弱层抗剪强度参数对边坡安全系数的影响分析

露天煤矿边坡常沿弱层发生滑动,弱层的抗剪强度直接影响到边坡的稳定程度。以元宝山露天煤矿南帮边坡为应用实例,分析了含水率对弱层抗剪强度参数的影响,得出内摩擦角、内聚力与含水率基本符合负指数关系的结论。在此基础上,分析了不同含水率条件下弱层的抗剪强度参数对边坡安全系数的影响,得出安全系数随内摩擦角、内聚力的增大而增大,安全系数对内摩擦角更灵敏的结论,从而为制定元宝山露天煤矿南帮边坡的滑坡防治措施提供了重要依据。     

基于案例的光伏电站总图设计与分析

阐述光伏电站的设计、总图布置及光伏电站建成的影响,旨在为更多类似工程实践提供参考。     

死于2014?

正深圳的冬日并无寒意,但我仍感觉到冷。因为在2014年第一天,我想到了"死"。也许有人说,新年伊始,这个字多不吉利!但是关于这个话题,谁又能置身事外。热情的诗人高唱生命的恋歌,然而冷静的哲学家却说:死亡是自然法则的胜利。当然,我并非要无缘无故地谈到"死",只是一段时间以来"纸媒必死"的论调甚嚣尘上,而最近让这一论调发酵的是上海报业集团旗下《新闻晚报》宣布新年停刊的消息。相对于许多人叨叨纸媒不行了的人云亦云,也有人在冷静分析真实的原因,除了上海报业集团资源整合和结构调整的观点,我还倾向于一种说法:死掉的不是纸媒,死掉的是陈旧的思维模式和不愿改     

改性TiO_2光催化剂的研究进展

通过叙述TiO2光催化剂的反应机理,分析由于自身因素(晶型、粒径)而影响光催化性能。针对目前研究较成熟的掺杂和负载这两种改性方法作以综合论述,并提出光催化剂改性的其他途径及前景。     

坚硬致密石英岩地层用新型胎块钻头的研究与应用

在钻探施工中,当钻遇坚硬致密石英岩时,金刚石钻头普遍存在钻进效率低、打滑及进尺困难的现象。针对这种地层,研制了新型胎块孕镶钻头,通过胎体配方的改进,水路及金刚石品级、浓度的优化设计,在施工现场取得了良好的钻进效果。详细介绍了适用于该种地层的新型胎块钻头的设计及现场应用效果,为类似钻探施工提供参考。     

Particle-in-cell simulation for effect of anode temperature on discharge characteristics of a Hall effect thruster

Propellant gas flow has an important impact on the ionization and acceleration process of Hall effect thrusters (HETs). In this paper, a particle-in-cell numerical method is used to study the effect of the anode temperature, i.e., the flow speed of the propellant gas, on the discharge characteristics of a HET. The simulation results show that, no matter the magnitude of the discharge voltage, the calculated variation trends of performance parameters with the anode temperature are in good agreement with the experimental ones presented in the literature. Further mechanism analysis indicates that the magnitude of the electron temperature is responsible for the two opposing variation laws found under different discharge voltages. When the discharge voltage is low, the electron temperature is low, and so is the intensity of the propellant ionization; the variation of the thruster performance with the anode temperature is thereby determined by the variation of the neutral density that affects the propellant utilization efficiency. When the discharge voltage is high, the electron temperature is large enough to guarantee a high degree of the propellant utilization no matter the magnitude of the anode temperature. The change of the thruster performance with the anode temperature is thus dominated by the change of the electron temperature and consequently the electron-neutral collisions as well as the electron cross-field mobility that affect the current utilization efficiency.