基于关键帧的三维人脸皱纹动画

表现人脸的皱纹特征是提高人脸动画真实感的重要因素之一,文章提出了一种基于关键帧的皱纹动画方法,使用高度图、法线图和MPEG-4人脸运动参数描述皱纹动画关键帧,通过对高度图、法线图插值生成皱纹动画中间帧。所提方法对人脸模型网格复杂度要求不高,且合成的皱纹动画具有真实感强和实时性高的特点。     

圆形构筑物周边土工膜沉降时的褶皱产生机理及分析模型

基于传统薄膜理论建立了下卧土体沉降作用下圆形构筑物周边土工膜受力变形的分析模型,发现在下卧土体沉降作用下圆形构筑物周边土工膜中将产生褶皱,并揭示了其产生机理。进一步通过引入"可变泊松比"概念并基于褶皱薄膜理论建立了褶皱区与张拉区土工膜受力变形的分析模型,分析了下卧土体沉降大小、上覆土压力、土工膜界面强度、圆形构筑物半径及土工膜抗拉刚度对土工膜褶皱程度与受力变形大小的影响。结果表明下卧土体沉降越大、圆形构筑物半径越小,则褶皱程度及土工膜最大应变越大。最后提出了工程上控制土工膜褶皱和最大应变与张力的几点工程措施。     

Design of Strain‐Limiting Substrate Materials for Stretchable and Flexible Electronics

Recently developed classes of electronics for biomedical applications exploit substrates that offer low elastic modulus and high stretchability, to allow intimate, mechanically biocompatible integration with soft biological tissues. A challenge is that such substrates do not generally offer protection of the electronics from high peak strains that can occur upon large‐scale deformation, thereby creating a potential for device failure. The results presented here establish a simple route to compliant substrates with strain‐limiting mechanics based on approaches that complement those of recently described alternatives. Here, a thin film or mesh of a high modulus material transferred onto a prestrained compliant substrate transforms into wrinkled geometry upon release of the prestrain. The structure formed by this process offers a low elastic modulus at small strain due to the small effective stiffness of the wrinkled film or mesh; it has a high tangent modulus (e.g., >1000 times the elastic modulus) at large strain, as the wrinkles disappear and the film/mesh returns to a flat geometry. This bilinear stress–strain behavior has an extremely sharp transition point, defined by the magnitude of the prestrain. A theoretical model yields analytical expressions for the elastic and tangent moduli and the transition strain of the bilinear stress–strain relation, with quantitative correspondence to finite element analysis and experiments.     

精锻身管弹膛内壁成形圈纹缺陷机理研究

精锻身管弹膛成形是弹线膛同锻工艺中的重点和难点,弹膛内壁的成形质量直接关系到身管的精度和使用寿命,内壁产生圈纹是弹膛部位主要的成形缺陷。分析弹膛在锻造过程中身管内壁材料的受力特点和流动情况,结合有限元仿真和试验研究,通过圈纹产生的位置分析圈纹产生的原因,并建立相关的判断准则。对比弹膛内壁材料应力分析曲线和枪管锻打试验结果,发现环向圈纹的产生与内壁受压失稳有关,弹膛内壁在锻造过程中的切向应力分量超过临界值即出现失稳起皱现象。进一步研究发现,弹膛部位的锻造段锻造比达到临界值时,内壁产生的圈纹会在后续锻打过程中被重新压平,消除弹膛成形缺陷。结果表明：身管弹膛内壁在锻造过程中切向压应力超过约2 150 MPa即 发生失稳从而产生环向圈纹;压平弹膛内壁环向圈纹的锻造段锻造比阈值约为28.5%.     

Inspecting anisotropy in wrinkle recovery angle of woven fabric

In this paper, the anisotropic wrinkle recovery properties of plain and twill fabrics are explored by studying the variations of the wrinkle recovery angle with sample orientation angle. Orientation angle is the angle measured counterclockwise from the weft direction to the sample’s long axis, that is, the crease direction. This study focused on inspecting anisotropy in wrinkle recovery to find more effective test angles for different woven fabrics. A dynamic wrinkle recovery tester was used to measure the recovery angles of specimens automatically which were cut in various directions. The trend of plain fabrics shows that its recovery angle generally increases at first and then decreases with the increase in the orientation angle. The trend of twill fabrics differs in folding ways. The experimental results revealed that the wrinkle recovery angles of the woven fabrics had the lowest values near the orientation angles of 0° and 90°, i.e. the warp and weft directions, and therefore these two traditionally used directions in the standard test method did not best reflect the wrinkle recovery yielded from both warps and wefts. The diagonal direction (45°) was proven to be the optimal orientation angle for a balanced plain fabric, while the two orthogonal directions, i.e. the twill direction and its perpendicular direction, were found to be more relevant for a twill fabric. Optimal orientation angles used to test the wrinkle recovery angle of a woven fabric should be associated with its structure.     

高粱黑色素染色后棉织物性能测试与分析

以天然高粱黑色素上染棉织物,探讨了不同条件下染色对棉织物拉伸特性、剪切特性、弯曲特性、压缩特性及表面特性的影响,以及对折皱回复角及毛效的影响。结果表明:高粱色素染色可提高织物柔软性、弹性、活络性及抗形变能力,降低织物粗糙度,但同时丰满感、抗剪切变形能力、折皱回复角、毛效有所降低。     

壳聚糖双胍盐酸的合及其在羊毛织物上多功能性的应用研究

利用壳聚糖和双氰胺成功地合成了一种壳聚糖双胍盐酸盐(CGH),对合成反应条件进行了讨论,并应用红外光谱确认了CGH的结构.将合成的CGH对羊毛织物进行处理,借助扫描电子显微镜SEM分析羊毛纤维整理前后的表面形态和结构,结果表明,羊毛织物经水溶性的CGH预处理后,可提高织物的吸湿性和抗皱性,再利用兰纳素活性染料进行轧染微波固色,可大大提高活性染料对羊毛织物的上染百分率.     

引返编织在羊毛衫设计中的应用

介绍了引返编织的概念及其编织方法.通过实验对比,就引返编织所形成的褶皱以及局部立体外观效果的编织方法进行了较为详尽地分析与研究.同时,从服装设计的角度,对引返编织形成的褶皱以及局部立体外观效果在羊毛衫设计中的应用进行了初步探讨,提出了引返编织在羊毛衫设计中具有功能性与装饰性2大功能的结论,为设计人员提供了更多的设计思路,对推进和提升毛衫产品的开发具有重要的现实意义.     

Investigation on the novel measurement for fabric wrinkle simulating actual wear

It is very important to measure fabric wrinkling objectively and accurately. However, the most commonly used measurements could not be employed to realistically evaluate and predict how fabric will resist wrinkle when worn on human body. In our previous study, an equipment of measuring fabric wrinkling that can simulate actual wear was proposed. In this paper, we conduct further investigation on the measurement for fabric wrinkle-simulating actual wear, including improving the equipment, validating its repeatability, and clarifying its more accurate relationship with the wrinkle recovery angle (WRA) method. Results show that the measuring repeatability of the method is much better than WRA method and fabric wrinkling in the warp and bias direction plays more important part than weft. Therefore, it is advisable that WRA of the bias should be increased, whose measurement stability is the best in the WRA method as well. Equations of Wrinkle Density (WD) with WRAs are established, which can be used to estimate wrinkling of clothes after actual wear only by several WRAs of fabrics, avoiding the tedious clothes making and trial work.