The use of demand correlation in the modeling of air carrier departure delays as first‐order autoregressive random processes

A method for modeling air carrier departure delays at commercial‐service airports as autoregressive random processes is presented. This method employs the correlation of a priori demand data to significantly reduce prediction error in the optimal least‐squares estimator for additive white noise. The reduction factor of the prediction error is demonstrated to be on the order of 10² over that of the unbiased estimator. Copyright © 2011 John Wiley & Sons, Ltd.     

Optimization of transport investment and pricing policies: the role of transport pricing in network design

This paper investigates the role of transport pricing in network design and describes two facts about flow pattern in a transportation system. The first, illustrated by an example of Braess paradox, is that adding a new link to the network does not necessarily minimize the total travel time. The second is that introducing of appropriate toll pricing may reduce not only the total network time but also the travel time for each individual traveller. It follows with the investigations of different system objectives and different pricing policies (only toll pricing and distance‐based pricing are considered), and shows how they affect the system performance and flow pattern. Lastly, a systematic optimization process is proposed for integrated planning of transport network and pricing policies.     

瑞利面波椭圆极化在盾构隧道地层扰动探测中的应用

为解决传统物探方法在城市盾构隧道工程中难以对地层扰动达到较好探测和监测目的，提出了主动源瑞利面波椭圆极化方法. 采用二维有限元数值模拟对实际盾构隧道施工背景下的地层情况进行全波场正演模拟，并对其波场传播、速度频散和椭圆极化频散等特征进行分析；结合工程实例，进一步将椭圆极化方法和传统速度频散方法进行对比研究. 研究结果表明:主动源瑞利面波椭圆极化方法在探测地下介质结构分布及监测地下空洞等异常结构的变化方面具有和传统速度频散方法同样的探测效果，但由于其不需要长大检波器排列，对周围环境震动等噪声抗干扰能力相对较强，因此更适合城市等场地受限和具有一定震动和噪声干扰的环境，从而具有更广阔的应用前景.      

In situ colonization of marine biofilms on UNS S32760 duplex stainless steel coupons in areas with different water qualities: Implications for corrosion potential behavior

In the presence of biofilms, stainless steels （SS） exhibits an increase in corrosion potential, called ennoblement. In the present study, the corrosion potential （Eco,） behavior of the duplex SS UNS S32760 was recorded simultaneously with the in situ marine biofilm formation in two areas at Arraial do Cabo, Southeastern Brazil. The biofilm at Forno Harbor （an anthropogenically disturbed area） was characterized by higher relative abundances of Bacteria at day 2, followed by diatoms （especially Navicula sp.） on day 10 and dinoflagellates on day 18, whereas no clear trend was recorded at Cabo Frio Island （an undisturbed area）. The ennoblement of Ecor values was site-dependent. In a complementary laboratory assay, biofilms were removed and the Eco values registered in sterile conditions for the subsequent 10 days and corroborated in situ results. Understanding biofilms and SS interactions has important implications for materials science and engineering decisions as well as helping to fill in imnortant gaps in this knowledge.     

桥梁钢结构防腐涂装体系的选择

随着国家基础设施建设速度的加快,大型钢结构桥梁不断涌现。针对腐蚀和腐蚀疲劳问题而开展的钢结构防腐涂装研究日渐受到人们的关注。文中介绍了桥梁钢结构防腐的发展现状,论述了钢结构桥梁防腐涂装体系的选择和确定方法。     

495ZLQ柴油机参数匹配与性能计算分析

利用发动机模拟计算软件BOOST建立了495ZLQ柴油机的计算分析模型,探讨分析了不同增压器型式、排气管结构、压缩比及供油提前角等匹配参数对整机性能的影响,并确定了较合适的匹配参数。对选定的柴油机优化方案进行了标定转速3 200 r/min和最大扭矩转速2 200 r/min下的负荷特性模拟计算分析与试验验证。结果表明,模拟计算结果与试验值较为一致,柴油机性能符合预定的目标,为该柴油机改进设计与试验研究提供理论依据和研究方向。     

Damper Models for Heavy Vehicle Ride Dynamics

A laboratory rig for testing hydraulic dampers using the 'hardware-in-the-loop' method is described, and the accuracy of the test method is investigated. A mathematical model of a hydraulic shock absorber is then developed. The model is suitable for vehicle simulations and has seven parameters which can be determined by simple dynamic measurements on a test damper. The shock absorber model is validated under realistic operating conditions using the test rig, and the relative importance of various features of the model on the accuracy of vehicle simulations is investigated.     

宜万铁路别岩槽隧道F3 断层突发性涌水治理

宜万铁路别岩槽隧道F3断层在初期支护完成后,由于受地表强降雨影响,突发大规模涌水,使初期支护严重变形。文章主要介绍了F3断层的涌水事故、应急预案,以及通过采取“径向注浆加固-初期支护加强-及时施作二次衬砌”等综合技术措施,有效地治理了F3断层涌水-变形段。     

Short-term Hourly Traffic Forecasts using Hong Kong Annual Traffic Census

The need for acquiring the current-year traffic data is a problem for transport planners since such data may not be available for on-going transport studies. A method is proposed in this paper to predict hourly traffic flows up to and into the near future, using historical data collected from the Hong Kong Annual Traffic Census (ATC). Two parametric and two non-parametric models have been employed and evaluated in this study. The results show that the non-parametric models (Non-Parametric Regression (NPR) and Gaussian Maximum Likelihood (GML)) were more promising for predicting hourly traffic flows at the selected ATC station. Further analysis encompassing 87 ATC stations revealed that the NPR is likely to react to unexpected changes more effectively than the GML method, while the GML model performs better under steady traffic flows. Taking into consideration the dynamic nature of the common traffic patterns in Hong Kong and the advantages/disadvantages of the various models, the NPR model is recommended for predicting the hourly traffic flows in that region.     

亚硝胺

与二烯烃橡胶相比，EPDM的双键很少：为了提高EPDM胶料的硫化速度，需要加入大量的促进剂。由于某些促进剂中含有仲胺，这是亚硝胺的主要来源，因此人们正在考虑使用一类新的促进剂。考察了不同硫化体系对亚硝胺排放、加工参数和物理性能的影响，片采用试验设计方法对硫化体系进行了优化。