基于双反馈模式的大范围自感应AFM测量系统

为了提高原子力显微镜（AFM）的测量范围,设计了一种基于双反馈测量模式的大范围自感应原子力显微镜系统,测量系统中有两条反馈回路:一条反馈回路由压电陶瓷与AFM测头组成,动态响应较快的压电陶瓷位移台的运动量可以表征被测样品表面的高频信息;另一条反馈回路由压电陶瓷位移台和纳米测量机（NMM）的反馈控制器组成,利用压电陶瓷位移台的位移信号控制NMM运动,NMM的mm级z向测量范围使得被测样品较大变化范围的低频轮廓信息很容易地被表征出来。使用本系统对平面样品和一维栅格进行了测量实验,实验结果表明采用双反馈的测量模式的AFM测量系统能够有效地表征被测样品的低频轮廓信息和表面高频信息,测量范围能够达到mm级,纵向分辨率达到nm级,具有良好测量重复性。     

优化型多扫描方式原子力显微镜的研制

本文提出和发展了一种多扫描方式的新型原子力显微镜(AFM)技术及系统。该系统拥有三个不同的扫描器,以相互组合的方式实现三种不同的扫描方式,由管状压电陶瓷驱动的柔性结构扫描器,采用样品扫描方式,对于小尺寸样品能够提供高分辨率的快速扫描;由叠层式压电陶瓷驱动的扫描器,采用探针扫描方式,提供各类样品的大范围扫描;由步进电机驱动的扫描器,采用样品扫描方式,能够实现大尺寸样品的大范围扫描。三种方式的单幅图像扫描范围可分别达到4μm×4μm、20μm×20μm、40μm×40μm。实验结果表明,借助于上述多扫描方式及独特的结构设计,该 AFM 不仅具有分辨率高、扫描速度快、重复性好等优化性能,而且能同时实现各类尺寸样品的各种扫描范围的微纳米成像,具有更好的实用性,可望在微纳米技术领域获得广泛应用。     

基于VB的纳米级驱动控制系统研究

压电陶瓷拨爪电机具有大行程、高速、位移分辨率高等突出优点,可以避免使用传统的二级驱动,直接实现纳米级驱动定位.利用PCI-7484数据采集卡和FAGOR自反馈光栅数显卡提供的DLL动态连接库函数及VB中的Timer控件,实现了对压电陶瓷拨爪电机的实时可编程控制以及位移信号的获取,成功地构建了纳米级驱动控制系统.经测试,该系统的位移分辨率可达10 nm.     

新型纳米分辨率位移定位平移台的研制

为克服已有压电驱动器存在的结构及控制系统复杂、定位行程小等缺陷,利用压电陶瓷的逆压电效应设计并制作了一种新型的压电纳米步进驱动器,建立光栅测试系统对这种压电驱动器的动态性能进行了测试.将压电纳米步进驱动器与电磁伺服马达耦合,设计新颖驱动结构,利用微机通过步进运动控制卡统一控制,实现大范围一维纳米分辨率位移定位.系统样机解决了所研制压电纳米步进驱动器双向运动、实用定位等问题.位移定位分辨率为50 nm,定位行程为100mm,纳米分辨率定位最大速度为0.6 mm/s.     

压电陶瓷电机在数控齿轮测量仪器中的应用

简要介绍压电陶瓷电机的工作原理及性能，分析了压电陶瓷电机用于数控齿轮测量仪器上的优缺点，通过实际应用验证了压电陶瓷电机可以作为直线驱动系统用于齿轮测量仪器中。     

基于纳米运动平台的原子力显微镜开发

采用一种无耦合、三轴精确定位的纳米运动平台作为扫描器,研制了一种新型原子力显微镜(AFM).该AFM有效消除了通常使用的单管式压电陶瓷扫描器扫描过程中运动耦合产生的两种结构误差--交叉耦合误差和扫描范围误差,极大提高了纳米测量及操作的精度.     

纳米光栅动静态校准工作台

为了改善纳米光栅校准装置校准精度、校准量程及动态频响难以兼顾的问题,采用宏微运动控制方法驱动校准装置作快速、精密、大范围运动。宏动平台由静压气浮导轨和直线电机组合而成,微动平台由柔性铰链和压电陶瓷构成。对宏动平台和微动平台进行动力学建模,并获得宏微运动平台的传递函数。设计微动跟随宏动和宏动跟随微动两种控制策略,并进行建模和仿真分析,利用搭建的实验平台进行了校准装置的性能测试。实验结果表明:宏动跟随微动控制策略具有较高的动态频响性能,校准装置在全行程20 mm内分辨力达到5 nm;在幅值为0.05 mm的正弦频率响应实验中,动态频响达到100 Hz,可满足纳米光栅的动静态校准要求。     

基于弯曲模态的板形直线超声电机结构设计

板形直线超声电机因具有扁平化结构等特点,特别适用于电机安置空间狭窄的直线驱动场合。针对狭窄空间作动需求,提出一种单模态、大推力直线超声电机。电机由导轨和板形定子组成,定子由平面内两个垂直放置的矩形板联接构成L形结构,驱动足位于联接部顶端。电机利用两矩形板弯曲振动所形成的对称和反对称模态驱动导轨运动,并通过切换对称和反对称模态实现导轨正反向运动。通过定子模态分析,研究结构参数对振型的影响,以确定夹持和压电陶瓷片的安置位置;针对对称模态下驱动足处振幅过小问题,分析前端盖开槽对驱动足处振幅的影响规律,并通过开圆弧形槽增加驱动足处振幅。制作样机,并开展实验研究。实验表明:该电机结构简单紧凑、运行稳定且推力大,最大空载速度为329 mm/s,最大推力为70 N,推重比达38. 2。     

高线性度的二维无耦合纳米压电位移系统设计

设计了一套具有高线性度的二维无耦合纳米压电位移系统。提出了一种多个压电陶瓷同步线性操作的电荷控制方案,设计采用基于非线性反馈控制和相似控制相结合的具有接地配置功能的压电控制器。控制器中引入了T型电阻网络,使电容较小的压电致动器能够进行低频线性操作。并对压电陶瓷驱动的位移平台进行了机械结构设计,平台采用嵌套式串联结构来避免耦合位移。通过解析法和ANSYS Workbench有限元仿真两方面对位移平台进行了刚度及位移分析。搭建了一套干涉位移测量系统,对压电位移台的位移、耦合误差及线性度进行了验证测试。实验结果表明:系统满行程内二维位移台的耦合误差最大仅为0.098%,可以将迟滞不对称引起的剩余轨迹偏差减小到0.79%,两个压电陶瓷间的最大轨迹偏差仅为行程范围的0.23%,理论分析和实验验证了所设计多压电电荷控制器的可行性,且系统可有效抑制耦合位移并使定位精度得到明显提高。     

多自由度压电纳米定位平台控制技术研究现状

介绍了压电驱动的工作原理、压电材料的非线性特性以及压电定位平台的直接驱动方式,分别阐述了串联、并联和串并联三种驱动方案的多自由度压电定位平台的结构设计以及解耦优化方式。重点分析了多自由度纳米压电定位平台控制系统需要解决的压电驱动器的非线性特性、交叉耦合等问题,提出应根据多自由度压电定位平台不同的结构和运动形式选定合适的控制策略。最后总结了适用于多自由度压电定位平台的控制算法,有助于研究者了解压电纳米定位平台领域的最新进展,为压电纳米定位平台控制技术研究提供借鉴。     

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.……     

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.     

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...     

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 ...