Shift of reference point and implications on behavioral reaction to gains and losses

It is widely recognized that individual decision-making is subject to the evaluation of gains and losses around a reference point. The estimation of discrete choice models increasingly use data from stated choice experiments which are pivoted around a reference alternative. However, to date, the specification of a reference alternative in transport studies has been fixed, whereas it is common to observe individuals adjusting their preferences according to a change in their reference point. This paper focuses on individual reactions, in a freight choice context, to a negative change in the reference alternative values, identifying the behavioural implications in terms of loss aversion and diminishing sensitivity. The results show a significant adjustment in the valuation of gains and losses around a shifted reference alternative. In particular, we find an average increase in loss aversion for cost and time attributes, and a substantial decrease for punctuality. These findings are translated to significant differences in the willingness to pay and willingness to accept measures, providing supporting evidence of respondents’ behavioural reaction.     

Experimental study and 3D CFD analysis on the optimization of throttle angle for a convergent vortex tube

Seven adjustments of convergent-type Vortex Tube (VT) with different throttle angles were applied. The adjustments were made to analyze the influences of such angles on cold and hot temperature drops as well as flow structures inside the VTs. An experimental setup was designed, and tests were performed on different convergent VT configurations at injection pressures ranging from 0.45 to 0.65 MPa. The angles of the throttle valve were arranged between 30° to 90°, and the numbers of injection nozzles ranged between 2 and 6. Laboratory results indicated that the maximum hot and cold temperature drops ranged from 23.24 to 35 K and from 22.87 to 32.88 K, respectively, at four injection nozzles. Results also showed that temperature drop is a function of hot throttle valve angle with the maximum hot and cold temperature drops depending on the angle applied. We used graphs to demonstrate the changes in the cold and hot temperature drops with respect to hot throttle angle values. These values were interpreted and evaluated to determine the optimum angle, which was 60°. The CFD outputs agreed very well with the laboratory results. The proposed CFD results can help future researchers gain good insights into the complicated separation process taking place inside the VTs.     

Exploring the drivers of light rail ridership: an empirical route level analysis of selected Australian,North American and European systems

This paper explores the relative influence of factors affecting light rail ridership on 57 light rail routes in Australia, Europe and North America through an empirical examination of route level data. Previous research suggests a wide range of possible ridership drivers but is mixed in clarifying major influences. A multiple-regression analysis of route level ridership (boardings per route km) and catchment residential and employment density, car ownership, service level, speed, stop spacing, share of accessible stops, share of segregated right of away and integrated fares was undertaken. This established a statistically significant model (99% level, R² = 0.76) with five significant variables including service level, routes being in Europe, speed, integrated ticketing and employment density. In general these findings support selected results from previous research. A secondary analysis of service effectiveness measures (boardings/vehicle km, i.e. the relative ridership performance for a given level of service), established a statistically significant model (99% level, R² = 0.67) with 6 significant explanatory variables including being in Europe, speed, employment density, integrated ticketing, track segregation and service level. The latter implies that a higher frequency results in higher service effectiveness. Overall the research findings stress the importance of providing a high level of service as a major driver of light rail ridership. The ‘European Factor’ is also an important though intriguing influence but its cause remains unclear and requires further research to elaborate its nature.     

AUV hull shape design based on desired pressure distribution

The role of autonomous underwater vehicles (AUVs) is more important in the quest to reach the deep seas today than ever before. The hull shape of the AUV can differ depending on the special mission considered for the vehicle. Therefore, different types of algorithms for the body shape design of these kinds of vehicles are being developed every day. In the current work, a new procedure has been proposed for designing the body shape of an AUV. Using this method which is based on a desired pressure distribution, it is possible to obtain the desired hull shape design. Artificial neural network algorithm has been used for this purpose. Preliminary data for training and testing of the network have been obtained from CFD simulation of the flow around the body of Hydrolab500 AUV. In this regard, pressure distribution has been evaluated around each body by changing the nose and tail profile of AUV. The results obtained from this research indicate that a body correlated to the desired pressure can be designed properly.     

Counting people in the crowd using social media images for crowd management in city events

Transportation - City events are getting popular and are attracting a large number of people. This increase needs for methods and tools to provide stakeholders with crowd size information for crowd...     

“I can do perfectly well without a car!”

This article presents the results of a study exploring travellers’ preferences for middle-distance travel using Q-methodology. Respondents rank-ordered 42 opinion statements regarding travel choice and motivations for travel in general and for car and public transport as alternative travel modes. By-person factor analysis revealed four distinct preference segments for middle-distance travel: (1) choice travellers with a preference for public transport, (2) deliberate-choice travellers, (3) choice travellers with car as dominant alternative, and (4) car-dependent travellers. These preference segments differ in terms of the levels of involvement and cognitive effort in travel decision making, the travel consideration-set and underlying motivations. The study showed that for most people there is more to travel than getting from point A to point B, and that there is considerable heterogeneity in middle-distance travel preferences. Policy implications for reducing the need for travel and promoting a modal shift from car to other travel modes are discussed.     

Experimental study comparing racecar aerodynamic downforce-generating devices using scale model NASCAR COT

The performance and safety of the rear wing and spoiler employed on the National Association of Stock Car Auto Racing (NASCAR) COT (car of tomorrow) racecar are experimentally studied using 10 % scale models in a water channel. Particle image velocimetry is used to qualitatively examine the differences in flow structures between the two downforce-generating devices under 0 and 180-degree yaw cases. The latter is important due to an issue with the COT flipping into the air when at extreme yaw (i.e. during a crash). At zero yaw, it is observed that smaller length scales of the flow structures in the wake of the wing compared to those in the wake of the spoiler, provide more predictable handling for racecars in close proximity and may allow more safe and competitive racing. At 180-degree yaw, it is observed that wake-structure interactions may not allow proper operation of anti-flipping devices (roof flaps) on the winged car. In the extreme yaw case, local flow scales are examined and show much stronger Reynolds number (Re) dependence for the wing than the spoiler.     

Optimal power distribution of front and rear motors for minimizing energy consumption of 4-wheel-drive electric vehicles

In this paper, the optimal power distribution of the front and rear motors for minimizing energy consumption of a 4WD EV is investigated. An optimal power distribution control is developed based on the mathematical energy consumption model of an EV. The objective function is defined while ignoring time. And, the time effect is applied by considering the objective function for every single driving point which consists of the vehicle driving force and velocity. From the optimization problem, the optimal torque distribution maps of the front and rear motors can be obtained for all vehicle driving force and velocity ranges. These maps can be expressed using a 3-dimensional map. If the vehicle driving force and velocity are determined, the optimal front and rear motor torques can be determined using these maps. These maps can distribute the front and rear motor torques for the entire velocity range. Thus, these maps can perform the optimal power (torque times speed) distribution of the front and rear motors for minimizing the energy consumption of the 4WD EV. The performance of the optimal power distribution is evaluated by comparing the energy consumption to that of simple power distribution control. For obtaining the energy consumption, a vehicle driving simulation is performed. For the simulation, the driving cycle is required, and the NEDC (New European Driving Cycle) is used. From the simulation results, it is found that the energy consumption of simple power distribution is 4.8 % larger than the optimal one. Thus, the optimal power distribution can minimize the 4WD EV energy consumption as the optimization objective function.     

Modeling and ratio control of an electromechanical continuously variable transmission

A new type of electromechanical continuously variable transmission (EMCVT) was investigated. The EMCVT uses a direct current (DC) motor to push the driving pulley, which in turn changes the transmission ratio without a hydraulic system. This paper introduces the principle of the EMCVT and establishes a dynamic ratio control model. Ratio control strategies using both position and speed closed-loop control are proposed. Simulation results show that the simulation ratio curves of the EMCVT follow pre-designed ratios well for ramp and sine curves. Control software is based on MATLAB/Simulink/Stateflow and MotoHawk platforms. A prototype vehicle equipped with an EMCVT has been developed. Vehicle test results show that the control performance of the EMCVT satisfies the requirements of vehicle operation. The effectiveness of the EMCVT ratio control strategy proposed in this paper is validated with test data for the prototype vehicle.     

Design of a compact 18-speed epicyclic transmission for a personal mobility vehicle

This paper describes the design and shifting dynamics of a novel and small-sized transmission which composed of three epicyclic gear modules and a hub shaft in conjunction with several clutches. The proposed epicyclic gear train can be used in a personal mobility vehicle such as an electric utility vehicle and small car, etc. And it is distinguished from others for its small size, light weight, high efficiency, and wide speed range up to 18 gear steps. In this paper, its dynamic behavior is dealt with in order to ensure the automatic and robust shifts according to the shift commands, focused on the shift mechanism design. First the overall structure and operating principles of the transmission are described in detail. Based on the CAD data of whole components, a detailed multibody dynamic model is built using ADAMS software which can analyze the dynamic behavior of a mechanical system. Then numerical simulations are performed during the shift and whole operating period. From the simulation and experiment results, the overall performance and operating principles of the 18 speed epicyclic transmission are discussed and the design of shift device is optimized to ensure the robust shift finally.