GPS-based speed collection method for road traffic noise mapping

One of the most difficult and expensive tasks in making noise pollution maps is the collection and processing of the data needed to create acoustic models. In the case of road traffic noise maps, obtaining speed data for light and heavy vehicles a problem that has usually been avoided by using a road’s speed limit or by making assumptions based on experience from similar road types. Here global positioning systems-based techniques are applied for acquiring vehicle speed data and adapted to fulfill the requirements of noise prediction models.     

Between-mode-differences in the value of travel time: Self-selection or strategic behaviour?

Using stated preference survey data, we measure the value of travel time for several transport modes. We find, like many before us, that the value of travel time varies across modes in the opposite direction of what would be the consequence of differences in comfort. We examine three candidate causes for the observed differences: Comfort effects, self-selection and strategic behaviour of respondents. Using experiments with both the current and an alternative mode we find that the differences in the value of travel time are consistent with self-selection and comfort effects. Moreover, respondents having bus as the current or the alternative mode seem not to value comfort differently across modes. Strategic behaviour seems to play no role.     

Simulation optimization of the berth allocation in a container terminal with flexible vessel priority management

ABSTRACT

Solving the berth allocation problem (BAP) in ports is not trivial where the berth resources are limited and various sizes of vessels arrive with dramatically dissimilar loads. Especially in real scenarios, arriving vessels are accepted for a berth with the first come first served (FCFS) priority rule. This study proposes a decision support system coupled with a simulation optimization module based on the swarm-based Artificial Bee Colony optimization algorithm for solving the BAP. The proposed methodology was implemented for the Izmir port in Turkey. To investigate the influences of the vessel priorities on the BAP, four different experimental scenarios based on the single (SQM) and multiple queue models (MQM) were coupled with FCFS and proposed hybrid queue priority (HQP) rule. The results indicated that SQM scenarios were superior to MQM scenarios in a manner of minimizing the average vessel waiting times and the implementation of a dynamic berth allocation strategy for the MQM significantly decreases the vessel waiting times. Results of the SQM also imply that utilization of the HQP approach further minimizes the average vessel waiting times and increases the berth utilization and port throughput without yielding excessive waiting times for the larger vessels compared with the FCFS priority rule.     

Oceanic CO2 uptake and biogeochemical variability during the formation of the Eastern North Atlantic Central water under two contrasting NAO scenarios

Long-term variability of the biogeochemical properties during the formation of central waters in the Eastern North Atlantic were analyzed between 42–47°N and 10–20°W from the dataset gathered during the Galicia VII (GVII) and C. Darwin 58/59 (CD58/59) cruises. These cruises that showed important changes in the thermohaline properties and the nutrient abundance of the upper layers were carried out under contrasting conditions of the North Atlantic Oscillation (NAO) index. The different climate forcing led a meridional shift of the transition zone between the formation regions of subpolar and subtropical Eastern North Atlantic Central Water (ENACWp and ENACWt, respectively). This displacement conditioned the presence of each ENACW in the study region and so the thermohaline and biogeochemical properties. The effect of the observed variability at decadal scale on the air–sea CO₂ gradient (ΔfCO₂) and exchange (F_CO2) was analyzed using 1D model approach throughout 11 weekly-steps that simulated the development of a spring bloom during the shoaling of the mixed layer. The outputs of the model showed an intensification of the ocean CO₂ uptake due to higher biological CO₂ drawdown, during positive NAO conditions and its weakening under negative NAO influence.     

Residence time,exposure time and connectivity in the Scheldt Estuary

Residence times and exposure times are computed for 13 boxes in the Scheldt Estuary, using the high-resolution tracer-transport model SLIM. The concepts are clearly defined and related to how they should be computed. First, the timescale values are compared with results published previously that were obtained with a simple box model, and an unexpected difference is revealed. This may suggest that a high-resolution model is necessary, even for the computation of such integrated quantities as residence or exposure times. Secondly, the newly computed residence times are compared to the exposures times to illustrate their intrinsic differences. From this difference, it is possible to propose a return coefficient, expressing the fraction of the exposure time that is due to “returning water”, i.e. water which has already left the estuary at least once. Finally, the estuarine exposure times are decomposed into the different box exposure times, resulting in a connectivity matrix. This matrix expresses how much time is spent in each of the estuarine subdomains during the water parcels' journey through the estuary.     

A traffic analysis zone definition: a new methodology and algorithm

This paper develops a comprehensive approach to the definition of transportation analysis zones (TAZ), and therein, presents a new methodology and algorithm for the definition of TAZ embedded in geographic information systems software, improves the base algorithm with several local algorithms, and comprehensively analyses the obtained results. The results obtained are then compared to these presently used in the transportation analysis process of the Lisbon Metropolitan Area. The proposed algorithm presents a new methodology for TAZ design based on a smoothed density surface of geocoded travel demand data. The algorithm aims to minimise the loss of information when moving from a continuous representation of the origin and destination of each trip to their discrete representations through zones, and focuses on the trade-off between the statistical precision, geographical error, and the percentage of intra-zonal trips of the resulting OD matrix. The results for the Lisbon Metropolitan Area case study suggest a significant improvement in OD matrix estimates compared to current transportation analysis practises based on administrative units.

A Computational Procedure for Non-Linear Dynamic Analysis of Vehicles

In the research and design of vehicles, the accurate simulation of their dynamic behaviour is often of interest. Therefore, on the one hand, the non-linear properties of suspensions and tyres may not be neglected. On the other hand, the application of large mechanical models is necessary in order to get correct information about the local dynamic behaviour of critical parts or elements of vehicles. With regard to these requirements, in this paper, a special computational procedure is presented for the non-linear dynamic analysis of vehicles using large finite element models. Correctness, in comparison to COSMOS/M commercial finite element program, and applicability of the presented procedure is shown by the use of a bus finite element model containing 2214 degrees of freedom.     

Geometric modelling of bulbous bows with the use of non-uniform rational B-spline surfaces

Nowadays, bulbous bow forms have become a common design feature in most conventional ship designs. The design of a bulbous bow is usually attempted with the use of certain form parameters that are imposed using the designer's experience or regression values that provide the optimum parameters based on experimental tests or computational fluid dynamics (CFD) calculations. In this article, the geometric modelling of a bulbous bow form that complies with a series of parameters is presented. First, a wire model was constructed with cubic B-spline curves that hold certain form parameters that the designer wants to impose. Second, a B-spline surface that fits these splines was mathematically constructed. A review of the influence of the design parameters used on the bulbous bow properties was made. This method could be used prior to numerical optimization of a bulbous bow because different variations of the design can be easily generated. These variations can be tested numerically using CFD software. A practical application example of the method is shown.     

An optical tire contact pressure test bench

An optical tire contact pressure test bench developed by the IMMa group is described. The measurement system is based on the frustration of total internal reflection (FTIR) of light. The test bench allows performing normal pressure distribution and patch contact shape measurements on passenger car tires. The system is based on the use of a laterally illuminated glass on which the tire leans. Between them a plastic interphase is located that will cause the FTIR of light. A video camera catches the formed shining image through the glass. The brightness level in each pixel of the image can be related to the existing normal pressure. The study of the contact patch provided by the bench makes it possible to characterize tire behaviour under different loading states, inflation pressure, tire defects and toe and camber angles. The bench incorporates a computerized load and control system of the tire operation parameters, an image acquisition module and a data acquisition system that allow monitoring and acting on the experimental variables of interest in the tests such as load on the tire and environmental conditions. A supporting mechanical system incorporated to the bench allows providing the tire with variable toe and camber angles. From the images obtained with this system, the maximum normal pressure points, total force, size and shape of the patch can be determined, which are related to the tire-use conditions. As an application example, results that show the patch size and shape under different load and tire inflation pressures are presented. A further application, which is the use of the system for the detection and study of defective tires is also presented.