Volatility of car ownership, commuting mode and time in the UK

This paper has two objectives: to examine the volatility of travel behaviour over time and consider the factors explaining this volatility; and to estimate the factors determining car ownership and commuting by car. The analysis is based on observations of individuals and households over a period of up to 11 years obtained from the British Household Panel Survey (BHPS). Changes in car ownership, commuting mode and commuting time over a period of years for the same individuals/households are examined to determine the extent to which these change from year-to-year. This volatility of individual behaviour is a measure of the ease of change or adaptation. If behaviour changes easily, policy measures are likely to have a stronger and more rapid effect than if there is more resistance to change. The changes are “explained” in terms of factors such as moving house, changing job and employment status. The factors determining car ownership and commuting by car are analysed using a dynamic panel-data models.     

Design Optimization of a Rear Independent Suspension for the Korean Light Tactical Vehicle

Steering and suspension handle the direction of a vehicle according to the driver’s intentions and control the disturbance from the road surface while supporting the vehicle body. The static and dynamic characteristics of two systems are critical factors for the ride comfort and the directional stability. In the layout stage, the hard points of steering and suspension systems are determined. In the next design stage, the detailed design of the system, including gearboxes, springs, shock absorbers, and control links, is carried out. While the optimal hard points of a suspension are determined at the precedent design, interference with other peripheral components should be carefully examined in the detailed design process. In the case of the design point change should be made to avoid the interference, subsequent position and shape changes of the link mechanism are required. Therefore, there is a need to examine the optimization of suspension compliance characteristics with chassis design changes and the durability performance of the modified design. This study proposes an integrated analysis method for the design optimization and the durability evaluation of such optimized design specifications of the rear independent suspension for a military vehicle.     

Underwater sonar image recognition based on gray-spatial histograms

A new gray-spatial histogram is proposed, which incorporates spatial information with gray compositions without sacrificing the robustness of traditional gray histograms. The purpose is to consider the representation role of gray compositions and spatial information simultaneously. Each entry in the gray-spatial histogram is the gray frequency and corresponding position information of images. In the experiments of sonar image recognition, the results show that the gray-spatial histogram is effective in practical use.     

Measuring and sustaining the UK maritime skills base: A review

Numerous factors over the past three decades have contributed to a major decline in the number of seagoing staff in the United Kingdom. These include shipping companies opting for other flags, as well as the profession itself becoming less and less attractive for school leavers. This decrease in numbers is not only significant for shipping companies, but also for the allied services which used to get supported from seafarers coming ashore in search of a new career. It is now recognised that changes in the maritime skills base will affect both the seagoing as well as the shore side of the industry.     

Numerical simulation of viscous liquid sloshing by moving-particle semi-implicit method

A meshless numerical simulation method, the moving-particle semi-implicit method （MPS） is presented in this paper to study the sloshing phenomenon in ocean and naval engineering. As a meshless method, MPS uses particles to replace the mesh in traditional methods, the governing equations are discretized by virtue of the relationship of particles, and the Poisson equation of pressure is solved by incomplete Cholesky conjugate gradient method （ICCG）, the free surface is tracked by the change of numerical density. A numerical experiment of viscous liquid sloshing tank was presented and compared with the result got by the difference method with the VOF, and an additional modification step was added to make the simulation more stable. The results show that the MPS method is suitable for the simulation of viscous liquid sloshing, with the advantage in arranging the particles easily, especially on some complex curved surface.     

Strip method for a laterally drifting ship in waves

Lateral drift occurs due to the effects of wind forces, wave drifting forces, or both on ships sailing in actual seas. It is important therefore to investigate the influence of lateral drift on seakeeping performance for improved ship operation. The velocity potential was expanded as an asymptotic power series in terms of the lateral speed parameter, τ, defined as ω _e V ₀/g, where ω _e is the frequency of wave encounter; V ₀ denotes the lateral velocity, which is assumed to be sufficiently small; and g is the acceleration due to gravity. By combining this technique with the strip method, two sets of motion equations of all the hydrodynamic force coefficients for ship seakeeping were derived. The first set is for ships without lateral drift and is the same as the equations in the new strip method, and the second set is for the additional motions induced by lateral drift. It was found that all ship motion modes except surge are coupled when a ship drifts laterally in waves.     

Confidence bounds on structural reliability estimations for offshore platforms

Second-order estimates to measure platform reliability are generated and used to provide an additional space to select safety margins appropriate to the owner's perception or for risk-averse managers. The aleatory and epistemic uncertainties in the parameters of an offshore platform are explicitly considered in the reliability analysis and the platform structural reliability becomes a random variable, assessing then the beneficial effects of a reduction on these uncertainties. One of these benefits is for risk-aversive managers who often demand additional room to make conservative decisions regarding reliability estimations. Proposed here is a procedure to generate the frequency diagram of platform reliability with the use of confidence bounds to support reliability and cost decisions based on percentiles instead of mean values. The concepts are illustrated through a typical offshore platform in Mexico. The frequency diagram of the platform reliability index is built for several alternative designs and three levels of epistemic uncertainty. The results may be applied for decision making on new designs and also on the assessment and optimal inspection, retrofit, and decommissioning of existing platforms.     

Two-phase evaporative battery thermal management technology for EVs/HEVs

Electric vehicle’s motor draws power from battery to meet its power demand in different road profiles. Battery high discharged currents are causes of warming battery’s cells. The temperature of 40 ºC and above reduces battery life span. The rationale of fuzzy controlled evaporative battery thermal management system (EC-BThMS) development from this study is to control the battery temperature in the range of 20 ~ 40 ºC both in charging/discharging modes. The proposed system has been developed with estimating the total cooling loads and thermal behavior of the battery cells. A fuzzy controlling system has been introduced with the EC-BThMS to control the electro-compressor and the expansion valve based on the response of battery temperature sensors.A battery pack of 8.6 kWh equipped EV has been operated with 60 km/h on 0 % gradient and 40 km/h on 5 % gradient in IIUM campus while 130 km/h on 0 % gradient and 50 km/h on 3.67 % gradient in Malaysia International Formula circuit to study the battery temperature profile and percentage of battery power saving. Comparison has been made on the performance of EC-BThMS with air cooling battery thermal management system (AC-BThMS) by using same vehicle. Result shows that EC-BThMS can save energy 17.69 % more than AC-BThM 1 and 23 % more than AC-BThM 2.     

Coupled thermo-mechanical analysis and shape optimization for reducing uneven wear of brake pads

In vehicle braking systems, the non-uniform contact pressure distribution on the brake pad is a major cause of uneven wear. The experimental approach of the wear phenomenon is the time consuming and costly. For this reason, a threedimensional finite element (FE) model of a brake system is presented for numerical simulation in this paper. A coupled thermo-mechanical analysis is carried out to confirm the non-uniform contact pressure distribution. A correlation between the non-uniform contact pressure and uneven wear is confirmed by measuring the amount of wear in the brake pad. The shape optimization of the brake pad is performed to reduce the uneven wear. In addition, the simulation results, such as natural frequency and temperature, are compared to experimental results.     

Aerodynamic study of a generic car model with wheels and underbody diffuser

Being a continuous subject of research, this study presents new aspects regarding the relevance of underbody diffusers in road vehicle aerodynamics. Using a generic car model on wheels as a reference, the effect of the wheels on the body fitted with an underbody diffuser was studied, where the diffuser length and angle were varied within ranges which are applicable for hatchback passenger cars. The results show that the vortices which originate from the rear wheelhouses have a major impact on the aerodynamics of the underbody diffuser, which results in increasing of drag and lift of the body. For cases studied, the average drag and lift increment due to the addition of wheels were (Δc_D)_mean = 0.058, respectively (Δc_L)_mean = 0.243. The lift of the body on wheels decreases with both diffuser length and diffuser angle, and there are situations when it may become negative as for a body without wheels. The results show also the possibility to reach a minimum drag according with normalised diffuser length.