铝合金CO2激光深熔焊接过程中等离子体的热力学行为研究

结合光学多通道分析仪和高速摄像仪的观测结果,对6061铝合金CO2激光深熔焊接过程中等离子体的热力学行为进行了研究。分析了稳定的激光焊接过程初始阶段和焊接过程中及焊接过程不稳定时的等离子体热力学行为。实验结果表明,激光深熔焊接在初始阶段,等离子体的电子温度和离子温度偏离较大,并逐渐趋于平衡,温度梯度也逐渐变小;在稳定的焊接过程中激光功率的增加对等离子体的温度影响较小,等离子体尺寸变化对焊缝截面有重要的影响;等离子体温度急剧增加时,小孔内气压的剧增会引起等离子体上下起伏,使焊接过程中断或产生气体,而等离子体尺寸大小的波动则会影响焊缝成形。     

浅谈数字印花技术的进展

文章对数字印花技术的应用特点及其在设备、新型墨水研发等方面的最新进展进行了简要介绍。     

城市环境下车载Ad Hoc网络路由协议研究

考虑到城市环境中障碍物对网络性能的重要影响,在NS2(Network Simulator version 2)中加入了代表障碍物的概率穿透模型,使仿真环境更接近真实环境。针对AODV(Ad hoc On-Demand Distance Vector Routing)协议应用在城市场景下的缺陷,提出了一种改进的AODV协议——GE-AODV(Geocast Enhanced AODV)协议,该协议是基于位置信息的协议,并采用了多播方式来转发控制信息。仿真表明,GE-AODV降低了网络时延和控制开销,提高了网络可靠性。     

遗传算法在低空突防中的应用

针对在飞机低空突防航路规划中存在的计算复杂和收敛性等问题,论述了遗传算法基本原理,分析航路优化的性能指标。将遗传算法应用到航路规划中,航路进行染色体编码,根据随机数产生初始种群,适应度函数的大小进行选择、交叉和变异操作,达到算法终止条件后输出最优航路。仿真结果表明,应用改进的遗传算法规划的最优航线可以有效回避威胁和地形。     

煤粉深位火灾灭火剂及其水平蔓延规律

为解决一般灭火剂和灭火方式无法扑灭煤粉深位火 灾的问题,在水中加入表面活性剂,降低表面张力,提高其润湿煤 粉的能力,作为扑灭煤粉内部深位火灾的有效灭火剂。通过设置 实验装置筛选出适用于煤粉深位火灾的灭火剂。通过实验得到灭 火剂的主要配方为 0.20%吐温-80、0.10%乙二胺四乙酸四钠、 0.05%丁二酸二异辛酯磺酸钠和 0.10%碳酸钾溶液,余量为水。 在渗透压力分别为 0.1、0.2、0.3 MPa 情况下,得到灭火剂渗透到 0.25、0.50、0.75 m 处的渗透时间,利用实验结果拟合得到了灭火 剂水平渗透蔓延煤粉的计算公式。     

A step forward towards a comprehensive framework for assessing liquefaction land damage vulnerability: Exploration from historical data

The unprecedented liquefaction-related land damage during earthquakes has highlighted the need to develop a model that better interprets the liquefaction land damage vulnerability (LLDV) when determining whether liquefaction is likely to cause damage at the ground’s surface. This paper presents the development of a novel comprehensive framework based on select case history records of cone penetration tests using a Bayesian belief network (BBN) methodology to assess seismic soil liquefaction and liquefaction land damage potentials in one model. The BBN-based LLDV model is developed by integrating multi-related factors of seismic soil liquefaction and its induced hazards using a machine learning (ML) algorithm-K2 and domain knowledge (DK) data fusion methodology. Compared with the C4.5 decision tree-J48 model, naive Bayesian (NB) classifier, and BBN-K2 ML prediction methods in terms of overall accuracy and the Cohen’s kappa coefficient, the proposed BBN K2 and DK model has a better performance and provides a substitutive novel LLDV framework for characterizing the vulnerability of land to liquefaction-induced damage. The proposed model not only predicts quantitatively the seismic soil liquefaction potential and its ground damage potential probability but can also identify the main reasons and fault-finding state combinations, and the results are likely to assist in decisions on seismic risk mitigation measures for sustainable development. The proposed model is simple to perform in practice and provides a step toward a more sophisticated liquefaction risk assessment modeling. This study also interprets the BBN model sensitivity analysis and most probable explanation of seismic soil liquefied sites based on an engineering point of view.     

水性油墨新闻纸洗涤脱墨工艺探讨

本文对水性油墨废纸洗涤脱墨工艺的影响因素进行了研究。结果表明，水性油墨废纸洗涤脱墨的最优条件为：浆浓8％，碎浆温度50℃，碎浆时间10min，pH=7，脱墨剂脂肪醇聚氧乙烯（7）醚（AEO-7）用量0．6％。在此条件下，洗涤法脱墨可以提高脱墨浆白度6．5％ISO，使残余油墨量下降了950．2mg/kg。AEO-7的洗涤脱墨效果优于六偏磷酸钠和十二烷基磺酸钠。     

分散黄6GSL晶型与其分散体热稳定性的关系

针对分散染料喷墨印花直喷墨水存在高温条件下稳定性不好的问题,研究了提纯溶剂与分散黄6GSL晶体结构的关系,探讨了研磨工艺对分散体粒径大小及研磨效率的影响,考察了分散黄6GSL晶体结构与其分散体在高温条件下的稳定性和过滤性能之间的关系。结果表明:采用60 ℃热水对分散黄6GSL提纯,其纯度可达99.46%;分散黄6GSL与自制分散剂4600W质量比为1∶1.5的分散染料,在分散研磨机转速为2 500 r/min条件下初研磨5 h,再在砂磨机转速为4 000 r/min条件下研磨14 h,制备的分散体平均粒径为90.39 nm;分散体在60 ℃条件下放置72 h前后,在绝对孔径为1 μm的聚偏氟乙烯滤膜中的过滤流量分别为428和333 g/min,具有良好的过滤性能和热稳定性,可用于制备高热稳定性分散染料直喷墨水。