PLC系统信号干扰与防范措施

结合现场,分析PLC控制系统中信号产生干扰的原因,和可能引起模板故障的因素,并提出相应解决方法.     

混凝土行业中基于JCS的海量数据协同模块的研究

随着国内预拌混凝土行业的发展,混凝土企业高层越来越意识到搅拌站信息化管理的必要性,各种混凝土搅拌站ERP软件在国内得到了迅速的发展,通过这种软件的信息化管理,后台数据库每天都会产生大量的生产数据。为了避免搅拌站之间的恶性竞争,混凝土行业协会和政府部门需要对某个区域乃至整个行业的搅拌站的生产运营情况有实时的了解,以便对其进行监管,最终促进行业的公平竞争。本文结合国内混凝土行业自身的特点,阐述了混凝土行业海量数据协同的总体构想和数学模型,之后从多维度论述了基于JCS多级缓存的海量数据协同模块的设计,最后,采用Socket的方式最终实现了Server端与Client端的一对多的数据通信。     

柏木油回顾

本文简要回顾中国柏木油之产量、质量和价格。笔者以为中国柏木油价格在国际市场走低多年 ,其主因是香气质量。为改进柏木油香气质量 ,主张以水蒸汽蒸馏技术取代水上蒸馏法 ,不赞成用干馏法或“红锅”法来制取柏木原油。对现有柏木宝贵的天然资源 ,主张由林业部门主导统筹规划和进行科学开发及综合利用。     

封头盘管槽的制造

我司为台资厂制造EPS槽为例。对封头盘管式罐的生产工艺论述。说明了筒体盘管和封头盘管的制造和安装工艺。     

国内陶瓷市场出现六大变化

1产业结构调整取得重大进展 加入WTO以来，我国陶瓷工业以结构调整为主线，使组织结构、产品结构、资本结构、行业结构等都发生了深刻变化。组织结构变大通过以产权为纽带，以名牌产品为龙头，网罗、兼并、吸收资本，组建企业集团，调整组织结构，使企业得到不断壮大，朝着大而强方向发展，像新中源就是很好的典型。此外，通过“三改一加强”，许多企业内部组织机构实现了与市场对接，企业内部人力资源结构也得到了不断优化。     

Controllable synthesis of poly(N-vinylpyrrolidone) and its block copolymers by atom transfer radical polymerization

At room temperature atom transfer radical polymerization (ATRP) of N-vinylpyrrolidone (NVP) was carried out using 5,5,7,12,12,14-hexamethyl-1,4,8,11-tetra-azacyclo-tetradecane (Me₆Cyclam) as ligand in 1,4-dioxane/isopropanol mixture. Methyl 2-chloropropionate (MCP) and copper(I) chloride were used as initiator and catalyst, respectively. The polymerization of NVP via ATRP could be mediated by the addition of CuCl₂. The resultant poly(N-vinylpyrrolidone) (PNVP) has high conversion of up to 65% in 3 h, a controlled molecular weight close to the theoretical values and narrow molecular weight distribution between 1.2 and 1.3. The living nature of the ATRP for NVP was confirmed by the experiments of PNVP chain extension. With PNVP-Cl as macroinitiator and N-methacryloyl-N′-(α-naphthyl)thiourea (MANTU) as a hydrophobic monomer, novel fluorescent amphiphilic copolymers poly(N-vinylpyrrolidone)-b-poly(N-methacryloyl-N′-(α-naphthyl)thiourea) (PNVP-b-PMANTU) were synthesized by ATRP. PNVP-b-PMANTU copolymers were characterized by ¹H NMR, GPC-MALLS and fluorescence measurements. The results revealed that PNVP-b-PMANTU presented a blocky architecture.     

Kinetics modelling of Fischer-Tropsch synthesis over an industrial Fe-Cu-K catalyst

The kinetic experiments of Fischer-Tropsch synthesis (FTS) over an industrial Fe-Cu-K catalyst are carried out in a micro-fixed-bed reactor under the conditions as follows: temperature of 493-542 K, pressure of 10.9-30.9 bar, H₂/CO feed ratio of 0.98-2.99, and space velocity of 4000-10?000 h⁻¹. The effects of secondary reactions of olefins are investigated by co-feeding C₂H₄ and C₃H₆. A detailed kinetics model taking into account the increasingly proven evidence of the olefin re-adsorption mechanism is then proposed. In this model, different sites are assumed for FTS reactions and water gas shift (WGS) reaction, respectively. Rate expressions for FTS reactions are based on the carbide polymerisation mechanism, in which olefin re-adsorption is considered to be a reverse step of olefin desorption reaction. Rate expression for WGS reaction is based on the formate mechanism. An integral reactor model considering both FTS and WGS kinetics is used to describe the reaction system, and the simultaneous estimation of kinetic parameters is conducted with non-linear regression procedure. The optimal model shows that the rate determining steps in FTS reactions proceed via the desorption of hydrocarbon products and the adsorption of CO and the slowest step in WGS reaction is the desorption of gaseous carbon dioxide via formate intermediate species. The activation energies of FTS reactions and WGS reaction are in good agreement with literature values.     

关于木素生物降解酶类活力测定问题的讨论

由于木素结构和生物降解过程复杂多样，全面测定一个菌株的木素降解活力也比较困难，目前已发现三类主要参与木素降解的酶类（LIP、MnP、漆酶），但至今很少有国际上公认的酶活力测定方法，也未见到能把某一菌株木素降解酶类的活力与其在木质纤维材料中降解木素的能力定量关联的报导。本文综合评述了几类主要的木素降解酶类活力测定方法的作用机制和存在的问题，指出一个菌株的木素降解活力是由它的生理特性和总体代谢能力共同决定的，仅由一类或几类酶活力的表现水平难以对其作出确切的评价，从这个角度出发进行研究才能更客现他认识菌株的木素降解活力．     

A Novel Inorganic Polymer as Cathode Material for Secondary Lithium Batteries

Summary: This paper introduces a new inorganic poly(phosphazene disulfide) material. With unique element composition and molecular structure, the polymer has noncombustible safety and preferable conductivity. When used as cathode material for rechargeable lithium batteries, the polymer's first discharge capacity is as high as 467.9 mAh · g^?1, which can be retained at 409.9 mAh · g^?1 after 60 repeated cycles. Therefore, it has a great application potential in the field of lithium batteries.

Replacement of the Cl atoms by S? S groups by refluxing Na₂S₂ and linear poly(dichloro‐phosphazene).     

Kinetics of Thermal Dehydroxylation and Carbonation of Magnesium Hydroxide

The kinetics of simultaneous dehydroxylation and carbonation of precipitated Mg(OH)₂ were studied using isothermal and nonisothermal thermogravimetric analyses. Specimens were analyzed using X-ray diffraction, transmission electron microscopy, and through measurements of the volume of carbon dioxide evolved in a subsequent reaction with hydrochloric acid. From 275° to 475°C, the kinetics of isothermal dehydroxylation in helium were best fit to a contracting-sphere model, yielding an activation energy of 146 kJ/mol, which was greater than values reported in the literature for isothermal dehydroxylation under vacuum (53–126 kJ/mol). The carbonation kinetics were complicated by the fact that dehydroxylation occurred simultaneously. The overall kinetics also could be fit to a contracting-sphere model, yielding a net activation energy of 304 kJ/mol. The most rapid carbonation kinetics occurred near 375°C. At this temperature, Mg(OH)₂ underwent rapid dehydroxylation and subsequent phase transformation, whereas thermodynamics favored the formation of carbonate. During carbonation, MgCO₃ precipitated on the surface of disrupted Mg(OH)₂ crystals acting as a kinetic barrier to both the outward diffusion of H₂O and the inward diffusion of CO₂.