantation in order to simulate 14C displaced from its original structural site through recoil. The collision of the impinging neutrons with the graphite matrix carbon atoms induces mainly ballistic damage. However, a part of the recoil carbon atom energy is also transferred to the graphite lattice through electronic excitation. The effects of the different irradiation regimes in synergy with temperature were simulated using ion irradiation by varying Sn(nuclear)/Se(electronic) stopping power. Thus, the samples were irradiated with different ions of different energies. The structure modifications were followed by High Resolution Transmission Electron Microscopy (HRTEM) and Raman microspectrometry. The results show that temperature generally counteracts the disordering effects of irradiation but the achieved reordering level strongly depends on the initial structural state of the graphite matrix. Thus, extrapolating to reactor conditions, for an initially highly disordered structure, irradiation at reactor temperatures (200 - 500 °C) should induce almost no change of the initial structure. On the contrary, when the structure is initially less disordered, there should be a "zoning" of the reordering: In "cold" high flux irradiated zones where the ballistic damage is important, the structure should be poorly reordered; In "hot" low flux irradiated zones where the ballistic
Measurements and modeling of total solar irradiance in X-class solar flares
International Nuclear Information System (INIS)
Moore, Christopher Samuel; Chamberlin, Phillip Clyde; Hock, Rachel
2014-01-01
The Total Irradiance Monitor (TIM) from NASA's SOlar Radiation and Climate Experiment can detect changes in the total solar irradiance (TSI) to a precision of 2 ppm, allowing observations of variations due to the largest X-class solar flares for the first time. Presented here is a robust algorithm for determining the radiative output in the TIM TSI measurements, in both the impulsive and gradual phases, for the four solar flares presented in Woods et al., as well as an additional flare measured on 2006 December 6. The radiative outputs for both phases of these five flares are then compared to the vacuum ultraviolet (VUV) irradiance output from the Flare Irradiance Spectral Model (FISM) in order to derive an empirical relationship between the FISM VUV model and the TIM TSI data output to estimate the TSI radiative output for eight other X-class flares. This model provides the basis for the bolometric energy estimates for the solar flares analyzed in the Emslie et al. study.
Design, Construction, and Modeling of a 252Cf Neutron Irradiator
Directory of Open Access Journals (Sweden)
Blake C. Anderson
2016-01-01
Full Text Available Neutron production methods are an integral part of research and analysis for an array of applications. This paper examines methods of neutron production, and the advantages of constructing a radioisotopic neutron irradiator assembly using 252Cf. Characteristic neutron behavior and cost-benefit comparative analysis between alternative modes of neutron production are also examined. The irradiator is described from initial conception to the finished design. MCNP modeling shows a total neutron flux of 3 × 105 n/(cm2·s in the irradiation chamber for a 25 μg source. Measurements of the gamma-ray and neutron dose rates near the external surface of the irradiator assembly are 120 μGy/h and 30 μSv/h, respectively, during irradiation. At completion of the project, total material, and labor costs remained below $50,000.
Crystal plasticity modeling of irradiation growth in Zircaloy-2
Patra, Anirban; Tomé, Carlos N.; Golubov, Stanislav I.
2017-08-01
A physically based reaction-diffusion model is implemented in the visco-plastic self-consistent (VPSC) crystal plasticity framework to simulate irradiation growth in hcp Zr and its alloys. The reaction-diffusion model accounts for the defects produced by the cascade of displaced atoms, their diffusion to lattice sinks and the contribution to crystallographic strain at the level of single crystals. The VPSC framework accounts for intergranular interactions and irradiation creep, and calculates the strain in the polycrystalline ensemble. A novel scheme is proposed to model the simultaneous evolution of both, number density and radius, of irradiation-induced dislocation loops directly from experimental data of dislocation density evolution during irradiation. This framework is used to predict the irradiation growth behaviour of cold-worked Zircaloy-2 and trends compared to available experimental data. The role of internal stresses in inducing irradiation creep is discussed. Effects of grain size, texture and external stress on the coupled irradiation growth and creep behaviour are also studied and compared with available experimental data.
Modelled basic parameters for semi-industrial irradiation plant design
International Nuclear Information System (INIS)
Mangussi, J.
2009-01-01
The basic parameters of an irradiation plant design are the total activity, the product uniformity ratio and the efficiency process. The target density, the minimum dose required and the throughput depends on the use to which the irradiator will be put at. In this work, a model for calculating the specific dose rate at several depths in an infinite homogeneous medium produced by a slab source irradiator is presented. The product minimum dose rate for a set of target thickness is obtained. The design method steps are detailed and an illustrative example is presented. (author)
International Nuclear Information System (INIS)
Melent'ev, A.B.; Frid, E.S.; Shekhanov, G.A.; Zhitnik, A.K.; Shanenko, A.A.
1992-01-01
The analysis and calculated-experimental investigations were presented. The tipified conditions for irradiation of the equipment and the personnel as the result of destroys in the Chernobyl' NPP and initial data of spectral-angular parameters of gamma radiated sites were proposed. The results of the investigation may be used in the prediction of radiation effect on the personnel as well as during design and estimation of the effective protection from gamma radiation. 3 refs.; 7 refs
The spectral cell method in nonlinear earthquake modeling
Giraldo, Daniel; Restrepo, Doriam
2017-12-01
This study examines the applicability of the spectral cell method (SCM) to compute the nonlinear earthquake response of complex basins. SCM combines fictitious-domain concepts with the spectral-version of the finite element method to solve the wave equations in heterogeneous geophysical domains. Nonlinear behavior is considered by implementing the Mohr-Coulomb and Drucker-Prager yielding criteria. We illustrate the performance of SCM with numerical examples of nonlinear basins exhibiting physically and computationally challenging conditions. The numerical experiments are benchmarked with results from overkill solutions, and using MIDAS GTS NX, a finite element software for geotechnical applications. Our findings show good agreement between the two sets of results. Traditional spectral elements implementations allow points per wavelength as low as PPW = 4.5 for high-order polynomials. Our findings show that in the presence of nonlinearity, high-order polynomials (p ≥ 3) require mesh resolutions above of PPW ≥ 10 to ensure displacement errors below 10%.
Spectral functions for the flat plasma sheet model
International Nuclear Information System (INIS)
Pirozhenko, I G
2006-01-01
The present work is based on Bordag M et al 2005 (J. Phys. A: Math. Gen. 38 11027) where the spectral analysis of the electromagnetic field on the background of an infinitely thin flat plasma layer is carried out. The solutions to Maxwell equations with the appropriate matching conditions at the plasma layer are derived and the spectrum of electromagnetic oscillations is determined. The spectral zeta function and the integrated heat kernel are constructed for different branches of the spectrum in an explicit form. The asymptotic expansion of the integrated heat kernel at small values of the evolution parameter is derived. The local heat kernels are considered also
AMARSI: Aerosol modeling and retrieval from multi-spectral imagers
Leeuw, G. de; Curier, R.L.; Staroverova, A.; Kokhanovsky, A.; Hoyningen-Huene, W. van; Rozanov, V.V.; Burrows, J.P.; Hesselmans, G.; Gale, L.; Bouvet, M.
2008-01-01
The AMARSI project aims at the development and validation of aerosol retrieval algorithms over ocean. One algorithm will be developed for application with data from the Multi Spectral Imager (MSI) on EarthCARE. A second algorithm will be developed using the combined information from AATSR and MERIS,
Pervasive randomness in physics: an introduction to its modelling and spectral characterisation
Howard, Roy
2017-10-01
An introduction to the modelling and spectral characterisation of random phenomena is detailed at a level consistent with a first exposure to the subject at an undergraduate level. A signal framework for defining a random process is provided and this underpins an introduction to common random processes including the Poisson point process, the random walk, the random telegraph signal, shot noise, information signalling random processes, jittered pulse trains, birth-death random processes and Markov chains. An introduction to the spectral characterisation of signals and random processes, via either an energy spectral density or a power spectral density, is detailed. The important case of defining a white noise random process concludes the paper.
Energy Technology Data Exchange (ETDEWEB)
Roushdy, H; Pierotti, T; Polverelli, M [Commissariat a l' Energie Atomique, Grenoble (France). Centre d' Etudes Nucleaires
1969-07-01
Imidazole and benzimidazole are known for their radioprotective action. In this work, authors have studied the radioprotective action of these compounds on visible and ultra-violet hemoglobin absorption spectra obtained from mice after in vivo X-irradiation. Results compared to those obtained with cysteamine show: 1- a possible pharmacological action of the heterocyclic nitrogenous compounds on the {alpha} and {beta} bands (540 and 580 m{mu}). 2 - a significative variation of the ratio of the optical densities (580/540) after irradiation with hemoglobin of non and radio-protected mice. However, following a real drop of absorption maxima, the twenty-fifth day after irradiation, normal optical densities of each band are found again. A physico-chemical study would be necessary to understand the hemoglobin transformation after irradiation and perhaps, its possible radioprotection. (authors) [French] Les proprietes radioprotectrices de l'imidazole et du benzimidazole etant deja connues, les auteurs ont etudie l'action de ces produits sur les spectres d'absorption de l'hemoglobine dans le visible et le proche ultra-violet apres une irradiation in vivo de souris a dose letale. L'action de ces produits comparee a celle de la cysteamine utilisee dans les memes conditions a permis de constater: 1- l'action pharmacologique probable des heterocycles azotes sur les bandes {alpha} et {beta} situees a 540 et 580 m{mu}; 2 - qu'avec et sans radioprotecteurs, les modifications spectrales se traduisaient par des variations du rapport d'intensite d'absorption existant entre les bandes a 540 et 580 m{mu}. Toutefois, apres une chute des maxima d'absorption, ceux-ci retournent aux valeurs normales le vingt-cinquieme jour apres irradiation. Une etude physicochimique complementaire de l'hemoglobine permettrait de definir la nature exacte du changement apres irradiation et peut-etre son eventuelle radioprotection. (auteurs)
Modeling of coated fuel particles irradiation behavior
International Nuclear Information System (INIS)
Liang Tongxiang; Phelip, M.
2006-01-01
In this report, PANAMA code was used to estimate the CP performance under normal and accident condition. Under the normal irradiation test (1000 degree C 625 efpd, 10% FIMA), for intact CP fuel, failure fraction is in the level of 10 -7 . As-fabricated SiC failed particles results in the through coatings failed particles much earlier than the intact particles does, OPyC layer does not fail immediately after irradiation starts. The significant failures start at beyond the burnup of about 7% FIMA. Under the accident condition, the calculated results showed that when the heating temperature is much higher than 1850 degree C, the failure fraction of coated particle can reach the level of 1 percent. The CP fuel fails significantly if it has a buffer layer thinner than 65 urn, SiC layer thinner than 30 μm. High burnup CP need to develop small size kernel, thick buffer layer and thick SiC layer. (authors)
Dose rate modelled for the outdoors of a gamma irradiation
International Nuclear Information System (INIS)
Mangussi, J
2012-01-01
A model for the absorbed dose rate calculation on the surroundings of a gamma irradiation plant is developed. In such plants, a part of the radiation emitted upwards reach's the outdoors. The Compton scatterings on the wall of the exhausting pipes through de plant roof and on the outdoors air are modelled. The absorbed dose rate generated by the scattered radiation as far as 200 m is calculated. The results of the models, to be used for the irradiation plant design and for the environmental studies, are showed on graphics (author)
Modelling Ultraviolet Irradiance in South Africa
International Nuclear Information System (INIS)
Human, S.; Bajic, V.
2000-01-01
South Africa (SA) is a country with a variety of climatic regions and topological diversity. The southernmost town in SA, Cape Agulhas (34 S, 19 E), is on about the same latitude as Perth and Sydney in Australia. UV (author)ivity. Hthan 10 are common in SA. This high level of UV radiation potentially causes many health problems resulting in high rates of skin cancer, eye disorders etc. A method is presented for inferring a level of UV irradiance from imprecise measurements. The method uses nine measured or estimated variables to infer the UV index. It employs a system of five artificial neural networks to convert the information contained in measured/estimated data into the UV index. The results obtained are of considerable statistical significance. It should be mentioned that the other statistical techniques used, such as linear and/or non-linear regression, did not produce satisfactory results. (author)
Modelling Ultraviolet Irradiance in South Africa
Energy Technology Data Exchange (ETDEWEB)
Human, S.; Bajic, V
2000-07-01
South Africa (SA) is a country with a variety of climatic regions and topological diversity. The southernmost town in SA, Cape Agulhas (34 S, 19 E), is on about the same latitude as Perth and Sydney in Australia. UV (author)ivity. Hthan 10 are common in SA. This high level of UV radiation potentially causes many health problems resulting in high rates of skin cancer, eye disorders etc. A method is presented for inferring a level of UV irradiance from imprecise measurements. The method uses nine measured or estimated variables to infer the UV index. It employs a system of five artificial neural networks to convert the information contained in measured/estimated data into the UV index. The results obtained are of considerable statistical significance. It should be mentioned that the other statistical techniques used, such as linear and/or non-linear regression, did not produce satisfactory results. (author)
Measurement and modeling of shortwave irradiance components in cloud-free atmospheres
Energy Technology Data Exchange (ETDEWEB)
Halthore, R.N.
1999-08-04
Atmosphere scatters and absorbs incident solar radiation modifying its spectral content and decreasing its intensity at the surface. It is very useful to classify the earth-atmospheric solar radiation into several components--direct solar surface irradiance (E{sub direct}), diffuse-sky downward surface irradiance (E{sub diffuse}), total surface irradiance, and upwelling flux at the surface and at the top-of-the atmosphere. E{sub direct} depends only on the extinction properties of the atmosphere without regard to details of extinction, namely scattering or absorption; furthermore it can be accurately measured to high accuracy (0.3%) with the aid of an active cavity radiometer (ACR). E{sub diffuse} has relatively larger uncertainties both in its measurement using shaded pyranometers and in model estimates, owing to the difficulty in accurately characterizing pyranometers and in measuring model inputs such as surface reflectance, aerosol single scattering albedo, and phase function. Radiative transfer model simulations of the above surface radiation components in cloud-free skies using measured atmospheric properties show that while E{sub direct} estimates are closer to measurements, E{sub diffuse} is overestimated by an amount larger than the combined uncertainties in model inputs and measurements, illustrating a fundamental gap in the understanding of the magnitude of atmospheric absorption in cloud-free skies. The excess continuum type absorption required to reduce the E{sub diffuse} model overestimate ({approximately}3--8% absorptance) would significantly impact climate prediction and remote sensing. It is not clear at present what the source for this continuum absorption is. Here issues related to measurements and modeling of the surface irradiance components are discussed.
PHOTOMETRIC AND SPECTRAL SIGNATURES OF THREE-DIMENSIONAL MODELS OF TRANSITING GIANT EXOPLANETS
International Nuclear Information System (INIS)
Burrows, A.; Spiegel, D. S.; Rauscher, E.; Menou, K.
2010-01-01
Using a three-dimensional general circulation model, we create dynamical model atmospheres of a representative transiting giant exoplanet, HD 209458b. We post-process these atmospheres with an opacity code to obtain transit radius spectra during the primary transit. Using a spectral atmosphere code, we integrate over the face of the planet seen by an observer at various orbital phases and calculate light curves as a function of wavelength and for different photometric bands. The products of this study are generic predictions for the phase variations of a zero-eccentricity giant planet's transit spectrum and of its light curves. We find that for these models the temporal variations in all quantities and the ingress/egress contrasts in the transit radii are small (<1.0%). Moreover, we determine that the day/night contrasts and phase shifts of the brightness peaks relative to the ephemeris are functions of photometric band. The J, H, and K bands are shifted most, while the IRAC bands are shifted least. Therefore, we verify that the magnitude of the downwind shift in the planetary 'hot spot' due to equatorial winds is strongly wavelength dependent. The phase and wavelength dependence of light curves, as well as the associated day/night contrasts, can be used to constrain the circulation regime of irradiated giant planets and to probe different pressure levels of a hot Jupiter atmosphere. We posit that though our calculations focus on models of HD 209458b, similar calculations for other transiting hot Jupiters in low-eccentricity orbits should yield transit spectra and light curves of a similar character.
Meso-scale modeling of irradiated concrete in test reactor
International Nuclear Information System (INIS)
Giorla, A.; Vaitová, M.; Le Pape, Y.; Štemberk, P.
2015-01-01
Highlights: • A meso-scale finite element model for irradiated concrete is developed. • Neutron radiation-induced volumetric expansion is a predominant degradation mode. • Confrontation with expansion and damage obtained from experiments is successful. • Effects of paste shrinkage, creep and ductility are discussed. - Abstract: A numerical model accounting for the effects of neutron irradiation on concrete at the mesoscale is detailed in this paper. Irradiation experiments in test reactor (Elleuch et al., 1972), i.e., in accelerated conditions, are simulated. Concrete is considered as a two-phase material made of elastic inclusions (aggregate) subjected to thermal and irradiation-induced swelling and embedded in a cementitious matrix subjected to shrinkage and thermal expansion. The role of the hardened cement paste in the post-peak regime (brittle-ductile transition with decreasing loading rate), and creep effects are investigated. Radiation-induced volumetric expansion (RIVE) of the aggregate cause the development and propagation of damage around the aggregate which further develops in bridging cracks across the hardened cement paste between the individual aggregate particles. The development of damage is aggravated when shrinkage occurs simultaneously with RIVE during the irradiation experiment. The post-irradiation expansion derived from the simulation is well correlated with the experimental data and, the obtained damage levels are fully consistent with previous estimations based on a micromechanical interpretation of the experimental post-irradiation elastic properties (Le Pape et al., 2015). The proposed modeling opens new perspectives for the interpretation of test reactor experiments in regards to the actual operation of light water reactors.
Meso-scale modeling of irradiated concrete in test reactor
Energy Technology Data Exchange (ETDEWEB)
Giorla, A. [Oak Ridge National Laboratory, One Bethel Valley Road, Oak Ridge, TN 37831 (United States); Vaitová, M. [Czech Technical University, Thakurova 7, 166 29 Praha 6 (Czech Republic); Le Pape, Y., E-mail: lepapeym@ornl.gov [Oak Ridge National Laboratory, One Bethel Valley Road, Oak Ridge, TN 37831 (United States); Štemberk, P. [Czech Technical University, Thakurova 7, 166 29 Praha 6 (Czech Republic)
2015-12-15
Highlights: • A meso-scale finite element model for irradiated concrete is developed. • Neutron radiation-induced volumetric expansion is a predominant degradation mode. • Confrontation with expansion and damage obtained from experiments is successful. • Effects of paste shrinkage, creep and ductility are discussed. - Abstract: A numerical model accounting for the effects of neutron irradiation on concrete at the mesoscale is detailed in this paper. Irradiation experiments in test reactor (Elleuch et al., 1972), i.e., in accelerated conditions, are simulated. Concrete is considered as a two-phase material made of elastic inclusions (aggregate) subjected to thermal and irradiation-induced swelling and embedded in a cementitious matrix subjected to shrinkage and thermal expansion. The role of the hardened cement paste in the post-peak regime (brittle-ductile transition with decreasing loading rate), and creep effects are investigated. Radiation-induced volumetric expansion (RIVE) of the aggregate cause the development and propagation of damage around the aggregate which further develops in bridging cracks across the hardened cement paste between the individual aggregate particles. The development of damage is aggravated when shrinkage occurs simultaneously with RIVE during the irradiation experiment. The post-irradiation expansion derived from the simulation is well correlated with the experimental data and, the obtained damage levels are fully consistent with previous estimations based on a micromechanical interpretation of the experimental post-irradiation elastic properties (Le Pape et al., 2015). The proposed modeling opens new perspectives for the interpretation of test reactor experiments in regards to the actual operation of light water reactors.
Computational model of gamma irradiation room at ININ
Rodríguez-Romo, Suemi; Patlan-Cardoso, Fernando; Ibáñez-Orozco, Oscar; Vergara Martínez, Francisco Javier
2018-03-01
In this paper, we present a model of the gamma irradiation room at the National Institute of Nuclear Research (ININ is its acronym in Spanish) in Mexico to improve the use of physics in dosimetry for human protection. We deal with air-filled ionization chambers and scientific computing made in house and framed in both the GEANT4 scheme and our analytical approach to characterize the irradiation room. This room is the only secondary dosimetry facility in Mexico. Our aim is to optimize its experimental designs, facilities, and industrial applications of physical radiation. The computational results provided by our model are supported by all the known experimental data regarding the performance of the ININ gamma irradiation room and allow us to predict the values of the main variables related to this fully enclosed space to within an acceptable margin of error.
Computational Modeling of Ablation on an Irradiated Target
Mehmedagic, Igbal; Thangam, Siva
2017-11-01
Computational modeling of pulsed nanosecond laser interaction with an irradiated metallic target is presented. The model formulation involves ablation of the metallic target irradiated by pulsed high intensity laser at normal atmospheric conditions. Computational findings based on effective representation and prediction of the heat transfer, melting and vaporization of the targeting material as well as plume formation and expansion are presented along with its relevance for the development of protective shields. In this context, the available results for a representative irradiation from 1064 nm laser pulse is used to analyze various ablation mechanisms, variable thermo-physical and optical properties, plume expansion and surface geometry. Funded in part by U. S. Army ARDEC, Picatinny Arsenal, NJ.
Tahani, K.; Plume, R.; Bergin, E. A.; Tolls, V.; Phillips, T. G.; Caux, E.; Cabrit, S.; Goicoechea, J. R.; Goldsmith, P. F.; Johnstone, D.; Lis, D. C.; Pagani, L.; Menten, K. M.; Müller, H. S. P.; Ossenkopf-Okada, V.; Pearson, J. C.; van der Tak, F. F. S.
2016-01-01
We present results from a comprehensive submillimeter spectral survey toward the source Orion South, based on data obtained with the Heterodyne Instrument for the Far-Infrared instrument on board the Herschel Space Observatory, covering the frequency range of 480 to 1900 GHz. We detect 685 spectral
Regression Model to Predict Global Solar Irradiance in Malaysia
Directory of Open Access Journals (Sweden)
Hairuniza Ahmed Kutty
2015-01-01
Full Text Available A novel regression model is developed to estimate the monthly global solar irradiance in Malaysia. The model is developed based on different available meteorological parameters, including temperature, cloud cover, rain precipitate, relative humidity, wind speed, pressure, and gust speed, by implementing regression analysis. This paper reports on the details of the analysis of the effect of each prediction parameter to identify the parameters that are relevant to estimating global solar irradiance. In addition, the proposed model is compared in terms of the root mean square error (RMSE, mean bias error (MBE, and the coefficient of determination (R2 with other models available from literature studies. Seven models based on single parameters (PM1 to PM7 and five multiple-parameter models (PM7 to PM12 are proposed. The new models perform well, with RMSE ranging from 0.429% to 1.774%, R2 ranging from 0.942 to 0.992, and MBE ranging from −0.1571% to 0.6025%. In general, cloud cover significantly affects the estimation of global solar irradiance. However, cloud cover in Malaysia lacks sufficient influence when included into multiple-parameter models although it performs fairly well in single-parameter prediction models.
Data Field Modeling and Spectral-Spatial Feature Fusion for Hyperspectral Data Classification.
Liu, Da; Li, Jianxun
2016-12-16
Classification is a significant subject in hyperspectral remote sensing image processing. This study proposes a spectral-spatial feature fusion algorithm for the classification of hyperspectral images (HSI). Unlike existing spectral-spatial classification methods, the influences and interactions of the surroundings on each measured pixel were taken into consideration in this paper. Data field theory was employed as the mathematical realization of the field theory concept in physics, and both the spectral and spatial domains of HSI were considered as data fields. Therefore, the inherent dependency of interacting pixels was modeled. Using data field modeling, spatial and spectral features were transformed into a unified radiation form and further fused into a new feature by using a linear model. In contrast to the current spectral-spatial classification methods, which usually simply stack spectral and spatial features together, the proposed method builds the inner connection between the spectral and spatial features, and explores the hidden information that contributed to classification. Therefore, new information is included for classification. The final classification result was obtained using a random forest (RF) classifier. The proposed method was tested with the University of Pavia and Indian Pines, two well-known standard hyperspectral datasets. The experimental results demonstrate that the proposed method has higher classification accuracies than those obtained by the traditional approaches.
Development of irradiated UO2 thermal conductivity model
International Nuclear Information System (INIS)
Lee, Chan Bock; Bang Je-Geon; Kim Dae Ho; Jung Youn Ho
2001-01-01
Thermal conductivity model of the irradiated UO 2 pellet was developed, based upon the thermal diffusivity data of the irradiated UO 2 pellet measured during thermal cycling. The model predicts the thermal conductivity by multiplying such separate correction factors as solid fission products, gaseous fission products, radiation damage and porosity. The developed model was validated by comparison with the variation of the measured thermal diffusivity data during thermal cycling and prediction of other UO 2 thermal conductivity models. Since the developed model considers the effect of gaseous fission products as a separate factor, it can predict variation of thermal conductivity in the rim region of high burnup UO 2 pellet where the fission gases in the matrix are precipitated into bubbles, indicating that decrease of thermal conductivity by bubble precipitation in rim region would be significantly compensated by the enhancing effect of fission gas depletion in the UO 2 matrix. (author)
Irradiation Design for an Experimental Murine Model
International Nuclear Information System (INIS)
Ballesteros-Zebadua, P.; Moreno-Jimenez, S.; Suarez-Campos, J. E.; Celis, M. A.; Larraga-Gutierrez, J. M.; Garcia-Garduno, O. A.; Rubio-Osornio, M. C.; Custodio-Ramirez, V.; Paz, C.
2010-01-01
In radiotherapy and stereotactic radiosurgery, small animal experimental models are frequently used, since there are still a lot of unsolved questions about the biological and biochemical effects of ionizing radiation. This work presents a method for small-animal brain radiotherapy compatible with a dedicated 6MV Linac. This rodent model is focused on the research of the inflammatory effects produced by ionizing radiation in the brain. In this work comparisons between Pencil Beam and Monte Carlo techniques, were used in order to evaluate accuracy of the calculated dose using a commercial planning system. Challenges in this murine model are discussed.
Post-irradiation annealing of coarse-grained model alloys
Energy Technology Data Exchange (ETDEWEB)
Ray, P H.N.; Wilson, C; McElroy, R J [AEA Reactor Services, Harwell (United Kingdom)
1994-12-31
Thermal ageing and irradiation studies have been carried out on three model alloys (JPC, JPB, JPG) that have identical compositions except for different levels of phosphorus and/or copper. They have been irradiated in three conditions, as-received, heat treated to produce a coarse grained microstructure (similar to heat-affected-zone), and in this condition further aged at 450 C to produce a temper embrittled condition. One of the alloy have been subject to a post-irradiation anneal. The effect of these treatments on mechanical property changes has been characterized by Charpy testing and Vickers hardness measurements; the phosphorus segregation has been studied by a combination of STEM and Auger techniques.
Energy Technology Data Exchange (ETDEWEB)
Fat’yanov, O. V., E-mail: fatyan1@gps.caltech.edu; Asimow, P. D., E-mail: asimow@gps.caltech.edu [Division of Geological and Planetary Sciences 252-21, California Institute of Technology, Pasadena, California 91125 (United States)
2015-10-15
We describe an accurate and precise calibration procedure for multichannel optical pyrometers such as the 6-channel, 3-ns temporal resolution instrument used in the Caltech experimental geophysics laboratory. We begin with a review of calibration sources for shock temperatures in the 3000-30 000 K range. High-power, coiled tungsten halogen standards of spectral irradiance appear to be the only practical alternative to NIST-traceable tungsten ribbon lamps, which are no longer available with large enough calibrated area. However, non-uniform radiance complicates the use of such coiled lamps for reliable and reproducible calibration of pyrometers that employ imaging or relay optics. Careful analysis of documented methods of shock pyrometer calibration to coiled irradiance standard lamps shows that only one technique, not directly applicable in our case, is free of major radiometric errors. We provide a detailed description of the modified Caltech pyrometer instrument and a procedure for its absolute spectral radiance calibration, accurate to ±5%. We employ a designated central area of a 0.7× demagnified image of a coiled-coil tungsten halogen lamp filament, cross-calibrated against a NIST-traceable tungsten ribbon lamp. We give the results of the cross-calibration along with descriptions of the optical arrangement, data acquisition, and processing. We describe a procedure to characterize the difference between the static and dynamic response of amplified photodetectors, allowing time-dependent photodiode correction factors for spectral radiance histories from shock experiments. We validate correct operation of the modified Caltech pyrometer with actual shock temperature experiments on single-crystal NaCl and MgO and obtain very good agreement with the literature data for these substances. We conclude with a summary of the most essential requirements for error-free calibration of a fiber-optic shock-temperature pyrometer using a high-power coiled tungsten halogen
Spectral modeling of laser-produced underdense titanium plasmas
Chung, Hyun-Kyung; Back, Christina A.; Scott, Howard A.; Constantin, Carmen; Lee, Richard W.
2004-11-01
Experiments were performed at the NIKE laser to create underdense low-Z plasmas with a small amount of high-Z dopant in order to study non-LTE population kinetics. An absolutely calibrated spectra in 470-3000 eV was measured in time-resolved and time-averaged fashion from SiO2 aerogel target with 3% Ti dopant. K-shell Ti emission was observed as well as L-shell Ti emission. Time-resolved emission show that lower energy photons peak later than higher energy photons due to plasma cooling. In this work, we compare the measured spectra with non-LTE spectral calculations of titanium emission at relatively low temperatures distributions dominated by L-shell ions will be discussed.
Aron, Miles; Browning, Richard; Carugo, Dario; Sezgin, Erdinc; Bernardino de la Serna, Jorge; Eggeling, Christian; Stride, Eleanor
2017-05-12
Spectral imaging with polarity-sensitive fluorescent probes enables the quantification of cell and model membrane physical properties, including local hydration, fluidity, and lateral lipid packing, usually characterized by the generalized polarization (GP) parameter. With the development of commercial microscopes equipped with spectral detectors, spectral imaging has become a convenient and powerful technique for measuring GP and other membrane properties. The existing tools for spectral image processing, however, are insufficient for processing the large data sets afforded by this technological advancement, and are unsuitable for processing images acquired with rapidly internalized fluorescent probes. Here we present a MATLAB spectral imaging toolbox with the aim of overcoming these limitations. In addition to common operations, such as the calculation of distributions of GP values, generation of pseudo-colored GP maps, and spectral analysis, a key highlight of this tool is reliable membrane segmentation for probes that are rapidly internalized. Furthermore, handling for hyperstacks, 3D reconstruction and batch processing facilitates analysis of data sets generated by time series, z-stack, and area scan microscope operations. Finally, the object size distribution is determined, which can provide insight into the mechanisms underlying changes in membrane properties and is desirable for e.g. studies involving model membranes and surfactant coated particles. Analysis is demonstrated for cell membranes, cell-derived vesicles, model membranes, and microbubbles with environmentally-sensitive probes Laurdan, carboxyl-modified Laurdan (C-Laurdan), Di-4-ANEPPDHQ, and Di-4-AN(F)EPPTEA (FE), for quantification of the local lateral density of lipids or lipid packing. The Spectral Imaging Toolbox is a powerful tool for the segmentation and processing of large spectral imaging datasets with a reliable method for membrane segmentation and no ability in programming required. The
Modelling irradiation effects in fusion materials
DEFF Research Database (Denmark)
Victoria, M.; Dudarev, S.; Boutard, J.L.
2007-01-01
We review the current status of the European fusion materials modelling programme. We describe recent findings and outline potential areas for future development. Large-scale density functional theory (DFT) calculations reveal the structure of the point defects in α-Fe, and highlight the crucial...
A mixed spectral-integration model for neutral mean wind flow over hills
DEFF Research Database (Denmark)
Corbett, Jean-Francois; Ott, Søren; Landberg, Lars
2008-01-01
equations are solved spectrally horizontally and by numerical integration vertically. Non-dimensional solutions are stored in look-up tables for quick re-use. Model results are compared to measurements, as well as other authors' flow models in three test cases. The model is implemented and tested in two...
DEFF Research Database (Denmark)
Chougule, Abhijit S.; Mann, Jakob; Kelly, Mark C.
2017-01-01
A spectral tensor model is presented for turbulent fluctuations of wind velocity components and temperature, assuming uniform vertical gradients in mean temperature and mean wind speed. The model is built upon rapid distortion theory (RDT) following studies by Mann and by Hanazaki and Hunt, using...... the eddy lifetime parameterization of Mann to make the model stationary. The buoyant spectral tensor model is driven via five parameters: the viscous dissipation rate epsilon, length scale of energy-containing eddies L, a turbulence anisotropy parameter Gamma, gradient Richardson number (Ri) representing...
Brooks, Adam J; Yao, Zhongwen
2017-10-01
The data presented in this article is related to the research experiment, titled: ' Quasi in-situ energy dispersive X-ray spectroscopy observation of matrix and solute interactions on Y-Ti-O oxide particles in an austenitic stainless steel under 1 MeV Kr 2+ high temperature irradiation' (Brooks et al., 2017) [1]. Quasi in-situ analysis during 1 MeV Kr 2+ 520 °C irradiation allowed the same microstructural area to be observed using a transmission electron microscope (TEM), on an oxide dispersion strengthened (ODS) austenitic stainless steel sample. The data presented contains two sets of energy dispersive X-ray spectroscopy (EDX) data collected before and after irradiation to 1.5 displacements-per-atom (~1.25×10 -3 dpa/s with 7.5×10 14 ions cm -2 ). The vendor software used to process and output the data is the Bruker Esprit v1.9 suite. The data includes the spectral (counts vs. keV energy) of the quasi in-situ scanned region (512×512 pixels at 56k magnification), along with the EDX scanning parameters. The.raw files from the Bruker Esprit v1.9 output are additionally included along with the.rpl data information files. Furthermore included are the two quasi in-situ HAADF images for visual comparison of the regions before and after irradiation. This in-situ experiment is deemed ' quasi' due to the thin foil irradiation taking place at an external TEM facility. We present this data for critical and/or extended analysis from the scientific community, with applications applying to: experimental data correlation, confirmation of results, and as computer based modeling inputs.
Barrett, K.; Kasischke, E. S.; McGuire, A. D.; Turetsky, M. R.; Kane, E. S.
2010-01-01
Biomass burning in the Alaskan interior is already a major disturbance and source of carbon emissions, and is likely to increase in response to the warming and drying predicted for the future climate. In addition to quantifying changes to the spatial and temporal patterns of burned areas, observing variations in severity is the key to studying the impact of changes to the fire regime on carbon cycling, energy budgets, and post-fire succession. Remote sensing indices of fire severity have not consistently been well-correlated with in situ observations of important severity characteristics in Alaskan black spruce stands, including depth of burning of the surface organic layer. The incorporation of ancillary data such as in situ observations and GIS layers with spectral data from Landsat TM/ETM+ greatly improved efforts to map the reduction of the organic layer in burned black spruce stands. Using a regression tree approach, the R2 of the organic layer depth reduction models was 0.60 and 0.55 (pb0.01) for relative and absolute depth reduction, respectively. All of the independent variables used by the regression tree to estimate burn depth can be obtained independently of field observations. Implementation of a gradient boosting algorithm improved the R2 to 0.80 and 0.79 (pb0.01) for absolute and relative organic layer depth reduction, respectively. Independent variables used in the regression tree model of burn depth included topographic position, remote sensing indices related to soil and vegetation characteristics, timing of the fire event, and meteorological data. Post-fire organic layer depth characteristics are determined for a large (N200,000 ha) fire to identify areas that are potentially vulnerable to a shift in post-fire succession. This application showed that 12% of this fire event experienced fire severe enough to support a change in post-fire succession. We conclude that non-parametric models and ancillary data are useful in the modeling of the surface
Directory of Open Access Journals (Sweden)
Griet Neukermans
2018-05-01
Full Text Available In this study we develop an analytical model for spectral backscattering and ocean color remote sensing of blooms of the calcifying phytoplankton species Emiliania huxleyi. Blooms of this coccolithophore species are ubiquitous and particularly intense in temperate and subpolar ocean waters. We first present significant improvements to our previous analytical light backscattering model for E. huxleyi coccoliths and coccospheres by accounting for the elliptical shape of coccoliths and the multi-layered coccosphere architecture observed on detailed imagery of E. huxleyi liths and coccospheres. Our new model also includes a size distribution function that closely matches measured E. huxleyi size distributions. The model for spectral backscattering is then implemented in an analytical radiative transfer model to evaluate the variability of spectral remote sensing reflectance with respect to changes in the size distribution of the coccoliths and during a hypothetical E. huxleyi bloom decay event in which coccospheres shed their liths. Our modeled remote sensing reflectance spectra reproduced well the bright milky turquoise coloring of the open ocean typically associated with the final stages of E. huxleyi blooms, with peak reflectance at a wavelength of 0.49 μm. Our results also show that the magnitude of backscattering from coccoliths when attached to or freed from the coccosphere does not differ much, contrary to what is commonly assumed, and that the spectral shape of backscattering is mainly controlled by the size and morphology of the coccoliths, suggesting that they may be estimated from spectral backscattering.
Study on prediction model of irradiation embrittlement for reactor pressure vessel steel
International Nuclear Information System (INIS)
Wang Rongshan; Xu Chaoliang; Huang Ping; Liu Xiangbing; Ren Ai; Chen Jun; Li Chengliang
2014-01-01
The study on prediction model of irradiation embrittlement for reactor pres- sure vessel (RPV) steel is an important method for long term operation. According to the deep analysis of the previous prediction models developed worldwide, the drawbacks of these models were given and a new irradiation embrittlement prediction model PMIE-2012 was developed. A corresponding reliability assessment was carried out by irradiation surveillance data. The assessment results show that the PMIE-2012 have a high reliability and accuracy on irradiation embrittlement prediction. (authors)
Irradiation inhibits vascular anastomotic stenosis in a canine model
International Nuclear Information System (INIS)
Saito, Takeshi; Iguchi, Atsushi; Tabayashi, Koichi
2009-01-01
The graft patency rate after coronary artery bypass grafting (CABG) correlates with anastomotic stenosis. Intracoronary radiation therapy is effective for preventing restenosis after percutaneous coronary intervention (PCI). We postulated that intracoronary radiation therapy could prevent anastomotic stenosis and tested this hypothesis in an animal model. Femoral arteries and veins of beagle dogs were harvested, and composite arterioarterial and arteriovenous grafts were prepared. After external irradiation of the anastomotic sites, these composite grafts were transplanted into femoral arteries. Histomorphometric and immunohistological analyses of the anastomotic sites were performed. The study groups consisted of controls and animals exposed to 10 Gy, 20 Gy, and 30 Gy (n=5, in each group). In the artery graft model, the ratio of negative remodeling was significantly increased in all groups exposed to ≥10 Gy. The ratio of neointimal hyperplasia was significantly decreased in all groups exposed to ≥10 Gy. Cell density of anti-α-actin antibody-positive cells and anti-proliferating cell nuclear antigen (PCNA) antibody-positive cells was highest in the adventitial layer, and the density decreased as the dosage increased. Experimental results were almost the same in the vein graft models as in the artery graft models. With double immunohistostaining, the anti-PCNA antibody-positive cells expressed α-actin. Irradiation can inhibit anastomotic stenosis in a canine model. Adventitia is a factor in the creation of stenosis, and irradiation appears to target the adventitia. We speculate that there might be a possible role for intracoronary irradiation in the future to prevent anastomotic stenosis. (author)
Speech Enhancement by MAP Spectral Amplitude Estimation Using a Super-Gaussian Speech Model
Directory of Open Access Journals (Sweden)
Lotter Thomas
2005-01-01
Full Text Available This contribution presents two spectral amplitude estimators for acoustical background noise suppression based on maximum a posteriori estimation and super-Gaussian statistical modelling of the speech DFT amplitudes. The probability density function of the speech spectral amplitude is modelled with a simple parametric function, which allows a high approximation accuracy for Laplace- or Gamma-distributed real and imaginary parts of the speech DFT coefficients. Also, the statistical model can be adapted to optimally fit the distribution of the speech spectral amplitudes for a specific noise reduction system. Based on the super-Gaussian statistical model, computationally efficient maximum a posteriori speech estimators are derived, which outperform the commonly applied Ephraim-Malah algorithm.
Fu, Yan; Guo, Pei-yuan; Xiang, Ling-zi; Bao, Man; Chen, Xing-hai
2013-08-01
With the gradually mature of hyper spectral image technology, the application of the meat nondestructive detection and recognition has become one of the current research focuses. This paper for the study of marine and freshwater fish by the pre-processing and feature extraction of the collected spectral curve data, combined with BP network structure and LVQ network structure, a predictive model of hyper spectral image data of marine and freshwater fish has been initially established and finally realized the qualitative analysis and identification of marine and freshwater fish quality. The results of this study show that hyper spectral imaging technology combined with the BP and LVQ Artificial Neural Network Model can be used for the identification of marine and freshwater fish detection. Hyper-spectral data acquisition can be carried out without any pretreatment of the samples, thus hyper-spectral imaging technique is the lossless, high- accuracy and rapid detection method for quality of fish. In this study, only 30 samples are used for the exploratory qualitative identification of research, although the ideal study results are achieved, we will further increase the sample capacity to take the analysis of quantitative identification and verify the feasibility of this theory.
The modelling of irradiation embrittlement in submerged-arc welds
International Nuclear Information System (INIS)
Bolton, C.J.; Buswell, J.T.; Jones, R.B.; Moskovic, R.; Priest, R.H.
1996-01-01
Until very recently, the irradiation embrittlement behavior of submerged-arc welds has been interpreted in terms of two mechanisms, namely a matrix damage component and an additional component due to the irradiation-enhanced production of copper-rich precipitates. However, some of the weld specimens from a recent accelerated re-irradiation experiment have shown high Charpy shifts which exceeded the values expected from the measured shift in yield stress. Microstructural examination has revealed the occurrence of intergranular fracture (IGF) in these specimens, accompanied by grain boundary segregation of phosphorus. Theoretical models were developed to predict the parametric dependence of irradiation-enhanced phosphorus segregation on experimental variables. Using these parametric forms, along with the concept of a critical level of segregation for the onset of IGF instead of cleavage, a three mechanism trend curve has been developed. The form of this trend curve, taking into account IGF as well as matrix and copper embrittlement, is thus mechanistically based. The constants in the equation, however, are obtained by a statistical fit to the actual Charpy shift database
The influence of spectral nudging on typhoon formation in regional climate models
Feser, Frauke; Barcikowska, Monika
2012-03-01
Regional climate models can successfully simulate tropical cyclones and typhoons. This has been shown and was evaluated for hindcast studies of the past few decades. But often global and regional weather phenomena are not simulated at the observed location, or occur too often or seldom even though the regional model is driven by global reanalysis data which constitute a near-realistic state of the global atmosphere. Therefore, several techniques have been developed in order to make the regional model follow the global state more closely. One is spectral nudging, which is applied for horizontal wind components with increasing strength for higher model levels in this study. The aim of this study is to show the influence that this method has on the formation of tropical cyclones (TC) in regional climate models. Two ensemble simulations (each with five simulations) were computed for Southeast Asia and the Northwestern Pacific for the typhoon season 2004, one with spectral nudging and one without. First of all, spectral nudging reduced the overall TC number by about a factor of 2. But the number of tracks which are similar to observed best track data (BTD) was greatly increased. Also, spatial track density patterns were found to be more similar when using spectral nudging. The tracks merge after a short time for the spectral nudging simulations and then follow the BTD closely; for the no nudge cases the similarity is greatly reduced. A comparison of seasonal precipitation, geopotential height, and temperature fields at several height levels with observations and reanalysis data showed overall a smaller ensemble spread, higher pattern correlations and reduced root mean square errors and biases for the spectral nudged simulations. Vertical temperature profiles for selected TCs indicate that spectral nudging is not inhibiting TC development at higher levels. Both the Madden-Julian Oscillation and monsoonal precipitation are reproduced realistically by the regional model
The influence of spectral nudging on typhoon formation in regional climate models
International Nuclear Information System (INIS)
Feser, Frauke; Barcikowska, Monika
2012-01-01
Regional climate models can successfully simulate tropical cyclones and typhoons. This has been shown and was evaluated for hindcast studies of the past few decades. But often global and regional weather phenomena are not simulated at the observed location, or occur too often or seldom even though the regional model is driven by global reanalysis data which constitute a near-realistic state of the global atmosphere. Therefore, several techniques have been developed in order to make the regional model follow the global state more closely. One is spectral nudging, which is applied for horizontal wind components with increasing strength for higher model levels in this study. The aim of this study is to show the influence that this method has on the formation of tropical cyclones (TC) in regional climate models. Two ensemble simulations (each with five simulations) were computed for Southeast Asia and the Northwestern Pacific for the typhoon season 2004, one with spectral nudging and one without. First of all, spectral nudging reduced the overall TC number by about a factor of 2. But the number of tracks which are similar to observed best track data (BTD) was greatly increased. Also, spatial track density patterns were found to be more similar when using spectral nudging. The tracks merge after a short time for the spectral nudging simulations and then follow the BTD closely; for the no nudge cases the similarity is greatly reduced. A comparison of seasonal precipitation, geopotential height, and temperature fields at several height levels with observations and reanalysis data showed overall a smaller ensemble spread, higher pattern correlations and reduced root mean square errors and biases for the spectral nudged simulations. Vertical temperature profiles for selected TCs indicate that spectral nudging is not inhibiting TC development at higher levels. Both the Madden–Julian Oscillation and monsoonal precipitation are reproduced realistically by the regional model
A Spectral Geometrical Model for Compton Scatter Tomography Based on the SSS Approximation
DEFF Research Database (Denmark)
Kazantsev, Ivan G.; Olsen, Ulrik Lund; Poulsen, Henning Friis
2016-01-01
The forward model of single scatter in the Positron Emission Tomography for a detector system possessing an excellent spectral resolution under idealized geometrical assumptions is investigated. This model has the form of integral equations describing a flux of photons emanating from the same ann...
Analytical dose modeling for preclinical proton irradiation of millimetric targets.
Vanstalle, Marie; Constanzo, Julie; Karakaya, Yusuf; Finck, Christian; Rousseau, Marc; Brasse, David
2018-01-01
Due to the considerable development of proton radiotherapy, several proton platforms have emerged to irradiate small animals in order to study the biological effectiveness of proton radiation. A dedicated analytical treatment planning tool was developed in this study to accurately calculate the delivered dose given the specific constraints imposed by the small dimensions of the irradiated areas. The treatment planning system (TPS) developed in this study is based on an analytical formulation of the Bragg peak and uses experimental range values of protons. The method was validated after comparison with experimental data from the literature and then compared to Monte Carlo simulations conducted using Geant4. Three examples of treatment planning, performed with phantoms made of water targets and bone-slab insert, were generated with the analytical formulation and Geant4. Each treatment planning was evaluated using dose-volume histograms and gamma index maps. We demonstrate the value of the analytical function for mouse irradiation, which requires a targeting accuracy of 0.1 mm. Using the appropriate database, the analytical modeling limits the errors caused by misestimating the stopping power. For example, 99% of a 1-mm tumor irradiated with a 24-MeV beam receives the prescribed dose. The analytical dose deviations from the prescribed dose remain within the dose tolerances stated by report 62 of the International Commission on Radiation Units and Measurements for all tested configurations. In addition, the gamma index maps show that the highly constrained targeting accuracy of 0.1 mm for mouse irradiation leads to a significant disagreement between Geant4 and the reference. This simulated treatment planning is nevertheless compatible with a targeting accuracy exceeding 0.2 mm, corresponding to rat and rabbit irradiations. Good dose accuracy for millimetric tumors is achieved with the analytical calculation used in this work. These volume sizes are typical in mouse
International Nuclear Information System (INIS)
Ostachowicz, W; Kudela, P
2010-01-01
A Spectral Element Method is used for wave propagation modelling. A 3D solid spectral element is derived with shape functions based on Lagrange interpolation and Gauss-Lobatto-Legendre points. This approach is applied for displacement approximation suited for fundamental modes of Lamb waves as well as potential distribution in piezoelectric transducers. The novelty is the model geometry extension from flat to curved elements for application in shell-like structures. Exemplary visualisations of waves excited by the piezoelectric transducers in curved shell structure made of aluminium alloy are presented. Simple signal analysis of wave interaction with crack is performed. The crack is modelled by separation of appropriate nodes between elements. An investigation of influence of the crack length on wave propagation signals is performed. Additionally, some aspects of the spectral element method implementation are discussed.
Modeling of spectral atmosphere transmission for infrared radiation
International Nuclear Information System (INIS)
Wiecek, B.; Olbrycht, R.
2009-01-01
IR radiation transmission of the atmosphere is an important factor during the thermovision remote sensing and measurement. Transmission coefficient of the atmosphere depends on its content and it is attenuated mainly due to the vapor concentration. Every calibrated thermal camera should be equipped with the digital system which implements the transmission model of the atmosphere. The model presented in this work is based on Beer and Bouguer laws. The proposed simplified model of transmission atmosphere is suitable for implementation in the thermal cameras. A simple digital controller of the camera can calculate the transmission coefficient and correct the temperature measurement. The model takes in account both scattering and absorption due the quantum effects when the photons are interacting with the molecules. (author)
Spectral evaluation of Earth geopotential models and an experiment ...
Indian Academy of Sciences (India)
the models and monitoring the improvements in gravity field recovery are required. This study assesses ... group from the Inter- national Gravity Field Service (IGFS) and the ..... the method, the process may therefore be iter- ated until the ...
Spectral rheology in a sphere. [for geological models
Caputo, M.
1984-01-01
An earth model is considered whose rheology is described by a stress train relation similar to that which seems to fit the laboratory data resulting from constant strain rate and creep experiments on polycrystalline halite and granite. The response of the model to a surface load is studied. It is found that the displacement and the creep are weakly dependent on the wavenumber and that the strain energy is concentrated in the low wavenumber and coherent over large regions.
Wavelet-Based Modelling of Spectral BRDF Data
Claustres , Luc; Boucher , Yannick; Paulin , Mathias
2004-01-01
International audience; The Bidirectional Reflectance Distribution Function (BRDF) is an important surface property, and is commonly used to describe reflected light patterns. However, the BRDF is a complex function since it has four angular degrees of freedom and also depends on the wavelength. The direct use of BRDF data set may be inefficient for scene modelling algorithms for example. Thus, models provide compression and additional functionalities like interpolation. One common way consis...
International Nuclear Information System (INIS)
Gomes, Renato G.; Rebello, Wilson F.; Cavaliere, Marcos Paulo; Vellozo, Sergio O.; Moreira Junior, Luis; Vital, Helio C.; Silva, Ademir X.
2013-01-01
Using the MCNPX code, the objective was to calculate by means of computer simulation spectroscopy range inside the irradiation chamber upper radiator gamma research irradiating facility Army Technology Center (CTEx). The calculations were performed in the spectral range usual 2 points for research purposes irradiating the energy spectra of gamma rays from the source of Cesium chloride 137. Sought the discretization of the spectrum in 100 channels at points of upper bound of 1cm higher and lower dose rates previously known. It was also conducted in the laboratory lifting the spectrum of Cesium-137 source using NaI scintillator detector and multichannel analyzer. With the source spectrum Cesium-137 contained in the literature and raised in the laboratory, both used as reference for comparison and analysis in terms of probability of emission maximum of 0.661 MeV The spectra were quite consistent in terms of the behavior of the energy distributions with scores. The position of maximum dose rate showed absorption detection almost maximum energy of 0.661 MeV photopeak In the spectrum of the position of minimum dosage rate, it was found that due to the removal of the source point of interest, some loss detection were caused by Compton scattering. (author)
Solar surface magnetism and irradiance on time scales
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
Energy Technology Data Exchange (ETDEWEB)
Druce, S.G.; English, C.A.; Foreman, A.J.E.; McElroy, R.J.; Vatter, I.A. [AEA Technology, Didcot (United Kingdom). Harwell Lab.; Bolton, C.J.; Buswell, J.T.; Jones, R.B. [Nuclear Electric, Berkeley (United Kingdom). Berkeley Technology Centre
1996-12-31
Recent results on neutron-irradiated RPV submerged-arc welds have revealed grain boundary segregation of phosphorus during irradiation, which may lead to intergranular fracture. However, the experimental database is insufficient to define the dependence of the process on variables such ad dose, dose-rate and temperature. This paper describes work in which two existing models of phosphorus segregation, under thermal or irradiation conditions, have been developed to obtain predictions of these dependencies. The critical parameters in the models have been adjusted to give consistency with the available reference data, and predictions have been made of the dependence of segregation on a number of variables.
Digitalization of a non-irradiated acute myeloid leukemia model.
Li, Rudong; Cheng, Hui; Cheng, Tao; Liu, Lei
2016-08-26
Computer-aided, interdisciplinary researches for biomedicine have valuable prospects, as digitalization of experimental subjects provide opportunities for saving the economic costs of researches, as well as promoting the acquisition of knowledge. Acute myeloid leukemia (AML) is intensively studied over long periods of time. Till nowaday, most of the studies primarily focus on the leukemic cells rather than how normal hematopoietic cells are affected by the leukemic environment. Accordingly, the conventional animal models for AML are mostly myeloablated as leukemia can be induced with short latency and complete penetrance. Meanwhile, most previous computational models focus on modeling the leukemic cells but not the multi-tissue leukemic body resided by both leukemic and normal blood cells. Recently, a non-irradiated AML mouse model has been established; therefore, normal hematopoietic cells can be investigated during leukemia development. Experiments based on the non-irradiated animal model have monitored the kinetics of leukemic and (intact) hematopoietic cells in multiple tissues simultaneously; and thus a systematic computational model for the multi-tissue hematopoiesis under leukemia has become possible. In the present work, we adopted the modeling methods in previous works, but aimed to model the tri-tissue (peripheral blood, spleen and bone marrow) dynamics of hematopoiesis under leukemia. The cell kinetics generated from the non-irradiated experimental model were used as the reference data for modeling. All mathematical formulas were systematically enumerated, and model parameters were estimated via numerical optimization. Multiple validations by additional experimental data were then conducted for the established computational model. In the results, we illustrated that the important fact of functional depression of hematopoietic stem/progenitor cells (HSC/HPC) in leukemic bone marrow (BM), which must require additional experiments to be established, could
Directory of Open Access Journals (Sweden)
Jinxing Liang
2016-01-01
Full Text Available The construction of spectral discoloration model, based on aging test and simulating degradation experiment, was proposed to detect the aging degree of red lead pigment in ancient murals and to reproduce the spectral data supporting digital restoration of the ancient murals. The degradation process of red lead pigment under the aging test conditions was revealed by X-ray diffraction, scanning electron microscopy, and spectrophotometer. The simulating degradation experiment was carried out by proportionally mixing red lead and lead dioxide with referring to the results of aging test. The experimental result indicated that the pure red lead was gradually turned into black lead dioxide, and the amount of tiny particles of the aging sample increased faced with aging process. Both the chroma and lightness of red lead pigment decreased with discoloration, and its hue essentially remains unchanged. In addition, the spectral reflectance curves of the aging samples almost started rising at about 550 nm with the inflection moving slightly from about 570 nm to 550 nm. The spectral reflectance of samples in long- and in short-wavelength regions was fitted well with the logarithmic and linear function. The spectral discoloration model was established, and the real aging red lead pigment in Dunhuang murals was measured and verified the effectiveness of the model.
Earthquake Source Spectral Study beyond the Omega-Square Model
Uchide, T.; Imanishi, K.
2017-12-01
Earthquake source spectra have been used for characterizing earthquake source processes quantitatively and, at the same time, simply, so that we can analyze the source spectra for many earthquakes, especially for small earthquakes, at once and compare them each other. A standard model for the source spectra is the omega-square model, which has the flat spectrum and the falloff inversely proportional to the square of frequencies at low and high frequencies, respectively, which are bordered by a corner frequency. The corner frequency has often been converted to the stress drop under the assumption of circular crack models. However, recent studies claimed the existence of another corner frequency [Denolle and Shearer, 2016; Uchide and Imanishi, 2016] thanks to the recent development of seismic networks. We have found that many earthquakes in areas other than the area studied by Uchide and Imanishi [2016] also have source spectra deviating from the omega-square model. Another part of the earthquake spectra we now focus on is the falloff rate at high frequencies, which will affect the seismic energy estimation [e.g., Hirano and Yagi, 2017]. In June, 2016, we deployed seven velocity seismometers in the northern Ibaraki prefecture, where the shallow crustal seismicity mainly with normal-faulting events was activated by the 2011 Tohoku-oki earthquake. We have recorded seismograms at 1000 samples per second and at a short distance from the source, so that we can investigate the high-frequency components of the earthquake source spectra. Although we are still in the stage of discovery and confirmation of the deviation from the standard omega-square model, the update of the earthquake source spectrum model will help us systematically extract more information on the earthquake source process.
International Nuclear Information System (INIS)
Greenwood, Charles; Christie, David; Venugopal, Vengatesan; Morrison, James; Vogler, Arne
2016-01-01
This paper presents results from numerical simulations of three Oscillating Wave Surge Converters (OWSC) using two different computational models, Boussinesq wave (BW) and Spectral wave (SW) of the commercial software suite MIKE. The simulation of a shallow water wave farm applies alternative methods for implementing a frequency dependent absorption in both the BW and SW models, where energy extraction is based on experimental data from a scaled Oyster device. The effects of including wave diffraction within the SW model is tested by using diffraction smoothing steps and various directional wave conditions. The results of this study reveal important information on the models realms of validity that is heavily dependent on the incident sea state and the removal of diffraction for the SW model. This yields an increase in simulation accuracy for far-field disturbances when diffraction is entirely removed. This highlights specific conditions where the BW and SW model may thrive but also regions where reduced performance is observed. The results presented in this paper have not been validated with real sea site wave device array performance, however, the methodology described would be useful to device developers to arrive at preliminary decisions on array configurations and to minimise negative environmental impacts.
Polarisation Spectral Synthesis For Type Ia Supernova Explosion Models
Bulla, Mattia
2017-02-01
Despite their relevance across a broad range of astrophysical research topics, Type Ia supernova explosions are still poorly understood and answers to the questions of when, why and how these events are triggered remain unclear. In this respect, polarisation offers a unique opportunity to discriminate between the variety of possible scenarios. The observational evidence that Type Ia supernovae are associated with rather low polarisation signals (smaller than a few per cent) places strong constraints for models and calls for modest asphericities in the progenitor system and/or explosion mechanism.The goal of this thesis is to assess the validity of contemporary Type Ia supernova explosion models by testing whether their predicted polarisation signatures can account for the small signals usually observed. To this end, we have implemented and tested an innovative Monte Carlo scheme in the radiative transfer code artis. Compared to previous Monte Carlo approaches, this technique produces synthetic observables (light curves, flux and polarisation spectra) with a substantial reduction in the Monte Carlo noise and therefore in the required computing time. This improvement is particularly crucial for our study as we aim to extract very weak polarisation signals, comparable to those detected in Type Ia supernovae. We have also demonstrated the applicability of this method to other classes of supernovae via a preliminary study of the first spectropolarimetry observations of superluminous supernovae.Using this scheme, we have calculated synthetic spectropolarimetry for three multi-dimensional explosion models recently proposed as promising candidates to explain Type Ia supernovae. Our findings highlight the power of spectropolarimetry in testing and discriminating between different scenarios. While all the three models predict light curves and flux spectra that are similar to each others and reproduce those observed in Type Ia supernovae comparably well, polarisation does
de la Fuente, Alberto; Meruane, Carolina
2017-09-01
Altiplanic wetlands are unique ecosystems located in the elevated plateaus of Chile, Argentina, Peru, and Bolivia. These ecosystems are under threat due to changes in land use, groundwater extractions, and climate change that will modify the water balance through changes in precipitation and evaporation rates. Long-term prediction of the fate of aquatic ecosystems imposes computational constraints that make finding a solution impossible in some cases. In this article, we present a spectral model for long-term simulations of the thermodynamics of shallow wetlands in the limit case when the water depth tends to zero. This spectral model solves for water and sediment temperature, as well as heat, momentum, and mass exchanged with the atmosphere. The parameters of the model (water depth, thermal properties of the sediments, and surface albedo) and the atmospheric downscaling were calibrated using the MODIS product of the land surface temperature. Moreover, the performance of the daily evaporation rates predicted by the model was evaluated against daily pan evaporation data measured between 1964 and 2012. The spectral model was able to correctly represent both seasonal fluctuation and climatic trends observed in daily evaporation rates. It is concluded that the spectral model presented in this article is a suitable tool for assessing the global climate change effects on shallow wetlands whose thermodynamics is forced by heat exchanges with the atmosphere and modulated by the heat-reservoir role of the sediments.
Nantasenamat, Chanin; Simeon, Saw; Owasirikul, Wiwat; Songtawee, Napat; Lapins, Maris; Prachayasittikul, Virapong; Wikberg, Jarl E S
2014-10-15
Green fluorescent protein (GFP) has immense utility in biomedical imaging owing to its autofluorescent nature. In efforts to broaden the spectral diversity of GFP, there have been several reports of engineered mutants via rational design and random mutagenesis. Understanding the origins of spectral properties of GFP could be achieved by means of investigating its structure-activity relationship. The first quantitative structure-property relationship study for modeling the spectral properties, particularly the excitation and emission maximas, of GFP was previously proposed by us some years ago in which quantum chemical descriptors were used for model development. However, such simplified model does not consider possible effects that neighboring amino acids have on the conjugated π-system of GFP chromophore. This study describes the development of a unified proteochemometric model in which the GFP chromophore and amino acids in its vicinity are both considered in the same model. The predictive performance of the model was verified by internal and external validation as well as Y-scrambling. Our strategy provides a general solution for elucidating the contribution that specific ligand and protein descriptors have on the investigated spectral property, which may be useful in engineering novel GFP variants with desired characteristics. Copyright © 2014 Wiley Periodicals, Inc.
Spectral decomposition of model operators in de Branges spaces
International Nuclear Information System (INIS)
Gubreev, Gennady M; Tarasenko, Anna A
2011-01-01
The paper is devoted to studying a class of completely continuous nonselfadjoint operators in de Branges spaces of entire functions. Among other results, a class of unconditional bases of de Branges spaces consisting of values of their reproducing kernels is constructed. The operators that are studied are model operators in the class of completely continuous non-dissipative operators with two-dimensional imaginary parts. Bibliography: 22 titles.
An object-oriented approach to evaluating multiple spectral models
International Nuclear Information System (INIS)
Majoras, R.E.; Richardson, W.M.; Seymour, R.S.
1995-01-01
A versatile, spectroscopy analysis engine has been developed by using object-oriented design and analysis techniques coupled with an object-oriented language, C++. This engine provides the spectroscopist with the choice of several different peak shape models that are tailored to the type of spectroscopy being performed. It also allows ease of development in adapting the engine to other analytical methods requiring more complex peak fitting in the future. This results in a program that can currently be used across a wide range of spectroscopy applications and anticipates inclusion of future advances in the field. (author) 6 refs.; 1 fig
A three-dimensional spectral element model for the solution of the hydrostatic primitive equations
Iskandarani, M; Levin, J C
2003-01-01
We present a spectral element model to solve the hydrostatic primitive equations governing large-scale geophysical flows. The highlights of this new model include unstructured grids, dual h-p paths to convergence, and good scalability characteristics on present day parallel computers including Beowulf-class systems. The behavior of the model is assessed on three process-oriented test problems involving wave propagation, gravitational adjustment, and nonlinear flow rectification, respectively. The first of these test problems is a study of the convergence properties of the model when simulating the linear propagation of baroclinic Kelvin waves. The second is an intercomparison of spectral element and finite-difference model solutions to the adjustment of a density front in a straight channel. Finally, the third problem considers the comparison of model results to measurements obtained from a laboratory simulation of flow around a submarine canyon. The aforementioned tests demonstrate the good performance of th...
THE IMPACT OF ACCURATE EXTINCTION MEASUREMENTS FOR X-RAY SPECTRAL MODELS
Energy Technology Data Exchange (ETDEWEB)
Smith, Randall K. [Smithsonian Astrophysical Observatory, 60 Garden Street, Cambridge, MA 02138 (United States); Valencic, Lynne A. [NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Corrales, Lia, E-mail: lynne.a.valencic@nasa.gov [MIT Kavli Institute for Astrophysics and Space Research, 77 Massachusetts Avenue, 37-241, Cambridge, MA 02139 (United States)
2016-02-20
Interstellar extinction includes both absorption and scattering of photons from interstellar gas and dust grains, and it has the effect of altering a source's spectrum and its total observed intensity. However, while multiple absorption models exist, there are no useful scattering models in standard X-ray spectrum fitting tools, such as XSPEC. Nonetheless, X-ray halos, created by scattering from dust grains, are detected around even moderately absorbed sources, and the impact on an observed source spectrum can be significant, if modest, compared to direct absorption. By convolving the scattering cross section with dust models, we have created a spectral model as a function of energy, type of dust, and extraction region that can be used with models of direct absorption. This will ensure that the extinction model is consistent and enable direct connections to be made between a source's X-ray spectral fits and its UV/optical extinction.
Firework Model: Time Dependent Spectral Evolution of GRB
Barbiellini, Guido; Longo, Francesco; Ghirlanda, G.; Celotti, A.; Bosnjak, Z.
2004-09-01
The energetics of the long duration GRB phenomenon is compared with models of a rotating BH in a strong magnetic field generated by an accreting torus. The GRB energy emission is attributed to magnetic field vacuum breakdown that gives origin to a e +/- fireball. Its subsequent evolution is hypothesized in analogy with the in-flight decay of an elementary particle. An anisotropy in the fireball propagation is thus naturally produced. The recent discovery in some GRB of an initial phase characterized by a thermal spectrum could be interpreted as the photon emission of the fireball photosphere when it becomes transparent. In particular, the temporal evolution of the emission can be explained as the effect of a radiative deceleration of the out-moving ejecta.
Mathematical models in Slowpoke reactor internal irradiation site
International Nuclear Information System (INIS)
Raza, J.
2007-01-01
The main objective is to build representative mathematical models of neutron activation analysis in a Slowpoke internal irradiation site. Another significant objective is to correct various elements neutron activation analysis measured mass using these models. The neutron flux perturbation is responsible for the measured under-estimation of real masses. We supposed that neutron flux perturbation measurements taken during the Ecole Polytechnique de Montreal Slowpoke reactor first fuel loading were still valid after the second fuelling. .We also supposed that the thermal neutrons spatial and kinetic energies distributions as well as the absorption microscopic cross section dependence on the neutrons kinetic energies were important factors to satisfactorily represent neutron activation analysis results. In addition, we assumed that the neutron flux is isotropic in the laboratory system. We used experimental results from the Slowpoke reactor internal irradiation sites, in order to validate our mathematical models. Our models results are in close agreement with these experimental results..We established an accurate global mathematical correlation of the neutron flux perturbation in function of samples volumes and macroscopic neutron absorption cross sections. It is applicable to sample volumes ranging from 0,1 to 1,3 ml and macroscopic neutron absorption cross section up to 5 moles-b for seven (7) elements with atomic numbers (Z) ranging from 5 to 79. We first came up with a heuristic neutron transport mathematical semi-analytical model, in order to better understand neutrons behaviour in presence of one of several different nuclei samples volumes and mass. In order to well represent the neutron flux perturbation, we combined a neutron transport solution obtained from the spherical harmonics method of a finite cylinder and a mathematical expression combining two cylindrical harmonic functions..With the help of this model and the least squares method, we made extensive
Spectral tensor parameters for wind turbine load modeling from forested and agricultural landscapes
DEFF Research Database (Denmark)
Chougule, Abhijit S.; Mann, Jakob; Segalini, A.
2015-01-01
A velocity spectral tensor model was evaluated from the single-point measurements of wind speed. The model contains three parameters representing the dissipation rate of specific turbulent kinetic energy, a turbulence length scale and the turbulence anisotropy. Sonic anemometer measurements taken...... was better than that of the cross-wind component. No significant difference was found between the performance of the model at the forested and the agricultural areas. © 2014 The Authors. Wind Energy published by John Wiley & Sons, Ltd....
Statistical Clustering and Compositional Modeling of Iapetus VIMS Spectral Data
Pinilla-Alonso, N.; Roush, T. L.; Marzo, G.; Dalle Ore, C. M.; Cruikshank, D. P.
2009-12-01
It has long been known that the surfaces of Saturn's major satellites are predominantly icy objects [e.g. 1 and references therein]. Since 2004, these bodies have been the subject of observations by the Cassini-VIMS (Visual and Infrared Mapping Spectrometer) experiment [2]. Iapetus has the unique property that the hemisphere centered on the apex of its locked synchronous orbital motion around Saturn has a very low geometrical albedo of 2-6%, while the opposite hemisphere is about 10 times more reflective. The nature and origin of the dark material of Iapetus has remained a question since its discovery [3 and references therein]. The nature of this material and how it is distributed on the surface of this body, can shed new light into the knowledge of the Saturnian system. We apply statistical clustering [4] and theoretical modeling [5,6] to address the surface composition of Iapetus. The VIMS data evaluated were obtained during the second flyby of Iapetus, in September 2007. This close approach allowed VIMS to obtain spectra at relatively high spatial resolution, ~1-22 km/pixel. The data we study sampled the trailing hemisphere and part of the dark leading one. The statistical clustering [4] is used to identify statistically distinct spectra on Iapetus. The composition of these distinct spectra are evaluated using theoretical models [5,6]. We thank Allan Meyer for his help. This research was supported by an appointment to the NASA Postdoctoral Program at the Ames Research Center, administered by Oak Ridge Associated Universities through a contract with NASA. [1] A, Coradini et al., 2009, Earth, Moon & Planets, 105, 289-310. [2] Brown et al., 2004, Space Science Reviews, 115, 111-168. [3] Cruikshank, D. et al Icarus, 2008, 193, 334-343. [4] Marzo, G. et al. 2008, Journal of Geophysical Research, 113, E12, CiteID E12009. [5] Hapke, B. 1993, Theory of reflectance and emittance spectroscopy, Cambridge University Press. [6] Shkuratov, Y. et al. 1999, Icarus, 137, 235-246.
Spectrally-consistent regularization modeling of turbulent natural convection flows
International Nuclear Information System (INIS)
Trias, F Xavier; Gorobets, Andrey; Oliva, Assensi; Verstappen, Roel
2012-01-01
The incompressible Navier-Stokes equations constitute an excellent mathematical modelization of turbulence. Unfortunately, attempts at performing direct simulations are limited to relatively low-Reynolds numbers because of the almost numberless small scales produced by the non-linear convective term. Alternatively, a dynamically less complex formulation is proposed here. Namely, regularizations of the Navier-Stokes equations that preserve the symmetry and conservation properties exactly. To do so, both convective and diffusive terms are altered in the same vein. In this way, the convective production of small scales is effectively restrained whereas the modified diffusive term introduces a hyperviscosity effect and consequently enhances the destruction of small scales. In practice, the only additional ingredient is a self-adjoint linear filter whose local filter length is determined from the requirement that vortex-stretching must stop at the smallest grid scale. In the present work, the performance of the above-mentioned recent improvements is assessed through application to turbulent natural convection flows by means of comparison with DNS reference data.
A polychromatic adaption of the Beer-Lambert model for spectral decomposition
Sellerer, Thorsten; Ehn, Sebastian; Mechlem, Korbinian; Pfeiffer, Franz; Herzen, Julia; Noël, Peter B.
2017-03-01
We present a semi-empirical forward-model for spectral photon-counting CT which is fully compatible with state-of-the-art maximum-likelihood estimators (MLE) for basis material line integrals. The model relies on a minimum calibration effort to make the method applicable in routine clinical set-ups with the need for periodic re-calibration. In this work we present an experimental verifcation of our proposed method. The proposed method uses an adapted Beer-Lambert model, describing the energy dependent attenuation of a polychromatic x-ray spectrum using additional exponential terms. In an experimental dual-energy photon-counting CT setup based on a CdTe detector, the model demonstrates an accurate prediction of the registered counts for an attenuated polychromatic spectrum. Thereby deviations between model and measurement data lie within the Poisson statistical limit of the performed acquisitions, providing an effectively unbiased forward-model. The experimental data also shows that the model is capable of handling possible spectral distortions introduced by the photon-counting detector and CdTe sensor. The simplicity and high accuracy of the proposed model provides a viable forward-model for MLE-based spectral decomposition methods without the need of costly and time-consuming characterization of the system response.
Spectral element model for 2-D electrostatic fields in a linear synchronous motor
van Beek, T.A.; Curti, M.; Jansen, J.W.; Gysen, B.L.J.; Paulides, J.J.H.; Lomonova, E.A.
2017-01-01
This paper presents a fast and accurate 2-D spectral element model for analyzing electric field distributions in linear synchronous motors. The electric field distribution is derived using the electric scalar potential for static cases. The spatial potential and electric field distributions obtained
The next step in coastal numerical models: spectral/hp element methods?
DEFF Research Database (Denmark)
Eskilsson, Claes; Engsig-Karup, Allan Peter; Sherwin, Spencer J.
2005-01-01
In this paper we outline the application of spectral/hp element methods for modelling nonlinear and dispersive waves. We present one- and two-dimensional test cases for the shallow water equations and Boussinesqtype equations – including highly dispersive Boussinesq-type equations....
Ching-Teng Lee; Ming-Chin Wu; Shyh-Chin Chen
2005-01-01
The National Centers for Environmental Prediction (NCEP) regional spectral model (RSM) version 97 was used to investigate the regional summertime climate over Taiwan and adjacent areas for June-July-August of 1990 through 2000. The simulated sea-level-pressure and wind fields of RSM1 with 50-km grid space are similar to the reanalysis, but the strength of the...
A new approach to passivity preserving model reduction : the dominant spectral zero method
Ionutiu, R.; Rommes, J.; Antoulas, A.C.; Roos, J.; Costa, L.R.J.
2010-01-01
A new model reduction method for circuit simulation is presented, which preserves passivity by interpolating dominant spectral zeros. These are computed as poles of an associated Hamiltonian system, using an iterative solver: the subspace accelerated dominant pole algorithm (SADPA). Based on a
Spectral scattering is useful for nondestructive sensing of fruit firmness. Prediction models, however, are typically built using multivariate statistical methods such as partial least squares regression (PLSR), whose performance generally depends on the characteristics of the data. The aim of this ...
Regional Spectral Model Workshop in memory of John Roads and Masao Kanamitsu
Hann-Ming Henry Juang; Shyh-Chin Chen; Songyou Hong; Hideki Kanamaru; Thomas Reichler; Takeshi Enomoto; Dian Putrasahan; Bruce T. Anderson; Sasha Gershunov; Haiqin Li; Kei Yoshimura; Nikolaus Buenning; Diane Boomer
2014-01-01
The committee for the 12th International Regional Spectral Model (RSM) Workshop drew its members from the National Centers for Environmental Prediction (NCEP), the U.S. Forest Service, Yonsei University, the Cooperative Institute for Climate and Satellites, the University of Tokyo, the Food and Agriculture Organization of the United Nations (FAO), Hokkaido University,...
Radiative modeling and characterization of aerosol plumes hyper-spectral imagery
International Nuclear Information System (INIS)
Alakian, A.
2008-03-01
This thesis aims at characterizing aerosols from plumes (biomass burning, industrial discharges, etc.) with hyper-spectral imagery. We want to estimate the optical properties of emitted particles and also their micro-physical properties such as number, size distribution and composition. To reach our goal, we have built a forward semi-analytical model, named APOM (Aerosol Plume Optical Model), which allows to simulate the radiative effects of aerosol plumes in the spectral range [0,4-2,5 μm] for nadir viewing sensors. Mathematical formulation and model coefficients are obtained from simulations performed with the radiative transfer code COMANCHE. APOM is assessed on simulated data and proves to be accurate with modeling errors between 1% and 3%. Three retrieval methods using APOM have been developed: L-APOM, M-APOM and A-APOM. These methods take advantage of spectral and spatial dimensions in hyper-spectral images. L-APOM and M-APOM assume a priori knowledge on particles but can estimate their optical and micro-physical properties. Their performances on simulated data are quite promising. A-APOM method does not require any a priori knowledge on particles but only estimates their optical properties. However, it still needs improvements before being usable. On real images, inversion provides satisfactory results for plumes above water but meets some difficulties for plumes above vegetation, which underlines some possibilities of improvement for the retrieval algorithm. (author)
Abdelghany, A M; ElBatal, H A; EzzElDin, F M
2015-10-05
Glasses of lithium fluoroborate of the composition LiF 15%-B2O3 85% with increasing CuO as added dopant were prepared and characterized by combined optical and FTIR spectroscopy before and after gamma irradiation. The optical spectrum of the undoped glass reveals strong UV absorption with two distinct peaks at about 235 and 310 nm and with no visible bands. This strong UV absorption is related to the presence of unavoidable trace iron impurity (Fe(3+)) within the materials used for the preparation of this glass. After irradiation, the spectrum of the undoped glass shows a decrease of the intensity of the UV bands together with the resolution of an induced visible broad band centered at about 520 nm. The CuO doped glasses reveal the same UV absorption beside a very broad visible band centered at 780 nm and this band shows extension and splitting to several component peaks with higher CuO contents. Upon gamma irradiation, the spectra of all CuO-doped glasses reveal pronounced decrease of their intensities. The response of irradiation on the studied glasses is correlated with suggested photochemical reactions together with some shielding effect of the copper ions. The observed visible band is related to the presence of copper as distorted octahedral Cu(2+) ions. Infrared absorption spectra of the prepared glasses show repetitive characteristic triangular and tetrahedral borate units similar to that published from alkali or alkaline earth oxides B2O3 glasses. A suggested formation of (BO3/2F) tetrahedral units is advanced through action of LiF on B2O3 and these suggested units showing the same position and number as BO4 tetrahedra. Copyright © 2015 Elsevier B.V. All rights reserved.
International Nuclear Information System (INIS)
Marušić, Katarina; Pucić, Irina; Desnica, Vladan
2016-01-01
Cultural heritage objects that are radiation treated in order to stop their biodegradation often contain ornamenting materials that cannot be removed. Radiation may produce unwanted changes to such materials. Nacre is a common ornamenting material so this is an attempt to assess the impact of gamma-radiation on its optical properties. Two types of nacre (yellow and white) were obtained from a museum and subjected to different absorbed doses of Co-60 gamma irradiation under the same conditions. The radiation induced changes of nacres color were investigated with fiber optic reflectance spectroscopy (FORS). Colorimetry in CIE Lab space revealed that in both nacres the lightness shifted to darker grey hues at high doses while the color component's (red, green, yellow and blue) behavior depended on the nacre type. Observable changes occurred at doses much above the dose range needed for radiation treatment of cultural heritage objects that are often ornamented with nacre. In UV–vis reflectance spectra of samples irradiated to high doses carbonate radical anion absorption appeared. - Highlights: • Radiation induced changes of nacres color were investigated with FORS. • Nacres darken at high doses while the color component depends on the nacre type. • Observable changes occurred at larger doses than needed for cultural heritage. • For samples irradiated to high doses carbonate radical anion absorption appeared.
Different atmospheric parameters influence on spectral UV radiation (measurements and modelling)
Energy Technology Data Exchange (ETDEWEB)
Chubarova, N Y [Moscow State Univ. (Russian Federation). Meteorological Observatory; Krotkov, N A [Maryland Univ., MD (United States). JCESS/Meteorology Dept.; Geogdzhaev, I V; Bushnev, S V; Kondranin, T V [SUMGF/MIPT, Dolgoprudny (Russian Federation); Khattatov, V U [Central Aerological Observatory, Dolgoprudny (Russian Federation)
1996-12-31
The ultraviolet (UV) radiation plays a vital role in the biophysical processes despite its small portion in the total solar flux. UV radiation is subject to large variations at the Earth surface depending greatly on solar elevation, ozone and cloud amount, aerosols and surface albedo. The analysis of atmospheric parameters influence is based on the spectral archive data of three spectral instruments: NSF spectroradiometer (Barrow network) (NSF Polar Programs UV Spectroradiometer Network 1991-1992,1992), spectrophotometer (SUVS-M) of Central Aerological Observatory CAO, spectroradiometer of Meteorological Observatory of the Moscow State University (MO MSU) and model simulations based on delta-Eddington approximation
Different atmospheric parameters influence on spectral UV radiation (measurements and modelling)
Energy Technology Data Exchange (ETDEWEB)
Chubarova, N.Y. [Moscow State Univ. (Russian Federation). Meteorological Observatory; Krotkov, N.A. [Maryland Univ., MD (United States). JCESS/Meteorology Dept.; Geogdzhaev, I.V.; Bushnev, S.V.; Kondranin, T.V. [SUMGF/MIPT, Dolgoprudny (Russian Federation); Khattatov, V.U. [Central Aerological Observatory, Dolgoprudny (Russian Federation)
1995-12-31
The ultraviolet (UV) radiation plays a vital role in the biophysical processes despite its small portion in the total solar flux. UV radiation is subject to large variations at the Earth surface depending greatly on solar elevation, ozone and cloud amount, aerosols and surface albedo. The analysis of atmospheric parameters influence is based on the spectral archive data of three spectral instruments: NSF spectroradiometer (Barrow network) (NSF Polar Programs UV Spectroradiometer Network 1991-1992,1992), spectrophotometer (SUVS-M) of Central Aerological Observatory CAO, spectroradiometer of Meteorological Observatory of the Moscow State University (MO MSU) and model simulations based on delta-Eddington approximation
Masciotta, Maria-Giovanna; Ramos, Luís F.; Lourenço, Paulo B.; Vasta, Marcello
2017-02-01
Structural monitoring and vibration-based damage identification methods are fundamental tools for condition assessment and early-stage damage identification, especially when dealing with the conservation of historical constructions and the maintenance of strategic civil structures. However, although the substantial advances in the field, several issues must still be addressed to broaden the application range of such tools and to assert their reliability. This study deals with the experimental validation of a novel method for non-destructive damage identification purposes. This method is based on the use of spectral output signals and has been recently validated by the authors through a numerical simulation. After a brief insight into the basic principles of the proposed approach, the spectral-based technique is applied to identify the experimental damage induced on a masonry arch through statically increasing loading. Once the direct and cross spectral density functions of the nodal response processes are estimated, the system's output power spectrum matrix is built and decomposed in eigenvalues and eigenvectors. The present study points out how the extracted spectral eigenparameters contribute to the damage analysis allowing to detect the occurrence of damage and to locate the target points where the cracks appear during the experimental tests. The sensitivity of the spectral formulation to the level of noise in the modal data is investigated and discussed. As a final evaluation criterion, the results from the spectrum-driven method are compared with the ones obtained from existing non-model based damage identification methods.
International Nuclear Information System (INIS)
Silva, M Lino da; Vacher, D; Andre, P; Faure, G; Dudeck, M
2008-01-01
In the first part of this work, described in a previous paper, the thermodynamic conditions in an atmospheric pressure inductively coupled CO 2 -N 2 plasma have been determined, and the radiation emission spectrum has been measured and calibrated in the [250-850 nm] spectral region. In the second part of this work, a synthetic radiation spectrum is obtained taking into account (a) the geometry of the plasma torch and (b) the local thermodynamic conditions of the plasma. This synthetic spectrum has then been compared against the measured spectrum. The good agreement between the two spectra allows validating the spectral database of the line-by-line code SPARTAN for the simulation of the radiative emission of CO 2 -N 2 plasmas from the near-UV to the near-IR spectral region.
Development of a Fast and Accurate PCRTM Radiative Transfer Model in the Solar Spectral Region
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%.
Cessateur, G.; Bolsée, D.; Pereira, N.; Sperfeld, P.; Pape, S.
2017-12-01
The availability of reference spectra for the Solar Spectral Irradiance (SSI) is important for the solar physics, the studies of planetary atmospheres and climatology. The near infrared (NIR) part of these spectra is of great interest for its main role for example, in the Earth's radiative budget. Until recently, some large and unsolved discrepancies (up to 10 %) were observed in the 1.6 μm region between space instruments, models and ground-based measurements. We designed a ground-based instrumentation for SSI measurements at the Top Of Atmosphere (TOA) through atmospheric NIR windows using the Bouguer-Langley technique. The main instrument is a double NIR spectroradiometer designed by Bentham (UK), radiometrically characterized at the Royal Belgian Institute for Space Aeronomy. It was absolute calibrated against a high-temperature blackbody as primary standard for spectral irradiance at the Physikalisch-Technische Bundesanstalt (Germany). The PYR-ILIOS campaign was carried out in June to July 2016 at the Mauna Loa Observatory (Hawaii, USA, 3396 m a.s.l.) follows the four-month IRESPERAD campaign which was carried out in the summer 2011 at the Izaña Atmospheric Observatory (Canary Islands, 2367 m a.s.l.). We present here the results of the 3'week PYR-ILIOS campaign and compare them with the ATLAS 3 spectrum as well as from recently reprocessed NIR solar spectra obtained with SOLAR/SOLSPEC on ISS and SCIAMACHY on ENVISAT. The uncertainty budget of the PYR-ILIOS results will be discussed.
Modeling of MOS radiation and post irradiation effects
International Nuclear Information System (INIS)
Neamen, D.A.
1984-01-01
The radiation response and long term recovery effects in a n-channel MOSFET due to a pulse of ionizing radiation were modeled assuming that electron tunneling from the semiconductor into the oxide and the buildup of interface states were the postirradiation recovery mechanisms. The modeling used convolution theory and took into account the effects of bias changes during the recovery period and charge yield effects. Changing the bias condition during the post-irradiation recovery period changed the recovery rate. The charge yield effects changed the density of trapped positive charge in the oxide but did not change the recovery characteristics for a given oxide thickness. The modeling results were compared to previous experimental results
International Nuclear Information System (INIS)
Jamil, S. S. B.; Ltaif, A. K.; Fadhel, H. M.
2012-12-01
This films of solution grown PbI 2 and of pure material of PbI 2 have been deposited onto glass substrate at 100o C by vacuum thermal evaporation technique. Some physical properties of samples without and with gamma radiation are studied. The irradiation process to the samples were made by applied sample to 1 73 'Cs source with activity 0.635 μci and 6 0C o source with activity 0.62 μci without and with different times of irradiation (3,4,5,6, weeks) to obtain the suitable dose. The x-ray diffraction analysis confirmed that PbI 2 films are polycrystalline, having bollixing structure. Transmission spectra, absorption coefficient and band gap energy are studies were also carried out in the wavelength region of 420-900 nm. The band gap of Pb1 2 at room temperature was found to be 2.37-2.78 eV with direct transition nature using the plots were calculated which were machinating with earlier reported value. The spectral photocurrent of PbI 2 layers deposited in different time were also studied, it is found the maximum photocurrent response always is between the wavelength 490-500 nm. (Author)
AbdelAziz, T D; EzzElDin, F M; El Batal, H A; Abdelghany, A M
2014-10-15
Combined optical and infrared absorption spectra of V2O5-doped cadmium borate glasses were investigated before and after gamma irradiation with a dose of 8 Mrad (=8×10(4) Gy). The undoped base cadmium borate glass reveals a spectrum consisting of strong charge transfer UV absorption bands which are related to the presence of unavoidable contaminated trace iron impurities (mainly Fe(3+)). The V2O5-doped glasses reveal an extra band at 380nm and the high V2O5-content glass also shows a further band at about 420nm. The observed optical spectrum indicates the presence of vanadium ions mainly in the pentavalent state (d(0) configuration). The surplus band at 420nm shows that some trivalent vanadium ions are identified at high V2O5 content. The optical spectra of the glasses after gamma irradiation show small decrease of the intensity of the UV absorption which are interpreted by assuming the transformation of some Fe(3+) ions by photochemical reactions with the presence of high content (45mol%) of heavy massive CdO causing some shielding behavior. FT infrared absorption spectra of the glasses show vibrational bands due to collective presence of triangular and tetrahedral borate groups in their specific wavenumbers. The FTIR spectra are observed to be slightly affected by both the V2O5-dopants being present in modifying low percent or gamma irradiation due to the presence of high content heavy CdO. Copyright © 2014 Elsevier B.V. All rights reserved.
Spectral nudging in regional climate modelling: How strongly should we nudge?
Omrani , Hiba; Drobinski , Philippe; Dubos , Thomas
2012-01-01
International audience; Spectral nudging is a technique consisting in driving regional climate models (RCMs) on selected spatial scales corresponding to those produced by the driving global circulation model (GCM). This technique prevents large and unrealistic departures between the GCM driving fields and the RCM fields at the GCM spatial scales. Theoretically, the relaxation of the RCM towards the GCM should be infinitely strong provided thre are perfect large-scale fields. In practice, the ...
Spectral analysis of surface waves method to assess shear wave velocity within centrifuge models
MURILLO, Carol Andrea; THOREL, Luc; CAICEDO, Bernardo
2009-01-01
The method of the spectral analysis of surface waves (SASW) is tested out on reduced scale centrifuge models, with a specific device, called the mini Falling Weight, developed for this purpose. Tests are performed on layered materials made of a mixture of sand and clay. The shear wave velocity VS determined within the models using the SASW is compared with the laboratory measurements carried out using the bender element test. The results show that the SASW technique applied to centrifuge test...
Directory of Open Access Journals (Sweden)
Mihai V. Putz
2012-11-01
Full Text Available The present work advances the inverse quantum (IQ structural criterion for ordering and characterizing the porosity of the mesosystems based on the recently advanced ratio of the particle-to-wave nature of quantum objects within the extended Heisenberg uncertainty relationship through employing the quantum fluctuation, both for free and observed quantum scattering information, as computed upon spectral identification of the wave-numbers specific to the maximum of absorption intensity record, and to left-, right- and full-width at the half maximum (FWHM of the concerned bands of a given compound. It furnishes the hierarchy for classifying the mesoporous systems from more particle-related (porous, tight or ionic bindings to more wave behavior (free or covalent bindings. This so-called spectral inverse quantum (Spectral-IQ particle-to-wave assignment was illustrated on spectral measurement of FT-IR (bonding bands’ assignment for samples synthesized within different basic environment and different thermal treatment on mesoporous materials obtained by sol-gel technique with n-dodecyl trimethyl ammonium bromide (DTAB and cetyltrimethylammonium bromide (CTAB and of their combination as cosolvents. The results were analyzed in the light of the so-called residual inverse quantum information, accounting for the free binding potency of analyzed samples at drying temperature, and were checked by cross-validation with thermal decomposition techniques by endo-exo thermo correlations at a higher temperature.
Modelling Perception of Structure and Affect in Music: Spectral Centroid and Wishart's Red Bird
Directory of Open Access Journals (Sweden)
Roger T. Dean
2011-12-01
Full Text Available Pearce (2011 provides a positive and interesting response to our article on time series analysis of the influences of acoustic properties on real-time perception of structure and affect in a section of Trevor Wishart’s Red Bird (Dean & Bailes, 2010. We address the following topics raised in the response and our paper. First, we analyse in depth the possible influence of spectral centroid, a timbral feature of the acoustic stream distinct from the high level general parameter we used initially, spectral flatness. We find that spectral centroid, like spectral flatness, is not a powerful predictor of real-time responses, though it does show some features that encourage its continued consideration. Second, we discuss further the issue of studying both individual responses, and as in our paper, group averaged responses. We show that a multivariate Vector Autoregression model handles the grand average series quite similarly to those of individual members of our participant groups, and we analyse this in greater detail with a wide range of approaches in work which is in press and continuing. Lastly, we discuss the nature and intent of computational modelling of cognition using acoustic and music- or information theoretic data streams as predictors, and how the music- or information theoretic approaches may be applied to electroacoustic music, which is ‘sound-based’ rather than note-centred like Western classical music.
Directory of Open Access Journals (Sweden)
Yuanyuan Ma
2016-01-01
Full Text Available To overcome the problem that the horizontal resolution of global climate models may be too low to resolve features which are important at the regional or local scales, dynamical downscaling has been extensively used. However, dynamical downscaling results generally drift away from large-scale driving fields. The nudging technique can be used to balance the performance of dynamical downscaling at large and small scales, but the performances of the two nudging techniques (analysis nudging and spectral nudging are debated. Moreover, dynamical downscaling is now performed at the convection-permitting scale to reduce the parameterization uncertainty and obtain the finer resolution. To compare the performances of the two nudging techniques in this study, three sensitivity experiments (with no nudging, analysis nudging, and spectral nudging covering a period of two months with a grid spacing of 6 km over continental China are conducted to downscale the 1-degree National Centers for Environmental Prediction (NCEP dataset with the Weather Research and Forecasting (WRF model. Compared with observations, the results show that both of the nudging experiments decrease the bias of conventional meteorological elements near the surface and at different heights during the process of dynamical downscaling. However, spectral nudging outperforms analysis nudging for predicting precipitation, and analysis nudging outperforms spectral nudging for the simulation of air humidity and wind speed.
Spectral Cascade-Transport Turbulence Model Development for Two-Phase Flows
Brown, Cameron Scott
Turbulence modeling remains a challenging problem in nuclear reactor applications, particularly for the turbulent multiphase flow conditions in nuclear reactor subchannels. Understanding the fundamental physics of turbulent multiphase flows is crucial for the improvement and further development of multiphase flow models used in reactor operation and safety calculations. Reactor calculations with Reynolds-averaged Navier-Stokes (RANS) approach continue to become viable tools for reactor analysis. The on-going increase in available computational resources allows for turbulence models that are more complex than the traditional two-equation models to become practical choices for nuclear reactor computational fluid dynamic (CFD) and multiphase computational fluid dynamic (M-CFD) simulations. Similarly, increased computational capabilities continue to allow for higher Reynolds numbers and more complex geometries to be evaluated using direct numerical simulation (DNS), thus providing more validation and verification data for turbulence model development. Spectral turbulence models are a promising approach to M-CFD simulations. These models resolve mean flow parameters as well as the turbulent kinetic energy spectrum, reproducing more physical details of the turbulence than traditional two-equation type models. Previously, work performed by other researchers on a spectral cascade-transport model has shown that the model behaves well for single and bubbly twophase decay of isotropic turbulence, single and two-phase uniform shear flow, and single-phase flow in a channel without resolving the near-wall boundary layer for relatively low Reynolds number. Spectral models are great candidates for multiphase RANS modeling since bubble source terms can be modeled as contributions to specific turbulence scales. This work focuses on the improvement and further development of the spectral cascadetransport model (SCTM) to become a three-dimensional (3D) turbulence model for use in M
Spectral properties near the Mott transition in the two-dimensional Hubbard model
Kohno, Masanori
2013-03-01
Single-particle excitations near the Mott transition in the two-dimensional (2D) Hubbard model are investigated by using cluster perturbation theory. The Mott transition is characterized by the loss of the spectral weight from the dispersing mode that leads continuously to the spin-wave excitation of the Mott insulator. The origins of the dominant modes of the 2D Hubbard model near the Mott transition can be traced back to those of the one-dimensional Hubbard model. Various anomalous spectral features observed in cuprate high-temperature superconductors, such as the pseudogap, Fermi arc, flat band, doping-induced states, hole pockets, and spinon-like and holon-like branches, as well as giant kink and waterfall in the dispersion relation, are explained in a unified manner as properties near the Mott transition in a 2D system.
Ultrafast method of calculating the dynamic spectral line shapes for integrated modelling of plasmas
International Nuclear Information System (INIS)
Lisitsa, V.S.
2009-01-01
An ultrafast code for spectral line shape calculations is presented to be used in the integrated modelling of plasmas. The code is based on the close analogy between two mechanisms: (i) Dicke narrowing of the Doppler-broadened spectral lines and (ii) transition from static to impact regime in the Stark broadening. The analogy makes it possible to describe the dynamic Stark broadening in terms of an analytical functional of the static line shape. A comparison of new method with the widely used Frequency Fluctuating Method (FFM) developed by the Marseille University group (B. Talin, R. Stamm, et al.) shows good agreement, with the new method being faster than the standard FFM by nearly two orders of magnitude. The method proposed may significantly simplify the radiation transport modeling and opens new possibilities for integrated modeling of the edge and divertor plasma in tokamaks. (author)
Kosmopoulos, Panagiotis G.; Kazadzis, Stelios; Taylor, Michael; Raptis, Panagiotis I.; Keramitsoglou, Iphigenia; Kiranoudis, Chris; Bais, Alkiviadis F.
2018-02-01
This study focuses on the assessment of surface solar radiation (SSR) based on operational neural network (NN) and multi-regression function (MRF) modelling techniques that produce instantaneous (in less than 1 min) outputs. Using real-time cloud and aerosol optical properties inputs from the Spinning Enhanced Visible and Infrared Imager (SEVIRI) on board the Meteosat Second Generation (MSG) satellite and the Copernicus Atmosphere Monitoring Service (CAMS), respectively, these models are capable of calculating SSR in high resolution (1 nm, 0.05°, 15 min) that can be used for spectrally integrated irradiance maps, databases and various applications related to energy exploitation. The real-time models are validated against ground-based measurements of the Baseline Surface Radiation Network (BSRN) in a temporal range varying from 15 min to monthly means, while a sensitivity analysis of the cloud and aerosol effects on SSR is performed to ensure reliability under different sky and climatological conditions. The simulated outputs, compared to their common training dataset created by the radiative transfer model (RTM) libRadtran, showed median error values in the range -15 to 15 % for the NN that produces spectral irradiances (NNS), 5-6 % underestimation for the integrated NN and close to zero errors for the MRF technique. The verification against BSRN revealed that the real-time calculation uncertainty ranges from -100 to 40 and -20 to 20 W m-2, for the 15 min and monthly mean global horizontal irradiance (GHI) averages, respectively, while the accuracy of the input parameters, in terms of aerosol and cloud optical thickness (AOD and COT), and their impact on GHI, was of the order of 10 % as compared to the ground-based measurements. The proposed system aims to be utilized through studies and real-time applications which are related to solar energy production planning and use.
Let your fingers do the walking: A simple spectral signature model for "remote" fossil prospecting.
Conroy, Glenn C; Emerson, Charles W; Anemone, Robert L; Townsend, K E Beth
2012-07-01
Even with the most meticulous planning, and utilizing the most experienced fossil-hunters, fossil prospecting in remote and/or extensive areas can be time-consuming, expensive, logistically challenging, and often hit or miss. While nothing can predict or guarantee with 100% assurance that fossils will be found in any particular location, any procedures or techniques that might increase the odds of success would be a major benefit to the field. Here we describe, and test, one such technique that we feel has great potential for increasing the probability of finding fossiliferous sediments - a relatively simple spectral signature model using the spatial analysis and image classification functions of ArcGIS(®)10 that creates interactive thematic land cover maps that can be used for "remote" fossil prospecting. Our test case is the extensive Eocene sediments of the Uinta Basin, Utah - a fossil prospecting area encompassing ∼1200 square kilometers. Using Landsat 7 ETM+ satellite imagery, we "trained" the spatial analysis and image classification algorithms using the spectral signatures of known fossil localities discovered in the Uinta Basin prior to 2005 and then created interactive probability models highlighting other regions in the Basin having a high probability of containing fossiliferous sediments based on their spectral signatures. A fortuitous "post-hoc" validation of our model presented itself. Our model identified several paleontological "hotspots", regions that, while not producing any fossil localities prior to 2005, had high probabilities of being fossiliferous based on the similarities of their spectral signatures to those of previously known fossil localities. Subsequent fieldwork found fossils in all the regions predicted by the model. Copyright © 2012 Elsevier Ltd. All rights reserved.
SPECTRAL COLOR INDICES BASED GEOSPATIAL MODELING OF SOIL ORGANIC MATTER IN CHITWAN DISTRICT, NEPAL
Directory of Open Access Journals (Sweden)
U. K. Mandal
2016-06-01
Full Text Available Space Technology provides a resourceful-cost effective means to assess soil nutrients essential for soil management plan. Soil organic matter (SOM is one of valuable controlling productivity of crops by providing nutrient in farming systems. Geospatial modeling of soil organic matter is essential if there is unavailability of soil test laboratories and its strong spatial correlation. In the present analysis, soil organic matter is modeled from satellite image derived spectral color indices. Brightness Index (BI, Coloration Index (CI, Hue Index (HI, Redness Index (RI and Saturation Index (SI were calculated by converting DN value to radiance and radiance to reflectance from Thematic Mapper image. Geospatial model was developed by regressing SOM with color indices and producing multiple regression model using stepwise regression technique. The multiple regression equation between SOM and spectral indices was significant with R = 0. 56 at 95% confidence level. The resulting MLR equation was then used for the spatial prediction for the entire study area. Redness Index was found higher significance in estimating the SOM. It was used to predict SOM as auxiliary variables using cokringing spatial interpolation technique. It was tested in seven VDCs of Chitwan district of Nepal using Thematic Mapper remotely sensed data. SOM was found to be measured ranging from 0.15% to 4.75 %, with a mean of 2.24 %. Remotely sensed data derived spectral color indices have the potential as useful auxiliary variables for estimating SOM content to generate soil fertility management plans.
Asymptotic stability of spectral-based PDF modeling for homogeneous turbulent flows
Campos, Alejandro; Duraisamy, Karthik; Iaccarino, Gianluca
2015-11-01
Engineering models of turbulence, based on one-point statistics, neglect spectral information inherent in a turbulence field. It is well known, however, that the evolution of turbulence is dictated by a complex interplay between the spectral modes of velocity. For example, for homogeneous turbulence, the pressure-rate-of-strain depends on the integrated energy spectrum weighted by components of the wave vectors. The Interacting Particle Representation Model (IPRM) (Kassinos & Reynolds, 1996) and the Velocity/Wave-Vector PDF model (Van Slooten & Pope, 1997) emulate spectral information in an attempt to improve the modeling of turbulence. We investigate the evolution and asymptotic stability of the IPRM using three different approaches. The first approach considers the Lagrangian evolution of individual realizations (idealized as particles) of the stochastic process defined by the IPRM. The second solves Lagrangian evolution equations for clusters of realizations conditional on a given wave vector. The third evolves the solution of the Eulerian conditional PDF corresponding to the aforementioned clusters. This last method avoids issues related to discrete particle noise and slow convergence associated with Lagrangian particle-based simulations.
A sharp interface model for void growth in irradiated materials
Hochrainer, Thomas; El-Azab, Anter
2015-03-01
A thermodynamic formalism for the interaction of point defects with free surfaces in single-component solids has been developed and applied to the problem of void growth by absorption of point defects in irradiated metals. This formalism consists of two parts, a detailed description of the dynamics of defects within the non-equilibrium thermodynamic frame, and the application of the second law of thermodynamics to provide closure relations for all kinetic equations. Enforcing the principle of non-negative entropy production showed that the description of the problem of void evolution under irradiation must include a relationship between the normal fluxes of defects into the void surface and the driving thermodynamic forces for the void surface motion; these thermodynamic forces are identified for both vacancies and interstitials and the relationships between these forces and the normal point defect fluxes are established using the concepts of transition state theory. The latter theory implies that the defect accommodation into the surface is a thermally activated process. Numerical examples are given to illustrate void growth dynamics in this new formalism and to investigate the effect of the surface energy barriers on void growth. Consequences for phase field models of void growth are discussed.
International Nuclear Information System (INIS)
Malone, Emma; Jehl, Markus; Arridge, Simon; Betcke, Timo; Holder, David
2014-01-01
We investigate the application of multifrequency electrical impedance tomography (MFEIT) to imaging the brain in stroke patients. The use of MFEIT could enable early diagnosis and thrombolysis of ischaemic stroke, and therefore improve the outcome of treatment. Recent advances in the imaging methodology suggest that the use of spectral constraints could allow for the reconstruction of a one-shot image. We performed a simulation study to investigate the feasibility of imaging stroke in a head model with realistic conductivities. We introduced increasing levels of modelling errors to test the robustness of the method to the most common sources of artefact. We considered the case of errors in the electrode placement, spectral constraints, and contact impedance. The results indicate that errors in the position and shape of the electrodes can affect image quality, although our imaging method was successful in identifying tissues with sufficiently distinct spectra. (paper)
Irradiation in adulthood as a new model of schizophrenia.
Directory of Open Access Journals (Sweden)
Yasuhide Iwata
Full Text Available BACKGROUND: Epidemiological studies suggest that radiation exposure may be a potential risk factor for schizophrenia in adult humans. Here, we investigated whether adult irradiation in rats caused behavioral abnormalities relevant to schizophrenia. METHODOLOGY/PRINCIPAL FINDINGS: A total dose of 15-Gy irradiation in six fractionations during 3 weeks was exposed to the forebrain including the subventricular zone (SVZ and subgranular zone (SGZ with male rats in the prone position. Behavioral, immunohistochemical, and neurochemical studies were performed three months after fractionated ionizing irradiation. Three months after fractionated ionizing irradiation, the total numbers of BrdU-positive cells in both the SVZ and SGZ zones of irradiated rats were significantly lower than those of control (sham-irradiated rats. Hyperactivity after administration of the dopaminergic agonist methamphetamine, but not the N-methyl-D-aspartate (NMDA receptor antagonist dizocilpine, was significantly enhanced in the irradiated rats although spontaneous locomotion in the irradiated rats was significantly lower than that of controls. Behavioral abnormalities including auditory sensory gating deficits, social interaction deficits, and working memory deficits were observed in the irradiated rats. CONCLUSION/SIGNIFICANCE: The present study suggests that irradiation in adulthood caused behavioral abnormalities relevant to schizophrenia, and that reduction of adult neurogenesis by irradiation may be associated with schizophrenia-like behaviors in rats.
International Nuclear Information System (INIS)
Zwingelstein, Gilles; Thabet, Gabriel.
1977-01-01
Control algorithms for components of nuclear power plants are currently based on external diagnostic methods. Modeling and identification techniques for autoregressive moving average models (ARMA) for stochastic processes are described. The identified models provide a means of estimating the power spectral density with improved accuracy and computer time compared with the classical methods. They are particularly will suited for on-line estimation of the power spectral density. The observable stochastic process y (t) is modeled assuming that it is the output of a linear filter driven by Gaussian while noise w (t). Two identification schemes were tested to find the orders m and n of the ARMA (m,n) models and to estimate the parameters of the recursion equation relating the input and output signals. The first scheme consists in transforming the ARMA model to an autoregressive model. The parameters of this AR model are obtained using least squares estimation techniques. The second scheme consists in finding the parameters of the ARMA by nonlinear programming techniques. The power spectral density of y(t) is instantaneously deduced from these ARMA models [fr
Kulikov, D V; Trushin, Y V; Veber, K V; Khumer, K; Bitner, R; Shternberg, A R
2001-01-01
The physical model of evolution of the oxygen subsystem defects of the ferroelectric PLZT-ceramics by the neutron irradiation and isochrone annealing is proposed. The model accounts for the effect the lanthanum content on the material properties. The changes in the oxygen vacancies concentration, calculated by the proposed model, agree well with the polarization experimental behavior by the irradiated material annealing
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.
Sparse modeling of EELS and EDX spectral imaging data by nonnegative matrix factorization
Energy Technology Data Exchange (ETDEWEB)
Shiga, Motoki, E-mail: shiga_m@gifu-u.ac.jp [Department of Electrical, Electronic and Computer Engineering, Gifu University, 1-1, Yanagido, Gifu 501-1193 (Japan); Tatsumi, Kazuyoshi; Muto, Shunsuke [Advanced Measurement Technology Center, Institute of Materials and Systems for Sustainability, Nagoya University, Chikusa-ku, Nagoya 464-8603 (Japan); Tsuda, Koji [Graduate School of Frontier Sciences, University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa 277-8561 (Japan); Center for Materials Research by Information Integration, National Institute for Materials Science, 1-2-1 Sengen, Tsukuba 305-0047 (Japan); Biotechnology Research Institute for Drug Discovery, National Institute of Advanced Industrial Science and Technology, 2-4-7 Aomi Koto-ku, Tokyo 135-0064 (Japan); Yamamoto, Yuta [High-Voltage Electron Microscope Laboratory, Institute of Materials and Systems for Sustainability, Nagoya University, Chikusa-ku, Nagoya 464-8603 (Japan); Mori, Toshiyuki [Environment and Energy Materials Division, National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044 (Japan); Tanji, Takayoshi [Division of Materials Research, Institute of Materials and Systems for Sustainability, Nagoya University, Chikusa-ku, Nagoya 464-8603 (Japan)
2016-11-15
Advances in scanning transmission electron microscopy (STEM) techniques have enabled us to automatically obtain electron energy-loss (EELS)/energy-dispersive X-ray (EDX) spectral datasets from a specified region of interest (ROI) at an arbitrary step width, called spectral imaging (SI). Instead of manually identifying the potential constituent chemical components from the ROI and determining the chemical state of each spectral component from the SI data stored in a huge three-dimensional matrix, it is more effective and efficient to use a statistical approach for the automatic resolution and extraction of the underlying chemical components. Among many different statistical approaches, we adopt a non-negative matrix factorization (NMF) technique, mainly because of the natural assumption of non-negative values in the spectra and cardinalities of chemical components, which are always positive in actual data. This paper proposes a new NMF model with two penalty terms: (i) an automatic relevance determination (ARD) prior, which optimizes the number of components, and (ii) a soft orthogonal constraint, which clearly resolves each spectrum component. For the factorization, we further propose a fast optimization algorithm based on hierarchical alternating least-squares. Numerical experiments using both phantom and real STEM-EDX/EELS SI datasets demonstrate that the ARD prior successfully identifies the correct number of physically meaningful components. The soft orthogonal constraint is also shown to be effective, particularly for STEM-EELS SI data, where neither the spatial nor spectral entries in the matrices are sparse. - Highlights: • Automatic resolution of chemical components from spectral imaging is considered. • We propose a new non-negative matrix factorization with two new penalties. • The first penalty is sparseness to choose the number of components from data. • Experimental results with real data demonstrate effectiveness of our method.
Improved SAFARI-1 research reactor irradiation position modeling in OSCAR-3 code system
International Nuclear Information System (INIS)
Moloko, L. E.; Belal, M. G. A. H.
2009-01-01
The demand on the availability of irradiation positions in the SAFARI-1 reactor is continuously increasing due to the commercial pressure to produce isotopes more efficiently. This calls for calculational techniques and modeling methods to be improved regularly to optimize irradiation services. The irradiation position models are improved using the OSCAR-3 code system, and results are compared to experimental measurements. It is concluded that the irradiation position models are essential if realistic core follow and reload studies are to be performed and most importantly, for the realization of improved agreement between experimental data and calculated results. (authors)
Energy Technology Data Exchange (ETDEWEB)
Patra, Anirban [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Wen, Wei [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Martinez Saez, Enrique [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Tome, Carlos [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
2016-05-31
This report describes the implementation of a crystal plasticity framework (VPSC) for irradiation hardening and plastic deformation in the finite element code, MOOSE. Constitutive models for irradiation hardening and the crystal plasticity framework are described in a previous report [1]. Here we describe these models briefly and then describe an algorithm for interfacing VPSC with finite elements. Example applications of tensile deformation of a dog bone specimen and a 3D pre-irradiated bar specimen performed using MOOSE are demonstrated.
Uncertainty Model for Total Solar Irradiance Estimation on Australian Rooftops
Al-Saadi, Hassan; Zivanovic, Rastko; Al-Sarawi, Said
2017-11-01
The installations of solar panels on Australian rooftops have been in rise for the last few years, especially in the urban areas. This motivates academic researchers, distribution network operators and engineers to accurately address the level of uncertainty resulting from grid-connected solar panels. The main source of uncertainty is the intermittent nature of radiation, therefore, this paper presents a new model to estimate the total radiation incident on a tilted solar panel. Where a probability distribution factorizes clearness index, the model is driven upon clearness index with special attention being paid for Australia with the utilization of best-fit-correlation for diffuse fraction. The assessment of the model validity is achieved with the adoption of four goodness-of-fit techniques. In addition, the Quasi Monte Carlo and sparse grid methods are used as sampling and uncertainty computation tools, respectively. High resolution data resolution of solar irradiations for Adelaide city were used for this assessment, with an outcome indicating a satisfactory agreement between actual data variation and model.
International Nuclear Information System (INIS)
Heinisch, H.L.
1991-01-01
Comparisons are made of tensile data on specimens of A212B and A302B pressure vessel steels irradiated at low temperatures (40-90degC) and to low doses (<0.1 dpa) with 14 MeV D-T fusion neutrons in the Rotating Target Neutron Source (RTNS-II), with fission reactor neutrons in the Omega West Reactor (OWR) and the Oak Ridge Research Reactor (ORR), and with the highly thermal spectrum at the pressure vessel surveillance positions of the High Flux Isotope Reactor (HFIR). For each neutron spectrum, damage cross sections are determined for several defect production functions derived from atomistic computer simulations of collision cascades. Displacements per atom (dpa) and the numbers of freely migrating defects are tested as damage correlation parameters for the tensile data. The data from RTNS-II, OWR and ORR correlate fairly well when compared on the basis of dpa, but the data from HFIR show only about one sixth as many dpa are needed to produce the same radiation-induced yield stress changes as in the other neutron spectra. In the HFIR surveillance position a significant fraction of the displacements is produced by recoils resulting from thermal neutron captures. Having energies of about 400 eV, these recoils are much more efficient per unit energy at producing freely migrating defects than the high energy recoils responsible for most of the displacements in the other neutron spectra considered. A significantly better correlation of data from HFIR with those from the other spectra is achieved when the property changes are compared on the basis of the production of freely migrating self-interstitial defects. (orig./MM)
Sampaio, Luis Rafael L; Borges, Lucas T N; Silva, Joyse M F; de Andrade, Francisca Roselin O; Barbosa, Talita M; Oliveira, Tatiana Q; Macedo, Danielle; Lima, Ricardo F; Dantas, Leonardo P; Patrocinio, Manoel Cláudio A; do Vale, Otoni C; Vasconcelos, Silvânia M M
2018-02-01
The use of ketamine (Ket) as a pharmacological model of schizophrenia is an important tool for understanding the main mechanisms of glutamatergic regulated neural oscillations. Thus, the aim of the current study was to evaluate Ket-induced changes in the average spectral power using the hippocampal quantitative electroencephalography (QEEG). To this end, male Wistar rats were submitted to a stereotactic surgery for the implantation of an electrode in the right hippocampus. After three days, the animals were divided into four groups that were treated for 10 consecutive days with Ket (10, 50, or 100 mg/kg). Brainwaves were captured on the 1st or 10th day, respectively, to acute or repeated treatments. The administration of Ket (10, 50, or 100 mg/kg), compared with controls, induced changes in the hippocampal average spectral power of delta, theta, alpha, gamma low or high waves, after acute or repeated treatments. Therefore, based on the alterations in the average spectral power of hippocampal waves induced by Ket, our findings might provide a basis for the use of hippocampal QEEG in animal models of schizophrenia. © 2017 Société Française de Pharmacologie et de Thérapeutique.
Solution to the spectral filter problem of residual terrain modelling (RTM)
Rexer, Moritz; Hirt, Christian; Bucha, Blažej; Holmes, Simon
2018-06-01
In physical geodesy, the residual terrain modelling (RTM) technique is frequently used for high-frequency gravity forward modelling. In the RTM technique, a detailed elevation model is high-pass-filtered in the topography domain, which is not equivalent to filtering in the gravity domain. This in-equivalence, denoted as spectral filter problem of the RTM technique, gives rise to two imperfections (errors). The first imperfection is unwanted low-frequency (LF) gravity signals, and the second imperfection is missing high-frequency (HF) signals in the forward-modelled RTM gravity signal. This paper presents new solutions to the RTM spectral filter problem. Our solutions are based on explicit modelling of the two imperfections via corrections. The HF correction is computed using spectral domain gravity forward modelling that delivers the HF gravity signal generated by the long-wavelength RTM reference topography. The LF correction is obtained from pre-computed global RTM gravity grids that are low-pass-filtered using surface or solid spherical harmonics. A numerical case study reveals maximum absolute signal strengths of ˜ 44 mGal (0.5 mGal RMS) for the HF correction and ˜ 33 mGal (0.6 mGal RMS) for the LF correction w.r.t. a degree-2160 reference topography within the data coverage of the SRTM topography model (56°S ≤ φ ≤ 60°N). Application of the LF and HF corrections to pre-computed global gravity models (here the GGMplus gravity maps) demonstrates the efficiency of the new corrections over topographically rugged terrain. Over Switzerland, consideration of the HF and LF corrections reduced the RMS of the residuals between GGMplus and ground-truth gravity from 4.41 to 3.27 mGal, which translates into ˜ 26% improvement. Over a second test area (Canada), our corrections reduced the RMS of the residuals between GGMplus and ground-truth gravity from 5.65 to 5.30 mGal (˜ 6% improvement). Particularly over Switzerland, geophysical signals (associated, e.g. with
Forecast Method of Solar Irradiance with Just-In-Time Modeling
Suzuki, Takanobu; Goto, Yusuke; Terazono, Takahiro; Wakao, Shinji; Oozeki, Takashi
PV power output mainly depends on the solar irradiance which is affected by various meteorological factors. So, it is required to predict solar irradiance in the future for the efficient operation of PV systems. In this paper, we develop a novel approach for solar irradiance forecast, in which we introduce to combine the black-box model (JIT Modeling) with the physical model (GPV data). We investigate the predictive accuracy of solar irradiance over wide controlled-area of each electric power company by utilizing the measured data on the 44 observation points throughout Japan offered by JMA and the 64 points around Kanto by NEDO. Finally, we propose the application forecast method of solar irradiance to the point which is difficulty in compiling the database. And we consider the influence of different GPV default time on solar irradiance prediction.
Fan, X.; Chen, L.; Ma, Z.
2010-12-01
Climate downscaling has been an active research and application area in the past several decades focusing on regional climate studies. Dynamical downscaling, in addition to statistical methods, has been widely used in downscaling as the advanced modern numerical weather and regional climate models emerge. The utilization of numerical models enables that a full set of climate variables are generated in the process of downscaling, which are dynamically consistent due to the constraints of physical laws. While we are generating high resolution regional climate, the large scale climate patterns should be retained. To serve this purpose, nudging techniques, including grid analysis nudging and spectral nudging, have been used in different models. There are studies demonstrating the benefit and advantages of each nudging technique; however, the results are sensitive to many factors such as nudging coefficients and the amount of information to nudge to, and thus the conclusions are controversy. While in a companion work of developing approaches for quantitative assessment of the downscaled climate, in this study, the two nudging techniques are under extensive experiments in the Weather Research and Forecasting (WRF) model. Using the same model provides fair comparability. Applying the quantitative assessments provides objectiveness of comparison. Three types of downscaling experiments were performed for one month of choice. The first type is serving as a base whereas the large scale information is communicated through lateral boundary conditions only; the second is using the grid analysis nudging; and the third is using spectral nudging. Emphases are given to the experiments of different nudging coefficients and nudging to different variables in the grid analysis nudging; while in spectral nudging, we focus on testing the nudging coefficients, different wave numbers on different model levels to nudge.
Energy Technology Data Exchange (ETDEWEB)
Lozes, G. [CEA Saclay, Dir. de l' Energie Nucleaire (DEN/DSOE), 91 - Gif sur Yvette (France)
2007-07-01
The CPR ISMIR is a CEA-CNRS program on the behaviour of materials submitted to irradiation; it has been begun to support the applied current research programs on the aging of nuclear fuels, the storage and incineration matrices and the future reactors. Its aim is to contribute to scientifically set up the methods for anticipating the behaviour of ceramic materials under irradiation in using the important development of calculation means. Thus have been developed the basic knowledge and the interactions physics and calculation models at pertinent scales have been elaborated. (O.M.)
Spectral flow as a map between N=(2,0)-models
International Nuclear Information System (INIS)
Athanasopoulos, P.; Faraggi, A.E.; Gepner, D.
2014-01-01
The space of (2,0) models is of particular interest among all heterotic-string models because it includes the models with the minimal SO(10) unification structure, which is well motivated by the Standard Model of particle physics data. The fermionic Z 2 ×Z 2 heterotic-string models revealed the existence of a new symmetry in the space of string configurations under the exchange of spinors and vectors of the SO(10) GUT group, dubbed spinor–vector duality. In this paper we generalize this idea to arbitrary internal rational conformal field theories (RCFTs). We explain how the spectral flow operator normally acting within a general (2,2) theory can be used as a map between (2,0) models. We describe the details, give an example and propose more simple currents that can be used in a similar way
Determination of the spectral behaviour of atmospheric soot using different particle models
Skorupski, Krzysztof
2017-08-01
In the atmosphere, black carbon aggregates interact with both organic and inorganic matter. In many studies they are modeled using different, less complex, geometries. However, some common simplification might lead to many inaccuracies in the following light scattering simulations. The goal of this study was to compare the spectral behavior of different, commonly used soot particle models. For light scattering simulations, in the visible spectrum, the ADDA algorithm was used. The results prove that the relative extinction error δCext, in some cases, can be unexpectedly large. Therefore, before starting excessive simulations, it is important to know what error might occur.
Spectral analysis of surface waves method to assess shear wave velocity within centrifuge models
Murillo, Carol Andrea; Thorel, Luc; Caicedo, Bernardo
2009-06-01
The method of the spectral analysis of surface waves (SASW) is tested out on reduced scale centrifuge models, with a specific device, called the mini Falling Weight, developed for this purpose. Tests are performed on layered materials made of a mixture of sand and clay. The shear wave velocity VS determined within the models using the SASW is compared with the laboratory measurements carried out using the bender element test. The results show that the SASW technique applied to centrifuge testing is a relevant method to characterize VS near the surface.
Boore, David M.; Di Alessandro, Carola; Abrahamson, Norman A.
2014-01-01
The stochastic method of simulating ground motions requires the specification of the shape and scaling with magnitude of the source spectrum. The spectral models commonly used are either single-corner-frequency or double-corner-frequency models, but the latter have no flexibility to vary the high-frequency spectral levels for a specified seismic moment. Two generalized double-corner-frequency ω2 source spectral models are introduced, one in which two spectra are multiplied together, and another where they are added. Both models have a low-frequency dependence controlled by the seismic moment, and a high-frequency spectral level controlled by the seismic moment and a stress parameter. A wide range of spectral shapes can be obtained from these generalized spectral models, which makes them suitable for inversions of data to obtain spectral models that can be used in ground-motion simulations in situations where adequate data are not available for purely empirical determinations of ground motions, as in stable continental regions. As an example of the use of the generalized source spectral models, data from up to 40 stations from seven events, plus response spectra at two distances and two magnitudes from recent ground-motion prediction equations, were inverted to obtain the parameters controlling the spectral shapes, as well as a finite-fault factor that is used in point-source, stochastic-method simulations of ground motion. The fits to the data are comparable to or even better than those from finite-fault simulations, even for sites close to large earthquakes.
Energy Technology Data Exchange (ETDEWEB)
Wakai, E.; Hashimoto, N.; Gibson, L.T. [Oak Ridge National Lab., TN (United States)] [and others
1997-08-01
The microstructural evolution of austenitic JPCA aged and solution annealed JPCA, 316R, C, K, and HP steels irradiated at 400{degrees}C in spectrally tailored experiments of the ORR and HFIR has been investigated. The helium generation rates were about 12-16 appm He/dpa on the average up to 17.3 dpa. The number densities and average diameters of dislocation loops in the steels have ranges of 3.3 x 10{sup 21} m{sup -3} and 15.2-26.3 nm, respectively, except for HP steel for which they are 1.1 x 10{sup 23} m{sup -3} and 8.0 nm. Precipitates are formed in all steels except for HP steel, and the number densities and average diameters have ranges of 5.2 x 10{sup 20} - 7.7 x 10{sup 21} m{sup -3} and 3.4- 19.3 nm, respectively. In the 216R, C, and K steels, the precipitates are also formed at grain boundaries, and the mean sizes of these are about 110, 50, and 50 nm, respectively. The number densities of cavities are about 1 x 10{sup 22} m{sup -3} in all the steels. The swelling is low in the steels which form the precipitates.
Soot and Spectral Radiation Modeling for a High-Pressure Turbulent Spray Flame
Energy Technology Data Exchange (ETDEWEB)
Ferreryo-Fernandez, Sebastian [Pennsylvania State Univ., University Park, PA (United States); Paul, Chandan [Pennsylvania State Univ., University Park, PA (United States); Sircar, Arpan [Pennsylvania State Univ., University Park, PA (United States); Imren, Abdurrahman [Pennsylvania State Univ., University Park, PA (United States); Haworth, Daniel C [Pennsylvania State Univ., University Park, PA (United States); Roy, Somesh P [Marquette University (United States); Modest, Michael F [University of California Merced (United States)
2017-04-26
Simulations are performed of a transient high-pressure turbulent n-dodecane spray flame under engine-relevant conditions. An unsteady RANS formulation is used, with detailed chemistry, a semi-empirical two-equation soot model, and a particle-based transported composition probability density function (PDF) method to account for unresolved turbulent fluctuations in composition and temperature. Results from the PDF model are compared with those from a locally well-stirred reactor (WSR) model to quantify the effects of turbulence-chemistry-soot interactions. Computed liquid and vapor penetration versus time, ignition delay, and flame lift-off height are in good agreement with experiment, and relatively small differences are seen between the WSR and PDF models for these global quantities. Computed soot levels and spatial soot distributions from the WSR and PDF models show large differences, with PDF results being in better agreement with experimental measurements. An uncoupled photon Monte Carlo method with line-by-line spectral resolution is used to compute the spectral intensity distribution of the radiation leaving the flame. This provides new insight into the relative importance of molecular gas radiation versus soot radiation, and the importance of turbulent fluctuations on radiative heat transfer.
Modelling 1-minute directional observations of the global irradiance.
Thejll, Peter; Pagh Nielsen, Kristian; Andersen, Elsa; Furbo, Simon
2016-04-01
Direct and diffuse irradiances from the sky has been collected at 1-minute intervals for about a year from the experimental station at the Technical University of Denmark for the IEA project "Solar Resource Assessment and Forecasting". These data were gathered by pyrheliometers tracking the Sun, as well as with apertured pyranometers gathering 1/8th and 1/16th of the light from the sky in 45 degree azimuthal ranges pointed around the compass. The data are gathered in order to develop detailed models of the potentially available solar energy and its variations at high temporal resolution in order to gain a more detailed understanding of the solar resource. This is important for a better understanding of the sub-grid scale cloud variation that cannot be resolved with climate and weather models. It is also important for optimizing the operation of active solar energy systems such as photovoltaic plants and thermal solar collector arrays, and for passive solar energy and lighting to buildings. We present regression-based modelling of the observed data, and focus, here, on the statistical properties of the model fits. Using models based on the one hand on what is found in the literature and on physical expectations, and on the other hand on purely statistical models, we find solutions that can explain up to 90% of the variance in global radiation. The models leaning on physical insights include terms for the direct solar radiation, a term for the circum-solar radiation, a diffuse term and a term for the horizon brightening/darkening. The purely statistical model is found using data- and formula-validation approaches picking model expressions from a general catalogue of possible formulae. The method allows nesting of expressions, and the results found are dependent on and heavily constrained by the cross-validation carried out on statistically independent testing and training data-sets. Slightly better fits -- in terms of variance explained -- is found using the purely
Jafari, Azadeh; Deville, Michel O.; Fiétier, Nicolas
2008-09-01
This study discusses the capability of the constitutive laws for the matrix logarithm of the conformation tensor (LCT model) within the framework of the spectral elements method. The high Weissenberg number problems (HWNP) usually produce a lack of convergence of the numerical algorithms. Even though the question whether the HWNP is a purely numerical problem or rather a breakdown of the constitutive law of the model has remained somewhat of a mystery, it has been recognized that the selection of an appropriate constitutive equation constitutes a very crucial step although implementing a suitable numerical technique is still important for successful discrete modeling of non-Newtonian flows. The LCT model formulation of the viscoelastic equations originally suggested by Fattal and Kupferman is applied for 2-dimensional (2D) FENE-CR model. The Planar Poiseuille flow is considered as a benchmark problem to test this representation at high Weissenberg number. The numerical results are compared with numerical solution of the standard constitutive equation.
Talko, V V; Loganovsky, K M; Drozd, I P; Tukalenko, Ye V; Loganovska, T K; Nechayev, S Yu; Masiuk, S V; Prokhorova, Ye M
2017-12-01
Human brain in prenatal period is a most vulnerable to ionizing radiation body structure. Unlike atomic bombings or radiological interventions in healthcare leading at most to external irradiation the intensive internal exposure may occur upon nuclear reactor accidents followed by substantial release and fallout of radioactive 131I. The latter can lead to specific neuroradioembryological effects. To create an experimental model of prenatal cerebral radiation effects of 131I in human and to determine the experimental and clinical neuroradioembryological effects.Study object. The neuroradioembryological effects in Vistar rats exposed to 131I in prenatal period. Nervous system status and mental status in 104 persons exposed to ionizing radiation in utero due to the ChNPP accident and the same in 78 not exposed subjects. Experimental i.e. behavioral techniques, including the spontaneous locomotive, exploratory activity and learning ability assessment, clinical i.e. neuropsychiatric, neuro and psychometric, neuropsychological, neurophys iological methods, both with dosimetric and statistical methods were applied. Intrauterine irradiation of Wistar rats by 131I was simulated on a model of one time oral 27.5 kBq radionu clide administration in the mid gestation period (0.72±0.14 Gy fetal thyroid dose), which provides extrapolation of neuroradioembryological effects in rats to that in humans exposed to intrauterine radiation as a result of the Chornobyl catastrophe. Abnormalities in behavioral reactions and decreased output of conditioned reflex reactions identified in the 10 month old rats suggest a deterioration of cerebral cognition in exposed animals. Specific cog nitive deficit featuring a disharmonic intellectual development through the relatively decreased verbal intelligence versus relative increase of nonverbal one is remained in prenatally exposed persons. This can indicate to dysfunc tion of cortical limbic system with especial involvement of a dominant
Temporal Evolution of Ion Spectral Structures During a Geomagnetic Storm: Observations and Modeling
Ferradas, C. P.; Zhang, J.-C.; Spence, H. E.; Kistler, L. M.; Larsen, B. A.; Reeves, G. D.; Skoug, R. M.; Funsten, H. O.
2018-01-01
Using the Van Allen Probes/Helium, Oxygen, Proton, and Electron mass spectrometer, we perform a case study of the temporal evolution of ion spectral structures observed in the energy range of 1 to 50 keV throughout the geomagnetic storm of 2 October 2013. The ion spectral features are observed near the inner edge of the plasma sheet and are signatures of fresh transport from the plasma sheet into the inner magnetosphere. We find that the characteristics of the ion structures are determined by the intensity of the convection electric field. Prior to the beginning of the storm, the plasma sheet inner edge exhibits narrow nose spectral structures that vary little in energy across L values. Ion access to the inner magnetosphere during these times is limited to the nose energy bands. As convection is enhanced and large amounts of plasma are injected from the plasma sheet during the main phase of the storm, ion access occurs at a wide energy range, as no nose structures are observed. As the magnetosphere recovers from the storm, single noses and then multiple noses are observed once again. We use a model of ion drift and losses due to charge exchange to simulate the ion spectra and gain insight into the main observed features.
Modeling the irradiance dependency of the quantum efficiency of potosynthesis
Silsbe, G.M.; Kromkamp, J.C.
2012-01-01
Measures of the quantum efficiency of photosynthesis (phi(PSII)) across an irradiance (E) gradient are an increasingly common physiological assay and alternative to traditional photosynthetic-irradiance (PE) assays. Routinely, the analysis and interpretation of these data are analogous to PE
Synthetic spectral analysis of a kinetic model for slow-magnetosonic waves in solar corona
Energy Technology Data Exchange (ETDEWEB)
Ruan, Wenzhi; He, Jiansen; Tu, Chuanyi; Wang, Linghua [School of Earth and Space Sciences, Peking University, Beijing, 100871, China, E-mail: jshept@gmail.com (China); Zhang, Lei [State Key Laboratory of Space Weather, Chinese Academy of Sciences, Beijing 100190 (China); Vocks, Christian [Leibniz-Institut für Astrophysik Potsdam, 14482, Potsdam (Germany); Marsch, Eckart [Institute for Experimental and Applied Physics, Christian-Albrechts-Universität zu Kiel, 24118 Kiel (Germany); Peter, Hardi [Max Plank Institut für Sonnensystemforschung, Justus-von-Liebig-Weg 3, 37077 Göttingen (Germany)
2016-03-25
We propose a kinetic model of slow-magnetosonic waves to explain various observational features associated with the propagating intensity disturbances (PIDs) occurring in the solar corona. The characteristics of slow mode waves, e.g, inphase oscillations of density, velocity, and thermal speed, are reproduced in this kinetic model. Moreover, the red-blue (R-B) asymmetry of the velocity distribution as self-consistently generated in the model is found to be contributed from the beam component, as a result of the competition between Landau resonance and Coulomb collisions. Furthermore, we synthesize the spectral lines and make the spectral analysis, based on the kinetic simulation data of the flux tube plasmas and the hypothesis of the surrounding background plasmas. It is found that the fluctuations of parameters of the synthetic spectral lines are basically consistent with the observations: (1) the line intensity, Doppler shift, and line width are fluctuating in phase; (2) the R-B asymmetry usually oscillate out of phase with the former three parameters; (3) the blueward asymmetry is more evident than the redward asymmetry in the R-B fluctuations. The oscillations of line parameters become weakened for the case with denser surrounding background plasmas. Similar to the observations, there is no doubled-frequency oscillation of the line width for the case with flux-tube plasmas flowing bulkly upward among the static background plasmas. Therefore, we suggest that the “wave + beam flow” kinetic model may be a viable interpretation for the PIDs observed in the solar corona.
Spectral nudging – a scale-selective interior constraint technique – is commonly used in regional climate models to maintain consistency with large-scale forcing while permitting mesoscale features to develop in the downscaled simulations. Several studies have demonst...
MODELLING OF CARBON MONOXIDE AIR POLLUTION IN LARG CITIES BY EVALUETION OF SPECTRAL LANDSAT8 IMAGES
Directory of Open Access Journals (Sweden)
M. Hamzelo
2015-12-01
Full Text Available Air pollution in large cities is one of the major problems that resolve and reduce it need multiple applications and environmental management. Of The main sources of this pollution is industrial activities, urban and transport that enter large amounts of contaminants into the air and reduces its quality. With Variety of pollutants and high volume manufacturing, local distribution of manufacturing centers, Testing and measuring emissions is difficult. Substances such as carbon monoxide, sulfur dioxide, and unburned hydrocarbons and lead compounds are substances that cause air pollution and carbon monoxide is most important. Today, data exchange systems, processing, analysis and modeling is of important pillars of management system and air quality control. In this study, using the spectral signature of carbon monoxide gas as the most efficient gas pollution LANDSAT8 images in order that have better spatial resolution than appropriate spectral bands and weather meters،SAM classification algorithm and Geographic Information System (GIS , spatial distribution of carbon monoxide gas in Tehran over a period of one year from the beginning of 2014 until the beginning of 2015 at 11 map have modeled and then to the model valuation ،created maps were compared with the map provided by the Tehran quality comparison air company. Compare involved plans did with the error matrix and results in 4 types of care; overall, producer, user and kappa coefficient was investigated. Results of average accuracy were about than 80%, which indicates the fit method and data used for modeling.
A new Bayesian model applied to cytogenetic partial body irradiation estimation
International Nuclear Information System (INIS)
Higueras, Manuel; Puig, Pedro; Ainsbury, Elizabeth A.; Vinnikov, Volodymyr A.; Rothkamm, Kai
2016-01-01
A new zero-inflated Poisson model is introduced for the estimation of partial body irradiation dose and fraction of body irradiated. The Bayes factors are introduced as tools to help determine whether a data set of chromosomal aberrations obtained from a blood sample reflects partial or whole body irradiation. Two examples of simulated cytogenetic radiation exposure data are presented to demonstrate the usefulness of this methodology in cytogenetic biological dosimetry. (authors)
Grubbs, Guy; Michell, Robert; Samara, Marilia; Hampton, Donald; Hecht, James; Solomon, Stanley; Jahn, Jorg-Micha
2018-01-01
It is important to routinely examine and update models used to predict auroral emissions resulting from precipitating electrons in Earth's magnetotail. These models are commonly used to invert spectral auroral ground-based images to infer characteristics about incident electron populations when in situ measurements are unavailable. In this work, we examine and compare auroral emission intensities predicted by three commonly used electron transport models using varying electron population characteristics. We then compare model predictions to same-volume in situ electron measurements and ground-based imaging to qualitatively examine modeling prediction error. Initial comparisons showed differences in predictions by the GLobal airglOW (GLOW) model and the other transport models examined. Chemical reaction rates and radiative rates in GLOW were updated using recent publications, and predictions showed better agreement with the other models and the same-volume data, stressing that these rates are important to consider when modeling auroral processes. Predictions by each model exhibit similar behavior for varying atmospheric constants, energies, and energy fluxes. Same-volume electron data and images are highly correlated with predictions by each model, showing that these models can be used to accurately derive electron characteristics and ionospheric parameters based solely on multispectral optical imaging data.
Modeling of helium bubble nucleation and growth in neutron irradiated boron doped RAFM steels
International Nuclear Information System (INIS)
Dethloff, Christian; Gaganidze, Ermile; Svetukhin, Vyacheslav V.; Aktaa, Jarir
2012-01-01
Reduced activation ferritic/martensitic (RAFM) steels are promising candidates for structural materials in future fusion technology. In addition to other irradiation defects, the transmuted helium is believed to strongly influence material hardening and embrittlement behavior. A phenomenological model based on kinetic rate equations is developed to describe homogeneous nucleation and growth of helium bubbles in neutron irradiated RAFM steels. The model is adapted to different 10 B doped EUROFER97 based heats, which already had been studied in past irradiation experiments. Simulations yield bubble size distributions, whereby effects of helium generation rate, surface energy, helium sinks and helium density are investigated. Peak bubble diameters under different conditions are compared to preliminary microstructural results on irradiated specimens. Helium induced hardening was calculated by applying the Dispersed Barrier Hardening model to simulated cluster size distributions. Quantitative microstructural investigations of unirradiated and irradiated specimens will be used to support and verify the model.
Modeling of helium bubble nucleation and growth in neutron irradiated boron doped RAFM steels
Energy Technology Data Exchange (ETDEWEB)
Dethloff, Christian, E-mail: christian.dethloff@kit.edu [Karlsruhe Institute of Technology (KIT), Institute for Applied Materials, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen (Germany); Gaganidze, Ermile [Karlsruhe Institute of Technology (KIT), Institute for Applied Materials, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen (Germany); Svetukhin, Vyacheslav V. [Ulyanovsk State University, Leo Tolstoy Str. 42, 432970 Ulyanovsk (Russian Federation); Aktaa, Jarir [Karlsruhe Institute of Technology (KIT), Institute for Applied Materials, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen (Germany)
2012-07-15
Reduced activation ferritic/martensitic (RAFM) steels are promising candidates for structural materials in future fusion technology. In addition to other irradiation defects, the transmuted helium is believed to strongly influence material hardening and embrittlement behavior. A phenomenological model based on kinetic rate equations is developed to describe homogeneous nucleation and growth of helium bubbles in neutron irradiated RAFM steels. The model is adapted to different {sup 10}B doped EUROFER97 based heats, which already had been studied in past irradiation experiments. Simulations yield bubble size distributions, whereby effects of helium generation rate, surface energy, helium sinks and helium density are investigated. Peak bubble diameters under different conditions are compared to preliminary microstructural results on irradiated specimens. Helium induced hardening was calculated by applying the Dispersed Barrier Hardening model to simulated cluster size distributions. Quantitative microstructural investigations of unirradiated and irradiated specimens will be used to support and verify the model.
Galliano, Frédéric
2018-05-01
This article presents a new dust spectral energy distribution (SED) model, named HerBIE, aimed at eliminating the noise-induced correlations and large scatter obtained when performing least-squares fits. The originality of this code is to apply the hierarchical Bayesian approach to full dust models, including realistic optical properties, stochastic heating, and the mixing of physical conditions in the observed regions. We test the performances of our model by applying it to synthetic observations. We explore the impact on the recovered parameters of several effects: signal-to-noise ratio, SED shape, sample size, the presence of intrinsic correlations, the wavelength coverage, and the use of different SED model components. We show that this method is very efficient: the recovered parameters are consistently distributed around their true values. We do not find any clear bias, even for the most degenerate parameters, or with extreme signal-to-noise ratios.
Spectral Neugebauer-based color halftone prediction model accounting for paper fluorescence.
Hersch, Roger David
2014-08-20
We present a spectral model for predicting the fluorescent emission and the total reflectance of color halftones printed on optically brightened paper. By relying on extended Neugebauer models, the proposed model accounts for the attenuation by the ink halftones of both the incident exciting light in the UV wavelength range and the emerging fluorescent emission in the visible wavelength range. The total reflectance is predicted by adding the predicted fluorescent emission relative to the incident light and the pure reflectance predicted with an ink-spreading enhanced Yule-Nielsen modified Neugebauer reflectance prediction model. The predicted fluorescent emission spectrum as a function of the amounts of cyan, magenta, and yellow inks is very accurate. It can be useful to paper and ink manufacturers who would like to study in detail the contribution of the fluorescent brighteners and the attenuation of the fluorescent emission by ink halftones.
Viner, K.; Reinecke, P. A.; Gabersek, S.; Flagg, D. D.; Doyle, J. D.; Martini, M.; Ryglicki, D.; Michalakes, J.; Giraldo, F.
2016-12-01
NEPTUNE: the Navy Environmental Prediction sysTem Using the NUMA*corE, is a 3D spectral element atmospheric model composed of a full suite of physics parameterizations and pre- and post-processing infrastructure with plans for data assimilation and coupling components to a variety of Earth-system models. This talk will focus on the initial struggles and solutions in adapting NUMA for stable and accurate integration on the sphere using both the deep atmosphere equations and a newly developed shallow-atmosphere approximation, as demonstrated through idealized test cases. In addition, details of the physics-dynamics coupling methodology will be discussed. NEPTUNE results for test cases from the 2016 Dynamical Core Model Intercomparison Project (DCMIP-2016) will be shown and discussed. *NUMA: Nonhydrostatic Unified Model of the Atmosphere; Kelly and Giraldo 2012, JCP
Spectral-element Method for 3D Marine Controlled-source EM Modeling
Liu, L.; Yin, C.; Zhang, B., Sr.; Liu, Y.; Qiu, C.; Huang, X.; Zhu, J.
2017-12-01
As one of the predrill reservoir appraisal methods, marine controlled-source EM (MCSEM) has been widely used in mapping oil reservoirs to reduce risk of deep water exploration. With the technical development of MCSEM, the need for improved forward modeling tools has become evident. We introduce in this paper spectral element method (SEM) for 3D MCSEM modeling. It combines the flexibility of finite-element and high accuracy of spectral method. We use Galerkin weighted residual method to discretize the vector Helmholtz equation, where the curl-conforming Gauss-Lobatto-Chebyshev (GLC) polynomials are chosen as vector basis functions. As a kind of high-order complete orthogonal polynomials, the GLC have the characteristic of exponential convergence. This helps derive the matrix elements analytically and improves the modeling accuracy. Numerical 1D models using SEM with different orders show that SEM method delivers accurate results. With increasing SEM orders, the modeling accuracy improves largely. Further we compare our SEM with finite-difference (FD) method for a 3D reservoir model (Figure 1). The results show that SEM method is more effective than FD method. Only when the mesh is fine enough, can FD achieve the same accuracy of SEM. Therefore, to obtain the same precision, SEM greatly reduces the degrees of freedom and cost. Numerical experiments with different models (not shown here) demonstrate that SEM is an efficient and effective tool for MSCEM modeling that has significant advantages over traditional numerical methods.This research is supported by Key Program of National Natural Science Foundation of China (41530320), China Natural Science Foundation for Young Scientists (41404093), and Key National Research Project of China (2016YFC0303100, 2017YFC0601900).
Melting spectral functions of the scalar and vector mesons in a holographic QCD model
International Nuclear Information System (INIS)
Fujita, Mitsutoshi; Kikuchi, Toru; Fukushima, Kenji; Misumi, Tatsuhiro; Murata, Masaki
2010-01-01
We investigate the finite-temperature spectral functions of heavy quarkonia by using the soft-wall anti-de Sitter/QCD model. We discuss the scalar, the pseudoscalar, the vector, and the axial-vector mesons and compare their qualitative features of the melting temperature and growing width. We find that the axial-vector meson melts earlier than the vector meson, while there appears only a slight difference between the scalar and pseudoscalar mesons, which also melt earlier than the vector meson.
Immunological effects of irradiation: waiting for a model
International Nuclear Information System (INIS)
Doria, G.
1979-01-01
Decreased resistance to pathogens, is an effect of ionizing radiations, is largely mediated by impairment of the specific immune response. It has been established that the antibody response is depressed when the antigen is injected shortly before or immediately after irradiation. Recovery of the response in animals immunized after sublethal irradiation starts after about 1 week and may be complete 2 months after irradiation. If animals are immunized a few or several days before radiation exposure, some parameters of the antibody response are unaffected while others may display lower or higher values than normal, depending on the nature and physical form of the antigen. Recent studies have described the effects of whole-body irradiation on antibody ability. Since this antibody property affects the stability of immune complexes and, therefore, the antibody's ability to neutralize viruses and toxins, affinity was felt to be of importance to counteract infections in irradiated animals. Antibody affinity was found up to 20 times greater in irradiated than in control mice when antigen was injected 1 to 5 days before or 2 hr to 8 weeks after a sublethal dose of x-rays. Recovery profiles of mitotic responses of spleen cells to PHA, ConA, or LPS suggest that the enhancement of antibody affinity in irradiated mice could result from a relative lack of suppressor T cells. Dysfunctions of the immune system of irradiated animals can be attributed to alterations of the populations of immunologically competent cells. Unlike auxiliary cells, lymphocytes are extremely sensitive to ionizing radiations. Subpopulations of T and B lymphocytes appear to have different radiosensitivities and to develop with different efficiencies in irradiated animals. B cells seem to be more radiosensitive and to recover faster than T cells
Modeling Climate Responses to Spectral Solar Forcing on Centennial and Decadal Time Scales
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.
SPATIAL AND SPECTRAL MODELING OF THE GAMMA-RAY DISTRIBUTION IN THE LARGE MAGELLANIC CLOUD
Energy Technology Data Exchange (ETDEWEB)
Foreman, Gary; Chu, You-Hua; Gruendl, Robert; Fields, Brian; Ricker, Paul [Department of Astronomy, University of Illinois, 1002 W. Green St., Urbana, IL 61801 (United States); Hughes, Annie, E-mail: gforema2@illinois.edu [Max-Planck-Institut für Astronomie, Königstuhl 17, D-69117 Heidelberg (Germany)
2015-07-20
We perform spatial and spectral analyses of the LMC gamma-ray emission collected over 66 months by the Fermi Gamma-ray Space Telescope. In our spatial analysis, we model the LMC cosmic-ray distribution and gamma-ray production using observed maps of the LMC interstellar medium, star formation history, interstellar radiation field, and synchrotron emission. We use bootstrapping of the data to quantify the robustness of spatial model performance. We model the LMC gamma-ray spectrum using fitting functions derived from the physics of π{sup 0} decay, Bremsstrahlung, and inverse Compton scattering. We find the integrated gamma-ray flux of the LMC from 200 MeV to 20 GeV to be 1.37 ± 0.02 × 10{sup −7} ph cm{sup −2} s{sup −1}, of which we attribute about 6% to inverse Compton scattering and 44% to Bremsstrahlung. From our work, we conclude that the spectral index of the LMC cosmic-ray proton population is 2.4 ± 0.2, and we find that cosmic-ray energy loss through gamma-ray production is concentrated within a few 100 pc of acceleration sites. Assuming cosmic-ray energy equipartition with magnetic fields, we estimate LMC cosmic rays encounter an average magnetic field strength ∼3 μG.
Spectral Behavior of a Linearized Land-Atmosphere Model: Applications to Hydrometeorology
Gentine, P.; Entekhabi, D.; Polcher, J.
2008-12-01
The present study develops an improved version of the linearized land-atmosphere model first introduced by Lettau (1951). This model is used to investigate the spectral response of land-surface variables to a daily forcing of incoming radiation at the land-surface. An analytical solution of the problem is found in the form of temporal Fourier series and gives the atmospheric boundary-layer and soil profiles of state variables (potential temperature, specific humidity, sensible and latent heat fluxes). Moreover the spectral dependency of surface variables is expressed as function of land-surface parameters (friction velocity, vegetation height, aerodynamic resistance, stomatal conductance). This original approach has several advantages: First, the model only requires little data to work and perform well: only time series of incoming radiation at the land-surface, mean specific humidity and temperature at any given height are required. These inputs being widely available over the globe, the model can easily be run and tested under various conditions. The model will also help analysing the diurnal shape and frequency dependency of surface variables and soil-ABL profiles. In particular, a strong emphasis is being placed on the explanation and prediction of Evaporative Fraction (EF) and Bowen Ratio diurnal shapes. EF is shown to remain a diurnal constant under restricting conditions: fair and dry weather, with strong solar radiation and no clouds. Moreover, the EF pseudo-constancy value is found and given as function of surface parameters, such as aerodynamic resistance and stomatal conductance. Then, application of the model for the conception of remote-sensing tools, according to the temporal resolution of the sensor, will also be discussed. Finally, possible extensions and improvement of the model will be discussed.
Computing Models of M-type Host Stars and their Panchromatic Spectral Output
Linsky, Jeffrey; Tilipman, Dennis; France, Kevin
2018-06-01
We have begun a program of computing state-of-the-art model atmospheres from the photospheres to the coronae of M stars that are the host stars of known exoplanets. For each model we are computing the emergent radiation at all wavelengths that are critical for assessingphotochemistry and mass-loss from exoplanet atmospheres. In particular, we are computing the stellar extreme ultraviolet radiation that drives hydrodynamic mass loss from exoplanet atmospheres and is essential for determing whether an exoplanet is habitable. The model atmospheres are computed with the SSRPM radiative transfer/statistical equilibrium code developed by Dr. Juan Fontenla. The code solves for the non-LTE statistical equilibrium populations of 18,538 levels of 52 atomic and ion species and computes the radiation from all species (435,986 spectral lines) and about 20,000,000 spectral lines of 20 diatomic species.The first model computed in this program was for the modestly active M1.5 V star GJ 832 by Fontenla et al. (ApJ 830, 152 (2016)). We will report on a preliminary model for the more active M5 V star GJ 876 and compare this model and its emergent spectrum with GJ 832. In the future, we will compute and intercompare semi-empirical models and spectra for all of the stars observed with the HST MUSCLES Treasury Survey, the Mega-MUSCLES Treasury Survey, and additional stars including Proxima Cen and Trappist-1.This multiyear theory program is supported by a grant from the Space Telescope Science Institute.
A Perceptual Model for Sinusoidal Audio Coding Based on Spectral Integration
Directory of Open Access Journals (Sweden)
Jensen Søren Holdt
2005-01-01
Full Text Available Psychoacoustical models have been used extensively within audio coding applications over the past decades. Recently, parametric coding techniques have been applied to general audio and this has created the need for a psychoacoustical model that is specifically suited for sinusoidal modelling of audio signals. In this paper, we present a new perceptual model that predicts masked thresholds for sinusoidal distortions. The model relies on signal detection theory and incorporates more recent insights about spectral and temporal integration in auditory masking. As a consequence, the model is able to predict the distortion detectability. In fact, the distortion detectability defines a (perceptually relevant norm on the underlying signal space which is beneficial for optimisation algorithms such as rate-distortion optimisation or linear predictive coding. We evaluate the merits of the model by combining it with a sinusoidal extraction method and compare the results with those obtained with the ISO MPEG-1 Layer I-II recommended model. Listening tests show a clear preference for the new model. More specifically, the model presented here leads to a reduction of more than 20% in terms of number of sinusoids needed to represent signals at a given quality level.
International Nuclear Information System (INIS)
Pineau, L.; Landron, C.
2015-01-01
In this paper, an analysis of tensile data acquired as part of the French Reactor Vessel Surveillance Program (RVSP) is produced. This program contains amongst other mechanical tests, tensile tests at 20 and 300 C degrees on non irradiated base metals and at 300 C degrees only on irradiated materials. It shows that irradiation leads to an increase in the yield strength and a decrease in the strain hardening. The exploitation of tensile results has permitted to express a relationship between yield strength increase measured and fluence value, as well as between strain hardening decrease and yield strength evolution. The use of these relations in the aim at predicting evolution of tensile properties with irradiation has then permitted to propose a methodology to model entire stress-strain curves of irradiated base metal only based on the non irradiated stress-strain curve. These predictions were successfully compared with an experimental standard case. (authors)
Construction of a reliable model pyranometer for irradiance ...
African Journals Online (AJOL)
USER
2010-03-22
Mar 22, 2010 ... Key words: Solar radiation, pyranometer, photodiode, irradiance. INTRODUCTION ... used in meteorology, climate- logy, agriculture, solar energy studies and building ..... Renewable Energy, 9: 30-33. Energy Commission of ...
International Nuclear Information System (INIS)
Barukčić, M.; Ćorluka, V.; Miklošević, K.
2015-01-01
Highlights: • The temperature and irradiance dependent model for the I–V curve estimation is presented. • The purely mathematical model based on the analysis of the I–V curve shape is presented. • The model includes the Gompertz function with temperature and irradiance dependent parameters. • The input data are extracted from the data sheet I–V curves. - Abstract: The temperature and irradiance dependent mathematical model for photovoltaic panel performances estimation is proposed in the paper. The base of the model is the mathematical function of the photovoltaic panel current–voltage curve. The model of the current–voltage curve is based on the sigmoid function with temperature and irradiance dependent parameters. The temperature and irradiance dependencies of the parameters are proposed in the form of analytic functions. The constant parameters are involved in the analytical functions. The constant parameters need to be estimated to get the temperature and irradiance dependent current–voltage curve. The mathematical model contains 12 constant parameters and they are estimated by using the evolutionary algorithm. The optimization problem is defined for this purpose. The optimization problem objective function is based on estimated and extracted (measured) current and voltage values. The current and voltage values are extracted from current–voltage curves given in datasheet of the photovoltaic panels. The new procedure for estimation of open circuit voltage value at any temperature and irradiance is proposed in the model. The performance of the proposed mathematical model is presented for three different photovoltaic panel technologies. The simulation results indicate that the proposed mathematical model is acceptable for estimation of temperature and irradiance dependent current–voltage curve and photovoltaic panel performances within temperature and irradiance ranges
Mayr, Hans G.; Mengel, J. G.; Chan, K. L.; Huang, F. T.
2010-01-01
As Lindzen (1981) had shown, small-scale gravity waves (GW) produce the observed reversals of the zonal-mean circulation and temperature variations in the upper mesosphere. The waves also play a major role in modulating and amplifying the diurnal tides (DT) (e.g., Waltersheid, 1981; Fritts and Vincent, 1987; Fritts, 1995a). We summarize here the modeling studies with the mechanistic numerical spectral model (NSM) with Doppler spread parameterization for GW (Hines, 1997a, b), which describes in the middle atmosphere: (a) migrating and non-migrating DT, (b) planetary waves (PW), and (c) global-scale inertio gravity waves. Numerical experiments are discussed that illuminate the influence of GW filtering and nonlinear interactions between DT, PW, and zonal mean variations. Keywords: Theoretical modeling, Middle atmosphere dynamics, Gravity wave interactions, Migrating and non-migrating tides, Planetary waves, Global-scale inertio gravity waves.
Fission gas induced deformation model for FRAP-T6 and NSRR irradiated fuel test simulations
Energy Technology Data Exchange (ETDEWEB)
Nakamura, Takehiko; Sasajima, Hideo; Fuketa, Toyoshi [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment; Hosoyamada, Ryuji; Mori, Yukihide
1996-11-01
Pulse irradiation tests of irradiated fuels under simulated reactivity initiated accidents (RIAs) have been carried out at the Nuclear Safety Research Reactor (NSRR). Larger cladding diameter increase was observed in the irradiated fuel tests than in the previous fresh fuel tests. A fission gas induced cladding deformation model was developed and installed in a fuel behavior analysis code, FRAP-T6. The irradiated fuel tests were analyzed with the model in combination with modified material properties and fuel cracking models. In Test JM-4, where the cladding temperature rose to higher temperatures and grain boundary separation by the pulse irradiation was significant, the fission gas model described the cladding deformation reasonably well. The fuel had relatively flat radial power distribution and the grain boundary gas from the whole radius was calculated to contribute to the deformation. On the other hand, the power density in the irradiated LWR fuel rods in the pulse irradiation tests was remarkably higher at the fuel periphery than the center. A fuel thermal expansion model, GAPCON, which took account of the effect of fuel cracking by the temperature profile, was found to reproduce well the LWR fuel behavior with the fission gas deformation model. This report present details of the models and their NSRR test simulations. (author)
Modeling of dislocation channel width evolution in irradiated metals
Doyle, Peter J.; Benensky, Kelsa M.; Zinkle, Steven J.
2018-02-01
Defect-free dislocation channel formation has been reported to promote plastic instability during tensile testing via localized plastic flow, leading to a distinct loss of ductility and strain hardening in many low-temperature irradiated materials. In order to study the underlying mechanisms governing dislocation channel width and formation, the channel formation process is modeled via a simple stochastic dislocation-jog process dependent upon grain size, defect cluster density, and defect size. Dislocations traverse a field of defect clusters and jog stochastically upon defect interaction, forming channels of low defect-density. Based upon prior molecular dynamics (MD) simulations and in-situ experimental transmission electron microscopy (TEM) observations, each dislocation encounter with a dislocation loop or stacking fault tetrahedron (SFT) is assumed to cause complete absorption of the defect cluster, prompting the dislocation to jog up or down by a distance equal to half the defect cluster diameter. Channels are predicted to form rapidly and are comparable to reported TEM measurements for many materials. Predicted channel widths are found to be most strongly dependent on mean defect size and correlated well with a power law dependence on defect diameter and density, and distance from the dislocation source. Due to the dependence of modeled channel width on defect diameter and density, maximum channel width is predicted to slowly increase as accumulated dose increases. The relatively weak predicted dependence of channel formation width with distance, in accordance with a diffusion analogy, implies that after only a few microns from the source, most channels observed via TEM analyses may not appear to vary with distance because of limitations in the field-of-view to a few microns. Further, examinations of the effect of the so-called "source-broadening" mechanism of channel formation showed that its effect is simply to add a minimum thickness to the channel
Zeyada, H M; Makhlouf, M M; El-Nahass, M M
2015-09-05
In this work, we report on the effect of γ-ray irradiation and annealing temperature on the optical properties of metal-free tetraphenylporphyrin, H2TPP, and zinc tetraphenylporphyrin, ZnTPP, thin films. Thin films of H2TPP and ZnTPP were successfully prepared by the thermal evaporation technique. The optical properties of H2TPP and ZnTPP films were investigated using spectrophotometric measurements of the transmittance and reflectance at normal incidence of light in the wavelength range from 200 to 2500 nm. The absorption spectra of H2TPP showed four absorption bands, namely the Q, B, N and M bands. The effect of inserting Zn atom into the cavity of porphyrin macrocycle in ZnTPP molecule distorted the Q and B bands, reduced the width of absorption region and influenced the optical constants and dispersion parameters. In all conditions, the type of electron transition is indirect allowed transition. Anomalous dispersion is observed in the absorption region but normal dispersion occurs in the transparent region of spectra. We adopted multi-oscillator model and the single oscillator model to interpret the anomalous and normal dispersion, respectively. We have found that the annealing temperature has mostly the opposite effect of γ-ray irradiation on absorption and dispersion characteristics of these films. Copyright © 2015 Elsevier B.V. All rights reserved.
Impacts of using spectral nudging on regional climate model RCA4 simulations of the Arctic
Directory of Open Access Journals (Sweden)
P. Berg
2013-06-01
Full Text Available The performance of the Rossby Centre regional climate model RCA4 is investigated for the Arctic CORDEX (COordinated Regional climate Downscaling EXperiment region, with an emphasis on its suitability to be coupled to a regional ocean and sea ice model. Large biases in mean sea level pressure (MSLP are identified, with pronounced too-high pressure centred over the North Pole in summer of over 5 hPa, and too-low pressure in winter of a similar magnitude. These lead to biases in the surface winds, which will potentially lead to strong sea ice biases in a future coupled system. The large-scale circulation is believed to be the major reason for the biases, and an implementation of spectral nudging is applied to remedy the problems by constraining the large-scale components of the driving fields within the interior domain. It is found that the spectral nudging generally corrects for the MSLP and wind biases, while not significantly affecting other variables, such as surface radiative components, two-metre temperature and precipitation.
Spero, Tanya L.; Otte, Martin J.; Bowden, Jared H.; Nolte, Christopher G.
2014-10-01
Spectral nudging—a scale-selective interior constraint technique—is commonly used in regional climate models to maintain consistency with large-scale forcing while permitting mesoscale features to develop in the downscaled simulations. Several studies have demonstrated that spectral nudging improves the representation of regional climate in reanalysis-forced simulations compared with not using nudging in the interior of the domain. However, in the Weather Research and Forecasting (WRF) model, spectral nudging tends to produce degraded precipitation simulations when compared to analysis nudging—an interior constraint technique that is scale indiscriminate but also operates on moisture fields which until now could not be altered directly by spectral nudging. Since analysis nudging is less desirable for regional climate modeling because it dampens fine-scale variability, changes are proposed to the spectral nudging methodology to capitalize on differences between the nudging techniques and aim to improve the representation of clouds, radiation, and precipitation without compromising other fields. These changes include adding spectral nudging toward moisture, limiting nudging to below the tropopause, and increasing the nudging time scale for potential temperature, all of which collectively improve the representation of mean and extreme precipitation, 2 m temperature, clouds, and radiation, as demonstrated using a model-simulated 20 year historical period. Such improvements to WRF may increase the fidelity of regional climate data used to assess the potential impacts of climate change on human health and the environment and aid in climate change mitigation and adaptation studies.
Energy Technology Data Exchange (ETDEWEB)
Furlan, E. [Infrared Processing and Analysis Center, California Institute of Technology, 770 S. Wilson Ave., Pasadena, CA 91125 (United States); Fischer, W. J. [Goddard Space Flight Center, 8800 Greenbelt Road, Greenbelt, MD 20771 (United States); Ali, B. [Space Science Institute, 4750 Walnut Street, Boulder, CO 80301 (United States); Stutz, A. M. [Max-Planck-Institut für Astronomie, Königstuhl 17, D-69117 Heidelberg (Germany); Stanke, T. [ESO, Karl-Schwarzschild-Strasse 2, D-85748 Garching bei München (Germany); Tobin, J. J. [National Radio Astronomy Observatory, Charlottesville, VA 22903 (United States); Megeath, S. T.; Booker, J. [Ritter Astrophysical Research Center, Department of Physics and Astronomy, University of Toledo, 2801 W. Bancroft Street, Toledo, OH 43606 (United States); Osorio, M. [Instituto de Astrofísica de Andalucía, CSIC, Camino Bajo de Huétor 50, E-18008 Granada (Spain); Hartmann, L.; Calvet, N. [Department of Astronomy, University of Michigan, 500 Church Street, Ann Arbor, MI 48109 (United States); Poteet, C. A. [New York Center for Astrobiology, Rensselaer Polytechnic Institute, 110 Eighth Street, Troy, NY 12180 (United States); Manoj, P. [Department of Astronomy and Astrophysics, Tata Institute of Fundamental Research, Homi Bhabha Road, Colaba, Mumbai 400005 (India); Watson, D. M. [Department of Physics and Astronomy, University of Rochester, Rochester, NY 14627 (United States); Allen, L., E-mail: furlan@ipac.caltech.edu [National Optical Astronomy Observatory, 950 N. Cherry Avenue, Tucson, AZ 85719 (United States)
2016-05-01
We present key results from the Herschel Orion Protostar Survey: spectral energy distributions (SEDs) and model fits of 330 young stellar objects, predominantly protostars, in the Orion molecular clouds. This is the largest sample of protostars studied in a single, nearby star formation complex. With near-infrared photometry from 2MASS, mid- and far-infrared data from Spitzer and Herschel , and submillimeter photometry from APEX, our SEDs cover 1.2–870 μ m and sample the peak of the protostellar envelope emission at ∼100 μ m. Using mid-IR spectral indices and bolometric temperatures, we classify our sample into 92 Class 0 protostars, 125 Class I protostars, 102 flat-spectrum sources, and 11 Class II pre-main-sequence stars. We implement a simple protostellar model (including a disk in an infalling envelope with outflow cavities) to generate a grid of 30,400 model SEDs and use it to determine the best-fit model parameters for each protostar. We argue that far-IR data are essential for accurate constraints on protostellar envelope properties. We find that most protostars, and in particular the flat-spectrum sources, are well fit. The median envelope density and median inclination angle decrease from Class 0 to Class I to flat-spectrum protostars, despite the broad range in best-fit parameters in each of the three categories. We also discuss degeneracies in our model parameters. Our results confirm that the different protostellar classes generally correspond to an evolutionary sequence with a decreasing envelope infall rate, but the inclination angle also plays a role in the appearance, and thus interpretation, of the SEDs.
Distraction osteogenesis after irradiation in a rabbit model
International Nuclear Information System (INIS)
Tsuchiya, Hiroyuki; Uehara, Kenji; Sakurakichi, Keisuke; Watanabe, Koji; Matsubara, Hidenori; Tomita, Katsuro
2005-01-01
The present study was performed to investigate the effects of preoperative irradiation on distraction osteogenesis, as little is known about how preoperative irradiation delays distraction osteogenesis. A single dose of irradiation was applied to the right rear legs of rabbits. This was followed by tibial lengthening at a rate of 0.5 mm/day, which was continued for 4 weeks. Bone regeneration was examined radiographically and histologically. In the irradiation group, the radiographs showed little regeneration during the elongation phase. During the maturation phase, the callus appeared slowly, and its formation was spotty. Furthermore, regeneration was not completed until the fourth week of the maturation period. Histological examination at the end of distraction showed a gap in the distraction consisting of loose connective tissue, with part of the fibrous tissue oriented longitudinally. Four weeks after completion of distraction, the major part of the radiolucent region consisted of cartilage. The spotty osteogenesis was identified as enchondral ossification. Immunohistochemical examination of the regeneration area revealed that the blood vessels were extremely localized, and that the level of expression of vascular endothelial growth factor (VEGF) in the osteoblasts was high. Microangiography showed that vascularization at the distracted sites was poor. Distraction osteogenesis was decreased markedly by preoperative irradiation in terms of both rate and process. The results suggested that most of the osteoprogenitor cells were damaged immediately after irradiation. The high level of VEGF in the osteoblasts and the enchondral ossification also suggested a hypoxic state in the distracted region. Preoperative irradiation interferes with distraction osteogenesis by inducing a state of poor angiogenesis. (author)
Model of defect reactions and the influence of clustering in pulse-neutron-irradiated Si
International Nuclear Information System (INIS)
Myers, S. M.; Cooper, P. J.; Wampler, W. R.
2008-01-01
Transient reactions among irradiation defects, dopants, impurities, and carriers in pulse-neutron-irradiated Si were modeled taking into account the clustering of the primal defects in recoil cascades. Continuum equations describing the diffusion, field drift, and reactions of relevant species were numerically solved for a submicrometer spherical volume, within which the starting radial distributions of defects could be varied in accord with the degree of clustering. The radial profiles corresponding to neutron irradiation were chosen through pair-correlation-function analysis of vacancy and interstitial distributions obtained from the binary-collision code MARLOWE, using a spectrum of primary recoil energies computed for a fast-burst fission reactor. Model predictions of transient behavior were compared with a variety of experimental results from irradiated bulk Si, solar cells, and bipolar-junction transistors. The influence of defect clustering during neutron bombardment was further distinguished through contrast with electron irradiation, where the primal point defects are more uniformly dispersed
Tong, Hao; Xu, Renxin
2013-03-01
The X-ray dim isolated neutron stars (XDINSs) are peculiar pulsar-like objects, characterized by their very well Planck-like spectrum. In studying their spectral energy distributions, the optical/UV excess is a long standing problem. Recently, Kaplan et al. (2011) have measured the optical/UV excess for all seven sources, which is understandable in the resonant cyclotron scattering (RCS) model previously addressed. The RCS model calculations show that the RCS process can account for the observed optical/UV excess for most sources. The flat spectrum of RX J2143.0+0654 may due to contribution from bremsstrahlung emission of the electron system in addition to the RCS process.
Contraction Options and Optimal Multiple-Stopping in Spectrally Negative Lévy Models
Energy Technology Data Exchange (ETDEWEB)
Yamazaki, Kazutoshi, E-mail: kyamazak@kansai-u.ac.jp [Kansai University, Department of Mathematics, Faculty of Engineering Science (Japan)
2015-08-15
This paper studies the optimal multiple-stopping problem arising in the context of the timing option to withdraw from a project in stages. The profits are driven by a general spectrally negative Lévy process. This allows the model to incorporate sudden declines of the project values, generalizing greatly the classical geometric Brownian motion model. We solve the one-stage case as well as the extension to the multiple-stage case. The optimal stopping times are of threshold-type and the value function admits an expression in terms of the scale function. A series of numerical experiments are conducted to verify the optimality and to evaluate the efficiency of the algorithm.
International Nuclear Information System (INIS)
Gneiding, N.; Zhuromskyy, O.; Peschel, U.; Shamonina, E.
2014-01-01
Metamaterials are comprised of metallic structures with a strong response to incident electromagnetic radiation, like, for example, split ring resonators. The interaction of resonator ensembles with electromagnetic waves can be simulated with finite difference or finite elements algorithms, however, above a certain ensemble size simulations become inadmissibly time or memory consuming. Alternatively a circuit description of metamaterials, a well developed modelling tool at radio and microwave frequencies, allows to significantly increase the simulated ensemble size. This approach can be extended to the IR spectral range with an appropriate set of circuit element parameters accounting for physical effects such as electron inertia and finite conductivity. The model is verified by comparing the coupling coefficients with the ones obtained from the full wave numerical simulations, and used to optimize the nano-antenna design with improved radiation characteristics.
Contraction Options and Optimal Multiple-Stopping in Spectrally Negative Lévy Models
International Nuclear Information System (INIS)
Yamazaki, Kazutoshi
2015-01-01
This paper studies the optimal multiple-stopping problem arising in the context of the timing option to withdraw from a project in stages. The profits are driven by a general spectrally negative Lévy process. This allows the model to incorporate sudden declines of the project values, generalizing greatly the classical geometric Brownian motion model. We solve the one-stage case as well as the extension to the multiple-stage case. The optimal stopping times are of threshold-type and the value function admits an expression in terms of the scale function. A series of numerical experiments are conducted to verify the optimality and to evaluate the efficiency of the algorithm
Analytic models of spectral responses of fiber-grating-based interferometers on FMC theory.
Zeng, Xiangkai; Wei, Lai; Pan, Yingjun; Liu, Shengping; Shi, Xiaohui
2012-02-13
In this paper the analytic models (AMs) of the spectral responses of fiber-grating-based interferometers are derived from the Fourier mode coupling (FMC) theory proposed recently. The interferometers include Fabry-Perot cavity, Mach-Zehnder and Michelson interferometers, which are constructed by uniform fiber Bragg gratings and long-period fiber gratings, and also by Gaussian-apodized ones. The calculated spectra based on the analytic models are achieved, and compared with the measured cases and those on the transfer matrix (TM) method. The calculations and comparisons have confirmed that the AM-based spectrum is in excellent agreement with the TM-based one and the measured case, of which the efficiency is improved up to ~2990 times that of the TM method for non-uniform-grating-based in-fiber interferometers.
Recent developments in the super transition array model for spectral simulation of LTE plasmas
International Nuclear Information System (INIS)
Bar-Shalom, A.; Oreg, J.; Goldstein, W.H.
1992-01-01
Recently developed sub-picosecond pulse lasers have been used to create hot, near solid density plasmas. Since these plasmas are nearly in local thermodynamic equilibrium (LTE), their emission spectra involve a huge number of populated configurations. A typical spectrum is a combination of many unresolved clusters of emission, each containing an immense number of overlapping, unresolvable bound-bound and bound-free transitions. Under LTE, or near LTE conditions, traditional detailed configuration or detailed term spectroscopic models are not capable of handling the vast number of transitions involved. The average atom (AA) model, on the other hand, accounts for all relevant transitions, but in an oversimplified fashion that ignores all spectral structure. The Super Transition Array (STA) model, which has been developed in recent years, combines the simplicity and comprehensiveness of the AA model with the accuracy of detailed term accounting. The resolvable structure of spectral clusters is revealed by successively increasing the number of distinct STA's, until convergence is attained. The limit of this procedure is a detailed unresolved transition array (UTA) spectrum, with a term-broadened line for each accessible configuration-to-configuration transition, weighted by the relevant Boltzman population. In practice, this UTA spectrum is actually obtained using only a few thousand to tens of thousands of STA's (as opposed, typically, to billions of UTAs). The central result of STA theory is a set of formulas for the moments (total intensity, average transition energy, variance) of an STA. In calculating the moments, detailed relativistic first order quantum transition energies and probabilities are used. The energy appearing in the Boltzman factor associated with each level in a superconfiguration is the zero order result corrected by a superconfiguration averaged first order correction. Examples and application to recent measurements are presented
Energy Technology Data Exchange (ETDEWEB)
Posadillo, R.; Lopez Luque, R. [Grupo de Investigacion de Fisica para las Energias y Recursos Renovables, Dpto. de Fisica Aplicada, UCO, Edificio C2 Campus de Rabanales, 14071 Cordoba (Spain)
2010-04-15
An analysis of models for the estimation of hourly diffuse irradiation based on the interrelations between the hourly diffuse fraction k{sub d} and the hourly clearness index k{sub t}, has concluded that k{sub t} is not a sufficient variable for parametrizing the effect of clouds on diffuse irradiation. A detailed study of the dispersion recorded by this diffuse component for a specific clearness index under partly cloudy sky conditions has led to analyzing how the variability in the instantaneous clearness index influences this dispersion. The data sets correspond to 10 years of hourly and instantaneous value records of global and diffuse radiation collected in Cordoba, Spain. In addition to the inclusion of the sine of solar elevation as a variable into the k{sub d}-k{sub t} correlations, this model propose the inclusion of others parameters related to the variability in the normalized clearness index within an hour and with the fluctuations presented by the time series of the instantaneous values of that index. Also presented is the implementation of an algorithm permitting both the determination of the hourly diffuse irradiation and the discrimination between the different sky conditions in those situations known by the designation partly cloudy sky. (author)
International Nuclear Information System (INIS)
Posadillo, R.; Lopez Luque, R.
2010-01-01
An analysis of models for the estimation of hourly diffuse irradiation based on the interrelations between the hourly diffuse fraction k d and the hourly clearness index k t , has concluded that k t is not a sufficient variable for parametrizing the effect of clouds on diffuse irradiation. A detailed study of the dispersion recorded by this diffuse component for a specific clearness index under partly cloudy sky conditions has led to analyzing how the variability in the instantaneous clearness index influences this dispersion. The data sets correspond to 10 years of hourly and instantaneous value records of global and diffuse radiation collected in Cordoba, Spain. In addition to the inclusion of the sine of solar elevation as a variable into the k d -k t correlations, this model propose the inclusion of others parameters related to the variability in the normalized clearness index within an hour and with the fluctuations presented by the time series of the instantaneous values of that index. Also presented is the implementation of an algorithm permitting both the determination of the hourly diffuse irradiation and the discrimination between the different sky conditions in those situations known by the designation partly cloudy sky.
A spectral nudging method for the ACCESS1.3 atmospheric model
Uhe, P.; Thatcher, M.
2015-06-01
A convolution-based method of spectral nudging of atmospheric fields is developed in the Australian Community Climate and Earth Systems Simulator (ACCESS) version 1.3 which uses the UK Met Office Unified Model version 7.3 as its atmospheric component. The use of convolutions allow for flexibility in application to different atmospheric grids. An approximation using one-dimensional convolutions is applied, improving the time taken by the nudging scheme by 10-30 times compared with a version using a two-dimensional convolution, without measurably degrading its performance. Care needs to be taken in the order of the convolutions and the frequency of nudging to obtain the best outcome. The spectral nudging scheme is benchmarked against a Newtonian relaxation method, nudging winds and air temperature towards ERA-Interim reanalyses. We find that the convolution approach can produce results that are competitive with Newtonian relaxation in both the effectiveness and efficiency of the scheme, while giving the added flexibility of choosing which length scales to nudge.
Ali-Haïmoud, Yacine; Chluba, Jens; Kamionkowski, Marc
2015-08-14
We propose a new method to constrain elastic scattering between dark matter (DM) and standard model particles in the early Universe. Direct or indirect thermal coupling of nonrelativistic DM with photons leads to a heat sink for the latter. This results in spectral distortions of the cosmic microwave background (CMB), the amplitude of which can be as large as a few times the DM-to-photon-number ratio. We compute CMB spectral distortions due to DM-proton, DM-electron, and DM-photon scattering for generic energy-dependent cross sections and DM mass m_{χ}≳1 keV. Using Far-Infrared Absolute Spectrophotometer measurements, we set constraints on the cross sections for m_{χ}≲0.1 MeV. In particular, for energy-independent scattering we obtain σ_{DM-proton}≲10^{-24} cm^{2} (keV/m_{χ})^{1/2}, σ_{DM-electron}≲10^{-27} cm^{2} (keV/m_{χ})^{1/2}, and σ_{DM-photon}≲10^{-39} cm^{2} (m_{χ}/keV). An experiment with the characteristics of the Primordial Inflation Explorer would extend the regime of sensitivity up to masses m_{χ}~1 GeV.
A spectral nudging method for the ACCESS1.3 atmospheric model
Directory of Open Access Journals (Sweden)
P. Uhe
2015-06-01
Full Text Available A convolution-based method of spectral nudging of atmospheric fields is developed in the Australian Community Climate and Earth Systems Simulator (ACCESS version 1.3 which uses the UK Met Office Unified Model version 7.3 as its atmospheric component. The use of convolutions allow for flexibility in application to different atmospheric grids. An approximation using one-dimensional convolutions is applied, improving the time taken by the nudging scheme by 10–30 times compared with a version using a two-dimensional convolution, without measurably degrading its performance. Care needs to be taken in the order of the convolutions and the frequency of nudging to obtain the best outcome. The spectral nudging scheme is benchmarked against a Newtonian relaxation method, nudging winds and air temperature towards ERA-Interim reanalyses. We find that the convolution approach can produce results that are competitive with Newtonian relaxation in both the effectiveness and efficiency of the scheme, while giving the added flexibility of choosing which length scales to nudge.
Fox, J. B.; Thayer, D. W.; Phillips, J. G.
The effect of low dose γ-irradiation on the thiamin content of ground pork was studied in the range of 0-14 kGy at 2°C and at radiation doses from 0.5 to 7 kGy at temperatures -20, 10, 0, 10 and 20°C. The detailed study at 2°C showed that loss of thiamin was exponential down to 0kGy. An exponential expression was derived for the effect of radiation dose and temperature of irradiation on thiamin loss, and compared with a previously derived general linear expression. Both models were accurate depictions of the data, but the exponential expression showed a significant decrease in the rate of loss between 0 and -10°C. This is the range over which water in meat freezes, the decrease being due to the immobolization of reactive radiolytic products of water in ice crystals.
Energy Technology Data Exchange (ETDEWEB)
Pouget, V.; Lapuyade, H.; Lewis, D.; Deval, Y.; Fouillat, P. [Bordeaux-1 Univ., IXL, 33 - Talence (France); Sarger, L. [Bordeaux-1 Univ., CPMOH, 33 - Talence (France)
1999-07-01
A new SPICE model of irradiated MOSFET taking into account the real response of the 4 electrodes is proposed. The component that has been simulated is an NMOS transistor issued from the AMS BiCMOS 0.8 {mu}m technology. A comparison between SPICE-generated transients and PISCES device simulation demonstrates the accuracy benefits when used in complex electronic architectures. This model could be used when designing electronic circuits able to sustain hardening due to SEE (single event effect), it will be an efficient complement to the physical simulations.
Chougule, Abhijit; Mann, Jakob; Kelly, Mark; Larsen, Gunner C.
2018-02-01
A spectral-tensor model of non-neutral, atmospheric-boundary-layer turbulence is evaluated using Eulerian statistics from single-point measurements of the wind speed and temperature at heights up to 100 m, assuming constant vertical gradients of mean wind speed and temperature. The model has been previously described in terms of the dissipation rate ɛ , the length scale of energy-containing eddies L , a turbulence anisotropy parameter Γ, the Richardson number Ri, and the normalized rate of destruction of temperature variance η _θ ≡ ɛ _θ /ɛ . Here, the latter two parameters are collapsed into a single atmospheric stability parameter z / L using Monin-Obukhov similarity theory, where z is the height above the Earth's surface, and L is the Obukhov length corresponding to Ri,η _θ. Model outputs of the one-dimensional velocity spectra, as well as cospectra of the streamwise and/or vertical velocity components, and/or temperature, and cross-spectra for the spatial separation of all three velocity components and temperature, are compared with measurements. As a function of the four model parameters, spectra and cospectra are reproduced quite well, but horizontal temperature fluxes are slightly underestimated in stable conditions. In moderately unstable stratification, our model reproduces spectra only up to a scale ˜ 1 km. The model also overestimates coherences for vertical separations, but is less severe in unstable than in stable cases.
Element-by-element parallel spectral-element methods for 3-D teleseismic wave modeling
Liu, Shaolin
2017-09-28
The development of an efficient algorithm for teleseismic wave field modeling is valuable for calculating the gradients of the misfit function (termed misfit gradients) or Fréchet derivatives when the teleseismic waveform is used for adjoint tomography. Here, we introduce an element-by-element parallel spectral-element method (EBE-SEM) for the efficient modeling of teleseismic wave field propagation in a reduced geology model. Under the plane-wave assumption, the frequency-wavenumber (FK) technique is implemented to compute the boundary wave field used to construct the boundary condition of the teleseismic wave incidence. To reduce the memory required for the storage of the boundary wave field for the incidence boundary condition, a strategy is introduced to efficiently store the boundary wave field on the model boundary. The perfectly matched layers absorbing boundary condition (PML ABC) is formulated using the EBE-SEM to absorb the scattered wave field from the model interior. The misfit gradient can easily be constructed in each time step during the calculation of the adjoint wave field. Three synthetic examples demonstrate the validity of the EBE-SEM for use in teleseismic wave field modeling and the misfit gradient calculation.
Efficient 3D frequency response modeling with spectral accuracy by the rapid expansion method
Chu, Chunlei
2012-07-01
Frequency responses of seismic wave propagation can be obtained either by directly solving the frequency domain wave equations or by transforming the time domain wavefields using the Fourier transform. The former approach requires solving systems of linear equations, which becomes progressively difficult to tackle for larger scale models and for higher frequency components. On the contrary, the latter approach can be efficiently implemented using explicit time integration methods in conjunction with running summations as the computation progresses. Commonly used explicit time integration methods correspond to the truncated Taylor series approximations that can cause significant errors for large time steps. The rapid expansion method (REM) uses the Chebyshev expansion and offers an optimal solution to the second-order-in-time wave equations. When applying the Fourier transform to the time domain wavefield solution computed by the REM, we can derive a frequency response modeling formula that has the same form as the original time domain REM equation but with different summation coefficients. In particular, the summation coefficients for the frequency response modeling formula corresponds to the Fourier transform of those for the time domain modeling equation. As a result, we can directly compute frequency responses from the Chebyshev expansion polynomials rather than the time domain wavefield snapshots as do other time domain frequency response modeling methods. When combined with the pseudospectral method in space, this new frequency response modeling method can produce spectrally accurate results with high efficiency. © 2012 Society of Exploration Geophysicists.
Model of the dose rate for a semi industrial irradiation plant. Pt. 2
International Nuclear Information System (INIS)
Mangusi, Josefina
2004-01-01
The second stage of the model for the absorbed dose rate in air for the enclosure of a half-industrialist irradiation plant operating with cobalt-60 sources holden in plan geometry is presented. The sensibility of the model with the treatment of the support structure of the irradiator is analyzed and verified with experimental measurements with good accord. The model of the absorbed dose rate in air in the case of an interposed material between the radioactive sources and the point of interest includes in its calculation a set of secondary radioactive sources created by the Compton scattering of the primary radiation. The accord of the calculated absorbed dose rate and the experimental measured ones is good. The transit dose due to the irradiator moving until its dwell position is also modeled. The isodose curves for a set of irradiator parallel planes are also generated. (author) [es
Modelling irradiation-induced softening in BCC iron by crystal plasticity approach
International Nuclear Information System (INIS)
Xiao, Xiazi; Terentyev, Dmitry; Yu, Long; Song, Dingkun; Bakaev, A.; Duan, Huiling
2015-01-01
Crystal plasticity model (CPM) for BCC iron to account for radiation-induced strain softening is proposed. CPM is based on the plastically-driven and thermally-activated removal of dislocation loops. Atomistic simulations are applied to parameterize dislocation-defect interactions. Combining experimental microstructures, defect-hardening/absorption rules from atomistic simulations, and CPM fitted to properties of non-irradiated iron, the model achieves a good agreement with experimental data regarding radiation-induced strain softening and flow stress increase under neutron irradiation. - Highlights: • A stress- and thermal-activated defect absorption model is proposed for the dislocation-loop interaction. • A temperature-dependent plasticity theory is proposed for the irradiation-induced strain softening of irradiated BCC metals. • The numerical results of the model match with the corresponding experimental data.
Modelling irradiation-induced softening in BCC iron by crystal plasticity approach
Energy Technology Data Exchange (ETDEWEB)
Xiao, Xiazi [State Key Laboratory for Turbulence and Complex System, Department of Mechanics and Engineering Science, College of Engineering, Peking University, Beijing 100871 (China); CAPT, HEDPS and IFSA Collaborative Innovation Center of MoE, Peking University, Beijing 100871 (China); Terentyev, Dmitry, E-mail: dterenty@SCKCEN.BE [Structural Material Group, Institute of Nuclear Materials Science, SCK-CEN, Mol (Belgium); Yu, Long; Song, Dingkun [State Key Laboratory for Turbulence and Complex System, Department of Mechanics and Engineering Science, College of Engineering, Peking University, Beijing 100871 (China); Bakaev, A. [Structural Material Group, Institute of Nuclear Materials Science, SCK-CEN, Mol (Belgium); Duan, Huiling, E-mail: hlduan@pku.edu.cn [State Key Laboratory for Turbulence and Complex System, Department of Mechanics and Engineering Science, College of Engineering, Peking University, Beijing 100871 (China); CAPT, HEDPS and IFSA Collaborative Innovation Center of MoE, Peking University, Beijing 100871 (China)
2015-11-15
Crystal plasticity model (CPM) for BCC iron to account for radiation-induced strain softening is proposed. CPM is based on the plastically-driven and thermally-activated removal of dislocation loops. Atomistic simulations are applied to parameterize dislocation-defect interactions. Combining experimental microstructures, defect-hardening/absorption rules from atomistic simulations, and CPM fitted to properties of non-irradiated iron, the model achieves a good agreement with experimental data regarding radiation-induced strain softening and flow stress increase under neutron irradiation. - Highlights: • A stress- and thermal-activated defect absorption model is proposed for the dislocation-loop interaction. • A temperature-dependent plasticity theory is proposed for the irradiation-induced strain softening of irradiated BCC metals. • The numerical results of the model match with the corresponding experimental data.
Energy Technology Data Exchange (ETDEWEB)
Kohnert, Aaron A.; Wirth, Brian D. [University of Tennessee, Knoxville, Tennessee 37996-2300 (United States)
2015-04-21
The microstructure that develops under low temperature irradiation in ferritic alloys is dominated by a high density of small (2–5 nm) defects. These defects have been widely observed to move via occasional discrete hops during in situ thin film irradiation experiments. Cluster dynamics models are used to describe the formation of these defects as an aggregation process of smaller clusters created as primary damage. Multiple assumptions regarding the mobility of these damage features are tested in the models, both with and without explicit consideration of such irradiation induced hops. Comparison with experimental data regarding the density of these defects demonstrates the importance of including such motions in a valid model. In particular, discrete hops inform the limited dependence of defect density on irradiation temperature observed in experiments, which the model was otherwise incapable of producing.
A fully Bayesian method for jointly fitting instrumental calibration and X-ray spectral models
International Nuclear Information System (INIS)
Xu, Jin; Yu, Yaming; Van Dyk, David A.; Kashyap, Vinay L.; Siemiginowska, Aneta; Drake, Jeremy; Ratzlaff, Pete; Connors, Alanna; Meng, Xiao-Li
2014-01-01
Owing to a lack of robust principled methods, systematic instrumental uncertainties have generally been ignored in astrophysical data analysis despite wide recognition of the importance of including them. Ignoring calibration uncertainty can cause bias in the estimation of source model parameters and can lead to underestimation of the variance of these estimates. We previously introduced a pragmatic Bayesian method to address this problem. The method is 'pragmatic' in that it introduced an ad hoc technique that simplified computation by neglecting the potential information in the data for narrowing the uncertainty for the calibration product. Following that work, we use a principal component analysis to efficiently represent the uncertainty of the effective area of an X-ray (or γ-ray) telescope. Here, however, we leverage this representation to enable a principled, fully Bayesian method that coherently accounts for the calibration uncertainty in high-energy spectral analysis. In this setting, the method is compared with standard analysis techniques and the pragmatic Bayesian method. The advantage of the fully Bayesian method is that it allows the data to provide information not only for estimation of the source parameters but also for the calibration product—here the effective area, conditional on the adopted spectral model. In this way, it can yield more accurate and efficient estimates of the source parameters along with valid estimates of their uncertainty. Provided that the source spectrum can be accurately described by a parameterized model, this method allows rigorous inference about the effective area by quantifying which possible curves are most consistent with the data.
A phase field model for segregation and precipitation induced by irradiation in alloys
Badillo, A.; Bellon, P.; Averback, R. S.
2015-04-01
A phase field model is introduced to model the evolution of multicomponent alloys under irradiation, including radiation-induced segregation and precipitation. The thermodynamic and kinetic components of this model are derived using a mean-field model. The mobility coefficient and the contribution of chemical heterogeneity to free energy are rescaled by the cell size used in the phase field model, yielding microstructural evolutions that are independent of the cell size. A new treatment is proposed for point defect clusters, using a mixed discrete-continuous approach to capture the stochastic character of defect cluster production in displacement cascades, while retaining the efficient modeling of the fate of these clusters using diffusion equations. The model is tested on unary and binary alloy systems using two-dimensional simulations. In a unary system, the evolution of point defects under irradiation is studied in the presence of defect clusters, either pre-existing ones or those created by irradiation, and compared with rate theory calculations. Binary alloys with zero and positive heats of mixing are then studied to investigate the effect of point defect clustering on radiation-induced segregation and precipitation in undersaturated solid solutions. Lastly, irradiation conditions and alloy parameters leading to irradiation-induced homogeneous precipitation are investigated. The results are discussed in the context of experimental results reported for Ni-Si and Al-Zn undersaturated solid solutions subjected to irradiation.
A phase field model for segregation and precipitation induced by irradiation in alloys
International Nuclear Information System (INIS)
Badillo, A; Bellon, P; Averback, R S
2015-01-01
A phase field model is introduced to model the evolution of multicomponent alloys under irradiation, including radiation-induced segregation and precipitation. The thermodynamic and kinetic components of this model are derived using a mean-field model. The mobility coefficient and the contribution of chemical heterogeneity to free energy are rescaled by the cell size used in the phase field model, yielding microstructural evolutions that are independent of the cell size. A new treatment is proposed for point defect clusters, using a mixed discrete-continuous approach to capture the stochastic character of defect cluster production in displacement cascades, while retaining the efficient modeling of the fate of these clusters using diffusion equations. The model is tested on unary and binary alloy systems using two-dimensional simulations. In a unary system, the evolution of point defects under irradiation is studied in the presence of defect clusters, either pre-existing ones or those created by irradiation, and compared with rate theory calculations. Binary alloys with zero and positive heats of mixing are then studied to investigate the effect of point defect clustering on radiation-induced segregation and precipitation in undersaturated solid solutions. Lastly, irradiation conditions and alloy parameters leading to irradiation-induced homogeneous precipitation are investigated. The results are discussed in the context of experimental results reported for Ni–Si and Al–Zn undersaturated solid solutions subjected to irradiation. (paper)
Directory of Open Access Journals (Sweden)
Huiguo Chen
2017-01-01
Full Text Available Based on the Kanai-Tajimi power spectrum filtering method proposed by Du Xiuli et al., a genetic algorithm and a quadratic optimization identification technique are employed to improve the bimodal time-varying modified Kanai-Tajimi power spectral model and the parameter identification method proposed by Vlachos et al. Additionally, a method for modeling time-varying power spectrum parameters for ground motion is proposed. The 8244 Orion and Chi-Chi earthquake accelerograms are selected as examples for time-varying power spectral model parameter identification and ground motion simulations to verify the feasibility and effectiveness of the improved bimodal time-varying modified Kanai-Tajimi power spectral model. The results of this study provide important references for designing ground motion inputs for seismic analyses of major engineering structures.
Al-Baarri, A. N.; Legowo, A. M.; Widayat
2018-01-01
D-glucose has been understood to provide the various effect on the reactivity in Maillard reaction resulting in the changes in physical performance of food product. Therefore this research was done to analyse physical appearance of Maillard reaction product made of D-glucose and methionine as a model system. The changes in browning value and spectral analysis model system were determined. The glucose-methionine model system was produced through the heating treatment at 50°C and RH 70% for 24 hours. The data were collected for every three hour using spectrophotometer. As result, browning value was elevated with the increase of heating time and remarkably high if compare to the D-glucose only. Furthermore, the spectral analysis showed that methionine turned the pattern of peak appearance. As conclusion, methionine raised the browning value and changed the pattern of spectral analysis in Maillard reaction model system.
International Nuclear Information System (INIS)
Pham, Binh T.; Hawkes, Grant L.; Einerson, Jeffrey J.
2014-01-01
As part of the High Temperature Reactors (HTR) R and D program, a series of irradiation tests, designated as Advanced Gas-cooled Reactor (AGR), have been defined to support development and qualification of fuel design, fabrication process, and fuel performance under normal operation and accident conditions. The AGR tests employ fuel compacts placed in a graphite cylinder shrouded by a steel capsule and instrumented with thermocouples (TC) embedded in graphite blocks enabling temperature control. While not possible to obtain by direct measurements in the tests, crucial fuel conditions (e.g., temperature, neutron fast fluence, and burnup) are calculated using core physics and thermal modeling codes. This paper is focused on AGR test fuel temperature predicted by the ABAQUS code's finite element-based thermal models. The work follows up on a previous study, in which several statistical analysis methods were adapted, implemented in the NGNP Data Management and Analysis System (NDMAS), and applied for qualification of AGR-1 thermocouple data. Abnormal trends in measured data revealed by the statistical analysis are traced to either measuring instrument deterioration or physical mechanisms in capsules that may have shifted the system thermal response. The main thrust of this work is to exploit the variety of data obtained in irradiation and post-irradiation examination (PIE) for assessment of modeling assumptions. As an example, the uneven reduction of the control gas gap in Capsule 5 found in the capsule metrology measurements in PIE helps identify mechanisms other than TC drift causing the decrease in TC readings. This suggests a more physics-based modification of the thermal model that leads to a better fit with experimental data, thus reducing model uncertainty and increasing confidence in the calculated fuel temperatures of the AGR-1 test
Energy Technology Data Exchange (ETDEWEB)
Pham, Binh T., E-mail: Binh.Pham@inl.gov [Human Factor, Controls and Statistics Department, Nuclear Science and Technology, Idaho National Laboratory, Idaho Falls, ID 83415 (United States); Hawkes, Grant L. [Thermal Science and Safety Analysis Department, Nuclear Science and Technology, Idaho National Laboratory, Idaho Falls, ID 83415 (United States); Einerson, Jeffrey J. [Human Factor, Controls and Statistics Department, Nuclear Science and Technology, Idaho National Laboratory, Idaho Falls, ID 83415 (United States)
2014-05-01
As part of the High Temperature Reactors (HTR) R and D program, a series of irradiation tests, designated as Advanced Gas-cooled Reactor (AGR), have been defined to support development and qualification of fuel design, fabrication process, and fuel performance under normal operation and accident conditions. The AGR tests employ fuel compacts placed in a graphite cylinder shrouded by a steel capsule and instrumented with thermocouples (TC) embedded in graphite blocks enabling temperature control. While not possible to obtain by direct measurements in the tests, crucial fuel conditions (e.g., temperature, neutron fast fluence, and burnup) are calculated using core physics and thermal modeling codes. This paper is focused on AGR test fuel temperature predicted by the ABAQUS code's finite element-based thermal models. The work follows up on a previous study, in which several statistical analysis methods were adapted, implemented in the NGNP Data Management and Analysis System (NDMAS), and applied for qualification of AGR-1 thermocouple data. Abnormal trends in measured data revealed by the statistical analysis are traced to either measuring instrument deterioration or physical mechanisms in capsules that may have shifted the system thermal response. The main thrust of this work is to exploit the variety of data obtained in irradiation and post-irradiation examination (PIE) for assessment of modeling assumptions. As an example, the uneven reduction of the control gas gap in Capsule 5 found in the capsule metrology measurements in PIE helps identify mechanisms other than TC drift causing the decrease in TC readings. This suggests a more physics-based modification of the thermal model that leads to a better fit with experimental data, thus reducing model uncertainty and increasing confidence in the calculated fuel temperatures of the AGR-1 test.
3D airborne EM modeling based on the spectral-element time-domain (SETD) method
Cao, X.; Yin, C.; Huang, X.; Liu, Y.; Zhang, B., Sr.; Cai, J.; Liu, L.
2017-12-01
In the field of 3D airborne electromagnetic (AEM) modeling, both finite-difference time-domain (FDTD) method and finite-element time-domain (FETD) method have limitations that FDTD method depends too much on the grids and time steps, while FETD requires large number of grids for complex structures. We propose a time-domain spectral-element (SETD) method based on GLL interpolation basis functions for spatial discretization and Backward Euler (BE) technique for time discretization. The spectral-element method is based on a weighted residual technique with polynomials as vector basis functions. It can contribute to an accurate result by increasing the order of polynomials and suppressing spurious solution. BE method is a stable tine discretization technique that has no limitation on time steps and can guarantee a higher accuracy during the iteration process. To minimize the non-zero number of sparse matrix and obtain a diagonal mass matrix, we apply the reduced order integral technique. A direct solver with its speed independent of the condition number is adopted for quickly solving the large-scale sparse linear equations system. To check the accuracy of our SETD algorithm, we compare our results with semi-analytical solutions for a three-layered earth model within the time lapse 10-6-10-2s for different physical meshes and SE orders. The results show that the relative errors for magnetic field B and magnetic induction are both around 3-5%. Further we calculate AEM responses for an AEM system over a 3D earth model in Figure 1. From numerical experiments for both 1D and 3D model, we draw the conclusions that: 1) SETD can deliver an accurate results for both dB/dt and B; 2) increasing SE order improves the modeling accuracy for early to middle time channels when the EM field diffuses fast so the high-order SE can model the detailed variation; 3) at very late time channels, increasing SE order has little improvement on modeling accuracy, but the time interval plays
Modelling the cosmic spectral energy distribution and extragalactic background light over all time
Andrews, S. K.; Driver, S. P.; Davies, L. J. M.; Lagos, C. d. P.; Robotham, A. S. G.
2018-02-01
We present a phenomological model of the cosmic spectral energy distribution (CSED) and the integrated galactic light (IGL) over all cosmic time. This model, based on an earlier model by Driver et al., attributes the cosmic star formation history (CSFH) to two processes - first, chaotic clump accretion and major mergers, resulting in the early-time formation of bulges and secondly, cold gas accretion, resulting in late-time disc formation. Under the assumption of a Universal Chabrier initial mass function, we combine the Bruzual & Charlot stellar libraries, the Charlot & Fall dust attenuation prescription and template spectra for emission by dust and active galactic nuclei to predict the CSED - pre- and post-dust attenuation - and the IGL throughout cosmic time. The phenomological model, as constructed, adopts a number of basic axioms and empirical results and has minimal free parameters. We compare the model output, as well as predictions from the semi-analytic model GALFORM to recent estimates of the CSED out to z = 1. By construction, our empirical model reproduces the full energy output of the Universe from the ultraviolet to the far-infrared extremely well. We use the model to derive predictions of the stellar and dust mass densities, again finding good agreement. We find that GALFORM predicts the CSED for z < 0.3 in good agreement with the observations. This agreement becomes increasingly poor towards z = 1, when the model CSED is ˜50 per cent fainter. The latter is consistent with the model underpredicting the CSFH. As a consequence, GALFORM predicts a ˜30 per cent fainter IGL.
Swelling analysis of austenitic stainless steels by means of ion irradiation and kinetic modeling
International Nuclear Information System (INIS)
Kohyama, Akira; Donomae, Takako
1999-03-01
The influences of irradiation environment on the swelling behavior of austenitic stainless steel has been studied, to aid understanding the origin of the difference in swelling response of PNC316 stainless steel in fuel-pin environment and in materials irradiation capsules, in terms of irradiation conditions, damage mechanism and material conditions. This work focused on the theoretical investigation of the influence of temperature variation on microstructural development of austenitic stainless steels during irradiation, using a kinetic rate theory model. A modeling and calculation on non-steady irradiation effects were first carried out. A fully dynamic model of point defect evolution and extended defect development, which accounts for cascade damage, was developed and successfully applied to simulate the interstitial loop evolution in low temperature regimes. The influence of cascade interstitial clustering on dislocation loop formation has also been assessed. The establishment of a basis for general assessment of non-steady irradiation effects in austenitic stainless steels was advanced. The developed model was applied to evaluate the influences of temperature variation in formerly carried out CMIR and FFTF/MFA-1 FBR irradiation experiments. The results suggested the gradual approach of microstructural features to equilibrium states in all the temperature variation conditions and no sign of anomalous behavior was noted. On the other hand, there is the influence of temperature variation on microstructural development under the neutron irradiation, like CMIR. So there are some possibilities of the work of mechanism which is not taken care on this model, for example the effect of the precipitate behavior which is sensitive to irradiation temperature. (author)
Absorbed dose modeled for a liquid circulating around a Co-60 irradiator
International Nuclear Information System (INIS)
Mangussi, J.
2013-01-01
A model for the distribution of the absorbed dose in a volume of liquid circulating into an active tank containing a Co-60 irradiator is presented. The absorbed dose, the stir process and the liquid recirculation into the active tank are modeled. The absorbed dose for different fractions of the volume is calculated. The necessary irradiation times for the achievement of the required absorbed dose are evaluated. (author)
Materials aging: first predictive modeling of iron under irradiation
International Nuclear Information System (INIS)
Anon.
2005-01-01
Researchers from the CEA-Bruyeres-le-Chatel have been able to quantitatively foresee for the very first time the evolution of irradiation defects inside a structural material. Their results, obtained with iron, will contribute to better understand the aging of the materials of today's nuclear power plants and of future nuclear systems. Short paper. (J.S.)
Towards realistic modelling of spectral line formation - lessons learnt from red giants
Lind, Karin
2015-08-01
Many decades of quantitative spectroscopic studies of red giants have revealed much about the formation histories and interlinks between the main components of the Galaxy and its satellites. Telescopes and instrumentation are now able to deliver high-resolution data of superb quality for large stellar samples and Galactic archaeology has entered a new era. At the same time, we have learnt how simplifying physical assumptions in the modelling of spectroscopic data can bias the interpretations, in particular one-dimensional homogeneity and local thermodynamic equilibrium (LTE). I will present lessons learnt so far from non-LTE spectral line formation in 3D radiation-hydrodynamic atmospheres of red giants, the smaller siblings of red supergiants.
Physics of Solar Prominences: I-Spectral Diagnostics and Non-LTE Modelling
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
Theoretical spectral properties of PAHs: towards a detailed model of their photophysics in the ISM
International Nuclear Information System (INIS)
Malloci, Giuliano; Mulas, Giacomo; Porceddu, Ignazio
2005-01-01
In the framework of density functional theory (DFT) we computed the spectral properties of a total of about 20 polycyclic aromatic hydrocarbons (PAHs) in different charge states. From our complete atlas of PAHs, ranging in size from naphthalene (C 10 H 8 ) to dicoronylene (C 48 H 20 ), we present here a sample of results concerning both ground-state and excited-state properties. Our theoretical results are in reasonable agreement with the available experimental data. This makes them particularly precious when the latter are not easily obtainable, as is often the case for the highly reactive radicals and ions of such species. In another paper (Mulas et al., same volume) we show that our theoretical results can be reliably used to model the behaviour of these molecules in astrophysical environments
Improved Frequency Fluctuation Model for Spectral Line Shape Calculations in Fusion Plasmas
International Nuclear Information System (INIS)
Ferri, S.; Calisti, A.; Mosse, C.; Talin, B.; Lisitsa, V.
2010-01-01
A very fast method to calculate spectral line shapes emitted by plasmas accounting for charge particle dynamics and effects of an external magnetic field is proposed. This method relies on a new formulation of the Frequency Fluctuation Model (FFM), which yields to an expression of the dynamic line profile as a functional of the static distribution function of frequencies. This highly efficient formalism, not limited to hydrogen-like systems, allows to calculate pure Stark and Stark-Zeeman line shapes for a wide range of density, temperature and magnetic field values, which is of importance in plasma physics and astrophysics. Various applications of this method are presented for conditions related to fusion plasmas.
Directory of Open Access Journals (Sweden)
Thomas E. Rosmond
2000-01-01
Full Text Available The Navy Operational Global Atmospheric Prediction System (NOGAPS includes a state-of-the-art spectral forecast model similar to models run at several major operational numerical weather prediction (NWP centers around the world. The model, developed by the Naval Research Laboratory (NRL in Monterey, California, has run operational at the Fleet Numerical Meteorological and Oceanographic Center (FNMOC since 1982, and most recently is being run on a Cray C90 in a multi-tasked configuration. Typically the multi-tasked code runs on 10 to 15 processors with overall parallel efficiency of about 90%. resolution is T159L30, but other operational and research applications run at significantly lower resolutions. A scalable NOGAPS forecast model has been developed by NRL in anticipation of a FNMOC C90 replacement in about 2001, as well as for current NOGAPS research requirements to run on DOD High-Performance Computing (HPC scalable systems. The model is designed to run with message passing (MPI. Model design criteria include bit reproducibility for different processor numbers and reasonably efficient performance on fully shared memory, distributed memory, and distributed shared memory systems for a wide range of model resolutions. Results for a wide range of processor numbers, model resolutions, and different vendor architectures are presented. Single node performance has been disappointing on RISC based systems, at least compared to vector processor performance. This is a common complaint, and will require careful re-examination of traditional numerical weather prediction (NWP model software design and data organization to fully exploit future scalable architectures.
Energy Technology Data Exchange (ETDEWEB)
Liu, Youshan, E-mail: ysliu@mail.iggcas.ac.cn [State Key Laboratory of Lithospheric Evolution, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing, 100029 (China); Teng, Jiwen, E-mail: jwteng@mail.iggcas.ac.cn [State Key Laboratory of Lithospheric Evolution, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing, 100029 (China); Xu, Tao, E-mail: xutao@mail.iggcas.ac.cn [State Key Laboratory of Lithospheric Evolution, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing, 100029 (China); CAS Center for Excellence in Tibetan Plateau Earth Sciences, Beijing, 100101 (China); Badal, José, E-mail: badal@unizar.es [Physics of the Earth, Sciences B, University of Zaragoza, Pedro Cerbuna 12, 50009 Zaragoza (Spain)
2017-05-01
The mass-lumped method avoids the cost of inverting the mass matrix and simultaneously maintains spatial accuracy by adopting additional interior integration points, known as cubature points. To date, such points are only known analytically in tensor domains, such as quadrilateral or hexahedral elements. Thus, the diagonal-mass-matrix spectral element method (SEM) in non-tensor domains always relies on numerically computed interpolation points or quadrature points. However, only the cubature points for degrees 1 to 6 are known, which is the reason that we have developed a p-norm-based optimization algorithm to obtain higher-order cubature points. In this way, we obtain and tabulate new cubature points with all positive integration weights for degrees 7 to 9. The dispersion analysis illustrates that the dispersion relation determined from the new optimized cubature points is comparable to that of the mass and stiffness matrices obtained by exact integration. Simultaneously, the Lebesgue constant for the new optimized cubature points indicates its surprisingly good interpolation properties. As a result, such points provide both good interpolation properties and integration accuracy. The Courant–Friedrichs–Lewy (CFL) numbers are tabulated for the conventional Fekete-based triangular spectral element (TSEM), the TSEM with exact integration, and the optimized cubature-based TSEM (OTSEM). A complementary study demonstrates the spectral convergence of the OTSEM. A numerical example conducted on a half-space model demonstrates that the OTSEM improves the accuracy by approximately one order of magnitude compared to the conventional Fekete-based TSEM. In particular, the accuracy of the 7th-order OTSEM is even higher than that of the 14th-order Fekete-based TSEM. Furthermore, the OTSEM produces a result that can compete in accuracy with the quadrilateral SEM (QSEM). The high accuracy of the OTSEM is also tested with a non-flat topography model. In terms of computational
Liu, Youshan; Teng, Jiwen; Xu, Tao; Badal, José
2017-05-01
The mass-lumped method avoids the cost of inverting the mass matrix and simultaneously maintains spatial accuracy by adopting additional interior integration points, known as cubature points. To date, such points are only known analytically in tensor domains, such as quadrilateral or hexahedral elements. Thus, the diagonal-mass-matrix spectral element method (SEM) in non-tensor domains always relies on numerically computed interpolation points or quadrature points. However, only the cubature points for degrees 1 to 6 are known, which is the reason that we have developed a p-norm-based optimization algorithm to obtain higher-order cubature points. In this way, we obtain and tabulate new cubature points with all positive integration weights for degrees 7 to 9. The dispersion analysis illustrates that the dispersion relation determined from the new optimized cubature points is comparable to that of the mass and stiffness matrices obtained by exact integration. Simultaneously, the Lebesgue constant for the new optimized cubature points indicates its surprisingly good interpolation properties. As a result, such points provide both good interpolation properties and integration accuracy. The Courant-Friedrichs-Lewy (CFL) numbers are tabulated for the conventional Fekete-based triangular spectral element (TSEM), the TSEM with exact integration, and the optimized cubature-based TSEM (OTSEM). A complementary study demonstrates the spectral convergence of the OTSEM. A numerical example conducted on a half-space model demonstrates that the OTSEM improves the accuracy by approximately one order of magnitude compared to the conventional Fekete-based TSEM. In particular, the accuracy of the 7th-order OTSEM is even higher than that of the 14th-order Fekete-based TSEM. Furthermore, the OTSEM produces a result that can compete in accuracy with the quadrilateral SEM (QSEM). The high accuracy of the OTSEM is also tested with a non-flat topography model. In terms of computational
International Nuclear Information System (INIS)
Liu, Youshan; Teng, Jiwen; Xu, Tao; Badal, José
2017-01-01
The mass-lumped method avoids the cost of inverting the mass matrix and simultaneously maintains spatial accuracy by adopting additional interior integration points, known as cubature points. To date, such points are only known analytically in tensor domains, such as quadrilateral or hexahedral elements. Thus, the diagonal-mass-matrix spectral element method (SEM) in non-tensor domains always relies on numerically computed interpolation points or quadrature points. However, only the cubature points for degrees 1 to 6 are known, which is the reason that we have developed a p-norm-based optimization algorithm to obtain higher-order cubature points. In this way, we obtain and tabulate new cubature points with all positive integration weights for degrees 7 to 9. The dispersion analysis illustrates that the dispersion relation determined from the new optimized cubature points is comparable to that of the mass and stiffness matrices obtained by exact integration. Simultaneously, the Lebesgue constant for the new optimized cubature points indicates its surprisingly good interpolation properties. As a result, such points provide both good interpolation properties and integration accuracy. The Courant–Friedrichs–Lewy (CFL) numbers are tabulated for the conventional Fekete-based triangular spectral element (TSEM), the TSEM with exact integration, and the optimized cubature-based TSEM (OTSEM). A complementary study demonstrates the spectral convergence of the OTSEM. A numerical example conducted on a half-space model demonstrates that the OTSEM improves the accuracy by approximately one order of magnitude compared to the conventional Fekete-based TSEM. In particular, the accuracy of the 7th-order OTSEM is even higher than that of the 14th-order Fekete-based TSEM. Furthermore, the OTSEM produces a result that can compete in accuracy with the quadrilateral SEM (QSEM). The high accuracy of the OTSEM is also tested with a non-flat topography model. In terms of computational
NOAA Climate Data Record (CDR) of Total Solar Irradiance (TSI), NRLTSI Version 2
National Oceanic and Atmospheric Administration, Department of Commerce — This Climate Data Record (CDR) contains total solar irradiance (TSI) as a function of time created with the Naval Research Laboratory model for spectral and total...
International Nuclear Information System (INIS)
Onimus, F.
2003-12-01
Zirconium alloys cladding tubes containing nuclear fuel of the Pressurized Water Reactors constitute the first safety barrier against the dissemination of radioactive elements. Thus, it is essential to predict the mechanical behavior of the material in-reactor conditions. This study aims, on the one hand, to identify and characterize the mechanisms of the plastic deformation of irradiated zirconium alloys and, on the other hand, to propose a micro-mechanical modeling based on these mechanisms. The experimental analysis shows that, for the irradiated material, the plastic deformation occurs by dislocation channeling. For transverse tensile test and internal pressure test this channeling occurs in the basal planes. However, for axial tensile test, the study revealed that the plastic deformation also occurs by channeling but in the prismatic and pyramidal planes. In addition, the study of the macroscopic mechanical behavior, compared to the deformation mechanisms observed by TEM, suggested that the internal stress is higher in the case of irradiated material than in the case of non-irradiated material, because of the very heterogeneous character of the plastic deformation. This analysis led to a coherent interpretation of the mechanical behavior of irradiated materials, in terms of deformation mechanisms. The mechanical behavior of irradiated materials was finally modeled by applying homogenization methods for heterogeneous materials. This model is able to reproduce adequately the mechanical behavior of the irradiated material, in agreement with the TEM observations. (author)
Kosmopoulos, Panagiotis G.; Kazadzis, Stelios; Taylor, Michael; Athanasopoulou, Eleni; Speyer, Orestis; Raptis, Panagiotis I.; Marinou, Eleni; Proestakis, Emmanouil; Solomos, Stavros; Gerasopoulos, Evangelos; Amiridis, Vassilis; Bais, Alkiviadis; Kontoes, Charalabos
2017-07-01
This study assesses the impact of dust on surface solar radiation focussing on an extreme dust event. For this purpose, we exploited the synergy of AERONET measurements and passive and active satellite remote sensing (MODIS and CALIPSO) observations, in conjunction with radiative transfer model (RTM) and chemical transport model (CTM) simulations and the 1-day forecasts from the Copernicus Atmosphere Monitoring Service (CAMS). The area of interest is the eastern Mediterranean where anomalously high aerosol loads were recorded between 30 January and 3 February 2015. The intensity of the event was extremely high, with aerosol optical depth (AOD) reaching 3.5, and optical/microphysical properties suggesting aged dust. RTM and CTM simulations were able to quantify the extent of dust impact on surface irradiances and reveal substantial reduction in solar energy exploitation capacity of PV and CSP installations under this high aerosol load. We found that such an extreme dust event can result in Global Horizontal Irradiance (GHI) attenuation by as much as 40-50 % and a much stronger Direct Normal Irradiance (DNI) decrease (80-90 %), while spectrally this attenuation is distributed to 37 % in the UV region, 33 % in the visible and around 30 % in the infrared. CAMS forecasts provided a reliable available energy assessment (accuracy within 10 % of that obtained from MODIS). Spatially, the dust plume resulted in a zonally averaged reduction of GHI and DNI of the order of 150 W m-2 in southern Greece, and a mean increase of 20 W m-2 in the northern Greece as a result of lower AOD values combined with local atmospheric processes. This analysis of a real-world scenario contributes to the understanding and quantification of the impact range of high aerosol loads on solar energy and the potential for forecasting power generation failures at sunshine-privileged locations where solar power plants exist, are under construction or are being planned.
Kim, Myung-Hee Y.; Cucinotta, Francis A.; Zeitlin, Cary; Hassler, Donald M.; Ehresmann, Bent; Rafkin, Scot C. R.; Wimmer-Schweingruber, Robert F.; Boettcher, Stephan; Boehm, Eckart; Guo, Jingnan;
2014-01-01
Detailed measurements of the energetic particle radiation environment on the surface of Mars have been made by the Radiation Assessment Detector (RAD) on the Curiosity rover since August 2012. RAD is a particle detector that measures the energy spectrum of charged particles (10 to approx. 200 MeV/u) and high energy neutrons (approx 8 to 200 MeV). The data obtained on the surface of Mars for 300 sols are compared to the simulation results using the Badhwar-O'Neill galactic cosmic ray (GCR) environment model and the high-charge and energy transport (HZETRN) code. For the nuclear interactions of primary GCR through Mars atmosphere and Curiosity rover, the quantum multiple scattering theory of nuclear fragmentation (QMSFRG) is used. For describing the daily column depth of atmosphere, daily atmospheric pressure measurements at Gale Crater by the MSL Rover Environmental Monitoring Station (REMS) are implemented into transport calculations. Particle flux at RAD after traversing varying depths of atmosphere depends on the slant angles, and the model accounts for shielding of the RAD "E" dosimetry detector by the rest of the instrument. Detailed comparisons between model predictions and spectral data of various particle types provide the validation of radiation transport models, and suggest that future radiation environments on Mars can be predicted accurately. These contributions lend support to the understanding of radiation health risks to astronauts for the planning of various mission scenarios
Twisted Spectral Triple for the Standard Model and Spontaneous Breaking of the Grand Symmetry
Energy Technology Data Exchange (ETDEWEB)
Devastato, Agostino, E-mail: agostino.devastato@na.infn.it; Martinetti, Pierre, E-mail: martinetti@dima.unige.it [Università di Napoli Federico II, Dipartimento di Fisica (Italy)
2017-03-15
Grand symmetry models in noncommutative geometry, characterized by a non-trivial action of functions on spinors, have been introduced to generate minimally (i.e. without adding new fermions) and in agreement with the first order condition an extra scalar field beyond the standard model, which both stabilizes the electroweak vacuum and makes the computation of the mass of the Higgs compatible with its experimental value. In this paper, we use a twist in the sense of Connes-Moscovici to cure a technical problem due to the non-trivial action on spinors, that is the appearance together with the extra scalar field of unbounded vectorial terms. The twist makes these terms bounded and - thanks to a twisted version of the first-order condition that we introduce here - also permits to understand the breaking to the standard model as a dynamical process induced by the spectral action, as conjectured in [24]. This is a spontaneous breaking from a pre-geometric Pati-Salam model to the almost-commutativegeometryofthestandardmodel,withtwoHiggs-likefields: scalar and vector.
International Nuclear Information System (INIS)
Farias, Ruben; Gonzalez, S.J.; Bellino, A.; Sztenjberg, M.; Pinto, J.; Thorp, Silvia I.; Gadan, M.; Pozzi, Emiliano; Schwint, Amanda E.; Heber, Elisa M.; Trivillin, V.A.; Zarza, Leandro G.; Estryk, Guillermo; Miller, M.; Bortolussi, S.; Soto, M.S.; Nigg, D.W.
2009-01-01
We present a simple computational model of the reactor RA-3 developed using Monte Carlo transport code MCNP. The model parameters are adjusted in order to reproduce experimental measured points in air and the source validation is performed in an acrylic phantom. Performance analysis is carried out using computational models of animal extracorporeal irradiation in liver and lung. Analysis is also performed inside a neutron shielded receptacle use for the irradiation of rats with a model of hepatic metastases.The computational model reproduces the experimental behavior in all the analyzed cases with a maximum difference of 10 percent. (author)
Bora, S. S.; Scherbaum, F.; Kuehn, N. M.; Stafford, P.; Edwards, B.
2014-12-01
In a probabilistic seismic hazard assessment (PSHA) framework, it still remains a challenge to adjust ground motion prediction equations (GMPEs) for application in different seismological environments. In this context, this study presents a complete framework for the development of a response spectral GMPE easily adjustable to different seismological conditions; and which does not suffer from the technical problems associated with the adjustment in response spectral domain. Essentially, the approach consists of an empirical FAS (Fourier Amplitude Spectrum) model and a duration model for ground motion which are combined within the random vibration theory (RVT) framework to obtain the full response spectral ordinates. Additionally, FAS corresponding to individual acceleration records are extrapolated beyond the frequency range defined by the data using the stochastic FAS model, obtained by inversion as described in Edwards & Faeh, (2013). To that end, an empirical model for a duration, which is tuned to optimize the fit between RVT based and observed response spectral ordinate, at each oscillator frequency is derived. Although, the main motive of the presented approach was to address the adjustability issues of response spectral GMPEs; comparison, of median predicted response spectra with the other regional models indicate that presented approach can also be used as a stand-alone model. Besides that, a significantly lower aleatory variability (σbrands it to a potentially viable alternative to the classical regression (on response spectral ordinates) based GMPEs for seismic hazard studies in the near future. The dataset used for the presented analysis is a subset of the recently compiled database RESORCE-2012 across Europe, Middle East and the Mediterranean region.
Predicting spectral and PAR light attenuation in Greenlandic coastal waters
DEFF Research Database (Denmark)
Murray, Ciarán; Markager, Stiig; Stedmon, Colin
(CDOM), phytoplankton pigments and inorganic particles. These differences are due in part to hydrography and to the sources of meltwater: respectively, fjord-terminating and land-terminating glaciers. We present a model to explain the variation in spectral and PAR irradiance in terms of the variation...
Modeling of irradiation embrittlement and annealing/recovery in pressure vessel steels
International Nuclear Information System (INIS)
Lott, R.G.; Freyer, P.D.
1996-01-01
The results of reactor pressure vessel (RPV) annealing studies are interpreted in light of the current understanding of radiation embrittlement phenomena in RPV steels. An extensive RPV irradiation embrittlement and annealing database has been compiled and the data reveal that the majority of annealing studies completed to date have employed test reactor irradiated weldments. Although test reactor and power reactor irradiations result in similar embrittlement trends, subtle differences between these two damage states can become important in the interpretation of annealing results. Microstructural studies of irradiated steels suggest that there are several different irradiation-induced microstructural features that contribute to embrittlement. The amount of annealing recovery and the post-anneal re-embrittlement behavior of a steel are determined by the annealing response of these microstructural defects. The active embrittlement mechanisms are determined largely by the irradiation temperature and the material composition. Interpretation and thorough understanding of annealing results require a model that considers the underlying physical mechanisms of embrittlement. This paper presents a framework for the construction of a physically based mechanistic model of irradiation embrittlement and annealing behavior
Establishment and application of rat model of acute β-irradiated skin injury
International Nuclear Information System (INIS)
Shen Guoliang; Lu Xing'an; Tang Jun; Wang Xiuzhen; Wu Shiliang; Tian Ye
2006-01-01
Objective: To establish an experimental rat model of acute β-irradiated skin injury and to study the effects of superoxide dismutase (SOD) on wound healing. Methods: Areas of buttock skin (20 mm x 40 mm) of 40 male SD rats were irradiated with 45 Gy/β-rays generated by linear accelerator, and then the forty rats were divided into two groups randomly: treatment group administrated with SOD (n=20) and control group administrated with normal saline (NS) (n=20). The wound healing time and rate were observed. The pathological changes were observed by light microscopy. The expressions of VEGF (vascular endothelial growth factor) and bFGF (basic fibroblast growth factor) were determined by SP immunohistochemical method. Results: The deep second-degree burns was observed following 45 Gy irradiation. The wound healing time in treatment group was shorter than that of the control group (P<0.05). Strongly positive (+ + +) expression of VEGF, bFGF in treatment group and positive (+ +) expression of VEGF, bFGF in the control group were observed 6 weeks, 7 weeks and 8 weeks after the irradiation, while only weakly positive (+) expressions of VEGF and bFGF in both groups 4 weeks, 5 weeks and 9 weeks after the irradiation. Conclusions: The wound model of acute β-irradiated skin injury in rat was established and used in study of the effect of medicine on wound healing. SOD can promote the wound healing of acute β-irradiated skin injury. (authors)
Comparison of six different models describing survival of mammalian cells after irradiation
International Nuclear Information System (INIS)
Sontag, W.
1990-01-01
Six different cell-survival models have been compared. All models are based on the similar assumption that irradiated cells are able to exist in one of three states. S A is the state of a totally repaired cell, in state S C the cell contains lethal lesions and in state S b the cell contains potentially lethal lesions i.e. those which either can be repaired or converted into lethal lesions. The differences between the six models lie in the different mathematical relationships between the three states. To test the six models, six different sets of experimental data were used which describe cell survival at different repair times after irradiation with sparsely ionizing irradiation. In order to compare the models, a goodness-of-fit function was used. The differences between the six models were tested by use of the nonparametric Mann-Whitney two sample test. Based on the 95% confidence limit, this required separation into three groups. (orig.)
A model for diffuse and global irradiation on horizontal surface
International Nuclear Information System (INIS)
Jain, P.C.
1984-01-01
The intensity of the direct radiation and the diffuse radiation at any time on a horizontal surface are each expressed as fractions of the intensity of the extraterrestrial radiation. Using these and assuming a random distribution of the bright sunshine hours and not too wide variations in the values of the transmission coefficients, a number of relations for estimating the global and the diffuse irradiation are derived. Two of the relations derived are already known empirically. The formulation lends more confidence in the use of the already empirically known relations providing them a theoretical basis, and affords more flexibility to the estimation techniques by supplying new equations. The study identifies three independent basic parameters and the constants appearing in the various equations as simple functions of these three basic parameters. Experimental data for the diffuse irradiation, the global irradiation and the bright sunshine duration for Macerata (Italy), Salisbury and Bulawayo (Zimbabwe) is found to show good correlation for the linear equations, and the nature and the interrelationships of the constants are found to be as predicted by the theory
A theoretical model of processes of irradiation of workers in uranium mines
International Nuclear Information System (INIS)
Zettwoog, Pierre.
1980-11-01
A quantity caled mine 'irradiativity', which is the ratio of collective dose to the production of uranium 'metal', is introduced. A distinction is made between irradiativity due to external exposure and that due to radon. A mathematical model to predict irradiativity has been developed using specific data from a mine: a) amount and distribution of work in areas of access and production; b) technology of ore extraction, especially the productivity of ore extraction, which is a basic parameter; c) protection technologies, especially the ventilation system; and d) geologic conditions. A numerical example is presented [fr
Modeling the natural UV irradiation and comparative UV measurements at Moussala BEO (BG)
Tyutyundzhiev, N.; Angelov, Ch; Lovchinov, K.; Nitchev, Hr; Petrov, M.; Arsov, T.
2018-03-01
Studies of and modeling the impact of natural UV irradiation on the human population are of significant importance for human activity and economics. The sharp increase of environmental problems – extraordinary temperature changes, solar irradiation abnormalities, icy rains – raises the question of developing novel means of assessing and predicting potential UV effects. In this paper, we discuss new UV irradiation modeling based on recent real-time measurements at Moussala Basic Environmental Observatory (BEO) on Moussala Peak (2925 m ASL) in Rila Mountain, Bulgaria, and highlight the development and initial validation of portable embedded devices for UV-A, UV-B monitoring using open-source software architecture, narrow bandpass UV sensors, and the popular Arduino controllers. Despite the high temporal resolution of the VIS and UV irradiation measurements, the results obtained reveal the need of new assumptions in order to minimize the discrepancy with available databases.
Characterization of atom clusters in irradiated pressure vessel steels and model alloys
International Nuclear Information System (INIS)
Auger, P.; Pareige, P.; Akamatsu, M.; Van Duysen, J.C.
1993-12-01
In order to characterize the microstructural evolution of the iron solid solution under irradiation, two pressure vessel steels irradiated in service conditions and, for comparison, low copper model alloys irradiated with neutrons and electrons have been studied. The characterization has been carried out mainly thanks to small angle neutron scattering and atom probe experiments. Both techniques lead to the conclusion that clusters develop with irradiations. In Fe-Cu model alloys, copper clusters are formed containing uncertain proportions of iron. In the low copper industrial steels, the feature is more complex. Solute atoms like Ni, Mn and Si, sometimes associated with Cu, segregate as ''clouds'' more or less condensed in the iron solid solution. These silicides, or at least Si, Ni, Mn association, may facilitate the copper segregation although the initial iron matrix contains a low copper concentration. (authors). 24 refs., 3 figs., 2 tabs
Model for the evolution of network dislocation density in irradiated metals
International Nuclear Information System (INIS)
Garner, F.A.; Wolfer, W.G.
1982-01-01
It is a well-known fact that the total dislocation density that evolves in irradiated metals is a strong function of irradiation temperature. The dislocation density comprises two components, however, and only one of these (Frank loops) retains its temperature dependence at high fluence. The network dislocation density approaches a saturation level which is relatively insensitive to starting microstructure, stress, irradiation temperature, displacement rate and helium level. The latter statement is supported in this paper by a review of published microstructural data. A model has been developed to explain the insensitivity to many variables of the saturation network dislocation density in irradiated metals. This model also explains how the rate of approach to saturation can be sensitive to displacement rate and temperature while the saturation level itself is not dependent on temperature
Directory of Open Access Journals (Sweden)
Hongshan Zhao
2012-05-01
Full Text Available Short-term solar irradiance forecasting (STSIF is of great significance for the optimal operation and power predication of grid-connected photovoltaic (PV plants. However, STSIF is very complex to handle due to the random and nonlinear characteristics of solar irradiance under changeable weather conditions. Artificial Neural Network (ANN is suitable for STSIF modeling and many research works on this topic are presented, but the conciseness and robustness of the existing models still need to be improved. After discussing the relation between weather variations and irradiance, the characteristics of the statistical feature parameters of irradiance under different weather conditions are figured out. A novel ANN model using statistical feature parameters (ANN-SFP for STSIF is proposed in this paper. The input vector is reconstructed with several statistical feature parameters of irradiance and ambient temperature. Thus sufficient information can be effectively extracted from relatively few inputs and the model complexity is reduced. The model structure is determined by cross-validation (CV, and the Levenberg-Marquardt algorithm (LMA is used for the network training. Simulations are carried out to validate and compare the proposed model with the conventional ANN model using historical data series (ANN-HDS, and the results indicated that the forecast accuracy is obviously improved under variable weather conditions.
Defect trap model of gas behaviour in UO2 fuel during irradiation
International Nuclear Information System (INIS)
Szuta, A.
2003-01-01
Fission gas behaviour is one of the central concern in the fuel design, performance and hypothetical accident analysis. The report 'Defect trap model of gas behaviour in UO 2 fuel during irradiation' is the worldwide literature review of problems studied, experimental results and solutions proposed in related topics. Some of them were described in details in the report chapters. They are: anomalies in the experimental results; fission gas retention in the UO 2 fuel; microstructure of the UO 2 fuel after irradiation; fission gas release models; defect trap model of fission gas behaviour; fission gas release from UO 2 single crystal during low temperature irradiation in terms of a defect trap model; analysis of dynamic release of fission gases from single crystal UO 2 during low temperature irradiation in terms of defect trap model; behaviour of fission gas products in single crystal UO 2 during intermediate temperature irradiation in terms of a defect trap model; modification of re-crystallization temperature of UO 2 in function of burnup and its impact on fission gas release; apparent diffusion coefficient; formation of nanostructures in UO 2 fuel at high burnup; applications of the defect trap model to the gas leaking fuel elements number assessment in the nuclear power station (VVER-PWR)
Development of a cloud model to generate high-frequency solar irradiance and power data
Energy Technology Data Exchange (ETDEWEB)
Brower, Michael C.; Beaucage, Philippe; Frank, Jaclyn D.; Freedman, Jeffrey M. [AWS Truepower, Albany, NY (United States); Vidal, Jose [AWS Truepower, Barcelona (Spain)
2012-07-01
This paper describes a new method to synthesize high-frequency ({proportional_to}2 second) solar irradiance and photovoltaic output data for grid integration studies. The method couples a numerical weather prediction model with a newly developed stochastic-kinematic cloud model. The coupled model is shown to match the mean profiles as well as ramping characteristics of measured data on Oahu, Hawaii. This model was used to synthesize 2 years of 2-second irradiance and PV data for over 800 MW of hypothetical utility-scale and residential rooftop sites for the Hawaii Solar Integration Study. (orig.)
Miguez-Macho, Gonzalo; Stenchikov, Georgiy L.; Robock, Alan
2004-07-01
It is well known that regional climate simulations are sensitive to the size and position of the domain chosen for calculations. Here we study the physical mechanisms of this sensitivity. We conducted simulations with the Regional Atmospheric Modeling System (RAMS) for June 2000 over North America at 50 km horizontal resolution using a 7500 km × 5400 km grid and NCEP/NCAR reanalysis as boundary conditions. The position of the domain was displaced in several directions, always maintaining the U.S. in the interior, out of the buffer zone along the lateral boundaries. Circulation biases developed a large scale structure, organized by the Rocky Mountains, resulting from a systematic shifting of the synoptic wave trains that crossed the domain. The distortion of the large-scale circulation was produced by interaction of the modeled flow with the lateral boundaries of the nested domain and varied when the position of the grid was altered. This changed the large-scale environment among the different simulations and translated into diverse conditions for the development of the mesoscale processes that produce most of precipitation for the Great Plains in the summer season. As a consequence, precipitation results varied, sometimes greatly, among the experiments with the different grid positions. To eliminate the dependence of results on the position of the domain, we used spectral nudging of waves longer than 2500 km above the boundary layer. Moisture was not nudged at any level. This constrained the synoptic scales to follow reanalysis while allowing the model to develop the small-scale dynamics responsible for the rainfall. Nudging of the large scales successfully eliminated the variation of precipitation results when the grid was moved. We suggest that this technique is necessary for all downscaling studies with regional models with domain sizes of a few thousand kilometers and larger embedded in global models.
A model system to give an insight into the behaviour of gold nanoparticles under ion irradiation
International Nuclear Information System (INIS)
Ramjauny, Y.
2010-01-01
Nano-composites fabricated with ion-based techniques have a number of attractive characteristics. However, the main and most crucial difficulty in obtaining commercial NPs-based devices is the inability to produce a suitable narrow size and spatial NP distributions. The objective of this thesis is twofold: i) to go further in the description of the behavior of the ion-driven NPs and ii) to overcome the limitations related to the ion-beam techniques providing a guideline methodology to rationalize the synthesis of NPs when ion-beams are used. Thus, a model system is fabricated. It consists of chemically synthesized metallic nanoparticles sandwiched between two silica layers. We show how the ion irradiation and the temperature can be used to tune the size distribution of the embedded NPs. Moreover, we show that when an initially large NPs size distribution is considered, the study of the growth kinetic of the NPs under irradiation can be problematic. Our model system is than used to investigate in detail the behavior of the NPs under irradiation. We show that the evolution of the precipitate phase under irradiation is successfully described by an Ostwald ripening mechanism in an open system limited by the diffusion. Moreover, the concentration threshold for nucleation as well as the surface tension and the gold diffusivity in silica under irradiation is estimated. Finally, direct and inverse Ostwald ripening processes under irradiation are systematically investigated and the existing theoretical models experimentally checked. (author)
International Nuclear Information System (INIS)
Massoud, J.P.; Bugat, St.; Marini, B.; Lidbury, D.; Van Dyck, St.; Debarberis, L.
2008-01-01
Full text of publication follows. In nuclear PWRs, materials undergo degradation due to severe irradiation conditions that may limit their operational life. Utilities operating these reactors must quantify the aging and the potential degradations of reactor pressure vessels and also of internal structures to ensure safe and reliable plant operation. The EURATOM 6. Framework Integrated Project PERFECT (Prediction of Irradiation Damage Effects in Reactor Components) addresses irradiation damage in RPV materials and components by multi-scale modelling. This state-of-the-art approach offers potential advantages over the conventional empirical methods used in current practice of nuclear plant lifetime management. Launched in January 2004, this 48-month project is focusing on two main components of nuclear power plants which are subject to irradiation damage: the ferritic steel reactor pressure vessel and the austenitic steel internals. This project is also an opportunity to integrate the fragmented research and experience that currently exists within Europe in the field of numerical simulation of radiation damage and creates the links with international organisations involved in similar projects throughout the world. Continuous progress in the physical understanding of the phenomena involved in irradiation damage and continuous progress in computer sciences make possible the development of multi-scale numerical tools able to simulate the effects of irradiation on materials microstructure. The consequences of irradiation on mechanical and corrosion properties of materials are also tentatively modelled using such multi-scale modelling. But it requires to develop different mechanistic models at different levels of physics and engineering and to extend the state of knowledge in several scientific fields. And the links between these different kinds of models are particularly delicate to deal with and need specific works. Practically the main objective of PERFECT is to build
Energy Technology Data Exchange (ETDEWEB)
Smirnova, Olga A. [Federal State Unitary Enterprise Research and Technical Center of Radiation-Chemical Safety and Hygiene, Moscow (Russian Federation); Akleyev, Alexander V. [Urals Research Center for Radiation Medicine (URCRM), Chelyabinsk (Russian Federation); Chelyabinsk State University, Chelyabinsk (Russian Federation); Dimov, Georgy P. [Urals Research Center for Radiation Medicine (URCRM), Chelyabinsk (Russian Federation)
2014-08-15
A biologically motivated dynamical model of the lymphocytopoietic system in irradiated humans is applied here to analyze the data obtained under hematological examinations of residents of Techa riverside villages. Those people were exposed to chronic irradiation with varying dose rates, due to the radioactive contamination of the river basin by the Mayak Production Association. Modeling studies revealed the relationship between the dynamics of the lymphocytopoietic system in the examined individuals and the variation of dose rate over the considered period of time. It is found that the developed model is capable of reproducing the decreased level of blood lymphocyte concentration observed during the period of maximum radiation exposure, the recovery processes in the system observed during the period of decreasing dose rate, as well as the enhanced mitotic activity of bone marrow precursor cells in this hematopoietic lineage observed during the entire period under consideration. Mechanisms of these effects of chronic irradiation on the human lymphocytopoietic system are elucidated based on the applied model. The results obtained demonstrate the efficiency of the developed model in the analysis, investigation, and prediction of effects of chronic irradiation with varying dose rate on the human lymphocytopoietic system. In particular, the developed model can be used for predicting any radiation injury of this vital system in people exposed to chronic irradiation due to environmental radiological events, such as anthropogenic radiation accidents or radiological terroristic attacks. (orig.)
Effects of Gamma irradiation on uronic acid sugars as cell wall polysaccharide model systems
International Nuclear Information System (INIS)
Irawati, Zubaidah; Pilnik, W.
2001-01-01
Irradiation is an alternative preservation method with can be utilized to extend the self-life of agricultural products by eliminating number of insects, and decreasing microbial growth effectively. Cell wall polysaccharides which mainly consist of pectic substances, hemicelluloses and cellulose play a major role on the immediate fruits. their degradation mechanism can be elucidates by studying their degradation products resulting from the irradiated cell wall or cell wall components. Isolated apple pectin and alginates as different in solid state by gamma irradiation at 15-30 kGy under two different humidities. The parameters observed were viscosity, β-elimination in the ester groups of pectin, and distribution of molecular weight. Irradiation with the doses of 15-30 kGy could reduce the viscosity of pectin and alginates, while irradiation did not cause β-elimination in the ester groups of pectin as confirmed by titration and ion exchange chromatography methods. The formation of 4,5-unsaturated uronosyl residues as a product of cleavage of the pectin backbone via- β-elimination was not found in irradiated pectin as confirmed by thio barbiture acid (TBA) test. High Performance Size Exclusion Chromatography (HPSEC) analysis for the irradiated polysaccharide model systems revealed that the average number of molecular weight showed a decrease by increasing radiation dose. Storage condition in two different relative humidities affected significantly the degree of polymerization of pectin and alginates in solid state
International Nuclear Information System (INIS)
Rodriguez Diana Marcela; Hernandez Orlando; Kammer Andreas
2009-01-01
The aim of this research is to apply spectral correlation, local favorability indexes and Poisson's theorem as numerical methods for data processing and interpretation of potential field data associated with structural features; these techniques are applied to theoretical and real gravity and magnetic data of the Soapaga fault, located in the Boyaca Department, in the eastern Andean Mountains. Theoretical data of the Soapaga fault was obtained by forward modeling of geological and structural sections. Real data of the Soapaga fault included compiled gravity data and acquired magnetic data along four profiles oriented perpendicular to the fault. As a result, the geometry of the fault and its structural characteristics were obtained by interactive forward and inverse modeling. This methodology allows highlighting anomaly trends associated with density and magnetic susceptibility contrast that occur along the Soapaga fault zone. Additionally, this work provides a quantitative approach to establish the relationship between gravity and magnetic anomalies, supported by a rigorous mathematical methodology rather than isolated data interpretation to better understand the gravity and magnetic signatures of outcropping and hidden structural features.
Merino, G. G.; Jones, D.; Stooksbury, D. E.; Hubbard, K. G.
2001-06-01
In this paper, linear and spherical semivariogram models were determined for use in kriging hourly and daily solar irradiation for every season of the year. The data used to generate the models were from 18 weather stations in western Nebraska. The models generated were tested using cross validation. The performance of the spherical and linear semivariogram models were compared with each other and also with the semivariogram models based on the best fit to the sample semivariogram of a particular day or hour. There were no significant differences in the performance of the three models. This result and the comparable errors produced by the models in kriging indicated that the linear and spherical models could be used to perform kriging at any hour and day of the year without deriving an individual semivariogram model for that day or hour.The seasonal mean absolute errors associated with kriging, within the network, when using the spherical or the linear semivariograms models were between 10% and 13% of the mean irradiation for daily irradiation and between 12% and 20% for hourly irradiation. These errors represent an improvement of 1%-2% when compared with replacing data at a given site with the data of the nearest weather station.
Energy Technology Data Exchange (ETDEWEB)
Onimus, F
2003-12-01
Zirconium alloys cladding tubes containing nuclear fuel of the Pressurized Water Reactors constitute the first safety barrier against the dissemination of radioactive elements. Thus, it is essential to predict the mechanical behavior of the material in-reactor conditions. This study aims, on the one hand, to identify and characterize the mechanisms of the plastic deformation of irradiated zirconium alloys and, on the other hand, to propose a micro-mechanical modeling based on these mechanisms. The experimental analysis shows that, for the irradiated material, the plastic deformation occurs by dislocation channeling. For transverse tensile test and internal pressure test this channeling occurs in the basal planes. However, for axial tensile test, the study revealed that the plastic deformation also occurs by channeling but in the prismatic and pyramidal planes. In addition, the study of the macroscopic mechanical behavior, compared to the deformation mechanisms observed by TEM, suggested that the internal stress is higher in the case of irradiated material than in the case of non-irradiated material, because of the very heterogeneous character of the plastic deformation. This analysis led to a coherent interpretation of the mechanical behavior of irradiated materials, in terms of deformation mechanisms. The mechanical behavior of irradiated materials was finally modeled by applying homogenization methods for heterogeneous materials. This model is able to reproduce adequately the mechanical behavior of the irradiated material, in agreement with the TEM observations. (author)
Modeling of radiation-induced charge trapping in MOS devices under ionizing irradiation
Energy Technology Data Exchange (ETDEWEB)
Petukhov, M. A., E-mail: m.a.petukhov@gmail.com; Ryazanov, A. I. [National Research Center Kurchatov Institute (Russian Federation)
2016-12-15
The numerical model of the radiation-induced charge trapping process in the oxide layer of a MOS device under ionizing irradiation is developed; the model includes carrier transport, hole capture by traps in different states, recombination of free electrons and trapped holes, kinetics of hydrogen ions which can be accumulated in the material during transistor manufacture, and accumulation and charging of interface states. Modeling of n-channel MOSFET behavior under 1 MeV photon irradiation is performed. The obtained dose dependences of the threshold voltage shift and its contributions from trapped holes and interface states are in good agreement with experimental data.
Model animal experiments on UV-c irradiation of blood and isolated cell populations
International Nuclear Information System (INIS)
Repke, H.; Scherf, H.P.; Wiesner, S.
1984-01-01
The cellular and molecular basis of the therapeutically used effect of reinjected ultraviolet (UVC) irradiated blood is unknown. First approaches to that problem were made in this study by aid of model experiments. Neither the spontaneous degranulation nor the antigen-induced histamine release from rat connective tissue mast cells (in vivo) was influenced by the injection (i.v.) of UV-irradiated blood or blood lymphocytes. By comparison of the effect of UV light on blood lymphocytes (number of dead cells, strength of chemoluminescence) after irradiation of the isolated cells and the unfractionated blood, respectively, it was shown that the strong light absorption within the blood sample prevents damage or functional alterations of the blood lymphocytes. The compound 48/80 - induced histamine release from rat peritoneal mast cells can be completely inhibited by UV irradiation (0.6 mJ/cm 2 ) without increasing the spontaneous histamine release. (author)
Modeling of cavity swelling-induced embrittlement in irradiated austenitic stainless steels
International Nuclear Information System (INIS)
Han, X.
2012-01-01
During long-time neutron irradiation occurred in Pressurized Water Reactors (PWRs), significant changes of the mechanical behavior of materials used in reactor core internals (made of 300 series austenitic stainless steels) are observed, including irradiation induced hardening and softening, loss of ductility and toughness. So far, much effect has been made to identify radiation effects on material microstructure evolution (dislocations, Frank loops, cavities, segregation, etc.). The irradiation-induced cavity swelling, considered as a potential factor limiting the reactor lifetime, could change the mechanical properties of materials (plasticity, toughness, etc.), even lead to a structure distortion because of the dimensional modifications between different components. The principal aim of the present PhD work is to study qualitatively the influence of cavity swelling on the mechanical behaviors of irradiated materials. A micromechanical constitutive model based on dislocation and irradiation defect (Frank loops) density evolution has been developed and implemented into ZeBuLoN and Cast3M finite element codes to adapt the large deformation framework. 3D FE analysis is performed to compute the mechanical properties of a polycrystalline aggregate. Furthermore, homogenization technique is applied to develop a Gurson-type model. Unit cell simulations are used to study the mechanical behavior of porous single crystals, by accounting for various effects of stress triaxiality, of void volume fraction and of crystallographic orientation, in order to study void effect on the irradiated material plasticity and roughness at polycrystalline scale. (author) [fr
Planetary-Scale Inertio Gravity Waves in the Numerical Spectral Model
Mayr, H. G.; Mengel, J. R.; Talaat, E. R.; Porter, H. S.
2004-01-01
In the polar region of the upper mesosphere, horizontal wind oscillations have been observed with periods around 10 hours. Waves with such a period are generated in our Numerical Spectral Model (NSM), and they are identified as planetary-scale inertio gravity waves (IGW). These IGWs have periods between 9 and 11 hours and appear above 60 km in the zonal mean (m = 0), as well as in zonal wavenumbers m = 1 to 4. The waves can propagate eastward and westward and have vertical wavelengths around 25 km. The amplitudes in the wind field are typically between 10 and 20 m/s and can reach 30 m/s in the westward propagating component for m = 1 at the poles. In the temperature perturbations, the wave amplitudes above 100 km are typically 5 K and as large as 10 K for m = 0 at the poles. The IGWs are intermittent but reveal systematic seasonal variations, with the largest amplitudes occurring generally in late winter and spring. In the NSM, the IGW are generated like the planetary waves (PW). They are produced apparently by the instabilities that arise in the zonal mean circulation. Relative to the PWs, however, the IGWs propagate zonally with much larger velocities, such that they are not affected much by interactions with the background zonal winds. Since the IGWs can propagate through the mesosphere without much interaction, except for viscous dissipation, one should then expect that they reach the thermosphere with significant and measurable amplitudes.
International Nuclear Information System (INIS)
Kulmala, J.; Rantanen, V.; Turku Univ.; Pekkola-Heino, K.; Turku Univ.; Tuominen, J.; Grenman, R.; Turku Univ.
1995-01-01
Radiation experiments with cells in single cell suspension in test tubes and on 96-well plates were carried out and compared. The cells originated from cell lines established from carcinomas of the floor of the mouth and from endometrical carcinoma. Two irradiation models were constructed. Both models allowed the absorbed doses to the cells to be administered with a high accuracy in both experimental settings (better than 5.0%). These irradiation models were compared on cancer cell lines with dissimilar inherent radiation sensitivity and histologic type (UM-SCC-1 resistant, UM-SCC-14A sensitive, and UT-EC-2B highly sensitive); various radiation doses were used. The fractions of surviving cells as a function of radiation dose were compared: there was no significant difference between cells irradiated in test tubes and cells irradiated in 96-well plates. Thus, if the absorbed doses in cells suspended in a tube and in a plate were the same, the survival was similar regardless of the type of irradiation model. (orig.)
Stability of void lattices under irradiation: a kinetic model
International Nuclear Information System (INIS)
Benoist, P.; Martin, G.
1975-01-01
Voids are imbedded in a homogeneous medium where point defects are uniformly created and annihilated. As shown by a perturbation calculation, the proportion of the defects which are lost on the cavities goes through a maximum, when the voids are arranged on a translation lattice. If a void is displaced from its lattice site, its growth rate becomes anisotropic and is larger in the direction of the vacant site. The relative efficiency of BCC versus FCC void lattices for the capture of point defects is shown to depend on the relaxation length of the point defects in the surrounding medium. It is shown that the rate of energy dissipation in the crystal under irradiation is maximum when the voids are ordered on the appropriate lattice
Stability of void lattices under irradiation: a kinetic model
International Nuclear Information System (INIS)
Benoist, P.; Martin, G.
1975-01-01
Voids are imbedded in a homogeneous medium where point defects are uniformly created and annihilated. As shown by a perturbation calculation, the proportion of the defects which are lost on the cavities goes through a maximum, when the voids are arranged on a translation lattice. If a void is displaced from its lattice site, its growth the rate becomes anisotropic and is larger in the direction of the vacant site. The relative efficiency of BCC versus FCC void lattices for the capture of point defects is shown to depend on the relaxation length of the point defects in the surrounding medium. It is shown that the rate of energy dissipation in the crystal under irradiation is maximum when the voids are ordered on the appropriate lattice [fr
Efficient Hybrid-Spectral Model for Fully Nonlinear Numerical Wave Tank
DEFF Research Database (Denmark)
Christiansen, Torben; Bingham, Harry B.; Engsig-Karup, Allan Peter
2013-01-01
A new hybrid-spectral solution strategy is proposed for the simulation of the fully nonlinear free surface equations based on potential flow theory. A Fourier collocation method is adopted horisontally for the discretization of the free surface equations. This is combined with a modal Chebyshev Tau...... method in the vertical for the discretization of the Laplace equation in the fluid domain, which yields a sparse and spectrally accurate Dirichletto-Neumann operator. The Laplace problem is solved with an efficient Defect Correction method preconditioned with a spectral discretization of the linearised...... wave problem, ensuring fast convergence and optimal scaling with the problem size. Preliminary results for very nonlinear waves show expected convergence rates and a clear advantage of using spectral schemes....
Li, Wen-bing; Yao, Lin-tao; Liu, Mu-hua; Huang, Lin; Yao, Ming-yin; Chen, Tian-bing; He, Xiu-wen; Yang, Ping; Hu, Hui-qin; Nie, Jiang-hui
2015-05-01
Cu in navel orange was detected rapidly by laser-induced breakdown spectroscopy (LIBS) combined with partial least squares (PLS) for quantitative analysis, then the effect on the detection accuracy of the model with different spectral data ptetreatment methods was explored. Spectral data for the 52 Gannan navel orange samples were pretreated by different data smoothing, mean centralized and standard normal variable transform. Then 319~338 nm wavelength section containing characteristic spectral lines of Cu was selected to build PLS models, the main evaluation indexes of models such as regression coefficient (r), root mean square error of cross validation (RMSECV) and the root mean square error of prediction (RMSEP) were compared and analyzed. Three indicators of PLS model after 13 points smoothing and processing of the mean center were found reaching 0. 992 8, 3. 43 and 3. 4 respectively, the average relative error of prediction model is only 5. 55%, and in one word, the quality of calibration and prediction of this model are the best results. The results show that selecting the appropriate data pre-processing method, the prediction accuracy of PLS quantitative model of fruits and vegetables detected by LIBS can be improved effectively, providing a new method for fast and accurate detection of fruits and vegetables by LIBS.
Light Curve Simulation Using Spacecraft CAD Models and Empirical Material Spectral BRDFS
Willison, A.; Bedard, D.
This paper presents a Matlab-based light curve simulation software package that uses computer-aided design (CAD) models of spacecraft and the spectral bidirectional reflectance distribution function (sBRDF) of their homogenous surface materials. It represents the overall optical reflectance of objects as a sBRDF, a spectrometric quantity, obtainable during an optical ground truth experiment. The broadband bidirectional reflectance distribution function (BRDF), the basis of a broadband light curve, is produced by integrating the sBRDF over the optical wavelength range. Colour-filtered BRDFs, the basis of colour-filtered light curves, are produced by first multiplying the sBRDF by colour filters, and integrating the products. The software package's validity is established through comparison of simulated reflectance spectra and broadband light curves with those measured of the CanX-1 Engineering Model (EM) nanosatellite, collected during an optical ground truth experiment. It is currently being extended to simulate light curves of spacecraft in Earth orbit, using spacecraft Two-Line-Element (TLE) sets, yaw/pitch/roll angles, and observer coordinates. Measured light curves of the NEOSSat spacecraft will be used to validate simulated quantities. The sBRDF was chosen to represent material reflectance as it is spectrometric and a function of illumination and observation geometry. Homogeneous material sBRDFs were obtained using a goniospectrometer for a range of illumination and observation geometries, collected in a controlled environment. The materials analyzed include aluminum alloy, two types of triple-junction photovoltaic (TJPV) cell, white paint, and multi-layer insulation (MLI). Interpolation and extrapolation methods were used to determine the sBRDF for all possible illumination and observation geometries not measured in the laboratory, resulting in empirical look-up tables. These look-up tables are referenced when calculating the overall sBRDF of objects, where
Energy Technology Data Exchange (ETDEWEB)
El Ammouri, F; Plessier, R; Till, M; Marie, B; Djavdan, E [Air Liquide Centre de Recherche Claude Delorme, 78 - Jouy-en-Josas (France)
1997-12-31
Coupled reactive fluid dynamics and radiation calculations are performed in air and oxy-fuel furnaces using two gas radiative property models. The first one is the weighted sum of gray gases model (WSGG) and the second one is the correlated-k (CK) method which is a spectral model based on the cumulative distribution function of the absorption coefficient inside a narrow band. The WSGG model, generally used in industrial configurations, is less time consuming than the CK model. However it is found that it over-predicts radiative fluxes by about 12 % in industrial furnaces. (authors) 27 refs.
Energy Technology Data Exchange (ETDEWEB)
El Ammouri, F.; Plessier, R.; Till, M.; Marie, B.; Djavdan, E. [Air Liquide Centre de Recherche Claude Delorme, 78 - Jouy-en-Josas (France)
1996-12-31
Coupled reactive fluid dynamics and radiation calculations are performed in air and oxy-fuel furnaces using two gas radiative property models. The first one is the weighted sum of gray gases model (WSGG) and the second one is the correlated-k (CK) method which is a spectral model based on the cumulative distribution function of the absorption coefficient inside a narrow band. The WSGG model, generally used in industrial configurations, is less time consuming than the CK model. However it is found that it over-predicts radiative fluxes by about 12 % in industrial furnaces. (authors) 27 refs.
Transplantation of ES cells to Parkinson model rat irradiated with carbon ion beam
International Nuclear Information System (INIS)
Inaji, Motoki; Okauchi, Takashi; Nagai, Yuji; Nojima, Kumie
2003-01-01
The present study was designed to make better Parkinson model animal and evaluate the transplantation treatment with ES cell. In the first year, we irradiated left striatum of adult rats with charged carbon particles (290 MeV/nucleon, 5 mm spread-out Bragg peak, 100 Gy) for purpose of making Parkinson model rats. At 4, 8, 12 weeks after the irradiation, we performed the rotation test to methamphetamine and the autoradiography on dopamine D2 receptor and transporter using 11 C-raclopride and 11 C-PE2I to measure the effects of the irradiation. As a result, the number of rotation increased and the distributions of dopamine D2 receptor and transporter in the striatum decreased during the time after the irradiation. These results suggested that the secondary neural damage due to the vascular degeneration caused the progressive destruction of dopamine system. To make more stable Parkinson model rats, we need to use smaller collimator and develop the accurate stereotactic irradiation system in the further research. (author)
Evaluation of Clear Sky Models for Satellite-Based Irradiance Estimates
Energy Technology Data Exchange (ETDEWEB)
Sengupta, Manajit [National Renewable Energy Lab. (NREL), Golden, CO (United States); Gotseff, Peter [National Renewable Energy Lab. (NREL), Golden, CO (United States)
2013-12-01
This report describes an intercomparison of three popular broadband clear sky solar irradiance model results with measured data, as well as satellite-based model clear sky results compared to measured clear sky data. The authors conclude that one of the popular clear sky models (the Bird clear sky model developed by Richard Bird and Roland Hulstrom) could serve as a more accurate replacement for current satellite-model clear sky estimations. Additionally, the analysis of the model results with respect to model input parameters indicates that rather than climatological, annual, or monthly mean input data, higher-time-resolution input parameters improve the general clear sky model performance.
ATR neutron spectral characterization
Energy Technology Data Exchange (ETDEWEB)
Rogers, J.W.; Anderl, R.A.
1995-11-01
The Advanced Test Reactor (ATR) at INEL provides intense neutron fields for irradiation-effects testing of reactor material samples, for production of radionuclides used in industrial and medical applications, and for scientific research. Characterization of the neutron environments in the irradiation locations of the ATR has been done by means of neutronics calculations and by means of neutron dosimetry based on the use of neutron activation monitors that are placed in the various irradiation locations. The primary purpose of this report is to present the results of an extensive characterization of several ATR irradiation locations based on neutron dosimetry measurements and on least-squares-adjustment analyses that utilize both neutron dosimetry measurements and neutronics calculations. This report builds upon the previous publications, especially the reference 4 paper. Section 2 provides a brief description of the ATR and it tabulates neutron spectral information for typical irradiation locations, as derived from the more historical neutron dosimetry measurements. Relevant details that pertain to the multigroup neutron spectral characterization are covered in section 3. This discussion includes a presentation on the dosimeter irradiation and analyses and a development of the least-squares adjustment methodology, along with a summary of the results of these analyses. Spectrum-averaged cross sections for neutron monitoring and for displacement-damage prediction in Fe, Cr, and Ni are given in section 4. In addition, section4 includes estimates of damage generation rates for these materials in selected ATR irradiation locations. In section 5, the authors present a brief discussion of the most significant conclusions of this work and comment on its relevance to the present ATR core configuration. Finally, detailed numerical and graphical results for the spectrum-characterization analyses in each irradiation location are provided in the Appendix.
International Nuclear Information System (INIS)
Auger, P.; Pareige, P.; Akamatsu, M.; Van Duysen, J.C.
1993-01-01
In order to characterize the microstructural evolution of iron solid solution under irradiation, two pressure vessel steels irradiated in service conditions, and, for comparison, low copper model alloys irradiated with neutrons and electrons, have been studied through small angle neutron scattering and atom probe experiments. In Fe-Cu model alloys, copper clusters are formed containing uncertain proportions of iron. In the low copper industrial steels, the feature is more complex; solute atoms such as Ni, Mn and Si, sometimes associated with Cu, segregate as ''clouds'' more or less condensed in the iron solid solution. These silicides, or at least Si, Ni, Mn association, may facilitate the copper segregation although the initial iron matrix contains a low copper concentration. (authors). 24 refs., 3 figs., 2 tabs
Transplantation of ES cells to Parkinson model rat irradiated with carbon ion beam
International Nuclear Information System (INIS)
Inaji, Motoki; Okauchi, Takashi; Nagai, Yuji; Nojima, Kumie; Suhara, Tetsuya
2004-01-01
The present study was designed to make a new Parkinson disease model using carbon ion beam. In this year, we irradiated right middle forebrain bundle of adult rats with charged carbon particles (290 MeV/nucleon, Mono peak, 150 Gy) and damaged right dopaminergic neurons pathway. To irradiate precisely, rats were set in the stereotactic frame with ear bars which was developed in this year. In 4 weeks after the irradiation, we performed methamphetamine induced rotation test and the autoradiography measurement on dopamine transporter using [ 11 C]PE2I to assess degeneration of dopaminergic neurons in caudate putamen (Cpu). As a result, ipsilateral rotation was observed and the distributions of dopamine transporter in the striatum decreased significantly. These results are similar to those of 6-OHDA lesioned rats, and indicate validity of this model. (author)
Energy Technology Data Exchange (ETDEWEB)
Auger, P; Pareige, P [Rouen Univ., 76 - Mont-Saint-Aignan (France); Akamatsu, M; Van Duysen, J C [Electricite de France (EDF), 77 - Ecuelles (France)
1994-12-31
In order to characterize the microstructural evolution of iron solid solution under irradiation, two pressure vessel steels irradiated in service conditions, and, for comparison, low copper model alloys irradiated with neutrons and electrons, have been studied through small angle neutron scattering and atom probe experiments. In Fe-Cu model alloys, copper clusters are formed containing uncertain proportions of iron. In the low copper industrial steels, the feature is more complex; solute atoms such as Ni, Mn and Si, sometimes associated with Cu, segregate as ``clouds`` more or less condensed in the iron solid solution. These silicides, or at least Si, Ni, Mn association, may facilitate the copper segregation although the initial iron matrix contains a low copper concentration. (authors). 24 refs., 3 figs., 2 tabs.
Swartz, M.; Allkofer, Y.; Bortoletto, D.; Cremaldi, L.; Cucciarelli, S.; Dorokhov, A.; Hoermann, C.; Kim, D.; Konecki, M.; Kotlinski, D.; Prokofiev, Kirill; Regenfus, Christian; Rohe, T.; Sanders, D.A.; Son, S.; Speer, T.
2006-01-01
We show that doubly peaked electric fields are necessary to describe grazing-angle charge collection measurements of irradiated silicon pixel sensors. A model of irradiated silicon based upon two defect levels with opposite charge states and the trapping of charge carriers can be tuned to produce a good description of the measured charge collection profiles in the fluence range from 0.5x10^{14} Neq/cm^2 to 5.9x10^{14} Neq/cm^2. The model correctly predicts the variation in the profiles as the temperature is changed from -10C to -25C. The measured charge collection profiles are inconsistent with the linearly-varying electric fields predicted by the usual description based upon a uniform effective doping density. This observation calls into question the practice of using effective doping densities to characterize irradiated silicon.
Energy Technology Data Exchange (ETDEWEB)
Cristaldi, Alice; Ermolli, Ilaria, E-mail: alice.cristaldi@oaroma.inaf.it [INAF Osservatorio Astronomico di Roma, via Frascati 33, Monte Porzio Catone, I-00078 (Italy)
2017-06-01
Present-day semi-empirical models of solar irradiance (SI) variations reconstruct SI changes measured on timescales greater than a day by using spectra computed in one dimensional atmosphere models (1D models), which are representative of various solar surface features. Various recent studies have pointed out, however, that the spectra synthesized in 1D models do not reflect the radiative emission of the inhomogenous atmosphere revealed by high-resolution solar observations. We aimed to derive observation-based atmospheres from such observations and test their accuracy for SI estimates. We analyzed spectropolarimetric data of the Fe i 630 nm line pair in photospheric regions that are representative of the granular quiet-Sun pattern (QS) and of small- and large-scale magnetic features, both bright and dark with respect to the QS. The data were taken on 2011 August 6, with the CRisp Imaging Spectropolarimeter at the Swedish Solar Telescope, under excellent seeing conditions. We derived atmosphere models of the observed regions from data inversion with the SIR code. We studied the sensitivity of results to spatial resolution and temporal evolution, and discuss the obtained atmospheres with respect to several 1D models. The atmospheres derived from our study agree well with most of the 1D models we compare our results with, both qualitatively and quantitatively (within 10%), except for pore regions. Spectral synthesis computations of the atmosphere obtained from the QS observations return an SI between 400 and 2400 nm that agrees, on average, within 2.2% with standard reference measurements, and within −0.14% with the SI computed on the QS atmosphere employed by the most advanced semi-empirical model of SI variations.
Energy Technology Data Exchange (ETDEWEB)
Sathyanarayana Rao, Mayuri; Subrahmanyan, Ravi; Shankar, N Udaya [Raman Research Institute, C V Raman Avenue, Sadashivanagar, Bangalore 560080 (India); Chluba, Jens, E-mail: mayuris@rri.res.in [Jodrell Bank Centre for Astrophysics, University of Manchester, Oxford Road, M13 9PL (United Kingdom)
2017-05-01
Cosmic baryon evolution during the Cosmic Dawn and Reionization results in redshifted 21-cm spectral distortions in the cosmic microwave background (CMB). These encode information about the nature and timing of first sources over redshifts 30–6 and appear at meter wavelengths as a tiny CMB distortion along with the Galactic and extragalactic radio sky, which is orders of magnitude brighter. Therefore, detection requires precise methods to model foregrounds. We present a method of foreground fitting using maximally smooth (MS) functions. We demonstrate the usefulness of MS functions over traditionally used polynomials to separate foregrounds from the Epoch of Reionization (EoR) signal. We also examine the level of spectral complexity in plausible foregrounds using GMOSS, a physically motivated model of the radio sky, and find that they are indeed smooth and can be modeled by MS functions to levels sufficient to discern the vanilla model of the EoR signal. We show that MS functions are loss resistant and robustly preserve EoR signal strength and turning points in the residuals. Finally, we demonstrate that in using a well-calibrated spectral radiometer and modeling foregrounds with MS functions, the global EoR signal can be detected with a Bayesian approach with 90% confidence in 10 minutes’ integration.
NMR experiments on ion permeation in irradiated model membranes
International Nuclear Information System (INIS)
Sprinz, H.; Winkler, E.; Schaefer, H.
1981-01-01
In aqueous solutions of egg-lecithin vesicles treated with ultrasonics the 1 H NMR parameters line width, area, and chemical shift of the signal of the (CH 3 ) 3 N + group were determined as a function of the gamma dose (0 ... 12 kGy). Using europium and the line shape analysis, it has been possible to calculate these parameters for the inside as well as for the outside lipid layer. Increasing 60 Co radiation dose leads to linear increases of the line widths, which are significantly more rapid for the outer than for the inner layer. From that it can be concluded that the outside lipid layer has been more damaged by irradiation. The asymmetry may be the consequence of a radiation effect induced by the radicals of water radiolysis. From the temporal changes of the NMR parameters information can be obtained about the radiation effect on transport processes in the vesicles. Beginning at a threshold (approx. 5 kGy) the permeation of Eu +++ ions to the (CH 3 ) 3 N + head groups, previously not accessible, increases significantly. (author)
Biochemical and hematological indicators in model of total body irradiation
International Nuclear Information System (INIS)
Dubner, D; Gisone, P.; Perez, M.R.; Barboza, M.; Luchetta, P.; Longoni, H.; Sorrentino, M.; Robison, A.
1998-01-01
With the purpose of evaluating the applicability of several biological indicators in accidental overexposures a study was carried out in 20 patients undergoing therapeutical total body irradiation (TBI). The following parameters were evaluated: a) Oxidative stress indicators: erythrocyte superoxide dismutase (SOD) and catalase activity (CAT), lipo peroxyde levels (TBARS) and total plasma antioxidant activity (TAA). b) Haematological indicators: reticulocyte maturity index (RMI) and charges in lymphocyte subpopulations. Non significant changes in SOD and CAT activity were observed. Significant higher TBARS levels were found in patients with unfavorable post-BTM course without any significant correlation with TAA. RMI decreased early and dropped to zero in most of the patients and rose several days prior to reticulocyte, neutrophils and platelets counts. A significant decrease in absolute counts of all lymphocyte subpopulations was observed during TBI, particularly for B lymphocytes. A subpopulation of natural killer (NK) cells (CD16+/ CD 56 +) showed a relative higher radioresistance. Cytotoxic activity was significantly decreased after TBI. These data suggest that TBARS could provide an useful evolutive indicator in accidental over exposure d patients and RMI is an early indicator of bone marrow recovery after radioinduced aplasia. The implications of the different radiosensitivities within the NK subsets remains unanswered. (author) [es
Continental Spatio-temporal Data Analysis with Linear Spectral Mixture Model using FOSS
Kumar, U.; Nemani, R. R.; Ganguly, S.; Milesi, C.; Raja, K. S.; Wang, W.; Votava, P.; Michaelis, A.
2015-12-01
This work demonstrates the development and implementation of a Fully Constrained Least Squares (FCLS) unmixing model developed in C++ programming language with OpenCV package and boost C++ libraries in the NASA Earth Exchange (NEX). Visualization of the results is supported by GRASS GIS and statistical analysis is carried in R in a Linux system environment. FCLS was first tested on computer simulated data with Gaussian noise of various signal-to-noise ratio, and Landsat data of an agricultural scenario and an urban environment using a set of global endmembers of substrate (soils, sediments, rocks, and non-photosynthetic vegetation), vegetation that includes green photosynthetic plants and dark objects which encompasses absorptive substrate materials, clear water, deep shadows, etc. For the agricultural scenario, a spectrally diverse collection of 11 scenes of Level 1 terrain corrected, cloud free Landsat-5 TM data of Fresno, California, USA were unmixed and the results were validated with the corresponding ground data. To study an urbanized landscape, a clear sky Landsat-5 TM data were unmixed and validated with coincident World View-2 abundance maps (of 2 m spatial resolution) for an area of San Francisco, California, USA. The results were evaluated using descriptive statistics, correlation coefficient, RMSE, probability of success, boxplot and bivariate distribution function. Finally, FCLS was used for sub-pixel land cover analysis of the monthly WELD (Wen-enabled Landsat data) repository from 2008 to 2011 of North America. The abundance maps in conjunction with DMSP-OLS nighttime lights data were used to extract the urban land cover features and analyze their spatial-temporal growth.
Continental Spatio-Temporal Data Analysis with Linear Spectral Mixture Model Using FOSS
Kumar, Uttam; Nemani, Ramakrishna; Ganguly, Sangram; Milesi, Cristina; Raja, Kumar; Wang, Weile; Votava, Petr; Michaelis, Andrew
2015-01-01
This work demonstrates the development and implementation of a Fully Constrained Least Squares (FCLS) unmixing model developed in C++ programming language with OpenCV package and boost C++ libraries in the NASA Earth Exchange (NEX). Visualization of the results is supported by GRASS GIS and statistical analysis is carried in R in a Linux system environment. FCLS was first tested on computer simulated data with Gaussian noise of various signal-to-noise ratio, and Landsat data of an agricultural scenario and an urban environment using a set of global end members of substrate (soils, sediments, rocks, and non-photosynthetic vegetation), vegetation that includes green photosynthetic plants and dark objects which encompasses absorptive substrate materials, clear water, deep shadows, etc. For the agricultural scenario, a spectrally diverse collection of 11 scenes of Level 1 terrain corrected, cloud free Landsat-5 TM data of Fresno, California, USA were unmixed and the results were validated with the corresponding ground data. To study an urbanized landscape, a clear sky Landsat-5 TM data were unmixed and validated with coincident World View-2 abundance maps (of 2 m spatial resolution) for an area of San Francisco, California, USA. The results were evaluated using descriptive statistics, correlation coefficient, RMSE, probability of success, boxplot and bivariate distribution function. Finally, FCLS was used for sub-pixel land cover analysis of the monthly WELD (Wen-enabled Landsat data) repository from 2008 to 2011 of North America. The abundance maps in conjunction with DMSP-OLS nighttime lights data were used to extract the urban land cover features and analyze their spatial-temporal growth.
Directory of Open Access Journals (Sweden)
Martin Hofmann
2017-09-01
Full Text Available We analyze the output of various state-of-the-art irradiance models for photovoltaic systems. The models include two sun position algorithms, three types of input data time series, nine diffuse fraction models and five transposition models (for tilted surfaces, resulting in 270 different model chains for the photovoltaic (PV system simulation. These model chains are applied to 30 locations worldwide and three different module tracking types, totaling in 24,300 simulations. We show that the simulated PV yearly energy output varies between −5% and +8% for fixed mounted PV modules and between −26% and +14% for modules with two-axis tracking. Model quality varies strongly between locations; sun position algorithms have negligible influence on the simulation results; diffuse fraction models add a lot of variability; and transposition models feature the strongest influence on the simulation results. To highlight the importance of irradiance with high temporal resolution, we present an analysis of the influence of input temporal resolution and simulation models on the inverter clipping losses at varying PV system sizing factors for Lindenberg, Germany. Irradiance in one-minute resolution is essential for accurately calculating inverter clipping losses.
Huang, Xin; Yin, Chang-Chun; Cao, Xiao-Yue; Liu, Yun-He; Zhang, Bo; Cai, Jing
2017-09-01
The airborne electromagnetic (AEM) method has a high sampling rate and survey flexibility. However, traditional numerical modeling approaches must use high-resolution physical grids to guarantee modeling accuracy, especially for complex geological structures such as anisotropic earth. This can lead to huge computational costs. To solve this problem, we propose a spectral-element (SE) method for 3D AEM anisotropic modeling, which combines the advantages of spectral and finite-element methods. Thus, the SE method has accuracy as high as that of the spectral method and the ability to model complex geology inherited from the finite-element method. The SE method can improve the modeling accuracy within discrete grids and reduce the dependence of modeling results on the grids. This helps achieve high-accuracy anisotropic AEM modeling. We first introduced a rotating tensor of anisotropic conductivity to Maxwell's equations and described the electrical field via SE basis functions based on GLL interpolation polynomials. We used the Galerkin weighted residual method to establish the linear equation system for the SE method, and we took a vertical magnetic dipole as the transmission source for our AEM modeling. We then applied fourth-order SE calculations with coarse physical grids to check the accuracy of our modeling results against a 1D semi-analytical solution for an anisotropic half-space model and verified the high accuracy of the SE. Moreover, we conducted AEM modeling for different anisotropic 3D abnormal bodies using two physical grid scales and three orders of SE to obtain the convergence conditions for different anisotropic abnormal bodies. Finally, we studied the identification of anisotropy for single anisotropic abnormal bodies, anisotropic surrounding rock, and single anisotropic abnormal body embedded in an anisotropic surrounding rock. This approach will play a key role in the inversion and interpretation of AEM data collected in regions with anisotropic
Phobos MRO/CRISM visible and near-infrared (0.5-2.5 μm) spectral modeling
Pajola, Maurizio; Roush, Ted; Dalle Ore, Cristina; Marzo, Giuseppe A.; Simioni, Emanuele
2018-05-01
This paper focuses on the spectral modeling of the surface of Phobos in the wavelength range between 0.5 and 2.5 μm. We exploit the Phobos Mars Reconnaissance Orbiter/Compact Reconnaissance Imaging Spectrometer for Mars (MRO/CRISM) dataset and extend the study area presented by Fraeman et al. (2012) including spectra from nearly the entire surface observed. Without a priori selection of surface locations we use the unsupervised K-means partitioning algorithm developed by Marzo et al. (2006) to investigate the spectral variability across Phobos surface. The statistical partitioning identifies seven clusters. We investigate the compositional information contained within the average spectra of four clusters using the radiative transfer model of Shkuratov et al. (1999). We use optical constants of Tagish Lake meteorite (TL), from Roush (2003), and pyroxene glass (PM80), from Jaeger et al. (1994) and Dorschner et al. (1995), as previously suggested by Pajola et al. (2013) as inputs for the calculations. The model results show good agreement in slope when compared to the averages of the CRISM spectral clusters. In particular, the best fitting model of the cluster with the steepest spectral slope yields relative abundances that are equal to those of Pajola et al. (2013), i.e. 20% PM80 and 80% TL, but grain sizes that are 12 μm smaller for PM80 and 4 μm smaller for TL (the grain sizes are 11 μm for PM80 and 20 μm for TL in Pajola et al. (2013), respectively). This modest discrepancy may arise from the fact that the areas observed by CRISM and those analyzed in Pajola et al. (2013) are on opposite locations on Phobos and are characterized by different morphological and weathering settings. Instead, as the clusters spectral slopes decrease, the best fits obtained show trends related to both relative abundance and grain size that is not observed for the cluster with the steepest spectral slope. With a decrease in slope there is general increase of relative percentage of
A stochastic post-processing method for solar irradiance forecasts derived from NWPs models
Lara-Fanego, V.; Pozo-Vazquez, D.; Ruiz-Arias, J. A.; Santos-Alamillos, F. J.; Tovar-Pescador, J.
2010-09-01
Solar irradiance forecast is an important area of research for the future of the solar-based renewable energy systems. Numerical Weather Prediction models (NWPs) have proved to be a valuable tool for solar irradiance forecasting with lead time up to a few days. Nevertheless, these models show low skill in forecasting the solar irradiance under cloudy conditions. Additionally, climatic (averaged over seasons) aerosol loading are usually considered in these models, leading to considerable errors for the Direct Normal Irradiance (DNI) forecasts during high aerosols load conditions. In this work we propose a post-processing method for the Global Irradiance (GHI) and DNI forecasts derived from NWPs. Particularly, the methods is based on the use of Autoregressive Moving Average with External Explanatory Variables (ARMAX) stochastic models. These models are applied to the residuals of the NWPs forecasts and uses as external variables the measured cloud fraction and aerosol loading of the day previous to the forecast. The method is evaluated for a set one-moth length three-days-ahead forecast of the GHI and DNI, obtained based on the WRF mesoscale atmospheric model, for several locations in Andalusia (Southern Spain). The Cloud fraction is derived from MSG satellite estimates and the aerosol loading from the MODIS platform estimates. Both sources of information are readily available at the time of the forecast. Results showed a considerable improvement of the forecasting skill of the WRF model using the proposed post-processing method. Particularly, relative improvement (in terms of the RMSE) for the DNI during summer is about 20%. A similar value is obtained for the GHI during the winter.
Comparison of Modelled and Measured Tilted Solar Irradiance for Photovoltaic Applications
Directory of Open Access Journals (Sweden)
Riyad Mubarak
2017-10-01
Full Text Available This work assesses the performance of five transposition models that estimate the global and diffuse solar irradiance on tilted planes based on the global horizontal irradiance. The modelled tilted irradiance values are compared to measured one-minute values from pyranometers and silicon sensors tilted at different angles at Hannover (Germany and NREL (Golden, CO, USA. It can be recognized that the deviations of the model of Liu and Jordan, Klucher and Perez from the measurements increases as the tilt angle increases and as the sensors are oriented away from the south direction, where they receive lower direct radiation than south-oriented surfaces. Accordingly, the vertical E, W and N planes show the highest deviation. Best results are found by the models from Hay and Davies and Reindl, when horizontal pyranometer measurements and a constant albedo value of 0.2 are used. The relative root mean squared difference (rRMSD of the anisotropic models does not exceed 11% for south orientation and low inclination angles (β = 10–60°, but reaches up to 28.9% at vertical planes. For sunny locations such as Golden, the Perez model provides the best estimates of global tilted irradiance for south-facing surfaces. The relative mean absolute difference (rMAD of the Perez model at NREL ranges from 4.2% for 40° tilt to 8.7% for 90° tilt angle, when horizontal pyranometer measurements and a measured albedo value are used; the use of measured albedo values instead of a constant value of 0.2 leads to a reduction of the deviation to 3.9% and 6.0%, respectively. The use of higher albedo values leads to a significant increase of rMAD. We also investigated the uncertainty resulting from using horizontal pyranometer measurements, in combination with constant albedo values, to estimate the incident irradiance on tilted photovoltaic (PV modules. We found that these uncertainties are small or negligible.
Model of cancer growth affected by irradiation. Effect of fluctuating intensity of the dose
International Nuclear Information System (INIS)
Gudowska-Nowak, E.
1984-01-01
The behaviour of a biological model system which describes the growth of a cancer cell population in the presence of external irradiation is studied. The effect of randomly fluctuating source of radiation is analysed and its influence on cancer cell extinction is presented. The main stress is put on the biological significance of random fluctuations which seem to favour rejection of a tumor. (author)
Tailored vs Black-Box Models for Forecasting Hourly Average Solar Irradiance
Czech Academy of Sciences Publication Activity Database
Brabec, Marek; Paulescu, M.; Badescu, V.
2015-01-01
Roč. 111, January (2015), s. 320-331 ISSN 0038-092X R&D Projects: GA MŠk LD12009 Grant - others:European Cooperation in Science and Technology(XE) COST ES1002 Institutional support: RVO:67985807 Keywords : solar irradiance * forecasting * tilored statistical models Subject RIV: BB - Applied Statistics, Operational Research Impact factor: 3.685, year: 2015
International Nuclear Information System (INIS)
Christien, F.; Barbu, A.
2005-01-01
A model based on the cluster dynamics approach was proposed in [A. Hardouin Duparc, C. Moingeon, N. Smetniansky-de-Grande, A. Barbu, J. Nucl. Mater. 302 (2002) 143] to describe point defect agglomeration in metals under irradiation. This model is restricted to materials where point defect diffusion is isotropic and is thus not applicable to anisotropic metals such as zirconium. Following the approach proposed by Woo [C.H. Woo, J. Nucl. Mater. 159 (1988) 237], we extended in this work the model to the case where self-interstitial atoms (SIA) diffusion is anisotropic. The model was then applied to the loop microstructure evolution of a zirconium thin foil irradiated with electrons in a high-voltage microscope. First, the inputs were validated by comparing the numerical results with Hellio et al. experimental results [C. Hellio, C.H. de Novion, L. Boulanger, J. Nucl. Mater. 159 (1988) 368]. Further calculations were made to evidence the effect of the thin foil orientation on the dislocation loop microstructure under irradiation. The result is that it is possible to reproduce for certain orientations the 'unexpected' vacancy loop growth experimentally observed in electron-irradiated zirconium [M. Griffiths, M.H. Loretto, R.E. Sallmann, J. Nucl. Mater. 115 (1983) 313; J. Nucl. Mater. 115 (1983) 323; Philos. Mag. A 49 (1984) 613]. This effect is directly linked to SIA diffusion anisotropy
Modeling and simulation of heat distribution in human skin caused by laser irradiation
Luan, Y.; Dams, S.D.
2009-01-01
Study of light-based skin rejuvenation needs prospective insights of mechanism of laser tissue interaction. A well-built model plays a key role in predicting temperature distribution in human skin exposed to laser irradiation. Therefore, it not only provides guidance for in vitro experiment, but
Directory of Open Access Journals (Sweden)
Andrey V. Tokar
2014-03-01
Full Text Available The structure and spectral properties for molecular complexes, which formed by added monomer form of pentaplast as well as N-phenylbenzamide with some species of intermolecular interaction in system «penton-terlon» have been investigated at ab initio level of theory. It is shown, that the main contribution in total energy of molecules have included by dispersion forces, which realized between Chlorine atom of CH2Cl-group and Hydrogen atoms of benzene rings with amide fragment. The proposed theoretical models are validated in reflection of spectral and energetic characteristics of investigating system. Finally, the results of calculations are in good agreement with that data, which have been obtained for such type modeling previously.
Franta, Daniel; Nečas, David; Giglia, Angelo; Franta, Pavel; Ohlídal, Ivan
2017-11-01
Optical characterization of magnesium fluoride thin films is performed in a wide spectral range from far infrared to extreme ultraviolet (0.01-45 eV) utilizing the universal dispersion model. Two film defects, i.e. random roughness of the upper boundaries and defect transition layer at lower boundary are taken into account. An extension of universal dispersion model consisting in expressing the excitonic contributions as linear combinations of Gaussian and truncated Lorentzian terms is introduced. The spectral dependencies of the optical constants are presented in a graphical form and by the complete set of dispersion parameters that allows generating tabulated optical constants with required range and step using a simple utility in the newAD2 software package.
Energy Technology Data Exchange (ETDEWEB)
Hoversten, Erik A. [Johns Hopkins Univ., Baltimore, MD (United States)
2007-10-01
This thesis centers on the use of spectral modeling techniques on data from the Sloan Digital Sky Survey (SDSS) to gain new insights into current questions in galaxy evolution. The SDSS provides a large, uniform, high quality data set which can be exploited in a number of ways. One avenue pursued here is to use the large sample size to measure precisely the mean properties of galaxies of increasingly narrow parameter ranges. The other route taken is to look for rare objects which open up for exploration new areas in galaxy parameter space. The crux of this thesis is revisiting the classical Kennicutt method for inferring the stellar initial mass function (IMF) from the integrated light properties of galaxies. A large data set (~ 10^{5} galaxies) from the SDSS DR4 is combined with more in-depth modeling and quantitative statistical analysis to search for systematic IMF variations as a function of galaxy luminosity. Galaxy Hα equivalent widths are compared to a broadband color index to constrain the IMF. It is found that for the sample as a whole the best fitting IMF power law slope above 0.5 M_{⊙} is Γ = 1.5 ± 0.1 with the error dominated by systematics. Galaxies brighter than around M_{r,0.1} = -20 (including galaxies like the Milky Way which has M_{r,0.1} ~ -21) are well fit by a universal Γ ~ 1.4 IMF, similar to the classical Salpeter slope, and smooth, exponential star formation histories (SFH). Fainter galaxies prefer steeper IMFs and the quality of the fits reveal that for these galaxies a universal IMF with smooth SFHs is actually a poor assumption. Related projects are also pursued. A targeted photometric search is conducted for strongly lensed Lyman break galaxies (LBG) similar to MS1512-cB58. The evolution of the photometric selection technique is described as are the results of spectroscopic follow-up of the best targets. The serendipitous discovery of two interesting blue compact dwarf galaxies is reported. These
Modeling injected interstitial effects on void swelling in self-ion irradiation experiments
Energy Technology Data Exchange (ETDEWEB)
Short, M.P., E-mail: hereiam@mit.edu [Dept. of Nuclear Science and Engineering, Massachusetts Institute of Technology (United States); Gaston, D.R. [Idaho National Laboratory (United States); Jin, M. [Dept. of Nuclear Science and Engineering, Massachusetts Institute of Technology (United States); Shao, L. [Dept. of Nuclear Engineering, Texas A& M University (United States); Garner, F.A. [Radiation Effects Consulting, LLC (United States)
2016-04-01
Heavy ion irradiations at high dose rates are often used to simulate slow and expensive neutron irradiation experiments. However, many differences in the resultant modes of damage arise due to unique aspects of heavy ion irradiation. One such difference was recently shown in pure iron to manifest itself as a double peak in void swelling, with both peaks located away from the region of highest displacement damage. In other cases involving a variety of ferritic alloys there is often only a single peak in swelling vs. depth that is located very near the ion-incident surface. We show that these behaviors arise due to a combination of two separate effects: 1) suppression of void swelling due to injected interstitials, and 2) preferential sinking of interstitials to the ion-incident surface, which are very sensitive to the irradiation temperature and displacement rate. Care should therefore be used in collection and interpretation of data from the depth range outside the Bragg peak of ion irradiation experiments, as it is shown to be more complex than previously envisioned. - Highlights: • A model of the spatially dependent point defect kinetics equations with injected interstitials has been implemented. • The results predict a double peak in the void nucleation rate, helping to explain a recent experiment. • The double peak is predicted to be evident within a narrow (+/− 30 °C) temperature window for self-irradiation of pure iron. • The ballistic damage profile may not match the resultant void swelling profile from ion irradiation experiments.
International Nuclear Information System (INIS)
Nomura, T.; Makino, N.; Oda, T.; Suzuki, I.; Sakai, K
2004-01-01
The effects of low-dose rate gamma-irradiation were investigated on model mice for type II diabetes mellitus, C57BL/KsJ-db/db. The mice develop the type II diabetes by 10 weeks of age due to obesity and are characterized by hyperinsulinemia. Female 10-week old mice, a group of 12 mice, were irradiated at 0.65 mGy/hr from 137-Cs (370 GBq). The urine glucose levels of all of the mice were strongly positive at the beginning of the irradiation. In the irradiated group, the decrease in the glucose level was observed in 3 mice. Such recovery from the diabetes was never observed in 12 mice of non-irradiated control group. There is no systematic difference in the change of body weight, food assumption, and amount of drinking water, between the irradiated group and the non-irradiated group or between the recovered mice and the non-recovered mice. The survival was better in the irradiated group: the surviving fraction at the age of 90 weeks was 75% in the irradiated group, while 40% in the non-irradiated. Marked difference was also observed in the appearance of the coat hair, skin, and tail; better condition was kept in the irradiated group. In the irradiated mice mortality was delayed and the healthy appearance was prolonged in the irradiated mice by about 20 ? 30 weeks compared with the non-irradiated mice. These results suggest that the low-dose irradiation modified the condition of the diabetic mice, which lead not only to the recovery of the diabetes, but also to the suppression of the aging process. (Author)
Directory of Open Access Journals (Sweden)
Yuki Yagasaki
Full Text Available We examined the effects of gamma knife (GK irradiation on injured nerves using a rat partial sciatic nerve ligation (PSL model. GK irradiation was performed at one week after ligation and nerve preparations were made three weeks after ligation. GK irradiation is known to induce immune responses such as glial cell activation in the central nervous system. Thus, we determined the effects of GK irradiation on macrophages using immunoblot and histochemical analyses. Expression of Iba-1 protein, a macrophage marker, was further increased in GK-treated injured nerves as compared with non-irradiated injured nerves. Immunohistochemical study of Iba-1 in GK-irradiated injured sciatic nerves demonstrated Iba-1 positive macrophage accumulation to be enhanced in areas distal to the ligation point. In the same area, myelin debris was also more efficiently removed by GK-irradiation. Myelin debris clearance by macrophages is thought to contribute to a permissive environment for axon growth. In the immunoblot study, GK irradiation significantly increased expressions of βIII-tubulin protein and myelin protein zero, which are markers of axon regeneration and re-myelination, respectively. Toluidine blue staining revealed the re-myelinated fiber diameter to be larger at proximal sites and that the re-myelinated fiber number was increased at distal sites in GK-irradiated injured nerves as compared with non-irradiated injured nerves. These results suggest that GK irradiation of injured nerves facilitates regeneration and re-myelination. In a behavior study, early alleviation of allodynia was observed with GK irradiation in PSL rats. When GK-induced alleviation of allodynia was initially detected, the expression of glial cell line-derived neurotrophic factor (GDNF, a potent analgesic factor, was significantly increased by GK irradiation. These results suggested that GK irradiation alleviates allodynia via increased GDNF. This study provides novel evidence that GK
Dismantling of Irradiation Facility Selfshielded of Investigation Model MPX- γ-25M
International Nuclear Information System (INIS)
Soguero, D.; Rapado, M.; Prieto, E.; Desdin, L.; Guerra, M.; Castillo, J.
2011-01-01
In this paper is described the dismantling a category I selfshielded gamma irradiation facility model MPX - γ - 25M. The following specific objectives were established: a) identify aspects of the insurance contract, human and technical resources b) assess the radiological situation of the process and c) analyze potential radiological extraordinary events in each step of the process, ensuring appropriate responses, based on an evaluation of process safety. The assessment of radiological events can serve as a reference for addressing the process of dismantling other similar irradiators. (Author)
International Nuclear Information System (INIS)
Chakraborty, Somsubhra; Weindorf, David C.; Li, Bin; Ali, Md. Nasim; Majumdar, K.; Ray, D.P.
2014-01-01
This pilot study compared penalized spline regression (PSR) and random forest (RF) regression using visible and near-infrared diffuse reflectance spectroscopy (VisNIR DRS) derived spectra of 164 petroleum contaminated soils after two different spectral pretreatments [first derivative (FD) and standard normal variate (SNV) followed by detrending] for rapid quantification of soil petroleum contamination. Additionally, a new analytical approach was proposed for the recovery of the pure spectral and concentration profiles of n-hexane present in the unresolved mixture of petroleum contaminated soils using multivariate curve resolution alternating least squares (MCR-ALS). The PSR model using FD spectra (r 2 = 0.87, RMSE = 0.580 log 10 mg kg −1 , and residual prediction deviation = 2.78) outperformed all other models tested. Quantitative results obtained by MCR-ALS for n-hexane in presence of interferences (r 2 = 0.65 and RMSE 0.261 log 10 mg kg −1 ) were comparable to those obtained using FD (PSR) model. Furthermore, MCR ALS was able to recover pure spectra of n-hexane. - Highlights: • We predicted soil petroleum contamination with VisNIR DRS spectra. • We examined 2 spectral pretreatments and 2 multivariate models. • MCR-ALS was used for compositional and spectral resolution of n-hexane. • Penalized spline regression performed best for quantifying soil TPH. • MCR-ALS was promising for resolution of complex soil–petroleum mixture. - Use of VisNIR DRS for rapid quantification of soil TPH and resolution of complex soil petroleum mixtures
Spectral history modeling in the reactor dynamics code DYN3D
International Nuclear Information System (INIS)
Bilodid, Yurii
2014-01-01
A new method of treating spectral history effects in reactor core calculations was developed and verified in this dissertation. The nature of history effects is a dependence of fuel properties not only on the burnup, but also on the local spectral conditions during burnup. The basic idea of the proposed method is the use of the plutonium-239 concentration as the spectral history indicator. The method was implemented in the reactor dynamics code DYN3D and provides a correction for nodal cross sections according to the local spectral history. A verification of the new method was performed by single-assembly calculations in comparison with results of the lattice code HELIOS. The application of plutonium-based history correction significantly improves the cross section estimation accuracy both for UOX and MOX fuel, with quadratic and hexagonal geometry. The new method was applied to evaluate the influence of history effects on full-core calculation results. Analysis of a PWR equilibrium fuel cycle has shown a significant effect on the axial power distribution during a whole cycle, which causes axial temperature and burnup redistributions. The observed neutron flux redistribution improves neutron economy, so the fuel cycle is longer than in calculations without history corrections. Analyses of hypothetical control rod ejection accidents have shown a minor influence of history effects on the transient course and safety relevant parameters.
A Skew-t space-varying regression model for the spectral analysis of resting state brain activity.
Ismail, Salimah; Sun, Wenqi; Nathoo, Farouk S; Babul, Arif; Moiseev, Alexader; Beg, Mirza Faisal; Virji-Babul, Naznin
2013-08-01
It is known that in many neurological disorders such as Down syndrome, main brain rhythms shift their frequencies slightly, and characterizing the spatial distribution of these shifts is of interest. This article reports on the development of a Skew-t mixed model for the spatial analysis of resting state brain activity in healthy controls and individuals with Down syndrome. Time series of oscillatory brain activity are recorded using magnetoencephalography, and spectral summaries are examined at multiple sensor locations across the scalp. We focus on the mean frequency of the power spectral density, and use space-varying regression to examine associations with age, gender and Down syndrome across several scalp regions. Spatial smoothing priors are incorporated based on a multivariate Markov random field, and the markedly non-Gaussian nature of the spectral response variable is accommodated by the use of a Skew-t distribution. A range of models representing different assumptions on the association structure and response distribution are examined, and we conduct model selection using the deviance information criterion. (1) Our analysis suggests region-specific differences between healthy controls and individuals with Down syndrome, particularly in the left and right temporal regions, and produces smoothed maps indicating the scalp topography of the estimated differences.
Construction of a reliable model pyranometer for irradiance ...
African Journals Online (AJOL)
USER
2010-03-22
Mar 22, 2010 ... hour, latitude and cloud cover are the most widely or commonly used ... models in the Nigerian environment include that of Burari and Sambo .... influence the stability of the assembly (reducing its phase ... earth's surface.
The model of self-compensation and pinning of the Fermi level in irradiated semiconductors
International Nuclear Information System (INIS)
Brudnyi, V. N.; Kolin, N. G.; Smirnov, L. S.
2007-01-01
A model is developed to analyze numerically the electrical properties and the steady-state (limiting) position of the Fermi level (F lim ) in tetrahedral semiconductors irradiated with high-energy particles. It is shown that an irradiated semiconductor represents a highly compensated material, in which F lim is identical to G >/2, where G > is the average energy gap between the conduction band and valence band within the entire Brillouin zone of the crystal. The experimental values of F lim , the calculated values of G >/2, and the data on the electrical properties of irradiated semiconductors are presented. The chemical trends controlling the variation in the quantity F lim in groups of semiconductors with the similar types of chemical bonding are analyzed
Modelling UV irradiances on arbitrarily oriented surfaces: effects of sky obstructions
Directory of Open Access Journals (Sweden)
M. Hess
2008-07-01
Full Text Available A method is presented to calculate UV irradiances on inclined surfaces that additionally takes into account the influence of sky obstructions caused by obstacles such as mountains, houses, trees, or umbrellas. With this method it is thus possible to calculate the impact of UV radiation on biological systems, such as, for instance, the human skin or eye, in any natural or artificial environment. The method, which consists of a combination of radiation models, is explained here and the accuracy of its results is demonstrated. The effect of a natural skyline is shown for an Alpine ski area, where the UV irradiance even on a horizontal surface may increase due to reflection from snow by more than 10 percent. In contrast, in a street canyon the irradiance on a horizontal surface is reduced to 30% in shadow and to about 75% for a position in the sun.
Modelling UV irradiances on arbitrarily oriented surfaces: effects of sky obstructions
Hess, M.; Koepke, P.
2008-07-01
A method is presented to calculate UV irradiances on inclined surfaces that additionally takes into account the influence of sky obstructions caused by obstacles such as mountains, houses, trees, or umbrellas. With this method it is thus possible to calculate the impact of UV radiation on biological systems, such as, for instance, the human skin or eye, in any natural or artificial environment. The method, which consists of a combination of radiation models, is explained here and the accuracy of its results is demonstrated. The effect of a natural skyline is shown for an Alpine ski area, where the UV irradiance even on a horizontal surface may increase due to reflection from snow by more than 10 percent. In contrast, in a street canyon the irradiance on a horizontal surface is reduced to 30% in shadow and to about 75% for a position in the sun.
A model of knock-out of oxygen by charged particle irradiation of Bi-2212
International Nuclear Information System (INIS)
Bandyopadhyay, S.K.; Sen, Pintu; Barat, P.; Mukherjee, P.; Das, S.K.; Ghosh, B.
1996-01-01
A model of knock-out of oxygen by charged particle (α and proton) irradiation of Bi 2 Sr 2 CaCu 2 O 8+x (Bi-2212) is proposed on the basis of Monte Carlo TRIM calculations. In Bi-2212, the loosely bound excess oxygen is vulnerable to be displaced by particle irradiation. Binding energy and hence, displacement energy of this loosely bound excess oxygen is less compared to that of stoichiometric lattice bound oxygen and other atoms. The displaced or knocked out oxygen goes to pores or intergranular region and generates large pressure inside the sample. Because of porosity of the material, this displaced oxygen diffuses out and there is a net reduction of oxygen content of the sample. The irradiation induced oxygen knock-out is dominant in the bulk where nonionizing energy loss is maximum. (author). 29 refs., 1 fig., 3 tabs
Microstructure and Mechanical Properties of n-irradiated Fe-Cr Model Alloys
International Nuclear Information System (INIS)
Matijasevic, Milena; Al Mazouzi, Abderrahim
2008-01-01
High chromium ( 9-12 wt %) ferritic/martensitic steels are candidate structural materials for future fusion reactors and other advanced systems such as accelerator driven systems (ADS). Their use for these applications requires a careful assessment of their mechanical stability under high energy neutron irradiation and in aggressive environments. In particular, the Cr concentration has been shown to be a key parameter to be optimized in order to guarantee the best corrosion and swelling resistance, together with the least embrittlement. In this work, the characterization of the neutron irradiated Fe-Cr model alloys with different Cr % with respect to microstructure and mechanical tests will be presented. The behavior of Fe-Cr alloys have been studied using tensile tests at different temperature range ( from -160 deg. C to 300 deg. C). Irradiation-induced microstructure changes have been studied by TEM for two different irradiation doses at 300 deg. C. The density and the size distribution of the defects induced have been determined. The tensile test results indicate that Cr content affects the hardening behavior of Fe-Cr binary alloys. Hardening mechanisms are discussed in terms of Orowan type of approach by correlating TEM data to the measured irradiation hardening. (authors)
Schültke, Elisabeth; Trippel, Michael; Bräuer-Krisch, Elke; Renier, Michel; Bartzsch, Stefan; Requardt, Herwig; Döbrössy, Máté D; Nikkhah, Guido
2013-01-01
We have conducted the first in-vivo experiments in pencilbeam irradiation, a new synchrotron radiation technique based on the principle of microbeam irradiation, a concept of spatially fractionated high-dose irradiation. In an animal model of adult C57 BL/6J mice we have determined technical and physiological limitations with the present technical setup of the technique. Fifty-eight animals were distributed in eleven experimental groups, ten groups receiving whole brain radiotherapy with arrays of 50 µm wide beams. We have tested peak doses ranging between 172 Gy and 2,298 Gy at 3 mm depth. Animals in five groups received whole brain radiotherapy with a center-to-center (ctc) distance of 200 µm and a peak-to-valley ratio (PVDR) of ∼ 100, in the other five groups the ctc was 400 µm (PVDR ∼ 400). Motor and memory abilities were assessed during a six months observation period following irradiation. The lower dose limit, determined by the technical equipment, was at 172 Gy. The LD50 was about 1,164 Gy for a ctc of 200 µm and higher than 2,298 Gy for a ctc of 400 µm. Age-dependent loss in motor and memory performance was seen in all groups. Better overall performance (close to that of healthy controls) was seen in the groups irradiated with a ctc of 400 µm.
Li, Xiaoxia; Wu, Miaoqin; Zhang, Luyi; Liu, Hui; Zhang, Lan; He, Jinjing
2017-12-01
In this study, we evaluated the effect of oral administration of riboflavin combined with whole-body ultraviolet A (UVA) irradiation on the biochemical and biomechanical properties of sclera in a guinea pig model to control the progression of myopia. Experimental groups were administered 0.1% riboflavin solution with or without vitamin C by gavage from 3 days before myopic modeling and during the modeling process. Guinea pigs underwent 30 min of whole-body UVA irradiation after each gavage for 2 weeks. For control groups, guinea pigs were administered vitamin C and underwent either whole-body UVA irradiation without 0.1% riboflavin solution or whole-body fluorescent lamp irradiation with or without 0.1% riboflavin solution. Resultantly, myopia models were established with an increased axial length and myopic diopter. Compared with myopic eyes in the control groups, the net increase in axial length, diopter and strain assessment decreased significantly, and the net decrease in sclera thickness, ultimate load, and stress assessment decreased significantly in experimental groups. MMP-2 expression showed a lower net increase, while TIMP-2 expression showed a lower net decrease. In addition, hyperplasia of scleral fibroblasts was more active in myopic eyes of experimental groups. Overall, our results showed that oral administration of riboflavin with whole-body UVA irradiation could increase the strength and stiffness of sclera by altering the biochemical and biomechanical properties, and decreases in axial elongation and myopic diopter are greater in the guinea pig myopic model. Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights reserved.
Directory of Open Access Journals (Sweden)
P. G. Kosmopoulos
2017-07-01
Full Text Available This study assesses the impact of dust on surface solar radiation focussing on an extreme dust event. For this purpose, we exploited the synergy of AERONET measurements and passive and active satellite remote sensing (MODIS and CALIPSO observations, in conjunction with radiative transfer model (RTM and chemical transport model (CTM simulations and the 1-day forecasts from the Copernicus Atmosphere Monitoring Service (CAMS. The area of interest is the eastern Mediterranean where anomalously high aerosol loads were recorded between 30 January and 3 February 2015. The intensity of the event was extremely high, with aerosol optical depth (AOD reaching 3.5, and optical/microphysical properties suggesting aged dust. RTM and CTM simulations were able to quantify the extent of dust impact on surface irradiances and reveal substantial reduction in solar energy exploitation capacity of PV and CSP installations under this high aerosol load. We found that such an extreme dust event can result in Global Horizontal Irradiance (GHI attenuation by as much as 40–50 % and a much stronger Direct Normal Irradiance (DNI decrease (80–90 %, while spectrally this attenuation is distributed to 37 % in the UV region, 33 % in the visible and around 30 % in the infrared. CAMS forecasts provided a reliable available energy assessment (accuracy within 10 % of that obtained from MODIS. Spatially, the dust plume resulted in a zonally averaged reduction of GHI and DNI of the order of 150 W m−2 in southern Greece, and a mean increase of 20 W m−2 in the northern Greece as a result of lower AOD values combined with local atmospheric processes. This analysis of a real-world scenario contributes to the understanding and quantification of the impact range of high aerosol loads on solar energy and the potential for forecasting power generation failures at sunshine-privileged locations where solar power plants exist, are under construction or are
International Nuclear Information System (INIS)
Ribis, J.
2007-12-01
The fuel rod cladding, strongly affected by microstructural changes due to irradiation such as high density of dislocation loops, is strained by the end-of-life fuel rod internal pressure and the potential release of fission gases and helium during dry storage. Within the temperature range that is expected during dry interim storage, cladding undergoes long term creep under over-pressure. So, in order to have a predictive approach of the behavior of zirconium alloys cladding in dry storage conditions it is essential to take into account: initial dislocation loops, thermal annealing of loops and creep straining due to over pressure. Specific experiments and modelling for irradiated samples have been developed to improve our knowledge in that field. A Zr-1%Nb-O alloy was studied using fine microstructural investigations and mechanical testing. The observations conducted by transmission electron microscopy show that the high density of loops disappears during a heat treatment. The loop size becomes higher and higher while their density falls. The microhardness tests reveal that the fall of loop density leads to the softening of the irradiated material. During a creep test, both temperature and applied stress are responsible of the disappearance of loops. The loops could be swept by the activation of the basal slip system while the prism slip system is inhibited. Once deprived of loops, the creep properties of the irradiated materials are closed to the non irradiated state, a result whose consequence is a sudden acceleration of the creep rate. Finally, a micro-mechanical modeling based on microscopic deformation mechanisms taking into account experimental dislocation loop analyses and creep test, was used for a predictive approach by constructing a deformation mechanism map of the creep behavior of the irradiated material. (author)
International Nuclear Information System (INIS)
Gan, J.; Stoller, R.E.; Was, G.S.
1998-01-01
A model for the development of microstructure during irradiation in fast reactors has been adapted for light water reactor (LWR) irradiation conditions (275 approximately 325 C, up to approximately10 dpa). The original model was based on the rate-theory, and included descriptions of the evolution of both dislocation loops and cavities. The model was modified by introducing in-cascade interstitial clustering, a term to account for the dose dependence of this clustering, and mobility of interstitial clusters. The purpose of this work was to understand microstructural development under LWR irradiation with a focus on loop nucleation and saturation of loop density. It was demonstrated that in-cascade interstitial clustering dominates loop nucleation in neutron irradiation in LWRS. Furthermore it was shown that the dose dependence of in-cascade interstitial clustering is needed to account for saturation behavior as commonly observed. Both quasi-steady-state (QSS) and non-steady-state (NSS) solutions to the rate equations were obtained. The difference between QSS and NSS treatments in the calculation of defect concentration is reduced at LWR temperature when in-cascade interstitial clustering dominates loop nucleation. The mobility of interstitial clusters was also investigated and its impact on loop density is to reduce the nucleation term. The ultimate goal of this study is to combine the evolution of microstructure and microchemistry together to account for the radiation damage in austenitic stainless steels
Directory of Open Access Journals (Sweden)
Saad Motahhir
2018-01-01
Full Text Available The first objective of this work is to determine some of the performance parameters characterizing the behavior of a particular photovoltaic (PV panels that are not normally provided in the manufacturers’ specifications. These provide the basis for developing a simple model for the electrical behavior of the PV panel. Next, using this model, the effects of varying solar irradiation, temperature, series and shunt resistances, and partial shading on the output of the PV panel are presented. In addition, the PV panel model is used to configure a large photovoltaic array. Next, a boost converter for the PV panel is designed. This converter is put between the panel and the load in order to control it by means of a maximum power point tracking (MPPT controller. The MPPT used is based on incremental conductance (INC, and it is demonstrated here that this technique does not respond accurately when solar irradiation is increased. To investigate this, a modified incremental conductance technique is presented in this paper. It is shown that this system does respond accurately and reduces the steady-state oscillations when solar irradiation is increased. Finally, simulations of the conventional and modified algorithm are compared, and the results show that the modified algorithm provides an accurate response to a sudden increase in solar irradiation.
Spectral-Lagrangian methods for collisional models of non-equilibrium statistical states
International Nuclear Information System (INIS)
Gamba, Irene M.; Tharkabhushanam, Sri Harsha
2009-01-01
We propose a new spectral Lagrangian based deterministic solver for the non-linear Boltzmann transport equation (BTE) in d-dimensions for variable hard sphere (VHS) collision kernels with conservative or non-conservative binary interactions. The method is based on symmetries of the Fourier transform of the collision integral, where the complexity in its computation is reduced to a separate integral over the unit sphere S d-1 . The conservation of moments is enforced by Lagrangian constraints. The resulting scheme, implemented in free space, is very versatile and adjusts in a very simple manner to several cases that involve energy dissipation due to local micro-reversibility (inelastic interactions) or elastic models of slowing down process. Our simulations are benchmarked with available exact self-similar solutions, exact moment equations and analytical estimates for the homogeneous Boltzmann equation, both for elastic and inelastic VHS interactions. Benchmarking of the simulations involves the selection of a time self-similar rescaling of the numerical distribution function which is performed using the continuous spectrum of the equation for Maxwell molecules as studied first in Bobylev et al. [A.V. Bobylev, C. Cercignani, G. Toscani, Proof of an asymptotic property of self-similar solutions of the Boltzmann equation for granular materials, Journal of Statistical Physics 111 (2003) 403-417] and generalized to a wide range of related models in Bobylev et al. [A.V. Bobylev, C. Cercignani, I.M. Gamba, On the self-similar asymptotics for generalized non-linear kinetic Maxwell models, Communication in Mathematical Physics, in press. URL: ( )]. The method also produces accurate results in the case of inelastic diffusive Boltzmann equations for hard spheres (inelastic collisions under thermal bath), where overpopulated non-Gaussian exponential tails have been conjectured in computations by stochastic methods [T.V. Noije, M. Ernst, Velocity distributions in homogeneously
International Nuclear Information System (INIS)
Nomura, Takaharu
2006-01-01
We previously showed that Type II diabetes model mice prolonged of their life span by life long low dose rate irradiation. We also found that antioxidant function in variety tissues of some strain of mice were enhancement after low dose/low dose rate irradiation. The prolongation of life span might depend on certain damaged level of reactive oxygen species. We thought the effect of the prolongation was due to the enhancement of the antioxidant activities after irradiation. We investigated whether the enhancement of antioxidant activities after low dose rate irradiation had an effect on life span prolongation. Four-week-old female human premature-aging syndrome model mice, kl/kl (klotho) mice, which the life span of this model mouse is about 65 days, were irradiated with gamma rays at 0.35, 0.70 or 1.2 mGy/hr. The 0.70 mGy/hr-irradiated group remarkably effected on the prolongation of their life span. Some mice of the group were extremely survived for about and more 100 days. Antioxidant activities in the irradiated groups were enhancement by low dose rate irradiation, however the dependence of the dose rates were not clearly difference. These results suggest that the antioxidant activities in this model mouse were enhanced by the low dose rate irradiation, and may make it possible to prolong the life span of this mouse. (author)
A real-time prediction model for post-irradiation malignant cervical lymph nodes.
Lo, W-C; Cheng, P-W; Shueng, P-W; Hsieh, C-H; Chang, Y-L; Liao, L-J
2018-04-01
To establish a real-time predictive scoring model based on sonographic characteristics for identifying malignant cervical lymph nodes (LNs) in cancer patients after neck irradiation. One-hundred forty-four irradiation-treated patients underwent ultrasonography and ultrasound-guided fine-needle aspirations (USgFNAs), and the resultant data were used to construct a real-time and computerised predictive scoring model. This scoring system was further compared with our previously proposed prediction model. A predictive scoring model, 1.35 × (L axis) + 2.03 × (S axis) + 2.27 × (margin) + 1.48 × (echogenic hilum) + 3.7, was generated by stepwise multivariate logistic regression analysis. Neck LNs were considered to be malignant when the score was ≥ 7, corresponding to a sensitivity of 85.5%, specificity of 79.4%, positive predictive value (PPV) of 82.3%, negative predictive value (NPV) of 83.1%, and overall accuracy of 82.6%. When this new model and the original model were compared, the areas under the receiver operating characteristic curve (c-statistic) were 0.89 and 0.81, respectively (P real-time sonographic predictive scoring model was constructed to provide prompt and reliable guidance for USgFNA biopsies to manage cervical LNs after neck irradiation. © 2017 John Wiley & Sons Ltd.
Bucha, Blažej; Hirt, Christian; Kuhn, Michael
2018-04-01
Spectral gravity forward modelling is a technique that converts a band-limited topography into its implied gravitational field. This conversion implicitly relies on global integration of topographic masses. In this paper, a modification of the spectral technique is presented that provides gravity effects induced only by the masses located inside or outside a spherical cap centred at the evaluation point. This is achieved by altitude-dependent Molodensky's truncation coefficients, for which we provide infinite series expansions and recurrence relations with a fixed number of terms. Both representations are generalized for an arbitrary integer power of the topography and arbitrary radial derivative. Because of the altitude-dependency of the truncation coefficients, a straightforward synthesis of the near- and far-zone gravity effects at dense grids on irregular surfaces (e.g. the Earth's topography) is computationally extremely demanding. However, we show that this task can be efficiently performed using an analytical continuation based on the gradient approach, provided that formulae for radial derivatives of the truncation coefficients are available. To demonstrate the new cap-modified spectral technique, we forward model the Earth's degree-360 topography, obtaining near- and far-zone effects on gravity disturbances expanded up to degree 3600. The computation is carried out on the Earth's surface and the results are validated against an independent spatial-domain Newtonian integration (1 μGal RMS agreement). The new technique is expected to assist in mitigating the spectral filter problem of residual terrain modelling and in the efficient construction of full-scale global gravity maps of highest spatial resolution.
Liquid-drop model applied to heavy ions irradiation
International Nuclear Information System (INIS)
De Cicco, Hernan; Alurralde, Martin A.; Saint-Martin, Maria L. G.; Bernaola, Omar A.
1999-01-01
Liquid-drop model is used, previously applied in the study of radiation damage in metals, in an energy range not covered by molecular dynamics, in order to understand experimental data of particle tracks in an organic material (Makrofol E), which cannot be accurately described by the existing theoretical methods. The nuclear and electronic energy depositions are considered for each ion considered and the evolution of the thermal explosion is evaluated. The experimental observation of particle tracks in a region previously considered as 'prohibited' are justified. Although the model used has free parameters and some discrepancies with the experimental diametrical values exist, the agreement obtained is highly superior than that of other existing models. (author)
Can chemical transport models improve global horizontal irradiance forecasts?
Czech Academy of Sciences Publication Activity Database
Brabec, Marek; Konár, Ondřej; Resler, Jaroslav; Krč, Pavel; Pelikán, Emil; Eben, Kryštof
2014-01-01
Roč. 11, - (2014), EMS2014-404 [EMS Annual Meeting /14./ & European Conference on Applied Climatology (ECAC) /10./. 06.10.2014-10.10.2014, Prague] Institutional support: RVO:67985807 Keywords : renewable energy * mathematical modeling Subject RIV: DG - Athmosphere Sciences, Meteorology
Blocquet, M; Guo, F; Mendez, M; Ward, M; Coudert, S; Batut, S; Hecquet, C; Blond, N; Fittschen, C; Schoemaecker, C
2018-05-01
The characteristics of indoor light (intensity, spectral, spatial distribution) originating from outdoors have been studied using experimental and modeling tools. They are influenced by many parameters such as building location, meteorological conditions, and the type of window. They have a direct impact on indoor air quality through a change in chemical processes by varying the photolysis rates of indoor pollutants. Transmittances of different windows have been measured and exhibit different wavelength cutoffs, thus influencing the potential of different species to be photolysed. The spectral distribution of light entering indoors through the windows was measured under different conditions and was found to be weakly dependent on the time of day for indirect cloudy, direct sunshine, partly cloudy conditions contrary to the light intensity, in agreement with calculations of the transmittance as a function of the zenithal angle and the calculated outdoor spectral distribution. The same conclusion can be drawn concerning the position within the room. The impact of these light characteristics on the indoor chemistry has been studied using the INCA-Indoor model by considering the variation in the photolysis rates of key indoor species. Depending on the conditions, photolysis processes can lead to a significant production of radicals and secondary species. © 2018 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.
Multi-time-scale heat transfer modeling of turbid tissues exposed to short-pulsed irradiations.
Kim, Kyunghan; Guo, Zhixiong
2007-05-01
A combined hyperbolic radiation and conduction heat transfer model is developed to simulate multi-time-scale heat transfer in turbid tissues exposed to short-pulsed irradiations. An initial temperature response of a tissue to an ultrashort pulse irradiation is analyzed by the volume-average method in combination with the transient discrete ordinates method for modeling the ultrafast radiation heat transfer. This response is found to reach pseudo steady state within 1 ns for the considered tissues. The single pulse result is then utilized to obtain the temperature response to pulse train irradiation at the microsecond/millisecond time scales. After that, the temperature field is predicted by the hyperbolic heat conduction model which is solved by the MacCormack's scheme with error terms correction. Finally, the hyperbolic conduction is compared with the traditional parabolic heat diffusion model. It is found that the maximum local temperatures are larger in the hyperbolic prediction than the parabolic prediction. In the modeled dermis tissue, a 7% non-dimensional temperature increase is found. After about 10 thermal relaxation times, thermal waves fade away and the predictions between the hyperbolic and parabolic models are consistent.
Energy Technology Data Exchange (ETDEWEB)
Wang, Yuanyuan, E-mail: 630wyy@163.com [Key Laboratory of Materials Modification by Laser, Ion and Electron Beams (Ministry of Education), Dalian University of Technology, Dalian 116024 (China); Zhao, Jijun, E-mail: zhaojj@dlut.edu.cn [Key Laboratory of Materials Modification by Laser, Ion and Electron Beams (Ministry of Education), Dalian University of Technology, Dalian 116024 (China); Zhang, Chi [Key Laboratory of Advanced Materials of Ministry of Education, School of Materials Science and Engineering, Tsinghua University, Beijing 100084 (China)
2017-05-15
Highlights: • The initial internal variable in the Anand model is modified by considering both temperature and irradiation dose. • The tensile stress-strain response is examined and analyzed under different temperatures and irradiation doses. • Yield strengths are predicted as functions of strain rate, temperature and irradiation dose. - Abstract: The viscoplastic equations with a modified initial internal variable are implemented into the finite element code to investigate stress-strain response and irradiation hardening of the materials under increased temperature and at different levels of irradiated dose. We applied this model to Mod 9Cr-1Mo steel. The predicted results are validated by the experimentally measured data. Furthermore, they show good agreement with the previous data from a constitutive crystal plasticity model in account of dislocation and interstitial loops. Three previous hardening models for predicting the yield strength of the material are discussed and compared with our simulation results.
Soot and Spectral Radiation Modeling in ECN Spray A and in Engines
Energy Technology Data Exchange (ETDEWEB)
Haworth, Daniel C [Pennsylvania State Univ., University Park, PA (United States); Ferreyro-Fernandez, Sebastian [Pennsylvania State Univ., University Park, PA (United States); Paul, Chandan [Pennsylvania State Univ., University Park, PA (United States); Sircar, Arpan [Pennsylvania State Univ., University Park, PA (United States); Imren, Abdurrahman [Pennsylvania State Univ., University Park, PA (United States); Roy, Somesh P [Marquette University (United States); Modest, Michael F [University of California Merced (United States); Ge, Wenjun [University of California Merced (United States)
2017-04-03
The amount of soot formed in a turbulent combustion system is determined by a complex system of coupled nonlinear chemical and physical processes. Different physical subprocesses can dominate, depending on the hydrodynamic and thermochemical environments. Similarly, the relative importance of reabsorption, spectral radiation properties, and molecular gas radiation versus soot radiation varies with thermochemical conditions, and in ways that are difficult to predict for the highly nonhomogeneous in-cylinder mixtures in engines. Here it is shown that transport and mixing play relatively more important roles as rate-determining processes in soot formation at engine-relevant conditions. It is also shown that molecular gas radiation and spectral radiation properties are important for engine-relevant conditions.
Effects of Irradiation on Brain Vasculature Using an In Situ Tumor Model
Energy Technology Data Exchange (ETDEWEB)
Zawaski, Janice A. [School of Biomedical Engineering and Imaging, University of Tennessee Health Science Center, Memphis, TN (United States); Gaber, M. Waleed, E-mail: gaber@bcm.edu [School of Biomedical Engineering and Imaging, University of Tennessee Health Science Center, Memphis, TN (United States); Department of Pediatrics, Baylor College of Medicine, Houston, TX (United States); Sabek, Omaima M. [Department of Surgery, Methodist Hospital Research Institute, Houston, TX (United States); Wilson, Christy M. [School of Biomedical Engineering and Imaging, University of Tennessee Health Science Center, Memphis, TN (United States); Duntsch, Christopher D. [Department of Neurosurgery, University of Tennessee Health Science Center, Memphis, TN (United States); Merchant, Thomas E. [School of Biomedical Engineering and Imaging, University of Tennessee Health Science Center, Memphis, TN (United States); Department of Radiation Oncology, St. Jude Children' s Research Hospital, Memphis, TN (United States)
2012-03-01
Purpose: Damage to normal tissue is a limiting factor in clinical radiotherapy (RT). We tested the hypothesis that the presence of tumor alters the response of normal tissues to irradiation using a rat in situ brain tumor model. Methods and Materials: Intravital microscopy was used with a rat cranial window to assess the in situ effect of rat C6 glioma on peritumoral tissue with and without RT. The RT regimen included 40 Gy at 8 Gy/day starting Day 5 after tumor implant. Endpoints included blood-brain barrier permeability, clearance index, leukocyte-endothelial interactions and staining for vascular endothelial growth factor (VEGF) glial fibrillary acidic protein, and apoptosis. To characterize the system response to RT, animal survival and tumor surface area and volume were measured. Sham experiments were performed on similar animals implanted with basement membrane matrix absent of tumor cells. Results: The presence of tumor alone increases permeability but has little effect on leukocyte-endothelial interactions and astrogliosis. Radiation alone increases tissue permeability, leukocyte-endothelial interactions, and astrogliosis. The highest levels of permeability and cell adhesion were seen in the model that combined tumor and irradiation; however, the presence of tumor appeared to reduce the volume of rolling leukocytes. Unirradiated tumor and peritumoral tissue had poor clearance. Irradiated tumor and peritumoral tissue had a similar clearance index to irradiated and unirradiated sham-implanted animals. Radiation reduces the presence of VEGF in peritumoral normal tissues but did not affect the amount of apoptosis in the normal tissue. Apoptosis was identified in the tumor tissue with and without radiation. Conclusions: We developed a novel approach to demonstrate that the presence of the tumor in a rat intracranial model alters the response of normal tissues to irradiation.
EFFECTS OF IRRADIATION ON BRAIN VASCULATURE USING AN IN SITU TUMOR MODEL
Zawaski, Janice A.; Gaber, M. Waleed; Sabek, Omaima M.; Wilson, Christy M.; Duntsch, Christopher D.; Merchant, Thomas E.
2013-01-01
Purpose Damage to normal tissue is a limiting factor in clinical radiotherapy (RT). We tested the hypothesis that the presence of tumor alters the response of normal tissues to irradiation using a rat in situ brain tumor model. Methods and Materials Intravital microscopy was used with a rat cranial window to assess the in situ effect of rat C6 glioma on peritumoral tissue with and without RT. The RT regimen included 40 Gy at 8 Gy/day starting Day 5 after tumor implant. Endpoints included blood–brain barrier permeability, clearance index, leukocyte-endothelial interactions and staining for vascular endothelial growth factor (VEGF) glial fibrillary acidic protein, and apoptosis. To characterize the system response to RT, animal survival and tumor surface area and volume were measured. Sham experiments were performed on similar animals implanted with basement membrane matrix absent of tumor cells. Results The presence of tumor alone increases permeability but has little effect on leukocyte–endothelial interactions and astrogliosis. Radiation alone increases tissue permeability, leukocyte-endothelial interactions, and astrogliosis. The highest levels of permeability and cell adhesion were seen in the model that combined tumor and irradiation; however, the presence of tumor appeared to reduce the volume of rolling leukocytes. Unirradiated tumor and peritumoral tissue had poor clearance. Irradiated tumor and peritumoral tissue had a similar clearance index to irradiated and unirradiated sham-implanted animals. Radiation reduces the presence of VEGF in peritumoral normal tissues but did not affect the amount of apoptosis in the normal tissue. Apoptosis was identified in the tumor tissue with and without radiation. Conclusions We developed a novel approach to demonstrate that the presence of the tumor in a rat intracranial model alters the response of normal tissues to irradiation. PMID:22197233
Energy Technology Data Exchange (ETDEWEB)
McAnulty, Michael J., E-mail: mcanulmj@id.doe.gov [Department of Energy, 1955 Fremont Avenue, Idaho Falls, ID 83402 (United States); Potirniche, Gabriel P. [Mechanical Engineering Department, University of Idaho, Moscow, ID 83844 (United States); Tokuhiro, Akira [Mechanical Engineering Department, University of Idaho, Idaho Falls, ID 83402 (United States)
2012-09-15
Highlights: Black-Right-Pointing-Pointer An internal state variable approach is used to predict the plastic behavior of irradiated metals. Black-Right-Pointing-Pointer The model predicts uniaxial tensile test data for irradiated 304L stainless steel. Black-Right-Pointing-Pointer The model is implemented as a user-defined material subroutine in the finite element code ABAQUS. Black-Right-Pointing-Pointer Results are compared for the unirradiated and irradiated specimens loaded in uniaxial tension. - Abstract: Neutron irradiation of metals results in decreased fracture toughness, decreased ductility, increased yield strength and increased ductile-to-brittle transition temperature. Designers use the most limiting material properties throughout the reactor vessel lifetime to determine acceptable safety margins. To reduce analysis conservatism, a new model is proposed based on an internal state variable approach for the plastic behavior of unirradiated ductile materials to support its use for analyzing irradiated materials. The proposed modeling addresses low temperature irradiation of 304L stainless steel, and predicts uniaxial tensile test data of irradiated experimental specimens. The model was implemented as a user-defined material subroutine (UMAT) in the finite element software ABAQUS. Results are compared between the unirradiated and irradiated specimens subjected to tension tests.
Prokhorov, Alexander; Prokhorova, Nina I
2012-11-20
We applied the bidirectional reflectance distribution function (BRDF) model consisting of diffuse, quasi-specular, and glossy components to the Monte Carlo modeling of spectral effective emissivities for nonisothermal cavities. A method for extension of a monochromatic three-component (3C) BRDF model to a continuous spectral range is proposed. The initial data for this method are the BRDFs measured in the plane of incidence at a single wavelength and several incidence angles and directional-hemispherical reflectance measured at one incidence angle within a finite spectral range. We proposed the Monte Carlo algorithm for calculation of spectral effective emissivities for nonisothermal cavities whose internal surface is described by the wavelength-dependent 3C BRDF model. The results obtained for a cylindroconical nonisothermal cavity are discussed and compared with results obtained using the conventional specular-diffuse model.
Humpage, Neil; Green, Paul D.; Harries, John E.
2009-03-01
Recent studies have highlighted the important contribution of the far-infrared (electromagnetic radiation with wavelengths greater than 12 μm) to the Earth's radiative energy budget. In a cloud-free atmosphere, a significant fraction of the Earth's cooling to space from the mid- and upper troposphere takes place via the water vapor pure rotational band between 17 and 33 μm. Cirrus clouds also play an important role in the Earth's outgoing longwave radiation. The effect of cirrus on far-infrared radiation is of particular interest, since the refractive index of ice depends strongly on wavelength in this spectral region. The scattering properties of ice crystals are directly related to the refractive index, so consequently the spectral signature of cirrus measured in the FIR is sensitive to the cloud microphysical properties [1, 2]. By examining radiances measured at wavelengths between the strong water vapor absorption lines in the FIR, the understanding of the relationship between cirrus microphysics and the radiative transfer of thermal energy through cirrus may be improved. Until recently, very few observations of FIR spectral radiances had been made. The Tropospheric Airborne Fourier Transform Spectrometer (TAFTS) was developed by Imperial College to address this lack of observational data. TAFTS observes both zenith and nadir radiances at 0.1 cm-1 resolution, between 80 and 600 cm-1. During February and March 2007, TAFTS was involved in RHUBC (the Radiative Heating in Under-explored Bands Campaign), an ARM funded field campaign based at the ACRF-North Slope of Alaska site near Barrow, situated at 71° latitude. Infrared zenith spectral observations were taken by both TAFTS and the AERI-ER (spectral range 400-3300 cm-1) from the ground during both cloud-free and cirrus conditions. A wide range of other instrumentation was also available at the site, including a micropulse lidar, 35 GHz radar and the University of Colorado/NOAA Ground-based Scanning Radiometer
Energy Technology Data Exchange (ETDEWEB)
Marquis, Emmanuelle [Univ. of Michigan, Ann Arbor, MI (United States); Wirth, Brian [Univ. of Tennessee, Knoxville, TN (United States); Was, Gary [Univ. of Michigan, Ann Arbor, MI (United States)
2016-03-28
Ferritic/martensitic (FM) steels such as HT-9, T-91 and NF12 with chromium concentrations in the range of 9-12 at.% Cr and high Cr ferritic steels (oxide dispersion strengthened steels with 12-18% Cr) are receiving increasing attention for advanced nuclear applications, e.g. cladding and duct materials for sodium fast reactors, pressure vessels in Generation IV reactors and first wall structures in fusion reactors, thanks to their advantages over austenitic alloys. Predicting the behavior of these alloys under radiation is an essential step towards the use of these alloys. Several radiation-induced phenomena need to be taken into account, including phase separation, solute clustering, and radiation-induced segregation or depletion (RIS) to point defect sinks. RIS at grain boundaries has raised significant interest because of its role in irradiation assisted stress corrosion cracking (IASCC) and corrosion of structural materials. Numerous observations of RIS have been reported on austenitic stainless steels where it is generally found that Cr depletes at grain boundaries, consistently with Cr atoms being oversized in the fcc Fe matrix. While FM and ferritic steels are also subject to RIS at grain boundaries, unlike austenitic steels, the behavior of Cr is less clear with significant scatter and no clear dependency on irradiation condition or alloy type. In addition to the lack of conclusive experimental evidence regarding RIS in F-M alloys, there have been relatively few efforts at modeling RIS behavior in these alloys. The need for predictability of materials behavior and mitigation routes for IASCC requires elucidating the origin of the variable Cr behavior. A systematic detailed high-resolution structural and chemical characterization approach was applied to ion-implanted and neutron-irradiated model Fe-Cr alloys containing from 3 to 18 at.% Cr. Atom probe tomography analyses of the microstructures revealed slight Cr clustering and segregation to dislocations and
Directory of Open Access Journals (Sweden)
Amelia H. Cooper
2016-08-01
Full Text Available A surface wave model using three nested grids is applied to the eastern end of Lake Ontario to investigate wave propagation from an open lake environment to a small craft harbour protected by a breakwater. The Simulating WAves Nearshore (SWAN spectral wave model, coupled with the Delft3D hydrodynamic model, is applied to simulate a series of storms in November, 2013. The model results are compared to observations from two pressure sensors, and used to quantify wave properties around existing and future breakwaters to evaluate the bulk changes to the harbour configuration. Overall, the results indicate that the rubblemound breakwater reduces wave heights in the existing harbour by 63% compared to no breakwater, and that the addition of a surface breakwater extension could reduce wave heights by an additional 54%. Wave height attenuation was found to be highly dependent on the incident wave direction relative to breakwater orientation. The spectral wave model is useful for simulating wave transformation for broad directional spectra in wind-sea conditions over large scales to semi-protected areas such as small craft harbours.
International Nuclear Information System (INIS)
Vasilev, V.; Doncheva, B.
1989-01-01
A model is presented for irradiation calculation of human foetus during weeks 8-15 of the intrauterine development, when the mother chronically incorporates iodine 131. This period is critical for the nervous system of the foetus. Compared to some other author's models, the method proposed eliminates some uncertainties and takes into account the changes in the activity of mother's thyroid in time. The model is built on the base of data from 131 I-kinetics of pregnant women and experimental mice. A formula is proposed for total foetus irradiation calculation including: the internal γ and β irradiation; the external γ and β irradiation from the mother as a whole; and the external γ irradiation from the mother's thyroid
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.
Study of irradiated F82H steel and its model Fe-Cr alloy by Moessbauer spectroscopy
International Nuclear Information System (INIS)
Huang, S.S.; Kitao, S.; Xu, Q.; Sato, K.; Yoshiie, T.
2013-01-01
In this work, Moessbauer spectroscopy which is a super-precision tool was conducted on F82H and its model Fe-Cr alloys before and after irradiation to take a further look on the interaction between carbides and point defects and Cr effect on microstructural evolution during irradiation in void incubation period. (J.P.N.)
Energy Technology Data Exchange (ETDEWEB)
Park, Ji Seon; Oh, Joo Hyeong; Kim, Deog Yoon; Park, Yong Koo; Kim, Soo Joong [Kyung Hee University Medical Center, Seoul (Korea, Republic of); Park, Sang Joon [Kang Dong Sacred Heart Hospital, Hallym University, Seoul (Korea, Republic of)
2007-04-15
We wanted to evaluate the effectiveness of intraluminal irradiation with Holmium-166 ({sup 166}Ho) for reducing the pseudointimal hyperplasia (PIH) in the transjugular intrahepatic portosystemic shunt (TIPS) tract in a swine model. TIPS was performed in 12 domestic pigs, after the creation of portal hypertension by intraportal injection of a mixture of N-butyl-2- cyanoacrylate (NBCA) and lipiodol. Five pigs first underwent intraluminal irradiation (30 Gy) in the parenchymal tract with using a {sup 166}Ho solution-filled balloon catheter, and this was followed by the placement of a nitinol stent in the TIPS tract. For the seven control pigs, the balloon was filled with saline and contrast media mixture. Two weeks later, follow-up portography and histological analysis were performed. TIPS was successfully performed in all twelve pigs with achieving artificially induced portal hypertension. Portography performed two weeks after TIPS showed the patent tracts in the TIPS tracts that were irradiated with {sup 166}Ho (5/5, 100%), whereas either completely (5/6, 83.3%) or partially (1/6, 16.7%) occluded TIPS were seen in the seven pigs of the nonirradiated control group, except in one pig that experienced periprocedural death due to bleeding. Histological analysis showed a statistically significant difference for the maximal PIH (irradiated: 32.8%, nonirradiated: 76.0%, p < 0.001) between the two groups. Intraluminal irradiation with 30 Gy of {sup 166}Ho for TIPS significantly improved the TIPS patency in a swine model of portal hypertension during a 2- week period of follow-up.
Prediction model for oxide thickness on aluminum alloy cladding during irradiation
International Nuclear Information System (INIS)
Kim, Yeon Soo; Hofman, G.L.; Hanan, N.A.; Snelgrove, J.L.
2003-01-01
An empirical model predicting the oxide film thickness on aluminum alloy cladding during irradiation has been developed as a function of irradiation time, temperature, heat flux, pH, and coolant flow rate. The existing models in the literature are neither consistent among themselves nor fit the measured data very well. They also lack versatility for various reactor situations such as a pH other than 5, high coolant flow rates, and fuel life longer than ∼1200 hrs. Particularly, they were not intended for use in irradiation situations. The newly developed model is applicable to these in-reactor situations as well as ex-reactor tests, and has a more accurate prediction capability. The new model demonstrated with consistent predictions to the measured data of UMUS and SIMONE fuel tests performed in the HFR, Petten, tests results from the ORR, and IRIS tests from the OSIRIS and to the data from the out-of-pile tests available in the literature as well. (author)
3D Monte Carlo model of optical transport in laser-irradiated cutaneous vascular malformations
Majaron, Boris; Milanič, Matija; Jia, Wangcun; Nelson, J. S.
2010-11-01
We have developed a three-dimensional Monte Carlo (MC) model of optical transport in skin and applied it to analysis of port wine stain treatment with sequential laser irradiation and intermittent cryogen spray cooling. Our MC model extends the approaches of the popular multi-layer model by Wang et al.1 to three dimensions, thus allowing treatment of skin inclusions with more complex geometries and arbitrary irradiation patterns. To overcome the obvious drawbacks of either "escape" or "mirror" boundary conditions at the lateral boundaries of the finely discretized volume of interest (VOI), photons exiting the VOI are propagated in laterally infinite tissue layers with appropriate optical properties, until they loose all their energy, escape into the air, or return to the VOI, but the energy deposition outside of the VOI is not computed and recorded. After discussing the selection of tissue parameters, we apply the model to analysis of blood photocoagulation and collateral thermal damage in treatment of port wine stain (PWS) lesions with sequential laser irradiation and intermittent cryogen spray cooling.
International Nuclear Information System (INIS)
Zempila, Melina-Maria; Taylor, Michael; Bais, Alkiviadis; Kazadzis, Stelios
2016-01-01
We report on the construction of generic models to calculate photosynthetically active radiation (PAR) from global horizontal irradiance (GHI), and vice versa. Our study took place at stations of the Greek UV network (UVNET) and the Hellenic solar energy network (HNSE) with measurements from NILU-UV multi-filter radiometers and CM pyranometers, chosen due to their long (≈1 M record/site) high temporal resolution (≈1 min) record that captures a broad range of atmospheric environments and cloudiness conditions. The uncertainty of the PAR measurements is quantified to be ±6.5% while the uncertainty involved in GHI measurements is up to ≈±7% according to the manufacturer. We show how multi-linear regression and nonlinear neural network (NN) models, trained at a calibration site (Thessaloniki) can be made generic provided that the input–output time series are processed with multi-channel singular spectrum analysis (M-SSA). Without M-SSA, both linear and nonlinear models perform well only locally. M-SSA with 50 time-lags is found to be sufficient for identification of trend, periodic and noise components in aerosol, cloud parameters and irradiance, and to construct regularized noise models of PAR from GHI irradiances. Reconstructed PAR and GHI time series capture ≈95% of the variance of the cross-validated target measurements and have median absolute percentage errors <2%. The intra-site median absolute error of M-SSA processed models were ≈8.2±1.7 W/m"2 for PAR and ≈9.2±4.2 W/m"2 for GHI. When applying the models trained at Thessaloniki to other stations, the average absolute mean bias between the model estimates and measured values was found to be ≈1.2 W/m"2 for PAR and ≈0.8 W/m"2 for GHI. For the models, percentage errors are well within the uncertainty of the measurements at all sites. Generic NN models were found to perform marginally better than their linear counterparts. - Highlights: • Generic linear regression and nonlinear neural network
International Nuclear Information System (INIS)
Parent, Laure; Seco, Joao; Evans, Phil M.; Fielding, Andrew; Dance, David R.
2006-01-01
This study focused on predicting the electronic portal imaging device (EPID) image of intensity modulated radiation treatment (IMRT) fields in the absence of attenuation material in the beam with Monte Carlo methods. As IMRT treatments consist of a series of segments of various sizes that are not always delivered on the central axis, large spectral variations may be observed between the segments. The effect of these spectral variations on the EPID response was studied with fields of various sizes and off-axis positions. A detailed description of the EPID was implemented in a Monte Carlo model. The EPID model was validated by comparing the EPID output factors for field sizes between 1x1 and 26x26 cm 2 at the isocenter. The Monte Carlo simulations agreed with the measurements to within 1.5%. The Monte Carlo model succeeded in predicting the EPID response at the center of the fields of various sizes and offsets to within 1% of the measurements. Large variations (up to 29%) of the EPID response were observed between the various offsets. The EPID response increased with field size and with field offset for most cases. The Monte Carlo model was then used to predict the image of a simple test IMRT field delivered on the beam axis and with an offset. A variation of EPID response up to 28% was found between the on- and off-axis delivery. Finally, two clinical IMRT fields were simulated and compared to the measurements. For all IMRT fields, simulations and measurements agreed within 3%--0.2 cm for 98% of the pixels. The spectral variations were quantified by extracting from the spectra at the center of the fields the total photon yield (Y total ), the photon yield below 1 MeV (Y low ), and the percentage of photons below 1 MeV (P low ). For the studied cases, a correlation was shown between the EPID response variation and Y total , Y low , and P low
Summary report on the fuel performance modeling of the AFC-2A, 2B irradiation experiments
Energy Technology Data Exchange (ETDEWEB)
Pavel G. Medvedev
2013-09-01
The primary objective of this work at the Idaho National Laboratory (INL) is to determine the fuel and cladding temperature history during irradiation of the AFC-2A, 2B transmutation metallic fuel alloy irradiation experiments containing transuranic and rare earth elements. Addition of the rare earth elements intends to simulate potential fission product carry-over from pyro-metallurgical reprocessing. Post irradiation examination of the AFC-2A, 2B rodlets revealed breaches in the rodlets and fuel melting which was attributed to the release of the fission gas into the helium gap between the rodlet cladding and the capsule which houses six individually encapsulated rodlets. This release is not anticipated during nominal operation of the AFC irradiation vehicle that features a double encapsulated design in which sodium bonded metallic fuel is separated from the ATR coolant by the cladding and the capsule walls. The modeling effort is focused on assessing effects of this unanticipated event on the fuel and cladding temperature with an objective to compare calculated results with the temperature limits of the fuel and the cladding.
Models of mixed irradiation with a 'reciprocal-time' pattern of the repair function
Energy Technology Data Exchange (ETDEWEB)
Suzuki, Shozo; Miura, Yuri; Mizuno, Shoichi [Tokyo Metropolitan Inst. of Gerontology (Japan); Furusawa, Yoshiya [National Inst. of Radiological Sciences, Chiba (Japan)
2002-09-01
Suzuki presented models for mixed irradiation with two and multiple types of radiation by extending the Zaider and Rossi model, which is based on the theory of dual radiation action. In these models, the repair function was simply assumed to be semi-logarithmically linear (i.e., monoexponential), or a first-order process, which has been experimentally contradicted. Fowler, however, suggested that the repair of radiation damage might be largely a second-order process rather than a first-order one, and presented data in support of this hypothesis. In addition, a second-order repair function is preferred to an n-exponential repair function for the reason that only one parameter is used in the former instead of 2n-1 parameters for the latter, although both repair functions show a good fit to the experimental data. However, according to a second-order repair function, the repair rate depends on the dose, which is incompatible with the experimental data. We, therefore, revised the models for mixed irradiation by Zaider and Rossi and by Suzuki, by substituting a 'reciprocal-time' pattern of the repair function, which is derived from the assumption that the repair rate is independent of the dose in a second-order repair function, for a first-order one in reduction and interaction factors of the models, although the underlying mechanism for this assumption cannot be well-explained. The reduction factor, which reduces the contribution of the square of a dose to cell killing in the linear-quadratic model and its derivatives, and the interaction factor, which also reduces the contribution of the interaction of two or more doses of different types of radiation, were formulated by using a 'reciprocal-time' patterns of the repair function. Cell survivals calculated from the older and the newly modified models were compared in terms of the dose-rate by assuming various types of single and mixed irradiation. The result implies that the newly modified models for
Validation of the α-μ Model of the Power Spectral Density of GPS Ionospheric Amplitude Scintillation
Directory of Open Access Journals (Sweden)
Kelias Oliveira
2014-01-01
Full Text Available The α-μ model has become widely used in statistical analyses of radio channels, due to the flexibility provided by its two degrees of freedom. Among several applications, it has been used in the characterization of low-latitude amplitude scintillation, which frequently occurs during the nighttime of particular seasons of high solar flux years, affecting radio signals that propagate through the ionosphere. Depending on temporal and spatial distributions, ionospheric scintillation may cause availability and precision problems to users of global navigation satellite systems. The present work initially stresses the importance of the flexibility provided by α-μ model in comparison with the limitations of a single-parameter distribution for the representation of first-order statistics of amplitude scintillation. Next, it focuses on the statistical evaluation of the power spectral density of ionospheric amplitude scintillation. The formulation based on the α-μ model is developed and validated using experimental data obtained in São José dos Campos (23.1°S; 45.8°W; dip latitude 17.3°S, Brazil, located near the southern crest of the ionospheric equatorial ionization anomaly. These data were collected between December 2001 and January 2002, a period of high solar flux conditions. The results show that the proposed model fits power spectral densities estimated from field data quite well.
Zhu, F.; Emile-Geay, J.; Ault, T.; McKay, N.; Dee, S.
2017-12-01
A grand challenge for paleoclimatology is to constrain climate model behavior on timescales longer than the instrumental record. Of particular interest is the spectrum of temperature as sensed by climate proxies. The "continuum" of climate variability [Huybers & Curry, Nature 2006] is often characterized by its scaling exponent β , where the spectral density S and the frequency f satisfy the power law S ∝ f-β . Recent studies have voiced concern that climate models underestimate scaling behavior compared to proxies [Laepple & Huybers, PNAS 2014]. Part of this discrepancy is known to lie in the complex processes whereby proxies transform climate signals [Dee et al, EPSL in press], yet many questions remain open. Here we leverage a recent multiproxy compilation [PAGES 2k Consortium, Sci Data 2017] to characterize scaling behavior over the Common Era using an interpolation-free method [Kirchner & Neal, PNAS 2013]. Proxy spectra are compared to spectra derived from the CESM Last Millennium Ensemble [Otto-Bliesner et al, BAMS 2016], using: (a) a naive model where proxies are assumed linearly related to annual temperature vs (b) proxy system models [Evans et al, QSR 2013] of varying complexity. Scaling behavior varies considerably by archive: on average the strongest centennial slopes are observed for lake sediments (β =1.2), while the smallest are observed for glacier ice (β =0.24). Results confirm that the CESM Last Millennium simulation (LM) exhibits decadal-centennial scaling closer to proxy spectra than the pre-industrial control run (PI): the latter shows a "blue" spectrum (β 0), suggesting that forcings are essential to reduce the spectral divide. Yet, even with forcings, LM spectra are flatter than the proxy spectra. Subsequent work will investigate the roles of seasonal sensitivity (trees, foraminifera, alkenones), multivariate influences (corals, trees), detrending (trees) and post-depositional processes (ice cores, lake & marine sediments) on spectral
Modelling UV irradiances on arbitrarily oriented surfaces: effects of sky obstructions
Hess, M.; Koepke, P.
2008-01-01
A method is presented to calculate UV irradiances on inclined surfaces that additionally takes into account the influence of sky obstructions caused by obstacles such as mountains, houses, trees, or umbrellas. With this method it is thus possible to calculate the impact of UV radiation on biological systems, such as, for instance, the human skin or eye, in any natural or artificial environment. The method, which consists of a combination of radiation models, is explained here and the accuracy...
Statistical thermodynamics and mean-field theory for the alloy under irradiation model
International Nuclear Information System (INIS)
Kamyshendo, V.
1993-01-01
A generalization of statistical thermodynamics to the open systems case, is discussed, using as an example the alloy-under-irradiation model. The statistical properties of stationary states are described with the use of generalized thermodynamic potentials and 'quasi-interactions' determined from the master equation for micro-configuration probabilities. Methods for resolving this equation are illustrated by the mean-field type calculations of correlators, thermodynamic potentials and phase diagrams for disordered alloys
Maslovskaya, A. G.; Barabash, T. K.
2018-03-01
The paper presents the results of the fractal and multifractal analysis of polarization switching current in ferroelectrics under electron irradiation, which allows statistical memory effects to be estimated at dynamics of domain structure. The mathematical model of formation of electron beam-induced polarization current in ferroelectrics was suggested taking into account the fractal nature of domain structure dynamics. In order to realize the model the computational scheme was constructed using the numerical solution approximation of fractional differential equation. Evidences of electron beam-induced polarization switching process in ferroelectrics were specified at a variation of control model parameters.
2016-11-21
AFRL-RD-PS- AFRL-RD-PS- TN-2016-0003 TN-2016-0003 A Model for Microcontroller Functionality Upset Induced by External Pulsed Electromagnetic...TYPE Technical Note 3. DATES COVERED (From - To) 22-11-2015 – 21-11-2016 4. TITLE AND SUBTITLE A Model for Microcontroller Functionality Upset Induced by... microcontroller (µC) subjected to external irradiation by a narrowband electromagnetic (EM) pulse. In our model, the state of a µC is completely specified by
International Nuclear Information System (INIS)
Kota, V.K.B.
1991-01-01
In the interacting boson-fermion model of collective nuclei, in the symmetry limits of the model appropriate for vibrational, rotational and γ-unstable nuclei, for one-particle transfer, the selection rules, model predictions for the allowed strengths and comparison of theory with experiment are briefly reviewed. In the spectral-averaging theory, with the specific example of orbit occupancies, the smoothed forms (linear or better ratio of Gaussians) as determined by central limit theorems, how they provide a good criterion for selecting effective interactions and the convolution structure of occupancy densities in huge spaces are described. Complementary information provided by nuclear models and statistical laws is broughtout. (author). 63 refs., 5 figs
Kenyon, Scott J.; Calvet, Nuria; Hartmann, Lee
1993-01-01
We describe radiative transfer calculations of infalling, dusty envelopes surrounding pre-main-sequence stars and use these models to derive physical properties for a sample of 21 heavily reddened young stars in the Taurus-Auriga molecular cloud. The density distributions needed to match the FIR peaks in the spectral energy distributions of these embedded sources suggest mass infall rates similar to those predicted for simple thermally supported clouds with temperatures about 10 K. Unless the dust opacities are badly in error, our models require substantial departures from spherical symmetry in the envelopes of all sources. These flattened envelopes may be produced by a combination of rotation and cavities excavated by bipolar flows. The rotating infall models of Terebey et al. (1984) models indicate a centrifugal radius of about 70 AU for many objects if rotation is the only important physical effect, and this radius is reasonably consistent with typical estimates for the sizes of circumstellar disks around T Tauri stars.
Water vapor transmittance models for narrow bands in the 13 to 19 μm spectral region
International Nuclear Information System (INIS)
Weichel, R.L.
1983-10-01
The purpose of this report is to document the development of water vapor transmittance models for narrow bands (satellite sensor channels) in the 13 to 19 μm spectral region. The models are the result of research efforts of the author in 1971-1972 while on active duty with the US Air Force at the Air Force Global Weather Central (AFGWC). The models were developed for application in studies involving a temperature profiling sensor system carried aboard the satellites of the Defense Meteorological Satellite Program (DMSP), formerly DAPP. Recently, (Lovill et al., 1978; Luther et al., 1981) the models were implemented for studies concerned with methodologies to retrieve total atmospheric column ozone from measurements of newer DMSP Block 5D series satellite sensors with similar channels (see Nichols, 1975)
Directory of Open Access Journals (Sweden)
Hua Sun
2015-11-01
Full Text Available Accurately mapping urban vegetation carbon density is challenging because of complex landscapes and mixed pixel