High-Speed Rail Operations on an Existing Network: An Assessment Model for China

High-speed rail operations have the potential to reduce the long-term decline in rail passenger travel demand for the medium to long distance inter-urban markets. Such decline has been evident through most of the industrialized countries where air and road transport tend to be the dominant modes. In China, the operations of long distance high-speed rail on fully dedicated track is not very easy to implement, due to the high proportion of passengers who travel between high-speed and conventional railways. An alternative approach would be to allow for mixed operations with trains of various speeds on the same track. This article puts forward a simulation model designed to allow an evaluation of the most efficient distance for high-speed rail operations under mixed train speed scenarios. The model takes into account the main operating parameters such as passenger volumes, train speeds, capital and maintenance costs, train operating costs and energy consumption. The distance of high-speed train running on conventional rail that will yield the most economic benefit can be estimated using the model. The article includes the results of using the model for a specific example. It is concluded that large-scale high-speed trains have the potential to be successfully operated on conventional rail networks.     

Ranking of factors contributing to higher performance in the ocean transportation industry: a multi-attribute utility theory approach

The North American Free Trade Agreement (NAFTA) signed by Canada, the U.S.A. and Mexico and which came into effect on 1 January 1994, is a significant move towards further integration of the North American economies. This paper examines the likely impact of NAFTA on Canadian ports. Three channels of impact are identified. First, there are direct impacts on trade flows between Canada and its North American trading partners. In this regard we find that ports do not typically handle the types of products that are likely to be affected by NAFTA, and so the direct impacts may be minimal. Second, and more significantly, port catchment areas are likely to undergo substantial changes as they respond to a more competitive environment within the free trade area. Third, the transportation sector has itself been included in NAFTA, and Canadian ports will face increased competition from land based transportation modes. We conclude that ports in Canada must learn to work more consciously as agents of regional economic development.     

Damage detection of offshore jacket structures using frequency domain selective measurements

The development of damage detection techniques for offshore jacket structures is vital to prevent catastrophic events. This paper applies a frequency response based method for the purpose of structural health monitoring. In efforts to fulfill this task, concept of the minimum rank perturbation theory has been utilized. The present article introduces a promising methodology to select frequency points effectively. To achieve this goal, modal strain energy ratio of each member was evaluated at different natural frequencies of structure in order to identify the sensitive frequency domain for damage detection. The proposed methodology opens up the possibility of much greater detection efficiency. In addition, the performance of the proposed method was evaluated in relation to multiple damages. The aforementioned points are illustrated using the numerical study of a two dimensional jacket platform, and the results proved to be satisfactory utilizing the proposed methodology.     

Low-aspect ratio appendages for wind-assisted ships

Journal of Marine Science and Technology - Wind propulsion for commercial ships has been identified as a key component in the energy transition for the maritime industry. The sailing hybrid ship...     

A fractional perspective to the modelling of Lisbon’s public transportation network

Transportation - Urban growth originates multiscale spatial patterns, such as those of transportation networks. Here, the public transportation network (PTN) of the city of Lisbon is analysed from...     

Comparison of Beach Nourishment along the U.S. Atlantic,Great Lakes,Gulf of Mexico,and New England Shorelines

The U.S. national beach nourishment experience is summarized for the East Coast barrier islands, the Gulf of Mexico, New England, and the Great Lakes. A total of 1,305 nourishment episodes on 382 beaches are recorded at a total estimated cost of approximately $1.4 billion ($2.5 billion in 1996 dollars). In terms of both volume and costs, nourishment has been the most extensive by far on the East Coast barrier islands. Depending on the region, between 65% and 85% of all nourishment projects have a federal funding component. Annual expenditures and sand volumes for beach nourishment are increasing, especially on East Coast barriers. At present, total annual national beach nourishment costs (excluding the Pacific Coast) are on the order of $100 million per year. The cost per cubic yard of nourishment sand as expressed in 1996 dollars has remained more or less constant over time. Additionally, the volumes of sand needed for subsequent nourishment episodes on individual beaches do not decrease, despite contrary assumptions in the shoreface-profile-ofequilibrium concept that subsequent nourishment volumes should diminish. In light of the historical experience of beach nourishment identified in this study, individual state and local coastal communities should reevaluate their plans for future beach nourishment programs. The complete listing of all the data on nourished beaches from this survey is available at www.geo.duke.edu/Research/psds/psds.htm     

Hysteresis in travel demand

This paper presents evidence that there is a hysteresis effect in the demand for transport usage with respect to price. Consequently the neoclassical concept of a smooth continuous demand curve is questioned. The author presents a hysteresis model whereby changes in demand and of demand are embraced in a single theory related to generalized cost.     

Application of a real-coded genetic algorithm for the fitting of a ship hull surface through a single non-uniform B-spline surface

In digital ship-design processes, surface modeling needs to be as accurate as possible for effectiveness in ship production as well as numerical analysis of the performance. Traditionally, the form of a ship hull is constructed from a set of cross-sectional data. This approach entails difficulties in the cross-sectional spacing and accuracy of the characteristic curves, such as the stern and bow profiles, deck side line, bottom tangential line, and unconnected curves. Genetic algorithms (GAs) have attracted increasing attention as a multimodal optimization solution for surface reconstruction that enable construction of a single non-uniform B-spline (NUB) surface at the initial stage of ship design with constraints such as knuckles, discontinuity conditions, and bulbous bows with high curvatures, . The first, simultaneous multi-fitting GA determines the boundary curves, such as the stem and stern profiles, and finds the common knot values for both curves. Similarly, the same GA technique is applied for other boundary curves at the bottom and the deck. The second GA is employed to fit the interior data points after the boundary curves are fitted. The encoded design variables for surface construction are the locations of the vertices and the knot values. Those variables are modified for improving the surface quality until a predefined degree of precision is attained. In four instances of application, the GA technique developed in this research has been shown to provide good, single, NUB surfaces with high efficiency. In the early design stage, a single NUB surface is more convenient for performance visualization and finite-element methods. It can be readily translated into many CAD/CAM packages, which facilitate the smooth transition of data across the different design stages.     

Some managerial and technical issues in transport sector development projects

In development projects there is only one problem, but it is huge: everything is connected to everything else. The authors separated from the whole the following important issues: (1) Project management and coordination: The Recipient Country’s Aid Coordination Unit (ACU) and Project Implementation Unit (PIU) staffed with competent local experts are necessary to hold the reform process memory. This issue is considered in the context of “Ownership” and “Government Leadership” as it is recognized in donor aid forums in the last decade. (2) Human resource development: Most technical assistance is oriented toward providing solutions, and the development of local capacities is ignored. The authors point out the importance of specially selected local experts—the “Technical Communication Officers”. (3) Institutional functioning: A ‘process consultation’ approach to institutional restructuring is promoted in which the Recipient has the key role. It is also recommended that the Recipient is the initiator of technical assistance in the projects. (4) Design standards are a recurrent and difficult problem. Recommendations are necessary how to transit to the new standards and how to mediate their approval process. (5) Procurement and management of consulting services: The authors argue that the recipient country qualified professionals have to be in the lead role. The vignettes in the paper are from the “real world” although they are modified slightly to protect privacy.     

Modeling and analysis of a fuel-injection pump used in diesel engines

The Fuel-Injection Pump (FIP) used in diesel engine has a higher-pair cam-mechanism to pressurize the fuel for injection. This paper proposes a methodology to model FIP from a multibody Dynamics (MBD) perspective. The results from the model include the temporal behavior of driving torque, contact Hertz stress and reaction forces at various joints. The model helps the designer to assess the effect of various cam profiles, link parameters and other design variables. It is necessary that these parameters be optimized for future high pressure applications. For this purpose, a cam-mechanism with offset follower axis is analysed. Decoupled Natural Orthogonal Complement (DeNOC) matrices based algorithm is used to model FIP without and with offset cam-mechanism. The study shows that, the offset cam-mechanism allows reduction in the side-thrust, reaction forces, and the contact Hertz stress acting on the cam-follower interface. As a typical case, for an FIP working around a pressure value of 600 bar, an optimum offset value is found to be 9.5 mm and it shows a reduction of about 45% in side thrust values. To validate the modeling approach, experimental studies are performed on pump without and with offset cam-mechanism. Experimental results are in qualitative agreement with the theoretical model results.