On altruists and egoists in activity participation and travel: who are they and do they live together?

Formulation and specification of activity analysis models require better understanding of time allocation behavior that goes beyond the more recent within household analyses to understand selfish and altruistic behavior and how this relates to travel behavior. Using data from 1,471 persons in a recent 2-day time use/activity diary and latent class cluster analysis we identify 11 distinct daily behaviors that span from the intensely self-serving to intensely altruistic. Predicted cluster membership is then used to study within household interactions. The analysis shows strong correlation exists between social role and patterns of altruistic behavior. However, a substantial amount of heterogeneity is also found within social roles. In addition, travel behavior is also very different among altruistic and self-serving time allocation groups. At the household level, a substantial number of households contain persons with similar behavior. Another group of households contains a mix of self-serving and altruistic persons that follow specialized household roles within their households. The majority of households, however, are populated by altruistic persons. Single person households are more likely to be in the self-serving groups but not in their entirety. Altruism at home is directed most often toward the immediate family members. This is less pronounced when we examine altruistic acts outside the home. Konstadinos G. Goulias is a professor of Geography at the University of California Santa Barbara, has been a professor of Civil Engineering at the Pennsylvania State University from 1991 to 2004, and he is the founder and chair of the TRB task force on moving activity-based approaches to practice. Kriste M. Henson is a technical staff member at Los Alamos National Laboratory in the Decision Applications Division and is currently pursing a Ph.D. in Geography at the University of California—Santa Barbara.     

Computing dynamic user equilibria for large-scale transportation networks

In this paper, we present an approach for determining dynamic user equilibria. The method is suitable for disaggregated microscopic and mesoscopic simulation-based models. It is a modification of the convex-simplex method, which disposes with the line search step, and controls the subset of travelers to be re-routed at each step while updating the link travel times after each assignment. To guarantee finite termination, a suitable stopping criterion is adopted. The proposed method is implemented within TRANSIMS, the Transportation Analysis and Simulation System, as a two-stage process that employs a combined use of link performance functions and a microsimulator in order to design a framework suitable for application to real transportation systems. To demonstrate this capability, we apply the developed methodology to a large-scale network, Bignet, which is part of the transportation city network of Portland, Oregon; and a medium-scale network, Blacksburg, Virginia; and provide some comparative analyses. Our results exhibit that an improved distribution of travelers is obtained while consuming less than 17–33% of the effort required by the current version of TRANSIMS.     

MMAS in Fiji

This article is part of a special issue that provides insight into global conservation science by analyzing a 5-year, $12.5 million global marine conservation science and policy program. In this article, we summarize the development of the program in Fiji. In Fiji, the development of marine managed areas was based on the historical system of Qoli-qoli, moderated by the history of British colonialism, wherein local chiefs and villages controlled access to, and rules for the use of, nearshore marine environments.     

Lessons Learned from the Marine Management Area Science Program: Insights for Global Conservation Science Programs

Drawing on experiences from the four regions and the overall conduct of the Marine Management Area Science (MMAS) program, this concluding article highlights emergent cross-cutting themes that affected MMAS programs across the regions, summarizes the important conservation outcomes of the MMAS program, and then discusses lessons gained from the actual process of conducting the MMAS program. Based on these insights, particularly the last section, this article concludes with recommendations for other conservation programs, specifically those that are global in scope and are science-based with a specific intent to apply that science to conservation action.     

Numerical modeling of hollow-cone fuel atomization,vaporization and wall impingement processes under high ambient temperatures

In the following paper, a numerical study of the atomization, vaporization and wall impingement processes of hollow-cone fuel spray from high-pressure swirl injectors under various ambient temperature conditions was carried out. Also, the availability of applied models and the effect of ambient temperature on spray characteristics is discussed. The Linearized Instability Sheet Atomization (LISA) model combined with the Aerodynamically Progressed Taylor Analogy Breakup (APTAB) model, the improved Abramzon model and the Gosman model are used to calculate the atomization, vaporization and wall impingement processes of hollow-cone fuel spray, respectively. Spray models are implemented with the modified KIVA code. The calculation results of the spray characteristics under two ambient temperatures, including spray tip penetration, spray structure and radial distance after spray-wall impingement are compared to the experimental results obtained by the Laser Induced Exciplex Fluorescence (LIEF) technique. The droplet size distribution, ambient gas velocity field, vapor phase distribution and fuel film mass generated by spray-wall impingement, measurements which are generally difficult to obtain by experimental methods, are also calculated and discussed. Quantitative discussions on the effect of the ambient temperature on the spray development process are conducted. It is shown that the applied models are applicable even in the high ambient temperature condition.     

Activity space estimation with longitudinal observations of social media data

In this paper, we demonstrate the use of an inexpensive and easy-to-collect long-term dataset to address the problems caused by basing activity space studies off short-term data. In total, we use 63,114 geo-tagged tweets from 116 unique users to create individuals’ activity spaces based on minimum bounding geometry (convex hull). By using polygon density maps of activity space, we found clear differences between weekday and weekend activity spaces, and were able to observe the growth trajectory of activity space over 17 weeks. In order to reflect the heterogeneous nature of spatial behavior and tweeting habits, we used Latent Class Analysis twice. First, to identify five unique patterns of location-based activity spaces that are different in shape and anchoring. Second, we identify three unique growth trajectories. The comparison among these latent growth trajectories shows that in order to capture the extent of activity spaces we need long time periods for some individuals and shorter periods of observation for others. We also show that past studies using a single digit number of weeks may not be sufficient to capture individuals’ activity space. The major activity locations identified using a multilevel latent class model, do not appear to be statistically related to the growth patterns of Twitter users activity spaces. The evidence here shows Twitter data can be a valuable complementary source of information for heterogeneity analysis in activity-based modeling and simulation.     

Partial-profilogram reconstruction method to measure the geometric parameters of wheels in dynamic condition

The present work poses a method for the measurement of geometric parameters of rail wheels in a dynamic condition, by reconstructing the profilogram from a portion of the wheel surface wear with artificial vision. The suggested procedure can work with a two-dimensional laser displacement transducer or by processing a sole image from a single camera with a structured light source. These two procedures require fewer devices and simpler implementation processes and allow the use of mathematical algorithms that demand less information processing, thus generating more accurate results. Railway operators may implement this method to perform predictive maintenance to their rolling stock at a fraction of the regular cost; thus achieving better precision, availability, maintenance performance and improving safety. Results were compared to those given by commercial equipment, showing similar precision but a better cost–benefit relation.     

Velocity and normal tyre force estimation for heavy trucks based on vehicle dynamic simulation considering the road slope angle

A precise estimation of vehicle velocities can be valuable for improving the performance of the vehicle dynamics control (VDC) system and this estimation relies heavily upon the accuracy of longitudinal and lateral tyre force calculation governed by the prediction of normal tyre forces. This paper presents a computational method based on the unscented Kalman filter (UKF) method to estimate both longitudinal and lateral velocities and develops a novel quasi-stationary method to predict normal tyre forces of heavy trucks on a sloping road. The vehicle dynamic model is constructed with a planar dynamic model combined with the Pacejka tyre model. The novel quasi-stationary method for predicting normal tyre forces is able to characterise the typical chassis configuration of the heavy trucks. The validation is conducted through comparing the predicted results with those simulated by the TruckSim and it has a good agreement between these results without compromising the convergence speed and stability.     

Cooperative control for friction and regenerative braking systems considering dynamic characteristic and temperature condition

The braking system of hybrid electric vehicle (HEV) is composed of friction and regenerative braking system, meaning that braking torque is generated by the collaboration of the friction and regenerative braking system. With the attributes, there are two problems in the HEV braking system. First, rapid deceleration occurs due to dynamic characteristic difference when shifting the friction and regenerative braking systems. Second, the friction braking torque alters with temperature because the friction coefficient changes with the temperature. These problems cause the vehicle to be unstable. In this paper, the concurrence control and compensation control were proposed to solve these problems. And also, the concurrence control and compensation control were combined for the stability of the braking system. In order to confirm the effect of these control algorithms, the experiment and simulation were conducted. Consequently, it was confirmed that the control algorithm of this study improved the vehicle safety and stability.     

Safety benefits of integrated pedestrian protection systems

This study developed a methodology for evaluating the effectiveness of an integrated pedestrian protection system (IPPS) based on simulations. The proposed IPPS consists of active and passive vehicular systems for protecting pedestrians, including a pedestrian warning information system (PWIS), an active hood lift system (AHLS), and pedestrian airbag system (PAS). Two simulation methods were applied in the proposed methodology: a driving simulation and a finite element simulation. A driving simulator was used to obtain the change in collision speed, which is a key parameter for evaluating driving behavior when a PWIS is applied. In addition, a well-known simulator for finite element analysis, LSDYNA was used to simulate the impact of a pedestrian on a vehicle hood in a pedestrian-vehicle collision. The head injury criterion (HIC), which is an outcome of LS-DYNA simulations, is a major parameter for evaluating passive safety systems. The probability of pedestrian fatalities by collision speeds and HICs were estimated to quantify the safety benefits of an IPPS based on the statistical analyses. The results showed that an IPPS is capable of reducing pedestrian fatalities by approximately 90 % associated with jaywalking in the midblock and walking on the roadside. The findings of this study can be used to boost the development of various vehicular technologies for pedestrians. The results can be effectively used for policy making and deriving legislative requirements associated with advanced vehicular technologies for enhancing pedestrian safety.