Study of the miscibility and crystallization behavior of poly(ethylene oxide)/poly(vinyl alcohol) blends

The miscibility and crystallization behavior of poly(ethylene oxide)/poly(vinyl alcohol) (PEO/PVA) blends were investigated by differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), and polarizing optical microscopy. Because the glass‐transition temperature of PVA was near the melting point of PEO crystalline, an uncommon DSC procedure was used to determine the glass‐transition temperature of the PVA‐rich phase. From the DSC and DMA results, two glass‐transition temperatures, which corresponded to the PEO‐rich phase and the PVA‐rich phase, were observed. It was an important criterion to indicate that a blend was immiscible. It was also found that the preparation method of samples influenced the morphology and crystallization behaviors of PEO/PVA blends. The domain size of the disperse phase (PVA‐rich) for the solution‐cast blends was much larger than that for the coprecipitated blends. The crystallinity, spherulitic morphology, and isothermal crystallization behavior of PEO in the solution‐cast blends were similar to those of the neat PEO. On the contrary, these properties in the coprecipitated blends were different from those of the neat PEO. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 1562–1568, 2004     

Comprehensive assessment on dynamic roof instability under fractured rock mass conditions in the excavation disturbed zone

The damage process of fractured rock mass showed that the fracture in rocks induced roof collapse in Yangchangwan Coal Mine,China.The rock mass was particularly weak and fractured.There occurred 6 large-scale dynamical roof falls in the excavation disturbed zone (EDZ) with the collapsing volume of 216 m3.First,the field detailed geological environment,regional seismic dy-namics,and dynamic instability of roadways were generally investigated.Second,the field multiple-index monitoring measurements for detecting the deep delamination of the roof,convergence deformation,bolt-cable load,acoustic emission (AE) characteristic pa-rameters,total AE events,AE energy-releasing rate,rock mass fracture,and damage were arranged.Finally,according to the time-space-strength relations,a quantitative assessment of the influence of rock-mass damage on the dynamic roof instability was accomplished.     

争创国内一流工程咨询企业集团——瑞和安惠项目管理集团有限公司董事长宋蕊访谈录

国家投资体制改革以来,我国工程咨询行业发展迅速,涌现了一大批工程咨询企业,国家发展改革委刚刚发布的《工程咨询业2010-2015年发展规划纲要》中指出要“壮大行业实力,培育一批品牌优势突出、具有国际竞争力的工程咨询集团。”工程咨询企业发展的现状如何？近日,带着这一问题,我们来到河北省石家庄市走访了瑞和安惠项目管理集团,对该公司董事长宋蕊女士（以下简称宋蕊）进行了采访。     

兴滇咨询，与中国工程咨询业一起成长——访昆明兴滇技术经济咨询有限公司董事长龚建平

在祖国的西南边陲云南省,有一家叫昆明兴滇技术经济咨询有限公司（以下简称兴滇公司）的综合性工程咨询单位,它在短短的23年发展进程中,创下了许多个全省第一。第一家成立的综合性工程咨询机构,第一家拿到国家甲级工程咨询资质的咨询单位,第一家完成股份制改造、与政府脱钩的咨询企业,第一家成为中国工程咨询协会会员和国际咨询工程师联合会（FIDIC）成员协会会员的咨询公司。     

打造高原咨询铁军——访“全国抗震救灾英雄集体”青海省工程咨询中心主任张贺全

本刊记者：张贺全主任,您好!在8月19日召开的青海玉树全国抗震救灾总结表彰大会上,青海省工程咨询中心（以下简称青咨中心）荣获“全国抗震救灾英雄集体”光荣称号,受到中共中央、国务院、中央军委的隆重表彰,我代表《中国工程咨询》杂志及本刊读者向您及贵中心表示热烈的祝贺!你们获得“全国抗震救灾英雄集体”最高荣誉称号,     

Synthesis and characterization of CdS nanocrystals embedded on solid electrolyte films

In this article nano‐sized CdS crystal embedded in a PEO matrix was successfully prepared by a complex transformation method that is universal for preparing nanosized compounds containing transition metals. The size of embedded CdS particles was in the nanoscale from 2 to 10 nm determined by X‐ray diffusion. The nanosized CdS displayed the expected blue shift of the onset absorbance in the UV spectrum. The amount of blue shift depends upon the dipping time of the PEO–cadmium complex film in a sodium sulfide solution as well as its concentration. The most effective means for adjusting the size of CdS nanocrystals is to change the ratio of the oxygen along with the PEO chain to the cadmium ion in the complex film. The alkali salt in the film would contribute to the conductivity of the composite film. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 1263–1268, 2002; DOI 10.1002/app.10459     

三维编织复合材料编织工艺过程仿真研究

总结了四步编织工艺的运动规律。对纱线的空间坐标进行三次B样条曲线拟合得到拟合坐标;设计实现了纱线实体的静态模型算法,根据拟合坐标得到纱线空间网格坐标并建立了纱线实体的静态模型;实现了纱线轨迹的动态展示以及实体生成过程的动态展示;构建了GUI界面并编译成了可脱离Matlab环境的独立运行程序。     

Factors influencing magnetic polymer microspheres prepared by dispersion polymerization

Magnetic iron oxide (Fe₃O₄) was prepared by a coprecipitation method. Core–shell composite magnetic polymer microspheres with carboxyl groups were synthesized by the dispersion polymerization of styrene and acrylic acid in the presence of magnetic oxide, and dibenzoyl peroxide was used as an initiator. The synthesized magnetic polymer microspheres were characterized with X‐ray diffraction, transmission electron microscopy, scanning electron microscopy, Fourier transform infrared spectroscopy, and so forth. The results indicated that the product was single‐phase Fe₃O₄, and its average size was about 10 nm. The configuration of the microspheres, which contained carboxyl groups, was spherical, and the average size was about 2 μm. The results of vibrating sample magnetometry tests showed that the magnetic powders produced by different surfactants had different saturation magnetizations. When poly(ethylene glycol) with a weight‐average molecular weight of 4000 was used as a surfactant, the saturation magnetization of the samples reached 69.2 emu/g. The factors that affected the shape, magnetism, size, and distribution of the microspheres were also studied. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Virtual Model Reduction-based Control Strategy of Planar Three-link Underactuated Manipulator with Middle Passive Joint

This paper presents a position control strategy for a planar active-passive-active (APA) underactuated manipulator with second-order nonholonomic characteristics. According to the structural characteristics of the planar APA system, we divide the system into two parts: a planar virtual Pendubot (PVP) and a planar virtual Acrobot (PVA). For the PVP, we mainly fulfill the target angle of the first link, which is calculated through the geometry method, and make the system stable. In this stage, via keeping the states of the third link being zero, the system is reduced to the PVP. Meanwhile, we design an open-loop control law based on the nilpotent approximation (NA) model of the PVP to make the second link stable and the first link stabilize at its target angle. Then, the planar APA system is reduced to a PVA with all links’ angular velocities being zero. For the PVA, we mainly realize the other two links’ target angles obtained via the particle swarm optimization (PSO) algorithm. Thus, the control objective of the planar APA system is achieved. Finally, above control strategy is verified by simulation results.