双定子-双转子型大力矩超声波电机的研制

针对单定子-单转子环形行波型超声波电机的输出力矩小,无法满足大力矩驱动应用要求,提出了采用双定子-双转子结构构造大力矩超声波电机的思想。在保证驱动电源和定子直径不变的条件下,通过增加电机轴向长度,采用单轴共轴的形式将两个转子的力矩并联输出,达到提高电机输出力矩的目的。采用基于结构摄动理论的结构修改法对新型电机两定子的工作频率进行了调谐研究。实验结果证明,新型电机的两定子的谐振频率具有良好的一致性,堵转力矩达到1.1N.m,较同型号的传统超声波电机堵转力矩增大近一倍,表明该电机具有较好的输出性能和实际应用前景。     

二自由度超声波电机惯性驱动研究

设计了采用单相电源驱动旋转和直线两种运动的新型单定子二自由度超声波电机,提出了一种近谐振点平稳惯性冲击的电机驱动方法。基于电机构造机理和驱动原理,建立了电机惯性驱动模型,定量分析了方波信号参数对电机性能的影响。算例分析表明,电机在近谐振点采用非对称方波激励,定子端面可输出符合惯性驱动要求的锯齿波。给出了最佳的方波驱动频率与占空比。该驱动方法简洁高效,完全消除了相位差对多自由度电机性能的影响。     

超声波电机谐振升压式驱动电源的研究与设计

从超声波电机的等效电路出发,研究了超声波电机谐振升压式驱动电源的工作原理,设计了电路并利用Multism进行了仿真实验及电机驱动实验,实验结果证明了该方案的可行性和有效性.     

单振子二自由度超声电机驱动电源

设计了用于平板形单振子二自由度超声电机的驱动电源,并针对驱动电源电流负荷较大,输出功率利用率不高的问题,提出了优化驱动性能的措施.该电源利用压控振荡器产生正弦小信号,经高压及功率放大后得到较高的驱动电压及较大的驱动电流实现电机驱动.根据压电振子等效电路模型及工作特性,采取与超声电机并联电感的方法优化了电源驱动性能.制作了驱动电源样机,并对输出性能及优化效果进行了测试.测试结果表明:设计的电源驱动电压及频率可独立连续调节,可输出理想的正弦信号波形;在49.127 kHz、49.756 kHz两种频率下,接超声电机负载时,最大输出电压分别为176.0 V及171.2 V;超声电机并联1.442 mH电感后,电源驱动电流可减少至原来的7.27％和7.41％,功率因数可提高至0.968和0.9550.得到的结果显示,设计的电源满足超声电机驱动要求,采取的优化措施在减小电源电流负荷及提高电源输出功率利用率方面效果明显.     

一种适用于压电超声波电机的变频调速装置

压电超声波电机的工作原理及其驱动控制方式不同于传统电磁型电机，本文针对该电机的驱动要求，采用脉宽调制技术，研制了一套适合于该电机的PWM变频调速装置，对该装置各组成部分分别作了介绍。实验结果表明，所研制的PWM变频调速装置符合压电超声波电机的驱动要求。     

基于锁相环电路的超声波电机频率跟踪系统

因各种原因,超声波电机在运行过程中会发生谐振频率漂移现象,进而导致电机转速下降、效率降低,因此,为了实现超声波电机驱动电源频率跟踪的功能,提出了相位差比较法,即保持电机一相驱动电压与电流的相位差恒定不变,来达到频率跟踪的目的,并采用锁相环(PLL)CD4046实现了超声波电机的频率跟踪.最后通过实验验证了该方法的可行性.     

双柔铰导向式双足压电直线电机的驱动电源设计

为了实现双柔铰导向式双足压电直线电机连续和步进2种作动模式,电机的驱动电源需要产生不同类型的驱动信号,并且通过改变驱动信号的幅值或频率可以改变电机的运行速度。根据该驱动要求采用嵌入式微处理器PSoC作为信号发生单元,应用直接数字式合成器技术产生3种模式的4路驱动信号,利用LM358构成的两级电压放大电路,再通过IRF630构成的功率放大电路对信号进行电压与功率放大。实验表明,该驱动电源能够输出不同模式的信号,输出电压幅值调节范围为0~120V,频率调节范围为0~2kHz,能够实现电机的工作模式、运行速度与运行方向的调节。     

三相反应式步进电机的高性能驱动电源

提出了一种可变细分的高性能步进电机驱动电源，该电源用于驱动三相反应式步进电机。细分波形由AT89S52单片机控制DAC0832数／模转换器产生，驱动单元采用高压型恒流斩波电路。该电源在控制步进电机转动时，微步精度高，低速运转时电机振荡小，高速运转时输出力矩大。通过选择合适的细分数，可与不同档次的CNC控制器配套使用。批量使用结果表明，该电源稳定性好、性价比高，具有一定的推广使用价值。     

一种新型超声电机驱动电源的研究

介绍了一种直接用市电供电的超声电机驱动电源的基本原理及其工作方法。该电源采用脉总宽度调制的方法,用一级功率电路得到稳定的高频高压信号。文中详细介绍了控制信号的产生及反馈网络的相位补偿的方法,使输出信号稳定且满足驱动超声电机的需要。     

超声波电机新型驱动电路的研究与设计

由于超声波电机的工作原理及其驱动控制方式不同于传统的电磁型电机,针对超声波电机的特点及其驱动要求,研究并设计了一套用于实现频率跟踪及调速的新型装置,文中对该装置中硬件电路部分的实现作了较详细的介绍。实验结果表明所设计的硬件电路性能稳定,达到了预期的目的。     

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.     

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....     

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。     

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.