目前影像（胶片）保存中的问题和方法

近年来，由于卤化银感光材料形成的影像档案，在保存中出现了严重的褪色和变质，因此，影像保存中的稳定性，越来越引起人们的关心。50年代以前的影像档案中多数属于硝酸片。由于硝酸片易燃、化学性能不稳定，逐渐被醋酸片取代，因而形成了50～60年代两种胶片同时使用的时期。人们期望醋酸片能长久的保存下去。国外的一些研究资料表明，认为醋酸片可以保存数百年，     

Compressive Strength of Hydrostatic-Stress-Sensitive Materials at High Strain-Rates

Many engineering materials demonstrate dynamic enhancement of their compressive strength with the increase of strain-rate, which have been included in material models to improve the reliability of numerical simulations of the material and structural responses under impact and blast loads. The strain-rate effects on the dynamic compressive strength of a range of engineering materials which behave in hydrostatic-stress-sensitive manner were investigated. It is concluded that the dynamic enhancement of the compressive strength of a hydrostatic-stress-sensitive material may include inertia-induced lateral confinement effects, which, as a non-strain-rate factor, may greatly enhance the compressive strength of these materials. Some empirical formulae based on the dynamic stress-strain measurements over-predict the strain-rate effects on the compressive strength of these hydrostatic-stress-sensitive materials, and thus may over-estimate the structural resistance to impact and blast loads, leading to non-conservative design of protective structures.     

瓜丝熬

护眼小知识眼睛就像一台精细的相机,由各种零部件构成,而这些零部件需要用各种营养素为原料制作而成。如视网膜就好像是感光底片,需要维生素A作为底片上的感光材料。缺乏感光材料,照片曝不了光。青皮南瓜含有丰富的维生素A,让我们学做一道以南瓜为主料的美食。     

身边的环保

不浪费剩余的香皂香皂的制作原料有脂类、弱碱以及植物油等,有数据显示:一个制皂厂,使用比较先进的工艺,每年生产香皂约环保不仅是政治家、企业家的事,也事关每一个普通人。让我们从身边的细微小事做起吧!有时,需要的仅仅是改变一下你的习惯而已。