Computational methods for industrial radiation measurement applications

International Nuclear Information System (INIS)

Gardner, R.P.; Guo, P.; Ao, Q.

1996-01-01

Computational methods have been used with considerable success to complement radiation measurements in solving a wide range of industrial problems. The almost exponential growth of computer capability and applications in the last few years leads to a open-quotes black boxclose quotes mentality for radiation measurement applications. If a black box is defined as any radiation measurement device that is capable of measuring the parameters of interest when a wide range of operating and sample conditions may occur, then the development of computational methods for industrial radiation measurement applications should now be focused on the black box approach and the deduction of properties of interest from the response with acceptable accuracy and reasonable efficiency. Nowadays, increasingly better understanding of radiation physical processes, more accurate and complete fundamental physical data, and more advanced modeling and software/hardware techniques have made it possible to make giant strides in that direction with new ideas implemented with computer software. The Center for Engineering Applications of Radioisotopes (CEAR) at North Carolina State University has been working on a variety of projects in the area of radiation analyzers and gauges for accomplishing this for quite some time, and they are discussed here with emphasis on current accomplishments

Efficiency and attenuation correction factors determination in gamma spectrometric assay of bulk samples using self radiation

International Nuclear Information System (INIS)

Haddad, Kh.

2009-02-01

Gamma spectrometry forms the most important and capable tool for measuring radioactive materials. Determination of the efficiency and attenuation correction factors is the most tedious problem in the gamma spectrometric assay of bulk samples. A new experimental and easy method for these correction factors determination using self radiation was proposed in this work. An experimental study of the correlation between self attenuation correction factor and sample thickness and its practical application was also introduced. The work was performed on NORM and uranyl nitrate bulk sample. The results of proposed methods agreed with those of traditional ones.(author)

OBJECT KINETIC MONTE CARLO SIMULATIONS OF RADIATION DAMAGE IN BULK TUNGSTEN

Energy Technology Data Exchange (ETDEWEB)

Nandipati, Giridhar; Setyawan, Wahyu; Heinisch, Howard L.; Roche, Kenneth J.; Kurtz, Richard J.; Wirth, Brian D.

2015-09-22

We used our recently developed lattice based OKMC code; KSOME [1] to carryout simulations of radiation damage in bulk W. We study the effect of dimensionality of self interstitial atom (SIA) diffusion i.e. 1D versus 3D on the defect accumulation during irradiation with a primary knock-on atom (PKA) energy of 100 keV at 300 K for the dose rates of 10-5 and 10-6 dpa/s. As expected 3D SIA diffusion significantly reduces damage accumulation due to increased probability of recombination events. In addition, dose rate, over the limited range examined here, appears to have no effect in both cases of SIA diffusion.

Investigation into Cloud Computing for More Robust Automated Bulk Image Geoprocessing

Science.gov (United States)

Brown, Richard B.; Smoot, James C.; Underwood, Lauren; Armstrong, C. Duane

2012-01-01

Geospatial resource assessments frequently require timely geospatial data processing that involves large multivariate remote sensing data sets. In particular, for disasters, response requires rapid access to large data volumes, substantial storage space and high performance processing capability. The processing and distribution of this data into usable information products requires a processing pipeline that can efficiently manage the required storage, computing utilities, and data handling requirements. In recent years, with the availability of cloud computing technology, cloud processing platforms have made available a powerful new computing infrastructure resource that can meet this need. To assess the utility of this resource, this project investigates cloud computing platforms for bulk, automated geoprocessing capabilities with respect to data handling and application development requirements. This presentation is of work being conducted by Applied Sciences Program Office at NASA-Stennis Space Center. A prototypical set of image manipulation and transformation processes that incorporate sample Unmanned Airborne System data were developed to create value-added products and tested for implementation on the "cloud". This project outlines the steps involved in creating and testing of open source software developed process code on a local prototype platform, and then transitioning this code with associated environment requirements into an analogous, but memory and processor enhanced cloud platform. A data processing cloud was used to store both standard digital camera panchromatic and multi-band image data, which were subsequently subjected to standard image processing functions such as NDVI (Normalized Difference Vegetation Index), NDMI (Normalized Difference Moisture Index), band stacking, reprojection, and other similar type data processes. Cloud infrastructure service providers were evaluated by taking these locally tested processing functions, and then

Electrical resistance behavior with gamma radiation dose in bulk carbon nanostrutured samples

International Nuclear Information System (INIS)

Lage, J.; Leyva, A.; Pinnera, I.; Desdin, L. F.; Abreu, Y.; Cruz, C. M.; Leyva, D.; Toledo, C.

2013-01-01

The aim of this paper is to study the effects of 60 Co gamma radiation on the electrical resistance and V-I characteristic of bulk carbon nano structured samples obtained by electric arc discharge in water method. Images of pristine samples obtained with scanning electron, and the results in graphical form of the electrical characterization of irradiated samples are presented in the text. It was observed that the electrical resistance vs. dose behavior shows an initial increment reaching the maximum at approximately 135 kGy, followed by a drop of the resistance values. These behaviors are associated with the progressive generation of radiation induced defects in the sample, whose number increases to reach saturation at 135 kGy. From this dose, defects could lead to cross-links between different nano structures present in the sample conducting to a gradually drop in electrical resistance. The measured V-I curves show that, increasing exposure to the 60 Co gamma radiation, the electrical properties of the studied samples transit from a semiconductor towards a predominantly metallic behavior. These results were compared with those obtained for a sample of graphite powder irradiated under the same conditions. (Author)

Radiation management computer system for Monju

International Nuclear Information System (INIS)

Aoyama, Kei; Yasutomo, Katsumi; Sudou, Takayuki; Yamashita, Masahiro; Hayata, Kenichi; Ueda, Hajime; Hosokawa, Hideo

2002-01-01

Radiation management of nuclear power research institutes, nuclear power stations and other such facilities are strictly managed under Japanese laws and management policies. Recently, the momentous issues of more accurate radiation dose management and increased work efficiency has been discussed. Up to now, Fuji Electric Company has supplied a large number of Radiation Management Systems to nuclear power stations and related nuclear facilities. We introduce the new radiation management computer system with adopted WWW technique for Japan Nuclear Cycle Development Institute, MONJU Fast Breeder Reactor (MONJU). (author)

Combined Bulk and Surface Radiation Damage Effects at Very High Fluences in Silicon Detectors: Measurements and TCAD Simulations

CERN Document Server

Moscatelli, F; Morozzi, A; Mendicino, R; Dalla Betta, G F; Bilei, G M

2016-01-01

In this work we propose a new combined TCAD radiation damage modelling scheme, featuring both bulk and surface radiation damage effects, for the analysis of silicon detectors aimed at the High Luminosity LHC. In particular, a surface damage model has been developed by introducing the relevant parameters (NOX, NIT) extracted from experimental measurements carried out on p-type substrate test structures after gamma irradiations at doses in the range 10-500 Mrad(Si). An extended bulk model, by considering impact ionization and deep-level cross-sections variation, was included as well. The model has been validated through the comparison of the simulation findings with experimental measurements carried out at very high fluences (2×1016 1 MeV equivalent n/cm2) thus fostering the application of this TCAD approach for the design and optimization of the new generation of silicon detectors to be used in future HEP experiments.

Concept and computation of radiation dose at high energies

International Nuclear Information System (INIS)

Sarkar, P.K.

2010-01-01

Computational dosimetry, a subdiscipline of computational physics devoted to radiation metrology, is determination of absorbed dose and other dose related quantities by numbers. Computations are done separately both for external and internal dosimetry. The methodology used in external beam dosimetry is necessarily a combination of experimental radiation dosimetry and theoretical dose computation since it is not feasible to plan any physical dose measurements from inside a living human body

Computing in radiation protection and health physics - 10 years further

International Nuclear Information System (INIS)

Behrens, R.; Greif, N.; Struwe, H.; Wissmann, F.

2008-01-01

Computing influences radiation protection and health physics more extensively as ever before. The good old data processing and main frame computing has changed towards information technology in a wider sense. Technologies and operating systems out of workplace computing have amended microprocessor technology in measuring devices. The boundaries between them are constantly in a state of flux. The use of the world wide web has become indispensable. No radiation protection expert could still manage without a workplace computer. Measuring networks, radiation protection information systems, data bases, computer simulation and other challenging applications form the image of today. (orig.)

Computational methods in several fields of radiation dosimetry

International Nuclear Information System (INIS)

Paretzke, Herwig G.

2010-01-01

Full text: Radiation dosimetry has to cope with a wide spectrum of applications and requirements in time and size. The ubiquitous presence of various radiation fields or radionuclides in the human home, working, urban or agricultural environment can lead to various dosimetric tasks starting from radioecology, retrospective and predictive dosimetry, personal dosimetry, up to measurements of radionuclide concentrations in environmental and food product and, finally in persons and their excreta. In all these fields measurements and computational models for the interpretation or understanding of observations are employed explicitly or implicitly. In this lecture some examples of own computational models will be given from the various dosimetric fields, including a) Radioecology (e.g. with the code systems based on ECOSYS, which was developed far before the Chernobyl reactor accident, and tested thoroughly afterwards), b) Internal dosimetry (improved metabolism models based on our own data), c) External dosimetry (with the new ICRU-ICRP-Voxelphantom developed by our lab), d) Radiation therapy (with GEANT IV as applied to mixed reactor radiation incident on individualized voxel phantoms), e) Some aspects of nanodosimetric track structure computations (not dealt with in the other presentation of this author). Finally, some general remarks will be made on the high explicit or implicit importance of computational models in radiation protection and other research field dealing with large systems, as well as on good scientific practices which should generally be followed when developing and applying such computational models

Fission fragment simulation of fusion neutron radiation effects on bulk mechanical properties

International Nuclear Information System (INIS)

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

Symbolic math for computation of radiation shielding

International Nuclear Information System (INIS)

Suman, Vitisha; Datta, D.; Sarkar, P.K.; Kushwaha, H.S.

2010-01-01

Radiation transport calculations for shielding studies in the field of accelerator technology often involve intensive numerical computations. Traditionally, radiation transport equation is solved using finite difference scheme or advanced finite element method with respect to specific initial and boundary conditions suitable for the geometry of the problem. All these computations need CPU intensive computer codes for accurate calculation of scalar and angular fluxes. Computation using symbols of the analytical expression representing the transport equation as objects is an enhanced numerical technique in which the computation is completely algorithm and data oriented. Algorithm on the basis of symbolic math architecture is developed using Symbolic math toolbox of MATLAB software. Present paper describes the symbolic math algorithm and its application as a case study in which shielding calculation of rectangular slab geometry is studied for a line source of specific activity. Study of application of symbolic math in this domain evolves a new paradigm compared to the existing computer code such as DORT. (author)

Using computer-based training to facilitate radiation protection review

International Nuclear Information System (INIS)

Abercrombie, J.S.; Copenhaver, E.D.

1989-01-01

In a national laboratory setting, it is necessary to provide radiation protection overview and training to diverse parts of the laboratory population. This includes employees at research reactors, accelerators, waste facilities, radiochemical isotope processing, and analytical laboratories, among others. In addition, our own radiation protection and monitoring staffs must be trained. To assist in the implementation of this full range of training, ORNL has purchased prepackaged computer-based training in health physics and technical mathematics with training modules that can be selected from many topics. By selection of specific modules, appropriate radiation protection review packages can be determined to meet many individual program needs. Because our radiation protection personnel must have some previous radiation protection experience or the equivalent of an associate's degree in radiation protection for entry level, the computer-based training will serve primarily as review of major principles. Others may need very specific prior training to make the computer-based training effective in their work situations. 4 refs

Computer applications in radiation protection

International Nuclear Information System (INIS)

Cole, P.R.; Moores, B.M.

1995-01-01

Computer applications in general and diagnostic radiology in particular are becoming more widespread. Their application to the field of radiation protection in medical imaging, including quality control initiatives, is similarly becoming more widespread. Advances in computer technology have enabled departments of diagnostic radiology to have access to powerful yet affordable personal computers. The application of databases, expert systems and computer-based learning is under way. The executive information systems for the management of dose and QA data that are under way at IRS are discussed. An important consideration in developing these pragmatic software tools has been the range of computer literacy within the end user group. Using interfaces have been specifically designed to reflect the requirements of many end users who will have little or no computer knowledge. (Author)

Systematic review on physician's knowledge about radiation doses and radiation risks of computed tomography

International Nuclear Information System (INIS)

Krille, Lucian; Hammer, Gael P.; Merzenich, Hiltrud; Zeeb, Hajo

2010-01-01

Background: The frequent use of computed tomography is a major cause of the increasing medical radiation exposure of the general population. Consequently, dose reduction and radiation protection is a topic of scientific and public concern. Aim: We evaluated the available literature on physicians' knowledge regarding radiation dosages and risks due to computed tomography. Methods: A systematic review in accordance with the Cochrane and PRISMA statements was performed using eight databases. 3091 references were found. Only primary studies assessing physicians' knowledge about computed tomography were included. Results: 14 relevant articles were identified, all focussing on dose estimations for CT. Overall, the surveys showed moderate to low knowledge among physicians concerning radiation doses and the involved health risks. However, the surveys varied considerably in conduct and quality. For some countries, more than one survey was available. There was no general trend in knowledge in any country except a slight improvement of knowledge on health risks and radiation doses in two consecutive local German surveys. Conclusions: Knowledge gaps concerning radiation doses and associated health risks among physicians are evident from published research. However, knowledge on radiation doses cannot be interpreted as reliable indicator for good medical practice.

Available computer codes and data for radiation transport analysis

International Nuclear Information System (INIS)

Trubey, D.K.; Maskewitz, B.F.; Roussin, R.W.

1975-01-01

The Radiation Shielding Information Center (RSIC), sponsored and supported by the Energy Research and Development Administration (ERDA) and the Defense Nuclear Agency (DNA), is a technical institute serving the radiation transport and shielding community. It acquires, selects, stores, retrieves, evaluates, analyzes, synthesizes, and disseminates information on shielding and ionizing radiation transport. The major activities include: (1) operating a computer-based information system and answering inquiries on radiation analysis, (2) collecting, checking out, packaging, and distributing large computer codes, and evaluated and processed data libraries. The data packages include multigroup coupled neutron-gamma-ray cross sections and kerma coefficients, other nuclear data, and radiation transport benchmark problem results

Development of Computer Program for Analysis of Irregular Non Homogenous Radiation Shielding

International Nuclear Information System (INIS)

Bang Rozali; Nina Kusumah; Hendro Tjahjono; Darlis

2003-01-01

A computer program for radiation shielding analysis has been developed to obtain radiation attenuation calculation in non-homogenous radiation shielding and irregular geometry. By determining radiation source strength, geometrical shape of radiation source, location, dimension and geometrical shape of radiation shielding, radiation level of a point at certain position from radiation source can be calculated. By using a computer program, calculation result of radiation distribution analysis can be obtained for some analytical points simultaneously. (author)

Mining the bulk positron lifetime

International Nuclear Information System (INIS)

Aourag, H.; Guittom, A.

2009-01-01

We introduce a new approach to investigate the bulk positron lifetimes of new systems based on data-mining techniques. Through data mining of bulk positron lifetimes, we demonstrate the ability to predict the positron lifetimes of new semiconductors on the basis of available semiconductor data already studied. Informatics techniques have been applied to bulk positron lifetimes for different tetrahedrally bounded semiconductors in order to discover computational design rules. (copyright 2009 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Computer simulations of supercooled polymer melts in the bulk and in confined geometry

International Nuclear Information System (INIS)

Baschnagel, J; Varnik, F

2005-01-01

We survey results of computer simulations for the structure and dynamics of supercooled polymer melts and films. Our survey is mainly concerned with features of a coarse grained polymer model-a bead-spring model-in the temperature regime above the critical glass temperature T c of the ideal mode-coupling theory (MCT). We divide our discussion into two parts: a part devoted to bulk properties and a part dealing with thin films. The discussion of the bulk properties focuses on two aspects: a comparison of the simulation results with MCT and an analysis of dynamic heterogeneities. We explain in detail how the analyses are performed and what results may be obtained, and we critically assess their strengths and weaknesses. In discussing the application of MCT we also present first results of a quantitative comparison which does not rely on fits, but exploits static input from the simulation to predict the relaxation dynamics. The second part of this review is devoted to extensions of the simulations from the bulk to thin films. We explore in detail the influence of the boundary condition, imposed by smooth or rough walls, on the structure and dynamics of the polymer melt. Geometric confinement is found to shift the glass transition temperature T g (or T c in our case) relative to the bulk. We compare our and other simulation results for the T g shift with experimental data, briefly survey some theoretical ideas for explaining these shifts and discuss related simulation work on the glass transition of confined liquids. Finally, we also present some technical details of how to perform fits to MCT and give a brief introduction to another approach to the glass transition based on the potential energy landscape of a liquid. (topical review)

A computer simulation model to compute the radiation transfer of mountainous regions

Science.gov (United States)

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.

Subthreshold radiation-induced processes in the bulk and on surfaces and interfaces of solids

International Nuclear Information System (INIS)

Itoh, N.

1998-01-01

A review is given on the processes induced under irradiation by electronic encounters and by elastic encounters below the knock-on threshold. It is pointed out that electronic encounters cause bond scission that results in defect formation and sputtering in a variety of materials. The conditions for generation of permanent radiation-induced process as a consequence of electronic encounters are critically examined. Two critical issues are localization of electronic excitation energy and energetics. Self-trapping of excitons is one way of localization; otherwise defects are involved in localization and therefore in radiation-induced processes (RIP) by electronic excitation. Arguments on energetics indicate presence of linear and nonlinear electronic process with respect to the density of excitation. The registration of energetic heavy-ion tracks is explained in terms of non-linear electronic processes. The difference in the processes in the bulk, on surfaces and at interfaces is critically discussed. The possible contribution of subthreshold elastic encounters to thermodynamically driven interface reaction is also discussed. (orig.)

Computational Investigation of Soot and Radiation in Turbulent Reacting Flows

Science.gov (United States)

Lalit, Harshad

This study delves into computational modeling of soot and infrared radiation for turbulent reacting flows, detailed understanding of both of which is paramount in the design of cleaner engines and pollution control. In the first part of the study, the concept of Stochastic Time and Space Series Analysis (STASS) as a numerical tool to compute time dependent statistics of radiation intensity is introduced for a turbulent premixed flame. In the absence of high fidelity codes for large eddy simulation or direct numerical simulation of turbulent flames, the utility of STASS for radiation imaging of reacting flows to understand the flame structure is assessed by generating images of infrared radiation in spectral bands dominated by radiation from gas phase carbon dioxide and water vapor using an assumed PDF method. The study elucidates the need for time dependent computation of radiation intensity for validation with experiments and the need for accounting for turbulence radiation interactions for correctly predicting radiation intensity and consequently the flame temperature and NOx in a reacting fluid flow. Comparison of single point statistics of infrared radiation intensity with measurements show that STASS can not only predict the flame structure but also estimate the dynamics of thermochemical scalars in the flame with reasonable accuracy. While a time series is used to generate realizations of thermochemical scalars in the first part of the study, in the second part, instantaneous realizations of resolved scale temperature, CO2 and H2O mole fractions and soot volume fractions are extracted from a large eddy simulation (LES) to carry out quantitative imaging of radiation intensity (QIRI) for a turbulent soot generating ethylene diffusion flame. A primary motivation of the study is to establish QIRI as a computational tool for validation of soot models, especially in the absence of conventional flow field and measured scalar data for sooting flames. Realizations of

Radiation hardness of silicon detectors manufactured on epitaxial material and FZ bulk enriched with oxygen, carbon, tin and platinum

CERN Document Server

Ruzin, A; Glaser, M; Lemeilleur, F; Talamonti, R; Watts, S; Zanet, A

1999-01-01

Recent results on the radiation hardness of silicon detectors fabricated on epitaxial and float zone bulk silicon enriched by various impurities, such as carbon, oxygen, tin and platinum are reported. A new methodology of measurements of electrical properties of the devices has been utilized in the experiment. It has been shown that in the case of irradiation by protons, oxygen enriched silicon has better radiation hardness than standard float zone silicon. The carbon enriched silicon detectors, on the other hand, exhibited significantly inferior radiation hardness compared to standard detectors. This study shows for the first time, a violation of the widely used normalization technique of the various particle irradiations by NIEL coefficients. The study has been carried out in the framework of the RD48 (ROSE) collaboration, which studies the radiation hardening of silicon detectors. (5 refs).

Estimation of MONIN-OBUKHOV length using richardson and bulk richardson number

International Nuclear Information System (INIS)

Essa, K.S.M.

2000-01-01

The 1996 NOVA atmospheric boundary layer data from North Carolina are used in 30 minute's averages for five days. Because of missing data of friction velocity (u) and sensible heat flux (H), it is urgent to calculate (u*)and (H) using the equations of logarithmic wind speed and net radiation (Briggs [7]), which are considered in this work. It is found that the correlation between the predicted and observed values of (u*) and (H) is 0.88 and 0.86 respectively. A comparison is made of the Monin-Obukhov length scale (L) estimated using Richardson number (R i ) and bulk Richardson number (Ri b ) with L-value computed using formula of (L), it is found that the agreement between the predicted and observed values of (L) is better in the case (L)is estimated from the bulk Richardson number (Ri b ), rather than from the gradient Richarson number(R j )

Computer-based and web-based radiation safety training

Energy Technology Data Exchange (ETDEWEB)

Owen, C., LLNL

1998-03-01

The traditional approach to delivering radiation safety training has been to provide a stand-up lecture of the topic, with the possible aid of video, and to repeat the same material periodically. New approaches to meeting training requirements are needed to address the advent of flexible work hours and telecommuting, and to better accommodate individuals learning at their own pace. Computer- based and web-based radiation safety training can provide this alternative. Computer-based and web- based training is an interactive form of learning that the student controls, resulting in enhanced and focused learning at a time most often chosen by the student.

Disinfection ultraviolet radiation bulk food products

OpenAIRE

Семенов, А. А.

2014-01-01

В работе представлены результаты обеззараживания сыпучих пищевых продуктов ультрафиолетовым излучением. Предложена технология бактерицидного обеззараживания сыпучих продуктов с размером частиц до 50 мкм. Проведены необходимые расчеты, связанные с дозой облучения, с временем пребывания частиц в зоне облучения и необходимой дозой инактивации в зависимости от вида бактерий. Considered the results of bulk food products disinfection by ultraviolet radiation. The technology bactericidal disinfec...

Radiation and pregnancy: a self-teaching computer program

International Nuclear Information System (INIS)

Kumar, Pratik; Rehani, M.M.

1994-01-01

Two self-interacting computer programs have been developed. The first program which consists of fifteen topics apprises the users with broad spectrum of radiation risks to the unborn during pregnancy and the status of various views in this regard. Another program estimates the dose to uterus in sixteen radiological examinations depending upon the radiographic parameters used. The dose to uterus and hence to the fetus calculated by computer program in different radiographic views have been found to be in agreement with that reported in NRPB-R200 survey report. The two programs combined provide a better understanding of the rather confusing situation regarding dilemma about termination of pregnancy following inadvertent radiation exposure, apprehension about radiation effect in the minds of prescribing doctor and patients, dose estimation and advice to pregnant workers and like. (author). 10 refs

Computing Radiative Transfer in a 3D Medium

Science.gov (United States)

Von Allmen, Paul; Lee, Seungwon

2012-01-01

A package of software computes the time-dependent propagation of a narrow laser beam in an arbitrary three- dimensional (3D) medium with absorption and scattering, using the transient-discrete-ordinates method and a direct integration method. Unlike prior software that utilizes a Monte Carlo method, this software enables simulation at very small signal-to-noise ratios. The ability to simulate propagation of a narrow laser beam in a 3D medium is an improvement over other discrete-ordinate software. Unlike other direct-integration software, this software is not limited to simulation of propagation of thermal radiation with broad angular spread in three dimensions or of a laser pulse with narrow angular spread in two dimensions. Uses for this software include (1) computing scattering of a pulsed laser beam on a material having given elastic scattering and absorption profiles, and (2) evaluating concepts for laser-based instruments for sensing oceanic turbulence and related measurements of oceanic mixed-layer depths. With suitable augmentation, this software could be used to compute radiative transfer in ultrasound imaging in biological tissues, radiative transfer in the upper Earth crust for oil exploration, and propagation of laser pulses in telecommunication applications.

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

International Nuclear Information System (INIS)

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

Bulk viscosity in holographic Lifshitz hydrodynamics

International Nuclear Information System (INIS)

Hoyos, Carlos; Kim, Bom Soo; Oz, Yaron

2014-01-01

We compute the bulk viscosity in holographic models dual to theories with Lifshitz scaling and/or hyperscaling violation, using a generalization of the bulk viscosity formula derived in arXiv:1103.1657 from the null focusing equation. We find that only a class of models with massive vector fields are truly Lifshitz scale invariant, and have a vanishing bulk viscosity. For other holographic models with scalars and/or massless vector fields we find a universal formula in terms of the dynamical exponent and the hyperscaling violation exponent

Device for determining the content of bulk materials on conveyor belts

International Nuclear Information System (INIS)

Fritsche, D.

1983-01-01

On the basis of the forward scattering of photon radiation the invention is aimed at determining the content of bulk material, in particular the ash content of lignite, independently of the height of the material conveyed by belts. This could be achieved by making the radiation source support movable, so that the distance between source and conveyor belt is variable and adaptable to the mean height of the bulk material

A COTS-based single board radiation-hardened computer for space applications

International Nuclear Information System (INIS)

Stewart, S.; Hillman, R.; Layton, P.; Krawzsenek, D.

1999-01-01

There is great community interest in the ability to use COTS (Commercial-Off-The-Shelf) technology in radiation environments. Space Electronics, Inc. has developed a high performance COTS-based radiation hardened computer. COTS approaches were selected for both hardware and software. Through parts testing, selection and packaging, all requirements have been met without parts or process development. Reliability, total ionizing dose and single event performance are attractive. The characteristics, performance and radiation resistance of the single board computer will be presented. (authors)

Bulk viscous Zel'dovich fluid model and its asymptotic behavior

Energy Technology Data Exchange (ETDEWEB)

Nair, K.R.; Mathew, Titus K. [Cochin University of Science and Technology, Department of Physics, Kochi (India)

2016-10-15

In this paper we consider a flat FLRW universe with bulk viscous Zel'dovich fluid as the cosmic component. Considering the bulk viscosity as characterized by a constant bulk viscous coefficient, we analyze the evolution of the Hubble parameter. Type Ia Supernovae data is used for constraining the model and for extracting the constant bulk viscous parameter and present the Hubble parameter. We also present the analysis of the scale factor, equation of state, and deceleration parameter. The model predicts the later time acceleration and is also compatible with the age of the universe as given by the oldest globular clusters. Study of the phase-space behavior of the model shows that a universe dominated by bulk viscous Zel'dovich fluid is stable. But the inclusion of a radiation component in addition to the Zel'dovich fluid makes the model unstable. Hence, even though the bulk viscous Zel'dovich fluid dominated universe is a feasible one, the model as such fails to predict a prior radiation dominated phase. (orig.)

The situation of computer utilization in radiation therapy in Japan and other countries and problems

International Nuclear Information System (INIS)

Onai, Yoshio

1981-01-01

The uses of computers in radiation therapy are various, such as radiation dose calculation, clinical history management, radiotherapeutical instrument automation and biological model. To grasp the situation in this field, a survey by questionnaire was carried out internationally at the time of the 7th International Conference on the Use of Computers in Radiation Therapy held in Kawasaki and Tokyo in September, 1980. The surveyed nations totaled 21 including Japan; the number of facilities answered were 203 in Japan and 111 in other countries, and the period concerned is December, 1979, to September, 1980. The results of the survey are described as follows: areas of use of computers in hospitals, computer utilization in radiation department, computer uses in radiation therapy, and evaluation of radiotherapeutical computer uses and problems. (J.P.N.)

The Effects Of Ultrasonic Application For The Microbiological Quality Of Bulk Cooking Oil

Directory of Open Access Journals (Sweden)

Wisnu Istanto

2015-08-01

Full Text Available Radiation is one of natural phenomenon that often discussed in light atomic reaction nuclear application and electromagnetic wave especially in gamma ray X ray and UV light. Commonly we usually think that they are negative deadly and dangerous for living creatures. Radiaton may be correlated with thermal phenomenon but this reasearch was applied to get audio phenomenon and radiation especially ultrasonic radiation. Sound is a particle of vibration that propagates through medium and transmitted as longitudinal wave in which the displacement of the medium is parallel to the propagation of the wave. Radiation is the emission of waves in all directions in space by vibratory sources transducers form small balls or knob 234 this study were irradiating exposing to bulk cooking oils. The bulk cooking oil was treated by the ultrasonic exposure 1.5 hours and 3 hours and 24-hour incubation that it showed no aerobic colony. And besides the untreated bulk cooking oil showed a few aerobic colonies. And also the untreated used bulk cooking oil showed more some aerobic colonies. The research results shows that ultrasonic exposure at 48 kHz for 1.5 hours can enhance the microbiological quality of bulk cooking oil for 10 day storage.

Radiation physics, biophysics, and radiation biology. Progress report, December 1, 1985-November 30, 1986

International Nuclear Information System (INIS)

Hall, E.J.

1986-07-01

This is the annual report of the Radiological Research Laboratory of the Department of Radiation Oncology, Columbia University. The bulk of the research of the Laboratory involves basic and fundamental aims, not confined to radiotherapy. Research carried out in the Laboratory covers the determination of microdosimetry quantities, computer simulation of particle tracks, determination of oncogenic transformation, and the transfection of DNA into cells. The Hallmark of the Laboratory is the interaction between physics and biology

Radiation levels from computer monitor screens within Benue State ...

African Journals Online (AJOL)

Investigation of possible presence of soft X-ray levels from Computer Screens at distances of 0.5m and 1.0m was carried out within Benue State University, Makurdi, using ten different monitor models. Radiation measurement was carried out using a portable digital radiation meter, INSPECTOR 06250 (SE international Inc.

European questionnaire on the use of computer programmes in radiation dosimetry

International Nuclear Information System (INIS)

Gualdrini, G.; Tanner, R.; Terrisol, M.

1999-01-01

Because of a potential reduction of necessary experimental efforts, the combination of measurements and supplementing calculations, also in the field of radiation dosimetry, may allow time and money to be saved if computational methods are used which are well suited to reproduce experimental data in a satisfactory quality. The dramatic increase in computing power in recent years now permits the use of computational tools for dosimetry also in routine applications. Many institutions dealing with radiation protection, however, have small groups which, in addition to their routine work, often cannot afford to specialise in the field of computational dosimetry. This means that not only experts but increasingly also casual users employ complicated computational tools such as general-purpose transport codes. This massive use of computer programmes in radiation protection and dosimetry applications motivated the Concerted Action Investigation and Quality Assurance of Numerical Methods in Radiation Protection Dosimetry of the 4th framework programme of the European Commission to prepare, distribute and evaluate a questionnaire on the use of such codes. A significant number of scientists from nearly all the countries of the European Community (and some countries outside Europe) contributed to the questionnaire, that allowed to obtain a satisfactory overview of the state of the art in this field. The results obtained from the questionnaire and summarised in the present Report are felt to be indicative of the situation of using sophisticated computer codes within the European Community although the group of participating scientist may not be a representative sample in a strict statistical sense [it

Computer modelling of statistical properties of SASE FEL radiation

International Nuclear Information System (INIS)

Saldin, E. L.; Schneidmiller, E. A.; Yurkov, M. V.

1997-01-01

The paper describes an approach to computer modelling of statistical properties of the radiation from self amplified spontaneous emission free electron laser (SASE FEL). The present approach allows one to calculate the following statistical properties of the SASE FEL radiation: time and spectral field correlation functions, distribution of the fluctuations of the instantaneous radiation power, distribution of the energy in the electron bunch, distribution of the radiation energy after monochromator installed at the FEL amplifier exit and the radiation spectrum. All numerical results presented in the paper have been calculated for the 70 nm SASE FEL at the TESLA Test Facility being under construction at DESY

Radiation Tolerant, FPGA-based SmallSat Computer System

Data.gov (United States)

National Aeronautics and Space Administration — The goal of this project is to mature the technology readiness of a radiation tolerant smallsat computer system for a subsequent orbital flight demonstration. The...

Silicene-terminated surface of calcium and strontium disilicides: properties and comparison with bulk structures by computational methods

Science.gov (United States)

Brázda, Petr; Mutombo, Pingo; Ondráček, Martin; Corrêa, Cinthia Antunes; Kopeček, Jaromír; Palatinus, Lukáš

2018-05-01

The bulk and surface structures of calcium and strontium disilicides are investigated by computational methods using density functional theory. The investigated structures are R6, R3 and P1-CaSi2 and P1-SrSi2. The investigated properties are the cleavage energy at the silicene sheet, buckling of the bulk and surface silicene layers, charge transfer from calcium to silicon, band structure of bulk and surface-terminated structures and adsorption energies on H atoms and H2 molecules on the silicene-terminated surface of the R3 phase. The cleavage energy at the silicene surface is low in all cases. Structures P1-CaSi2 and R3-CaSi2 contain silicene sheets with different coordination to Ca, while R6-CaSi2 contains both types of the sheets. It is shown that the properties of the two types of silicene-like sheets in R6-CaSi2 are similar to those of the corresponding sheets in P1-CaSi2 and R3-CaSi2, and the thermodynamically stable R6 phase is a good candidate for experimental investigation of silicene-terminated surface in calcium disilicide.

Bulk viscosity in 2SC quark matter

International Nuclear Information System (INIS)

Alford, Mark G; Schmitt, Andreas

2007-01-01

The bulk viscosity of three-flavour colour-superconducting quark matter originating from the nonleptonic process u + s ↔ u + d is computed. It is assumed that up and down quarks form Cooper pairs while the strange quark remains unpaired (2SC phase). A general derivation of the rate of strangeness production is presented, involving contributions from a multitude of different subprocesses, including subprocesses that involve different numbers of gapped quarks as well as creation and annihilation of particles in the condensate. The rate is then used to compute the bulk viscosity as a function of the temperature, for an external oscillation frequency typical of a compact star r-mode. We find that, for temperatures far below the critical temperature T c for 2SC pairing, the bulk viscosity of colour-superconducting quark matter is suppressed relative to that of unpaired quark matter, but for T ∼> T c /30 the colour-superconducting quark matter has a higher bulk viscosity. This is potentially relevant for the suppression of r-mode instabilities early in the life of a compact star

Augmented therapy of extensive Hodgkin's disease: radiation to bulk disease or prolongation of induction chemotherapy did not improve survival

International Nuclear Information System (INIS)

Rafla, S.; Coleman, M.; Propert, K.; Glicksman, A.; Peterson, B.; Nissen, N.; Brunner, K.; Kaufmann, T.; Holland, J.; Anderson, J.; Gottlieb, A.

1996-01-01

Purpose: This prospective, randomized trial in extensive, untreated Hodgkin's disease was undertaken to assess the potential benefit of augmented therapy (12 months chemotherapy or radiation to 'bulk' disease) compared to standard, six months chemotherapy. Materials and Methods: Two-hundred fifty-eight patients, mostly stage IV, were randomized to four treatment regimens consisting of 6 cycles of CCNU, vinblastine, procarbazine, and prednisone (CVPP); 12 cycles of CVPP; 6 cycles of CVPP followed by 25 Gray (Gy) radiotherapy; or 3 cycles CVPP, 25 Gy radiotherapy, and 3 cycles CVPP. Results: Complete remissions were achieved in 65% of all patients. A 58% overall 5 year survival was obtained. Relapses in irradiated areas of bulk disease occurred in only 6% of responding patients. There was, however, no statistical difference in response frequency, disease free survival or overall survival amongst the four regimens. Elderly patients responded less frequently. Conclusion: While radiotherapy provided control of local (bulk) disease, no impact on overall survival was apparent. Likewise doubling the duration of chemotherapy did not improve response or survival. Augmentation of therapy with either radiotherapy or more chemotherapy in this study was of no benefit when compared to the standard six months of treatment

Computational anthropomorphic phantoms for radiation protection dosimetry: evolution and prospects

International Nuclear Information System (INIS)

Lee, Choonsik; Lee, Jaiki

2006-01-01

Computational anthropomorphic phantoms are computer models of human anatomy used in the calculation of radiation dose distribution in the human body upon exposure to a radiation source. Depending on the manner to represent human anatomy, they are categorized into two classes: stylized and tomographic phantoms. Stylized phantoms, which have mainly been developed at the Oak Ridge National Laboratory (ORNL), describe human anatomy by using simple mathematical equations of analytical geometry. Several improved stylized phantoms such as male and female adults, pediatric series, and enhanced organ models have been developed following the first hermaphrodite adult stylized phantom, Medical Internal Radiation Dose (MIRD)-5 phantom. Although stylized phantoms have significantly contributed to dosimetry calculation, they provide only approximations of the true anatomical features of the human body and the resulting organ dose distribution. An alternative class of computational phantom, the tomographic phantom, is based upon three-dimensional imaging techniques such as Magnetic Resonance (MR) imaging and Computed Tomography (CT). The tomographic phantoms represent the human anatomy with a large number of voxels that are assigned tissue type and organ identity. To date, a total of around 30 tomographic phantoms including male and female adults, pediatric phantoms, and even a pregnant female, have been developed and utilized for realistic radiation dosimetry calculation. They are based on MRI/CT images or sectional color photos from patients, volunteers or cadavers. Several investigators have compared tomographic phantoms with stylized phantoms, and demonstrated the superiority of tomographic phantoms in terms of realistic anatomy and dosimetry calculation. This paper summarizes the history and current status of both stylized and tomographic phantoms, including Korean computational phantoms. Advantages, limitations, and future prospects are also discussed

Project Management of a personnel radiation records computer system

International Nuclear Information System (INIS)

Labenski, T.

1984-01-01

Project Management techniques have been used to develop a data base management information system to provide storage and retrieval of personnel radiation and Health Physics records. The system is currently being developed on a Hewlett Packard 1000 Series E Computer with provisions to include plant radiation survey information, radiation work permit information, inventory management for Health Physics supplies and instrumentation, and control of personnel access to radiological controlled areas. The methodologies used to manage the overall project are presented along with selection and management of software vendors

Microcomputers, desk calculators and process computers for use in radiation protection

International Nuclear Information System (INIS)

Burgkhardt, B.; Nolte, G.; Schollmeier, W.; Rau, G.

1983-01-01

The goals achievable, or to be pursued, in radiation protection measurement and evaluation by using computers are explained. As there is a large variety of computers available offering a likewise large variety, of performances, use of a computer is justified even for minor measuring and evaluation tasks. The subdivision into: Microcomputers as an installed part of measuring equipment; measuring and evaluation systems with desk calculators; measuring and evaluation systems with process computers is done to explain the importance and extent of the measuring or evaluation tasks and the computing devices suitable for the various purposes. The special requirements to be met in order to fulfill the different tasks are discussed, both in terms of hardware and software and in terms of skill and knowledge of the personnel, and are illustrated by an example showing the usefulness of computers in radiation protection. (orig./HP) [de

Errors in measuring absorbed radiation and computing crop radiation use efficiency

International Nuclear Information System (INIS)

Gallo, K.P.; Daughtry, C.S.T.; Wiegand, C.L.

1993-01-01

Radiation use efficiency (RUE) is often a crucial component of crop growth models that relate dry matter production to energy received by the crop. RUE is a ratio that has units g J -1 , if defined as phytomass per unit of energy received, and units J J -1 , if defined as the energy content of phytomass per unit of energy received. Both the numerator and denominator in computation of RUE can vary with experimental assumptions and methodologies. The objectives of this study were to examine the effect that different methods of measuring the numerator and denominator have on the RUE of corn (Zea mays L.) and to illustrate this variation with experimental data. Computational methods examined included (i) direct measurements of the fraction of photosynthetically active radiation absorbed (f A ), (ii) estimates of f A derived from leaf area index (LAI), and (iii) estimates of f A derived from spectral vegetation indices. Direct measurements of absorbed PAR from planting to physiological maturity of corn were consistently greater than the indirect estimates based on green LAI or the spectral vegetation indices. Consequently, the RUE calculated using directly measured absorbed PAR was lower than the RUE calculated using the indirect measures of absorbed PAR. For crops that contain senesced vegetation, green LAI and the spectral vegetation indices provide appropriate estimates of the fraction of PAR absorbed by a crop canopy and, thus, accurate estimates of crop radiation use efficiency

Accurate and efficient computation of synchrotron radiation functions

International Nuclear Information System (INIS)

MacLeod, Allan J.

2000-01-01

We consider the computation of three functions which appear in the theory of synchrotron radiation. These are F(x)=x∫x∞K 5/3 (y) dy))F p (x)=xK 2/3 (x) and G p (x)=x 1/3 K 1/3 (x), where K ν denotes a modified Bessel function. Chebyshev series coefficients are given which enable the functions to be computed with an accuracy of up to 15 sig. figures

Automatic data acquisition system of environmental radiation monitor with a personal computer

International Nuclear Information System (INIS)

Ohkubo, Tohru; Nakamura, Takashi.

1984-05-01

The automatic data acquisition system of environmental radiation monitor was developed in a low price by using a PET personal computer. The count pulses from eight monitors settled at four site boundaries were transmitted to a radiation control room by a signal transmission device and analyzed by the computer via 12 channel scaler and PET-CAMAC Interface for graphic display and printing. (author)

Radiation Shielding Information Center: a source of computer codes and data for fusion neutronics studies

International Nuclear Information System (INIS)

McGill, B.L.; Roussin, R.W.; Trubey, D.K.; Maskewitz, B.F.

1980-01-01

The Radiation Shielding Information Center (RSIC), established in 1962 to collect, package, analyze, and disseminate information, computer codes, and data in the area of radiation transport related to fission, is now being utilized to support fusion neutronics technology. The major activities include: (1) answering technical inquiries on radiation transport problems, (2) collecting, packaging, testing, and disseminating computing technology and data libraries, and (3) reviewing literature and operating a computer-based information retrieval system containing material pertinent to radiation transport analysis. The computer codes emphasize methods for solving the Boltzmann equation such as the discrete ordinates and Monte Carlo techniques, both of which are widely used in fusion neutronics. The data packages include multigroup coupled neutron-gamma-ray cross sections and kerma coefficients, other nuclear data, and radiation transport benchmark problem results

Computational radiation chemistry: the emergence of a new field

International Nuclear Information System (INIS)

Bartczak, W.M.; Kroh, J.

1991-01-01

The role of the computer experiment as an information source, which is complementary to the ''real'' experiment in radiation chemistry, is discussed. The discussion is followed by a brief review of some of the simulation techniques, which have been recently applied to the problems of radiation chemistry: ion recombination in spurs and tracks of ionization, electron tunnelling in low-temperature glasses, electron localization in disordered media. (author)

The use of symbolic computation in radiative, energy, and neutron transport calculations

Science.gov (United States)

Frankel, J. I.

This investigation uses symbolic computation in developing analytical methods and general computational strategies for solving both linear and nonlinear, regular and singular, integral and integro-differential equations which appear in radiative and combined mode energy transport. This technical report summarizes the research conducted during the first nine months of the present investigation. The use of Chebyshev polynomials augmented with symbolic computation has clearly been demonstrated in problems involving radiative (or neutron) transport, and mixed-mode energy transport. Theoretical issues related to convergence, errors, and accuracy have also been pursued. Three manuscripts have resulted from the funded research. These manuscripts have been submitted to archival journals. At the present time, an investigation involving a conductive and radiative medium is underway. The mathematical formulation leads to a system of nonlinear, weakly-singular integral equations involving the unknown temperature and various Legendre moments of the radiative intensity in a participating medium. Some preliminary results are presented illustrating the direction of the proposed research.

A high energy microscope for local strain measurements within bulk materials

DEFF Research Database (Denmark)

Lienert, U.; Poulsen, H.F.; Martins, R.V.

2000-01-01

A novel diffraction technique for local, three dimensional strain scanning within bulk materials is presented. The technique utilizes high energy, micro-focussed synchrotron radiation which can penetrate several millimeters into typical metals. The spatial resolution can be as narrow as 1 mum...... in one dimension and in three dimensions about 5x10x100 mum(3) Bulk properties are probed non-destructively and in-situ measurements during thermo-mechanical processing are feasible. A dedicated experimental station has been constructed at the ID11 beamline of the European Synchrotron Radiation Facility...

3-D heat transfer computer calculations of the performance of the IAEA's air-bath calorimeters

International Nuclear Information System (INIS)

Elias, E.; Kaizermann, S.; Perry, R.B.; Fiarman, S.

1989-01-01

A three dimensional (3-D) heat transfer computer code was developed to study and optimize the design parameters and to better understand the performance characteristics of the IAEA's air-bath calorimeters. The computer model accounts for heat conduction and radiation in the complex materials of the calorimeter and for heat convection and radiation at its outer surface. The temperature servo controller is modelled as an integral part of the heat balance equations in the system. The model predictions will be validated against test data using the ANL bulk calorimeter. 11 refs., 6 figs

CT dosimetry computer codes: Their influence on radiation dose estimates and the necessity for their revision under new ICRP radiation protection standards

International Nuclear Information System (INIS)

Kim, K. P.; Lee, J.; Bolch, W. E.

2011-01-01

Computed tomography (CT) dosimetry computer codes have been most commonly used due to their user friendliness, but with little consideration for potential uncertainty in estimated organ dose and their underlying limitations. Generally, radiation doses calculated with different CT dosimetry computer codes were comparable, although relatively large differences were observed for some specific organs or tissues. The largest difference in radiation doses calculated using different computer codes was observed for Siemens Sensation CT scanners. Radiation doses varied with patient age and sex. Younger patients and adult females receive a higher radiation dose in general than adult males for the same CT technique factors. There are a number of limitations of current CT dosimetry computer codes. These include unrealistic modelling of the human anatomy, a limited number of organs and tissues for dose calculation, inability to alter patient height and weight, and non-applicability to new CT technologies. Therefore, further studies are needed to overcome these limitations and to improve CT dosimetry. (authors)

Radiation Detection Computational Benchmark Scenarios

Energy Technology Data Exchange (ETDEWEB)

Shaver, Mark W.; Casella, Andrew M.; Wittman, Richard S.; McDonald, Ben S.

2013-09-24

Modeling forms an important component of radiation detection development, allowing for testing of new detector designs, evaluation of existing equipment against a wide variety of potential threat sources, and assessing operation performance of radiation detection systems. This can, however, result in large and complex scenarios which are time consuming to model. A variety of approaches to radiation transport modeling exist with complementary strengths and weaknesses for different problems. This variety of approaches, and the development of promising new tools (such as ORNL’s ADVANTG) which combine benefits of multiple approaches, illustrates the need for a means of evaluating or comparing different techniques for radiation detection problems. This report presents a set of 9 benchmark problems for comparing different types of radiation transport calculations, identifying appropriate tools for classes of problems, and testing and guiding the development of new methods. The benchmarks were drawn primarily from existing or previous calculations with a preference for scenarios which include experimental data, or otherwise have results with a high level of confidence, are non-sensitive, and represent problem sets of interest to NA-22. From a technical perspective, the benchmarks were chosen to span a range of difficulty and to include gamma transport, neutron transport, or both and represent different important physical processes and a range of sensitivity to angular or energy fidelity. Following benchmark identification, existing information about geometry, measurements, and previous calculations were assembled. Monte Carlo results (MCNP decks) were reviewed or created and re-run in order to attain accurate computational times and to verify agreement with experimental data, when present. Benchmark information was then conveyed to ORNL in order to guide testing and development of hybrid calculations. The results of those ADVANTG calculations were then sent to PNNL for

Computer models for optimizing radiation therapy

International Nuclear Information System (INIS)

Duechting, W.

1998-01-01

The aim of this contribution is to outline how methods of system analysis, control therapy and modelling can be applied to simulate normal and malignant cell growth and to optimize cancer treatment as for instance radiation therapy. Based on biological observations and cell kinetic data, several types of models have been developed describing the growth of tumor spheroids and the cell renewal of normal tissue. The irradiation model is represented by the so-called linear-quadratic model describing the survival fraction as a function of the dose. Based thereon, numerous simulation runs for different treatment schemes can be performed. Thus, it is possible to study the radiation effect on tumor and normal tissue separately. Finally, this method enables a computer-assisted recommendation for an optimal patient-specific treatment schedule prior to clinical therapy. (orig.) [de

Custom high-reliability radiation-hard CMOS-LSI circuit design

International Nuclear Information System (INIS)

Barnard, W.J.

1981-01-01

Sandia has developed a custom CMOS-LSI design capability to provide high reliability radiation-hardened circuits. This capability relies on (1) proven design practices to enhance reliability, (2) use of well characterized cells and logic modules, (3) computer-aided design tools to reduce design time and errors and to standardize design definition, and (4) close working relationships with the system designer and technology fabrication personnel. Trade-offs are made during the design between circuit complexity/performance and technology/producibility for high reliability and radiation-hardened designs to result. Sandia has developed and is maintaining a radiation-hardened bulk CMOS technology fabrication line for production of prototype and small production volume parts

Effect of supply voltage and body-biasing on single-event transient pulse quenching in bulk fin field-effect-transistor process

International Nuclear Information System (INIS)

Yu Jun-Ting; Chen Shu-Ming; Chen Jian-Jun; Huang Peng-Cheng; Song Rui-Qiang

2016-01-01

Charge sharing is becoming an important topic as the feature size scales down in fin field-effect-transistor (FinFET) technology. However, the studies of charge sharing induced single-event transient (SET) pulse quenching with bulk FinFET are reported seldomly. Using three-dimensional technology computer aided design (3DTCAD) mixed-mode simulations, the effects of supply voltage and body-biasing on SET pulse quenching are investigated for the first time in bulk FinFET process. Research results indicate that due to an enhanced charge sharing effect, the propagating SET pulse width decreases with reducing supply voltage. Moreover, compared with reverse body-biasing (RBB), the circuit with forward body-biasing (FBB) is vulnerable to charge sharing and can effectively mitigate the propagating SET pulse width up to 53% at least. This can provide guidance for radiation-hardened bulk FinFET technology especially in low power and high performance applications. (paper)

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

International Nuclear Information System (INIS)

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

Bulk viscous matter-dominated Universes: asymptotic properties

Energy Technology Data Exchange (ETDEWEB)

Avelino, Arturo [Departamento de Física, Campus León, Universidad de Guanajuato, León, Guanajuato (Mexico); García-Salcedo, Ricardo [Centro de Investigacion en Ciencia Aplicada y Tecnologia Avanzada - Legaria del IPN, México D.F. (Mexico); Gonzalez, Tame [Departamento de Ingeniería Civil, División de Ingeniería, Universidad de Guanajuato, Guanajuato (Mexico); Nucamendi, Ulises [Instituto de Física y Matemáticas, Universidad Michoacana de San Nicolás de Hidalgo, Edificio C-3, Ciudad Universitaria, CP. 58040 Morelia, Michoacán (Mexico); Quiros, Israel, E-mail: avelino@fisica.ugto.mx, E-mail: rigarcias@ipn.mx, E-mail: tamegc72@gmail.com, E-mail: ulises@ifm.umich.mx, E-mail: iquiros6403@gmail.com [Departamento de Matemáticas, Centro Universitario de Ciencias Exactas e Ingenierías (CUCEI), Corregidora 500 S.R., Universidad de Guadalajara, 44420 Guadalajara, Jalisco (Mexico)

2013-08-01

By means of a combined use of the type Ia supernovae and H(z) data tests, together with the study of the asymptotic properties in the equivalent phase space — through the use of the dynamical systems tools — we demonstrate that the bulk viscous matter-dominated scenario is not a good model to explain the accepted cosmological paradigm, at least, under the parametrization of bulk viscosity considered in this paper. The main objection against such scenarios is the absence of conventional radiation and matter-dominated critical points in the phase space of the model. This entails that radiation and matter dominance are not generic solutions of the cosmological equations, so that these stages can be implemented only by means of unique and very specific initial conditions, i. e., of very unstable particular solutions. Such a behavior is in marked contradiction with the accepted cosmological paradigm which requires of an earlier stage dominated by relativistic species, followed by a period of conventional non-relativistic matter domination, during which the cosmic structure we see was formed. Also, we found that the bulk viscosity is positive just until very late times in the cosmic evolution, around z < 1. For earlier epochs it is negative, been in tension with the local second law of thermodynamics.

Role of electrode metallization in the performance of bulk semi-insulating InP radiation detectors

International Nuclear Information System (INIS)

Zatko, B.; Dubecky, F.; Prochazkova, O.; Necas, V.

2007-01-01

This work deals with the study of three different electrode metallizations with the aim to form a Schottky barrier contact. Electrode geometry corresponds to the requirements of digital radiography systems. As substrates bulk Liquid Encapsulated Czochralski (LEC) SI InP wafers doped with Fe and Fe+Zn are used. Results of this study show that no one of the used metallization performs as a blocking contact. However, detectors with Ti/Pt/Au metallization attained a relatively good energy resolution of 7.0 keV in full-width at half-maximum (FWHM) and the charge collection efficiency (CCE) higher than 83% for 122 keV γ-photons at 255 K. The development of SI InP radiation detectors and in particular their electrode technology is discussed in the light of observed results

Radiation shielding properties of barite coated fabric by computer programme

Energy Technology Data Exchange (ETDEWEB)

Akarslan, F.; Molla, T. [Suleyman Demirel University, Engineering Fac. Textile Dep., Isparta (Turkey); Üncü, I. S. [Suleyman Demirel University, Technological Fac. Electrical-Electronic Eng. Dep., Isparta (Turkey); Kılıncarslan, S., E-mail: seref@tef.sdu.edu.tr [Suleyman Demirel University, Engineering Fac. Civil Eng. Dep., Isparta (Turkey); Akkurt, I. [Suleyman Demirel University, Art and Science Fac., Physics Dep., Isparta (Turkey)

2015-03-30

With the development of technology radiation started to be used in variety of different fields. As the radiation is hazardous for human health, it is important to keep radiation dose as low as possible. This is done mainly using shielding materials. Barite is one of the important materials in this purpose. As the barite is not used directly it can be used in some other materials such as fabric. For this purposes barite has been coated on fabric in order to improve radiation shielding properties of fabric. Determination of radiation shielding properties of coated fabric has been done by using computer program written C# language. With this program the images obtained from digital Rontgen films is used to determine radiation shielding properties in terms of image processing numerical values. Those values define radiation shielding and in this way the coated barite effect on radiation shielding properties of fabric has been obtained.

Health promotion and computer science in radiation protection

International Nuclear Information System (INIS)

Pennarola, R.; Porzio, G.; Pennarola, E.; Cavaliere, L.

2008-01-01

An automatic system of clinical-diagnostic information aimed at radiological protection and sanitary prevention has been applied to workers exposed to ionising radiation at the University of Naples Federico II over the last 5 years. The medical surveillance has been carried out in 247 workers on duty at 29 scientific Departments and 30 laboratories of Naples University Federico II exposed to radiation sources which were constituted by a particle accelerator, Rx Diffractometer, electronic microscope and radionuclides of low energy ( 32 P, 35 S, 7 Be, 3 H, 125 I, 14 P, 14 C, 33 Y, 241 Am, 55 Fe, 109 Cd, 57 Co, 88 Y, 226 Rn, 133 Ba, 137 Cs, 60 Co, 210 Pb, 109 Cd, 22 Na). For every person exposed a computerized case sheet was elaborated recording clinical, biological, dosimetric and other preventive data (anlage, smoking, alcohol, drugs, toxics). In case of localized radiation risk, computerized capillaroscopic monitoring of the regions of the skin exposed to radiation was carried out. The results of the research show that the absorbed doses in the workers have generally been under effective dose limit for public exposure (1 mSv/y). The clinical and biological data have shown the healthiness of the workers exposed to ionising radiation. Also the capillaroscopic examinations in the localized expositions of the skin have generally given good perfusion of the exposed tissues, integrating the health concept. The statistical and computer method with computer developed graphics has proved useful in particular risk conditions (i.e. hematic alterations, functions of the emunctory organs, etc.).This research has highlighted the role of medical surveillance in developing health promotion criteria and intervention planning through a complete real-time control of data. (author)

Computer simulations of radiation damage in protein crystals

International Nuclear Information System (INIS)

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.)

The use of computer in the biological dosimetry of radiation injury with lymphocyte micronucleus

International Nuclear Information System (INIS)

Jiang Benrong; Yao Buo

1994-01-01

A new approach for determining by computer the radiation dosage in early diagnosis of radiation injury was presented, with a purpose to widen its practical application. A set of programs designed in Clanguage for computing and drawing was compiled. The technical details discussed here can be used for compiling other kinds of practical programs. It is a valuable attempt in improving the efficiency of the computer-aid clinical diagnosis

MQRAD, a computer code for synchrotron radiation from quadrupole magnets

International Nuclear Information System (INIS)

Morimoto, Teruhisa.

1984-01-01

The computer code, MQRAD, is developed for the calculation of the synchrotron radiation from the particles passing through quadrupole magnets at the straight section of the electron-positron colliding machine. This code computes the distributions of photon numbers and photon energies at any given points on the beam orbit. In this code, elements such as the quadrupole magnets and the drift spaces can be divided into many sub-elements in order to obtain the results with good accuracy. The synchrotron radiation produced by inserted quadrupole magnets at the interaction region of the electron-positron collider is one of the main background sources to the detector. The masking system against the synchrotron radiation at TRISTAN is very important because of the relatively high beam energy and the long straight section, which are 30 GeV and 100 meters, respectively. MQRAD has been used to design the masking system of the TOPAZ detector and the result is presented here as an example. (author)

Radiation interlocks - The choice between conventional hard-wired logic and computer-based systems

International Nuclear Information System (INIS)

Crook, K.F.

1987-01-01

During the past few years, the use of computers in radiation safety systems has become more widespread. This is not surprising given the ubiquitous nature of computers in the modern technological world. But is a computer a good choice for the central logic element of a personnel safety system? Recent accidents at computer controlled medical accelerators would indicate that extreme care must be exercised if malfunctions are to be avoided. The Department of Energy (DOE) has recently established a sub-committee to formulate recommendations on the use of computers in safety systems for accelerators. This paper reviews the status of the committee's recommendations, and describes radiation protection interlock systems as applied to both accelerators and to irradiation facilities. Comparisons are made between the conventional (relay) approach and designs using computers

Radiation interlocks: The choice between conventional hard-wired logic and computer-based systems

International Nuclear Information System (INIS)

Crook, K.F.

1986-11-01

During the past few years, the use of computers in radiation safety systems has become more widespread. This is not surprising given the ubiquitous nature of computers in the modern technological world. But is a computer a good choice for the central logic element of a personnel safety system. Recent accidents at computer controlled medical accelerators would indicate that extreme care must be exercised if malfunctions are to be avoided. The Department of Energy has recently established a sub-committee to formulate recommendations on the use of computers in safety systems for accelerators. This paper will review the status of the committee's recommendations, and describe radiation protection interlock systems as applied to both accelerators and to irradiation facilities. Comparisons are made between the conventional relay approach and designs using computers. 6 refs., 6 figs

Investigations into radiation damages of reactor materials by computer simulation

International Nuclear Information System (INIS)

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

Er:YAG and CTH:YAG laser radiation: contact versus non-contact enamel ablation and sonic-activated bulk composite placement

International Nuclear Information System (INIS)

Buckova, M; Kasparova, M; Dostalova, T; Jelinkova, H; Sulc, J; Nemec, M; Fibrich, M; Bradna, P; Miyagi, M

2013-01-01

Laser radiation can be used for effective caries removal and cavity preparation without significant thermal effects, collateral damage of tooth structure, or patient discomfort. The aim of this study was to compare the quality of tissue after contact or non-contact Er:YAG and CTH:YAG laser radiation ablation. The second goal was to increase the sealing ability of hard dental tissues using sonic-activated bulk filling material with change in viscosity during processing. The artificial caries was prepared in intact teeth to simulate a demineralized surface and then the Er:YAG or CTH:YAG laser radiation was applied. The enamel artificial caries was gently removed by the laser radiation and sonic-activated composite fillings were inserted. A stereomicroscope and then a scanning electron microscope were used to evaluate the enamel surface. Er:YAG contact mode ablation in enamel was quick and precise; the cavity was smooth with a keyhole shaped prism and rod relief arrangement without a smear layer. The sonic-activated filling material was consistently regularly distributed; no cracks or microleakage in the enamel were observed. CTH:YAG irradiation was able to clean but not ablate the enamel surface; in contact and also in non-contact mode there was evidence of melting and fusing of the enamel. (paper)

Er:YAG and CTH:YAG laser radiation: contact versus non-contact enamel ablation and sonic-activated bulk composite placement

Science.gov (United States)

Buckova, M.; Kasparova, M.; Dostalova, T.; Jelinkova, H.; Sulc, J.; Nemec, M.; Fibrich, M.; Bradna, P.; Miyagi, M.

2013-05-01

Laser radiation can be used for effective caries removal and cavity preparation without significant thermal effects, collateral damage of tooth structure, or patient discomfort. The aim of this study was to compare the quality of tissue after contact or non-contact Er:YAG and CTH:YAG laser radiation ablation. The second goal was to increase the sealing ability of hard dental tissues using sonic-activated bulk filling material with change in viscosity during processing. The artificial caries was prepared in intact teeth to simulate a demineralized surface and then the Er:YAG or CTH:YAG laser radiation was applied. The enamel artificial caries was gently removed by the laser radiation and sonic-activated composite fillings were inserted. A stereomicroscope and then a scanning electron microscope were used to evaluate the enamel surface. Er:YAG contact mode ablation in enamel was quick and precise; the cavity was smooth with a keyhole shaped prism and rod relief arrangement without a smear layer. The sonic-activated filling material was consistently regularly distributed; no cracks or microleakage in the enamel were observed. CTH:YAG irradiation was able to clean but not ablate the enamel surface; in contact and also in non-contact mode there was evidence of melting and fusing of the enamel.

Bulk velocity extraction for nano-scale Newtonian flows

Energy Technology Data Exchange (ETDEWEB)

Zhang, Wenfei, E-mail: zwenfei@gmail.com [Key Laboratory of Mechanical Reliability for Heavy Equipments and Large Structures of Hebei Province, Yanshan University, Qinhuangdao 066004 (China); Sun, Hongyu [Key Laboratory of Mechanical Reliability for Heavy Equipments and Large Structures of Hebei Province, Yanshan University, Qinhuangdao 066004 (China)

2012-04-16

The conventional velocity extraction algorithm in MDS method has difficulty to determine the small flow velocity. This study proposes a new method to calculate the bulk velocity in nano-flows. Based on the Newton's law of viscosity, according to the calculated viscosities and shear stresses, the flow velocity can be obtained by numerical integration. This new method can overcome the difficulty existed in the conventional MDS method and improve the stability of the computational process. Numerical results show that this method is effective for the extraction of bulk velocity, no matter the bulk velocity is large or small. -- Highlights: ► Proposed a new method to calculate the bulk velocity in nano-flows. ► It is effective for the extraction of small bulk velocity. ► The accuracy, convergence and stability of the new method is good.

Bulk velocity extraction for nano-scale Newtonian flows

International Nuclear Information System (INIS)

Zhang, Wenfei; Sun, Hongyu

2012-01-01

The conventional velocity extraction algorithm in MDS method has difficulty to determine the small flow velocity. This study proposes a new method to calculate the bulk velocity in nano-flows. Based on the Newton's law of viscosity, according to the calculated viscosities and shear stresses, the flow velocity can be obtained by numerical integration. This new method can overcome the difficulty existed in the conventional MDS method and improve the stability of the computational process. Numerical results show that this method is effective for the extraction of bulk velocity, no matter the bulk velocity is large or small. -- Highlights: ► Proposed a new method to calculate the bulk velocity in nano-flows. ► It is effective for the extraction of small bulk velocity. ► The accuracy, convergence and stability of the new method is good.

Bulk and brane decay of a (4+n)-dimensional Schwarzschild-de Sitter black hole: Scalar radiation

International Nuclear Information System (INIS)

Kanti, P.; Grain, J.; Barrau, A.

2005-01-01

In this paper, we extend the idea that the spectrum of Hawking radiation can reveal valuable information on a number of parameters that characterize a particular black hole background--such as the dimensionality of spacetime and the value of coupling constants--to gain information on another important aspect: the curvature of spacetime. We investigate the emission of Hawking radiation from a D-dimensional Schwarzschild-de Sitter black hole emitted in the form of scalar fields, and employ both analytical and numerical techniques to calculate greybody factors and differential energy emission rates on the brane and in the bulk. The energy emission rate of the black hole is significantly enhanced in the high-energy regime with the number of spacelike dimensions. On the other hand, in the low-energy part of the spectrum, it is the cosmological constant that leaves a clear footprint, through a characteristic, constant emission rate of ultrasoft quanta determined by the values of black hole and cosmological horizons. Our results are applicable to 'small' black holes arising in theories with an arbitrary number and size of extra dimensions, as well as to pure 4-dimensional primordial black holes, embedded in a de Sitter spacetime

Computed temperature profile in materials exposed to gamma radiation

Energy Technology Data Exchange (ETDEWEB)

Ping, Tso Chin; Choong, Yap Siew; Seon, Chan Kam

1987-06-01

Computed temperature profiles are presented for the materials of lead, steel, concrete and water in curved shells, when they are exposed to gamma radiation. The results are based on the usual simplified theory of thermal conduction with an exponential heat source.

Bulk-memory processor for data acquisition

International Nuclear Information System (INIS)

Nelson, R.O.; McMillan, D.E.; Sunier, J.W.; Meier, M.; Poore, R.V.

1981-01-01

To meet the diverse needs and data rate requirements at the Van de Graaff and Weapons Neutron Research (WNR) facilities, a bulk memory system has been implemented which includes a fast and flexible processor. This bulk memory processor (BMP) utilizes bit slice and microcode techniques and features a 24 bit wide internal architecture allowing direct addressing of up to 16 megawords of memory and histogramming up to 16 million counts per channel without overflow. The BMP is interfaced to the MOSTEK MK 8000 bulk memory system and to the standard MODCOMP computer I/O bus. Coding for the BMP both at the microcode level and with macro instructions is supported. The generalized data acquisition system has been extended to support the BMP in a manner transparent to the user

Apparatus for measuring moisture in moving bulk material using a lithium-7 radiation source

International Nuclear Information System (INIS)

Ashe, J.B.

1976-01-01

A nucleonic device is described for measuring the moisture content of bulk materials using a radioisotopic fast-neutron source such as lithium-7 admixed with an alpha-particle emitter such as americium-241 as a means of minimizing the thickness of the layer of bulk material required proximate to the moisture sensor for a neutron-reflection moisture gauge for proper operation of said gauge. Minimization of the required thickness of the bulk material permits use of a neutron-reflection moisture gauge for measurements of bulk materials on lightly-loaded belts and other types of conveyors where measurements have previously been impracticable

Line-Enhanced Deformable Registration of Pulmonary Computed Tomography Images Before and After Radiation Therapy With Radiation-Induced Fibrosis

Science.gov (United States)

Sensakovic, William F.; Maxim, Peter; Diehn, Maximilian; Loo, Billy W.; Xing, Lei

2018-01-01

Purpose: The deformable registration of pulmonary computed tomography images before and after radiation therapy is challenging due to anatomic changes from radiation fibrosis. We hypothesize that a line-enhanced registration algorithm can reduce landmark error over the entire lung, including the irradiated regions, when compared to an intensity-based deformable registration algorithm. Materials: Two intensity-based B-spline deformable registration algorithms of pre-radiation therapy and post-radiation therapy images were compared. The first was a control intensity–based algorithm that utilized computed tomography images without modification. The second was a line enhancement algorithm that incorporated a Hessian-based line enhancement filter prior to deformable image registration. Registrations were evaluated based on the landmark error between user-identified landmark pairs and the overlap ratio. Results: Twenty-one patients with pre-radiation therapy and post-radiation therapy scans were included. The median time interval between scans was 1.2 years (range: 0.3-3.3 years). Median landmark errors for the line enhancement algorithm were significantly lower than those for the control algorithm over the entire lung (1.67 vs 1.83 mm; P 5 Gy (2.25 vs 3.31; P 5 Gy dose interval demonstrated a significant inverse relationship with post-radiation therapy fibrosis enhancement after line enhancement filtration (Pearson correlation coefficient = −0.48; P = .03). Conclusion: The line enhancement registration algorithm is a promising method for registering images before and after radiation therapy. PMID:29343206

Three-dimensional monochromatic x-ray computed tomography using synchrotron radiation

Science.gov (United States)

Saito, Tsuneo; Kudo, Hiroyuki; Takeda, Tohoru; Itai, Yuji; Tokumori, Kenji; Toyofuku, Fukai; Hyodo, Kazuyuki; Ando, Masami; Nishimura, Katsuyuki; Uyama, Chikao

1998-08-01

We describe a technique of 3D computed tomography (3D CT) using monochromatic x rays generated by synchrotron radiation, which performs a direct reconstruction of a 3D volume image of an object from its cone-beam projections. For the development, we propose a practical scanning orbit of the x-ray source to obtain complete 3D information on an object, and its corresponding 3D image reconstruction algorithm. The validity and usefulness of the proposed scanning orbit and reconstruction algorithm were confirmed by computer simulation studies. Based on these investigations, we have developed a prototype 3D monochromatic x-ray CT using synchrotron radiation, which provides exact 3D reconstruction and material-selective imaging by using the K-edge energy subtraction technique.

WE-DE-202-00: Connecting Radiation Physics with Computational Biology

International Nuclear Information System (INIS)

2016-01-01

Radiation therapy for the treatment of cancer has been established as a highly precise and effective way to eradicate a localized region of diseased tissue. To achieve further significant gains in the therapeutic ratio, we need to move towards biologically optimized treatment planning. To achieve this goal, we need to understand how the radiation-type dependent patterns of induced energy depositions within the cell (physics) connect via molecular, cellular and tissue reactions to treatment outcome such as tumor control and undesirable effects on normal tissue. Several computational biology approaches have been developed connecting physics to biology. Monte Carlo simulations are the most accurate method to calculate physical dose distributions at the nanometer scale, however simulations at the DNA scale are slow and repair processes are generally not simulated. Alternative models that rely on the random formation of individual DNA lesions within one or two turns of the DNA have been shown to reproduce the clusters of DNA lesions, including single strand breaks (SSBs), double strand breaks (DSBs) without the need for detailed track structure simulations. Efficient computational simulations of initial DNA damage induction facilitate computational modeling of DNA repair and other molecular and cellular processes. Mechanistic, multiscale models provide a useful conceptual framework to test biological hypotheses and help connect fundamental information about track structure and dosimetry at the sub-cellular level to dose-response effects on larger scales. In this symposium we will learn about the current state of the art of computational approaches estimating radiation damage at the cellular and sub-cellular scale. How can understanding the physics interactions at the DNA level be used to predict biological outcome? We will discuss if and how such calculations are relevant to advance our understanding of radiation damage and its repair, or, if the underlying biological

WE-DE-202-00: Connecting Radiation Physics with Computational Biology

Energy Technology Data Exchange (ETDEWEB)

NONE

2016-06-15

Radiation therapy for the treatment of cancer has been established as a highly precise and effective way to eradicate a localized region of diseased tissue. To achieve further significant gains in the therapeutic ratio, we need to move towards biologically optimized treatment planning. To achieve this goal, we need to understand how the radiation-type dependent patterns of induced energy depositions within the cell (physics) connect via molecular, cellular and tissue reactions to treatment outcome such as tumor control and undesirable effects on normal tissue. Several computational biology approaches have been developed connecting physics to biology. Monte Carlo simulations are the most accurate method to calculate physical dose distributions at the nanometer scale, however simulations at the DNA scale are slow and repair processes are generally not simulated. Alternative models that rely on the random formation of individual DNA lesions within one or two turns of the DNA have been shown to reproduce the clusters of DNA lesions, including single strand breaks (SSBs), double strand breaks (DSBs) without the need for detailed track structure simulations. Efficient computational simulations of initial DNA damage induction facilitate computational modeling of DNA repair and other molecular and cellular processes. Mechanistic, multiscale models provide a useful conceptual framework to test biological hypotheses and help connect fundamental information about track structure and dosimetry at the sub-cellular level to dose-response effects on larger scales. In this symposium we will learn about the current state of the art of computational approaches estimating radiation damage at the cellular and sub-cellular scale. How can understanding the physics interactions at the DNA level be used to predict biological outcome? We will discuss if and how such calculations are relevant to advance our understanding of radiation damage and its repair, or, if the underlying biological

Radiation dosimetry of computed tomography x-ray scanners

International Nuclear Information System (INIS)

Poletti, J.L.; Williamson, B.D.P.; Le Heron, J.C.

1983-01-01

This report describes the development and application of the methods employed in National Radiation Laboratory (NRL) surveys of computed tomography x-ray scanners (CT scanners). It includes descriptions of the phantoms and equipment used, discussion of the various dose parameters measured, the principles of the various dosimetry systems employed and some indication of the doses to occupationally exposed personnel

Radiation doses from computed tomography practice in Johor Bahru, Malaysia

International Nuclear Information System (INIS)

Karim, M.K.A.; Hashim, S.; Bradley, D.A; Bakar, K.A.; Haron, M.R.; Kayun, Z.

2016-01-01

Radiation doses for Computed Tomography (CT) procedures have been reported, encompassing a total of 376 CT examinations conducted in one oncology centre (Hospital Sultan Ismail) and three diagnostic imaging departments (Hospital Sultanah Aminah, Hospital Permai and Hospital Sultan Ismail) at Johor hospital's. In each case, dose evaluations were supported by data from patient questionnaires. Each CT examination and radiation doses were verified using the CT EXPO (Ver. 2.3.1, Germany) simulation software. Results are presented in terms of the weighted computed tomography dose index (CTDI w ), dose length product (DLP) and effective dose (E). The mean values of CTDI w , DLP and E were ranged between 7.6±0.1 to 64.8±16.5 mGy, 170.2±79.2 to 943.3±202.3 mGy cm and 1.6±0.7 to 11.2±6.5 mSv, respectively. Optimization techniques in CT are suggested to remain necessary, with well-trained radiology personnel remaining at the forefront of such efforts. - Highlights: • We investigate radiation doses received by patients from CT scan examinations. • We compare data with current national diagnostic reference levels and other references. • Radiation doses from CT were influenced by CT parameter, scanning techniques and patient characteristics.

Cost-effective computational method for radiation heat transfer in semi-crystalline polymers

Science.gov (United States)

Boztepe, Sinan; Gilblas, Rémi; de Almeida, Olivier; Le Maoult, Yannick; Schmidt, Fabrice

2018-05-01

This paper introduces a cost-effective numerical model for infrared (IR) heating of semi-crystalline polymers. For the numerical and experimental studies presented here semi-crystalline polyethylene (PE) was used. The optical properties of PE were experimentally analyzed under varying temperature and the obtained results were used as input in the numerical studies. The model was built based on optically homogeneous medium assumption whereas the strong variation in the thermo-optical properties of semi-crystalline PE under heating was taken into account. Thus, the change in the amount radiative energy absorbed by the PE medium was introduced in the model induced by its temperature-dependent thermo-optical properties. The computational study was carried out considering an iterative closed-loop computation, where the absorbed radiation was computed using an in-house developed radiation heat transfer algorithm -RAYHEAT- and the computed results was transferred into the commercial software -COMSOL Multiphysics- for solving transient heat transfer problem to predict temperature field. The predicted temperature field was used to iterate the thermo-optical properties of PE that varies under heating. In order to analyze the accuracy of the numerical model experimental analyses were carried out performing IR-thermographic measurements during the heating of the PE plate. The applicability of the model in terms of computational cost, number of numerical input and accuracy was highlighted.

Some computer graphical user interfaces in radiation therapy.

Science.gov (United States)

Chow, James C L

2016-03-28

In this review, five graphical user interfaces (GUIs) used in radiation therapy practices and researches are introduced. They are: (1) the treatment time calculator, superficial X-ray treatment time calculator (SUPCALC) used in the superficial X-ray radiation therapy; (2) the monitor unit calculator, electron monitor unit calculator (EMUC) used in the electron radiation therapy; (3) the multileaf collimator machine file creator, sliding window intensity modulated radiotherapy (SWIMRT) used in generating fluence map for research and quality assurance in intensity modulated radiation therapy; (4) the treatment planning system, DOSCTP used in the calculation of 3D dose distribution using Monte Carlo simulation; and (5) the monitor unit calculator, photon beam monitor unit calculator (PMUC) used in photon beam radiation therapy. One common issue of these GUIs is that all user-friendly interfaces are linked to complex formulas and algorithms based on various theories, which do not have to be understood and noted by the user. In that case, user only needs to input the required information with help from graphical elements in order to produce desired results. SUPCALC is a superficial radiation treatment time calculator using the GUI technique to provide a convenient way for radiation therapist to calculate the treatment time, and keep a record for the skin cancer patient. EMUC is an electron monitor unit calculator for electron radiation therapy. Instead of doing hand calculation according to pre-determined dosimetric tables, clinical user needs only to input the required drawing of electron field in computer graphical file format, prescription dose, and beam parameters to EMUC to calculate the required monitor unit for the electron beam treatment. EMUC is based on a semi-experimental theory of sector-integration algorithm. SWIMRT is a multileaf collimator machine file creator to generate a fluence map produced by a medical linear accelerator. This machine file controls

Radiation exposure of infants and children in computed tomography

International Nuclear Information System (INIS)

Schmidt, T.; Stieve, F.E.

1980-01-01

The radiation exposure of infants and small children with Computed Tomography is different in several aspects from that of adults undergoing an identical examination. The surface dose at radiation entrance is higher in children because of a smaller body diameter for the same dose rate at the tube. The critical organ dose in the directly irradiated area is higher in children than in adults. The exposure of organs outside the examined area is also higher in children -because of short intervals- than in adults. The absorbed energy, i.e. integral dose, however, is lower in children than in adults because of the lesser volume. The differences between conventional procedures and Computed Tomography, are greater in children than in adults. Here, CT shows higher values than conventional explorations. As a result of the low number of examinations with CT, the contribution towards a genetically significant dose is currently, at least, relatively small [fr

Bulk viscosity, interaction and the viability of phantom solutions

Energy Technology Data Exchange (ETDEWEB)

Leyva, Yoelsy; Sepulveda, Mirko [Universidad de Tarapaca, Departamento de Fisica, Facultad de Ciencias, Arica (Chile)

2017-06-15

We study the dynamics of a bulk viscosity model in the Eckart approach for a spatially flat Friedmann-Robertson-Walker (FRW) Universe. We have included radiation and dark energy, assumed as perfect fluids, and dark matter treated as an imperfect fluid having bulk viscosity. We also introduce an interaction term between the dark matter and dark energy components. Considering that the bulk viscosity is proportional to the dark matter energy density and imposing a complete cosmological dynamics, we find bounds on the bulk viscosity in order to reproduce a matter-dominated era (MDE). This constraint is independent of the interaction term. Some late time phantom solutions are mathematically possible. However, the constraint imposed by a MDE restricts the interaction parameter, in the phantom solutions, to a region consistent with a null value, eliminating the possibility of late time stable solutions with w < -1. From the different cases that we study, the only possible scenario, with bulk viscosity and interaction term, belongs to the quintessence region. In the latter case, we find bounds on the interaction parameter compatible with latest observational data. (orig.)

Hawking Radiation from a (4+n)-dimensional Black Hole Exact Results for the Schwarzschild Phase

CERN Document Server

Harris, C M; Harris, Chris M.; Kanti, Panagiota

2003-01-01

We start our analysis by deriving a master equation that describes the motion of a field with arbitrary spin $s$ on a 3-brane embedded in a non-rotating, uncharged (4+n)-dimensional black hole background. By numerical analysis, we derive exact results for the greybody factors and emission rates for scalars, fermions and gauge bosons emitted directly on the brane, for all energy regimes and for an arbitrary number $n$ of extra dimensions. The relative emissivities on the brane for different types of particles are computed and their dependence on the dimensionality of spacetime is demonstrated -- we therefore conclude that both the amount and the type of radiation emitted can be used for the determination of $n$ if the Hawking radiation from these black holes is observed. The emission of scalar modes in the bulk from the same black holes is also studied and the relative bulk-to-brane energy emissivity is accurately computed. We demonstrate that this quantity varies considerably with $n$ but always remains small...

Methods and compositions for protection of cells and tissues from computed tomography radiation

Energy Technology Data Exchange (ETDEWEB)

Grdina, David J.

2018-01-30

Described are methods for preventing or inhibiting genomic instability and in cells affected by diagnostic radiology procedures employing ionizing radiation. Embodiments include methods of preventing or inhibiting genomic instability and in cells affected by computed tomography (CT) radiation. Subjects receiving ionizing radiation may be those persons suspected of having cancer, or cancer patients having received or currently receiving cancer therapy, and or those patients having received previous ionizing radiation, including those who are approaching or have exceeded the recommended total radiation dose for a person.

Radiation doses from computed tomography in Australia

International Nuclear Information System (INIS)

Thomson, J.E.M.; Tingey, D.R.C.

1997-11-01

Recent surveys in various countries have shown that computed tomography (CT) is a significant and growing contributor to the radiation dose from diagnostic radiology. Australia, with 332 CT scanners (18 per million people), is well endowed with CT equipment compared to European countries (6 to 13 per million people). Only Japan, with 8500 units (78 per million people), has a significantly higher proportion of CT scanners. In view of this, a survey of CT facilities, frequency of examinations, techniques and patient doses has been performed in Australia. It is estimated that there are 1 million CT examinations in Australia each year, resulting in a collective effective dose of 7000 Sv and a per caput dose of 0.39 mSv. This per caput dose is much larger than found in earlier studies in the UK and New Zealand but is less than 0.48 mSv in Japan. Using the ICRP risk factors, radiation doses from CT could be inducing about 280 fatal cancers per year in Australia. CT is therefore a significant, if not the major, single contributor to radiation doses and possible risk from diagnostic radiology. (authors)

Effect of bulk modulus on deformation of the brain under rotational accelerations

Science.gov (United States)

Ganpule, S.; Daphalapurkar, N. P.; Cetingul, M. P.; Ramesh, K. T.

2018-01-01

Traumatic brain injury such as that developed as a consequence of blast is a complex injury with a broad range of symptoms and disabilities. Computational models of brain biomechanics hold promise for illuminating the mechanics of traumatic brain injury and for developing preventive devices. However, reliable material parameters are needed for models to be predictive. Unfortunately, the properties of human brain tissue are difficult to measure, and the bulk modulus of brain tissue in particular is not well characterized. Thus, a wide range of bulk modulus values are used in computational models of brain biomechanics, spanning up to three orders of magnitude in the differences between values. However, the sensitivity of these variations on computational predictions is not known. In this work, we study the sensitivity of a 3D computational human head model to various bulk modulus values. A subject-specific human head model was constructed from T1-weighted MRI images at 2-mm3 voxel resolution. Diffusion tensor imaging provided data on spatial distribution and orientation of axonal fiber bundles for modeling white matter anisotropy. Non-injurious, full-field brain deformations in a human volunteer were used to assess the simulated predictions. The comparison suggests that a bulk modulus value on the order of GPa gives the best agreement with experimentally measured in vivo deformations in the human brain. Further, simulations of injurious loading suggest that bulk modulus values on the order of GPa provide the closest match with the clinical findings in terms of predicated injured regions and extent of injury.

Phase space analysis for anisotropic universe with nonlinear bulk viscosity

Science.gov (United States)

Sharif, M.; Mumtaz, Saadia

2018-06-01

In this paper, we discuss phase space analysis of locally rotationally symmetric Bianchi type I universe model by taking a noninteracting mixture of dust like and viscous radiation like fluid whose viscous pressure satisfies a nonlinear version of the Israel-Stewart transport equation. An autonomous system of equations is established by defining normalized dimensionless variables. In order to investigate stability of the system, we evaluate corresponding critical points for different values of the parameters. We also compute power-law scale factor whose behavior indicates different phases of the universe model. It is found that our analysis does not provide a complete immune from fine-tuning because the exponentially expanding solution occurs only for a particular range of parameters. We conclude that stable solutions exist in the presence of nonlinear model for bulk viscosity with different choices of the constant parameter m for anisotropic universe.

Use of a radiation therapy treatment planning computer in a hospital health physics program

International Nuclear Information System (INIS)

Addison, S.J.

1984-01-01

An onsite treatment planning computer has become state of the art in the care of radiation therapy patients, but in most installations the computer is used for therapy planning a diminutive amount of the day. At St. Mary's Hospital, arrangements have been negotiated for part time use of the treatment planning computer for health physics purposes. Computerized Medical Systems, Inc. (CMS) produces the Modulex radiotherapy planning system which is programmed in MUMPS, a user oriented language specially adapted for handling text string information. St. Mary's Hospital's CMS computer has currently been programmed to assist in data collection and write-up of diagnostic x-ray surveys, meter calibrations, and wipe/leak tests. The computer is setup to provide timely reminders of tests and surveys, and billing for consultation work. Programs are currently being developed for radionuclide inventories. Use of a therapy planning computer for health physics purposes can enhance the radiation safety program and provide additional grounds for the acquisition of such a computer system

Assessment of BSRN radiation records for the computation of monthly means

Science.gov (United States)

Roesch, A.; Wild, M.; Ohmura, A.; Dutton, E. G.; Long, C. N.; Zhang, T.

2011-02-01

The integrity of the Baseline Surface Radiation Network (BSRN) radiation monthly averages are assessed by investigating the impact on monthly means due to the frequency of data gaps caused by missing or discarded high time resolution data. The monthly statistics, especially means, are considered to be important and useful values for climate research, model performance evaluations and for assessing the quality of satellite (time- and space-averaged) data products. The study investigates the spread in different algorithms that have been applied for the computation of monthly means from 1-min values. The paper reveals that the computation of monthly means from 1-min observations distinctly depends on the method utilized to account for the missing data. The intra-method difference generally increases with an increasing fraction of missing data. We found that a substantial fraction of the radiation fluxes observed at BSRN sites is either missing or flagged as questionable. The percentage of missing data is 4.4%, 13.0%, and 6.5% for global radiation, direct shortwave radiation, and downwelling longwave radiation, respectively. Most flagged data in the shortwave are due to nighttime instrumental noise and can reasonably be set to zero after correcting for thermal offsets in the daytime data. The study demonstrates that the handling of flagged data clearly impacts on monthly mean estimates obtained with different methods. We showed that the spread of monthly shortwave fluxes is generally clearly higher than for downwelling longwave radiation. Overall, BSRN observations provide sufficient accuracy and completeness for reliable estimates of monthly mean values. However, the value of future data could be further increased by reducing the frequency of data gaps and the number of outliers. It is shown that two independent methods for accounting for the diurnal and seasonal variations in the missing data permit consistent monthly means to within less than 1 W m-2 in most cases

State of Theory and Computer Simulations of Radiation Effects in Ceramics

International Nuclear Information System (INIS)

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

The Radiation Safety Information Computational Center (RSICC): A Resource for Nuclear Science Applications

International Nuclear Information System (INIS)

Kirk, Bernadette Lugue

2009-01-01

The Radiation Safety Information Computational Center (RSICC) has been in existence since 1963. RSICC collects, organizes, evaluates and disseminates technical information (software and nuclear data) involving the transport of neutral and charged particle radiation, and shielding and protection from the radiation associated with: nuclear weapons and materials, fission and fusion reactors, outer space, accelerators, medical facilities, and nuclear waste management. RSICC serves over 12,000 scientists and engineers from about 100 countries. An important activity of RSICC is its participation in international efforts on computational and experimental benchmarks. An example is the Shielding Integral Benchmarks Archival Database (SINBAD), which includes shielding benchmarks for fission, fusion and accelerators. RSICC is funded by the United States Department of Energy, Department of Homeland Security and Nuclear Regulatory Commission.

Modelling terahertz radiation absorption and reflection with computational phantoms of skin and associated appendages

Science.gov (United States)

Vilagosh, Zoltan; Lajevardipour, Alireza; Wood, Andrew

2018-01-01

Finite-difference time-domain (FDTD) computational phantoms aid the analysis of THz radiation interaction with human skin. The presented computational phantoms have accurate anatomical layering and electromagnetic properties. A novel "large sheet" simulation technique is used allowing for a realistic representation of lateral absorption and reflection of in-vivo measurements. Simulations carried out to date have indicated that hair follicles act as THz propagation channels and confirms the possible role of melanin, both in nevi and skin pigmentation, to act as a significant absorber of THz radiation. A novel freezing technique has promise in increasing the depth of skin penetration of THz radiation to aid diagnostic imaging.

Computational hybrid anthropometric paediatric phantom library for internal radiation dosimetry

DEFF Research Database (Denmark)

Xie, Tianwu; Kuster, Niels; Zaidi, Habib

2017-01-01

for children demonstrated that they follow the same trend when correlated with age. The constructed hybrid computational phantom library opens up the prospect of comprehensive radiation dosimetry calculations and risk assessment for the paediatric population of different age groups and diverse anthropometric...

Computer codes in nuclear safety, radiation transport and dosimetry

International Nuclear Information System (INIS)

Bordy, J.M.; Kodeli, I.; Menard, St.; Bouchet, J.L.; Renard, F.; Martin, E.; Blazy, L.; Voros, S.; Bochud, F.; Laedermann, J.P.; Beaugelin, K.; Makovicka, L.; Quiot, A.; Vermeersch, F.; Roche, H.; Perrin, M.C.; Laye, F.; Bardies, M.; Struelens, L.; Vanhavere, F.; Gschwind, R.; Fernandez, F.; Quesne, B.; Fritsch, P.; Lamart, St.; Crovisier, Ph.; Leservot, A.; Antoni, R.; Huet, Ch.; Thiam, Ch.; Donadille, L.; Monfort, M.; Diop, Ch.; Ricard, M.

2006-01-01

The purpose of this conference was to describe the present state of computer codes dedicated to radiation transport or radiation source assessment or dosimetry. The presentations have been parted into 2 sessions: 1) methodology and 2) uses in industrial or medical or research domains. It appears that 2 different calculation strategies are prevailing, both are based on preliminary Monte-Carlo calculations with data storage. First, quick simulations made from a database of particle histories built though a previous Monte-Carlo simulation and secondly, a neuronal approach involving a learning platform generated through a previous Monte-Carlo simulation. This document gathers the slides of the presentations

Running with rugby balls: bulk renormalization of codimension-2 branes

Science.gov (United States)

Williams, M.; Burgess, C. P.; van Nierop, L.; Salvio, A.

2013-01-01

We compute how one-loop bulk effects renormalize both bulk and brane effective interactions for geometries sourced by codimension-two branes. We do so by explicitly integrating out spin-zero, -half and -one particles in 6-dimensional Einstein-Maxwell-Scalar theories compactified to 4 dimensions on a flux-stabilized 2D geometry. (Our methods apply equally well for D dimensions compactified to D - 2 dimensions, although our explicit formulae do not capture all divergences when D > 6.) The renormalization of bulk interactions are independent of the boundary conditions assumed at the brane locations, and reproduce standard heat-kernel calculations. Boundary conditions at any particular brane do affect how bulk loops renormalize this brane's effective action, but not the renormalization of other distant branes. Although we explicitly compute our loops using a rugby ball geometry, because we follow only UV effects our results apply more generally to any geometry containing codimension-two sources with conical singularities. Our results have a variety of uses, including calculating the UV sensitivity of one-loop vacuum energy seen by observers localized on the brane. We show how these one-loop effects combine in a surprising way with bulk back-reaction to give the complete low-energy effective cosmological constant, and comment on the relevance of this calculation to proposed applications of codimension-two 6D models to solutions of the hierarchy and cosmological constant problems.

Computer simulation of heating of biological tissue during laser radiation

International Nuclear Information System (INIS)

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)

Using a progress computer for the direct acquisition and processing of radiation protection data

International Nuclear Information System (INIS)

Barz, H.G.; Borchardt, K.D.; Hacke, J.; Kirschfeld, K.E.; Kluppak, B.

1976-01-01

A process computer will be used in the Hahn-Meitner-Institute to rationalize radiation protection measures. Appr. 150 transmitters are to be connected with this computer. Especially the radiation measuring devices of a nuclear reactor, of hot cells, and of a heavy ion accelerator, as well as the emission- and environment monitoring systems will be connected. The advantages of this method are described: central data acquisition, central alarm and stoppage information, data processing of certain measurement values, possibility of quick disturbance analysis. Furthermore the authors report about the preparations already finished, particularly about data transmission of digital and analog values to the computer. (orig./HP) [de

Los Alamos radiation transport code system on desktop computing platforms

International Nuclear Information System (INIS)

Briesmeister, J.F.; Brinkley, F.W.; Clark, B.A.; West, J.T.

1990-01-01

The Los Alamos Radiation Transport Code System (LARTCS) consists of state-of-the-art Monte Carlo and discrete ordinates transport codes and data libraries. These codes were originally developed many years ago and have undergone continual improvement. With a large initial effort and continued vigilance, the codes are easily portable from one type of hardware to another. The performance of scientific work-stations (SWS) has evolved to the point that such platforms can be used routinely to perform sophisticated radiation transport calculations. As the personal computer (PC) performance approaches that of the SWS, the hardware options for desk-top radiation transport calculations expands considerably. The current status of the radiation transport codes within the LARTCS is described: MCNP, SABRINA, LAHET, ONEDANT, TWODANT, TWOHEX, and ONELD. Specifically, the authors discuss hardware systems on which the codes run and present code performance comparisons for various machines

Unified bulk-boundary correspondence for band insulators

Science.gov (United States)

Rhim, Jun-Won; Bardarson, Jens H.; Slager, Robert-Jan

2018-03-01

The bulk-boundary correspondence, a topic of intensive research interest over the past decades, is one of the quintessential ideas in the physics of topological quantum matter. Nevertheless, it has not been proven in all generality and has in certain scenarios even been shown to fail, depending on the boundary profiles of the terminated system. Here, we introduce bulk numbers that capture the exact number of in-gap modes, without any such subtleties in one spatial dimension. Similarly, based on these 1D bulk numbers, we define a new 2D winding number, which we call the pole winding number, that specifies the number of robust metallic surface bands in the gap as well as their topological character. The underlying general methodology relies on a simple continuous extrapolation from the bulk to the boundary, while tracking the evolution of Green's function's poles in the vicinity of the bulk band edges. As a main result we find that all the obtained numbers can be applied to the known insulating phases in a unified manner regardless of the specific symmetries. Additionally, from a computational point of view, these numbers can be effectively evaluated without any gauge fixing problems. In particular, we directly apply our bulk-boundary correspondence construction to various systems, including 1D examples without a traditional bulk-boundary correspondence, and predict the existence of boundary modes on various experimentally studied graphene edges, such as open boundaries and grain boundaries. Finally, we sketch the 3D generalization of the pole winding number by in the context of topological insulators.

The Radiation Safety Information Computational Center (RSICC): A Resource for Nuclear Science Applications

Energy Technology Data Exchange (ETDEWEB)

Kirk, Bernadette Lugue [ORNL

2009-01-01

The Radiation Safety Information Computational Center (RSICC) has been in existence since 1963. RSICC collects, organizes, evaluates and disseminates technical information (software and nuclear data) involving the transport of neutral and charged particle radiation, and shielding and protection from the radiation associated with: nuclear weapons and materials, fission and fusion reactors, outer space, accelerators, medical facilities, and nuclear waste management. RSICC serves over 12,000 scientists and engineers from about 100 countries.

Radiation microbiology relevant to radiation processing

International Nuclear Information System (INIS)

Tallentire, A.

1979-01-01

The subject is discussed under the following headings: typical background studies involving laboratory models (measurement of radiation responses of different organisms, alone or on or in products; isolation of radiation resistant organisms from products and product environments; measurement of levels of preirradiation microbial contamination ('bioburden')); supplementary studies involving naturally occurring microbial contaminants (unit medical products; microbiological quality assurance; products in bulk; animal diet study). (U.K.)

Brane Gas-Driven Bulk Expansion as a Precursor Stage to Brane Inflation

International Nuclear Information System (INIS)

Shuhmaher, Natalia; Brandenberger, Robert

2006-01-01

We propose a new way of obtaining slow-roll inflation in the context of higher dimensional models motivated by string and M theory. In our model, all extra spatial dimensions are orbifolded. The initial conditions are taken to be a hot dense bulk brane gas which drives an initial phase of isotropic bulk expansion. This phase ends when a weak potential between the orbifold fixed planes begins to dominate. For a wide class of potentials, a period during which the bulk dimensions decrease sufficiently slowly to lead to slow-roll inflation of the three dimensions parallel to the orbifold fixed planes will result. Once the separation between the orbifold fixed planes becomes of the string scale, a repulsive potential due to string effects takes over and leads to a stabilization of the radion modes. The conversion of bulk branes into radiation during the phase of bulk contraction leads to reheating

Methods of computer experiment in gamma-radiation technologies using new radiation sources

CERN Document Server

Bratchenko, M I; Rozhkov, V V

2001-01-01

Presented id the methodology of computer modeling application for physical substantiation of new irradiation technologies and irradiators design work flow. Modeling tasks for irradiation technologies are structured along with computerized methods of their solution and appropriate types of software. Comparative analysis of available packages for Monte-Carlo modeling of electromagnetic processes in media is done concerning their application to irradiation technologies problems. The results of codes approbation and preliminary data on gamma-radiation absorbed dose distributions for nuclides of conventional sources and prospective Europium-based gamma-sources are presented.

The computer code system for reactor radiation shielding in design of nuclear power plant

International Nuclear Information System (INIS)

Li Chunhuai; Fu Shouxin; Liu Guilian

1995-01-01

The computer code system used in reactor radiation shielding design of nuclear power plant includes the source term codes, discrete ordinate transport codes, Monte Carlo and Albedo Monte Carlo codes, kernel integration codes, optimization code, temperature field code, skyshine code, coupling calculation codes and some processing codes for data libraries. This computer code system has more satisfactory variety of codes and complete sets of data library. It is widely used in reactor radiation shielding design and safety analysis of nuclear power plant and other nuclear facilities

Longitudinal and bulk viscosities of Lennard-Jones fluids

Science.gov (United States)

Tankeshwar, K.; Pathak, K. N.; Ranganathan, S.

1996-12-01

Expressions for the longitudinal and bulk viscosities have been derived using Green Kubo formulae involving the time integral of the longitudinal and bulk stress autocorrelation functions. The time evolution of stress autocorrelation functions are determined using the Mori formalism and a memory function which is obtained from the Mori equation of motion. The memory function is of hyperbolic secant form and involves two parameters which are related to the microscopic sum rules of the respective autocorrelation function. We have derived expressions for the zeroth-, second-and fourth- order sum rules of the longitudinal and bulk stress autocorrelation functions. These involve static correlation functions up to four particles. The final expressions for these have been put in a form suitable for numerical calculations using low- order decoupling approximations. The numerical results have been obtained for the sum rules of longitudinal and bulk stress autocorrelation functions. These have been used to calculate the longitudinal and bulk viscosities and time evolution of the longitudinal stress autocorrelation function of the Lennard-Jones fluids over wide ranges of densities and temperatures. We have compared our results with the available computer simulation data and found reasonable agreement.

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

International Nuclear Information System (INIS)

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.

Computational analysis of the atomic size effect in bulk metallic glasses and their liquid precursors

International Nuclear Information System (INIS)

Kokotin, V.; Hermann, H.

2008-01-01

The atomic size effect and its consequences for the ability of multicomponent liquid alloys to form bulk metallic glasses are analyzed in terms of the generalized Bernal's model for liquids, following the hypothesis that maximum density in the liquid state improves the glass-forming ability. The maximum density that can be achieved in the liquid state is studied in the 2(N-1) dimensional parameter space of N-component systems. Computer simulations reveal that the size ratio of largest to smallest atoms are most relevant for achieving the maximum packing for N = 3-5, whereas the number of components plays a minor role. At small size ratio, the maximum packing density can be achieved by different atomic size distributions, whereas for medium size ratios the maximum density is always correlated to a concave size distribution. The relationship of the results to Miracle's efficient cluster packing model is also discussed

Austenitic stainless steel bulk property considerations for fusion reactors

International Nuclear Information System (INIS)

Mattas, R.F.

1979-04-01

The bulk properties of annealed 304, 316, and 20% cold-worked 316 stainless steels are evaluated for the temperature and radiation conditions expected in a near-term fusion reactor. Of interest are the thermophysical properties, void swelling produced by neutron radiaion, and the tensile, creep, and fatigue properties before and after irradiation

Use of radiation in biomaterials science

International Nuclear Information System (INIS)

Benson, Roberto S.

2002-01-01

Radiation is widely used in the biomaterials science for surface modification, sterilization and to improve bulk properties. Radiation is also used to design of biochips, and in situ photopolymerizable of bioadhesives. The energy sources most commonly used in the irradiation of biomaterials are high-energy electrons, gamma radiation, ultraviolet (UV) and visible light. Surface modification involves placement of selective chemical moieties on the surface of a material by chemical reactions to improve biointeraction for cell adhesion and proliferation, hemocompatibility and water absorption. The exposure of a polymer to radiation, especially ionizing radiation, can lead to chain scission or crosslinking with changes in bulk and surface properties. Sterilization by irradiation is designed to inactivate most pathogens from the surface of biomedical devices. An overview of the use of gamma and UV radiation to improve surface tissue compatibility, bulk properties and surface properties for wear resistance, formation of hydrogels and curing dental sealants and bone adhesives is presented. Gamma and vacuum ultraviolet (VUV) irradiated ultrahigh molecular weight polyethylene (UHMWPE) exhibit improvement in surface modulus and hardness. The surface modulus and hardness of UHMWPE showed a dependence on type of radiation, dosage and processing. VUV surface modified e-PTFE vascular grafts exhibit increases in hydrophilicity and improvement towards adhesion of fibrin glue

Use of radiation in biomaterials science

Science.gov (United States)

Benson, Roberto S.

2002-05-01

Radiation is widely used in the biomaterials science for surface modification, sterilization and to improve bulk properties. Radiation is also used to design of biochips, and in situ photopolymerizable of bioadhesives. The energy sources most commonly used in the irradiation of biomaterials are high-energy electrons, gamma radiation, ultraviolet (UV) and visible light. Surface modification involves placement of selective chemical moieties on the surface of a material by chemical reactions to improve biointeraction for cell adhesion and proliferation, hemocompatibility and water absorption. The exposure of a polymer to radiation, especially ionizing radiation, can lead to chain scission or crosslinking with changes in bulk and surface properties. Sterilization by irradiation is designed to inactivate most pathogens from the surface of biomedical devices. An overview of the use of gamma and UV radiation to improve surface tissue compatibility, bulk properties and surface properties for wear resistance, formation of hydrogels and curing dental sealants and bone adhesives is presented. Gamma and vacuum ultraviolet (VUV) irradiated ultrahigh molecular weight polyethylene (UHMWPE) exhibit improvement in surface modulus and hardness. The surface modulus and hardness of UHMWPE showed a dependence on type of radiation, dosage and processing. VUV surface modified e-PTFE vascular grafts exhibit increases in hydrophilicity and improvement towards adhesion of fibrin glue.

Irradiating of Bulk Soybeans: Influence on Their Functional and Sensory Properties for Soyfood Processing

Science.gov (United States)

Chia, Chiew-Ling; Wilson, Lester A.; Boylston, Terri; Perchonok, Michele; French, Stephen

2006-01-01

Soybeans were chosen for lunar and planetary missions, where soybeans will be supplied in bulk or grown locally, due to their nutritive value and ability to produce oil and protein for further food applications. However, soybeans must be processed into foods prior to consumption. Radiation that soybeans would be exposed to during bulk storage prior to and during a Mars mission may influence their germination and functional properties. The influence of radiation includes the affect of surface pasteurization to ensure the astronauts safety from food-borne illnesses (HACCP, CCP), and the affect of the amount of radiation the soybeans receive during a Mars mission. Decreases in the amount of natural antioxidants free radical formation, and oxidation-induced changes in the soybean will influence the nutritional value, texture, color, and aroma of soyfoods. The objective of this study was to determine the influence of pasteurization and sterilization surface radiation on whole soybeans using gamma and electron beam radiation. The influence of 0, 1, 5, 10, and 30kGy on microbial load, germination rate, ease of processing, and quality of soymilk and tofu were determined. Surface radiation of whole dry soybeans using electron beam or gamma rays from 1-30kGy did provide microbial safety for the astronauts. However, the lower dose levels had surviving yeasts and molds. These doses caused oxidative changes that resulted in soymilk and tofu with rancid aromas. GC-MS of the aroma compounds using SPME Headspace confirmed the presence of lipid oxidation compounds. Soybean germination ability was reduced as radiation dosage increased. While lower doses may reduce these problems, the ability to insure microbial safety of bulk soybeans will be lost. Counter measures could include vacuum packaging, nitrogen flushing, added antioxidants, and radiating under freezing conditions. Doses below 1kGy need to be investigated further to determine the influence of the radiation encountered

Computer aided methods in radiation protection. Hungarian-Austrian-Yugoslavian health physicists' meeting. Abstracts

International Nuclear Information System (INIS)

Feher, I.

1985-10-01

There are 59 papers, mainly on 1. Application of computers and computer codes for processing of large amounts of data from personnel dosimetry. 2. Mathematical models and calculations of processes related to radiation protection e.g. dose distributions and radionuclide migration. The papers are published in summary form only. (G.Q.)

Computer experiments with a coarse-grid hydrodynamic climate model

International Nuclear Information System (INIS)

Stenchikov, G.L.

1990-01-01

A climate model is developed on the basis of the two-level Mintz-Arakawa general circulation model of the atmosphere and a bulk model of the upper layer of the ocean. A detailed model of the spectral transport of shortwave and longwave radiation is used to investigate the radiative effects of greenhouse gases. The radiative fluxes are calculated at the boundaries of five layers, each with a pressure thickness of about 200 mb. The results of the climate sensitivity calculations for mean-annual and perpetual seasonal regimes are discussed. The CCAS (Computer Center of the Academy of Sciences) climate model is used to investigate the climatic effects of anthropogenic changes of the optical properties of the atmosphere due to increasing CO 2 content and aerosol pollution, and to calculate the sensitivity to changes of land surface albedo and humidity

Study and application of Dot 3.5 computer code in radiation shielding problems

International Nuclear Information System (INIS)

Otto, A.C.; Mendonca, A.G.; Maiorino, J.R.

1983-01-01

The application of nuclear transportation code S sub(N), Dot 3.5, to radiation shielding problems is revised. Aiming to study the better available option (convergence scheme, calculation mode), of DOT 3.5 computer code to be applied in radiation shielding problems, a standard model from 'Argonne Code Center' was selected and a combination of several calculation options to evaluate the accuracy of the results and the computational time was used, for then to select the more efficient option. To illustrate the versatility and efficacy in the application of the code for tipical shielding problems, the streaming neutrons calculation along a sodium coolant channel is ilustrated. (E.G.) [pt

Readjustment of abdominal computed tomography protocols in a university hospital: impact on radiation dose

Energy Technology Data Exchange (ETDEWEB)

Romano, Ricardo Francisco Tavares; Salvadori, Priscila Silveira; Torres, Lucas Rios; Bretas, Elisa Almeida Sathler; Bekhor, Daniel; Medeiros, Regina Bitelli; D' Ippolito, Giuseppe, E-mail: ricardo.romano@unifesp.br [Universidade Federal de Sao Paulo (EPM/UNIFESP), Sao Paulo, SP (Brazil). Escola Paulista de Medicina; Caldana, Rogerio Pedreschi [Fleury Medicina e Saude, Sao Paulo, SP (Brazil)

2015-09-15

Objective: To assess the reduction of estimated radiation dose in abdominal computed tomography following the implementation of new scan protocols on the basis of clinical suspicion and of adjusted images acquisition parameters. Materials and Methods: Retrospective and prospective review of reports on radiation dose from abdominal CT scans performed three months before (group A - 551 studies) and three months after (group B - 788 studies) implementation of new scan protocols proposed as a function of clinical indications. Also, the images acquisition parameters were adjusted to reduce the radiation dose at each scan phase. The groups were compared for mean number of acquisition phases, mean CTDI{sub vol} per phase, mean DLP per phase, and mean DLP per scan. Results: A significant reduction was observed for group B as regards all the analyzed aspects, as follows: 33.9%, 25.0%, 27.0% and 52.5%, respectively for number of acquisition phases, CTDI{sub vol} per phase, DLP per phase and DLP per scan (p < 0.001). Conclusion: The rational use of abdominal computed tomography scan phases based on the clinical suspicion in conjunction with the adjusted images acquisition parameters allows for a 50% reduction in the radiation dose from abdominal computed tomography scans. (author)

Improving the bulk data transfer experience

Energy Technology Data Exchange (ETDEWEB)

Guok, Chin; Guok, Chin; Lee, Jason R.; Berket, Karlo

2008-05-07

Scientific computations and collaborations increasingly rely on the network to provide high-speed data transfer, dissemination of results, access to instruments, support for computational steering, etc. The Energy Sciences Network is establishing a science data network to provide user driven bandwidth allocation. In a shared network environment, some reservations may not be granted due to the lack of available bandwidth on any single path. In many cases, the available bandwidth across multiple paths would be sufficient to grant the reservation. In this paper we investigate how to utilize the available bandwidth across multiple paths in the case of bulk data transfer.

Anisotropic colloids: bulk phase behavior and equilibrium sedimentation

NARCIS (Netherlands)

Marechal, M.A.T.

2009-01-01

This thesis focuses on the phase behavior of anisotropically shaped (i.e. non-spherical) colloids using computer simulations. Only hard-core interactions between the colloids are taken into account to investigate the effects of shape alone. The bulk phase behavior of three different shapes of

The PEREGRINE ^TM program: using physics and computer simulation to improve radiation therapy for cancer

Energy Technology Data Exchange (ETDEWEB)

Siantar, Christine L. Hartmann [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Moses, Edward I. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

1998-11-01

When using radiation to treat cancer, doctors rely on physics and computer technology to predict where radiation dose will by deposited in the patient. The accuracy of computerized treatment planning plays a critical role in the ultimate success or failure of the radiation treatment. Inaccurate dose calculations can result in either insufficient radiation for cure, or excessive radiation to nearby healthy tissue, which can reduce the patient's quality of life. This article describes how advanced physics, computer, and engineering techniques originally developed for nuclear weapons and high energy physics research are being used to predict radiation dose in cancer patients. Results for radiation therapy planning, achieved in the Lawrence Livermore National Laboratory (LLNL) PEREGRINE program, show that these tools can give doctors new insights into their patients' treatments by providing substantially more accurate dose distributions than have been available in the past. It is believed that greater accuracy in radiation therapy treatment planning will save lives by improving doctors' ability to target radiation to the tumor and reduce suffering by reducing the incidence of radiation-induced complications.

European questionnaire on the use of computer programmes in radiation dosimetry

Energy Technology Data Exchange (ETDEWEB)

Gualdrini, G. [ENEA, Centro Ricerche Ezio Clementel, Bologna (Italy). Dipt. Ambiente; Grosswendt, B.; Siebert, B.R.L. [Braunschweig (Germany); Tanner, R. [NRPB, Dosimetry Development Group, Chilton, Didcot, Oxon (United Kingdom); Terrisol, M. [CPAT, Univ. Paul Sabatier, Toulouse (France)

1999-07-01

Because of a potential reduction of necessary experimental efforts, the combination of measurements and supplementing calculations, also in the field of radiation dosimetry, may allow time and money to be saved if computational methods are used which are well suited to reproduce experimental data in a satisfactory quality. The dramatic increase in computing power in recent years now permits the use of computational tools for dosimetry also in routine applications. Many institutions dealing with radiation protection, however, have small groups which, in addition to their routine work, often cannot afford to specialise in the field of computational dosimetry. This means that not only experts but increasingly also casual users employ complicated computational tools such as general-purpose transport codes. This massive use of computer programmes in radiation protection and dosimetry applications motivated the Concerted Action Investigation and Quality Assurance of Numerical Methods in Radiation Protection Dosimetry of the 4. framework programme of the European Commission to prepare, distribute and evaluate a questionnaire on the use of such codes. A significant number of scientists from nearly all the countries of the European Community (and some countries outside Europe) contributed to the questionnaire, that allowed to obtain a satisfactory overview of the state of the art in this field. The results obtained from the questionnaire and summarised in the present Report are felt to be indicative of the situation of using sophisticated computer codes within the European Community although the group of participating scientist may not be a representative sample in a strict statistical sense. [Italian] A causa della progressiva diminuzione dell'impegno sperimentale, la combinazione di misure e valutazioni numeriche supplementari puo' consentire, anche nel campo della dosimetria delle radiazioni, risparmi di tempo e risorse purche' sia garantito l

Radiation doses from computed tomography practice in Johor Bahru, Malaysia

Science.gov (United States)

Karim, M. K. A.; Hashim, S.; Bradley, D. A.; Bakar, K. A.; Haron, M. R.; Kayun, Z.

2016-04-01

Radiation doses for Computed Tomography (CT) procedures have been reported, encompassing a total of 376 CT examinations conducted in one oncology centre (Hospital Sultan Ismail) and three diagnostic imaging departments (Hospital Sultanah Aminah, Hospital Permai and Hospital Sultan Ismail) at Johor hospital's. In each case, dose evaluations were supported by data from patient questionnaires. Each CT examination and radiation doses were verified using the CT EXPO (Ver. 2.3.1, Germany) simulation software. Results are presented in terms of the weighted computed tomography dose index (CTDIw), dose length product (DLP) and effective dose (E). The mean values of CTDIw, DLP and E were ranged between 7.6±0.1 to 64.8±16.5 mGy, 170.2±79.2 to 943.3±202.3 mGy cm and 1.6±0.7 to 11.2±6.5 mSv, respectively. Optimization techniques in CT are suggested to remain necessary, with well-trained radiology personnel remaining at the forefront of such efforts.

Simulation of radiation effects on three-dimensional computer optical memories

Science.gov (United States)

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.

Computer codes for problems of isotope and radiation research

International Nuclear Information System (INIS)

Remer, M.

1986-12-01

A survey is given of computer codes for problems in isotope and radiation research. Altogether 44 codes are described as titles with abstracts. 17 of them are in the INIS scope and are processed individually. The subjects are indicated in the chapter headings: 1) analysis of tracer experiments, 2) spectrum calculations, 3) calculations of ion and electron trajectories, 4) evaluation of gamma irradiation plants, and 5) general software

Shutdown and degradation: Space computers for nuclear application, verification of radiation hardness. Final report

International Nuclear Information System (INIS)

Eichhorn, E.; Gerber, V.; Schreyer, P.

1995-01-01

(1) Employment of those radiation hard electronics which are already known in military and space applications. (2) The experience in space-flight shall be used to investigate nuclear technology areas, for example, by using space electronics to prove the range of applications in nuclear radiating environments. (3) Reproduction of a computer developed for telecommunication satellites; proof of radiation hardness by radiation tests. (4) At 328 Krad (Si) first failure of radiation tolerant devices with 100 Krad (Si) hardness guaranteed. (5) Using radiation hard devices of the same type you can expect applications at doses of greater than 1 Mrad (Si). Electronic systems applicable for radiation categories D, C and lower part of B for manipulators, vehicles, underwater robotics. (orig.) [de

Hawking radiation spectra for scalar fields by a higher-dimensional Schwarzschild-de Sitter black hole

Science.gov (United States)

Pappas, T.; Kanti, P.; Pappas, N.

2016-07-01

In this work, we study the propagation of scalar fields in the gravitational background of a higher-dimensional Schwarzschild-de Sitter black hole as well as on the projected-on-the-brane four-dimensional background. The scalar fields have also a nonminimal coupling to the corresponding, bulk or brane, scalar curvature. We perform a comprehensive study by deriving exact numerical results for the greybody factors, and study their profile in terms of particle and spacetime properties. We then proceed to derive the Hawking radiation spectra for a higher-dimensional Schwarzschild-de Sitter black hole, and we study both bulk and brane channels. We demonstrate that the nonminimal field coupling, which creates an effective mass term for the fields, suppresses the energy emission rates while the cosmological constant assumes a dual role. By computing the relative energy rates and the total emissivity ratio for bulk and brane emission, we demonstrate that the combined effect of a large number of extra dimensions and value of the field coupling gives to the bulk channel the clear domination in the bulk-brane energy balance.

Verification of Radiation Isocenter on Linac Beam 6 MV using Computed Radiography

Science.gov (United States)

Irsal, Muhammad; Hidayanto, Eko; Sutanto, Heri

2017-06-01

Radiation isocenter is more important part of quality assurance for the linear accelerator (Linac) due to radiation isocenter is a main location in irradiation radiotherapy, isocenter can shift when the gantry and collimator rotation. In general, the radiation isocenter verification using a special film. This research was conducted radiation isocenter verification using computed radiography with digital image processing techniques. Image acquisition was done using the modalities of Linac 6 MV with star shot method is star-shaped beam due to rotation of the collimator, gantry and couch. Then do the delineation on each beam to determine the centroid and beam diameter. By the results of verification of radiation isocenter performed on collimator and the couch, it shows that the size diameter for rotational collimator is 0.632 mm and 0.458 mm for the couch. Based on AAPM report 40 about the size of the Linac radiation isocenter diameter used in this study is still in good condition and worth to be operated because the value of the radiation isocenter diameter is below 2 mm.

Verification of Radiation Isocenter on Linac Beam 6 MV using Computed Radiography

International Nuclear Information System (INIS)

Irsal, Muhammad; Hidayanto, Eko; Sutanto, Heri

2017-01-01

Radiation isocenter is more important part of quality assurance for the linear accelerator (Linac) due to radiation isocenter is a main location in irradiation radiotherapy, isocenter can shift when the gantry and collimator rotation. In general, the radiation isocenter verification using a special film. This research was conducted radiation isocenter verification using computed radiography with digital image processing techniques. Image acquisition was done using the modalities of Linac 6 MV with star shot method is star-shaped beam due to rotation of the collimator, gantry and couch. Then do the delineation on each beam to determine the centroid and beam diameter. By the results of verification of radiation isocenter performed on collimator and the couch, it shows that the size diameter for rotational collimator is 0.632 mm and 0.458 mm for the couch. Based on AAPM report 40 about the size of the Linac radiation isocenter diameter used in this study is still in good condition and worth to be operated because the value of the radiation isocenter diameter is below 2 mm. (paper)

Computer system of radiation control at PNC Tokai Works

International Nuclear Information System (INIS)

Kanamori, Masashi; Ebana, Minoru; Seki, Akio

1984-01-01

In the Power Reactor and Nuclear Fuel Development Corporation (PNC), the operation of the fuel reprocessing plant started in January, 1981, the high level radioactive substance research facility (CPF) was completed in 1982, and the plutonium conversion technique development facility started the actual operation in September, 1983. In this situation, PNC introduced computer systems for radiation control to increase efficiency and to save labor: concretely computer systems were introduced for the continuous monitoring system in CPF in September, 1982, and for the plutonium conversion technique development facility in April, 1983. In this review, radiation control items in CPF are shown. The stationary monitors for continuous monitoring are employed for area monitors and exhaust monitors, while off-line input processing is adopted for batch measurement every week, such as iodine with an off-gas monitor. Batch data processing includes routine smear survey for working environment and shield wall survey. Other area monitors are criticality alarm systems which are designed with 2 out of 3 redundancy. In the second half of the review, the data processing system is described on each item of hardware and software, system configuration, data acquisition and demand input, processing, alarm functions, data recording and CRT display. In the review, also the system evaluation and future problems are described. (Wakatsuki, Y.)

Vision 20/20: Automation and advanced computing in clinical radiation oncology

International Nuclear Information System (INIS)

Moore, Kevin L.; Moiseenko, Vitali; Kagadis, George C.; McNutt, Todd R.; Mutic, Sasa

2014-01-01

This Vision 20/20 paper considers what computational advances are likely to be implemented in clinical radiation oncology in the coming years and how the adoption of these changes might alter the practice of radiotherapy. Four main areas of likely advancement are explored: cloud computing, aggregate data analyses, parallel computation, and automation. As these developments promise both new opportunities and new risks to clinicians and patients alike, the potential benefits are weighed against the hazards associated with each advance, with special considerations regarding patient safety under new computational platforms and methodologies. While the concerns of patient safety are legitimate, the authors contend that progress toward next-generation clinical informatics systems will bring about extremely valuable developments in quality improvement initiatives, clinical efficiency, outcomes analyses, data sharing, and adaptive radiotherapy

Vision 20/20: Automation and advanced computing in clinical radiation oncology

Energy Technology Data Exchange (ETDEWEB)

Moore, Kevin L., E-mail: kevinmoore@ucsd.edu; Moiseenko, Vitali [Department of Radiation Medicine and Applied Sciences, University of California San Diego, La Jolla, California 92093 (United States); Kagadis, George C. [Department of Medical Physics, School of Medicine, University of Patras, Rion, GR 26504 (Greece); McNutt, Todd R. [Department of Radiation Oncology and Molecular Radiation Science, School of Medicine, Johns Hopkins University, Baltimore, Maryland 21231 (United States); Mutic, Sasa [Department of Radiation Oncology, Washington University in St. Louis, St. Louis, Missouri 63110 (United States)

2014-01-15

This Vision 20/20 paper considers what computational advances are likely to be implemented in clinical radiation oncology in the coming years and how the adoption of these changes might alter the practice of radiotherapy. Four main areas of likely advancement are explored: cloud computing, aggregate data analyses, parallel computation, and automation. As these developments promise both new opportunities and new risks to clinicians and patients alike, the potential benefits are weighed against the hazards associated with each advance, with special considerations regarding patient safety under new computational platforms and methodologies. While the concerns of patient safety are legitimate, the authors contend that progress toward next-generation clinical informatics systems will bring about extremely valuable developments in quality improvement initiatives, clinical efficiency, outcomes analyses, data sharing, and adaptive radiotherapy.

Vision 20/20: Automation and advanced computing in clinical radiation oncology.

Science.gov (United States)

Moore, Kevin L; Kagadis, George C; McNutt, Todd R; Moiseenko, Vitali; Mutic, Sasa

2014-01-01

This Vision 20/20 paper considers what computational advances are likely to be implemented in clinical radiation oncology in the coming years and how the adoption of these changes might alter the practice of radiotherapy. Four main areas of likely advancement are explored: cloud computing, aggregate data analyses, parallel computation, and automation. As these developments promise both new opportunities and new risks to clinicians and patients alike, the potential benefits are weighed against the hazards associated with each advance, with special considerations regarding patient safety under new computational platforms and methodologies. While the concerns of patient safety are legitimate, the authors contend that progress toward next-generation clinical informatics systems will bring about extremely valuable developments in quality improvement initiatives, clinical efficiency, outcomes analyses, data sharing, and adaptive radiotherapy.

Direct Computation of Sound Radiation by Jet Flow Using Large-scale Equations

Science.gov (United States)

Mankbadi, R. R.; Shih, S. H.; Hixon, D. R.; Povinelli, L. A.

1995-01-01

Jet noise is directly predicted using large-scale equations. The computational domain is extended in order to directly capture the radiated field. As in conventional large-eddy-simulations, the effect of the unresolved scales on the resolved ones is accounted for. Special attention is given to boundary treatment to avoid spurious modes that can render the computed fluctuations totally unacceptable. Results are presented for a supersonic jet at Mach number 2.1.

PABLM: a computer program to calculate accumulated radiation doses from radionuclides in the environment

Energy Technology Data Exchange (ETDEWEB)

Napier, B.A.; Kennedy, W.E. Jr.; Soldat, J.K.

1980-03-01

A computer program, PABLM, was written to facilitate the calculation of internal radiation doses to man from radionuclides in food products and external radiation doses from radionuclides in the environment. This report contains details of mathematical models used and calculational procedures required to run the computer program. Radiation doses from radionuclides in the environment may be calculated from deposition on the soil or plants during an atmospheric or liquid release, or from exposure to residual radionuclides in the environment after the releases have ended. Radioactive decay is considered during the release of radionuclides, after they are deposited on the plants or ground, and during holdup of food after harvest. The radiation dose models consider several exposure pathways. Doses may be calculated for either a maximum-exposed individual or for a population group. The doses calculated are accumulated doses from continuous chronic exposure. A first-year committed dose is calculated as well as an integrated dose for a selected number of years. The equations for calculating internal radiation doses are derived from those given by the International Commission on Radiological Protection (ICRP) for body burdens and MPC's of each radionuclide. The radiation doses from external exposure to contaminated water and soil are calculated using the basic assumption that the contaminated medium is large enough to be considered an infinite volume or plane relative to the range of the emitted radiations. The equations for calculations of the radiation dose from external exposure to shoreline sediments include a correction for the finite width of the contaminated beach.

PABLM: a computer program to calculate accumulated radiation doses from radionuclides in the environment

International Nuclear Information System (INIS)

Napier, B.A.; Kennedy, W.E. Jr.; Soldat, J.K.

1980-03-01

A computer program, PABLM, was written to facilitate the calculation of internal radiation doses to man from radionuclides in food products and external radiation doses from radionuclides in the environment. This report contains details of mathematical models used and calculational procedures required to run the computer program. Radiation doses from radionuclides in the environment may be calculated from deposition on the soil or plants during an atmospheric or liquid release, or from exposure to residual radionuclides in the environment after the releases have ended. Radioactive decay is considered during the release of radionuclides, after they are deposited on the plants or ground, and during holdup of food after harvest. The radiation dose models consider several exposure pathways. Doses may be calculated for either a maximum-exposed individual or for a population group. The doses calculated are accumulated doses from continuous chronic exposure. A first-year committed dose is calculated as well as an integrated dose for a selected number of years. The equations for calculating internal radiation doses are derived from those given by the International Commission on Radiological Protection (ICRP) for body burdens and MPC's of each radionuclide. The radiation doses from external exposure to contaminated water and soil are calculated using the basic assumption that the contaminated medium is large enough to be considered an infinite volume or plane relative to the range of the emitted radiations. The equations for calculations of the radiation dose from external exposure to shoreline sediments include a correction for the finite width of the contaminated beach

The UF family of hybrid phantoms of the developing human fetus for computational radiation dosimetry

International Nuclear Information System (INIS)

Maynard, Matthew R; Geyer, John W; Bolch, Wesley; Aris, John P; Shifrin, Roger Y

2011-01-01

Historically, the development of computational phantoms for radiation dosimetry has primarily been directed at capturing and representing adult and pediatric anatomy, with less emphasis devoted to models of the human fetus. As concern grows over possible radiation-induced cancers from medical and non-medical exposures of the pregnant female, the need to better quantify fetal radiation doses, particularly at the organ-level, also increases. Studies such as the European Union's SOLO (Epidemiological Studies of Exposed Southern Urals Populations) hope to improve our understanding of cancer risks following chronic in utero radiation exposure. For projects such as SOLO, currently available fetal anatomic models do not provide sufficient anatomical detail for organ-level dose assessment. To address this need, two fetal hybrid computational phantoms were constructed using high-quality magnetic resonance imaging and computed tomography image sets obtained for two well-preserved fetal specimens aged 11.5 and 21 weeks post-conception. Individual soft tissue organs, bone sites and outer body contours were segmented from these images using 3D-DOCTOR(TM) and then imported to the 3D modeling software package Rhinoceros(TM) for further modeling and conversion of soft tissue organs, certain bone sites and outer body contours to deformable non-uniform rational B-spline surfaces. The two specimen-specific phantoms, along with a modified version of the 38 week UF hybrid newborn phantom, comprised a set of base phantoms from which a series of hybrid computational phantoms was derived for fetal ages 8, 10, 15, 20, 25, 30, 35 and 38 weeks post-conception. The methodology used to construct the series of phantoms accounted for the following age-dependent parameters: (1) variations in skeletal size and proportion, (2) bone-dependent variations in relative levels of bone growth, (3) variations in individual organ masses and total fetal masses and (4) statistical percentile variations in

Phenomenology of Bulk Scalar Production at the LHC

CERN Document Server

Beauchemin , Pierre-Hugues; Burgess, Cliff

We examine the sensitivity of the ATLAS detector to extra-dimensional scalars in scenarios having the extra-dimensional Planck scale in the TeV range and n = 2 large extra dimensions. Such scalars appear as partners of the graviton in higher-dimensional supersymmetric theories. Using first the scalar's lowest-dimensional effective couplings to quarks and gluons, we compute the rate of production of a hard jet together with missing energy. We find a nontrivial range of bulk scalar couplings for which ATLAS could observe a signal, and in particular, higher sensitivity to couplings to gluons than to quarks. Bulk scalar emission increases the missing-energy signal by adding to graviton production, and so complicates the inference of the extra-dimensional Planck scale from the observed rate of jet + EmissT . Because bulk scalar differential cross sections resemble those for gravitons, it is unlikely that these can be experimentally distinguished should a missing energy signal be observed. However, given, for examp...

A general method for computing the total solar radiation force on complex spacecraft structures

Science.gov (United States)

Chan, F. K.

1981-01-01

The method circumvents many of the existing difficulties in computational logic presently encountered in the direct analytical or numerical evaluation of the appropriate surface integral. It may be applied to complex spacecraft structures for computing the total force arising from either specular or diffuse reflection or even from non-Lambertian reflection and re-radiation.

A new method of preventing bulk-Si CMOS devices from latchup

International Nuclear Information System (INIS)

Xu Xianguo; Xu Xi

2004-01-01

A new method, pseudo-latchup path method, has been put forward that is based on latchup effects of bulk-Si CMOS devices. After we study the design of pseudo-latchup path method in detail, a practice and the corresponding simulation result by computer are given in this text. Pseudo-latchup path method can be used to prevent permanent latchup, but it cannot be used to eliminate the dose rate upset of bulk-Si CMOS devices. (authors)

Status of radiation processing: Indian scenario

International Nuclear Information System (INIS)

Niyogi, U.K.

2013-01-01

Radiation processing is a technique to process different types of materials by way of providing radiations of different energies for various applications. Depending upon the changes, one needs to select the radiations of appropriate energy. The well established mechanism behind the changes occurring in the material is the excitation of electrons in the molecules and atoms. It is a proven technology for more than five decades which results in the modification in materials, both at the bulk and surface levels. While radiations such as IR and UV have low energy and hence affect the surface of the material only, highly energetic radiations such as gamma and e-beam are useful to modify the material at the bulk level. Radiation processing is the most efficient technique for polymerization, sterilization, disinfestations, etc. which are applied in industries such as wires and cables, healthcare, food processing, pet/animal feed, herbal and ayurvedic, artificial jewellery, etc.

Lithium niobate bulk crystallization promoted by CO2 laser radiation

Science.gov (United States)

Ferreira, N. M.; Costa, F. M.; Nogueira, R. N.; Graça, M. P. F.

2012-09-01

The crystallization induced by laser radiation is a very promising technique to promote glass/ceramic transformation, being already used to produce crystalline patterns on glass surfaces. In this work, a SiO2-Li2O-Nb2O5 glass, prepared by the sol-gel route, was submitted to CO2 laser radiation and conventional heat-treatments in order to induce the LiNbO3 crystallization. The structure and morphology of the samples prepared by both routes was analyzed as a function of exposure time, radiation power and heat-treatment temperatures by XRD, Raman spectroscopy and SEM. The results reveal a correlation between the crystallization degree of LiNbO3 particles and glass matrix with the heat treatment type and experimental parameters. An heat-treatment at 650 °C/4 h was necessary to induce crystallization in heat treatments samples while 4 W/500 s was enough for laser radiation ones, corresponding a reduction time processing of ˜14 000 s.

A smooth and differentiable bulk-solvent model for macromolecular diffraction

Energy Technology Data Exchange (ETDEWEB)

Fenn, T. D. [Department of Molecular and Cellular Physiology and Howard Hughes Medical Institute, Stanford, California (United States); Schnieders, M. J. [Department of Chemistry, Stanford, California (United States); Brunger, A. T., E-mail: brunger@stanford.edu [Department of Molecular and Cellular Physiology and Howard Hughes Medical Institute, Stanford, California (United States); Departments of Neurology and Neurological Sciences, Structural Biology and Photon Science, Stanford, California (United States)

2010-09-01

A new method for modeling the bulk solvent in macromolecular diffraction data based on Babinet’s principle is presented. The proposed models offer the advantage of differentiability with respect to atomic coordinates. Inclusion of low-resolution data in macromolecular crystallography requires a model for the bulk solvent. Previous methods have used a binary mask to accomplish this, which has proven to be very effective, but the mask is discontinuous at the solute–solvent boundary (i.e. the mask value jumps from zero to one) and is not differentiable with respect to atomic parameters. Here, two algorithms are introduced for computing bulk-solvent models using either a polynomial switch or a smoothly thresholded product of Gaussians, and both models are shown to be efficient and differentiable with respect to atomic coordinates. These alternative bulk-solvent models offer algorithmic improvements, while showing similar agreement of the model with the observed amplitudes relative to the binary model as monitored using R, R{sub free} and differences between experimental and model phases. As with the standard solvent models, the alternative models improve the agreement primarily with lower resolution (>6 Å) data versus no bulk solvent. The models are easily implemented into crystallographic software packages and can be used as a general method for bulk-solvent correction in macromolecular crystallography.

A smooth and differentiable bulk-solvent model for macromolecular diffraction

International Nuclear Information System (INIS)

Fenn, T. D.; Schnieders, M. J.; Brunger, A. T.

2010-01-01

A new method for modeling the bulk solvent in macromolecular diffraction data based on Babinet’s principle is presented. The proposed models offer the advantage of differentiability with respect to atomic coordinates. Inclusion of low-resolution data in macromolecular crystallography requires a model for the bulk solvent. Previous methods have used a binary mask to accomplish this, which has proven to be very effective, but the mask is discontinuous at the solute–solvent boundary (i.e. the mask value jumps from zero to one) and is not differentiable with respect to atomic parameters. Here, two algorithms are introduced for computing bulk-solvent models using either a polynomial switch or a smoothly thresholded product of Gaussians, and both models are shown to be efficient and differentiable with respect to atomic coordinates. These alternative bulk-solvent models offer algorithmic improvements, while showing similar agreement of the model with the observed amplitudes relative to the binary model as monitored using R, R free and differences between experimental and model phases. As with the standard solvent models, the alternative models improve the agreement primarily with lower resolution (>6 Å) data versus no bulk solvent. The models are easily implemented into crystallographic software packages and can be used as a general method for bulk-solvent correction in macromolecular crystallography

Development of point Kernel radiation shielding analysis computer program implementing recent nuclear data and graphic user interfaces

International Nuclear Information System (INIS)

Kang, S.; Lee, S.; Chung, C.

2002-01-01

There is an increasing demand for safe and efficient use of radiation and radioactive work activity along with shielding analysis as a result the number of nuclear and conventional facilities using radiation or radioisotope rises. Most Korean industries and research institutes including Korea Power Engineering Company (KOPEC) have been using foreign computer programs for radiation shielding analysis. Korean nuclear regulations have introduced new laws regarding the dose limits and radiological guides as prescribed in the ICRP 60. Thus, the radiation facilities should be designed and operated to comply with these new regulations. In addition, the previous point kernel shielding computer code utilizes antiquated nuclear data (mass attenuation coefficient, buildup factor, etc) which were developed in 1950∼1960. Subsequently, the various nuclear data such mass attenuation coefficient, buildup factor, etc. have been updated during the past few decades. KOPEC's strategic directive is to become a self-sufficient and independent nuclear design technology company, thus KOPEC decided to develop a new radiation shielding computer program that included the latest regulatory requirements and updated nuclear data. This new code was designed by KOPEC with developmental cooperation with Hanyang University, Department of Nuclear Engineering. VisualShield is designed with a graphical user interface to allow even users unfamiliar to radiation shielding theory to proficiently prepare input data sets and analyzing output results

Simulation of radiation effects on three-dimensional computer optical memories

International Nuclear Information System (INIS)

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

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

International Nuclear Information System (INIS)

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

Tumor bulk as a prognostic factor for the management of localized aggressive non-Hodgkin's lymphoma: a survey of the Japan lymphoma radiation therapy group

International Nuclear Information System (INIS)

Oguchi, Masahiko; Ikeda, Hiroshi; Isobe, Kouichi; Hirota, Saeko; Hasegawa, Masatoshi; Nakamura, Katsumasa; Sasai, Keisuke; Hayabuchi, Naofumi

2000-01-01

Purpose: To identify the prognostic factors that specifically predict survival rates of patients with localized aggressive non-Hodgkin's lymphoma (NHL). Methods and Materials: The survey was carried out at 25 radiation oncology institutions in Japan in 1998. The 5-year event-free (EFS) and overall survival rates (OAS) were calculated, and univariate and multivariate analyses were done to identify which of the following factors, namely, gender, age, performance status (PS), serum lactate dehydrogenase (LDH) level, Stage (I vs. II), tumor bulk (maximum diameter), and treatment, were significant from the viewpoint of prognosis. Results: A total of 1141 patients with Stage I and II NHL were treated by the Japanese Lymphoma Radiation Therapy Group between 1988 and 1992. Of them, 787 patients, who were treated using definitive radiotherapy with or without chemotherapy for intermediate- and high-grade lymphomas in working formulation, constituted the core of this study. Primary tumors arose mainly from extranodal organs (71%) in the head and neck (Waldeyer's ring: 36% and sinonasal cavities: 9%). The factors associated with poorer prognosis were age over 60 years old (p < 0.0001), radiation therapy alone (p < 0.0001), PS = 2-4 (p = 0.0011), (sex male, p = 0.0078), a bulky tumor more than 6 cm in maximum diameter (p 0.0088), elevated LDH (p = 0.0117), and stage II (p = 0.0642). A median dose of 42 Gy was delivered mainly to the involved fields. Short-course chemotherapy was provided in 549 (70%) patients. The 5-year OAS and EFS rates for all patients were 71% and 67%, respectively. According to the stage-modified International Prognostic Index, the 5-year EFS of the patients with risk factors from 0 to 1 was 76%, 61% for patients with two risk factors, and 26% for patients with three or more risk factors. Conclusion: Extranodal presentation, especially Waldeyer's ring and sinonasal cavities, is encountered more frequently in Japan than in Western countries. Tumor bulk is

Photoelectric-enhanced radiation therapy with quasi-monochromatic computed tomography.

Science.gov (United States)

Jost, Gregor; Mensing, Tristan; Golfier, Sven; Lawaczeck, Rüdiger; Pietsch, Hubertus; Hütter, Joachim; Cibik, Levent; Gerlach, Martin; Krumrey, Michael; Fratzscher, Daniel; Arkadiev, Vladimir; Wedell, Reiner; Haschke, Michael; Langhoff, Norbert; Wust, Peter; Lüdemann, Lutz

2009-06-01

Photoelectric-enhanced radiation therapy is a bimodal therapy, consisting of the administration of highly radiation-absorbing substances into the tumor area and localized regional irradiation with orthovoltage x-rays. Irradiation can be performed by a modified computed tomography (CT) unit equipped with an additional x-ray optical module which converts the polychromatic, fan-shaped CT beam into a monochromatized and focused beam for energy-tuned photoelectric-enhanced radiotherapy. A dedicated x-ray optical module designed for spatial collimation, focusing, and monochromatization was mounted at the exit of the x-ray tube of a clinical CT unit. Spectrally resolved measurements of the resulting beam were performed using an energy-dispersive detection system calibrated by synchrotron radiation. The spatial photon fluence was determined by film dosimetry. Depth-dose measurements were performed and compared to the polychromatic CT and a therapeutic 6 MV beam. The spatial dose distribution in phantoms using a rotating radiation source (quasimonochromatic CT and 6 MV, respectively) was investigated by gel dosimetry. The photoelectric dose enhancement for an iodine fraction of 1% in tissue was calculated and verified experimentally. The x-ray optical module selectively filters the energy of the tungsten Kalpha emission line with an FWHM of 5 keV. The relative photon fluence distribution demonstrates the focusing characteristic of the x-ray optical module. A beam width of about 3 mm was determined at the isocenter of the CT gantry. The depth-dose measurements resulted in a half-depth value of approximately 36 mm for the CT beams (quasi-monochromatic, polychromatic) compared to 154 mm for the 6 MV beam. The rotation of the radiation source leads to a steep dose gradient at the center of rotation; the gel dosimetry yields an entrance-to-peak dose ratio of 1:10.8 for the quasi-monochromatic CT and 1:37.3 for a 6 MV beam of the same size. The photoelectric dose enhancement

Photoelectric-enhanced radiation therapy with quasi-monochromatic computed tomography

International Nuclear Information System (INIS)

Jost, Gregor; Mensing, Tristan; Golfier, Sven; Lawaczeck, Ruediger; Pietsch, Hubertus; Huetter, Joachim; Cibik, Levent; Gerlach, Martin; Krumrey, Michael; Fratzscher, Daniel; Arkadiev, Vladimir; Wedell, Reiner; Haschke, Michael; Langhoff, Norbert; Wust, Peter; Luedemann, Lutz

2009-01-01

Photoelectric-enhanced radiation therapy is a bimodal therapy, consisting of the administration of highly radiation-absorbing substances into the tumor area and localized regional irradiation with orthovoltage x-rays. Irradiation can be performed by a modified computed tomography (CT) unit equipped with an additional x-ray optical module which converts the polychromatic, fan-shaped CT beam into a monochromatized and focused beam for energy-tuned photoelectric-enhanced radiotherapy. A dedicated x-ray optical module designed for spatial collimation, focusing, and monochromatization was mounted at the exit of the x-ray tube of a clinical CT unit. Spectrally resolved measurements of the resulting beam were performed using an energy-dispersive detection system calibrated by synchrotron radiation. The spatial photon fluence was determined by film dosimetry. Depth-dose measurements were performed and compared to the polychromatic CT and a therapeutic 6 MV beam. The spatial dose distribution in phantoms using a rotating radiation source (quasi-monochromatic CT and 6 MV, respectively) was investigated by gel dosimetry. The photoelectric dose enhancement for an iodine fraction of 1% in tissue was calculated and verified experimentally. The x-ray optical module selectively filters the energy of the tungsten Kα emission line with an FWHM of 5 keV. The relative photon fluence distribution demonstrates the focusing characteristic of the x-ray optical module. A beam width of about 3 mm was determined at the isocenter of the CT gantry. The depth-dose measurements resulted in a half-depth value of approximately 36 mm for the CT beams (quasi-monochromatic, polychromatic) compared to 154 mm for the 6 MV beam. The rotation of the radiation source leads to a steep dose gradient at the center of rotation; the gel dosimetry yields an entrance-to-peak dose ratio of 1:10.8 for the quasi-monochromatic CT and 1:37.3 for a 6 MV beam of the same size. The photoelectric dose enhancement factor

Photoelectric-enhanced radiation therapy with quasi-monochromatic computed tomography

Energy Technology Data Exchange (ETDEWEB)

Jost, Gregor; Mensing, Tristan; Golfier, Sven; Lawaczeck, Ruediger; Pietsch, Hubertus; Huetter, Joachim; Cibik, Levent; Gerlach, Martin; Krumrey, Michael; Fratzscher, Daniel; Arkadiev, Vladimir; Wedell, Reiner; Haschke, Michael; Langhoff, Norbert; Wust, Peter; Luedemann, Lutz [TRG Diagnostic Imaging, Bayer Schering Pharma AG, 13353 Berlin (Germany); Department of Radiotherapy, Charite Medical Centre, 13353 Berlin (Germany); TRG Diagnostic Imaging, Bayer Schering Pharma AG, 13353 Berlin (Germany); Physikalisch-Technische Bundesanstalt, 10587 Berlin (Germany); Institute of Applied Photonics e.V., 12489 Berlin (Germany); Institute for Scientific Instruments GmbH, 12489 Berlin (Germany); Department of Radiotherapy, Charite Medical Centre, 13353 Berlin (Germany)

2009-06-15

Photoelectric-enhanced radiation therapy is a bimodal therapy, consisting of the administration of highly radiation-absorbing substances into the tumor area and localized regional irradiation with orthovoltage x-rays. Irradiation can be performed by a modified computed tomography (CT) unit equipped with an additional x-ray optical module which converts the polychromatic, fan-shaped CT beam into a monochromatized and focused beam for energy-tuned photoelectric-enhanced radiotherapy. A dedicated x-ray optical module designed for spatial collimation, focusing, and monochromatization was mounted at the exit of the x-ray tube of a clinical CT unit. Spectrally resolved measurements of the resulting beam were performed using an energy-dispersive detection system calibrated by synchrotron radiation. The spatial photon fluence was determined by film dosimetry. Depth-dose measurements were performed and compared to the polychromatic CT and a therapeutic 6 MV beam. The spatial dose distribution in phantoms using a rotating radiation source (quasi-monochromatic CT and 6 MV, respectively) was investigated by gel dosimetry. The photoelectric dose enhancement for an iodine fraction of 1% in tissue was calculated and verified experimentally. The x-ray optical module selectively filters the energy of the tungsten K{alpha} emission line with an FWHM of 5 keV. The relative photon fluence distribution demonstrates the focusing characteristic of the x-ray optical module. A beam width of about 3 mm was determined at the isocenter of the CT gantry. The depth-dose measurements resulted in a half-depth value of approximately 36 mm for the CT beams (quasi-monochromatic, polychromatic) compared to 154 mm for the 6 MV beam. The rotation of the radiation source leads to a steep dose gradient at the center of rotation; the gel dosimetry yields an entrance-to-peak dose ratio of 1:10.8 for the quasi-monochromatic CT and 1:37.3 for a 6 MV beam of the same size. The photoelectric dose enhancement

MULTI2D - a computer code for two-dimensional radiation hydrodynamics

Science.gov (United States)

Ramis, R.; Meyer-ter-Vehn, J.; Ramírez, J.

2009-06-01

Simulation of radiation hydrodynamics in two spatial dimensions is developed, having in mind, in particular, target design for indirectly driven inertial confinement energy (IFE) and the interpretation of related experiments. Intense radiation pulses by laser or particle beams heat high-Z target configurations of different geometries and lead to a regime which is optically thick in some regions and optically thin in others. A diffusion description is inadequate in this situation. A new numerical code has been developed which describes hydrodynamics in two spatial dimensions (cylindrical R-Z geometry) and radiation transport along rays in three dimensions with the 4 π solid angle discretized in direction. Matter moves on a non-structured mesh composed of trilateral and quadrilateral elements. Radiation flux of a given direction enters on two (one) sides of a triangle and leaves on the opposite side(s) in proportion to the viewing angles depending on the geometry. This scheme allows to propagate sharply edged beams without ray tracing, though at the price of some lateral diffusion. The algorithm treats correctly both the optically thin and optically thick regimes. A symmetric semi-implicit (SSI) method is used to guarantee numerical stability. Program summaryProgram title: MULTI2D Catalogue identifier: AECV_v1_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AECV_v1_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.html No. of lines in distributed program, including test data, etc.: 151 098 No. of bytes in distributed program, including test data, etc.: 889 622 Distribution format: tar.gz Programming language: C Computer: PC (32 bits architecture) Operating system: Linux/Unix RAM: 2 Mbytes Word size: 32 bits Classification: 19.7 External routines: X-window standard library (libX11.so) and corresponding heading files (X11/*.h) are

Measurements of computed tomography radiation scatter

International Nuclear Information System (INIS)

Van Every, B.; Petty, R.J.

1992-01-01

This paper describes the measurement of scattered radiation from a computed tomography (CT) scanner in a clinical situation and compares the results with those obtained from a CT performance phantom and with data obtained from CT manufacturers. The results are presented as iso-dose contours. There are significant differences between the data obtained and that supplied by manufacturers, both in the shape of the iso-dose contours and in the nominal values. The observed scatter in a clinical situation (for an abdominal scan) varied between 3% and 430% of the manufacturers' stated values, with a marked reduction in scatter noted a the head and feet of the patient. These differences appear to be due to the fact that manufacturers use CT phantoms to obtain scatter data and these phantoms do not provide the same scatter absorption geometry as patients. CT scatter was observed to increase as scan field size and slice thickness increased, whilst there was little change in scatter with changes in gantry tilt and table slew. Using the iso-dose contours, the orientation of the CT scanner can be optimised with regard to the location and shielding requirements of doors and windows. Additionally, the positioning of staff who must remain in the room during scanning can be optimised to minimise their exposure. It is estimated that the data presented allows for realistic radiation protection assessments to be made. 13 refs., 5 tabs., 6 figs

Histomorphometric quantification of human pathological bones from synchrotron radiation 3D computed microtomography

International Nuclear Information System (INIS)

Nogueira, Liebert P.; Braz, Delson

2011-01-01

Conventional bone histomorphometry is an important method for quantitative evaluation of bone microstructure. X-ray computed microtomography is a noninvasive technique, which can be used to evaluate histomorphometric indices in trabecular bones (BV/TV, BS/BV, Tb.N, Tb.Th, Tb.Sp). In this technique, the output 3D images are used to quantify the whole sample, differently from the conventional one, in which the quantification is performed in 2D slices and extrapolated for 3D case. In this work, histomorphometric quantification using synchrotron 3D X-ray computed microtomography was performed to quantify pathological samples of human bone. Samples of human bones were cut into small blocks (8 mm x 8 mm x 10 mm) with a precision saw and then imaged. The computed microtomographies were obtained at SYRMEP (Synchrotron Radiation for MEdical Physics) beamline, at ELETTRA synchrotron radiation facility (Italy). The obtained 3D images yielded excellent resolution and details of intra-trabecular bone structures, including marrow present inside trabeculae. Histomorphometric quantification was compared to literature as well. (author)

10th International Conference on Computer Simulation of Radiation Effects in Solids - COSIRES 2010. Abstracts and Programme

International Nuclear Information System (INIS)

2010-01-01

COSIRES 2010 is the 10 th International Conference on Computer Simulation of Radiation Effects in Solids. This series of conferences addresses the development and application of advanced computer modeling techniques to the study of phenomena taking place during interaction of energetic particles and clusters (from several eV to some MeV) with solids. Due to the continuous development of new theoretical methodologies and permanent increase of computer power this research field is growing fast. The application of computer simulations leads to a better understanding of basic microscopic processes taking place during and after irradiation. Fundamental understanding of such processes is often not accessible by experimental methods since they occur on very small time and length scales. However, computer simulation techniques are not only used for investigations of basic phenomena but also increasingly applied in the development of modern industrial technologies. Conference topics include, but are not limited to: I) Computer modeling of following phenomena: · Sputtering; · Formation and evolution of radiation defects in materials; · Radiation responses of structural materials important for nuclear and fusion industry; · Irradiation-induced evolution of surface topography and ripple formation; · Ion beam synthesis of thin films and nanostructures; · Ion-, electron and photon-induced physical and chemical effects at surfaces, interfaces and nanostructures; · Irradiation-induced charge redistribution, electron excitation and electron-phonon interactions II) Development of new computer modeling protocols and interatomic potentials for investigation of radiation effects. The conference follows previous meetings that were held in Berlin/Germany (1992), Santa Barbara/USA (1994), Guildford/UK (1996), Okayama/Japan (1998), State College/USA (2000), Dresden/Germany (2002), Helsinki/Finland (2004), Richland/USA (2006) and finally in Beijing/China (2008). Current meeting is

10th International Conference on Computer Simulation of Radiation Effects in Solids - COSIRES 2010. Abstracts and Programme

Energy Technology Data Exchange (ETDEWEB)

NONE

2010-07-01

COSIRES 2010 is the 10{sup th} International Conference on Computer Simulation of Radiation Effects in Solids. This series of conferences addresses the development and application of advanced computer modeling techniques to the study of phenomena taking place during interaction of energetic particles and clusters (from several eV to some MeV) with solids. Due to the continuous development of new theoretical methodologies and permanent increase of computer power this research field is growing fast. The application of computer simulations leads to a better understanding of basic microscopic processes taking place during and after irradiation. Fundamental understanding of such processes is often not accessible by experimental methods since they occur on very small time and length scales. However, computer simulation techniques are not only used for investigations of basic phenomena but also increasingly applied in the development of modern industrial technologies. Conference topics include, but are not limited to: I) Computer modeling of following phenomena: {center_dot} Sputtering; {center_dot} Formation and evolution of radiation defects in materials; {center_dot} Radiation responses of structural materials important for nuclear and fusion industry; {center_dot} Irradiation-induced evolution of surface topography and ripple formation; {center_dot} Ion beam synthesis of thin films and nanostructures; {center_dot} Ion-, electron and photon-induced physical and chemical effects at surfaces, interfaces and nanostructures; {center_dot} Irradiation-induced charge redistribution, electron excitation and electron-phonon interactions II) Development of new computer modeling protocols and interatomic potentials for investigation of radiation effects. The conference follows previous meetings that were held in Berlin/Germany (1992), Santa Barbara/USA (1994), Guildford/UK (1996), Okayama/Japan (1998), State College/USA (2000), Dresden/Germany (2002), Helsinki/Finland (2004

Evaluation of the computer code system RADHEAT-V4 by analysing benchmark problems on radiation shielding

International Nuclear Information System (INIS)

Sakamoto, Yukio; Naito, Yoshitaka

1990-11-01

A computer code system RADHEAT-V4 has been developed for safety evaluation on radiation shielding of nuclear fuel facilities. To evaluate the performance of the code system, 18 benchmark problem were selected and analysed. Evaluated radiations are neutron and gamma-ray. Benchmark problems consist of penetration, streaming and skyshine. The computed results show more accurate than those by the Sn codes ANISN and DOT3.5 or the Monte Carlo code MORSE. Big core memory and many times I/O are, however, required for RADHEAT-V4. (author)

Two-parametric model of electron beam in computational dosimetry for radiation processing

International Nuclear Information System (INIS)

Lazurik, V.M.; Lazurik, V.T.; Popov, G.; Zimek, Z.

2016-01-01

Computer simulation of irradiation process of various materials with electron beam (EB) can be applied to correct and control the performances of radiation processing installations. Electron beam energy measurements methods are described in the international standards. The obtained results of measurements can be extended by implementation computational dosimetry. Authors have developed the computational method for determination of EB energy on the base of two-parametric fitting of semi-empirical model for the depth dose distribution initiated by mono-energetic electron beam. The analysis of number experiments show that described method can effectively consider random displacements arising from the use of aluminum wedge with a continuous strip of dosimetric film and minimize the magnitude uncertainty value of the electron energy evaluation, calculated from the experimental data. Two-parametric fitting method is proposed for determination of the electron beam model parameters. These model parameters are as follow: E 0 – energy mono-energetic and mono-directional electron source, X 0 – the thickness of the aluminum layer, located in front of irradiated object. That allows obtain baseline data related to the characteristic of the electron beam, which can be later on applied for computer modeling of the irradiation process. Model parameters which are defined in the international standards (like E p – the most probably energy and R p – practical range) can be linked with characteristics of two-parametric model (E 0 , X 0 ), which allows to simulate the electron irradiation process. The obtained data from semi-empirical model were checked together with the set of experimental results. The proposed two-parametric model for electron beam energy evaluation and estimation of accuracy for computational dosimetry methods on the base of developed model are discussed. - Highlights: • Experimental and computational methods of electron energy evaluation. • Development

Tapping of Love waves in an isotropic surface waveguide by surface-to-bulk wave transduction.

Science.gov (United States)

Tuan, H.-S.; Chang, C.-P.

1972-01-01

A theoretical study of tapping a Love wave in an isotropic microacoustic surface waveguide is given. The surface Love wave is tapped by partial transduction into a bulk wave at a discontinuity. It is shown that, by careful design of the discontinuity, the converted bulk wave power and the radiation pattern may be controlled. General formulas are derived for the calculation of these important characteristics from a relatively general surface contour deformation.

The UF family of hybrid phantoms of the developing human fetus for computational radiation dosimetry

Energy Technology Data Exchange (ETDEWEB)

Maynard, Matthew R; Geyer, John W; Bolch, Wesley [Department of Nuclear and Radiological Engineering, University of Florida, Gainesville, FL (United States); Aris, John P [Department of Anatomy and Cell Biology, University of Florida, Gainesville, FL (United States); Shifrin, Roger Y, E-mail: wbolch@ufl.edu [Department of Radiology, University of Florida, Gainesville, FL (United States)

2011-08-07

Historically, the development of computational phantoms for radiation dosimetry has primarily been directed at capturing and representing adult and pediatric anatomy, with less emphasis devoted to models of the human fetus. As concern grows over possible radiation-induced cancers from medical and non-medical exposures of the pregnant female, the need to better quantify fetal radiation doses, particularly at the organ-level, also increases. Studies such as the European Union's SOLO (Epidemiological Studies of Exposed Southern Urals Populations) hope to improve our understanding of cancer risks following chronic in utero radiation exposure. For projects such as SOLO, currently available fetal anatomic models do not provide sufficient anatomical detail for organ-level dose assessment. To address this need, two fetal hybrid computational phantoms were constructed using high-quality magnetic resonance imaging and computed tomography image sets obtained for two well-preserved fetal specimens aged 11.5 and 21 weeks post-conception. Individual soft tissue organs, bone sites and outer body contours were segmented from these images using 3D-DOCTOR(TM) and then imported to the 3D modeling software package Rhinoceros(TM) for further modeling and conversion of soft tissue organs, certain bone sites and outer body contours to deformable non-uniform rational B-spline surfaces. The two specimen-specific phantoms, along with a modified version of the 38 week UF hybrid newborn phantom, comprised a set of base phantoms from which a series of hybrid computational phantoms was derived for fetal ages 8, 10, 15, 20, 25, 30, 35 and 38 weeks post-conception. The methodology used to construct the series of phantoms accounted for the following age-dependent parameters: (1) variations in skeletal size and proportion, (2) bone-dependent variations in relative levels of bone growth, (3) variations in individual organ masses and total fetal masses and (4) statistical percentile variations

Development of application program and building database to increase facilities for using the radiation effect assessment computer codes

International Nuclear Information System (INIS)

Hyun Seok Ko; Young Min Kim; Suk-Hoon Kim; Dong Hoon Shin; Chang-Sun Kang

2005-01-01

The current radiation effect assessment system is required the skillful technique about the application for various code and high level of special knowledge classified by field. Therefore, as a matter of fact, it is very difficult for the radiation users' who don't have enough special knowledge to assess or recognize the radiation effect properly. For this, we already have developed the five Computer codes(windows-based), that is the radiation effect assessment system, in radiation utilizing field including the nuclear power generation. It needs the computer program that non-specialist can use the five computer codes to have already developed with ease. So, we embodied the A.I-based specialist system that can infer the assessment system by itself, according to the characteristic of given problem. The specialist program can guide users, search data, inquire of administrator directly. Conceptually, with circumstance which user to apply the five computer code may encounter actually, we embodied to consider aspects as follows. First, the accessibility of concept and data to need must be improved. Second, the acquirement of reference theory and use of corresponding computer code must be easy. Third, Q and A function needed for solution of user's question out of consideration previously. Finally, the database must be renewed continuously. Actually, to express this necessity, we develop the client program to organize reference data, to build the access methodology(query) about organized data, to load the visible expression function of searched data. And It is embodied the instruction method(effective theory acquirement procedure and methodology) to acquire the theory referring the five computer codes. It is developed the data structure access program(DBMS) to renew continuously data with ease. For Q and A function, it is embodied the Q and A board within client program because the user of client program can search the content of question and answer. (authors)

Surface and Bulk Nanostructuring of Insulators by Ultrashort Laser Pulses

Science.gov (United States)

2017-04-05

non perturbative effects leading to HHG. 15. SUBJECT TERMS Nanostructuring of bulk insulators, sub-picosecond electronic and structural events , photo...time, the charge density oscillations follow the time periodicity of the incident radiation. These transient charge oscillations are exclusively due...As in section II photoexcitation and the dielectric response of laser-irradiated diamond are treated in independent particle approximation based on the

Simulation and analysis of microwave heating while joining bulk ...

African Journals Online (AJOL)

ATHARVA

Processing of bulk metallic materials using microwave energy is challenging. ... The distributed power and heat source were computed in a stationary, .... the heat transfer equation is used in order to get the temperature distributions and other system properties. ... equation (2) to obtain the distribution of the E and H fields.

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

International Nuclear Information System (INIS)

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

2016-01-01

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

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

Energy Technology Data Exchange (ETDEWEB)

Šafránková, J.; Němeček, Z.; Němec, F.; Přech, L. [Charles University, Faculty of Mathematics and Physics, V Holešovičkách 2, 180 00 Prague 8 (Czech Republic); Chen, C. H. K. [Department of Physics, Imperial College London, London SW7 2AZ (United Kingdom); Zastenker, G. N., E-mail: jana.safrankova@mff.cuni.cz [Space Research Institute of Russian Academy of Sciences, Moscow, Russia, Profsoyuznaya ul. 84/32, Moscow 117997 (Russian Federation)

2016-07-10

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

The bulk modulus of cubic spinel selenides: an experimental and theoretical study

DEFF Research Database (Denmark)

Waskowska, A.; Gerward, Leif; Olsen, J.S.

2009-01-01

It is argued that mainly the selenium sublattice determines the overall compressibility of the cubic spinel selenides, AB2Se4, and that the bulk modulus for these compounds is about 100GPa. The hypothesis is supported by experiments using high-pressure X-ray diffraction and synchrotron radiation...

Advanced Computational Methods for Thermal Radiative Heat Transfer

Energy Technology Data Exchange (ETDEWEB)

Tencer, John; Carlberg, Kevin Thomas; Larsen, Marvin E.; Hogan, Roy E.,

2016-10-01

Participating media radiation (PMR) in weapon safety calculations for abnormal thermal environments are too costly to do routinely. This cost may be s ubstantially reduced by applying reduced order modeling (ROM) techniques. The application of ROM to PMR is a new and unique approach for this class of problems. This approach was investigated by the authors and shown to provide significant reductions in the computational expense associated with typical PMR simulations. Once this technology is migrated into production heat transfer analysis codes this capability will enable the routine use of PMR heat transfer in higher - fidelity simulations of weapon resp onse in fire environments.

Utilization of a computer using programless language for radiation protection management

International Nuclear Information System (INIS)

Masuko, Syozi; Kasahara, Shigeru

1985-01-01

The practice of radiation management is different for each laboratory both in point of view and in the form of recording. Therefore, the computer program for the radiation management, especially for the management of radioisotopes is required to meet many amendments. In this standpoint, we have developed a ''programless language'' or ''programless software'' and have used in our work for several years. As the result of our experience, we have found that the programless language is quite satisfactory for the management of radioisotopes and that it has an advantage in some aspects over conventional programs. It is thought that this ''programless language'' is effective not only for our own works, but also applicable to other radioisotope laboratories. (author)

An object-oriented bulk synchronous parallel library for multicore programming

NARCIS (Netherlands)

Yzelman, A.N.; Bisseling, R.H.

2012-01-01

We show that the bulk synchronous parallel (BSP) model, originally designed for distributed-memory systems, is also applicable for shared-memory multicore systems and, furthermore, that BSP libraries are useful in scientific computing on these systems. A proof-of-concept MulticoreBSP library has

The computer system for registration and dosimetric control of inhabitants, cosmonauts and pilots from the different radiation sources

International Nuclear Information System (INIS)

Lebedev, L.A.; Koniaev, S.V.; Mikheenko, S.G.; Rusin, S.V.; Sidorin, V.P.

1996-01-01

Cosmonauts, pilots and inhabitants living near the nuclear power plants or nuclear facilities are particular group of risk. To estimate the radiation risk for this limited part of population the Computer System was developed. The main purpose of this System is registration, account, storage, processing, analysis, forecasting and control both doses and radiation risks for each person. Both experimental and calculated data are used in the Computer System. The experimental data are used in case of estimation of doses received by cosmonauts during space flight and by pilots during the flight in atmosphere. The System allows to calculate the doses for each person from any type of medical procedures including the X-ray diagnostic examinations and radioisotopic diagnostics. The Computer System also allows to calculate the radiation exposure of inhabitants living near nuclear facilities both in case of normal exploitation and different kind of accidents. The annual dose distribution from different types of radiation sources are given. It was shown that doses from medical irradiation are comparable or sometime higher than the doses from space flight, air flight or nuclear accident. (author)

Study and characterization of III-V semiconductor materials for applications in ionizing radiation detection

International Nuclear Information System (INIS)

Moulin, H.

1989-11-01

The photoconduction in the bulk of the gallium arsenide (GaAs) and of the indium phosphide doped with iron (InP:Fe) is investigated. These semiconductor materials are to be applied in X rays detection. The photoconduction theory and the physical characteristics of those materials are reviewed. The computer simulation models for studying the photoconductor responses to the radiation pulses are described. The experimental results are discussed. They include the following aspects: the characterization of the GaAs and InP:Fe, in the obscurity, as a function of the polarized electric field and of the neutrons dose; the characterization under X ray. Continuous X rays and pulsed synchrotron radiation are applied [fr

Computer codes for tasks in the fields of isotope and radiation research

International Nuclear Information System (INIS)

Friedrich, K.; Gebhardt, O.

1978-11-01

Concise descriptions of computer codes developed for solving problems in the fields of isotope and radiation research at the Zentralinstitut fuer Isotopen- und Strahlenforschung (ZfI) are compiled. In part two the structure of the ZfI program library MABIF is outlined and a complete list of all codes available is given

Bulk oil clauses

International Nuclear Information System (INIS)

Gough, N.

1993-01-01

The Institute Bulk Oil Clauses produced by the London market and the American SP-13c Clauses are examined in detail in this article. The duration and perils covered are discussed, and exclusions, adjustment clause 15 of the Institute Bulk Oil Clauses, Institute War Clauses (Cargo), and Institute Strikes Clauses (Bulk Oil) are outlined. (UK)

Effect of strong disorder on three-dimensional chiral topological insulators: Phase diagrams, maps of the bulk invariant, and existence of topological extended bulk states

Science.gov (United States)

Song, Juntao; Fine, Carolyn; Prodan, Emil

2014-11-01

The effect of strong disorder on chiral-symmetric three-dimensional lattice models is investigated via analytical and numerical methods. The phase diagrams of the models are computed using the noncommutative winding number, as functions of disorder strength and model's parameters. The localized/delocalized characteristic of the quantum states is probed with level statistics analysis. Our study reconfirms the accurate quantization of the noncommutative winding number in the presence of strong disorder, and its effectiveness as a numerical tool. Extended bulk states are detected above and below the Fermi level, which are observed to undergo the so-called "levitation and pair annihilation" process when the system is driven through a topological transition. This suggests that the bulk invariant is carried by these extended states, in stark contrast with the one-dimensional case where the extended states are completely absent and the bulk invariant is carried by the localized states.

Estimation of bulk transfer coefficient for latent heat flux (Ce)

Digital Repository Service at National Institute of Oceanography (India)

Sadhuram, Y.

The bulk transfer coefficient for latent heat flux (Ce) has been estimated over the Arabian Sea from the moisture budget during the pre-monsoon season of 1988. The computations have been made over two regions (A: 0-8 degrees N: 60-68 degrees E: B: 0...

Toward a web-based real-time radiation treatment planning system in a cloud computing environment.

Science.gov (United States)

Na, Yong Hum; Suh, Tae-Suk; Kapp, Daniel S; Xing, Lei

2013-09-21

To exploit the potential dosimetric advantages of intensity modulated radiation therapy (IMRT) and volumetric modulated arc therapy (VMAT), an in-depth approach is required to provide efficient computing methods. This needs to incorporate clinically related organ specific constraints, Monte Carlo (MC) dose calculations, and large-scale plan optimization. This paper describes our first steps toward a web-based real-time radiation treatment planning system in a cloud computing environment (CCE). The Amazon Elastic Compute Cloud (EC2) with a master node (named m2.xlarge containing 17.1 GB of memory, two virtual cores with 3.25 EC2 Compute Units each, 420 GB of instance storage, 64-bit platform) is used as the backbone of cloud computing for dose calculation and plan optimization. The master node is able to scale the workers on an 'on-demand' basis. MC dose calculation is employed to generate accurate beamlet dose kernels by parallel tasks. The intensity modulation optimization uses total-variation regularization (TVR) and generates piecewise constant fluence maps for each initial beam direction in a distributed manner over the CCE. The optimized fluence maps are segmented into deliverable apertures. The shape of each aperture is iteratively rectified to be a sequence of arcs using the manufacture's constraints. The output plan file from the EC2 is sent to the simple storage service. Three de-identified clinical cancer treatment plans have been studied for evaluating the performance of the new planning platform with 6 MV flattening filter free beams (40 × 40 cm(2)) from the Varian TrueBeam(TM) STx linear accelerator. A CCE leads to speed-ups of up to 14-fold for both dose kernel calculations and plan optimizations in the head and neck, lung, and prostate cancer cases considered in this study. The proposed system relies on a CCE that is able to provide an infrastructure for parallel and distributed computing. The resultant plans from the cloud computing are

Toward a web-based real-time radiation treatment planning system in a cloud computing environment

International Nuclear Information System (INIS)

Na, Yong Hum; Kapp, Daniel S; Xing, Lei; Suh, Tae-Suk

2013-01-01

To exploit the potential dosimetric advantages of intensity modulated radiation therapy (IMRT) and volumetric modulated arc therapy (VMAT), an in-depth approach is required to provide efficient computing methods. This needs to incorporate clinically related organ specific constraints, Monte Carlo (MC) dose calculations, and large-scale plan optimization. This paper describes our first steps toward a web-based real-time radiation treatment planning system in a cloud computing environment (CCE). The Amazon Elastic Compute Cloud (EC2) with a master node (named m2.xlarge containing 17.1 GB of memory, two virtual cores with 3.25 EC2 Compute Units each, 420 GB of instance storage, 64-bit platform) is used as the backbone of cloud computing for dose calculation and plan optimization. The master node is able to scale the workers on an ‘on-demand’ basis. MC dose calculation is employed to generate accurate beamlet dose kernels by parallel tasks. The intensity modulation optimization uses total-variation regularization (TVR) and generates piecewise constant fluence maps for each initial beam direction in a distributed manner over the CCE. The optimized fluence maps are segmented into deliverable apertures. The shape of each aperture is iteratively rectified to be a sequence of arcs using the manufacture’s constraints. The output plan file from the EC2 is sent to the simple storage service. Three de-identified clinical cancer treatment plans have been studied for evaluating the performance of the new planning platform with 6 MV flattening filter free beams (40 × 40 cm 2 ) from the Varian TrueBeam TM STx linear accelerator. A CCE leads to speed-ups of up to 14-fold for both dose kernel calculations and plan optimizations in the head and neck, lung, and prostate cancer cases considered in this study. The proposed system relies on a CCE that is able to provide an infrastructure for parallel and distributed computing. The resultant plans from the cloud computing are

Bulk-Fill Resin Composites

DEFF Research Database (Denmark)

Benetti, Ana Raquel; Havndrup-Pedersen, Cæcilie; Honoré, Daniel

2015-01-01

the restorative procedure. The aim of this study, therefore, was to compare the depth of cure, polymerization contraction, and gap formation in bulk-fill resin composites with those of a conventional resin composite. To achieve this, the depth of cure was assessed in accordance with the International Organization...... for Standardization 4049 standard, and the polymerization contraction was determined using the bonded-disc method. The gap formation was measured at the dentin margin of Class II cavities. Five bulk-fill resin composites were investigated: two high-viscosity (Tetric EvoCeram Bulk Fill, SonicFill) and three low......-viscosity (x-tra base, Venus Bulk Fill, SDR) materials. Compared with the conventional resin composite, the high-viscosity bulk-fill materials exhibited only a small increase (but significant for Tetric EvoCeram Bulk Fill) in depth of cure and polymerization contraction, whereas the low-viscosity bulk...

Ductile crack initiation and propagation assessed via in situ synchrotron radiation-computed laminography

International Nuclear Information System (INIS)

Morgeneyer, T.F.; Helfen, L.; Sinclair, I.; Proudhon, H.; Xu, F.; Baumbach, T.

2011-01-01

Ductile crack initiation and propagation within a naturally aged aluminium alloy sheet has been observed in situ via synchrotron radiation-computed laminography, a technique specifically adapted to three-dimensional imaging of thin objects that are laterally extended. Voids and intermetallic particles, and their subsequent evolution during ductile crack extension at different associated levels of stress triaxiality, were clearly observed within fracture coupons of a reasonable engineering length-scale, overcoming the conventional sample size limitation of computed tomography at high resolutions.

Computation of the radiation Q of dielectric-loaded electrically small antennas in integral equation formulations

DEFF Research Database (Denmark)

Kim, Oleksiy S.

2016-01-01

A new technique for estimating the impedance frequency bandwidth of electrically small antennas loaded with magneto-dielectric material from a single-frequency simulation in a surface integral equation solver is presented. The estimate is based on the inverse of the radiation Q computed using newly...... derived expressions for the stored energy and the radiated power of arbitrary coupled electric and magnetic currents in free space....

Bulk analysis using nuclear techniques

International Nuclear Information System (INIS)

Borsaru, M.; Holmes, R.J.; Mathew, P.J.

1983-01-01

Bulk analysis techniques developed for the mining industry are reviewed. Using penetrating neutron and #betta#-radiations, measurements are obtained directly from a large volume of sample (3-30 kg) #betta#-techniques were used to determine the grade of iron ore and to detect shale on conveyor belts. Thermal neutron irradiation was developed for the simultaneous determination of iron and aluminium in iron ore on a conveyor belt. Thermal-neutron activation analysis includes the determination of alumina in bauxite, and manganese and alumina in manganese ore. Fast neutron activation analysis is used to determine silicon in iron ores, and alumina and silica in bauxite. Fast and thermal neutron activation has been used to determine the soil in shredded sugar cane. (U.K.)

A k-distribution-based radiation code and its computational optimization for an atmospheric general circulation model

International Nuclear Information System (INIS)

Sekiguchi, Miho; Nakajima, Teruyuki

2008-01-01

The gas absorption process scheme in the broadband radiative transfer code 'mstrn8', which is used to calculate atmospheric radiative transfer efficiently in a general circulation model, is improved. Three major improvements are made. The first is an update of the database of line absorption parameters and the continuum absorption model. The second is a change to the definition of the selection rule for gas absorption used to choose which absorption bands to include. The last is an upgrade of the optimization method used to decrease the number of quadrature points used for numerical integration in the correlated k-distribution approach, thereby realizing higher computational efficiency without losing accuracy. The new radiation package termed 'mstrnX' computes radiation fluxes and heating rates with errors less than 0.6 W/m 2 and 0.3 K/day, respectively, through the troposphere and the lower stratosphere for any standard AFGL atmospheres. A serious cold bias problem of an atmospheric general circulation model using the ancestor code 'mstrn8' is almost solved by the upgrade to 'mstrnX'

Reliability of real-time computing with radiation data feedback at accidental release

International Nuclear Information System (INIS)

Deme, S.; Feher, I.; Lang, E.

1990-01-01

At the first workshop in 1985 we reported on the real-time dose computing method used at the Paks Nuclear Power Plant and on the telemetric system developed for the normalization of the computed data. At present, the computing method normalized for the telemetric data represents the primary information for deciding on any necessary counter measures in case of a nuclear reactor accident. In this connection we analyzed the reliability of the results obtained in this manner. The points of the analysis were: how the results are influenced by the choice of certain parameters that cannot be determined by direct methods and how the improperly chosen diffusion parameters would distort the determination of environmental radiation parameters normalized on the basis of the measurements ( 131 I activity concentration, gamma dose rate) at points lying at a given distance from the measuring stations. A further source of errors may be that, when determining the level of gamma radiation, the radionuclide doses in the cloud and on the ground surface are measured together by the environmental monitoring stations, whereas these doses appear separately in the computations. At the Paks NPP it is the time integral of the aiborne activity concentration of vapour form 131 I which is determined. This quantity includes neither the other physical and chemical forms of 131 I nor the other isotopes of radioiodine. We gave numerical examples for the uncertainties due to the above factors. As a result, we arrived at the conclusions that there is a need to decide on accident-related measures based on the computing method that the dose uncertainties may reach one order of magnitude for points lying far from the monitoring stations. Different measures are discussed to make the uncertainties significantly lower

Developmental morphology of cover crop species exhibit contrasting behaviour to changes in soil bulk density, revealed by X-ray computed tomography.

Science.gov (United States)

Burr-Hersey, Jasmine E; Mooney, Sacha J; Bengough, A Glyn; Mairhofer, Stefan; Ritz, Karl

2017-01-01

Plant roots growing through soil typically encounter considerable structural heterogeneity, and local variations in soil dry bulk density. The way the in situ architecture of root systems of different species respond to such heterogeneity is poorly understood due to challenges in visualising roots growing in soil. The objective of this study was to visualise and quantify the impact of abrupt changes in soil bulk density on the roots of three cover crop species with contrasting inherent root morphologies, viz. tillage radish (Raphanus sativus), vetch (Vicia sativa) and black oat (Avena strigosa). The species were grown in soil columns containing a two-layer compaction treatment featuring a 1.2 g cm-3 (uncompacted) zone overlaying a 1.4 g cm-3 (compacted) zone. Three-dimensional visualisations of the root architecture were generated via X-ray computed tomography, and an automated root-segmentation imaging algorithm. Three classes of behaviour were manifest as a result of roots encountering the compacted interface, directly related to the species. For radish, there was switch from a single tap-root to multiple perpendicular roots which penetrated the compacted zone, whilst for vetch primary roots were diverted more horizontally with limited lateral growth at less acute angles. Black oat roots penetrated the compacted zone with no apparent deviation. Smaller root volume, surface area and lateral growth were consistently observed in the compacted zone in comparison to the uncompacted zone across all species. The rapid transition in soil bulk density had a large effect on root morphology that differed greatly between species, with major implications for how these cover crops will modify and interact with soil structure.

Computational Tools and Approaches for Design and Control of Coating and Composite Color, Appearance, and Electromagnetic Signature

Directory of Open Access Journals (Sweden)

Erik D. Sapper

2013-04-01

Full Text Available The transport behavior of electromagnetic radiation through a polymeric coating or composite is the basis for the material color, appearance, and overall electromagnetic signature. As multifunctional materials become more advanced and next generation in-service applications become more demanding, a need for predictive design of electromagnetic signature is desired. This paper presents various components developed and used in a computational suite for the study and design of electromagnetic radiation transport properties in polymeric coatings and composites. Focus is given to the treatment of the forward or direct scattering problem on surfaces and in bulk matrices of polymeric materials. The suite consists of surface and bulk light scattering simulation modules that may be coupled together to produce a multiscale model for predicting the electromagnetic signature of various material systems. Geometric optics ray tracing is used to predict surface scattering behavior of realistically rough surfaces, while a coupled ray tracing-finite element approach is used to predict bulk scattering behavior of material matrices consisting of microscale and nanoscale fillers, pigments, fibers, air voids, and other inclusions. Extension of the suite to color change and appearance metamerism is addressed, as well as the differences between discrete versus statistical material modeling.

Pentacene–fullerene bulk-heterojunction solar cell: A computational study

Energy Technology Data Exchange (ETDEWEB)

Pramanik, Anup [Department of Chemistry, Visva-Bharati University, Santiniketan 731235 (India); Sarkar, Sunandan [Department of Chemistry, Visva-Bharati University, Santiniketan 731235 (India); Dept. of Physical Chemistry, Palacký University, Olomouc (Czech Republic); Pal, Sougata [Department of Chemistry, University of Gour Banga, Malda 732103 (India); Sarkar, Pranab, E-mail: pranab.sarkar@visva-bharati.ac.in [Department of Chemistry, Visva-Bharati University, Santiniketan 731235 (India)

2015-06-12

We perform DFT/TDDFT calculations to study the optoelectronic properties of some pentacene-based organic molecules and their derivatives, which can serve as donor moiety when blended with fullerene acceptors in the bulk-heterojunction solar cell model. We are motivated by a recent experiment in which an unoptimized device was shown to have a good photovoltaic performance and we aim to further improve the efficiency of this device. We try to optimize the photovoltaic properties on the basis of a quantum-mechanical calculation of the frontier energy levels and of the absorption properties of individual molecules and of the molecule–fullerine composite. - Highlights: • Optoelectronic properties of pentacene–fullerene nanocomposites are presented. • Photovoltaic properties of the nanocomposites are predicted. • DFT/TDDFT results are in well agreement with available experimental results. • Calculated results give a direction for optimizing device performance.

Computed Tomography Number Changes Observed During Computed Tomography–Guided Radiation Therapy for Head and Neck Cancer

International Nuclear Information System (INIS)

Feng, Mei; Yang, Cungeng; Chen, Xiaojian; Xu, Shouping; Moraru, Ion; Lang, Jinyi; Schultz, Christopher; Li, X. Allen

2015-01-01

Purpose: To investigate CT number (CTN) changes in gross tumor volume (GTV) and organ at risk (OAR) according to daily diagnostic-quality CT acquired during CT-guided intensity modulated radiation therapy for head and neck cancer (HNC) patients. Methods and Materials: Computed tomography scans acquired using a CT-on-rails during daily CT-guided intensity modulated radiation therapy for 15 patients with stage II to IVa squamous cell carcinoma of the head and neck were analyzed. The GTV, parotid glands, spinal cord, and nonspecified tissue were generated on each selected daily CT. The changes in CTN distributions and the mean and mode values were collected. Pearson analysis was used to assess the correlation between the CTN change, organ volume reduction, and delivered radiation dose. Results: Volume and CTN changes for GTV and parotid glands can be observed during radiation therapy delivery for HNC. The mean (±SD) CTNs in GTV and ipsi- and contralateral parotid glands were reduced by 6 ± 10, 8 ± 7, and 11 ± 10 Hounsfield units, respectively, for all patients studied. The mean CTN changes in both spinal cord and nonspecified tissue were almost invisible (<2 Hounsfield units). For 2 patients studied, the absolute mean CTN changes in GTV and parotid glands were strongly correlated with the dose delivered (P<.001 and P<.05, respectively). For the correlation between CTN reductions and delivered isodose bins for parotid glands, the Pearson coefficient varied from −0.98 (P<.001) in regions with low-dose bins to 0.96 (P<.001) in high-dose bins and were patient specific. Conclusions: The CTN can be reduced in tumor and parotid glands during the course of radiation therapy for HNC. There was a fair correlation between CTN reduction and radiation doses for a subset of patients, whereas the correlation between CTN reductions and volume reductions in GTV and parotid glands were weak. More studies are needed to understand the mechanism for the radiation-induced CTN changes

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

Energy Technology Data Exchange (ETDEWEB)

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.)

The use of symbolic computation in radiative, energy, and neutron transport calculations. Technical report, 15 August 1992--14 August 1994

International Nuclear Information System (INIS)

Frankel, J.I.

1995-01-01

This investigation uses symbolic computation in developing analytical methods and general computational strategies for solving both linear and nonlinear, regular and singular, integral and integro-differential equations which appear in radiative and combined mode energy transport. This technical report summarizes the research conducted during the first nine months of the present investigation. The use of Chebyshev polynomials augmented with symbolic computation has clearly been demonstrated in problems involving radiative (or neutron) transport, and mixed-mode energy transport. Theoretical issues related to convergence, errors, and accuracy have also been pursued. Three manuscripts have resulted from the funded research. These manuscripts have been submitted to archival journals. At the present time, an investigation involving a conductive and radiative medium is underway. The mathematical formulation leads to a system of nonlinear, weakly-singular integral equations involving the unknown temperature and various Legendre moments of the radiative intensity in a participating medium. Some preliminary results are presented illustrating the direction of the proposed research

An efficient method for computing the absorption of solar radiation by water vapor

Science.gov (United States)

Chou, M.-D.; Arking, A.

1981-01-01

Chou and Arking (1980) have developed a fast but accurate method for computing the IR cooling rate due to water vapor. Using a similar approach, the considered investigation develops a method for computing the heating rates due to the absorption of solar radiation by water vapor in the wavelength range from 4 to 8.3 micrometers. The validity of the method is verified by comparison with line-by-line calculations. An outline is provided of an efficient method for transmittance and flux computations based upon actual line parameters. High speed is achieved by employing a one-parameter scaling approximation to convert an inhomogeneous path into an equivalent homogeneous path at suitably chosen reference conditions.

A Scalable GVT Estimation Algorithm for PDES: Using Lower Bound of Event-Bulk-Time

Directory of Open Access Journals (Sweden)

Yong Peng

2015-01-01

Full Text Available Global Virtual Time computation of Parallel Discrete Event Simulation is crucial for conducting fossil collection and detecting the termination of simulation. The triggering condition of GVT computation in typical approaches is generally based on the wall-clock time or logical time intervals. However, the GVT value depends on the timestamps of events rather than the wall-clock time or logical time intervals. Therefore, it is difficult for the existing approaches to select appropriate time intervals to compute the GVT value. In this study, we propose a scalable GVT estimation algorithm based on Lower Bound of Event-Bulk-Time, which triggers the computation of the GVT value according to the number of processed events. In order to calculate the number of transient messages, our algorithm employs Event-Bulk to record the messages sent and received by Logical Processes. To eliminate the performance bottleneck, we adopt an overlapping computation approach to distribute the workload of GVT computation to all worker-threads. We compare our algorithm with the fast asynchronous GVT algorithm using PHOLD benchmark on the shared memory machine. Experimental results indicate that our algorithm has a light overhead and shows higher speedup and accuracy of GVT computation than the fast asynchronous GVT algorithm.

Calculation of radiation losses in cylinder symmetric high pressure discharges by means of a digital computer

International Nuclear Information System (INIS)

Andriessen, F.J.; Boerman, W.; Holtz, I.F.E.M.

1973-08-01

Computer calculations have been made of radiative energy losses in a cylindrically symmetric high pressure discharge. The calculations show that the radiation losses which occur in discharges at pressures of a few atmospheres and central temperatures of about 20000degK when compared with the electrical energy supplied, are only of importance in the neighbourhood of the centre of discharge

Practical application of computer program Panthere for workers' radiation protection

International Nuclear Information System (INIS)

Carlier, Pierre; Michoux, Xavier; Lereculey, Clement

2014-01-01

The civil engineering operations to strengthen the raft of Fessenheim's nuclear plant were carried out by EDF. This technical modification has two principles objectives: 1) to increase the thickness of the reactor pit's concrete and 2) to create a new spreading area for corium (by creating a penetration through the wall of the reactor pit). Behind the complex technical operations two radioprotection issues were studied using the computer program 'PANTHERE': 1) Workers' radiation protection during the execution of the work (because of high dose rates in the reactor pit) and 2) operators' radiation protection after the execution of the work. Results contributed to decrease personal and collective dosimetry of operations and to model and design a biological shield to protect workers during Fessenheim reactor operation. (authors)

Photoelectron spectroscopy bulk and surface electronic structures

CERN Document Server

Suga, Shigemasa

2014-01-01

Photoelectron spectroscopy is now becoming more and more required to investigate electronic structures of various solid materials in the bulk, on surfaces as well as at buried interfaces. The energy resolution was much improved in the last decade down to 1 meV in the low photon energy region. Now this technique is available from a few eV up to 10 keV by use of lasers, electron cyclotron resonance lamps in addition to synchrotron radiation and X-ray tubes. High resolution angle resolved photoelectron spectroscopy (ARPES) is now widely applied to band mapping of materials. It attracts a wide attention from both fundamental science and material engineering. Studies of the dynamics of excited states are feasible by time of flight spectroscopy with fully utilizing the pulse structures of synchrotron radiation as well as lasers including the free electron lasers (FEL). Spin resolved studies also made dramatic progress by using higher efficiency spin detectors and two dimensional spin detectors. Polarization depend...

The application of computer and automatic technology in dose measurement of neutron radiation

International Nuclear Information System (INIS)

Zhou Yu; Li Chenglin; Luo Yisheng; Guo Yong; Chen Di; Xiaojiang

1999-01-01

Generally the dose measurement of neutron radiation requires three electrometers, two bias, three workers in the same time. To improve the accuracy and efficiency of measurement, a Model 6517A electrometer that accommodate Model 6521 scanner cards and a portable computer are used to make up of a automatic measurement system. Corresponding software is developed and used to control it. Because of the application of computer and automatic technology, this system can not only measure dose rate automatically, but also make data's calculating, saving, querying, printing and comparing ease

Procedure and device for the radiometric determination of the quantity, quality and foreign substances in moved bulk materials

International Nuclear Information System (INIS)

Krone, C.; Jentsch, G.; Berger, J.

1987-01-01

This invention has to do with a procedure and device for the simultaneous radiometric determination of quantity, quality and foreign substances in moved bulk materials in particular lignite at one measuring point. The section of the bulk material discharge is transmitted by nuclides for soft and hard gamma radiation in pairs. The pulse rates are registered in pairs by means of detectors and evaluated in real-time operation

Monte Carlo radiation transport: A revolution in science

International Nuclear Information System (INIS)

Hendricks, J.

1993-01-01

When Enrico Fermi, Stan Ulam, Nicholas Metropolis, John von Neuman, and Robert Richtmyer invented the Monte Carlo method fifty years ago, little could they imagine the far-flung consequences, the international applications, and the revolution in science epitomized by their abstract mathematical method. The Monte Carlo method is used in a wide variety of fields to solve exact computational models approximately by statistical sampling. It is an alternative to traditional physics modeling methods which solve approximate computational models exactly by deterministic methods. Modern computers and improved methods, such as variance reduction, have enhanced the method to the point of enabling a true predictive capability in areas such as radiation or particle transport. This predictive capability has contributed to a radical change in the way science is done: design and understanding come from computations built upon experiments rather than being limited to experiments, and the computer codes doing the computations have become the repository for physics knowledge. The MCNP Monte Carlo computer code effort at Los Alamos is an example of this revolution. Physicians unfamiliar with physics details can design cancer treatments using physics buried in the MCNP computer code. Hazardous environments and hypothetical accidents can be explored. Many other fields, from underground oil well exploration to aerospace, from physics research to energy production, from safety to bulk materials processing, benefit from MCNP, the Monte Carlo method, and the revolution in science

Computer aided in-flight radiation scanning

International Nuclear Information System (INIS)

Schmitzer, C.; Kloesch, W.

1989-01-01

The equipment consists of a radiation detecting instrument, a flight prospection probe and a portable PC. It is aimed at detection of ground radiation sources from a flying airplane, e.g. in case of radiation accident. 3 figs

EDISTR: a computer program to obtain a nuclear decay data base for radiation dosimetry

International Nuclear Information System (INIS)

Dillman, L.T.

1980-01-01

This report provides documentation for the computer program EDISTR. EDISTR uses basic radioactive decay data from the Evaluated Nuclear Structure Data File developed and maintained by the Nuclear Data Project at the Oak Ridge National Laboratory as input, and calculates the mean energies and absolute intensities of all principal radiations associated with the radioactive decay of a nuclide. The program is intended to provide a physical data base for internal dosimetry calculations. The principal calculations performed by EDISTR are the determination of (1) the average energy of beta particles in a beta transition, (2) the beta spectrum as function of energy, (3) the energies and intensities of x-rays and Auger electrons generated by radioactive decay processes, (4) the bremsstrahlung spectra accompanying beta decay and monoenergetic Auger and internal conversion electrons, and (5) the radiations accompanying spontaneous fission. This report discusses the theoretical and empirical methods used in EDISTR and also practical aspects of the computer implementation of the theory. Detailed instructions for preparing input data for the computer program are included, along with examples and discussion of the output data generated by EDISTR

Effective temperatures and radiation spectra for a higher-dimensional Schwarzschild-de Sitter black hole

Science.gov (United States)

Kanti, P.; Pappas, T.

2017-07-01

The absence of a true thermodynamical equilibrium for an observer located in the causal area of a Schwarzschild-de Sitter spacetime has repeatedly raised the question of the correct definition of its temperature. In this work, we consider five different temperatures for a higher-dimensional Schwarzschild-de Sitter black hole: the bare T0, the normalized TBH, and three effective ones given in terms of both the black-hole and cosmological horizon temperatures. We find that these five temperatures exhibit similarities but also significant differences in their behavior as the number of extra dimensions and the value of the cosmological constant are varied. We then investigate their effect on the energy emission spectra of Hawking radiation. We demonstrate that the radiation spectra for the normalized temperature TBH—proposed by Bousso and Hawking over twenty years ago—leads to the dominant emission curve, while the other temperatures either support a significant emission rate only in a specific Λ regime or have their emission rates globally suppressed. Finally, we compute the bulk-over-brane emissivity ratio and show that the use of different temperatures may lead to different conclusions regarding the brane or bulk dominance.

Feasibility of dual-energy computed tomography in radiation therapy planning

Science.gov (United States)

Sheen, Heesoon; Shin, Han-Back; Cho, Sungkoo; Cho, Junsang; Han, Youngyih

2017-12-01

In this study, the noise level, effective atomic number ( Z eff), accuracy of the computed tomography (CT) number, and the CT number to the relative electron density EDconversion curve were estimated for virtual monochromatic energy and polychromatic energy. These values were compared to the theoretically predicted values to investigate the feasibility of the use of dual-energy CT in routine radiation therapy planning. The accuracies of the parameters were within the range of acceptability. These results can serve as a stepping stone toward the routine use of dual-energy CT in radiotherapy planning.

Computing radiation dose to reactor pressure vessel and internals

International Nuclear Information System (INIS)

1996-01-01

Within the next twenty years many of the nuclear reactors currently in service will reach their design lifetime. One of the key factors affecting decisions on license extensions will be the ability to confidently predict the integrity of the reactor pressure vessel and core structural components which have been subjected to many years of cumulative radiation exposure. This report gives an overview of the most recent scientific literature and current methodologies for computational dosimetry in the OECD/NEA Member countries. Discussion is extended to consider some related issues of materials science, such as the metals, and limitations of the models in current use. Proposals are made for further work. (author)

Bulk Genotyping of Biopsies Can Create Spurious Evidence for Hetereogeneity in Mutation Content.

Directory of Open Access Journals (Sweden)

Rumen Kostadinov

2016-04-01

Full Text Available When multiple samples are taken from the neoplastic tissues of a single patient, it is natural to compare their mutation content. This is often done by bulk genotyping of whole biopsies, but the chance that a mutation will be detected in bulk genotyping depends on its local frequency in the sample. When the underlying mutation count per cell is equal, homogenous biopsies will have more high-frequency mutations, and thus more detectable mutations, than heterogeneous ones. Using simulations, we show that bulk genotyping of data simulated under a neutral model of somatic evolution generates strong spurious evidence for non-neutrality, because the pattern of tissue growth systematically generates differences in biopsy heterogeneity. Any experiment which compares mutation content across bulk-genotyped biopsies may therefore suggest mutation rate or selection intensity variation even when these forces are absent. We discuss computational and experimental approaches for resolving this problem.

Bulk Genotyping of Biopsies Can Create Spurious Evidence for Hetereogeneity in Mutation Content.

Science.gov (United States)

Kostadinov, Rumen; Maley, Carlo C; Kuhner, Mary K

2016-04-01

When multiple samples are taken from the neoplastic tissues of a single patient, it is natural to compare their mutation content. This is often done by bulk genotyping of whole biopsies, but the chance that a mutation will be detected in bulk genotyping depends on its local frequency in the sample. When the underlying mutation count per cell is equal, homogenous biopsies will have more high-frequency mutations, and thus more detectable mutations, than heterogeneous ones. Using simulations, we show that bulk genotyping of data simulated under a neutral model of somatic evolution generates strong spurious evidence for non-neutrality, because the pattern of tissue growth systematically generates differences in biopsy heterogeneity. Any experiment which compares mutation content across bulk-genotyped biopsies may therefore suggest mutation rate or selection intensity variation even when these forces are absent. We discuss computational and experimental approaches for resolving this problem.

Dose-rate effects on the bulk etch-rate of CR-39 track detector exposed to low-LET radiations

CERN Document Server

Yamauchi, T; Oda, K; Ikeda, T; Honda, Y; Tagawa, S

1999-01-01

The effect of gamma-rays and pulsed electrons has been investigated on the bulk etch rate of CR-39 detector at doses up to 100 kGy under various dose-rate between 0.0044 and 35.0 Gy/s. The bulk etch rate increased exponentially with the dose at every examined dose-rates. It was reveled to be strongly depend on the dose-rate: the bulk etch rate was decreased with increasing dose-rate at the same total dose. A primitive model was proposed to explain the dose-rate effect in which oxygen dissolved was assumed to dominate the damage formation process.

Auditory bones obtained by synchrotron radiation computed tomography at SPring-8

International Nuclear Information System (INIS)

Hashimoto, E.; Sugiyama, H.; Maksimenko, A.

2005-01-01

A series tomograms and 3D reconstructions of the inner structure of the human auditory bone were obtained for the first time by employing absorption X-ray computed tomography using a synchrotron radiation. The experiment was performed at the very long transport channel beam line BL29XUL, where X-ray were available at 1000m from the source point. This method is great worth to making anatomically auditory structure observations without bursting the specimens. (author)

Development of Parallel Computing Framework to Enhance Radiation Transport Code Capabilities for Rare Isotope Beam Facility Design

Energy Technology Data Exchange (ETDEWEB)

Kostin, Mikhail [Michigan State Univ., East Lansing, MI (United States); Mokhov, Nikolai [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Niita, Koji [Research Organization for Information Science and Technology, Ibaraki-ken (Japan)

2013-09-25

A parallel computing framework has been developed to use with general-purpose radiation transport codes. The framework was implemented as a C++ module that uses MPI for message passing. It is intended to be used with older radiation transport codes implemented in Fortran77, Fortran 90 or C. The module is significantly independent of radiation transport codes it can be used with, and is connected to the codes by means of a number of interface functions. The framework was developed and tested in conjunction with the MARS15 code. It is possible to use it with other codes such as PHITS, FLUKA and MCNP after certain adjustments. Besides the parallel computing functionality, the framework offers a checkpoint facility that allows restarting calculations with a saved checkpoint file. The checkpoint facility can be used in single process calculations as well as in the parallel regime. The framework corrects some of the known problems with the scheduling and load balancing found in the original implementations of the parallel computing functionality in MARS15 and PHITS. The framework can be used efficiently on homogeneous systems and networks of workstations, where the interference from the other users is possible.

Li-Doped Ionic Liquid Electrolytes: From Bulk Phase to Interfacial Behavior

Science.gov (United States)

Haskins, Justin B.; Lawson, John W.

2016-01-01

Ionic liquids have been proposed as candidate electrolytes for high-energy density, rechargeable batteries. We present an extensive computational analysis supported by experimental comparisons of the bulk and interfacial properties of a representative set of these electrolytes as a function of Li-salt doping. We begin by investigating the bulk electrolyte using quantum chemistry and ab initio molecular dynamics to elucidate the solvation structure of Li(+). MD simulations using the polarizable force field of Borodin and coworkers were then performed, from which we obtain an array of thermodynamic and transport properties. Excellent agreement is found with experiments for diffusion, ionic conductivity, and viscosity. Combining MD simulations with electronic structure computations, we computed the electrochemical window of the electrolytes across a range of Li(+)-doping levels and comment on the role of the liquid environment. Finally, we performed a suite of simulations of these Li-doped electrolytes at ideal electrified interfaces to evaluate the differential capacitance and the equilibrium Li(+) distribution in the double layer. The magnitude of differential capacitance is in good agreement with our experiments and exhibits the characteristic camel-shaped profile. In addition, the simulations reveal Li(+) to be highly localized to the second molecular layer of the double layer, which is supported by additional computations that find this layer to be a free energy minimum with respect to Li(+) translation.

Computation of the glandular radiation dose in digital tomosynthesis of the breast

International Nuclear Information System (INIS)

Sechopoulos, Ioannis; Suryanarayanan, Sankararaman; Vedantham, Srinivasan; D'Orsi, Carl; Karellas, Andrew

2007-01-01

Tomosynthesis of the breast is currently a topic of intense interest as a logical next step in the evolution of digital mammography. This study reports on the computation of glandular radiation dose in digital tomosynthesis of the breast. Previously, glandular dose estimations in tomosynthesis have been performed using data from studies of radiation dose in conventional planar mammography. This study evaluates, using Monte Carlo methods, the normalized glandular dose (D g N) to the breast during a tomosynthesis study, and characterizes its dependence on breast size, tissue composition, and x-ray spectrum. The conditions during digital tomosynthesis imaging of the breast were simulated using a computer program based on the Geant4 toolkit. With the use of simulated breasts of varying size, thickness and tissue composition, the D g N to the breast tissue was computed for varying x-ray spectra and tomosynthesis projection angle. Tomosynthesis projections centered about both the cranio-caudal (CC) and medio-lateral oblique (MLO) views were simulated. For each projection angle, the ratio of the glandular dose for that projection to the glandular dose for the zero degree projection was computed. This ratio was denoted the relative glandular dose (RGD) coefficient, and its variation under different imaging parameters was analyzed. Within mammographic energies, the RGD was found to have a weak dependence on glandular fraction and x-ray spectrum for both views. A substantial dependence on breast size and thickness was found for the MLO view, and to a lesser extent for the CC view. Although RGD values deviate substantially from unity as a function of projection angle, the RGD averaged over all projections in a complete tomosynthesis study varies from 0.91 to 1.01. The RGD results were fit to mathematical functions and the resulting equations are provided

WE-B-BRD-01: Innovation in Radiation Therapy Planning II: Cloud Computing in RT

International Nuclear Information System (INIS)

Moore, K; Kagadis, G; Xing, L; McNutt, T

2014-01-01

As defined by the National Institute of Standards and Technology, cloud computing is “a model for enabling ubiquitous, convenient, on-demand network access to a shared pool of configurable computing resources (e.g., networks, servers, storage, applications, and services) that can be rapidly provisioned and released with minimal management effort or service provider interaction.” Despite the omnipresent role of computers in radiotherapy, cloud computing has yet to achieve widespread adoption in clinical or research applications, though the transition to such “on-demand” access is underway. As this transition proceeds, new opportunities for aggregate studies and efficient use of computational resources are set against new challenges in patient privacy protection, data integrity, and management of clinical informatics systems. In this Session, current and future applications of cloud computing and distributed computational resources will be discussed in the context of medical imaging, radiotherapy research, and clinical radiation oncology applications. Learning Objectives: Understand basic concepts of cloud computing. Understand how cloud computing could be used for medical imaging applications. Understand how cloud computing could be employed for radiotherapy research.4. Understand how clinical radiotherapy software applications would function in the cloud

WE-B-BRD-01: Innovation in Radiation Therapy Planning II: Cloud Computing in RT

Energy Technology Data Exchange (ETDEWEB)

Moore, K [University of California, San Diego, La Jolla, CA (United States); Kagadis, G [University Patras, Rion - Patras (Greece); Xing, L [Stanford University, Stanford, CA (United States); McNutt, T [Johns Hopkins University, Severna Park, MD (United States)

2014-06-15

As defined by the National Institute of Standards and Technology, cloud computing is “a model for enabling ubiquitous, convenient, on-demand network access to a shared pool of configurable computing resources (e.g., networks, servers, storage, applications, and services) that can be rapidly provisioned and released with minimal management effort or service provider interaction.” Despite the omnipresent role of computers in radiotherapy, cloud computing has yet to achieve widespread adoption in clinical or research applications, though the transition to such “on-demand” access is underway. As this transition proceeds, new opportunities for aggregate studies and efficient use of computational resources are set against new challenges in patient privacy protection, data integrity, and management of clinical informatics systems. In this Session, current and future applications of cloud computing and distributed computational resources will be discussed in the context of medical imaging, radiotherapy research, and clinical radiation oncology applications. Learning Objectives: Understand basic concepts of cloud computing. Understand how cloud computing could be used for medical imaging applications. Understand how cloud computing could be employed for radiotherapy research.4. Understand how clinical radiotherapy software applications would function in the cloud.

Rad World -- computer-animated video radiation and hazardous waste-management science curriculum

International Nuclear Information System (INIS)

Powell, B.

1996-01-01

The Rad World computer-animated video and curriculum materials were developed through a grant from the Waste-management Education and Research Consortium. The package, which includes a computer-animated video, hands-on activities, and multidisciplinary lessons concerning radiation and hazardous-waste management, was created to approach these subjects in an informative, yet entertaining, manner. The lessons and video, designed to supplement studies of energy and physical science at the middle school and high school level, also implement quality and consistent science education as outlined by the New Mexico Science Standards and Benchmarks (1995). Consistent with the curriculum standards and benchmarks, the curriculum includes library research, collaborative learning, hands-on-science, and discovery learning. Pre- and post-tests are included

Computer aided dosimetry and verification of exposure to radiation. Technical report

International Nuclear Information System (INIS)

Waller, D.; Stodilka, R.Z.; Leach, K.E.; Prud'homme-Lalonde, L.

2002-06-01

In the timeframe following the September 11th attacks on the United States, increased emphasis has been placed on Chemical, Biological, Radiological and Nuclear (CBRN) preparedness. Of prime importance is rapid field assessment of potential radiation exposure to Canadian Forces field personnel. This work set up a framework for generating an 'expert' computer system for aiding and assisting field personnel in determining the extent of radiation insult to military personnel. Data was gathered by review of the available literature, discussions with medical and health physics personnel having hands-on experience dealing with radiation accident victims, and from experience of the principal investigator. Flow charts and generic data fusion algorithms were developed. Relationships between known exposure parameters, patient interview and history, clinical symptoms, clinical work-ups, physical dosimetry, biological dosimetry, and dose reconstruction as critical data indicators were investigated. The data obtained was examined in terms of information theory. A main goal was to determine how best to generate an adaptive model (i.e. when more data becomes available, how is the prediction improved). Consideration was given to determination of predictive algorithms for health outcome. In addition, the concept of coding an expert medical treatment advisor system was developed. (author)

THE ASSESSMENT MODELS OF AIR POLLUTION DURING TRANSPORTATION OF BULK CARGO

Directory of Open Access Journals (Sweden)

M. M. Biliaiev

2016-10-01

Full Text Available Purpose. The scientific work is concentrated on development of 3D, 2D numerical models for the prediction of atmospheric pollution during transport of bulk cargo in the railway car. Methodology. To solve this problem numerical models were developed, based on the use of the motion equations of inviscid incompressible fluid and mass transfer, to determine the field of wind velocity near the cars and dispersion of dust in the atmosphere. For the numerical integration of the pollutant transport equation implicit alternating-triangular difference scheme was used. When constructing a difference scheme splitting of the transport equation is carried out that allows us to construct an efficient algorithm for solving a differential problem. Unknown value of the pollutant concentration at every step of splitting is determined by the explicit scheme – the method of point-to-point computation, which provides a simple numerical implementation of splitting equations. For numerical integration of the 3D equation for the velocity potential method of Richardson is applied. For numerical integration of the 2D equation for the velocity potential the method of total approximation is applied. The developed numerical models are the basis of established software package. On the basis of the constructed numerical models a computational experiment to assess the level of air pollution when demolition of coal dust from the gondola car was carried out. Findings. 3D, 2D numerical models that belong to the class «diagnostic models» were developed. These models take into account the main physical factors affecting the process of dust pollution dispersion in the atmosphere during transportation of bulk cargo, but require small costs of the computer time in the practice at the low and medium power machines. These models are used for serial calculations of various situations of scenarios related to issues of environmental protection and pollution intensity diagnostics for

Ion specific correlations in bulk and at biointerfaces

International Nuclear Information System (INIS)

Kalcher, I; Horinek, D; Netz, R R; Dzubiella, J

2009-01-01

Ion specific effects are ubiquitous in any complex colloidal or biological fluid in bulk or at interfaces. The molecular origins of these 'Hofmeister effects' are not well understood and their theoretical description poses a formidable challenge to the modeling and simulation community. On the basis of the combination of atomistically resolved molecular dynamics (MD) computer simulations and statistical mechanics approaches, we present a few selected examples of specific electrolyte effects in bulk, at simple neutral and charged interfaces, and on a short α-helical peptide. The structural complexity in these strongly Coulomb-correlated systems is highlighted and analyzed in the light of available experimental data. While in general the comparison of MD simulations to experiments often lacks quantitative agreement, mostly because molecular force fields and coarse-graining procedures remain to be optimized, the consensus as regards trends provides important insights into microscopic hydration and binding mechanisms.

Ion specific correlations in bulk and at biointerfaces.

Science.gov (United States)

Kalcher, I; Horinek, D; Netz, R R; Dzubiella, J

2009-10-21

Ion specific effects are ubiquitous in any complex colloidal or biological fluid in bulk or at interfaces. The molecular origins of these 'Hofmeister effects' are not well understood and their theoretical description poses a formidable challenge to the modeling and simulation community. On the basis of the combination of atomistically resolved molecular dynamics (MD) computer simulations and statistical mechanics approaches, we present a few selected examples of specific electrolyte effects in bulk, at simple neutral and charged interfaces, and on a short α-helical peptide. The structural complexity in these strongly Coulomb-correlated systems is highlighted and analyzed in the light of available experimental data. While in general the comparison of MD simulations to experiments often lacks quantitative agreement, mostly because molecular force fields and coarse-graining procedures remain to be optimized, the consensus as regards trends provides important insights into microscopic hydration and binding mechanisms.

Comparison of platelet activation through hinge vs bulk flow in mechanical heart valves

Science.gov (United States)

Hedayat, Mohammadali; Borazjani, Iman

2017-11-01

Bileaflet mechanical heart valves increase the risk of thrombus formation in patients which is believed to be initiated by platelet activation. Platelets can be activated by the elevated shear stresses in the bulk flow during the systole phase or the flow through the hinge during the diastole. However, the importance of platelet activation by the bulk flow vs the hinge in MHVs has yet to be studied. Here, we investigate the contribution of each of the above mechanisms to the activation of platelets in MHs by performing simulation of the flow through a 25mm St. Jude Medical valve placed in a straight aorta. Two different gap sizes (250 and 150 micrometer) are used in this study. The simulations are done using a sharp interface curvilinear immersed boundary method along with a strong-coupling algorithm for FSI solver on overset grids. The platelet activation through the hinge for different gap sizes is compared to the activation in the bulk flow using two platelet activation models to ensure the consistency of the results. Our results for all gap sizes using different activation models show that the integration of platelet activation caused by the bulk flow is several times higher in comparison to the activation through the hinge. This work is supported by the American Heart Association Grant 13SDG17220022, and the computational resources were partly provided by Center for Computational Research (CCR) at University at Buffalo.

Measurements and TCAD Simulations of Bulk and Surface Radiation Damage Effects

CERN Document Server

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.

Characteristic of Polymer-Impregnated Cement Mortar: Composites: Bulk Density and Microstructure

International Nuclear Information System (INIS)

Younes, M.M.; Abo-El-Enein, S.A.; El-Saft, M.M.; Sadek, M.A.; Zohdy, K.M.

2010-01-01

The effect of radiation initiated polymerization of some monomers on the physical properties of polymer-incorporated mortar was studied. The monomers used were: castor oil (C.O.), 4, 4'-diphenylmethane diisocyanate (MDI) and methyl methacrylate (MMA). Polymerization was carried out by subjecting the monomer-impregnated mortar specimens to different doses of gamma radiation. Where polyurethane (pu) and polyurethane -methyl methacrylate copolymers were formed within the pore system. The influence of polymer impregnation on the various physico-mechanical characteristics of the resulting composites was studied with respect to bulk density and polymer loading. Scanning electron microscopy (SEM) was employed to study the micro-structural characteristics of the neat hardened Ordinary Portland Cement (OPC) mortar pastes and their polymer-impregnated composites

Computer Modeling of Radiation Portal Monitors for Homeland Security Applications

International Nuclear Information System (INIS)

Pagh, Richard T.; Kouzes, Richard T.; McConn, Ronald J.; Robinson, Sean M.; Schweppe, John E.; Siciliano, Edward R.

2005-01-01

Radiation Portal Monitors (RPMs) are currently being used at our nation's borders to detect potential nuclear threats. At the Pacific Northwest National Laboratory (PNNL), realistic computer models of RPMs are being developed to simulate the screening of vehicles and cargo. Detailed models of the detection equipment, vehicles, cargo containers, cargos, and radioactive sources are being used to determine the optimal configuration of detectors. These models can also be used to support work to optimize alarming algorithms so that they maximize sensitivity for items of interest while minimizing nuisance alarms triggered by legitimate radioactive material in the commerce stream. Proposed next-generation equipment is also being modeled to quantify performance and capability improvements to detect potential nuclear threats. A discussion of the methodology used to perform computer modeling for RPMs will be provided. In addition, the efforts to validate models used to perform these scenario analyses will be described. Finally, areas where improved modeling capability is needed will be discussed as a guide to future development efforts

A new computational method for simulation of charge transport in semiconductor radiation detectors

International Nuclear Information System (INIS)

Holban, I.

1993-01-01

An effective computational method for simulation of charge transport in semiconductor radiation detectors is the purpose of the present work. Basic equations for analysis include (1) Poisson's equations, (2) continuity equation for electrons and holes, (3) rate equations for deep levels, (4) current equation for electrons and holes and (5) boundary conditions. The system of equations is discretized and equidistant space and time grids is brought. The nonlinearity of the problem is overcome by using Newton-Raphson iteration scheme. Instead of solving a nonlinear boundary problem we resolve a linear matrix equation. Our computation procedure becomes very efficient using a sparse matrix. The computed program allows to calculate the charge collection efficiency and transient response for arbitrary electric fields when trapping and detrapping effects are present. The earlier literature results are reproduced. (Author)

Nuclear techniques for bulk ore analysis and their application to quality control

International Nuclear Information System (INIS)

Holmes, R.J.

1981-01-01

Bulk analysis techniques developed for the mining industry in which analyses are obtained directly from 3-30kg ore samples or from ore on conveyor belts are outlined. They include the determination of iron in iron ores from backscattered gamma radiation, shale in sedimentary iron ores from natural gamma activity, iron from a thermal-neutron capture reaction, and aluminium from the thermal neutron activation reaction

Quality Assurance Challenges for Motion-Adaptive Radiation Therapy: Gating, Breath Holding, and Four-Dimensional Computed Tomography

International Nuclear Information System (INIS)

Jiang, Steve B.; Wolfgang, John; Mageras, Gig S.

2008-01-01

Compared with conventional three-dimensional (3D) conformal radiation therapy and intensity-modulated radiation therapy treatments, quality assurance (QA) for motion-adaptive radiation therapy involves various challenges because of the added temporal dimension. Here we discuss those challenges for three specific techniques related to motion-adaptive therapy: namely respiratory gating, breath holding, and four-dimensional computed tomography. Similar to the introduction of any other new technologies in clinical practice, typical QA measures should be taken for these techniques also, including initial testing of equipment and clinical procedures, as well as frequent QA examinations during the early stage of implementation. Here, rather than covering every QA aspect in depth, we focus on some major QA challenges. The biggest QA challenge for gating and breath holding is how to ensure treatment accuracy when internal target position is predicted using external surrogates. Recommended QA measures for each component of treatment, including simulation, planning, patient positioning, and treatment delivery and verification, are discussed. For four-dimensional computed tomography, some major QA challenges have also been discussed

Comparing Classical Water Models Using Molecular Dynamics to Find Bulk Properties

Science.gov (United States)

Kinnaman, Laura J.; Roller, Rachel M.; Miller, Carrie S.

2018-01-01

A computational chemistry exercise for the undergraduate physical chemistry laboratory is described. In this exercise, students use the molecular dynamics package Amber to generate trajectories of bulk liquid water for 4 different water models (TIP3P, OPC, SPC/E, and TIP4Pew). Students then process the trajectory to calculate structural (radial…

The use of symbolic computation in radiative, energy, and neutron transport calculations. Final report

International Nuclear Information System (INIS)

Frankel, J.I.

1997-01-01

This investigation used sysmbolic manipulation in developing analytical methods and general computational strategies for solving both linear and nonlinear, regular and singular integral and integro-differential equations which appear in radiative and mixed-mode energy transport. Contained in this report are seven papers which present the technical results as individual modules

Computational methodology for the Oak Ridge Research Reactor (ORR) and Bulk Shielding Reactor (BSR): cross-section and validation. Volume 1

International Nuclear Information System (INIS)

Miller, L.F.; Williams, M.L.

1986-03-01

A neutronics library suitable for low-enrichment uranium (LEU) and high-enrichment uranium (HEU) fueled cores for both the Oak Ridge Research Reactor (ORR) and the Bulk Shielding Reactor (BSR) is documented herein. The library is obtained from version V of the Evaluated Nuclear Data File (ENDF/B-V) and contains 223 nuclides weighted over a variety of region-dependent neutron spectra. Self-shielding and zone-weighting effects are incorporated with 227-group calculations for several reactor-core configurations. Libraries are archived for both transport and diffusion theory seven-group calculations. Complete listings of processing details are included so that libraries with different specifications can be easily obtained. Results from validation calculations indicate that the neutronics libraries obtained from this effort are suitable for neutronics computations for the ORR and BSR. 12 refs., 5 figs., 15 tabs

Shielding from cosmic radiation for interplanetary missions Active and passive methods

CERN Document Server

Spillantini, P; Durante, M; Müller-Mellin, R; Reitz, G; Rossi, L; Shurshakov, V; Sorbi, M

2007-01-01

Shielding is arguably the main countermeasure for the exposure to cosmic radiation during interplanetary exploratory missions. However, shielding of cosmic rays, both of galactic or solar origin, is problematic, because of the high energy of the charged particles involved and the nuclear fragmentation occurring in shielding materials. Although computer codes can predict the shield performance in space, there is a lack of biological and physical measurements to benchmark the codes. An attractive alternative to passive, bulk material shielding is the use of electromagnetic fields to deflect the charged particles from the spacecraft target. Active shielding concepts based on electrostatic fields, plasma, or magnetic fields have been proposed in the past years, and should be revised based on recent technological improvements. To address these issues, the European Space Agency (ESA) established a Topical Team (TT) in 2002 including European experts in the field of space radiation shielding and superconducting magn...

Excess lifetime cancer mortality risk attributable to radiation exposure from computed tomography examinations in children

NARCIS (Netherlands)

Chodick, Gabriel; Ronckers, Cécile M.; Shalev, Varda; Ron, Elaine

2007-01-01

The use of computed tomography in Israel has been growing rapidly during recent decades. The major drawback of this important technology is the exposure to ionizing radiation, especially among children who have increased organ radiosensitivity and a long lifetime to potentially develop

Computer modeling characterization, and applications of Gallium Arsenide Gunn diodes in radiation environments

Energy Technology Data Exchange (ETDEWEB)

El- Basit, Wafaa Abd; El-Ghanam, Safaa Mohamed; Kamh, Sanaa Abd El-Tawab [Electronics Research Laboratory, Physics Department, Faculty of Women for Arts, Science and Education, Ain-Shams University, Cairo (Egypt); Abdel-Maksood, Ashraf Mosleh; Soliman, Fouad Abd El-Moniem Saad [Nuclear Materials Authority, Cairo (Egypt)

2016-10-15

The present paper reports on a trial to shed further light on the characterization, applications, and operation of radar speed guns or Gunn diodes on different radiation environments of neutron or γ fields. To this end, theoretical and experimental investigations of microwave oscillating system for outer-space applications were carried out. Radiation effects on the transient parameters and electrical properties of the proposed devices have been studied in detail with the application of computer programming. Also, the oscillation parameters, power characteristics, and bias current were plotted under the influence of different γ and neutron irradiation levels. Finally, shelf or oven annealing processes were shown to be satisfactory techniques to recover the initial characteristics of the irradiated devices.

Ab-initio Computation of the Electronic, transport, and Bulk Properties of Calcium Oxide.

Science.gov (United States)

Mbolle, Augustine; Banjara, Dipendra; Malozovsky, Yuriy; Franklin, Lashounda; Bagayoko, Diola

We report results from ab-initio, self-consistent, local Density approximation (LDA) calculations of electronic and related properties of calcium oxide (CaO) in the rock salt structure. We employed the Ceperley and Alder LDA potential and the linear combination of atomic orbitals (LCAO) formalism. Our calculations are non-relativistic. We implemented the LCAO formalism following the Bagayoko, Zhao, and Williams (BZW) method, as enhanced by Ekuma and Franklin (BZW-EF). The BZW-EF method involves a methodical search for the optimal basis set that yields the absolute minima of the occupied energies, as required by density functional theory (DFT). Our calculated, indirect band gap of 6.91eV, from towards the L point, is in excellent agreement with experimental value of 6.93-7.7eV, at room temperature (RT). We have also calculated the total (DOS) and partial (pDOS) densities of states as well as the bulk modulus. Our calculated bulk modulus is in excellent agreement with experiment. Work funded in part by the US Department of Energy (DOE), National Nuclear Security Administration (NNSA) (Award No.DE-NA0002630), the National Science Foundation (NSF) (Award No, 1503226), LaSPACE, and LONI-SUBR.

Computer-assisted planning and dosimetry for radiation treatment of head and neck cancer in Cameroon

International Nuclear Information System (INIS)

Yomi, J.; Ngniah, A.; Kingue, S.; Muna, W.F.T.; Durosinmi-Etti, F.A.

1995-01-01

This evaluation was part of a multicenter, multinational study sponsored by the International Agency for Atomic Energy (Vienna) to investigate a simple, reliable computer-assisted planning and dosimetry system for radiation treatment of head and neck cancers in developing countries. Over a 13-month period (April 1992-April 1993), 120 patients with histologically-proven head or neck cancer were included in the evaluation. In each patient, planning and dosimetry were done both manually and using the computer-assisted system. The manual and computerized systems were compared on the basis of accuracy of determination of the outer contour, target volume, and critical organs; volume inequality resolution; structure heterogeneity correction; selection of the number, angle, and size of beams; treatment time calculation; availability of dosimetry predictions; and duration and cost of the procedure. Results demonstrated that the computer-assisted procedure was superior over the manual procedure, despite less than optimal software. The accuracy provided by the completely computerized procedure is indispensable for Level II radiation therapy, which is particularly useful in tumors of the sensitive, complex structures in the head and neck. (authors). 7 refs., 3 tabs

Investigation and computer modeling of radiation and thermal decomposition of polystyrene scintillators

Science.gov (United States)

Sakhno, Tamara V.; Pustovit, Sergey V.; Borisenko, Artem Y.; Senchishin, Vitaliy G.; Barashkov, Nikolay N.

2003-12-01

This paper is devoted to the investigation and computer modeling of radiation and thermal decomposition of luminescent polystyrene compositions. It has been shown, that the stability of the optical properties of luminescent polymer composition depends on its material structure. On the basis of quantum-chemical calculation has been obtained the possible products of PS gamma-radiolysis and the effect of formation of fragments with conjugated double bonds and products with quinone structure has been investigated.

Development and validation of Monte Carlo dose computations for contrast-enhanced stereotactic synchrotron radiation therapy

International Nuclear Information System (INIS)

Vautrin, M.

2011-01-01

Contrast-enhanced stereotactic synchrotron radiation therapy (SSRT) is an innovative technique based on localized dose-enhancement effects obtained by reinforced photoelectric absorption in the tumor. Medium energy monochromatic X-rays (50 - 100 keV) are used for irradiating tumors previously loaded with a high-Z element. Clinical trials of SSRT are being prepared at the European Synchrotron Radiation Facility (ESRF), an iodinated contrast agent will be used. In order to compute the energy deposited in the patient (dose), a dedicated treatment planning system (TPS) has been developed for the clinical trials, based on the ISOgray TPS. This work focuses on the SSRT specific modifications of the TPS, especially to the PENELOPE-based Monte Carlo dose engine. The TPS uses a dedicated Monte Carlo simulation of medium energy polarized photons to compute the deposited energy in the patient. Simulations are performed considering the synchrotron source, the modeled beamline geometry and finally the patient. Specific materials were also implemented in the voxelized geometry of the patient, to consider iodine concentrations in the tumor. The computation process has been optimized and parallelized. Finally a specific computation of absolute doses and associated irradiation times (instead of monitor units) was implemented. The dedicated TPS was validated with depth dose curves, dose profiles and absolute dose measurements performed at the ESRF in a water tank and solid water phantoms with or without bone slabs. (author) [fr

Radiation defects in Te-implanted germanium. Electron microscopy and computer simulation studies

International Nuclear Information System (INIS)

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)

Photothermal Infrared Radiometry in Experimental Studies of the Pyroelectric Properties of Bulk Materials

Science.gov (United States)

Aleksandrov, S. E.; Gavrilov, G. A.; Kapralov, A. A.; Muratikov, K. L.; Sotnikova, G. Yu.

2017-12-01

A simple and efficient method for determining the pyrolelectric coefficients of ferroelectric and pyroelectric bulk materials by taking into account the heat exchange of a sample with the environment is proposed on the basis of the radiometric registration of the variation dynamics of the temperature of the surface when it is exposed to laser radiation in the form of a temporal step.

Computation of coupled surface radiation and natural convection in an inclined form cavity

International Nuclear Information System (INIS)

Amraqui, Samir; Mezrhab, Ahmed; Abid, Cherifa

2011-01-01

The present paper is concerned with computation of the radiation-natural convection interactions in an inclined form cavity. The cavity contains two symmetrically identical isothermal blocks and is vented by two opening located in a vertical median axis at the top and the bottom parts of the cavity. Calculations are made by using a finite volume method and an efficient numerical procedure is introduced for calculating the view factors, with shadow effects included. Effects of Rayleigh number Ra and inclination angle φ are investigated for Pr = 0.71 in presence and in absence of the radiation exchange. Results are reported in terms of isotherms, streamlines, local and average Nusselt numbers and mass flow rate. In light of the obtained results, we can conclude that the heat transfer decreases with increasing φ. In addition, the increase of Ra and the taking into account of the radiation exchange produce a considerable increase in the heat transfer.

Lithium niobate bulk crystallization promoted by CO{sub 2} laser radiation

Energy Technology Data Exchange (ETDEWEB)

Ferreira, N.M., E-mail: nmferreira@ua.pt [i3N - Aveiro, Physics Department, Aveiro University, Campus Universitario de Santiago, 3810-193 Aveiro (Portugal); Costa, F.M. [i3N - Aveiro, Physics Department, Aveiro University, Campus Universitario de Santiago, 3810-193 Aveiro (Portugal); Nogueira, R.N. [Instituto de Telecomunicacoes, 3810-193 Aveiro (Portugal); Graca, M.P.F. [i3N - Aveiro, Physics Department, Aveiro University, Campus Universitario de Santiago, 3810-193 Aveiro (Portugal)

2012-09-15

Highlights: Black-Right-Pointing-Pointer Crystallization of LiNbO{sub 3} nanocrystals in a SiO{sub 2} matrix by CO{sub 2} laser irradiation process. Black-Right-Pointing-Pointer Samples heat-treated at 650 Degree-Sign C (4 h) and laser treated (4 W/500 s) show similar morphology. Black-Right-Pointing-Pointer Glass-ceramics produced by laser process requires a very low processing time. - Abstract: The crystallization induced by laser radiation is a very promising technique to promote glass/ceramic transformation, being already used to produce crystalline patterns on glass surfaces. In this work, a SiO{sub 2}-Li{sub 2}O-Nb{sub 2}O{sub 5} glass, prepared by the sol-gel route, was submitted to CO{sub 2} laser radiation and conventional heat-treatments in order to induce the LiNbO{sub 3} crystallization. The structure and morphology of the samples prepared by both routes was analyzed as a function of exposure time, radiation power and heat-treatment temperatures by XRD, Raman spectroscopy and SEM. The results reveal a correlation between the crystallization degree of LiNbO{sub 3} particles and glass matrix with the heat treatment type and experimental parameters. An heat-treatment at 650 Degree-Sign C/4 h was necessary to induce crystallization in heat treatments samples while 4 W/500 s was enough for laser radiation ones, corresponding a reduction time processing of {approx}14 000 s.

3D histomorphometric quantification of trabecular bones by computed microtomography using synchrotron radiation.

Science.gov (United States)

Nogueira, L P; Braz, D; Barroso, R C; Oliveira, L F; Pinheiro, C J G; Dreossi, D; Tromba, G

2010-12-01

Conventional bone histomorphometry is an important method for quantitative evaluation of bone microstructure. X-ray computed microtomography is a non-invasive technique, which can be used to evaluate histomorphometric indices in trabecular bones (BV/TV, BS/BV, Tb.N, Tb.Th, Tb.Sp). In this technique, 3D images are used to quantify the whole sample, differently from the conventional one, in which the quantification is performed in 2D slices and extrapolated for 3D case. In this work, histomorphometric quantification using synchrotron 3D X-ray computed microtomography was performed to quantify the bone structure at different skeletal sites as well as to investigate the effects of bone diseases on quantitative understanding of bone architecture. The images were obtained at Synchrotron Radiation for MEdical Physics (SYRMEP) beamline, at ELETTRA synchrotron radiation facility, Italy. Concerning the obtained results for normal and pathological bones from same skeletal sites and individuals, from our results, a certain declining bone volume fraction was achieved. The results obtained could be used in forming the basis for comparison of the bone microarchitecture and can be a valuable tool for predicting bone fragility. Copyright © 2010 Elsevier Ltd. All rights reserved.

Effect of sample thickness on the extracted near-infrared bulk optical properties of Bacillus subtilis in liquid culture.

Science.gov (United States)

Dzhongova, Elitsa; Harwood, Colin R; Thennadil, Suresh N

2011-11-01

In order to determine the bulk optical properties of a Bacillus subtilis culture during growth phase we investigated the effect of sample thickness on measurements taken with different measurement configurations, namely total diffuse reflectance and total diffuse transmittance. The bulk optical properties were extracted by inverting the measurements using the radiative transfer theory. While the relationship between reflectance and biomass changes with sample thickness and the intensity (absorbance) levels vary significantly for both reflectance and transmittance measurements, the extracted optical properties show consistent behavior in terms of both the relationship with biomass and magnitude. This observation indicates the potential of bulk optical properties for building models that could be more easily transferable compared to those built using raw measurements.

Nationwide radiation dose survey of computed tomography for fetal skeletal dysplasias

Energy Technology Data Exchange (ETDEWEB)

Miyazaki, Osamu [National Center for Child Health and Development, Department of Radiology, Setagaya-ku, Tokyo (Japan); Sawai, Hideaki [Hyogo College of Medicine, Department of Obstetrics and Gynecology, Nishinomiya-shi, Hyogo (Japan); Murotsuki, Jun [Miyagi Children' s Hospital, Department of Maternal and Fetal Medicine, Sendai-shi, Miyagi (Japan); Tohoku University Graduate School of Medicine, Department of Advanced Fetal and Developmental Medicine, Sendai-shi, Miyagi (Japan); Nishimura, Gen [Tokyo Metropolitan Children' s Medical Center, Department of Pediatric Imaging, Fuchu-shi, Tokyo (Japan); Horiuchi, Tetsuya [National Center for Child Health and Development, Department of Radiology, Setagaya-ku, Tokyo (Japan); Osaka University, Department of Medical Physics and Engineering, Division of Medical Technology and Science, Course of Health Science, Graduate School of Medicine, Suita, Osaka (Japan)

2014-08-15

Recently, computed tomography (CT) has been used to diagnose fetal skeletal dysplasia. However, no surveys have been conducted to determine the radiation exposure dose and the diagnostic reference level (DRL). To collect CT dose index volume (CTDIvol) and dose length product (DLP) data from domestic hospitals implementing fetal skeletal 3-D CT and to establish DRLs for Japan. Scan data of 125 cases of 20 protocols from 16 hospitals were analyzed. The minimum, first-quartile, median, third-quartile and maximum values of CTDIvol and DLP were determined. The time-dependent change in radiation dose setting in hospitals with three or more cases with scans was also examined. The minimum, first-quartile, median, third-quartile and maximum CTDIvol values were 2.1, 3.7, 7.7, 11.3 and 23.1 mGy, respectively, and these values for DLP were 69.0, 122.3, 276.8, 382.6 and 1025.6 mGy.cm, respectively. Six of the 12 institutions reduced the dose setting during the implementation period. The DRLs of CTDIvol and DLP for fetal CT were 11.3 mGy and 382.6 mGy.cm, respectively. Institutions implementing fetal CT should use these established DRLs as the standard and make an effort to reduce radiation exposure by voluntarily decreasing the dose. (orig.)

Computer aided dosimetry and verification of exposure to radiation. Technical report

Energy Technology Data Exchange (ETDEWEB)

Waller, D. [SAIC Canada (Canada); Stodilka, R.Z.; Leach, K.E.; Prud' homme-Lalonde, L. [Defence R and D Canada (DRDC), Radiation Effects Group, Space Systems and Technology, Ottawa, Ontario (Canada)

2002-06-15

In the timeframe following the September 11th attacks on the United States, increased emphasis has been placed on Chemical, Biological, Radiological and Nuclear (CBRN) preparedness. Of prime importance is rapid field assessment of potential radiation exposure to Canadian Forces field personnel. This work set up a framework for generating an 'expert' computer system for aiding and assisting field personnel in determining the extent of radiation insult to military personnel. Data was gathered by review of the available literature, discussions with medical and health physics personnel having hands-on experience dealing with radiation accident victims, and from experience of the principal investigator. Flow charts and generic data fusion algorithms were developed. Relationships between known exposure parameters, patient interview and history, clinical symptoms, clinical work-ups, physical dosimetry, biological dosimetry, and dose reconstruction as critical data indicators were investigated. The data obtained was examined in terms of information theory. A main goal was to determine how best to generate an adaptive model (i.e. when more data becomes available, how is the prediction improved). Consideration was given to determination of predictive algorithms for health outcome. In addition, the concept of coding an expert medical treatment advisor system was developed. (author)

Comparative analysis of different approaches to the computation of long-wave radiation balance of water air systems

International Nuclear Information System (INIS)

Zhukovskii, K.; Nourani, Y.; Monte, L.

1999-01-01

In the present paper, the net long-wave radiation balance of the water-air environmental systems is analysed on the base of several semi-empirical approaches. Various theoretical models of infrared atmospheric radiation are reviewed. Factors, affecting their behavior are considered. Special attention is paid to physical conditions under which those models are applicable. Atmospheric and net infrared radiation fluxes are computed and compared under clear and cloudy sky. Results are presented in graphical form. Conclusions are made on the applicability of models considered for evaluating infrared radiation fluxes in environmental conditions of Central Italy. On the base of present analysis Anderson's model is chosen for future calculations of heat budget of lakes in Central Italy [it

Ultrasound appearance of radiation-induced hepatic injury. Correlation with computed tomography and magnetic resonance imaging

International Nuclear Information System (INIS)

Garra, B.S.; Shawker, T.H.; Chang, R.; Kaplan, K.; White, R.D.

1988-01-01

The ultrasound findings in three cases of radiation-induced hepatic injury are described and compared with computed tomography and magnetic resonance imaging findings. Fatty infiltration of the liver was present in two of the cases in which concurrent chemotherapy was being administered. On ultrasound B-scans, the regions of radiation injury were hypoechoic relative to the remainder of the liver. This finding was more obvious in the patients with fatty livers. CT scans on the patients with fatty infiltrated livers showed higher attenuation in the irradiated region than in unexposed liver. In the patient where no fatty infiltration was present, the radiated section of liver had lower attenuation consistent with previous reports. Magnetic resonance imaging showed decreased signal in the exposed areas on T1 weighted images

Near-surface and bulk behavior of Ag in SiC

International Nuclear Information System (INIS)

Xiao, H.Y.; Zhang, Y.; Snead, L.L.; Shutthanandan, V.; Xue, H.Z.; Weber, W.J.

2012-01-01

Highlights: ► Ag release from SiC poses problems in safe operation of nuclear reactors. ► Near-surface and bulk behavior of Ag are studied by ab initio and ion beam methods. ► Ag prefers to adsorb on the surface rather than in the bulk SiC. ► At high temperature Ag desorbs from the surface instead of diffusion into bulk SiC. ► Surface diffusion may be a dominating mechanism accounting for Ag release from SiC. - Abstract: The diffusive release of fission products, such as Ag, from TRISO particles at high temperatures has raised concerns regarding safe and economic operation of advanced nuclear reactors. Understanding the mechanisms of Ag diffusion is thus of crucial importance for effective retention of fission products. Two mechanisms, i.e., grain boundary diffusion and vapor or surface diffusion through macroscopic structures such as nano-pores or nano-cracks, remain in debate. In the present work, an integrated computational and experimental study of the near-surface and bulk behavior of Ag in silicon carbide (SiC) has been carried out. The ab initio calculations show that Ag prefers to adsorb on the SiC surface rather than in the bulk, and the mobility of Ag on the surface is high. The energy barrier for Ag desorption from the surface is calculated to be 0.85–1.68 eV, and Ag migration into bulk SiC through equilibrium diffusion process is not favorable. Experimentally, Ag ions are implanted into SiC to produce Ag profiles buried in the bulk and peaked at the surface. High-temperature annealing leads to Ag release from the surface region instead of diffusion into the interior of SiC. It is suggested that surface diffusion through mechanical structural imperfection, such as vapor transport through cracks in SiC coatings, may be a dominating mechanism accounting for Ag release from the SiC in the nuclear reactor.

Collection and analysis of environmental radiation data using a desktop computer

International Nuclear Information System (INIS)

Gogolak, C.V.

1982-04-01

A portable instrumentation sytem using a Hewlett-Packard HP-9825 desktop computer for the collection and analysis of environmental radiation data is described. Procedures for the transmission of data between the HP-9825 and various nuclear counters are given together with a description of the necessary hardware and software. Complete programs for the analysis of Ge(Li) and NaI(Tl) gamma-ray spectra, high pressure ionization chamber monitor data, 86 Kr monitor data and air filter sample alpha particle activity measurements are presented. Some utility programs, intended to increase system flexibility, are included

Computer simulation for synchrotron radiation based X-ray fluorescent microtomography

International Nuclear Information System (INIS)

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)

Mathematical model of a phantom developed for use in calculations of radiation dose to the body and major internal organs of a Japanese adult

International Nuclear Information System (INIS)

Kerr, G.D.; Hwang, J.M.; Jones, R.M.

1976-05-01

A mathematical model of a phantom simulating the body and major internal organs of a Japanese adult has been developed for use in computer calculations of radiation dose. The total body height of the mathematical phantom is 162 cm, and the total body mass is 55 kg based on densities of 0.3, 1.4, and 1.0 g/cm 3 for the lung, skeleton, and bulk tissues of the body, respectively

High-intensity xenon plasma discharge lamp for bulk-sensitive high-resolution photoemission spectroscopy.

Science.gov (United States)

Souma, S; Sato, T; Takahashi, T; Baltzer, P

2007-12-01

We have developed a highly brilliant xenon (Xe) discharge lamp operated by microwave-induced electron cyclotron resonance (ECR) for ultrahigh-resolution bulk-sensitive photoemission spectroscopy (PES). We observed at least eight strong radiation lines from neutral or singly ionized Xe atoms in the energy region of 8.4-10.7 eV. The photon flux of the strongest Xe I resonance line at 8.437 eV is comparable to that of the He Ialpha line (21.218 eV) from the He-ECR discharge lamp. Stable operation for more than 300 h is achieved by efficient air-cooling of a ceramic tube in the resonance cavity. The high bulk sensitivity and high-energy resolution of PES using the Xe lines are demonstrated for some typical materials.

SU-F-J-178: A Computer Simulation Model Observer for Task-Based Image Quality Assessment in Radiation Therapy

International Nuclear Information System (INIS)

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

INTERACTION OF LASER RADIATION WITH MATTER: Influence of Ca and Pb impurities on the bulk optical strength of ultrapure NaCl and KCl crystals

Science.gov (United States)

Vinogradov, An V.; Voszka, R.; Kovalev, Valerii I.; Faĭzullov, F. S.; Janszky, J.

1987-06-01

A significant increase (by a factor of about 3) of the bulk damage threshold in the case of interaction of CO2 laser radiation pulses with ultrapure NaCl and KCl crystals grown in a reactive atmosphere was observed on introduction of divalent metal ions Ca and Pb in concentrations of 10-5-10-6 mol/mol. Impurities were introduced in concentrations of 10-8-10-3 and 2×10-7-10-4 mol/mol into the melts of KCl and NaCl, respectively. The concentration of other impurities (including OH) did not exceed ~10-6 mol/mol. A physical model was developed to account for the observed dependence on the basis of an analogy between a system of colloidal particles and F centers in a crystal and a liquid-vapor system.

EUMENES, a computer software for managing the radiation safety program information at an institutional level

International Nuclear Information System (INIS)

Hernandez Saiz, Alejandro; Cornejo Diaz, Nestor; Valdes Ramos, Maryzury; Martinez Gonzalez, Alina; Gonzalez Rodriguez, Niurka; Vergara Gil, Alex

2008-01-01

The correct application of national and international regulations in the field of Radiological Safety requires the implementation of Radiation Safety Programs appropriate to the developed practice. These Programs demand the preparation and keeping of an important number of records and data, the compliance with working schedules, systematic quality controls, audits, delivery of information to the Regulatory Authority, the execution of radiological assessments, etc. Therefore, it is unquestionable the necessity and importance of having a computer tool to support the management of the information related to the Radiation Safety Program in any institution. The present work describes a computer program that allows the efficient management of these data. Its design was based on the IAEA International Basic Safety Standards recommendations and on the requirements of the Cuban national standards, with the objective of being flexible enough to be applied in most of the institutions using ionizing radiations. The most important records of Radiation Safety Programs were incorporated and reports can be generated by the users. An additional tools-module allows the user to access to a radionuclide data library, and to carry out different calculations of interest in radiological protection. The program has been developed in Borland Delphi and manages Microsoft Access databases. It is a user friendly code that aims to support the optimization of Radiation Safety Programs. The program contributes to save resources and time, as the generated information is electronically kept and transmitted. The code has different security access levels according to the user responsibility at the institution and also provides for the analysis of the introduced data, in a quick and efficient way, as well as to notice deadlines, the exceeding of reference levels and situations that require attention. (author)

Computer controlled vacuum control system for synchrotron radiation beam lines

International Nuclear Information System (INIS)

Goldberg, S.M.; Wang, C.; Yang, J.

1983-01-01

The increasing number and complexity of vacuum control systems at the Stanford Synchrotron Radiation Laboratory has resulted in the need to computerize its operations in order to lower costs and increase efficiency of operation. Status signals are transmitted through digital and analog serial data links which use microprocessors to monitor vacuum status continuously. Each microprocessor has a unique address and up to 256 can be connected to the host computer over a single RS232 data line. A FORTRAN program on the host computer will request status messages and send control messages via only one RS232 line per beam line, signal the operator when a fault condition occurs, take automatic corrective actions, warn of impending valve failure, and keep a running log of all changes in vacuum status for later recall. Wiring costs are thus greatly reduced and more status conditions can be monitored without adding excessively to the complexity of the system. Operators can then obtain status reports at various locations in the lab quickly without having to read a large number of meter and LED's

Computer simulation of auroral kilometric radiation

International Nuclear Information System (INIS)

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

Dynamics of charged bulk viscous collapsing cylindrical source with heat flux

Energy Technology Data Exchange (ETDEWEB)

Shah, S.M.; Abbas, G. [The Islamia University of Bahawalpur, Department of Mathematics, Bahawalpur (Pakistan)

2017-04-15

In this paper, we have explored the effects of dissipation on the dynamics of charged bulk viscous collapsing cylindrical source which allows the out-flow of heat flux in the form of radiations. The Misner-Sharp formalism has been implemented to drive the dynamical equation in terms of proper time and radial derivatives. We have investigated the effects of charge and bulk viscosity on the dynamics of collapsing cylinder. To determine the effects of radial heat flux, we have formulated the heat transport equations in the context of Mueller-Israel-Stewart theory by assuming that thermodynamics viscous/heat coupling coefficients can be neglected within some approximations. In our discussion, we have introduced the viscosity by the standard (non-causal) thermodynamics approach. The dynamical equations have been coupled with the heat transport equation; the consequences of the resulting coupled heat equation have been analyzed in detail. (orig.)

Comparison between bulk and thin foil ion irradiation of ultra high purity Fe

Energy Technology Data Exchange (ETDEWEB)

Prokhodtseva, A., E-mail: anna.prokhodtseva@psi.ch [Ecole Polytechnique Fédérale de Lausanne (EPFL), Centre de Recherches en Physique des Plasmas, Association Euratom-Confédération Suisse, 5232 Villigen PSI (Switzerland); Décamps, B. [Centre de Spectrométrie Nucléaire et de Spectrométrie de Masse (CSNSM), CNRS-IN2P3-Univ. Paris-Sud 11, UMR 8609, Bât. 108, 91405 Orsay (France); Schäublin, R. [Ecole Polytechnique Fédérale de Lausanne (EPFL), Centre de Recherches en Physique des Plasmas, Association Euratom-Confédération Suisse, 5232 Villigen PSI (Switzerland)

2013-11-15

Accumulation of radiation damage in ultra high purity iron under self ion irradiation without and with simultaneous He implantation was investigated in bulk and thin foil form to assess, on the one hand, the effect of free surfaces and, on the other hand, the influence of He. Specimens were irradiated at room temperature to a dose of 0.8 dpa and ∼900 appm He content. We found in thin foils after irradiation with single beam a majority of a{sub 0} 〈1 0 0〉 type loops, while in the presence of He it is the ½ a{sub 0} 〈1 1 1〉 type loops that prevail. In single beam irradiated bulk samples most of the loops are of ½ a{sub 0} 〈1 1 1〉 type. In both bulk and thin foils density of defects visible in transmission electron microscope is considerably higher when He is implanted with prevailing ½ a{sub 0} 〈1 1 1〉 dislocation loops, indicating that He stabilizes them.

Investigation of epitaxial silicon layers as a material for radiation hardened silicon detectors

International Nuclear Information System (INIS)

Li, Z.; Eremin, V.; Ilyashenko, I.; Ivanov, A.; Verbitskaya, E.

1997-12-01

Epitaxial grown thick layers (≥ 100 micrometers) of high resistivity silicon (Epi-Si) have been investigated as a possible candidate of radiation hardened material for detectors for high-energy physics. As grown Epi-Si layers contain high concentration (up to 2 x 10 12 cm -3 ) of deep levels compared with that in standard high resistivity bulk Si. After irradiation of test diodes by protons (E p = 24 GeV) with a fluence of 1.5 x 10 11 cm -2 , no additional radiation induced deep traps have been detected. A reasonable explanation is that there is a sink of primary radiation induced defects (interstitial and vacancies), possibly by as-grown defects, in epitaxial layers. The ''sinking'' process, however, becomes non-effective at high radiation fluences (10 14 cm -2 ) due to saturation of epitaxial defects by high concentration of radiation induced ones. As a result, at neutron fluence of 1 x 10 14 cm -2 the deep level spectrum corresponds to well-known spectrum of radiation induced defects in high resistivity bulk Si. The net effective concentration in the space charge region equals to 3 x 10 12 cm -3 after 3 months of room temperature storage and reveals similar annealing behavior for epitaxial as compared to bulk silicon

Hawking radiation and quantum anomaly in AdS2/CFT1 correspondence

International Nuclear Information System (INIS)

Morita, Takeshi

2009-01-01

In order to understand a boundary description of Hawking radiation in the AdS/CFT correspondence, we investigate the trace anomaly method in AdS 2 space. In this method, Hawking radiation is derived from the trace anomaly of the energy-momentum tensor in the bulk. We find a correspondence between the energy-momentum tensor and a composite operator in CFT 1 and understand the anomalous properties of the energy-momentum tensor in terms of this composite operator. By using this correspondence, we reproduce Hawking radiation from the boundary description. In addition, we find a correspondence between higher-spin currents in the bulk and composite operators in the boundary.

Bulk-compositional changes of Ni2Al3 and NiAl3 during ion etching

International Nuclear Information System (INIS)

Chen Houwen; Wang Rong

2008-01-01

Bulk-compositional changes of Ni 2 Al 3 and NiAl 3 in a Ni-50 wt% Al alloy during ion etching have been investigated by transmission electron microscopy and energy dispersive X-ray spectroscopic analyses. After etching with 7, 5 and 3 keV Ar + ions for 15, 24 and 100 h nickel contents in both Ni 2 Al 3 and NiAl 3 exceeded greatly those in the initial compounds and increased with the decrement of the sputtering energy. After 100 h etching with 3 keV Ar + ions the compositions of these two compounds reached a similar value, about Ni 80-83 Al 12-15 Fe 3-4 Cr 1-2 (at%). A synergistic action of preferential sputtering, radiation-induced segregation and radiation-enhanced diffusion enables the altered-layers at the top and bottom of the film extend through the whole film. The bulk-compositional changes are proposed to occur in the unsteady-state sputtering regime of ion etching and caused by an insufficient supply of matter in a thin film

Microhardness of bulk-fill composite materials

OpenAIRE

Kelić, Katarina; Matić, Sanja; Marović, Danijela; Klarić, Eva; Tarle, Zrinka

2016-01-01

The aim of the study was to determine microhardness of high- and low-viscosity bulk-fill composite resins and compare it with conventional composite materials. Four materials of high-viscosity were tested, including three bulk-fills: QuiXfi l (QF), x-tra fil (XTF) and Tetric EvoCeram Bulk Fill (TEBCF), while nanohybrid composite GrandioSO (GSO) served as control. The other four were low-viscosity composites, three bulk-fill materials: Smart Dentin Replacement (SDR), Venus Bulk Fill (VBF) and ...

Internal radiation dose calculations with the INREM II computer code

International Nuclear Information System (INIS)

Dunning, D.E. Jr.; Killough, G.G.

1978-01-01

A computer code, INREM II, was developed to calculate the internal radiation dose equivalent to organs of man which results from the intake of a radionuclide by inhalation or ingestion. Deposition and removal of radioactivity from the respiratory tract is represented by the Internal Commission on Radiological Protection Task Group Lung Model. A four-segment catenary model of the gastrointestinal tract is used to estimate movement of radioactive material that is ingested, or swallowed after being cleared from the respiratory tract. Retention of radioactivity in other organs is specified by linear combinations of decaying exponential functions. The formation and decay of radioactive daughters is treated explicitly, with each radionuclide in the decay chain having its own uptake and retention parameters, as supplied by the user. The dose equivalent to a target organ is computed as the sum of contributions from each source organ in which radioactivity is assumed to be situated. This calculation utilizes a matrix of dosimetric S-factors (rem/μCi-day) supplied by the user for the particular choice of source and target organs. Output permits the evaluation of components of dose from cross-irradiations when penetrating radiations are present. INREM II has been utilized with current radioactive decay data and metabolic models to produce extensive tabulations of dose conversion factors for a reference adult for approximately 150 radionuclides of interest in environmental assessments of light-water-reactor fuel cycles. These dose conversion factors represent the 50-year dose commitment per microcurie intake of a given radionuclide for 22target organs including contributions from specified source organs and surplus activity in the rest of the body. These tabulations are particularly significant in their consistent use of contemporary models and data and in the detail of documentation

Temperature-based estimation of global solar radiation using soft computing methodologies

Science.gov (United States)

Mohammadi, Kasra; Shamshirband, Shahaboddin; Danesh, Amir Seyed; Abdullah, Mohd Shahidan; Zamani, Mazdak

2016-07-01

Precise knowledge of solar radiation is indeed essential in different technological and scientific applications of solar energy. Temperature-based estimation of global solar radiation would be appealing owing to broad availability of measured air temperatures. In this study, the potentials of soft computing techniques are evaluated to estimate daily horizontal global solar radiation (DHGSR) from measured maximum, minimum, and average air temperatures ( T max, T min, and T avg) in an Iranian city. For this purpose, a comparative evaluation between three methodologies of adaptive neuro-fuzzy inference system (ANFIS), radial basis function support vector regression (SVR-rbf), and polynomial basis function support vector regression (SVR-poly) is performed. Five combinations of T max, T min, and T avg are served as inputs to develop ANFIS, SVR-rbf, and SVR-poly models. The attained results show that all ANFIS, SVR-rbf, and SVR-poly models provide favorable accuracy. Based upon all techniques, the higher accuracies are achieved by models (5) using T max- T min and T max as inputs. According to the statistical results, SVR-rbf outperforms SVR-poly and ANFIS. For SVR-rbf (5), the mean absolute bias error, root mean square error, and correlation coefficient are 1.1931 MJ/m2, 2.0716 MJ/m2, and 0.9380, respectively. The survey results approve that SVR-rbf can be used efficiently to estimate DHGSR from air temperatures.

Radiation dose of cone-beam computed tomography compared to conventional radiographs in orthodontics.

Science.gov (United States)

Signorelli, Luca; Patcas, Raphael; Peltomäki, Timo; Schätzle, Marc

2016-01-01

The aim of this study was to determine radiation doses of different cone-beam computed tomography (CBCT) scan modes in comparison to a conventional set of orthodontic radiographs (COR) by means of phantom dosimetry. Thermoluminescent dosimeter (TLD) chips (3 × 1 × 1 mm) were used on an adult male tissue-equivalent phantom to record the distribution of the absorbed radiation dose. Three different scanning modes (i.e., portrait, normal landscape, and fast scan landscape) were compared to CORs [i.e., conventional lateral (LC) and posteroanterior (PA) cephalograms and digital panoramic radiograph (OPG)]. The following radiation levels were measured: 131.7, 91, and 77 μSv in the portrait, normal landscape, and fast landscape modes, respectively. The overall effective dose for a COR was 35.81 μSv (PA: 8.90 μSv; OPG: 21.87 μSv; LC: 5.03 μSv). Although one CBCT scan may replace all CORs, one set of CORs still entails 2-4 times less radiation than one CBCT. Depending on the scan mode, the radiation dose of a CBCT is about 3-6 times an OPG, 8-14 times a PA, and 15-26 times a lateral LC. Finally, in order to fully reconstruct cephalograms including the cranial base and other important structures, the CBCT portrait mode must be chosen, rendering the difference in radiation exposure even clearer (131.7 vs. 35.81 μSv). Shielding radiation-sensitive organs can reduce the effective dose considerably. CBCT should not be recommended for use in all orthodontic patients as a substitute for a conventional set of radiographs. In CBCT, reducing the height of the field of view and shielding the thyroid are advisable methods and must be implemented to lower the exposure dose.

COMPUTATIONAL FLOW MODELLING OF FORMULA-SAE SIDEPODS FOR OPTIMUM RADIATOR HEAT MANAGEMENT

Directory of Open Access Journals (Sweden)

C. M. DE SILVA

2011-02-01

Full Text Available Formula SAE vehicles, over the program’s history have showcased a myriad of aerodynamic packages, each claiming specific quantitative and qualitative features. This paper attempts to critique differing aerodynamic sidepod designs and their effect upon radiator heat management. Various features from inlet size, sidepod shape and size, presence of an undertray, suspension cover, gills and chimneys are analysed for their effects. Computational Fluid Dynamics (CFD analyses are performed in the FLUENT environment, with the aid of GAMBIT meshing software and SolidWorks modelling.

The radiation protective devices for interventional procedures using computed tomography

International Nuclear Information System (INIS)

Iida, Hiroji; Chabatake, Mitsuhiro; Shimizu, Mitsuru; Tamura, Sakio

2002-01-01

A scattered dose and a surface dose from phantom measurements during interventional procedures with computed tomography (IVR-CT) were evaluated. To reduce the personnel exposure in IVR-CT, the new protective devices were developed and its effect evaluated. Two radiation protection devices were experimentally made using a lead vinyl sheet with lead equivalent 0.125 mmPb. The first device is a lead curtain which shields the space of CT-gantry and phantom for the CT examination. The second device is a lead drape which shields on the phantom surface adjacent to the scanning plane for the CT-fluoroscopy. Scattered dose and phantom surface dose were measured with an abdominal phantom during Cine-CT (130 kV, 150 mA, 5 seconds, 10 mm section thickness). They were measured by using ionization chamber dosimeter. They were measured with and without a lead curtain and a lead drape. Scattered dose rate was measured at distance of 50-150 cm from the scanning plane. And, surface dose was measured at distance of 4-21 cm from the scanning plane on the phantom. On operator's standing position, scattered dose rates were from 8.4 to 11.6 μGy/sec at CT examination. The lead curtain and the lead drape reduced scattered dose rate at distance of 50 cm from the scanning plane by 66% and 58.3% respectively. Surface dose rate were 118 μGy/sec at distance of 5 cm from the scanning plane at CT-fluoroscopy. The lead drape reduced the surface dose by 60.5%. High scattered exposure to personnel may occur during interventional procedures using CT. They were considerably reduced during CT-arteriography by attaching the lead curtain in CT equipment. And they were substantially reduced during CT-fluoroscopy by placing the lead drape adjacent to the scanning plane, in addition, operator's hand would be protected from unnecessary radiation scattered by phantom. It was suggested that the scattered exposure to personnel could be sufficiently reduced by using radiation protection devices in IVR-CT. The

Computer modelling of radiation-induced bystander effect

International Nuclear Information System (INIS)

Khvostunov, Igor K.; Nikjoo, Hooshang

2002-01-01

Radiation-induced genomic instability and bystander effects are now well established consequences of exposure of living cells to ionising radiation. It has been observed that cells not directly hit by radiation tracks may still exhibit radiation effects. We present a quantitative modelling of the radiation-induced bystander effect based on a diffusion model of spreading the bystander signal. The model assumes the bystander factor to be a protein of low molecular weight, given out by the hit cell, diffusing in the medium and reacting with non-hit cells. The model calculations successfully predict the results of cell survival in an irradiated conditioned medium. The model predicts the shape of dose-effect relationship for cell survival and oncogenic transformation induced by broad-beam and micro-beam irradiation by alpha-particles. (author)

Mechanism and computational model for Lyman-α-radiation generation by high-intensity-laser four-wave mixing in Kr-Ar gas

Science.gov (United States)

Louchev, Oleg A.; Bakule, Pavel; Saito, Norihito; Wada, Satoshi; Yokoyama, Koji; Ishida, Katsuhiko; Iwasaki, Masahiko

2011-09-01

We present a theoretical model combined with a computational study of a laser four-wave mixing process under optical discharge in which the non-steady-state four-wave amplitude equations are integrated with the kinetic equations of initial optical discharge and electron avalanche ionization in Kr-Ar gas. The model is validated by earlier experimental data showing strong inhibition of the generation of pulsed, tunable Lyman-α (Ly-α) radiation when using sum-difference frequency mixing of 212.6 nm and tunable infrared radiation (820-850 nm). The rigorous computational approach to the problem reveals the possibility and mechanism of strong auto-oscillations in sum-difference resonant Ly-α generation due to the combined effect of (i) 212.6-nm (2+1)-photon ionization producing initial electrons, followed by (ii) the electron avalanche dominated by 843-nm radiation, and (iii) the final breakdown of the phase matching condition. The model shows that the final efficiency of Ly-α radiation generation can achieve a value of ˜5×10-4 which is restricted by the total combined absorption of the fundamental and generated radiation.

Mechanism and computational model for Lyman-{alpha}-radiation generation by high-intensity-laser four-wave mixing in Kr-Ar gas

Energy Technology Data Exchange (ETDEWEB)

Louchev, Oleg A.; Saito, Norihito; Wada, Satoshi [Advanced Science Institute, RIKEN, 2-1 Hirosawa, Wako, Saitama, 351-0198 (Japan); Bakule, Pavel [STFC, ISIS Facility, Rutherford Appleton Laboratory, Chilton, Oxfordshire OX11 0QX (United Kingdom); Yokoyama, Koji [Advanced Science Institute, RIKEN, 2-1 Hirosawa, Wako, Saitama, 351-0198 (Japan); Advanced Meson Science Laboratory, RIKEN Nishina Center, RIKEN, Wako, Saitama 351-0198 (Japan); Ishida, Katsuhiko; Iwasaki, Masahiko [Advanced Meson Science Laboratory, RIKEN Nishina Center, RIKEN, Wako, Saitama 351-0198 (Japan)

2011-09-15

We present a theoretical model combined with a computational study of a laser four-wave mixing process under optical discharge in which the non-steady-state four-wave amplitude equations are integrated with the kinetic equations of initial optical discharge and electron avalanche ionization in Kr-Ar gas. The model is validated by earlier experimental data showing strong inhibition of the generation of pulsed, tunable Lyman-{alpha} (Ly-{alpha}) radiation when using sum-difference frequency mixing of 212.6 nm and tunable infrared radiation (820-850 nm). The rigorous computational approach to the problem reveals the possibility and mechanism of strong auto-oscillations in sum-difference resonant Ly-{alpha} generation due to the combined effect of (i) 212.6-nm (2+1)-photon ionization producing initial electrons, followed by (ii) the electron avalanche dominated by 843-nm radiation, and (iii) the final breakdown of the phase matching condition. The model shows that the final efficiency of Ly-{alpha} radiation generation can achieve a value of {approx}5x10{sup -4} which is restricted by the total combined absorption of the fundamental and generated radiation.

Eurotherm Conference No. 105: Computational Thermal Radiation in Participating Media V

International Nuclear Information System (INIS)

Hafi, Mouna El; Fournier, Richard; Lemonnier, Denis; Lybaert, Paul; Selçuk, Nevin

2016-01-01

This volume of Journal of Physics: Conference Series is based on papers presented at the Eurotherm Conference 105: Computational Thermal Radiation in Participating Media V, which was held in Albi, France on 1-3 April 2015. This seminar was the fifth in a series after Nancy, France (Eurotherm Seminar 95, April 2012), Mons, Belgium (Eurotherm Seminar 73, April 2003), Poitiers, France (Eurotherm Seminar 78, April 2006) and Lisbon, Portugal (Eurotherm Seminar 83, April 2009). Around 40 contributions were received during the conference preparation that have been submitted to oral presentations. A selection process based on two peer-reviews of the full papers finally resulted in the acceptance of 36 for oral presentations (including 2 plenary lectures). These 2 plenary lectures and 10 other papers have been selected for a special issue in a journal related to radiative heat transfer and will not be presented in this volume. The conference was attended by almost 60 scientists from 15 different countries: Australia, Belgium, Canada, China, France, Germany, Poland, Portugal, Russia, Switzerland, The Netherlands, Sweden, Tunisia, Turkey and USA. (paper)

Power balance in ELMO Bumpy Torus: bulk electrons and ions in a 37 kW discharge

International Nuclear Information System (INIS)

McNeill, D.H.

1985-10-01

The power balance of the bulk electrons and ions in discharges with 37 kW of applied microwave power in the ELMO Bumpy Torus (EBT) is examined in a zero-dimensional model using data on the intensity and linewidth of the molecular and atomic hydrogen emission. At least 60% of the applied power is ultimately dissipated by processes involving the neutral particles, including dissociation of molecules, ionization of and radiation from atoms, and heating of cold electrons produced during atomic ionization. The molecular influx rate and the density of atoms are used independently to determine the bulk electron particle confinement time, and an upper bound estimate is made of the diffusional power loss from the bulk plasma electrons. Parameters derived from the basic spectroscopic data presented in this paper include the neutral atom density 2 - 5x10 10 cm -3 , incident molecular flux 3 - 5x10 15 cm -2 s -1 , bulk ion temperature approx. =3 eV, and particle confinement time <1.1 ms. The bulk electron energy confinement time is 0.7 ms or less in the standard operating regime. Published data on the nonthermal electron and ion populations in the plasma are used to evaluate approximately the overall energy flow in the discharge. 54 refs

Mesoscale structural characterization within bulk materials by high-energy X-ray microdiffraction

DEFF Research Database (Denmark)

Lienert, U.; Poulsen, H.F.; Kvick, Å.

2001-01-01

A novel diffraction technique for the local three-dimensional characterization within polycrystalline bulk materials is presented. The technique uses high-energy synchrotron radiation (40 keV materials. Focusing broadband optics have been developed...... experimental evidence that a longitudinal resolution down to 10 mum can be obtained. Fundamental materials properties such as the strain/stress state, grain-orientation, -size, and -surface topology can be probed and mapped in three dimensions in favorable cases. Imbedded volumes and interfaces become...... accessible. The technique is nondestructive and allows for in situ studies of samples in complicated environments. A dedicated experimental station has been constructed at the ID11 beamline of the European Synchrotron Radiation Facility. On-line two-dimensional detectors and conical slits have been developed...

Large area bulk superconductors

Science.gov (United States)

Miller, Dean J.; Field, Michael B.

2002-01-01

A bulk superconductor having a thickness of not less than about 100 microns is carried by a polycrystalline textured substrate having misorientation angles at the surface thereof not greater than about 15.degree.; the bulk superconductor may have a thickness of not less than about 100 microns and a surface area of not less than about 50 cm.sup.2. The textured substrate may have a thickness not less than about 10 microns and misorientation angles at the surface thereof not greater than about 15.degree.. Also disclosed is a process of manufacturing the bulk superconductor and the polycrystalline biaxially textured substrate material.

Field oxide radiation damage measurements in silicon strip detectors

Energy Technology Data Exchange (ETDEWEB)

Laakso, M [Particle Detector Group, Fermilab, Batavia, IL (United States) Research Inst. for High Energy Physics (SEFT), Helsinki (Finland); Singh, P; Shepard, P F [Dept. of Physics and Astronomy, Univ. Pittsburgh, PA (United States)

1993-04-01

Surface radiation damage in planar processed silicon detectors is caused by radiation generated holes being trapped in the silicon dioxide layers on the detector wafer. We have studied charge trapping in thick (field) oxide layers on detector wafers by irradiating FOXFET biased strip detectors and MOS test capacitors. Special emphasis was put on studying how a negative bias voltage across the oxide during irradiation affects hole trapping. In addition to FOXFET biased detectors, negatively biased field oxide layers may exist on the n-side of double-sided strip detectors with field plate based n-strip separation. The results indicate that charge trapping occurred both close to the Si-SiO[sub 2] interface and in the bulk of the oxide. The charge trapped in the bulk was found to modify the electric field in the oxide in a way that leads to saturation in the amount of charge trapped in the bulk when the flatband/threshold voltage shift equals the voltage applied over the oxide during irradiation. After irradiation only charge trapped close to the interface is annealed by electrons tunneling to the oxide from the n-type bulk. (orig.).

Radiation transport and shielding information, computer codes, and nuclear data for use in CTR neutronics research and development

International Nuclear Information System (INIS)

Santoro, R.T.; Maskewitz, B.F.; Roussin, R.W.; Trubey, D.K.

1976-01-01

The activities of the Radiation Shielding Information Center (RSIC) of the Oak Ridge National Laboratory are being utilized in support of fusion reactor technology. The major activities of RSIC include the operation of a computer-based information storage and retrieval system, the collection, packaging, and distribution of large computer codes, and the compilation and dissemination of processed and evaluated data libraries, with particular emphasis on neutron and gamma-ray cross-section data. The Center has acquired thirteen years of experience in serving fission reactor, weapons, and accelerator shielding research communities, and the extension of its technical base to fusion reactor research represents a logical progression. RSIC is currently working with fusion reactor researchers and contractors in computer code development to provide tested radiation transport and shielding codes and data library packages. Of significant interest to the CTR community are the 100 energy group neutron and 21 energy group gamma-ray coupled cross-section data package (DLC-37) for neutronics studies, a comprehensive 171 energy group neutron and 36 energy group gamma-ray coupled cross-section data base with retrieval programs, including resonance self-shielding, that are tailored to CTR application, and a data base for the generation of energy-dependent atomic displacement and gas production cross sections and heavy-particle-recoil spectra for estimating radiation damage to CTR structural components

RADCHARM++: A C++ routine to compute the electromagnetic radiation generated by relativistic charged particles in crystals and complex structures

Energy Technology Data Exchange (ETDEWEB)

Bandiera, Laura; Bagli, Enrico; Guidi, Vincenzo [INFN Sezione di Ferrara and Dipartimento di Fisica e Scienze della Terra, Università degli Studi di Ferrara, Via Saragat 1, 44121 Ferrara (Italy); Tikhomirov, Victor V. [Research Institute for Nuclear Problems, Belarusian State University, Minsk (Belarus)

2015-07-15

The analytical theories of coherent bremsstrahlung and channeling radiation well describe the process of radiation generation in crystals under some special cases. However, the treatment of complex situations requires the usage of a more general approach. In this report we present a C++ routine, named RADCHARM++, to compute the electromagnetic radiation emitted by electrons and positrons in crystals and complex structures. In the RADCHARM++ routine, the model for the computation of e.m. radiation generation is based on the direct integration of the quasiclassical formula of Baier and Katkov. This approach allows one taking into account real trajectories, and thereby the contribution of incoherent scattering. Such contribution can be very important in many cases, for instance for electron channeling. The generality of the Baier–Katkov operator method permits one to simulate the electromagnetic radiation emitted by electrons/positrons in very different cases, e.g., in straight, bent and periodically bent crystals, and for different beam energy ranges, from sub-GeV to TeV and above. The RADCHARM++ routine has been implemented in the Monte Carlo code DYNECHARM++, which solves the classical equation of motion of charged particles traveling through a crystal under the continuum potential approximation. The code has proved to reproduce the results of experiments performed at the MAinzer MIkrotron (MAMI) with 855 MeV electrons and has been used to predict the radiation spectrum generated by the same electron beam in a bent crystal.

A computer database system to calculate staff radiation doses and maintain records

International Nuclear Information System (INIS)

Clewer, P.

1985-01-01

A database has been produced to record the personal dose records of all employees monitored for radiation exposure in the Wessex Health Region. Currently there are more than 2000 personnel in 115 departments but the capacity of the database allows for expansion. The computer is interfaced to a densitometer for film badge reading. The hardware used by the database, which is based on a popular microcomputer, is described, as are the various programs that make up the software. The advantages over the manual card index system that it replaces are discussed. (author)

Radiation doses to patients receiving computed tomography examinations in British Columbia

International Nuclear Information System (INIS)

Aldrich, J.E.; Bilawich, A.-M.; Mayo, J.R.

2006-01-01

To estimate the diagnostic reference levels and effective radiation dose to patients from routine computed tomography (CT) examinations in the province of British Columbia, Canada. The patient weight, height and computed tomography dose index or dose linear product (DLP) were recorded on study sheets for 1070 patients who were referred for clinically indicated routine CT examinations at 18 radiology departments in British Columbia. Sixteen of the scanners were multidetector row scanners. The average patient dose varied from hospital to hospital. The largest range was found for CT of the abdomen, for which the dose varied from 3.6 to 26.5 (average 10.1) mSv. For head CT, the range was 1.7 to 4.9 (average 2.8) mSv; for chest CT, it was 3.8 to 26 (average 9.3) mSv; for pelvis CT, it was 3.5 to 15.5 (average 9.0) mSv; and for abdomen/pelvis CT, it was 7.3 to 31.5 (average 16.3) mSv. Reference dose values were calculated for each exam. These DLP values are as follows: head, 1300 mGy cm; chest, 600 mGy cm; abdomen, 920 mGy cm; pelvis, 650 mGy cm; and abdomen/pelvis, 1100 mGy cm. Among hospitals, there was considerable variation in the DLP and patient radiation dose for a specific exam. Reference doses and patient doses were higher than those found in similar recent surveys carried out in the United Kingdom and the European Union. Patient doses were similar to those found in a recent survey in Germany. (author)

Estimates of radiation over clouds and dust aerosols: Optimized number of terms in phase function expansion

International Nuclear Information System (INIS)

Ding Shouguo; Xie Yu; Yang Ping; Weng Fuzhong; Liu Quanhua; Baum, Bryan; Hu Yongxiang

2009-01-01

The bulk-scattering properties of dust aerosols and clouds are computed for the community radiative transfer model (CRTM) that is a flagship effort of the Joint Center for Satellite Data Assimilation (JCSDA). The delta-fit method is employed to truncate the forward peaks of the scattering phase functions and to compute the Legendre expansion coefficients for re-constructing the truncated phase function. Use of more terms in the expansion gives more accurate re-construction of the phase function, but the issue remains as to how many terms are necessary for different applications. To explore this issue further, the bidirectional reflectances associated with dust aerosols, water clouds, and ice clouds are simulated with various numbers of Legendre expansion terms. To have relative numerical errors smaller than 5%, the present analyses indicate that, in the visible spectrum, 16 Legendre polynomials should be used for dust aerosols, while 32 Legendre expansion terms should be used for both water and ice clouds. In the infrared spectrum, the brightness temperatures at the top of the atmosphere are computed by using the scattering properties of dust aerosols, water clouds and ice clouds. Although small differences of brightness temperatures compared with the counterparts computed with 4, 8, 128 expansion terms are observed at large viewing angles for each layer, it is shown that 4 terms of Legendre polynomials are sufficient in the radiative transfer computation at infrared wavelengths for practical applications.

CR-39 and Lexan calibrated as low-LET radiation dosimeter, for three Mexican irradiation facilities

International Nuclear Information System (INIS)

Tavera, L.; Balcazar, M.; Matamoros, H.; Carrasco, H.

2005-01-01

An experimental calibration of two common nuclear track detectors, CR-39 and Lexan, for gamma and electrons radiation, was performed using various irradiation facilities. The dose response was obtained as a function of two parameters, the bulk etch rate and the UV absorbance for a wide dose range from 10 to 1000 kGy. The bulk etch rate sensitivity, for gamma and electrons, in CR-39 detector is higher than for Lexan detector. Lexan has a well-defined UV absorbance spectrum, but presents saturation for doses higher than 500 kGy, the same saturation characteristic is observed for the corresponding bulk etch rate response. For electron and gamma radiation, CR-39 shows a good response for doses from 10 kGy up to 1000 kGy, where data fit well an exponential curve for electrons and a lineal curve for gamma radiation

The use of mobile computed tomography in intensive care: regulatory compliance and radiation protection

International Nuclear Information System (INIS)

Stevens, G C; Rowles, N P; Loader, R; Foy, R T; Barua, N; Williams, A; Palmer, J D

2009-01-01

The use of mobile head computed tomography (CT) equipment in intensive care is of benefit to unstable patients with brain injury. However, ionising radiation in a ward environment presents difficulties due to the necessity to restrict the exposure to staff and members of the public according to regulation 8(1-2) of the Ionising Radiation Regulations 1999. The methodology for enabling the use of a mobile head CT unit in an open ward area is discussed and a practical solution given. This required the reduction in scatter doses through the installation of extra internal and external shielding, and a further reduction in annual scatter dose by restricting the use of the equipment based on a simulation of the annual ward workload.

Kubo formulas for the shear and bulk viscosity relaxation times and the scalar field theory shear τπ calculation

Science.gov (United States)

Czajka, Alina; Jeon, Sangyong

2017-06-01

In this paper we provide a quantum field theoretical study on the shear and bulk relaxation times. First, we find Kubo formulas for the shear and the bulk relaxation times, respectively. They are found by examining response functions of the stress-energy tensor. We use general properties of correlation functions and the gravitational Ward identity to parametrize analytical structures of the Green functions describing both sound and diffusion mode. We find that the hydrodynamic limits of the real parts of the respective energy-momentum tensor correlation functions provide us with the method of computing both the shear and bulk viscosity relaxation times. Next, we calculate the shear viscosity relaxation time using the diagrammatic approach in the Keldysh basis for the massless λ ϕ4 theory. We derive a respective integral equation which enables us to compute η τπ and then we extract the shear relaxation time. The relaxation time is shown to be inversely related to the thermal width as it should be.

Radiation dose management for pediatric cardiac computed tomography: a report from the Image Gently 'Have-A-Heart' campaign.

Science.gov (United States)

Rigsby, Cynthia K; McKenney, Sarah E; Hill, Kevin D; Chelliah, Anjali; Einstein, Andrew J; Han, B Kelly; Robinson, Joshua D; Sammet, Christina L; Slesnick, Timothy C; Frush, Donald P

2018-01-01

Children with congenital or acquired heart disease can be exposed to relatively high lifetime cumulative doses of ionizing radiation from necessary medical imaging procedures including radiography, fluoroscopic procedures including diagnostic and interventional cardiac catheterizations, electrophysiology examinations, cardiac computed tomography (CT) studies, and nuclear cardiology examinations. Despite the clinical necessity of these imaging studies, the related ionizing radiation exposure could pose an increased lifetime attributable cancer risk. The Image Gently "Have-A-Heart" campaign is promoting the appropriate use of medical imaging studies in children with congenital or acquired heart disease while minimizing radiation exposure. The focus of this manuscript is to provide a comprehensive review of radiation dose management and CT performance in children with congenital or acquired heart disease.

Implementation and display of Computer Aided Design (CAD) models in Monte Carlo radiation transport and shielding applications

International Nuclear Information System (INIS)

Burns, T.J.

1994-01-01

An Xwindow application capable of importing geometric information directly from two Computer Aided Design (CAD) based formats for use in radiation transport and shielding analyses is being developed at ORNL. The application permits the user to graphically view the geometric models imported from the two formats for verification and debugging. Previous models, specifically formatted for the radiation transport and shielding codes can also be imported. Required extensions to the existing combinatorial geometry analysis routines are discussed. Examples illustrating the various options and features which will be implemented in the application are presented. The use of the application as a visualization tool for the output of the radiation transport codes is also discussed

Inversion symmetry and bulk Rashba effect in methylammonium lead iodide perovskite single crystals

KAUST Repository

Frohna, Kyle

2018-05-02

Methylammonium lead iodide perovskite (MAPbI3) exhibits long charge carrier lifetimes that are linked to its high efficiency in solar cells. Yet, the mechanisms governing these unusual carrier dynamics are not completely understood. A leading hypothesis-disproved in this work-is that a large, static bulk Rashba effect slows down carrier recombination. Here, using second harmonic generation rotational anisotropy measurements on MAPbI3 crystals, we demonstrate that the bulk structure of tetragonal MAPbI3 is centrosymmetric with I4/mcm space group. Our calculations show that a significant Rashba splitting in the bandstructure requires a non-centrosymmetric lead iodide framework, and that incorrect structural relaxations are responsible for the previously predicted large Rashba effect. The small Rashba splitting allows us to compute effective masses in excellent agreement with experiment. Our findings rule out the presence of a large static Rashba effect in bulk MAPbI3, and our measurements find no evidence of dynamic Rashba effects.

Inversion symmetry and bulk Rashba effect in methylammonium lead iodide perovskite single crystals

KAUST Repository

Frohna, Kyle; Deshpande, Tejas; Harter, John; Peng, Wei; Barker, Bradford A.; Neaton, Jeffrey B.; Louie, Steven G.; Bakr, Osman; Hsieh, David; Bernardi, Marco

2018-01-01

Methylammonium lead iodide perovskite (MAPbI3) exhibits long charge carrier lifetimes that are linked to its high efficiency in solar cells. Yet, the mechanisms governing these unusual carrier dynamics are not completely understood. A leading hypothesis-disproved in this work-is that a large, static bulk Rashba effect slows down carrier recombination. Here, using second harmonic generation rotational anisotropy measurements on MAPbI3 crystals, we demonstrate that the bulk structure of tetragonal MAPbI3 is centrosymmetric with I4/mcm space group. Our calculations show that a significant Rashba splitting in the bandstructure requires a non-centrosymmetric lead iodide framework, and that incorrect structural relaxations are responsible for the previously predicted large Rashba effect. The small Rashba splitting allows us to compute effective masses in excellent agreement with experiment. Our findings rule out the presence of a large static Rashba effect in bulk MAPbI3, and our measurements find no evidence of dynamic Rashba effects.

Computer Based Radiation Protection- A New Cd-Rom

International Nuclear Information System (INIS)

Geringer, T.; Bammer, M.; Ablber, M.

2004-01-01

Within the next few years, there'll be a lot of new challenges required from radiation protection. According to EU regulation[1] and the new austrian radiation protection law [2] regular additional training are requested. Patients protection in diagnostic and therapeutic usage of ionising radiation gains also more and more importance.[3] Not really surprisingly, the general population is definitely highly aware of the risks coming with the usage of radionuclides and x-rays in medicine. Furthermore, the nuclear power plant in Temelin, near the austrian border initiated a lively discussion about risks, necessity and use of ionising radiation in medicine and industry. It turned out to be a really hard job handling these topics in public. A brilliant didactics based on independent information and viewpoints was required. ARC Seibersdorf Research GmbH, represented by the department of medical technical applications and the radiation protection academy, developed an interactive CD-ROM covering several applications: Basics on radiation protection for medical and technical personnel ; preparation for a radiation protection training. Repetition of the main topics for graduates of a radiation protection training. Basics on radiation protection and emergency management for medical staff as well as for the general public. (Author)

WE-AB-303-09: Rapid Projection Computations for On-Board Digital Tomosynthesis in Radiation Therapy

Energy Technology Data Exchange (ETDEWEB)

Iliopoulos, AS; Sun, X [Duke University, Durham, NC (United States); Pitsianis, N [Aristotle University of Thessaloniki (Greece); Duke University, Durham, NC (United States); Yin, FF; Ren, L [Duke University Medical Center, Durham, NC (United States)

2015-06-15

Purpose: To facilitate fast and accurate iterative volumetric image reconstruction from limited-angle on-board projections. Methods: Intrafraction motion hinders the clinical applicability of modern radiotherapy techniques, such as lung stereotactic body radiation therapy (SBRT). The LIVE system may impact clinical practice by recovering volumetric information via Digital Tomosynthesis (DTS), thus entailing low time and radiation dose for image acquisition during treatment. The DTS is estimated as a deformation of prior CT via iterative registration with on-board images; this shifts the challenge to the computational domain, owing largely to repeated projection computations across iterations. We address this issue by composing efficient digital projection operators from their constituent parts. This allows us to separate the static (projection geometry) and dynamic (volume/image data) parts of projection operations by means of pre-computations, enabling fast on-board processing, while also relaxing constraints on underlying numerical models (e.g. regridding interpolation kernels). Further decoupling the projectors into simpler ones ensures the incurred memory overhead remains low, within the capacity of a single GPU. These operators depend only on the treatment plan and may be reused across iterations and patients. The dynamic processing load is kept to a minimum and maps well to the GPU computational model. Results: We have integrated efficient, pre-computable modules for volumetric ray-casting and FDK-based back-projection with the LIVE processing pipeline. Our results show a 60x acceleration of the DTS computations, compared to the previous version, using a single GPU; presently, reconstruction is attained within a couple of minutes. The present implementation allows for significant flexibility in terms of the numerical and operational projection model; we are investigating the benefit of further optimizations and accurate digital projection sub

WE-AB-303-09: Rapid Projection Computations for On-Board Digital Tomosynthesis in Radiation Therapy

International Nuclear Information System (INIS)

Iliopoulos, AS; Sun, X; Pitsianis, N; Yin, FF; Ren, L

2015-01-01

Purpose: To facilitate fast and accurate iterative volumetric image reconstruction from limited-angle on-board projections. Methods: Intrafraction motion hinders the clinical applicability of modern radiotherapy techniques, such as lung stereotactic body radiation therapy (SBRT). The LIVE system may impact clinical practice by recovering volumetric information via Digital Tomosynthesis (DTS), thus entailing low time and radiation dose for image acquisition during treatment. The DTS is estimated as a deformation of prior CT via iterative registration with on-board images; this shifts the challenge to the computational domain, owing largely to repeated projection computations across iterations. We address this issue by composing efficient digital projection operators from their constituent parts. This allows us to separate the static (projection geometry) and dynamic (volume/image data) parts of projection operations by means of pre-computations, enabling fast on-board processing, while also relaxing constraints on underlying numerical models (e.g. regridding interpolation kernels). Further decoupling the projectors into simpler ones ensures the incurred memory overhead remains low, within the capacity of a single GPU. These operators depend only on the treatment plan and may be reused across iterations and patients. The dynamic processing load is kept to a minimum and maps well to the GPU computational model. Results: We have integrated efficient, pre-computable modules for volumetric ray-casting and FDK-based back-projection with the LIVE processing pipeline. Our results show a 60x acceleration of the DTS computations, compared to the previous version, using a single GPU; presently, reconstruction is attained within a couple of minutes. The present implementation allows for significant flexibility in terms of the numerical and operational projection model; we are investigating the benefit of further optimizations and accurate digital projection sub

Bulk viscous corrections to screening and damping in QCD at high temperatures

Energy Technology Data Exchange (ETDEWEB)

Du, Qianqian [Department of Physics, Guangxi Normal University,Guilin, 541004 (China); Dumitru, Adrian [Department of Natural Sciences, Baruch College, CUNY,17 Lexington Avenue, New York, NY 10010 (United States); The Graduate School and University Center, The City University of New York,365 Fifth Avenue, New York, NY 10016 (United States); Guo, Yun [Department of Physics, Guangxi Normal University,Guilin, 541004 (China); Strickland, Michael [Department of Physics, Kent State University,206B Smith Hall, Kent, OH 44240 (United States)

2017-01-27

Non-equilibrium corrections to the distribution functions of quarks and gluons in a hot and dense QCD medium modify the “hard thermal loops” (HTL). The HTLs determine the retarded, advanced, and symmetric (time-ordered) propagators for gluons with soft momenta as well as the Debye screening and Landau damping mass scales. We compute such corrections to a thermal as well as to a non-thermal fixed point. The screening and damping mass scales are sensitive to the bulk pressure and hence to (pseudo-) critical dynamical scaling of the bulk viscosity in the vicinity of a second-order critical point. This could be reflected in the properties of quarkonium bound states in the deconfined phase and in the dynamics of soft gluon fields.

Bulk viscous corrections to screening and damping in QCD at high temperatures

International Nuclear Information System (INIS)

Du, Qianqian; Dumitru, Adrian; Guo, Yun; Strickland, Michael

2017-01-01

Non-equilibrium corrections to the distribution functions of quarks and gluons in a hot and dense QCD medium modify the “hard thermal loops” (HTL). The HTLs determine the retarded, advanced, and symmetric (time-ordered) propagators for gluons with soft momenta as well as the Debye screening and Landau damping mass scales. We compute such corrections to a thermal as well as to a non-thermal fixed point. The screening and damping mass scales are sensitive to the bulk pressure and hence to (pseudo-) critical dynamical scaling of the bulk viscosity in the vicinity of a second-order critical point. This could be reflected in the properties of quarkonium bound states in the deconfined phase and in the dynamics of soft gluon fields.

Computer simulation of threshold radiation damage in rutile, TiO2

International Nuclear Information System (INIS)

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)

Knowledge management: Role of the the Radiation Safety Information Computational Center (RSICC)

Science.gov (United States)

Valentine, Timothy

2017-09-01

The Radiation Safety Information Computational Center (RSICC) at Oak Ridge National Laboratory (ORNL) is an information analysis center that collects, archives, evaluates, synthesizes and distributes information, data and codes that are used in various nuclear technology applications. RSICC retains more than 2,000 software packages that have been provided by code developers from various federal and international agencies. RSICC's customers (scientists, engineers, and students from around the world) obtain access to such computing codes (source and/or executable versions) and processed nuclear data files to promote on-going research, to ensure nuclear and radiological safety, and to advance nuclear technology. The role of such information analysis centers is critical for supporting and sustaining nuclear education and training programs both domestically and internationally, as the majority of RSICC's customers are students attending U.S. universities. Additionally, RSICC operates a secure CLOUD computing system to provide access to sensitive export-controlled modeling and simulation (M&S) tools that support both domestic and international activities. This presentation will provide a general review of RSICC's activities, services, and systems that support knowledge management and education and training in the nuclear field.

Calm water resistance prediction of a bulk carrier using Reynolds averaged Navier-Stokes based solver

Science.gov (United States)

Rahaman, Md. Mashiur; Islam, Hafizul; Islam, Md. Tariqul; Khondoker, Md. Reaz Hasan

2017-12-01

Maneuverability and resistance prediction with suitable accuracy is essential for optimum ship design and propulsion power prediction. This paper aims at providing some of the maneuverability characteristics of a Japanese bulk carrier model, JBC in calm water using a computational fluid dynamics solver named SHIP Motion and OpenFOAM. The solvers are based on the Reynolds average Navier-Stokes method (RaNS) and solves structured grid using the Finite Volume Method (FVM). This paper comprises the numerical results of calm water test for the JBC model with available experimental results. The calm water test results include the total drag co-efficient, average sinkage, and trim data. Visualization data for pressure distribution on the hull surface and free water surface have also been included. The paper concludes that the presented solvers predict the resistance and maneuverability characteristics of the bulk carrier with reasonable accuracy utilizing minimum computational resources.

Photovoltaic characteristics of diffused P/+N bulk GaAs solar cells

Science.gov (United States)

Borrego, J. M.; Keeney, R. P.; Bhat, I. B.; Bhat, K. N.; Sundaram, L. G.; Ghandhi, S. K.

1982-01-01

The photovoltaic characteristics of P(+)N junction solar cells fabricated on bulk GaAs by an open tube diffusion technique are described in this paper.Spectral response measurements were analyzed in detail and compared to a computer simulation in order to determine important material parameters. It is projected that proper optimization of the cell parameters can increase the efficiency of the cells from 12.2 percent to close to 20 percent.

Radiation transport and shielding information, computer codes, and nuclear data for use in CTR neutronics research and development

International Nuclear Information System (INIS)

Santoro, R.T.; Maskewitz, B.F.; Roussin, R.W.; Trubey, D.K.

1976-01-01

The activities of the Radiation Shielding Information Center (RSIC) of the Oak Ridge National Laboratory are being utilized in support of fusion reactor technology. The major activities of RSIC include the operation of a computer-based information storage and retrieval system, the collection, packaging, and distribution of large computer codes, and the compilation and dissemination of processed and evaluated data libraries, with particular emphasis on neutron and gamma-ray cross-section data. The Center has acquired thirteen years of experience in serving fission reactor, weapons, and accelerator shielding research communities, and the extension of its technical base to fusion reactor research represents a logical progression. RSIC is currently working with fusion reactor researchers and contractors in computer code development to provide tested radiation transport and shielding codes and data library packages. Of significant interest to the CTR community are the 100 energy group neutron and 21 energy group gamma-ray coupled cross-section data package (DLC-37) for neutronics studies, a comprehensive 171 energy group neutron and 36 energy group gamma-ray coupled cross-section data base with retrieval programs, including resonance self-shielding, that are tailored to CTR application, and a data base for the generation of energy-dependent atomic displacement and gas production cross sections and heavy-particle-recoil spectra for estimating radiation damage to CTR structural components. Since 1964, the Center has been involved in the international exchange of information, encouraged and supported by both government and interagency agreements; and to achieve an equally viable and successful program in fusion research, the reciprocal exchange of CTR data and computing technology is encouraged and welcomed

Three-dimensional coupled Monte Carlo-discrete ordinates computational scheme for shielding calculations of large and complex nuclear facilities

International Nuclear Information System (INIS)

Chen, Y.; Fischer, U.

2005-01-01

Shielding calculations of advanced nuclear facilities such as accelerator based neutron sources or fusion devices of the tokamak type are complicated due to their complex geometries and their large dimensions, including bulk shields of several meters thickness. While the complexity of the geometry in the shielding calculation can be hardly handled by the discrete ordinates method, the deep penetration of radiation through bulk shields is a severe challenge for the Monte Carlo particle transport technique. This work proposes a dedicated computational scheme for coupled Monte Carlo-Discrete Ordinates transport calculations to handle this kind of shielding problems. The Monte Carlo technique is used to simulate the particle generation and transport in the target region with both complex geometry and reaction physics, and the discrete ordinates method is used to treat the deep penetration problem in the bulk shield. The coupling scheme has been implemented in a program system by loosely integrating the Monte Carlo transport code MCNP, the three-dimensional discrete ordinates code TORT and a newly developed coupling interface program for mapping process. Test calculations were performed with comparison to MCNP solutions. Satisfactory agreements were obtained between these two approaches. The program system has been chosen to treat the complicated shielding problem of the accelerator-based IFMIF neutron source. The successful application demonstrates that coupling scheme with the program system is a useful computational tool for the shielding analysis of complex and large nuclear facilities. (authors)

Radiation sterilization of medical products

International Nuclear Information System (INIS)

Khurshid, S.J.; Hussain, A.M.

1989-01-01

Radiation sterilization is the best method of sterilization, essentially for single use medical and surgical products. Pakistan has established a commercial gamma irradiation plant for this purpose. This article overviews the advantages and benefits of radiation sterilization to stimulate the interest of industrialists and the users in this technology. This technology can give a better medical care in the country and the growing demand can only be met by bulk sterilization. The radiation sterilized medical products can also compete well with the products sterilized by other methods in the international market, gamma sterilization is accepted internationally and if adopted it can boost our export of medical products. (author)

STRAY - An interactive program for the computation of stray radiation in infrared telescopes

Science.gov (United States)

St. Clair Dinger, Ann

1987-01-01

The STRAY program to model the amount of stray radiation reaching the focal plane of a well-baffled telescope is described. The STRAY telescope model is addressed, including the aperture shade, barrel baffle, optics, mirror sectioning and chopping, and off-axis points in focal plane. The possible illumination paths are shown, and calculation options using STRAY are discussed. The stored data and computational aspects of STRAY are addressed. STRAY is compared to the MINI-APART model, and applications of STRAY are described.

Combined effect of bulk and surface damage on strip insulation properties of proton irradiated n$^{+}$-p silicon strip sensors

CERN Document Server

Dalal, R; Ranjan, K; Moll, M; Elliott-Peisert, A

2014-01-01

Silicon sensors in next generation hadron colliders willface a tremendously harsh radiation environment. Requirement tostudy rarest reaction channels with statistical constraints hasresulted in a huge increment in radiation flux, resulting in bothsurface damage and bulk damage. For sensors which are used in acharged hadron environment, both of these degrading processes takeplace simultaneously. Recently it has been observed in protonirradiated n$^{+}$-p Si strip sensors that n$^{+}$ strips had a goodinter-strip insulation with low values of p-spray and p-stop dopingdensities which is contrary to the expected behaviour from thecurrent understanding of radiation damage. In this work a simulationmodel has been devised incorporating radiation damage to understandand provide a possible explanation to the observed behaviour ofirradiated sensors.

Developing bulk exchange spring magnets

Science.gov (United States)

Mccall, Scott K.; Kuntz, Joshua D.

2017-06-27

A method of making a bulk exchange spring magnet by providing a magnetically soft material, providing a hard magnetic material, and producing a composite of said magnetically soft material and said hard magnetic material to make the bulk exchange spring magnet. The step of producing a composite of magnetically soft material and hard magnetic material is accomplished by electrophoretic deposition of the magnetically soft material and the hard magnetic material to make the bulk exchange spring magnet.

In-line bulk supersaturation measurement by electrical conductometry in KDP crystal growth from aqueous solution

Science.gov (United States)

Bordui, P. F.; Loiacono, G. M.

1984-07-01

A method is presented for in-line bulk supersaturation measurement in crystal growth from aqueous solution. The method is based on a computer-controlled concentration measurement exploiting an experimentally predetermined cross-correlation between the concentration, electrical conductivity, and temperature of the growth solution. The method was applied to Holden crystallization of potassium dihydrogen phosphate (KDP). An extensive conductivity-temperature-concentration data base was generated for this system over a temperature range of 31 to 41°C. The method yielded continous, automated bulk supersaturation output accurate to within ±0.05 g KDP100 g water (±0.15% relative supersaturation).

CW frequency doubling of 1029 nm radiation using single pass bulk and waveguide PPLN crystals

Czech Academy of Sciences Publication Activity Database

Chiodo, N.; Du Burck, F.; Hrabina, Jan; Candela, Y.; Wallerand, J. P.; Acef, O.

2013-01-01

Roč. 311, 15 January (2013), s. 239-244 ISSN 0030-4018 R&D Projects: GA ČR GPP102/11/P820 Institutional support: RVO:68081731 Keywords : IR laser * second harmonic generation * waveguide and bulk crystals * periodically poled lithium niobate * 1029 nm wavelength Subject RIV: BH - Optics , Masers, Lasers Impact factor: 1.542, year: 2013

Computational Modeling of Micrometastatic Breast Cancer Radiation Dose Response

Energy Technology Data Exchange (ETDEWEB)

Smith, Daniel L.; Debeb, Bisrat G. [Department of Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas (United States); Morgan Welch Inflammatory Breast Cancer Research Program and Clinic, The University of Texas MD Anderson Cancer Center, Houston, Texas (United States); Thames, Howard D. [Department of Biostatistics, The University of Texas MD Anderson Cancer Center, Houston, Texas (United States); Woodward, Wendy A., E-mail: wwoodward@mdanderson.org [Department of Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas (United States); Morgan Welch Inflammatory Breast Cancer Research Program and Clinic, The University of Texas MD Anderson Cancer Center, Houston, Texas (United States)

2016-09-01

Purpose: Prophylactic cranial irradiation (PCI) involves giving radiation to the entire brain with the goals of reducing the incidence of brain metastasis and improving overall survival. Experimentally, we have demonstrated that PCI prevents brain metastases in a breast cancer mouse model. We developed a computational model to expand on and aid in the interpretation of our experimental results. Methods and Materials: MATLAB was used to develop a computational model of brain metastasis and PCI in mice. Model input parameters were optimized such that the model output would match the experimental number of metastases per mouse from the unirradiated group. An independent in vivo–limiting dilution experiment was performed to validate the model. The effect of whole brain irradiation at different measurement points after tumor cells were injected was evaluated in terms of the incidence, number of metastases, and tumor burden and was then compared with the corresponding experimental data. Results: In the optimized model, the correlation between the number of metastases per mouse and the experimental fits was >95. Our attempt to validate the model with a limiting dilution assay produced 99.9% correlation with respect to the incidence of metastases. The model accurately predicted the effect of whole-brain irradiation given 3 weeks after cell injection but substantially underestimated its effect when delivered 5 days after cell injection. The model further demonstrated that delaying whole-brain irradiation until the development of gross disease introduces a dose threshold that must be reached before a reduction in incidence can be realized. Conclusions: Our computational model of mouse brain metastasis and PCI correlated strongly with our experiments with unirradiated mice. The results further suggest that early treatment of subclinical disease is more effective than irradiating established disease.

Mechanical design engineering. NASA/university advanced design program: Lunar Bulk Material Transport Vehicle

Science.gov (United States)

Daugherty, Paul; Griner, Stewart; Hendrix, Alan; Makarov, Chris; Martiny, Stephen; Meyhoefer, Douglas Ralph; Platt, Cody Claxton; Sivak, John; Wheeler, Elizabeth Fitch

1988-01-01

The design of a Lunar Bulk Material Transport Vehicle (LBMTV) is discussed. Goals set in the project include a payload of 50 cubic feet of lunar soil with a lunar of approximately 800 moon-pounds, a speed of 15 mph, and the ability to handle a grade of 20 percent. Thermal control, an articulated steering mechanism, a dump mechanism, a self-righting mechanism, viable power sources, and a probable control panel are analyzed. The thermal control system involves the use of small strip heaters to heat the housing of electronic equipment in the absence of sufficient solar radiation and multi-layer insulation during periods of intense solar radiation. The entire system uses only 10 W and weighs about 60 pounds, or 10 moon-pounds. The steering mechanism is an articulated steering joint at the center of the vehicle. It utilizes two actuators and yields a turning radius of 10.3 feet. The dump mechanism rotates the bulk material container through an angle of 100 degree using one actuator. The self-righting mechanism consists of two four bar linkages, each of which is powered by the same size actuator as the other linkages. The LBMTV is powered by rechargeable batteries. A running time of at least two hours is attained under a worst case analysis. The weight of the batteries is 100 pounds. A control panel consisting of feedback and control instruments is described. The panel includes all critical information necessary to control the vehicle remotely. The LBMTV is capable of handling many types of cargo. It is able to interface with many types of removable bulk material containers. These containers are made to interface with the three-legged walker, SKITTER. The overall vehicle is about 15 feet in length and has a weight of about 1000 pounds, or 170 lunar pounds.

The cellular environment in computer simulations of radiation-induced damage to DNA

International Nuclear Information System (INIS)

Moiseenko, V.V.; Waker, A.J.; Prestwich, W.V.

1998-01-01

Radiation-induced DNA single- and double-strand breaks were modeled for 660 keV photon radiation and scavenger capacity mimicking the cellular environment. Atomistic representation of DNA in B form with a first hydration shell was utilized to model direct and indirect damage. Monte Carlo generated electron tracks were used to model energy deposition in matter and to derive initial spatial distributions of species which appear in the medium following radiolysis. Diffusion of species was followed with time, and their reactions with DNA and each other were modeled in an encounter-controlled manner. Three methods to account for hydroxyl radical diffusion in a cellular environment were tested: assumed exponential survival, time-limited modeling and modeling of reactions between hydroxyl radicals and scavengers in an encounter-controlled manner. Although the method based on modeling scavenging in an encounter-controlled manner is more precise, it requires substantially more computer resources than either the exponential or time-limiting method. Scavenger concentrations of 0.5 and 0.15 M were considered using exponential and encounter-controlled methods with reaction rate set at 3 x 10 9 dm 3 mol -1 s -1 . Diffusion length and strand break yields, predicted by these two methods for the same scavenger molarity, were different by 20%-30%. The method based on limiting time of chemistry follow-up to 10 -9 s leads to DNA damage and radical diffusion estimates similar to 0.5 M scavenger concentration in the other two methods. The difference observed in predictions made by the methods considered could be tolerated in computer simulations of DNA damage. (orig.)

The cellular environment in computer simulations of radiation-induced damage to DNA

International Nuclear Information System (INIS)

Moiseenko, V.V.; Hamm, R.N.; Waker, A.J.; Prestwich, W.V.

1988-01-01

Radiation-induced DNA single- and double-strand breaks were modeled for 660 keV photon radiation and scavenger capacity mimicking the cellular environment. Atomistic representation of DNA in B form with a first hydration shell was utilized to model direct and indirect damage. Monte Carlo generated electron tracks were used to model energy deposition in matter and to derive initial spatial distributions of species which appear in the medium following radiolysis. Diffusion of species was followed with time, and their reactions with DNA and each other were modeled in an encounter-controlled manner. Three methods to account for hydroxyl radical diffusion in cellular environment were tested: assumed exponential survival, time-limited modeling and modeling of reactions between hydroxyl radicals and scavengers in an encounter-controlled manner. Although the method based on modeling scavenging in an encounter-controlled manner is more precise, it requires substantially more computer resources than either the exponential or time-limiting method. Scavenger concentrations of 0.5 and 0.15 M were considered using exponential and encounter-controlled methods with reaction rate set at 3x10 9 dm 3 mol -1 s-1. Diffusion length and strand break yields, predicted by these two methods for the same scavenger molarity, were different by 20%-30%. The method based on limiting time of chemistry follow-up to 10 -9 s leads to DNA damage and radical diffusion estimates similar to 0.5 M scavenger concentration in the other two methods. The difference observed in predictions made by the methods considered could be tolerated in computer simulations of DNA damage. (author)

Basic principles of medical aid in cases of radiation accidents

International Nuclear Information System (INIS)

Andreev, E.; Mikhajlov, M.A.; Bliznakov, V.

1979-01-01

A model scheme has been presented of medical aid organization in emergency cases of irradiation. The tasks of medical service have been pointed out in connection with evacuation stages, bulk of medical aid depending on the natur of radiation damages, first aid and some general principles of radiation sickness treatment. (author)

Bulk-Flow Analysis of Hybrid Thrust Bearings for Advanced Cryogenic Turbopumps

Science.gov (United States)

SanAndres, Luis

1998-01-01

A bulk-flow analysis and computer program for prediction of the static load performance and dynamic force coefficients of angled injection, orifice-compensated hydrostatic/hydrodynamic thrust bearings have been completed. The product of the research is an efficient computational tool for the design of high-speed thrust bearings for cryogenic fluid turbopumps. The study addresses the needs of a growing technology that requires of reliable fluid film bearings to provide the maximum operating life with optimum controllable rotordynamic characteristics at the lowest cost. The motion of a cryogenic fluid on the thin film lands of a thrust bearing is governed by a set of bulk-flow mass and momentum conservation and energy transport equations. Mass flow conservation and a simple model for momentum transport within the hydrostatic bearing recesses are also accounted for. The bulk-flow model includes flow turbulence with fluid inertia advection, Coriolis and centrifugal acceleration effects on the bearing recesses and film lands. The cryogenic fluid properties are obtained from realistic thermophysical equations of state. Turbulent bulk-flow shear parameters are based on Hirs' model with Moody's friction factor equations allowing a simple simulation for machined bearing surface roughness. A perturbation analysis leads to zeroth-order nonlinear equations governing the fluid flow for the thrust bearing operating at a static equilibrium position, and first-order linear equations describing the perturbed fluid flow for small amplitude shaft motions in the axial direction. Numerical solution to the zeroth-order flow field equations renders the bearing flow rate, thrust load, drag torque and power dissipation. Solution to the first-order equations determines the axial stiffness, damping and inertia force coefficients. The computational method uses well established algorithms and generic subprograms available from prior developments. The Fortran9O computer program hydrothrust runs

Estimation of the radiation exposure of a chest pain protocol with ECG-gating in dual-source computed tomography

International Nuclear Information System (INIS)

Ketelsen, Dominik; Luetkhoff, Marie H.; Thomas, Christoph; Werner, Matthias; Tsiflikas, Ilias; Reimann, Anja; Kopp, Andreas F.; Claussen, Claus D.; Heuschmid, Martin; Buchgeister, Markus; Burgstahler, Christof

2009-01-01

The aim of the study was to evaluate radiation exposure of a chest pain protocol with ECG-gated dual-source computed tomography (DSCT). An Alderson Rando phantom equipped with thermoluminescent dosimeters was used for dose measurements. Exposure was performed on a dual-source computed tomography system with a standard protocol for chest pain evaluation (120 kV, 320 mAs/rot) with different simulated heart rates (HRs). The dose of a standard chest CT examination (120 kV, 160 mAs) was also measured. Effective dose of the chest pain protocol was 19.3/21.9 mSv (male/female, HR 60), 17.9/20.4 mSv (male/female, HR 80) and 14.7/16.7 mSv (male/female, HR 100). Effective dose of a standard chest examination was 6.3 mSv (males) and 7.2 mSv (females). Radiation dose of the chest pain protocol increases significantly with a lower heart rate for both males (p = 0.040) and females (p = 0.044). The average radiation dose of a standard chest CT examination is about 36.5% that of a CT examination performed for chest pain. Using DSCT, the evaluated chest pain protocol revealed a higher radiation exposure compared with standard chest CT. Furthermore, HRs markedly influenced the dose exposure when using the ECG-gated chest pain protocol. (orig.)

Assessment of knowledge and awareness among radiology personnel regarding current computed tomography technology and radiation dose

Science.gov (United States)

Karim, M. K. A.; Hashim, S.; Bradley, D. A.; Bahruddin, N. A.; Ang, W. C.; Salehhon, N.

2016-03-01

In this paper, we evaluate the level of knowledge and awareness among 120 radiology personnel working in 7 public hospitals in Johor, Malaysia, concerning Computed Tomography (CT) technology and radiation doses based on a set of questionnaires. Subjects were divided into two groups (Medical profession (Med, n=32) and Allied health profession (AH, n=88). The questionnaires are addressed: (1) demographic data (2) relative radiation dose and (3) knowledge of current CT technology. One-third of respondents from both groups were able to estimate relative radiation dose for routine CT examinations. 68% of the allied health profession personnel knew of the Malaysia regulations entitled ‘Basic Safety Standard (BSS) 2010’, although notably 80% of them had previously attended a radiation protection course. No significant difference (p < 0.05) in mean scores of CT technology knowledge detected between the two groups, with the medical professions producing a mean score of (26.7 ± 2.7) and the allied health professions a mean score of (25.2 ± 4.3). This study points to considerable variation among the respondents concerning their understanding of knowledge and awareness of risks of radiation and CT optimization techniques.

Assessment of knowledge and awareness among radiology personnel regarding current computed tomography technology and radiation dose

International Nuclear Information System (INIS)

Karim, M K A; Hashim, S; Bahruddin, N A; Ang, W C; Salehhon, N; Bradley, D A

2016-01-01

In this paper, we evaluate the level of knowledge and awareness among 120 radiology personnel working in 7 public hospitals in Johor, Malaysia, concerning Computed Tomography (CT) technology and radiation doses based on a set of questionnaires. Subjects were divided into two groups (Medical profession (Med, n=32) and Allied health profession (AH, n=88). The questionnaires are addressed: (1) demographic data (2) relative radiation dose and (3) knowledge of current CT technology. One-third of respondents from both groups were able to estimate relative radiation dose for routine CT examinations. 68% of the allied health profession personnel knew of the Malaysia regulations entitled ‘Basic Safety Standard (BSS) 2010’, although notably 80% of them had previously attended a radiation protection course. No significant difference (p < 0.05) in mean scores of CT technology knowledge detected between the two groups, with the medical professions producing a mean score of (26.7 ± 2.7) and the allied health professions a mean score of (25.2 ± 4.3). This study points to considerable variation among the respondents concerning their understanding of knowledge and awareness of risks of radiation and CT optimization techniques. (paper)

Modelling of bulk superconductor magnetization

International Nuclear Information System (INIS)

Ainslie, M D; Fujishiro, H

2015-01-01

This paper presents a topical review of the current state of the art in modelling the magnetization of bulk superconductors, including both (RE)BCO (where RE = rare earth or Y) and MgB 2 materials. Such modelling is a powerful tool to understand the physical mechanisms of their magnetization, to assist in interpretation of experimental results, and to predict the performance of practical bulk superconductor-based devices, which is particularly important as many superconducting applications head towards the commercialization stage of their development in the coming years. In addition to the analytical and numerical techniques currently used by researchers for modelling such materials, the commonly used practical techniques to magnetize bulk superconductors are summarized with a particular focus on pulsed field magnetization (PFM), which is promising as a compact, mobile and relatively inexpensive magnetizing technique. A number of numerical models developed to analyse the issues related to PFM and optimise the technique are described in detail, including understanding the dynamics of the magnetic flux penetration and the influence of material inhomogeneities, thermal properties, pulse duration, magnitude and shape, and the shape of the magnetization coil(s). The effect of externally applied magnetic fields in different configurations on the attenuation of the trapped field is also discussed. A number of novel and hybrid bulk superconductor structures are described, including improved thermal conductivity structures and ferromagnet–superconductor structures, which have been designed to overcome some of the issues related to bulk superconductors and their magnetization and enhance the intrinsic properties of bulk superconductors acting as trapped field magnets. Finally, the use of hollow bulk cylinders/tubes for shielding is analysed. (topical review)

First-principles calculations of bulk and interfacial thermodynamic properties for fcc-based Al-Sc alloys

International Nuclear Information System (INIS)

Asta, M.; Foiles, S.M.; Quong, A.A.

1998-01-01

The configurational thermodynamic properties of fcc-based Al-Sc alloys and coherent Al/Al 3 Sc interphase-boundary interfaces have been calculated from first principles. The computational approach used in this study combines the results of pseudopotential total-energy calculations with a cluster-expansion description of the alloy energetics. Bulk and interface configurational-thermodynamic properties are computed using a low-temperature-expansion technique. Calculated values of the {100} and {111} Al/Al 3 Sc interfacial energies at zero temperature are, respectively, 192 and 226mJ/m 2 . The temperature dependence of the calculated interfacial free energies is found to be very weak for {100} and more appreciable for {111} orientations; the primary effect of configurational disordering at finite temperature is to reduce the degree of crystallographic anisotropy associated with calculated interfacial free energies. The first-principles-computed solid-solubility limits for Sc in bulk fcc Al are found to be underestimated significantly in comparison with experimental measurements. It is argued that this discrepancy can be largely attributed to nonconfigurational contributions to the entropy which have been neglected in the present thermodynamic calculations. copyright 1998 The American Physical Society

First-principles studies of electronic, transport and bulk properties of pyrite FeS2

Directory of Open Access Journals (Sweden)

Dipendra Banjara

2018-02-01

Full Text Available We present results from first principle, local density approximation (LDA calculations of electronic, transport, and bulk properties of iron pyrite (FeS2. Our non-relativistic computations employed the Ceperley and Alder LDA potential and the linear combination of atomic orbitals (LCAO formalism. The implementation of the LCAO formalism followed the Bagayoko, Zhao, and Williams (BZW method, as enhanced by Ekuma and Franklin (BZW-EF. We discuss the electronic energy bands, total and partial densities of states, electron effective masses, and the bulk modulus. Our calculated indirect band gap of 0.959 eV (0.96, using an experimental lattice constant of 5.4166 Å, at room temperature, is in agreement with the measured indirect values, for bulk samples, ranging from 0.84 eV to 1.03 ± 0.05 eV. Our calculated bulk modulus of 147 GPa is practically in agreement with the experimental value of 145 GPa. The calculated, partial densities of states reproduced the splitting of the Fe d bands to constitute the dominant upper most valence and lower most conduction bands, separated by the generally accepted, indirect, experimental band gap of 0.95 eV.

Reliability of real-time computing with radiation data feedback at accidental release

International Nuclear Information System (INIS)

Deme, S.; Feher, I.; Lang, E.

1989-07-01

At present, the computing method normalized for the telemetric data represents the primary information for deciding on any necessary countermeasures in case of a nuclear reactor accident. The reliability of the results, however, are influenced by the choice of certain parameters that can not be determined by direct methods. Improperly chosen diffusion parameters would distort the determination of environmental radiation parameters normalized on the basis of the measurements ( 131 I activity concentration, gamma dose rate) at points lying at a given distance from the measuring stations. Numerical examples for the uncertainties due to the above factors are analyzed. (author) 4 refs.; 14 figs

The Role of the Radiation Safety Information Computational Center (RSICC) in Knowledge Management

International Nuclear Information System (INIS)

Valentine, T.

2016-01-01

Full text: The Radiation Safety Information Computational Center (RSICC) is an information analysis center that collects, archives, evaluates, synthesizes and distributes information, data and codes that are used in various nuclear technology applications. RSICC retains more than 2,000 packages that have been provided by contributors from various agencies. RSICC’s customers obtain access to such computing codes (source and/or executable versions) and processed nuclear data files to promote on-going research, to help ensure nuclear and radiological safety, and to advance nuclear technology. The role of such information analysis centers is critical for supporting and sustaining nuclear education and training programmes both domestically and internationally, as the majority of RSICC’s customers are students attending U.S. universities. RSICC also supports and promotes workshops and seminars in nuclear science and technology to further the use and/or development of computational tools and data. Additionally, RSICC operates a secure CLOUD computing system to provide access to sensitive export-controlled modeling and simulation (M&S) tools that support both domestic and international activities. This presentation will provide a general review of RSICC’s activities, services, and systems that support knowledge management and education and training in the nuclear field. (author

Radiation effects in metal-oxide-semiconductor capacitors

International Nuclear Information System (INIS)

Collins, J.L.

1987-01-01

The effects of various radiations on commercially made Al-SiO 2 -Si Capacitors (MOSCs) have been investigated. Intrinsic dielectric breakdown in MOSCs has been shown to be a two-stage process dominated by charge injection in a pre-breakdown stage; this is associated with localised high-field injection of carriers from the semiconductor substrate to interfacial and bulk charge traps which, it is proposed, leads to the formation of conducting channels through the dielectric with breakdown occurring as a result of the dissipation of the conduction band energy. A study of radiation-induced dielectric breakdown has revealed the possibility of anomalous hot-electron injection to an excess of bulk oxide traps in the ionization channel produced by very heavily ionizing radiation, which leads to intrinsic breakdown in high-field stressed devices. This is interpreted in terms of a modified model for radiation-induced dielectric breakdown based upon the primary dependence of breakdown on charge injection rather than high-field mechanisms. A detailed investigation of charge trapping and interface state generation due to various radiations has revealed evidence of neutron induced interface states, and the generation of positive oxide charge in devices due to all the radiations tested. The greater the linear energy transfer of the radiation, the greater the magnitude of charge trapped in the oxide and the number of interface states generated. This is interpreted in terms of Si-H and Si-OH bond-breaking at the Si-SiO 2 interface which is enhanced by charge carrier transfer to the interface and by anomalous charge injection to compensate for the excess of charge carriers created by the radiation. (author)

White Paper of the Society of Computed Body Tomography and Magnetic Resonance on Dual-Energy CT, Part 2: Radiation Dose and Iodine Sensitivity.

Science.gov (United States)

Foley, W Dennis; Shuman, William P; Siegel, Marilyn J; Sahani, Dushyant V; Boll, Daniel T; Bolus, David N; De Cecco, Carlo N; Kaza, Ravi K; Morgan, Desiree E; Schoepf, U Joseph; Vrtiska, Terri J; Yeh, Benjamin M; Berland, Lincoln L

This is the second of a series of 4 white papers that represent Expert Consensus Documents developed by the Society of Computed Body Tomography and Magnetic Resonance through its task force on dual-energy computed tomography. This paper, part 2, addresses radiation dose and iodine sensitivity in dual-energy computed tomography.

Quantitative analysis of polarization phenomena in CdTe radiation detectors

International Nuclear Information System (INIS)

Toyama, Hiroyuki; Higa, Akira; Yamazato, Masaaki; Maehama, Takehiro; Toguchi, Minoru; Ohno, Ryoichi

2006-01-01

Polarization phenomena in a Schottky-type CdTe radiation detector were studied. We evaluated the distribution of electric field in a biased CdTe detector by measuring the progressive change of Schottky barrier lowering with time. The parameters of deep acceptors such as detrapping time, concentration, and the depth of the energy level were quantitatively evaluated. In the case of applying the conventional model of charge accumulation, the obtained result shows that the CdTe bulk is never undepleted. We modified the charge accumulation model by taking account of the occupation state of the deep acceptor level. When a modified model is applied, the time that the depletion width in the bulk begins to diminish closely fits the time that the photopeak position begins to shift in radiation measurements. In this paper, we present a distribution of electric field during biasing and a simple method for the evaluation of the parameters of deep acceptors in CdTe bulk. (author)

Development of the computer code to monitor gamma radiation in the nuclear facility environment

International Nuclear Information System (INIS)

Akhmad, Y. R.; Pudjiyanto, M.S.

1998-01-01

Computer codes for gamma radiation monitoring in the vicinity of nuclear facility which have been developed could be introduced to the commercial potable gamma analyzer. The crucial stage of the first year activity was succeeded ; that is the codes have been tested to transfer data file (pulse high distribution) from Micro NOMAD gamma spectrometer (ORTEC product) and the convert them into dosimetry and physics quantities. Those computer codes are called as GABATAN (Gamma Analyzer of Batan) and NAGABAT (Natural Gamma Analyzer of Batan). GABATAN code can isable to used at various nuclear facilities for analyzing gamma field up to 9 MeV, while NAGABAT could be used for analyzing the contribution of natural gamma rays to the exposure rate in the certain location

Gamma-ray attenuation to measure water contents and/or bulk densities of porous materials

International Nuclear Information System (INIS)

Ferraz, E.S.B.

1983-01-01

Attenuation of gamma radiation during transmission through soil and porous materials has been used for approximately three decades as a method for determining volumetric water content, theta, and bulk density, rho. This method is particularly suited for laboratory determinations of theta and rho in soil columns but it also has been used with success under field conditions. Measurements of attentuation of a collimated beam of monoernergetic gamma-rays has been used successfully by many investigators to provide rapid, non-destructive determinations for small volumes of soil. For stable soils, i.e. soils which do not swell upon wetting or shrink upon drying, rho may be assumed to remain constant during water flow through the soil, and thus changes in intensity or transmitted radiation may be attributed to changes in water content, theta. However, for unstable soils, the dry bulk density is subject to change with time during water flow through the soil and cannot be assumed to be a constant. Several investigators have utilized either a single beam of dual-energy gamma photons or two separate monoenergetic photon beams with greatly different energies to simultaneously determine theta and rho in these soils. A general review of gamma-ray attenuation methods for determining theta and rho in laboratory soil cores and in field soil profiles is reported in this paper. Theoretical equations for transmission and attenuation of gamma radiation in soils are presented for both single and double beams of gamma photons. Sensitivity, precision, accuracy, and experimental errors for the method are evaluated and discussed with respect to the theory. (author)

Surprising radiation detectors

CERN Document Server

Fleischer, Robert

2003-01-01

Radiation doses received by the human body can be measured indirectly and retrospectively by counting the tracks left by particles in ordinary objects like pair of spectacles, glassware, compact disks...This method has been successfully applied to determine neutron radiation doses received 50 years ago on the Hiroshima site. Neutrons themselves do not leave tracks in bulk matter but glass contains atoms of uranium that may fission when hurt by a neutron, the recoil of the fission fragments generates a track that is detectable. The most difficult is to find adequate glass items and to evaluate the radiation shield they benefited at their initial place. The same method has been used to determine the radiation dose due to the pile-up of radon in houses. In that case the tracks left by alpha particles due to the radioactive decay of polonium-210 have been counted on the superficial layer of the window panes. Other materials like polycarbonate plastics have been used to determine the radiation dose due to heavy io...

Reduced radiation exposure to the mammary glands in thoracic computed tomography using organ-based tube-current modulation

International Nuclear Information System (INIS)

Munechika, Jiro; Ohgiya, Yoshimitsu; Gokan, Takehiko; Hashimoto, Toshi; Iwai, Tsugunori

2013-01-01

Organ-based tube-current modulation has been used to reduce radiation exposure to specific organs. However, there are no reports yet published on reducing radiation exposure in clinical cases. In this study, we assessed the reduction in radiation exposure to the mammary glands during thoracic computed tomography (CT) using X-CARE. In a phantom experiment, the use of X-CARE reduced radiation exposure at the midline of the precordial region by a maximum of 45.1%. In our corresponding clinical study, CT was performed using X-CARE in 15 patients, and without X-CARE in another 15. Compared to the non-X-CARE group, radiation exposure was reduced in the X-CARE group at the midline of the precordial region by 22.3% (P 0.05). X-CARE thus reduced radiation exposure at the midline of the precordial region and allowed us to obtain consistent CT values without increasing noise. However, this study revealed increases in radiation exposure at the lateral sides of the breasts. It is conceivable that patients' breasts were laterally displaced by gravity under the standard thoracic imaging conditions. Further studies that consider factors such as body size and adjustment of imaging conditions may be needed in the future. (author)

Abstracts of digital computer code packages assembled by the Radiation Shielding Information Center

International Nuclear Information System (INIS)

Carter, B.J.; Maskewitz, B.F.

1985-04-01

This publication, ORNL/RSIC-13, Volumes I to III Revised, has resulted from an internal audit of the first 168 packages of computing technology in the Computer Codes Collection (CCC) of the Radiation Shielding Information Center (RSIC). It replaces the earlier three documents published as single volumes between 1966 to 1972. A significant number of the early code packages were considered to be obsolete and were removed from the collection in the audit process and the CCC numbers were not reassigned. Others not currently being used by the nuclear R and D community were retained in the collection to preserve technology not replaced by newer methods, or were considered of potential value for reference purposes. Much of the early technology, however, has improved through developer/RSIC/user interaction and continues at the forefront of the advancing state-of-the-art

Abstracts of digital computer code packages assembled by the Radiation Shielding Information Center

Energy Technology Data Exchange (ETDEWEB)

Carter, B.J.; Maskewitz, B.F.

1985-04-01

This publication, ORNL/RSIC-13, Volumes I to III Revised, has resulted from an internal audit of the first 168 packages of computing technology in the Computer Codes Collection (CCC) of the Radiation Shielding Information Center (RSIC). It replaces the earlier three documents published as single volumes between 1966 to 1972. A significant number of the early code packages were considered to be obsolete and were removed from the collection in the audit process and the CCC numbers were not reassigned. Others not currently being used by the nuclear R and D community were retained in the collection to preserve technology not replaced by newer methods, or were considered of potential value for reference purposes. Much of the early technology, however, has improved through developer/RSIC/user interaction and continues at the forefront of the advancing state-of-the-art.

Development and design of a computer-assisted information management system for radiation safety management at the University of Washington

International Nuclear Information System (INIS)

Riches, C.G.; Riordan, F.J.; Robb, D.; Grieb, C.; Pence, G.; O'Brien, M.J.

1984-01-01

The Radiation Safety Office (RSO) at the University of Washington (UW) found that it needed a computerized information system to help manage the campus radiation safety program and to help provide the records necessary to show compliance with regulations and license requirements. The John L. Locke Computer Center at the UW had just developed the GLAMOR system to aid information entry and query for their computer when the RSO turned to them for assistance. The module that was developed provided a mechanism for controlling and monitoring radioactive materials on campus. This became one part of a multi-faceted system that registers users, employees, sealed sources and radiation-producing machines. The system is designed to be interactive, for immediate information recall, and powerful enough to provide routine and special reports on compliance status. The RSO information system is designed to be flexible and can easily incorporate additional features. Some future features include an interactive SNM control program, an interface to the information system currently being developed for the occupational safety and health program and an interface to the database provided by the commercial film badge service used by the University. Development of this program lead the RSO to appreciate the usefulness of having health physics professionals on the staff who were also knowledgeable about computers and who could develop programs and reports necessary to their activities

Dynamic behavior of microscale particles controlled by standing bulk acoustic waves

Energy Technology Data Exchange (ETDEWEB)

Greenhall, J.; Raeymaekers, B., E-mail: bart.raeymaekers@utah.edu [Department of Mechanical Engineering, University of Utah, Salt Lake City, Utah 84112 (United States); Guevara Vasquez, F. [Department of Mathematics, University of Utah, Salt Lake City, Utah 84112 (United States)

2014-10-06

We analyze the dynamic behavior of a spherical microparticle submerged in a fluid medium, driven to the node of a standing bulk acoustic wave created by two opposing transducers. We derive the dynamics of the fluid-particle system taking into account the acoustic radiation force and the time-dependent and time-independent drag force acting on the particle. Using this dynamic model, we characterize the transient and steady-state behavior of the fluid-particle system as a function of the particle and fluid properties and the transducer operating parameters. The results show that the settling time and percent overshoot of the particle trajectory are dependent on the ratio of the acoustic radiation force and time-independent damping force. In addition, we show that the particle oscillates around the node of the standing wave with an amplitude that depends on the ratio of the time-dependent drag forces and the particle inertia.

Handling of bulk solids theory and practice

CERN Document Server

Shamlou, P A

1990-01-01

Handling of Bulk Solids provides a comprehensive discussion of the field of solids flow and handling in the process industries. Presentation of the subject follows classical lines of separate discussions for each topic, so each chapter is self-contained and can be read on its own. Topics discussed include bulk solids flow and handling properties; pressure profiles in bulk solids storage vessels; the design of storage silos for reliable discharge of bulk materials; gravity flow of particulate materials from storage vessels; pneumatic transportation of bulk solids; and the hazards of solid-mater

Automatic computation of radiative corrections

International Nuclear Information System (INIS)

Fujimoto, J.; Ishikawa, T.; Shimizu, Y.; Kato, K.; Nakazawa, N.; Kaneko, T.

1997-01-01

Automated systems are reviewed focusing on their general structure and requirement specific to the calculation of radiative corrections. Detailed description of the system and its performance is presented taking GRACE as a concrete example. (author)

Development of a space radiation Monte Carlo computer simulation based on the FLUKA and ROOT codes

CERN Document Server

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...

Ferromagnetic bulk glassy alloys

International Nuclear Information System (INIS)

Inoue, Akihisa; Makino, Akihiro; Mizushima, Takao

2000-01-01

This paper deals with the review on the formation, thermal stability and magnetic properties of the Fe-based bulk glassy alloys in as-cast bulk and melt-spun ribbon forms. A large supercooled liquid region over 50 K before crystallization was obtained in Fe-(Al, Ga)-(P, C, B, Si), Fe-(Cr, Mo, Nb)-(Al, Ga)-(P, C, B) and (Fe, Co, Ni)-Zr-M-B (M=Ti, Hf, V, Nb, Ta, Cr, Mo and W) systems and bulk glassy alloys were produced in a thickness range below 2 mm for the Fe-(Al, Ga)-(P, C, B, Si) system and 6 mm for the Fe-Co-(Zr, Nb, Ta)-(Mo, W)-B system by copper-mold casting. The ring-shaped glassy Fe-(Al, Ga)-(P, C, B, Si) alloys exhibit much better soft magnetic properties as compared with the ring-shaped alloy made from the melt-spun ribbon because of the formation of the unique domain structure. The good combination of high glass-forming ability and good soft magnetic properties indicates the possibility of future development as a new bulk glassy magnetic material

Calculation of the secondary gamma radiation by the Monte Carlo method at displaced sampling from distributed sources

International Nuclear Information System (INIS)

Petrov, Eh.E.; Fadeev, I.A.

1979-01-01

A possibility to use displaced sampling from a bulk gamma source in calculating the secondary gamma fields by the Monte Carlo method is discussed. The algorithm proposed is based on the concept of conjugate functions alongside the dispersion minimization technique. For the sake of simplicity a plane source is considered. The algorithm has been put into practice on the M-220 computer. The differential gamma current and flux spectra in 21cm-thick lead have been calculated. The source of secondary gamma-quanta was assumed to be a distributed, constant and isotropic one emitting 4 MeV gamma quanta with the rate of 10 9 quanta/cm 3 xs. The calculations have demonstrated that the last 7 cm of lead are responsible for the whole gamma spectral pattern. The spectra practically coincide with the ones calculated by the ROZ computer code. Thus the algorithm proposed can be offectively used in the calculations of secondary gamma radiation transport and reduces the computation time by 2-4 times

Shear and bulk viscosity of high-temperature gluon plasma

Science.gov (United States)

Zhang, Le; Hou, De-Fu

2018-05-01

We calculate the shear viscosity (η) and bulk viscosity (ζ) to entropy density (s) ratios η/s and ζ/s of a gluon plasma system in kinetic theory, including both the elastic {gg}≤ftrightarrow {gg} forward scattering and the inelastic soft gluon bremsstrahlung {gg}≤ftrightarrow {ggg} processes. Due to the suppressed contribution to η and ζ in the {gg}≤ftrightarrow {gg} forward scattering and the effective g≤ftrightarrow {gg} gluon splitting, Arnold, Moore and Yaffe (AMY) and Arnold, Dogan and Moore (ADM) have got the leading order computations for η and ζ in high-temperature QCD matter. In this paper, we calculate the correction to η and ζ in the soft gluon bremsstrahlung {gg}≤ftrightarrow {ggg} process with an analytic method. We find that the contribution of the collision term from the {gg}≤ftrightarrow {ggg} soft gluon bremsstrahlung process is just a small perturbation to the {gg}≤ftrightarrow {gg} scattering process and that the correction is at ∼5% level. Then, we obtain the bulk viscosity of the gluon plasma for the number-changing process. Furthermore, our leading-order result for bulk viscosity is the formula \\zeta \\propto \\tfrac{{α }s2{T}3}{ln}{α }s-1} in high-temperature gluon plasma. Supported by Ministry of Science and Technology of China (MSTC) under the “973” Project (2015CB856904(4)) and National Natural Science Foundation of China (11735007, 11521064)

About using of the high-speed modular computing structures in the systems of radiation express analysis

Energy Technology Data Exchange (ETDEWEB)

Ermalitski, F A

1996-12-31

In accordance with parallel processing conception the original method for definition of the stream intensity of Poisson group is proposed, which is able to use for radiation express analysis. Within the framework of this method the parallel measure-calculating procedure is created and the high-speed modular computing system is designed for its implementation. 5 refs.

Preliminary radiation shielding design for BOOMERANG

International Nuclear Information System (INIS)

Donahue, Richard J.

2002-01-01

Preliminary radiation shielding specifications are presented here for the 3 GeV BOOMERANG Australian synchrotron light source project. At this time the bulk shield walls for the storage ring and injection system (100 MeV Linac and 3 GeV Booster) are considered for siting purposes

Bulk Comptonization of the Cosmic Microwave Background by Extragalactic Jets as a Probe of their Matter Content

Science.gov (United States)

Georganopoulos, Markos; Kazanas, Demosthenes; Perlman, Eric; Stecker, Floyd W.

2004-01-01

We propose a method for estimating the composition, i.e. the relative amounts of leptons and protons, of extragalactic jets which exhibit Chandra - detected knots in their kpc scale jets. The method relies on measuring, or setting upper limits on, the component of the Cosmic Microwave Background (CMB) radiation that is bulk-Comptonized by the cold electrons in the relativistically flowing jet. These measurements, along with modeling of the broadband knot emission that constrain the bulk Lorentz factor GAMMA of the jets, can yield estimates of the jet power carried by protons and leptons. We provide an explicit calculation of the spectrum of the bulk-Comptonized (BC) CMB component and apply these results to PKS 0637 - 752 and 3C 273, two superluminal quasars with Chandra - detected large scale jets. What makes these sources particularly suited for such a procedure is the absence of significant non-thermal jet emission in the 'bridge', the region between the core and the first bright jet knot, which guarantees that most of the electrons are cold there, leaving the BC scattered CMB radiation as the only significant source of photons in this region. At lambda = 3.6 - 8.0 microns, the most likely band to observe the BC scattered CMB emission, the Spitzer angular resolution (approximately 1" - 3") is considerably smaller than the the 'bridges' of these jets (approximately 10"), making it possible to both measure and resolve this emission.

Generating Efficient Femtosecond Mid-infrared Pulse by Single Near-infrared Pump Wavelength in Bulk Nonlinear Crystal Without Phase-matching

DEFF Research Database (Denmark)

Zhou, Binbin; Guo, Hairun; Bache, Morten

2014-01-01

We experimentally demonstrate efficient mid-infrared pulse generation by dispersive wave radiation in bulk lithium niobate crystal. Femtosecond mid-IR pulses centering from 2.8-2.92 μm are generated using the single pump wavelengths from 1.25-1.45 μm. © 2014 Optical Society of America...

On binding energy of trions in bulk materials

Science.gov (United States)

Filikhin, Igor; Kezerashvili, Roman Ya.; Vlahovic, Branislav

2018-03-01

We study the negatively T- and positively T+ charged trions in bulk materials in the effective mass approximation within the framework of a potential model. The binding energies of trions in various semiconductors are calculated by employing Faddeev equation in configuration space. Results of calculations of the binding energies for T- are consistent with previous computational studies and are in reasonable agreement with experimental measurements, while the T+ is unbound for all considered cases. The mechanism of formation of the binding energy of trions is analyzed by comparing contributions of a mass-polarization term related to kinetic energy operators and a term related to the Coulomb repulsion of identical particles.

Effect of radiation dose reduction and iterative reconstruction on computer-aided detection of pulmonary nodules : Intra-individual comparison

NARCIS (Netherlands)

Den Harder, Annemarie M.; Willemink, Martin J.; Van Hamersvelt, Robbert W.; Vonken, Evert-Jan P A; Milles, Julien; Schilham, Arnold M R; Lammers, Jan Willem; De Jong, Pim A.; Leiner, Tim; Budde, Ricardo P J

2016-01-01

Objective To evaluate the effect of radiation dose reduction and iterative reconstruction (IR) on the performance of computer-aided detection (CAD) for pulmonary nodules. Methods In this prospective study twenty-five patients were included who were scanned for pulmonary nodule follow-up. Image

Process controls for radiation hardened aluminum gate bulk silicon CMOS

International Nuclear Information System (INIS)

Gregory, B.L.

1975-01-01

Optimized dry oxides have recently yielded notable improvements in CMOS radiation-hardness. By following the proper procedures and recipes, it is now possible to produce devices which will function satisfactorily after exposure to a total ionizing dose in excess of 10 6 RADS (Si). This paper is concerned with the controls required on processing parameters once the optimized process is defined. In this process, the pre-irradiation electrical parameters must be closely controlled to insure that devices will function after irradiation. In particular, the specifications on n- and p-channel threshold voltages require tight control of fixed oxide charge, surface-state density, oxide thickness, and substrate and p-well surface concentrations. In order to achieve the above level of radiation hardness, certain processing procedures and parameters must also be closely controlled. Higher levels of cleanliness are required in the hardened process than are commonly required for commercial CMOS since, for hardened dry oxides, no impurity gettering can be employed during or after oxidation. Without such gettering, an unclean oxide is unacceptable due to bias-temperature instability. Correct pre-oxidation cleaning, residual surface damage removal, proper oxidation and annealing temperatures and times, and the correct metal sintering cycle are all important in determining device hardness. In a reproducible, hardened process, each of these processing steps must be closely controlled. (U.S.)

Segmentation of Synchrotron Radiation micro-Computed Tomography Images using Energy Minimization via Graph Cuts

International Nuclear Information System (INIS)

Meneses, Anderson A.M.; Giusti, Alessandro; Almeida, André P. de; Nogueira, Liebert; Braz, Delson; Almeida, Carlos E. de; Barroso, Regina C.

2012-01-01

The research on applications of segmentation algorithms to Synchrotron Radiation X-Ray micro-Computed Tomography (SR-μCT) is an open problem, due to the interesting and well-known characteristics of SR images, such as the phase contrast effect. The Energy Minimization via Graph Cuts (EMvGC) algorithm represents state-of-art segmentation algorithm, presenting an enormous potential of application in SR-μCT imaging. We describe the application of the algorithm EMvGC with swap move for the segmentation of bone images acquired at the ELETTRA Laboratory (Trieste, Italy). - Highlights: ► Microstructures of Wistar rats' ribs are investigated with Synchrotron Radiation μCT imaging. ► The present work is part of a research on the effects of radiotherapy on the thoracic region. ► Application of the Energy Minimization via Graph Cuts algorithm for segmentation is described.

QALMA: A computational toolkit for the analysis of quality protocols for medical linear accelerators in radiation therapy

Science.gov (United States)

Rahman, Md Mushfiqur; Lei, Yu; Kalantzis, Georgios

2018-01-01

Quality Assurance (QA) for medical linear accelerator (linac) is one of the primary concerns in external beam radiation Therapy. Continued advancements in clinical accelerators and computer control technology make the QA procedures more complex and time consuming which often, adequate software accompanied with specific phantoms is required. To ameliorate that matter, we introduce QALMA (Quality Assurance for Linac with MATLAB), a MALAB toolkit which aims to simplify the quantitative analysis of QA for linac which includes Star-Shot analysis, Picket Fence test, Winston-Lutz test, Multileaf Collimator (MLC) log file analysis and verification of light & radiation field coincidence test.

The prospects for very high-power electron accelerators for processing bulk materials

International Nuclear Information System (INIS)

Cleland, M.R.; Thompson, C.C.; Malone, H.F.

1977-01-01

The recent growth in the industrial usage of ionizing radiation has been stimulated by the development of reliable, high-power, electron beam generators which operate in the beam power range of 10 to 100 kilowatts. This high output has reduced the costs of radiation processes to about 0.001 dollars per megarad-pound of product material. At this rate electron beam treatment is now less expensive than conventional methods for curing plastic and rubber products and sterilizing medical disposables. Future applications of electron beam radiation to bulk chemicals and waste materials will require even larger generators operating in the power range of 100 to 1000 kilowatts to handle greater material thruputs. Unit processing costs must be further reduced because of the lower intrinsic values of these materials. Fortunately, lower unit costs will follow the development of more powerful equipment because most of the cost factors do not increase in proportion to the output power. This is demonstrated by analyzing the downward trends in radiation processing costs as the machine voltage and the beam current are increased. The Dynamitron accelerator technology is reviewed to show that this could be one method of achieving the projected power levels. Several large-scale radiation processes are discussed to show that applications can be found for electron beam systems operating in the projected range. (author)

Radiation Hardening of Silicon Detectors

CERN Multimedia

Leroy, C; Glaser, M

2002-01-01

%RD48 %title\\\\ \\\\Silicon detectors will be widely used in experiments at the CERN Large Hadron Collider where high radiation levels will cause significant bulk damage. In addition to increased leakage current and charge collection losses worsening the signal to noise, the induced radiation damage changes the effective doping concentration and represents the limiting factor to long term operation of silicon detectors. The objectives are to develop radiation hard silicon detectors that can operate beyond the limits of the present devices and that ensure guaranteed operation for the whole lifetime of the LHC experimental programme. Radiation induced defect modelling and experimental results show that the silicon radiation hardness depends on the atomic impurities present in the initial monocrystalline material.\\\\ \\\\ Float zone (FZ) silicon materials with addition of oxygen, carbon, nitrogen, germanium and tin were produced as well as epitaxial silicon materials with epilayers up to 200 $\\mu$m thickness. Their im...

Computational hybrid anthropometric paediatric phantom library for internal radiation dosimetry

Science.gov (United States)

Xie, Tianwu; Kuster, Niels; Zaidi, Habib

2017-04-01

Hybrid computational phantoms combine voxel-based and simplified equation-based modelling approaches to provide unique advantages and more realism for the construction of anthropomorphic models. In this work, a methodology and C++ code are developed to generate hybrid computational phantoms covering statistical distributions of body morphometry in the paediatric population. The paediatric phantoms of the Virtual Population Series (IT’IS Foundation, Switzerland) were modified to match target anthropometric parameters, including body mass, body length, standing height and sitting height/stature ratio, determined from reference databases of the National Centre for Health Statistics and the National Health and Nutrition Examination Survey. The phantoms were selected as representative anchor phantoms for the newborn, 1, 2, 5, 10 and 15 years-old children, and were subsequently remodelled to create 1100 female and male phantoms with 10th, 25th, 50th, 75th and 90th body morphometries. Evaluation was performed qualitatively using 3D visualization and quantitatively by analysing internal organ masses. Overall, the newly generated phantoms appear very reasonable and representative of the main characteristics of the paediatric population at various ages and for different genders, body sizes and sitting stature ratios. The mass of internal organs increases with height and body mass. The comparison of organ masses of the heart, kidney, liver, lung and spleen with published autopsy and ICRP reference data for children demonstrated that they follow the same trend when correlated with age. The constructed hybrid computational phantom library opens up the prospect of comprehensive radiation dosimetry calculations and risk assessment for the paediatric population of different age groups and diverse anthropometric parameters.

Estimating the effective radiation dose imparted to patients by intraoperative cone-beam computed tomography in thoracolumbar spinal surgery.

Science.gov (United States)

Lange, Jeffrey; Karellas, Andrew; Street, John; Eck, Jason C; Lapinsky, Anthony; Connolly, Patrick J; Dipaola, Christian P

2013-03-01

Observational. To estimate the radiation dose imparted to patients during typical thoracolumbar spinal surgical scenarios. Minimally invasive techniques continue to become more common in spine surgery. Computer-assisted navigation systems coupled with intraoperative cone-beam computed tomography (CT) represent one such method used to aid in instrumented spinal procedures. Some studies indicate that cone-beam CT technology delivers a relatively low dose of radiation to patients compared with other x-ray-based imaging modalities. The goal of this study was to estimate the radiation exposure to the patient imparted during typical posterior thoracolumbar instrumented spinal procedures, using intraoperative cone-beam CT and to place these values in the context of standard CT doses. Cone-beam CT scans were obtained using Medtronic O-arm (Medtronic, Minneapolis, MN). Thermoluminescence dosimeters were placed in a linear array on a foam-plastic thoracolumbar spine model centered above the radiation source for O-arm presets of lumbar scans for small or large patients. In-air dosimeter measurements were converted to skin surface measurements, using published conversion factors. Dose-length product was calculated from these values. Effective dose was estimated using published effective dose to dose-length product conversion factors. Calculated dosages for many full-length procedures using the small-patient setting fell within the range of published effective doses of abdominal CT scans (1-31 mSv). Calculated dosages for many full-length procedures using the large-patient setting fell within the range of published effective doses of abdominal CT scans when the number of scans did not exceed 3. We have demonstrated that single cone-beam CT scans and most full-length posterior instrumented spinal procedures using O-arm in standard mode would likely impart a radiation dose within the range of those imparted by a single standard CT scan of the abdomen. Radiation dose increases

Estimation of radiation exposure from lung cancer screening program with low-dose computed tomography

Energy Technology Data Exchange (ETDEWEB)

Kim, Su Yeon; Jun, Jae Kwan [Graduate School of Cancer Science and Policy, National Cancer Center, Seoul (Korea, Republic of)

2016-12-15

The National Lung Screening Trial (NLST) demonstrated that screening with Low-dose Computed Tomography (LDCT) screening reduced lung cancer mortality in a high-risk population. Recently, the United States Preventive Services Task Force (USPSTF) gave a B recommendation for annual LDCT screening for individuals at high-risk. With the promising results, Korea developed lung cancer screening guideline and is planning a pilot study for implementation of national lung cancer screening. With widespread adoption of lung cancer screening with LDCT, there are concerns about harms of screening, including high false-positive rates and radiation exposure. Over the 3 rounds of screening in the NLST, 96.4% of positive results were false-positives. Although the initial screening is performed at low dose, subsequent diagnostic examinations following positive results additively contribute to patient's lifetime exposure. As with implementing a large-scale screening program, there is a lack of established risk assessment about the effect of radiation exposure from long-term screening program. Thus, the purpose of this study was to estimate cumulative radiation exposure of annual LDCT lung cancer screening program over 20-year period.

Influence of Ice Particle Surface Roughening on the Global Cloud Radiative Effect

Science.gov (United States)

Yi, Bingqi; Yang, Ping; Baum, Bryan A.; LEcuyer, Tristan; Oreopoulos, Lazaros; Mlawer, Eli J.; Heymsfield, Andrew J.; Liou, Kuo-Nan

2013-01-01

Ice clouds influence the climate system by changing the radiation budget and large-scale circulation. Therefore, climate models need to have an accurate representation of ice clouds and their radiative effects. In this paper, new broadband parameterizations for ice cloud bulk scattering properties are developed for severely roughened ice particles. The parameterizations are based on a general habit mixture that includes nine habits (droxtals, hollow/solid columns, plates, solid/hollow bullet rosettes, aggregate of solid columns, and small/large aggregates of plates). The scattering properties for these individual habits incorporate recent advances in light-scattering computations. The influence of ice particle surface roughness on the ice cloud radiative effect is determined through simulations with the Fu-Liou and the GCM version of the Rapid Radiative Transfer Model (RRTMG) codes and the National Center for Atmospheric Research Community Atmosphere Model (CAM, version 5.1). The differences in shortwave (SW) and longwave (LW) radiative effect at both the top of the atmosphere and the surface are determined for smooth and severely roughened ice particles. While the influence of particle roughening on the single-scattering properties is negligible in the LW, the results indicate that ice crystal roughness can change the SW forcing locally by more than 10 W m(exp -2) over a range of effective diameters. The global-averaged SW cloud radiative effect due to ice particle surface roughness is estimated to be roughly 1-2 W m(exp -2). The CAM results indicate that ice particle roughening can result in a large regional SW radiative effect and a small but nonnegligible increase in the global LW cloud radiative effect.

Crystallization in Zr41.2Ti13.8Cu12.5Ni10Be22.5 bulk metallic glass under pressure

DEFF Research Database (Denmark)

Jiang, Jianzhong; Zhou, T.J.; Rasmussen, Helge Kildahl

2000-01-01

The effect of pressure on the crystallization behavior of the bulk metallic glass-forming Zr41.2Ti13.8Cu12.5Ni10Be22.5 alloy with a wide supercooled liquid region has been investigated by in situ high-pressure and high-temperature x-ray powder diffraction measurements using synchrotron radiation......)], reporting a decrease of the crystallization temperature under pressure in a pressure range of 0-6 GPa for the bulk glass Zr41Ti14Cu12.5Ni9Be22.5C1 alloy. Compressibility with a volume reduction of approximately 22% at room temperature does not induce crystallization in the Zr41.2Ti13.8Cu12.5Ni10Be22.5 bulk...... glass alloy. This indicates that the densification effect induced by pressure in the pressure range investigated plays a minor role in the crystallization behavior of this bulk glass alloy. The different crystallization behavior of the carbon-free and the carbon-containing glassy alloys has been...

A study of preparation techniques and properties of bulk nanocomposites based on aqueous albumin dispersion

Science.gov (United States)

Gerasimenko, A. Yu.; Dedkova, A. A.; Ichkitidze, L. P.; Podgaetskii, V. M.; Selishchev, S. V.

2013-08-01

Bulk nanocomposites prepared from an aqueous albumin dispersion with carbon nanotubes by removing the liquid component from the dispersion have been investigated. The composites were obtained by thermostating and exposure to LED and IR diode laser radiation. The nanocomposites obtained under laser irradiation retain their shape and properties for several years, in contrast to the composites fabricated in different ways (which decompose into small fragments immediately after preparation). The low density of the composites under study (˜1200 kg/m3), which is close to the density of water, is due to their high porosity. The hardness of stable nanocomposites (˜300 MPa) was found to be at the same level as the hardness of polymethylmethacrylate, aluminum, and iron and close to the hardness of human bone tissue. The cluster quasiordering of the inner structure of nanocomposites revealed by atomic force microscopy indicates the possibility of forming a bulk nanotube framework in them, which can be caused by the effect of the electric field of laser radiation and ensure their stability and hardness. The presence of a framework in nanocomposites provides conditions for self-assembly of biological tissues and makes it possible to apply laser-prepared nanocomposites as a component of surgical implants.

Coupling brane fields to bulk supergravity

Energy Technology Data Exchange (ETDEWEB)

Parameswaran, Susha L. [Uppsala Univ. (Sweden). Theoretical Physics; Schmidt, Jonas [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany)

2010-12-15

In this note we present a simple, general prescription for coupling brane localized fields to bulk supergravity. We illustrate the procedure by considering 6D N=2 bulk supergravity on a 2D orbifold, with brane fields localized at the fixed points. The resulting action enjoys the full 6D N=2 symmetries in the bulk, and those of 4D N=1 supergravity at the brane positions. (orig.)

Radiation dose evaluation of dental cone beam computed tomography using an anthropomorphic adult head phantom

Science.gov (United States)

Wu, Jay; Shih, Cheng-Ting; Ho, Chang-hung; Liu, Yan-Lin; Chang, Yuan-Jen; Min Chao, Max; Hsu, Jui-Ting

2014-11-01

Dental cone beam computed tomography (CBCT) provides high-resolution tomographic images and has been gradually used in clinical practice. Thus, it is important to examine the amount of radiation dose resulting from dental CBCT examinations. In this study, we developed an in-house anthropomorphic adult head phantom to evaluate the level of effective dose. The anthropomorphic phantom was made of acrylic and filled with plaster to replace the bony tissue. The contour of the head was extracted from a set of adult computed tomography (CT) images. Different combinations of the scanning parameters of CBCT were applied. Thermoluminescent dosimeters (TLDs) were used to measure the absorbed doses at 19 locations in the head and neck regions. The effective doses measured using the proposed phantom at 65, 75, and 85 kVp in the D-mode were 72.23, 100.31, and 134.29 μSv, respectively. In the I-mode, the effective doses were 108.24, 190.99, and 246.48 μSv, respectively. The maximum percent error between the doses measured by the proposed phantom and the Rando phantom was l4.90%. Therefore, the proposed anthropomorphic adult head phantom is applicable for assessing the radiation dose resulting from clinical dental CBCT.

Survey of radiation protection, radiation transport, and shielding information needs of the nuclear power industry. Final report

International Nuclear Information System (INIS)

Maskewitz, B.F.; Trubey, D.K.; Roussin, R.W.; McGill, B.L.

1976-04-01

The Radiation Shielding Information Center (RSIC) is engaged in a program to seek out, organize, and disseminate information in the area of radiation transport, shielding, and radiation protection. This information consists of published literature, nuclear data, and computer codes and advanced analytical techniques required by ERDA, its contractors, and the nuclear power industry to improve radiation analysis and computing capability. Information generated in this effort becomes a part of the RSIC collection and/or data base. The purpose of this report on project 219-1 is to document the results of the survey of information and computer code needs of the nuclear power industry in the area of radiation analysis and protection

Survey of radiation protection, radiation transport, and shielding information needs of the nuclear power industry. Final report

Energy Technology Data Exchange (ETDEWEB)

Maskewitz, B.F.; Trubey, D.K.; Roussin, R.W.; McGill, B.L.

1976-04-01

The Radiation Shielding Information Center (RSIC) is engaged in a program to seek out, organize, and disseminate information in the area of radiation transport, shielding, and radiation protection. This information consists of published literature, nuclear data, and computer codes and advanced analytical techniques required by ERDA, its contractors, and the nuclear power industry to improve radiation analysis and computing capability. Information generated in this effort becomes a part of the RSIC collection and/or data base. The purpose of this report on project 219-1 is to document the results of the survey of information and computer code needs of the nuclear power industry in the area of radiation analysis and protection.

Modeling Radiative Heat Transfer and Turbulence-Radiation Interactions in Engines

Energy Technology Data Exchange (ETDEWEB)

Paul, Chandan [Pennsylvania State Univ., University Park, PA (United States); Sircar, Arpan [Pennsylvania State Univ., University Park, PA (United States); Ferreyro-Fernandez, Sebastian [Pennsylvania State Univ., University Park, PA (United States); Imren, Abdurrahman [Pennsylvania State Univ., University Park, PA (United States); Haworth, Daniel C [Pennsylvania State Univ., University Park, PA (United States); Roy, Somesh P [Marquette University (United States); Ge, Wenjun [University of California Merced (United States); Modest, Michael F [University of California Merced (United States)

2017-04-26

Detailed radiation modelling in piston engines has received relatively little attention to date. Recently, it is being revisited in light of current trends towards higher operating pressures and higher levels of exhaust-gas recirculation, both of which enhance molecular gas radiation. Advanced high-efficiency engines also are expected to function closer to the limits of stable operation, where even small perturbations to the energy balance can have a large influence on system behavior. Here several different spectral radiation property models and radiative transfer equation (RTE) solvers have been implemented in an OpenFOAM-based engine CFD code, and simulations have been performed for a full-load (peak pressure ~200 bar) heavy-duty diesel engine. Differences in computed temperature fields, NO and soot levels, and wall heat transfer rates are shown for different combinations of spectral models and RTE solvers. The relative importance of molecular gas radiation versus soot radiation is examined. And the influence of turbulence-radiation interactions is determined by comparing results obtained using local mean values of composition and temperature to compute radiative emission and absorption with those obtained using a particle-based transported probability density function method.

Bulk viscosity of spin-one color superconductors

Energy Technology Data Exchange (ETDEWEB)

Sa' d, Basil A.

2009-08-27

The bulk viscosity of several quark matter phases is calculated. It is found that the effect of color superconductivity is not trivial, it may suppress, or enhance the bulk viscosity depending on the critical temperature and the temperature at which the bulk viscosity is calculated. Also, is it found that the effect of neutrino-emitting Urca processes cannot be neglected in the consideration of the bulk viscosity of strange quark matter. The results for the bulk viscosity of strange quark matter are used to calculate the r-mode instability window of quark stars with several possible phases. It is shown that each possible phase has a different structure for the r-mode instability window. (orig.)

Bulk viscosity of spin-one color superconductors

International Nuclear Information System (INIS)

Sa'd, Basil A.

2009-01-01

The bulk viscosity of several quark matter phases is calculated. It is found that the effect of color superconductivity is not trivial, it may suppress, or enhance the bulk viscosity depending on the critical temperature and the temperature at which the bulk viscosity is calculated. Also, is it found that the effect of neutrino-emitting Urca processes cannot be neglected in the consideration of the bulk viscosity of strange quark matter. The results for the bulk viscosity of strange quark matter are used to calculate the r-mode instability window of quark stars with several possible phases. It is shown that each possible phase has a different structure for the r-mode instability window. (orig.)

Segmentation of Synchrotron Radiation micro-Computed Tomography Images using Energy Minimization via Graph Cuts

Energy Technology Data Exchange (ETDEWEB)

Meneses, Anderson A.M. [Federal University of Western Para (Brazil); Physics Institute, Rio de Janeiro State University (Brazil); Giusti, Alessandro [IDSIA (Dalle Molle Institute for Artificial Intelligence), University of Lugano (Switzerland); Almeida, Andre P. de, E-mail: apalmeid@gmail.com [Physics Institute, Rio de Janeiro State University (Brazil); Nuclear Engineering Program, Federal University of Rio de Janeiro (Brazil); Nogueira, Liebert; Braz, Delson [Nuclear Engineering Program, Federal University of Rio de Janeiro (Brazil); Almeida, Carlos E. de [Radiological Sciences Laboratory, Rio de Janeiro State University (Brazil); Barroso, Regina C. [Physics Institute, Rio de Janeiro State University (Brazil)

2012-07-15

The research on applications of segmentation algorithms to Synchrotron Radiation X-Ray micro-Computed Tomography (SR-{mu}CT) is an open problem, due to the interesting and well-known characteristics of SR images, such as the phase contrast effect. The Energy Minimization via Graph Cuts (EMvGC) algorithm represents state-of-art segmentation algorithm, presenting an enormous potential of application in SR-{mu}CT imaging. We describe the application of the algorithm EMvGC with swap move for the segmentation of bone images acquired at the ELETTRA Laboratory (Trieste, Italy). - Highlights: Black-Right-Pointing-Pointer Microstructures of Wistar rats' ribs are investigated with Synchrotron Radiation {mu}CT imaging. Black-Right-Pointing-Pointer The present work is part of a research on the effects of radiotherapy on the thoracic region. Black-Right-Pointing-Pointer Application of the Energy Minimization via Graph Cuts algorithm for segmentation is described.

Radiation dose management for pediatric cardiac computed tomography. A report from the Image Gently 'Have-A-Heart' campaign

International Nuclear Information System (INIS)

Rigsby, Cynthia K.; Sammet, Christina L.; McKenney, Sarah E.; Hill, Kevin D.; Chelliah, Anjali; Einstein, Andrew J.; Han, B.K.; Robinson, Joshua D.; Slesnick, Timothy C.; Frush, Donald P.

2018-01-01

Children with congenital or acquired heart disease can be exposed to relatively high lifetime cumulative doses of ionizing radiation from necessary medical imaging procedures including radiography, fluoroscopic procedures including diagnostic and interventional cardiac catheterizations, electrophysiology examinations, cardiac computed tomography (CT) studies, and nuclear cardiology examinations. Despite the clinical necessity of these imaging studies, the related ionizing radiation exposure could pose an increased lifetime attributable cancer risk. The Image Gently ''Have-A-Heart'' campaign is promoting the appropriate use of medical imaging studies in children with congenital or acquired heart disease while minimizing radiation exposure. The focus of this manuscript is to provide a comprehensive review of radiation dose management and CT performance in children with congenital or acquired heart disease. (orig.)

Radiation dose management for pediatric cardiac computed tomography. A report from the Image Gently 'Have-A-Heart' campaign

Energy Technology Data Exchange (ETDEWEB)

Rigsby, Cynthia K.; Sammet, Christina L. [Northwestern University Feinberg School of Medicine, Department of Medical Imaging 9, Ann and Robert H. Lurie Children' s Hospital of Chicago, Departments of Radiology and Pediatrics, Chicago, IL (United States); McKenney, Sarah E. [Children' s National Medical Center, Division of Diagnostic Imaging and Radiology, Washington, DC (United States); Hill, Kevin D. [Duke University Medical Center, Department of Pediatrics, Durham, NC (United States); Chelliah, Anjali [Columbia University Medical Center and New York-Presbyterian Hospital, Division of Pediatric Cardiology, New York, NY (United States); Einstein, Andrew J. [Columbia University Medical Center and New York-Presbyterian Hospital, Division of Cardiology, Departments of Medicine and Radiology, New York, NY (United States); Han, B.K. [Children' s Heart Clinic at The Children' s Hospitals and Clinics of Minnesota, Department of Pediatrics, Minneapolis, MN (United States); Robinson, Joshua D. [Northwestern University Feinberg School of Medicine, Division of Pediatric Cardiology, Ann and Robert H. Lurie Children' s Hospital of Chicago, Departments of Pediatrics and Radiology, Chicago, IL (United States); Slesnick, Timothy C. [Children' s Healthcare of Atlanta, Department of Pediatrics, Emory University School of Medicine, Atlanta, GA (United States); Frush, Donald P. [Duke University Medical Center, Department of Radiology, Durham, NC (United States)

2018-01-15

Children with congenital or acquired heart disease can be exposed to relatively high lifetime cumulative doses of ionizing radiation from necessary medical imaging procedures including radiography, fluoroscopic procedures including diagnostic and interventional cardiac catheterizations, electrophysiology examinations, cardiac computed tomography (CT) studies, and nuclear cardiology examinations. Despite the clinical necessity of these imaging studies, the related ionizing radiation exposure could pose an increased lifetime attributable cancer risk. The Image Gently ''Have-A-Heart'' campaign is promoting the appropriate use of medical imaging studies in children with congenital or acquired heart disease while minimizing radiation exposure. The focus of this manuscript is to provide a comprehensive review of radiation dose management and CT performance in children with congenital or acquired heart disease. (orig.)

A development of computer code for evaluating internal radiation dose through ingestion and inhalation pathways

International Nuclear Information System (INIS)

Lee, Jeong Ho; Lee, Chang Woo; Choi, Yong Ho; Chun, Ki Jung; Kim, Kook Chan; Kim, Sang Bok; Kim, Jin Kyu

1991-07-01

The computer codes were developed to evaluate internal radiation dose when radioactive isotopes released from nuclear facilities are taken through ingestion and inhalation pathways. Food chain models and relevant data base representing the agricultural and social environment of Korea are set up. An equilibrium model-KFOOD, which can deal with routine releases from a nuclear facility and a dynamic model-ECOREA, which is suitable for the description of acute radioactivity release following nuclear accident. (Author)

Surface, interface and bulk materials characterization using Indus synchrotron sources

International Nuclear Information System (INIS)

Phase, Deodatta M.

2014-01-01

Synchrotron radiation sources, providing intense, polarized and stable beams of ultra violet, soft and hard x-ray photons, are having great impact on physics, chemistry, biology, materials science and other areas research. In particular synchrotron radiation has revolutionized materials characterization techniques by enhancing its capabilities for investigating the structural, electronic and magnetic properties of solids. The availability of synchrotron sources and necessary instrumentation has led to considerable improvements in spectral resolution and intensities. As a result, application scope of different materials characterization techniques has tremendously increased particularly in the analysis of solid surfaces, interfaces and bulk materials. The Indian synchrotron storage ring, Indus-1 and Indus-2 are in operation at RRCAT, Indore. The UGC-DAE CSR with the help of university scientist had designed and developed an angle integrated photoelectron spectroscopy (AlPES) beam line on Indus-1 storage ring of 450 MeV and polarized light beam line for soft x-ray absorption spectroscopy (SXAS) on Indus-2 storage ring of 2.5 GeV. (author)

A study to assess the role of bulk density of process load in "6"0Co based food irradiation facility

International Nuclear Information System (INIS)

Sanyal, Bhaskar; Prakasan, V.; Chawla, S.P.; Ghosh, Sunil K.

2017-01-01

Radiation processing of foods and allied products is one of the important techniques to extend shelf-life. The success of this technology depends on the adequate dose delivery to the food products. The absorbed doses are functions of several irradiation parameters based on the design of the facility. The variable bulk density of the process load is of paramount importance in determining the dose uniformity. Bulk densities of the product in the range of 0.01 to 0.75 gm/cc were prepared and its influence on absorbed dose was studied in a "6"0Co based food package irradiator. The results established that the bulk densities of the process loads would considerably change the absorbed doses and dose uniformity. The data would be useful to the facility operators to take adequate decision in dosimetry procedures. (author)

A computer system for occupational radiation exposure information

International Nuclear Information System (INIS)

Hunt, H.W.

1984-01-01

A computerized occupational radiation exposure information system has been developed to maintain records for contractors at the U.S. Department of Energy's (DOE) Hanford Site. The system also allows indexing and retrieval of three million documents from microfilm, thus significantly reducing storage needs and costs. The users are linked by display terminals to the data base permitting them instant access to dosemetry and other radiation exposure information. Personnel dosemeter and bioassay results, radiation training, respirator fittings, skin contaminations and other radiation occurrence records are included in the data base. The system yields immediate analysis of radiological exposures for operating management and health physics personnel, thereby releasing personnel to use their time more effectively

Impact of intravenous contrast used in computed tomography on radiation dose to carotid arteries and thyroid in intensity-modulated radiation therapy planning for nasopharyngeal carcinoma

Energy Technology Data Exchange (ETDEWEB)

Lee, Victor Ho Fun, E-mail: vhflee@hku.hk; Ng, Sherry Chor Yi; Kwong, Dora Lai Wan; Lam, Ka On; Leung, To Wai

2017-07-01

The aim of this study was to investigate if intravenous contrast injection affected the radiation doses to carotid arteries and thyroid during intensity-modulated radiation therapy (IMRT) planning for nasopharyngeal carcinoma (NPC). Thirty consecutive patients with NPC underwent plain computed tomography (CT) followed by repeated scanning after contrast injection. Carotid arteries (common, external, internal), thyroid, target volumes, and other organs-at-risk (OARs), as well as IMRT planning, were based on contrast-enhanced CT (CE-CT) images. All these structures and the IMRT plans were then copied and transferred to the non–contrast-enhanced CT (NCE-CT) images, and dose calculation without optimization was performed again. The radiation doses to the carotid arteries and the thyroid based on CE-CT and NCE-CT were then compared. Based on CE-CT, no statistical differences, despite minute numeric decreases, were noted in all dosimetric parameters (minimum, maximum, mean, median, D05, and D01) of the target volumes, the OARs, the carotid arteries, and the thyroid compared with NCE-CT. Our results suggested that compared with NCE-CT planning, CE-CT scanning should be performed during IMRT for better target and OAR delineation, without discernible change in radiation doses.

Computing in an academic radiation therapy department

International Nuclear Information System (INIS)

Gottlieb, C.F.; Houdek, P.V.; Fayos, J.V.

1985-01-01

The authors conceptualized the different computer functions in radiotherapy as follows: 1) treatment planning and dosimetry, 2) data and word processing, 3) radiotherapy information system (data bank), 4) statistical analysis, 5) data acquisition and equipment control, 6) telecommunication, and 7) financial management. They successfully implemented the concept of distributed computing using multiple mini and personal computers. The authors' computer practice supports data and word processing, graphics, communication, automated data acquisition and control, and portable computing. The computers are linked together into a local computer network which permits sharing of information, peripherals, and unique programs among our systems, while preserving the individual function and identity of each machine. Furthermore, the architecture of our network allows direct access to any other computer network providing them with inexpensive use of the most modern and sophisticated software and hardware resources

Radiation protection in hospital radiopharmacy

International Nuclear Information System (INIS)

Kini, K.S.; Gaur, P.K.

1997-01-01

Short-lived radiopharmaceuticals, such as 99m Tc labelled compounds, are prepared in the in-house pharmacy of the hospital. In addition, preparation of smaller doses for administration from the bulk material of the finished product received from the manufacturers, also involves considerable work for the radiopharmacist in the hospital. Hence they should be well informed about the radiation hazards and should be aware of the protective measures to be taken while handling radioactive materials for keeping the radiation levels in the laboratory and their personnel doses well within the specified limits. 3 refs., 5 tabs

Ecological effects of ionizing radiation on population and ecosystem: a computational model ecosystem study

International Nuclear Information System (INIS)

Doi, Masahiro; Fuma, Shoichi; Ishii, Nobuyuki; Sakashita, Tetsuya; Miyamoto, Kiriko; Takeda, Hiroshi; Kawabata, Zenichiro

2003-01-01

Ecosystem is a self-sustaining system of complexity, and their responses to the impacts are synergistic and subjected to the demographic stochasticity of the species, environmental stochasticity and randomness. Environmental fate and effects of radiation has ranged from observable DNA damage of the cell to the fare on tissues, individual, population, community and ecosystems. The quantitative, systematic individual-based model, SIM-COSM was developed to simulate impacts of radiation exposure and other toxicants on an aquatic microbial ecosystem (microcosm). The microcosm consists of heterotroph ciliate protozoa (Tetrahymena thermophila B) as a consumer, autotroph flagellate algae (Euglena gracilis Z) as a producer and saprotroph bacteria (Escherichia coli DH5) as a decomposer. The symbiosis among microbes is self-organized by realizing material cycle and sustained for more than 2 years after inoculation. The system can not afford to lose any one of the microbes to maintain its sustainability. Experimental ecotoxicological tests for (a) gamma radiation, (b) Manganese ions and (c) Gadolinium are summarized. Population dynamics of microbes in Microcosm and its computer simulations by SIM-COSM are shown together in a figure. Population dynamics in Microcosm and SIM-COSM exposed to 500 Gy of gamma-radiation at 50 days after inoculation are shown also in a figure. To take the effects on the interactions between species and environment into account, one option is to put the ecotoxicity tests as experimental micro ecosystem study and theoretical model ecosystem analysis. (M. Suetake)

Correlation of radiation dose and heart rate in dual-source computed tomography coronary angiography.

Science.gov (United States)

Laspas, Fotios; Tsantioti, Dimitra; Roussakis, Arkadios; Kritikos, Nikolaos; Efthimiadou, Roxani; Kehagias, Dimitrios; Andreou, John

2011-04-01

Computed tomography coronary angiography (CTCA) has been widely used since the introduction of 64-slice scanners and dual-source CT technology, but the relatively high radiation dose remains a major concern. To evaluate the relationship between radiation exposure and heart rate (HR), in dual-source CTCA. Data from 218 CTCA examinations, performed with a dual-source 64-slices scanner, were statistically evaluated. Effective radiation dose, expressed in mSv, was calculated as the product of the dose-length product (DLP) times a conversion coefficient for the chest (mSv = DLPx0.017). Heart rate range and mean heart rate, expressed in beats per minute (bpm) of each individual during CTCA, were also provided by the system. Statistical analysis of effective dose and heart rate data was performed by using Pearson correlation coefficient and two-sample t-test. Mean HR and effective dose were found to have a borderline positive relationship. Individuals with a mean HR >65 bpm observed to receive a statistically significant higher effective dose as compared to those with a mean HR ≤65 bpm. Moreover, a strong correlation between effective dose and variability of HR of more than 20 bpm was observed. Dual-source CT scanners are considered to have the capability to provide diagnostic examinations even with high HR and arrhythmias. However, it is desirable to keep the mean heart rate below 65 bpm and heart rate fluctuation less than 20 bpm in order to reduce the radiation exposure.

Bulk density of an alfisol under cultivation systems in a long-term experiment evaluated with gamma ray computed tomography

International Nuclear Information System (INIS)

Bamberg, Adilson Luis; Silva, Thiago Rech da; Pauletto, Eloy Antonio; Pinto, Luiz Fernando Spinelli; Lima, Ana Claudia Rodrigues de; Timm, Luis Carlos

2009-01-01

The sustainability of irrigated rice (Oryza sativa L.) in lowland soils is based on the use of crop rotation and succession, which are essential for the control of red and black rice. The effects on the soil properties deserve studies, particularly on soil compaction. The objective of this study was to identify compacted layers in an albaqualf under different cultivation and tillage systems, by evaluating the soil bulk density (Ds) with Gamma Ray Computed Tomography (TC). The analysis was carried out in a long-term experiment, from 1985 to 2004, at an experimental station of EMBRAPA Clima Temperado, Capao do Leao, RS, Brazil, in a random block design with seven treatments, with four replications (T1 - one year rice with conventional tillage followed by two years fallow; T2 - continuous rice under conventional tillage; T4 - rice and soybean (Glycine Max L.) rotation under conventional tillage; T5 - rice, soybean and corn (Zea maize L.) rotation under conventional tillage; T6 - rice under no-tillage in the summer in succession to rye-grass (Lolium multiflorum L.) in the winter; T7 - rice under no-tillage and soybean under conventional tillage rotation; T8 - control: uncultivated soil). The Gamma Ray Computed Tomography method did not identify compacted soil layers under no tillage rice in succession to rye-grass; two fallow years in the irrigated rice production system did not prevent the formation of a compacted layer at the soil surface; and in the rice, soybean and corn rotation under conventional tillage two compacted layers were identified (0.0 to 1.5 cm and 11 to 14 cm), indicating that they may restrict the agricultural production in this cultivation system on Albaqualf soils. (author)

The Effect of Bulk Depth and Irradiation Time on the Surface Hardness and Degree of Cure of Bulk-Fill Composites

Directory of Open Access Journals (Sweden)

Farahat F

2016-09-01

Full Text Available Statement of Problem: For many years, application of the composite restoration with a thickness less than 2 mm for achieving the minimum polymerization contraction and stress has been accepted as a principle. But through the recent development in dental material a group of resin based composites (RBCs called Bulk Fill is introduced whose producers claim the possibility of achieving a good restoration in bulks with depths of 4 or even 5 mm. Objectives: To evaluate the effect of irradiation times and bulk depths on the degree of cure (DC of a bulk fill composite and compare it with the universal type. Materials and Methods: This study was conducted on two groups of dental RBCs including Tetric N Ceram Bulk Fill and Tetric N Ceram Universal. The composite samples were prepared in Teflon moulds with a diameter of 5 mm and height of 2, 4 and 6 mm. Then, half of the samples in each depth were cured from the upper side of the mould for 20s by LED light curing unit. The irradiation time for other specimens was 40s. After 24 hours of storage in distilled water, the microhardness of the top and bottom of the samples was measured using a Future Tech (Japan- Model FM 700 Vickers hardness testing machine. Data were analyzed statistically using the one and multi way ANOVAand Tukey’s test (p = 0.050. Results: The DC of Tetric N Ceram Bulk Fill in defined irradiation time and bulk depth was significantly more than the universal type (p < 0.001. Also, the DC of both composites studied was significantly (p < 0.001 reduced by increasing the bulk depths. Increasing the curing time from 20 to 40 seconds had a marginally significant effect (p ≤ 0.040 on the DC of both bulk fill and universal studied RBC samples. Conclusions: The DC of the investigated bulk fill composite was better than the universal type in all the irradiation times and bulk depths. The studied universal and bulk fill RBCs had an appropriate DC at the 2 and 4 mm bulk depths respectively and

A history of slide rules for blackbody radiation computations

Science.gov (United States)

Johnson, R. Barry; Stewart, Sean M.

2012-10-01

During the Second World War the importance of utilizing detection devices capable of operating in the infrared portion of the electromagnetic spectrum was firmly established. Up until that time, laboriously constructed tables for blackbody radiation needed to be used in calculations involving the amount of radiation radiated within a given spectral region or for other related radiometric quantities. To rapidly achieve reasonably accurate calculations of such radiometric quantities, a blackbody radiation calculator was devised in slide rule form first in Germany in 1944 and soon after in England and the United States. In the immediate decades after its introduction, the radiation slide rule was widely adopted and recognized as a useful and important tool for engineers and scientists working in the infrared field. It reached its pinnacle in the United States in 1970 in a rule introduced by Electro Optical Industries, Inc. With the onset in the latter half of the 1970s of affordable, hand-held electronic calculators, the impending demise of the radiation slide rule was evident. No longer the calculational device of choice, the radiation slide rule all but disappeared within a few short years. Although today blackbody radiation calculations can be readily accomplished using anything from a programmable pocket calculator upwards, with each device making use of a wide variety of numerical approximations to the integral of Planck's function, radiation slide rules were in the early decades of infrared technology the definitive "workhorse" for those involved in infrared systems design and engineering. This paper presents a historical development of radiation slide rules with many versions being discussed.

Cherenkov radiation by an electron bunch that moves in a vacuum above a left-handed material

International Nuclear Information System (INIS)

Averkov, Yu.O.; Yakovenko, V.M.

2005-01-01

Cherenkov radiation by a nonrelativistic electron bunch that moves above an interface of a vacuum-left-handed material has been investigated theoretically. The electron density of the bunch is described by a Gauss distribution. Cherenkov radiation for the frequency range where the refractive index is negative is shown to lead to simultaneous excitation of both bulk and surface electromagnetic waves over one and the same frequency range. In this case the wave vector magnitude in the plane of the interface of surface electromagnetic waves is larger than the corresponding wave vector magnitude of bulk electromagnetic waves. The energy flows in a left-handed material have been calculated. The spectral density and the radiation pattern have been investigated

Effectiveness of Bismuth Shield to Reduce Eye Lens Radiation Dose Using the Photoluminescence Dosimetry in Computed Tomography

International Nuclear Information System (INIS)

Jung, Mi Young; Kweon, Dae Cheol; Kwon, Soo Il

2009-01-01

The purpose of our study was to determine the eye radiation dose when performing routine multi-detector computed tomography (MDCT). We also evaluated dose reduction and the effect on image quality of using a bismuth eye shield when performing head MDCT. Examinations were performed with a 64MDCT scanner. To compare the shielded/unshielded lens dose, the examination was performed with and without bismuth shielding in anthropomorphic phantom. To determine the average lens radiation dose, we imaged an anthropomorphic phantom into which calibrated photoluminescence glass dosimeter (PLD) were placed to measure the dose to lens. The phantom was imaged using the same protocol. Radiation doses to the lens with and without the lens shielding were measured and compared using the Student t test. In the qualitative evaluation of the MDCT scans, all were considered to be of diagnostic quality. We did not see any differences in quality between the shielded and unshielded brain. The mean radiation doses to the eye with the shield and to those without the shield were 21.54 versus 10.46 mGy, respectively. The lens shield enabled a 51.3% decrease in radiation dose to the lens. Bismuth in-plane shielding for routine eye and head MDCT decreased radiation dose to the lens without qualitative changes in image quality. The other radiosensitive superficial organs specifically must be protected with shielding.

Prior image constrained scatter correction in cone-beam computed tomography image-guided radiation therapy.

Science.gov (United States)

Brunner, Stephen; Nett, Brian E; Tolakanahalli, Ranjini; Chen, Guang-Hong

2011-02-21

X-ray scatter is a significant problem in cone-beam computed tomography when thicker objects and larger cone angles are used, as scattered radiation can lead to reduced contrast and CT number inaccuracy. Advances have been made in x-ray computed tomography (CT) by incorporating a high quality prior image into the image reconstruction process. In this paper, we extend this idea to correct scatter-induced shading artifacts in cone-beam CT image-guided radiation therapy. Specifically, this paper presents a new scatter correction algorithm which uses a prior image with low scatter artifacts to reduce shading artifacts in cone-beam CT images acquired under conditions of high scatter. The proposed correction algorithm begins with an empirical hypothesis that the target image can be written as a weighted summation of a series of basis images that are generated by raising the raw cone-beam projection data to different powers, and then, reconstructing using the standard filtered backprojection algorithm. The weight for each basis image is calculated by minimizing the difference between the target image and the prior image. The performance of the scatter correction algorithm is qualitatively and quantitatively evaluated through phantom studies using a Varian 2100 EX System with an on-board imager. Results show that the proposed scatter correction algorithm using a prior image with low scatter artifacts can substantially mitigate scatter-induced shading artifacts in both full-fan and half-fan modes.

Diagnostic accuracy of computed tomography using lower doses of radiation for patients with Crohn's disease.

LENUS (Irish Health Repository)

Craig, Orla

2012-08-01

Magnetic resonance and ultrasonography have increasing roles in the initial diagnosis of Crohn\\'s disease, but computed tomography (CT) with positive oral contrast agents is most frequently used to identify those with acute extramural complications. However, CT involves exposure of patients to radiation. We prospectively compared the diagnostic accuracy of low-dose CT (at a dose comparable to that used to obtain an abdominal radiograph) with conventional-dose CT in patients with active Crohn\\'s disease.

78 FR 72841 - List of Bulk Drug Substances That May Be Used in Pharmacy Compounding; Bulk Drug Substances That...

Science.gov (United States)

2013-12-04

.... FDA-2013-N-1525] List of Bulk Drug Substances That May Be Used in Pharmacy Compounding; Bulk Drug... proposed rule to list bulk drug substances used in pharmacy compounding and preparing to develop a list of... Formulary monograph, if a monograph exists, and the United States Pharmacopoeia chapter on pharmacy...

Single-source gamma radiation procedures for improved calibration and measurements in porous media

International Nuclear Information System (INIS)

Oostrom, M.; Hofstee, C.; Dane, H.; Lenhard, R.J.

1998-01-01

When dual-energy gamma radiation systems are employed for measurements in porous media, count rates from both sources are often used to compute parameter values. However, for several applications, the count rates of just one source are insufficient. These applications include the determination of volumetric liquid content values in two-liquid systems and salt concentration values in water-saturated porous media. Single-energy gamma radiation procedures for three applications are described in this paper. Through an error analysis, single-source procedures are shown to reduce the probable error in the determinations considerably. Example calculations and simple column experiments were conducted for each application to compare the performance of the new single-source and standard dual-source methods. In all cases, the single-source methods provided more reliable data than the traditional dual-source methods. In addition, a single-source calibration procedure is proposed to determine incident count rates indirectly. This procedure, which requires packing under saturated conditions, can be used in all single- and dual-source applications and yields accurate porosity and dry bulk density values

Microdefects in an as-grown Czochralski silicon crystal studied by synchrotron radiation section topography with aid of computer simulation

International Nuclear Information System (INIS)

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)

Ionizing radiation for insect control in grain and grain products

International Nuclear Information System (INIS)

Tilton, E.W.; Brower, J.H.

1987-01-01

A technical review summarizes and discusses information on various aspects of the use of ionizing radiation for the control of insect infestation in grains and grain products. Topics include: the effects of ionizing radiation on insects infesting stored-grain products; the 2 main types of irradiators (electron accelerators; radioisotopes (e.g.: Co-60; Cs-137); dosimetry systems and methodology; variations in radiation resistance by stored-product pests; the proper selection of radiation dose; the effects of combining various treatments (temperature, infrared/microwave radiation, hypoxia, chemicals) with ionizing radiation; sublethal radiation for controlling bulk grain insects; the feeding capacity of irradiated insects; the susceptibility of insecticide-resistant insects to ionizing radiation; and the possible resistance of insects to ionizing radiation. Practical aspects of removing insects from irradiated grain also are discussed

Vinyl acetate polymerization by ionizing radiation

International Nuclear Information System (INIS)

Mesquita, Andrea Cercan

2002-01-01

The aim of this work is the synthesis and characterization of the poly(vinyl acetate) using the ionizing radiation. Six polymerizations of vinyl acetate were carried out using three techniques of polymerization: in bulk, emulsion and solution. In the technique of solution polymerization were used two solvents, the alcohol ethyl and the methylethylketone, in two proportions 1:0.5 and 1:1 related to the monomer. The solutions were irradiated with gamma rays from a 60 Co source, with dose rate between 5.25 kGy/h and 6.26 kGy/h. The polymers obtained were characterized by Fourier Transform Infrared Spectroscopy (FTIR). The glass transition temperature (Tg) was investigated by Differential Scanning Calorimeter (DSC). The molecular weight was analyzed by the technique of Gel Permeation Chromatography (GPC). Tests of density, hardness and Vicat softening temperature were carried out. The infrared spectroscopy and others results confirmed that the polymers obtained by polymerization of vinyl acetate in bulk, emulsion and solution, using ionizing radiation, really correspond at poly(vinyl acetate). (author)

Rice hulls a new bulking component for larval rearing of the mediterranean fruit fly, ceratitis capitata wied

International Nuclear Information System (INIS)

Wakid, A.M.; El-Kholy, E.M.S.; Shoman, A.A.; El-Akhdar, E.A.H.; Abdel Rahman, H.A.

1998-01-01

Rice hulls as a new bulking component for the larval rearing of the mediterranean fruit fly, ceratitis capitata wied. Was tested in the laboratory; and 4 formulas of rice hulls and wheat bran were evaluated biologically and financially. When rice hulls and wheat bran were mixed in the ratio of 3:1, all biological aspects and response to gamma radiation (90 Gy) of the produced adults were normal except for male fertility that decreased by about 13% of that of the bran medium (control); while male mating competitiveness was increased. When rice hulls were used without bran, only adult emergece and female fecundity were decreased by about 2% and 20%, respectively as compared to control medium (totally wheat bran); while larval duration increased by one day. The fourth formula consisting of wheat bran and rice hulls in the ratio of 1:1 showed the least favourite bulking component. Calculations showed that one million pupal production costed $26.6,22.2, 20.2 and 21.4 for the bulking ratios (hulls : bran) 0.1, 1:1, 3:1 and 1:0,respectively

Soil structure changes evaluated with computed tomography

International Nuclear Information System (INIS)

Pires, Luiz Fernando

2010-01-01

The objective of this work was to evaluate in millimetric scale changes in soil bulk density and porosity, using the gamma-ray computed tomography in soil samples with disturbed structure due to wetting and drying (W-D) cycles. Soil samples with 98.1 cm 3 were sieved using a 2 mm mesh and homogeneously packed in PVC cylinders. Soil samples were submitted to 1, 2, and 3 W-D cycles. Control samples were not submitted to W-D cycles. After repetitions of W-D cycles, soil sample porosity decreased and soil layers became denser. Computed tomography allowed a continuous analysis of soil bulk density and also soil porosity along millimetric (0.08 cm) layers, what cannot be provided by traditional methods used in soil physics. (author)

Longitudinal and bulk viscosities of expanded rubidium

International Nuclear Information System (INIS)

Zaheri, Ali Hossein Mohammad; Srivastava, Sunita; Tankeshwar, K

2003-01-01

First three non-vanishing sum rules for the bulk and longitudinal stress auto-correlation functions have been evaluated for liquid Rb at six thermodynamic states along the liquid-vapour coexistence curve. The Mori memory function formalism and the frequency sum rules have been used to calculate bulk and longitudinal viscosities. The results thus obtained for the ratio of bulk viscosity to shear viscosity have been compared with experimental and other theoretical predictions wherever available. The values of the bulk viscosity have been found to be more than the corresponding values of the shear viscosity for all six thermodynamic states investigated here

Modeling of clouds and radiation for development of parameterizations for general circulation models

International Nuclear Information System (INIS)

Westphal, D.; Toon, B.; Jensen, E.; Kinne, S.; Ackerman, A.; Bergstrom, R.; Walker, A.

1994-01-01

Atmospheric Radiation Measurement (ARM) Program research at NASA Ames Research Center (ARC) includes radiative transfer modeling, cirrus cloud microphysics, and stratus cloud modeling. These efforts are designed to provide the basis for improving cloud and radiation parameterizations in our main effort: mesoscale cloud modeling. The range of non-convective cloud models used by the ARM modeling community can be crudely categorized based on the number of predicted hydrometers such as cloud water, ice water, rain, snow, graupel, etc. The simplest model has no predicted hydrometers and diagnoses the presence of clouds based on the predicted relative humidity. The vast majority of cloud models have two or more predictive bulk hydrometers and are termed either bulk water (BW) or size-resolving (SR) schemes. This study compares the various cloud models within the same dynamical framework, and compares results with observations rather than climate statistics

Radiation Exposure of Passengers to Cosmic Radiation

International Nuclear Information System (INIS)

Salah El-Din, T.; Gomaa, M.A.; Sallah, N.

2010-01-01

The main aim of the present study is to review exposure of Egyptian passengers and occupational workers to cosmic radiation during their work. Computed effective dose of passengers by computer code CARI-6 using during either short route, medium route or long route as well as recommended allowed number of flights per year

Sound transmission analysis of plate structures using the finite element method and elementary radiator approach with radiator error index

DEFF Research Database (Denmark)

Jung, Jaesoon; Kook, Junghwan; Goo, Seongyeol

2017-01-01

combines the FEM and Elementary Radiator Approach (ERA) is proposed. The FE-ERA method analyzes the vibrational response of the plate structure excited by incident sound using FEM and then computes the transmitted acoustic pressure from the vibrating plate using ERA. In order to improve the accuracy...... and efficiency of the FE-ERA method, a novel criterion for the optimal number of elementary radiators is proposed. The criterion is based on the radiator error index that is derived to estimate the accuracy of the computation with used number of radiators. Using the proposed criterion a radiator selection method...... is presented for determining the optimum number of radiators. The presented radiator selection method and the FE-ERA method are combined to improve the computational accuracy and efficiency. Several numerical examples that have been rarely addressed in previous studies, are presented with the proposed method...

Interstitial solute transport in 3D reconstructed neuropil occurs by diffusion rather than bulk flow.

Science.gov (United States)

Holter, Karl Erik; Kehlet, Benjamin; Devor, Anna; Sejnowski, Terrence J; Dale, Anders M; Omholt, Stig W; Ottersen, Ole Petter; Nagelhus, Erlend Arnulf; Mardal, Kent-André; Pettersen, Klas H

2017-09-12

The brain lacks lymph vessels and must rely on other mechanisms for clearance of waste products, including amyloid [Formula: see text] that may form pathological aggregates if not effectively cleared. It has been proposed that flow of interstitial fluid through the brain's interstitial space provides a mechanism for waste clearance. Here we compute the permeability and simulate pressure-mediated bulk flow through 3D electron microscope (EM) reconstructions of interstitial space. The space was divided into sheets (i.e., space between two parallel membranes) and tunnels (where three or more membranes meet). Simulation results indicate that even for larger extracellular volume fractions than what is reported for sleep and for geometries with a high tunnel volume fraction, the permeability was too low to allow for any substantial bulk flow at physiological hydrostatic pressure gradients. For two different geometries with the same extracellular volume fraction the geometry with the most tunnel volume had [Formula: see text] higher permeability, but the bulk flow was still insignificant. These simulation results suggest that even large molecule solutes would be more easily cleared from the brain interstitium by diffusion than by bulk flow. Thus, diffusion within the interstitial space combined with advection along vessels is likely to substitute for the lymphatic drainage system in other organs.

Comparison of Diagnostic Accuracy of Radiation Dose-Equivalent Radiography, Multidetector Computed Tomography and Cone Beam Computed Tomography for Fractures of Adult Cadaveric Wrists.

Science.gov (United States)

Neubauer, Jakob; Benndorf, Matthias; Reidelbach, Carolin; Krauß, Tobias; Lampert, Florian; Zajonc, Horst; Kotter, Elmar; Langer, Mathias; Fiebich, Martin; Goerke, Sebastian M

2016-01-01

To compare the diagnostic accuracy of radiography, to radiography equivalent dose multidetector computed tomography (RED-MDCT) and to radiography equivalent dose cone beam computed tomography (RED-CBCT) for wrist fractures. As study subjects we obtained 10 cadaveric human hands from body donors. Distal radius, distal ulna and carpal bones (n = 100) were artificially fractured in random order in a controlled experimental setting. We performed radiation dose equivalent radiography (settings as in standard clinical care), RED-MDCT in a 320 row MDCT with single shot mode and RED-CBCT in a device dedicated to musculoskeletal imaging. Three raters independently evaluated the resulting images for fractures and the level of confidence for each finding. Gold standard was evaluated by consensus reading of a high-dose MDCT. Pooled sensitivity was higher in RED-MDCT with 0.89 and RED-MDCT with 0.81 compared to radiography with 0.54 (P = radiography (P radiography. Readers are more confident in their reporting with the cross sectional modalities. Dose equivalent cross sectional computed tomography of the wrist could replace plain radiography for fracture diagnosis in the long run.

Locality, bulk equations of motion and the conformal bootstrap

Energy Technology Data Exchange (ETDEWEB)

Kabat, Daniel [Department of Physics and Astronomy, Lehman College, City University of New York,250 Bedford Park Blvd. W, Bronx NY 10468 (United States); Lifschytz, Gilad [Department of Mathematics, Faculty of Natural Science, University of Haifa,199 Aba Khoushy Ave., Haifa 31905 (Israel)

2016-10-18

We develop an approach to construct local bulk operators in a CFT to order 1/N{sup 2}. Since 4-point functions are not fixed by conformal invariance we use the OPE to categorize possible forms for a bulk operator. Using previous results on 3-point functions we construct a local bulk operator in each OPE channel. We then impose the condition that the bulk operators constructed in different channels agree, and hence give rise to a well-defined bulk operator. We refer to this condition as the “bulk bootstrap.” We argue and explicitly show in some examples that the bulk bootstrap leads to some of the same results as the regular conformal bootstrap. In fact the bulk bootstrap provides an easier way to determine some CFT data, since it does not require knowing the form of the conformal blocks. This analysis clarifies previous results on the relation between bulk locality and the bootstrap for theories with a 1/N expansion, and it identifies a simple and direct way in which OPE coefficients and anomalous dimensions determine the bulk equations of motion to order 1/N{sup 2}.

Applications and modelling of bulk HTSs in brushless ac machines

International Nuclear Information System (INIS)

Barnes, G.J.

2000-01-01

The use of high temperature superconducting material in its bulk form for engineering applications is attractive due to the large power densities that can be achieved. In brushless electrical machines, there are essentially four properties that can be exploited; their hysteretic nature, their flux shielding properties, their ability to trap large flux densities and their ability to produce levitation. These properties translate to hysteresis machines, reluctance machines, trapped-field synchronous machines and linear motors respectively. Each one of these machines is addressed separately and computer simulations that reveal the current and field distributions within the machines are used to explain their operation. (author)

Correlation of radiation dose and heart rate in dual-source computed tomography coronary angiography

International Nuclear Information System (INIS)

Laspas, Fotios; Roussakis, Arkadios; Kritikos, Nikolaos; Efthimiadou, Roxani; Kehagias, Dimitrios; Andreou, John; Tsantioti, Dimitra

2011-01-01

Background: Computed tomography coronary angiography (CTCA) has been widely used since the introduction of 64-slice scanners and dual-source CT technology, but the relatively high radiation dose remains a major concern. Purpose: To evaluate the relationship between radiation exposure and heart rate (HR), in dual-source CTCA. Material and Methods: Data from 218 CTCA examinations, performed with a dual-source 64-slices scanner, were statistically evaluated. Effective radiation dose, expressed in mSv, was calculated as the product of the dose-length product (DLP) times a conversion coefficient for the chest (mSv = DLPx0.017). Heart rate range and mean heart rate, expressed in beats per minute (bpm) of each individual during CTCA, were also provided by the system. Statistical analysis of effective dose and heart rate data was performed by using Pearson correlation coefficient and two-sample t-test. Results: Mean HR and effective dose were found to have a borderline positive relationship. Individuals with a mean HR >65 bpm observed to receive a statistically significant higher effective dose as compared to those with a mean HR =65 bpm. Moreover, a strong correlation between effective dose and variability of HR of more than 20 bpm was observed. Conclusion: Dual-source CT scanners are considered to have the capability to provide diagnostic examinations even with high HR and arrhythmias. However, it is desirable to keep the mean heart rate below 65 bpm and heart rate fluctuation less than 20 bpm in order to reduce the radiation exposure

A Computational Fluid Dynamics Study of Turbulence, Radiation, and Combustion Models for Natural Gas Combustion Burner

Directory of Open Access Journals (Sweden)

Yik Siang Pang

2018-01-01

Full Text Available This paper presents a Computational Fluid Dynamics (CFD study of a natural gas combustion burner focusing on the effect of combustion, thermal radiation and turbulence models on the temperature and chemical species concentration fields. The combustion was modelled using the finite rate/eddy dissipation (FR/EDM and partially premixed flame models. Detailed chemistry kinetics CHEMKIN GRI-MECH 3.0 consisting of 325 reactions was employed to model the methane combustion. Discrete ordinates (DO and spherical harmonics (P1 model were employed to predict the thermal radiation. The gas absorption coefficient dependence on the wavelength is resolved by the weighted-sum-of-gray-gases model (WSGGM. Turbulence flow was simulated using Reynolds-averaged Navier-Stokes (RANS based models. The findings showed that a combination of partially premixed flame, P1 and standard k-ε (SKE gave the most accurate prediction with an average deviation of around 7.8% of combustion temperature and 15.5% for reactant composition (methane and oxygen. The results show the multi-step chemistry in the partially premixed model is more accurate than the two-step FR/EDM. Meanwhile, inclusion of thermal radiation has a minor effect on the heat transfer and species concentration. SKE turbulence model yielded better prediction compared to the realizable k-ε (RKE and renormalized k-ε (RNG. The CFD simulation presented in this work may serve as a useful tool to evaluate a performance of a natural gas combustor. Copyright © 2018 BCREC Group. All rights reserved Received: 26th July 2017; Revised: 9th October 2017; Accepted: 30th October 2017; Available online: 22nd January 2018; Published regularly: 2nd April 2018 How to Cite: Pang, Y.S., Law, W.P., Pung, K.Q., Gimbun, J. (2018. A Computational Fluid Dynamics Study of Turbulence, Radiation, and Combustion Models for Natural Gas Combustion Burner. Bulletin of Chemical Reaction Engineering & Catalysis, 13 (1: 155-169 (doi:10.9767/bcrec

The UF family of reference hybrid phantoms for computational radiation dosimetry

International Nuclear Information System (INIS)

Lee, Choonsik; Lodwick, Daniel; Hurtado, Jorge; Pafundi, Deanna; Williams, Jonathan L; Bolch, Wesley E

2010-01-01

Computational human phantoms are computer models used to obtain dose distributions within the human body exposed to internal or external radiation sources. In addition, they are increasingly used to develop detector efficiencies for in vivo whole-body counters. Two classes of computational human phantoms have been widely utilized for dosimetry calculation: stylized and voxel phantoms that describe human anatomy through mathematical surface equations and 3D voxel matrices, respectively. Stylized phantoms are flexible in that changes to organ position and shape are possible given avoidance of region overlap, while voxel phantoms are typically fixed to a given patient anatomy, yet can be proportionally scaled to match individuals of larger or smaller stature, but of equivalent organ anatomy. Voxel phantoms provide much better anatomical realism as compared to stylized phantoms which are intrinsically limited by mathematical surface equations. To address the drawbacks of these phantoms, hybrid phantoms based on non-uniform rational B-spline (NURBS) surfaces have been introduced wherein anthropomorphic flexibility and anatomic realism are both preserved. Researchers at the University of Florida have introduced a series of hybrid phantoms representing the ICRP Publication 89 reference newborn, 15 year, and adult male and female. In this study, six additional phantoms are added to the UF family of hybrid phantoms-those of the reference 1 year, 5 year and 10 year child. Head and torso CT images of patients whose ages were close to the targeted ages were obtained under approved protocols. Major organs and tissues were segmented from these images using an image processing software, 3D-DOCTOR(TM). NURBS and polygon mesh surfaces were then used to model individual organs and tissues after importing the segmented organ models to the 3D NURBS modeling software, Rhinoceros(TM). The phantoms were matched to four reference datasets: (1) standard anthropometric data, (2) reference

Microthrix parvicella abundance associates with activated sludge settling velocity and rheology - Quantifying and modelling filamentous bulking.

Science.gov (United States)

Wágner, Dorottya S; Ramin, Elham; Szabo, Peter; Dechesne, Arnaud; Plósz, Benedek Gy

2015-07-01

The objective of this work is to identify relevant settling velocity and rheology model parameters and to assess the underlying filamentous microbial community characteristics that can influence the solids mixing and transport in secondary settling tanks. Parameter values for hindered, transient and compression settling velocity functions were estimated by carrying out biweekly batch settling tests using a novel column setup through a four-month long measurement campaign. To estimate viscosity model parameters, rheological experiments were carried out on the same sludge sample using a rotational viscometer. Quantitative fluorescence in-situ hybridisation (qFISH) analysis, targeting Microthrix parvicella and phylum Chloroflexi, was used. This study finds that M. parvicella - predominantly residing inside the microbial flocs in our samples - can significantly influence secondary settling through altering the hindered settling velocity and yield stress parameter. Strikingly, this is not the case for Chloroflexi, occurring in more than double the abundance of M. parvicella, and forming filaments primarily protruding from the flocs. The transient and compression settling parameters show a comparably high variability, and no significant association with filamentous abundance. A two-dimensional, axi-symmetrical computational fluid dynamics (CFD) model was used to assess calibration scenarios to model filamentous bulking. Our results suggest that model predictions can significantly benefit from explicitly accounting for filamentous bulking by calibrating the hindered settling velocity function. Furthermore, accounting for the transient and compression settling velocity in the computational domain is crucial to improve model accuracy when modelling filamentous bulking. However, the case-specific calibration of transient and compression settling parameters as well as yield stress is not necessary, and an average parameter set - obtained under bulking and good settling

Spectral tuning of near-field radiative heat transfer by graphene-covered metasurfaces

Science.gov (United States)

Zheng, Zhiheng; Wang, Ao; Xuan, Yimin

2018-03-01

When two gratings are respectively covered by a layer of graphene sheet, the near-field radiative heat transfer between two parallel gratings made of silica (SiO2) could be greatly improved. As the material properties of doped silicon (n-type doping concentration is 1020 cm-3, marked as Si-20) and SiO2 differ greatly, we theoretically investigate the near-field radiative heat transfer between two parallel graphene-covered gratings made of Si-20 to explore some different phenomena, especially for modulating the spectral properties. The radiative heat flux between two parallel bulks made of Si-20 can be enhanced by using gratings instead of bulks. When the two gratings are respectively covered by a layer of graphene sheet, the radiative heat flux between two gratings made of Si-20 can be further enhanced. By tuning graphene chemical potential μ and grating filling factor f, due to the interaction between surface plasmon polaritons (SPPs) of graphene sheets and grating structures, the spectral properties of the radiative heat flux between two parallel graphene-covered gratings can be effectively regulated. This work will develop and supplement the effects of materials on the near-field radiative heat transfer for this kind of system configuration, paving a way to modulate the spectral properties of near-field radiative heat transfer.

Contribution of radiation chemistry to cluster science

International Nuclear Information System (INIS)

Belloni, J.

2006-01-01

Nanoclusters are small objects made of a few atoms, with a size of a few nanometers at most, which constitute a state of matter, named mesoscopic, intermediary between the atom and the bulk metal. In the 70's, radiation chemistry experiments have demonstrated that metal clusters exhibited indeed, due to their very small size, specific properties distinct from the bulk metal. The properties, physical and chemical, change with the number of atoms they contain. Their optical absorption spectrum, for example, as well as their redox potential, depends on the nuclearity, and also on the environment. Radiation chemistry methods have been proven to be of high potentiality to induce small and size-monodispersed metal clusters, as nanocolloids or supported on various materials. Pulse radiolysis provides the means to study the dynamics of nucleation and growth of clusters, monoand bi-metallic, from the monomers to the stable nanoparticle and to observe directly their reactivity, especially to determine during the growth their nuclearity-dependent properties, such as the redox potential. These are of crucial importance for the understanding of the mechanism of the cluster growth itself, in the radiation-induced as well as in the chemical or photochemical reduction processes, and also of the mechanism of certain catalytic reactions. (authors)

A web-based remote radiation treatment planning system using the remote desktop function of a computer operating system: a preliminary report.

Science.gov (United States)

Suzuki, Keishiro; Hirasawa, Yukinori; Yaegashi, Yuji; Miyamoto, Hideki; Shirato, Hiroki

2009-01-01

We developed a web-based, remote radiation treatment planning system which allowed staff at an affiliated hospital to obtain support from a fully staffed central institution. Network security was based on a firewall and a virtual private network (VPN). Client computers were installed at a cancer centre, at a university hospital and at a staff home. We remotely operated the treatment planning computer using the Remote Desktop function built in to the Windows operating system. Except for the initial setup of the VPN router, no special knowledge was needed to operate the remote radiation treatment planning system. There was a time lag that seemed to depend on the volume of data traffic on the Internet, but it did not affect smooth operation. The initial cost and running cost of the system were reasonable.

Bulk temperature measurement in thermally striped pipe flows

International Nuclear Information System (INIS)

Lemure, N.; Olvera, J.R.; Ruggles, A.E.

1995-12-01

The hot leg flows in some Pressurized Water Reactor (PWR) designs have a temperature distribution across the pipe cross-section. This condition is often referred to as a thermally striped flow. Here, the bulk temperature measurement of pipe flows with thermal striping is explored. An experiment is conducted to examine the feasibility of using temperature measurements on the external surface of the pipe to estimate the bulk temperature of the flow. Simple mixing models are used to characterize the development of the temperature profile in the flow. Simple averaging techniques and Backward Propagating Neural Net are used to predict bulk temperature from the external temperature measurements. Accurate bulk temperatures can be predicted. However, some temperature distributions in the flow effectively mask the bulk temperature from the wall and cause significant error in the bulk temperature predicted using this technique

Transfer points of belt conveyors operating with unfavorable bulk

Energy Technology Data Exchange (ETDEWEB)

Goehring, H [Technische Universitaet, Dresden (German Democratic Republic)

1989-06-01

Describes design of belt conveyor chutes that transfer bulk of surface mines from one conveyor to another. Conveyor belt velocity is a significant parameter. Unfavorable chute design may lead to bulk flow congestion, bulk velocity losses etc. The bulk flow process is analyzed, bulk flow velocities, belt inclinations and bulk feeding from 2 conveyors into one chute are taken into account. Conventional chutes have parabolic belt impact walls. An improved version with divided impact walls is proposed that maintains a relatively high bulk velocity, reduces friction at chute walls and decreases wear and dirt build-up. Design of the improved chute is explained. It is built to adapt to existing structures without major modifications. The angle between 2 belt conveyors can be up to 90 degrees, the best bulk transfer is noted at conveyor angles below 60 degrees. Various graphs and schemes are provided. 6 refs.

Radiation damage in silicon detectors

CERN Document Server

Lindström, G

2003-01-01

Radiation damage effects in silicon detectors under severe hadron and gamma-irradiation are surveyed, focusing on bulk effects. Both macroscopic detector properties (reverse current, depletion voltage and charge collection) as also the underlying microscopic defect generation are covered. Basic results are taken from the work done in the CERN-RD48 (ROSE) collaboration updated by results of recent work. Preliminary studies on the use of dimerized float zone and Czochralski silicon as detector material show possible benefits. An essential progress in the understanding of the radiation-induced detector deterioration had recently been achieved in gamma irradiation, directly correlating defect analysis data with the macroscopic detector performance.

COMPUTATIONAL MODEL TAHANAN KAPAL UNTUK MENENTUKAN KEBUTUHAN DAYA KAPAL BULK CARRIER 8664 DWT

Directory of Open Access Journals (Sweden)

Erik Sugianto

2018-02-01

Full Text Available Faktor utama dalam menentukan daya mesin kapal adalah tahanan kapal. Umumnya, tahanan kapal dihitung menggunakan percobaan model pada towing tank. Namun biaya yang diperlukan sangat besar. Penelitian ini bertujuan menentukan tahanan total kapal dan memperkiraan kebutuhan daya mesin kapal bulk carrier 8664 DWT. Kapal dimodelkan menggunakan software perkapalan, kemudian perhitungan tahanan kapal dan kebutuhan daya kapal dilakukan. Selain itu dilakukan validasi hasil dengan perhitungan matematis Holtrop dan analisa perbandingan hasil dengan penelitian sebelumnya. Hasil analisa untuk kecepatan dinas maksimal 14 knots menunjukan tahanan total kapal adalah 286. 75 kN dan kebutuhan dayanya adalah 2950.31 kW. Sedangkan dengan perhitungan matematis Holtrop dihasilkan tahanan total 256.59 kN, ini terdapat selisih 10.52% dengan hasil permodelan komputer.Kata kunci: tahanan, model, daya, kapal

Computer codes in nuclear safety, radiation transport and dosimetry; Les codes de calcul en radioprotection, radiophysique et dosimetrie

Energy Technology Data Exchange (ETDEWEB)

Bordy, J M; Kodeli, I; Menard, St; Bouchet, J L; Renard, F; Martin, E; Blazy, L; Voros, S; Bochud, F; Laedermann, J P; Beaugelin, K; Makovicka, L; Quiot, A; Vermeersch, F; Roche, H; Perrin, M C; Laye, F; Bardies, M; Struelens, L; Vanhavere, F; Gschwind, R; Fernandez, F; Quesne, B; Fritsch, P; Lamart, St; Crovisier, Ph; Leservot, A; Antoni, R; Huet, Ch; Thiam, Ch; Donadille, L; Monfort, M; Diop, Ch; Ricard, M

2006-07-01

The purpose of this conference was to describe the present state of computer codes dedicated to radiation transport or radiation source assessment or dosimetry. The presentations have been parted into 2 sessions: 1) methodology and 2) uses in industrial or medical or research domains. It appears that 2 different calculation strategies are prevailing, both are based on preliminary Monte-Carlo calculations with data storage. First, quick simulations made from a database of particle histories built though a previous Monte-Carlo simulation and secondly, a neuronal approach involving a learning platform generated through a previous Monte-Carlo simulation. This document gathers the slides of the presentations.

Heavy ion linear accelerator for radiation damage studies of materials

Energy Technology Data Exchange (ETDEWEB)

Kutsaev, Sergey V.; Mustapha, Brahim; Ostroumov, Peter N.; Nolen, Jerry; Barcikowski, Albert; Pellin, Michael; Yacout, Abdellatif

2017-03-01

A new eXtreme MATerial (XMAT) research facility is being proposed at Argonne National Laboratory to enable rapid in situ mesoscale bulk analysis of ion radiation damage in advanced materials and nuclear fuels. This facility combines a new heavy-ion accelerator with the existing high-energy X-ray analysis capability of the Argonne Advanced Photon Source. The heavy-ion accelerator and target complex will enable experimenters to emulate the environment of a nuclear reactor making possible the study of fission fragment damage in materials. Material scientists will be able to use the measured material parameters to validate computer simulation codes and extrapolate the response of the material in a nuclear reactor environment. Utilizing a new heavy-ion accelerator will provide the appropriate energies and intensities to study these effects with beam intensities which allow experiments to run over hours or days instead of years. The XMAT facility will use a CW heavy-ion accelerator capable of providing beams of any stable isotope with adjustable energy up to 1.2 MeV/u for U-238(50+) and 1.7 MeV for protons. This energy is crucial to the design since it well mimics fission fragments that provide the major portion of the damage in nuclear fuels. The energy also allows damage to be created far from the surface of the material allowing bulk radiation damage effects to be investigated. The XMAT ion linac includes an electron cyclotron resonance ion source, a normal-conducting radio-frequency quadrupole and four normal-conducting multi-gap quarter-wave resonators operating at 60.625 MHz. This paper presents the 3D multi-physics design and analysis of the accelerating structures and beam dynamics studies of the linac.

Heavy ion linear accelerator for radiation damage studies of materials.

Science.gov (United States)

Kutsaev, Sergey V; Mustapha, Brahim; Ostroumov, Peter N; Nolen, Jerry; Barcikowski, Albert; Pellin, Michael; Yacout, Abdellatif

2017-03-01

A new eXtreme MATerial (XMAT) research facility is being proposed at Argonne National Laboratory to enable rapid in situ mesoscale bulk analysis of ion radiation damage in advanced materials and nuclear fuels. This facility combines a new heavy-ion accelerator with the existing high-energy X-ray analysis capability of the Argonne Advanced Photon Source. The heavy-ion accelerator and target complex will enable experimenters to emulate the environment of a nuclear reactor making possible the study of fission fragment damage in materials. Material scientists will be able to use the measured material parameters to validate computer simulation codes and extrapolate the response of the material in a nuclear reactor environment. Utilizing a new heavy-ion accelerator will provide the appropriate energies and intensities to study these effects with beam intensities which allow experiments to run over hours or days instead of years. The XMAT facility will use a CW heavy-ion accelerator capable of providing beams of any stable isotope with adjustable energy up to 1.2 MeV/u for 238 U 50+ and 1.7 MeV for protons. This energy is crucial to the design since it well mimics fission fragments that provide the major portion of the damage in nuclear fuels. The energy also allows damage to be created far from the surface of the material allowing bulk radiation damage effects to be investigated. The XMAT ion linac includes an electron cyclotron resonance ion source, a normal-conducting radio-frequency quadrupole and four normal-conducting multi-gap quarter-wave resonators operating at 60.625 MHz. This paper presents the 3D multi-physics design and analysis of the accelerating structures and beam dynamics studies of the linac.

Structured thermal surface for radiative camouflage.

Science.gov (United States)

Li, Ying; Bai, Xue; Yang, Tianzhi; Luo, Hailu; Qiu, Cheng-Wei

2018-01-18

Thermal camouflage has been successful in the conductive regime, where thermal metamaterials embedded in a conductive system can manipulate heat conduction inside the bulk. Most reported approaches are background-dependent and not applicable to radiative heat emitted from the surface of the system. A coating with engineered emissivity is one option for radiative camouflage, but only when the background has uniform temperature. Here, we propose a strategy for radiative camouflage of external objects on a given background using a structured thermal surface. The device is non-invasive and restores arbitrary background temperature distributions on its top. For many practical candidates of the background material with similar emissivity as the device, the object can thereby be radiatively concealed without a priori knowledge of the host conductivity and temperature. We expect this strategy to meet the demands of anti-detection and thermal radiation manipulation in complex unknown environments and to inspire developments in phononic and photonic thermotronics.

Radiation monitoring by minicomputer

International Nuclear Information System (INIS)

Seamons, M.

1977-01-01

Radiation monitoring at the Los Alamos Scientific Laboratory (LASL) ranges from measuring the potential build-up of alpha particle radiation in the offices and laboratories of LASL to the detection of radiation leakage from nuclear tests at the Nevada Test Site (NTS). This paper describes PDP-11 based systems to accomplish both types of monitoring. In the first system, filter papers are collected from monitoring stations around LASL. One filter paper is placed under any of 128 photomultiplier (PM) tubes exposing it to alpha radiation. Alpha particle ''hits'' are recorded in a 64-word hardware FIFO, which interrupts and is read by the computer. The FIFO makes it possible to handle short aggregate alpha particle bursts of up to 10 6 hits/s in a computer that can only process 10 4 hits/s. In the second system, up to 100 current measuring radiation probes feed data from the site of the nuclear test(s) to the computer by microwave. The software system can support three tests simultaneously. Both systems offer a high degree of flexibility in configuring for a new test and in real-time control of such things as channel assignment, selective data retrieval, and output formatting

Achievement of radiative feedback control for long-pulse operation on EAST

Science.gov (United States)

Wu, K.; Yuan, Q. P.; Xiao, B. J.; Wang, L.; Duan, Y. M.; Chen, J. B.; Zheng, X. W.; Liu, X. J.; Zhang, B.; Xu, J. C.; Luo, Z. P.; Zang, Q.; Li, Y. Y.; Feng, W.; Wu, J. H.; Yang, Z. S.; Zhang, L.; Luo, G.-N.; Gong, X. Z.; Hu, L. Q.; Hu, J. S.; Li, J.

2018-05-01

The active feedback control of radiated power to prevent divertor target plates overheating during long-pulse operation has been developed and implemented on EAST. The radiation control algorithm, with impurity seeding via a supersonic molecular beam injection (SMBI) system, has shown great success in both reliability and stability. By seeding a sequence of short neon (Ne) impurity pulses with the SMBI from the outer mid-plane, the radiated power of the bulk plasma can be well controlled, and the duration of radiative control (feedforward and feedback) is 4.5 s during a discharge of 10 s. Reliable control of the total radiated power of bulk plasma has been successfully achieved in long-pulse upper single null (USN) discharges with a tungsten divertor. The achieved control range of {{f}rad} is 20%–30% in L-mode regimes and 18%–36% in H-mode regimes. The temperature of the divertor target plates was maintained at a low level during the radiative control phase. The peak particle flux on the divertor target was decreased by feedforward Ne injection in the L-mode discharges, while the Ne pulses from the SMBI had no influence on the peak particle flux because of the very small injecting volume. It is shown that although the radiated power increased, no serious reduction of plasma-stored energy or confinement was observed during the control phase. The success of the radiation control algorithm and current experiments in radiated power control represents a significant advance for steady-state divertor radiation and heat flux control on EAST for near-future long-pulse operation.

Computation of Aerodynamic Noise Radiated from Ducted Tail Rotor Using Boundary Element Method

Directory of Open Access Journals (Sweden)

Yunpeng Ma

2017-01-01

Full Text Available A detailed aerodynamic performance of a ducted tail rotor in hover has been numerically studied using CFD technique. The general governing equations of turbulent flow around ducted tail rotor are given and directly solved by using finite volume discretization and Runge-Kutta time integration. The calculations of the lift characteristics of the ducted tail rotor can be obtained. In order to predict the aerodynamic noise, a hybrid method combining computational aeroacoustic with boundary element method (BEM has been proposed. The computational steps include the following: firstly, the unsteady flow around rotor is calculated using the CFD method to get the noise source information; secondly, the radiate sound pressure is calculated using the acoustic analogy Curle equation in the frequency domain; lastly, the scattering effect of the duct wall on the propagation of the sound wave is presented using an acoustic thin-body BEM. The aerodynamic results and the calculated sound pressure levels are compared with the known technique for validation. The sound pressure directivity and scattering effect are shown to demonstrate the validity and applicability of the method.

ANALISIS KESELAMATAN TERMOHIDROLIK BULK SHIELDING REAKTOR KARTINI

Directory of Open Access Journals (Sweden)

Azizul Khakim

2015-10-01

Full Text Available ABSTRAK ANALISIS KESELAMATAN TERMOHIDROLIK BULK SHIELDING REAKTOR KARTINI. Bulk shielding merupakan fasilitas yang terintegrasi dengan reaktor Kartini yang berfungsi sebagai penyimpanan sementara bahan bakar bekas. Fasilitas ini merupakan fasilitas yang termasuk dalam struktur, sistem dan komponen (SSK yang penting bagi keselamatan. Salah satu fungsi keselamatan dari sistem penanganan dan penyimpanan bahan bakar adalah mencegah kecelakaan kekritisan yang tak terkendali dan membatasi naiknya temperatur bahan bakar. Analisis keselamatan paling kurang harus mencakup analisis keselamatan dari sisi neutronik dan termo hidrolik Bulk shielding. Analisis termo hidrolik ditujukan untuk memastikan perpindahan panas dan proses pendinginan bahan bakar bekas berjalan baik dan tidak terjadi akumulasi panas yang mengancam integritas bahan bakar. Code tervalidasi PARET/ANL digunakan untuk analisis pendinginan dengan mode konveksi alam. Hasil perhitungan menunjukkan bahwa mode pendinginan konvekasi alam cukup memadai dalam mendinginkan panas sisa tanpa mengakibatkan kenaikan temperatur bahan bakar yang signifikan. Kata kunci: Bulk shielding, bahan bakar bekas, konveksi alam, PARET.   ABSTRACT THERMAL HYDRAULIC SAFETY ANALYSIS OF BULK SHIELDING KARTINI REACTOR. Bulk shielding is an integrated facility to Kartini reactor which is used for temporary spent fuels storage. The facility is one of the structures, systems and components (SSCs important to safety. Among the safety functions of fuel handling and storage are to prevent any uncontrolable criticality accidents and to limit the fuel temperature increase. Safety analyses should, at least, cover neutronic and thermal hydraulic calculations of the bulk shielding. Thermal hydraulic analyses were intended to ensure that heat removal and the process of the spent fuels cooling takes place adequately and no heat accumulation that challenges the fuel integrity. Validated code, PARET/ANL was used for analysing the

Superductile bulk metallic glass

International Nuclear Information System (INIS)

Yao, K.F.; Ruan, F.; Yang, Y.Q.; Chen, N.

2006-01-01

Usually, monolithic bulk metallic glasses undergo inhomogeneous plastic deformation and exhibit poor ductility (<2%) at room temperature. We report a newly developed Pd-Si binary bulk metallic glass, which exhibits a uniform plastic deformation and a large plastic engineering strain of 82% and a plastic true strain of 170%, together with initial strain hardening, slight strain softening and final strain hardening characteristics. The uniform shear deformation and the ultrahigh plasticity are mainly attributed to strain hardening, which results from the nanoscale inhomogeneity due to liquid phase separation. The formed nanoscale inhomogeneity will hinder, deflect, and bifurcate the propagation of shear bands

Development of natural radiation model for evaluation of background radiation in radiation portal monitor

Energy Technology Data Exchange (ETDEWEB)

Kim, Jong Bum; Lee, Jin Hyung; Moon, Myung Kook [Radioisotope Research and Development Division, Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

2016-11-15

In ports and airports, radiation portal monitors (RPM) are deployed to detect illicit radioactive materials. Detected gamma rays in a RPM include background radiation and radiation from a freight. As a vehicle moves through the RPM, the vehicle causes the fluctuations in the natural background radiation signal, which ranges of up to 30%. The fluctuation increases the uncertainty of detection signal and can be a cause of RPM false alarm. Therefore, it is important to evaluate background radiation as well as radiation from a container. In this paper, a natural background radiation model was developed to evaluate RPM. To develop natural background radiation model, a Monte Carlo simulation was performed and compared with experimental measurements from a RPM for {sup 40}K, {sup 232}Th series, and {sup 235}U series, which are major sources of natural background radiation. For a natural radiation source, we considered a cylindrical soil volume with 300 m radius and 1 m depth, which was estimated as the maximum range affecting the RPM by MCNP6 simulation. The volume source model was converted to surface source by using MCNP SSW card for computational efficiency. The computational efficiency of the surface source model was improved to approximately 200 times better than that of the volume source model. The surface source model is composed of a hemisphere with 20 m radius in which the RPM and container are modelled. The natural radiation spectrum from the simulation was best fitted to the experimental measurement when portions of {sup 40}K, {sup 232}Th series, and {sup 235}U series were 0.75, 0.0636, and 0.0552 Bq·g{sup -1}, respectively. For gross counting results, the difference between simulation and experiment was around 5%. The background radiation model was used to evaluate background suppression from a 40 ft container with 7.2 m·s{sup -1} speed. In further study, background models and freight models for RPM in real container ports will be developed and applied to

Bulk viscosity of molecular fluids

Science.gov (United States)

Jaeger, Frederike; Matar, Omar K.; Müller, Erich A.

2018-05-01

The bulk viscosity of molecular models of gases and liquids is determined by molecular simulations as a combination of a dilute gas contribution, arising due to the relaxation of internal degrees of freedom, and a configurational contribution, due to the presence of intermolecular interactions. The dilute gas contribution is evaluated using experimental data for the relaxation times of vibrational and rotational degrees of freedom. The configurational part is calculated using Green-Kubo relations for the fluctuations of the pressure tensor obtained from equilibrium microcanonical molecular dynamics simulations. As a benchmark, the Lennard-Jones fluid is studied. Both atomistic and coarse-grained force fields for water, CO2, and n-decane are considered and tested for their accuracy, and where possible, compared to experimental data. The dilute gas contribution to the bulk viscosity is seen to be significant only in the cases when intramolecular relaxation times are in the μs range, and for low vibrational wave numbers (<1000 cm-1); This explains the abnormally high values of bulk viscosity reported for CO2. In all other cases studied, the dilute gas contribution is negligible and the configurational contribution dominates the overall behavior. In particular, the configurational term is responsible for the enhancement of the bulk viscosity near the critical point.

Analysis of a Lennard-Jones fcc structure melting to the corresponding frozen liquid: Differences between the bulk and the surface

International Nuclear Information System (INIS)

Olivi-Tran, N.; Faivre, A.

2009-01-01

We computed a Lennard-Jones frozen liquid with a free surface using classical molecular dynamics. The structure factor curves on the free surface of this sample were calculated for different depths knowing that we have periodic boundary conditions on the other parts of the sample. The resulting structure factor curves show an horizontal shift of their first peak depending on how deep in the sample the curves are computed. We analyze our resulting curves in the light of spatial correlation functions during melting. The conclusion is that the differences between bulk and surface are quite small during melting and that at the end of melting, only the very surface happens to be less dense than the bulk. This result is intrinsic to the shape of the Lennard-Jones potential and does not depend on any other parameter.

Automotive Underhood Thermal Management Analysis Using 3-D Coupled Thermal-Hydrodynamic Computer Models: Thermal Radiation Modeling

Energy Technology Data Exchange (ETDEWEB)

Pannala, S; D' Azevedo, E; Zacharia, T

2002-02-26

The goal of the radiation modeling effort was to develop and implement a radiation algorithm that is fast and accurate for the underhood environment. As part of this CRADA, a net-radiation model was chosen to simulate radiative heat transfer in an underhood of a car. The assumptions (diffuse-gray and uniform radiative properties in each element) reduce the problem tremendously and all the view factors for radiation thermal calculations can be calculated once and for all at the beginning of the simulation. The cost for online integration of heat exchanges due to radiation is found to be less than 15% of the baseline CHAD code and thus very manageable. The off-line view factor calculation is constructed to be very modular and has been completely integrated to read CHAD grid files and the output from this code can be read into the latest version of CHAD. Further integration has to be performed to accomplish the same with STAR-CD. The main outcome of this effort is to obtain a highly scalable and portable simulation capability to model view factors for underhood environment (for e.g. a view factor calculation which took 14 hours on a single processor only took 14 minutes on 64 processors). The code has also been validated using a simple test case where analytical solutions are available. This simulation capability gives underhood designers in the automotive companies the ability to account for thermal radiation - which usually is critical in the underhood environment and also turns out to be one of the most computationally expensive components of underhood simulations. This report starts off with the original work plan as elucidated in the proposal in section B. This is followed by Technical work plan to accomplish the goals of the project in section C. In section D, background to the current work is provided with references to the previous efforts this project leverages on. The results are discussed in section 1E. This report ends with conclusions and future scope of

FAMOUS, faster: using parallel computing techniques to accelerate the FAMOUS/HadCM3 climate model with a focus on the radiative transfer algorithm

Directory of Open Access Journals (Sweden)

P. Hanappe

2011-09-01

Full Text Available We have optimised the atmospheric radiation algorithm of the FAMOUS climate model on several hardware platforms. The optimisation involved translating the Fortran code to C and restructuring the algorithm around the computation of a single air column. Instead of the existing MPI-based domain decomposition, we used a task queue and a thread pool to schedule the computation of individual columns on the available processors. Finally, four air columns are packed together in a single data structure and computed simultaneously using Single Instruction Multiple Data operations.

The modified algorithm runs more than 50 times faster on the CELL's Synergistic Processing Element than on its main PowerPC processing element. On Intel-compatible processors, the new radiation code runs 4 times faster. On the tested graphics processor, using OpenCL, we find a speed-up of more than 2.5 times as compared to the original code on the main CPU. Because the radiation code takes more than 60 % of the total CPU time, FAMOUS executes more than twice as fast. Our version of the algorithm returns bit-wise identical results, which demonstrates the robustness of our approach. We estimate that this project required around two and a half man-years of work.

Application of computational models to estimate organ radiation dose in rainbow trout from uptake of molybdenum-99 with comparison to iodine-131

International Nuclear Information System (INIS)

Martinez, N.E.; Johnson, T.E.; Pinder, J.E.

2016-01-01

This study compares three anatomical phantoms for rainbow trout (Oncorhynchus mykiss) for the purpose of estimating organ radiation dose and dose rates from molybdenum-99 ( 99 Mo) uptake in the liver and GI tract. Model comparison and refinement is important to the process of determining accurate doses and dose rates to the whole body and the various organs. Accurate and consistent dosimetry is crucial to the determination of appropriate dose-effect relationships for use in environmental risk assessment. The computational phantoms considered are (1) a geometrically defined model employing anatomically relevant organ size and location, (2) voxel reconstruction of internal anatomy obtained from CT imaging, and (3) a new model utilizing NURBS surfaces to refine the model in (2). Dose Conversion Factors (DCFs) for whole body as well as selected organs of O. mykiss were computed using Monte Carlo modeling and combined with empirical models for predicting activity concentration to estimate dose rates and ultimately determine cumulative radiation dose (μGy) to selected organs after several half-lives of 99 Mo. The computational models provided similar results, especially for organs that were both the source and target of radiation (less than 30% difference between all models). Values in the empirical model as well as the 14 day cumulative organ doses determined from 99 Mo uptake are compared to similar models developed previously for 131 I. Finally, consideration is given to treating the GI tract as a solid organ compared to partitioning it into gut contents and GI wall, which resulted in an order of magnitude difference in estimated dose for most organs. - Highlights: • Existing computational models for the internal dosimetry of trout are applied to 99 Mo uptake. • Consideration is given to the effect of alternate source distribution in the gut. • A hybrid computational phantom is developed. • At 14 days post-release, 99 Mo and 131 I provide similar

Graphene-assisted near-field radiative heat transfer between corrugated polar materials

International Nuclear Information System (INIS)

Liu, X. L.; Zhang, Z. M.

2014-01-01

Graphene has attracted great attention in nanoelectronics, optics, and energy harvesting. Here, the near-field radiative heat transfer between graphene-covered corrugated silica is investigated based on the exact scattering theory. It is found that graphene can improve the radiative heat flux between silica gratings by more than one order of magnitude and alleviate the performance sensitivity to lateral shift. The underlying mechanism is mainly attributed to the improved photon tunneling of modes away from phonon resonances. Besides, coating with graphene leads to nonlocal radiative transfer that breaks Derjaguin's proximity approximation and enables corrugated silica to outperform bulk silica in near-field radiation.

46 CFR 148.04-23 - Unslaked lime in bulk.

Science.gov (United States)

2010-10-01

... 46 Shipping 5 2010-10-01 2010-10-01 false Unslaked lime in bulk. 148.04-23 Section 148.04-23... HAZARDOUS MATERIALS IN BULK Special Additional Requirements for Certain Material § 148.04-23 Unslaked lime in bulk. (a) Unslaked lime in bulk must be transported in unmanned, all steel, double-hulled barges...

The Intercomparison of 3D Radiation Codes (I3RC): Showcasing Mathematical and Computational Physics in a Critical Atmospheric Application

Science.gov (United States)

Davis, A. B.; Cahalan, R. F.

2001-05-01

The Intercomparison of 3D Radiation Codes (I3RC) is an on-going initiative involving an international group of over 30 researchers engaged in the numerical modeling of three-dimensional radiative transfer as applied to clouds. Because of their strong variability and extreme opacity, clouds are indeed a major source of uncertainty in the Earth's local radiation budget (at GCM grid scales). Also 3D effects (at satellite pixel scales) invalidate the standard plane-parallel assumption made in the routine of cloud-property remote sensing at NASA and NOAA. Accordingly, the test-cases used in I3RC are based on inputs and outputs which relate to cloud effects in atmospheric heating rates and in real-world remote sensing geometries. The main objectives of I3RC are to (1) enable participants to improve their models, (2) publish results as a community, (3) archive source code, and (4) educate. We will survey the status of I3RC and its plans for the near future with a special emphasis on the mathematical models and computational approaches. We will also describe some of the prime applications of I3RC's efforts in climate models, cloud-resolving models, and remote-sensing observations of clouds, or that of the surface in their presence. In all these application areas, computational efficiency is the main concern and not accuracy. One of I3RC's main goals is to document the performance of as wide a variety as possible of three-dimensional radiative transfer models for a small but representative number of ``cases.'' However, it is dominated by modelers working at the level of linear transport theory (i.e., they solve the radiative transfer equation) and an overwhelming majority of these participants use slow-but-robust Monte Carlo techniques. This means that only a small portion of the efficiency vs. accuracy vs. flexibility domain is currently populated by I3RC participants. To balance this natural clustering the present authors have organized a systematic outreach towards

Pressure effect of glass transition temperature in Zr46.8Ti8.2Cu7.5Ni10Be27.5 bulk metallic glass

DEFF Research Database (Denmark)

Jiang, Jianzhong; Roseker, W.; Sikorski, M.

2004-01-01

Pressure effects on glass transition temperature and supercooled liquid region of a Zr46.8Ti8.2Cu7.5Ni10Be27.5 bulk glass have been investigated by performing in situ high-temperature and high-pressure x-ray powder diffraction measurements using synchrotron radiation. The glass transition was det...... range of 0-2.2 GPa. This method opens a possibility to study the pressure effect of glass transition process in glassy systems under high pressures (>1 GPa). (C) 2004 American Institute of Physics.......Pressure effects on glass transition temperature and supercooled liquid region of a Zr46.8Ti8.2Cu7.5Ni10Be27.5 bulk glass have been investigated by performing in situ high-temperature and high-pressure x-ray powder diffraction measurements using synchrotron radiation. The glass transition...... was detected from the change of the slope of peak position as a function of temperature. It is found that the glass transition temperature increases with pressure by 4.4 K/GPa for the Zr46.8Ti8.2Cu7.5Ni10Be27.5 bulk glass, and the supercooled liquid range decreases with pressure by 2.9 K/GPa in a pressure...

Bulk solitary waves in elastic solids

Science.gov (United States)

Samsonov, A. M.; Dreiden, G. V.; Semenova, I. V.; Shvartz, A. G.

2015-10-01

A short and object oriented conspectus of bulk solitary wave theory, numerical simulations and real experiments in condensed matter is given. Upon a brief description of the soliton history and development we focus on bulk solitary waves of strain, also known as waves of density and, sometimes, as elastic and/or acoustic solitons. We consider the problem of nonlinear bulk wave generation and detection in basic structural elements, rods, plates and shells, that are exhaustively studied and widely used in physics and engineering. However, it is mostly valid for linear elasticity, whereas dynamic nonlinear theory of these elements is still far from being completed. In order to show how the nonlinear waves can be used in various applications, we studied the solitary elastic wave propagation along lengthy wave guides, and remarkably small attenuation of elastic solitons was proven in physical experiments. Both theory and generation for strain soliton in a shell, however, remained unsolved problems until recently, and we consider in more details the nonlinear bulk wave propagation in a shell. We studied an axially symmetric deformation of an infinite nonlinearly elastic cylindrical shell without torsion. The problem for bulk longitudinal waves is shown to be reducible to the one equation, if a relation between transversal displacement and the longitudinal strain is found. It is found that both the 1+1D and even the 1+2D problems for long travelling waves in nonlinear solids can be reduced to the Weierstrass equation for elliptic functions, which provide the solitary wave solutions as appropriate limits. We show that the accuracy in the boundary conditions on free lateral surfaces is of crucial importance for solution, derive the only equation for longitudinal nonlinear strain wave and show, that the equation has, amongst others, a bidirectional solitary wave solution, which lead us to successful physical experiments. We observed first the compression solitary wave in the

Module 13: Bulk Packaging Shipments by Highway

International Nuclear Information System (INIS)

Przybylski, J.L.

1994-07-01

The Hazardous Materials Modular Training Program provides participating United States Department of Energy (DOE) sites with a basic, yet comprehensive, hazardous materials transportation training program for use onsite. This program may be used to assist individual program entities to satisfy the general awareness, safety training, and function specific training requirements addressed in Code of Federal Regulation (CFR), Title 49, Part 172, Subpart H -- ''Training.'' Module 13 -- Bulk Packaging Shipments by Highway is a supplement to the Basic Hazardous Materials Workshop. Module 13 -- Bulk Packaging Shipments by Highway focuses on bulk shipments of hazardous materials by highway mode, which have additional or unique requirements beyond those addressed in the ten module core program. Attendance in this course of instruction should be limited to those individuals with work experience in transporting hazardous materials utilizing bulk packagings and who have completed the Basic Hazardous Materials Workshop or an equivalent. Participants will become familiar with the rules and regulations governing the transportation by highway of hazardous materials in bulk packagings and will demonstrate the application of these requirements through work projects and examination

27 CFR 20.191 - Bulk articles.

Science.gov (United States)

2010-04-01

... 27 Alcohol, Tobacco Products and Firearms 1 2010-04-01 2010-04-01 false Bulk articles. 20.191... Users of Specially Denatured Spirits Operations by Users § 20.191 Bulk articles. Users who convey articles in containers exceeding one gallon may provide the recipient with a photocopy of subpart G of this...

A local-area-network based radiation oncology microcomputer system

International Nuclear Information System (INIS)

Chu, W.K.; Taylor, T.K.; Kumar, P.P.; Imray, T.J.

1985-01-01

The application of computerized technology in the medical specialty of radiation oncology has gained wide acceptance in the past decade. Recognizing that most radiation oncology department personnel are familiar with computer operations and terminology, it appears reasonable to attempt to expand the computer's applications to other departmental activities, such as scheduling, record keeping, billing, treatment regimen and status, etc. Instead of sharing the processing capability available on the existent treatment minicomputer, the radiation oncology computer system is based upon a microcomputer local area network (LAN). The system was conceptualized in 1984 and completed in March 1985. This article outlines the LAN-based radiation oncology computer system

Radiation Effects in Paediatric radiography

International Nuclear Information System (INIS)

Mutwasi, O.

2006-01-01

Diagnostic imaging has evolved from single technique to a field which we have a choice from many modalities. Some without radiation. Radiation producing modalities include plain films (low dose), Fluoroscopy (mid range dose), Computed tomography (high dose). Radiography dose can significantly be influenced in plain radiography by varying speed of screens, cassette construction and type of radiography. E.g. digital or computed. In computed or digital radiography we are no longer able to tell h igh dose b y the quality of images. The final image is by great extend a product of post processing algorithms. It's for this reasons that the basic understanding of the sensitivity and specifying of various types of examinations and of specifically radiation effects is mandatory for a paediatric imager

Bulk metallic glass matrix composites

International Nuclear Information System (INIS)

Choi-Yim, H.; Johnson, W.L.

1997-01-01

Composites with a bulk metallic glass matrix were synthesized and characterized. This was made possible by the recent development of bulk metallic glasses that exhibit high resistance to crystallization in the undercooled liquid state. In this letter, experimental methods for processing metallic glass composites are introduced. Three different bulk metallic glass forming alloys were used as the matrix materials. Both ceramics and metals were introduced as reinforcement into the metallic glass. The metallic glass matrix remained amorphous after adding up to a 30 vol% fraction of particles or short wires. X-ray diffraction patterns of the composites show only peaks from the second phase particles superimposed on the broad diffuse maxima from the amorphous phase. Optical micrographs reveal uniformly distributed particles in the matrix. The glass transition of the amorphous matrix and the crystallization behavior of the composites were studied by calorimetric methods. copyright 1997 American Institute of Physics

Ionic polymerization of p-methoxystyrene and other styrene derivatives by radiation. [Gamma radiation

Energy Technology Data Exchange (ETDEWEB)

Hayashi, K; Pepper, D C [Trinity Coll., Dublin (Ireland)

1976-01-01

Polymerization of p-methoxystyrene by radiation was studied in bulk. Upon drying the monomer, the rate of polymerization, Rsub(p), became greater, changing its dose rate dependence from 0.5 to 1. The molecular weight distribution of the obtained polymers failed to give a bimodal curve; however, the peak molecular weight increased with higher Rsub(p). These kinetic features can be explained by a coexistence of radical and cationic mechanisms, as has been established in styrene, though there remain ambiguities about the effects of additives. Copolymerizations with styrene and 2-chloroethyl vinyl ether also showed a cationic nature for the reaction. A survey of possibilities of ionic polymerization by radiation was also carried out in ten ring-substituted styrene derivatives.

Radiation and medicine: introduction

International Nuclear Information System (INIS)

Lentle, B.; Singh, H.

1984-01-01

A brief historical review is given of the development of the various nuclear medicine techniques which have been evolved since the discovery of X-rays and radioactivity. The role of various disciplines, such as radiobiology, radiation chemistry, radiation physics and computers in the application of radiation in medicine is discussed. (U.K.)