Editor's note on the comments from Eugene P. Odum,Howard T. Odum,Leonard Shabman,and Sandra Batie

Abstract

It was pointed out in a recent article on shorelines management in France that no overall coastal management legislation in that country exists.¹ Nevertheless, certain existing legislation has been adapted to take account of the peculiarities of the shoreline and coastal zone, and new institutions such as the “Shorelines Trust”; have been created.² As is the case with most countries in the Western world, the processes of urbanization, industrialization, and recreational development place tremendous pressure on shoreline use. Resulting conflicts are sometimes difficult to solve unless adequate institutional frameworks exist. Some form of institutional change is thus inevitable.     

The potential role of public–private partnerships in the upgrade of port infrastructure: normative and positive considerations

There is a broad consensus on the need for the major expansion of many ports. Traditionally, ports and related facilities have involved significant levels of direct or indirect government ownership or some degree of government financing. Most governments, however, are reluctant to either borrow money to fund the needed additional capital infrastructure or to fund it directly. Public–private partnerships (P3s) are thus an attractive potential option. But are they the answer? This article examines the normative rationales for P3s and presents a positive theory perspective that focuses on the conflicting goals of public and private partners. It argues that the major government impetus for P3s is likely to be for physical port infrastructure with moderate levels of market failure, such as small to medium sized ports, and not for intangible port activities. Furthermore, small to medium sized port P3s are likely to be successful in terms of having relatively low transaction costs and lower total social costs than alternative provision mechanisms. Nonetheless, even in this situation, the different goals of public and private partners may give rise to conflict. Drawing on the global empirical evidence on P3s, this article proposes some institutional design features that will help to ensure P3 success.     

Review of GPS Travel Survey and GPS Data-Processing Methods

Abstract

Global positioning system (GPS) devices have been utilised in travel surveys since the late 1990s. Because GPS devices are very accurate at recording time and positional characteristics of travel, they can correct the trip-misreporting issue resulting from self-reports of travel and improve the accuracy of travel data. Although the initial idea of using GPS surveys in transport data collection was just to replace paper-based travel diaries, GPS surveys currently are being applied in a number of transport fields. Several general reviews have been done about GPS surveys in the literature review sections in some papers, but a detailed systematic review from GPS data collection to the whole procedure of GPS data processing has not been undertaken. This paper comprehensively reviews the development of GPS surveys and their applications, and GPS data processing. Different from most reviews in GPS research, this paper provides a detailed and systematic comparison between different methods from trip identification to mode and purpose detection, introduces the methods that researchers and planners are currently using, and discusses the pros and cons of those methods. Based on this review, researchers can choose appropriate methods and endeavour to improve them.     

Flexible strategic planning of transport systems

Abstract

This paper presents a decision support methodology for long-range planning of transport systems that exhibits strategic flexibility and stochastic system parameters. Unlike one-off strategic decisions, flexible decisions should be dynamically reformulated with time. The proposed methodology is based on the construction of a tree structure of multiple interlinked tactical planning problems, each associated with a scenario in the tree, where problems under scenarios at intermediate dates incorporate in their formulation the solution of the corresponding problems associated with past (future) connected scenarios. The resulting tree structure of interconnected planning decisions becomes a strategic-tactical decision support system that allows managers to formulate suitable flexible strategic decisions that mitigate the consequences associated with downside scenarios while taking advantage of the upside opportunities. The methodology is applied to the planning of a fleet deployment through charter contracts where contract prices depend on both market behavior and the duration of the contract itself.     

Modeling residential sorting effects to understand the impact of the built environment on commute mode choice

This paper presents an examination of the significance of residential sorting or self selection effects in understanding the impacts of the built environment on travel choices. Land use and transportation system attributes are often treated as exogenous variables in models of travel behavior. Such models ignore the potential self selection processes that may be at play wherein households and individuals choose to locate in areas or built environments that are consistent with their lifestyle and transportation preferences, attitudes, and values. In this paper, a simultaneous model of residential location choice and commute mode choice that accounts for both observed and unobserved taste variations that may contribute to residential self selection is estimated on a survey sample extracted from the 2000 San Francisco Bay Area household travel survey. Model results show that both observed and unobserved residential self selection effects do exist; however, even after accounting for these effects, it is found that built environment attributes can indeed significantly impact commute mode choice behavior. The paper concludes with a discussion of the implications of the model findings for policy planning.

Integration of experiment and hydrostatic fluid-structure finite element analysis into dynamic characteristic prediction of a hydraulically damped rubber mount

Hydraulically damped rubber mount (HDM) can effectively attenuate vibrations transmitted between an automotive powertrain and body/chassis and reduce interior noise in the car compartment. Predicting the dynamic characteristics of a HDM faces challenges due to fluid-structure interactions between the rubber spring and fluid in the chambers, nonlinear material properties of the rubber parts and turbulent flow in the chambers and fluid track linking chambers. In this paper, an experimental analysis and hydrostatic finite element (FE) modeling technique are integrated in a numerical simulation approach to modeling the dynamic characteristics of a HDM with a lumped-parameter HDM model. The dynamic characteristics of a typical HDM with a fixed decoupler are predicted and compared with experimental results, which verify the effectiveness of the proposed approach. Moreover, a parametric effect analysis is performed to demonstrate parameter influence on dynamic characteristic, which provides a concise design guideline for the parameter adjustments necessary for a HDM to meet the vibration isolation requirements of a powertrain mount system.     

沥青混合料烟雾与材料力学性能之间的关系

着重于研究热拌沥青混合料生产过程中产生的烟雾与沥青力学性能之间的关系,涉及的影响因素有温度、沥青种类以及一些动力学参数。研究者在试验室拌和机上安装了气体取样设备,能够在正常拌和的同时对热拌沥青混合料烟雾中的多环芳香烃(PAH)以及有机化合物(TOC)进行取样分析。通过对沥青材料进行室内性能指标的测试,发现在所有指标中回收沥青的复合模量与沥青烟雾排放量的相关性最好,因为它的结果同时反映了材料的物理性能以及沥青氧化和老化的程度。同时还建立了热拌沥青混合料烟雾排放与拌和参数以及混合料力学性能之间的关系。     

Investigation of the shear flows over a sunroof opening based on a linear inviscid instability analysis

The large-scale shear flows over the sunroof opening of a mid-sized SUV measured using a PIV system were investigated. The shear flows were measured for five different cases of deflector protrusion (one case was the baseline test without deflector) at two different free stream flow velocities below the critical velocity where the buffeting noise level reached a maximum. The structures of the shear flows were observed to differ, apparently depending on whether the radiated buffeting noise is relatively strong or not. For strongly buffeting experimental cases, the momentum thicknesses of the shear layers were observed to grow rapidly and saturated at a station near the downstream edge of the sunroof opening, where the saturation of the transverse velocity fluctuations was also observed, and where the vortex coalescence process was presumably completed. On the other hand, no discrete large-scale vortex structures were observed for none-buffeting or weakly buffeting cases. Streamwise growth of the velocity fluctuations was found to be well predicted by a linear hydrodynamic instability analysis for the strongly buffeting cases. Numerical results obtained from a linear inviscid instability analysis using a hyperbolic tangent mean velocity profile were used to calculate the amplification factors with the initial momentum thickness and the streamwise fluctuation wavenumber. The shear flows were found to form large-scale discrete vortices when the linear inviscid amplification factors exceeded a threshold amplification factor.     

机械电子技术在未来铁道车辆中的应用与发展(待续)

全面介绍了机械电子技术在未来铁道车辆特别是悬挂系统、牵引系统和制动系统中的应用和发展。     

澳大利亚重载列车纵向动力的研究

在进行BHP铁矿石重载运输时,列车平均轴重在35t以上、整列车由220辆车组成的情况已为数不少,列车的纵向动力常常会大于1000kN。20世纪90年代中期,高的列车纵向力导致列车沿着坡度大的坡道下行和在起伏很大的路段上运行时出现列车分离。与修改车辆维修工艺和操作程序一样,对列车驾驶方法进行了研究和修正,并对列车实际操作进行了调整。通过一系列的措施,大大减少了列车延误次数。