基于同步Petri网的立体车库控制系统研究

随着工业工程的不断发展,利用PLC设计的工业控制系统也日趋复杂,导致传统方法设计PLC控制系统时逻辑更复杂、更易出错、检错也更加不易。因此,在设计PLC控制系统时,对系统进行合理的建模与分析具有十分重要的意义,在设计阶段即尽可能地完整复现控制过程、降低出错率、降低开发周期。利用同步Petri网,以升降横移式立体车库的PLC控制系统为对象,对其进行建模、分析,保证系统功能的完整性及有效性,进而编写程序。     

基于Petri网的耳机部件自动装配设备PLC控制系统研究

为解决在具有并发、竞争控制的PLC控制系统中传统的PLC程序设计方法存在不适用,而且易导致程序出错并且难以检查错误等问题,利用Petri网具有图形描述、模拟特点以及分析具有并发和冲突环节等复杂事件的能力,结合Petri网的建模方法与ExSpect模型仿真技术对耳机部件自动装配设备控制系统进行建模与仿真分析,然后利用仿真结果再结合工艺流程,直观地指导构建PLC 控制系统的程序。仿真与调试结果表明：该方法可避免设备运行时相关部件的冲撞等实际问题,缩短调试时间,保证了PLC控制系统可行、可靠性。     

控制系统中PLC对故障诊断的作用

在PLC控制系统中,其主要包括的部件有PLC以及与PLC相连的输入输出设备。当PLC控制系统在运行过程中时,由于PLC本身或者是外部的输入输出设备的故障会直接影响整个系统的运行状况。为了整个控制系统的控制质量更能够符合人们的需求,所以需要进行PLC控制系统故障的分析。     

PLC控制系统入侵检测技术研究

由于PLC控制系统有别于传统的计算机网络系统,传统的病毒检测、网络入侵检测技术无法有效检测PLC控制系统攻击。设计一种非介入式的PLC控制系统入侵检测方法,采用以太网数据监听与现场控制网数据监听技术相结合的方法,通过PLC控制系统输入输出业务信息一致性检测,实现PLC恶意代码篡改数据攻击检测,通过业务规则检测实现违反业务约束的恶意控制指令检测。完成了PLC控制系统入侵检测系统开发,测试表明系统可以有效检测PLC系统的恶意代码攻击和恶意控制指令攻击。     

控制系统中PLC对故障诊断的作用

PLC控制系统目前广泛应用于我们的生产和生活中,但是控制系统在运行时常会出现这样和那样的问题,本文主要描述了PLC控制系统出现故障时,如何应用PLC排除故障,并分析了故障的原因,可以给广大从事PLC控制系统设计和维护人员以借鉴。     

超细粉磨系统的PLC控制

随着自动化控制设备、工业控制网络及计算机技术的发展，越来越多的工厂已经从原来的继电器控制不断向PLC控制转变。本文主要研究了PLC控制系统在超细粉磨系统中的应用，阐述了PLC的选型及其硬件配置、电路元件的选择、系统软件的设计等。     

PLC控制系统在超滤水处理过程中的应用

PLC控制系统全称是“可编程逻辑控制器”,是一种基于数字运算基础上的操作控制系统。文中通过探讨PLC控制系统在超滤水处理过程中的应用,提出了超滤水处理过程中PLC控制过程设计、模块设计的具体对策,这对促进PLC控制系统在水处理工程中的应用、提升超滤水处理过程中的控制质量具有一定的现实意义。     

佳灵公司成为中国石化物资装备部第一家国产高压变频器合格供应商

佳灵公司为中国石化天津热电部7#炉甲、乙两台6kV高压吸风机设计生产的高压变频调速装置成功投入运行。该系统是国内首次将PLC控制系统直接嵌入高压变频调速控制柜中,实现了开关逻辑联锁保护、变频器远程操作、变频器检修时风门挡板开度自动跟踪及自动工频切换一体化控制。     

基于计算机组态的液位控制系统的设计与实现

本文针对利用可编程序控制器和组态王开发的“计算机组态液位控制系统”的设计与实现进行了剖析。对系统设计实现过程中的控制工艺及要求、PLC控制系统输入输出分配、PLC控制系统程序、组态王监控画面的设计、数据库词典的定义、监控系统动画设置等内容进行了重点分析。通过实际的调试运行,实现了系统的功能。     

PLC控制系统在油田生产中的应用研究

随着我国经济对原油的需求日渐增长,油田污染问题受到国人的广泛关注。针对该问题,本文采用PLC控制系统完成测控任务,软件系统中由SIEMENS S7—300 PLC完成测控任务,其中PLC的工作方式采用循环扫描,通过PID控制达到控制信号的目的。具体应用案例分析表明,该PLC控制系统在污水处理站上可以节约投入成本,能够较好地处理污水污染。     

Resolution Enhancement Technology:Integrated Process Solutions using OPC

DUV lithography, using the 248 nm wavelength, is a viable manufacturing option for devices with features at 130 nm and less. Given the low kl value of the lithography, integrated process development is a necessary method for achieving acceptable process latitude. The application of assist features for rule based OPC requires the simultaneous optimization of the mask, illumination optics and the resist.Described in this paper are the details involved in optimizing each of these aspects for line and space imaging.A reference pitch is first chosen to determine how the optics will be set. The ideal sigma setting is determined by a simple geometrically derived expression. The inner and outer machine settings are determined, in turn,with the simulation of a figure of merit. The maximum value of the response surface of this FOM occurs at the optimal sigma settings. Experimental confirmation of this is shown in the paper.Assist features are used to modify the aerial image of the more isolated images on the mask. The effect that the diffraction of the scattering bars (SBs) has on the image intensity distribution is explained. Rules for determining the size and placement of SBs are also given.Resist is optimized for use with off-axis illumination and assist features. A general explanation of the material' s effect is discussed along with the affect on the through-pitch bias. The paper culminates with the showing of the lithographic results from the fully optimized system.     

Cost-effective test solutions for smart card and other integrated flash applications

From its emergence in the late 1980s as a lower cost alternative to early EEPROM technologies, flash memory has evolved to higher densities and speedsand rapidly growing acceptance in mobile applications.In the process, flash memory devices have placed increased test requirements on manufacturers. Today, as flash device test grows in importance in China, manufacturers face growing pressure for reduced cost-oftest, increased throughput and greater return on investment for test equipment. At the same time, the move to integrated flash packages for contactless smart card applications adds a significant further challenge to manufacturers seeking rapid, low-cost test.     

An improved parallel thinning algorithm with two subiterations

The parallel thinning algorithm with two subiterations is improved in this paper. By analyzing the notions of connected components and passes, a conclusion is drawn that the number of passes and the number of eight-connected components are equal. Then the expression of the number of eight-connected components is obtained which replaces the old one in the algorithm. And a reserving condition is proposed by experiments, which alleviates the excess deletion where a diagonal line and a beeline intersect. The experimental results demonstrate that the thinned curve is almost located in the middle of the original curve connectivelv with single pixel width and the processing speed is high.     

Theoretical analysis of the relationship between the Brillouin gain coefficient and the strain in the optical-fiber sensors

The relation between the power of the Brillouin signal and the strain is one of the bases of the distributed fiber sensors of temperature and strain. The coefficient of the Bfillouin gain can be changed by the temperature and the strain that will affect the power of the Brillouin scattering. The relation between the change of the Brillouin gain coefficient and the strain is thought to be linear by many researchers. However, it is not always linear based on the theoretical analysis and numerical simulation. Therefore, errors will be caused if the relation between the change of the Brillouin gain coefficient and the strain is regarded as to be linear approximately for measuring the temperature and the strain. For this reason, the influence of the parameters on the Brillouin gain coefficient is proposed through theoretical analysis and numerical simulation.     

Novel fiber-optical interferometer with miniaturized probe for in-hole measurements

Today, micro-system technology and the development of new MEMS （Micro-Electro-Mechanical Systems） are emerging rapidly. In order for this development to become a success in the long run, measurement systems have to ensure product quality. Most often, MEMS have to be tested by means of functionality or destructive tests. One reason for this is that there are no suitable systems or sensing probes available which can be used for the measurement of quasi inaccessible features like small holes or cavities. We present a measurement system that could be used for these kinds of measurements. The system combines a fiber optical, miniaturized sensing probe with low-coherence interferometry, so that absolute distance measurements with nanometer accuracy are possible.     

Study of waveguide coupling efficiency in hybrid silicon lasers

This paper presents a new method to increase the waveguide coupling efficiency in hybrid silicon lasers. We find that the propagation constant of the InGaAsP emitting layer can be equal to that of the Si resonant layer through improving the design size of the InP waveguide. The coupling power achieves 42% of the total power in the hybrid lasers when the thickness of the bonding layer is 100 nm. Our result is very close to 50% of the total power reported by Intel when the thickness of the thin bonding layer is less than 5 nm. Therefore, our invariable coupling power technique is simpler than Intel＇s.     

Curved crystal spectrometer for the measurement of X-ray lines from laser-produced plasmas

In order to diagnose the laser-produced plasmas, a focusing curved crystal spectrometer has been developed for measuring the X-ray lines radiated from a laser-produced plasmas. The design is based on the fact that the ray emitted from a source located at one focus of an ellipse will converge on the other focus by the reflection of the elliptical surface. The focal length and the eccentricity of the ellipse are 1350 mm and 0.9586, respectively. The spectrometer can be used to measure the X- ray lines in the wavelength range of 0.2-0.37 nm, and a LiF crystal （200） （2d = 0.4027 nm） is used as dispersive element covering Bragg angle from 30° to 67.5°. The spectrometer was tested on Shengnang- Ⅱ which can deliver laser energy of 60-80 J/pulse and the laser wavelength is 0.35 μm. Photographs of spectra including the 1 s2p ^1P1-1s^2 ^1S0 resonance line（w）, the 1s2p ^3P2-1s^2 1S0 magnetic quadrupole line（x）, the 1s2p ^3P1-1 s^2 ^1S0 intercombination lines（y）, the 1 s2p ^3S~1-1 s^2 ^1S0 forbidden line（z） in helium-like Ti Ⅹ Ⅺ and the 1 s2s2p ^2P3/2-1 s622s ^2S1/2 line（q） in lithium-like Ti Ⅹ Ⅹhave been recorded with a X-ray CCD camera. The experimental result shows that the wavelength resolution（λ/△ 2） is above 1000 and the elliptical crystal spectrometer is suitable for X-ray spectroscopy.     

Preparation and Characterization of TaN ALD Precursors

High purity organic-tantalum precursors for thin film ALD TaN were synthesized and characterized.Vapor pressure and thermal stability of these precursors were studied.From the vapor pressure analysis,it was found that TBTEMT has a higher vapor pressure than any other published liquid TaN precursor,including TBTDET,TAITMATA,and IPTDET.Thermal stability of the alkyl groups on the precursors was investigated using a 1H NMR technique.The results indicated that the tertbutylimino group is the most stable group on TBTDET and TBTEMT as compared to the dialkylamido groups.Thermal stability of TaN precursors decreased in the following order:TBTDET ＞ PDMAT ＞ TBTEMT.In conclusion,precursor vapor pressure and thermal stability were tuned by making slight variations in the ligand sphere around the metal center.     

A rigorous proof of MIMO channel capacity’s increase with antenna number

It is well known that adding more antennas at the transmitter or at the receiver may offer larger channel capacity in the multiple-input multiple-output（MIMO） communication systems. In this letter, a simple proof is presented for the fact that the channel capacity increases with an increase in the number of receiving antennas. The proof is based on the famous capacity formula of Foschini and Gans with matrix theory.     

Electronic Structure of Semiconductor Nanocrystals

This paper reviews our recent development of the use of the large-scale pseudopotential method to calculate the electronic structure of semiconductor nanocrystals, such as quantum dots and wires, which often contain tens of thousands of atoms. The calculated size-dependent exciton energies and absorption spectra of quantum dots and wires are in good agreement with experiments. We show that the electronic structure of a nanocrystal can be tuned not only by its size,but also by its shape. Finally,we show that defect properties in quantum dots can be significantly different from those in bulk semiconductors.