石英尾砂料仓及其气力助流系统的设计

以江苏某企业的石英尾砂为研究对象,基于Jenike剪切理论,分析石英尾砂的物料性质、四棱锥料仓结构对重力流卸料的影响,考虑料仓卸料口尺寸和斜锥角对料仓内物料流动状态的影响,设计石英尾砂料仓及其辅助气力助流系统,且将其应用于江苏某企业试运行。结果表明:石英尾砂的含水率在14%(质量分数)时,物料的内摩擦角最大,物料粒径越细小,物料内摩擦角越大,但达150μm时增势趋于平缓;设计的石英尾砂料仓及其辅助气力助流系统可保障物料装卸料性能和防止物料堵仓;年产2万t石英尾砂的条件下,设计的石英尾砂料仓及其辅助气力助流系统可为企业节省200万元的生产成本,且社会环境效益显著。     

除尘器新型褶式滤筒的结构优化及系列化设计

以新型褶式滤筒为研究对象,选取滤筒褶数N_2、褶夹角θ、褶高h、过滤风速v为影响因子,除尘器压力损失为响应值,基于响应曲面法分析影响因子对压力损失的影响,建立滤筒除尘器压力损失的预测模型并得到滤筒褶皱结构最优参数。以滤筒内径D、筒体高度D_1为标准尺寸,依据相关国家标准设计滤筒筒体部分;以锥体高度D_2、锥体上圆直径D_3为系列尺寸,利用尺寸变化法设计锥体部分;通过Access软件建立滤筒产品数据库。结果表明:当θ=5.2°,N_2=50,v=0.01 m/s,h=0.035 m时,除尘器压力损失最低;当D_1=1 000 mm,D=320 mm时,D_2和D_3最佳值分别为600,130 mm,故采用D_2/D_1=0.6,D_3/D=0.4的比值设计相应滤筒锥体系列。     

A dense and compact laser cladding layer with solid metallurgical bonding significantly improved corrosion resistance of Mg alloy for engineering applications

Although Mg alloy attracts great attention for engineering applications because of high specific strength and low density, low corrosion resistance limits its extensive use. In this study, Mg–Al–Zn–Mn alloy was treated via a laser cladding process to generate a dense and compact laser cladding layer with solid metallurgical bonding on the substrate for improving corrosion resistance, effectively hindering the corrosion pervasion into Mg alloy. The corrosion current density declined from 103 μA/cm² for Mg alloy to 13 μA/cm² for the laser cladding layer in NaCl aqueous solution. Moreover, the laser cladding layer was slightly corroded in comparison with Mg alloy in NaCl aqueous solution. Besides, the microhardness of the cladding layer reached a mean value of 170.5 HV, 3.1 times of Mg alloy (56.8 HV) due to the in situ formation of hardening intermetallic phases. Wear resistance of laser cladding layer was also obviously improved. These results demonstrated that the laser cladding layer obviously enhanced anticorrosion property of Mg alloy for engineering applications.     

K4,4,p的点可区别的IE-全染色(p≥1008)

该文利用色集事先分配法、构造染色法、反证法探讨了完全三部图K_4,4,p (p≥1008)的点可区别IE-全染色问题，确定了K_4,4,p (p≥1008)的点可区别IE-全染色数。     

数据挖掘技术在软件系统中的应用

随着高新科学技术的发展,科学家研究出的利于人类工作生活的技术程序越来越多,大部分技术主要集中在如何帮助人们简化平时的工作量,能快速查找到自己所需要的信息,毕竟现代社会,工作效率和工作质量是关键。数据挖掘技术就具备这样的特点,数据挖掘技术在软件系统的应用将大大降低我们的工作量,提高我们的工作效率。现在我们研究数据挖掘技术在软件系统的应用,分析它是如何发挥其作用的,希望能提高使用该挖掘技术人员的使用效率。     

Zinc doped Fe2O3 for boosting Electrocatalytic Nitrogen Fixation to ammonia under mild conditions

Artificial nitrogen fixation is emerging as a promising approach for synthesis of ammonia at mild conditions. Inspired by biological nitrogen fixation based on bacteria containing iron, zinc doped Fe₂O₃ nanoparticles are proposed as an efficient and earth abundant electrocatalyst for converting N₂ to NH₃. In neutral media, it achieves a maximum Faradaic efficiency (FE) of 10.4% and a large NH₃ yield rate of 15.1 μg h^?1 mg^?1_cat. at ?0.5 V vs. reversible hydrogen electrode. This catalyst also exhibits excellent selectivity and stability. Theoretical calculations suggest the reaction follows the associative enzymatic mechanism and it has a barrier of as low as 0.68 eV.     

Model Selection for Unsupervised Learning of Visual Context

This study addresses the problem of choosing the most suitable probabilistic model selection criterion for unsupervised learning of visual context of a dynamic scene using mixture models. A rectified Bayesian Information Criterion (BICr) and a Completed Likelihood Akaike’s Information Criterion (CL-AIC) are formulated to estimate the optimal model order (complexity) for a given visual scene. Both criteria are designed to overcome poor model selection by existing popular criteria when the data sample size varies from small to large and the true mixture distribution kernel functions differ from the assumed ones. Extensive experiments on learning visual context for dynamic scene modelling are carried out to demonstrate the effectiveness of BICr and CL-AIC, compared to that of existing popular model selection criteria including BIC, AIC and Integrated Completed Likelihood (ICL). Our study suggests that for learning visual context using a mixture model, BICr is the most appropriate criterion given sparse data, while CL-AIC should be chosen given moderate or large data sample sizes.     

阿鸠田电站SF35-16/4100水轮发电机绝缘工艺

云南保山阿鸠田电站由三台SF35-16/4100水轮发电机组成,单机额定容量35 MW,额定电压10.5 kV,定、转子绕组均采用F级绝缘。根据用户要求采用了一些新绝缘结构,并进行了大量的工艺试验,生产中选择优质材料,严格控制工艺过程,使已出厂的三台发电机定、转子线圈及定、转子装配的电气绝缘性能优良。文章就机组定、转子绕组绝缘工艺进行了简要的介绍。     

差分跳频通信系统的特点及性能

文章介绍了一种新型的短波跳频通信技术——差分跳频,分析了差分跳频技术区别于常规跳频技术的主要特点。针对按序列检测的信号接收方法,对差分跳频通信系统在AWGN信道下的性能进行了理论分析,同时做出相应的计算机仿真,证实了差分跳频通信技术和按序列检测方法的结合,使通信系统在AWGN信道下的性能得到了比较显著的提升。