Information impact on quality of multimodal travel choices: conceptualizations and empirical analyses

This paper investigates the impact of a variety of travel information types on the quality of travel choices. Choice quality is measured by comparing observed choices made under conditions of incomplete knowledge with predicted choice probabilities under complete knowledge. Furthermore, the potential impact of travel information is considered along multiple attribute-dimensions of alternatives, rather than in terms of travel time reductions only. Data is obtained from a choice experiment in a multimodal travel simulator in combination with a web-based mode-choice experiment. A Structural Equation Model is estimated to test a series of hypothesized direct and indirect relations between a traveler’s knowledge levels, information acquisition behavior and the resulting travel-choice quality. The estimation results support the hypothesized relations, which provides evidence of validity and applicability of the developed measure of travel-choice quality. Furthermore, found relations in general provide some careful support for the often expected impact of information on the quality of travel choices. The effects are largest for information services that generate previously unknown alternatives, and lowest for services that provide warnings in case of high travel times only.

The influence of built environment to the trends in commuting journeys in the Netherlands

In this paper we describe commuting trends in the Netherlands in the past decade and examine the influence of urban form and travel accessibility on commuting journeys over time on the basis of data from the Dutch National Travel Survey. Exploratory analysis is performed to identify changes in commuting participation, departure time, commuting time, commuting distance and the modal split. Regression analysis and choice models are used to examine the influence of the built environment on commuting parameters over time. The results indicate that urban form has consistently influenced the parameters of commuting journey in the Netherlands in the last 10 years. However, the trend of the influence is unique for each commuting model. Some influences have become less significant in the last decade and some have become stronger.

A “rutter for piracy” in 2012

This "rutter for piracy" begins with a brief update on contemporary piratical incidents and a short review of books and collections of articles dedicated to the topic of piracy, before presenting the ground-breaking group of scholarly essays which make up WMU Journal of Maritime Affairs' special issue on piracy at sea.     

A fully coupled ship motion and sloshing analysis in various container geometries

In the present study a novel modeling approach is presented to solve the combined internal sloshing and sea-keeping problem. The model deals with interesting effects arising due to the coupled interaction between the sloshing in partially filled containers of several geometries and the ship motion. The study is very important for the liquid cargo carrier operating in rough sea or under different environmental conditions. The resulting slosh characteristics that include transient pressure variation, free surface profiles and hydrodynamic pressure over the container walls have been reported in this study. In addition, the effects of coupled ship response and sloshing on ship motion parameters have also been investigated. The equations of motion of fluid, considered inviscid, irrotational, and partially compressible, are expressed in terms of the pressure variable alone. A finite difference-based iterative time-stepping technique is employed to advance the coupled solution in the time domain. Several parameters of interest, including the container parameters, level of liquid, thrusters modeling and some important environmental factors are investigated.     

Shifting control of an automated mechanical transmission without using the clutch

The automated mechanical transmission (AMT) is gaining popularity in the automotive industry, due to its combination of the advantages of mechanical transmissions (MT) and automatic transmissions (AT) in terms of fuel consumption, low cost, improved driving comfort and shifting quality. However, the inherent structural characteristics of the AMT lead to disadvantages, including excessive wear of the clutch plates and jerk and traction interruption during the shift process, that severely affect its popularity in the automatic transmission industry. The emerging technology of shifting control without the use of the clutch is a promising way to improve the shifting transients of AMTs. This paper proposes a control algorithm that combines speed and torque control of the AMT vehicle powertrain to achieve shifting control without using the clutch. The key technologies of accurate engine torque and speed control and rapid position control of the shift actuators are described in detail. To realize accurate engine speed control, a combined control algorithm based on feed-forward, bang-bang and PID control is adopted. Additionally, an optimized closed-loop position control algorithm based on LQR is proposed for the shift actuators. The coordinated control algorithm based on engine and shift actuator control is described in detail and validated on a test vehicle equipped with an AMT. The results show that the coordinated control algorithm can achieve shifting control without the use of the clutch to improve driving comfort significantly, reduce shift transients and extend the service life of the clutch.     

Numerical investigation of a DI diesel spray flame using a detailed chemical reaction mechanism

Emission standards have grown increasingly stricter, consequently triggering greater interest in issues surrounding environmental pollution. In particular, soot and NOx released from DI diesel vehicles is considered to be the main source of air pollution in urban environments. However, the mechanics of fuel spray formation and the influence of the operating parameters on the resulting spray flame are not yet fully understood. In this study, the original KIVA code was modified to incorporate a detailed chemical reaction mechanism involving various species and multiple reaction steps to better understand the spray characteristics. n-Heptane, C₇H₁₆, was used as the representative fuel for diesel fuel, and the reaction mechanism for this fuel was composed of 66 species and 274 elementary reaction steps. The accuracy of the predicted results was demonstrated primarily by a comparison with experimental results. The numerical prediction of a specific operating condition for the parametric investigation correlates well with the experimental results.     

A comparative study on the power characteristics and control strategies for plug-in hybrid electric vehicles

A comparative study was performed on two types of plug-in hybrid electric vehicles (PHEVs): the GM Volt and the Toyota Prius Plug-in Hybrid. First, the powertrain models of the two vehicles were derived. Based on the dynamic models, a detailed component control algorithm was developed for each PHEV. Specifically, a control algorithm was proposed for motor generator 1 (MG1) and MG2 to achieve optimal engine operation. Additionally, an energy management strategy for selecting the operation mode was developed from the viewpoint of fuel economy, battery state of charge and vehicle velocity. Using the dynamic model of the control algorithm for each PHEV, simulations were performed, and the simulation results were verified by comparing them with those obtained using the Powertrain System Analysis Toolkit simulator for the plug-in Prius. Based on the simulation results, a comparative study was performed, and it was found that the role and capacity of MG1 and MG2 and the mode selection algorithm must be determined depending on the configuration of the PHEV.     

Influence of the accelerating operation mechanism on the combustion noise in DI-diesel engines

This paper focuses on the mechanisms of combustion noise during the accelerating operation of multi-cylinder diesel engines using testing technology for the transient conditions of IC engines. Based on impact factors, such as the gas dynamic load and cylinder pressure oscillations, tests and analysis of the combustion noise during transient and steady-state conditions for different loads are made on four-cylinder naturally aspirated engines, turbocharged engines, EGR-introduced engines, and high pressure common rail engines. The laws of combustion noise difference for the same engine speed and load are researched during transient and steady-state conditions. It is found that during transient conditions, the maximum pressure rise rate and the high frequency oscillation amplitude of the cylinder pressure are all higher than those observed during steadystate conditions for the same engine speed and load. With their joint action, the combustion noise during transient conditions is greater than that during steady-state conditions. Turbocharging is useful in reducing the combustion noise during transient conditions. Turbocharging has a better effect on the control over the combustion noise during transient conditions with a constant engine speed and an increasing torque than in conditions with a constant torque and an increasing engine speed. One of the main reasons for different control effects on the combustion noise is that turbocharging causes different wall temperatures inside combustion chambers. The introduction of the appropriate EGR is helpful in the reduction of the combustion noise during transient conditions. The key to the control of combustion noise with EGR during transient conditions is whether a real-time adjustment to the EGR rate can be made to achieve the optimization of the EGR rates for different transient conditions. By means of analyzing the differences in the combustion noise between the transient and steady-state conditions for different pilot injection controls, we obtain a strategy for controlling the combustion noise during transient conditions with a pilot injection. Compared with the steady-state conditions, a larger pilot injection quantity and a longer interval between the main injection and pilot injection should be selected for transient conditions, and this is verified through tests.     

Sensitivity analysis for reducing critical responses at the axle shaft of a lightweight vehicle

Critical responses are frequently detected at the coupled torsional beam axle (CTBA) of a lightweight vehicle. However, the freedom to modify the design of the axle shaft is limited because the suspension system must satisfy other vehicle requirements such as steering performance. Conventional sensitivity analysis cannot provide practical information about the resonant behavior because the analysis only identifies the contribution of the axle shaft to the behavior. This paper presents a novel sensitivity analysis based on transmissibility ratios (TRs). The vehicle components other than the axle shaft that can be modified to control the critical spectra are identified using acceleration responses. A multi-body vehicle model is constructed to simulate the proposed design modifications, and the simulation results show that the vibration of the axle shaft is considerably reduced by the modifications. Because the TRs on the CTBA are effectively minimized through the modified design strategy, the resonant response from the axle shaft can be controlled efficiently.     

Brazil’s new vehicle front impact safety standards — ABNT NBR 15300-1 & ABNT NBR 15300-2 or ABNT NBR 15300-3: Is the manufacturerer choice the safest for the passenger?

To increase car passenger safety, the Brazilian National Traffic Council (CONTRAN) released Resolution 221, which defines the maximum passenger and driver biomechanical criteria in the event of a vehicle frontal impact. The vehicle maximum allowed biomechanical injury criteria will be enforced from January 2012 for new vehicles and in January 2014 for vehicles in production before January 2014. To standardize the test method to measure the driver and front passenger injury values in a frontal crash, Resolution 221 states that the tests must be performed according to the ABNT NBR 15300-1 standard, followed by the ABNT NBR 15300-2 standard or the ABNT NBR 15300-3 standard. The use of ABNT NBR 15300-2 or ABNT NBR 15300-3 standards is a free choice for the manufacturer of the vehicle. The ABNT NBR 15300-1 + 15300-2 test is similar to the FMVSS 208 standard in the United States in terms of its vehicle frontal impact test perpendicular to a rigid barrier with the use of seat belts by male model dummies. The test according to ABNT NBR 15300-1 + 15300-3 follows the European ECE R94 and 96/79/EC standards. However, ABNT NBR 15300-2 focuses on occupant protection during vehicle deceleration rather than occupant protection during vehicle deformation in a crash test. ABNT NBR 15300-3 tests occupant protection during vehicle deformation more than it tests occupant protection during vehicle deceleration. Therefore, this paper aims to show the types of test results produced by the ABNT NBR 15300-2 and ABNT NBR 15300-3 standards and their differences concerning occupant protection verification and discuss the manufacturer??s freedom of choice.