Influence of an external electric field on the microstructure of superplastically deformed 7475 Al

An externally applied electric field retarded strain-enhanced grain growth and promoted dynamic recrystallization during superplastic deformation of 7475 Al. Also, a more extensive dispersoid-free zone was observed in specimens deformed in the electric field, suggesting that the electric field increased the contribution of diffusion creep to superplastic deformation. The electric field promoted the coarsening of dispersoids, especially in the vicinity of the grain boundaries. Possible mechanisms for the observed effects are discussed.     

基于DTC的井下架线式电机车变频调速装置设计与应用

分析了井下架线式电机车运行现状及存在的维护量大、维护成本高、故障率高等问题.设计了一种基于DTC的电机车电机变频调速装置,现场应用情况表明其具有起动力矩大、维护量小、故障率低、节约成本的优点.指出了应用DTC变频调速技术改造传统的矿用架线式电机车直流传动系统的必要性及应用前景.     

辐射敏感综合症--AT病研究进展

共济失调性毛细血管扩张综合症(AT)是一种单基因突变引起的遗传性疾病，表现为高辐射敏感性、进行性神经退变、免疫缺陷、早衰及易患癌症等。本文综述了AT病的研究概况，包括AT临床症状、AT基因的定位、结构与功能、辐射对AT细胞信号传导的影响、AT基因组不稳定性及基因治疗。     

Reactor length-scale modeling of chemical vapor deposition of carbon nanotubes

Chemical Vapor Deposition (CVD) of carbon nanotubes from a gas mixture consisting of methane (carbon precursor) and hydrogen (a carrier gas) in the presence of cobalt, nickel or iron catalytic particles in a cylindrical reactor is modeled at the reactor length-scale by solving a continuum-based coupled boundary-layer laminar-flow hydrodynamics, heat-transfer, gas-phase chemistry and surface chemistry problem. The model allows determination of the gas-phase fields for temperature, velocity, and various species as well as the surface-species coverages and the carbon deposition rate. Various available experimental and theoretical assessments are used to construct the necessary database for gas-phase and surface chemistry and gas-phase transport parameters. A reasonably good agreement is found between the model predicted and the experimentally measured carbon nanotubes deposition rates over a relatively large range of processing conditions.     

基于遗传算法的工作辊温度场参数优化模型

针对热连轧机工作辊热辊形计算中温度场模型的热交换等参数难以确定的问题 ,建立了基于遗传算法的参数优化模型 ,可以解决复杂条件下的热参数的求解问题。利用优化参数计算的轧辊温度场与实际测量结果一致。     

Distributed Rule-Regulated Spectrum Sharing

Dynamic spectrum access is a promising technique to use spectrum efficiently. Without being restricted to any prefixed spectrum bands, nodes choose operating spectrum on-demand. Such flexibility, however, makes efficient and fair spectrum access in large-scale networks a great challenge. Prior work in this area focused on explicit coordination where nodes communicate with peers to modify local spectrum allocation, and may heavily stress the communication resource. In this paper, we introduce a distributed spectrum management architecture where nodes share spectrum resource fairly by making independent actions following spectrum rules. We present five spectrum rules to regulate node behavior and maximize system fairness and spectrum utilization, and analyze the associated complexity and overhead. We show analytically and experimentally that the proposed rule-based approach achieves similar performance with the explicit coordination approach, while significantly reducing communication cost.     

多序列迭加生成值的合理性判定——病态信息检测案例

论文针对目前普遍存在于各种管理性考评工作中的专家打分问题进行了研究,提出了一种特定条件下专家打分值的合理性判定模型。该方法已在某组织的实际考评工作中进行了实验与应用,取得了较好的效果,为控制专家打分随意性和病态信息的产生,提供了一种新的思路。     

Preparation of branched polyacrylonitrile through self‐condensing vinyl copolymerization

Branched polyacrylonitrile (PAN) was prepared through a self‐condensing vinyl copolymerization of acrylonitrile and 2‐(2‐bromopropionyloxy)ethyl acrylate (BPEA). The branched architecture of the product was confirmed by NMR spectra and the average degree of branching (DB ) was estimated. Through a comparison of the intrinsic viscosity of the product with that of its linear analogue, the contraction factor g′ was calculated. It was found that the viscosity of the branched PAN was obviously lower that that of linear PAN. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

全封闭Ar气保护电渣重熔GH4169合金

上海五钢采用ALD 5t全封闭Ar气保护电渣重熔炉 ESR(Ar)冶炼了GH4 16 9合金锭 ,分析结果表明 ,ESR(Ar)电渣锭氧、硫含量和锭头尾碳、铝、钛之差远低于一般ESR工艺 ;VIM(真空感应熔炼 ) +ESR(Ar)工艺冶炼合金中平均氧含量 6× 10 - 6 远低于VIM +VAR(真空电弧重熔 )工艺冶炼合金中平均氧含量 13× 10 - 6 ,所以ESR(Ar)工艺脱氧效果优于VAR工艺     

使用地热能的吸收式制冷系统

吸收式制冷系统可以利用低品位的热源来制冷，相对于常见的蒸汽压缩式制冷系统而言在这方面具有优势。我国是一个地热资源很丰富的国家，为了充分利用这一资源，我们有必要对以地热为热源的吸收式制冷系统进行研究。本文着重分析了使用地热资源的溴化锂吸收式制冷系统。