Crosswind Sensitivity of Passenger Cars and the Influence of Chassis and Aerodynamic Properties on Driver Preferences

Results of vehicle crosswind research involving both full-scale driver-vehicle tests and associated analyses are presented. The paper focuses on experimental crosswind testing of several different vehicle configurations and a group of seven drivers. A test procedure, which utilized wind-generating fans arranged in alternating directions to provide a crosswind “gauntlet”, is introduced and described. Driver preferences for certain basic chassis and aerodynamic properties are demonstrated and linked to elementary system responses measured during the crosswind gauntlet tests. Based on these experimental findings and confirming analytical results, a two-stage vehicle design process is then recommended for predicting and analyzing the crosswind sensitivity of a particular vehicle or new design.     

Environmental changes in the western Black Sea related to anthropogenic and natural conditions

The Black Sea northwestern shelf (NWS) ecosystem has been subjected to the strongest anthropogenic pressure of the entire Black Sea as about 80% of the freshwater runoff is discharged there.This paper presents a review of the global environmental changes related mainly to increased eutrophication in the western Black Sea basin.A case study (CoMSBlack 92a cruise) attempts to highlight the interaction of some natural and anthropogenic factors responsible for specific chemical and biological features in the western Black Sea environment. The significance of processes located near the Danube river mouth, which, due to their relatively small space scale, have not been recognized before, is clarified. Hydrological processess of specific importance to the distribution and transformation of antropogenic inputs are river plume dynamics, coastal upwelling and mixing and downwelling over the shelf break and slope in this part of the basin. A layer of low hydrological variability (“conservative layer”) appears to be a natural feature of the area, hypothesized to precondition specific biological and chemical processes there.The results suggest that the interplay between the Danube anthropogenic nutrient load with the natural hydrological fronts and gradients provides opportunities for enhanced biological activity thus contributing to the global environmental changes in the Black Sea NWS.     

Link choice proportions from trip distribution and assignment models: An overview and comparison

A number of estimation procedures have been suggested for the situation where a prior estimate of an origin-destination matrix is to be updated on the basis of recently-acquired traffic counts. These procedures assume that both the link flows and the proportionate usage of each link made by each origin-destination flow (referred to collectively as the link choice proportions) are known. This paper examines the possibility and methods for estimating the link choice proportions. Three methods are presented: (1) using ad hoc iteration between trip distribution and traffic assignment; (2) combining trip distribution and assignment in one step; (3) solving a new optimization problem in which the path flows are directly considered as variables and its optimal solution is governed by a logit type formula. The algorithms, covergencies and computational efficiencies of these methods are investigated. Results of testing the three methods on example networks are discussed.     

Optimum throughput and performance evaluation of marine terminals

The performance of marine terminals has generally been evaluated by comparing their actual throughputs with their optimum throughputs. The engineering approach that generally has been used to determine optimum throughputs may be appropriate when terminals have natural hinterlands. In a deregulated (competitive) environment in which the natural hinterlands of marine terminals have become diffused, the economic approach for determining optimum throughputs should be condiered. In such an environment, marine terminals are not only concerned with whether they can handle a given amount of cargo but also whether they can compete for such cargo.     

A linear programming approach to conjoint measurment and trade-off analysis

There has been increasing attention placed on decomposition techniques such as conjoint measurement and trade-off analysis. Existing algorithms for both approaches use non-linear estimation techniques. In this paper, a linear integration rule is proposed along with a linear programming algorithm which is used to estimate part-utilities by minimizing the sum of the absolute deviations subject to monotonicity constraints. The algorithm was tested on simulated data and empirically. It was found that the algorithm performed well, especially when data are consistent with initial assumptions.     

Application of Inverse Models to Vehicle Optimization Problems

This paper presents a nonlinear inverse model of a road vehicle which simulates combined steering and braking/driving. The inputs to the model are the lateral and longitudinal acceleration of the vehicle's sprung mass center. The simulation returns the steering wheel angle and brake/drive torques required to obtain the desired accelerations. An example is presented which demonstrates the utility of inverse models for optimization purposes.     

Shipper's councils: role and responsibility—a western view

Traditionally, liner markets have been seen as dominated by conferences on the seller side, facing small, unorganized shippers onn the buyers' side. This perceived asymmetry has greatly influenced conference legislation in North America (and more recently in the E.U.) and it has been deemed essential that government should regulate conference activities in order to curb any abuse of 'conference power'. In this view, shipowners and shippers are adversaries engaged in a zero-sum battle over transport costs rather than potential or actual partners in global distribution systems. This paper suggests that in today's global markets much can be achieved by cooperationn in the development of logistics systems and that shipowners and shippers may have much to gain from such cooperative alliances. A survey of shippers' councils in 1991-1992 demonstrates the diversity and increasing sophistication of many national shippers' councils, which devote themselves to the task of improving markets through education and the legislative process. The situation in the U.S.A. is different: for legal reasons, conventional shippers' councils do not exist. Instead, 'shippers' associations' play a commercial role in liner markets. It is suggested that European style shippers' councils can and should play an important role in the development and formulation of policies for internatinal liner markets. Such participation requires a cooperative industry environment quite different from the traditional adversarial approach, which is ill suited to global trade and logistics alliances.