An eight‐node hybrid‐stress solid‐shell element for geometric non‐linear analysis of elastic shells

This paper presents eight‐node solid‐shell elements for geometric non‐linear analysis of elastic shells. To subdue shear, trapezoidal and thickness locking, the assumed natural strain method and an ad hoc modified generalized laminate stiffness matrix are employed. A selectively reduced integrated element is formulated with its membrane and bending shear strain components taken to be constant and equal to the ones evaluated at the element centroid. With the generalized stresses arising from the modified generalized laminate stiffness matrix assumed to be independent from the ones obtained from the displacement, an extended Hellinger–Reissner functional can be derived. By choosing the assumed generalized stresses similar to the assumed stresses of a previous solid element, a hybrid‐stress solid‐shell element is formulated. Commonly employed geometric non‐linear homogeneous and laminated shell problems are attempted and our results are close to those of other state‐of‐the‐art elements. Moreover, the hybrid‐stress element converges more readily than the selectively reduced integrated element in all benchmark problems. Copyright © 2002 John Wiley & Sons, Ltd.     

网壳结构内扩安装法施工内力特性分析

本文针对目前国内常用的网壳内扩安装法，全过程跟踪分析了构件在用内扩法安装期间的施工内力特性及其变化规律，得出了网壳结构设计计算必须考虑施工内力的影响等重要结论。     

Use of TNSAC in phosphate adsorption studies and relationships. Isotherm relationships and utility in the field

There is a need for developing low cost, easily and abundantly available, yet efficient, adsorbents for the removal of phosphates during the tertiary treatment of wastewaters. The tamarind nut shell activated carbon (TNSAC) prepared on a laboratory scale has been used to evaluate its performance for phosphate adsorption. This paper describes the laboratory production of this adsorbent material in its various forms, and discusses the effects of the TNSAC process variables (the unrinsed and rinsed forms of the TNSAC and the impregnation ratio) on its performance in adsorbing phosphate. The material has been shown to be a good alternative adsorbent. As much as 95% phosphate removal by the unrinsed TNSAC is possible in about 30 min under the test conditions. The phosphate adsorbing capacity is about two times higher for the unrinsed TNSAC in comparison to the rinsed TNSAC. The adsorption rates, however, transit to extremely low rates towards the end when equilibrium conditions could be attained in about 2 h contact time. The phosphate removal mechanics are adsorption and precipitation/ion exchange when unrinsed TNSAC is used, and adsorption alone for the rinsed TNSAC. The maximum phosphate removal is found to take place at an impregnation ratio of 1.0 for both forms of the TNSAC.     

新抗冲型ACR的合成与研究

采用种子乳液聚合法制备了含有PBA＼PMMA＼PS三种组分的丙烯酸酯类抗冲型改性剂ACR，在ACR的幔层结构中引入接枝剂甲基丙烯酸烯丙酯（ALMA）来完善幔层结构，从而实现核一壳之间良好的结合，用红外光谱（FTIR）和差示扫描量热法（DSC）对ACR的组成和结构进行表征。研究结果表明：由PBA＼PMMA＼PS三组分构成的ACR在抗冲击性能上要略优于由简单的PBA＼PMMA构成的ACR，苯乙烯单体（St）最多可以取代大约1／3壳层的甲基丙烯酸甲酯（MMA），甲基丙烯酸烯丙酯（ALMA）的引入对幔层结构的完善起了显著的作用。     

控制转炉炉壳蠕变变形

转炉采用镁碳砖炉衬后，炉壳温度急剧增加，炉壳的局部区域会发生永久变形。分析认为：炉壳的永久变形是由于蠕变变形引起，而不是塑性变形引起，给出了影响蠕变变形的因素，指出了控制炉壳蠕变变形的策略。     

Positively Thermo‐Sensitive Monodisperse Core–Shell Microspheres

In this paper, we report on a novel family of monodisperse thermo‐sensitive core–shell hydrogel microspheres that is featured with high monodispersity and positively thermo‐responsive volume phase transition characteristics with tunable swelling kinetics, i.e., the particle swelling is induced by an increase rather than a decrease in temperature. The microspheres were fabricated in a three‐step process. In the first step, monodisperse poly(acrylamide‐co‐styrene) seeds were prepared by emulsifier‐free emulsion polymerization. In the second step, poly(acrylamide) or poly[acrylamide‐co‐(butyl methacrylate)] shells were fabricated on the microsphere seeds by free radical polymerization. In the third step, the core–shell microspheres with poly‐ (acrylamide)/poly(acrylic acid) based interpenetrating polymer network (IPN) shells were finished by a method of sequential IPN synthesis. The proposed monodisperse core–shell microspheres provide a new mode of the phase transition behavior for thermo‐sensitive “smart” or “intelligent” monodisperse micro‐actuators that is highly attractive for targeting drug delivery systems, chemical separations, sensors, and so on.     

Preparation of core–shell type nanoparticles of diblock copolymers of poly(L‐lactide)/poly(ethylene glycol) and their characterization in vitro

Core–shell type nanoparticles of poly(L ‐lactide)/poly(ethylene glycol) (LE) diblock copolymer were prepared by a dialysis technique. Their size was confirmed as 40–70 nm using photon correlation spectroscopy. The ¹H‐NMR analysis confirmed the formation of core–shell type nanoparticles and drug loading. The particle size, drug loading, and drug release rate of the LE nanoparticles were slightly changed by the initial solvents that were used. The drug release behavior of LE core–shell type nanoparticles showed an initial burst during the first 12 h and then a sustained release until 100 h. The degradation behavior of LE block copolymer nanoparticles was divided into three phases: the initial rapid degradation phase, the stationary phase, and the rapid degradation phase until complete degradation. It was suggested that lidocaine release kinetics were predominantly governed by the diffusion mechanism in the initial burst phase and after that by both of the diffusion and degradation mechanisms. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 2625–2634, 2002     

向日葵壳水解-氧化-水解法制取草酸新工艺研究

研究了以植物纤维向日葵壳为原料，采用水解-氧化-水解法制取草酸（乙二酸）的新工艺。与用同类原料，其他方法制草酸相比，本工艺在提高产率，降低生产成本以及易于业化方面有很大突破。在H2SO4质量分数为70%，原料浸泡时间3h以上，m(HNO3):m（向日葵壳）=方面有很大突破，在H2SO4质量分数为70%，原料浸泡时间3h以上，m(HNO3):m(向日葵壳）=2.1:1.0；氧化-水解反应时间5h，反应温度65-70℃的条件下，草酸二水合物收率可达78.5%。     

模糊C-球壳聚类算法及其在血液细胞图像中的应用

文章从经典的模糊C均值算法开始通过改变其中相似性的度量形式，介绍了一种模糊C球壳聚类（FCSS）算法。在将该算法应用于细胞显微图像半径统计时，采用基于形态学的图像预处理措施，可以获得FCSS算法中有关原型模式的知识，加快收敛速度并避免随机初始化造成的局部极小问题。     

导汽箱产生长裂纹和大面积凹陷原因分析、处理及预防对策

对硫酸废热锅炉锅筒内自然循环的导汽箱产生长裂纹和大面积凹陷的原因作了分析，提出处理该缺陷的方法，确保了锅炉的安全运行，并提高了蒸汽的品质。