Sparking at cathode tools during electrochemical machining in flow-through cells

The current density used in electrochemical machining can be increased only up to a certain value, above which the formation of electric sparks on the cathode (tool) is observed, whereby the latter is damaged and the anode surface becomes rough. The present work is devoted to the measurement of this critical density for small metal cathodes placed on the wall of a flow-through channel for Reynolds numbers from 1265 up to 5902 and static pressures ranging from 0.1 up to 1.0 MPa. The results are correlated by criterion equations which gave values of critical (sparking) cathodic current density,j _s, with an average error of 7.1 % for laminar flow and 4.1 % for turbulent flow. The equations can be used for the calculation of the sparking current density for industrial flow-through cells for electrochemical machining.     

Optical and thermal properties of poly(ethylene oxide) doped with MnCl2 salt

The optical and thermal properties of prepared poly(ethylene oxide)/MnCl₂ films were studied as a function of MnCl₂ concentration at room temperature. The observed optical energy gap (E_opt) and energy gap tail (ΔE) were determined from the measured absorption spectra. It was found that the optical energy gap decreases with MnCl₂ concentration, and the absorption coefficient reduces sharply at concentration of 5 wt% MnCl₂ compared with the neat PEO. Differential scanning calorimetry (DSC) measurement shows that the heat of fusion increases with the MnCl₂ concentration, while the melting point decreases. Correlation between the observed optical energy gap and heat of fusion is presented.     

The influence of preparation conditions on the electrochemical behaviour of CuO in a Li/CuO cell

A dozen CuO samples prepared under various conditions and from different starting materials were evaluated as cathode materials for a primary Li/CuO cell. The “thin electrode” method was used for rapid evaluation of the samples. Both coulombic efficiency and discharge voltage depend considerably on the method of synthesis. No correlation was found between the specific surface area and the resistivity of the samples on the one hand and the cathode performance on the other. Best results were obtained from CuO prepared by the oxidation of Cu₂O under controlled temperature and time of oxidation.     

Process integration in CASE environments

Research in CASE environments has focused on two kinds of integration: tool and object. A higher level of integration, process integration, which represents development activities explicitly in a software process model to guide and coordinate development and to integrate tools and objects, is proposed. Process integration uses software process models (SPMs) a process driver, a tool set, and interfaces for both developers and managers to form the backbone of a process-driven CASE environment. The developer's interface, a working environment that lets developers enact an SPM, and the manager's interface which gives managers and analysts the tools to define, monitor, and control the SPMs that developers are working on concurrently are discussed. The Softman environment experiment, an implementation of process-driven CASE environments with existing CASE environments, is reviewed     

草酸二异辛酯的合成

以酸化膨润土(SO42-/Bentonite)固体酸为催化剂、草酸和异辛醇为原料合成草酸二异辛酯。考察了焙烧温度对催化剂活性的影响。结果表明,焙烧温度为500℃时催化剂活性最好。考察了反应温度、原料配比、催化剂用量和反应时间等因素对酯化反应的影响,确定了最佳酯化反应工艺条件,即n(异辛醇)∶n(草酸)为3.5∶1、w(SO42-/Bentonite)为2.0%、反应温度140℃、反应时间3 h;在该条件下草酸的转化率达到96.4%。催化剂重复使用6次后,草酸的转化率仍可达到94.4%。     

A real-time road pricing system: The case of a two-link parallel network

A real-time road pricing system in the case of a two-link parallel network is proposed in this paper. The system that is based on a combination of Dynamic Programming and Neural Networks makes “on-line” decisions about road toll values. In the first phase of the proposed model, the best road toll sequences during certain time period are calculated off-line for many different patterns of vehicle arrivals. These toll sequences are computed using Dynamic Programming approach. In the second phase, learning from vehicle arrival patterns and the corresponding optimal toll sequences, neural network is trained. The results obtained during on-line tests are close to the best solution obtained off-line assuming that the arrival pattern is known.     

混合结构楼房爆破拆除倒塌范围的确定

通过对混合结构楼房爆破倾倒过程特点的分析,提出了楼房在倾倒过程中的运动计算模型,并应用体积平衡原理,得到这类楼房爆破爆堆参数计算公式,用该公式计算的结果与实例中爆堆实测数据相比较,相对误差不超过11%.     

单站被动定位及光电实现

目的　光电技术实现的单站被动定位具有重要的军事价值 ,本文介绍了其原理、方法和发展 .方法　本文中 ,单站被动定位分为激光和红外两部分内容讨论 .结果　明确了采用激光和红外技术的单站被动定位工作原理和存在的技术难点 ,同时 ,指出了被动定位的研究动向 .结论　文章表明单站被动定位及光电实现值得进一步研究 .