A novel algorithm for frequency dependent modeling of ferrite ring and its optimum design to study VFTO behaviors within GIS

One of the fundamental issues in gas insulated substations (GIS) which has destructive effects on GIS equipment is the very fast transient over-voltages (VFTOs). This paper models a 400/230 kV substation in order to study the effects of VFTO extensively implemented on EMTP-RV. In addition, the application of ferrite rings for suppressing VFTOs is assessed thoroughly. The main advantage of this paper is its new proposed algorithm according to the ferrite ring frequency dependent modeling that is validated with experimental results. This paper examines the effects of three compositions of the ferrite ring on VFTO suppression. Moreover, it estimates the dimension of the ferrite ring based on the SF6 gas insulation withstand and the maximum effect of ferrite rings on VFTO suppression constraint with the COMSOL multiphysics software. Furthermore, it gains VFTO attenuated percentages due to the installation of the ferrite ring in different GIS nodes. Finally, it analyzes the offered VFTO amendment technique in various GIS switching scenarios.     

Numerical analysis and experimental validation of planar electrorefiner for spent nuclear fuel treatment using a tertiary model

To improve the uranium recovery rate in pyroprocessing, it is crucial to develop a planar-type electrorefiner. This can be achieved prior to actual experiments by using computer simulations to analyze the shape, arrangement, and size of the cathode. In this paper, tertiary-model-based computational analysis was performed on a planar-type electrorefiner. Flat-plate and rod-type cathodes were analyzed under constant-current condition; calculations were performed on high-efficiency-type electrodes with convection effects under the same conditions by comparing the dependence of the generated overpotential on the applied current. Analytic and experimental results were analyzed by comparing the electric potential of the plate-type device with that of a uranium electrorefiner while varying the arrangement of the electrodes.     

Simulation and experimental investigation of finishing forces in magnetic field assisted finishing process

Finishing forces in magnetic field assisted finishing process are normal force responsible for indentation and tangential force responsible for removal of indented materials. Analysis of finishing forces helps to understand the process mechanism and to control the process precisely. Simulation of finishing forces in magnetic field assisted finishing process is conducted using two finite element method based software packages. The experimental study confirms the simulation results as the difference between the obtained results from both the study is very small. A model is simulated for material removal using magnetorheological fluid having diamond abrasive particles on Ti alloy workpiece surface to predict material dislodgement during finishing. The significance of each process parameters is found out with the help of statistical analysis. The significant process parameters for normal force are abrasive volume concentration, working gap and carbonyl iron particle (CIP) volume concentration and for tangential force are tool rpm, working gap, and CIP volume concentration. It is perceived that the normal force rises with a surge in CIP concentration and reduction in abrasive concentration in MR fluid, working gap and tool rpm. The magnitude of tangential force rises with increased tool rpm, CIP concentration, abrasive concentration and decreased working gap.     

基于comsol软件的光子晶体通信器件模拟

利用comsol软件对几种光子晶体通信器件的模拟,有光子晶体光纤、波导、分波器以及滤波器等器件,模拟结果很好,可以更直观地了解光子晶体器件的优越性,更为开发集成光通信器件提供了有益的参考.     

矿石形状对浸堆结构及渗流场影响机制

为了研究筑堆矿石形状对堆内结构和渗流速度场分布的影响,选取了相同级配下的球团制粒矿石与普通原矿石进行柱浸实验。利用核磁共振成像(MRI)技术非接触地获取内部饱和结构,通过图像处理与统计研究了矿石形状与孔隙分布的关系,并利用Navier-Stokes方程模拟了相同压力和入渗速度下矿石形状对渗流速度场的与优势流分布影响。结果表明,饱和状态下的内部孔隙并不都服从正态分布,制粒矿石间孔隙分布更为均衡,服从正态分布,μ=2.0mm,原矿石间孔隙分布不服从正太分布,在8.00～11.00mm间缺失,最大当量直径为11.39mm;制粒矿石间速度场分布更加均匀,孔隙间无明显优势流,原矿石间速度场分布不均衡,存在贯穿结构的优势流和较大浸出盲区,出口边界表现为流场叠加状态;提出矿石形状均匀系数K可以有效描述矿石形状对内部孔隙和渗流的影响机制,K值小,孔隙分布均衡,渗流速度场分布均衡;K值大,容易产生大孔隙,连通成为优势流的通道,致使流场分布不均衡。     

采动扰动下充水断层安全与临界距离的流-固耦合分析

 应用Comsol有限元多物理场耦合软件,动态剖分模型采掘空间,以函数形式自定义流固耦合参数,模拟计算了巷道采掘扰动,充水断层水压力影响下围岩应力及变形的变化情况.算例显示:采掘扰动过程中,在充水断层与岩体的水压影响下,巷道距断层大于205m时,断层与煤层接触面应力和位移量基本为原始状态,距断层小于105m时,接触面压应力和向下位移量急剧增加,应力变化梯度明显增大,存在断层突水的可能.     

基于脉冲漏磁的带保温层管道腐蚀缺陷检测

在带保温层金属管道腐蚀检测方面,脉冲漏磁技术显示了潜在的优势.利用有限元分析软件Comsol Multiphysics对不同结构的传感器进行仿真分析的基础上,提出了一种优化结构的脉冲漏磁传感器,用于带保温层的管道腐蚀缺陷的检测.通过实验验证了传感器结构优化设计的有效性,为进一步量化分析缺陷信息打下基础.     

食品罐内壁涂层中双酚A-二缩水甘油醚双水合物的迁移特性的数值仿真与实验研究

对金属罐内壁涂层中的有害物质(双酚A-二缩水甘油醚双水合物,以下简称BADGE·2H2O)向食品模拟液在给定条件下的迁移特性进行了数值仿真,并与对应条件下的实验结果进行了对比、分析。结果表明:温度、初始浓度、涂层厚度对物质迁移的影响较大;对于给定的温度,温度越高,则迁移达到平衡时所需要的时间越短,迁移量越大;对于给定的初始浓度和涂层厚度,初始浓度越大,涂层厚度越厚,则迁移量越大;同时,在不同温度下,BADGE·2H2O从食品罐内壁涂层向水性模拟液迁移的数值解与实验值最大差值为0.023μg/mL。数值仿真与实验结果有较好的一致性。     

表面介质阻挡放电致动器的配置特性研究

沿面介质阻挡放电(SDBD)等离子体发生器在等离子体的产生中起着重要的作用.通过实验和仿真计算相结合的的方法,研究了大气压环境下等离子体发生器的结构对正弦波电源作用下放电的影响.结果表明:相同条件下,对称结构发生器电场强度最大,产生的等离子体分布在正面电极的两侧,等离子体层面积大,亮度高,但消耗功率较大;不对称结构发生器电场强度最低,产生的等离子体在正负电极处对称分布,整体看上去比较均匀;不对称结构底面电极封装之后正面电极处电场强度增强,等离子体分布在正面电极的一侧,亮度居中,底面电极附近的电场降低,抑制了低电极放电消耗能量,但均匀性最差.证明了等离子体激励器的封装抑制了底面电极的放电,同时降低了功耗.