双足型直线超声电机的实验研究

研制了一种新型直线超声电机,首先对其驱动机理进行了探讨,设计了电机的具体结构。其次对振子进行了频率响应实验,模态实验,实验表明电机可有效激励出所需振型。分别测定了电机的频率-速度关系、电压-速度关系、相位-速度关系。电机运行中正反两向运动灵活,工作状态稳定,速度基本与输入电压成正比,可采用调压调速;其最大无负载速度可达76 mm/s,最大输出推力2 N,达到了预期设计的目的。     

面内弯纵型直线超声电机的驱动与摩擦分析

分析了直线超声电机定子的质点切向运动和法向运动，认为等速点（定子质点的横向分速度与动子运动速度相等的点）将椭圆运动接触弧对动子的作用分成了驱动部分和阻碍部分。通过对定子的纵向伸缩振动分析，得知定子质心随着定子的振动而发生颤动，质心的颤动使定子两端的受力不是一个定值，并使定子的驱动足对动子进行跳跃性地驱动，电机定子对电机动子进行跳跃式驱动和粘滑摩擦受到材料刚度、预压力、定子振幅等多种因素的影响。文中的摩擦机理分析也可为其他类型的超声电机的驱动与摩擦分析提供参考。     

双足型直线超声电机的原理分析及结构设计

研制了一种新型直线超声电机,首先对其驱动机理进行了探讨,对定子表面质点椭圆运动的形成进行了分析,结合电机输入电压信号的时序阐明了电机工作模态的激发过程;其次对电机结构进行了设计,确定了振子尺寸,组装了一台直线超声电机.     

斜动子与塔形定子构成的单驱双动超声电机

针对两相超声电机对模态频率一致性要求高及单相超声电机难于实现双向运动等问题,提出了一种单相驱动双向运动斜动子塔形直线超声电机。动子相对于塔形定子倾斜安装,利用塔形定子的面内对称模态或面内弯曲模态为工作模态,通过切换工作模态改变定子驱动足运动轨迹相对于动子的倾斜方向,实现动子正、反向运动。在分析电机工作原理及设计原则的基础上,推导了电机运行的导轨倾角适用范围,对设计制作的原理样机进行了模态实验和机械特性测试。实验表明,在导轨倾斜角为35°,激励电压为500 V,预压为力4.5 N的条件下,面内对称振动模态工作时的最大空载速度为79 mm/s,最大输出力为0.5 N;面内弯曲模态工作时的最大空载速度为756 mm/s,最大输出力为0.8 N。     

双足反向型直线超声电机的优化设计及性能仿真

为实现成对微部件反向同步动作的精密定位,设计了一种双足反向型直线超声电机。该电机以矩形板面内一阶纵振和二阶弯振模态为工作模态,通过三角形结构将激励振动放大并在驱动足位置形成椭圆运动,从而驱动两滑条实现反向直线输出。基于工作频率一致性要求进行了电机结构优化,采用谐响应分析验证了设计的可行性。建立定子滑条刚柔接触有限元模型,实现了电机输出性能的仿真。仿真结果说明该电机具有较好的稳定性,空载速度和输出推力分别达到120mm/s和30N。     

单模态驱动的V形板结构直线超声电机

为克服双模态超声电机频率一致性的限制和进一步提高V形直线超声电机的输出性能,设计了一种板结构直线超声电机。该电机包括V形定子和直线导轨,定子由2个相互垂直的板结构振子构成,驱动足位于2个变截面梁的连接点上。利用两振子弯曲振动形成的对称和反对称模态,通过两相模态切换,实现电机的双向运动。研制了样机并对其进行了模态实验和机械输出特性测试。借助三维激光测振仪分别测试了驱动足在接触和不接触导轨情况下的运动轨迹,阐述并验证了单模态超声电机的驱动机理。实验结果表明,该电机具有良好的机械输出特性:最大空载速度为690 mm/s,最大推力达100 N,推重比达59.7。     

摩擦驱动型压电叠堆直线电机的工作原理

以一种典型的摩擦驱动型压电叠堆直线电机结构为例,对摩擦驱动型压电叠堆直线电机的振动摩擦驱动机理进行研究。结合电机系统的振动脱离模型,分析了电机定子与动子脱离的力学条件,进而分析电机结构参数和工作参数对椭圆运动和振动脱离性能的影响。对原理样机进行了试验研究,结果表明,压电叠堆的激励电压、激励频率和电机的预压力对电机的振动脱离性能有显著影响。     

摩擦驱动型压电叠堆直线电机的工作机理

以一种典型的摩擦驱动型压电叠堆直线电机结构为例,对摩擦驱动型压电叠堆直线电机的振动摩擦驱动机理进行研究.结合电机系统的振动脱离模型,分析了电机定子与动子脱离的力学条件,进而分析电机结构参数和工作参数对椭圆运动和振动脱离性能的影响.对原理样机进行了试验研究,结果表明,压电叠堆的激励电压、激励频率和电机的预压力对电机的振动脱离性能有显著影响.     

低压驱动Ⅴ形直线超声电机的设计

针对传统Ⅴ形直线超声电机驱动电压较大、驱动电路复杂,在配合变压器驱动时不利于结构微型化的问题,提出了一种利用叠层压电陶瓷驱动的低压Ⅴ形直线超声电机。在对Ⅴ形直线超声电机的运行机理进行理论分析的基础上,设计了基于叠层压电陶瓷的Ⅴ形振子并进行了夹持装置的结构设计,进一步制作样机并开展了阻抗实验,测试了样机的外输出特性。实验结果表明:电机的驱动频率位于36～38 kHz,在37 kHz,50 Vpp的驱动电压激励下,其最大输出力为25.8 N,最高空载速度为1.221 m/s,可在低压驱动下输出大推力,直线超声电机的驱动性能得到了提高。     

圆柱形多自由度超声电机椭圆倾角和接触角的研究

定子驱动端面形成的椭圆运动是实现超声电机驱动的关键，因而椭圆运动的性质直接影响超声电机的性能。分析了圆柱形多自由度超声电机驱动点的椭圆运动轨迹及其特点。在此基础上给出了椭圆倾角的计算公式，分析了椭圆倾角与接触角之间的关系，得到了最佳接触角。提出了保证最佳接触角的方法。通过实验，分析了接触角对电机输出性能的影响。     

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.     

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。     

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....     

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.