Numerical investigation for turbulent heat transfer of TiO2–SiO2 nanofluids with wire coil inserts

A numerical model has been developed for turbulent flow of hybrid nanofluids in a tube with wire coil inserts. The model was developed from van Driest eddy diffusivity equation. The model can be implemented with the consideration of new variables in eddy diffusivity of momentum and heat by using the coefficient, K and Prandtl index, ζ, respectively. The numerical analysis are undertaken for wide range of Reynolds number, different volume concentration, ? and various pitch ratio, P/D of wire coil. The numerical results were validated with the experimental data of TiO₂–SiO₂ nanofluids undertaken for wide range of Reynolds number and volume concentration. The final regression models of coefficient K and Prandtl index ζ were developed as a function of Reynolds number, Re or dimensionless radius, R⁺, volume concentration, ? and pitch ratio, P/D. A good agreement between the experimental data and numerical model indicating the validity of the numerical model for hybrid nanofluids with wire coil inserts. The numerical analysis was proved that the hybrid nanofluids contributes to higher Nusselt number and thus have better heat transfer performance compared to single nanofluids.     

Experimental investigation on controlled cooling by coupling of thermoelectric and an air impinging jet for CPU

In this study, experimental tests have been carried out on the coupling thermoelectric cooling module with minichannel heatsink subjected to impinging airflow for cooling desktop central processing unit (CPU). A controlled thermoelectric-forced test system was designed for this purpose. This was designed using electronic Arduino card. The proposed hybrid cooling system was compared with the conventional forced air-cooling technique. Three power of heat source (CPU) were adopted, investigated, and compared, namely 60, 87, and 95 W. Performance of controlled thermoelectric cooling with three preset temperature were experimentally examined. The effects of air velocity and thermoelectric input current on the case temperature (T_case), thermal resistance, and heat transfer coefficient were analyzed. Results showed that the T_case increases with the increase of its input power. In addition, increasing air jet velocity and thermoelectric input current improve CPU cooling significantly. For a CPU power of 95 W, the recorded T_case temperature was 57°C with the conventional system. While it was maintained below 50°C in the hybrid system. The thermoelectric cooler has had a major effect on CPU cooling, having 15% improvement over conventional forced air-cooling. However, this was accompanied by an increase in energy consumption in the range of 45 W.     

新疆葡萄树伤流液中矿质元素含量的主成分及聚类分析

研究了不同地区、不同品种新疆葡萄树伤流液中矿质元素的含量、特征元素和分布特征。采用电感耦合等离子体发射光谱法测定不同产地、不同品种的新疆葡萄树伤流液中各矿质元素的含量,并采用SPSS 17.0主成分分析法和聚类分析法对测定结果进行特征分析。结果显示:经主成分分析得3个主成分,其累计方差贡献率达92.490%。第一主因子的方差贡献率为60.923%,故确定其所对应的Ca、Mg、P和S是新疆葡萄树伤流液中所含的特征元素。聚类分析将6个样品,基本按品种和地域性聚为2组。说明不同产地、不同品种的葡萄树伤流液中矿质元素呈现一定的选择性累积和地域差异。     

心草水提液和醇提液抑菌作用初步研究

实验用水和70%乙醇从心草中提取其活性成分,探讨了其抑菌作用。结果表明,心草提取物对微生物有明显抑制作用,水提物的MIC值分别为大肠杆菌为5%,金黄色葡萄球菌、枯草杆菌为3%、苏云金杆菌、短小芽孢杆菌为1%。醇提物的MIC值分别为大肠杆菌为3%,金黄色葡萄球菌、枯草杆菌、短小芽孢杆菌为0.5%,苏云金杆菌为0.25%。     

聚类+连体段判别的维吾尔文档图像单词切分

目前针对印刷体维吾尔文档图像的切分研究主要集中在字母切分上，单词切分的文献较少，且存在着标点符号难处理，未合并被拆分书写的单词等问题，同时单词切分准确率有待进一步提高。在对文档图像进行投影处理的基础上，通过[K]均值聚类算法[（K]-means）对文本行中所有连体段之间的间隙进行聚类分析得出最佳的间隙判别阈值，然后对所有连体段进行筛选和粗略识别，并结合对间隙的阈值判别结果来确定单词的精确切分点和获取被拆分书写单词的位置信息。在选取的100张文档图像中测试时，结果表明该方法能有效去除标点符号对切分结果的影响，准确合并被拆分书写的单词，并且平均单词切分准确率保持在99%以上。     

基于J2EE的多文种考籍变更系统相关算法的设计与实现

针对新疆维吾尔自治区高中学业水平考试信息管理系统的使用需求,并对相应的多文种报表生成等特殊要求,本文首先设计基于J2EE框架(JSF+Spring+Hibernate)的考籍变更子系统结构及各模块功能,根据需求制定考籍变更原则和流程,实现相应的变更算法,并用iText技术,有效解决B/S系统中的准考证、转出(入)申请表等多文种报表的生成。实践结果表明,本文所提出的相关算法具有实时性和鲁棒性,具有很好的实用效果。     

印刷维吾尔文特征提取之方向码

特征提取方法的选择是影响识别率的一个至关重要的因素。而印刷识别中的分类特征很多,让每一类特征具有良好的分类能力和稳定性是仍需要解决的问题。现就以具有高稳定性和抗干扰能力的八方向码特征为例,对其提取方法进行了全面的阐述。     

A New Method for Flood Routing Utilizing Four-Parameter Nonlinear Muskingum and Shark Algorithm

Water Resources Management - Considering the great importance of flood prediction, flood routing based on Shark Algorithm (SA) and Four-Parameter Nonlinear Muskingum (FPNM) has been proposed in the...     

Embedding PbS quantum dots in MAPbCl0.5Br2.5 perovskite single crystal for near-infrared detection

Organometal lead-halide perovskites demonstrate excellent photovoltaic performance in the visible (Vis) region. However, their lack of response in the near-infrared (NIR) region limits their applications in broadband photodetectors. Here, PbS quantum dots (QDs) were successfully embedded in MAPbCl_0.5Br_2.5 single crystal by solution-processed epitaxial growth. Perovskites can effectively act as efficient charge transporters. The mobility of MAPbCl_0.5Br_2.5 with 1 wt% PbS quantum dots crystal is about 85 cm²/(V·S), which is similar to that of pure MAPbCl_0.5Br_2.5 single crystal. Meanwhile, the composite crystal exhibited a broadband response wavelength from the Vis (625 nm) to the NIR (850 nm) with fast response times (τ_on/τ_off = 6/9 ms and τ_on/τ_off = 19/43 ms in the Vis and NIR regions, respectively). The photodetector demonstrates a responsivity of 0.02 mA/W with a specific detectivity of 1.2 × 10⁸ Jones under 5.1 mW/cm² 850-nm illumination at 10-V bias. These results suggest that we have obtained high-quality composite crystals with improved photo response in the Vis to NIR region.     

基于Windows Mobile的多语种电子辞典开发研究

Windows Mobile拥有微软的掌上版本操作系统,在与桌面PC和Office办公的兼容性方面具有先天的优势,用户越来越多。该文章将介绍基于Windows Mobile的多语种电子辞典的开发技术。始终考虑新疆维吾尔自治区的多民族特征,在双向汉维翻译,相关工具,界面的多语种化方面尽量给使用者提供方便的翻译功能。主要技术包括在Windows Mobile中维吾尔文的处理,界面的多语种化,UI元素,字体,图像对不同屏幕的自适应。