衣架式机头口模设计公式的修正探讨

基于表征值方法和熔体等压线平行于模唇这一流动模型,对衣架式机头口模进行了流动分析,并发现了文献[1]提出的口模设计公式中的一个缺陷,即计算的扇形狭缝区域与歧管发生了分离,针对该缺陷给出了修正公式。     

常减压蒸馏装置配剂方法比较

对常减压装置的三种配剂方法进行分析比较，从而选出经济、合理的配剂方法。     

ENR／CSM的自硫化研究

研究在没有任何硫化剂的情况下环氧化天然橡胶（ＥＮＲ－５０）和氯磺化聚乙烯（ＣＳＭ－４０）共混物的自硫化，以及共混比、填料品种及用量、间苯撑双马来酰亚胺与马来酸酐等活性剂、硫化温度和时间对交联程度和性能的影响。结果表明ＥＮＲ／ＣＳＭ共混体可以产生自硫化；共混比为５０／５０时交联密度最大，性能最佳，炭黑和白炭黑对该体系有好的补强作用，但白炭黑的补强作用比炭黑的好；间苯撑双马来酰亚胺及马来酸酐能活化自硫化体系；延长硫化时间及提高硫化温度均可增加交联作用，该自硫化体系没有返原现象。     

Effects of the o‐aromatic ring in the molecular chain on the properties of polyester polyols

A series of liquid polyester polyols from adipic acid (AA), phthalic anhydride (PA), ethylene glycol, propanediol‐1,2, and trihydroxymethylpropane, varying in the molar ratio of PA to AA, were prepared. The effects of the o‐aromatic ring in the molecular chain, which came from PA, on the viscosity, glass‐transition temperature, and thermal degradation temperature of the polyester polyols were studied with viscometry, differential scanning calorimetry, and thermogravimetry. The intrinsic viscosity and glass‐transition temperature increased with the concentration of the o‐aromatic ring increasing. The temperature of the maximum thermal degradation rate for aliphatic polyester polyols was 434.20°C. Two steps of thermal degradation were found when there were o‐aromatic rings in the molecular chain. One thermal degradation temperature was 358.36–360.48°C, and the other was 412.85–427.18°C. Polyester polyols with o‐aromatic rings had higher stability at lower temperatures (<240.00°C). However, aliphatic polyester polyols had higher stability at higher temperatures (300.00–480.00°C). The activation energy and order of degradation were calculated from thermogravimetric curves. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 1617–1624, 2002     

工业变换炉最佳催化剂粒度

本文在建立数学模型的基础上，用计算机模拟变换炉的操作工况，考察改变催化剂粒度对经济效益的影响，从而得到工业变换炉催化剂颗粒最佳尺寸，开发了以经济效益为考察依据，工业反应器中催化剂颗粒最佳尺寸的计算方法。     

Copolymerization of trimethylene carbonate and 2,2-dimethyltrimethylene carbonate by rare earth calixarene complexes

Rare earth (Nd, Y, La) p-tert-butylcalix[n]arene (n=4, 6, and 8) complexes alone have been developed to catalyze random and block copolymerizations of trimethylene carbonate (TMC) and 2,2-dimethyltrimethylene carbonate (DTC). The random or block structure and thermal behavior of the copolymers have been characterized by SEC, NMR, DSC, XRD and PLM. Random copolymer with M_w of 14,100 and M_w/M_n of 1.36 was prepared by neodymium p-tert-butylcalix[6]arene complex under the conditions: [TMC+DTC]₀/[Nd]=400, 80 °C, 8 h. The reactivity ratios of TMC and DTC are measured to be r_TMC=4.68 and r_DTC=0.163, respectively. Random copolymerization could be well designed by the feeding ratio to prepare copolymers with controlled T_m and T_g. Only 8% TMC units in the polymer chain destroyed the crystallization of PDTC showing no T_m of the copolymer in the DSC analysis.     

云计算背景下软件企业创新的趋势

云计算是一种基于互联网的计算方式,通过这种方式,共享的软硬件资源和信息可以按需提供给计算机和其他设备,该技术是一种近些年来发展的新兴科技,同时在一定的程度之上遍布于软件企业的各个领域之中,引导着当前软件企业发展的方向.基于此,本文探讨了云计算背景之下软件企业创新的趋势.     

基于MMTD算法的粒子群的解

粒子群算法是一种寻找最优解的算法,该算法在寻找的过程中需要粒子所得的目前解具有判断力和记忆力.然而正是由于该算法中的粒子对当前的解具有判断力,这才能够使得粒子群中的粒子能够较快地找到最优解.粒子群中的粒子在求解过程中所得的结果可分为三种：优,中,差,这三种解的属性符合中介思想.然而MMTD的算法正是中介思想的一种应用,因此本文将MMTD算法在粒子群上进行应用,该算法能够对粒子群解的属性上做出判断.     

计算机网络的安全防范技术分析

近年来,随着我国科学技术的日益发展进步,计算机的应用越来越普及,在人们日常生活和工作中发挥着重要作用,影响着人们的生活质量和社会的发展。而且计算机的使用人群很广泛,不论是教师、公务员、医生或者农民、工人等等,都在逐渐接触它,无疑将是人类生存的重要助手。但正是如此,在使用计算机的过程中暴露了许许多多的问题,给人类带来了伤害,我们应该主动去防范,本文正是对此进行研究。     

Layered Mg-Al spinel supported Ce-Fe-Zr-O oxygen carriers for chemical looping reforming

A series of layered Mg-Al spinel supported Ce-Fe-Zr-O oxygen carriers were prepared for co-production of syngas and pure hydrogen via chemical looping steam reforming (CLSR). The presence of magnesium-aluminum layered double oxides (MgAl-LDO) significantly increases the specific surface area of the mixed oxides, reduces the particle size of CeO₂-based solid solution and promotes the dispersion of free Fe₂O₃. When reacting with methane, MgAl-LDO supported oxygen carrier shows much lower temperature for methane oxidation than the pure CeFe-Zr-O sample, indicating enhanced low-temperature reactivity. Among different Ce-Fe-Zr-O(x)/MgAl-LDO samples, the Ce-Fe-Zr-O(40 wt%)/MgAl-LDO sample shows the best performance for the selective oxidation of methane to syngas and the H₂ production by water splitting. After a long period of high temperature redox experiment, the Ce-Fe-Zr-O(40 wt%)/MgAl-LDO oxygen carrier still shows high activity for syngas generation. The comparison on the morphology of the fresh and cycled oxygen carriers indicates that the Mg-Al spinel support still forms a stable skeleton structure with high dispersion of active components on the surface after the long-term cycling, which contributes to excellent redox stability of the Ce-Fe-Zr-O(40 wt%)/MgAl-LDO oxygen carrier.