凭谁问 廉颇老矣 尚能饭否?——海雨天风中的古巴与传奇人物菲德尔·卡斯特罗

<正>中国人有个习惯,对年届八十八岁老者,称之"米寿"。对于过去岁月里的世界风云人物中仍然健在的菲德尔·卡斯特罗来说,他的生日礼物中有中国的寿星捧桃。今年七月,在他的生日即将到来之际,他在自己的家里迎来了中国客人:中华人民共和国主席习近平。这是习近平近三年来的第二次探访。就在准备这篇稿件的时候,正是"七二六运动"61周年之时。一年前的7月26日,古巴和八个加勒比国家的领导人参加了在古巴圣地亚哥蒙卡达兵营举行的盛大集会。1953年的这一天,27岁的菲德尔·卡斯特罗带     

Experimental studies of salts removal from metal surfaces by wind and rain

Abstract

This paper outlines an experimental programme aimed at determining the mechanisms of salt removal from metallic surfaces by wind and rain. The paper provides data and process understanding that will be integrated into a holistic model of atmospheric corrosion. Experiments are reported in which fine salt crystals were deposited either wet (as fine droplets of seawater) or dry onto a surface. The surfaces were then placed in a wind tunnel and salt loss was determined as a function of wind speed. In another experiment, the motion of simulated raindrops falling onto metal plates was determined. Finally, in a third series of experiments, video footage of simulated rain on metal surfaces was studied in order to determine both the subsequent motion of rain and its cleaning efficiency. The efficiency of surface cleaning by wind and rain, as determined by these experiments, was then related to Australian climatic conditions. A future paper will present mathematical models of the processes defined in this paper.     

循环经济理念下的再生资源产业

一、发展再生资源产业是建设循环经济的重要内容 循环经济是相对于传统的线性经济发展模式而言的.在传统的线性经济发展模式中,社会经济运行体系主要由生产系统和消费系统构成,自然资源通过生产系统转变为产品,产品又通过消费系统变成为废物,废物最终被抛弃进入环境中,造成对自然环境的污染和破坏.这种线性的经济运行模式导致的最终结果必然是自然资源的枯竭和自然环境的破坏,是一种不可持续的发展模式.     

加速度连续可变的加减速控制规律研究

加减速控制是数控系统插补器的重要组成部分,是数控系统开发的关键技术之一.数控加工的目标是实现高精度高效率的加工,因此,一方面要求数控机床反应快,各坐标运动部件能在极短的时间内达到给定的速度,并能在高速运行中快速准确地停止在预定位置,缩短准备时间;另一方面要求加工过程运动平稳,冲击小.文章介绍了一种加速度连续且可变的加减速控制规律.加速度连续可使速度平稳上升或降低,减少对机床的冲击,保证机床运动的平稳性;加速度可变可提高机床的进给速度.     

明知山有虎 偏向虎山行——高冷废金属市场中的金属回收机械设备制造产业

<正>2014年中国有色金属与钢铁市场都进入了最惨淡的时期,即便是2013年9月起取消了废钢进口自动许可管理,但废钢市场仍创6年来新低。多年艰辛与坚持,中国金属回收机械设备制造产业苦撑待变——明知山有虎,偏向虎山行在当前国际经济低迷、中国经济下行压力加大的背景下,国际与中国金属市场都也已然步入了产品供应与需求减速、上下游价格低水平波动、微利竞争加剧、弱势被迫退出的新常态,相关行业都步入了三十年来最艰难的境地。     

TC4在海水和酸雨中的腐蚀磨损交互作用研究

以GCr15/TC4为摩擦副,蒸馏水、人工海水和人工酸雨为腐蚀润滑介质,使用TRB3销-盘式摩擦磨损试验机研究不同水基介质对TC4合金磨蚀机制及腐蚀磨损交互作用的影响。结果表明：不同水基介质中TC4合金的磨损机制不同,海水中疲劳剥层最严重,蒸馏水中粘着磨损最明显,酸雨中磨粒磨损最显著,且海水和酸雨中的摩擦系数略低于蒸馏水。酸雨中磨痕的长度、宽度、深度均大于海水和蒸馏水;TC4合金磨损体积表现为酸雨>海水>蒸馏水,随循环次数增加呈线性增长。3种介质中TC4合金腐蚀磨损交互作用比率表现为酸雨>海水>蒸馏水趋势,蒸馏水中TC4材料流失由机械因素主导,海水和酸雨中则由腐蚀交互作用与机械因素主导;随着载荷增加蒸馏水中的腐蚀交互作用比率降低,机械因素对磨蚀的影响逐渐显著。     

一个中国人导演了令全球市场瞩目的“黑色星期三”

<正>1月18日,慵懒的周日午后,葛卫东出现在其麾下期货公司杭州营业部开业仪式上,笑容满面。几天前,市场就疯传葛卫东导演了1月14日伦敦铜市崩盘,当天伦铜最深跌至每吨5353.25美元,盘中跌幅一度超过8%,刷新了2009年7月以来的最大跌幅,上海铜期货午盘封死跌停。     

Corrosion behavior of copper,tin, and bronze CuSn14 in acid rain solution

The corrosion behavior of copper, tin, and bronze CuSn14 is studied in simulated acid rain (pH 4.5) by electrochemical techniques, cyclic voltammetry and electrochemical impedance spectroscopy. The potentiodynamic formation of anodic oxide film on copper and tin is described in terms of high-field model. Cyclic voltammetry shows that dissolution of bronze is higher than of pure copper metal in acid rain. Electrochemical impedance spectroscopy data reveal that oxide films formed on copper and tin have a higher resistance and suppressed diffusion process through the surface layer than the oxide film formed on bronze CuSn14 at the same conditions.     

The reaction of simulated rain with copper,copper patina,and some copper compounds

Rain samples of varying acidities related to the New York City metropolitan area environment for the epochs 1890, 1950, and 1980, as well as two additional variants, were used to study the accelerated reaction with copper, existing patina specimens, and 13 copper compounds (minerals). Cuprite (cuprous oxide) and brochantite (a basic cupric sulfate) formed rapidly under a wide range of conditions. Posnjakite (a hydrated basic cupric sulfate) forms under more limited conditions, sometimes simultaneously with brochantite, but subsequently converts to brochantite. Most copper compounds degrade under low pH (<2.5) conditions. The opposing roles of the reaction of copper and patina with precipitation to increase the pH and the evaporation of the precipitation to decrease the pH were also investigated. While there is considerable evidence that the chemistry of precipitation has changed markedly during the last century as a result of anthropogenic activity, the results show that it is unlikely the changes in the rain composition will have any significant effect on copper patinas. However, the more highly acid fogs do have the potential to produce substantial materials degradation.     

实施校企合作培养铸造人才满足社会需求

综述校企合作办学的途径，分析企业参与教学后，学校在人才培养方向，课程体系及教学方法上的改革。