基于端点与交点编码的矩形窗口多边形裁剪新算法

从矩形窗口裁剪任意多边形的本质特征出发,提出多边形各边端点编码技术。通过对多边形各边端点的一次及二次编码,可快速得到所有窗内边并舍弃绝大部分窗外边,还可快速判断该端点是内点还是外点。在已获取的窗内边、相交边的交点以及交点编码的基础上,可以得到正确的裁剪结果。同时考虑了矩形窗口与多边形相互包容的特殊情形。实验结果表明,新算法稳定可靠,实现了对任意凹凸多边形的裁剪,具有通用性强、算法简捷、裁剪效率较高的优点。     

任意二维图形的复杂窗口裁剪算法及其应用

本文提出了一种基于交点全搜索方式的复杂二维图形裁剪算法。该算法通过引入虚边，简化复连通区域为单连通多边形，能够有效地用于多个复连通区域之间的互相裁剪。算法经实际应用证明，具有较高的效率和很好的稳定性。     

IGES文件中裁剪曲面的剖析及正确显示方法

裁剪曲面是基本图形交换规范（IGES）的主要内容，详细介绍了IGES文件中裁剪曲面的定义格式。在开放图形库（OpenGL）环境中，要求裁剪曲面外环必须是逆时针的，内环是顺时针的才能得到正确的显示结果，给出了平面任意多边形走向判定算法用来调整内外环的走向。此外，还给出了曲面控制点和裁剪曲线中直线段的调整方法，提供的实例证明了算法的有效性。     

基于扫描带的任意多边形窗口线裁剪算法

提出了一个基于扫描带的任意多边形窗口线裁剪算法。首先确定裁剪窗口所有顶点对于被裁剪直线段的位置关系,然后生成过顶点的扫描线,及时修改由相邻两条扫描线所构成的扫描带结构数据,增加每条扫描带中位于被裁剪直线段左侧的裁剪窗口的边界线数。最后,根据左侧边界线数的奇偶性,确定相应直线段的可见性,并最终实现任意多边形窗口的直线段裁剪过程。     

基于圆柱面裁剪的多面体快速钻孔算法

提出一种高效的对凸多边形组成的多面体进行圆柱面裁剪的算法,并实现了多面体的快速钻孔。通过降维变换使多边形和圆柱面的拓扑关系判断、求交运算、孔内侧面的生成等简单化;离散圆弧的点链和多边形裁剪所余部分的顶点链构成近似平行线,据此设计了一个新算法对含孔或部分孔的凹面进行三角剖分;基于Z排序法利用离散圆弧的点构造孔的内侧面。实验及应用实例表明该算法能够满足参数化三维建模中快速建模的要求。     

2D图形引擎中的平面多边形内外点判别

在2D图形引擎中,可见性判定是一个非常重要的问题.通过屏幕裁剪,可以进一步减少多边形数目,减轻引擎的负担.因此,在屏幕裁减阶段完成的屏幕顶点与多边形的内外关系判断就显得很重要了.文章结合2D图形引擎的特点和流行的内外点判别算法给出了在DirectX平台上使用VC++实现的平面多边形内外点判断算法,并将其应用于实际的2D图形引擎中.程序验证表明,该算法能有效判定屏幕顶点与多边形的内外关系,且算法效率较高、简单易行.     

格网划分的双策略跟踪多边形裁剪算法

论文提出了一种高效稳定的多边形裁剪算法,算法支持带内环的平面简单多边形,同时也支持多边形的“并”和“差”等布尔运算.首先,设计了算法所需的数据结构;其次,基于直线扫描转换Bresenham算法原理提出了边网格划分的有效算法,并应用一个简单的方法避免不同网格内边的重复求交;最后,将交点分类为普通交点和顶交点,并针对这两类交点构造了不同的跟踪策略,在跟踪过程中交替、递归地应用这两个策略来确保算法处理特殊情况时的稳定性.与其它同类算法的比较表明,新算法具有更高的效率.     

确定任意多边形的核的算法

本文提出确定任意简单多边形Ｌ的核的算法，该算法的时间复杂性是Ｏ（ｌｎ）次乘法，其中ｎ是多边形的Ｌ的顶点数，ｌ是多边形Ｌ中凹点的数目。     

服装样片裁剪空行程路径的优化算法

服装样片裁剪空行程路径是影响裁床裁剪效率的重要因素,裁剪路径优化有助于提高裁剪效率。针对裁剪空行程优化问题,先构建了裁剪空行程路径的数学模型,结合遗传算法和蚁群算法的优势,提出了遗传蚁群混合算法优化裁剪空行程。算法先利用遗传算法的快速搜索能力建立蚁群算法的初始信息素分布,然后采用蚁群算法求精确解,最后建立仿真实验验证混合算法的可行性,与基本遗传算法相比,混合算法具有较优的全局优化性能。     

Cohen-Sutherland裁剪算法的改进

Cohen-sutherland裁剪算法对不与边框相交的线段进行裁剪时效率较高,而对与窗口边界有交点的线段裁剪效率低.为了提高线段裁剪效率,利用点与直线位置的关系性质,作者提出基于Cohen-Sutherland算法的裁剪思路并实现.与Cohen-Sutherland算法相比,新的算法提高了线段裁剪的速度.     

The Research of Anti-Wear Properties of Organomolybdenum Compounds in the Engine Oils

A four-ball tester was used to evaluate the anti-wear performance of three kinds of organomolybdemun compounds in the engine oils, i. e., molybdenum dialkyldithiophosphate (MoDDP), molybdenum dialkyldithiocarbamate ( MoDTC), and sulphur and phosphorus freeorganomolybdeum (Molybdate). The results indicate that a low concentration of MoDDP doesn' t improve the anti-wear properties of the commercial engine oils, but a high concentration of MoDDP can obviously improve the anti-wear properties and the load-carrying capacity of the engine oils. MoDTC doesn' t improve the antiwear properties of the engine oils, but worsens the anti-wear properties of the oils. Signifi can timprove ment of frictional and wear characteristics is obtained with Molybdate added in the commercial engine oils and the formulated oils.     

Certification Institutions Expected to Update and Transfer Information on Present Standards

Standards are the basis for production enterprises to organize production, ex-factory inspection, trade (delivery) and technical exchanges, product certification, quality arbitration and supervision.……     

Certification Becomes Important for the I Quality; and Safety Supervision of the Chinese Liquor Sector

The end of 2007, over 200 unit products of more than 80 Chinese firms have passed the quality grade certification for liquor products. These products involve distilled spirits, beer, wine, yellow wine, fruit syrup wine and others, and cover over 80% of the national top-branded liquor products.……     

Deposition and Coating Properties on CVD Tungsten

Surface characterization and microstructure studies are performed on chemical vapor deposited (CVD) tungsten coating. There is about 2 μm thickness diffusion layer of tungsten in the molybdenum substrate. The thermal shock test shows tungsten coating has good adhesion with molybdenum substrate, but the elements of oxygen and carbon in the tungsten coating have the bad affection to the adhesion. The result of high-temperature diffusion experiment is the diffusion rate from molybdenum substrate to tungsten coating is faster.     

Analysis of marine hydrobiont lipid extracts as possible cryoprotective agents

We studied a combined effect of the cryoprotectants both of lipid and carbohydrate origin at the presence of DMSO or without it on cell viability and the RNA synthesis in the embryonic mollusc and echinoderm cell cultures obtained at different developmental stages. Cryoprotective properties of exogenous lipids correlated with their thermotropic behavior. Lipid extracts from marine hydrobiontes, which thermal transitions are characterized by relatively small part of calorimetric thermogram area lying at temperatures above 0 °C (6–18%), were found to possess a considerable cryoprotective activity. The results are discussed in relation to the prediction of the cryoprotective activity of lipid extracts for marine animal cells. In addition, it was found that marine invertebrate cells can be cryopreserved without DMSO at the presence of trehalose and lipid extracts of some marine hydrobiontes.     

Low-Temperature Properties of Silver

Pure silver is used extensively in the preparation of high-temperature superconductor wires, tapes, films, and other configurations in which the silver not only shields the superconducting material from the surrounding materials, but also provides a degree of flexibility and strain relief, as well as stabilization and low-resistance electrical contact. Silver is relatively expensive, but at this stage of superconductor development, its unique combination of properties seems to offer the only reasonable means of achieving usable lengths of conductor. In this role, the low-temperature physical (electrical, thermal, magnetic, optical) and mechanical properties of the silver all become important. Here we present a collection of properties data extracted from the cryogenic literature and, to the extent possible, selected for reliability.     

Early ironwork in Biscay: Survey,excavation, experimentation and materials characterization. An integral study of the mountainside ironworks (ferrerías de monte or “haizeolak”)

ABSTRACT

The production of iron in Biscay (Basque Country, Spain) has been a hallmark of this territory of the North of the Iberian Peninsula throughout its history. The Archaeology team of the Basque Country Mining Museum has spent 13 years, so far, studying the origins of this activity through the evidences left at the old pre-hydraulic iron production workshops known as mountainside ironworks (ferrerías de monte) or haizeolak. It has catalogued 170 archaeometallurgical sites of this type in Biscay, and the archeological excavation of some of them has led to the knowledge of the different stages of the production process that took place in these workshops. The team has also experimentally reproduced the work carried out in a mountainside ironworks from the High Middle Ages, and it has currently started the characterization process of this type of activity through the study of the collected materials.     

Optimum-Simulation von Ernteprozessen

Zusammenfassung Bei der Gestaltung von Ernteprozessen — beispielsweise des Prozesses Mähdrusch, Körnertransport und -abnahme — als transportverbundene Fließarbeitsverfahren mit mindestens zwei verschiedenen Arbeitsmitteln gibt es einen großen Optimierungsspielraum. Solche Prozesse sind mehrstufige Bedienungsprozesse mit gemischter Anordnung der Bedienungseinrichtungen. Außerdem besitzen sie stark ausgeprägte räumliche Aspekte. Es wird vor allem gezeigt, welche Merkmale solcher Prozesse in Simulationsmodellen abgebildet sein müssen, welche Zielgrößen in Abhängigkeit von welchen Einflußgrößen unter Berücksichtigung welcher Prozeßbedingungen ermittelt werden sollten und wie der Bewertungsprozeß zur Ermittlung der gewünschten Informationen gestaltet werden muß.     

Mechanism Study on the Wear of CrAlTiN Coated High-Speed Steel Twist Drills Under Dry Cutting Conditions

As demands about environment protection are growing up, dry cutting technology is getting more and more concerns from all over the world. Main works performed here are study on dry cutting performances and wear mechanisms of M2high-speed steel (HSS) twist drills with CrAlTiN multicomponent coatings, which was deposited using magnetron sputter ion plating system, in drilling 45 and 30CrMnSiA steel, and their comparisons to those in drilling the same steel but using monolayer CrN and commercial TiN coated drills. Drilling performances of drills are evaluated mainly through the measurements of width on outer corner flank land and the cutting forces. Results show that performances of CrAlTiN coated drills are better than those of monolayer CrN and TiN coated drills. In drilling 45 and 30CrMnSiA steel, the average tool life of the CrAlTiN coated drills are 17.2 and 11.8 times higher than those of the uncoated drills. Observing wear of the drill with scanning electronic microscope, results show that there is no crack or spallation of the CrAlTiN coatings in wear zones. Main mechanism of the wear here is adhesion.     

Structural Characteristics of TiO2 Ceramic Coating by Micro-Plasma Oxidation

TiO2 ceramic coatings with thickness of 20 μm were formed on the surface of pure titanium by micro-plasma oxidation. Their micro-structures were investigated by by using X-ray diffraction and their surface images were detected by using scan electronic microscope. There were three kinds of TiO2 coatings, pure anatase type TiO2 phase, mixed phases consisted of rutile type TiO2 phase and anatase type TiO2 phase, pure rutile type TiO2 phase. The coating surface with the pure anatase type TiO2 phase is rough, while the coating surface with the pure rutile type TiO2phase is smooth. The upper coating surface with the mixed type TiO2 phases is anatase type TiO2 structure and the subsurface of the TiO2 coating is rutile type TiO2structure.