Sparse Localized Decomposition of Deformation Gradients

Sparse localized decomposition is a useful technique to extract meaningful deformation components out of a training set of mesh data. However, existing methods cannot capture large rotational motion in the given mesh dataset. In this paper we present a new decomposition technique based on deformation gradients. Given a mesh dataset, the deformation gradient field is extracted, and decomposed into two groups: rotation field and stretching field, through polar decomposition. These two groups of deformation information are further processed through the sparse localized decomposition into the desired components. These sparse localized components can be linearly combined to form a meaningful deformation gradient field, and can be used to reconstruct the mesh through a least squares optimization step. Our experiments show that the proposed method addresses the rotation problem associated with traditional deformation decomposition techniques, making it suitable to handle not only stretched deformations, but also articulated motions that involve large rotations.     

Polyline‐sourced Geodesic Voronoi Diagrams on Triangle Meshes

This paper studies the Voronoi diagrams on 2‐manifold meshes based on geodesic metric (a.k.a. geodesic Voronoi diagrams or GVDs), which have polyline generators. We show that our general setting leads to situations more complicated than conventional 2D Euclidean Voronoi diagrams as well as point‐source based GVDs, since a typical bisector contains line segments, hyperbolic segments and parabolic segments. To tackle this challenge, we introduce a new concept, called local Voronoi diagram (LVD), which is a combination of additively weighted Voronoi diagram and line‐segment Voronoi diagram on a mesh triangle. We show that when restricting on a single mesh triangle, the GVD is a subset of the LVD and only two types of mesh triangles can contain GVD edges. Based on these results, we propose an efficient algorithm for constructing the GVD with polyline generators. Our algorithm runs in O(nNlogN) time and takes O(nN) space on an n‐face mesh with m generators, where N = max{m, n}. Computational results on real‐world models demonstrate the efficiency of our algorithm.     

谈陶瓷材料对草坪灯的介入

陶瓷与自然有着天然的联系,能带给人们回归自然的审美情趣。陶瓷材料制作的灯具以其自然多变的机理、色调和形 状,比其他材料的灯具更易与景现环境融为一体。本文通过对草坪灯现状的分析,根据陶瓷材料的特点,提出陶瓷介入 草坪灯,对丰富室外环境审美客体有着积极的意义。     

固体酸SO4(2-)/Nb2O5催化合成尼龙酸二异丁酯

研究了SO4^2-／Nb2O5作为催化剂催化合成尼龙酸二异丁酯的反应。通过正交试验确定了最佳反应条件：酸醇物质的量比为1：2．5，催化剂为反应物总量的0.35％，反应回流2．0h，在此条件下酯化率可达97．8％。     

A study on carbon coating to silicon and electrochemical characteristics of Si-C/Li cells

The aim of this paper is to study the electrochemical behavior of Si-C material synthesized by heating a mixture of silicon and polyvinylidene fluoride (PVDF) in the ratios of 5, 20, and 50 wt%. The particle size of the synthesized material was found to be increased with increase in the PVDF ratio. The coexistence of silicon with carbon was confirmed from the XRD analysis. A field emission scanning electron microscope (FESEM) study performed with the material proved the improvement in coating efficiency with increase in the PVDF ratio. Coin cells of the type 2025 were made by using the synthesized material, and the electrochemical properties were studied. An electrode was prepared by using the developed Si-C material. Si-C|Li cells were made with this electrode. A charge|discharge test was performed for 20 cycles at 0.1 C hour rate. Initial charge and discharge capacities of Si-C material derived from 20 wt% of PVDF was found to be 1,830 and 526 mAh|g, respectively. Initial charge/discharge characteristics of the electrode were analyzed. The level of reversible specific capacity was about 216mAh/g at Si-C material derived from 20 wt% of PVDF, initial intercalation efficiency (IIE), intercalation efficiency at initial charge/discharge, was 68%. Surface irreversible specific capacity was 31 mAh/g, and average specific resistance was 2.6 ohm * g.     

在役加氢反应器材料损伤分析

基于随加氢反应器运行 5a的试验试块 ,研究了加氢反应器运行 5a后筒体材料 2 .2 5Cr 1Mo钢的损伤。进行了化学成分分析、拉伸和冲击试验、脱氢和脱脆试验以及断口形貌分析。结果表明 :反应器运行 5a后筒体母材及其焊缝金属的拉伸性能未发生明显变化 ,而冲击韧性明显降低 ,且焊缝金属损伤程度较母材严重。经分析 ,材料的损伤主要是加氢反应器长期使用过程中高温回火所致     

圆盘反应器中的PET缩聚过程

利用薄膜实验研究了PET缩聚过程反应和传质规律 ,建立了链增长、链降解反应动力学模型和泡沫脱挥时的传质速率方程 ;通过冷模实验研究了圆盘反应器中PET的混合、流动、成膜、膜表面更新以及传质规律 ;综合了反应和反应器研究结果 ,建立了圆盘反应器中的PET缩聚过程模型 ,对圆盘反应器中的PET缩聚过程进行了仿真分析 ,考察了温度、压力、停留时间、转速、催化剂浓度、负荷大小等各种因素的影响     

振动剪切作用下聚合物熔体的非仿射网络结构模型 Ⅱ．非仿射网络结构模型

假设聚合物熔体的缠结网络形变是非仿射的，运用瞬态网络结构原理，采用在本课题第一部分^[1]中所建立的动态速率方程，并对上随体Maxwell本构方程加以修正来建立一个非仿射网络结构模型，利用这一模型来研究振动剪切作用下LDPE熔体的流变行为，研究表明，随着应变振幅和频率的增加，LDPE熔体的剪切应力也增加，同时指出了非仿射网络结构模型的精确变比仿射结构模型有较大提高，这表明在振动力场作用下，网络形变发生了非仿射形变，因此在建立振动力场作用下聚烯烃熔体本构方程时，不能假设其网络是仿射形变的。     

聚氨酯预聚体——可聚合乳化剂用于MMA乳液聚合动力学及聚合稳定性研究

将合成的聚氨酯预聚体可聚合乳化剂（APUA）用于甲基丙烯酸甲酯（MMA）乳液聚合体系中，研究了不同引发剂体系和乳化剂对聚合体系的聚合稳定性和动力学影响，并与SDS乳化剂进行了对照。结果显示，用油溶性引发剂（AIBN）和水溶性引发剂（K2S2O8）都能引发该体系的聚合反应，而且聚合速率和转化率都相当高。用AIBN作引发剂时，APUA和SDS两种乳化所对应的动力学曲线不同，但APUA比SDS的聚合速率大得多，其分别类似于微乳液聚合（miniemulsion)和微悬浮聚合（microsuspention)，且聚合过程中会产生一定的凝胶。当乳化剂APUA用量适合时，凝胶量极少，聚合体系是稳定的；而当用K2S2O8作引发剂时，两乳化剂对应动力学曲线相似，聚合过程不产生凝胶。但当引发剂用量较大并以APUA作乳化剂时，在聚合过程中会出现全部粒子突然粗化现象，而以SDS作乳化剂没有出现这一现象。     

Ways of strengthening biodegradable soy‐dreg plastics

Biodegradable plastics (GSD) based on soy dreg (SD) were prepared by compression‐molding, with glycerol as the plasticizer and glutaraldehyde (GA) as the cross‐linker. The structure and properties of the GSD sheets were investigated by Fourier‐transform infrared spectroscopy (FTIR), X‐ray diffraction (XRD), differential scanning calorimetry (DSC), dynamic mechanical thermal analysis (DMTA), scanning electron microscope (SEM), and tensile test methods. The results indicate that when GA content was 6.8%, the tensile strength (σ_b) of the sheet reached the maximum value of 14.5 MPa. Moreover, the strength and water resistance of the sheets coated with castor‐oil‐based polyurethane/nitrochitosan interpenetrating network (IPN) coating were significantly enhanced to 24.6 MPa in the dry state and 9.8 MPa in the wet state. Simultaneously, the test of biodegradability of the GSD sheet in a mineral salts medium containing microorganisms and agar proved that GSD could be fully biodegradable. This work has provided a novel way to utilize low‐cost SD to prepare biodegradable plastics. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 422–427, 2003