桥梁伸缩缝冬季施工技术要点

在我国北方地区,由于工程实际需要,通常要求在冬季完成伸缩缝的施工工作。在低温干燥的恶劣自然环境下,要求冬季施工必须采取一些特殊的措施以保障工程质量,较系统地阐述和总结了冬季桥梁伸缩缝施工预留缝宽计算调整及混凝土拌制养护。     

A fuel tankering model applied to a domestic airline network

This paper presents a linear programming model designed to determine the optimum fuel loading quantities along a route network for a Brazilian domestic airline. Assuming that there are no volume purchase or storage capacity restrictions on each station, the analysis is carried out for one aircraft on one day of its schedule. Results are extrapolated for a monthly and yearly basis. Through the proposed model, it is seen that such a fuel tankering technique leads to a 5% economical saving, but produces a 1% additional fuel burn. A discussion on the environmental impact for this procedure is also proposed. Copyright © 2011 John Wiley & Sons, Ltd.     

基于有限元计算的码头凹凸缝结构配筋和防护设计

由于凹凸缝为非杆件结构,不能直接依据JTS 151—2011《水运工程混凝土结构设计规范》计算结构内力,而基于连续介质力学的有限元方法则可以很好地分析钢筋混凝土结构的内部应力.运用Robot有限元软件构建模型,将整个码头简化为弹性支撑的连续梁,通过计算连续梁内力得到凹凸缝结构所受外力,进而计算凹凸缝结构内部应力分布,最后依据计算结果和相关规范对凹凸缝结构进行配筋和防护设计.该设计方法自2008年工程实际应用至今,效果良好.     

A ‘Less-flexibility-first’ Heuristic for the Placement of Inland Vessels in a Lock

Abstract

Inland vessels move goods along waterways (canals and rivers) and they visit ports. Because of their tidal nature, vessels make use of locks to enter ports or waterways. From a port management point of view, fast access to and from the port and high utilization of locks are important objectives. Where the former relates to low inbound and outbound waiting times, the latter relates to the placement of as many vessels as possible in the lock before its operation. This article includes a case study that relates to the operation of the Van Cauwelaert lock in the port of Antwerp, Belgium. Lock operation policy is as follows: vessels wait in front of the lock for a port administrator to assign places in the lock based on knowledge of the vessels’ dimensions. As such, there is no FIFO-discipline, but a ‘group-FIFO’-discipline, i.e. if n vessels are allowed into the lock, they are the first n vessels in the arrival queue. A heuristic algorithm is formulated for the placement of vessels in the lock. This algorithm supports the decision where to place the vessel in the lock, aiming to place as many vessels as possible from the arrival queue. At the same time, it supports the decision to start a locking operation or not, based on information about vessels that are announced but which have not yet arrived at the lock's entrance. The heuristic is called a ‘less-flexibility-first’-heuristic as it looks for pseudo-placements, showing which flexibility is left for the remaining vessels after placing a vessel. This article describes the implementation of the heuristic and provides numerical examples. A comparison is made between the heuristic results and daily practice, based on real-life vessel movements through the Van Cauwelaert lock in 2002.     

Evaluating the operational performance of airside and landside at Chinese airports with novel inputs

ABSTRACT

This paper evaluates the operational performance of airside and landside at Chinese airports with two novel inputs. Furthermore, the airport landside operation is decomposed into passenger-terminal operations and cargo-warehouse operations. One novel input is the capability of the runway system which is introduced into airside performance evaluation. The other novel input is cargo warehousing which is introduced into landside performance evaluation. To address multiple optimal solutions when estimating Returns to Scale in Data Envelopment Analysis, we adopted the Zhu and Shen method. This empirical study shows that neither the number of runways nor total runway length is a genuine index of runway system capability in the evaluation of airside performance. Only four airports achieved full efficiency in all eight measures while eight airports did not achieve any full efficiency. In addition, one airport did not perform well in the benchmark analysis.     

Combining Intermodal Transport With Electric Vehicles: Towards More Sustainable Solutions

Abstract

This paper analyses the feasibility of incorporating electric or hybrid vehicles in intermodal transport for the transportation of containers in the pre- and post haulage (PPH) operation. In Europe, the intermodal transport market is being strongly supported, as it is seen as one of the keystones of a sustainable mobility system policy. The introduction of environmentally friendly electric/hybrid vehicles for the pre- and post haulage operation would mean a further enhancement leading to a more complete ecological intermodal transport chain. PPH operations are usually no longer than 30 km, and, hence, could possibly be handled by electric or hybrid vehicles.

Hybrid electric vehicles (HEV) combine electric and other drive systems, such as internal combustion engines, gas turbines and fuel cells. Hybrid electric vehicles merge the zero pollution and high efficiency benefits of electric traction with the high fuel energy density benefits of an energy source or thermal engine. The use of electrically driven vehicles for goods distribution has already been successfully proven in international demonstration projects, such as ELCIDIS. Transport of intermodal units (such as ISO containers), however, requires electric/hybrid heavy-duty goods vehicles, which are not readily available on the market, but for which the technology exists.

Different possibilities are assessed as to their technical, financial, organizational and environmental feasibility and suitability. This analysis is based on a typical mission for pre-and post haulage operations, such as type of trips, distance, frequency, urban/suburban, etc.     

Microscopic simulation of transit operations: policy studies with the MISTRANSIT application programming interface

Abstract

Microscopic traffic simulators are the most advanced tools for representing the movement of vehicles on a transport network. However, the energy spent in traffic microsimulation has been mainly oriented to cars. Little interest has been devoted to more sophisticated models for simulating transit systems. Commercial software has some options to incorporate the operation of transit vehicles, but they are insufficient to properly consider a real public transport system. This paper develops an Application Programming Interface, called MIcroscopic Simulation of TRANSIT (MISTRANSIT), using the commercial microsimulator PARAllel MICroscopic Simulation. MISTRANSIT makes advances in three ways: public transport vehicles can have new characteristics; passengers are incorporated and traced as individual objects; and specific models represent the interaction between passengers and vehicles at stops. This paper presents the modelling approach as well as various experiments to illustrate the feasibility of MISTRANSIT for studying policy operations of transit systems.     

装配式混凝土空心板梁桥单板受力问题的数值解析

借助空间有限元分析软件ABAQUS,分析了装配式空心板梁桥铰缝开裂对桥梁跨中截面荷载横向分布的影响,分析了单侧铰缝开裂、双侧铰缝同时开裂的情况,通过数据回归分析得到了跨中截面荷载横向分布系数随铰缝开裂长度变化的规律,采用等效面积法得到了出现单板受力现象的铰缝开裂临界长度值,分析得出了以下结论:对于单侧铰缝开裂情况,建议临界铰缝长度定为1.0L;对于双侧铰缝开裂情况,建议临界铰缝开裂长度约为0.67L。该研究成果为养护检查中定量化判定"单板受力"问题提供了技术依据,同时也为装配式混凝土空心板梁桥横向整体性加固试验研究提供了理论参考。     

提高水泥混凝土路面横向断缝施工进度的修补技术

水泥混凝土路面在施工过程中出现横向断缝是比较常见的质量问题。文章对如何在保证质量的前提下降低修复成本,并且在合同规定时间内交工进行阐述。     

移动互联网技术在高速公路的应用展望

随着移动互联网技术的发展和用户数量的快速增长,其应用领域也在不断深化拓展,催生了很多新的应用模式.对于高速公路这一传统领域,移动互联网技术一方面可以作为高速企业和行业主管单位业务推广的手段,另一方面也重构了其业务模式,在移动信息发布、交通流量分析、移动数据传输以及车路联网等方面形成了全新的应用方式,深刻地影响和改变了高速公路的管理模式.