Loss characteristics and flow rectification property of diffuser valves for micropump applications

The primary motivation for this work is to provide data on the loss characteristics and flow rectification performance of flat-walled microdiffuser valves for Reynolds numbers between 100 and 2000 which is considered deficient in literature. The diffusers are designed with a fixed slenderness of 15 and an aspect ratio of 0.92 and with diverging angles ranging from 4° to 120°. The total pressure loss coefficient of the diffuser flow is determined experimentally. Components of the loss are studied in detail by numerical simulations. Results from the computations are in satisfactory agreement with the measurements. Simulations are also carried out for nozzle flows. Based on the experimental and the computational results, efficiencies of the diffuser valves are calculated. It is shown that, for laminar flows, global flow separation plays a significant role in reducing the loss of the diffuser. Consequently, the diffuser angle corresponding to the optimum diffuser efficiency varies from 40° at Re = 100 to 20° for Re ?500.     

Optical transmittance enhancement and bandgap widening of ZnO:Al powders by W codoping

(Al, W)-codoped ZnO powders with a constant molar ratio of Zn:Al (99:1) and various molar ratios of W:Al (0–0.02) were synthesized by a sol–gel process and characterized by X-ray diffraction, field emission scanning electron microscopy, and UV–vis and luminescent spectrophotometry. The experiments indicated that the powders illustrated increased c-orientation and a decreased average particle size with increasing W content. The W doping also resulted in the enhancement of transmittance in the UV–vis light range and the widening of the bandgap. Optimal efficiency appeared at molar ratio of W:Al = 0.01. Moreover, the W doping led to the formation of a new emission center and the enhancement of the emissions in range of visible light.     

可用性工程学在人机界面中的应用研究

可用性是人机交互系统设计中需要重点考虑的方面之一,它关系到人机交互能否达到用户的预期目标,以及实现这一目标的效率性和便捷性。可用性意味着使用产品的人能够快速而方便地完成任务,也意味着确定某件事物工作良好,一个有能力和经验平常的人能够使用该事物达到目的。可用性问题存在于人们所使用的任何产品、系统、服务或事物中,论文以人机界面着手,浅析可用性理论在人机界面设计中的应用。     

Controllable preparation of SnO2 nanoplates and nanoparticles via hydrothermal oxidation of SnS2 nanoplates

A facile hydrothermal oxidation route has been proposed for the controllable preparation of SnO₂ nanoplates and nanoparticles, using the home-made SnS₂ nanoplates as a precursor. It was found that the temperature played an important role in the microstructures of the obtained products. While nanoplates of tetragonal phase SnO₂ were synthesized via hydrothermal treatment of the SnS₂ nanoplates in 15 vol.% H₂O₂ aqueous solution at 180 °C for 24 h, only nanoparticles of tetragonal phase SnO₂ could be obtained via hydrothermal treatment of the SnS₂ nanoplates in 15 vol.% H₂O₂ aqueous solution at 200 °C for 24 h. The as-prepared products were characterized by means of X-ray diffraction, field emission scanning electron microscope, and Raman spectra, and their possible formation mechanisms were also discussed.     

An investigation on bonding mechanism and mechanical properties of Al/Ti compound materials prepared by insert moulding

Al/Ti metallic composites prepared by insert moulding are attracting more attention now because of their low production costs, low energy consumption, simple production procedure and high interface bonding strength. However, the insert moulding of pure Al and pure Ti has not been reported so far though it can be considered as a fundamental in studying Ti-alloy/Al-alloy interface bonding. Therefore, the insert moulding of pure Al and pure Ti is intended in this paper and the corresponding microstructure, elements distribution and mechanical properties of the interface are also analyzed. As a result, a good metallurgical bonding can be achieved at the interface of Al and Ti, which is mainly comprised of intermetallic compounds TiAl₂ and TiAl₃ formed in the transition zone around Ti insert and Al matrix, respectively, depending on different heat treatment parameters and cooling conditions. It is shown that the hardness of the interface layer varies with the types of interface sublayers. For the compact sublayer, the hardness is higher than those of both base metals (Al and Ti) with the maximum value reaching HV520. However, the hardness of the granular interface sublayer depends on the proportion of the intermetallic compounds and aluminum matrix. The average shear strength of the interface layer could reach about 60 MPa, which is higher than that of the aluminum matrix (43 MPa) tested in this experiment. The result also shows that shear crack initiates at bottom face of the specimen (adjacent to locator) in the aluminum matrix nearby the interface.     

长北气田钻井液回收重复利用实践与认识

针对长北气田钻井液配制成本高,完井后的废钻井液处理环境压力大等问题,开展了废钻井液的回收重复利用实践,并获得了良好效果.废钻井液含大量无机盐、有机盐和聚合物等处理剂,性能稳定,根据地层和潜在复杂情况,适时调整即可直接循环利用.通过废钻井液回收重复利用,不但充分利用了废钻井液的现有性能,降低了钻井液处理成本,缩短了配浆时间,还具有良好的经济效益和社会效益.     

Bi2SiO5 nanosheets prepared by molten salt method

Bi₂SiO₅ nanosheets were successfully synthesized by the molten salt method in NaCl–Na₂SO₄ flux using Bi₂O₃ and SiO₂ as raw materials. XRD analysis and SEM observation show that the incorporation of salt medium can greatly lower the formation temperature of Bi₂SiO₅ phase, and promote their crystallization. The results also demonstrate that the mass ratio of salts to reactants, the reaction time, and the calcination temperature have significant effects on the phase formation and morphology of the Bi₂SiO₅ powders. The UV–vis spectra result shows that the absorption of the Bi₂SiO₅ powders located at 380 nm, and the corresponding band gap energy (Eg) calculated is 3.26 eV.     

The master sintering curves for BaTi0.975Sn0.025O3/BaTi0.85Sn0.15O3 functionally graded materials

The most important aim in the design and processing of functionally graded materials (FGMs) is to produce devices free from any deformation. Smart choices of different combination of graded layers, as well as the heating rate during sintering, are important for the fabrication of high-quality FGMs. In this study, BaTi_0.975Sn_0.025O₃/BaTi_0.85Sn_0.15O₃ (noted as BTS2.5 and BTS15, respectively) FGM was used as a model system for the construction of master sintering curves (MSCs) and estimation of the effective activation energies of sintering for different BTS graded layers. The MSCs were constructed, for BTS2.5 and BTS15 graded layers in FGMs, using shrinkage data obtained by a heating microscope during sintering at four constant heating rates, 2, 5, 10 and 20 °/min. The effective activation energies were determined using the concept of MSC; values of 359.5 and 340.5 kJ/mol were obtained for graded layers BTS2.5 and BTS15, respectively. A small difference of the effective activation energies of chosen powders made it possible for us to prepare high-quality FGMs, without delamination, distortion or other forms of defects.     

杨山高压渗流井设计与施工及其取水效果分析

结合陕北地区干旱缺水、河流泥沙含量较高的特点,利用河床松散砂砾石含水层为天然滤床开发地表水,研究了地下取水的新工艺。以长庆油田杨山油库高压渗流井施工为例,对高压渗流井的取水原理、工艺设计思路、施工方法及技术要点进行了总结及效果分析。所得结果可供相关研究人员参考。     

基于OpenCV的立体匹配算法的研究与实现

提出了一种基于OpenCV的立体匹配算法,先使用投影仪在物体表面添加棋盘格角点特征,再利用OpenCV库函数对角点特征的像素精度和亚像素精度位置进行检测和计算.最后使用基于OpenCV的立体匹配算法完成图像对间角点特征的匹配.为了验证该算法,在VS2008环境下利用VC++进行了实验.算法验证实验和三维测距实验的结果表明,该算法匹配效果理想,匹配精度也高于传统的视差图匹配算法.