基于GMA喷嘴挡板伺服阀的动态特性

提出基于GMA喷嘴挡板伺服阀的新结构,研制了GMM电－机械转换器及其喷嘴挡板伺服阀,分析其结构特点与需要解决的关键技术,建立动态数学模型。构建基于GMA喷嘴挡板伺服阀动态特性的试验系统,试验研究GMA喷嘴挡板伺服阀的阶跃和幅频响应特性,试验测得其阶跃响应上升时间为1 ms、幅频宽达680 Hz;将试验结果与仿真结果进行对比分析,两者基本吻合,论证动态数学模型的正确性。研究结果表明,用GMM设计新型电—机械转换器,可提高喷嘴挡板阀乃至整个电液伺服系统的频响和精度。     

新型旋转比例电-机械转换器静态特性研究

针对传统旋转电-机械转换器静态特性线性度不高、工作范围小的问题,设计了一种新型旋转比例电-机械转换器,采用磁路解析、Maxwell 3D静磁场有限元分析和实验测试等方法研究了旋转比例电-机械转换器的静态特性,并加工了样机,进行了相关实验研究。实验结果表明,电-机械转换器工作范围为-5～5°,最大输出力矩约为±252 m N·m,具有正的磁弹簧刚度,实验与仿真的差值集中在9. 6 m N·m以内,相对误差基本小于6%;电-机械转换器具有良好的重复精度,转角-力矩特性曲线非线性误差小于1. 5%,滞环小于3. 5%,电流-力矩特性曲线具有很好的线性度及较小的滞环,测试结果与仿真结果基本一致。     

电液伺服阀用新型驱动器特性研究

研究了电液伺服阀用压电型电-机械转换器的驱动特性，分析计算了其输出力和输出位移。对驱动阀芯所需的驱动力进行了计算，在此基础上选择了转换器的驱动元件及放大环节的相关参数。对转换器的输出力特性及输出位移特性进行了测试，建立了二者之间的关系曲线。     

高速比例电磁阀电-机械转换器动态特性研究

在对一种新型的高速比例电磁阀电-机械转换器工作原理分析的基础上,采用了理论建模、仿真分析的方法,得出了在PWM驱动情况下电-机械转换器不同的绕组电流、电感、感应电动势、衔铁位移和速度以及电磁力的响应曲线。通过与试验的电流响应曲线相对比分析:该电-机械转换器结构简单、可靠,电流响应速度大约为0.5 ms,最大输出位移0.2 mm,仿真结果与试验结果基本一致。     

动铁式力马达高频性能研究

一、前言高频大流量电液伺服阀中,电—机械转换器是关键部件。提高电—机械转换器的频响和带载能力是提高电液伺服阀频响的一个前提。动圈式力马达线性度好,推力较大、无磁滞和涡流等问题,且动圈与伺服阀芯可连接成     

伺服阀用压电型驱动器研究

研制了一种压电驱动的电-机械转换器,用于构造电液伺服阀;介绍了电-机械转换器的工作原理;优选了结构型式及尺寸,并对其动静态特性进行了测试。测试结果表明,所设计的电-机械转换器有较好的静态特性及动态特性。在开环方式反向控制算法下,静态特性中的非线性度小于1.6%,在电压范围为0~70V内的滞环小于2.3%,动态响应频宽达1.0kHz以上。由此可见,所设计的电—机械转换器有望替代现有的电磁力矩马达。     

超磁致伸缩电—机转换器位移感知模型及滞环分析

超磁致伸缩电—机转换器响应快、可靠性高,但动态驱动时,因受磁滞、涡流等因素影响,输出位移的滞环较大。需要以准确的数学模型为基础,通过控制算法来补偿滞环,或通过优化其结构参数来降低滞环。通过实时测量超磁致伸缩棒上所绕线圈两端的感应电压和推导此感应电压与超磁致伸缩电—机转换器输出位移的关系,建立实时反映超磁致伸缩棒磁化状态的超磁致伸缩电—机转换器动态位移感知模型,并进一步推导出了超磁致伸缩电—机转换器输出位移的滞环与其结构参数的关系。通过与试验结果对比,当驱动频率小于300 Hz时,由所建模型计算出的位移峰—峰值的相对误差小于5.8%;通过仿真研究超磁致伸缩电—机转换器结构参数对输出位移滞环的影响,得出增加预压弹簧的刚度,可以降低动态驱动时的滞环。     

超磁致伸缩电-机械转换器模型分析

讨论超磁致伸缩电－机械转换器集中参数机电模型及滞回特性模型建模方法。建立的超磁致伸缩电－机械转换器集中参数模型在中低频段能反映其动态行为,滞回特性模型能有效描述电－机械转换器的电流－位移滞回关系。仿真结果与实验特性能很好地吻合,表明提出的２种模型是有效的。     

新型双向比例电-机械转换器的研制

提出一种永磁极化、具备双向驱动能力的电-机械转换器,其工作原理是基于极化磁通与控制磁通的差动叠加控制;分析了其磁场分布及位移-力输出特性。实验结果表明该力马达具有耐高压能力、良好的线性度、较小的滞环和较高的频响,可应用于比例阀或伺服阀。     

新型比例阀用动磁式电机械转换器输出特性分析

介绍了一种永久磁铁励磁的新型阀用动磁式电机械转换器,通过采用动磁式设计和异形导磁心设计,提高了动态响应速度。基于Ansoft Maxwell 2D软件,对电机械转换器的静态性能和动态性能进行了仿真分析。分析表明,该电机械转换器输出力平稳,线性度高,动态响应迅速,可以满足高响应比例阀的驱动要求。     

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...     

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。     

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.     

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....     

Limits of topographic measurement by the scanning tunnelling and atomic force microscopes

Parameters describing the topographic character of a surface (height, surface wavelength, slope and curvature) can be derived from equivalent sinusoidal profiles. The response of a surface-measuring instrument may be modelled in terms of instrument parameters such as stylus radius, and scanning range and resolution. The performance of the instrument may then be mapped as a zone in amplitude-wavelength (AW) space to show the sinusoidal profiles it is capable of measuring. In a first-order analysis the STM and AFM are considered as equivalent to contact-stylus instruments with a notional stylus radius equal to the tip radius plus the gap. Comparisons between different instruments and types of instrument are readily made by mapping in AW space. The error arising from convolution of the sinusoidal profile with that of the finite tip may be quantified and plotted as contours in AW space.