Influence of thermodynamic activities of different masteralloys in pack powder mixtures to produce low activity aluminide coatings on TiAl alloys

Titanium aluminides are interesting high temperature materials, but show insufficient oxidation resistance as well as embrittlement at higher temperatures (>750 °C). Al-enriched coatings can be manufactured by pack cementation on many high temperature alloys to promote the formation of a protective alumina layer at high temperatures, which not only protects the alloy from oxidation but is also expected to impede embrittlement of TiAl at high temperatures. One drawback of such coatings is that Al-rich phases are very brittle. Therefore the major intermetallic aluminide phase in the coating plays a critical role for the protection behavior. Based on thermodynamic calculations different masteralloys were chosen to control the pack cementation process. Particular attention is given to the gradient between the aluminum activity of the different masteralloy powders and the aluminum activity of the substrate surface (alloy TNM^®-B1) in order to control the deposited phase at the surface. It is revealed that powder pack with Al as masteralloy provides a high Al activity and produces thick multi-layered coatings consisting of brittle TiAl₃ and TiAl₂ phase and aluminum-rich TiAl. By using different chromium aluminides as masteralloys, thinner, low-activity coatings could be produced, consisting of a bi-layer of brittle TiAl₂ phase and aluminum-rich TiAl or just the targeted pure aluminum-rich TiAl, which is known to have much better mechanical properties.     

Investigation on concentration characteristics of ozone micro-bubbles fixed in ice and ozone gas released from ice

Ice formed from water in which ozone gas is dissolved is promising for the cold storage of foods because of the ozone's sterilization and deodorization capabilities. However, effective dissolution of ozone gas in water and taking ozone gas into ice are not easy. Furthermore, the decomposition rate of the ozone itself is usually very fast, regardless of its phase. Thus, to effectively take ozone gas into ice, the authors have developed ice containing ozone micro-bubbles. In this paper, ice containing ozone micro-bubbles formed by adding surfactant was kept for a desired time at a desired constant temperature without melting of the ice. The concentration of ozone micro-bubbles fixed in ice and the ozone gas concentration released from ice by melting were measured to investigate the ozone decomposition rate due to fixation in ice and the characteristics of the released concentration. Furthermore, the influences of surfactant on both concentrations were examined.     

地下工程力学综合集成智能分析的理论和方法

应用人工智能、神经网络等新兴学科理论，提出了地下工程力学综合集成智能的分析方法。着重探讨了地下工程力学综合集成智能分析的基本模型、智能岩层控制系统模型、一种新的不确定性推理方法、岩体区域等价本构模型的自适应识别新方法。初步工程实践表明，它具有先进性和科学性，可以应用于处理复杂的岩石工程问题。     

主动配电网源荷协调多目标阻塞调度

随着电动汽车的规模化发展,其所具备的灵活充放电时间转移能力,使得电动汽车充放电秩序的选择成为影响主动配电网出现负荷尖峰的一个重要因素,大量电动汽车无序集中用电,甚至会引起网络阻塞。文中基于中国电力市场的实际情形,结合电动汽车群充放电的柔性与主动配电网中可控分布式电源发电出力的灵活性,将电动汽车群、可控分布式电源,以及从大电网的购电量作为调度对象,以电动汽车群充放电费用最少和系统发电成本最低为目标,提出一种充放电服务费调整策略下的主动配电网源荷协调多目标阻塞调度模型。算例验证表明,所提出的阻塞调度策略可降低系统阻塞效应、提高电网运行安全性和经济性。     

基于自适应滑模层极值搜索的光伏发电最大功率跟踪方法

保证光伏阵列快速到达最大功率点并且能稳定运行,一直以来是光伏发电研究领域关注的重要问题之一。为此,文中提出了基于参数自适应调整滑模层极值搜索控制的光伏发电系统最大功率跟踪新方法。首先证明了基于滑模极值搜索的光伏发电系统最大功率跟踪控制策略的稳定性;然后提出采用具有更低控制频率及更低控制噪声的滑模层函数代替简单的开关函数。在此基础上,进一步提出了控制参数的自适应调整方法,使得控制系统在具有较好的控制品质的同时,避免了繁琐的人为参数调整。算例证明了所提方法的有效性。     

基于泥沙冲淤数值模拟的水库调度方案研究

以东台子水库为研究对象,基于一维不饱和全沙数值模型,研究蓄洪运用方案、蓄洪排沙运行方案、分阶段蓄洪运用方案、蓄清排浑运用方案等四种水库调度方式下的泥沙淤积情况,力图在兴利防洪的基础上尽量利用弃水排沙,保持有效库容。对不同运行年限的淤积量、水库库容变化和排沙比等要素的模拟研究表明,分阶段蓄洪运用或蓄清排浑运用方案更有利于保持有效库容,对延长水库使用寿命具有一定作用,是较优的水库排沙优化调度方案。     

中水深度处理技术在火电厂的应用

为满足工艺要求,选择城市中水作为火电厂循环冷却水补水需对其进行二次深度处理。探讨石灰石凝聚处理技术应用于城市中水深度处理,介绍了该技术的原理及工艺流程,并对BOD5、CODcr、悬浮物、碱度、硬度TP等的去除进行了论证。该工艺具有可靠性高、自动化水平高、运行费用低、日常检修维护量小的特点,并且一次性投资小、回报周期快,具有较好效益。     

智能变电站数据源端维护技术方案探讨

变电站实现智能化的关键是实现全站数据统一建模.采用IEC 61850实现全站数据统一建模使数据源端维护成为可能.介绍了智能变电站数据源端维护的概念,并针对当前的技术条件及未来可能的技术发展提出了实现数据源端维护的多种解决方案.     

沈北、大庆混合减四线脱蜡油NMP精制及选择性系数求取

以沈北、大庆混合减四线脱蜡油为原料,进行NMP单级抽提试验,借助数学手段得到最优操作条件.NMP精制的最佳操作条件为:剂油比1.38(m/m),抽提温度60.8℃,含水量2.1%.在此操作条件下,精制油的收率为88.74%,60℃折光率为1.4776,黏度指数95.27.采用柱色谱法分析减四线脱蜡油族组成,测出所得四组...