基于部分频率复用的多小区协作方案及容量分析

针对无线蜂窝网中的小区间干扰问题,给出一种基于部分频率复用的多小区协作传输方案.该方案将小区用户划分为中心用户和边缘用户,中心用户采用频率复用因子为1的本地基站通信,边缘用户采用频率复用因子为3的多基站协作通信,并通过对多个小区的基站进行功率控制,达到抑制小区间干扰、提高系统容量的目的.数值分析表明,相对于传统多小区蜂窝系统(Traditional Multi-Cell System,TMCS)和广义分布式天线系统(Generalized Distributed Antenna System,GDAS),所提多小区协作蜂窝系统(Multi-Cell Cooperative System,MCCS)可以有效地克服小区间干扰,提高系统容量.     

酸气回注技术发展现状及其在中国的应用前景

零排放的酸气回注技术是一种替代硫磺回收工艺的经济可行的酸气处理方法,同时也是一个减少温室气体排放的环保方法。为此,总结了酸气回注技术的发展和应用现状,结合实例对酸气回注和硫磺回收进行了经济技术和环保对比分析,结果表明：酸气回注方案的硫处理费用为1 270美元/t;而硫磺回收的硫处理费用为1 400美元/t,若进一步考虑CO₂排放、硫磺销售等因素,其综合处理费用将超过1 779美元/t。同时,分析了酸气回注在中国的应用需求及条件,展望了该技术在中国的应用前景,指出在下述几种情况下,为了取得最好的经济和环保效益,酸气回注会是一个不错的选择：①老气田气质变化后,硫磺回收装置已不适应生产需要而需改造;②新开发气田太偏远或H₂S含量太低,硫磺回收不经济或工艺技术不好解决;③部分新开发气田的天然气组成不稳定,进行硫磺回收投资大、风险高;④部分碳酸盐岩开发油田伴生气含H₂S,但含量变化大,进行硫磺回收工艺选择难度大;⑤火驱开发油田和采用蒸汽辅助重力泄油开发的稠油油田,其伴生气中H₂S含量大,但气量小,回收不经济;⑥低渗透油田用CO₂提高采收率等。     

The prediction of crack growth rates from total endurances in high strain fatigue—thirty years on

McClintock 1 , 2 was one of the first to model continuous‐cycling fatigue crack growth by assuming a succession of miniature low‐cycle‐fatigue (LCF) specimens at the crack tip. Elements ahead of the crack amass damage until the arrival of the tip itself. Such models had been summarized by Majumdar and Morrow, 3 but the author was unaware of these papers at the time. The ideas were pursued further by Chakrabortty 4 whose paper, again unknown to the author, was published in the same issue (1979, Vol. 2) of FEMS. In the original paper 5 crack propagation is represented by successive regeneration at the crack tip, the process becoming progressively easier as the crack grows owing to an increase in strain concentration. These ‘initiation’ cycles were related to the ‘Coffin’ expression for crack initiation, thereby introducing two empirical constants k and α. The paper is of the class ‘ρ/N’ where ρ is the assumed size of a crack‐tip process zone and N is the cycles required to traverse that zone. Expressions had been previously derived linking LCF with linear‐elastic fracture‐mechanics (LEFM) crack growth, using the parameter ΔJ. 6 (It was later shown that this was identical to using an equivalent stress intensity parameter. 7 ) It has been shown that the approach does not apply for crack depths < 180 μm. 6 At elevated temperature the ΔJ approach was successful for describing crack growth in the range 0.2–1.2 mm for the cobalt‐based alloy MAR‐M509 at 600 °C. 8 Other studies have in fact shown 9 that crack growth rates are approximately constant below a depth of 200 μm. Even to this day short crack growth relations in LCF and their practical use are not as familiar as those in LEFM. It may justifiably be argued that for every paper published on LCF short crack growth, several hundred have appeared dealing with LEFM crack growth in terms of the ‘Paris’ law. One of the original referees' comments was that the paper 5 should have been presented in terms of LEFM. The author nevertheless defended his approach because for small cracks it was thought useful to retain the crack depth explicitly. It will be shown that LCF crack growth data have a definite part to play in the assessment of components and structures.     

中薄板坯连铸结晶器浸入式水口的优化设计

应用数值模拟软件对唐钢中薄板坯连铸结晶器及浸入式水口内的钢水流场、温度场进行数值模拟,分析了水口结构、拉速、浸入深度和铸坯断面对流场和温度场的影响,在此基础上确定了水口的最佳结构和浸入深度,并在生产中进行了验证,不但提高了铸坯质量和产量且稳定了连铸生产。     

中国制造业企业缺什么？（上）

中国制造业企业缺什么?文章论述了缺合理的公司治理结构,缺健全的财务制度。国家最缺的是企业管理。提出了中国科技型企业面临的几个问题,指出了我国制造业与国外的主要差距。     

关于架空网络中几种供电模式的探讨

本文探讨了几种经典的 10kV网络供电模式 ,并对其工作原理、动态时序、使用环境、优缺点等逐一做了分析 ;提出了一种新型的环网供电模式 ,并对其做了较详细的分析     

E化供应链管理

介绍了电子商务环境下新的供应链管理模式-e化供应链管理,总结了e化供应链的特征,分析了构建e化供应链的可能性和必要性,并结合国情对在实施e化供应链过程中所应注意的问题进行了研究。     

仲裁裁决撤销程序中的重新仲裁问题探讨

本文针对重新仲裁与撤销裁决的关系,重新仲裁的条件及重新仲裁的主体和范围等总是进行了分析和探讨,并且提出了自己的看法和观点。