Synthesis of amphiphilic magnetic microspheres by dispersion copolymerization of styrene and poly(ethylene oxide) macromonomer

Amphiphilic magnetic microspheres ranging in diameter from 5 to 100 µm were prepared by dispersion copolymerization of styrene and poly(ethylene oxide) vinylbenzyl (PEO‐VB) macromonomer (MPEO) in the presence of Fe₃O₄ magnetic fluid. The effects of various polymerization parameters on the average particle size were systematically investigated. The average particle size was found to increase with increasing styrene concentration and initiator concentration. It also increased with decreasing stabilizer concentration and molecular weight of MPEO. The content of the hydroxyl groups localized in the microspheres ranged from 0.01 to 0.2 mmol g^?1. © 2003 Society of Chemical Industry     

Operational aspects of adsorption air‐conditioner used in diesel locomotive

A locomotive cabin adsorption air‐conditioner has been equipped in #DF4B‐2369 locomotive; and has been successfully run for 2 years. It is powered by waste heat from the exhaust of the diesel engine. The influence on heat transfer is described by the equivalent heat transfer coefficient or thermal resistance of components inside the adsorber. The variation of adsorption capacity is expressed by a non‐equilibrium adsorption function. The dynamic heat transfer process of adsorption air‐conditioning system is treated with the lumped parameter method. Some typical running experimental results are present. The diesel engine rotating speed and locomotive speed influenced on the refrigeration system are discussed. The maximum mean refrigeration power is regarded as an objective function. Based on experiments and theoretical analysis, the running characteristics of the air‐conditioning system are optimized. Some techniques of performance improvement are suggested as well. Copyright © 2006 John Wiley & Sons, Ltd.     

A new Pd-oxide-Al/sub 0.3/Ga/sub 0.7/As MOS hydrogen sensor

A new and interesting Pd-oxide-Al/sub 0.3/Ga/sub 0.7/As MOS hydrogen sensor has been fabricated and studied. The steady-state and transient responses with different hydrogen concentrations has been measured at various temperatures. Based on the large Schottky barrier height and presence of oxide layer, the studied device exhibits a high hydrogen detection sensitivity and wide temperature operating regime. The studied device exhibits the low-leakage current and obvious current changes when exposed to hydrogen-contained gas. Even at room temperature, a very high hydrogen detection sensitivity of 155.9 is obtained when a 9090 ppm H/sub 2//air gas is introduced. Furthermore, when exposed to hydrogen-contained gas at 95/spl deg/C, both the forward and reverse currents are substantially increased with increased hydrogen concentration. In other words, the studied device can be used as a hydrogen sensor under the applied bidirectional bias. Under the applied voltage of 0.35 V and 9090 ppm H/sub 2//air hydrogen ambient, a fast adsorption response time about 10 s is found. The transient and steady-state characteristics of hydrogen adsorption are also investigated.     

合成己二腈反应技术研究——(Ⅴ)己二腈工业反应过程模拟与反应器改造

对己二腈工业反应器提出了两釜串联带回流的模型,通过模拟计算得出模型的级间返混系数 f=6的结论。该模型能较好地预测工业反应器中物料组分浓度变化和气、液两相的流动特性;指出了现工业反应器的鼓泡中和段体积偏小是造成己二酸浓度偏高的关键;提出了可以通过增加串连一个鼓泡预反应段的改造方案,能有效地降低己二酸的浓度,从7%降至4%左右,从而能较好地减缓腐蚀和结焦。     

氧化铝陶瓷缺口件循环疲劳及断裂机理

用实验方法研究了Ａｌ＿２Ｏ＿３陶瓷缺口试件在循环载荷作用下的疲劳寿命。结果表明，缺口导致的应力集中效应显著降低了循环疲劳寿命；若用缺口根部最大应力为应力水平，则不同缺口半径陶瓷试件具有相同疲劳断裂规律，说明陶瓷材料的疲劳集中系数和理论应力集中系数相同。本文还分析讨论了陶瓷材料的循环疲劳寿命表达式和循环疲劳断裂机理。     

An algebraic theory of object-oriented systems

The paper presents an algebraic specification of net objects. By net objects we mean those that are defined in object-oriented paradigms and those defined with nested relations in complex database models. An algebraic specification is set up that involves structures of net objects, accesses of net objects, and some features of object-oriented programming, such as multiple inheritance and polymorphism. Objects and their relationships are then characterized formally in the modeling, which utilizes the hierarchical approach in the algebraic theory of abstract data types, and is further developed by adding mechanisms from existing object systems. Categories of net objects are presented with the properties of accesses among them     

以网格曲线为连续条件的光滑曲面

本文提出一种以网格边界曲线定义曲面的方法。曲面的计算式唯一地由网格的四条边界线的参数而定，各网格间连接的光滑度完全由网格间的边界线的光滑度来决定。当网格间的边界线具有Ｃ~１连续以上的光滑度时，网络曲面间将自动保证是Ｃ~１连续的，否则将是Ｃ~０连续。利用这个方法，可以方便地从线框模型（ｗｉｒｅ－ｆｒａｍｅｍｏｄｅｌ）建立面模型（ｓｕｒｆａｃｅｍｏｄｅｌ）。     

COATES GRAPH APPROACH FOR GENERATING SYMBOLIC NETWORK FUNCTION

In this paper, symbolic code matrix ,constant matrix and count matrix are defined .The first twomatrices are used to describe the elemental expression of augmented matrix and the nede admittance equa-tion is thus obtained. The third matrix is used to obtain the incoming degree matrix, and according to thematrix all the 1- factors of the Coates graph are given. By using the data code, the determinant is expandedand the same items in the expansion are merged. Thus the symbolic network function in which no term can-cellation occurs is generated.     

The Solutions for Adjustment and Reconstruction of Water-Drive Surface Systems in the Old Areas of Daqing Oilfield

Introduction 　　Owing to long-time running, more facilities including stations, pipelines, vessels have become corrosive and aged ,some process has grown old, it has exert more burden for the maintenance and repair.Simultaneously, the fluid production rate, oil production rate and water injection rate has changed greatly so that the inflicts and problems from the established surface systems will become more obvious. Energy cost of production and running has increasing continuously. Capacity has been unbalance in systems and areas. 　　……