DCS在化工生产中的应用

随着社会对化工产品的需求不断增长,化工企业也在不断扩大生产规模,生产设备越来越复杂,对生产控制系统提出的要求也越高。分布式控制系统(distributed control system,DCS)有着网络化与体系化的结构,能够实现化工生产设备的自动化与智能化控制,满足现阶段化工生产的要求。对DCS的结构与功能进行简单的阐述,明晰DCS在化工生产中的应用优势,分析DCS在化工生产中的具体应用,旨在加深对DCS的了解,使DCS在化工生产中得到更为广泛的应用。     

探究DCS控制系统在医药化工中的应用

DCS控制系统是一种使用微处理器作为基础,依照控制功能分散、显示操作集中、兼顾分而自治以及综合协调的设计原则研发出来的新型仪表控制系统。DCS分散控制系统最常应用与化工行业领域,即使在不同的化工类型行业中也都有着广泛的应用,同时具有广泛的发展前景。以医药化工行业来说,DCS分散控制系统在医药化工行业中的应用已经非常普遍和深入,对提升医药化工行业的质量控制以及生产安全有很大的帮助。本文将通过对DCS控制系统的内容进行阐述,进而对DCS控制系统在医药化工中的应用做出具体的分析和讨论。     

化工生产中DCS自动控制的应用研究

随着社会主义经济的不断进步,我国的科技生产水平也有了显著的提高,各个领域对于自动化的应用越来越广泛,越来越多的积极手段应用到化工生产中来,DCS自动化控制在化工生产中就得到了很大的应用,成为了最重要的一项技术之一,使得化工行业得到了飞速的发展,本文针对DCS自动控制技术在化工生产中的应用进行深入探讨.     

WebField ECS-700 DCS在聚甲醛生产中的应用

简要介绍了WebField ECS-700 DCS系统,聚甲醛的性质及生产方法,重点介绍了控制系统的总体设计方案和系统配置,以及在兖矿鲁南化工有限公司4万吨/年聚甲醛装置中的应用情况。     

DCS系统可靠性与抗干扰性的提升策略

DCS系统(集散控制系统)是目前化工、电力、冶金等行业过程控制的主流系统,应用十分广泛。我公司自备热电厂采用艾默生公司的Ovation DCS系统,系统的可靠性和抗干扰能力直接影响机组的稳定运行。本文对DCS系统的可靠性和抗干扰性进行了全面的分析,总结出一些提高DCS系统可靠性和抗干扰性的策略。     

PLC控制系统与DCS控制系统的优势分析

PLC和DCS第三代控制系统突出代表,在诸多工业控制领域如冶金、电力、石油、化工、轻工等发展迅猛。PLC和DCS两大控制系统具有各自的特点,二者功能方面虽各有千秋,但在实际生产生活中却能结合使用,而且效果更好。     

DCS下锅炉系统自动控制系统的应用探析

DCS下的锅炉系统自动控制系统是工业自动化控制系统的重要一部分,随着科学技术的发展,DCS系统在工业自动化控制领域的应用已经越来越成熟了,而且应用的范围也越来越广。DCS系统实质上是针对于PC局域网,并且借助PC局域网,把局域网实时性的突出性和可靠性加以小红分的运用。下面就对锅炉系统自动化控制系统在某品牌DCS系统下的应用进行分析。     

对电厂DCS自动控制系统的运用浅析

电厂在我国的经济发展当中起到了重要的作用,随着发电行业的不断发展,其自动化水平逐渐提高,为了提高电厂的生产效率和生产安全性,需要发电厂建立适合自己的自动控制系统,目前在大型火电厂当中,DCS自动控制技术得到了广泛地应用,通过计算机技术与发电设备结合,以此来提高电厂的自动化水平,本文结合DCS技术的系统构成,对电厂DCS自动控制系统的运用进行分析。     

DCS系统在电厂中的应用分析

随着仪表自动化技术的不断发展,DCS系统在很多领域得到了较广泛的应用。对于电厂企业来说,DCS系统的应用为电厂热力系统的保护控制与参数调节起着很重要的作用。本文就仪表发展及DCS系统在电厂中的应用问题对仪表的发展历史进行了简单介绍,并结合实际控制系统着重分析了DCS系统目前在电厂自动控制领域中的应用。     

浅谈火电厂测控系统干扰及处理办法

随着计算机控制技术的飞速发展,DCS应用于发电厂控制系统中。热工测控系统的可靠性直接影响到发电厂的安全生产和经济运行。其中,系统的抗干扰能力是关系到整个系统可靠运行的关键。为保证热工控制系统的正常运行,防止和消除干扰是一个不容忽视的环节。下面就热工控制系统在应用中的干扰与抗干扰问题作相关介绍。     

Development of the readout system for waveguide multilayer optical card

Waveguide multilayer optical card （WMOC） is a novel storage device of three-dimensional optical information. An advanced readout system fitting for the WMOC is introduced in this paper. The hardware mainly consists of the light source for reading, WMOC, motorized stages addressing unit, microscope imaging unit, CCD detecting unit and PC controlling ＆ processing unit. The movement of the precision motorized stage is controlled by the computer through Visual Basic （VB） language in software. A control panel is also designed to get the layer address and the page address through which the position of the motorized stages can be changed. The WMOC readout system is easy to manage and the readout result is directly displayed on computer monitor.     

Nanoimprint Lithography -A Next Generation High Volume Lithography Technique

IntroductionNanoimprint Lithography is a well-acknowl-edged low cost, high resolution, large area pattern-ing process. It includes the most promising methods,high-pressure hot embossing lithography (HEL) [2],UV-cured imprinting (UV-NIL) [3] and micro contactprinting (m-CP, MCP) [4]. Curing of the imprintedstructures is either done by subsequent UV-lightexposure in the case of UV-NIL or by cooling downbelow the glass transition temperature of the ther-moplastic material in case of HEL…     

Collinear phase-matching study of terahertz-wave generation via difference frequency mixed in GaAs and Inp

The collinearly phase-matching condition of terahertz-wave generation via difference frequency mixed in GaAs and InP is theoretically studied. In collinear phase-matching, the optimum phase-matching wave hands of these two crystals are calculated. The optimum phase-matching wave bands in GaAs and lnP are 0.95-1.38μm and 0.7-0.96μm respectively. The influence of the wavelength choice of the pump wave on the coherent length in THz-wave tuning is also discussed. The influence of the temperature alteration on the phase-matching and the temperature tuning properties in GaAs crystal are calculated and analyzed. It can serve for the following experiments as a theoretical evidence and a reference as well.     

Effects of the alloy compositions on the phonon-polaritons in ternary mixed crystals

Composition dependence of bulk and surface phonon-polaritons in ternary mixed crystals are studied in the framework of the modified random-element-isodisplacement model and the Bom-Huang approximation. The numerical results for Several Ⅱ - Ⅵ and Ⅲ- Ⅴ compound systems are performed, and the polariton frequencies as functions of the compositions for ternary mixed crystals AlxGa1-xAs, GaPxAS1-x, ZnSxSe1-x, GaAsxSb1-x, GaxIn1-xP, and ZnxCd1-xS as examples are given and discussed. The results show that the dependence of the energies of two branches of bulk phonon-polaritons which have phonon-like characteristics, and surface phonon-polaritons on the compositions of ternary mixed crystals are nonlinear and different from those of the corresponding binary systems.     

Influence of PVK ： NPB hole transporting layer on the characteristics of organic light-emitting devices

A doping system consisting of NPB and PVK is employed as a composite hole transporting layer （CHTL）. By adjusting the component ratio of the doping system, a series of devices with different concentration proportion of PVK ： NPB are constracted. The result shows that doping concentration of NPB enhances the competence of hole transporting ability, and modifies the recombination region of charge as well as affects the surface morphology of doped film. Optimum device with a maximum brightness of 7852 cd/m^2 and a power efficiency of 1.75 lm/W has been obtained by choosing a concentration proportion of PVK ： NPB at 1：3.     

New insert layer structure OLEDs

An insert layer structure organic electroluminescent device（OLED） based on a new luminescent material （Zn（salen）） is fabricated. The configuration of the device is ITO/CuPc/NPD/Zn（salen）/Liq/LiF/A1/CuPc/NPD/Zn（salen）/Liq/LiF/A1. Effective insert electrode layers comprising LiF（1nm）/Al（5 nm） are used as a single semitransparent mirror, and bilayer cathode LiF（1 nm）/A1（100 nm） is used as a reflecting mirror. The two mirrors form a Fabry-Perot microcavity and two emissive units. The maximum brightness and luminous efficiency reach 674 cd/m^2 and 2.652 cd/A, respectively, which are 2.1 and 3.7 times higher than the conventional device, respectively. The superior brightness and luminous efficiency over conventional single-unit devices are attributed to microcavity effect.     

Analysis of error performance on Turbo coded FDPIM

Due to variable symbol length of digital pulse interval modulation（DPIM）, it is difficult to analyze the error performances of Turbo coded DPIM. To solve this problem, a fixed-length digital pulse interval modulation（FDPIM） method is provided. The FDPIM modulation structure is introduced. The packet error rates of uncoded FDPIM are analyzed and compared with that of DPIM. Bit error rates of Turbo coded FDPIM are simulated based on three kinds of analytical models under weak turbulence channel. The results show that packet error rate of uncoded FDPIM is inferior to that of uncoded DPIM. However, FDPIM is easy to be implemented and easy to be combined, with Turbo code for soft-decision because of its fixed length. Besides, the introduction of Turbo code in this modulation can decrease the average power about 10 dBm, which means that it can improve the error performance of the system effectively.     

A method for calculating the center position of collimated light

It is a key problem to accurately calculate beam spots＇ center of measuring the warp by using a collimated laser. A new method, named double geometrical center method （DGCM）, is put forward for the first time. In this method, a plane wave perpendicularly irradiates an aperture stop, and a charge couple device （CCD） is employed to receive the diffraction-beam spots, then the geometrical centers of the fast and the second diffraction-beam spots are calculated respectively, and their mean value is regarded as the center of datum beam. In face of such adverse instances as laser intension distributing defectively, part of the image being saturated, this method can still work well. What＇s more, this method can detect whether an unacceptable error exits in the courses of image receiving, processing and calculating. The experimental results indicate the precision of this method is high.     

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.     

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.