电磁驱动微机械陀螺接口电路的研究

电磁驱动电容检测的力平衡微机械陀螺相对于压阻检测等方式的其他形式的微机械陀螺来说,具有高灵敏度及高精度的突出优点,但是其接口电路也比较复杂.这一接口电路从功能上可分为驱动电路和检测电路两个部分:驱动电路的主要功能是使微机械陀螺产生在驱动模态固有频率下的振幅稳定的正弦振动;检测电路的主要功能是拾取陀螺所产生的角速度信号....     

随机相位抖动测量

无线电信号的重要特性之一是相位,为了澄清信号的相位特性的概念,提出了在工程系统里信号的相位特性,尤其是随机相位抖动的概念和表征。本文论述有随机相位抖动的测量方法,着重介绍一种为连续波雷达测试相位特性的相位抖动测试仪。详细分析该测试仪的设计细节和有关电路,该测试仪,经使用和系统自检,对5MHz～80MHz 信号测试,系统的相位漂移小于0.2°/小时,随机相位误差优于0.2°/10ms 和0.2°/1s。     

静电悬浮加速度计电容检测电路变压器桥路设计

静电悬浮加速度计用于测量非惯性力,是重力卫星的重要载荷,高精度重力场模型的获取对加速度计的分辨率要求很高。电容检测电路是加速度计的核心电路之一,其作用是通过测量差动电容的变化,反映检测质量块微小位移的变化,电容检测电路的噪声水平直接影响加速度计的分辨率。通过对电容检测电路的噪声分析,设计了变压器桥路,降低电容检测电路噪声。结果表明,变压器桥路输出阻抗越大,电容检测电路输出噪声越小,选取典型参数代入桥路输出阻抗公式进行仿真。当桥路谐振频率与电容检测信号工作频率相等时,输出阻抗达到最大。因此桥路设计所选取的参数,应满足使桥路谐振频率与电容检测信号工作频率相等,电容检测电路噪声能够大幅度降低。     

基于峰值检测的MEMS器件微弱电容检测电路

针对MEMS器件研制中微弱信号的检测问题,提出了一种适用于电容式MEMS器件的微弱电容检测电路.此电路采用峰值检测技术,原理及结构简单;只检测待测电容的变化量,既可用于差分式检测,也可应用于单一待测电容的情况.首先利用正弦载波信号和微分电路对电容量进行载波调制,再通过减法电路得到幅值与电容变化量成比例的正弦信号,最后采用峰值检测方法解调信号,得到直流量输出.利用微小可调电容进行标定,结果表明检测电路的线性度良好,灵敏度约为3.631V/pF,精度达到0.2%.利用该检测电路检测MEMS陀螺上振动频率为2.85kHz的梳齿驱动器的电容量变化,输出信号频率为（2.85±0.02）kHz,误差低于0.7%,说明该电路能够应用于MEMS器件的微弱电容检测.     

MEMS陀螺六阶连续带通多反馈∑△M闭环控制系统

设计了一种用于MEMS陀螺敏感模态的六阶连续带通多反馈∑△M闭环控制系统,以及相应的系统参数多目标优化方法．与以往的低通∑△M闭环控制系统相比,该系统不仅具有更好的噪声整形特征,能较大程度抑制陀螺噪声,而且易于在PCB电路上实现．由于整个闭环系统非常复杂且非线度较高,采用遗传算法对系统参数进行了多目标优化．系统优化之后的仿真结果显示,当输入角速度为200°／8时,在64Hz带宽范围内陀螺信号的信噪比可大于90dB,底噪为-120dBV／／Hz．最后采用常压封装的z轴全对称解耦结构的绝缘体上硅陀螺在PCB电路上进行了系统功能验证,测试结果显示系统具有明显的带通噪声整形特征,陀螺底噪为-100dBV／Hm．     

信号检测通道增益波动对IFOG影响

本文基于数字闭环IFOG工作原理、详细分析了信号检测通道的增益波动对陀螺的影响,指出在角速度动态变化的系统里．信号检测通道增益波动将成为不可忽略的因素：     

硅微机械陀螺的差分电容信号处理技术

本文针对电容式微机械陀螺的接口电路设计、闭环驱动、微弱信号检测和处理等问题开展研究。在充分满足陀螺本身工作需要的甚础上设计并实现了它的接口电路。同时进行了初步的实验分析。得到的结果显示它基本完成了驱动陀螺并且解调检测陀螺信号的功能,并且取得了测试结果。     

基于MSP430的高精度转台角速率校准系统设计

依据GJB1801-1993《惯性技术测试设备主要性能测试方法》设计了一套基于MSP430单片机的高精度转台角速率校准系统,实现了对速率转台的高精度角速率测量校准并给出了测试实例。该系统采用定时测角法,用高精度恒温温补晶振作为时间基准时钟,单片机控制正交解码芯片HCTL-2032对圆光栅传感器输出正交信号进行解码计数,同时设计了硬件周期同步电路保证了系统的等精度测量,最后由上位机应用软件做数据处理并显示、存储、报表打印。校准结果表明：在北京长城计量测试技术研究所超低速转速标准装置上进行角速率（0.001°/s~600°/s）校准,结果最高精度在360°间隔达到3×10-7。     

旋转飞行体横滚角高精度测量研究

利用我国自行研制的低漂移角速率陀螺敏感飞行体旋转角速率,其输出送给积分器进行积分运算,并由地磁方位变换器给出积分归零信号,消除了积分积累误差。在旋转角速率≤1080°/s条件下,工作时间1.5～4min,实测横滚角精度优于万分之一,可达十万分之四(工作时间99s测试结果)。     

振弦式硅微机械陀螺

提出了一种新的振弦式硅微机械陀螺的设计方案,这一陀螺的制作采用硅微机械工艺.一方面,陀螺驱动模块采用电磁力驱动,这样能极大地提高驱动幅度;另一方面,陀螺检测模块采用差分的双振弦方式,从而提高了检测精度.通过陀螺检测模块的振弦将角速度的变化直接转换成输出信号的频率变化,这样能够极大地提高信号的抗干扰能力.理论分析表明,这...     

Insertion of triangulated surfaces into a meccano tetrahedral discretization by means of mesh refinement and optimization procedures

In this paper, we present a new method for inserting several triangulated surfaces into an existing tetrahedral mesh generated by the meccano method. The result is a conformal mesh where each inserted surface is approximated by a set of faces of the final tetrahedral mesh. First, the tetrahedral mesh is refined around the inserted surfaces to capture their geometric features. Second, each immersed surface is approximated by a set of faces from the tetrahedral mesh. Third, following a novel approach, the nodes of the approximated surfaces are mapped to the corresponding immersed surface. Fourth, we untangle and smooth the mesh by optimizing a regularized shape distortion measure for tetrahedral elements in which we move all the nodes of the mesh, restricting the movement of the edge and surface nodes along the corresponding entity they belong to. The refining process allows approximating the immersed surface for any initial meccano tetrahedral mesh. Moreover, the proposed projection method avoids computational expensive geometric projections. Finally, the applied simultaneous untangling and smoothing process delivers a high‐quality mesh and ensures that the immersed surfaces are interpolated. Several examples are presented to assess the properties of the proposed method.     

Certification Institutions Expected to Update and Transfer Information on Present Standards

Standards are the basis for production enterprises to organize production, ex-factory inspection, trade (delivery) and technical exchanges, product certification, quality arbitration and supervision.……     

From Industry 4.0 to Research 4.0. Development of High Performance Fibers in the Light of Digitization

We associate a variety of innovations with the term ＂Industry 4.0＂. The pioneer of many 4.0 modifications forms the basisfor the trend towards the integrated di...     

Flow calorimeter for enthalpy increment measurements on condensed gases

A flow calorimeter for enthalpy increment measurements on condensed gases is presented. A better knowledge of the properties of the liquefied natural gas is needed, and therefore a liquid loop has been designed for our flow calorimeter. The fluid loop in the calorimeter is designed in order to avoid the two-phase region, since two phases would give compositional disturbances in the measurements. The avoidance of the two-phase region is made possible by increasing the pressure of the test fluid after the measurement section, then heating the fluid at super-critical pressure past the critical point. Finally, the fluid is throttled to the low-pressure gas state at the inlet condition of the compressor that circulates the fluid. To perform the pressure increase, a new cryogenic pump has been designed. To evaluate the new equipment, measurements were taken on liquid ethane over the temperature range 146–256 K at pressure between 0.9 and 5.1 MPa.     

Refrigerators Enter a New Era of Health Preservation Frestech initiates the establishment of China's first standard for household sterilization refrigerators

On November 30, 2007, the China Association for Standardization (CAS) held a press conference at Beijing Diaoyutai State Guest House. Leaders from the China Household Electric Appliance Research Institute, the China Household Electric Appliance Association, and the China Consumers' Association attended and made speeches.……     

Optimum-Simulation von Ernteprozessen

Zusammenfassung Bei der Gestaltung von Ernteprozessen — beispielsweise des Prozesses Mähdrusch, Körnertransport und -abnahme — als transportverbundene Fließarbeitsverfahren mit mindestens zwei verschiedenen Arbeitsmitteln gibt es einen großen Optimierungsspielraum. Solche Prozesse sind mehrstufige Bedienungsprozesse mit gemischter Anordnung der Bedienungseinrichtungen. Außerdem besitzen sie stark ausgeprägte räumliche Aspekte. Es wird vor allem gezeigt, welche Merkmale solcher Prozesse in Simulationsmodellen abgebildet sein müssen, welche Zielgrößen in Abhängigkeit von welchen Einflußgrößen unter Berücksichtigung welcher Prozeßbedingungen ermittelt werden sollten und wie der Bewertungsprozeß zur Ermittlung der gewünschten Informationen gestaltet werden muß.     

Roman iron and steel: A review

ABSTRACT

The production of ferrous metal increased during the Roman Late Republican period, Principate and Empire. The direct bloomery process was used to extract the metal from its ores using slag-tapping and slag-pit furnaces. The fuel was charcoal and an air blast was introduced by bellows-operated tuyères. Iron formed as a bloom, often as a spongy mass of metal, which contained impurities from the smelting process, including unreacted ore, fuel, slag and fragments from the furnace walls, while the metal was often inhomogeneous with varied carbon contents. Blooms were either smithed directly into bars or ingots or they were broken up, which also allowed the removal of gross impurities and a selection of pieces with similar properties to be made. These could then be forge-welded together and formed into characteristically shaped ingots. Making steel in the furnace seems to have been achieved: it depended on the ore and the furnace and conditions within it. Surface carburization was also carried out. Iron and steel were used extensively in construction and for tools and weapons. Fire welding was often used to add pieces of steel to make the edges of tools and weapons, which could be heat-treated by quenching to harden them.     

A study of centrifugal cast high boron high speed steel

In the present study a high‐boron high speed steel (HSS) roll material was designed. Many expensive alloy elements have been substituted by cheap boron alloy, and high‐boron high speed steel roll has been manufactured by centrifugal casting method. The microstructures, mechanical properties and wear resistance of centrifugal casting high‐boron high speed steel roll have been investigated by optical microscopy (OM), scanning electron microscopy (SEM), and X‐ray diffraction (XRD) analysis, hardness test, impact test and wear test. The results indicated that the solidification microstructures of high‐boron high speed steel roll consisted of M₂(B,C), (W,Mo)₂(B,C), M₃(B,C), M₂₃(B,C)₆ type borocarbides and martensite, a small amount of retained austenite. Borocarbides were continuously distributed over the grain boundary. After quenching from 1050 °C, local broken network appeared in partial borocarbides, and fine secondary borocarbide precipitated from the matrix. After tempering from 525 °C, the amount of precipitated borocarbide increased significantly. After heat treatment, the hardness of high‐boron high speed steel roll excelled 60 HRC, and its impact toughness excelled 8.0 J/cm². The single groove steel rolling amount of high‐boron high speed steel rolls increases by 500% than that of bainite cast iron roll, when the rolls are used in K₁ mill housing of bar mill.     

Thixotropy of Systems with Shear Thinning and Plastic Flow Behavior

The definition of the thixotropy is a decrease in viscosity with time in shear and a subsequent recovery of viscosity after the shear deformation is removed.We ...