一种抑制低频噪声的微机械陀螺C／V转换电路

目前一般均采用电荷放大器作为微机械陀螺前置接口电路,实现电容变化信号C／V转换提取。文章设计了一种能够抑制低频噪声的微机械陀螺前置C／V转换电路,分析了低噪声前置C／V转换电路的工作原理,用Saber软件对传统电荷放大器和低噪声前置C／V转换电路从时域及频域方面进行了仿真对比,最后通过实验验证仿真结果的可靠性。仿真及实验结果表明,设计的前置C／V转换电路能更好地抑制低频噪声。     

硅微陀螺机械热噪声研究

振动式硅微陀螺仪要在各种噪声干扰下,检测出极其微弱的有用信号.随着硅微陀螺性能的不断提高,机械热噪声对微陀螺的影响愈加显著,决定了振动式硅微陀螺的极限分辨率.本文给出了机械热噪声的产生机理,推导得出机械热噪声等效角速率表达式.分析表明,提高微陀螺的品质因数、增大质量和谐振频率可减小机械热噪声.     

铯光泵磁力仪光电检测电路噪声特性研究

光电检测电路噪声性能是影响磁力仪灵敏度的重要因素。基于M_x型铯光泵磁力仪光电信号的特点,对磁力仪光电检测电路噪声来源进行分析,建立了基于跨阻放大电路的等效噪声模型,推导出电路信噪比及输出噪声频谱特性,并分析各噪声分量在总噪声中的比重;根据磁力仪拉莫尔信号频带范围,设计研制了具有低噪声性能的光电检测电路并应用于铯光泵磁力仪。测试结果表明,所提噪声模型理论分析和实验结果一致,基于跨阻放大的光电检测电路,其低频段噪声主要由等效电流噪声决定,随着频率升高,放大器等效电压噪声逐渐起主要作用。进一步的野外实验表明,基于光电检测电路所研制的光泵磁力仪噪声达0.6 pT/√Hz,与国外同类产品CS-VL水平相当。     

静电悬浮转子微陀螺微位移信号检测系统的设计

为实现对悬浮转子微陀螺转子五自由度的测量,提出了一种频分复用的微位移检测原理,主要介绍了多频率信号发生器,前置放大器,锁相放大器组成的测试系统,设计了一种基于DDS技术的多频率信号发生器和基于锁相放大原理的解调电路。实验和分析结果表明,该电路能实现多自由度微位移检测,设计的多频率信号发生器的频率分辨率能达到0．005821Hz,相位分辨率可以达到0．006rad,检测轴向灵敏度为1．34V／μm,检测径向灵敏度为0．092V／μm,测量电路的轴向位移分辨率为0．45nm,径向位移分辨率为6．6nm,转角的分辨率为0．25μrad,位移检测电路的分辨率,灵敏度和测量范围能够满足静电悬浮转子微陀螺的控制需要。     

电容式微机械惯性传感器信号检测技术研究

针对具有差分电容接口的微机械惯性传感器提出了一种基于电荷放大器和相关检测技术的接口电路方案.采用电荷放大器作为电容-电压转换电路,来去除传感器本身以及传输导线引起的寄生电容的干扰.利用PSPICE模拟了桥路的不对称性对电路输出的影响,经过比较采用单载波差分电桥结构以进一步增大电容检测的灵敏度.采用相关检测技术进行解调,通过解调电路对前置输出电压和载波信号进行相关运算从而消除电路的宽频噪声;给出了包括布线、接地、去耦等电路工艺的设计原则.采用一组标定电容作为传感器的模型进行了实验,实验电路灵敏度可以达到195V/pF,最小分辨率为1fF.采用该方案能够满足对普通精度的电容式微机械惯性传感器信号的检测.     

电容检测型微机械陀螺的信号检测电路

微弱输出信号的检测技术是微机械陀螺研制中的关键技术之一.提出了一种适用于电容检测型微机械陀螺的信号检测电路并分析了其对噪声的抑制能力.此电路用积分电路检测微小电容变化量,并进一步采用开关相敏解调电路对信号全波检测,能检测到aF量级的电容变化,可以实现陀螺0.05(°)/s的分辨率.     

带温度补偿的低温漂石英微机械陀螺接口ASIC设计

本文通过分析石英陀螺的工作原理,设计了闭环自激驱动、低噪声相敏解调原理的接口电路,并研究了驱动力耦合对零位输出造成的影响,以提高石英陀螺的环境适应性。通过研究传感器敏感表头的空气阻尼和谐振频率等方面的温度特性,得出温度对驱动力幅值的影响。进而提出通过驱动力幅值进行温度补偿的方法。对接口电路温度特性以及对陀螺零位输出的影响进行了分析,设计了全温区带宽恒定的运算放大器单元,抑制由于检测信号中高次谐波分量比例变化产生的温度漂移,并在高压N阱CMOS工艺下流片,实现低温漂接口ASIC。在-45℃~85℃的温度范围内对石英陀螺整机进行零位温度循环测试,利用驱动力幅值对零位输出进行三阶拟合补偿,补偿后全温零位温度漂移小于20°/hr(1σ),短期稳定性为5°/hr,输出噪声为0.001°/s/√Hz。     

一种高性能电磁式微机械振动环陀螺

模态匹配和高的品质因数是提高振动环陀螺性能的关键。设计制作了一种电磁式微机械振动环陀螺,采用了全对称的结构以实现模态匹配。通过理论推导建立了陀螺灵敏度和机械噪声的数学模型,分析了陀螺参数对灵敏度及分辨力的影响。采用（100）晶向的单晶硅及MEMS体硅标准工艺加工了陀螺样片,该工艺简单,无需键合。器件频响实验结果表明,所设计的振动环陀螺驱动模态和检测模态频差小于0.5Hz,大气压下品质因数约为500,在1Pa的低真空下达到14000。锁相放大器测试结果表明,在-200 ~200 o/s测量范围内,陀螺分辨力为0.05o/s,灵敏度为0.2uv/ o/s。测试结果表明该陀螺能够实现模态匹配和较高的品质因数,具有较高的性能指标。     

低噪声尾纤光电探测模块结构设计

光电探测器模块噪声水平的高低在一定程度上影响着光纤陀螺的精度。本文设计了一种用于高精度光纤陀螺的尾纤探测器模块,由于其跨阻式反馈电路结构决定了噪声输出水平较高,通过更改模块探测器芯片接入前置放大电路的电气连接原理,在保证其它光电参数不变的前提下,在全温度范围内,其整体噪声输出降低了约30%。     

微机械振动环陀螺

为了减小振动环驱动模态和检测模态的频率差从而提高陀螺性能,提出了一种采用电磁驱动、电磁检测的全对称振动环陀螺结构。采用MEMS体硅工艺完成该微机械振动环陀螺的加工,其结构在保持镜像对称的同时,还保持了中心对称,因此整个结构高度对称,有利于减小模态频率差。为有效跟踪陀螺驱动模态的谐振频率并稳定驱动模态的幅值,设计了闭环驱动控制电路。该电路由低噪声前置放大器、相位调整环节以及自动增益放大器(VGA)组成。测试结果表明,该陀螺两个模态频率差为0.27 Hz,实现了频率较好的匹配。在±200 °/s,测得陀螺灵敏度为8.9 mV/(°/s),分辨力为0.05 °/s,非线性度为0.23%。     

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.     

ANGULAR DISTORTION ALLOWABLE VALUE AND ASSESS METHOD OF WELD ON COKE TOWER

A graph as the new engineering method for estimate the safety of bulging deformation of coke tower is proposed. Through stresses analysis of circumferential weld of coke tower and comparing the stresses produced by pressure with heat stress of steady state, residual stress, bending stress produced by both itself weight and wind loads, it showed that the stresses produced by pressure on the angle distortion are the main factor of equivalent stress of the combined stress. After comparing four kinds of stress controlling conditions, the relation to stress with depth of angular distortion, grade of curvature of angular distortion and half of region of angular distortion has been inferred. Graph of deformation allowable value of coke tower for different condition by angular distortion and half of region of angular distortion has been plotted. The five steps for its engineering use have been explained. The lighter the grade of curvature is, the larger of bulge allowance, may be, and the bigger of depth of angular distortion may pose too. For the coke tower with a popular structure of Dg 5 400 mm×28 mm, the result by graph is nearly more than the result of two formulas formed by other research, the error is less than 7.0%. But, the graph can be easily applied to different size of angular distortion.