含湿相变粗糙多孔材质的热质耦合分形研究

多孔材质复杂的内部结构和含湿状态对传热和传质特性有着重要意义,其热质耦合传递过程广泛存在于能源开发和工程隔热等领域。不同于在多孔材质理想状态下对传热和传质特性的单方面分析,该文将孔道的分布参数、粗糙表面、含湿状态和相变等因素考虑进去,运用分形理论推导出了含湿相变粗糙表面多孔材质的渗流系数和耦合等效导热系数的表达式。结果表明,渗流系数与面积分形维数、含湿饱和度呈正相关,与相对粗糙度、迂曲分形维数呈负相关;耦合等效导热系数与渗流系数、相变量呈正相关,与相对粗糙度呈负相关。此外,结果还表明,相变量以及相变引起的气体膨胀压强差对热质耦合传递也有着重要影响。     

Effects of Cone Angles on Nonlinear Vibration Responses of Functionally Graded Shells北大核心CSCD

The nonlinear vibration responses of functionally graded materials (FGMs) shells with different cone angles under external loads were studied. Firstly, the Voigt model was employed to describe the physical properties along the thickness direction of FGMs conical shells. Then, the motion equations were derived based on the 1st-order shear deformation theory, the von Kármán geometric nonlinearity and Hamilton’s principle. Next, the Galerkin method was applied to discretize the motion equations and the governing equations were simplified into a 1DOF nonlinear vibration differential equation under Volmir’s assumption. Finally, the nonlinear motion equations were solved with the harmonic balance method and the Runge-Kutta method, and the amplitude frequency response characteristic curves of the FGMs conical shells were obtained. The effects of different material distribution functions and different ceramic volume fraction exponents on the amplitude frequency response curves of conical shells were discussed. The bifurcation diagrams of conical shells with different cone angles, as well as time process diagrams and phase diagrams for different excitation amplitudes, were described. The motion characteristics were characterized by Poincaré maps. The results show that, the FGMs conical shells present the nonlinear characteristics of hardening springs. The chaotic motions of the FGMs conical shells are restrained and not prone to motion instability with the increase of the cone angle. The FGMs conical shell present a process from the periodic motion to the multi-periodic motion and then to chaos with the increase of the excitation amplitude. © 2022 Editorial Office of Applied Mathematics and Mechanics. All rights reserved.     

环向加筋圆柱壳轴向不均匀冲击响应

对轴向不均匀冲击载荷下环向加筋圆柱壳的动力响应进行了研究,在考虑了壳体及加筋肋骨骨的剪切变形和转动惯性的情况下,运用Ｈａｍｉｌｔｏｎ原理推导出壳体－肋骨系统的运动方程,并且采用一种半解析有限差分法进行求解,着重探讨了加筋肋骨对环向加筋圆柱壳动力响应的影响。     

新型网壳节点的弹塑性分析及试验研究

简要介绍了一种广泛应用于各类意志支,双层网壳结构的新型承插式节点,在弹塑性理论分析的基础上,进行了一组单向拉,压试验研究,为今后在实际工程中推广这种新型节点提供了可靠依据。     

长序厚壳桂的硬化侵填体

经光学显微镜和扫描电子显微镜观察,发现长序厚壳桂导管分子中存在丰富的硬化侵填体,这种侵填体的发育与导管－薄壁组织细胞间纹孔口的大小无关,而与轴向薄壁组织和射线有关。     

我的几点意见——评论“关于狭义相对论的本质”一文

评论了“关于狭义相对论的本质”一文,实际上仍使用了狭义相对论的两个基本假设。     

任意复杂板壳类零件展开的算法实现

应用参数双三次样条曲面,将曲面片上的边界曲线"拉直",按面积相等的规则展成"平面片",再将这些平面片按其在曲面上的拓扑关系拼合而得到零件的展开图,这种方法与现有方法相比,适应性更广,适合于任意复杂曲面零件,又能与曲面描述方法很好地结合,便于开发计算机辅助设计系统,在工程技术中具有较大的应用价值.     

一种新的生物光学材料——嗜菌紫质的性质及应用

本文主要介绍一种光敏蛋白──嗜菌紫质的结构、性质及其适于光学应用的一些特点。简要综述了嗜菌紫质膜的制备、嗜菌紫质在膜中的定向以及对嗜菌紫质的化学和遗传学修饰。     

偶氮胭脂红B与血清蛋白质相互作用的光度法研究及其分析应用

在酸性介质中，偶氮胭脂红B（ABX）与蛋白质在室温下能迅速结合生成复合物，其最大吸收波长为570nm，比ABX红移了50nm。本文用光度法研究了该结合反应的最佳条件，并在此基础上建立了一个测定蛋白质的新方法。在570nm处各蛋白质的浓度至少在2.5～120mg/L范围内与吸光度成正比，对测定牛血清蛋白质（BSA）、人血清蛋白（HSA）及γ-球蛋白（IgG）的桑德尔灵敏度分别为0.173、0.173和0.199μg/cm^2。除阴阳离子表面活性剂外，基余大部分物质不干扰蛋白质的测定。可见方法具有选择性好、灵敏度高且快速、稳定的优点，用于尿液及人血清样品中总蛋白的测定，所得结果与考马斯亮蓝方法测得结果基本一致。     

Synthesis of Fullerene-Acrylamide Copolymer Nanoball and Its Lubrication Properties

A novel fuUerene-acrylamide copolymer was synthesized via radical polymerization. It is soluble in polar solvents such as water, dimethyl sulfoxide etc. The product was characterized by FTIR, UV-Vis and GPC. TEM analysis shows that the average particle diameter is about 46 nm. Four-ball tests show that the addition of a certain concentration of the fullerene copolymer to base stock (2 wt% triethanolamine and 0.5 wt% OPZ aqueous solution) can effectively raise the load-carrying capacity (PB value) and the antiwear ability. SEM analysis shows that the addition results in reducing diameter of wear scar and decreasing wear.