Short-term effects of drawing water for connectivity of rivers and lakes on zooplankton community structure

During 28-29,September 2005,water was drawn from Hanjiang River and Houguan Lake to the Yangzi River via Sanjiao Lake and Nantaizi Lake in Wuhan in order to provide favorable conditions for ecosystem restoration.To evaluate the feasibility and validity of drawing water as a means of ecosystem restoration,zooplankton populations were studied 3 times (before,immediately after finishing and a month after drawing water)at seven locations from 27 Sept.2005 to 2 Nov.2005.Water quality in the lakes was mostly improved and zooplankton species richness decreased as soon as drawing water had finished but increased a month after drawing water.Zooplankton density and biomass was reduced in the lakes by drawing water but was increased at the entrance to Sanjiao Lake because of landform geometry change.Before drawing water,most species in Sanjiao lake e.g.,Brachionus sp.and Keratella sp.were tolerant of contamination.After drawing water oligotrophic-prone species such as Lecane ludwigii and Gastropus stylifer emerged.We conclude that drawing water could be important for improving water quality and favour ecosystem restoration.Dilution of nutrient concentrations may be an important role in the effect.     

The portrayal of disaster in Western fine art

This paper surveys the depiction of disaster in Western art over the centuries. Emphasis is placed on the Italian tradition, as Italy is a country that has a rich experience of both artistic developments and disasters and has provided inspiration to artists from other countries. The survey begins with Classical art and continues with the Mediaeval fresco tradition. The vision of disaster was expanded when naturalism was introduced into art during the Renaissance. Whereas earthquakes had been a prime motivation for artistic representations in the Mediaeval period, during the Baroque volcanic eruptions seem to have been more popular, especially given the remarkable artistic output around Mount Vesuvius in the 18th century. Marine painters concentrated on storm and shipwreck, but often with delineations of extreme atmospheric phenomena. In the 19th century John Martin and others painted the Apocalypse. In the 20th century, Expressionism favoured lively depictions of natural hazards and so, surprisingly, did certain forms of metaphysical abstraction. Disaster has been seen in Western fine art in six ways: as spectacle, as allegory (through Classical mythology or Biblical drama), as a votive instrument of atonement, as a visual commemoration of an extreme event, and as a dramatization of a metaphysical proposition.     

盒形件拉深模CAD系统研究

此文介绍了作者自行开发的盒形件拉深模CAD系统的组成、功能以及编程中的若干技术问题。该系统人机对话界面友好,整个设计过程程序化程度高。系统运行时只需输入工件特征数据就可根据人机对话和菜单选项完成整个设计过程,最后输出工件图、毛坯图、排样图、工序图、模具零件图及总装图。     

板材拉深成形性能智能化预测系统

对板料成形性能智能化技术的特点及其开发和应用的意义进行简要的介绍,并详细阐述了板料成形性能智能化系统的整体结构和功能,详细论述了该系统开发的关键技术部分:用户信息输入部分、推理和评定部分的设计思路和具体内容。     

一种基于ActiveX Automation技术的报表表示方法

分析了企业中产品设计完成后,应用ActiveXAutomation技术生成产品的各种物料清单报表,建立了报表检查机制,较好地解决了企业图档管理中的报表自动校正生成问题。运用该方法开发的报表管理器,已经在多家企业得到应用,取得了很好的效果。     

基于特征编码的拉深件CAPP信息模型

此文在分析拉深件零件特点的基础上,对其特征的信息构成进行了研究。采用成组技术,提出了一种特征编码的信息表达方式。该方式不仅可以方便地实现零件的自动工艺设计,而且还可实现零件的成组工艺、模具的成组设计,从而缩短产品的生产周期,降低成本。     

变断面细长产品成形方法探讨

通过对变断面细长件产品特点的分析和其加工成形方法的比较,确定无模拉伸是最佳的成形方法.无模拉伸是近年来新开发的一种成形工艺,文中作了系统分析和介绍.     

确定复杂形状旋转体拉延毛坯尺寸的计算机AutoCAD方法

提出了一种基于AutoCAD软件的确定复杂形状旋转体拉深毛坯直径的计算机方法,它操作严谨、结果准确,比原有的3种方法简捷、快速,具有良好的推广应用价值。     

盒形件多点常力压边拉深模设计

对盒形件拉深成形 ,提出了在周向多个位置施加压边力的方法 ,且根据常力压边原理 ,用弹簧和橡胶作弹性元件 ,可根据需要在不同位置施加不同的压边力 ,且每个位置的压边力在拉深过程中保持定值。以此设计的模具所提供的压边力 ,更适合复杂零件的成形 ,也更符合拉深工艺对压边力的要求     

摩擦对板料极限拉深系数的影响

通过对板料拉深法兰变形区和直壁传力区的应力分析 ,应用功平衡法 ,推导了极限拉深系数与摩擦系数之间的关系式 ,并讨论了摩擦对拉深性能的影响。