Study on stress and deformation of keyhole gas tungsten arc-welded joints

Keyhole gas tungsten arc welding(K-TIG)of Q345 low alloy steel plates was simulated by using SYSWELD software.The temperature field of the K-TIG welding process was simulated with three different combined heat sources and was compared with the weld profile that was obtained experimentally.The temperature field that was obtained by a combination of a double ellipsoid heat source on the upper half and a three-dimensional Gauss heat source on the lower half was similar to the real situation.The effects of plate thickness,gap and welding speed on the deformation and stress of the K-TIG welded joints were investigated by K-TIG welding numerical simulation.A reduction in the thickness of the weld plates reduced the z-direction deformation and transverse residual stress;an appropriate gap reduced the residual stress and an increase in the welding speed reduced deformation after welding,but did not help to control the residual stress after welding.     

自动喷水灭火系统喷头类型、特点及应用

简要介绍自动喷水灭火系统喷头的分类、特点及应用。     

异程式供暖系统最大不平衡率的应用

利用分户供暖下供下回异程式系统允许最大不平衡率，确定单元立管平均比摩阻的选取范围、单元入口压力预留值、建筑物入口的压力预留值。     

一种用于骨折术后辅助康复训练监控系统的设计

针对骨折术后的病人在做康复训练时,医生无法监控病人训练等情况,介绍了一种用于骨折术后辅助康复训练监控系统。该系统以stm32单片机为核心,采用MPU6050传感器采集病人手臂屈伸的次数,通过ESP8266 wifi模块将数据传送到云服务器,通过HC06蓝牙模块发送到病人的手机app.医生可以通过手机app访问云服务器,查看病人训练情况和设置病人训练计划。作为骨折术后或久卧的病人(防止肌肉萎缩)康复训练的辅助产品,有一定的应用前景。     

南海鸢乌贼营养成分分析与评价

采用现代生化分析法对南海鸢乌贼(Ryukyu squid)的营养成分进行分析与评价。结果表明:鸢乌贼胴体中水分、粗脂肪、粗蛋白和灰分分别为80.50%、0.49%、17.24%、1.37%。头足中水分、脂肪、蛋白和灰分分别为80.73%、0.87%、16.68%、2.88%,是一种高蛋白低脂肪水产品。鸢乌贼中氨基酸含量丰富,占鲜样总量的14.05%(胴体)、15.10%(头足),其中必需氨基酸(EAA)占氨基酸总量的40.89%(胴体)、40.11%(头足),鲜味氨基酸占45.89%(胴体)、46.51%(头足),必需氨基酸指数为79.56(胴体)、75.46(头足),其必需氨基酸的构成比例符合FAO/WHO标准。南海鸢乌贼中不饱和脂肪酸含量较高,占脂肪酸总量的49.90%(胴体)、54.55%(头足),其中EPA与DHA质量分数分别为6.9%(胴体)、5.67%(头足)和15.26%(胴体)、22.08%(头足),以上结果表明南海鸢乌贼有较高的营养价值和保健作用,具有较好的开发前景。     

芹菜叶中黄酮类化合物的提取与测定

文章以芹菜为研究对象,就其中总黄酮的提取分离和测定工艺进行了探讨。实验考察了单因素（提取溶剂浓度、物料比、回流提取时间和pH等）对总黄酮提取效果的影响,并在此基础上确定正交试验,得到了芹菜中总黄酮提取的最佳工艺条件∶40%（v/v）乙醇溶液,物料比（g/mL）1∶20,回流提取时间60 min,pH为6。得到总黄酮的含量为0.0794%。通过精密度实验和稳定性实验对测定方法进行评价。     

Numerical study of fillet weld leg height of sleeve repair welding for in-service pipeline

This paper presents a mechanical calculation and numerical simulation of the fillet weld of sleeve repair.The mechanical analysis based on the yield criteria is performed to obtain the minimum value of the fillet weld leg height to ensure the strength and loadbearing capacity of the weld. Within the framework of numerical simulation,the parameters of double ellipsoid heat source are determined by fitting method and the simulated molten pool morphology agrees well with the practical weld. Finite element models with various weld leg height are performed to predict the distribution and magnitude of the deformation and stress. The simulation takes into account thermal,metallurgical and mechanical factors,and the maximum value of the fillet weld leg height is obtained based on the magnitude of the deformation and stress.The mechanical calculation and numerical simulation results show that 1.2-2 times wall thickness is an optimal range of fillet weld leg height. And reasonable parameters of sleeve repair for in-service welding are provided for engineering field,which can improve the service life of the weld and production efficiency.     

天然气蒸汽转化制氢装置转化工序火灾爆炸原因分析

一、转化工序工艺概述 经过原料气压缩机增压的工艺天然气经过预热、脱硫，与经过过热中压蒸汽按H2O：C=3．5～4．0：1混合，进入对流段混合气预热器加热，经过上集气总管、猪尾管分别进入60根装有镍触媒的转化管中，天然气与水蒸气自上而下经镍触媒床层进行转化反应，最后经下集气管、下集气总管出转化炉。     

溶胶—凝胶法制备无机／有机杂化材料研究进展

本文介绍了溶胶－凝胶法的基本过程，对无机／有机杂化材料进行了分类，描述了溶胶－凝胶法制备无机有机杂化材料的常用方法，对杂化材料进行了评述，并预测了将来的发展趋势。     

火炬自动点火控制系统实现瓦斯回收利用

介绍火炬自动点火控制系统的构成和工作过程;详述控制部分、信号采集部分、信号输出与执行部分的工作原理,实现火炬自动点火的过程.