交流电磁机构三维动态特性有限元仿真分析

电磁机构的动态特性分析对于其优化设计至关重要,为了提高电磁机构设计时的整体性能指标,文章利用COMSOL Multiphysics 5.0软件,提出一种交流电磁机构的三维动态过程有限元仿真模型,不仅可以在三维视图下直观观察衔铁运动的整个过程,而且可以获得任意时刻的线圈电流、磁场分布、电磁吸力、衔铁位移与速度等参数。模型针对不同的线圈电压初相角与线圈匝数进行了动态过程仿真,结果显示,线圈匝数决定激磁电流大小,电压初相角对衔铁闭合时刻的运动速度及触头弹跳有较大影响。     

电磁齿轮传动系统动态仿真研究

电磁齿轮传动是一种新型非接触传动技术,通过Pro/E建立三维实体模型,采用机械振动的理论和方法建立电磁齿轮系统的动力学模型,进行了电磁齿轮动态性能参数的研究,在利用有限元软件ANSYS进行静态分析的基础上,以动态仿真软件ADAMS为研究平台,并在Matlab中的Simulink进行运动仿真,最后通过理论分析得出相应结论,为深入研究电磁齿轮传动系统动态特性提供了理论参考。     

基于ADAMS的立体车库举升臂运动学研究

为研究垂直升降门式移动类立体车库举升机构运动规律和活塞杆的受力情况,运用UG三维绘图软件对举升机构进行了三维建模,利用ADAMS仿真软件对举升机构进行动态特性分析,得到活塞杆与提升臂的速度位移曲线,并测试出最大受力点和最大力值。     

循环加热式空气源热泵热水机组测量不确定度评定

以热泵热水机组为例,分析了热泵热水机组测量不确定度的主要不确定度来源,并以测试数据为基础,对具体的测试数据进行了不确定度评定,找出不确定度的主要分量,为提高测试系统的精度提供参考。     

双环控制电动舵机系统的设计验证

针对空空导弹的电动舵机系统,提出了基于传动机构主模态的控制方案,并利用机构动态特性匹配和主模态法设计了双环控制系统。对曲柄滑块机构中的连杆进行分析,利用机构动态特性匹配和主模态方法将高阶多自由度动力学模型简化为二自由度自由转子模型。对二自由度模型与控制系统联合建模,分析机构在有无阻尼状态时谐振主频对系统开环截止频率的影响,确定了按照无阻尼状态进行系统设计更为可靠。最后,对传动机构进行了模态测试,确定了机构动态特性匹配设计方法的可行性。结合风洞测试数据在全弹道飞行平台上对含机构主模态的舵机系统进行了性能验证。模态测试结果表明:固支舵面第一阶扭转频率为1 210.47rad/s,传动机构(含舵面)第一阶扭转频率为1 148.17rad/s,与理论1 180.0rad/s结果一致。全弹道飞行平台外载荷验证显示:最大铰链力矩为6.8Nm时,舵面弹性转角为1.1°,舵机跟踪自驾仪指令最大误差为±0.1°,这些结果满足舵机系统对性能指标的要求。     

高速冲床肘节机构的运动特性研究

针对传统曲轴式高速冲床难以获得理想冲压曲线的问题,以帅锋公司Best-30肘节式高速冲床为例,对肘节机构的运动特性进行了理论推导、仿真分析和试验测试研究。用杆组分析法推导了肘节机构滑块的运动学方程,对肘节机构各连杆进行了动态静力学分析;利用ADAMS软件对肘节机构进行了运动学和动力学仿真分析,并研究了不同曲柄长度、转速对运动特性的影响;最后搭建了测试平台,进行了滑块的下死点精度测试,结合测试结果对仿真结果进行了验证。研究结果表明:肘节机构的运动特性明显优于曲柄滑块机构,下死点加速度减小了52.92%,速度最值增大了13.34%;肘节机构急回特性好,回程时间为去程时间的1/2;下死点动态位置精度高,瞬时精度小于0.004 mm,长时精度小于0.02 mm,满足精密级冲床要求。     

基于ADAMS的递纸机构动态性能分析研究

分析研究了1142型大全张印刷机递纸机构的动态特性,利用Pro/E建立了三维实体模型,应用多体动力学软件ADAMS建立了下摆式递纸机构模型并进行运动学和动力学仿真分析,确定了递纸摆臂的角位移动态响应误差,从而保证纸张定位和交接精度,为递纸机构优化设计提出方法。     

液压支架电液换向阀动态特性测试系统

在研制和生产液压支架换向阀过程中必须对阀的多种参数进行动态测试,论文对电液换向阀的动态特性测试方法进行研究,建立了新型测试系统.实现了在对被试阀施加典型信号后,阀门的进液口和回液口压力流量以及阻力损失的特性等多种电液换向阀的动态参数的测试.采用了虚拟仪器技术,对多个测试数据的同时进行采集、处理、显示和存储等.最后通过实验得到了电液换向阀的动态测试数据.     

工业机器人运动学参数标定误差不确定度研究

为研究机器人末端定位不确定度分布规律,采用不确定度误差的评价方法对工业机器人标定方案得到的运动学参数进行了分析.采用基于各轴单独旋转拟合空间曲线的方法,解算获得运动学参数模型.在机器人标定模型的基础上,分析出各项运动学参数标定结果的不确定度.分析了各轴关节转角θ对不确定度的影响规律,并实验研究各轴在标定或者动态测量过程中,测量点数及测量角度等条件对测量不确定度的影响.推导出机器人末端位置误差不确定度的计算方法,并分别以机器人某一固定姿态和固定路径为例,研究了机器人末端位置误差的不确定度.采用激光跟踪仪做为闭环测量设备,实验验证了单轴运动空间曲线拟合方法,可有效地估计在整个机器人工作空间内的运动误差不确定度分布,标定后在x、y、z3个方向上定位不确定度分别为0.356 mm、0.582 mm和0.524 mm.     

三自由度运动平台的运动仿真及控制设计

通过对并联机构的三自由度运动平台的正逆解分析,采用VC++,以OpenGL为图形API,并利用坐标系变换的方法,实现了运动机构的参数化和实时动态的三维可视化仿真。根据仿真结果,利用MPC2810运动控制卡,提出了以直代曲的运动控制方法,为实际的机构运动控制提供了必要的理论依据。     

Minimal Realization of Linear Graph Models for Multi-physics Systems

An engineering system may consist of several different types of components,belonging to such physical"domains"as mechanical,electrical,fluid,and thermal.It is t...     

INTEGRAL EQUATION METHOD＇S APPLICATION IN HOLE-EDGE STRESS OF COMPOSITE MATERIAL PLATE WITH DIFFERENT SHAPED HOLES

The strength of composite plate with different hole-shapes is always one of the most important but complicated issues in the application of the composite material. The holes will lead to mutations and discontinuity to the structure. So the hole-edge stress concentration is always a serious phenomenon. And the phenomenon makes the structure strength decrease very quickly to form dangerous weak points. Most partial damage begins from these weak points. According to the complex variable functions theory, the accurate boundary condition of composite plate with different hole-shapes is founded by conformal mapping method to settle the boundary condition problem of complex hole-shapes. Composite plate with commonly hole-shapes in engineering is studied by several complex variable stress fimction. The boundary integral equations are founded based on exact boundary conditions. Then the exact hole-edge stress analytic solution of composite plate with rectangle holes and wing manholes is resolved. Both of offset axis loadings and its influences on the stress concentration coefficient of the hole-edge are discussed. And comparisons of different loads along various offset axis on the hole-edge stress distribution of orthotropic plate with rectangle hole or wing manhole are made. It can be concluded that hole-edge with continuous variable curvatures might help to decrease the stress concentration coefficient; and smaller angle of outer load and fiber can decrease the stress peak value.     

Non-monotonic material contrast in scanning ion and scanning electron images

30 keV Ga⁺ focused ion beam induced secondary electron (iSE) imaging was used to determine the relative contrast between several materials. The iSE signal compared from C, Si, Al, Ti, Cr, Ni, Cu, Mo, Ag, and W metal layers does not decrease with an increase in target atomic number Z₂, and shows a non-monotonic relationship between contrast and Z₂. The non-monotonic relationship is attributed to periodic fluctuations of the stopping power and sputter yield inherent to the ion–solid interactions. In addition, material contrast from electron-induced secondary electron (eSE) and backscattered electron (BSE) images using scanning electron microscopy (SEM) also shows non-monotonic contrast as a function of Z₂, following the periodic behavior of the stopping power for electron–solid interactions. A comparison of the iSE and eSE results shows similar relative contrast between the metal layers, and not complementary contrast as conventionally understood. These similarities in the contrast behavior can be attributed to similarities in the periodic and non-monotonic function defined by incident particle–solid interaction theory.     

Application of Feature Extraction through Convolution Neural Networks and SVM Classifier for Robust Grading of Apples

This paper proposes a novel grading method of apples,in an automated grading device that uses convolutional neural networks to extract the size,color,texture,an...     

分布动态载荷识别的抗噪处理

针对正交多项式频域法在用多种响应对矩形薄板进行载荷识别中抗噪性较差的问题,综合运用平均法、矩阵预处理和奇异值截断法等方法对之进行改善,并引入空间映射的思想,将该方法的应用范围拓展为复杂的模型.利用仿真算例,证实了该方法具有较好的抗噪性.     

Short-Term Relay Quality Prediction Algorithm Based on Long and Short-Term Memory

The fraction defective of semi-finished products is predicted to optimize the process of relay production lines, by which production quality and productivity ar...     

End-to-End Multiview Gesture Recognition for Autonomous Car Parking System

The use of hand gestures can be the most intuitive human-machine interaction medium.The early approaches for hand gesture recognition used device-based methods....     

基于MELTAC-N平台的核电厂安全级DCS环网研究与测试

针对工程实践中环网通讯相关问题的处理缺乏理论基础及国产化安全级DCS平台的开发缺乏成熟经验借鉴问题,对基于MELTAC-N平台核电厂安全级DCS环网的软硬件实现进行了研究。提出了安全级DCS环网双环网冗余设计、光切换开关设计等硬件设计方法,以及以RPR协议为基础,采用全数据收发策略的软件设计方法。在CPR1000安全级DCS平台上对安全级DCS环网的可靠性及实时性进行了评价,并进行了容错能力、响应时间及响应时间稳定性测试验证实验。结果表明,基于MELTAC-N平台安全级DCS环网软硬件设计具有较好的容错能力及响应时间稳定性。     

The laboratory simulation of abrasive wear

Abrasive wear has long been recognised as one of the most potentially serious tribological problems facing the operators of many types of plant and machinery; several industrial surveys have indicated that wear by abrasion can be responsible for more than 50% of unscheduled machine and plant stoppages. Locating the operating point of a tribological contact in an appropriate operational ‚map’︁ can provide a useful guide to the likely nature and origins of the surface degradation experienced in use, though care must be exercised in choosing the most suitable parameters for the axes of the plot. Laboratory testing of materials and simulations of machine contacts are carried out for a number of purposes; at one level for the very practical aims of ranking candidate materials or surface hardening treatments in order of their wear resistance, or in an attempt to predict wear lives under field conditions. More fundamentally, tests may be aimed at elucidating the essential physical mechanisms of surface damage and loss, with the longer term aim of building an analytical and predictive model of the wear process itself. In many cases, component surface damage is brought about by the ingress of hard, particulate matter into machine bearing or sealing clearances. These may be running dry although, more usually, a lubricant or service fluid is present at the interface. A number of standardised wear test geometries and procedures have been established for both two- and three-body wear situations, and these are briefly described. Although abrasive wear is often modelled as following an ‚Archard’︁ equation (i.e. a linear increase in material loss with both load and time, and an inverse dependence on specimen hardness) both industrial experience and laboratory tests of particularly lubricated contacts show that this is not always the case: increasing the hardness differential in an abrasively contaminated lubricated pair may not always reduce the rate of damage to the harder surface.     

ANGULAR DISTORTION ALLOWABLE VALUE AND ASSESS METHOD OF WELD ON COKE TOWER

A graph as the new engineering method for estimate the safety of bulging deformation of coke tower is proposed. Through stresses analysis of circumferential weld of coke tower and comparing the stresses produced by pressure with heat stress of steady state, residual stress, bending stress produced by both itself weight and wind loads, it showed that the stresses produced by pressure on the angle distortion are the main factor of equivalent stress of the combined stress. After comparing four kinds of stress controlling conditions, the relation to stress with depth of angular distortion, grade of curvature of angular distortion and half of region of angular distortion has been inferred. Graph of deformation allowable value of coke tower for different condition by angular distortion and half of region of angular distortion has been plotted. The five steps for its engineering use have been explained. The lighter the grade of curvature is, the larger of bulge allowance, may be, and the bigger of depth of angular distortion may pose too. For the coke tower with a popular structure of Dg 5 400 mm×28 mm, the result by graph is nearly more than the result of two formulas formed by other research, the error is less than 7.0%. But, the graph can be easily applied to different size of angular distortion.