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。     

双氧水冷漂助剂液中润湿剂的分离和鉴测

双氧水冷漂助剂液中的润滑剂——烷基硫酸钠可以在四级氧化铝柱上用氯仿和乙醇—水的淋洗体系进行分离而获得纯品;用NMR和GC法进行结构分析;两相滴定法测定其含量。     

Field emission mechanism from nanocrystalline cubic boron nitride films

An electron-emission theoretical model integrating the change in the grain size of nanocrystalline cubic boron nitride (c-BN) thin films was established. To understand better the essence of field emission, an accurate numerical scheme, the transfer matrix method, that can be used to compute the tunneling coefficients of the actual surface barrier, was also adopted. The present results show that the emission current from nanocrystalline grain films is far larger than that from regular grain films or bulk c-BN.     

消失模生产中应用表面光泽涂料防止球铁件产生夹渣缺陷

以汽车弹簧托架为实例，分析用EPC法生产球铁件时产生夹渣缺陷的原因，提出采用表面光泽涂料可有效防止夹渣缺陷的产生，同时亦可改善铸件表面粗糙度。     

Improving Thermal Stability of BaMgAl10O17:Eu Phosphor

Heterogeneous precipitation method was used to prepared surface coating on self-made BaMgAl10O17:Eu phosphor. Results illustrate that the coating film can be silicon dioxide in amorphous state with 50 nm in thickness. Photoluminescence results indicate that the coating layer presents an observable improved effect on the enhancement of thermal stability. When baked at 600 ℃ for 1 h, the luminance of coated BAM keeps at 92% higher than that of uncoated BAM by 23%. This protective effect can be attributed to the high compact degree and uniformity of this amorphous SiO2 coating film which is served as a diffusion block layer to inbreak oxygen atom, thus releases the oxidation extent of Eu2 effectively.     

La-OMS-2催化剂催化甲苯氧化制苯甲醛

合成了氧化锰八面体(OMS-2)分子筛,采用离子交换法和浸渍法制备了稀土金属La改性的OMS-2分子筛(La-OMS-2)催化剂,并用于甲苯液相选择性氧化制苯甲醛,考察了催化剂用量、反应温度、反应时间、氧气流量及溶剂种类对甲苯转化率和苯甲醛选择性的影响,对La-OMS-2催化剂进行了X射线衍射表征和BET比表面积测定。实验结果表明,离子交换法制备的La-OMS-2-A催化剂的活性高于浸渍法制备的La-OMS-2-B催化剂,在甲苯0.1mol、溶剂冰乙酸10mL、氧气流量60mL/min、La-OMS-2-A催化剂用量0.10g、反应温度353K、反应时间1.0h的条件下,甲苯转化率达61%,苯甲醛收率为56%。加入La对OMS-2分子筛中的MnO晶格结构产生了影响,提高了苯甲醛的收率。     

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。