应用^29Si和^27Al MASNMR谱研究粘土结构

用＾２９Ｓｉ和＾２７Ａｌ ＭＡＳＮＭＲ谱研究粘土矿物，可测定其化学位移及面四体、八面体相对含量和粘土中伴生矿物的含量，得出高岭石、伊利石结晶度和峰宽关系。     

碾压混凝土坝施工机械配套方案的模糊优选

本文针对碾压混凝土坝施工机械配套方案的多样性，复杂性和选择方案时证券条件的模糊性提出采用模糊优选方法和层次分析法相结合，对多个待选方案进行综合评价和优选。论述了评价系统的建立，评价指标隶属度的确定，以及用层次分析法确定各评价指标间的相对权重。并介绍了模糊优选程序及一个应用实例。     

TiCu金属玻璃及其氢化物的结构

氢可用来作为探测金属玻璃结构信息的探针。从氢化和未氢化的TiCu金属玻璃的径向分布函数实验结果表明,在8.5×10~3Pa H_2和80℃条件下氢化,根据测得的原子最近邻间距推知,钛原子和铜原子的最近邻间距有显著变化。由此可认为,氢主要占据由钛原子和铜原子组成的四面体间隙位置。     

Computing depth maps from descent images

In the exploration of the planets of our solar system, images taken during a landers descent to the surface of a planet provide a critical link between orbital images and surface images. The descent images not only allow us to locate the landing site in a global coordinate frame, but they also provide progressively higher-resolution maps for mission planning. This paper addresses the generation of depth maps from the descent images. Our approach has two steps, motion refinement and depth recovery. During motion refinement, we use an initial motion estimate in order to avoid the intrinsic motion ambiguity. The objective of the motion-refinement step is to adjust the motion parameters such that the reprojection error is minimized. The depth-recovery step correlates adjacent frames to match pixels for triangulation. Due to the descending motion, the conventional rectification process is replaced by a set of anti-aliasing image warpings corresponding to a set of virtual parallel planes. We demonstrate experimental results on synthetic and real descent images.Received: 7 November 2002, Accepted: 13 September 2004, Published online: 25 February 2005 Correspondence to: Clark F. Olson     

Texture evolution of “Amaretti” cookies during storage

The results of a study on texture evolution during 35 days of storage of amaretti, a typical Italian cookie, packaged in two different ways are reported. Amaretti cookies were wrapped in polyvinylchloride (PVC) film or aluminium foil (ALL), to simulate two different permeability conditions and stored at controlled temperature and humidity. Evolution of texture (such as hardness) and a_w were tested instrumentally by a texture analyser and a hygrometer, respectively. Texture was assessed by a cut and puncturing test. Indices for hardening were the area under the curve (N mm) and gradient (N/mm) for the puncturing test and maximum force (N) for the cut test. Both textural tests showed significantly higher hardening of PVC cookies, compared to the ALL cookies. The latter retained good sensorial properties at the end of the storage period, although their internal structure changed from soft and moist to mealy, while the PVC cookies were no longer edible only 10 days after baking. a_w values decreased and increased in PVC and ALL lots, respectively. The results suggest that hardening may be explained by water loss in PVC and moisture redistribution in ALL.     

Effect of strain history on craze microstructure

Crazes formed under a constant tensile strain in polystyrene (PS) have a dense network of fibrils with an extension ratio $\text{λ ? 4}$, but a midrib of higher λ forms by drawing fibrils from the craze-matrix interface in the high stress region just behind the craze tip. Stepwise increases in tensile strain during craze growth should thus produce layers of fibrils of different λ, which can be revealed by transmission electron microscopy (TEM) of crazes in stepwise strained PS films. When the time interval between strain increments of 0.5–1% is one minute, TEM images show ‘ridges’ of lower λ fibrils, corresponding to the position of the craze-matrix interface at the time of the strain increments. The ridges appear to be the analogue of the bulge remaining on a macroscopic fibre which has been allowed to stress age by stress relaxation before resuming drawing and imply that rapid stress ageing must occur near rthe craze-matrix interface so that more material is drawn into the craze in preference to increasing the λ of the existing fibrils.     

金属结构焊缝的疲劳设计

本文讨论分析了目前金属结构焊缝的设计方法，介绍了焊缝疲劳设计的方法及公式，提出了提高金属结构焊缝疲劳强度的一些措施。     

特殊弹簧合金3YC42组织的电镜研究

对我国自行研制的新型高弹性合金3YC42的不同工艺状态的组织进行了透射电镜研究，为合金设计与加工工艺的优化提供了理论与实验基础，证实了保证航天工程用特殊弹簧部件全面服役性能质量的材料设计方法的成功。