- 标题
- 摘要
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- 实验方案
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Flux Region Assignment Method Using Ray Trace Information for the Method of Characteristics to Improve Cache Efficiency
摘要： A flux region assignment algorithm to increase cache efficiency for the method of characteristics (MOC) is proposed. In order to minimize the stride of memory access, flux region identifications are assigned based on the ray trace sequence during the MOC calculation. The present method is implemented in the three-dimensional transport code GENESIS and its performance is confirmed through verification calculations ranging from single pressurized water reactor (PWR) fuel assembly to PWR full-core benchmark problems. Quantitative comparison of cache efficiency is carried out and the present method shows improved cache efficiency, which results in a reduction in computation time. The present method can reduce computational time by improving cache efficiency while suppressing memory requirement.
关键词： GENESIS,flux region identifications,ray trace,Method of characteristics,cache
更新于2025-09-09 09:28:46
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Compact four-layer Timepix-based particle tracker WidePIX 3D: the first applications in X-ray CT imaging
摘要： WidePIX 3D is a compact Timepix-based particle tracking detector with 3D position sensitivity. The device consists of four Timepix chips with 300 μm silicon sensors tightly stacked together. The sensor volume is, therefore, divided into a 3D array of 256 × 256 × 4 voxels. Dual-energy X-ray imaging with sandwich detector is already known as single-shot dual-energy X-ray radiography utilizing a two-layer detector. In the case of WidePIX 3D, the detector can provide up to four sample images produced by di?erent photon spectra from a single exposure. Furthermore, the detection threshold of each layer can be individually adjusted to optimize the resolving performance for elements expected within the scanned sample. In this contribution we present the ?rst results of using the WidePIX 3D detector as an imaging camera for multi-channel energy-sensitive X-ray CT. The procedure of precise threshold-energy calibration of the detector using characteristic X-ray lines will be described and material-resolving CT data will be demonstrated.
关键词： Computerized Tomography (CT) and Computed Radiography (CR),Particle tracking detectors (Solid-state detectors),X-ray detectors
更新于2025-09-09 09:28:46
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Orientation dependence of electric field induced phase transitions in lead-free (Na <sub/>0.5</sub> Bi <sub/>0.5</sub> )TiO <sub/>3</sub> -based single crystals
摘要： The orientation dependence of the electric field induced strain and phase transitions in 0.92(Na0.5Bi0.5)TiO3-0.06BaTiO3-0.02(K0.5Na0.5)NbO3 (NBT-6BT-2KNN) single crystals has been investigated. The evolution of Raman spectra with electric field reveals that a tetragonal ferroelectric phase is initially induced at E=14kV/cm and completed above E=25kV/cm for [001] oriented single crystals. When the electric field is applied along [111] direction, a partial phase transition from pseudocubic to rhombohedral structure is triggered at E=19kV/cm, which is higher than that for inducing tetragonal ferroelectric phase along [001] direction. Both field-induced phase structures and stability of NBT-6BT-2KNN single crystal are strongly associated with the crystallographic orientations. These results provide a better understanding to the field-induced macroscopic strain in lead-free NBT-based ferroelectrics.
关键词： X-ray diffraction,lead-free ferroelectrics,electric field induced phase transitions,Raman spectroscopy,NBT-based single crystals
更新于2025-09-09 09:28:46
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FluxTracer - A Ray Tracer Post-Processor to Assist in the Design and Optimization of Solar Concentrators and Receivers
摘要： This paper presents FluxTracer, an advanced open source computer tools to assist in the analysis, design and optimization of solar concentrators and receivers. FluxTracer is a post-processor for Monte Carlo ray tracers used to simulate the optical behavior of solar concentrating systems. By post-processing the rays generated by the ray tracer, FluxTracer can partition into volumetric pixels (voxels) a region of interest in three-dimensional space defined by the user and compute for each voxel the radiant power density of the concentrated solar radiation. Depending upon the set of rays provided by the ray tracer, it may be able to integrate the radiant power density in every voxel over time. The radiant energy density analysis described is just one of the analysis that FluxTracer can carry out on the set of rays generated by the ray tracer. This article presents the main analyses that FluxTracer can provide. It also presents examples of how the information provided by FluxTracer can be used to assist in the analysis, design and optimization of solar concentrators and receivers. FluxTracer is the first of a series of components of an open-source computational framework for the analysis, design and optimization of solar concentrators and receiver, being developed by The Cyprus Institute (CYI) and the Australian National University (ANU).
关键词： receivers,FluxTracer,solar concentrators,Monte Carlo ray tracers,open source,optimization
更新于2025-09-09 09:28:46
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[ASME ASME 2018 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference - Quebec City, Quebec, Canada (Sunday 26 August 2018)] Volume 4: 23rd Design for Manufacturing and the Life Cycle Conference; 12th International Conference on Micro- and Nanosystems - New Insights Into Shape Memory Alloy Bimorph Actuators Formed by Electron Beam Evaporation
摘要： In order to create shape memory alloy (SMA) bimorph microactuators with high-precision features, a novel fabrication process combined with electron beam (E-beam) evaporation, lift-off resist and isotropic XeF2 dry etching method was developed. To examine the effect of E-beam deposition and annealing process on nitinol (NiTi) characteristics, the NiTi thin film samples with different deposition rate and overflow conditions during annealing process were investigated. With the characterizations using scanning electron microscope and x-ray diffraction, the results indicated that low E-beam deposition rate and argon employed annealing process could benefit the formation of NiTi crystalline structure. Besides, SMA bimorph microactuators with high-precision features as small as 5 microns were successfully the thermomechanical performance was experimentally verified and compared with finite element analysis simulation results.
关键词： microfabrication,annealing,microactuators,bimorph,lift-off resist,electron beam evaporation,XeF2 dry etching,NiTi,x-ray diffraction,shape memory alloy
更新于2025-09-09 09:28:46
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Comparative Analysis of Various Definitions of the Concept of Effective Atomic Number of Material of a Multicomponent Object
摘要： Comparative analysis is provided for various definitions of the concept of effective atomic number as applied to the material of a multicomponent object. Definitions in which radiation is and is not taken into account explicitly have been considered. Results of calculating the effective atomic numbers of various substances are presented on the basis of the definitions considered. New formal definitions are proposed for this concept when X-raying a multicomponent object with polychromatic radiation.
关键词： X-ray radiation,inspection checks,radiation mass attenuation coefficient,effective atomic number,multicomponent object
更新于2025-09-09 09:28:46
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Investigation of the Anisotropy of the Structural Properties of GaN(0001) Layers Grown by MOVPE on a-Plane (11$$\bar {2}$$0) Sapphire
摘要： The structural properties of GaN(0001) heteroepitaxial layers grown by metalorganic vapor phase epitaxy (MOVPE) on a-plane (11 0) sapphire substrates are investigated by X-ray diffractometry. Anisotropy of the rocking-curve width for the symmetric (0004) and asymmetric {11 4} and {10 5} reflections of gallium nitride upon rotation of the sample is observed. A comparison of the anisotropy of the rocking-curve width for GaN(0001)/Al2O3(11 0) layers with two different variants of in-plane orientation relationships suggests that the anisotropy of the structural properties is independent of the thermoelastic stress arising upon cooling the heterostructure.
关键词： structural properties,MOVPE,anisotropy,sapphire,GaN,X-ray diffractometry
更新于2025-09-09 09:28:46
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[ASME 2018 26th International Conference on Nuclear Engineering - London, England (Sunday 22 July 2018)] Volume 9: Student Paper Competition - Modelling of X-Ray Radioscopy for Phase Topology Estimation During Corium Sodium Interaction
摘要： In case of a severe accident scenario in a Sodium cooled Fast Reactor (SFR) such as the ASTRID demonstrator, the fuel might melt and interact with the coolant i.e. liquid sodium. This molten Fuel Coolant Interaction (FCI) can generate an energetic vapor explosion that can jeopardize the reactor structures. The yield of the vapor explosion is strongly dependent on the local distribution of the fragmented melt with respect to the local vapor fractions. The medium is composed of three phases, i.e. corium, liquid sodium and vapor sodium. Thus, a study of the three phase distribution within the system is a key to understand the extent of the explosion. PLINIUS-2, the future large mass experimental platform of CEA Cadarache will be dedicated to conducting experiments to understand the behavior of prototypic corium in case of severe accidents. In order to study these interactions, a high energy X-ray imaging system is being developed. This system consists of a 15 MeV Linear accelerator producing high energy X-rays with significantly high flux, which are attenuated as it passes through the highly dense test section. The transmitted radiation is detected and re-emitted as visible light by the GADOX screen coupled to the CMOS camera. Using this system to study the interaction between corium and sodium is particularly challenging due to the small corium particulates of the size of the order of 1 mm. The qualification of the foreseen radioscopy system on the visualization of such an interaction requires the development of physical phantoms. This paper presents the preliminary simulations of expected images of corium fragments in sodium, vapor bubbles and vapor film around the fragments. The simulations are carried out using a CEA Cadarache in-house tool MODHERATO, which produces radiographic images in satisfactory agreement with the real time imaging. The simulation of particles is based on the knowledge of interaction phenomenology gained from past experiments and on the statistical analysis of the size of corium particles formed. The models which, according to MODHERATO results, qualify to be detected and resolved, help manufacturing physical phantoms to conduct the experiments.
关键词： Sodium cooled Fast Reactor,Fuel Coolant Interaction,corium-sodium interaction,MODHERATO,X-ray imaging
更新于2025-09-09 09:28:46
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Archaeological applications of spectroscopic measurements. Compatibility of analytical methods in comparative measurements of historical Polish coins
摘要： The ED-XRF (energy-dispersive X-ray fluorescence) compact system was used to analyze selected Polish historical coins. The compact X-ray tube developed in the National Centre for Nuclear Research (NCBJ) was used as an X-ray source in the system designed for the ED-XRF studies. The XRF spectra were recorded with the Amptek SDD spectrometer. The elemental compositions of the coins have been determined using above mentioned system and the results were compared to those obtained with WD-XRF method. Other techniques such as SEM-EDX and XRD were also included into this work for comparison. The experimental data show that the X-ray system with transmission type X-ray tube with silver anode operating at 50 kV/30 mA which was developed in NCBJ together with the Amptek SDD spectrometer is an effective tool for chemical composition analyze of historical coins and can be successfully used in archaeometry.
关键词： Elemental composition,Energy-dispersive X-ray fluorescence,X-ray powder diffraction,Scanning electron microscope with Energy Dispersive X-Ray Spectroscopy,Wavelength-dispersive X-ray fluorescence
更新于2025-09-04 15:30:14
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Cherenkov light imaging in astroparticle physics
摘要： Cherenkov light induced by fast charged particles in transparent dielectric media such as air or water is exploited by a variety of experimental techniques to detect and measure extraterrestrial particles impinging on Earth. A selection of detection principles is discussed and corresponding experiments are presented together with breakthrough-results they achieved. Some future developments are highlighted.
关键词： cosmic-ray detectors,gamma-ray telescopes,Cherenkov detectors,neutrino telescopes,Astroparticle physics
更新于2025-09-04 15:30:14