Effect of Product Conductivity on Field-Activated Combustion Synthesis

Experimental and modeling results on the field-activated combustion synthesis (FACS) of Nb₅Si₃ are reported. In the absence of an electric field and without reactant preheating, Nb₅Si₃ cannot be prepared by self-propagating high-temperature synthesis (SHS). Under the influence of a field a self-sustaining combustion wave is established whose rate of propagation decreases with traveled distance. For relatively low field values, the wave propagation mode changes from a continuous (smooth) to a spin mode. The product of synthesis depends on the mode of propagation. Synthesis during continuous wave propagation results in the formation of Nb₅Si₃, primarily in the α-modification. In contrast, when the wave propagates in a spin mode, the product is NbSi₂ with unreacted niobium. The present observations demonstrate a case where the field effect is not localized, as was the case in previous studies. The difference in behavior is attributed to differences in the electrical conductivities of the product phases.     

新型层状表面相锆基固体酸催化酯化反应研究

将所研制的层状表面相锆基固体酸催化剂用于一元、二元醇醋酸酯和其他羧酸酯类产品的合成 ,考察了其催化性能。研究发现 :层状表面相锆基固体酸催化剂对所考察的酯化反应具有很好的普遍适用性 ,但其酯化率与醇的性质和结构密切有关。催化反应动力学研究表明乙酸与丁醇、戊醇、己醇的酯化反应均为二级反应 ,且反应活化能均较低 ,分别为 47 4kJ/mol、2 3 3kJ/mol和 19 8kJ/mo     

Cu2O/Cu Cermet as a Candidate Inert Anode for Al Production

Cu₂O/ x Cu ( x =0–25 wt%) cermets were evaluated as a novel partially inert anode for aluminum (Al) production. The physical and mechanical properties, including the compressive strength, flexural strength, thermal expansion coefficient, thermal conductivity, and dc electrical conductivity were tested at room temperature and at temperatures up to 950°C. The coefficient of thermal expansion, compressive strength, flexural strength, thermal conductivity, and electrical conductivity of Cu₂O/Cu cermets increased with increasing Cu content. High-temperature electrical conductivity measurements showed that with increasing temperature, the electrical conductivity increased when the Cu content was below the percolation threshold, while it decreased when the Cu content was above the percolation threshold. A relatively stable CuAlO₂ layer formed on the cermet surface during electrochemical testing, and the corrosion rate of this anode was estimated to be about 1.8–1.9 cm/year in Al production.     

Point-based online value iteration algorithm in large POMDP

Partially observable Markov decision process (POMDP) is an ideal framework for sequential decision-making under uncertainty in stochastic domains. However, it is notoriously computationally intractable to solving POMDP in real-time system. In order to address this problem, this paper proposes a point-based online value iteration (PBOVI) algorithm which involves performing value backup at specific reachable belief points, rather than over the entire belief simplex, to speed up computation processes, exploits branch-and-bound pruning approach to prune the AND/OR tree of belief states online, and proposes a novel idea to reuse the belief states that have been searched to avoid repeated computation. The experiment and simulation results show that the proposed algorithm can simultaneously satisfy the requirement of low errors and high timeliness in real-time system.     

Possible use of methylbenzenes as electrolyte additives for improving the overcharge tolerances of Li-ion batteries

Based on the voltammetric behaviour of a series of methyl-substituted benzenes in 1M LiPF₆/EC-DMC electrolyte, xylene was selected and tested as an electrolyte additive for overcharge protection of Li-ion batteries. From the overcharge curves, CV behaviour and SEM observations of the cells in the presence of xylene, it was found that the additive can polymerize at the overcharged voltage to form a dense layer of isolating polymer film at the cathode surface, which blocks off further oxidation of the electroactive material and electrolyte and, therefore, improves the overcharge tolerance of the Li-ion battery. In addition, the xylene additive has shown only a slight influence on the cycling behaviour.     

无水焦粉粉尘治理工艺改造及综合利用

简述了无水焦粉生产过程中的粉尘污染及其危害，分析了目前粉尘污染的现状、研究情况、环境监测及改造的必要性，提出了解决无水焦粉粉尘治理工艺改造的方案及粉尘的综合利用。     

认识隐患预防事故

事故隐患是客观存在的，不论你是否承认，是否意识到，它都存在于企业的生产全过程，而且对员工的人身安全，国家的财产安全和企业的生存、发展都直接构成威胁。正确认识隐患的特征，对熟悉和掌握隐患产生的原因，及时研究并落实防范对策是十分重要的。下面就这方面的问题，谈一点粗浅认识。     

熔融石英陶瓷的性能及其应用

介绍了石英陶瓷的性能特点、制备过程及应用领域     

浅谈创业教育

按照《面向21世纪教育振兴行动计划》提出的目标，我国高等教育到2010年入学率接近15％，这个目标有可能提前实现；若按每年新出生人口为2000万计算，高等学校在校生规模将达到1500万，每年毕业生将在500万以上。面对这样沉重的就业压力，转变大学生毕业就是到社会上寻求工作岗位的就业观念，树立和加强创业教育，引导毕业生走自己的路，就显得有十分重要的特殊意义了。     

露天开采下盘无台阶采矿法

新桥硫矿首次在国内推行露天开采下盘无台阶采矿新工艺,该工艺具有剥岩少、基建快、出矿早、采矿工程延深快等特点。由于该工艺具有独特的靠帮方式和端部过渡方式,需严格控制底盘因爆破而导致的岩体滑动。该工艺的实施已取得了显著的经济效益。