在线multicast数据传输网络中的一个优化问题

首先建立了数据传输网络选择的最小成本模型，给出了有效支撑树代表集的概念，并给出了一个时间复杂性为D(mlogen)的算法产生代表集。然后对静态数据传输问题和在线数据传输问题，分别给出了一个时间复杂性为D(mlogen)和O(m^2 mlogen)的多项式时间的算法。     

Monte Carlo simulation of gas phase polymerization of 1,3‐butadiene. Part II: Kinetics optimization and confirmation

Studies on the deactivations and initiations of gas phase polymerizations of 1,3‐butadiene have been achieved by Monte Carlo simulation. Initiation and deactivation control the reaction before and after the peak of the polymerization rate, respectively. The influence of polymerization temperature has been studied. Monte Carlo modeling of polymerization kinetics and mechanism was confirmed by the agreement of experimental data and simulation results of polymerizations run with a temporary evacuation of monomer. The balance of catalysts and active chains is established by both initiation and chain transfer reactions with cocatalyst, which causes a ‘pseudo‐stability’ stage. © 2003 Society of Chemical Industry     

Inhibition of radical polymerization in solvent‐based systems (security of solvent‐based radical polymerization of PSA‐acrylic in a plant reactor)

This article shows the influence of some chain‐transfer agents as inhibitors for acrylic solvent‐based polymerization. These chain‐transfer agents can offer significant advantages, as outlined below. The following chain‐transfer agents were studied to stop or slow down the polymerization process in the case of a runaway: n‐dodecyl mercaptan, trimethylolpropane‐trimercaptoacetate, phenothiazine, diphenylphenylen diamine, cuprum oxide, isopropanol, toluene, and carbon tetrachloride. Synthesized pressure‐sensitive adhesive based on acrylic polymers and containing 2‐ethylhexyl acrylate, methyl acrylate, and acrylic acid were used for the production of self‐adhesives with high cohesion. The polymerization was accomplished in ethyl acetate. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 1354–1357, 2003     

无机阻燃剂高聚合度聚磷酸铵的研制

以五氧化二磷、磷酸铵盐、尿素为原料、氨气为保护气,制备了高聚合度聚磷酸铵无机阻燃剂。考察了五氧化二磷、磷酸铵盐、尿素的用量和反应温度对聚磷酸铵平均聚合度的影响。采用端基滴定法测定了聚磷酸铵的聚合度,并用X射线衍射(XRD)法表征了聚磷酸铵的晶体结构,同时测定了聚磷酸铵的粒度和溶解度。实验结果表明,制备聚磷酸铵的最佳反应条件为:n(磷酸氢二铵)∶n(五氧化二磷)∶n(尿素)=1∶1∶0.3,反应温度280~300℃,反应时间40m in,热处理温度250~280℃,热处理时间110m in。在此条件下制备的聚磷酸铵的平均聚合度大于600,平均粒径直径小于50μm,在水中的溶解度小于0.4g;XRD表征结果表明,所合成的物质为Ⅱ型聚磷酸铵。     

水溶液全循环法尿素装置中压分解"三种工艺"的比较

以生产数据结合理论计算的方法系统地比较、分析了水溶液全循环法尿素装置中中压分解“三种工艺”的热能利用、甲铵分解率、总氨蒸出率、水平衡量、一分加热器生产能力等方面的情况，提出应用和配置预分离-预蒸馏工艺的方法，评论该工艺在水溶液全循环法中的地位和作用。     

Transport of a surface-applied corrosion inhibitor in cement paste and concrete

Surface-applied corrosion inhibitors are a kind of repair material and usually contain an aminoalcohol and a component forming a salt with the aminoalcohol. According to the manufacturers, this type of inhibitor penetrates very rapidly into concrete; however, the transport mechanisms have not been sufficiently investigated so far. The major part of the study therefore focused on the transport of the ingredients of an inhibitor in cement paste and concrete, which contained an aminoalcohol and a phosphorous compound. It has been shown that the latter forms an insoluble calcium salt in the environment of cement and precipitates quantitatively. It is thus unable to penetrate from the outside into the alkaline concrete zone and cannot develop its inhibiting effect there. The aminoalcohol, on the other hand, is not bound by cement, but remains largely dissolved in the pore liquid, thus providing optimal conditions for high mobility. The analysis of the transport mechanisms involved has revealed that diffusion in the dissolved state is by far the most efficient transport mechanism. While basically the transport of the aminoalcohol via the gaseous phase is possible, it does play an inferior role only. Surprisingly, the substance had hardly been absorbed by concrete by capillary suction, but at first remained close to the concrete surface.     

合成丁苯嵌段共聚物的影响因素

采用负离子溶液聚合方法制备了丁苯嵌段共聚物，研究了引发剂、活化剂、偶合剂、终止剂对聚合产物性能的影响。     

乙烯基硅氧烷改性苯丙乳液的研究

在苯乙烯 -丙烯酸酯乳液共聚反应后期 ,加入少量乙烯基硅氧烷 ,制得改性苯丙乳液 ,通过红外光谱初步确定了聚合物结构。研究了反应温度、反应时间、有机硅加入方式、乳化剂用量等因素对反应进程、乳液稳定性及涂膜性能的影响。     

聚甲亚胺改性尼龙6复合材料的等温结晶动力学

采用差示扫描量热法（DSC）对聚甲亚胺（PAM）/尼龙6复合材料等温结晶过程进行了研究。结果表明，PAM的加入使得基体的结晶速率增大，尤其是当含量为5%时，半结晶期明显减少。研究还发现，该体系的等温结晶过程完全可以用Avrami方程来描述，各试样的Avrami指数均在2-3之间，表明Avrami指数，球晶生长方式基本不受聚甲亚胺加入的影响。基体中原位形成的聚甲胺微纤起到了诱导结晶的作用，使得基体的结晶速率加快，但随着微纤含量的增加，由于分散性能变差而使得诱导结晶的能力减弱，表现为结晶速率又有所降低。     

高分子表面活性剂对超声辐照下苯乙烯乳液聚合的影响

在超声辐照引发苯乙烯乳液聚合中加入一种新型的以羧甲基纤维素为基础的高分子表面活性剂(CMC—A9)，讨论了高分子表面活性剂对反应动力学的影响。实验表明，超声辐照下初级自由基并非由通常认为的高分子表面活性剂产生，而是十二烷基硫酸钠在超声辐照下断裂，产生自由基。通过对反应动力学的研究，发现超声辐照下乳液聚合机理不同于常规乳液聚合，聚合反应过程只有两个阶段，即加速期和减速期，不存在恒速期。加入CMC—A9高分子表面活性剂，可以在较短的时间内和较低的超声功率下达到较高的单体转化率。