Simulation and Modeling of Common Mode EMI Noise in Planar Transformers

The transformer is the key circuit component of the common-mode noise current when an isolated converter is working.The highfrequency characteristics of the transformer have an important influence on the common-mode noise of the converter.Traditionally,the measurement method is used for transformer modeling,and a single lumped device is used to establish the transformer model,which cannot be predicted in the transformer design stage.Based on the transformer common-mode noise transmission mechanism,this paper derives the transformer common-mode equivalent capacitance under ideal conditions.According to the principle of experimental measurement of the network analyzer,the electromagnetic field finite element simulation software three-dimensional(3D)modeling and simulation method is used to obtain the two-port parameters of the transformer,extract the high-frequency parameters of the transformer,and establish its electromagnetic compatibility equivalent circuit model.Finally,an experimental prototype is used to verify the correctness of the model by comparing the experimental measurement results with the simulation prediction results.

MOLECULAR MODELS AND FLOW CALCULATIONS Ⅱ.SIMULATION OF STEADY PLANAR FLOW

A multibead-rod model is used to replace the constitutive equation of continuum me- chanics in solving flow problems of steady-state planar flows of rigid-rodlike molecular suspensions.The governing equations then constitute a set of differential equations of the elliptic type,which is more ame- nable to numerical treatment than those of the mixed type.The conservation equations of the flow fields are solved by the boundary element method with linear boundary elements in physical space and the diffusion equation of the distribution function is solved separately by the Galerkin method in phase space. The solution to the flow problem is obtained when the convergence of the iteration procedure between the two spaces has been reached.Several numerical examples are shown and the interesting features of the present method are discussed in this paper.

One-dimensional Dynamic Modeling and Simulation of a Planar Direct Internal Reforming Solid Oxide Fuel Cell

This article aims to investigate the transient behavior of a planar direct internal reforming solid oxide fuel cell(DIR-SOFC) comprehensively.A one-dimensional dynamic model of a planar DIR-SOFC is first developed based on mass and energy balances,and electrochemical principles.Further,a solution strategy is presented to solve the model,and the International Energy Agency(IEA) benchmark test is used to validate the model.Then,through model-based simulations,the steady-state performance of a co-flow planar DIR-SOFC under specified initial operating conditions and its dynamic response to introduced operating parameter disturbances are studied.The dynamic responses of important SOFC variables,such as cell temperature,current density,and cell voltage are all investigated when the SOFC is subjected to the step-changes in various operating parameters including both the load current and the inlet fuel and air flow rates.The results indicate that the rapid dynamics of the current density and the cell voltage are mainly influenced by the gas composition,particularly the H2 molar fraction in anode gas channels,while their slow dynamics are both dominated by the SOLID(including the PEN and interconnects) temperature.As the load current increases,the SOLID temperature and the maximum SOLID temperature gradient both increase,and thereby,the cell breakdown is apt to occur because of excessive thermal stresses.Changing the inlet fuel flow rate might lead to the change in the anode gas composition and the consequent change in the current density distribution and cell voltage.The inlet air flow rate has a great impact on the cell temperature distribution along the cell,and thus,is a suitable manipulated variable to control the cell temperature.

Application of particle trajectory model in 1D planar ejection

A simple one-dimensional planar model for ejection was set up based on experiments.And numerical simulation was performed on this model with particle trajectory model method.An Eulerian finite volume method was conducted to resolve gas field.And Lagrangian method was imposed to track each particle.The interaction between gas and particles was responded as source terms in governing equations which were induced by forces.The effects of total spraying mass,particle size and other factors on the mixture of particles and gas were investigated.The spatial distributions of particle mass and velocity at different time were presented.The result shows that the numerical results are qualitatively consistent to those of experiments.

FURTHER RESEARCH ON THE SPLINE MODEL METHOD OF KED ANALYSIS IN A PLANAR FLEXIBLE LINKAGE

This paper relates to the deep research on the Splinc Model Method of KED analysis. With the use of cubic B-splinc function as a link’s transverse deflection interpolation function, the principle of virtual displacement is presented as a basic theory for the general formulation of the equations of motion, and thus abandoned the kinematic assumption and the instantaneous structure assumption which arc used in the Spline Model Method. In thc same time, the nonlinear terms sue as coupling terms between thc rigid body motion and elastic deformation arc included. New member’s spline models are established. Mass matrix, Coriolis mass matrix, normal and tangential mass matrix, linear stiffness matrix, nonlinear stiffness matrix and rotation matrix arc derived. The kinematic differential equations of a member and system are deduced in the end. The Newmark direct integration method is used as the solution scheme of the kinematic differential equations to get the periodic response.

A Method for Automatically Establishing a Mathematical Model of Kinematic Analysis to a Planar Mechanism with a Multiple Joint and Prismatic Pair

A method for automatically establishing a mathematical model of kinematic analysis to a planar mechanism with multiple joint and prismatic pair is presented. The breadth （ or depth ） first search spanning tree can be obtained based on an adjacency matrix of the mechanism. Then the kinematic chain （or mechanism）＇s basic loops can be obtained. On the basis of these basic loops, a mathematical model of kinematic analysis can be established and solved automatically. In the sense of a calculative mechanism, structural analysis of the kinematic chain relates to the kinematic analysis of a mechanism. Thus, an effective way is supplied to the given mechanism＇s kinematic analysis for automatic modeling and solving, and a method is supplied to the structural type to optimize kinematic synthesis.

Secure planar convex hull protocol for large-scaled point sets in semi-honest model

Efficiency and scalability are still the bottleneck for secure multi-party computation geometry(SMCG).In this work a secure planar convex hull(SPCH) protocol for large-scaled point sets in semi-honest model has been proposed efficiendy to solve the above problems.Firstly,a novel privacy-preserving point-inclusion(PPPI) protocol is designed based on the classic homomorphic encryption and secure cross product protocol,and it is demonstrated that the complexity of PPPI protocol is independent of the vertex size of the input convex hull.And then on the basis of the novel PPPI protocol,an effective SPCH protocol is presented.Analysis shows that this SPCH protocol has a good performance for large-scaled point sets compared with previous solutions.Moreover,analysis finds that the complexity of our SPCH protocol relies on the size of the points on the outermost layer of the input point sets only.

既有350 km/h铁路运行更高速铁路线路平面参数适应性分析

通过采用车线动力学分析方法,基于建立的动力学仿真模型,对某既有设计速度目标值为350 km/h的铁路曲线段进行了400 km/h运行的线路平面参数适应性研究。结果表明:(1)当列车速度提升至400 km/h后,多项动力学指标较350 km/h时增加较为明显,安全性与舒适性均有所下降;(2)尽管列车的安全性可以得到保障,但乘坐舒适度下降,存在一定的舒适度隐患,适应性有待进一步提高;(3)建议在可能的情况下,适当增大曲线半径与夹直线的长度,以保证旅客乘坐的安全性与舒适度。

基于二维平面水流数学模型的平原河道上跨改建桥梁流场影响分析

模型基于全方位不可压缩与雷诺数均匀分布的纳维斯托克斯方程,并服从于非线性布西尼斯克方程假定和静水压强的假定,通过对皖北平原河流上跨桥梁的河道二维水流数学模型研究,分析了平原河流在上跨桥梁改建后的流场变化,对比流速、流向变化,分析认为工程实施后,河道流速较小,减轻了洪水期现状河道的岸坡及主河槽的冲刷,受桥墩阻水作用影响,桥墩局部流场发生细微变化,但对河道流场的影响程度和影响范围较小,在较短河段内便可消除,工程对整个河道的流场影响较小。

Analytical expression of non steady-state concentration profiles at planar electrode for the CE mechanism

The analytical solutions of the non-steady-state concentrations of species at a planar microelectrode are presented. These simple new approximate expressions of concentrations are valid for all values of time and possible values of rate constants. Analytical equations are given to describe the current when the homogeneous equilibrium position lies heavily in favour of the electroinactive species. Working surfaces are presented for the variation of limiting current with a homogeneous kinetic parameter and equilibrium constant. Moreover, in this work we employ the Homotopy perturbation method to solve the boundary value problem.

An efficient method for tracing planar implicit curves

This paper presents a method for tracing a planar implicit curve f(x, y)=0 on a rectangular region based on continuation scheme. First, according to the starting track-point and the starting track-direction of the curve, make a new function F(x, y)=0 where the same curve with f(x, y)=0 is defined. Then we trace the curve between the two domains where F(x, y)>0 and F(x, y)<0 alternately, according to the two rules presented in this paper. Equal step size or adaptive step size can be used, when we trace the curve. An irregular planar implicit curve (such as the curve with large curvatures at some points on the curve), can be plotted if an adaptive step size is used. Moreover, this paper presents a scheme to search for the multiple points on the curve. Our method has the following advantages: (1) it can plot C0 planar implicit curves; (2) it can plot the planar implicit curves with multiple points; (3) by the help of using the two rules, our method does not need to compute the tangent vector at the points on the curve, and directly searches for the direction of the tracing curve; (4) the tracing procedure costs only one of two evaluations of function f(x, y)=0 per moving step, while most existing similar methods cost more evaluations of the function.

PROGRESSIVE FRACTURE MODELING OF THE FAILURE WAVE IN IMPACTED GLASS

The failure wave has been observed propagating in glass under impact loading since 1991. It is a continuous fracture zone which may be associated with the damage accumulation process during the propagation of shock waves. A progressive fracture model was proposed to describe the failure wave formation and propagation in shocked glass considering its heterogeneous meso-structures. The original and. nucleated microcracks will expand along the pores and other defects with concomitant dilation when shock loading is below the Hugoniot Elastic Limit. The governing equation of the failure wave is characterized by inelastic bulk strain with material damage and fracture. And the inelastic bulk strain consists of dilatant strain from nucleation and expansion of microcracks and condensed strain from the collapse of the original pores. Numerical simulation of the free surface velocity was performed and found in good agreement with planar impact experiments on K9 glass at China Academy of Engineering Physics. And the longitudinal, lateral and shear stress histories upon the arrival of the failure wave were predicted, which present the diminished shear strength and lost spall strength in the failed layer.

Ionospheric time delay corrections based on the extended single layer model over low latitude region

Ionospheric delay error is considered to be one of the most prominent factors impacting the Global Navigation Satellite Systems(GNSS) positioning and navigation accuracies. Due to dispersive nature and anisotropic of the ionosphere above certain regions, the positioning accuracy is seriously affected when using a precision-limited model. In this paper, an attempt has been taken to estimate ionosphere-delays based on Planar Fit(PF) and Spherical Harmonic Function(SHF) models by applying the commonly used single layer Model(SLM) and an extended single layer model(ESLM) which has been explored sparsely over the region. The results show that ESLM of PF and SHF techniques performed better in estimating ionospheric delay compared to the existing SLM model. Although the performance of the ESLM approach is almost comparable to the SLM results during the quiet ionospheric conditions, the ESLM-PF and ESLMSHF models led to respective improvements of 4.66% and 7.14% over the classically used SLM model under the disturbed ionospheric conditions. In view of the uneven variability of equatorial/low latitude ionosphere above the Indian subcontinental region, the suitability of ESLM-PF and ESLM-SHF models has been emphasized and suggested for assessing its completeness and reliableness across other parts of the globe. The output of this work may be useful for high precession GNSS positioning through mitigating the ionospheric delays under quiet as well as varied ionospheric conditions across the low/equatorial latitude regions.

Application of Planar Seismogenic Structure to the Seismotectonic Method——A Case Study in the Dayao-Yao'an Area

In seismic hazard analysis of nuclear power plant of China there is a need to identify both seismogenic structures and seismotectonic zones. In past practice,the identification of the seismogenic structures was often based on the surface active faults and characterization of linear seismic source. In a situation which shows quite strong non-random seismic activity and lacks surface active faults,it is difficult to evaluate the seismic hazard reasonably. Taking seismogenic structures in the Dayao-Yao'an area as a case study in this paper,we discuss the need and the possibility to apply the planar seismogenic structure to the seismotectonic method. We suggest that the planar seismogenic structure should be considered when applying the seismotectonic method to the seismic risk assessment of nuclear engineering in future.

基于在线差分进化算法的平面开关磁阻电机约束预测位置控制

模型预测控制方法在解决平面开关磁阻电机非线性、不确定干扰、约束等问题具有突出的优势,有望实现平面开关磁阻电机的高精度约束最优控制,目前平面开关磁阻电机约束预测控制亟需解决在线计算量大、内存大的问题。为快速、精确地求解平面开关磁阻电机约束预测控制在线优化问题,并获得小内存控制器,提出基于在线差分进化算法的约束预测位置控制方法。基于电机的多步预测位置模型,建立考虑输入约束的电机预测位置控制器,采用设计的差分进化算法在线求解最优控制量,构建具有摩擦补偿的电机约束预测位置控制系统。为提高差分进化算法的收敛速度并获得更优解,采用缩小种群范围、生成分区种群个体以及优化初始种群的操作产生初始种群,利用优化的变异因子和交叉因子对种群个体进行变异和交叉操作,将预测控制的代价函数作为适应度函数对种群个体进行选择操作。仿真和实验结果验证了所提方法的有效性。

平面变压器绕组损耗改进二维混合计算方法

高频下绕组损耗的快速计算方法对平面变压器精细化设计和优化有着至关重要的作用。对于垂直方向与水平方向同时存在交叉换位结构的平面变压器,其绕组损耗无法通过一维解析模型计算得到。为解决这一适用性问题,该文提出一种改进二维混合计算模型,从涡流场求解角度对绕组损耗进行计算。该模型将高度方向磁场强度考虑在内,在磁准静态假设以及二维假设基础上,以电流密度与磁场强度为变量对电磁场边值问题进行完全表述,并通过矩量法将电磁场边值问题转化为线性方程组求解问题。通过该文方法所建立线性方程组系数矩阵具有阶数较低,且不随剖分节点、单元数增加而增加的优点,达到确保一定计算精度的前提下有效节约计算成本的目标。搭建原副边匝数比为2:2的交叉结构平面变压器实验模型,对该文方法的有效性进行验证。

基于孔弹性效应的水平井多簇压裂诱导应力及裂缝扩展分析

页岩等非常规油气储层水平井分段压裂改造用液规模大,返排效率低,其诱发的孔弹性效应不可忽视,然而孔弹性效应对缝间应力干扰、多裂缝竞争扩展的影响机理尚未明晰。为了揭示压裂液滤失诱发的孔弹性效应对地应力场及多裂缝扩展的影响规律,基于平面三维多裂缝模型,在考虑液体滤失诱发的孔弹性效应的基础上,建立了水平井压裂裂缝扩展数学模型,并开展了水平井多簇压裂裂缝扩展数值模拟研究,针对孔弹性诱导应力导致多裂缝扩展不均匀提出了解决的工艺手段。研究结果表明:①孔弹性应力与裂缝诱导应力具有相似的效果,其大小约为裂缝诱导应力的30%,影响范围约为裂缝诱导应力的40%;②孔弹性效应会增大缝内压力、强化缝间应力干扰、加剧裂缝不均衡扩展,与不考虑孔弹性效应的模拟案例相比,考虑孔弹性效应后裂缝宽度降低约8%,缝内压力升高约0.5 MPa,井底压力升高0.62 MPa,各簇瞬时进液差异系数升高6.5%、整体进液差异系数升高5%;③保持限流射孔摩阻为3~6 MPa可在一定程度上克服孔弹性效应对各簇均衡进液的负面影响。结论认为,孔弹性效应研究可为水平井多簇压裂诱导应力及裂缝扩展分析提供重要的理论支撑和依据,该成果可为非常规油气储层现场压裂设计提供更加全面的参考依据。

基于ADAMS的平面四连杆机构运动学仿真分析

为了了解柔性部件对机械运动的影响,也为了在机械结构设计过程中减少设计误差,保证机械设计作品的可行性和有效性。基于ADAMS软件,创建平面四连杆机构虚拟模型,并对其进行运动学仿真分析。从影响机械运动的关键参数着手,即:仿真分析位移、速度、角速度、角加速度、各点作用力与力矩变化特性曲线,用特性曲线描述出平面四连杆的运动趋势,同时通过对比仿真数据与理论数据,得出其理论值与仿真值相差不大,表明利用ADAMS软件对平面四连杆机构进行仿真分析可以验证平面四连杆机构的运动可行性。这对于解决机械结构设计过程中出现的机械机构不合理、不可行等问题具有重要的作用,同时也在一定程度上了解了各部件在运动过程中的瞬时状态,增强对机械结构的分析能力,提高了设计效率。