最新刊期
卷 44 ， 期 6 ， 2021
- “上海光源X射线成像线站采用GPU并行计算，实现X射线动态显微CT快速重构，加速比达200倍。”摘要：BackgroundMassive projection data are produced by user experiments with the X-ray dynamic micro-computed tomography (CT) method on the X-ray imaging beamline at Shanghai synchrotron radiation facility (SSRF). CT reconstruction method based on central processing unit (CPU) serial computing is slow, which leads to a large backlog of experimental data. Graphics processing unit (GPU) is widely used in the field of high-performance computing because of its multi-core architecture and large-scale parallelization.PurposeThis study aims to speed up CT reconstruction by making use of GPU parallel computation for X-ray dynamic micro-CT on the X-ray imaging beamline at SSRF.MethodsAccording to computer unified device architecture (CUDA) programming standard, the back projection process of the filtered back projection (FBP) CT reconstruction algorithm was parallelized, and fast reconstruction of X-ray dynamic micro-CT was implemented on GPU of NVDIA RTX2080. CT reconstruction time was compared with that of CPU-based reconstruction method.ResultsThe comparison of CT reconstruction time shows that the CT reconstruction based on GPU parallel computing achieves about 200 times speedup compared with the CT reconstruction based on CPU serial computing, and the reconstruction time of a set of CT projection data is reduced from minutes to seconds.ConclusionsWith the powerful computing power of GPU, the fast reconstruction of X-ray dynamic micro-CT can be realized.关键词：X-ray dynamic micro-CT;GPU;Parallel computing;CT reconstruction;Fast X-ray imaging
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发布时间：2024-10-25 - “在甲烷氧化催化剂研究领域，科学家采用两步浸渍法制备了铋掺杂的铂基催化剂，并通过XAFS表征揭示了铋与铂之间的强相互作用，为双金属催化剂的制备提供了指导。”摘要：Background060102PurposeThis study aims to detect the interaction between platinum (Pt) and bismuth (Bi) species and their "structure-activity" relationship in methane oxidation through X-ray absorption fine structure (XAFS) technology.MethodsFirst of all, the CeZrLaOx support was prepared by hydrothermal method. Then, the platinum and bismuth species were deposited on the surface of CeZrLaOx support via two-step impregnation method with calcination temperature at 700 ºC. The structure-activity relationship of platinum- bismuth catalyst in methane oxidation was characterized by the X-ray diffraction (XRD), the X-ray photoelectron spectroscopy (XPS) and high angle annular dark field image-scanning transmission electron microscope (HAADF-STEM). Finally, the X-ray Absorption Fine Structure (XAFS) of samples was measured at BL14W1 beamline of Shanghai Synchrotron Radiation Facility (SSRF).ResultsExperimental results show that the dispersion of platinum through strong interaction between platinum and bismuth is enhanced by the doping of bismuth species as confirmed by XRD and hydrogen temperature program reduction (H2-TPR). However, results of XPS and HAADF-STEM indicate that overmuch Bi or BiOx species hinders the contact between platinum and methane molecule, hence leads to low activity.ConclusionsThe strong interaction between platinum and bismuth species confirmed by XAFS technique markedly enhances thermo-stability of catalysts and gives some guiding significance for the preparation of bimetallic catalysts.关键词：X-ray adsorption fine structure;Methane oxidation;Strong interaction;Platinum species;Bismuth species
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发布时间：2024-10-25 -
In-situ observation of reversible proton transport through Bi2Te3 anode of aqueous zinc-ion battery AI导读“在水系锌离子电池领域，科研人员采用一步水热法制备出碲化铋纳米结构材料，并首次将其应用于电池正极，通过同步辐射原位X射线衍射技术，实时观察到碲化铋纳米片反应过程中高度可逆的质子插层现象，证实了质子在碲化铋正极材料中的可逆输运特性。”摘要：backgroundThe rechargeable aqueous zinc-ion batteries have attracted increasing attention due to their low cost, high safety, non-toxicity and environmental protection.The exploitation of new anode materials with high specific capacity and working voltage is one of research hotspots of aqueous zinc-ion battery whilst bismuth telluride is such an emerging materials.PurposeThis study aims to observe the reversible proton transport in Bi2Te3 anode of aqueous zinc-ion battery.MethodFirst of all, bismuth telluride nanostructure was obtained by one-step hydrothermal exfoliating of bismuth telluride powder, and the bismuth telluride nanostructure was applied first time as anode material to aqueous zinc-ion battery. Then, both the scanning electron microscopy (SEM) and atomic force microscopy (AFM) were employed to oberve the nanosheets morphology and measure the thickness of synthesized Bi2Te3 nanosheets. Finally, in-situ synchrotron radiation X-ray diffraction (XRD) technique was used to track the changes of structure of Bi2Te3 nanosheets during the charge-discharge process of the battery.ResultThe thickness of synthesized Bi2Te3 nanosheets measured by AFM is about 3~5 nm, and a highly reversible proton intercalation disclosed by in-situ synchrotron radiation based XRD during the reaction process is responsible for the practical battery operation.ConclusionsThis study confirms the reversible transport properties of protons in bismuth telluride cathode materials.关键词：Aqueous zinc-ion battery;Bismuth telluride nanosheets;In-situ synchrotron radiation X-ray diffraction;Reversible proton intercalation- 371
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发布时间：2024-10-25
SYNCHROTRON RADIATION TECHNOLOGY AND APPLICATIONS
- “在自由电子激光领域，上海软X射线装置的高梯度C波段光阴极电子枪升级设计取得突破，显著改善了电子束发射度，满足FEL光源要求。”摘要：BackgroundFree electron laser (FEL) has extremely high requirements on emittance of the electron beam. In recent years, electron guns that can produce short electron bunches and have high brightness properties have become an important challenge and research hotspot for the development of high-performance FEL.PurposeThis study aims to increase the acceleration gradient in the RF electron gun by design and optimization of the C-band photocathode of the RF electron gun.MethodsBased on Shanghai XFEL facility, a new scheme was proposed to optimize the microwave field of electron gun, design the solenoid and set the initial beam distribution in terms of space charge effect. The effect of RF gradient in the RF gun on the beam dynamic was simulated. The principle of emittance compensation was analyzed in detail. The ASTRA code was used to optimize the current ratio of the solenoid's main and auxiliary coils from the engineering point of view, and the influence of the initial bunch distribution on the emittance was investigated. [ResultsandConclusions] The results show that by optimizing the number of electron gun cavities, the current ratio between the main and auxiliary solenoid coils of the solenoid and the initial bunch distribution, the emittance of the output bunch of the electron gun is significantly improved, satisfying the low emittance requirements of the FEL light source for the electron gun.关键词：Photocathode;RF gun;Emittance;Space charge force
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发布时间：2024-10-25 - “合肥先进光源项目预研中，研制新型非线性冲击磁铁，实际磁场满足设计要求。”摘要：BackgroundHefei advanced light facility (HALF) is a fourth-generation diffraction-limited storage ring (DLSR) in the range of the vacuum ultraviolet and soft X-ray region. Since 2017, HALF has been conducting pre-research and is considering off-axis injection scheme using nonlinear kicker.PurposeThis study aims to propose a new kind of nonlinear kicker for low emissivity storage ring to achieve beam injection into low emissivity storage ring.MethodsThe magnetic cores made of Mn-Zn ferrite was adopted as the structure of the kicker. The theoretical analysis of the magnetic field in the central region of the kicker was carried out by using OPERA2D/3D. The magnetic field patterns with different coating thicknesses were simulated. A complete prototype was produced and the magnetic field measurement was done.ResultsThe results show that the measured field in the center is about 3.6% of the peak filed strength, which is consistent well with the design requirements.ConclusionsThis work is of significance for beam injection of HALF.关键词：DLSR;Injection;Nonlinear kicker;Coating;Magnetic field measurement
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发布时间：2024-10-25 - “在快中子产额测量领域，4H-SiC探测器展现出优异性能，为相关研究提供新方案。实验获得探测器脉冲幅度谱，高能段反应特征峰清晰可辨，12C（n，α0）9Be特征峰的半峰全宽（Full Width at Half Maximum，FWHM）为190 keV，能量分辨率为2.26%，对快中子的注量响应εE=8.89×10^-6 n^-1·cm^-2（±7.7%）。”摘要：BackgroundFast neutron detectors based on 4H-SiC semiconductor materials have incomparable advantages over traditional neutron detectors when used in strong radiation and high temperature environments, such as fusion plasma diagnosis, core power monitoring, and neutron oil/gas logging, because they have large threshold displacement energy, wide band gap, and fast saturation speed.PurposeThis study aims to explore the feasibility of fast neutron yield measurement by using 4H-SiC detector.MethodsFirst of all, the main performance of 4H-SiC fast neutron detector was tested by experiments using the high intensity deuterium-tritium fusion neutron generator (HINEG). Then, the reaction characteristic peak of 12C(n,α0)9Be in the high energy section was observed in pulse amplitude spectrum. The full width at half maxima (FWHM) and energy resolution were calculated.ResultsThe experimental results show that the neutron detection efficiency to fast neutrons (εE) is 8.89×10-6 n-1·cm-2 (±7.7%),FWHM (full width at half maxima) of the characteristic peak of 12C(n,α0)9Be is 190 keV, and the energy resolution is 2.26%.ConclusionsThis study verifies that the 4H-SiC fast neutron detector can be used for neutron yield measurement.关键词：4H-SiC;Fast neutron yield measurement;Fluence response
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发布时间：2024-10-25
ACCELERATOR, RAY TECHNOLOGY AND APPLICATIONS
- “在量子干涉器件领域，专家基于RSJ模型建立了DC-SQUID阵列直流关系方程，为深入研究其低温特性提供理论基础。”摘要：BackgroundThe direct current superconducting quantum interference device (DC-SQUID) series array can be used as the second-stage amplifier of two stage DC-SQUID amplifier, or it can be used independently as readout device of Transition Edge Sensor (TES) detectors.PurposeThis study aims to establish a direct current relationship equation for exploring the DC characteristics of DC-SQUID series array.MethodsBased on the Josephson junction RSJ (Resistively Shunted Junction) mode, the direct current relationship equation was established. By solving the equivalent Foucault-Planck equation, the analytical expression under the influence of Gaussian white noise was obtained. Data on DC-SQUID series array were collected by high-precision electronics system, and experimental data were used to verify the accuracy of the equation.Results & ConclusionsThe DC circuit model and I-V relationship equation are established successfully. The influence of Gaussian white noise on the I-V curve is obtained. Experimental results show that the equations and models obtained in this paper are consistent with actual measurement results, and can be used for theoretical research.关键词：SQUID;Josephson junction;RSJ model;Gaussian white noise
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发布时间：2024-10-25 - “在铀资源勘查领域，专家通过蒙特卡罗模拟，研究井径与热中子俘获γ能谱的对应关系，为提高铀裂变瞬发中子测井的可靠性奠定基础。”摘要：BackgroundIn the exploration of uranium resources, the prompt fission neutron logging method saves the exploration cost and improves the detection efficiency with its advantage of directly measuring uranium. However, this method is greatly affected by the moderation and absorption of source neutrons by the formation environment, and must be corrected on site.PurposeThis study aims to reduce the impact on the caliper variation for prompt neutron well logging by making use of the capture γ spectrum.MethodsFirst of all, the corresponding relationship between caliper and thermal neutron capture γ spectroscopy was analyzed by Monte Carlo simulation based on the facts of 14 MeV deuterium-tritium (D-T) pulse neutron sources with a source distance of 30 cm for the uranium prompt fission neutron logging tube, two 3He gas detectors for neutron measurement, and one LaBr3(Ce) detector for γ spectrum acquisition. Well diameters of 110 mm, 130 mm and 160 mm were taken as simulation holes. Then, the variation of caliper was characterized by the hydrogen peak count rate of the captured γ spectrum, and the variation law of the hydrogen peak count rate was represented by a fitting function. Finally, the corresponding relationship between the hydrogen peak count rate and the caliper variation was obtained for the real-time correction of uranium mine caliper.ResultsSimulation results results shows that the change of well diameter can be characterized by the characteristic rate of hydrogen. The proposed method can reduce the influence of caliper change on the interpretation results of uranium fission prompt neutron logging.ConclusionsThis method has the ability to improve the reliability of uranium fission prompt neutron logging.关键词：Uranium logging;Prompt neutron;Caliper;Correction method
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发布时间：2024-10-25
NUCLEAR ELECTRONICS AND INSTRUMENTATION
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Simulation calculation of the migration and combination of interstitial atoms in nuclear graphite AI导读
“在核石墨研究领域，科学家利用第一性原理模拟揭示了间隙原子的相互作用、迁移和结合行为，为新石墨片层生成机制提供重要理论依据。”摘要：BackgroundThe interstitial atoms in nuclear graphite of the reactor will lead to the change of the properties and structure of the nuclear graphite. However, the migration and configuration of interstitial atoms in nuclear graphite are not well understood.PurposeThis study aims to clarify the migration and combination mechanism of interstitial atoms in nuclear graphite by First-principles calculation.MethodIn this research, the Vienna Ab-initio Simulation Package was used to calculate the properties of the system. First-principles calculation was used to study the interaction between interstitial atoms and the migration and combination behavior of interstitial atoms. The diffusion energy barrier was estimated by the climbing image nudge elastic band (CI-NEB) method.ResultsThere is a gravitational force between the interstitial atoms on the same graphite sheet, but it can be negligible while the distance between two interstitial atoms is greater than 0.5 nm. The interstitial atoms tend to migrate and combine along the armchair direction. The combination of two interstitial atoms reduces the structural energy by about 6.0 eV. The energy barrier of the entire migration and combination is about 0.4 eV during the migration process.ConclusionThe most stable cluster structure of interstitial atoms in graphite is the chain-like structure, and the secondary is the spiro structure of the closely adjacent interstitial atoms. When the number of interstitial atoms is more than 6, the structure of interstitial atoms exists as a cluster containing six-membered carbon rings and stacked with the bottom surface vertically into an AB configuration. If more interstitial atoms are combined, a new graphite sheet will eventually be formed.关键词：Nuclear graphite;Interstitial atoms;First-principles calculation;Migration and combination- 363
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发布时间：2024-10-25 - “高能物理实验研究中，海量数据获取处理面临挑战。研究者结合Hadoop框架，实现了流式数据获取框架BigDataDAQ，为处理海量数据提供解决方案。”摘要：BackgroundHigh energy physics (HEP) experiments aimed at studying elementary particles and their interactions need to acquire and analyze large amount of experimental data to discover new particles or measure the properties of known particles. With the development of HEP experiments, the energy and luminosity of accelerators are increasing, the scale of experiments is expanding, and consequently the acquisition, processing and analysis of large amount of data will be more challenging.PurposeThis study aims to design and implement a more advanced or effective distributed data acquisition framework to acquire and process the huge amount of data generated by tracking detectors for future HEP experiments where the number of channels and data volume of tracking detectors is extremely large.MethodsThe distributed data acquisition framework in HEP experiment divided into data flow software and online software was redesigned by using Hadoop big data framework, mainstream open source big data processing components was adopted to develope a new data acquisition framework—BigDataDAQ. Finally, this framework was applied to the prototype of the time projection chamber for verification.Results & ConclusionsResults of performance test show that the framework has high performance in data throughput and data processing, and can be easily deployed and managed. It provides a feasible solution for the future data acquisition system of high energy physics experiment.关键词：High energy physics experiment;Tracking detectors;Data acquisition system;Hadoop big data framework;Streaming data processing
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发布时间：2024-10-25
NUCLEAR PHYSICS, INTERDISCIPLINARY RESEARCH
- “在反应堆热工水力数值模拟领域，研究者利用前馈神经网络优化粗网格计算，显著提升了计算精度。”摘要：BackgroundThere is a prominent contradiction between calculation efficiency and calculation accuracy when computational fluid dynamics (CFD) program is used in the thermal-hydraulic numerical simulation of reactors.PurposeThis study aims to alleviate the contradiction to achieve higher calculation results with higher calculation efficiency by finding a method to effectively optimize the results of the coarse-grid numerical simulation.MethodsFirst of all, the feedforward neural network (FNN) machine learning (ML) method was employed to compare two sets of numerical simulation results under a certain number of similar working conditions under coarse and fine grids. Then, an error function expression with general applicability for similar conditions was obtained to optimize the numerical simulation calculation results of the coarse grid. Finally, the optimization effect was evaluated by comparing the root mean square error (RMSE) between the calculation results of relevant physical quantities before and after optimization and the calculation results under fine grid.ResultsThe research results show that after the coarse grid calculation result is optimized by the error function obtained by the FNN method, the RMSE of the physical quantity related to the fine grid is significantly reduced.ConclusionsThe coarse-grid numerical simulation optimization technology based on neural network established in this study can effectively improve the calculation accuracy of the reactor's coarse-grid numerical simulation, and provide a method reference for realizing high-precision numerical simulation with high computational efficiency.关键词：Neural network;Coarse grid;Numerical simulation;Optimization
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发布时间：2024-10-25 - “在熔盐堆低功率工况反应性引入事故研究中，专家分析了不同参数对事故后果的影响，为事故预防提供参考。”摘要：BackgroundIn the reactivity initiated accidents under low power operating conditions of molten salt reactor (MSR), different reactivity insertion rates will trigger different emergency shutdown signals. At the same time, the initial conditions such as the initial reactor power and the temperature coefficients of reactivity affect the accident process and cause differences in accident consequences.PurposeThe study aims to conduct a sensitivity analysis of the impact of the reactivity insertion rate, the initial reactor power, and the reactivity temperature coefficient on transient consequences.MethodsFirst of all, 7 reactivity insertion rate conditions were selected and simulated through RELAP5-TMSR.Then, 25 combinations of the initial reactor power and the temperature coefficients of reactivity were assumed as initial conditions. Finally, the effects of these three parameters on the consequences of the accident were discussed separately by using local sensitivity analysis method.ResultsThe insertion rate that causes a concurrent trigger of the high outlet temperature and the high-power shutdown signal leads to the most unfavorable consequence. The difference between the peak temperatures of the fuel salt and structural materials and their respective initial values under the worst reactivity insertion rate condition is negatively correlated with initial power. However, the temperature difference of each parameter caused by different initial power does not exceed 3 ℃. The difference between the peak temperatures decrease first and then increases with the increase of the temperature coefficients of reactivity, but the maximum difference does not exceed 0.5 ℃.ConclusionsUnder low power operating conditions of MSR, the consequences of reactivity introduced events are highly sensitive to the reactivity insertion rate and low sensitivity to the initial power and temperature coefficients of reactivity.关键词：Molten salt reactor;Low power;Reactive initiated accident;Sensitivity
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发布时间：2024-10-25 - “液态燃料熔盐堆安全分析取得新进展，基于一维缓发中子先驱核输运模型和二阶Godunov数值方法扩展了RELAP5/Mod4.0点堆模型，为液态燃料熔盐堆安全分析提供解决方案。”摘要：BackgroundThe liquid-fueled molten salt reactor (MSR) is one of the Generation IV advanced reactor concepts, which has unique advantages in aspects of safety, economy and nonproliferation. However, in view of the special neutron dynamics and hydrodynamics of the liquid-fueled MSR, traditional system analysis codes for solid fuel reactors cannot be applied to liquid-fueled MSR directly without improvement.PurposeThis study aims to improve the applicability and accuracy of the RELAP5/Mod4.0 code in liquid-fueled MSR simulation.MethodsFirst of all, the RELAP5/Mod4.0 code was expanded by adding a 1-D delayed neutron precursor (DNP) transport model to the code, hence the DNP concentration was calculated by an algorithm using a second-order Godunov method. The DNP model was coupled with built-in point kinetics model and hydrodynamics model. Then the code was validated by experimental data of the molten salt reactor experiment (MSRE) at Oak Ridge National Laboratory (ORNL), USA. Four transient scenarios studied in the MSRE were reproduced, including pump startup, pump coast down, natural-convection circulation and reactivity perturbation transients.ResultsThe results show that the numerical results are in good agreement with the experimental results, and the model with second-order Godunov method can simulate the delayed neutron precursor transport well.ConclusionsThe modified RELAP5/Mod4.0 code is suitable for liquid-fueled MSR transient and safety analysis. It provides a better and more powerful tool for design and optimization of the liquid-fueled MSR.关键词：MSR;1-D DNP;Transport model;Second-order Godunov
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发布时间：2024-10-25
NUCLEAR ENERGY SCIENCE AND ENGINEERING
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