鞍钢ASP中薄板坯连铸机生产刃具钢的质量控制

通过对鞍钢ASP中薄板坯连铸机生产高碳刃具钢的炼钢、精炼、连铸各工序进行优化控制,有效保证了铸坯表面质量和内部质量的稳定,满足用户的需求。     

A note on the analysis of metal threads

Abstract

The present work demonstrates by means of two practical examples the extreme importance of examination of cross sections of metal threads to obtain an overview of their structure and of the different materials employed in their manufacture. Problems that might be caused by disturbance of surface features during polishing were prevented by covering the sample before embedding with a layer of nickel, using electroless deposition. Results from scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy (SEM-EDX) showed that, although the mean chemical composition of both metal wires is the same, their metallurgical structure is completely different: one consisting of pure silver with inclusions of copper particles and the other a silver–copper alloy.     

A bronze statue of a Meroitic archer-king: New data

Abstract

The bronze archer-king statue, masterpiece of the Sudan National Museum in Khartoum, was discovered in 1974 on the site of Tabo, Argo Island, in North Sudan. Its aesthetical and technological qualities inspired archaeologists to perform a complete study and full conservation in Zurich in the 1970s. The multidisciplinary work included iconographic and scientific investigations as well as defining a conservation protocol, and the results were published in 1986. On the occasion of an exhibition in Paris entitled Méroé: Un empire sur le Nil in 2010, a complementary study was conducted in the Centre de recherche et de restauration des musées de France (C2RMF) while restoration treatment was carried out. With a 40-year gap between the first work and the present effort, this example demonstrates, on one hand, the evolution of technological analysis methods and progress in the study of metallurgy and materials. On the other, it shows how the restart of necessary conservation interventions could be based on detailed knowledge of the first protocol and treatment.     

A linear optimization approach to the combined production planning model

Two fundamental processes usually arise in the production planning of many industries. The first one consists of deciding how many final products of each type have to be produced in each period of a planning horizon, the well-known lot sizing problem. The other process consists of cutting raw materials in stock in order to produce smaller parts used in the assembly of final products, the well-studied cutting stock problem. In this paper the decision variables of these two problems are dependent of each other in order to obtain a global optimum solution. Setups that are typically present in lot sizing problems are relaxed together with integer frequencies of cutting patterns in the cutting problem. Therefore, a large scale linear optimizations problem arises, which is exactly solved by a column generated technique. It is worth noting that this new combined problem still takes the trade-off between storage costs (for final products and the parts) and trim losses (in the cutting process). We present some sets of computational tests, analyzed over three different scenarios. These results show that, by combining the problems and using an exact method, it is possible to obtain significant gains when compared to the usual industrial practice, which solve them in sequence.     

三叶青藤特性及苗木繁育技术研究

在3、5、7、9、11月五个月份采集三叶青藤二年生茎藤,分别用北京产双吉尔GGK6号生根粉50mg．kg-1浸泡2小时进行扦插试验;用随采随播、5天后播种、10天后播种、15天后播种、20天后播种五种方法进行种子发芽试验。结果表明,扦插育苗试验时五个月份的生根率分别是79．2％、82．8％、69．6％、62．4％、44％;种子育苗时五种处理的发芽率分别是96％、79％、57％、20％、11％。5月份扦插育苗效果最好,生根率达到82．8％;播种育苗时随采随播的效果最好,发芽率达到96％;在生产上采用扦插育苗会有更多的优势。     

金属切削机床润滑油的使用期限

对润滑油在金属切削机床的使用期限进行检测对比发现,润滑油的质量按油中金属杂质的含量确定,机床各机构的技术状况根据机构的实际状况以及油中金属杂质含量的变化作出评价。润滑油中金属杂质的含量对不同型号的机床是不一样的,它取决于注入润滑油系统的油量V和变速箱齿轮的总齿数Z。对于被测定的各种型号的机床,Z/V的比值是一定的。试验结果表明,对被试验的各型普通机床,与现行标准比较,润滑油的使用期限可增加一倍。     

不同浓度的氯化胆碱在不同时间内对某些植物生根的效应

本文通过一系列实验，找出了适宜于紫露草大量繁殖的最佳氯化胆碱浓度以及处理的最佳时间。     

纤维素降解过程中金属离子作用的研究

用微量量热法研究了7种金属离子及几种混合离子对纤维素酶降解纤维素反应的影响.实验结果表明,在pH=4.60,T=310K时,相同浓度的离子中Li+、Na+、K+、Ni2+、Zn2+、Co2+离子均表现出抑制作用,其中Li+抑制作用显著;Cu2+有明显的激活作用.当Li+、Na+、K+3种离子混合共同作用于反应时,表现出激活作用;当Ni2+、Cu2+、Zn2+3种离子,Co2+、Ni2+2种离子混合共同作用于反应时,表现出抑制作用.     

Analysis of tensioned membrane structures considering cable sliding

INTRODUCTIONTensionedmembranestructuresaremostsuitableforuseasroofstructureforavarietyofbuildingtypes,astheyprovidealight,elegant,andefficientstructurespanningoveralargeclearspace (Otto,1 973 ) .Examplesincludegymnasi ums,exhibitioncenters ,concertpavilio…