Railway Vehicles With Generic Bogies Capable of Perfect Steering

The general form of the equations of motion of a symmetric railway vehicle with two unsymmetric two-axle bogies is derived. The equations include a generic elastic stiffness matrix that describes the nature and configuration of the structural connections between the various components of the vehicle. This matrix satisfies the condition for perfect steering (without generating creep forces) on uniform curves and the necessary condition for dynamic stability derived in previous work. The paper shows the application of these basic conditions to a class of generic unsymmetric bogies. The analysis has as its objective the derivation of the simplest rather than the most general configuration that meets the conditions imposed. The results are related to past and current practice. It is shown that perfect steering, with stability at low speeds, can be achieved by means of passive suspension elements not employing linkages, and that it is possible to simplify existing steering arrangements.     

Spatial and Temporal Variability in Shipping Traffic Off San Francisco,California

Shipping traffic poses a worldwide threat to many large whale species. Spatially explicit risk assessments are increasingly being used as a tool to minimize ship-strike risk. These assessments often use static representations of shipping patterns. We used Automatic Identification System data to quantify variability in cargo shipping traffic entering and exiting San Francisco Bay, which contains some of the busiest ports in the United States, at three temporal resolutions: (1) before and after implementation of the California Air Resources Board's Ocean-Going Vessels Fuel Rule, (2) among seasons, and (3) day versus night. We used the nonparametric Mood's Median test to compare median daily distance traveled because the data were not normally distributed and the variance was not homogeneous. Our analyses show that shipping traffic off San Francisco is dynamic at both interannual and daily temporal resolutions, but that traffic was fairly consistent among the seasons considered. Our analyses emphasize the importance of economic and regulatory drivers on interannual shipping traffic patterns. Shipping traffic is expected to continue to change off the U.S. West Coast and to increase globally. These changes in shipping traffic could have implications for the risk of ships striking whales and should be included in risk assessments.     

Solving Nonlinear Differential Equation Governing on the Rigid Beams on Viscoelastic Foundation by AGM

In the present paper a vibrational differential equation governing on a rigid beam on viscoelastic foundation has been investigated. The nonlinear differential equation governing on this vibrating syst...     

Energy policies for passenger motor vehicles

This paper assesses the costs and effectiveness of several energy policies for light-duty motor vehicles in the United States, using a version of the National Energy Modeling System. The policies addressed are higher fuel taxes, tighter vehicle efficiency standards, and financial subsidies and penalties for the purchase of high- and low-efficiency vehicles (feebates). I find that tightening fuel-efficiency standards beyond those currently mandated through 2016, or imposing feebates designed to accomplish similar changes, can achieve by 2030 reductions in energy use by all light-duty passenger vehicles of 7.1–8.4%. A stronger feebate policy has somewhat greater effects, but at a significantly higher unit cost. High fuel taxes, on the order of $2.00 per gallon (2007$), have somewhat greater effects, arguably more favorable cost-effectiveness ratios, and produce their effects much more quickly because they affect the usage rate of both new and used vehicles. Policy costs vary greatly with assumptions about the reason for the apparent myopia commonly observed in consumer demand for fuel efficiency, and with the inclusion or exclusion of ancillary costs of congestion, local air pollution, and accidents.     

An Epsilon Bargaining Game-Theoretic Formulation Between Carrier and Container Terminal Operators for Servicing Vessels During Unloading Operations

Due to globalization trends and the increasing competition between ports, the maritime policy for container shipments has witnessed a change in operations that resulted in less reliance on direct freight flows and higher transshipment operations. Motivated to investigate a soft intelligent decision-making approach using game theory in the context of servicing vessels during unloading operations in transshipment, we propose an epsilon bargaining approach between the carrier and the container terminal operator (CTO). The objective of the game is to maximize the carrier service level while minimizing operation costs for the CTO. The players' utilities, which depend on the service level and the fees for the carrier, as well as the revenues generated and the cost incurred for the CTO, are uniquely formulated and evaluated in a bargaining scenario using an ordinal ranking approach. The negotiation process is further improved between the two players based on our proposed Epsilon Bargaining Equilibrium, which to the best of our knowledge has not been used in maritime transportation problems. Results from a risk aversion case illustrate the value of the soft computing mathematical model that we formulated and motivate follow-up research.     

Rural highway route corridor selection

The selection of a rural highway corridor between designated termini is approached as the simultaneous selection of line and grade of a particular alignment in the corridor. The selection is facilitated by the successive application of linear programming and shortest path techniques. A model is presented in which the inputs are terrain elevations, design constraints on overall grade, terminal grades and elevations, and restricted areas of passage. The output consists of a user‐specified number of alternative corridors, selected on the basis of minimum sum of the deviations of their representative profiles from the original ground. The model is applicable to situations where route selection is dominated by construction considerations. A hypothetical example and an actual application demonstrate the utility of the methodology.     

Pursuing maritime education: an empirical study of students’ profiles,motivations and expectations

This study reveals the profiles, motivations, and expectations of students pursuing undergraduate maritime programmes. Although a number of tertiary institutions offer maritime programmes, the characteristics and structures of the demands for such programmes remain under-researched. This paper illustrates and discusses the results of a survey completed by students pursuing undergraduate programmes in maritime business and management at three universities in Asia and Europe, and compares them with the findings of a database examining similar issues towards postgraduate students within the same institutions. Research highlights include the tendency of undergraduate students to combine studies and work, considering real-world experiences as a vital contributor to career prospects. Shipping (notably tankers, dry bulks and containers) stands out as the ideal professional paths within the maritime industries. Another key finding is that the current marketing strategies of the institutions are rather irrelevant. This paper provides a solid foundation for understanding the profile students pursuing maritime programmes and contributes to the effective planning and management of maritime programmes, thus to the overall professional quality of the maritime industries.     

Experimental study of the flow induced by a vehicle fan and the effect of engine blockage in a simplified model

Fans are often tested without downstream blockage and, thus, the performance is considerably different when the fan is mounted in a vehicle as part of a cooling system and where high blockage effect is present downstream. The aim of the present work is to analyze by laser Doppler velocimetry LDV measurements the topology of the flow induced by a fan incorporated in a simplified underhood model reproducing engine blockage and to study the blockage effect of the engine positioning on the flow induced by the fan. The distance between the fan and the engine block affects the mean flow axial velocity U. The vertical velocity component W is greatly influenced by the variation of the distance between the fan and the engine block, both in magnitude and topology.