Structural characteristics of titanium coating on copper substrates

The growth characteristics of titanium films deposited on glass, silicon (100) and oxygen free high purity copper substrate using magnetron sputtering have been investigated using X-ray diffraction, electron microscopy and scratch indentation techniques. The study of interface between the titanium film and the substrate was carried out to determine coating thickness, as well as intermixing of the elements at the interface. Studies revealed that the interface is free from voids and intermixing of the film and the substrate. Microstructural and diffraction analysis showed that the Ti coating was polycrystalline and exhibited columnar growth. The Ti crystallite size varied between 24 and 58 nm depending on the substrate. The thickness of the films were typically about 4 μm. Scratch test indicated that the films are adherent and the first critical load to failure was observed to be 4·5 N ± 2 N.     

Structural, dielectric and electrical properties of Li2Pb2La2W2Ti4Nb4O30 ceramic

Li₂Pb₂La₂W₂Ti₄Nb₄O₃₀ complex ferroelectric oxide was prepared by using a high-temperature solid-state reaction method (calcination temperature, ~1100 °C and sintering temperature, ~1150 °C). Room temperature preliminary structural analysis shows formation of a single-phase compound. The nature of microstructure (i.e. grain distribution, presence of voids, grain size, etc) recorded using scanning electron microscope (SEM) clearly suggests the formation of high quality and density of pellet samples. Studies of temperature dependence of dielectric constant, tangent loss and polarization show the existence of ferroelectric phase transition in the material at high temperature (307 °C). Detailed studies of temperature dependence of electrical parameters (i.e. impedance (400?475 °C), modulus, conductivity, etc) of the material clearly suggest a strong correlation between its microstructure (i.e. bulk, grain boundary, etc) and electrical properties. The nature of temperature variation of d.c. conductivity showed an Arrhenius behaviour of the material. A signature of ionic conductivity in the material was observed in its a.c. conductivity spectrum. The nature of frequency dependence of a.c. conductivity of the material can be explained by Jonscher’s universal power law. Electrical transport properties of the material show existence of non-exponential type of conductivity relaxation.     

混合策略的维吾尔语名词词干提取系统

通过对维吾尔语名词形态结构进行研究,构造了名词有限状态自动机（FSM）;针对自动机的缺陷使用最大熵模型给有限状态自动机加入了歧义词缀识别能力,根据维吾尔语的元音和谐特点,建立了基于规则和信道噪声模型的元音和谐处理方法。有机地结合以上三种方法构造出了基于规则和统计的名词词干提取方法。为了有效利用现有的资源,提高系统的性能,把基于词典的词干提取方法与规则和统计结合的名词词干提取方法相结合,从而开发出多种策略相结合的维吾尔语名词词干提取系统。该系统具有较强的鲁棒性,准确率保持95%以上。     

配内燃机车离心风机的设计改型

利用商业软件Fluent对配内燃机车离心风机内部气流的流动情况进行了数值模拟。模拟结果与实验结果对比表明,两者能够较好的吻合,误差在5％以下。在此基础上,对风机内部的流场分布,尤其是沿叶高方向气流的流动情况进行了分析,找到了导致风机效率较低的原因,并有针对性地对风机进行了改型。改型后的模拟结果显示,风机的效率提高了6％左右,效率提升较为明显。     

Studies on Mg/Fe hydrotalcite‐like – compound (HTlc): removal of Chromium (VI) from aqueous solution

The affinity of Mg/Fe hydrotalcite‐like‐compound (HTlc) for the removal of Cr (VI) from aqueous medium was studied as a function of pH, contact time, temperature, HTlc dose and Cr (VI) concentration. The fraction of Cr (VI) removal decreases with increase in pH of 3 to 10. The reaction kinetic study was undertaken by considering adsorption of Cr (VI) on the outer surface as well as diffusion within the pores of the adsorbent. The adsorption follows first order kinetics. The adsorption data fit well with the Langmuir isotherm model in the temperature range 30–50°C and the thermodynamic parameters viz. ΔG°, ΔH° and ΔS° were calculated to predict the nature of adsorption. The positive value of ΔH° indicates that the adsorption process is endothermic in nature.