红外研究丁羟二异氰酸酯的固化反应动力学

用红外分光光度计研究了端羟基聚丁二烯(HTPBD)与二异氰酸酯的反应动力学,结果表明,NCO与OH的反应为二级动力学反应,由于位阻效应和共轭效应,MDI比TDI的反应活性大得多,前者的反应速率常数大约是后者的10～20倍。反应速率常数及活化能随NCO的过量而有所变化。在NCO过量体系中。TDI-HTPBD体系中有次级反应发生,由于氢键的作用,次级反应为对于氨基甲酸酯基为二级、NCO为一级的三级反应动力学.由于位阻效应,MDI体系很难发生次级反应。     

混凝土受拉断裂的破坏机理

本文从试验现象出发,建立了以数理统计为基础的混凝土受拉全过程曲线方程。研究表明,混凝土受拉应力应变全曲线是混凝土试件内部的粘结界面与水泥胶合物在外拉力作用下逐步断裂造成的。文章所建立的方法不仅可以解释许多试验现象,模拟混凝土受拉全曲线,而且还可以得出试验中难以测出的结果。     

带有外界约束的人口扩散系统的最优出生率控制

本文考虑单边约束的依赖于年龄的人口扩散系统，讨论其最优出生率（边界）控制，得到其最优控制的存在性的必要条件。     

外循环型鼓泡式反应器气含率及循环液速率

对直径２８０ｍｍ、扩大直径５００ｍｍ、外循环管直径６５ｍｍ、总高２９００ｍｍ的外循环型鼓泡式反应器，在气体空塔线速Ｕｇ为０．０４－０．５５ｍ／ｓ时，用静压差法和脉冲示踪法测定了不同部位的气含率Ｅｇ，Ｅｐｇ和循环液速率ｕ１，并获得了它们的关联式：对反应段，Ｅｇ＝０．４５５６Ｕ＾０．３１９８ｇ〔Ｕｇ／（Ｕｇ＋Ｕ１）〕＾０．７３９６；对反应器扩大段，Ｅｕｇ＝０．９３８９Ｕ＾０．４４３１ｕｇ；对循环管，Ｅ     

Optimal control of accelerator concentration for resin transfer molding process

Resin cure following mold filling is an essential element in resin transfer molding. To fabricate a composite part with high dimensional stability and minimize residual stress, uniform resin cure should be achieved. This study considers a three-part resin system composed of epoxy, hardener and accelerator. The cure kinetics can be controlled by the accelerator concentration at the injection gate. A numerical method that can predict degree of cure distribution based on accelerator concentration at the gate was proposed. The degree of cure distribution is obtained by solving the resin flow, heat transfer, accelerator concentration and cure problems sequentially. Utilizing this numerical method, an optimal variation of accelerator concentration during mold filling was sought by solving a constrained optimization problem. The effect of accelerator control on degree of cure distribution was investigated and its validity was examined for two different geometries.     

曙光油田超稠油井套管损坏的机理和防治

超稠油特殊的油藏特点决定了其生产周期短、注汽频繁、出砂、汽窜、超覆现象严重，以及套管质量等因素的影响，套管损坏较为严重。对曙光油田超稠油井套管损坏的规律和机理进行了研究，并从钻井和完井工艺的完善、套管钢级和射孔工艺的选择、采油生产参数的确定、注汽管柱隔热效果的提高、防治砂工艺等方面，对套管损坏提出了预防措施和对策。并对套管损坏井制定了修复再利用方案。     

Locked discrete event systems: How to model and how to unlock

To model qualitative aspects of discrete event systems, i.e., the order of the events is of sole importance, we use a triple consisting of the set of all possible events (the alphabet), the set of all behavior (possible strings of events), and the set of all tasks (completed behavior). We use this view to model synchronous as well as asynchronous connection of systems. Moreover, it is easy to define notions like deadlock and livelock in this view. We give a method to construct a second system that, in connection with the original system, gets rid of its deadlock and/or livelock. A state-space representation is introduced. In this representation computations can be done effectively.     

荫罩黑化及DX气与煤气成分的探讨

本文介绍了彩色显像管荫罩黑化反应的机理,详细说明了DX气制气流程,以及DX气的成分对黑化膜品质的影响。计算分析了成分不同的煤气在制成DX气时的成分变化。同时还分析了黑化工艺和黑化设备对煤气成分波动的适应性,及在生产实践中改变DX气制气时的煤气空气对黑化膜质量的影响。     

Off-Optimum Cure of Aerospace Epoxy Adhesives

Four epoxy film adhesives used in aircraft manufacture and repair have been examined to establish the effect of deviation from the cure cycle specified by the manufacturer. In addition to the variation of the cure cycle, two surface preparations of the aluminium adherends (chromic acid etch or grit blast followed by silane treatment) were evaluated. Thermal analysis was used to examine the cure envelope of the adhesive, and its extent of cure and glass transition temperature. The adhesive properties were assessed by shear strength (in both single lap joints and in Iosipescu configuration), durability (Boeing wedge test) and chemical resistance to selected aggressive fluids. The sensitivity of the performance of a particular adhesive to offoptimum cure conditions depends on its composition and needs to be determined, not predicted.     

Cure reaction for modified diallylbisphenol A/diaminodiphenylsulfone/bismaleimide

The glass‐transition temperature as a function of curing conversion for a modified diallylbisphenol A/diaminodiphenylsulfone/bismaleimide (BMI) resin was investigated at different temperature regimes and modeled using a modified Di Benedetto equation. Although the relationship between the glass‐transition temperature and conversion of the BMI system conforms to the Di Benedetto equation for α < 0.6 and at lower cure temperatures, at higher cure temperatures the results deviated significantly from the equation; thus, it was an inadequate model for the system. Fourier transform IR analysis showed that the major crosslinking reactions did not occur during cure for the modified BMI at and below 150°C. However, as the cure temperature was increased, the crosslinking reactions responsible for 3‐dimensional network structures became more dominant. At 190°C the C? N? C_stretch vibration of the uncured maleimide ring converted into succinimide rings in the curing process. Simultaneously, a decrease was observed for the absorbance bands of ? C? H_bending (maleimide). The higher cure temperatures induced a significantly faster initial crosslinking rate and also resulted in a shorter period of time after which further crosslinking was retarded, because the increase in the crosslinks also physically slowed further crosslinking activity. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 227–235, 2002