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从老化筛选模型人手,阐述了老化模型参数热阻的重要性。基于热阻测量原理,给出了常见的热阻测量方法.同时分析了各测量方法的优缺点。在此基础上提出了一种新颖的封装热阻估计实验方法。虽然不能精确地测量出国产VLSI的热阻值.但给出了一种国产VLSI封装热阻数据的获取方法。实验证明其具有较强的实用性,不失为一种国产VLSI热阻参数快速确定的工程技术。 相似文献
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联锁系统是加速器装置的重要组成部分,用于保护设备和人员的安全。本文基于EPICS设计FELiChEM联锁系统,该系统由硬件联锁系统和软件联锁系统两部分组成,硬件联锁系统又分为机器保护系统(MPS)和人身安全保护系统(PPS)。硬件联锁系统的架构分为IOC层、Profinet IO控制层和Profinet IO设备层。每层均可进行冗余配置,而各层之间相互独立。原型样机的测试显示,硬件联锁系统的响应时间为2.144ms,远好于100ms的设计需求。软件联锁系统的设计采用联锁程序与配置文件分离的方式。测试表明,软件联锁逻辑完全由配置文件确定,具有非常好的灵活性。 相似文献
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在市场化大趋势的推动下,核电项目的成本管理意识空前强化。在众多成本管理的影响因素中,工程量是决定性因素。本文从概念区分的角度划分了核电项目实施过程的活动层次,进行了相应分析,找出了各个层次活动量的不同测量方式,通过对这些方式的本质解析和整合,既澄清了施工项目工程量概念本身,也澄清了一些模糊认识,为工程量的管理和成本管理的改进奠定了必要的基础。 相似文献
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高温气冷堆(简称高温堆)中,由于一回路冷却剂氦气中含有微量(ppm级)不纯杂质,其在高温环境中会对高温堆合金材料造成腐蚀,影响设备的性能。Inconel 617、Hastelloy X、Incoloy 800H是3种高温堆中间换热器及蒸汽发生器设备候选材料。研究表明,镍铬合金在高温下表面生成的富铬氧化层是防止合金在高温下发生严重腐蚀的重要因素。本文对3种合金在高温含杂质氦气中的腐蚀行为进行研究,探究预氧化对3种合金腐蚀行为的影响。并通过称重、扫描电镜、X射线能谱、电子探针显微分析仪以及碳硫分析仪对腐蚀结果进行分析。结果表明,3种合金均出现了不同的氧化和渗碳现象,预氧化对Hastelloy X合金抗腐蚀能力的提升不明显,对Inconel 617合金的抗氧化和渗碳能力有一定提升,对Incoloy 800H合金的抗渗碳腐蚀能力有一定提升。 相似文献
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《Journal of Nuclear Science and Technology》2013,50(5):371-376
Absorption rates of dilute iodine vapor contained in air by aqueous mixtures of sodium hydroxide and boric acid were measured using a laminar liquid jet column absorber at 298 K. Absorption rates in this system are controlled by a series of complex reactions taking place in the liquid phase. The reaction rate constant of iodine hydrolysis in the aqueous phase was determined from the absorption rates observed under the conditions that the base-catalytic hydrolysis reaction of iodine can be considered to be irreversible and that other reactions can be neglected. The absorption rates calculated theoretically with the rate constant value obtained above were in good accordance with the whole experimental data observed for a wide range of experimental conditions. 相似文献
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The dependence of radiation dose reduction on the sizes and materials of buildings was studied by numerical analyses using the Monte Carlo simulation code, PHITS. The dose rates inside the buildings were calculated by simulating gamma-ray transport from radioactive cesium deposited at the ground surface. Three building models were developed: the wooden house, the open-space concrete building, and the thin-wall building, to study the effect of building size and construction material on dose reduction inside these structures. Here the floor-area sizes of the building models were varied to clarify the influence of building configuration on dose reduction. The results demonstrated that the dose rates inside the buildings linearly decreased with increasing floor area on a logarithmic scale for all types of buildings considered. The calculated dose distribution inside a building indicated that the distance from the outer walls was a determining factor for the dose rate at each position in the building. The obtained tendency was verified by comparison with data reflecting the dose reduction of typical buildings in Japan. 相似文献
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中国实验快堆负荷跟踪能力分析 总被引:1,自引:1,他引:0
以中国实验快堆(CEFR)主工艺系统为对象,利用MATLAB/Simulink软件建立仿真模型。在负荷阶跃变化且无调节系统参与的条件下进行仿真计算,研究CEFR及类似工艺的池式钠冷快堆的负荷跟踪能力。分析关键环节在负荷阶跃变化的极端情况下的运行特性,探究此类工艺负荷跟踪运行模式的可行性,为未来大型快堆在运行模式和工艺设计上提供参考。仿真结果表明,CEFR及其类似工艺的池式钠冷快堆负荷跟踪能力有限,其中直流式蒸汽发生器是限制其负荷跟踪能力的最大瓶颈。 相似文献
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X射线板带材凸度检测系统采用双X射线源和双排充气电离室探测器,对热轧生产线上的钢板进行厚度和凸度等参数的检测,X射线的能量和强度是决定钢板测厚精度的重要因素。为了保证测量精度,本文依据国标GB/T15636—2008假定由统计涨落引入的测厚误差应小于±0.06%,在X光机管电压为180kV、电流为11mA的情况下,从理论上估算了满足以上精度探测器输出的最大相对标准偏差,通过实验对测厚范围内的钢板进行测量,计算出各路探测器输出在不同厚度钢板时的相对标准偏差。实验结果表明,在满足系统测量速度的情况下,通过对几个原始数据进行平均,可使统计涨落小于理论估算值。X光机设置的管电压和管电流参数满足测厚精度的要求。 相似文献
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本文采用计算流体动力学(CFD)方法针对直角梯形齿迷宫密封结构进行了三维数值模拟,对比研究间距对密封性能、流场分布、压力场分布、流速控制的影响,并在最佳间距尺寸下分析了偏心度对密封性能的影响。结果显示:扩大迷宫密封结构间距可有效减少漏流量、提高密封性能,并实现较好的流速控制,还可明显改善近壁面处的流动性能,强化对燃料组件外壁面的冷却;当间距超过3.02 mm时,密封性能提高有限,说明间距超过一定限值时,不能继续通过扩大间距提高迷宫密封结构密封性能,需在结构设计与工程应用中选择合理的间距尺寸;偏心现象导致迷宫密封结构流域内流速、压力分布不均匀,且随偏心度的增大不均匀现象有扩大的趋势,不仅对密封性能产生不利影响,还使得燃料组件振动加剧。 相似文献
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《Journal of Nuclear Science and Technology》2013,50(8):572-581
A fundamental equation for chromatography is derived starting from a very simple concept that the chromatographic movement of species can be expressed as the sum of the movement caused by the external force and the movement caused by the internal concentration gradient and its transformations into appropriate forms are discussed in the cases of ion exchange (or gas) chromatography and ionic migration, without or with a counterflow. By solving the fundamental equation, making appropriate assumptions, a comprehensive expression which describes the concentration profile is derived for two-isotope systems in any kind of chromatography. 相似文献
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辐射偏置条件是影响MOSFET(Metal Oxide Silicon Field Effect Transistor)总剂量辐射效应的主要因素之一,因为辐射时栅氧化层中电荷的产生、传输与俘获都与辐射偏置有关.本文采用10 keV X射线对MOSFET在不同频率的动态偏置条件下进行总剂量辐射,分析了MOSFET辐照前后的阈值电压的漂移量和辐射感生电荷对阈值电压的影响.实验结果表明,动态偏置频率越高,辐射对MOSFET电特性的影响越小,产生的辐射感生电荷越少. 相似文献
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小回旋加速器中若干电参数的研究 总被引:3,自引:3,他引:0
对小回旋加速器中的三角波电压线性度,最佳引出方位角,D盒安装公差等有关电参数进行了研究,为解决本项目实际工程中碰到的一系列具体问题提供了依据。 相似文献
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Dong-Hyun Kim Chang hwan Shin Hak-Sung Kim 《Journal of Nuclear Science and Technology》2018,55(10):1225-1234
A coated fuel cladding is one of the promising accident tolerant fuel (ATF) cladding concepts to enhance the fuel safety for accident conditions. In this study, a new analytical model called Fuel Rod and Cladding Analysis Subcode-Coated Cladding (FRACAS-CT), used to evaluate the mechanical behaviors of the ATF cladding, has been developed employing both thick-walled theory and some methodologies of the FRACAS. Based on the methodology of FRACAS, two different regimes of pellet-cladding mechanical interactions according to the gap status were considered as follows: one is an open-gap regime, and the other is a closed-gap regime. FRACAS-CT was developed within a limited scope of an elastic solution under the assumption of the prescribed creep, irradiation growth, and thermal deformation. To verify the FRACAS-CT model, an equivalent finite element (FE) model was proposed, and the mechanical behaviors of FRACAS-CT were compared with those of the equivalent FE model. As a result, it was determined that the stress results of FRACAS-CT are highly consistent with those of the equivalent FE model. Furthermore, FRACAS-CT was implemented into the FRAPCON4.0P1 code system to evaluate the mechanical behaviors of the ATF cladding using in-reactor conditions. 相似文献