55Q轻轨断裂分析

55Q轻轨在使用前由于受到机械加工力而断裂，进行了化学成分，显微组织、夹杂物和低倍检验分析。结果表明，其发生断裂的主要原因是存在较多的小发纹（白点），加之较严重网状组织、夹杂物、晶粒粗大和边部脱碳组织，在机械加工力的共同作用下，导致轻轨发生断裂。     

Genetic algorithm for the optimization of rubber insulated high voltage power cables production lines

The optimization of vulcanized EPM/EPDM mechanical properties must be a fundamental task for electric cables producers. Insulator mechanical properties depend on the vulcanization degree of the rubber, which is obtained by manufacturers by means of a number of different peroxides acting as reticulation inducers. The industrial production process consists in the extrusion coating of the conductor with elastomeric compounds, and in the successive vulcanization of the insulator rubber through the continuous vulcanization tube, a pressurized high temperature tube filled with nitrogen (the high temperature is a condition necessary to activate the cross-linking agent). Finally, water and/or air are used to cool the insulated cable at ambient temperature. Changes of process variables associated with the vulcanization tube can cause considerable changes in output mechanical properties of the elastomers.In this framework, in the present paper a novel genetic algorithm with zooming and elitist strategy is used for the determination of optimal production line parameters to use in order to maximize rubber output mechanical properties. Nitrogen temperature and rubber exposition time are assumed as production parameters to optimize, whereas EPM/EPDM final tensile strength is considered as objective function.The GA approach proposed exploits a specifically crafted zooming strategy, consisting in the subdivision of the population at each iteration into two sub-groups, depending on individual's grade of fitness (elitist strategy). Different genetic procedures are applied to the sub-groups, consisting of both two typologies of admissible mutations for the elite sub-population and mutation and reproduction for the remaining individuals. In order to improve algorithm convergence, a user-defined population percentage, depending on individual's fitness, is replaced with new phenotypes at the end of each iteration, enforcing in this way the chromosomes renewal.In order to test the reliability of the method proposed, a technical meaningful case study consisting of a high voltage cable used by Italian Railways and cross-linked with a number of different peroxides is discussed. Numerical results show that particular care has to be used by practitioners in the choice of nitrogen temperature and exposition time of production lines to obtain high quality products.     

柱塞卡滞原因分析

某柱塞泵工作中发生柱塞卡滞,经显微形貌观察、光谱分析、电子探针面扫描分析和显微硬度分析等,确定柱塞卡滞的根本原因为原材料组织中存在严重的网状共晶碳化物,降低了强度和韧性,增大了柱塞球面表层的脆性,进而导致了球面部位的接触疲劳抗力下降。严重的疲劳磨损与接触疲劳造成了柱塞球面脱层破坏,由此产生的金属碎屑进入柱塞与衬套的配合间隙处,进而限制了柱塞的自由运动。     

20Cr钢单向器轴破裂原因分析

20Cr钢单向器轴在试车时发生破裂,通过化学成分分析、宏观和微观检验对破裂原因进行了分析。结果表明：单向器轴的渗碳层深度过深,马氏体和碳化物级别严重超标。碳势过高、热处理过热导致淬火时开裂是零件破裂失效的根本原因。     

氰凝在防腐、防渗漏工程上的应用

防腐、防渗漏的处理是一个很棘手的问题，作为一种新型的灌浆材料氰凝在工程的防腐、防渗漏的实践中取得了显效果。     

梅花形孔板支撑换热器壳程流场的数值分析

提出了梅花形孔板支撑换热器壳程的单元简化模型,应用CFD软件FLUENT对换热器进行数值分析,得到流场、温度场的细观信息,通过不同跨距折流板的数值模拟,拟合出相应公式,为梅花形孔板支撑换热器的结构优化设计提供了依据.     

网状孔板纵向流换热器壳程流体流动及换热特性的数值模拟

应用CFD软件对网状孔板换热器壳程流体流动及换热特性进行了数值模拟研究,揭示了网状孔板强化传热的机理,分析了孔板间距及开孔率对其换热、压降性能的影响,推导出网状孔板纵向流换热器壳程换热与流动的准数关系式. 结果表明,流体流过网状孔板产生射流及二次流现象,强化了壳程流体的传热;在Re=2300~6300范围内,网状孔板换热器比弓形折流板换热器的Nu数增大约50%,但压降比弓形折流板换热器高约2.5倍;在研究范围内,孔板间距减小、开孔率减小均能使壳程流体的Nu数及压降增大,且Re数越大,开孔率、折流板间距对Nu数及压降的影响越大;但随开孔率、折流板间距减小,流体压降增加的速度明显比Nu数快.     

分布式电源配置研究

分布式电源的引入改变了配电网的结构,对配电网的网络损耗有很大的影响,需要对分布式电源进行合理配置。针对单支路馈线模型在3种负荷类型下,同时考虑分布式电源接入位置和接入容量2个因素,以最小化馈线损耗为目标提出了分布式电源配置的方法;针对网状系统,提出了一种新的基于节点有功功率网损灵敏度的单DG配置算法．并利用算例仿真验证了算法的可行性。结果表明,这些方法可更加高效精确地实现分布式电源的最优配置。     

网状孔板纵向流换热器壳程流体流动及换热的三维数值模拟

利用Fluent软件对网状孔板纵向流换热器壳程流体流动及换热进行了三维数值模拟,得到了壳程流体温度场、速度场及压力场等细观信息。根据模拟的结果,揭示了网状孔板强化壳程流体换热的机理,分析了壳程流体沿轴向流动及换热的性能,总结了近壁区流场及温度场的特点。     

川藏公路东久河下游段路基水毁防护工程对策

针对川藏公路东久河下游段特殊水文水力条件和自然环境特征，选择(K4113 280～K4113 365)典型水毁段为例，对该段路基水毁的形成因素、特征、活动规律及公路路基水毁防护经验教训分析，根据野外路基防护工程冲刷模拟试验，建立适合该段路基护墙冲刷深度计算公式，在保证足够基础埋深的基础上，提出了浆砌石挡土墙 钢丝网混凝土护坦的长期(永久性)防护工程方案，为西藏高山峡谷区沿河路基水毁防护工程建设提供了示范。