Latent Image Reactions with Mercuric Chloride*

Destruction of surface latent image by mercuric-chloride solutions proceeds by a reduction of photographic speed obtaIned on subsequent development. in contrast to the loss of slope of the characteristic curve produced by most other surface latent-image bleaches. On gold-sensitized emulsions only port of the latent image could be bleached. and the proportion of resistant image increased with lengthening exposure lime. No such resistant lotent image could be detected with ferricyanide. cupric-bromide or acid dichromate bleoches, and these other solutions ottacked gold-silver alloys containing sufficient gold to protect them against corrosion by mercuric chloride. Other results suggested that gold enters the latent image from gold ions very firmly attached to the groins.     

A new understanding on the mechanism of fountain solution in the prevention of ink transfer to the non-image area in conventional offset lithography

In conventional offset lithographic printing, it has been well established that the existence of a continuous layer of fountain solution (FS) on the surface of the non-image area is an essential condition to ensure correct operation of lithography. However, the mechanistic function of FS in preventing the ink from being transferred onto the non-image area has not been fully understood. Several major mechanistic interpretations can be found in the literature, which are based either on comparing of static works of adhesion and cohesion of ink and FS, or on the splitting of the 'weaker' FS layer. Although the latter becomes more accepted, direct experimental evidence is difficult to find in the literature. On the other hand, confusing information found in the literature showed that the ink-transfer (or non-transfer) observations reported in many case studies correlate well with simple comparisons of works of adhesion, cohesion and spreading data of ink/FS, ink/plate and FS/plate obtained under the static condition. These results, therefore, imply that, in explaining the function of FS in preventing ink transfer to the non-image area, the ink/FS interfacial adhesion failure would be the dominant mechanism. The work presented in this study covered two specific areas in order to address and better understand the responses of ink and FS layers and their interface to forces encountered during ink transfer. Firstly, an analysis of lithographic plates contaminated with a cationic polymer revealed that the violation of the ink non-transfer condition of the plate non-image area due to contamination could be predicted by traditional criteria of plate wetting and works of adhesion and cohesion. However, these traditional criteria cannot reliably predict the non-transfer condition of the ink on the clean non-image area that was covered by FS. Secondly, in some novel experiments conducted in this study using ice or Teflon as a substrate, the works of adhesion and cohesion were not able to predict ink transfer in most cases. Direct experimental evidence from this work revealed that splitting of the FS layer was involved in the prevention of ink transfer to the non-image areas, and that the thickness of the FS layer was critical in allowing the splitting to occur.     

Thermomechanical processing of 42CrMoS4 steel

Abstract

Billets of 42CrMoS4 steel were subjected to a programme including forging and rolling to different reduction ratios, followed by quenching and tempering to simulate online thermomechanical treatment (TMT) during rolling. The mechanical properties obtained were compared with those obtained by conventional heat treatment (CHT) (quenching from 860°C and tempering). It was found that increasing the hot reduction ratio from 18 to 60%, accompanied by a decrease in the finish rolling temperature from 900 to 750°C, enhances strength only at the expense of elongation, while rapid quenching instead of air cooling from the same finish rolling temperature yields improvements in both strength and ductility. It was also found that CHT provides higher hardness, whereas TMT provides higher impact toughness. TMT will confer major economic savings since the heat treatment is achieved online.     

基于Excel 2003及VBA办公自动化的实现

Excel作为现今办公普及的Office套装软件之一,其内置的函数OFFSET、VLOOK-UP以及名称和标准宏语言VBA使其办公自动化水平得到了极大的扩充。通过对Excel中的函数OFFSET和名称的应用以及矩形框与单元格数据的关联可以实现批量准考证的制作,实现了办公自动化。该方法操作简单,自动化程度高,工作效率高。     

多边形OFFSET中无效环的去除算法

对于多边形OFFSET后产生的自交环现象,提出一种求解自交点的基于单调链的平面扫描算法,并对环的判别提出了一种简便而有效的方法。最后,对算法的时间复杂度进行了分析。实验表明,该算法高效而稳定地处理多边形OFFSET后产生的自交环。     

利用OFFSET函数将一列数据转为多列数据的原理与应用

在高校信息管理工作中,Excel电子表格是一个常用工具,它已经成为数据库数据和普通用户数据交互的重要平台.可以使用查询语句简单地从数据库中导出单列数据,但如何把从数据库中导出的一列数据转换为多列数据,是一个让人头疼的问题.虽然互联网上有提供“多排表工具”等宏命令方法,可以解决一股的多排表问题,但在不熟悉宏命令的情况下,这种方法的局限性是显而易见的.文章将详细分析利用OFFSET等相关函数解决将一列数据转换成多列数据的方法,并试图引导读者独立地解决类似的问题.     

OPTIMAL ALGORITHM FOR NO TOOl- RETRACTIONS CONTOUR-PARALLEL OFFSET TOOL-PATH LINKING

A contour-parallel offset (CPO) tool-path linking algorithm is derived without tool-retractions and with the largest practicability. The concept of “tool-path loop tree” (TPL-tree) providing the information on the parent/child relationships among the tool-path loops (TPLs) is presented. The direction,tool-path loop,leaf/branch,layer number,and the corresponding points of the TPL-tree are introduced. By defining TPL as a vector,and by traveling throughout the tree,a CPO tool-path without tool-retractions can be derived.