应重视军民通用型舰船开发及应用技术研究

从和平时期军用舰船的有效利用和战时舰船的大量消耗，以及如何降低舰船的建造费用、如何减少舰船现代化改装时的难度和费用及民用船只的征用等多方面论述了开展“军民通用型舰船开发及应用技术研究”的重要意义，并针对军民通用型舰船研究提出了建议和看法。     

Air pollution impact of maritime shipping operations in the port of Houston

Abstract

Major air pollutants from maritime shipping operations are sulfur oxides, nitrogen oxides, and particulate matter emissions from combustion of fuel oil during cruise, berth, and start‐up modes. Sulfur oxides emissions are substantial from steamships burning high‐sulfur residual fuel oil, where shipping contributes 66 percent of the total sulfur dioxide emissions from transportation sources, and almost 3 percent of the total for Harris county, Texas. Nitrogen oxides emissions are significant during cruise conditions for both steamships and motor ships, while particulate emissions are substantial during start‐up and tube cleaning.

Significant marine air pollutant emission sources are found in busy harbor areas such as the Houston Ship Channel. Offshore terminals for unloading large tankers may result in emissions of 10 to 20 tons of sulfur oxides daily per ship, and 3 to 5 tons of nitrogen oxides daily per ship during pumping operations. Trace‐metal constituents present in the oil may catalyze sulfur dioxide and nitrogen dioxide oxidation to their respective sulfate and nitrate aerosols in the humid Texas Gulf Coast atmospheres to aggravate photochemical air pollution problems once the air masses reach industrial and populated urban areas on land. Onshore sulfur dioxide and particulate‐matter emission controls may be necessary for some large ships in port to minimize potential impact on coastal zone air quality.     

某高速公路岔道口桥梁有限元分析及配筋研究

结合某高速公路岔道口桥梁的实际情况,应用大型有限元MIDAS软件建立岔道口桥梁的梁格空间模型对岔道口受力进行仿真分析,并运用ANSYS软件建立实体模型与梁格模型在自重情况下的结果进行对比,根据应力分布特点对结构进行配筋研究,取得了传统平面计算无法获得的结果。     

吴淞江大桥桥墩抗船撞能力评估研究

针对吴淞江大桥主桥P1#、P2#桥墩用Midas软件建模,分别计算了桥墩在受到1000kN横桥向、顺桥向水平撞击力时在桥墩最危险截面处产生的内力。根据桥墩的实际配筋,按照《公路钢筋混凝土及预应力混凝土桥涵设计规范》,计算桥墩实际能够承受的水平撞击力。横桥向水平抗力由P1#桥墩桩基强度控制,为8890kN;顺桥向水平抗力由P2#桥墩强度控制,为7944kN。应用有限元软件ANSYS／LS—DYNA建模分析在高水位时1000t级船舶正撞、侧桥向45°撞击桥墩产生的最大撞击力。根据计算结果评估桥墩的抗船撞能力。     

燃煤热载体炉的冗余控制系统设计

在许多重要工业应用场合,需要长期、连续、安全可靠的控制保障。冗余控制是一种解决方案,在SIEMENS的S7系列PLC中,有S7—400H的硬冗余和S7—300的软冗余2种解决方案。文中介绍的是另一种解决方案,即用S7—300和S7—200控制器共同实现的热载体炉的冗余控制。比起前2种方案来,本方案更经济,冗余范围更大,但仅限于允许2套系统切换时间在几秒或更长一点的非无人值守的过程控制系统中。     

游艇导航技术领域的下一场重头戏

——大量的娱乐休闲型游艇导航技术从大船成熟的应用技术中脱颖而出。最新型的自动识别系统（AIS）可谓其中最为重要的精萃产品。[编者按]     

Organizational form and performance in urban mass transit

Ownership and management for urban mass transit organizations have taken many forms over the years, with publicly‐owned and managed systems now dominant. In recent years, however, strong economic and political forces have increased pressures for privatizing urban mass transit services. This review analyses 20 studies from three countries (predominantly the U.S.A.) on the relationship between organizational form and fixed‐route bus transit performance. It concludes that previous research has not made a persuasive case for the whole‐scale privatization of either ownership or management of urban mass transit organization. Conclusions here are intended to apply to the U.S.A. as well as other countries with mixed enterprise systems in which choices about organizational form may have some consequence for performance.