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。     

用于精密定位平台的直线超声电机的异步并联

提出了直线超声电机异步并联的概念以提高精密定位平台驱动单元的位移分辨率、输出力及速度.基本原理是若干定子(或振子)在一个振动周期内交替驱动动子(或转子),使实际的驱动频率成倍提高,可以获得更好的输出性能.分析显示,提高定子与动子之间的接触频率可以提高输出力和速度,改善瞬态响应特性,并可避免同步并联方式下定子的相互干扰问...     

可调控正弦超声电源的设计

阐述一种性能优越可调控高效超声电源,利用功率调整芯ICE2PCS01、单片机dsPIC30F6010A实现频率20kHz～35kHz正弦波超声电源,输出电压可调幅值为300V,最大功率为300W。     

基于高频软开关技术的电镀电源设计

本文设计了一种基于高频软开关技术的电镀电源,单机满载输出功率为7.2kW(600A/12V).采用了移相控制和倍流整流技术,在变压器原边加入隔直电容和饱和电感,原边超前桥臂保持宽范围的零电压开通条件,滞后桥臂实现了无环流损耗的零电流关断:副边的倍流整流方式,两个二极管实现了自然换流,两个输出电感交错并联的方式,大大减小了系统电流纹波,减小了电感的尺寸,从而减小系统的体积和重量;运用均流控制芯片UC3907设计了电源模块的均流控制电路,实现了多模块并联组成大功率的电镀电源系统,提高了电源输出性能.     

四腔并联压电泵结构设计

为提高压电泵的输出性能,设计了一种层叠型四腔并联有阀压电泵。在80 V正弦交流电驱动下,40~400 Hz工作频率内,以水和空气作为介质,分别选用不同数量的压电振子进行驱动,在不同的驱动方式(指振子间工作时的相位差)下对泵的输出性能进行试验测试。结果显示,当泵送空气时,不管多少个振子进行驱动,驱动方式对泵的输出流量几乎不产生任何影响,在测试频率范围内,输出流量随频率成线性变化,最大输出气体流量可达3600 mL/min;当泵送液体时,驱动方式对泵的输出流量影响很大,当同侧的压电振子为异步驱动时,输出流量的效果更好,在工作频率180 Hz时,最大输出液体流量可达830 mL/min。试验结果为多振子驱动压电泵选择合适的振子间驱动方式提供了参考依据。     

宽范围调压的超声电机测试驱动电源

测试新超声电机的现有方法是研究专用测试电源,为了避免重复性开发驱动电源引起的研制周期长、材料和人力成本高等影响,研究了宽范围调压的超声电机测试驱动电源。首先,理论分析变压器体积与损耗及频率的关系,确定电源为无变压器结构;其次,分析Boost等效电路推导出升压比存在上限,逆变电路占空比大范围调节会导致交流方波总谐波失真(total harmonic distortion,简称THD)增加。综上确定了测试驱动电源拓扑为可控整流+Boost电路+半桥逆变三级电路,提出了预配置+自动选择性控制策略解决级联电路的稳定性问题。实验结果证明了测试驱动电源能输出2相工作频率在10～100kHz、相位差在±90°内、电压幅值为20～600V的交流电。用TRUM60和直线超声电机作为负载,测试驱动电源能为不同超声电机提供合适的驱动信号和匹配参数,超声电机运行平稳。     

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。     

基于连续高压脉冲方波的绝缘老化试验系统

为研究牵引逆变器输出脉冲电压对变频牵引电机绝缘的影响,根据牵引逆变系统电压波形和加速老化试验原则,采用变压式试验电源研制了一套基于连续高压脉冲方波的绝缘老化试验系统.高压脉冲电源为双极性,脉冲电压峰峰值为0～10 kV,频率为500 Hz～20 kHz,占空比为50%,上升沿时间2 μs左右,输出功率1 kW,温度范围为室温～300 ℃,高压脉冲电源脉冲幅值高、频率可调,具有过流、过压保护功能,完全满足进行变频牵引电机绝缘材料性能试验的要求.     

具有阻抗匹配功能的磁致伸缩换能器驱动电源

磁致伸缩换能器是以磁致伸缩材料为驱动元件的特种电机。其工作电流和输出位移、输出力受磁致伸缩材料的非线性和温度、负载等因素的影响较大。为优化工作电流波形、实现频率闭环,以串联谐振电路为基础,设计了具有阻抗匹配功能的驱动电源,并进行仿真与实验研究,结果显示该电源能够使换能器保持谐振工作状态,同时具有较好的正弦电流波形。     

微动式可调电感设计及其应用

设计了一款微动式可调电感,提供一种应用于超声电源调试中,寻找最佳匹配电感的新方式,以提高超声电源调试效率,降低电源制作成本。以超声振子两端电压和流过其回路电流波形的相位差作为参考指标,对超声电源进行调试实验。实验结果表明:该可调电感能连续可调,有助于在电源调试中方便、快速地得到所需匹配及提高电源调试效率,可满足超声电源实际调试应用要求。     

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...     

Quantum Cooperative Robotics and Autonomy

The intersection of Quantum Technologies and Robotics Autonomy is explored in the present paper.The two areas are brought together in establishing an interdisci...     

考虑进油孔有限长滑动轴承油膜力的近似解析解

针对具有进油孔的有限长滑动轴承油膜力求解问题,采用变分原理和分离变量法,求得了有限长滑动轴承油膜压力分布的近似解析表达式。将油膜压力分布的近似解析表达式在油膜存在区域上进行积分,即得到了油膜力。将提出的计算有限长滑动轴承油膜力方法与无限长轴承模型、有限元方法的计算结果进行了比较,发现了提出的方法与有限元方法的计算结果很接近。最后,研究了进油孔位置和进油压力对油膜存在区域、油膜力等的影响,研究结果表明进油孔位置和进油压力对油膜存在区域和油膜力有较大的影响。     

三绕组变压器的双绕组等效建模及在Matpower中的应用

针对实际电网存在着大量的三绕组变压器,但国际上一些著名商业软件,如BPA仿真软件、Matpower这一权威潮流计算开源软件,均只提供双绕组变压器模型,限制了其在具有三绕组变压器的电力系统中的应用的问题,潮流计算是自主开发的电力系统各种应用软件的核心模块,因此依托国际权威开源程序进行二次开发,是一种较好的选择。对Matpower要求的数据格式进行了归纳,对变压器的一般的等值电路及带理想变压器的等值电路和带标幺值的等值电路进行了分析研究,提出了三绕组变压器转换为双绕组等效模型的建模方法,使得原先只适应双绕组变压器的潮流计算软件可以适用于三绕组变压器电网的潮流计算;最后以Matpower软件为例进行了案例计算,并用PSASP仿真软件进行对比验证。研究结果证明,所提出的建模方法是有效的。     

On the Relation of Load to Average Gap in the Contact Between Surfaces with Longitudinal Roughness

A computer simulation model for the contact between longitudinally-oriented rough surfaces has been formulated. This model closely duplicates the actual surf ace contact deformation behavior by taking into account the elastic interactions between the asperities. There were no assumptions made about the shapes, or any deformation behavior of the asperities, except for their obeying the laws of elasticity. The plastic deformations on the high asperity peaks were taken into account by setting a ceiling on their contact pressures at the material hardness value. The simulations used real surface profiles which were digitized from unworn circumferentially ground steel surfaces. Each pair of these profiles was mathematically combined to form an equivalent rough profile pressing against an infinitely rigid flat and having the appropriately adjusted elastic modulus. A total of 28 different pairs of profiles were used in the simulations. Each contacting pair was subjected to 30 different load levels and the local contact pressures and deformations were calculated. The contact simulations yielded some important mathematical relationships between parameters, such as the real area of contact, average gap, and average asperity load through statistical curve fitting. Two analytical functions were generated to relate the average load to average gap and the real area of contact to load.     

Fifth International Summer School on Screw-Theory Based Methods in Robotics

正3-11 September,2014University of Bologna,Bologna,Italy www.summerscrews.org summerscrews2014.ing.unibo.it SUMMER 20SCREWS 14In 2014,our screw-theory school comes to the world's oldest university.In early September,Summer Screws'14 will gather six experts in the application of screw theory in robotics and up to 40 participants at the University of Bologna,Bologna,Italy.The school will teach attendees how to apply existing methods and empower them to develop new ones in their own research.The basic theoretical notions will be introduced in a rigorous manner,emphasizing examples,applications,and exercises.Scholarships are available.     

INDUSTRIAL ENGINEERING AND VISUALISATION-A PRODUCT DEVELOPMENT PERSPECTIVE

Taking the actual project of teaching and researching process for example, the relationship between the industrial engineering and product development is discussed. And use the novel visualization technology to support the industrial engineering and product development. How to use the new computer modeling and simulating technologies to support the product development and industrial engineering, is introduced especially. The support includes both domestic products and industrial systems. The visualization and computer technologies take a very important role in some system or multi-direction modeling, those technologies mentioned above can help the industrial engineers study the effect of design on the whole life circle, including the producing steps. So the engineers can avoid making the wrong decision which may cause bad effects on the whole industrial engineering.     

电站锅炉模糊风险评价方法研究与应用

针对电站锅炉风险等级评价问题,将模糊综合评价技术应用到电站锅炉风险等级评价中。开展了电站锅炉失效影响因素及模糊评价因素的重要程度分析,建立了一套科学合理适于在线评价的电站锅炉风险评价体系,提出了模糊综合评价技术与改进的模糊层次分析法相结合的模糊风险评价方法,利用改进的模糊层次分析法计算了指标体系中各层指标权重。对某一台电站锅炉的实际运行工况影响子因素进行了模糊风险评价,采用模糊合成算子进行模糊综合运算得到电了站锅炉运行工况影响子因素的评价向量。研究结果表明:电站锅炉的运行工况影响子因素的风险评价等级为第6级,失效可能性等级为小,该电站锅炉运行工况良好。     

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...