抑制电磁干扰的悬浮间隙传感器检测线圈结构设计

高速磁浮列车悬浮间隙中存在着牵引磁场、悬浮磁场等多种磁场,它们的高次谐波耦合到检测线圈中容易形成电磁干扰对悬浮间隙传感器造成影响。通过设计8字结构线圈,大幅度抑制了这种共模形式的电磁干扰。针对双检测线圈可能存在相互电磁干扰问题,通过调整双线圈之间相对位置,使两线圈间互感接近于零时,就可消除该种干扰,据此,确定两检测线圈间错位1/3线圈长度,通过试验验证了可行性。     

高速磁浮列车悬浮间隙传感器检测线圈的设计

本文分析了高速磁浮车悬浮间隙传感器齿槽效应的产生和影响,提出并设计了由两个串联线圈组成的新型检测线圈,通过实验验证了新型线圈能够有效地降低齿槽效应。     

高速磁浮列车悬浮间隙传感器的故障检测设计

在高速磁浮列车中,悬浮间隙传感器结构复杂,使用量大,环境温度高,振动较大,传感器易出现故障,因此,维护工作量大;为了解决该问题,提高维护效率,对传感器的振荡电路、信号调理以及通讯等主要环节,分别设计了相位差比较检测、基准信号切换比较以及电平转换比较等电路结构,通过传感器内部测试点与外围检测电路相结合,设计了故障检测系统结构及故障编码;最后进行了部分故障试验验证,达到故障准确定位、降低维护工作强度的目的。     

悬浮间隙传感器的电磁兼容设计

高速磁浮列车悬浮间隙传感器所处的环境电磁场较复杂,各种电磁场通过传导或者辐射有可能干扰传感器;在讨论电快速瞬变抗扰度试验、浪涌抗扰度试验、静电放电抗扰度试验和射频场感应传导干扰的抗扰度试验等电磁兼容试验基础上,在传感器的电源线环节采取了电涌吸收器件加多级滤波的方案来抑制电磁干扰,在信号端口环节采取了暂态电压吸收器和光电隔离的方案来抑制电磁干扰,在检测线圈环节采取了8字型的线圈结构来抑制共模形式的电磁干扰;以上措施在试验中已经得到较好地应用。     

磁浮列车间隙传感器动态特性研究

磁浮列车的控制和运行对间隙传感器动态特性有较高要求.首先,在研究磁浮间隙传感器动态性能与动态特性测试方法的基础上,根据磁浮列车用间隙传感器的原理,对传感器主要环节进行动态建模.接着,通过分析模型函数通解的结构形式,提取了影响传感器动态特性的影响因素,并对传感器动态特性进行了有效补偿.最后,设计了一种模拟开关方法,对传感器动态性能进行试验测试.分析与试验结果表明,传感器动态特性主要受检波电路影响,模拟开关方法可以有效地检测传感器动态特性.     

高速磁浮列车悬浮间隙传感器线圈结构的分析设计

以分子电流学说为基础,提出了一种电感式传感器的等效检测模型,并据此分析了高速磁浮列车间隙检测传感器检测线圈的结构形状与齿槽效应之间的关系,提出了一种能够减弱齿槽效应的线圈结构,并通过实验验证了其有效性.     

高速磁浮列车间隙传感器温度漂移的补偿

为了解决检测线圈电阻受温度影响而导致漂移补偿问题,设计分析了高速磁浮列车间隙传感器电路模型,设计补偿线圈,利用差分方式补偿了温度漂移,同时还分析得出了测量间隙对传感器温度灵敏度影响很小的结论,在传感器空载条件下的建立温度漂移修正表,利用该修正表来补偿传感器的温度漂移,通过这些措施,大大提高了间隙位移传感器输出信号的温度稳定性.     

基于FPGA的高速磁浮列车悬浮间隙测量系统

针对长定子直线同步电机驱动的高速磁浮列车,介绍了一种悬浮间隙测量系统的实现方法,并进行了实验验证;基于电感式传感器理论,该项技术利用新型数字逻辑器件FPGA,实现对高速磁浮列车悬浮间隙的精确测量,检测精度可达0.1 m,满足了悬浮间隙测量系统的要求.     

高速磁浮车间隙传感器齿槽效应补偿方法研究

齿槽效应是高速磁浮车间隙传感器面临的一个特殊性问题。针对齿槽效应带来的齿槽误差问题,提出在传感器探头内布置齿槽位置检测线圈,采用径向基函数(RBF)神经网络建立齿槽效应逆模型,依据位置信号对传感器的输出进行齿槽补偿的方法。仿真结果表明:在2～20 mm范围内补偿器输出最大误差为±0.18 mm,该种方法可以有效地消除齿槽效应,并提高传感器的检测精度,满足高速磁浮车悬浮控制系统要求。     

曲面体间隙电涡流检测的有限元分析

为研究曲面体间隙电涡流检测受目标导体曲率的影响,基于电磁场有限元分析方法对平面线圈用于不同曲率目标导体间隙测量时的交流阻抗进行了数值计算,得到了线圈的归一化阻抗平面图,并讨论了由于曲率不同引起的数据误差处理方法,为曲面体间隙的准确测量提供了理论依据.计算结果表明:保持线圈位置曲面体间的平均间隙不变,当目标导体曲率不同时,平面线圈的归一化阻抗变化近似为一条直线,随曲率增大,线圈的归一化阻抗将沿着远离零曲率点的方向变化,且凹面和凸面时远离的方向相反.     

Efficient reliability-based design optimization using a hybrid space with application to finite element analysis

The design of high technology structures aims to define the best compromise between cost and safety. The Reliability-Based Design Optimization (RBDO) allows us to design structures which satisfy economical and safety requirements. However, in practical applications, the coupling between the mechanical modelling, the reliability analyses and the optimization methods leads to very high computational time and weak convergence stability. Traditionally, the solution of the RBDO model is achieved by alternating reliability and optimization iterations. This approach leads to low numerical efficiency, which is disadvantageous for engineering applications on real structures. In order to avoid this difficulty, we propose herein a very efficient method based on the simultaneous solution of the reliability and optimization problems. The procedure leads to parallel convergence for both problems in a Hybrid Design Space (HDS). The efficiency of the proposed methodology is demonstrated on the design of a steel hook, where the RBDO is combined with Finite Element Analysis (FEA).     

基于有限元分析和结构优化的飞机垂尾质量估算

为在总体设计阶段较准确地估算飞机的质量,以垂尾为研究对象,提出基于有限元分析和结构优化的垂尾质量估算方法.该方法的主要步骤为:用CATIA实现垂尾的参数化定义并生成CAD模型;用AVL软件进行气动载荷分析;用PCL编写程序将CAD模型导入MSC Patran中,并应用其结构优化功能计算得到垂尾质量.在iSight中实现...     

基于有限元的杆端关节轴承结构优化

针对某型号杆端关节轴承在疲劳试验时发生断裂的问题,对其原结构进行有限元仿真分析,得到的最大应力位置与实际断裂位置吻合,圆柱段仿真结果误差与应力理论计算结果仅为0.5%,验证仿真结果的可靠性。对杆端体各结构参数依次进行单变量有限元仿真分析,获取各参数对杆端体最大应力和质量的影响,据此确定优化顺序并对关节轴承进行优化。优化后的杆端关节轴承质量增加9.8%,最大等效应力降低14.9%,计算疲劳寿命从500万次提高到4 600万次,大于目标疲劳寿命值3 000万次,优化后的样件均顺利通过疲劳试验。     

结合环状原型空间优化的开放集目标检测

目的 现有目标检测任务常在封闭集设定中进行。然而在现实问题中,待检测图片中往往包含未知类别目标。因此,在保证模型对已知类检测性能的基础上,为了提升模型在现实检测任务中对新增类别的目标检测能力,本文对开放集目标检测任务进行研究。方法 区别于现有的开放集目标检测框架在检测任务中将背景类与未知类视为一个类别进行优化,本文框架在进行开放集类别识别的过程中,优先识别候选框属于背景类或是含待识别目标类别,而后再对含待识别目标类别进行已知类与未知类的判别。本文提出基于环状原型空间优化的检测器,该检测器可以通过优化待检测框的特征在高维空间中的稀疏程度对已知类、未知类与背景类进行环状序列判别,从而提升模型对开放集类别的检测性能。在（region proposal networks,RPN）层后设计了随机覆盖候选框的方式筛选相关的背景类训练框,避免了以往开放集检测工作中繁杂的背景类采样步骤。结果 本文方法在保证模型对封闭集设定下检测性能的情况下,通过逐步增加未知类别的数量,在Visual Object Classes-Common Objects in Context-20(VOC-COCO-20),Vi...     

基于有限单元法的汽车称重传感器

分析集成化称重板式轮重秤的设计原理，提出采用辐板式称重传感器作为动态称重系统压力元件的设计方案，重点阐述利用有限元软件进行传感器敏感元件模型设计、网格划分、施加载荷与边界条件的过程；根据敏感元件的应力分布规律，找到应变片的布片规律和具体位置，组成全桥差动电路，使车辆轮胎载荷作用在秤台平面的不同区域均可以测出其准确重量．通过传感器的动态响应试验分析其频率响应特性．     

Boundary element analysis of elastic contact problems using gap finite elements

Gap finite elements provide a practical approach for dealing with elastic contact problems, and it is not possible to derive something similar with boundary elements. This work introduces a simple technique for the analysis of elastic contact problems by coupling a gap finite element subregion with boundary element subregions. The developed algorithm proves to be accurate and reliable, combining the advantages within contact problems of both the gap finite element and the boundary element method.     

Guidelines for selecting finite element grids based on an optimization study

The requirements for optimum finite element grids are presented and discussed. The work focuses on the introduction of nodal co-ordinates as independant unknowns, in addition to nodal displacements which have characterized the method in the past. A study is made of optimum grids in two dimensional plane stress problems from which specific guidelines are suggested such that near optimum grids can be selected by the analyst. These grids lead to improved stresses and displacements.     

Design multiple-layer gradient coils using least-squares finite element method

The design of gradient coils for magnetic resonance imaging is an optimization task in which a specified distribution of the magnetic field inside a region of interest is generated by choosing an optimal distribution of a current density geometrically restricted to specified non-intersecting design surfaces, thereby defining the preferred coil conductor shapes. Instead of boundary integral type methods, which are widely used to design coils, this paper proposes an optimization method for designing multiple layer gradient coils based on a finite element discretization. The topology of the gradient coil is expressed by a scalar stream function. The distribution of the magnetic field inside the computational domain is calculated using the least-squares finite element method. The first-order sensitivity of the objective function is calculated using an adjoint equation method. The numerical operations needed, in order to obtain an effective optimization procedure, are discussed in detail. In order to illustrate the benefit of the proposed optimization method, example gradient coils located on multiple surfaces are computed and characterised.     

Research on a new optimization algorithm simulating multi- states of matter inspired by finite element analysis approach

A new optimization algorithm is proposed, since a huge problem that many algorithms faced was not being able to effectively balance the global and local search ability. Matter exists in three states: solid, liquid, and gas, which presents different motion characteristics. Inspired by multi- states of matter, individuals of optimization algorithm have different motion characteristics of matter, which could present different search ability. The Finite Element Analysis (FEA) approach can simulate multi- states of matter, which can be adopted to effectively balance the global search ability and local search ability in new optimization algorithm. The new algorithm is creative application of Finite Element Analysis at optimization algorithm field. Artificial Physics Optimization (APO) and Gravitational Search Algorithm (GSA) belongs to the algorithm types defined by force and mass. According to FEA approach, node displacement caused by force and stiffness could be equivalent to motion caused by force and mass of APO and GSA. In the new algorithm framework, stiffness replaces mass of APO and GSA algorithm. This paper performs research on two different algorithms based on APO and GSA respectively. The individuals of new optimization algorithm are divided into solid state, liquid state, and gas state. The effects of main parameters on the performance were studied through experiments of 6 static test functions. The performance is compared with PSO, basic APO, or GSA for four complex models which made up of solid individual, liquid individual, and gas individual in iterative process. The reasonable complex model can be confirmed experimentally. Based on the reasonable complex model, the article conducted complete experiments against Enhancing artificial bee colony algorithm with multi-elite guidance (MGABC), Artificial bee colony algorithm with an adaptive greedy position update strategy (AABC), Multi-strategy ensemble artificial bee colony (MEABC), Self-adaptive heterogeneous PSO (fk-PSO), and APO with 28 CEC2013 test problem. Experimental results show that the proposed method achieves a good performance in comparison to its counterparts as a consequence of its better exploration– exploitation balance. The algorithm supplies a new method to improve physics optimization algorithm.

     

Recommendations for tool-handle material choice based on finite element analysis

Huge areas of work are still done manually and require the usages of different powered and non-powered hand tools. In order to increase the user performance, satisfaction, and lower the risk of acute and cumulative trauma disorders, several researchers have investigated the sizes and shapes of tool-handles. However, only a few authors have investigated tool-handles' materials for further optimising them. Therefore, as presented in this paper, we have utilised a finite-element method for simulating human fingertip whilst grasping tool-handles. We modelled and simulated steel and ethylene propylene diene monomer (EPDM) rubber as homogeneous tool-handle materials and two composites consisting of EPDM rubber and EPDM foam, and also EPDM rubber and PU foam. The simulated finger force was set to obtain characteristic contact pressures of 20 kPa, 40 kPa, 80 kPa, and 100 kPa. Numerical tests have shown that EPDM rubber lowers the contact pressure just slightly. On the other hand, both composites showed significant reduction in contact pressure that could lower the risks of acute and cumulative trauma disorders which are pressure-dependent. Based on the results, it is also evident that a composite containing PU foam with a more evident and flat plateau deformed less at lower strain rates and deformed more when the plateau was reached, in comparison to the composite with EPDM foam. It was shown that hyper-elastic foam materials, which take into account the non-linear behaviour of fingertip soft tissue, can lower the contact pressure whilst maintaining low deformation rate of the tool-handle material for maintaining sufficient rate of stability of the hand tool in the hands. Lower contact pressure also lowers the risk of acute and cumulative trauma disorders, and increases comfort whilst maintaining performance.