共焦双光头多层数据存储系统

为了实现双光子多层数据存储系统的实用化,利用现有DVD高精度聚焦、循迹伺服技术,构建了共焦双光头多层数据读写系统,实现读写焦点在三维存储材料中的精确定位.同时由D/A输出选层信号控制音圈电机,实现了层间跳转,达到了多层读写之目的.本文通过建立光学头的音圈电机模型以及音圈电机控制器模型,实现对共焦双光头多层存储系统的建模与仿真,并给出已有的实验结果.     

飞秒激光三维微细加工技术

双光子吸收几率与光强度的平方成正比,因此,双光子吸收引发光致聚合局限在紧密聚焦的焦点区域,通过控制焦点的扫描运动可实现高精度三维加工。基于该原理,提出了一种利用飞秒激光进行微细加工的技术。根据此技术,建立了飞秒激光三维微细加工系统,该系统包括光源系统、显微镜系统、实时监测系统和精密移动系统等。研究发现,该系统加工的直线线宽最小可达500nm;加工线宽与加工速度成反比;激光功率为2mW时,最大和最小临界加工速度分别为80μm/s和1μm/s;制备出线宽1μm,宽度5μm的“CHINA”复杂结构,以及杆间距、层间距均为5μm的三维木堆型光子晶体结构。实验证实,该技术是一种非常灵活的微细加工技术。     

高频响应下音圈电机复杂迟滞特性建模与验证

为了实现音圈电机(Voice Coil Motor,VCM)在高频、高速、高加速情况下的精确定位控制,针对引起音圈电机产生振动、系统不稳定等问题的特殊复杂迟滞特性,建立了其复杂迟滞模型。改进了C-S迟滞模型,提出了C-S神经网络混合动态复杂迟滞模型;用音圈电机的两组实测数据验证了模型的有效性。实验结果为：音圈电机工作在低频、低速、低加速时(10Hz)表现出一般的迟滞特性,这时建模的最大误差为4.8μm,是最大输出值的0.48%,表明该方法能够有效的补偿音圈电机一般的迟滞特性;音圈电机工作在高频、高速、高加速时(40Hz)表现出特殊的复杂迟滞特性,其建模的最大误差为6μm,是最大输出值的0.97%。说明该方法能够满足复杂迟滞特性建模的要求。     

光针轮廓仪伺服机构设计与聚焦误差信号的改进

应用线切割方法设计了光针轮廓仪伺服机构一音圈电机的结构，使其具有更好的静动态特性和焦点自动跟踪能力。通过改善传统的聚焦误差信号曲线，并利用数字伺服控制方法，在提高系统测量精度的同时，克服了传统对于陡坑或阶梯测量容易脱焦的问题。     

激光跟踪仪两级双轴联动闭环控制系统研究

为保证激光跟踪仪的跟踪精度,设计选择了两级双轴联动控制系统,以直流力矩电机作为第1级控制,为粗调机构;音圈电机作为第2级,为精调机构;并将此2个电机安装于垂直和水平2个方向实现三维空间的跟踪,偏差信号经过PI调节后,生成双极性PWM控制执行机构完成闭环控制。通过这种控制方式,达到了激光跟踪仪的精度要求。     

一种小型激光跟踪测量系统的研制

为实现大尺寸范围内的坐标跟踪测量,研制了一种小型激光跟踪测量系统。设计了光机电一体化的机械结构,实现减小系统体积与提高抗干扰能力。设计了系统的光学模块,通过优化基于位置敏感探测器的目标偏差量采集部分的光路,实现目标允许最大偏差量的增大。通过开展位置敏感探测器的标定实验,完成位置敏感探测器的线性区间与偏差比例系数的测量,为跟踪控制算法开发提供了关键参数。进行了跟踪控制模块的设计,并完成跟踪控制算法的开发,实现系统的快速跟踪测量。开发了系统三维可视化测量软件,实现用户对系统与目标的空间位置及运动状态的实时掌控。实验结果表明,系统的跟踪稳定性与位移分辨力分别为20μm和40μm,系统的跟踪速度最高可达480 mm/s,加速度最高可达506 mm/s²,跟踪距离范围不小于70 m,具有三维坐标测量与三维可视化功能,与现有跟踪仪相比具有体积、重量以及测角范围上的优势,具有良好的跟踪性能与应用前景。     

光刻机工件台宏微系统的滑模变结构控制

为提高光刻机工件台的跟踪精度和响应速度,采用了以直线电机和音圈电机为执行器的宏微控制结构.微动台完成高精度小行程运动,宏动台实现大行程运动同时保证音圈电机不出现位移饱和.通过滑模变结构方法设计控制器以提高控制系统的鲁棒性.根据频率整型法设计了时变滑模面,可以起到低通滤波的效果.变增益切换控制律可以有效地减小抖振现象.仿...     

用于激光测振的聚焦扫描系统

针对单点式激光测振仪在测量中的缺陷,本文提出了一种聚焦扫描的测量方式。利用三个步进电机实现对聚焦扫描的控制,其中一个电机控制透镜的移动实现变焦,另外两个电机控制平面镜转向实现光斑位置的移动。设计了聚焦扫描算法,通过实验验证了该方法的实用性。     

基于音圈电机的柔性杆自抗扰LQR抑振控制算法研究

该研究将音圈电机作动的二重动力吸振器(dynamicvibration absorber, DVA)应用于柔性杆端部来实现振动抑制。为克服柔性杆本身容易受扰和DVA抑振带宽不足的问题，采用两个小型音圈电机构成主动式二重DVA,针对该DVA设计主动振动控制方法。首先，基于柔性杆的动力学等效建立了状态空间模型，在分析音圈电机的驱动特性后，采用线性二次型最优控制(linear quadratic regulator, LQR)反馈控制器最小化扰动通道的传递函数增益，结合非线性跟踪微分器同时滤波和提取微分信号；在此基础上，引入时变增益的扩张状态观测器对模型不确定性、高阶模态以及未知扰动进行补偿。对抑振效果进行仿真分析，结果表明基于音圈电机的二重DVA与自抗扰LQR控制器相结合，抑制柔性杆端残余振动，兼有强鲁棒性和抗扰能力。     

新型激光跟踪测量系统的设计

基于多边法原理,设计出一种新型的激光跟踪测量系统。该系统采用四象限光电池作传感器,准确地测量目标镜反射光线的位置,测量灵敏度为 200mV/mm;以双电机驱动的双轴单转镜作跟踪机构,结构简单,运动灵巧,立体转角约±35 °;模拟式 PID 与数字式 PID 相结合的控制方案,控制精度高,跟踪速度快。实验表明,系统跟踪速度优于 0.7m/s,综合测量精度 1.3μm 。     

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.     

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.     

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.     

Brainstorming for ISO Strategy 2016-2020

正Responding to ISO’s appeal for survey for the to-be-developed ISO Strategy Plan for 2016-2020,SAC hosted a special workshop over the needs and comments of various fi elds on June 8 in Beijing.The workshop was attended by ISO President-elect and Ansteel General Manager Zhang Xiaogang,SAC Vice-Administrator Yu Xinli,and 30 experts from     

CNAS Passes APLAC's PTP Review

正The review group of Asia Pacific Laboratory Accreditation Cooperation(APLAC)carried out a 4-day peer review of the proficiency testing provider(PTP)for China National Accreditation Service for Conformity Assessment(CNAS)from July 28 to 31,2014.CNAS passed the PTP review with excellent performance.Two senior peer reviewers of APLAC made a comprehensive,rigorous and detailed review of CNAS’s PTP accreditation activities,and made the on-spot inspection of the review groups in Shanghai and Shenzhen respectively.     

新闻(英文)

正China and Greece Sign the Standardization Cooperation Agreement Witnessed by Chinese Premier Li Keqiang and Greek Prime Minister Antonis Samaras,AQSIQ Minister Zhi Shuping and ELOT Chairman and Executive Director Angelos Tolkas signed the SAC-ELOT Standardization Cooperation Agreement.The Agreement is one of the critical cooperation documents signed during Li Keqiang’s visit in Greece,encouraging China and Greece to