美国再生铝行业现状

美国再生铝市场的现状是,比最坏的时期更好一些,比最好的时期要差一些。再生铝行业一方面受到一些终端市场部分复苏的鼓舞,另一方面由于担心经济可能二次探底而畏缩不前。     

严格执行点检定修制 促使设备管理上台阶

叙述了长钢连轧厂推行点检定修的一些做法和取得的一些效益,并就预防设备故障的有关方面提出在生产应用上的一些问题和措施。     

汽缸体产生的一些缺陷及修理

本文简析参照一些文献介绍汽缸体的一些问题、缺陷以及修复工艺。因此,要求汽缸体必须具有一定的耐磨性。其工作条件高温高压、且活塞在其中往复运动,摩擦很大,处于这样一个复杂的环境中可以确定经常发生一些问题。     

门式刚架轻钢结构的设计与施工

介绍了门式刚架的一些特点,对设计、施工中应注意的一些问题作了探讨。     

在调控中加强风险管理

我们的主旨应该是:宁可把风险估量得大一些,多一些,防止盲目乐观,这对企业经济运行安全有利。     

楚歌掠过电解槽——铝产能过剩中的百态众生

亲,您有这种感觉吗?高兴时,年轻人都会聚在一起,喝点小酒,再去K歌,几首跑调的歌吼下来,满头大汗,压力很快得到释放。然而今天,我却想带着大家去听一组悲情的歌。听完之后,身处行业内外的亲们,或许会对产能过剩阴云笼罩下的电解铝企业多一些理解,多一些同情,多一些宽容,多一些思考。不多说了,说多了都是泪。Music,come on!     

高碳铬轴承钢标准探讨

根据生产实践 ,对高碳铬轴承钢标准进行分析和探讨 ,提出新标准中一些问题的同时 ,还提出一些建议。     

浅谈企业中机械设备的管理应用

针对目前的一些大型矿山企业,特别是西部地区一些老的国企在机械设备管理应用中所存在的一些问题,总结出加强企业机械设备管理应用应采取的措施,确保设备的投入率和利用率成正比,使机械设备管理为企业的长远发展发挥应有作用。     

金属中气体分析进展

根据９０年代前期的一些文献,对测定金属中气体元素氢,氧、氮及碳,硫元素分析的有关方法做了综述。重点是关于有色金属、重金属、稀有金属中气体元素分析法。同时,介绍了一些有关冶金气体分析的现代仪器,并对助熔剂的选择等问题作了一些叙述．     

谈保证淬透性结构钢标准

根据生产实践,对保证淬透性结构钢标准进行了分析和探讨,提出新标准中一些问题的同时,还提出一些建议内容。     

冶金EPC项目三维工厂设计软件应用分析

对国内外五种主流三维工厂设计系统软件的功能和适用性进行对比,归纳了三维工厂设计系统的创新性和优势。结合钢铁冶金EPC项目的全流程管理,阐明了三维工厂设计系统对国内冶金类工程公司的发展起到重要作用,并客观分析了钢铁冶金工程引入和使用三维工厂设计系统时应该注意的问题。     

先进高强度汽车用钢的多维度协同设计与调控

阐述了先进高强度汽车用钢的概念,介绍了其发展及应用情况。提出了汽车用钢多维度设计理念,包括热处理过程中的多尺度设计和具有良好成形性的汽车用钢设计。指出汽车轻量化设计不应仅局限于获得理想的力学性能,要进行多维度的协同设计,并通过智能化微观组织调控来定制及满足差异化的要求。     

对邢钢北京世贸商城工程冷轧带肋钢筋焊接网设计分析

对邢钢北京世贸商城工程的冷轧带肋钢筋焊接网设计进行了分析,认为该工程各部分的底网设计、纵向面网设计和横向面网设计合理,针对该工程编写的施工方案,在实际施工中取得了良好的效果。     

Retrospective analysis of the Beijing family of Mycobacterium tuberculosis in preserved lung tissues

Direct repeat spoligotyping of 85 paraffin-embedded lung biopsies was used to investigated the occurrence around Beijing of the Beijing family of Mycobacterium tuberculosis. Samples ranged in time from 1956 to 1990. Hybridization patterns were found with 49 (58%) samples, and 45 (92%) produced typical Beijing family patterns extending over the 34-year period.     

含铜镍尾矿重金属溶出特性试验研究

本研究以位于我国东北典型铜镍矿区为研究对象,对其进行尾矿重金属溶出特性分析,通过静态浸出实验研究尾矿粒径和固液比对尾矿中镍(Ni)释放浓度及溶液pH的影响;并研究模拟酸雨条件下尾矿中Ni和铜(Cu)的溶解释放规律;此外,也分析了微生物对尾矿中重金属的溶出特性的影响.结果表明:在初始pH=7. 0的浸出液中,尾矿中的Ni在第1天就释放得较为完全,其质量浓度达到0. 85～1. 73 mg/L。减小尾矿粒径会增加Ni释放量,固液比过高会减小Ni的浸出;模拟酸雨(pH=4. 0和6. 0)条件下,淋溶液pH值相对较稳定,说明尾矿的缓冲能力较强,低pH条件利于Ni和Cu的溶出.静态浸出和动态淋溶实验初期,Ni的质量浓度基本高于《污水综合排放标准》(GB8978-1996)中的Ni排放限值(1. 0 mg/L),说明铜镍尾矿具有污染水环境的风险.微生物溶出试验结果表明:35 d后Ni和Cu浸出率达到了38. 4%和32. 7%,较酸浸条件下分别提高了74. 5%和28. 7%,说明微生物作用会加剧重金属Ni和Cu的释放,从而增加其环境风险.     

生活垃圾热解发电的投资分析

以200t/d垃圾热解发电项目为例,分析了1~20年内的经济指标,计算了动态投资回收期及投资收益率,为以后类似项目的启动提供了一定的依据。     

大气水汽同位素组成的短期变异特征

Stable isotopes of atmospheric water vapor reveal rich information on water movement and phase changes in the atmosphere. Here we presented two nearly continuous time-series of δD and δ18O of atmospheric water vapor(δv)measured at hourly intervals in surface air in Beijing and above a winter wheat canopy in Shijiazhuang using in-situ meas-urement technique. During the precipitation events, the δv values in both Beijing and Shiji-azhuang were in the state of equilibrium with precipitation water, revealing the influence of precipitation processes. However, the δv departures from the equilibrium state were positively correlated with local relative humidity. Note that the δv tended to enrich in Beijing, but deplete in Shijiazhuang during the precipitation events, which mainly resulted from the influence of transpiration processes that enriched the δv in Shijiazhuang. On seasonal time-scale, the δv values were log-linear functions of water vapor mixing ratios in both Beijing and Shijiazhuang.The water vapor mixing ratio was an excellent predictor of the δv by the Rayleigh distillation mechanisms, indicating that air mass advection could also play an important role in deter-mining the δv. On a diurnal time-scale, the δv reached the minimum in the early afternoon hours in Beijing which was closely related to the atmospheric processes of boundary layer entrainment. During the peak of growing season of winter wheat, however, the δv reached the minimum in the early morning, and increased gradually through the daytime, and reached the maximum in the late afternoon, which was responsible by the interaction between boundary layer entrainment and the local atmospheric processes, such as transpiration and dew for-mation. This study has the implications for the important role of vegetation in determining the surface δv and highlights the need to conduct δv measurement on short-term(e.g. diurnal)time scales.     

Potential Obstacles to Successful Implementation of Public-Private Partnerships in Beijing and the Hong Kong Special Administrative Region

Public-private partnership (PPP) has been practiced for quite some time around the world and there are numerous infrastructure, construction, and building projects which are employing the concepts. Unfortunately, not all of these PPP projects are equally successful and some of these projects have been exposed to formidable obstacles. The need to identify potential obstacles for PPP projects is therefore becoming an important issue for both research and practice. Despite the amount of interest vested in PPP, it is normally the advantages of PPP that are touched on rather than the potential obstacles. Both Beijing and the Hong Kong Special Administrative Region (referred to as Hong Kong from here onwards) have been keen to introduce more PPP projects. This paper presents part of the findings of an empirical questionnaire survey in relation to the prevailing barriers to PPP success conducted in these two administrative systems. It was anticipated that the obstacles would be similar for these jurisdictions. Respondents were asked to rate the level of severity of thirteen potential obstacles toward PPP projects identified from a literature review. The top three obstacles rated by the Beijing respondents were found to be “lengthy delays in negotiation,” “lack of experience and appropriate skills,” and “lengthy delays because of political debate.” Similarly the first and third obstacles ranked by the Beijing respondents were also ranked within top three by the Hong Kong respondents, together with “very few schemes have actually reached the contract stage (aborted before contract).” It was also discerned that “less employment positions,” “reduce the project accountability,” and “high project costs” were all ranked bottom by both of the Beijing and Hong Kong respondents. Moreover, the results obtained in the United Kingdom reported in other studies also shown consistency with those of Beijing and Hong Kong. Therefore the research hypothesis was proved to be true. Although the importance of the obstacles was similar it was realized that the scores obtained in the United Kingdom survey were much lower. This observation showed that the British respondents were less threatened by the obstacles, probably due to the fact that they are much more experienced and confident in undertaking PPP projects compared to Beijing and Hong Kong. Further analysis of the data reflected that the responses within each administrative system were consistent as revealed from the Kendall’s concordance analysis. Although the Spearman rank correlation test indicated that there was no significant disagreement on the rankings of obstacles between respondents of the two administrative systems, considerable difference was detected by the independent two-sample t-test in the mean value of their responses between the two administrative systems for the two obstacles lack of experience and appropriate skills and lengthy delays in negotiation. In Beijing, respondents felt that lack of experience and appropriate skills were highly important ranking it second place, but in Hong Kong this obstacle was ranked eighth, showing their confidence in experience and skills. For lengthy delays in negotiation, although the ranking between Beijing and Hong Kong was similar the difference in score showed a large variation. This represents a difference in tendering procedures between the two administrative regions. Triangulation with real cases largely supports the survey findings.     

Calculating activities from the phase diagram involving an

A new method for calculating activities of components from phase diagrams involving several intermediate compounds has been presented, in which only the entropies of formation of the intermediate compounds are required. It is expected that this method will be useful in situations where the free energy of formation, partial molar enthalpy and other thermodynamic data are not available. The application of this procedure to the Au-Bi and Mg-Si systems demonstrates that this method is feasible. Finally, activity values for the Au-Sb system are calculated by this method. Former Student in the Department of Physical Chemistry, Beijing University of Iron and Steel Technology, Beijing, People's Republic of China     

Second primary cancers after cancers of the colon and rectum in New South Wales, Australia, 1972-1991

In this article, we present a survey on dental care and oral implantology in Beijing, China. The Chinese population comprises 1.2 billion or about 20% of the world's population. This survey shows: (i) there is a well-developed dental system in China, mostly operated by the Chinese government; (ii) in Beijing, there are 1328 dentists and oral surgeons and 515 special dental nurses working in dental departments of hospitals; (iii) about 2 million new patients visit the dentist every year; (iv) oral implantology is a new technology for the Chinese dentist and oral surgeon, as shown by the finding that in 1992, only 384 persons were treated with oral implants in a few hospitals in Beijing; however, most hospitals are interested in performing oral implantology in the near future; (v) imported implants are too expensive for Chinese patients, and therefore good qualified domestic implants and cheaper imported implants have a great market potential.