Subdomain Model for Predicting Armature Reaction Field of Dual-Stator Consequent-Pole PM Machines Accounting for Tooth-Tips

This paper presents an exact analytical subdomain model of dual-stator consequent-pole permanent-magnet(DSCPPM)machines accounting for tooth-tips,which can accurately predict the armature reaction field distribution in DSCPPM machines.In the proposed subdomain model,the field domain is composed of four types of sub-regions,viz.magnets,outer/inner air gaps,slots and slot openings.The analytical expressions of vector potential in each sub-region are determined by boundary and interface conditions.In comparison to the analytically predicted results,the corresponding flux density field distributions computed by finite element(FE)method are analyzed,which confirms the excellent accuracy of the developed subdomain model.

Electromagnetic Performance Prediction for the Symmetrical Dual Three-phase Surface-mounted PMSM under Open-phase Faults Based on Accurate Subdomain Model

The paper presents an accurate analytical subdomain model for predicting the electromagnetic performance in the symmetrical dual three-phase surface-mounted permanent magnet synchronous machine(PMSM)under open-phase faulty conditions.The model derivations are extended from previous accurate subdomain models accounting for slotting effects.Compared with most conventional subdomain models for traditional three-phase machines with nonoverlapping winding arrangement,the subdomain model proposed in this paper applied for the 24-slot/4-pole dual three-phase machine with symmetrical overlapping winding arrangement.In order to investigate the postfault electromagnetic performance,the reconfigured phase currents and then current density distribution in stator slots under different open-circuit conditions are discussed.According to the developed model and postfault current density distribution,the steady-state electromagnetic performance,such as the electromagnetic torque and unbalanced magnetic force,under open-circuit faulty conditions are obtained.For validation purposes,finite element analysis(FEA)is employed to validate the analytical results.The result indicate that the postfault electromagnet performance can be accurately predicted by the proposed subdomain model,which is in good agreement with FEA results.

Time-Spectral Solution of Initial-Value Problems—Subdomain Approach

Temporal and spatial subdomain techniques are proposed for a time-spectral method for solution of initial-value problems. The spectral method, called the generalised weighted residual method (GWRM), is a generalisation of weighted residual methods to the time and parameter domains [1]. A semi-analytical Chebyshev polynomial ansatz is employed, and the problem reduces to determine the coefficients of the ansatz from linear or nonlinear algebraic systems of equations. In order to avoid large memory storage and computational cost, it is preferable to subdivide the temporal and spatial domains into subdomains. Methods and examples of this article demonstrate how this can be achieved.

Uniform Hölder Bounds for Competition Systems with Strong Interaction on a Subdomain

We prove the uniform Hölder bounds of solutions to a singularly perturbed elliptic system arising in competing models in population dynamics. In this system, two species compete to some extent throughout the whole domain but compete strongly on a subdomain. The proof relies upon the blow up technique and the monotonicity formula by Alt, Caffarelli and Friedman.

ON ALGEBROID FUNCTIONS IN A SUBDOMAIN OF THE COMPLEX PLANE

This paper discusses some basic properties of algebroid functions in a subdomain of the complex plane and some similar results (to those in the whole complex plane) and a new situation are showed.

An adaptive scaled boundary finite element method by subdividing subdomains for elastodynamic problems

The scaled boundary finite element method(SBFEM) is a semi-analytical numerical method,which models an analysis domain by a small number of large-sized subdomains and discretises subdomain boundaries only.In a subdomain,all fields of state variables including displacement,stress,velocity and acceleration are semi-analytical,and the kinetic energy,strain energy and energy error are all integrated semi-analytically.These advantages are taken in this study to develop a posteriori h-hierarchical adaptive SBFEM for transient elastodynamic problems using a mesh refinement procedure which subdivides subdomains.Because only a small number of subdomains are subdivided,mesh refinement is very simple and efficient,and mesh mapping to transfer state variables from an old mesh to a new one is also very simple but accurate.Two 2D examples with stress wave propagation were modelled.The results show that the developed method is capable of capturing propagation of steep stress regions and calculating accurate dynamic responses,using only a fraction of degrees of freedom required by adaptive finite element method.

Role of autoantibodies against the linker subdomains of envoplakin and periplakin in the pathogenesis of paraneoplastic pemphigus

Background The presence of autoantibodies against multiple epidermal proteins is an important feature in paraneoplastic pemphigus （PNP）. Circulating anti-desmoglein 3 autoantibody, the major pathogenic autoantibody in pemphigus vulgaris （PV）, has been proved pathogenic in PNP. Because of many clinical differences between PNP and PV, we speculate about the involvement of other autoantibodies in the pathogenesis of PNP. Envoplakin （EPL） and periplakin （PPL） are recognized by most PNP sera. Their linker subdomains are highly homologous and necessary for the association of intermediate filaments. Methods We characterized the autoantibodies against the linker subdomains of EPL and PPL in PNP patients＇ sera and their associated tumors by enzyme-linked immunosorbent assay （ELISA） and immunofluorence. We also applied the purified autoantibodies against EPL and PPL from PNP sera to cultured human epidermal keratinocytes （HEK）, to evaluate the changes of cell-cell adhesion. Results Autoantibodies against EPL and PPL were detected in most PNP patients by ELISA, and the decrease of these autoantibodies after removal of the tumors was roughly comparable to the improvement of clinical symptoms. Cultured tumor cells from PNP patients secreted these autoantibodies. Specific immunoglobulin receptors for EPL and PPL were found on B lymphocytes in tumors from PNP. Furthermore, purified anti-EPL and anti-PPL autoantibodies from PNP sera were capable of dissociating cultured human epidermal keratinocytes. Conclusion Autoantibodies against EPL and PPL may also be pathogenic in PNP.

RAPID EXACT CONTROLLABILITY OF THE WAVE EQUATION BY CONTROLS DISTRIBUTED ON A TIME-VARIANT SUBDOMAIN

Consider the wave equation with distributed controls supported on a subdomain, calledcontrol subdomain, which is allowed to be variant in time. For any prescribed time duration,the authors work out a scheme for changing the control subdomain such that the wave equationis exactly controllable on this time duration, where the control subdomain at any time is allowedto have arbitrarily small measure and relatively simple shape.

SPLITTING A CONCAVE DOMAIN TO CONVEX SUBDOMAINS

We will study the convergence property of Schwarz alternating method for concave region where the concave region is decomposed into convex subdomains. Optimality of regular preconditioner deduced from Schwarz alternating is also proved.It is shown that the convergent rate and the condition number are independent of the mesh size but dependent on the relative geometric position of subdomains.Special care is devoted to non-uniform meshes, exclusively, local properties like the shape regularity of the finite elements are utilized.

Adaptive subdomain integration method for representing complex localized geometry in ANCF

In this work,we propose incorporating the finite cell method(FCM)into the absolute nodal coordinate formulation(ANCF)to improve the efficiency and robustness of ANCF elements in simulating structures with complex local features.In addition,an adaptive subdomain integration method based on a triangulation technique is devised to avoid excessive subdivisions,largely reducing the computational cost.Numerical examples demonstrate the effectiveness of the proposed method in large deformation,large rotation and dynamics simulation.

An Efficient Particle Subdomain Quadrature Scheme for the Material Point Method

The material point method(MPM)has been proved to be an effective numerical method for large deformation problems.However,the MPM suffers from the cell crossing error as that the material particles are used to represent the deformed material and to perform the particle quadrature.In this paper,an efficient subdomain quadrature material point method(sqMPM)is proposed to eliminate the cell crossing error efficiently.The particle domain is approximated to be the line segment,rectangle,and cuboid for the one-,two-,and three-dimensional problems,respectively,which are divided into several different subdomains based on the topological relationship between the particle domain and background grid.A single Gauss quadrature point is placed at the center of each subdomain and used for the information mapping.The material quantities of each Gauss quadrature point are determined by the corresponding material particle and the subdomain volume without the cumbersome reconstruction algorithm.Numerical examples for one-,two-,and three-dimensional large deformation problems demonstrate the effectiveness and highly enhanced convergence and efficiency of the proposed sqMPM.

双层复合护套高速永磁电机转子涡流损耗解析模型

在表贴式高速永磁电机中,双层复合护套可以有效抑制转子涡流损耗。目前,针对双层复合护套转子涡流损耗的研究主要采用有限元法,但该方法存在耗时、对薄护套网格剖分较困难等问题,因此该文基于精确子域法提出了一种考虑定子开槽、涡流反作用的双层复合护套高速永磁电机转子涡流损耗通用解析模型。该模型同时考虑了永磁磁场励磁和电枢磁场励磁,可以计算负载磁场作用下的双层复合护套转子涡流损耗。此外,该模型还可进一步拓展至多层复合护套转子涡流损耗计算。通过该解析模型研究了双层复合护套不同护套厚度配比、不同护套材料对转子涡流损耗的影响。最后,将解析计算结果与有限元及C型铁心实验结果进行对比,验证了该解析模型的有效性。

双层永磁体结构高速永磁电机转子涡流损耗解析模型

对于采用低电导率护套高电导率永磁体的表贴式高速永磁电机,在永磁体和保护套之间增加一层低电导率的永磁体,可有效降低永磁体上的涡流损耗。目前,对于双层永磁体转子结构的电机在使用有限元软件进行转子涡流损耗计算时,因为需要寻求两种永磁体不同厚度配比下的最优方案,所以要进行大量参数化,导致计算时间长、效率低。针对这一问题,该文基于精确子域法,建立了一个考虑定子开槽以及涡流反作用影响的双层永磁体结构转子涡流损耗解析模型,可同时对电枢磁场和负载磁场下双层永磁体结构转子涡流损耗进行求解,并且该模型可扩展至多层永磁体复合结构的转子涡流损耗计算。在此基础上分析了双层永磁体结构下外层永磁体不同厚度和不同材料对转子涡流损耗和内层永磁体消耗量的影响。最后通过有限元仿真和C型铁心实验验证了该解析模型的有效性。

Dynamic Response of A Group of Cylindrical Storage Tanks with Baffles Considering the Effect of Soil Foundation

The sloshing in a group of rigid cylindrical tanks with baffles and on soil foundation under horizontal excitation is studied analytically.The solutions for the velocity potential are derived out by the liquid subdomain method.Equivalent models with mass-spring oscillators are established to replace continuous fluid.Combined with the least square technique,Chebyshev polynomials are employed to fit horizontal,rocking and horizontal-rocking coupling impedances of soil,respectively.A lumped parameter model for impedance is presented to describe the effects of soil on tank structures.A mechanical model for the soil-foundation-tank-liquid-baffle system with small amount of calculation and high accuracy is proposed using the substructure technique.The analytical solutions are in comparison with data from reported literature and numerical codes to validate the effectiveness and correctness of the model.Detailed dynamic properties and seismic responses of the soil-tank system are given for the baffle number,size and location as well as soil parameter.

Analytical Model and Topology Optimization of Doubly-fed Induction Generator

As the core component of energy conversion for large wind turbines,the output performance of doubly-fed induction generators (DFIGs) plays a decisive role in the power quality of wind turbines.To realize the fast and accurate design optimization of DFIGs,this paper proposes a novel hybriddriven surrogate-assisted optimization method.It firstly establishes an accurate subdomain model of DFIGs to analytically predict performance indexes.Furthermore,taking the inexpensive analytical dataset produced by the subdomain model as the source domain and the expensive finite element analysis dataset as the target domain,a high-precision surrogate model is trained in a transfer learning way and used for the subsequent multi-objective optimization process.Based on this model,taking the total harmonic distortion of electromotive force,cogging torque,and iron loss as objectives,and the slot and inner/outer diameters as parameters for optimizing the topology,achieve a rapid and accurate electromagnetic design for DFIGs.Finally,experiments are carried out on a 3MW DFIG to validate the effectiveness of the proposed method.

深度子领域自适应网络电机滚动轴承跨工况故障诊断

针对实际生产中旋转机械工况变化引起状态监测数据分布差异及获取待诊断样本标签困难问题,提出多尺度子领域自适应模型(MSDAM)的跨工况下滚动轴承故障诊断方法。首先,以原始振动信号作为输入,无需信号预处理及人工特征参数提取;其次,搭建多尺度卷积神经网络将已知标签样本和待诊断样本特征迁移到同一子空间,捕获具有细粒度信息的多尺度公共特征;然后,以不同的故障类型来划分相关子域,并通过局部最大均值距离(LMMD)来完成子域的适配,有效削弱不同工况同类故障特征的分布差异;最后,在三个数据集的多个迁移任务上进行试验验证。结果证明,所提MSDAM的跨工况故障诊断性能优于关注全局领域适配的迁移学习方法。

基于深度条件子域自适应网络的轴承跨域故障诊断研究

针对无监督跨域故障诊断领域存在标注数据不足、模型诊断精度低等问题,提出了一种新型深度条件子域自适应网络(DCSAN)。该网络将分类器预测的置信度映射到共享特征提取器所提取的特征中,以获得多模态映射特征,之后利用多核局部最大平均差异(MK-LMMD)度量不同域间多模态映射特征之间的距离。然后,通过最小化MK-LMMD和分类器损失函数,实现了源域和目标域相应子域分布的对齐。最后,在江南大学轴承数据集上对所提方法的可行性进行了验证。结果表明:在6个变工况迁移任务中,DCSAN模型的平均诊断准确率分别比深度适配网络(DAN)、域相关性对齐方法(D-CORAL)和基于对抗学习域适应方法(DANN)模型高出9.5百分点、8.0百分点和13.6百分点;所提DCSAN模型在子域对齐和跨域自适应故障诊断方面具有一定的有效性和优越性。

融入几何先验的圆柱表面三维应变场双目视觉测量方法

针对现有基于双目视觉的圆柱表面三维应变场测量方法从位移场计算应变场效率低下的问题,将圆柱结构几何先验信息融入子域投影法理论,利用圆柱标准坐标变换替代大量冗余的局部切平面最小二乘拟合求解,提出了一种融合圆柱拟合和子域投影的表面三维应变场计算方法;然后采用数值模拟方式,在不同应变区域和位移场噪声条件下,将所提方法与一般曲面子域投影法进行对比分析;最后开展圆柱拉伸实验,分别从单点和全场两个角度将所提方法的应变计算结果与应变片测量结果进行了对比。研究结果表明:在保证计算精度和位移场噪声鲁棒性的同时,所提方法将计算效率提高了约20%,且与应变片实验测量结果吻合较好,验证了该方法能够实现圆柱结构表面三维应变场的高效测量,也为规则结构表面三维应变场的计算提供了新思路。

卷积神经网络结合子域适应的低采样率肌电手势识别

为了提升模型识别低采样率肌电手势的性能,提出新的识别方法.通过信息扩展层对预处理后的低采样率肌电信号信息进行扩展,增强关键特征的表示.在特征提取网络中,利用子域适应网络提取源域与目标域中的域不变特征后进行域不变特征分类.使用NinaPro数据库中的DB1和DB5子数据库对所提方法进行评估.实验结果表明,所提方法识别53种和52种手势的最高准确率分别为90.89%(DB1)、89.90%(DB5)和82.01%(DB1)、77.07%(DB5),能够降低电极移位、肌肉疲劳、皮肤阻抗的变化和肌肉相对电极的相对运动等因素对低采样率肌电手势识别的影响.

混合励磁式电涡流制退机电磁场与阻力特性分析

电涡流制退机具有无液体泄漏、无需密封、阻力稳定的优势。与目前应用较多的永磁式电涡流制退机相比,混合励磁式电涡流制退机采用线圈替代了一部分永磁体,对阻力特性的调节效果更好。对比了混合励磁式电涡流制退机2种可能的结构形式,然后根据磁路分析与初步计算选择出具有更好阻力性能的结构。针对该结构,利用等效磁路法计算气隙磁场,采用子域模型考虑感生涡流影响,建立了求解混合励磁式电涡流制退机阻力值的等效子域模型。根据某口径火炮反后坐要求,确定了制退机的主要尺寸参数,完成了混合励磁式电涡流制退机结构参数的前期设计,并通过数值计算对解析计算结果进行了验证。接着,针对某口径火炮发射时的工况建立仿真模型,以炮膛合力曲线和复进机力的后坐行程函数曲线作为条件输入,分析强冲击载荷下混合励磁式电涡流制退机的电磁阻尼力、后坐位移和后坐速度规律。最后,分析了不同气隙宽度与内筒的电导率对电磁阻尼力的影响,结果表明气隙宽度越小电磁阻尼力越大,同时过大的内筒电导率会导致电磁阻尼力呈现“马鞍”型。本文研究可为混合励磁式电涡流制退机的工程化应用提供理论基础。