Mathematical model for takeoff simulation of a wing in proximity to the ground

Aircraft flying close to the ground benefit from enhanced efficiency owing to decreased induced drag and increased lift. In this study, a mathematical model is developed to simulate the takeoff of a wing near the ground using an Iterative Boundary Element Method (IBEM) and the finite difference scheme. Two stand-alone sub-codes and a mother code, which enables communication between the sub-codes, are developed to solve for the self-excitation of the Wing-In-Ground (WIG) effect. The aerodynamic force exerted on the wing is calculated by the first sub-code using the IBEM, and the vertical displacement of the wing is calculated by the second sub-code using the finite difference scheme. The mother code commands the two sub-codes and can solve for the aerodynamics of the wing and operating height within seconds. The developed code system is used to solve for the force, velocity, and displacement of an NACA6409 wing at a 4° Angle of Attack (AoA) which has various numerical and experimental studies in the literature. The effects of thickness and AoA are then investigated and conclusions were drawn with respect to generated results. The proposed model provides a practical method for understanding the flight dynamics and it is specifically beneficial at the pre-design stages of a WIG effect craft.     

The relationship between maritime education and employer trust: the structural equation modelling (SEM) perspective

The research is aimed to identify factors in the maritime education and training (MET) system and its relationship on maritime labour employers’ (MLEs) trust based on current practice in Malaysia. A questionnaire survey was used, and the respondents were the participants of a related conference in Malaysia. The structural equation modelling technique was used to explain the relationships in the stipulated research model. The test of structural model confirms that the model is adequate in explaining the MLEs’ trust. The results reveal that the perceived MET institutions’ efficiency has significant direct effects on the MLEs’ trust and the perceived seafarers’ competency. In addition, the perceived implementation of International Convention was found to significantly affect the seafarers’ competency. However, the perceived seafarers’ competency was not found to directly affect the MLEs’ trust. This study suggests that the MLEs’ trust is an important indicator and feedback on it can be used to further enhance the current MET system and its policies. Thus, one of the strategies is to develop a policy in order to achieve an effective maritime education and training. This is to support the maritime communities in progressing towards a more sustainable development in the MET in the context of enhancing the maritime safety.     

Use of diesel engine and surface-piercing propeller to achieve fuel savings for inshore fishing boats

Fishing is a major local industry in Malaysia, particularly in rural areas. However, the rapidly increasing price of fuel is seriously affecting the industry’s viability. At present, outboard petrol engines are the preferred choice for use in small-scale fishing boats because they deliver the advantages of high speed and low weight, they are easy to install, and they use minimal space. Petrol outboard engines are known to consume a greater amount of fuel than inboard diesel engines, but installing diesel engines with conventional submerged propellers in existing small-scale fishing boats is not economically viable because major hullform modifications and extra expenditure are required to achieve this. This study describes a proposal to enable reductions in fuel consumption by introducing the combined use of a diesel engine and surface-piercing propeller (SPP). An analysis of fuel consumption reduction is presented, together with an economic feasibility study. Resulting data reveal that the use of the proposed modifications would save 23.31 liters of fuel per trip (40.75 %) compared to outboard motors, equaling annual savings of RM 3962 per year.     

The relative importance of price and driving range on electric vehicle adoption: Los Angeles case study

Electric vehicles (EVs) are still a maturing technology. Barriers to their adoption include price and range anxiety. EV batteries are significant in determining both EV prices and costs. In this work, we focus on the impact of a high-capacity battery and EV rebates on an EV ecosystem. Using survey data from Los Angeles, California, we simulate different cases of battery costs and prices by means of an agent-based EV ecosystem model. We find that even in Los Angeles, a geographically spread out city, the price of EVs is a more significant barrier to adoption than EV range. In fact, even a quintupling of battery size at no additional costs improves EV adoption by only 5 %. Therefore, policy makers should focus more on affordability than range in promoting EV adoption.     

A dynamic approach to road freight flows modeling in Spain

This paper presents an innovative approach to analyzing road vehicle freight traffic that uses a dynamic panel data specification derived from a gravity model. This dynamic approach, which has recently been employed in international goods trade models in lieu of the traditional static specification, is applied to the case of Spain using data for the countrys 15 NUTS-3 regions between 1999 and 2009. Using the system general method of moments approach, we obtained significant evidence that the flow of vehicles carrying commodities by road has a strong persistence effect when controlling for unobserved heterogeneity. We also found that the quality of road transport infrastructure has a significant impact on vehicle trips. According to our findings, we suggest that this type of specification be employed in distribution models in which fixed effects and lags of the dependent variable are included to account for unobserved heterogeneity and persistence effects, respectively.     

Impact of family in-home quality time on person travel demand

This paper introduces the concept of Primary Family Priority Time (PFPT), which represents a high priority household decision to spend time together for in-home activities. PFPT is incorporated into a fully specified and operational activity based discrete choice model system for Copenhagen, called COMPAS, using the DaySim software platform. Structural tests and estimation results identify two important findings. First, PFPT has a place high in the model hierarchy, and second, strong interactions exist between PFPT and the other day level activity components of the model system. Forecasts are generated for a road pricing and congestion scenario by COMPAS and a comparison version of the model system that excludes PFPT. COMPAS with PFPT exhibits less mode changing and time-of-day shifting in response to pricing and congestion than the comparison version.     

Travel mode choice and travel satisfaction: bridging the gap between decision utility and experienced utility

Over the past decades research on travel mode choice has evolved from work that is informed by utility theory, examining the effects of objective determinants, to studies incorporating more subjective variables such as habits and attitudes. Recently, the way people perceive their travel has been analyzed with transportation-oriented scales of subjective well-being, and particularly the satisfaction with travel scale. However, studies analyzing the link between travel mode choice (i.e., decision utility) and travel satisfaction (i.e., experienced utility) are limited. In this paper we will focus on the relation between mode choice and travel satisfaction for leisure trips (with travel-related attitudes and the built environment as explanatory variables) of study participants in urban and suburban neighborhoods in the city of Ghent, Belgium. It is shown that the built environment and travel-related attitudes—both important explanatory variables of travel mode choice—and mode choice itself affect travel satisfaction. Public transit users perceive their travel most negatively, while active travel results in the highest levels of travel satisfaction. Surprisingly, suburban dwellers perceive their travel more positively than urban dwellers, for all travel modes.     

The <Emphasis Type="Italic">Santiago Panel</Emphasis>: measuring the effects of implementing Transantiago

Although panels offer significant advantages over cross sectional data especially in terms of evaluating the effects of significant policy changes, there are precious few examples of panels built around an important change to an urban transport system. For this reason we took the opportunity of the introduction of Transantiago, a radically new public transport system for Santiago de Chile in February 2007, to form a panel, the first wave of which was taken in December 2006. The final objective was to use this Santiago Panel to estimate mode choice models considering both inertia and policy effects. This document describes both the design and construction of the panel, and presents some results based on an analysis of its four waves; for example, we registered a high percentage of mode change (55.1%) attributable to the introduction of the new system. The panel can claim the highest response rate (or lowest attrition) reported in the literature (95% in the second wave, 92% in the third one, and 85% in the forth one). This hints at the possibility of developing sophisticated models to evaluate the effects of a system shock in the presence of inertia in decision making.     

How the longer term success of a social marketing program is influenced by socio-demographics and the built environment

Urban sprawl is pervasive in Australian cities arising from the low density development of dwellings with the consequence that private vehicle use dominates daily travel in Australia. This paper examines a community based social marketing program, TravelSmart, which targeted reducing vehicle kilometres travelled as part of a transport demand management strategy. This paper uses 3-year panel data collected by GPS tracking and a conventional survey methodology in northern Adelaide, South Australia, to examine whether TravelSmart had a sustained impact and whether this was impacted by socio-economic and built-environment factors. A latent growth model is employed and demonstrates TravelSmart led to a declining trend in private car driving over the 3 years at both individual and household levels with effects being sustained beyond 1 year and up to 2 years. There is some evidence of compensatory behaviour between household members. Socio-demographic factors are significant with males decreasing their driving times faster than females. Built environment impacts were also significant with different levels of walkability showing different trajectories in the reduction of car trips after the implementation of TravelSmart, suggesting social marketing interventions work better when supported by hard policies such as a supportive built environment.     

The role of individual characteristics in car ownership shortly after relationship dissolution

The dissolution of a relationship is a life event that often coincides with many other changes in life, such as a decline in income level or household size or a change in place of residence. This study aims to provide more insight into the ways in which circumstances shortly following the disruption of a relationship affect travel behaviour. Register data that combines information on the Dutch population, income and vehicle registration are used to understand how personal situations that are closely related to relationship disruption affect car ownership. The study shows that several characteristics of singles and single partners shortly after a breakup negatively affect car ownership. For instance, a relatively low income level, unemployment, living in a city or a residential move all affect car ownership negatively. This study focuses on the role of circumstances shortly after relationship disruption, demonstrating the importance of such an event.