热电式MEMS微波功率传感器结构优化的研究

为了改善热电式微电子机械系统(MEMS)微波功率传感器的综合性能,研究了负载电阻与热电堆的间距、衬底背面刻蚀的厚度、长度以及热偶长度4个结构参数,将传感器分成3个区域讨论,建立了热电式MEMS微波功率传感器的灵敏度解析模型。此外,还研究了热电式MEMS微波功率传感器的时间常数模型,传感器的时间常数由负载电阻和热电堆的时间常数组成。最后,根据理论模型分析得出当减小负载电阻与热电堆的间距、增加背面刻蚀厚度、长度以及热偶长度为400μm时,能在保持较小的时间常数的情况下提高灵敏度,从而改善热电式MEMS微波功率传感器的综合性能,这对热电式MEMS微波功率传感器的结构参数的设计与优化具有一定的参考价值和指导意义。     

热电式MEMS微波功率传感器模型的研究

为了提高热电式微机电系统(MEMS)微波功率传感器的灵敏度特性,建立了噪声系数、时间常数和灵敏度的理论解析模型。根据理论解析模型,分析得到了影响噪声系数、时间常数的首要因素、次要因素;然后,探究了噪声系数和时间常数对灵敏度特性的制约;最终,发现制约热电式MEMS微波功率传感器灵敏度特性的两个关键结构参数:热电偶的长度和数目。依据所建立的理论解析模型,设计了一种渐变结构的热电式MEMS微波功率传感器,实验表明该传感器在8~12 GHz频率范围的回波损耗在-22~-19 dB,具有较好的匹配特性。系统灵敏度分别为0.23 mV/mW@8 GHz、0.22 mV/mW@10 GHz、0.21 mV/mW@12 GHz,较与传统结构的灵敏度特性有了较大改善。因此,所建立的噪声系数、时间常数和灵敏度的理论解析模型对于研究热电式MEMS微波功率传感器具有一定的参考价值和指导意义。     

铜-康铜热电偶的锡膜焊接及热电特性

提出一种制作铜 -康铜热电偶的新方法 :锡膜焊接法。既保证了焊接设备价格低廉 ,又避免了热电偶出现沾污、脆断等缺陷。利用此法制作的热电偶 ,各热电偶的一致性好 ,在 - 40～10 0℃温度范围内 ,与标准热电偶的热电特性吻合得很好 ,其精度达到± 0 .1℃ ,可作为二级标准温度计使用     

用热电偶测温应注意的问题

热电偶是一种普遍使用的测温传感器。由于它结构简单,几何尺寸很小,测量精度高,测试又很方便,所以在机床行业中常用于机床温度场、热源、切削温度的测定。 对于精密机床试验来说,其测温精度有一定要求。因此,在利用热电偶(如铜-康铜热电偶)进行测温时,首先要对热电偶进行标定,画出热电势-温度对应关系的定标曲线。然后才把热电偶粘贴在机床上的被测温度点。当机床运转一段时间后,就能测到因温度上升而产生的热电势值,再查定标曲线,读得所对应的温度值。可见定标曲线是否正确将直接影响着测温精度。 常用热电偶定标,就是利用一只标准水银计作…     

基于NANMAC热电偶的时间常数测试技术研究

本文介绍了热电偶时间常数的测试理论,提出了运用瞬态表面温度传感器动态校准系统实现对NANMAC热电偶时间常数的测试方法。该系统对红外探测器和热电偶进行了静态校准和动态校准,得到两者的温度一时间曲线。由于红外探测器的频率响应优于被校准热电偶的频率响应,因此,以红外探测器测得的值作为真值,用热电偶测得的值与红外探测器测得的值相比得到-条归-化的曲线,并由归-化曲线求得热电偶的时间常数。利用该方法对NANMAC热电偶进行时间常数的测试实验,得到了该热电偶的时间常数。实验结果表明：该时间常数测试方法是可行的,可以实现对微秒、毫秒量级热电偶的动态校准,这对于NANMAC热电偶温度传感器的研究和应用具有一定的参考价值。     

基于单片式微波集成电路的终端式MEMS微波功率传感器(英文)

提出了一种基于塞贝克效应的终端式MEMS微波功率传感器,该传感器的制作工艺与GaAs单片式微波集成电路(MMIC)工艺兼容.利用热电偶检测温度差,生成与微波功率成比例的直流电压,由GaAs/Au热电偶串联构成热堆.传感器将电功率转化为热,再间接测量热堆生成的直流电压.采用微机械加工技术,去除了器件底部的GaAs衬底,从而减小了热损耗和电磁损耗,提高了灵敏度.测试结果表明,在0～20 GHz内,HFSS模拟的S11＜-22 dB;测试输入功率为-20～20 dBm时,频率为0～20 GHz;在20 GHz时,灵敏度高于0.15 mV/mW;在整个频率范围内,回波损耗低于-26 dB.     

钻削快停装置的标定

本文用理论分析的方法推导出钻屑根部取样误差与钻削怏停装置时间常数的关系。采用专门高频响压电晶体力传感器测得钻削怏停装置时间常数为6×10~(-5)秒。     

高温压力传感器温度特性的芯片内补偿技术

本文在分析、测试多晶硅高温压力传感器温度特性的基础上 ,提出了一种新的改善传感器温度特性的措施。通过在压力传感器芯片上集成低阻值的多晶硅电阻网络与温度传感器 ,不仅可以很好的补偿传感器的零点温漂 ,也可以借助传感器信号处理单元 ,方便地实现对灵敏度温度系数的补偿。经补偿 ,传感器的零点温漂达到 1× 10 -4/℃ ,灵敏度温漂小于 -2× 10 -4/℃。实验表明 :该方法的补偿温区宽 ,通用性强 ,是高温压力传感器十分有效的温度补偿方法     

气动传感器在对称度误差检测上的应用

<正> 前言将微位移或微间距等物理量转换成气动参量(压力P、流量Q)的元件称谓气动传感器。通常这些微量是用机械式量具来检测的,但测量精度不高,当采用气动传感器作为探头,并组成一套气动测量系统(方框图见图1)后,可以实现精密测量,实验表明,气动传感器能够分辨0.1μ的位移量。气动测量仅有几十年的发展史。它由低压式[测量介质空气的压力为(0.03～0.12)×10~5P_a]测量发展到高压式[(0.5～3.5)×10~5P_a]测量;由单参数测量发展到多参数测量;由静态测量发展到动态测量;由单一的气动量仪发展到气动与机械、光学、电     

莴苣组织传感器的研究

选用莴苣组织切片作为生物催化材料,与二氧化碳气敏电极组合,研制成对L-组氨酸有选择性响应的新型组织传感器.传感器的线性范围为1.0×10~(-4)～1.0×10~(-3)mol·dm~(-3),检测下限为3.2×10~(-5)mol·dm~(-3),斜率为54.2mV/dec.初步探讨了组织膜中酶促反应的动力学机理.测定了L-组氨酸脱羧酶的动力学参数K_m和V_m.     

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.