城市单向交通系统的应用研究--以长春市为例

在保持原有道路交通路网的条件下,单向交通是改善大中城市交通堵塞状况的经济而有效的方法之一.通过对单向交通及长春市交通路网情况分析,阐明长春市采用单向交通的优势、存在问题并提出完善长春市单向交通系统的建议.     

交通拥堵现象背后的社会问题

分析了北京交通拥堵的症结,论述了应遵循的交通理念,提出了改善交通拥堵的建议.     

北京交通拥堵症结分析

分析了北京城市交通拥堵的原因,提出了解决这一问题的思路.     

Port traffic risks – A study of accidents in Hong Kong waters

This paper investigates port traffic risk issues by discussing historic accidents in Hong Kong port. A total of 2012 marine accidents with 94 deaths were reported in Hong Kong waters in year 2001–2005, while 660,427 oceanic ships visited the port. A negative binomial regression model is used to analyze the record of dataset. It is found that port traffic risks are of certain pattern and collision accidents are the most popular incidents when port traffic is heavy. Passenger-type vessels have higher potential for injuries during accidents. The findings have identified statistically significant factors for improvements in managing port traffic risks.     

基于SSR和ADS-B混合监视的机载编队防撞系统设计

由于设备性能的限制,民航飞机目前使用的机载防撞系统TCASⅡ不能适用于编队飞 行防撞。为了解决飞机编队飞行防撞以及与民航飞机TCASⅡ兼容的问题,给出了一种基 于二次雷达(SSR)和ADS-B混合监视的机载编队防撞系统的设计方案。该方案采用了TCAS主动 监视和被动监 视相结合的方法,利用唯一的24位S模式地址来识别和归类目标飞机,将TCAS的监视数据和A DS-B的监视数据进行数据融合来完成对目标飞机的监视和跟踪。通过将大型编队划分为多个 编队单元的方法,由长机负责保持各个编队单元之间的安全间距。采用收发器将长机产生的 位置保持和碰撞避免的操纵指令通过高频数据链路传送给各个编队单元,各个编队成员按照 操纵指令调整自己飞机的位置,完成对整个编队的位置保持和碰撞避免的集中控制和分散执 行。该方案可以为机载编队防撞系统的设计和实现提供参考和帮助。     

An analysis of highway work zone safety practices in Pakistan

Highway Work Zones (HWZs) present a major hazard for road users, construction workers and equipment, and significantly contribute to occurrence of road crashes worldwide. The present study focuses on analysing the current state of safety measures at HWZs in Pakistan. A more direct approach is adopted by comparing safety measures at randomly selected HWZs in Pakistan with well-established safety procedures in Manual on Uniform Traffic Control Devices (MUTCD). HWZ safety measures such as traffic signs, markings, safety measures for pedestrians, workers and construction machinery, police enforcement, speed control measures, provision of advance warning area, buffer spaces, transition areas, and tapers for eight different HWZs were studied and compared with MUTCD standards. The results revealed that majority of the HWZs in Pakistan do not conform to any standard layout especially for safety and speed control measures. An enhanced need for special efforts towards improving safety at HWZs in Pakistan is highlighted.     

改善北京大型平交路口交通拥堵状况的建议

作者认为 ,造成北京大型平交路口交通拥堵的原因之一是由于非机动车道设置不尽合理而造成的机动车和非机动车的相互干扰。要解决此问题 ,从长远看需从城市和交通规划等宏观层面解决深层问题 ;近期解决问题的基本思路是缩短行人和自行车过路口的距离 ,并相应调整路口交通设施和规则 ,已减少交叉点 ,疏导拥堵。     

Back to Basics: Forecasting the Revenues of Internet Firms

This paper examines the roles played by past revenues, web usage data, and analysts in forecasting the future revenues of internet firms during the years 1998 to 2000. For this time period our analysis shows that estimates of web traffic growth have significant incremental value in the prediction of revenues above time-series forecasts. Furthermore, analysts almost always underestimate the revenues of internet firms. Historical revenue growth has incremental predictive power over analysts' forecasts for portal and content/community firms, but not for our e-tailer sample. Moreover, the stocks of the portal and content/community firms with high historical revenue growth earn higher abnormal returns during our sample period than do those with low historical growth. Estimates of web usage growth generally do not have incremental value over analysts' forecasts for predicting the revenues of either set of firms. However, perfect foreknowledge of actual web usage growth would provide incremental predictive power. Collectively, our findings point to the potential value for forecasting purposes of both improving upon the web usage estimates and obtaining more timely reports of actual web traffic.     

对我国重交沥青市场大转折的思考

从20世纪90年代我国开始兴建高速公路，对重交沥青的需求量日趋增多。1999年进口的重交沥青高达1470kt，2000年我国重交沥青的产量为2130kt，进口量下降到1390kt，标志着我国的重交沥青市场出现了重大转折，但国产沥青还存在着：（1）质量不稳定；（2）对改性沥青的重视还不够；（3）销售形式落后；（4）品牌众多等问题。由此建议：（1）保证重交沥青的质量；（2）加快改性沥青的研究和生产;(3)改变销售观念；（4）统一品牌。     

劣质减压渣油加工方案探讨

由中东原油生产的劣质减压渣油，可作为延迟焦化原料，也是生产沥青的好原料。文章重点探讨了沥青生产的工艺路线，脱沥青油的处理，以及在沥青产品处于淡季时，将沥青与减渣掺混后作延迟焦化原料的可行性。文章以某企业的减压渣油为例，考虑了3种加工方案。方案1：减压渣油全部作延迟焦化原料；方案2：减渣抽出一部分去丙烷脱沥青，脱沥青油去加氢裂化，脱油沥青与减渣掺混后作延迟焦化原料；方案3：减渣抽出一部分去丙烷脱沥青，脱沥青油去加氢裂化，部分脱油沥青与少量减渣调合后生产重交通道路沥青产品，其余减渣与脱油沥青去延迟焦化。通过对以上3种加工方案的技术经济分析，认为方案3经济效益较好。