振弦式传感器信号采集卡的研制

介绍振弦式传感器的数学模型及工作原理,给出了该传感器信号采集卡的设计方案。分析了激振与拾振电路的设计,传感器信号频率的等精度测量电路设计,以及采用CAN总线实现与主控卡相互通信的智能节点设计。该采集卡作为一个嵌入式智能单元,可实现根据不同应用需要与其他传感器采集卡自由组合,构成一个灵活的集成数据采集系统硬件平台。     

基于USB的通用虚拟仪器平台开发

结合化工生产过程监控中多参数检测的需要,采用USB数据采集和Delphi软件技术,开发了可对温度、压力和转速多通道数据实时采集和显示的虚拟仪器平台.由于采集卡本身设计质量原因,采集卡输入信号通道和传送至上位机缓存的数据顺序并不完全一致,给后续采集电压信号转换为实际测量信号带来困难,因此结合信号方差和接线方式设计了通道智能判断程序模块,其他数据采集、转换和分析子程序也均采用模块化设计,进一步提高了虚拟测试平台对不同USB采集卡和采集任务的通用性和稳健性.     

基于虚拟仪器的旋转轴扭振测试系统的设计与研究

利用虚拟仪器技术设计开发了旋转轴扭振测试系统,并结合ATI2000系列扭振传感器进行了实际测量,实验结果表明该系统可实现传动轴扭振宽频率、宽转速、多通道同时测量及在线分析等功能,且操作方便、灵活性强,为今后测试和研究大型旋转机械的扭振特性及实现扭振在线监测、故障诊断等提供了理论与技术支持.     

面向故障诊断的行星齿轮扭振信号测量与分析

行星齿轮箱的运行状态对直升机飞行安全非常重要。行星齿轮箱常工作在恶劣的条件下,容易出现磨损或疲劳裂纹等故障。为实现基于扭振信号的行星齿轮传动故障诊断,采用基于增量式编码器的扭振信号测量方法,分别测量了输入轴和输出轴的扭振信号,并分析对比了信号对齿轮故障的敏感性,结果表明,输入轴信号较输出轴信号能更准确地诊断故障。分析比较了负载对信号的影响,认为在重载情况下输出轴扭振信号比输入轴扭振信号对故障特征更加敏感。     

基于SIMPACK的多级齿轮传动机构动力学特性分析

比较研究齿轮模型的建立方法,并在此基础上应用SIMPACK建立一种汽车传动系统的多级行星齿轮机构动力学模型,分析该机构中齿轮动力学建模的关键参数。为了分析这种机构的强迫扭转动力学特性,在输入轴上建立输入通道及其激振器,使之产生振动激励,在输出端建立输出通道,用以绘制扭振响应幅值曲线,最后进行了强迫扭振特性分析。     

一种基于PC104+总线的同步数据采集系统

本文所阐述的数据采集系统,根据某直升机模型着水试验的数据采集需求而研制,试验过程中产生了大量的各种信号类型的数据。该采集系统采用了基于PC104+总线的多采集卡进行采集通道的扩展,以实现多通道多信号类型的数据采集,每套采集卡配置独立的PC104+主板和硬盘存储系统,采用外部控制的方式实现数据采集的同步。采集系统软件设计采用VC++程序语言。     

基于虚拟仪器的振动攻丝机振动参数测量

对于机械式振动攻丝机,当主轴在回转振动的同时还有回转运动和轴向移动,振动参数的测量是困难的.主要的困难是振动信号的提取.将等幅摆振信号通过正弦变化率调制,得到了振频不变、振幅变为不等幅的扭振信号.调制后的扭振信号包含振频和振幅信息,采用虚拟仪器技术可以从调制后的信号中得到振幅和振频.由于位移传感器的测量范围大于扭振振幅的范围,该测量仪要求较高的A/D转换精度.该仪器可以实现在线实时标定.采用信号调制技术与虚拟仪器技术相结合,解决了振动攻丝机振动参数测量问题.经试验证明,该测量原理是可行的.     

基于斑马带的转子系统轴系扭振测量技术

轴系的扭转振动会产生剧烈的应力变化,引起转轴的疲劳裂纹,严重的情况下会导致转子断裂,对扭振的准确测量是诊断转子系统故障的基础。采用斑马带作为转子轴系的编码系统,测量了转子系统扭转振动下的瞬时速度和扭振角度,证明了所采用的斑马带条纹不均匀补偿方法的有效性,并将该扭振测量方法应用于转子系统的碰磨故障诊断。     

汽轮发电机组转速扭振分量极小化的组合方式研究

针对转速滤波器影响系统低频性能的缺点,提出了扭振分量极小化的概念,由于对刚性转速没有相移,它在减少反馈转速中的扭振分量的同时不影响系统低频性能。使用扭振分量极小化后的转速做反馈,减少了考虑扭振后调节系统设计的约束,设计的调节系统可以有高的响应速度而不会影响扭振稳定性。提出了组合方式实现扭振分量极小化方法,分析了这种方法鲁棒性,并使用工业现场数据进行了验证。     

船舶推进轴系扭振模拟实验系统研究

根据船舶扭振的特点,采用模块化设计,开发船舶推进装置的扭振模拟实验平台;以齿盘和光电开关为传感器,NI的信号调理箱、数据采集卡等为主要器件实现扭振信号的采集;基于LabVIEW软件构建扭振监测系统。该系统实时监测推进轴系的振动情况,同时对振动信号做时域分析、频域分析和相位分析等。实验还模拟了激振力、负载等原因引起的扭振情况。实验结果表明,该方案实现了设计的目标,较好地满足了教学及科研需求。     

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。     

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.     

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.