应用于谐振式光学陀螺的正弦波调制解调技术

谐振式光学陀螺(ROG)是一种基于光学Sagnac效应检测转动角速度的高精度惯性传感器。锯齿波和三角波调制会导致谐振信号出现大量毛刺噪声以及复位脉冲的问题,通过正弦波调制解调可以解决上述问题,而且具有更高调制频率的优势。搭建了光学微谐振腔调制解调实验系统,分析了正弦波调制参数的变化对谐振曲线与鉴频曲线的影响。在调制频率为4 MHz,调制幅值为2 V时,得到了最为平滑的谐振曲线与最佳线性度的鉴频曲线。为光学微谐振腔在谐振式陀螺系统应用中相位调制选择最佳的参数提供了参考。     

石英音叉三维谐振触发定位系统

为实现对微器件等三维测量时在三维方向上任意单点的高精度触发定位,提出一种新型三维谐振触发定位系统.以石英音叉作为微力传感器,与一体式光纤微测杆测球相结合,利用其谐振参数(谐振振幅、谐振频率/谐振相位)对微力的高敏感性构建三维谐振触发测头.将该测头与三维纳米定位台、反馈控制模块、信号处理电路结合,分别构成完整的振幅反馈和相位反馈三维谐振触发定位系统.工作时驱动石英音叉测头处于谐振状态,检测顶端测球与试样表面接触微力引起的振幅变化或频率变化.测头顶端测球与试样表面在Z向以轻敲模式接触,在X、Y向以摩擦模式接触.实验结果显示:系统在X、Y、Z3个方向的触发分辨力分别达到0.17 nm、0.20 nm、0.18 nm;三维重复性误差分别达到37.0 nm、70.6 nm、41.0 nm.实验结果验证了提出的三维谐振触发定位系统纳米量级精确定位的可行性和有效性.     

一种用于微谐振器频率调节的静电梳齿结构设计

针对微梳齿谐振器频率偏移的问题,提出了一种用于微谐振器频率调节的曲线形状静电梳齿结构。通过对梳齿简单模型的静电力分析,得出其静电力-位移特性,其斜率就是静电弹性系数;然后从谐振频率出发,分析了影响谐振频率的因素。研究结果表明,对于梳齿式微谐振器,当调谐电压从0 V变化到80 V左右时,器件的有效弹性系数从2.64 N/m减小到1.23 N/m左右,且谐振频率从自然谐振频率18.9 kHz减小到13 kHz,降幅分别为53%和31%。实验结果表明,这种曲线梳齿"软化"了静电微谐振器或者微驱动器的系统弹性,能够有效地调节谐振频率。     

一种微机械谐振式加速度计的自激驱动控制

为了研制谐振微机械加速度计,文中介绍了静电刚度的谐振式微加速度计的工作原理,并根据闭环控制要求,建立了基于自激原理的系统分析方程,利用平均周期法分析了系统稳定性和振动幅度稳态平衡点。理论分析确定了系统起振条件和相位偏差对闭环振幅和频率的影响。对基于体硅溶片制造和真空封装的谐振微加速度计,自激闭环测试结果表明检测电压1 V时,灵敏度为18 Hz/g;检测电压5 V时,灵敏度为58 Hz/g,10 min内闭环谐振频率最大漂移0.2 Hz,可分辨加速度约3.5 mg.     

基于矩形贴片天线的应变传感器模拟与测试

当贴片天线经历应变时,天线形状发生改变,导致其谐振频率发生偏移。基于此原理,提出采用矩形贴片天线的应变传感器测量结构中的应变。采用了2.4GHz的1/4波长矩形贴片天线作为应变传感单元,首先,利用HFSS~(TM)软件设计应变传感器的尺寸参数,分别模拟该天线在长度与宽度方向经历拉应变时的谐振频率偏移;其次,分别将贴片天线以纵向、横向的方式粘贴在铝板上进行了受拉实验;最后,利用网络分析仪获得天线的谐振频率。模拟与测试结果表明,天线的谐振频率偏移与天线长度方向上的应变具有良好的线性关系,同时,天线宽度方向上的应变对其谐振频率的影响较小。     

基于腔结构的射频微机械谐振元件的设计

对圆柱形复合腔结构微机械谐振元件进行了设计研究,提出了一种基于柱形腔结构的微机械复合谐振元件的设计方法,并对其结构及特性进行了研究.建立了复合腔结构的电磁场数学方程,腔体基于体微机械微细加工技术实现工艺设计,最后对该元件进行了仿真分析.TM010模式下,谐振腔谐振频率为24.313299GHz,Q值为3529.707890,考虑微带耦合时仿真出复合谐振元件的最佳谐振频率为24.75GHz.仿真实验结果和理论值的平均误差不到1%,两者吻合得很好,说明了该设计的可行性.进一步改变结构参数,可获取不同谐振频率的器件,且可在腔体中填充高介电常数介质来减小器件的谐振频率,克服了以往使用腔体结构在低频段时体积过大等问题.     

基于ZnO压电薄膜的柔性声表面波器件

提出并制备了基于聚酰亚胺柔性衬底的声表面波(SAW)器件。在柔性聚酰亚胺衬底上低温反应磁控溅射沉积了ZnO压电薄膜;采用X射线衍射仪,扫描电子显微镜,原子力显微镜等设备对ZnO薄膜进行了检测,结果表明:ZnO薄膜晶粒呈柱状生长并且(002)择优取向,膜粗糙度小于9nm,适合制作压电器件。在柔性衬底上制备了基于ZnO压电薄膜的SAW器件,该器件表现出良好的谐振性能。采用矢量网络分析仪检测器件的传输曲线,实验结果与仿真结果具有很好的一致性。随着波长减小,谐振频率和相速度增加,当ZnO厚度为4μm,波长为8μm时,器件的谐振频率为268MHz,相速度为2 144m/s,机电耦合系数为1.1%;当ZnO厚度增加时,此叠层结构的声表面器件的叠层声速也增加。     

谐振面积与电极图案对质量传感器性能的影响

在p型(100)单晶Si基衬底上,利用磁控溅射设备完成直流溅射Mo/Ti布拉格反射层和射频反应溅射AlN压电层,用光刻微加工工艺设计了不同谐振面积与电极图案的Ti/Au上电极,在优化工艺条件下制备了氮化铝基体声波质量传感器,比较分析了不同电极图案和谐振面积对传感器性能的影响。研究表明,电极图案相同时,谐振面积为10 000(100×100)μm2的器件电学性能最好,谐振面积相同时,电极图案为圆形的损耗最小;内角为直角的正方形损耗最大,内角为钝角的五边形损耗居中。     

独特谐振模式下薄膜体声波谐振器的设计

计算了四层复合结构的薄膜体声波谐振器(FBAR)的输入阻抗谱,各层采用的材料分别是Al/AlN/Al/Si,其尺寸为0.8 μm/1.9 μm/0.8 μm/100 μm,得出其有效机电耦合系数k²_eff随谐振模式的分布情况,从而得到最大k²_eff的独特谐振模式在1~2 GHz为第40阶谐振模式。从理论上探讨了各层的尺寸及材料属性对该独特谐振模式及其频移的影响,以及串联谐振品质因数FOM等滤波器设计的主要性能参数在该模式下的分布情况。实验结果表明,工作在独特谐振模式下的FBAR的性能依赖于各层材料尺寸,当压电层厚度从0.2 μm变到4.3 μm时,特殊谐振模式频率从1.2 GHz增加到4.8 GHz;当基底厚度变厚时,有效机电耦合系数从3.2%变到0.8%,串联品质因数从2 000变到700;而电极变厚后,有效机电耦合系数趋于一个稳定值。这些数据在实际设计过程中对滤波器的微调具有参考意义。     

基于ADAMS的系统结构谐振频率分析

虚拟样机技术是集工程设计技术、建模仿真技术与可视化技术等多学科于一体的综合性技术,文中主要介绍了在虚拟样机仿真软件ADAMS中天线系统的样机模型建立方法,并在考虑齿轮非线性因素时,应用动力学仿真软件ADAMS对天线系统的结构谐振频率进行仿真计算,实现结构优化设计。     

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.