矢量网络分析仪在变频器件群时延测量方面的应用

介绍基于矢量网络分析仪对变频器件的群时延进行测量的方法,以RS公司生产的ZVA和Agilent公司生产的PNA矢量网络分析仪为代表,分别对外接本振变频器件和嵌入式本振变频器件的群时延测量原理进行了阐述,可根据不同的测试需求选择有效的测试方法。     

传动轴扭矩测量误差分析

传动轴扭矩测量是研究车辆动力系统性能的重要手段.介绍了传动轴扭矩精确测量的重要性,给出了影响传动轴扭矩测量精度的一些因素,并详细分析了由传动轴扭矩应变式测量方式、传动轴本身产生的弯矩以及传动系统带来的扭振对测试结果所产生的影响,为下一步更精确地测量传动轴的扭矩打下了坚实的基础.     

复杂工况抽油机变频控制中游梁摆角高精度测量技术研究

针对实际油井工程中游梁式抽油机变频调速的控制问题,为了给其电机速度曲线优化提供高精度的摆角信息,以达到提高变频控制效率及稳定性的目的,设计了用于变频控制器的高精度实时游梁摆角测量系统.在复杂工况条件下,为了提高系统测量精度,采用了防脉冲干扰的移动平均滤波法以及分段补偿温度漂移等技术;同时为了有效消除安装误差,提出了摆角测量系统在线标定方法;最后对游梁摆角进行了静态及动态试验.实验及研究结果表明:在实际抽油机-50°～+50°的摆幅内,系统测量精度达到±0.15°,零偏为±0.05°,且抗振效果非常明显,该系统能够满足油田恶劣工况下电机控制系统变频优化调速的使用要求.     

双频激光三尺组合法直线度测量系统

本文提出一种双频激光三尺组合法直线度测量系统。理论分析及实验结果都说明本系统可望获得优于0.1μm/m的精度,是提高现有直线度测量精度的一个较实用的方法。     

显微式激光多普勒测振系统的开发与应用

提出了一种显微式的激光多普勒测振系统。该系统基于激光多普勒测振原理,综合运用激光外差干涉技术和显微缩束技术,结合电路解调功能实现模拟信号的解调,通过数据采集及算法处理,实现振动信号的波形显示及结果分析。通过与BK-4527型传感器的对比试验表明,该显微测振系统可以很好地实现精确测量。同时,该系统可实现对微机电系统的振动测试和位置定位,弥补了传统激光多普勒测振系统无法测量微小物体振动的缺陷,具有良好的应用前景。     

基于叶端定时的转子扭转振动监测方法及系统研究

随着变频调速技术在压缩机/风机上的应用越来越广泛,由变频器产生的谐波导致的扭转共振问题也越来越突出。本文提出了一种基于叶端定时的转子扭转振动监测方法,设计并开发了集叶片振动及轴系扭转振动于一体的监测系统。本系统利用脉冲时序计数法处理叶片脉冲序列信息,将相邻叶片实际到达时间差与理论到达时间差的差值同叶尖角速度相乘得到轴系扭振角位移。实验结果表明,本文提出的基于叶端定时的转子扭转振动监测方法及系统具有可靠的精度,可用于实际工程测试,为旋转机械扭振测量提供新途径。     

双频激光三尺组合法直接度测量系统

本文提出一种双频激光三尺组合法直线度测量系统，理论分析及实验结果都说明本系统可望获得优于０．１μｍ／ｍ的精度，是提高现有直线度测量精度的一个较实用的方法。     

测量船船体横扭角测量的双频偏振法

针对目前测量船船体变形测量系统的一些不足,首次提出采用双频偏振法测量横扭角,并从实际出发介绍了双频偏振辐射源产生的三种方法。在着重分析该方法的测量精度后,讨论了双频偏振法的优越性及不足之处。     

轴承预紧力测试装置的研制

自行研制了轴承预紧力测试装置,该装置包括轴和轴承系统、加载装置、传感器和数据测量与采集系统.通过该装置可以精确测量出轴承实际所承受的轴向预紧力,还可以测量多种跨距下轴承预紧力.该测量装置提高了预紧力的测量精度,减小了劳动强度.     

基于矢量调制法的矢性物理量测量仪器

依据调制解调原理和线性系统理论，矢量调制法使用机械转动方法，将输入信号在进入传感器之前调制成为正弦波，由于线性传感器的频率保持性和叠加特性，对传感器输出信号解调，将得到准确的输入响应，由此去除常见的传感器偏置、偏置的漂移、干扰与噪声。基于矢量调制法原理，开发了一套使用矢量传感器构造的新原理测量仪器，并详细叙述了该仪器的物理实现方法和算法原理，对影响测量精度的主要因素给出量化分析结果。作为应用实例，说明了VMM测量仪器在寻北仪、三维矢性物理量测量中的原理和方法。理论分析和实验测量表明，矢量调制法物理意义明确，操作方便简单，抑制测量误差效果明显。VMM测量仪器显著地提高了矢性物理量的测量精度，可以广泛用于矢性物理量的精确测量。     

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...     

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.     

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.     

Fractional order nonsingular terminal sliding mode control for flexible spacecraft attitude tracking

This paper investigates a fractional terminal sliding mode control for flexible spacecraft attitude tracking in the presence of inertia uncertainties and extern...     

奥氏体不锈钢表面双辉等离子渗锆的动力学

利用双辉等离子渗金属技术在0Cr18Ni9Ti奥氏体不锈钢表面制备了一层均匀、致密、呈良好冶金结合的渗锆合金层,并对1 060℃下的渗锆动力学进行了研究。结果表明:随着距锆合金层表面距离的增加,锆元素的含量呈梯度递减,扩散系数逐渐减小,而扩散激活能逐步增大;在1 060℃采用双辉等离子技术渗锆时,渗锆合金层表层的空位密度为2.945×(1012~1013)cm-2,与相同温度下采用常规渗金属工艺相比,提高了1~2个数量级。     

气化炉三维扫描测量与数据处理

以德士古气化炉耐火砖的内壁蚀损检测设备为基础,对采集到的点云数据做了进一步处理.通过对数据的筛选和剔除,实现了数据点的平滑降噪细化和精简.然后利用点云对整、网格划分和分色显示等方法,最终完成了内壁腐蚀情况的三维建模.重点讨论了点云数据的预处理及后处理的方法,并根据内壁耐火砖的腐蚀阈值,提出了一种气化炉内壁腐蚀区域的识别与分割方法.对耐火砖的腐蚀分析、气化炉的生产与维修提供了可靠依据,并在工程应用中获得了一致认可.