活塞式压缩机故障诊断方法

在分析活塞式压缩机常见各类故障及诊断方法的基础上,研究热力参数法、振动声学法和油液分析法的工作原理、实施难点及适应范围,为采用适宜的方法诊断活塞式压缩机故障提供选择的基础．     

A model to identify airport hubs and their importance to tourism in Brazil

Air transportation in Brazil has been recently liberalized and one of the consequences of this process is the concentration of flights in a few hubs. During the years 2006-2007 two fatal accidents created unprecedented chaos in both land and air sides of the system with harmful consequences to tourism in Brazil. The consequences were more airport congestion and many episodes of flight delays and cancellations that lasted for several months. We argue that, among other factors, this state of blackout was a result of the increase in the degree of concentration in few airports, particularly Congonhas (in São Paulo) and Brasília. Using data obtained from a survey with Brazilian experts, a comparison was made with two existing methods (the one used by the US Federal Aviation Administration and the usual Herfindahl-Hirschman method) in order to calculate the number of hubs in Brazil. Due to the huge discrepancy obtained between data from the survey and the other two methods considered, a new mathematical method based on the Herfindahl-Hirschman Index was proposed to identify the number of hubs in a given network. Drawing from the examples of what happened to tourist destinations during and after the air transport crisis in Brazil, the article concludes discussing the need for a more accurate tool to identify and to monitor the concentration of flights at the Brazilian air transportation network and its importance to tourism.     

论我国城市公交电动客车的开发

迈入新世纪,防治城市空气污染的紧迫重任摆在国人面前。据环保部门统计:城市空气污染源的60%以上来自交通运输车辆的废气排放。本文就开发我国零污染的城市公交电动客车作探讨性的论述。     

基于现代设计手段的某车用增压器离心压气机设计

针对发动机高压比宽流量范围需求,作者采用两区模型性能预测,控制载荷分布叶片造型和提高自振频率等技术,开展某车用增压器跨声速离心压气机设计和试验验证研究.并得出如下结论:①两区模型性能预测技术可快速预测压气机特性,其结果与试验吻合较好.②控制载荷叶片造型技术可快速方便应用于工程研制,设计结果比较理想.③相同大小叶轮,改变叶轮进口直径,在保持压比和效率近似恒定的情况下,可获得不同流量范围的压气机特性.④减小叶轮出口宽度和增大扩压器收敛段长度在某种程度上可推迟发生亚声速流动喘振.⑤压比大于3后(跨声速状态),压气机流量范围会突然变窄,喘振流量会大幅度增大.     

Personal exposures to PM during short distance highway travel in India

Traffic is the largest contributor (37%) to urban air pollution in India. During commuting, passengers are significantly exposed to pollutants. We carried out a study on a National Highway (NH) in India to measure personal exposure to Particulate Matter (PM) in five travel modes. PM_2.5 concentrations showed the following trend: Bus > Car FA (fresh air mode of air condition) > Bus AC > Car > Car RC (re-circulation mode of air condition). Highest and lowest concentrations of PM₁₀ were observed in Bus (134 ± 47 µg m⁻³) and Car RC (20 ± 5 µg m⁻³), respectively. The exposures were highest at the rear seats during the Bus AC journeys. In Car FA, the contribution of PM₁ to total concentrations was dominant (61%). Travel modes explained highest variabilities in PM₁₀, PM_2.5 and PM₁ concentrations. In all travel modes, the highest particle counts were observed for PM_0.3–0.5. PM_>0.5–5.0 counts during Bus journeys were comparatively higher than remaining modes. Deposition doses of passengers were as high as 3.22 µg of PM₁₀ (in Bus), 0.66 µg of PM_2.5 (in Bus) and 0.06 µg of PM₁ (in Bus AC) during the ~1 h journey. Our study revealed that Car RC is the safest mode of travel, both in terms of personal exposures and PM depositions in respiratory system. The results from this study can be used to target efforts to reduce personal exposure of highway commuters.     

750t水驳采用气囊力式下水

水驳的建造相对来讲比较简单,但建造后如何下水成为我们修船厂的一个难点,采用重力式下水设备简单,同时具有安全方便操作等特点。     

急性中毒现场及特殊作业场所气体采样方法

为适宜急性中毒现场和特殊作用场所的气体采样而设计了导向采样法。该法以金属活塞三通为气体导向控制器,与采气管,连接管,抽气动力,样品收集器共同组成采样系统。导向采样法设计合理,经多年现场应用,操作简便安全,采集的气样准确可靠。为急性中毒原因调查及特殊作业场所劳动卫生学评价提供了可行的采样方法。     

欧洲的舰载防空与反潜武器系统

为了护卫下一代新型航空母舰,欧洲各国海军正合作开发护卫舰上的舰载防空与反潜武器系统。其中,法国、意大利联合建造的“地平线”护卫舰和英国45型防空护卫舰将装备用于防空和反潜的各种武器系统。另外,西班牙和挪威的护卫舰也各装备了美国和欧洲研制的各种先进武器。     

Time to burn: Flight delay,terminal efficiency,and fuel consumption in the National Airspace System

Improved Air Traffic Management (ATM) leading to reduced en route and gate delay, greater predictability in flight planning, and reduced terminal inefficiencies has a role to play in reducing aviation fuel consumption. Air navigation service providers are working to quantify this role to help prioritize and justify ATM modernization efforts. In the following study we analyze actual flight-level fuel consumption data reported by a major U.S. based airline to study the possible fuel savings from ATM improvements that allow flights to better adhere to their planned trajectories both en route and in the terminal area. To do so we isolate the contribution of airborne delay, departure delay, excess planned flight time, and terminal area inefficiencies on fuel consumption using econometric techniques. The model results indicate that, for two commonly operated aircraft types, the system-wide averages of flight fuel consumption attributed to ATM delay and terminal inefficiencies are 1.0–1.5% and 1.5–4.5%, respectively. We quantify the fuel impact of predicted delay to be 10–20% that of unanticipated delay, reinforcing the role of flight plan predictability in reducing fuel consumption. We rank terminal areas by quantifying a Terminal Inefficiency metric based on the variation in terminal area fuel consumed across flights. Our results help prioritize ATM modernization investments by quantifying the trade-offs in planned and unplanned delays and identifying terminal areas with high potential for improvement.     

某型船用空压机虚拟拆装系统研究与开发

虚拟现实技术已经广泛应用与各个领域。将虚拟现实技术应用到操作训练中,不仅可以降低训练成本,而且不用受制于场地的限制。本文设计并实现了基于VC和EON的船用空压机虚拟拆装训练系统,通过EonX控件实现EON和VC之间的通信,并且将学生的训练信息记录在数据库中,可以根据记录的信息进行有针对性的训练,起到较好的训练效果。