WorldWideScience

Sample records for simulate net radiation

  1. A simulation model for the actual, long wave and net solar radiation computing

    Kolev, B.; Stoilov, A.; Lyubomirov, L.

    2004-01-01

    The main purpose of this study is to present a calculating procedure for the components of the radiation balance - actual, long-wave and net radiation calculation, using the sunshine duration and the standard meteorological information, through a previously prepared program product.To calculate the actual solar radiation using the total cloudiness only, an empirical regression model has been developed. The results of the coefficient of correlation R(0.75-0.88), respectively for the spring and summer periods (March-May; June-August) show the adequacy of the chosen model. The verification of the model on the independent experimental material prove that the approach that authors suggested, can be successfully applied to the calculation of the actual radiation of the current place

  2. Simulated Seasonal Spatio-Temporal Patterns of Soil Moisture, Temperature, and Net Radiation in a Deciduous Forest

    Ballard, Jerrell R., Jr.; Howington, Stacy E.; Cinnella, Pasquale; Smith, James A.

    2011-01-01

    The temperature and moisture regimes in a forest are key components in the forest ecosystem dynamics. Observations and studies indicate that the internal temperature distribution and moisture content of the tree influence not only growth and development, but onset and cessation of cambial activity [1], resistance to insect predation[2], and even affect the population dynamics of the insects [3]. Moreover, temperature directly affects the uptake and metabolism of population from the soil into the tree tissue [4]. Additional studies show that soil and atmospheric temperatures are significant parameters that limit the growth of trees and impose treeline elevation limitation [5]. Directional thermal infrared radiance effects have long been observed in natural backgrounds [6]. In earlier work, we illustrated the use of physically-based models to simulate directional effects in thermal imaging [7-8]. In this paper, we illustrated the use of physically-based models to simulate directional effects in thermal, and net radiation in a adeciduous forest using our recently developed three-dimensional, macro-scale computational tool that simulates the heat and mass transfer interaction in a soil-root-stem systems (SRSS). The SRSS model includes the coupling of existing heat and mass transport tools to stimulate the diurnal internal and external temperatures, internal fluid flow and moisture distribution, and heat flow in the system.

  3. Comparison of the performance of net radiation calculation models

    Kjærsgaard, Jeppe Hvelplund; Cuenca, R.H.; Martinez-Cob, A.

    2009-01-01

    . The long-wave radiation models included a physically based model, an empirical model from the literature, and a new empirical model. Both empirical models used only solar radiation as required for meteorological input. The long-wave radiation models were used with model calibration coefficients from......Daily values of net radiation are used in many applications of crop-growth modeling and agricultural water management. Measurements of net radiation are not part of the routine measurement program at many weather stations and are commonly estimated based on other meteorological parameters. Daily...... values of net radiation were calculated using three net outgoing long-wave radiation models and compared to measured values. Four meteorological datasets representing two climate regimes, a sub-humid, high-latitude environment and a semi-arid mid-latitude environment, were used to test the models...

  4. Data error effects on net radiation and evapotranspiration estimation

    Llasat, M.C.; Snyder, R.L.

    1998-01-01

    The objective of this paper is to evaluate the potential error in estimating the net radiation and reference evapotranspiration resulting from errors in the measurement or estimation of weather parameters. A methodology for estimating the net radiation using hourly weather variables measured at a typical agrometeorological station (e.g., solar radiation, temperature and relative humidity) is presented. Then the error propagation analysis is made for net radiation and for reference evapotranspiration. Data from the Raimat weather station, which is located in the Catalonia region of Spain, are used to illustrate the error relationships. The results show that temperature, relative humidity and cloud cover errors have little effect on the net radiation or reference evapotranspiration. A 5°C error in estimating surface temperature leads to errors as big as 30 W m −2 at high temperature. A 4% solar radiation (R s ) error can cause a net radiation error as big as 26 W m −2 when R s ≈ 1000 W m −2 . However, the error is less when cloud cover is calculated as a function of the solar radiation. The absolute error in reference evapotranspiration (ET o ) equals the product of the net radiation error and the radiation term weighting factor [W = Δ(Δ1+γ)] in the ET o equation. Therefore, the ET o error varies between 65 and 85% of the R n error as air temperature increases from about 20° to 40°C. (author)

  5. Experiments and simulation of a net closing mechanism for tether-net capture of space debris

    Sharf, Inna; Thomsen, Benjamin; Botta, Eleonora M.; Misra, Arun K.

    2017-10-01

    This research addresses the design and testing of a debris containment system for use in a tether-net approach to space debris removal. The tether-net active debris removal involves the ejection of a net from a spacecraft by applying impulses to masses on the net, subsequent expansion of the net, the envelopment and capture of the debris target, and the de-orbiting of the debris via a tether to the chaser spacecraft. To ensure a debris removal mission's success, it is important that the debris be successfully captured and then, secured within the net. To this end, we present a concept for a net closing mechanism, which we believe will permit consistently successful debris capture via a simple and unobtrusive design. This net closing system functions by extending the main tether connecting the chaser spacecraft and the net vertex to the perimeter and around the perimeter of the net, allowing the tether to actuate closure of the net in a manner similar to a cinch cord. A particular embodiment of the design in a laboratory test-bed is described: the test-bed itself is comprised of a scaled-down tether-net, a supporting frame and a mock-up debris. Experiments conducted with the facility demonstrate the practicality of the net closing system. A model of the net closure concept has been integrated into the previously developed dynamics simulator of the chaser/tether-net/debris system. Simulations under tether tensioning conditions demonstrate the effectiveness of the closure concept for debris containment, in the gravity-free environment of space, for a realistic debris target. The on-ground experimental test-bed is also used to showcase its utility for validating the dynamics simulation of the net deployment, and a full-scale automated setup would make possible a range of validation studies of other aspects of a tether-net debris capture mission.

  6. Simulação do saldo de radiação na Serra da Mantiqueira Simulation of net radiation in the Mantiqueira mountain

    Pabricio M. O. Lopes

    2013-07-01

    Full Text Available A influência do desmatamento da Mata Atlântica sobre o microclima da Serra da Mantiqueira ainda não é totalmente compreendida. Para conhecer as consequências do desmatamento sobre o clima serrano é necessário realizar estudos sobre o balanço de radiação na superfície. A falta de dados possibilita conjugar imagens de satélite com dados meteorológicos em um Sistema de Informação Geográfica na determinação do balanço de radiação. O presente estudo teve por objetivo avaliar o modelo MTCLIM em dias de céu claro ou nublado para simular o balanço de radiação na Serra da Mantiqueira, divisa entre os estados de São Paulo, Minas Gerais e Rio de Janeiro, Brasil. Imagens diárias, semanais e dezesseis dias do sensor MODIS disponíveis em 2003 foram utilizadas em rotinas específicas do MTCLIM. Alvos específicos foram selecionados para avaliar o comportamento do balanço de radiação. Observou-se que o balanço de radiação acompanhou a topografia local e é influenciado pelo tipo de uso da terra. Conclui-se que a temperatura da superfície contribui para aumentar a temperatura do ar implicando em diminuição do balanço de radiação sobre pastagem. O modelo MTCLIM demonstrou boa correlação para a temperatura do ar (R² = 0,82 e para a radiação solar global (R² = 0,71.The influence of deforestation of the Atlantic Forest on the microclimate of the mountain Mantiqueira is not yet fully understood. To understand the consequences of deforestation on the highland climate research is needed about the surface radiation balance. The lack of data allows combining satellite images with meteorological data in a Geographic Information System in determining the radiation balance. The study aimed to evaluate the MTCLIM model in cloudless days or cloudy sky and simulate the radiation balance in the Mantiqueira mountain, between São Paulo, Minas Gerais and Rio de Janeiro, Brazil. Daily images, weekly and sixteen days MODIS available in

  7. RadNet (Environmental Radiation Ambient Monitoring System)

    U.S. Environmental Protection Agency — RadNet, formerly Environmental Radiation Ambient Monitoring System (ERAMS), is a national network of monitoring stations that regularly collect air, precipitation,...

  8. Estimation of daily net radiation from synoptic meteorological data

    Lee, B.W.; Myung, E.J.; Kim, B.C.

    1991-01-01

    Five models for net radiation estimation reported by Linacre (1968), Berljand(1956), Nakayama et al. (1983), Chang (1970) and Doorenbos et al. (1977) were tested for the adaptability to Korea. A new model with effective longwave radiation term parameterized by air temperature, solar radiation and vapor pressure was formulated and tested for its accuracy. Above five models with original parameter values showed large absolute mean deviations ranging from 0.86 to 1.64 MJ/m 2 /day. The parameters of the above five models were reestimated by using net radiation and meteorological elements measured in Suwon, Korea

  9. CPN Tools for Editing, Simulating, and Analysing Coloured Petri Nets

    Ratzer, Anne Vinter; Wells, Lisa Marie; Lassen, Henry Michael

    2003-01-01

    elements. The tool features incremental syntax checking and code generation which take place while a net is being constructed. A fast simulator efficiently handles both untimed and timed nets. Full and partial state spaces can be generated and analysed, and a standard state space report contains...

  10. Radiation in Particle Simulations

    More, R.; Graziani, F.; Glosli, J.; Surh, M.

    2010-01-01

    Hot dense radiative (HDR) plasmas common to Inertial Confinement Fusion (ICF) and stellar interiors have high temperature (a few hundred eV to tens of keV), high density (tens to hundreds of g/cc) and high pressure (hundreds of megabars to thousands of gigabars). Typically, such plasmas undergo collisional, radiative, atomic and possibly thermonuclear processes. In order to describe HDR plasmas, computational physicists in ICF and astrophysics use atomic-scale microphysical models implemented in various simulation codes. Experimental validation of the models used to describe HDR plasmas are difficult to perform. Direct Numerical Simulation (DNS) of the many-body interactions of plasmas is a promising approach to model validation but, previous work either relies on the collisionless approximation or ignores radiation. We present four methods that attempt a new numerical simulation technique to address a currently unsolved problem: the extension of molecular dynamics to collisional plasmas including emission and absorption of radiation. The first method applies the Lienard-Weichert solution of Maxwell's equations for a classical particle whose motion is assumed to be known. The second method expands the electromagnetic field in normal modes (planewaves in a box with periodic boundary-conditions) and solves the equation for wave amplitudes coupled to the particle motion. The third method is a hybrid molecular dynamics/Monte Carlo (MD/MC) method which calculates radiation emitted or absorbed by electron-ion pairs during close collisions. The fourth method is a generalization of the third method to include small clusters of particles emitting radiation during close encounters: one electron simultaneously hitting two ions, two electrons simultaneously hitting one ion, etc. This approach is inspired by the virial expansion method of equilibrium statistical mechanics. Using a combination of these methods we believe it is possible to do atomic-scale particle simulations of

  11. Estimating net short-wave radiation with the Bellani pyranometer

    Bernier, Y.; Plamondon, A.P.

    1983-01-01

    Two methods were developed by which daily net short-wave radiation (K∗) can be evaluated from Bellani pyranometer readings. The first method involves a simple regression equation. The second method uses a physical approach taking into account the effect of the Bellani's geometry on its response to direct and diffuse radiation throughout the day. Both methods, when tested on experimental data, tended to underestimate the measured K∗, the regression approach exhibiting a higher variance of the error [fr

  12. CPN Tools for Editing, Simulating, and Analysing Coloured Petri Nets

    Ratzer, Anne Vinter; Wells, Lisa Marie; Lassen, Henry Michael

    2003-01-01

    CPN Tools is a tool for editing, simulating and analysing Coloured Petri Nets. The GUI is based on advanced interaction techniques, such as toolglasses, marking menus, and bi-manual interaction. Feedback facilities provide contextual error messages and indicate dependency relationships between ne...... information such as boundedness properties and liveness properties. The functionality of the simulation engine and state space facilities are similar to the corresponding components in Design/CPN, which is a widespread tool for Coloured Petri Nets.......CPN Tools is a tool for editing, simulating and analysing Coloured Petri Nets. The GUI is based on advanced interaction techniques, such as toolglasses, marking menus, and bi-manual interaction. Feedback facilities provide contextual error messages and indicate dependency relationships between net...

  13. PNet: A Python Library for Petri Net Modeling and Simulation

    Zhu En Chay; Bing Feng Goh; Maurice HT Ling

    2016-01-01

    Petri Net is a formalism to describe changes between 2 or more states across discrete time and has been used to model many systems. We present PNet – a pure Python library for Petri Net modeling and simulation in Python programming language. The design of PNet focuses on reducing the learning curve needed to define a Petri Net by using a text-based language rather than programming constructs to define transition rules. Complex transition rules can be refined as regular Python functions. To de...

  14. Estimating shortwave solar radiation using net radiation and meteorological measurements

    Shortwave radiation has a wide variety of uses in land-atmosphere interactions research. Actual evapotranspiration estimation that involves stomatal conductance models like Jarvis and Ball-Berry require shortwave radiation to estimate photon flux density. However, in most weather stations, shortwave...

  15. NET PRESENT VALUE SIMULATING WITH A SPREADSHEET

    Maria CONSTANTINESCU

    2010-01-01

    Full Text Available Decision making has always been a difficult process, based on various combinations if objectivity (when scientific tools were used and subjectivity (considering that decisions are finally made by people, with their strengths and weaknesses. The IT revolution has also reached the areas of management and decision making, helping managers make better and more informed decisions by providing them with a variety of tools, from the personal computers to the specialized software. Most simulations are performed in a spreadsheet, because the number of calculations required soon overwhelms human capability.

  16. RadNet: Open network protocol for radiation data

    Rees, B.; Olson, K.; Beckes-Talcott, J.; Kadner, S.; Wenderlich, T.; Hoy, M.; Doyle, W.; Koskelo, M.

    1998-01-01

    Safeguards instrumentation is increasingly being incorporated into remote monitoring applications. In the past, vendors of radiation monitoring instruments typically provided the tools for uploading the monitoring data to a host. However, the proprietary nature of communication protocols lends itself to increased computer support needs and increased installation expenses. As a result, a working group of suppliers and customers of radiation monitoring instruments defined an open network protocol for transferring packets on a local area network from radiation monitoring equipment to network hosts. The protocol was termed RadNet. While it is now primarily used for health physics instruments, RadNet's flexibility and strength make it ideal for remote monitoring of nuclear materials. The incorporation of standard, open protocols ensures that future work will not render present work obsolete; because RadNet utilizes standard Internet protocols, and is itself a non-proprietary standard. The use of industry standards also simplifies the development and implementation of ancillary services, e.g. E-main generation or even pager systems

  17. Numerical simulation of the knotted nylon netting panel

    Li Yuwei

    2016-01-01

    Full Text Available A piece of netting, consists of the 8 8 meshes, fixed on a square frame, was simulated and the tensions and their distribution, the positions of knots and netting shape were calculated by means of MATLAB in computer. The dynamic mathematic model was developed based on lumped mass method, the netting was treated as spring-mass system, the Runge-Kutta fifth-order and sixth-order method was used to solve the differential equations for every step, then the displacement and tension of each mass point were obtained. For verify this model, the tests have been carried out in a flume tank. The results of the numerical simulation fully agreed with the experiments.

  18. Particle Tracking and Simulation on the .NET Framework

    Nishimura, Hiroshi; Scarvie, Tom

    2006-01-01

    Particle tracking and simulation studies are becoming increasingly complex. In addition to the use of more sophisticated graphics, interactive scripting is becoming popular. Compatibility with different control systems requires network and database capabilities. It is not a trivial task to fulfill all the various requirements without sacrificing runtime performance. We evaluated the effectiveness of the .NET framework by converting a C++ simulation code to C. The portability to other platforms is mentioned in terms of Mono

  19. CPN Tools-Assisted Simulation and Verification of Nested Petri Nets

    L. W. Dworza´nski

    2012-01-01

    Full Text Available Nested Petri nets (NP-nets are an extension of Petri net formalism within the “netswithin-nets” approach, when tokens in a marking are Petri nets, which have an autonomous behavior and are synchronized with the system net. The formalism of NP-nets allows modeling multi-level multi-agent systems with dynamic structure in a natural way. Currently, there is no tool for supporting NP-nets simulation and analysis. The paper proposes the translation of NP-nets into Colored Petri nets and the use of CPN Tools as a virtual machine for NP-nets modeling, simulation and automatic verification.

  20. A dynamic simulation to study NET in-vessel handling operations

    Fung, P.T.F.

    1989-01-01

    The inspection, maintenance and repair of the Next European Torus (NET) fusion machine will require the extensive use of remote handling equipment to minimise the human exposure to the high radiation environment. The use of efficient manipulators will reduce the NET downtime by reducing the preparation time for entry into the controlled area and by performing the task with reasonable area and by performing the task with reasonable dexterity and speed, consistent with safety. A high fidelity simulation is a valuable tool to assist in the manipulator design, operations, trajectory planning, parameter optimisation and system verification. A manipulator simulation package called ASAD was originally developed by Spar for space manipulator applications. It is now being adapted to simulate the in-Vessel HandlingUnit for the NET program. This terestrial version of ASAD has been name ASAD - T. Spar, through the services of the Canadian Fusion Fuels Technology Project, is under contract to the NET program for the performance of this activity. This paper describes the capabillities and underlying assumptions of ASAD - T, aling with description of the simulation development of the NET in-vessel manipulator. (author). 4 refs.; 7 figs

  1. Development of space simulation / net-laboratory system

    Usui, H.; Matsumoto, H.; Ogino, T.; Fujimoto, M.; Omura, Y.; Okada, M.; Ueda, H. O.; Murata, T.; Kamide, Y.; Shinagawa, H.; Watanabe, S.; Machida, S.; Hada, T.

    A research project for the development of space simulation / net-laboratory system was approved by Japan Science and Technology Corporation (JST) in the category of Research and Development for Applying Advanced Computational Science and Technology(ACT-JST) in 2000. This research project, which continues for three years, is a collaboration with an astrophysical simulation group as well as other space simulation groups which use MHD and hybrid models. In this project, we develop a proto type of unique simulation system which enables us to perform simulation runs by providing or selecting plasma parameters through Web-based interface on the internet. We are also developing an on-line database system for space simulation from which we will be able to search and extract various information such as simulation method and program, manuals, and typical simulation results in graphic or ascii format. This unique system will help the simulation beginners to start simulation study without much difficulty or effort, and contribute to the promotion of simulation studies in the STP field. In this presentation, we will report the overview and the current status of the project.

  2. Solar and Net Radiation for Estimating Potential Evaporation from Three Vegetation Canopies

    D.M. Amatya; R.W. Skaggs; G.W. Cheschier; G.P. Fernandez

    2000-01-01

    Solar and net radiation data are frequent/y used in estimating potential evaporation (PE) from various vegetative surfaces needed for water balance and hydrologic modeling studies. Weather parameters such as air temperature, relative humidity, wind speed, solar radiation, and net radiation have been continuously monitored using automated sensors to estimate PE for...

  3. Spectral estimates of net radiation and soil heat flux

    Daughtry, C.S.T.; Kustas, W.P.; Moran, M.S.; Pinter, P.J. Jr.; Jackson, R.D.; Brown, P.W.; Nichols, W.D.; Gay, L.W.

    1990-01-01

    Conventional methods of measuring surface energy balance are point measurements and represent only a small area. Remote sensing offers a potential means of measuring outgoing fluxes over large areas at the spatial resolution of the sensor. The objective of this study was to estimate net radiation (Rn) and soil heat flux (G) using remotely sensed multispectral data acquired from an aircraft over large agricultural fields. Ground-based instruments measured Rn and G at nine locations along the flight lines. Incoming fluxes were also measured by ground-based instruments. Outgoing fluxes were estimated using remotely sensed data. Remote Rn, estimated as the algebraic sum of incoming and outgoing fluxes, slightly underestimated Rn measured by the ground-based net radiometers. The mean absolute errors for remote Rn minus measured Rn were less than 7%. Remote G, estimated as a function of a spectral vegetation index and remote Rn, slightly overestimated measured G; however, the mean absolute error for remote G was 13%. Some of the differences between measured and remote values of Rn and G are associated with differences in instrument designs and measurement techniques. The root mean square error for available energy (Rn - G) was 12%. Thus, methods using both ground-based and remotely sensed data can provide reliable estimates of the available energy which can be partitioned into sensible and latent heat under non advective conditions

  4. Analysis of solar radiation transfer: A method to estimate the porosity of a plastic shading net

    Abdel-Ghany, A.M.; Al-Helal, I.M.

    2011-01-01

    Plastic nets with opaque threads are frequently used for shading agricultural structures under high solar radiation conditions. A parameter that is often used to define a net is the net porosity (Π). Value of Π is usually estimated by one of three methods: image processing, direct beam transmittance, or solar radiation balance (hereafter radiation balance). Image processing is a rather slow process because it requires scanning the net sample at high resolution. The direct beam transmittance and radiation balance methods greatly overestimate Π because some of the solar radiation incident on the thread surfaces is forward scattered and add a considerable amount of radiation to that transmitted from the net pores directly. In this study, the radiation balance method was modified to estimate Π precisely. The amount of solar radiation scattered forward on the thread surfaces was estimated separately. Thus, the un-scattered solar radiation transmitted from the net pores directly, which describes the net porosity, Π could be estimated. This method, in addition to the image processing and the direct beam transmittance methods were used to estimate Π for different types of nets that are commonly used for shading structures in summer. Values of Π estimated by using the proposed method were in good accordance with those measured by the image processing method at a resolution of 4800 dpi. The direct beam transmittance and the radiation balance methods resulted in overestimation errors in the values of Π. This error strongly depends on the color of the net. The estimated errors were +14% for a green net and +37% for a white net when using the radiation balance method, and were +16% and +38%, respectively, when using the direct beam transmittance method. In the image processing method, a resolution of 2400 dpi is sufficient to estimate Π precisely and the higher resolutions showed no significant effect on the value of Π.

  5. Dynamic simulation of the NET In-Vessel Handling Unit

    Reim, J.

    1991-01-01

    During the conceptual design phase of the Next European Torus (NET) a large remote maintenance transporter system, the In-Vessel Handling Unit (IVHU), is being developed. It consists of an articulated boom with four rotational joints, which is mounted on a carrier outside the vessel. This boom will be able to carry master-slave manipulators or special work units. The engineering design is supported by dynamic computations. Main topics of the dynamic simulation are the evaluation of IVHU performance, selection and optimisation of the actuator design and of the control algorithms. This simulation task requires full three-dimensional modelling regarding structural elasticity and non-linear actuator dynamics. The Multibody dynamics of the transporter system are modelled with a commerical analysis package. Elastic links and a precise dynamic actuator model are introduced by applied forces, spring elements and differential equations. The actuator model comprises electric motors, gears and linear control algorithms. Non-linear effects which have an influence on control stability and accuracy are taken into account. Most important effects are backlash and static friction. The simulations concentrate on test and optimisation of the control layout and performance studies for critical remote handling tasks. Simulations for control layout and critical remote maintenance tasks correspond to the design objectives of the transporter system. (orig.)

  6. Net radiative forcing and air quality responses to regional CO emission reductions

    M. M. Fry

    2013-05-01

    Full Text Available Carbon monoxide (CO emissions influence global and regional air quality and global climate change by affecting atmospheric oxidants and secondary species. We simulate the influence of halving anthropogenic CO emissions globally and individually from 10 regions on surface and tropospheric ozone, methane, and aerosol concentrations using a global chemical transport model (MOZART-4 for the year 2005. Net radiative forcing (RF is then estimated using the GFDL (Geophysical Fluid Dynamics Laboratory standalone radiative transfer model. We estimate that halving global CO emissions decreases global annual average concentrations of surface ozone by 0.45 ppbv, tropospheric methane by 73 ppbv, and global annual net RF by 36.1 mW m−2, nearly equal to the sum of changes from the 10 regional reductions. Global annual net RF per unit change in emissions and the 100 yr global warming potential (GWP100 are estimated as −0.124 mW m−2 (Tg CO−1 and 1.34, respectively, for the global CO reduction, and ranging from −0.115 to −0.131 mW m−2 (Tg CO−1 and 1.26 to 1.44 across 10 regions, with the greatest sensitivities for regions in the tropics. The net RF distributions show widespread cooling corresponding to the O3 and CH4 decreases, and localized positive and negative net RFs due to changes in aerosols. The strongest annual net RF impacts occur within the tropics (28° S–28° N followed by the northern midlatitudes (28° N–60° N, independent of reduction region, while the greatest changes in surface CO and ozone concentrations occur within the reduction region. Some regional reductions strongly influence the air quality in other regions, such as East Asia, which has an impact on US surface ozone that is 93% of that from North America. Changes in the transport of CO and downwind ozone production clearly exceed the direct export of ozone from each reduction region. The small variation in CO GWPs among world regions suggests that future international

  7. Global Surface Net-Radiation at 5 km from MODIS Terra

    Manish Verma

    2016-09-01

    Full Text Available Reliable and fine resolution estimates of surface net-radiation are required for estimating latent and sensible heat fluxes between the land surface and the atmosphere. However, currently, fine resolution estimates of net-radiation are not available and consequently it is challenging to develop multi-year estimates of evapotranspiration at scales that can capture land surface heterogeneity and are relevant for policy and decision-making. We developed and evaluated a global net-radiation product at 5 km and 8-day resolution by combining mutually consistent atmosphere and land data from the Moderate Resolution Imaging Spectroradiometer (MODIS on board Terra. Comparison with net-radiation measurements from 154 globally distributed sites (414 site-years from the FLUXNET and Surface Radiation budget network (SURFRAD showed that the net-radiation product agreed well with measurements across seasons and climate types in the extratropics (Wilmott’s index ranged from 0.74 for boreal to 0.63 for Mediterranean sites. Mean absolute deviation between the MODIS and measured net-radiation ranged from 38.0 ± 1.8 W∙m−2 in boreal to 72.0 ± 4.1 W∙m−2 in the tropical climates. The mean bias was small and constituted only 11%, 0.7%, 8.4%, 4.2%, 13.3%, and 5.4% of the mean absolute error in daytime net-radiation in boreal, Mediterranean, temperate-continental, temperate, semi-arid, and tropical climate, respectively. To assess the accuracy of the broader spatiotemporal patterns, we upscaled error-quantified MODIS net-radiation and compared it with the net-radiation estimates from the coarse spatial (1° × 1° but high temporal resolution gridded net-radiation product from the Clouds and Earth’s Radiant Energy System (CERES. Our estimates agreed closely with the net-radiation estimates from the CERES. Difference between the two was less than 10 W·m−2 in 94% of the total land area. MODIS net-radiation product will be a valuable resource for the

  8. Comparisons of solar radiation interception, albedo and net radiation as influenced by row orientations of crops

    Baten, Md.A.; Kon, H.

    1997-01-01

    Field experiments were conducted on soybean (Glycin max L.) in summer and potato (Solanum tuberosum L.) in autumn to evaluate the effect of row orientations of crops on some selected micro meteorological factors during 1994 and 1995. The intercepted solar radiation was the largest in the plants growing in bidirection in summer and it exhibited intermediate trend in autumn as compared to E-W or N-S row orientations. In summer, penetrated solar radiation between two plants and near the stem base of a N-S row was larger than that of E-W row. While in autumn, the observed solar radiation between two plants and near the stem base of a E-W row was markedly larger than that of N-S row. The area weighted mean of penetrated solar radiation was larger in E-W soybean rows but lower in potato rows as compared to N-S row orientations. Soil surface temperature between N-S potato rows was larger than that of E-W potato rows and the upper canopy surface temperature of potato was larger in E-W rows as compared to N-S rows. Net radiation observed over E-W potato rows was larger as compared to N-S potato rows but net radiation measured under canopy of E-W potato rows was smaller than that of in N-S rows. Net radiation measured over N-S soybean rows was larger than that of E-W soybean rows and it was smaller between N-S soybean rows when measured under canopy as compared to E-W rows. The albedo observed over potato was larger over E-W rows as compared to N-S rows. Albedos over soybean canopy showed opposite trend with the albedos observed over potato canopy. It was larger over N-S rows as compared to E-W rows. High harvest index was associated with larger interception of radiation. (author)

  9. Estimation of absorbed photosynthetically active radiation and vegetation net production efficiency using satellite data

    Hanan, N.P.; Prince, S.D.; Begue, A.

    1995-01-01

    The amount of photosynthetically active radiation (PAR) absorbed by green vegetation is an important determinant of photosynthesis and growth. Methods for the estimation of fractional absorption of PAR (iff PAR ) for areas greater than 1 km 2 using satellite data are discussed, and are applied to sites in the Sahel that have a sparse herb layer and tree cover of less than 5%. Using harvest measurements of seasonal net production, net production efficiencies are calculated. Variation in estimates of seasonal PAR absorption (APAR) caused by the atmospheric correction method and relationship between surface reflectances and iff PAR is considered. The use of maximum value composites of satellite NDVI to reduce the effect of the atmosphere is shown to produce inaccurate APAR estimates. In this data set, however, atmospheric correction using average optical depths was found to give good approximations of the fully corrected data. A simulation of canopy radiative transfer using the SAIL model was used to derive a relationship between canopy NDVI and iff PAR . Seasonal APAR estimates assuming a 1:1 relationship between iff PAR and NDVI overestimated the SAIL modeled results by up to 260%. The use of a modified 1:1 relationship, where iff PAR was assumed to be linearly related to NDVI scaled between minimum (soil) and maximum (infinite canopy) values, underestimated the SAIL modeled results by up to 35%. Estimated net production efficiencies (ϵ n , dry matter per unit APAR) fell in the range 0.12–1.61 g MJ −1 for above ground production, and in the range 0.16–1.88 g MJ −1 for total production. Sites with lower rainfall had reduced efficiencies, probably caused by physiological constraints on photosynthesis during dry conditions. (author)

  10. TAO/TRITON, RAMA, and PIRATA Buoys, Quarterly, 2000-present, Net Longwave Radiation

    National Oceanic and Atmospheric Administration, Department of Commerce — This dataset has quarterly Net Longwave Radiation data from the TAO/TRITON (Pacific Ocean, https://www.pmel.noaa.gov/gtmba/ ), RAMA (Indian Ocean,...

  11. TAO/TRITON, RAMA, and PIRATA Buoys, Monthly, 1991-present, Net Shortwave Radiation

    National Oceanic and Atmospheric Administration, Department of Commerce — This dataset has monthly Net Shortwave Radiation data from the TAO/TRITON (Pacific Ocean, https://www.pmel.noaa.gov/gtmba/ ), RAMA (Indian Ocean,...

  12. TAO/TRITON, RAMA, and PIRATA Buoys, Daily, 2000-present, Net Longwave Radiation

    National Oceanic and Atmospheric Administration, Department of Commerce — This dataset has daily Net Longwave Radiation data from the TAO/TRITON (Pacific Ocean, https://www.pmel.noaa.gov/gtmba/ ), RAMA (Indian Ocean,...

  13. TAO/TRITON, RAMA, and PIRATA Buoys, 5-Day, 2000-present, Net Longwave Radiation

    National Oceanic and Atmospheric Administration, Department of Commerce — This dataset has 5-day Net Longwave Radiation data from the TAO/TRITON (Pacific Ocean, https://www.pmel.noaa.gov/gtmba/ ), RAMA (Indian Ocean,...

  14. Evaluation of a model to Simulate Net Radiation Over a Vineyar cv. Cabernet Sauvignon Evaluación de un Modelo para Simular el Flujo de Radiación Neta Sobre un Viñedo cv. Cabernet Sauvignon

    Marcos Carrasco

    2008-06-01

    Full Text Available Net radiation (Rn is the main energy balance component controlling evaporation and transpiration processes. In this regard, this study evaluated two models to estimate Rno above a commercial vineyard (Vitis vinifera cv. Cabernet Sauvignon located in Pencahue Valley, Maule Region (35º22’ S; 71°47’ Wl; 75 m.a.s.l.. An automatic meteorological station (AMS was installed in the central part of the vineyard and used to measure Rn, solar radiation (Rsi, air temperature (Ta, canopy temperature (Tf and relative humidity (RH. On a 30 min interval, results indicated that model Rne1 (assuming Ta ≠ Tf and model Rne2 (assuming Ta = Tf were able to estimate Rn with a mean absolute error (MAE of less than 40 W m-2 and root mean square error (RMSE of less than 61 W m-2. On daily intervals, the two models estimated Rno with MAE and RMSE values of less than 1.68 and 1.75 MJ m-2 d-1, respectively. In global terms, the models presented errors below 9 and 11% on 30 min and daily intervals, respectively. Furthermore, this study indicated that the incorporation of canopy temperature did not improve the Rno estimation substantially, in spite of having a temperature gradient (dT = Tf - Ta between -3 and to 4ºC. These results suggest that an Rne2 model could be used to estimate Rno using Rsi, Ta and RH measurements.El flujo de radiación neta (Rn es el principal componente del balance de energía que determina los procesos de evaporación y transpiración. En este contexto, este estudio evaluó dos modelos para estimar Rno sobre un viñedo (Vitis vinifera L. cv. Cabernet Sauvignon comercial ubicado en el Valle de Pencahue, Región del Maule (35º22’ S; 71º47’ Oeste; 75 m.s.n.m.. Para esto, se ubicó una estación meteorológica automática (AME en la parte central del viñedo para medir Rn, radiación solar (Rsi, temperatura del aire (Ta, temperatura del dosel (Tf y humedad relativa (HR. En intervalos de tiempo de 30 min, los resultados indicaron que el

  15. Simulation of the chemical stage in water radiolysis with the help of Continuous Petri nets

    Barilla, J.; Lokajíček, M.V.; Pisaková, H.; Simr, P.

    2014-01-01

    The final biological effect of ionizing particles may be influenced often strongly by some chemical substances present in cells during irradiation by low-LET radiation. It may occur during the chemical stage of the given process, due to chemical reactions of radicals running in the given process. However, the whole chemical process may be hardly described sufficiently with the help of the usual approach based on the deterministic diffusion-kinetic computations and the stochastic Monte-Carlo simulations. We have proposed already earlier a model describing the processes (i.e., the combined effect of cluster diffusion and chemical reactions) running in individual radical clusters that might be responsible for corresponding damages of DNA molecules (i.e., formation of DSBs). Now a further generalization of the given model (using Continuous Petri nets) will be presented that makes it possible to characterize more detailed behavior of individual radicals in corresponding clusters, which might be useful especially for low-LET radiation when individual radical clusters meet a DNA molecule at different time intervals after their formation; the decreasing presence of individual radicals in corresponding clusters being established. In this paper we shall focus on the design of the corresponding mathematical model and its application; the comparison of corresponding results with experimental data obtained in the case of deoxygenated system will be presented. - Highlights: • Creation of the mathematical model. • Realization of the model with the help of Continuous Petri nets. • Obtain the time dependence of changes in the concentration of radicals

  16. Can climate sensitivity be estimated from short-term relationships of top-of-atmosphere net radiation and surface temperature?

    Lin Bing; Min Qilong; Sun Wenbo; Hu Yongxiang; Fan, Tai-Fang

    2011-01-01

    Increasing the knowledge in climate radiative feedbacks is critical for current climate studies. This work focuses on short-term relationships between global mean surface temperature and top-of-atmosphere (TOA) net radiation. The relationships may be used to characterize the climate feedback as suggested by some recent studies. As those recent studies, an energy balance model with ocean mixed layer and both radiative and non-radiative heat sources is used here. The significant improvement of current model is that climate system memories are considered. Based on model simulations, short-term relationship between global mean surface temperature and TOA net radiation (or the linear striation feature as suggested by previous studies) might represent climate feedbacks when the system had no memories. However, climate systems with the same short-term feedbacks but different memories would have a similar linear striation feature. This linear striation feature reflects only fast components of climate feedbacks and may not represent the total climate feedback even when the memory length of climate systems is minimal. The potential errors in the use of short-term relationships in estimations of climate sensitivity could be big. In short time scales, fast climate processes may overwhelm long-term climate feedbacks. Thus, the climate radiative feedback parameter obtained from short-term data may not provide a reliable estimate of climate sensitivity. This result also suggests that long-term observations of global surface temperature and TOA radiation are critical in the understanding of climate feedbacks and sensitivities.

  17. Observation and simulation of net primary productivity in Qilian Mountain, western China.

    Zhou, Y; Zhu, Q; Chen, J M; Wang, Y Q; Liu, J; Sun, R; Tang, S

    2007-11-01

    We modeled net primary productivity (NPP) at high spatial resolution using an advanced spaceborne thermal emission and reflection radiometer (ASTER) image of a Qilian Mountain study area using the boreal ecosystem productivity simulator (BEPS). Two key driving variables of the model, leaf area index (LAI) and land cover type, were derived from ASTER and moderate resolution imaging spectroradiometer (MODIS) data. Other spatially explicit inputs included daily meteorological data (radiation, precipitation, temperature, humidity), available soil water holding capacity (AWC), and forest biomass. NPP was estimated for coniferous forests and other land cover types in the study area. The result showed that NPP of coniferous forests in the study area was about 4.4 tCha(-1)y(-1). The correlation coefficient between the modeled NPP and ground measurements was 0.84, with a mean relative error of about 13.9%.

  18. Assessment of the methods for determining net radiation at different time-scales of meteorological variables

    Ni An

    2017-04-01

    Full Text Available When modeling the soil/atmosphere interaction, it is of paramount importance to determine the net radiation flux. There are two common calculation methods for this purpose. Method 1 relies on use of air temperature, while Method 2 relies on use of both air and soil temperatures. Nowadays, there has been no consensus on the application of these two methods. In this study, the half-hourly data of solar radiation recorded at an experimental embankment are used to calculate the net radiation and long-wave radiation at different time-scales (half-hourly, hourly, and daily using the two methods. The results show that, compared with Method 2 which has been widely adopted in agronomical, geotechnical and geo-environmental applications, Method 1 is more feasible for its simplicity and accuracy at shorter time-scale. Moreover, in case of longer time-scale, daily for instance, less variations of net radiation and long-wave radiation are obtained, suggesting that no detailed soil temperature variations can be obtained. In other words, shorter time-scales are preferred in determining net radiation flux.

  19. Simulating the hydrodynamic response of a floater–net system in current and waves

    Chen, Hao; Christensen, Erik Damgaard

    2018-01-01

    We present a novel numerical model for simulating current and wave interaction with a floater–net system. The main contribution of the paper is the integration of the floater motion and the fluid–structure interaction analysis of the net structure in the same modelling framework via the computati...

  20. SIMULATION OF NET INFILTRATION FOR MODERN AND POTENTIAL FUTURE CLIMATES

    J.A. Heveal

    2000-01-01

    This Analysis/Model Report (AMR) describes enhancements made to the infiltration model documented in Flint et al. (1996) and documents an analysis using the enhanced model to generate spatial and temporal distributions over a model domain encompassing the Yucca Mountain site, Nevada. Net infiltration is the component of infiltrated precipitation, snowmelt, or surface water run-on that has percolated below the zone of evapotranspiration as defined by the depth of the effective root zone, the average depth below the ground surface (at a given location) from which water is removed by evapotranspiration. The estimates of net infiltration are used for defining the upper boundary condition for the site-scale 3-dimensional Unsaturated-Zone Ground Water Flow and Transport (UZ flow and transport) Model (CRWMS M and O 2000a). The UZ flow and transport model is one of several process models abstracted by the Total System Performance Assessment model to evaluate expected performance of the potential repository at Yucca Mountain, Nevada, in terms of radionuclide transport (CRWMS M and O 1998). The net-infiltration model is important for assessing potential repository-system performance because output from this model provides the upper boundary condition for the UZ flow and transport model that is used to generate flow fields for evaluating potential radionuclide transport through the unsaturated zone. Estimates of net infiltration are provided as raster-based, 2-dimensional grids of spatially distributed, time-averaged rates for three different climate stages estimated as likely conditions for the next 10,000 years beyond the present. Each climate stage is represented using a lower bound, a mean, and an upper bound climate and corresponding net-infiltration scenario for representing uncertainty in the characterization of daily climate conditions for each climate stage, as well as potential climate variability within each climate stage. The set of nine raster grid maps provide

  1. SIMULATION OF NET INFILTRATION FOR MODERN AND POTENTIAL FUTURE CLIMATES

    J.A. Heveal

    2000-06-16

    This Analysis/Model Report (AMR) describes enhancements made to the infiltration model documented in Flint et al. (1996) and documents an analysis using the enhanced model to generate spatial and temporal distributions over a model domain encompassing the Yucca Mountain site, Nevada. Net infiltration is the component of infiltrated precipitation, snowmelt, or surface water run-on that has percolated below the zone of evapotranspiration as defined by the depth of the effective root zone, the average depth below the ground surface (at a given location) from which water is removed by evapotranspiration. The estimates of net infiltration are used for defining the upper boundary condition for the site-scale 3-dimensional Unsaturated-Zone Ground Water Flow and Transport (UZ flow and transport) Model (CRWMS M&O 2000a). The UZ flow and transport model is one of several process models abstracted by the Total System Performance Assessment model to evaluate expected performance of the potential repository at Yucca Mountain, Nevada, in terms of radionuclide transport (CRWMS M&O 1998). The net-infiltration model is important for assessing potential repository-system performance because output from this model provides the upper boundary condition for the UZ flow and transport model that is used to generate flow fields for evaluating potential radionuclide transport through the unsaturated zone. Estimates of net infiltration are provided as raster-based, 2-dimensional grids of spatially distributed, time-averaged rates for three different climate stages estimated as likely conditions for the next 10,000 years beyond the present. Each climate stage is represented using a lower bound, a mean, and an upper bound climate and corresponding net-infiltration scenario for representing uncertainty in the characterization of daily climate conditions for each climate stage, as well as potential climate variability within each climate stage. The set of nine raster grid maps provide spatially

  2. Fractal characteristics correlation between the solar total radiation and net radiation on the apple tree canopy

    Meng Ping; Zhang Jingsong

    2005-01-01

    The characteristics correlation between solar total radiations(Q) and net radiation(R n) on the apple tree canopy at mainly growth stage in the hilly of Taihang Mountain are analyzed with fractal theory based on regression analysis. The results showed that:1)Q and R n had good liner correlation. The regression function was as the following:R n=0.740 8Q-32.436, which coefficient r is 0.981 1(n=26 279), F cal= 343 665.2 F 0.01 36 277=6.63; 2)The fractal dimension curves of Q and R n both had two no s caling regions, which circumscription time value of the inflexion was 453 and 441 minutes respectively.In the first region, fractal dimensions of Q and R n was 1.112 6, 1.131 9 respectively,and 1.913 6@@@ 1.883 4 in the second region.Those information showed that fractal characteristics of Q and R n is similar. So R n can be calculated with Q on the apple tree canopy

  3. Effect of gamma radiation on chlorophylls contents, net photosynthesis and respiration of chlorella pyrenoidosa

    Fernandez Gonzalez, J.; Martin Moreno, C.

    1983-01-01

    The effect of five doses of gamma radiation: 10, 100, 500, 1000 and 5000 Gy on chlorophylls content, net photosynthesis and respiration of chlorella pyrenoidosa has been studied. A decrease in chlorophylls levels is produced after irradiation at 500, 1000 and 5000 Gy, being, at first 'b' chlorophyll affected to a greater extent than 'a' chlorophyll. Net photosynthesis and respiration decline throughout the time of the observations after irradiation, this depressing effect being much more remarkable for the first one. Net photosynthesis inhibition levels of about 30% have got only five hours post irradiation at a dose of 5000 Gy. (author)

  4. Net-erosion profile model and simulation experiments

    Sagara, Akio

    2001-01-01

    Estimation of net-erosion profile is requisite for evaluating the lifetime of divertor plates under high heat and particle fluxes of fusion plasmas. As a reference in benchmark tests of numerical calculation codes, a self-consistent analytical solution is presented for a simplified divertor condition, wherein the magnetic field line is normal to the target plate and the ionization mean free path of sputtered particles is assumed constant. The primary flux profile of hydrogen and impurities are externally given as well as the return ratio of sputtered atoms to the target. In the direction along the divertor trace, all conditions are uniform. The analytical solution is compared with net-erosion experiments carried out using the Compact Helical System (CHS). The deposition profiles of Ti and O impurities are in very good agreement with the analytical predictions. Recent preliminary results observed on divertor plates in the Large Helical Device (LHD) are briefly presented. (author)

  5. Refining surface net radiation estimates in arid and semi-arid climates of Iran

    Golkar, Foroogh; Rossow, William B.; Sabziparvar, Ali Akbar

    2018-06-01

    Although the downwelling fluxes exhibit space-time scales of dependency on characteristic of atmospheric variations, especially clouds, the upward fluxes and, hence the net radiation, depends on the variation of surface properties, particularly surface skin temperature and albedo. Evapotranspiration at the land surface depends on the properties of that surface and is determined primarily by the net surface radiation, mostly absorbed solar radiation. Thus, relatively high spatial resolution net radiation data are needed for evapotranspiration studies. Moreover, in more arid environments, the diurnal variations of surface (air and skin) temperature can be large so relatively high (sub-daily) time resolution net radiation is also needed. There are a variety of radiation and surface property products available but they differ in accuracy, space-time resolution and information content. This situation motivated the current study to evaluate multiple sources of information to obtain the best net radiation estimate with the highest space-time resolution from ISCCP FD dataset. This study investigates the accuracy of the ISCCP FD and AIRS surface air and skin temperatures, as well as the ISCCP FD and MODIS surface albedos and aerosol optical depths as the leading source of uncertainty in ISCCP FD dataset. The surface air temperatures, 10-cm soil temperatures and surface solar insolation from a number of surface sites are used to judge the best combinations of data products, especially on clear days. The corresponding surface skin temperatures in ISCCP FD, although they are known to be biased somewhat high, disagreed more with AIRS measurements because of the mismatch of spatial resolutions. The effect of spatial resolution on the comparisons was confirmed using the even higher resolution MODIS surface skin temperature values. The agreement of ISCCP FD surface solar insolation with surface measurements is good (within 2.4-9.1%), but the use of MODIS aerosol optical depths as

  6. [Effects of reduced solar radiation on winter wheat flag leaf net photosynthetic rate].

    Zheng, You-Fei; Ni, Yan-Li; Mai, Bo-Ru; Wu, Rong-Jun; Feng, Yan; Sun, Jian; Li, Jian; Xu, Jing-Xin

    2011-06-01

    Taking winter wheat Triticum aestivum L. (cv. Yangmai 13) as test material, a field experiment was conducted in Nanjing City to study the effects of simulated reduced solar radiation on the diurnal variation of winter wheat flag leaf photosynthetic rate and the main affecting factors. Five treatments were installed, i. e., 15% (T15), 20% (T20) , 40% (T40), 60% (T60), and 100% (CK) of total incident solar radiation. Reduced solar irradiance increased the chlorophyll and lutein contents significantly, but decreased the net photosynthetic rate (Pn). Under different solar irradiance, the diurnal variation of Pn had greater difference, and the daily maximum Pn was in the order of CK > T60 > T40 > T 20 > T15. In CK, the Pn exhibited a double peak diurnal curve; while in the other four treatments, the Pn showed a single peak curve, and the peak was lagged behind that of CK. Correlation analysis showed that reduced solar irradiance was the main factor affecting the diurnal variation of Pn, but the physiological parameters also played important roles in determining the diurnal variation of Pn. In treatments T60 and T40, the photosynthesis active radiation (PAR), leaf temperature (T1) , stomatal conductance (Gs) , and transpiration rate (Tr) were significantly positively correlated with Pn, suggesting their positive effects on Pn. The intercellular CO2 concentration (Ci) and stomatal limitation (Ls) had significant negative correlations with Pn in treatments T60 and T40 but significant positive correlations with Pn in treatments T20 and T15, implying that the Ci and Ls had negative (or positive) effects on Pn when the solar irradiance was higher (or lower) than 40% of incident solar irradiance.

  7. Inconsistencies in net radiation estimates from use of several models of instruments in a desert environment

    Kustas, W.P.; Prueger, J.H.; Hipps, L.E.; Hatfield, J.L.; Meek, D.

    1998-01-01

    Studies of surface energy and water balance generally require an accurate estimate of net radiation and its spatial distribution. A project quantifying both short term and seasonal water use of shrub and grass vegetation in the Jornada Experimental Range in New Mexico prompted a study to compare net radiation observations using two types of net radiometers currently being used in research. A set of 12 REBS net radiometers were compared with each other and one Swissteco, over wet and dry surfaces in an arid landscape under clear skies. The set of REBS exhibited significant differences in output over both surfaces. However, they could be cross calibrated to yield values within 10 W m −2 , on average. There was also a significant bias between the REBS and Swissteco over a dry surface, but not over a wet one. The two makes of instrument could be made to agree under the dry conditions by using regression or autoregression techniques. However, the resulting equations would induce bias for the wet surface condition. Thus, it is not possible to cross calibrate these two makes of radiometer over the range of environmental conditions observed. This result indicates that determination of spatial distribution of net radiation over a variable surface should be made with identical instruments which have been cross calibrated. The need still exists for development of a radiometer and calibration procedures which will produce accurate and consistent measurements over a range of surface conditions. (author)

  8. HYPERION NET - a distributed measurement system for monitoring background ionizing radiation

    Saponjic, Dj.; Zigic, A.; Arandjelovic, V.

    2003-01-01

    The distributed measurement system - HYPERION NET, based on the concept of FieldBus technology, has been developed, implemented, and tested as a pilot project, the first WEB enabled on-line networked ionizing radiation monitoring and measurement system. The Net has layered the structure, tree topology, and is based on the Internet infrastructure and TCP/IP communication protocol. The Net's core element is an intelligent GM transmitter, based on GM tube, used for measuring the absorbed dose in air, in the range of 0.087 to 720 μGy/h. The transmitter makes use of an advanced count rate measurement algorithm capable of suppressing the statistical fluctuations of the measured quantity, which significantly improves its measurement performance mailing it suitable for environmental radiation measurements. (author)

  9. Albedo and estimates of net radiation for green beans under polyethylene cover and field conditions

    Souza, J.L. de; Escobedo, J.F.; Tornero, M.T.T.

    1999-01-01

    This paper describes the albedo (r) and estimates of net radiation and global solar irradiance for green beans crop (Phaseolus vulgaris L.), cultivated in greenhouse with cover of polyethylene and field conditions, in Botucatu, SP, Brazil (22° 54' S; 48° 27' W; 850 m). The solar global irradiance (R g ) and solar reflected radiation (R r ) were used to estimate the albedo through the ratio between R r and R g . The diurnal curves of albedo were obtained for days with clear sky and partially cloudy conditions, for different phenological stages of the crop. The albedo ranged with the solar elevation, the environment and the phenological stages. The cloudiness range have almost no influence on the albedo diurnal amount. The estimation of radiation were made by linear regression, using the global solar irradiance (R g ) and net short-waves radiation (R c ) as independent variables. All estimates of radiation showed better adjustment for specific phenological periods compared to the entire crop growing cycle. The net radiation in the greenhouse has been estimated by the global solar irradiance measured at field conditions. (author) [pt

  10. Achieving informed decision-making for net zero energy buildings design using building performance simulation tools

    Attia, S.G.; Gratia, E.; De Herde, A.; Hensen, J.L.M.

    2013-01-01

    Building performance simulation (BPS) is the basis for informed decision-making of Net Zero Energy Buildings (NZEBs) design. This paper aims to investigate the use of building performance simulation tools as a method of informing the design decision of NZEBs. The aim of this study is to evaluate the

  11. Nuclides.net: An integrated environment for computations on radionuclides and their radiation

    Galy, J.; Magill, J.

    2002-01-01

    Full text: The Nuclides.net computational package is of direct interest in the fields of environment monitoring and nuclear forensics. The 'integrated environment' is a suite of computer programs ranging from a powerful user-friendly interface, which allows the user to navigate the nuclide chart and explore the properties of nuclides, to various computational modules for decay calculations, dosimetry and shielding calculations, etc. The main emphasis in Nuclides.net is on nuclear science applications, such as health physics, radioprotection and radiochemistry, rather than nuclear data for which excellent sources already exist. In contrast to the CD-based Nuclides 2000 predecessor, Nuclides.net applications run over the internet on a web server. The user interface to these applications is via a web browser. Information submitted by the user is sent to the appropriate applications resident on the web server. The results of the calculations are returned to the user, again via the browser. The product is aimed at both students and professionals for reference data on radionuclides and computations based on this data using the latest internet technology. It is particularly suitable for educational purposes in the nuclear industry, health physics and radiation protection, nuclear and radiochemistry, nuclear physics, astrophysics, etc. The Nuclides.net software suite contains the following modules/features: a) A new user interface to view the nuclide charts (with zoom features). Additional nuclide charts are based on spin, parity, binding energy etc. b) There are five main applications: (1) 'Decay Engine' for decay calculations of numbers, masses, activities, dose rates, etc. of parent and daughters. (2) 'Dosimetry and Shielding' module allows the calculation of dose rates from both unshielded and shielded point sources. A choice of 10 shield materials is available. (3) 'Virtual Nuclides' allows the user to do decay and dosimetry and shielding calculations on mixtures of

  12. Estimating Net Primary Productivity Beneath Snowpack Using Snowpack Radiative Transfer Modeling and Global Satellite Data

    Barber, D. E.; Peterson, M. C.

    2002-05-01

    Sufficient photosynthetically active radiation (PAR) penetrates snow for plants to grow beneath snowpack during late winter or early spring in tundra ecosystems. During the spring in this ecosystem, the snowpack creates an environment with higher humidity and less variable and milder temperatures than on the snow-free land. Under these conditions, the amount of PAR available is likely to be the limiting factor for plant growth. Current methods for determining net primary productivity (NPP) of tundra ecosystems do not account for this plant growth beneath snowpack, apparently resulting in underestimating plant production there. We are currently in the process of estimating the magnitude of this early growth beneath snow for tundra ecosystems. Our method includes a radiative transfer model that simulates diffuse and direct PAR penetrating snowpack based on downwelling PAR values and snow depth data from global satellite databases. These PAR levels are convolved with plant growth for vegetation that thrives beneath snowpacks, such as lichen. We expect to present the net primary production for Cladonia species (a common Arctic lichen) that has the capability of photosynthesizing at low temperatures beneath snowpack. This method may also be used to study photosynthesis beneath snowpacks in other hardy plants. Lichens are used here as they are common in snow-covered regions, flourish under snowpack, and provide an important food source for tundra herbivores (e.g. caribou). In addition, lichens are common in arctic-alpine environments and our results can be applied to these ecosystems as well. Finally, the NPP of lichen beneath snowpack is relatively well understood compared to other plants, making it ideal vegetation for this first effort at estimating the potential importance of photosynthesis at large scales. We are examining other candidate plants for their photosynthetic potential beneath snowpack at this time; however, little research has been done on this topic. We

  13. Development of a neural net paradigm that predicts simulator sickness

    Allgood, G.O.

    1993-03-01

    A disease exists that affects pilots and aircrew members who use Navy Operational Flight Training Systems. This malady, commonly referred to as simulator sickness and whose symptomatology closely aligns with that of motion sickness, can compromise the use of these systems because of a reduced utilization factor, negative transfer of training, and reduction in combat readiness. A report is submitted that develops an artificial neural network (ANN) and behavioral model that predicts the onset and level of simulator sickness in the pilots and aircrews who sue these systems. It is proposed that the paradigm could be implemented in real time as a biofeedback monitor to reduce the risk to users of these systems. The model captures the neurophysiological impact of use (human-machine interaction) by developing a structure that maps the associative and nonassociative behavioral patterns (learned expectations) and vestibular (otolith and semicircular canals of the inner ear) and tactile interaction, derived from system acceleration profiles, onto an abstract space that predicts simulator sickness for a given training flight.

  14. Biochemical Network Stochastic Simulator (BioNetS: software for stochastic modeling of biochemical networks

    Elston Timothy C

    2004-03-01

    Full Text Available Abstract Background Intrinsic fluctuations due to the stochastic nature of biochemical reactions can have large effects on the response of biochemical networks. This is particularly true for pathways that involve transcriptional regulation, where generally there are two copies of each gene and the number of messenger RNA (mRNA molecules can be small. Therefore, there is a need for computational tools for developing and investigating stochastic models of biochemical networks. Results We have developed the software package Biochemical Network Stochastic Simulator (BioNetS for efficientlyand accurately simulating stochastic models of biochemical networks. BioNetS has a graphical user interface that allows models to be entered in a straightforward manner, and allows the user to specify the type of random variable (discrete or continuous for each chemical species in the network. The discrete variables are simulated using an efficient implementation of the Gillespie algorithm. For the continuous random variables, BioNetS constructs and numerically solvesthe appropriate chemical Langevin equations. The software package has been developed to scale efficiently with network size, thereby allowing large systems to be studied. BioNetS runs as a BioSpice agent and can be downloaded from http://www.biospice.org. BioNetS also can be run as a stand alone package. All the required files are accessible from http://x.amath.unc.edu/BioNetS. Conclusions We have developed BioNetS to be a reliable tool for studying the stochastic dynamics of large biochemical networks. Important features of BioNetS are its ability to handle hybrid models that consist of both continuous and discrete random variables and its ability to model cell growth and division. We have verified the accuracy and efficiency of the numerical methods by considering several test systems.

  15. Effects of topography on simulated net primary productivity at landscape scale.

    Chen, X F; Chen, J M; An, S Q; Ju, W M

    2007-11-01

    Local topography significantly affects spatial variations of climatic variables and soil water movement in complex terrain. Therefore, the distribution and productivity of ecosystems are closely linked to topography. Using a coupled terrestrial carbon and hydrological model (BEPS-TerrainLab model), the topographic effects on the net primary productivity (NPP) are analyzed through four modelling experiments for a 5700 km(2) area in Baohe River basin, Shaanxi Province, northwest of China. The model was able to capture 81% of the variability in NPP estimated from tree rings, with a mean relative error of 3.1%. The average NPP in 2003 for the study area was 741 gCm(-2)yr(-1) from a model run including topographic effects on the distributions of climate variables and lateral flow of ground water. Topography has considerable effect on NPP, which peaks near 1350 m above the sea level. An elevation increase of 100 m above this level reduces the average annual NPP by about 25 gCm(-2). The terrain aspect gives rise to a NPP change of 5% for forests located below 1900 m as a result of its influence on incident solar radiation. For the whole study area, a simulation totally excluding topographic effects on the distributions of climatic variables and ground water movement overestimated the average NPP by 5%.

  16. Validated simulator for space debris removal with nets and other flexible tethers applications

    Gołębiowski, Wojciech; Michalczyk, Rafał; Dyrek, Michał; Battista, Umberto; Wormnes, Kjetil

    2016-12-01

    In the context of active debris removal technologies and preparation activities for the e.Deorbit mission, a simulator for net-shaped elastic bodies dynamics and their interactions with rigid bodies, has been developed. Its main application is to aid net design and test scenarios for space debris deorbitation. The simulator can model all the phases of the debris capturing process: net launch, flight and wrapping around the target. It handles coupled simulation of rigid and flexible bodies dynamics. Flexible bodies were implemented using Cosserat rods model. It allows to simulate flexible threads or wires with elasticity and damping for stretching, bending and torsion. Threads may be combined into structures of any topology, so the software is able to simulate nets, pure tethers, tether bundles, cages, trusses, etc. Full contact dynamics was implemented. Programmatic interaction with simulation is possible - i.e. for control implementation. The underlying model has been experimentally validated and due to significant gravity influence, experiment had to be performed in microgravity conditions. Validation experiment for parabolic flight was a downscaled process of Envisat capturing. The prepacked net was launched towards the satellite model, it expanded, hit the model and wrapped around it. The whole process was recorded with 2 fast stereographic camera sets for full 3D trajectory reconstruction. The trajectories were used to compare net dynamics to respective simulations and then to validate the simulation tool. The experiments were performed on board of a Falcon-20 aircraft, operated by National Research Council in Ottawa, Canada. Validation results show that model reflects phenomenon physics accurately enough, so it may be used for scenario evaluation and mission design purposes. The functionalities of the simulator are described in detail in the paper, as well as its underlying model, sample cases and methodology behind validation. Results are presented and

  17. Single interval longwave radiation scheme based on the net exchanged rate decomposition with bracketing

    Geleyn, J.- F.; Mašek, Jan; Brožková, Radmila; Kuma, P.; Degrauwe, D.; Hello, G.; Pristov, N.

    2017-01-01

    Roč. 143, č. 704 (2017), s. 1313-1335 ISSN 0035-9009 R&D Projects: GA MŠk(CZ) LO1415 Institutional support: RVO:86652079 Keywords : numerical weather prediction * climate models * clouds * parameterization * atmospheres * formulation * absorption * scattering * accurate * database * longwave radiative transfer * broadband approach * idealized optical paths * net exchanged rate decomposition * bracketing * selective intermittency Subject RIV: DG - Athmosphere Sciences, Meteorology OBOR OECD: Meteorology and atmospheric sciences Impact factor: 3.444, year: 2016

  18. A simple formula for the net long-wave radiation flux in the southern Baltic Sea

    Tomasz Zapadka

    2001-09-01

    Full Text Available This paper discusses problems of estimating the net long-wave radiation flux at the sea surface on the basis of easily measurable meteorological quantities (air and sea surface temperatures, near-surface water vapour pressure, cloudiness. Empirical data and existing formulae are compared. Additionally, an improved formula for the southern Baltic region is introduced, with a systematic error of less than 1 W -2 and a statistical error of less than 20 W -2.

  19. Computer simulation of auroral kilometric radiation

    Wagner, J.S.; Tajima, T.; Lee, L.C.; Wu, C.S.

    1983-01-01

    We study the generation of auroral kilometric radiation (AKR) using relativistic, electromagnetic, particle simulations. The AKR source region is modeled by two electron populations in the simulation: a cold (200 eV) Maxwellian component and a hot (5-20 keV) population possessing a loss-cone feature. The loss cone distribution is found to be unstable to the cyclotron maser instability. The fast extraordinary (X-mode) waves dominate the radiation and saturate when resonant particles diffuse into the loss-cone via turbulent scattering of the particles by the amplified X-mode radiation

  20. Use of MODIS Sensor Images Combined with Reanalysis Products to Retrieve Net Radiation in Amazonia

    de Oliveira, Gabriel; Brunsell, Nathaniel A.; Moraes, Elisabete C.; Bertani, Gabriel; dos Santos, Thiago V.; Shimabukuro, Yosio E.; Aragão, Luiz E. O. C.

    2016-01-01

    In the Amazon region, the estimation of radiation fluxes through remote sensing techniques is hindered by the lack of ground measurements required as input in the models, as well as the difficulty to obtain cloud-free images. Here, we assess an approach to estimate net radiation (Rn) and its components under all-sky conditions for the Amazon region through the Surface Energy Balance Algorithm for Land (SEBAL) model utilizing only remote sensing and reanalysis data. The study period comprised six years, between January 2001–December 2006, and images from MODIS sensor aboard the Terra satellite and GLDAS reanalysis products were utilized. The estimates were evaluated with flux tower measurements within the Large-Scale Biosphere-Atmosphere Experiment in Amazonia (LBA) project. Comparison between estimates obtained by the proposed method and observations from LBA towers showed errors between 12.5% and 16.4% and 11.3% and 15.9% for instantaneous and daily Rn, respectively. Our approach was adequate to minimize the problem related to strong cloudiness over the region and allowed to map consistently the spatial distribution of net radiation components in Amazonia. We conclude that the integration of reanalysis products and satellite data, eliminating the need for surface measurements as input model, was a useful proposition for the spatialization of the radiation fluxes in the Amazon region, which may serve as input information needed by algorithms that aim to determine evapotranspiration, the most important component of the Amazon hydrological balance. PMID:27347957

  1. Use of MODIS Sensor Images Combined with Reanalysis Products to Retrieve Net Radiation in Amazonia.

    de Oliveira, Gabriel; Brunsell, Nathaniel A; Moraes, Elisabete C; Bertani, Gabriel; Dos Santos, Thiago V; Shimabukuro, Yosio E; Aragão, Luiz E O C

    2016-06-24

    In the Amazon region, the estimation of radiation fluxes through remote sensing techniques is hindered by the lack of ground measurements required as input in the models, as well as the difficulty to obtain cloud-free images. Here, we assess an approach to estimate net radiation (Rn) and its components under all-sky conditions for the Amazon region through the Surface Energy Balance Algorithm for Land (SEBAL) model utilizing only remote sensing and reanalysis data. The study period comprised six years, between January 2001-December 2006, and images from MODIS sensor aboard the Terra satellite and GLDAS reanalysis products were utilized. The estimates were evaluated with flux tower measurements within the Large-Scale Biosphere-Atmosphere Experiment in Amazonia (LBA) project. Comparison between estimates obtained by the proposed method and observations from LBA towers showed errors between 12.5% and 16.4% and 11.3% and 15.9% for instantaneous and daily Rn, respectively. Our approach was adequate to minimize the problem related to strong cloudiness over the region and allowed to map consistently the spatial distribution of net radiation components in Amazonia. We conclude that the integration of reanalysis products and satellite data, eliminating the need for surface measurements as input model, was a useful proposition for the spatialization of the radiation fluxes in the Amazon region, which may serve as input information needed by algorithms that aim to determine evapotranspiration, the most important component of the Amazon hydrological balance.

  2. Modeling and Simulation of Multi-scale Environmental Systems with Generalized Hybrid Petri Nets

    Mostafa eHerajy

    2015-07-01

    Full Text Available Predicting and studying the dynamics and properties of environmental systems necessitates the construction and simulation of mathematical models entailing different levels of complexities. Such type of computational experiments often require the combination of discrete and continuous variables as well as processes operating at different time scales. Furthermore, the iterative steps of constructing and analyzing environmental models might involve researchers with different background. Hybrid Petri nets may contribute in overcoming such challenges as they facilitate the implementation of systems integrating discrete and continuous dynamics. Additionally, the visual depiction of model components will inevitably help to bridge the gap between scientists with distinct expertise working on the same problem. Thus, modeling environmental systems with hybrid Petri nets enables the construction of complex processes while keeping the models comprehensible for researchers working on the same project with significantly divergent education path. In this paper we propose the utilization of a special class of hybrid Petri nets, Generalized Hybrid Petri Nets (GHPN, to model and simulate environmental systems exposing processes interacting at different time-scales. GHPN integrate stochastic and deterministic semantics as well as other types of special basic events. Moreover, a case study is presented to illustrate the use of GHPN in constructing and simulating multi-timescale environmental scenarios.

  3. NOy production, ozone loss and changes in net radiative heating due to energetic particle precipitation in 2002-2010

    Sinnhuber, Miriam; Berger, Uwe; Funke, Bernd; Nieder, Holger; Reddmann, Thomas; Stiller, Gabriele; Versick, Stefan; von Clarmann, Thomas; Maik Wissing, Jan

    2018-01-01

    We analyze the impact of energetic particle precipitation on the stratospheric nitrogen budget, ozone abundances and net radiative heating using results from three global chemistry-climate models considering solar protons and geomagnetic forcing due to auroral or radiation belt electrons. Two of the models cover the atmosphere up to the lower thermosphere, the source region of auroral NO production. Geomagnetic forcing in these models is included by prescribed ionization rates. One model reaches up to about 80 km, and geomagnetic forcing is included by applying an upper boundary condition of auroral NO mixing ratios parameterized as a function of geomagnetic activity. Despite the differences in the implementation of the particle effect, the resulting modeled NOy in the upper mesosphere agrees well between all three models, demonstrating that geomagnetic forcing is represented in a consistent way either by prescribing ionization rates or by prescribing NOy at the model top.Compared with observations of stratospheric and mesospheric NOy from the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) instrument for the years 2002-2010, the model simulations reproduce the spatial pattern and temporal evolution well. However, after strong sudden stratospheric warmings, particle-induced NOy is underestimated by both high-top models, and after the solar proton event in October 2003, NOy is overestimated by all three models. Model results indicate that the large solar proton event in October 2003 contributed about 1-2 Gmol (109 mol) NOy per hemisphere to the stratospheric NOy budget, while downwelling of auroral NOx from the upper mesosphere and lower thermosphere contributes up to 4 Gmol NOy. Accumulation over time leads to a constant particle-induced background of about 0.5-1 Gmol per hemisphere during solar minimum, and up to 2 Gmol per hemisphere during solar maximum. Related negative anomalies of ozone are predicted by the models in nearly every polar

  4. Virtual reality application for simulating and minimizing worker radiation exposure

    Kang, Ki Doo; Hajek, Brian K.; Lee, Yon Sik; Shin, Yoo Jin

    2004-01-01

    To plan work and preclude unexpected radiation exposures in a nuclear power plant, a virtual nuclear plant is a good solution. For this, there are prerequisites such as displaying real time radiation exposure data onto an avatar and preventing speed reduction caused by multiple users on the net-based system. The work space is divided into several sections and radiation information is extracted section by section. Based on the simulation algorithm, real time processing is applied to the events and movements of the avatar. Because there are millions of parts in a nuclear power plant, it is almost impossible to model all of them. Several parts of virtual plant have been modeled using 3D internet virtual reality for the model development. Optimum one-click Active-X is applied for the system, which provides easy access to the virtual plant. Connection time on the net is 20-30 sec for initial loading and 3-4 sec for the 2nd and subsequent times

  5. Effect of gamma radiation on chlorophylls content, net photosynthesis and respiration of Chlorella pyrenoidosa

    Martin Moreno, C.; Fernandez Gonzalez, J.

    1983-01-01

    The effect of five doses of gamma radiation: 10, 100, 500, 1000 and 5000 Gy on chlorophylls content, net photosynthesis and respiration of Chlorella pyrenoidosa has been studied. A decrease in chlorophylls levels is produced after irradiation at 500, 1000 and 5000 Gy, being, at first b chlorophyll affected to a greater extent than a chlorophyll. Net photosynthesis and respiration decline throughout the time of the observation after irradiation, this depressing effect being much more remarkable for the first one. Met photosynthesis inhibition levels of about 30% are got only five hours post irradiation at a dose of 5000 Gy. Radio estimation by low doses, although obtained in some cases for tho 10 Gy dose, has not been statistically confirmed. (Author) 23 refs

  6. Independent Review of Simulation of Net Infiltration for Present-Day and Potential Future Climates

    Review Panel: Soroosh Sorooshian, Ph.D., Panel Chairperson, University of California, Irvine; Jan M. H. Hendrickx, Ph.D., New Mexico Institute of Mining and Technology; Binayak P. Mohanty, Ph.D., Texas A& M University; Scott W. Tyler, Ph.D., University of Nevada, Reno; Tian-Chyi Jim Yeh, Ph.D., University of Arizona -- ORISE Review Facilitators: Robert S. Turner, Ph.D., Technical Review Group Manager, Oak Ridge Institute for Science and Education; Brian R. Herndon, Project Manager, Oak Ridge Institute for Science and Education; Russ Manning, Technical Writer/Editor, Haselwood Enterprises, Inc.

    2008-08-30

    The DOE Office of Civilian Radioactive Waste Management (OCRWM) tasked Oak Ridge Institute for Science and Education (ORISE) with providing an independent expert review of the documented model and prediction results for net infiltration of water into the unsaturated zone at Yucca Mountain. The specific purpose of the model, as documented in the report MDL-NBS-HS-000023, Rev. 01, is “to provide a spatial representation, including epistemic and aleatory uncertainty, of the predicted mean annual net infiltration at the Yucca Mountain site ...” (p. 1-1) The expert review panel assembled by ORISE concluded that the model report does not provide a technically credible spatial representation of net infiltration at Yucca Mountain. Specifically, the ORISE Review Panel found that: • A critical lack of site-specific meteorological, surface, and subsurface information prevents verification of (i) the net infiltration estimates, (ii) the uncertainty estimates of parameters caused by their spatial variability, and (iii) the assumptions used by the modelers (ranges and distributions) for the characterization of parameters. The paucity of site-specific data used by the modeling team for model implementation and validation is a major deficiency in this effort. • The model does not incorporate at least one potentially important hydrologic process. Subsurface lateral flow is not accounted for by the model, and the assumption that the effect of subsurface lateral flow is negligible is not adequately justified. This issue is especially critical for the wetter climate periods. This omission may be one reason the model results appear to underestimate net infiltration beneath wash environments and therefore imprecisely represent the spatial variability of net infiltration. • While the model uses assumptions consistently, such as uniform soil depths and a constant vegetation rooting depth, such assumptions may not be appropriate for this net infiltration simulation because they

  7. Independent Review of Simulation of Net Infiltration for Present-Day and Potential Future Climates

    Review Panel: Soroosh Sorooshian, Jan M. H. Hendrickx; Binayak P. Mohanty, Scott W. Tyler; Tian-Chyi Jim Yeh; Robert S. Turner; Brian R. Herndon; Russ Manning

    2008-01-01

    The DOE Office of Civilian Radioactive Waste Management (OCRWM) tasked Oak Ridge Institute for Science and Education (ORISE) with providing an independent expert review of the documented model and prediction results for net infiltration of water into the unsaturated zone at Yucca Mountain. The specific purpose of the model, as documented in the report MDL-NBS-HS-000023, Rev. 01, is 'to provide a spatial representation, including epistemic and aleatory uncertainty, of the predicted mean annual net infiltration at the Yucca Mountain site' (p. 1-1). The expert review panel assembled by ORISE concluded that the model report does not provide a technically credible spatial representation of net infiltration at Yucca Mountain. Specifically, the ORISE Review Panel found that: A critical lack of site-specific meteorological, surface, and subsurface information prevents verification of (1) the net infiltration estimates, (2) the uncertainty estimates of parameters caused by their spatial variability, and (3) the assumptions used by the modelers (ranges and distributions) for the characterization of parameters. The paucity of site-specific data used by the modeling team for model implementation and validation is a major deficiency in this effort. The model does not incorporate at least one potentially important hydrologic process. Subsurface lateral flow is not accounted for by the model, and the assumption that the effect of subsurface lateral flow is negligible is not adequately justified. This issue is especially critical for the wetter climate periods. This omission may be one reason the model results appear to underestimate net infiltration beneath wash environments and therefore imprecisely represent the spatial variability of net infiltration. While the model uses assumptions consistently, such as uniform soil depths and a constant vegetation rooting depth, such assumptions may not be appropriate for this net infiltration simulation because they oversimplify a complex

  8. Online external beam radiation treatment simulator

    Hamza-Lup, Felix G.; Sopin, Ivan; Zeidan, Omar

    2008-01-01

    Radiation therapy is an effective and widely accepted form of treatment for many types of cancer that requires extensive computerized planning. Unfortunately, current treatment planning systems have limited or no visual aid that combines patient volumetric models extracted from patient-specific CT data with the treatment device geometry in a 3D interactive simulation. We illustrate the potential of 3D simulation in radiation therapy with a web-based interactive system that combines novel standards and technologies. We discuss related research efforts in this area and present in detail several components of the simulator. An objective assessment of the accuracy of the simulator and a usability study prove the potential of such a system for simulation and training. (orig.)

  9. Effects of UVB radiation on net community production in the upper global ocean

    Garcia-Corral, Lara S.

    2016-08-31

    Aim Erosion of the stratospheric ozone layer together with oligotrophication of the subtropical ocean is leading to enhanced exposure to ultraviolet B (UVB) radiation in ocean surface waters. The impact of increased exposure to UVB on planktonic primary producers and heterotrophs is uncertain. Here we test the null hypothesis that net community production (NCP) of plankton communities in surface waters of the tropical and subtropical ocean is not affected by ambient UVB radiation and extend this test to the global ocean, including the polar oceans and the Mediterranean Sea using previous results. Location We conducted experiments with 131 surface communities sampled during a circumnavigation cruise along the tropical and subtropical ocean and combined these results with 89 previous reports encompassing the Atlantic, Pacific, Arctic and Southern Oceans and the Mediterranean Sea. Methods The use of quartz (transparent to UVB radiation) and borosilicate glass materials (opaque to most UVB) for incubations allowed us to compare NCP between communities where UVB is excluded and those receiving natural UVB radiation. Results We found that NCP varies when exposed to natural UVB radiation compared to those where UVB was removed. NCP of autotrophic communities tended to decrease under natural UVB radiation, whereas the NCP of heterotrophic communities tended to increase. However, these variations showed the opposite trend under higher levels of UVB radiation. Main conclusions Our results suggest that earlier estimates of NCP for surface communities, which were hitherto derived using materials blocking UVB radiation were biased, with the direction and magnitude of this bias depending on the metabolic status of the communities and the underwater penetration of UVB radiation.

  10. Accuracy assessment of a net radiation and temperature index snowmelt model using ground observations of snow water equivalent in an alpine basin

    Molotch, N. P.; Painter, T. H.; Bales, R. C.; Dozier, J.

    2003-04-01

    In this study, an accumulated net radiation / accumulated degree-day index snowmelt model was coupled with remotely sensed snow covered area (SCA) data to simulate snow cover depletion and reconstruct maximum snow water equivalent (SWE) in the 19.1-km2 Tokopah Basin of the Sierra Nevada, California. Simple net radiation snowmelt models are attractive for operational snowmelt runoff forecasts as they are computationally inexpensive and have low input requirements relative to physically based energy balance models. The objective of this research was to assess the accuracy of a simple net radiation snowmelt model in a topographically heterogeneous alpine environment. Previous applications of net radiation / temperature index snowmelt models have not been evaluated in alpine terrain with intensive field observations of SWE. Solar radiation data from two meteorological stations were distributed using the topographic radiation model TOPORAD. Relative humidity and temperature data were distributed based on the lapse rate calculated between three meteorological stations within the basin. Fractional SCA data from the Landsat Enhanced Thematic Mapper (5 acquisitions) and the Airborne Visible and Infrared Imaging Spectrometer (AVIRIS) (2 acquisitions) were used to derive daily SCA using a linear regression between acquisition dates. Grain size data from AVIRIS (4 acquisitions) were used to infer snow surface albedo and interpolated linearly with time to derive daily albedo values. Modeled daily snowmelt rates for each 30-m pixel were scaled by the SCA and integrated over the snowmelt season to obtain estimates of maximum SWE accumulation. Snow surveys consisting of an average of 335 depth measurements and 53 density measurements during April, May and June, 1997 were interpolated using a regression tree / co-krig model, with independent variables of average incoming solar radiation, elevation, slope and maximum upwind slope. The basin was clustered into 7 elevation / average-solar-radiation

  11. Coherent Synchrotron Radiation: Theory and Simulations

    Novokhatski, Alexander

    2012-01-01

    The physics of coherent synchrotron radiation (CSR) emitted by ultra-relativistic electron bunches, known since the last century, has become increasingly important with the development of high peak current free electron lasers and shorter bunch lengths in storage rings. Coherent radiation can be described as a low frequency part of the familiar synchrotron radiation in bending magnets. As this part is independent of the electron energy, the fields of different electrons of a short bunch can be in phase and the total power of the radiation will be quadratic with the number of electrons. Naturally the frequency spectrum of the longitudinal electron distribution in a bunch is of the same importance as the overall electron bunch length. The interest in the utilization of high power radiation from the terahertz and far infrared region in the field of chemical, physical and biological processes has led synchrotron radiation facilities to pay more attention to the production of coherent radiation. Several laboratories have proposed the construction of a facility wholly dedicated to terahertz production using the coherent radiation in bending magnets initiated by the longitudinal instabilities in the ring. Existing synchrotron radiation facilities also consider such a possibility among their future plans. There is a beautiful introduction to CSR in the 'ICFA Beam Dynamics Newsletter' N 35 (Editor C. Biscari). In this paper we recall the basic properties of CSR from the theory and what new effects, we can get from the precise simulations of the coherent radiation using numerical solutions of Maxwell's equations. In particular, transverse variation of the particle energy loss in a bunch, discovered in these simulations, explains the slice emittance growth in bending magnets of the bunch compressors and transverse de-coherence in undulators. CSR may play same the role as the effect of quantum fluctuations of synchrotron radiation in damping rings. It can limit the minimum

  12. Dynamic response of the thermometric net radiometer

    J. D. Wilson; W. J. Massman; G. E. Swaters

    2009-01-01

    We computed the dynamic response of an idealized thermometric net radiometer, when driven by an oscillating net longwave radiation intended roughly to simulate rapid fluctuations of the radiative environment such as might be expected during field use of such devices. The study was motivated by curiosity as to whether non-linearity of the surface boundary conditions...

  13. Robust modelling and simulation integration of SIMIO with coloured petri nets

    De La Mota, Idalia Flores; Mujica Mota, Miguel; Angel Piera, Miquel

    2017-01-01

    This book presents for the first time a methodology that combines the power of a modelling formalism such as colored petri nets with the flexibility of a discrete event program such as SIMIO. Industrial practitioners have seen the growth of simulation as a methodology for tacking problems in which variability is the common denominator. Practically all industrial systems, from manufacturing to aviation are considered stochastic systems. Different modelling techniques have been developed as well as mathematical techniques for formalizing the cause-effect relationships in industrial and complex systems. The methodology in this book illustrates how complexity in modelling can be tackled by the use of coloured petri nets, while at the same time the variability present in systems is integrated in a robust fashion. The book can be used as a concise guide for developing robust models, which are able to efficiently simulate the cause-effect relationships present in complex industrial systems without losing the simulat...

  14. Ionizing radiations simulation on bipolar components

    Montagner, X.

    1999-01-01

    This thesis presents the ionizing radiation effects on bipolar components and more specially their behavior facing the total dose. The first part is devoted to the radiation environments with a special attention to the spatial environments and new emergent environments. The specificities of bipolar components are then presented and their behavior facing the interactions. The physical mechanisms bound to the dose rate are also discussed. The second part presents a physical analysis of degradations induced by the cumulated dosimetry on bipolar components and simulation with the ATLAS code. The third part exposes an electric empirical simulation induced by the cumulated dose in static conditions. (A.L.B.)

  15. Video studies of passage by Anopheles gambiae mosquitoes through holes in a simulated bed net: effects of hole size, hole orientation and net environment.

    Sutcliffe, James; Colborn, Kathryn L

    2015-05-13

    Holes in netting provide potential routes for mosquitoes to enter ITNs. Despite this, there is little information on how mosquitoes respond to holes in bed nets and how their responses are affected by hole size, shape and orientation or by ambient conditions around the net. Female Anopheles gambiae (G3) were recorded in a simulated bed net consisting of two sizes of untreated netting-covered behavioural arenas placed above and beside (to simulate the bed net roof and sides respectively) the experimenter who was a source of host cues from 'inside' the net. A round hole of 9 mm or 13 mm diameter was cut into the centre of the netting of each arena. Videos of unfed female mosquitoes in arenas were analysed for time spent flying, walking and standing still and for exit through the hole. The effects of the experimenter on temperature and relative humidity around the simulated net were also measured. Mosquitoes were significantly more active in overhead arenas than in arenas to the side. Hole passage was significantly more likely in smaller arenas than larger ones and for larger holes than smaller ones. In arenas to the side, hole passage rate through small holes was about 50% less likely than what could be explained by area alone. Passage rate through holes in overhead arenas was consistent with hole area. Temperature in arenas did not strongly reflect the experimenter's presence in the simulated net. Relative humidity and absolute humidity in overhead arenas, but not in arenas to the side, were immediately affected by experimenter presence. Higher levels of activity in overhead arenas than in arenas to the side were likely due to the rising heat and humidity plume from the experimenter. Lower than expected passage rates through smaller vertically oriented holes may have been be due to an edge effect that does not apply to horizontally oriented holes. Results suggest that current methods of assessing the importance of physical damage to ITNs may not accurately reflect

  16. Quantifying the Contributions of Environmental Parameters to Ceres Surface Net Radiation Error in China

    Pan, X.; Yang, Y.; Liu, Y.; Fan, X.; Shan, L.; Zhang, X.

    2018-04-01

    Error source analyses are critical for the satellite-retrieved surface net radiation (Rn) products. In this study, we evaluate the Rn error sources in the Clouds and the Earth's Radiant Energy System (CERES) project at 43 sites from July in 2007 to December in 2007 in China. The results show that cloud fraction (CF), land surface temperature (LST), atmospheric temperature (AT) and algorithm error dominate the Rn error, with error contributions of -20, 15, 10 and 10 W/m2 (net shortwave (NSW)/longwave (NLW) radiation), respectively. For NSW, the dominant error source is algorithm error (more than 10 W/m2), particularly in spring and summer with abundant cloud. For NLW, due to the high sensitivity of algorithm and large LST/CF error, LST and CF are the largest error sources, especially in northern China. The AT influences the NLW error large in southern China because of the large AT error in there. The total precipitable water has weak influence on Rn error even with the high sensitivity of algorithm. In order to improve Rn quality, CF and LST (AT) error in northern (southern) China should be decreased.

  17. Efficient Data-Structures and Algorithms for a Coloured Petri Nets Simulator

    Mortensen, Kjeld Høyer

    2001-01-01

    In this paper we describe how efficient data-structures and algorithms are used to dramatically improve the performance of a simulator for Coloured Petri Nets compared with earlier versions. We have improved the simulator with respect to three areas: Firstly we have improved the transition...... of other transitions. Secondly we have improved the data-structures which hold multi-sets for markings. A kind of weight-balanced trees, called BB-trees. are used instead of lists as in the original version of the simulator. Although this kind of trees are more difficult to maintain at run...... "recipe" which is specially generated and optimised for each individual transition. The improved simulator is implemented in both the Design/CPN and CPN tools software packages, and has been used in several industrial projects....

  18. Analysis of the radiation budget in regional climate simulations with COSMO-CLM for Africa

    Steffen Kothe

    2014-09-01

    Full Text Available This study analysed two regional climate simulations for Africa regarding the radiation budgets with particular focus on the contribution of potentially influential parameters on uncertainties in the radiation components. The ERA-Interim driven simulations have been performed with the COSMO-CLM (grid-spacings of 0.44 ° or 0.22 °. The simulated budgets were compared to the satellite-based Global Energy and Water Cycle Experiment Surface Radiation Budget and ERA-Interim data sets. The COSMO-CLM tended to underestimate the net solar radiation and the outgoing long-wave radiation, and showed a regionally varying over- or underestimation in all budget components. An increase in horizontal resolution from 0.44 ° to 0.22 ° slightly reduced the mean errors by up to 5 %. Especially over sea regions, uncertainties in cloud fraction were the main influencing parameter on errors in the simulated radiation fluxes. Compared to former simulations the introduction of a new bare soil albedo treatment reduced the influence of uncertainties in surface albedo significantly. Over the African continent errors in aerosol optical depth and skin temperature were regionally important sources for the discrepancies within the simulated radiation. In a sensitivity test it was shown that the use of aerosol optical depth values from the MACC reanalysis product improved the simulated surface radiation substantially.

  19. Online Simulation of Radiation Track Structure Project

    Plante, Ianik

    2015-01-01

    Space radiation comprises protons, helium and high charged and energy (HZE) particles. High-energy particles are a concern for human space flight, because they are no known options for shielding astronauts from them. When these ions interact with matter, they damage molecules and create radiolytic species. The pattern of energy deposition and positions of the radiolytic species, called radiation track structure, is highly dependent on the charge and energy of the ion. The radiolytic species damage biological molecules, which may lead to several long-term health effects such as cancer. Because of the importance of heavy ions, the radiation community is very interested in the interaction of HZE particles with DNA, notably with regards to the track structure. A desktop program named RITRACKS was developed to simulate radiation track structure. The goal of this project is to create a web interface to allow registered internal users to use RITRACKS remotely.

  20. G4Beamline Program for Radiation Simulations

    Beard, Kevin; Roberts, Thomas J.; Degtiarenko, Pavel

    2008-01-01

    G4beamline, a program that is an interface to the Geant4 toolkit that we have developed to simulate accelerator beamlines, is being extended with a graphical user interface to quickly and efficiently model experimental equipment and its shielding in experimental halls. The program is flexible, user friendly, and requires no programming by users, so that even complex systems can be simulated quickly. This improved user interface is of much wider application than just the shielding simulations that are the focus of this project. As an initial application, G4beamline is being extended to provide the simulations that are needed to determine the radiation sources for the proposed experiments at Jefferson Laboratory so that shielding issues can be evaluated. Since the program already has the capabilities needed to simulate the transport of all known particles, including scattering, attenuation, interactions, and decays, the extension involves implementing a user-friendly graphical user inter

  1. Radiation risk of tissue late effects, a net consequence of probabilities of various cellular responses

    Feinendegen, L.E.

    1991-01-01

    Late effects from the exposure to low doses of ionizing radiation are hardly or not at all observed in man mainly due to the low values of risk coefficients that preclude statistical analyses of data from populations that are exposed to doses less than 0.2 Gy. In order to arrive at an assessment of potential risk from radiation exposure in the low dose range, the microdosimetry approach is essential. In the low dose range, ionizing radiation generates particle tracks, mainly electrons, which are distributed rather heterogeneously within the exposed tissue. Taking the individual cell as the elemental unit of life, observations and calculations of cellular responses to being hit by energy depositions events from low LET type are analysed. It emerges that besides the probability of a hit cell to sustain a detrimental effect with the consequense of malignant transformation there are probabilities of various adaptive responses that equipp the hit cell with a benefit. On the one hand, an improvement of cellular radical detoxification was observed in mouse bone marrow cells; another adaptive response pertaining to improved DNA repair, was reported for human lymphocytes. The improved radical detoxification in mouse bone marrow cells lasts for a period of 5-10 hours and improved DNA repair in human lymphocytes was seen for some 60 hours following acute irradiation. It is speculated that improved radical detoxification and improved DNA repair may reduce the probability of spontaneous carcinogenesis. Thus it is proposed to weigh the probability of detriment for a hit cell within a multicellular system against the probability of benefit through adaptive responses in other hit cells in the same system per radiation exposure. In doing this, the net effect of low doses of low LET radiation in tissue with individual cells being hit by energy deposition events could be zero or even beneficial. (orig./MG)

  2. Estimation of Net Radiation in Three Different Plant Functional Types in Korea

    Kwon, H.J.

    2009-01-01

    Net Radiation (R N ) is the major driving force for biophysical and biogeochemical processes in the terrestrial ecosystems, which is one of the most critical variables in both measurement and modeling. Despite its importance, there are only 10 weather stations conducting R N measurements among the 544 stations operated by Korea Meteorological Administration (KMA; KMA, 2008). The measurement of incoming shortwave radiation (R S ↓) is, however, conducted at 22 stations while that of sunshine duration is conducted at all the manned stations. In this context, the recent research for estimating R N using R S ↓ in Korean peninsula by Kwon (2009) is of great worth. The author used a linear regression and the radiation balance methods. We generally agree with the author that, in terms of simplicity and practicality, both methods show reliable applicability for estimating R N . We noted, however, that the author’s experimental method and analysis need some clarification and improvement, that are addressed in the following perspectives: (1) the use of daily integrated data for regression, (2) the use of measured albedo, (3) the use of linear coefficients for whole year data, (4) methodological improvement, (5) the use of sunshine duration, and (6) the error assessment. (author)

  3. Ambient UV-B radiation reduces PSII performance and net photosynthesis in high Arctic Salix arctica

    Albert, Kristian Rost; Mikkelsen, Teis Nørgaard; Ro-Poulsen, Helge

    2011-01-01

    Ambient ultraviolet-B (UV-B) radiation potentially impacts the photosynthetic performance of high Arctic plants. We conducted an UV-B exclusion experiment in a dwarf shrub heath in NE Greenland (74°N), with open control, filter control, UV-B filtering and UV-AB filtering, all in combination......, nitrogen and UV-B absorbing compounds. Compared to a 60% reduced UV-B irradiance, the ambient solar UV-B reduced net photosynthesis in Salix arctica leaves fixed in the 45° position which exposed leaves to maximum natural irradiance. Also a reduced Calvin Cycle capacity was found, i.e. the maximum rate...... across position in the vegetation. These findings add to the evidence that the ambient solar UV-B currently is a significant stress factor for plants in high Arctic Greenland....

  4. Simulation of radiation-induced defects

    Peltola, Timo

    2015-09-14

    Mainly due to their outstanding performance the position sensitive silicon detectors are widely used in the tracking systems of High Energy Physics experiments such as the ALICE, ATLAS, CMS and LHCb at LHC, the world's largest particle physics accelerator at CERN, Geneva. The foreseen upgrade of the LHC to its high luminosity (HL) phase (HL-LHC scheduled for 2023), will enable the use of maximal physics potential of the facility. After 10 years of operation the expected fluence will expose the tracking systems at HL-LHC to a radiation environment that is beyond the capacity of the present system design. Thus, for the required upgrade of the all-silicon central trackers extensive measurements and simulation studies for silicon sensors of different designs and materials with sufficient radiation tolerance have been initiated within the RD50 Collaboration. Supplementing measurements, simulations are in vital role for e.g. device structure optimization or predicting the electric fields and trapping in the silicon...

  5. Integrated logistic support studies using behavioral Monte Carlo simulation, supported by Generalized Stochastic Petri Nets

    Garnier, Robert; Chevalier, Marcel

    2000-01-01

    Studying large and complex industrial sites, requires more and more accuracy in modeling. In particular, when considering Spares, Maintenance and Repair / Replacement processes, determining optimal Integrated Logistic Support policies requires a high level modeling formalism, in order to make the model as close as possible to the real considered processes. Generally, numerical methods are used to process this kind of study. In this paper, we propose an alternate way to process optimal Integrated Logistic Support policy determination when dealing with large, complex and distributed multi-policies industrial sites. This method is based on the use of behavioral Monte Carlo simulation, supported by Generalized Stochastic Petri Nets. (author)

  6. CPN/Tools: A Post-WIMP Interface for Editing and Simulating Coloured Petri Nets

    Andersen, Peter; Beaudouin-Lafon, Michel; Mackay, Wendy E.

    2001-01-01

    traditional ideas about user interfaces, getting rid of pull-down menus, scrollbars, and even selection, while providing the same or greater functionality. It also uses the new and much faster CPN simulator and features incremental syntax checking of the nets. CPN/Tools requires an OpenGL graphics accelerator......CPN/Tools is a major redesign of the popular Design/CPN tool from the University of Aarhus CPN group. The new interface is based on advanced, post-WIMP interaction techniques, including bi-manual interaction, toolglasses and marking menus and a new metaphor for managing the workspace. It challenges...

  7. Simulation of distribution nets for natural gas, in stationary state considering the compressible effects

    Valbuena C, Javier

    1997-01-01

    The general method is presented to calculate the losses of pressure in a RTD starting from the geometry of the net (diameter and longitude), of the real behavior of the gas, of the ruggedness of the pipe and of the flow, considering the compressibility of the fluid so much as the influence of the compressible effects. The simulation method is derived of the principles of conservation of mass and energy for a gas that follows a reversible poly tropic process of stable state and stable flow - stationary regime

  8. Net Surface Shortwave Radiation from GOES Imagery—Product Evaluation Using Ground-Based Measurements from SURFRAD

    Anand K. Inamdar

    2015-08-01

    Full Text Available The Earth’s surface net radiation controls the energy and water exchanges between the Earth’s surface and the atmosphere, and can be derived from satellite observations. The ability to monitor the net surface radiation over large areas at high spatial and temporal resolution is essential for many applications, such as weather forecasting, short-term climate prediction or water resources management. The objective of this paper is to derive the net surface radiation in the shortwave domain at high temporal (half-hourly and spatial resolution (~1 km using visible imagery from Geostationary Operational Environmental Satellite (GOES. The retrieval algorithm represents an adaptation to GOES data of a standard algorithm initially developed for the NASA-operated Clouds and Earth’s Radiant Energy System (CERES scanner. The methodology relies on: (1 the estimation of top of atmosphere shortwave radiation from GOES spectral measurements; and (2 the calculation of net surface shortwave (SW radiation accounting for atmospheric effects. Comparison of GOES-retrieved net surface shortwave radiation with ground-measurements at the National Oceanic and Atmospheric Administration’s (NOAA Surface Radiation (SURFRAD stations yields very good agreement with average bias lower than 5 W·m−2 and root mean square difference around 70 W·m−2. The algorithm performance is usually higher over areas characterized by low spatial variability in term of land cover type and surface biophysical properties. The technique does not involve retrieval and assessment of cloud properties and can be easily adapted to other meteorological satellites around the globe.

  9. NOy production, ozone loss and changes in net radiative heating due to energetic particle precipitation in 2002–2010

    M. Sinnhuber

    2018-01-01

    Full Text Available We analyze the impact of energetic particle precipitation on the stratospheric nitrogen budget, ozone abundances and net radiative heating using results from three global chemistry-climate models considering solar protons and geomagnetic forcing due to auroral or radiation belt electrons. Two of the models cover the atmosphere up to the lower thermosphere, the source region of auroral NO production. Geomagnetic forcing in these models is included by prescribed ionization rates. One model reaches up to about 80 km, and geomagnetic forcing is included by applying an upper boundary condition of auroral NO mixing ratios parameterized as a function of geomagnetic activity. Despite the differences in the implementation of the particle effect, the resulting modeled NOy in the upper mesosphere agrees well between all three models, demonstrating that geomagnetic forcing is represented in a consistent way either by prescribing ionization rates or by prescribing NOy at the model top.Compared with observations of stratospheric and mesospheric NOy from the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS instrument for the years 2002–2010, the model simulations reproduce the spatial pattern and temporal evolution well. However, after strong sudden stratospheric warmings, particle-induced NOy is underestimated by both high-top models, and after the solar proton event in October 2003, NOy is overestimated by all three models. Model results indicate that the large solar proton event in October 2003 contributed about 1–2 Gmol (109 mol NOy per hemisphere to the stratospheric NOy budget, while downwelling of auroral NOx from the upper mesosphere and lower thermosphere contributes up to 4 Gmol NOy. Accumulation over time leads to a constant particle-induced background of about 0.5–1 Gmol per hemisphere during solar minimum, and up to 2 Gmol per hemisphere during solar maximum. Related negative anomalies of ozone are predicted by

  10. Simulation of photoconductive antennas for terahertz radiation

    Carlos Criollo

    2015-01-01

    Full Text Available Simulation of terahertz (THz emission based on PC antennas imposes a challenge to couple the semiconductor carrier phenomena, optical transport and the THz energy transport. In this paper a Multi-physics simulation for coupling these phenomena using COMSOL Multi-physics 4.3b is introduced. The main parameters of THz photoconductive (PC antenna as THz emitter have been reviewed and discussed. The results indicate the role of each parameter in the resulting photocurrent waveform and THz frequency: The radiated THz photocurrent waveform is determined by the photoconductive gap (the separation between the metallic electrodes, the incident laser illumination and the DC excitation voltage; while the THz frequency depends on the dipole length. The optimization of these parameters could enhance the emission. The simulations extend the advance of compact and cost-effective THz emitters.

  11. A virtual radiation therapy workflow training simulation

    Bridge, P.; Crowe, S.B.; Gibson, G.; Ellemor, N.J.; Hargrave, C.; Carmichael, M.

    2016-01-01

    Aim: Simulation forms an increasingly vital component of clinical skills development in a wide range of professional disciplines. Simulation of clinical techniques and equipment is designed to better prepare students for placement by providing an opportunity to learn technical skills in a “safe” academic environment. In radiotherapy training over the last decade or so this has predominantly comprised treatment planning software and small ancillary equipment such as mould room apparatus. Recent virtual reality developments have dramatically changed this approach. Innovative new simulation applications and file processing and interrogation software have helped to fill in the gaps to provide a streamlined virtual workflow solution. This paper outlines the innovations that have enabled this, along with an evaluation of the impact on students and educators. Method: Virtual reality software and workflow applications have been developed to enable the following steps of radiation therapy to be simulated in an academic environment: CT scanning using a 3D virtual CT scanner simulation; batch CT duplication; treatment planning; 3D plan evaluation using a virtual linear accelerator; quantitative plan assessment, patient setup with lasers; and image guided radiotherapy software. Results: Evaluation of the impact of the virtual reality workflow system highlighted substantial time saving for academic staff as well as positive feedback from students relating to preparation for clinical placements. Students valued practice in the “safe” environment and the opportunity to understand the clinical workflow ahead of clinical department experience. Conclusion: Simulation of most of the radiation therapy workflow and tasks is feasible using a raft of virtual reality simulation applications and supporting software. Benefits of this approach include time-saving, embedding of a case-study based approach, increased student confidence, and optimal use of the clinical environment

  12. Rare event simulation in radiation transport

    Kollman, C.

    1993-10-01

    This dissertation studies methods for estimating extremely small probabilities by Monte Carlo simulation. Problems in radiation transport typically involve estimating very rare events or the expected value of a random variable which is with overwhelming probability equal to zero. These problems often have high dimensional state spaces and irregular geometries so that analytic solutions are not possible. Monte Carlo simulation must be used to estimate the radiation dosage being transported to a particular location. If the area is well shielded the probability of any one particular particle getting through is very small. Because of the large number of particles involved, even a tiny fraction penetrating the shield may represent an unacceptable level of radiation. It therefore becomes critical to be able to accurately estimate this extremely small probability. Importance sampling is a well known technique for improving the efficiency of rare event calculations. Here, a new set of probabilities is used in the simulation runs. The results are multiple by the likelihood ratio between the true and simulated probabilities so as to keep the estimator unbiased. The variance of the resulting estimator is very sensitive to which new set of transition probabilities are chosen. It is shown that a zero variance estimator does exist, but that its computation requires exact knowledge of the solution. A simple random walk with an associated killing model for the scatter of neutrons is introduced. Large deviation results for optimal importance sampling in random walks are extended to the case where killing is present. An adaptive ''learning'' algorithm for implementing importance sampling is given for more general Markov chain models of neutron scatter. For finite state spaces this algorithm is shown to give with probability one, a sequence of estimates converging exponentially fast to the true solution

  13. Analytical treatment of the relationships between soil heat flux/net radiation ratio and vegetation indices

    Kustas, W.P.; Daughtry, C.S.T.; Oevelen, P.J. van

    1993-01-01

    Relationships between leaf area index (LAI) and midday soil heat flux/net radiation ratio (G/R n ) and two more commonly used vegetation indices (VIs) were used to analytically derive formulas describing the relationship between G/R n and VI. Use of VI for estimating G/R n may be useful in operational remote sensing models that evaluate the spatial variation in the surface energy balance over large areas. While previous experimental data have shown that linear equations can adequately describe the relationship between G/Rn and VI, this analytical treatment indicated that nonlinear relationships are more appropriate. Data over bare soil and soybeans under a range of canopy cover conditions from a humid climate and data collected over bare soil, alfalfa, and cotton fields in an arid climate were used to evaluate model formulations derived for LAI and G/R n , LAI and VI, and VI and G/R n . In general, equations describing LAI-G/R n and LAI-VI relationships agreed with the data and supported the analytical result of a nonlinear relationship between VI and G/R n . With the simple ratio (NIR/Red) as the VI, the nonlinear relationship with G/R n was confirmed qualitatively. But with the normalized difference vegetation index (NDVI), a nonlinear relationship did not appear to fit the data. (author)

  14. Measurements and simulation of forest leaf area index and net primary productivity in Northern China.

    Wang, P; Sun, R; Hu, J; Zhu, Q; Zhou, Y; Li, L; Chen, J M

    2007-11-01

    Large scale process-based modeling is a useful approach to estimate distributions of global net primary productivity (NPP). In this paper, in order to validate an existing NPP model with observed data at site level, field experiments were conducted at three sites in northern China. One site is located in Qilian Mountain in Gansu Province, and the other two sites are in Changbaishan Natural Reserve and Dunhua County in Jilin Province. Detailed field experiments are discussed and field data are used to validate the simulated NPP. Remotely sensed images including Landsat Enhanced Thematic Mapper plus (ETM+, 30 m spatial resolution in visible and near infrared bands) and Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER, 15m spatial resolution in visible and near infrared bands) are used to derive maps of land cover, leaf area index, and biomass. Based on these maps, field measured data, soil texture and daily meteorological data, NPP of these sites are simulated for year 2001 with the boreal ecosystem productivity simulator (BEPS). The NPP in these sites ranges from 80 to 800 gCm(-2)a(-1). The observed NPP agrees well with the modeled NPP. This study suggests that BEPS can be used to estimate NPP in northern China if remotely sensed images of high spatial resolution are available.

  15. Rare Event Simulation in Radiation Transport

    Kollman, Craig

    This dissertation studies methods for estimating extremely small probabilities by Monte Carlo simulation. Problems in radiation transport typically involve estimating very rare events or the expected value of a random variable which is with overwhelming probability equal to zero. These problems often have high dimensional state spaces and irregular geometries so that analytic solutions are not possible. Monte Carlo simulation must be used to estimate the radiation dosage being transported to a particular location. If the area is well shielded the probability of any one particular particle getting through is very small. Because of the large number of particles involved, even a tiny fraction penetrating the shield may represent an unacceptable level of radiation. It therefore becomes critical to be able to accurately estimate this extremely small probability. Importance sampling is a well known technique for improving the efficiency of rare event calculations. Here, a new set of probabilities is used in the simulation runs. The results are multiplied by the likelihood ratio between the true and simulated probabilities so as to keep our estimator unbiased. The variance of the resulting estimator is very sensitive to which new set of transition probabilities are chosen. It is shown that a zero variance estimator does exist, but that its computation requires exact knowledge of the solution. A simple random walk with an associated killing model for the scatter of neutrons is introduced. Large deviation results for optimal importance sampling in random walks are extended to the case where killing is present. An adaptive "learning" algorithm for implementing importance sampling is given for more general Markov chain models of neutron scatter. For finite state spaces this algorithm is shown to give, with probability one, a sequence of estimates converging exponentially fast to the true solution. In the final chapter, an attempt to generalize this algorithm to a continuous

  16. Regional scale net radiation estimation by means of Landsat and TERRA/AQUA imagery and GIS modeling

    Cristóbal, J.; Ninyerola, M.; Pons, X.; Llorens, P.; Poyatos, R.

    2009-04-01

    Net radiation (Rn) is one of the most important variables for the estimation of surface energy budget and is used for various applications including agricultural meteorology, climate monitoring and weather prediction. Moreover, net radiation is an essential input variable for potential as well as actual evapotranspiration modeling. Nowadays, radiometric measurements provided by Remote Sensing and GIS analysis are the technologies used to compute net radiation at regional scales in a feasible way. In this study we present a regional scale estimation of the daily Rn on clear days, (Catalonia, NE of the Iberian Peninsula), using a set of 22 Landsat images (17 Landsat-5 TM and 5 Landsat-7 ETM+) and 171 TERRA/AQUA images MODIS from 2000 to 2007 period. TERRA/AQUA MODIS images have been downloaded by means of the EOS Gateway. We have selected three different types of products which contain the remote sensing data we have used to model daily Rn: daily LST product, daily calibrated reflectances product and daily atmospheric water vapour product. Landsat-5 TM images have been corrected by means of conventional techniques based on first order polynomials taking into account the effect of land surface relief using a Digital Elevation Model, obtaining an RMS less than 30 m. Radiometric correction of Landsat non-thermal bands has been done following the methodology proposed by Pons and Solé (1994), which allows to reduce the number of undesired artifacts that are due to the effects of the atmosphere or to the differential illumination which is, in turn, due to the time of the day, the location in the Earth and the relief (zones being more illuminated than others, shadows, etc). Atmospheric correction of Landsat thermal band has been carried out by means of a single-channel algorithm improvement developed by Cristóbal et al. (2009) and the land surface emissivity computed by means of the methodology proposed by Sobrino and Raissouni (2000). Rn has been estimated through the

  17. ePNK Applications and Annotations: A Simulator for YAWL Nets

    Kindler, Ekkart

    2018-01-01

    The ePNK is an Eclipse based platform and framework for developing and integrating Petri net tools and applications. New types of Petri nets can be realized and plugged into the ePNK without any programming by simply providing a model of the concepts of the new Petri net type. Moreover, the ePNK ...

  18. A simulator for high-level Petri nets: An ePNK application

    Kindler, Ekkart; Laganeckas, Mindaugas

    2013-01-01

    The ePNK is a platform for Petri net tools based on the PNML transfer format. One of its important features is its extensibility, which allows developers to plug in new Petri net types and new functions and applications for different kinds of Petri nets. The basic version of the ePNK provides...

  19. Surface radiation fluxes in transient climate simulations

    Garratt, J. R.; O'Brien, D. M.; Dix, M. R.; Murphy, J. M.; Stephens, G. L.; Wild, M.

    1999-01-01

    Transient CO 2 experiments from five coupled climate models, in which the CO 2 concentration increases at rates of 0.6-1.1% per annum for periods of 75-200 years, are used to document the responses of surface radiation fluxes, and associated atmospheric properties, to the CO 2 increase. In all five models, the responses of global surface temperature and column water vapour are non-linear and fairly tightly constrained. Thus, global warming lies between 1.9 and 2.7 K at doubled, and between 3.1 and 4.1 K at tripled, CO 2, whilst column water vapour increases by between 3.5 and 4.5 mm at doubled, and between 7 and 8 mm at tripled, CO 2. Global cloud fraction tends to decrease by 1-2% out to tripled CO 2, mainly the result of decreases in low cloud. Global increases in column water, and differences in these increases between models, are mainly determined by the warming of the tropical oceans relative to the middle and high latitudes; these links are emphasised in the zonal profiles of warming and column water vapour increase, with strong water vapour maxima in the tropics. In all models the all-sky shortwave flux to the surface S↓ (global, annual average) changes by less than 5 W m -2 out to tripled CO 2, in some cases being essentially invariant in time. In contrast, the longwave flux to the surface L↓ increases significantly, by 25 W m -2 typically at tripled CO 2. The variations of S↓ and L↓ (clear-sky and all-sky fluxes) with increase in CO 2 concentration are generally non-linear, reflecting the effects of ocean thermal inertia, but as functions of global warming are close to linear in all five models. This is best illustrated for the clear-sky downwelling fluxes, and the net radiation. Regionally, as illustrated in zonal profiles and global distributions, greatest changes in both S↓ and L↓ are the result primarily of local maxima in warming and column water vapour increases.

  20. Evaluation of a combined modelling-remote sensing method for estimating net radiation in a wetland: a case study in the Nebraska Sand Hills, USA

    Goodin, D.G.

    1995-01-01

    Close-range measurement combined with modelling of incoming radiation is used to evaluate the prospect of remotely-measuring net radiation of a wetland environment located in the Sand Hills of Nebraska. Results indicate that net radiation can be measured with an accuracy comparable to that of conventional instruments. Sources of error are identified and discussed. Possible application of the methodology to satellite remote sensing is considered. (author)

  1. Radiation Modeling with Direct Simulation Monte Carlo

    Carlson, Ann B.; Hassan, H. A.

    1991-01-01

    Improvements in the modeling of radiation in low density shock waves with direct simulation Monte Carlo (DSMC) are the subject of this study. A new scheme to determine the relaxation collision numbers for excitation of electronic states is proposed. This scheme attempts to move the DSMC programs toward a more detailed modeling of the physics and more reliance on available rate data. The new method is compared with the current modeling technique and both techniques are compared with available experimental data. The differences in the results are evaluated. The test case is based on experimental measurements from the AVCO-Everett Research Laboratory electric arc-driven shock tube of a normal shock wave in air at 10 km/s and .1 Torr. The new method agrees with the available data as well as the results from the earlier scheme and is more easily extrapolated to di erent ow conditions.

  2. Simulation of radiation in laser produced plasmas

    Colombant, D. G.; Klapisch, M.; Deniz, A. V.; Weaver, J.; Schmitt, A.

    1999-11-01

    The radiation hydrodynamics code FAST1D(J.H.Gardner,A.J.Schmitt,J.P.Dahlburg,C.J.Pawley,S.E.Bodner,S.P.Obenschain,V.Serlin and Y.Aglitskiy,Phys. Plasmas,5,1935(1998)) was used directly (i.e. without postprocessor) to simulate radiation emitted from flat targets irradiated by the Nike laser, from 10^12 W/cm^2 to 10^13W/cm^2. We use enough photon groups to resolve spectral lines. Opacities are obtained from the STA code(A.Bar-Shalom,J.Oreg,M.Klapisch and T.Lehecka,Phys.Rev.E,59,3512(1999)), and non LTE effects are described with the Busquet model(M.Busquet,Phys.Fluids B,5,4191(1993)). Results are compared to transmission grating spectra in the range 100-600eV, and to time-resolved calibrated filtered diodes (spectral windows around 100, 180, 280 and 450 eV).

  3. Simulation of net infiltration and potential recharge using a distributed-parameter watershed model of the Death Valley region, Nevada and California

    Hevesi, Joseph A.; Flint, Alan L.; Flint, Lorraine E.

    2003-01-01

    (as either rain or snow), snow accumulation, sublimation, snowmelt, infiltration into the root zone, evapotranspiration, drainage, water content change throughout the root-zone profile (represented as a 6-layered system), runoff (defined as excess rainfall and snowmelt) and surface water run-on (defined as runoff that is routed downstream), and net infiltration (simulated as drainage from the bottom root-zone layer). Potential evapotranspiration is simulated using an hourly solar radiation model to simulate daily net radiation, and daily evapotranspiration is simulated as an empirical function of root zone water content and potential evapotranspiration. The model uses daily climate records of precipitation and air temperature from a regionally distributed network of 132 climate stations and a spatially distributed representation of drainage basin characteristics defined by topography, geology, soils, and vegetation to simulate daily net infiltration at all locations, including stream channels with intermittent streamflow in response to runoff from rain and snowmelt. The temporal distribution of daily, monthly, and annual net infiltration can be used to evaluate the potential effect of future climatic conditions on potential recharge. The INFILv3 model inputs representing drainage basin characteristics were developed using a geographic information system (GIS) to define a set of spatially distributed input parameters uniquely assigned to each grid cell of the INFILv3 model grid. The model grid, which was defined by a digital elevation model (DEM) of the Death Valley region, consists of 1,252,418 model grid cells with a uniform grid cell dimension of 278.5 meters in the north-south and east-west directions. The elevation values from the DEM were used with monthly regression models developed from the daily climate data to estimate the spatial distribution of daily precipitation and air temperature. The elevation values were also used to simulate atmosp

  4. The positive net radiative greenhouse gas forcing of increasing methane emissions from a thawing boreal forest-wetland landscape.

    Helbig, Manuel; Chasmer, Laura E; Kljun, NatasCha; Quinton, William L; Treat, Claire C; Sonnentag, Oliver

    2017-06-01

    At the southern margin of permafrost in North America, climate change causes widespread permafrost thaw. In boreal lowlands, thawing forested permafrost peat plateaus ('forest') lead to expansion of permafrost-free wetlands ('wetland'). Expanding wetland area with saturated and warmer organic soils is expected to increase landscape methane (CH 4 ) emissions. Here, we quantify the thaw-induced increase in CH 4 emissions for a boreal forest-wetland landscape in the southern Taiga Plains, Canada, and evaluate its impact on net radiative forcing relative to potential long-term net carbon dioxide (CO 2 ) exchange. Using nested wetland and landscape eddy covariance net CH 4 flux measurements in combination with flux footprint modeling, we find that landscape CH 4 emissions increase with increasing wetland-to-forest ratio. Landscape CH 4 emissions are most sensitive to this ratio during peak emission periods, when wetland soils are up to 10 °C warmer than forest soils. The cumulative growing season (May-October) wetland CH 4 emission of ~13 g CH 4  m -2 is the dominating contribution to the landscape CH 4 emission of ~7 g CH 4  m -2 . In contrast, forest contributions to landscape CH 4 emissions appear to be negligible. The rapid wetland expansion of 0.26 ± 0.05% yr -1 in this region causes an estimated growing season increase of 0.034 ± 0.007 g CH 4  m -2  yr -1 in landscape CH 4 emissions. A long-term net CO 2 uptake of >200 g CO 2  m -2  yr -1 is required to offset the positive radiative forcing of increasing CH 4 emissions until the end of the 21st century as indicated by an atmospheric CH 4 and CO 2 concentration model. However, long-term apparent carbon accumulation rates in similar boreal forest-wetland landscapes and eddy covariance landscape net CO 2 flux measurements suggest a long-term net CO 2 uptake between 49 and 157 g CO 2  m -2  yr -1 . Thus, thaw-induced CH 4 emission increases likely exert a positive net radiative greenhouse gas

  5. Modelling and Simulating Complex Systems in Biology: introducing NetBioDyn : A Pedagogical and Intuitive Agent-Based Software

    Ballet, Pascal; Rivière, Jérémy; Pothet, Alain; Théron, Michaël; Pichavant, Karine; Abautret, Frank; Fronville, Alexandra; Rodin, Vincent

    2017-01-01

    International audience; Modelling and teaching complex biological systems is a difficult process. Multi-Agent Based Simulations (MABS) have proved to be an appropriate approach both in research and education when dealing with such systems including emergent, self-organizing phenomena. This chapter presents NetBioDyn, an original software aimed at biologists (students, teachers, researchers) to easily build and simulate complex biological mechanisms observed in multicellular and molecular syst...

  6. Evaluation of three semi-empirical approaches to estimate the net radiation over a drip-irrigated olive orchard

    Rafael López-Olivari

    2015-09-01

    Full Text Available The use of actual evapotranspiration (ETα models requires an appropriate parameterization of the available energy, where the net radiation (Rn is the most important component. Thus, a study was carried out to calibrate and evaluate three semi-empirical approaches to estimate net radiation (Rn over a drip-irrigated olive (Olea europaea L. 'Arbequina' orchard during 2009/2010 and 2010/2011 seasons. The orchard was planted in 2005 at high density in the Pencahue Valley, Maule Region, Chile. The evaluated models were calculated using the balance between long and short wave radiation. To achieve this objective it was assumed that Ts = Tα for Model 1, Ts = Tv for Model 2 and Ts = Tr for Model 3 (Ts is surface temperature; Tα is air temperature; and Tv is temperature inside of the tree canopy; Tr is radiometric temperature. For the three models, the Brutsaert's empirical coefficient (Φ was calibrated using incoming long wave radiation equation with the database of 2009/2010 season. Thus, the calibration indicated that Φ was equal to 1.75. Using the database from 2010/2011 season, the validation indicated that the three models were able to predict the Rn at a 30-min interval with errors lower than 6%, root mean square error (RMSE between 26 and 39 W m-2 and mean absolute error (MAE between 20 and 31 W m-2. On daily time intervals, validation indicated that models presented errors, RMSE and MAE between 2% and 3%, 1.22-1.54 and 1.04-1.35 MJ m-2 d-1, respectively. The three R„-Models would be evaluated and used in others Mediterranean conditions according to the availability of data to estimate net radiation over a drip-irrigated olive orchard planted at high density.

  7. Phased mission modelling of systems with maintenance-free operating periods using simulated Petri nets

    Chew, S.P.; Dunnett, S.J. [Department of Aeronautical and Automotive Engineering, Loughborough University, Loughborough, Leics (United Kingdom); Andrews, J.D. [Department of Aeronautical and Automotive Engineering, Loughborough University, Loughborough, Leics (United Kingdom)], E-mail: j.d.andrews@lboro.ac.uk

    2008-07-15

    A common scenario in engineering is that of a system which operates throughout several sequential and distinct periods of time, during which the modes and consequences of failure differ from one another. This type of operation is known as a phased mission, and for the mission to be a success the system must successfully operate throughout all of the phases. Examples include a rocket launch and an aeroplane flight. Component or sub-system failures may occur at any time during the mission, yet not affect the system performance until the phase in which their condition is critical. This may mean that the transition from one phase to the next is a critical event that leads to phase and mission failure, with the root cause being a component failure in a previous phase. A series of phased missions with no maintenance may be considered as a maintenance-free operating period (MFOP). This paper describes the use of a Petri net (PN) to model the reliability of the MFOP and phased missions scenario. The model uses Monte-Carlo simulation to obtain its results, and due to the modelling power of PNs, can consider complexities such as component failure rate interdependencies and mission abandonment. The model operates three different types of PN which interact to provide the overall system reliability modelling. The model is demonstrated and validated by considering two simple examples that can be solved analytically.

  8. Phased mission modelling of systems with maintenance-free operating periods using simulated Petri nets

    Chew, S.P.; Dunnett, S.J.; Andrews, J.D.

    2008-01-01

    A common scenario in engineering is that of a system which operates throughout several sequential and distinct periods of time, during which the modes and consequences of failure differ from one another. This type of operation is known as a phased mission, and for the mission to be a success the system must successfully operate throughout all of the phases. Examples include a rocket launch and an aeroplane flight. Component or sub-system failures may occur at any time during the mission, yet not affect the system performance until the phase in which their condition is critical. This may mean that the transition from one phase to the next is a critical event that leads to phase and mission failure, with the root cause being a component failure in a previous phase. A series of phased missions with no maintenance may be considered as a maintenance-free operating period (MFOP). This paper describes the use of a Petri net (PN) to model the reliability of the MFOP and phased missions scenario. The model uses Monte-Carlo simulation to obtain its results, and due to the modelling power of PNs, can consider complexities such as component failure rate interdependencies and mission abandonment. The model operates three different types of PN which interact to provide the overall system reliability modelling. The model is demonstrated and validated by considering two simple examples that can be solved analytically

  9. RadNet Map Interface for Near-Real-Time Radiation Monitoring Data

    U.S. Environmental Protection Agency — RadNet is a national network of monitoring stations that regularly collect air, precipitation, drinking water, and milk samples for analysis of radioactivity. The...

  10. Long-term changes in net radiation and its components above a pine forest and a grass surface in Germany

    Kessler, A.; Jaeger, L.

    1999-01-01

    Long-term measurements (1974–1993 and 1996, respectively) of the net radiation (Q), global radiation (G), reflected global radiation (R), long-wave atmospheric radiation (A) and thermal radiation (E) of a pine forest in Southern Germany (index p) and of a grass surface in Northern Germany (index g) are compared. The influence of changes in surface properties is discussed. There are, in the case of the pine stand, forest growth and forest management and in the case of the grass surface, the shifting of the site from a climatic garden to a horizontal roof. Both series of radiant fluxes are analyzed with respect to the influences of the weather (cloudiness, heat advection). To eliminate the different influence of the solar radiation of the two sites, it is necessary to normalize by means of the global radiation G, yielding the radiation efficiency Q/G, the albedo R/G=α and the normalized long-wave net radiation (A+E)/G. Furthermore, the long-term mean values and the long-term trend of yearly mean values are discussed and, moreover, a comparison is made of individual monthly values. Q p is twice as large as Q g . The reason for this is the higher values of G and A above the pine forest and half values of α p compared to α g . E p is only a little greater than E g . The time series of the radiation fluxes show the following trends: Q p declines continuously despite a slight increase of G p . This is mainly due to the long-wave radiation fluxes. The net radiation of the grass surface Q g shows noticeably lower values after the merging of the site. This phenomenon is also dominated by the long-wave radiation processes. Although the properties of both site surfaces alter, E p and E g remain relatively stable. A p and A g show a remarkable decrease however. The reason for this is to be found in a modification of the heat advection, showing a more pronounced impact on the more continentally exposed site (pine forest). Compared to α g , α p shows only a small

  11. Simulation of Solar Radiation Incident on Horizontal and Inclined Surfaces

    MA Basunia

    2012-12-01

    Full Text Available A computer model was developed to simulate the hourly, daily and monthly average of daily solar radiation on horizontal and inclined surfaces. The measured hourly and daily solar radiation was compared with simulated radiation, and favourable agreement was observed for the measured and predicted values on clear days. The measured and simulated monthly averages of total (diffuse and beam daily solar radiation were compared and a reasonable agreement was observed for a number of stations in Japan. The simulation showed that during the rice harvesting season, September to October, there is a daily average of 14.7 MJ/m2 of solar irradiation on a horizontal surface in Matsuyama, Japan. There is a similar amount of solar radiation on a horizontal surface during the major rice harvesting season, November to December, in Bangladesh. This radiation can be effectively utilized for drying rough rice and other farm crops.

  12. Investigations into radiation damages of reactor materials by computer simulation

    Bronnikov, V.A.

    2004-01-01

    Data on the state of works in European countries in the field of computerized simulation of radiation damages of reactor materials under the context of the international projects ITEM (European Database for Multiscale Modelling) and SIRENA (Simulation of Radiation Effects in Zr-Nb alloys) - computerized simulation of stress corrosion when contact of Zr-Nb alloys with iodine are presented. Computer codes for the simulation of radiation effects in reactor materials were developed. European Database for Multiscale Modelling (EDAM) was organized using the results of the investigations provided in the ITEM project [ru

  13. Galactic cosmic ray simulation at the NASA Space Radiation Laboratory

    Norbury, John W.; Schimmerling, Walter; Slaba, Tony C.; Azzam, Edouard I.; Badavi, Francis F.; Baiocco, Giorgio; Benton, Eric; Bindi, Veronica; Blakely, Eleanor A.; Blattnig, Steve R.; Boothman, David A.; Borak, Thomas B.; Britten, Richard A.; Curtis, Stan; Dingfelder, Michael; Durante, Marco; Dynan, William S.; Eisch, Amelia J.; Elgart, S. Robin; Goodhead, Dudley T.; Guida, Peter M.; Heilbronn, Lawrence H.; Hellweg, Christine E.; Huff, Janice L.; Kronenberg, Amy; La Tessa, Chiara; Lowenstein, Derek I.; Miller, Jack; Morita, Takashi; Narici, Livio; Nelson, Gregory A.; Norman, Ryan B.; Ottolenghi, Andrea; Patel, Zarana S.; Reitz, Guenther; Rusek, Adam; Schreurs, Ann-Sofie; Scott-Carnell, Lisa A.; Semones, Edward; Shay, Jerry W.; Shurshakov, Vyacheslav A.; Sihver, Lembit; Simonsen, Lisa C.; Story, Michael D.; Turker, Mitchell S.; Uchihori, Yukio; Williams, Jacqueline; Zeitlin, Cary J.

    2017-01-01

    Most accelerator-based space radiation experiments have been performed with single ion beams at fixed energies. However, the space radiation environment consists of a wide variety of ion species with a continuous range of energies. Due to recent developments in beam switching technology implemented at the NASA Space Radiation Laboratory (NSRL) at Brookhaven National Laboratory (BNL), it is now possible to rapidly switch ion species and energies, allowing for the possibility to more realistically simulate the actual radiation environment found in space. The present paper discusses a variety of issues related to implementation of galactic cosmic ray (GCR) simulation at NSRL, especially for experiments in radiobiology. Advantages and disadvantages of different approaches to developing a GCR simulator are presented. In addition, issues common to both GCR simulation and single beam experiments are compared to issues unique to GCR simulation studies. A set of conclusions is presented as well as a discussion of the technical implementation of GCR simulation. PMID:26948012

  14. Some results of simulation on radiation effects in crystals

    Baier, T.; AN SSSR, Novosibirsk

    1993-05-01

    Simulations concerning radiation in oriented silicon and tungsten crystals of different thicknesses are developed. Conditions are those of experiments done at Kharkov (Ukraine) and Tomsk (Russia) with electron beams in the 1 GeV range. Systematic comparisons between experimental and simulated spectra associated to real spectrum, radiation energy and angular distribution of the photons are developed. The ability of the simulation program to describe crystal effects in the considered energy range is analysed. (author) 11 refs.; 8 figs

  15. Strong seismic wave scattering beneath Kanto region derived from dense K-NET/KiK-net strong motion network and numerical simulation

    Takemura, S.; Yoshimoto, K.

    2013-12-01

    Observed seismograms, which consist of the high-frequency body waves through the low-velocity (LV) region at depth of 20-40 km beneath northwestern Chiba in Kanto, show strong peak delay and spindle shape of S waves. By analyzing dense seismic records from K-NET/KiK-net, such spindle-shape S waves are clearly observed in the frequency range of 1-8 Hz. In order to investigate a specific heterogeneous structure to generate such observations, we conduct 3-D finite-difference method (FDM) simulation using realistic heterogeneous models and compare the simulation results with dense strong motion array observations. Our 3-D simulation model is covering the zone 150 km by 64 km in horizontal directions and 75 km in vertical direction, which has been discretized with uniform grid size 0.05 km. We assume a layered background velocity structure, which includes basin structure, crust, mantle and subducting oceanic plate, base on the model proposed by Koketsu et al. (2008). In order to introduce the effect of seismic wave scattering, we assume a stochastic random velocity fluctuation in each layer. Random velocity fluctuations are characterized by exponential-type auto-correlation function (ACF) with correlation distance a = 3 km and rms value of fluctuation e = 0.05 in the upper crust, a = 3 km and e = 0.07 in the lower crust, a = 10 km and e = 0.02 in the mantle. In the subducting oceanic plate, we assume an anisotropic random velocity fluctuation characterized by exponential-type ACF with aH = 10 km in horizontal direction, aZ = 0.5 km in vertical direction and e = 0.02 (e.g., Furumura and Kennett, 2005). In addition, we assume a LV zone at northeastern part of Chiba with depth of 20-40 km (e.g., Matsubara et al., 2004). In the LV zone, random velocity fluctuation characterized by Gaussian-type ACF with a = 1 km and e = 0.07 is superposed on exponential-type ACF with a = 3 km and e = 0.07, in order to modulate the S-wave propagation in the dominant frequency range of

  16. Application of the Forhyd model to simulate net precipitation and intercepted water evaporation in forest canopies in Colombian amazonia

    Tellez Guio, Patricia; Boschell Villamarin, Francisco; Tobon Marin, Conrado

    2005-01-01

    Hydrologic simulation is a technique, which allows us to understand the relationships among hydrological, biological and ecological variables in an ecosystem. In this research, the FORHYD model is used to simulate the net precipitation and the water intercepted by the canopies of a mature forest, a 30-year old secondary forest, an 18-year old secondary forest, a 5-year old secondary forest, and a shifting cultivation plot, all located in Colombia's amazonia. The model calculates the water budget of the canopy by using the precipitation rates, canopy drainage and evaporation of the water intercepted by the canopy. This paper is the second one in a series of papers reporting the results of the research on the simulation of the hydrological fluxes in three different land use types of Colombian amazonia. The research was carried out in middle Caqueta of Colombian amazonia (northwest amazon basin). The FORHYD model was calibrated and validated by using field observations of the climate, net precipitation (PT), thoughtful (TH) and stem flow (ST), which were monitored during a period of 15 months from March 2001 to June 2002. These observations were used as both input variables and diagnostic variables to probe the model's precision to simulate field observations. Results showed that FORHYD simulates with a good precision the net precipitation and the evaporation of the water intercepted by the canopy. However, the model's precision depends on a good parameterization, which in turn depends on a good database of field observations. The model is a good tool for simulating the hydrological cycle and can be used to simulate critical scenarios of climate variability

  17. Numerical simulations of conjugate convection combined with surface thermal radiation using an Immersed-Boundary Method

    Favre, F.; Colomer, G.; Lehmkuhl, O.; Oliva, A.

    2016-01-01

    Dynamic and thermal interaction problems involving fluids and solids were studied through a finite volume-based Navier-Stokes solver, combined with immersed-boundary techniques and the net radiation method. Source terms were included in the momentum and energy equations to enforce the non-slip condition and the conjugate boundary condition including the radiative heat exchange. Code validation was performed through the simulation of two cases from the literature: conjugate natural convection in a square cavity with a conducting side wall; and a cubical cavity with conducting walls and a heat source. The accuracy of the methodology and the validation of the inclusion of moving bodies into the simulation was performed via a theoretical case (paper)

  18. Improved netting

    Bramley, A.; Clabburn, R.J.T.

    1976-01-01

    A method is described for producing netting composed of longitudinal and transverse threads of irradiation cross linked thermoplastic material, the threads being joined together at their crossings by moulded masses of cross linked thermoplastic material. The thread may be formed of polyethylene filaments, subjected to a radiation dose of 15 to 25 MR. The moulding can be conducted at 245 0 to 260 0 C or higher. The product is claimed to be an improved quality of netting, with bonds of increased strength between crossing threads. (U.K.)

  19. A Timed Colored Petri Net Simulation-Based Self-Adaptive Collaboration Method for Production-Logistics Systems

    Zhengang Guo; Yingfeng Zhang; Xibin Zhao; Xiaoyu Song

    2017-01-01

    Complex and customized manufacturing requires a high level of collaboration between production and logistics in a flexible production system. With the widespread use of Internet of Things technology in manufacturing, a great amount of real-time and multi-source manufacturing data and logistics data is created, that can be used to perform production-logistics collaboration. To solve the aforementioned problems, this paper proposes a timed colored Petri net simulation-based self-adaptive colla...

  20. Cloud radiative effects and changes simulated by the Coupled Model Intercomparison Project Phase 5 models

    Shin, Sun-Hee; Kim, Ok-Yeon; Kim, Dongmin; Lee, Myong-In

    2017-07-01

    Using 32 CMIP5 (Coupled Model Intercomparison Project Phase 5) models, this study examines the veracity in the simulation of cloud amount and their radiative effects (CREs) in the historical run driven by observed external radiative forcing for 1850-2005, and their future changes in the RCP (Representative Concentration Pathway) 4.5 scenario runs for 2006-2100. Validation metrics for the historical run are designed to examine the accuracy in the representation of spatial patterns for climatological mean, and annual and interannual variations of clouds and CREs. The models show large spread in the simulation of cloud amounts, specifically in the low cloud amount. The observed relationship between cloud amount and the controlling large-scale environment are also reproduced diversely by various models. Based on the validation metrics, four models—ACCESS1.0, ACCESS1.3, HadGEM2-CC, and HadGEM2-ES—are selected as best models, and the average of the four models performs more skillfully than the multimodel ensemble average. All models project global-mean SST warming at the increase of the greenhouse gases, but the magnitude varies across the simulations between 1 and 2 K, which is largely attributable to the difference in the change of cloud amount and distribution. The models that simulate more SST warming show a greater increase in the net CRE due to reduced low cloud and increased incoming shortwave radiation, particularly over the regions of marine boundary layer in the subtropics. Selected best-performing models project a significant reduction in global-mean cloud amount of about -0.99% K-1 and net radiative warming of 0.46 W m-2 K-1, suggesting a role of positive feedback to global warming.

  1. Mathematical model and simulations of radiation fluxes from buried radionuclides

    Ahmad Saat

    1999-01-01

    A mathematical model and a simple Monte Carlo simulations were developed to predict radiation fluxes from buried radionuclides. The model and simulations were applied to measured (experimental) data. The results of the mathematical model showed good acceptable order of magnitude agreement. A good agreement was also obtained between the simple simulations and the experimental results. Thus, knowing the radionuclide distribution profiles in soil from a core sample, it can be applied to the model or simulations to estimate the radiation fluxes emerging from the soil surface. (author)

  2. Effects of UVB radiation on net community production in the upper global ocean

    Garcia-Corral, Lara S.; Holding, Johnna M.; Carrillo-de-Albornoz, Paloma; Steckbauer, Alexandra; Pé rez-Lorenzo, Marí a; Navarro, Nuria; Serret, Pablo; Duarte, Carlos M.; Agusti, Susana

    2016-01-01

    Our results suggest that earlier estimates of NCP for surface communities, which were hitherto derived using materials blocking UVB radiation were biased, with the direction and magnitude of this bias depending on the metabolic status of the communities and the underwater penetration of UVB radiation.

  3. Net radiation of mountain cultivated Norway spruce [Picea abies (L.) Karst.] stand: evaluation of shortand long-wave radiation ratio

    Marková, I.; Marek, Michal V.

    2011-01-01

    Roč. 53, č. 2 (2011), s. 114-122 ISSN 0071-6677 Institutional research plan: CEZ:AV0Z60870520 Keywords : downward short- and long-wave radiation * upward short- and long-wave radiation * sun elevation * clearness index Subject RIV: GK - Forestry

  4. Plasma radiation in tokamak disruption simulation experiments

    Arkhipov, N.; Bakhtin, V.; Safronov, V.; Toporkov, D.; Vasenin, S.; Zhitlukhin, A.; Wuerz, H.

    1995-01-01

    Plasma impact results in sudden evaporation of divertor plate material and produces a plasma cloud which acts as a protective shield. The incoming energy flux is absorbed in the plasma shield and is converted mainly into radiation. Thus the radiative characteristics of the target plasma determine the dissipation of the incoming energy and the heat load at the target. Radiation of target plasma is studied at the two plasma gun facility 2MK-200 at Troitsk. Space- and time-resolved spectroscopy and time-integrated space-resolved calorimetry are employed as diagnostics. Graphite and tungsten samples are exposed to deuterium plasma streams. It is found that the radiative characteristics depend strongly on the target material. Tungsten plasma arises within 1 micros close to the surface and shows continuum radiation only. Expansion of tungsten plasma is restricted. For a graphite target the plasma shield is a mixture of carbon and deuterium. It expands along the magnetic field lines with a velocity of v = (3--4) 10 6 cm/s. The plasma shield is a two zone plasma with a hot low dense corona and a cold dense layer close to the target. The plasma corona emits intense soft x-ray (SXR) line radiation in the frequency range from 300--380 eV mainly from CV ions. It acts as effective dissipation system and converts volumetrically the incoming energy flux into SXR radiation

  5. Surface net solar radiation estimated from satellite measurements - Comparisons with tower observations

    Li, Zhanqing; Leighton, H. G.; Cess, Robert D.

    1993-01-01

    A parameterization that relates the reflected solar flux at the top of the atmosphere to the net solar flux at the surface in terms of only the column water vapor amount and the solar zenith angle was tested against surface observations. Net surface fluxes deduced from coincidental collocated satellite-measured radiances and from measurements from towers in Boulder during summer and near Saskatoon in winter have mean differences of about 2 W/sq m, regardless of whether the sky is clear or cloudy. Furthermore, comparisons between the net fluxes deduced from the parameterization and from surface measurements showed equally good agreement when the data were partitioned into morning and afternoon observations. This is in contrast to results from an empirical clear-sky algorithm that is unable to account adequately for the effects of clouds and that shows, at Boulder, a distinct morning to afternoon variation. It is also demonstrated that the parameterization may be applied to irradiances at the top of the atmosphere that have been temporally averaged. The good agreement between the results of the parameterization and surface measurements suggests that the algorithm is a useful tool for a variety of climate studies.

  6. Surface Net Solar Radiation Estimated from Satellite Measurements: Comparisons with Tower Observations

    Li, Zhanqing; Leighton, H. G.; Cess, Robert D.

    1993-01-01

    A parameterization that relates the reflected solar flux at the top of the atmosphere to the net solar flux at the surface in terms of only the column water vapor amount and the solar zenith angle was tested against surface observations. Net surface fluxes deduced from coincidental collocated satellite-measured radiances and from measurements from towers in Boulder during summer and near Saskatoon in winter have mean differences of about 2 W/sq m, regardless of whether the sky is clear or cloudy. Furthermore, comparisons between the net fluxes deduced from the parameterization and from surface measurements showed equally good agreement when the data were partitioned into morning and afternoon observations. This is in contrast to results from an empirical clear-sky algorithm that is unable to account adequately for the effects of clouds and that shows, at Boulder, a distinct morning to afternoon variation, which is presumably due to the predominance of different cloud types throughout the day. It is also demonstrated that the parameterization may be applied to irradiances at the top of the atmosphere that have been temporally averaged by using the temporally averaged column water vapor amount and the temporally averaged cosine of the solar zenith angle. The good agreement between the results of the parameterization and surface measurements suggests that the algorithm is a useful tool for a variety of climate studies.

  7. Low Simulated Radiation Limit for Runaway Greenhouse Climates

    Goldblatt, Colin; Robinson, Tyler D.; Zahnle, Kevin J.; Crisp, David

    2013-01-01

    Terrestrial planet atmospheres must be in long-term radiation balance, with solar radiation absorbed matched by thermal radiation emitted. For hot moist atmospheres, however, there is an upper limit on the thermal emission which is decoupled from the surface temperature. If net absorbed solar radiation exceeds this limit the planet will heat uncontrollably, the so-called \\runaway greenhouse". Here we show that a runaway greenhouse induced steam atmosphere may be a stable state for a planet with the same amount of incident solar radiation as Earth has today, contrary to previous results. We have calculated the clear-sky radiation limits at line-by-line spectral resolution for the first time. The thermal radiation limit is lower than previously reported (282 W/sq m rather than 310W/sq m) and much more solar radiation would be absorbed (294W/sq m rather than 222W/sq m). Avoiding a runaway greenhouse under the present solar constant requires that the atmosphere is subsaturated with water, and that cloud albedo forcing exceeds cloud greenhouse forcing. Greenhouse warming could in theory trigger a runaway greenhouse but palaeoclimate comparisons suggest that foreseeable increases in greenhouse gases will be insufficient to do this.

  8. Simulation of the removal of NET internal components with dynamic modeling software

    Becquet, M.; Crutzen, Y.R.; Farfaletti-Casali, F.

    1989-01-01

    The replacement of the internal plasma-facing components (first-wall and blanket segments) for maintenance or at the end of their lifetime is an important aspect of the design of the next European torus (NET) and of the remote handling procedures. The first phase of development of the design software tool INVDYN (inverse dynamics) is presented, which will allow optimization of the movements of the internal segments during replacement, taking into account inertial effects and structural deformations. A first analysis of the removal of one NET internal segment provides, for a defined trajectory, the required generalized forces that must be applied on the crane system

  9. Thermal radiators with embedded pulsating heat pipes: Infra-red thermography and simulations

    Hemadri, Vadiraj A.; Gupta, Ashish; Khandekar, Sameer

    2011-01-01

    With the aim of exploring potential applications of Pulsating Heat Pipes (PHP), for space/terrestrial sectors, experimental study of embedded PHP thermal radiators, having two different effective Biot numbers respectively, and subjected to conjugate heat transfer conditions on their surface, i.e., natural convection and radiation, has been carried out under different thermo-mechanical boundary conditions. High resolution infrared camera is used to obtain spatial temperature profiles of the radiators. To complement the experimental study, detailed 3D computational heat transfer simulation has also been undertaken. By embedding PHP structures, it was possible to make the net thermal resistance of the mild steel radiator plate equivalent to the aluminum radiator plate, in spite of the large difference in their respective thermal conductivities (k Al ∼ 4k MS ). The study reveals that embedded PHP structures can be beneficial only under certain boundary conditions. The degree of isothermalization achieved in these structures strongly depends on its effective Biot number. The relative advantage of embedded PHP is appreciably higher if the thermal conductivity of the radiator plate material itself is low. The study indicates that the effective thermal conductivity of embedded PHP structure is of the order of 400 W/mK to 2300 W/mK, depending on the operating conditions. - Research highlights: → Study of radiator plates with embedded Pulsating Heat Pipe by infrared thermography. → Radiator is subjected to natural convection and radiation boundary conditions. → Experimental study is supported by 3D simulation. → Effective thermal conductivity of PHPs of the order of 2000 W/mK is obtained. → Efficacy of embedded PHPs depends on the effective Biot number of the system.

  10. Simulating Nonequilibrium Radiation via Orthogonal Polynomial Refinement

    2015-01-07

    measured by the preprocessing time, computer memory space, and average query time. In many search procedures for the number of points np of a data set, a...analytic expression for the radiative flux density is possible by the commonly accepted local thermal equilibrium ( LTE ) approximation. A semi...Vol. 227, pp. 9463-9476, 2008. 10. Galvez, M., Ray-Tracing model for radiation transport in three-dimensional LTE system, App. Physics, Vol. 38

  11. Simulation study of transverse optical klystron radiation

    Xu Hongliang; Diao Caozheng; Liu Jinying; He Duohui; Jia Qika; Wang Xiangqi

    1997-01-01

    The radiation from a transverse optical klystron (TOK) is calculated by far field approximation equation and numerical integration, in which the effects of electron-beam emittance and energy spread are considered. Accurate electron-beam profiles have been experimentally determined and modeled by the Monte Carlo method. The calculated spectra illustrate the emittance of Hefei storage ring imposes on the spontaneous radiation of TOK

  12. Cosmological N -body simulations including radiation perturbations

    Brandbyge, Jacob; Rampf, Cornelius; Tram, Thomas

    2017-01-01

    CosmologicalN-body simulations are the standard tools to study the emergence of the observed large-scale structure of the Universe. Such simulations usually solve for the gravitational dynamics of matter within the Newtonian approximation, thus discarding general relativistic effects such as the ......CosmologicalN-body simulations are the standard tools to study the emergence of the observed large-scale structure of the Universe. Such simulations usually solve for the gravitational dynamics of matter within the Newtonian approximation, thus discarding general relativistic effects...

  13. Simulation of Net Infiltration for Present-Day and Potential Future Climates

    D. Levitt

    2004-11-09

    The purpose of this model report is to document the infiltration model used to estimate upper-bound, mean, and lower-bound spatially-distributed average annual net infiltration rates for present-day and potential future climates at Yucca Mountain, Nevada. Net infiltration is the component of infiltrated precipitation, snowmelt, or surface water run-on that has percolated below the zone of evapotranspiration as defined by the depth of the effective root zone. The estimates of net infiltration are primarily used for defining the upper boundary condition for the site-scale three-dimensional unsaturated zone (UZ) model. The UZ flow model is one of several process models abstracted by the total system performance assessment (TSPA) model used to evaluate performance of the repository at Yucca Mountain, Nevada. The net-infiltration model is important for assessing repository-system performance because output from this model provides the upper boundary condition for the UZ flow model used to generate flow fields; water percolating downward from the UZ will be the principal means by which radionuclides are potentially released to the saturated zone (SZ). The SZ is the principal pathway to the biosphere where the reasonably maximally exposed individual (RMEI) is exposed to radionuclides.

  14. Simulation of Net Infiltration for Present-Day and Potential Future Climates

    Levitt, D.

    2004-01-01

    The purpose of this model report is to document the infiltration model used to estimate upper-bound, mean, and lower-bound spatially-distributed average annual net infiltration rates for present-day and potential future climates at Yucca Mountain, Nevada. Net infiltration is the component of infiltrated precipitation, snowmelt, or surface water run-on that has percolated below the zone of evapotranspiration as defined by the depth of the effective root zone. The estimates of net infiltration are primarily used for defining the upper boundary condition for the site-scale three-dimensional unsaturated zone (UZ) model. The UZ flow model is one of several process models abstracted by the total system performance assessment (TSPA) model used to evaluate performance of the repository at Yucca Mountain, Nevada. The net-infiltration model is important for assessing repository-system performance because output from this model provides the upper boundary condition for the UZ flow model used to generate flow fields; water percolating downward from the UZ will be the principal means by which radionuclides are potentially released to the saturated zone (SZ). The SZ is the principal pathway to the biosphere where the reasonably maximally exposed individual (RMEI) is exposed to radionuclides

  15. A Timed Colored Petri Net Simulation-Based Self-Adaptive Collaboration Method for Production-Logistics Systems

    Zhengang Guo

    2017-03-01

    Full Text Available Complex and customized manufacturing requires a high level of collaboration between production and logistics in a flexible production system. With the widespread use of Internet of Things technology in manufacturing, a great amount of real-time and multi-source manufacturing data and logistics data is created, that can be used to perform production-logistics collaboration. To solve the aforementioned problems, this paper proposes a timed colored Petri net simulation-based self-adaptive collaboration method for Internet of Things-enabled production-logistics systems. The method combines the schedule of token sequences in the timed colored Petri net with real-time status of key production and logistics equipment. The key equipment is made ‘smart’ to actively publish or request logistics tasks. An integrated framework based on a cloud service platform is introduced to provide the basis for self-adaptive collaboration of production-logistics systems. A simulation experiment is conducted by using colored Petri nets (CPN Tools to validate the performance and applicability of the proposed method. Computational experiments demonstrate that the proposed method outperforms the event-driven method in terms of reductions of waiting time, makespan, and electricity consumption. This proposed method is also applicable to other manufacturing systems to implement production-logistics collaboration.

  16. Ambient UV-B radiation reduces PSII performance and net photosynthesis in high Arctic Salix arctica

    Albert, Kristian Rost; Mikkelsen, Teis Nørgaard; Ro-Poulsen, H.

    2011-01-01

    , nitrogen and UV-B absorbing compounds. Compared to a 60% reduced UV-B irradiance, the ambient solar UV-B reduced net photosynthesis in Salix arctica leaves fixed in the 45° position which exposed leaves to maximum natural irradiance. Also a reduced Calvin Cycle capacity was found, i.e. the maximum rate...... across position in the vegetation. These findings add to the evidence that the ambient solar UV-B currently is a significant stress factor for plants in high Arctic Greenland....

  17. Extended object-oriented Petri net model for mission reliability simulation of repairable PMS with common cause failures

    Wu, Xin-yang; Wu, Xiao-Yue

    2015-01-01

    Phased Mission Systems (PMS) have several phases with different success criteria. Generally, traditional analytical methods need to make some assumptions when they are applied for reliability evaluation and analysis of complex PMS, for example, the components are non-repairable or components are not subjected to common cause failures (CCF). However, the evaluation and analysis results may be inapplicable when the assumptions do not agree with practical situation. In this article, we propose an extended object-oriented Petri net (EOOPN) model for mission reliability simulation of repairable PMS with CCFs. Based on object-oriented Petri net (OOPN), EOOPN defines four reusable sub-models to depict PMS at system, phase, or component levels respectively, logic transitions to depict complex components reliability logics in a more readable form, and broadcast place to transmit shared information among components synchronously. After extension, EOOPN could deal with repairable PMS with both external and internal CCFs conveniently. The mission reliability modelling, simulation and analysis using EOOPN are illustrated by a PMS example. The results demonstrate that the proposed EOOPN model is effective. - Highlights: • EOOPN model was effective in reliability simulation for repairable PMS with CCFs. • EOOPN had modular and hierarchical structure. • New elements of EOOPN made the modelling process more convenient and friendlier. • EOOPN had better model reusability and readability than other PNs

  18. Effect of Shock-Induced Cavitation Bubble Collapse on the damage in the Simulated Perineuronal Net of the Brain.

    Wu, Yuan-Ting; Adnan, Ashfaq

    2017-07-13

    The purpose of this study is to conduct modeling and simulation to understand the effect of shock-induced mechanical loading, in the form of cavitation bubble collapse, on damage to the brain's perineuronal nets (PNNs). It is known that high-energy implosion due to cavitation collapse is responsible for corrosion or surface damage in many mechanical devices. In this case, cavitation refers to the bubble created by pressure drop. The presence of a similar damage mechanism in biophysical systems has long being suspected but not well-explored. In this paper, we use reactive molecular dynamics (MD) to simulate the scenario of a shock wave induced cavitation collapse within the perineuronal net (PNN), which is the near-neuron domain of a brain's extracellular matrix (ECM). Our model is focused on the damage in hyaluronan (HA), which is the main structural component of PNN. We have investigated the roles of cavitation bubble location, shockwave intensity and the size of a cavitation bubble on the structural evolution of PNN. Simulation results show that the localized supersonic water hammer created by an asymmetrical bubble collapse may break the hyaluronan. As such, the current study advances current knowledge and understanding of the connection between PNN damage and neurodegenerative disorders.

  19. Simulation of first-wall radiation effects

    Logan, C.M.; Anderson, J.D.; Hansen, L.F.

    1975-01-01

    Many of the effects induced in metals as a result of exposure to a radiation environment are intimately associated with the energy of primary recoil atoms (PKAs). Protons with an energy of 16 MeV closely reproduce the PKA energy spectrum which will be present at the first wall in a D--T fusion reactor and should therefore closely reproduce the radiation effects induced by PKAs in the first wall. A preliminary experiment with protons was conducted to measure the sputtering rate and to look for the phenomenon of chunk emission recently observed by Kaminsky and co-workers in samples exposed to 14-MeV neutrons. We are also able to observe the average projected transport range of activated PKAs. (U.S.)

  20. Simulation and radiation treatment in external radiotherapy

    Singer, E [Mevaterapia Medical Center, Buenos Aires (Argentina)

    1996-08-01

    It is well known that in order to obtain a uniform dose in the treated volume as defined in ICRU 50, there should be a 10% maximum difference between maximum and minimum dose values in treatment planning. Clinical target volume (CTV) should be related to external areas of body sections where tumour is located. These areas are important because different radiation beams enter through them. Therefore, verification of the planning target volume (PTV) through the external areas is highly significant. In this work we point out the importance of controlling that PTV is irradiated as planned considering some error sources usually found in radiotherapy practice with equipment that has been intensively used for a long time. Moreover, I think this experience will be helpful for those centers around the world where radiation treatment is carried out with reconditioned units. (author).

  1. Simulation and radiation treatment in external radiotherapy

    Singer, E.

    1996-01-01

    It is well known that in order to obtain a uniform dose in the treated volume as defined in ICRU 50, there should be a 10% maximum difference between maximum and minimum dose values in treatment planning. Clinical target volume (CTV) should be related to external areas of body sections where tumour is located. These areas are important because different radiation beams enter through them. Therefore, verification of the planning target volume (PTV) through the external areas is highly significant. In this work we point out the importance of controlling that PTV is irradiated as planned considering some error sources usually found in radiotherapy practice with equipment that has been intensively used for a long time. Moreover, I think this experience will be helpful for those centers around the world where radiation treatment is carried out with reconditioned units. (author)

  2. Simulating nonthermal radiation from cluster radio galaxies.

    Tregillis, I. L. (Ian L.); Jones, T. W. (Thomas Walter); Ryu, Dongsu

    2004-01-01

    We present results from an extensive synthetic observation analysis of numerically-simulated radio galaxy (RG) jets. This analysis is based on the first three-dimensional simulations to treat cosmic ray acceleration and transport self-consistently within a magnetohydrodynamical calculation. We use standard observational techniques to calculate both minimum-energy and inverse-Compton field values for our simulated objects. The latter technique provides meaningful information about the field. Minimum-energy calculations retrieve reasonable field estimates in regions physically close to the minimum-energy partitioning, though the technique is highly susceptible to deviations from the underlying assumptions. We also study the reliability of published rotation measure analysis techniques. We find that gradient alignment statistics accurately reflect the physical situation, and can uncover otherwise hidden information about the source. Furthermore, correlations between rotation measure (RM) and position angle (PA) can be significant even when the RM is completely dominated by an external cluster medium.

  3. Modification of Sunlight Radiation through Colored Photo-Selective Nets Affects Anthocyanin Profile in Vaccinium spp. Berries.

    Laura Zoratti

    Full Text Available In recent years, the interest on the effects of the specific wavelengths of the light spectrum on growth and metabolism of plants has been increasing markedly. The present study covers the effect of modified sunlight conditions on the accumulation of anthocyanin pigments in two Vaccinium species: the European wild bilberry (V. myrtillus L. and the cultivated highbush blueberry (V. corymbosum L..The two Vaccinium species were grown in the same test field in the Alps of Trentino (Northern Italy under modified light environment. The modification of sunlight radiation was carried out in field, through the use of colored photo-selective nets throughout the berry ripening during two consecutive growing seasons. The anthocyanin profile was then assessed in berries at ripeness.The results indicated that the light responses of the two Vaccinium species studied were different. Although both studied species are shade-adapted plants, 90% shading of sunlight radiation was beneficial only for bilberry plants, which accumulated the highest content of anthocyanins in both seasons. The same condition, instead, was not favorable for blueberries, whose maturation was delayed for at least two weeks, and anthocyanin accumulation was significantly decreased compared to berries grown under sunlight conditions. Moreover, the growing season had strong influence on the anthocyanin accumulation in both species, in relation to temperature flow and sunlight spectra composition during the berry ripening period.Our results suggest that the use of colored photo-selective nets may be a complementary agricultural practice for cultivation of Vaccinium species. However, further studies are needed to analyze the effect of the light spectra modifications to other nutritional properties, and to elucidate the molecular mechanisms behind the detected differences between the two relative Vaccinium species.

  4. Modification of Sunlight Radiation through Colored Photo-Selective Nets Affects Anthocyanin Profile in Vaccinium spp. Berries.

    Zoratti, Laura; Jaakola, Laura; Häggman, Hely; Giongo, Lara

    2015-01-01

    In recent years, the interest on the effects of the specific wavelengths of the light spectrum on growth and metabolism of plants has been increasing markedly. The present study covers the effect of modified sunlight conditions on the accumulation of anthocyanin pigments in two Vaccinium species: the European wild bilberry (V. myrtillus L.) and the cultivated highbush blueberry (V. corymbosum L.). The two Vaccinium species were grown in the same test field in the Alps of Trentino (Northern Italy) under modified light environment. The modification of sunlight radiation was carried out in field, through the use of colored photo-selective nets throughout the berry ripening during two consecutive growing seasons. The anthocyanin profile was then assessed in berries at ripeness. The results indicated that the light responses of the two Vaccinium species studied were different. Although both studied species are shade-adapted plants, 90% shading of sunlight radiation was beneficial only for bilberry plants, which accumulated the highest content of anthocyanins in both seasons. The same condition, instead, was not favorable for blueberries, whose maturation was delayed for at least two weeks, and anthocyanin accumulation was significantly decreased compared to berries grown under sunlight conditions. Moreover, the growing season had strong influence on the anthocyanin accumulation in both species, in relation to temperature flow and sunlight spectra composition during the berry ripening period. Our results suggest that the use of colored photo-selective nets may be a complementary agricultural practice for cultivation of Vaccinium species. However, further studies are needed to analyze the effect of the light spectra modifications to other nutritional properties, and to elucidate the molecular mechanisms behind the detected differences between the two relative Vaccinium species.

  5. Absorbed radiation by various tissues during simulated endodontic radiography

    Torabinejad, M.; Danforth, R.; Andrews, K.; Chan, C.

    1989-01-01

    The amount of absorbed radiation by various organs was determined by placing lithium fluoride thermoluminescent chip dosimeters at selected anatomical sites in and on a human-like X-ray phantom and exposing them to radiation at 70- and 90-kV X-ray peaks during simulated endodontic radiography. The mean exposure dose was determined for each anatomical site. The results show that endodontic X-ray doses received by patients are low when compared with other radiographic procedures

  6. Applications Of Monte Carlo Radiation Transport Simulation Techniques For Predicting Single Event Effects In Microelectronics

    Warren, Kevin; Reed, Robert; Weller, Robert; Mendenhall, Marcus; Sierawski, Brian; Schrimpf, Ronald

    2011-01-01

    MRED (Monte Carlo Radiative Energy Deposition) is Vanderbilt University's Geant4 application for simulating radiation events in semiconductors. Geant4 is comprised of the best available computational physics models for the transport of radiation through matter. In addition to basic radiation transport physics contained in the Geant4 core, MRED has the capability to track energy loss in tetrahedral geometric objects, includes a cross section biasing and track weighting technique for variance reduction, and additional features relevant to semiconductor device applications. The crucial element of predicting Single Event Upset (SEU) parameters using radiation transport software is the creation of a dosimetry model that accurately approximates the net collected charge at transistor contacts as a function of deposited energy. The dosimetry technique described here is the multiple sensitive volume (MSV) model. It is shown to be a reasonable approximation of the charge collection process and its parameters can be calibrated to experimental measurements of SEU cross sections. The MSV model, within the framework of MRED, is examined for heavy ion and high-energy proton SEU measurements of a static random access memory.

  7. Estimating net surface shortwave radiation from Chinese geostationary meteorological satellite FengYun-2D (FY-2D) data under clear sky.

    Zhang, Xiaoyu; Li, Lingling

    2016-03-21

    Net surface shortwave radiation (NSSR) significantly affects regional and global climate change, and is an important aspect of research on surface radiation budget balance. Many previous studies have proposed methods for estimating NSSR. This study proposes a method to calculate NSSR using FY-2D short-wave channel data. Firstly, a linear regression model is established between the top-of-atmosphere (TOA) broadband albedo (r) and the narrowband reflectivity (ρ1), based on data simulated with MODTRAN 4.2. Secondly, the relationship between surface absorption coefficient (as) and broadband albedo (r) is determined by dividing the surface type into land, sea, or snow&ice, and NSSR can then be calculated. Thirdly, sensitivity analysis is performed for errors associated with sensor noise, vertically integrated atmospheric water content, view zenith angle and solar zenith angle. Finally, validation using ground measurements is performed. Results show that the root mean square error (RMSE) between the estimated and actual r is less than 0.011 for all conditions, and the RMSEs between estimated and real NSSR are 26.60 W/m2, 9.99 W/m2, and 23.40 W/m2, using simulated data for land, sea, and snow&ice surfaces, respectively. This indicates that the proposed method can be used to adequately estimate NSSR. Additionally, we compare field measurements from TaiYuan and ChangWu ecological stations with estimates using corresponding FY-2D data acquired from January to April 2012, on cloud-free days. Results show that the RMSE between the estimated and actual NSSR is 48.56W/m2, with a mean error of -2.23W/m2. Causes of errors also include measurement accuracy and estimations of atmospheric water vertical contents. This method is only suitable for cloudless conditions.

  8. On the elimination of numerical Cerenkov radiation in PIC simulations

    Greenwood, Andrew D.; Cartwright, Keith L.; Luginsland, John W.; Baca, Ernest A.

    2004-01-01

    Particle-in-cell (PIC) simulations are a useful tool in modeling plasma in physical devices. The Yee finite difference time domain (FDTD) method is commonly used in PIC simulations to model the electromagnetic fields. However, in the Yee FDTD method, poorly resolved waves at frequencies near the cut off frequency of the grid travel slower than the physical speed of light. These slowly traveling, poorly resolved waves are not a problem in many simulations because the physics of interest are at much lower frequencies. However, when high energy particles are present, the particles may travel faster than the numerical speed of their own radiation, leading to non-physical, numerical Cerenkov radiation. Due to non-linear interaction between the particles and the fields, the numerical Cerenkov radiation couples into the frequency band of physical interest and corrupts the PIC simulation. There are two methods of mitigating the effects of the numerical Cerenkov radiation. The computational stencil used to approximate the curl operator can be altered to improve the high frequency physics, or a filtering scheme can be introduced to attenuate the waves that cause the numerical Cerenkov radiation. Altering the computational stencil is more physically accurate but is difficult to implement while maintaining charge conservation in the code. Thus, filtering is more commonly used. Two previously published filters by Godfrey and Friedman are analyzed and compared to ideally desired filter properties

  9. Early decision support for net zero energy buildings design using building performance simulation

    Attia, S.G.; Gratia, E.; De Herde, A.; Hensen, J.L.M.

    2013-01-01

    This paper aims to investigate the use of building performance simulation tools as a method of informing the design decision of NZEBs. The aim of this study is to evaluate the effect of a simulation-based decision aid, ZEBO, on informed decision-making using sensitivity analysis. The objective is to

  10. Computer simulations of radiation damage in protein crystals

    Zehnder, M.

    2007-03-01

    The achievable resolution and the quality of the dataset of an intensity data collection for structure analysis of protein crystals with X-rays is limited among other factors by radiation damage. The aim of this work is to obtain a better quantitative understanding of the radiation damage process in proteins. Since radiation damage is unavoidable it was intended to look for the optimum ratio between elastically scattered intensity and radiation damage. Using a Monte Carlo algorithm physical processes after an inelastic photon interaction are studied. The main radiation damage consists of ionizations of the atoms through the electron cascade following any inelastic photon interaction. Results of the method introduced in this investigation and results of an earlier theoretical studies of the influence of Auger-electron transport in diamond are in a good agreement. The dependence of the radiation damage as a function of the energy of the incident photon was studied by computer-aided simulations. The optimum energy range for diffraction experiments on the protein myoglobin is 10-40 keV. Studies of radiation damage as a function of crystal volume and shape revealed that very small plate or rod shaped crystals suffer less damage than crystals formed like a cube with the same volume. Furthermore the influence of a few heavy atoms in the protein molecule on radiation damage was examined. Already two iron atoms in the unit cell of myoglobin increase radiation damage significantly. (orig.)

  11. Computer simulation of ionizing radiation burnout in power MOSFETs

    Keshavarz, A.A.; Fischer, T.A.; Dawes, W.R. Jr.; Hawkins, C.F.

    1988-01-01

    The transient response of a power MOSFET device to ionizing radiation was examined using the BAMBI device simulator. The radiation rate threshold for burnout was determined for several different cases. The burnout mechanism was attributed to current-induced avalanche. The effects of the applied drain-source voltage and the base width of the parasitic bipolar device on the threshold level were modeled. It was found that the radiation rate threshold is lower at higher drain-source voltages or narrower bases. 8 refs., 17 figs

  12. Radiative and convective properties of 316L Stainless Steel fabricated using the Laser Engineered Net Shaping process

    Knopp, Jonathan

    Temperature evolution of metallic materials during the additive manufacturing process has direct influence in determining the materials microstructure and resultant characteristics. Through the power of Infrared (IR) thermography it is now possible to monitor thermal trends in a build structure, giving the power to adjust building parameters in real time. The IR camera views radiation in the IR wavelengths and determines temperature of an object by the amount of radiation emitted from the object in those wavelengths. Determining the amount of radiation emitted from the material, known as a materials emissivity, can be difficult in that emissivity is affected by both temperature and surface finish. It has been shown that the use of a micro-blackbody cavity can be used as an accurate reference temperature when the sample is held at thermal equilibrium. A micro-blackbody cavity was created in a sample of 316L Stainless Steel after being fabricated during using the Laser Engineered Net Shaping (LENS) process. Holding the sample at thermal equilibrium and using the micro-blackbody cavity as a reference and thermocouple as a second reference emissivity values were able to be obtained. IR thermography was also used to observe the manufacturing of these samples. When observing the IR thermography, patterns in the thermal history of the build were shown to be present as well as distinct cooling rates of the material. This information can be used to find true temperatures of 316L Stainless Steel during the LENS process for better control of desired material properties as well as future work in determining complete energy balance.

  13. [Parameter sensitivity of simulating net primary productivity of Larix olgensis forest based on BIOME-BGC model].

    He, Li-hong; Wang, Hai-yan; Lei, Xiang-dong

    2016-02-01

    Model based on vegetation ecophysiological process contains many parameters, and reasonable parameter values will greatly improve simulation ability. Sensitivity analysis, as an important method to screen out the sensitive parameters, can comprehensively analyze how model parameters affect the simulation results. In this paper, we conducted parameter sensitivity analysis of BIOME-BGC model with a case study of simulating net primary productivity (NPP) of Larix olgensis forest in Wangqing, Jilin Province. First, with the contrastive analysis between field measurement data and the simulation results, we tested the BIOME-BGC model' s capability of simulating the NPP of L. olgensis forest. Then, Morris and EFAST sensitivity methods were used to screen the sensitive parameters that had strong influence on NPP. On this basis, we also quantitatively estimated the sensitivity of the screened parameters, and calculated the global, the first-order and the second-order sensitivity indices. The results showed that the BIOME-BGC model could well simulate the NPP of L. olgensis forest in the sample plot. The Morris sensitivity method provided a reliable parameter sensitivity analysis result under the condition of a relatively small sample size. The EFAST sensitivity method could quantitatively measure the impact of simulation result of a single parameter as well as the interaction between the parameters in BIOME-BGC model. The influential sensitive parameters for L. olgensis forest NPP were new stem carbon to new leaf carbon allocation and leaf carbon to nitrogen ratio, the effect of their interaction was significantly greater than the other parameter' teraction effect.

  14. Simulating Space Radiation-Induced Breast Tumor Incidence Using Automata.

    Heuskin, A C; Osseiran, A I; Tang, J; Costes, S V

    2016-07-01

    Estimating cancer risk from space radiation has been an ongoing challenge for decades primarily because most of the reported epidemiological data on radiation-induced risks are derived from studies of atomic bomb survivors who were exposed to an acute dose of gamma rays instead of chronic high-LET cosmic radiation. In this study, we introduce a formalism using cellular automata to model the long-term effects of ionizing radiation in human breast for different radiation qualities. We first validated and tuned parameters for an automata-based two-stage clonal expansion model simulating the age dependence of spontaneous breast cancer incidence in an unexposed U.S. We then tested the impact of radiation perturbation in the model by modifying parameters to reflect both targeted and nontargeted radiation effects. Targeted effects (TE) reflect the immediate impact of radiation on a cell's DNA with classic end points being gene mutations and cell death. They are well known and are directly derived from experimental data. In contrast, nontargeted effects (NTE) are persistent and affect both damaged and undamaged cells, are nonlinear with dose and are not well characterized in the literature. In this study, we introduced TE in our model and compared predictions against epidemiologic data of the atomic bomb survivor cohort. TE alone are not sufficient for inducing enough cancer. NTE independent of dose and lasting ∼100 days postirradiation need to be added to accurately predict dose dependence of breast cancer induced by gamma rays. Finally, by integrating experimental relative biological effectiveness (RBE) for TE and keeping NTE (i.e., radiation-induced genomic instability) constant with dose and LET, the model predicts that RBE for breast cancer induced by cosmic radiation would be maximum at 220 keV/μm. This approach lays the groundwork for further investigation into the impact of chronic low-dose exposure, inter-individual variation and more complex space radiation

  15. Simulation of Net Primary Productivity in Mongolia Using CASA Model, During 2000-2004

    Narangarav Dugarsuren

    2016-12-01

    Full Text Available Vegetation net primary productivity (NPP is always used as an indicator of carbon cycling in terrestrial ecosystems at landscape and regional scales. Based on the CASA model, we analyzed the spatiotemporal pattern of growing season NPP from 2000 to 2004 using MODIS/NDVI and its relationship with precipitation. The result shows that the annual NPP in Mongolia has a tendency to slightly decrease from 61.13 in 2000 to 60 gC/m2 /yr in 2004, with an annual mean decrement of -0.259 gC/ m2 /yr. However, annual and inter-annual NPP trends showed spatial and temporal heterogeneity. NPP in forest and grassland has decreased with an average annual decrement of -1.03 (r2=0.262 and -0.49 (r2=0.324, meanwhile NPP in desert steppe and desert has increased with the annual average increment of 0.4327 (r2=0.322 and 0.2401 (r2=0.283, respectively. The correlation coeffi cient showed that mean growing season NPP in grassland and desert steppe were closely correlated with precipitation than forest and desert.

  16. Simulated radiation disinfestation of infested cocoa beans in Ghana

    Amoako-Atta, B.

    1979-01-01

    Four major insect pests persistently affect the cocoa industry in Ghana, the world's leading exporter of cocoa, despite the conventional methods of chemical control in practice. The Ghana Atomic Energy Commission currently is investigating the possible use of radiation for the control of both insect attack and microbial spoilage of cocoa beans in storage. Radiation response studies of the four major insect pests that significantly affect the quality of dried cocoa beans in storage have been evaluated. Results herein reported were based on simulated bulk infestation radiation disinfestation of dried cocoa under field and laboratory conditions at ambient temperature (25 to 32 0 C). The comparative efficiency of locally available packaging materials best suited for bagging of the dried cocoa beans at and after irradiation have been assessed concurrently. The author concludes by identifying and discussing possible factors that could affect the technology of radiation disinfestation of cocoa beans under the Ghanaian context. (author)

  17. Simulation of non LTE opacity with incoming radiation

    Klapisch, Marcel; Busquet, Michel

    2009-11-01

    Simulation of radiative properties of hot plasmas is important for ICF, other laboratory plasmas, and astrophysics. When mid-Z or high-Z elements are involved, the spectra are so complex that one commonly uses LTE approximation. This was recently done in interpreting a carefully calibrated experiment on Fe at 160 eV [1]. However some disagreement remains concerning the ion charge distribution. The newest version of HULLAC [2] has the capability to take into account an incoming radiation field in solving the rate equations of the coronal radiative model (CRM). We will show results with different representation of the radiation field.[4pt] [1] J.E. Bailey, G.A. Rochau, C.A. Iglesias, et al., Phys. Rev. Lett. 99, (2007) 265002-4.[0pt] [2] M. Klapisch and M. Busquet, High Ener. Dens. Phys. 5, (2009) 105-9.

  18. Finite element simulation of HIP-process to produce 3d near net shape parts

    Zadeh, M.K.

    1996-01-01

    One of the major problems when producing powder metallurgy parts through hot isostatic pressing (HIP) is the non homogeneous shrinkage of HIP-capsule during the process. This leads to time and cost consuming machining of the HIP parts. In order to reduce the machining to a minimum, one can try to simulate the HIP-process by means of numerical methods. Hereby, the part distortion can be predicted, and hence a new HIP-capsule can be designed in such a way to prevent the distortion partly or even completely. In the following, a finite element method is used, on one hand, to simulate part shrinkage during HIP process; on the other hand a method is integrated in this simulation to optimize the HIP-capsule geometry. For the determination of material dependent parameters, a mixture of theoretical and experimental methods is used. Results of simulation are verified for a complex 3d HIP part out of TiAl6V4

  19. Petri Net and Probabilistic Model Checking Based Approach for the Modelling, Simulation and Verification of Internet Worm Propagation.

    Misbah Razzaq

    Full Text Available Internet worms are analogous to biological viruses since they can infect a host and have the ability to propagate through a chosen medium. To prevent the spread of a worm or to grasp how to regulate a prevailing worm, compartmental models are commonly used as a means to examine and understand the patterns and mechanisms of a worm spread. However, one of the greatest challenge is to produce methods to verify and validate the behavioural properties of a compartmental model. This is why in this study we suggest a framework based on Petri Nets and Model Checking through which we can meticulously examine and validate these models. We investigate Susceptible-Exposed-Infectious-Recovered (SEIR model and propose a new model Susceptible-Exposed-Infectious-Recovered-Delayed-Quarantined (Susceptible/Recovered (SEIDQR(S/I along with hybrid quarantine strategy, which is then constructed and analysed using Stochastic Petri Nets and Continuous Time Markov Chain. The analysis shows that the hybrid quarantine strategy is extremely effective in reducing the risk of propagating the worm. Through Model Checking, we gained insight into the functionality of compartmental models. Model Checking results validate simulation ones well, which fully support the proposed framework.

  20. Status Report of Simulated Space Radiation Environment Facility

    Kang, Phil Hyun; Nho, Young Chang; Jeun, Joon Pyo; Choi, Jae Hak; Lim, Youn Mook; Jung, Chan Hee; Jeon, Young Kyu

    2007-11-15

    The technology for performance testing and improvement of materials which are durable at space environment is a military related technology and veiled and securely regulated in advanced countries such as US and Russia. This core technology cannot be easily transferred to other country too. Therefore, this technology is the most fundamental and necessary research area for the successful establishment of space environment system. Since the task for evaluating the effects of space materials and components by space radiation plays important role in satellite lifetime extension and running failure percentage decrease, it is necessary to establish simulated space radiation facility and systematic testing procedure. This report has dealt with the status of the technology to enable the simulation of space environment effects, including the effect of space radiation on space materials. This information such as the fundamental knowledge of space environment and research status of various countries as to the simulation of space environment effects of space materials will be useful for the research on radiation hardiness of the materials. Furthermore, it will be helpful for developer of space material on deriving a better choice of materials, reducing the design cycle time, and improving safety.

  1. Status Report of Simulated Space Radiation Environment Facility

    Kang, Phil Hyun; Nho, Young Chang; Jeun, Joon Pyo; Choi, Jae Hak; Lim, Youn Mook; Jung, Chan Hee; Jeon, Young Kyu

    2007-11-01

    The technology for performance testing and improvement of materials which are durable at space environment is a military related technology and veiled and securely regulated in advanced countries such as US and Russia. This core technology cannot be easily transferred to other country too. Therefore, this technology is the most fundamental and necessary research area for the successful establishment of space environment system. Since the task for evaluating the effects of space materials and components by space radiation plays important role in satellite lifetime extension and running failure percentage decrease, it is necessary to establish simulated space radiation facility and systematic testing procedure. This report has dealt with the status of the technology to enable the simulation of space environment effects, including the effect of space radiation on space materials. This information such as the fundamental knowledge of space environment and research status of various countries as to the simulation of space environment effects of space materials will be useful for the research on radiation hardiness of the materials. Furthermore, it will be helpful for developer of space material on deriving a better choice of materials, reducing the design cycle time, and improving safety

  2. Bridging the Gap between ABM and MAS: A Disaster-Rescue Simulation Using Jason and NetLogo

    Wulfrano Arturo Luna-Ramirez

    2018-04-01

    Full Text Available An agent is an autonomous computer system situated in an environment to fulfill a design objective. Multi-Agent Systems aim to solve problems in a flexible and robust way by assembling sets of agents interacting in cooperative or competitive ways for the sake of possibly common objectives. Multi-Agent Systems have been applied to several domains ranging from many industrial sectors, e-commerce, health and even entertainment. Agent-Based Modeling, a sort of Multi-Agent Systems, is a technique used to study complex systems in a wide range of domains. A natural or social system can be represented, modeled and explained through a simulation based on agents and interactions. Such a simulation can comprise a variety of agent architectures like reactive and cognitive agents. Despite cognitive agents being highly relevant to simulate social systems due their capability of modelling aspects of human behaviour ranging from individuals to crowds, they still have not been applied extensively. A challenging and socially relevant domain are the Disaster-Rescue simulations that can benefit from using cognitive agents to develop a realistic simulation. In this paper, a Multi-Agent System applied to the Disaster-Rescue domain involving cognitive agents based on the Belief–Desire–Intention architecture is presented. The system aims to bridge the gap in combining Agent-Based Modelling and Multi-Agent Systems approaches by integrating two major platforms in the field of Agent-Based Modeling and Belief-Desire Intention multi-agent systems, namely, NetLogo and Jason.

  3. Monte Carlo simulation of radiation treatment machine heads

    Mohan, R.

    1988-01-01

    Monte Carlo simulations of radiation treatment machine heads provide practical means for obtaining energy spectra and angular distributions of photons and electrons. So far, most of the work published in the literature has been limited to photons and the contaminant electrons knocked out by photons. This chapter will be confined to megavoltage photon beams produced by medical linear accelerators and 60 Co teletherapy units. The knowledge of energy spectra and angular distributions of photons and contaminant electrons emerging from such machines is important for a variety of applications in radiation dosimetry

  4. Modeling, Analysis and Simulation of Simple One Machine-Two Product System Using Petri Nets = Basit Bir Makine-İki Ürün Sisteminin Petri Ağları Kullanılarak Modellenmesi, Analizi ve Simulasyonu

    Özgür ARMANERİ

    2006-01-01

    Full Text Available As in many engineering fields, the design of manufacturing systems can be carried out using models. Petri nets have been used extensively to model and analyze manufacturing systems. Petri Nets, as graphical and mathematical tools, provide a uniform environment for modeling, format analysis and design of discrete event systems. The modeling, simulation and analysis of simple one machine-two product systems using Petri nets will be presented in this paper. Behavioral and structural properties of the Petri net model will be considered in details. Then, the Petri net model of one machine-two product system will be simulated using a simulation program.

  5. Automatic CT simulation optimization for radiation therapy: A general strategy.

    Li, Hua; Yu, Lifeng; Anastasio, Mark A; Chen, Hsin-Chen; Tan, Jun; Gay, Hiram; Michalski, Jeff M; Low, Daniel A; Mutic, Sasa

    2014-03-01

    In radiation therapy, x-ray computed tomography (CT) simulation protocol specifications should be driven by the treatment planning requirements in lieu of duplicating diagnostic CT screening protocols. The purpose of this study was to develop a general strategy that allows for automatically, prospectively, and objectively determining the optimal patient-specific CT simulation protocols based on radiation-therapy goals, namely, maintenance of contouring quality and integrity while minimizing patient CT simulation dose. The authors proposed a general prediction strategy that provides automatic optimal CT simulation protocol selection as a function of patient size and treatment planning task. The optimal protocol is the one that delivers the minimum dose required to provide a CT simulation scan that yields accurate contours. Accurate treatment plans depend on accurate contours in order to conform the dose to actual tumor and normal organ positions. An image quality index, defined to characterize how simulation scan quality affects contour delineation, was developed and used to benchmark the contouring accuracy and treatment plan quality within the predication strategy. A clinical workflow was developed to select the optimal CT simulation protocols incorporating patient size, target delineation, and radiation dose efficiency. An experimental study using an anthropomorphic pelvis phantom with added-bolus layers was used to demonstrate how the proposed prediction strategy could be implemented and how the optimal CT simulation protocols could be selected for prostate cancer patients based on patient size and treatment planning task. Clinical IMRT prostate treatment plans for seven CT scans with varied image quality indices were separately optimized and compared to verify the trace of target and organ dosimetry coverage. Based on the phantom study, the optimal image quality index for accurate manual prostate contouring was 4.4. The optimal tube potentials for patient sizes

  6. Automatic CT simulation optimization for radiation therapy: A general strategy

    Li, Hua, E-mail: huli@radonc.wustl.edu; Chen, Hsin-Chen; Tan, Jun; Gay, Hiram; Michalski, Jeff M.; Mutic, Sasa [Department of Radiation Oncology, Washington University, St. Louis, Missouri 63110 (United States); Yu, Lifeng [Department of Radiology, Mayo Clinic, Rochester, Minnesota 55905 (United States); Anastasio, Mark A. [Department of Biomedical Engineering, Washington University, St. Louis, Missouri 63110 (United States); Low, Daniel A. [Department of Radiation Oncology, University of California Los Angeles, Los Angeles, California 90095 (United States)

    2014-03-15

    Purpose: In radiation therapy, x-ray computed tomography (CT) simulation protocol specifications should be driven by the treatment planning requirements in lieu of duplicating diagnostic CT screening protocols. The purpose of this study was to develop a general strategy that allows for automatically, prospectively, and objectively determining the optimal patient-specific CT simulation protocols based on radiation-therapy goals, namely, maintenance of contouring quality and integrity while minimizing patient CT simulation dose. Methods: The authors proposed a general prediction strategy that provides automatic optimal CT simulation protocol selection as a function of patient size and treatment planning task. The optimal protocol is the one that delivers the minimum dose required to provide a CT simulation scan that yields accurate contours. Accurate treatment plans depend on accurate contours in order to conform the dose to actual tumor and normal organ positions. An image quality index, defined to characterize how simulation scan quality affects contour delineation, was developed and used to benchmark the contouring accuracy and treatment plan quality within the predication strategy. A clinical workflow was developed to select the optimal CT simulation protocols incorporating patient size, target delineation, and radiation dose efficiency. An experimental study using an anthropomorphic pelvis phantom with added-bolus layers was used to demonstrate how the proposed prediction strategy could be implemented and how the optimal CT simulation protocols could be selected for prostate cancer patients based on patient size and treatment planning task. Clinical IMRT prostate treatment plans for seven CT scans with varied image quality indices were separately optimized and compared to verify the trace of target and organ dosimetry coverage. Results: Based on the phantom study, the optimal image quality index for accurate manual prostate contouring was 4.4. The optimal tube

  7. Theoretic simulation for CMOS device on total dose radiation response

    He Baoping; Zhou Heqin; Guo Hongxia; He Chaohui; Zhou Hui; Luo Yinhong; Zhang Fengqi

    2006-01-01

    Total dose effect is simulated for C4007B, CC4007RH and CC4011 devices at different absorbed dose rate by using linear system theory. When irradiation response and dose are linear, total dose radiation and post-irradiation annealing at room temperature are determined for one random by choosing absorbed dose rate, and total dose effect at other absorbed dose rate can be predicted by using linear system theory. The simulating results agree with the experimental results at different absorbed dose rate. (authors)

  8. Molecular dynamics simulation of radiation damage cascades in diamond

    Buchan, J. T. [Department of Physics and Astronomy, Curtin University, Perth, Western Australia 6845 (Australia); Robinson, M. [Nanochemistry Research Institute, Curtin University, Perth, Western Australia 6845 (Australia); Christie, H. J.; Roach, D. L.; Ross, D. K. [Physics and Materials Research Centre, School of Computing, Science and Engineering, University of Salford, Salford, Greater Manchester M5 4WT (United Kingdom); Marks, N. A. [Department of Physics and Astronomy, Curtin University, Perth, Western Australia 6845 (Australia); Nanochemistry Research Institute, Curtin University, Perth, Western Australia 6845 (Australia)

    2015-06-28

    Radiation damage cascades in diamond are studied by molecular dynamics simulations employing the Environment Dependent Interaction Potential for carbon. Primary knock-on atom (PKA) energies up to 2.5 keV are considered and a uniformly distributed set of 25 initial PKA directions provide robust statistics. The simulations reveal the atomistic origins of radiation-resistance in diamond and provide a comprehensive computational analysis of cascade evolution and dynamics. As for the case of graphite, the atomic trajectories are found to have a fractal-like character, thermal spikes are absent and only isolated point defects are generated. Quantitative analysis shows that the instantaneous maximum kinetic energy decays exponentially with time, and that the timescale of the ballistic phase has a power-law dependence on PKA energy. Defect recombination is efficient and independent of PKA energy, with only 50% of displacements resulting in defects, superior to graphite where the same quantity is nearly 75%.

  9. Numerical simulation of long-term radiation effects for MOSFETs

    Wei Yuan; Xie Honggang; Gong Ding; Zhu Jinhui; Niu Shengli; Huang Liuxing

    2013-01-01

    A coupled algorithm is introduced to simulate the long-term radiation effects of MOSFETs, which combines particle transport with semiconductor governing equations. The former is dealt with Monte-Carlo method, and the latter is solved by finite-volume method. The trapped charge in SiO 2 and the free charge in Si are both described by the drift-diffusion model, and the deposited energy by incident particles can be coupled with the continuous equations of charge, acting as a source item. The discrete form of governing equations is obtained using the finite-volume method, and the numerical solutions of these equations are the long-term radiation response result of MOSFETs. The threshold voltage shift and off-state leakage current of an irradiated MOSFET are simulated with the coupled algorithm respectively, showing a good accordance with results by other calculations. (authors)

  10. Coherent Smith-Purcell radiation: Theories and simulations

    Donohue, J.T.; Gardelle, J.

    2008-01-01

    Smith-Purcell (SP) radiation has been observed many times over the past fifty years, and several theories have been proposed to explain it. However, it is only quite recently that Andrews, Brau and collaborators made a considerable advance in understanding how coherent SP radiation may be produced from an initially continuous beam. Their work received support from 2-D simulations which were performed using the Particle-in-Cell (PIC) code 'MAGIC'. Here we present a review of our 2-D simulations of coherent SP and discuss how they relate to the model of Andrews and Brau. We also describe briefly a SP experiment in the microwave domain using a sheet beam that is planned for 2008

  11. Radiation Simulations for the Proposed ISOL Stations for RIA

    Ronningen, Reginald; Beene, James R; Blideanu, Valetin; Boles, Jason; Bollen, Georg; Bredeweg, Todd; Bricault, Pierre; Burgess, Thomas; Carter, Ken; Conner, David L; Gabriel, Tony A; Heilbronn, Lawrence; Lawton, Don; Mansur, Louis; Mantica, Paul; Morrissey, David; Nortier, Francois M; Remec, Igor; Rennich, Mark; Reyes, Susana; Sherrill, Bradley; Stein, Werner; Stracener, Dan; Vieira, David; Wendel, Mark; Zeller, Al

    2005-01-01

    The Department of Energy's Office of Nuclear Physics, within the Office of Science (SC), has given high priority to consider and analyze design concepts for the target areas for the production of rare isotopes via the ISOL technique at the Rare-Isotope Accelerator (RIA) Facility. Key criteria are the maximum primary beam power of 400 kW, minimizing target change-out time, good radiological protection, flexibility with respect to implementing new target concepts, and the analysis and minimization of hazards associated with the operation of the facility. We will present examples of on-going work on simulations of radiation heating of targets, surrounding components and shielding, component activation, and levels of radiation dose, using the simulation codes MARS, MCNPX, and PHITS. These results are important to make decisions that may have a major impact on the layout, operational efficiency and cost of the facility, hazard analysis, shielding design, civil construction, component design, and material selection...

  12. Simulations of radiative shocks and jet formation in laboratory plasmas

    Velarde, P; Gonzalez, M; GarcIa-Fernandez, C; Oliva, E [Instituto de Fusion Nuclear, Universidad Politcnica de Madrid, Madrid (Spain) (Spain); Kasperczuk, A; Pisarczyk, T [Institute of Plasma Physics and Laser Microfusion, Warsaw (Poland) (Poland); Ullschmied, J [Institute of Plasma Physics AS CR, Prague (Czech Republic) (Czech Republic); Stehle, C [LERMA, Observatoire de Paris, Meudon (France) (France); Rus, B [Institute of Physics, PALS Center, Prague (Czech Republic) (Czech Republic); GarcIa-Senz, D; Bravo, E; Relano, A [Departament de Fisica i Enginyeria Nuclear. Universitat Politecnica de Catalunya. Barcelona (Spain) (Spain)], E-mail: velarde@din.upm.es

    2008-05-01

    We present the simulations of two relevant hydrodynamical problems related to astrophysical phenomena performed by three different codes. The numerical results from these codes will be compared in order to test both the numerical method implemented inside them and the influence of the physical phenomena simulated by the codes. Under some conditions laser produced plasmas could be scaled to the typical conditions prevailing in astrophysical plasmas. Therefore, such similarity allows to use existing laser facilities and numerical codes suitable to a laser plasma regime, for studying astrophysical proccesses. The codes are the radiation fluid dynamic 2D ARWEN code and the 3D HERACLES, and, without radiation energy transport, a Smoothed-Particle Hydrodynamics (SPH) code. These codes use different numerical techniques and have overlapping range of application, from laser produced plasmas to astrophysical plasmas. We also present the first laser experiments obtaining cumulative jets with a velocity higher than 100 km/s.

  13. WE-B-BRD-02: MR Simulation for Radiation Therapy

    Sheng, K. [Deparment of Radiation Oncology, University of California Los Angeles (United States)

    2015-06-15

    The use of MRI in radiation therapy is rapidly increasing. Applications vary from the MRI simulator, to the MRI fused with CT, and to the integrated MRI+RT system. Compared with the standard MRI QA, a broader scope of QA features has to be defined in order to maximize the benefits of using MRI in radiation therapy. These QA features include geometric fidelity, image registration, motion management, cross-system alignment, and hardware interference. Advanced MRI techniques require a specific type of QA, as they are being widely used in radiation therapy planning, dose calculations, post-implant dosimetry, and prognoses. A vigorous and adaptive QA program is crucial to defining the responsibility of the entire radiation therapy group and detecting deviations from the performance of high-quality treatment. As a drastic departure from CT simulation, MRI simulation requires changes in the work flow of treatment planning and image guidance. MRI guided radiotherapy platforms are being developed and commercialized to take the advantage of the advance in knowledge, technology and clinical experience. This symposium will from an educational perspective discuss the scope and specific issues related to MRI guided radiotherapy. Learning Objectives: Understand the difference between a standard and a radiotherapy-specific MRI QA program. Understand the effects of MRI artifacts (geometric distortion and motion) on radiotherapy. Understand advanced MRI techniques (ultrashort echo, fast MRI including dynamic MRI and 4DMRI, diffusion, perfusion, and MRS) and related QA. Understand the methods to prepare MRI for treatment planning (electron density assignment, multimodality image registration, segmentation and motion management). Current status of MRI guided treatment platforms. Dr. Jihong Wang has a research grant with Elekta-MRL project. Dr. Ke Sheng receives research grants from Varian Medical systems.

  14. Quantitative Simulation of QARBM Challenge Events During Radiation Belt Enhancements

    Li, W.; Ma, Q.; Thorne, R. M.; Bortnik, J.; Chu, X.

    2017-12-01

    Various physical processes are known to affect energetic electron dynamics in the Earth's radiation belts, but their quantitative effects at different times and locations in space need further investigation. This presentation focuses on discussing the quantitative roles of various physical processes that affect Earth's radiation belt electron dynamics during radiation belt enhancement challenge events (storm-time vs. non-storm-time) selected by the GEM Quantitative Assessment of Radiation Belt Modeling (QARBM) focus group. We construct realistic global distributions of whistler-mode chorus waves, adopt various versions of radial diffusion models (statistical and event-specific), and use the global evolution of other potentially important plasma waves including plasmaspheric hiss, magnetosonic waves, and electromagnetic ion cyclotron waves from all available multi-satellite measurements. These state-of-the-art wave properties and distributions on a global scale are used to calculate diffusion coefficients, that are then adopted as inputs to simulate the dynamical electron evolution using a 3D diffusion simulation during the storm-time and the non-storm-time acceleration events respectively. We explore the similarities and differences in the dominant physical processes that cause radiation belt electron dynamics during the storm-time and non-storm-time acceleration events. The quantitative role of each physical process is determined by comparing against the Van Allen Probes electron observations at different energies, pitch angles, and L-MLT regions. This quantitative comparison further indicates instances when quasilinear theory is sufficient to explain the observed electron dynamics or when nonlinear interaction is required to reproduce the energetic electron evolution observed by the Van Allen Probes.

  15. Accretion disc dynamo activity in local simulations spanning weak-to-strong net vertical magnetic flux regimes

    Salvesen, Greg; Simon, Jacob B.; Armitage, Philip J.; Begelman, Mitchell C.

    2016-03-01

    Strongly magnetized accretion discs around black holes have attractive features that may explain enigmatic aspects of X-ray binary behaviour. The structure and evolution of these discs are governed by a dynamo-like mechanism, which channels part of the accretion power liberated by the magnetorotational instability (MRI) into an ordered toroidal magnetic field. To study dynamo activity, we performed three-dimensional, stratified, isothermal, ideal magnetohydrodynamic shearing box simulations. The strength of the self-sustained toroidal magnetic field depends on the net vertical magnetic flux, which we vary across almost the entire range over which the MRI is linearly unstable. We quantify disc structure and dynamo properties as a function of the initial ratio of mid-plane gas pressure to vertical magnetic field pressure, β _0^mid = p_gas / p_B. For 10^5 ≥ β _0^mid ≥ 10 the effective α-viscosity parameter scales as a power law. Dynamo activity persists up to and including β _0^mid = 10^2, at which point the entire vertical column of the disc is magnetic pressure dominated. Still stronger fields result in a highly inhomogeneous disc structure, with large density fluctuations. We show that the turbulent steady state βmid in our simulations is well matched by the analytic model of Begelman et al. describing the creation and buoyant escape of toroidal field, while the vertical structure of the disc can be broadly reproduced using this model. Finally, we discuss the implications of our results for observed properties of X-ray binaries.

  16. Ion bombardment simulation: a review related to fusion radiation damage

    Brimhall, J.L.

    1975-01-01

    Prime emphasis is given to reviewing the ion bombardment data on the refractory metals molybdenum, niobium and vanadium which have been proposed for use in advanced fusion devices. The temperature and dose dependence of the void parameters are correlated among these metals. The effect of helium and hydrogen gas on the void parameters is also included. The similarities and differences of the response of these materials to high dose, high temperature radiation damage are evaluated. Comparisons are made with results obtained from stainless steel and nickel base alloys. The ion bombardment data is then compared and correlated, as far as possible, with existing neutron data on the refractory metals. The theoretically calculated damage state produced by neutrons and ions is also briefly discussed and compared to experimental data wherever possible. The advantages and limitations of ion simulation in relation to fusion radiation damage are finally summarized

  17. Coloured Petri Nets

    Jensen, Kurt

    1991-01-01

    This paper describes how Coloured Petri Nets (CP-nets) have been developed — from being a promising theoretical model to being a full-fledged language for the design, specification, simulation, validation and implementation of large software systems (and other systems in which human beings and...

  18. Radiation chemistry in the Jovian stratosphere - Laboratory simulations

    Mcdonald, Gene D.; Thompson, W. R.; Sagan, Carl

    1992-01-01

    The results of the present low-pressure/continuous-flow laboratory simulations of H2/He/CH4/NH3 atmospheres' plasma-induced chemistry indicate radiation yields of both hydrocarbon and N2-containing organic compounds which increase with decreasing pressure. On the basis of these findings, upper limits of 1 million-1 billion molecules/sq cm/sec are established for production rates of major auroral-chemistry species in the Jovian stratosphere. It is noted that auroral processes may account for 10-100 percent of the total abundances of most of the observed polar-region organic species.

  19. A Novel Radiation Transport Algorithm for Radiography Simulations

    Inanc, Feyzi

    2004-01-01

    The simulations used in the NDE community are becoming more realistic with the introduction of more physics. In this work, we have developed a new algorithm that is capable of representing photon and charged particle fluxes through spherical harmonic expansions in a manner similar to well known discrete ordinates method with the exception that Boltzmann operator is treated through exact integration rather than conventional Legendre expansions. This approach provides a mean to include radiation interactions for higher energy regimes where there are additional physical mechanisms for photons and charged particles

  20. Investigation of Radiation Protection Methodologies for Radiation Therapy Shielding Using Monte Carlo Simulation and Measurement

    Tanny, Sean

    The advent of high-energy linear accelerators for dedicated medical use in the 1950's by Henry Kaplan and the Stanford University physics department began a revolution in radiation oncology. Today, linear accelerators are the standard of care for modern radiation therapy and can generate high-energy beams that can produce tens of Gy per minute at isocenter. This creates a need for a large amount of shielding material to properly protect members of the public and hospital staff. Standardized vault designs and guidance on shielding properties of various materials are provided by the National Council on Radiation Protection (NCRP) Report 151. However, physicists are seeking ways to minimize the footprint and volume of shielding material needed which leads to the use of non-standard vault configurations and less-studied materials, such as high-density concrete. The University of Toledo Dana Cancer Center has utilized both of these methods to minimize the cost and spatial footprint of the requisite radiation shielding. To ensure a safe work environment, computer simulations were performed to verify the attenuation properties and shielding workloads produced by a variety of situations where standard recommendations and guidance documents were insufficient. This project studies two areas of concern that are not addressed by NCRP 151, the radiation shielding workload for the vault door with a non-standard design, and the attenuation properties of high-density concrete for both photon and neutron radiation. Simulations have been performed using a Monte-Carlo code produced by the Los Alamos National Lab (LANL), Monte Carlo Neutrons, Photons 5 (MCNP5). Measurements have been performed using a shielding test port designed into the maze of the Varian Edge treatment vault.

  1. Simulation and test of 3D silicon radiation detectors

    Fleta, C.; Pennicard, D.; Bates, R.; Parkes, C.; Pellegrini, G.; Lozano, M.; Wright, V.; Boscardin, M.; Dalla Betta, G.-F.; Piemonte, C.; Pozza, A.; Ronchin, S.; Zorzi, N.

    2007-01-01

    The work presented here is the result of the collaborative effort between the University of Glasgow, ITC-IRST (Trento) and IMB-CNM (Barcelona) in the framework of the CERN-RD50 Collaboration to produce 3D silicon radiation detectors and study their performance. This paper reports on two sets of 3D devices. IRST and CNM have fabricated a set of single-type column 3D detectors, which have columnar electrodes of the same doping type and an ohmic contact located at the backplane. Simulations of the device behaviour and electrical test results are presented. In particular, current-voltage, capacitance-voltage and charge collection efficiency measurements are reported. Other types of structures called double-sided 3D detectors are currently being fabricated at CNM. In these detectors the sets of n and p columns are made on opposite sides of the device. Electrical and technological simulations and first processing results are presented

  2. Relationship of in-coming radiation with photosynthetically active, infra-red and net radiations in Brassica species and rocket salad (Eruca sativa)

    Nandwal, A.S.; Kuhad, M.S.

    1989-01-01

    Marked variation was observed among genotypes when the data for in-coming solar radiation were monitored horizontally. The regression equation for in-coming solar radiation versus photosynthetically active radiation and incoming solar radiation versus in-coming infra red radiation indicated linear relationship

  3. Monte Carlo simulation of radiation streaming from a radioactive material shipping cask

    Liu, Y.Y.; Schwarz, R.A.; Tang, J.S.

    1996-01-01

    Simulated detection of gamma radiation streaming from a radioactive material shipping cask have been performed with the Monte Carlo codes MCNP4A and MORSE-SGC/S. Despite inherent difficulties in simulating deep penetration of radiation and streaming, the simulations have yielded results that agree within one order of magnitude with the radiation survey data, with reasonable statistics. These simulations have also provided insight into modeling radiation detection, notably on location and orientation of the radiation detector with respect to photon streaming paths, and on techniques used to reduce variance in the Monte Carlo calculations. 13 refs., 4 figs., 2 tabs

  4. Comparison of 37 months global net radiation flux derived from PICARD-BOS over the same period observations of CERES and ARGO

    Zhu, Ping; Wild, Martin

    2016-04-01

    The absolute level of the global net radiation flux (NRF) is fixed at the level of [0.5-1.0] Wm-2 based on the ocean heat content measurements [1]. The space derived global NRF is at the same order of magnitude than the ocean [2]. Considering the atmosphere has a negligible effects on the global NRF determination, the surface global NRF is consistent with the values determined from space [3]. Instead of studying the absolute level of the global NRF, we focus on the interannual variation of global net radiation flux, which were derived from the PICARD-BOS experiment and its comparison with values over the same period but obtained from the NASA-CERES system and inferred from the ocean heat content survey by ARGO network. [1] Allan, Richard P., Chunlei Liu, Norman G. Loeb, Matthew D. Palmer, Malcolm Roberts, Doug Smith, and Pier-Luigi Vidale (2014), Changes in global net radiative imbalance 1985-2012, Geophysical Research Letters, 41 (no.15), 5588-5597. [2] Loeb, Norman G., John M. Lyman, Gregory C. Johnson, Richard P. Allan, David R. Doelling, Takmeng Wong, Brian J. Soden, and Graeme L. Stephens (2012), Observed changes in top-of-the-atmosphere radiation and upper-ocean heating consistent within uncertainty, Nature Geoscience, 5 (no.2), 110-113. [3] Wild, Martin, Doris Folini, Maria Z. Hakuba, Christoph Schar, Sonia I. Seneviratne, Seiji Kato, David Rutan, Christof Ammann, Eric F. Wood, and Gert Konig-Langlo (2015), the energy balance over land and oceans: an assessment based on direct observations and CMIP5 climate models, Climate Dynamics, 44 (no.11-12), 3393-3429.

  5. A tunable integrated system to simulate colder stellar radiation

    Erculiani, Marco S.; Claudi, Riccardo; Barbisan, Diego; Giro, Enrico; Bonato, Matteo; Cocola, Lorenzo; Farisato, Giancarlo; Meneghini, Metteo; Poletto, Luca; Salasnich, Bernardo; Trivellin, Nicola

    2015-09-01

    In the last years, a lot of extrasolar planets have been discovered in any direction of the Galaxy. More interesting, some of them have been found in the habitable zone of their host stars. A large diversity of spectral type, from early types (A) to colder ones (M), is covered by the planetary system host stars. A lot of efforts are done in order to find habitable planets around M stars and indeed some habitable super earths were found. In this framework, "Atmosphere in a Test Tube", a project started at Astronomical observatory of Padua, simulates planetary environmental condition in order to understand how and how much the behavior of photosynthetic bacteria in different planetary/star scenarios can modify the planet atmosphere. The particular case of an habitable planet orbiting a M dwarf star is under study for the time being. The irradiation of an M star, due to its lower surface temperature is very different in quality and quantity by the irradiation of a star like our Sun. We would like to describe the study of feasibility of a new kind of tunable led stellarlight simulator capable to recreate the radiation spectrum of M type stars (but with the potential to be expanded even to F, G, K star spectra types) incident on the planet. The radiation source is a multiple LED matrix cooled by means of air fan technology. In order to endow it with modularity this device will be composed by a mosaic of circuit boards arranged in a pie-chart shape, on the surface of which will be welded the LEDs. This concept is a smart way in order to replace blown out pieces instead of changing the entire platform as well as implement the device with new modules suitable to reproduce other type of stars. The device can be driven by a PC to raise or lower the intensity of both each LED and the lamp, in order to simulate as close as possible a portion of the star spectrum. The wavelength intervals overlap the limits of photosynthetic pigment absorption range (280-850 nm), while the

  6. Petri Nets

    In a computer system, for example, typical discrete events ... This project brought out a series of influential reports on Petri net theory in the mid and late ... Technology became a leading centre for Petri net research and from then on, Petri nets ...

  7. ERO and PIC simulations of gross and net erosion of tungsten in the outer strike-point region of ASDEX Upgrade

    A. Hakola

    2017-08-01

    Full Text Available We have modelled net and gross erosion of W in low-density l-mode plasmas in the low-field side strike point region of ASDEX Upgrade by ERO and Particle-in-Cell (PIC simulations. The observed net-erosion peak at the strike point was mainly due to the light impurities present in the plasma while the noticeable net-deposition regions surrounding the erosion maximum could be attributed to the strong E ×B drift and the magnetic field bringing eroded particles from a distance of several meters towards the private flux region. Our results also imply that the role of cross-field diffusion is very small in the studied plasmas. The simulations indicate net/gross erosion ratio of 0.2–0.6, which is in line with the literature data and what was determined spectroscopically. The deviations from the estimates extracted from post-exposure ion-beam-analysis data (∼0.6–0.7 are most likely due to the measured re-deposition patterns showing the outcomes of multiple erosion-deposition cycles.

  8. Numerical simulation of radiation fog in complex terrain

    Zhang, X.; Musson-Genon, L.; Carissimo, B.; Dupont, E.

    2009-09-01

    The interest for micro-scale modeling of the atmosphere is growing for environmental applications related, for example, to energy production, transport and urban development. The turbulence in the stable layers where pollutant dispersion is low and can lead to strong pollution events. This could be further complicated by the presence of clouds or fog and is specifically difficult in urban or industrial area due to the presence of buildings. In this context, radiation fog formation and dissipation over complex terrain were therefore investigated with a state-of-the-art model. This study is divided into two phases. The first phase is a pilot stage, which consist of employing a database from the ParisFog campaign which took place in the south of Paris during winter 2006-07 to assess the ability of the cloud model to reproduce the detailed structure of radiation fog. The second phase use the validated model for the study of influence of complex terrain on fog evolution. Special attention is given to the detailed and complete simulations and validation technique used is to compare the simulated results using the 3D cloud model of computational fluid dynamical software Code_Saturne with one of the best collected in situ data during the ParisFog campaign. Several dynamical, microphysical parameterizations and simulation conditions have been described. The resulting 3D cloud model runs at a horizontal resolution of 30 m and a vertical resolution comparable to the 1D model. First results look very promising and are able to reproduce the spatial distribution of fog. The analysis of the behavior of the different parameterized physical processes suggests that the subtle balance between the various processes is achieved.

  9. Research on cloud background infrared radiation simulation based on fractal and statistical data

    Liu, Xingrun; Xu, Qingshan; Li, Xia; Wu, Kaifeng; Dong, Yanbing

    2018-02-01

    Cloud is an important natural phenomenon, and its radiation causes serious interference to infrared detector. Based on fractal and statistical data, a method is proposed to realize cloud background simulation, and cloud infrared radiation data field is assigned using satellite radiation data of cloud. A cloud infrared radiation simulation model is established using matlab, and it can generate cloud background infrared images for different cloud types (low cloud, middle cloud, and high cloud) in different months, bands and sensor zenith angles.

  10. Radiative forcing in the ACCMIP historical and future climate simulations

    D. T. Shindell

    2013-03-01

    Full Text Available The Atmospheric Chemistry and Climate Model Intercomparison Project (ACCMIP examined the short-lived drivers of climate change in current climate models. Here we evaluate the 10 ACCMIP models that included aerosols, 8 of which also participated in the Coupled Model Intercomparison Project phase 5 (CMIP5. The models reproduce present-day total aerosol optical depth (AOD relatively well, though many are biased low. Contributions from individual aerosol components are quite different, however, and most models underestimate east Asian AOD. The models capture most 1980–2000 AOD trends well, but underpredict increases over the Yellow/Eastern Sea. They strongly underestimate absorbing AOD in many regions. We examine both the direct radiative forcing (RF and the forcing including rapid adjustments (effective radiative forcing; ERF, including direct and indirect effects. The models' all-sky 1850 to 2000 global mean annual average total aerosol RF is (mean; range −0.26 W m−2; −0.06 to −0.49 W m−2. Screening based on model skill in capturing observed AOD yields a best estimate of −0.42 W m−2; −0.33 to −0.50 W m−2, including adjustment for missing aerosol components in some models. Many ACCMIP and CMIP5 models appear to produce substantially smaller aerosol RF than this best estimate. Climate feedbacks contribute substantially (35 to −58% to modeled historical aerosol RF. The 1850 to 2000 aerosol ERF is −1.17 W m−2; −0.71 to −1.44 W m−2. Thus adjustments, including clouds, typically cause greater forcing than direct RF. Despite this, the multi-model spread relative to the mean is typically the same for ERF as it is for RF, or even smaller, over areas with substantial forcing. The largest 1850 to 2000 negative aerosol RF and ERF values are over and near Europe, south and east Asia and North America. ERF, however, is positive over the Sahara, the Karakoram, high Southern latitudes and especially the Arctic. Global aerosol RF

  11. Radiative forcing in the ACCMIP historical and future climate simulations

    Shindell, D. T.; Lamarque, J. -F.; Schulz, M.; Flanner, M.; Jiao, C.; Chin, M.; Young, P. J.; Lee, Y. H.; Rotstayn, L.; Mahowald, N.; Milly, G.; Faluvegi, G.; Balkanski, Y.; Collins, W. J.; Conley, A. J.; Dalsoren, S.; Easter, R.; Ghan, S.; Horowitz, L.; Liu, X.; Myhre, G.; Nagashima, T.; Naik, V.; Rumbold, S. T.; Skeie, R.; Sudo, K.; Szopa, S.; Takemura, T.; Voulgarakis, A.; Yoon, J. -H.; Lo, F.

    2013-01-01

    The Atmospheric Chemistry and Climate Model Intercomparison Project (ACCMIP) examined the short-lived drivers of climate change in current climate models. Here we evaluate the 10 ACCMIP models that included aerosols, 8 of which also participated in the Coupled Model Intercomparison Project phase 5 (CMIP5). The models reproduce present-day total aerosol optical depth (AOD) relatively well, though many are biased low. Contributions from individual aerosol components are quite different, however, and most models underestimate east Asian AOD. The models capture most 1980-2000 AOD trends well, but underpredict increases over the Yellow/Eastern Sea. They strongly underestimate absorbing AOD in many regions. We examine both the direct radiative forcing (RF) and the forcing including rapid adjustments (effective radiative forcing; ERF, including direct and indirect effects). The models’ all-sky 1850 to 2000 global mean annual average total aerosol RF is (mean; range) -0.26Wm-2-2. Screening based on model skill in capturing observed AOD yields a best estimate of -0.42Wm-2-2-2-2

  12. Device Simulation of Monolithic Active Pixel Sensors: Radiation Damage Effects

    Fourches, N.T.

    2009-01-01

    Vertexing for the future International Linear Collider represents a challenging goal because of the high spatial resolution required with low material budget and high ionizing radiation tolerance. CMOS Monolithic Active Pixel Sensors (MAPS) represent a good potential solution for this purpose. Up to now many MAPS sensors have been developed. They are based on various architectures and manufactured in different processes. However, up so far, the sensor diode has not been the subject of extensive modelization and simulation. Published simulation studies of sensor-signal formation have been less numerous than measurements on real sensors. This is a cause for concern because such sensor is physically based on the partially depleted diode, in the vicinity of which the electric field collects the minority carriers generated by an incident MIP (minimum ionizing particle). Although the microscopic mechanisms are well known and modelled, the global physical mechanisms for signal formation are not very rigorously established. This is partly due to the presence of a predominant diffusion component in the charge transport. We present here simulations mainly based on the S-PISCES code, in which physical mechanisms affecting transport are taken into account. Diffusion, influence of residual carrier concentration due to the doping level in the sensitive volume, and more importantly charge trapping due to deep levels in the active (detecting) layer are studied together with geometric aspects. The effect of neutron irradiation is studied to assess the effects of deep traps. A comparison with available experimental data, obtained on processed MAPS before or after neutron irradiation will be introduced. Simulated reconstruction of the Minimum Ionizing Particle (MIP) point of impact in two dimensions is also investigated. For further steps, guidelines for process choices of next Monolithic Active Pixel Sensors are introduced. (authors)

  13. Dynamic Monte Carlo simulations of radiatively accelerated GRB fireballs

    Chhotray, Atul; Lazzati, Davide

    2018-05-01

    We present a novel Dynamic Monte Carlo code (DynaMo code) that self-consistently simulates the Compton-scattering-driven dynamic evolution of a plasma. We use the DynaMo code to investigate the time-dependent expansion and acceleration of dissipationless gamma-ray burst fireballs by varying their initial opacities and baryonic content. We study the opacity and energy density evolution of an initially optically thick, radiation-dominated fireball across its entire phase space - in particular during the Rph matter-dominated fireballs due to Thomson scattering. We quantify the new phases by providing analytical expressions of Lorentz factor evolution, which will be useful for deriving jet parameters.

  14. Radiation damage in amorphous solids - a computer simulation

    Chaki, T.K.; Li, J.C.M.

    1984-01-01

    It is known for crystalline materials that injection of high energy atoms introduces point defects. The nature of defects is not known for amorphous solids. So a molecular dynamic simulation of radiation damage in an amorphous metal was carried out. An amorphous structure of 685 atoms with periodic boundary conditions in all 3 dimensions was equilibrated first. Then one atom on the surface was given a high initial velocity so it was injected inward. Radial temperature distribution around the line of injection was calculated as a function of time. Void distribution and its evolution with time in the direction of injection was calculated by counting the atomic centers in thin slabs perpendicular to the line of injection. The swelling of the whole solid was calculated also. Some results are compared with experiments

  15. Software Design for Interactive Graphic Radiation Treatment Simulation Systems*

    Kalet, Ira J.; Sweeney, Christine; Jacky, Jonathan

    1990-01-01

    We examine issues in the design of interactive computer graphic simulation programs for radiation treatment planning (RTP), as well as expert system programs that automate parts of the RTP process, in light of ten years of experience at designing, building and using such programs. An experiment in object-oriented design using standard Pascal shows that while some advantage is gained from the design, it is still difficult to achieve modularity and to integrate expert system components. A new design based on the Common LISP Object System (CLOS) is described. This series of designs for RTP software shows that this application benefits in specific ways from object-oriented design methods and appropriate languages and tools.

  16. Efficient Radiation Simulation in Complex Geometries with Applications to Planetary Entry, Phase I

    National Aeronautics and Space Administration — NASA aerocapture missions require an accurate evaluation of radiative thermal transport in order to simulate the aerothermal environment around space vehicles....

  17. Delayed radiation necrosis of the brain simulating a brain tumor

    Ikeda, Hiroya; Kanai, Nobuhiro; Kamikawa, Kiyoo

    1976-01-01

    Two cases of delayed radiation necrosis of the brain are reported. Case 1 was a 50-year-old man who had right hemiparesis and disorientation 26 months after Linac irradiation (5,000 rad), preceded by an operation for right maxillar carcinoma. A left carotid angiogram demonstrated a left temporal mass lesion, extending to the frontal lobe. Case 2 was a 41-year-old man who had previously had an operation for right intraorbital plasmocytoma, followed by two Co irradiations (6,400 rad, and 5,000 rad). He had the signs and symptoms of intracranial hypertension 36 months after his last irradiation. A left carotid angiogram demonstrated a left temporal mass lesion. Both cases were treated by administration of steroid hormone (which alleviated the signs and symptoms) and by temporal lobectomy. Microscopic examinations showed necrosis of the brain tissues associated with hyaline degeneration of blood vessel walls and perivascular cell infiltration. The signs and symptoms of intracranial hypertension subsided postoperatively. Thirteen other cases the same as ours were collected from literature. They showed the signs and symptoms simulating a brain tumor (like a metastatic brain tumor) after irradiation to extracranial malignant tumors. Diagnosis of radiation necrosis was made by operation or autopsy. A follow-up for a long time is necessary, because the pathological changes in the brain may be progressive and extending in some cases, although decompressive operations for mass lesions give excellent results. (auth.)

  18. Simulation of cloud/radiation interaction using a second-order turbulence radiative-convective model

    Kao, C.Y.; Smith, W.S.

    1994-01-01

    Extended sheets of low-level stratus and stratocumulus clouds are a persistent feature over the eastern parts of the major ocean basins associated with the quasi-permanent subtropical high-pressure systems. These clouds exert a strong influence on climate through their high albedo, compared with the underlying surface, and their low altitude. The former leads to a reduction of the net shortwave flux entering the atmosphere, and the latter leads to an infrared loss in a way essentially the same as the cloud-free conditions. This paper is a modeling study with the current understanding of the important physical processes associated with a cloud-capped boundary layer. The numerical model is a high-resolution one-dimensional version of the second-order turbulence convective/radiative model developed at the Los Alamos National Laboratory. Future work includes sensitivity tests to ascertain the model validity as well as to systematically include all the possible ambient atmospheric and surface conditions. Detailed budget analyses are also useful in categorizing the cloud-capped boundary layers into a few classes

  19. Simulation of radiation damage in Fe and Fe-Cr

    Lagerstedt, Christina

    2005-11-01

    Steel is an important structural material in nuclear reactors used for example in pressure vessels and fast reactor cladding. In reactor environments it has been observed that ferritic steels are more resistant to swelling than the austenitic steels typically used. Much effort has been put into developing basic models of FeCr alloys which can serve as model alloys for describing ferritic steels. As a result, a number of interatomic potentials for Fe and FeCr alloys exist today. For the work in this thesis, basic material properties coming from experiments or ab initio calculations were used to fit interatomic potentials for Fe, Cr and FeCr implementing both the embedded atom method and the Finnis-Sinclair formalisms. The potentials were then validated by molecular dynamic calculations of material properties such as defect formation energies, migration energies and thermal expansion. Further studies of potential performance were carried out in simulations of radiation damage cascades and thermal aging. The influence of the interatomic potential on the primary defect state in materials under irradiation was analyzed in a study comparing results obtained using four different potentials. The objective of the study was to find correlations between potential properties and the primary damage state produced in simulations of displacement cascades. The defect evolution and clustering during different cascade stages were also investigated to try to gain a better understanding of these processes

  20. An evaluation of Arctic cloud and radiation processes during the SHEBA year: simulation results from eight Arctic regional climate models

    Wyser, K.; Willen, U. [Rossby Centre, SMHI, Norrkoeping (Sweden); Jones, C.G.; Du, P.; Girard, E.; Laprise, R. [Universite du Quebec a Montreal, Canadian Regional Climate Modelling and Diagnostics Network, Montreal (Canada); Cassano, J.; Serreze, M.; Shaw, M.J. [University of Colorado, Cooperative Institute for Research in Environmental Sciences and Department of Atmospheric and Oceanic Sciences, Boulder, CO (United States); Christensen, J.H. [Danish Meteorological Institute, Copenhagen (Denmark); Curry, J.A. [School of Earth and Atmospheric Sciences, Georgia Institute of Technology, Atlanta, GA (United States); Dethloff, K.; Rinke, A. [Alfred Wegener Institute for Polar and Marine Research, Research Unit, Potsdam (Germany); Haugen, J.-E.; Koeltzow, M. [Norwegian Meteorological Institute, Oslo (Norway); Jacob, D.; Pfeifer, S. [Max Planck Institute for Meteorology, Hamburg (Germany); Lynch, A. [Monash University, School of Geography and Environmental Science, Melbourne (Australia); Tjernstroem, M.; Zagar, M. [Stockholm University, Department of Meteorology, Stockholm (Sweden)

    2008-02-15

    Eight atmospheric regional climate models (RCMs) were run for the period September 1997 to October 1998 over the western Arctic Ocean. This period was coincident with the observational campaign of the Surface Heat Budget of the Arctic Ocean (SHEBA) project. The RCMs shared common domains, centred on the SHEBA observation camp, along with a common model horizontal resolution, but differed in their vertical structure and physical parameterizations. All RCMs used the same lateral and surface boundary conditions. Surface downwelling solar and terrestrial radiation, surface albedo, vertically integrated water vapour, liquid water path and cloud cover from each model are evaluated against the SHEBA observation data. Downwelling surface radiation, vertically integrated water vapour and liquid water path are reasonably well simulated at monthly and daily timescales in the model ensemble mean, but with considerable differences among individual models. Simulated surface albedos are relatively accurate in the winter season, but become increasingly inaccurate and variable in the melt season, thereby compromising the net surface radiation budget. Simulated cloud cover is more or less uncorrelated with observed values at the daily timescale. Even for monthly averages, many models do not reproduce the annual cycle correctly. The inter-model spread of simulated cloud-cover is very large, with no model appearing systematically superior. Analysis of the co-variability of terms controlling the surface radiation budget reveal some of the key processes requiring improved treatment in Arctic RCMs. Improvements in the parameterization of cloud amounts and surface albedo are most urgently needed to improve the overall performance of RCMs in the Arctic. (orig.)

  1. Net Neutrality

    Savin, Andrej

    2017-01-01

    Repealing “net neutrality” in the US will have no bearing on Internet freedom or security there or anywhere else.......Repealing “net neutrality” in the US will have no bearing on Internet freedom or security there or anywhere else....

  2. NET-2 Network Analysis Program

    Malmberg, A.F.

    1974-01-01

    The NET-2 Network Analysis Program is a general purpose digital computer program which solves the nonlinear time domain response and the linearized small signal frequency domain response of an arbitrary network of interconnected components. NET-2 is capable of handling a variety of components and has been applied to problems in several engineering fields, including electronic circuit design and analysis, missile flight simulation, control systems, heat flow, fluid flow, mechanical systems, structural dynamics, digital logic, communications network design, solid state device physics, fluidic systems, and nuclear vulnerability due to blast, thermal, gamma radiation, neutron damage, and EMP effects. Network components may be selected from a repertoire of built-in models or they may be constructed by the user through appropriate combinations of mathematical, empirical, and topological functions. Higher-level components may be defined by subnetworks composed of any combination of user-defined components and built-in models. The program provides a modeling capability to represent and intermix system components on many levels, e.g., from hole and electron spatial charge distributions in solid state devices through discrete and integrated electronic components to functional system blocks. NET-2 is capable of simultaneous computation in both the time and frequency domain, and has statistical and optimization capability. Network topology may be controlled as a function of the network solution. (U.S.)

  3. Simulation of transition radiation and electron identification ability of the ATLAS TRT

    Klinkby, Esben Bryndt

    2013-01-01

    The Transition Radiation Tracker (TRT) is the outer most tracking detector of the ATLAS experiment. In addition as functioning as atracking detector, it is capable of providing particle identification information through the emission and subsequent absorption and detection of transition radiation....... Below the effort of simulating transition radiation production and detector response is discussed, with emphasis on the data/simulation agreement and tuning. © 2012 CERN. Published by Elsevier B.V. All rights reserved....

  4. Simulation of thermal radiation, illustrated by the Bridgman casting process for directional solidification of turbine blades; Simulation von Waermestrahlung am Beispiel des Bridgman-Verfahrens zur gerichteten Erstarrung von Turbinenschaufeln

    Hofmann, N

    1996-12-31

    Directionally solidified turbine blades for high-temperature applications today are commonly produced by the Bridgman casting process. The production of a newly constructed turbine blade requires a number of costly and time-consuming casting experiments. The author develops a numerical simulation model based on the finite element method and net radiation method for low-cost and short-term simulation and optimisation of the casting experiments. Several different numerical methods for calculating thermal radiation are compared (radiosity, ray tracing and the finite difference method), and the simulation results are presented for several exemplry turbine blades. Further, an optimisation strategy for improving the quality of the turbine blade casting process is presented. (orig.). 65 figs., 8 tabs. [Deutsch] Gerichtet erstarrte Turbinenschaufeln mit hoher Einsatztemperatur werden nach dem heutigen Stand der Technik nach dem Bridgman-Verfahren gegossen. Die Herstellung einer neu konstruierten Turbinenschaufel verlangt eine Reihe von kosten- und zeitaufwendigen Giessexperimenten. In der vorliegenden Arbeit wird ein numerisches Simulationsmodell auf Basis der Finiten Elemente Methode und Net Radiation Methode entwickelt, mit dem sich kostenguenstig und in kurzen Zeitraeumen die Giessversuche simulieren und optimieren lassen. Die Arbeit vergleicht verschiedene numerische Loesungsverfahren fuer die Waermestrahlung (Radiosity, Ray Tracing und Finite Differenzen Verfahren) und stellt am Beispiel einiger Turbinenschaufeln die Simulationsergebnisse dar. Weiterhin wird eine Optimierungsstrategie fuer Verbesserung der Gussqualitaet von Turbinenschaufeln vorgestellt. (orig.)

  5. Atomistic simulations of the radiation resistance of oxides

    Chartier, A.; Van Brutzel, L.; Crocombette, J.-P.

    2012-01-01

    Fluorite compounds such as urania and ceria, or related compounds such as pyrochlores and also spinels show different behaviors under irradiations, which ranges from perfect radiation resistance to crystalline phase change or even complete amorphization depending on their structure and/or their composition. Displacement cascades – dedicated to the understanding of the ballistic regime and performed by empirical potentials molecular dynamics simulations – have revealed that the remaining damages of the above mentioned oxides are reduced to point defects unlike what is observed in zircon and zirconolite, which directly amorphize during the cascade. The variable behavior of these point defects is the key of the various responses of these materials to irradiations. This behavior can be investigated by two specific molecular dynamics methodologies that will be reviewed here: (i) the method of point defects accumulation as a function of temperature that gives access to the dose effects and to the critical doses for amorphization; (ii) the study Frenkel pairs life-time – i.e. their time of recombination as function of temperature – that may be used as a tool to understand the results obtained in displacements cascades or to identify the microscopic mechanisms responsible for the amorphization/re-crystallization during the point defects accumulations.

  6. Fast simulation tool for ultraviolet radiation at the earth's surface

    Engelsen, Ola; Kylling, Arve

    2005-04-01

    FastRT is a fast, yet accurate, UV simulation tool that computes downward surface UV doses, UV indices, and irradiances in the spectral range 290 to 400 nm with a resolution as small as 0.05 nm. It computes a full UV spectrum within a few milliseconds on a standard PC, and enables the user to convolve the spectrum with user-defined and built-in spectral response functions including the International Commission on Illumination (CIE) erythemal response function used for UV index calculations. The program accounts for the main radiative input parameters, i.e., instrumental characteristics, solar zenith angle, ozone column, aerosol loading, clouds, surface albedo, and surface altitude. FastRT is based on look-up tables of carefully selected entries of atmospheric transmittances and spherical albedos, and exploits the smoothness of these quantities with respect to atmospheric, surface, geometrical, and spectral parameters. An interactive site, http://nadir.nilu.no/~olaeng/fastrt/fastrt.html, enables the public to run the FastRT program with most input options. This page also contains updated information about FastRT and links to freely downloadable source codes and binaries.

  7. Sunspot Modeling: From Simplified Models to Radiative MHD Simulations

    Rolf Schlichenmaier

    2011-09-01

    Full Text Available We review our current understanding of sunspots from the scales of their fine structure to their large scale (global structure including the processes of their formation and decay. Recently, sunspot models have undergone a dramatic change. In the past, several aspects of sunspot structure have been addressed by static MHD models with parametrized energy transport. Models of sunspot fine structure have been relying heavily on strong assumptions about flow and field geometry (e.g., flux-tubes, "gaps", convective rolls, which were motivated in part by the observed filamentary structure of penumbrae or the necessity of explaining the substantial energy transport required to maintain the penumbral brightness. However, none of these models could self-consistently explain all aspects of penumbral structure (energy transport, filamentation, Evershed flow. In recent years, 3D radiative MHD simulations have been advanced dramatically to the point at which models of complete sunspots with sufficient resolution to capture sunspot fine structure are feasible. Here overturning convection is the central element responsible for energy transport, filamentation leading to fine-structure and the driving of strong outflows. On the larger scale these models are also in the progress of addressing the subsurface structure of sunspots as well as sunspot formation. With this shift in modeling capabilities and the recent advances in high resolution observations, the future research will be guided by comparing observation and theory.

  8. Simulation of solar radiative transfer in cumulus clouds

    Zuev, V.E.; Titov, G.A. [Institute of Atmospheric Optics, Tomsk (Russian Federation)

    1996-04-01

    This work presents a 3-D model of radiative transfer which is used to study the relationship between the spatial distribution of cumulus clouds and fluxes (albedo and transmittance) of visible solar radiation.

  9. A hybrid Genetic Algorithm and Monte Carlo simulation approach to predict hourly energy consumption and generation by a cluster of Net Zero Energy Buildings

    Garshasbi, Samira; Kurnitski, Jarek; Mohammadi, Yousef

    2016-01-01

    Graphical abstract: The energy consumption and renewable generation in a cluster of NZEBs are modeled by a novel hybrid Genetic Algorithm and Monte Carlo simulation approach and used for the prediction of instantaneous and cumulative net energy balances and hourly amount of energy taken from and supplied to the central energy grid. - Highlights: • Hourly energy consumption and generation by a cluster of NZEBs was simulated. • Genetic Algorithm and Monte Carlo simulation approach were employed. • Dampening effect of energy used by a cluster of buildings was demonstrated. • Hourly amount of energy taken from and supplied to the grid was simulated. • Results showed that NZEB cluster was 63.5% grid dependant on annual bases. - Abstract: Employing a hybrid Genetic Algorithm (GA) and Monte Carlo (MC) simulation approach, energy consumption and renewable energy generation in a cluster of Net Zero Energy Buildings (NZEBs) was thoroughly investigated with hourly simulation. Moreover, the cumulative energy consumption and generation of the whole cluster and each individual building within the simulation space were accurately monitored and reported. The results indicate that the developed simulation algorithm is able to predict the total instantaneous and cumulative amount of energy taken from and supplied to the central energy grid over any time period. During the course of simulation, about 60–100% of total daily generated renewable energy was consumed by NZEBs and up to 40% of that was fed back into the central energy grid as surplus energy. The minimum grid dependency of the cluster was observed in June and July where 11.2% and 9.9% of the required electricity was supplied from the central energy grid, respectively. On the other hand, the NZEB cluster was strongly grid dependant in January and December by importing 70.7% and 76.1% of its required energy demand via the central energy grid, in the order given. Simulation results revealed that the cluster was 63

  10. Radiation effects in vitreous and devitrified simulated waste glass

    Weber, W.J.; Turcotte, R.P.; Bunnell, L.R.; Roberts, F.P.; Westsik, J.H. Jr.

    1979-01-01

    The long-term radiation stability of vitreous and partially devitrified forms of high-level waste glass was investigated in accelerated experiments by 266 Cm doping. The effects of radiation on microstructure, phase behavior, density, impact strength, stored energy, and leachability are reported to a cumulative radiation dose of 5 x 10 18 α decays/cm 3 . This dose produces saturation of radiation effects in most properties. 4 figures

  11. Diurnal changes of net photosynthetic rate (NPR) in leaves of Lonicera japonica Thunb. and the responding mathematical model of NPR to photosynthetic valid radiation

    Wu Dafu; Zhang Shengli; Li Dongfang

    2009-01-01

    [Objective] The study provided theoretical basis for production practice . [Method] With Lonicera japonica Thunb .as material, diurnal changes of net photosynthetic rate (NPR) in leaves of the plant and the responding mathematical model of NPR to photosynthetic valid radiation were studied using portable photosynthetic determinator system. [Result] Like most of C3 plants, the diurnal changes curve of NPR of Lonicera japonica Thunb .showed double peaks, but there were time difference in reaching the peak value between the study and previous ones . The responding mathematical model of NPR to photosynthetic valid radiation could be described by three mathematic functions, such as logarithm, linearity and binomial, but binomial function was more precise than the others. Light saturation point of Lonicera japonica Thunb. was figured out by binomial equation deduced in the study , and light saturation point was 1 086 .3 μmol/ (m2•s) . [Conclusion] The diurnal changes curve of NPR of Lonicera japonica Thunb .showed double peaks, and the responding mathematical model of NPR to photosynthetic valid radiation could be described by binomial functions

  12. Petri Nets

    GENERAL I ARTICLE ... In Part 1 of this two-part article, we have seen im- ..... mable logic controller and VLSI arrays, office automation systems, workflow management systems, ... complex discrete event and real-time systems; and Petri nets.

  13. Dermatopathology effects of simulated solar particle event radiation exposure in the porcine model.

    Sanzari, Jenine K; Diffenderfer, Eric S; Hagan, Sarah; Billings, Paul C; Gridley, Daila S; Seykora, John T; Kennedy, Ann R; Cengel, Keith A

    2015-07-01

    The space environment exposes astronauts to risks of acute and chronic exposure to ionizing radiation. Of particular concern is possible exposure to ionizing radiation from a solar particle event (SPE). During an SPE, magnetic disturbances in specific regions of the Sun result in the release of intense bursts of ionizing radiation, primarily consisting of protons that have a highly variable energy spectrum. Thus, SPE events can lead to significant total body radiation exposures to astronauts in space vehicles and especially while performing extravehicular activities. Simulated energy profiles suggest that SPE radiation exposures are likely to be highest in the skin. In the current report, we have used our established miniature pig model system to evaluate the skin toxicity of simulated SPE radiation exposures that closely resemble the energy and fluence profile of the September, 1989 SPE using either conventional radiation (electrons) or proton simulated SPE radiation. Exposure of animals to electron or proton radiation led to dose-dependent increases in epidermal pigmentation, the presence of necrotic keratinocytes at the dermal-epidermal boundary and pigment incontinence, manifested by the presence of melanophages in the derm is upon histological examination. We also observed epidermal hyperplasia and a reduction in vascular density at 30 days following exposure to electron or proton simulated SPE radiation. These results suggest that the doses of electron or proton simulated SPE radiation results in significant skin toxicity that is quantitatively and qualitatively similar. Radiation-induced skin damage is often one of the first clinical signs of both acute and non-acute radiation injury where infection may occur, if not treated. In this report, histopathology analyses of acute radiation-induced skin injury are discussed. Copyright © 2015 The Committee on Space Research (COSPAR). Published by Elsevier Ltd. All rights reserved.

  14. Radiative Forcing in the ACCMIP Historical and Future Climate Simulations

    Shindell, Drew Todd; Lamarque, J.-F.; Schulz, M.; Flanner, M.; Jiao, C.; Chin, M.; Young, P. J.; Lee, Y. H.; Rotstayn, L.; Mahowald, N.; hide

    2013-01-01

    A primary goal of the Atmospheric Chemistry and Climate Model IntercomparisonProject (ACCMIP) was to characterize the short-lived drivers of preindustrial to 2100climate change in the current generation of climate models. Here we evaluate historicaland 5 future radiative forcing in the 10 ACCMIP models that included aerosols, 8 of whichalso participated in the Coupled Model Intercomparison Project phase 5 (CMIP5).The models generally reproduce present-day climatological total aerosol opticaldepth (AOD) relatively well. components to this total, however, and most appear to underestimate AOD over East10 Asia. The models generally capture 1980-2000 AOD trends fairly well, though theyunderpredict AOD increases over the YellowEastern Sea. They appear to strongly underestimate absorbing AOD, especially in East Asia, South and Southeast Asia, SouthAmerica and Southern Hemisphere Africa.We examined both the conventional direct radiative forcing at the tropopause (RF) and the forcing including rapid adjustments (adjusted forcing AF, including direct andindirect effects). The models calculated all aerosol all-sky 1850 to 2000 global meanannual average RF ranges from 0.06 to 0.49 W m(sup -2), with a mean of 0.26 W m(sup -2) and a median of 0.27 W m(sup -2. Adjusting for missing aerosol components in some modelsbrings the range to 0.12 to 0.62W m(sup -2), with a mean of 0.39W m(sup -2). Screen20ing the models based on their ability to capture spatial patterns and magnitudes ofAOD and AOD trends yields a quality-controlled mean of 0.42W m(sup -2) and range of0.33 to 0.50 W m(sup -2) (accounting for missing components). The CMIP5 subset of ACCMIPmodels spans 0.06 to 0.49W m(sup -2), suggesting some CMIP5 simulations likelyhave too little aerosol RF. A substantial, but not well quantified, contribution to histori25cal aerosol RF may come from climate feedbacks (35 to 58). The mean aerosol AF during this period is 1.12W m(sup -2) (median value 1.16W m(sup -2), range 0.72 to1.44W m

  15. Cobalt-60 simulation of LOCA [loss of coolant accident] radiation effects

    Buckalew, W.H.

    1989-07-01

    The consequences of simulating nuclear reactor loss of coolant accident (LOCA) radiation effects with Cobalt-60 gamma ray irradiators have been investigated. Based on radiation induced damage in polymer base materials, it was demonstrated that electron/photon induced radiation damage could be related on the basis of average absorbed radiation dose. This result was used to estimate the relative effectiveness of the mixed beta/gamma LOCA and Cobalt-60 radiation environments to damage both bare and jacketed polymer base electrical insulation materials. From the results obtained, it is concluded that present simulation techniques are a conservative method for simulating LOCA radiation effects and that the practices have probably substantially overstressed both bare and jacketed materials during qualification testing. 9 refs., 8 figs., 5 tabs

  16. Simulation-based education: A narrative review of the use of VERT in radiation therapy education.

    Kane, Paul

    2018-04-14

    Simulation has a long history in medical and health science training and education. The literature describing this history is extensive. The role simulation plays in many health disciplines has evolved, as has the focus of the literature around it. The Virtual Environment for Radiotherapy Training (VERT) system is a relative newcomer to radiation therapy education and, similar to the literature around radiation therapy (RT) education, is still in its infancy. This narrative review sets the scene of simulation-based education within the health sciences and considers the lessons learned from published work on VERT to date. The evidence suggests that future inquiry involving VERT should explore different ways in which VERT can be used to contribute to the skillset required by the radiation therapist of tomorrow. © 2018 The Authors. Journal of Medical Radiation Sciences published by John Wiley & Sons Australia, Ltd on behalf of Australian Society of Medical Imaging and Radiation Therapy and New Zealand Institute of Medical Radiation Technology.

  17. Estimation of the soil heat flux/net radiation ratio based on spectral vegetation indexes in high-latitude Arctic areas

    Jacobsen, A.; Hansen, B.U.

    1999-01-01

    The vegetation communities in the Arctic environment are very sensitive to even minor climatic variations and therefore the estimation of surface energy fluxes from high-latitude vegetated areas is an important subject to be pursued. This study was carried out in July-August and used micro meteorological data, spectral reflectance signatures, and vegetation biomass to establish the relation between the soil heat flux/net radiation (G / Rn) ratio and spectral vegetation indices (SVIs). Continuous measurements of soil temperature and soil heat flux were used to calculate the surface ground heat flux by use of conventional methods, and the relation to surface temperature was investigated. Twenty-seven locations were established, and six samples per location, including the measurement of the surface temperature and net radiation to establish the G/Rn ratio and simultaneous spectral reflectance signatures and wet biomass estimates, were registered. To obtain regional reliability, the locations were chosen in order to represent the different Arctic vegetation communities in the study area; ranging from dry tundra vegetation communities (fell fields and dry dwarf scrubs) to moist/wet tundra vegetation communities (snowbeds, grasslands and fens). Spectral vegetation indices, including the simple ratio vegetation index (RVI) and the normalized difference vegetation index (NDVI), were calculated. A comparison of SVIs to biomass proved that RVI gave the best linear expression, and NDVI the best exponential expression. A comparison of SVIs and the surface energy flux ratio G / Rn proved that NDVI gave the best linear expression. SPOT HRV images from July 1989 and 1992 were used to map NDVI and G / Rn at a regional scale. (author)

  18. The effect of early radiation in N-body simulations of cosmic structure formation

    Adamek, Julian; Brandbyge, Jacob; Fidler, Christian

    2017-01-01

    Newtonian N-body simulations have been employed successfully over the past decades for the simulation of the cosmological large-scale structure. Such simulations usually ignore radiation perturbations (photons and massless neutrinos) and the impact of general relativity (GR) beyond the background...

  19. RADIATIVE MODELS OF SGR A* FROM GRMHD SIMULATIONS

    Moscibrodzka, Monika; Gammie, Charles F.; Dolence, Joshua C.; Shiokawa, Hotaka; Leung, Po Kin

    2009-01-01

    Using flow models based on axisymmetric general relativistic magnetohydrodynamics simulations, we construct radiative models for Sgr A*. Spectral energy distributions (SEDs) that include the effects of thermal synchrotron emission and absorption, and Compton scattering, are calculated using a Monte Carlo technique. Images are calculated using a ray-tracing scheme. All models are scaled so that the 230 GHz flux density is 3.4 Jy. The key model parameters are the dimensionless black hole spin a * , the inclination i, and the ion-to-electron temperature ratio T i /T e . We find that (1) models with T i /T e = 1 are inconsistent with the observed submillimeter spectral slope; (2) the X-ray flux is a strongly increasing function of a * ; (3) the X-ray flux is a strongly increasing function of i; (4) 230 GHz image size is a complicated function of i, a * , and T i /T e , but the T i /T e = 10 models are generally large and at most marginally consistent with the 230 GHz very long baseline interferometry (VLBI) data; (5) for models with T i /T e = 10 and i = 85 deg. the event horizon is cloaked behind a synchrotron photosphere at 230 GHz and will not be seen by VLBI, but these models overproduce near-infrared and X-ray flux; (6) in all models whose SEDs are consistent with observations, the event horizon is uncloaked at 230 GHz; (7) the models that are most consistent with the observations have a * ∼ 0.9. We finish with a discussion of the limitations of our model and prospects for future improvements.

  20. General Relativistic Radiation MHD Simulations of Supercritical Accretion onto a Magnetized Neutron Star: Modeling of Ultraluminous X-Ray Pulsars

    Takahashi, Hiroyuki R. [Center for Computational Astrophysics, National Astronomical Observatory of Japan, National Institutes of Natural Sciences, Mitaka, Tokyo 181-8588 (Japan); Ohsuga, Ken, E-mail: takahashi@cfca.jp, E-mail: ken.ohsuga@nao.ac.jp [Division of Theoretical Astronomy, National Astronomical Observatory of Japan, National Institutes of Natural Sciences, Mitaka, Tokyo 181-8588 (Japan)

    2017-08-10

    By performing 2.5-dimensional general relativistic radiation magnetohydrodynamic simulations, we demonstrate supercritical accretion onto a non-rotating, magnetized neutron star, where the magnetic field strength of dipole fields is 10{sup 10} G on the star surface. We found the supercritical accretion flow consists of two parts: the accretion columns and the truncated accretion disk. The supercritical accretion disk, which appears far from the neutron star, is truncated at around ≃3 R {sub *} ( R {sub *} = 10{sup 6} cm is the neutron star radius), where the magnetic pressure via the dipole magnetic fields balances with the radiation pressure of the disks. The angular momentum of the disk around the truncation radius is effectively transported inward through magnetic torque by dipole fields, inducing the spin up of a neutron star. The evaluated spin-up rate, ∼−10{sup −11} s s{sup −1}, is consistent with the recent observations of the ultraluminous X-ray pulsars. Within the truncation radius, the gas falls onto a neutron star along the dipole fields, which results in a formation of accretion columns onto the northern and southern hemispheres. The net accretion rate and the luminosity of the column are ≃66 L {sub Edd}/ c {sup 2} and ≲10 L {sub Edd}, where L {sub Edd} is the Eddington luminosity and c is the light speed. Our simulations support a hypothesis whereby the ultraluminous X-ray pulsars are powered by the supercritical accretion onto the magnetized neutron stars.

  1. Mathematical simulation of gamma-radiation angle distribution measurements

    Batij, V.G.; Batij, E.V.; Egorov, V.V.; Fedorchenko, D.V.; Kochnev, N.A.

    2008-01-01

    We developed mathematical model of the facility for gamma-radiation angle distribution measurement and calculated response functions for gamma-radiation intensities. We developed special software for experimental data processing, the 'Shelter' object radiation spectra unfolding and Sphere detector (ShD) angle resolution estimation. Neuronet method using for detection of the radiation directions is given. We developed software based on the neuronet algorithm, that allows obtaining reliable distribution of gamma-sources that make impact on the facility detectors at the measurement point. 10 refs.; 15 figs.; 4 tab

  2. Step-by-Step Simulation of Radiation of Radiation Chemistry Using Green Functions for Diffusion-Influenced Reactions

    Plante, Ianik; Cucinotta, Francis A.

    2011-01-01

    The irradiation of biological systems leads to the formation of radiolytic species such as H(raised dot), (raised dot)OH, H2, H2O2, e(sup -)(sub aq), etc.[1]. These species react with neighboring molecules, which result in damage in biological molecules such as DNA. Radiation chemistry is there for every important to understand the radiobiological consequences of radiation[2]. In this work, we discuss an approach based on the exact Green Functions for diffusion-influenced reactions which may be used to simulate radiation chemistry and eventually extended to study more complex systems, including DNA.

  3. Comparative proteomic analysis of rice after seed ground simulated radiation and spaceflight explains the radiation effects of space environment

    Wang, Wei; Shi, Jinming; Liang, Shujian; Lei, Huang; Shenyi, Zhang; Sun, Yeqing

    In previous work, we compared the proteomic profiles of rice plants growing after seed space-flights with ground controls by two-dimensional difference gel electrophoresis (2-D DIGE) and found that the protein expression profiles were changed after seed space environment exposures. Spaceflight represents a complex environmental condition in which several interacting factors such as cosmic radiation, microgravity and space magnetic fields are involved. Rice seed is in the process of dormant of plant development, showing high resistance against stresses, so the highly ionizing radiation (HZE) in space is considered as main factor causing biological effects to seeds. To further investigate the radiation effects of space environment, we performed on-ground simulated HZE particle radiation and compared between the proteomes of seed irra-diated plants and seed spaceflight (20th recoverable satellite) plants from the same rice variety. Space ionization shows low-dose but high energy particle effects, for searching the particle effects, ground radiations with the same low-dose (2mGy) but different liner energy transfer (LET) values (13.3KeV/µm-C, 30KeV/µm-C, 31KeV/µm-Ne, 62.2KeV/µm-C, 500Kev/µm-Fe) were performed; using 2-D DIGE coupled with clustering and principle component analysis (PCA) for data process and comparison, we found that the holistic protein expression patterns of plants irradiated by LET-62.2KeV/µm carbon particles were most similar to spaceflight. In addition, although space environment presents a low-dose radiation (0.177 mGy/day on the satellite), the equivalent simulated radiation dose effects should still be evaluated: radiations of LET-62.2KeV/µm carbon particles with different cumulative doses (2mGy, 20mGy, 200mGy, 2000mGy) were further carried out and resulted that the 2mGy radiation still shared most similar proteomic profiles with spaceflight, confirming the low-dose effects of space radiation. Therefore, in the protein expression level

  4. RESTful NET

    Flanders, Jon

    2008-01-01

    RESTful .NET is the first book that teaches Windows developers to build RESTful web services using the latest Microsoft tools. Written by Windows Communication Foundation (WFC) expert Jon Flanders, this hands-on tutorial demonstrates how you can use WCF and other components of the .NET 3.5 Framework to build, deploy and use REST-based web services in a variety of application scenarios. RESTful architecture offers a simpler approach to building web services than SOAP, SOA, and the cumbersome WS- stack. And WCF has proven to be a flexible technology for building distributed systems not necessa

  5. Evapotranspiration estimates and consequences due to errors in the determination of the net radiation and advective effects

    Oliveira, G.M. de; Leitao, M. de M.V.B.R.

    2000-01-01

    The objective of this study was to analyze the consequences in the evapotranspiration estimates (ET) during the growing cycle of a peanut crop due to the errors committed in the determination of the radiation balance (Rn), as well as those caused by the advective effects. This research was conducted at the Experimental Station of CODEVASF in an irrigated perimeter located in the city of Rodelas, BA, during the period of September to December of 1996. The results showed that errors of the order of 2.2 MJ m -2 d -1 in the calculation of Rn, and consequently in the estimate of ET, can occur depending on the time considered for the daily total of Rn. It was verified that the surrounding areas of the experimental field, as well as the areas of exposed soil within the field, contributed significantly to the generation of local advection of sensible heat, which resulted in the increase of the evapotranspiration [pt

  6. Treatment of compounds and alloys in radiation hydrodynamics simulations of ablative laser loading

    Swift, Damian C.; Gammel, J. Tinka; Clegg, Samuel M.

    2004-01-01

    Different methods were compared for constructing models of the behavior of a prototype intermetallic compound, nickel aluminide, for use in radiation hydrodynamics simulations of shock wave generation by ablation induced by laser energy. The models included the equation of state, ionization, and radiation opacity. The methods of construction were evaluated by comparing the results of simulations of an ablatively generated shock wave in a sample of the alloy. The most accurate simulations were obtained using the 'constant number density' mixture model to calculate the equation of state and opacity, and Thomas-Fermi ionization. This model is consistent with that found to be most accurate for simulations of ablatively shocked elements

  7. Use of high voltage electron microscope to simulate radiation damage by neutrons

    Mayer, R.M.

    1976-01-01

    The use of the high voltage electron microscope to simulate radiation damage by neutrons is briefly reviewed. This information is important in explaining how alloying affects void formation during neutron irradiation

  8. Constructive and critical approach of the radiation damage simulation

    Becquart, Ch.

    2002-11-01

    This work deals with the problem of radiation damage in materials for applications in development of fission and nuclear fusion technologies. It is organised in 3 sections. In section 1 are presented the mechanisms of formation and the evolution kinetics of the primary damage. Section 2 is devoted to the study of the sensitivity of the radiation damage at different approximations. Section 3 discusses the contribution of the ab initio calculations to the study of radiation damage and more particularly the point defects in a dilute Fe-Cu ferritic alloy. This work is illustrated by several publications added in each section. (O.M.)

  9. Petri Nets

    Home; Journals; Resonance – Journal of Science Education; Volume 4; Issue 9. Petri Nets - Applications. Y Narahari. General Article Volume 4 Issue 9 September 1999 pp 44-52 ... Author Affiliations. Y Narahari1. Department of Computer Science and Automation, Indian Institute of Science, Bangalore 560 012, India.

  10. Net Gain

    Describing the effect of tax incentives for import, production, and sale of nets and insecticides; and ..... So far, China is the only country where a system for the routine treatment of ...... 1993), and the trials in Ecuador and Peru (Kroeger et al.

  11. The Simulation of the Recharging Method Based on Solar Radiation for an Implantable Biosensor.

    Li, Yun; Song, Yong; Kong, Xianyue; Li, Maoyuan; Zhao, Yufei; Hao, Qun; Gao, Tianxin

    2016-09-10

    A method of recharging implantable biosensors based on solar radiation is proposed. Firstly, the models of the proposed method are developed. Secondly, the recharging processes based on solar radiation are simulated using Monte Carlo (MC) method and the energy distributions of sunlight within the different layers of human skin have been achieved and discussed. Finally, the simulation results are verified experimentally, which indicates that the proposed method will contribute to achieve a low-cost, convenient and safe method for recharging implantable biosensors.

  12. New technique for global solar radiation forecasting by simulated annealing and genetic algorithms using

    Tolabi, H.B.; Ayob, S.M.

    2014-01-01

    In this paper, a novel approach based on simulated annealing algorithm as a meta-heuristic method is implemented in MATLAB software to estimate the monthly average daily global solar radiation on a horizontal surface for six different climate cities of Iran. A search method based on genetic algorithm is applied to accelerate problem solving. Results show that simulated annealing based on genetic algorithm search is a suitable method to find the global solar radiation. (author)

  13. State of Theory and Computer Simulations of Radiation Effects in Ceramics

    Corrales, Louis R.; Weber, William J.

    2003-01-01

    This article presents opinions based on the presentations and discussions at a Workshop on Theory and Computer Simulations of Radiation Effects in Ceramics held in August 2002 at Pacific Northwest National Laboratory in Richland, WA, USA. The workshop was focused on the current state-of-the-art of theory, modeling and simulation of radiation effects in oxide ceramics, directions for future breakthroughs, and creating a close integration with experiment

  14. GeoSteamNet: A computer code to simulate geothermal steam flow in a pipeline network; GeoSteamNet: Programa de computo para simular el flujo de vapor geotermico de una red de vaporductos

    Verma P., Mahendra; Aragon A., Alfonso [Instituto de Investigaciones Electricas, Cuernavaca, Morelos (Mexico)]. E-mail: mahendra@iie.org.mx; Ruiz L., Alejando; Mendoza C., Alfredo [Comision Federal de Electricidad, Campo Geotermico Los Azufres, Campamento Agua Fria, Michoacan (Mexico)

    2011-07-15

    A computer package, GeoSteamNet, was developed to simulate steam transport in a pipeline network of a geothermal field. The fluid motion is governed by the following basic principles: conservation of mass, linear momentum principle (Newton's second law or the Navier Stokes equations), and the first and second laws of thermodynamics. The second law of thermodynamics defines the direction of a spontaneous process, which is indirectly validated in the algorithm as vapor flows from high-to-low pressure, and heat flows from high-to-low temperatures. The nonlinear equations are solved with the Newton-Raphson method. Using the ActiveX component OrificeMeter, the steam-flow balance was calculated for power plants U-15 and U-16 in Los Azufres Geothermal Field, Mich., in February 2009. U-15 was fed by the production wells AZ-04, AZ-28, AZ-30, AZ-65D, and AZ-66, whereas wells AZ-28A, AZ-45, AZ-56, AZ-67, AZ-69D were connected to U-16. The analytical error is within {+-}4%, which is acceptable for practical purposes for steam-supply management, considering the uncertainties in parameters, such as pressure, temperature, pressure fluctuation at the wellhead, etc. The steam simulation results by GeoSteamNet for a hypothetical-pipeline network in a geothermal system with two production wells and a power plant illustrate its functionality. Several points need to be emphasized. For a specific geometry-pipeline network, there is only a certain amount of mass (vapor) that can be transported at a given pressure at the wellheads and the power plant. The construction and modification of a pipeline network is very expensive and the production of geothermal wells depends on many natural factors; therefore, there is need to conduct a tolerance study for each component of the network. A simulation study of the virtual-pipeline network for the design of a geothermal power plant can save money, effort, and time. [Spanish] Se desarrollo un paquete de computo, GeoSteamNet, para simular el

  15. Photocarcinogenesis and toxicity of benzoyl peroxide in hairless mice after simulated solar radiation

    Lerche, Catharina M; Philipsen, Peter A; Poulsen, Thomas

    2010-01-01

    with UV radiation. BPO can promote skin tumorigenesis in a mouse skin chemical carcinogenesis model. As acne vulgaris is frequently localized on sun-exposed areas, we investigated whether BPO or BPO-clin accelerates photocarcinogenesis in combination with simulated solar radiation (SSR) in 12 groups of 25...

  16. Acoustofluidics: Theory and simulation of streaming and radiation forces at ultrasound resonances in microfluidic devices

    Bruus, Henrik

    2009-01-01

    fields, which are directly related to the acoustic radiation force on single particles and to the acoustic streaming of the liquid. For the radiation pressure effects, there is good agreement between theory and simulation, while the numeric results for the acoustic streaming effects are more problematic...

  17. RadNet Air Data From Sacramento, CA

    This page presents radiation air monitoring and air filter analysis data for Sacramento, CA from EPA's RadNet system. RadNet is a nationwide network of monitoring stations that measure radiation in air, drinking water and precipitation.

  18. RadNet Air Data From Honolulu, HI

    This page presents radiation air monitoring and air filter analysis data for Honolulu, HI from EPA's RadNet system. RadNet is a nationwide network of monitoring stations that measure radiation in air, drinking water and precipitation.

  19. RadNet Air Data From Austin, TX

    This page presents radiation air monitoring and air filter analysis data for Austin, TX from EPA's RadNet system. RadNet is a nationwide network of monitoring stations that measure radiation in air, drinking water and precipitation.

  20. RadNet Air Data From Mason City, IA

    This page presents radiation air monitoring and air filter analysis data for Mason City, IA from EPA's RadNet system. RadNet is a nationwide network of monitoring stations that measure radiation in air, drinking water and precipitation.

  1. RadNet Air Data From Little Rock, AR

    This page presents radiation air monitoring and air filter analysis data for Little Rock, AR from EPA's RadNet system. RadNet is a nationwide network of monitoring stations that measure radiation in air, drinking water and precipitation.

  2. RadNet Air Data From Houston, TX

    This page presents radiation air monitoring and air filter analysis data for Houston, TX from EPA's RadNet system. RadNet is a nationwide network of monitoring stations that measure radiation in air, drinking water and precipitation.

  3. RadNet Air Data From Fort Smith, AR

    This page presents radiation air monitoring and air filter analysis data for Fort Smith, AR from EPA's RadNet system. RadNet is a nationwide network of monitoring stations that measure radiation in air, drinking water and precipitation.

  4. RadNet Air Data From Orlando, FL

    This page presents radiation air monitoring and air filter analysis data for Orlando, FL from EPA's RadNet system. RadNet is a nationwide network of monitoring stations that measure radiation in air, drinking water and precipitation.

  5. Publicly Released Prompt Radiation Spectra Suitable for Nuclear Detonation Simulations

    2017-03-01

    emission. During the Hiroshima and Nagasaki bombings , the prompt radiation contributed from 40%-70% of the free-in-air dose depending on distance from...intermediate- and low-yield thermonuclear weapons for initial radiation shielding calculations No Gritzner, et al. 1976 ( EM -1, Low, Henre...DNA 4267F ( EM -1 Fission) Neutron Gritzner, et al. 1976 1.00 x 1023 Glasstone (Thermonuclear) Neutron Glasstone & Dolan 1977 1.445 x 1023 ORNL-TM

  6. Numerical simulation of thermal behaviors of a clothed human body with evaluation of indoor solar radiation

    Mao, Aihua; Luo, Jie; Li, Yi

    2017-01-01

    Highlights: • Solar radiation evaluation is integrated with the thermal transfer in clothed humans. • Thermal models are developed for clothed humans exposed in indoor solar radiation. • The effect of indoor solar radiation on humans can be predicted in different situations in living. • The green solar energy can be efficiently utilized in the building development. - Abstract: Solar radiation is a valuable green energy, which is important in achieving a successful building design for thermal comfort in indoor environment. This paper considers solar radiation indoors into the transient thermal transfer models of a clothed human body and offers a new numerical method to analyze the dynamic thermal status of a clothed human body under different solar radiation incidences. The evaluation model of solar radiation indoors and a group of coupled thermal models of the clothed human body are developed and integrated. The simulation capacities of these integrated models are validated through a comparison between the predicted results and the experimental data in reference. After that, simulation cases are also conducted to show the influence of solar radiation on the thermal status of individual clothed body segments when the human body is staying indoors in different seasons. This numerical simulation method provides a useful tool to analyze the thermal status of clothed human body under different solar radiation incidences indoors and thus enables the architect to efficiently utilize the green solar energy in building development.

  7. Reconfiguration of distribution nets

    Latorre Bayona, Gerardo; Angarita Marquez, Jorge Luis

    2000-01-01

    Starting of the location of the reconfiguration problem inside the context of the operation of distribution nets, of the quality indicators definition and of the presentation of the alternatives more used for reduction of technical losses, they are related diverse reconfiguration methodologies proposed in the technical literature, pointing out their three principals limitations; also are presents the results of lost obtained starting from simulation works carried out in distribution circuits of the ESSA ESP, which permitting to postulate the reconfiguration of nets like an excellent alternative to reduce technical losses

  8. The Net-Generation Interior Design Student: An Exploratory Study Assessing Learning and Engagement within a Computer Simulation Environment

    Peterson, Julie Ellen

    2009-01-01

    The first purpose of this experimental study was to determine if there were effects on achievement between traditional pencil-and-paper instructional strategies and computer simulated instructional strategies used to teach interior design business ethics. The second purpose was to determine the level of engagement of interior design students using…

  9. Validation databases for simulation models: aboveground biomass and net primary productive, (NPP) estimation using eastwide FIA data

    Jennifer C. Jenkins; Richard A. Birdsey

    2000-01-01

    As interest grows in the role of forest growth in the carbon cycle, and as simulation models are applied to predict future forest productivity at large spatial scales, the need for reliable and field-based data for evaluation of model estimates is clear. We created estimates of potential forest biomass and annual aboveground production for the Chesapeake Bay watershed...

  10. Simulated Space Radiation and Weightlessness: Vascular-Bone Coupling Mechanisms to Preserve Skeletal Health

    Globus, R. K.; Alwood, J.; Tahimic, C.; Schreurs, A.-S.; Shirazi-Fard, Y.; Terada, M.; Zaragoza, J.; Truong, T.; Bruns, K.; Castillo, A.; hide

    2018-01-01

    We examined experimentally the effects of radiation and/or simulated weightlessness by hindlimb unloading on bone and blood vessel function either after a short period or at a later time after transient exposures in adult male, C57Bl6J mice. In sum, recent findings from our studies show that in the short term, ionizing radiation and simulate weightlessness cause greater deficits in blood vessels when combined compared to either challenge alone. In the long term, heavy ion radiation, but not unloading, can lead to persistent, adverse consequences for bone and vessel function, possibly due to oxidative stress-related pathways.

  11. Simulation of space radiation effects on polyimide film materials for high temperature applications. Final report

    Fogdall, L.B.; Cannaday, S.S.

    1977-11-01

    Space environment effects on candidate materials for the solar sail film are determined. Polymers, including metallized polyimides that might be suitable solar radiation receivers, were exposed to combined proton and solar electromagnetic radiation. Each test sample was weighted, to simulate the tension on the polymer when it is stretched into near-planar shape while receiving solar radiation. Exposure rates up to 16 times that expected in Earth orbit were employed, to simulate near-sun solar sailing conditions. Sample appearance, elongation, and shrinkage were monitored, noted, and documented in situ. Thermosetting polyimides showed less degradation or visual change in appearance than thermoplastics

  12. Three-dimensional simulation of super-radiant Smith-Purcell radiation

    Li, D.; Imasaki, K.; Yang, Z.; Park, Gun-Sik

    2006-01-01

    A simulation of coherent and super-radiant Smith-Purcell radiation is performed in the gigahertz regime using a three-dimensional particle-in-cell code. The simulation model supposes a rectangular grating to be driven by a single electron bunch and a train of periodic bunches, respectively. The true Smith-Purcell radiation is distinguished from the evanescent wave, which has an angle independent frequency lower than the minimum allowed Smith-Purcell frequency. We also find that the super-radiant radiations excited by periodic bunches are emitted at higher harmonics of the bunching frequency and at the corresponding Smith-Purcell angles

  13. Virtual reality-based simulation system for nuclear and radiation safety SuperMC/RVIS

    He, T.; Hu, L.; Long, P.; Shang, L.; Zhou, S.; Yang, Q.; Zhao, J.; Song, J.; Yu, S.; Cheng, M.; Hao, L., E-mail: liqin.hu@fds.org.cn [Chinese Academy of Sciences, Key Laboratory of Neutronics and Radiation Safety, Institute of Nuclear Energy Safety Technology, Hefei, Anhu (China)

    2015-07-01

    The suggested work scenarios in radiation environment need to be iterative optimized according to the ALARA principle. Based on Virtual Reality (VR) technology and high-precision whole-body computational voxel phantom, a virtual reality-based simulation system for nuclear and radiation safety named SuperMC/RVIS has been developed for organ dose assessment and ALARA evaluation of work scenarios in radiation environment. The system architecture, ALARA evaluation strategy, advanced visualization methods and virtual reality technology used in SuperMC/RVIS are described. A case is presented to show its dose assessment and interactive simulation capabilities. (author)

  14. Virtual reality-based simulation system for nuclear and radiation safety SuperMC/RVIS

    He, T.; Hu, L.; Long, P.; Shang, L.; Zhou, S.; Yang, Q.; Zhao, J.; Song, J.; Yu, S.; Cheng, M.; Hao, L.

    2015-01-01

    The suggested work scenarios in radiation environment need to be iterative optimized according to the ALARA principle. Based on Virtual Reality (VR) technology and high-precision whole-body computational voxel phantom, a virtual reality-based simulation system for nuclear and radiation safety named SuperMC/RVIS has been developed for organ dose assessment and ALARA evaluation of work scenarios in radiation environment. The system architecture, ALARA evaluation strategy, advanced visualization methods and virtual reality technology used in SuperMC/RVIS are described. A case is presented to show its dose assessment and interactive simulation capabilities. (author)

  15. Estimativa do saldo de radiação em girassol como função da radiação solar global Estimation of net radiation in sunflower as a function of solar radiation

    Arno B Heldwein

    2012-02-01

    Full Text Available Objetivou-se com este trabalho a obtenção de modelos para a estimativa do saldo de radiação (Q* a partir da radiação solar global incidente (Rg sobre dosseis de plantas de girassol. Os experimentos foram conduzidos na área experimental da Universidade Federal de Santa Maria, nos anos de 2007, 2008 e 2009. O Q* foi medido com saldos radiômetros instalados acima das plantas e a Rg em estações meteorológicas automáticas. Para fins de cálculo foram efetuadas as somas diárias de Q* e de Rg, obtendo-se a relação entre Q* e Rg para cada dia. Obtiveram-se, então, modelos com elevado coeficiente de determinação e baixo RQME no teste entre valores medidos e estimados de um banco de dados independente, indicando precisão na estimativa do saldo de radiação em dosseis de girassol, independendo da época de cultivo no ano. A função linear geral obtida com dados de diferentes épocas de cultivo foi: Q* = 0,5285 Rg (R² = 0,95, que no teste apresentou RQME = 1,04 MJ m-2 d-1. Conclui-se que o saldo de radiação (Q* pode ser estimado utilizando-se a radiação solar global medida em estações automáticas, com precisão suficiente para os diferentes fins na agrometeorologia do girassol.This study aimed to develop models for estimating the net radiation (Q * from the incident solar radiation (Rg on canopies of sunflower plants. The experiments were conducted at the Plant Science Department of the Federal University of Santa Maria in 2007, 2008 and 2009 years. Q* was measured by net radiometers above the plants and Rg by automatic weather stations. For purposes of calculation, daily sums of Q* and Rg were performed, obtaining the relationship between Q* and Rg for each day. Models with high coefficient of determination and low RQME were obtained in test between measured and estimated values from an independent database, indicating precision to estimate net radiation in sunflower canopies, regardless of cultivation time in year. The general

  16. A simulation for radioactive decay and the absorption of radiation

    Anon.

    1987-01-01

    The purpose of this article is to derive and discuss these exponential laws for the benefit of teachers and interested pupils, and to discuss a simulation of the above phenoma should radioactive sources and Geiger-Mueller counters not be available in any particular school laboratory. The simulation can also be done by computer

  17. Net Locality

    de Souza e Silva, Adriana Araujo; Gordon, Eric

    Provides an introduction to the new theory of Net Locality and the profound effect on individuals and societies when everything is located or locatable. Describes net locality as an emerging form of location awareness central to all aspects of digital media, from mobile phones, to Google Maps......, to location-based social networks and games, such as Foursquare and facebook. Warns of the threats these technologies, such as data surveillance, present to our sense of privacy, while also outlining the opportunities for pro-social developments. Provides a theory of the web in the context of the history...... of emerging technologies, from GeoCities to GPS, Wi-Fi, Wiki Me, and Google Android....

  18. Simulation of the Focal Spot of the Accelerator Bremsstrahlung Radiation

    Sorokin, V.; Bespalov, V.

    2016-06-01

    Testing of thick-walled objects by bremsstrahlung radiation (BR) is primarily performed via high-energy quanta. The testing parameters are specified by the focal spot size of the high-energy bremsstrahlung radiation. In determining the focal spot size, the high- energy BR portion cannot be experimentally separated from the low-energy BR to use high- energy quanta only. The patterns of BR focal spot formation have been investigated via statistical modeling of the radiation transfer in the target material. The distributions of BR quanta emitted by the target for different energies and emission angles under normal distribution of the accelerated electrons bombarding the target have been obtained, and the ratio of the distribution parameters has been determined.

  19. Local dose enhancement in radiation therapy: Monte Carlo simulation study

    Silva, Laura E. da; Nicolucci, Patricia

    2014-01-01

    The development of nanotechnology has boosted the use of nanoparticles in radiation therapy in order to achieve greater therapeutic ratio between tumor and healthy tissues. Gold has been shown to be most suitable to this task due to the high biocompatibility and high atomic number, which contributes to a better in vivo distribution and for the local energy deposition. As a result, this study proposes to study, nanoparticle in the tumor cell. At a range of 11 nm from the nanoparticle surface, results have shown an absorbed dose 141 times higher for the medium with the gold nanoparticle compared to the water for an incident energy spectrum with maximum photon energy of 50 keV. It was also noted that when only scattered radiation is interacting with the gold nanoparticles, the dose was 134 times higher compared to enhanced local dose that remained significant even for scattered radiation. (author)

  20. Ozone database in support of CMIP5 simulations: results and corresponding radiative forcing

    I. Cionni

    2011-11-01

    total column ozone is overestimated in the southern polar latitudes during spring and tropospheric column ozone is slightly underestimated. Vertical profiles of tropospheric ozone are broadly consistent with ozonesondes and in-situ measurements, with some deviations in regions of biomass burning. The tropospheric ozone radiative forcing (RF from the 1850s to the 2000s is 0.23 W m−2, lower than previous results. The lower value is mainly due to (i a smaller increase in biomass burning emissions; (ii a larger influence of stratospheric ozone depletion on upper tropospheric ozone at high southern latitudes; and possibly (iii a larger influence of clouds (which act to reduce the net forcing compared to previous radiative forcing calculations. Over the same period, decreases in stratospheric ozone, mainly at high latitudes, produce a RF of −0.08 W m−2, which is more negative than the central Intergovernmental Panel on Climate Change (IPCC Fourth Assessment Report (AR4 value of −0.05 W m−2, but which is within the stated range of −0.15 to +0.05 W m−2. The more negative value is explained by the fact that the regression model simulates significant ozone depletion prior to 1979, in line with the increase in EESC and as confirmed by CCMs, while the AR4 assumed no change in stratospheric RF prior to 1979. A negative RF of similar magnitude persists into the future, although its location shifts from high latitudes to the tropics. This shift is due to increases in polar stratospheric ozone, but decreases in tropical lower stratospheric ozone, related to a strengthening of the Brewer-Dobson circulation, particularly through the latter half of the 21st century. Differences in trends in tropospheric ozone among the four RCPs are mainly driven by different methane concentrations, resulting in a range of tropospheric ozone RFs between 0.4 and 0.1 W m−2 by 2100. The ozone dataset described here has been released for

  1. Development of Radio Frequency Antenna Radiation Simulation Software

    Mohamad Idris Taib; Rozaimah Abd Rahim; Noor Ezati Shuib; Wan Saffiey Wan Abdullah

    2014-01-01

    Antennas are widely used national wide for radio frequency propagation especially for communication system. Radio frequency is electromagnetic spectrum from 10 kHz to 300 GHz and non-ionizing. These radiation exposures to human being have radiation hazard risk. This software was under development using LabVIEW for radio frequency exposure calculation. For the first phase of this development, software purposely to calculate possible maximum exposure for quick base station assessment, using prediction methods. This software also can be used for educational purpose. Some results of this software are comparing with commercial IXUS and free ware NEC software. (author)

  2. Monte Carlo simulations of the radiation environment for the CMS experiment

    Mallows, S., E-mail: sophie.mallows@cern.ch [KIT, Karlsruhe (Germany); Azhgirey, I.; Bayshev, I. [IHEP, Protvino (Russian Federation); Bergstrom, I.; Cooijmans, T.; Dabrowski, A.; Glöggler, L.; Guthoff, M. [CERN, Geneva (Switzerland); Kurochkin, I. [IHEP, Protvino (Russian Federation); Vincke, H.; Tajeda, S. [CERN, Geneva (Switzerland)

    2016-07-11

    Monte Carlo radiation transport codes are used by the CMS Beam Radiation Instrumentation and Luminosity (BRIL) project to estimate the radiation levels due to proton–proton collisions and machine induced background. Results are used by the CMS collaboration for various applications: comparison with detector hit rates, pile-up studies, predictions of radiation damage based on various models (Dose, NIEL, DPA), shielding design, estimations of residual dose environment. Simulation parameters, and the maintenance of the input files are summarized, and key results are presented. Furthermore, an overview of additional programs developed by the BRIL project to meet the specific needs of CMS community is given.

  3. Monte Carlo simulations of the radiation environment for the CMS Experiment

    AUTHOR|(CDS)2068566; Bayshev, I.; Bergstrom, I.; Cooijmans, T.; Dabrowski, A.; Glöggler, L.; Guthoff, M.; Kurochkin, I.; Vincke, H.; Tajeda, S.

    2016-01-01

    Monte Carlo radiation transport codes are used by the CMS Beam Radiation Instrumentation and Luminosity (BRIL) project to estimate the radiation levels due to proton-proton collisions and machine induced background. Results are used by the CMS collaboration for various applications: comparison with detector hit rates, pile-up studies, predictions of radiation damage based on various models (Dose, NIEL, DPA), shielding design, estimations of residual dose environment. Simulation parameters, and the maintenance of the input files are summarised, and key results are presented. Furthermore, an overview of additional programs developed by the BRIL project to meet the specific needs of CMS community is given.

  4. Radiation exchange between persons and surfaces for building energy simulations

    Vorre, Mette Havgaard; Jensen, Rasmus Lund; Dreau, Jerome Le

    2015-01-01

    Thermal radiation within buildings is a significant component of thermal comfort. Typically the methods applied for calculating view factors between a person and its building surfaces requires great computational time. This research developed a view factor calculation method suitable for building...

  5. Review of radiation sources, calibration facilities and simulated workplace fields

    Lacoste, V., E-mail: veronique.lacoste@irsn.f [Institut de Radioprotection et de Surete Nucleaire, BP3, Bat. 159, F-13115 Saint-Paul Lez Durance (France)

    2010-12-15

    A review on radiation sources, calibration facilities and realistic fields is presented and examples are given. The main characteristics of the fields are shortly described together with their domain of applications. New emerging fields are also mentioned and the question of needs for additional calibration fields is raised.

  6. Computer simulation of heating of biological tissue during laser radiation

    Bojanic, S.; Sreckovic, M.

    1995-01-01

    Computer model is based on an implicit finite difference scheme to solve the diffusion equation for light distribution and the bio-heat equation. A practical application of the model is to calculate the temperature distributions during thermal coagulation of prostate by radiative heating. (author)

  7. Simulation of Hamming Coding and Decoding for Microcontroller Radiation Hardening

    Rehab I. Abdul Rahman; Mazhar B. Tayel

    2015-01-01

    This paper presents a method of hardening the 8051 micro-controller, able to assure reliable operation in the presence of bit flips caused by radiation. Aiming at avoiding such faults in the 8051 micro-controller, Hamming code protection was used in its SRAM memory and registers. A VHDL code has been used for this hamming code protection.

  8. Discrete Event Simulation Model of the Polaris 2.1 Gamma Ray Imaging Radiation Detection Device

    2016-06-01

    release; distribution is unlimited DISCRETE EVENT SIMULATION MODEL OF THE POLARIS 2.1 GAMMA RAY IMAGING RADIATION DETECTION DEVICE by Andres T...ONLY (Leave blank) 2. REPORT DATE June 2016 3. REPORT TYPE AND DATES COVERED Master’s thesis 4. TITLE AND SUBTITLE DISCRETE EVENT SIMULATION MODEL...modeled. The platform, Simkit, was utilized to create a discrete event simulation (DES) model of the Polaris. After carefully constructing the DES

  9. Measurements and simulations of the radiation exposure to aircraft crew workplaces due to cosmic radiation in the atmosphere

    Beck, P.; Latocha, M.; Dorman, L.; Pelliccioni, M.; Rollet, S.

    2007-01-01

    As required by the European Directive 96/29/Euratom, radiation exposure due to natural ionizing radiation has to be taken into account at workplaces if the effective dose could become more than 1 mSv per year. An example of workers concerned by this directive is aircraft crew due to cosmic radiation exposure in the atmosphere. Extensive measurement campaigns on board aircraft have been carried out to assess ambient dose equivalent. A consortium of European dosimetry institutes within EURADOS WG5 summarized experimental data and results of calculations, together with detailed descriptions of the methods for measurements and calculations. The radiation protection quantity of interest is the effective dose, E (ISO). The comparison of results by measurements and calculations is done in terms of the operational quantity ambient dose equivalent, H*(10). This paper gives an overview of the EURADOS Aircraft Crew In-Flight Database and it presents a new empirical model describing fitting functions for this data. Furthermore, it describes numerical simulations performed with the Monte Carlo code FLUKA-2005 using an updated version of the cosmic radiation primary spectra. The ratio between ambient dose equivalent and effective dose at commercial flight altitudes, calculated with FLUKA-2005, is discussed. Finally, it presents the aviation dosimetry model AVIDOS based on FLUKA-2005 simulations for routine dose assessment. The code has been developed by Austrian Research Centers (ARC) for the public usage (http://avidos.healthphysics.at. (authors)

  10. Simulations of depleted CMOS sensors for high-radiation environments

    Liu, J.; Bhat, S.; Breugnon, P.; Caicedo, I.; Chen, Z.; Degerli, Y.; Godiot-Basolo, S.; Guilloux, F.; Hemperek, T.; Hirono, T.; Hügging, F.; Krüger, H.; Moustakas, K.; Pangaud, P.; Rozanov, A.; Rymaszewski, P.; Schwemling, P.; Wang, M.; Wang, T.; Wermes, N.; Zhang, L.

    2017-01-01

    After the Phase II upgrade for the Large Hadron Collider (LHC), the increased luminosity requests a new upgraded Inner Tracker (ITk) for the ATLAS experiment. As a possible option for the ATLAS ITk, a new pixel detector based on High Voltage/High Resistivity CMOS (HV/HR CMOS) technology is under study. Meanwhile, a new CMOS pixel sensor is also under development for the tracker of Circular Electron Position Collider (CEPC). In order to explore the sensor electric properties, such as the breakdown voltage and charge collection efficiency, 2D/3D Technology Computer Aided Design (TCAD) simulations have been performed carefully for the above mentioned both of prototypes. In this paper, the guard-ring simulation for a HV/HR CMOS sensor developed for the ATLAS ITk and the charge collection efficiency simulation for a CMOS sensor explored for the CEPC tracker will be discussed in details. Some comparisons between the simulations and the latest measurements will also be addressed.

  11. Simulation study of radiation damage induced by energetic helium nuclei

    Hoang Dac Luc; Vo Tuong Hanh; Hoang Dac Dat

    2003-01-01

    High energy alpha particles produced by neutron-induced nuclear reactions can damage severely reactor materials. Simulation of this process is described using theoretical calculation and ion irradiation experiments at different displacement doses and Helium doses. (author)

  12. Simulation study of radiation damage induced by energetic helium nuclei

    Hoang Dac Luc; Hoang Dac Dat

    2003-01-01

    High energy alpha particles produced by neutron-induced nuclear reactions can damage severely reactor materials. Simulation of this process is described using theoretical calculation and ion irradiation experiments at different displacement doses and Helium doses.

  13. DSMC simulation of two-phase plume flow with UV radiation

    Li, Jie; Liu, Ying; Wang, Ning; Jin, Ling [College of Aerospace Science and Engineering, National University of Defense Technology, Changsha, Hunan, 410073 (China)

    2014-12-09

    Rarefied gas-particle two-phase plume in which the phase of particles is liquid or solid flows from a solid propellant rocket of hypersonic vehicle flying at high altitudes, the aluminum oxide particulates not only impact the rarefied gas flow properties, but also make a great difference to plume radiation signature, so the radiation prediction of the rarefied gas-particle two-phase plume flow is very important for space target detection of hypersonic vehicles. Accordingly, this project aims to study the rarefied gas-particle two-phase flow and ultraviolet radiation (UV) characteristics. Considering a two-way interphase coupling of momentum and energy, the direct simulation Monte Carlo (DSMC) method is developed for particle phase change and the particle flow, including particulate collision, coalescence as well as separation, and a Monte Carlo ray trace model is implemented for the particulate UV radiation. A program for the numerical simulation of the gas-particle two-phase flow and radiation in which the gas flow nonequilibrium is strong is implemented as well. Ultraviolet radiation characteristics of the particle phase is studied based on the calculation of the flow field coupled with the radiation calculation, the radiation model for different size particles is analyzed, focusing on the effects of particle emission, absorption, scattering as well as the searchlight emission of the nozzle. A new approach may be proposed to describe the rarefied gas-particle two-phase plume flow and radiation transfer characteristics in this project.

  14. DSMC simulation of two-phase plume flow with UV radiation

    Li, Jie; Liu, Ying; Wang, Ning; Jin, Ling

    2014-12-01

    Rarefied gas-particle two-phase plume in which the phase of particles is liquid or solid flows from a solid propellant rocket of hypersonic vehicle flying at high altitudes, the aluminum oxide particulates not only impact the rarefied gas flow properties, but also make a great difference to plume radiation signature, so the radiation prediction of the rarefied gas-particle two-phase plume flow is very important for space target detection of hypersonic vehicles. Accordingly, this project aims to study the rarefied gas-particle two-phase flow and ultraviolet radiation (UV) characteristics. Considering a two-way interphase coupling of momentum and energy, the direct simulation Monte Carlo (DSMC) method is developed for particle phase change and the particle flow, including particulate collision, coalescence as well as separation, and a Monte Carlo ray trace model is implemented for the particulate UV radiation. A program for the numerical simulation of the gas-particle two-phase flow and radiation in which the gas flow nonequilibrium is strong is implemented as well. Ultraviolet radiation characteristics of the particle phase is studied based on the calculation of the flow field coupled with the radiation calculation, the radiation model for different size particles is analyzed, focusing on the effects of particle emission, absorption, scattering as well as the searchlight emission of the nozzle. A new approach may be proposed to describe the rarefied gas-particle two-phase plume flow and radiation transfer characteristics in this project.

  15. Cerenkov radiation simulation in the Auger water ground detector

    Le Van Ngoc; Vo Van Thuan; Dang Quang Thieu

    2003-01-01

    The simulation of response of the Auger water Cerenkov ground detector to atmospheric shower muons in practically needed for the experimental research of cosmic rays at extreme energies. We consider here a simulation model for the process of emission and diffusion of Cerenkov photons concerned with muons moving through the detector volume with the velocity greater than the phase velocity of light in the water on purpose to define photons producing signal in the detector. (author)

  16. Monte Carlo and analytic simulations in nanoparticle-enhanced radiation therapy

    Paro AD

    2016-09-01

    Full Text Available Autumn D Paro,1 Mainul Hossain,2 Thomas J Webster,1,3,4 Ming Su1,4 1Department of Chemical Engineering, Northeastern University, Boston, MA, USA; 2NanoScience Technology Center and School of Electrical Engineering and Computer Science, University of Central Florida, Orlando, Florida, USA; 3Excellence for Advanced Materials Research, King Abdulaziz University, Jeddah, Saudi Arabia; 4Wenzhou Institute of Biomaterials and Engineering, Chinese Academy of Science, Wenzhou Medical University, Zhejiang, People’s Republic of China Abstract: Analytical and Monte Carlo simulations have been used to predict dose enhancement factors in nanoparticle-enhanced X-ray radiation therapy. Both simulations predict an increase in dose enhancement in the presence of nanoparticles, but the two methods predict different levels of enhancement over the studied energy, nanoparticle materials, and concentration regime for several reasons. The Monte Carlo simulation calculates energy deposited by electrons and photons, while the analytical one only calculates energy deposited by source photons and photoelectrons; the Monte Carlo simulation accounts for electron–hole recombination, while the analytical one does not; and the Monte Carlo simulation randomly samples photon or electron path and accounts for particle interactions, while the analytical simulation assumes a linear trajectory. This study demonstrates that the Monte Carlo simulation will be a better choice to evaluate dose enhancement with nanoparticles in radiation therapy. Keywords: nanoparticle, dose enhancement, Monte Carlo simulation, analytical simulation, radiation therapy, tumor cell, X-ray 

  17. Numerical Simulations of Turbulent Molecular Clouds Regulated by Radiation Feedback Forces. II. Radiation-Gas Interactions and Outflows

    Raskutti, Sudhir; Ostriker, Eve C.; Skinner, M. Aaron

    2017-12-01

    Momentum deposition by radiation pressure from young, massive stars may help to destroy molecular clouds and unbind stellar clusters by driving large-scale outflows. We extend our previous numerical radiation hydrodynamic study of turbulent star-forming clouds to analyze the detailed interaction between non-ionizing UV radiation and the cloud material. Our simulations trace the evolution of gas and star particles through self-gravitating collapse, star formation, and cloud destruction via radiation-driven outflows. These models are idealized in that we include only radiation feedback and adopt an isothermal equation of state. Turbulence creates a structure of dense filaments and large holes through which radiation escapes, such that only ˜50% of the radiation is (cumulatively) absorbed by the end of star formation. The surface density distribution of gas by mass as seen by the central cluster is roughly lognormal with {σ }{ln{{Σ }}}=1.3{--}1.7, similar to the externally projected surface density distribution. This allows low surface density regions to be driven outwards to nearly 10 times their initial escape speed {v}{esc}. Although the velocity distribution of outflows is broadened by the lognormal surface density distribution, the overall efficiency of momentum injection to the gas cloud is reduced because much of the radiation escapes. The mean outflow velocity is approximately twice the escape speed from the initial cloud radius. Our results are also informative for understanding galactic-scale wind driving by radiation, in particular, the relationship between velocity and surface density for individual outflow structures and the resulting velocity and mass distributions arising from turbulent sources.

  18. Comprehensive MRI simulation methodology using a dedicated MRI scanner in radiation oncology for external beam radiation treatment planning

    Paulson, Eric S.; Erickson, Beth; Schultz, Chris; Allen Li, X.

    2015-01-01

    Purpose: The use of magnetic resonance imaging (MRI) in radiation oncology is expanding rapidly, and more clinics are integrating MRI into their radiation therapy workflows. However, radiation therapy presents a new set of challenges and places additional constraints on MRI compared to diagnostic radiology that, if not properly addressed, can undermine the advantages MRI offers for radiation treatment planning (RTP). The authors introduce here strategies to manage several challenges of using MRI for virtual simulation in external beam RTP. Methods: A total of 810 clinical MRI simulation exams were performed using a dedicated MRI scanner for external beam RTP of brain, breast, cervix, head and neck, liver, pancreas, prostate, and sarcoma cancers. Patients were imaged in treatment position using MRI-optimal immobilization devices. Radiofrequency (RF) coil configurations and scan protocols were optimized based on RTP constraints. Off-resonance and gradient nonlinearity-induced geometric distortions were minimized or corrected prior to using images for RTP. A multidisciplinary MRI simulation guide, along with window width and level presets, was created to standardize use of MR images during RTP. A quality assurance program was implemented to maintain accuracy and repeatability of MRI simulation exams. Results: The combination of a large bore scanner, high field strength, and circumferentially wrapped, flexible phased array RF receive coils permitted acquisition of thin slice images with high contrast-to-noise ratio (CNR) and image intensity uniformity, while simultaneously accommodating patient setup and immobilization devices. Postprocessing corrections and alternative acquisition methods were required to reduce or correct off-resonance and gradient nonlinearity induced geometric distortions. Conclusions: The methodology described herein contains practical strategies the authors have implemented through lessons learned performing clinical MRI simulation exams. In

  19. Comprehensive MRI simulation methodology using a dedicated MRI scanner in radiation oncology for external beam radiation treatment planning

    Paulson, Eric S., E-mail: epaulson@mcw.edu [Department of Radiation Oncology, Medical College of Wisconsin, Milwaukee, Wisconsin 53226 and Department of Radiology, Medical College of Wisconsin, Milwaukee, Wisconsin 53226 (United States); Erickson, Beth; Schultz, Chris; Allen Li, X. [Department of Radiation Oncology, Medical College of Wisconsin, Milwaukee, Wisconsin 53226 (United States)

    2015-01-15

    Purpose: The use of magnetic resonance imaging (MRI) in radiation oncology is expanding rapidly, and more clinics are integrating MRI into their radiation therapy workflows. However, radiation therapy presents a new set of challenges and places additional constraints on MRI compared to diagnostic radiology that, if not properly addressed, can undermine the advantages MRI offers for radiation treatment planning (RTP). The authors introduce here strategies to manage several challenges of using MRI for virtual simulation in external beam RTP. Methods: A total of 810 clinical MRI simulation exams were performed using a dedicated MRI scanner for external beam RTP of brain, breast, cervix, head and neck, liver, pancreas, prostate, and sarcoma cancers. Patients were imaged in treatment position using MRI-optimal immobilization devices. Radiofrequency (RF) coil configurations and scan protocols were optimized based on RTP constraints. Off-resonance and gradient nonlinearity-induced geometric distortions were minimized or corrected prior to using images for RTP. A multidisciplinary MRI simulation guide, along with window width and level presets, was created to standardize use of MR images during RTP. A quality assurance program was implemented to maintain accuracy and repeatability of MRI simulation exams. Results: The combination of a large bore scanner, high field strength, and circumferentially wrapped, flexible phased array RF receive coils permitted acquisition of thin slice images with high contrast-to-noise ratio (CNR) and image intensity uniformity, while simultaneously accommodating patient setup and immobilization devices. Postprocessing corrections and alternative acquisition methods were required to reduce or correct off-resonance and gradient nonlinearity induced geometric distortions. Conclusions: The methodology described herein contains practical strategies the authors have implemented through lessons learned performing clinical MRI simulation exams. In

  20. A simulation method for the stability analysis of landscape scenarios by using a NetLogo application in GIS environment

    Gobattoni, Federica; Lauro, Giuliana; Leone, Antonio; Monaco, Roberto; Pelorosso, Raffaele

    2010-05-01

    could be able to predict the response of the landscape working as a unique system, are expected to advance through a development of sustainable planning strategies and to evaluate the equilibrium-non equilibrium status of landscape evolution and the availability of vital resources in space and time. In this context mathematical models adapted in GIS environment may really give an heavy contribution in such a complex problem- solving, providing a real and concrete Decision System Support. An integrated GIS (Geographic Information System)-based approach was developed (G. Lauro, R. Monaco, 2008) combining an ecological graph model for the analysis of the relationship between spatial pattern and ecological flows and a mathematical model, based on a system of two nonlinear differential equations, that studies meta-stability and bifurcation phenomena. These equations are mainly based on a balance law between a logistic growth of bio-energy and its reduction due to limiting factors coming from environmental constraints. The energy exchange among them will be more or less strong depending on the degree of permeability of the barriers which can obstruct the energy passage from each "landscape unit" to the other. Through NetLogo, a cross-platform multi-agent programmable modelling environment, a completely automatic GIS-based mathematical model, based on the ecological graph and on the cited two differential equations, is presented and discussed here. A study case in Central Italy is analysed to better underline the importance of such a user friendly model in GIS environment.

  1. A radiation monitoring system model for the Laguna Verde nuclear power training simulator

    Ocampo, M.H.; DeAlbornoz, B.A.

    1988-01-01

    A model for the Radiation Monitoring System of the Laguna Verde Boiling Water Reactor training simulator is presented. This model comprises enough definitions to assure interactions with the processes related, directly or indirectly, with the transport of radioisotopes. It is capable of following a dynamic behavior of the plant so an operator could be trained to become aware of nuclear radiation hazards. The model is composed of three parts: the electronics for the Process and Area Radiation Monitoring System; a lumped parameter transport model for the most representative radioisotopes; and the interactions with the modeled processes as well as with process not being simulated. The first part represents the radiation monitor controls in the vertical board panels of the nuclear station. The second part allows the carrying of nuclear isotopes between processes. The third part defines the way that the process interacts with the electronics at the point of release to environment or the point of detection. Each part of the model has been tested individually, and the transport model has been incorporated as a part of each process required to simulate nuclear radiation. The model parameters has been calculated using typical BWR nuclear radiation data, and Laguna Verde heat balance data at 100% design power. However, tunning will be necessary once the Simulator is integrated and tested. The tunning allows each detecting channel to behave as expected

  2. Numerical simulations for radiation hydrodynamics. 2: Transport limit

    Dai, W.W.; Woodward, P.R.

    2000-01-01

    A finite difference scheme is proposed for two-dimensional radiation hydrodynamical equations in the transport limit. The scheme is of Godunov-type, in which the set of time-averaged flux needed in the scheme is calculated through Riemann problems solved. In the scheme, flow signals are explicitly treated, while radiation signals are implicitly treated. Flow fields and radiation fields are updated simultaneously. An iterative approach is proposed to solve the set of nonlinear algebraic equations arising from the implicitness of the scheme. The sweeping method used in the scheme significantly reduces the number of iterations or computer CPU time needed. A new approach to further accelerate the convergence is proposed, which further reduces the number of iterations needed by more than one order. No matter how many cells radiation signals propagate in one time step, only an extremely small number of iterations are needed in the scheme, and each iteration costs only about 0.8% of computer CPU time which is needed for one time step of a second order accurate and fully explicit scheme. Two-dimensional problems are treated through a dimensionally split technique. Therefore, iterations for solving the set of algebraic equations are carried out only in each one-dimensional sweep. Through numerical examples it is shown that the scheme keeps the principle advantages of Godunov schemes for flow motion. In the time scale of flow motion numerical results are the same as those obtained from a second order accurate and fully explicit scheme. The acceleration of the convergence proposed in this paper may be directly applied to other hyperbolic systems. This study is important for laser fusion and astrophysics

  3. Simulation analysis of radiation fields inside phantoms for neutron irradiation

    Satoh, Daiki; Takahashi, Fumiaki; Endo, Akira; Ohmachi, Y.; Miyahara, N.

    2007-01-01

    Radiation fields inside phantoms have been calculated for neutron irradiation. Particle and heavy-ion transport code system PHITS was employed for the calculation. Energy and size dependences of neutron dose were analyzed using tissue equivalent spheres of different size. A voxel phantom of mouse was developed based on CT images of an 8-week-old male C3H/HeNs mouse. Deposition energy inside the mouse was calculated for 2- and 10-MeV neutron irradiation. (author)

  4. The cloud radiation impact from optics simulation and airborne observation

    Melnikova, Irina; Kuznetsov, Anatoly; Gatebe, Charles

    2017-02-01

    The analytical approach of inverse asymptotic formulas of the radiative transfer theory is used for solving inverse problems of cloud optics. The method has advantages because it does not impose strict constraints, but it is tied to the desired solution. Observations are accomplished in extended stratus cloudiness, above a homogeneous ocean surface. Data from NASA`s Cloud Absorption Radiometer (CAR) during two airborne experiments (SAFARI-2000 and ARCTAS-2008) were analyzed. The analytical method of inverse asymptotic formulas was used to retrieve cloud optical parameters (optical thickness, single scattering albedo and asymmetry parameter of the phase function) and ground albedo in all 8 spectral channels independently. The method is free from a priori restrictions and there is no links to parameters, and it has been applied to data set of different origin and geometry of observations. Results obtained from different airborne, satellite and ground radiative experiments appeared consistence and showed common features of values of cloud parameters and its spectral dependence (Vasiluev, Melnikova, 2004; Gatebe et al., 2014). Optical parameters, retrieved here, are used for calculation of radiative divergence, reflected and transmitted irradiance and heating rates in cloudy atmosphere, that agree with previous observational data.

  5. MARS15 Simulation of Radiation Environment at the ESS Linac

    Mokhov, N. V. [Fermilab; Eidelman, Yu. I. [Euclid Techlabs, Solon; Rakhno, I. L. [Fermilab; Tchelidze, L. [ESS, Lund; Tropin, I. S. [Fermilab

    2016-12-01

    Comprehensive studies with the MARS15(2016) Monte-Carlo code are described on evaluation of prompt and residual radiation levels induced by nominal and accidental beam losses in the 5-MW, 2-GeV European Spallation Source (ESS) Linac. These are to provide a basis for radiation shielding design verification through the accelerator complex. The calculation model is based on the latest engineering design and includes a sophisticated algorithm for particle tracking in the machine RF cavities as well as a well-established model of the beam loss. Substantial efforts were put in solving the deep-penetration problem for the thick shielding around the tunnel with numerous complex penetrations. It allowed us to study in detail not only the prompt dose, but also component and air activation, radiation loads on the soil outside the tunnel, and skyshine studies for the complicated 3-D surface above the machine. Among the other things, the newest features in MARS15 (2016), such as a ROOT-based beamline builder and a TENDL-based event generator for nuclear interactions below 100 MeV, were very useful in this challenging application

  6. Improved simulation of Antarctic sea ice due to the radiative effects of falling snow

    Li, J.-L. F.; Richardson, Mark; Hong, Yulan; Lee, Wei-Liang; Wang, Yi-Hui; Yu, Jia-Yuh; Fetzer, Eric; Stephens, Graeme; Liu, Yinghui

    2017-08-01

    Southern Ocean sea-ice cover exerts critical control on local albedo and Antarctic precipitation, but simulated Antarctic sea-ice concentration commonly disagrees with observations. Here we show that the radiative effects of precipitating ice (falling snow) contribute substantially to this discrepancy. Many models exclude these radiative effects, so they underestimate both shortwave albedo and downward longwave radiation. Using two simulations with the climate model CESM1, we show that including falling-snow radiative effects improves the simulations relative to cloud properties from CloudSat-CALIPSO, radiation from CERES-EBAF and sea-ice concentration from passive microwave sensors. From 50-70°S, the simulated sea-ice-area bias is reduced by 2.12 × 106 km2 (55%) in winter and by 1.17 × 106 km2 (39%) in summer, mainly because increased wintertime longwave heating restricts sea-ice growth and so reduces summer albedo. Improved Antarctic sea-ice simulations will increase confidence in projected Antarctic sea level contributions and changes in global warming driven by long-term changes in Southern Ocean feedbacks.

  7. Simulation of SANS signal due to radiation damage in Fe

    Yu, G.; Schaublin, R.; Spatig, P.; Fikar, J.; Baluc, N.

    2007-01-01

    Full text of publication follows: A wide number of irradiation-induced defects in Fe-base materials (e.g. RAFM steels) have sizes in the range about 0.5 to 1 nm, which are expected to contribute to the irradiation-induced hardening and/or embrittlement phenomena. These defects are at the limit in spatial resolution of transmission electron microscopy (TEM), but they can be investigated using the small angle neutron scattering (SANS) technique, at least in terms of number density and size distribution. Determination of the type of defects (small dislocation loops, interstitials or vacancy clusters, precipitates and cavities, like voids or helium bubbles) is not straightforward. In order to analyze the type of nanometer-sized irradiation-induced defects in Fe-base materials Molecular Dynamics (MD) simulations of various distributions of different types irradiation-induced defects have been performed. The defects investigated consisted in dislocation loops with sizes of 0.5, 1.0 and 2.0 nm and 1/2 a 0 , 1/2 a 0 and a 0 Burgers vectors, cavities, like voids and helium bubbles, with sizes of 0.5, 1.0 and 2.0 nm, MD simulations of atomic displacement cascades were performed using MD samples with a size of 18 x 18 x 18 nm 3 at 10, 300 and 523 K, for PKA energies of 1, 3, 7 and 10 keV. Simulation of the corresponding nuclear SANS signal was performed using the Electron Microscopy Software (EMS) code that was originally designed to simulate TEM images and diffraction patterns and that was modified to simulate the SANS signal. Results of such simulations in pure Fe have been compared to experimental SANS measurements and TEM observations of irradiation-induced defects in Fe-base materials. (authors)

  8. Planar radiative shock experiments and their comparison to simulations

    Reighard, A. B.; Drake, R. P.; Mucino, J. E.; Knauer, J. P.; Busquet, M.

    2007-01-01

    Recent experiments have obtained radiographic data from shock waves driven at >100 km/s in xenon gas, and Thomson scattering data from similar experiments using argon gas. Presented here is a review of these experiments, followed by an outline of the discrepancies between the data and the results of one-dimensional simulations. Simulations using procedures that work well for similar but nonradiative experiments show inconsistencies between the measured position of the interface of the beryllium and xenon and the calculated position for these experiments. Sources of the discrepancy are explored

  9. nIFTy galaxy cluster simulations II: radiative models

    Sembolini, F

    2016-04-01

    Full Text Available Valerio 2, I-34127 Trieste, Italy 12Physics Department, University of the Western Cape, Cape Town 7535, Sotuh Africa 13Physics Department, University of Western Cape, Bellville, Cape Town 7535, South Africa 14South African Astronomical Observatory, PO Box...IFTy cluster comparison project (Sembolini et al., 2015): a study of the latest state-of- the-art hydrodynamical codes using simulated galaxy clusters as a testbed for theories of galaxy formation. Simulations are indis- pensable tools in the interpretation...

  10. Simulation of Radiation Heat Transfer in a VAR Furnace Using an Electrical Resistance Network

    Ballantyne, A. Stewart

    The use of electrical resistance networks to simulate heat transfer is a well known analytical technique that greatly simplifies the solution of radiation heat transfer problems. In a VAR furnace, radiative heat transfer occurs between the ingot, electrode, and crucible wall; and the arc when the latter is present during melting. To explore the relative heat exchange between these elements, a resistive network model was developed to simulate the heat exchange between the electrode, ingot, and crucible with and without the presence of an arc. This model was then combined with an ingot model to simulate the VAR process and permit a comparison between calculated and observed results during steady state melting. Results from simulations of a variety of alloys of different sizes have demonstrated the validity of the model. Subsequent simulations demonstrate the application of the model to the optimization of both steady state and hot top melt practices, and raises questions concerning heat flux assumptions at the ingot top surface.

  11. Contribution to the modelling and analysis of logistics system performance by Petri nets and simulation models: Application in a supply chain

    Azougagh, Yassine; Benhida, Khalid; Elfezazi, Said

    2016-02-01

    In this paper, the focus is on studying the performance of complex systems in a supply chain context by developing a structured modelling approach based on the methodology ASDI (Analysis, Specification, Design and Implementation) by combining the modelling by Petri nets and simulation using ARENA. The linear approach typically followed in conducting of this kind of problems has to cope with a difficulty of modelling due to the complexity and the number of parameters of concern. Therefore, the approach used in this work is able to structure modelling a way to cover all aspects of the performance study. The modelling structured approach is first introduced before being applied to the case of an industrial system in the field of phosphate. Results of the performance indicators obtained from the models developed, permitted to test the behaviour and fluctuations of this system and to develop improved models of the current situation. In addition, in this paper, it was shown how Arena software can be adopted to simulate complex systems effectively. The method in this research can be applied to investigate various improvements scenarios and their consequences before implementing them in reality.

  12. Comparison of scattering experiments using synchrotron radiation with Monte Carlo simulations using Geant4

    Gerlach, M.; Krumrey, M.; Cibik, L.; Mueller, P.; Ulm, G.

    2009-01-01

    Monte Carlo techniques are powerful tools to simulate the interaction of electromagnetic radiation with matter. One of the most widespread simulation program packages is Geant4. Almost all physical interaction processes can be included. However, it is not evident what accuracy can be obtained by a simulation. In this work, results of scattering experiments using monochromatized synchrotron radiation in the X-ray regime are quantitatively compared to the results of simulations using Geant4. Experiments were performed for various scattering foils made of different materials such as copper and gold. For energy-dispersive measurements of the scattered radiation, a cadmium telluride detector was used. The detector was fully characterized and calibrated with calculable undispersed as well as monochromatized synchrotron radiation. The obtained quantum efficiency and the response functions are in very good agreement with the corresponding Geant4 simulations. At the electron storage ring BESSY II the number of incident photons in the scattering experiments was measured with a photodiode that had been calibrated against a cryogenic radiometer, so that a direct comparison of scattering experiments with Monte Carlo simulations using Geant4 was possible. It was shown that Geant4 describes the photoeffect, including fluorescence as well as the Compton and Rayleigh scattering, with high accuracy, resulting in a deviation of typically less than 20%. Even polarization effects are widely covered by Geant4, and for Doppler broadening of Compton-scattered radiation the extension G4LECS can be included, but the fact that both features cannot be combined is a limitation. For most polarization-dependent simulations, good agreement with the experimental results was found, except for some orientations where Rayleigh scattering was overestimated in the simulation.

  13. Comparison of scattering experiments using synchrotron radiation with Monte Carlo simulations using Geant4

    Gerlach, M.; Krumrey, M.; Cibik, L.; Müller, P.; Ulm, G.

    2009-09-01

    Monte Carlo techniques are powerful tools to simulate the interaction of electromagnetic radiation with matter. One of the most widespread simulation program packages is Geant4. Almost all physical interaction processes can be included. However, it is not evident what accuracy can be obtained by a simulation. In this work, results of scattering experiments using monochromatized synchrotron radiation in the X-ray regime are quantitatively compared to the results of simulations using Geant4. Experiments were performed for various scattering foils made of different materials such as copper and gold. For energy-dispersive measurements of the scattered radiation, a cadmium telluride detector was used. The detector was fully characterized and calibrated with calculable undispersed as well as monochromatized synchrotron radiation. The obtained quantum efficiency and the response functions are in very good agreement with the corresponding Geant4 simulations. At the electron storage ring BESSY II the number of incident photons in the scattering experiments was measured with a photodiode that had been calibrated against a cryogenic radiometer, so that a direct comparison of scattering experiments with Monte Carlo simulations using Geant4 was possible. It was shown that Geant4 describes the photoeffect, including fluorescence as well as the Compton and Rayleigh scattering, with high accuracy, resulting in a deviation of typically less than 20%. Even polarization effects are widely covered by Geant4, and for Doppler broadening of Compton-scattered radiation the extension G4LECS can be included, but the fact that both features cannot be combined is a limitation. For most polarization-dependent simulations, good agreement with the experimental results was found, except for some orientations where Rayleigh scattering was overestimated in the simulation.

  14. Comparison of scattering experiments using synchrotron radiation with Monte Carlo simulations using Geant4

    Gerlach, M. [Physikalisch-Technische Bundesanstalt, Abbestr. 2-12, 10587 Berlin (Germany); Krumrey, M. [Physikalisch-Technische Bundesanstalt, Abbestr. 2-12, 10587 Berlin (Germany)], E-mail: Michael.Krumrey@ptb.de; Cibik, L.; Mueller, P.; Ulm, G. [Physikalisch-Technische Bundesanstalt, Abbestr. 2-12, 10587 Berlin (Germany)

    2009-09-11

    Monte Carlo techniques are powerful tools to simulate the interaction of electromagnetic radiation with matter. One of the most widespread simulation program packages is Geant4. Almost all physical interaction processes can be included. However, it is not evident what accuracy can be obtained by a simulation. In this work, results of scattering experiments using monochromatized synchrotron radiation in the X-ray regime are quantitatively compared to the results of simulations using Geant4. Experiments were performed for various scattering foils made of different materials such as copper and gold. For energy-dispersive measurements of the scattered radiation, a cadmium telluride detector was used. The detector was fully characterized and calibrated with calculable undispersed as well as monochromatized synchrotron radiation. The obtained quantum efficiency and the response functions are in very good agreement with the corresponding Geant4 simulations. At the electron storage ring BESSY II the number of incident photons in the scattering experiments was measured with a photodiode that had been calibrated against a cryogenic radiometer, so that a direct comparison of scattering experiments with Monte Carlo simulations using Geant4 was possible. It was shown that Geant4 describes the photoeffect, including fluorescence as well as the Compton and Rayleigh scattering, with high accuracy, resulting in a deviation of typically less than 20%. Even polarization effects are widely covered by Geant4, and for Doppler broadening of Compton-scattered radiation the extension G4LECS can be included, but the fact that both features cannot be combined is a limitation. For most polarization-dependent simulations, good agreement with the experimental results was found, except for some orientations where Rayleigh scattering was overestimated in the simulation.

  15. Numerical simulation and experimental research of the integrated high-power LED radiator

    Xiang, J. H.; Zhang, C. L.; Gan, Z. J.; Zhou, C.; Chen, C. G.; Chen, S.

    2017-01-01

    The thermal management has become an urgent problem to be solved with the increasing power and the improving integration of the LED (light emitting diode) chip. In order to eliminate the contact resistance of the radiator, this paper presented an integrated high-power LED radiator based on phase-change heat transfer, which realized the seamless connection between the vapor chamber and the cooling fins. The radiator was optimized by combining the numerical simulation and the experimental research. The effects of the chamber diameter and the parameters of fin on the heat dissipation performance were analyzed. The numerical simulation results were compared with the measured values by experiment. The results showed that the fin thickness, the fin number, the fin height and the chamber diameter were the factors which affected the performance of radiator from primary to secondary.

  16. Optical roughness BRDF model for reverse Monte Carlo simulation of real material thermal radiation transfer.

    Su, Peiran; Eri, Qitai; Wang, Qiang

    2014-04-10

    Optical roughness was introduced into the bidirectional reflectance distribution function (BRDF) model to simulate the reflectance characteristics of thermal radiation. The optical roughness BRDF model stemmed from the influence of surface roughness and wavelength on the ray reflectance calculation. This model was adopted to simulate real metal emissivity. The reverse Monte Carlo method was used to display the distribution of reflectance rays. The numerical simulations showed that the optical roughness BRDF model can calculate the wavelength effect on emissivity and simulate the real metal emissivity variance with incidence angles.

  17. Simulating of spectrum and polarization characteristics of ultrarelativistic - electron coherent radiation in a diamond crystal

    Truten', V.I.

    2000-01-01

    On the base of the computer simulation method it is shown that new maxima of ultrarelativistic electron radiation spectrum in aligned crystals may appear in a low-frequency region together with the ordinary coherent maxima. The appearance of these maxima is the result of the high-index-crystal-plane effect. These maxima manifest themselves in spectral as well as in polarization features of radiation [ru

  18. Measurements and TCAD Simulations of Bulk and Surface Radiation Damage Effects

    F. Moscatelli; G. M. Bilei; A. Morozzi; G.-F. Dalla Betta; R. Mendicino; M. Boscardin; N. Zorzi; L. Servoli; P. Maccagnani

    2016-01-01

    In this work we propose the application of a radiation damage model based on the introduction of deep level traps/recombination centers suitable for device level numerical simulation of radiation detectors at very high fluences (e.g. 1÷2×1016 1-MeV equivalent neutrons per square centimeter) combined with a surface damage model developed by using experimental parameters extracted from measurements from gamma irradiated p-type dedicated test structures.

  19. Solar radiation data - statistical analysis and simulation models

    Mustacchi, C; Cena, V; Rocchi, M; Haghigat, F

    1984-01-01

    The activities consisted in collecting meteorological data on magnetic tape for ten european locations (with latitudes ranging from 42/sup 0/ to 56/sup 0/ N), analysing the multi-year sequences, developing mathematical models to generate synthetic sequences having the same statistical properties of the original data sets, and producing one or more Short Reference Years (SRY's) for each location. The meteorological parameters examinated were (for all the locations) global + diffuse radiation on horizontal surface, dry bulb temperature, sunshine duration. For some of the locations additional parameters were available, namely, global, beam and diffuse radiation on surfaces other than horizontal, wet bulb temperature, wind velocity, cloud type, cloud cover. The statistical properties investigated were mean, variance, autocorrelation, crosscorrelation with selected parameters, probability density function. For all the meteorological parameters, various mathematical models were built: linear regression, stochastic models of the AR and the DAR type. In each case, the model with the best statistical behaviour was selected for the production of a SRY for the relevant parameter/location.

  20. Simulation of beta radiator handling procedures in nuclear medicine by means of a movable hand phantom.

    Blunck, Ch; Becker, F; Urban, M

    2011-03-01

    In nuclear medicine therapies, people working with beta radiators such as (90)Y may be exposed to non-negligible partial body doses. For radiation protection, it is important to know the characteristics of the radiation field and possible dose exposures at relevant positions in the working area. Besides extensive measurements, simulations can provide these data. For this purpose, a movable hand phantom for Monte Carlo simulations was developed. Specific beta radiator handling scenarios can be modelled interactively with forward kinematics or automatically with an inverse kinematics procedure. As a first investigation, the dose distribution on a medical doctor's hand injecting a (90)Y solution was measured and simulated with the phantom. Modelling was done with the interactive method based on five consecutive frames from a video recorded during the injection. Owing to the use of only one camera, not each detail of the radiation scenario is visible in the video. In spite of systematic uncertainties, the measured and simulated dose values are in good agreement.

  1. Quality assurance for computed-tomography simulators and the computed-tomography-simulation process: Report of the AAPM Radiation Therapy Committee Task Group No. 66

    Mutic, Sasa; Palta, Jatinder R.; Butker, Elizabeth K.; Das, Indra J.; Huq, M. Saiful; Loo, Leh-Nien Dick; Salter, Bill J.; McCollough, Cynthia H.; Van Dyk, Jacob

    2003-01-01

    This document presents recommendations of the American Association of Physicists in Medicine (AAPM) for quality assurance of computed-tomography- (CT) simulators and CT-simulation process. This report was prepared by Task Group No. 66 of the AAPM Radiation Therapy Committee. It was approved by the Radiation Therapy Committee and by the AAPM Science Council

  2. Backscattered radiation into a transmission ionization chamber: Measurement and Monte Carlo simulation

    Yoshizumi, Maira T.; Yoriyaz, Helio; Caldas, Linda V.E.

    2010-01-01

    Backscattered radiation (BSR) from field-defining collimators can affect the response of a monitor chamber in X-radiation fields. This contribution must be considered since this kind of chamber is used to monitor the equipment response. In this work, the dependence of a transmission ionization chamber response on the aperture diameter of the collimators was studied experimentally and using a Monte Carlo (MC) technique. According to the results, the BSR increases the chamber response of over 4.0% in the case of a totally closed collimator and 50 kV energy beam, using both techniques. The results from Monte Carlo simulation confirm the validity of the simulated geometry.

  3. Computer simulations of radiation damage in protein crystals; Simulationsrechnungen zu Strahlenschaeden an Proteinkristallen

    Zehnder, M

    2007-03-15

    The achievable resolution and the quality of the dataset of an intensity data collection for structure analysis of protein crystals with X-rays is limited among other factors by radiation damage. The aim of this work is to obtain a better quantitative understanding of the radiation damage process in proteins. Since radiation damage is unavoidable it was intended to look for the optimum ratio between elastically scattered intensity and radiation damage. Using a Monte Carlo algorithm physical processes after an inelastic photon interaction are studied. The main radiation damage consists of ionizations of the atoms through the electron cascade following any inelastic photon interaction. Results of the method introduced in this investigation and results of an earlier theoretical studies of the influence of Auger-electron transport in diamond are in a good agreement. The dependence of the radiation damage as a function of the energy of the incident photon was studied by computer-aided simulations. The optimum energy range for diffraction experiments on the protein myoglobin is 10-40 keV. Studies of radiation damage as a function of crystal volume and shape revealed that very small plate or rod shaped crystals suffer less damage than crystals formed like a cube with the same volume. Furthermore the influence of a few heavy atoms in the protein molecule on radiation damage was examined. Already two iron atoms in the unit cell of myoglobin increase radiation damage significantly. (orig.)

  4. Effect of the Absorbed Photosynthetically Active Radiation Estimation Error on Net Primary Production Estimation - A Study with MODIS FPAR and TOMS Ultraviolet Reflective Products

    Kobayashi, H.; Matsunaga, T.; Hoyano, A.

    2002-01-01

    Absorbed photosynthetically active radiation (APAR), which is defined as downward solar radiation in 400-700 nm absorbed by vegetation, is one of the significant variables for Net Primary Production (NPP) estimation from satellite data. Toward the reduction of the uncertainties in the global NPP estimation, it is necessary to clarify the APAR accuracy. In this paper, first we proposed the improved PAR estimation method based on Eck and Dye's method in which the ultraviolet (UV) reflectivity data derived from Total Ozone Mapping Spectrometer (TOMS) at the top of atmosphere were used for clouds transmittance estimation. The proposed method considered the variable effects of land surface UV reflectivity on the satellite-observed UV data. Monthly mean PAR comparisons between satellite-derived and ground-based data at various meteorological stations in Japan indicated that the improved PAR estimation method reduced the bias errors in the summer season. Assuming the relative error of the fraction of PAR (FPAR) derived from Moderate Resolution Imaging Spectroradiometer (MODIS) to be 10%, we estimated APAR relative errors to be 10-15%. Annual NPP is calculated using APAR derived from MODIS/ FPAR and the improved PAR estimation method. It is shown that random and bias errors of annual NPP in a 1 km resolution pixel are less than 4% and 6% respectively. The APAR bias errors due to the PAR bias errors also affect the estimated total NPP. We estimated the most probable total annual NPP in Japan by subtracting the bias PAR errors. It amounts about 248 MtC/yr. Using the improved PAR estimation method, and Eck and Dye's method, total annual NPP is 4% and 9% difference from most probable value respectively. The previous intercomparison study among using fifteen NPP models4) showed that global NPP estimations among NPP models are 44.4-66.3 GtC/yr (coefficient of variation = 14%). Hence we conclude that the NPP estimation uncertainty due to APAR estimation error is small

  5. Applicability of Daily Solar Radiation Estimated by Mountain Microclimate Simulation Model (MT-CLIM) in Korea

    Shim, K.M.; Kim, Y.S.; Lee, D.B.; Kang, K.K.; So, K.H.

    2012-01-01

    Accuracy of daily solar radiation estimated from a Mountain Microclimate Simulation Model (MT-CLIM) was assessed for seven observation sites with complex topography in Uiseong County. The coefficient of determination () between the observed and the estimated daily solar radiation was 0.52 for 7 sites for the study period from 1 August to 30 September 2009. Overall, the MT-CLIM overestimated the solar radiation with root mean square error (RMSE) of which is about 25% of the mean daily solar radiation () for the study period. Considering that the pyranometer's tolerance is of standard sensor, the RMSE of MT-CLIM was too large to accept for a direct application for agricultural sector. The reliability of solar radiation estimated by MT-CLIM must be improved by considering additional ways such as using a topography correction coefficient

  6. CST simulations of THz Smith–Purcell radiation from a lamellar grating with vacuum gaps

    Lekomtsev, K.; Karataev, P.; Tishchenko, A.A.; Urakawa, J.

    2015-01-01

    Smith–Purcell radiation (SPR) from a lamellar grating with vacuum gaps was calculated using Computer Simulation Technology (CST) Particle In Cell (PIC) solver. The shapes of the radiation distributions were compared with those of Resonant Diffraction Radiation theory. Study of calculation domain meshing was performed. Influence of a transverse bunch size on the calculation accuracy and an SPR intensity distribution was investigated. Dependencies of the SPR yield on Lorentz factor and grating strip depth were calculated and compared with previously reported theoretical and experimental studies

  7. Simulation-based model checking approach to cell fate specification during Caenorhabditis elegans vulval development by hybrid functional Petri net with extension

    Ueno Kazuko

    2009-04-01

    Full Text Available Abstract Background Model checking approaches were applied to biological pathway validations around 2003. Recently, Fisher et al. have proved the importance of model checking approach by inferring new regulation of signaling crosstalk in C. elegans and confirming the regulation with biological experiments. They took a discrete and state-based approach to explore all possible states of the system underlying vulval precursor cell (VPC fate specification for desired properties. However, since both discrete and continuous features appear to be an indispensable part of biological processes, it is more appropriate to use quantitative models to capture the dynamics of biological systems. Our key motivation of this paper is to establish a quantitative methodology to model and analyze in silico models incorporating the use of model checking approach. Results A novel method of modeling and simulating biological systems with the use of model checking approach is proposed based on hybrid functional Petri net with extension (HFPNe as the framework dealing with both discrete and continuous events. Firstly, we construct a quantitative VPC fate model with 1761 components by using HFPNe. Secondly, we employ two major biological fate determination rules – Rule I and Rule II – to VPC fate model. We then conduct 10,000 simulations for each of 48 sets of different genotypes, investigate variations of cell fate patterns under each genotype, and validate the two rules by comparing three simulation targets consisting of fate patterns obtained from in silico and in vivo experiments. In particular, an evaluation was successfully done by using our VPC fate model to investigate one target derived from biological experiments involving hybrid lineage observations. However, the understandings of hybrid lineages are hard to make on a discrete model because the hybrid lineage occurs when the system comes close to certain thresholds as discussed by Sternberg and Horvitz in

  8. Numerical simulation of variance of solar radiation and its influence on wheat growth

    Zhang, Xuefen; Wang, Chunyi; Du, Zixuan; Zhai, Wei

    2007-09-01

    The growth of crops is directly related to solar radiation whose variances influence the photosynthesis of crops and the growth momentum thereof. This dissertation has Zhengzhou, which located in the Huanghuai Farmland Ecological System of China, as an example to analyze the rules of variances of total solar radiation, direct radiation and diffusive radiation. With the help of linear trend fitting, it is identified that total radiation (TR) drops as a whole at a rate of 1.6482J/m2. Such drop has been particularly apparent in recent years with a period of 7 to 16 years; diffusive radiation (DF) tends to increase at a rate of 15.149 J/m2 with a period of 20 years; direct radiation (DR) tends to drop at a rate of 15.843 J/m2 without apparent period. The total radiation has been on the decrease ever since 1980 during the growth period of wheat. Having modified relevant Parameter in the Carbon and Nitrogen Biogeochemistry in Agroecosystems Model (DNDC) model and simulated the influence of solar radiation variances on the development phase, leaf area index (LAI), grain weight, etc during the growth period of wheat, it is found that solar radiation is in positive proportion to LAI and grain weight (GRNWT) but not apparently related to development phase (DP). The change of total radiation delays the maximization of wheat LAI, reduces wheat LAI before winter but has no apparent effect in winter and decreases wheat LAI from jointing period to filling period; it has no apparent influence on grain formation at the early stage of grain formation, slows down the weight increase of grains during the filling period and accelerates the weight increase of grains at the end of filling period. Variance of radiations does not affect the DP of wheat much.

  9. Sudden Exposure to Solar UV-B Radiation Reduces Net CO2 Uptake and Photosystem I Efficiency in Shade-Acclimated Tropical Tree Seedlings1

    Krause, G. Heinrich; Grube, Esther; Virgo, Aurelio; Winter, Klaus

    2003-01-01

    Tree seedlings developing in the understory of the tropical forest have to endure short periods of high-light stress when tree-fall gaps are formed, and direct solar radiation, including substantial UV light, reaches the leaves. In experiments simulating the opening of a tree-fall gap, the response of photosynthesis in leaves of shade-acclimated seedlings (Anacardium excelsum, Virola surinamensis, and Calophyllum longifolium) to exposure to direct sunlight (for 20–50 min) was investigated in Panama (9°N). To assess the effects of solar UV-B radiation (280–320 nm), the sunlight was filtered through plastic films that selectively absorbed UV-B or transmitted the complete spectrum. The results document a strong inhibition of CO2 assimilation by sun exposure. Light-limited and light-saturated rates of photosynthetic CO2 uptake by the leaves were affected, which apparently occurred independently of a simultaneous inhibition of potential photosystem (PS) II efficiency. The ambient UV-B light substantially contributed to these effects. The photochemical capacity of PSI, measured as absorbance change at 810 nm in saturating far-red light, was not significantly affected by sun exposure of the seedlings. However, a decrease in the efficiency of P700 photooxidation by far-red light was observed, which was strongly promoted by solar UV-B radiation. The decrease in PSI efficiency may result from enhanced charge recombination in the reaction center, which might represent an incipient inactivation of PSI, but contributes to thermal dissipation of excessive light energy and thereby to photoprotection. PMID:12586898

  10. Integrated simulation of continuous-scale and discrete-scale radiative transfer in metal foams

    Xia, Xin-Lin; Li, Yang; Sun, Chuang; Ai, Qing; Tan, He-Ping

    2018-06-01

    A novel integrated simulation of radiative transfer in metal foams is presented. It integrates the continuous-scale simulation with the direct discrete-scale simulation in a single computational domain. It relies on the coupling of the real discrete-scale foam geometry with the equivalent continuous-scale medium through a specially defined scale-coupled zone. This zone holds continuous but nonhomogeneous volumetric radiative properties. The scale-coupled approach is compared to the traditional continuous-scale approach using volumetric radiative properties in the equivalent participating medium and to the direct discrete-scale approach employing the real 3D foam geometry obtained by computed tomography. All the analyses are based on geometrical optics. The Monte Carlo ray-tracing procedure is used for computations of the absorbed radiative fluxes and the apparent radiative behaviors of metal foams. The results obtained by the three approaches are in tenable agreement. The scale-coupled approach is fully validated in calculating the apparent radiative behaviors of metal foams composed of very absorbing to very reflective struts and that composed of very rough to very smooth struts. This new approach leads to a reduction in computational time by approximately one order of magnitude compared to the direct discrete-scale approach. Meanwhile, it can offer information on the local geometry-dependent feature and at the same time the equivalent feature in an integrated simulation. This new approach is promising to combine the advantages of the continuous-scale approach (rapid calculations) and direct discrete-scale approach (accurate prediction of local radiative quantities).

  11. Flux canceling in three-dimensional radiative magnetohydrodynamic simulations

    Thaler, Irina; Spruit, H. C.

    2017-05-01

    We aim to study the processes involved in the disappearance of magnetic flux between regions of opposite polarity on the solar surface using realistic three-dimensional (3D) magnetohydrodynamic (MHD) simulations. "Retraction" below the surface driven by magnetic forces is found to be a very effective mechanism of flux canceling of opposite polarities. The speed at which flux disappears increases strongly with initial mean flux density. In agreement with existing inferences from observations we suggest that this is a key process of flux disappearance within active complexes. Intrinsic kG strength concentrations connect the surface to deeper layers by magnetic forces, and therefore the influence of deeper layers on the flux canceling process is studied. We do this by comparing simulations extending to different depths. For average flux densities of 50 G, and on length scales on the order of 3 Mm in the horizontal and 10 Mm in depth, deeper layers appear to have only a mild influence on the effective rate of diffusion.

  12. Neutrino radiation-hydrodynamics. General relativistic versus multidimensional supernova simulations

    Liebendoerfer, Matthias; Fischer, Tobias; Hempel, Matthias

    2010-01-01

    Recently, simulations of the collapse of massive stars showed that selected models of the QCD phase transitions to deconfined quarks during the early postbounce phase can trigger the supernova explosion that has been searched for over many years in spherically symmetric supernova models. Using sophisticated general relativistic Boltzmann neutrino transport, it was found that a characteristic neutrino signature is emitted that permits to falsify or identify this scenario in the next Galactic supernova event. On the other hand, more refined observations of past supernovae and progressing theoretical research in different supernova groups demonstrated that the effects of multidimensional fluid instabilities cannot be neglected in global models of the explosions of massive stars. We point to different efforts where neutrino transport and general relativistic effects are combined with multidimensional fluid instabilities in supernovae. With those, it will be possible to explore the gravitational wave emission as a potential second characteristic observable of the presence of quark matter in new-born neutron stars. (author)

  13. Photon radiation damage simulations in CZT semiconducting detectors

    Leyva, A.; Pinnera, I.; Cruz, C.; Abreu, Y.; Dona, O.; Diaz, A.

    2009-01-01

    The use of semiconducting devices based on CZT as X and gamma rays detectors has been extended notably in the last decade thanks to their numerous advantages. The medical imagenology is one of the fields where these detectors have been successfully introduced, for example in positron emission tomography (PET). A typical CZT detector employed PET application was studied applying the Monte Carlo statistical method. All structural and geometric characteristics of the detector as well as the different photon energies usually used in the mentioned applications were considered in the simulations. Taking into account the Oen-Cahn-Holmes classical approach, the effective atomic displacement cross-sections and the number of displacements per atoms were calculated for all atom species and considered photon energies

  14. Numerical simulations of radiation hydrodynamics and modeling of high temperature hohlraum cavities

    Gupta, N.K.; Godwal, B.K.

    2003-10-01

    A summary of our efforts towards the validation of radiation hydrodynamics and opacity models are presented. Effects of various parameters on the radiation temperature inside an inertial confinement fusion (ICF) hohlraum, the effects of non-local thermodynamic equilibrium conditions on emission and absorption, and the hydrodynamics of aluminium and gold foils driven by radiation are studied. LTE and non-LTE predictions for emitted radiation are compared with the experimental results and it is seen that non-LTE simulations show a marked improvement over LTE results. It is shown that the mixing of two high Z materials can lead to an enhancement in the Rosseland mean. An experimental study of soft x-ray emission from laser-irradiated Au-Cu mix-Z targets confirmed these predictions. It is seen that only multi group non-LTE radiation transport is able to explain experimentally observed features in the conversion efficiency of laser light to x-rays. One group radiation transport under predicts the radiation temperature. It is shown that erroneous results can be obtained if the space mesh in the hohlraum wall is not fine enough. Hydrodynamics of a wedge shaped aluminium foil driven by the hohlraum radiation is also presented and results are compared with NOVA laser experiments. Laser driven shock wave EOS and gold hohlraum experiments carried out at CAT are analyzed and they confirmed our theoretical estimates. (author)

  15. A multileaf collimator phantom for the quality assurance of radiation therapy planning systems and CT simulators

    McNiven, Andrea; Kron, Tomas; Van Dyk, Jake

    2004-01-01

    Purpose: The evolution of three-dimensional conformal radiation treatment has led to the use of multileaf collimators (MLCs) in intensity-modulated radiation therapy (IMRT) and other treatment techniques to increase the conformity of the dose distribution. A new quality assurance (QA) phantom has been designed to check the handling of MLC settings in treatment planning and delivery. Methods and materials: The phantom consists of a Perspex block with stepped edges that can be rotated in all planes. The design allows for the assessment of several MLC and micro-MLC types from various manufacturers, and is therefore applicable to most radiation therapy institutions employing MLCs. The phantom is computed tomography (CT) scanned as is a patient, and QA assessments can be made of field edge display for a variety of shapes and orientations on both radiation treatment planning systems (RTPS) and computed tomography simulators. Results: The dimensions of the phantom were verified to be physically correct within an uncertainty range of 0-0.7 mm. Errors in leaf position larger than 1 mm were easily identified by multiple observers. Conclusions: The MLC geometry phantom is a useful tool in the QA of radiation therapy with application to RTPS, CT simulators, and virtual simulation packages with MLC display capabilities

  16. PUMN: part I of the WINERY radiation damage computer simulation system

    Kuspa, J.P.; Edwards, D.R.; Tsoulfanidis, N.

    1976-01-01

    Results of computer work to simulate the response of crystalline materials to radiation are presented. To organize this and future work into a long range program of investigation, the WINERY Radiation Damage Computer Simulation System is proposed. The WINERY system is designed to solve the entire radiation damage problem from the incident radiation to the property changes which occur in the material, using a set of interrelated computer programs. One portion of the system, the PUMN program, has been used to obtain important radiation damage results with Fe 3 Al crystal. PUMN simulates the response of the atoms in a crystal to a knock-on atom. It yields the damage configuration of the crystal by considering the dynamic interaction of all the atoms of the computational cell, up to 1000 atoms. The PUMN program provides the WINERY system with results for the number of displacements, N/sub d/, due to knock-on atoms with various energies. The values of N/sub d/ for Fe 3 Al were obtained at two different energies, 100 and 500 eV, for a variety of initial directions. These values are to be used to form a table of results for use in WINERY

  17. Step-by-Step Simulation of Radiation Chemistry Using Green Functions for Diffusion-Influenced Reactions

    Plante, Ianik; Cucinotta, Francis A.

    2011-01-01

    Radiolytic species are formed approximately 1 ps after the passage of ionizing radiation through matter. After their formation, they diffuse and chemically react with other radiolytic species and neighboring biological molecules, leading to various oxidative damage. Therefore, the simulation of radiation chemistry is of considerable importance to understand how radiolytic species damage biological molecules [1]. The step-by-step simulation of chemical reactions is difficult, because the radiolytic species are distributed non-homogeneously in the medium. Consequently, computational approaches based on Green functions for diffusion-influenced reactions should be used [2]. Recently, Green functions for more complex type of reactions have been published [3-4]. We have developed exact random variate generators of these Green functions [5], which will allow us to use them in radiation chemistry codes. Moreover, simulating chemistry using the Green functions is which is computationally very demanding, because the probabilities of reactions between each pair of particles should be evaluated at each timestep [2]. This kind of problem is well adapted for General Purpose Graphic Processing Units (GPGPU), which can handle a large number of similar calculations simultaneously. These new developments will allow us to include more complex reactions in chemistry codes, and to improve the calculation time. This code should be of importance to link radiation track structure simulations and DNA damage models.

  18. Topical tacrolimus in combination with simulated solar radiation does not enhance photocarcinogenesis in hairless mice

    Lerche, C.M.; Philipsen, P.A.; Poulsen, T.

    2008-01-01

    tacrolimus ointment on squamous cell carcinoma formation in hairless female C3.Cg/TifBomTac immunocompetent mice exposed to solar simulated radiation (SSR). In a first experiment, mice (n = 200) had tacrolimus applied on their dorsal skin three times weekly followed by SSR (2, 4 or 6 standard erythema doses...

  19. Simulation of African dust properties and radiative effects during the 2015 SHADOW campaign in Senegal

    Péré, J.-C.; Rivellini, L.; Crumeyrolle, S.; Chiapello, I.; Minvielle, F.; Thieuleux, F.; Choël, M.; Popovici, I.

    2018-01-01

    The aim of this work is to estimate optical and radiative properties of dust aerosols and their potential feedbacks on atmospheric properties over Western Africa for the period 20 March-28 April 2015, by using numerical simulations and different sets of remote-sensing and in-situ measurements. Comparisons of simulations made by the on-line coupled meteorological-chemistry model WRF-CHEM with MODIS, AERONET and in-situ observations result in a general agreement for the spatio-temporal variations of aerosol extinction at both local and regional scales. Simulated SSA reached elevated values between 0.88 and 0.96 along the visible/near-infrared in close agreement with AERONET inversions, suggesting the predominance of dust over Western Africa during this specific period. This predominance of dust is confirmed by in-situ measurements of the aerosol size distribution, fitting well with the aerosols size distribution simulated by WRF-CHEM. The impact of this large dust load on the radiative fluxes leads to large modifications of the shortwave and longwave radiative budget both at the ground and at the top of the atmosphere. In return, the response of the atmosphere to these dust-induced radiative changes is the alteration of the surface air temperature and wind fields, with non-negligible impact on the dust emission and transport.

  20. Simulation of pulsed-ionizing-radiation-induced errors in CMOS memory circuits

    Massengill, L.W.

    1987-01-01

    Effects of transient ionizing radiation on complementary metal-oxide-semiconductor (CMOS) memory circuits was studied by computer simulation. Simulation results have uncovered the dominant mechanism leading to information loss (upset) in dense (CMOS) circuits: rail span collapse. This effect is the catastrophic reduction in the local power supply at a RAM cell location due to the conglomerate radiation-induced photocurrents from all other RAM cells flowing through the power-supply-interconnect distribution. Rail-span collapse leads to reduced RAM cell-noise margins and can predicate upset. Results show that rail-span collapse in the dominant pulsed radiation effect in many memory circuits, preempting local circuit responses to the radiation. Several techniques to model power-supply noise, such as that arising from rail span collapse, are presented in this work. These include an analytical model for design optimization against these effects, a hierarchical computer-analysis technique for efficient power bus noise simulation in arrayed circuits, such as memories, and a complete circuit-simulation tool for noise margin analysis of circuits with arbitrary topologies

  1. Interventional Radiation Oncology (IRO): Transition of a magnetic resonance simulator to a brachytherapy suite.

    Anderson, Roberta; Armour, Elwood; Beeckler, Courtney; Briner, Valerie; Choflet, Amanda; Cox, Andrea; Fader, Amanda N; Hannah, Marie N; Hobbs, Robert; Huang, Ellen; Kiely, Marilyn; Lee, Junghoon; Morcos, Marc; McMillan, Paige E; Miller, Dave; Ng, Sook Kien; Prasad, Rashmi; Souranis, Annette; Thomsen, Robert; DeWeese, Theodore L; Viswanathan, Akila N

    2018-03-13

    As a core component of a new gynecologic cancer radiation program, we envisioned, structured, and implemented a novel Interventional Radiation Oncology (IRO) unit and magnetic resonance (MR)-brachytherapy environment in an existing MR simulator. We describe the external and internal processes required over a 6-8 month time frame to develop a clinical and research program for gynecologic brachytherapy and to successfully convert an MR simulator into an IRO unit. Support of the institution and department resulted in conversion of an MR simulator to a procedural suite. Development of the MR gynecologic brachytherapy program required novel equipment, staffing, infrastructural development, and cooperative team development with anesthetists, nurses, therapists, physicists, and physicians to ensure a safe and functional environment. Creation of a separate IRO unit permitted a novel billing structure. The creation of an MR-brachytherapy environment in an MR simulator is feasible. Developing infrastructure includes several collaborative elements. Unique to the field of radiation oncology, formalizing the space as an Interventional Radiation Oncology unit permits a sustainable financial structure. Copyright © 2018 American Brachytherapy Society. Published by Elsevier Inc. All rights reserved.

  2. Monte Carlo closure for moment-based transport schemes in general relativistic radiation hydrodynamic simulations

    Foucart, Francois

    2018-04-01

    General relativistic radiation hydrodynamic simulations are necessary to accurately model a number of astrophysical systems involving black holes and neutron stars. Photon transport plays a crucial role in radiatively dominated accretion discs, while neutrino transport is critical to core-collapse supernovae and to the modelling of electromagnetic transients and nucleosynthesis in neutron star mergers. However, evolving the full Boltzmann equations of radiative transport is extremely expensive. Here, we describe the implementation in the general relativistic SPEC code of a cheaper radiation hydrodynamic method that theoretically converges to a solution of Boltzmann's equation in the limit of infinite numerical resources. The algorithm is based on a grey two-moment scheme, in which we evolve the energy density and momentum density of the radiation. Two-moment schemes require a closure that fills in missing information about the energy spectrum and higher order moments of the radiation. Instead of the approximate analytical closure currently used in core-collapse and merger simulations, we complement the two-moment scheme with a low-accuracy Monte Carlo evolution. The Monte Carlo results can provide any or all of the missing information in the evolution of the moments, as desired by the user. As a first test of our methods, we study a set of idealized problems demonstrating that our algorithm performs significantly better than existing analytical closures. We also discuss the current limitations of our method, in particular open questions regarding the stability of the fully coupled scheme.

  3. Reduction in emittance of thermal radiator coatings caused by the accumulation of a Martian dust simulant

    Hollingsworth, D. Keith; Witte, Larry C.; Hinke, Jaime [Department of Mechanical Engineering, University of Houston, Houston, TX 77204-4006 (United States); Hurlbert, Kathryn [NASA, Johnson Space Center (United States)

    2006-12-15

    Measurements were made of the effective emittance of three types of radiator coatings as a Martian dust simulant was added to the radiator surfaces. The apparatus consisted of multiple radiator coupons on which Carbondale Red Clay dust was deposited. The coupon design employed guard heating to achieve the accuracy required for acceptable emittance calculations. The apparatus was contained in a vacuum chamber that featured a liquid-nitrogen cooled shroud that simulated the Martian sky temperature. Three high-emittance radiator coatings were tested: two while silicate paints, Z-93P and NS-43G, and a silver Teflon film. Radiator temperatures ranged from 250 to 350K with sky temperatures from 185 to 248K. As dust was added to the radiator surfaces, the effective emittance of all three coatings decreased from initial values near 0.9 to a value near 0.4. A low-emittance control surface, polished aluminum, demonstrated a rise in effective emittance for thin dust layers, and then a decline as the dust layer thickened. This behavior is attributed to the conductive resistance caused by the dust layer. (author)

  4. Monte Carlo radiative transfer simulation of a cavity solar reactor for the reduction of cerium oxide

    Villafan-Vidales, H.I.; Arancibia-Bulnes, C.A.; Dehesa-Carrasco, U. [Centro de Investigacion en Energia, Universidad Nacional Autonoma de Mexico, Privada Xochicalco s/n, Col. Centro, A.P. 34, Temixco, Morelos 62580 (Mexico); Romero-Paredes, H. [Departamento de Ingenieria de Procesos e Hidraulica, Universidad Autonoma Metropolitana-Iztapalapa, Av. San Rafael Atlixco No.186, Col. Vicentina, A.P. 55-534, Mexico D.F 09340 (Mexico)

    2009-01-15

    Radiative heat transfer in a solar thermochemical reactor for the thermal reduction of cerium oxide is simulated with the Monte Carlo method. The directional characteristics and the power distribution of the concentrated solar radiation that enters the cavity is obtained by carrying out a Monte Carlo ray tracing of a paraboloidal concentrator. It is considered that the reactor contains a gas/particle suspension directly exposed to concentrated solar radiation. The suspension is treated as a non-isothermal, non-gray, absorbing, emitting, and anisotropically scattering medium. The transport coefficients of the particles are obtained from Mie-scattering theory by using the optical properties of cerium oxide. From the simulations, the aperture radius and the particle concentration were optimized to match the characteristics of the considered concentrator. (author)

  5. Simulating threshold voltage shift of MOS devices due to radiation in the low-dose range

    Wan Xin Heng; Gao Wen Yu; Huang Ru; Wang Yang Yuan

    2002-01-01

    An analytical MOSFET threshold voltage shift model due to radiation in the low-dose range has been developed for circuit simulations. Experimental data in the literature shows that the model predictions are in good agreement. It is simple in functional form and hence computationally efficient. It can be used as a basic circuit simulation tool for analysing MOSFET exposed to a nuclear environment up to about 1 Mrad(Si). In accordance with common believe, radiation induced absolute change of threshold voltage was found to be larger in irradiated PMOS devices. However, if the radiation sensitivity is defined in the way authors did it, the results indicated NMOS rather than PMOS devices are more sensitive, specially at low doses. This is important from the standpoint of their possible application in dosimetry

  6. Integral and Lagrangian simulations of particle and radiation transport in plasma

    Christlieb, A J; Hitchon, W N G; Lawler, J E; Lister, G G

    2009-01-01

    Accurate integral and Lagrangian models of transport in plasmas, in which the models reflect the actual physical behaviour as closely as possible, are presented. These methods are applied to the behaviour of particles and photons in plasmas. First, to show how these types of models arise in a wide range of plasma physics applications, an application to radiation transport in a lighting discharge is given. The radiation transport is solved self-consistently with a model of the discharge to provide what are believed to be very accurate 1D simulations of fluorescent lamps. To extend these integral methods to higher dimensions is computationally very costly. The wide utility of 'treecodes' in solving massive integral problems in plasma physics is discussed, and illustrated in modelling vortex formation in a Penning trap, where a remarkably detailed simulation of vortex formation in the trap is obtained. Extension of treecode methods to other integral problems such as radiation transport is under consideration.

  7. Net-zero Building Cluster Simulations and On-line Energy Forecasting for Adaptive and Real-Time Control and Decisions

    Li, Xiwang

    Buildings consume about 41.1% of primary energy and 74% of the electricity in the U.S. Moreover, it is estimated by the National Energy Technology Laboratory that more than 1/4 of the 713 GW of U.S. electricity demand in 2010 could be dispatchable if only buildings could respond to that dispatch through advanced building energy control and operation strategies and smart grid infrastructure. In this study, it is envisioned that neighboring buildings will have the tendency to form a cluster, an open cyber-physical system to exploit the economic opportunities provided by a smart grid, distributed power generation, and storage devices. Through optimized demand management, these building clusters will then reduce overall primary energy consumption and peak time electricity consumption, and be more resilient to power disruptions. Therefore, this project seeks to develop a Net-zero building cluster simulation testbed and high fidelity energy forecasting models for adaptive and real-time control and decision making strategy development that can be used in a Net-zero building cluster. The following research activities are summarized in this thesis: 1) Development of a building cluster emulator for building cluster control and operation strategy assessment. 2) Development of a novel building energy forecasting methodology using active system identification and data fusion techniques. In this methodology, a systematic approach for building energy system characteristic evaluation, system excitation and model adaptation is included. The developed methodology is compared with other literature-reported building energy forecasting methods; 3) Development of the high fidelity on-line building cluster energy forecasting models, which includes energy forecasting models for buildings, PV panels, batteries and ice tank thermal storage systems 4) Small scale real building validation study to verify the performance of the developed building energy forecasting methodology. The outcomes of

  8. Simulating the net ecosystem CO

    Vuichard, Nicolas; Ciais, Philippe; Viovy, Nicolas; Li, Longhui; Ceschia, Eric; Wattenbach, Martin; Bernhofer, Christian; Emmel, Carmen; Grünwald, Thomas; Jans, Wilma; Loubet, Benjamin; Wu, Xiuchen

    2016-01-01

    Over the last decade, efforts have been carried on to develop and evaluate versions of global terrestrial ecosystem models (GTEM) in which crop specificities are represented. The goal of this study is to evaluate the ability of the ORCHIDEE-STICS (Organising Carbon and Hydrology In Dynamic

  9. Monte Carlo simulation for radiation dose in children radiology

    Mendes, Hitalo R.; Tomal, Alessandra

    2016-01-01

    The dosimetry in pediatric radiology is essential due to the higher risk that children have in comparison to adults. The focus of this study is to present how the dose varies depending on the depth in a 10 year old and a newborn, for this purpose simulations are made using the Monte Carlo method. Potential differences were considered 70 and 90 kVp for the 10 year old and 70 and 80 kVp for the newborn. The results show that in both cases, the dose at the skin surface is larger for smaller potential value, however, it decreases faster for larger potential values. Another observation made is that because the newborn is less thick the ratio between the initial dose and the final is lower compared to the case of a 10 year old, showing that it is possible to make an image using a smaller entrance dose in the skin, keeping the same level of exposure at the detector. (author)

  10. Changes in the specific migration characteristics of packaging-food simulant combinations caused by ionizing radiation: Effect of food simulant

    Zygoura, Panagiota D., E-mail: me00806@cc.uoi.g [Laboratory of Food Chemistry and Technology, Department of Chemistry, University of Ioannina, GR-45110 Ioannina (Greece); Paleologos, Evangelos K.; Kontominas, Michael G. [Laboratory of Food Chemistry and Technology, Department of Chemistry, University of Ioannina, GR-45110 Ioannina (Greece)

    2011-08-15

    The primary objective of the present study was to evaluate the extent to which the affinity of the surrounding medium for the migrant, as well as the packaging material, affects the specific migration characteristics of the latter. For this purpose, migration tests were conducted with vinylidene chloride copolymer (PVDC/PVC) in contact with the EU specified solvents simulating all food types: namely, distilled water, 3% w/v acetic acid, 10% v/v ethanol and isooctane. Migration testing was carried out at 40 {sup o}C for 10 days for the aqueous simulants, and at 20 {sup o}C for 2 days for the fatty food simulant (). In addition, food-grade saran film was subjected to ionizing radiation treatment with a [{sup 60}Co] source at doses equal to 5, 15 and 25 kGy. Acetyl tributyl citrate (ATBC) plasticizer levels were monitored as a function of time for untreated, as well as gamma-irradiated packaging material, with a secondary objective to investigate the effect of ionizing radiation on polymer/migrant/surrounding medium interactions. Depending on the food simulant, determination of the analyte was performed by either direct gas chromatographic analysis, or surfactant (Triton X-114) mediated extraction followed by gas chromatographic-flame ionization detection (GC-FID). ATBC concentrations determined in aqueous and fatty food simulants were 0.216-0.497 and 5.0-5.9 mg/L, respectively. Therefore, the most efficient extracting medium of plasticizers in vinyl chloride copolymers is the non-polar isooctane. Moreover, an extremely high rate of ATBC migration into isooctane during the early stages of contact was observed. The above observation verifies the aggressiveness of isooctane towards plastic packaging materials. Amongst the aqueous food simulants tested, the 10% ethanol solution demonstrated the highest migration levels. Gamma-irradiation enhanced ATBC migration; specific migration levels increased with increasing contact time and radiation dose. This was expected, since

  11. Changes in the specific migration characteristics of packaging-food simulant combinations caused by ionizing radiation: Effect of food simulant

    Zygoura, Panagiota D.; Paleologos, Evangelos K.; Kontominas, Michael G.

    2011-08-01

    The primary objective of the present study was to evaluate the extent to which the affinity of the surrounding medium for the migrant, as well as the packaging material, affects the specific migration characteristics of the latter. For this purpose, migration tests were conducted with vinylidene chloride copolymer (PVDC/PVC) in contact with the EU specified solvents simulating all food types: namely, distilled water, 3% w/v acetic acid, 10% v/v ethanol and isooctane. Migration testing was carried out at 40 °C for 10 days for the aqueous simulants, and at 20 °C for 2 days for the fatty food simulant (EC, 1997; EEC, 1993). In addition, food-grade saran film was subjected to ionizing radiation treatment with a [60Co] source at doses equal to 5, 15 and 25 kGy. Acetyl tributyl citrate (ATBC) plasticizer levels were monitored as a function of time for untreated, as well as gamma-irradiated packaging material, with a secondary objective to investigate the effect of ionizing radiation on polymer/migrant/surrounding medium interactions. Depending on the food simulant, determination of the analyte was performed by either direct gas chromatographic analysis, or surfactant (Triton X-114) mediated extraction followed by gas chromatographic-flame ionization detection (GC-FID). ATBC concentrations determined in aqueous and fatty food simulants were 0.216-0.497 and 5.0-5.9 mg/L, respectively. Therefore, the most efficient extracting medium of plasticizers in vinyl chloride copolymers is the non-polar isooctane. Moreover, an extremely high rate of ATBC migration into isooctane during the early stages of contact was observed. The above observation verifies the aggressiveness of isooctane towards plastic packaging materials. Amongst the aqueous food simulants tested, the 10% ethanol solution demonstrated the highest migration levels. Gamma-irradiation enhanced ATBC migration; specific migration levels increased with increasing contact time and radiation dose. This was expected

  12. Changes in the specific migration characteristics of packaging-food simulant combinations caused by ionizing radiation: Effect of food simulant

    Zygoura, Panagiota D.; Paleologos, Evangelos K.; Kontominas, Michael G.

    2011-01-01

    The primary objective of the present study was to evaluate the extent to which the affinity of the surrounding medium for the migrant, as well as the packaging material, affects the specific migration characteristics of the latter. For this purpose, migration tests were conducted with vinylidene chloride copolymer (PVDC/PVC) in contact with the EU specified solvents simulating all food types: namely, distilled water, 3% w/v acetic acid, 10% v/v ethanol and isooctane. Migration testing was carried out at 40 o C for 10 days for the aqueous simulants, and at 20 o C for 2 days for the fatty food simulant (). In addition, food-grade saran film was subjected to ionizing radiation treatment with a [ 60 Co] source at doses equal to 5, 15 and 25 kGy. Acetyl tributyl citrate (ATBC) plasticizer levels were monitored as a function of time for untreated, as well as gamma-irradiated packaging material, with a secondary objective to investigate the effect of ionizing radiation on polymer/migrant/surrounding medium interactions. Depending on the food simulant, determination of the analyte was performed by either direct gas chromatographic analysis, or surfactant (Triton X-114) mediated extraction followed by gas chromatographic-flame ionization detection (GC-FID). ATBC concentrations determined in aqueous and fatty food simulants were 0.216-0.497 and 5.0-5.9 mg/L, respectively. Therefore, the most efficient extracting medium of plasticizers in vinyl chloride copolymers is the non-polar isooctane. Moreover, an extremely high rate of ATBC migration into isooctane during the early stages of contact was observed. The above observation verifies the aggressiveness of isooctane towards plastic packaging materials. Amongst the aqueous food simulants tested, the 10% ethanol solution demonstrated the highest migration levels. Gamma-irradiation enhanced ATBC migration; specific migration levels increased with increasing contact time and radiation dose. This was expected, since ATBC did not

  13. The use of discrete-event simulation modelling to improve radiation therapy planning processes.

    Werker, Greg; Sauré, Antoine; French, John; Shechter, Steven

    2009-07-01

    The planning portion of the radiation therapy treatment process at the British Columbia Cancer Agency is efficient but nevertheless contains room for improvement. The purpose of this study is to show how a discrete-event simulation (DES) model can be used to represent this complex process and to suggest improvements that may reduce the planning time and ultimately reduce overall waiting times. A simulation model of the radiation therapy (RT) planning process was constructed using the Arena simulation software, representing the complexities of the system. Several types of inputs feed into the model; these inputs come from historical data, a staff survey, and interviews with planners. The simulation model was validated against historical data and then used to test various scenarios to identify and quantify potential improvements to the RT planning process. Simulation modelling is an attractive tool for describing complex systems, and can be used to identify improvements to the processes involved. It is possible to use this technique in the area of radiation therapy planning with the intent of reducing process times and subsequent delays for patient treatment. In this particular system, reducing the variability and length of oncologist-related delays contributes most to improving the planning time.

  14. Role of Longwave Cloud-Radiation Feedback in the Simulation of the Madden-Julian Oscillation

    Kim, Daehyun; Ahn, Min-Seop; Kang, In-Sik; Del Genio, Anthony D.

    2015-01-01

    The role of the cloud-radiation interaction in the simulation of the Madden-Julian oscillation (MJO) is investigated. A special focus is on the enhancement of column-integrated diabatic heating due to the greenhouse effects of clouds and moisture in the region of anomalous convection. The degree of this enhancement, the greenhouse enhancement factor (GEF), is measured at different precipitation anomaly regimes as the negative ratio of anomalous outgoing longwave radiation to anomalous precipitation. Observations show that the GEF varies significantly with precipitation anomaly and with the MJO cycle. The greenhouse enhancement is greater in weak precipitation anomaly regimes and its effectiveness decreases monotonically with increasing precipitation anomaly. The GEF also amplifies locally when convection is strengthened in association with the MJO, especially in the weak precipitation anomaly regime (less than 5 mm day(exp -1)). A robust statistical relationship is found among CMIP5 climate model simulations between the GEF and the MJO simulation fidelity. Models that simulate a stronger MJO also simulate a greater GEF, especially in the weak precipitation anomaly regime (less than 5 mm day(exp -1)). Models with a greater GEF in the strong precipitation anomaly regime (greater than 30 mm day(-1)) represent a slightly slower MJO propagation speed. Many models that lack the MJO underestimate the GEF in general and in particular in the weak precipitation anomaly regime. The results herein highlight that the cloud-radiation interaction is a crucial process for climate models to correctly represent the MJO.

  15. Infrared spectroscopic analysis of the effects of simulated space radiation on a polyimide

    Ferl, J. E.; Long, E. R., Jr.

    1981-01-01

    Infrared spectroscopic techniques have been used to study the effects of electron radiation on the polyimide PMDA-p,p-prime- ODA. The radiation exposures were made at various dose rates, for a total dose approximately equal to that for 30 years of exposure to electron radiation in geosynchronous earth orbit. At high dose rates the major effect was probably the formation of a polyisoimide or a charged quaternary amine, and at the low dose rates the effect was a reduction in the amount or aromatic ether linkage. In addition, the effects of dose rate for a small total dose were studied. Elevated temperatures occurred at high dose rates and were, in part, probably the cause of the radiation product. The data suggest that dose rates for accelerated simulations of the space environment should not exceed 100,000 rads/sec.

  16. Development of radiation risk assessment simulator using system dynamics methodology

    Kang, Kyung Min; Jae, Moosung

    2008-01-01

    The potential magnitudes of radionuclide releases under severe accident loadings and offsite consequences as well as the overall risk (the product of accident frequencies and consequences) are analyzed and evaluated quantitatively in this study. The system dynamics methodology has been applied to predict the time-dependent behaviors such as feedback and dependency as well as to model uncertain behavior of complex physical system. It is used to construct the transfer mechanisms of time dependent radioactivity concentration and to evaluate them. Dynamic variations of radio activities are simulated by considering several effects such as deposition, weathering, washout, re-suspension, root uptake, translocation, leaching, senescence, intake, and excretion of soil. The time-dependent radio-ecological model applicable to Korean specific environment has been developed in order to assess the radiological consequences following the short-term deposition of radio-nuclides during severe accidents nuclear power plant. An ingestion food chain model can estimate time dependent radioactivity concentrations in foodstuffs. And it is also shown that the system dynamics approach is useful for analyzing the phenomenon of the complex system as well as the behavior of structure values with respect to time. The output of this model (Bq ingested per Bq m - 2 deposited) may be multiplied by the deposition and a dose conversion factor (Gy Bq -1 ) to yield organ-specific doses. The model may be run deterministically to yield a single estimate or stochastic distributions by 'Monte-Carlo' calculation that reflects uncertainty of parameter and model uncertainties. The results of this study may contribute to identifying the relative importance of various parameters occurred in consequence analysis, as well as to assessing risk reduction effects in accident management. (author)

  17. Photodegradation of antibiotics under simulated solar radiation: implications for their environmental fate.

    Batchu, Sudha Rani; Panditi, Venkata R; O'Shea, Kevin E; Gardinali, Piero R

    2014-02-01

    Roxithromycin, erythromycin, ciprofloxacin and sulfamethoxazole are frequently detected antibiotics in environmental waters. Direct and indirect photolysis of these problematic antibiotics were investigated in pure and natural waters (fresh and salt water) under irradiation of different light sources. Fundamental photolysis parameters such as molar absorption coefficient, quantum yield and first order rate constants are reported and discussed. The antibiotics are degraded fastest under ultraviolet 254 nm, followed by 350 nm and simulated solar radiation. The composition of the matrix (pH, dissolved organic content, chloride ion concentration) played a significant role in the observed photodegradation. Under simulated solar radiation, ciprofloxacin and sulfamethoxazole degrade relatively quickly with half-lives of 0.5 and 1.5h, respectively. However, roxithromycin and erythromycin, macrolides are persistent (half-life: 2.4-10 days) under solar simulation. The transformation products (15) of the targeted antibiotics produced under irradiation experiments were identified using high resolution mass spectrometry and degradation pathways were proposed. © 2013.

  18. ARTS, the Atmospheric Radiative Transfer Simulator - version 2.2, the planetary toolbox edition

    Buehler, Stefan A.; Mendrok, Jana; Eriksson, Patrick; Perrin, Agnès; Larsson, Richard; Lemke, Oliver

    2018-04-01

    This article describes the latest stable release (version 2.2) of the Atmospheric Radiative Transfer Simulator (ARTS), a public domain software for radiative transfer simulations in the thermal spectral range (microwave to infrared). The main feature of this release is a planetary toolbox that allows simulations for the planets Venus, Mars, and Jupiter, in addition to Earth. This required considerable model adaptations, most notably in the area of gaseous absorption calculations. Other new features are also described, notably radio link budgets (including the effect of Faraday rotation that changes the polarization state) and the treatment of Zeeman splitting for oxygen spectral lines. The latter is relevant, for example, for the various operational microwave satellite temperature sensors of the Advanced Microwave Sounding Unit (AMSU) family.

  19. High dose radiation damage in nuclear energy structural materials investigated by heavy ion irradiation simulation

    Zheng Yongnan; Xu Yongjun; Yuan Daqing

    2014-01-01

    Structural materials in ITER, ADS and fast reactor suffer high dose irradiations of neutrons and/or protons, that leads to severe displacement damage up to lOO dpa per year. Investigation of radiation damage induced by such a high dose irradiation has attracted great attention along with the development of nuclear energy facilities of new generation. However, it is deeply hampered for the lacking of high dose neutron and proton sources. Irradiation simulation of heavy ions produced by accelerators opens up an effective way for laboratory investigation of high dose irradiation induced radiation damage encountered in the ITER, ADS, etc. Radiation damage is caused mainly by atomic displacement in materials. The displacement rate of heavy ions is about lO 3 ∼10 7 orders higher than those of neutrons and protons. High displacement rate of heavy ions significantly reduces the irradiation time. The heavy ion irradiation simulation technique (HIIS) technique has been developed at China Institute of Atomic Energy and a series of the HIIS experiments have been performed to investigate radiation damage in stainless steels, tungsten and tantalum at irradiation temperatures from room temperature to 800 ℃ and in the irradiation dose region up to 100 dpa. The experimental results show that he radiation swelling peak for the modified stainless steel appears in the temperature region around 580 ℃ and the radiation damage is more sensitive to the temperature, the size of the radiation induced vacancy cluster or void increase with the increasing of the irradiation dose, and among the three materials the home-made modified stainless steel has the best radiation resistant property. (authors)

  20. RITRACKS: A Software for Simulation of Stochastic Radiation Track Structure, Micro and Nanodosimetry, Radiation Chemistry and DNA Damage for Heavy Ions

    Plante, I; Wu, H

    2014-01-01

    The code RITRACKS (Relativistic Ion Tracks) has been developed over the last few years at the NASA Johnson Space Center to simulate the effects of ionizing radiations at the microscopic scale, to understand the effects of space radiation at the biological level. The fundamental part of this code is the stochastic simulation of radiation track structure of heavy ions, an important component of space radiations. The code can calculate many relevant quantities such as the radial dose, voxel dose, and may also be used to calculate the dose in spherical and cylindrical targets of various sizes. Recently, we have incorporated DNA structure and damage simulations at the molecular scale in RITRACKS. The direct effect of radiations is simulated by introducing a slight modification of the existing particle transport algorithms, using the Binary-Encounter-Bethe model of ionization cross sections for each molecular orbitals of DNA. The simulation of radiation chemistry is done by a step-by-step diffusion-reaction program based on the Green's functions of the diffusion equation]. This approach is also used to simulate the indirect effect of ionizing radiation on DNA. The software can be installed independently on PC and tablets using the Windows operating system and does not require any coding from the user. It includes a Graphic User Interface (GUI) and a 3D OpenGL visualization interface. The calculations are executed simultaneously (in parallel) on multiple CPUs. The main features of the software will be presented.

  1. Shielding calculations for NET

    Verschuur, K.A.; Hogenbirk, A.

    1991-05-01

    In the European Fusion Technology Programme there is only a small activity on research and development for fusion neutronics. Never-the-less, looking further than blanket design now, as ECN is getting involved in design of radiation shields for the coils and biological shields, it becomes apparent that fusion neutronics as a whole still needs substantial development. Existing exact codes for calculation of complex geometries like MCNP and DORT/TORT are put over the limits of their numerical capabilities, whilst approximate codes for complex geometries like FURNACE and MERCURE4 are put over the limits of their modelling capabilities. The main objective of this study is just to find out how far we can get with existing codes in obtaining reliable values for the radiation levels inside and outside the cryostat/shield during operation and after shut-down. Starting with a 1D torus model for preliminary parametric studies, more dimensional approximation of the torus or parts of it including the main heterogeneities should follow. Regular contacts with the NET-Team are kept, to be aware of main changes in NET design that might affect our calculation models. Work on the contract started 1 July 1990. The technical description of the contract is given. (author). 14 refs.; 4 figs.; 1 tab

  2. SIMULATING THE FORMATION OF MASSIVE PROTOSTARS. I. RADIATIVE FEEDBACK AND ACCRETION DISKS

    Klassen, Mikhail; Pudritz, Ralph E. [Department of Physics and Astronomy, McMaster University, 1280 Main Street W, Hamilton, ON L8S 4M1 (Canada); Kuiper, Rolf [Institute of Astronomy and Astrophysics, University of Tübingen, Auf der Morgenstelle 10, D-72076 Tübingen (Germany); Peters, Thomas [Max-Planck-Institut für Astrophysik, Karl-Schwarzschild-Strasse 1, D-85748 Garching (Germany); Banerjee, Robi, E-mail: klassm@mcmaster.ca [Hamburger Sternwarte, Universität Hamburg, Gojenbergsweg 112, D-21029 Hamburg (Germany)

    2016-05-20

    We present radiation hydrodynamic simulations of collapsing protostellar cores with initial masses of 30, 100, and 200 M {sub ⊙}. We follow their gravitational collapse and the formation of a massive protostar and protostellar accretion disk. We employ a new hybrid radiative feedback method blending raytracing techniques with flux-limited diffusion for a more accurate treatment of the temperature and radiative force. In each case, the disk that forms becomes Toomre-unstable and develops spiral arms. This occurs between 0.35 and 0.55 freefall times and is accompanied by an increase in the accretion rate by a factor of 2–10. Although the disk becomes unstable, no other stars are formed. In the case of our 100 and 200 M {sub ⊙} simulations, the star becomes highly super-Eddington and begins to drive bipolar outflow cavities that expand outwards. These radiatively driven bubbles appear stable, and appear to be channeling gas back onto the protostellar accretion disk. Accretion proceeds strongly through the disk. After 81.4 kyr of evolution, our 30 M {sub ⊙} simulation shows a star with a mass of 5.48 M {sub ⊙} and a disk of mass 3.3 M {sub ⊙}, while our 100 M {sub ⊙} simulation forms a 28.8 M {sub ⊙} mass star with a 15.8 M {sub ⊙} disk over the course of 41.6 kyr, and our 200 M {sub ⊙} simulation forms a 43.7 M {sub ⊙} star with an 18 M {sub ⊙} disk in 21.9 kyr. In the absence of magnetic fields or other forms of feedback, the masses of the stars in our simulation do not appear to be limited by their own luminosities.

  3. Study of radiation damage in solid materials by simulating physical processes

    Pinnera Hernandez, Ibrahin

    2006-12-01

    Nowadays the damage induced by different types of radiation in advanced materials is widely studied. Especially those materials involved in experiments and developing of new technologies, such as high critical temperature superconductors, semiconductors, metals. These materials are the basis constituents of radiation detectors, particle accelerators, etc. One way of studying this kind of damage is through the determination of the displacements per atom (dpa) induced by the radiation in these materials. This magnitude is one of the measures of the provoked radiation damage. On this direction, the present thesis deals with the study of two types of materials through mathematical simulation of physical processes taking place in the radiation transport. Ceramic superconductor Yba 2 Cu 3 O 7-x and metal Fe are the selected materials. The energy range of the incident gamma radiation goes from a few keV to 15 MeV. The MCNPX version 2.6b is used to determine the physical magnitudes required to calculate the distribution of displacements per atom within these materials, using an algorithm implemented for this purpose. Finally, a comparison between the obtained dpa profiles and the corresponding of energy deposition by radiation in these same materials and the possible linear dependence between both quantities is discussed. (Author)

  4. A Chinese Visible Human-based computational female pelvic phantom for radiation dosimetry simulation

    Nan, H.; Jinlu, S.; Shaoxiang, Z.; Qing, H.; Li-wen, T.; Chengjun, G.; Tang, X.; Jiang, S. B.; Xiano-lin, Z.

    2010-01-01

    Accurate voxel phantom is needed for dosimetric simulation in radiation therapy for malignant tumors in female pelvic region. However, most of the existing voxel phantoms are constructed on the basis of Caucasian or non-Chinese population. Materials and Methods: A computational framework for constructing female pelvic voxel phantom for radiation dosimetry was performed based on Chinese Visible Human datasets. First, several organs within pelvic region were segmented from Chinese Visible Human datasets. Then, polygonization and voxelization were performed based on the segmented organs and a 3D computational phantom is built in the form of a set of voxel arrays. Results: The generated phantom can be converted and loaded into treatment planning system for radiation dosimetry calculation. From the observed dosimetric results of those organs and structures, we can evaluate their absorbed dose and implement some simulation studies. Conclusion: A voxel female pelvic phantom was developed from Chinese Visible Human datasets. It can be utilized for dosimetry evaluation and planning simulation, which would be very helpful to improve the clinical performance and reduce the radiation toxicity on organ at risk.

  5. New development of integrated CT simulation system for radiation therapy planning

    Kushima, Takeyuki; Kono, Michio

    1993-01-01

    In order to put more accurate radiotherapy into practice, a radiotherapy planning system using CT, which is named CT simulation system, has been developed and introduced at Kobe University Hospital. The CT simulation system consists of a CT scanner, an image processing work-station, and a laser marking system. The target area of radiation is determined on each CT axial image of scout view in the work-station. Three-dimensional treatment planning is feasible on the basis of the two-dimensional tumor information in CT axial images. After setting treatment parameters, the contour of the radiation field on beam's eye view and the iso-center position are calculated by computer. This system makes it possible to choose an appropriate irradiation method and an optimal dose distribution. In the present study we examined the fundamental capability of this system. The laser marking system proved to have a very high degree of accuracy. The outcome of a phantom test raised the strong possibility that this system may be applied clinically. In addition to these basic findings, this paper describes preliminary clinical observations that support the good reproducibility of the radiation field projected with the CT simulator. In conclusion, this system is of high value for radiation therapy planning. (author)

  6. 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).

  7. Evaluation of light Collection in Radiation Portal Monitor with Multi PMTs using Monte Carlo simulation

    Lim, Chang Hwy; Park, Jong Won; Lee, Junghee; Moon, Myung Kook; Kim, Jongyul; Lee, Suhyun

    2015-01-01

    A plastic scintillator in the RPM is suited for the γ-ray detection of various-range energy and is the cost effective radiation detection material. In order to well inspect emitted radiation from the container cargo, the radiation detection area of a plastic scintillator should be larger than other general purpose radiation detector. However, the large size plastic scintillator affects the light collection efficiency at the photo-sensitive sensor due to the long light transport distance and light collisions in a plastic scintillator. Therefore, the improvement of light collection efficiency in a RPM is one of the major issues for the high performance RPM development. We calculated the change of the number of collected light according to changing of the attachment position and number of PMT. To calculate the number of collected light, the DETECT2000 and MCNP6 Monte Carlo simulation software tool was used. Response signal performance of RPM system is affected by the position of the incident radiation. If the distance between the radiation source and a PMT is long, the number of loss signal is larger. Generally, PMTs for signal detection in RPM system has been attached on one side of plastic scintillator. In contrast, RPM model in the study have 2 PMTs, which attached at the two side of plastic scintillator. We estimated difference between results using the old method and our method. According to results, uniformity of response signal was better than method using one side. If additive simulation and experiment is performed, it will be possible to develop the improved RPM system. In the future, we will perform additive simulation about many difference RPM model

  8. Relativistic, Viscous, Radiation Hydrodynamic Simulations of Geometrically Thin Disks. I. Thermal and Other Instabilities

    Fragile, P. Chris; Etheridge, Sarina M.; Anninos, Peter; Mishra, Bhupendra; Kluźniak, Włodek

    2018-04-01

    We present results from two-dimensional, general relativistic, viscous, radiation hydrodynamic numerical simulations of Shakura–Sunyaev thin disks accreting onto stellar-mass Schwarzschild black holes. We consider cases on both the gas- and radiation-pressure-dominated branches of the thermal equilibrium curve, with mass accretion rates spanning the range from \\dot{M}=0.01{L}Edd}/{c}2 to 10L Edd/c 2. The simulations directly test the stability of this standard disk model on the different branches. We find clear evidence of thermal instability for all radiation-pressure-dominated disks, resulting universally in the vertical collapse of the disks, which in some cases then settle onto the stable, gas-pressure-dominated branch. Although these results are consistent with decades-old theoretical predictions, they appear to be in conflict with available observational data from black hole X-ray binaries. We also find evidence for a radiation-pressure-driven instability that breaks the unstable disks up into alternating rings of high and low surface density on a timescale comparable to the thermal collapse. Since radiation is included self-consistently in the simulations, we are able to calculate light curves and power density spectra (PDS). For the most part, we measure radiative efficiencies (ratio of luminosity to mass accretion rate) close to 6%, as expected for a nonrotating black hole. The PDS appear as broken power laws, with a break typically around 100 Hz. There is no evidence of significant excess power at any frequencies, i.e., no quasi-periodic oscillations are observed.

  9. Considerations for the independent reaction times and step-by-step methods for radiation chemistry simulations

    Plante, Ianik; Devroye, Luc

    2017-10-01

    Ionizing radiation interacts with the water molecules of the tissues mostly by ionizations and excitations, which result in the formation of the radiation track structure and the creation of radiolytic species such as H.,.OH, H2, H2O2, and e-aq. After their creation, these species diffuse and may chemically react with the neighboring species and with the molecules of the medium. Therefore radiation chemistry is of great importance in radiation biology. As the chemical species are not distributed homogeneously, the use of conventional models of homogeneous reactions cannot completely describe the reaction kinetics of the particles. Actually, many simulations of radiation chemistry are done using the Independent Reaction Time (IRT) method, which is a very fast technique to calculate radiochemical yields but which do not calculate the positions of the radiolytic species as a function of time. Step-by-step (SBS) methods, which are able to provide such information, have been used only sparsely because these are time-consuming in terms of calculation. Recent improvements in computer performance now allow the regular use of the SBS method in radiation chemistry. The SBS and IRT methods are both based on the Green's functions of the diffusion equation (GFDE). In this paper, several sampling algorithms of the GFDE and for the IRT method are presented. We show that the IRT and SBS methods are exactly equivalent for 2-particles systems for diffusion and partially diffusion-controlled reactions between non-interacting particles. We also show that the results obtained with the SBS simulation method with periodic boundary conditions are in agreement with the predictions by classical reaction kinetics theory, which is an important step towards using this method for modelling of biochemical networks and metabolic pathways involved in oxidative stress. Finally, the first simulation results obtained with the code RITRACKS (Relativistic Ion Tracks) are presented.

  10. Evaluation of light Collection in Radiation Portal Monitor with Multi PMTs using Monte Carlo simulation

    Lim, Chang Hwy; Park, Jong Won; Lee, Junghee [Korea Research Institute of Ships and Ocean Engineering, Daejeon (Korea, Republic of); Moon, Myung Kook; Kim, Jongyul; Lee, Suhyun [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2015-10-15

    A plastic scintillator in the RPM is suited for the γ-ray detection of various-range energy and is the cost effective radiation detection material. In order to well inspect emitted radiation from the container cargo, the radiation detection area of a plastic scintillator should be larger than other general purpose radiation detector. However, the large size plastic scintillator affects the light collection efficiency at the photo-sensitive sensor due to the long light transport distance and light collisions in a plastic scintillator. Therefore, the improvement of light collection efficiency in a RPM is one of the major issues for the high performance RPM development. We calculated the change of the number of collected light according to changing of the attachment position and number of PMT. To calculate the number of collected light, the DETECT2000 and MCNP6 Monte Carlo simulation software tool was used. Response signal performance of RPM system is affected by the position of the incident radiation. If the distance between the radiation source and a PMT is long, the number of loss signal is larger. Generally, PMTs for signal detection in RPM system has been attached on one side of plastic scintillator. In contrast, RPM model in the study have 2 PMTs, which attached at the two side of plastic scintillator. We estimated difference between results using the old method and our method. According to results, uniformity of response signal was better than method using one side. If additive simulation and experiment is performed, it will be possible to develop the improved RPM system. In the future, we will perform additive simulation about many difference RPM model.

  11. Simulating the impacts of land use in northwest Europe on Net Ecosystem Exchange (NEE): the role of arable ecosystems, grasslands and forest plantations in climate change mitigation.

    Abdalla, Mohamed; Saunders, Matthew; Hastings, Astley; Williams, Mike; Smith, Pete; Osborne, Bruce; Lanigan, Gary; Jones, Mike B

    2013-11-01

    In this study, we compared measured and simulated Net Ecosystem Exchange (NEE) values from three wide spread ecosystems in the southeast of Ireland (forest, arable and grassland), and investigated the suitability of the DNDC (the DeNitrification-DeComposition) model to estimate present and future NEE. Although, the field-DNDC version overestimated NEE at temperatures >5 °C, forest-DNDC under-estimated NEE at temperatures >5 °C. The results suggest that the field/forest DNDC models can successfully estimate changes in seasonal and annual NEE from these ecosystems. Differences in NEE were found to be primarily land cover specific. The annual NEE was similar for the grassland and arable sites, but due to the contribution of exported carbon, the soil carbon increased at the grassland site and decreased at the arable site. The NEE of the forest site was an order of magnitude larger than that of the grassland or arable ecosystems, with large amounts of carbon stored in woody biomass and the soil. The average annual NEE, GPP and Reco values over the measurement period were -904, 2379 and 1475 g C m(-2) (forest plantations), -189, 906 and 715 g C m(-2) (arable systems) and -212, 1653 and 1444 g C m(-2) (grasslands), respectively. The average RMSE values were 3.8 g C m(-2) (forest plantations), 0.12 g C m(-2) (arable systems) and 0.21 g C m(-2) (grasslands). When these models were run with climate change scenarios to 2060, predictions show that all three ecosystems will continue to operate as carbon sinks. Further, climate change may decrease the carbon sink strength in the forest plantations by up to 50%. This study supports the use of the DNDC model as a valid tool to predict the consequences of climate change on NEE from different ecosystems. Copyright © 2012 Elsevier B.V. All rights reserved.

  12. PUMN: a radiation damage simulation computer program for the WINERY system

    Kuspa, J.P.

    1976-01-01

    The WINERY Radiation Damage Computer Simulation System will attempt to solve the entire radiation damage problem from the incident radiation to the property changes which occur in the material, using a set of interrelated computer programs. Computer simulation may be indispensable to the study of the radiation damage to materials in breeder and fusion reactors. WINERY is introduced with this work, and one portion of the system, the PUMN program, is developed and used to obtain important radiation damage results with Fe 3 Al crystal. PUMN is a program which simulates the response of the atoms in a crystal to a knock-on atom. It yields the damage configuration of the crystal by considering the dynamic interaction of all the atoms of the computational cell, up to 1000 atoms. The trajectories of the atoms are calculated using the Nordsieck Method, which has a prediction step based upon Taylor series expansions of the position and its first five time derivatives, and has a correction sequence which uses coefficients which have been optimized for efficiency and accuracy. Other features, such as restart files, automatic time step control, and crystal extension, make PUMN a versatile program which can simulate cases of relatively high knock-on energy, at least up to 500 eV. The PUMN program provides the WINERY system with results for the number of displacements, N/sub d/, due to knock-on atoms with various energies. This study dealt exclusively with Fe 3 Al. The values of N/sub d/ for Fe 3 Al were obtained at two different energies, 100 eV and 500 eV, for a variety of initial directions

  13. A Global Three-Dimensional Radiation Hydrodynamic Simulation of a Self-Gravitating Accretion Disk

    Phillipson, Rebecca; Vogeley, Michael S.; McMillan, Stephen; Boyd, Patricia

    2018-01-01

    We present three-dimensional, radiation hydrodynamic simulations of initially thin accretion disks with self-gravity using the grid-based code PLUTO. We produce simulated light curves and spectral energy distributions and compare to observational data of X-ray binary (XRB) and active galactic nuclei (AGN) variability. These simulations are of interest for modeling the role of radiation in accretion physics across decades of mass and frequency. In particular, the characteristics of the time variability in various bandwidths can probe the timescales over which different physical processes dominate the accretion flow. For example, in the case of some XRBs, superorbital periods much longer than the companion orbital period have been observed. Smoothed particle hydrodynamics (SPH) calculations have shown that irradiation-driven warping could be the mechanism underlying these long periods. In the case of AGN, irradiation-driven warping is also predicted to occur in addition to strong outflows originating from thermal and radiation pressure driving forces, which are important processes in understanding feedback and star formation in active galaxies. We compare our simulations to various toy models via traditional time series analysis of our synthetic and observed light curves.

  14. Analysis of noise radiation mechanisms in hot subsonic jet from a validated large eddy simulation solution

    Lorteau, Mathieu, E-mail: mathieu.lorteau@onera.fr; Cléro, Franck, E-mail: franck.clero@onera.fr; Vuillot, François, E-mail: francois.vuillot@onera.fr [Onera–The French Aerospace Lab, F-92322 Châtillon (France)

    2015-07-15

    In the framework of jet noise computation, a numerical simulation of a subsonic turbulent hot jet is performed using large-eddy simulation. A geometrical tripping is used in order to trigger the turbulence at the nozzle exit. In a first part, the validity of the simulation is assessed by comparison with experimental measurements. The mean and rms velocity fields show good agreement, so do the azimuthal composition of the near pressure field and the far field spectra. Discrepancies remain close to the nozzle exit which lead to a limited overestimation of the pressure levels in both near and far fields, especially near the 90{sup ∘} angular sector. Two point correlation analyses are then applied to the data obtained from the simulation. These enable to link the downstream acoustic radiation, which is the main direction of radiation, to pressure waves developing in the shear layer and propagating toward the potential core end. The intermittency of the downstream acoustic radiation is evidenced and related to the coherent structures developing in the shear layer.

  15. Radiation dose assessment in nuclear plants through virtual simulations using a game engine

    Jorge, Carlos A.F.; Mol, Antonio C. A.; Aghina, Mauricio Alves C.

    2008-01-01

    Full text: This paper reports an R and D which has the purpose of performing dose assessment of workers in nuclear plants, through virtual simulations using a game engine. The main objective of this R and D is to support the planning of operational and maintenance routines in nuclear plants, aiming to reduce the dose received by workers. Game engine is the core of a computer game, that is usually made independent of both the scenarios and the original applications, and thus can be adapted for any other purposes, including scientific or technological ones. Computer games have experienced a great development in the last years, regarding computer graphics, 3D image rendering and the representation of the physics needed for the virtual simulations, such as gravity effect and collision among virtual components within the games. Thus, researchers do not need to develop an entire platform for virtual simulations, what would be a hard work itself, but they can rather take advantage of such well developed platforms, adapting them for their own applications. The game engine used in this R and D is part of a computer game widely used, Unreal, that has its source code partially open, and can be pursued for low cost. A nuclear plant in our Institution, Argonauta research reactor, has been virtually modeled in 3D, and trainees can navigate virtually through it, with realistic walking velocity, and experiencing collision. The modified game engine computes and displays in real-time the dose received by a virtual person, the avatar, as it walks through the plant, from the radiation dose rate distribution assigned to the virtual environment. In the beginning of this R and D, radiation dose rate measurements were previously collected by the radiological protection service, and input off-line to the game engine. Currently, on-line measurements can be also input to it, by taking advantage of the game's networking capabilities. A real radiation monitor has been used to collect real

  16. Computer simulation of radiation damage in HTGR elements and structural materials

    Gann, V.V.; Gurin, V.A.; Konotop, Yu.F.; Shilyaev, B.A.; Yamnitskij, V.A.

    1980-01-01

    The problem of mathematical simulation of radiation damages in material and items of HTGR is considered. A system-program complex IMITATOR, intended for imitation of neutron damages by means of charged particle beams, is used. Account of material composite structure and certain geometry of items permits to calculate fields of primary radiation damages and introductions of reaction products in composite fuel elements, microfuel elements, their shells, composite absorbing elements on the base of boron carbide, structural steels and alloys. A good correspondence of calculation and experimental burn-out of absorbing elements is obtained, application of absorbing element as medium for imitation experiments is grounded [ru

  17. Comprehensive Modelling and Simulation System for Decision Support in the Field of Radiation Potection

    Pecha, Petr; Hofman, Radek

    -, č. 81 (2010), s. 17-18 ISSN 0926-4981 R&D Projects: GA MŠk(CZ) 1M0572; GA ČR(CZ) GA102/07/1596 Institutional research plan: CEZ:AV0Z10750506 Keywords : decision support * modelling * radiation protection * environmental impact assessment * probability safety assessment Subject RIV: JF - Nuclear Energetics http://library.utia.cas.cz/separaty/2010/AS/pecha-comprehensive modelling and simulation system for decision support in the field of radiation potection.pdf

  18. MONTEC, an interactive fortran program to simulate radiation dose and dose-rate responses of populations

    Perry, K.A.; Szekely, J.G.

    1983-09-01

    The computer program MONTEC was written to simulate the distribution of responses in a population whose members are exposed to multiple radiation doses at variable dose rates. These doses and dose rates are randomly selected from lognormal distributions. The individual radiation responses are calculated from three equations, which include dose and dose-rate terms. Other response-dose/rate relationships or distributions can be incorporated by the user as the need arises. The purpose of this documentation is to provide a complete operating manual for the program. This version is written in FORTRAN-10 for the DEC system PDP-10

  19. Simulation and modeling for the stand-off radiation detection system (SORDS) using GEANT4

    Hoover, Andrew S [Los Alamos National Laboratory; Wallace, Mark [Los Alamos National Laboratory; Galassi, Mark [Los Alamos National Laboratory; Mocko, Michal [Los Alamos National Laboratory; Palmer, David [Los Alamos National Laboratory; Schultz, Larry [Los Alamos National Laboratory; Tornga, Shawn [Los Alamos National Laboratory

    2009-01-01

    A Stand-Off Radiation Detection System (SORDS) is being developed through a joint effort by Raytheon, Los Alamos National Laboratory, Bubble Technology Industries, Radiation Monitoring Devices, and the Massachusetts Institute of Technology, for the Domestic Nuclear Detection Office (DNDO). The system is a mobile truck-based platform performing detection, imaging, and spectroscopic identification of gamma-ray sources. A Tri-Modal Imaging (TMI) approach combines active-mask coded aperture imaging, Compton imaging, and shadow imaging techniques. Monte Carlo simulation and modeling using the GEANT4 toolkit was used to generate realistic data for the development of imaging algorithms and associated software code.

  20. Effect of gamma radiation on chlorophylls content, net photosynthesis and respiration of Chlorella pyrenoidosa; Efecto de la radiacion gamma sobre la fotosintesis neta y la respiracion de Chlorella pyrenoidosa

    Martin, C; Fernandez, J

    1983-07-01

    The effect of five doses of gamma radiation: 10, 100, 500, 1000 and 5000 Gy on chlorophylls content, net photosynthesis and respiration of Chlorella pyrenoidosa has been studied. A decrease in chlorophylls levels is produced after irradiation at 500, 1000 and 5000 Gy, being, at first b chlorophyll affected to a greater extent than a chlorophyll. Net photosynthesis and respiration decline throughout the time of the observation after irradiation, this depressing effect being much more remarkable for the first one. Met photosynthesis inhibition levels of about 30% are got only five hours post irradiation at a dose of 5000 Gy. Radio estimation by low doses, although obtained in some cases for tho 10 Gy dose, has not been statistically confirmed. (Author) 23 refs.

  1. CFD-simulation of radiator for air cooling of microprocessors in a limitided space

    Trofimov V. E.

    2016-12-01

    Full Text Available One of the final stages of microprocessors development is heat test. This procedure is performed on a special stand, the main element of which is the switching PCB with one or more mounted microprocessor sockets, chipsets, interfaces, jumpers and other components which provide various modes of microprocessor operation. The temperature of microprocessor housing is typically changed using thermoelectric module. The cold surface of the module with controlled temperature is in direct thermal contact with the microprocessor housing designed for cooler installation. On the hot surface of the module a radiator is mounted. The radiator dissipates the cumulative heat flow from both the microprocessor and the module. High density PCB layout, the requirement of free access to the jumpers and interfaces, and the presence of numerous sensors limit the space for radiator mounting and require the use of an extremely compact radiator, especially in air cooling conditions. One of the possible solutions for this problem may reduce the area of the radiator heat-transfer surfaces due to a sharp growth of the heat transfer coefficient without increasing the air flow rate. To ensure a sharp growth of heat transfer coefficient on the heat-transfer surface one should make in the surface one or more dead-end cavities into which the impact air jets would flow. CFD simulation of this type of radiator has been conducted. The heat-aerodynamic characteristics and design recommendations for removing heat from microprocessors in a limited space have been determined.

  2. CHEMIFOGV - A Model to Simulate Radiation Fogs and their Interaction with Vegetation and Chemistry

    Winterrath, Tanja; Bott, Andreas

    2001-01-01

    Radiation fog is an important modifier of atmospheric compounds in the planetary boundary layer. In vegetated areas effects are especially pronounced due to the enlarged surface area. Besides affecting the lower boundary of atmospheric models fog acts as a multi-phase reaction chamber leading to acid deposition. Here we present the 1-dimensional radiation fog modelCHEMIFOG V to simulate regional radiation fog events. The key feature of the fog model is the detailed microphysics, where the aerosol/droplet spectrum is described with a joint 2-dimensional distribution, but also the dynamics, thermodynamics, and radiative transfer are calculated. To investigate the interaction between fog and the biosphere a multi-layer vegetation module, including a soil module as well as a dry deposition module were coupled. Vegetation influences the dynamics, thermodynamics, and the radiation field of the lowest atmospheric layers. With CHEMIFOG V , numerical case studies on dry and moist deposition processes on vegetation surfaces were performed. Hereby multi-phase chemistry and the processing of aerosols were considered. The results show that the chemical composition of the deposited fog droplets is mainly determined by the aerosol composition. Dry deposition fluxes are dependent on the incoming radiation and the leaves' surface conditions with respect to water coverage.Due to chemical aerosol processing and deposition, the aerosol spectrum is significantly modified in the planetary boundary layer

  3. Cost effectiveness of a radiation therapy simulator: a model for the determination of need

    Dritschilo, A.; Sherman, D.; Emami, B.; Piro, A.J.; Hellman, S.

    1979-01-01

    The requirement for a certificate-of-need for capital expenditures of $100,000 or more has placed a major constraint on purchases of new medical equipment. Consideration of a first principles argument has not proven compelling to the planning agencies in justifying the purchase of a radiation therapy simulator. Thus a strategy based on cost-effectiveness and the consequences of survival in successfully treated patients is proposed for equipment justification. We have reviewed the records of 18-month survivors among patients with lung cancer that were treated by irradiation; we observed 3 spinal cord injuries in non-simulated patients, whereas none were observed in patients who had the benefit of simulation. Considering the societal costs of spinal cord injury, a cost-benefit analysis of a simulator justifies the expense of this equipment

  4. Computer simulation of radiation-induced nanostructure formation in amorphous materials

    Li, K.-D.; Perez-Bergquist, Alejandro; Wang, Lumin

    2009-01-01

    In this study, 3D simulations based on a theoretical model were developed to investigate radiation-induced nanostructure formation in amorphous materials. Model variables include vacancy production and recombination rates, ion sputtering effects, and redeposition of sputtered atoms. In addition, a phase field model was developed to predict vacancy diffusion as a function of free energies of mixing and interfacial energies. The distribution profile of the vacancy production rate along the depth of an irradiated matrix was considered as a near Gaussian approximation according to Monte-Carlo TRIM code calculations. Dynamic processes responsible for nanostructure evolution were simulated by updating the vacancy concentration profile over time. Simulated morphologies include cellular nanoholes, nanowalls, nanovoids, and nanofibers, with the resultant morphology dependant upon the incident ion species and ion fluence. These simulated morphologies are consistent with experimental observations achieved under comparable experimental conditions. Our model provides a distinct numerical approach to accurately predicting morphological results for ion-irradiation-induced nanostructures.

  5. Comparison of a suspended radiation protection system versus standard lead apron for radiation exposure of a simulated interventionalist.

    Marichal, Daniel A; Anwar, Temoor; Kirsch, David; Clements, Jessica; Carlson, Luke; Savage, Clare; Rees, Chet R

    2011-04-01

    To evaluate the radiation protective characteristics of a system designed to enhance operator protection while eliminating weight to the body and allowing freedom of motion. Radiation doses to a mock interventionalist were measured with calibrated dosimeters in a clinical interventional suite. A standard lead apron (SLA; Pb equivalent, 0.5 mm) was compared with a suspended radiation protection system (ZeroGravity; Zgrav) that shields from the top of the head to the calves (except the right arm and left forearm) with a complex overhead motion system that eliminates weight on the operator and allows freedom of motion. Zgrav included a suspended lead apron with increased lead equivalency, greater length, proximal left arm and shoulder coverage, and a wraparound face shield of 0.5 mm Pb equivalency. A 26-cm-thick Lucite stack (ie, mock patient) created scatter during 10 controlled angiography sequences of 120 exposures each. Parameters included a field of view of 40 cm, table height of 94 cm, 124 cm from the tube to image intensifier, 50 cm from the image center to operator, 66 kVp, and 466-470 mA. Under identical conditions, average doses (SLA vs Zgrav) were 264 versus 3.4 (ratio, 78) to left axilla (P < .001), 456 versus 10.2 (ratio, 45) to left eye (P < .001), 379.4 versus 6.6 (ratio, 57) to right eye (P < .005), and 18.8 versus 1.2 (ratio, 16) to gonad (P < .001). Relative to a conventional lead apron, the Zgrav system provided a 16-78-fold decrease in radiation exposure for a mock interventionalist in a simulated clinical setting. Copyright © 2011 SIR. Published by Elsevier Inc. All rights reserved.

  6. Numerical simulation of thermal radiation from smoking flames; Numerische Simulation der Waermestrahlung von russenden Flammen

    Koch, T. [Duisburg Univ. (Gesamthochschule) (Germany). Lehrstuhl fuer Technische Chemie; Staus, S. [Duisburg Univ. (Gesamthochschule) (Germany). Lehrstuhl fuer Technische Chemie; Schoenbucher, A. [Duisburg Univ. (Gesamthochschule) (Germany). Lehrstuhl fuer Technische Chemie

    1997-08-01

    After presenting the most common semi-empirical simulation model, the authors describe the newly developed field model and its modules with their mathematical and physical fundamentals. First results are presented for the calculation of a diffusion flame. (orig./GL) [Deutsch] In der vorliegenden Arbeit wird, nach einer Darstellung der gebraeuchlichen halbempirischen Simulationsmodelle, das entwickelte Feldmodell beschrieben und seine einzelnen Module mit ihren mathematischen und physikalischen Grundlagen vorgestellt. Im Anschluss werden erste Ergebnisse fuer die Berechnung einer Diffusionsflamme aufgezeigt. (orig./GL)

  7. RadNet Air Quality (Deployable) Data

    U.S. Environmental Protection Agency — RadNet Deployable Monitoring is designed to collect radiological and meteorological information and data asset needed to establish the impact of radiation levels on...

  8. Digital radiation monitor system

    Quan Jinhu; Zhai Yongchun; Guan Junfeng; Ren Dangpei; Ma Zhiyuan

    2003-01-01

    The article introduced digital radiation monitor system. The contents include: how to use advanced computer net technology to establish equipment net for nuclear facility, how to control and manage measuring instruments on field equipment net by local area net, how to manage and issue radiation monitoring data by internet

  9. Simulation of bulk aerosol direct radiative effects and its climatic feedbacks in South Africa using RegCM4

    Tesfaye, M.; Botai, J.; Sivakumar, V.; Mengistu Tsidu, G.; Rautenbach, C. J. deW.; Moja, Shadung J.

    2016-05-01

    In this study, 12 year runs of the Regional Climate Model (RegCM4) have been used to analyze the bulk aerosol radiative effects and its climatic feedbacks in South Africa. Due to the geographical locations where the aerosol potential source regions are situated and the regional dynamics, the South African aerosol spatial-distribution has a unique feature. Across the west and southwest areas, desert dust particles are dominant. However, sulfate and carbonaceous aerosols are primarily distributed over the east and northern regions of the country. Analysis of the Radiative Effects (RE) shows that in South Africa the bulk aerosols play a role in reducing the net radiation absorbed by the surface via enhancing the net radiative heating in the atmosphere. Hence, across all seasons, the bulk aerosol-radiation-climate interaction induced statistically significant positive feedback on the net atmospheric heating rate. Over the western and central parts of South Africa, the overall radiative feedbacks of bulk aerosol predominantly induces statistically significant Cloud Cover (CC) enhancements. Whereas, over the east and southeast coastal areas, it induces minimum reductions in CC. The CC enhancement and RE of aerosols jointly induce radiative cooling at the surface which in turn results in the reduction of Surface Temperature (ST: up to -1 K) and Surface Sensible Heat Flux (SSHF: up to -24 W/m2). The ST and SSHF decreases cause a weakening of the convectively driven turbulences and surface buoyancy fluxes which lead to the reduction of the boundary layer height, surface pressure enhancement and dynamical changes. Throughout the year, the maximum values of direct and semi-direct effects of bulk aerosol were found in areas of South Africa which are dominated by desert dust particles. This signals the need for a strategic regional plan on how to reduce the dust production and monitoring of the dust dispersion as well as it initiate the need of further research on different

  10. Prototyping and validating requirements of radiation and nuclear emergency plan simulator

    Hamid, AHA., E-mail: amyhamijah@nm.gov.my [Malaysian Nuclear Agency (NM), Bangi, 43000 Kajang, Selangor (Malaysia); Faculty of Computing, Universiti Teknologi Malaysia (UTM), Skudai, 81310 Johor Bahru, Johor (Malaysia); Rozan, MZA.; Ibrahim, R.; Deris, S.; Selamat, A. [Faculty of Computing, Universiti Teknologi Malaysia (UTM), Skudai, 81310 Johor Bahru, Johor (Malaysia)

    2015-04-29

    Organizational incapability in developing unrealistic, impractical, inadequate and ambiguous mechanisms of radiological and nuclear emergency preparedness and response plan (EPR) causing emergency plan disorder and severe disasters. These situations resulting from 65.6% of poor definition and unidentified roles and duties of the disaster coordinator. Those unexpected conditions brought huge aftermath to the first responders, operators, workers, patients and community at large. Hence, in this report, we discuss prototyping and validating of Malaysia radiation and nuclear emergency preparedness and response plan simulation model (EPRM). A prototyping technique was required to formalize the simulation model requirements. Prototyping as systems requirements validation was carried on to endorse the correctness of the model itself against the stakeholder’s intensions in resolving those organizational incapability. We have made assumptions for the proposed emergency preparedness and response model (EPRM) through the simulation software. Those assumptions provided a twofold of expected mechanisms, planning and handling of the respective emergency plan as well as in bringing off the hazard involved. This model called RANEPF (Radiation and Nuclear Emergency Planning Framework) simulator demonstrated the training emergency response perquisites rather than the intervention principles alone. The demonstrations involved the determination of the casualties’ absorbed dose range screening and the coordination of the capacity planning of the expected trauma triage. Through user-centred design and sociotechnical approach, RANEPF simulator was strategized and simplified, though certainly it is equally complex.

  11. Solar panel thermal cycling testing by solar simulation and infrared radiation methods

    Nuss, H. E.

    1980-01-01

    For the solar panels of the European Space Agency (ESA) satellites OTS/MAROTS and ECS/MARECS the thermal cycling tests were performed by using solar simulation methods. The performance data of two different solar simulators used and the thermal test results are described. The solar simulation thermal cycling tests for the ECS/MARECS solar panels were carried out with the aid of a rotatable multipanel test rig by which simultaneous testing of three solar panels was possible. As an alternative thermal test method, the capability of an infrared radiation method was studied and infrared simulation tests for the ultralight panel and the INTELSAT 5 solar panels were performed. The setup and the characteristics of the infrared radiation unit using a quartz lamp array of approx. 15 sq and LN2-cooled shutter and the thermal test results are presented. The irradiation uniformity, the solar panel temperature distribution, temperature changing rates for both test methods are compared. Results indicate the infrared simulation is an effective solar panel thermal testing method.

  12. Prototyping and validating requirements of radiation and nuclear emergency plan simulator

    Hamid, AHA.; Rozan, MZA.; Ibrahim, R.; Deris, S.; Selamat, A.

    2015-01-01

    Organizational incapability in developing unrealistic, impractical, inadequate and ambiguous mechanisms of radiological and nuclear emergency preparedness and response plan (EPR) causing emergency plan disorder and severe disasters. These situations resulting from 65.6% of poor definition and unidentified roles and duties of the disaster coordinator. Those unexpected conditions brought huge aftermath to the first responders, operators, workers, patients and community at large. Hence, in this report, we discuss prototyping and validating of Malaysia radiation and nuclear emergency preparedness and response plan simulation model (EPRM). A prototyping technique was required to formalize the simulation model requirements. Prototyping as systems requirements validation was carried on to endorse the correctness of the model itself against the stakeholder’s intensions in resolving those organizational incapability. We have made assumptions for the proposed emergency preparedness and response model (EPRM) through the simulation software. Those assumptions provided a twofold of expected mechanisms, planning and handling of the respective emergency plan as well as in bringing off the hazard involved. This model called RANEPF (Radiation and Nuclear Emergency Planning Framework) simulator demonstrated the training emergency response perquisites rather than the intervention principles alone. The demonstrations involved the determination of the casualties’ absorbed dose range screening and the coordination of the capacity planning of the expected trauma triage. Through user-centred design and sociotechnical approach, RANEPF simulator was strategized and simplified, though certainly it is equally complex

  13. Prototyping and validating requirements of radiation and nuclear emergency plan simulator

    Hamid, AHA.; Rozan, MZA.; Ibrahim, R.; Deris, S.; Selamat, A.

    2015-04-01

    Organizational incapability in developing unrealistic, impractical, inadequate and ambiguous mechanisms of radiological and nuclear emergency preparedness and response plan (EPR) causing emergency plan disorder and severe disasters. These situations resulting from 65.6% of poor definition and unidentified roles and duties of the disaster coordinator. Those unexpected conditions brought huge aftermath to the first responders, operators, workers, patients and community at large. Hence, in this report, we discuss prototyping and validating of Malaysia radiation and nuclear emergency preparedness and response plan simulation model (EPRM). A prototyping technique was required to formalize the simulation model requirements. Prototyping as systems requirements validation was carried on to endorse the correctness of the model itself against the stakeholder's intensions in resolving those organizational incapability. We have made assumptions for the proposed emergency preparedness and response model (EPRM) through the simulation software. Those assumptions provided a twofold of expected mechanisms, planning and handling of the respective emergency plan as well as in bringing off the hazard involved. This model called RANEPF (Radiation and Nuclear Emergency Planning Framework) simulator demonstrated the training emergency response perquisites rather than the intervention principles alone. The demonstrations involved the determination of the casualties' absorbed dose range screening and the coordination of the capacity planning of the expected trauma triage. Through user-centred design and sociotechnical approach, RANEPF simulator was strategized and simplified, though certainly it is equally complex.

  14. REIONIZATION ON LARGE SCALES. I. A PARAMETRIC MODEL CONSTRUCTED FROM RADIATION-HYDRODYNAMIC SIMULATIONS

    Battaglia, N.; Trac, H.; Cen, R.; Loeb, A.

    2013-01-01

    We present a new method for modeling inhomogeneous cosmic reionization on large scales. Utilizing high-resolution radiation-hydrodynamic simulations with 2048 3 dark matter particles, 2048 3 gas cells, and 17 billion adaptive rays in a L = 100 Mpc h –1 box, we show that the density and reionization redshift fields are highly correlated on large scales (∼> 1 Mpc h –1 ). This correlation can be statistically represented by a scale-dependent linear bias. We construct a parametric function for the bias, which is then used to filter any large-scale density field to derive the corresponding spatially varying reionization redshift field. The parametric model has three free parameters that can be reduced to one free parameter when we fit the two bias parameters to simulation results. We can differentiate degenerate combinations of the bias parameters by combining results for the global ionization histories and correlation length between ionized regions. Unlike previous semi-analytic models, the evolution of the reionization redshift field in our model is directly compared cell by cell against simulations and performs well in all tests. Our model maps the high-resolution, intermediate-volume radiation-hydrodynamic simulations onto lower-resolution, larger-volume N-body simulations (∼> 2 Gpc h –1 ) in order to make mock observations and theoretical predictions

  15. Simulation of decay processes and radiation transport times in radioactivity measurements

    García-Toraño, E., E-mail: e.garciatorano@ciemat.es [Laboratorio de Metrología de Radiaciones Ionizantes, CIEMAT, Avda. Complutense 22, 28040 Madrid (Spain); Peyres, V. [Laboratorio de Metrología de Radiaciones Ionizantes, CIEMAT, Avda. Complutense 22, 28040 Madrid (Spain); Bé, M.-M.; Dulieu, C.; Lépy, M.-C. [CEA, LIST, Laboratoire National Henri Becquerel (LNE-LNHB), Bldg 602, PC111, 91191 Gif-sur-Yvette Cedex (France); Salvat, F. [Facultat de Física (FQA and ICC), Universitat de Barcelona, Diagonal 647, 08028 Barcelona (Spain)

    2017-04-01

    The Fortran subroutine package PENNUC, which simulates random decay pathways of radioactive nuclides, is described. The decay scheme of the active nuclide is obtained from the NUCLEIDE database, whose web application has been complemented with the option of exporting nuclear decay data (possible nuclear transitions, branching ratios, type and energy of emitted particles) in a format that is readable by the simulation subroutines. In the case of beta emitters, the initial energy of the electron or positron is sampled from the theoretical Fermi spectrum. De-excitation of the atomic electron cloud following electron capture and internal conversion is described using transition probabilities from the LLNL Evaluated Atomic Data Library and empirical or calculated energies of released X rays and Auger electrons. The time evolution of radiation showers is determined by considering the lifetimes of nuclear and atomic levels, as well as radiation propagation times. Although PENNUC is designed to operate independently, here it is used in conjunction with the electron-photon transport code PENELOPE, and both together allow the simulation of experiments with radioactive sources in complex material structures consisting of homogeneous bodies limited by quadric surfaces. The reliability of these simulation tools is demonstrated through comparisons of simulated and measured energy spectra from radionuclides with complex multi-gamma spectra, nuclides with metastable levels in their decay pathways, nuclides with two daughters, and beta plus emitters.

  16. Computer simulation for synchrotron radiation based X-ray fluorescent microtomography

    Deng Biao; Yu Xiaohan; Xu Hongjie

    2007-01-01

    Synchrotron radiation based fluorescent microtomography (SR-XFMT) is a nondestructive technique for detecting elemental composition and distribution inside a specimen with high spatial resolution and sensitivity, and will be an optional experimental technique at SSRF hard X-ray micro-focusing beamline now under construction. In this paper, the principles and developments of SR-XFMT are briefly introduced. Computer simulation of SR-XFMT experiment is performed. The image of the simulated sample is reconstructed using Filtered Back Projection (FBP), Algebraic Reconstruction Techniques (ART) and modified FBP with absorption correction. The qualities of the reconstructed images are analyzed and compared. The validity of these reconstruction techniques is discussed. (authors)

  17. How Models Simulate the Radiative Effect in the Transition Zone of the Aerosol-Cloud Continuum

    Calbo Angrill, J.; González, J. A.; Long, C. N.; McComiskey, A. C.

    2017-12-01

    Several studies have pointed towards dealing with clouds and aerosols as two manifestations of what is essentially the same physical phenomenon: a suspension of tiny particles in the air. Although the two extreme cases (i.e., pure aerosol and well-defined cloud) are easily distinguished, and obviously produce different radiative effects, there are many situations in the transition (or "twilight") zone. In a recent paper [Calbó et al., Atmos. Res. 2017, j.atmosres.2017.06.010], the authors of the current communication estimated that about 10% of time there might be a suspension of particles in the air that is difficult to distinguish as either cloud or aerosol. Radiative transfer models, however, simulate the effect of clouds and aerosols with different modules, routines, or parameterizations. In this study, we apply a sensitivity analysis approach to assess the ability of two radiative transfer models (SBDART and RRTM) in simulating the radiative effect of a suspension of particles with characteristics in the boundary between cloud and aerosol. We simulate this kind of suspension either in "cloud mode" or in "aerosol mode" and setting different values of optical depth, droplet size, water path, aerosol type, cloud height, etc. Irradiances both for solar and infrared bands are studied, both at ground level and at the top of the atmosphere, and all analyses are repeated for different solar zenith angles. We obtain that (a) water clouds and ice clouds have similar radiative effects if they have the same optical depth; (b) the spread of effects regarding different aerosol type/aerosol characteristics is remarkable; (c) radiative effects of an aerosol layer and of a cloud layer are different, even if they have similar optical depth; (d) for a given effect on the diffuse component, the effect on the direct component is usually greater (more extinction of direct beam) by aerosols than by clouds; (e) radiative transfer models are somewhat limited when simulating the

  18. Impacts of radiation exposure on the experimental microbial ecosystem: a particle-based model simulation approach

    Doi, M.; Tanaka, N.; Fuma, S.; Kawabata, Z.

    2004-01-01

    Well-designed experimental model ecosystem could be a simple reference of the actual environment and complex ecological systems. For ecological toxicity test of radiation and other environmental toxicants, we investigated and aquatic microbial ecosystem (closed microcosm) in the test tube with initial substrates,autotroph flagellate algae (Euglena, G.), heterotroph ciliate protozoa (Tetrahymena T.) and saprotroph bacteria (E, coli). These species organizes by itself to construct the ecological system, that keeps the sustainable population dynamics for more than 2 years after inoculation only by adding light diurnally and controlling temperature at 25 degree Celsius. Objective of the study is to develop the particle-based computer simulation by reviewing interactions among microbes and environment, and analyze the ecological toxicities of radiation on the microcosm by replicating experimental results in the computer simulation. (Author) 14 refs

  19. Peculiarities of approximation for reactor neutron energy spectra during computerized simulation of radiation defects

    Kupchishin, A.A.; Kupchishin, A.I.; Stusik, G.; Omarbekova, Zh.

    2001-01-01

    Peculiarities of approximation for reactor neutron energy spectra during radiation defects computerized simulation were discussed. Approximation of neutron spectra N(E) was carried out by N(E)=α·exp(-β·E)·sh(γ·E) formula (1), where α, β, γ - approximation coefficients. In the capacity of operating reactor data experimental data on 235 U and 239 Pu were applied. The algorithm was designed, and acting soft ware for spectra parameters calculation was developed. The following values of approximation parameters were obtained: α=80.8; β=0.935;γ=2.04 (for uranium and plutonium these coefficients are less distinguishing). Then with use of formula 1 and α, β, γ coefficients the approximation curves were constructed. These curves satisfactorily describe existing experimental data and allowing to use its for radiation defects simulation in the reactor materials

  20. Simulation Study of Discharging PCM Ceiling Panels through Night - time Radiative Cooling

    Bourdakis, Eleftherios; Kazanci, Ongun Berk; Grossule, F.

    2016-01-01

    demand. In the present simulation study, the coupling of nighttime radiative cooling with PCM for cooling an office room was investigated. For cooling water through nighttime radiative cooling two types of solar panels were utilized, an unglazed solar collector and photovoltaic/thermal (PV/T) panels...... provided by the PV/T panels was 43 W/m2 for Copenhagen, while for Milan and Athens it was 36 W/m2 and 34 W/m2, respectively. The cooling power of the unglazed solar collector was negligible. Finally, the total electricity produced in Copenhagen for the simulated period was 371 kWh, while for Milan...... and increase use of renewable energy sources. The aim is that by 2020 all new buildings should be nearly zero-energy buildings. A solution that could contribute to this is the combination of photovoltaic panels for the production of electricity and phase change material (PCM) for the reduction of peak cooling...

  1. A Simulation Study of the Radiation-Induced Bystander Effect: Modeling with Stochastically Defined Signal Reemission

    Kohei Sasaki

    2012-01-01

    Full Text Available The radiation-induced bystander effect (RIBE has been experimentally observed for different types of radiation, cell types, and cell culture conditions. However, the behavior of signal transmission between unirradiated and irradiated cells is not well known. In this study, we have developed a new model for RIBE based on the diffusion of soluble factors in cell cultures using a Monte Carlo technique. The model involves the signal emission probability from bystander cells following Poisson statistics. Simulations with this model show that the spatial configuration of the bystander cells agrees well with that of corresponding experiments, where the optimal emission probability is estimated through a large number of simulation runs. It was suggested that the most likely probability falls within 0.63–0.92 for mean number of the emission signals ranging from 1.0 to 2.5.

  2. A hybrid transport-diffusion Monte Carlo method for frequency-dependent radiative-transfer simulations

    Densmore, Jeffery D.; Thompson, Kelly G.; Urbatsch, Todd J.

    2012-01-01

    Discrete Diffusion Monte Carlo (DDMC) is a technique for increasing the efficiency of Implicit Monte Carlo radiative-transfer simulations in optically thick media. In DDMC, particles take discrete steps between spatial cells according to a discretized diffusion equation. Each discrete step replaces many smaller Monte Carlo steps, thus improving the efficiency of the simulation. In this paper, we present an extension of DDMC for frequency-dependent radiative transfer. We base our new DDMC method on a frequency-integrated diffusion equation for frequencies below a specified threshold, as optical thickness is typically a decreasing function of frequency. Above this threshold we employ standard Monte Carlo, which results in a hybrid transport-diffusion scheme. With a set of frequency-dependent test problems, we confirm the accuracy and increased efficiency of our new DDMC method.

  3. Accelerator simulation and theoretical modelling of radiation effects (SMoRE)

    2018-01-01

    This publication summarizes the findings and conclusions of the IAEA coordinated research project (CRP) on accelerator simulation and theoretical modelling of radiation effects, aimed at supporting Member States in the development of advanced radiation-resistant structural materials for implementation in innovative nuclear systems. This aim can be achieved through enhancement of both experimental neutron-emulation capabilities of ion accelerators and improvement of the predictive efficiency of theoretical models and computer codes. This dual approach is challenging but necessary, because outputs of accelerator simulation experiments need adequate theoretical interpretation, and theoretical models and codes need high dose experimental data for their verification. Both ion irradiation investigations and computer modelling have been the specific subjects of the CRP, and the results of these studies are presented in this publication which also includes state-ofthe- art reviews of four major aspects of the project...

  4. Implementation of Radiation, Ablation, and Free Energy Minimization Modules for Coupled Simulations of Hypersonic Flow

    Gnoffo, Peter A.; Johnston, Christopher O.; Thompson, Richard A.

    2009-01-01

    A description of models and boundary conditions required for coupling radiation and ablation physics to a hypersonic flow simulation is provided. Chemical equilibrium routines for varying elemental mass fraction are required in the flow solver to integrate with the equilibrium chemistry assumption employed in the ablation models. The capability also enables an equilibrium catalytic wall boundary condition in the non-ablating case. The paper focuses on numerical implementation issues using FIRE II, Mars return, and Apollo 4 applications to provide context for discussion. Variable relaxation factors applied to the Jacobian elements of partial equilibrium relations required for convergence are defined. Challenges of strong radiation coupling in a shock capturing algorithm are addressed. Results are presented to show how the current suite of models responds to a wide variety of conditions involving coupled radiation and ablation.

  5. 2D radiation-magnetohydrodynamic simulations of SATURN imploding Z-pinches

    Hammer, J.H.; Eddleman, J.L.; Springer, P.T.

    1995-01-01

    Z-pinch implosions driven by the SATURN device at Sandia National Laboratory are modeled with a 2D radiation magnetohydrodynamic (MHD) code, showing strong growth of magneto-Rayleigh Taylor (MRT) instability. Modeling of the linear and nonlinear development of MRT modes predicts growth of bubble-spike structures that increase the time span of stagnation and the resulting x-ray pulse width. Radiation is important in the pinch dynamics keeping the sheath relatively cool during the run-in and releasing most of the stagnation energy. The calculations give x-ray pulse widths and magnitudes in reasonable agreement with experiments, but predict a radiating region that is too dense and radially localized at stagnation. We also consider peaked initial density profiles with constant imploding sheath velocity that should reduce MRT instability and improve performance. 2D krypton simulations show an output x-ray power > 80 TW for the peaked profile

  6. Laboratory simulation of interplanetary ultraviolet radiation (broad spectrum) and its effects on Deinococcus radiodurans

    Paulino-Lima, Ivan Gláucio; Pilling, Sérgio; Janot-Pacheco, Eduardo; de Brito, Arnaldo Naves; Barbosa, João Alexandre Ribeiro Gonçalves; Leitão, Alvaro Costa; Lage, Claudia de Alencar Santos

    2010-08-01

    The radiation-resistant bacterium Deinococcus radiodurans was exposed to a simulated interplanetary UV radiation at the Brazilian Synchrotron Light Laboratory (LNLS). Bacterial samples were irradiated on different substrates to investigate the influence of surface relief on cell survival. The effects of cell multi-layers were also investigated. The ratio of viable microorganisms remained virtually the same (average 2%) for integrated doses from 1.2 to 12 kJ m -2, corresponding to 16 h of irradiation at most. The asymptotic profiles of the curves, clearly connected to a shielding effect provided by multi-layering cells on a cavitary substrate (carbon tape), means that the inactivation rate may not change significantly along extended periods of exposure to radiation. Such high survival rates reinforce the possibility of an interplanetary transfer of viable microbes.

  7. Comparative study of structural properties of trehalose water solutions by neutron diffraction, synchrotron radiation and simulation

    Cesaro, A.; Magazu, V.; Migliardo, F.; Sussich, F.; Vadala, M

    2004-07-15

    Neutron diffraction measurements combined with H/D substitution have been performed on trehalose aqueous solutions as a function of temperature and concentration by using the SANDALS diffractometer at ISIS Facility (UK). The findings point out a high capability of trehalose to strongly affect the tetrahedral hydrogen bond network of water. The neutron diffraction results are also compared with simulation and experimental data obtained by synchrotron radiation on the phospholipid bilayer membranes (DPPC)/trehalose/H{sub 2}O ternary system.

  8. Simulation of the accumulation kinetics for radiation point defects in a metals with impurity

    Iskakov, B.M.; Nurova, A.B.

    2001-01-01

    In the work a kinetics of vacancies (V) and interstitial atoms (IA) accumulation for cases when the V and IA are recombining with each other, absorbing by drain and capturing by impurity atoms has been simulated. The differential equations system numerical solution was carried out by the Runge-Kutta method. The dynamical equilibrium time achievement for the point radiation defects accumulation process in the metal with impurity is considered

  9. Monte Carlo 2000 Conference : Advanced Monte Carlo for Radiation Physics, Particle Transport Simulation and Applications

    Baräo, Fernando; Nakagawa, Masayuki; Távora, Luis; Vaz, Pedro

    2001-01-01

    This book focusses on the state of the art of Monte Carlo methods in radiation physics and particle transport simulation and applications, the latter involving in particular, the use and development of electron--gamma, neutron--gamma and hadronic codes. Besides the basic theory and the methods employed, special attention is paid to algorithm development for modeling, and the analysis of experiments and measurements in a variety of fields ranging from particle to medical physics.

  10. Monte Carlo simulations for the space radiation superconducting shield project (SR2S).

    Vuolo, M; Giraudo, M; Musenich, R; Calvelli, V; Ambroglini, F; Burger, W J; Battiston, R

    2016-02-01

    Astronauts on deep-space long-duration missions will be exposed for long time to galactic cosmic rays (GCR) and Solar Particle Events (SPE). The exposure to space radiation could lead to both acute and late effects in the crew members and well defined countermeasures do not exist nowadays. The simplest solution given by optimized passive shielding is not able to reduce the dose deposited by GCRs below the actual dose limits, therefore other solutions, such as active shielding employing superconducting magnetic fields, are under study. In the framework of the EU FP7 SR2S Project - Space Radiation Superconducting Shield--a toroidal magnetic system based on MgB2 superconductors has been analyzed through detailed Monte Carlo simulations using Geant4 interface GRAS. Spacecraft and magnets were modeled together with a simplified mechanical structure supporting the coils. Radiation transport through magnetic fields and materials was simulated for a deep-space mission scenario, considering for the first time the effect of secondary particles produced in the passage of space radiation through the active shielding and spacecraft structures. When modeling the structures supporting the active shielding systems and the habitat, the radiation protection efficiency of the magnetic field is severely decreasing compared to the one reported in previous studies, when only the magnetic field was modeled around the crew. This is due to the large production of secondary radiation taking place in the material surrounding the habitat. Copyright © 2016 The Committee on Space Research (COSPAR). Published by Elsevier Ltd. All rights reserved.

  11. On physical and numerical instabilities arising in simulations of non-stationary radiatively cooling shocks

    Badjin, D. A.; Glazyrin, S. I.; Manukovskiy, K. V.; Blinnikov, S. I.

    2016-06-01

    We describe our modelling of the radiatively cooling shocks and their thin shells with various numerical tools in different physical and calculational setups. We inspect structure of the dense shell, its formation and evolution, pointing out physical and numerical factors that sustain its shape and also may lead to instabilities. We have found that under certain physical conditions, the circular shaped shells show a strong bending instability and successive fragmentation on Cartesian grids soon after their formation, while remain almost unperturbed when simulated on polar meshes. We explain this by physical Rayleigh-Taylor-like instabilities triggered by corrugation of the dense shell surfaces by numerical noise. Conditions for these instabilities follow from both the shell structure itself and from episodes of transient acceleration during re-establishing of dynamical pressure balance after sudden radiative cooling onset. They are also easily excited by physical perturbations of the ambient medium. The widely mentioned non-linear thin shell instability, in contrast, in tests with physical perturbations is shown to have only limited chances to develop in real radiative shocks, as it seems to require a special spatial arrangement of fluctuations to be excited efficiently. The described phenomena also set new requirements on further simulations of the radiatively cooling shocks in order to be physically correct and free of numerical artefacts.

  12. Quantitative comparisons between experimentally measured 2-D carbon radiation and Monte Carlo impurity (MCI) code simulations

    Evans, T.E.; Leonard, A.W.; West, W.P.; Finkenthal, D.F.; Fenstermacher, M.E.; Porter, G.D.

    1998-08-01

    Experimentally measured carbon line emissions and total radiated power distributions from the DIII-D divertor and Scrape-Off Layer (SOL) are compared to those calculated with the Monte Carlo Impurity (MCI) model. A UEDGE background plasma is used in MCI with the Roth and Garcia-Rosales (RG-R) chemical sputtering model and/or one of six physical sputtering models. While results from these simulations do not reproduce all of the features seen in the experimentally measured radiation patterns, the total radiated power calculated in MCI is in relatively good agreement with that measured by the DIII-D bolometric system when the Smith78 physical sputtering model is coupled to RG-R chemical sputtering in an unaltered UEDGE plasma. Alternatively, MCI simulations done with UEDGE background ion temperatures along the divertor target plates adjusted to better match those measured in the experiment resulted in three physical sputtering models which when coupled to the RG-R model gave a total radiated power that was within 10% of measured value

  13. Development of a space radiation Monte Carlo computer simulation based on the FLUKA and ROOT codes

    Pinsky, L; Ferrari, A; Sala, P; Carminati, F; Brun, R

    2001-01-01

    This NASA funded project is proceeding to develop a Monte Carlo-based computer simulation of the radiation environment in space. With actual funding only initially in place at the end of May 2000, the study is still in the early stage of development. The general tasks have been identified and personnel have been selected. The code to be assembled will be based upon two major existing software packages. The radiation transport simulation will be accomplished by updating the FLUKA Monte Carlo program, and the user interface will employ the ROOT software being developed at CERN. The end-product will be a Monte Carlo-based code which will complement the existing analytic codes such as BRYNTRN/HZETRN presently used by NASA to evaluate the effects of radiation shielding in space. The planned code will possess the ability to evaluate the radiation environment for spacecraft and habitats in Earth orbit, in interplanetary space, on the lunar surface, or on a planetary surface such as Mars. Furthermore, it will be usef...

  14. CFD simulations and reduced order modeling of a refrigerator compartment including radiation effects

    Bayer, Ozgur; Oskay, Ruknettin; Paksoy, Akin; Aradag, Selin

    2013-01-01

    Highlights: ► Free convection in a refrigerator is simulated including radiation effects. ► Heat rates are affected drastically when radiation effects are considered. ► 95% of the flow energy can be represented by using one spatial POD mode. - Abstract: Considering the engineering problem of natural convection in domestic refrigerator applications, this study aims to simulate the fluid flow and temperature distribution in a single commercial refrigerator compartment by using the experimentally determined temperature values as the specified constant wall temperature boundary conditions. The free convection in refrigerator applications is evaluated as a three-dimensional (3D), turbulent, transient and coupled non-linear flow problem. Radiation heat transfer mode is also included in the analysis. According to the results, taking radiation effects into consideration does not change the temperature distribution inside the refrigerator significantly; however the heat rates are affected drastically. The flow inside the compartment is further analyzed with a reduced order modeling method called Proper Orthogonal Decomposition (POD) and the energy contents of several spatial and temporal modes that exist in the flow are examined. The results show that approximately 95% of all the flow energy can be represented by only using one spatial mode

  15. Effect of incident beam and diffuse radiation on par absorption, photosynthesis and transpiration of sitka spruce - a simulation study

    Wang, Y.P.; Jarvis, P.G.

    1990-01-01

    A simulation model, Maestro, is used to study the influence of beam fraction in the incident radiation and the radiance distribution of the sky diffuse radiation on PAR absorption, photosynthesis and transpiration of a Sitka spruce (Picea sitchensis (Bong.) Carr) tree crown. It is concluded that inaccurate separation of beam and diffuse radiation leads to significant errors in estimating the amounts of PAR absorbed, photosynthesis and transpiration by a tree in the stand. Much more attention should be paid to adequate descriptions of the radiance distribution of the sky diffuse radiation under different sky conditions. A useful approach is proposed for simulating the incident global radiaiton in a physiological, process-based model

  16. Theory and validation of a liquid radiation filter greenhouse simulation for performance prediction

    Feuermann, D.; Kopel, R.; Zeroni, M.; Levi, S.; Gale, J.

    1997-01-01

    A greenhouse is described which has a selectively absorbing liquid radiation filter (LRF) circulating in double layered cladding. The filter removes much of the near infrared wave band of solar radiation (700 nm) while transmitting most of the photosynthetic radiation (400-700 nm). This greatly reduces the heat input to the greenhouse and, by transferring heat from day to night, facilitates better temperature control. This is particularly important for CO2 fertilization, which requires that the greenhouse should remain closed during daylight hours. A computer simulation model was developed to study the relationship between design parameters of such a LRF greenhouse and its thermal performance under different climatic conditions. The model was based on a small number of governing equations describing the major physical phenomena responsible for the greenhouse climate. Validation of the simulation was performed with data from a 330 m2 LRF greenhouse, operating in the Negev (Israel) desert highlands. The predicted greenhouse temperatures were found to agree with measured values to within one to two degrees Celsius. Performances of a LRF and a conventional greenhouse were compared using the simulation and hourly meteorological data for central Israel. For the summer season of May to October, the number of daylight hours during which the LRF greenhouse could remain closed was larger by about two-thirds than that of the conventional greenhouse

  17. Stratospheric sulfur and its implications for radiative forcing simulated by the chemistry climate model EMAC.

    Brühl, C; Lelieveld, J; Tost, H; Höpfner, M; Glatthor, N

    2015-03-16

    Multiyear simulations with the atmospheric chemistry general circulation model EMAC with a microphysical modal aerosol module at high vertical resolution demonstrate that the sulfur gases COS and SO 2 , the latter from low-latitude and midlatitude volcanic eruptions, predominantly control the formation of stratospheric aerosol. Marine dimethyl sulfide (DMS) and other SO 2 sources, including strong anthropogenic emissions in China, are found to play a minor role except in the lowermost stratosphere. Estimates of volcanic SO 2 emissions are based on satellite observations using Total Ozone Mapping Spectrometer and Ozone Monitoring Instrument for total injected mass and Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) on Envisat or Stratospheric Aerosol and Gases Experiment for the spatial distribution. The 10 year SO 2 and COS data set of MIPAS is also used for model evaluation. The calculated radiative forcing of stratospheric background aerosol including sulfate from COS and small contributions by DMS oxidation, and organic aerosol from biomass burning, is about 0.07W/m 2 . For stratospheric sulfate aerosol from medium and small volcanic eruptions between 2005 and 2011 a global radiative forcing up to 0.2W/m 2 is calculated, moderating climate warming, while for the major Pinatubo eruption the simulated forcing reaches 5W/m 2 , leading to temporary climate cooling. The Pinatubo simulation demonstrates the importance of radiative feedback on dynamics, e.g., enhanced tropical upwelling, for large volcanic eruptions.

  18. Conceptual Design of Simulated Radiation Detector for Nuclear Forensics Exercise Purposes

    Kim, Jae Kwang; Baek, Ye Ji; Lee, Seung Min [Korea Institute of Nuclear Non-proliferation and Control, Daejeon (Korea, Republic of)

    2016-05-15

    A site associated with an illicit trafficking or security event may contain trace evidence of criminal or malicious acts involving radioactive material. Such a site is called a radiological crime scene. Management of a radiological crime scene requires a process of ensuring an orderly accurate and effective collection and preservation of evidence. In order to effectively address such a security event, first responders and/or on-scene investigators need to exercise detecting, locating and recovering materials at the scene of the incident. During such the exercise, a sealed source can be used. This source is allowed to be a very small amount for exercises as there is the limit on the amount of radioactive material that causes no harm. So it is typically difficult to be found by some radiation detectors that the exercises have little effect on improving the ability of trainees. Therefore, we developed a conceptual design of a simulation radiation detector coupled with simulation sources which are designed to imitate a significant amount radioactive material for the purpose of a nuclear forensics exercise. With the potential of a terrorist attack using radioactive materials, the first responders should regularly perform the nuclear forensics exercise in order to prepare for a recovery operation. In this regard, some devices such as simulated detector, coupled with a virtual source, can replace a real detector and a surrogate source of material in field exercises. BLE technology could be applied to create similar environments to that of an actual radiological attack. The detector coupled with the simulated sources could be very helpful for first responders in testing and improving their ability in the case of a nuclear security event. In addition, this conceptual design could be extended to develop a simulated dosimeter coupled with a beacon signal emitters. The dosimeter is a personal device used for indicating the cumulated exposure of radiation in real time in the

  19. Conceptual Design of Simulated Radiation Detector for Nuclear Forensics Exercise Purposes

    Kim, Jae Kwang; Baek, Ye Ji; Lee, Seung Min

    2016-01-01

    A site associated with an illicit trafficking or security event may contain trace evidence of criminal or malicious acts involving radioactive material. Such a site is called a radiological crime scene. Management of a radiological crime scene requires a process of ensuring an orderly accurate and effective collection and preservation of evidence. In order to effectively address such a security event, first responders and/or on-scene investigators need to exercise detecting, locating and recovering materials at the scene of the incident. During such the exercise, a sealed source can be used. This source is allowed to be a very small amount for exercises as there is the limit on the amount of radioactive material that causes no harm. So it is typically difficult to be found by some radiation detectors that the exercises have little effect on improving the ability of trainees. Therefore, we developed a conceptual design of a simulation radiation detector coupled with simulation sources which are designed to imitate a significant amount radioactive material for the purpose of a nuclear forensics exercise. With the potential of a terrorist attack using radioactive materials, the first responders should regularly perform the nuclear forensics exercise in order to prepare for a recovery operation. In this regard, some devices such as simulated detector, coupled with a virtual source, can replace a real detector and a surrogate source of material in field exercises. BLE technology could be applied to create similar environments to that of an actual radiological attack. The detector coupled with the simulated sources could be very helpful for first responders in testing and improving their ability in the case of a nuclear security event. In addition, this conceptual design could be extended to develop a simulated dosimeter coupled with a beacon signal emitters. The dosimeter is a personal device used for indicating the cumulated exposure of radiation in real time in the

  20. Simulating and Detecting Radiation-Induced Errors for Onboard Machine Learning

    Wagstaff, Kiri L.; Bornstein, Benjamin; Granat, Robert; Tang, Benyang; Turmon, Michael

    2009-01-01

    Spacecraft processors and memory are subjected to high radiation doses and therefore employ radiation-hardened components. However, these components are orders of magnitude more expensive than typical desktop components, and they lag years behind in terms of speed and size. We have integrated algorithm-based fault tolerance (ABFT) methods into onboard data analysis algorithms to detect radiation-induced errors, which ultimately may permit the use of spacecraft memory that need not be fully hardened, reducing cost and increasing capability at the same time. We have also developed a lightweight software radiation simulator, BITFLIPS, that permits evaluation of error detection strategies in a controlled fashion, including the specification of the radiation rate and selective exposure of individual data structures. Using BITFLIPS, we evaluated our error detection methods when using a support vector machine to analyze data collected by the Mars Odyssey spacecraft. We found ABFT error detection for matrix multiplication is very successful, while error detection for Gaussian kernel computation still has room for improvement.

  1. Fire simulation in radioactive waste disposal and the radiation risk associated

    Domingos, Érica Nascimento

    2018-01-01

    An atmospheric dispersion of radioactive material is one of the possible consequences of an accident scenario in nuclear installations, radiative and radioactive waste deposit. Taking into account a possibility of this release of radioactive material into the atmosphere this work proposes a modeling of the atmospheric dispersion from a fire scenario in a deposit of radioactive waste of low and middle level of radiation varying the amount of inventory released in the fire. For this simulation was adopted the software of physical codes of medical health, the HotSpot Health Physics Codes which uses the Gaussian model to calculate an atmospheric dispersion based on the Pasquill atmospheric stability classes. This software calculates a total effective dose in relation to distance, such as a compromised dose in a list of specific organs, among them the lung, object of work study for calculating the risk of cancer associated with a low dose of radiation. The radiological risk calculation is held by the BEIR V model, Biological Effects of Ionizing Radiations, one of the models to estimate the relative risk of cancer induced by ionizing radiation. (author)

  2. Modelling the propagation of terahertz radiation through a tissue simulating phantom

    Walker, Gillian C; Berry, Elizabeth; Smye, Stephen W; Zinov'ev, Nick N; Fitzgerald, Anthony J; Miles, Robert E; Chamberlain, Martyn; Smith, Michael A

    2004-01-01

    Terahertz (THz) frequency radiation, 0.1 THz to 20 THz, is being investigated for biomedical imaging applications following the introduction of pulsed THz sources that produce picosecond pulses and function at room temperature. Owing to the broadband nature of the radiation, spectral and temporal information is available from radiation that has interacted with a sample; this information is exploited in the development of biomedical imaging tools and sensors. In this work, models to aid interpretation of broadband THz spectra were developed and evaluated. THz radiation lies on the boundary between regions best considered using a deterministic electromagnetic approach and those better analysed using a stochastic approach incorporating quantum mechanical effects, so two computational models to simulate the propagation of THz radiation in an absorbing medium were compared. The first was a thin film analysis and the second a stochastic Monte Carlo model. The Cole-Cole model was used to predict the variation with frequency of the physical properties of the sample and scattering was neglected. The two models were compared with measurements from a highly absorbing water-based phantom. The Monte Carlo model gave a prediction closer to experiment over 0.1 to 3 THz. Knowledge of the frequency-dependent physical properties, including the scattering characteristics, of the absorbing media is necessary. The thin film model is computationally simple to implement but is restricted by the geometry of the sample it can describe. The Monte Carlo framework, despite being initially more complex, provides greater flexibility to investigate more complicated sample geometries

  3. 2-D FEM Simulation of Propagation and Radiation of Leaky Lamb Wave in a Plate-Type Ultrasonic Waveguide Sensor

    Park, Sang-Jin; Kim, Hoe-Woong; Joo, Young-Sang; Kim, Sung-Kyun; Kim, Jong-Bum [KAERI, Daejeon (Korea, Republic of)

    2016-05-15

    This paper introduces the 2-D FEM simulation of the propagation and radiation of the leaky Lamb wave in and from a plate-type ultrasonic waveguide sensor conducted for the radiation beam profile analysis. The FEM simulations are performed with three different excitation frequencies and the radiation beam profiles obtained from FEM simulations are compared with those obtained from corresponding experiments. This paper deals with the 2-D FEM simulation of the propagation and radiation of the leaky Lamb wave in and from a plate-type ultrasonic waveguide sensor conducted to analyze the radiation beam profiles. The radiation beam profile results obtained from the FEM simulation show good agreement with the ones obtained from the experiment. This result will be utilized to improve the performance of the developed waveguide sensor. The quality of the visualized image is mainly affected by beam profile characteristics of the leaky wave radiated from the waveguide sensor. However, the relationships between the radiation beam profile and many parameters of the waveguide sensor are not fully revealed yet. Therefore, further parametric studies are necessary to improve the performance of the sensor and the finite element method (FEM) is one of the most effective tools for the parametric study.

  4. Molecular dynamics simulation on the formation and annihilation behaviors of radiation defects in Li2O

    Takuji Oda; Satoru Tanaka; Yasuhisa Oya

    2006-01-01

    The influence of radiation defects is one of the main factors that determine tritium release behavior from blanket breeding materials in fusion reactors. Classical molecular dynamics simulation (MD) is a powerful technique to investigate the radiation damage processes, because it can provide atomic-scale information on the defects. In this study, we conducted radiation simulation for Li 2 O using MD and analyzed formation and annihilation behaviors of radiation defects, as a fundamental research for radiation response of Li-containing oxides. Buckingham type two-body potential model was used. In order to remove the unphysical impulsive force at short inter-ionic distances in Buckingham model, each potential function was connected to that of the ZBL potential models at around 0.8 A. NEV ensemble was employed with the initial simulation temperature of 0 K. 10 x 10 x 10 supercell consisting of 4000 Li 2 O was used as a unit cell under 3D periodic boundary conditions. Radiation simulation was initiated by introducing an energy of a certain direction to an ion, as a displacement energy. The lowest displacement energy by which a defect was created and survived beyond 5 ps was regarded as the threshold energy. 42 and 21 displacement directions were surveyed for Li and O, respectively, based on the symmetry of the Li 2 O crystal. In both Li and O defect formations, [100] displacement shows significantly lower threshold energy than [111] displacement. Li defects were easily created than O defects almost in all directions. In fact, the average threshold energy except [111] displacement, which possesses extremely high threshold energy, was 21 eV for Li and 49 eV for O. In some cases, no defect could survive beyond 5 ps even by higher displacement energies than the threshold energy, due to the self-annealing effect. The self-annealing completed basically within 1 ps after introduction of displacement energy. At around this time, velocity distribution of all ions in the system

  5. Evaluation of high-fidelity simulation training in radiation oncology using an outcomes logic model

    Giuliani, Meredith; Gillan, Caitlin; Wong, Olive; Harnett, Nicole; Milne, Emily; Moseley, Doug; Thompson, Robert; Catton, Pamela; Bissonnette, Jean-Pierre

    2014-01-01

    To evaluate the feasibility and educational value of high-fidelity, interprofessional team-based simulation in radiation oncology. The simulation event was conducted in a radiation oncology department during a non-clinical day. It involved 5 simulation scenarios that were run over three 105 minute timeslots in a single day. High-acuity, low-frequency clinical situations were selected and included HDR brachytherapy emergency, 4D CT artifact management, pediatric emergency clinical mark-up, electron scalp trial set-up and a cone beam CT misregistration incident. A purposive sample of a minimum of 20 trainees was required to assess recruitment feasibility. A faculty radiation oncologist (RO), medical physicist (MP) or radiation therapist (RTT), facilitated each case. Participants completed a pre event survey of demographic data and motivation for participation. A post event survey collected perceptions of familiarity with the clinical content, comfort with interprofessional practice, and event satisfaction, scored on a 1–10 scale in terms of clinical knowledge, clinical decision making, clinical skills, exposure to other trainees and interprofessional communication. Means and standard deviations were calculated. Twenty-one trainees participated including 6 ROs (29%), 6 MPs (29%), and 9 RTTs (43%). All 12 cases (100%) were completed within the allocated 105 minutes. Nine faculty facilitators, (3MP, 2 RO, 4 RTTs) were required for 405 minutes each. Additional costs associated with this event were 154 hours to build the high fidelity scenarios, 2 standardized patients (SPs) for a total of 15.5 hours, and consumables.The mean (±SD) educational value score reported by participants with respect to clinical knowledge was 8.9 (1.1), clinical decision making 8.9 (1.3), clinical skills 8.9 (1.1), exposure to other trainees 9.1 (2.3) and interprofessional communication 9.1 (1.0). Fifteen (71%) participants reported the cases were of an appropriate complexity. The importance

  6. Premar-2: a Monte Carlo code for radiative transport simulation in atmospheric environments

    Cupini, E.

    1999-01-01

    The peculiarities of the PREMAR-2 code, aimed at radiation transport Monte Carlo simulation in atmospheric environments in the infrared-ultraviolet frequency range, are described. With respect to the previously developed PREMAR code, besides plane multilayers, spherical multilayers and finite sequences of vertical layers, each one with its own atmospheric behaviour, are foreseen in the new code, together with the refraction phenomenon, so that long range, highly slanted paths can now be more faithfully taken into account. A zenithal angular dependence of the albedo coefficient has moreover been introduced. Lidar systems, with spatially independent source and telescope, are allowed again to be simulated, and, in this latest version of the code, sensitivity analyses to be performed. According to this last feasibility, consequences on radiation transport of small perturbations in physical components of the atmospheric environment may be analyze and the related effects on searched results estimated. The availability of a library of physical data (reaction coefficients, phase functions and refraction indexes) is required by the code, providing the essential features of the environment of interest needed of the Monte Carlo simulation. Variance reducing techniques have been enhanced in the Premar-2 code, by introducing, for instance, a local forced collision technique, especially apt to be used in Lidar system simulations. Encouraging comparisons between code and experimental results carried out at the Brasimone Centre of ENEA, have so far been obtained, even if further checks of the code are to be performed [it

  7. Patient dose simulation in X-ray CT using a radiation treatment-planning system

    Nakae, Yasuo; Oda, Masahiko; Minamoto, Takahiro

    2003-01-01

    Medical irradiation dosage has been increasing with the development of new radiological equipment and new techniques like interventional radiology. It is fair to say that patient dose has been increased as a result of the development of multi-slice CT. A number of studies on the irradiation dose of CT have been reported, and the computed tomography dose index (CTDI) is now used as a general means of determining CT dose. However, patient dose distribution in the body varies with the patient's constitution, bowel gas in the body, and conditions of exposure. In this study, patient dose was analyzed from the viewpoint of dose distribution, using a radiation treatment-planning computer. Percent depth dose (PDD) and the off-center ratio (OCR) of the CT beam are needed to calculate dose distribution by the planning computer. Therefore, X-ray CT data were measured with various apparatuses, and beam data were sent to the planning computer. Measurement and simulation doses in the elliptical phantom (Mix-Dp: water equivalent material) were collated, and the CT irradiation dose was determined for patient dose simulation. The rotational radiation treatment technique was used to obtain the patient dose distribution of CT, and patient dose was evaluated through simulation of the dose distribution. CT images of the thorax were sent to the planning computer and simulated. The result was that the patient dose distribution of the thorax was obtained for CT examination. (author)

  8. A novel radiation detector for removing scattered radiation in chest radiography: Monte Carlo simulation-based performance evaluation

    Roh, Y. H.; Yoon, Y.; Kim, K.; Kim, J.; Kim, J.; Morishita, J.

    2016-10-01

    Scattered radiation is the main reason for the degradation of image quality and the increased patient exposure dose in diagnostic radiology. In an effort to reduce scattered radiation, a novel structure of an indirect flat panel detector has been proposed. In this study, a performance evaluation of the novel system in terms of image contrast as well as an estimation of the number of photons incident on the detector and the grid exposure factor were conducted using Monte Carlo simulations. The image contrast of the proposed system was superior to that of the no-grid system but slightly inferior to that of the parallel-grid system. The number of photons incident on the detector and the grid exposure factor of the novel system were higher than those of the parallel-grid system but lower than those of the no-grid system. The proposed system exhibited the potential for reduced exposure dose without image quality degradation; additionally, can be further improved by a structural optimization considering the manufacturer's specifications of its lead contents.

  9. Coloured Petri Nets

    Jensen, Kurt

    1987-01-01

    The author describes a Petri net model, called coloured Petri nets (CP-nets), by means of which it is possible to describe large systems without having to cope with unnecessary details. The author introduces CP-nets and provide a first impression of their modeling power and the suitability...

  10. Learning Visual Basic NET

    Liberty, Jesse

    2009-01-01

    Learning Visual Basic .NET is a complete introduction to VB.NET and object-oriented programming. By using hundreds of examples, this book demonstrates how to develop various kinds of applications--including those that work with databases--and web services. Learning Visual Basic .NET will help you build a solid foundation in .NET.

  11. DGR, GGR; molecular dynamical codes for simulating radiation damages in diamond and graphite crystals

    Taji, Yukichi

    1984-06-01

    Development has been made of molecular dynamical codes DGR and GGR to simulate radiation damages yielded in the diamond and graphite structure crystals, respectively. Though the usual molecular dynamical codes deal only with the central forces as the mutual interactions between atoms, the present codes can take account of noncentral forces to represent the effect of the covalent bonds characteristic of diamond or graphite crystals. It is shown that lattice defects yielded in these crystals are stable by themselves in the present method without any supports of virtual surface forces set on the crystallite surfaces. By this effect the behavior of lattice defects has become possible to be simulated in a more realistic manner. Some examples of the simulation with these codes are shown. (author)

  12. Python Radiative Transfer Emission code (PyRaTE): non-LTE spectral lines simulations

    Tritsis, A.; Yorke, H.; Tassis, K.

    2018-05-01

    We describe PyRaTE, a new, non-local thermodynamic equilibrium (non-LTE) line radiative transfer code developed specifically for post-processing astrochemical simulations. Population densities are estimated using the escape probability method. When computing the escape probability, the optical depth is calculated towards all directions with density, molecular abundance, temperature and velocity variations all taken into account. A very easy-to-use interface, capable of importing data from simulations outputs performed with all major astrophysical codes, is also developed. The code is written in PYTHON using an "embarrassingly parallel" strategy and can handle all geometries and projection angles. We benchmark the code by comparing our results with those from RADEX (van der Tak et al. 2007) and against analytical solutions and present case studies using hydrochemical simulations. The code will be released for public use.

  13. Nrf2 Activation Protects against Solar-Simulated Ultraviolet Radiation in Mice and Humans.

    Knatko, Elena V; Ibbotson, Sally H; Zhang, Ying; Higgins, Maureen; Fahey, Jed W; Talalay, Paul; Dawe, Robert S; Ferguson, James; Huang, Jeffrey T-J; Clarke, Rosemary; Zheng, Suqing; Saito, Akira; Kalra, Sukirti; Benedict, Andrea L; Honda, Tadashi; Proby, Charlotte M; Dinkova-Kostova, Albena T

    2015-06-01

    The transcription factor Nrf2 determines the ability to adapt and survive under conditions of electrophilic, oxidative, and inflammatory stress by regulating the expression of elaborate networks comprising nearly 500 genes encoding proteins with versatile cytoprotective functions. In mice, disruption of Nrf2 increases susceptibility to carcinogens and accelerates disease pathogenesis. Paradoxically, Nrf2 is upregulated in established human tumors, but whether this upregulation drives carcinogenesis is not known. Here we show that the incidence, multiplicity, and burden of solar-simulated UV radiation-mediated cutaneous tumors that form in SKH-1 hairless mice in which Nrf2 is genetically constitutively activated are lower than those that arise in their wild-type counterparts. Pharmacologic Nrf2 activation by topical biweekly applications of small (40 nmol) quantities of the potent bis(cyano enone) inducer TBE-31 has a similar protective effect against solar-simulated UV radiation in animals receiving long-term treatment with the immunosuppressive agent azathioprine. Genetic or pharmacologic Nrf2 activation lowers the expression of the pro-inflammatory factors IL6 and IL1β, and COX2 after acute exposure of mice to UV radiation. In healthy human subjects, topical applications of extracts delivering the Nrf2 activator sulforaphane reduced the degree of solar-simulated UV radiation-induced skin erythema, a quantifiable surrogate endpoint for cutaneous damage and skin cancer risk. Collectively, these data show that Nrf2 is not a driver for tumorigenesis even upon exposure to a very potent and complete carcinogen and strongly suggest that the frequent activation of Nrf2 in established human tumors is a marker of metabolic adaptation. ©2015 American Association for Cancer Research.

  14. Dynamic simulation of space heating systems with radiators controlled by TRVs in buildings

    Xu, Baoping; Fu, Lin; Di, Hongfa [Department of Building Science, School of Architecture, Tsinghua University, Beijing 100084 (China)

    2008-07-01

    The objective of this paper is to develop a model for simulating the thermal and hydraulic behavior of space heating systems with radiators controlled by thermostat valves (TRVs) in multi-family buildings. This is done by treating the building and the heating system as a complete entity. Sub-models for rooms, radiators, TRVs, and the hydraulic network are derived. Then the suggested sub-models are combined to form an integrated model by considering interactions between them. The proposed model takes into account the heat transfer between neighboring rooms, the transport delay in the radiator, the self-adjusting function of the TRV, and the consumer's regulation behavior, as well as the hydraulic interactions between consumers. To test the model, two space heating systems in Beijing and Tianjin were investigated, and the model was validated under three operation modes. There was good agreement between the measured and simulated values for room temperature, return water temperature, and flow rate. A modeling analysis case was given based on an existing building and heating system. It was found that when the set value of the TRVs were kept on 2-3, about 12.4% reduction of heat consumption could be gained, compared with the situation in which the TRVs were kept fully open. The water flow rate was an important index that truly reflected the heat load change. It was also noted that if the flow rate or supply water temperature changed much during the transport delay time in the radiator, ignoring the transport delay would introduce an obvious deviation of the simulation results. Additionally, when an apartment stopped using the heating system during a heating season, the heat consumption of its neighboring apartments would be increased about 6-14%. (author)

  15. Real-time 3D radiation risk assessment supporting simulation of work in nuclear environments

    Szoke, I; Louka, M N; Bryntesen, T R; Bratteli, J; Edvardsen, S T; RøEitrheim, K K; Bodor, K

    2014-01-01

    This paper describes the latest developments at the Institute for Energy Technology (IFE) in Norway, in the field of real-time 3D (three-dimensional) radiation risk assessment for the support of work simulation in nuclear environments. 3D computer simulation can greatly facilitate efficient work planning, briefing, and training of workers. It can also support communication within and between work teams, and with advisors, regulators, the media and public, at all the stages of a nuclear installation’s lifecycle. Furthermore, it is also a beneficial tool for reviewing current work practices in order to identify possible gaps in procedures, as well as to support the updating of international recommendations, dissemination of experience, and education of the current and future generation of workers. IFE has been involved in research and development into the application of 3D computer simulation and virtual reality (VR) technology to support work in radiological environments in the nuclear sector since the mid 1990s. During this process, two significant software tools have been developed, the VRdose system and the Halden Planner, and a number of publications have been produced to contribute to improving the safety culture in the nuclear industry. This paper describes the radiation risk assessment techniques applied in earlier versions of the VRdose system and the Halden Planner, for visualising radiation fields and calculating dose, and presents new developments towards implementing a flexible and up-to-date dosimetric package in these 3D software tools, based on new developments in the field of radiation protection. The latest versions of these 3D tools are capable of more accurate risk estimation, permit more flexibility via a range of user choices, and are applicable to a wider range of irradiation situations than their predecessors. (paper)

  16. Real-time 3D radiation risk assessment supporting simulation of work in nuclear environments.

    Szőke, I; Louka, M N; Bryntesen, T R; Bratteli, J; Edvardsen, S T; RøEitrheim, K K; Bodor, K

    2014-06-01

    This paper describes the latest developments at the Institute for Energy Technology (IFE) in Norway, in the field of real-time 3D (three-dimensional) radiation risk assessment for the support of work simulation in nuclear environments. 3D computer simulation can greatly facilitate efficient work planning, briefing, and training of workers. It can also support communication within and between work teams, and with advisors, regulators, the media and public, at all the stages of a nuclear installation's lifecycle. Furthermore, it is also a beneficial tool for reviewing current work practices in order to identify possible gaps in procedures, as well as to support the updating of international recommendations, dissemination of experience, and education of the current and future generation of workers.IFE has been involved in research and development into the application of 3D computer simulation and virtual reality (VR) technology to support work in radiological environments in the nuclear sector since the mid 1990s. During this process, two significant software tools have been developed, the VRdose system and the Halden Planner, and a number of publications have been produced to contribute to improving the safety culture in the nuclear industry.This paper describes the radiation risk assessment techniques applied in earlier versions of the VRdose system and the Halden Planner, for visualising radiation fields and calculating dose, and presents new developments towards implementing a flexible and up-to-date dosimetric package in these 3D software tools, based on new developments in the field of radiation protection. The latest versions of these 3D tools are capable of more accurate risk estimation, permit more flexibility via a range of user choices, and are applicable to a wider range of irradiation situations than their predecessors.

  17. Numerical simulation of heat transfer process in solar enhanced natural draft dry cooling tower with radiation model

    Wang, Qiuhuan; Zhu, Jialing; Lu, Xinli

    2017-01-01

    Graphical abstract: A 3-D numerical model integrated with a discrete ordinate (DO) solar radiation model (considering solar radiation effect in the room of solar collector) was developed to investigate the influence of solar radiation intensity and ambient pressure on the efficiency and thermal characteristics of the SENDDCT. Our study shows that introducing such a radiation model can more accurately simulate the heat transfer process in the SENDDCT. Calculation results indicate that previous simulations overestimated solar energy obtained by the solar collector and underestimated the heat loss. The cooling performance is improved when the solar radiation intensity or ambient pressure is high. Air temperature and velocity increase with the increase of solar radiation intensity. But ambient pressure has inverse effects on the changes of air temperature and velocity. Under a condition that the solar load increases but the ambient pressure decreases, the increased rate of heat transferred in the heat exchanger is not obvious. Thus the performance of the SENDDCT not only depends on the solar radiation intensity but also depends on the ambient pressure. - Highlights: • A radiation model has been introduced to accurately simulate heat transfer process. • Heat transfer rate would be overestimated if the radiation model was not introduced. • The heat transfer rate is approximately proportional to solar radiation intensity. • The higher the solar radiation or ambient pressure, the better SENDDCT performance. - Abstract: Solar enhanced natural draft dry cooling tower (SENDDCT) is more efficient than natural draft dry cooling tower by utilizing solar radiation in arid region. A three-dimensional numerical model considering solar radiation effect was developed to investigate the influence of solar radiation intensity and ambient pressure on the efficiency and thermal characteristics of SENDDCT. The numerical simulation outcomes reveal that a model with consideration of

  18. SKIRT: The design of a suite of input models for Monte Carlo radiative transfer simulations

    Baes, M.; Camps, P.

    2015-09-01

    The Monte Carlo method is the most popular technique to perform radiative transfer simulations in a general 3D geometry. The algorithms behind and acceleration techniques for Monte Carlo radiative transfer are discussed extensively in the literature, and many different Monte Carlo codes are publicly available. On the contrary, the design of a suite of components that can be used for the distribution of sources and sinks in radiative transfer codes has received very little attention. The availability of such models, with different degrees of complexity, has many benefits. For example, they can serve as toy models to test new physical ingredients, or as parameterised models for inverse radiative transfer fitting. For 3D Monte Carlo codes, this requires algorithms to efficiently generate random positions from 3D density distributions. We describe the design of a flexible suite of components for the Monte Carlo radiative transfer code SKIRT. The design is based on a combination of basic building blocks (which can be either analytical toy models or numerical models defined on grids or a set of particles) and the extensive use of decorators that combine and alter these building blocks to more complex structures. For a number of decorators, e.g. those that add spiral structure or clumpiness, we provide a detailed description of the algorithms that can be used to generate random positions. Advantages of this decorator-based design include code transparency, the avoidance of code duplication, and an increase in code maintainability. Moreover, since decorators can be chained without problems, very complex models can easily be constructed out of simple building blocks. Finally, based on a number of test simulations, we demonstrate that our design using customised random position generators is superior to a simpler design based on a generic black-box random position generator.

  19. Concatenating algorithms for parallel numerical simulations coupling radiation hydrodynamics with neutron transport

    Mo Zeyao

    2004-11-01

    Multiphysics parallel numerical simulations are usually essential to simplify researches on complex physical phenomena in which several physics are tightly coupled. It is very important on how to concatenate those coupled physics for fully scalable parallel simulation. Meanwhile, three objectives should be balanced, the first is efficient data transfer among simulations, the second and the third are efficient parallel executions and simultaneously developments of those simulation codes. Two concatenating algorithms for multiphysics parallel numerical simulations coupling radiation hydrodynamics with neutron transport on unstructured grid are presented. The first algorithm, Fully Loosely Concatenation (FLC), focuses on the independence of code development and the independence running with optimal performance of code. The second algorithm. Two Level Tightly Concatenation (TLTC), focuses on the optimal tradeoffs among above three objectives. Theoretical analyses for communicational complexity and parallel numerical experiments on hundreds of processors on two parallel machines have showed that these two algorithms are efficient and can be generalized to other multiphysics parallel numerical simulations. In especial, algorithm TLTC is linearly scalable and has achieved the optimal parallel performance. (authors)

  20. Towards an integrative computational model for simulating tumor growth and response to radiation therapy

    Marrero, Carlos Sosa; Aubert, Vivien; Ciferri, Nicolas; Hernández, Alfredo; de Crevoisier, Renaud; Acosta, Oscar

    2017-11-01

    Understanding the response to irradiation in cancer radiotherapy (RT) may help devising new strategies with improved tumor local control. Computational models may allow to unravel the underlying radiosensitive mechanisms intervening in the dose-response relationship. By using extensive simulations a wide range of parameters may be evaluated providing insights on tumor response thus generating useful data to plan modified treatments. We propose in this paper a computational model of tumor growth and radiation response which allows to simulate a whole RT protocol. Proliferation of tumor cells, cell life-cycle, oxygen diffusion, radiosensitivity, RT response and resorption of killed cells were implemented in a multiscale framework. The model was developed in C++, using the Multi-formalism Modeling and Simulation Library (M2SL). Radiosensitivity parameters extracted from literature enabled us to simulate in a regular grid (voxel-wise) a prostate cell tissue. Histopathological specimens with different aggressiveness levels extracted from patients after prostatectomy were used to initialize in silico simulations. Results on tumor growth exhibit a good agreement with data from in vitro studies. Moreover, standard fractionation of 2 Gy/fraction, with a total dose of 80 Gy as a real RT treatment was applied with varying radiosensitivity and oxygen diffusion parameters. As expected, the high influence of these parameters was observed by measuring the percentage of survival tumor cell after RT. This work paves the way to further models allowing to simulate increased doses in modified hypofractionated schemes and to develop new patient-specific combined therapies.

  1. Smoke, Clouds and Radiation Brazil NASA ER-2 Moderate Resolution Imaging Spectrometer (MODIS) Airborne Simulator (MAS) Data

    National Aeronautics and Space Administration — SCARB_ER2_MAS data are Smoke, Clouds and Radiation Brazil (SCARB) NASA ER2 Moderate Resolution Imaging Spectrometer (MODIS) Airborne Simulator (MAS)...

  2. The influence of photosynthetically-active radiation and simulated shadelight on the control of leaf growth of Betula and Acer

    Taylor, G.; Davies, W.J.

    1988-01-01

    The primary aim of the study was to quantify the effects of photosynthetically-active radiation (PAR) on extension of leaves of silver birch (Betula pendula Roth.) and sycamore (Acer pseudoplatanus L.). Plants grown at 250 μ mol m -2 s -1 were exposed to a range of fluence rates (0-680 μ mol m -2 s -1 ) whilst enclosed in Perspex chambers in which temperature, vapour pressure deficit and photoenvironment were all controlled. Measurements of leaf extension, water relations, and cell wall extensibility (WEX) were made at the end of a 3 h exposure period. For leaves of birch, reducing the fluence rate resulted in reduced leaf extension and a lowering of WEX. Exposure of sycamore seedlings for 3 h to different values of PAR had little effect on the growth of leaves and WEX remained constant. The characteristics of net photosynthesis also differed for the two species and photosynthesis and wall loosening may be linked. Since natural woodland shadelight, in addition to reduced PAR, also has a reduced R/FR ratio, a second group of seedlings were placed in a photoenvironment which simulated shadelight (low PAR, R/FR) for 28 d. This treatment reduced extension rate and final leaf size for both species. Measurements of extension, water relations and WEX made when seedlings were exposed to shadelight whilst held in the Perspex chambers revealed differences in the control of leaf growth for the two species. It is confirmed that leaves of birch are highly responsive to changes in PAR with cell wall loosening the most likely process controlling this response

  3. Radiation

    2013-01-01

    The chapter one presents the composition of matter and atomic theory; matter structure; transitions; origin of radiation; radioactivity; nuclear radiation; interactions in decay processes; radiation produced by the interaction of radiation with matter

  4. A stochastic simulation model for reliable PV system sizing providing for solar radiation fluctuations

    Kaplani, E.; Kaplanis, S.

    2012-01-01

    Highlights: ► Solar radiation data for European cities follow the Extreme Value or Weibull distribution. ► Simulation model for the sizing of SAPV systems based on energy balance and stochastic analysis. ► Simulation of PV Generator-Loads-Battery Storage System performance for all months. ► Minimum peak power and battery capacity required for reliable SAPV sizing for various European cities. ► Peak power and battery capacity reduced by more than 30% for operation 95% success rate. -- Abstract: The large fluctuations observed in the daily solar radiation profiles affect highly the reliability of the PV system sizing. Increasing the reliability of the PV system requires higher installed peak power (P m ) and larger battery storage capacity (C L ). This leads to increased costs, and makes PV technology less competitive. This research paper presents a new stochastic simulation model for stand-alone PV systems, developed to determine the minimum installed P m and C L for the PV system to be energy independent. The stochastic simulation model developed, makes use of knowledge acquired from an in-depth statistical analysis of the solar radiation data for the site, and simulates the energy delivered, the excess energy burnt, the load profiles and the state of charge of the battery system for the month the sizing is applied, and the PV system performance for the entire year. The simulation model provides the user with values for the autonomy factor d, simulating PV performance in order to determine the minimum P m and C L depending on the requirements of the application, i.e. operation with critical or non-critical loads. The model makes use of NASA’s Surface meteorology and Solar Energy database for the years 1990–2004 for various cities in Europe with a different climate. The results obtained with this new methodology indicate a substantial reduction in installed peak power and battery capacity, both for critical and non-critical operation, when compared to

  5. Dosimetric measurement of scattered radiation from dental implants in simulated head and neck radiotherapy.

    Wang, R; Pillai, K; Jones, P K

    1998-01-01

    The purpose of this study was to examine the dose enhancement at bone-implant interfaces from scattered radiation during simulated head and neck radiotherapy. Three cylindric implant systems with different compositions (pure titanium, titanium-aluminum-vanadium alloy, titanium coated with hydroxyapatite) and a high gold content transmandibular implant system (gold-copper-silver alloy) were studied. Extruded lithium fluoride single crystal chips were used as thermoluminescent material to measure radiation dose enhancement at 0, 1, and 2 mm from the bone-implant interface. The relative doses in buccal, lingual, mesial, and distal directions were also recorded and compared. The results indicated that the highest dose enhancement occurred at a distance of 0 mm from the bone-implant interface for all the implant systems studied. The transmandibular implants had higher scattered radiation than other groups at 0 mm and at 1 mm from the bone-implant interface. There was no significant difference of dose enhancement between buccal, lingual, mesial, and distal directions. Titanium implants coated with hydroxyapatite demonstrated the best results under the simulated irradiation.

  6. Toward Improving the Representation of Convection and Cloud-Radiation Interaction for Global Climate Simulations

    Wu, X.; Song, X.; Deng, L.; Park, S.; Liang, X.; Zhang, G. J.

    2006-05-01

    Despite the significant progress made in developing general circulation models (GCMs), major uncertainties related to the parameterization of convection, cloud and radiation processes still remain. The current GCM credibility of seasonal-interannual climate predictions or climate change projections is limited. In particular, the following long-standing biases, common to most GCMs, need to be reduced: 1) over-prediction of high-level cloud amounts although GCMs realistically simulating the global radiation budget; 2) general failure to reproduce the seasonal variation and migration of the ITCZ precipitation; 3) incomplete representation of the Madden-Julian Oscillation (MJO); and 4) false production of an excessive cold tone of sea surface temperature across the Pacific basin and a double ITCZ structure in precipitation when the atmosphere and ocean are fully coupled. The development of cloud-resolving models (CRMs) provides a unique opportunity to address issues aimed to reduce these biases. The statistical analysis of CRM simulations together with the theoretical consideration of subgrid-scale processes will enable us to develop physically-based parameterization of convection, clouds, radiation and their interactions.

  7. A computer simulation model to compute the radiation transfer of mountainous regions

    Li, Yuguang; Zhao, Feng; Song, Rui

    2011-11-01

    In mountainous regions, the radiometric signal recorded at the sensor depends on a number of factors such as sun angle, atmospheric conditions, surface cover type, and topography. In this paper, a computer simulation model of radiation transfer is designed and evaluated. This model implements the Monte Carlo ray-tracing techniques and is specifically dedicated to the study of light propagation in mountainous regions. The radiative processes between sun light and the objects within the mountainous region are realized by using forward Monte Carlo ray-tracing methods. The performance of the model is evaluated through detailed comparisons with the well-established 3D computer simulation model: RGM (Radiosity-Graphics combined Model) based on the same scenes and identical spectral parameters, which shows good agreements between these two models' results. By using the newly developed computer model, series of typical mountainous scenes are generated to analyze the physical mechanism of mountainous radiation transfer. The results show that the effects of the adjacent slopes are important for deep valleys and they particularly affect shadowed pixels, and the topographic effect needs to be considered in mountainous terrain before accurate inferences from remotely sensed data can be made.

  8. Monte Carlo simulation of muon radiation environment in China Jinping Underground Laboratory

    Su Jian; Zeng Zhi; Liu Yue; Yue Qian; Ma Hao; Cheng Jianping

    2012-01-01

    Muon radiation background of China Jinping Underground Laboratory (CJPL) was simulated by Monte Carlo method. According to the Gaisser formula and the MUSIC soft, the model of cosmic ray muons was established. Then the yield and the average energy of muon-induced photons and muon-induced neutrons were simulated by FLUKA. With the single-energy approximation, the contribution to the radiation background of shielding structure by secondary photons and neutrons was evaluated. The estimation results show that the average energy of residual muons is 369 GeV and the flux is 3.17 × 10 -6 m -2 · s -1 . The fluence rate of secondary photons is about 1.57 × 10 -4 m -2 · s -1 , and the fluence rate of secondary neutrons is about 8.37 × 10 -7 m -2 · s -1 . The muon radiation background of CJPL is lower than those of most other underground laboratories in the world. (authors)

  9. Simulating the spectrum and the polarization characteristics of coherent radiation from ultrarelativistic electrons in a diamond crystal

    Truten', V.I.

    2000-01-01

    On the basis of a computer simulation, it is shown that, in the spectrum of radiation from ultrarelativistic electrons in oriented crystals, new maxima can appear in the low-frequency region in addition to ordinary coherent maxima. This effect is due to the influence of high-index planes on the radiation in question. The aforementioned new maxima manifest themselves not only in the spectrum but also in the polarization characteristics of the radiation

  10. The Survival and Resistance of Halobacterium salinarum NRC-1, Halococcus hamelinensis, and Halococcus morrhuae to Simulated Outer Space Solar Radiation.

    Leuko, S; Domingos, C; Parpart, A; Reitz, G; Rettberg, P

    2015-11-01

    Solar radiation is among the most prominent stress factors organisms face during space travel and possibly on other planets. Our analysis of three different halophilic archaea, namely Halobacterium salinarum NRC-1, Halococcus morrhuae, and Halococcus hamelinensis, which were exposed to simulated solar radiation in either dried or liquid state, showed tremendous differences in tolerance and survivability. We found that Hcc. hamelinensis is not able to withstand high fluences of simulated solar radiation compared to the other tested organisms. These results can be correlated to significant differences in genomic integrity following exposure, as visualized by random amplified polymorphic DNA (RAPD)-PCR. In contrast to the other two tested strains, Hcc. hamelinensis accumulates compatible solutes such as trehalose for osmoprotection. The addition of 100 mM trehalose to the growth medium of Hcc. hamelinensis improved its survivability following exposure. Exposure of cells in liquid at different temperatures suggests that Hbt. salinarum NRC-1 is actively repairing cellular and DNA damage during exposure, whereas Hcc. morrhuae exhibits no difference in survival. For Hcc. morrhuae, the high resistance against simulated solar radiation may be explained with the formation of cell clusters. Our experiments showed that these clusters shield cells on the inside against simulated solar radiation, which results in better survival rates at higher fluences when compared to Hbt. salinarum NRC-1 and Hcc. hamelinensis. Overall, this study shows that some halophilic archaea are highly resistant to simulated solar radiation and that they are of high astrobiological significance. Halophiles-Solar radiation-Stress resistance-Survival.

  11. Radiative Hydrodynamic Simulations of In Situ Star Formation in the Galactic Center

    Frazer, Chris; Heitsch, Fabian

    2018-01-01

    Many stars observed in the Galactic Center (GC) orbit the supermassive black hole (SMBH), Sagittarius A*, in a region where the extreme gravitational field is expected to inhibit star formation. Yet, many of these stars are young which favors an in situ formation scenario. Previous numerical work on this topic has focused on two possible solutions. First, the tidal capture of a > 10^4 Msun infalling molecular cloud by an SMBH may result in the formation of a surrounding gas disk which then rapidly cools and forms stars. This process results in stellar populations that are consistent with the observed stellar disk in the GC. Second, dense gas clumps of approximately 100 Msun on highly eccentric orbits about an SMBH can experience sparks of star formation via orbital compressions occurring during pericenter passage. In my dissertation, I build upon these models using a series of grid-based radiative hydrodynamic simulations, including the effects of both ionizing ultraviolet light from existing stars as well as X-ray radiation emanating from the central black hole. Radiation is treated with an adaptive ray-tracing routine, including appropriate heating and cooling for both neutral and ionized gas. These models show that ultraviolet radiation is sufficiently strong to heat low mass gas clouds, thus suppressing star formation from clump compression. Gas disks that form from cloud capture become sufficiently dense to provide shielding from the radiation of existing central stars, thus allowing star formation to continue. Conversely, X-rays easily penetrate and heat the potentially star forming gas. For sufficiently high radiation fields, this provides a mechanism to disrupt star formation for both scenarios considered above.

  12. A Brief Introduction to Coloured Petri Nets

    Jensen, Kurt

    1997-01-01

    Coloured Petri Nets (CP-nets or CPN) is a graphical oriented language for design, specification, simulation and verification of systems. It is in particular well- suited for systems in which communication, synchronisation and resource sharing are important. Typical examples of application areas a...

  13. A Numerical Simulation for Prediction of Infrared Radiation Emitted from Plain Surfaces with Different Geometries

    Vakilabadi K.A.

    2017-08-01

    Full Text Available In this paper, infrared radiation exiting plain surfaces with different geometries is numerically simulated. Surfaces under consideration are assumed to have steady uniform heat generation inside. Moreover, the boundaries of the surfaces are considered to be at the surroundings temperature. Infrared radiation is calculated based on the temperature profile determined for the surface. The temperature profile of the surface is determined assuming the two dimensional heat conduction equations to govern the problem. The physical domain is transformed into the appropriate computational domain and the governing equation is mapped into the suitable forms in the new coordinate system of variables. After that the temperature profile of the surface is computed, the infrared radiation distribution of the surface is evaluated based on the equations given in the manuscript. The temperature profile as well as the IR images are given in the results section. It is concluded that the maximum value of infrared radiation of the surface occurs at the center. Moreover, it is concluded that among surfaces with equal areas, the one having the largest perimeter has the least value of IR at its center.

  14. Evaluation of a performance appraisal framework for radiation therapists in planning and simulation

    Becker, Jillian, E-mail: jillian.becker@health.qld.gov.au [Radiation Oncology Mater Centre, South Brisbane, Queensland (Australia); Bridge, Pete [School of Clinical Sciences, Queensland University of Technology, Brisbane, Queensland (Australia); Brown, Elizabeth; Lusk, Ryan; Ferrari-Anderson, Janet [Radiation Oncology, Princess Alexandra Hospital, Brisbane, Queensland (Australia); Radiation Oncology Mater Centre, South Brisbane, Queensland (Australia)

    2015-06-15

    Constantly evolving technology and techniques within radiation therapy require practitioners to maintain a continuous approach to professional development and training. Systems of performance appraisal and adoption of regular feedback mechanisms are vital to support this development yet frequently lack structure and rely on informal peer support. A Radiation Therapy Performance Appraisal Framework (RT-PAF) for radiation therapists in planning and simulation was developed to define expectations of practice and promote a supportive and objective culture of performance and skills appraisal. Evaluation of the framework was conducted via an anonymous online survey tool. Nine peer reviewers and fourteen recipients provided feedback on its effectiveness and the challenges and limitations of the approach. Findings from the evaluation were positive and suggested that both groups gained benefit from and expressed a strong interest in embedding the approach more routinely. Respondents identified common challenges related to the limited ability to implement suggested development strategies; this was strongly associated with time and rostering issues. This framework successfully defined expectations for practice and provided a fair and objective feedback process that focussed on skills development. It empowered staff to maintain their skills and reach their professional potential. Management support, particularly in regard to provision of protected time was highlighted as critical to the framework's ongoing success. The demonstrated benefits arising in terms of staff satisfaction and development highlight the importance of this commitment to the modern radiation therapy workforce.

  15. Radiation interaction with substance and simulation of the nuclear geophysical problems

    Pshenichnyj, G.A.

    1982-01-01

    Main processes of interaction of various types of nuclear radiation (NR) with substance, NR transport theory and physical- mathematical simulation of basic problems of nuclear geophysics (NG) are considered. General classification of NG methods according to the type of the detected radiation with a more detailed division according to the physical essence of the interaction process employed is given. Direct NG problems are related to the study of space- energy radiation distribution in substance under certain cross sections of elementary interaction processes, substance properties and specified geometric conditions. The theoretical solution of the direct problems is based on using mathematical models of radiation transport in specified media. The NG inverse problems consist in determining element composition and other medium properties by data of integral or spectral characteristics of NR fields measurements. The NR in the course of its transport in substance can experience dozens of elementary interaction processes, the predominance of this or that process depending on NR energy, medium properties and geometric measurement conditions. This explains a wide NG method diversity. The Monte Carlo method application in the NR transport theory and various methods of decreasing calculations labour input are considered [ru

  16. Evaluation of a performance appraisal framework for radiation therapists in planning and simulation

    Becker, Jillian; Bridge, Pete; Brown, Elizabeth; Lusk, Ryan; Ferrari-Anderson, Janet

    2015-01-01

    Constantly evolving technology and techniques within radiation therapy require practitioners to maintain a continuous approach to professional development and training. Systems of performance appraisal and adoption of regular feedback mechanisms are vital to support this development yet frequently lack structure and rely on informal peer support. A Radiation Therapy Performance Appraisal Framework (RT-PAF) for radiation therapists in planning and simulation was developed to define expectations of practice and promote a supportive and objective culture of performance and skills appraisal. Evaluation of the framework was conducted via an anonymous online survey tool. Nine peer reviewers and fourteen recipients provided feedback on its effectiveness and the challenges and limitations of the approach. Findings from the evaluation were positive and suggested that both groups gained benefit from and expressed a strong interest in embedding the approach more routinely. Respondents identified common challenges related to the limited ability to implement suggested development strategies; this was strongly associated with time and rostering issues. This framework successfully defined expectations for practice and provided a fair and objective feedback process that focussed on skills development. It empowered staff to maintain their skills and reach their professional potential. Management support, particularly in regard to provision of protected time was highlighted as critical to the framework's ongoing success. The demonstrated benefits arising in terms of staff satisfaction and development highlight the importance of this commitment to the modern radiation therapy workforce

  17. Using probabilistic finite automata to simulate hourly series of global radiation

    Mora-Lopez, L. [Universidad de Malaga (Spain). Dpto. Lenguajes y Computacion; Sidrach-de-Cardona, M. [Universidad de Malaga (Spain). Dpto. Fisica Aplicada II

    2003-03-01

    A model to generate synthetic series of hourly exposure of global radiation is proposed. This model has been constructed using a machine learning approach. It is based on the use of a subclass of probabilistic finite automata which can be used for variable-order Markov processes. This model allows us to represent the different relationships and the representative information observed in the hourly series of global radiation; the variable-order Markov process can be used as a natural way to represent different types of days, and to take into account the ''variable memory'' of cloudiness. A method to generate new series of hourly global radiation, which incorporates the randomness observed in recorded series, is also proposed. As input data this method only uses the mean monthly value of the daily solar global radiation. We examine if the recorded and simulated series are similar. It can be concluded that both series have the same statistical properties. (author)

  18. Study by dislocation dynamics simulations of radiation effects on the plasticity of ferrite at high temperature

    Shi, Xiangjun

    2014-01-01

    This study is a contribution to the multi-scale modeling of hardening and embrittlement of the vessel steel in Pressurized Water Reactors (PWR) under irradiation conditions. Dislocation Dynamics simulations (DD) were conducted to describe the plasticity of irradiated iron at grain scale. Quantitative information about the pinning strength of radiation-induced loops was extracted and can be transferred at crystal plasticity scale. Elementary interactions between an edge dislocation and different types of loops were first analyzed. A new model of DD was identified and validated, both qualitatively in terms of interaction mechanisms and quantitatively in terms of critical stress, using Molecular Dynamics results available in the literature. The influence of the size of the loops and of the strain rate was particularly studied. Elementary simulations involving a screw dislocation and the same radiation-induced defects were conducted and carefully compared to available MD results, extending the range of validity of our model. Finally, a set of massive simulations involving an edge dislocation and a large number of loops was performed and allowed a first estimation of the obstacle strength for this type of defects (α≅0.26). This value is in a good agreement with previous experimental and numerical studies, and gives us confidence in future work based on this new DD model. (author) [fr

  19. Rupture Dynamics and Seismic Radiation on Rough Faults for Simulation-Based PSHA

    Mai, P. M.; Galis, M.; Thingbaijam, K. K. S.; Vyas, J. C.; Dunham, E. M.

    2017-12-01

    Simulation-based ground-motion predictions may augment PSHA studies in data-poor regions or provide additional shaking estimations, incl. seismic waveforms, for critical facilities. Validation and calibration of such simulation approaches, based on observations and GMPE's, is important for engineering applications, while seismologists push to include the precise physics of the earthquake rupture process and seismic wave propagation in 3D heterogeneous Earth. Geological faults comprise both large-scale segmentation and small-scale roughness that determine the dynamics of the earthquake rupture process and its radiated seismic wavefield. We investigate how different parameterizations of fractal fault roughness affect the rupture evolution and resulting near-fault ground motions. Rupture incoherence induced by fault roughness generates realistic ω-2 decay for high-frequency displacement amplitude spectra. Waveform characteristics and GMPE-based comparisons corroborate that these rough-fault rupture simulations generate realistic synthetic seismogram for subsequent engineering application. Since dynamic rupture simulations are computationally expensive, we develop kinematic approximations that emulate the observed dynamics. Simplifying the rough-fault geometry, we find that perturbations in local moment tensor orientation are important, while perturbations in local source location are not. Thus, a planar fault can be assumed if the local strike, dip, and rake are maintained. The dynamic rake angle variations are anti-correlated with local dip angles. Based on a dynamically consistent Yoffe source-time function, we show that the seismic wavefield of the approximated kinematic rupture well reproduces the seismic radiation of the full dynamic source process. Our findings provide an innovative pseudo-dynamic source characterization that captures fault roughness effects on rupture dynamics. Including the correlations between kinematic source parameters, we present a new

  20. FULL ELECTROMAGNETIC SIMULATION OF COHERENT SYNCHROTRON RADIATION VIA THE LORENTZ-BOOSTED FRAME APPROACH

    Fawley, William M.; Vay, Jean-Luc

    2010-01-01

    Numerical simulation of some systems containing charged particles with highly relativistic directed motion can by speeded up by orders of magnitude by choice of the proper Lorentz-boosted frame. Orders of magnitude speedup has been demonstrated for simulations from first principles of laser-plasma accelerator, free electron laser, and particle beams interacting with electron clouds. Here we address the application of the Lorentz-boosted frame approach to coherent synchrotron radiation (CSR), which can be strongly present in bunch compressor chicanes. CSR is particularly relevant to the next generation of x-ray light sources and is simultaneously difficult to simulate in the lab frame because of the large ratio of scale lengths. It can increase both the incoherent and coherent longitudinal energy spread, effects that often lead to an increase in transverse emittance. We have adapted the WARP code to simulate CSR emission along a simple dipole bend. We present some scaling arguments for the possible computational speed up factor in the boosted frame and initial 3D simulation results.

  1. MONTE CARLO RADIATION TRANSFER SIMULATIONS OF PHOTOSPHERIC EMISSION IN LONG-DURATION GAMMA-RAY BURSTS

    Lazzati, Davide [Department of Physics, Oregon State University, 301 Weniger Hall, Corvallis, OR 97331 (United States)

    2016-10-01

    We present MCRaT, a Monte Carlo Radiation Transfer code for self-consistently computing the light curves and spectra of the photospheric emission from relativistic, unmagnetized jets. We apply MCRaT to a relativistic hydrodynamic simulation of a long-duration gamma-ray burst jet, and present the resulting light curves and time-dependent spectra for observers at various angles from the jet axis. We compare our results to observational results and find that photospheric emission is a viable model to explain the prompt phase of long-duration gamma-ray bursts at the peak frequency and above, but faces challenges when reproducing the flat spectrum below the peak frequency. We finally discuss possible limitations of these results both in terms of the hydrodynamics and the radiation transfer and how these limitations could affect the conclusions that we present.

  2. Simulation of radiation effects on three-dimensional computer optical memories

    Moscovitch, M.; Emfietzoglou, D.

    1997-01-01

    A model was developed to simulate the effects of heavy charged-particle (HCP) radiation on the information stored in three-dimensional computer optical memories. The model is based on (i) the HCP track radial dose distribution, (ii) the spatial and temporal distribution of temperature in the track, (iii) the matrix-specific radiation-induced changes that will affect the response, and (iv) the kinetics of transition of photochromic molecules from the colored to the colorless isomeric form (bit flip). It is shown that information stored in a volume of several nanometers radius around the particle close-quote s track axis may be lost. The magnitude of the effect is dependent on the particle close-quote s track structure. copyright 1997 American Institute of Physics

  3. Diagnosing Model Errors in Simulations of Solar Radiation on Inclined Surfaces: Preprint

    Xie, Yu; Sengupta, Manajit

    2016-06-01

    Transposition models have been widely used in the solar energy industry to simulate solar radiation on inclined PV panels. Following numerous studies comparing the performance of transposition models, this paper aims to understand the quantitative uncertainty in the state-of-the-art transposition models and the sources leading to the uncertainty. Our results suggest that an isotropic transposition model developed by Badescu substantially underestimates diffuse plane-of-array (POA) irradiances when diffuse radiation is perfectly isotropic. In the empirical transposition models, the selection of empirical coefficients and land surface albedo can both result in uncertainty in the output. This study can be used as a guide for future development of physics-based transposition models.

  4. Galactic Winds Driven by Supernovae and Radiation Pressure: Theory and Simulations

    Zhang, Dong; Davis, Shane

    2018-01-01

    Galactic winds are ubiquitous in most rapidly star-forming galaxies. They are crucial to the process of galaxy formation and evolution, regulating star formation, shaping the stellar mass function and the mass-metallicity relation, and enriching the intergalactic medium with metals. Although important, the physics of galactic winds is still unclear. Winds may be driven by many mechanisms including overlapping supernovae explosions, radiation pressure of starlight on dust grains, and cosmic rays. However, the growing observations of multiphase structure in galactic winds in a large number of galaxies have not been well explained by any models. In this talk I will focus on the models of supernova- and radiation-pressure-driven winds. Using the state-of-the-art numerical simulations, I will assess the relative merits of these driving mechanisms for accelerating cold and warm clouds to observed velocities, and momentum flux boost during wind propagation.

  5. Experimental simulation of the bubble membrane radiator using a rotating flat plate

    Al-Baroudi, H.; Klein, A.C.; Pauley, K.A.

    1991-01-01

    The Bubble Membrane Radiator (BMR), to be used in space reactor systems, uses artificial gravity imposed on the working fluid by means of the centrifugal force to pump the fluid from the radiator. Experimental and analytical studies have been initiated to understand the nature of fluid and heat transport under the conditions of rotation. An experiment is described which measures the condensation of vapor on a rotating flat plate which is oriented normal to the earth's gravity vector to simulate the BMR physics. The relationship between vapor flow rates and rotation speed of the flat plate and a number of physical parameters including amount of condensate, overall heat transfer coefficient, and condensate film thickness are studied experimentally

  6. Simulation of radiation effects on three-dimensional computer optical memories

    Moscovitch, M.; Emfietzoglou, D.

    1997-01-01

    A model was developed to simulate the effects of heavy charged-particle (HCP) radiation on the information stored in three-dimensional computer optical memories. The model is based on (i) the HCP track radial dose distribution, (ii) the spatial and temporal distribution of temperature in the track, (iii) the matrix-specific radiation-induced changes that will affect the response, and (iv) the kinetics of transition of photochromic molecules from the colored to the colorless isomeric form (bit flip). It is shown that information stored in a volume of several nanometers radius around the particle's track axis may be lost. The magnitude of the effect is dependent on the particle's track structure.

  7. Semi-automatic watershed medical image segmentation methods for customized cancer radiation treatment planning simulation

    Kum Oyeon; Kim Hye Kyung; Max, N.

    2007-01-01

    A cancer radiation treatment planning simulation requires image segmentation to define the gross tumor volume, clinical target volume, and planning target volume. Manual segmentation, which is usual in clinical settings, depends on the operator's experience and may, in addition, change for every trial by the same operator. To overcome this difficulty, we developed semi-automatic watershed medical image segmentation tools using both the top-down watershed algorithm in the insight segmentation and registration toolkit (ITK) and Vincent-Soille's bottom-up watershed algorithm with region merging. We applied our algorithms to segment two- and three-dimensional head phantom CT data and to find pixel (or voxel) numbers for each segmented area, which are needed for radiation treatment optimization. A semi-automatic method is useful to avoid errors incurred by both human and machine sources, and provide clear and visible information for pedagogical purpose. (orig.)

  8. Photodegradation of the herbicide azimsulfuron using nanocrystalline titania films as photocatalyst and low intensity Black Light radiation or simulated solar radiation as excitation source

    Pelentridou, Katerina; Stathatos, Elias; Karasali, Helen; Lianos, Panagiotis

    2009-01-01

    Aqueous solutions of the herbicide azimsulfuron have been treated by a photocatalytic process employing titania nanocrystalline films as photocatalyst. Results showed that solutions of this herbicide at maximum possible concentration can be photodegraded in a time of a few hours by using low intensity UVA radiation comparable with that of the UVA of solar noon. Similar results have also been obtained with simulated solar radiation. Thus heterogeneous photocatalysis can be employed for the treatment of waters polluted by this herbicide

  9. Assessment of 1D and 3D model simulated radiation flux based on surface measurements and estimation of aerosol forcing and their climatological aspects

    Subba, T.; Gogoi, M. M.; Pathak, B.; Ajay, P.; Bhuyan, P. K.; Solmon, F.

    2018-05-01

    Ground reaching solar radiation flux was simulated using a 1-dimensional radiative transfer (SBDART) and a 3-dimensional regional climate (RegCM 4.4) model and their seasonality against simultaneous surface measurements carried out using a CNR4 net Radiometer over a sub-Himalayan foothill site of south-east Asia was assessed for the period from March 2013-January 2015. The model simulated incoming fluxes showed a very good correlation with the measured values with correlation coefficient R2 0.97. The mean bias errors between these two varied from -40 W m-2 to +7 W m-2 with an overestimation of 2-3% by SBDART and an underestimation of 2-9% by RegCM. Collocated measurements of the optical parameters of aerosols indicated a reduction in atmospheric transmission path by 20% due to aerosol load in the atmosphere when compared with the aerosol free atmospheric condition. Estimation of aerosol radiative forcing efficiency (ARFE) indicated that the presence of black carbon (BC, 10-15%) led to a surface dimming by -26.14 W m-2 τ-1 and a potential atmospheric forcing of +43.04 W m-2 τ-1. BC alone is responsible for >70% influence with a major role in building up of forcing efficiency of +55.69 W m-2 τ-1 (composite) in the atmosphere. On the other hand, the scattering due to aerosols enhance the outgoing radiation at the top of the atmosphere (ARFETOA -12.60 W m-2 ω-1), the absence of which would have resulted in ARFETOA of +16.91 W m-2 τ-1 (due to BC alone). As a result, 3/4 of the radiation absorption in the atmosphere is ascribed to the presence of BC. This translated to an atmospheric heating rate of 1.0 K day-1, with 0.3 K day-1 heating over the elevated regions (2-4 km) of the atmosphere, especially during pre-monsoon season. Comparison of the satellite (MODIS) derived and ground based estimates of surface albedo showed seasonal difference in their magnitudes (R2 0.98 during retreating monsoon and winter; 0.65 during pre-monsoon and monsoon), indicating that the

  10. Bacterial growth in humic waters exposed to UV-radiation and simulated sunlight

    Corin, N.; Backlund, P.; Wiklund, T.

    1998-01-01

    Sterile filtered (0.45 mu m) humic lake water was exposed to simulated sunlight (300-800 nm) or W-radiation (254 run)for various periods of times and the dissolved organic carbon content, absorbance at 254 and 460 nm and PH were recorded. The irradiated water was inoculated with a natural bacterial...... assemblage and the number of viable bacteria war estimated 3 and 5 days after the inoculation using the plate count technique. The number of viable bacteria increased with the irradiation time indicating that the chemical changes of the humus macromolecules observed during irradiation resulted...

  11. Computer simulation of threshold radiation damage in rutile, TiO2

    Richardson, D.D.

    1983-01-01

    Computer simulation methods have been used to study threshold radiation damage structures in rutile. It was found Ti ions have threshold energies much larger than O ions. Basal plane displacements for oxygen were shown to be complex, and focuson behaviour was only found at energies several times the threshold energy. Oxygen ions do not have simple interstitials or vacancies, but rather a three-ion crowdion and divacancy-interstitial combination were found, respectively. Threshold energies were found to be highly dependent on crystallographic direction, being as low as 10 eV in one instance, but often much higher. Oxygen ions were seen to defocus along the c-axis. (author)

  12. Near-field characteristics of radiating-wave simulator antenna based on TEM horn

    Tian Chunming; Ge Debiao

    2004-01-01

    This paper presents a novel antenna of NEMP (nuclear electromagnetic pulse) radiating-wave simulator, which is analyzed and optimized using the finite-difference time domain (FDTD) method. The intense voltage pulse is fed as the source to this antenna by the coaxial line. The parallel plate transmission line and the size of the transverse electromagnetic horn are optimized. The near field of antenna is analyzed, and the effects of the size on the near field are also given. The antenna designed in this paper can well satisfy the requirement for studying the EMP effects

  13. Complex of electrostatic accelerators for simulation and diagnostics of radiation damage

    Antuf'ev, Yu.P.; Belyaev, V.Kh.; Vergunov, A.D.

    1983-01-01

    The installation for simulation and diagnostics of radiation damage of materials is described. The installation consists of two electrostatic accelerators of vertical type for 5 MV and horizontal type for 800 kV. The accelerating complex ensures accelerated ion beam production in the independent operation regime as well as in the two beams target simultaneous irradiation regime, energy range of accelerated single-charged ions is 80 keV ... 5 MeV, homogeneity is better than +-0.05%. Oilless vacuum pumping out system is realized at the accelerating complex

  14. Detecting Structural Features in Metallic Glass via Synchrotron Radiation Experiments Combined with Simulations

    Gu-Qing Guo

    2015-11-01

    Full Text Available Revealing the essential structural features of metallic glasses (MGs will enhance the understanding of glass-forming mechanisms. In this work, a feasible scheme is provided where we performed the state-of-the-art synchrotron-radiation based experiments combined with simulations to investigate the microstructures of ZrCu amorphous compositions. It is revealed that in order to stabilize the amorphous state and optimize the topological and chemical distribution, besides the icosahedral or icosahedral-like clusters, other types of clusters also participate in the formation of the microstructure in MGs. This cluster-level co-existing feature may be popular in this class of glassy materials.

  15. The effect of laser radiation on eyesight and determination of safety distance when using laser simulators

    Rakochevicj, S.; Dugandzhija, S.

    1989-01-01

    The influence of laser emission from the GaAs laser in a spectrum close infrared range on human eye and skin has been discussed. The application of gallium arsenide laser injections includes laser simulators. Analytic expression is defined. It is used to calculate the safety distance for the given parameters. There is a diagram of the programme procedure for calculation and graphical analysis of safety distance. Typical dependences of safety distance on the energy and divergency of laser radiation are discussed. (author). 5 refs.; 14 figs

  16. Fission fragment simulation of fusion neutron radiation effects on bulk mechanical properties

    Van Konynenburg, R.A.; Mitchell, J.B.; Guinan, M.W.; Stuart, R.N.; Borg, R.J.

    1976-01-01

    This research demonstrates the feasibility of using homogeneously-generated fission fragments to simulate high-fluence fusion neutron damage in niobium tensile specimens. This technique makes it possible to measure radiation effects on bulk mechanical properties at high damage states, using conveniently short irradiation times. The primary knock-on spectrum for a fusion reactor is very similar to that produced by fission fragments, and nearly the same ratio of gas atoms to displaced atoms is produced in niobium. The damage from fission fragments is compared to that from fusion neutrons and fission reactor neutrons in terms of experimentally measured yield strength increase, transmission electron microscopy (TEM) observations, and calculated damage energies

  17. Transport simulations of a density limit in radiation-dominated tokamak discharges: II

    Stotler, D.P.

    1991-05-01

    The procedures developed previously to simulate the radiatively induced tokamak density limit are used to examine in more detail the scaling of the density limit. It is found that the maximum allowable density increases with auxiliary power and decreases with impurity concentration. However, it is demonstrated that there is little dependence of the density limit on plasma elongation. These trends are consistent with experimental results. Our previous work used coronal equilibrium impurities; the primary result of that paper was that the maximum density increases with current when peaked profiles are assumed. Here, this behavior is shown to occur with a coronal nonequilibrium impurity as well. 26 refs., 4 figs

  18. Incorporation of Three-dimensional Radiative Transfer into a Very High Resolution Simulation of Horizontally Inhomogeneous Clouds

    Ishida, H.; Ota, Y.; Sekiguchi, M.; Sato, Y.

    2016-12-01

    A three-dimensional (3D) radiative transfer calculation scheme is developed to estimate horizontal transport of radiation energy in a very high resolution (with the order of 10 m in spatial grid) simulation of cloud evolution, especially for horizontally inhomogeneous clouds such as shallow cumulus and stratocumulus. Horizontal radiative transfer due to inhomogeneous clouds seems to cause local heating/cooling in an atmosphere with a fine spatial scale. It is, however, usually difficult to estimate the 3D effects, because the 3D radiative transfer often needs a large resource for computation compared to a plane-parallel approximation. This study attempts to incorporate a solution scheme that explicitly solves the 3D radiative transfer equation into a numerical simulation, because this scheme has an advantage in calculation for a sequence of time evolution (i.e., the scene at a time is little different from that at the previous time step). This scheme is also appropriate to calculation of radiation with strong absorption, such as the infrared regions. For efficient computation, this scheme utilizes several techniques, e.g., the multigrid method for iteration solution, and a correlated-k distribution method refined for efficient approximation of the wavelength integration. For a case study, the scheme is applied to an infrared broadband radiation calculation in a broken cloud field generated with a large eddy simulation model. The horizontal transport of infrared radiation, which cannot be estimated by the plane-parallel approximation, and its variation in time can be retrieved. The calculation result elucidates that the horizontal divergences and convergences of infrared radiation flux are not negligible, especially at the boundaries of clouds and within optically thin clouds, and the radiative cooling at lateral boundaries of clouds may reduce infrared radiative heating in clouds. In a future work, the 3D effects on radiative heating/cooling will be able to be

  19. Simulations of hybrid system varying solar radiation and microturbine response time

    Yolanda Fernández Ribaya

    2015-07-01

    Full Text Available Hybrid power systems, such as combinations of renewable power sources with intermittent power production and non-renewable power sources, theoretically increase the reliability and thus integration of renewable sources in the electrical system. However, a recent increase in the number of hybrid installations has sparked interest in the effects of their connection to the grid, especially in remote areas. This paper analyses a photovoltaic-gas microturbine hybrid system dimensioned to be installed in La Paz (Mexico.The research presented in this paper studies and quantifies the effects on the total electric power produced, varying both the solar radiation and the gas microturbine response time. The gas microturbine and the photovoltaic panels are modelled using Matlab/Simulink software, obtaining a platform where different tests to simulate real conditions have been executed. They consist of diverse ramps of irradiance that replicate solar radiation variations, and different microturbine response times reproduced by the time constants of a first order transfer function that models the microturbine dynamic response. The results obtained show that when radiation varies quickly it does not produce significant differences in the power guarantee or the microturbine gas consumption, to any microturbine response time. However, these two parameters are highly variable with smooth radiance variations. The maximum total power variation decreases greatly as the radiation variation gets lower. In addition, by decreasing the microturbine response time, it is possible to appreciably increase the power guarantee although the maximum power variation and gas consumption increase. Only in cases of low radiation variation is there no appreciable difference in the maximum power variation obtained by the different turbine response times.

  20. Simulations of hybrid system varying solar radiation and microturbine response time

    Fernández Ribaya, Yolanda, E-mail: fernandezryolanda@uniovi.es; Álvarez, Eduardo; Paredes Sánchez, José Pablo; Xiberta Bernat, Jorge [Department of Energy E.I.M.E.M., University of Oviedo. 13 Independencia Street 2" n" d floor, 36004, Oviedo (Spain)

    2015-07-15

    Hybrid power systems, such as combinations of renewable power sources with intermittent power production and non-renewable power sources, theoretically increase the reliability and thus integration of renewable sources in the electrical system. However, a recent increase in the number of hybrid installations has sparked interest in the effects of their connection to the grid, especially in remote areas. This paper analyses a photovoltaic-gas microturbine hybrid system dimensioned to be installed in La Paz (Mexico).The research presented in this paper studies and quantifies the effects on the total electric power produced, varying both the solar radiation and the gas microturbine response time. The gas microturbine and the photovoltaic panels are modelled using Matlab/Simulink software, obtaining a platform where different tests to simulate real conditions have been executed. They consist of diverse ramps of irradiance that replicate solar radiation variations, and different microturbine response times reproduced by the time constants of a first order transfer function that models the microturbine dynamic response. The results obtained show that when radiation varies quickly it does not produce significant differences in the power guarantee or the microturbine gas consumption, to any microturbine response time. However, these two parameters are highly variable with smooth radiance variations. The maximum total power variation decreases greatly as the radiation variation gets lower. In addition, by decreasing the microturbine response time, it is possible to appreciably increase the power guarantee although the maximum power variation and gas consumption increase. Only in cases of low radiation variation is there no appreciable difference in the maximum power variation obtained by the different turbine response times.

  1. Molecular dynamics simulations of radiation damage in D019 Ti3Al intermetallic compound

    Voskoboinikov, Roman E.

    2013-01-01

    Molecular dynamics (MD) has been applied to simulate the radiation damage created in displacement cascades in D0 19 Ti 3 Al structural intermetallics. Collision cascades formed by the recoil of either Al or Ti primary knock-on atoms (PKA) with energy E PKA = 5, 10, 15 or 20 keV were considered in Ti 3 Al single crystals at T = 100, 300, 600 and 900 K. At least 24 different cascades for each (E PKA , T, PKA type) set were simulated. A comprehensive treatment of the modelling results has been carried out. We have evaluated the number of Frenkel pairs, fraction of Al and Ti vacancies, self-interstitial atoms and anti-sites as a function of (E PKA ,T, PKA type). Preferred formation of both Al vacancies and self-interstitial atoms in D0 19 Ti 3 Al exposed to irradiation has been detected

  2. Radiation defects in Te-implanted germanium. Electron microscopy and computer simulation studies

    Kalitzova, M.G.; Karpuzov, D.S.; Pashov, N.K.

    1985-01-01

    Direct observation of radiation damage induced by heavy ion implantation in crystalline germanium by means of high-resolution electron microscopy is reported. The dark-field lattice imaging mode is used, under conditions suitable for object-like imaging. Conventional TEM is used for estimating the efficiency of creating visibly damaged regions. Heavy ion damage clusters with three types of inner structure are observed: with near-perfect crystalline cores, and with metastable and stable amorphous cores. The MARLOWE computer code is used to simulate the atomic collision cascades and to obtain the lateral spread distributions of point defects created. A comparison of high-resolution electron microscopy (HREM) with computer simulation results shows encouraging agreement for the average cluster dimensions and for the lateral spread of vacancies and interstitials. (author)

  3. Radiation-MHD simulations for the development of a spark discharge channel.

    Niederhaus, John Henry; Jorgenson, Roy E.; Warne, Larry K.; Chen, Kenneth C.

    2017-04-01

    The growth of a cylindrical s park discharge channel in water and Lexan is studied using a series of one - dimensional simulations with the finite - element radiation - magnetohydrodynamics code ALEGRA. Computed solutions are analyzed in order to characterize the rate of growth and dynamics of the spark c hannels during the rising - current phase of the drive pulse. The current ramp rate is varied between 0.2 and 3.0 kA/ns, and values of the mechanical coupling coefficient K p are extracted for each case. The simulations predict spark channel expansion veloc ities primarily in the range of 2000 to 3500 m/s, channel pressures primarily in the range 10 - 40 GPa, and K p values primarily between 1.1 and 1.4. When Lexan is preheated, slightly larger expansion velocities and smaller K p values are predicted , but the o verall behavior is unchanged.

  4. PSOD: an interactive Fortran program to simulate the radiation dose response of membrane populations

    Perry, K.A.; Szekely, J.G.

    1982-04-01

    Program PSOD was written to simulate the distribution in responses of membrane populations subjected to random radiation doses and dose rates. It computes the response (damage) according to one of three formulas selected by the user, and outputs statistical results to the terminal. It will plot simulated dose- and response-frequency distributions in two or three dimensions. Doses and dose rates are selected from the log normal distribution; other distributions can be incorporated as the need arises. A true log normal curve with defined mean and standard deviation can also be generated. The purpose of this documentation is to provide a complete operating manual for the program. A user guide is available on-line after initiating a session of PSOD. Detailed examinations of the statistical validity of various steps have been included to aid future modifications and updating

  5. First characterization and comparison of TEB model simulations with in situ measurements regarding radiation balance in a single urban canyon at the BOKU site (Vienna)

    Oswald, Sandro; Trimmel, Heidelinde; Revesz, Michael; Nadeem, Imran; Masson, Valéry; Weihs, Philipp

    2017-04-01

    According to the World Health Organization more than half of the world population lives in a city since 2010. Predictions foresee that by 2030 six out of ten people will live in an urban area. As a result, many cities are expanding in size. Almost 10% of all urban dwellers live in megacities (defined according to UN HABITAT as a city with a population of more than 10 million). There are several effects in cities which strongly influence human health. Visible influences like the severe emissions of air pollutants by industry and traffic (e.g. Mayer H., 1999, Grimmond et al., 2010) are obvious to people but thermal stress in urban areas is only recently recognized for its strong devastating effect on human health. As a consequence, the urban environment virtually influences all weather parameters that have an impact on human comfort and thermal stress. Within this study, we investigate effects of city growth and the development of outlying districts on the local climate of Vienna. We focus particularly on the influence of urban heat island and consequent the risk for heat related illnesses or thermal stress for people. To quantify radiation balance and other important meteorological factors, we performed an extensive field campaign with three types of net radiometer in three different heights at BOKU site in August 2016. The first results indicated a strong correlation (ρ=0.96) between the Town Energy Balance (TEB) model and the measurements of the top net radiometer regarding radiation balance at roof level, meanwhile the TEB results are slightly underestimated. Further check if the measurements are reasonable, a comparison of the input values (global and direct solar radiation) for the TEB simulation with Secondary Standard measurements of ARAD site Wien Hohe Warte shows a deviation under 2% concerning interquartile range on clear sky days. The next steps will enclose TEB simulations, coupled with the mesoscale Weather Research and Forecasting (WRF) model, for

  6. Radiação, fotossíntese, rendimento e qualidade de frutos em macieiras 'Royal Gala' cobertas com telas antigranizo Radiation, photosynthesis, yield, and fruit quality of 'Royal Gala' apples under hail protection nets

    Cassandro Vidal Talamini do Amarante

    2007-07-01

    Full Text Available O objetivo deste trabalho foi avaliar a intensidade e a qualidade da radiação solar disponibilizada às plantas e os seus impactos sobre a fotossíntese, rendimento e qualidade dos frutos, em macieiras 'Royal Gala', cobertas ou não com telas antigranizo nas cores branca e preta. A tela preta provocou redução maior na densidade de fluxo de fótons fotossinteticamente ativos acima do dossel das plantas (24,8%, em comparação à tela branca (21,2%. O interior do dossel das plantas sob tela preta recebeu menores valores de radiação ultravioleta, azul, verde, vermelho e vermelho distante, bem como da relação vermelho:vermelho distante, em relação às plantas descobertas. Estas alterações na quantidade e qualidade da luz sob tela preta aumentaram o teor de clorofila total e a área específica nas folhas, e reduziram a taxa fotossintética potencial, o peso de frutos por cm² de seção transversal de tronco e a coloração vermelha dos frutos. As telas antigranizo branca e preta reduziram a incidência de queimadura de sol, porém não tiveram efeito sobre a severidade de "russeting" e sobre o número de sementes por fruto.The objective of this work was to assess the amount and quality of the light supplied to plants, and the resulting impacts on photosynthesis, yield, and fruit quality of 'Royal Gala' apple trees uncovered or covered with white and black hail protection nets. The black net caused a higher reduction (24.8% of photosynthetic photon flux density, accumulated over the plant canopy during the day, than the white net (21.2%. The canopy internal portion of plants covered by black net received lower levels of ultraviolet, blue, green, red, and far red radiation, and light with a lower red:far red ratio, in comparison to uncovered plants; these ligth changes increased chlorophyll content and specific area of the leaves, and reduced the potential photosynthesis, the weight of fruits per cm² of trunk cross section area, and the

  7. SU-F-J-178: A Computer Simulation Model Observer for Task-Based Image Quality Assessment in Radiation Therapy

    Dolly, S; Mutic, S; Anastasio, M; Li, H; Yu, L

    2016-01-01

    Purpose: Traditionally, image quality in radiation therapy is assessed subjectively or by utilizing physically-based metrics. Some model observers exist for task-based medical image quality assessment, but almost exclusively for diagnostic imaging tasks. As opposed to disease diagnosis, the task for image observers in radiation therapy is to utilize the available images to design and deliver a radiation dose which maximizes patient disease control while minimizing normal tissue damage. The purpose of this study was to design and implement a new computer simulation model observer to enable task-based image quality assessment in radiation therapy. Methods: A modular computer simulation framework was developed to resemble the radiotherapy observer by simulating an end-to-end radiation therapy treatment. Given images and the ground-truth organ boundaries from a numerical phantom as inputs, the framework simulates an external beam radiation therapy treatment and quantifies patient treatment outcomes using the previously defined therapeutic operating characteristic (TOC) curve. As a preliminary demonstration, TOC curves were calculated for various CT acquisition and reconstruction parameters, with the goal of assessing and optimizing simulation CT image quality for radiation therapy. Sources of randomness and bias within the system were analyzed. Results: The relationship between CT imaging dose and patient treatment outcome was objectively quantified in terms of a singular value, the area under the TOC (AUTOC) curve. The AUTOC decreases more rapidly for low-dose imaging protocols. AUTOC variation introduced by the dose optimization algorithm was approximately 0.02%, at the 95% confidence interval. Conclusion: A model observer has been developed and implemented to assess image quality based on radiation therapy treatment efficacy. It enables objective determination of appropriate imaging parameter values (e.g. imaging dose). Framework flexibility allows for incorporation

  8. Simulation and measurement of total ionizing dose radiation induced image lag increase in pinned photodiode CMOS image sensors

    Liu, Jing [School of Materials Science and Engineering, Xiangtan University, Hunan (China); State Key Laboratory of Intense Pulsed Irradiation Simulation and Effect, Northwest Institute of Nuclear Technology, P.O.Box 69-10, Xi’an (China); Chen, Wei, E-mail: chenwei@nint.ac.cn [State Key Laboratory of Intense Pulsed Irradiation Simulation and Effect, Northwest Institute of Nuclear Technology, P.O.Box 69-10, Xi’an (China); Wang, Zujun, E-mail: wangzujun@nint.ac.cn [State Key Laboratory of Intense Pulsed Irradiation Simulation and Effect, Northwest Institute of Nuclear Technology, P.O.Box 69-10, Xi’an (China); Xue, Yuanyuan; Yao, Zhibin; He, Baoping; Ma, Wuying; Jin, Junshan; Sheng, Jiangkun; Dong, Guantao [State Key Laboratory of Intense Pulsed Irradiation Simulation and Effect, Northwest Institute of Nuclear Technology, P.O.Box 69-10, Xi’an (China)

    2017-06-01

    This paper presents an investigation of total ionizing dose (TID) induced image lag sources in pinned photodiodes (PPD) CMOS image sensors based on radiation experiments and TCAD simulation. The radiation experiments have been carried out at the Cobalt −60 gamma-ray source. The experimental results show the image lag degradation is more and more serious with increasing TID. Combining with the TCAD simulation results, we can confirm that the junction of PPD and transfer gate (TG) is an important region forming image lag during irradiation. These simulations demonstrate that TID can generate a potential pocket leading to incomplete transfer.

  9. Planning of nets

    Carberry, M

    1996-01-01

    The paper is about the planning of nets in areas of low density like it is the case of the rural areas. The author includes economic and technological aspects, planning of nets, demands and management among others

  10. Annotating Coloured Petri Nets

    Lindstrøm, Bo; Wells, Lisa Marie

    2002-01-01

    Coloured Petri nets (CP-nets) can be used for several fundamentally different purposes like functional analysis, performance analysis, and visualisation. To be able to use the corresponding tool extensions and libraries it is sometimes necessary to include extra auxiliary information in the CP......-net. An example of such auxiliary information is a counter which is associated with a token to be able to do performance analysis. Modifying colour sets and arc inscriptions in a CP-net to support a specific use may lead to creation of several slightly different CP-nets – only to support the different uses...... of the same basic CP-net. One solution to this problem is that the auxiliary information is not integrated into colour sets and arc inscriptions of a CP-net, but is kept separately. This makes it easy to disable this auxiliary information if a CP-net is to be used for another purpose. This paper proposes...

  11. The Premar Code for the Monte Carlo Simulation of Radiation Transport In the Atmosphere

    Cupini, E.; Borgia, M.G.; Premuda, M.

    1997-03-01

    The Montecarlo code PREMAR is described, which allows the user to simulate the radiation transport in the atmosphere, in the ultraviolet-infrared frequency interval. A plan multilayer geometry is at present foreseen by the code, witch albedo possibility at the lower boundary surface. For a given monochromatic point source, the main quantities computed by the code are the absorption spatial distributions of aerosol and molecules, together with the related atmospheric transmittances. Moreover, simulation of of Lidar experiments are foreseen by the code, the source and telescope fields of view being assigned. To build-up the appropriate probability distributions, an input data library is assumed to be read by the code. For this purpose the radiance-transmittance LOWTRAN-7 code has been conveniently adapted as a source of the library so as to exploit the richness of information of the code for a large variety of atmospheric simulations. Results of applications of the PREMAR code are finally presented, with special reference to simulations of Lidar system and radiometer experiments carried out at the Brasimone ENEA Centre by the Environment Department

  12. Coupled eco-hydrology and biogeochemistry algorithms enable the simulation of water table depth effects on boreal peatland net CO2 exchange

    Mezbahuddin, Mohammad; Grant, Robert F.; Flanagan, Lawrence B.

    2017-12-01

    Water table depth (WTD) effects on net ecosystem CO2 exchange of boreal peatlands are largely mediated by hydrological effects on peat biogeochemistry and the ecophysiology of peatland vegetation. The lack of representation of these effects in carbon models currently limits our predictive capacity for changes in boreal peatland carbon deposits under potential future drier and warmer climates. We examined whether a process-level coupling of a prognostic WTD with (1) oxygen transport, which controls energy yields from microbial and root oxidation-reduction reactions, and (2) vascular and nonvascular plant water relations could explain mechanisms that control variations in net CO2 exchange of a boreal fen under contrasting WTD conditions, i.e., shallow vs. deep WTD. Such coupling of eco-hydrology and biogeochemistry algorithms in a process-based ecosystem model, ecosys, was tested against net ecosystem CO2 exchange measurements in a western Canadian boreal fen peatland over a period of drier-weather-driven gradual WTD drawdown. A May-October WTD drawdown of ˜ 0.25 m from 2004 to 2009 hastened oxygen transport to microbial and root surfaces, enabling greater microbial and root energy yields and peat and litter decomposition, which raised modeled ecosystem respiration (Re) by 0.26 µmol CO2 m-2 s-1 per 0.1 m of WTD drawdown. It also augmented nutrient mineralization, and hence root nutrient availability and uptake, which resulted in improved leaf nutrient (nitrogen) status that facilitated carboxylation and raised modeled vascular gross primary productivity (GPP) and plant growth. The increase in modeled vascular GPP exceeded declines in modeled nonvascular (moss) GPP due to greater shading from increased vascular plant growth and moss drying from near-surface peat desiccation, thereby causing a net increase in modeled growing season GPP by 0.39 µmol CO2 m-2 s-1 per 0.1 m of WTD drawdown. Similar increases in GPP and Re caused no significant WTD effects on modeled

  13. Coupled eco-hydrology and biogeochemistry algorithms enable the simulation of water table depth effects on boreal peatland net CO2 exchange

    M. Mezbahuddin

    2017-12-01

    Full Text Available Water table depth (WTD effects on net ecosystem CO2 exchange of boreal peatlands are largely mediated by hydrological effects on peat biogeochemistry and the ecophysiology of peatland vegetation. The lack of representation of these effects in carbon models currently limits our predictive capacity for changes in boreal peatland carbon deposits under potential future drier and warmer climates. We examined whether a process-level coupling of a prognostic WTD with (1 oxygen transport, which controls energy yields from microbial and root oxidation–reduction reactions, and (2 vascular and nonvascular plant water relations could explain mechanisms that control variations in net CO2 exchange of a boreal fen under contrasting WTD conditions, i.e., shallow vs. deep WTD. Such coupling of eco-hydrology and biogeochemistry algorithms in a process-based ecosystem model, ecosys, was tested against net ecosystem CO2 exchange measurements in a western Canadian boreal fen peatland over a period of drier-weather-driven gradual WTD drawdown. A May–October WTD drawdown of  ∼  0.25 m from 2004 to 2009 hastened oxygen transport to microbial and root surfaces, enabling greater microbial and root energy yields and peat and litter decomposition, which raised modeled ecosystem respiration (Re by 0.26 µmol CO2 m−2 s−1 per 0.1 m of WTD drawdown. It also augmented nutrient mineralization, and hence root nutrient availability and uptake, which resulted in improved leaf nutrient (nitrogen status that facilitated carboxylation and raised modeled vascular gross primary productivity (GPP and plant growth. The increase in modeled vascular GPP exceeded declines in modeled nonvascular (moss GPP due to greater shading from increased vascular plant growth and moss drying from near-surface peat desiccation, thereby causing a net increase in modeled growing season GPP by 0.39 µmol CO2 m−2 s−1 per 0.1 m of WTD drawdown. Similar increases in

  14. The accuracy of seminumerical reionization models in comparison with radiative transfer simulations

    Hutter, Anne

    2018-06-01

    We have developed a modular seminumerical code that computes the time and spatially dependent ionization of neutral hydrogen (H I), neutral (He I), and single-ionized helium (He II) in the intergalactic medium (IGM). The model accounts for recombinations and provides different descriptions for the photoionization rate that are used to calculate the residual H I} fraction in ionized regions. We compare different seminumerical reionization schemes to a radiative transfer (RT) simulation. We use the RT simulation as a benchmark, and find that the seminumerical approaches produce similar H II and He II morphologies and power spectra of the H I 21 cm signal throughout reionization. As we do not track partial ionization of He II, the extent of the double-ionized helium (He III) regions is consistently smaller. In contrast to previous comparison projects, the ionizing emissivity in our seminumerical scheme is not adjusted to reproduce the redshift evolution of the RT simulation, but directly derived from the RT simulation spectra. Among schemes that identify the ionized regions by the ratio of the number of ionization and absorption events on different spatial smoothing scales, we find those that mark the entire sphere as ionized when the ionization criterion is fulfilled to result in significantly accelerated reionization compared to the RT simulation. Conversely, those that flag only the central cell as ionized yield very similar but slightly delayed redshift evolution of reionization, with up to 20 per cent ionizing photons lost. Despite the overall agreement with the RT simulation, our results suggest that constraining ionizing emissivity-sensitive parameters from seminumerical galaxy formation-reionization models are subject to photon nonconservation.

  15. The FluxCompensator: Making Radiative Transfer Models of Hydrodynamical Simulations Directly Comparable to Real Observations

    Koepferl, Christine M.; Robitaille, Thomas P., E-mail: koepferl@usm.lmu.de [Max Planck Institute for Astronomy, Königstuhl 17, D-69117 Heidelberg (Germany)

    2017-11-01

    When modeling astronomical objects throughout the universe, it is important to correctly treat the limitations of the data, for instance finite resolution and sensitivity. In order to simulate these effects, and to make radiative transfer models directly comparable to real observations, we have developed an open-source Python package called the FluxCompensator that enables the post-processing of the output of 3D Monte Carlo radiative transfer codes, such as Hyperion. With the FluxCompensator, realistic synthetic observations can be generated by modeling the effects of convolution with arbitrary point-spread functions, transmission curves, finite pixel resolution, noise, and reddening. Pipelines can be applied to compute synthetic observations that simulate observatories, such as the Spitzer Space Telescope or the Herschel Space Observatory . Additionally, this tool can read in existing observations (e.g., FITS format) and use the same settings for the synthetic observations. In this paper, we describe the package as well as present examples of such synthetic observations.

  16. The FluxCompensator: Making Radiative Transfer Models of Hydrodynamical Simulations Directly Comparable to Real Observations

    Koepferl, Christine M.; Robitaille, Thomas P.

    2017-11-01

    When modeling astronomical objects throughout the universe, it is important to correctly treat the limitations of the data, for instance finite resolution and sensitivity. In order to simulate these effects, and to make radiative transfer models directly comparable to real observations, we have developed an open-source Python package called the FluxCompensator that enables the post-processing of the output of 3D Monte Carlo radiative transfer codes, such as Hyperion. With the FluxCompensator, realistic synthetic observations can be generated by modeling the effects of convolution with arbitrary point-spread functions, transmission curves, finite pixel resolution, noise, and reddening. Pipelines can be applied to compute synthetic observations that simulate observatories, such as the Spitzer Space Telescope or the Herschel Space Observatory. Additionally, this tool can read in existing observations (e.g., FITS format) and use the same settings for the synthetic observations. In this paper, we describe the package as well as present examples of such synthetic observations.

  17. Electronic excitations and their effect on the interionic forces in simulations of radiation damage in metals

    Race, C P; Mason, D R; Sutton, A P

    2009-01-01

    Using time-dependent tight-binding simulations of radiation damage cascades in a model metal we directly investigate the nature of the excitations of a system of quantum mechanical electrons in response to the motion of a set of classical ions. We furthermore investigate the effect of these excitations on the attractive electronic forces between the ions. We find that the electronic excitations are well described by a Fermi-Dirac distribution at some elevated temperature, even in the absence of the direct electron-electron interactions that would be required in order to thermalize a non-equilibrium distribution. We explain this result in terms of the spectrum of characteristic frequencies of the ionic motion. Decomposing the electronic force into four well-defined components within the basis of instantaneous electronic eigenstates, we find that the effect of accumulated excitations in weakening the interionic bonds is mostly (95%) accounted for by a thermal model for the electronic excitations. This result justifies the use of the simplifying assumption of a thermalized electron system in simulations of radiation damage with an electronic temperature dependence and in the development of temperature-dependent classical potentials.

  18. Electronic excitations and their effect on the interionic forces in simulations of radiation damage in metals.

    Race, C P; Mason, D R; Sutton, A P

    2009-03-18

    Using time-dependent tight-binding simulations of radiation damage cascades in a model metal we directly investigate the nature of the excitations of a system of quantum mechanical electrons in response to the motion of a set of classical ions. We furthermore investigate the effect of these excitations on the attractive electronic forces between the ions. We find that the electronic excitations are well described by a Fermi-Dirac distribution at some elevated temperature, even in the absence of the direct electron-electron interactions that would be required in order to thermalize a non-equilibrium distribution. We explain this result in terms of the spectrum of characteristic frequencies of the ionic motion. Decomposing the electronic force into four well-defined components within the basis of instantaneous electronic eigenstates, we find that the effect of accumulated excitations in weakening the interionic bonds is mostly (95%) accounted for by a thermal model for the electronic excitations. This result justifies the use of the simplifying assumption of a thermalized electron system in simulations of radiation damage with an electronic temperature dependence and in the development of temperature-dependent classical potentials.

  19. Monte Carlo simulation of the sequential probability ratio test for radiation monitoring

    Coop, K.L.

    1984-01-01

    A computer program simulates the Sequential Probability Ratio Test (SPRT) using Monte Carlo techniques. The program, SEQTEST, performs random-number sampling of either a Poisson or normal distribution to simulate radiation monitoring data. The results are in terms of the detection probabilities and the average time required for a trial. The computed SPRT results can be compared with tabulated single interval test (SIT) values to determine the better statistical test for particular monitoring applications. Use of the SPRT in a hand-and-foot alpha monitor shows that the SPRT provides better detection probabilities while generally requiring less counting time. Calculations are also performed for a monitor where the SPRT is not permitted to the take longer than the single interval test. Although the performance of the SPRT is degraded by this restriction, the detection probabilities are still similar to the SIT values, and average counting times are always less than 75% of the SIT time. Some optimal conditions for use of the SPRT are described. The SPRT should be the test of choice in many radiation monitoring situations. 6 references, 8 figures, 1 table

  20. HAW simulation experiments with cobalt-60 radiation sources in the Asse salt mine

    Rothfuchs, T.; Wieczorek, K.; Feddersen, H.K.

    1986-01-01

    The report describes the experimental work and the measured data of the joint German-American project for the HAW simulation experiment with cobalt-60 radiation sources in the Asse salt mine, covering the period up to the end of the third quarter 1986. The experiment is intended to yield information on the synergistic effects of heat and ionizing radiation on the salt rock under representative waste repository conditions. The investigations aim at the migration, release, and radiolytic decomposition of the water and gas components in the rock salt, and at the thermally induced strain and deformation processes. In addition, corrosion tests are planned to be made on various container test materials, and analyses of salt rock core samples for assessing the effect of heat and radiation on the rock. The report in hand presents all data obtained during the experiment. The results of the subsequent evaluation and verification studies will be presented in another report, the programme being given in an annex to the report in hand. (orig./RB) [de

  1. A Radiative Transfer Modeling Methodology in Gas-Liquid Multiphase Flow Simulations

    Gautham Krishnamoorthy

    2014-01-01

    Full Text Available A methodology for performing radiative transfer calculations in computational fluid dynamic simulations of gas-liquid multiphase flows is presented. By considering an externally irradiated bubble column photoreactor as our model system, the bubble scattering coefficients were determined through add-on functions by employing as inputs the bubble volume fractions, number densities, and the fractional contribution of each bubble size to the bubble volume from four different multiphase modeling options. The scattering coefficient profiles resulting from the models were significantly different from one another and aligned closely with their predicted gas-phase volume fraction distributions. The impacts of the multiphase modeling option, initial bubble diameter, and gas flow rates on the radiation distribution patterns within the reactor were also examined. An increase in air inlet velocities resulted in an increase in the fraction of larger sized bubbles and their contribution to the scattering coefficient. However, the initial bubble sizes were found to have the strongest impact on the radiation field.

  2. Modeling and simulations of radiative blast wave driven Rayleigh-Taylor instability experiments

    Shimony, Assaf; Huntington, Channing M.; Trantham, Matthew; Malamud, Guy; Elbaz, Yonatan; Kuranz, Carolyn C.; Drake, R. Paul; Shvarts, Dov

    2017-10-01

    Recent experiments at the National Ignition Facility measured the growth of Rayleigh-Taylor RT instabilities driven by radiative blast waves, relevant to astrophysics and other HEDP systems. We constructed a new Buoyancy-Drag (BD) model, which accounts for the ablation effect on both bubble and spike. This ablation effect is accounted for by using the potential flow model ]Oron et al PoP 1998], adding another term to the classical BD formalism: βDuA / u , where β the Takabe constant, D the drag term, uA the ablation velocity and uthe instability growth velocity. The model results are compared with the results of experiments and 2D simulations using the CRASH code, with nominal radiation or reduced foam opacity (by a factor of 1000). The ablation constant of the model, βb / s, for the bubble and for the spike fronts, are calibrated using the results of the radiative shock experiments. This work is funded by the Lawrence Livermore National Laboratory under subcontract B614207, and was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract No. DE-AC52-07NA27344.

  3. Evaluation of Three Parametric Models for Estimating Directional Thermal Radiation from Simulation, Airborne, and Satellite Data

    Xiangyang Liu

    2018-03-01

    Full Text Available An appropriate model to correct thermal radiation anisotropy is important for the wide applications of land surface temperature (LST. This paper evaluated the performance of three published directional thermal radiation models—the Roujean–Lagouarde (RL model, the Bidirectional Reflectance Distribution Function (BRDF model, and the Vinnikov model—at canopy and pixel scale using simulation, airborne, and satellite data. The results at canopy scale showed that (1 the three models could describe directional anisotropy well and the Vinnikov model performed the best, especially for erectophile canopy or low leaf area index (LAI; (2 the three models reached the highest fitting accuracy when the LAI varied from 1 to 2; and (3 the capabilities of the three models were all restricted by the hotspot effect, plant height, plant spacing, and three-dimensional structure. The analysis at pixel scale indicated a consistent result that the three models presented a stable effect both on verification and validation, but the Vinnikov model had the best ability in the erectophile canopy (savannas and grassland and low LAI (barren or sparsely vegetated areas. Therefore, the Vinnikov model was calibrated for different land cover types to instruct the angular correction of LST. Validation with the Surface Radiation Budget Network (SURFRAD-measured LST demonstrated that the root mean square (RMSE of the Moderate Resolution Imaging Spectroradiometer (MODIS LST product could be decreased by 0.89 K after angular correction. In addition, the corrected LST showed better spatial uniformity and higher angular correlation.

  4. A simulation technique for 3D MR-guided acoustic radiation force imaging

    Payne, Allison; Bever, Josh de; Farrer, Alexis; Coats, Brittany; Parker, Dennis L.; Christensen, Douglas A.

    2015-01-01

    Purpose: In magnetic resonance-guided focused ultrasound (MRgFUS) therapies, the in situ characterization of the focal spot location and quality is critical. MR acoustic radiation force imaging (MR-ARFI) is a technique that measures the tissue displacement caused by the radiation force exerted by the ultrasound beam. This work presents a new technique to model the displacements caused by the radiation force of an ultrasound beam in a homogeneous tissue model. Methods: When a steady-state point-source force acts internally in an infinite homogeneous medium, the displacement of the material in all directions is given by the Somigliana elastostatic tensor. The radiation force field, which is caused by absorption and reflection of the incident ultrasound intensity pattern, will be spatially distributed, and the tensor formulation takes the form of a convolution of a 3D Green’s function with the force field. The dynamic accumulation of MR phase during the ultrasound pulse can be theoretically accounted for through a time-of-arrival weighting of the Green’s function. This theoretical model was evaluated experimentally in gelatin phantoms of varied stiffness (125-, 175-, and 250-bloom). The acoustic and mechanical properties of the phantoms used as parameters of the model were measured using independent techniques. Displacements at focal depths of 30- and 45-mm in the phantoms were measured by a 3D spin echo MR-ARFI segmented-EPI sequence. Results: The simulated displacements agreed with the MR-ARFI measured displacements for all bloom values and focal depths with a normalized RMS difference of 0.055 (range 0.028–0.12). The displacement magnitude decreased and the displacement pattern broadened with increased bloom value for both focal depths, as predicted by the theory. Conclusions: A new technique that models the displacements caused by the radiation force of an ultrasound beam in a homogeneous tissue model theory has been rigorously validated through comparison

  5. Integrated Radiation Transport and Nuclear Fuel Performance for Assembly-Level Simulations

    Clarno, Kevin T [ORNL; Hamilton, Steven P [ORNL; Philip, Bobby [ORNL; Berrill, Mark A [ORNL; Sampath, Rahul S [ORNL; Allu, Srikanth [ORNL; Pugmire, Dave [ORNL; Dilts, Gary [Los Alamos National Laboratory (LANL); Banfield, James E [ORNL

    2012-02-01

    The Advanced Multi-Physics (AMP) Nuclear Fuel Performance code (AMPFuel) is focused on predicting the temperature and strain within a nuclear fuel assembly to evaluate the performance and safety of existing and advanced nuclear fuel bundles within existing and advanced nuclear reactors. AMPFuel was extended to include an integrated nuclear fuel assembly capability for (one-way) coupled radiation transport and nuclear fuel assembly thermo-mechanics. This capability is the initial step toward incorporating an improved predictive nuclear fuel assembly modeling capability to accurately account for source-terms and boundary conditions of traditional (single-pin) nuclear fuel performance simulation, such as the neutron flux distribution, coolant conditions, and assembly mechanical stresses. A novel scheme is introduced for transferring the power distribution from the Scale/Denovo (Denovo) radiation transport code (structured, Cartesian mesh with smeared materials within each cell) to AMPFuel (unstructured, hexagonal mesh with a single material within each cell), allowing the use of a relatively coarse spatial mesh (10 million elements) for the radiation transport and a fine spatial mesh (3.3 billion elements) for thermo-mechanics with very little loss of accuracy. In addition, a new nuclear fuel-specific preconditioner was developed to account for the high aspect ratio of each fuel pin (12 feet axially, but 1 4 inches in diameter) with many individual fuel regions (pellets). With this novel capability, AMPFuel was used to model an entire 17 17 pressurized water reactor fuel assembly with many of the features resolved in three dimensions (for thermo-mechanics and/or neutronics), including the fuel, gap, and cladding of each of the 264 fuel pins; the 25 guide tubes; the top and bottom structural regions; and the upper and lower (neutron) reflector regions. The final, full assembly calculation was executed on Jaguar using 40,000 cores in under 10 hours to model over 162

  6. Interface methods for hybrid Monte Carlo-diffusion radiation-transport simulations

    Densmore, Jeffery D.

    2006-01-01

    Discrete diffusion Monte Carlo (DDMC) is a technique for increasing the efficiency of Monte Carlo simulations in diffusive media. An important aspect of DDMC is the treatment of interfaces between diffusive regions, where DDMC is used, and transport regions, where standard Monte Carlo is employed. Three previously developed methods exist for treating transport-diffusion interfaces: the Marshak interface method, based on the Marshak boundary condition, the asymptotic interface method, based on the asymptotic diffusion-limit boundary condition, and the Nth-collided source technique, a scheme that allows Monte Carlo particles to undergo several collisions in a diffusive region before DDMC is used. Numerical calculations have shown that each of these interface methods gives reasonable results as part of larger radiation-transport simulations. In this paper, we use both analytic and numerical examples to compare the ability of these three interface techniques to treat simpler, transport-diffusion interface problems outside of a more complex radiation-transport calculation. We find that the asymptotic interface method is accurate regardless of the angular distribution of Monte Carlo particles incident on the interface surface. In contrast, the Marshak boundary condition only produces correct solutions if the incident particles are isotropic. We also show that the Nth-collided source technique has the capacity to yield accurate results if spatial cells are optically small and Monte Carlo particles are allowed to undergo many collisions within a diffusive region before DDMC is employed. These requirements make the Nth-collided source technique impractical for realistic radiation-transport calculations

  7. A hybrid transport-diffusion method for Monte Carlo radiative-transfer simulations

    Densmore, Jeffery D.; Urbatsch, Todd J.; Evans, Thomas M.; Buksas, Michael W.

    2007-01-01

    Discrete Diffusion Monte Carlo (DDMC) is a technique for increasing the efficiency of Monte Carlo particle-transport simulations in diffusive media. If standard Monte Carlo is used in such media, particle histories will consist of many small steps, resulting in a computationally expensive calculation. In DDMC, particles take discrete steps between spatial cells according to a discretized diffusion equation. Each discrete step replaces many small Monte Carlo steps, thus increasing the efficiency of the simulation. In addition, given that DDMC is based on a diffusion equation, it should produce accurate solutions if used judiciously. In practice, DDMC is combined with standard Monte Carlo to form a hybrid transport-diffusion method that can accurately simulate problems with both diffusive and non-diffusive regions. In this paper, we extend previously developed DDMC techniques in several ways that improve the accuracy and utility of DDMC for nonlinear, time-dependent, radiative-transfer calculations. The use of DDMC in these types of problems is advantageous since, due to the underlying linearizations, optically thick regions appear to be diffusive. First, we employ a diffusion equation that is discretized in space but is continuous in time. Not only is this methodology theoretically more accurate than temporally discretized DDMC techniques, but it also has the benefit that a particle's time is always known. Thus, there is no ambiguity regarding what time to assign a particle that leaves an optically thick region (where DDMC is used) and begins transporting by standard Monte Carlo in an optically thin region. Also, we treat the interface between optically thick and optically thin regions with an improved method, based on the asymptotic diffusion-limit boundary condition, that can produce accurate results regardless of the angular distribution of the incident Monte Carlo particles. Finally, we develop a technique for estimating radiation momentum deposition during the

  8. Simulation of TGF-Beta Activation by Low-Dose HZE Radiation in a Cell Culture

    Plante, Ianik; Cucinotta, Francis A.

    2009-01-01

    High charge (Z) and energy (E) (HZE) nuclei comprised in the galactic cosmic rays are main contributors to space radiation risk. They induce many lesions in living matter such as non-specific oxidative damage and the double-strand breaks (DSBs), which are considered key precursors of early and late effects of radiation. There is increasing evidence that cells respond collectively rather than individually to radiation, suggesting the importance of cell signaling1. The transforming growth factor (TGF ) is a signaling peptide that is expressed in nearly all cell type and regulates a large array of cellular processes2. TGF have been shown to mediate cellular response to DNA damage3 and to induce apoptosis in non-irradiated cells cocultured with irradiated cells4. TFG molecules are secreted by cells in an inactive complex known as the latency-associated peptide (LAP). TGF is released from the LAP by a conformational change triggered by proteases, thrombospondin-1, integrins, acidic conditions and .OH radical5. TGF then binds to cells receptors and activates a cascade of events mediated by Smad proteins6, which might interfere with the repair of DNA. Meanwhile, increasingly sophisticated Brownian Dynamics (BD) algorithms have appeared recently in the literature7 and can be applied to study the interaction of molecules with receptors. These BD computer models have contributed to the elucidation of signal transduction, ligand accumulation and autocrine loops in the epidermal growth factor (EGF) and its receptor (EFGR) system8. To investigate the possible roles of TGF in an irradiated cell culture, our Monte-Carlo simulation codes of the radiation track structure9 will be used to calculate the activation of TFG triggered by .OH produced by low doses of HZE ions. The TGF molecules will then be followed by a BD algorithm in a medium representative of a cell culture to estimate the number of activated receptors.

  9. Monte Carlo generator ELRADGEN 2.0 for simulation of radiative events in elastic ep-scattering of polarized particles

    Akushevich, I.; Filoti, O. F.; Ilyichev, A.; Shumeiko, N.

    2012-07-01

    The structure and algorithms of the Monte Carlo generator ELRADGEN 2.0 designed to simulate radiative events in polarized ep-scattering are presented. The full set of analytical expressions for the QED radiative corrections is presented and discussed in detail. Algorithmic improvements implemented to provide faster simulation of hard real photon events are described. Numerical tests show high quality of generation of photonic variables and radiatively corrected cross section. The comparison of the elastic radiative tail simulated within the kinematical conditions of the BLAST experiment at MIT BATES shows a good agreement with experimental data. Catalogue identifier: AELO_v1_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AELO_v1_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: Standard CPC license, http://cpc.cs.qub.ac.uk/licence/licence.html No. of lines in distributed program, including test data, etc.: 1299 No. of bytes in distributed program, including test data, etc.: 11 348 Distribution format: tar.gz Programming language: FORTRAN 77 Computer: All Operating system: Any RAM: 1 MB Classification: 11.2, 11.4 Nature of problem: Simulation of radiative events in polarized ep-scattering. Solution method: Monte Carlo simulation according to the distributions of the real photon kinematic variables that are calculated by the covariant method of QED radiative correction estimation. The approach provides rather fast and accurate generation. Running time: The simulation of 108 radiative events for itest:=1 takes up to 52 seconds on Pentium(R) Dual-Core 2.00 GHz processor.

  10. Radiation belt electron acceleration during the 17 March 2015 geomagnetic storm: Observations and simulations

    Li, W.; Ma, Q.; Thorne, R. M.; Bortnik, J.; Zhang, X.-J.

    2016-01-01

    Various physical processes are known to cause acceleration, loss, and transport of energetic electrons in the Earth's radiation belts, but their quantitative roles in different time and space need further investigation. During the largest storm over the past decade (17 March 2015), relativistic electrons experienced fairly rapid acceleration up to ~7 MeV within 2 days after an initial substantial dropout, as observed by Van Allen Probes. In the present paper, we evaluate the relative roles of various physical processes during the recovery phase of this large storm using a 3-D diffusion simulation. By quantitatively comparing the observed and simulated electron evolution, we found that chorus plays a critical role in accelerating electrons up to several MeV near the developing peak location and produces characteristic flat-top pitch angle distributions. By only including radial diffusion, the simulation underestimates the observed electron acceleration, while radial diffusion plays an important role in redistributing electrons and potentially accelerates them to even higher energies. Moreover, plasmaspheric hiss is found to provide efficient pitch angle scattering losses for hundreds of keV electrons, while its scattering effect on > 1 MeV electrons is relatively slow. Although an additional loss process is required to fully explain the overestimated electron fluxes at multi-MeV, the combined physical processes of radial diffusion and pitch angle and energy diffusion by chorus and hiss reproduce the observed electron dynamics remarkably well, suggesting that quasi-linear diffusion theory is reasonable to evaluate radiation belt electron dynamics during this big storm.

  11. Using simulation for intervention design in radiating environment: first evaluation of NARVEOS

    Thevenon, Jean-Bernard; Lopez, Loic [Euriware, 1 place des Freres Montgolfier, 78044 Guyancourt Cedex (France); Chabal, Caroline; Idasiak, Jean-Marc [CEA-DEN, Dismantling and Operations Support Department, CEA Valrho, BP 17171, 30207 Bagnols-sur-Ceze (France); Chodorge, Laurent [CEA-LIST, Virtual Reality Cognitic and Interface Service, CEA-FAR, Bat 38, 92265 Fontenay-aux-Roses (France); Desbats, Philippe [CEA-LIST, Intelligent Systems and Technologies Department, CEA-Saclay, Bat 476, 91191 Gif-sur-Yvette (France)

    2009-06-15

    Interventions design in radiating environment must bring answers to technical and economical constraint on one hand and, on the other hand, to radiation protection principles and rules. Simulation is a key point for a good understanding of the scene and for testing hypothesis. The paper presents how a simulation tool (called NARVEOS), based on Virtual Reality technology and on fast coupling between geometries descriptions and a solver, can provide significant support to engineers in charge of scenario design. Besides feasibility study scenario design for one-shot project such as dismantling operations, such a tool is well adapted also for dose projection reduction on regular operations such as maintenance and outage. The technologies used to interactively and simultaneously compute the dose estimate within a CAD model are presented. By using CAD model and available radiological data (source term description), the software allows simulating the evolution of the different features of the digital mock-up (virtual human workers, robots, sources, biological protections, etc.) and evaluating the accessibility issues using interactivity with the end-user. Thanks to this software, users can virtually test the operation feasibility, optimise the costs and estimate the dose rate according to ALARA principle. This tool offers new perspectives for studies, costs and deadlines management of decommissioning projects, as well as for communication between project teams, providers and safety authority about integrated dose optimisation. The first results of NARVEOS will be reported through several applications carried out within on-going decommissioning projects in several nuclear sites. Some evaluation tests are also presented and discussed. (authors)

  12. Trend of surface solar radiation over Asia simulated by aerosol transport-climate model

    Takemura, T.; Ohmura, A.

    2009-12-01

    . Continuous hindcast simulation during the last several decades is done to compare with surface radiation measurements. Cause of the global dimming and brightening is separated into the aerosol direct and indirect effects from the simulation. Acknowledgments. The simulation in this study was performed on the NIES supercomputer system (NEC SX-8R). This study is partly supported by the Global Environment Research Fund (RF-091) by the Ministry of the Environment of Japan, Grant-in-Aid for Young Scientist (21681001) by the Ministry of Education, Culture, Sports, Science, and Technology of Japan, and Mitsui & Co., Ltd. Environment Fund (R08-D035). References Ohmura, A. (2009), J. Geophys. Res., 114, doi:10.1029/2008JD011290. Takemura, T., et al. (2000), J. Geophys. Res., 105, 17853-17873. Takemura, T., et al. (2002), J. Climate, 15, 333-352. Takemura, T., et al. (2005), J. Geophys. Res., 110, doi:10.1029/2004JD005029. Takemura, T., et al. (2009), Atmos. Chem. Phys., 9, 3061-3073. Wild, M. (2009), J. Geophys. Res., 114, doi:10.1029/2008JD011470.

  13. Clinical evaluation of a commercial orthopedic metal artifact reduction tool for CT simulations in radiation therapy

    Li Hua; Noel, Camille; Chen, Haijian; Harold Li, H.; Low, Daniel; Moore, Kevin; Klahr, Paul; Michalski, Jeff; Gay, Hiram A.; Thorstad, Wade; Mutic, Sasa [Department of Radiation Oncology, Washington University, St. Louis, Missouri 63110 (United States); Department of Radiation Oncology, University of California Los Angeles, Los Angeles, California 90095 (United States); Department of Radiation Oncology, University of California San Diego, San Diego, California 92093 (United States); Philips Healthcare System, Cleveland, Ohio 44143 (United States); Department of Radiation Oncology, Washington University, St. Louis, Missouri 63110 (United States)

    2012-12-15

    Purpose: Severe artifacts in kilovoltage-CT simulation images caused by large metallic implants can significantly degrade the conspicuity and apparent CT Hounsfield number of targets and anatomic structures, jeopardize the confidence of anatomical segmentation, and introduce inaccuracies into the radiation therapy treatment planning process. This study evaluated the performance of the first commercial orthopedic metal artifact reduction function (O-MAR) for radiation therapy, and investigated its clinical applications in treatment planning. Methods: Both phantom and clinical data were used for the evaluation. The CIRS electron density phantom with known physical (and electron) density plugs and removable titanium implants was scanned on a Philips Brilliance Big Bore 16-slice CT simulator. The CT Hounsfield numbers of density plugs on both uncorrected and O-MAR corrected images were compared. Treatment planning accuracy was evaluated by comparing simulated dose distributions computed using the true density images, uncorrected images, and O-MAR corrected images. Ten CT image sets of patients with large hip implants were processed with the O-MAR function and evaluated by two radiation oncologists using a five-point score for overall image quality, anatomical conspicuity, and CT Hounsfield number accuracy. By utilizing the same structure contours delineated from the O-MAR corrected images, clinical IMRT treatment plans for five patients were computed on the uncorrected and O-MAR corrected images, respectively, and compared. Results: Results of the phantom study indicated that CT Hounsfield number accuracy and noise were improved on the O-MAR corrected images, especially for images with bilateral metal implants. The {gamma} pass rates of the simulated dose distributions computed on the uncorrected and O-MAR corrected images referenced to those of the true densities were higher than 99.9% (even when using 1% and 3 mm distance-to-agreement criterion), suggesting that dose

  14. Radiative Transfer Simulations of Cosmic Reionization With Pop II and III Stars

    Trac, Hy; Cen, Renyue

    2008-03-01

    We have simulated 3 large volume, high resolution realizations of cosmic reionization using a hybrid code that combines a N-body algorithm for dark matter, prescriptions for baryons and star formation, and a radiative transfer algorithm for ionizing photons. Our largest simulation, with 24 billion particles in a 100 Mpc/h box, simultaneously provides (1) the mass resolution needed to resolve dark matter halos down to a virial temperatures of 104 K and (2) the volume needed to fairly sample highly biased sources and large HII regions. We model the stellar initial mass function (IMF) by following the spatially dependent gas metallicity evolution, and distinguish between the first generation (Population III) stars and the second generation (Population II) stars. The Population III stars, with a top-heavy IMF, produce an order of magnitude more ionizing photons at high redshifts z>~10, resulting in a more extended reionization. In our simulations, complete overlap of HII regions occurs at z~6.5 and the computed mass and volume weighted residual HI fractions at 5measurements from SDSS. The values for the Thomson optical depth are consistent within 1-σ of the current best-fit value from the WMAP Year 3 data release.

  15. The Properties of Reconnection Current Sheets in GRMHD Simulations of Radiatively Inefficient Accretion Flows

    Ball, David; Özel, Feryal; Psaltis, Dimitrios; Chan, Chi-Kwan; Sironi, Lorenzo

    2018-02-01

    Non-ideal magnetohydrodynamic (MHD) effects may play a significant role in determining the dynamics, thermal properties, and observational signatures of radiatively inefficient accretion flows onto black holes. In particular, particle acceleration during magnetic reconnection events may influence black hole spectra and flaring properties. We use representative general relativistic magnetohydrodynamic (GRMHD) simulations of black hole accretion flows to identify and explore the structures and properties of current sheets as potential sites of magnetic reconnection. In the case of standard and normal evolution (SANE) disks, we find that in the reconnection sites, the plasma beta ranges from 0.1 to 1000, the magnetization ranges from 10‑4 to 1, and the guide fields are weak compared with the reconnecting fields. In magnetically arrested (MAD) disks, we find typical values for plasma beta from 10‑2 to 103, magnetizations from 10‑3 to 10, and typically stronger guide fields, with strengths comparable to or greater than the reconnecting fields. These are critical parameters that govern the electron energy distribution resulting from magnetic reconnection and can be used in the context of plasma simulations to provide microphysics inputs to global simulations. We also find that ample magnetic energy is available in the reconnection regions to power the fluence of bright X-ray flares observed from the black hole in the center of the Milky Way.

  16. Software simulation and experimental characterisation of a rotationally asymmetrical concentrator under direct and diffuse solar radiation

    Freier, Daria; Muhammad-Sukki, Firdaus; Abu-Bakar, Siti Hawa; Ramirez-Iniguez, Roberto; Abubakar Mas’ud, Abdullahi; Albarracín, Ricardo; Ardila-Rey, Jorge Alfredo; Munir, Abu Bakar; Mohd Yasin, Siti Hajar; Bani, Nurul Aini

    2016-01-01

    Highlights: • The performance of the RADTIRC was analysed under direct and diffuse radiation. • Optical gains of 4.66 under direct and 1.94 under diffuse light were achieved. • The experiments show good agreement with the simulations. • The RADTIRC is an attractive alternative for BICPV systems. - Abstract: Making housing carbon neutral is one of the European Union (EU) targets with the aim to reduce energy consumption and to increase on-site renewable energy generation in the domestic sector. Optical concentrators have a strong potential to minimise the cost of building integrated photovoltaic (BIPV) systems by replacing expensive photovoltaic (PV) material whilst maintaining the same electrical output. In this work, the performance of a recently patented optical concentrator known as the rotationally asymmetrical dielectric totally internally reflective concentrator (RADTIRC) was analysed under direct and diffuse light conditions. The RADTIRC has a geometrical concentration gain of 4.969 and two half acceptance angles of ±40° and ±30° respectively along the two axes. Simulation and experimental work has been carried out to determine the optical concentration gain and the angular response of the concentrator. It was found that the RADTIRC has an optical concentration gain of 4.66 under direct irradiance and 1.94 under diffuse irradiance. The experimental results for the single concentrator showed a reduction in concentration gain of 4.2% when compared with simulation data.

  17. A search for a heavy Majorana neutrino and a radiation damage simulation for the HF detector

    Wetzel, James William

    A search for heavy Majorana neutrinos is performed using an event signature defined by two same-sign muons accompanied by two jets. This search is an extension of previous searches, (L3, DELPHI, CMS, ATLAS), using 19.7 fb -1 of data from the 2012 Large Hadron Collider experimental run collected by the Compact Muon Solenoid experiment. A mass window of 40-500 GeV/ c2 is explored. No excess events above Standard Model backgrounds is observed, and limits are set on the mixing element squared, |VmuN|2, as a function of Majorana neutFnrino mass. The Hadronic Forward (HF) Detector's performance will degrade as a function of the number of particles delivered to the detector over time, a quantity referred to as integrated luminosity and measured in inverse femtobarns (fb-1). In order to better plan detector upgrades, the CMS Forward Calorimetry Task Force (FCAL) group and the CMS Hadronic Calorimeter (HCAL) group have requested that radiation damage be simulated and the subsequent performance of the HF subdetector be studied. The simulation was implemented into both the CMS FastSim and CMS FullSim simulation packages. Standard calorimetry performance metrics were computed and are reported. The HF detector can expect to perform well through the planned delivery of 3000 fb-1.

  18. A voxel-based multiscale model to simulate the radiation response of hypoxic tumors.

    Espinoza, I; Peschke, P; Karger, C P

    2015-01-01

    In radiotherapy, it is important to predict the response of tumors to irradiation prior to the treatment. This is especially important for hypoxic tumors, which are known to be highly radioresistant. Mathematical modeling based on the dose distribution, biological parameters, and medical images may help to improve this prediction and to optimize the treatment plan. A voxel-based multiscale tumor response model for simulating the radiation response of hypoxic tumors was developed. It considers viable and dead tumor cells, capillary and normal cells, as well as the most relevant biological processes such as (i) proliferation of tumor cells, (ii) hypoxia-induced angiogenesis, (iii) spatial exchange of cells leading to tumor growth, (iv) oxygen-dependent cell survival after irradiation, (v) resorption of dead cells, and (vi) spatial exchange of cells leading to tumor shrinkage. Oxygenation is described on a microscopic scale using a previously published tumor oxygenation model, which calculates the oxygen distribution for each voxel using the vascular fraction as the most important input parameter. To demonstrate the capabilities of the model, the dependence of the oxygen distribution on tumor growth and radiation-induced shrinkage is investigated. In addition, the impact of three different reoxygenation processes is compared and tumor control probability (TCP) curves for a squamous cells carcinoma of the head and neck (HNSSC) are simulated under normoxic and hypoxic conditions. The model describes the spatiotemporal behavior of the tumor on three different scales: (i) on the macroscopic scale, it describes tumor growth and shrinkage during radiation treatment, (ii) on a mesoscopic scale, it provides the cell density and vascular fraction for each voxel, and (iii) on the microscopic scale, the oxygen distribution may be obtained in terms of oxygen histograms. With increasing tumor size, the simulated tumors develop a hypoxic core. Within the model, tumor shrinkage was

  19. A voxel-based multiscale model to simulate the radiation response of hypoxic tumors

    Espinoza, I.; Peschke, P.; Karger, C. P.

    2015-01-01

    Purpose: In radiotherapy, it is important to predict the response of tumors to irradiation prior to the treatment. This is especially important for hypoxic tumors, which are known to be highly radioresistant. Mathematical modeling based on the dose distribution, biological parameters, and medical images may help to improve this prediction and to optimize the treatment plan. Methods: A voxel-based multiscale tumor response model for simulating the radiation response of hypoxic tumors was developed. It considers viable and dead tumor cells, capillary and normal cells, as well as the most relevant biological processes such as (i) proliferation of tumor cells, (ii) hypoxia-induced angiogenesis, (iii) spatial exchange of cells leading to tumor growth, (iv) oxygen-dependent cell survival after irradiation, (v) resorption of dead cells, and (vi) spatial exchange of cells leading to tumor shrinkage. Oxygenation is described on a microscopic scale using a previously published tumor oxygenation model, which calculates the oxygen distribution for each voxel using the vascular fraction as the most important input parameter. To demonstrate the capabilities of the model, the dependence of the oxygen distribution on tumor growth and radiation-induced shrinkage is investigated. In addition, the impact of three different reoxygenation processes is compared and tumor control probability (TCP) curves for a squamous cells carcinoma of the head and neck (HNSSC) are simulated under normoxic and hypoxic conditions. Results: The model describes the spatiotemporal behavior of the tumor on three different scales: (i) on the macroscopic scale, it describes tumor growth and shrinkage during radiation treatment, (ii) on a mesoscopic scale, it provides the cell density and vascular fraction for each voxel, and (iii) on the microscopic scale, the oxygen distribution may be obtained in terms of oxygen histograms. With increasing tumor size, the simulated tumors develop a hypoxic core. Within the

  20. Microdefects in an as-grown Czochralski silicon crystal studied by synchrotron radiation section topography with aid of computer simulation

    Iida, Satoshi; Aoki, Yoshirou; Okitsu, Kouhei; Sugita, Yoshimitsu; Kawata, Hiroshi; Abe, Takao

    1998-01-01

    Grown-in microdefects of a Czochralski (CZ) silicon crystal grown at a slow growth rate were studied by section topography using high energy synchrotron radiation. Images of the microdefects in the section topographs were analyzed quantitatively using computer simulation based on the Takagi-Taupin type dynamical diffraction theory of X-rays, and reproduced successfully by the simulation when the microdefects were assumed to be spherical strain centers. Sizes and positions of the microdefects were able to be determined by detailed comparison between the experiments and the computer simulations. The validity of the computer simulation in an analysis of the section topographs is discussed. (author)