Polygonal Approximation of Digital Curves to Preserve Original Shapes

In this letter, we propose a novel polygonal approximation of digital curves that preserve original shapes. The proposed method first detects break points, which have two different consecutive vectors, and sets an initial dominant point set. The approximation is then performed iteratively by deleting a dominant point using a novel distance, which can measure both the distance and the angle acuteness. The experimental results show that the proposed method can preserve original shapes and is appropriate for various shapes, including slabsided shapes.     

An Alternative Thin-Plate Welding Technology Using Underwater Shock Wave

Abstract

In recent years, the size and weight of products dealt with in industry have been getting smaller and smaller and micro-bonding and micro-processing technology has become important. Underwater explosive welding can be an alternative bonding method for very thin materials, with a low formability, and which are difficult to bond together by traditional explosive welding methods. In this study, NiTi shape memory alloy and copper foil were welded in this new method. The welding process was simulated using the commercially available package LS-DYNA. The numerical simulation gave the deformations of the flyer and the base plate, and the pressure distribution during the welding process. Microstructure and fracture mechanism of the welded metals were evaluated. The bond interface of the welded metals showed a wavy morphology and the fracture mechanism of the composite laminate showed a predominantly quasi-cleavage with cleavage modes.     

Martensitic transformation of Ti50Ni30Cu20 alloy prepared by powder metallurgy

Phase transformation behavior of Ti50Ni30Cu20 shape memory alloys prepared by powder metallurgy is analyzed with respect to the duration of mechanical alloying. The processed blends were studied by differential scanning calorimetry and room temperature X-ray diffraction. The martensitic transformations evidenced by thermal scans are discussed in correlation with the relative phase content obtained from the refinement of the X-ray diffraction patterns.     

安钢高线粗中轧料型优化

安钢为克服高线粗中轧料型不合适易造成堆钢事故和成品头尾缺陷,将第6道料型尺寸由φ74 mm调整为φ72.5 mm,控制中轧的第12道和14道,小规格比原始料型稍小一些,大规格比原始料型稍大一些。料型优化后,φ10 mm及以下规格成品尺寸精度可达±0.1 mm,φ10 mm以上规格成品可达±0.15 mm,堆钢事故减少,头尾开裂率降低,成品头尾剪切圈数减少。主要经济指标成材率、有效作业率分别提高0.2%,5%。     

Ice Cream: Foam Formation and Stabilization—A Review

Ice cream has been studied from ingredients to process conditions, ice crystal formation to ice crystal growth, and ingredient selection to eating quality. One of the key aspects of ice cream is air cells, as formation and acceptance of ice cream rely on foam production and stabilization. Air cells in ice cream provide a unique structure that governs many of this product's keeping and eating qualities. The air cells are dependent upon ice cream mix composition (fat, protein, and surface active ingredients) as well as processing conditions (freezer shear force, hardening time, and storage temperatures). Optical, low-temperature scanning electron microscopy and transmission electron microscopy are applied to observe the morphology and size of air cells in ice cream. Air cells are crucial in forming the product and for eating quality and enjoyment.     

花纹钢板平整技术的开发及应用

介绍了一种新型平整技术——热轧花纹钢板缺陷修复技术的开发研究及应用效果。该技术的开发成功，解决了热轧薄规格花纹板浪型缺陷的修复问题，使产品质量明显提高。     

热轧薄板M形板廓缺陷研究

针对首钢京唐公司热轧板带生产中出现的M形板廓缺陷，从板形控制参数预设定和工作辊磨损辊型两方面分析了其产生原因，提出了简单、可行的改进措施，为同类机组技术改进提供了依据。     

Determining the keyhole geometry based on double-elliptic distribution of plasma arc pressure

The plasma arc pressure plays an important role in determining the keyhole formation and size. So it is of great significance to choose adaptive distribution mode of the plasma arc pressure for determining keyhole shape and size. In this study, through employing a double-elliptic distribution mode of plasma arc pressure, three-dimensional keyhole was numerically simulated. The unsymmetric feature of the keyhole inside the weld pool was described. The development of keyhole was demonstrated under different levels of welding current. The critical current required to form an open keyhole was obtained for the study cases.     

截流钢筋笼的稳定性及其计算方法

对实践中常用到的正六面体钢筋笼的稳定性从质量、形状以及有无垫底材料等方面进行了试验研究及工程实例验证。首次拟合提出了考虑其形状因素、河床糙度因素的正六面体钢筋笼止动流速和起动流速的计算公式,经试验验证具有较高的计算精度和实用性。此外,对四面体钢筋笼的稳定性也进行了试验研究,研究表明:四面体钢筋笼用于截流抛投这类止动问题的工程时,其止动稳定性明显优于相同质量的正六面体钢筋笼;而对于护底等起动问题的工程,两者起动稳定性差别不大。     

连续体形状优化中的几何表示及其敏度分析的研究

基于 B 样条函数与设计元概念,本文提出了连续体形状优化中颇为重要的几何描述法,并进而导出了所有的敏度计算公式.